You will find below the publication list of our pole.
For the publication list of each pole member, please see his/her personal webpage.
2017 |
Photoinduced Chromophore Hydration in the Fluorescent Protein Dreiklang Is Triggered by Ultrafast Excited-State Proton Transfer Coupled to a Low-Frequency Vibration Article de journal F Lacombat; P Plaza; M -A Plamont; A Espagne Journal of Physical Chemistry Letters, 8 (7), p. 1489–1495, 2017. @article{Lacombat:2017, title = {Photoinduced Chromophore Hydration in the Fluorescent Protein Dreiklang Is Triggered by Ultrafast Excited-State Proton Transfer Coupled to a Low-Frequency Vibration}, author = {F Lacombat and P Plaza and M -A Plamont and A Espagne}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017130354&doi=10.1021%2facs.jpclett.7b00348&partnerID=40&md5=dba41290a37553caaabb354a87ad0ec6}, doi = {10.1021/acs.jpclett.7b00348}, year = {2017}, date = {2017-01-01}, journal = {Journal of Physical Chemistry Letters}, volume = {8}, number = {7}, pages = {1489--1495}, abstract = {Because of growing applications in advanced fluorescence imaging, the mechanisms and dynamics of photoinduced reactions in reversibly photoswitchable fluorescent proteins are currently attracting much interest. We report the first time-resolved study of the photoswitching of Dreiklang, so far the only fluorescent protein to undergo reversible photoinduced chromophore hydration. Using broadband femtosecond transient absorption spectroscopy, we show that the reaction is triggered by an ultrafast deprotonation of the chromophore phenol group in the excited state in 100 fs. This primary step is accompanied by coherent oscillations that we assign to its coupling with a low-frequency mode, possibly a deformation of the chromophore hydrogen bond network. A ground-state intermediate is formed in the picosecond-nanosecond regime that we tentatively assign to the deprotonated water adduct. We suggest that proton ejection from the phenol group leads to a charge transfer from the phenol to the imidazolinone ring, which triggers imidazolinone protonation by nearby Glu222 and catalyzes the addition of the water molecule. © 2017 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Because of growing applications in advanced fluorescence imaging, the mechanisms and dynamics of photoinduced reactions in reversibly photoswitchable fluorescent proteins are currently attracting much interest. We report the first time-resolved study of the photoswitching of Dreiklang, so far the only fluorescent protein to undergo reversible photoinduced chromophore hydration. Using broadband femtosecond transient absorption spectroscopy, we show that the reaction is triggered by an ultrafast deprotonation of the chromophore phenol group in the excited state in 100 fs. This primary step is accompanied by coherent oscillations that we assign to its coupling with a low-frequency mode, possibly a deformation of the chromophore hydrogen bond network. A ground-state intermediate is formed in the picosecond-nanosecond regime that we tentatively assign to the deprotonated water adduct. We suggest that proton ejection from the phenol group leads to a charge transfer from the phenol to the imidazolinone ring, which triggers imidazolinone protonation by nearby Glu222 and catalyzes the addition of the water molecule. © 2017 American Chemical Society. |
Programmed Self-Assembly of a Biochemical and Magnetic Scaffold to Trigger and Manipulate Microtubule Structures Article de journal R Ducasse; W A Wang; M G J Navarro; N Debons; A Colin; J Gautier; J M Guigner; F Guyot; Z Gueroui Scientific Reports, 7 , p. 11, 2017, ISSN: 2045-2322. @article{RN19c, title = {Programmed Self-Assembly of a Biochemical and Magnetic Scaffold to Trigger and Manipulate Microtubule Structures}, author = {R Ducasse and W A Wang and M G J Navarro and N Debons and A Colin and J Gautier and J M Guigner and F Guyot and Z Gueroui}, url = {<Go to ISI>://WOS:000410297900058}, doi = {10.1038/s41598-017-10297-y}, issn = {2045-2322}, year = {2017}, date = {2017-01-01}, journal = {Scientific Reports}, volume = {7}, pages = {11}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Redesigning the QA binding site of Photosystem II allows reduction of exogenous quinones Article de journal H -Y Fu; D Picot; Y Choquet; G Longatte; A Sayegh; J Delacotte; M Guille-Collignon; F Lemaýtre; F Rappaport; F -A Wollman Nature Communications, 8 , 2017. @article{Fu:2017, title = {Redesigning the QA binding site of Photosystem II allows reduction of exogenous quinones}, author = {H -Y Fu and D Picot and Y Choquet and G Longatte and A Sayegh and J Delacotte and M Guille-Collignon and F Lema\'{y}tre and F Rappaport and F -A Wollman}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030692080&doi=10.1038%2fncomms15274&partnerID=40&md5=d602745399324d5a5eb6c25bd2e5a7c7}, doi = {10.1038/ncomms15274}, year = {2017}, date = {2017-01-01}, journal = {Nature Communications}, volume = {8}, abstract = {Strategies to harness photosynthesis from living organisms to generate electrical power have long been considered, yet efficiency remains low. Here, we aimed to reroute photosynthetic electron flow in photosynthetic organisms without compromising their phototrophic properties. We show that 2,6-dimethyl-p-benzoquinone (DMBQ) can be used as an electron mediator to assess the efficiency of mutations designed to engineer a novel electron donation pathway downstream of the primary electron acceptor QA of Photosystem (PS) II in the green alga Chlamydomonas reinhardtii. Through the use of structural prediction studies and a screen of site-directed PSII mutants we show that modifying the environment of the QA site increases the reduction rate of DMBQ. Truncating the C-terminus of the PsbT subunit protruding in the stroma provides evidence that shortening the distance between QA and DMBQ leads to sustained electron transfer to DMBQ, as confirmed by chronoamperometry, consistent with a bypass of the natural QA7circ; to QB pathway.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Strategies to harness photosynthesis from living organisms to generate electrical power have long been considered, yet efficiency remains low. Here, we aimed to reroute photosynthetic electron flow in photosynthetic organisms without compromising their phototrophic properties. We show that 2,6-dimethyl-p-benzoquinone (DMBQ) can be used as an electron mediator to assess the efficiency of mutations designed to engineer a novel electron donation pathway downstream of the primary electron acceptor QA of Photosystem (PS) II in the green alga Chlamydomonas reinhardtii. Through the use of structural prediction studies and a screen of site-directed PSII mutants we show that modifying the environment of the QA site increases the reduction rate of DMBQ. Truncating the C-terminus of the PsbT subunit protruding in the stroma provides evidence that shortening the distance between QA and DMBQ leads to sustained electron transfer to DMBQ, as confirmed by chronoamperometry, consistent with a bypass of the natural QA7circ; to QB pathway. |
Refolding of Aggregation-Prone ScFv Antibody Fragments Assisted by Hydrophobically Modified Poly(sodium acrylate) Derivatives Article de journal N Martin; N Costa; F Wien; F M Winnik; C Ortega; A Herbet; D Boquet; C Tribet Macromolecular Bioscience, 17 (2), 2017. @article{Martin:2017, title = {Refolding of Aggregation-Prone ScFv Antibody Fragments Assisted by Hydrophobically Modified Poly(sodium acrylate) Derivatives}, author = {N Martin and N Costa and F Wien and F M Winnik and C Ortega and A Herbet and D Boquet and C Tribet}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983541279&doi=10.1002%2fmabi.201600213&partnerID=40&md5=2dfcbb05e216980d1285b2ac92c56bde}, doi = {10.1002/mabi.201600213}, year = {2017}, date = {2017-01-01}, journal = {Macromolecular Bioscience}, volume = {17}, number = {2}, abstract = {ScFv antibody fragments are a promising alternative to full-length antibodies for both therapeutic and diagnosis applications. They can be overexpressed in bacteria, which enables easy large scale production. Since scFv are artificial constructs, they are poorly soluble and prone to aggregation, which makes them difficult to manipulate and to refold. Here, stabilization and refolding of scFv fragments from urea-unfolded solutions are reported based on the use of micromolar amounts of polymers playing the role of artificial chaperons. Using fluorescence correlation spectroscopy, the size and aggregation number of complexes of scFv with unmodified or hydrophobically modified poly(sodium acrylate) are determined. The evolution of the secondary structure along the refolding procedure, in the presence or absence of 0.4 m l-arginine at scFv:polymer textless 1:5 (w/w), is determined by high-sensitivity synchrotron-radiation circular dichroism. Measurements reveal that refolding in the presence of polymers yields native-like secondary structure, though a different folding pathway can be followed compared to refolding in the absence of polymer. This is the first report on the use of macromolecular additives to assist refolding of a multidomain protein of therapeutic interest. (Figure presented.). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim}, keywords = {}, pubstate = {published}, tppubtype = {article} } ScFv antibody fragments are a promising alternative to full-length antibodies for both therapeutic and diagnosis applications. They can be overexpressed in bacteria, which enables easy large scale production. Since scFv are artificial constructs, they are poorly soluble and prone to aggregation, which makes them difficult to manipulate and to refold. Here, stabilization and refolding of scFv fragments from urea-unfolded solutions are reported based on the use of micromolar amounts of polymers playing the role of artificial chaperons. Using fluorescence correlation spectroscopy, the size and aggregation number of complexes of scFv with unmodified or hydrophobically modified poly(sodium acrylate) are determined. The evolution of the secondary structure along the refolding procedure, in the presence or absence of 0.4 m l-arginine at scFv:polymer textless 1:5 (w/w), is determined by high-sensitivity synchrotron-radiation circular dichroism. Measurements reveal that refolding in the presence of polymers yields native-like secondary structure, though a different folding pathway can be followed compared to refolding in the absence of polymer. This is the first report on the use of macromolecular additives to assist refolding of a multidomain protein of therapeutic interest. (Figure presented.). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim |
