Han Tao,Feng Liu,Chun Ji,Yuangen Wu,Xiao Wang,Qili Shi
Similar to acetylcholinesterase, the activity of plant-derived esterase can also be inhibited by organophosphorus pesticides. Therefore, an electrochemical sensing platform using kidney bean esterase as a new detection enzyme was proposed for the highly sensitive determination of organophosphorus pesticides. Purified kidney bean esterase was obtained by an efficient and economical aqueous two-phase extraction method. Carboxylated graphene/carbon nanotube composites (cCNTs–cGR) and Au nanoparticles were used to provide a biocompatible environment to immobilize kidney bean esterase and also accelerate electron transport between the analyte and the electrode surface. Due to the good synergistic electrocatalytic effects of these nanomaterials, the biosensor exhibited an amplified electrocatalytic response to the oxidation of α-naphthalenol, which makes the sensor more sensitive. Based on the inhibitory effect of trichlorfon on kidney bean esterase activity, high sensitivity and low-cost detection of trichlorfon was achieved. Under optimum conditions, the inhibition of trichlorfon is proportional to its concentration in the range of 5 to 150 ng L−1 and 150 ng L−1 to 700 ng L−1 with an ultra-low detection limit of 3 ng L−1. Moreover, the validity of the prepared biosensor was verified by analyzing several actual agricultural products (cabbage and rice) with satisfactory recoveries ranging from 94.05% to 106.76%, indicating that kidney bean esterase is a promising enzyme source for the analysis of organophosphorus pesticides in food samples.
Chlorpyrifos (CPF) is the most common pesticide entering the food chain and posing a threat to human health. This study presents a new electrochemical biosensor based on molybdenum disulfide nanosheets and nitrogen-doped carbon dot nanocomposite (MoS2@N-CDs) and kidney bean esterase (KdBE), and it is shown to achieve accurate detection of CPF. MoS2@N-CDs were prepared by a facile solvothermal method and characterized by electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Electrochemical characterization confirmed that MoS2@N-CDs facilitated electron transfer and increased the electroactive surface area of the electrode, thereby improved the sensing performance of the electrode. The oxidation peak current of 1-naphthol, which was produced by the hydrolysis of 1-naphthyl acetate catalyzed by KdBE, was adopted as the signal of the sensor. CPF can suppress KdBE activity and consequently cause a decrease in the sensing signal. The experimental results show that the variation of sensing signal is a reliable index to evaluate the CPF level. Under the optimized conditions, the developed enzyme sensor showed superior CPF assay performance with a linear detection range as wide as 0.01–500 μg L−1 and LOD as low as 3.5 × 10−3 μg L−1 (S/N = 3). The inter- and intra-batch RSDs for electrode testing were 4.02% and 2.69%, respectively. Moreover, the developed biosensor also showed good stability and anti-interference. The spiked recoveries of CPF in oilseed rape and cabbage ranged from 98.09% to 106.01% with low relative standard deviation (RSD) (<5.23%), suggesting that the sensor is a promising tool to enable simple, low-cost but highly sensitive large-scale screening of CPF residues in food.
危险品化学品经营许可证（带存储）