基于电化学适体传感器的一步法快速检测赭曲霉毒素A

One-step rapid detection of ochratoxin A by the electrochemical aptasensor

目的构建一种基于目标物诱导核酸适配体构象变换的电化学传感器一步法快速灵敏检测赭曲霉毒素A(ochratoxinA,OTA)的含量。方法适配体一端标有巯基,另一端标有羧基二茂铁,通过Au-S共价作用将适配体固定到电极表面;当加入目标分子OTA时,引起构象变换,使二茂铁远离电极表面,电信号降低。结果OTA与核酸适配体最佳作用时间为20 min。在0.1~100 ng/mL浓度范围内,传感器产生的电信号和OTA浓度的对数呈线性关系,相关系数R^2为0.9908,检测下限达0.08 ng/mL。在5、10和50 ng/mL 3个浓度加标水平下,OTA回收率为89.2%~106.9%。选用含10%异丙醇的PBS(pH 7.4)缓冲溶液清洗反应电极并连续使用8次,测定OTA的相对标准偏差为4.2%,说明该传感器可再生重复使用。结论该传感器具有较高的灵敏度和选择性,操作简单、样品消耗少、易实现阵列化检测和仪器微型化,可用于OTA污染的农产品的检测。

Objective To construct a method of one-step electrochemical aptasensor based on the conformation transformation of aptamer induced by the target for the determination of ochratoxin A（OTA）.Methods The aptamer with sulphur and carboxyl ferrocene at both terminals was covalently immobilized on the surface of the electrode by self-assembly.After adding the target molecular OTA,the conformation transformation would occur,causing ferrocene away from the electrode surface and reducing the electrical signal.Results The optimal reaction time between aptamer and OTA was 20 min.The developed electrochemical aptasensor had a good logarithmic linear relationship between the electrical signal produced by the sensor and OTA concentration in the range of 0.1~100ng/mL,with the correlation coefficient of 0.9908.The limit of detection（LOD） was 0.08 ng/mL.The recoveries of OTA spiked at 3 levels of 5,10,and 50 ng/mL were 89.2%~106.9%.When the electrode was cleaned by PBS buffer containing 10%isopropyl alcohol（pH 7.4） and used 8 times,the relative standard deviation of OTA was determined as 4.2%,which showed that the sensor could be renewable reuse.Conclusion The proposed aptasensor exhibits such advantages as high sensitivity and selectivity,simple operation,low sample consumption and compatibility with array format and miniaturization,which can be used for the determination of OTA contaminated agro-products.