Evidence of short-range electron transfer of a redox enzyme on graphene oxide electrodes

Direct electron transfer (DET) between redox enzymes and electrode surfaces is of growing interest and an important strategy in the development of biofuel cells and biosensors. Among the nanomaterials utilized at electrode/enzyme interfaces to enhance the electronic communication, graphene oxide (GO...

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Bibliographic Details
Published in:Physical chemistry chemical physics : PCCP 2014-09, Vol.16 (33), p.17426-17436
Main Authors: Martins, Marccus V A, Pereira, Andressa R, Luz, Roberto A S, Iost, Rodrigo M, Crespilho, Frank N
Format: Article
Language:English
Subjects:
Biosensors
Computer Simulation
Electric Conductivity
Electrodes
Electron transfer
Electron Transport
Electronics
Enzyme Activation
Enzymes
Glucose Oxidase - chemistry
Graphene
Graphite - chemistry
Materials Testing
Models, Chemical
Models, Molecular
Nanomaterials
Oxides
Oxides - chemistry
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Summary:Direct electron transfer (DET) between redox enzymes and electrode surfaces is of growing interest and an important strategy in the development of biofuel cells and biosensors. Among the nanomaterials utilized at electrode/enzyme interfaces to enhance the electronic communication, graphene oxide (GO) has been identified as a highly promising candidate. It is postulated that GO layers decrease the distance between the flavin cofactor (FAD/FADH2) of the glucose oxidase enzyme (GOx) and the electrode surface, though experimental evidence concerning the distance dependence of the rate constant for heterogeneous electron-transfer (k(het)) has not yet been observed. In this work, we report the experimentally observed DET of the GOx enzyme adsorbed on flexible carbon fiber (FCF) electrodes modified with GO (FCF-GO), where the k(het) between GO and electroactive GOx has been measured at a structurally well-defined interface. The curves obtained from the Marcus theory were used to obtain k(het), by using the model proposed by Chidsey. In agreement with experimental data, this model proved to be useful to systematically probe the dependence of electron transfer rates on distance, in order to provide an empirical basis to understand the origin of interfacial DET between GO and GOx. We also demonstrate that the presence of GO at the enzyme/electrode interface diminishes the activation energy by decreasing the distance between the electrode surface and FAD/FADH2.
ISSN:1463-9076
1463-9084
DOI:10.1039/c4cp00452c