Life Sciences Nanotheater

Eumelanin

TappingMode AFM image of dried eumelanin deposited on mica. The eumelanin was obtained from the ink sacs of the Sepia officinalis cuttlefish. Though the molecular structure of eumelanin is unknown, it is known to be a biopolymer formed by the enzymatic polymerization of tyrosine and dopa derivatives. It is also known that both eumelanin particle size and aggregation behavior are important factors in determining eumelanin photochemical behavior. This image shows a feature commonly found in the sample - an aggregate of roughly spherical particles 100-200 nm in diameter. A related image on a smaller scale shows that these particles are in turn composed of particles with dimensions on the order of 15-30 nm. Image courtesy of John Simon and Christine Clancy, Duke University.