Publishing type：Research paper (scientific journal)   Publisher：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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Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

A facile preparation method of an ion gel that exhibits high strength and repeated stretchability is realized. A number of polymer chain entanglements in addition to a small number of chemical cross-links support mechanical properties of gel.

DOI： 10.1039/d4sm00628c

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Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

Cell behaviors are highly sensitive to the surrounding environment. Therefore, in regulating cells, biomaterial substrates should be designed so their properties are similar to the surrounding environments of the cells. For cell regulation, we designed dual stimuli-responsive gels whose physical (elastic modulus) and chemical (hydrophilicity) properties can be changed by varying the UV exposure time and temperature, respectively. A dual stimuli-responsive polymer with photodimerizable groups and temperature-responsive moieties was prepared by copolymerizing 7-methacryloyloxycoumarin (MAC) and methoxyoligoethylene glycol methacrylate (OEGMA). The resulting polymers (P(MAC-co-OEGMA)) had lower critical solution temperatures (LCSTs), which depended on the compositions. A buffer solution containing P(MAC-co-OEGMA) was exposed to ultraviolet light (UV) for gelation, and the elastic modulus increased with increasing exposure time. The cell behavior, including adhesion and spreading, on the surfaces of these gels was investigated. Most of the cells adhered to P(MAC-co-OEGMA) gels with higher elastic moduli, and the cells were spread more effectively at temperatures above the LCST. This was because cell adhesion and spreading were strongly influenced by the physical and chemical properties of the P(MAC-co-OEGMA) gels, which were regulated by varying the UV exposure time and temperature.

DOI： 10.1038/s41428-023-00865-7

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Other Link： https://www.nature.com/articles/s41428-023-00865-7

Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acs.macromol.3c01659

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acs.macromol.3c01049

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Publishing type：Research paper (scientific journal)   Publisher：Wiley  

Abstract

The regulation of cell behavior is crucial for understanding many fundamental biological processes and designing novel medical devices. Nano/micropatterning has been developed as a means of controlling cellular properties and behaviors. Using cinnamoyl groups that have undergone photodimerization, we have prepared facile photopatterning films with adjustable surface properties for cell patterning via simple steps. Our strategy for controlling surface properties uses the decrease in free volume induced by photocrosslinking. This paper describes the surface‐patterning properties of photocrosslinkable polymer films and the cell adhesion to their micropatterned surfaces. Upon culturing cells on micropatterned surfaces, preferential cell adhesion, alignment and proliferation are observed in the unexposed regions. Additionally, diverse surface patterns of photocrosslinkable polymer films have been fabricated using various photomasks, enabling effective control of cell adhesion and alignment. The ability to regulate cellular behavior via microfabricated surfaces of photocrosslinkable polymer films enables a new and facile approach for designing scaffolds for the development of novel advanced materials, tissue engineering, and regenerative medicine.

DOI： 10.1002/rpm.20230007

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Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

DLS measurements revealed that temperature-responsive gels prepared by ATRP have more homogeneous networks than those by free radical polymerization. The standard deviation of the scattered intensity is used to quantify the network inhomogeneity.

