Fe3O4@Au@Ag nanoparticles as surface-enhanced Raman spectroscopy substrates for sensitive detection of clenbuterol hydrochloride in pork with the use of aptamer binding

Clenbuteml hydrochloride (CLB), a kind of p-agonist, has been illegally used as a feed additive for growth promotion in the food industry in many countries. Herein, surface-enhanced Raman scattering (SERS) combined with aptamer recognition was used for the ultrasensitive and quantitative detection of CLB. Fe3O4@Au@Ag nanoparticles displaying strong SERS enhancement were synthesized and used as the active substrate. Aptamer against CLB was immobilized on the surface of the substrate to form the capture probe. The complementary DNA (cDNA) was linked to gold nanoparticles (AuNPs) carrying the Raman reporter 4-mercaptobenzoic acid (4-MBA) to form the signal probe. The detection of CLB was carried out by competitive binding between free CLB and cDNA linked on the signal probe with the aptamer immobilized on the capture probe. The SERS intensity was significantly improved by the coupling effect between the Fe3O4@Au@AgNPs and AuNPs, resulting in high sensitivity for the quantification assays with a limit of detection of 0.003 ng mL(-1). The recoveries of the CLB from spiked pork samples were 90.7-108.0% and the coefficients of variation (CV%) were 2.2-3.1%, demonstrating the high precision and accuracy of the assay.