title: In depth analysis of the quenching of three fluorene-phenylene-based cationic conjugated polyelectrolytes by DNA and DNA bases.
abstract: The interaction of three cationic poly {9,9-bis[N,N-(trimethylammonium)hexyl]fluorene-co-1,4-phenylene} polymers with average chain lengths of ∼6, 12, and 100 repeat units (PFP-NR36(I),12(Br),100(Br)) with both double and single stranded, short and long, DNA and DNA bases have been studied by steady state and time-resolved fluorescence techniques. Fluorescence of PFP-NR3 polymers is quenched with high efficiency by DNA (both double and single stranded) and DNA bases. The resulting quenching plots are sigmoidal and are not accurately described by using a Stern-Volmer quenching mechanism. Here, the quenching mechanism is well modeled in terms of an equilibrium in which a PFP-NR3/DNA aggregate complex is formed which brings polymer chains into close enough proximity to allow interchain excitation energy migration and quenching at aggregate or DNA base traps. Such an analysis gives equilibrium constants of 8.4 × 10(6) (±1.2 × 10(6)) M(-1) for short-dsDNA and 8.6 × 10(6) (±1.7 × 10(6)) M(-1) for short-ssDNA with PFP-NR36(I).
authors.affiliation: School of Chemistry, Bangor University , Bangor, Gwynedd, LL57 2UW, U.K.
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Davies
authors.forename: Peter
authors.initials: P
authors.lastname: Douglas
authors.forename: Hugh D
authors.initials: HD
authors.lastname: Burrows
authors.forename: Bice
authors.initials: B
authors.lastname: Martincigh
authors.forename: Maria da Graça
authors.initials: Mda G
authors.lastname: Miguel
authors.forename: Ullrich
authors.initials: U
authors.lastname: Scherf
authors.forename: Ricardo
authors.initials: R
authors.lastname: Mallavia
authors.forename: Alastair
authors.initials: A
authors.lastname: Douglas
mesh_terms: D000225:Adenine / Q000737:chemistry / Q000378:metabolism; D002412:Cations / Q000737:chemistry; D003596:Cytosine / Q000737:chemistry / Q000378:metabolism; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000737:chemistry* / Q000378:metabolism; D004573:Electrolytes / Q000737:chemistry*; D005449:Fluorenes / Q000737:chemistry; D031541:Fluorescence Resonance Energy Transfer; D006147:Guanine / Q000737:chemistry / Q000378:metabolism; D011108:Polymers / Q000737:chemistry*; D011789:Quantum Theory; D013941:Thymine / Q000737:chemistry / Q000378:metabolism
chemical_list: D002412:Cations; D004277:DNA, Single-Stranded; D004573:Electrolytes; D005449:Fluorenes; D011108:Polymers; C041509:fluorene; D006147:Guanine; D003596:Cytosine; D004247:DNA; D000225:Adenine; D013941:Thymine