DOI： 10.1039/d3sm00044c

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Drug delivery systems (DDS) regulate the spatiotemporal distribution of drugs in vivo to maximize efficacy and minimize side effects. Stimuli-responsive hydrogels, which exhibit a drastic change in volume in response to external stimuli such as temperature and pH, have attracted considerable interest as drug reservoirs for self-regulating DDS, as stimuli-responsive changes in the network size can regulate drug diffusion. However, such hydrogels have the disadvantage of leaking drugs even in the absence of stimulation. Proteins such as hemoglobin have dynamic molecular binding sites that modify their binding capacities by their conformational changes induced when an effector molecule binds to allosteric sites. Such dynamic binding sites are useful for loading drugs into reservoirs because their conformational changes can be used to control drug loading and release. In this study, we prepared thermoresponsive hydrogels with a controlled drug binding capacity to design drug reservoirs capable of both suppressing drug leakage below the transition temperature and accelerating drug release above it. Dynamic molecular binding sites were created by molecular imprinting that used 4,4 '-diaminodiphenyl sulfone (dapsone) as the model drug, beta-cyclodextrin (CD) as the ligand, and N-isopropylacrylamide as the primary monomer. The molecularly imprinted (MIP) and nonimprinted (NIP) hydrogels with CD ligands, as well as the poly(N-isopropylacrylamide) (PNIPAAm) hydrogels without CD ligands, drastically shrunk above their transition temperature because of the PNIPAAm major chains changing conformation from a hydrophilic random coil to a hydrophobic globule as temperature increased. Because the MIP hydrogel has dynamic molecular binding sites, it absorbs a larger amount of dapsone than the NIP hydrogels in an aqueous solution below the transition temperature. The amount of dapsone adsorbed into the MIP hydrogel significantly decreased with increasing temperatures above 37 degrees C, despite the fact that the hydrophobic interaction between the polymer chains and dapsone became strong. The decrease in dapsone adsorption capability of the MIP hydrogel is due to a conformational change from a swollen to a shrunken state as temperature increases. The MIP hydrogel suppressed drug leakage below its transition temperature due to the high binding capacity of dynamic binding sites, but accelerated the drug release above its transition temperature due to the collapse of dynamic molecular binding sites, in contrast to the drug release behavior of general PNIPAAm-based hydrogels. Thus, the thermoresponsive MIP hydrogels with dynamic molecular binding sites regulated drug release in response to a change in temperature.

DOI： 10.1039/d2tb00325b

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Publishing type：Research paper (scientific journal)   Publisher：{MDPI} {AG}  

Standard hydrogels prepared by free radical polymerization (FRP) have heterogeneous structures with a wide mesh size distribution, which affect their mechanical and separation properties. Recent research has identified four-armed poly(ethylene glycol) (tetra-PEG) as a solution to this problem. tetra-PEG gels with a homogeneous network can be prepared and applied as high-strength gels and cell-culture substrates by reacting two types of tetra-PEG with different reactive groups at the ends. In this study, we report a photoresponsive tetra-PEG that undergoes a phase transition from a sol to a gel state in response to light. tetra-PEGs containing cinnamoyl and maleimide groups at the ends of the four-armed chains were found to gel when exposed to light. The effects of polymer concentration and light irradiation time on the gelation of tetra-PEG containing photodimerization groups were investigated. The results showed that the elastic modulus of the gel increased with the increase in the light irradiation time.

DOI： 10.3390/gels8030183

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Language：English   Publishing type：Research paper (scientific journal)  

Polymer particles with precise diameters have been used as building blocks for fabricating well-defined and nanostructured materials. Polymer particles as building blocks for medical applications require both easily spatiotemporal manipulation and good biocompatibility. In this study, we designed zwitterionic polymer particles with photodimerizable groups on their surfaces and used ultraviolet (UV) light irradiation to photo-assemble them in aqueous media. After synthesizing zwitterionic polymer particles with diameters ranging from 100-200 nm via soap-free emulsion polymerization, maleimide moieties as photodimerizable groups were introduced onto the particle surfaces. UV light irradiation to an aqueous dispersion of zwitterionic polymer particles with photodimerizable groups induced their photo-assembling because interparticle bonding forms by photodimerization of the photodimerizable groups on the particle surfaces. The zwitterionic surface of their particle-assembled films effectively suppressed protein adsorption, cell adhesion, and platelet adhesion. The photoresponsive behaviour and bioinert surface of the zwitterionic polymer particles with photodimerizable groups indicate that they have several potential applications as bioinert building blocks for designing well-defined and nanostructured biomaterials used in biosensors, bioseparation and cell culture, and for modifying and repairing biomaterial surfaces in situ.

DOI： 10.1039/d1tb02342j

PubMed

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY  

Photoresponsive polymers, whose structures or properties change when exposed to ultraviolet (UV) light, have been studied for the fabrication of micro- and nano-devices for various applications. Herein, photoresponsive polymer films are investigated with directly micropatternable surfaces formed by only UV exposure without the development process using solvents. The photoresponsive polymer films are designed based on the decrease in free volume induced by the photodimerization of cinnamoyl groups. The photoresponsive polymers are synthesized by copolymerizing a monomer with photodimerizable groups and a poly(dimethylsiloxane) macromonomer. Micropatterns are easily formed on the film surfaces by only UV exposure using photomasks. The micropatterns are achieved due to the decrease in the film thickness with a decrease in the free volume induced by photo-crosslinking. Using a decrease in free volume by photo-crosslinking leads to wide practical applications with simple processes and low costs.

