Publications

2009

• Détection de peroxyde d'hydrogène résolue en temps à l'aide de nanoparticules Y(1-x)Eu(x)VO(4) luminescentes : application à la signalisation vasculaire
  
  • Nguyên Thanh-Liêm
  , 2009. Les espèces dérivées de l'oxygène comme le peroxyde d'hydrogène jouent un rôle déterminant dans le bon fonctionnement des cellules en tant que molécule de signalisation dans de nombreux processus cellulaires. Les fortes concentrations pouvant être nocive, la régulation de ces substances est vitale. Leur détection résolue en temps est longtemps restée un défi pour la compréhension des mécanismes cellulaires et l'élaboration de traitements efficaces pour des maladies comme l'hypertension ou l'athérosclérose. Ce travail de thèse a ainsi été consacré au développement d'un nouveau type de capteur de substances oxydantes à base de nanoparticules de va- nadate d'Yttrium dopé par de l'Europium. Ces nanoparticules peuvent être internalisées dans les cellules et permettent une détection temporelle de la concentration en peroxyde d'hydrogène dans un domaine étendu de concentrations (1 μM à 5 mM). Après une calibration préalable, ces nanoparticules ont permis de détecter la production de peroxyde d'hydrogène dans les mécanismes de signalisation dans des cellules musculaires lisses vasculaires de souris liés à l'endothéline-1 et au facteur de croissance dérivé des plaquettes. Cette étude comparative a montré deux dynamiques différentes de la production de peroxyde d'hydrogène. Ces dynamiques distinctes peuvent expliquer au moins partiellement la différence de comportement cellulaire.
• Mécanismes de contraste et contrôle du front d’onde en microscopie non linéaire cohérente
  
  • Olivier Nicolas
  , 2009. This Thesis deals with theoretical and experimental aspects of coherent nonlinear microscopy, with a special attention given to contrast mechanisms in Third Harmonic Generation (THG) microscopy.
• Red Blood Cell Sickling in Microfluidic droplets
  
  • Abbyad Paul
  • Baroud Charles N.
  • Tharaux Pierre-Louis
  • Alexandrou Antigoni
  , 2009.
• Spectroscopie et imagerie térahertz des systèmes d'intérêt biologique.
  
  • Podzorov Alexander
  , 2009. Ce travail de thèse présente quelques exemples d'utilisation du rayonnement térahertz pour l'étude de systèmes d'intérêt biologique. Nous avons construit et caractérisé deux dispositifs expérimentaux analogues, chacun conçu de façon à servir à une famille d'applications particulière. Ces dispositifs sont basés sur la génération et la détection des ondes térahertz à l'aides d'antennes photoconductrices pilotées par un laser infrarouge femtoseconde. Un premier dispositif térahertz, dédié à la spectroscopie dans le domaine temporel, permet de caractériser de nombreux systèmes plus ou moins homogènes du point de vue spectroscopique, c'est-à-dire d'obtenir la permittivité complexe du matériau et sa dépendance spectrale. L'étude des nouveaux matériaux transparents en térahertz et des solutions ioniques aqueuses à l'aide de ce spectromètre térahertz a été accomplie. Un deuxième dispositif est consacré au développement de nouvelles techniques d'imagerie térahertz en champ proche avec ouverture. En effet, un contraste fourni par la différence d'absorption des solutions ioniques a permis d'étudier des cellules biologiques de façon non-invasive ; il s'agit ici notamment de l'embryon de drosophile et du nerf sciatique de grenouille. Le lien entre ces deux thématiques est fait par la recherche sur les plasmons-polaritons de surfaces, des ondes électromagnétiques à la surface de métaux, qui, dans certaines conditions, permettent d'exalter la transmission à travers des ouvertures de taille inférieure à la longueur d'onde. Des études spectroscopiques ont permis de comprendre certaines propriétés fondamentales de ces ondes surfaciques en vue de leur application aux nouvelles sondes de champ proche.
• Dynamic aberration correction for multiharmonic microscopy.
  
