The supramolecular structure of melanin

Watt, Andrew A. R., Bothma, Jacques P. and Meredith, Paul (2009) The supramolecular structure of melanin. Soft Matter, 5 19: 3754-3760. doi:10.1039/b902507c

Author Watt, Andrew A. R.
Bothma, Jacques P.
Meredith, Paul
Title The supramolecular structure of melanin
Journal name Soft Matter   Check publisher's open access policy
ISSN 1744-683X
Publication date 2009-07-28
Year available 2009
Sub-type Article (original research)
DOI 10.1039/b902507c
Open Access Status Not Open Access
Volume 5
Issue 19
Start page 3754
End page 3760
Total pages 6
Editor Carol Steiner
Place of publication Cambridge, United Kingdom
Publisher Royal Society of Chemistry
Collection year 2010
Language eng
Abstract The melanins are an important class of multifunctional bio-macromolecules with fascinating and potentially useful electronic and optoelectronic properties. They are one of the last major bio-macromolecular systems where we do not know how the constituent molecules organise. This knowledge gap hinders attempts to map their properties and function and is a particular issue in understanding their roles in human photoprotection and melanoma cancer. In this article we provide strong and direct evidence of supramolecular organisation in both natural and synthetic eumelanins. Using low voltage–high resolution transmission electron microscopy (LVHRTEM) we show that sheets of protomolecules stack to form onion-like nanostructures. The inter-sheet spacings within these structures are between 3.7 and 4.0 consistent with non-covalent – stacking in heteroaromatic systems. This type of arrangement has previously been suggested by reciprocal space scattering studies, but our real-space microscopic analysis provides the definitive evidence and dimensions. Furthermore, we show that key photophysical properties of melanin related to their role as photoprotectants are derived from the system's primary chemical structure rather than supramolecular organisation. We now have a framework for the secondary structure of melanins upon which biologically relevant structure–function relationships can be built and new bio-inspired optoelectronic materials and multifunctional coatings can be designed and realised.
Keyword Pi--stacking interactions
Q-Index Code C1
Q-Index Status Confirmed Code

Document type: Journal Article
Sub-type: Article (original research)
Collections: Centre for Organic Photonics and Electronics
School of Mathematics and Physics
2010 Higher Education Research Data Collection
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Citation counts: TR Web of Science Citation Count  Cited 79 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 79 times in Scopus Article | Citations
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Created: Wed, 24 Mar 2010, 15:34:23 EST by Jenny Robinson on behalf of Physics