碳纳米管/乙酰胆碱酯酶电化学生物传感快速检测有机磷农药残留

Rapid Determination of Organic Phosphorus Pesticide Residue by a Carbon Nanotube/Acetylcholinesterase Electrochemical Biosensor

摘要:

有机磷属于神经毒物，能够抑制血液和组织中乙酰胆碱酯酶（AChE）的活性。水溶液中的氯化硫代乙酰胆碱（ATCl）在AChE催化下水解形成巯基胆碱（TCl），TCl在电极表面氧化，可以检测到较大的电流信号。有机磷的存在，降低AChE活性的同时，使得催化水解产生的TCl电化学信号减小。鉴于此原理，研究构建了碳纳米管/聚4-(2,5-二噻吩-1-吡咯)苯胺/乙酰胆碱酯酶电化学传感器（AChE/p-DSPAB/FMWNTs），对溶液的有机磷进行定量分析。电极MWNTs修饰量为1.0 μg/cm2， 电极AChE固载量为1.5 U。最佳条件下，以3.0 ng/mL氯化硫代乙胆碱（ATCl）为底物，在5.0 mL 50 mmol/L PBS（pH=7.0）溶液中，采用微分脉冲伏安法进行测定，电位增量0.006 V、脉冲幅度0.05 V、脉冲宽度0.1 V、脉冲间隔0.1 s。传感器对有机磷检测线性范围为3.00 ng/mL~ 90.00 ng/mL，最低检测限为1.00 ng/mL（S/N = 3）。与高效液相色谱法相比，该法具有简便、准确、快速、样品预处理简单等优点。

Abstract:

Organic phosphorus is a type of neurotoxin capable of inhibiting the activity of acetylcholinesterase (AChE) in the blood and tissues. During AChE catalysis, acetylthiolcholine chloride (ATCl) was hydrolyzed to thiol choline (TCl) in aqueous solution, and TCl was oxidized on the surface of the electrode, thus enabling the detection of large current signals. However, both AChE activity and TCl electrochemical signals produced by hydrolysis decreased in the presence of organic phosphorus. Based on this principle, a new biosensor for the quantitative determination of organic phosphorus was constructed by immobilizing functionalized multi-wall carbon nanotubes (FMWCNTs), p-DSPAB, and AChE on the surface of carbon-paste electrodes. The content of MWCNTs was 1.0 μg/cm2 and the AChE load on the modified electrode was 1.5 U. Under optimal conditions, the measurement of organic phosphorus by differential-pulse voltammetry was performed in 5.0 mL of 50 mmol/L PBS (pH 7.0) solution using 3.0 ng/mL ATCl as the substrate. The detection parameters were as follows: pulse increment, 0.006 V; pulse amplitude, 0.05 V; pulse width, 0.1 V; and pulse interval, 0.1 s. According to the change in the response current and the concentration of organic phosphorus, the biosensor offered a linear range of ~3.00–90.00 ng/mL for the detection of organic phosphorus, and the detection limit was 1.00 ng/mL (S/N = 3). Compared with HPLC, this method has the advantages of simplicity, rapidity, sensitivity, and accuracy in the determination of organic phosphorus.