2024/09/09 更新

写真a

カワサキ ヒデヤ
川崎 英也
KAWASAKI,Hideya
所属
化学生命工学部 教授
職名
教授
連絡先
メールアドレス
プロフィール

■ 学位:九州大学 博士(理学)
■ 專門分野:界面・コロイド化学,分析化学,ナノ材料化学
■ 主な研究テーマ:
・ナノ粒子の新規合成法の開発と機能化
・機能性ナノ粒子の光学特性、触媒特性、及び電気伝導性
・機能性ナノ粒子の応用展開(環境エネルギー、エレクトロニクス情報、ライフサイエンス医療分野)
■ 受賞:日本質量分析学会 : 論文賞(平成 26 年,平成 27 年 ), 奨励賞 (平成22年), 優秀論文賞(平成 19 年 )
日本化学会 コロイドおよび界面化学部会: 奨励賞(平成 15 年), 松浦賞(平成 11 年)
■ 所属学会:日本化学会,日本化学会コロイドおよび界面化学部会, 日本分析化学会,日本質量分析学会,ナノ学会,高分子学会,日本油化学会, 日本ソノケミストリー学会, アメリカ化学会 (ACS)
■ 学会役職:日本化学会 界面コロイド部会 (関西支部長:2020~ , 事業企画委員, 討論会委員), 日本分析化学会 (副支部長:2018、関西支部幹事), 日本質量分析学会 (68th 討論会実行委員長、材料分析部会委員), 日本油化学会 ( 関西支部幹事), 日本化学会 新領域研究グループ 「分散凝集の学理構築への科学と技術戦略」(代表)
■ Editorial Board: 1) Nanomaterials(2020~), 2) Mass Spectrometry(2020~), 3)Analytical Sciences(2017~2020)

外部リンク

学位

  • 博士(理学) ( 1998年3月 )

研究キーワード

  • 触媒

  • 発光

  • ナノ粒子・ナノ構造体

  • 分光分析

  • 質量分析

  • 抗菌

  • 電子材料

研究分野

  • ナノテク・材料 / ナノ構造化学

  • ナノテク・材料 / ナノ材料科学

  • ナノテク・材料 / 基礎物理化学

  • ナノテク・材料 / 分析化学

学歴

  • 九州大学大学院   理学研究科   化学専攻

    1995年4月 - 1998年3月

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    国名: 日本国

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  • 三重大学大学院   工学研究科工業化学専攻

    1993年4月 - 1995年3月

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  • 三重大学   工学部   工業化学科

    - 1993年3月

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経歴

  • 関西大学   化学生命工学部 化学・物質工学科   教授

    2013年4月 - 現在

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  • 関西大学   化学生命工学部 化学・物質工学科   准教授

    2007年4月 - 2013年3月

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  • 関西大学   工学部応用化学科   助教授

    2006年4月 - 2007年3月

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  • 九州大学大学院助手(理学研究院)

    2000年4月 - 2006年3月

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  • 九州大学   理学部   助手

    1999年11月 - 2000年3月

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  • 日本学術振興会特別研究員(九州大学大学院理学研究科)

    1998年4月 - 1999年10月

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所属学協会

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委員歴

  • 将来構想委員  

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  • 日本化学会   事業企画委員  

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  • 日本化学会   若手WG委員長  

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  • 日本化学会   デイビジョン幹事  

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  • 日本化学会   役員会幹事  

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  • 日本化学会   支部幹事  

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  • 支部幹事  

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  • 事業企画委員;若手WG委員長;役員会幹事;支部幹事;デイビジョン幹事;将来構想委員  

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論文

  • Piezoelectric nanomaterials for antibacterial strategies 査読 国際共著

    Xiebingqing Yang, Zhuoren Yang, Xuesong Wang, Yahui Guo, Yunfei Xie, Weirong Yao, Hideya Kawasaki

    Applied Materials Today   40   102419 - 102419   2024年10月

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    担当区分:最終著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

    DOI: 10.1016/j.apmt.2024.102419

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  • Degradation of Aqueous Tetracycline Hydrochloride through Radical-based Advanced Oxidation Processes Using UV 222 nm/S2O8 2− and UV 222 nm/H2O2 査読

    22 ( 4 )   194 - 203   2024年8月

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    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    添付ファイル: Degradation of Aqueous Tetracycline Hydrochloride through Radical-based Advanced Oxidation Processes.pdf.pdf

    DOI: 10.2965/jwet.24-026

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  • Effect of Gold Nanoparticle Size on Regulated Catalytic Activity of Temperature-Responsive Polymer−Gold Nanoparticle Hybrid Microgels 査読

    Palida Pongsanon, Akifumi Kawamura, Hideya Kawasaki, Takashi Miyata

    Gels   10 ( 6 )   357 - 357   2024年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:MDPI AG  

    Gold nanoparticles (AuNPs) possess attractive electronic, optical, and catalytic properties, enabling many potential applications. Poly(N-isopropyl acrylamide) (PNIPAAm) is a temperature-responsive polymer that changes its hydrophilicity upon a slight temperature change, and combining PNIPAAm with AuNPs allows us to modulate the properties of AuNPs by temperature. In a previous study, we proposed a simpler method for designing PNIPAAm–AuNP hybrid microgels, which used an AuNP monomer with polymerizable groups. The size of AuNPs is the most important factor influencing their catalytic performance, and numerous studies have emphasized the importance of controlling the size of AuNPs by adjusting their stabilizer concentration. This paper focuses on the effect of AuNP size on the catalytic activity of PNIPAAm–AuNP hybrid microgels prepared via the copolymerization of N-isopropyl acrylamide and AuNP monomers with different AuNP sizes. To quantitatively evaluate the catalytic activity of the hybrid microgels, we monitored the reduction of 4-nitrophenol to 4-aminophenol using the hybrid microgels with various AuNP sizes. While the hybrid microgels with an AuNP size of 13.0 nm exhibited the highest reaction rate and the apparent reaction rate constant (kapp) of 24.2 × 10−3 s−1, those of 35.9 nm exhibited a small kapp of 1.3 × 10−3 s−1. Thus, the catalytic activity of the PNIPAAm–AuNP hybrid microgel was strongly influenced by the AuNP size. The hybrid microgels with various AuNP sizes enabled the reversibly temperature-responsive on–off regulation of the reduction reaction.

    DOI: 10.3390/gels10060357

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  • Self-stacking two-layer conductive films for enhanced oxidation and low electrical resistance from hybrid ink of cobalt/copper 査読

    Ryota Sakaida, Hideya Kawasaki

    Materials Letters   136238 - 136238   2024年2月

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    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

    DOI: 10.1016/j.matlet.2024.136238

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  • A study on the PEG-assisted stability of spherical nucleic acid constructed by the freezing method 査読 国際共著 国際誌

    Han Dong, Letian Zhong, Yuliang Cheng, Hang Yu, Yunfei Xie, Weirong Yao, Yahui Guo, Hideya Kawasaki

    Colloids and Surfaces A: Physicochemical and Engineering Aspects   133349 - 133349   2024年1月

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    担当区分:最終著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

    The freezing method used to prepare DNA-modified gold nanoparticles (SNA) has the advantages of being fast and simple, but the prepared SNA is easy to aggregate. In this paper, the effects of polyethylene glycol (PEG) as an organic macromolecular crowding agent on the single-strand polyadenylate DNA functionalized gold nanoparticles (polyA-SNA) and the single-strand thiolated DNA functionalized gold nanoparticles (HS-SNA) were systematically studied. The experimental results showed the molecular weight and concentration of PEG significantly affect the dispersion and DNA loading of the two kinds of SNA. An increase in DNA strand length inhibits the adsorption of thiolated DNA and polyA-DNA, and the hydrated particle size of SNA increases at first and then decreases with the length of the DNA strand. These phenomena lay on the speculative principle that PEG improved the energy barrier for gold nanoparticles (AuNPs) aggregation through the long chain of macromolecules, and the modification mode and length of surface DNA also play an auxiliary role. This work provided a systematic study and helpful results on improving the stability of SNA prepared by the freezing method.

    DOI: 10.1016/j.colsurfa.2024.133349

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  • Oxidation inhibition of gallium–indium liquid metal particles in carbonated water under ultrasonic irradiation 査読

    Materials Chemistry and Physics   314   128844   2023年12月

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    担当区分:責任著者   記述言語:英語  

    DOI: 10.1016/j.matchemphys.2023.128844

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  • Controllable Catalytic Activity of Temperature-Responsive Polymer Hybrid Microgels Designed Using a Gold Nanoparticle Monomer with Polymerizable Groups 査読

    Palida Pongsanon, Yoshiko Oota, Akifumi Kawamura, Hideya Kawasaki, Takashi Miyata

    Macromolecules   2023年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society (ACS)  

    DOI: 10.1021/acs.macromol.3c01659

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  • Preparation and Catalytic Function of Substituted Polyacetylenes Coordinated to Palladium Nanocluster 査読

    T. Nagata, T. Suzuki, H. Kawasaki, Y. Obora, H. Sogawa, F. Sand

    Polym., Japan   44   275 - 285   2023年11月

  • Activated platinum in gallium-based roomtemperature liquid metals for enhanced reduction reactions 査読

    Nichayanan Manyuan, Hideya Kawasak

    RSC Advances   13   30273   2023年10月

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    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1039/D3RA06571E

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  • A Review on Gold Nanoclusters for Cancer Phototherapy 査読 国際共著 国際誌

    Zhuoren Yang, Xiebingqing Yang, Yahui Guo, Hideya Kawasaki

    ACS Appl. Bio Mater.   2023年10月

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    担当区分:最終著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/acsabm.3c00518

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  • 第2 章 粉体の生成と生産プロセス 2.2 液相中の粒子生成 2.2.4 化学還元法を用いた金属ナノ粒子の液相合成 招待

    川﨑英也

    60 ( 7 )   429 - 434   2023年7月

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    担当区分:筆頭著者   記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.4164/sptj.60.429

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  • Dry liquid metals stabilized by silica particles: Synthesis and application in photothermoelectric power generation 査読

    Nichayanan Manyuan, Tomoko Otsuki, Yusuke Tsumura, Syuji Fujii, Hideya Kawasaki

    Journal of Colloid and Interface Science   649, 581-590   2023年6月

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    Hypothesis: Gallium-based room-temperature liquid metals (LMs) have unique physicochemical properties;however, their high surface tension, low flowability, and high corrosiveness to other materials limit their advanced processing (including precise shaping) and application. Consequently, LM-rich free-flowing powders, named “dry LMs” that offer the inherent advantages of dry powders, should play a critical role in expanding the application scope of LMs. Experiments: A general method of preparing silica-nanoparticle-stabilized LMs in the form of LM-rich powders (>95 wt% LM) is developed. Findings: Dry LMs can be simply prepared by mixing LMs with silica nanoparticles in a planetary centrifugal mixer in the absence of solvents. As a sustainable dry-process route alternative to wet-process routes, this ecofriendly and simple method of dry LM fabrication has several advantages, e.g., high throughput, scalability, and low toxicity owing to the lack of organic dispersion agents and milling media. Moreover, the unique photothermal properties of dry LMs are used for photothermal electric power generation. Thus, dry LMs not only pave the way for the use of LMs in powder form but also provide a new opportunity for expanding their application scope in energy conversion systems.

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  • Microwave-Assisted Incorporation of AgNP into Chitosan–Alginate Hydrogels for Antimicrobial Applications

    Takuma Oe, Duangkamol Dechojarassri, Sachiro Kakinoki, Hideya Kawasaki, Tetsuya Furuike, Hiroshi Tamura

    Journal of Functional Biomaterials   2023年4月

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.3390/jfb14040199

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  • Highly bright full color emission from dye doped silica nanoparticles with prevention of dye self quenching 査読

    S. Saita, K. Niwa, Y. B. Pottathara, H. Kawasaki

    Opt. Mater   139, 113803   2023年4月

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  • Rose bengal-decorated rice husk-derived silica nanoparticles enhanced singlet oxygen generation for antimicrobial photodynamic inactivation. 査読 国際誌

    N. Mori, H. Kawasaki, E. Nishida, Y. Kanemoto, H. Miyaji, J. Umeda, K. Kondoh

    J. Mater. Sci.   1 - 13   2023年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1007/s10853-023-08194-z

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  • Carbon nanodots with a controlled N structure by a solvothermal method for generation of reactive oxygen species under visible light 査読

    Satoshi Saita, Hideya Kawasaki

    Luminescence   38 ( 2 )   127 - 135   2023年1月

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    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Wiley  

    Abstract

    Carbon nanodots can function as photosensitizers that have the ability to generate reactive oxygen species such as singlet oxygen, hydroxy (OH) radicals, and superoxide ions. However, most of these can only be generated upon ultraviolet light excitation. Additionally, the mechanism of reactive oxygen species generation by carbon nanodots remains unclear. The development of carbon nanodots that can photosensitize under visible light irradiation is desirable for applications such as photodynamic therapy and pollutant decomposition under visible light. Here, we report novel carbon nanodot‐based photosensitizers that generate reactive oxygen species under visible light; they were synthesized using a solvothermal method with two solvents (formamide and water) and amidol as the carbon source. Carbon nanodots from the solvothermal synthesis in formamide showed blue fluorescence, while those obtained in water showed green fluorescence. The photo‐excited blue‐fluorescent carbon nanodots produced OH radicals, superoxide ions, and singlet oxygen, and therefore could function as both type I and type II photosensitizers. In addition, photo‐excited green‐fluorescent carbon nanodots generated only singlet oxygen, therefore functioning as type II photosensitizers. It is proposed that the two photosensitizers have different origins of reactive oxygen species generation: the enrichment of graphitic N for blue‐fluorescent carbon nanodots and molecular fluorophores for green‐fluorescent carbon nanodots.

    DOI: 10.1002/bio.4428

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    その他リンク: https://onlinelibrary.wiley.com/doi/full-xml/10.1002/bio.4428

  • Singlet Oxygen Generation Using Thiolated Gold Nanoclusters under Photo- and Ultrasonic Excitation: Size and Ligand Effect 査読

    J. Yagi, A. Ikeda, L.-C. Wang, C.-S. Yeh, H. Kawasaki

    J. Phys. Chem. C   2022年11月

  • UV-absorbing Ligand Capped Gold Nanoparticles for the SALDI-MS Analysis of Small Molecules 査読

    T. Kakuta, N. Manyuan, H. Kawasaki

    Mass Spectrometry   2022年11月

  • Recent advances in gas sensing technology using non-oxide II-VI semiconductors CdS, CdSe, and CdTe 査読

    M. Ando, H. Kawasaki, S. Tamura, Y. Shigeri

    Chemosensors   10, 482   2022年11月

  • 酸化グラフェンとカオチン界面活性剤による透明超薄膜コーティングの持続的抗菌効果

    宮治 裕史, 金本 佑生実, 浜本 朝子, 蔀 佳奈子, 西田 絵利香, 加藤 昭人, 菅谷 勉, 田中 佐織, 相川 夏葉, 川崎 英也, 郷田 隼, 小野 博信

    日本バイオマテリアル学会大会予稿集   44回   394 - 394   2022年11月

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    記述言語:日本語   出版者・発行元:日本バイオマテリアル学会  

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  • Sustained antibacterial coating with graphene oxide ultrathin film combined with cationic surface-active agents in wet environment 査読

    H. Miyaji, Y. Kanemoto, A. Hamamoto, K. Shitomi, E. Nishida, A. Kato, S. Tsutomu, S. Tanaka, N. Aikawa, H. Kawasaki, S. Gohda, H. Ono

    Sci Rep   12, 16721 ( 1 )   2022年10月

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1038/s41598-022-21205-4

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    その他リンク: https://www.nature.com/articles/s41598-022-21205-4

  • Liquid metal catalyst for the conversion of ethanol into graphitic carbon layers under ultrasonic cavitation field 査読

    Hideya Kawasaki, Tomoko Otsuki, Fumiya Sugino, Ken Yamamoto, Tomoharu Tokunaga, Rintaro Tokura, Tetsu Yonezawa

    Chem. Commun.   2022年6月

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  • Hansen Solubility Parameter Analysis on Dispersion of Oleylamine-Capped Silver Nanoinks and their Sintered Film Morphology Oleylamine-Capped Silver Nanoinks and their Sintered Film Morphology 査読

    Satoshi Saita, Shin-ichi Takeda, Hideya Kawasaki

    Nanomaterials   12, 2004   2022年6月

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  • Deracemization of 1-phenylethanols in a one-pot process combining Mn-driven oxidation with enzymatic reduction utilizing a compartmentalization technique 査読

    H. Sato, R. Yamada, Y. Watanabe, T. Kiryu, S. Kawano, M. Shizuma, H. Kawasaki

    RSC Advances   12, 10619-10624 ( 17 )   10619 - 10624   2022年4月

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1039/d2ra01326f

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  • Reversible sensing of nitrogen dioxide using photoluminescent CdSe/ZnS quantum dots and enhanced response by combination with noble metals CdSe/ZnS quantum dots and enhanced response by combination with noble metals 査読

    Masanori ANDO, Kosuke INAGAKI, Hideya KAWASAKI, Yasushi SHIGERI

    Journal of the Ceramic Society of Japan   130 [1] 180-186 2022 ( 1 )   180 - 186   2022年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.2109/jcersj2.21088

    Web of Science

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  • One-pot analysis of enantiomeric excess of free amino acids by electrospray ionization mass spectrometry 査読

    T. Nakakoji, H. Sato, D. Ono, H. Miyake, E. Mieda, S. Shinoda, H. Tsukube, H. Kawasaki, R. Arakawa, M. Shizuma

    RSC Advances   11, 36237 – 36241 ( 57 )   36237 - 36241   2021年11月

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1039/d1ra06542d

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  • リゾチーム-金ナノクラスター/ローズベンガル複合体の抗菌・抗バイオフィルム光線力学的活性

    岡本 一絵, 宮治 裕史, 宮田 さほり, 菅谷 勉, 蔀 佳奈子, 赤坂 司, 齋田 慧, 川崎 英也

    日本歯周病学会会誌   63 ( 秋季特別 )   133 - 133   2021年10月

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    記述言語:日本語   出版者・発行元:(NPO)日本歯周病学会  

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  • TiO2-supported Au144 nanoclusters for enhanced sonocatalytic performance 査読

    Kouhei Kawamura, Atsuya Ikeda, Ayaka Inui, Ken Yamamoto, Hideya Kawasaki

    The Journal of Chemical Physics   155, 124702(2021)   2021年9月

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  • Highly Conductive, Flexible, and Oxidation-Resistant Cu-Ni Electrodes Produced from Hybrid Inks at Low Temperatures 査読

    Daisuke Tomotoshi, Rika Oogami, Hideya Kawasaki

    ACS Applied Materials & Interfaces (ACS)   2021年4月

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  • Antibacterial and Antibiofilm Photodynamic Activities of Lysozyme- Au Nanoclusters/Rose Bengal Conjugates 国際誌

    Ichie Okamoto, Hirofumi Miyaji, Saori Miyata, Kanako Shitomi, Tsutomu Sugaya, Natsumi Ushijima, Tsukasa Akasaka, Satoshi Enya, Satoshi Enya, Hideya Kawasaki

    ACS   6 ( 13 )   9279 - 9290   2021年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/acsomega.1c00838

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  • Controlled Aggregation of Methylene Blue in Silica–Methylene Blue Nanocomposite for Enhanced 1O2 Generation 査読

    Satoshi Saita, Maho Anzai, Nanase Mori, Hideya Kawasaki

    Colloids and Surfaces A: Physicochemical and Engineering Aspects   2021年2月

  • One-step Synthesis of M13 Phage-based Nanoparticles and Their Fluorescent Properties 査読

    J. Yi Lai, N. Inoue, C. W. Oo, H. Kawasaki, T. Soon Lim

    RSC Advances   11, 1367-1375   2021年1月

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  • Nanocellulose-Based Flexible Energy Storage Devices

    Pottathara, Y.B., Tiyyagura, H.R., Kawasaki, H., Ahmad, Z., Thomas, S., Kokol, V.

    Nanocellulose: Synthesis, Structure, Properties And Applications   2021年

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Nanocellulose: Synthesis, Structure, Properties And Applications  

    DOI: 10.1142/9781786349477_0014

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  • Origin of the fluorescence in silica-based nanoparticles synthesized from aminosilane coupling agents 査読

    Satoshi Saita, Hideya Kawasaki

    Journal of Luminescence   2020年12月

  • Enantioselectivity-evaluation of chiral copper(II) complexes coordinated by novel chiral tetradentate ligands for free amino acids by mass spectrometry coupled with the isotopically labeled enantiomer method 査読

    T. Nakakoji, H. Sato, H. Miyake, S. Shinoda, H. Tsukube, H. Kawasaki, R. Arakawa, D. Ono, M. Shizuma

    Frontiers in chemistry   8   2020年11月

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.3389/fchem.2020.598598

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  • Conductive leaf vein networks produced via Ag nanoparticle self-assembly for potential applications of flexible sensor 査読

    P. Keller, H. Kawasaki

    Mater. Lett   284, 128937   2020年11月

  • Antibacterial/Photosensitizing Action of Thiolate-protected Metal Nanoclusters and Their Application to Antimicrobial Photodynamic Therapy 査読

    Kanako Shitomi, Hirofumi Miyaji, Hideya Kawsaki

    Acc. Mater. Surf. Res.   5(3), 68-80   2020年9月

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  • Surface and Interface Designs in Copper-Based Conductive Inks for Printed/Flexible Electronics 査読

    Daisuke Tomotoshi, Hideya Kawasaki

    Nanomaterials   2020年8月

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  • 金銀クラスター/ローズベンガル含有キトサンナノゲル複合体の光線力学的特性

    浜本 朝子, 加藤 昭人, 宮田 さほり, 蔀 佳奈子, 宮治 裕史, 菅谷 勉, 齋田 慧, 川崎 英也

    北海道外科雑誌   65 ( 1 )   91 - 91   2020年6月

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    記述言語:日本語   出版者・発行元:北海道外科学会  

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  • Tungsten (VI) oxide and titanium dioxide doping with gold nanocluster (Au NCs) for photocatalytic enhancement in methylene blue photodegradation 査読

    Is Fatimah, Eka Akbar Kurniastuti, Hideya Kawasaki

    AIP Conference Proceedings   2229, 030035   2020年4月

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  • Synthesis and Characterization of N,N-Dimethylformamide-Protected Palladium Nanoparticles and Their Use in the Suzuki–Miyaura Cross-Coupling Reaction 査読

    J. Ishida, M. Nakatsuji, T.Nagata, H. Kawasaki, T.Suzuki, Y. Obora

    ACS Omega   2020年4月

  • Photoluminescent Ozone Sensor with Enhanced Sensitivity by Using CdSe/ZnS Quantum Dots Modified with Gold and Platinum 査読

    Masanori ANDO, Kosuke INAGAKI, Hideya KAWASAKI, Vasudevanpillai BIJU, Yasushi SHIGERI

    Analytical Sciences   https://doi.org/10.2116/analsci.19P490   2020年3月

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  • Photodynamic inactivation of oral bacteria with silver nanoclusters/rose bengal nanocomposite. 国際誌

    Kanako Shitomi, Hirofumi Miyaji, Saori Miyata, Tsutomu Sugaya, Natsumi Ushijima, Tsukasa Akasaka, Hideya Kawasaki

    Photodiagnosis and photodynamic therapy   30   101647 - 101647   2020年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Antibacterial photodynamic therapy (a-PDT) is a promising anti-infective technique for generation of singlet oxygen (1O2) to target dental disease. However, conventional organic photosensitizers have some problems for clinical use in terms of cytotoxicity, quenching of a-PDT activity by self-dimerization, and the lack of long-term antibacterial effect. We herein propose silver nanoclusters/rose bengal nanocomposite (AgNCs/RB) as a novel photosensitizer with two primary antibacterial effects: (1) 1O2 generation by irradiated RB and (2) Ag+ ion release from AgNCs. AgNCs/RB irradiated with white light-emitting diode (LED) for a short irradiation time of 1 min significantly decreased the bacterial turbidity of Streptococcus mutans, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans (P < 0.05). In SEM, TEM and LIVE/DEAD staining images, photoexcited AgNCs/RB reduced S. mutans colonization, destroyed the cell membrane, and increased the number of dead cells. The antibacterial efficiency of photoexcited AgNCs/RB was greater than that of AgNCs or RB alone (P < 0.05), suggesting a synergistic effect of 1O2 and Ag + ions from photoexcited AgNCs/RB. By contrast, photoexcited AgNCs/RB did not affect WST-8 and LDH activities and morphology of NIH3T3 mammalian cells, indicating low cytotoxicity. Interestingly, the antibacterial activity of AgNCs/RB on S. mutans was maintained even after the cessation of LED irradiation, indicating a long-term antibacterial effect due to released Ag+ ions. The present AgNCs/RB photosensitizers provide effective synergistic antibacterial effects for dental a-PDT via 1O2 and Ag+ ions coupled with low cytotoxicity.

    DOI: 10.1016/j.pdpdt.2019.101647

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  • Photoluminescent ozone sensor with enhanced sensitivity by using CdSe/ZnS quantum dots modified with gold and platinum

    Ando, M., Inagaki, K., Kawasaki, H., Biju, V., Shigeri, Y.

    Analytical Sciences   36 ( 8 )   2020年

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.2116/analsci.19P490

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  • Photo/electrocatalysis and photosensitization using metal nanoclusters for green energy and medical applications

    Kawawaki, Tokuhisa, Negishi, Yuichi, Kawasaki, Hideya

    Nanoscale Adv.   2   2020年

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:RSC  

    DOI: 10.1039/C9NA00583H

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  • Mass spectrometric detection of enantioselectivity in three-component complexation, copper(II)-chiral tetradentate ligand-free amino acid in solution 査読

    T. Nakakoji, H. Sato, D. Ono, H. Miyake, S. Shinoda, H. Tsukube, H. Kawasaki, R. Arakawa, M. Shizuma

    Chemical Communications   56 ( 1 )   54 - 57   2019年11月

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1039/c9cc07231d

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  • 合金クラスター/ローズベンガル含有キトサンナノゲルの抗菌性評価

    加藤 昭人, 宮治 裕史, 齋田 慧, 川崎 英也

    日本バイオマテリアル学会大会予稿集   41回   367 - 367   2019年11月

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    記述言語:日本語   出版者・発行元:日本バイオマテリアル学会  

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  • Ultrasonic Activation of Water-Soluble Au25 (SR) 18 Nanoclusters for Singlet Oxygen Production 査読

    Kouhei Kawamura, Daiki Hikosou, Ayaka Inui, Ken Yamamoto, Junichi Yagi, Satoshi Saita, Hideya Kawasaki

    J. Phys. Chem. C   https://doi.org/10.1021/acs.jpcc.9b08492   2019年10月

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  • Human dentin applied with silver nanoclusters exhibited the antibacterial activity on Streptococcus mutansin applied with silver nanoclusters exhibited the antibacterial activity on Streptococcus mutans 査読

    K Shitomi, H Miyaji, S Miyata, E Nishida, K Mayumi, T Sugaya, H Kawasaki

    Nano Biomed   11 ( 1 )   121 - 28   2019年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Mild synthesis of single-nanosized plasmonic copper nanoparticles and their catalytic reduction of methylene blue 査読

    Kousuke Kuroda, Philip Keller, Hideya Kawasaki

    Colloid and Interface Science Communications   31   2019年6月

  • 銀ナノクラスターで被覆したヒト象牙質はStreptococcus mutansに対する抗菌活性を示す(Human Dentin Coated with Silver Nanoclusters Exhibits Antibacterial Activity against Streptococcus mutans) 査読

    Shitomi Kanako, Miyaji Hirofumi, Miyata Saori, Nishida Erika, Mayumi Kayoko, Sugaya Tsutomu, Kawasaki Hideya

    Nano Biomedicine   11 ( 1 )   21 - 28   2019年6月

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    記述言語:英語   出版者・発行元:ナノ・バイオメディカル学会  

    虫歯の病原菌であるStreptococcus mutansに対して審美的(象牙質変色予防)作用と抗菌的作用を持つ成分として、直径2nm未満の銀ナノクラスター(AgNC)を調製した。このAgNCはS.mutansの濁度と生存性を顕著に減少させるだけでなく、LIVE/DEAD染色法にて殺菌効果が認められた。このAgNCをヒト象牙質に適用すると、フッ化ジアミン銀を適用した場合と比べて象牙質の変色は認められず、AgNC-処理象牙質はS.mutansによるコロニー形成に対する阻害効果を示した。これらの結果から、AgNCは抗菌的・審美的基質として、歯科療法で有望と考えられた。

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  • Enhanced flexibility and environmental durability of copper electrode produced with conductive ink containing silane coupling agents with diamine and ether spacer 査読

    Shintaro Sakurai, Takuma Uda, Hideya Kawasaki

    Journal of Materials Science: Materials in Electronics   2019年5月

  • Nanocomposite of N-doped Carbon Dots with Gold Nanoparticles for Visible Light Active Photosensitisers 査読

    T. Nozaki, T. Kakuta, Y. B. Pottathara, H. Kawasaki

    Photochemical & Photobiological Science   DOI: 10.1039/C9PP00035F   2019年2月

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  • A nanocomposite of N-doped carbon dots with gold nanoparticles for visible light active photosensitisers

    Nozaki, T., Kakuda, T., Pottathara, Y.B., Kawasaki, H.

    Photochemical and Photobiological Sciences   18 ( 5 )   2019年

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1039/c9pp00035f

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  • Enhanced photocatalytic activity of WO3 nanoparticles loaded with carbon 査読

    Ikrimah Aggita Basthiani, Hideya Kawasaki, Is Fatimah

    AIP Conference Proceedings   2026,020013   2018年10月

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  • Antibacterial Photocurable Acrylic Resin Coating Using a Conjugate between Silver Nanoclusters and Alkyl Quaternary Ammonium

    Chiaki Tominaga, Kanako Shitomi, Hirofumi Miyaji, Hideya Kawasaki

    ACS APPLIED NANO MATERIALS   1 ( 9 )   4809 - 4818   2018年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Ligand-protected silver nanoclusters (Ag NCs) have been gaining interest as antibacterial agents because of their ultrasmall sizes (<2 nm), their high antibacterial activity, and the variety of ligand species. The incorporation of Ag NCs into polymer resins is a desirable approach to achieve high durability and the long-term antibacterial activity of Ag NCs-based antibacterial coatings. However, the Ag NC-based antibacterial agents reported thus far are all water-soluble, and they have not been employed to generate antibacterial resins coatings because of the hydrophobic nature of the resins. Herein, we report for the first time Ag NC-based antibacterial photocurable acrylic resin coatings prepared by incorporating the conjugate of dihydrolipoic acid-capped Ag NCs with tetraoctylammonium (TOA) (TOA-Ag NCs). Given TOA's organosolubility, TOA-Ag NCs readily dissolved in the acrylic resin. The Ag NC-based antibacterial resin coatings displayed efficient antibacterial activity descending from the double antibacterial action of Ag NCs and TOA. This activity was maintained for a long time even after exposure of the coatings to aqueous environments. The cytotoxicity of the Ag NC-based antibacterial resin coatings was evaluated by measuring NIH3T3 cell proliferation and the expression of F-actin and vinculin, and data supported the low cytotoxicity of the coatings. These novel Ag NC-based antibacterial resin coatings have promising potential biomedical applications, for instance in healthcare/medical devices, for hospital infection prevention, and in implantable devices.

    DOI: 10.1021/acsanm.8b01010

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  • Filtration-induced production of conductive/robust Cu films on cellulose paper by low-temperature sintering in air conductive/robust Cu films on cellulose paper by low-temperature sintering in air 査読

    Shintaro Sakurai, Yusuke Akiyama, KAWASAKI,Hideya

    Royal Society Open Science   http://dx.doi.org/10.1098/rsos.172417   2018年7月

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  • Aggregation/Self-Assembly-Induced Approach for Efficient AuAg Bimetallic Nanocluster-Based Photosensitizers

    Daiki Hikosou, Sastoshi Saita, Saori Miyata, Hirofumi Miyaji, Tetsuya Furuike, Hiroshi Tamura, Hideya Kawasaki

    Journal of Physical Chemistry C   122 ( 23 )   12494 - 12501   2018年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society  

    Great efforts have been devoted to the exploration of potential diagnostic and therapeutic applications of thiolate-protected gold nanoclusters (Au NCs). One of the therapeutic applications is the photosensitized generation of highly reactive singlet oxygen (1O2) using Au NCs for photodynamic therapy. However, there is scope for improving the 1O2-generation efficiency of Au NC photosensitizers. In this study, we exploit three strategies to improve the 1O2-generation efficiency of glutathione-protected Au NCs: (i) doping with silver (i.e., using bimetallic AuAg NCs, (ii) achieving aggregation-induced emission (AIE) using a Au(I)-thiolate complex, and (iii) achieving self-assembly-induced emission (SAIE) using a polymer nanogel. The combination of these three effects dramatically increased the 1O2-generation efficiency and enhanced the luminescence of the glutathione-protected Au NCs, owing to the inhibition of the nonradiative decay pathways. Finally, the photosensitizers based on AuAg NC@nanogel composites were successfully used for antimicrobial photodynamic therapy (a-PDT) against oral bacteria. This study provides general insights into the molecular design of water-soluble Au NC photosensitizers for therapeutic applications.

    DOI: 10.1021/acs.jpcc.8b02373

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  • Label-free specific detection and collection of C-reactive protein using zwitterionic phosphorylcholine-polymer-protected magnetic nanoparticles 査読

    Sana Iwasaki, KAWASAKI,Hideya, Yasuhiko Iwasaki

    Langmuir   DOI: 10.1021/acs.langmuir.8b01007   2018年5月

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  • A Simple Method of Interpretating the Effects of Electric Charges on the Volume Phase Transition of Thermosensitive Gels 査読

    H. Maeda, S. Sasaki, 川崎 英也, R. Kakehashi

    gels   4, 24   2018年3月

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  • Solution Synthesis of N,N-Dimethylformamide-stabilized Iron Oxide Nanoparticles as an Efficient and Recyclable Catalyst for Alkene Hydrosilylation 査読

    R. Azuma, S. Nakamichi, J. Kimura, H.Yano, H.Kawasaki, T. Suzuki, R. Kondo, Y. Kanda, K. Shimizu, K. Kato, Y. Obora

    ChemCatChem   102378/cctc.201800161   2018年2月

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  • Bovine serum albumin-capped gold nanoclusters conjugating with methylene blue for efficient 1O2 generation via energy transfer. 国際誌

    Masaki Yamamoto, Kanako Shitomi, Saori Miyata, Hirofumi Miyaji, Hiroyuki Aota, Hideya Kawasaki

    Journal of colloid and interface science   510   221 - 227   2018年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Bovine serum albumin (BSA)-capped gold nanoclusters (BSA-Au NCs) are attractive photosensitizers for efficient singlet oxygen 1O2 generation owing to their high-water solubility, low toxicity, and the broad absorption from UV to visible wavelengths, and the long lifetime of the electronic excitations (of the order of microseconds). However, the 1O2 generation efficiency of BSA-Au NCs is relatively low. In the present study, a conjugate of BSA-Au NCs and methylene blue (MB) (BSA-Au NC-MB conjugate) has been developed to improve 1O2 generation for antimicrobial photodynamic therapy (aPDT). The BSA-Au NC-MB conjugate demonstrated enhanced 1O2 generation compared to the case of BSA-Au NCs and effective aPDT ability under white-light LED illumination for only 1min due to the resonance energy transfer from the Au NCs to the MB in the conjugate. To the best of my knowledge, this is first report of Au NCs on the resonance energy transfer application for efficient 1O2 generation. Therefore, the BSA-Au NC-MB conjugate is a novel photosensitizer for 1O2 generation that shows great potential for aPDT, and the present study also develops a very simple strategy to fabricate albumin-based nanoparticles for PDT.

