Immobilization of horseradish peroxidase on zinc oxide nanorods grown directly on electrodes for hydrogen peroxide sensing

An amperometric biosensor for hydrogen peroxide detection was developed by immobilization of horseradish peroxidase on zinc oxide nanorods directly grown on the electrode. The ZnO nanorods were fabricated by electrodepositing ZnO nanoseeds on indium tin oxide glass followed by a hydrothermal growth process. The ZnO nanorods were used to increase the specific surface area for carrying horseradish peroxidase and to build direct electron transfer channels to the electrode. The structure of the ZnO nanorods on indium tin oxide was studied by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and the electrochemical behaviors were carefully examined. The result showed that the biosensor responds well to hydrogen peroxide in a wide range of concentration. The linear range is from 0.5 to 9.0 mM with a limit of detection (S/N = 3) of 0.3 mM, and the response time is about 7 s, which indicates that ZnO nanorods are promising supporting materials to build direct electron transfer biosensors.