Novel approach to improve vaccine immunogenicity: Mannosylated chitosan nanoparticles loaded with recombinant hepatitis B antigen as a targeted vaccine delivery system

The design of effective vaccine delivery system is opening up new feasibilities for making immunization more safe and efficient. In this study, recombinant hepatitis B virus surface antigen (rHBsAg) was loaded in mannosylated chitosan (MC) nanoparticles to be used as a targeted vaccine delivery vehicles. The nanoparticles were prepared by ionic gelation method and characterized for physicochemical properties, cytotoxicity and antigenicity. The rHBsAg-loaded MC nanoparticles showed spherical shape with mean particle size of 246 +/- 33 nm, zeta potential of 25.6 +/- 1.7 mV, loading capacity of 12.2 +/- 1.4%, and encapsulation efficiency of 90 +/- 1.6%. In vitro release profile of rHBsAg-loaded MC nanoparticles exhibited an initial burst release of about 26% in the first 7 days followed by a slow release of 25% for 49 days, with release kinetic similar to Higuchi model. SDS-PAGE analysis confirmed integrity of released rHBsAg and structural stability of the antigen during entrapment process. The rHBsAg-loaded MC nanoparticles indicated time-and concentration-dependent cytotoxicity using MTT assay. It can be concluded that entrapment of rHBsAg in MC nanoparticles appears to be a suitable approach for targeting this antigen into body immune system.