Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier B.V.  

In general, chitosan (CS) cannot be dissolved in basic solution, however it was found that the basic CS solution could be prepared using sodium hydrogen carbonate. NMR measurements revealed that CS was transformed to carbamate ion in the basic condition (around pH 8) thus it acts as anionic nature in this medium. Based on this discovery, novel polyelectrolyte complex (PEC) gel of sodium alginate (SA) and CS was successfully prepared using a basic CS solution and D-gluconolactone (GDL). Gel formation mechanism was explained based on the 1 H and 13 C NMR measurement results. It was found that the elastic modulus of SA/CS PEC gel were higher than that of SA/Chitosan oligomer gel. Moreover, the SA/CS PEC gel was the homogeneous gel and become over 7000 Pa for maximum of elastic modulus. This novel PEC gel will be used in several applications such as tissue engineering, drug delivery system and fuel cell.

DOI： 10.1016/j.ijbiomac.2018.12.195

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DOI： 10.3390/polym11030466

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

A novel nanofibrous gel electrolyte was prepared via gelatin electrospinning for use as a nonaqueous electrolyte in electric double-layer capacitors (EDLCs). An electrospinning technique with a 25 wt% gelatin solution was applied to produce gelatin electrospun (GES) nanofiber electrolytes. Structural analysis of the GES products showed a clearly nanofibrous structure with fiber diameters in the 306.2-428.4 nm range and exhibiting high thermal stability, high tensile strength, and a stable form of nanofibrous structure after immersion in 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4). After testing over a range of spinning times, GES electrolytes that were produced at 25 min (GES-25) had a suitable thickness for the assembly of EDLC with the optimized tensile properties and were used to fabricate EDLC test cells with EMImBF4. These test cells were compared to those with pure EMImBF4 and a separator as an electrolyte. The electrochemical properties of the test cells were characterized by charge-discharge testing, discharge capacitance, and alternative current (AC) impedance measurements. AC impedance measurements showed that the test cell with the GES-25/EMImBF4 gel electrolyte showed slightly poorer contact with the electrode when compared to that with pure EMImBF4, whereas exhibited comparable IR drop and discharge capacitance (calculated capacitance retention was 56.6%). The results demonstrated that this novel gel electrolyte can be used as a nonaqueous electrolyte in order to improve the safety in EDLCs.

DOI： 10.1155/2019/2501039

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DOI： 10.1016/j.ijbiomac.2018.12.006

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DOI： 10.1021/acs.jpcc.8b02373

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DOI： 10.1007/s11164-018-3348-6

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

The increase of the stability of chitosan (CS) in the solution is extremely important for the application of CS in various fields. In this study, we describe that the hydrogelation of CS can solve this problem. CS hydrogel was readily prepared by addition of a sodium hydroxide solution to a CS acetic acid solution. The CS hydrogel was stable in the wet state and could maintain its molecular weight for a long period of time at room temperature. The obtained CS hydrogel could be readily dissolved with addition of acids, such as acetic acid and other organic acids, as determined by measuring the pH and transmittance of the solutions. Dissolution of the CS hydrogel indicated that the amount of carboxylate ion per amino group of CS was only 0.5 molar equivalents. Moreover, the binding state between the acetic acid and amino groups of CS in an aqueous solution is discussed using results from H-1 NMR spectroscopy. The methyl signals attributed to free acetic acid, acetic acid in an ionic bond, and the acetamido group of the N-acetylglucosamine residue were clearly observed, and the strength of each peak changed quantitatively with the addition of acetic acid. (C) 2017 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ijbiomac.2017.02.099

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Rayon fiber coated with chitosan (CTS) that contained immobilized Prussian blue (KFe) (KFe/CTS/rayon) were investigated for the removal of cesium ion (Cs') from contaminated water. The morphology and mechanical strength of the fibers were observed using scanning electron microscopy (SEM) and a universal testing machine, respectively. The Cs' concentration was determined by inductively coupled plasma-atomic emission spectroscopy. SEM images revealed that the surface of the KFe/CTS/rayon fiber showed the most roughness. It was found that Cs+ was absorbed from the water by the KFe on the fibers in a molar ratio of 1:1 (Cs+:KFe). After treating the KFe/CTS/rayon fiber with 1% HNO3 for 3 h, 48.8% Cs+ desorption was observed. Woven fibers were interlaced with either 2 or 4 lines of the KFe/CTS/rayon fiber from 16 bobbins. The tensile strengths of those fibers were 19.06 and 14.25 MPa, respectively. When silver cotton was used as the core axis of the woven fiber, the tensile strength of the fibers interlaced with 2 and 4 lines increased to 27.18 and 25.17 MPa, respectively. Moreover, the results of hot tests using radioactive Cs+ showed that the woven KFe/CTS/rayon fibers could absorb up to 1000 Bq g(-1) from an initial concentration of 8000 Bq kg(-1). (C) 2017 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ijbiomac.2017.03.056

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

Skin loss is one of the oldest and still not totally resolved problems in the medical field. Since spontaneous healing of the dermal defects would not occur, the regeneration of full thickness of skin requires skin substitutes. Tissue engineering constructs would provide a three dimensional matrix for the reconstruction of skin tissue and the repair of damage. The aim of the present work is to develop a chitin based scaffold, by blending it with poly(butylene succinate) (PBS), an aliphatic, biodegradable and biocompatible synthetic polymer with excellent mechanical properties. The presence of chondroitin sulfate nanoparticles (CSnp) in the scaffold would favor cell adhesion. A chitin/PBS/CSnp composite hydrogel scaffold was developed and characterized by SEM (Scanning Electron Microscope), FTIR (Fourier Transform Infrared Spectroscopy), and swelling ratio of scaffolds were analyzed. The scaffolds were evaluated for the suitability for skin tissue engineering application by cytotoxicity, cell attachment, and cell proliferation studies using human dermal fibroblasts (HDF). The cytotoxicity and cell proliferation studies using HDF confirm the suitability of the scaffold for skin regeneration. In short, these results show promising applicability of the developed chitin/PBS/CSnps ternary composite hydrogel scaffolds for skin tissue regeneration.

DOI： 10.3390/polym6122974

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Language：English   Publishing type：Part of collection (book)   Publisher：Academic Press Inc.  

Nowadays, chitin and chitosan are produced from the shells of crabs and shrimps, and bone plate of squid in laboratory to industrial scale. Production of chitosan involved deproteinization, demineralization, and deacetylation. The characteristics of chitin and chitosan mainly depend on production processes and conditions. The characteristics of these biopolymers such as appearance of polymer, turbidity of polymer solution, degree of deacetylation, and molecular weight are of major importance on applications of these polymers. This chapter addresses the production processes and conditions to produce chitin, chitosan, and chito-oligosaccharide and methods for characterization of chitin, chitosan, and chito-oligosaccharide. © 2014 Elsevier Inc.

DOI： 10.1016/B978-0-12-800269-8.00001-4

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

Novel water-dispersible, pH-stable, and biocompatible quantum dots were synthesized through the surface modification of silicon quantum dots (SiQDs) with monosaccharides. The presence of the monosaccharide on the surface of the SiQDs was recognized by fluorescence measurements using its complementary lectin (concanavalin A). The fluorescence cell imaging was carried out by using SiQDs functionalized chemically with D-glucosamine, and it was shown that the SiQDs developed in this study are applicable as blue chromophores for biological fluorescence imaging.

DOI： 10.1246/cl.130068

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

Chitin and its derivatives have been widely used in drug delivery applications due to its biocompatible, biodegradable and non-toxic nature. In this study, we have developed amorphous chitin nanoparticles (150 +/- 50 nm) and evaluated its potential as a drug delivery system. Paclitaxel (PTX), a major chemotherapeutic agent was loaded into amorphous chitin nanoparticles (AC NPs) through ionic cross-linking reaction using TPP. The prepared PTX loaded AC NPs had an average diameter of 200 +/- 50 nm. Physicochemical characterization of the prepared nanoparticles was carried out. These nanoparticles were proven to be hemocompatible and in vitro drug release studies showed a sustained release of PTX. Cellular internalization of the NPs was confirmed by fluorescent microscopy as well as by flow cytometry. Anticancer activity studies proved the toxicity of PTX-AC NPs toward colon cancer cells. These preliminary results indicate the potential of PTX-AC NPs in colon cancer drug delivery. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.colsurfb.2012.11.031

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Language：English   Publishing type：Part of collection (book)   Publisher：CRC Press  

Natural biopolymers such as gelatin, agar, agarose, alginate, carrageen, chitin, and chitosan can be produced from marine materials (e.g., gelatin is obtained from fish skin, pork skin, cattle bones, etc
alginates are obtained from seaweed
chitin and chitosan are obtained from shells of shrimps, crabs, and lobsters and bone plates of squids, crayfishes, krill, and cuttlefishes). Among them, chitin and chitosan have been used in various products such as antioxidative agents, bone-healing agent, cholesterol reduction agent, dental enamel de-remineralization, edible film, flocculating agent, growth stimulating agent for plant, hemostatic agent, immune stimulating agent, immobilization of cell, and juice clarification (Nwe et al. 2011).

