Direct electrochemistry of hemoglobin on a room temperature ionic liquid modified electrode and its electrocatalytic activity for the reduction of oxygen

A room temperature ionic liquid (RTIL), 1-ethyl-3-methyl imidazolium tetrafluoroborate ([EMIm][BF4]), was successfully immobilized on the surface of a basal plane graphite (BPG) electrode through silica sol and Nafion film to form a sol/RTIL/Nafion modified electrode. Direct electrochemistry of hemoglobin (Hb), which was adsorbed on the surface of sol/RTIL/Nafion modified electrode, was investigated. The results from cyclic voltammetry (CV) suggested that Hb could be tightly adsorbed on the surface of the electrode. A couple of well-defined and quasi-reversible CV peaks of Hb can be observed in a phosphate buffer solution (pH 7.0). RTIL shows an obvious promotion for the direct electro-transfer between Hb and electrode. Hb adsorbed on electrode surface exhibits an obvious electrocatalytic activity for the reduction of oxygen O2. The reduction peak currents were proportional linearly to the concentration of oxygen in the range 0.14–1.82 μM. A third generation biosensor based on RTIL can be constructed for the determination of O2.