All-small-molecule Hydrogels for Safe and Efficient Photoprotection.

Long-term exposure to ultraviolet (UV) radiation can cause sunburn, skin aging, and skin cancers. Conventional sunscreens typically combine organic UV filters and inorganic particles for photoprotection, yet concerns remain regarding skin penetration, systemic effects, and reactive oxygen species generation. Inspired by natural photoprotective mechanisms in plants, we develop a series of all-small-molecule sunscreen hydrogels based on natural polyphenols through a facile one-pot assembly process. The resulting hydrogels exhibit efficient UV shielding with high sun protection factors, strong bioadhesion, antioxidant and antibacterial activities, high visible-light transmittance, and low skin penetration tendency. The hydrogels also demonstrate good environmental stability and effective photoprotection in both mice and Bama miniature pigs. This work highlights the potential of bioinspired all-small-molecule assemblies for efficient and safe photoprotection.