The HCR signal amplification-based SERS aptasensor for highly sensitive detection of AFB1

Aflatoxin B1 (AFB1) is a potent carcinogen that poses a serious threat to human health. Therefore, the rapid and accurate detection of AFB1 in grains is crucial. For a highly sensitive aptasensor for AFB1 detection, a method based on the hybridization chain reaction (HCR) and magnetic nanoparticles (Fe₃O₄@Au NPs) strategy for signal amplification through infinite elongation of DNA strands was employed. In the presence of AFB1, AFB1 aptamers (Apt) first bind to AFB1. The unbound aptamers then initiate the HCR, triggering the self-assembly of hairpin DNA strands (H1 and H2) into long double-stranded DNA structures on the surface of the Fe₃O₄@Au NPs. Methylene blue (MB), serving as a signal molecule, can be embedded in double-stranded DNA through π-stacking interactions. Ultimately, the MB embedded within the DNA duplex generates a strong surface-enhanced Raman scattering (SERS) signal on the surface of the Fe₃O₄@Au NPs, which is quantitatively analysed by detecting the MB signal in relation to AFB1. Highly sensitive and specific detection of AFB1 is achieved by monitoring changes in the SERS signal. Under optimised conditions, this method exhibits a linear detection range of 0.001-1000 ng/mL, with a limit of detection (LOD) of 0.947 pg/mL. Furthermore, the proposed method demonstrates excellent selectivity and reproducibility, offering a promising platform for the rapid and highly sensitive detection of AFB1.