Nanoscale Characterization of Forensically Relevant Epithelial Cells and Surface Associated Extracellular DNA

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 at bulk level. The results of the current study suggest that the 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. (Publisher abstract modified)