An Electrochemical Glucose Sensor Based on Zinc Oxide Nanorods

The fabrication of an electrochemical sensor for glucose detection using hydrothermally grown zinc oxide (ZnO) nanorods is investigated. The working principle is based on the electrochemical reaction taking place between immobilized glucose oxidase adsorbed by the ZnO nanorods, and the electrolyte glucose. The synthesis of ZnO nanorods on indium tin oxide (ITO) coated glass substrate was performed using a hydrothermal sol-gel growth technique. Characterization of the ZnO nanorods was performed by using the absorption, micro-Raman, and scanning electron microscopies, and the X-ray diffraction analysis. Nafion/GOx/ZnO nanorods/ITO-coated glass substrate was used as a working electrode, while the reference electrode was a platinum plate. Amperometric response for clinical range of blood glucose concentration from 0.01-20 mM is measured at +0.8 V. The response time for the tested sensor obtained from the amperometric response curve is estimated to be less than 3 s. The analyzed sensitivity of 1151 µA/cm 2 mM-1 and the lower detection limit of 0.089 mM for the sensor were estimated from the glucose linear concentration range of 0.01 – 1.6 mM. Electrochemical characterization of the sensor was performed using the cyclic voltammetry method for a voltage range of-0.8-0.8 V at a sweep rate of 100 mV/s. Long term stability of the investigated sensor is discussed based on the study of nafion membrane scanning electron microscopy results, performed before and after the amperometric titration.

An electrochemical glucose sensor based on zinc oxide (ZnO) nanorods is fabricated, characterized and tested. The ZnO nanorods are synthesized on indium titanium oxide (ITO) coated glass substrate, using the hydrothermal sol-gel technique. The working principle of the sensor under investigation is based on the electrochemical reaction taking place between cathode and anode, in the presence of an electrolyte. A platinum plate, used as the cathode and Nafion/Glucose Oxidase/ZnO nanorods/ITO-coated glass substrate used as anode, is immersed in pH 7.0 phosphate buffer solution electrolyte to test for the presence of glucose. Several amperometric tests are performed on the fabricated sensor to determine the esponse time, sensitivity and limit of detection of the sensor. A fast response time less than 3 s with a high sensitivity of 1.151 mA cm-2mM-1 and low limit of detection of 0.089 mM is reported. The glucose sensor is characterized using the cyclic voltammetry method in the range from -0.8 – 0.8 V with a voltage scan rate of 100 mV/s.

Chemosensors, 2017

The influence of the as-grown zinc oxide nanorods (ZnO NRs) on the fabricated electrochemical sensor for in vitro glucose monitoring were investigated. A direct growth of ZnO NRs was performed on the Si/SiO 2 /Au electrode, using hydrothermal and sol-gel techniques at low temperatures. The structure, consisting of a Si/SiO 2 /Au/GO x /Nafion membrane, was considered as a baseline, and it was tested under several applied potential 0.1-0.8 V. The immobilized working electrode, with GO x and a nafion membrane, was characterized amperometrically using a source meter Keithely 2410, and an electrochemical impedance Gamry potentiostat. The sensor exhibited the following: a high sensitivity of ~0.468 mA/cm 2 mM, a low detection limit in the order of 166.6 µM, and a fast and sharp response time of around 2 s. The highest sensitivity and the lowest limit of detection were obtained at 0.4 volt, after the growth of ZnO NRs. The highest net sensitivity was obtained after subtracting the sensitivity of the baseline, and it was in the order of 0.315 mA/cm 2 •mM. The device was tested with a range of glucose concentrations from 1-10 mM, showing a linear line from 3-8 mM, and the device was saturated after exceeding high concentrations of glucose. Such devices can be used for in vitro glucose monitoring, since glucose changes can be accurately detected.

MRS Advances, 2016

Glucose sensor based on ITO/ZnO NRs/GOx/nafion is fabricated and tested under different glucose concentrations. Hydrothermal growth method along with sol-gel technique is used to grow high quality ZnO nanorods that have well-alignment and high density with an acceptable aspect ratio. The as-grown of ZnO nanorods are used to fabricate a working electrode that can be used for glucose detection in blood after a modification process with GOx and nafion membrane. Annealing at 110 °C helped in improves the crystallinity of the seed layer and as a result, a high density and well alignment as-grown ZnO nanorods were obtained. High sensitivity and short response time were obtained from the fabricated device with an acceptable lower limit of detection.

