Mesoporous Silica-Supported TiO2 Composite Sunscreen: Combining Low Whitening, Reduced Photoactivity, and Favorable Cytocompatibility

Titanium dioxide, a traditional physical sunscreen agent, has long faced persistent challenges related to light transmission (manifesting as whitening and an unnatural white cast on the skin), high photocatalytic activity, and cytocompatibility concerns. In this work, a composite sunscreen material, mesoporous silica (MSN)@TiO2, was designed and synthesized by loading titanium dioxide (TiO2) onto dendritic mesoporous silica. Leveraging the high transparency of dendritic mesoporous silica, MSN@TiO2 exhibits 30% higher visible light transmittance than commercially available titanium dioxide. In addition, encapsulation within the silica carrier reduces the photocatalytic activity of MSN@TiO2 to one-seventh of that of commercially available titanium dioxide. Furthermore, we evaluated the cytocompatibility of MSN@TiO2. Cell Counting Kit-8 (CCK-8) assay results demonstrate that MSN@TiO2 has a less pronounced effect on L929 cells proliferation compared with commercial TiO2, indicating favorable L929 cell-based cytocompatibility. This strategy demonstrates that MSN@TiO2 combines a natural appearance with low photocatalytic activity, offering distinct advantages over conventional titanium dioxide in composite sunscreen materials.