A strategy to protect biological activity and amplify signal applied on time-resolved fluorescence immunochromatography for detecting T-2 toxin

T-2 is one of the most toxic type A trichothecene mycotoxins produced by several fusarium species, which causes a deep harm to the immune system, liver, kidney and brain cells. It is widely found in cereals, cereal products and animal feed. Consequently, it is very important to establish a rapid, efficient and low-cost method for detecting T-2 toxin. In this study, a time-resolved fluorescent immunotomography (TRFIA) paper-based sensor was established. Sheep anti-mouse IgG can protect monoclonal antibody and amplify fluorescence signal. Polystyrene fluorescent microspheres were combined with sheep anti-mouse IgG to prepare fluorescent probes (IgG@Eu). During the detection process, the target-specific monoclonal antibody binds to fluorescence probe (IgG@Eu) to form a complex (mAb-IgG@Eu), which is then captured by the target substance and fixed on the C line. The uncaptured complex (mAb-IgG@Eu) is fixed on the T line by the original coating. Monoclonal antibody can protect its activity by indirect binding with Eu fluorescent beads (FBS). This labeling method improved the binding ratio between the fluorescent microspheres and the monoclonal antibodies. The results of the test strip were compared with liquid chromatography–mass spectrometry (LC–MS/MS), and showed low test line and high recovery rate. With the outstanding augment response, the limit of detection reached 0.01 ng/mL and a wide linear range from 0.0625 to 50 ng/mL was presented. Experimental results show that the detection limit was 0.052 ng/mL and 0.071 ng/mL in corn substrate and feed substrate. The recoveries were between 95.31 and 119.03%, and the relative standard deviations were less than 6.02%. The method was verified by LC–MS/MS, and the results showed that the method had good accuracy.