In contrast to common DNA walkers, multipedal DNA walkers exhibit larger walking area and faster walking kinetics and provide increased amplification efficiency. Consequently, they have received a considerable amount of attention in biosensing. However, most of them are synthesized by immobilizing multiple DNA walking strands on the surface of Au nanoparticles, which is tedious and time-consuming. Simple preparation of multipedal DNA walkers remains a challenge. Herein, we adopted a simple enzyme-free target-triggered catalytic hairpin assembly (CHA) circuit to synthesize a tripedal DNA walker. By walking on a DNA track-functionalized electrode, a sensitive electrochemiluminescence DNA nanomachine biosensor was constructed for sensing miRNA-21. The DNA walker was powered by toehold-mediated strand displacement; the whole process did not need the assistance of enzymes, thus avoiding tedious procedures and enzyme degradation under unfavorable environmental conditions. Specifically, a superior detection limit of 4 aM and a broad linear range of 10 aM to 1 pM were achieved. This CHA–tripedal DNA walker biosensor was then applied for the detection of miRNA-21 in human serum and showed high selectivity and excellent reproducibility, demonstrating its practical application in bioanalysis. In particular, the Y-shaped tripedal DNA walker comes from the DNA circuit, which makes the approach ideally suited for biosensing of small nucleic acid targets.

中文翻译：

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由目标触发的催化发夹组装制备的简单三足 DNA Walker 用于 MicroRNA 的超灵敏电化学发光检测

与普通 DNA 步行器相比，多足 DNA 步行器具有更大的步行面积和更快的步行动力学，并提供更高的扩增效率。因此，它们在生物传感领域受到了相当多的关注。然而，它们中的大多数是通过将多条DNA行走链固定在Au纳米粒子表面来合成的，这既繁琐又耗时。多足 DNA 步行器的简单制备仍然是一个挑战。在这里，我们采用了一种简单的无酶靶触发催化发夹组装 (CHA) 电路来合成三足 DNA 步行器。通过在DNA轨迹功能化电极上行走，构建了一种灵敏的电化学发光DNA纳米机器生物传感器，用于传感miRNA-21。DNA walker 由立足点介导的链位移提供动力；整个过程不需要酶的辅助，从而避免了繁琐的程序和不利环境条件下的酶降解。具体而言，实现了 4 aM 的卓越检测限和 10 aM 至 1 pM 的宽线性范围。这种 CHA-tripedal DNA walker 生物传感器随后被应用于检测人血清中的 miRNA-21，并显示出高选择性和优异的重现性，证明了其在生物分析中的实际应用。特别是，Y 形三足 DNA walker 来自 DNA 回路，这使得该方法非常适合小核酸靶标的生物传感。实现了 4 aM 的卓越检测限和 10 aM 至 1 pM 的宽线性范围。这种 CHA-tripedal DNA walker 生物传感器随后被应用于检测人血清中的 miRNA-21，并显示出高选择性和优异的重现性，证明了其在生物分析中的实际应用。特别是，Y 形三足 DNA walker 来自 DNA 回路，这使得该方法非常适合小核酸靶标的生物传感。实现了 4 aM 的卓越检测限和 10 aM 至 1 pM 的宽线性范围。这种 CHA-tripedal DNA walker 生物传感器随后被应用于检测人血清中的 miRNA-21，并显示出高选择性和优异的重现性，证明了其在生物分析中的实际应用。特别是，Y 形三足 DNA walker 来自 DNA 回路，这使得该方法非常适合小核酸靶标的生物传感。