Enzymatic oxidation of tyrosine enantiomers into biomimetic pigments with enhanced performance for hair dyeing

Most natural biomolecules have two enantiomeric forms and can exist in either of them. Despite the L-type homochirality of natural biopolymers composed of amino acids, a great deal of effort has been devoted to the systems in which chirality dictates molecular self-assembly and corresponding properties. Previously, we demonstrated that chemical pre-modification of tyrosine (L-Tyr) inspired by natural eumelanin can obtain colorful pigments and surface coatings, but their characteristics like stability still have development space. Here, the racemic reaction systems of tyrosine derivatives (L/D-Tyr, Boc-L/D-Tyr and Cbz-L/D-Tyr) were designed, and we proved that substrate molecular chirality can affect the reaction rate of the oxidation process, change the intermolecular force and arrangement during assembly, thus influencing the morphology, structures, and properties of the biomimetic pigment materials. At the same time, we found that L + D-tyrosine derivatives can be oxidized and deposited on hair surfaces to obtain the color effect of black and red-brown series, and achieve green-safe biological hair dyeing. Compared with previous studies, it has faster coloring speed, higher color saturation, stronger color fixation stability, good mechanical strength and biocompatibility, providing a new idea for the manufacture of chiral-inspired advanced materials with bio-nanotechnology applications.