Infrared‐Scattering by Programmable Peptide‐Melanin Microparticles

Natural melanin polymers, biosynthesized from free tyrosine, assemble into microstructures that interact with light, producing a wide range of photonic properties. These structures are formed by mechanisms that are difficult to control to create new optical materials. Here, simple pentapeptides YXXXY is presented, where the XXX controls self‐assembly into microstructures, after which the Y's are polymerized by tyrosinase into melanin. It sought to computationally predict peptides that will assemble into two‐layer films that exhibit structural color and infrared (IR) scattering. Three peptides (YPIIY, YLPIY, YVPAY) are synthesized and found to form a two‐layer film exhibiting structural color. YLPIY‐melanin also forms a stable coating with scattering peaks in the near‐ and mid‐IR. This coating reduces the signature of a hotplate (37 °C) as seen by a thermal camera. This synthetic peptidic material is the first to exhibit IR‐scattering, opening the possibility of incorporating this function into bio‐compatible fibers, textiles, and plastics.