Abstract We developed a novel dual-amplification strategy for sensitive electrochemical detection of amyloid β oligomers (AβO) based on exonuclease III-assisted DNA recycling and rolling circle amplification (RCA). In this assay, gold electrode was used to immobilize molecular beacon (H2) with a 3′ overhang as recognition probes and perform the dual signal amplification procedure. In the presence of AβO, the AβO binding aptamer (H1) preferred to form AβO/H1 complex, making the region II of H1 hybridized with specifically designed capture H2 to form a double-stranded structure and created a 3′-blunt end for Exo III to initiate the DNA recycling amplification process to cleave numerous H2 probes. Then, the remaining H2 fragments hybridized as primers with the RCA template to initiate the RCA process. Consequently, hemin stacked into the G-quadruplex forming region, and the hemin/G-quadruplex was formed, generating an amplified electrochemical signal by differential pulse voltammetry. This novel signal amplification strategy could detect target AβO down to 39 fmol L−1, with a dynamic range spanning five orders of magnitude. Moreover, the approach is free of any label conjugation step and thus has great potential for the development of robust aptasensors.

中文翻译：

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基于双扩增诱导血红素/G-四链体形成的淀粉样蛋白β寡聚体的信号开启和无标记电化学检测

摘要 我们开发了一种新的双扩增策略，用于基于外切核酸酶 III 辅助的 DNA 循环和滚环扩增 (RCA) 的淀粉样蛋白 β 寡聚体 (AβO) 的灵敏电化学检测。在该测定中，金电极用于固定具有 3' 突出端的分子信标 (H2) 作为识别探针并执行双信号放大程序。在 AβO 存在下，AβO 结合适体 (H1) 优先形成 AβO/H1 复合物，使 H1 的 II 区与专门设计的捕获 H2 杂交形成双链结构，并为 Exo 创造了 3'-钝端III 启动 DNA 循环扩增过程以切割大量 H2 探针。然后，剩余的 H2 片段作为引物与 RCA 模板杂交以启动 RCA 过程。最后，氯化血红素堆叠到 G-四链体形成区域，并形成氯化血红素/G-四链体，通过差分脉冲伏安法产生放大的电化学信号。这种新颖的信号放大策略可以检测低至 39 fmol L-1 的目标 AβO，动态范围跨越五个数量级。此外，该方法没有任何标记缀合步骤，因此具有开发稳健适体传感器的巨大潜力。