    DOI: 10.1016/j.jcis.2017.09.011

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  • A simple way of interpretation of the effects of electric charges on the volume phase transition of thermosensitive gels 査読 国際誌

    Hiroshi Maeda, Shigeo Sasaki, Hideya Kawasaki, Rie Kakehashi

    gels   2018, 4(1), 24; doi: 10.3390/gels4010024 ( 1 )   2018年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.3390/gels4010024

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  • Ag7(MBISA)6 Nanoclusters Conjugated with Quinacrine for FRET-enhanced Photodynamic Activity under Visible Light Irradiation 査読

    C. Tominaga, D. Hikosou, I. Osaka, H. Kawasaki

    Acta Physico-Chimica Sinica   7805/PKU.WHXB201710271   2017年10月

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  • Quantum Dot-based Fluorescent Sensing

    Hideya Kawasaki

    ANALYTICAL SCIENCES   33 ( 9 )   987 - 988   2017年9月

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    記述言語:英語   出版者・発行元:JAPAN SOC ANALYTICAL CHEMISTRY  

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  • Antibacterial and cytotoxic effects of photoexcited Au clusters via blue high-power or white low-power light-emitting diode irradiation 査読

    S. Miyata, H.Miyaji, H.Kawasaki, E. Nishida, K. Shitomi, T.Akasaka, S. Tanaka, T.Iizuka, T. Sugaya

    Biol. Eng. Med.   2,1/BEM.1000126   2017年9月

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  • Cu-based composite inks of a self-reductive Cu complex with Cu flakes for the production of conductive Cu films on cellulose paper

    Yuki Kawaguchi, Yusuke Hotta, Hideya Kawasaki

    MATERIALS CHEMISTRY AND PHYSICS   197   87 - 93   2017年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE SA  

    Paper-based electronics have been attracting significant attention because of their inexpensive, renewable, and eco-friendly substrates. In this study, Cu-based composite inks composed of a copper-based metal-organic decomposition (MOD) ink and Cu flakes were prepared as precursors to obtain conductive Cu films on untreated cellulose paper. Copper-based MOD inks have not been explored for the production of conductive Cu films on cellulose paper because the properties of the paper, such as high porosity, high permeability, and surface roughness, are not favorable to obtain continuous conductive Cu films. However, using our method, we have obtained Cu films on paper with resistivities that are similar to 10 times lower than those of films on polyimide or glass substrates. Importantly, the Cu films on paper exhibited better mechanical resistance than those on a polyimide substrate, without any pre-treatment of the paper surface. (C) 2017 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.matchemphys.2017.05.017

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  • Contribution of Ligand Oxidation Products to High Durability of Copper Films Prepared from Low-Sintering-Temperature Copper Ink on Polymer Substrates

    Yusuke Akiyama, Tomonori Sugiyama, Hideya Kawasaki

    ADVANCED ENGINEERING MATERIALS   19 ( 8 )   2017年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    In electronic printing, ensuring high durability of sintered copper films on flexible substrates to obtain environmental stability and mechanical flexibility has become the most important task from a practical standpoint. In the study reported here, the authors develop solution synthesis of 2-amino-2-ethyl-1,3-propanediol (AEP)-protected copper nanoparticles (AEP-Cu NPs) with sizes of 3-8nm in ethylene glycol, where the Cu NPs are stabilized via the metallacyclic coordination stability of the AEP ligands. The sintered Cu film exhibits a resistivity of 50cm(-1) after heating at 150 degrees C under a nitrogen atmosphere. Most importantly, the resulting Cu films on the polyethylene terephthalate (PET) substrates show excellent durability in terms of bending and adhesion without requiring any additives like nanotubes and nanowires. Furthermore, the authors successfully demonstrated the high environmental stability of the resulting Cu film even after it is exposed to harsh environmental conditions (RH 80%, 60 degrees C) for 1 month. The environmental durability is further improved by utilizing a composite ink of AEP-Cu NPs with copper microflakes. It is experimentally proven that oxidation products from AEP ligands originating in the sintering process contributed to the high durability of sintered copper films on flexible substrates.

    DOI: 10.1002/adem.201700259

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  • Fabrication of Conductive Copper Films on Flexible Polymer Substrates by Low-temperature Sintering of Composite Cu Ink in Air 査読

    M. Kanzaki, Y. Kawaguchi, H. Kawasaki

    ACS Appl. Mater. Interfaces   9, 20852–20858   2017年7月

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  • Standard Denitions of Terms Relating to Mass Spectrometry 査読

    K. Iwamoto, T. Kinumi, K. Yoshino, Y. Naito, M. Kubota, H. Kawasaki

    J. Mass Spectrom. Soc. Jpn.   2, 76   2017年4月

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  • Preparation and use of DMF-stabilized iridium nanoclusters as methylation catalysts using methanol as the C1 source

    Kei Oikawa, Satoshi Itoh, Hiroki Yano, Hideya Kawasaki, Yasushi Obora

    CHEMICAL COMMUNICATIONS   53 ( 6 )   1080 - 1083   2017年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    We report methylations of alcohols and anilines catalyzed by DMFstabilized Ir nanoclusters using methanol as the C1 source. The DMFstabilized Ir nanoclusters were prepared in one step and have diameters of 1-1.5 nm. They react in a borrowing-hydrogen reaction and are efficient methylation catalysts (TON up to 310000).

    DOI: 10.1039/c6cc09279a

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  • Aluminum Foil Suitable for Laser Desorption/Ionization Mass Spectrometry of Fullerene 査読

    H. Kawasaki, M. Moriyama, R. Arakawa

    Sci. Technol. Reports   in press   2017年

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  • Assessment of antimicrobial and biocompatible effects of Au25(Capt)18 clusters photoexcited by blue LED 査読

    12   2703 - 2716   2017年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Effective removal of surface-bound cetyltrimethylammonium ions from thiolmonolayer- protected Au nanorods by treatment with dimethyl sulfoxide/citric acid

    Keisuke Nishida, Hideya Kawasaki

    RSC ADVANCES   7 ( 29 )   18041 - 18045   2017年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    Cetyltrimethylammonium bromide (CTAB)-based surfactants are typically used as morphology-directing/stabilising agents for gold nanorods (AuNRs), forming bilayers on their surface. However, the biological applications of AuNRs require the removal of surface-bound CTAB due its high toxicity and the poor colloidal stability of CTAB-covered AuNRs in biological media. Herein, we report a simple and effective strategy for removing surface-bound cetyltrimethylammonium (CTA) cations from poly(ethylene glycol) thiolate-protected AuNRs (PEG-AuNRs) by treatment with dimethyl sulfoxide/citric acid (DMSO/Cit), achieving residual CTA ion levels that cannot be detected by highly sensitive mass spectrometry or X-ray photoelectron spectroscopy (XPS) techniques. The DMSO/Cit treatment is thought to destabilise the Ag-Br-CTA complex on AuNRs, since citric acid forms strongly bound chelate complexes with CTA cations.

    DOI: 10.1039/c7ra02179h

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  • Antimicrobial photodynamic activity and cytocompatibility of Au25(Capt)18 clusters photoexcited by blue LED light irradiation. 国際誌

    Saori Miyata, Hirofumi Miyaji, Hideya Kawasaki, Masaki Yamamoto, Erika Nishida, Hiroko Takita, Tsukasa Akasaka, Natsumi Ushijima, Toshihiko Iwanaga, Tsutomu Sugaya

    International journal of nanomedicine   12   2703 - 2716   2017年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Antimicrobial photodynamic therapy (aPDT) has beneficial effects in dental treatment. We applied captopril-protected gold (Au25(Capt)18) clusters as a novel photosensitizer for aPDT. Photoexcited Au clusters under light irradiation generated singlet oxygen (1O2). Accordingly, the antimicrobial and cytotoxic effects of Au25(Capt)18 clusters under dental blue light-emitting diode (LED) irradiation were evaluated. 1O2 generation of Au25(Capt)18 clusters under blue LED irradiation (420-460 nm) was detected by a methotrexate (MTX) probe. The antimicrobial effects of photoexcited Au clusters (0, 5, 50, and 500 μg/mL) on oral bacterial cells, such as Streptococcus mutans, Aggregatibacter actinomycetemcomitans, and Porphyromonas gingivalis, were assessed by morphological observations and bacterial growth experiments. Cytotoxicity testing of Au clusters and blue LED irradiation was then performed against NIH3T3 and MC3T3-E1 cells. In addition, the biological performance of Au clusters (500 μg/mL) was compared to an organic dye photosensitizer, methylene blue (MB; 10 and 100 μg/mL). We confirmed the 1O2 generation ability of Au25(Capt)18 clusters through the fluorescence spectra of oxidized MTX. Successful application of photoexcited Au clusters to aPDT was demonstrated by dose-dependent decreases in the turbidity of oral bacterial cells. Morphological observation revealed that application of Au clusters stimulated destruction of bacterial cell walls and inhibited biofilm formation. Aggregation of Au clusters around bacterial cells was fluorescently observed. However, photoexcited Au clusters did not negatively affect the adhesion, spreading, and proliferation of mammalian cells, particularly at lower doses. In addition, application of Au clusters demonstrated significantly better cytocompatibility compared to MB. We found that a combination of Au25(Capt)18 clusters and blue LED irradiation exhibited good antimicrobial effects through 1O2 generation and biosafe characteristics, which is desirable for aPDT in dentistry.

    DOI: 10.2147/IJN.S131602

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  • Thiolate-protected Gold Nanoclusters Au-25(phenylethanethiol)(18): An Efficient Catalyst for the Synthesis of Propargylamines from Aldehydes, Amines, and Alkynes

    Yurina Adachi, Hideya Kawasaki, Tatsuki Nagata, Yasushi Obora

    CHEMISTRY LETTERS   45 ( 12 )   1457 - 1459   2016年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHEMICAL SOC JAPAN  

    In this study, we report a thiolate-protected Au nanocluster, Au-25(phenylethanethiol)(18) [Au-25(PET)(18)], which serves as an efficient catalyst by a three-component coupling reaction (A(3) reaction) of aldehydes, amines, and alkynes to give the corresponding propargylamines in good to excellent yields.

    DOI: 10.1246/cl.160813

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  • Effects of ligand species and cluster size of biomolecule-protected Au nanoclusters on efficiency of singlet-oxygen generation

    Masaki Yamamoto, Issey Osaka, Kazuko Yamashita, Hiromi Hasegawa, Ryuichi Arakawa, Hideya Kawasaki

    JOURNAL OF LUMINESCENCE   180   315 - 320   2016年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Thiolate-protected Au-25 nanoclusters (NCs) have been shown to be efficient O-1(2) photosensitizers. The O-1(2)-generation efficiency of thiolate-protected Au NCs is expected to depend on the thiolate ligand species and size of the gold clusters. In the present study, Au25(glutathione)18 nanoclusters (Au-25(SG)(18) NCs) and bovine-serum-albumin (BSA)-protected Au-25 nanoclusters (BSA-Au-25 NCs) were synthesized to investigate the effect of different thiolate ligands on the O-1(2) generation. The efficiency of O-1(2) generation by the Au-25 NCs that were photo-excited at 532 nm was evaluated with methotrexate as a chemical probe. The effect of Au NC size on the O-1(2)-generation efficiency of thiolate-protected Au-18 and Au-25 NCs was also investigated. The O-1(2)-generation efficiency of BSA-Au25 NCs was higher than that of Au-25(SG)(18) NCs. The long lifetime of the electronic excitations and the high-photo-stability were key factors facilitating the formation of O-1(2) in BSA-Au-25 NCs. The effect of Au NC size on the O-1(2)-generation efficiency of thiolate-protected Au NCs, Au-n(SR)(m), decreased in the following order: Au-25(SR)(18) &gt; Au-18(SR)(14). (C) 2016 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jlumin.2016.08.059

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  • High molecular weight organic compounds (HMW-OCs) in severe winter haze: Direct observation and insights on the formation mechanism

    F. K. Duan, K. B. He, Y. L. Ma, T. Ihozaki, H. Kawasaki, R. Arakawa, S. Kitayama, K. Tujimoto, T. Huang, T. Kimoto, H. Furutani, M. Toyoda

    ENVIRONMENTAL POLLUTION   218   289 - 296   2016年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCI LTD  

    High molecular weight organic compounds (HMW-OCs), formed as secondary organic aerosols (SOA), have been reported in many laboratory studies. However, little evidence of HMW-OCs formation, in particular during winter season in the real atmosphere, has been reported. In January 2013, Beijing faced historically severe haze pollution, in which the hourly PM2.5 concentration reached as high as 974 mu g m(-3). Four typical haze events (HE1 to HE4) were identified, and HE2 (Jan. 9-16) was the most serious of these. Based on the hourly observed chemical composition of PM2.5 and the daily organic composition analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), we found that abundant ion peaks in m/z 200-850 appeared on heavy haze days, whereas these were negligible on a clear day, indicating the existence of HMW-OCs in the wintertime haze. A negative nonlinear correlation between HMW-OCs and 03 suggested that gas oxidation was not likely to be the dominant mechanism for HMW-OCs formation. During the heavy haze events, the relative humidity and mass ratio of H2O/PM2.5 reached as high as 80% and 0.2, respectively. The high water content and its good positive correlation with HMW-OCs indicated that an aqueous-phase process may be a significant pathway in wintertime. The evidence that acidity was much higher during HE2 (0.37 mu g m(-3)) than on other days, as well as its strong correlation with HMW-OCs, indicated that acid catalyzed reactions likely resulted in HMW-OCs formation during the heavy winter haze in Beijing. (C) 2016 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.envpol.2016.07.004

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  • Low-temperature sintering of metallacyclic stabilized copper nanoparticles and adhesion enhancement of conductive copper film to a polyimide substrate

    Tomonori Sugiyama, Mai Kanzaki, Ryuichi Arakawa, Hideya Kawasaki

    JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS   27 ( 7 )   7540 - 7547   2016年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    We report that both low electric resistivity and strong adhesion to polyimide film were attained for a conductive Cu film prepared by low-temperature sintering of 2-amino-1-butanol-protected Cu nanoparticles (AB-Cu NPs) with an average size of 4.4 nm. The sintering temperature of 60 A degrees C for the AB-Cu NPs is the lowest ever reported for Cu NPs. A nanoink comprising these AB-Cu NPs (similar to 35 wt% Cu) produced a conductive Cu film with resistivity of 52 mu Omega cm after heating at 150 A degrees C under a nitrogen flow. The adhesion to a polyimide film was compared for films prepared from nanoinks consisting of three different types of alkanol-amine-based Cu NPs: AB-Cu NPs, 1-amino-2-propanol-Cu NPs, and 3-amino-1-propanol-Cu NPs. Only the Cu film prepared from the AB-Cu nanoink established strong adhesion to the substrate without decreasing the electrical conductivity. The adhesiveness is attributed to residual oxidation products after thermal sintering of the Cu nanoinks.

    DOI: 10.1007/s10854-016-4734-8

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  • Direct Imaging Mass Spectrometry of Plant Leaves Using Surface-assisted Laser Desorption/Ionization with Sputter deposited Platinum Film

    Tomoyuki Ozawa, Issey Osaka, Satoshi Hamada, Tatsuya Murakami, Akio Miyazato, Hideya Kawasaki, Ryuichi Arakawa

    ANALYTICAL SCIENCES   32 ( 5 )   587 - 591   2016年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC ANALYTICAL CHEMISTRY  

    Plant leaves administered with systemic insecticides as agricultural chemicals were analyzed using imaging mass spectrometry (IMS). Matrix-assisted laser desorption/ionization (MALDI) is inadequate for the detection of insecticides on leaves because of the charge-up effect that occurs on the non-conductive surface of the leaves. In this study, surface assisted laser desorption/ionization with a sputter-deposited platinum film (Pt-SALDI) was used for direct analysis of chemicals in plant leaves. Sputter-deposited platinum (Pt) films were prepared on leaves administered with the insecticides. A sputter-deposited Pt film with porous structure was used as the matrix for Pt-SALDI. Acephate and acetamiprid contained in the insecticides on the leaves could be detected using Pt-SALDI-MS, but these chemical components could not be adequately detected using MALDI-MS because of the charge-up effect. Enhancement of ion yields for the insecticides was achieved using Pt-SALDI, accompanied by prevention of the charge-up effect by the conductive Pt film. The movement of systemic insecticides in plants could be observed clearly using Pt-SALDI-IMS. The distribution and movement of components of systemic insecticides on leaves could be analyzed directly using Pt-SALDI-IMS. Additionally, changes in the properties of the chemicals with time, as an indicator of the permeability of the insecticides, could be evaluated.

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  • Characterization of Chemical Species in Lanthanide (III)-Alizarin Complexone (ALC)-Fluoride Solution Using ESI-MS

    Kazuko Yamashita, Tatsuo Nakada, Hideya Kawasaki, Ryuichi Arakawa

    BUNSEKI KAGAKU   65 ( 1 )   39 - 43   2016年1月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC ANALYTICAL CHEMISTRY  

    The method for the quantitative analysis of fluoride anion employs a color change from purple-red to violet under the reaction of La(III)-alizarin-complexone(ALC) with the fluoride anion. We investigated the chemical species in a La(III)-alizarin-complexone(ALC) solution as well as its reaction solution with fluoride anion by using high-resolution mass spectrometry. As a result, the complexes present in a La(III)-(ALC) solution were estimated to be (La-ALC)(4-6), and their structure was an annulation consisting of (La-ALC) units. In these three complexes, only the (La-ALC)(4) complex reacted with fluorine ions to produce deprotonated complexes of [(La-ALC)(4)-H + LaF2] and [(La-ALC)(4)-2H + LaF]. This deprotonation of (La-ALC)(4) caused the solution to vary from purple-red to violet. (La-ALC)(5-6) complexes were not detected in a solution with excessive fluorine ions. This is because (La-ALC)(4) decreasing with complexation with the fluorine ions is thought to be supplied from the degradation of (La-ALC)(5-6). The same results were obtained in the system of Ce(III).

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  • Formate-free metal-organic decomposition inks of copper particles and self-reductive copper complex for the fabrication of conductive copper films 査読

    Y. Kawaguchi, R. Arakawa, H. Kawasaki

    Journal of Coating Science and Technology   3, 56-61   2016年

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  • Reduced Sampling Size with Nanopipette for Tapping-Mode Scanning Probe Electrospray Ionization Mass Spectrometry Imaging 査読

    T. Kohigashi, Y. Otsuka, R. Shimazu1, T. Matsumoto, F. Iwata, H. Kawasaki, and R. Arakawa, H. Kawasaki, R. Arakawa

    Mass Spectrometry   5, S0054 ( 2 )   S0054 - S0054   2016年

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    記述言語:英語   出版者・発行元:一般社団法人 日本質量分析学会  

    <p>Mass spectrometry imaging (MSI) with ambient sampling and ionization can rapidly and easily capture the distribution of chemical components in a solid sample. Because the spatial resolution of MSI is limited by the size of the sampling area, reducing sampling size is an important goal for high resolution MSI. Here, we report the first use of a nanopipette for sampling and ionization by tapping-mode scanning probe electrospray ionization (t-SPESI). The spot size of the sampling area of a dye molecular film on a glass substrate was decreased to 6 μm on average by using a nanopipette. On the other hand, ionization efficiency increased with decreasing solvent flow rate. Our results indicate the compatibility between a reduced sampling area and the ionization efficiency using a nanopipette. MSI of micropatterns of ink on a glass and a polymer substrate were also demonstrated.</p>

    DOI: 10.5702/massspectrometry.S0054

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  • UV photo-mediated size-focusing synthesis of silver nanoclusters

    C. Tominaga, H. Hasegawa, K. Yamashita, R. Arakawa, H. Kawasaki

    RSC ADVANCES   6 ( 77 )   73600 - 73604   2016年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    In this work, we first report the photo-mediated size-focusing synthesis of glutathione (SG)-protected atomically precise Ag nanoclusters (Ag NCs). This photo-mediated size-focusing synthesis comprises a two-step protocol: (i) the reduction of Ag ions by NaBH4 to form polydisperse Ag NC intermediates and (ii) the subsequent photo-mediated size-focusing of these intermediates under 365 nm UV irradiation, producing monodisperse Ag-32(SG)(19) NCs. The role of light in the size-focusing synthesis of Ag NCs was investigated. We have demonstrated that 365 nm UV light irradiation under air/O-2 is an important parameter for the synthesis of well-defined Ag NCs via the photo-mediated size-focusing process due to the UV light/oxygen-sensitive properties of Ag.

    DOI: 10.1039/c6ra10892j

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  • Identification of Anthropogenic Compounds in Urban Environments and Evaluation of Automated Methods for Reading Fragmentation-A Case of River Water 査読

    A. Yamamoto, N. Matsumoto, H. Kawasaki, R. Arakawa

    Mass Spectrom   5(1), A0045   2016年

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  • Thiolated-2-methacryloyloxyethyl phosphorylcholine protected silver nanoparticles as novel photo-induced cell-killing agents.

    Sangsuwan, Arunee, Kawasaki, Hideya, Iwasaki, Yasuhiko

    Colloids and surfaces. B, Biointerfaces   140   2016年

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.colsurfb.2015.12.037

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  • Antimicrobial Silver Nanoclusters Bearing Biocompatible Phosphorylcholine-Based Zwitterionic Protection

    Sangsuwan, Arunee, Kawasaki, Hideya, Matsumura, Yoshinobu, Iwasaki, Yasuhiko

    Bioconjugate Chemistry   27 ( 10 )   2016年

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/acs.bioconjchem.6b00455

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  • Silver nanoparticle functionalized glass fibers for combined surface-enhanced Raman scattering spectroscopy (SERS)/surface-assisted laser desorption/ionization (SALDI) mass spectrometry via plasmonic/thermal hot spots

    Masahiro Kurita, Ryuichi Arakawa, Hideya Kawasaki

    ANALYST   141 ( 20 )   5835 - 5841   2016年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    We presented the fabrication of a silver nanoparticle (Ag NP) functionalized glass fiber (Ag-GF) substrate for combined surface-enhanced Raman scattering spectroscopy (SERS)/surface-assisted laser desorption/ ionization (SALDI) mass spectrometry. Ag NPs were immobilized onto the surface of glass fibers through a simple sputter deposition process. The SERS and SALDI activities strongly depended on the nanostructures of the deposited Ag NPs on the GFs. The closely-packed Ag NPs with a size of 20-50 nm and an inter-particle nanoscale gap of less than 10 nm were effective for the simultaneously enhanced SERS/SALDI substrate via plasmonic/thermal "hot spots", while the interconnected continuous Ag film reduced both the SERS/SALDI activities. The SERS enhanced factor (EFSERS) and SALDI enhanced factor (EFSALDI) were newly proposed. Finally, the concentration-dependent signal intensities of SERS and SALD-MS of sulfur compounds using an identical Ag NP-GF substrate were examined, and the linear dependence relationship in the log-log plot was demonstrated for the combined quantitative SERS/SALDI-MS analysis.

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  • Simultaneous detection of phosphatidylcholines and glycerolipids using matrix-enhanced surface-assisted laser desorption/ionization-mass spectrometry with sputter-deposited platinum film

    Tomoyuki Ozawa, Issey Osaka, Taisuke Ihozaki, Satoshi Hamada, Yusuke Kuroda, Tatsuya Murakami, Akio Miyazato, Hideya Kawasaki, Ryuichi Arakawa

    JOURNAL OF MASS SPECTROMETRY   50 ( 11 )   1264 - 1269   2015年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-BLACKWELL  

    Matrix-assisted laser desorption/ionisation (MALDI) imaging mass spectrometry (IMS) allows for the simultaneous detection and imaging of several molecules in brain tissue. However, the detection of glycerolipids such as diacylglycerol (DAG) and triacylglycerol (TAG) in brain tissues is hindered in MALDI-IMS because of the ion suppression effect from excessive ion yields of phosphatidylcholine (PC). In this study, we describe an approach that employs a homogeneously deposited metal nanoparticle layer (or film) for the detection of glycerolipids in rat brain tissue sections using IMS. Surface-assisted laser desorption/ionisation IMS with sputter-deposited Pt film (Pt-SALDI-IMS) for lipid analysis was performed as a solvent-free and organic matrix-free method. Pt-SALDI produced a homogenous layer of nanoparticles over the surface of the rat brain tissue section. Highly selective detection of lipids was possible by MALDI-IMS and Pt-SALDI-IMS; MALDI-IMS detected the dominant ion peak of PC in the tissue section, and there were no ion peaks representing glycerolipids such as DAG and TAG. In contrast, Pt-SALDI-IMS allowed the detection of these glycerolipids, but not PC. Therefore, using a hybrid method combining MALDI and Pt-SALDI (i.e., matrix-enhanced [ME]-Pt-SALDI-IMS), we achieved the simultaneous detection of PC, PE and DAG in rat brain tissue sections, and the sensitivity for the detection of these molecules was better than that of MALDI-IMS or Pt-SALDI alone. The present simple ME-Pt-SALDI approach for the simultaneous detection of PC and DAG using two matrices (sputter-deposited Pt film and DHB matrix) would be useful in imaging analyses of biological tissue sections. Copyright (c) 2015 John Wiley & Sons, Ltd.

    DOI: 10.1002/jms.3700

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  • High-Concentration Synthesis of Sub-10-nm Copper Nanoparticles for Application to Conductive Nanoinks

    Yuki Hokita, Mai Kanzaki, Tomonori Sugiyama, Ryuichi Arakawa, Hideya Kawasaki

    ACS APPLIED MATERIALS & INTERFACES   7 ( 34 )   19382 - 19389   2015年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    A simple, high-concentration (up to 0.6 M Cu salt) synthesis of sub-10-nm copper nanopartides (Cu NPs) was developed in ethylene glycol at room temperature under ambient air conditions using 1-amino-2-propanol (AmIP) as the stabilizer. Monodispersed AmIP-Cu NPs of 3.5 +/- 1.0 nm were synthesized in a high yield of similar to 90%. Thus, nearly 1 g of sub-10-nm Cu NP powder was obtained using a one-step synthesis for the first time. It is proposed that metallacyclic coordination stability of a five-membered ring type between the Cu and AmIP causes the high binding force of Am IP onto the Cu surface, resulting in the superior stability of the AmIP-Cu NPs in a solution. The purified powder of AmIP-Cu NPs can be redispersed in alcohol-based solvents up to high Cu contents of 45 wt % for the preparation of Cu nanoink. The resistivity of the conductive Cu film obtained from the Cu nanoink was 30 mu Omega. cm after thermal heating at 150 degrees C for 15 min under a nitrogen flow. The long-term resistance stability of the Cu film under an air atmosphere was also demonstrated.

    DOI: 10.1021/acsami.5b05542

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  • Synthesis of binary solid solution Cu-Pd nanoparticles by DMF reduction for enhanced photoluminescence properties

    Masashi Chiba, Mai Nguyen Thanh, Yasuchika Hasegawa, Yasushi Obora, Hideya Kawasaki, Tetsu Yonezawa

    JOURNAL OF MATERIALS CHEMISTRY C   3 ( 3 )   514 - 520   2015年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    We report the use of a DMF reduction method for straightforward synthesis of binary solid solution Cu-Pd nanoparticles (NPs) over the entire range of composition. The resulting NPs were uniform in size (less than 2.5 nm), tunable in composition, and exhibited photoluminescence properties that were nonlinear in composition. These binary solid solution NPs showed enhanced photoluminescence intensity and quantum yield compared to those of the single-metal NPs and their mixtures. The highest quantum yield of 3.10% for Cu-Pd alloy NPs synthesized using equimolar feeding ratio versus 2.75% for Cu and 0.71% for Pd NPs was obtained. These enhancements make the alloy NPs promising materials for optical applications.

    DOI: 10.1039/c4tc02129k

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  • Optical Properties of 2-Methacryloyloxyethyl Phosphorylcholine-Protected Au-4 Nanoclusters and Their Fluorescence Sensing of C-Reactive Protein

    Yoshimoto, Junya, Sangsuwan, Arunee, Osaka, Issey, Yamashita, Kazuko, Iwasaki, Yasuhiko, Inada, Mitsuru, Arakawa, Ryuichi, Kawasaki, Hideya

    Journal of Physical Chemistry C   119 ( 25 )   2015年

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/acs.jpcc.5b03934

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  • Chemical modification of amino acids by atmospheric-pressure cold plasma in aqueous solution

    Eisuke Takai, Tsuyoshi Kitamura, Junpei Kuwabara, Satoshi Ikawa, Shunsuke Yoshizawa, Kentaro Shiraki, Hideya Kawasaki, Ryuichi Arakawa, Katsuhisa Kitano

    JOURNAL OF PHYSICS D-APPLIED PHYSICS   47 ( 28 )   2014年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    Plasma medicine is an attractive new research area, but the principles of plasma modification of biomolecules in aqueous solution remain elusive. In this study, we investigated the chemical effects of atmospheric-pressure cold plasma on 20 naturally occurring amino acids in aqueous solution. High-resolution mass spectrometry revealed that chemical modifications of 14 amino acids were observed after plasma treatment: (i) hydroxylation and nitration of aromatic rings in tyrosine, phenylalanine and tryptophan; (ii) sulfonation and disulfide linkage formation of thiol groups in cysteine; (iii) sulfoxidation of methionine and (iv) amidation and ring-opening of five-membered rings in histidine and proline. A competitive reaction experiment using 20 amino acids demonstrated that sulfur-containing and aromatic amino acids were preferentially decreased by the plasma treatment. These data provide fundamental information for elucidating the mechanism of protein inactivation for biomedical plasma applications.

    DOI: 10.1088/0022-3727/47/28/285403

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  • Use of high-resolution mass spectrometry to identify precursors and biodegradation products of perfluorinated and polyfluorinated compounds in end-user products

    Atsushi Yamamoto, Hirotaka Hisatomi, Tomoshige Ando, Shusuke Takemine, Tomoko Terao, Toshiki Tojo, Masahiro Yagi, Daisuke Ono, Hideya Kawasaki, Ryuichi Arakawa

    ANALYTICAL AND BIOANALYTICAL CHEMISTRY   406 ( 19 )   4745 - 4755   2014年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER HEIDELBERG  

    Structural identification of perfluoroalkyl and polyfluoroalkyl substances found in end-user products and their biodegradation products was performed using ultra-high resolution mass spectrometry. Little attention has so far been paid to the environmental burden of perfluorooctane sulfonate and perfluorooctanoic acid from compounds with a molar mass of similar to 2,000. Analysis of end-user waterproofing and stain repellent products revealed the presence of numerous ions with molar masses ranging from 1,000 to 2,000 and complex mass spectra. Ultra-high resolution mass spectrometry determined the accurate mass of the observed ions, allowing the cleavage position and fragment structure to be determined. The precursor structures were determined based on reconstitution of the retrieved fragments. Products of fluorochemical manufacturers before voluntary regulation comprised compounds with plural perfluorooctyl chains. In the current product lines, compounds comprising perfluorobutyl chains were detected. Biodegradation tests using activated sludge revealed that biodegradation products consistent with those reported previously were generated even from complex end-user products. For example, the biodegradation test revealed the formation of N-ethyl perfluorooctane sulfonamido acetic acid and various fluorotelomer acids in the samples. The results of the present study suggest that the environmental burden of these compounds should be reevaluated.

    DOI: 10.1007/s00216-014-7862-0

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  • Gold-Decorated Titania Nanotube Arrays as Dual-Functional Platform for Surface-Enhanced Raman Spectroscopy and Surface-Assisted Laser Desorption/Ionization Mass Spectrometry

    Syuhei Nitta, Atsushi Yamamoto, Masahiro Kurita, Ryuichi Arakawa, Hideya Kawasaki

    ACS APPLIED MATERIALS & INTERFACES   6 ( 11 )   8387 - 8395   2014年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    In this report, we demonstrate gold-decorated titania nanotube arrays (Au-TNA substrate) as a dual-functional platform for surface-enhanced Raman spectroscopy (SERS) and surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). The Au nanopartides are grown on the substrate using vapor deposition of Au. The resulting substrates perform better than Au colloids in terms of the reproducibility of the SEAS measurements, long-term stability of the fabricated structures, and clean surface of the Au. The nanostructure of the Au-TNA substrate was designed to optimize the SALDI-MS and SERS performance. Excellent reproducibility of the SERS measurements using the Au-TNA substrate was obtained, with a standard error less than 6 %. SALDI activity was also demonstrated for the same Au-TNA substrates. Finally, the Au-TNA substrate was used for combined SERS and SALDI-MS analysis (i) to discriminate the structural isomers of pyridine compounds (para-, meta-, and ortho-pyridinecarboxylic acid) and (ii) to detect polycarbamate, a dithiocarbamate fungicide. These results are difficult to obtain using either approach alone.

    DOI: 10.1021/am501291d

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  • Microwave-assisted Synthesis of Near-infrared-luminescent Ovalbumin-protected Gold Nanoparticles as a Luminescent Glucose Sensor

    Junya Yoshimoto, Naoki Tanaka, Mitsuru Inada, Ryuichi Arakawa, Hideya Kawasaki

    CHEMISTRY LETTERS   43 ( 6 )   793 - 795   2014年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHEMICAL SOC JAPAN  

    In this work, highly luminescent ovalbumin-protected Au nanoparticles (OVA-Au NPs) with a quantum yield of 9.3% for emission at 645 nm were demonstrated as a fluorescence probe for sensitive detection of glucose. The fluorescence of the Au NPs originated from the Au(I)-thiol (S) complex on their surfaces, and it was found to be quenched effectively by enzymatically generated hydrogen peroxide (H2O2). The OVA-Au NPs allowed the determination of glucose concentrations in the range varying from 1.0 x 10(-4) to 1 x 10(-2) M with a detection limit of 1 x 10(-5) M.

    DOI: 10.1246/cl.140126

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  • Laser desorption/ionization mass spectrometry (LDI-MS) of lipids with iron oxide nanoparticle-coated targets 査読

    M. Kusano, S. Kawabata, Y. Tamura, D. Mizoguchi, M. Murouchi, H. Kawasaki, R. Arakawa, K. Tanaka

    Mass Spectrometry   Vol. 3 (2014), A0026 ( 1 )   A0026 - A0026   2014年1月

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    記述言語:英語   出版者・発行元:一般社団法人 日本質量分析学会  

    Iron oxide nanoparticle (NP)-coated target plates were employed for the direct detection and analysis of low molecular weight lipids by laser desorption/ionization (LDI) mass spectrometry (MS). We have demonstrated that the use of the iron oxide NP-coated target provides a simple, direct, and rapid detection method for lipid standards and epidermal surface lipids without any cumbersome sample pretreatment as well as mass spectra that are free of background matrix peaks. Lipid standards (1-stearoyl-<i>sn</i>-glycero-3-phosphocholine, 1,2-dioleoyl-<i>sn</i>-glycerol, 1-palmitoyl-2-oleoyl-3-linoleoyl-<i>rac</i>-glycerol, 1,2-distearoyl-<i>sn</i>-glycero-3-phosphocholine) were detected as either protonated or cationated species. Clean MS/MS spectra for each lipid were also successfully obtained. Pre-MS surface cleaning of the target plates with UV-ozone treatment successfully removed organic contaminants that would interfere with the mass spectra especially in the low molecular weight region. Preliminary application of the presented target plate to the detection of endogenous lipids in latent fingerprints showed promising results and for potential use in the visualization and chemical composition determination of latent fingerprints by nanoparticle assistance.

    DOI: 10.5702/massspectrometry.A0026

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  • Label-free detection of C-reactive protein using highly dispersible gold nanoparticles synthesized by reducible biomimetic block copolymers

    Iwasaki, Yasuhiko, Kimura, Toshihiro, Orisaka, Masaki, Kawasaki, Hideya, Goda, Tatsuro, Yusa, Shin-ichi

    Chemical Communications   50 ( 42 )   2014年

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1039/c4cc01855a

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  • Generation of Singlet Oxygen by Photoexcited Au-25(SR)(18) Clusters

    Kawasaki, Hideya, Kumar, Santosh, Li, Gao, Zeng, Chenjie, Kauffman, Douglas R., Yoshimoto, Junya, Iwasaki, Yasuhiko, Jin, Rongchao

    Chemistry of Materials   26 ( 9 )   2014年

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/cm500260z

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  • Application of Tapping-Mode Scanning Probe Electrospray Ionization to Mass Spectrometry Imaging of Additives in Polymer Films, 査読

    R. Shimazu, Y. Yamoto, T. Kosaka, H. Kawasaki, R. Arakawa

    Mass Spectrometry   3, S0050(Page 1 of 7) ( 3 )   S0050 - S0050   2014年

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    記述言語:英語   出版者・発行元:一般社団法人 日本質量分析学会  

    We report the application of tapping-mode scanning probe electrospray ionization (t-SPESI) to mass spectrometry imaging of industrial materials. The t-SPESI parameters including tapping solvent composition, solvent flow rate, number of tapping at each spot, and step-size were optimized using a quadrupole mass spectrometer to improve mass spectrometry (MS) imaging of thin-layer chromatography (TLC) and additives in polymer films. Spatial resolution of approximately 100 μm was achieved by t-SPESI imaging mass spectrometry using a fused-silica capillary (50 μm i.d., 150 μm o.d.) with the flow rate set at 0.2 μL/min. This allowed us to obtain discriminable MS imaging profiles of three dyes separated by TLC and the additive stripe pattern of a PMMA model film depleted by UV irradiation.

    DOI: 10.5702/massspectrometry.S0050

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  • Sensitive Detection of Aromatic Hydrophobic Compounds in Water and Perfluorooctane Sulfonate in Human Serum by Surface-assisted Laser Desorption/Ionization Mass Spectrometry (SALDI-MS) with Amine Functionalized Graphene-coated Cobalt Nanoparticles, 査読

    K. Nakai, H. Kawasaki, A.Yamamoto, R. Arakawa, R. N. Grass, W. J. Stark,

    Mass Spectrometry, 3,   3, A0028 ( 4 )   1 - 5   2014年

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    記述言語:英語   出版者・発行元:日本質量分析学会  

    DOI: 10.5702/massspectrometry.A0028

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  • Stable Au25(SR)18/TiO2 Composite Nanostructure with Enhanced Visible Light Photocatalytic Activity 査読

    Y. Changlin, L. Gao, S. Kumar, H. Kawasaki, J. Rongchao

    J. Phys. Chem. Lett.   4, 2847–2852   2013年8月

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  • 低温焼結・導電性ペースト材料への応用に向けた銅ナノ粒子の保護剤フリー溶液合成

    川崎 英也, 大洞 康嗣, 米澤 徹, 荒川 隆一

    日本接着学会誌 = Journal of the Adhesion Society of Japan   49 ( 5 )   171 - 176   2013年5月

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    記述言語:日本語   出版者・発行元:一般社団法人 日本接着学会  

    DOI: 10.11618/adhesion.49.171

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  • Two-dimensional Mapping Using Different Chromatographic Separations Coupled with Mass Spectrometry for the Analysis of Ginsenosides in Panax Ginseng Root and Callus

    Issey Osaka, Hirotaka Hisatomi, Yumiko Ueno, Shu Taira, Yuko Sahashi, Hideya Kawasaki, Ryuichi Arakawa

    ANALYTICAL SCIENCES   29 ( 4 )   429 - 434   2013年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC ANALYTICAL CHEMISTRY  

    Two-dimensional (2D) mapping using different chromatographic separations coupled with mass spectrometry is a rapid and simple method for the analysis of a mixture using conventional liquid chromatography mass spectrometry. The 2D map could be created from two different chromatograms obtained with the same detector and different columns or separation methods. In this study, 2D mapping was applied to the analysis of components contained in Panax ginseng, and was evaluated in terms of its effectiveness in the separation of these components. The several glycosides included in Panax ginseng could not be sufficiently separated by one-dimensional chromatography with a reverse phase or a hydrophilic interaction chromatography (HILIC) column, but the components of Panax ginseng could be separated and visualized as a component pattern by 2D mapping. We showed that the components contained in the calli and their quantities were altered by the culture conditions in which the calli were grown by 2D mapping. 2D mapping is expected to be a useful method for visualizing complex component patterns found in glycosides and unknown compounds in foods.

