title: Fluorescent dyes undergoing intramolecular proton transfer with improved sensitivity to surface charge in lipid bilayers.
abstract: 4'-(Dialkylamino)-3-hydroxyflavones are characterized by an excited-state proton transfer reaction between two tautomeric excited states, which results in two emission bands well separated on the wavelength scale. Due to the high sensitivity of the relative intensities of the two emission bands to solvent polarity, hydrogen bonding and local electric fields, these dyes found numerous applications in biomembrane studies. In order to further improve their fluorescence characteristics, we have synthesized new dyes where the 2-phenyl group is substituted with a 2-thienyl group. In organic solvents, the new dyes exhibit red shifted absorption and dual fluorescence. Although they show lower sensitivity to solvent polarity and H-bond donor ability (acidicity) than their parent 3-hydroxyflavone dyes, they exhibit a much higher sensitivity to solvent H-bond acceptor ability (basicity). Moreover, when tested in lipid vesicles of different surface charge, the new dyes show much better resolved dual emission and higher sensitivity to the surface charge of lipid bilayers than the parent dyes. The response of the new dyes to surface charge is probably connected with the H-bond basicity of the membrane surface, which is the highest for negatively charged surfaces. As a consequence, the new dyes appear as prospective fluorophores for the development of new fluorescent probes for biomembranes.
authors.affiliation: Département de Pharmacologie et Physicochimie, Photophysique des Interactions Biomoléculaires, UMR 7175, Institut Gilbert Laustriat, 74 Route du Rhin, Université Louis Pasteur (Strasbourg I), BP 60024, 67401, Illkirch, France.
authors.forename: Gora
authors.initials: G
authors.lastname: M'Baye
authors.forename: Andrey S
authors.initials: AS
authors.lastname: Klymchenko
authors.forename: Dmytro A
authors.initials: DA
authors.lastname: Yushchenko
authors.forename: Volodymyr V
authors.initials: VV
authors.lastname: Shvadchak
authors.forename: Turan
authors.initials: T
authors.lastname: Ozturk
authors.forename: Yves
authors.initials: Y
authors.lastname: Mély
authors.forename: Guy
authors.initials: G
authors.lastname: Duportail
mesh_terms: D002867:Chromones / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D015394:Molecular Structure; D011522:Protons; D012680:Sensitivity and Specificity; D013499:Surface Properties
chemical_list: C479534:3-hydroxychromone; D002867:Chromones; D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D011522:Protons