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In order to develop a non toxic and biocompatible hydrogel system with potential ability in biotechnology, modified photo-crosslinkable hydrogel membranes based on chitosan were prepared. Using an EDC/NHS conjugation method, chitosan was chemically modified to incorporate a photosensitive α-cyano-4-hydroxycinnamic acid moiety with various degrees of substitutions. Fourier transform infrared spectra...
A novel injectable in situ cross-linked hydrogel has been designed via Michael type addition between thiol-modified chitosan (CS–NAC) and PEG diacrylate (PEGDA). Hydrogel was rapidly formed in situ under physiological conditions. The gelation time depended on the content of free thiols in CS–NAC, temperature, and concentration of CS–NAC and PEGDA. Thermogravimetric analysis showed the thermal stabilities...
H 3 PW 12 O 40 (12-phosphotungstic acid; PWA) is efficient catalysts for the selective oxidation of alkanes, aldehydes, and perfluorinated acids. However, PWA molecules are high solubility in water and this property has been making it difficult to utilize as an industrial catalyst. In this study, the water-insoluble PWA-conjugated chitosan matrix was prepared by mixing the...
Graft copolymers of chitosan with acrylonitrile (AN) were prepared by free radical polymerization using initiator pair of ammonium persulfate and sodium thiosulfate as redox system firstly. Graft copolymerization was confirmed by FTIR spectra, X-ray diffraction and 1 H NMR spectra measurements. The mechanism of graft copolymerization and factors affected graft reaction were explored in details,...
A series of chemical modifications of chitosan were conducted by grafting a hydrophilic methoxy poly(ethylene glycol) (MPEG) and a target sugar molecule lactobionic acid (LA). The MPEG was grafted onto C6–OH position of chitosan, and the grafting degree was reduced for chitosan with high degree of depolymerization. The lactobionic acid was proposed to graft onto C2–NH 2 position of chitosan...
Chitosan containing nanofibrous filter media has the advantage of filtering material based on both its size and functionality. They can be potentially applicable in a wide variety of filtration applications ranging from water purification media to air filter media. We have fabricated nanofibrous filter media by electrospinning of chitosan/PEO blend solutions onto a spunbonded non-woven polypropylene...
Polycaprolactone (PCL) and chitosan (CHT) are immiscible polymers. However, biodegradable porous scaffolds of both polymers were obtained by combining different techniques based on the synthesis of semi-interpenetrating polymer networks (SemiIPNs) and melt processing. SemiIPNs were prepared through simultaneous precipitation of the polymer blend (PCL/CHT) and subsequent crosslinking of chitosan with...
Chitosan grafted with hydrophobic and hydrophilic groups initiates the formation of amphiphilic chitosan nanospheres. The molecular weight of mPEG plays an important role to control the particle size. As compared to mPEG 2000, which gives a bimodal nanosphere (∼200, and ∼300nm), mPEG 5000 initiates a monodispersed nanosphere with the smaller size (150nm). In aqueous solution, the nanosphere surface...
Nanofibers were fabricated by electrospinning a mixture of cationic chitosan and neutral poly(ethylene oxide) (PEO) at a ratio of 3:1 in aqueous acetic acid. Chitosan ((1→4)-2-amino-2-deoxy-β-d-glucan) is a multifunctional biodegradable polycationic biopolymer that has uses in a variety of different industrial applications. Processing conditions were adjusted to a flow rate of 0.02ml/min, an applied...
Poly(N-isopropylacrylamide) end-capped with a carboxyl group (PNIPAM-COOH) was grafted to chitosan for synthesizing thermo-reversible chitosan-g-poly(N-isopropylacrylamide) (CPN), which was further grafted with hyaluronic acid (HA) to form hyaluronic acid-g-CPN (HA–CPN). PNIPAM-COOH, CPN and HA–CPN formed injectable free-flowing aqueous solutions and exhibited reversible sol-to-gel phase transition...
We report the formation of non-woven fibers without bead defects by electrospinning blend solutions of chitosan and polyacrylamide (PAAm) with blend ratios varying from 75wt% to 90wt% chitosan using a modified electrospinning unit wherein polymer solutions can be spun at temperatures greater than ambient up to 100°C. Electrospinning at elevated temperature leads to further expansion of the processing...
Poly(ethylene glycol)–polydimethylsiloxane (PEG–PDMS) block copolymers were prepared via a condensation reaction between PEG diacid and PDMS diol. PEG diacid was synthesized from the reaction between hydroxy-terminated PEG and succinic anhydride. PDMS diol was prepared from the ring-opening polymerization of octamethylcyclotetrasiloxane (D 4 ) followed by hydrosilylation with allyl alcohol...
Chitosan/layered silicate nanocomposites with different ratios were successfully prepared via solution-mixing processing technique. Unmodified Ca 2+ -rectorite and organic rectorite modified by cetyltrimethyl ammonium bromide were used. Their structures were characterized by XRD, TEM and FT-IR techniques. The results showed that chitosan chains were inserted into silicate layers to form the...
A novel hybrid material of chitosan–hydroxyapatite (HAp) composite gel is proposed. The introduction of epoxy ring onto chitosan via phthaloylchitosan to obtain a precursor from homogeneous DMF solution is demonstrated. The reaction of the precursor with hydrazine in water gives the recovery of amino groups as well as the ring opening reaction of oxirane for gelation. An alternate soaking with calcium...
We utilized alginate sodium (ALG) and chitosan (CHI) as wall components to construct a natural and biodegradable polyelectrolyte microshell by the electrostatic self-assembly technique. The resultant ALG–CHI shells were found to maintain intact spherical shape in different poly(styrenesulfonate sodium) (PSS) bulk concentrations (maximal detection concentration 20.0wt%). Compared with the shells composed...
‘Caved-in’ and spherical polypyrrole (PPy) capsules were successfully prepared by direct polymerization of pyrrole on polyelectrolyte hollow-capsule microreactors at different conditions. This microreactor was formed by alternate layer-by-layer (LbL) adsorption of chitosan (CS) and poly(sodium 4-styrenesulfonate) (PSS) on polystyrene (PS) colloidal particle and followed by removing the PS core with...
In this study, synthesis and characterization of a new galactosylated chitosan with high affinity to HepG2 (a liver cancer cell line) were reported. We designed the novel glycoconjugated macromolecule using chitosan to be grafted with branched galactose units. The branch-type of galactosylated chitosan was prepared by firstly introducing l-lysine spacer arms to chitosan, followed by covalent coupling...
Novel sunflower-like organic–inorganic composites consisting of spherical silica and smaller conductive polypyrrole particles were successfully prepared through an in situ self-assembly polymerization process by choosing chitosan as a modifying agent of silica surface. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that on the surface of individual silica particle...
The blends of chitosan, polyvinyl alcohol and chitosan polyvinyl pyrrolidone in dilute acetic acid were found to be compatible by viscosity measurements. The dielectric behavior of the investigated blends were studied using frequency response analyzer covering a frequency range from 10 2 to 10 6 Hz and in a wide range of temperature. The permittivity ε′ was found to decrease by increasing...
Electrorheological (ER) response of biocompatible particles suspended in an insulating silicone oil, was investigated under several different applied external electric field strengths. Chitosan, a biodegradable polysaccharide, was used as anhydrous ER materials. The effect of particle volume concentration on their ER response was examined by focusing on the measurement for rheological and electrical...
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