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Lipidic cubic phase for immobilising enzymes on electrodes
|Ewa Nazaruk , Renata Bilewicz|
Warsaw University, Faculty of Chemistry, Pasteura 1, Warszawa 02-093, Poland
Lipidic cubic phase is used for the immmobilization of enzymes on the electrode surface. The lipidic cubic phase can be characterised as a curved, non-intersecting bilayer with two unconncted water channels. Monoolein (MO) is an example of a lipid forming such a phase. At hydration over 20%, the cubic phase is stable in aqueous solutions. MO was mixed with water in 64/36% ratio.
In cubic phase, the diffusion of both hydrophobic and hydrophilic compounds can take place. Due to high viscosity and stability in aqueous solutions cubic phases are good matrices for immobilizng enzymes on electrodes and providing electric contact with electrode surface. Additionally, they stabilise membrane enzymes and protect them against denaturation.
Glucose oxidase, pyranose oxidase and laccase were immobilized in water-monoolein cubic phase. Their activity was monitored using cyclic voltammetry. Catalytic oxidation of β-D-glucose at the platinum electrode covered with cubic phase containing glucose or pyranose oxidases leads to hydrogen peroxide. Its oxidation was detected amperometrically. Reduction of oxygen was catalyzed using laccase as the biocatalyst.
The mediators can diffusionally shuttle electrons between the electrode and enzymes and improve the electric contact between them. Hexaammineruthenium(II) chloride and ferrocenecarboxylic acid were used as mediators for processes catalyzed by glucose oxidase and pyranose oxidase. ABTS and hydroquinone were the mediators for laccase catalyzed reduction of oxygen.
Presentation: Poster at SMCBS'2005 Workshop, by Ewa Nazaruk
See On-line Journal of SMCBS'2005 Workshop
Submitted: 2005-07-30 13:28 Revised: 2009-06-07 00:44