Date: Jul 30, 2014 Source: Forensic Magazine (
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The Denver Police Department Crime Laboratory, in collaboration with SomaLogic, Inc. (Boulder, Colorado), have developed a DNA aptamer-based system for sperm cell binding, isolation and purification for DNA analysis in sexual assault cases. The goal was to discover an inexpensive, rapid system for sperm cell capture that would be adaptable to forensic laboratory settings, particularly those with robotic workstations. The researchers identified a class of DNA aptamer molecules, called SOMAmers (slow off-rate modified aptamers), that bind specifically to sperm heads and tails and can bind to sperm under stringent or selective conditions.
Different solvents were tested for efficient sperm cell elution, using cotton swabs, the preferred method for collecting rape kit evidence. SOMAmer-coated magnetic beads, with Biotin and Streptavidin linkers, were used for sperm cell capture. SOMAmers demonstrated efficient sperm cell purification from eluates of sperm cells mixed with either HeLa cells or female buccal cells. Short tandem repeat DNA analysis showed clean male DNA profiles from captured and purified sperm cells. SOMAmer-based sperm cell separation, capture and purification more rapidly processes sexual assault evidence compared to other extraction methods and will help to reduce the backlog of DNA samples in forensic laboratories more quickly.
