การเพิ่มปริมาณดีเอ็นเอที่เกิดจากการสัมผัสบนหลักฐานระเบิดแสวงเครื่องด้วยเทคนิคไดเร็คพีซีอาร์

Abstract

STR profiling from improvised explosive device (IED) evidence results in low success rates due to trace amount of DNA available and DNA degradation. Moreover, 30-70 percent of DNA is lost during extraction process. To overcome these problems, direct PCR, which omits the DNA extraction process, can be used to increase the efficiency and success rates of STR typing from trace biological evidences. In this study, we developed a direct PCR protocol combined with optimal collection methods for touch DNA analysis from IED evidence. The result showed that direct amplification protocol successfully amplified touch DNA on all IED substrates. However, the optimal touch DNA collection method depended on substrate types. Cotton swab with phosphate buffer saline (PBS) was most suitable for non-absorbent substrates and electrical tape (3M tape), while tapelifting was most suitable for absorbent substrates. Identifiler® Plus kit had higher efficiency compared to IDplex® Plus kit in amplifying touch DNA by direct protocol. Furthermore, the developed process provided higher STR profiling success rates, which was 1.6 times higher for donor alleles compared to the conventional process. The developed method could be beneficial for the Central Institute of Forensic Science, Police Forensic Science Centers, and forensic-related institutes worldwide.