DOI： 10.1201/b14723

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

Nylon felts used in the paper manufacturing process are constructed of Nylon-6 and Nylon-6,6 and most of the 1100 t/year of felt produced is disposed of. In this study, a new process was proposed for regeneration of Nylon-6 and Nylon-6,6 from Nylon felts discarded by the paper mill industry. The process consists of dissolution-separation of Nylon into a solvent, reprecipitation of Nylon using a non-solvent, and recycling of waste solvent from the above two steps by distillation. The mixed solution of methanol with calcium chloride dihydrate (CaCl2-MeOH solution) used in the previous work was again used as solvent for dissolution of Nylons. The experimental results on the selective separation of Nylon-6 or Nylon-6,6 showed that both were possible by adjusting the concentration of calcium chloride dihydrate in the solvent. The results of X-ray diffraction analysis suggested that the solubility of Nylons was affected by their crystalline structures. The experimental results on solvent recovery indicated that methanol, water and calcium chloride dihydrate could be recycled by double distillation. By the proposed process, Nylons were regenerated in a high recovery rate 92.8% from felt wastes, and the purities of Nylon-6 and Nylon-6,6 were almost 100% and 81.4% respectively. This process is thus considered applicable for regeneration of Nylon-6 and Nylon-6,6 from Nylon wastes in chemical industries.

DOI： 10.1252/kakoronbunshu.39.238

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Language：English   Publisher：MDPI AG  

Tissue engineering/regeneration is based on the hypothesis that healthy stem/progenitor cells either recruited or delivered to an injured site, can eventually regenerate lost or damaged tissue. Most of the researchers working in tissue engineering and regenerative technology attempt to create tissue replacements by culturing cells onto synthetic porous three-dimensional polymeric scaffolds, which is currently regarded as an ideal approach to enhance functional tissue regeneration by creating and maintaining channels that facilitate progenitor cell migration, proliferation and differentiation. The requirements that must be satisfied by such scaffolds include providing a space with the proper size, shape and porosity for tissue development and permitting cells from the surrounding tissue to migrate into the matrix. Recently, chitin scaffolds have been widely used in tissue engineering due to their non-toxic, biodegradable and biocompatible nature. The advantage of chitin as a tissue engineering biomaterial lies in that it can be easily processed into gel and scaffold forms for a variety of biomedical applications. Moreover, chitin has been shown to enhance some biological activities such as immunological, antibacterial, drug delivery and have been shown to promote better healing at a faster rate and exhibit greater compatibility with humans. This review provides an overview of the current status of tissue engineering/regenerative medicine research using chitin scaffolds for bone, cartilage and wound healing applications. We also outline the key challenges in this field and the most likely directions for future development and we hope that this review will be helpful to the researchers working in the field of tissue engineering and regenerative medicine.

DOI： 10.3390/ijms12031876

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Chitin is a non-toxic, biodegradable and biocompatible natural polymer. It is used in several biomedical applications. Chitin is insoluble in most of the organic solvents due to its rigid crystalline structure. However, it can be dissolved in calcium chloride dehydrate methanol (Ca solvent) solvent system. The alpha- and beta-chitin hydrogels can easily be developed using the Ca solvent system. Using these hydrogels, it is able to develop scaffolds and membranes for the variety of biomedical applications such as tissue engineering and wound dressing. In this paper, we present the preparation and biomedical applications of chitin hydrogel membranes and scaffolds. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.carbpol.2010.06.001

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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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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Material selection in tissue-engineering scaffolds is one of the primary factors defining cellular response and matrix formation. In this study, we fabricated chitosan-coated poly(lactic acid) (PLA) fiber scaffolds to test our hypothesis that PLA fibers coated with chitosan highly promoted cell supporting properties compared to those without chitosan. Both PLA fibers (PLA group) and chitosan-coated PLA fibers (PLA-chitosan group) were fabricated for this study. Anterior cruciate ligament (ACL) fibroblasts were isolated from Japanese white rabbits and cultured on scaffolds consisting of each type of fiber. The effects of cell adhesivity, proliferation, and synthesis of the extracellular matrix (ECM) for each fiber were analyzed by cell counting, hydroxyproline assay, scanning electron microscopy and quantitative RT-PCR. Cell adhesivity, proliferation, hydroxyproline content and the expression of type-I collagen mRNA were significantly higher in the PLA-chitosan group than in the PLA group. Scanning electron microscopic observation showed that fibroblasts proliferated with a high level of ECM synthesis around the cells. Chitosan coating improved ACL fibroblast adhesion and proliferation, and had a positive effect on matrix production. Thus, the advantages of chitosan-coated PLA fibers show them to be a suitable biomaterial for ACL tissue-engineering scaffolds. (C) Koninklijke Brill NV, Leiden, 2011

DOI： 10.1163/092050610X491067

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

A process for separation and recycling of Nylon-6,6 from air-bags made of Nylon-6,6 cloth coated with silicon resin (SCAB) was examined. In this study, a mixed solution of calcium chloride dehydrate and methanol (CaCl(2)-MeOH), which is known to be a good solvent for chitin, was used as solvent for separation and recycling of Nylon-6,6. SCAB was immersed with stirring SCAB in CaCl(2)-MeOH solution, whereby Nylon-6,6 was dissolved and silicon resin was separated as residue. Distilled water was then added to the filtrate, Nylon-6,6 was precipitated with purity of 99% or more and in a yield of more than 97%. It was confirmed that CaCl(2) separated from waste fluid after recovery of Nylon-6,6 was reusable as CaCl(2)-MeOH solution. Infrared spectroscopic analysis of Nylon-6,6 in CaCl(2)-MeOH solution also confirmed that the deformation vibration peak of the N-H group and the stretching vibration peak of the C-N bond were shifted to higher wave number. These changes are considered to be due to weakening or breaking of hydrogen bonding between Nylon-6,6 molecules. In view of this, Nylon-6,6 seems to be dissoluble in CaCl(2)-MeOH solution. Because the proposed process is a safer than one using inorganic acids or phenols as solvent, it is expected to be useful for separation and recycling of Nylon-6,6 from waste.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Poly(lactic acid) (PLA)/chitosan (CS) nanoparticles were prepared by emulsion method for anti-HIV drug delivery applications. The prepared PLA/CS nanoparticles were characterized using DLS, SEM, and FTIR. The hydrophilic antiretroviral drug Lamivudine was loaded into PLA/CS nanoparticles. The encapsulation efficiency and in-vitro drug release behaviour of drug loaded PLA/CS nanoparticles were studied using UV spectrophotometer. In addition, the cytotoxicity of the PLA/CS nanoparticles using MTT assay was also studied. The in-vitro drug release studies showed that drug release rate was lower in the acidic pH when compared to alkaline pH. This may due to repulsion between H ions and cationic groups present in the polymeric nanoparticles. Drug release rate was found to be higher in the 6% drug loaded formulation when compared to 6% drug loaded formulation. These results indicated that the PLA/CS nanoparticles are a promising carrier system for controlled delivery of anti-HIV drugs. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.carbpol.2009.12.040