  • Olivier Nicolas
  • Débarre Delphine
  • Beaurepaire Emmanuel
  Optics Letters, Optical Society of America - OSA Publishing, 2009, 34 (20), pp.3145-7. We demonstrate image-based aberration correction in a third-harmonic generation (THG) microscope. We describe a robust, mostly sample-independent correction scheme relying on prior measurement of the influence of aberration modes produced by a deformable mirror on the quality of THG images. We find that using image sharpness as an image quality metric, correction of N aberration modes is achieved using 2(2N+1) measurements in a variety of samples. We also report aberration correction in combined multiharmonic and two-photon excited fluorescence experiments. Finally, we demonstrate time-dependent adaptive THG imaging in developing embryonic tissue.
• Beam waist measurement for terahertz time domain experiments
  
  • Gallot Guilhem
  • Podzorov Alexander
  • Wojdyla Antoine
  , 2009, pp.1-2. Classical variable aperture masking method is not directly applicable to Time Domain Spectroscopy (TDS) experiments. Here, we present a simple and reliable method for measuring beam waists in TDS. It is based on the successive diffraction by an opaque disk followed by a small circular aperture. © 2009 IEEE. (10.1109/ICIMW.2009.5325575)
  DOI : 10.1109/ICIMW.2009.5325575
• Hole depth dependence of the extraordinary electromagnetic transmission in the terahertz domain
  
  • Podzorov A.
  • Masson J.-B.
  • Gallot Guilhem
  , 2009, pp.1-2. (10.1109/ICIMW.2009.5324713)
  DOI : 10.1109/ICIMW.2009.5324713
• The crystal structure of ORF14 from Sulfolobus islandicus filamentous virus
  
  • Goulet Adeline
  • Spinelli Silvia
  • Blangy Stéphanie
  • van Tilbeurgh Herman
  • Leulliot Nicolas
  • Basta Tamara
  • Prangishvili David
  • Cambillau Christian
  • Campanacci Valérie
  Proteins - Structure, Function and Bioinformatics, Wiley, 2009, 76 (4), pp.1020-1022. (10.1002/prot.22448)
  DOI : 10.1002/prot.22448
• Concepts to build nonlinear optical biomaterials in a bottom-up approach
  
  • Matar G.
  • Duboisset J.
  • Brevet P.-F.
  • Besson F.
  • Benichou E.
  • Deniset-Besseau Ariane
  • Schanne-Klein Marie-Claire
  , 2009, 7487. We have performed Hyper-Rayleigh Scattering (HRS) experiments to measure the quadratic hyperpolarizability of several natural amino acids, in particular tryptophan and tyrosine. Values of (29.6+/-0.4)x10-30 esu for tryptophan and (25.7+/-0.03)x10-30 esu for tyrosine have been found. We have then investigated the dependence of the quadratic hyperpolarizability of tryptophan-rich short peptides as a function of the number of tryptophans in the sequence. The experimental findings indicate that the resulting quadratic hyperpolarizability in these peptides cannot be assumed as the mere coherent superposition of the hyperpolarizabilities of the tryptophans contained in the peptide. Our results unambiguously demonstrate that there must be strong interactions between the tryptophans contained in these short peptides. We have also investigated the case of the collagen triple helix. A second order hyperpolarizability of (1.25+/- 0.05)x10-27 esu for rat-tail type I collagen has been measured. In this case, we have been able to model this effective quadratic hyperpolarizability by summing coherently the nonlinear response of elementary moieties forming the triple helix, as opposed to the previous case of the tryptophan-rich peptides. © 2009 SPIE. (10.1117/12.834084)
  DOI : 10.1117/12.834084
• Multiplexed two-photon microscopy of dynamic biological samples with shaped broadband pulses.
  
  • Pillai Rajesh S.
  • Boudoux Caroline
  • Labroille Guillaume
  • Olivier Nicolas
  • Veilleux Israel
  • Farge Emmanuel
  • Joffre Manuel
  • Beaurepaire Emmanuel
  Optics Express, Optical Society of America - OSA Publishing, 2009, 17 (15), pp.12741-52. Coherent control can be used to selectively enhance or cancel concurrent multiphoton processes, and has been suggested as a means to achieve nonlinear microscopy of multiple signals. Here we report multiplexed two-photon imaging in vivo with fast pixel rates and micrometer resolution. We control broadband laser pulses with a shaping scheme combining diffraction on an optically-addressed spatial light modulator and a scanning mirror allowing to switch between programmable shapes at kiloHertz rates. Using coherent control of the two-photon excited fluorescence, it was possible to perform selective microscopy of GFP and endogenous fluorescence in developing Drosophila embryos. This study establishes that broadband pulse shaping is a viable means for achieving multiplexed nonlinear imaging of biological tissues. (10.1364/OE.17.012741)
  DOI : 10.1364/OE.17.012741
• Structure and function of a novel endonuclease acting on branched DNA substrates.
  