Repair of (6-4) Lesions in DNA by (6-4) Photolyase: 20 Years of Quest for the Photoreaction Mechanism Article de journal J Yamamoto; P Plaza; K Brettel Photochemistry and Photobiology, 93 (1), p. 51–66, 2017. @article{Yamamoto:2017a, title = {Repair of (6-4) Lesions in DNA by (6-4) Photolyase: 20 Years of Quest for the Photoreaction Mechanism}, author = {J Yamamoto and P Plaza and K Brettel}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011581630&doi=10.1111%2fphp.12696&partnerID=40&md5=4127461fd365fb839dfef3ed244ba606}, doi = {10.1111/php.12696}, year = {2017}, date = {2017-01-01}, journal = {Photochemistry and Photobiology}, volume = {93}, number = {1}, pages = {51--66}, abstract = {Exposure of DNA to ultraviolet (UV) light from the Sun or from other sources causes the formation of harmful and carcinogenic crosslinks between adjacent pyrimidine nucleobases, namely cyclobutane pyrimidine dimers and pyrimidine(6\textendash4)pyrimidone photoproducts. Nature has developed unique flavoenzymes, called DNA photolyases, that utilize blue light, that is photons of lower energy than those of the damaging light, to repair these lesions. In this review, we focus on the chemically challenging repair of the (6\textendash4) photoproducts by (6\textendash4) photolyase and describe the major events along the quest for the reaction mechanisms, over the 20 years since the discovery of (6-4) photolyase. © 2016 The American Society of Photobiology}, keywords = {}, pubstate = {published}, tppubtype = {article} } Exposure of DNA to ultraviolet (UV) light from the Sun or from other sources causes the formation of harmful and carcinogenic crosslinks between adjacent pyrimidine nucleobases, namely cyclobutane pyrimidine dimers and pyrimidine(6–4)pyrimidone photoproducts. Nature has developed unique flavoenzymes, called DNA photolyases, that utilize blue light, that is photons of lower energy than those of the damaging light, to repair these lesions. In this review, we focus on the chemically challenging repair of the (6–4) photoproducts by (6–4) photolyase and describe the major events along the quest for the reaction mechanisms, over the 20 years since the discovery of (6-4) photolyase. © 2016 The American Society of Photobiology |
Resonant out-of-phase fluorescence microscopy and remote imaging overcome spectral limitations Article de journal J Quérard; R Zhang; Z Kelemen; M -A Plamont; X Xie; R Chouket; I Roemgens; Y Korepina; S Albright; E Ipendey; M Volovitch; H L Sladitschek; P Neveu; L Gissot; A Gautier; J -D Faure; V Croquette; T Le Saux; L Jullien Nature Communications, 8 (1), 2017. @article{Querard:2017a, title = {Resonant out-of-phase fluorescence microscopy and remote imaging overcome spectral limitations}, author = {J Qu\'{e}rard and R Zhang and Z Kelemen and M -A Plamont and X Xie and R Chouket and I Roemgens and Y Korepina and S Albright and E Ipendey and M Volovitch and H L Sladitschek and P Neveu and L Gissot and A Gautier and J -D Faure and V Croquette and T Le Saux and L Jullien}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031811446&doi=10.1038%2fs41467-017-00847-3&partnerID=40&md5=c320b3585a15085c192d20ee6faa36fa}, doi = {10.1038/s41467-017-00847-3}, year = {2017}, date = {2017-01-01}, journal = {Nature Communications}, volume = {8}, number = {1}, abstract = {We present speed out-of-phase imaging after optical modulation (OPIOM), which exploits reversible photoswitchable fluorophores as fluorescent labels and combines optimized periodic illumination with phase-sensitive detection to specifically retrieve the label signal. Speed OPIOM can extract the fluorescence emission from a targeted label in the presence of spectrally interfering fluorophores and autofluorescence. Up to four fluorescent proteins exhibiting a similar green fluorescence have been distinguished in cells either sequentially or in parallel. Speed OPIOM is compatible with imaging biological processes in real time in live cells. Finally speed OPIOM is not limited to microscopy but is relevant for remote imaging as well, in particular, under ambient light. Thus, speed OPIOM has proved to enable fast and quantitative live microscopic and remote-multiplexed fluorescence imaging of biological samples while filtering out noise, interfering fluorophores, as well as ambient light. © 2017 The Author(s).}, keywords = {}, pubstate = {published}, tppubtype = {article} } We present speed out-of-phase imaging after optical modulation (OPIOM), which exploits reversible photoswitchable fluorophores as fluorescent labels and combines optimized periodic illumination with phase-sensitive detection to specifically retrieve the label signal. Speed OPIOM can extract the fluorescence emission from a targeted label in the presence of spectrally interfering fluorophores and autofluorescence. Up to four fluorescent proteins exhibiting a similar green fluorescence have been distinguished in cells either sequentially or in parallel. Speed OPIOM is compatible with imaging biological processes in real time in live cells. Finally speed OPIOM is not limited to microscopy but is relevant for remote imaging as well, in particular, under ambient light. Thus, speed OPIOM has proved to enable fast and quantitative live microscopic and remote-multiplexed fluorescence imaging of biological samples while filtering out noise, interfering fluorophores, as well as ambient light. © 2017 The Author(s). |
Reversible and Dynamical Control of Aggregation and Soft Adhesion of Ŧ-Responsive Polymer-Coated Colloids Article de journal Giuseppe Boniello; Jeremy Malinge; Christophe Tribet; Emmanuelle Marie; Drazen Zanchi Colloids and Surfaces a-Physicochemical and Engineering Aspects, 532 , p. 510-515, 2017, ISSN: 0927-7757. @article{RN3h, title = {Reversible and Dynamical Control of Aggregation and Soft Adhesion of {T}-Responsive Polymer-Coated Colloids}, author = {Giuseppe Boniello and Jeremy Malinge and Christophe Tribet and Emmanuelle Marie and Drazen Zanchi}, doi = {10.1016/j.colsurfa.2017.04.011}, issn = {0927-7757}, year = {2017}, date = {2017-01-01}, journal = {Colloids and Surfaces a-Physicochemical and Engineering Aspects}, volume = {532}, pages = {510-515}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Selective Electrochemical Bleaching of the Outer Leaflet of Fluorescently Labelled Giant Liposomes Article de journal Olivier Buriez; Ana Isabel Perez Jimenez; Lylian Challier; Eric Aït-Yahiatène; Jerome Delacotte; Eric Labbe Chemistry A European Journal, 23 , p. 6781-6787, 2017. @article{RID:0519170943437-64, title = {Selective Electrochemical Bleaching of the Outer Leaflet of Fluorescently Labelled Giant Liposomes}, author = {Olivier Buriez and Ana Isabel Perez Jimenez and Lylian Challier and Eric A\"{i}t-Yahiat\`{e}ne and Jerome Delacotte and Eric Labbe}, year = {2017}, date = {2017-01-01}, journal = {Chemistry A European Journal}, volume = {23}, pages = {6781-6787}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Syntheses and kinetic studies of cyclisation-based self-immolative spacers Article de journal S Huvelle; A Alouane; T Le Saux; L Jullien; F Schmidt Organic and Biomolecular Chemistry, 15 (16), p. 3435–3443, 2017. @article{Huvelle:2017, title = {Syntheses and kinetic studies of cyclisation-based self-immolative spacers}, author = {S Huvelle and A Alouane and T Le Saux and L Jullien and F Schmidt}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017654758&doi=10.1039%2fc7ob00121e&partnerID=40&md5=b3efbccb7d9af044089b4be18ab3b100}, doi = {10.1039/c7ob00121e}, year = {2017}, date = {2017-01-01}, journal = {Organic and Biomolecular Chemistry}, volume = {15}, number = {16}, pages = {3435--3443}, abstract = {Kinetic analysis of the disassembly of self-immolative spacers based on cyclisation processes was performed. Five compounds were synthesized belonging to two different series, and their kinetic constants were determined. Electron-donating substituents gave a slight acceleration but the main effect was steric, and the Thorpe-Ingold effect was indeed particularly effective. Comparison with the self-immolative spacers based on elimination processes showed that cyclisations gave comparable or lower rate, but the corresponding spacers are more difficult to modulate. © The Royal Society of Chemistry.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Kinetic analysis of the disassembly of self-immolative spacers based on cyclisation processes was performed. Five compounds were synthesized belonging to two different series, and their kinetic constants were determined. Electron-donating substituents gave a slight acceleration but the main effect was steric, and the Thorpe-Ingold effect was indeed particularly effective. Comparison with the self-immolative spacers based on elimination processes showed that cyclisations gave comparable or lower rate, but the corresponding spacers are more difficult to modulate. © The Royal Society of Chemistry. |
