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The modulus of traditional biomedical hydrogels increases exponentially meditated by dehydration-stiffing mechanism, which leads to the failure of interface matching between hydrogels and soft tissue wounds. It is found in the study that the dual-solvent gels exhibit dehydration-toughening mechanism with the slowly increasing modulus that are always match the soft tissue wounds. Therefore, dual-solvent glycerol hydrogels (GCFe n-gly DGHs) are prepared with hydrophobically modified catechol chitosan (hmCSC) and gelatin based on the supramolecular interactions. GCFe n-gly DGHs exhibit excellent water retention capacity with a total solvent content exceeding 80%, permanent skin-like modulus within a range of 0.45 to 4.13 kPa, and stable photothermal antibacterial abilities against S, aureus, E. coli, as well as MRSA. Infectious full-thickness rat skin defect model and tissue section analysis indicate that GCFe n-gly DGHs are able to accelerate infectious wound healing by alleviating the inflammatory response, promoting granulation tissue growth, re-epithelialization, collagen deposition, and vascular regeneration. As a result, GCFe n-gly DGHs is expected to become the next-generation biological gel materials for infectious wound treatment., (© 2024 Wiley‐VCH GmbH.)

In recent years, natural polymer-based electrospun fibers (EFs) with huge specific surface area, good biocompatibility, and biological activity obtained from electrospinning process exhibit tremendous vitality in the field of biomedical areas. Herein, the parameters of electrospinning from two perspectives, polymer solution such as solvent, polymeric relative molecular mass, concentration, viscosity, and conductivity of the solution, and electrospinning process such as spinning voltage, spinning flow rate, needle tip to collector distance, temperature, and humidity are first detailed. Next, the raw materials consisting of polysaccharides such as cellulose, hyaluronic acid, alginate, and chitosan as well as proteins such as collagen, gelatin, silk fibroin, and keratin are summarized. The preparation method and related characteristics of EFs with multistage structures such as porous, core-shell, Janus, bamboo-like and other structures are introduced. The biomedical applications of these natural polymer-based EFs mainly including tissue engineering, drug sustained release, wound dressings, and biomedical sensors are systematically recapitulated. Finally, the outlook on natural EFs is further proposed., (© 2022 Wiley-VCH GmbH.)

