Miranda Matheus C R, Nunes Carmen M, Losito Danilo W, Rocha Fernanda M, Pedro Jéssica A F, Favoretto Bruna C, Teobaldo Gabriel B M, Cides da Silva LuÍs Carlos, Lopes Jose L S, Oliveira Cristiano L P, Fantini Marcia C A, Ribeiro Orlando G, Sant'anna Osvaldo A, Martins Tereza S
Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Diadema, São Paulo 09913-030, Brazil.
Instituto de Física, Universidade de São Paulo, São Paulo 05508-090, Brazil.
ACS Omega. 2025 Jun 19;10(25):27534-27549. doi: 10.1021/acsomega.5c03459. eCollection 2025 Jul 1.
Ordered mesoporous silica SBA-15 improves the humoral response as a vaccine adjuvant because of its structural properties. Its morphology is dependent on synthesis conditions and can alter antigen encapsulation and immune response; all tested variants were safe and able to immunize against diphtheria. One of the additional advantages of SBA-15 is that its morphology can be modulated by adjusting the synthesis conditions like temperature, stirring speed, and solvent addition. In this study, SBA-15 was selected as a vaccine adjuvant in immunization against diphtheria by varying four modifications of the synthesis parameters for preparing SBA-15 particles with different morphologies. SEM analyses confirmed that different morphologies were obtained including rope-shaped aggregated rods (S1), filiform rods (S2), hexagons (S3), and nanospheres (S4). All synthesized SBA-15 samples presented an ordered mesoporous structure, with the characteristic reflections of a two-dimensional hexagonal structure and lattice parameter values with small differences ((hkl) = ∼11 nm at 12), indicating that the silica mesostructure was preserved after incorporation from diphtheria anatoxin (dANA). The SAXS and NAI results indicate that mainly in samples S1 and S4, the dANA is encapsulated in the mesopores as well as in the SBA-15 macropores. Fluorescence analyses revealed the preservation of the aromatic microenvironment of tryptophan, similar to pure protein, except for sample S3, which showed a shift in emission wavelengths to 356 and 372 nm, indicating exposure of tryptophan to the more polar microenvironment. SRCD analyses confirmed the maintenance of dANA's secondary structure in all samples. In the immunogenic assay, the S3dANA sample stood out, presenting a significantly higher primary immune response. However, the immunogenic responses increased and became equal in the secondary response without any variation between different silica morphologies. It is concluded that all SBA-15-based adjuvants with different morphologies are biocompatible and present a good immunogenic response when they are applied as vaccine adjuvants.
有序介孔二氧化硅SBA - 15由于其结构特性，作为疫苗佐剂可改善体液免疫反应。其形态取决于合成条件，并且会改变抗原包封和免疫反应；所有测试变体均安全且能够针对白喉进行免疫接种。SBA - 15的另一个优点是其形态可通过调整合成条件（如温度、搅拌速度和溶剂添加量）来调节。在本研究中，通过改变合成参数的四种修饰来制备具有不同形态的SBA - 15颗粒，从而选择SBA - 15作为白喉免疫接种的疫苗佐剂。扫描电子显微镜（SEM）分析证实获得了不同的形态，包括绳状聚集棒（S1）、丝状棒（S2）、六边形（S3）和纳米球（S4）。所有合成的SBA - 15样品均呈现有序介孔结构，具有二维六边形结构的特征反射以及晶格参数值存在微小差异（在12时（hkl）= ∼11 nm），这表明从白喉类毒素（dANA）掺入后二氧化硅介观结构得以保留。小角X射线散射（SAXS）和负染（NAI）结果表明，主要在样品S1和S4中，dANA被包裹在介孔以及SBA - 15大孔中。荧光分析显示色氨酸的芳香微环境得以保留，类似于纯蛋白质，但样品S3除外，其发射波长发生了位移，变为356和372 nm，表明色氨酸暴露于极性更强的微环境中。圆二色光谱（SRCD）分析证实在所有样品中dANA的二级结构得以维持。在免疫原性测定中，S3dANA样品表现突出，呈现出显著更高的初次免疫反应。然而，在二次反应中免疫原性反应增加并变得相等，不同二氧化硅形态之间没有任何差异。得出的结论是，所有具有不同形态的基于SBA - 15的佐剂具有生物相容性，并且在用作疫苗佐剂时呈现出良好的免疫原性反应。
