比率电化学传感技术在农产品真菌毒素检测中的研究进展

真菌毒素广泛存在于霉变农产品中，具有致癌、致畸、致突变等危害，受其污染的农产品已被世界卫生组织列为食源性疾病的主要来源，但农产品中真菌毒素检测存在基质复杂、灵敏度要求高等难题。电化学传感技术操作简单、成本低、灵敏度高以及分析速度快，在农产品真菌毒素检测中应用广泛，而将比率策略与电化学传感结合发展的比率电化学传感技术可以进一步提高传感器在复杂环境中的分析准确度和可靠性。该研究主要从直接传感、免疫传感、DNA传感及适配体传感等4个方面综述了近3年来（2018－2021年）比率电化学传感技术的研究进展，系统讨论了它们的信号产生策略、传感机理及其在农产品真菌毒素检测方面的应用，总结了不同传感模式中所用识别元件、传感材料、实际样品及检测真菌毒素的分析性能，并讨论了不同传感模式的优缺点。最后，分析了比率电化学传感技术在农业传感领域的瓶颈问题，如识别元件的开发，多种真菌毒素的同时检测，农产品的现场、实时检测等，指出开发便携式设备实现不同真菌毒素的现场、同时、快速检测是本领域的重要发展方向，以期为农产品中真菌毒素高效检测技术提供参考。

Research progress on ratiometric electrochemical sensors for the detection of mycotoxins in agricultural products

Mycotoxins have been listed as the main sources of foodborne diseases by the World Health Organization, due to their high teratogenicity, nephrotoxicity, and carcinogenicity. Electrochemical sensing technology can be used to rapidly detect the mycotoxins in agricultural products, in terms of portability, low cost, and high sensitivity. Generally, the electrochemical sensors can be selected to quantify the analytes simply by a single electrical signal susceptible to interference from some intrinsic or extrinsic factors. The ratiometric strategy with dual-signal responses has been recently applied in electroanalytical sensors, in order to deal with the unreliable trace detection from traditional single-signal sensors. The ratiometric electro-analytical sensors shared the dual signals, where the ratio of the two signals was served as a yardstick, instead of a single signal. The ratiometric strategies can be divided into the single- and dual-signal dependence on analytes. In the single-signal dependence, only one single signal was dependent on the analytes, while another signal remained unchanged. In the dual-signal dependence, both signals were dependent on the analytes, where their intensities exhibited correspondingly increasing and decreasing changes simultaneously. Theoretically, such ratiometric strategies can provide an intrinsic built-in correction to effectively reduce or eliminate the fluctuations from the intrinsic background signals, and then greatly improve the accuracy and reliability of the electrochemical sensors in complex detection conditions. This review highlighted the recent advances in ratiometric electrochemical sensors over the past three years (2018-2021). Four categories were divided as follows. 1) Direct sensors, which mainly utilize the electrode materials to directly oxidize the analyte and internal-reference substance to obtain the dual redox signals; 2) Antibody-based sensors, which use the antigen and antibody as the recognition elements to establish the dual-signal readout immunoassay; 3) DNA-based sensors, which use the DNA as the recognition element and the specific hybridization between complementary and target DNA to cause the changes in the electrical signals of the system for the ratiometric detection of targets; 4) Aptamer-based sensors, which utilize the specific binding between the aptamer and target to cause the changes in the electrical signals. This review summarized the signal generation strategies and analytical applications, particularly for the detection of mycotoxins in agricultural products. Furthermore, a systematic evaluation was performed on the recognition elements, sensing materials, real samples, and the analytical performances for the detection of mycotoxins in various sensing modes. Finally, the bottleneck and development trends were addressed for the ratiometric electrochemical sensing technology in the field of agricultural sensing, such as the development of recognition elements, the simultaneous detection of multiple mycotoxins, the on-site and real-time detection of mycotoxins in agricultural products, etc. The portable devices can be expected to realize the on-site, simultaneous, and rapid detection of various mycotoxins. This review can provide a strong reference for the mycotoxins detection techniques in agricultural products.