Melanin‐Inspired Chromophoric Microparticles Composed of Polymeric Peptide Pigments

Melanin and related polyphenolic pigments are versatile functional polymers that serve diverse aesthetic and protective roles across the living world. These polymeric pigments continue to inspire the development of adhesive, photonic, electronic and radiation‐protective materials and coatings. The properties of these structures are dictated by covalent and non‐covalent interactions in ways that, despite progress, are not fully understood. It remains a major challenge to direct oxidative polymerization of their precursors (amino acids, (poly‐)phenols, thiols) toward specific structures. By taking advantage of supramolecular pre‐organization of tyrosine‐tripeptides and reactive sequestering of selected amino acids during enzymatic oxidation, we demonstrate the spontaneous formation of distinct new chromophores with optical properties that are far beyond the range of those found in biological melanins, in terms of color, UV absorbance and fluorescent emission. Inspired by melanin diversity and biosynthesis, a method to produce melanin‐like microparticles as a reactive scaffold for subsequent oxidative incorporation of amino acids was developed. The spontaneous formation of distinct new chromophores with optical properties that are far beyond the range of those found in biological melanins, in terms of color, UV absorbance and fluorescent emission is demonstrated.