The fast and accurate determination of glucose has intense applications in the field of biology and medicine as glucose concentration is a crucial indicator in many diseases, such as diabetes. Because of this reason the most widespread biosensors today are the glucose biosensors [1]. Keeping this in view, the objective of this experiment was: • To fabricate a highly sensitive Glucose Biosensor by using Zinc oxide Nanostructures. • To observe the performance of this biosensor through Cyclic Voltammetry and Amperometric techniques.

Sensors and Actuators B: Chemical, 2014

Hydrothermally grown ZnO nanorods were used for enzyme immobilization in glucose sensors. In particular, the surface area of the ZnO nanorods was tailored by the use of a seed layer and/or by changing the concentration of the precursors. The glucose sensing capability was found to be strongly associated with the surface area of the nanorods. The results clearly demonstrated that hydrothermally grown ZnO nanorods be successfully applied to the electrode system for the detection of glucose. In addition, the growth conditions also need to be carefully optimized in order to grow ZnO nanorods that are as slim and long as possible in order to maximize the surface area.

Biosensors & Bioelectronics, 2010

In this article, we report a functionalised ZnO-nanorod-based selective electrochemical sensor for intracellular glucose. To adjust the sensor for intracellular glucose measurements, we grew hexagonal ZnO nanorods on the tip of a silver-covered borosilicate glass capillary (0.7 μm diameter) and coated them with the enzyme glucose oxidase. The enzyme-coated ZnO nanorods exhibited a glucose-dependent electrochemical potential difference versus an Ag/AgCl reference microelectrode. The potential difference was linear over the concentration range of interest (0.5–1000 μM). The measured glucose concentration in human adipocytes or frog oocytes using our ZnO-nanorod sensor was consistent with values of glucose concentration reported in the literature; furthermore, the sensor was able to show that insulin increased the intracellular glucose concentration. This nanoelectrode device demonstrates a simple technique to measure intracellular glucose concentration.

Journal of Nanoscience and Nanotechnology, 2008

Well-crystallized zinc oxide nanonails were grown in a high density by thermal evaporation process and were used as supporting matrixes for glucose oxidase (GOx) immobilization to construct efficient glucose biosensor. The GOx attached to the surfaces of ZnO nanonails had more spatial freedom in its orientation, which facilitated the direct electron transfer between the active sites of immobilized GOx and electrode surface. The fabricated biosensor showed a high sensitivity of 24.613 μA cm–2 mM–1 with a response time less than 10 s. Moreover, it shows a linear range from 0.1 to 7.1 mM with a correlation coefficient of R = 0.9937 and detection limit of 5 μM.

Biosensors and Bioelectronics, 2015

In a new approach, shape controlled synthesis of zinc oxide nanostructures were carried out using a solvothermal route assisted amino acids such as L-Lysine (lysine), L-Cysteine (cysteine) and L-Arginine (arginine) as bifunctional species with (or without) urea or oxalic acid as additives which affect the pH of the reaction. Rod, powder, particle, cube, rock candy-like, sheet, sphere, brain-like, groundnut-like and pussy willow-like morphologies were obtained through the synthetic route. Particle sizes varied from 25 nm to 4 μm. To test the application, nine ZnO nanostructures, formulated by multi-walled carbon nanotube (MWCNT) on glassy carbon electrode (GCE) were applied as new nanobiosensors for detecting glucose in a simple and inexpensive way without using any glucose oxidase or nafion. Glucose sensing accomplished in a phosphate buffer solution (PBS, pH ¼7) for ZnO/MWCNT/GCE samples. Results showed that in this non-enzymatic biosensor system, spherical ZnO obtained from zinc acetate/cycteine/oxalic acid synthetic route has the highest sensitivity of 64.29 μA/cm 2 mM with repeatable results. For the mentioned sensor, no interference observed in the presence of dopamine, uric acid and fructose.