Ordered mesoporous silicas for potential applications in solid vaccine formulations

• Published in: Vaccine 2024-01, Vol.42 (3), p.689-700
• Main Authors: Miranda, Matheus C.R., Nunes, Carmen M., Santos, Luana F., da Silva, Leonardo B., de Jesus, Vinicius R., Filho, Newton Andréo, Pedro, Jéssica A.F., Lopes, José L.S., Oliveira, Cristiano L.P., Fantini, Marcia C.A., Cardoso, Jessica S., Trezena, Aryene G., Ribeiro, Orlando G., Sant'Anna, Osvaldo A., Tino-De-Franco, Milene, Martins, Tereza S.
• Format: Article
• Language: English
• Subjects: Adequacy; Antigens; Bovine serum albumin; Circular dichroism; COVID-19 vaccines; Cytokines; Dichroism; Disease transmission; Evaporation; Fluorescence spectroscopy; Freeze drying; Immunogenicity; Immunoglobulin G; Infectious diseases; Pandemics; Pathogens; Pharmaceutical industry; Pore size; Pore size distribution; Preservation; Protein structure; Proteins; Public health; Residues; SBA-15; Secondary structure; Silica; Silicon dioxide; Size distribution; Solid vaccine; Spectra; Surface area; Toxicity; Tryptophan; Vaccine adjuvant; Vaccines; X-ray scattering
• ISSN: 0264-410X; 1873-2518
• DOI: 10.1016/j.vaccine.2023.12.032

•Immunogenic Activity Study: Exploring how solvent removal impacts the immunogenic activity of vaccine antigens in SBA-15.•Effective antigen incorporation: The study shows BSA in SBA-15 enhances immunogenicity, surpassing pure antigen.•Powdered Storage Potential: SBA-15:BSA, a promising solid vaccine. Simplified storage, reduced costs, and ease of use.•Advancing Vaccine Industry: Insights on storage/stability boost vaccine production, advancing global health. In an effort to develop efficient vaccine formulations, the use of ordered mesoporous silica (SBA-15) as an antigen carrier has been investigated. SBA-15 has required properties such as high surface area and pore volume, including narrow pore size distribution to protect antigens inside its matrix. This study aimed to examine the impact of solvent removal methods, specifically freeze-drying and evaporation on the intrinsic properties of an immunogenic complex. The immunogenic complexes, synthesized and incorporated with BSA, were characterized by various physicochemical techniques. Small Angle X-ray Scattering measurements revealed the characteristic reflections associated to pure SBA-15, indicating the preservation of the silica mesostructured following BSA incorporation and the formation of BSA aggregates within the macropore region. Nitrogen Adsorption Isotherm measurements demonstrated a decrease in surface area and pore volume for all samples, indicating that the BSA was incorporated into the SBA-15 matrix. Fluorescence spectroscopy evidenced that the tryptophan residues in BSA inside SBA-15 or in solution displayed similar spectra, showing the preservation of the aromatic residues’ environment. The Circular Dichroism spectra of BSA in both conditions suggest the preservation of its native secondary structure after the encapsulation process. The immunogenic analysis with the detection of anti-BSA IgG did not give any significant difference between the non-dried, freeze-dried or evaporated groups. However, all groups containing BSA and SBA-15 showed results almost three times higher than the groups with pure BSA (control group). These facts indicate that none of the BSA incorporation methods interfered with the immunogenicity of the complex. In particular, the freeze-dried process is regularly used in the pharmaceutical industry, therefore its adequacy to produce immunogenic complexes was proved Furthermore, the results showed that SBA-15 increased the immunogenic activity of BSA.