Ultrafast flavin photoreduction in an oxidized animal (6-4) photolyase through an unconventional tryptophan tetrad Article de journal P R Martin; F Lacombat; A Espagne; N Dozova; P Plaza; J Yamamoto; P Müller; K Brettel; A De La Lande Physical Chemistry Chemical Physics, 19 (36), p. 24493–24504, 2017. @article{Martin:2017a, title = {Ultrafast flavin photoreduction in an oxidized animal (6-4) photolyase through an unconventional tryptophan tetrad}, author = {P R Martin and F Lacombat and A Espagne and N Dozova and P Plaza and J Yamamoto and P M\"{u}ller and K Brettel and A De La Lande}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029817108&doi=10.1039%2fc7cp04555g&partnerID=40&md5=b5966e02f7c4f4fa9b385f15647311c3}, doi = {10.1039/c7cp04555g}, year = {2017}, date = {2017-01-01}, journal = {Physical Chemistry Chemical Physics}, volume = {19}, number = {36}, pages = {24493--24504}, abstract = {Photolyases are flavoenzymes repairing UV-induced lesions in DNA, which may be activated by a photoreduction of their FAD cofactor. In most photolyases, this photoreduction proceeds by electron transfer along a chain of three tryptophan (Trp) residues, connecting the flavin to the protein surface. Much less studied, animal (6-4) photolyases (repairing pyrimidine-pyrimidone (6-4) photoproducts) are particularly interesting as they were recently shown to have a longer electron transfer chain, counting four Trp residues. Using femtosecond polarized transient absorption spectroscopy, we performed a detailed analysis of the photoactivation reaction in the (6-4) photolyase of Xenopus laevis with oxidized FAD. We showed that the excited flavin is very quickly reduced (∼0.5 ps) by a nearby tryptophan residue, yielding FAD•- and WH•+ radicals. Subsequent kinetic steps in the picosecond regime were assigned to the migration of the positive charge along the Trp tetrad, in competition with charge recombination. We propose that the positive charge is actually delocalized over various Trp residues during most of the dynamics and that charge recombination essentially occurs through the proximal tryptophanyl radical. Oxidation of the fourth tryptophan is thought to be reached about as fast as that of the third one (∼40 ps), based on a comparison with a mutant protein lacking the distal Trp, implying ultrafast electron transfer between these two residues. This unusual mechanism sheds light on the rich diversity of electron transfer pathways found in various photolyases, and evolution-related cryptochromes alike. © the Owner Societies 2017.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Photolyases are flavoenzymes repairing UV-induced lesions in DNA, which may be activated by a photoreduction of their FAD cofactor. In most photolyases, this photoreduction proceeds by electron transfer along a chain of three tryptophan (Trp) residues, connecting the flavin to the protein surface. Much less studied, animal (6-4) photolyases (repairing pyrimidine-pyrimidone (6-4) photoproducts) are particularly interesting as they were recently shown to have a longer electron transfer chain, counting four Trp residues. Using femtosecond polarized transient absorption spectroscopy, we performed a detailed analysis of the photoactivation reaction in the (6-4) photolyase of Xenopus laevis with oxidized FAD. We showed that the excited flavin is very quickly reduced (∼0.5 ps) by a nearby tryptophan residue, yielding FAD•- and WH•+ radicals. Subsequent kinetic steps in the picosecond regime were assigned to the migration of the positive charge along the Trp tetrad, in competition with charge recombination. We propose that the positive charge is actually delocalized over various Trp residues during most of the dynamics and that charge recombination essentially occurs through the proximal tryptophanyl radical. Oxidation of the fourth tryptophan is thought to be reached about as fast as that of the third one (∼40 ps), based on a comparison with a mutant protein lacking the distal Trp, implying ultrafast electron transfer between these two residues. This unusual mechanism sheds light on the rich diversity of electron transfer pathways found in various photolyases, and evolution-related cryptochromes alike. © the Owner Societies 2017. |
2016 |
Aggregation of Antibody Drug Conjugates at Room Temperature: SAXS and Light Scattering Evidence for Colloidal Instability of a Specific Subpopulation Article de journal B Frka-Petesic; D Zanchi; N Martin; S Carayon; S Huille; C Tribet Langmuir, 32 (19), p. 4848–4861, 2016. @article{Frka-Petesic:2016, title = {Aggregation of Antibody Drug Conjugates at Room Temperature: SAXS and Light Scattering Evidence for Colloidal Instability of a Specific Subpopulation}, author = {B Frka-Petesic and D Zanchi and N Martin and S Carayon and S Huille and C Tribet}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84969780587&doi=10.1021%2facs.langmuir.6b00653&partnerID=40&md5=d0b5c51dcec5e8d91ca097bb1878f7f9}, doi = {10.1021/acs.langmuir.6b00653}, year = {2016}, date = {2016-01-01}, journal = {Langmuir}, volume = {32}, number = {19}, pages = {4848--4861}, abstract = {Coupling a hydrophobic drug onto monoclonal antibodies via lysine residues is a common route to prepare antibody-drug conjugates (ADC), a promising class of biotherapeutics. But a few chemical modifications on protein surface often increase aggregation propensity, without a clear understanding of the aggregation mechanisms at stake (loss of colloidal stability, self-assemblies, denaturation, etc.), and the statistical nature of conjugation introduces polydispersity in the ADC population, which raises questions on whether the whole ADC population becomes unstable. To characterize the average interactions between ADC, we monitored small-angle X-ray scattering in solutions of monoclonal IgG1 human antibody drug conjugate, with average degree of conjugation of 0, 2, or 3 drug molecules per protein. To characterize stability, we studied the kinetics of aggregation at room temperature. The intrinsic Fuchs stability ratio of the ADC was estimated from the variation over time of scattered light intensity and hydrodynamic radius, in buffers of varying pH, and at diverse sucrose (0% or 10%) and NaCl (0 or 100 mM) concentrations. We show that stable ADC stock solutions became unstable upon pH shift, well below the pH of maximum average attraction between IgGs. Data indicate that aggregation can be ascribed to a fraction of ADC population usually representing less than 30 mol % of the sample. In contrast to the case of (monodisperse) monoclonal antibodies, our results suggest that a poor correlation between stability and average interaction parameters should be expected as a corollary of dispersity of ADC conjugation. In practice, the most unstable fraction of the ADC population can be removed by filtration, which affects remarkably the apparent stability of the samples. Finally, the lack of correlation between the kinetic stability and variations of the average inter-ADC interactions is tentatively attributed to the uneven nature of charge distributions and the presence of patches on the drug-modified antibodies. © 2016 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Coupling a hydrophobic drug onto monoclonal antibodies via lysine residues is a common route to prepare antibody-drug conjugates (ADC), a promising class of biotherapeutics. But a few chemical modifications on protein surface often increase aggregation propensity, without a clear understanding of the aggregation mechanisms at stake (loss of colloidal stability, self-assemblies, denaturation, etc.), and the statistical nature of conjugation introduces polydispersity in the ADC population, which raises questions on whether the whole ADC population becomes unstable. To characterize the average interactions between ADC, we monitored small-angle X-ray scattering in solutions of monoclonal IgG1 human antibody drug conjugate, with average degree of conjugation of 0, 2, or 3 drug molecules per protein. To characterize stability, we studied the kinetics of aggregation at room temperature. The intrinsic Fuchs stability ratio of the ADC was estimated from the variation over time of scattered light intensity and hydrodynamic radius, in buffers of varying pH, and at diverse sucrose (0% or 10%) and NaCl (0 or 100 mM) concentrations. We show that stable ADC stock solutions became unstable upon pH shift, well below the pH of maximum average attraction between IgGs. Data indicate that aggregation can be ascribed to a fraction of ADC population usually representing less than 30 mol % of the sample. In contrast to the case of (monodisperse) monoclonal antibodies, our results suggest that a poor correlation between stability and average interaction parameters should be expected as a corollary of dispersity of ADC conjugation. In practice, the most unstable fraction of the ADC population can be removed by filtration, which affects remarkably the apparent stability of the samples. Finally, the lack of correlation between the kinetic stability and variations of the average inter-ADC interactions is tentatively attributed to the uneven nature of charge distributions and the presence of patches on the drug-modified antibodies. © 2016 American Chemical Society. |