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Chitosan is a novel biocompatible, biodegradable polymer for potential use in tissue engineering. In this work, chitosan-gelatin/nanophase hydroxyapatite composite scaffolds were prepared by blending chitosan and gelatin with nanophase hydroxyapatite (nHA). The prepared nHA was characterized using TEM, XRD and FT-IR. The prepared composite scaffolds were characterized using SEM, FT-IR and XRD studies. The composite scaffolds were highly porous with a pore size of 150-300 mu m. In addition, density, swelling ratio, degradation, biomineralization, cytotoxicity and cell attachment of the composite scaffolds were studied. The scaffolds showed good swelling character, which could be modulated by varying ratio of chitosan and gelatin. Composite scaffolds in the presence of nHA showed a decreased degradation rate and increased mineralization in SBF. The biological response of MG-63 cells on nanocomposite scaffolds was superior in terms of improved cell attachment, higher proliferation, and spreading compared to chitosan-gelatin (CG) scaffold. (C) 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.carbpol.2009.11.050

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Material selection is one of the most important aspects to construct a novel template for tissue regeneration. In this research alginate, bacterial cellulose (BC) and gelatin were selected based on available material and published data to prepare membranes and then the morphology of Swiss mouse embryo fibroblast NIH/3T3 cells on the surface of these membranes was examined to select the best material for the development of a biodegradable skin tissue regeneration template. The cells on alginate membrane crosslinked with Ca2+ (AGM_Ca) showed a spherical morphology and growth retardation, probably due to high calcium content on and in the surface of membrane. This has been confirmed in control experiments in which calcium was added to the culture medium (DMEM medium). The NIH/3T3 cells grown on the BC membrane (BC_M) and membrane of glutaraldehyde (GTA) crosslinked gelatin (GTA_GM) had a polygonal morphology. The proliferation rate of cells on the GTA_GM was faster than that on the BC_M. Therefore the GTA_GM is better than the AGM_Ca and BC_M to apply as a skin tissue regeneration template. Cytotoxic effects of GTA were studied in GTA_GMs prepared using gelatins obtained from cow bones, pork skins, and fish skins. It was found that molar ratio of GTA to gelatin for preparation of membrane should not be higher than 0.033. Cytotoxic effects of CIA were observed on the GTA_GMs prepared with molar ratio higher than 0.033, except pork skin gelatin membrane with a molar ratio, 0.033, which showed the cytotoxic effects on fibroblast cells. The physical morphology of the membranes of cow bone gelatin and fish skin gelatin is stronger and more flexible than that of pork skin gelatin in wet forms. According to these results, it can be suggested that pork skin gelatin might have had less crosslinked points. NH2-sites of lysine molecules than cow bone gelatin and fish skin gelatin. These two gelatins are selected for further development of a template for skin tissue regeneration. (C) 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.procbio.2009.11.002

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N-Succinyl chitosan (N-SC) products with various degrees of substitution were synthesized by a direct reaction between chitosan and succinic anhydride. The susceptibility of the as-synthesized polymers to degradation upon their exposure to gamma-ray radiation was investigated. The results were compared with the as-received chitosan. The size exclusion chromatographic results showed that chitosan and N-SC products in their dilute aqueous solution state were more subservient to degradation by gamma-ray radiation than in their solid film state, despite the much less exposure to the radiation (i.e., 5-30 kGy for the solutions versus 20-100 kGy for the films). Increasing the radiation dose resulted in the rather monotonous decrease in the molecular weights of the polymers. Structural analyses of the irradiated polymers by Fourier-transformed infrared spectroscopy (FT-IR) and UV-visible spectrophotornetry indicated the increase in the amount of carbonyl groups with the radiation dose. The formation of the carbonyl groups suggested that the radiolysis of chitosan and N-SC products occurred at the glycosidic linkages. In addition, FT-IR, elemental analysis and proton nuclear magnetic resonance spectroscopy (H-1 NMR) results suggested that gamma-ray radiation affected both the N-acetyl and N-substituted groups on the polymer chains. (C) 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymdegradstab.2009.10.007

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A novel nanocomposite scaffold of chitosan (CS) and bioactive glass ceramic nanoparticles (nBGC) was prepared by blending nBGC with chitosan solution followed by lyophilization technique. The particle size of the prepared nBGC was found to be 100 nm. The prepared composite scaffolds were characterized using techniques Such as Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray diffraction (XRD). The SEM studies showed that the bioactive nBGC were homogenously distributed within the chitosan matrix. The swelling, density, degradation and in-vitro biomineralization studies of the composite scaffolds were also studied. The composite scaffolds showed adequate swelling and degradation properties. The in-vitro biomineralization studies confirmed the bioactivity nature of the composite scaffolds. Cytocompatability of the composite scaffolds were assessed by MTT assay, direct contact test and cell attachment studies. Results indicated no toxicity, and cells attached and spread on the pore walls offered by the scaffolds. These results indicate that composite scaffolds developed using nBGC disseminated chitosan matrix as potential scaffolds for tissue engineering applications. (C) 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.carbpol.2009.08.001

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Biopolymers like chitin are widely investigated as scaffolds in bone tissue engineering. Its properties like biocompatibility, biodegradability, non-toxicity, wound healing ability, antibacterial activity, hemostatic property, etc., are widely known. However, these materials are not much bioactive. Addition of material like silica can improve the bioactivity and biocompatibility of chitin. In this work, chitin composite scaffolds containing nanosilica were prepared using chitin hydrogel and their bioactivity, swelling ability and cytotoxicity was analyzed in vitro. These scaffolds were found to be bioactive in simulated body fluid (SBF) and biocompatible when tested with MG 63 cell line. These results suggest that chitin/nanosilica composite scaffolds can be useful for bone tissue engineering applications. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ijbiomac.2009.06.009

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

Chitin is a novel biopolymer and has excellent biological properties such as biodegradation in the human body and biocompatible, bioabsorable, antibacterial and wound healing activities. In this work, alpha- and beta-chitin membranes were prepared using alpha- and beta-chitin hydrogel. The bioactivity studies were carried out using these chitin membranes with the simulated body fluid solution (SBF) for 7, 14 and 21 days. After 7, 14 and 21 days the membranes were characterized using SEM, EDS and FT-IR. The SEM, EDS and FT-IR studies confirmed the formation of calcium phosphate layer on the surface of the both chitin membranes. These results indicate that the prepared chitin membranes were bioactive. Cell adhesion studies were also carried out using MG-63 osteoblast-like cells. The cells were adhered and spread over the membrane after 24 h of incubation. These results indicated that the chitin membranes could be used for tissue-engineering applications. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ijbiomac.2009.06.002

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

Carboxymethyl chitosan-graft-D-glucuronic acid (CMCS-g-D-GA) was prepared by grafting D-GA onto CMCS in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide(EDC) and then the membranes were made from it. In this work, the bioactivity studies Of CMCS-g-D-GA membranes were carried out and then characterized by SEM, CLSM, XRD and FT-IR. The CMCS-g-D-GA membranes were found to be bioactive. The adsorption of Ni2+, Zn2+ and Cu2+ ions onto CMCS-g-D-GA membranes has also been investigated. The maximum adsorption capacity of CMCS-g-D-GA for Ni2+, Zn2+ and Cu2+ was found to be 57, 56.4 and 70.2 mg/g, respectively. Hence, these membranes were useful for tissue engineering, environmental and water purification applications. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ijbiomac.2009.04.016

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

To investigate the influence of stereogenic centers of sugar-based surfactants for enantiomeric separation, four n-dodecyl thioglycoside sulfates (CMC 1.5-3.6 mM) were chosen as micelle-forming surfactants and five dansylated hydrophobic amino acids were used as test analytes. The analytes were mutually separated by these micelles exhibiting almost similar migration times independent of the used surfactant. Baseline separations of all enantiomers were achieved using both P-D-glucose and P-D-galactose derivates that have an equatorially oriented hydroxy group at C-2 position. In contrast, the ability of enantioseparation was markedly decreased in the case Of P-D-mannose and 2-deoxy-beta-D-glucose derivatives. These results suggested that the structure of C-2 position of the sugar unit, namely presence of an equatorially oriented hydroxy group, is highly important for the enantiomeric separation of the chosen hydrophobic dansylated amino acids.