  • Ren Bin
  • Kühn Joelle
  • Meslet-Cladiere Laurence
  • Briffotaux Julien
  • Norais Cedric
  • Lavigne Regis
  • Flament Didier
  • Ladenstein Rudolf
  • Myllykallio Hannu
  EMBO Journal, EMBO Press, 2009, 28 (16), pp.2479-89. We show that Pyrococcus abyssi PAB2263 (dubbed NucS (nuclease for ss DNA) is a novel archaeal endonuclease that interacts with the replication clamp PCNA. Structural determination of P. abyssi NucS revealed a two-domain dumbbell-like structure that in overall does not resemble any known protein structure. Biochemical and structural studies indicate that NucS orthologues use a non-catalytic ssDNA-binding domain to regulate the cleavage activity at another site, thus resulting into the specific cleavage at double-stranded DNA (dsDNA)/ssDNA junctions on branched DNA substrates. Both 3' and 5' extremities of the ssDNA can be cleaved at the nuclease channel that is too narrow to accommodate duplex DNA. Altogether, our data suggest that NucS proteins constitute a new family of structure-specific DNA endonucleases that are widely distributed in archaea and in bacteria, including Mycobacterium tuberculosis. (10.1038/emboj.2009.192)
  DOI : 10.1038/emboj.2009.192
• Coherent nonlinear microscopy system and method with variation of the focal volume in order to probe the nanostructure of organized materials (extension du dépôt français EP20090769543)
  
  • Beaurepaire Emmanuel
  • Olivier Nicolas
  • Débarre Delphine
  • Schanne-Klein Marie-Claire
  • Martin Jean-Louis
  , 2009. A method for the dimensional characterization of a structured material, in which method: an excitation laser beam suitable for coherent nonlinear microscopy is generated, this excitation laser beam being focused in a focal volume within the structured material; signals emitted by the structured material are detected; a plurality of emission patterns, each corresponding to one particular shape of the focal volume, is produced, the particular shapes being obtained for various non-Gaussian spatial profiles of the excitation laser beam wavefront; and on the basis of the emission patterns thus produced, dimensional characteristics of the structured material are deduced therefrom.
• The assignment of Qy(1,0) vibrational structure and Q x for chlorophyll a
  
  • Hughes Joseph L.
  • Conlon B.
  • Krausz E.
  • Wydrzynski T.
  , 2010, 3 (4), pp.1591. We used non-photochemical persistent spectral hole-burning at 1.4 K to investigate the Qy(1,0) vibrational structure of Chl a in a water-soluble chlorophyll-binding protein (WSCP) which exhibits resolved structure in its broadband optical spectra. Franck-Condon vibrational overlap factors were determined from the vibrational hole-burning data and used to simulate the Qy(1,0) spectra. The simulations were not able to accurately reproduce the details of the Qy(1,0) spectrum. This indicates a breakdown of the approximations used for the analysis and demonstrates that vibrationally induced mixing of electronic states (vibronic coupling) is active for Chl a. By considering the inhomogeneous broadening and vibrational hole-burning phenomena in the Qx and Qy(1,0) region of Chl-WSCP in addition to magnetic circular dichroism data, we favor the traditional placement of Qx at ?~570-590 nm rather than the alternate assignment underneath the Qy(1,0) absorption near ?~615-630 nm. © 2010 Elsevier B.V. All rights reserved. (10.1016/j.phpro.2010.01.226)
  DOI : 10.1016/j.phpro.2010.01.226
• Second order hyperpolarizability of the collagen triple helix: Measurement and determination of its physical origin
  
  • Deniset-Besseau Ariane
  • Duboisset J.
  • Loison Claire
  • Benichou E.
  • Hache François
  • Brevet P.-F.
  • Schanne-Klein Marie-Claire
  , 2009, 2009. Collagen is the major protein of the extracellular matrix and plays a central role in the formation of fibrillar and microfibrillar networks, basement membranes, as well as other structures of the connective tissue. As a fundamental brick of the architecture of tissues, it guarantees organs functioning and is crucial in the adaptative response to various tissue injuries. This protein is characterized by triple helical domains and possesses remarkable non linear optical properties. Indeed, collagen fibers exhibit efficient Second Harmonic Generation (SHG) in tissues and SHG microscopy has proved to be a valuable technique to probe the three-dimensional architecture of fibrillar collagen in native and biomimetic tissues and to assess the progression of fibrotic pathologies. However, the nonlinear optical response of fibrillar collagen is not fully characterized yet and quantitative data are required to further process SHG images. We therefore performed Hyper-Rayleigh Scattering (HRS) experiments in order to measure quantitatively the nonlinear optical response of the collagen molecule, and to get insight into the physical origin of high SHG signals observed for fibrillar collagen in tissues. (10.1109/CLEOE-EQEC.2009.5194760)
  DOI : 10.1109/CLEOE-EQEC.2009.5194760
• The thermo- and acido-stable ORF-99 from the archaeal virus AFV1
  
