Biosensor for Organophosphorus Pesticides Detection by the Fabrication of ZnO Nanoparticles

Abstract

Flower shaped ZnO nanoparticles (NPs) were synthesized by sol gel process using Zn(NO3)2 as precursor and were used in the fabrication of ISFET biosensor for detection of organophosphorus pesticides (OPs). In this work, whole cell algae Chlorella sp. having surface bound alkaline phosphatase (AP) was exploited for study. Three experimental sets were done which include (i) direct interaction of enzyme and pesticide without immobilizing algae (ii) immobilizing algae on surface of ISFET Ta2O5 electrode (iii) modifying electrode surface by ZnO NPs incorporated –algae. The basis of detection states that AP dephosphorylates substrate 2-Phospho-L-ascorbic acid trisodium (PAA) to ascorbic acid (AA), which was detected by ISFET transducer. OPs inhibits the activity of enzyme AP, which gives current change on the change of the pH of the solution. The extent of inhibition gives the concentration of OP present. OPs studied were chloropyrifos, triazophos and malathion. Among these, chlorpyrifos showed highest AP enzyme inhibition upto 10 -9 M and malathion was the least. It was found that among three methods studied ZnO modified electrode showed better results.