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[Environmental Chemistry for a Sustainable World] Nanosensors for Environmental Applications Volume 43 || Development of Optical Sensor Strips for Point-of-Care Testing for Pesticide
摘要： Disposable or point-of-care sensors are a promising tool for low-cost and rapid sensing of analytes including pesticides. They find important applications in pesticide-contaminated food, agro-products, and water quality monitoring. This chapter highlights the implication and significance of pesticide residue identification in foodstuffs and overviews the most frequently engaged analytical techniques, and finally their benefits and limitations are discussed. Disposable strip-based biosensors have their intrinsic advantages and some disadvantages, but their cost-effectiveness and portability have turned them as a potential possibility for point-of-care (POC) testing of various pesticides. The fabrication of robust, low-cost, reliable, and sensitive sensors with the aid of both simple naked eye-based and portable readout-based detectors is the driving factor in this sensor’s technology area. The pending limitations can be overcome by adapting new specific recognition elements and better signal generative particles or systems. The integration of these devices with card readers or smartphones can make them more user-friendly and will provide more accurate quantitative information.
关键词： Organophosphates,Pesticide,Immunoassay,Aptamer,Biosensors,Immunochromatographic assay,Point-of-care,Antibody,Rapid detection,Nanosensors,Gas chromatography
更新于2025-09-23 15:21:01
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Simulated revelation of the adsorption behaviours of acetylcholinesterase on charged self-assembled monolayers
摘要： An acetylcholinesterase (AChE)-based electrochemical biosensor, as a promising alternative to detect organophosphates (OPs) and carbamate pesticides, has gained considerable attention in recent years, due to the advantages of simplicity, rapidity, reliability and low cost. The bio-activity of AChE immobilized on the surface and the direct electron transfer (DET) rate between an enzyme and an electrode directly determined the analytical performances of the AChE-based biosensor, and experimental studies have shown that the charged surfaces have a strong impact on the detectability of the AChE-based biosensor. Therefore, it is very important to reveal the behaviour of AChE in bulk solution and on charged surfaces at the molecular level. In this work, the adsorption orientation and conformation of AChE from Torpedo californica (TcAChE) on oppositely charged self-assembled monolayers (SAMs), COOH-SAM and NH2-SAM with different surface charge densities, were investigated by parallel tempering Monte Carlo (PTMC) and all-atom molecular dynamics simulations (AAMD). Simulation results show that TcAChE could spontaneously and stably adsorb on two oppositely charged surfaces by the synergy of an electric dipole and charged residue patch, and opposite orientations were observed. The active-site gorge of TcAChE is oriented toward the surface with the “end-on” orientation and the active sites are close to the surface when it is adsorbed on the positively charged surface and the tunnel cost for the substrate is lower than that on the negatively charged surface and in bulk solution, while for TcAChE adsorbed on the negatively charged surface, the active site of TcAChE is far away from the surface and the active-site gorge is oriented toward the solution with a “back-on” orientation. It suggests that the positively charged surface could provide a better microenvironment for the efficient bio-catalytic reaction and quick DET between TcAChE and the electrode surface. Moreover, the RMSD, RMSF, dipole moment, gyration radius, eccentricity and superimposed structures show that only a slight conformational change occurred on the relatively flexible structure of TcAChE during simulations, and the native conformation is well preserved after adsorption. This work helps us better comprehend the adsorption mechanism of TcAChE on charged surfaces and might provide some guidelines for the development of new TcAChE-based amperometric biosensors for the detection of organophosphorus pesticides.
关键词： electrochemical biosensor,carbamate pesticides,molecular dynamics simulations,conformation,organophosphates,acetylcholinesterase,self-assembled monolayers,adsorption orientation
更新于2025-09-16 10:30:52