One-pot synthesis of platinum-copper pyramid alloy catalyst with multiple branches for the electrochemical detection of circulating tumor DNA

Abstract

Circulating tumor DNA (ctDNA) is one of the important biomarkers for early or minimally noninvasive cancer monitoring. In this work, we constructed a ctDNA electrochemical biosensor based on a platinum-copper pyramid alloy catalyst with multiple branches (PtCu). HRTEM and XRD characterizations demonstrated that the PtCu exhibited the homogeneous morphology structure of a pyramid with multiple branches and showed a state of alloy. Further, the PtCu was used as a label of DNA signal probes (SPs) to form SPs-label via PtS bonds. After the immobilization of capture probes (CPs) on the gold electrode surface, the target DNA (tDNA) and SPs-label were hybridized stepwise with each other, resulting in a sandwich-like structure. Due to the special morphology and bimetallic synergistic effect, the prepared PtCu displayed outstanding catalytic capacity, which can largely amplify the current signal. By recording the catalytic current response signal of PtCu toward H2O2, the fabricated biosensor exhibited a wide linear range of 10 nM to 10 aM and a low detection limit of 7.86 aM (S/N = 3) toward tDNA. The selectivity for co-existing interference was also fascinating. Besides, the biosensor provided good stability, reproducibility, and satisfying recovery. These results demonstrated the promising application of the biosensor in ctDNA detection.