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Хитины и хитозаны (литература за 2010-2014 гг.)

Журнальные статьи

1.U47967
Chen, Jyh-Ping; Kuo, Chang-Yi; Lee, Wen-Li Thermo-responsive wound dressings by grafting chitosan and poly(N-isopropylacrylamide) to plasma-induced graft polymerization modified non-woven fabrics // APPLIED SURFACE SCIENCE Volume: 262 Pages: 95-101 Published: DEC 1 2012

To obtain a chitosan wound dressings with temperature-responsive characteristics, polypropylene (PP) non-woven fabric (NWF) was modified by direct current pulsed oxygen plasma-induced grafting polymerization of acrylic acid (AAc) to improve hydrophilicity and to introduce carboxylic acid groups. Conjugation of chitosan and poly(N-isopropylacrylamide) (PNIPAAm) followed by using water-soluble carbodiimide as a coupling agent to form a novel bigraft PP-g-chitosan-g-PNIPAAm wound dressing. The amount of chitosan and PNIPAAm grafted to PP-g-chitosan-g-PNIPAAm were 83.0 +/- 4.6 mu g/cm(2) and 189.5 +/- 8.2 mu g/cm(2), respectively. The surface chemical composition and microstructure of the NWF were studied by electron spectroscopy for chemical analysis (ESCA) and scanning electron microscopy (SEM). The linkages between AAc, chitosan, and PNIPAAm were confirmed with the formation of amide bonds. Physical properties of the NWF were characterized and potentials of these NWFs as wound dressings were evaluated using SD rat as the animal model. NWFs contained PNIPAAm were better than those contained only chitosan in wound healing rates and the wound areas covered by PP-g-chitosan-g-PNIPAAm wound dressings healed completely in 17 days. (c) 2012 Elsevier B.V. All rights reserved.

2.U03117
1.Applied Physics Letters (USA). 2010 г., т. 97, N 5, (DETERMINATION OF THE CHIRALITIES OF ISOLATED CARBON NANOTUBES DURING SUPERPLASTIC ELONGATION PROCESS, стр. 051905-3).

3.U57757
Alonso, Bruno; Belamie, Emmanuel Chitin-Silica Nanocomposites by Self-Assembly //ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Volume: 49 Issue: 44 Pages: 8201-8204

Chitinases hydrolyze chitin, an insoluble linear polymer of N-acetyl-D-glucosamine (NAG)(n), into nutrient sources. Bacillus cereus NCTU2 chitinase (ChiNCTU2) predominantly produces chitobioses and belongs to glycoside hydrolase family 18. The crystal structure of wild-type ChiNCTU2 comprises only a catalytic domain, unlike other chitinases that are equipped with additional chitin binding and insertion domains to bind substrates into the active site. Lacking chitin binding and chitin insertion domains, ChiNCTU2 utilizes two dynamic loops (Gly-67-Thr-69 and Ile-106-Val-112) to interact with (NAG)(n), generating novel substrate binding and distortion for catalysis. Gln-109 is crucial for direct binding with substrates, leading to conformational changes of two loops with a maximum shift of similar to 4.6 angstrom along the binding cleft. The structures of E145Q, E145Q/Y227F, and E145G/Y227F mutants complexed with (NAG)(n) reveal (NAG)(2), (NAG)(2), and (NAG)(4) in the active site, respectively, implying various stages of reaction: before hydrolysis, E145G/Y227F with (NAG)(4); in an intermediate state, E145Q/Y227F with a boat-form NAG at the -1 subsite, -1-(NAG); after hydrolysis, E145Q with a chair form -1-(NAG). Several residues were confirmed to play catalytic roles: Glu-145 in cleavage of the glycosidic bond between -1-(NAG) and -1-(NAG); Tyr-227 in the conformational change of -1-(NAG); Asp-143 and Gln-225 in stabilizing the conformation of -1-(NAG). Additionally, Glu-190 acts in the process of product release, and Tyr-193 coordinates with water for catalysis. Residues Asp-143, E145Q, Glu190, and Tyr-193 exhibit multiple conformations for functions. The inhibitors zinc ions and cyclo-(L-His-L-Pro) are located at various positions and confirm the catalytic-site topology. Together with kinetics analyses of related mutants, the structures of ChiNCTU2 and its mutant complexes with (NAG)(n) provide new insights into its substrate binding and the mechanistic action.

4.U03117
Applied Physics Letters (USA). 2010 г., т. 97, N 3, (RECTIFICATION IN THREE-TERMINAL GRAPHENE JUNCTIONS A. Jacobsen, I. Shorubalko , стр. 032110-3).