Unfortunately hemorrhage and its complications (e.g. anemia, organ failure, and hypothermia) induced by traumatic injury, surgery, and disorders of bleeding play an all too familiar role in human morbidity and mortality. Therefore, it is difficult to overstate the importance of better understanding the role of polysaccharides in advanced hemostatic dressings (HDs). This review includes consideration of polysaccharide hemostatic dressing mechanism of action, relative efficacy, cost and safety. Polysaccharide-based HDs are widely used in management not only of external and internal bleeding but also of massive hemorrhage. These polysaccharide-based HDs have been shown to be effective in both compressible and non-compressible hemorrhage. Hemostatic dressings are designed with different principles depending on location and extent of injury. This review focuses on polysaccharide HD design and associated hemostatic mechanisms. It addresses current issues, challenges, and future perspectives., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Restricted by the rigid chain structure, chitosan-based materials are very fragile and easy to break up. Herein, a stable and positively charged chitosan/Ti 3 C 2 T x suspension was successfully constructed by adjusting mixing sequence, pH and ratio of chitosan to Ti 3 C 2 T x to prepare a multifunctional membrane (P-CM) with self-standing ability, good flexibility, biocompatibility, excellent photothermal antibacterial properties, and sensitive humidity sensing properties. In the first stage, protonated chitosan acted as sugar coatings was able to be encapsulated on the surface of Ti 3 C 2 T x nanosheets by electrostatic self-assembly, in turn achieving charge reversal of the nanoparticles. In the second stage, chitosan acted as molecular needles to suture the membrane formed by chitosan/Ti 3 C 2 T x particles via vacuum filtration (VAF) with the commercial flexible poly(vinylidene fluoride) (PVDF) membrane. The as-prepared P-CM membrane simultaneously solves the problem of insufficient flexibility of a single component chitosan membrane and the poor bonding between pure Ti 3 C 2 T x membranes and substrate membrane., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Amines monomers, N,N-dimethylaminoethyl methacrylate (DMAEMA), N,N-dimethylethanolamine (DMEA), 2-dimethylaminoethylamine (DMEDA) and N-methiyldiethanolamine (MDEA) were used to induce the formation of calcium carbonate (CaCO3) crystals on chitosan films, by using (NH4)2CO3 diffusion method at ambient temperature. The obtained CaCO3 particles were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and Energy dispersive spectroscopy (EDS). The influence of reaction variables, such as the additive concentration and their types were also investigated on the products. The morphologies of CaCO3 crystals, inter-grown in cube-shape, were controlled by DMAEMA and DMEA. It was observed that the morphologies of CaCO3 changed from the cube grown arms to massive calcite with a hole on the face by increasing the concentrations of DMEDA and MDEA. While the precipitation grew on chitosan film without any organic additive, only single cube-shaped crystals were obtained. By these results the possible mechanisms can be proposed that electronic movement of the groups on the monomer effected ions configuration and molecules absorbed on the exposed surface, resulted the change of the surface energy, which caused the change in the morphology of CaCO3., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Glucose-responsive systems are significant for self-regulated insulin delivery. The aim of this study was to assess the potential of genipin-crosslinked concanavalin A/GEA-chitosan microgels as a glucose-responsive insulin delivery system. A chitosan derivative (GEA-chitosan) was designed in this study as the polymer ligand of concanavalin A (Con A), which not only exhibits a strong affinity to Con A, but also could be directly crosslinked with Con A by genipin, thus avoiding the modification of Con A during an immobilization process. Glucose responsive microgels were fabricated by the reversed-phase emulsion crosslinking method. The in vitro release of insulin indicated that the insulin release was influenced by glucose concentrations, and a desired pulsatile release behavior was detected in response to stepwise glucose challenges for more than eight cycles. The release data were fitted well to an exponential model, without any significant influence of the surface effect. The released insulin was proved to remain active without destruction of the tertiary structure. The analysis of L929 cells viability suggested that these microgels possessed no in vitro cytotoxicity. The obtained genipin crosslinked Con A/GEA-chitosan microgels might be a potential candidate for self-regulated insulin delivery., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Photopolymerizable chitosan derivative was synthesized by chitosan and methyl acroloyl glycine (MAG). The chemical structures and physical properties were characterized by FT-IR, (1)H NMR, XRD and TGA. The thermal stability of chitosan derivative was lower than chitosan. The chitosan derivative was amorphous compared with the high degree crystallization of chitosan. The hydrogels were prepared based on chitosan derivative via photopolymerization with different concentrations of photoinitiator 2959. The surface of hydrogel showed porous network and the pore size distribution tended to become homogeneous with the increase of the concentration of 2959, while the swelling property decreased due to more crosslinking., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The core-shell structure nanofibers of poly(lactic acid)/chitosan with different weight ratios were successfully electrospun from homogeneous solution. The preparation process was more simple and effective than double-needle electrospinning. The nanofibers were obtained with chitosan in shell while poly(lactic acid) in core attributing to phase separation, which were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). The electrospun nanofibrous membrane was evaluated in vitro by using mouse fibroblasts (L929) as reference cell lines. Cell culture results indicated that these materials were good in promoting cell growth and attachment, thus they could be used for tissue engineering and wound healing dressing., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Chitosan nanoparticles and paclitaxel loaded chitosan nanoparticles were prepared by emulsification-crosslinking method in a W/O emulsion system, using glutaraldehyde as crosslinking agent. The mean diameter of chitosan nanoparticles decreased with increase of pH value of the reaction system from 4.5 to 6.5, and increased when the pH exceeded 6.5. Ultraviolet spectrum analysis showed that the largest loading efficiency and encapsulation efficiency could be 8.55% and 94.01%, respectively. In vitro drug release profile was also determined by ultraviolet spectrometry. MTT assays revealed that the blank chitosan nanoparticles had almost none toxicity, and cell culture was carried out accordingly., (Copyright © 2012 Elsevier B.V. All rights reserved.)

