A novel cytosensor was constructed for the ultrasensitive detection and nondestructive release of circulating tumor cells (CTCs) by combining Au nanoparticles-loaded two-dimensional bimetallic PdMo (2D Au@PdMo) nanozymes and electrochemical reductive desorption. The 2D Au@PdMo nanozymes possessed high-efficiency peroxidase-like activity and were assembled with an aptamer composed of a thiol-modified epithelial specific cell adhesion molecule (EpCAM) to strengthen CTCs adhesion. Moreover, the electrode surface was decorated with highly fractal Au nanostructures (HFAuNSs) composites due to the similarity in fractal nanostructure with the CTCs membrane to enhance the CTCs anchoring efficiency and release capability. The captured CTCs could be further efficiently dissociated and nondestructively released from the modified electrodes upon electrochemical reductive desorption. The designed cytosensor showed an excellent analytical performance, with a wide linear range from 2 to 1 × 10⁵ cells mL⁻¹ and low limit of detection (LOD) of 2 cells mL⁻¹ (S/N = 3) at the working potential in the range −0.6 to 0.2 V. A satisfactory CTCs release reaching a range of 93.7–97.4% with acceptable RSD from 3.55 to 6.41% and good cell viability was obtained. Thus, the developed cytosensor might provide a potential alternative to perform CTC-based liquid biopsies, with promising applications in early diagnosis of tumors.

Graphical abstract

中文翻译：

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使用金纳米粒子和适体修饰的 PdMo 二维纳米酶对循环肿瘤细胞进行可逆捕获和伏安法测定

通过结合负载金纳米颗粒的二维双金属 PdMo (2D Au@PdMo) 纳米酶和电化学还原解吸，构建了一种用于循环肿瘤细胞 (CTC) 的超灵敏检测和无损释放的新型细胞传感器。二维 Au@PdMo 纳米酶具有高效的类过氧化物酶活性，并与由硫醇修饰的上皮特异性细胞粘附分子 (EpCAM) 组成的适体组装以增强 CTC 粘附。此外，由于分形纳米结构与 CTCs 膜的相似性，电极表面用高分形金纳米结构 (HFAuNSs) 复合材料装饰，以提高 CTCs 的锚定效率和释放能力。通过电化学还原解吸，捕获的 CTC 可以进一步有效地从修饰电极上解离和无损释放。设计的细胞传感器显示出出色的分析性能，线性范围从 2 到 1 × 10^{5 个}细胞 mL ^-1和 2 个细胞 mL ^-1 (S/ N  = 3) 的检测下限 (LOD) 在 -0.6 至 0.2 V 范围内的工作电位。令人满意的 CTC 释放达到 93.7-97.4 的范围%，可接受的 RSD 为 3.55 至 6.41%，获得了良好的细胞活力。因此，开发的细胞传感器可能为进行基于 CTC 的液体活检提供潜在的替代方案，在肿瘤的早期诊断中具有广阔的应用前景。

图形概要