You Can Run, but Your DNA Can’t Hide

At Stanford University, a microfluidic chip has been developed that efficiently extracts sperm from rape kit samples. The chip’s channels, which are coated with Sialyl-LewisX, a carbohydrate ligand for sperm-egg binding, will capture a perpetrator’s sperm, but not a victim’s epithelial cells, which are easily washed away. After sperm are captured on the chip, they are lysed, and sperm DNA analysis commences. 

Television writers portray DNA evidence as a slam dunk, sealing the fate of many a villain in a fast-paced game of cat and mouse. The reality, however, is that a single DNA sample requires days to analyze, and many samples never get processed at all. DNA profiling has come a long way since its debut in 1986, but in many ways, it’s still in its infancy. Here are four ways researchers are breaking new ground with forensic uses of genetic analysis.

A DNA sample can indeed put a criminal behind bars or exonerate an innocent suspect – but only if it gets tested. If it stays in a neglected rape kit, for example, DNA won’t serve the cause of justice. Thousands of rape kits stay on shelves for years simply because each kit takes so long to process. The first big hold-up occurs when the rape kit’s sperm cells are separated from the victim’s own cells. This process, which requires multiple rounds of washing and centrifugation, can last eight hours.

“We can reduce that multistep process to a one-step process that takes just an hour,” says Utkan Demirci, Ph.D., professor of radiology at Stanford University. Dr. Demirci worked with Fatih Inci, a research scientist in his lab, to develop a microfluidic chip that grabs the sperm cells while allowing everything else to be washed away, all in one go.