A novel water-soluble chitosan derivative, glucosyloxyethyl acrylated chitosan was successfully synthesized by Michael addition reaction of chitosan with glucosyloxyethyl acrylate (GEA), and the obtained glyco-chitosan derivative was characterized by FT-IR, (1)H NMR, elemental analysis, XRD, TG, DSC and SEM. The FT-IR and (1)H NMR results showed that GEA residues were grafted onto the amino group of chitosan. The degree of substitution (DS) was calculated by elemental analysis. XRD data revealed that the introduced saccharide moieties decreased the crystalline structure of chitosan. TG and DSC results demonstrated that the glucosyloxyethyl acrylated chitosan was less thermal stable than chitosan. This efficient synthetic method provided an approach of preparing water-soluble glyco-chitosan derivatives. The obtained derivatives would show stronger specific affinity of lectin than chitosan thus would have potential applications in biomaterials., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Novel biodegradable hydrogels by photocrosslinking macromers based on chitosan derivative are reported. Photocrosslinkable macromers, a water-soluble (methacryloyloxy) ethyl carboxyethyl chitosan were prepared by Michael-addition reaction between chitosan and ethylene glycol acrylate methacrylate. The macromers were characterized by Fourier transform infrared spectroscopy, (1)H NMR and (13)C NMR. Hydrogels were fabricated by exposing aqueous solutions of macromers with 0.1% (w/v) photoinitiator to UV light irradiation, and their swelling kinetics as well as degradation behaviors was evaluated. The results demonstrated that the degradation rates were affected strongly by crosslinking density. The hydrogel was compatible to Vero cells, not exhibiting significant cytotoxicity. Cell culture assay also demonstrated that the hydrogels were good in promoting the cell attachment and proliferation, showing their potential as tissue engineering scaffolds., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The efficient procedure to prepare novel water-soluble chitosan derivative was established by Michael addition reaction to introduce sodium allylsulfonate into the chitosan at mild condition. The chemical structure of the chitosan derivative was characterized by FT-IR, (1)H NMR and Elemental analysis. The degree of substitution (DS) was calculated by Elemental analysis. The chitosan derivative exhibited an excellent solubility in the distilled water. The physical properties were analyzed by XRD and TG. The XRD study indicated that the crystallinity of chitosan derivative decreased. The thermal analysis showed that chitosan derivative had lower thermal stability than chitosan., (Copyright © 2010 Elsevier B.V. All rights reserved.)

A novel chitosan derivative carrying the benzene group was synthesized by Michael reaction. The chemical structures of the compounds were characterized by FT-IR, UV-vis spectrometry, XRD, elemental analysis, and 1H NMR spectroscopy in detail. The degree of substitution (DS) of chitosan derivative was calculated by elemental analysis. The UV-vis results indicated that the derivatives had ultraviolet absorption at 265 and 273 nm. XRD analysis showed that the derivatives were amorphous. The derivatives could dissolve in water. Taking advantage of the known capacity of solubility and ultraviolet absorption, the chitosan derivatives opened new possibilities for use as a sunscreen., (Copyright 2010. Published by Elsevier B.V.)

Glucose-responsive systems are very useful for self-regulated insulin delivery. In this study, glucose-responsive composite microparticles based on chitosan, concanavalin A and dextran were prepared by first fabricating chitosan microparticles subsequently coupling concanavalin A via Schiff-base reaction and dextran layer via specific affinity. SEM, fluorescence microscope, XPS and TGA were used to characterize the morphology and composition of the microparticles. SEM results indicated that the microparticles could exist individually and in a spherelike shape. The fluorescence image showed that the microparticles were well dispersed with an average diameter of 2.5 microm. The XPS and TGA data confirmed the composite layers of the microparticles. Insulin could be loaded into the microparticles due to electrostatic and intermolecular interaction with high entrapment efficiency of 92.2% and loading capacity of 9.1%. The release profiles of insulin revealed that the insulin release was in response to the glucose concentration in the medium and the glucose sensitivity was reversible. The released insulin was proved to remain active through the whole process. The results suggest that this composite microparticle may be a promising system for self-regulated insulin delivery., (Copyright (c) 2009 Elsevier B.V. All rights reserved.)

