Monitoring trace circulating tumor cells (CTCs) in whole blood is important for early diagnosis and treatment of cancers. Whereas, it remains a major difficulty for detecting CTCs because of their extremely low contents in blood. Herein, by coupling biobarcode amplification method with sequence-responsive and enzyme-embedded DNA nanocapsules, we report a highly sensitive, label-free and specific electrochemical sensing assay to detect CTCs in blood. The target CTCs are selectively isolated from sample solutions by aptamer-conjugated magnetic beads and biobarcode DNA-functionalized polystyrene beads. Subsequent release of the biobarcode DNA can trigger the liberation of lots of enzymes from the nanocapsules, further leading to drastically enhanced catalytic current on the sensor electrode for detecting CTCs at the detection limit of 8 cell mL⁻¹ in a non-label approach. Moreover, whole blood-spiked target CTCs can also be detected by the developed strategy, offering it the great promise for the monitoring of different rare CTCs in complex samples for various biomedical applications.

监测全血中的痕量循环肿瘤细胞 (CTC) 对于癌症的早期诊断和治疗非常重要。然而，由于其在血液中的含量极低，因此检测 CTC 仍然是一个主要困难。在此，通过将生物条形码扩增方法与序列响应和酶包埋的 DNA 纳米胶囊相结合，我们报告了一种高灵敏度、无标记和特异性的电化学传感方法来检测血液中的 CTC。通过适体缀合的磁珠和生物条形码 DNA 功能化的聚苯乙烯珠从样品溶液中选择性地分离出目标 CTC。随后释放的 biobarcode DNA 可以触发大量酶从纳米胶囊中释放出来，进一步导致传感器电极上的催化电流显着增强，用于在 8 个细胞 mL 的检测限检测 CTC^-1在非标签方法中。此外，所开发的策略还可以检测全血加标靶 CTC，这为监测复杂样品中不同稀有 CTC 以用于各种生物医学应用提供了巨大的希望。