HRP modified pulse laser ablated ZnO nanostructure for H2O2 sensing

Abstract

Biosensor for the detection of hydrogen peroxide (H2O2) has been prepared by immobilizing horseradish peroxidase (HRP) enzyme using physical adsorption technique on zinc oxide (ZnO) nanostructures. The (002) oriented ZnO nanostructures as confirmed by X-ray diffraction, were successfully grown on indium tin oxide (ITO) coated glass substrate by pulsed laser ablation (PLA) without using any catalyst. The Nafion solution was added onto HRP/ ZnO/ ITO bio-electrode to form a tight membrane on the surface before carrying out bio-sensing measurements by electrochemical analyzer. The electrochemical studies reveal that the prepared bio-electrode HRP/ZnO/ITO is highly sensitive to the detection of H2O2 over a wide range of concentration with a linear range from 2.5 μM to 100 μM with the limit of detection 0.2 μM and sensitivity of 0.034 µA/ µM cm2. The higher sensitivity attributed to larger surface area of ZnO nanostructure for effective loading of HRP besides its high electron communication capability. A relatively low value of the enzyme’s kinetic parameter (Michaelis-Menten constant, Km) of 0.166 μM indicates enhanced enzyme affinity of HRP to H2O2. The reported biosensor may be useful for various applications in bio-sensing, clinical, food and beverage industry.