Chitosan-based Particulate System for Oral Vaccine Delivery: a Review

Mucosal vaccination is a promising alternative to classical parental vaccination, as it is non-invasive and, in principle, capable of eliciting strong systemic and local immune responses. Chitosan has already gained considerable attentions as vehicles for protein drug delivery due to its excellent biocompatibility, biodegradability and non-toxicity. However, its poor aqueous solubility and loss of penetration-enhancing above pH 6 are major drawbacks for its use as oral vaccine carrier. In recent years, the area of focus has shifted from chitosan to chitosan derivatized polymers for the preparation of nanoparticles due to their vastly improved properties, such as acid resistivity, better drug retention capability, improved permeation, enhanced mucoadhesion and sustained release of therapeutic antigens. Additionally, interaction with counter ions such as sulfates or polyphosphates facilitates its usefulness in the coating or entrapment of antigenic molecules as a vaccine candidate. The current review focuses on the recent advancements in the field of oral vaccine delivery via chitosan-based particulates, describes the various methods used to design and synthesis and discusses about their in vitro and in vivo implications.