Ultrasensitive SERS aptasensor using Au@Ag bimetallic nanorod SERS tags for the selective detection of amantadine in foods

Herein, a novel surface enhanced Raman spectroscopy (SERS) aptasensor was developed for amantadine (AMD) detection, based on magnetite nanoparticles coated with polyethylenimine, silver nanoclusters and aptamers (Fe3O4@PEI@AgNC-apt) as the capture probe and complementary DNA-modified gold nanorods (AuNRs@4-MPBA@Ag-c-DNA containing 4-mercaptophenylboric acid molecules) as the reporter probe. In the presence of AMD, the AMD and the reporter probe competed for the aptamer on the surface of the capture probe, resulting in the reporter probe detaching from the capture probe leading to a decrease in intensity of the SERS signal at 1067 cm−1 for 4-MPBA. Under optimal conditions, a good linear relationship was established between the SERS intensity at 1067 cm−1 and the logarithm of the AMD concentration over the range 10−6-102 mg L−1, with a LOD of 0.50 × 10−6 mg L−1. The AMD levels in spiked samples were evaluated using the SERS aptasensor, with good recoveries ranging from 90.57% to 113.49% being obtained.