Porous scaffolds composed of alginate (AG) and chitosan (CS) were fabricated by combining the formation of polyelectrolyte complex (PEC) with freeze-drying. The AG scaffold was used as a framework with uniformly distributed and interconnected pore structure. The chitosan or chitosan/hydroxyapatite (CS/HA) composite solution was introduced into the pores of AG scaffold to form PEC scaffolds. FT-IR, XRD and XPS analysis confirmed that CS or CS/HA was coated on the AG scaffold surface. Microstructure, porosity, mechanical strength and thermal stability of PEC scaffolds were also investigated. The AG-CS PEC scaffold and Ca2+ crosslinked AG scaffold showed smaller average pore diameter and lower porosity than those of uncrosslinked AG scaffold. Moreover, compared with Ca2+ crosslinked AG scaffold, AG-CS PEC scaffold exhibited higher mechanical strength and better thermal stability., (2009 Elsevier B.V. All rights reserved.)

N-Alkyled photo-polymeriable chitosan derivative (PEGDA-CS) was synthesized by Michael reaction of chitosan and polyethylene glycol diacrylate (PEGDA) under mild reaction conditions. The chemical structure and physical properties of PEGDA-CS were characterized by FT-IR, (1)H NMR, XRD and TG techniques. The degree of substitution (DS) of PEGDA-CS could be calculated from (1)H NMR. PEGDA-CS exhibited good solubility in distilled water. XRD analysis showed that PEGDA-CS was amorphous. TG results demonstrated that thermal stability of the derivate was lower than that of chitosan. Antimicrobial test showed that PEGDA-CS had the antimicrobial activity on Escherichia coli. It could photopolymerize under ultraviolet light with 2959 as initiator.

A series of hybrid hydrogels based on glycidyl methacrylated chitosan (CS-GMA) and N-isopropylacrylamide (NIPAAm) were designed and prepared via photopolymerization technology. The hydrogels were characterized by Fourier transform infrared (FT-IR), differential scanning calorimetry (DSC) and optical transmittance. The interior morphology of hydrogels was investigated by scanning electron microscopy (SEM). The swelling experiment results revealed that hybrid hydrogel exhibited combined pH and temperature sensitivities. Acid orange 8 (AO8) and 5-flurouracil (5-Fu) were selected as model drugs for examining their release from hydrogels. The results suggested that hydrogel composition and pH value of buffer solution had great influences on release profiles.

Biocompatible hydrogels based on water-soluble chitosan-ethylene glycol acrylate methacrylate (CS-EGAMA) and polyethylene glycol diamethacrylate (PEGDMA) were synthesized by photopolymerization. Characterization of morphology, weight loss, water state of hydrogel, pH-sensitivity and cytotoxicity were investigated by scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), X-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), swelling test and methylthiazolydiphenyl-tetrazolium bromide (MTT) assay. The results indicated that the hydrogels were sensitive to pH of the medium, no cytotoxicity for L929 and SW1353, satisfactory for the composite to be used in bioapplications.

Michael addition reaction of Chitosan (CS) and polyethylene glycol diacrylate (PEGDA) was carried out successfully in acidic solution. Films with CS/PEGDA weight ratios from 100/0 to 0/100 in 10% increments were analyzed by Fourier transform infrared (FTIR) spectroscopy, Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD). Additionally, the films were characterized by measuring mechanical property, swelling property. The potential application of the CS/PEGDA film as wound dressing material was evaluated in vitro by using mouse fibroblasts (L929) as reference cell lines, indirect cytotoxicity assessment indicated that CS/PEGDA films were nontoxic to L929 cell.

A biocomposite of hydroxyapatite (HAp) with electrospun nanofibrous scaffolds was prepared by using chitosan/polyvinyl alcohol (CS/PVA) and N-carboxyethyl chitosan/PVA (CECS/PVA) electrospun membranes as organic matrix, and HAp was formed in supersaturated CaCl2 and KH2PO4 solution. The influences of carboxylic acid groups in CECS/PVA fibrous scaffold and polyanionic additive poly(acrylic acid) (PAA) in the incubation solution on the crystal distribution of the HAp were investigated. Field-emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS), wide-angle X-ray diffraction (WAXD), and Fourier transform infrared (FTIR) were used to characterize the morphology and structure of the deposited mineral phase on the scaffolds. It was found that addition of PAA to the mineral solution and use of matrix with carboxylic acid groups promoted mineral growth and distribution of HAp. MTT testing and SEM imaging from mouse fibroblast (L929) cell culture revealed the attachment and growth of mouse fibroblast on the surface of biocomposite scaffold, and that the cell morphology and viability were satisfactory for the composite to be used in bioapplications.

