A combined method to locate and improve DNA recovery from fabrics

Abstract

The purpose of this thesis project is to identify touch DNA on different clothing surfaces and improve DNA recovery and efficiency. This study undertook a multi-method approach to improve identify touch DNA on clothing and enhance recovery rates. The approach was initiated after Vacuum Metal Deposition (VMD) processing to visualize the location of DNA on the fabric's surface. The multi-method approach involved comparing wet-swab and M-Vac® techniques for DNA collection, evaluating silica-membrane-based (QIAmp™) and magnetic silica-based (DNA IQ™) DNA extraction methods, and gauging the efficacy of size exclusion chromatography in eliminating metal ions from VMD-processed DNA samples. Nine fabrics with duplicates, eighteen in total, were collected for processing. Dark colored fabrics were processed with silver and zinc, and the light-colored fabric samples were processed with gold and zinc. After collection, each sample fabric type had quadruplicates for statistical analysis. Results indicated that the multi-method approach did not apply a statistically significant effect on the concentration of DNA in a sample. The multi-method approach did apply a statistically significant effect on the number of allele peaks present in an electropherogram (p<0.05). QIAmp™, no size exclusion chromatography performed, and M-Vac® collection samples performed better than their respective counterparts in the general linear mixed effect model. A technique that employs the M-Vac® wet vacuum for gathering touch DNA samples, followed by DNA extraction utilizing the QIAmp™ kit, and bypasses size exclusion chromatography, can offer more detailed genetic profiles.