Sensitive and Matrix-Tolerant Lateral Flow Immunoassay Based on Fluorescent Magnetic Nanobeads for the Detection of Clenbuterol in Swine Urine

The lack of sensitivity and poor matrix tolerance are the main bottlenecks of the lateral flow immunoassay (LFIA). Here, a sensitive and matrix-tolerant method that integrated immunomagnetic separation and fluorescent lateral flow immunoassay (IMS–FLFIA) based on fluorescent magnetic nanobeads was developed to detect the clenbuterol (CLE) residue in swine urine. The limit of detection (LOD) of IMS–FLFIA is 4 times lower than that of traditional colloidal gold LFIA. This method, which exhibits similar LOD and linearity range in both phosphate-buffered saline and urine swine, is highly correlated with liquid chromatography–tandem mass spectrometry for the detection of real swine urine samples. The result indicated that IMS–FLFIA has a universal resistance to the swine urine matrix. The merits of this assay, high sensitivity, matrix tolerance, accuracy, and specificity, ensure a promising future in detection of veterinary drug residues.