Molecular Beacons Show Promise for Cancer Detection

The researchers presented a summary of their work at the national meeting of the American Chemical Society in New Orleans (LA, USA).

The beacons consist of a fluorescent dye molecule and a quencher molecule on 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 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.

In the future, scientists may introduce these molecular beacons into the body and then watch for specific optical or magnetic signals as the nanometer-scale structures latch onto their targets. So far, the researchers have shown that the clustering of magnetic nanoparticles can be detected with magnetic resonance imaging (MRI). They foresee a comprehensive system in which molecular beacons also detect cancerous cells in lab-tested bodily fluids. When appropriate fluids cannot be obtained, other beacons could be introduced into the body. The researchers are also developing magnetic beacons suitable for use in body tissues too deep for optical imaging to work.

"The idea is to use the optical molecular beacons for cellular studies outside the body,” said Gang Bao, associate professor in the department of biomedical engineering jointly operated by Georgia Institute of Technology and Emory University (both in Atlanta, USA). "You can combine that with a delivery system and additional technologies to do shallow tissue imaging.”




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