Astrocyte-derived adenosine is central to the hypnogenic effect of glucose Article de journal E Scharbarg; M Daenens; F Lemaître; H Geoffroy; M Guille-Collignon; T Gallopin; A Rancillac Scientific Reports, 6 , 2016. @article{Scharbarg:2016, title = {Astrocyte-derived adenosine is central to the hypnogenic effect of glucose}, author = {E Scharbarg and M Daenens and F Lema\^{i}tre and H Geoffroy and M Guille-Collignon and T Gallopin and A Rancillac}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84954456013&doi=10.1038%2fsrep19107&partnerID=40&md5=e785b2e364698aba76cea9c2cade445e}, doi = {10.1038/srep19107}, year = {2016}, date = {2016-01-01}, journal = {Scientific Reports}, volume = {6}, abstract = {Sleep has been hypothesised to maintain a close relationship with metabolism. Here we focus on the brain structure that triggers slow-wave sleep, the ventrolateral preoptic nucleus (VLPO), to explore the cellular and molecular signalling pathways recruited by an increase in glucose concentration. We used infrared videomicroscopy on ex vivo brain slices to establish that glucose induces vasodilations specifically in the VLPO via the astrocytic release of adenosine. Real-time detection by in situ purine biosensors further revealed that the adenosine level doubles in response to glucose, and triples during the wakefulness period. Finally, patch-clamp recordings uncovered the depolarizing effect of adenosine and its A2A receptor agonist, CGS-21680, on sleep-promoting VLPO neurons. Altogether, our results provide new insights into the metabolically driven release of adenosine. We hypothesise that adenosine adjusts the local energy supply to local neuronal activity in response to glucose. This pathway could contribute to sleep-wake transition and sleep intensity.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Sleep has been hypothesised to maintain a close relationship with metabolism. Here we focus on the brain structure that triggers slow-wave sleep, the ventrolateral preoptic nucleus (VLPO), to explore the cellular and molecular signalling pathways recruited by an increase in glucose concentration. We used infrared videomicroscopy on ex vivo brain slices to establish that glucose induces vasodilations specifically in the VLPO via the astrocytic release of adenosine. Real-time detection by in situ purine biosensors further revealed that the adenosine level doubles in response to glucose, and triples during the wakefulness period. Finally, patch-clamp recordings uncovered the depolarizing effect of adenosine and its A2A receptor agonist, CGS-21680, on sleep-promoting VLPO neurons. Altogether, our results provide new insights into the metabolically driven release of adenosine. We hypothesise that adenosine adjusts the local energy supply to local neuronal activity in response to glucose. This pathway could contribute to sleep-wake transition and sleep intensity. |
Design and characterization of red fluorogenic push-pull chromophores holding great potential for bioimaging and biosensing Article de journal C Li; M -A Plamont; I Aujard; T Le Saux; L Jullien; A Gautier Organic and Biomolecular Chemistry, 14 (39), p. 9253–9261, 2016. @article{Li:2016, title = {Design and characterization of red fluorogenic push-pull chromophores holding great potential for bioimaging and biosensing}, author = {C Li and M -A Plamont and I Aujard and T Le Saux and L Jullien and A Gautier}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84990182453&doi=10.1039%2fc6ob01612j&partnerID=40&md5=7cea2c6d4aeeeef91e6a3a5bd0d6b5ad}, doi = {10.1039/c6ob01612j}, year = {2016}, date = {2016-01-01}, journal = {Organic and Biomolecular Chemistry}, volume = {14}, number = {39}, pages = {9253--9261}, abstract = {Fluorogenic chromophores have been used recently for fluorescence reporting and biosensing. Their ability to turn on upon specific interaction with a given target has been exploited in particular for the design of fluorogen-based reporters enabling biomolecule labeling and imaging. In this paper, we report the development and exhaustive characterization of a new family of red fluorogenic push-pull chromophores, holding great potential for the development of fluorogen-based reporters or intracellular fluorogenic markers. The proposed methodology is generic and should find general applicability in the discovery of new fluorogenic dyes suitable for the design of fluorogen-based reporters and biosensors. © The Royal Society of Chemistry 2016.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Fluorogenic chromophores have been used recently for fluorescence reporting and biosensing. Their ability to turn on upon specific interaction with a given target has been exploited in particular for the design of fluorogen-based reporters enabling biomolecule labeling and imaging. In this paper, we report the development and exhaustive characterization of a new family of red fluorogenic push-pull chromophores, holding great potential for the development of fluorogen-based reporters or intracellular fluorogenic markers. The proposed methodology is generic and should find general applicability in the discovery of new fluorogenic dyes suitable for the design of fluorogen-based reporters and biosensors. © The Royal Society of Chemistry 2016. |
Excited-state symmetry breaking of linear quadrupolar chromophores: A transient absorption study Article de journal N Dozova; L Ventelon; G Clermont; M Blanchard-Desce; P Plaza Chemical Physics Letters, 664 , p. 56–62, 2016. @article{Dozova:2016, title = {Excited-state symmetry breaking of linear quadrupolar chromophores: A transient absorption study}, author = {N Dozova and L Ventelon and G Clermont and M Blanchard-Desce and P Plaza}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84991648542&doi=10.1016%2fj.cplett.2016.10.020&partnerID=40&md5=93f48fbad7f0a0a40b036bef2e73147a}, doi = {10.1016/j.cplett.2016.10.020}, year = {2016}, date = {2016-01-01}, journal = {Chemical Physics Letters}, volume = {664}, pages = {56--62}, abstract = {The photophysical properties of two highly symmetrical quadrupolar chromophores were studied by both steady-state and transient absorption spectroscopy. Their excited-state behavior is dominated by the solvent-induced Stokes shift of the stimulated-emission band. The origin of this shift is attributed to symmetry breaking that confers a non-vanishing dipole moment to the excited state of both compounds. This dipole moment is large and constant in DMSO, whereas symmetry breaking appears significantly slower and leading to smaller excited-state dipole in toluene. Time-dependant increase of the excited-state dipole moment induced by weak solvation is proposed to explain the results in toluene. © 2016 Elsevier B.V.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The photophysical properties of two highly symmetrical quadrupolar chromophores were studied by both steady-state and transient absorption spectroscopy. Their excited-state behavior is dominated by the solvent-induced Stokes shift of the stimulated-emission band. The origin of this shift is attributed to symmetry breaking that confers a non-vanishing dipole moment to the excited state of both compounds. This dipole moment is large and constant in DMSO, whereas symmetry breaking appears significantly slower and leading to smaller excited-state dipole in toluene. Time-dependant increase of the excited-state dipole moment induced by weak solvation is proposed to explain the results in toluene. © 2016 Elsevier B.V. |
