Voltammetric algal biosensor for Hg (II) ion improvised with ZnO nanoparticles

Abstract

Chlorella sp. algae whole cells were immobilised on the surface of glassy carbon electrode and platinum electrode for detection of mercury ions. To improve the sensitivity and detection limit, immobilized electrodes were modified with flower shaped ZnO nanoparticles. ZnO nanoparticles formation was confirmed by various techniques such as FTIR, SEM, photo- luminance (PL), EDS and DRS. Various parameters such as algal concentration, response time, substrate concentration, pH of buffer were optimised for better results. Chronoamperometry, cyclic voltammetry (CV), and differential pulse voltammetry (DPV) techniques were performed for the detection of mercury ions at different concentration. The studies were investigated using algal/GC electrode, ZnO modified algal GC electrode, algal/platinum electrode and ZnO modified algal platinum electrode. It was found that incorporation of ZnO nanoparticles have increased the overall performance of biosensor in terms of detection limit, current response and sensitivity. Results were more effective in ZnO/algal/GC biosensor with the sensitivity 5.42µA/M. ZnO modified algal GC electrode could detect Hg(II) ions through upto 10-13 M by chronoamperometry and 10-9 M by DPV. Further, ZnO modified algal platinum electrode could detect Hg(II) ions in concentration range of 10-11 M -10-3 M. Interference study was carried out by interfering ions such as Ag+, Cu2+, Co2+, Ni2+, Cd2+ with Hg(II) ions. It was found that the proposed biosensor could detect Hg(II) ions without any inference with above mentioned ions.