Fluorophores molecular beacon reporter

Tsourkas et al. (2003) reported dual FRET molecular beacon assays, where the donor probe was labeled with either Eu3+ or Tb3+ complex of DTPA-csl24-ethylenediamine (and no quenchers attached). For the Eu3+ complex, the acceptor probe was Cy5-labeled (and no quenchers attached) and for the Tb complex, the acceptor probe was labeled with Cy3 or ROX as a fluorophore and with dabcyl as a quencher. They demonstrated that these pairs of probes detected DNA targets ( 50-mer) with high S/N. 

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