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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 establish a rapid and sensitive method for the detection of ochratoxin A (OTA) by one-step electrochemical sensor based on the target-induced conformational transformation of nucleic aptamers. Methods One side of the aptamer was labeled with thiol group and the other side was labeled with carboxyferrocene. The aptamer was immobilized on the electrode surface through Au-S covalence. When the target molecule OTA was added, the conformational change was induced and the ferrocene was far away Electrode surface, the electrical signal is reduced. Results The best time for OTA and aptamer was 20 min. In the concentration range of 0.1-100 ng / mL, the logarithm of the electrical signal generated by the sensor is linear with the logarithm of OTA concentration, with a correlation coefficient of R ~ 2 of 0.9908 and a detection limit of 0.08 ng / mL. OTA recoveries ranged from 89.2% to 106.9% at spiked levels of 5, 10 and 50 ng / mL. The reaction electrode was washed with 10% isopropanol in PBS (pH 7.4) buffer solution and used continuously for 8 times. The relative standard deviation of OTA was 4.2%, indicating that the sensor could be regenerated and reused. Conclusion The sensor has high sensitivity and selectivity, simple operation, less sample consumption, easy array detection and instrument miniaturization, which can be used for the detection of OTA-contaminated agricultural products.