Biocompatible carboxyethyl chitosan/poly(vinyl alcohol) (CECS/PVA) nanofibers were successfully prepared by electrospinning of aqueous CECS/PVA solution. The composite nanofibrous membranes were subjected to detailed analysis by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). SEM images showed that the morphology and diameter of the nanofibers were mainly affected by the weight ratio of CECS/PVA. XRD and DSC demonstrated that there was strong intermolecular hydrogen bonding between the molecules of CECS and PVA. The crystalline microstructure of the electrospun fibers was not well developed. The potential use of the CECS/PVA electrospun fiber mats as scaffolding materials for skin regeneration was evaluated in vitro using mouse fibroblasts (L929) as reference cell lines. Indirect cytotoxicity assessment of the fiber mats indicated that the CECS/PVA electrospun mat was nontoxic to the L929 cell. Cell culture results showed that fibrous mats were good in promoting the cell attachment and proliferation. This novel electrospun matrix would be used as potential wound dressing for skin regeneration.

ABSTRACT Core-shell structured PEO-chitosan nanofibers have been produced from electric field inducing phase separation. Chitosan, a positive charged polymer, was dissolved in 50 wt % aqueous acetic acid and the amino group on polycation would protonize, which would endow chitosan electrical properties. Chitosan molecules would move along the direction of the electric field under the electrostatic force and formed the shell layer of nanofibers. Preparation process of core -shell structure is quite simple and efficient without any post-treatment. The core-shell structure and existence of chitosan on the shell layer were confirmed before and after post-treatment by TEM and further supported by SEM, FTIR, XRD, DSC, and XPS studies. Blending ratio of PEO and chitosan, molecular weight of chitosan for the mobility of chitosan are thought to be the key influence factors on formation of core-shell structure. Drug release studies show that the prepared core-shell structure nanofibers has a potential application in the biomedical fields involving drug delivery. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2298-2311 [ABSTRACT FROM AUTHOR]

The present work was focused on the preparation and characterization of polyelectrolyte complex (PEC) fibers based on the natural oppositely charged biopolymers, chitosan and sodium hyaluronate, via a freeze-drying method. The physical structure and chemical properties of the freeze-dried fibers were characterized by means of Fourier transform infrared spectroscopy (FT-IR), solid-state 13C nuclear magnetic resonance (13C-NMR) and X-ray diffraction (XRD). The morphology, size, and surface structure of the freeze-dried PEC fibers were observed by means of scanning electron microscopy (SEM). An indirect in vitro cytotoxicity test showed the extracts of fibers had no significant effects on cell viability. Moreover, an in vitro cytocompatibility test exhibited cell population and spreading tendency, suggesting the fibers were non-toxic to L929 cells. All the results indicated that such freeze-dried PEC fibers might have potential applications in tissue engineering scaffolds. [ABSTRACT FROM AUTHOR]

The article discusses an experiment which investigated the photocrosslinking of electrospun fibers chitosan/polyvinyl alcohol (CS/PVA). Poly(ethyleneglycol)-600-dimethacrylate (PEGDMA) was used as the photocrosslinking agent while 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone (HEPK) was used as photoinitiator. Increasing the content of PEGDMA/HEPK improved the water resistance and decreased the swelling ratio of the photocrosslinked nanofibers.

The article presents a study which investigates the characterization of nitrogen (N)-alkylated chitosan derivates. The study synthesized the said chitosan in water which contains acetic acid by the Michael addition reaction. The discussion of various methods used in the study such as fourier transform infrared (FTIR) spectroscopy, antibacterial activity tests, and X-ray diffraction (XRD) were also included. The XRD analysis reveals that chitosan derivatives were amorphous.