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  • Surfactant-Free Solution-Based Synthesis of Metallic Nanoparticles Toward Efficient Use of the Nanoparticles’ Surfaces and Their Application in Catalysis and Chemo-/Biosensing 査読

    H. Kawasaki

    Nanotechnology Reviews   2, 5-25   2013年1月

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  • Suitability of GaP nanoparticles as a surface-assisted laser desorption/ionization mass spectroscopy inorganic matrix and their soft ionization ability

    Tetsu Yonezawa, Hiroki Tsukamoto, Shinji Hayashi, Yuki Myojin, Hideya Kawasaki, Ryuichi Arakawa

    ANALYST   138 ( 4 )   995 - 999   2013年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    Surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF-MS) using GaP nanoparticles (NPs) prepared by a gas evaporation method was investigated on poly(ethylene glycol)s (PEGs). The mass spectra of PEG and survival yield measurements suggested that larger GaP NPs have a quite high soft ionization ability.

    DOI: 10.1039/c2an36738f

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  • A thiophene-containing compound as a matrix for matrix-assisted laser desorption/ionization mass spectrometry and the electrical conductivity of matrix crystals

    Akikazu Yasuda, Takayuki Ishimaru, Shogo Nishihara, Masamichi Sakai, Hideya Kawasaki, Ryuichi Arakawa, Yasushi Shigeri

    EUROPEAN JOURNAL OF MASS SPECTROMETRY   19 ( 1 )   29 - 37   2013年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IM PUBLICATIONS  

    The electrical conductivity of the matrix crystal might be a new factor to enhance matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) sensitivity. In MALDI-MS, several compounds are used as a standard matrix. Utilization of such compounds is based on an a posteriori approach, but there is no theoretical guidance for selecting a matrix. In an attempt to further understand performance in MALDI-MS, we utilized peptide detection for random screening of a chemical library (12,383 compounds) for compounds with matrix functions in MALDI-MS. A lot of thiophene compounds were found to be a matrix, in which 2-[5-(2,4-dichlorobenzoyl)-2-thienyl] acetic acid (DCBTA) provided an important clue to measure the electrical conductivity of the matrix crystal, because the structure of DCBTA is analogous to conductive polymers and organic solar cells. Most of the crystals of standard matrices, such as alpha-cyano-4-hydroxycinnamic acid (CHCA), 3,5-dimethoxy-4-hydroxycinnamic acid [sinapinic acid, (SA)], and DCBTA showed electrical conductivity, whereas the conductivity of crystal was not observed in 2,5-dihydroxybenzoic acid (2,5-DHB). On the other hand, super-DHB using 2-hydroxy-5-methoxybenzoic acid [5-methoxysalicylic acid, (MSA)] as an additive to 2,5-DHB, improved the electrical conductivity of the crystal, that followed the enhancement of peak intensity in MS spectrum. These observations might indicate that the electrical conductivity of matrix crystals is a key consideration in obtaining efficient MALDI performance.

    DOI: 10.1255/ejms.1215

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  • Protein-modified silver nanoplates for the complementary analytical method of localised surface plasmon resonance and matrix assisted laser desorption/ionisation mass spectrometry

    Masayuki Inuta, Ryuichi Arakawa, Hideya Kawasaki

    ANALYTICAL METHODS   5 ( 19 )   5031 - 5036   2013年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    A complementary analytical methodology combining localised surface plasmon resonance (LSPR) sensing and matrix assisted laser desorption/ionisation-mass spectrometry (MALDI-MS) has been developed by using triangular silver nanoplates (Ag NPLs). Ag NPLs with near-IR LSPR absorbance were prepared via a two-step photo-mediated growth process from Ag nanoparticles. These could be utilised as a common platform for LSPR/MALDI-MS, as they were suitable for LSPR sensing via the analysis of surface plasmon absorption bands and as the assisting material for LDI-MS. For practical use, the detection of analytes by LSPR sensing can be achieved by using specific biomolecular recognition techniques that involve the surface modification of metal NPs with large molecules such as proteins. We investigated the effect on LSPR sensitivity (i.e. refractive index unit, RIU) of modifying the Ag surface with molecules of different sizes, and found that the RIU values were proportional to the amplitude of the cube root of the molecular weight, M-w(1/3). We demonstrated the utility of this complementary LSPR and MALDI-MS analysis methodology by evaluating the binding of a soybean trypsin inhibitor to the Ag NPL substrate covalently modified with trypsin. This specific biomolecule recognition phenomenon was first detected using the LSPR technique, and then successfully identified by MALDI-MS.

    DOI: 10.1039/c3ay40708j

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  • Single nanosized FeO nanocrystals with photoluminescence properties

    Sugii, Yuta, Inada, Mitsuru, Yano, Hiroki, Obora, Yasushi, Iwasaki, Yasuhiko, Arakawa, Ryuichi, Kawasaki, Hideya

    Journal of Nanoparticle Research   15 ( 1 )   2013年

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1007/s11051-012-1379-2

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  • Desorption/Ionization Efficiency of Common Amino Acids in Surface-assisted Laser Desorption/ionization Mass Spectrometry (SALDI-MS) with Nanostructured Platinum, 査読

    S. Nitta, H. Kawasaki, T. Suganuma, Y. Shigeri, R. Arakawa

    J. Phys. Chem. C   117 , 238–245   2012年12月

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  • Correlations between Chemical Compositions and Retention Times of Methacrylate Random Copolymers Using LC-ESI 査読

    H. Hisatomi, Y. Nishimoto, H. Kawasaki, H, Momose, K. Ute, R. Arakawa

    Mass Spectrometry   1, 1-6   2012年11月

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  • Functionalized graphene-coated cobalt nanoparticles for highly efficient surface-assisted laser desorption/ionization mass spectrometry analysis

    Hideya Kawasaki, Keisuke Nakai, Ryuichi Arakawa, Evagelos K. Athanassiou, Robert N. Grass, Wendelin J. Stark

    Analytical Chemistry   84 ( 21 )   9268 - 9275   2012年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Graphene-coated cobalt nanoparticles surface-functionalized with benzylamine groups (CoC-NH2 nanomagnets) were shown to effectively enrich analytes for surface-assisted laser desorption/ionization mass spectrometry (affinity SALDI-MS) analysis. These CoC-NH2 nanomagnets are highly suited for use with affinity SALDI-MS because their mean diameter of 30 nm, high specific surface area of 15 m2 g-1, and high-strength saturation magnetization of 158 emu g-1 led to efficient extraction of analytes by magnetic separation, which in turn enabled excellent SALDI-MS performance. Surface modification of CoC nanomagnets with benzylamine groups increased the yield of peptide ions and decreased fragmentation of benzylpyridinium ions, so-called "thermometer ions" formed through soft ionization. The CoC-NH2 nanomagnets were used to extract perfluorooctanesulfonate from large volumes of aqueous solutions by magnetic separation, which was identified directly by SALDI-MS analysis with high sensitivity even at the sub-part-per-trillion level (∼0.1 ng/L). The applicability of CoC-NH2 nanomagnets in conjunction with SALDI-MS for the enrichment and detection of pentachlorophenol, bisphenol A, and polyfluorinated compounds (PFCs) with varying chain length, which are environmentally significant compounds, as well as small drugs, was also evaluated. © 2012 American Chemical Society.

    DOI: 10.1021/ac302004g

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  • Functionalized Graphene-Coated Cobalt Nanoparticles for Highly Efficient SALDI-MS analysis 査読

    H. Kawasaki, K. Nakai, R. Arakawa, E. K. Athanassiou, R. N. Grass, W. J. Stark

    Anal. Chem.   84, 9268-9275   2012年10月

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  • Laser Desorption/Ionization Mass Spectrometry Using Functionalized Metal Nanoparticles 査読

    H. Kawasaki

    J. Mass Spectrom. Soc. Jpn   1, 1-11   2012年9月

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  • New matrix of MALDI-TOF MS for the analysis of thiolate-protected gold clusters 査読

    H. Kouchi, H.Kawasaki, R. Arakawa

    Analytical Methods   4, 3600-3603   2012年9月

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  • Human Serum Albumin-modified Fe3O4 Magnetic Nanoparticles for Affinity-SALDI-MS of Small-Molecule Drugs in Biological Liquids

    Yuichi Iwaki, Hideya Kawasaki, Ryuichi Arakawa

    ANALYTICAL SCIENCES   28 ( 9 )   893 - 900   2012年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC ANALYTICAL CHEMISTRY  

    Here, we report on the use of human serum albumin (HSA)-modified Fe3O4 nanoparticles (NPs) (HSA-Fe3O4 NPs) for affinity-SALDI-MS of small drugs in human biological liquids. We demonstrated that HSA-Fe3O4 NPs effectively captured small drugs from human urine and serum via the interactions between HSA and these drugs. The drugs adsorbed on HSA could then be identified by directly introducing the HSA-Fe3O4 NPs into a mass spectrometer for SALDI-MS analysis. The ability of HSA to interact with multiple small drugs facilitated the simultaneous detection of a 4-drug-mixture in serum, viz., phenytoin, ibuprofen, camptothecin, and warfarin sodium, by affinity-SALDI-MS using HSA-Fe3O4 NPs. In contrast, matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) with an organic matrix could detect only warfarin sodium. We also demonstrated the capacity of affinity-SALDI-MS to quantify warfarin sodium in urine samples across a range of 50 - 1000 mu M (R-2 = 0.998) when using HSA-Fe3O4 NPs. The detection sensitivity was further improved to a range of 5 - 100 mu M (R-2 = 0.999) by using denatured HSA. The open structure of denatured HSA may enhance the effective extraction of small drugs from biological liquids, and increase the detection-sensitivity of affinity-SALDI-MS. Affinity-SALDI-MS using protein-modified Fe3O4 NPs can open up new approaches to the analytical detection of small drugs in biological liquids by SALDI-MS.

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  • Platinum vapor deposition surface-assisted laser desorption/ionization for imaging mass spectrometry of small molecules

    Hideya Kawasaki, Tomoyuki Ozawa, Hirotaka Hisatomi, Ryuichi Arakawa

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY   26 ( 16 )   1849 - 1858   2012年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-BLACKWELL  

    RATIONALE Matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) allows for the simultaneous detection and imaging of several molecules in a sample. However, when using an organic matrix in the MALDI-IMS of small molecules, inhomogeneous matrix crystallization may yield poorly reproducible peaks in the mass spectra. We describe a solvent-free approach that employs a homogeneously deposited metal nanoparticle layer (or film) for small-molecule detection. METHODS Platinum vapor deposition surface-assisted laser desorption/ionization imaging mass spectrometry (Pt vapor deposition SALDI-IMS) of small molecules was performed as a solvent-free and organic-matrix-free method. A commercially available magnetron sputtering device was used for Pt deposition. Vapor deposition of Pt produced a homogenous layer of nanoparticles over the surface of the target imaging sample. RESULTS The effectiveness of Pt vapor deposition SALDI-IMS was demonstrated for the direct detection of small analytes of inkjet ink on printed paper as well as for various other analytes (saccharides, pigments, and drugs) separated by thin-layer chromatography (TLC), without the need for extraction or concentration processes. The advantage of choosing Pt instead of Au in SALDI-IMS was also shown. CONCLUSIONS A solvent-free approach involving the direct deposition of Pt on samples (SALDI-IMS) is effective for the analysis of inkjet-printed papers and various analytes separated by TLC. This method would be useful in imaging analyses of various insulating materials such as polymers and biological materials. Copyright (C) 2012 John Wiley & Sons, Ltd.

    DOI: 10.1002/rcm.6301

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  • Evaluation of river pollution of neonicotinoids in Osaka City (Japan) by LC/MS with dopant-assisted photoionisation

    Atsushi Yamamoto, Tomoko Terao, Hirotaka Hisatomi, Hideya Kawasaki, Ryuichi Arakawa

    JOURNAL OF ENVIRONMENTAL MONITORING   14 ( 8 )   2189 - 2194   2012年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    An atmospheric pressure photoionisation (APPI) source for liquid chromatography/mass spectrometry (LC/MS) was applied to determine neonicotinoid pesticides in the aquatic environment. Dopant-assisted APPI was very effective in the ionisation of neonicotinoids. Neonicotinoids generated protonated molecules in APPI with high sensitivity, while adduct ions, such as sodiated molecules, were predominantly generated in conventional electrospray ionisation. The ionisation of neonicotinoids was confirmed by ultra-high-resolution MS. An analytical method coupled with solid phase extraction was developed for acetamiprid, clothianidin, dinotefuran, imidacloprid, nitenpyram, and thiamethoxam. Method detection limits were 0.47 to 2.1 ng L-1 for six neonicotinoids. Dinotefuran was the most frequent and highest among the neonicotinoids examined in the aquatic environment in Osaka, Japan. The maximum concentration of dinotefuran was 220 ng L-1. Given the toxicity of neonicotinoids for aquatic creatures, the concentrations observed here were substantially low. The change in concentrations was temporally coincident with the period of the neonicotinoid application. Although rapid photodegradation and some degradation products have been elucidated, the degradation products in the aquatic environment were not identified in the present study.

    DOI: 10.1039/c2em30296a

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  • 高度ナノ粒子の製法と応用 低温基材用ナノインクに向けたシングルナノサイズの銅ナノ粒子の製造法 招待

    川崎英也, 米澤徹, 荒川隆一

    ケミカルエンジニヤリング   57 ( 7 )   538-542 - 542   2012年7月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:化学工業社  

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  • Desorption/Ionization Efficiency of Peptides Containing Disulfide Bonds in Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry

    Yasushi Shigeri, Satoshi Inazumi, Yoshihisa Hagihara, Akikazu Yasuda, Hideya Kawasaki, Ryuichi Arakawa, Makoto Nakata

    ANALYTICAL SCIENCES   28 ( 3 )   295 - 299   2012年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC ANALYTICAL CHEMISTRY  

    In order to elucidate the role of desorption/ionization efficiency of peptides in MALDI-MS, we focused on peptides with disulfide bonds, which form a rigid tertiary structure. We synthesized seven sets of peptides with one disulfide bond (oxytocin, somatostatin, [Arg(8)]-vasopressin, [Arg(8)]-vasotocin, cortistatin, melanin-concentrating hormone, urotensin II-related peptide) and five sets of peptides with two disulfide bonds (tertiapin, alpha-conotoxin GI, alpha-conotoxin 1ml, a-conotoxin MI and alpha-conotoxin SI). Each peptide set consisted of three peptides: the oxidized form (S-S type), the reduced form (SH type), and an internal standard peptide in which all cysteine residues were substituted with alanine residues. In the case of urotensin II-related peptide, tertiapin, alpha-conotoxin ImI and alpha-conotoxin MI, the reduced form showed higher desorption/ionization efficiency than the oxidized form. In contrast, the other peptides revealed higher desorption/ionization efficiency in the oxidized form relative to the reduced form. These results imply that a rigid structure of peptides formed by disulfide bonds does not correlate with desorption/ionization efficiency in MALDI-MS.

    DOI: 10.2116/analsci.28.295

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  • N,N-Dimethylformamide-stabilized gold nanoclusters as a catalyst for the reduction of 4-nitrophenol

    H. Yamamoto, H. Yano, H. Kouchi, Y. Obora, R. Arakawa, H. Kawasaki

    NANOSCALE   4 ( 14 )   4148 - 4154   2012年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    In this study, we investigated the catalytic properties of N,N-dimethylformamide (DMF)-stabilized gold nanoclusters (AuNCs) in the reduction of 4-nitrophenol (PNP) to 4-aminophenol by NaBH4, a well known model reaction to be catalyzed by metal surfaces. The DMF-stabilized AuNCs were prepared in DMF by a surfactant-free method. The DMF-stabilized AuNCs showed high catalytic activity even when used in small quantities (similar to 10(-7) g). The pseudo-first-order rate constant (k(app)) and activation energy were estimated to be 3 x 10(-3) s(-1) and 31 kJ mol(-1), respectively, with 1.0 mu M of the gold catalyst at 298 K. The catalytic activity of the DMF-stabilized AuNCs was strongly influenced by the layer of adsorbed DMF on the Au NCs. This layer of adsorbed DMF prohibited the reactants from penetrating to the surface of the AuNCs via the diffusion at the beginning of the reaction, resulting in an induction time (t(0)) before PNP reduction began. Restructuring of the DMF layer (essentially a form of activation) was the key to achieving high catalytic activity. In addition, atomically monodisperse Au-25(SG)(18)NCs (SG: glutathione) showed higher catalytic activity in the PNP reduction (k(app) = 8 x 10(-3) s(-1)) even with a low catalyst concentration (1.0 mu M), and there was no induction time (t(0)) in spite of the strongly binding ligand glutathione. This suggested that the catalytically active surface sites of the Au-25(SG)(18)NCs were not sterically hindered, possibly because of the unique core-shell-like structure of the NCs. Retaining these open sites on AuNCs may be the key to making the NCs effective catalysts.

    DOI: 10.1039/c2nr30222e

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  • Surfactant-free single-nano-sized colloidal Cu nanoparticles for use as an active catalyst in Ullmann-coupling reaction

    Yuto Isomura, Takashi Narushima, Hideya Kawasaki, Tetsu Yonezawa, Yasushi Obora

    CHEMICAL COMMUNICATIONS   48 ( 31 )   3784 - 3786   2012年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    Surfactant-free, single-nano-sized copper nanoparticles (Cu NPs) (size: about 2 nm) were prepared by the DMF reduction method. The Cu NPs showed high catalytic activity (with a turnover number (TON) of up to 2.2 X 10(4)) in Ullmann-type cross-coupling of aryl halides with phenols under ligand-free conditions.

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  • ph-Dependent Synthesis of Pepsin-Mediated Gold Nanoclusters with Blue Green and Red Fluorescent Emission

    Hideya Kawasaki, Kenji Hamaguchi, Issey Osaka, Ryuichi Arakawa

    ADVANCED FUNCTIONAL MATERIALS   21 ( 18 )   3508 - 3515   2011年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    This report demonstrates the first pH-dependent synthesis of pepsin-mediated gold nanoclusters (AuNCs) with blue-, green-, and red-fluorescent emission from Au-5 (Au-8), Au-13, and Au-25, respectively. Pepsin is a gastric aspartic proteinase (molecular weight, 34 550 g/mol) that plays an integral role in the digestive process of vertebrates. It was found that the pH of the reaction solution was critical in determining the size of Au NCs (i.e., the number of gold atoms of AuNCs). Interestingly, enzyme function of pepsin contributes to the formation of these AuNCs. The photo-stability of the Au-25 (or Au-13) NCs is much higher than that of Au-5 NCs (i.e., Au-25 similar to Au-13 &gt; &gt; Au-5). The pepsin-mediated Au-25 NCs were also found to be useful as fluorescent sensors for the detection of Pb2+ ions by enhanced fluorescence and the detection of Hg2+ ions by fluorescence quenching. Although the detailed formation mechanisms of these AuNCs require further analysis, the synthetic route using proteinase demonstrated here is promising for preparing new types of fluorescent metal nanoclusters for application in catalysis, optics, biological labeling, and sensing.

    DOI: 10.1002/adfm.201100886

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  • Trypsin-Stabilized Fluorescent Gold Nanocluster for Sensitive and Selective Hg2+ Detection

    Hideya Kawasaki, Kouta Yoshimura, Kenji Hamaguchi, Ryuichi Arakawa

    ANALYTICAL SCIENCES   27 ( 6 )   591 - 596   2011年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC ANALYTICAL CHEMISTRY  

    We report on trypsin-stabilized fluorescent gold nanoclusters (Au NCs) for the sensitive and selective detection of Hg2+ ions. The Au NCs have an average size of 1 nm and show a red emission at 645 nm. The photostable properties of the trypsin-stabilized Au NCs were examined, and their photochemical stability was found to be similar to that of CdSe quantum dots. The fluorescence was particularly quenched by Hg2+, and therefore the Au NCs can be used as fluorescent sensors for sensitive and selective Hg2+ detection to a detection limit of 50 +/- 10 nM and the quantitative detection of Hg2+ in wide and low concentration range of 50 - 600 nM.

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  • Precise Synthesis of End-Functionalized Poly(vinyl chloride) with Butyllithium

    Kazuhiro Dohi, Yoshikatsu Tsuchiya, Kiyoshi Endo, Asuka Masumoto, Hideya Kawasaki, Ryuichi Arakawa

    MACROMOLECULES   44 ( 7 )   1808 - 1813   2011年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    The polymerization of vinyl chloride (VC) with n- or tert-butyllithium (n- or tert-BuLi) in the presence of allyl bromide (ABr) was evaluated for synthesizing the vinyl-terminated poly(vinyl chloride) macromonomer (PVCM). The structure of the product was based on the (1)H NMR and H-H COSY spectra. The functionality of the vinyl group was over 90%. To determine the detailed structure of PVCM, a MALDI-TOF-MS analysis of the PVCM derivative (PVC-DEA center dot HCl) obtained by the thiol-ene reaction of the macromonomer with 2-(diethylamino)ethanethiol hydrochloride was conducted. The MALDI mass spectrum of PVC-DEA center dot HCI in the absence of any ionizers exhibited only one series of ions repeating at an interval of 62 Da (which was the repeating VC unit), and the mass distribution agreed well with the calculated value of PVC-DEA center dot H(+) without any defect structures. The syndiotactic rich PVC was found to be synthesized by the polymerization of VC with BuLi in the presence of ABr. Especially, the obtained PVCM using tert-BuLi (ABr/BuLi = 10) was the most syndiotactic polymer (rr &gt; 80%).

    DOI: 10.1021/ma200042e

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  • 超音波分解を利用した合成高分子の質量分析(総合論文)

    R. Arakawa, H. Kawasaki

    分析化学   60 ( 3 )   199 - 214   2011年3月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

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  • Mass Spectrometry of Femto-Second Laser Photodegradation Products of Synthetic Polymers

    Daisuke Kurokawa, Hirotaka Hisatomi, Takehiro Watanabe, Tomoyuki Ozawa, Yukari Nishimoto, Hideya Kawasaki, Noriaki Ikeda, Ryuichi Arakawa

    BUNSEKI KAGAKU   60 ( 3 )   253 - 260   2011年3月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC ANALYTICAL CHEMISTRY  

    Femto-second laser photodegradations of polyethylene oxide (PEG), poly (ethylene oxide-b-propylene oxide) copolymer and polydimethylsiloxane (PDMS) were studied to investigate the degradation mechanism. MALDI-TOFMS and LGAPCI-MS were used for detail structural analysis of the degradation products. The results indicated that laser photodegradation proceeds within a few minutes in both aqueous and organic solutions. The degradation products of laser irradiation were identical to those of ultrasonic irradiation, but were not to those of thermal degradation in an aqueous solution using high-resolution mass spectrometry. Therefore, it is suggested that the mechanism of laser photodegradation of the polymers is due to the physical bond scissions through cavitation, just like ultrasonic degradation and the chemical reactions of the polymer chains with radicals formed from solvent or dissolved oxygen in laser-ablation.

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  • Polymer Analysis Utilizing Psuedo 2D Liquid Chromatogram Integrated with LC-ESI-MS Data Using Two Different Columns

    Hirotaka Hisatomi, Yukari Nishimoto, Tomoyuki Ozawa, Hideya Kawasaki, Koichi Ute, Ryuichi Arakawa

    BUNSEKI KAGAKU   60 ( 3 )   245 - 251   2011年3月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC ANALYTICAL CHEMISTRY  

    A simple and rapid method to provide a 2-dimensional liquid chromatogram (LCxLC) was developed for the characterization of synthetic polymers using liquid chromatography coupled with electrospray ionization mass spectrometry (LC-ESI-MS). Two sets of LC-MS chromatogram data using two different LC columns were prepared in property. The elution time of each chromatogram was plotted based on ions with the same m/z values, to give a scattering diagram of pseudo 2D-chromatogram. The application of this method was discussed to separate and identify a mixture of ten different polyethers.

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  • Laboratory scale production of C-13 labeled chitosan by fungi Absidia coerulea and Gongronella butleri grown in solid substrate and submerged fermentation

    Nitar Nwe, Tetsuya Furuike, Issey Osaka, Hiroki Fujimori, Hideya Kawasaki, Ryuichi Arakawa, Seiichi Tokura, Willem F. Stevens, Seiji Kurozumi, Yoshimori Takamori, Minoru Fukuda, Hiroshi Tamura

    CARBOHYDRATE POLYMERS   84 ( 2 )   743 - 750   2011年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCI LTD  

    Nowadays, chitin and chitosan are applied in many medical and pharmaceutical products. However little is known about the metabolism of chitin and chitosan in vivo. In the human body, lysozyme will degrade chitin and chitosan into chito-oligosaccharides. C-13 labeled chitosan is an essential prerequisite for the further study of the fate of chito-oligosaccharides in vivo. To fulfill this requirement, chitosans were extracted from mycelia of fungi. Absidia coerulea ATCC 14076 and Gongronella butleri USDB 0201 and ATCC 42618 grown in solid substrate fermentation (SSF) and submerged fermentation (SMF) to select the best fungus and fermentation method for the production of C-13 labeled chitosan. Based on the production yield of chitosan, the SSF method is the best method for the production of fungal chitosan when compared with SMF methods (i.e., fed-batch fermentation and batch fermentation). However synthesis of C-13 labeled chitosan in cell wall of G. butleri grown in SSF medium coated with 1-C-13-glucose was not observed. Alternatively, fungus A. coerulea was grown in SMF medium containing 2-C-13-glucose. The successful synthesis of C-13 labeled glucosamine from 2-C-13-glucose was observed in mycelia of A. coerulea grown in SMF medium containing 2-C-13-glucose in a yield of about 13 g/100 g mycelia. (C) 2010 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.carbpol.2010.06.023

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  • Use of thermally annealed multilayer gold nanoparticle films in combination analysis of localized surface plasmon resonance sensing and MALDI mass spectrometry

    Masayuki Inuta, Ryuichi Arakawa, Hideya Kawasaki

    ANALYST   136 ( 6 )   1167 - 1176   2011年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    A self-assembled film of gold nanoparticles (AuNPs) with a raspberry-like morphology was prepared on a glass plate by the layer-by-layer thermal annealing of multilayer films of AuNPs. It was possible to control the morphology of the obtained films of AuNPs by changing the annealing temperature, duration of annealing, and number of layers. On investigating the plasmonic properties of these films, we found that AuNP films with a raspberry-like morphology yielded the highest refractive index unit, which is a critical parameter in localized surface plasmon resonance (LSPR) sensing, as compared to other types of AuNP films. Self-assembled AuNP films with a raspberry-like morphology were subsequently functionalized with 11-mercaptoundecanoic acid (MUA) to enable the binding of lysozyme to the MUA-modified Au surface. The superior limit of detection for the LSPR sensing of lysozyme in a buffer solution was found to be in the picomolar range (similar to 10(-12) M). The high sensitivity observed in the region was attributed to the raspberry-like morphology, where the AuNPs were packed closely together, and the electromagnetic field confinement was most intense (i.e., at hot spots). The MUA-modified, self-assembled AuNP films with a raspberry-like morphology were finally used in the combination analysis of LSPR sensing and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) for the selective detection and identification of lysozyme in human serum.

    DOI: 10.1039/c0an00826e

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  • Photoluminescence from Excited Energy Bands in Au(25) Nanoclusters

    Sakanaga, Isamu, Inada, Mitsuru, Saitoh, Tadashi, Kawasaki, Hideya, Iwasaki, Yasuhiko, Yamada, Toshiki, Umezu, Ikurou, Sugimura, Akira

    Applied Physics Express   4 ( 9 )   2011年

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1143/APEX.4.095001

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  • Microwave-assisted polyol synthesis of copper nanocrystals without using additional protective agents

    Hideya Kawasaki, Yuka Kosaka, Yuki Myoujin, Takashi Narushima, Tetsu Yonezawa, Ryuichi Arakawa

    CHEMICAL COMMUNICATIONS   47 ( 27 )   7740 - 7742   2011年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    We report the synthesis of 2 nm copper nanocrystals (Cu NCs) via a microwave-assisted polyol method without using additional protective and reducing agents. The Cu NCs are oxidation resistant and exhibit photoluminescence and highly stable properties in a colloidal dispersion.

    DOI: 10.1039/c1cc12346g

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  • Surfactant-free synthesis of palladium nanoclusters for their use in catalytic cross-coupling reactions

    Megumi Hyotanishi, Yuto Isomura, Hiroko Yamamoto, Hideya Kawasaki, Yasushi Obora

    CHEMICAL COMMUNICATIONS   47 ( 20 )   5750 - 5752   2011年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    Surfactant-free Pd nanoclusters (Pd NCs) (size: 1-1.5 nm) showed high catalytic activity in the Suzuki-Miyaura cross-coupling and Mizoroki-Heck reactions. The Pd NCs had a high turnover number, up to 6.0 x 10(8), which can be recycled at least five times without loss of catalytic activity.

    DOI: 10.1039/c1cc11487e

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  • Roles of the C-terminal residues of calmodulin in structure and function

    Kitagawa Chihiro, Nakatomi Akiko, Hwang Dasol, Osaka Issey, Fujimori Hiroki, Kawasaki Hideya, Arakawa Ryuichi, Murakami Yota, Ohki Shinya

    BIOPHYSICS   7   35 - 49   2011年

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    記述言語:英語   出版者・発行元:The Biophysical Society of Japan  

    Electrospray ionization mass spectrometry (ESI-MS), circular dichroism (CD), nuclear magnetic resonance (NMR) spectroscopy, flow dialysis, and bioactivity measurements were employed to investigate the roles of the C-terminal residues of calmodulin (CaM). In the present study, we prepared a series of truncated mutants of chicken CaM that lack four (CCMΔ4) to eight (CCMΔ8) residues at the C-terminal end. It was found that CCMΔ4, lacking the last four residues (M145 to K148), binds four Ca<sup>2+</sup> ions. Further deletion gradually decreased the ability to bind the fourth Ca<sup>2+</sup> ion, and CCMΔ8 completely lost the ability. Interestingly, both lobes of Ca<sup>2+</sup>-sturated CCMΔ5 showed instability in the conformation, although limited part in the C-lobe of Ca<sup>2+</sup>-saturated CCMΔ4 was instable. Moreover, unlike CCMΔ4, structure of the C-lobe in CCMΔ5 bound to the target displayed dissimilarity to that of CaM, suggesting that deletion of M144 changes the binding manner. Deletion of the last five residues (M144 to K148) and further truncation of the C-terminal region decreased apparent capacity for target activation. Little contribution of the last four residues including M145 was observed for structural stability, Ca<sup>2+</sup>-binding, and target activation. Although both M144 and M145 have been recognized as key residues for the function, the present data suggest that M144 is a more important residue to attain Ca<sup>2+</sup> induced conformational change and to form a proper Ca<sup>2+</sup>-saturated conformation.<br>

    DOI: 10.2142/biophysics.7.35

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  • Development of precise tuning method of inter-dot spacing and resonant energy transfer between Au clusters 査読

    Inada, Mitsuru, Yoshihara, Yoshihiro, Kawasaki, Hideya, Iwasaki, Yasuhiko, Saitoh, Tadashi, Umezu, Ikurou, Sugimura, Akira, Cabrini, S, Mokari, T

    Nanophotonic Materials Viii   8094   2011年

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1117/12.893716

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  • 2種類のカラムを用いたLC-ESI-MSスペクトルを結合させた擬似2次元クロマトグラムによるポリマー分析

    H. Hisatomi, Y. Nishimoto, T. Ozawa, H. Kawasaki, K. Ute, R. Arakawa

    Bunseki Kagaku   60, 245-251   2011年

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  • Functionalized Nanoparticles and Nanostructured Surfaces for Surface-Assisted Laser Desorption/Ionization Mass Spectrometry

    Ryuichi Arakawa, Hideya Kawasaki

    ANALYTICAL SCIENCES   26 ( 12 )   1229 - 1240   2010年12月

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    記述言語:英語   出版者・発行元:JAPAN SOC ANALYTICAL CHEMISTRY  

    Surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF-MS) using nanoparticles (NPs) and nanostructured surfaces as the LDI-assisting nanomaterials is a soft ionization technique that features minimal fragmentation of analytes. As compared to traditional matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) using organic matrices, SALDI-MS affords several advantages, such as the ability to detect small molecules (&lt;500 Da), easy sample preparation, low-noise background, high salt tolerance, and fast data collection without the use of an organic matrix. The performance of SALDI has been further improved recently in terms of the detection sensitivity, detection mass range from the low- to the high-mass region, a soft LDI process, the detection of both polar and nonpolar compounds, the selective detection of analytes from a complex mixture using functionalized NPs, and various applications, including imaging mass spectrometry. This review summarizes recent developments pertaining to various NPs and nanostructured surfaces for SALDI-MS.

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  • Photochemical synthesis of glycine-stabilized gold nanoparticles and its heavy-metal-induced aggregation behavior

    Kenji Hamaguchi, Hideya Kawasaki, Ryuichi Arakawa

    COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS   367 ( 1-3 )   167 - 173   2010年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    In the present study, we carried out the photochemical synthesis of glycine-stabilized gold nanoparticles (Au NPs) at room temperature by using a photochemical initiator (Irgacure-2959). By adjusting the pH of the aqueous solution to 9 at the synthesis, we obtained a stable dispersion of anionic-glycine-stabilized Au NPs with sizes of about 5 nm; on the other hand, we obtained large and unstable neutral-glycine-capped Au NPs and cationic-glycine-capped Au NPs at pH 6 and 3, respectively. Anionic glycine has the highest affinity to Au NPs since the unprotonated amine and carboxylic groups of glycine interact with the gold surface. Heavy-metal-induced aggregation behavior of the glycine-stabilized Au NPs was also examined through the colorimetric detection of heavy metals (Ca2+, Cd2+, Co2+, Hg2+, Mg2+, Ni2+, Pb2+, and Zn2+). These sensitivities were nearly consistent with the complex formation constants (beta(1)) of glycine with these metal ions, but there was no difference between the detection limits of Hg2+ and Pb2+, irrespective of much higher beta(1) value of Hg2+ than that of Pb2+. It was suggested that this difference could be attributed to the difference in the binding behaviors of Hg2+ and Pb2+ with the glycine-capped Au NPs. (C) 2010 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.colsurfa.2010.07.006

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  • Carbon-Supported Growth of Cross-Linked Platinum Nanowires by Surfactant Templating and Their Elecrochemical Characterization

    Masafumi Uota, Yuichi Hayashi, Kosei Ohyama, Hirokatsu Takemoto, Ryosuke Iriki, Teppei Kishishita, Makoto Shimoda, Takumi Yoshimura, Hideya Kawasaki, Go Sakai, Tsuyoshi Kijima

    JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY   10 ( 9 )   5790 - 5795   2010年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER SCIENTIFIC PUBLISHERS  

    Platinum/carbon (Pt/C) composite materials were prepared by the hydrazine reduction of H(2)PtCl(6) confined to a mixed surfactant lytropic liquid crystal (LC)/C mixture with varying amounts of water. The reaction at relatively low water contents successfully yielded cross-linked Pt nanowires with wire-widths of 2-5 nm. The novel Pt nanostructure is believed to be from poorly hydrated hexagonal domains formed together with layered domains by the phase separation of the precursory LC mixture in the presence of carbon. Electrochemical measurements using cyclic volutammetry and membrane electrode assemblies revealed that the cross-linked nanowired Pt/C composite exhibits fairly high electrocatalytic activity for oxygen reduction reaction, as well as a high performance as the cathode material for polymer electrolyte fuel cells.

    DOI: 10.1166/jnn.2010.2439

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  • Semi-online nanoflow liquid chromatography/matrix-assisted laser desorption ionization mass spectrometry of synthetic polymers using an octadecylsilyl-modified monolithic silica capillary column

    Takehiro Watanabe, Keisuke Nakanishi, Tomoyuki Ozawa, Hideya Kawasaki, Koichi Ute, Ryuichi Arakawa

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY   24 ( 13 )   1835 - 1841   2010年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JOHN WILEY & SONS LTD  

    We have designed a semi-online liquid chromatography/matrix-assisted laser desorption/ionization mass spectrometry (LC/MALDI-MS) system to introduce eluent from a octadecylsilyl (ODS) group modified monolithic silica capillary chromatographic column directly onto a sample plate for MALDI-MS analysis. Our novel semi-online system is useful for rapidly and sensitively examining the performance of a monolithic capillary column. An additional advantage is the small elution volume of a monolithic capillary column, which allows delicate eluents, such as 1,1,1,3,3,3,-hexa-fluoroisopropyl alcohol (HFIP), to be used to achieve cost-effective analysis. Using the semi-online LC/MALDI-MS system, chromatographic separation of polymers by the monolithic column with different eluents was studied. Separation of poly(methyl methacrylate) and Nylon 6/6 showed that the column functioned via size-exclusion separation when tetrahydrofuran or HFIP eluent was used. On the other hand, the separation behavior of Nylon 11 indicated a reversed-phase mode owing to the interaction of the polymer with the modified ODS group in the column. Using tetrahydrofuran/methanol (1:1, v/v) as the eluent, the LC/MALDI-MS spectra of poly(lactic acid), which contains both linear and cyclic polymer structures, showed that the column could separate the hydrophobic cyclic polymer and elute it out relatively slowly. The monolithic column functions basically via size-exclusion separation; the reversed-phase separation by interaction with the ODS functions may have less influence on column separation. The semi-online monolithic capillary LC/MALDI-MS method we have developed should provide a means of effectively analyzing synthetic polymers. Copyright (C) 2010 John Wiley & Sons, Ltd.

