TiO-embedded mesoporous silica with lower porosity is beneficial to adsorb the pollutants and retard UV filter absorption: A possible application for outdoor skin protection.

The purpose of the current investigation was to develop multifunctional TiO-embedded mesoporous silica incorporating avobenzone to protect against environmental stress through pollutant adsorption and UVA protection. We sought to explore the effect of the mesoporous porosity on the capability of contaminant capture and the suppression of avobenzone skin penetration. The porosity of the mesoporous silica was tuned by adjusting the ratio of template triblock copolymers (Pluronic P123 and F68). The Pluronic P123:F68 ratios of 3:1, 2:2, and 1:3 produced mesoporous silica with pore volumes of 0.66 (TiO/SBA-L), 0.47 (TiO/SBA-M), and 0.25 (TiO/SBA-S) cm/g, respectively. X-ray scattering and electron microscopy confirmed the SBA-15 structure of the as-prepared material had a size of 3-5 μm. The maximum adsorbability of fluoranthene and methylene blue was found to be 43% and 53% for the TiO/SBA-S under UVA light, respectively. The avobenzone loaded into the mesoporous silica demonstrated the synergistic effect of in vitro UVA protection, reaching an UVA/UVB absorbance ratio of near 1.5 (Boots star rating = 5). The encapsulation of avobenzone into the TiO/SBA-S lessened cutaneous avobenzone absorption from 0.76 to 0.50 nmol/mg, whereas no reduction was detected for the TiO/SBA-L. The avobenzone-loaded TiO/SBA-S hydrogel exhibited a greater improvement in skin barrier recovery and proinflammatory mediator mitigation compared to the SBA-S hydrogel (without TiO). The cytokines/chemokines in the photoaged skin were reduced by two- to three-fold after TiO/SBA-S treatment compared to the non-treatment control. Our data suggested that the mesoporous formulation with low porosity and a specific surface area showed effective adsorbability and UVA protection, with reduced UVA filter absorption. The versatility of the developed mesoporous system indicated a promising potential for outdoor skin protection.