Skin Pigmentation-Inspired Polydopamine Sunscreens

Commercial sunscreens usually rely on multiple component formulas against solar irradiation, including UV filters, antioxidants, and nanomaterial matrices. While many efforts are devoted, concern has arisen that the effectiveness and safety issues of most sunscreens are largely limited by their complex formulations, photostability, and toxicity. Inspired by skin pigmentation as primary photoprotective mechanism in human body, novel sunscreen products based on polydopamine (PDA) gels, with a bioinspired protection concept and improved photoprotective capacities, were rationally designed and facilely prepared. The diverse formula of those sunscreen gels can be achieved by the use of PDA nanoparticle, a kind of naturally melanin mimics, to complex/conjugate with different polymers. The resulting PDA sunscreens are bioadhesive, water resistant, and nonskin penetration, yet can be directly removed by towel wiping. They also perform many promising features including superior UV shielding properties, high in vitro and in vivo UV protection efficiencies, nonphototoxicity, and nonirritating nature. These PDA materials in an initial proof-of-concept study were described and it is proposed that this class of bioinspired gels will be useful for incident UV protection where simple, safe, and efficient sunscreens are still highly desirable.