The detection of a small number of exosomes provides the possibility for early cancer diagnosis and prognosis. Here, a multi-signal amplified electrochemical sensing platform was explored for the ultrasensitive detection of tumor exosomes relying on catalytic hairpin assembly-triggered DNA walker, entropy beacon-based DNA assembly and Ag@C core-shell nanocomposites. In this work, the utilization of Ag@C nanocomposites as electrode interface effectively enhanced functional active sites and electron transfer capability. By designing a target-assisted entropy beacon-based DNA assembly, single exosome initiated the release of multiple special DNA sequences, which could be separated conveniently by magnet and then hybridize with the blocking DNA to liberate swing arm. DNA walker was activated with the assistance of catalytic hairpin assembly, introducing extensive electroactive methylene blue (MB) to electrode surface. Thus, the detection of exosomes was transferred into the measurement of the MB current, with a good liner range from 100 to 75 000 particles/μL. Furthermore, this constructed sensing system displayed acceptable reproducibility, long-term stability, favorable selectivity, and highlighting application potential in real samples.

中文翻译：

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用于电化学传感用 Ag@C 核壳纳米复合材料致敏的肿瘤外泌体的催化发夹组装触发的 DNA walker

少量外泌体的检测为早期癌症诊断和预后提供了可能。在这里，基于催化发夹组装触发的 DNA walker、基于熵信标的 DNA 组装和 Ag@C 核壳纳米复合材料，探索了一种多信号放大电化学传感平台，用于肿瘤外泌体的超灵敏检测。在这项工作中，利用 Ag@C 纳米复合材料作为电极界面有效地增强了功能活性位点和电子转移能力。通过设计基于靶标辅助熵信标的 DNA 组装，单个外泌体启动多个特殊 DNA 序列的释放，这些序列可以方便地被磁铁分离，然后与阻断 DNA 杂交以释放摆臂。DNA walker 在催化发夹组装的帮助下被激活，在电极表面引入大量的电活性亚甲蓝（MB）。因此，外泌体的检测被转移到 MB 电流的测量中，具有 100 到 75 000 个粒子/μL 的良好线性范围。此外，这种构建的传感系统显示出可接受的重现性、长期稳定性、良好的选择性，并突出了在实际样品中的应用潜力。