基于铂@金纳米线作为信号放大物的电化学适体传感器检测黄曲霉毒素

目的：为了满足食品质量安全并快速检测食品中黄曲霉毒素B1（AFB1）的含量，构建基于铂@金纳米线（Pt@AuNWs）作为信号放大物的电化学适配体传感器用于花生中AFB1的高灵敏、高选择性检测。方法：首先在玻碳电极（GC）表面修饰纳米金颗粒（AuNPs）构建AuNPs/GC电极，增强基底电极的电催化性能并通过Au﹣S键将互补链（cDNA）固定于AuNPs/GC，其次通过模板法合成Pt@AuNWs使其与适配体结合构建信号探针（记为Pt@AuNWs-apt），最后基于碱基互补配对作用构建电化学适配传感器。当AFB1存在时，其和cDNA竞争结合适配体，导致电极表面的Pt@AuNWs-apt信号探针部分脱落，使电化学适配体传感器催化H₂O₂产生的电流信号降低，从而间接定量检测AFB1。结果：该传感器在0.25 nmol/L cDNA、apt与cDNA孵育40 min、10 mmol/L H₂O₂、0.1 mol/L 磷酸盐浓度pH7.0的测试条件下具有最优的分析性能。该方法具有较宽的线性范围（1～100 ng/mL），检出限为0.41 ng/mL，具有良好的选择性、重现性和稳定性，将该传感器应用于花生样品中进行加标回收实验，结果表明回收率在85.1%～88.0%。结论：构建的电化学适配体传感器可应用于花生中AFB1的检测，在快速检测中具有较好的应用价值。

A reagentless electrochemical sensor for aflatoxin B1 with sensitive signal-on responses using aptamer with methylene blue label at specific internal thymine

Objective: In this study, to meet food quality and safety and rapid determination of aflatoxin B1 (AFB1) content in food, an electrochemical aptamer-based sensor with plantium@gold nanowires (Pt@AuNWs) as the signal amplifier was developed for sensitive and selective detection of AFB1 in peanut. Method: Firstly, Au nanoparticles (AuNPs) were deposited on the surface of glassy carbon electrode (AuNPs/GC) for enhancing the electrocatalytic property of the sensor and linking complementary strand (cDNA) through Au-S bond. Then, the signal probes was constructed via template synthesis of Pt@AuNWs and combination with aptamer (Pt@AuNPs-apt), which could bind to the electrode based on base complementary pairing principle. In the presence of AFB1, it would compete with cDNA to bind aptamer and result in the detachment of some signal probes from the sensor surface, reducing the electrical signals generated by catalyzing H₂O₂, thereby the indirectly quantitative detection of AFB1 was achieved. Result: The sensor showed the best analytical performance with 0.25 nmol/L cDNA, incubating apt and cDNA for 40 min, 10 mmol/L H₂O₂, 0.1 mol/L pH7.0 PBS. Under optimization, this sensor showed good lineariy in the range of 1~100 ng/mL,with the calculated detection limit about 0.41 ng/mL. The present sensor delivered good sensitivity, selectivity and stability. The method was applied to the peanut samples for the recovery experiment and the recovery rate was 85.1%~88.0%. Conclusion: The constructed electrochemical adapter sensor can be applied to the detection of AFB1 in peanuts, and has great potential to be used in rapid detection.