Melanin for Photoprotection and Hair Coloration in the Emerging Era of Nanocosmetics

Nanotechnology is revolutionizing fields of high social and economic impact. such ashuman health preservation, energy conversion and storage, environmental decontamination, andart restoration. However, the possible global-scale application of nanomaterials is raising increasingconcerns, mostly related to the possible toxicity of materials at the nanoscale. The possibility of usingnanomaterials in cosmetics, and hence in products aimed to be applied directly to the human body,even just externally, is strongly debated. Preoccupation arises especially from the consideration thatnanomaterials are mostly of synthetic origin, and hence are often seen as “artificial” and their effectsas unpredictable. Melanin, in this framework, is a unique material since in nature it plays importantroles that specific cosmetics are aimed to cover, such as photoprotection and hair and skin coloration.Moreover, melanin is mostly present in nature in the form of nanoparticles, as is clearly observable inthe ink of some animals, like cuttlefish. Moreover, artificial melanin nanoparticles share the same highbiocompatibility of the natural ones and the same unique chemical and photochemical properties.Melanin is hence a natural nanocosmetic agent, but its actual application in cosmetics is still underdevelopment, also because of regulatory issues. Here, we critically discuss the most recent examplesof the application of natural and biomimetic melanin to cosmetics and highlight the requirementsand future steps that would improve melanin-based cosmetics in the view of future applications inthe everyday market.