A rotational platform-driven microdevice for differential separation, purification, & amplification of sexual assault forensic samples

As submitted by the proposer: Some of the most common types of cases received in a forensic DNA laboratory are those involving sexual assault/battery, rape, or attempted rape. Often, the biological evidence collected for these cases includes a physical evidence recovery kit, or “rape” kit. Samples collected in the kits vary and depend on the victim’s recounting of the assault, but often include skin and cavity swabs of areas of penetration/ejaculation (ie. vaginal swabs, anal swabs, etc.); these swabs are likely to include sperm cells (from a male suspect) as well as cells from the victim. Luckily, procedures designed to separate sperm cells from all non-sperm cells (primarily the victim’s epithelial cells) prior to cell lysis and DNA extraction exist. Differential lysis procedures greatly reduce the presence of mixtures (or of secondary contributors) in these samples but are difficult to automate and most often require time-intensive hands-on processes that are not 100% efficient in separating the two cellular components of the mixture. Microdevices may offer an alternative to manual analytical procedures circumventing these issues. However, most researchers interested in microdevice development are focused on ìTAS – complete integration of laboratory workflow in a single microdevice (ie. “lab-on-a-chip”), which is currently many years away from implementation for forensic sample processing. Thus, this research group has shifted towards making more immediate use of microdevice advancements for replacing only a portion of the total workflow. This approach would improve processing time, minimize variability associated with manual procedures, and shift manual labor to the traditional downstream processes that require examiner time and extensive training (CE analysis, profile interpretation and reporting). The approach described in this proposal offers a simple, inexpensive microdevice that utilizes recently developed modules and microfluidic control strategies to replace some of the most laborious steps of sample processing for sexual assault swabs. This approach integrates two existing, recently developed on-chip modules (for DNA preparation & IR-mediated PCR) and an existing rotational platform for microfluidic control (1,2) with a novel upstream module for and antibody-based differential separation of sperm and non-sperm cells (to be developed). If funded, this microdevice could be available for testing, commercialization, and technology transfer within a two year window and could be easily validated/implemented by operational forensic DNA laboratories as this system would replace only upstream analytical wet-lab steps (through amplification), providing a DNA sample (for storage) and amplified STR products available for off-line, unaltered traditional quantitation and amplicon separation/detection via capillary electrophoresis. Note: This project contains a research and/or development component, as defined in applicable law. ca/ncf