DOI： 10.1002/admi.202101965

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acsami.2c00592

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

<title>Abstract</title>Hydrogels are flexible materials that have high potential for use in various applications due to their unique properties. However, their applications are greatly restricted by the low mechanical performance caused by high water content and inhomogeneous networks. This paper reports a universal strategy for easily preparing hydrogels that are tough and stretchable without any special structures or complicated processes. Our strategy involves tuning the polymerization conditions to form networks with many polymer chain entanglements to achieve energy dissipation. Tough and stretchable hydrogels can be prepared by free radical polymerization with a high monomer concentration and low cross-linker content to optimize the balance between physical and chemical cross-links by entanglements and covalent bonds, respectively. The strategy of using polymer chain entanglements for energy dissipation allows us to overcome the limitation of low mechanical performance, which leads to the wide practical use of hydrogels.

DOI： 10.1038/s41427-021-00302-2

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Other Link： http://www.nature.com/articles/s41427-021-00302-2

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.memsci.2019.117213

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Nature Publishing Group  

Molecularly imprinted hydrogel layers with lectin-recognition sites were prepared on surface plasmon resonance (SPR) sensor chips via surface-initiated atom transfer radical polymerization (SI-ATRP) combined with molecular imprinting. The lectin-imprinted hydrogel layer sensor chips showed larger SPR signal change in response to a target lectin than nonimprinted hydrogel layer sensor chips. The larger SPR signal change was attributed to the strong affinity constant of the lectin-imprinted hydrogel layer for the target lectin. These results suggest that molecular recognition sites for the lectin were formed within the hydrogel layers by molecular imprinting. On the other hand, the SPR signal change of the lectin-imprinted hydrogel layer chip in the presence of other lectin was very small. Poly(2-methacryloxyethyl phosphorylcholine) as a main chain of the hydrogel layer inhibited nonspecific adsorption of other lectin. This paper describes that SI-ATRP with biomolecular imprinting is a useful method to design highly sensitive and selective SPR sensor chips with molecular recognition sites for a target lectin.

DOI： 10.1038/s41428-017-0013-7

Scopus

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Stimuli-responsive polymers that undergo a sol-gel transition in response to changes in environmental factors such as pH and temperature have attracted considerable attention for biomedical applications such as drug reservoirs for controlled release and scaffolds for tissue engineering. Although numerous stimuli-responsive polymers that undergo a sol-gel transition have been reported, the literature contains few accounts of biomolecularly stimuli-responsive polymers that undergo a sol-gel transition in response to a specific biomolecule. In previous studies, we designed biomolecule-responsive hydrogels that undergo changes in volume in response to a target biomolecule; the strategy involves using biomolecular complexes as dynamic cross-links in the gel networks. In the present study, we designed biotin-conjugated four-armed poly(ethylene glycol) (biotinylated Tetra-PEG) as biomolecular stimuli-responsive sol-gel transition polymers that underwent the phase transition from a sol to a gel state in response to avidin as a target biomolecule. When avidin that forms a biomolecular complex with biotin was added to a buffer solution containing biotinylated Tetra-PEG, the solution transformed to a gel state immediately. However, the addition of a buffer solution with free biotin to the resulting hydrogel induced its dissociation to a sol state. The sol-gel transition of a buffer solution with biotinylated Tetra-PEG was directly affected by polymer concentration and the biotin/avidin molar ratio. The phase diagram of the sol-gel transition of biotinylated Tetra-PEG in a buffer solution as a function of polymer concentration and the biotin/avidin molar ratio is presented.

