Chitosan non-particulate vaccine delivery systems

Chitosan is an extensively used polymer for drug delivery applications in particulate and non-particulate carriers. Chitosan-based particulate, nano-, and microparticle, carriers have been the most extensively studied for the delivery of therapeutics and vaccines. However, chitosan has also been used in vaccine applications for its adjuvant properties in various hydrogels or as a carrier coating material. The focus of this review will be on the usage of chitosan as a vaccine adjuvant based on its intrinsic immunogenicity; the various forms of chitosan-based non-particulate delivery systems such as thermosensitive hydrogels, microneedles, and conjugates; and the advantages of its role as a coating material for vaccine carriers.