Duplex Detection of Antibiotics in Milk Powder Using Lateral-Flow Assay Based on Surface-Enhanced Raman Spectroscopy

Nowadays, the overuse of antibiotics in cow breeding is a common issue worldwide. Real-time monitoring is critical for antibiotic control of dairy products. Herein, we report a rapid detection method for the duplex detection of two beta-lactam antibiotics (cephalexin and ampicillin) in milk powder using lateral flow (LF) combined with surface-enhanced Raman spectroscopy (SERS). The duplex detection was accomplished using a single test line loaded with two antigens targeting the two corresponding antibody-gold-Raman reporter conjugates. The obtained SERS spectra contributed by the Raman reporter labeled to the two antibodies were analyzed using both peak height method and multiple linear regression (MLR). A good regression fitting was achieved by these two methods ( R 2  = 0.99 and 0.98, respectively). The limit of detection (LOD) was 10 −4  ng/mL for both peak height method and MRL. This study indicated that LF-SERS is a good candidate for real-time multiplex and quantitative analysis for antibiotics in dairy products.