5.U15453
By: Hsieh, Yin-Cheng; Wu, Yue-Jin; Chiang, Tzu-Ying; et al. //Crystal Structures of Bacillus cereus NCTU2 Chitinase Complexes with Chitooligomers Reveal Novel Substrate Binding for Catalysis A CHITINASE WITHOUT CHITIN BINDING AND INSERTION DOMAINS . Volume: 285 Issue: 41 Pages: 31603-31615 Published: OCT 8 2010

Chitinases hydrolyze chitin, an insoluble linear polymer of N-acetyl-D-glucosamine (NAG)(n), into nutrient sources. Bacillus cereus NCTU2 chitinase (ChiNCTU2) predominantly produces chitobioses and belongs to glycoside hydrolase family 18. The crystal structure of wild-type ChiNCTU2 comprises only a catalytic domain, unlike other chitinases that are equipped with additional chitin binding and insertion domains to bind substrates into the active site. Lacking chitin binding and chitin insertion domains, ChiNCTU2 utilizes two dynamic loops (Gly-67-Thr-69 and Ile-106-Val-112) to interact with (NAG)(n), generating novel substrate binding and distortion for catalysis. Gln-109 is crucial for direct binding with substrates, leading to conformational changes of two loops with a maximum shift of similar to 4.6 angstrom along the binding cleft. The structures of E145Q, E145Q/Y227F, and E145G/Y227F mutants complexed with (NAG)(n) reveal (NAG)(2), (NAG)(2), and (NAG)(4) in the active site, respectively, implying various stages of reaction: before hydrolysis, E145G/Y227F with (NAG)(4); in an intermediate state, E145Q/Y227F with a boat-form NAG at the -1 subsite, -1-(NAG); after hydrolysis, E145Q with a chair form -1-(NAG). Several residues were confirmed to play catalytic roles: Glu-145 in cleavage of the glycosidic bond between -1-(NAG) and -1-(NAG); Tyr-227 in the conformational change of -1-(NAG); Asp-143 and Gln-225 in stabilizing the conformation of -1-(NAG). Additionally, Glu-190 acts in the process of product release, and Tyr-193 coordinates with water for catalysis. Residues Asp-143, E145Q, Glu190, and Tyr-193 exhibit multiple conformations for functions. The inhibitors zinc ions and cyclo-(L-His-L-Pro) are located at various positions and confirm the catalytic-site topology. Together with kinetics analyses of related mutants, the structures of ChiNCTU2 and its mutant complexes with (NAG)(n) provide new insights into its substrate binding and the mechanistic action.

6.U41439
Chang, Yonghui; Zhang, Lei; Ying, Hanjie; et al. Desulfurization of Gasoline using Molecularly Imprinted Chitosan as Selective Adsorbents // APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY Volume: 160 Issue: 2 Pages: 593-603 Published: JAN 2010

For desulfurization of gasoline, novel chitosan-based molecularly imprinted polymer (MIP) was prepared by cross-linking chitosan with epichlorohydrin in the presence of dibenzothiophene (DBT) as the template. The influence of cross-linking ratio on the specific adsorption was evaluated. The effects of the types and the amounts of porogen on selectivity of the chitosan MIP were also examined. Results showed that MIP has a higher recognition property to DBT. The maximum rebinding capacities of the MIP reached 22.69 mg g(-1) in the model solution. The adsorption behaviors of the MIP including adsorption kinetics, isotherms, and thermodynamic parameters were investigated and the experimental data agreed well with the Langmuir model. The dynamical adsorption behaved in first-order kinetics. Negative values for the Gibbs free energy showed that the adsorptions were spontaneous processes. The MIP was further used to selectively adsorb organosulfur from gasoline.

7.U43538
Dash, Mamoni; Ferri, Marcella; Chiellini, Federica Synthesis and characterization of semi-interpenetrating polymer network hydrogel based on chitosan and poly(methacryloylglycylglycine) // MATERIALS CHEMISTRY AND PHYSICS Volume: 135 Issue: 2-3 Pages: 1070-1076 Published: AUG 15 2012

Objective of the present work was the development of a strategy for the synthesis of semi-interpenetrating networks (semi-IPN) based on chitosan and poly(methacrylamide) under physiological conditions. Free radical polymerization of methacryloylglycylglycine (MAGG) in the presence of chitosan and ethylene glycol dimethacrylate as the crosslinker was performed. Chitosan and poly(MAGG) hydrogels having different composition and amount of crosslinker were prepared. The presence of the two polymeric components in the polymer bulk was confirmed by fourier transform infrared spectroscopy (FTIR); thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to further substantiate the structural feature of the semi-IPN hydrogels. Finally, degradation behavior promoted by lysozyme demonstrated that there was 60%, 68% and 76% of degradation of the semi-IPN hydrogel with 8%, 4% and 2% of crosslinker respectively in 28 days. The preliminary investigations of the prepared materials suggest their suitability for applications in tissue engineering and controlled release of bioactive agents. (C) 2012 Elsevier B.V. All rights reserved.

8.U17853
Du, J. F.; Bai, Y.; Chu, W. Y.; et al. Synthesis and Performance of Proton Conducting Chitosan/NH4Cl Electrolyte // JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS Volume: 48 Issue: 3 Pages: 260-266 Published: FEB 1 2010

The polymer electrolytes based on chitosan and ammonium chloride were prepared by solution casting technique and the properties were studied. The addition of ammonium chloride results in: (1) the enhancement of the amorphous nature of the polymer electrolytes; (2) the shift of the absorption bands of amino group at 1566 cm(-1) and the carbonyl group at 1640 cm(-1) towards lower wave number, and the appearance of a new absorption band at 1759 cm(-1); (3) a decrease of the glass transition temperature. The 20 wt% ammonium chloride doped polymer electrolyte has the best room temperature electric property, the lowest activation energy and the highest ionic conductivity. Placing the as-prepared polymer electrolyte in a dryer is adverse for the sample's moisture content, and results in higher activation energy and lower ionic conductivity. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48:260-266, 2010

