Gold nanoprobe for inhibition and reactivation of acetylcholinesterase: An application to detection of organophosphorus pesticides

Abstract

The organophosphorus compound (OP) induced inhibition of acetylcholinesterase (AChE) and their reactivation has been monitored using gold nanoprobe. The method is based on the colour change and red shift of localized surface plasmon resonance (LSPR) absorption band of AuNPs in UV–vis region after the addition of acetylthiocholine in presence of AChE. The aggregation of AuNP is induced by the thiocholine (TCh) through Au-S binding and electrostatic force of interactions. The inhibitory attack of OPs at the active serine site of the AChE leads to the decrease in formation of TCh molecule, which consequently, prevents the aggregation of the AuNPs. Conversely, the red shift of LSPR has been regained upon the reactivation of OP inhibited AChE by oximates (2-PyOx−, 4-C12PyOx−) and salicylhydroxamate (SHA). The inhibition protocols of the AChE have been used for detection of OP pesticides. The linear range for determination of OPs was found in range of 0.30–17.30 ng mL−1 with their limit of detection being 0.13 ng mL−1, 0.37 ng mL−1, 0.42 ng mL−1 and 0.20 ng mL−1 for paraoxon, parathion, fenitrothion and diazinon, respectively. The proposed method was found to be simple, sensitive and cost effective for the determination of OPs in real water samples.