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Botet R.,University Paris - Sud | Cabane B.,CNRS Chemistry, Biology and Innovation Laboratory | Goehring L.,Max Planck Institute for Dynamics and Self-Organization | Li J.,Max Planck Institute for Dynamics and Self-Organization | Artzner F.,Rennes Institute of Physics
Faraday Discussions | Year: 2016

A modified version of the Gibbs-ensemble Monte-Carlo method reveals how polydisperse charged colloidal particles can build complex colloidal crystals. It provides general rules that are applicable to this fractionated crystallization that stems from size segregation. It explains the spontaneous formation of complex crystals with very large unit-cells in suspensions of nanoparticles with a broad size distribution. © The Royal Society of Chemistry 2016.


Leman M.,CNRS Gulliver Laboratory | Leman M.,CNRS Chemistry, Biology and Innovation Laboratory | Abouakil F.,CNRS Gulliver Laboratory | Griffiths A.D.,CNRS Chemistry, Biology and Innovation Laboratory | Tabeling P.,CNRS Gulliver Laboratory
Lab on a Chip - Miniaturisation for Chemistry and Biology | Year: 2015

We have built a toolbox of modules for droplet-based microfluidic operations on femtolitre volume droplets. We have demonstrated monodisperse production, sorting, coalescence, splitting, mixing, off-chip incubation and re-injection at high frequencies (up to 3 kHz). We describe the constraints and limitations under which satisfactory performances are obtained, and discuss the physics that controls each operation. For some operations, such as internal mixing, we obtained outstanding performances: for instance, in 75 fL droplets the mixing time was 45 μs, 35-fold faster than previously reported for a droplet microreactor. In practice, in all cases, a level of control comparable to nanolitre or picolitre droplet manipulation was obtained despite the 3 to 6 order of magnitude reduction in droplet volume. Remarkably, all the operations were performed using devices made using standard soft-lithography techniques and PDMS rapid prototyping. We show that femtolitre droplets can be used as microreactors for molecular biology with volumes one billion times smaller than conventional microtitre plate wells: in particular, the Polymerase Chain Reaction (PCR) was shown to work efficiently in 20 fL droplets. © The Royal Society of Chemistry 2015.


Demoulin D.,CNRS Chemistry, Biology and Innovation Laboratory | Carlier M.-F.,French National Center for Scientific Research | Bibette J.,CNRS Chemistry, Biology and Innovation Laboratory | Baudry J.,CNRS Chemistry, Biology and Innovation Laboratory
Proceedings of the National Academy of Sciences of the United States of America | Year: 2014

The actin cytoskeleton has the unique capability of producing pushing forces at the leading edge of motile cells without the implication of molecular motors. This phenomenon has been extensively studied theoretically, and molecular models, including the widely known Brownian ratchet, have been proposed. However, supporting experimental work is lacking, due in part to hardly accessible molecular length scales. We designed an experiment to directly probe the mechanism of force generation in a setup where a population of actin filaments grows against a load applied by magnetic microparticles. The filaments, arranged in stiff bundles by fascin, are constrained to point toward the applied load. In this protrusion-like geometry, we are able to directly measure the velocity of filament elongation and its dependence on force. Using numerical simulations, we provide evidence that our experimental data are consistent with a Brownian ratchet-based model. We further demonstrate the existence of a force regime far below stalling where the mechanical power transduced by the ratcheting filaments to the load is maximal. The actin machinery in migrating cells may tune the number of filaments at the leading edge to work in this force regime. © 2014 National Academy of Sciences. All rights reserved.


Najah M.,CNRS Institute of Science and Supramolecular Engineering | Calbrix R.,CNRS Institute of Science and Supramolecular Engineering | Mahendra-Wijaya I.P.,CNRS Institute of Science and Supramolecular Engineering | Beneyton T.,CNRS Chemistry, Biology and Innovation Laboratory | And 3 more authors.
Chemistry and Biology | Year: 2014

Discovery of microorganisms producing enzymes that can efficiently hydrolyze cellulosic biomass is of great importance for biofuel production. To date, however, only a miniscule fraction of natural biodiversity has been tested because of the relatively low throughput of screening systems and their limitation to screening only culturable microorganisms. Here, we describe an ultra-high-throughput droplet-based microfluidic system that allowed the screening of over 100,000 cells in less than 20 min. Uncultured bacteria from a wheat stubble field were screened directly by compartmentalization of single bacteria in 20 pl droplets containing a fluorogenic cellobiohydrolase substrate. Sorting of droplets based on cellobiohydrolase activity resulted in a bacterial population with 17- and 7-fold higher cellobiohydrolase and endogluconase activity, respectively, and very different taxonomic diversity than when selected for growth on medium containing starch and carboxymethylcellulose as carbon source. © 2014 Elsevier Ltd. All rights reserved.


