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

Abstract

ABSTRACTA 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.