Oxidase Oxide electrode

Carbonaceous substrates (graphite and glassy carbon) are generally preferred because of their mechanical, chemical, and electrochemical properties. Excellent results are also obtained by chemically modified platinum (154,156,179) and tin(IV) oxide electrodes (155). For example, glucose oxidase has been successfully immobilized by cross-linking the enzyme with BSA and GA onto an electrochemically oxidized platinum surface, with silanization using 3-amino-propyltriethoxysilane ... 

Figure 3-6. Cyclic voltammograms corresponding to the bioelectrocatalyzed oxidation of variable concentrations of glucose by the reconstituted glucose oxidase- functionalized electrode shown in Fig. 3-5A. Glucose concentrations correspond to (a) 0 mM, (b) 5 mM, (c) 10 mM, (d) 15 mM, (e) 20 mM, (f) 25 mM, (g) 35 mM, (h) 40 mM (i) 50 mM. Inset Calibration curve corresponding to the transduced electrocatalytic currents at different concentrations of glucose. Reproduced with permission from ref. 32. Copyright 2002 American Chemical Society.

Glucose oxidase, Horseradish peroxidase Silver NP/CNT/Chitosan modified indium tin oxide electrode Glucose biosensor [135]... 

Electrolytic oxidation of sucrose, maltose and glucose on a lead-(II) oxide-coated titanium mesh electrode has been studlgd in connection with electrochemical treatment of effluents. Hydroxide radicals are the effective oxidant in the stepwise photoanodlc oxidation of D-glucose to carbon dioxide on a polycrystalline zinc oxide electrode in alkaline solution. The electrocatalytic oxidation of D-glucose at a glucose oxidase-immobilized benzoquinone-mixed carbon paste electrode has been studied and the Imj ortance of various concentration parameters on the oxidation examined. A comparative study of the electrocatalytic Influence of underpotential heavy... 

Figure 11.39 summarizes the reactions taking place in this amperometric sensor. FAD is the oxidized form of flavin adenine nucleotide (the active site of the enzyme glucose oxidase), and FAD1T2 is the active site s reduced form. Note that O2 serves as a mediator, carrying electrons to the electrode. Other mediators, such as Fe(CN)6 , can be used in place of O2. 

The alcohol tolerance of O2 reduction by bilirubin oxidase means that membraneless designs should be possible provided that the enzymes and mediators (if required) are immoblized at the electrodes. Minteer and co-workers have made use of NAD -dependent alcohol dehydrogenase enzymes trapped within a tetraaUcylammonium ion-exchanged Nafion film incorporating NAD+/NADH for oxidation of methanol or ethanol [Akers et al., 2005 Topcagic and Minteer, 2006]. The polymer is coated onto an electrode modified with polymethylene green, which acts as an electrocatalyst... 

Of direct interest for biofuel cell applications are the reported reduction of O2 by multi-copper oxidases on carbon nanotube electrodes [Yan et al., 2006 Zheng et al., 2006] and the oxidation of H2 by hydrogenase covalently bound to carbon nanotubes [Alonso-Lomillo et al., 2007]. The hydrogenase/nanotube anode is extremely stable (>1 month), and shows 33-fold enhanced enzyme coverage compared with similarly treated graphite of the corresponding geometric surface area. A. vinosum... 

---