9.U17853
Du, J. F.; Bai, Y.; Chu, W. Y.; et al. The Structure and Electric Characters of Proton-Conducting Chitosan Membranes with Various Ammonium Salts as Complexant //JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS Volume: 48 Issue: 8 Pages: 880-885 Published: APR 15 2010

The structural and electric properties of chitosan electrolytes doped by three different ammonium salts [CH(3)COONH(4), NH(4)Cl, and (NH(4))(2)SO(4)] were discussed. The chitosan electrolytes were prepared by solution casting technique. The results show that the addition of ammonium salts leads to: The formation of complexation between ammonium salts and chitosan matrix, the destruction of crystal forms, and the enhancement of amorphous nature. With the rise of salt content, both the glass transition temperature and the activation energy show a "V"-type trend, whereas the conductivity exhibits a reverse trend. For different ammonium salts, the electric properties of the chitosan electrolyte are different due to the Coulomb force between anion of salts and functional groups. The CH(3)COONH(4) doped chitosan electrolyte exhibits the optimum electric properties, whereas those of (NH(4))(2)SO(4) doped chitosan electrolyte are worst. The chitosan electrolyte doped with 40 wt % CH(3)COONH(4) has the lowest glass transition temperature of 369 K, the lowest activation energy of 0.19 eV, and the highest ionic conductivity of 2.87 x 10(-4) S cm(-1) at room temperature. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 880-885, 2010

10.U53243
Ehrlich, Hermann; Simon, Paul; Carrillo-Cabrera, Wilder; et al. Insights into Chemistry of Biological Materials: Newly Discovered Silica-Aragonite-Chitin Biocomposites in Demosponges //CHEMISTRY OF MATERIALS Volume: 22 Issue: 4 Pages: 1462-1471 Published: FEB 23 2010

Biological materials are a rewarding area of modern materials science, yielding both evolutionary insights and inspiration for biomimetic research. In particular, biocomposite structures are valuable sources of novel structures with unusual chemical properties, and they are very informative for the mechanisms of biomineralization. Here we describe a unique biocomposite of amorphous silica, crystalline aragonite, and chitin from species of the order Verongida, a group of marine sponges. The structures have been analyzed with a diverse suite of techniques, revealing a chitinous template for siliceous overgrowth containing aragonite-based crystal aggregates. Sponge chitin is an example of a specific template where two minerals in amorphous and crystalline forms are formed together with an organic molecule.

11.U58317
Huang, Yuping; Yu, Hailong; Guo, Liang; et al. Structure and Self-Assembly Properties of a New Chitosan-Based Amphiphile //JOURNAL OF PHYSICAL CHEMISTRY B Volume: 114 Issue: 23 Pages: 7719-7726 Published: JUN 17 2010

A new chitosan-based amphiphile, octanoyl-chitosan-polyethylene glycol monomethyl ether (acylChitoMPEG), has been prepared using both hydrophobic octanoyl and hydrophilic polyethylene glycol monomethyl ether (MPEG) substitutions. The success of synthesis was confirmed by Fourier transform infrared (FT-IR) and (1)H NMR spectroscopy. The synthesized acylChitoMPEG exhibited good solubility in either aqueous solution or common organic solvents such as ethanol, acetone, and CHCl(3). The self-aggregation behavior of acylChitoMPEG in solutions was studied by a combination of pyrene fluorescence technique, dynamic light scattering, atomic force microscopy, and small-angle X-ray scattering (SAXS). The critical aggregation concentration (CAC) and hydrodynamic diameter were found to be 0.066 mg/mL and 24.4 nm, respectively. SAXS results suggested a coiled structure of the triple helical acylChitoMPEG backbone with the hydrophobic moieties hiding in the center of the backbone, and the hydrophilic MPEG chains surrounding the acylChitoMPEG backbone in a random Gaussian chain conformation. Cytotoxicity results showed that acylChitoMPEG exhibited negligible cytotoxicity even at concentrations as high as 1.0 mg/mL. All results implied that acylChitoMPEG has the potential to be used for biological or medical applications.

12.U15222
Journal of Applied Electrochemistry (GBR). 1999 г., т.29, N 5, ( Microstructural characterization and corrosion resistance of Ni-Zn-P alloys electrolessly deposited, стр. 637-645).

13.U60694
Lavric, Pavla Krizman; Warmoeskerken, Marijn M. C. G.; Jocic, Dragan Functionalization of cotton with poly-NiPAAm/chitosan microgel. Part I. Stimuli-responsive moisture management properties //CELLULOSE Volume: 19 Issue: 1 Pages: 257-271 Published: FEB 2012

Stimuli-responsive microgel, based on synthetic polymer (poly-NiPAAm) and biopolymer (chitosan), was incorporated onto cotton fabric surface by pad-dry-cure method using 1,2,3,4-butanetetracarboxylic acid (BTCA) as crosslinker. In order to assess the moisture management properties of cotton functionalized with responsive microgel, the effects of temperature, relative humidity and concentration of microgel on water vapour transmission rate (WVTR) and moisture content (MC) were quantified. Since the use of experimental design is considered as a highly attractive feature in dealing with experiments and variables of this nature, the effects were quantified by using a central composite design. The regression equations obtained from the statistical analysis allowed the prediction of WVTR and MC at different ambient conditions. Material properties such as crease recovery and whiteness were also measured. The results indicate that both relative humidity and temperature significantly influence studied responses (WVTR and MC), showing that good perspiration can be achieved at lower humidity levels and at higher temperatures. The observed phenomena are attributed to controlled expansion (or contraction) of the surface incorporated microgel, which acts as a sensor of temperature and as a valve to regulate the water vapour permeability of functionalized cotton.

