Thursday, March 08, 2012

#MEDICAL: "Personal DNA Testing Made Easy"

University of Illinois chemists coupled functional DNA sensors and glucose meters for fast, easy, portable detection of drugs, toxins, disease markers and other molecules in blood, water or food.

Today DNA tests are performed in the laboratory to detect all sorts of toxins, diseases, drugs and other substances-of-interest. However, chemists now want to allow unskilled personnel to perform those tests at home, potentially enabling anybody to identify which flu-virus, bacterial infection or drug is in their bloodstream.

Personal glucose meters are routinely used by millions of diabetics today who take a small sample of blood from which the meter counts the number of glucose molecules. University of Illinois chemists maintain that by adding a testing liquid that is known to bind to the pathogen DNA, the glucose meter can be persuaded to count the number of pathogen molecules present in the blood, serum, water, or food sample.

As a home DNA detector, the ubiquitous glucose meter could become a general purpose detector that not only determines which type of virus or bacteria is in your bodily fluids or foods, but also quantifies the seriousness of the infection by revealing how much is present.

The device is the brainchild of chemistry professor Yi Lu, and postdoctoral researcher Yu Xiang, both at the University of Ill. The group proposes creating a whole array of low-cost test kits for use by the public for the early diagnosis of diseases, infections, and contaminants in foods. The technique could be especially useful in remote areas without local laboratory facilities, and will also be much less expensive than standard lab tests.

The system works by placing a sample of blood, serum, water, or food into a sugar-water solution of sucrose combined with the binding substance for a specific test--say for flu virus or food bacteria. If the virus or bacteria is present in the sample, then it will bind causing the sucrose to be converted into glucose.

The binding substance is itself a fragment of DNA that matches the virus or bacteria being detected, but with the addition of an enzyme (called invertase) which converts the sucrose in the solution into glucose. Because the amount of glucose converted is in exact proportion to the level of contamination, the glucose meter becomes a quantitative DNA detector capable of measuring the seriousness of an infection.

To prove the concept, the researchers detected the hepatitis virus is the blood of known carriers, giving almost instant measurements that were as accurate as laboratory tests that take a day more to perform at a much higher cost.
Funding was provided by the U.S. Department of Energy, the National Institutes of Health and the National Science Foundation.