FRAP to Characterize Molecular Diffusion and Interaction in Various Membrane Environments Article de journal Frederic Pincet; Vladimir Adrien; Rong Yang; Jerome Delacotte; James E Rothman; Wladimir Urbach; David Tareste Plos One, 11 (7), p. e0158457, 2016, ISSN: 1932-6203, (WOS:000379811500020). @article{Pincet:2016, title = {FRAP to Characterize Molecular Diffusion and Interaction in Various Membrane Environments}, author = {Frederic Pincet and Vladimir Adrien and Rong Yang and Jerome Delacotte and James E Rothman and Wladimir Urbach and David Tareste}, doi = {10.1371/journal.pone.0158457}, issn = {1932-6203}, year = {2016}, date = {2016-01-01}, journal = {Plos One}, volume = {11}, number = {7}, pages = {e0158457}, abstract = {Fluorescence recovery after photobleaching (FRAP) is a standard method used to study the dynamics of lipids and proteins in artificial and cellular membrane systems. The advent of confocal microscopy two decades ago has made quantitative FRAP easily available to most laboratories. Usually, a single bleaching pattern/area is used and the corresponding recovery time is assumed to directly provide a diffusion coefficient, although this is only true in the case of unrestricted Brownian motion. Here, we propose some general guidelines to perform FRAP experiments under a confocal microscope with different bleaching patterns and area, allowing the experimentalist to establish whether the molecules undergo Brownian motion (free diffusion) or whether they have restricted or directed movements. Using in silico simulations of FRAP measurements, we further indicate the data acquisition criteria that have to be verified in order to obtain accurate values for the diffusion coefficient and to be able to distinguish between different diffusive species. Using this approach, we compare the behavior of lipids in three different membrane platforms (supported lipid bilayers, giant liposomes and sponge phases), and we demonstrate that FRAP measurements are consistent with results obtained using other techniques such as Fluorescence Correlation Spectroscopy (FCS) or Single Particle Tracking (SPT). Finally, we apply this method to show that the presence of the synaptic protein Munc 18-1 inhibits the interaction between the synaptic vesicle SNARE protein, VAMP2, and its partner from the plasma membrane, Syn1A.}, note = {WOS:000379811500020}, keywords = {}, pubstate = {published}, tppubtype = {article} } Fluorescence recovery after photobleaching (FRAP) is a standard method used to study the dynamics of lipids and proteins in artificial and cellular membrane systems. The advent of confocal microscopy two decades ago has made quantitative FRAP easily available to most laboratories. Usually, a single bleaching pattern/area is used and the corresponding recovery time is assumed to directly provide a diffusion coefficient, although this is only true in the case of unrestricted Brownian motion. Here, we propose some general guidelines to perform FRAP experiments under a confocal microscope with different bleaching patterns and area, allowing the experimentalist to establish whether the molecules undergo Brownian motion (free diffusion) or whether they have restricted or directed movements. Using in silico simulations of FRAP measurements, we further indicate the data acquisition criteria that have to be verified in order to obtain accurate values for the diffusion coefficient and to be able to distinguish between different diffusive species. Using this approach, we compare the behavior of lipids in three different membrane platforms (supported lipid bilayers, giant liposomes and sponge phases), and we demonstrate that FRAP measurements are consistent with results obtained using other techniques such as Fluorescence Correlation Spectroscopy (FCS) or Single Particle Tracking (SPT). Finally, we apply this method to show that the presence of the synaptic protein Munc 18-1 inhibits the interaction between the synaptic vesicle SNARE protein, VAMP2, and its partner from the plasma membrane, Syn1A. |
Kinetics of Photocontrollable Micelles: Light-Induced Self-Assembly and Disassembly of Azobenzene-Based Surfactants Revealed by TR-SAXS Article de journal R Lund; G Brun; E Chevallier; T Narayanan; C Tribet Langmuir, 32 (11), p. 2539–2548, 2016. @article{Lund:2016, title = {Kinetics of Photocontrollable Micelles: Light-Induced Self-Assembly and Disassembly of Azobenzene-Based Surfactants Revealed by TR-SAXS}, author = {R Lund and G Brun and E Chevallier and T Narayanan and C Tribet}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962194768&doi=10.1021%2facs.langmuir.5b04711&partnerID=40&md5=58ff1fd601a8b32f09cccc95ab611dd8}, doi = {10.1021/acs.langmuir.5b04711}, year = {2016}, date = {2016-01-01}, journal = {Langmuir}, volume = {32}, number = {11}, pages = {2539--2548}, abstract = {The kinetics of micelles involving photosensitive surfactants is still not well understood. In this work, we unravel the mechanistic pathways involved in the micelle formation and dissolution of photocontrollable micelles. We focus on the fast self-assembly processes of photosensitive cationic azobenzene-containing surfactants (AzoTMA) that display a change in hydrophobicity induced by a reversible cis-trans conformational transition upon exposure to light. By combining both in situ time-resolved small-angle X-ray scattering (SAXS) and light scattering, we characterized the detailed structure and phase behavior of AzoTMA in mixtures of water and dimethylformamide (DMF). Time-resolved synchrotron SAXS with monochromatic light as a trigger enabled us to observe the nonequilibrium formation and dissolution process of micelles (demicellization) directly on the nanoscale with a time resolution starting from milliseconds. The structural results show that in pure water UV-light illumination leads to a 12% reduction of the aggregation number of the micelles and more than a 50% increase in the critical micelle concentration (CMC). Close to the CMC, adjusted by the addition of DMF, UV light illumination leads to a complete dissolution of the micelles, while shining blue light reverses the process and leads to the reformation of micelles. The UV-triggered dissolution follows a two-step mechanism; the first and rapid (second time scale) release of unimers is followed by a slower decomposition of the micelles (over tens of seconds) as a result of an increase in temperature due to optical absorption. Similarly, the reverse process, i.e., micelle formation, occurs rapidly upon photoconversion to trans conformers under blue light, and micelles are disrupted at long exposure time due to the optical absorption and corresponding increase in temperature. Interestingly, the coexistence of unimers with regular micelles is found at all times, and no other transient assemblies could be detected by SAXS. © 2016 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The kinetics of micelles involving photosensitive surfactants is still not well understood. In this work, we unravel the mechanistic pathways involved in the micelle formation and dissolution of photocontrollable micelles. We focus on the fast self-assembly processes of photosensitive cationic azobenzene-containing surfactants (AzoTMA) that display a change in hydrophobicity induced by a reversible cis-trans conformational transition upon exposure to light. By combining both in situ time-resolved small-angle X-ray scattering (SAXS) and light scattering, we characterized the detailed structure and phase behavior of AzoTMA in mixtures of water and dimethylformamide (DMF). Time-resolved synchrotron SAXS with monochromatic light as a trigger enabled us to observe the nonequilibrium formation and dissolution process of micelles (demicellization) directly on the nanoscale with a time resolution starting from milliseconds. The structural results show that in pure water UV-light illumination leads to a 12% reduction of the aggregation number of the micelles and more than a 50% increase in the critical micelle concentration (CMC). Close to the CMC, adjusted by the addition of DMF, UV light illumination leads to a complete dissolution of the micelles, while shining blue light reverses the process and leads to the reformation of micelles. The UV-triggered dissolution follows a two-step mechanism; the first and rapid (second time scale) release of unimers is followed by a slower decomposition of the micelles (over tens of seconds) as a result of an increase in temperature due to optical absorption. Similarly, the reverse process, i.e., micelle formation, occurs rapidly upon photoconversion to trans conformers under blue light, and micelles are disrupted at long exposure time due to the optical absorption and corresponding increase in temperature. Interestingly, the coexistence of unimers with regular micelles is found at all times, and no other transient assemblies could be detected by SAXS. © 2016 American Chemical Society. |
