References of "Jérôme, Christine"
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See detailIn situ bidentate to tetradentate ligand exchange reaction in cobalt-mediated radical polymerization
Kermagoret, Anthony ULg; Jérôme, Christine ULg; Detrembleur, Christophe ULg et al

in European Polymer Journal (2015), 62

Organometallic-mediated radical polymerization (OMRP) has seen a significant growth in the last years notably due to the development of new metal complexes, especially cobalt derivatives. Despite of this ... [more ▼]

Organometallic-mediated radical polymerization (OMRP) has seen a significant growth in the last years notably due to the development of new metal complexes, especially cobalt derivatives. Despite of this, none of the reported complexes offers optimal control for monomers with very different reactivity, which somewhat limits the synthesis of copolymers. In order to expand the scope of cobalt-mediated radical polymerization (CMRP), we investigated an in situ ligand exchange reaction for modulating the properties of the cobalt complex at the polymer chain-end and adjusting the C-Co bond strength involved in the control process. With the aim of improving the synthesis of poly(vinyl acetate)-b-poly(n-butyl acrylate) copolymers, bidentate acetylacetonate ligands, which impart high level of control to the polymerization of vinyl acetate (VAc), were replaced in situ at the PVAc-cobalt chain-end by tetradentate Salen type ligands that are more suited to acrylates. [less ▲]

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See detailOrganocatalytic synthesis of bio-based cyclic carbonates from CO2 and vegetable oils
Alves, Margot ULg; Grignard, Bruno ULg; Gennen, Sandro ULg et al

in RSC Advances (2015), 5

Bio-based cyclic carbonates were synthesized by coupling CO2 with epoxidized linseed oil using a catalytic platform composed of a bicomponent organocatalyst. A screening of the catalytic activity of a ... [more ▼]

Bio-based cyclic carbonates were synthesized by coupling CO2 with epoxidized linseed oil using a catalytic platform composed of a bicomponent organocatalyst. A screening of the catalytic activity of a series of organic salts and ionic liquids used in combination with (multi)phenolic or fluorinated hydrogen bond donors was realized before highlighting the synergistic effect between the organocatalyst and the most efficient cocatalysts. These kinetics studies, followed by IR spectroscopy under pressure, enabled to optimize the reaction conditions and to provide quantitative formation of the cyclocarbonated vegetable oil in short reaction time without using any organic solvent. [less ▲]

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See detailNanocomposite foams of polypropylene and carbon nanotubes: preparation, characterization, and evaluation of their performance as EMI absorbers
Tran, Minh-Phuong; Thomassin, Jean-Michel ULg; Alexandre, Michaël et al

in Macromolecular Chemistry and Physics (2015), 216(12), 1302-1312

Highly expanded nanocomposite foams of polypropylene and carbon nanotubes (PP/CNT) are formed using supercritical carbon dioxide (scCO 2 ) technology. The foaming parameters (temperature, pressure) are ... [more ▼]

Highly expanded nanocomposite foams of polypropylene and carbon nanotubes (PP/CNT) are formed using supercritical carbon dioxide (scCO 2 ) technology. The foaming parameters (temperature, pressure) are investigated to establish their infl uence on the morphology of the resulting foams and their impact on the electrical con- ductivity. As promising electromagnetic-interference (EMI) absorbers, the EMI shielding performance of the foams is determined, and a preliminary relationship is established between foam morphology and the EMI shielding perfor- mance. The best candidates are highly expanded foams with a volume expansion of >25, containing 0.1 vol% CNTs; they are able to absorb more than 90% of the incident radiation between 25 and 40 GHz. [less ▲]

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See detailPreparation and characterizations of EGDE crosslinked chitosan electrospun membranes
Aqil, Abdelhafid ULg; Tchemtchoua, Victor T.; Colige, Alain ULg et al

in Clinical Hemorheology and Microcirculation (2015), 60(1), 39-50

Composite Crosslinked nanofibrous membranes of chitosan, ethylene glycol diglycidyl ether (EGDE) and polyethy- 10 lene oxide was successfully prepared with bead free morphology via electrospinning ... [more ▼]

Composite Crosslinked nanofibrous membranes of chitosan, ethylene glycol diglycidyl ether (EGDE) and polyethy- 10 lene oxide was successfully prepared with bead free morphology via electrospinning technique followed by heat mediated 11 chemical crosslinking. Architectural stability of nanofiber mat in aqueous medium was achieved by chemical crosslinking of 12 only 1% EGDE, and tensile strength tests revealed that increasing EGDE content has considerably enhance the elastic modu- 13 lus of nanofibers. The structure, morphology and mechanical properties of nanofibers were characterized by Attenuated Total 14 Reflection-Fourier Transform Infrared spectroscopy (ATR–FTIR), scanning electron microscopy (SEM) and Instron machine, 15 respectively. Skin fibroblasts and endothelial cells showedgood attachment, proliferation and viability on crosslinked electrospun 16 membranes. The results indicate a good biocompatibility and non-toxic nature of the resulted membrane. [less ▲]

