Melanin is a kind of ubiquitous natural pigment, which
serves a variety of protective functions in many organisms. In the present
study, natural melanin and synthetic melanin nanoparticles (NPs) were
systematically investigated for its potential application in polymeric
optical materials. A significant short-wavelength shielding and high
visible light transparency polymer nanocomposite was easily obtained via
tuning the melanin particle size. In particular, the nanocomposite film
with melanin NPs (diameter ? 15 nm) loading even as low as 1 wt %
blocks most ultraviolet light below 340 nm and still keeps high visible
light transparency (83%) in the visible spectrum. More importantly,
because of the excellent photoprotection and radical scavenging
capabilities of melanin, the resulting polymer nanocomposite exhibits
outstanding photostability. In effect, such fantastic melanin NPs is
promising for applications in various optical materials.