Abstract
In this paper, the performance of a zinc oxide (ZnO) nanorod-based enzymatic glucose sensor was enhanced with silver (Ag)-doped ZnO (ZnO-Ag) nanorods. The effect of the doped Ag on the surface morphologies, wettability, and electron transfer capability of the ZnO-Ag nanorods, as well as the catalytic character of glucose oxidase (GOx) and the performance of the glucose sensor was investigated. The results indicate that the doped Ag slightly weakens the surface roughness and hydrophilicity of the ZnO-Ag nanorods, but remarkably increases their electron transfer ability and enhances the catalytic character of GOx. Consequently, the combined effects of the above influencing factors lead to a notable improvement of the performance of the glucose sensor, that is, the sensitivity increases and the detection limit decreases. The optimal amount of the doped Ag is determined to be 2 mM, and the corresponding glucose sensor exhibits a sensitivity of 3.85 μA/(mM·cm2), detection limit of 1.5 μM, linear range of 1.5 × 10−3–6.5 mM, and Michaelis-Menten constant of 3.87 mM. Moreover, the glucose sensor shows excellent selectivity to urea, ascorbic acid, and uric acid, in addition to displaying good storage stability. These results demonstrate that ZnO-Ag nanorods are promising matrix materials for the construction of other enzymatic biosensors.
Highlights
Electrochemical enzymatic glucose sensors are of great importance in clinical diagnosis, biological analysis, food processing, and environmental monitoring domains [1,2]
The larger sensitivities and lower detection limits of the Nafion/glucose oxidase (GOx)/zinc oxide (ZnO)-Ag/indium tin oxide (ITO) glucose sensors are mainly ascribed to the fast electron transfer rate of the ZnO-Ag nanorods as well as the better catalytic character of GOx
All of the results suggest that the Nafion/GOx/ZnO-Ag-2/ITO
Summary
Electrochemical enzymatic glucose sensors are of great importance in clinical diagnosis, biological analysis, food processing, and environmental monitoring domains [1,2] Owing to their large surface-to-volume ratio, excellent electron transfer ability, stable chemical property, and good biocompatibility [3,4], different ZnO nanostructures are introduced on the working electrode of a glucose sensor to enlarge the surface area and increase the amount of immobilized GOx. Among them, one-dimensional ZnO nanostructures such as nanorods, nanotubes, nanocombs, and nanodisks, etc. Fidal doped Al in ZnO thin films, and proved that doping with Al increases the carrier concentration of the ZnO thin film as well as the sensitivity of the glucose sensor [17] These nanoparticles enhance the catalytic character of the glucose sensors, and more redox electrons are generated and transferred from the redox active centers of GOx to the ZnO surface.
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