Coral-friendly and non-transdermal polymeric UV filter via the Biginelli reaction for in vivo UV protection

Sunscreen is recommended to protect human skin from ultraviolet (UV) radiation damage and cancer development. However, small-molecule organic UV filters in sunscreens damage the environment and may pose a health risk to users through transdermal action because of their small molecular weights. Here we report a strategy for realizing safe and coral-friendly polymeric UV filters by combining the Biginelli reaction and free radical polymerization. We have obtained a water-soluble polymer with excellent UV absorbance that effectively protects mice from UV radiation-induced skin burn considerably better than well-known UV filters (e.g., oxybenzone and avobenzone) and commercial sunscreens. This polymer is non-transdermal owing to its high molecular weight and is nearly harmless to algae, corals, and mice. This work presents an initial exploration of biofriendly and coral-friendly polymeric UV filter via a simple multicomponent reaction and provides insights that can guide the design of value-added functional polymers for practical applications.