A surface-enhanced Raman scattering (SERS) method is proposed for the assay of microRNA 122 based on configuration change of DNA tetrahedron. Firstly, a DNA tetrahedron was self-assembled with one vertex labeled with toluidine blue (TB). Then, it was immobilized on the porous Ni/SiO2@PEI@Au as a SERS platform, which was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). At this time, the DNA tetrahedron was contracted; so, the TB is close to AuNPs and the Raman signal is high. When target microRNA 122 existed, with the nicking enzyme amplification strategy, a great deal of DNA signal chains (S5) was obtained, which can extend the contracted DNA tetrahedron and change it into a three-dimensional DNA tetrahedron. In this case, the TB was far from AuNPs, resulting in a lower Raman signal. Due to the configuration change of DNA tetrahedron, the Raman signal at 1624 cm−1 (with the excitation wavelength of 633 nm) has a linear relationship with the logarithm concentration of microRNA 122. This SERS assay has high sensitivity for microRNA 122 with a determination range from 0.01 aM to 10 fM and a detection limit of 0.009 aM. The recoveries from spiked samples were in the range 95 to 109%. This SERS strategy is designed based on the target-triggered configuration change of DNA tetrahedron, which can give new insight for DNA structures in bioanalysis. Graphical abstract A sensitive surface-enhanced Raman scattering (SERS) biosensor was developed to detect microRNA 122 using the configuration change of DNA tetrahedron to indirectly control the position of TB and hot spot. A sensitive surface-enhanced Raman scattering (SERS) biosensor was developed to detect microRNA 122 using the configuration change of DNA tetrahedron to indirectly control the position of TB and hot spot.

中文翻译：

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用于 microRNA 122 的 SERS 测定的 DNA 四面体的目标触发构型变化

提出了一种基于 DNA 四面体构型变化的表面增强拉曼散射 (SERS) 方法来检测 microRNA 122。首先，一个 DNA 四面体与一个用甲苯胺蓝 (TB) 标记的顶点自组装。然后，将其固定在多孔 Ni/SiO2@PEI@Au 上作为 SERS 平台，通过扫描电子显微镜 (SEM) 和 X 射线衍射 (XRD) 对其进行表征。此时，DNA四面体收缩；因此，TB 接近 AuNP，拉曼信号很高。当目标microRNA 122存在时，利用切口酶扩增策略，获得大量DNA信号链（S5），可以将收缩的DNA四面体延伸，变成三维DNA四面体。在这种情况下，TB 远离 AuNP，导致拉曼信号较低。由于DNA四面体的构型变化，1624 cm-1（激发波长为633 nm）的拉曼信号与microRNA 122的对数浓度呈线性关系。该SERS检测对microRNA 122具有高灵敏度，具有测定范围从 0.01 aM 到 10 fM，检测限为 0.009 aM。加标样品的回收率在 95% 到 109% 之间。这种 SERS 策略是基于目标触发的 DNA 四面体构型变化而设计的，可以为生物分析中的 DNA 结构提供新的见解。图形摘要 开发了一种灵敏的表面增强拉曼散射 (SERS) 生物传感器来检测 microRNA 122，利用 DNA 四面体的构型变化间接控制 TB 和热点的位置。