Papers by Keyword: Chitosan (CS)

Abstract: Different chitosan carboxylic salts were successfully prepared via a simple way using chitosan and oxalic, fumaric, salicylic acid for the first time. The characterizations of the salts were evaluated by FT-IR, 13C NMR, 1H NMR, elemental analysis, XRD. The solution properties and moisture absorption-retention abilities of the salts were compared with chitosan. The result indicated that chitosan and carboxylic acid were combined with salt bond. The properties of the salts were related to the type of carboxylic acid added and the formation of salt bond. The water-solubility, wetting effect and moisture-retention absorption abilities of the salts were better than chitosan. They therefore have the potential to substitute for chitosan for easy use as coating in food preservation.

Abstract: Grafted chitosan(CTS) copolymer was synthesized by the aqueous solution polymerization method, using the ammonium persulfate as initiator graft, Acrylamide（AM）and methacrylamide trimethyl Ammonium Chloride (DMC) as the grafted monomer. The effects of reaction conditions on grafted copolymerization were studied. When the deacetylation degree of chitosan as raw material is 86%, the optimum reaction to produce CTS -AM-DMC ternary graft copolymers by first AM and then DMC sequence were obtained at [initiator] 0.08%, 50°Cand 3.5h.The structure of CTS-AM-DMC was characterized by FTIR and XRD. When the dosage of synthetic product is 0.3mg/L, the effect of flocculation on the papermaking wastewater is obvious better, which can make the light transmission up to 99%, and CODCr to 9mg/L.

Abstract: The acidfied sulfur-prevulcanized natural rubber (NR) latex was mixed with 1～20 parts per hundred rubber (phr) of a 2wt% solution of chitosan (CS) in 1wt% acetic acid, then cast to preapare a series of NR/CS semi-interpenetrating polymer network (semi-IPN) films; the NR/CS semi-IPN films were further treated with 0.5wt% glutaraldehyde（GA）solution for respectively 1, 3 and 6h to obtain NR/CS IPN films. The mechanical properties and swelling behavours in various media of water, toluene and reference olis of IRM901 and IRM 903 of these films were studied and compared with those pure sulfur-prevulcanized natural rubber latex (SNRL) film. Results showed that, NR/CS IPN films with better mechanical properties could be obained by treating the 24h-leached NR/CS semi-IPN films than by treating directly the unleached ones with 0.5wt% GA solution; the tear strength, 300% modulus, Shore A hardness, hydrophilicity and resistance to non-polar solvents and oil of the SNRL films increased with the incorporation of CS, while the NR/CS IPN films exhibited better than the NR/CS semi-IPN films, especially in tear strength enhancement; the tensile strength and elongation at break of NR/CS semi-IPN and IPN films gradually decreased with the increase in CS content. However, most of the elasticity of pure NR vulcanizate could be reserved, when the CS content was not greater than 15 phr.

Abstract: A new composite magnetic chitosan coated cotton (MSCC) fiber with 3-glycidyloxypropyltrimethoxysilane (GPTMS) as a crosslinking agent was prepared for the adsorption of C.I. Reactive red 194 from aqueous solution. The structure and morphology of MSCC fibers were analyzed by FTIR and SEM. The adsorption behavior of C.I. Reactive red 194 from aqueous solution onto MSCC fibers was investigated under various experimental conditions such as initial concentration of the dyes, temperature, pH and adsorb time. Experimental data indicated that the adsorption capacity of MSCC fibers on C.I. Reactive red 194 was higher in acidic rather than in basic solutions. A rise of temperature accelerates mass transfer of dyes into the MSCC fibers. The kinetics of the interactions was best described by pseudo-second-order mechanism.

Abstract: A kind of 1,8-naphthalimide derivative grafted onto Chitosan was synthesized with Chitosan, 4-bromo-N-(2-aminoethyl)-1,8-naphthalimide and 4-bromo-1,8- naphthalic anhydride via substitution and amidation. The structures of compounds was characterized by FT-IR．Thermal stability and fluorescence spectra of the target product were investigated. Compared with 4-bromo-N-(2-aminoethyl)-1,8-naphthalimide, the maximum fluorescent intensity of the 1,8-naphthalimide derivative grafted onto Chitosan was increased 1.25 folds.

