Mediator-modified electrodes for catalytic NADH oxidation: high rate constants at interesting overpotentials

Area of Science:

• Electrochemistry
• Analytical Chemistry
• Materials Science

Background:

• Carbon paste electrodes (CPEs) are widely used in electrochemical applications.
• Developing efficient mediators for NADH oxidation is crucial for biosensors and enzymatic assays.
• Nitrofluorenone derivatives offer potential as redox mediators.

Purpose of the Study:

• To modify carbon paste electrodes with a 2,4,7-trinitro-9-fluorenone derivative adsorbed on zirconium phosphate (ZP).
• To investigate the electrochemical and electrocatalytic properties of the modified electrode for NADH oxidation.
• To evaluate the efficiency of the modified electrode as a mediator for NADH oxidation.

Main Methods:

• Electrochemical reduction of the nitrofluorenone derivative on ZP-modified CPEs.
• Cyclic voltammetry (CV) to study redox behavior and electrocatalysis.
• Rotating disk electrode (RDE) methodology to determine kinetic parameters.
• Evaluation of the second-order rate constant for NADH oxidation.

Main Results:

• The modified electrode demonstrated efficient electrocatalytic NADH oxidation after electrochemical reduction.
• The mediator exhibited a formal potential of approximately +250 mV vs. Ag/AgCl.
• The second-order rate constant for the reaction with NADH exceeded 10^6 M^-1 s^-1.
• The oxidation process approached true diffusion-controlled currents.

Conclusions:

• The ZP-supported, electrochemically reduced nitrofluorenone derivative is a highly effective mediator for NADH oxidation.
• The developed modified electrode shows promise for sensitive and efficient NADH detection.
• The high rate constant suggests potential for applications in electrochemical biosensing.