  • Goulet Adeline
  • Spinelli Silvia
  • Blangy Stéphanie
  • van Tilbeurgh Herman
  • Leulliot Nicolas
  • Basta Tamara
  • Prangishvili David
  • Cambillau Christian
  • Campanacci Valérie
  Protein Science, Wiley, 2009, 18 (6), pp.1316-1320. (10.1002/pro.122)
  DOI : 10.1002/pro.122
• Two-photon microscopy with simultaneous standard and extended depth of field using a tunable acoustic gradient-index lens.
  
  • Olivier Nicolas
  • Mermillod-Blondin Alexandre
  • Arnold Craig B.
  • Beaurepaire Emmanuel
  Optics Letters, Optical Society of America - OSA Publishing, 2009, 34 (11), pp.1684-1686. We describe a simple setup that allows depth of field switching at kilohertz rates in a nonlinear microscope. Beam profile and/or divergence are modulated using a tunable, acoustically driven gradient-index fluid lens. We demonstrate two modulation strategies, one based on fast varifocus scanning during each pixel and the other based on pseudo-Bessel beam excitation. Average beam shape is switched every line during scanning, resulting in the interlaced acquisition of two different images. We apply this approach to the simultaneous standard and 4.5x-extended depth-of-field imaging of developing embryos. © 2009 Optical Society of America (10.1364/OL.34.001684)
  DOI : 10.1364/OL.34.001684
• Procédé et dispositif d'acquisition de signaux en microscopie laser à balayage
  
  • Beaurepaire Emmanuel
  • Veilleux Israel
  • Olivier Nicolas
  • Débarre Delphine
  • Martin Jean-Louis
  , 2009.
• HIV-1 IN alternative molecular recognition of DNA induced by raltegravir resistance mutations
  
  • Mouscadet J.-F.
  • Arora Rakesh
  • André J.
  • Lambry Jean-Christophe
  • Delelis O.
  • Malet I.
  • Marcelin A.-G.
  • Calvez V.
  • Tchertanov L.
  Journal of Molecular Recognition, Wiley, 2009, 22 (6), pp.480-494. Virologic failure during treatment with raltegravir, the first effective drug targeting HIV integrase, is associated with two exclusive pathways involving either Q148H/R/K, G140S/A or N155H mutations. We carried out a detailed analysis of the molecular and structural effects of these mutations. We observed no topological change in the integrase core domain, with conservation of a newly identified V-shaped hairpin containing the Q148 residue, in particular. In contrast, the mutations greatly altered the specificity of DNA recognition by integrase. The native residues displayed a clear preference for adenine, whereas the mutant residues strongly favored pyrimidines. Raltegravir may bind to N155 and/or Q148 residues as an adenine bioisoster. This may account for the selected mutations impairing raltegravir binding while allowing alternative DNA recognition by integrase. This study opens up new opportunities for the design of integrase inhibitors active against raltegravir-resistant viruses. Copyright Cop. 2009 John Wiley and Sons, Ltd. Supporting information may be found in the online version of this article. (10.1002/jmr.970)
  DOI : 10.1002/jmr.970
• Unobtrusive interferometer tracking by path length oscillation for multidimensional spectroscopy
  
  • Lee Kevin F.
  • Bonvalet Adeline
  • Nuernberger Patrick
  • Joffre Manuel
  Optics Express, Optical Society of America - OSA Publishing, 2009, 17 (15), pp.12379-12384. We track the path difference between interferometer arms with few-nanometer accuracy without adding optics to the beam path. We measure the interference of a helium-neon beam that copropagates through the interferometer with midinfrared pulses used for multidimensional spectroscopy. This can indicate motion, but not direction. By oscillating the path length of one arm with a mirror on a piezoelectric stack and monitoring the oscillations of the recombined helium-neon beam, the direction can be calculated, and the path delay can be continuously tracked. © 2009 Optical Society of America. (10.1364/OE.17.012379)
  DOI : 10.1364/OE.17.012379
• Apports récents des techniques de quantification de la fibrose pour l'examen anatomopathologique en transplantation rénale
  
