Target-induced DNAzyme-driven DNA Walker triple signal amplification aptasensor for sulfanilamide detection based on Pt@Pd nanocubes and Au nanoflowers/ribbon-like PEI-CoSe2

Given the urgent need to monitor drug residues in food sample, a DNAzyme-driven DNA Walker electrochemical aptasensor based on Thi-labeled Pt@Pd NCs as signal probe and Au NFs/PEI-CoSe2 was constructed. Pb(II)dependent DNAzyme sequence was split into two segments artificially and assigned to a specific location to trigger target-induced DNAzyme-driven DNA Walker mechanism signal amplification. In the presence of sulfanilamide, the signal amplification strategy is successfully triggered and catalyze multiple cleavage of signal probes, thereby resulting in signal amplification. PEI-CoSe2 composite Au nanoflowers (NFs) as electrode modification material exhibited a great improvement in sensing performance. Thi-labeled Pt@Pd nanocubes (NCs) as signal probes accurately reflect the changes in signal and the amount of Pt was optimized to obtain the best performance. Under optimal conditions, the peak current was linearly related to the logarithm of sulfanilamide concentration in the range of 10 pg/mL similar to 1 mu g/mL with a low detection limit of 3 pg/mL. Moreover, the proposed aptasensor exhibited satisfactory specificity, reproducibility and stability toward sulfanilamide, has been applied to the detection of sulfanilamide in beef samples and showed rewarding recovery varied from 91.03 % to 96.40 %.