    DOI: 10.1002/rcm.4584

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  • Determination of primary bond scissions by mass spectrometric analysis of ultrasonic degradation products of poly(ethylene oxide-block-propylene oxide) copolymers

    Takehiro Watanabe, Masanori Okabayashi, Daisuke Kurokawa, Yukari Nishimoto, Tomoyuki Ozawa, Hideya Kawasaki, Ryuichi Arakawa

    JOURNAL OF MASS SPECTROMETRY   45 ( 7 )   799 - 805   2010年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JOHN WILEY & SONS LTD  

    Ultrasonic degradation of poly(ethylene oxide-block-propylene oxide) copolymers consisting of a hydrophilic and a hydrophobic portion was studied with the aim to determine the location of bonds involved in the initial scission of the copolymers. LC-APCI-IT-MS and LC-APCI-orbitrap-MS were used for the detailed structural analysis of degradation products. The results indicated that initial bond scissions occurred principally at the boundary regions between backbones of polyethylene oxide (PEO) and polypropylene oxide (PPO) chains. Further structural analysis revealed the presence of oxygen adducts in the degradation products. Comparison with a thermal degradation carried out in helium atmosphere, one can conclude that the oxygen adducts are formed by radical reaction with water or dissolving oxygen molecules. The study demonstrated that chemical reactions as well as physical bond stress scissions are involved in the ultrasonic degradation of the copolymers. Copyright (C) 2010 John Wiley & Sons, Ltd.

    DOI: 10.1002/jms.1771

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  • Elimination Technique for Alkali Metal Ion Adducts from an Electrospray Ionization Process Using an On-line Ion Suppressor

    Kazuyoshi Nozaki, Akira Tarui, Issey Osaka, Hideya Kawasaki, Ryuichi Arakawa

    ANALYTICAL SCIENCES   26 ( 6 )   715 - 718   2010年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC ANALYTICAL CHEMISTRY  

    The effects of an on-line ion suppressor device on alkali metal ion adduct formations of the model compound tacrolimus were investigated. The base peak ion in the positive ion ESI-MS spectrum of tacrolimus was a sodium ion adduct, [M+Na](+). On the other hand, an ammonium ion adduct, [M+NH(4)](+), was the base peak ion in the full-scan mass spectrum of tacrolimus with a cation-exchange suppressor resin, and both [M+Na](+) and [M+K](+) were eliminated. These results indicate that the combination of an on-line ion suppressor with ESI-MS is a simple and effective technique that eliminates undesirable alkali metal ion adduct formations in the positive-ion mode.

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  • Detection of the Heterochirality of a 1:2 Metal/Ph-pybox Complex Ion by ESIMS

    Hirofumi Sato, Yoshitomo Suzuki, Yoshio Takai, Hideya Kawasaki, Ryuichi Arakawa, Motohiro Shizuma

    CHEMISTRY LETTERS   39 ( 6 )   564 - 566   2010年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHEMICAL SOC JAPAN  

    The heterochirality of a 1:2 metal/Ph-pybox complex ion was encyclopedically evaluated by ESIMS using pseudo-racemic (R,R)- and (S,S)-Ph-pybox pair, which were unlabeled/labeled by deuterium atoms, respectively. The heterochiral complex was predominantly formed in all investigated 1:2 metal/Ph-pybox complex ions.

    DOI: 10.1246/cl.2010.564

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  • Effectiveness of platinum particle deposition on silicon surfaces for surface-assisted laser desorption/ionization mass spectrometry of peptides

    Teruyuki Yao, Hideya Kawasaki, Takehiro Watanabe, Ryuichi Arakawa

    INTERNATIONAL JOURNAL OF MASS SPECTROMETRY   291 ( 3 )   145 - 151   2010年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    One of the problems associated with surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) using metal nanoparticles is that peptide analytes are characterized by alkali metal ion adducts even though in the presence of an excess proton source of trifluoroacetic acid in the mass spectra, and their alkali metal ion adducts are often observed in the low peak intensity. In this study, to improve the detection of the proton adduct form of the peptides, the effectiveness of platinum (Pt) particle deposition on a silicon plate for SALDI-MS was examined using the following different Pt-deposited silicon substrates: (1) Pt galvanic deposition (PGDS), (2) Pt particles deposited by suspension deposition on silicon, (3) evaporated Pt on oxidized silicon, and (4) evaporated Pt on bare silicon. Among these substrates, the PGDS plate exhibited the dominant proton adduct form of peptides in the SALDI mass spectra. In addition to platinum deposition, we attempted to employ palladium galvanic deposition as a SALDI-MS substrate, but it was found to lead mainly to the Na(+) and K(+) forms of the molecular ion. We propose that UV laser radiation-mediated surface-localized positive charges generated by effective charge separation (electron and hole) in the PGDS are important for the production of the proton adduct forms of peptides. Gly-Gly-Tyr-Arg, caffeine, raffinose, and beta-cyclodextrin were used as examples to demonstrate the feasibility of PGDS as a matrix-free method for LDI-MS. It was possible to detect these small molecules with SALDI-MS using PGDS; however, the detection sensitivity of these small molecules remains an unresolved issue. (C) 2010 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.ijms.2010.02.001

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  • Mass Spectrometric Approach Delineating Degradation Mechanism of Synthethic Polymers by Benzoylferrocene

    Shuji Kagawa, Hideya Kawasaki, Ryuichi Arakawa

    CHEMISTRY LETTERS   39 ( 1 )   66 - 67   2010年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHEMICAL SOC JAPAN  

    The degradation effects of benzoylferrocene (BF) on poly(ethylene glycol) (PEG) and poly(methyl methacrylate) (PMMA) were investigated using MALDI-MS. It is supposed that the release of free radicals in solution by BF plays a key role in the decomposition of PEG and PMMA. MALDI-MS combined with examination of the degradation by BF could be applied to the analysis of synthetic polymer structures containing the PEG and PMMA chain.

    DOI: 10.1246/cl.2010.66

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  • One-pot Preparation of Water-soluble Blue Luminescent Silica Flakes via Microwave Heating

    Iwasaki, Y, Shibata, Y, Watanabe, A, Inada, M, Kawasaki, H, Uchino, T

    Chemistry Letters   39 ( 4 )   2010年

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1246/cl.2010.370

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  • Stability of the DMF-Protected Au Nanoclusters: Photochemical, Dispersion, and Thermal Properties

    Kawasaki, H, Yamamoto, H, Fujimori, H, Arakawa, R, Iwasaki, Y, Inada, M

    Langmuir   26 ( 8 )   2010年

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/la9038842

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  • Efficient fabrication of substrates for surface-assisted laser desorption/ionization mass spectrometry using laser ablation in liquids 査読

    T. Tsuji, T. Mizuki, M.Yasutomo, M. Tsuji, H. Kawasaki, T. Yonezawa, F. Mafuné

    Applied Surface Science   257, 2046–2050   2010年

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  • Quantitative analysis of an antioxidant additive in insoluble plastics by surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) using TiO2 nanoparticle 査読

    I. Osaka, K. Okumura, N. Miyake, T. Watanabe, K. Nozaki, H. Kawasaki, R. Arakawa

    J. Mass Spectrom. Soc. Jpn.   58, 123-127   2010年

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  • Platinum Nanaflowers on Scratched Silicon by Galvanic Displacement for an Effective SALDI Substrate

    Hideya Kawasaki, Teruyuki Yao, Takashi Suganuma, Kouji Okumura, Yuichi Iwaki, Tetsu Yonezawa, Tatsuya Kikuchi, Ryuichi Arakawa

    CHEMISTRY-A EUROPEAN JOURNAL   16 ( 35 )   10832 - 10843   2010年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    We report a new and facile method for synthesizing 3D platinum nanoflowers (Pt Nfs) on a scratched silicon substrate by electroless galvanic displacement and discuss the applications of the Pt Nfs in surface-assisted laser desorption/ionization-mass spectrometry (SALDI-MS). Surface scratching of n-type silicon is essential to induce Pt Nf growth on a silicon substrate (to obtain a Pt Nf silicon hybrid plate) by the galvanic displacement reaction. The Pt Nf silicon hybrid plate showed excellent SALDI activity in terms of the efficient generation of protonated molecular ions in the absence of a citrate buffer. We propose that the acidity of the Si-OH moieties on silicon increases because of the electron-withdrawing nature of the Pt Nfs; hence, proton transfer from the Si OH groups to the analyte molecules is enhanced, and finally, thermal desorption of the analyte ions from the surface occurs. Signal enhancement was observed for protonated molecular ions produced from a titania nanotube array (TNA) substrate on which Pt nanoparticles had been photochemically deposited. Moreover, surface modification of the Pt Nf silicon hybrid plate by perfluorodecyltrichlorosilane (FDTS) (to obtain an FDTS-Pt Nf silicon hybrid plate) was found to facilitate soft SALDI of labile compounds. More interestingly, the FDTS-Pt Nf silicon hybrid plate acts 1) as a high-affinity substrate for phosphopeptides and 2) as a SALDI substrate. The feasibility of using the FDTS-Pt Nf silicon hybrid plate for SALDI-MS has been demonstrated by using a beta-casein digest and various analytes, including small molecules, peptides, phosphopeptides, phospholipids, carbohydrates, and synthetic polymers. The hybridization of Pt Nfs with a scratched silicon substrate has been found to be important for achieving excellent SALDI activity.

    DOI: 10.1002/chem.201001038

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  • Surfactant-free solution synthesis of fluorescent platinum subnanoclusters

    Kawasaki, H, Yamamoto, H, Fujimori, H, Arakawa, R, Inada, M, Iwasaki, Y

    Chemical Communications   46 ( 21 )   2010年

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1039/b925117k

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  • ガスクロマトグラフィー質量分析による壁画中の有機化合物の分析

    久富広隆, 浅井重博, 川崎英也, アフメド・シュエイブ, 吹田浩, 荒川隆一

    Institute for Conservation and Restoration of Cultural Properties Kansai University Japan   Vol 2, 103-109   2010年

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  • Influence of Crystalline Forms of Titania on Desorption/Ionization Efficiency in Titania-Based Surface-Assisted Laser Desorption/Ionization Mass Spectrometry 査読

    H. Kawasaki, K. Okumura, R. Arakawa

    J. Mass Spectrom. Soc. Jpn.   58, 221-228   2010年

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  • Aerosol Spectrometer for On-Line Measuring Diameters and Chemical Compositions of Volatile Organic Nanoparticles

    Y. Okada, T, Kida A. Kawasaki, H. Kawasaki, R. Arakawa

    Earozoru Kenkyu   25(4), 344–348   2010年

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  • Selective photocatalytic degradation of poly(ethylene glycol) additives using TiO2 surface-assisted laser desorption/ionization mass spectrometry

    Takehiro Watanabe, Koji Okumura, Kazuyoshi Nozaki, Hideya Kawasaki, Ryuichi Arakawa

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY   23 ( 23 )   3886 - 3890   2009年12月

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    記述言語:英語   出版者・発行元:WILEY-BLACKWELL  

    DOI: 10.1002/rcm.4305

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  • Simultaneous LC/MS Analysis of Hexachlorobenzene and Pentachlorophenol by Atmospheric Pressure Chemical Ionization (APCI) and Photoionization

    Issey Osaka, Arifumi Yoshimoto, Kazuyoshi Nozaki, Hiroshi Moriwaki, Hideya Kawasaki, Ryuichi Arakawa

    ANALYTICAL SCIENCES   25 ( 11 )   1373 - 1376   2009年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC ANALYTICAL CHEMISTRY  

    The simultaneous LC/MS analyses of hexachlorobenzene (HCB) and pentachlorophenol (PCP), two dioxin precursors were studied by both atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization mass spectrometry (APPI/MS). The optimum LC/MS conditions of the simultaneous analysis were determined for these two compounds with different polarity. Ionization by APPI was found to be more effective than by APCI, and is thus a better ionization method for analysis of the two compounds. Using LC/APPI/MS we can achieve the simultaneous analysis of HCB and PCP at ppb levels.

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  • Sulfonate group-modified FePtCu nanoparticles as a selective probe for LDI-MS analysis of oligopeptides from a peptide mixture and human serum proteins

    Hideya Kawasaki, Tarui Akira, Takehiro Watanabe, Kazuyoshi Nozaki, Tetsu Yonezawa, Ryuichi Arakawa

    ANALYTICAL AND BIOANALYTICAL CHEMISTRY   395 ( 5 )   1423 - 1431   2009年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER HEIDELBERG  

    Bare FePtCu nanoparticles (NPs) are first prepared for laser desorption/ionization mass spectroscopy (LDI-MS) analysis as affinity probes to selectively trap oppositely charged analytes from a sample solution. Our present results demonstrate bare FePtCu NPs to be a potentially useful matrix for surface-assisted laser desorption/ionization mass spectroscopy (SALDI-MS), for the analysis of small proteins and peptides. The upper detectable mass range of peptides was approximately 5 kDa, and the detection limit for peptides approximately 5 fmol. Sulfonate group-modified FePtCu nanoparticles (FePtCu-SO(3)(-) NPs), with ionization being independent of the solution pH, can interact with a positively charged analyte, and the analyte-bound NPs can be separated from the reaction supernatant by centrifugation or an external magnetic field. An oligopeptide, Gly-Gly-Tyr-Arg (GGYR) from an oligopeptide mixture containing Asp-Asp-Asp-Asp (DDDD), Gly-Gly-Gly-Gly (GGGG) and GGYR, was detected using SALDI-MS with FePtCu-SO(3)(-) NPs employing electrostatic interaction. Furthermore, FePtCuSO(3)(-) NPs can detect lysozyme (Lyz) in human serum through the electrostatic attraction between positively charged Lyz and FePtCu-SO(3)(-) NPs at pH 8, while detection of negatively charged albumin in human serum is not possible.

    DOI: 10.1007/s00216-009-3122-0

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  • Functionalized pyrolytic highly oriented graphite polymer film for surface-assisted laser desorption/ionization mass spectrometry in environmental analysis

    Hideya Kawasaki, Naoyuki Takahashi, Hiroki Fujimori, Kouji Okumura, Takehiro Watanabe, Chisato Matsumura, Syusuke Takemine, Takeshi Nakano, Ryuichi Arakawa

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY   23 ( 20 )   3323 - 3332   2009年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JOHN WILEY & SONS LTD  

    The pyrolytic highly oriented graphite polymer film (PGS) was first employed to analyze low-mass analytes in environmental analysis by surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). PGS is a synthetic uniform and highly oriented graphite polymer film with high thermal anisotropic conductivity. We have found that negative ion mode SALDI-MS using oxidized PGS (PGS-SALDI-MS) can be used to detect [M-H](-) ions from perfluorooctanoic acid (PFOA) and other perfluoroalkylcarboxylic acids when the PGS surface is modified with the cationic polymer polyethyleneimine (PEI). The signal intensity of PFOA when employing the PEI modification showed a ten-fold increase over that obtained from desorption/ionization on porous silicon (DIOS). PFOA was quantified using PGS-SALDI-MS and the calibration curve showed a wide linear dynamic range of response (20-1000 ppb). The combination of atmospheric pressure ionization and PGS (AP-PGS-SALDI) showed greater signal intensity than vacuum PGS-SALDI for deprotonated PFOA. Several other environmentally important chemicals, including perfluoroalkylsulfonic acid, pentachlorophenol, bisphenol A, 4-hydroxy-2-chlorobiphenyl, and benzo[a]pyrene, were also successfully used to evaluate PGS-SALDI-MS. In addition, we found that nonafluoro-l-butanesulfonic acid was able to produce protonated peptides in positive ion PGS-SALDI-MS, but that perfluoropentanoic acid and trifluoroacetic acid were not. It is suggested that perfluoroalkylsulfonic acids are better protonating agents than perfluoroalkylcarboxylic acids in SALDI-MS. Copyright (C) 2009 John Wiley & Sons, Ltd.

    DOI: 10.1002/rcm.4254

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  • Effect of urea surface modification and photocatalytic cleaning on surface-assisted laser desorption ionization mass spectrometry with amorphous TiO2 nanoparticles

    Takehiro Watanabe, Koji Okumura, Hideya Kawasaki, Ryuichi Arakawa

    JOURNAL OF MASS SPECTROMETRY   44 ( 10 )   1443 - 1451   2009年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-BLACKWELL  

    We have investigated the effect of urea surface modification and the photocatalytic cleaning on surface-assisted laser desorption ionization mass spectrometry (SALDI-MS) with amorphous TiO2 nanoparticles for the reduction of the background noise and the improvement of the sensitivity. In the use of nanoparticles of high surface area, chemical background signals arising from ambient environments and organic contaminants can frequently be serious problems below 500 Da, possibly reducing the advantages of the matrix-free approach. In this study, removal of contaminants and enhanced SALDI efficiency were easily achieved with UV irradiation via the photocatalyst effect of TiO2 before SALDI-MS measurements. The surface cleaning achieved by the UV photocatalytic procedure reduced the background noise and increased the peak intensities of peptides. in addition, we found that urea surface modification of TiO2 nanoparticles increased the performance of the TiO2-SALDI-MS. (1) The urea-surface modification of TiO2 made it possible to produce proton-adduct forms without citrate buffer, resulting in low background noises below 500 Da, in contrast to the essential use of a citrate buffer in the bare TiO2-SALDI-MS. (2) The detection sensitivity of angiotensin I increased to 0.3 fmol with the urea-surface modification, as compared to the use of bare TiO2 nanoparticles (6 fmol). The urea-TiO2 could ionize proteins of more than 20 000 Da such as trypsinogen (600 fmol). (3) The urea modification of TiO2 had the advantage of selective detection of phosphopeptides without sample clean up, or prefractionation in tryptic digest products of bovine hemoglobin. Copyright (C) 2009 John Wiley & Sons, Ltd.

    DOI: 10.1002/jms.1628

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  • Desorption/ionization on porous silicon mass spectrometry (DIOS-MS) of perfluorooctane sulfonate (PFOS)

    Hideya Kawasaki, Yukiyasu Shimomae, Takehiro Watanabe, Ryuichi Arakawa

    COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS   347 ( 1-3 )   220 - 224   2009年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Desorption/ionization on porous silicon mass spectrometry (DIOS-MS) was introduced as a matrix-free LDI-TOF-MS, which succeeded at almost eliminating the background ion interference and offered a new technology for high-speed analysis of low mass compounds. In this study, we first demonstrated that the DIOS-MS is very useful for environmental analysis of perfluorooctane sulfonate (PFOS). In particular, DIOS can detect PFOS with the high sensitivity and the detection limit was 1 ppt without the extraction operation. At the very low concentration of 1 ppt, the PFOS was not detectable with the use of the traditional MS methods such as MALDI-MS and ESI-MS. The quantitative analysis of PFOS in the tap water was also performed from the calibration curve in the low concentration range from 2.5 to 10 ppb. In contrast, it was found that DIOS-MS has a low sensitivity for PFOA. This suggests that the DIOS plate has a high sensitivity for perfluorochemicals of sulfonic acid than that of carboxylic acid as the ionized group. (C) 2009 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.colsurfa.2009.04.035

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  • Electrospray ionization mass spectrometric observation of ligand exchange of zinc pyrithione with amino acids

    Hiroshi Moriwaki, Masanori Okabayashi, Takehiro Watanabe, Hideya Kawasaki, Ryuichi Arakawa

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY   23 ( 14 )   2161 - 2166   2009年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JOHN WILEY & SONS LTD  

    Zinc pyrithione (ZnPT) is widely used as an antidandruff or antifouling reagent. However, this compound is considered toxic, such as the teratogenic effect, to aquatic lives, and it is important to clarify the mechanism of its toxicity. In this study, the interactions between ZnPT and amino acids were observed using electrospray ionization mass spectrometry (ESI-MS) in order to obtain information on the activity of ZnPT within the living body. The ZnPT complex ([ZnPT-ligand+Amino acid](+)), in which the ligand of ZnPT was exchanged by the amino acid, was detected in ZnPT solutions mixed with one of 20 amino acids by ESI-MS. Histidine and cysteine, in particular, showed a high reactivity with ZnPT, while serine and glycine showed a low reactivity. The complexes of ZnPT and a peptide were also observed by the ESI-MS measurement of the solution containing ZnPT with the peptide. These results would be useful to understand the mechanism of ZnPT toxicities to living creatures. Copyright (C) 2009 John Wiley & Sons, Ltd.

    DOI: 10.1002/rcm.4128

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  • Ionization efficiency of alpha-helical peptides in laser desorption/ionization mass spectrometry

    Yasushi Shigeri, Satoshi Fujii, Ryo Obana, Yoshihisa Hagihara, Mamiko Jitosho, Hideya Kawasaki, Ryuichi Arakawa

    JOURNAL OF MASS SPECTROMETRY   44 ( 7 )   1119 - 1123   2009年7月

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    記述言語:英語   出版者・発行元:JOHN WILEY & SONS LTD  

    One of the major problems in proteome analysis is that &lt;50-80% of the peptide fragments generated by the digestion of proteins can be detected by mass spectrometry (MS).([1]) In consequence, inaccuracy of protein identification and lower sensitivity to the detection of post-translational modification occurs in proteome analysis. In addition to suppression effects in peptide mixtures, ([2]) several intrinsic properties of peptides, such as size,([3]) hydrophobicity,([3]) the presence of charged side chain, ([1,4]) aromatic amino acids([1,5]) and secondary structure,([6]) have been reported to influence the ionization efficiency of peptides in laser desorption/ionization MS.

    DOI: 10.1002/jms.1574

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  • Analysis of Chlorothalonil by Liquid Chromatography/Mass Spectrometry Using Negative-ion Atmospheric Pressure Photoionization

    Atsushi Yamamoto, Lori Miyamato, Mikiya Kitagawa, Hiroshi Moriwaki, Hidekazu Miyakoda, Hideya Kawasaki, Ryuichi Arakawa

    ANALYTICAL SCIENCES   25 ( 5 )   693 - 697   2009年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC ANALYTICAL CHEMISTRY  

    A highly sensitive and simple method for the analysis of chlorothalonil was presented using a liquid chromatograph/mass spectrometer equipped with an atmospheric pressure photoionization (APPI) Source. Chlorothalonil is one of the most extensively used fungicides. The major degraded product of chlorothalonil, 4-hydroxy-2,5,6-trichloroisonaphthonitrile (4OH-TPN), was also quantified with sensitivity similar to that of chlorothalonil. The method was applied to the determination of chlorothalonil in aqueous environment and food samples. The method detection limits (MDLs) of chlorothalonil for aqueous samples and cucumber were determined to be 0.18 and 3.2 ng g(-1). respectively. At several estuarial locations, chlorothalonil was detected with a maximum of 1.1 ng L(-1). Oil the other hand, 4OH-TPN was detected not from estuaries but from rivers with a maximum of 14 ng L(-1).

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  • Detailed Investigation on the Possibility of Nanoparticles of Various Metal Elements for Surface-Assisted Laser Desorption/Ionization Mass Spectrometry

    Tetsu Yonezawa, Hideya Kawasaki, Akira Tarui, Takehiro Watanabe, Ryuichi Arakawa, Toshihiro Shimada, Fumitaka Mafune

    ANALYTICAL SCIENCES   25 ( 3 )   339 - 346   2009年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC ANALYTICAL CHEMISTRY  

    In this paper, we describe systematic detailed considerations of the feasibility of using various metal nanoparticles for organic-matrix-free surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). In order to avoid the influence of organic molecules on the nanoparticles, stabilizer-free bare nanoparticles of Ag, Au, Cu and Pt were prepared by laser ablation. Although all metal nanoparticles absorbed N-2 laser light (337 nm) energy, the performance of desorption/ionization of a representative peptide, angiotensin 1, strongly depended on the metal element. Citrate buffer was used as a proton source; it reduced the amount of alkali cation adducts present. Then, protonated molecules of analytes predominated in the mass spectra when Au and Pt nanoparticles were used. Pt nanoparticles showed the highest performance in SALDI-MS, owing to their smaller heat conductivity and higher melting temperature. The selective desorption of a cationic surfactant with longer alkyl chains and a peptide with methionine was also observed.

    DOI: 10.2116/analsci.25.339

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  • Analysis of Contaminants Eluted from Vials, Septa and Syringe Filters in High-Performance Liquid Chromatography/Mass Spectrometry

    Arifumi Yoshimoto, Yukari Nishimoto, Chizuko Ishihara, Hideya Kawasaki, Ryuichi Arakawa

    BUNSEKI KAGAKU   58 ( 2 )   95 - 100   2009年2月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC ANALYTICAL CHEMISTRY  

    Various contaminants alight be frequently detected in high-performance liquid chromatography/mass spectrometry (LC/MS) experiments. This makes highly accurate qualitative and quantitative analyses of LC/MS difficult. It is necessary to know the identification and origin of the contaminants to prevent them from being mixed. In the present work, we paid attention to any contaminants eluted from vials, septa and syringe filters used for an automatic sampling device and filtration preparation in LC/MS experiments. Some contaminants were identified by LC/MS and MS/MS analysis. In addition, we could specify the contaminant source.

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  • Synthesis of Nanohole-Structured Single-Crystalline Platinum Nanosheets Using Surfactant-Liquid-Crystals and their Electrochemical Characterization

    Tsuyoshi Kijima, Yu Nagatomo, Hirokatsu Takemoto, Masafumi Uota, Daisuke Fujikawa, Yuzo Sekiya, Teppei Kishishita, Makoto Shimoda, Takumi Yoshimura, Hideyo Kawasaki, Go Sakai

    ADVANCED FUNCTIONAL MATERIALS   19 ( 4 )   545 - 553   2009年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    Nanohole-structured single-crystalline Pt nanosheets have been synthesized by the borohydride reduction of Na(2)PtCl(6) confined to the lyotropic liquid crystals (LLCs) of polyoxyethylene (20) sorbitan monooleate (Tween 80) with or without nonaethylene-glycol (C(12)EO(9)). The Pt nanosheets of around 410 nm in central thickness and up to 500 nm or above in diameter have a number of hexagonal-shaped nanoholes similar to 1.8 nm wide. High-resolution electron microscope images of the nanosheets showed atomic fringes with a spacing of 0.22 nm indicating that the nanosheets are crystallographically continuous through the nanoholed and non-holed areas. The inner-angle distributions for the hexagonal nanoholes indicate that the six sides of the nanoholes are walled with each two Pt (111), Pt (1(1) over bar 1) and Pt (010) planes. The formation mechanism of nanoholed Pt nanosheets is discussed on the basis of structural and compositional data for the resulting solids and their precursory LLCs, with the aid of similar nanohole growth observed for a Tween 80 free but oleic acid-incorporated system. It is also demonstrated that the nanoholed Pt nanostructures loaded on carbon exhibit fairly high electrocatalytic activity for oxygen reduction reaction and a high performance as a cathode material for polymer-electrolyte fuel cells, along with their extremely high thermostability revealed through the effect of electron-irradiation.

    DOI: 10.1002/adfm.200800966

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  • Gold-Nanoparticle-Supported Silicon Plate with Polymer Micelles for Surface-Assisted Laser Desorption/Ionization Mass Spectrometry of Peptides

    Akira Tarui, Hideya Kawasaki, Takuma Taiko, Takehiro Watanabe, Tetsu Yonezawa, Ryuichi Arakawa

    JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY   9 ( 1 )   159 - 164   2009年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER SCIENTIFIC PUBLISHERS  

    We developed surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) using nanocomposite films of cationic diblock copolymer micelles [poly(styrene-b-N-methyl-4-vinyl pyridinium iodide)] and ammonium citrated Au nanoparticles (AuNPs) on silicon. The nanocomposite film on silicon was suitable for use as a material for matrix-free LDI-MS of peptides due to its low matrix background from Au clusters and high ionization efficiency; this plate successfully ionized angiotensin I, and also insulin in the proton adduct forms, in contrast to methods using only AuNPs and those using nanocomposite films of cationic polymer in conjunction with Au NPs. The high ionization efficiency is discussed from the viewpoint of nanoparticle distribution controlled by polymers on the plate (aggregates vs. nonaggregates).

    DOI: 10.1166/jnn.2009.J046

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  • Reassessment of Free-Radical Polymerization Mechanism of Allyl Acetate Based on End-Group Determination of Resulting Oligomers by MALDI-TOF-MS Spectrometry

    Akira Matsumoto, Takeo Kumagai, Hiroyuki Aota, Hideya Kawasaki, Ryuichi Arakawa

    POLYMER JOURNAL   41 ( 1 )   26 - 33   2009年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SOC POLYMER SCIENCE JAPAN  

    Allyl monomers polymerize only with difficulty and yield polymers of medium-molecular-weight or oligomers. This is attributable to "degradative monomer chain transfer." However, the well-known allyl polymerization mechanism is based on only the kinetic data but any structural identification is not given. Allyl acetate (AAc), a most typical allyl monomer, was polymerized radically and the resultant oligomeric poly(AAc)s were characterized using MALDI-TOF-MS spectrometry in order to reassess the AAc polymerization mechanism proposed by Litt and Eirich. The induced decomposition of benzoyl peroxide by both growing polymer radical and monomeric allyl radical was presumed but it was never of importance. Then, the fate of resonance-stabilized monomeric allyl radical generated via monomer chain transfer of growing polymer radical was pursued in terms of the competition between the initiation of a new polymer chain and the chain stopping reaction of a growing polymer radical providing monomeric allyl groups as the initial and terminal end-groups, respectively. The monomer chain transfer constant was estimated to be 3.73 x 10(-2) from the P(n) value of poly(AAc) obtained at a low initiator concentration where the coupling termination of growing polymer radical with monomeric allyl radical was negligible.

    DOI: 10.1295/polymj.PJ2008174

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  • 脱離エレクトロスプレーイオン化質量分析用イオン源の試作と迅速分析への応用 査読

    川崎英也, 芳本有史, 元木翔一, 森脇悠介, 荒川隆一

    Journal of the Mass Spectrometry Society of Japan   57,109-115   2009年

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  • Characterization of Silver Ion Complexes adsorbed on Gold Nanorods: Surface Analysis by Using Surface-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectroscopy (SALDI-MS) 査読

    H. Kawasaki, Y. Niidome, Y. Nakamura, K. Honda, Y.Akiyama, K. Nishioka, N. Nakashima

    Chem. Comm.   1754-1796   2009年

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  • P05 ソノルミネッセンスと合成高分子の超音波分解効率の相関性

    當田 紀賢, 黒川 大肋, 渡辺 健宏, 山本 健, 川崎 英也, 荒川 隆一

    ソノケミストリー討論会講演論文集   18   37 - 38   2009年

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    記述言語:日本語   出版者・発行元:日本ソノケミストリー学会  

    The correlation between sonoluminescence and ultrasonic degradation (UD) efficiency of polyethylene glycol (PEG) was studied using 100, 400, and 1000 kHz ultrasonic transducers. The intensity of luminol luminescence was obtained from visualization of cavitation and sonication of PEG was measured using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The results showed that both the luminescence due to reactive radicals and the sonication of polymers were accelerated with increasing in applied voltage and the 400 kHz transducer was the highest efficient for the sonication of PEG. As a result, the luminescence was found to give an indication of optimization for polymer degradation.

    DOI: 10.20577/pamjss.18.0_37

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  • P04 高分解能質量分析法を用いた合成高分子の超音波分解生成物の分析

    渡辺 健宏, 黒川 大肋, 小澤 智行, 川崎 英也, 荒川 隆一

    ソノケミストリー討論会講演論文集   18   35 - 36   2009年

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    記述言語:日本語   出版者・発行元:日本ソノケミストリー学会  

    The ultrasonic degradation products of poly(ethylene oxide)-poly(propylene oxide) diblock copolymers were characterized by MALDI-TOF-MS and high resolution mass spectrometry. Several ions in the products could not be assigned by MALDI-TOF-MS because of its low mass resolution. However, using high resolution mass spectrometry it was determined whether the end-group of these ions is oxo or ethoxy structure. The mass spectra obtained with high mass resolution are useful information for detailed analyses of repeat unit and end-group of the ultrasonic degradation products.

    DOI: 10.20577/pamjss.18.0_35

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  • Application of on-line electrochemistry/electrospray/tandem mass spectrometry to a quantification method for the antipsychotic drug zotepine in human serum

    K. Nozaki, I. Osaka, H. Kawasaki, R. Arakawa

    Ana. Sci.   25, 1197-1201   2009年

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  • Halohydrination of epoxy resins using sodium halides as cationizing agents in MALDI-MS and DIOS-MS

    Takehiro Watanabe, Hideya Kawasaki, Takashi Kimoto, Ryuichi Arakawa

    JOURNAL OF MASS SPECTROMETRY   43 ( 12 )   1664 - 1672   2008年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JOHN WILEY & SONS LTD  

    Halohydrination of epoxy resins using sodium halides as cationizing agents in matrix-assisted laser desorption/ionization (MALDI) and desorption ionization on porous silicon mass spectrometry (DIOS-MS) were investigated. Different mass spectra were observed when NaClO(4) and NaI were used as the cationizing agents at the highest concentration of 10.0 mM, which is much higher than that normally used in MALDI-MS. MALDI mass spectra of epoxy resins using NaI revealed iodohydrination to occur as epoxy functions of the polymers. The halohydrination also occurred using NaBr, but not NaCl, due to the differences in their nucleophilicities. On the basis of the results of experiments using deuterated CD(3)OD as the solvent, the hydrogen atom source was probably ambient water or residual solvent, rather than being derived from matrices. Halohydrination also occurred with DIOS-MS in which no organic matrix was used; in addition, reduction of epoxy functions was observed with DIOS. NaI is a useful cationizing agent for changing the chemical form of epoxy resins due to iodohydrination and, thus, for identifying the presence of epoxy functions. Copyright (C) 2008 John Wiley & Sons, Ltd.

    DOI: 10.1002/jms.1454

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  • Layer-by-layer self-assembled mutilayer films of gold nanoparticles for surface-assisted laser desorption/ionization mass spectrometry

    Hideya Kawasaki, Tsuyoshi Sugitani, Takehiro Watanabe, Tetsu Yonezawa, Hiroshi Moriwaki, Ryuichi Arakawa

    ANALYTICAL CHEMISTRY   80 ( 19 )   7524 - 7533   2008年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Layer-by-layer (LBL) self-assembled multilayer films of gold nanoparticles (AuNPs) on a silicon wafer were demonstrated to be promising substrates for surface-assisted laser desorption/ionization (SALDI) mass spectrometry (MS) of peptides and environmental pollutants for the first time. LBL multilayer films, (AuNPs/PAHC)(n), consisting of alternating layers of ammonium citrate capped AuNPs and poly(allylamine hydrochloride) (PAHC) were prepared on a silicon surface. Silicon plates with aggregated AuNPs were more suitable than those with dispersed AuNPs for the SALDI-MS of peptides. The number of particle layers had a significant effect on the laser desorption/ionization of angiotensin I; the peak intensity of the peptide (molecular ion amount) increased with an increase in the number of layers of AuNPs. As a result, the (AuNPs/PAHC)(5) multilayer films increased the sensitivity of the angiotensin I to subfemtomoles and raised the useful analyte mass range, thus making it possible to detect small proteins (a 12 kDa cytochrome c). The signal enhancement when using (AuNPs/PAHC)(5) may be due to (i) the high absorption of the UV laser fight at 337 nm by the AuNP layers, (ii) the low thermal conductivity due to the AuNPs being covered with a thin monolayer of PAHC, and (iii) the increase in the surface roughness (similar to 100 nm) with the number of AuNP layers. Thus, laser-induced rapid high heating of AuNPs for effective desorption/ionization of peptides is possible. In addition, it was found that (AuNPs/PAHC)(5) could be used to extract environmental pollutants (pyrene and dimethyldistearylammonium chloride) from very dilute aqueous solutions with concentrations less than 10(-10) mg/mL, and the analytes trapped in the LBL film could be identified by introducing the film directly into the SALDI mass spectrometer without needing to elute the analytes out of the film.

