A sensitive acetylcholinesterase biosensor based on gold nanorods modified electrode for detection of organophosphate pesticide

Palladium-copper nanowires-based biosensor for the ultrasensitive detection of organophosphate pesticides

A highly sensitive acetylcholinesterase (AChE) electrochemical biosensor for the quantitative determination of organophosphate pesticides (OPs) in vegetables and fruits based on palladium-copper nanowires (Pd-Cu NWs) was reported. AChE immobilized on the modified electrode could catalyze hydrolysis of acetylthiocholine chloride (ATCl), generating an irreversible oxidation peak. When exposed to the OPs, the activity of the AChE was inhibited and the current significantly decreased. The detection mechanism is based on the inhibition of AChE. The Pd-Cu NWs not only provide a large active surface area (0.268 ± 0.01) cm² for the immobilization of AChE, which was approximately 3.8 times higher than the bare glass carbon electrode, but also exhibit excellent electro-catalytic activity and remarkable electron mobility. The biosensor modified with Pd-Cu NWs displayed a good affinity to ATCl and catalyzed hydrolysis of ATCl, with a low Michaelis-Menten constant (K_M) of 50.56 μM. Under optimized conditions, the AChE-Cs/Pd-Cu NWs/GCE biosensor detected malathion with wide linear ranges of 5-1000 ppt and 500-3000 ppb, and the low detection limit was 1.5 ppt (4.5 pM). In addition, the OPs biosensor has been applied to the analysis of malathion in commercial vegetable and fruit samples, with excellent recoveries in the range of 98.5%-113.5%. This work provides a simple, sensitive and effective platform for biosensors and exhibits future potential in practical application for the OPs assay.

Novel Cell-Inorganic Hybrid Catalytic Interfaces with Enhanced Enzymatic Activity and Stability for Sensitive Biosensing of Paraoxon

To improve the biosensing performance of organophosphorus hydrolase (OPH), the novel bioinorganic hybrid catalysts were facilely explored by biomineralization and cell surface display technology. During biomineralization, cobalt phosphate crystals were deposited onto the surface of OPH-fused bacteria, and the inorganic crystals at middle of cell collapsed inwardly to form the final spindle morphology because of the lowest energy principle and the mechanics principle. OPH would show the allosteric effect from "inactive" form to "active" form, and the "active" form was "fixed" when OPH was embedded into cobalt phosphate. Therefore, the activity of mineralized OPH-fused cells was greatly enhanced about 3 times in comparison with original OPH-fused cells. Additionally, the stability of the novel hybrid catalysts was also significantly improved. Further, the as-synthesized bioinorganic hybrid catalysts were applied to sensitive paraoxon biosensing, which exhibited lower limit of detection than that of the original counterpart. Thus, this hybrid biocatalytic system would provide a model to develop a wide range of biocatalysts and find a wide range of applications in industrial catalysis, analytical chemistry, and environmental engineering.