基于复合纳米微粒修饰和磁性分离富集的一次性有机磷农药酶传感器

在Fe3O4/Au微粒上固定乙酰胆碱酯酶(AChE),制得磁性复合粒子Fe3O4/Au/AChE。通过磁力将其吸附于涂覆了碳纳米管(CNTs)/纳米ZrO2/普鲁士蓝(PB)/Nafion(Nf)复合膜的丝网印刷碳电极(SPCEs)表面,制得一次性有机磷农药(OPs)酶传感器。采用扫描电镜(SEM)、X射线荧光光谱(XRFS)表征传感器的制备过程,采用循环伏安法(CV)和示差脉冲伏安法(DPV)研究了传感器的电化学性质。利用OPs对AChE的抑制作用,以硫代乙酰胆碱(ATCh)为底物,对乐果进行了检测。在pH=7.5的0.1 mol/L硝酸钾溶液中,乐果浓度的对数与酶电极的抑制率(A)在1.0×10-6~1.0×10-2 mg/L间呈良好的线性关系,检测限为5.6×10-7 mg/L,用于实际样品白菜检测时的添加回收率在88% ~105%之间,与气相色谱法(GC)所得结果一致。该传感器采用复合纳米粒子修饰电极表面,具有较高的比表面活性,响应迅速,检测限低;ZrO2可特异性地富集样品中的OPs,磁性纳米颗粒包被AChE可实现磁场分离和电极表面更新,且具有高灵敏度、低样品量、一次使用可抛弃、便携式等特点,可用于蔬菜等农产品中痕量OPs的快速、简便、准确检测。

A Disposable Organophosphorus Pesticides Enzyme Biosensor Based on Composite Nano-particles and Magnetic Separation with Enrichment Modified Screen-printed Carbon Electrodes

The composite magnetic particulate composed of Fe₃O₄/Au/acetylcholinesterase (AChE) was synthesized and was absorbed on the surface of screen-printed carbon electrodes (SPCEs) coated with carbon nanotubes(CNTs)/nano-ZrO₂/prussian blue (PB)/nafion (Nf)-membrane through magnet.A disposable organophosphorus pesticides (OPs) enzyme biosensor was developed for the determination of dimethoate.Different technologies were employed to study the construction process and electrochemical properties of the biosensor.In pH 7.5 0.1 mol/L KNO₃ solution,the rate of inhibition (A) of the AChE by OPs was related linearly to the concentration of dimethoate in the range from 1.0×10^-6 to 1.0×10^-2 mg/L with a detection limit of 5.6×10^-7 mg/L.The recovery was 88%-105% for chinese cabbage.The results of the analytical method were compaprable with that of gas chromatography method.The proposed biosensor has high surface activity due to the modification with composite nano-particles,rapid response,specific strong adsorption to OPs and was easily renew by removal of the magnet.It showed the merits of high sensitivity, disposabledesign,low consume of sample and portablity compared with other enzyme biosensors.This convenient,fast and sensitive voltammetric test method is suitable for the fast anlysis of OPs.