黄曲霉毒素M1 (aflatoxin M1,AFM1)是影响乳及乳制品安全的主要因素之一。AFM1具有毒性和强致癌性,且在生产过程中难以消除,令消费者的身体健康受到严重威胁。因此,该研究基于金-二硫化钼 (Au-MoS2) 复合材料构建电化学适配体传感器用于牛奶中AFM1检测。分别采用滴涂法和电沉积法将MoS2和纳米金颗粒修饰在玻碳电极表面,从而得到 Au-MoS2复合材料修饰的电极。Au-MoS2复合材料修饰电极增加了电极导电性,同时二茂铁(ferrocence, Fc) 标记的适配体通过 Au—S固定在Au-MoS2复合材料表面,提高了识别元件适配体的负载量。当存在目标物AFM1时,适配体形成一定构象识别AFM1,导致Fc信号变化,从而实现对 AFM1的定量检测。研究结果表明,MoS2的质量浓度为3.0 mg/mL,沉积电位为-0.2 V,沉积时间为480 s,氯化金浓度为 14 mmol/L 时,Au-MoS2复合材料修饰后的电极性能最佳。同时,以 0.3 μmol/L 的适配体,Mg2+的浓度为0.01 mol/L的条件下与AFM1孵育1.5 h,Fc的响应电流信号最佳。在上述条件下构建电化学适配体传感器的线性范围为 0.015~0.8 μg/L,检出限为 0.014 μg/L。特异性研究结果表明,与干扰毒素 (AFM2、AFB1、AFG1、AFG2) 相比,该传感器对 AFM1的响应较高,说明该传感器具有良好的特异性,有良好的应用前景。
Aflatoxin M1 (AFM1) is the main factor affecting the safety of milk and dairy products.AFM1 is toxic and highly carcinogenic, it is difficult to eliminate during the production process, which poses a serious threat to the health of consumers.Therefore, an electrochemical aptamer sensor based on Au-MoS2 composites was constructed for the detection of AFM1in milk.The MoS2 and gold nanoparticles were modified on the surface of the glassy carbon electrode by drip coating method and electrodeposition method, respectively, to obtain the electrode modified by Au-MoS2 composite.After modifying the Au-MoS2 composite, the conductivity of the electrode increased.The ferrocene-labeled aptamer was immobilized on the surface of the Au-MoS2 composite through the Au-S bond, which improved the loading capacity of the aptamer as the recognition element.In the presence of AFM1, a certain conformation was formed by the aptamer to recognize AFM1, resulting in the change of ferrocene signal.The results shows that the electrode modified by the Au-MoS2 composite exhibits the best performance when the concentration of MoS2 is 3.0 mg/mL, the deposition potential is -0.2 V, the deposition time is 480 s, and the concentration of gold chloride is 14 mmol/L.At the same time, the optimal response current signal of ferrocene is obtained when AFM1is incubated with 0.3 μmol/L aptamer and 0.01 mol/L Mg2+ for 1.5 h.The linear range of the aptamer sensor constructs under the above conditions is 0.015 ~ 0.8 μg/L, and the detection limit is 0.014 μg/L.The specificity results showed that the sensor had a higher response to AFM1 than the interfering toxins (AFM2, AFB1, AFG1, AFG2), indicating that the sensor had good specificity and good application prospects.
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