ABSTRACT
Chitosan is a natural polysaccharide possessing biocompatible and biodegradable (Muzzarelli 1997, Muzzarelli and Muzzarelli 2002) properties. It has received great attention from researchers due to its wide application in medical and pharmaceutical elds. Its favorable intrinsic properties and highly abundant natural resources make it a versatile utility material for various medical applications such as topical ocular application (Felt et al. 1999), implantation (Patashnk et al. 1997) or injection (Song et al. 2001). Owing to its positive charges at physiological pH, chitosan could bind itself to the negatively charged surfaces of most of the cells and living tissues and thus also used as bioadhesive, which increases retention of the therapeutic material at the site of application (Calvo et al. 1997, He et al. 1998). Chitosan is used as a component in hydrogels and has been exploited in various medical and pharmaceutical applications especially in sustained release of anticancer drugs, delivery of sensitive biological materials such as proteins and living cells, and release of macromolecules over a period of several hours to a few days in a controlled manner.
