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Abstract：
Nanoscale analysis of extracellular DNA (eDNA) that is present on the surface of cells in trace biological samples can provide insight into the understanding of DNA transfer through touch, and thereby, the role of eDNA is a biologically and forensically relevant phenomenon. While various bulk scale tools and DNA analysis can be used to quantitatively obtain this information, obtaining a three dimensional (3D) visualization of the eDNA can provide a unique look into the spatial and temporal dynamics at the cellular level. In this study, we show how atomic force microscopy (AFM) can be integrated with optical microscopy to visualize the distribution of surface associate eDNA at a single cell level. Using a nucleic acid fluorophore such as Diamond™ Dye, the surface eDNA can be observed and quantified using fluorescence microscopy. This informational channel can then be overlaid with surface topography and cellular elasticity to provide structural visualization. Finally, chemical force spectroscopy can be used to obtain the distribution of surface-associated eDNA on the cell surface at the molecular level. Such integrated techniques can enhance understanding of the biological role of eDNA, and can also be potentially valuable for investigating challenging trace samples, containing very few cells for various analyses.
摘要：
对痕量生物样品中存在于细胞表面的细胞外DNA（eDNA）进行纳米级分析，可以通过触摸深入了解DNA转移，因此，eDNA的作用是生物学和法医相关的现象。虽然可以使用各种批量缩放工具和DNA分析来定量获得这些信息，获得eDNA的三维(3D)可视化可以提供对细胞水平的空间和时间动态的独特观察。在这项研究中,我们展示了原子力显微镜（AFM）如何与光学显微镜集成在一起，以在单细胞水平上可视化表面缔合eDNA的分布。使用诸如Diamond™Dye的核酸荧光团，可以使用荧光显微镜观察和定量表面eDNA。然后可以用表面形貌和细胞弹性覆盖该信息通道以提供结构可视化。最后,化学力光谱法可用于在分子水平上获得表面缔合的eDNA在细胞表面的分布。这种集成技术可以增强对eDNA生物学作用的理解，也可能对调查具有挑战性的痕量样本有潜在价值，包含很少的细胞进行各种分析。
