title: Fluorescein provides a resonance gate for FRET from conjugated polymers to DNA intercalated dyes.
abstract: Fluorescence spectra show that excitation of the cationic water-soluble conjugated polymer poly[(1,4-phenylene)-2,7-[9,9-bis(6'-N,N,N-trimethylammonium)-hexyl]fluorene diiodide] (1) results in inefficient fluorescence resonance energy transfer (FRET) to ethidium bromide (EB) intercalated within double-stranded DNA (dsDNA). When fluorescein (Fl) is attached to one terminus of the dsDNA, there is efficient FRET from 1 through Fl to EB. The cascading energy-transfer process was examined mechanistically via fluorescence decay kinetics and fluorescence anisotropy measurements. These experiments show that the proximity and conformational freedom of Fl provide a FRET gate to dyes intercalated within DNA which are optically amplified by the properties of the conjugated polymer. The overall process provides a substantial improvement over previous homogeneous conjugated polymer based DNA sensors, namely, in the form of improved selectivity.
authors.affiliation: Department of Chemistry, Institute for Polymers and Organic Solids, University of California, Santa Barbara, California 93106, USA.
authors.forename: Shu
authors.initials: S
authors.lastname: Wang
authors.forename: Brent S
authors.initials: BS
authors.lastname: Gaylord
authors.forename: Guillermo C
authors.initials: GC
authors.lastname: Bazan
mesh_terms: D001483:Base Sequence; D004396:Coloring Agents / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D004996:Ethidium / Q000737:chemistry; D019793:Fluorescein / Q000737:chemistry*; D005454:Fluorescence Polarization; D031541:Fluorescence Resonance Energy Transfer; D007364:Intercalating Agents / Q000737:chemistry*; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: D004396:Coloring Agents; D007364:Intercalating Agents; D011108:Polymers; D004247:DNA; D004996:Ethidium; D019793:Fluorescein