A clinician first takes a fluid sample, such as blood or saliva from a patient, and injects it into the disposable straw within the device. A large cap on the device contains two small packets: a lysis buffer and an ethanol wash. Pressure from the pump releases the lysis buffer, which breaks open cells in the fluid, releasing DNA. A second pump of air releases ethanol, which washes out everything but the DNA.
So far, Klapperich has used the prototype to isolate DNA from nasal wash samples infected with influenza A. Compared with traditional DNA extraction kits in the laboratory, Klapperich says, the SNAP prototype isolates less DNA. “But in general, our data show that the nucleic acid we get back is cleaner,” she says. The DNA can also be amplified using the polymerase chain reaction, or PCR, one of the most common methods of amplifying DNA in the lab. In the near future, the group plans to experiment with other human fluids that contain different viruses; DNA from various bacteria and viruses may behave differently at room temperature.
Jose Gomez-Marquez, program director for the Innovations in International Health Initiative at MIT, first learned of Klapperich’s invention at a recent meeting about medical technology for the developing world. Since then, he and Klapperich have worked together to refine the prototype. Gomez-Marquez will soon be bringing a model to Nicaragua, where he hopes to get feedback on its effectiveness and user friendliness from local clinicians and patients. “This device doesn’t wait for a cold system to be in place for diagnostic samples to be transferred from one place to another,” says Gomez-Marquez. “You can take five days or two weeks to get a sample out there–you don’t have to worry about refrigerating it.”