Melanin Skins Provide UV-Protective Coatings

Melanin is a biopolymer responsible for the color of human eyes, skin, and hair. It also protects us from harmful ultraviolet radiation and oxidative stress. Researchers want to take advantage of these properties by using melanin in protective coatings for electronics and other engineered materials. But natural melanin is tough to work with because of its poor solubility. Chemists have recently developed a synthetic version of melanin that mimics the behavior of the real thing and dissolves in basic aqueous solutions. A team led by Christopher J. Ellison of the University of Texas, Austin, and Jaime C. Grunlan of Texas A&M University has now developed a method that uses solutions of the melanin substitute to deposit protective thin films (ACS Macro Lett. 2015, DOI: 10.1021/acsmacrolett.5b00080). The researchers alternately dipped glass slides into solutions of cationic poly(allylamine hydrochloride), or PAH, and anionic synthetic melanin. They thus built up multiple UV-absorbent PAH-melanin bilayers.