Chitosan as natural polysaccharide chitin removal of acetyl products

because of their excellent physical and chemical properties and biological activities

become one of the most promising polymer in biomedical applications

as a result of chitosan in poor solubility in neutral and alkaline solution

its application is limited by a certain

Usually

chitosan is functionalized and modified to generate a series of chitosan derivatives. Chitosan derivatives can improve the water solubility

biological activity and mechanical properties of chitosan

so as to enhance its utilization value and expand its application field. Several functionalization methods of chitosan

including graft copolymerization

crosslinking

carboxymethylation

acylation and alkylation

were reviewed in this paper. The research progress of the application of modified chitosan as drug carrier was introduced in order to provide some theoretical basis for the study of modified chitosan.