DOI： 10.1002/elps.200800685

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A novel fibrous membrane of carboxymethyl chitin (CMC)/poly(vinyl alcohol) (PVA) blend was successfully prepared by electrospinning technique. The concentration of CMC (7%) with PVA (8%) was optimized, blended in different ratios (0-100%) and electrospun to get nanofibers. Fibers were made water insoluble by chemical followed by thermal cross-linking. In vitro mineralization studies identified the ability of formation of hydroxyapatite deposits on the nanofibrous surfaces. Cytotoxicity of the nanofibrous scaffold was evaluated using human mesenchymal stem cells (hMSCs) by the MTT assays. The cell viability was not altered when these nanofibrous scaffolds were pre-washed with phosphate buffer containing saline (PBS) before seeding the cells. The SEM images also revealed that cells were able to attach and spread in the nanofibrous scaffolds. Thus Our results indicate that the nanofibrous CMC/PVA scaffold supports cell adhesion/attachment and proliferation and hence this scaffold will be a promising candidate for tissue engineering applications. (C) 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.carbpol.2009.03.009

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Chitosan, a deacetylated derivative of chitin is a commonly studied biomaterial for tissue-engineering applications due to its biocompatibility, biodegradability, low toxicity, antibacterial activity, wound healing ability and haemostatic properties. However, chitosan has poor mechanical strength due to which its applications in orthopedics are limited. Hydroxyapatite (HAp) is a natural inorganic component of bone and teeth and has mechanical strength and osteoconductive property. In this work, HAp was deposited on the surface of chitosan hydrogel membranes by a wet chemical synthesis method by alternatively soaking the membranes in CaCl(2) (pH 7.4) and Na(2)HPO(4) solutions for different time intervals. These chitosan hydrogel-HAp membranes were characterized using SEM, AFM, EDS, FT-IR and XRD analyses. MTT assay was done to evaluate the biocompatibility of these membranes using MG-63 osteosarcoma cells. The biocompatibility studies suggest that chitosan hydrogel-HAp composite membranes can be useful for tissue-engineering applications. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ijbiomac.2009.03.011

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

Chitosan with a molecular weight (MW) of 10(4) Da and 13% degree of acetylation (DA) was extracted from the mycelia of the fungus Gongronella butleri USDB 0201 grown in solid substrate fermentation and used to prepare scaffolds by the freeze-drying method. The mechanical and biological properties of the fungal chitosan scaffolds were evaluated and compared with those of scaffolds prepared using chitosans obtained from shrimp and crab shells and squid bone plates (MW 10(5)-10(6) Da and DA 10-20%). Under scanning electron microscopy, it was observed that all scaffolds had average pore sizes of approximately 60-90 mu m in diameter. Elongated pores were observed in shrimp chitosan scaffolds and polygonal pores were found in crab, squid and fungal chitosan scaffolds. The physico-chemical properties of the chitosans had an effect on the formation of pores in the scaffolds, that consequently influenced the mechanical and biological properties of the scaffolds. Fungal chitosan scaffolds showed excellent mechanical, water absorption and lysozyme degradation properties, whereas shrimp chitosan scaffolds (MW 10(6)Da and DA 12%) exhibited the lowest water absorption properties and lysozyme degradation rate. In the evaluation of biocompatibility of chitosan scaffolds, the ability of fibroblast NIH/3T3 cells to attach on all chitosan scaffolds was similar, but the proliferation of cells with polygonal morphology was faster on crab, squid and fungal chitosan scaffolds than on shrimp chitosan scaffolds. Therefore fungal chitosan scaffold, which has excellent mechanical and biological properties, is the most suitable scaffold to use as a template for tissue regeneration.

DOI： 10.3390/ma2020374

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

The chitin/gelatin composite membranes were prepared by mixing of chitin hydrogel with gelatin. The prepared composite membranes were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), mechanical, swelling, enzymatic degradation and thermal studies. The XRD pattern of the chitin/gelatin composite membranes showed almost the same pattern as (x-chitin. The bioactivity studies of these chitin/gelatin membranes were carried out with the simulated body fluid solution (SBF) for 7, 14 and 21 days followed by the characterization with the scanning electron microscopy (SEM) and Energy Dispersive Spectrum (EDS) studies. The SEM and EDS studies confirmed the formation of calcium phosphate layer on the surface of chitin/gelatin membranes. Biocompatibility of the chitin/gelatin membrane was assessed using human MG-63 osteoblast-like cells. After 48 h of incubation, it was found that the cells had attached and completely covered the membrane surface. Thus, the prepared chitin/gelatin membranes are bioactive and are suitable for cell adhesion suggesting that these membranes can be used for tissue-engineering applications. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ijbiomac.2009.01.006

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

The present study investigates a suitable material, which is expected to have biocompatibility and to promote tissue regeneration. For this purpose, we have chosen chitin that was chemically modified by phosphorylation with high degree of substitution. The phosphorylated chitin (P-chitin) was synthesized using the H3PO4/P2O5/ET3PO4/hexanol method. The structure of P-chitin was analyzed by FTIR, P-31- and C-13-NMR spectroscopic studies, scanning electron microscopy, and X-ray diffraction. The thermal properties of the P-chitin were also characterized by thermogravimetric analyses. The highly phosphorylated chitin derivatives prepared by this method were soluble in water and amorphous in nature. Thus, H3PO4/P2O5/ET3PO4/hexanol method provides a versatile and alternative route for synthesis of P-chitin, which would be useful for biomedical applications. POLYM. ENG. SCI., 49:844-849, 2009. (C) 2009 Society of Plastics Engineers

DOI： 10.1002/pen.21306

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Chitin and chitosan are novel biomaterials. The novel chitosan/gelatin membranes were prepared using the suspension of chitosan hydrogel mixed with gelatin. The prepared chitosan/gelatin membranes were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), mechanical, swelling, and thermal Studies. The morphology of these chitosan/gelatin membranes was found to be very smooth and homogeneous. The XRD studies showed that the chitosan/gelatin membranes have good compatibility and interaction between the chitosan and gelatin. The stress and elongation of chitosan/gelatin membranes on wet condition showed excellent when the mixture ratio of gelatin was 0.50. The prepared chitosan/gelatin membranes showed good swelling, mechanical and thermal properties. Cell adhesion studies were also carried out using human MG-63 osteoblast-like cells. The cells incubated with chitosan/gelatin membranes for 24 h were capable of forming cell adhesion. Thus the prepared chitosan/gelatin membranes are bioactive and are suitable for cell adhesion suggesting that these membranes can be used for tissue-engineering applications. Therefore, these novel chitosan/gelatin membranes are useful for biomedical applications. (C) 2008 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.carbpol.2008.10.015

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Fully acetylated dodecyl thioglycosides were found to be useful as glycosyl donors by activation with 1-benzenesulfinyl piperidine (BSP) and triflic anhydride (Tf2O) at -78 degrees C. The glycosyl acceptor was added to the reaction mixture at the same temperature to furnish various disaccharide, including the protected Lewis a (Le(a)) trisaccharide, in good yields. (C) 2008 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.carres.2008.11.008

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

The major problem associated with the production of alginate/chitosan hybridized fibers by wet spinning is the formation of gels due to ionic interactions of the oppositely charged molecules of alginate and chitosan when these two polymers are directly mixed. Here, we proposed a novel method of using chitosan in the form of an emulsion. The emulsion was prepared by adding a primary emulsion of olive oil in a sodium dodecyl sulfate (SDS) aqueous solution into a chitosan-citrate complex. The complexation of chitosan with citric acid is the key of this method. The citrate ions neutralize the positive charges of chitosan, rendering the chitosan-citrate complex to readily penetrate into the core of the SDS/olive oil micelles. The obtained emulsified chitosan-citrate complex (hereafter, the chitosan-citrate emulsion) of varying amount was then added into an alginate aqueous solution to prepare the alginate/chitosan spinning dope suspensions. The alginate/chitosan hybridized fibers showed spotty features of the emulsified chitosan-citrate complex particles locating close to the surface and the inside of the hybridized fibers. At the lowest content of incorporated chitosan (i.e., 0.5% w/w chitosan), both the tenacity and the elongation at break of the obtained chitosan-spotted alginate fibers were the greatest. Further increase in the chitosan content resulted in a monotonous decrease in the property values. Lastly, preliminary studies demonstrated that the obtained chitosan-spotted alginate fibers showed great promises as carriers for drug delivery.

