Preparation Of Chitosan Derivatives And Their Properties On The Controlled Release And Bioactivity

Smart hydrogels can response to the change of environment, as a kind of intelligent materials, which will be applied in many fields. On the other hand, chitosan, a naturally abundant polymer, has a wide range of application, especially in bioactivity. There are two parts in review. One focus on properties, preparation and applications of smart hydrogels. Another is properties and bioactivity of chitosan including the effect of molecular size on its properties.pH sensitive hydrogels based on chitosan (chitosan-polyvinyl pyrrolidone, chitosan-polyvinyl alcohol, chitosan-polyethylene glycol) were synthesized by using the means of interpenetrating network(IPN). The IPN structure of them were characterized by element analysis, IR spectra, SEM and DTA. The hydrogels showed excellent pH sensitivity, which can swell in acid medium and contractile in base medium. Furthermore, the hydrogels have good swelling-contracting reversibility in the solution which pH value was alternately changed, and can be used as delivery system of norfloxacin.Nano-chitosan were prepared from oxidation degrade with hydrogen peroxide and characterized by element analysis, IR spectra, GPC, TEM and AFM. Nano-chitosan and glycine metal complexes(CS-M-Gly, M: Zn, Ni, Cu, Co, Fe) were prepared from nano-chitosan, and characterized by element analysis, IR spectra, ICP and XPS.The interaction between CS-M-Gly with DNA was investigated by UV/Vis and fluorescent probe technique. The results showed that CS-M-Gly can destroy the structure of DNA. The antitumor activity of CS-M-Gly were also studied by SRB. The results indicated that CS-M-Gly can inhibit the growth of liver cancer H7402 cell and the death percent of CS-Cu-Gly to tumor cell is 88.46%.Nano-chitosan salicylaldehyde Schiff base and glycine metal complexes (CS-Sal-M-Gly, M: Zn, Ni, Cu, Co, Fe) were synthesized, and characterized by element analysis, IR spectra, ICP and XPS. The bioactivity of CS-Sal-M-Gly were investigated by UV/Vis, fluorescent probe and SRB, the results showed thatCS-Sal-M-Gly can make interaction with DNA and destroy its structure. Moreover, CS-Sal-M-Gly have better antitumor activity. The death percent of tumor cell can reach 90.28% in the presence of CS-Sal-M-Gly. That means the cell toxicity of CS-Sal-M-Gly to tumor cell is the highest four grade.