Circulating tumor cells (CTCs) are the important biomarker for cancer diagnosis and individualized treatment. However, due to the extreme rarity of CTCs (only 1–10 CTCs are found in every milliliter of peripheral blood) high sensitivity and selectivity are urgently needed for CTC detection. Here, a sandwich PEC cytosensor for the ultrasensitive detection of CTCs was developed using the photoactive material Au NP/-Fe₂O₃ and core-shell CdSe@CdS QD sensitizer. In the proposed protocol, the CdSe@CdS QD/Au NP/α-Fe₂O₃-sensitized structure with cascade band-edge levels could evidently promote the photoelectric conversion efficiency due to suitable light absorption and efficient electron-hole pair recombination inhibition. Additionally, a dendritic aptamer-DNA concatemer was constructed for highly efficient capture of MCF-7 cells carrying CdSe@CdS QDs, a sensitive material. The linear range of this proposed signal-on PEC sensing method was 300 cell mL⁻¹ to 6 × 10⁵ cell mL⁻¹ with a detection limit of 3 cell mL⁻¹, and it demonstrated an ultrasensitive response to CTCs. Furthermore, this PEC sensor enabled accurate detection of CTCs in serum samples. Hence, a promising strategy for CTC detection in clinical diagnosis was developed based on CdSe@CdS QD–sensitized Au NP/α-Fe₂O₃-based PEC cytosensor with dendritic aptamer-DNA concatemer.

Graphical abstract

中文翻译：

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CdSe@CdS 量子点敏化 Au/α-Fe2O3 结构用于循环肿瘤细胞的光电化学检测

循环肿瘤细胞 (CTC) 是癌症诊断和个体化治疗的重要生物标志物。然而，由于 CTC 极其稀有（每毫升外周血中仅发现 1-10 个 CTC），CTC 检测迫切需要高灵敏度和选择性。在这里，使用光敏材料 Au NP/-Fe ₂ O ₃和核-壳 CdSe@CdS QD 敏化剂开发了用于 CTC 超灵敏检测的夹层 PEC 细胞传感器。在拟议的协议中，CdSe@CdS QD/Au NP/α-Fe ₂ O ₃-具有级联带边能级的敏化结构由于适当的光吸收和有效的电子-空穴对复合抑制，可以显着提高光电转换效率。此外，还构建了树突状适体-DNA 串联体，用于高效捕获携带敏感材料 CdSe@CdS QD 的 MCF-7 细胞。这种建议的信号 PEC 传感方法的线性范围为 300 cell mL ^-1至 6 × 10 ⁵ cell mL ^-1，检测限为 3 cell mL ^-1, 它表现出对 CTC 的超灵敏反应。此外，该 PEC 传感器能够准确检测血清样本中的 CTC。因此，基于 CdSe@CdS QD 敏化的 Au NP/α-Fe ₂ O ₃基 PEC 细胞传感器和树突适体-DNA 多联体，开发了一种用于临床诊断中 CTC 检测的有前途的策略。

图形概要