Development and Characterization of O-methylated Free N, N, N- Trimethylated Chitosan Nanoparticles as New Carriers for Oral Vaccine Delivery in Mice

Chitosan (CS) has already gained considerable attentions as vehicles for mucosal immunizations due to its excellent biocompatibility, biodegradability and non-toxicity. However, poor aqueous solubility and loss of penetration-enhancing above pH 6 are major drawbacks for its use as oral vaccine carrier. The study aims to investigate the potential utility of O-methylated free trimethylated chitosan (CS-TM) nanoparticles as an effective adjuvant for oral vaccine delivery. Nanoparticles were formulated by modified coacervation method using different MW of CS consisting two different degree of quaternization (DQ) to which measles antigen was entrapped by an ionic cross-linking technique. Drug loading, encapsulation efficiency, and particle properties such as SEM, size distribution and zeta potential were evaluated. In vitro release studies showed an initial burst followed by extended release of antigen from all formulations, best fitted the Higuchi model. SDS-PAGE assay showed that CS-TM nanoparticles could effectively protect the antigen from degradation in acidic condition for at least 2 h. Cell viability was assessed using MTT assay into HT29 cell line. CS-TM nanoparticles of different formulations were orally administered to mice and immunological responses were evaluated using dried blood spot ELISA method. Obtained results showed that antigen-loaded CS nanoparticles induced strong humoral immune response and significant correlation was observed between the immune response with DQ. Protecting ability of antigen in the gastric environment, sustained release kinetics, enhancement of the systemic and mucosal immune responses and low cytotoxicity observed for the CS-TM nanoparticles demonstrated that it could be a promising platform for oral vaccine delivery.