A surface-enhanced Raman scattering aptasensor for ratiometric detection of aflatoxin B1 based on graphene oxide-Au@Ag core-shell nanoparticles complex

Aflatoxin B1 (AFB1) has the strongest carcinogenesis and mutagenesis effects. Herein, a novel ratiometric surface-enhanced Raman scattering (SERS) aptasensor based on graphene oxide (GO) as a corrective internal standard (IS) and signal amplifier was constructed for reliable detection of AFB1. 4-Mercaptobenzoic acid as Raman reporter embedded in Au@Ag core-shell nanoparticles and AFB1aptamer conjugated to the Ag shell acted as the signal probes (Au-4MBA@Ag NPs-AFB1apt). AFB1apt was attached to the surface of GO with Raman signals modified Au NPs/Indium tin oxide glass (GO/Au NPs/ITO) via pi-pi stacking interaction, facilitating further amplification of the signal. With an increase of AFB1 concentration (0.0001 ng/mL-100 ng/mL), the probes were released owing to the affinity of aptamers, causing the decreased 4-MBA intensity (I4-MBA) and unchanged GO intensity (IGO). Therefore, the quantitative test was achieved based on the ratiometric value (I4MBA/IGO). A good negative correlation (R2 = 0.992) was achieved and the limit of detection (LOD) was as low as 0.1 pg/mL, proving the proposed sensor can become an efficient analytical tool and shows a bright application prospect in the food detection field.