14.U07758
Li, Puwang; Wang, Yichao; Zeng, Fanbo; et al. Synthesis and characterization of folate conjugated chitosan and cellular uptake of its nanoparticles in HT-29 cells // CARBOHYDRATE RESEARCH Volume: 346 Issue: 6 Pages: 801-806 Published: MAY 1 2011

Chitin, a polymer of N-acetylglucosamine (GlcNAc), is noted as the second most abundant biopolymer in nature. Chitin serves many functions for marine bacteria in the family Vibrionaceae ("vibrios"), in some instances providing a physical attachment site, inducing natural genetic competence, and serving as an attractant for chemotaxis. The marine luminous bacterium Vibrio fischeri is the specific symbiont in the light-emitting organ of the Hawaiian bobtail squid, Euprymna scolopes. The bacterium provides the squid with luminescence that the animal uses in an antipredatory defense, while the squid supports the symbiont's nutritional requirements. V. fischeri cells are harvested from seawater during each host generation, and V. fischeri is the only species that can complete this process in nature. Furthermore, chitin is located in squid hemocytes and plays a nutritional role in the symbiosis. We demonstrate here that chitin oligosaccharides produced by the squid host serve as a chemotactic signal for colonizing bacteria. V. fischeri uses the gradient of host chitin to enter the squid light organ duct and colonize the animal. We provide evidence that chitin serves a novel function in an animal-bacterial mutualism, as an animal-produced bacterium-attracting synomone.

15.U01944
Li, Shanshan; Du, Dan; Huang, Jing; et al. One-step electrodeposition of a molecularly imprinting chitosan/phenyltrimethoxysilane/AuNPs hybrid film and its application in the selective determination of p-nitrophenol // ANALYST Volume: 138 Issue: 9 Pages: 2761-2768 Published: 2013

This paper presents the fabrication of a molecularly imprinting sol-gel hybrid film by the one-step electrodeposition of the constitutional individuals including chitosan (CS), phenyltrimethoxysilane (PTMS), in situ formed gold nanoparticles (AuNPs) and template p-nitrophenol (p-NP). The electrodeposition was triggered by applying an optimal potential at -0.30 V vs. SCE, leading to the formation of the p-NP imprinting CS/PTMS/AuNPs hybrid film on a glassy carbon electrode (GCE) with a roughly architectural and conductive nature, as revealed by scanning electron microscopy and electrochemical impedance analysis. The mechanism of the hybrid film formation was discussed accordingly. Upon complete removal of the template molecules assisted by cyclic voltammetry, the p-NP imprinted film modified electrode exhibited differential pulse voltammetric (DPV) responses to p-NP in a linear range from 3.0 x 10(-8) to 3.5 x 10(-4) M with a detection limit of 5.0 x 10(-9) M. The selectivity and reusability of the sensor was demonstrated by discriminating the p-NP response from its analogues and successive rebinding/debinding cycles, respectively. The methodology is extendable as a simple and general platform for developing hybrid film sensors for the specific determination of various electrochemically active species.

16.U60694
Lin, Man-Chin; Tai, Hung-Yin; Ou, Ti-Cheng; et al. Preparation and characterization of UV-sensitive chitosan for UV-cure with poly(ethylene glycol) dimethacrylate // CELLULOSE Volume: 19 Issue: 5 Pages: 1689-1700 Published: OCT 2012

In this study, gel membranes of chitosan-g-poly(ethylene glycol) dimethacrylate (CS-g-PEGDMA) with pH sensitive properties were synthesized without employing any photo-initiator and crosslinker. First, CS was endowed with UV-sensitive property by reaction with cinnamoyl chloride in methanesulfonic acid. The reaction mainly occurred on the hydroxyl groups of the pyranose unit, while most C-2 amino groups were protected. The substitution degree of cinnamoyl group was 0.98, while the protection efficiency of -NH2 was about 80 %. Upon UV-irradiation, initial free radicals were produced only along the cinnamoyl-modified CS chains, which induced the grafting of PEGDMA from the chitosan chains and eventually the crosslinking. Increasing the feeding amount of PEGDMA increased the grafting ratio as well as the crosslinking density. The T-g value decreased from 161 A degrees C for the pure chitosan to about 90 A degrees C for the CS-g-PEGDMA with a grafting ratio of 1.29. Two stages of degradation correspondent to the individual degradation of CS chains and the PEGDMA chains were observed for all CS-g-PEGDMA copolymers, demonstrating their nature of graft copolymers. The tensile mechanical properties of the CS-g-PEGDMA membranes were affected by the two opposing factors: inter-connected soft PEGDMA chains and crosslinking density; and the optimum properties were achieved when the grafting ratio was increased to about 0.80. By combining CS and PEGDMA components, these copolymer membranes thus have the potential to be used as biomedical membranes.