DOI： 10.1021/bm801043d

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

Alginate/phosphorylated chitin (P-chitin) blend films were prepared by mixing of 2% of alginate and P-chitin in water and then cross-linked with 4% CaCl(2) solution. The blended films were characterized by FT-IR. Then, the bioactivity of blend films was studied by biomimetic method in simulated body fluid solution (SBF) for 7,14 and 21 days. After 7, 14 and 21 days and films were characterized by FT-IR and SEM studies. The SEM and FT-IR studies showed that the hydroxyapatite was formed on the surface of the blend films after 7,14 and 21 days in the SBF solution. These studies confirmed that the alginate/P-chitin blend films are bioactive. Furthermore, the adsorption of Ni(2+), Zn(2+) and Cu(2+) onto alginate/P-chitin blend films has been investigated. The parameters studied include the pH, contact time, and initial metal ion concentrations. The maximum adsorption capacity of alginate/P-chitin blend films for Ni(2+), Zn(2+) and Cu(2+) at pH 5.0 was found to be 5.67, 2.85 and 11.7 mg/g, respectively. These results suggest that alginate/P-chitin blend films-based technologies may be developed for water purification and metal ions separation and enrichment. (C) 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ijbiomac.2008.10.010

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Chitosan with a molecular weight (MW) of 104 Da and 13% degree of acetylation (DA) was extracted from the mycelia of the fungus Gongronella butleri USDB 0201 grown in solid substrate fermentation and used to prepare scaffolds by the freezedrying method. The mechanical and biological properties of the fungal chitosan scaffolds were evaluated and compared with those of scaffolds prepared using chitosans obtained from shrimp and crab shells and squid bone plates (MW 105-106 Da and DA 10-20%). Under scanning electron microscopy, it was observed that all scaffolds had average pore sizes of approximately 60-90 μm in diameter. Elongated pores were observed in shrimp chitosan scaffolds and polygonal pores were found in crab, squid and fungal chitosan scaffolds. The physico-chemical properties of the chitosans had an effect on the formation of pores in the scaffolds, that consequently influenced the mechanical and biological properties of the scaffolds. Fungal chitosan scaffolds showed excellent mechanical, water absorption and lysozyme degradation properties, whereas shrimp chitosan scaffolds (MW 106Da and DA 12%) exhibited the lowest water absorption properties and lysozyme degradation rate. In the evaluation of biocompatibility of chitosan scaffolds, the ability of fibroblast NIH/3T3 cells to attach on all chitosan scaffolds was similar, but the proliferation of cells with polygonal morphology was faster on crab, squid and fungal chitosan scaffolds than on shrimp chitosan scaffolds. Therefore fungal chitosan scaffold, which has excellent mechanical and biological properties, is the most suitable scaffold to use as a template for tissue regeneration. © 2009 by the authors.

DOI： 10.3390/ma2020374

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The first total synthesis of a unique tetrasaccharide repeating unit of lipopolysaccharide from Salmonella enteritidis has been accomplished by assembly of dodecyl thioglycosides. The crucial key steps were preparation of a rare branched dideoxy sugar, D-tyvelose (3,6-dideoxy-D-arabino-D-hexose) and sequential regioselective glycosylation at 23-positions of a central D-mannose residue 5 with D-tyvelose 6 and D-galactose donors 7. (C) 2008 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2008.06.097

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Chitin is a natural biopolymer have been used for several biomedical applications due to its biodegradability and biocompatibility. By using the calcium solvent system, chitin regenerated hydrogel (RG) was prepared by using alpha-chitin. And also, the swelling hydrogel (SG) was prepared by using beta-chitin with water. Then, both RG and SG were mixed with gelatin and N-acetyl-D-(+)-glucosamine (GlcNAc) at 120 degrees C for 2 h. The chitin/gelatin membranes with GlcNAc were also prepared by using RG and SG with GlcNAc. The prepared chitin/ gelatin membranes with or without GlcNAc were characterized by mechanical, swelling, enzymatic degradation, thermal and growth of NIH/3T3 fibroblast cell studies. The stress and elongation of chitin/gelatin membrane with GlcNAc prepared from RG was showed higher than the chitin/gelatin membranes without GlcNAc. But, the chitin/gelatin membranes prepared from SG with GlcNAc was showed higher stress and elongation than the chitin/gelatin membranes without GlcNAc. It is due to the crosslinking effect of GlcNAc. The chitin/gelatin membranes prepared from SG showed higher swelling than the chitin/gelatin membranes prepared from RG. In contrast, the chitin/gelatin membranes prepared from RG showed higher degradation than the chitin/gelatin membranes prepared from SG. And also, these chitin/gelatin membranes are showing good growth of NIH/3T3 fibroblast cell. So these novel chitin/gelatin membranes are useful for tissue engineering applications. (C) 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.carbpol.2007.12.011

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Chitin is a natural biopolymer that has been investigated for its prospected biomedical applications due to its several biological advantages. However, the chitin is very difficult to dissolve in common solvents due to its rigid crystalline structure. But it is soluble in saturated calcium solvent system under mild conditions. By using the calcium solvent system, chitin regenerated hydrogel (RG) was prepared by using a-chitin. And we also prepared swelling hydrogel (SG) by using beta-chitin with water. In addition, the SG was mixed with glutaraldehyde (GA) or N-acetyl D-(+)-glucosamine (GlcNAc) at 120 degrees C for 2 h. The chitin membranes were prepared by using RG and SG with or without GA or GlcNAc. The prepared chitin membranes were characterized by mechanical, swelling, enzymatic degradation, thermal, and growth of NIH/3T3 fibroblast cell studies. The stress and elongation of chitin membranes prepared from SG with GA or 10%, (w/w) GlcNAc were increased due to the cross-linking effect. The chitin membranes prepared from SG showed higher swelling and degradation than the membranes prepared from RG. Moreover, the chitin membranes prepared from SG with GA or GlcNAc showed lower swelling and degradation than the untreated one. The thermal studies showed that the chitin membranes prepared from RG showed higher thermal stability than the other chitin membranes prepared from SG. And also, these membranes showed good growth of NIH/3T3 fibroblast cells although a little aggregation of cells was observed. So, these chitin membranes are promising biomaterials that can be useful for tissue engineering applications. (C) 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.carbpol.2007.11.034

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

Four novel chiral anionic surfactants having carbohydrate hydrophilic heads, sodium n-dodecyl 1-thio-beta-D-glucopyranoside 6-hydrogen sulfate (6-beta GlcD), sodium n-dodecyl 1-thio-beta-L-glucopyranoside 6-hydrogen sulfate (6-beta GlcL), sodium n-dodecyl 1-thio-beta-L-fucopyranoside 3-hydrogen sulfate (3-beta FucL), and sodium n-dodecyl 1-thio-alpha-L-rhamnopyranoside 3-hydrogen sulfate (3-alpha RhaL), were synthesized by selective sulfation of the corresponding thioglycosides. Their CMC determined by fluorescence using pyrene as a probe in water was 1.3-2.7 mM. These surfactants found to be useful as chiral selectors for enantiomeric separation by MEKC. The enantiomeric separation was optimized with respect to pH, buffer concentration, and surfactant concentration. Under the optimized conditions (50 mM phosphate buffer at pH 6.5, 30 mM surfactant, 20 W), the enantiomeric separations of five dansylated amino acids (Dns-AAs) were achieved within approximately 20 min with the migration order of Val < Met < Leu < Phe < Trp. With 6-PGlcD, all D-forms of Dns-AAs were found to migrate faster than the corresponding L-forms, whereas the migration order of the enantiomers was completely reversed with the surfactant 6-beta GlcL having iriversed absolute configuration of 6-beta GlcD. Among four surfactants examined, beta-anomers were much superior chiral selectors than alpha-anomers, and the maximum resolution was obtained. with the 6-deoxy sugar, 3-beta FucL. These results indicated that the structures of the surfactant head groups including their anomeric configurations have significant effects on the enantiomeric separation and the migration behavior in MEKC.

