A quencher-free molecular beacon design based on pyrene excimer fluorescence using pyrene-labeled UNA (unlocked nucleic acid).

A quencher-free molecular beacon capable of generating pyrene excimer fluorescence has been constructed using strategically positioned pyrene-UNA monomers. Hybridization of a fully complementary RNA target was accompanied by a pyrene excimer emission increase of more than 900%, and detection of RNA in living cells was demonstrated.