Kinetics of Reactive Modules Adds Discriminative Dimensions for Selective Cell Imaging Article de journal J Quérard; T Le Saux; A Gautier; D Alcor; V Croquette; A Lemarchand; C Gosse; L Jullien ChemPhysChem, 17 (10), p. 1396–1413, 2016. @article{Querard:2016, title = {Kinetics of Reactive Modules Adds Discriminative Dimensions for Selective Cell Imaging}, author = {J Qu\'{e}rard and T Le Saux and A Gautier and D Alcor and V Croquette and A Lemarchand and C Gosse and L Jullien}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957539317&doi=10.1002%2fcphc.201500987&partnerID=40&md5=4a514250af842ae7697b695eb73769fb}, doi = {10.1002/cphc.201500987}, year = {2016}, date = {2016-01-01}, journal = {ChemPhysChem}, volume = {17}, number = {10}, pages = {1396--1413}, abstract = {Living cells are chemical mixtures of exceptional interest and significance, whose investigation requires the development of powerful analytical tools fulfilling the demanding constraints resulting from their singular features. In particular, multiplexed observation of a large number of molecular targets with high spatiotemporal resolution appears highly desirable. One attractive road to address this analytical challenge relies on engaging the targets in reactions and exploiting the rich kinetic signature of the resulting reactive module, which originates from its topology and its rate constants. This review explores the various facets of this promising strategy. We first emphasize the singularity of the content of a living cell as a chemical mixture and suggest that its multiplexed observation is significant and timely. Then, we show that exploiting the kinetics of analytical processes is relevant to selectively detect a given analyte: upon perturbing the system, the kinetic window associated to response read-out has to be matched with that of the targeted reactive module. Eventually, we introduce the state-of-the-art of cell imaging exploiting protocols based on reaction kinetics and draw some promising perspectives. Live recording: In living cells, the multiplexed observation of a large number of targets has recently emerged as a desirable goal. To address this challenge, an attractive road relies on engaging the targets in reactions and exploiting the kinetic signature of the resulting reactive module. This review explores the facets of this strategy and draw some promising perspectives. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Living cells are chemical mixtures of exceptional interest and significance, whose investigation requires the development of powerful analytical tools fulfilling the demanding constraints resulting from their singular features. In particular, multiplexed observation of a large number of molecular targets with high spatiotemporal resolution appears highly desirable. One attractive road to address this analytical challenge relies on engaging the targets in reactions and exploiting the rich kinetic signature of the resulting reactive module, which originates from its topology and its rate constants. This review explores the various facets of this promising strategy. We first emphasize the singularity of the content of a living cell as a chemical mixture and suggest that its multiplexed observation is significant and timely. Then, we show that exploiting the kinetics of analytical processes is relevant to selectively detect a given analyte: upon perturbing the system, the kinetic window associated to response read-out has to be matched with that of the targeted reactive module. Eventually, we introduce the state-of-the-art of cell imaging exploiting protocols based on reaction kinetics and draw some promising perspectives. Live recording: In living cells, the multiplexed observation of a large number of targets has recently emerged as a desirable goal. To address this challenge, an attractive road relies on engaging the targets in reactions and exploiting the kinetic signature of the resulting reactive module. This review explores the facets of this strategy and draw some promising perspectives. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. |
Mechanism and analyses for extracting photosynthetic electrons using exogenous quinones-what makes a good extraction pathway? Article de journal G Longatte; F Rappaport; F -A Wollman; M Guille-Collignon; F Lemaître Photochemical and Photobiological Sciences, 15 (8), p. 969–979, 2016. @article{Longatte:2016, title = {Mechanism and analyses for extracting photosynthetic electrons using exogenous quinones-what makes a good extraction pathway?}, author = {G Longatte and F Rappaport and F -A Wollman and M Guille-Collignon and F Lema\^{i}tre}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982703184&doi=10.1039%2fc6pp00076b&partnerID=40&md5=bf03d01f7c5b19ff550d5b9f76d49eb9}, doi = {10.1039/c6pp00076b}, year = {2016}, date = {2016-01-01}, journal = {Photochemical and Photobiological Sciences}, volume = {15}, number = {8}, pages = {969--979}, abstract = {Plants or algae take many benefits from oxygenic photosynthesis by converting solar energy into chemical energy through the synthesis of carbohydrates from carbon dioxide and water. However, the overall yield of this process is rather low (about 4% of the total energy available from sunlight is converted into chemical energy). This is the principal reason why recently many studies have been devoted to extraction of photosynthetic electrons in order to produce a sustainable electric current. Practically, the electron transfer occurs between the photosynthetic organism and an electrode and can be assisted by an exogenous mediator, mainly a quinone. In this regard, we recently reported on a method involving fluorescence measurements to estimate the ability of different quinones to extract photosynthetic electrons from a mutant of Chlamydomonas reinhardtii. In the present work, we used the same kind of methodology to establish a zone diagram for predicting the most suitable experimental conditions to extract photoelectrons from intact algae (quinone concentration and light intensity) as a function of the purpose of the study. This will provide further insights into the extraction mechanism of photosynthetic electrons using exogenous quinones. Indeed fluorescence measurements allowed us to model the capacity of photosynthetic algae to donate electrons to an exogenous quinone by considering a numerical parameter called "open center ratio" which is related to the Photosystem II acceptor redox state. Then, using it as a proxy for investigating the extraction of photosynthetic electrons by means of an exogenous quinone, 2,6-DCBQ, we suggested an extraction mechanism that was globally found consistent with the experimentally extracted parameters. © The Royal Society of Chemistry and Owner Societies 2016.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Plants or algae take many benefits from oxygenic photosynthesis by converting solar energy into chemical energy through the synthesis of carbohydrates from carbon dioxide and water. However, the overall yield of this process is rather low (about 4% of the total energy available from sunlight is converted into chemical energy). This is the principal reason why recently many studies have been devoted to extraction of photosynthetic electrons in order to produce a sustainable electric current. Practically, the electron transfer occurs between the photosynthetic organism and an electrode and can be assisted by an exogenous mediator, mainly a quinone. In this regard, we recently reported on a method involving fluorescence measurements to estimate the ability of different quinones to extract photosynthetic electrons from a mutant of Chlamydomonas reinhardtii. In the present work, we used the same kind of methodology to establish a zone diagram for predicting the most suitable experimental conditions to extract photoelectrons from intact algae (quinone concentration and light intensity) as a function of the purpose of the study. This will provide further insights into the extraction mechanism of photosynthetic electrons using exogenous quinones. Indeed fluorescence measurements allowed us to model the capacity of photosynthetic algae to donate electrons to an exogenous quinone by considering a numerical parameter called "open center ratio" which is related to the Photosystem II acceptor redox state. Then, using it as a proxy for investigating the extraction of photosynthetic electrons by means of an exogenous quinone, 2,6-DCBQ, we suggested an extraction mechanism that was globally found consistent with the experimentally extracted parameters. © The Royal Society of Chemistry and Owner Societies 2016. |
More Transparency in BioAnalysis of Exocytosis: Coupling of Electrochemistry and Fluorescence Microscopy at ITO Electrodes Book Chapter Xiaoqing Liu; Damien Quinton; Lihui Hu; Christian Amatore; Jerome Delacotte; Frederic Lemaitre; Manon Guille-Collignon Raspaud, E; Marliere, C; Regeard, C; Cornut, R; MealletRenault, R (Ed.): Electro-Activity of Biological Systems, 6 , 2016, (Times Cited: 0 International and Multidisciplinary Workshop on Electro-Activity of Biological Systems (EABS) Nov 18-19, 2015 Paris, FRANCE). @inbook{, title = {More Transparency in BioAnalysis of Exocytosis: Coupling of Electrochemistry and Fluorescence Microscopy at ITO Electrodes}, author = {Xiaoqing Liu and Damien Quinton and Lihui Hu and Christian Amatore and Jerome Delacotte and Frederic Lemaitre and Manon Guille-Collignon}, editor = {E Raspaud and C Marliere and C Regeard and R Cornut and R MealletRenault}, year = {2016}, date = {2016-01-01}, booktitle = {Electro-Activity of Biological Systems}, volume = {6}, series = {BIO Web of Conferences}, note = {Times Cited: 0 International and Multidisciplinary Workshop on Electro-Activity of Biological Systems (EABS) Nov 18-19, 2015 Paris, FRANCE}, keywords = {}, pubstate = {published}, tppubtype = {inbook} } |
