Confinement of Reactive Oxygen Species in an Artificial-Enzyme-Based Hollow Structure To Eliminate Adverse Effects of Photocatalysis on UV Filters

Skin cancers caused by UV irradiation have been a major public health problem. One simple and effective way to avoid the above detrimental effects is the use of UV-protective sunscreens. However, there has been considerable concern with the issue of the production of reactive oxygen species (ROS) through the photodegradation of commercial UV filters. Herein, for the first time, it is reported that the integration of ZnO nanoparticles and CeO_x nanoparticles into hollow microspheres (ZnO/CeO_x HMS) could provide broad-spectrum UV protection and scavenge generated ROS under UV irradiation. Benefiting from the cooperative effect of the hollow structure and the antioxidative activity of CeO_x, ROS generated under UV irradiation could be confined to a limited space and effectively conversion into nontoxic molecules is catalyzed as a consequence of increased collision frequency. Therefore, both primary, direct UV-induced damage and secondary ROS toxicity could be greatly reduced.