DOI： 10.1002/elps.200800045

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

Chitin is a biopolymer and it is non-toxic, biodegradable and biocompatible. Chitin has many potential industrial applications because of its abundance, biodegradability, non-toxicity, chemical inertness. beta-chitin scaffolds were prepared by using saturated calcium chloride alcoholic solution (CaCl2.6H(2)O/EtOH) and then followed by dialysis with lyophilization. The prepared P-chitin scaffolds were characterized by FT-IR, scanning electron microscopy (SEM) and thermogravimetric (TGA). The preliminary bioactivity studies of beta-chitin scaffolds were studied by using simulated body fluid (SBF) solution for 7,14 and 21 days. We also immersed the beta-chitin scaffolds in saturated aqueous CaCl2 and Na2HPO4 solution over 12 h. After 7,14 and 21 days, the scaffolds were characterized by SEM and FT-IR studies. The SEM studies showed that there is a calcium phosphate layer in the surface as well as in the cross-section of beta-chitin scaffolds. It seems that the beta-chitin scaffolds are useful in the tissue-engineering field. (c) 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ijbiomac.2008.03.002

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

The crystalline structure of beta-chitin from squid pen was investigated by X-ray diffraction (XRD). The purified beta-chitin was prepared from bigfin reefsquid pen. P-Chitin was treated with saturated calcium chloride dihydrate/alchohol (CaCl(2 center dot)2H(2)O/MeOH) solvent system at different conditions for XRD studies. The change of crystallinity of beta-chitin from squid pen was studied by using the fiber photographs on imaging plates. The results showed that the diffraction peak (0 10) was shifted. It means that the lattice plane (010) interplanarilly spreaded to 3.4 angstrom, when the squid pen was washed with water after treatment of Ca solvent. Furthermore, when the squid pen was dried after treatment of Ca solvent and washing with water, interplanar spacing of (0 10) inversely shrank to 1.1 angstrom. These results suggested that Ca solvent especially influences the plane (010) of beta-chitin structure. (c) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ijbiomac.2007.10.011

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

Chitosan a natural based polymer is non-toxic, biocompatible and biodegradable. Chemical modification of chitosan to generate new bifunctional materials and finally would bring new properties depending on the nature of the group introduced. In our present study, we prepared phosphorylated chitosan (P-chitosan) by using H3PO4/P2O5/Et3PO4/hexanol method. From our present method, we got high yield and high degree of substitution (DS). The prepared P-chitosan (DS-1.18) was characterized by FT IR, C-13 NMR, P-31 NMR, elemental, XRD, TGA, DTA and SEM studies. After the phosphorylation, the solubility of the polymer was improved. The P-chitosan showed less thermal stability and crystallinity than the chitosan. It was due to the phosphorylation. (c) 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ijbiomac.2007.12.011

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

Dodecyl thioglycosides (3, 4, 5) were prepared by conventional transformation of D-glucose and used as new glycosyl donors for a short-step synthesis of phytoalexin elicitor heptaglucoside. A gentio-tetraoside derivative (6) having three hydroxyl groups was synthesized by NIS-TfOH promoted glycosylate in more than 90% yield followed by selective removal of temporary protective groups. Undesired formation of alpha-glycosides at the introduction of beta-(1 -> 3)-branches into gentio-oligosaccharides was found to be suppressed by use of a thiophilic reagent system, BSP (1-benzenesulfinyl piperidine)-Tf(2)O, giving the heptaglucoside in only four glycosylation steps.

DOI： 10.1039/b800809d

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：WILEY-V C H VERLAG GMBH  

Chitin, a natural abundant polysaccharide, have been investigated as prospected biochemical material due to its several biological advantages. It is insoluble in the most of the organic solvents due to its rigid crystalline structure. However, chitin regenerated hydrogel (RG) has been prepared by using the saturated calcium solvent system under mild conditions. And also, swelling hydrogel (SG) was prepared by using water. In this study, we prepared the suspension of chitinous hydrogel, and applied to fabricated the chitinous compound/gelatin composite sheets. Additionally, N-acetyl D-(+)-glucosamine was added into some composite sheets. We investigated the mechanical properties and growth of NIH/3T3 fibroblast cell for the prepared composite sheet.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：WILEY-V C H VERLAG GMBH  

Chitin is a polysaccharide found in the outer skeleton of insects, crabs, shrimps, and lobsters and in the internal structures of other invertebrates. Sulfated chitin was prepared by reacting carboxymethyl chitin (CM-chitin) with 2-aminoethane sulfonic acid by using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) catalyst. The prepared sulfated chitin was characterized by FTIR, elemental analysis, thermo-gravimetric analysis (TGA) and X-ray diffraction (XRD). The degree of substitution was found to be 0.98 by elemental analysis. The TGA studies showed that sulfated chitin was less thermal stability than carboxymethyl chitin. This is due to the grafting reaction. The sulfated chitin membranes were prepared from sulfated chitin and then crosslink with glutaradehyde. The biodegradation process was performed in PBS (pH 7.4) containing lysozyme (10 mu g/ml) at 37 degrees C in an incubator. Experimental results from weight loss throughout the study showed that the biospecific degradation occur on the membrane by lysozyme.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Calcium alginate beads covalently linked with alpha-cyclodextrin (alpha-CD-alginate beads) were prepared and examined for their ability to serve as a supporting matrix for bacterial degradation of nonylphenol, an endocrine disruptor. Column chromatographic experiment using alpha-CD-alginate beads with diameter of 657 +/- 82 mu m and with degree of CD substitution of 0.16 showed a strong affinity for nonylphenol adsorption. Although addition of alpha-CD (2.7-27 mM) to the culture broth of Sphingomonas cloacae retarded nonylphenol degradation, the immobilized bacteria on the CD-alginate beads were effective for the degradation. Batch degradation tests using the immobilized bacteria on alpha-CD-alginate-beads showed 46% nonylphenol recovery after 10-day incubation at 25 +/- 2 degrees C, and the recovery reached to about 17% when wide and shallow incubation tubes were used to facilitate uptake of the viscous liquid of nonylphenol on the surface of the medium. Scanning electron microscopic photographs revealed that multiplicated bacteria was present both on the surface and inside the beads and the matrix of CD-alginate was stable and suitable during 10-day incubation. (c) 2006 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.biortech.2006.08.009

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

A simple and efficient method to remove hydrophobic phenolic pollutants from aqueous solutions has been investigated using the inclusion ability and cationic property of mono(6amino-6-deoxy)-alpha-cyclodextrin (ACD) and a cation exchanger. The inclusion complexes of nonylphenol and bisphenol A with ACD were almost completely adsorbed onto a column of a cation exchanger and desorbed with diluted aqueous ammonia solution. Moreover, bisphenol A was also adsorbed on a column of the cation exchanger that was pretreated with ACD.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

The inclusion ability on alginate, a hydrogel forming polysaccharide, has been introduced by covalently linking alpha-cyclodextrin (alpha-CD). The secondary hydroxyl groups of sodium alginate were activated with cyanogen bromide and subsequently reacted with 6-amino-alpha-CD. The degree of substitution (DS) of the resulting alpha-CD linked alginate was 0.05-1.58 depending on reaction condition and the ratio of 6-amino-alpha-CD and alginate. Using p-nitrophenol as a model compound in UV-vis and circular dichroism spectroscopic examination, the modified polysaccharide showed an ability to form a host-guest complex. Furthermore, the alpha-CD linked alginate found to be provided the spherical beads by treating with a calcium chloride solution. (c) 2005 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2005.08.005

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

An affinity labeling reagent, uridine 5'-(6-amino-{2-[(7-bromomethyl-2-naphthyl)methoxy-carbonylmethoxy]ethoxy}acetyl-6-deoxy-alpha-D-galactopyranosyl) diphosphate (1a), was designed on the basis of 3D docking simulation and synthesized to investigate the functional role of Trp310 residue located in the small loop near the active site of human recombinant galactosyltransferase (beta GalT-1). Mass spectrometric analysis revealed that the Trp310 residue of beta GalT1 can be selectively modified with the naphthylmethyl group of compound la at the C-3 position of the indole ring. This result motivated us to synthesize novel uridine-5'-diphosphogalactose (UDP-Gal) analogues as candidates for mechanism-based inhibitors for beta GalT-1. We found that uridine 5'-(6-O-[10-(2-naphthyl)-3,6,9-trioxadecanyl]-alpha-D-galactopyranosyl) diphosphate (2) is the strongest inhibitor (K-i = 1.86 mu M) against UDP-Gal (K-m = 4.91 mu M) among compounds reported previously. A cold spray ionization time-of-flight mass spectrometry study demonstrated that the complex of this inhibitor and beta GalT-1 cannot interact with an acceptor substrate in the presence of Mn2+.

