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

Abstract 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/MnO2@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.