Charge Transport Properties in Eumelanin: Probing the Effect of Hydration on the Ubiquitous Biomacromolecular Pigment via Conductivity, MuSR and EPR Experiments.

Albertus Mostert (2010). Charge Transport Properties in Eumelanin: Probing the Effect of Hydration on the Ubiquitous Biomacromolecular Pigment via Conductivity, MuSR and EPR Experiments. PhD Thesis, School of Mathematics and Physics, The University of Queensland.

       
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Author Albertus Mostert
Thesis Title Charge Transport Properties in Eumelanin: Probing the Effect of Hydration on the Ubiquitous Biomacromolecular Pigment via Conductivity, MuSR and EPR Experiments.
School, Centre or Institute School of Mathematics and Physics
Institution The University of Queensland
Publication date 2010
Thesis type PhD Thesis
Supervisor Prof. Paul Meredtih
A/Prof. Ben Powell
Prof. Ian Gentle
Total pages 227
Total colour pages 39
Total black and white pages 188
Subjects 01 Mathematical Sciences
Abstract/Summary The brown-black pigment eumelanin is one of the most common bio-macromolecules in the biosphere. The biological functions of eumelanin include protection from harmful UV rays and regulating metal ion concentrations to prevent toxicity effects in the human brain. In addition, eumelanin has potential applications as a bio-electronic material with sensing capabilities. However, it is important to understand the structure-property relationship that controls charge transport in eumelanin in order to tailor its properties for such applications. In this work it will be shown that the current paradigm for understanding charge transport in eumelanin, the Mott-Davis amorphous semiconductor model, does not describe eumelanin's electrical properties. Instead, a new model will be proposed based on chemical principles: the comproportionation reaction. This hypothesis is consistent with the hydration dependent adsorption, conductivity, MuSR and EPR experiments reported here. These data will show that with the addition of water, new charge carriers are generated within eumelanin. This self-doping effect leads naturally to the suggestion that eumelanin may be a mixed protonic/electronic conductor. This suggests new possibilities for applications in bio-compatible devices and solid state organic electrochemical transistors.
Keyword eumelanin
charge transport
comproportionation reaction
amorphous semiconductor
hydration dependence
resonance
Additional Notes 44, 53, 73, 75, 81, 82, 88, 89, 92, 93, 110, 112, 114, 132-134, 136, 139, 140, 142, 146, 175, 177, 178, 181-183, 208, 216, 217, 219-227

 
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Created: Wed, 29 Jun 2011, 16:38:31 EST by Mr Albertus Mostert on behalf of Library - Information Access Service