Fluorescence spectroscopy of eumelanins

The fluorescence spectra from different forms of melanin, excited by an argon-ion laser at 488 nm wavelength were measured. The fluorescence intensity and maxima were found to be dependent on the melanin concentration. The location of the fluorescence maxima depends on the type of melanin and its environment. Solubilization of melanin markedly increases its fluorescence emission and it is postulated that an oxidative cleavage of the quinoid structure of the indole moiety present in the melanin is associated both with the solubilization of the pigment as well as with an enhancement of fluorescence.