Bioinspired L-Lysine-Doped Polydopamine for Preventing and Treating UV-Induced Skin Damage

Excessive ultraviolet (UV) radiation causes a series of adverse effects on human skin, such as erythema and tanning due to the produce of endogenous melanin of human skin. Inspired by the self-defense mechanism of human skin to prevent UV radiation damage, we construct a natural and biocompatible Carb@PDA−L sunscreen hydrogel by doping melanin-like L-lysine doped polydopamine (PDA−L) to biocompatible poly-γ-glutamic acid based hydrogel matrix Carb, which displays good biosafety, efficient UV shielding performance and excellent antioxidative and anti-inflammatory performance in the application of the skin protection of sun and repair after sunburn. The melanin-like PDA−L can be synthesized by the oxidative polymerization of dopamine triggered by L-lysine under alkali-free condition, which exhibits increase absorption intensity in the UV region and better reactive oxygen species removal performance compared with undoped polydopamine in the perspective of a UV absorber. Meanwhile, PDA−L, as the synthetic analogue of natural melanin, has good biosafety, which can avoid the skin oxidative damage and penetrative toxicity of the conventional sunscreen.