Rapid Detection of Ractopamine and Salbutamol in Swine Urine by Immunochromatography Based on Selenium Nanoparticles

PURPOSE: The purpose of this study was to establish a lateral flow immunoassay using selenium nanoparticles (Se-NPs) as a probe to detect ractopamine (RAC) and salbutamol (SAL) in swine urine. METHODS: SDS and PEG were used as templates to prepare Se-NPs; anti-RAC monoclonal antibodies or anti-SAL monoclonal antibodies were labelled with Se-NPs; and rapid detection kits were prepared. The sensitivity, specificity, and stability were measured, and actual samples were analysed. RESULTS: The Se-NPs were spherical with a diameter of 40.63 ± 5.91 nm, and were conjugated successfully with an anti-RAC antibody to give a total diameter of 82.33 ± 17.91 nm. The detection limit of a RAC kit in swine urine was 1 ng/mL, and that of a SAL kit was 3 ng/mL. Both procedures could be completed within 5 minutes. No cross-reaction occurred with clenbuterol, bambuterol and phenylethanolamine A. Samples were tested consistently across different batches of kits for swine urine. The results of the kits were identical to those of actual clinical samples analysed by ELISA, and the coincidence rate was 100%. CONCLUSION: The assay kit does not require any special device for reading the results, and the readout is a simple colour change that can be evaluated with the naked eye. It is easy to operate, sensitive, specific, and stable This kit is suitable for the rapid and real-time detection of RAC and SAL residues in swine urine samples. CLINICAL TRIAL REGISTRATION: Swine urines samples were used under approval from the Experimental Animal Ethics committee of the Joint National Laboratory for Antibody Drug Engineering, Henan University.