Simultaneous detection of clenbuterol and ractopamine based on multiplexed competitive surface enhanced Raman scattering (SERS) immunoassay

In recent years, the illegal abuse of β2-adrenergic agonists in livestock for growth promotion has been reported frequently. For conventional immunoassay methods, the development of quantitative and simultaneous detection is a great challenge. In this report, a highly sensitive multiplexed immunoassay based on competitive surface-enhanced Raman scattering (SERS) spectroscopy has been developed for the simultaneous detection of clenbuterol and ractopamine. The SERS nanoprobes based on gold nanoparticles (AuNPs) were attached by 4,4′-dipyridyl (DP), clenbuterol antibody, and 2,2′-dipyridyl (BP), ractopamine antibody respectively. The mode of detection of multiple antibodies was implemented by competitive binding between free clenbuterol, free ractopamine and clenbuterol–BSA, ractopamine–BSA immobilized on the substrates with their antibodies labeled on SERS nanoprobes. The results indicated that compared to conventional methods, the proposed method can detect clenbuterol and ractopamine simultaneously over a wide concentration range (1–1000 pg mL−1) with a lower limit of ca. 1.0 pg mL−1, which holds great potential for applications in biochemical analysis and food safety.