Electrochemical redox pattern and allied interactive behaviour of FAD on a ruthenium-modified glassy carbon electrode surface

Abstract

The redox and interactive behaviour of flavin adenine dinucleotide (FAD) with a ruthenium (Ru)-modified glassy carbon electrode (GCE) was investigated. The electron-transfer kinetics on the Ru-modified GCE gives an apparent electron-transfer coefficient, α _app of 0.56, and an apparent heterogeneous electron transfer rate constant, k _app of 2.32 s⁻¹, respectively. The cyclic voltammetry (CV) complemented by alternating cyclic voltammetry (ACV) shows reduction of FAD to be a quasi-reversible reaction involving FAD adsorption. The adsorption of FAD on the Ru-modified GCE fits a Langmuir adsorption isotherm. The large apparent negative Gibbs energy of adsorption ΔG _ads (−38.2 kJ mol⁻¹) of FAD onto the Ru-modified GCE confirmed a strong chemical adsorption of FAD on the surface. The deposited Ru islands block surface sites for FAD adsorption and the electron-transfer communication between FAD and the electrode surface does not significantly improve with a deposited Ru monolayer.

Keywords:

• flavin adenine dinucleotied (FAD)
• Ru-modified glassy carbon electrode
• adsorptive thermodynamics
• electron-transfer kinetics

Acknowledgements

Grateful acknowledgment is made to the Natural Science and Engineering Research Council of Canada and Quebec Merit Fellowship, and the National Natural Science Foundation of China (No. 40603007) for support of this research. The authors sincerely thank the reviewers for providing valuable comments on the manuscript.