Figure 2.

Gene expression analysis using dual-fluorescence resonance energy transfer (dual-FRET) molecular beacons. In solution, molecular beacons assume a stem-loop structure that juxtaposes the fluorescent dye and quencher, inhibiting fluorescence (top). With transcription of a gene of interest, molecular beacons preferentially undergo sequence-specific base pairing with the gene transcript (bottom). This removes the fluorescent dyes from quencher proximity and allows laser excitation of the donor dye, FRET that excites the acceptor dye, and detection/collection of cells on the basis of acceptor dye emission.