Coulometric and Chronoamperometric Studies on Bisulfite Reduction at a Surfactant/Myoglobin Film on Glassy Carbon Electrode

Abstract

<i>Background</i>. The redox-active protein, myoglobin (Mb), exchanges electrons very slowly with bare electrodes. Just like on a highly oriented pyrolytic graphite (HOPG) bare electrode, electron transfer between myoglobin (Mb) and a bare glassy carbon (GC) electrode was not observed. The myoglobin (Mb) in di-dodecyl dimethyl ammonium bromide (DDAB) film immobilized on glassy carbon electrode surface had a good charge transport, allowing Mb to be used as a redox catalyst for multi-electron transfer reactions. <i>Objective</i>. We report here the myoglobin on a glassy carbon (GC) electrode as a catalyst for the multi-electron reduction of bisulfite in aqueous buffered solutions. <i>Methods</i>. Coulometry and chronoamperometry are used as tools to probe the Mb/DDAB film on GC electrode as an effective electro-catalyst for the multi-electron reduction of bisulfite. <i>Results</i>. Variation in current with time of bisulfite reduction followed first-order reaction kinetics. The heterogeneous electron transfer rate constant of the film and catalytic rate constant for the reduction of bisulfite were determined. <i>Conclusion</i>. The study confirmed that bisulfite was the reactive species and the catalytic reduction reaction at Mb/DDAB film followed the EC’ catalytic mechanism.