Abstract: This study is aimed to develop porous poly(methyl methacrylate) (PMMA) as a potential bone substitute via a facile fabrication method. Composites consisting of water-soluble chitosan oligosaccharide (CSO) and PMMA were prepared by combining freeze-drying with radical polymerization. Open porous PMMA with controlled porosities were obtained after the CSO was extracted gradually from the composites. The CSO aqueous solutions with different concentrations were frozen and then freeze-dried to obtain interconnected porous framework. Methyl methacrylate with initiators and a crosslink agent was introduced into the porous framework and polymerized, resulting in two-continuous phase composites. The mechanical properties of the initial composites and porous materials after immersion in PBS for 8weeks were investigated. Dynamic mechanical analysis was conducted to study the mechanical strength of the composite, compared with bulk PMMA. Porosity and morphology of porous PMMA were studied using the liquid displacement method and scanning electron microscopy, respectively. Thermogravimetric analysis indicated that composite exhibited better thermal stability than bulk PMMA. The composites became porous materials after extracting bioactive CSO component. The mechanical properties of porous materials were closer to those of cancellous bone. The generation of pores using CSO seems to be a promising method to prepare porous PMMA as a potential bone substitute. [Copyright &y& Elsevier]

Abstract In order to improve the removal ability of chitosan (CS) to heavy metal ions, in this study, rich amino-functionalized CS electrospun membranes have been prepared. During the efficient synthesis, poly (glycidyl methacrylate) (PGMA) and polyethylenimine (PEI) were sequentially grafted on the surface of CS electrospun membrane. The success of introduction of amino-group on the CS were confirmed by X-ray diffractometer (XRD), attenuated total reflection-fourier transform infrared (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). The ability of remove heavy metal ions (Cr(VI), Cu(II) and Co(II)) of the as-prepared membrane (CS-PGMA-PEI) was investigated. The adsorption equilibrium of the heavy metal ion solutions was rapidly established in 60 min. Adsorption kinetics analysis reveals that the adsorption process of CS-PGMA-PEI electrospun membrane was dominated by a Pseudo-second-order model. Its adsorption isotherm can be described by the Langmuir model. The maximum adsorption capacities calculated by Langmuir model were 138.96, 69.27 and 68.31 mg g −1 for Cr(VI), Cu(II) and Co(II), respectively. The adsorption ability of CS-PGMA-PEI electrospun membrane toward metal ions was found in an order of Cr(VI) > Cu(II) > Co(II). CS-PGMA-PEI membrane also exhibited a good reproducibility and stability. Our study may provide a way to synthesize membranes for water purification. Graphical abstract The PEI-grafted CS (named as CS-PGMA-PEI) electrospun membrane was demonstrated by the following steps: (1). In order to expose the amino groups on the surface of the chitosan, the CS/PEO electrospun membrane was immersed in water to remove the PEO; (2). Poly (glycidyl methacrylate) (PGMA) and polyethylenimine (PEI) were sequentially grafted onto the CS electrospun membrane by a ring-opening reaction of epoxy groups with amino groups to obtain PEI-immobilized CS membrane; (3). A series of batch adsorption experiments were carried out to determine the adsorption performance. Image 1 Highlights • The PEI-grafted chitosan electrospun membrane has been prepared. • The adsorption ability of CS-PGMA-PEI electrospun membrane is in an order of Cr(VI) > Cu(II) > Co(II). • The CS-PGMA-PEI electrospun membrane exhibited good regenerability and stability for heavy-metal removal. [ABSTRACT FROM AUTHOR]

Highlights: [•] Alginate/chitosan layer-by-layer composite coatings were prepared on titanium substrates via electrodeposition at room temperature [•] The thickness of the deposited chitosan layer and alginate was about 20μm and 10μm, respectively [•] Provides opportunities in the fabrication of functional coatings on titanium substrates. [ABSTRACT FROM AUTHOR]

