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(Beijing, China), respectively. were not bound to the target were captured around the T-line, while those that were bound were captured around the C-line. The paper-based sensor reflected the corresponding fluorescence intensity change. Because a single molecule of the deoxynivalenol antibody could bind to multiple Eu-IgGs, this method could amplify the fluorescence signal intensity on the unit antibody and improve the detection sensitivity. The working standard curve of the sensor was established under the optimum working conditions. It showed the lower limit of detection and higher recovery rate when it was applied to actual samples and compared with other methods. This sensor has the advantages of high sensitivity, good accuracy, and good specificity, saving the amount of antibody consumed and being suitable for rapid field detection of deoxynivalenol. Keywords: deoxynivalenol, secondary antibody GSK591 labeling, time-resolved fluorescence immunochromatography, GSK591 field detection method, paper-based sensor 1. Introduction Mycotoxins, which are widely found in various plant-derived foods, are harmful substances produced by the metabolism of fungi such as Aspergillus and Fusarium [1]. Mycotoxins contaminate agricultural products including grain, oil, vegetables, fruits, and nuts [2]. About 31 million tons of grain and oil are lost each year due to mycotoxins in China, and the direct economic loss is as high as 68C85 billion yuan [3]. Mycotoxins exceeding the standard contained in grain and oil products accumulate in the body after being ingested by humans and animals, causing carcinogenic GSK591 changes and seriously endangering their health. At present, more than 300 mycotoxins have been identified, and deoxynivalenol as a common mycotoxin has attracted wide attention. Deoxynivalenol (DON), also known as vomiting toxin, is a derivative of fusobacterium graminea [4], mainly found in corn, wheat, and other food crops [5]. People and animals that consume excessive amounts of DON can experience nausea, diarrhea, vomiting, headache, fever, and other symptoms, hence the name vomiting toxin [6]. DON is usually highly cytotoxic and interferes with immune system development by inhibiting DNA and protein synthesis [7]. In view of the high harmfulness and widespread presence of DON, various countries have formulated corresponding limit standards. There are many methods for the detection of DON. Instrumental analysis methods include high-performance liquid chromatography (HPLC) [8], Liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) GSK591 [4], ultra-performance liquid chromatography (UPLC) [9], gas chromatography with mass spectrometry (GC-MS) [10], and high-performance liquid capillary electrophoresis (HPCE) [11]. HPLC is currently the most commonly used confirmative detection method for mycotoxins [12]. This method has the characteristics of high detection sensitivity, reliable results, and good specificity, and has been widely used in the detection of aflatoxin (AFT), DON, etc. However, most of the traditional instrumental analysis methods have the defects of high instrument price and complex pre-treatment process, and require specialized operators; G-CSF thus, it is difficult to perform rapid field detection. Developed in the 1950s, immunoassay is a qualitative and quantitative method for the detection of compounds, enzymes, and proteins, based on the specific reactions between antigens and antibodies. Immunoassay takes the antibody as the core recognition element, which can specifically bind to the corresponding target object. It has the advantages of high sensitivity, strong specificity, and simple operation [13,14], and has been widely used in the detection of DON. In recent years, time-resolved fluorescence immunochromatography (TRFIA) has attracted extensive attention among researchers due to advantages such as simple operation, fast detection, and low cost [15]. Using lanthanide elements europium (Eu), titanium (Ti), samarium (Sm), and other labeling materials, it replaces fluorescent dyes, enzymes, nano-gold, and other traditional labeling materials to label antibodies and other biological materials, and then carries out an immune reaction in the cellulose GSK591 nitrate (NC) film region. Eu can emit orange fluorescence under ultraviolet lamp irradiation. Time-resolved refers to the detection and quantitative analysis of the signal strength of the object to be tested through wavelength resolution.