Fluorescence properties of natural eumelanin biopolymer

Results about fluorescence spectroscopy of natural eumelanin are presented and compared to analogous results related to synthetic eumelanin, with the aim to investigate the structural organization of eumelanin and the role of the protein coat in its optical and structural properties. The spectra of synthetic and natural eumelanin have similar optical spectra, except for the features related to proteins in natural eumelanins. Fluorescence due to ensembles of large oligomer systems has been spectrally distinguished from that due to monomers and small oligomer systems. Nonetheless, the natural (protein-containing) eumelanin results to consist of aggregates having a larger size than that of synthetic eumelanin.