title: FRET study of G-quadruplex forming fluorescent oligonucleotide probes at the lipid monolayer interface.
abstract: Spectral properties and G-quadruplex folding ability of fluorescent oligonucleotide probes at the cationic dioctadecyldimethylammonium bromide (DODAB) monolayer interface are reported. Two oligonucleotides, a 19-mer bearing thrombin binding aptamer sequence and a 21-mer with human telomeric sequence, were end-labeled with fluorescent groups (FAM and TAMRA) to give FRET probes F19T and F21T, respectively. The probes exhibited abilities to fold into a quadruplex structure and to bind metal cations (Na(+) and K(+)). Fluorescence spectra of G-quadruplex FRET probes at the monolayer interface are reported for the first time. Investigations included film balance measurements (π-A isotherms) and fluorescence spectra recording using a fiber optic accessory interfaced with a spectrofluorimeter. The effect of the presence of DODAB monolayer, metal cations and the surface pressure of monolayer on spectral behavior of FRET probes were examined. Adsorption of probe at the cationic monolayer interface resulted in the FRET signal enhancement even in the absence of metal cations. Variation in the monolayer surface pressure exerted rather modest effect on the spectral properties of probes. The fluorescence energy transfer efficiency of monolayer adsorbed probes increased significantly in the presence of sodium or potassium ion in subphase, which indicated that the probes retained their cation binding properties when adsorbed at the monolayer interface.
authors.affiliation: Adam Mickiewicz University, Faculty of Chemistry, Umultowska 89b, 61-614 Poznan, Poland.
authors.forename: Angelika
authors.initials: A
authors.lastname: Swiatkowska
authors.affiliation: Adam Mickiewicz University, Faculty of Chemistry, Umultowska 89b, 61-614 Poznan, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Kosman
authors.affiliation: Adam Mickiewicz University, Faculty of Chemistry, Umultowska 89b, 61-614 Poznan, Poland. Electronic address: juskowia@amu.edu.pl.
authors.forename: Bernard
authors.initials: B
authors.lastname: Juskowiak
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D001483:Base Sequence; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D005456:Fluorescent Dyes / Q000737:chemistry*; D054856:G-Quadruplexes; D006801:Humans; D008055:Lipids / Q000737:chemistry; D015345:Oligonucleotide Probes / Q000737:chemistry*; D011188:Potassium / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012964:Sodium / Q000737:chemistry; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*; D016615:Telomere / Q000737:chemistry
chemical_list: D052157:Aptamers, Nucleotide; D005456:Fluorescent Dyes; D008055:Lipids; D015345:Oligonucleotide Probes; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; C081676:thrombin aptamer; C015831:dimethyldioctadecylammonium; D012964:Sodium; D011188:Potassium
keywords: FRET; Fluorescence; Fluorescent oligonucleotide; G-quadruplex; Monolayer