Paper-based acetylcholinesterase inhibition assay combining a wet system for organophosphate and carbamate pesticides detection

摘要

A dramatic increase in pesticide usage in agriculture highlights the need for on-site monitoring for public healthand safety. Here, a paper-based sensor combined with a wet system was developed for the simple and rapidscreening of organophosphate (OP) and carbamate (CM) pesticides based on the inhibition of acetylcholinesterase(AChE). The paper-based sensor was designed as a foldable device consisting of a cover and detection sheetspre-prepared with indoxyl acetate and AChE, respectively. The paper-based sensor requires only the incubationof a sample on the test zone for 10 minutes, followed by closing of the foldable sheet to initiate the enzymaticreaction. Importantly, the buffer loading hole was additionally designed on the cover sheet to facilitate the interactionof the coated substrate and the immobilized enzyme. This subsequently facilitates the mixing of indoxylacetate with AChE, resulting in the improved analytical performance of the sensor. The absence or decrease inblue color produced by the AChE hydrolysis of indoxyl acetate can be observed in the presence of OPs andCMs. Under optimized conditions and using image analysis, the limit of detection (LOD) of carbofuran, dichlorvos,carbaryl, paraoxon, and pirimicarb are 0.003, 0.3, 0.5, 0.6, and 0.6 ppm, respectively. The assay could beapplied to determine OP and CM residues in spiked food samples. Visual interpretation of the color signal wasclearly observed at the concentration of 5 mg/kg. Furthermore, a self-contained sample pre-concentration approachgreatly enhanced the detection sensitivity. The paper-based device developed here is low-cost, requiresminimal reagents and is easy to handle. As such, it would be practically useful for pesticide screening by nonprofessionalend-users.