Modular lateral flow test systems for the competitive immunodetection of different classes of antibiotics in meat

A modular concept of competitive lateral flow immunoassay was proposed and developed for the detection of antibiotics belonging to different classes. The kit for assay implementation comprises a universal test strip and changeable soluble immune reactants of varying specificities. The test strip contains streptavidin immobilized in the analytical zone and a conjugate of gold nanoparticles (GNPs) with anti-species antibodies. Specific immune reactants, antibodies against the corresponding antibiotics and a conjugate of the antibiotic's derivative with a protein carrier are added to the tested sample and incubated. The subsequent contact of the test strip with the reaction mixture initiates a lateral flow process with the coloration of the analytical zone depending on the content of antibiotics. The proposed technique was realized for the detection of antibiotics in meat. The detection limits were 2.7 ng mL^-1 (visual) and 0.2 ng mL^-1 (instrumental) for tylosin, 1.8 ng mL^-1 (visual) and 0.02 ng mL^-1 (instrumental) for tetracycline, and 17 ng mL^-1 (visual) and 0.4 ng mL^-1 (instrumental) for lincomycin. Recovery values of antibiotics in meat were in the range of 90% to 110%. The obtained results demonstrate the efficiency of the proposed approach for the simple detection of a wide range of low-molecular-weight analytes. The developed kit enables the possibility of simply changing specific reactants for the detection of different antibiotics and excludes the necessity to prepare different variants of test strips as done in traditional lateral flow immunoassays. In this way, the necessity to select conditions for immobilization of reagents on membranes and for obtaining GNP-labeled reagents for each new target analyte is excluded.