Indirect determination of mercury ion by inhibition of a glucose biosensor based on ZnO nanorods
By: Chey, Chan Oeurn; Ibupoto, Zafar Hussain; Khun, Kimleang; Nur, Omer; Willander, Magnus
A potentiometric glucose biosensor based on immobilization of glucose oxidase (GOD) on ZnO nanorods (ZnO-NRs) has been developed for the indirect detn. of environmentalmercury ions. The ZnO-NRs were grown on a gold coated glass substrate by using the low temp. aq. chem. growth (ACG) approach. Glucose oxidase in conjunction with a chitosan membrane and a glutaraldehyde (GA) were immobilized on the surface of the ZnO-NRs using a simple phys. adsorption method and then used as a potentiometric working electrode. The potential response of the biosensor between the working electrode and an Ag/AgCl ref. electrode was measured in a 1mM phosphate buffer soln. (PBS). The detection limit of the mercury ion sensor was found to be 0.5 nM. The exptl. results provide two linear ranges of the inhibition from 0.5 × 10-6 mM to 0.5 × 10-4mM and from 0.5 × 10-4 mM to 20 mM of mercury ion for fixed 1 mM of glucose concn. in the soln. The linear range of the inhibition from 10-3 mM to 6 mM of mercury ion was also acquired for a fixed 10 mM of glucose concn. The working electrode can be reactivated by more than 70% after inhibition by simply dipping the used electrode in a 10 mM PBS soln. for 7 min. The electrodes retained their original enzyme activity by about 90% for more than three weeks. The response to mercury ions was highly sensitive, selective, stable, reproducible and interference resistant and exhibits a fast response time. The developed glucose biosensor has a great potential for detection ofmercury with several advantages such as being inexpensive, requiring min. hardware and being suitable for unskilled users.