DOI： 10.1021/jm0504297

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Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.tet.2004.12.035

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

A facile and versatile method to remove hydrophobic and phenolic pollutants in aqueous media has been investigated using the ionic interaction of mono (6-amino-6-deoxy)- a -cyclodextrin (aminoCD) and cation exchanger. Each inclusion complex of the aminoCD with nonylphenol or bisphenol A in water was found to be adsorbed quantitatively onto a column of the cation exchanger (CM-Sephadex C-25, NH4- form) and eluted completely with diluted aqueous ammonia solution.

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

Mono-, di-, and trisialyloligosaccharides were introduced to mutant insulins through enzymatic reactions. Sugar chains were sialylated by alpha2,6-sialyltransferase (alpha2,6-SiaT) via an accessible glutamine residue at the N-terminus of the B-chain attached by transglutaminase (TGase). Sia2,6-di-LacNAc-Ins(B-F1Q) and Sia2,6-tri-LacNAc-Ins(B-F1Q), displaying two and three sialyl-N-acetyllactosamines, respectively, were administered to hyperglycemic mice. Both branched glycoinsulins showed prolonged glucose-lowering effects compared to native or lactose-carrying insulins, showing that sialic acid is important in obtaining a prolonged effect. Sia2,6-tri-LacNAc-lns(B-F1Q), in particular, induced a significant delay in the recovery of glucose levels.

DOI： 10.1021/ja0464261

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

A novel chitosan-based polymeric surfactant, DG-chitosan, was prepared via reductive N-alkylation of chitosan with 3-O-dodecyl-D-glucose in acetate buffer (pH 4.3, 0.1 M)-methanol in the presence of sodium cyanoborohydride (NaBH3CN). DG-chitosan was swelling in water, partly dissolvable in pyridine and DMF, and completely soluble in 0.1% aqueous acetic acid. H-1 and C-13 NMR spectroscopic analyses in 2% acetic acid-d(4)-methanol-d(4) together with elemental analysis showed the degree of substitution was 27%. Formation of polymeric micelles was observed by use of pyrene as a fluorescent probe, and the critical aggregation concentration (CAC) of DG-chitosan was marked equal to 28.1 mg/L. (C) 2003 Published by Elsevier Ltd.

DOI： 10.1016/j.polymer.2003.11.034

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

Multivalent glycoclusters have the potential to become pharmaceuticals by virtue of their target specificity toward clinically relevant sugar receptors. Their application can also provide fundamental insights into the impact of two spatial factors on binding, i.e., topologies of ligand (branching mode, cluster presentation) and carbohydrate recognition domains in lectins. Persubstituted macrocycles derived from nucleophilic substitution of iodide from heptakis 6-deoxy-6-iodo-beta-cyclodextrin by the unprotected sodium thiolate of 3-(3-thioacetyl propionamido)propyl glycosides (galactose, lactose and N-acetyllactosamine) were prepared. The produced glycoclusters were first tested as competitive inhibitors in solid-phase assays. A plant toxin from mistletoe and an immunoglobulin G fraction from human serum were markedly susceptible. A nearly 400-fold increase in inhibitory potency of each galactose moiety in the heptavalent form relative to free lactose (217-fold relative to free galactose) was detected. Thus, these glycoclusters can efficiently interfere, for example, with xenoantigen-dependent hyperacute rejection. Among the tested galectins selected from this family of adhesion- and growth-regulatory endogenous lectins, the substituted beta-cyclodextrins acted as sensors to delineate topological differences between the two dimeric prototype proteins. The relatively strong reactivity with chimera-type galectin-3, a mediator of tumor metastasis, disclosed selectivity for glycocluster binding among galectins. Equally important, the geometry of ligand display (maxiclusters, bi- or triantennary N-glycans) made its mark on the inhibitory potency. To further determine the sensitivity of a distinct galectin presented on the cell surface and not in solution, we established a stably transfected tumor cell clone. We detected a significant response to presence of the multivalent inhibitor. This type of chemical scaffold with favorable pharmacologic properties might thus be exploited for the design of galectin- and ligand-type-selective glycoclusters.

DOI： 10.1021/bc0340666

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

An efficient and versatile method for the synthesis of a biantennary octasaccharide derivative was established by combined chemical and enzymatic manipulations of 1,6-anhydro-beta-lactose as a key starting material. A key 1,6-anhydro-beta-lactose derivative having two unprotected hydroxyl groups at C-3' and C-6' positions was prepared and employed for the chemical coupling reaction with a known 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl imidate to afford a tetrasaccharide derivative with two GlcNAc branches in 69% yield. Enzymatic galactosylation using UDP-Gal with a bovine milk beta1,4-galactosyltransferase and subsequent sialylation with a recombinant alpha,2,3-sialyltransferase in the presence of CMP-Neu5Ac proceeded smoothly and gave a desired model compound, a bivalent sialooctasaccharide (1), in 73% overall yield from the tetrasaccharide intermediate. (C) 2003 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0040-4020(03)00711-7

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

A novel class of sulfated glycolipids with excellent self-assembling capacity to form stable monolayers at an air-water interface and specific erythrocyte-like liposomes was synthesised from alpha, beta, and gamma-cyclodextrins as starting materials.

DOI： 10.1039/b110673b

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

A simple and highly practical method for the synthesis of cyclodextrin-scaffolded glycoclusters recognized specifically by lectins is described. Nucleophilic displacement of iodide from heptakis 6-deoxy-6-iodo-beta -cyclodextrin by unprotected sodium thiolates derived from 3-(3-thioacetyl propionamido)propyl glycosides proceeded smoothly in mild condition and gave novel per-glycosylated cyclodextrins (glycocyclodextrins, glycoCDs) having D-galactose, N-acetyl-D-glucosamine, lactose or N-acetyllactosamine residues in high yields (78-88%). It was demonstrated that all these per-glycosylated P-cyclodextrins showed amplified inhibitory effects on the erythrocytes agglutination induced by wheat germ (Triticum vulgaris) agglutinin (WGA) or Erythrina corallodendron lectin (ECorL). (C) 2000 Elsevier Science Ltd. All rights reserved.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

Glycosyltransferases are important synthetic enzymes for the construction of naturally occurring glycoconjugates as well as for the design of neoglycoconjugates. The assay methods currently available for these enzymes require tedious and time consuming procedures for separation of products and do not permit continual assay of enzyme activities. As a set of convenient fluorogenic substrates for continuous monitoring of sialyltransferase activities, we designed and synthesized a novel CMP-Neu5Ac derivative with a naphthylmethyl group at the C-9 position and N-acetyllactosamine derivative containing a dansyl group at the terminal position of aglycon. In such substrates, the emission peak of the naphthylmethyl group (lambda(em) = 340 nm) of the glycosyl donor is successfully overlapped with the excitation peak due to the dansyl group (lambda(ex) = 335 nm) of the glycosyl acceptor. A coupling reaction of these two substrates catalyzed by rat liver 2,6-sialyltransferase caused an increase of dansyl fluorescence (lambda(em) = 525 nm) and a decrease of naphthylmethyl fluorescence on the basis of resonance energy transfer between two fluorescence probes. The substrates presented here permit continuous fluorescent monitoring of enzymatic sugar combining reactions. Actually, using this time course of enzymatic reactions, kinetic constants of rat liver 2,6-sialyltransferase against glycosyl donor substrates were estimated to be K-m = 4.85 mu M and V-max = 0.119 mu mol/min, respectively. This strategy allows precise and efficient analyses of enzyme kinetics not possible with the conventional assay methods for the glycosyltransferases that usually require separation of products from the reaction mixture. (C) 2000 Academic Press.

DOI： 10.1006/abio.2000.4632

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

An efficient method for the synthesis of novel glycopolymers with triantennary sialooligosaccharides showing potent anti-influenza virus activity is described. Polymerisable glycoside of triantennary N-acetyllactosamine [beta-D-galactopyranosyl-(1-->4)-2-acetamido-2-deoxy-D-glucopyranose, Gal beta(1-->4)GlcNAc] is synthesised from lactose and 4-(3-hydroxypropyl)-4-nitroheptane-1,7-diol as key starting materials, and converted into water-soluble glycopolymers by radical copolymerisation with acrylamide. Subsequent enzymic sialylation using cytidine 5'-monophospho-N-acetylneuraminic acid (CMP-Neu5Ac) with alpha-2,3-sialyltransferase from porcine liver or with alpha-2,6-sialyltransferase from rat liver gives novel glycoprotein mimics having potent inhibitory activity against influenza virus infection. It is demonstrated that the present triantennary glycoligands exhibit much higher biological activities than the effects by glycopolymers derived from the simple monovalent-type glycomonomers.

