Development and evaluation of a novel DNA purification buffer and protocol for blood samples on FTA cards

Abstract

DNA fingerprinting is expanding its horizons by the virtue of new innovative technologies. The use of FTA cards for the preservation of blood, saliva, and other biological samples is a preferred method, owing to the reliability and ease of sample preservation provided by this technology. Across the globe, FTA cards are routinely used in crime investigations to collect blood samples of victims, suspects and from the crime scene. Owing to lack of technical know-how, the FTA matrixes are often overloaded with blood samples as the collector tries to fill the entire circle(s) on the FTA card with blood. This makes purification of FTA punches unwieldy difficult with the standard FTA protocol. As a result, the FTA punches remain reddish in color, even after several washes. The purification process may hence take excess time, spanning to several hours. Further, FTA punches that are reddish in color have a bearing on multiplex PCR success rate as they may show no amplifications or partial amplifications. A new purification buffer reagent and a new protocol were designed to purify FTA punches rapidly. A comparative study revealed that the novel purification buffer and protocol successfully cleansed overloaded FTA cards in drastically less time as compared to the conventional buffer and protocol. Further, the success rate of multiplex PCR was high with the generation of complete STR profiles from all the samples.