DNA tetrahedral scaffold based one-step ratiometric electrochemical detection of aflatoxin B1 in tobacco samples

To effectively monitor Aflatoxin B1 (AFB₁) in tobacco samples, a ratiometric electrochemical biosensor based on DNA tetrahedral scaffold (DTS) and AuNPs/chitosan (CS) modified electrode has been successfully fabricated. The ultra-thin AuNPs not only present a larger specific sensing surface, but also can graft more DTS onto the surface of the electrode. The DTS is directly grated with two strands of AFB₁ aptamer, which leading to a facile one-step detection of AFB₁. In the presence of AFB₁, the current of methylene blue (MB) keeps stable, while the current of ferrocene (Fc) decreases since the target takes away the Fc-labeled aptamer from the electrode surface. The fabricated biosensor can monitor AFB₁ in the linear range of 0.01–1000 pg·mL⁻¹ with the detection limit of (LOD) 2.6 fg·mL⁻¹. More importantly, the biosensor performs well in the detection of AFB1 in tobacco samples with the LOD of 2.86 fg·mL⁻¹. The developed ratiometric electrochemical biosensor displays high selectivity, good stability and high potential in tobacco sample’s AFB₁ detection.