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.
Karlsen, K. K., Okholm, A. H., Kjems, J., & Wengel, J. (2013). A quencher-free molecular beacon design based on pyrene excimer fluorescence using pyrene-labeled UNA (unlocked nucleic acid). Bioorganic & Medicinal Chemistry, 21(20), 6186-6190. https://doi.org/10.1016/j.bmc.2013.04.062