The quest to improve DNA extraction efficiency: cellular adhesion to cotton fabric
Speidel, Sylvia Grace
MetadataShow full item record
When there is a possibility of a low-template sample being processed in a forensic laboratory, it becomes important to retrieve all cells possible from the substrate they are collected on. The most common form of evidence received by forensic laboratories is epithelial cells collected on cotton material, swab or fabric, which may contain inhibitors. Data shows a likely mechanism for cellular adherence is the denaturation of surface proteins to expose residues hidden within. Proteins on cotton’s cell surface hydrogen bond to these residues, forming a strong attachment. An epithelial cell preparation was pipetted onto ISO adjacent cotton swatches. These swatches were incubated in 10mM Tris, 0.1 mM EDTA (TE) buffer with a constant temperature and agitation from a Thermal Mixer. The swatch was removed from the liquid and placed in a separate tube and digest separately. Each was quantified and used to calculate the percentage of cellular release. Variations of this baseline procedure were used to help determine the most efficient cellular release process. These variables included different temperatures and agitation speeds, sonication, resuspension and the addition of disaccharides. Results showed that the addition of a disaccharide is the most efficient method to achieve cellular release from cotton fabric. Specifically, drying 0.75 M D-(+)- Trehalose Dihydrate onto a cotton fabric swatch before the addition of the epithelial cell preparation. This procedure produced an average of 65.5% cellular release compared to a 26.0% release from our baseline procedure.