This paper presents the first scanning electron microscopy (SEM)‐based DNA imaging in biological samples. This novel approach incorporates a metal‐free electro‐stain reagent, formulated by combining DNA‐binding proteins and synthetic polymers to enhance the visibility of 2‐nm‐thick DNA under SEM. Notably, DNA molecules stain with proteins and polymers appear as dark lines under SEM. The resulting DNA images exhibit a thickness of 15.0±4.0 nm. As SEM is the primary platform, it integrates seamlessly with various chemically functionalized large surfaces with the aid of microfluidic devices. The approach allows high‐resolution imaging of various DNA structures including linear, circular, single‐stranded DNA and RNA, originating from nuclear and mitochondrial genomes. Furthermore, quantum dots are successfully visualized as bright labels that are sequence‐specifically incorporated into DNA molecules, which highlights the potential for SEM‐based optical DNA mapping. In conclusion, DNA imaging using SEM with the novel electro‐stain offers electron microscopic resolution with the ease of optical microscopy.

中文翻译：

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使用由 DNA 结合蛋白和合成聚合物组成的无金属电染色剂对大 DNA 分子进行扫描电子显微镜成像

本文首次展示了生物样品中基于扫描电子显微镜 (SEM) 的 DNA 成像。这种新颖的方法采用了一种无金属电染色试剂，该试剂由 DNA 结合蛋白和合成聚合物组合而成，可增强 SEM 下 2 纳米厚 DNA 的可见度。值得注意的是，用蛋白质和聚合物染色的 DNA 分子在 SEM 下显示为黑线。所得 DNA 图像的厚度为 15.0±4.0 nm。由于 SEM 是主要平台，因此它借助微流体装置与各种化学功能化的大表面无缝集成。该方法可以对源自核和线粒体基因组的各种 DNA 结构进行高分辨率成像，包括线性、环状、单链 DNA 和 RNA。此外，量子点成功地被可视化为明亮的标签，可以序列特异性地整合到 DNA 分子中，这凸显了基于 SEM 的光学 DNA 作图的潜力。总之，使用 SEM 和新型静电染色进行 DNA 成像可提供电子显微镜分辨率，并且易于使用光学显微镜。