17.U01982
Ma, Pei Lian; Buschmann, Michael D.; Winnik, Francoise M. Complete Physicochemical Characterization of DNA/Chitosan Complexes by Multiple Detection Using Asymmetrical Flow Field-Flow Fractionation// ANALYTICAL CHEMISTRY Volume: 82 Issue: 23 Pages: 9636-9643 Published: DEC 1 2010

Complete Physicochemical Characterization of DNA/Chitosan Complexes by Multiple Detection Using Asymmetrical Flow Field-Flow Fractionation By: Ma, Pei Lian; Buschmann, Michael D.; Winnik, Francoise M. ANALYTICAL CHEMISTRY Volume: 82 Issue: 23 Pages: 9636-9643 Published: DEC 1 2010 Full Text NCBI View AbstractClose AbstractAsymmetrical flow field flow fractionation (AF4) coupled with UV-vis spectrophotometry, multiangle light scattering (MALS), and dynamic light scattering (DLS) detection was used to analyze dispersions of DNA/rhodamine B labeled chitosan (Ch-rho) complexes frequently used as gene delivery vectors The method yielded, in a single experiment, important characteris tics of the complexes, such as their hydrodynamic radius, size distribution, conformation, composition, and the amount of free Ch-rho in the dispersions Samples for analysis were obtained by varying experi mental parameters known to influence the transfection efficiency of DNA/chitosan complexes, including the DNA concentration at mixing (82-169 mu g/mL), the ratio of chitosan amino groups to DNA phosphate groups (3 <= N/P ratio 5 15), the chitosan molecular weight (10-76 kDa), and its degree of deacetylation In all preparations, DNA/Ch-rho complexes had hydrodynamic radii ranging from 15 to 160 nm Both the DNA concentration and the Ch-rho molecular weight Influence the size distribution of the complexes a greater fraction of large particles wag detected in dispersions prepared with the most concentrated DNA solution or the Ch rho of highest molar mass All dispersions contained free Ch-rho in solution The free Ch-rho content ranged from 53 to 92% of the total Ch rho concentration in dispersions prepared with N/P ratios from 3 to 15, respectively, implying that the N/P ratio of the complexes ranged from 1 3 to 1 6 in all samples The accuracy of the free Ch-rho determination by AF4/UV-vis/MALS+DLS was confirmed by an in dependent method involving (1) ultracentrifugation of the dispersions prepared with unlabeled chitosan and (2) analysis of the supernatant by the Orange II dye depletion method This study demonstrates the ability of AF4/UV-vis/MALS+DLS to provide a complete physicochemical characterization of DNA/polycation complexes used in nonviral gene deliveryTimes Cited: 6 (from Web of Science Core Collection)

18.U03047
Mandel, Mark J.; Schaefer, Amy L.; Brennan, Caitlin A.; et al. Squid-Derived Chitin Oligosaccharides Are a Chemotactic Signal during Colonization by Vibrio fischeri // APPLIED AND ENVIRONMENTAL MICROBIOLOGY Volume: 78 Issue: 13 Pages: 4620-4626 Published: JUL 2012

Chitin, a polymer of N-acetylglucosamine (GlcNAc), is noted as the second most abundant biopolymer in nature. Chitin serves many functions for marine bacteria in the family Vibrionaceae ("vibrios"), in some instances providing a physical attachment site, inducing natural genetic competence, and serving as an attractant for chemotaxis. The marine luminous bacterium Vibrio fischeri is the specific symbiont in the light-emitting organ of the Hawaiian bobtail squid, Euprymna scolopes. The bacterium provides the squid with luminescence that the animal uses in an antipredatory defense, while the squid supports the symbiont's nutritional requirements. V. fischeri cells are harvested from seawater during each host generation, and V. fischeri is the only species that can complete this process in nature. Furthermore, chitin is located in squid hemocytes and plays a nutritional role in the symbiosis. We demonstrate here that chitin oligosaccharides produced by the squid host serve as a chemotactic signal for colonizing bacteria. V. fischeri uses the gradient of host chitin to enter the squid light organ duct and colonize the animal. We provide evidence that chitin serves a novel function in an animal-bacterial mutualism, as an animal-produced bacterium-attracting synomone.

19.U55484
Martins, Ana M.; Alves, Catarina M.; Kasper, F. Kurtis; et al. Responsive and in situ-forming chitosan scaffolds for bone tissue engineering applications: an overview of the last decade // JOURNAL OF MATERIALS CHEMISTRY Volume: 20 Issue: 9 Pages: 1638-1645 Published: 2010

The use of bioabsorbable polymeric scaffolds is being investigated for use in bone tissue engineering applications, as their properties can be tailored to allow them to degrade and integrate at optimal rates as bone remodelling is completed. The main goal of this review is to highlight the "intelligent" properties exhibited by chitosan scaffolds and their use in the bone tissue engineering field. To complement the fast evolution of the bone tissue engineering field, it is important to propose the use of responsive scaffolds and take advantage of bioinspired materials and their properties as emerging technologies. There is a growing interest and need for new biomaterials, such as "smart"/responsive materials with the capability to respond to changes in the in vivo environment. This review will provide an overview of strategies that can modulate bone tissue regeneration by using in situ-forming scaffolds.

