Herein, an orbitron-like three-dimensional (3D) DNA clip-based nanomachine was proposed for ultrasensitive fluorescent bioassay of microRNA, which was constructed by mechanically interlocking double-DNA-ring with two single-stranded DNAs, performing an orbitron-like 3D structure with double freely rotated DNA rings as the open state. In the presence of target microRNA, the proposed orbitron-like 3D DNA clip can alter its structure from open to closed state in identification of the target microRNA, generating the closure between the previously modified fluorescent dyes and the quenchers to perform a "signal off" fluorescent signal correlated with the concentration of target microRNA. Compared with the normal DNA nanomachines, such as DNA tweezers constructed by self-assembly of three single-stranded DNAs which regulated the open and closed states on the basis of linear conformational changes, the proposed 3D DNA clip-based nanomachine with high mechanical rigidity realized the conformational changes in 3D space with the assistance of target microRNA, which could effectively increase the adjustable distance range and reduce the background signal. Furthermore, the 3D DNA clip-based nanomachine was applied in the fluorescent detection of microRNA-21 with favorable performances for the sensitive detection of microRNA in cells, providing a new avenue for early clinical diagnoses of disease.

中文翻译：

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基于轨道器的 3D DNA Clip 纳米机器及其在 MicroRNA 灵敏荧光生物测定中的应用

在此，提出了一种基于轨道加速器的三维 (3D) DNA 夹子纳米机器，用于 microRNA 的超灵敏荧光生物测定，它是通过机械互锁双 DNA 环与两个单链 DNA 构建的，执行类似轨道加速器的 3D双自由旋转的 DNA 环作为开放状态的结构。在目标 microRNA 存在的情况下，拟议的类轨道器 3D DNA 剪辑可以在识别目标 microRNA 时将其结构从开放状态改变为关闭状态，从而在先前修饰的荧光染料和猝灭剂之间产生闭合以执行“信号关闭”荧光信号与目标 microRNA 的浓度相关。与普通的DNA纳米机器相比，例如由三个单链 DNA 自组装构建的 DNA 镊子，在线性构象变化的基础上调节打开和关闭状态，提出的具有高机械刚度的基于 3D DNA 夹的纳米机器实现了 3D 空间的构象变化目标microRNA的辅助，可有效增加可调距离范围，降低背景信号。此外，基于3D DNA夹子的纳米机器应用于microRNA-21的荧光检测，对细胞中microRNA的灵敏检测具有良好的性能，为疾病的早期临床诊断提供了新的途径。所提出的具有高机械刚度的基于 3D DNA 夹的纳米机器在目标 microRNA 的帮助下实现了 3D 空间的构象变化，可以有效地增加可调距离范围并减少背景信号。此外，基于3D DNA夹子的纳米机器应用于microRNA-21的荧光检测，对细胞中microRNA的灵敏检测具有良好的性能，为疾病的早期临床诊断提供了新的途径。所提出的具有高机械刚度的基于 3D DNA 夹的纳米机器在目标 microRNA 的帮助下实现了 3D 空间的构象变化，可以有效地增加可调距离范围并减少背景信号。此外，基于3D DNA夹子的纳米机器应用于microRNA-21的荧光检测，对细胞中microRNA的灵敏检测具有良好的性能，为疾病的早期临床诊断提供了新的途径。