Abstract: Effect of the dosage of flocculants on activated sludge dewatering is analyzed through the determination of sludge specific resistance to filtration．Sludge dewatering behaviors conditioned on PAC, CTS and composite flocculants have been compared. The results show all the conditioning agent have help to sludge dewatering .Compared with Polymeric aluminum , Chitosan(CTS) and PAC/CTS composite coagulant, the optimum coagulant with its optimum dosage is obtained .PAC/CTS can greatly reduce the sludge specific resistance and improves the sludge dewatering performance largely while the clarity of the filtrate was higher.

Abstract: The aim of this study is to evaluate the injectable cross-linked chitosan (CS) microparticles (MPs) to apply for biomedical applications specifically for bone regeneration. The CS MPs were fabricated by emulsification method and formed the cross-links between the amide groups in the CS and phosphate groups in the sodium tripolyphosphate (TPP) ionic cross-linking agent. The MPS were analyzed for morphology by Scanning Electron Microscope (SEM). The fabricated CS MPs were in the spherical shape with the size range of 20-100 m. These CS MPs were analyzed for biodegradation by immersing in phosphate buffered saline (PBS, pH = 7.4) at 37°C for 30 weeks. The biodegradation of CS MPs in PBS was initiated at week 25. Mesenchymal stem cells (MSCs) were harvested from the bone marrow of mice tibia and femurs. The MSC attachment on CS MPs was tested using LIVE/DEAD cell sassy with a Fluorescence Microscope. The murine MSCs attachment onto CS MPs at day 2 was confirmed by visualizing fluorescence images. The CS MPs were also analyzed for the injectability and retainability at the site using a subcutaneous injection in a rat model. The fabricated CS MPs possess injectability, biodegradability and biocompatibility. Therefore, these CS MPs have a great potential to apply for various biomedical applications including bone regeneration by injection.

Abstract: The biomineral-binding alendronate-chitosan conjugate (Scheme 1) was developed as a novel drug delivery system. Alendronate was conjugated to the hydroxyl groups of chitosan, thereby maintaining the amino groups of chitosan intact. By means of FT-IR and ¹H NMR, the characterization was conducted to confirm the successful synthesis of alendronate-chitosan conjugate.

Abstract: Solid freeform fabrication, known as rapid prototyping (RP) technology allows in designing the scaffold with pre-defined and controlled external and internal architecture.In this study we produce scaffolds with network of chitosan fibrils that mimic the extracellular matrix produced by the cells. These network scaffolds also consisting of nanoparticles of hydroxyapatite (HA) for stabilisation of scaffolds are characterised by environmental scanning electron microscopy and mechanical properties. ESEM showed that the scaffolds possess macropore (300µm), micropore and fibre network structure. The compressive strength and elastic modulus (E) for the scaffolds are 0.54± 0.02 MPa and 6.13± 0.60 MPa, respectively, which are increasing obviously. The biocompatibility of the woodpile-network scaffolds was investigated with osteoblastic cells. The result showed the distribution and proliferation of osteoblast orients along the chtosan fibre network, preferentially. After 4 weeks of culture, macropore channels are covered by cells in large part,while the areas without chitosan fibre network are covered rarely. The properties of these scaffolds indicate that they can be used for bone tissue engineering applications.

Abstract: In this work, Antheraea pernyi silk fibroin (ASF) /chitosan (CS) blend scaffolds were prepared by freeze-drying. The relationship between preparation conditions and morphological structures of blend scaffolds was also studied. The results indicated that the porosity and pore diameter of the ASF /CS scaffolds decreased with increasing of the proportion of chitosan and decreasing of the freezing temperature. By changing the process conditions, the average pore diameter and porosity of ASF/CS scaffolds could be adjusted in the range of 134 - 527 μm and 71 - 91% respectively. Compared with the pure ASF or CS materials, the ASF / CS (60/40) blend materials were more favor of cell adhesion.