AbstractAn amperometric aptasensor is reported for the electrochemical determination of the epithelial cell adhesion molecule (EpCAM). It is based on a combination of EpCAM-driven toehold-mediated DNA recycling amplification, the specific recognition of EpCAM aptamer, and its binding to EpCAM. Hairpin probe 1 (Hp1) with a toehold region was modified with a 5′-thiol group (5’-SH) and self-assembled onto the surface of a gold electrode. Upon addition of EpCAM, the probe A (a 15-mer) is liberated from the aptamer/probe A complex and then hybridizes with the toehold domain of Hp1. This results in the exposure of another toehold for further hybridizing with hairpin probe 2 (Hp2) to displace probe A in the presence of Hp2 that was labeled with the electrochemical probe Methylene Blue (MB). Subsequently, liberated probe A is hybridized again with another Hp1 to start the next round of DNA recycling amplification by reusing probe A. This leads to the formation of plenty of MB-labeled DNA strands on the electrode surface and generates an amplified current. This 1:N probe-response amplification results in ultrasensitive and specific detection of EpCAM, with a 20 pg·mL−1 detection limit. The electrode is highly stable and regenerable. It was successfully applied to the determination of EpCAM in spiked human serum, urine and saliva, and thus provides a promising tool for early clinical diagnosis. Graphical abstractSchematic illustration of the electrochemical detection for EpCAM. The method is based on aptamer-based recognition and EpCAM-driven toehold-mediated DNA recycling amplification. Hp1: Hairpin probe 1; Hp2: Hairpin probe 2; MB: Methylene blue; MCH: 6-Mercapto-1-hexanol; EpCAM: Epithelial cell adhesion molecule.

中文翻译：

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通过使用目标驱动的立足点介导的 DNA 循环放大，用于上皮细胞粘附分子的超灵敏电流适体传感器

摘要报道了一种用于电化学测定上皮细胞粘附分子 (EpCAM) 的电流型适体传感器。它基于 EpCAM 驱动的立足点介导的 DNA 再循环扩增、EpCAM 适体的特异性识别及其与 EpCAM 的结合的组合。具有立足点区域的发夹探针 1 (Hp1) 用 5'-硫醇基团 (5'-SH) 修饰并自组装到金电极的表面。添加 EpCAM 后，探针 A（15 聚体）从适体/探针 A 复合体中释放出来，然后与 Hp1 的立足点结构域杂交。这导致在用电化学探针亚甲蓝 (MB) 标记的 Hp2 存在的情况下，暴露另一个立足点以与发夹探针 2 (Hp2) 进一步杂交以取代探针 A。随后，释放的探针A再次与另一个Hp1杂交，通过重复使用探针A开始下一轮DNA循环扩增。这导致在电极表面形成大量MB标记的DNA链并产生放大电流。这种 1:N 探针响应放大导致 EpCAM 的超灵敏和特异性检测，检测限为 20 pg·mL-1。电极高度稳定且可再生。它已成功应用于测定加标人血清、尿液和唾液中的 EpCAM，从而为早期临床诊断提供了有前景的工具。图形摘要 EpCAM 电化学检测的示意图。该方法基于基于适配体的识别和 EpCAM 驱动的立足点介导的 DNA 循环扩增。Hp1：发夹探针1；Hp2：发夹探针2；MB：亚甲蓝；MCH：6-巯基-1-己醇；EpCAM：上皮细胞粘附分子。