A glucose/O2 biofuel cell based on electrodes modified with liquid-crystalline cubic phases

Ewa Nazaruk ,  Sławomir Smoliński ,  Renata Bilewicz 

Warsaw University, Faculty of Chemistry, Pasteura 1, Warszawa 02-093, Poland

Abstract

The role of biofuel cells is to convert the chemical energy into electrical current using redox enzymes as biocatalysts. The main advantage of this type of fuel cell is the application of natural compounds eg. glucose or ethanol as fuels. To fix the biocatalysts at the electrode surface we applied liquid-crystalline cubic phase. The lipidic cubic phase can be characterized as a curved, non-intersecting bilayer with two unconnected water channels. Monoolein is an example of a lipid forming such a phase. At hydration over 20% the cubic phase is stable in aqueous solutions. Due to the high viscosity and stability in aqueous solutions cubic phases are good matrices for immobilizing enzymes on electrodes, providing electrical contact with electrode surface and protecting them against denaturation. To increase the rate of the electron transfer from the enzyme to the electrode surface several organic and inorganic mediators were tested. As the bioanode, we applied a glassy carbon rod modified with the cubic phase containing glucose oxidase isolated from Aspergillus niger and tetrathiafulvalene, methylene green or ferrocenecarboxylic acid as the mediators. The biocathode was glassy carbon electrode modified with the cubic phase containing laccase from Cerrena unicolor and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) as the mediator. Such biofuel cell uses glucose as the anode fuel and dioxygen as the cathode fuel. We determined the main parameters of the presented biofuel cells. The load in the range of 10 kΩ to 10 MΩ was applied to determine the cell current (Icell) and the cell voltage (Vcell). When tetrathiafulvalene and ABTS were used as mediators, the biofuel cell has a 0.45 V open circuit potential and 50 mA cm-2 circuit current density in phosphate buffer (pH 7.0) containing 15 mM glucose and saturated with dioxygen at room temperature. The maximum power density reached 7 mW cm-2 at 0.25 V.

 

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Presentation: Poster at SMCBS'2007 International Workshop, by Ewa Nazaruk
See On-line Journal of SMCBS'2007 International Workshop

Submitted: 2007-09-03 15:48
Revised:   2009-06-07 00:44