Multi-chambers Microsystem for Simultaneous and Direct Electrochemical Detection of Reactive Oxygen and Nitrogen Species Released by Cell Populations Article de journal Y Li; A Meunier; R Fulcrand; C Sella; C Amatore; L Thouin; F Lemaître; M Guille-Collignon Electroanalysis, 28 (8), p. 1865–1872, 2016. @article{Li:2016a, title = {Multi-chambers Microsystem for Simultaneous and Direct Electrochemical Detection of Reactive Oxygen and Nitrogen Species Released by Cell Populations}, author = {Y Li and A Meunier and R Fulcrand and C Sella and C Amatore and L Thouin and F Lema\^{i}tre and M Guille-Collignon}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960146089&doi=10.1002%2felan.201501157&partnerID=40&md5=31cc094d742b25352edb1219bc260f3c}, doi = {10.1002/elan.201501157}, year = {2016}, date = {2016-01-01}, journal = {Electroanalysis}, volume = {28}, number = {8}, pages = {1865--1872}, abstract = {Electrochemical quantification of four reactive oxygen and nitrogen species (e.g., H2O2, ONOO−, NO and NO2 −) emitted from macrophages populations was completed using a four-chambers microchip. This microchip was fabricated from a glass substrate equipped with four sets of microband electrodes. Each set consisted of a platinum-black coated working electrode combined to an Ag/AgCl reference and a Pt counter electrodes. A cover made of polydimethylsiloxane was designed with four wells whose open bottoms fitted over each set. Loading, culture and stimulation of cells were conducted within each well. After stimulation of macrophages by a calcium ionophore, amperometric responses were then monitored using a multipotentiostat to detect one species per well simultaneously. The results showed good reproducibility and were quite consistent with averaged amperometric detections obtained from single cell measurements. This methodology allowed drastically diminishing the number of experiments necessary to reach a statistical significance from n=100\textendash160 experiments required for single cell detection compared to n=5 experiments to obtain the mean behavior of the cell population. This work demonstrated that this simple and versatile microchip could be used for quantification of species in oxidative stress investigations on cell populations as well as a complementary tool to compare behaviors between single cell and cell population for investigations involving many experimental variables. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim}, keywords = {}, pubstate = {published}, tppubtype = {article} } Electrochemical quantification of four reactive oxygen and nitrogen species (e.g., H2O2, ONOO−, NO and NO2 −) emitted from macrophages populations was completed using a four-chambers microchip. This microchip was fabricated from a glass substrate equipped with four sets of microband electrodes. Each set consisted of a platinum-black coated working electrode combined to an Ag/AgCl reference and a Pt counter electrodes. A cover made of polydimethylsiloxane was designed with four wells whose open bottoms fitted over each set. Loading, culture and stimulation of cells were conducted within each well. After stimulation of macrophages by a calcium ionophore, amperometric responses were then monitored using a multipotentiostat to detect one species per well simultaneously. The results showed good reproducibility and were quite consistent with averaged amperometric detections obtained from single cell measurements. This methodology allowed drastically diminishing the number of experiments necessary to reach a statistical significance from n=100–160 experiments required for single cell detection compared to n=5 experiments to obtain the mean behavior of the cell population. This work demonstrated that this simple and versatile microchip could be used for quantification of species in oxidative stress investigations on cell populations as well as a complementary tool to compare behaviors between single cell and cell population for investigations involving many experimental variables. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim |
Real Time Monitoring of Peroxynitrite by Stimulation of Macrophages with Ultramicroelectrodes Book Chapter Christian Amatore; Manon Guille-Collignon; Frederic Lemaitre Peteu, S F; Szunerits, S; Bayachou, M (Ed.): Peroxynitrite Detection in Biological Media: Challenges and Advances, 7 , p. 96-120, 2016, (Times Cited: 0). @inbook{, title = {Real Time Monitoring of Peroxynitrite by Stimulation of Macrophages with Ultramicroelectrodes}, author = {Christian Amatore and Manon Guille-Collignon and Frederic Lemaitre}, editor = {S F Peteu and S Szunerits and M Bayachou}, year = {2016}, date = {2016-01-01}, booktitle = {Peroxynitrite Detection in Biological Media: Challenges and Advances}, volume = {7}, pages = {96-120}, series = {RSC Detection Science Series}, note = {Times Cited: 0}, keywords = {}, pubstate = {published}, tppubtype = {inbook} } |
Revisiting the Complex Osmocene Electro-Oxidation Mechanism Article de journal F Chau; C Amatore; E Labbé; O Buriez Electrochimica Acta, 212 , p. 973–978, 2016. @article{Chau:2016, title = {Revisiting the Complex Osmocene Electro-Oxidation Mechanism}, author = {F Chau and C Amatore and E Labb\'{e} and O Buriez}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978646014&doi=10.1016%2fj.electacta.2016.07.082&partnerID=40&md5=57bf46e24409b5ec314632cff4c66c9a}, doi = {10.1016/j.electacta.2016.07.082}, year = {2016}, date = {2016-01-01}, journal = {Electrochimica Acta}, volume = {212}, pages = {973--978}, abstract = {The electrochemical oxidation of osmocene was investigated in dichloromethane (DCM) and acetonitrile (MeCN) in the presence of various electrolyte anions ([BF4]−, [PF6]−, and [B(C6F5)4]− (TFAB)). The results showed that the reactivity of the electrogenerated osmocenium cation was dramatically affected by the coordinating properties of the electrolyte anion and the donor strength of the solvent. Cyclic voltammetry allowed the characterization of transient species and led to rationalization of some controversial mechanistic conclusions published before, which were in fact all correct, but referred to different conditions. Notably, the electrochemical signature of the dimer dication [Cp2Os]2 2+ that appears as a crucial species to explain the voltammetric oxidative pattern of osmocene was detected for the first time. © 2016 Elsevier Ltd}, keywords = {}, pubstate = {published}, tppubtype = {article} } The electrochemical oxidation of osmocene was investigated in dichloromethane (DCM) and acetonitrile (MeCN) in the presence of various electrolyte anions ([BF4]−, [PF6]−, and [B(C6F5)4]− (TFAB)). The results showed that the reactivity of the electrogenerated osmocenium cation was dramatically affected by the coordinating properties of the electrolyte anion and the donor strength of the solvent. Cyclic voltammetry allowed the characterization of transient species and led to rationalization of some controversial mechanistic conclusions published before, which were in fact all correct, but referred to different conditions. Notably, the electrochemical signature of the dimer dication [Cp2Os]2 2+ that appears as a crucial species to explain the voltammetric oxidative pattern of osmocene was detected for the first time. © 2016 Elsevier Ltd |
Small Fluorescence-Activating and Absorption-Shifting Tag for Tunable Protein Imaging in Vivo Article de journal Marie-Aude Plamont; Emmanuelle Billon-Denis; Sylvie Maurin; Carole Gauron; Frederico M Pimenta; Christian G Specht; Jian Shi; Jérôme Querard; Buyan Pan; Julien Rossignol; Karine Moncoq; Nelly Morellet; Michel Volovitch; Ewen Lescop; Yong Chen; Antoine Triller; Sophie Vriz; Thomas Le Saux; Ludovic Jullien; Arnaud Gautier Proceedings of the National Academy of Sciences, 113 (3), p. 497, 2016. @article{RN50, title = {Small Fluorescence-Activating and Absorption-Shifting Tag for Tunable Protein Imaging in Vivo}, author = {Marie-Aude Plamont and Emmanuelle {Billon-Denis} and Sylvie Maurin and Carole Gauron and Frederico M Pimenta and Christian G Specht and Jian Shi and J\'{e}r\^{o}me Querard and Buyan Pan and Julien Rossignol and Karine Moncoq and Nelly Morellet and Michel Volovitch and Ewen Lescop and Yong Chen and Antoine Triller and Sophie Vriz and Thomas Le Saux and Ludovic Jullien and Arnaud Gautier}, doi = {10.1073/pnas.1513094113}, year = {2016}, date = {2016-01-01}, journal = {Proceedings of the National Academy of Sciences}, volume = {113}, number = {3}, pages = {497}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Small fluorescence-activating and absorption-shifting tag for tunable protein imaging in vivo Article de journal Marie-Aude Plamont; Emmanuelle Billon-Denis; Sylvie Maurin; Carole Gauron; Frederico M Pimenta; Christian G Specht; Jian Shi; Jér^ome Quérard; Buyan Pan; Julien Rossignol; others Proceedings of the National Academy of Sciences, 113 (3), p. 497–502, 2016. @article{plamont2016small, title = {Small fluorescence-activating and absorption-shifting tag for tunable protein imaging in vivo}, author = {Marie-Aude Plamont and Emmanuelle Billon-Denis and Sylvie Maurin and Carole Gauron and Frederico M Pimenta and Christian G Specht and Jian Shi and J\'{e}r{^o}me Qu\'{e}rard and Buyan Pan and Julien Rossignol and others}, year = {2016}, date = {2016-01-01}, journal = {Proceedings of the National Academy of Sciences}, volume = {113}, number = {3}, pages = {497--502}, publisher = {National Academy of Sciences}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
