Colorimetric Detection of Organophosphate Pesticides Based on Acetylcholinesterase and Cysteamine Capped Gold Nanoparticles as Nanozyme

Abstract

Organophosphates (OPs) are neurotoxic agents also used as pesticides that can permanently block the active site of the acetylcholinesterase (AChE). A robust and sensitive detection system of OPs utilising the enzyme mimic potential of the cysteamine capped gold nanoparticles (C-AuNPs) was developed. The detection assay was performed by stepwise addition of AChE, parathion ethyl (PE)-a candidate OP, acetylcholine chloride (ACh), C-AuNPs, and 3, 3′, 5, 5′-tetramethylbenzidine (TMB) in the buffer solution. The whole sensing protocol completes in 30–40 min, including both incubations. The Transmission Electron Microscopy (TEM) results indicated that the NPs are spherical and have an average size of 13.24 nm. The monomers of C-AuNPs exhibited intense catalytic activity (nanozyme) for the oxidization of TMB, revealed by the production of instant blue colour and confirmed by a sharp peak at 652 nm. The proposed biosensor’s detection limit and linear ranges were 5.8 ng·mL−1 and 11.6–92.8 ng·mL−1, respectively, for PE. The results strongly advocate that the suggested facile colorimetric biosensor may provide an excellent platform for on-site monitoring of OPs.

Recent advances in colorimetric sensors based on nanozymes with peroxidase-like activity

“…2). Additionally, some materials, such as quantum dots (QDs), 68 β-cyclodextrin (β-CD), 69 polyoxometalates (POMs), 70 polyvinyl alcohol, 71 hydrogel, 72 cysteamine 73 and tannic acid 74 combined with Au NPs showed higher cata-Fig. 1 Schematic diagram of the nanozyme aptasensor prepared by adapting Au NPs to norovirus aptamer.…”

“…2). Additionally, some materials, such as quantum dots (QDs), 68 β-cyclodextrin (β-CD), 69 polyoxometalates (POMs), 70 polyvinyl alcohol, 71 hydrogel, 72 cysteamine 73 and tannic acid 74 combined with Au NPs showed higher catalytic activity under neutral conditions, and were successfully utilized for colorimetric detection of metal ions and small biological molecules.…”

Organophosphate-induced inhibition of acetylcholinesterase, oxidative stress and neuroinflammation

“…The enzyme forms a trigonal intermediate rather than a tetrahedral intermediate, and the tetrahedral intermediate forms a very stable phosphate ester when it breaks down. The phosphorylated enzyme is inactive and cannot hydrolyze the neurotransmitter [11]. Therefore, there would be too little AChE to degrade acetylcholine, leading to too much acetylcholine accumulated in the nervous system, which in turn would cause neurotoxicity.…”

The Selective Detection of Cyantraniliprole Insecticides Using Molecularly Imprinted Polymers Coupled with an Acetylcholinesterase Inhibition‐Based Biosensor

“…applied this strategy coupled with nanomaterials to increase the sensitivity. [26] The detection limit was 5.8 ng mL À 1 . Thiocholine is a by-product of the hydrolysis of acetylthiocholine by acetylcholinesterase.…”

“…Shah et.al . applied this strategy coupled with nanomaterials to increase the sensitivity [26] . The detection limit was 5.8 ng mL −1 .…”