20.U46930
Nuraje, Nurxat; Asmatulu, Ramazan; Cohen, Robert E.; et al. Durable Antifog Films from Layer-by-Layer Molecularly Blended Hydrophilic Polysaccharides // LANGMUIR Volume: 27 Issue: 2 Pages: 782-791 Published: JAN 18 2011

Mechanically durable, long-lasting antifog coatings based on polysaccharides were developed using a layer-by-layer (LBL) assembly process. The unique properties of these coatings are a result of a molecular-level blending of the polysaccharides, with multilayers containing chitosan and carboxymethyl cellulose providing the best overall properties. The antifog properties resulted from a strong interaction between the polar and H-bonding elements of the assembled polymers and water molecules and the concomitant formation of thin films of water. Environmental scanning electron microscopy (ESEM) studies confirmed that fogging coatings are decorated with light scattering, micrometer-sized droplets of water whereas antifogging coatings remain droplet free. To improve the mechanical durability of the multilayer films on substrates, the surface was modified via self-assembly of epoxy-functionalized silane molecules. Cross-linking chemistry was then applied to improve the mechanical robustness of the LBL films on various surfaces. These films were characterized using several techniques: optical profilometery (PL), spectroscopic ellipsometry (EL), contact angle goniometry (CA), and atomic force microscopy (A FM). The antifog properties of the films were evaluated by several tests under different environmental conditions. This work demonstrates that the unique water-adsorbing properties of polysaccharides can be exploited to create permanent antifog properties, which may be useful for various applications.

21.U46930
Rivas-Araiza, Rocio; Alcouffe, Pierre; Rochas, Cyrille; et al. Micron Range Morphology of Physical Chitosan Hydrogels // LANGMUIR Volume: 26 Issue: 22 Pages: 17495-17504 Published: NOV 16 2010

Physical chitosan hydrogels are potential biomaterials for several biomedical applications, such as wound healing. tissue repair, and drug delivery. Controlling the microstructural organization of chitosan gels is one of the keys for monitoring the physical, mechanical, and biological properties. As a result, the main objective of the present work was to explore the microstructural organization of chitosan hydrogels in relation with the processing conditions of gelation. For this purpose, different gelation routes were studied, that is, chitosan solution neutralization of an aqueous or hydroalcoholic solution and neutralization of an alco-gel. Overall, the resulting morphology idler processing was determined by the medium viscosity during neutralization and the nature and concentration of the base. The effect of these processing parameters on the morphology was evaluated mainly through small angle light scattering (SALS) measurements including in situ measurements during chitosan neutralization. As a result, we reported different bulk microstructures consisting in 200-400 nm aggregates (primary particles) agglomerated into micrometer range clusters or arranged into more organized structures, that is, forming microchannels (4-6 mu m). We thus established a qualitative and quantitative relation between supramolecular morphology and gelation conditions of chitosan hydrogels.

22.U4705X
Saranathan, Vinodkumar; Osuji, Chinedum O.; Mochrie, Simon G. J.; et al. Structure, function, and self-assembly of single network gyroid (I4(1)32) photonic crystals in butterfly wing scales //PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Volume: 107 Issue: 26 Pages: 11676-11681 Published: JUN 29 2010

Complex three-dimensional biophotonic nanostructures produce the vivid structural colors of many butterfly wing scales, but their exact nanoscale organization is uncertain. We used small angle X-ray scattering (SAXS) on single scales to characterize the 3D photonic nanostructures of five butterfly species from two families (Papilionidae, Lycaenidae). We identify these chitin and air nanostructures as single network gyroid (I4(1)32) photonic crystals. We describe their optical function from SAXS data and photonic band-gap modeling. Butterflies apparently grow these gyroid nanostructures by exploiting the self-organizing physical dynamics of biological lipid-bilayer membranes. These butterfly photonic nanostructures initially develop within scale cells as a core-shell double gyroid (Ia3d), as seen in block-copolymer systems, with a pentacontinuous volume comprised of extracellular space, cell plasma membrane, cellular cytoplasm, smooth endoplasmic reticulum (SER) membrane, and intra-SER lumen. This double gyroid nanostructure is subsequently transformed into a single gyroid network through the deposition of chitin in the extracellular space and the degeneration of the rest of the cell. The butterflies develop the thermodynamically favored double gyroid precursors as a route to the optically more efficient single gyroid nanostructures. Current approaches to photonic crystal engineering also aim to produce single gyroid motifs. The biologically derived photonic nanostructures characterized here may offer a convenient template for producing optical devices based on biomimicry or direct dielectric infiltration.

