5 - Chitosan-based polyelectrolyte complexes in biomedical applications

Abstract

Chitosan and its derivatives have been widely explored as polymeric drug carriers in biomedical research due to their biocompatibility, biodegradability, nontoxicity, and low-cost production from renewable resources. At low pH values (i.e., below its pKa of 6.5), the primary amines of chitosan remain positively charged and can spontaneously interact with polyanions to form a polyelectrolyte complex (PEC). The fabrication process of PECs is simple and performed under mild conditions without using any chemical cross-linker, surfactants, or organic solvents. Therefore the chitosan-based PECs are well-tolerated and ideal carriers for the delivery of susceptible drugs and macromolecules. In this chapter, an overview of chitosan, including its general structure, sources, and physicochemical properties, is presented. This chapter also discusses the mechanism of PECs formation, general preparation procedure, and various extrinsic and intrinsic factors affecting the formation and stability of PECs. Finally, the recent developments in chitosan-based PECs and their applications in drug delivery, gene delivery, and tissue engineering are discussed in detail.