An ultrasensitive competitive immunochromatographic assay (ICA) based on surface-enhanced Raman scattering (SERS) for direct detection of 3-amino-5-methylmorpholino-2-oxazolidinone (AMOZ) in tissue and urine samples

3-Amino-5-methylmorpholino-2-oxazolidinone (AMOZ) is the metabolite of furaltadone (FTD), one kind of nitrofuran antibiotics which have been banned as veterinary drugs due to the potential harmful effects on human health. AMOZ is stable in tissue matrices, and can be used as an indicator for illegal usage of FTD. In this study, a novel ultrasensitive competitive immunochromatographic assay (ICA) based on surface-enhanced Raman scattering (SERS) for direct detection of AMOZ in tissue and urine samples was developed. Monoclonal antibody (mAb) against AMOZ and Raman reporter 4-mercaptobenzoic acid (MBA) dual labelled colloidal GNPs (e.g. Ab-Au-MBA) was prepared, characterized and used as an immunoprobe. The specific Raman scattering intensity of MBA on the test line of the ICA strip was measured for quantitative determination of AMOZ. The assay was completed within 15 min. The values of IC50 and limit of detection (LOD) of the assay for AMOZ were 0.04 ng mL−1 and 0.28 pg mL−1, respectively. There was no cross-reactivity (CR) of the assay with other three nitrofurans and five compounds. The ICA strips could be used for 7 weeks without loss of activity. The tissue and urine samples were spiked with AMOZ and the recoveries of AMOZ were in range of 87.8–105.9% with the relative standard deviations (RSD) of 1.4–9.0% (n = 3). The results demonstrated that the proposed SERS-based ICA was able to directly detect AMOZ with high sensitivity, specificity, stability, precision and accuracy, and might be as a powerful method for the analysis of other analytes in different matrices.