DOI： 10.1039/c7py01370a

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm) gels were prepared via atom transfer radical polymerization (ATRP), and their mechanical and responsive properties were investigated from the viewpoint of their network homogeneity. When the PNIPAAm gels were prepared by ATRP and free radical polymerization (FRP) at a low temperature, no difference was observed in the mechanical properties. However, the PNIPAAm gels prepared via ATRP at room temperature showed a higher elastic modulus and greater temperature-responsive change than the gels prepared via FRP. The temperature-responsive shrinkage rate of the PNIPAAm gel prepared via ATRP was slower than that of the gel prepared via FRP. Dynamic light scattering (DLS) measurements revealed that these results can be attributed to the more homogeneous network structure in the PNIPAAm gel prepared via ATRP than in the gel prepared via FRP.

DOI： 10.1039/c7py01323j

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Polypeptides have inherent secondary structures, such as alpha-helix,) beta-sheet, and random coil structures, depending on their amino acid sequence. beta-Cyclodextrins (CDs) as ligands of molecular recognition sites were introduced into poly(Llysine) (PLL), which undergoes a structural transition in response to a pH change. CD-introduced PLL (CD-PLL) hydrogels with dynamic molecular recognition sites for bisphenol A (BPA) were strategically designed by molecular imprinting, where BPA was used as a template molecule with a minute amount of cross-linkers. The resulting BPA-imprinted CD-PLL hydrogels with a random coil structure underwent a change in volume in response to the target BPA because the ligand CDs formed a complex with BPA. Additionally, a change in pH induced a structural transition of the CD-PLL chains from the random coil to an a-helix, followed by a conformational change of the molecular recognition sites within the BPA-imprinted CD-PLL hydrogels. As a result, BPA adsorption into the BPA-imprinted CD-PLL hydrogels strongly depended on pH. The molecular recognition ability of the BPA-imprinted CD-PLL hydrogels was controlled by the helix coil transition of the PLL chains. BPA, as a model drug, was loaded within the CD-PLL hydrogel networks by molecular imprinting, and the BPA template was not extracted from the hydrogel networks. The drug release from the drug-loaded CD-PLL hydrogel was regulated by the pH-responsive structural transition of the PLL chains, which could control the stability of the inclusion complex between the drugs and CD ligands. The fascinating properties of the BPA-imprinted CD-PLL hydrogels with dynamic molecular recognition sites suggest that they exhibit potential as suitable drug carriers inspired from the allosteric effects of proteins.

DOI： 10.1021/acs.macromol.6b02688

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Molecular imprinting is a well-known fabrication technique for designing artificial receptors and molecular sensors. The technique resembles a lock and key mechanism and utilizes shape-complementary cavities within polymeric materials as molecular recognition sites for various relevant molecules. In this study, we prepared molecularly imprinted polypeptide gel layers based on cyclodextrin-modified poly(L-lysine) (CD-PLL) on quartz crystal microbalance (QCM) sensor chips and investigated their molecular recognition behaviors for bisphenol A (BPA) using the QCM technique. With BPA as the template and CD as its ligand, the BPA-imprinted CD-PLL gel layers were prepared on electropolymerized polyterthiophene films, which were formed using electrochemical QCM (EQCM). The BPA-imprinted CD-PLL gel layer chip exhibited a much greater QCM response than the non-imprinted gel layer chip in an aqueous BPA solution. The greater response of the BPA-imprinted CD-PLL gel layer chip means that molecular imprinting enabled CD ligands to be arranged at optimal positions for forming molecular recognition sites. The combination of in situ electropolymerization using EQCM and molecular imprinting provides useful methods for fabricating highly selective and sensitive sensor devices for monitoring minute amounts of BPA in water.

DOI： 10.1038/pj.2016.23

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Walter de Gruyter {GmbH}  

DOI： 10.1515/molim-2016-0003

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Poly(L-lysine) (PLL) undergoes structural change from alpha-helix to random coil in response to a change in pH in an aqueous solution. By chemical crosslinking of PLL with ethylene glycol diglycidyl ether (EGDE), we prepared pH-responsive hydrogels that undergo a change in volume and conformation between a-helix and random coil in response to a change in pH. The difference in transition pH between a PLL linear polymer and a PLL hydrogel revealed that chemical crosslinking stabilized the helical structure of PLL chains in hydrogel networks.