23.U15256
Sharma, Manoj; Singh, Sukhvir; Pandey, O. P. Excitation induced tunable emission in biocompatible chitosan capped ZnS nanophosphors //JOURNAL OF APPLIED PHYSICS Volume: 107 Issue: 10 Article Number: 104319 Published: MAY 15 2010

Colloidal semiconductor nanomaterials exhibit color modulation which can be useful for various optoelectronic and biolabelling applications. Previous studies on CdSe and CdTe have shown tunable color modulation by varying the size of nanomaterials but toxicity of cadmium has created doubt for its end applications as biosensor. The recent work on ZnS: Mn(2+) doped semiconductor has shown some viability for biolabelling but for tunable behavior particles of different doping concentration needs to be synthesized. In the present work all the above problems were considered and viable solution has been given to use ZnS: Mn(2+) doped semiconductor using chitosan as capping agent. Here we report deliberate color modulation for chitosan capped ZnS: Mn(2+) nanoparticles (NPs) synthesized in single step instead of many samples of different size. The tunable behavior is achieved by varying the excitation wavelength in same sample. Shifting of emission peak from dopant related emission at 590 nm (d states of Mn(2+)) to 481 nm defect related emission (Sulfur vacancy to Zn(2+)) and 421 nm (sulfur vacancy to valence band ) has been observed. The work illustrates coupling between Frenkel exciton in organic polymers with Wannier exciton in inorganic semiconductors which has been observed for the present nanophosphors. Synthesized chitosan capped ZnS: Mn(2+) NPs have been characterized by x-ray diffraction, high-resolution transmission electron microscopy, energy dispersive x-ray, and Fourier transform infrared for

24.U15773
Waraich, Sajjad M.; Hering, Britta; Burghard, Zaklina; et al. Fabrication and characterization of biocompatible nacre-like structures from alpha-zirconium hydrogen phosphate hydrate and chitosan //JOURNAL OF COLLOID AND INTERFACE SCIENCE Volume: 367 Pages: 74-82 Published: FEB 1 2012

Composite materials with an ordered layered structure resembling that of nacre were fabricated by layer-by-layer assembly making use of presynthesized a-zirconium hydrogenphosphate hydrate (ZrP) platelets and chitosan. These two biocompatible materials were chosen in view of possible applications in the biomedical field, e.g., as bone or joint replacement implants. The effect of different concentrations of the inorganic ZrP platelets and the organic components (chitosan) on the composite assembly and structure was investigated. A high concentration of chitosan (0.1 wt.%) resulted in a misalignment of the inorganic platelets, while at very low concentrations (0.001 wt.%), the substrate was not fully covered by the polymer, again leading to misalignment. Also, the concentration of the alpha-ZrP platelets affected the composite assembly and structure. The number of dipping cycles was varied between 70 and 220, yielding a maximum thickness of approximately 6 mu m. The pH value of the chitosan solution was also varied to investigate its influence on the composite assembly. The mechanical properties of the composites were tested with a nanoindenter. For samples prepared with the same number of dipping cycles, higher values of Young's modulus and hardness were obtained with improved alignment of the platelets in the samples. For samples prepared with 220 dipping cycles, a Young's modulus of 2.6 GPa and a hardness of 70 MPa were observed. Important general relationships are recognized between the preparation parameters. the degree of order within the nacre-like films and the resulting mechanical properties. (C) 201 1 Elsevier Inc. All rights reserved.

25.U6036X
Ye Wenting; Wu Di; Pan Xin; et al.Preparation of CTS Coatings Containing Calcium and Phosphorus on Titanium Surface by the Cathode Liquid Phase Plasma Technology// PLASMA SCIENCE & TECHNOLOGY Volume: 12 Issue: 5 Pages: 614-618

Full Text View AbstractClose AbstractChitosan (CTS) coatings contained calcium (Ca) and phosphorus (P) on titanium (Ti) surface are prepared by the cathode liquid phase plasma technology (CLPT), in a certain concentration electrolyte solution with selective additions of ammonium dihydrogen phosphate and calcium nitrate. It is indicated that the parameters for a stable discharge are voltage of 400 V, frequency of 100 Hz, duty cycle of 30% based on a large amount of experiment data. The morphology, structure and composition of the coated samples are studied by SEM, FTIR, XRD, XPS. The results demonstrate that the composite coatings are uniform, and some solid particles of inorganic salt containing calcium and phosphorus dispersed on the coatings. CA tests show that the samples treated by the liquid plasma became less hydrophilic. The variation of hydrophilicity on the CLPT treated titanium is attributed to the change of the function groups on the sample surface. Meanwhile, a possible formation mechanism of the composite coatings is discussed.Times Cited: 1 (from Web of Science Core Collection) Error: Please select at least one record using the checkboxes. Error: Record numbers need to be entered in sequential order. Error: The record numbers you entered do not exist in this set. Please check your numbers again. Error: Only 500 records at a time can be output. Error: We're sorry, you cannot output records beyond record 100000. Adjust the record numbers so they are not greater than 100000. Error: Record numbers may not contain special characters. Please select at least one record using the checkboxes. Our database does not contain records for any of the cited patents on this page. There is nothing to output. Error: Please enter a range. By clicking OK, I certify that I have authored the selected publication(s) or I have been authorized to administer the author's ResearcherID profile. Notice: This marked list contains more than 500 records. You have chosen to output the first 500 records. To output more than 500 records, use the 'Records X to Y' option and enter 501 to 1000, 1001 to 1500, and so on. Are you sure you want to continue outputting records 1 to 500? Notice: You can only order 35 records at a time. Please reduce the number of records selected and try again. You have exceeded the maximum number of marked records allowed (5000). You will need to save or export your existing marked records before you can add more.

