L.C. Cides da Silva

Physical properties of ordered mesoporous SBA-15 silica as immunological adjuvant*

This work reports a detailed analysis of the ordered mesoporous SBA-15 silica synthesis procedure that provides a matrix with mean pore diameter around 10 nm. The encapsulation of bovine serum albumin (BSA) by four different methods allowed the determination of the best imbibition condition, which is keeping the mixture under rest and solvent evaporation. Simulation of the in situ SAXS scattered intensity of the BSA release in potassium buffer solution, gastrointestinal fluids revealed a slow evolution of BSA content, independent of the media. Proton induced x-ray emission results obtained in calcined mouse organs revealed that silica is only present in the spleen after 35 days and is completely eliminated from all mouse organs after 10 weeks. Biological studies showed that Santa Barbara Amorphous-15 is an effective adjuvant when compared to the traditional Al(OH)3, and is non-toxic to mice, rats, dogs and even cells, such as macrophages and dendritic cells. Recent studies showed that the immunological response is improved by enhancing the inflammatory response and the recruitment of immune competent cells to the site of injection as by the oral route and, most importantly, by increasing the number of phagocytes of a particulate antigen by antigen presenting cells.

Microwave synthesis of FDU-1 silica with incorporated humic acid and its application for adsorption of Cd2+ from aqueous solutions

This work describes microwave synthesis of FDU-1 materials with and without humic acid. FDU-1 is cage-like ordered mesoporous silica with a face-centered cubic structure. The FDU-1 samples were prepared using poly(ethylene oxide)-poly-(butylene oxide)-poly(ethylene oxide) triblock copolymer (EO39BO47EO39) as template and tetraethyl orthosilicate (TEOS) as silica source. The samples with incorporated humic acid were synthesized by using different concentrations of humic acid, i.e., 1.0, 1.5 and 2 mmoles. The resulting materials were characterized by thermogravimetry, elemental analysis, nitrogen adsorption, and small angle X-ray diffraction. The samples with incorporated humic acid were tested for removal of Cd2+ from aqueous solutions at pH=6. It is shown that the incorporation of humic acid into FDU-1 afforded materials with high adsorption capacity for cadmium ions. These materials seem to be promising adsorbents for removal of cadmium and related heavy metal ions from aqueous solutions.