The carboxymethylated chitosan (CMCts) hydrogels were synthesized by c-ray radiation-induced crosslinking at paste-like state with the concentration of CMCts from 12% to 22%. The gel fraction firstly increased with adsorbed dose and leveled off at ca. 20 kGy. The diffusion behavior of water in CMCts gels was Fickian diffusion, and the swelling of CMCts gels was affected by pH and ionic strength. Preliminary crosslinking mechanism of CMCts with c-ray irradiation was discussed based on the FTIR and sol-gel analysis. The adsorption kinetics study showed that the adsorption of Fe(Ⅲ) ions onto CMCts gels was very fast (ca. 20 min) due to the coordination of Fe(Ⅲ) ions with amino, hydroxyl and carboxyl groups of CMCts molecules. pH 4.7 was the optimum for the adsorption of Fe(Ⅲ) ions onto CMCts gels. The maximum uptake of Fe(Ⅲ) ions, based on Langmuir equation, was determined to be 18.5 mg/g gel.

A facile ultraviolet (UV) light irradiation method to synthesize gold nanoparticles (AuNPs) in the alkalic carboxymethylated chitosan (CMchitosan) solution was first proposed in this paper. CM-chitosan, a water soluble polysaccharide derivative, served as both reducing agent for gold cations and stabilizing agent for AuNPs. The pH, the concentration of HAuCl4 and irradiation time had obvious influence on the size, amount and morphology of AuNPs, which traced by UV–visible spectrometer and high resolution transmission electron microscopy. AuNPs synthesized in this method can be dispersed stably in alkalic CM-chitosan solution for more than 6 months. The possible stability mechanism of AuNPs was discussed based on the change of carboxyl group of CM-chitosan chain with pH and FTIR analyses. XRD pattern confirmed the cubic crystal structure of AuNPs. The fluorescence emission band of AuNPs with an excitation wavelength of 316 nm can be observed at 400 nm, which was affected remarkably by irradiation time and concentration of HAuCl4.

Natural oligosaccharide-derived room temperature ionic liquids (RTILs) were prepared from 1-ethyl-3-methylimidazolium hydroxide (EMIMÆOH) and carboxymethylated chitosan (CM-chitosan) by acid–base neutralization reaction. These EMIMÆCM-chitosan ionic liquids exhibited good ionic conductivity and thermal stability, as well as low glass transition temperature, implying their potential wide applications in direct electrochemistry, biosensors, and biocatalysis.

In order to develop a nontoxicity, biocompatibility, pH-sensitive hydrogel system with potential ability to immobilize and absorb proteins, the hydrogel membranes of poly(N-vinylpyrrolidone) (PVP) and carboxymethylated chitosan (CM-chitosan) blend were prepared with electron beam (EB) irradiation at room temperature. The FTIR spectroscopic, mechanical property, swelling behavior, and surface property of the hydrogel membrane were measured. The capacity of these gel membranes to adsorb bovine serum albumin (BSA) was investigated with varying content of CM-chitosan by static adsorption experiment at pH 7.4. The mechanical and swelling properties were improved obviously after adding CMchitosan into PVP hydrogels. The changes of contact angles of water, glycerin and octane drops on the blend membranes surface with increasing CM-chitosan content indicated that the CM-chitosan molecules were more hydrophilic than PVP molecules, and cause a larger polar component of surface free energy. The incorporation of CM-chitosan introduced the protein adsorptive property into blend system. From these preliminary evaluations, it is possible to conclude that these materials have potential for applications in the biomedical field.