Development of ic-ELISA and lateral-flow immunochromatographic assay strip for the detection of vancomycin in raw milk and animal feed

Abstract

A highly sensitive monoclonal antibody (mAb) 3H4 against vancomycin (VAN) was prepared. Indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and lateral-flow immunochromatographic assay (ICA) were developed based on the mAb. The 50% inhibition concentration (IC50) value and limit of detection (LOD) value of ic-ELISA method for vancomycin were 0.59 and 0.06 ng/mL, and for norvancomycin were 1.51 and 0.13 ng/mL under optimized conditions as pH 7.4, 0.4% (m/v) NaCl, and 5% (v/v) acetonitrile. In lateral-flow ICA, the visual limit of detection (vLOD) value and cut-off values for vancomycin were 1 and 2.5 ng/mL, and for norvancomycin were 5 and 10 ng/mL under optimized conditions as pH 8.6 with 1 mg/mL coating antigen and 1 µg/mL gold nanoparticle-labeled mAb. In raw milk and animal feed samples, recovery rates from ic-ELISA ranged from 89.2% to 121.6%. The vLOD and cut-off value were 5–10 ng/g and 100–200 μg/kg, respectively. Therefore, both methods were sensitive, rapid, and effective for the on-site detection and rapid mass screening of samples.