Monolayer glucose oxidase

FIGURE 5.25. Avidin-biotin construction of a monolayer glucose oxidase electrode with an attached ferrocenium cosubstrate and cyclic voltammetric response in a phosphate buffer (pH 8) at 25°C and a scan rate of 0.04 V/s. a attached ferrocene alone, h In the presence of 0.5 M glucose, c Variation of the inverse of the plateau current with the inverse of substrate concentration. Adapted from Figure 1 in reference 24, with permission from the American Chemical Society. 

I. Willner, V. Heleg-Shabtai, R. Blonder, E. Katz, and G. Tao, Electrical wiring of glucose oxidase by reconstitution of FAD-modified monolayers assembled onto Au-electrodes. J. Am. Chem. Soc. 118, 10321-10322 (1996). 

L. Jiang, C.J. McNeil, and J.M. Cooper, Direct electron transfer reaction of glucose oxidase immobilized at a self-assembled monolayer. J. Chem. Soc. Chem. Commun. 1293-1295 (1995). 

In contrast to the molecular wire of molecular interface, electron mediators are covalently bound to a redox enzyme in such a manner as an electron tunneling pathway is formed within the enzyme molecule. Therefore, enzyme-bound mediators work as molecular interface between an enzyme and an electrode. Degani et al. proposed the intramolecular electron pathway of ferrocene molecules which were covalently bound to glucose oxidase [ 4 ]. However, few fabrication methods have been developed to form a monolayer of mediator-modified enzymes on the electrode surface. We have succeeded in development of a novel preparation of the electron transfer system of mediator-modified enzyme by self-assembly in a porous gold-black electrode as schematically shown in Fig.12 [14]. 

Fig. 13 Self-assembled linkage of ferrocene-modified glucose oxidase (GOD) on thiol monolayer...

Examples of surface-immobilized mediators are electropolymerized azines for electro-oxidation of The extreme form of this approach is formation of biocatalytic monolayer, comprising a surface-bound mediator species that is itself bound to a single enzyme molecule. Katz et al. report a complete cell based on novel architecture at both electrodes (Figure 7). On the anode side, the FAD center of glucose oxidase is removed from the enzyme shell and covalently attached to a pyrroloquinoline quinone (PQQ) mediator species previously immobilized on a gold surface. The GOx apoenzyme (enzyme with active center removed) is reintroduced in solution and selectively binds to FAD, resulting in a PQQ-... 

A C felt sensor coated with a glucose oxidase monolayer was used in an FI manifold in the presence of dissolved potassium hexacyanoferrate as mediator for the on-line determination of interferents [89]. 

S. Campuzano, R. Galvez, M. Pedrero, F.J. Manuel de Villena and J.M. Pingarron, Preparation, characterization and application of alkanethiol self-assembled monolayers modified with tetrathiafulvalene and glucose oxidase at a gold disk electrode, J. Electroanal. Chem., 526(1-2) (2002) 92-100. 

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