Development and characterization of HBsAg-loaded Eudragit nanoparticles for effective colonic immunization

The present study was undertaken with an aim to investigate the potential of targeting colonic mucosa following oral vaccine delivery to generate prophylactic humoral and mucosal immune response. In present study, response surface methodology (RSM) using the central composite design (CCD) was applied for optimization of process and composition to get uniform, stable reproducible eudragit nanoparticles suitable for targeting to colon. The optimized formulation had the composition of 173 μg HBsAg, 250 mg polymers concentration (4:1 combination of Eudragit S-100 and L-100) and 2% w/v Polyvinyl alcohol (PVA) along with adjuvant Monophosphoryl lipid A (MPLA). Mean particle size of optimized nanoparticles was found to be 730.4 nm, entrapment efficiency (58.38%) and polydispersity index of 0.185. Fluorescent spectroscopy, differential scanning calorimetry, and antigen integrity by SDS-PAGE established that antigen structure was preserved during and after formulation development. In-vitro release studies in different intestinal pH concluded antigen release at mild alkaline conditions. Real time fluorescence animal imaging confirmed the effective absorption and distribution of NPs at colon resulted in improved immune response. Present study concludes that Eudragit nanoparticles offers strong potential in colon targeting of vaccines through oral immunization.