Hydrothermal Growth of Zinc Oxide Nanorods and Glucose-Sensor Application

High-quality zinc oxide nanorods were grown on various substrates using zinc nitrate (Zn(NO3)2) and hexamethylenetetramine ((CH2)6N4). The substrates greatly affect the hydrothermal growth of ZnO nanorods. Making the best use the substrate effect, we engineered substrates to make a single nanorod in each hole of 100 nm × 100 nm in the array of the holes on the photoresist-patterned substrate. It is also interesting to note that high-quality ZnO nanorods grown on GaN substrates by the hydrothermal growth technique have demonstrated the potential application as a glucose sensor without oxidase for the first time. The photoluminescence in the UV wavelength range was quenched by immobilizing glucose on the ZnO surface. The peak intensity decreased increased with the increased glucose concentrations. A good linearity and high sensitivity were obtained for the glucose concentrations of 0.5-30 mM in the calibration curve. The calibration curve was not influenced by the presence of bovin serum albumin (BSA), ascorbic acid (AA) and uric acid (UA), which are also included in human blood and could cause interference in estimating glucose concentrations in human blood. The PL quenching was attributed to the H2O2 molecules, which were produced by the photo-oxidation of glucose during exposure to UV light. The PL-quenching glucose sensor made of ZnO nanorods has been evaluated for the first time by estimating the glucose concentrations in the human serum samples which include those of diabetes, and a good correlation was obtained between the concentrations by the PL quenching and the clinical data provided by a local hospital.