DOI： 10.1246/cl.150464

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Microdevices designed for practical environmental pollution monitoring need to detect specific pollutants such as dioxins. Bisphenol A (BPA) has been widely used as a monomer for the synthesis of polycarbonate and epoxy resins. However, the recent discovery of its high potential ability to disrupt human endocrine systems has made the development of smart systems and microdevices for its detection and removal necessary. Molecule-responsive microsized hydrogels with -cycrodextrin (-CD) as ligands are prepared by photopolymerization using a fluorescence microscope. The molecule-responsive micro-hydrogels show ultra-quick shrinkage in response to target BPA. Furthermore, the flow rate of a microchannel is autonomously regulated by the molecule-responsive shrinking of their hydrogels as smart microvalves.

DOI： 10.1002/marc.201400676

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Novel organic-inorganic hybrid nanoparticles with a bisphenol A (BPA)-responsive hydrogel layer on the surface of SiO2 nanoparticles were prepared via surface-initiated atom transfer radical polymerization of acrylamide (AAm), acryloyl-modified beta-cyclodextrin (CD) and N, N'-methylenebisacrylamide. The resulting CD-PAAm/SiO2 nanoparticles underwent a change in size in response to BPA. The BPA-responsive shrinkage of the CD-PAAm/SiO2 nanoparticles was caused by an increase in the crosslinking density of the CD-PAAm hydrogel layer, which resulted from the formation of CD-BPA-CD complexes acting as dynamic crosslinks. The smart functions of BPA-responsive organic-inorganic hybrid nanoparticles can provide useful tools for constructing molecular sensors and adsorption materials.

DOI： 10.1038/pj.2014.122

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

We prepared lectin-imprinted hydrogel layers on surface plasmon resonance (SPR) sensor chips by atom transfer radical polymerization (ATRP). In a buffer solution with a target protein, the SPR signal and binding constant of the lectin-imprinted hydrogel layer chip were much larger than those of the nonimprinted hydrogel layer chip prepared without using a template lectin. By molecular imprinting with ATRP, recognition sites for the target lectin were formed within thin hydrogel layers on the SPR sensor chips. The lectin-imprinted hydrogel layer chips with recognition sites for target protein are candidates for highly sensitive sensor devices for an SPR sensing system.

DOI： 10.1246/cl.140103

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Target molecule-responsive hydrogels with beta-cyclodextrin (beta-CD) were prepared via molecular imprinting using bisphenol A (BPA) as a template. BPA-imprinted hydrogels showed greater shrinkage than non-imprinted hydrogels because CD ligands arranged at suitable positions formed CD-BPA-CD complexes that acted as crosslinks.

DOI： 10.1039/c4cc01187b

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

We prepared antibody-immobilized gel layers on surface plasmon resonance (SPR) sensor chips by atom transfer radical polymerization (ATRP). In a buffer solution with a target antigen, the SPR signal of the antibody-immobilized gel layer chip with an optimal thickness was much larger than that of a directly antibody-immobilized chip prepared by the standard amine coupling method. The antibody-immobilized gel layer chips are candidates as highly sensitive bioconjugated devices for SPR sensing systems. This paper focuses on the relationship between the thickness of the gel layer and the SPR signal in the detection of a target antigen.

DOI： 10.1246/cl.2012.1660

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Bioconjugated gel particles that have complexes composed of lectin concanavalin A (ConA) and 2-glucosyloxyethyl methacrylate (GEMA) were synthesized by the surfactant-free emulsion copolymerization of N,N-diethylaminoethyl methacrylate (DEAEMA), poly(ethylene glycol) dimethacrylate (PEGDMA). GEMA, and modified-ConA with polymerizable groups. The resultant gel particles having GEMA-ConA complexes (GEMA-ConA gel particles) were colloidally stable in a phosphate buffer solution and had a diameter of approximately 750 nm. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements implied that GEMA-ConA gel particles have core-shell structures consisting of a hydrophobic core of DEAEMA and a hydrophilic shell of GEMA and PEGDMA containing ConA. GEMA-ConA gel particles underwent a change in size in response to glucose in a phosphate buffer solution. The swelling ratio of GEMA-ConA gel particles gradually increased with an increase in the glucose concentration. On the other hand, the swelling ratio of GEMA-ConA gel particles remained unchanged in a phosphate buffer solution containing galactose. The glucose-responsive swelling of GEMA-ConA gel particles was induced by the dissociation of GEMA-ConA complexes acting as reversible cross-links, because free glucose behaved as an inhibitor of GEMA-ConA complexes. These results indicate that GEMA-ConA gel particles can recognize glucose selectively and undergo changes in size in response to the glucose concentration. The smart functions of glucose-responsive gel particles can provide tools for constructing self-regulated drug delivery systems and sensor systems useful for treating diabetes. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.colsurfb.2011.10.008

