Glucose oxidase, scanning electrochemical

The preparation and application of SAM systems patterned by STM and their use in catalysis was demonstrated by Wittstock and Schuhmann [123]. The patterning (local desorption) of SAMs from alkane thiols on gold was performed by scanning electrochemical microscopy (SECM), followed by the assembly of an amino-deriva-tized disulfide and coupling of glucose oxidase to form a catalytically active pattern of the enzyme. The enzymatic activity could be monitored/imaged by SECM. 

Pierce, D. T., Unwin, P. R. and Bard, A. J. (1992), Scanning electrochemical microscopy.17. Studies of enzyme mediator kinetics for membrane-immobilized and surface-immobilized glucose-oxidase. Anal. Chem., 64(17) 1795-1804. 

Burchardt M, Wittstock G. Kinetic studies of glucose oxidase in polyelectrolyte multilayer films by means of scanning electrochemical microscopy (SECM). Bioelectrochem 2008 72 66-76. 

PFg, BF4, polyoxometalates (POMs), and even glucose oxidase (GOD) as the counter-anions (Fig. 4.14a, SWNT-IL-X) [56]. The properties of SWNT and the various anions were facilely and successfully delivered into the resulting compounds. For example, the rich redox activity was also successfully transferred into SWNT-IL-POM merely by a simple and facile anions exchange. The surface-confined SWNT-IL-POM shows three couples of well-defined redox waves at scan rates up to 2 V/s (Fig. 4.14b), which was presumably attributed from electron conduction of SWNT, ionic conduction of IL, and redox conduction of POM. It was unusuai for an often-seen compound in electrochemical systems. 

Fig. 1 Cyclic voltammetry of the catalysis of the electrochemical oxidation of / -D-glucose by glucose oxidase with ferrocene methanol as the cosubstrate. Dashed line ferrocene methanol (0.1 M) alone the same trace is obtained in the presence of glucose oxidase (27 pM) with no glucose present or in the presence of glucose (0.5 M) with no gl ucose oxidase present. Dotted and full lines ferrocene methanoi (0.1 mM) + giucose oxidase(27 pM) + glucose (0.5 M) at pH 4.5 (acetate buffer) and 6.5 (phosphate buffer), respectively. Ionic strength 0.1 M. Scan rate ...

The products of the reaction they catalyze may inhibit many enzymes through Michaelis-Menten kinetic retroaction. Protons, which are involved as products or reactants in a number of cases, may also influence the enzymatic kinetics. The course of the reaction may therefore be altered by the attending production or depletion of protons. It is thus interesting to examine whether these phenomena may be revealed by the effect they might have on the electrochemical responses of immobilized enzyme films under appropriate conditions [92]. A first clue of the existence of such inhibition effects is the observation of hysteresis behaviors of the type shown in Fig. 18(a) where data obtained with 10 glucose oxidase monolayers with ferrocene methanol as cosubstrate have been taken as example. In the absence of inhibition, the forward and reverse traces should be exactly superimposed. Hysteresis increases to the point of making a peak appear on the forward trace as the scan rate decreases and as the concentration of the buffer decreases, as illustrated in Fig. 18c, c , c , c by comparison with Fig. 18(a). 

Fvans, S. A. G. Brakha, K. Billon, M. Mailley, P Denuault, G. Scanning electrochemical microscopy (SFCM) localized glucose oxidase immobilization via the direct electrochemical microspotting of polyp5urole-biotin films. Electrochem. Commun. 2005, 2,135-140. 

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