title: DNA switches on the two-photon efficiency of an ultrabright triphenylamine fluorescent probe specific of AT regions.
abstract: We report on the design and synthesis of two-photon fluorescent triphenylamines bearing two or three vinyl branches terminated by a N-methyl benzimidazolium moiety. The new compounds (TP-2Bzim, TP-3Bzim) are light-up fluorescent DNA probes with a long wavelength emission (>580 nm). Compared to their pyridinium models, the TP-Bzim dyes exhibit a remarkable improvement of both their DNA affinity and fluorescence quantum yield, especially for the two-branch derivative (TP-2Bzim: ΦF = 0.54, Ka = 10(7) M(-1)), resulting in a large fluorescence emission turn-on ratio of up to 140. Concomitantly, the two-photon absorption cross-section of TP-2Bzim is dramatically enhanced upon DNA binding (δ = 1080 vs 110 GM for the free form). This effect of the DNA matrix on the nonlinear absorption is uncovered for the first time. This is attributed to a tight fit of the molecule inside the minor groove of AT-rich DNA which induces geometrical rearrangements in the dye ground state as supported by circular dichroism and molecular modeling data. Consequently, TP-2bzim displays an exceptional two-photon molecular brightness (δ×ΦF = 583 GM), a value unrivalled for a small biofluorophore. These properties enable to image nuclear DNA in fixed cells at submicromolar concentration ([TP-2Bzim] = 100 nM) and to visualize ultrabright foci of centromeric AT-rich chromatin. Finally TP-2Bzim exhibits a high photostability, is live-cell permeant, and does not require RNase treatment. This outstanding combination of optical and biological properties makes TP-2Bzim a bioprobe surpassing the best DNA stainers and paves the way for studying further nonlinear optical processes in DNA.
authors.affiliation: Institut Curie, CNRS UMR-176, Centre Universitaire d'Orsay, Paris-Sud 91405 Orsay Cedex France.
authors.forename: Blaise
authors.initials: B
authors.lastname: Dumat
authors.forename: Guillaume
authors.initials: G
authors.lastname: Bordeau
authors.forename: Elodie
authors.initials: E
authors.lastname: Faurel-Paul
authors.forename: Florence
authors.initials: F
authors.lastname: Mahuteau-Betzer
authors.forename: Nicolas
authors.initials: N
authors.lastname: Saettel
authors.forename: Germain
authors.initials: G
authors.lastname: Metge
authors.forename: Céline
authors.initials: C
authors.lastname: Fiorini-Debuisschert
authors.forename: Fabrice
authors.initials: F
authors.lastname: Charra
authors.forename: Marie-Paule
authors.initials: MP
authors.lastname: Teulade-Fichou
mesh_terms: D016475:3T3 Cells; D000814:Aniline Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D000818:Animals; D002478:Cells, Cultured; D004247:DNA / Q000737:chemistry*; D015342:DNA Probes / Q000138:chemical synthesis / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry*; D019073:HT29 Cells; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D017785:Photons
chemical_list: D000814:Aniline Compounds; D015342:DNA Probes; D005456:Fluorescent Dyes; D004247:DNA