Carboxymethyl Chitosan for Drug and Vaccine Delivery: An Overview

Chitosan is a biopolymer derived from natural chitin, which is the principal component of the exoskeletons of crustaceans and insects as well as of the cell walls of some bacteria and fungi. Like cellulose, it is a glucose-based unbranched polysaccharide. Chitosan has been widely employed in various biomedical areas for both therapeutic purposes and delivery of the drugs and vaccines. Yet, the poor water solubility of chitosan limits its application areas and applicable fields. The modification of chitosan has been an important approach to address this issue, which involves, most commonly, the utilization of the free amino and hydroxyl groups of chitosan as reactive functional sites to generate a wide range of chitosan derivatives with improved solubility. The derivatives of chitosan keep the original physicochemical properties of chitosan such as bioadhesivity, biodegradability, and penetration enhancement as well as the bioactive properties such as antimicrobial, wound healing, anti-inflammatory, immunostimulatory, tissue regeneration, etc., while exerting new and/or improved characteristics depending on the nature of additional functions. Due to its chemical characteristics and the technical feasibility of its synthesis and utilization, carboxymethyl chitosan has been widely investigated for drug and vaccine delivery in different forms such as hydrogels, fibers, films, nanoparticulate systems, etc., as well as for its bioactive properties. In this chapter, an overview of chitosan derivatives used for drug and vaccine delivery will be provided, with a special emphasis on carboxymethyl chitosan and its applications in the pharmaceutics field.