J Malinge; F Mousseau; D Zanchi; G Brun; C Tribet; E Marie Journal of Colloid and Interface Science, 461 , p. 50–55, 2016. @article{Malinge:2016, title = {Tailored stimuli-responsive interaction between particles adjusted by straightforward adsorption of mixed layers of Poly(lysine)-g-PEG and Poly(lysine)-g-PNIPAM on anionic beads}, author = {J Malinge and F Mousseau and D Zanchi and G Brun and C Tribet and E Marie}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84941966040&doi=10.1016%2fj.jcis.2015.09.016&partnerID=40&md5=5f2229f36d05f3279fd26b0c88f46406}, doi = {10.1016/j.jcis.2015.09.016}, year = {2016}, date = {2016-01-01}, journal = {Journal of Colloid and Interface Science}, volume = {461}, pages = {50--55}, abstract = {We report a simple and versatile method to functionalize anionic colloid particles and control particle solubility. Poly(lysine)-based copolymers (PLL) grafted with polyethylene oxide (PLL-g-PEG) or poly(N-isopropylacrylamide) (PLL-g-PNIPAM) spontaneously adsorb on bare beads dispersed in aqueous solutions of the copolymers. The final composition of the mixed ad-layers formed (i.e. PEG/PNIPAM ratio) was adjusted by the polymer concentrations in solutions. While the (PLL-g-PEG)-coated particles were stable in a wide range of temperature, the presence of PLL-g-PNIPAM in the outer layer provided a reversible temperature-triggered aggregation at 32 ± 1. °C. In the range of PNIPAM fraction going from 100% (beads fully covered by PLL-g-PNIPAM) down to a threshold 20% weight ratio (with 80% PLL-g-PEG), the particles aggregated rapidly to form micrometer size clusters. Below 20% weight fraction of PLL-g-PNIPAM, the kinetic was drastically lowered. Using PLL derivatives provides a straightforward route allowing to control the fraction of a functional chain (here PNIPAM) deposited on PEGylated particles, and in turn to adjust surface interaction and here the rate of particle-particle aggregation as a function of the density of functional chains. This approach can be generalized to many anionic surfaces onto which PLL is known to adhere tightly, such as glass or silica. © 2015 Elsevier Inc.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We report a simple and versatile method to functionalize anionic colloid particles and control particle solubility. Poly(lysine)-based copolymers (PLL) grafted with polyethylene oxide (PLL-g-PEG) or poly(N-isopropylacrylamide) (PLL-g-PNIPAM) spontaneously adsorb on bare beads dispersed in aqueous solutions of the copolymers. The final composition of the mixed ad-layers formed (i.e. PEG/PNIPAM ratio) was adjusted by the polymer concentrations in solutions. While the (PLL-g-PEG)-coated particles were stable in a wide range of temperature, the presence of PLL-g-PNIPAM in the outer layer provided a reversible temperature-triggered aggregation at 32 ± 1. °C. In the range of PNIPAM fraction going from 100% (beads fully covered by PLL-g-PNIPAM) down to a threshold 20% weight ratio (with 80% PLL-g-PEG), the particles aggregated rapidly to form micrometer size clusters. Below 20% weight fraction of PLL-g-PNIPAM, the kinetic was drastically lowered. Using PLL derivatives provides a straightforward route allowing to control the fraction of a functional chain (here PNIPAM) deposited on PEGylated particles, and in turn to adjust surface interaction and here the rate of particle-particle aggregation as a function of the density of functional chains. This approach can be generalized to many anionic surfaces onto which PLL is known to adhere tightly, such as glass or silica. © 2015 Elsevier Inc. |
Temperature-Switchable Control of Ligand Display on Adlayers of Mixed Poly(Lysine)-g-(PEO) and Poly(Lysine)-g-(Ligand-Modified Poly-N-Isopropylacrylamide) Article de journal F Dalier; F Eghiaian; S Scheuring; E Marie; C Tribet Biomacromolecules, 17 (5), p. 1727-1736, 2016, ISSN: 1525-7797. @article{Dalier:2016, title = {Temperature-Switchable Control of Ligand Display on Adlayers of Mixed Poly(Lysine)-g-(PEO) and Poly(Lysine)-g-(Ligand-Modified Poly-N-Isopropylacrylamide)}, author = {F Dalier and F Eghiaian and S Scheuring and E Marie and C Tribet}, doi = {10.1021/acs.biomac.6b00136}, issn = {1525-7797}, year = {2016}, date = {2016-05-01}, journal = {Biomacromolecules}, volume = {17}, number = {5}, pages = {1727-1736}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Temperature-Switchable Control of Ligand Display on Adlayers of Mixed Poly(Lysine)-g-(PEO) and Poly(Lysine)-g-(Ligand-Modified Poly-N-Isopropylacrylamide) Article de journal F Dalier; F Eghiaian; S Scheuring; E Marie; C Tribet Biomacromolecules, 17 , p. 1727-1736, 2016, ISSN: 1525-7797. @article{RN4d, title = {Temperature-Switchable Control of Ligand Display on Adlayers of Mixed Poly(Lysine)-g-(PEO) and Poly(Lysine)-g-(Ligand-Modified Poly-N-Isopropylacrylamide)}, author = {F Dalier and F Eghiaian and S Scheuring and E Marie and C Tribet}, doi = {10.1021/acs.biomac.6b00136}, issn = {1525-7797}, year = {2016}, date = {2016-01-01}, journal = {Biomacromolecules}, volume = {17}, pages = {1727-1736}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Triggering signaling pathways using F-actin self-organization Article de journal A Colin; L Bonnemay; C Gayrard; J Gautier; Z Gueroui Scientific Reports, 6 , p. 12, 2016, ISSN: 2045-2322. @article{RN20c, title = {Triggering signaling pathways using F-actin self-organization}, author = {A Colin and L Bonnemay and C Gayrard and J Gautier and Z Gueroui}, url = {<Go to ISI>://WOS:000384711000002}, doi = {10.1038/srep34657}, issn = {2045-2322}, year = {2016}, date = {2016-01-01}, journal = {Scientific Reports}, volume = {6}, pages = {12}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Ultrafast Dynamics of a Green Fluorescent Protein Chromophore Analogue: Competition between Excited-State Proton Transfer and Torsional Relaxation Article de journal T Chatterjee; F Lacombat; D Yadav; M Mandal; P Plaza; A Espagne; P K Mandal Journal of Physical Chemistry B, 120 (36), p. 9716–9722, 2016. @article{Chatterjee:2016, title = {Ultrafast Dynamics of a Green Fluorescent Protein Chromophore Analogue: Competition between Excited-State Proton Transfer and Torsional Relaxation}, author = {T Chatterjee and F Lacombat and D Yadav and M Mandal and P Plaza and A Espagne and P K Mandal}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84987847663&doi=10.1021%2facs.jpcb.6b05795&partnerID=40&md5=dbc7a71ee9d3e1a62872f19c1f0c7204}, doi = {10.1021/acs.jpcb.6b05795}, year = {2016}, date = {2016-01-01}, journal = {Journal of Physical Chemistry B}, volume = {120}, number = {36}, pages = {9716--9722}, abstract = {The competition between excited-state proton transfer (ESPT) and torsion plays a central role in the photophysics of fluorescent proteins of the green fluorescent protein (GFP) family and their chromophores. Here, it was investigated in a single GFP chromophore analogue bearing o-hydroxy and p-diethylamino substituents, OHIM. The light-induced dynamics of OHIM was studied by femtosecond transient absorption spectroscopy, at different pH. We found that the photophysics of OHIM is determined by the electron-donating character of the diethylamino group: torsional relaxation dominates when the diethylamino group is neutral, whereas ultrafast ESPT followed by cis/trans isomerization and ground-state reprotonation are observed when the diethylamino group is protonated and therefore inactive as an electron donor. © 2016 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The competition between excited-state proton transfer (ESPT) and torsion plays a central role in the photophysics of fluorescent proteins of the green fluorescent protein (GFP) family and their chromophores. Here, it was investigated in a single GFP chromophore analogue bearing o-hydroxy and p-diethylamino substituents, OHIM. The light-induced dynamics of OHIM was studied by femtosecond transient absorption spectroscopy, at different pH. We found that the photophysics of OHIM is determined by the electron-donating character of the diethylamino group: torsional relaxation dominates when the diethylamino group is neutral, whereas ultrafast ESPT followed by cis/trans isomerization and ground-state reprotonation are observed when the diethylamino group is protonated and therefore inactive as an electron donor. © 2016 American Chemical Society. |
2015 |
Access to new endoperoxide derivatives by electrochemical oxidation of substituted 3-azabicyclo[4.1.0]hept-4-enes Article de journal F Nuter; A K D Dimé; C Chen; L Bounaadja; E Mouray; I Florent; Y Six; O Buriez; A Marinetti; A Voituriez Chemistry - A European Journal, 21 (14), p. 5584–5593, 2015. @article{Nuter:2015, title = {Access to new endoperoxide derivatives by electrochemical oxidation of substituted 3-azabicyclo[4.1.0]hept-4-enes}, author = {F Nuter and A K D Dim\'{e} and C Chen and L Bounaadja and E Mouray and I Florent and Y Six and O Buriez and A Marinetti and A Voituriez}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84925132703&doi=10.1002%2fchem.201406138&partnerID=40&md5=74df69d010145a217a9973a363748bc7}, doi = {10.1002/chem.201406138}, year = {2015}, date = {2015-01-01}, journal = {Chemistry - A European Journal}, volume = {21}, number = {14}, pages = {5584--5593}, abstract = {A series of substituted 3-azabicyclo[4.1.0]hept-4-ene derivatives were prepared and analysed by cyclic voltammetry. Preparative aerobic electrochemical oxidation reactions were then carried out. Three original endoperoxides were isolated, characterised and subjected to antimalarial and cytotoxicity activity assays. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A series of substituted 3-azabicyclo[4.1.0]hept-4-ene derivatives were prepared and analysed by cyclic voltammetry. Preparative aerobic electrochemical oxidation reactions were then carried out. Three original endoperoxides were isolated, characterised and subjected to antimalarial and cytotoxicity activity assays. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. |