Electrochemistry of hemoglobin on a gold colloid-1,4-benzenedimethanethiol modified electrode and electrocatalyte detection of hydrogen peroxide

Hemoglobin (Hb) was successfully immobilized on gold nanoparticles (GNP) associated with a 1,4-benzenedimethanethiol (BDT) monolayer on a gold electrode surface and was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Direct electron transfer (DET) between Hb and the modified electrode was achieved without the aid of any electron mediator. GNP can greatly promote. the redox of Hb, on which a pair of obvious CV peaks for Hb Fe(III)/Fe(III) redox couple were obtained in pH 6.2 phosphate buffer solution (PBS). In pH 6.2 PBS, the formal potential (E-o,E-) of Hb was -0.180 V (versus SCE), and the electron transfer rate constant was 5.2 s(-1). The formal potential of Hb on gold colloidal modified electrode shifts linearly with pH with a slope of -55.5 mV/pH at 20degreesC, showing that the electron transfer is accompanied by single proton transportation. The high efficiency of the Hb/GNP/BDT modified gold electrode toward the catalytic electroreduction of hydrogen peroxide has been observed. The immobilized Hb gave an excellent electrocatalytic response to H2O2. Potential application of Hb/GNP/BDT modified gold electrode as biosensors to monitor H2O2 is proposed.