Hepatitis B surface antigen nanoparticles coated with chitosan and trimethyl chitosan: Impact of formulation on physicochemical and immunological characteristics

► Hepatitis B surface antigen-containing chitosan and TMC nanoparticles were prepared. ► At several pHs/tonicities these particles have comparable physical properties. ► The nanoparticles, administered in hypotonic medium, are potent nasal adjuvants. ► At higher tonicities immunogenicity is maintained for chitosan nanoparticles only. ► Nanoparticles, administered i.m., are more immunogenic than alum adsorbed antigen.