L-Ascorbic Acid Biosensor Based on Immobilized Enzyme on ZnO Nanorods.

Z H Ib Upoto,K Khun,Syed M Usman Ali,M Willander

doi:10.4172/2155-6210.1000110

Abstract

In this present research, we have grown the well aligned, perpendicular to the substrate and highly dense ZnO nanorods on the gold coated substrate by using the hydrothermal growth method. The ZnO nanorods were functionalized by immobilizing the ascorbate oxidase enzyme with cross linking molecule 3-glycidoxypropy1trimethoxysilane (GPTS).The electrochemical measurements were carried out through using potentiometric technique, we observed that the output response exhibited by the biosensor to the wide linear dynamic range concentration of L-ascorbic acid from 1×10 -6 to 5×10 -2 M with good sensitivity of 32 mV/decade. Moreover the biosensor showed excellent fast response time less than 10 seconds, better selectivity, repeatability, reproducibility and no significant interference to the common interfering ions such as potassium K +1 , sodium ions Na +1 , calcium ions Ca +2 , glucose, fructose, and zinc ions Zn +2 etc. except slight interference with copper Cu +2 ions.

Highlights

The vitamin C which is called L-ascorbic acid with chemical name is vital for the human health due to its determined excellent properties [1,2,3]
Ellipsometric analysis: The purpose of using this technique was to know about the thickness of different layers produced on the gold coated substrates. During this measurement we found that the thickness of grown ZnO nanorods onto the gold coated substrate was about 99.10±2.88 nm and it was observed that the grown ZnO nanorods are almost uniform throughout the substrates
When the sensor electrodes were exposed to the test solution the immobilized ascorbate oxidase on ZnO nanorods makes more catalytic enhancement to oxidize the l-ascorbic acid into dehydro-ascorbic acid (DAA),after that hydrogen ions and two electrons are produced into the analyte solution resulting to produce a stable response at the output