Credit: https://doi.org/10.1016/j.xcrp.2023.101308

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. Researchers have developed a prototype for coral-reef-friendly sunscreens by using polymerization to create large molecules that still block UV radiation but are too big to penetrate our skin, coral, and algae. The polymeric UV filter, presented March 1 in the journal Cell Reports Physical Sciences, was more effective at preventing sunburn in mice than existing sunscreens.

They report a strategy for realizing safe and coral-friendly polymeric UV filters by combining the Biginelli reaction and free radical polymerization. They 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 mice that did not absorb the polymer through their skin, nor did they experience any inflammation or other skin damage. The polymer UV filter also appears to be non-hazardous for coral and algae, two groups of organisms that are harmed by currently available chemical sunscreens. Indeed, the same corals tested bleached and died within 6 and 20 days of exposure to oxybenzone.

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.