Heavy Water as a Probe of the Free Radical Nature and Electrical Conductivity of Melanin

Rienecker, Shermiyah B., Mostert, A. Bernardus, Schenk, Gerhard, Hanson, Graeme R. and Meredith, Paul (2015) Heavy Water as a Probe of the Free Radical Nature and Electrical Conductivity of Melanin. Journal of Physical Chemistry B, 119 48: 14994-15000. doi:10.1021/acs.jpcb.5b08970


Author Rienecker, Shermiyah B.
Mostert, A. Bernardus
Schenk, Gerhard
Hanson, Graeme R.
Meredith, Paul
Title Heavy Water as a Probe of the Free Radical Nature and Electrical Conductivity of Melanin
Journal name Journal of Physical Chemistry B   Check publisher's open access policy
ISSN 1520-6106
1520-5207
Publication date 2015-11-18
Year available 2015
Sub-type Article (original research)
DOI 10.1021/acs.jpcb.5b08970
Open Access Status Not Open Access
Volume 119
Issue 48
Start page 14994
End page 15000
Total pages 7
Place of publication Washington, DC United States
Publisher American Chemical Society
Language eng
Formatted abstract
Melanins are pigmentary macromolecules found in many locations throughout nature including plants and vertebrate animals. It was recently proposed that the predominant brown-black pigment eumelanin is a mixed ionic–electronic conductor which has led to renewed interest in its basic properties as a model bioelectronic material. This exotic hybrid electrical behavior is strongly dependent upon hydration and is closely related to the free radical content of melanin which is believed to be a mixed population of two species: the semiquinone (SQ) and a carbon-centered radical (CCR). The predominant charge carrier is the proton that is released during the formation of the SQ radical and controlled by a comproportionation equilibrium reaction. In this paper we present a combined solid-state electron paramagnetic resonance (EPR), adsorption, and hydrated conductivity study using D2O as a probe. We make specific predictions as to how the heavy isotope effect, in contrast to H2O, should perturb the comproportionation equilibrium and the related outcome as far as the electrical conductivity is concerned. Our EPR results confirm the proposed two-spin mechanism and clearly demonstrate the power of combining macroscopic measurements with observations from mesoscopic probes for the study of bioelectronic materials
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes epub ahead of print

 
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Created: Fri, 20 Nov 2015, 23:08:02 EST by Mrs Louise Nimwegen on behalf of School of Chemistry & Molecular Biosciences