The aim of the present investigation was to evaluate the prospective of surface-engineered vesicular carriers for mucosal immunization via the nasal route. IgG antibody was immobilized on the surface of hepatitis B surface antigen (HBsAg) antigen–loaded liposomes. The developed formulations were characterized on the basis of physicochemical parameters, such as morphology, particle size, polydispersity index, entrapment efficiency, and zeta potential. Liposomal formulations were then evaluated for in-process antigen stability and storage stability. In vivo studies were conducted to visualize targeting potential, localization pattern, and immunogenicity. In addition, immune response was compared with alum-HBsAg vaccine injected intramuscularly. The serum anti-HBsAg titer, obtained from the postnasal administration of IgG-coupled liposomes, was significantly higher than plain liposomes. Moreover, IgGcoupled liposomes generated both humoral (i.e., systemic and mucosal) and cellular immune responses upon nasal administration, while the alum-adsorbed antigen displayed neither cellular (cytokine level) nor mucosal (IgA) response. The formulation also displayed enhanced transmucosal transport, improved in vitro stability, and effective immunoadjuvant property. To conclude, IgG antibody-coupled liposomes may serve as novel carriers to augment the secretory immune response of antigen encapsulated in the liposomes, apparently by escalating liposome uptake via M cells, thereby rationalizing their use as a carrier adjuvant for nasal subunit vaccines.