    DOI: 10.1021/ac800789t

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  • Specific Polymerization Mechanism Involving beta-Scission of Mid-Chain Radical Yielding Oligomers in the Free-Radical Polymerization of Vinyl Ethers

    Takeo Kumagai, Chihiro Kagawa, Hiroyuki Aota, Yoshiki Takeda, Hideya Kawasaki, Ryuichi Arakawa, Akira Matsumoto

    MACROMOLECULES   41 ( 20 )   7347 - 7351   2008年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Butyl vinyl ether (BVE) was polymerized radically, and the resultant oligomeric poly(BVE)s were characterized mainly using MALDI-TOF-MS spectrometry. For a further structural identification, the poly(BVE) obtained in bulk was subsequently subjected to H-1 NMR measurement. Notably, an intensive peak assignable to -CH2C(=O)CH2- protons was observed unexpectedly although a peak assignable to -CHO proton as the terminal end-group generated via beta-scission of growing polymer radical as a presumed chain-end forming reaction appeared only weakly. Thus, a plausible chain-end forming reaction would be the intramolecular (backbiting) hydrogen abstraction to form mid-chain radical which subsequently undergoes beta-scission resulting in oligomeric poly(BVE) radical was checked by using toluene as a solvent having labile hydrogen. The dependence of the degree of polymerization on initiator concentration was examined because the occurence of primary radical termination was remarkable, probably leading to reduce chain length. Finally, the reinitiation reaction by butyl group generated via beta-scission of mid-chain radical was pursued.

    DOI: 10.1021/ma800949q

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  • Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) of low molecular weight organic compounds and synthetic polymers using zinc oxide (ZnO) nanoparticles

    Takehiro Watanabe, Hideya Kawasaki, Tetsu Yonezawa, Ryuichi Arakawa

    JOURNAL OF MASS SPECTROMETRY   43 ( 8 )   1063 - 1071   2008年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JOHN WILEY & SONS LTD  

    We have developed surface-assisted laser desorption/ionization mass spectrometry using zinc oxide (ZnO) nanoparticles with anisotropic shapes (ZnO-SALDI-MS). The mass spectra showed low background noises in the low m/z, i.e. less than 500 u region. Thus, we succeeded in SALDI ionization on low molecular weight organic compounds, such as verapamil hydrochloride, testosterone, and polypropylene glycol (PPG) (average molecular weight 400) without using a liquid matrix or buffers such as citric acids. In addition, we found that ZnO-SALDI has advantages in post-source decay (PSD) analysis and produced a simple mass spectrum for phospholipids. The ZnO-SALDI spectra for synthetic polymers of polyethylene glycol (PEG), polystyrene (PS) and polymethylmethacrylate (PMMA) showed the sensitivity and molecular weight distribution to be comparable to matrix-assisted laser desorption/ionization (MALDI) spectra with a 2,5-dihydroxybenzoic acid (DHB) matrix. ZnO-SALDI shows good performance for synthetic polymers as well as low molecular weight organic compounds. Copyright (C) 2008 John Wiley & Sons, Ltd.

    DOI: 10.1062/jms.1385

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  • Quantitative determination of cyclic polylactic acid oligomers in serum by direct injection liquid chromatography tandem mass spectrometry

    Issey Osaka, Arihumi Yoshimoto, Mikio Watanabe, Masashi Takama, Masahiro Murakami, Hideya Kawasaki, Ryuichi Arakawa

    JOURNAL OF CHROMATOGRAPHY B-ANALYTICAL TECHNOLOGIES IN THE BIOMEDICAL AND LIFE SCIENCES   870 ( 2 )   247 - 250   2008年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Polylactic acid (PLA) is a biodegradable polymer, currently used in pharmaceutical and surgical devices. There is a concern that cyclic polylactic acid (CPLA), which is a by-product of PLA synthesis, may be introduced into the human body as an undesirable contaminant. We Carried out a quantitation investigation of the CPLA heptamer (CPLA-7) by liquid chromatography mass spectrometry (LC-MS). We found that CPLA-7 binds strongly with serum proteins and that only 62% of CPLA-7 was recovered after routine deproteination; therefore, we directly injected serum into the LC-MS/MS system after passage through a bovine serum albumin (BSA)-coated chromatographic column and found the recovery of CPLA-7 was improved to 84%, and that the detection (S/N = 3) and quantitation limit (S/N = 10 and below 15% relative standard deviation) were 1.5 and 2.5 ng/mL, respectively. We conclude that direct injection LC-MS/MS, using a BSA column, is a simple and effective quantitative analysis method for CPLA in serum. (C) 2008 Elsevier B.V. All rights reserved

    DOI: 10.1016/j.jchromb.2008.06.035

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  • Effect of electron irradiation on nanogroove-networked single-crystalline and dendritic polycrystalline platinum nanosheets prepared from lyotropic surfactant liquid-crystal templates

    Takumi Yoshimura, Masafumi Uota, Takeshi Kuwahara, Daisuke Fujikawa, Hideya Kawasaki, Go Sakai, Tsuyoshi Kijima

    MATERIALS RESEARCH BULLETIN   43 ( 5 )   1282 - 1290   2008年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    Using transmission electron microscopy (TEM) electron irradiation effects were studied for nanogroove-network structured single-crystalline and dendritic polycrystalline Pt nanosheets 50-60 nm in size. These two nanosheets with nearly the same average groove-width or dendritic spacing of 1.3-1.4 nm were prepared from the mixed and single surfactant liquid crystalline templates, respectively. On exposure to electron beam for 20 min at the acceleration voltage of 200 kV, the nanogrooved nanosheets were morphologically little affected, but the dendritic ones were transformed into less branched polycrystalline structures with spacings distributed around similar to 1.7 nm. The shape transformation of the latter occurred by the combined mechanism of segmental migration and atomic diffusion. These observations indicate that the nanogrooved Pt nanosheets are highly stabilized by the grooved but crystallographically continuous Pt framework, leading to their extremely high thermo-resistance, in marked contrast to the polycrystalline dendritic structures constructed of crystallographically discontinuous linkages of nanoblocks. (C) 2007 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.materresbull.2007.05.019

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  • Structure analysis of insoluble organic pigments by mass spectrometry with various ionization methods

    Shigehiro Asai, Kenichi Fujita, Masayuki Kubota, Michiko Kanai, Hideya Kawasaki, Ryuichi Arakawa

    BUNSEKI KAGAKU   57 ( 4 )   265 - 271   2008年4月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC ANALYTICAL CHEMISTRY  

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  • MALDI-MS Analysis of Ultrasonic Degradations of Uniform PMMA

    Yoshiki Takeda, Hideya Kawasaki, Takehiro Watanabe, Koichi Ute, Ryuichi Arakawa

    POLYMER JOURNAL   40 ( 8 )   682 - 683   2008年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SOC POLYMER SCIENCE JAPAN  

    DOI: 10.1295/polymj.PJ2008019

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  • Gold-nanoparticle-supported silicon plate with polymer micelles for surface-assisted laser desorption/ionization mass spectrometry of peptides 査読

    KAWASAKI Hideya, Akira Tarui, Takuma Taiko, Takehiro Watanabe, Tetsu Yonezawa, Ryuichi Arakawa

    Journal of Nanoscience and Nanotechnology   9, 159-164   2008年

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  • P17 EO-POブロックコポリマーの超音波分解物の質量分析(第I部,ポスター発表)

    岡林 真義, 渡辺 健宏, 西本 ゆかり, 小澤 智行, 川崎 英也, 荒川 隆一

    ソノケミストリー討論会講演論文集   17   74 - 75   2008年

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    記述言語:日本語   出版者・発行元:日本ソノケミストリー学会  

    It was reported by MALDI-MS combined with an ultrasonic technique that the ultrasonic degradation (UD) of polyethylene glycol (PEG) homopolymers occurred preferentially near the center of polymer chains. In this study, the UD products of di- and tri-block copolymers, poly(ethylene oxide)(EO)-poly(propylene oxide)(PO)(EO: Mw=5,200, PO: Mw=1,700), EO-PO(EO: Mw=2,700, PO: Mw=5,500) and EO-PO-EO(EO: Mw=4,000, PO: Mw=2,000) were analyzed by both MALDI-MS and LC-APCI-MS to determine the repeat units and the end group structures. The results showed that the block copolymers above underwent the selective breaking near the junction of the EO and PO blocks during UD, not near the center of the polymer chains.

    DOI: 10.20577/pamjss.17.0_74

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  • Platinum nanoflowers for surface-assisted laser desorption/ionization mass spectrometry of biomolecules

    Hideya Kawasaki, Tetsu Yonezawa, Takehiro Watanabe, Ryuichi Arakawa

    JOURNAL OF PHYSICAL CHEMISTRY C   111 ( 44 )   16278 - 16283   2007年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    No-template synthesis of surface clean platinum nanomaterials with thin projections (petals) on the Pt nanoparticle surface, termed Pt nanoflowers, has been developed, and Pt nanoflowers have achieved superior performance on surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) of biomolecules. With this new material, one can obtain high-resolution mass spectra with lower laser energy and smaller sample amounts, and no organic matrix is needed for laser desorption/ionization. The mass spectra also have fewer obstacle peaks at the lower m/z region. Furthermore, this novel substrate is quite stable against aging and showed no sweet-spot problems, that is, equal sensitivity on the whole substrate surface. Various biomolecules, including peptides and phospholipids, were examined, and Pt nanoflowers showed good performance for matrix-free laser desorption/ionization MS of these materials.

    DOI: 10.1021/jp075159d

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  • Self-organization of surfactant-metal-ion complex nanofibers on graphite surfaces and their application to fibrously concentrated platinum nanoparticle formation

    Hideya Kawasaki, Masafumi Uota, Takumi Yoshimura, Daisuke Fujikawa, Go Sakai, Ryuichi Arakawa, Tsuyoshi Kijima

    LANGMUIR   23 ( 23 )   11540 - 11545   2007年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We report the fabrication of self-organized surfactant nanofibers containing platinum ions on a highly oriented pyrolytic graphite (HOPG) surface from mixed solutions of hexadecyltrimethylammonium hydroxide (C16TAOH) and hydrogen hexachloroplatinate (IV) (H2PtCl6). The fibrous surfactant self-assembly was stable in air, even after being soaked in water, in contrast to surfactant hemicylindrical micelles, which are stable only at graphite/solution interfaces. The results show that the graphite surface served as an essential template for the specific formation of fibrous surfactant self-assemblies. In addition, when surfactant nanofibers containing metal ions were treated with hydrazine, platinum nanoparticles concentrated in the nanofibers formed on the HOPG surface. We also prepared surfactant nanofibers containing gold ions on HOPG surfaces and formed gold nanoparticles in the nanofibers.

    DOI: 10.1021/la701020s

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  • Fabrication of submillimeter-sized gold plates from thermal decomposition of HAuCl4 in two-component ionic liquids

    Hideya Kawasaki, Tetsu Yonezawa, Kouhei Nishimura, Ryuichi Arakawa

    CHEMISTRY LETTERS   36 ( 8 )   1038 - 1039   2007年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHEMICAL SOC JAPAN  

    We first report the fabrication of submillimeter-sized Au plates (up to about I mm in size) through the simple thermal decomposition of HAUCl(4) in two-component ionic liquids of 1-butyl-3-methylimidazolium hexafluorophosphate (C4ImPF6) and 1-octyl-3-methylimidazolium hexafluorophosphate (C8ImPF6), which were about ten times larger sizes than those from the single-component ionic liquid of the either.

    DOI: 10.1246/cl.2007.1038

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  • Mass spectrometric analysis for high molecular weight synthetic polymers using ultrasonic degradation and the mechanism of degradation

    Hideya Kawasaki, Yoshiki Takeda, Ryuichi Arakawa

    ANALYTICAL CHEMISTRY   79 ( 11 )   4182 - 4187   2007年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We have investigated ultrasonic degradations of poly( ethylene oxide) ( PEG) and poly( methyl methacrylate) ( PMMA) in aqueous media by means of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). The ultrasonic degradation of polymers was monitored as a function of ultrasonication duration to examine the structural details of ultrasonic degradation polymers. PEG solution ultrasonication produced five types of oligomers ((M) over bar similar to 1000 Da) with different end groups, irrespective of the initial average molecular masses (M = 2, 6, 20, and 2000 kDa). Several degradation pathways with free radical reactions have been suggested to explain these degradation products: the ultrasonic degradation of PEG is initiated by breaking of the C-O bond in the PEG chain, generating polymeric radicals with two terminal groups, i.e., X center dot( similar to CH2CH2 center dot) and Y center dot(similar to CH2CH2O center dot), followed by termination with extraction or release of a hydrogen atom. However, PMMA ((M) over bar = 1630 Da) ultrasonication generated only one type of degradation oligomer, which has a hydrogen group at both ends, the same as that of the original oligomer. It has been suggested that the presence of the radical terminal groups X center dot(similar to CH2 center dot) and Y center dot(similar to(CH3) CCOO(CH3) C center dot) is due to selective C-C bond breaking in the chain during the ultrasonic degradation of PMMA. The MALDI-TOFMS combined with the ultrasonic degradation technique (UD/MALDI-TOFMS) developed in this study could be extended to the analysis of synthetic polymer structures with high molecular weights.

    DOI: 10.1021/ac062304v

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  • Influence of the counterions of cetyltrimetylammonium salts on the surfactant adsorption onto gold surfaces and the formation of gold nanoparticles

    Hideya Kawasaki, Kouhei Nishimura, Ryuichi Arakawa

    JOURNAL OF PHYSICAL CHEMISTRY C   111 ( 6 )   2683 - 2690   2007年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We report the effects of counterion species on the adsorption of cetyltrimetyl ammonium salts (C16TAX) onto gold surfaces and the subsequent formation of gold nanoparticles in the C16TAX surfactant solution. The surfactant adsorption onto gold surfaces was examined by using quartz crystal microbalance (QCM) and atomic force microscopy (AFM). The counterion species (X) examined in this study were as follows: X = Br-, Cl-, NO3, F-, OH-, and SO42-. The adsorption onto the gold surface depended on the counterion species of C16TAX-the frequency shift of QCM decreased in the following order: X = Br- &gt; NO3- approximate to SO42- &gt; Cl- &gt; F- &gt; OH-. The chemical reduction of gold(III) in the surfactant solutions of C16TAX with use of 2,2'-iminodiethanol as a mild reducing agent produced anisotropic gold nanoparticles, depending on the surfactant counterion. The high-affinity adsorption of Br, NO3, and Cl on gold surfaces produced anisotropic gold nanoparticles, while only spherical gold nanoparticles were obtained for weakly bound counterions such as SO42-, F-, and OH-. In contrast, the chemical reduction with hydrazine proceeded rapidly such that the shape of the gold nanoparticles was uncontrollable; this resulted in the formation of spherical gold nanoparticles, irrespective of the surfactant counterion.

    DOI: 10.1021/jp066963n

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  • Synthesis of nanogroove-network-structured platinum nanosheets and their carbon-supported forms using a mixed-surfactant templating approach

    Go Sakai, Takumi Yoshimura, Shusaku Isohata, Masafumi Uota, Hideya Kawasaki, Takeshi Kuwahara, Daisuke Fujikawa, Tsuyoshi Kijima

    ADVANCED MATERIALS   19 ( 2 )   237 - +   2007年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    Single-crystalline Pt nanosheets with a nanogroove-network structure (see figure) are reported. A method of loading the nanogrooved Pt nanosheets on a carbon support is also described and the resulting nanogroove-networked Pt on a carbon support (Pt/C) is demonstrated to exhibit fairly high electrocatalytic activity for oxygen reduction, which is of interest for fuel cells.

    DOI: 10.1002/adma.200601127

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  • Characterization of polyether mixtures using thin-layer chromatography and matrix-assisted laser desorption/ionization mass spectrometry 査読

    Takehiro Watanabe, Hideya Kawasaki, Takashi Kimoto, Ryuichi Arakawa

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY   21 ( 5 )   787 - 791   2007年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JOHN WILEY & SONS LTD  

    Thin-layer chromatography (TLC) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) were combined to achieve characterization of polyether mixtures. Three polyethers, polyethylene glycol (PEG), polypropylene glycol (PPG) and polytetramethylene glycol (PTMG), or mixtures of these compounds, were studied. One shortcoming of mixture analysis of synthetic polymers using MALDI-MS is that individual polymers in the mixture may display different detection sensitivities. For example, the MALDI mass spectrum of an equimolar mixture of PEG, PPG and PTMG displayed a high intensity of PPG ions, while no PTMG ions were detectable; however, PTMG ions were detected after the mixture had been separated by TLC. This combined TLC and MALDI-MS analysis of a PPG polymer bearing reactive epoxy groups showed that the polymer contained byproducts with different end-groups. These byproducts were identified as chloro-substituted polymers formed during polymer synthesis. Our study shows TLC to be a rapid and low-cost separation technique, and that it can be combined with MALDI-MS to achieve effective analysis of synthetic polymers. Copyright (c) 2007 John Wiley & Sons, Ltd.

    DOI: 10.1002/rcm.2896

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  • Characterization of polyether mixtures using thin-layer chromatography (TLC) and MALDI-MS 査読

    KAWASAKI Hideya, K.Watanabe, R.Ryuichi

    Rapid Communications in Mass Spectrometry   21, 787-791   2007年

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  • 液晶/カーボン混合系還元反応による白金架橋ナノワイヤ粒子の生成機構

    魚田 将史, 林 祐一, 吉村 巧己, 川崎 英也, 酒井 剛, 木島 剛

    日本セラミックス協会 年会・秋季シンポジウム 講演予稿集   2007 ( 0 )   681 - 681   2007年

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:公益社団法人 日本セラミックス協会  

    先に報告した白金架橋ナノワイヤ/カーボン粒子の生成機構を解明するためXRDをもちいて液晶構造の検討を行った。その結果、白金粒子の形態が液晶中の含有水量に依存し、電気化学特性にも影響することがわかった。

    DOI: 10.14853/pcersj.2007F.0.681.0

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  • Mode of interaction of two fluorinated-hydrogenated hybrid amphiphiles with dipalmitoylphosphatidylcholine (DPPC) at the air-water interface

    Kazuki Hoda, Hideya Kawasaki, Norio Yoshino, Chien-Hsiang Chang, Yoko Morikawa, Gohsuke Sugihara, Osamu Shibata

    COLLOIDS AND SURFACES B-BIOINTERFACES   53 ( 1 )   37 - 50   2006年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Two-component Langmuir monolayers formed on 0.02 M Tris buffer solution (pH 7.4) with 0.13 M NaCl at 298.2 K were investigated for two different fluorinated-hydrogenated hybrid amphiphiles (F6PH5PPhNa and F8PH5PPhNa or F6 and F8, respectively) with DPPC. Surface pressure (pi), surface potential (Delta V) and dipole moment (mu(perpendicular to) as a function of molecular surface area (A) were measured by employing the Whithelmy method and an ionizing electrode method. From the A- and Delta V-X-F6 (or X-F8) curves, partial molecular surface area (PMA) and apparent partial molecular surface potential (APSP) were determined as a function of surface mole fraction (X-Fn) at discrete surface pressures. Then, the behavior of occupied surface areas and surface potentials of the respective components could be made clearer. Compressibility (C-s), elasticity (C-s(-1)), and excess Gibbs energy (Delta G((ex))) as a function of X-F6 (or X-F8) were estimated at definite pressures. These physico-chemical parameters were found to reflect the mechanical strength of monolayer films formed. The regular solution theory being applied to Delta G((ex)), the activity coefficients (f) as well as the interaction parameter (I-p) between DPPC and two hybrid amphiphiles in the binary monolayers were evaluated. I-p values thus obtained indicated that F8 molecules interact more strongly with DPPC molecules than F6. Moreover, in order to better understand the morphological monolayer state, Langmuir-Blodgett (LB) films made from DPPC and fluorinated-hydrogenated hybrid amphiphiles were examined by atomic force microscopy (AFM). The miscibility of the two components in the monolayer state is evidenced by these thermodynamic quantities and AFM observations. Furthermore, AFM images demonstrated that F8 could more effectively disperse the ordered domains of DPPC than F6. (C) 2006 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.colsurfb.2006.07.019

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  • Direct observation of dynamic shape transformation and coalescence in platinum nanosheets on graphite surface at room temperature by time-resolved AFM

    Hideya Kawasaki, Go Sakai, Tsuyoshi Kijima

    APPLIED SURFACE SCIENCE   253 ( 3 )   1512 - 1516   2006年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The shape transformation of platinum (Pt) nanosheets with a uniform thickness of as thin as 3.5 +/- 1 nm supported on graphite was investigated by in situ atomic force microscopy (AFM). The AFM observations revealed the shape transformation and the coalescence in preferred directions for the Pt nanosheets at room temperature (25 degrees C), which is much lower than the melting point of bulk metallic platinum (1769 degrees C). The behavior may be attributed to the high surface energy for the edge parts of Pt nanosheets with the small curvature of the nanometer scale. (c) 2006 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.apsusc.2006.02.032

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  • Mode of interaction of ganglioside Langmuir monolayer originated from echinoderms: Three binary systems of ganglioside/DPPC, ganglioside/DMPE, and ganglioside/cholesterol

    Kazuki Hoda, Yuriko Ikeda, Hideya Kawasaki, Koji Yamada, Ryuichi Higuchi, Osamu Shibata

    COLLOIDS AND SURFACES B-BIOINTERFACES   52 ( 1 )   57 - 75   2006年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The surface pressure (pi)-area (A), the surface potential (Delta V)-A, and the dipole moment (mu(perpendicular to))-A isotherms were obtained for monolayers made from a ganglioside originated from echinoderms [Diadema setosum ganglioside (DSG-1)], dipalmitoylphosphatidylcholine (DPPC), dimyristoylphosphatidylethanolamine (DMPE), cholesterol (Ch), and their combinations. Monolayers spread on several different substrates were investigated at the air/water interface by the Wilhelmy method, ionizing electrode method, fluorescence microscopy (FM) and atomic force microscopy (AFM). Surface potentials (Delta V) of pure components were analyzed using the three-layer model proposed by Demchak and Fort [R.J. Demchak, T. Fort, J. Colloid Interface Sci. 46 (1974) 191-202]. The new finding was that DSG-1 was stable and showed a liquid-expanded film and that its monolayer behavior of Delta V was sensitive for the change of the NaCl concentration in the subphase. Moreover, the miscibility of DSG-1 and three major lipids in the two-component monolayers was examined by plotting the variation of the molecular area and the surface potential as a function of the DSG-1 molar fraction (XDSG-1), using the additivity rule. From the A--XDSG-1 and Delta V-m-XDSG-1 plots, partial molecular surface area (PMA) and apparent partial molecular surface potential (APSP) were determined at the discrete surface pressure. The PMA and APSP with the mole fraction were extensively discussed for the miscible system. The miscibility was also investigated from the two-dimensional phase diagrams. Furthermore, a regular surface mixture, for which the Joos equation was used for the analysis of the collapse pressure of two-component monolayers, allowed calculation of the interaction parameter (xi) and the interaction energy (-Delta epsilon) between them. The observations using fluorescence microscopy and AFM image also provide us the miscibility in the monolayer state. (c) 2006 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.colsurfb.2006.07.006

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  • One-dimensional assemblies of platinum nanoparticles on a graphite surface using nonionic/ionized mixed hemicylindrical micelle templates

    Hideya Kawasaki, Masafumi Uota, Takumi Yoshimura, Daisuke Fujikawa, Go Sakai, Tsuyoshi Kijima

    JOURNAL OF COLLOID AND INTERFACE SCIENCE   300 ( 1 )   149 - 154   2006年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACADEMIC PRESS INC ELSEVIER SCIENCE  

    One-dimensional (1-D) self-assemblies of Pt nanoparticles on a graphite surface have been synthesized via a template-directed sintering process of individual nanoparticles, using nonionic/cationic mixed hemicylindrical micelle templates of dodecyldimethylamine oxide surfactant at graphite/solution interfaces. The dimension and morphology of Pt nanoparticles can be widely controlled by the concentration of Pt ions equivalent to the mixing ratio of nonionic and cationic species in the surfactant micelle. This approach could be extended to fabricate a wide range of self-assembling metallic nanostructures on surfaces using various nonionic/cationic mixed micelle-like self-assemblies carrying metal ions at interfaces, while providing a fundamental insight into a 1-D self-assembly from individual nanoparticles. (c) 2006 Elsevier Inc. All rights reserved.

    DOI: 10.1016/j.jcis.2006.03.040

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  • Reversible micelle-vesicle conversion of oleyldimethylamine oxide by pH changes

    H Maeda, S Tanaka, Y Ono, M Miyahara, H Kawasaki, N Nemoto, M Almgren

    JOURNAL OF PHYSICAL CHEMISTRY B   110 ( 25 )   12451 - 12458   2006年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    A preliminary study on the reversible micelle-vesicle conversion of oleyldimethylamine oxide [Kawasaki, H. et al. J. Phys. Chem. B. 2002, 106, 1524] is extended in the present study. In the presence of 0.01 M NaCl at a surfactant concentration of 0.05 M, a micelle-to-vesicle conversion with increasing degree of ionization alpha takes place in the following sequence: growth of fibrous micelle (alpha &lt; 0.2), a fused network (alpha similar to 0.3), fibrous micelles + (perforated) vesicles (alpha = 0.4), and vesicles + lamellae (alpha = 0.5). Viscoelasticity correspondingly varies from the Maxwell-type behavior of the entangled network of fibrous micelles to the gel-like behavior of vesicle suspensions, via a fluid solution-like behavior of the fused network. This phase sequence is in contrast with the case of no added salt where no branching of micelles is observed, and long micelles and bilayers (vesicles + lamellae) coexist at alpha = 0.5. In water, a state of the lowest viscoelasticity occurs around alpha = 0.2 for both surfactant concentrations 0.05 and 0.15 M. Synergism between protonated and nonprotonated amine oxide headgroups is observed despite low ionic strengths. From the time course of the reversible micelle-vesicle conversion, vesicles seem to be formed from threadlike micelles within 25 h according to the shear moduli, while a longer conversion time is suggested by a flow property (viscosity). Shear thickening behavior is observed at alpha = 0.2 and 0.4 in 0.01 M NaCl but not in water.

    DOI: 10.1021/jp056967c

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  • Charge-induced unilamellar vesicle formation and phase separation in solutions of di-n-decylmethylamine oxide

    H Kawasaki, VM Garamus, M Almgren, H Maeda

    JOURNAL OF PHYSICAL CHEMISTRY B   110 ( 20 )   10177 - 10185   2006年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    A double- tail amine oxide surfactant, di- n- decylmethylamine oxide ( 2C10MAO), was prepared, and the effects of protonation on aggregate structure were examined by small- angle neutron scattering ( SANS), cryotransmission electron microscopy ( cryo- TEM), turbidity, electric conductivity, and solubilization of an oil-soluble dye at various degrees of neutralization, X, defined as the mole ratio of HCl/ 2C10MAO. The surfactant makes an L-2 phase in the nonprotonated state ( X = 0) in water. The L-2 phase is in equilibrium with an aqueous L-1 phase. On protonation, unilamellar vesicles ( ULVs) are formed over a wide range of compositions ( 0.05 &lt; X&lt; 0.4- 0.5 at C = 10 mM) as observed by cryo- TEM. At X = 0.2, the ULV is stable over a wide concentration range ( 3 mM &lt;= C &lt; 0.1 M), but an L-alpha phase replaces the vesicle phase at C &gt; 0.1 M. SANS results show that the mean radius of the ULV is about 25 nm and the bilayer thickness is about 2 nm, consistent with the extended configuration of the alkyl chains of the surfactant. An important contribution to the enhanced stability of the bilayer structures over the L-2 phase is suggested to be the translational entropy of the counterions. The enhanced stability of the bilayers diminishes as the counterion concentration increases either by an increase of X or by the addition of a salt. When the counterion concentration exceeds a critical value, the ULV solutions transform into the L-2 phase ( or L-2/ L-1 two- phase system at low surfactant concentrations). The critical composition X* is about 0.4- 0.5 in water, but it is below 0.4 in D2O. The critical NaCl concentration is below 5 mM at X = 0.2. The stability of ULVs against multilamellar vesicles is ascribed partly to undulation forces and partly to the adjustable nature of the spontaneous curvature of amine oxide monolayers. The characteristics of the ULV of the surfactant remain the same within a temperature range 25 - 50 degrees C at X = 0.2. An iridescent lamellar phase and possibly an L-3 phase were observed in a very narrow X range ( 0 &lt; X &lt; 0.02) prior to the vesicle phase.

    DOI: 10.1021/jp061335r

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  • Effects of L-arginine on aggregates of fatty-acid/potassium soap in the aqueous media

    A Hirai, H Kawasaki, S Tanaka, N Nemoto, M Suzuki, H Maeda

    COLLOID AND POLYMER SCIENCE   284 ( 5 )   520 - 528   2006年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    In the present study, we investigated the effects of L-arginine on aggregates of fatty acid/fatty soap in the aqueous media as a function of pH, by means of hydrogen ion titration, viscoelastic measurement, cryotransmission electron microscopy and phase contrast microscopy. We found out that L-arginine effectively inhibits the oil droplet growth of oleic acid or octanoic acid. The effect is explained in terms of the adsorption of arginine at the microscopic drop surface, or at the oil/water microinterface through the hydrophobic effect assisted by the hydrogen bonds between carboxyl group of fatty acid and carboxylate of arginine. As to the crystallization of lauric acid at temperatures below the melting point of the hydrocarbon chain, arginine is not effective. In addition, we also found out that the strong binding of arginine cation to anionic oleate micells induces the dominant micellar growth. L-arginine has been used in many refolding systems to suppress protein aggregation. These effects of L-arginine on the aggregates of fatty acid/fatty soap in the aqueous media observed in the present study is expected to form a basis to the specific function displayed in the protein refolding.

    DOI: 10.1007/s00396-005-1423-1

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  • Mode of interaction of amphiphilic alpha-helical peptide with phosphatidylcholines at the air-water interface

    H Nakahara, S Nakamura, T Hiranita, H Kawasaki, S Lee, G Sugihara, O Shibata

    LANGMUIR   22 ( 3 )   1182 - 1192   2006年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Surface pressure (pi)-, surface potential (AV)-, and dipole moment (mu(perpendicular to))-area (A) isotherms and morphological behavior were examined for monolayers of a newly designed 18-mer amphiphilic alpha-helical peptide (Hel 13-5), DPPC, and DPPC/egg-PC (1:1) and their combinations by the Wilhelmy method, ionizing electrode method, fluorescence microscopy (FM), and atomic force microscopy (AFM). The newly designed Hel 13-5 showed rapid adsorption into the air-liquid interface to form interfacial films such as a SP-B function. Regardless of the composition and constituents in their multicomponent system of DPPC/egg-PC, the collapse pressure (pi(c); -42 mN m(-1)) was constant, implying that Hel 13-5 with the fluid composition of egg-PC is squeezed out of Hel 13-5/DPPC/egg-PC monolayers accompanying a two- to three-dimensional phase transformation. FM showed that adding a small amount of Hel 13-5 to DPPC induced a dispersed pattern of ordered domains with a "moth-eaten" appearnce, whereas shrinkage of ordered domains in size occurred for the DPPC/egg-PC mixture with Hel 13-5. Furthermore, AFM indicated that (i) the intermediate phase was formed in pure Hel 13-5 systems between monolayer states and excluded nanoparticles, (ii) protrusions necessarily located on DPPC monolayers, and (iii) beyond the collapse pressure of Hel 13-5, Hel 13-5 was squeezed out of the system into the aqueous subphase. Furthermore, hysteresis curves of these systems nicely resemble those of the DPPC/SP-B and DPPC/SP-C mixtures reported before.

    DOI: 10.1021/la0524925

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  • Modification of gold nanorods using phospatidylcholine to reduce cytotoxicity

    H Takahashi, Y Niidome, T Niidome, K Kaneko, H Kawasaki, S Yamada

    LANGMUIR   22 ( 1 )   2 - 5   2006年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Hexadecyltrimethylammonium bromide (CTAB), which is necessary for the preparation of gold nanorods (NRs), was extracted from a NR solution into a chloroform phase containing phosphatidylcholine (PC). After three extractions, the zeta potential of the NRs remained positive, but its magnitude decreased from +67 +/- 1 to +15 +/- 1 mV. Transmission electron microscopy and energy-dispersive X-ray analysis indicated that the NRs were passivated with PC. The PC layer on the NR surface contributed to the prevention of NR aggregation. The PC-passivated NRs showed low cytotoxicity in comparison with twice-centrifuged NRs. It was shown that a negligible amount of CTAB was dispersed in the NR solution after the extraction. The extraction using a chloroform phase containing PC was found to be a convenient way of replacing the CTAB with alternative capping agents such as PC. This is a key technique for preparing functional NRs that can have practical applications.

    DOI: 10.1021/la0520029

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  • Single-crystalline platinum nanosheets from nonionic surfactant 2-D self-assemblies at solid/aqueous solution interfaces

    H Kawasaki, M Uota, T Yoshimura, D Fujikawa, G Sakai, M Annaka, T Kijima

    LANGMUIR   21 ( 24 )   11468 - 11473   2005年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Single-crystalline platinum nanosheets have been prepared via a new methodology based on the chemical reduction of a platinum salt (H2PtCl6) with hydrazine at a graphite/solution interface, using polyoxyethylene (20) sorbitan monostearate (Tween 60) based self-assembly (hemicylindrical micelle) templates. The platinum nanosheets with a uniform thickness of as thin as 3.5 +/- 1 nm are surface-smooth and continuous over relatively large length scales of micrometer sizes. In striking contrast to the Tween 60 based system, no Pt nanosheets are obtained with nonaethylene glycol monododecyl ether (C12EO9) and polyoxyethylene (23) dodecyl ether (C12EO23). No Pt nanosheets are also obtainable with a laterally homogeneous layer of Tween 60 formed at the silica/solution interface. These results indicate that surfactant Tween 60 molecules with a triple polyoxyethylene structure, as well as their hemicylindrical micelle templates, play an essential role for the formation of the Pt nanosheets. It is also suggested that the interfacially directed growth of Pt metals within the aqueous shells of the Tween 60 hemicylindrical micelles induces the thin Pt crystals as thick as the aqueous shells. The present approach could be extended to prepare a wide range of novel nanostructures of noble metals, using various micelle-like self-assemblies at interfaces.

    DOI: 10.1021/la051247i

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  • Effects of micelle-to-vesicle transitions on the degree of counterion binding

    Y Ono, H Kawasaki, M Annaka, H Maeda

    JOURNAL OF COLLOID AND INTERFACE SCIENCE   287 ( 2 )   685 - 693   2005年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACADEMIC PRESS INC ELSEVIER SCIENCE  

    Effects of micelle-to-vesicle transitions on the degree of counterion binding (beta) were investigated on three systems. For the concentration-dependent micelle-to-vesicle transition in the didodecyldimethylammonium bromide (DDAB)/water system, in the region of coexistent micelles and vesicles, less than 3 mM, the beta values increased significantly with DDAB concentration: beta(0.07 mM) = 0.35 and beta (3 mM) = 0.93. In the coexistent region, activities of the bromide ion, a(Br), were almost independent of the DDAB concentration, suggesting the pseudo-phase nature of both micelles and vesicles. In the concentration-dependent vesicle-to-lamellar transition region above 5 mM, where multilamellar vesicles were prevailing, on the other hand, the values were only little affected by this transition. This suggests that the increase in the layer number of DDAB multilamellar vesicles scarcely affects the values. This Was also Supported by the fact that the destruction of multilamellar vesicles by ultrasonication did not change the P values. These results strongly suggest that the inner and Outer monolayers of DDAB multilamellar vesicles are characterized by similar 6 values. The second system, cetyltrimethylammonium bromide (CTAB)/DDAB mixtures. showed composition-dependent transitions depending on the mole fraction of DDAB X-DDAB: spherical micelles (0 &lt; X-DDAB &lt; 0.2) -&gt; rodlike micelles (0.2 &lt; X-DDAB &lt; 0.4) -&gt; vesicles (0.6 &lt; X-DDAB &lt; 1). Values of beta increased with both the sphere-to-rodlike micelle transition and the micelle-to-vesicle transition. The increase in the value was larger for the latter than for the former transition. Little effects Of Ultrasoflication on was also observed for the multilamellar vesicles of CTAB/DDAB mixtures. In the third system of the mixtures of two single chain surfactants, protonated and non-protonated of oleyldimethylamine oxide, the dependence of beta on the degree of ionization (alpha) can be well described with a theoretical curve, derived on the basis of the linear relation between the surface charge density and the alpha value, despite the occurrence of the micelle-to-vesicle transition. (c) 2005 Elsevier Inc. All rights reserved.

    DOI: 10.1016/j.jcis.2005.02.021

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  • Protonation-induced structural change of lyotropic liquid crystals in oley- and alkyldimethylamine oxides/water systems

    H Kawasaki, A Sasaki, T Kawashima, S Sasaki, R Kakehashi, Yamashita, I, K Fukada, T Kato, H Maeda

    LANGMUIR   21 ( 13 )   5731 - 5737   2005年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Lyotropic phase behavior of the nonionic and the half-ionized oleyldimethylamine oxide (O1DMAO)/water systems was investigated using polarized light microscopy, small-angle X-ray diffraction, and differential scanning calorimetry. Nonionic O1DMAO formed isotropic micellar solution, nematic, hexagonal, cubic, and lamellar liquid crystalline phases as the surfactant concentration increased. In contrast, half-ionized O1DMAO (i.e., 1:1 mixture of the nonionic and the protonated species) had a greater tendency to form bilayer structures, and the phase diagram became quite similar to those of double-chained ionic surfactants rather than single-chained ones, despite the introduction of positive charges to the nonionic one. The preference of the bilayer structures in the half-ionized O1DMAO was interpreted in terms of the dimers stabilized by the hydrogen bond between the nonionic and protonated species. For alkyldimethylamine oxides with a saturated hydrocarbon chain (CnDMAO, chain length: n = 14, 16, and 18), the phase sequence of lyotropic liquid crystals was hardly affected by the protonation, but an elongation of the cylinders of the hexagonal phase was observed for the half-ionized C14DMAO. Consequently, it can be considered that the dominant bilayer formation of the half-ionized O1DMAO is attributed to the combined effect of the hydrogen-bonded dimer formation and the cis-double-bond configuration of the alkyl chain.

