Colorful Pigments for Hair Dyeing Based on Enzymatic Oxidation of Tyrosine Derivatives

Melanin exists widely in nature and can afford a variety of colors from black to brown and red according to chemical structure differences and specific mixtures. Inspired by nature, this work reports that tyrosine derivatives with different protecting groups at its N- or C-terminal can be enzymatically oxidized into melanin-like pigments with a wide range of colors. The emergence of colorful pigments can be attributed to the incomplete enzymatic oxidation and polymerization caused by the chemical premodification of the tyrosine molecule. The pigments can be deposited on the surface of the hair to obtain a series of colorful and saturated hair dye effects. Moreover, after the pigments were coated on the hair, we can further deposit silver nanoparticles through in situ reduction, making these coatings have anti-inflammatory and antibacterial potential, thereby expanding their potential use for people with low immunity or those who work in hospitals. This work proposes a green and effective way to synthesize colorful pigments with great potential applications in the hair dying and cosmetic industries.