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 that aggregate particles are composed of smaller particles with dimensions on the order of 15-30 nm. A related image on a larger scale shows the aggregate of roughly spherical particles 100-200 nm in diameter, a feature commonly found in the sample. Image courtesy of John Simon and Christine Clancy, Duke University.