ECL cytosensor for sensitive and label-free detection of circulating tumor cells based on hierarchical flower-like...

The development of sensitive and efficient cell sensing strategies to detect circulating tumor cells (CTCs) in peripheral blood is crucial for the early diagnosis and prognostic assessment of cancer clinical treatment. Herein, an array of hierarchical flower-like gold microstructures (HFGMs) with anisotropic nanotips was synthesized by a simple electrodeposition method and used as a capture substrate to construct an ECL cytosensor based on the specific recognition of target cells by aptamers. The complex topography of the HFGMs array not only catalyzed the enhancement of ECL signals, but also induced the cells to generate more filopodia, improving the capture efficiency and shortening the capture time. The effect of topographic roughness on cell growth and adhesion propensity was also investigated, while the cell capture efficiency was proposed to be an important indicator affecting the accuracy of the ECL cytosensor. In addition, the capture of cells on the electrode surface increased the steric hindrance, which caused ECL signal changes in the Ru(bpy)₃²⁺ and TPrA system, realizing the quantitative detection of MCF-7 cells. The detection range of the sensor was from 10² to 10⁶ cells mL^-1 and the detection limit was 18 cells mL^-1. The proposed detection method avoids the process of separation, labeling and counting, which has great potential for sensitive detection in clinical applications.