Development of Glutamate Sensor Based on Nickel Oxide Nano Particle

Abstract

L-glutamic acid is one of the 20 standard amino acids used by all organisms. It plays an important role in clinical applications and in food processing and well known as a flavor enhancer commonly found in various foods. The excessive intake of this flavor enhancer can cause toxic effect to the human health. Therefore, development of sensors or biosensors for the determination of glutamate has been of great interest over the past two decades owing to its importance in food and biomedical industries. In this study nickel oxide nanocrystal and nickel oxide hollowsphere have synthesized by using sol-gel and hydrothermal methods. Morphological characterization of nickel oxide particle was carried out using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The crystallite size of nickel oxide prepared by sol-gel method has been found 60 nm. Nickel oxide nanocrystal shows higher selectivity towards glutamate detection compare to nickel oxide hollowsphere. The enzyme-free sensor has been fabricated through modification of glassy carbon using the mixture of nickel oxide nanocrystals and citosan (NiO/GCE). Cyclic voltammetry (CV) and amperometry were used to investigate the electrochemical behavior and catalytic properties of the assembled sensor for glutamate electro-oxidation in alkaline media. It has been found that NiO/GCE showed remarkably enhanced electrocatalytic activity towards glutamate and the electrochemical reaction is diffusion controlled. The sensitivity of NiO/ GCE has been found to be 11 μA/mM/cm2. Under optimal detection conditions, the sensor exhibited linear behavior for glutamate detection in the concentration up to 8 mM with a limit of detection of 272 μM. The interference study of NiO/GCE has been found a significant current response for glutamate compared to the uric acid and ascorbic acid. The stability of NiO/GCE has been studied over a period of one week and found to retain 65% of its original activity towards glutamate detection. Experimental results show that NiO/GCE has significant promise for fabricating cost effective, enzyme-less, sensitive, stable and selective sensor platform.