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

A novel nucleobase-terminated organosilane with nucleobase and ethoxysilane moieties was synthesized by a simple method in which bromouracil reacts with amino-terminated organosilane without solvents. The uracil-terminated organosilane was self-assembled on a hydroxylated surface, and then the uracil-concentrated surface was obtained. The resulting uracil-terminated self-assembled layers were characterized by X-ray photoelectron spectroscopy and ellipsometry. Adenine complementary to uracil was effectively adsorbed onto the resultant uracil-concentrated surface by multiple hydrogen bonds. Herein, a simple method is provided for synthesizing a nucleobase-terminated organosilane and modifying a hydroxylated surface to a nucleobase-concentrated surface. Our method, which uses the self-assembly of nucleobase-terminated organosilanes, facilitates the construction of bioconjugated devices for separating and sensing nucleobases and nucleic acids. Polymer Journal (2012) 44, 625-631; doi:10.1038/pj.2012.41; published online 28 March 2012

DOI： 10.1038/pj.2012.41

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：VSP BV  

Egg white lysozyme was chemically modified by PEGylated PAMAM 1st, 2nd and 3rd generation dendrons, which had 2, 4 and 8 PEG arms, respectively. The number of PEG chains introduced to the lysozyme molecule drastically increased with an increase in dendron generation, although the number of PEGylated PAMAM dendrons introduced decreased due to steric repulsion. The lytic activity of lysozyme to Micrococcus luteus cells was effectively inhibited by conjugating PEGylated PAMAM dendron to the lysozyme, indicating steric stabilization of PEG chains at the surface of lysozyme molecule. In addition, the enzymatic reaction of the lysozyme with oligosaccharide substrate was apparently accelerated by a substrate condensation effect due to the multi-armed structure of PEG. (C) Koninklijke Brill NV, Leiden, 2011

DOI： 10.1163/092050610X514557

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS INC  

The comb-type polyelectrolyte, poly(ethylene glycol)-graft-poly(allyl amine) (PEG-g-PAA), was synthesized to prepare polyion complex (PIC) micelles with Aspergillus Niger Glucose oxidase (GOD). Even after mixing GOD and PEG-g-PAAs with various PEG contents, the resulting mixtures remained transparent but the mixture of GOD and PAA homopolymer immediately precipitated. In the mixtures prepared with a stoichiometric mixing ratio, the formation of PIC micelles with a core-shell structure was suggested from dynamic and static light scattering measurements. Glucose, the substrate for GOD, could easily diffuse into the PIC micelles, and the GOD molecules were active even in the core of the PIC micelles. GOD didn&apos;t lose its enzymatic activity through entrapment into the PIC micelles. (C) 2008 Wiley Periodicals, Inc.

DOI： 10.1002/pola.22739

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS INC  

Poly(N-isopropylacrylamide) (PNIPAAm) gels are temperature-responsive polymer gels; and were prepared by redox polymerization of N-isopropylacrylamide in the presence of N,N&apos;-methylenebisacrylamide as a crosslinking reagent and core-shell type bioconjugates, which were core-crosslinked polyion complex micelles formed from the mixture of bovine pancreas trypsin and poly(ethylene glycol)-block-poly(alpha,beta-aspartic acid). The phase transition temperature of PNIPAAm gels was no change with physically immobilization of bioconjugates. Also, the enzymatic activity of bioconjugates was essentially maintained even in PNIPAAm gels, although enzymatic reaction rate was apparently controlled by temperature, i.e., by the degree of swelling of PNIPAAm gels. Further, the control of enzymatic reaction synchronizing the phase transition of PNIPAAm gels immobilized bioconjugates. PNIPAAm gels could immobilize core-shell type bioconjugates, and were successfully prepared without interfering with the properties of temperature-responsive polymer gels and the bionanoreactor. (c) 2007 Wiley Periodicals, Inc.

