ChemInform Abstract: Kinetic Aspects of the Use of Modified Electrodes and Mediators in Bioelectrochemistry

Abstract

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Direct electrochemistry and Os-polymer-mediated bioelectrocatalysis of NADH oxidation by Escherichia coli flavohemoglobin at graphiteelectrodes

“…To overcome these problems modified electrodes were extensively used to reduce the overpotential of the reaction and to maintain fast reaction kinetics. Modified electrodes for NADH oxidation exploit conductive polymers and different types of mediators such as quinones, diimines, flavins, phenothiazines and phenoxazine derivatives, also polymerized (Bartlett and Simon, 2003;Bartlett et al, 1991;Gorton, 1986;Gorton andDominguez, 2002, 2007;Rincon et al, 2010;Sandström et al, 2000). Another approach involves bioelectrocatalytic oxidation of NADH, however, in practice just a few flavoenzymes were successfully applied for direct (unmediated) NADH oxidation (Barker et al, 2007;Kobayashi et al, 1992;Reeve et al, 2012;Zu et al, 2003); otherwise, enzyme wiring to electrodes by a suitable redox mediator was used (Antiochia and Gorton, 2007;Tasca et al, 2008;Tsujimura et al, 2002a).…”

Enhanced direct electron transfer between laccase and hierarchical carbon microfibers/carbon nanotubes composite electrodes. Comparison of three enzyme immobilization methods

“…This three-dimensional composite material (3D-CNT/CMF) was recently fabricated [8] and utilized in bioelectrocatalysis of horseradish peroxidase (HRP) for H 2 O 2 reduction at +600 mV vs. Ag|AgCl [9]. The main advantages for using the 3D-CNT/CMF composite electrode as immobilization surface for laccase consists on: i) avoiding the use of a redox hydrogel film as matrix for the electronic communication between enzyme and electrode, thus eliminating additional limitations such as the electron hopping step [10] and a further drop in the cell potential [11][12][13]; and ii) reduction of the large number of interfacial cascades in-between the individual CNT produced when they are simply dropped onto a supporting electrode in presence or not of a mediator/crosslinking polymeric net [14][15][16], which requires extensive optimization protocols and characterization methods, such as SECM [17,18].…”

Enzymatic Glucose Biofuel Cell and its Application

“…It is important to understand that fast electron transfer between enzymes and electrodes surface is very difficult to achieve because of the fact that the active center is buried deep in the protein shell, which naturally insulates the active center [26]. Currently, two main strategies are employed to overcome this challenge to establish efficient electrical connection between the enzyme and the current collector: Direct Electron Transfer (DET) [27,28] and Mediator Electron Transfer (MET) [29,6] as shown in (Figure 3). DET requires that the active site of the enzyme communicates directly with the electrode surface, whereas MET employs redox couples as mediators to enable communication between both the enzyme and the electrode surface.…”