Mesoporous SBA-16 silica nanoparticles as a potential vaccine adjuvant against Paracoccidioides brasiliensis

Nanostructured materials including mesoporous silica nanoparticles (MSNs) have attracted attention due to their recently discovered capability to increase the immune responses acting as an innovative vaccine adjuvant. Therefore, the present work aimed to study the potential use of mesoporous SBA-16 and silanized SBA-16 (APTES-SBA-16) nanoparticles as a vaccine adjuvant against the pathogenic fungus Paracoccidioides brasiliensis (PCM). In this sense, the antigenic protein rPb27 was incorporated into both mesoporous matrices. The synthesized nanomaterials were physicochemical and morphological characterized and the results obtained revealed consistent data with nanosized mesoporous nanoparticles in a monodisperse colloidal system. In the next step, the rPb27 antigen loading efficiency was evaluated using different ratios of nanoparticles/antigen and subsequently, the in vitro release kinetics was evaluated until 63 days. After, rPb27 was successfully radiolabeled with 99mTc and injected into thigh muscle of healthy mice in order to evaluate the in vivo release profile of rPb27 from nanoparticles to the bloodstream. The results revealed that APTES-SBA-16 matrix was capable to maintain a sustained release profile without insignificant cytotoxicity to normal human lineage cells. Altogether, these results suggest that APTES-SBA-16 nanoparticles can considered a potential adjuvant system for developing vaccines against the PCM.