Molecular beacon

Molecular beacons are oligonucleotide probes that can report the presence of specific nucleic acids in homogenous solutions. The terms more often used is molecular beacon probes. Molecular beacons are hairpin shaped molecules with an internally quenched fluorophore whose fluorescence is restored when they bind to a target nucleic acid sequence. This is a novel nonradioactive method for detecting specific sequences of nucleic acids. They are useful in situations where it is either not possible or desirable to isolate the probe-target hybrids from an excess of the hybridization probes.

Molecular Beacon Probes
A typical molecular beacon probe is 25 nucleotides long. The middle 15 nucleotides are complementary to the target DNA and do not base pair with one another, and the five nucleotides at each end are complementary to each other and not to the target DNA.