农药残留检测用新型碳纳米管固载酶生物传感器的制备及其电学传感性能分析

采用滴涂法、自组装法及化学键合法制备了基于碳纳米管(CNTs)修饰的乙酰胆碱酯酶(AChE)生物传感器,采用循环伏安法(CV)、计时电流法(CA)、交流阻抗法(EIS)和扫描电镜(SEM)对生物传感器的电化学性能和表面形貌进行表征,通过采用该生物传感器对异丙威(氨基甲酸酯类农药)进行分析的结果,考察了其检测性能,研究了各生物传感器的动力学性质及电化学行为,并构建了新型固载酶生物传感器的等效电路模型。结果表明:各生物传感器表观表面积比裸电极显著提高,其电子传递速率遵循以下顺序逐渐降低:乙酰胆碱酯酶(AChE)/壳聚糖(CS)/功能化碳纳米管(F-CNTs/GCE)生物传感器AChE/F-CNTs/GCE生物传感器CS/双醛纤维素固载酶(DAC-AChE)/F-CNTs/GCE生物传感器,各传感器表观电子传递速率常数分别为:k s AChE/CS/F-CNTs/GCE=0.24 s-1,k s AChE/F-CNTs/GCE=0.23 s-1和k s CS/DAC-AChE/F-CNTs/GCE=0.22 s-1。获得生物传感器电学阻抗谱等效电路模型为R1(CPE1(R2(CPE2(R3)))),计算得到等效电路模型中各具体元件参数,证明该有效电路能有效模拟生物传感器检测异丙威的传感机理。该研究结果可为农药残留检测用生物传感器分析机理研究提供有益参考。

Preparation of new carbon nanotubes immobilized enzyme biosensor for pesticide residue detection and analysis of its electrochemical sensing properties

The acetyl cholinesterase biosensors modified by carbon nanotubes were prepared by drop coating, self-assembly and chemical bonding methods. The electrochemical sensing properties and morphology of biosensor was characterized through cyclic voltammetry (CV), chronoamperometry (CA), electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM). The performance of the biosensor analyzing typical carbamate pesticide isoprocarb was investigated. The kinetic properties and electrochemical behavior of each biosensor was researched. A new equivalent circuit model on immobilized enzyme biosensor was built based on these findings. The results showed that, compared to bare electrode, the apparent surface areas of each biosensor was substantial increased, and the electron transfer rate of each biosensor decreased in an order as follows: acetyl cholinesterase/chitosan/functionalized carbon nanotubes biosensor>acetylcholinesterase/functionalized carbon nanotubesbiosensor>chitosan/acetylcholinesterase/functionalized carbon nanotubes biosensor (AChE/CS/F-CNTs/GCE>AChE/F-CNTs/GCE>CS/DAC-AChE/F-CNTs/GCE). The constants of each biosensor apparent electron transfer rate were: k_{s AChE/CS/F-CNTs/GCE}=0.24 s^-1, k_{s AChE/F-CNTs/GCE}=0.23 s^-1, k_{s CS/DAC-AChE/F-CNTs/GCE}=0.22 s^-1. The equivalent circuit model of electrical impedance spectroscopy was R₁(CPE₁(R₂(CPE₂(R₃)))) and the specific device parameters of each circuit model were figured out. The results confirmed that the equivalent circuit can effectively simulate the sensing mechanism of sensor detecting the isoprocarb. It would be a reference for the rapid detection of pesticide residue by biosensors.