Electrochemical detection of tumor cells based on proximity labelling-assisted multiple signal amplification†

Malignant tumors are the second leading cause of human deaths worldwide, and early cancer screening and diagnosis can effectively reduce cancer mortality. Herein, we propose a new electrochemical method for the highly sensitive detection of MUC1-positive tumor cells based on proximity labelling-assisted multiple signal amplification. Specifically, a MUC1 aptamer-modified electrode was prepared for capturing MUC1-positive tumor cells, followed by binding of G4-DNA strands to the cells with the aid of a mild reduction reaction. A hemin/G4-DNA complex was then formed and acted as a mimic of horseradish peroxidase, catalysing the proximal labelling of tyramine-modified gold nanoparticles to induce silver-enhanced electrochemical signal amplification. Electrochemical results demonstrated that the method was able to specially identify MUC1-positive tumor cells and generate corresponding electrochemical responses in the range of 100 cells per mL to 1 × 10⁶ cells per mL with a detection limit of 21 cells per mL. Furthermore, the method displayed good stability and anti-interference performance in complex serum environments. Therefore, our work may provide an effective tool to improve the accuracy of cell-based tissue examination and liquid biopsy for early diagnosis of cancers in the future.