The widespread presence of mycotoxins in nature not only poses a huge health risk to people in terms of food but also causes incalculable losses to the agricultural economy.

The polypeptide antibiotics colistin (COL) and bacitracin (Baci) are extensively used as veterinary drugs and feedstock additives in the livestock industry, which inevitably causes residues in animal-origin food, which can accelerate human tolerance to antibiotics. In this study, a portable lateral flow immunoassay (LFIA) for the simultaneous determination of COL and Baci residues in milk was developed. The replacement of gold nanoparticles used in the traditional LFIA with fluorescent microspheres (FMs) to label monoclonal antibodies (mAbs) allowed qualitative and quantitative analyses within a few minutes. Based on the principle of competitive binding to FM-labelled mAbs between analytes in samples and fixed antigens on the membrane, the assay provided qualitative cut-off values of 100 and 50 ng mL⁻¹ for Baci and COL in milk samples. Furthermore, a strip reader-based semi-quantitative detection system could detect lower limits of 7.85 and 1.89 ng mL⁻¹ for Baci and COL, respectively. In conclusion, the proposed multiplex LFIA immunosensor provides an auxiliary analytical tool for the rapid and simultaneous screening of COL and Baci in large cohorts of samples.

We designed and synthesized novel haptens to produce monoclonal antibodies (mAb) against vitamin B₆ (VB₆). A group-specific mAb (2F9) that recognized pyridoxine (PN), pyridoxamine (PM), and pyridoxal (PL) was prepared using a homologous strategy with 50% maximal inhibitory concentration (IC₅₀) values of 106.60, 250.57, and 400.11 ng/mL, respectively. Based on this, a gold nanoparticles (AuNPs)-based immunochromatographic strip (ICS) test was established for the detection of VB₆ in energy drinks and B-vitamin complex tablets. The developed ICS test results could be semi-quantitatively evaluated by the naked eye within 10 min, and displayed the visual limit of detection (vLOD) values of 250, 500, and 1,000 ng/mL for PN, PM, and PL, respectively. For quantitative analysis, the results obtained by strip reader, with calculated LOD values for PN, PM, and PL were 14.10, 55.58, and 56.25 ng/mL, respectively. Commercial energy drinks and B-vitamin complex tablet samples were detected by the strips and the results were confirmed with high-performance liquid chromatography. Overall, the developed AuNPs-based immunochromatographic sensor was suitable and promising for the group-specific recognition and rapid detection of VB6 in fortified foods and dietary supplements.

The developed time-resolved fluorescence immunochromatographic assay can be widely applicable as an ultrasensitive, rapid detection method for FB ₁ in grains.

In this study, the monoclonal antibody-based indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and an immunochromatographic strip assay were developed for the rapid screening of robenidine hydrochloride (ROBH) in samples. The 50% inhibitory concentration (IC₅₀) of ROBH was 0.927 ng mL⁻¹, and the standard curve showed a linear correlation coefficient of 0.99932. There was no cross-reaction between ROBH and other commonly used anticoccidial drugs, which indicated that the monoclonal antibody had high specificity. The recoveries of ic-ELISA were in the range of 87.8% to 102.0%. The immunochromatographic strip assay displayed cut-off values of 10, 5 and 10 ng g⁻¹ for shrimp, chicken breast and chicken liver samples, respectively. In addition, the results can be obtained within 10 min by naked eye observations. And in sample analysis, the results of ic-ELISA and the immunochromatographic strip assay were in accordance with those of LC-MS/MS. Thus, the ic-ELISA and immunochromatographic strip assay are effective methods for the detection of ROBH in shrimp, chicken breast and chicken liver samples.

A mAb against dicofol was developed to prepare ICAs for the detection of dicofol residues in fruit and vegetables. The ICA method gave a visible LOD of 50 ng g⁻¹, and a cut-off value of 500 ng g⁻¹ for the detection of dicofol in foods with the naked eye.