Nano Archive

Oxygen-reducing enzyme cathodes produced from SLAC, a small laccase from Streptomyces coelicolor

Gallaway, Joshua and Wheeldon, Ian and Rincon, Rosalba and Atanassov, Plamen and Banta, Scott and Barton, Scott Calabrese (2008) Oxygen-reducing enzyme cathodes produced from SLAC, a small laccase from Streptomyces coelicolor. BIOSENSORS & BIOELECTRONICS, 23 (8). pp. 1229-1235.

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The bacterially-expressed laccase, small laccase (SLAC) of Streptomyces coelicolor, was incorporated into electrodes of both direct electron transfer (]:)ET) and mediated electron transfer (MET) designs for application in biofuel cells. Using the DET design, enzyme redox kinetics were directly observable using cyclic voltammetry, and a redox potential of 0.43 V (SHE) was observed. When mediated by an osmium redox. polymer, the oxygen-reducing cathode retained maximum activity at pH 7, producing 1.5 mA/cm(2) in a planar configuration at 900 rpm and 40 degrees C, thus outperforming enzyme electrodes produced using laccase from fungal Trametes versicolor (0.2mA/cm(2)) under similar conditions. This improvement is directly attributable to differences in the kinetics of SLAC and fungal laccases. Maximum stability of the mediated SLAC electrode was observed at pH above the enzyme's relatively high isoelectric point, where the anionic enzyme molecules could form an electrostatic adduct with the cationic mediator. Porous composite SLAC electrodes with increased surface area produced a current density of 6.25 mA/cm(2) at 0.3 V (SHE) under the above conditions. (c) 2007 Elsevier B.V. All rights reserved.

Item Type:Article
Subjects:Physical Science > Nano objects
Biomedical Science > Nanobiotechnology
Material Science > Bio materials
ID Code:1270
Deposited By:Anuj Seth
Deposited On:15 Dec 2008 14:29
Last Modified:29 Jan 2009 11:34

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