    DOI: 10.1021/la0503496

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  • Effects of ammonium salts and anionic amphiphiles on the photochemical formation of gold nanorods

    Y Niidome, K Nishioka, H Kawasaki, S Yamada

    COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS   257-58   161 - 164   2005年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The effects of ammonium salts and anionic amphiphiles on the formation and morphology of gold nanorods (NRs) in hexadecyltrimethylammonium bromide (CTAB) solutions were investigated. The addition of a small amount of tetrahexylammonium bromide (THAB) increased the aspect ratio of NRs. while an excess of THAB or tetradodecylammonium bromide (TDAB) decreased the aspect ratio, and concomitantly increased the formation of spherical gold nanoparticles. In contrast, the addition of anionic amphiphiles forming hydrophobic ion-complexes with CTAB did not decrease the aspect ratio, but suppressed the formation of NRs. These results could be attributed to the change in the adsorbed layer of CTAB on the gold NRs. (c) 2004 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.colsurfa.2004.10.015

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  • Temperature-induced sedimentation to dispersion of ionic vesicles

    H Kawasaki, M Miyahara, M Almgren, G Karlsson, H Maeda

    JOURNAL OF COLLOID AND INTERFACE SCIENCE   284 ( 1 )   349 - 353   2005年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACADEMIC PRESS INC ELSEVIER SCIENCE  

    We present a temperature-induced sedimentation/dispersion transition of ionic vesicles in the system of alkyldimethylamine oxide hemihydrochloride (CnDMAO.1/2HCl) with a hydrocarbon chain length of 12-16 (n = 12,14, and 16) and sodium 2-naphthalenesulfonate (NaNphS). The temperature-sensitive sedimentation/dispersion of ionic vesicles took place around a temperature of 50 degrees C, which was weakly dependent on the alkyl chain length. The combined effect of the thermally induced dissociation of the counterions from the vesicle and a hydrogen bonding between the nonionic and the cationic head groups is likely to be responsible for this unique behavior. (c) 2004 Elsevier Inc. All rights reserved.

    DOI: 10.1016/j.jcis.2004.09.078

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  • Complex formation in alkyldimethylamine oxide/sodium palmitate/water mixtures

    S Tanaka, H Kawasaki, H Maeda

    JOURNAL OF COLLOID AND INTERFACE SCIENCE   283 ( 1 )   238 - 244   2005年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACADEMIC PRESS INC ELSEVIER SCIENCE  

    The complex formation between nonionic alkyldimethylamine oxide (CnDMAO, n = 14, 16, and 18) and sodium palmitate (NaPa) in the solid phase of CnDMAO/NaPa mixtures and the dependence of the interaction parameter of the regular solution theory (RST) on the mixed micelle composition of C16DMAO/NaPa mixtures were investigated. The dissolution temperature showed a maximum at a NaPa mole fraction X*(Pa) of 0.3-0.4 for C16DMAO/NaPa and 0.2 for C18DMAO/NaPa. The compositions of the complexes suggested by X*(Pa) are C 16DMAO: NaPa = 3:2 or 2:1 and C18DMAO:NaPa = 4: 1. The composition X*(Pa) depended on the chain length of the amine oxides.The maximum was not observed in the case of the C14DMAO/NaPa/water system. In the range 0.7 less than or equal to X*(Pa) less than or equal to 1.0, dissolution temperature depression was observed with decreasing X-Pa. The dissolution temperature depression was analyzed by taking into account the nonideal behavior in the mixed micelles and the counterion binding on the mixed micelle surface. The negative values were obtained for all three mixed systems. It was shown that the counterion activity remained practically constant in the range of 0.7 less than or equal to X-Pa less than or equal to 1.0. The cmc values of C16DMAO/NaPa mixtures were determined by pyrene fluorescence measurement. For C16DMAO/NaPa mixtures, the dependence of the RST interaction parameter beta on the mixed micelle composition X-Pa was determined for a wide range (0.2 less than or equal to X-Pa less than or equal to 0.9). In the range 0.2 less than or equal to X-Pa less than or equal to 0.5, the beta values were obtained from an analysis of cmc based on the RST. In the range 0.7 less than or equal to X-Pa less than or equal to 0.9, the beta values were obtained from an analysis of the dissolution temperature depression. From the analysis of the micelle composition dependence of the P values, a short-range attractive interaction between the headgroup of C16DMAO and palmitate anion is suggested. (C) 2004 Elsevier Inc. All rights reserved.

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  • Reversible pH-induced transformation of micellar aggregates between hemicylinders and laterally homogeneous layers at graphite-solution interfaces

    H Kawasaki, M Shinoda, M Miyahara, H Maeda

    COLLOID AND POLYMER SCIENCE   283 ( 4 )   359 - 366   2005年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    pH-induced transformation between a hemicylindrical aggregate and a laterally homogeneous layer at the graphite-solution interface was demonstrated in micellar aggregates of dodecyldimethylamine oxide (C12DMAO) using atomic force microscopy (AFM). Nonionic C12DMAO (pHsimilar to8) and fully-ionized cationic C12DMAO (pHsimilar to1.5) both formed hemicylindrical aggregates on graphite, similar to aggregates formed by many other ionic (or nonionic) surfactants on graphite. However, a laterally homogeneous layer was observed in the case of nearly half-ionized C12DMAO around pHsimilar to4 (a 1:1 mixture of the nonionic and the cationic species). These results indicated that the surface curvature of the C12DMAO aggregates on graphite was the smallest around the degree of ionization alpha=0.5, despite charging up the nonionic hemicylindrical aggregates. Using AFM images and the corresponding force curves, the transformation between the hemicylindrical aggregate and the laterally homogeneous layer was found to be reversible via a change in pH. The formation of the laterally homogeneous layer of nearly half-ionized C12DMAO is explained by hydrogen bond formation between the nonionic and the cationic headgroups.

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  • Properties of Two-component Langmuir Monolayer of Single Chain Perflorinated Carboxylic Acids with Dipalmitoylphosphatidylcholine(DPPC) 査読

    KAWASAKI Hideya, H. Nakahara, S. Nakamura, O. Shibata

    Colloid and Surface B   ”41, 285-298”   2005年

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  • Size-Growth of Gold Nanospheres Induced By the Pulsed-laser Irradiation of Polycation-Gold Nanoparticle Aggregates 査読

    KAWASAKI Hideya, T. Kawasaki, H. Takahashi, Y. Niidome, S. Yamada

    Transactions of the Materials Research Society of Japan   ”30, 571-574”   2005年

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  • Electrophoretic mobility of the polymer-like micelles of tetradecyldimethylamine oxide hemihydrochloride

    H Kawasaki, H Maeda

    COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS   250 ( 1-3 )   479 - 483   2004年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Effects of the surfactant concentration C-d and the NaCl concentration C-s on the electrophoretic mobilities U of the well-characterized polymer-like micelles have been investigated by the electrophoretic light scattering, using tetradecyldimethylamine oxide hemihydrochloride (C14DMAO . 1/2HCl). At the high ionic strength of 0.1 mol kg(-1) NaCl, the electrophoretic mobilities were independent of C-d (5 mM &lt; C-d &lt; 100 mM), despite the concentration-dependent micelle growth of the polymer-like micelles. This suggests that the electrophoretic mobility of the polymer-like micelle at high ionic strengths is independent of the contour length (i.e., the molecular weight), as found on linear polyelectrolytes. Somewhat surprisingly, the entanglements of the polymer-like micelles gave small effect on the electrophoretic mobilities in the examined range of the surfactant concentration above an overlap concentration. The mobilities of the polymer-like micelle decreased with rootC(s) in a single exponential manner in the range of C-s front 0.02 to 0.3 mol kg(-1). It is suggested that the cylinder model can be applied to the electrophoretic mobilities of the polymer-like micelles at high ionic strengths (i.e. a free-draining behavior), since the persistence length of the polymer-like micelle (similar to20 nm) is much larger than the Debye length at high ionic strength. (C) 2004 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.colsurfa.2004.04.097

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  • Micelle-vesicle transition of oleyldimethylamine oxide in water

    M Miyahara, H Kawasaki, VM Garamus, N Nemoto, R Kakehashi, S Tanaka, M Annaka, H Maeda

    COLLOIDS AND SURFACES B-BIOINTERFACES   38 ( 3-4 )   131 - 138   2004年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We studied the effects of the degree of ionization(alpha) and the surfactant concentration (C-d) on the micelle-vesicle transition in salt-free oleyldimethylamine oxide (OlDMAO) aqueous solutions by the dynamic light scattering (DLS), the hydrogen ion titration, the small angle neutron scattering (SANS), the electrophoretic light scattering (ELS) and viscoelastic measurements. From the study of ionization effects, the micelle-vesicle transition was recognized as a change of aggregate size by the DLS measurement; however, the micelle-vesicle transition was not detected both in the ELS measurement and the hydrogen ion titration, suggesting that the electric properties of the worm-like micelles and the vesicles are very similar despite a large difference of shapes between them. From the results of the SANS, the DLS and the viscosity measurements, it was suggested that a concentration-dependent micelle-vesicle transition took place around C-p = 10 mmol kg(-1) for the solutions at alpha = 0.5. In the concentration-range 10 mmol kg(-1) &lt; C-d &lt; 150 mmol kg(-1), the micelles and the vesicles coexisted. In the concentration region (C-d = 10-50 mmol kg(-1)), the vesicle size increased with the surfactant concentration. (C) 2004 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.colsurfb.2004.04.011

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  • Investigation of the stability of graphite particle dispersion and the hemimicelle formation process at graphite/solution interfaces using atomic force microscopy

    H Kawasaki, K Ban, H Maeda

    JOURNAL OF PHYSICAL CHEMISTRY B   108 ( 43 )   16746 - 16752   2004年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    The correlation between the dispersion stability of graphite particles suspended in aqueous solutions of dodecyldimethylhydroxylammonium chloride (C12DMAOH.Cl) and the structure of the adsorption layer on the graphite surface was investigated by a combination of data from AFM images, measurements of interaction forces, an adsorption isotherm, and turbidity measurements of graphite suspensions. A model for the two-step adsorption mechanism was successfully applied to describe the adsorption isotherm. (The first step was the formation of the horizontal adsorbed monolayer, and the second step was the formation of the hemicylindrical aggregate.) It was suggested that there is a transition regime where the horizontal adsorbed monolayer coexists with the hemicylindrical aggregate. A dispersion of graphite particles is unstable in the presence of the horizontal adsorbed monolayer. Surface force measurements suggest that the surface charges of the horizontal adsorbed monolayer are mostly neutralized by the bound counterions. The critical hemimicelle concentration (hmc) was about 0.8 mM, which was about (1)/(10) of the bulk critical micelle concentration (cmc approximate to 6 mM). The hmc value was close to the critical concentration at which the suspension stability started to increase dramatically with the surfactant concentration. We found that a stable dispersion of graphite particles can only be achieved once the hemicylindrical aggregates have formed on the surface at full surface coverage, leading to the development of the electric double layer forces from the positively charged aggregate.

    DOI: 10.1021/jp0488970

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  • Gel shrinking resulting from uneven distribution of ionic micelles between the inside and the outside of the polymer gel network

    AM El Sayed, H Kawasaki, H Maeda

    JOURNAL OF APPLIED POLYMER SCIENCE   93 ( 5 )   2001 - 2006   2004年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JOHN WILEY & SONS INC  

    The volume change of crosslinked nonionic poly (N-isopropylacrylamide) (NIPA) polymer gel immersed in tetradecyldimethylaminoxide (C14DMAO) surfactant solutions at 0.1M NaCl, were investigated to distinguish between binding and nonbinding polymer gel/C14DMAO surfactants. Also, the aggregation behavior of C14DMAO surfactants the inside and the outside the polymer hydrogels has been studied through solubilization of Sudan III dye. For the C14DMAO surfactants at the degrees of ionization (alpha) of 0.5 and 1, they bind to the NIPA gel at low surfactant concentration (C-D) that enhance the gel swelling due mainly to the osmotic pressure contribution from the counter ions (regime I, C-D&lt;10mM). However, the deswelling behavior was observed as the surfactant concentration increases above 10 mM (regime II). The solubilization experiments indicated that the surfactant concentration inside the gel is lower than that outside the gel in the regime 0 11, which may be due to the large micelle size that cannot accommodate the mesh size of the gel. It was suggested that the uneven distribution of the ionic micelles leads to the reduction of the net swelling osmotic pressure of the gel (i.e., the decrease of the gel volume). In the case of the nonionic C14DMAO at alpha = 0, on the other hand, the deswelling behavior was not clearly observed and the surfactant concentration inside the gel and outside the gel was almost identical even at 30 mM. For the nonionic surfactant, it was also found that the gel volume increases with the surfactant concentration at low surfactant concentration less than 1mM. This may be attribute to the dipole-dipole repulsion of N-O headgroups. (C) 2004 Wiley Periodicals, Inc.

    DOI: 10.1002/app.20634

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  • Vesicle formation in oleyldimethylamine oxide/sodium oleate mixtures

    S Tanaka, H Kawasaki, M Suzuki, M Annaka, N Nemoto, M Almgren, H Maeda

    COLLOID AND POLYMER SCIENCE   282 ( 10 )   1140 - 1145   2004年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Vesicle formation in a mixture of oleyldimethylamine oxide (OleylDMAO) and sodium oleate (NaOl) was investigated by viscoelastic measurements and cryoscopic transmission electron micrograph (cryo-TEM) observations. The viscoelastic properties changed with increasing mole fraction of NaOl (X-NaOl) from the Maxwell behavior of OleylDMAO solutions (X-NaOl=0) suggesting a transient network of long flexible chains. For X-NaOl=0.2 and 0.4 mixtures, both the shear storage modulus G' and the shear loss modulus G' showed weak dependences on angular frequency omega with a relation G'&gt;G'. From cryo-TEM observations, vesicles coexisted with threadlike micelles in mixtures of X-NaOl=0.2 and 0.3. As X-NaOl increased further (X-NaOl=0.5 and 0.6), threadlike micelles disappeared and the coexistence of vesicles and globular micelles was observed. At X-NaOl=0.5, the viscosity decreased remarkably, which was consistent with the disappearance of threadlike micelles. The results indicated that vesicles were formed by the addition of NaOl to OleylDMAO solutions, contrary to the expectation of a decrease of the packing parameter with the introduction of electric charges.

    DOI: 10.1007/s00396-004-1049-8

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  • Acid soap formation of oleic acid and catanionic complex formation in the alkyldimethylamine oxide/sodium oleate equimolar mixtures

    S Tanaka, H Kawasaki, H Maeda

    COLLOID AND POLYMER SCIENCE   282 ( 5 )   468 - 475   2004年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER-VERLAG  

    The influence of adding alkyldimethylamine oxide (CnDMAO) with varying alkyl chain lengths (n(c)) on the acid soap formation of oleic acid was investigated. The solutions of equimolar mixtures of CnDMAO and sodium oleate (Na(+)Ol(-)), each 25 mmol kg(-1), became turbid at a certain critical pH (pH(c)) on decreasing pH. Values of the pH(c) depended on n(c) and showed the minimum at C10DMAO/NaOl mixture. The presence of the minimum was interpreted in terms of two different kinds of the complex formed in the micelles depending on n(c): the catanionic complex (CnDMAOH(+)/Ol(-)) in the mixed micelles of n(c)=16, 14, 12 and 10, and the acid soap of oleic acid for C6DMAO/NaOl and C8DMAO/NaOl mixtures. At pH(c) where the amounts of these complexes of double-chain nature reached certain critical values in the mixed micelles, a phase separation (most probably lamella formation) took place. It was expected that the critical amount of the catanionic complex was smaller for the mixtures of higher n(c) values and hence pH(c) increased with n(c) for the mixtures n(c)greater than or equal to10. For the mixtures of n(c)&lt;10, it was expected that the amount of the acid soap in the mixed micelles increased with decreasing n(c) at a given pH and the pH(c) increased with decreasing n(c). Micelle compositions at cmc were evaluated on the basis of the regular solution theory coupled with the pseudo phase approximation. The micelle compositions at 100 mmol kg(-1) were examined with C-13-NMR. The results showed the mixed micelle formation for n(c)=16-10, while the micelles mostly consisting of oleic acid for the mixtures of n(c)=8 and 6. The assumption of two different complexes for the two groups of the mixture was thus supported. The cmc range of mixed micelles was evaluated and it was well correlated with the observed concentration range of pyrene fluorescence change.

    DOI: 10.1007/s00396-003-0970-6

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  • Structures and dynamics of dodecyldimethylamine oxide intercalated into RUB-18

    SI Ishimaru, M Togawa, E Shinohara, R Ikeda, H Kawasaki, H Maeda

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   65 ( 2-3 )   425 - 427   2004年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    A new proton-conducting intercalation system of a layered polysilicate compound, octosilicate (RUB-18), was synthesized by exchanging Na+ ion with half- and full-ionized dodecyldimethylamine oxides. RUB-18 intercalated by half-ionized dodecyldimethylamine oxide was shown to contain alkyl chains of the trans zigzag conformation by powder X-ray diffraction and C-13 CP-MAS NMR measurements. The DC electrical conductivity and the distribution factor beta of the relaxation time were determined to be 6.4 x 10(-6) S m(-1) and 0.67, respectively, from Cole-Cole plots of the complex impedance measured at room temperature under the relative humidity of 100%. (C) 2003 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.jpcs.2003.09.014

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  • Vesicle formation of tetradecyldimethylamine oxide in water with respect to the protonation by adding aromatic sulfonic acids 査読

    M Miyahara, R Imahayashi, H Kawasaki, H Maeda

    MESOPHASES, POLYMERS, AND PARTICLES   129   62 - 69   2004年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPRINGER-VERLAG BERLIN  

    The protonation effect of tetradecyldimethylamine oxide (Cl4DMAO) on the aggregate structures (a surfactant concentration, Ct = 2 x 10(-2) mol kg(-1)) in water at 25degreesC was examined by adding aromatic sulfonic acids of 2-naphtalenesulfonic acid (NphH). It turned out that partially protonated C14DMAO formed vesicles in the range of the degree of the protonation a from alpha = 0.25 to alpha = 0.5. The critical vesicle formation concentration (cvc) of the vesicle at alpha = 0.4 was suggested to be around Ctsimilar to3 x 10(-4) mol kg(-1), which was very close to the critical aggregation concentration (cacsimilar to8 x 10(-5) mol kg(-1)). The kinetics of the micelle-to-vesicle transition by changing pH was examined and it could be analyzed as a first-order process. The rate constant on the vesicle formation was found to increase linearly on both the temperature and the ionic strength of the solution. Contrary to the vesicle formation process, the vesicle breakdown process was too fast (&lt; 10 s) to follow in the measurable time scale. The leakage experiment of glucose from the vesicle was carried out with the vesicles. To examine effects of the hydrophobicity of the aromatic sulfonic acids on the aggregate structures, the aggregate structures were also examined for such as benzenesulfonic acid (BzH) and p-phenolsulfonic acid (PheH). In the case of the BzH, the interaction was much weaker than that of the NphH and the phase separation occurred by protonation. PheH was found to be almost ineffective to induce a significant structural change of the micelle, in spite of the hydrophobic nature of the aromatic counterion.

    DOI: 10.1007/b100303

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  • The effect of the porotonation of tetradecyldimethyl amineoxide on the aggregate structures in water by adding aromaticsulfonic acids 査読

    KAWASAKI Hideya, M. Miyahara, R. Imahayashi, H. Maeda

    Prog. Collid. Polym. Sci   ”129, 62-69”   2004年

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  • Rapid synthesis of gold nanorods by the combination of chemical reduction and photoirradiation processes; morphological changes depending on the growing processes

    Y Niidome, K Nishioka, H Kawasaki, S Yamada

    CHEMICAL COMMUNICATIONS   2367-2368 ( 18 )   2376 - 2377   2003年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    Combination of chemical reduction of tetrachloroaurate by ascorbic acid and subsequent ultraviolet photoirradiation resulted in the quick generation of gold nanorods quantitatively, with appreciable shape changes as the reaction proceeds.

    DOI: 10.1039/b307836a

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  • Vesicle-micelle transition and the stability of the vesicle dispersion in mixtures of tetradecyldimethylamine oxide hemihydrochloride and sodium naphthalenesulfonate

    H Kawasaki, R Imahayashi, S Tanaka, M Almgren, G Karlsson, H Maeda

    JOURNAL OF PHYSICAL CHEMISTRY B   107 ( 33 )   8661 - 8668   2003年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Spontaneous vesicle formation was found to occur on simple mixing of two solutions: a micellar solution of tetradecyldimethylamine oxide hemihydrochloride (C14DMAO.1/2HCl) and a sodium 2-naphthalenesulfonate (NaNphS) salt solution. The stability of the vesicle dispersion and the sign of the vesicle charge depended on the mixing mole ratio beta (=[NaNphS]/[C14DMAO.1/2HCl]) at 25 degreesC: elongated micelles (beta &lt; 0.25) --&gt; positively charged unilamellar vesicle dispersion (0.3 &lt; beta &lt; 0.5) --&gt; sediments consisting of aggregated multilamellar vesicles (0.55 &lt; beta &lt; 0.75) --&gt; negatively charged unilamellar vesicle dispersion (0.75 &lt; beta &lt; 5). The beta-dependent aggregation behavior of the vesicles correlated well with the change in the potential of the vesicles, and it was described by the normal DLVO theory. This indicates that the repulsive double-layer force is a major factor in stabilizing the vesicle dispersion, while the main driving force of the aggregation is an attractive van der Waals force between the vesicle bilayers. CryoTEM pictures demonstrated that the vesicles showed a drastic change in microstructure upon aggregation. In the aggregated multilamellar vesicles, the electrostatic repulsion between the bilayers is suppressed by the complete binding of counterions NphS(-), leading to the change from unilamellar vesicles to aggregated multilamellar vesicles. It is suggested that vesicle formation in the C14DMAO.1/2HCl-NaNphS system can be attributed to the combined effect of the hydrogen bonding between the cationic and the nonionic headgroups (-N+-OH...O-N-) and the strong counterion NphS- binding.

    DOI: 10.1021/jp0300804

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  • Hydrogen ion titration of oleic acid in aqueous media: further examinations on sodium and potassium oleate systems

    K Kaibara, T Ogawa, H Kawasaki, M Suzuki, H Maeda

    COLLOID AND POLYMER SCIENCE   281 ( 3 )   220 - 228   2003年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER-VERLAG  

    Hydrogen ion titration profiles of the aqueous potassium oleate/oleic acid systems were examined as a function of the degree of neutralization, beta, in corresponding metal chloride solutions. At temperatures higher than 5 degreesC, the titration curves were almost identical to those of sodium oleate systems at temperatures higher than 20 degreesC characterized by a single constant-pH region due to the multiple-phase equilibrium including metal oleate micelles. At a low temperature, 0 degreesC, on the other hand, different titration curves characterized by two constant-pH regions were observed. The ranges of beta of the high constant-pH region were 0.6 &lt; beta &lt; 0.95 in contrast to the sodium oleate system (0.5 &lt; beta &lt; 0.95). These results suggested that the acid soap compositions, oleate acid/metal oleate ratios, were 2:3 for the potassium oleate and 1: 1 for the sodium oleate systems. Differential scanning calorimetry analysis for the potassium oleate/oleic acid and the sodium oleate/oleic acid two-component systems detected the formation of an acid soap with equivalent compositions in aqueous media. To inspect further the changes in the temperature profiles of the titration curves, the temperature dependence of the solution properties of potassium and sodium oleates was examined.

    DOI: 10.1007/s00396-002-0753-5

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  • Effects of hydrophobic counterions on the phase behavior of tetradecyldimethylhydroxylammonium chloride in aqueous solutions

    H Kawasaki, R Imahayashi, H Maeda

    LANGMUIR   18 ( 22 )   8358 - 8363   2002年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We investigated the phase behavior of cationic tetradecyldimethylhydroxylammonium chloride (C14DMAOH(.)Cl) (a fixed surfactant concentration, 20 mM) in the presence of sodium 2-naphthalenesulfonate (SNphS) as a function of the molar ratios beta (= SNphS/C14DMAOH(.)Cl) by turbidity, viscosity, dye solubilization, and polarizing microscopy. The C14DMAOH(.)Cl/SNphS system formed aggregates with a lower curvature than cetyltrimethylammonium bromide (C16TAB)/aromatic counterion systems, despite the shorter alkyl chain. Addition of SNphS into the C14DMAOH(.)Cl solution at 25 C produced precipitates of solid crystals above beta similar to 0.5, in contrast with long fibrous micelles of many other cationic micellearomatic counterion pairs. The crystalline solids (tetradecyldimethylhydroxylammonium naphthalenesulfonate, C14DMAOH(.)NphS) at 20 mM concentration were transformed into the lamellar liquid crystalline phase dispersion (lamellar droplets) above 54 C. The lamellar phase was not spontaneously converted into vesicles upon dilution to 1 mM in contrast to spontaneous vesicle formation of cetyltrimethylanimonium hydroxynaphthalenecarboxylate (C16TAHNC). The stability of the lamellar droplets was rather limited in the low surfactant concentration of 1 mM. The phase separation into the lamellar liquid crystalline phase and the clear isotropic solution was observed within several hours. By gentle shaking by hand, on the other hand the lamellar phase could be dispersed to lamellar droplets at 60 degreesC again. The fact that the C14DMAOH(.)NphS prefers the planar bilayer structure (a precipitate or a lamellar liquid crystalline phase) to the curved bilayer structure (vesicles) may manifest the rigid surface of the bilayers. Compared with C16TAHNC, the rigid nature of the C14DMAOH(.)NphS bilayer is likely due to the proposed hydrogen bond formation between the two neighboring cationic headgroups, where their charge repulsion was now suppressed by the counterion binding. To examine effects of the hydrophobicity of the counterion on the phase behavior, similar experiments were carried out for sodium benzenesulfotiate (SBzS) and Na2SO4. In the case of the SBzS, the interaction was much weaker than that of SNphS and no lamellar droplets were observed at elevated temperatures. Na2SO4 was found to be ineffective to induce a structural change of the micelle, despite consisting of divalent counterions.

    DOI: 10.1021/la0205021

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  • The effect of the heterogeneity of N-isopropylacrylamide-co-styrene sulfonate gel on the binding behavior of an ionic surfactant with the gel

    H Katsuura, H Kawamura, M Manabe, H Kawasaki, H Maeda

    COLLOID AND POLYMER SCIENCE   280 ( 8 )   710 - 715   2002年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER-VERLAG  

    The effects of the heterogeneity of the gel on the swelling behavior and on the binding of surfactant counterions, dodecylpyridinium chloride (C12Py), were examined using copolymer gels of N-isopropylacrylamide and p-styrene sulfonate (pSS). The feed mole fractions of pSS, X, were 0.05, 0.1, 0.15, 0.20 and 0.25. The gels prepared at 40 +/- 2 degreesC were turbid, indicating heterogeneous monomer densities on a microscopic scale, while the gels prepared at 41 degreesC were transparent. Significantly different swelling behavior was observed on changing the temperature between the two kinds of gel: the change in gel volume in a given temperature interval was always smaller for the heterogeneous gels than for the homogeneous gels. The binding isotherms of C12Py were, in contrast, very similar between the two kinds of gel. The cooperative parameter of the binding, u, was rather small (2-4) for both types of gel. This small cooperativity was ascribed to relatively low charge densities. A small but significant decrease in u was found when X increased.

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  • Effects of protonation of alkyldimethylamine oxides on the dissolution temperature in aqueous media

    H Kawasaki, K Ookuma, H Maeda

    JOURNAL OF COLLOID AND INTERFACE SCIENCE   252 ( 2 )   419 - 425   2002年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACADEMIC PRESS INC ELSEVIER SCIENCE  

    The effects of protonation (ionization) of hexadecyldimethylamine oxides on the dissolution temperature in aqueous media were investigated by differential scanning calorimetry. Only one endothermic peak was reproducibly observed at all the degrees of ionization a examined that were assigned to the transition from the solid (the gel phase) to the solution containing micelles. The dissolution temperature versus alpha curves showed a maximum at alpha = 0.5, strongly suggesting the formation of a stable complex of 1-to-1 composition of the nonionic and cationic species through the proposed hydrogen bond. From the shape of the dissolution curve as well as the composition analysis of the solid phase, the solid solution was found to be formed over all alpha values. Effects of alkylchain length on the dissolution temperature for a homologous series of octadecyl- (C18DAO), hexadecyl- (C16DAO), and tetradecyldimethylamine oxide (C14DAO) were also examined for alpha = 0.5 and alpha = 1. Both the transition temperature and the associated thermodynamic quantities DeltaH and DeltaS increased systematically with the chain length, but for alpha = 0.5 smaller increases in DeltaH and DeltaS values with the chain length were observed [DeltaH/CH2 (kJ mol(-1)) = 7.2 +/- 0.2 and 2.2 +/- 0.5 for alpha = 1 and alpha = 0.5, respectively, and DeltaS/CH2 (J mol(-1) K-1) = 21.9 +/- 1.8 for alpha = 1 and 4.6 +/- 1.9 for alpha = 0.5]. By annealing procedures, the metastable nature of the gel phase was demonstrated for the C16DAO (alpha = 1) solid. (C) 2002 Elsevier Science (USA).

    DOI: 10.1006/jcis.2002.8458

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  • Reversible vesicle formation by changing pH

    H Kawasaki, M Souda, S Tanaka, N Nemoto, G Karlsson, M Almgren, H Maeda

    JOURNAL OF PHYSICAL CHEMISTRY B   106 ( 7 )   1524 - 1527   2002年2月

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    記述言語:英語   出版者・発行元:AMER CHEMICAL SOC  

    Protonation of oleyldimethylamine oxide (OleylDAO) decreased the average curvature and induced a change from threadlike micelles in the nonionic state to particles (vesicles) at the half-protonated state (degree of ionization alpha = 0.5), concluded from viscoelastic measurements and cryoTEM observations in water at 25 degreesC. The viscoelastic changes were confirmed to be reversible with respect to a pH change. The times required for the solutions to recover the behavior at alpha = 0.5 after the addition of HCl to the solutions of alpha = 0 were about 25 h at 0.05 mol (kg water)(-1) and 14 days at 0.15 mol (kg water)(-1). The correspondence between the viscoelastic properties and the cryoTEM observations was good. It was suggested from the viscoelastic properties that the threadlike micelles grew with alpha at alpha = 0.2, but the change from threadlike micelles to vesicles was suggested as alpha increased further. On increasing the concentration at alpha = 0.5, the vesicles became perforated, probably due to the increased counterion concentration. The present results indicate unambiguously the important and effective action of protonation in controlling the packing parameter, or the mean curvature, of amine oxide amphiphiles.

    DOI: 10.1021/jp013366m

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  • Binding of a surfactant counterion to low-charge-density poly(acrylic acid) and poly(methacrylic acid)

    H Katsuura, H Kawamura, M Manabe, H Kawasaki, H Maeda

    COLLOID AND POLYMER SCIENCE   280 ( 1 )   30 - 37   2002年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER-VERLAG  

    The binding of a cationic surfactant, dodecylpyridinium (C12Py) chloride, with a low-charge-density poly (methacrylic acid) (PMA) was investigated in buffer solutions under the condition of constant pH. The binding isotherms with PMA consisted of two and three steps at a pH lower and higher than 3.2, respectively. Bindings in the first step were independent of pH and this step was considered to correspond to the solubilization of the hydrocarbon chains of C12Py into the nonpolar region of the compact form of PMA. This is the indication of the compact form from the binding isotherm. At pH higher than 3.2, the second step was discriminated and it depended on the pH. In the third step, a sharp rise in the degree of binding (beta) was observed accompanying the solubilization of the precipitates of the PMA-C12Py complex. The binding with poly(acrylic acid) (PAA) and PMA in conventional unbuffered NaCl solutions was also examined and the pH profile of the solution during the binding process was determined. In the case of unbuffered NaCl solutions, the binding with PAA took place cooperatively at the critical association concentration (cac). The binding isotherm consisted of two steps and the pH decreased with the increase in beta. The binding isotherm of PMA, on the other hand, consisted of three steps: the pH decreased slightly in the first step and considerably in the second step with the increase in beta but it increased with beta in the third step, exhibiting a pH minimum around 3.2. The binding in the first step coincided with that obtained in the buffered solutions. Linear relationships between beta and the pH were found for both polymers. In the case of PMA, no cac was observed in both buffered and unbuffered NaCl solutions.

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  • Effects of protonation on the aggregate structures of tetradecyldimethylamine oxide at solid-solution interfaces

    H Kawasaki, M Syuto, H Maeda

    LANGMUIR   17 ( 26 )   8210 - 8216   2001年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We have investigated the effects of ionization on the aggregate structures of tetradecyldimethylamine oxide (C14DAO) at the mica-solution and graphite-solution interfaces by atomic force microscopy. It was found that the C14DAO forms aggregate structures with lower curvature at the mica-solution interface as the degree of ionization of C14DAO increased. Nonionic C14DAO formed short cylindrical aggregates on mica. On the other hand, a flat bilayer on mica was observed for the half-ionized C14DAO1/2HCl and the fully ionized C14DAOHCl. The flat bilayers for C14DAO1/2 HCl and C14DAOHCl suggest the higher packing parameter (or lower mean curvature) character of these surfactants, compared to the cationic quaternary ammonium surfactant with a single tetradecyl tail as well as the nonionic C14DAO which all form the cylindrical aggregates on mica. The reason for this lower curvature of half-ionized C14DAO was suggested to be the hydrogen bonds between the headgroups (i.e., the cationic-nonionic pair for C14DAO1/2 HCl), in addition to the contribution of the electrostatic attractive interaction between the cationic headgroup and the negatively charged mica. Contrary to the aggregates on mica, the dominant structures of C14DAO an graphite were hemicylinders, irrespective of the ionization. It seas found that the ionization increased the distances between the hemicylindrical aggregates due to the electrostatic repulsion between the aggregates rather than induced the change in the aggregate structure. The weak dependence of the ionization on the aggregate structures at the graphite-solution interface is suggested to be due to the dominant attractive interaction between the graphite surface and the surfactant tail.

    DOI: 10.1021/la010934g

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  • Effects of alkyl chain length on the solid state phase behaviors of alkyldimethylamine oxide hydrochlorides and hemihydrochlorides

    M Miyahara, H Kawasaki, T Fukuda, Y Ozaki, H Maeda

    COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS   183   475 - 485   2001年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Solid phase behaviors of alkyldimethylamine oxide hydrochlorides (CnDAO . HCl) and hemihydrochlorides (CnDAO .1/2HCl) were investigated by differential scanning calorimetry (DSC) and infrared spectroscopy on five members n=10, 12, 14, 16 and 18. Two main transitions were commonly detected by DSC on the protonated (cationic) species (CnDAO . HCl): the order-disorder transition of the hydrocarbon chain (or chain melting) and the melting to a liquid crystalline(LC) phase. Both the chain-melting transition temperature T-chain and the associated thermodynamic quantities DeltaH(chain) and DeltaS(chain) increased systematically with the chain length. Only one phase transition assigned to the partial chain melting was detected by DSC on the hemihydrochlorides (CnDAO .1/2HCl) except for n = 12. The associated enthalpy changes DeltaH(tr) were smaller than DeltaH(chain) of the corresponding hydrochlorides by about 10-15 kJ mol(-1). For the hydrochlorides, the high temperature solid phase (S2) was stable only for a limited temperature range. On the contrary, the S2 phase of hemihydrochlorides was stable over a considerable temperature range. This stable nature of the hemihydrochlorides suggested the attractive head group interaction inferred from the previous solution studies. (C) 2001 Elsevier Science B.V. All rights reserved.

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  • Effects of protonation on the viscoelastic properties of tetradecyldimethylamine oxide micelles

    H Maeda, A Yamamoto, M Souda, H Kawasaki, KS Hossain, N Nemoto, M Almgren

    JOURNAL OF PHYSICAL CHEMISTRY B   105 ( 23 )   5411 - 5418   2001年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Marked effects of protonation (ionization) of tetradecyldimethylamine oxide on the viscoelastic properties of the micelle solutions were found. The effect strongly suggests the short-range attractive interaction between the headgroups of the nonionic (deprotonated) and the cationic (protonated) species. The zero shear viscosity reached a maximum at the half-ionized state (the degree of ionization alpha = 0.5) and the value was larger than that of the nonionic species (alpha = 0) or the cationic species (alpha = 1) by more than 2 orders of magnitude. At a surfactant concentration C of 0.1 mol/kg, approximately single Maxwell behavior was observed as a approached 0.5 from either side. For the half-ionized micelles (alpha = 0.5) in 0.1 mol/kg NaCl solutions, the steady-state compliance J(e)(0) decreased with C with an exponent of 2.1 +/- 0.2, suggesting the presence of an entangled network of flexible threadlike micelles. The relaxation time, on the other hand, exhibited a nonlinear dependence on C. It was about 0.1 s and remained nearly constant in the range C &gt; 0.1 mol/kg (regime I), whereas it increased with C in the range of C &lt; 0.09 mol/kg (regime II) with an exponent slightly larger than 1. The single Maxwell behavior was observed in regime I. The regime shift was not controlled by the ratio C/m(s), m(s) representing the NaCl concentration. Effects of NaCl concentration and the temperature on the viscoelastic properties were also examined at alpha = 0.5. Cryo-transmission electron micrographs clearly showed a highly entangled network in the solution for alpha = 0.5, while much smaller micelles for alpha = 0. Contrary to the expectation from the theological results, a highly entangled network was also observed in the solution for alpha = 1.

