2, University of Strathclyde, Glasgow, , United Kingdom
3, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States
Melanins are a family of heterogeneous polymeric pigments that provide UV protection, structural support, coloration and free radical scavenging. Formed by oxidative oligomerization of catecholic small molecules, the physical properties of these materials are influenced by covalent and non-covalent disorder. We report the use of tyrosine-containing tripeptides as tunable precursors for polymeric pigments. In these structures, phenols are presented in a (supra-)molecular context dictated by the peptide sequence by repositioning amino acids. Oxidative polymerization can be tuned in a sequence dependent manner resulting in peptide sequence-encoded properties such as UV absorbance, morphology, coloration and electrochemical properties over a considerable range. Short peptides have low barriers to application and can be easily scaled, suggesting near-term applications in cosmetics and biomedicine.