Induction of protein specific antibody by carbonated hydroxy apatite as a candidate for mucosal vaccine adjuvant

Buccal mucosae are considered as a site for vaccine delivery since they are relatively abundant with antigen-presenting dendritic cells, mainly Langerhans cells. In this study, we formulated carbonated hydroxy apatite (CHA) with ovalbumin (OVA) (denoted as CHA-OVA), incorporated it into bilayer buccal membrane to form hydrogel films containing CHA-OVA complex for vaccination via buccal mucosae. Ethylcellulose blend with polyethylene glycol 400 were used as impermeable backing layer. Physical properties of all tested buccal membranes were found suitable for mucosal application. In vitro and ex vivo release study showed there was no burst release of OVA found from all tested formula. From the in vivo examination, rabbit buccal mucosae vaccinated by mucoadhesive membranes containing CHA-OVA complex demonstrated mucosal specific antibody induction, represented the potential of CHA as a candidate of needle-free vaccine adjuvant. Future research is awaiting to investigate proper CHA crystallinity in complex with protein against targeted diseases.