Selective aptasensor of deoxynivalenol based on dual signal enhancement of thionine electrochemistry using silver nanoparticle-loaded label at gold nanoparticle-loaded electrodes

In this work, an efficient sensing platform deoxynivalenol (DON) detection was constructed through monitoring the current change of a competitive mechanism triggered by DON, leading the signal label detached from the electrode surface by square-wave voltammetry using thionine (Thi) as a redox indicator. The complementary strand of aptamer (cDNA) and Thi were loaded onto Fe/Ni bimetallic metal-organic framework loaded with sliver nanoparticles (AgNPs@FeNi-MOF) to construct AgNPs@FeNi-MOF/cDNA/Thi signal probes. In the presence of DON, the aptamer sequence was more predisposed to form an aptamer-DON complex, resulting in the displacement of the cDNA. The signal probe was subsequently released, leading to a decrease in the signal intensity of Thi. Notably, AgNPs@FeNi-MOF has a larger electroactive specific surface area and is able to load more cDNA and thi, which can amplify the signal. Under the optimal experimental conditions, the developed sensor exhibits a good linear response in the range of 1 × 10^-2 to 1 × 10⁴ pg/mL, with a limit of detection (LOD) of 5.68 fg/mL and has good selectivity, reproducibility and stability.