Exonuclease I-assisted recycling strategy coupled with Cu-Pt bimetallic nanozyme catalysis for ultrasensitive electrochemical aptasensing of deoxynivalenol

In this work, a novel electrochemical aptasensor was constructed for the sensitive detection of DON by integrating the synergistic effect between the catalytic signal enhancement of Cu-Pt NPs and Exo I-assisted cyclic amplification, with an MWCNTs-AuNPs modified electrode serving as the sensing platform. Cu-Pt NPs with outstanding peroxidase-like catalytic activity were synthesized and used as signal probes to catalyze the substrate, generating significantly enhanced electrochemical signals. Meanwhile, Exo I enabled target recycling via specific strand cleavage. The two amplification mechanisms synergistically amplify the detection signal by enhancing catalytic efficiency and increasing cycle numbers. MWCNTs-AuNPs possess both a high specific surface area and superior conductivity, facilitating efficient electron transfer and biomolecule immobilization. In the presence of DON, the Exo I mediated recycling reaction is triggered, which leads to a reduction in the amount of the immobilized Cu-Pt NPs signal probes on the aptasensor surface. Under optimal conditions, the proposed aptasensor demonstrated a detection range from 0.1 to 500 ng/mL, and a low detection limit of 0.06 ng/mL, along with high selectivity, reproducibility, and stability for DON detection. Furthermore, the proposed aptasensor achieved satisfactory recovery rates in real sample analysis, indicating its promising potential for practical applications.