A SERS-based competitive immunoassay using highly ordered gold cavity arrays as the substrate for simultaneous detection of β-adrenergic agonists

Abstract A surface-enhanced Raman scattering (SERS)-based competitive immunoassay for detecting β-adrenergic agonists (salbutamol, SAL; brombuterol, BRO) was developed. Highly ordered gold cavity arrays (GCA) with adjustable localized surface plasmon resonance and great Raman enhancement were prepared by electrodepositing gold nanoparticles (NPS) to the interstices of polystyrene sphere templates, and then covered by a pre-punched sticker with many holes as detection areas in the assay. The immuno-probe was prepared by immobilizing antibody against SAL (or BRO) and DNA concatamers labelled with SERS reporter on gold NPS. After immunoreaction, the characteristic bands of SERS reporters captured on GCA were measured for quantification of SAL and BRO. The sensitivity was improved by introduction of long DNA concatamers and silver staining due to DNA amplification and strong plasmon coupling between Au and Ag NPS. The LODs for SAL and BRO were 2.0 pg mL−1 and 1.0 pg mL−1, respectively. The recoveries of the assay for SAL and BRO in spiked samples were 96.7∼105.3 % with RSD of 4.9–8.7 %. The results demonstrated that this approach was a sensitive, specific and high-throughput method for simultaneous detection of SAL and BRO, and might be a new platform for the detection of multiple compounds in food and biological fields.