  • Servais A.
  • Meas-Yedid V.
  • Morelon E.
  • Strupler Mathias
  • Schanne-Klein Marie-Claire
  • Legendre C.
  • Olivo-Marin J.-C.
  • Thervet É.
  Médecine/Sciences, EDP Sciences, 2009, 25 (11), pp.945-950. La néphropathie chronique d'allogreffe constitue la cause principale de perte des greffons rénaux à long terme. Elle peut être détectée précocement par des biopsies de dépistage effectuées de manière systématique. La classification usuelle, semi-quantitative, souffre d'une mauvaise reproductibilité. Diverses méthodes morphométriques ont donc été développées pour quantifier la fibrose interstitielle qui caractérise cette néphropathie. Certaines utilisent la coloration spécifique par le rouge Sirius. L'analyse d'image couleur par segmentation permet une quantification automatique, rapide et robuste de la fibrose interstitielle. Elle utilise une segmentation couleur associée à une analyse de couleur, de localisation spatiale et de forme sur des biopsies colorées au trichrome de Masson. À l'avenir, l'étude des collagènes fibrillaires par la génération de second harmonique pourrait permettre une approche spécifique des composants de la fibrose. (10.1051/medsci/20092511945)
  DOI : 10.1051/medsci/20092511945
• Measurement of the Second-Order Hyperpolarizability of the Collagen Triple Helix and Determination of Its Physical Origin
  
  • Deniset-Besseau Ariane
  • Duboisset Julien
  • Benichou Emmanuel
  • Hache François
  • Brevet Pierre-Francois
  • Schanne-Klein Marie-Claire
  Journal of Physical Chemistry B, American Chemical Society, 2009, 113 (40), pp.13437-13445. We performed Hyper-Rayleigh Scattering (HRS) experiments to measure the second-order nonlinear optical response of the collagen triple helix and determine the physical origin of second harmonic signals observed in collagenous tissues. HRS experiments yielded a second-order hyperpolarizability of 1.25 x 10(-27) esu for rat-tail type I collagen, a Surprisingly large value considering that collagen presents no strong harmonophore in its amino acid sequence. Polarization-resolved experiments showed intramolecular coherent contributions to the HRS signal along with incoherent contributions that are the only contributions for molecules with dimensions much smaller than the excitation wavelength. We therefore modeled the effective second-order hyperpolarizability of the 290 nm long collagen triple helix by summing coherently the nonlinear response of well-aligned moieties along the triple helix axis. This model was confirmed by HRS measurements after denaturation of the collagen triple helix and for a collagen-like short model peptide [(Pro-Pro-Gly)(10)](3). We concluded that the large collagen nonlinear response originates in the tight alignment of a large number of small and weakly efficient harmonophores, presumably the peptide bonds, resulting in a coherent amplification of the nonlinear signal. (10.1021/jp9046837)
  DOI : 10.1021/jp9046837
• Single europium-doped nanoparticles measure temporal pattern of reactive oxygen species production inside cells
  
  • Casanova Didier
  • Bouzigues Cédric
  • Nguyên Thanh-Liêm
  • Ramodiharilafy Rivo O.
  • Bouzhir-Sima Latifa
  • Gacoin Thierry
  • Boilot Jean-Pierre
  • Tharaux Pierre-Louis
  • Alexandrou Antigoni
  Nature Nanotechnology, Nature Publishing Group, 2009, 4 (9), pp.581. Low concentrations of reactive oxygen species, notably hydrogen peroxide (H 2 O 2), mediate various signalling processes in the cell. Production of these signals is highly regulated and a suitable probe is needed to measure these events. Here, we show that a probe based on a single nanoparticle can quantitatively measure transient H 2 O 2 generation in living cells. The Y 0.6 Eu 0.4 VO 4 nanoparticles undergo photoreduction under laser irradiation but re-oxidize in the presence of oxidants, leading to a recovery in luminescence. Our probe can be regenerated and reliably detects intracellular H 2 O 2 with a 30-s temporal resolution and a dynamic range of 1-45?M. The differences in the timing of intracellular H 2 O 2 production triggered by different signals were also measured using these nanoparticles. Although the probe is not selective towards H 2 O 2, in many signalling processes H 2 O 2 is, however, the dominant oxidant. In conjunction with appropriate controls, this probe is a powerful tool for unravelling pathways that involve reactive oxygen species. Cop. 2009 Macmillan Publishers Limited. All rights reserved. (10.1038/nnano.2009.200)
  DOI : 10.1038/nnano.2009.200
• Inferring maps of forces inside cell membrane microdomains
  