Abstract: A highly porous chitosan nanofibers were obtained by electrospinning chitosan/polyethylene oxide (PEO) blend solutions and then removing PEO with water. The porous morphology of the nanofibers was observed by scanning electron microscopy. The porous nanofibers were soaked in 0.1wt% paclitaxel solution to load the cancer drug. Then a polyanion nature macromolecular hyaluronic acid (HA) was encapsulated on the chitosan polycation porous nanofibers by immersing the fibers into a 4wt% HA aqueous solution. Differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) were used to investigate the polymer formation and the interaction among two nature macromolecular and the cancer drugs. The paclitaxel release profiles of the encapsulated fibers in PBS were analyzed by UV–vis spectrophotometer. In vitro DU145 prostate cancer cells activities of the nanofibers were examined by MTT. Cell culture results showed that the PTX-loaded nanofibers mats were good in prohibiting the cell attachment and proliferation. These results strongly suggested that the chitosan/hyaluronic acid fibers had an effect of controlled release of paclitaxel and were suitable for postoperative chemotherapy of prostate cancers. [Copyright &y& Elsevier]

Abstract: Based on the principles of biomineralization, a calcium carbonate (CaCO3) and chitosan composite membrane was prepared by mineralized of calcium carbonate on chitosan/poly(vinyl alcohol) nanofibers under dynamic condition. The morphology and structure of membranes were characterized by scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. The results showed that the chitosan/poly(vinyl alcohol) nanofibers produced thin CaCO3 island crystals, which interlaced with the chitosan fiber not only on the surface of the membrane but also within the membrane. The crystals could develop into a continuous CaCO3 membrane on the fibers at latter stage of mineralization, the obtained crystals was mainly calcite type of CaCO3, and with small quantity of vaterite. MTT test and SEM imaging indicated that the attachment and growth of mouse fibroblast were well on the surface of CaCO3/chitosan/PVA composite membrane, and this composite has a good application prospect in the field of biomedical materials. [Copyright &y& Elsevier]

Abstract: A chitosan derivative carrying the benzene group was synthesized by the acylation reaction in the mild conditions. The chemical structures and physical properties of the compounds were characterized in detail. The chitosan derivatives were amorphous comparing with chitosan. The photopolymerization capability of chitosan derivative was also carried out by real-time infrared (RTIR) spectra, and it also has the own ability to photopolymer without photoinitiator under UV irradiation. The derivative had good ultraviolet absorption at 280nm and good solubility in organic solvents. [ABSTRACT FROM AUTHOR]

Abstract: Methoxy poly(ethylene glycol)-grafted chitosan (PEG-g-CS) was synthesized by mild Michael addition reaction of chitosan and methoxy polyethylene glycol monoacrylate. The chemical structure and degree of substitution (DS) of chitosan derivative were studied by FT-IR and 1H NMR. Blend nanofibers of PEG-g-CS and poly(ethylene oxide) (PEO) were successfully fabricated by electrospinning and characterized by SEM, XRD, DSC and TEM. SEM images showed when the mass ratio of PEG-g-CS/PEO ranged from 4/1 to 1/2, uniform ultrafine fibers could be fabricated. XRD and DSC results confirmed the crystalline microstructure of PEO component. The core–shell structure nanofibers were observed by TEM. Besides, water resistance of glutaraldehyde crosslinked nanofibers and organic solvent resistance of original nanofibers were also evaluated through morphology analysis. [ABSTRACT FROM AUTHOR]

Abstract: Injectable hydrogels were prepared from chitosan derivative (EGAMA-CS)/polyethylene glycol dimethacrylate (PEGDA)/N,N-dimethylacrylamide (DMMA) by photopolymerization. The morphology of the hydrogels was observed by scanning electron microscope (SEM). The relationship of double bond conversion with photopolymerization time was revealed by Real-time FTIR. The thermal behaviour of the hydrogels was investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The equilibrium swelling ratio was also evaluated. In addition, the potential use of the hydrogels as scaffolding materials for bone regeneration was evaluated in vitro with Human bone sarcoma cell (SW1353) as reference cell lines. Indirect cytotoxicity assessment of the hydrogels indicated that the EGAMA-CS/PEGDA/DMMA hydrogels was non-toxic to the SW1353 cell. Cell culture results showed that fibrous mats were good in promoting the cell attachment and proliferation. The photopolymerized hydrogels are promised for the applications in the biomaterials area as bone tissue engineering matrix. [Copyright &y& Elsevier]

