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

Abstract

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.