Optimization and validation of a fully automated silica-coated magnetic beads purification technology in forensics

Automated procedures for forensic DNA analyses are essential not only for large-throughput sample preparation, but are also needed to avoid errors during routine sample preparation. The most critical stage in PCR-based forensic analysis is DNA isolation, which should yield as much highly purified DNA as possible. The extraction method used consists of pre-treatment of stains and samples, cell lysis using chaotropic reagents, binding of the DNA to silica-coated magnetic particles, followed by elution of the DNA. Our work focuses mainly on sample preparation, obtaining the maximum possible amount of biological material from forensic samples, and the following cell lysis, to create a simple standardized lysis protocol suitable for nearly all forensic material. After optimization and validation, the M-48 BioRobot((R)) workstation has been used for more than 20,000 routine lab samples. There has been no evidence of cross contamination. Resulting DNA from as small as three nuclear cells yield reliable complete STR amplification profiles. The DNA remains stable after 2 years of storage.