    DOI: 10.1021/jp0101155

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  • FT-IR study on hydrogen bonds between the headgroups of dodecyldimethylamine oxide hemihydrochloride

    H Kawasaki, H Maeda

    LANGMUIR   17 ( 7 )   2278 - 2281   2001年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

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  • Salt-induced volume phase transition of poly(N-isopropylacrylamide) gel

    M Annaka, K Motokawa, S Sasaki, T Nakahira, H Kawasaki, H Maeda, Y Amo, Y Tominaga

    JOURNAL OF CHEMICAL PHYSICS   113 ( 14 )   5980 - 5985   2000年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    The salt effect on the phase transition of N-isopropylacrylamide (NIPA) gel was studied. The swelling behavior of the NIPA gel strongly depends on the salt concentration and is well described as a function of the chemical potential difference of water molecules in solution from that at the transition. From the analysis of the OH stretching, Raman spectra in water and in various aqueous solutions in terms of collective proton motions reveals that the presence of salts tends to disrupt or distort the water molecules in hydrophobic hydration shell around the NIPA gel. This leads to inducing the growth of the cluster shell around the salts, which leads to gel collapse. The volume phase transitions due to the different types of perturbation (temperature, salt) are induced by the same mechanism, hydrophobic hydration and dehydration, and therefore can be described in a unified manner in terms of the chemical potential and the collective proton motions of water molecules. (C) 2000 American Institute of Physics. [S0021-9606(00)52037-6].

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  • Solid state phase behaviors of dodecyldimethylamine oxide: protonation and counterion effects 査読

    H Kawasaki, T Fukuda, A Yamamoto, K Fukada, H Maeda

    COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS   169 ( 1-3 )   117 - 124   2000年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Solid phase behaviors of dodecyldimethylamine oxide (C12DAO) studied by differential scanning calorimetry and X-ray scattering have shown clearly the effects of protonation. Besides the protonated (cationic) (C12DAO HCl) and the nonionic (C12DAO) species, 1:1 composition or hemihydrochloride (C12DAO 1/2 HCl) was shown to be a stable complex. The phase behavior of C12DAOHCl was similar to that of dodecylammonium chloride rather than dodecyltrimethylammonium chloride (C12TACl), although similar crystal structure was suggested for C12DAOCl and C12TABr. Solid phase behaviors changed dramatically by changing the counterion from Cl- to NO3- or SO42- for both the cationic and 1:1 species. (C) 2000 Elsevier Science B.V. All rights reserved.

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  • Scattering from polymerlike micelles of TDAO in salt/water solutions at semidilute concentrations 査読

    V. M. Garamus, Jan Skov Pedersen, Hideya Kawasaki, Hiroshi Maeda

    Langmuir   16 ( 16 )   6431 - 6437   2000年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACS  

    Aqueous solutions of half-ionized tetradecyldimethylamine oxide (TDAO) with 0.1 M NaCl and varying surfactant concentration were studied by small-angle neutron scattering. The scattering data demonstrate the presence of wormlike micelles, and an analysis based on polymer theory and the results from Monte Carlo simulations was performed. The surfactant concentrations correspond to dilute and semidilute solutions for the wormlike micelles. The analysis of the forward scattering demonstrates a concentration dependence of the growth of the micelles in agreement with mean-field theory. The scattering data in the full range of measured scattering vectors were analyzed using a modified random phase approximation expression, and excellent agreement was found for concentrations up to 65 times the overlap concentration. The model fitting showed that the micelles have an elliptical cross section with semiaxes of about 16 and 28 angstroms. Based on the self-consistent analysis, an independent comparison between the correlation length determined from the scattering data and from Monte Carlo simulations was performed as a function of the reduced concentration.

    DOI: 10.1021/la000085h

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  • A bilayer formed by soluble amphiphiles with single chain at the mica-solution interface

    H Kawasaki, M Syuto, H Maeda

    CHEMISTRY LETTERS   972-973 ( 8 )   972 - 973   2000年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHEMICAL SOC JAPAN  

    We investigated the aggregate morphologies of tetradecyl-dimethylamine oxide hemihydrochloride (C14DAO . 1/2HCl) on mica surface in the surfactant solutions by Atomic Force Microscopy (AFM). C14DAO . 1/2HCl forms a flat bilayer on mice. This morphology is different from spheres or cylinders which have been reported for other cationic surfactants with a single tetradecyl tail. The reason for this lower curvature of the C14DAO . 1/2HCl aggregate on mica is discussed in terms of the hydrogen bond between the headgroups.

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  • Effect of the introduced charge on the thermal behavior of N-isopropylacrylamide gels in water and NaCl solutions

    H Kawasaki, S Sasaki, H Maeda, K Nishinari

    LANGMUIR   16 ( 7 )   3195 - 3199   2000年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Effects of the introduced charge on the thermal behavior of N-isopropylacrylamide (NIPA) gel were investigated by differential scanning calorimetry (DSC) for copolymer gels of NIPA and sodium styrenesulfonate (NIPA-SSNa) with various charge densities of the chains and ionic strengthes. As the SSNa contents of the NIPA-SSNa gel increased, the sharp endothermic peak of the NIPA gel in water changed into a broad one and the excess enthalpy change per mole of NIPA monomer (Delta H) decreased. The Delta H value is most likely related to the amount of the dehydration of NIPA chains. In NaCl solutions, however, the sharp endothermic peak was observed again for the NIPA-SSNa gel and the Delta H value was similar to that of the NIPA gel. We found that the DSC curve was very similar to the derivative profile of the swelling curve with respect to temperature both in water and in NaCl solutions. The good correspondence between the derivative curve and the DSC curve suggests that the volume shrinkage of the gel and the specific heat change of the gel are closely related. This similarity most probably originates from the fact that the temperature-induced volume shrinkage of the gel is caused by the dehydration of NIPA chains. On the basis of this correlation, the effect of the introduced charge on the DSC curve (i.e., the shape of the endothermic peak and the Delta H value) is explained in terms of the Donnan osmotic pressure of counterions.

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  • Partition of salts between N-isopropylacrylamide gels and aqueous solutions

    H Kawasaki, T Mitou, S Sasaki, H Maeda

    LANGMUIR   16 ( 3 )   1444 - 1446   2000年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

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  • Kinetic effects of the gel size on the thermal behavior of poly (N-isopropylacrylamide) gels: a calorimetric study

    H Kawasaki, S Sasaki, H Maeda

    HYDROCOLLOIDS, PT 1   65-70   65 - 70   2000年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    Effects of the gel size on the thermal behavior and the shrinking profile of chemically cross-linked poly( N-isopropylacrylamide)( NIPA)gel in water were mainly investigated by differential scanning calorimetry( DSC) and the volume measurement at the same heating rate as the DSC. The DSC thermogram of NIPA gel depended on the shrinking process at the transition. The DSC thermogram of NIPA gel of the smallest size ( 0.3 mm diameter at the preparation) gave double endothermic peaks and the gel underwent a discontinuous volume shrinkage ( i.e. a volume transition) at about 34.5 degrees C within the time scale of DSC run of heating rate of 0.1 degrees C/min. This suggests that the two-step cooperative dehydration of NIPA chains takes places in the volume shrinkage. It was proposed that the peak at the low temperature( peak 1) originated from the dehydration of NIPA chains without the volume transition while the peak at the high temperature ( peak 2) was associated with the discontinuous volume shrinkage. A single broad endothermic peak was observed for NIPA gel of the largest size (3 mm diameter at the preparation) that shrank only slightly during DSC run. For the largest gel, the volume transition cann0 ot occur within the time scale of DSC run due to the slow volume shrinkage while dehydration of the polymer chains takes place locally. The peak of the largest gel and the peak 1 were suggested to be due to the dehydration of NIPA chains coupled with the spinodal decomposition without the volume transition.

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  • Effects of protonation and the counterion species on the solid state phase behaviors of dodecyldimethylamine oxide 査読

    KAWASAKI Hideya, T.Fukuda, A.Yamamoto, K.Fukada, H.Maeda

    Colloid and Surface A   ”169, 117-124”   2000年

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  • Scattering from polymer-like micelles of Tetradecyldimethylamine oxide in salt/water solutions 査読

    KAWASAKI Hideya, ”V. M. Garamus, J. S. Pedersen, H. Maeda

    Langmuir   ”16(16), 6431-6437”   2000年

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  • Thermal properties of the ionized thermosensitive gels: A differential scanning calorimetric study 査読

    H Kawasaki, S Sasaki, H Maeda

    STATISTICAL PHYSICS   519   196 - 198   2000年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

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  • Effect of electric charges on the volume phase transition of thermosensitive gels

    H Maeda, H Kawasaki, S Sasaki

    HYDROCOLLOIDS, PT 1   35-44   35 - 44   2000年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    Effects of the introduced electric charges on the swelling behavior of a thermosensitive gel, N-isopropylacrylamide (NIPA), were examined with the copolymer gels with sodium acrylate(NaA) or sodium styrene sulfonate (NaSS). The introduced charge altered the volume change behavior of NIPA gels from the discontinuous type (the volume phase transition) to the continuous one by a very small amount, less than 0.01 mole fraction. This charge effect was suppressed by the addition of a salt, NaCl, and at the NaCl concentration of about 0.3 M or higher, the transition behavior was resumed. These effects of the charge and the salt were both understood in a unified manner in terms of the Donnan osmotic pressure of the shrunken state of the gels. In parallel with the change of the swelling behavior, the endothermic peak observed at the transition temperature of NIPA gels in the DSC measurements became smaller and broader as the mole fraction of the charged monomer increased. The solution nature of the shrunken state of NIPA gels was suggested from the effects of sugars and/or salts on the volume phase transition. This solution nature was suggested to be kept in the shrunken state of ionized NIPA gels. This is the prerequisite to the above interpretation of the charge effect in terms of the Donnan osmotic pressure of the shrunken state. Temperature-induced volume changes of the copolymer gels of NIPA with sodium acrylate were examined at various pH. The volume change of the gel was discontinuous against temperature at pH below 6.3, although it was continuous at pH above 7.5. Potentiometric titrations of the linear copolymer of NIPA and acrylic acid ( PNIPA-AA ) revealed that the dissociation constant of carboxyl groups in solutions decreased with raising temperature above 34 degrees C. The similar decrease in the carboxyl ionization with raising temperature was also observed for NIPA-AA gel. The resumed discontinuous volume change at neutral or acidic pH was correlated with the two effects arising from the protonation of the carboxylate groups of NIPA-AA gel :the reduced Donnan osmotic pressure and the presence of a significant fraction of unionized carboxyl groups in the gel at the collapsed state. The nature of the shrunken state under these pH values was suggested to differ considerably from that of NIPA or ionized NIPA gels. It is not solution-like but a space of low dielectric constant similar to the interior of globular proteins.

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  • Effect of donnan osmotic pressure on the volume phase transition of N-isopropylacrylamide gels

    S Sasaki, H Kawasaki, H Maeda

    LANGMUIR   15 ( 12 )   4266 - 4269   1999年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    The theory for describing the effect of Donnan osmotic pressure on the volume phase transition of NIPA gel is developed. The theory can well explain the experimental result that a continuous volume change behavior of charged NIPA gel in a salt-free solution turns to a discontinuous one in 0.1 M salt solution.

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  • Effects of acid strength of solid catalyst on cooling rate of a chemical heat pump with paraldehyde depolymerization 査読

    T Watanabe, H Kawasaki

    KAGAKU KOGAKU RONBUNSHU   24 ( 6 )   874 - 880   1998年11月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SOC CHEMICAL ENG JAPAN  

    The paraldehyde chemical heat pump is combined with a chemical reaction and a vapor-compression heat pump. The paraldehyde chemical heat pump generates cold thermal energy with depolymerization of paraldehyde (2,4,6-trimethyl-trioxane). The cooling rate of the paraldehyde chemical heat pump depends on the catalyst activity of the paraldehyde depolymerization. This study investigates the effect of the acid strength of the solid catalyst on the paraldehyde depolymerization rate, the cooling rate, and the coefficient of performance of the heat pump. The acid strength distribution of Amberlyst 15 E was measured for estimation of the catalyst activity of the paraldehyde depolymerization. The depolymerization rate was measured with Amberlyst 15 E of modified acid strength distribution. The high activity range of the acid strength is -7.1 &lt; pKa &lt; -4.3 for the paraldehyde depolymerization with Amberlyst 15 E. The coefficient of performance, the cooling rate and the catalyst weight were estimated with the acid strength. The weight of the catalyst can be reduced to 0.05 g with 1.6 g.s(-1) of the flow rate in the system when the cooling rate and COP are 0.9 kW and 6, respectively.

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  • Effects of the gel size on the volume phase transition of poly(N-isopropylacrylamide) gels: A calorimetric study

    H Kawasaki, S Sasaki, H Maeda

    LANGMUIR   14 ( 4 )   773 - 776   1998年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Effects of the gel size on the thermal behavior and the shrinking profile of a chemically cross-linked poly(N-isopropylacrylamide) (NIPA) gel in water were investigated by differential scanning calorimetry (DSC) and the volume measurement at the same heating rate as used for the DSC. The DSC thermogram of NIPA gel depended on the shrinking process at the transition. The DSC thermogram of the NIPA gel of the smallest size (0.3-mm diameter at the preparation) gave double endothermic peaks, and the gel underwent a discontinuous volume shrinkage (i.e. a volume transition) at about 34.5 degrees C in the DSC run with a heating rate of 0.1 degrees C/min. This suggests that the two-step cooperative dehydration of NIPA chains takes places in the volume shrinkage. It was proposed that the peak at the low temperature (peak 1) originated from the dehydration of NIPA chains without the volume transition while the peak at the high temperature (peak 2) was associated with the discontinuous volume shrinkage. A single broad endothermic peak was observed for the NIPA gel of the largest size (3-mm diameter at the preparation) that shrank only slightly during the DSC run. For the largest gel, the volume transition cannot occur within the time scale of the DSC run due to the slow volume shrinkage while dehydration of the polymer chains takes place locally. The peak of the largest gel and peak 1 were suggested to be due to the dehydration of NIPA chains coupled with the spinodal decomposition without the volume transition.

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  • Effect of pH on the volume phase transition of copolymer gels of N-isopropylacrylamide and sodium acrylate

    H Kawasaki, S Sasaki, H Maeda

    JOURNAL OF PHYSICAL CHEMISTRY B   101 ( 26 )   5089 - 5093   1997年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    A temperature-induced volume change of ionic gels was investigated for cross-linked copolymer gels of N-isopropylacrylamide and sodium acrylate (NIPA-AA) at various pH values, The volume change of the gel against temperature was discontinuous below pH 6.3, but it was continuous above pH 7.5. The continuous volume change observed for the completely ionized NIPA-AA gel suggests that an increase in the counterion osmotic pressure alters the discontinuous volume change of NIPA gel to the continuous one. Potentiometric titrations revealed that the dissociation constant of carboxyl groups of the linear copolymer of N-isopropylacrylamide and acrylic acid in solution decreased with increased temperature above 34 degrees C. The similar decrease in the carboxyl ionization with increasing temperature was also observed for NIPA-AA gel. The discontinuous volume change was correlated with the two effects arising from the decrease in the carboxyl ionization of NIPA-AA gel: the reduced Donnan osmotic pressure and the presence of a significant fraction of un-ionized carboxyl groups in the gel at the collapsed state.

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  • Effect of introduced electric charge on the volume phase transition of N-isopropylacrylamide gels

    H Kawasaki, S Sasaki, H Maeda

    JOURNAL OF PHYSICAL CHEMISTRY B   101 ( 21 )   4184 - 4187   1997年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We report the temperature-induced volume phase transition behavior of a copolymer gel of N-isopropylacrylamide and sodium acrylate (NIPA-AA) at pH 9.5 in the range of low mole fraction of the acrylate x (x &lt; 0.01), either in salt-free aqueous solution or NaCl aqueous solutions. Introduction of electric charges into the network switched the temperature-induced volume change of the gel from a discontinuous to a continuous type in salt-free aqueous solutions. The switching of the regime took place within a very narrow range of x around a very small value of 0.002. The continuous volume change in salt-free aqueous solution was transformed into the discontinuous one in NaCl aqueous solutions of 0.1 and 0.3 M. Effects of the two factors, the charged monomer fraction and the ionic strength, were explained in a unified manner in terms of the Donnan osmotic pressure. We found that the continuous or the discontinuous regime of NIPA-AA gel was well characterized, respectively, by the high or low osmotic pressure. Similar results were obtained with NIPA-sodium poly(styrene sulfonate) copolymer gels.

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  • Volume phase transition behavior of N-isopropylacrylamide gels as a function of the chemical potential of water molecules

    S Sasaki, H Kawasaki, H Maeda

    MACROMOLECULES   30 ( 6 )   1847 - 1848   1997年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

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  • Effects of the gel size on the thermal behavior of N-isopropylacrylamide gels in relation to the volume phase transition

    H Kawasaki, S Sasaki, H Maeda

    CHEMISTRY LETTERS   ”8, 723-724” ( 8 )   723 - 724   1997年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHEMICAL SOC JAPAN  

    Effects of the gel size on the thermal behavior and the shrinking profile of poly(N-isopropylacrylamide)(NIPA)gel in water were investigated by differential scanning calorimetry(DSC) and the volume measurement at the same heating rate. The DSC thermogram of NIPA gel of the smallest size gave double endothermic peaks and the gel underwent a discontinuous volume phase transition during DSC run. On the other hand, a single endothermic peak was observed for NIPA gel of the largest size and the gel shrank only slightly during DSC run due to the slow volume change.

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  • Saccharide-induced volume phase transition of poly(N-isopropylacrylamide) gels

    H Kawasaki, S Sasaki, H Maeda, S Mihara, M Tokita, T Komai

    JOURNAL OF PHYSICAL CHEMISTRY   100 ( 40 )   16282 - 16284   1996年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Saccharide-induced volume phase transition of poly(N-isopropylacrylamide) (NIPA) gels was found fur glucose, galactose, and sucrose, and the transition concentrations were about 1.5, 1.3, and 1.2 M, respectively. Temperature-induced volume phase transition of NIPA gels was affected by these saccharide, and the transition temperature decreased with increasing concentration of the saccharides. The reduced extent of the transition temperature increased linearly with the decrement of the chemical potential of water molecules due to the saccharides. This indicates that the change of the chemical potential of water induced by the addition of the saccharide plays an essential role in the saccharide-induced volume phase transition of NIPA gels.

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  • Surface tension of the polymer network of a gel

    T Nakamura, M Hattori, H Kawasaki, K Miyamoto, M Tokita, T Komai

    PHYSICAL REVIEW E   54 ( 2 )   1663 - 1668   1996年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    The surface tension of poly(N-isopropylacrylamide) gel is measured as a function of temperature. It is found that the surface tension of the gel suddenly decreases as the gel undergoes the discontinuous volume phase transition. The surface tensions of the polymer network of the gel are evaluated on the basis of a simple theory. The results yield that the surface tension of the poly(N-isopropylacrylamide) gel is mainly determined by the area occupied by the polymer chain on the surface of the gel in most of the temperature regions. In addition, it is also found that the surface tension of the polymer network of the gel shows a singular behavior in the immediate vicinity of the volume phase transition temperature of the gel.

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  • MULTIPLE VOLUME PHASE-TRANSITION OF NONIONIC THERMOSENSITIVE GEL

    H KAWASAKI, T NAKAMURA, K MIYAMOTO, M TOKITA, T KOMAI

    JOURNAL OF CHEMICAL PHYSICS   103 ( 14 )   6241 - 6247   1995年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    The volume phase transition is studied in the ternary system of the nonionic poly (N-normalpropylacrylamide) gel, water, and various alcohol. The gel shows a reentrant volume phase transition in all mixed solvent systems studied here. It is found that the phase transition is multiple in the mixed solvent systems of water-1-propanol and water-2-propanol. These results are discussed by the mean field theory in which the effects of the chain stiffening due to the adsorption of the solvent molecules are taken into account. These results strongly suggest that the adsorption and/or the desorption of the solvent molecules promote the multiple phase transition of the nonionic poly (N-normalpropylacrylamide) gel. (C) 1995 American Institute of Physics.

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    石田 尚之, 小林 幹佳, 武田 真一, 藤井 秀司, 米澤 徹, 中村 浩, 高江 恭平, 高橋かより, 日出間るり, 山中 淳平( 担当: 共著)

    「化学と工業」誌 日本化学会  2022年2月 

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  • Nanocomposite of Nanocellulose with Metal Nanoparticles for Printable and Flexible Electronics 査読

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  • Copper-Based Conductive Inks

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  • Nanocellulose Based Flexible Energy Storage Devices 査読

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  • 金属ナノ粒子の合成/構造制御とペースト化および最新応用展開

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  • 分散凝集の学理構築への科学と技術戦略

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  • 金属ナノ・マイクロ粒子の形状・構造制御技術

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  • 表面支援レーザー脱離イオン化質量分析法(SALDI-MS)のためのナノ粒子・ナノ構造表面設計

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  • HOPG/溶液界面での半円筒型ミセルを反応場として生成する白金ナノ構造体

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  • 界面活性剤評価・試験法 査読

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  • 高分子電解質ゲルの膨潤挙動 査読

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▼全件表示

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  • 合金クラスター/ローズベンガル含有キトサンナノゲルの抗菌性評価

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    日本バイオマテリアル学会大会予稿集   37th   183 - 183   2015年11月

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    記述言語:日本語   出版者・発行元:関西大学先端科学技術推進機構  

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  • 有機フッ素化合物の生分解試験と質量分析による分解物生成物の評価

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  • マイクロウェーブポリオール法による約2nmサイズの銅ナノ粒子の合成

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  • 電気エネルギー高効率利用社会を実現する新材料技術の開拓

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  • タンパク質保護金ナノクラスターの溶液合成 (特集 プロジェクト研究報告概要集) -- (先端科学技術推進機構研究グループ)

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  • 質量分析法を用いたLFプラズマジェット由来の大気イオン種の生成・反応機構

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    応用物理学会学術講演会講演予稿集(CD-ROM)   72nd   2011年

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  • LFプラズマジェットにより生成される大気イオン種の質量分析

    北村豪, 川崎英也, 荒川隆一, 北野勝久

    応用物理学関係連合講演会講演予稿集(CD-ROM)   58th   2011年

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  • ESIに近い大気圧マトリックス支援レーザー脱離イオン化(AP-MALDI)の特性

    高岡真也, 川崎英也, 木内正人, 荒川隆一

    質量分析総合討論会講演要旨集   59th   2011年

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  • LC/MSによる前躯体および中間代謝体を含む有機フッ素化合物の一斉分析法の検討

    矢本善也, 竹峰秀祐, 松村千里, 鈴木元治, 川崎英也, 中野武, 荒川隆一

    環境化学討論会要旨集(CD-ROM)   20th   2011年

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  • LC-APCI-MSによる前躯体および中間代謝体を含む有機フッ素化合物の一斉分析

    矢本善也, 竹峰秀祐, 松村千里, 鈴木元治, 川崎英也, 中野武, 荒川隆一

    質量分析総合討論会講演要旨集   59th   2011年

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  • Au<sub>25</sub>超クラスターの高次バンドの吸収による励起発光スペクトル

    坂永勇, 松末和憲, 稲田貢, 齊藤正, 川崎英也, 岩崎泰彦, 梅津郁朗, 杉村陽

    応用物理学会学術講演会講演予稿集(CD-ROM)   71st   ROMBUNNO.14A-NC-12   2010年8月

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    記述言語:日本語  

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  • 機器分析による壁画中の有機及び無機化合物検出の試み

    浅井 重博, 久富 広隆, 川崎 英也, アフメド シュエイブ, 荒川 隆一

    Semawy menu   1   93 - 101   2010年3月

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    記述言語:日本語   出版者・発行元:関西大学文化財保存修復研究拠点  

    Organic binding media and color materials used in Egyptian wall paintings were characterized using gas chromatograph-mass spectrometry (GC-MS). Fourier-transform infrared spectroscopy (FT-IR) and Raman spectroscopy. The small samples of the wall paintings were obtained from the debris in Funeral House (Egyptian House) in Tuna el-Gabal that was at the age of Persian or Ptolmaic Period. The aim of this study is to investigate a possibility of discrimination between Arabic gum and animal protein-based binders used in ancient Egypt and to recognize the use of mixtures of the two products. The GC-MS results showed that saturated fatty acid esters and the compound which seemed to be fatty acid glyceride were detected in the extract of the wall surface. Unsaturated aliphatic alcohols, esters, and the components with a steroid frame were observed from the direct probe method of EI-MS. In FT-IR, the absorption bands of calcium hydroxide in the red part of the painting and inorganic oxide in the black part were observed. In Raman spectra, it was supposed that amorphous carbon was used for color material of the black district and cinnabar (HgS) was for that of the red part. In addition, the color materials with fluorescence were detected in the red and blue part of surface.

    CiNii Books

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  • 低周波大気圧マイクロプラズマジェットによる大気イオン種の質量分析

    北村豪, 幣小百合, 川崎英也, 北野勝久, 荒川隆一

    質量分析総合討論会講演要旨集   58th   2010年

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  • 水試料中のフッ素テロマー化合物の分析法の検討

    竹峰秀祐, 矢本善也, 奥野俊博, 種田あずさ, 松村千里, 鈴木元治, 鶴川正寛, 英保次郎, 川崎英也, 中野武, 荒川隆一

    日本水環境学会シンポジウム講演集   13th   2010年

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  • DMF還元法により作製されたAuクラスターの光学特性

    松末和憲, 田井浩平, 稲田貢, 川崎英也, 岩崎泰彦, 齊藤正, 梅津郁朗, 杉村陽

    応用物理学会学術講演会講演予稿集   70th ( 2 )   810   2009年9月

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    記述言語:日本語  

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  • 試料捕捉合金、質量分析装置、質量分析方法、試料捕捉方法、試料捕捉合金、試料捕捉合金製造方法 (2009-171507)

    川崎 英也, 樽井 彰, 渡辺 健宏, 荒川 隆一

    2009年7月

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  • 質量分析用基板及びその製造方法並びに質量分析法(2009-163318)

    川崎 英也, 荒川 隆一, 溝口 大剛, 室内 聖人, 田村 祐介

    2009年7月

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  • ナノ粒子蛍光体の製造方法(特願2009-154932)

    川崎 英也, 岩﨑 泰彦, 柴田 靖久

    2009年6月

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  • 金ナノ粒子積層基板を利用したソフトレーザー脱離イオン化質量分析法の開発

    川崎 英也, 荒川 隆一

    レーザ加工学会誌   16 ( 1 )   38 - 41   2009年3月

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    記述言語:日本語   出版者・発行元:高温学会レーザ加工学会  

    CiNii Books

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  • 表面支援レーザー脱離イオン化質量分析法(SALDI-MS)のためのナノ粒子・ナノ構造表面設計

    川崎 英也, 渡辺 健宏, 荒川 隆一

    コロイドアンドインターフェースコミュニケーション   34 ( 1 )   14 - 16   2009年3月

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    記述言語:日本語   出版者・発行元:日本化学会コロイドおよび界面化学部会  

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  • 質量分析用基板及びその製造方法並びに質量分析法(2008-332164)

    川崎 英也, 渡辺 健宏, 荒川 隆一, 溝口 大剛, 室内 聖人, 田村 祐介

    2008年12月

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  • ソフトイオン化法が革新を導いた質量分析技術 (特集 化学のブレークスルーを支える「革新機器」) -- (化学を躍進させた革新機器の最前線)

    川崎 英也, 荒川 隆一

    化学   63 ( 10 )   18 - 21   2008年10月

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    記述言語:日本語   出版者・発行元:化学同人  

    CiNii Books

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  • ナノ構造を利用した表面支援レーザー脱離イオン化質量分析法

    荒川 隆一, 川崎 英也

    ぶんせき   ( 401 )   230 - 235   2008年5月

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    記述言語:日本語   出版者・発行元:日本分析化学会  

    CiNii Books

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  • 金属ナノ粒子を利用するLDI-MS

    米澤徹, 川崎英也, 樽井章, 渡辺健宏, 荒川隆一, 島田敏宏, 真船文隆

    高分子学会予稿集(CD-ROM)   57 ( 1 Disk1 )   2008年

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  • 高分子化合物の分析方法(特願2007-277230)

    川崎 英也

    2007年

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  • MALDI質量分析測定のためのナノ粒子担持イオン化基板の製造方法とその用途(特願2007- 36658)

    川崎 英也

    2007年

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  • 固液界面への界面活性剤の吸着とナノ自己集合体形成

    川崎 英也

    工学と技術 : 関西大学工学会誌   13 ( 4 )   49 - 54   2006年11月

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    記述言語:日本語   出版者・発行元:関西大学  

    CiNii Books

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  • “固/液界面ナノ構造集合体を反応場として形成される単結晶質白金ナノシート”

    川崎 英也, 魚田将史, 吉村巧己, 藤川大輔, 酒井剛, 木島剛

    2005年5月

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  • 「固/液界面に形成された吸着ミセル膜を反応場として形成される単結晶質の貴金属超薄膜ナノ粒子及びその製造法」(特願2005-057159)

    川崎 英也, 木島剛

    2005年3月

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  • “DDAB/水系におけるミセルーベシクル移転の対イオン結合度に及ぼす効果”

    川崎 英也, 小野陽介, 前田悠, 安中雅彦

    2004年9月

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  • 「金属微粒子の製造方法とその含有組成物」(特願2004-116254)

    川崎 英也, 溝口大剛, 永井昌憲, 室内聖人, 新留康郎, 西岡宏司, 山田淳

    2004年4月

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  • “温度変化によって誘起されるベシクルの可逆分散・凝集”

    川崎 英也, 宮原雅彦, マッツ アルムグレン, 前田悠

    2004年3月

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  • 「金ナノロッドの製造方法と用途」(特願2004-024006)

    川崎 英也, 新留康郎, 西岡宏司, 山田淳

    2004年1月

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  • 「金ナノロッドの調製法」(特願2003-31420)

    川崎 英也, 新留康郎, 西岡宏司, 山田淳

    2003年9月

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  • “固液界面における半円筒様ミセル形成とグラファイト粒子の分散安定性との相関”

    川崎 英也, 伴和哉, 前田悠

    2003年9月

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  • 「金ナノロッドの製造方法」(特願2003-208691)

    川崎 英也, 平田寛樹, 高田佳明, 李成圭, 溝口大剛, 石原眞興, 室内聖人

    2003年8月

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  • 「金ナノロッドの調製法」(特願2003-135062)

    川崎 英也, 新留康郎, 西岡宏司, 山田淳

    2003年5月

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  • Side-reactions in chemical heat pump system with paraldehyde depolymerization

    T Watanabe, H Kawasaki

    KAGAKU KOGAKU RONBUNSHU   25 ( 4 )   672 - 675   1999年7月

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    記述言語:日本語   掲載種別:速報,短報,研究ノート等(学術雑誌)   出版者・発行元:SOC CHEMICAL ENG JAPAN  

    The paraldehyde chemical heat pump generates cold thermal energy with depolymerization of paraldehyde (2,4,6-trimethyl-trioxane). This study investigates the by-products in the heat pump system. Crotonaldehyde (2-butenal) and the polymer of crotonaldehyde are main by-products. The proposed heat pump system has the solution cycle for the by-product. The cooling rate and the coefficient of performance of the proposed system decreases with a decrease in the amount of cyclic solution.

    Web of Science

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  • N-イソプロピルアクリルアミドゲルの体積相転移挙動と水の化学ポテンシャルとの相関

    川崎英也, 佐々木茂男, 前田悠, 三原諭, 中村崇人, 宮本啓一, 鴇田昌之, 駒井喬

    溶液化学シンポジウム講演要旨集   19th   1996年

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講演・口頭発表等

  • 機能性ナノ粒子を用いたレーザー脱離イオン化法

    川崎英也

    質量分析オープンイノベーション協働ユニットキックオフシンポジウム・蛋白研セミナー  2018年3月 

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  • 低温焼成型銅ナノインク調製に向けた銅ナノ粒子の設計~粒子界面からのアプローチ~

    川崎英也

    粉体工学会「ソフト粒子・界面研究会」・日本化学会新領域研究グループ「分散凝集の学理構築への科学と技術戦略」合同セミナー  2018年3月 

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  • 低温焼結型の銅微粒子・ナノ粒子・の設計 ~粒子界面からのアプローチ~

    川崎英也

    2017年度 第3回関西接着ワークショップ  2017年12月 

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  • Water-Soluble Gold Nanoclusters for Biomedical Applications: Fluorescence, Photodynamic Therapy, and Biomarker Sensing

    Hideya Kawasaki, Ryuichi Arakaw

    BIT’s 7th Annual World Congress of Nano Science & Technology-2017  2017年10月 

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  • 金属ナノクラスターの溶液合成とバイオ・医療応用

    川崎英也

    平成29年度 九州コロイドコロキウム  2017年9月 

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  • 銅系インクの低温焼成によるセルロース紙上での銅膜形成

    櫻井慎太郎, 川崎英也

    第66回高分子討論会  2017年9月 

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  • リグニンを炭素原料とする蛍光性カーボン量子ドットの水熱合成

    三木 恵太, 川崎 英也

    第66回高分子討論会  2017年9月 

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  • Design and Synthesis of Fluorescent Probe for Efficient Lipase Detection Based on TokyoGreen Platform

    M. Miwa, Y. Watanabe, M. Shizuma, H. Kawasaki, H. Sato

    2nd Asian Conference on Oleo Science  2017年9月 

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  • カーボンドットを還元剤とする金/銀ナノ粒子合成とその可視光応答型光触媒特性

    野崎孝至, 川崎英也

    第68回コロイドおよび界面化学討論会  2017年9月 

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  • 大気下低温焼成で高分子フィルム上に導電性銅膜を与えるコンポジット銅系インクの調製

    梶本栄一, 川崎英也

    第68回コロイドおよび界面化学討論会  2017年9月 

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  • リグニンを炭素原料とする蛍光性カーボン量子ドットの水熱合成

    三木 恵太, 川崎 英也

    第68回コロイドおよび界面化学討論会  2017年9月 

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  • カチオン性界面活性剤/アニオン性銀クラスターによるイオンコンプレックス形成と抗菌性樹脂への応用

    富永千明, 川﨑 英也

    第68回コロイドおよび界面化学討論会  2017年9月 

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  • Au/Ag合金クラスター含有キトサンナノゲルの光触媒特性

    彦惣 大輝, 川﨑 英也

    第68回コロイドおよび界面化学討論会  2017年9月 

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  • PEG修飾金ナノロッド表面からのヘキサデシルトリメチルアンモニウムブロミド除去の検討

    西田圭佑, 川﨑 英也

    第68回コロイドおよび界面化学討論会  2017年9月 

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  • 低温焼結性銅ペーストから得られる銅膜の耐久性を向上させる有機配位子酸化生成物寄与

    秋山侑介, 杉山知徳, 川崎英也

    第68回コロイドおよび界面化学討論会  2017年9月 

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  • 金属系シングルナノ粒子の分散と安定化

    川崎英也

    第68回コロイドおよび界面化学討論会  2017年9月 

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  • ペーパーエレクトロニクス用途向けの低温焼成タイプの導電性銅系ペーストの開発

    櫻井慎太郎, 川崎英也

    第68回コロイドおよび界面化学討論会  2017年9月 

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  • プリンテッドエレクトロニクス用銅系インクのための銅ナノ粒子設計

    川崎英也

    第35回関西界面科学セミナー  2017年6月 

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  • 表面支援レーザー脱離イオン化法(SALDI)による有機低分子の質量分析

    川崎英也

    理研シンポジウム 分子構造解析2017  2017年6月 

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  • Agドープによるグルタチオン保護Auクラスターの高効率発光と凝集誘起型の発光特性

    彦惣 大輝, 川﨑 英也, 彦惣大輝, 川﨑英也

    第77回分析化学討論会  2017年5月 

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  • 包接能を有する新規MALDI用マトリックスの合成と性能評価

    安達吉宏, 川野真太郎, 佐藤博文, 小野大助, 川崎英也, 荒川隆一, 靜間基博

    第65回質量分析学会  2017年5月 

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  • 金ナノクラスターの合金化による高効率発光と1O2生成

    彦惣 大輝, 川﨑 英也, 彦惣大輝, 川﨑英也

    ナノ学会第15回大会  2017年5月 

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  • 100℃以下熱焼結を可能にする低温焼成型銅ナノインクの開発

    梶本栄一, 川崎英也, 梶本栄一, 川崎英也

    ナノ学会第15回大会  2017年5月 

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  • リパーゼ選択性蛍光プローブの設計合成とその分光特性

    佐藤 博文, 三輪 真之, 靜間 基博, 川崎 英也, 荒川 隆一

    日本化学会 第97春季年会  2017年3月 

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  • 白金イオン/界面活性剤自己集合体を利用した白金ナノデイスクの作製

    川崎 英也

    日本セラミック協会・セラミックス  2008年 

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産業財産権

  • 混合インク及びその製造方法、並びに、混合インクの焼結方法

    川▲崎▼ 英也, 友利 大介

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    出願人:学校法人 関西大学

    出願番号:特願2020-180857  出願日:2020年10月

    公開番号:特開2022-071739  公開日:2022年5月

    J-GLOBAL

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  • 表面上の第四級アンモニウムカチオン並びに/又は金及び/若しくは銀のハロゲン化物の量が低減された金ナノ粒子の懸濁液

