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A Novel On-Chip Method for Differential Extraction of Sperm in Forensic Cases

NCJ Number
Advance Science Volume: 5 Issue: 9 Dated: June 2018
Date Published
June 2018
12 pages
Since current procedures for the differential extraction of victim's and perpetrator's cells in sexual assault cases is laborious and time-consuming, this report presents the methodology and findings of a project that developed a microfluidic method that selectively captures sperm using a unique oligosaccharide sequence (Sialyl-Lewis), a major carbohydrate ligand for sperm-egg binding.
The processing of evidence from sexual assault kits generally requires the separation of the victim's cells from the perpetrator's cells. The current process for doing this involves time-consuming, labor-intensive steps of selective cell lysis, centrifugation, and separation into female and male cell fractions. This can take up to 8 hours, which contributes significantly to the backlog of rape kits awaiting forensic analysis. In addition, a significant amount (60-90 percent) of male DNA may be lost during this procedure. The proposed improved method for the extraction of sperm in forensic cases involves a next-generation differential extraction technology that is, according to the authors, the most rapid, reliable, accurate, user-friendly method available. Although antibody-based capture approaches have been proposed for forensic samples, they are handicapped by loss of efficiency and specificity over time. The proposed method developed in this project integrates microfluidics with a unique oligosaccharide unit, a major binding ligand for egg and sperm interaction. By introducing bioinspired materials into a microfluidics realm, this project developed a powerful platform to selectively isolate sperm in heterogeneous matrices by performing only a few steps to provide on-chip sperm DNA lysate within 80 minutes.. It involves four sampling/washing steps and two incubation steps. All sampling and extraction steps can be performed by existing forensic DNA laboratory equipment and techniques. This method is still in development, however, so the expected improvements in design and workflow are outlined. 5 figures, 1 table, and 44 notes

Date Published: June 1, 2018