Pinpointing pathogens

researchers have designed a chemical screening tool that will light up when dangerous pathogens and diseases in air, water and bodily fluids are present.

"This detection technique, which uses DNA to seek out target DNA, could one day be used in clinical care situations to quickly detect diseases such as AIDS and hepatitis," said Professor Ulrich Krull, the AstraZeneca Chair in biotechnology and vice-principal (research) at the University of Toronto at Mississauga. "It could also act to constantly monitor the environment and sound an alarm if harmful agents were to appear."

In a study, outlined in the March issue of Bioorganic & Medicinal Chemistry Letters, Krull and graduate student Xiaofeng Wang used a fluorescent dye to probe DNA that binds to specific target DNA sequences, illuminates in the presence of a targeted pathogen or genetic mutation and then sends a detection signal through an optical fibre.

By adding heat, the dye unbinds and the detection chemistry is ready to test the next sample. The chemical screening system fits onto a microchip and soon could test blood and water samples in a matter of seconds.

Krull said that while commercial development will still be needed to build a portable technology to facilitate this detection strategy, this research provides the basis for a re-usable, quick and compact sample testing system.

"The idea here is to have something like a thermometer that will monitor the environment and the body," he said. "But instead of temperature, you are monitoring for DNA fragments indicative of problems that can cause disease and infections. There are very few tests like this that allow for continuous monitoring."