Voltammogram of glucose

Fig.2. Hydrodynamic voltammogram of glucose. Constructed from the peak height of the flow injection response. The electrode was reconditioned via potential program (-200 to +700 to 450 mV, 15 minutes at each step) between each change of potential. Flow rate 1 ml/min, injection volume 65 /il, analyte ImM glucose in 1 M NaOH, carrier stream 1 M NaOH.

Figure 4.3 Cyclic voltammogram of glucose at gold electrode in 0.1 M NaOH. Conditions 900 rpm rotation speed, 200 mV s scan rate.

Figure 8.10 Cyclic voltammogram of glucose (c= 166mg/L) on a gold working electrode. (Scattered line ground electrolyte, 0.1 mol/L NaOH sweep rate 200mV/s [17]).

Figure 4. Cyclic voltammogram of glucose oxidase encapsulated ormosil in absence (1) and the presence (2) of 150 mM glucose acid in 0.1 M phosphate buffer pH 7.1 containing 5 mM ferrocene monocarboxylic acid at the scan rate of 5 mV/s.

Figure 2. Cyclic voltammograms of glucose oxidase adsorbed at pyrolytic carbon. 0.1 mol/1 acetate buffer pH 5.5, sweep rate 50 mv/s. 1-Bare electrode, 2-native GOD, 3-heat-denatured GOD.

Electron transfer of the glucose oxidase/polypyrrole on the electrode surface was confirmed by differential pulse voltammetiy and cyclic voltammetry. The glucose oxidase clearly exhibited both reductive and oxidative current peaks in the absence of dissolved oxygen in these voltammograms. These results indicate that electron transfer takes place from the electrode to the oxidized form of glucose oxidase and the reduced form is oxidized by electron transfer to the electrode through polypyrrole. It may be concluded that polypyrrole works as a molecular wire between the adsorbed glucose oxidase and the platinum electrode. 

Fig. 14 Cyclic voltammograms of ferrocene-modified glucose oxidase with (—) and without (—) glucose...

In both cases, the surface concentration of cosubstrate is on the order 10-11 mol cm-2. In each case the voltammogram passes from a reversible surface waveshape to a plateau shape upon addition of glucose. The inverse of the plateau current varies linearly with the inverse of glucose concentration, as shown in Figures 5.25 and 5.26. 

In this connection, Figure 34 shows the cyclic voltammogram of an aqueous solution of ferrocencarboxylic acid and glucose before (a) and after (b) the addition of glucose oxidase.62... 

Figure 34 Cyclic voltammograms recorded at a pyrolitic graphite electrode in an aqueous solution (pH 7) containing (a) [(r -CsHs)Fe(rf-C5H4COOH)] (0.5 mM) and D-glucose (50 mM) (b) after the addition of glucose oxidase (10.9 nM). Scan rate 0.001 Vs 1...

Fig. 7.16 Cyclic voltammograms of electrodes modified with (a) native GOD (or without GOD) (b) GOD containing 12 electron relays (c) as in (b) but in the presence of 0.8 mM glucose and (d) 5 mM glucose (adapted from Heller, 1999)...

Figure 9.2 Cyclic voltammograms for the oxidation of glucose (1 mM) at (a) MPTMS-modified polycrystalline Au electrode (b) MPTMS-AuNP electrode (c) MPTMS-eAuNP electrode in 0.1 M PBS. Scan rate 10 mV s 1.15 (Reprinted with permission fromB. K. Jena and C. R. Raj, Chem. Eur. J. 2006,12, 2702-2708. Copyright Wiley-VCH-Verlag GmbH Co. KGaA.)...

Figure 1. Cyclic voltammogram of a glass thin-layer cell in 1.0 M sodium phosphate/5 mM glucose/10 5 M NaCl/13.4 nM GOx (pH 5.2) under air. Reference RHE. a. First sweep (start time 7.0 min after the addition of GOx). b. Second sweep (start time 50.0 min after the addition of GOx). c. Third sweep (start time 82.0 min after the addition of GOx). Inset Solid line Fifth scan (start time 310.0 min after the addition of GOx). Broken line Sixth scan (start time 707.0 min after the addition of GOx).

Figure 3. Cyclic voltammogram of a GOx-PPNVP/PEUU thin-layer cell in 0.2 M sodium phosphate/5 mM (3-D(+)-glucose (pH 5.2) under air. Reference RHE. Solid line first sweep. Broken line second sweep.

Figure 3. The enantioselective bioelectrocatalyzed oxidation of glucose by glucose oxidase at an electrode modified by a chiral electron-transfer mediator. (A) Organization of the chiral ferrocene monolayer-modified Au electrode and its interaction with soluble GOx. EDC = l-(3-dimethylami-nopropyl)-3-ethylcarbodiimide hydrochloride. (B) Cyclic voltammograms of the ferrocene-modified electrode (curves a and b for (i )-Fc (2) and (5)-Fc (3), respectively) in the presence of 1 x 10 M GOx and 50 mM glucose 0.1 M phosphate buffer, pH 7.0 potential scan rate, 5 mV s electrode area, 0.26 cm. ...

Figure 6. Electrical wiring of glucose oxidase with ferroeene units tethered to lysine residues of the protein backbone (cf. Figure 5B). (A) Cyelic voltammograms of a bare Au electrode in the presence of modified GOx (10 mg mL ) and glucose at (a) 0, (b) 0.8 and (c) 5 mM. Experiments were performed in 0.085 M phosphate bulfer, pH 7.0, under argon. (B) Glucose concentration dependence of the current at 0.26 V vs. SCE developed by the biocatalytic system (using a larger electrode). Adapted from Ref. [83] with permission.

Figure 7. Cyclic voltammograms of a bare Au electrode in the presence of glucose oxidase with ferrocene units covalently tethered to lysine residues (cf. Figure 5D)...

Figure 9. (A) The preparation of a nonordered polymeric layer of glucose oxidase electrically wired by ferrocene groups incorporated in the polymer film. (B) Cyclic voltammograms of the GOx/ferrocene-modified electrode in the absence (a) and presence (b) of glucose, 30 mM. Performed under argon, in phosphate buffer, pH 7 potential scan rate, 10 mV s. Inset calibration curve for the amperometric response to glucose at 0.35 V vs. SCE measured under N2(a) and air (b). Adapted from Ref. [90] with permission.

Figure 10. (A) The stepwise assembly and electrical contacting of a cross-linked organized multilayer array of glucose oxidase (GOx) on an An electrode. (B) Cyclic voltammograms of the GOx/ ferrocene-modified electrode in the presence of glucose (20 mM) in (a) one-, (b) four- and (c) eight-layer configurations. Inset amperometric responses of the four-layer GOx array at 0.4 V vs. SCE as a function of glucose concentration. Recorded in 0.1 M phosphate buffer, pH 7.3, under argon.

Figure 17. (A) The preparation of an electrically wired enzyme by the reconstitution technique, involving the removal of the native FAD cofactor from the enzyme (e.g., GOx) and the incorporation of the artificial FAD-ferrocene dyad into the apo-enzyme. (B) Cyclic voltammograms of a system consisting of ferrocene-FAD-reconstituted GOx (1.75 mg mL ) at various concentrations of glucose (a) 0, (b) 1, (c) 3 and (d) 20.5 mM. Experiments were performed in 0.1 M phosphate buffer, pH 7.3, at 35 C, using a cystamine-modified Au electrode, potential scan rate 2 mV s , under argon. Inset calibration curve of the biocatalytic current (0.5 V vs. SCE) at different glucose concentrations.

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