Bioinspired nanoparticles prevent blue-light-induced skin hyperpigmentation via FZD2-TYR-melanin pathway

Melanin is the natural physiological defense for skin, but excessive melanin production can result in conditions like hyperpigmentation and melasma. In addition to UV light, visible light, especially blue light, has been recognized as an extra factor contributing to cutaneous hyperpigmentation and premature photoaging. However, there are currently no effective protective agents against blue light. Within this research, we obtained polydopamine nanoparticles (PDA NPs) and cuttlefish ink nanoparticles (CINPs), which are inspired by endogenous melanin. Our research confirmed that PDA NPs and CINPs shared similar structural and functional properties with natural melanin. Otherwise, these nanoparticles not only exhibited excellent photostability and broad-spectrum ultraviolet-visible light absorption capabilities but also possessed superb biocompatibility and antioxidant properties. Experiments conducted in vitro and in vivo verified that PDA NPs and CINPs could effectively hold back melanin production and alleviate pigmentation. Furthermore, we found that the underlying mechanism by which PDA NPs and CINPs reduced melanin formation was through inhibition of the FZD2-TYR-melanin signaling pathway. Taken together, our findings not only demonstrate that PDA NPs and CINPs are powerful anti-blue light agents but also provide an in-depth mechanism of these nanoparticles in the inhibition of pigment formation.