Wang Congzhou, Stanciu Cristina E, Ehrhardt Christopher J, Yadavalli Vamsi K
Department of Chemical and Life Science Engineering, Virginia Commonwealth University, Richmond, VA, USA.
Department of Forensic Science, Virginia Commonwealth University, Richmond, VA, USA.
Forensic Sci Int. 2017 Aug;277:252-258. doi: 10.1016/j.forsciint.2017.06.019. Epub 2017 Jun 27.
Atomic force microscopy provides a novel morphological and physico-chemical perspective to analyze epithelial cell samples in forensic investigations. As a nanoscale, single cell tool, it allows the investigation of scarce samples in a non-destructive fashion. Using chemical force spectroscopy, it permits the identification of specific functional groups or surface molecules. Of specific interest is the presence of extracellular DNA (eDNA) on the surface of epithelial cells that line the exterior skin and interior cavities of human bodies, and can transfer onto surfaces through contact with skin and saliva. To date, this eDNA has only been measured a bulk level. Here, using nanoscale imaging, we first describe the unique differences between keratinized epithelial cells and non-keratinized buccal cells. Then via a force mapping technique, we show how eDNA can be spatially located and quantified on the cell surface. Our results suggest that presence and relative quantity of surface-associated, extracellular DNA signatures can be analyzed on individual epithelial cells from different tissue sources, providing a new tool in the forensic analysis of touch samples.
原子力显微镜为法医调查中分析上皮细胞样本提供了一种全新的形态学和物理化学视角。作为一种纳米级别的单细胞工具，它能够以非破坏性方式对稀缺样本进行研究。利用化学力谱技术，它可以识别特定的官能团或表面分子。特别值得关注的是，在人体外部皮肤和内部腔体的上皮细胞表面存在细胞外DNA（eDNA），并且它可以通过与皮肤和唾液接触转移到表面。迄今为止，这种eDNA仅在总体水平上进行过测量。在此，我们使用纳米级成像技术，首先描述角化上皮细胞和非角化颊细胞之间的独特差异。然后通过力映射技术，展示如何在细胞表面对eDNA进行空间定位和定量分析。我们的结果表明，可以对来自不同组织来源的单个上皮细胞上与表面相关的细胞外DNA特征的存在情况和相对数量进行分析，这为触摸样本的法医分析提供了一种新工具。
