A core-satellite self-assembled SERS aptasensor used for ultrasensitive detection of AFB1
摘要
A surface-enhanced Raman scattering (SERS) aptasensor was developed using gold nanostars (Au NSs) and Fe3O4@Au nanoparticles (NPs) for the highly sensitive detection of aflatoxin B1 (AFB1). 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). Fe3O4@Au NPs were modified with the AFB1 aptamer (AFB1 Apt) and used as signal probes (Fe3O4@Au NPs-AFB1 Apt). The SERS peak of PATP at 1078 cm−1 was used for quantitative analysis. When the core-satellite nanostructures (Fe3O4@Au NPs-AFB1 Apt/cDNA-Au NSs@PATP) were self-assembled by oligonucleotide hybridization, the SERS intensity was significantly enhanced. When AFB1 was present, AFB1 Apt specifically binds to AFB1, causing the Fe3O4@Au NPs-AFB1 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 AFB1 can be reduced to 0.24 pg/mL. This is attributed to the high affinity of AFB1 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 Abstract