DOI： 10.1002/pola.22347

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Core-cross-linked polyion complex (PIC) micelles entrapping trypsin in the core were prepared by mixing trypsin and poly(ethylene glycol)-block-poly(alpha,beta-aspartic acid) in aqueous medium, followed by the introduction of glutaraldehyde cross-linkages. Trypsin incorporated into the core-cross-linked micelles showed high storage stabilities, and the initial enzymatic activity of trypsin was maintained even after standing for one week at ambient temperature. Further, stable compartmentalization of trypsin into the core-cross-linked micelles led to a unique modulation in the enzymatic functions including an improved thermal tolerability with an increased maximum reaction rate compared to native trypsin.

DOI： 10.1021/bc070029t

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

The amidase reaction of trypsin, which is a member of the serine proteinase family, is accelerated by its complexation with block ionomers containing a polycarboxylate block, such as PEG-PAA, PEG-PGA, or PEG-PMA. PEG-PAA and PEG-PGA had similar effects, causing an increase in the k(cat) value and a shift in the pH profile to a lower pH region. On the other hand, PEG-PAAA showed not only an increase in the kcat value, but also a decrease in the activation energy; however, there was no shift in the pH dependence of the initial reaction rate. Such differences might be induced by the difference in pK(a) values of the polycarboxylate block in block ionomers.

DOI： 10.1002/mabi.200600199

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The amidase activity of bovine pancreas trypsin in water-soluble complexes with poly(ethylene glycol)block-poly(alpha,beta-aspartic acid) (PEG-PAA) was evaluated by a colorimetric assay using L-lysine p-nitroanilide as a substrate. The enzymatic reaction of trypsin was accelerated through the complexation with PEG-PAA. By determining the kinetic parameters of the enzymatic reaction of trypsin, it was confirmed that the catalytic rate constant of the complexed trypsin was 15 times higher than that of the native trypsin. From the evaluation of pH dependence of initial reaction rate, it was indicated that this acceleration was induced by a stabilization of the imidazolium ion of the His residue in the catalytic site, the Asp-His-Ser triad, of trypsin due to the Asp units of PEG-PAA. The hydrogen bonded Asp-His pairs are critical constituents in several key enzymatic reactions including serine protease and apurinic endonucleases, and it was expected that the acceleration of the catalytic reaction might occur for other enzymes by the formation of water-soluble complexes with PEG-PAA.

DOI： 10.1021/bm049198w

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Event date： 2015.8

Venue：Sun Moon Lake, Taiwan  

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Event date： 2014.11

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Event date： 2014.11

Venue：The Korea Science and Technology Center, Seoul, Korea  

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Venue：Web開催  

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Venue：Web開催  

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Applicant：日油株式会社

Application no：特願2015-142393  Date applied：2015.7

Announcement no：特開2017-023902  Date announced：2017.2

Patent/Registration no：特許第6485263号  Date registered：2019.3 

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Applicant：学校法人 関西大学

Application no：2014-148499  Date applied：2014.7

Announcement no：2016-23243  Date announced：2016.2

Patent/Registration no：特許第6558621号  Date registered：2019.7 

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Applicant：学校法人 関西大学

Application no：2014-039966  Date applied：2014.2

Announcement no：2015-164978  Date announced：2015.9

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Applicant：大塚化学株式会社, 学校法人 関西大学

Application no：2013-138964  Date applied：2013.7

Announcement no：2015-010219  Date announced：2015.1

Patent/Registration no：特許第6108990号  Date registered：2017.3 

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Applicant：学校法人 関西大学

Application no：2012-256965  Date applied：2012.11

Announcement no：2014-103857  Date announced：2014.6

Patent/Registration no：特許第6070106号  Date registered：2017.1 

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Applicant：公立大学法人大阪府立大学

Application no：2005-235669  Date applied：2005.8

Announcement no：2007-51182  Date announced：2007.3

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