title: On the selective detection of duplex deoxyribonucleic acids by 2,1,3-benzothiadiazole fluorophores.
abstract: A series of 4,7-pi-extended 2,1,3-benzothiadiazoles (BTDs) with different molecular architectures, in particular, the organic dyes based on the 4-(arylethynyl)-7-(4-methoxy)-2,1,3-benzothiazole skeleton, can be used at very low concentrations (down to 10 microM) to detect DNA at 1 ppm in phosphate buffer solutions. Upon binding to DNA, these dyes showed an exponential increase in the fluorescence intensity (hyperchromic effect) and a red shift (1-5 nm) in the long-wavelength emission maxima. Pre-steady state kinetic experiments (stopped-flow) demonstrated the fast dye interaction with the biomacromolecules of DNA with an increase in fluorescence, especially with non-symmetrical BTDs containing an ethynyl spacer. An intercalation model could be proposed based on the photophysical properties, X-ray analysis, and theoretical calculations (ab initio). In this model, the intercalation occurs on the ethynyl side of the BTD, and as a consequence, the PhOMe portion is free to perform the ICT process with the BTD core and stabilizes it in the excited state.
authors.affiliation: Laboratory of Medicinal and Technological Chemistry, University of Brasília (IQ-UnB), Brasilia, DF, CEP 72919-970-P.O.Box 4478-Brasília-DF-Brazil, Brazil. brenno.ipi@gmail.com
authors.forename: Brenno A D
authors.initials: BA
authors.lastname: Neto
authors.forename: Alexandre A M
authors.initials: AA
authors.lastname: Lapis
authors.forename: Fabiana S
authors.initials: FS
authors.lastname: Mancilha
authors.forename: Eraldo L
authors.initials: EL
authors.lastname: Batista
authors.forename: Paulo A
authors.initials: PA
authors.lastname: Netz
authors.forename: Frank
authors.initials: F
authors.lastname: Rominger
authors.forename: Luiz A
authors.initials: LA
authors.lastname: Basso
authors.forename: Diógenes S
authors.initials: DS
authors.lastname: Santos
authors.forename: Jaïrton
authors.initials: J
authors.lastname: Dupont
mesh_terms: D000199:Actins / Q000737:chemistry / Q000235:genetics; D001665:Binding Sites; D004247:DNA / Q000737:chemistry* / Q000235:genetics; D005456:Fluorescent Dyes / Q000737:chemistry*; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D016133:Polymerase Chain Reaction; D015203:Reproducibility of Results; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013830:Thiadiazoles / Q000737:chemistry*
chemical_list: D000199:Actins; D005456:Fluorescent Dyes; D013830:Thiadiazoles; C015700:benzo-1,2,3-thiadiazole; D004247:DNA