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Closed System DNA Purification for Degraded, Compromised Evidence in Microfluidic Devices

NCJ Number
Date Published
January 2012
53 pages
This project demonstrates that volume reduction solid phase extraction (vrSPE) technology is a successful method for processing a wide variety of large volume, degraded, inhibited biological samples in a timely manner that is free of cross-contamination.
Acquiring a DNA profile from large-volume, highly degraded or compromised forensic samples is challenging when interfaced with a microfluidic system. Previous microfluidic devices that use a silica-based solid phase have successfully purified DNA from complex biological samples such as whole blood; however, due to their small cross-sectional areas, they cannot operate at sufficiently fast flow rates to make the processing of mL volumes a feasible option. This project developed a volume-reduction, solid-phase extraction (vrSPE) device that uses a large cross-sectional area, enabling flow rates capable of handling a 0.5 mL in a 30-minute cycle. The vrSPE device was used to purify degraded whole blood and semen stains that were exposed to a maximum of 80 degrees C for 3 months or subjected to UV light for the equivalent of 8 months and 16 days in sunlight. Full STR profiles resulted in each instance. The extraction of bone was also demonstrated. The vrSPE device also successfully purified and extracted amplifiable mtDNA from a severely heat-degraded whole blood stain. The addition of a downstream uSPE phase, using chitosan-coated silica particles that provided completely aqueous chemistry, further enhanced the removal of indigo dye, a common sample contaminant in blue jeans. STR profiles produced with the dual-phase device were superior to those from the vrSPE channel alone. This achieves further removal of inhibitory material and increased concentration of the sample, which is especially resonant with severely diluted samples. The fabrication of devices in either a multi-channel or multiplex format were devised. Poly (methyl methacrylate) PMMA was selected as the new substrate for these devices. A detailed technical description is provided. 27 figures, 22 references, and a listing of 29 sources that have disseminate reports on this project

Date Published: January 1, 2012