Near-infrared fluorescence-based multiplex lateral flow immunoassay for the simultaneous detection of four antibiotic residue families in milk

In this study, we developed a novel near-infrared fluorescence based multiplex lateral flow immunoassay by conjugating a near-infrared label to broad-specificity monoclonal antibody/receptor as detection complexes. Different antigens were dispensed onto separate test zones of nitrocellulose membrane to serve as capture reagents. This assay format allowed the simultaneous detection of four families of antibiotics (beta-lactams, tetracyclines, quinolones and sulfonamides) in milk within 20 min. Qualitative and quantitative analysis of target antibiotics were realized by imaging the fluorescence intensity of the near infrared label captured on respective test lines. For qualitative analysis, the cut-off values of beta-lactams, tetracyclines, quinolones and sulfonamides were determined to be 8 ng/mL, 2 ng/mL, 4 ng/mL and 8 ng/mL respectively, which were much lower than the conventional gold nanoparticle based lateral flow immunoassay. For quantitative analysis, the detection ranges were 0.26-3.56 ng/mL for beta-lactams, 0.04-0.98 ng/mL for tetracyclines, 0.08-2.0 ng/mL for quinolones, and 0.1-3.98 ng/mL for sulfonamides, with linear correlation coefficients higher than 0.97. The mean spiked recoveries ranged from 93.7% to 108.2% with coefficient of variations less than 163%. These results demonstrated that this novel immunoassay is a promising approach for rapidly screening the four families of antibiotic residues in milk. (C) 2015 Elsevier B.V. All rights reserved.