Core-shell AuNRs@Ag-enhanced and magnetic separation-assisted SERS immunosensing platform for amantadine detection in animal-derived foods

Abstract

A core-shell AuNRs@Ag-enhanced and magnetic separation-assisted surface-enhanced Raman spectroscopy (SERS) immunosensing platform was developed for rapid, accurate and sensitive detection of amantadine (AMD) contaminant in animal-derived foods. This SERS immunosensing platform works in a competitive strategy, which used the 4-mercaptobenzoic acid (4-MBA) labeled AuNRs@Ag with AMD-BSA immobilized as a signal probe and magnetic beads (MBs) with mAbs covalently attached to the surface as a capture probe. It was found that the synthesized core-shell AuNRs@Ag could significantly enhance the SERS signal of the reporter 4-MBA (EF: 2.91 × 107), and the coating of Ag shell effectively avoided the shedding of 4-MBA, thereby improving the sensitivity and stability of SERS analysis. The use of MBs not only overcomes the shortcoming of mAbs inactivation, but also simplifies the detection procedure, improving the detection efficiency. This SERS immunosensing platform was demonstrated to have a linear response in a wide AMD concentration range of 0.01–50 μg/L with high sensitivity (limit of detection (LOD): 0.0038 μg/L) and specificity. For actual animal-derived foods (chicken, milk, egg), acceptable recoveries of AMD (82.0–106.0%) at three spiked levels (0.5, 5, 50 μg/kg) were obtained with relative standard deviation (RSD, n = 5) ranging from 4.7% to 9.6%. The whole detection procedure can be completed within 30 min. These results demonstrated that the proposed SERS immunosensing platform was reliable and sensitive in the quantitative analysis of AMD and could be applied as an effective tool for rapid screening for AMD-contaminated foods.