26.U17834
Yuan, Weizhong; Zhao, Zhengda; Gu, Shuying; et al. Synthesis, Characterization, and Properties of Amphiphilic Chitosan Copolymers with Mixed Side Chains by Click Chemistry //JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY Volume: 48 Issue: 15 Pages: 3476-3486 Published: AUG 1 2010

Novel amphiphilic chitosan copolymers with mixed side chains of poly(epsilon-caprolactone) and poly(ethylene oxide) (CS-g-PCL/PEO) were successfully synthesized by "graft to" approach via click chemistry. The melting and crystallization behaviors and crystalline morphology of CS-g-PCL/PEO copolymers can be adjusted by the alteration of the feed ratio of PCL and PEO segments. CS-g-PCL/PEO copolymers revealed crystalline morphology different from that of linear alkynyl PCL and alkynyl PEO due to the influence of brush structure of copolymers and the mutual influence of PCL and PEO segments. The hydrophilicity of the CS copolymers can be improved and adjusted by the alteration of the composition of PCL and PEO segments. Moreover, the CS copolymers can self-assemble into spherical micelles in aqueous solution. Investigation shows that the size of the CS copolymer micelles increased with the increase of the content of hydrophobic PCL segments in copolymers, which indicated that the micellar behavior of the copolymers can be controlled by the adjustment of the ratio of PCL and PEO segments in copolymer. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3476-3486, 2010

27.U01982
Zhang, Xiaole; Niu, Hongyun; Pan, Yuanyuan; et al.Chitosan-Coated Octadecyl-Functionalized Magnetite Nanoparticles: Preparation and Application in Extraction of Trace Pollutants from Environmental Water Samples//ANALYTICAL CHEMISTRY Volume: 82 Issue: 6 Pages: 2363-2371 Published: MAR 15 2010

In the present study, chitosan-coated octadecyl-functionalized magnetite nanoparticles (Fe(3)O(4)-C(18)-chitosan MNPs) are synthesized and used as an adsorbent to extract trace analytes from environmental water samples. The magnetic nanoparticles, 20 nm in diameter, are of uniform size and have a high magnetic saturation value of 52 emu g(-1), which endue the adsorbent with a large surface area and convenience of isolation. The anionic pollutants, perfluorinated compounds (PFCs), are trapped by the octadecyl group of the interior hydrophobic layer. The positively charged chitosan polymer coating also contributes to PFC enrichment. At the same time, the coating improves the dispersibility of MNPs in aqueous solution and enhances the anti-interference ability of the adsorbent to natural organic macromolecules in complex samples by size exclusion or electrostatic repulsion. A liquid chromatography-tandem mass spectrometry system is employed in the determination of PFCs after preconcentration with the MNP adsorbent. The predominant factors affecting preconcentration are investigated and optimized, Under the selected conditions, concentration factors of 1000 are achieved by extracting the analytes from 500 mL of several environmental water samples and concentrating the eluants; to 0.5 mL with a nitrogen flow. The method detection limits obtained for perfluorooctanoic acid (PFOA), perfluorooctane-sulfonic acid (PFOS), perfluorononanoic acid (PFNA), perluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorododecanoic acid (PFDoDA), and perfluorotetradecanoic acid (PFTA) in Gaobeidian wastewater are 0.24, 0.093, 0.24, 0.14, 0.075, 0.24, and 0.17 ng L(-1), respectively. Recoveries of PFOA, PFOS, PFNA, PFDA, PFUnDA, PFDoDA, and PITA are in the ranges of 88-108%, 63-112%, 79-109%, 56-107%, 66-106%, 56-106%, and 66-103% for four spiked water samples with low relative standard deviation (2-8%), which indicates good method precision. The advantages of this novel adsorbent are high extraction efficiency, anti-interference, and convenient operation.

28.U01982
Zhang, Yongchao; Ji, Chang Electro-Induced Covalent Cross-Linking of Chitosan and Formation of Chitosan Hydrogel Films: Its Application as an Enzyme Immobilization Matrix for Use in a Phenol Sensor//ANALYTICAL CHEMISTRY Volume: 82 Issue: 12 Pages: 5275-5281 Published: JUN 15 2010

We report a novel electrochemical method for making covalently cross-linked chitosan films on the surface of a screen printed carbon electrode. In the presence of a freely diffusing ruthenium complex, Ru(bpy)(2)Cl(2), soluble chitosan becomes irreversibly cross-linked in response to a reducing potential and subsequently deposits on the electrode surface to form a hydrogel film which shows robustness in harsh acidic conditions. The cross-linked chitosan film presents excellent ability to facilitate the diffusion and electron transfer process of the negatively charged redox couple [Fe(CN)(6)](3-)/[Fe(CN)(6)](4-) at the electrode surface, while its impact on the positively charged redox couple [Ru(NH(3))(6)](2+)/[Ru(NH(3))(6)](3+) is minimal. By covalently immobilizing the enzyme tyrosinase in a preformed cross-linked chitosan film via a similar mechanism, a sensitive phenol sensor is constructed with a broad dynamic range. The potential advantages of this method are also discussed

29.U46930
Zheng, Jia N.; Xie, Hong G.; Yu, Wei T.; et al.Chitosan-g-MPEG-Modified Alginate/Chitosan Hydrogel//Langmuir (The ACS Journal of Surfaces and Colloids)(USA). 2010 г., т. 26, N 22,стр.17156-17164

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