    宮澤 雄太, 溝口 大剛, 川▲崎▼ 英也, 岩崎 泰彦, 西田 圭佑

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    出願人:大日本塗料株式会社, 学校法人 関西大学

    出願番号:特願2019-230394  出願日:2019年12月

    公開番号:特開2020-050960  公開日:2020年4月

    J-GLOBAL

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  • 炭素量子ドットおよびその製造方法

    川▲崎▼ 英也, 三木 恵太, 日高 康博, 河村 昌信

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    出願人:学校法人 関西大学, 日本製紙株式会社

    出願番号:特願2019-219277  出願日:2019年12月

    公開番号:特開2021-088477  公開日:2021年6月

    J-GLOBAL

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  • 音増感剤及びその製造方法

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    出願番号:特願2019-133414  出願日:2019年7月

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  • 音増感剤及びその製造方法

    川▲崎▼ 英也, 山本 健

     詳細を見る

    出願人:学校法人 関西大学

    出願番号:特願2019-133414  出願日:2019年7月

    公開番号:特開2021-017408  公開日:2021年2月

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  • 銅ナノ粒子、銅ナノ粒子分散体、接合用ペースト、物品及びその製造方法

    川▲崎▼ 英也, 上杉 隆彦

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    出願人:学校法人 関西大学, 東洋インキSCホールディングス株式会社

    出願番号:特願2019-109239  出願日:2019年6月

    公開番号:特開2020-200517  公開日:2020年12月

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  • 導電性インキ組成物及び導電性積層体

    川▲崎▼ 英也, 櫻井 慎一郎, 矢内 宏幸, 上杉 隆彦

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    出願人:学校法人 関西大学, 東洋インキSCホールディングス株式会社

    出願番号:特願2019-066667  出願日:2019年3月

    公開番号:特開2020-164649  公開日:2020年10月

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  • 銅粒子混合物及びその製造方法、銅粒子混合物分散液、銅粒子混合物含有インク、銅粒子混合物の保存方法及び銅粒子混合物の焼結方法

    川▲崎▼ 英也

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    出願人:学校法人 関西大学

    出願番号:JP2018014637  出願日:2018年4月

    公表番号:WO2018-190246  公表日:2018年10月

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  • 銅粒子混合物及びその製造方法、銅粒子混合物分散液、銅粒子混合物含有インク、銅粒子混合物の保存方法及び銅粒子混合物の焼結方法

    川▲崎▼ 英也

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    出願人:学校法人 関西大学

    出願番号:特願2019-512483  出願日:2018年4月

    特許番号/登録番号:特許第6976597号  登録日:2021年11月 

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  • 抗菌剤およびその製造方法

    川▲崎▼ 英也, 富永 千明

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    出願人:学校法人 関西大学

    出願番号:特願2018-048336  出願日:2018年3月

    公開番号:特開2019-156794  公開日:2019年9月

    特許番号/登録番号:特許第6941871号  登録日:2021年9月 

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  • 抗菌剤およびその製造方法

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    出願番号:特願2018-048336  出願日:2018年3月

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  • 抗菌剤およびその製造方法

    川▲崎▼ 英也, 富永 千明

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    出願人:学校法人 関西大学

    出願番号:特願2018-048336  出願日:2018年3月

    公開番号:特開2019-156794  公開日:2019年9月

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  • 表面上の第四級アンモニウムカチオン並びに/又は金及び/若しくは銀のハロゲン化物の量が低減された金ナノ粒子の懸濁液

    宮澤 雄太, 溝口 大剛, 川▲崎▼ 英也, 岩崎 泰彦, 西田 圭佑

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    出願人:大日本塗料株式会社, 学校法人 関西大学

    出願番号:特願2017-177879  出願日:2017年9月

    公開番号:特開2018-053361  公開日:2018年4月

    特許番号/登録番号:特許第6692042号  登録日:2020年4月 

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  • 表面上の第4級アンモニウムカチオン並びに/又は金及び/若しくは銀のハロゲン化物の量が低減された金ナノ粒子の懸濁液

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    出願番号:特願2017-177879  出願日:2017年9月

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  • 表面上の第四級アンモニウムカチオン並びに/又は金及び/若しくは銀のハロゲン化物の量が低減された金ナノ粒子の懸濁液

    宮澤 雄太, 溝口 大剛, 川▲崎▼ 英也, 岩崎 泰彦, 西田 圭佑

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    出願人:大日本塗料株式会社, 学校法人 関西大学

    出願番号:特願2017-177879  出願日:2017年9月

    公開番号:特開2018-053361  公開日:2018年4月

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  • 銅微粒子混合物及びその製造方法、銅微粒子混合物分散液、銅微粒子混合物含有インク、銅微粒子混合物の保存方法及び銅粒子混合物の焼結方法

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    出願番号:特願2017-080971  出願日:2017年4月

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  • 銅粒子構造体及び銅インク

    坂井田 俊, 出村 隆充, 川▲崎▼ 英也

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    出願人:株式会社村田製作所, 学校法人 関西大学

    出願番号:特願2017-012050  出願日:2017年1月

    公開番号:特開2018-119187  公開日:2018年8月

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  • 銅粒子構造体及び銅インク

    坂井田 俊, 出村 隆充, 川▲崎▼ 英也

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    出願人:株式会社村田製作所, 学校法人 関西大学

    出願番号:特願2017-012050  出願日:2017年1月

    公開番号:特開2018-119187  公開日:2018年8月

    特許番号/登録番号:特許第6968543号  登録日:2021年10月 

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  • 銅粒子構造体及び銅インク

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    出願番号:特願2017-012050  出願日:2017年1月

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  • 炭素量子ドットの製造方法及びその方法で得られる炭素量子ドット

    川▲崎▼ 英也, 野崎 孝至

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    出願人:学校法人 関西大学

    出願番号:特願2016-168913  出願日:2016年8月

    公開番号:特開2018-035035  公開日:2018年3月

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  • 炭素量子ドットの製造方法及びその方法で得られる炭素量子ドット

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    出願番号:特願2016-168913  出願日:2016年8月

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  • 抗菌剤およびその製造方法

    川▲崎▼ 英也, 富永 千明, 長谷川 裕美

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    出願人:学校法人 関西大学

    出願番号:特願2016-087232  出願日:2016年4月

    公開番号:特開2017-197442  公開日:2017年11月

    特許番号/登録番号:特許第6654320号  登録日:2020年2月 

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  • 抗菌剤およびその製造方法

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    出願番号:特願2016-087232  出願日:2016年4月

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  • 抗菌剤およびその製造方法

    川▲崎▼ 英也, 富永 千明, 長谷川 裕美

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    出願人:学校法人 関西大学

    出願番号:特願2016-087232  出願日:2016年4月

    公開番号:特開2017-197442  公開日:2017年11月

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  • 銅ナノ粒子及びその製造方法、銅ナノ粒子分散液、銅ナノインク、銅ナノ粒子の保存方法及び銅ナノ粒子の焼結方法

    川▲崎▼ 英也, 荒川 隆一, 穂北 祐樹

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    出願人:学校法人 関西大学

    出願番号:特願2016-505139  出願日:2015年2月

    特許番号/登録番号:特許第6297135号  登録日:2018年3月 

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  • 白金ナノ粒子の物理蒸着を用いたイメージング質量分析方法

    荒川 隆一, 川▲崎▼ 英也, 小澤 智行

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    出願人:学校法人 関西大学, 日産化学工業株式会社

    出願番号:特願2013-558757  出願日:2013年2月

    特許番号/登録番号:特許第6203056号  登録日:2017年9月 

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  • 銅ナノ粒子の製造方法

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    出願番号:特願2013-0265352  出願日:2013年2月

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  • ビニルエーテルの製造方法、ビニル交換反応用触媒、及びエーテル交換反応用触媒

    大洞 康嗣, 川▲崎▼ 英也, 北村 浩士, 高瀬 一郎, 楢▲崎▼ 美也

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    出願人:学校法人 関西大学, 株式会社ダイセル

    出願番号:特願2012-221085  出願日:2012年10月

    公開番号:特開2014-073980  公開日:2014年4月

    特許番号/登録番号:特許第6213707号  登録日:2017年9月 

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  • ビニルエーテルの製造方法、ビニル交換反応用触媒、及びエーテル交換反応触媒

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    出願番号:特願2012-221085  出願日:2012年10月

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  • 分散安定性の高い銅ナノ粒子の製造方法

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    出願番号:PCT/JP2012/58171  出願日:2012年3月

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  • 白金ナノ粒子の物理蒸着を用いたイメージング質量分析方法

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    出願番号:特願2012-033258  出願日:2012年2月

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  • 分散安定性の高い銅ナノ粒子の製造方法

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    出願番号:特願2011-196237  出願日:2011年9月

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  • 遷移金属超微粒子からなるクロスカップリング用触媒およびそれを用いたクロスカップリング法

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    出願番号:特願2010-139638  出願日:2010年7月

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  • 質量分析用基板及びその製造方法

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    出願番号:特願2010-141352  出願日:2010年6月

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  • 試料捕捉合金、質量分析装置、質量分析方法、試料捕捉方法、試料捕捉合金、試料捕捉合金製造方法

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    出願番号:2009-171507  出願日:2009年7月

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  • 質量分析用基板及びその製造方法並びに質量分析法

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    出願番号:特願2009-163318  出願日:2009年7月

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  • ナノ粒子蛍光体の製造方法

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    出願番号:特願2009-154932  出願日:2009年6月

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  • 質量分析用基板及びその製造方法並びに質量分析法

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    出願番号:特願2008-332164  出願日:2008年12月

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  • 高分子化合物の分析法

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    出願番号:特願2007- 277230  出願日:2007年10月

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  • MALDI質量分析測定のためのナノ粒子担持イオン化基板の製造方法とその用途

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    出願番号:特願2007- 36658  出願日:2007年2月

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  • 固/液界面吸着ミセル膜を反応場として形成される単結晶質の貴金属超薄膜ナノ粒子及びその製造法

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    出願番号:特願2005-057159  出願日:2005年3月

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  • 金属微粒子の製造方法とその含有組成物

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    出願番号:特願2004-116254  出願日:2004年4月

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  • 金ナノロッドの調製法

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    出願番号:特願2003-31420  出願日:2003年9月

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  • 金ナノロッドの調製法

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    出願番号:特願2003-135062  出願日:2003年5月

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  • 金ナノロッドの製造方法

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    出願番号:特願2003-208691 

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  • 金ナノロッドの製造方法と用途

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    出願番号:特願2004-024006 

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▼全件表示

受賞

  • 論文賞

    2023年5月   日本質量分析学会  

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  • 接合科学共同利用・共同研究賞

    2023年5月   大阪大学接合科学研究所   もみ殻由来シリカ複合ナノ粒子の創製と新奇光抗菌剤としての展開

    川﨑 英也, 宮治 裕史, 梅田 純子, 近藤 勝義

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  • 論文賞

    2017年5月   日本質量分析学会  

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    受賞国:日本国

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  • 論文賞

    2016年5月   日本質量分析学会  

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    受賞国:日本国

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  • 科学奨励賞

    2011年5月   日本質量分析学会  

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    受賞国:日本国

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  • 優秀論文賞

    2007年5月   日本質量分析学会  

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    受賞国:日本国

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  • 科学奨励賞

    2003年9月   日本化学会 コロイドおよび界面化学部会  

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    受賞国:日本国

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  • 松浦賞

    1999年8月   日本化学会 コロイドおよび界面化学部会 九州支部  

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    受賞国:日本国

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▼全件表示

共同研究・競争的資金等の研究課題

  • 熱活性化ワイドギャップ半導体シングルナノ粒子による熱触媒機能の開拓

    研究課題/領域番号:22H01915  2022年4月 - 2025年3月

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    川崎 英也, 山本 健

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    配分額:16380000円 ( 直接経費:12600000円 、 間接経費:3780000円 )

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  • 低温・敏速造形を実現する金属3Dプリンター用合金ナノペーストの開発

    研究課題/領域番号:20K21095  2020年7月 - 2022年3月

    日本学術振興会  科学研究費助成事業 挑戦的研究(萌芽)  挑戦的研究(萌芽)

    川崎 英也, 上田 正人

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    配分額:6240000円 ( 直接経費:4800000円 、 間接経費:1440000円 )

    本研究では、金属3Dプリンタ用導電材料として、液体金属に銅粒子を分散させた導電ペースト(以下、LTGCペーストと呼ぶ)の開発を目的とした。その結果、従来の高温溶融させた液体金属を冷却凝固させる方法ではなく、室温で液体の液体金属(ガリウム-インジウム共晶(EGaIn))と銅粒子との合金反応による融点上昇により液体金属を凝固する新たな視点からの金属導電ペーストの開発することができた。LTGCペーストは、180℃の低温で硬化反応を示し、このLTGCペースト調製には、(1)乳酸添加によるGaとCuの合金化促進、エッジ(端部)部分に高い活性面を有する扁平銅粒子の組み合わせが、重要であることを明らかした。

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  • 光殺菌と組織再生効果を併せ持つ新しい歯周病治療用ゲル剤の開発

    研究課題/領域番号:19K10102  2019年4月 - 2022年3月

    日本学術振興会  科学研究費助成事業 基盤研究(C)  基盤研究(C)

    加藤 昭人, 川崎 英也, 宮治 裕史, 竹生 寛恵

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    配分額:4290000円 ( 直接経費:3300000円 、 間接経費:990000円 )

    抗菌的光線力学療法(a-PDT)は,光照射と光増感剤を用いて発生させた一重項酸素によって殺菌する治療法である.本研究では,光増感剤の金銀ナノクラスター,およびローズベンガルをカチオン性の高分子であるキトサンで包含したナノゲルを創製し,光線力学的特性を調べた.また,抗菌・抗バイオフィルム性を評価するとともに細胞毒性を評価した.その結果,白色LED照射によるa-PDTは,口腔内バイオフィルム感染症に効果的である可能性が示唆された.

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  • 量子ドット音増感剤の開拓と難治性感染症治療への応用

    研究課題/領域番号:19H02564  2019年4月 - 2022年3月

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    川崎 英也, 山本 健, 宮治 裕史

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    配分額:14170000円 ( 直接経費:10900000円 、 間接経費:3270000円 )

    本研究では、超音波キャビテーションにより金ナノクラスター(数十個の金原子集合体)を励起することで、酸化力の強い一重項酸素(1O2)が生成する機構(音増感作用)を明らかにし、殺細胞・細菌を局部的に行う超音波治療法へ展開することを目的とした。Au NCs音増感作用による高い1O2生成効率の達成にはAu NCsの自身の高い1O2生成量だけでなく、1O2による自己酸化による1O2損失が小さいことが重要であることが示された。金属と分子の中間の性質を持つ金144量体(Au144 NCs)が最も高い音増増感作用を示した。そして、生細胞に対する音増感剤Au144 NCsの効果を明らかにした。

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  • 自在な立体制御を目指した有機・酵素ワンポット不斉合成反応の開発

    研究課題/領域番号:17K07785  2017年4月 - 2020年3月

    日本学術振興会  科学研究費助成事業 基盤研究(C)  基盤研究(C)

    佐藤 博文, 渡辺 嘉, 川崎 英也

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    配分額:4680000円 ( 直接経費:3600000円 、 間接経費:1080000円 )

    酸化マンガン/過マンガン酸カリウムを用いた酸化反応とラクトバチルスケフィア由来のアルコールデヒドロゲナーゼを組み合わせた1-フェニルエタノールの立体制御について研究を行った。この反応は単純な混合系では金属による酵素の失活により全く進行しなかったが、金属酸化剤の反応をポリジメチルシロキサンの膜容器 (PDMSティンブル) 内相で行い、反応後外相にイソプロピルアルコールを添加した酵素液を添加することにより、酸化反応によって生成した1-フェニルメチルケトンを外相に拡散させて外相で酵素による不斉還元を行うことができた。反応は最大86%の転化率で進行し、得られた光学純度は>99%eeであった。

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  • 抗菌能持続性を有する熱可塑性樹脂用途向けの有機無機ハイブリッド型抗菌剤の開発

    2017年

    科学技術振興機構  産学が連携した研究開発成果の展開 研究成果展開事業 地域産学バリュープログラム 

    川崎 英也

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    担当区分:研究代表者 

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  • 樹脂用途向けの有機無機ハイブリッド型抗菌剤の開発

    2016年

    科学技術振興機構  産学が連携した研究開発成果の展開 研究成果展開事業 マッチングプランナープログラム 

    川崎 英也

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  • 動的架橋ゲルを用いた時空間制御型スマート医用システムの創出

    研究課題/領域番号:15H03026  2015年4月 - 2018年3月

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    宮田 隆志, 川崎 英也

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    配分額:16770000円 ( 直接経費:12900000円 、 間接経費:3870000円 )

    本研究では,動的架橋として生体分子複合体形成や光二量化を用いて動的架橋ゲルを合成し,その利用によって時間的・空間的に制御できるスマート医用システムの創出を目指した。特に,薬物を動的架橋部位に利用したゲルを合成し,その動的構造変化による薬物放出の制御を行った。また,分子認識能を有する動的架橋ゲルと金属とのハイブリッド化により,新しい生体分子センサーを調製した。さらに,生体分子応答性や光応答性を示す動的架橋ゲルを細胞培養環境(スマートニッチ)として利用し,スマート細胞制御システムの構築も試みた。

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  • 抗菌光線力学療法のための新しい光増感性金ナノクラスターの開発

    研究課題/領域番号:15H03520  2015年4月 - 2018年3月

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    川崎 英也, 宮治 裕史, 大坂 一生, 田村 裕, 古池 哲也

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    配分額:15080000円 ( 直接経費:11600000円 、 間接経費:3480000円 )

    本研究では、金ナノクラスター(AuNCs)(約1nmの金粒子)を光増感剤とする一重項酸素(1O2,活性酸素の一つで強い酸化力がある)発生メカニズムを明らかにし、1O2を大量発生するAuNCsを創出することを目的とした。AuNCsを含む種々の新規光増感剤(金銀合金ナノクラスター、AuNCsとタンパク質複合体、AuNCsと天然高分子との複合ナノゲル)を開発し、その光増感作用により発生する1O2が歯周病の殺菌に有効であることを見出した。20歳以上の約80%の人が歯周病といわれている状況下で、AuNCsを用いたa-PDT治療は、新しい歯周病治療法として、歯周病患者の治療に貢献できると期待される。

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  • 新規なイオン化法を利用したイメージング質量分析の開発

    研究課題/領域番号:26505011  2014年4月 - 2017年3月

    日本学術振興会  科学研究費助成事業 基盤研究(C)  基盤研究(C)

    荒川 隆一, 川崎 英也

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    配分額:4940000円 ( 直接経費:3800000円 、 間接経費:1140000円 )

    研究代表者らが新しく考案した2種類のイオン化法である1) 白金スパッタ蒸着法を利用したレーザー脱離イオン化(Pt-SALDI)と2) タッピング型走査プローブエレクトロスプレーイオン化(t-SPESI)を利用して、新規なイメージング質量分析(IMS)法の開発を行った。Pt-SALDI-IMSにおいて、浸透性農薬を投与した植物の葉を試料として、植物内における農薬の分布の経時変化を追跡した。一方、内径150 nmのキャピラリーを持つナノピペットを用いたt-SPESIにおいて、OHPフィルム上に描いた赤色インクパターンの質量分析イメージングの結果、従来を超える10 μm以下の空間分解能を達成できた。

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  • 低温焼結可能な耐酸化性を有する銅ナノ粒子の大量合成

    2012年

    科学技術振興機構  産学が連携した研究開発成果の展開 研究成果展開事業 研究成果最適展開支援プログラム(A-STEP) 実用化挑戦タイプ 中小・ベンチャー開発 

    川崎 英也

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  • レアメタル触媒の高度利用に向けた保護剤フリーでの金属サブナノクラスターの液中合成

    研究課題/領域番号:23360361  2011年4月 - 2014年3月

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    川崎 英也, 荒川 隆一

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    配分額:16770000円 ( 直接経費:12900000円 、 間接経費:3870000円 )

    本研究は、チオール化合物などの保護剤を使用せずに金属ナノクラスターを液中合成する方法を開発することを目的とした。N,N-ジメチルホルムアミド(DMF)を含むホルムアミド系溶媒を還元剤&保護剤とすることで,金ナノクラスターを液中合成できることを見出し,その触媒特性を評価した。本合成法は、金以外の他金属へと拡張でき、DMF溶媒で保護されたCu、Pd、Pt、及びFeクラスター(ナノ粒子)の合成を実現した。金属クラスターの質量分析として,大気圧レーザースプレーイオン化(LSI)質量分析装置を試作、及び金属クラスターのMALDI-MSにおいて有効な新規マトリックスを開発した。

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  • 低分子化合物とタンパク質の結合評価のための銀ナノプレート集積体バイオチップの創成

    研究課題/領域番号:23655074  2011年 - 2012年

    日本学術振興会  科学研究費助成事業 挑戦的萌芽研究  挑戦的萌芽研究

    川崎 英也, 荒川 隆一

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    配分額:3510000円 ( 直接経費:2700000円 、 間接経費:810000円 )

    本研究の目的は,分子標的創薬や個別化医療の実現に貢献する「標的タンパク質と複数の低分子薬物の特異的な結合様式を解明」するための質量分析と分光分析を連携させた新規な分析手法を開発した。局在表面プラズモン(LSPR)センサーによる相互作用解析とレーザー脱離イオン化法質量分析(LDI-MS)による結合物の同定・構造解析を同一試料基板で行うことができる三角形状銀ナノ構造体チップを作成した。この構造体チップを用いたLSPR/LDI-MS連携させた分析手法を開発した。

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  • ナノ粒子の集積体表面を利用した新規な大気圧レーザー脱離ソフトイオン化法の開発

    研究課題/領域番号:22350040  2010年4月 - 2014年3月

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    荒川 隆一, 川崎 英也

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    配分額:15210000円 ( 直接経費:11700000円 、 間接経費:3510000円 )

    金属ナノ粒子を利用した表面支援レーザー脱離イオン化(SALDI)は、低分子量域(<500 Da)に妨害イオンがなく良好なスペクトルが得られる。本研究の目的は、低分子量の化合物を簡便に質量分析(MS)するための新しい”大気圧(AP)”-SALDIの開発である。新規に創製したナノ粒子構造体を用いてAP-SALDIのイオン化の特性を調べたが、AP-SALDIはソフトなイオン化であるが検出感度は低かった。SALDIの新規技術として、1) 局在表面プラズモン共鳴とSALDI-MSを結合した分子同定法、2) 磁性ナノ粒子によるアフィニテーSALDI-MS、3) Pt蒸着によるMSイメージングを開発した。

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  • 表面ナノ加工基板を用いた表面支援レーザー脱離イオン化質量分析システム

    研究課題/領域番号:21310072  2009年 - 2011年

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    米澤 徹, 藤井 正明, 石内 俊一, 荒川 隆一, 川崎 英也

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    配分額:18460000円 ( 直接経費:14200000円 、 間接経費:4260000円 )

    低分子の解析に最適なナノ基板を用いる表面支援LDI(SALDI)システムの開拓を行った。合金からのDealloy法によって、電気化学的エッチングによりナノポーラス白金基板の作製を行い、成功した。また、合金組成の違いによって、ナノポーラス構造が大きく変化していることを見出した。この基板をSALDIに用いたが、有機化合物の脱離・イオン化は熱拡散により困難であった。それに対し、半導体微粒子の集積法によるLDI用試料基板形成を行い、LDI質量分析に用いたところ、効率よく化合物が脱離・イオン化されることが明確となった。

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  • ナノ粒子積層薄膜プレートの構築と環境バイオセンシング技術への応用

    研究課題/領域番号:20710091  2008年 - 2009年

    日本学術振興会  科学研究費助成事業 若手研究(B)  若手研究(B)

    川崎 英也

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    配分額:3510000円 ( 直接経費:2700000円 、 間接経費:810000円 )

    本研究は、環境バイオセンシング技術への応用を目指して、表面支援レーザー脱離イオン化質量分析(SALDI-MS)のための新規なSALDIプレートの開発を目的としている。その研究成果として、SALDI-MSのための新規なナノ粒子積層薄膜プレート、(1)金ナノ粒子/高分子交互積層薄膜と(2)ポリエチレンイミン修飾グラファイトシートを開発した。金ナノ粒子/高分子交互積層薄膜では、フェムトモルオーダのペプチドの高感度検出、分子量1万程度の蛋白質の検出など、従来の金ナノ粒子を用いたSALDIに比べて、感度と検出限界分子量ともに向上できた。環境分析を目的としたポリエチレンイミン修飾グラファイトシートでは、近年、環境残留の点で問題となっている炭化フッ素系の界面活性剤(PFOS,PFA)の高感度検出と定量分析の有効性を示すことができた。

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  • ナノ粒子の2次元規則配列表面を利用した新規なレーザー脱離ソフトイオン化法の開発

    研究課題/領域番号:19350045  2007年 - 2009年

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    荒川 隆一, 川崎 英也

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    配分額:15210000円 ( 直接経費:11700000円 、 間接経費:3510000円 )

    本研究は、近年、ライフサイエンス分野・環境分野において低分子物質分析の重要な地位を築きつつある有機マトリックスを用いない表面支援レーザー脱離イオン化質量分析(SALDI-MS)のための新規なSALDIプレートの開発を目的としている。本研究では、SALDI-MSのためのナノ粒子の2次元規則配列表面をもつLDIプレート(ナノ粒子を含む)として、計4つの新規なプレートを開発した。(1)白金ナノフラワー、(2)ロッド状酸化亜鉛ナノ粒子、(3)尿素表面修飾酸化チタニア粒子、及び(4)スルホン基修飾FePtCu磁性ナノ粒子が有効であることを見出した。

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  • 金ナノロッド単粒子薄膜を利用した新規センシング技術の開発

    研究課題/領域番号:18310069  2006年 - 2008年

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    新留 康郎, 川崎 英也

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    配分額:16880000円 ( 直接経費:15200000円 、 間接経費:1680000円 )

    リン脂質修飾金ナノロッドを凝集させ、さらに乾燥させた後に、溶液中に再分散できる条件を見いだした。リン脂質修飾金ナノロッドには過剰な界面活性剤や高分子を含まず、最小限のリン脂質とカチオン性界面活性剤でその分散安定性が保たれている状態である。このため、乾燥した金ナノロッドは金属光沢を示した。この状態で金ナノロッドを冷蔵庫に保管することで不可逆な凝集を抑制できることがわかった。これは新しい金属ナノ粒子の保管方法・表面修飾方法として他に例を見ないものであり、今後の学術的あるいは応用に向けた研究展開が期待される。
    液液界面を利用した単粒子薄膜作製法により、金ナノロッドの凝集状態を制御できることを明らかにするとともに、高分子電解質で表面修飾した金ナノロッドをガラス基板に静電相互作用で固定する方法を確立した。基板に固定した金ナノロッドは明確な表面プラズモンバンドを示すことから、ナノロッドが孤立状態で固定できることが明らかになった。この金ナノロッドに抗体を固定し、更に抗原となるタンパク質を結合させた。それぞれのステップで表面プラズモンバンドの変化をモニターしたところ、抗体・抗原の吸着に伴って再現性の良いピークシフトが得られることを明らかにした。この実験によって得られたピークシフトは従来の報告にない大きなものであり、金ナノロッドセンサーの実用化に向けた大きな技術的進歩が得られた。また、検出感度も10-10 M のオーダーの下限を有しており、今後の最適化によって従来のセンサーを上回る検出感度を実現できることが明らかになった。

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  • 固液界面ナノ自己集合体を利用した金属ナノ粒子のナノ構造配列制御

    研究課題/領域番号:18710102  2006年 - 2007年

    日本学術振興会  科学研究費助成事業 若手研究(B)  若手研究(B)

    川崎 英也

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    配分額:2700000円 ( 直接経費:2700000円 )

    本研究では、一次構造(粒径、形態)、並びに二次構造(粒子配列)が制御された貴金属(金、白金)ナノ粒子を自己組織的に固体基板上に実現することを目標とする。本年度は当初計画にはなかったが、生体分子の表面支援レーザ脱離イオン化質量分析法(SALDI-MS)のためのレーザ脱離イオン化支援基板として、形態制御された金属(金、白金)ナノ粒子担持基板が極めて有効であることを新たに発見し、展開することができた。
    1.金ナノ粒子積層担持シリコン基板
    金ナノ粒子を積層配列させた基板では、アンジオテンシンIの検出感度は数百アットモルであり、金ナノ粒子を単層吸着させた基板と比べ、その感度は約100倍に増大することがわかった。更に、金ナノ粒子の積層数を増やすことにより、従来法では検出が困難とされているインスリン(m/z>5000)やシトクロムC(m/z>12000)などの低分子タンパク質の検出も可能となった.加えて、金ナノ粒子積層基板は、試料を薄膜内に濃縮できるため、濃縮プレートとしての機能をもつSALDIプレートとしても有効であることを見出した。
    2.白金ナノフラワー担持基板
    SALDI用の新規なナノ物質として、ナノメートルレベルの突起部分を持つ白金ナノ構造体(白金ナノフラワー)を創製した。この白金ナノフラワーを用いて測定したアンジオテンシンIの検出感度は0.7fmolであり、チトクロムCもSALDI-MSで良好に検出できた。これに対し、球状の白金ナノ粒子では、アンジオテンシンIの検出感度は100fmol程度であり、チトクロムCも検出できなかった。これは、白金ナノフラワーに特徴的なナノメートルレベルの突起部分がアンジオテンシンIのイオン化効率の向上に寄与していることを示す。このように、ナノ粒子の形状・構造制御がSALDI-MSに有効であることを見出した。

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  • 温度変化によるベシクルの可逆分散・凝集の解明と可溶化分離への展開

    研究課題/領域番号:15750121  2003年 - 2004年

    日本学術振興会  科学研究費助成事業 若手研究(B)  若手研究(B)

    川崎 英也

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    配分額:2400000円 ( 直接経費:2400000円 )

    本研究では,自発的にベシクルが形成される条件を見いだし、外部環境変化(特に、温度)によって生じる自発形成ベシクルの可逆分散・凝集の機構を解明する。そして、このベシクルの可逆分散・凝集を、水溶液中の水微溶性物質を効率的に分離回収すること(可溶化分離)へと応用展開することを目的としている。具体的には、この研究により、以下の研究成果を行った。
    (1)自発形成ベシクルの構築:
    自発的にベシクルが形成される3つの系を新たに見いだした。(I)テトラデシルジメチルアミンオキシド(界面活性剤)にナフタレンスルホン酸塩を半等量添加することによって生じる自発形成ベシクル。(II)天然由来のアルギニン脂肪酸塩から生じる自発形成ベシクル。(III)二本鎖型界面活性剤、ジデシルジメチルアミンオキシドのプロトン化によって生じる自発形成ベシクル。
    (2)ベシクルの分散・凝集:
    上記の(I)のベシクルに関しては、ベシクルの分散挙動が、ナフタレンスルホン酸塩添加量と界面活性剤濃度の比によって決定されていることを見いだし、そのベシクルの分散挙動は、コロイド粒子間の相互作用を記述するDLVO理論で説明できることを明らかにした。更に、上記の(I)のベシクルに関しては、対イオン結合が温度変化に依存することから生じる、温度変化によるベシクルの分散・凝集を初めて示した。上記(II,III)のべシクルについては、pH変化によりベシクルの分散・凝集が生じることを見いだした。
    (3)ベシクルによる疎水性物質の水中からの除去:
    疎水性物質(スダンIII、ベンゼン)を可溶化したベシクルの分散・凝集を利用することにより、疎水性物質を水中から除去できる結果を得ることができ、可溶化分離法の有用性を示すことができた。

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  • 両親媒性物質のナノスケール構造の物理的因子による制御

    研究課題/領域番号:12440200  2000年 - 2002年

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    前田 悠, 川崎 英也, 懸橋 理枝, 深田 和宏

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    配分額:14700000円 ( 直接経費:14700000円 )

    1.pH変化によるミセル-ベシクル転移 オレイルジメチルケミシオキシドに(O1DMAO)のpHによるミセル-ベシクル転移が自発的かつ可逆的であることを昨年度示したが無添加塩系では常にミセル-ベシクルが共存していた。今年度は添加塩として10mMNaCl中でのpHによるミセル-ベシクル転移を調べた。途中のイオン化状態(0.3)では結合網目が明瞭に観測された。そして0.4ではミセルとベシクルが共存し、0.5ではベシクルのみの系が実現した。従って、ミセルとベシクルの二状態間の相転移ではなく、イオン化度の増加とともに、曲率(充填因子)が連続的に変化する過程であることが結論できた。
    2.疎水性体イオンによる構造形成 C14DMAOのカチオン状態と半等量プロトン化状態において、2-ヒドロキシナフタレンスルフォン酸(NphS)のNa塩との相互作用を調べた。その結果、炭素鎖長14であるにも拘わらず、他の炭素鎖長16のカチオン性界面活性剤よりも曲率の小さい構造(ラメラ、ベシクル)が形成された。これはラメラにおいて極性基間に水素結合などの引力的相互作用により充填因子が増大した結果と考えられアミンオキシドに特徴的な現象である。
    3.グラファイト/溶液界面の凝集体構造 C12DMAOのグラファイト表面への液相吸着により、非イオン種ではヘミミセルが生成したが、半等量プロトン化状態では単分子膜となり、pHによる構造転移が観測された。
    4.アルキルジメチルアミンオキシド(CnDMAO)/オレイン酸ナトリウム(NaOl)系の分散状態と複合体形成 n=16,14,12,10,8,6の非イオン種CnDMAOとNaOlの等モル混合物の溶液のpHを低下させたときの相分離を調べた。いづれの場合もある臨界pH(pH_c)において相分離が起こった。この臨界pH(pH_c)はn=10において最小を示した.この挙動は、形成される複合体がnが10以上と8以下では異なることによると結論した。nが10以上の場合は、catanionic複合体が形成される。他方、nが8以下になると酸性石鹸が形成される。この場合,catanionic複合体も形成される。
    5.イオン/非イオン混合ミセルのコリン-ハーキンス係数の電荷密度依存性 他の混合ミセルでは実行困難なcmcにおけるミセル組成の制御をアミンオキシドの特徴をいかして可能にした。その結果、低電荷密度まで、CH係数とイオンと対イオン結合度は一致することを実験的に初めて示すことに成功した。
    6.イオン性/非イオン性混合ミセルの対イオン結合度のミセル組成依存性の理論 イオン性ミセルの対イオン結合度が既知の場合、そのミセルに非イオン種が混合した場合の対イオン結合度の変化を表す解析式を導いた。この式は12種の報告例を良く記述できた。

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  • 体積相転移を示すゲルの収縮相の構造と特性

    研究課題/領域番号:98J07089  1998年 - 1999年

    日本学術振興会  科学研究費助成事業 特別研究員奨励費  特別研究員奨励費

    川崎 英也

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    配分額:2400000円 ( 直接経費:2400000円 )

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社会貢献活動

  • 日本分析化学会:関西支部常任幹事

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  • 日本化学会 界面コロイド部会 :関西支部副支部長(幹事),事業企画委員, 及び討論会委員

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  • 日本油化学会 :関西支部幹事

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  • 日本質量分析学会 :討論会委員

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  • Editorial Board:Mass Spectrometry (2019-)

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  • Editorial Board:Analytical Sciences (2017-)

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教育内容・方法の工夫(授業評価等を含む)

  • 1. パワーポイントによるビジュアル資料作成、要点プリントを用いた復習講義の実施、講義資料のweb公開 マルチメディア機器を活用した授業方法を導入して、板書による講義と連動させ、聴視覚からの理解力の向上を目指した。パワーポイントの資料は、インフォメーションシステム(Web)上で公開した。加えて、講義内容についての要点プリントを用いた復習講義(演習を含む)で理解のポイントを示すことで、学生の理解度向上をはかった。また、授業外における学習促進のため、要点プリントをWeb上で公開し、自宅での復習や宿題にも活用できるようにした。 2. 授業評価の実施と活用方法 学生による授業評価は、Web或いは紙ベースによるアンケートで行った。授業評価による要望によって開始した要点プリントを用いた復習講義と自学自習用の資料のweb公開の実施は、理解のポイントがわかりやすくなったと評価を得た。

作成した教科書、教材、参考書

  •  特になし

教育方法・教育実践に関する発表、講演等

  • 1. 日本分析化学会近畿支部主催「分析化学教育を考える」 2010年1月9日 分析化学実験の現状について口頭発表を行い、他大学の教員と情報交換を行った。

その他教育活動上特記すべき事項

  • 1. 高大連携の推進に向けた取り組みとして、「JST未来の科学者要請講座」 2010年11月20日 中学生・高校生を対象に「ナノテクノロジー」に関する講義と実験を行った。 2. ?私立大学情報教育協会による分野別教育における情報教育(化学系)の中間まとめについて協力 2010年4月14日 3. ?私立大学情報教育協会主催平成21年度FDのための情報技術講習会 2009年3月11日-13日 情報通信技術を取り入れた効果的な授業の設計と授業の進め方について、受講の動機付け及び授業参加意欲の喚起を含めて、授業マネージメントの観点から授業デザインの構築に必要な基本知識・技能の習得のための実習・講義に参加した。 4. セミナー:コミュニュケーション教育とデザイン教育(発想教育) 講師岡山大学創造工学センター長塚本真也教授、2007年8月26-27日 教科書「創造力育成の方法」を用いて創造力を伸長するPBL教育法についてセミナーに参加し、本教育法を講義に取り入れた。