Cahiez G.,CNRS Paris Research Institute of Chemistry | Moyeux A.,CNRS Paris Research Institute of Chemistry | Moyeux A.,University of Paris 13 | Cossy J.,CNRS Chemistry, Biology and Innovation Laboratory
Advanced Synthesis and Catalysis | Year: 2015

Grignard reagents are probably the best organometallics to develop large-scale eco-friendly cross-couplings compatible with the requirements of sustainable development. This account aims to highlight some reactions having an interesting industrial potential and gives the personal point of view of the authors on some attractive fields of research in this area. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Guerinot A.,CNRS Chemistry, Biology and Innovation Laboratory | Cossy J.,CNRS Chemistry, Biology and Innovation Laboratory
Topics in Current Chemistry | Year: 2016

Over the last decades, iron-catalyzed cross-couplings have emerged as an important tool for the formation of C–C bonds. A wide variety of alkenyl, aryl, and alkyl (pseudo)halides have been coupled to organometallic reagents, the most currently used being Grignard reagents. Particular attention has been devoted to the development of iron catalysts for the functionalization of alkyl halides that are generally challenging substrates in classical cross-couplings. The high functional group tolerance of iron-catalyzed cross-couplings has encouraged organic chemists to use them in the synthesis of bioactive compounds. Even if some points remain obscure, numerous studies have been carried out to investigate the mechanism of iron-catalyzed cross-coupling and several hypotheses have been proposed. © 2016, Springer International Publishing Switzerland.


Hostier T.,CNRS Chemistry, Biology and Innovation Laboratory | Ferey V.,CNRS Chemistry, Biology and Innovation Laboratory | Ricci G.,CNRS Chemistry, Biology and Innovation Laboratory | Gomez Pardo D.,CNRS Chemistry, Biology and Innovation Laboratory | Cossy J.,CNRS Chemistry, Biology and Innovation Laboratory
Organic Letters | Year: 2015

A simple, efficient, and practical metal-free C-H sulfenylation of substituted electron-rich arenes has been developed. This method is highly regioselective, and the corresponding aryl sulfides were obtained in moderate to excellent yields from stable and readily accessible N-(alkylthio)- and N-(arylthio)succinimides at room temperature in the presence of TFA. © 2015 American Chemical Society.


Cossy J.,CNRS Chemistry, Biology and Innovation Laboratory | Guerinot A.,CNRS Chemistry, Biology and Innovation Laboratory
Advances in Heterocyclic Chemistry | Year: 2016

Oxygen-containing heterocycles are ubiquitous in biologically active natural products, which can be a great source of inspiration in drug discovery. Due to the importance of this class of compounds, a myriad of synthetic methods has been developed to access oxygen-containing heterocycles, which are based on two main strategies. The first one involves the formation of a C. O bond of the heterocycle while in the second one, a C. C bond is formed. The recent research in this area aims at developing chemo-, regio-, diastereo-, and enantioselective methods involving catalytic processes. © 2016 Elsevier Inc.


Lafaye K.,CNRS Chemistry, Biology and Innovation Laboratory | Nicolas L.,CNRS Chemistry, Biology and Innovation Laboratory | Guerinot A.,CNRS Chemistry, Biology and Innovation Laboratory | Reymond S.,CNRS Chemistry, Biology and Innovation Laboratory | Cossy J.,CNRS Chemistry, Biology and Innovation Laboratory
Organic Letters | Year: 2014

Cross-metathesis involving N-heteroaromatic olefinic derivatives is disclosed. The introduction of an appropriate substituent on the heteroaromatic ring decreases the Lewis basicity of the nitrogen atom, thus preventing the deactivation of the ruthenium-centered catalyst. The reaction is quite general in terms of both N-heterocycles and olefinic partners. © 2014 American Chemical Society.


Azzouz I.,CNRS Chemistry, Biology and Innovation Laboratory | Essoussi A.,CNRS Chemistry, Biology and Innovation Laboratory | Fleury J.,CNRS Chemistry, Biology and Innovation Laboratory | Haudebourg R.,CNRS Chemistry, Biology and Innovation Laboratory | And 2 more authors.
Journal of Chromatography A | Year: 2015

The preparation conditions of silica monoliths for gas chromatography were investigated. Silica-based monolithic capillary columns based on sol-gel process were tested in the course of high-speed gas chromatographic separations of light hydrocarbons mixture (C1-C4). The impact of modifying the amount of porogen and/or catalyst on the monolith properties were studied. At the best precursor/catalyst/porogen ratio evaluated, a column efficiency of about 6500 theoretical plates per meter was reached with a very good resolution (4.3) for very light compounds (C1-C2). The test mixture was baseline separated on a 70cm column. To our knowledge for the first time a silica-based monolithic capillary column was able to separate light hydrocarbons from methane to n-butane at room temperature with a back pressure in the range of gas chromatography facilities (under 4.1bar). © 2015 Elsevier B.V.

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