Advances in Inorganic Nano Sunscreens for UV Protection and Biocompatibility Enhancement

Excessive ultraviolet (UV) radiation increases skin disease risk, which is a global health issue. Sunscreen is an effective way to reduce UV radiation. While inorganic nano ZnO and TiO2 have occupied partial sunscreen market in recent years due to their high efficiency and good photostability, there is still improvement space in sunscreen efficiency, biological safety and customization. This paper reviews the recent literature on inorganic nano sunscreen modification. To improve sunscreen performance, the inorganic nanoparticles can be loaded on scaffold materials or doped with specific metal elements. For their biological safety, modification with certain natural polymers to eliminate reactive oxygen species (ROS) and the size/structure control to decrease skin penetration are effective. Adding dark-colored materials and skin-care materials to inorganic nano sunscreen formulations helps them better commercialization. However, most of these studies are still in the laboratory stage, requiring further research. Hopefully, more enhancement mechanisms and available modification materials are expected to be developed in the future.