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

A simple and facile method for the synthesis of novel 6-persubstituted beta-cyclodextrin derivatives having a sugar cluster through a spacer arm is described. The coupling reaction of per-6-iodo-beta-CD with each derivative of D-galactose (Gal) or N-acetyl-D-glucosamine (GlcNAc) smoothly proceeded and gave the corresponding cyclodextrin derivatives having seven sugar residues in excellent yields.

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Language：English   Publisher：The Chemical Society of Japan  

Versatile intermediates for the syntheses of cell-surface oligosaccharides bearing <i>N</i>-acetyllactosamine units have been prepared from a readily available 1,6-anhydro-<i>β</i>-lactose as a key starting material. Regioselective chemical manipulations of 1,6-anhydro-<i>β</i>-lactose were carried out in a stepwise procedure and gave fully-protected lactosamine derivatives. It was clearly suggested that modification at C-3′ position of the galactose residue and the following introduction of a sterically hindered leaving group at C-2 position of the reducing glucose remarkably accelerated and facilitated further derivatization of this potential disaccharide material. Selective generation of hydroxyl groups at C-3, C-3′, and/or C-6′ positions proceeded smoothly in mild conditions and afforded a series of fully-functionalized disaccharide-acceptors in high yields.

DOI： 10.1246/bcsj.69.411

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

A simple and facile method for the syntheses of cluster-type homopolymers from omega-(acrylamido)alkyl glycosides of N-acetyllactosamine [beta-D-Galp-(1--&gt;4)-beta-n-GlcpNAc] is described. An efficient procedure for the preparation of poly[omega-(acrylamido)alkyl O-(beta-D-galactopyranosyl)-(1--&gt;4)-2-acetamido-2-deoxy-beta-D-glucopyranoside] was established on the basis of radical polymerization of the novel glycosides in the presence of ammonium persulfate and N,N,N&apos;,N&apos;-tetramethylethylenediamine. These synthetic cluster glycopolymers exhibited good solubility in water and had sugar densities much higher than the glycopolymers derived from known n-pentenyl glycosides. The association constants of Erythrina corallodendron lectin (ECorL) with these cluster glycopolymers were evaluated by measuring the changes in fluorescence intensity of fluorescent-labeled ECorL induced by the addition of the polymeric ligands. Addition of the cluster-type glycopolymers having different degrees of N-acetyllactosamine density to ECorL induced a significant decrease of the fluorescence intensity at 520 nm, and this phenomenon was used for the determination of binding constants between the glycopolymers and ECorL.

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

Radical copolymerization of a polymerizable dansyl derivative, N-2-propenyl-(5-dimethylamino)-1-naphthalene sulfonamide, with sugar monomers and acrylamide proceeded smoothly in aqueous solution in the presence of ammonium persulfate and N,N,N',N'-tetramethylethylenediamine and afforded a novel type of water-soluble glycopolymers having fluorescent side-chains, Fluorescence emission spectra of these polymeric sugar-ligands by excitation at 340 nm revealed maxims at 448 and 528 nm, When the glycopolymer carrying galactose residues was saturated with Ricinus communis agglutinin (RCA(60)), the fluorescence emission maxima at 448 and 528 nm were not shifted significantly, although the fluorescence intensities were decreased by 20 and 14%, respectively. Polymeric sugar-cluster effects drastically enhanced the association constants of galactose residues with RCA(60) in the order of 10(8) M(-1). The significance for efficient binding of galactose density on the glycopolymer was also demonstrated by using glycopolymers with different degrees of galactose branching.

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Language：Japanese  

CiNii Books

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Language：Japanese  

CiNii Books

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：AMER CHEMICAL SOC  

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：AMER CHEMICAL SOC  

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：AMER CHEMICAL SOC  

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Language：English   Publisher：WILEY-V C H VERLAG GMBH  

Chitin, a natural abundant polysaccharide, have been investigated as prospected biochemical material due to its several biological advantages. It is insoluble in the most of the organic solvents due to its rigid crystalline structure. However, chitin regenerated hydrogel (RG) has been prepared by using the saturated calcium solvent system under mild conditions. And also, swelling hydrogel (SG) was prepared by using water. In this study, we prepared the suspension of chitinous hydrogel, and applied to fabricated the chitinous compound/gelatin composite sheets. Additionally, N-acetyl D-(+)-glucosamine was added into some composite sheets. We investigated the mechanical properties and growth of NIH/3T3 fibroblast cell for the prepared composite sheet.

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Language：Japanese  

CiNii Books

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：OXFORD UNIV PRESS INC  

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：OXFORD UNIV PRESS INC  

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：OXFORD UNIV PRESS INC  

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Language：English  

CiNii Books

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Venue：Yojyakarta, Indonesia  

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Venue：Yojyakarta, Indonesia  

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Venue：Penang, Malaysia  

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Venue：那覇  

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Venue：那覇  

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Venue：神戸  

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Venue：神戸  

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Venue：Spain  

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Venue：船堀  

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Venue：船堀  

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Venue：幕張  

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Venue：幕張  

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Venue：吹田  

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Venue：吹田  

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Venue：吹田  

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Venue：吹田  

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Venue：吹田  

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Venue：Yangon, Myanmar  

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Venue：Kaohsiung Taiwan  

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Venue：東京  

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Venue：東京  

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Venue：東京  

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Venue：東京  

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Venue：Kaohsiung Taiwan  

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Venue：神戸  

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Venue：鹿児島  

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Venue：神戸  

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Venue：東京  

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Venue：東京  

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Venue：名古屋  

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Venue：名古屋  

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Venue：名古屋  

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Venue：名古屋  

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Venue：Bangkok, Thailand  

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Venue：Bangkok, Thailand  

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Venue：Bangkok, Thailand  

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Venue：吹田  

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Venue：吹田  

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Venue：吹田  

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Venue：吹田  

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Venue：吹田  

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Venue：Yonago, Japan  

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Venue：Yonago, Japan  

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Venue：Yonago, Japan  

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Venue：Yonago, Japan  

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Venue：金沢  

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Venue：金沢  

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Venue：豊田  

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Venue：Suita, Japan  

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Venue：Suita, Japan  

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Venue：神戸  

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Venue：神戸  

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Venue：東京  

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Venue：東京  

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Venue：京都  

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Venue：Bangkok, Thailand  

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Venue：Bangkok, Thailand  

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Venue：Bangkok, Thailand  

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Venue：Bangkok, Thailand  

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Venue：Sapporo, Japan  

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Venue：Sapporo, Japan  

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Venue：Penang, Malaysia  

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Venue：Penang, Malaysia  

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Venue：Bangkok, Thailand  

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Venue：Bangkok, Thailand  

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Venue：Bangkok, Thailand  

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Venue：Osaka, Japan  

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Venue：Osaka, Japan  

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Venue：Osaka, Japan  

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Venue：Nha Trang, Vietnam  

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Venue：日本大学  

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Venue：福井大学  

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Venue：大阪市大  

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Venue：大阪市大  

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Venue：大阪市大  

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Venue：関西大学  

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Venue：関西大学  

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Venue：新潟朱鷺メッセ  

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Venue：新潟朱鷺メッセ  

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Venue：新潟朱鷺メッセ  

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Venue：新潟朱鷺メッセ  

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Venue：新潟朱鷺メッセ  

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Venue：新潟朱鷺メッセ  

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Venue：新潟朱鷺メッセ  

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Venue：新潟朱鷺メッセ  

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Venue：新潟朱鷺メッセ  

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Venue：東京医科歯科大学  

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Venue：船堀  

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Venue：船堀  

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Venue：横浜パシフィコ  

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Venue：横浜パシフィコ  

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Venue：神戸  

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Venue：神戸  

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Venue：神戸  

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Venue：東京船越  

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Venue：横浜パシフィコ  

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Venue：Bangkok, Thailand  

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Venue：Kobe, Japan  

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Announcement no：2012-234083  Date announced：2012.12

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