A DNAzyme-assisted triple-amplified electrochemical aptasensor for ultra-sensitive detection of T-2 toxin

Herein, an electrochemical aptasensor was constructed for ultra-sensitive determination of T-2 toxin based on Silver ion (Ag + ) -dependent DNAzyme-assisted signal amplification and Gold nanoparticles/Graphene oxide @ manganese dioxide (AuNPs/MnO 2 @GO) nanocomposites. In the presence of Ag + , the secondary structure of the T-2 aptamer is altered via the Ag + mediated coordination of C–Ag + –C base pairs. When T-2 toxin is added, the secondary structure of DNA is changed again, and the trapped Ag + are released. Then, the DNAzyme could repeatedly bind and cleave methylene blue (MB)-modified substrate DNA (S-DNA) in the assistance of Ag + , which leads to a decrease in the electrochemical signal. With the optimal conditions, there is a good linear relationship between the current value and the logarithm of T-2 toxin concentration in the range from 2 fg mL −1 to 20 ng mL −1 , and a detection limit of 0.107 fg mL −1 is obtained. Moreover, the proposed method was successfully applied to measure T-2 toxin in beer, thus showing great potential of this system for food safety and quality control.