SERS aptasensor utilizing aptamer-conformation-mediated regulation of Au dumbbell dimers for the ultrasensitive detection of β-phenethylamine in foods

Surface-enhanced Raman spectroscopy (SERS) is a powerful tool for the detection of target analytes in foods, with the realization of "hot spots" between plasmonic metal nanoparticles (NPs) being critical for ultrasensitive detection. Herein, we proposed a new aptamer conformation-mediated SERS "hot spots" strategy. Au NPs were functionalized with strands of complementary DNA containing β-phenethylamine aptamers and the Raman reporter 4-mercaptobenzonitrile (4-MBN). This allowed DNA-driven self-assembly of an Au dumbbell dimer-based SERS aptasensor for the detection of the β-phenethylamine. After selective recognition of β-phenethylamine by the aptamer, the aptamer folded, bringing AuNPs in the dimers close together to create SERS "hot spots". This produced an intense SERS signal in the "biologically silent" region for 4-MBN (2225 cm−1), the intensity of which increased linearly with the logarithm of the β-phenethylamine concentration. Under the optimized conditions, the linear range of SERS aptasensor was 10−6 to 10−2 mg L−1, with a low limit of detection of 3.8 × 10−7 mg L−1. Further, the developed SERS aptasensor was successfully employed to determine the β-phenethylamine in a range of food samples, with the results being identical to those obtained using a high-performance liquid chromatography method.