Development of an Integrated Automated System for Highly Efficient Isolation of DNA from a Range of Challenging Sample Inputs Including Bone

Abstract: Presented here are results validating a system in which a highly robust extraction chemistry was optimally adapted to a medium/high-throughput automated liquid handling and a DNA extraction/purification system capable of efficiently processing an unusually wide range of forensic sample types.  This system’s ability to execute liquid handling and extraction/purification steps in parallel substantially minimizes run times -- 96 samples can be processed on this system in approximately 80 mins.  In addition to performance on challenging bone, tooth and adhesive containing samples, also shown here is the ability of this combined system to effectively process frequently encountered case-type samples, particularly mock touch/trace samples.
In studies on challenging bone, tooth and adhesive-containing samples, this platform delivered comparable results to an established DNA purification instrument that has significantly less throughput capacity (13 samples per run versus 96 samples per run, with both systems employing offline lysis).  Repeatability and reproducibility over two independent experiments on this platform was good with a challenging bone sample, and good correlation to performance on the existing lower throughput platform was seen, with respect to DNA yields, and downstream STR profile quality and completeness.  Results, very consistent with the above-described findings, were also seen in additional experiments with tooth and adhesive-containing samples, as well as a wide range of mock touch/trace case-type samples.  As a test of the sensitivity of this system on a common body fluid / substrate pair, a sample set consisting of a dilution series of dried blood spotted on cotton swabs was processed.  Full STR profiles were consistently obtained with as little as 0.63 uL of blood input, and either full or almost full profiles were seen down to 0.16 uL blood input.  Importantly, over the diverse sample set examined in this validation study, including swabs of blood stains on denim, there was no indication of inhibitory factor carry-through in any of the eluates.
In summary, on a set consisting of 96 case-type sample lysates, the new system describe here is capable of delivering result highly comparable to those seen with a much lower throughput platform in significantly less time and with both input and output plasticware options, such as 96 well PCR plate output, that would be more convenient for many end-users in downstream processing steps.