Progress in chitosan-based vaccine delivery systems

The biopolymer chitosan, derived from chitin by deacetylation, has been considered for drug and vaccine carrier systems due to its biocom- patibility, biodegradability, and absence of toxicity. In addition, chitosan serves as the base for the synthesis of various derivatives, having, for example, increased aqueous solubility at a wide pH range or offering the opportunity for functionalization with targeting moieties. As the polymer was described as displaying adjuvant properties also, chitosan and its derivatives are used in vaccine delivery systems, alone or in combination with other polymers. This review highlights the current status of the use of chitosan and its derivatives in vaccine carrier design.