Published January 1, 2018 | Version v1
Journal article Open

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

  • 1. Stanford Univ, Stanford Sch Med, Canary Ctr Stanford Canc Early Detect, Dept Radiol,Bioacoust MEMS Med BAMM Lab, Palo Alto, CA 94304 USA
  • 2. Harvard Med Sch, Brigham & Womens Hosp, Dept Med, Boston, MA 02115 USA
  • 3. Stanford Univ, Stanford Genome Technol Ctr, Dept Biochem, Palo Alto, CA 94304 USA
  • 4. Broward Cty Sheriffs Off, Crime Lab, Ft Lauderdale, FL 33301 USA
  • 5. DxNow Inc, Gaithersburg, MD 20879 USA

Description

One out of every six American women has been the victim of a sexual assault in their lifetime. However, the DNA casework backlog continues to increase outpacing the nation's capacity since DNA evidence processing in sexual assault casework remains a bottleneck due to laborious and time-consuming differential extraction of victim's and perpetrator's cells. Additionally, a significant amount (60-90%) of male DNA evidence may be lost with existing procedures. Here, a microfluidic method is developed that selectively captures sperm using a unique oligosaccharide sequence (Sialyl-Lewis(X)), a major carbohydrate ligand for sperm-egg binding. This method is validated with forensic mock samples dating back to 2003, resulting in 70-92% sperm capture efficiency and a 60-92% reduction in epithelial fraction. Captured sperm are then lysed on-chip and sperm DNA is isolated. This method reduces assay-time from 8 h to 80 min, providing an inexpensive alternative to current differential extraction techniques, accelerating identification of suspects and advancing public safety.

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