Interaction of flavin adenine dinucleotide (FAD) with a glassy carbon electrode surface.
The interaction of flavin adenine dinucleotide (FAD) with a glassy carbon electrode (GCE) surface was investigated in terms of the FAD adsorption thermodynamics and kinetics, the subsequent electroreduction mechanism, and the corresponding electron-transfer rate. The kinetics of FAD electroreduction at the GCE was found to be an adsorption-controlled process. A set of electroreduction kinetic parameters was calculated: the true number of electrons involved in the FAD reduction, n=1.76, the apparent transfer coefficient, alpha(app)=0.41, and the apparent heterogeneous electron-transfer rate constant, k(app)=1.4 s(-1). The deviation of the number of exchanged electrons from the theoretical value for the complete reduction of FAD to FADH(2) (n=2) indicates that a small portion of FAD goes to a semiquinone state during the redox process. The FAD adsorption was well described by the Langmuir adsorption isotherm. The large negative apparent Gibbs energy of adsorption (DeltaG(ads)=-39.7 +/-0.4 kJ mol(-1)) indicated a highly spontaneous and strong adsorption of FAD on the GCE. The energetics of the adsorption process was found to be independent of the electrode surface charge in the electrochemical double-layer region. The kinetics of FAD adsorption was modeled using a pseudo-first-order kinetic model.
Wei
Haizhen
H
Department of Chemical Engineering, McGill University Montreal, 3610 University Street, Montreal Quebec, H3A 2B2, Canada, (phone: +1 (514) 398-4273; fax: +1 (514) 398-6678).|Current address: School of Materials Science and Engineering, Nanjing University of Technology, Nanjing, 210009, P. R. China.
Omanovic
Sasha
S
Department of Chemical Engineering, McGill University Montreal, 3610 University Street, Montreal Quebec, H3A 2B2, Canada, (phone: +1 (514) 398-4273; fax: +1 (514) 398-6678).
D000327:Adsorption; D002244:Carbon / Q000737:chemistry*; D004563:Electrochemistry; D004566:Electrodes; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry*; D005898:Glass / Q000737:chemistry; D007700:Kinetics; D015394:Molecular Structure; D010084:Oxidation-Reduction; D013499:Surface Properties; D013816:Thermodynamics
D005182:Flavin-Adenine Dinucleotide; D002244:Carbon