Direct electron transfer of hemoglobin and myoglobin at the bare glassy carbon electrode in an aqueous BMI.BF4 ionic-liquid mixture.

Direct and remarkably fast electron transfers between a bare glassy carbon electrode and heme proteins (hemoglobin or myoglobin) are obtained by using an aqueous 1-butyl-3-methyl imidazolium tetrafluoroborate (BMI.BF(4)) ionic-liquid mixture as electrolyte. The ionic liquid is observed to play a key role in the achievement of the electron transfer. The experimental data show that the proteins are not strongly adsorbed onto the electrode surface while giving rise to sharp and well-defined redox responses. Such a finding contrasts with most of the reported works found in literature and-beyond the fundamental aspect--it may be of interest in applications where adsorption is critical. Moreover, the electrocatalytic activity of the proteins toward the reduction of oxygen and nitrite in the aqueous BMI.BF(4) mixture is evidenced, showing the potential of this simple approach for bioelectroanalytical devices.