Acetylcholinesterase With Thio-flavin T System Detect Organic Phosphorus

Organophosphate pesticides that are mainly used in agriculture show low environmental persistence but display high acute toxicity. Their presence in water and food poses a potential hazard to human health. In general these compounds inhibit the acetylcholinesterase (AChE, E.C: 3.1.1.7) participating in nerve-impulse transmission. The inhibition mechanism, being very specific, has led to the development of several analytical techniques for the identification and quantification of such pesticides on the basis of the inhibition of acetylcholinesterase. In this paper, based on enzyme inhibition, a new system for fast reagent-less detection of pesticides has been developed, and AChE-Thioflavin T complex was used as the indicator to detect the pesticides. In AChE-Thioflavin T complex, when organophosphate pesticide is added, the peak F_490nm decrease sharply. The results show that the intensity of fluorescence quenching at 490nm (ΔF_490nm) is linear to the organophosphate pesticide concentration C_OSs. The study of detecting demonstrate that static quenching exists in the AChE-Thioflavin T supramolecular complex. Addition of organophosphate pesticide to the AChE-Thioflavin T complex results in a decrease in fluorescence intensity at 490nm due to displacement of the thioflavin T from the acetylcholinesterase.In this paper, the detection limits of 7.87, and 9.23μg/1 for paraoxon and chlorpyrifos, were achieved respectively, which proved that our method was more sensitive than others in China. The detection system has been applied to the determination of paraoxon inspiked vegetable juices, and satisfactory recovery values were achieved.In this paper, sol-gel based membrane with AChE-Thioflavin T complex as the biorecognition element has been development for the determination of pesticides. The analytical performance including reversibility, reproducibility, stability and selectivity have been evaluated, and can be applied for the direct determination in water samples with satisfactory recoveries.