Peer-reviewed Publications |
Blandin, P., Druon, F., Hanna, M., Leveque-Fort, S., Lesvigne, C., Couderc, V., Leproux, P., Tonello, A., & Georges, P. (2008). Picosecond polarized supercontinuum generation controlled by intermodal four-wave mixing for fluorescence lifetime imaging microscopy. OPTICS EXPRESS, 16(23), 18844–18849.
Résumé: We present the generation of a picosecond polarized supercontinuum in highly birefringent multimodal microstructured fiber. The initial steps of the spectral broadening are dominated by intermodal four-wave mixing controlled by the specific fiber design. Using a low repetition rate ultra-stable solid state laser, a pulse train well-suited for versatile time-domain fluorescence lifetime imaging applications is obtained. (C) 2008 Optical Society of America
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Bojarska, E., Kazimierczuk, Z., Mouchard, C., Tfibel, F., & Fontaine-Aupart, M. - P. (2008). UVC induced oxidation of chloropurines: excited singlet and triplet pathways for the photoreaction. PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES, 7(9), 1054–1062.
Résumé: The phototransformation of 2-chloro. 6-chloro and 2,6-dichloropurines under UVC excitation (254 nm) has been studied and the major photoproducts have been identified using absorption spectroscopy, HPLC and mass spectrometry It was shown that hydropurines were formed as the main products for all three investigated compounds both in the presence and absence of oxygen. In the case of 6-chloro- and 2,6-dichloropurine, a photodimer is also formed as a minor photoproduct in the absence of oxygen but is efficiently quenched in the presence of oxygen. Nanosecond photolysis experiments also revealed significant intersystem crossing to the triplet state of the chloropurines which has been characterized (transient absorption spectra, triplet formation quantum yields and rate constants of quenching by oxygen, Mn2+ ions and ground state). Experimental evidence allows to Conclude that the triplet state is involved in photodimer formation whereas the hydroxypurine is formed from the reaction of the excited singlet state of chloropurines with the solvent (water addition) through heterolytic C-Cl bond rupture. Mass spectrometry and H-1 NMR results allowed to propose a chemical pathway for dimer formation in the case of 2,6-dichloropurine in a two-step process: first a homolytic rupture of C-Cl bond in the triplet state of the molecule with the formation of purinyl radicals, which subsequently react with an excess of ground state molecules and/or hydroxypurine primarily formed.
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Briandet, R., Lacroix-Gueu, P., Renault, M., Lecart, S., Meylheuc, T., Bidnenko, E., Steenkeste, K., Bellon-Fontaine, M. - N., & Fontaine-Aupart, M. - P. (2008). Fluorescence correlation spectroscopy to study diffusion and reaction of bacteriophages inside biofilms. APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 74(7), 2135–2143.
Résumé: In the natural environment, most of the phages that target bacteria are thought to exist in biofilm ecosystems. The purpose of this study was to gain a clearer understanding of the reactivity of these viral particles when they come into contact with bacteria embedded in biofilms. Experimentally, we quantified lactococcal c2 phage diffusion and reaction through model biofilms using in situ fluorescence correlation spectroscopy with two-photon excitation. Correlation curves for fluorescently labeled c2 phage in nonreacting Stenotrophomonas maltophilia biofilms indicated that extracellular polymeric substances did not provide significant resistance to phage penetration and diffusion, even though penetration and diffusion were sometimes restricted because of the noncontractile tail of the viral particle. Fluctuations in the fluorescence intensity of the labeled phage were detected throughout the thickness of biofilms formed by c2-sensitive and c2-resistant strains of Lactococcus lactis but could never be correlated with time, revealing that the phage was immobile. This finding confirmed that recognition binding receptors for the viral particles were present on the resistant bacterial cell wall. Taken together, our results suggest that biofilms may act as “active” phage reservoirs that can entrap and amplify viral particles and protect them from harsh environments.
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Actes de Conférences |
Blandin, P., Leveque-Fort, S., Lecart, S., Druon, F., Georges, P., Cossec, J. C., Potier, M. C., & Lenkei, Z. (2008). FRET detection in the plasma membrane using Total Internal Reflection Fluorescence Lifetime Imaging Microscopy. In 2008 CONFERENCE ON LASERS AND ELECTRO-OPTICS & QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (pp. 252–253).
Résumé: We developed a Total Internal Reflection Fluorescence Lifetime Imaging Microscope to perform functional imaging of living cells membranes labeled with FRET couples. Forster Resonance Energy Transfer efficiency can thus be followed with subwavelength axial resolution. (C) 2008 Optical Society of America
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Guilbaud, O., Ros, D., Kazamias, S., Zielbauer, B., Habib, J., Pittman, M., Cassou, K., Ple, F., Farinet, M., Klisnick, A., de Dortan, F., Lacombe, S., Porcel, E., Le Sech, C., du Penhoat, M. - A., Touati, A., Marsi, M., Fajardo, M., Zeitoun, P., & Joyeux, D. (2008). LASERIX: first record from the plant. In UVX 2008: 9E COLLOQUE SUR LES SOURCES COHERENTES ET INCOHERENTES UV (pp. 57–63).
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