Carbonate apatite nanoparticles: A novel nano-adjuvant for oral mucosal vaccines and immunomodulator

Vaccines manufacture and enhancement for preventing infection and promoting quality of life are
of great concern worldwide. For vaccine enhancement, to date, only limited adjuvants have been
approved globally. One of them is alum, which presents several side effects and limitations.
Related to vaccine administration, mucosal vaccination is a promising method since it can induce
both mucosal and systemic immunity since oral mucosa is the most exposed site of the body to
various microbes, pathogens, and environmental particles. Consequently, an escalated specific
local immunity is required in which stability and integrity of an encapsulated antigen is expected
to result in a stable mucosal vaccine to protect the antigens from degradative chemical reactions
occurring in the oral cavity and act as immunomodulator. Carbonate apatite (CHA) has been one
of the most innovative materials as a newly developed vaccine adjuvant since it can adequately
enhance drug and protein stability and delivery in various disease therapies. However, CHA
fabrication that meets the parameters for adjuvants and immunomodulators remains challenging.
In the form of nanoparticles, CHA is reported to enable targeted delivery of dendritic cells (DC),
enhance uptakes, cross presentation, and biodistribution, as well as immune responses. Therefore,
the development of nano-CHA-encapsulated vaccine antigens is required to enhance oral mucosal
vaccinations and their effectiveness to prevent diseases. This study focuses on factors and strategies
that affect the designing, fabrication, and testing of CHA nanoparticles for oral mucosal
vaccines, especially in the aspect of physicochemical, immunological, cellular, surface chemistry,
and biofunctionalization of the nanoparticle.