Date of Graduation
Eberly College of Arts and Sciences
Forensic and Investigative Science
Sexual Assault Kits (SAKs) account for a large portion of DNA mixture samples that are processed within a forensic laboratory, most commonly in the form of vaginal swabs. A typical vaginal swab from a SAK contains the female victim's epithelial cells and varying concentrations of sperm cells left by the perpetrator. The key to analyzing these types of samples is to separate the mixture into male and female fractions. As such, there is a demand to develop novel techniques that have the capability of recovering as much of the male fraction as possible, specifically in cases where there is a limited sperm concentration to begin with. Magnetic beads are a versatile product in that they can be coupled with a variety of substances including a silica coating or various antibodies. Several studies have explored techniques to target testis specific molecules to isolate sperm from DNA mixtures. This study targeted a protein (PH-20) that is not testis specific but is intrinsic to the head of a sperm cell.
The goal was to evaluate the efficiency of magnetic beads coupled with anti-PH-20 antibodies in isolating sperm cells from DNA mixtures. Results suggested that streptavidin (SA) coated immunomagnetic beads (IMBs) recover more male DNA than carboxylic acid coated IMBs in both male-only samples and male:female mixture samples. Overall, the SAIMBs recovered approximately 21.7% of the total male DNA available in samples. While more research is needed to optimize the recovery of male DNA utilizing the IMB process, magnetic beads coupled with PH-20 antibodies have shown success in recovering male DNA and have considerable potential for forensic applications.
Becks, Kayla, "Immunomagnetic Beads Coupled with Anti-PH-20 Antibodies to Isolate Sperm from DNA Mixtures for Sexual Assault Kit Application" (2019). Graduate Theses, Dissertations, and Problem Reports. 7410.