Abstract:
Nanoparticles formulated from biodegradable polymers are being extensively investigated as non-viral gene delivery system due to their controlled release characteristics and biocompatibility. The objective of the present work was to evaluate the potential of pDNA loaded chitosan biodegradable nanoparticles as an oral vaccine delivery system against rotavirus. Chitosan nanoparticles were prepared by gelation method in presence of cross-linking agents namely gluteraldehyde and TPP. The influence of formulation parameters including the type of cross-linking agent, its concentration and the molecular weight of the polymer on physical properties and adsorption characteristics of chitosan nanoparticles were studied. Both gluteraldehyde and TPP have increased the surface hydrophobicity of the nanoparticles, however, the surface hydrophobicity of gluteraldehyde cross-linked nanoparticles was significantly greater than TPP cross-linked nanoparticles. Moreover, the surface hydrophobicity increased as the concentration of cross-linking agent increased in the formulation. The adsorption efficiency of pDNA onto the surface of chitosan nanoparticles was found to be affected by the formulation parameters investigated. Gluteraldehyde resulted in reduction in the adsorption efficiency of the nanoparticles in comparison with non-crosslinked particles whereas, TPP cross-linker has slightly increased the amount of pDNA adsorbed. Nanoparticles prepared using low and high molecular weight polymers exhibited adsorption efficiency higher than 95% whereas nanoparticles produced from medium molecular weight polymer exhibited adsorption efficiency approximately 88%. SEM revealed that the nanoparticles prepared using different formulation parameters were spherical and exhibited a particle size less than 1 µm. In vivo studies on infant mice showed that groups given DNA loaded nanoparticles and naked DNA developed higher antibody titres in comparison with the control group. Moreover, mice treated with DNA loaded nanoparticles vaccine developed higher IgM and IgA titres than those treated with naked DNA vaccine. Whereas, IgG titre was higher in the naked DNA group but the difference was not statistically significant. The results of this study showed that chitosan nanoparticles hold promise as an oral delivery system for DNA rotavirus vaccine however further studies and testing are required.