Chapter 15 - Chitosan for gene, DNA vaccines, and drug delivery

Abstract

Cationic polymers such as chitosan have been shown to be potential vectors for gene and drug delivery. Chitosan is a natural polymer obtained by alkaline deacetylation of chitin. Chitosan and its derivatives have been extensively explored in several biomedical applications due to their biodegradability, biocompatibility, low cytotoxicity, low immunogenicity, transcellular transport ability, favorable physicochemical properties, and ease of chemical modifications. Chitosan backbone contains many reactive primary amine groups in its repetitive units, which are accountable for certain properties including transfection, permeation enhancement, mucoadhesion, chemical modifications, and the formation of a variety of favorable derivatives, making it an attractive tool for gene, DNA vaccines and drug delivery. Chitosan can form complexes with negatively charged DNA and proteins through ionic interactions, condensing DNA into small particles (nanoparticles), protecting it from DNase degradation, and enhancing protein stability. Moreover, modifications in the chitosan chain using hydrophilic and hydrophobic moieties improve its solubility, enhance the transfection efficiency, and increase ability to release DNA after endosomal escape. The coupling of target-specific ligands to chitosan can improve receptor specific targeting of delivery systems which results in an increase its efficacy. Therefore chitosan nanocomplexes are versatile systems that can be explored for gene, DNA vaccines and drug delivery.