Mediator-modified electrodes for electrocatalytic oxidation of NADH

Immobilized redox mediators for electrochemical NAD(P)+ regeneration

“…Mediators can be immobilized in polymer films or Nafion® as well as in the electrode material itself (Doaga et al 2009;Gründig et al 1995;Huang et al 2007;Ramirez Molina et al 1999). The redox mediator Meldola's Blue has been entrapped into the non-conductive poly-1,2-diaminobenzene and the conductive poly-3,4-ethylenedioxythiophene (Doaga et al 2009).…”

“…Due to the mediator leakage into the measurement solution, the electrochemical signal was unstable. Gründig et al immobilized different mediators (e.g., N-methyl-phenazinium, 1-methoxy-Nmethyl-phenazinium, and Medola's Blue) as Reinecke salts in graphite-epoxy composites (Gründig et al 1995). A sensor based on this composite electrode retained about 50% of the initial sensitivity after 9,500 measurements of NADH in a buffered system.…”

“…This method had some major drawbacks such as leakage of mediator into the solution and low current densities due to the small amount of mediator available on the electrode surface and was concluded to be inappropriate for the construction of robust sensors. Nevertheless, the problem of leakage could be minimized with the use of an appropriate reactant which reduces the solubility of the mediator, for instance, Reinecke salt when entrapping Meldola's Blue (Gründig et al 1995). The second immobilization strategy studied was the adsorption of the mediator on epoxy-graphite composite electrode surfaces.…”

Electrochemical techniques and sensors for ocean research

“…This film may range from a single molecular layer to several mm thick. Examples of materials used to modify electrodes include mercury for the polarographic determination of trace metals (Devitre et al, 1991), probably the most common electrode modification, conducting polymers (Dhawan et al, 1997), gels (Tercier-Waeber et al, 1998;Tercier-Waeber et al, 1999), polymers loaded with enzymes and redox mediators (Grundig et al, 1995;Bartlett et al, 1998;Cosnier et al, 1999), doped polymers (Trojanowicz et al, 1996), molecular constructions tethered to the electrode surface and nanostructured materials (Evans et al, 2002;Imokawa et al, 2006). The electrodes may be passive as in potentiometry or active as in amperometry and impedimetry.…”

Multidimensional electrochemical imaging in materials science

“…Monitoring of active corrosion by SECM has been realized on a range of materials by identification of locally released species by cyclic voltammetry at the UME or by use of ion-selective potentiometric microelectrodes. The materials investigated include steel [100][101][102], dental fillings [103,104], Si [105], Ti [106,107], alloys [76,[108][109][110][111][112][113], ZnSe wave-guides [114], organic coatings on metallic substrates [115][116][117], AgI-based ion-selective membranes [118], and composite-based amperometric biosensors [119]. Simões et al [120] studied the corrosion behavior of an iron/zinc galvanic couple immersed in aqueous sodium chloride solution.…”