Johns Hopkins University, www.jhu.edu

Scientists at Johns Hopkins University have developed a test that uses quantum dots to find DNA attachments which are early warning signs of cancer. The test detects the presence and quantity of DNA changes, harbingers of cancer risk.

The test looks for DNA strands containing an abnormal methyl group by first converting strands with a methyl group into customized nucleotide strands. The strands are then combined with quantum dots, crystals of semiconductor material that measure only a few nanometers across. The dots are coated with a chemical that is attracted to the new strands. In experiments, up to 60 custom strands attached themselves to a single quantum dot. When a UV light or blue laser shines on this mixture, the dots off-load that energy — quantum dots have the inherent ability to easily and quickly transfer energy — to a particular molecule in each strand. The additional energy makes these molecules fluoresce, so researchers can identify and count them using a spectrophotometer. Researchers say because genetic markers for specific cancers differ, the test can be tweaked to look for different types of cancer. The test could be commercially available within five years, according to the scientists.