Forensic laboratories worldwide are under continuous pressure to process DNA evidence from sexual assault investigations, often surpassing their current throughput capabilities. Sexual assault samples, collected from bodily fluids, tissues, clothing, and other materials, typically contain a mix of cells from both the alleged perpetrator and the victim. Additionally, DNA in these samples may be degraded or present in low concentrations, complicating the process of obtaining a clear DNA profile for individualization.
The predominant method for analyzing sexual assault samples involves separating sperm cells from all other cell types present. Most current protocols for isolating sperm cells rely on the differential chemical lysis of epithelial cells from the victim, followed by manual centrifugation and washing steps. This process separates DNA from non-sperm cells, mainly of female origin, from any sperm cells. However, this technique is lengthy, labor-intensive, and challenging to automate. In response, alternative methods like automation have been developed to assist in processing sexual assault samples.
This App Note highlights Aurora VERSA1100 aimed at improving or complementing Differential Digestion extraction (DD)—the process that separates spermatozoa from non-sperm cells in forensic mixtures. While not exhaustive, this paper focuses on key developments that leverage unique chemistries and physics at the microscale level. For full results and details please read the Application Note.