Mimicking Melanin: Nature's Biopolymer of Intrinsic Microporosity as a Therapeutic Material for Tissue Repair

Melanin is a class of essential biopolymer found across plant, animal, bacterial and fungal kingdoms with an astonishing array of functions, including pigmentation, radical scavenging ability, radiation protection, and thermal regulation. Nature synthesizes melanin of five known kinds: eumelanin, pheomelanin, allomelanin, neuromelanin and pyomelanin. Among them, eumelanin (black and brown pigment in dark hair) and pheomelanin (the pigment in red hair) are the two most commonly considered forms. The past two decades have witnessed a flourish of eumelanin-based materials, especially polydopamine. In our own work, we have endeavored to explore synthetic analogues that enhance, extend and build on these biomimetic systems to enrich melanin and melanin-like materials with desirable properties for a range of applications. A key property of interest here is the ability of properly engineered synthetic melanins to perform as high surface area “sponges” for absorbing toxins and to act as an efficient and stable scavenger of radicals. These synthetic porous melanin materials and a variety of modified analogues will be described in terms of their function in tissue repair. Specifically in topical applications for healing damaged skin from chemical and radiation induced injury.