Chitosan-Based Particulate Systems for Non-Invasive Vaccine Delivery

The use of particulate systems is considered very promising for the delivery of antigenic molecules via parenteral and non-parenteral routes. They provide improved protection and facilitated transport of the antigen as well as more effective antigen recognition by the immune cells, which results in enhanced immune responses. The natural cationic polysaccharide chitosan has been investigated extensively both as an adjuvant and delivery system for vaccines. It has been shown to enhance both humoral and cellular responses. From the formulation point of view, chitosan-based particulate systems offer advantages over the other polymers used by avoiding the harsh conditions of heat and/or organic solvents for encapsulation of the antigen. Furthermore, versatility in the physicochemical properties of chitosan provides an exceptional opportunity to engineer antigen-specific adjuvant/delivery systems. In this review, the importance of chitosan in particulate systems for vaccine delivery will be emphasized according to administration routes, particularly focusing on non-invasive (needle-free) routes including oral, mucosal and pulmonary mucosae as well as skin.