A core-satellite self-assembled SERS aptasensor used for ultrasensitive detection of AFB1

A surface-enhanced Raman scattering (SERS) aptasensor was developed using gold nanostars (Au NSs) and Fe 3 O 4 @Au nanoparticles (NPs) for the highly sensitive detection of aflatoxin B 1 (AFB 1 ). Au NSs were modified by the Raman reporter 4-aminothiophenol (PATP) and then coupled with cDNA to act as the capture probes (Au NSs@PATP-cDNA). Fe 3 O 4 @Au NPs were modified with the AFB 1 aptamer (AFB 1 Apt) and used as signal probes (Fe 3 O 4 @Au NPs-AFB 1 Apt). The SERS peak of PATP at 1078 cm −1 was used for quantitative analysis. When the core-satellite nanostructures (Fe 3 O 4 @Au NPs-AFB 1 Apt/cDNA-Au NSs@PATP) were self-assembled by oligonucleotide hybridization, the SERS intensity was significantly enhanced. When AFB 1 was present, AFB 1 Apt specifically binds to AFB 1 , causing the Fe 3 O 4 @Au NPs-AFB 1 Apt and Au NSs@PATP-cDNA to dissociate, resulting in a decrease in the SERS intensity measured after magnetic separation. Under optimal conditions, the limit of detection (LOD) of AFB 1 can be reduced to 0.24 pg/mL. This is attributed to the high affinity of AFB 1 Apt, excellent magnetic separation characteristics, and multiple SERS hotspots. The assay has been validated to perform well in recovery and accuracy by evaluating spiked samples (rice, corn, and wheat) and positive samples (corn, brown rice, and wheat). Graphical