Abstract: With the goal of obtaining photopolymerized hydrogels for use as tissue engineering scaffolds, a water-soluble (methacryloyloxy) ethyl carboxyethyl chitosan was prepared as a photopolymerizable prepolymer through Michael-addition reaction between chitosan and ethylene glycol acrylate methacrylate. N-substitution of chitosan was verified by both 1H NMR and 13C NMR The degree of N-substitution, measured via 1H NMR, was easily varied from 0.10 to 0.35 by varying the molar ratio of ethylene glycol acrylate methacrylate to chitosan. Using a Vero cell line, the water-soluble photocrosslinkable chitosan derivative was found to be noncytotoxic up to a concentration of 1.0mg/mL. The precursor was blended with D-2959 photoinitiator in solution, and UV-irradiated to create hydrogels. FTIR verified the nearly complete conversion of the double bonds in the gel. Indirect cytotoxicity assessment of the hydrogel indicated that the hydrogel was non-toxic to Vero cells. [Copyright &y& Elsevier]

Abstract: Acylated chitosan was synthesized by reaction of chitosan and stearoyl chloride. The chemical structures and physical properties of the prepared compounds were confirmed by Fourier transform infrared (FT-IR), 1H Nuclear Magnetic Resonance (1H NMR) spectroscopy, X-ray diffraction (XRD) and Thermogravimetric (TG) techniques. The degree of substitution (DS) was calculated by 1H NMR and ranged from 1.8 to 3.8. The synthesized compounds exhibited an excellent solubility in organic solvents. XRD analysis showed that they had high crystalline structure. TG results demonstrated that thermal stability of the prepared compounds was lower than that of chitosan, the weight loss decreased with increase of DS. This procedure could be a facile method to prepare organic-soluble chitosan derivatives. [Copyright &y& Elsevier]

Abstract: Semi-interpenetrating polymer network (semi-IPN) hydrogels were prepared by UV irradiation of water-soluble N-carboxylethyl chitosan (CECS) and 2-hydroxyethyl methacrylate (HEMA) aqueous solutions in the presence of D-2959 as photoinitiator. Hydrogels were characterized by using scanning electron microscopy (SEM), thermal gravimetric analysis (TGA) and X-ray diffractometry (XRD). SEM showed that semi-IPN hydrogels displayed porous surface and therefore had high surface area. XRD indicated that CECS/poly (HEMA) semi-IPN hydrogels had amorphous structure. The thermal stability and equilibrium degree of swelling improved obviously with increase of CECS content. Differential scanning calorimetry (DSC) indicated that free water content increased with increase of CECS content while bonded water content decreased. Cytotoxicity results suggested that semi-IPN hydrogels had good biocompatibility. From these preliminary evaluations, it is possible to conclude that these materials have potential applications in the biomedical field. [Copyright &y& Elsevier]

Abstract: N-Alkylated chitosan derivative was synthesized by Michael addition reaction of chitosan and hydroxyethylacryl. The chemical structure and physical properties of the chitosan derivatives were characterized by FT-IR, 1H NMR, XRD and DSC techniques. The 1H NMR results indicated that the degree of substitution (DS) was from 0.18 to 1.2. The chitosan derivatives exhibited an excellent solubility in distilled water. XRD analysis showed that the derivatives were amorphous. DSC results demonstrated that thermal stability of the derivatives was lower than that of chitosan and it decomposed around 226°C for hydroxyethylacryl-CS with DS higher than 1.05. The lysozyme enzymatic degradation results revealed that the chitosan derivatives had the ability to enzymatic degradation and the initial degradation rate of the chitosan derivatives was dependent on its molecular weight. The antimicrobial activity of the chitosan derivatives was decreased compared with that of chitosan, but it still had the ability of antimicrobial. [Copyright &y& Elsevier]

Abstract: Polyelectrolyte complex (PEC) fibers composed of two opposite charged natural biopolymers were prepared via electrospinning. The influence of PECs solution properties on the electrospinnability was investigated. The electrospinnability of PEC solution became poor as the increase of conductivity and viscosity, which was different with normal electrospinning process. Such novel phenomenon was considered as the result of complicate interaction among the two polyelectrolytes and solvent. The ratio of –COOH/-NH2 was calculated. DSC results proved that molecular level complex was formed in the PEC fibers. The PEC fibers will be expected as biomedical materials in tissue engineering. [Copyright &y& Elsevier]