  • Masson J.-B.
  • Casanova Didier
  • Türkcan Silvan
  • Voisinne G.
  • Popoff Michel
  • Vergassola M.
  • Alexandrou Antigoni
  Physical Review Letters, American Physical Society, 2009, 102 (4), pp.48103. Mapping of the forces on biomolecules in cell membranes has spurred the development of effective labels, e.g., organic fluorophores and nanoparticles, to track trajectories of single biomolecules. Standard methods use particular statistics, namely the mean square displacement, to analyze the underlying dynamics. Here, we introduce general inference methods to fully exploit information in the experimental trajectories, providing sharp estimates of the forces and the diffusion coefficients in membrane microdomains. Rapid and reliable convergence of the inference scheme is demonstrated on trajectories generated numerically. The method is then applied to infer forces and potentials acting on the receptor of the toxin labeled by lanthanide-ion nanoparticles. Our scheme is applicable to any labeled biomolecule and results show its general relevance for membrane compartmentation. Cop. 2009 The American Physical Society. (10.1103/PhysRevLett.102.048103)
  DOI : 10.1103/PhysRevLett.102.048103
• Femtosecond spectroscopy from the perspective of a global multidimensional response function
  
  • Nuernberger Patrick
  • Lee Kevin F.
  • Joffre Manuel
  Accounts of Chemical Research, American Chemical Society, 2009, 42 (9), pp.1433-1441. At the microscopic level, multidimensional response functions, such as the nonlinear optical susceptibility or the time-ordered response function, are commonly used tools in nonlinear optical spectroscopy for determining the nonlinear polarization resulting from an arbitrary excitation. In this Account, we point out that the approach successfully developed for the nonlinear polarization can also be used in the case of a directly observable macroscopic quantity. This observable can be, for example, the electric field radiated in a nonlinear mixing experiment, the rate of fluorescence resulting from one- or two-photon absorption, or the rate of a photochemical reaction. For each of these physical processes, perturbation theory can be used to expand the measured quantity in a power series of the exciting field, and an appropriate global response function can be introduced for each order of perturbation. At order n, the multidimensional response function will depend on n variables (either time or frequency) and have the same general properties as the nonlinear susceptibility resulting, for example, from time invariance or causality. The global response function is introduced in this Account in close analogy with the nonlinear susceptibility or the time-ordered microscopic response. We discuss various applications of the global response function formalism. For example, it can be shown that in the weak field limit, a stationary signal induced in a time-invariant system is independent of the spectral phase of the exciting field. Although this result had been demonstrated previously, the global response function enables its derivation in a more general way because no specific microscopic model is needed. Multidimensional spectroscopy is obviously ideally suited to measure the global multidimensional response function. It is shown that the second (or third)-order response can be exactly measured with 2D (or 3D) spectroscopy by taking into account the exact shape of the exciting pulses. In the case of a 2D measurement of the third-order response, a particular projection of the complete 3D response function is actually measured. This projection can be related to a mixed time and frequency representation of the response function when the pulses are assumed to be infinitely short. We thus show that the global response function is a useful tool for deriving general results and that it should help in designing future experimental schemes for femtosecond spectroscopy. Cop. 2009 American Chemical Society. (10.1021/ar900001w)
  DOI : 10.1021/ar900001w
• Application of time-resolved circular dichroism to the study of conformational changes in photochemical and photobiological processes
  
  • Hache François
  Journal of Photochemistry and Photobiology A: Chemistry, Elsevier, 2009, 204 (2-3), pp.137-143. Circular dichroism is known to be a very sensitive probe of the molecular conformation and implementation of this technique in a pump-probe experiment is very appealing to access information on the dynamics of conformational changes occurring in photochemical or photobiological processes. In the past years, we have developed such techniques in various ways and applied them to several chemical or biological studies which are presented in this article. Applications concern spectroscopic studies of the excited state in ruthenium tris(bipyridyl) or tris(phenanthroline), dynamics of conformational changes in photoexcited binaphthol and study of the conformational changes occurring in photolyzed carboxy-myoglobin. Extension of these techniques towards biological issues such as protein folding is discussed. Cop. 2009 Elsevier B.V. All rights reserved. (10.1016/j.jphotochem.2009.03.012)
  DOI : 10.1016/j.jphotochem.2009.03.012