New ZnO nanostructures as non-enzymatic glucose biosensors

Abstract

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 to4 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=7) 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.

Keywords: Amino acid; Glucose; Nanobiosensor; Non-enzymatic; Solvothermal; Zinc oxide.