Detection and str analysis of dna degradation in swab samples taken from bloody surfaces treated with different detergents

Except for identical twins, all humans have different DNA. Following the acceptance of DNA as an identification material in forensic sciences, DNA has gained an indispensable place in this field thanks to the discovery of Polymerase Chain Reaction and Short Repetitive Sequence analysis based on the analysis of specific polymorphic regions. DNA profiles can be obtained by analyzing any biological sample containing human cells. The most reliable and healthiest results are seen in the profiles obtained as a result of the analysis of blood samples. In this thesis, it is aimed to determine whether a possible degradation of DNA occurs by applying some detergents at different concentrations and at different time periods on blood samples. In this study, different concentrations of concentrated bleach, surface cleaner, dishwashing detergent, Sodium Dodecyl Sulfate and Triton X-100 were applied on blood samples dripped/spread on 10*10 cm sized tile pieces. Time periods of 30, 60, 90 and 120 min were selected as time periods. Biological swab sapmles were then taken from the surface of the tiles by passing through tap water. DNA isolation was performed on the samples taken respectively. Real-Time Polymerase Chain Reaction Quantification method was used to determine the amount of DNA in the isolates obtained. After the determined values, Polymerase Chain Reaction was performed on the isolates and amplicons were obtained. Capillary Electrophoresis Method was applied to the obtained amplicons. Following the completion of the process, the results were analyzed and DNA profiles were obtained. As a result of the analysis of DNA profiles, it was concluded that different concentrations of bleach, dishwashing detergent, surface cleaner, Sodium Dodecyl Sulfate and Triton X-100 detergents could not completely degrade DNA in the blood samples. It was determined that the amount of DNA partially decreased as the detergent concentration value increased, but sufficient DNA profiles were obtained for identification.