Preparation and performance of SiO2-nanostructured lipid encapsulating sunscreen

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.