Estimation of molar absorptivities and pigment sizes for eumelanin and pheomelanin using femtosecond transient absorption spectroscopy.

Published

Journal Article

Fundamental optical and structural properties of melanins are not well understood due to their poor solubility characteristics and the chemical disorder present during biomolecular synthesis. We apply nonlinear transient absorption spectroscopy to quantify molar absorptivities for eumelanin and pheomelanin and thereby get an estimate for their average pigment sizes. We determine that pheomelanin exhibits a larger molar absorptivity at near IR wavelengths (750 nm), which may be extended to shorter wavelengths. Using the molar absorptivities, we estimate that melanin pigments contain approximately 46 and 28 monomer units for eumelanin and pheomelanin, respectively. This is considerably larger than the oligomeric species that have been recently proposed to account for the absorption spectrum of eumelanin and illustrates that larger pigments comprise a significant fraction of the pigment distribution.

Full Text

Duke Authors

Cited Authors

  • Piletic, IR; Matthews, TE; Warren, WS

Published Date

  • November 2009

Published In

Volume / Issue

  • 131 / 18

Start / End Page

  • 181106 -

PubMed ID

  • 19916591

Pubmed Central ID

  • 19916591

Electronic International Standard Serial Number (EISSN)

  • 1089-7690

International Standard Serial Number (ISSN)

  • 0021-9606

Digital Object Identifier (DOI)

  • 10.1063/1.3265861

Language

  • eng