Indium tin oxide electrode modified by a SH+ ion implantation technique for direct electrocatalytic sensing of hydrogen peroxide

Abstract

A novel method was developed by immobilizing hemoglobin (Hb) on indium tin oxide (ITO) electrode modified by a SH⁺ ion implantation technique to fabricate a hydrogen peroxide sensor. Hb was pipetted onto the cleaned surface of the SH/ITO electrode. Then the 0.5% Nafion was spread onto the surface of Hb. The resulting electrode was characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), electrochemical impedance spectroscopy (EIS) and ultraviolet-visible (UV-vis) spectroscopy. The immobilized Hb displayed an excellent electrocatalytical response to the reduction of hydrogen peroxide. The performance and factors influencing the resulting biosensor were studied in detail. The resulting biosensor exhibited a fast amperometric response (within 5 s) to H₂O₂. The modified electrode displayed a sensitivity of 0.62 μA μM⁻¹ and a detection limit of 0.1 μM estimated at a signal-to-noise ratio of 3. Furthermore, the biosensor exhibited high sensitivity, good reproducibility, and long-term stability.