N-Carboxyacyl chitosan and their characterizations for potential use in medical applications

Abstract

y N-maleoyl chitosan and N-succinyl chitosan which are both water soluble chitosan derivatives, were successfully synthesized by the introduction of maleic anhydride and succinic anhydride into the amino group of chitosan, respectively. The self-crosslinkable N-maleoyl chitosan films were indicated by the reduction of their swelling and weight loss behaviours toward the storage time of films. Moreover, the swelling behaviour of this chitosan derivative was also sensitive to the changes of pH and ionic strength of the solutions. For N-succinyl chitosan, hydrogel of this chitosan derivative was fabricated by direct crosslinking of chitosan with succinic anhydride via the chitosan-citric acid complexation. It was found that the increase of succinylation of the hydrogel resulted in an enhancement of succinyl linkage, cationic dye absorbability, susceptibility to the lysozyme degradation. Moreover, the nontoxicity of these N-succinyl chitosan hydrogel films toward the mouse fibroblast cells was confirmed by indirect cytotoxicity evaluation. After exposure to low dose (5-30kGy) of gamma radiation, the reduction of molecular weight of N-succinyl chitosan products in their dilute aqueous solution system was greater than in their solid film state. The structural analysis suggested that the radiolysis of N-succinyl chitosan products was mainly occurred at the glycosidic linkages and N-succinyl groups were partially eliminated. As results of their physicochemical properties, biodegradability and cytotoxicity, both fabricated N-maleoyl chitosan and N-succinyl chitosan have a potential use for applying in medical applications. In addition, low molecular weight of N-succinyl chitosan can be effectively produced by using gamma radiation at dilute aqueous solutions.