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Ultraviolet (UV) absorbents have been used in sunscreen products in the cosmetic industry, showing adverse effects like rising skin irritation and huge toxicological risks. Although nanostructured lipid carriers (NLCs) are regarded as the potential delivery systems for increasing the amount of encapsulated sunscreen agents and playing UV synergistic effect, the overall synergistic ability is insufficient to meet the industrial demand. In the current study, we optimized a new type of sunscreen composite carrier formulation, the SiO2-NLC nanocomposites carrying ethyl methoxycinnamate (OMC) (OMC/SiO2-NLC), describing their features and functional performance. The OMC/SiO2-NLC nanocomposites are emerging sunscreen systems for cosmetic applications, which combine the advantages of both SiO2 and NLCs. The OMC/SiO2-NLC products, as compared to the ordinary cosmetic emulsion, were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscope, and UV spectrophotometer. In addition, the nanocomposites were also tested for safety and functional properties. The results showed that the OMC/SiO2-NLC particles could effectively encapsulate the sunscreen, in which the encapsulation efficiency reached 76%. The UV absorbance value of the OMC/SiO2-NLC composite carrier containing the same amount of OMC was significantly increased compared with OMC/NLC. The composite carrier's sun protection factor (SPF) increased 56.7%. Photostability of the OMC/SiO2-NLC particles maintained stability for more than 10 hours under UV radiations. The SiO2-based nanocomposites showed better biocompatibility and UV synergistic performance. Therefore, the optimized composite carrier was a suitable nanocomposite for cosmetic applications. [ABSTRACT FROM AUTHOR]

AbstractThe high hydrophilicity of titanium dioxide (TiO2) caused by surface hydroxyl groups limited their application in Pickering emulsions. Inspired by the structure and function of mussel adhesion protein, polydopamine-modified TiO2 (PDA-TiO2) was successfully prepared in this study. The effect of modified conditions on emulsifying capacity of Pickering emulsions stabilized by PDA-TiO2 were investigated, including pH, material ratio, reaction time, and temperature. The morphology and structure properties of modified TiO2 were characterized by SEM, TEM, FTIR, UV, TG, XPS, and XRD. The results suggested that PDA were successfully bonded to the TiO2 surface, which might improve the hydrophilicity of TiO2. PDA-TiO2 could stabilized Pickering emulsion with more uniform emulsified drops when m(TiO2)/m(DA) was 1/0.1, the reaction pH was 8.5, the reaction time was 3 h, and the reaction temperature was 50 °C. In addition, the introduction of polydopamine effectively improved the sun protection ability of TiO2. Compared to traditional sunscreen emulsion, Pickering emulsion stabilized by polydopamine-modified TiO2 could increase the sunscreen value by 55%, which broadened its application in cosmetic and other fields. [ABSTRACT FROM AUTHOR]