Improved Molecular Beacons Show Promise for Cancer Detection, Rapid Viral Diagnosis

Believed to be the first technique for imaging RNA in living cells, a new class of beacons under development at the Georgia Institute of Technology and Emory University also has potential applications in the rapid diagnosis of viral infections, as well as drug discovery and pharmacogenomics. Their ability to rapidly detect viruses makes the beacons potentially valuable in the battle against bio-terrorism.
Georgia Tech and Emory researchers are developing improved signaling, targeting and delivery systems for the beacons, which consist of a fluorescent dye molecule and a quencher molecule at opposite ends of an oligonucleotide engineered to match specific genetic sequences associated with disease.
Initially, the dye and quencher molecules are held close together in a hairpin shape, the quencher preventing fluorescent emission from the dye. When delivered into cells, the beacons seek out matching sequences in genetic material known as messenger RNA (mRNA). If the beacons encounter and bind with their specific mRNA targets, Watson-Crick base-pairs holding the dye and quencher together break, allowing emission of a specific fluorescent signal when excited by light.
Details of the research, sponsored by the Wallace H. Coulter Foundation and the National Science Foundation, were presented March 26 at the 225th American Chemical Society National Meeting in New Orleans, LA.
Researchers led by Gang Bao, associate professor in the Wallace H. Coulter Department of Biomedical Engineering operated jointly by Georgia Tech and Emory, are improving earlier beacon systems to overcome problems specific to their use in living cells. They have also made progress developing magnetic beacons suitable for use in body tissues too deep for optical imaging to work.