A Microparticle Sunscreen with Highly Effective ROS Scavenging and Nonpenetration.

The health risks of overexposure to ultraviolet (UV) rays have been recognized, but some controversy still exists regarding the benefits and safety of commercially available sunscreens. Exposure to UV filters may directly result in serious health problems, such as skin penetration, cytotoxicity and the production of carcinogenic reactive oxygen species (ROS). Here, organic UV-filter self-framed microparticles (SFMPs) were developed, in which a small organic UV filter, antioxidant and hexachlorocyclotriphosphazene were self-assembled into microparticles by one-pot precipitation polycondensation without any vehicles/carriers. The resultant SFMPs could prevent UV irradiation and have strong ROS scavenging ability, while significantly reducing skin penetration. Furthermore, incorporating small molecules into the microparticles can prevent direct contact between the epidermis and the small UV filter, overcome the problems of self-instability and poor solubility of the antioxidant, and solve the issue of nanoparticle aggregation. Moreover, SFMP microparticles exhibit attractive UV-shielding performance in vivo and in vitro without toxicity. Therefore, we speculate that the self-framed SFMPs with outstanding ROS scavenging ability and excellent UV protection performance will have a promising application in the field of sunscreens.