Study On The Modification Of Chitosan And Its Intelligent Hydrogel

Chitosan is obtained by alkaline deacetylation of chitin from the shell of shrimp, crab and insects etc, is an alkaline polymer, one of the abundant and reproducible natural polymers in the world. Due to the biocompatibility, biodegradable, no toxicity and environmental friendship, chitosan and its ramifications are potentially be widely applied especially in biomedical applications such as in drug delivery system and artificial soft tissues and so on. Chitosan contains hydroxyl and ammoniac in its unit structure and a special kind of polar polymer could be obtained by the introduction of carbonyl group. Three kind techniques were used for introducing carbonyl group and three kind hydrogels with special pH sensitive were obtained in this paper.⁶⁰Co γ-ray and electron beam was applied as irradiation source and the pH sensitive chitosan (CS)/poly acrylic acid (PAAc) was obtained by irradiating the solution mixture of chitosan (CS) and acrylic acid (AAc). The CS/PAAc hydrogel obtained in this experimental swelled in the conditions of pH<4 and pH>6, but de-swelled during the pH range of 4-5, which indicated that hydrogel is sensitive in both basic and acidic solution. The magnetic hydrogel microsphere (ferrogel) was synthesized by reversed emulsion polymerization. An anticancer drug, Bleomycin A5 Hydrochloride (BLM) is immobilized into the ferrogel by swollen adsorption and the experiments in vitro and in vivo were performed. The experiment result in vivo indicated that the ferrogel could be easily droved into the targeted area near the tumor by outside magnetic field. The function of embolism and slow release of drug were approved in vivo. An obvious effect of the BLM immobilized ferrogel was observed on the healing of explanted tumor.Carboxyl methyl chitosan (CMCS)/poly-N-isopropylacrylamide (PNIPAAm) hydrogel was prepared by irradiating the aqueous solution mixture of Carboxyl methyl chitosan (CMCS) and N-isopropylacrylamide (NIPAAm) with ⁶⁰Co γ-ray. The swelling behavior was determined in the media of deionized water, different ionic strength solutions and different pH buffer solutions at different temperature, respectively. The results indicated that the low critical solution temperature (LCST) of the CMCS/PNIPAAm hydrogel could be increased above the 37℃ with the content of CMCS. On the other hand, the swelling ratio also much increased compared the homopolymer hydrogel of PNIPAAm. The drug delivery behavior of the CMCS/PNIPAAm hydrogel was studied by using Commas bright blue as the drug...