Journal
ELECTROCHEMISTRY COMMUNICATIONS
Volume 12, Issue 10, Pages 1398-1402Publisher
ELSEVIER SCIENCE INC
DOI: 10.1016/j.elecom.2010.07.031
Keywords
NADH oxidation; Phenothiazine; Diazonium salt; Screen-printed electrode
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Funding
- Cluster de recherche Chimie de la Region Rhone-Alpes
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NADH oxidation catalysts are extremely important in the field of electrochemical biosensors and enzymatic biofuel cells. Based on the growing diazonium chemistry, we synthesized the diazonium salt of the well-known NADH mediator toluidine blue O. The electrochemical reduction of the diazonium moiety by cyclic voltammetry onto a screen-printed electrode leads to an electrocatalyst suitable for the oxidation of NADH. The amperometric response for its oxidation shows a maximal current of 1.2 mu A ([NADH] = 100 mu M). Based on electrochemical measurements, the surface coverage is found to be 3.78 x 10(-11) mol cm(-2) and the heterogeneous standard rate constant k(h) is 1.21 +/- 0.16 s(-1). The sensitive layer for the oxidation of NADH is improved by electrografting the diazonium salt with a potentiostatic method. Both the surface coverage and the heterogeneous standard rate constant k(h) are improved and found to be 6.08 +/- 0.63 x 10(-11) mol cm(-2) and similar to 5.02 s(-1), respectively. The amperometric response is also improved by an 8 fold factor, reaching 9.87 mu A ([NADH] = 120 mu M). These remarkably high values for screen-printed electrodes are comparable to glassy carbon electrodes making this method suitable for low-cost bioelectronical devices. (C) 2010 Elsevier B.V. All rights reserved.
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