Elucidation of the chemical composition of avian melanin

Melanin is the most pervasive and widespread pigment in living organisms and creates a broad range of black, brown and grey colors. Melanin possesses an intriguing set of physical and chemical properties including broadband monotonic absorbance, extremely low radiative quantum yield, and surprising condensed-phase electrical and photoconductive properties. This has led to the suggestion that melanin could be useful as a bio-inspired material in applications such as bioelectronics, chemical sensing, and photon detection. Avian feathers have an unparalleled diversity of melanin-based color that mirrors a diversity in their chemistry. The two chemical variants of integumentary melanin are black eumelanin and rusty red (rufous) pheomelanin. Both types are produced within organelles called melanosomes that are deposited directly from melanocytes into the developing integumentary structure (i.e. skin, hair or feather). While the morphology of melanosomes from feathers is statistically associated with their color and may play a role by means of scattering, it is their chemistry that predominantly determines their reected color. A number of analytical techniques have been applied to decipher melanin's chemical structure, including mass spectrometry, the method used here. However, to the best of our knowledge, the results