Glow shows individual DNA

Researchers from the University of Heidelberg in Germany and Florida State University have made a type of artificial DNA of that glows when it combines with a specific sequence of natural DNA.

In principle, the method could be used to develop DNA chips that directly sense individual DNA molecules, according to the researchers.

DNA is made from four types of bases -- adenine, cytosine, guanine, and thymine -- connected to a sugar-phosphate backbone. Double-stranded DNA forms when complementary bases in the two rows match and connect. A single strand of DNA can form a hairpin shape when matching segments along a single strand of DNA connect.

The researchers' used DNA strand that contains a fluorescent dye. It loses its glow when the molecule folds into a hairpin shape to bring the dye into contact with guanosine. When the DNA combines with another strand, for example, from a bacteria, the hairpin opens and exposes the fluorescent dye.

The researchers are working to develop DNA chips that can quickly detect small amounts of antibiotic-resistant bacteria. The method could also be used to detect other organisms as well.

The researchers are working on improving the detector's sensitivity.

The DNA sensor could be used in practical applications in two to five years, according to the researchers. The work appeared in the July 9, 2003 issue of Nano Letters.