A dual-signal ratiometric electrochemical aptasensor based on Thi/Au/ZIF-8 and catalytic hairpin assembly for ultra-sensitive detection of aflatoxin B1

A dual-signal ratiometric electrochemical aptasensor has been developed  for AFB1 detection using thionine/Au/zeolitic imidazolate framework-8 (Thi/Au/ZIF-8) nanomaterials and catalytic hairpin assembly (CHA) reaction. Thi/Au/ZIF-8 combined with DNA hairpin 2 (H2) was used as a signal probe. [Fe(CN)₆]^3−/4− was served as another signal probe, and the I_Thi/Au/ZIF-8/I_[Fe(CN)6]^3−/4− ratio was for the first time utilized to quantify AFB1. AFB1-induced CHA was used to expand the ratio of electrical signals. In the presence of AFB1, H2/Thi/Au/ZIF-8 bound to the electrode via CHA, enhanced  the current signal of Thi/Au/ZIF-8. H2 contained the DNA phosphate backbone hindered [Fe(CN)₆]^3−/4− redox reaction and resulted in a lower [Fe(CN)₆]^3−/4− current signal. This aptasensor exhibited high specificity for AFB1, a linear range of 0.1 pg mL⁻¹ to 100 ng mL⁻¹, and a detection limit of 0.089 pg mL⁻¹. It demonstrated favorable sensitivity, selectivity, stability, and repeatability. The aptasensor was suitable for detecting AFB1 in peanuts and black tea and holds potential for real sample applications.