Acetylcholinesterase (AChE)-mediated immobilization of silver nanoparticles for the detection of organophosphorus pesticides

Abstract

In this work, we report an enzyme-mediated biosensor with the immobilization of silver nanoparticles (AgNPs) for the detection of organophosphorus (OP) pesticides. Acetylcholinesterase (AChE) catalyzes the hydrolysis of acetylthiocholine into thiocholine, which has a thiol molecule that inhibits the growth of AgNPs. The developed method is based on the inhibition of the enzyme by malathion or trichlorfon, which blocks the generation of thiocholine and leads to the growth of AgNPs during immobilization. The efficiency of enzyme activity was determined during the addition of OP pesticides, which can be correlated to the increase in intensity of the AgNP peak at 420 nm. The increase in intensity of AgNPs was dependent on the concentrations of OPs, and thus, this method allowed low-level detection of 0.455 nM and 5.46 nM for malathion and trichlorfon, respectively, by UV-visible spectroscopy. Further, the proposed detection method was successfully utilized for the detection of OP pesticides in different spiked real samples.