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See detailPoly(ethylene glycol) grafted polylactide based copolymers for the preparation of PLA-based nanocarriers and hybrid hydrogel
Riva, Raphaël ULg; Schmeits, Stéphanie; Croisier, Florence ULg et al

in Clinical Hemorheology and Microcirculation (2015), 60

In previous works, poly(D,L-lactide-co-?CL-poly(ethylene glycol) (poly(D,L-La-co-?PEG?CL) amphiphilic graft- 10 copolymers were successfully synthesized according to a copper azide-alkyne cycloaddition ... [more ▼]

In previous works, poly(D,L-lactide-co-?CL-poly(ethylene glycol) (poly(D,L-La-co-?PEG?CL) amphiphilic graft- 10 copolymers were successfully synthesized according to a copper azide-alkyne cycloaddition (CuAAC) strategy. This paper aims 11 at reporting on the behavior of this amphiphilic copolymer in water, which was not studied in the previous paper. Moreover, 12 the ability of the copolymer to stabilize a PLA nanoparticles aqueous suspension is presented. For this purpose, dynamic 13 light scattering (DLS) and transmission electron microscopy (TEM) are proposed to characterize the nanoparticles in solution. 14 Otherwise, the strategy developed for the synthesis of the amphiphilic copolymers was adapted and extended to the synthesis of 15 PLA-based degradable hydrogel, potentially applicable as drug-loaded degradable polymer implant. [less ▲]

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See detailSynthesis and tensioactive properties of PEO-b-polyphosphate copolymers
Vanslambrouck, Stéphanie ULg; Clément, Benoit; Riva, Raphaël ULg et al

in RSC Advances (2015), 5(35), 27330-37337

Poly(ethylene oxide) (PEO)-b-polyphosphate copolymers made of hydrophilic PEO and hydrophobic polyphosphates are amphiphilic copolymers prone to self-assemble in water into nanoparticles. In this work ... [more ▼]

Poly(ethylene oxide) (PEO)-b-polyphosphate copolymers made of hydrophilic PEO and hydrophobic polyphosphates are amphiphilic copolymers prone to self-assemble in water into nanoparticles. In this work, nanoparticles are obtained by the self-assembly of PEO-b-polyphosphate copolymers in water in the absence of any organic co-solvent whatever the length of the pendant alkyl chain (between 4 and 7 carbon atoms) of the polyphosphate block. Remarkably, this solvent-free process remains efficient even for the most hydrophobic polyphosphate blocks. The critical aggregation concentration (CAC) of the block copolymers was determined by pyrene probe fluorescence. Finally, the efficiency of these copolymer surfactants to decrease the air–water interface was measured by air-bubble tensiometry. [less ▲]

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See detailSmall Angle X-ray Scattering Insights into the Architecture-Dependent Emulsifying Properties of Amphiphilic Copolymers in Supercritical Carbon Dioxide
Alaimo, David ULg; Hermida Merino, Daniel; Grignard, Bruno ULg et al

in Journal of Physical Chemistry B (2015), 119

The supramolecular assembly of a series of copolymers combining a PEO-rich hydrophilic and fluorinated CO2-philic sequences is analysed by synchrotron small-angle xray scattering (SAXS) in supercritical ... [more ▼]

The supramolecular assembly of a series of copolymers combining a PEO-rich hydrophilic and fluorinated CO2-philic sequences is analysed by synchrotron small-angle xray scattering (SAXS) in supercritical CO2, as well as in water/CO2 emulsions. These copolymers were designed to have the same molecular weight and composition, and to differ only by their macromolecular architecture. The investigated copolymers have random, block, and palm-tree architectures. Besides, thermo-responsive copolymer is also analysed, having a hydrophilic sequence becoming water-insoluble around 41 °C, i.e. just above the critical point of CO2. At the length scale investigated by SAXS, only the random copolymer appears to self-assemble in pure CO2, in the form of a disordered microgel-like network. The random, block and thermo-responsive copolymers are all able to stabilize water/CO2 emulsions but not the copolymer with the palm-tree architecture, pointing at the importance of macromolecular architecture for the emulsifying properties. A modelling of the SAXS data shows that the block and the thermo-responsive copolymers form spherical micelle-like structures containing about 70 % water and 30 % polymer. [less ▲]

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See detailInfluence of the protein context on the polyglutamine length-dependent elongation of amyloid fibrils
Huynen, Céline ULg; Willet, Nicolas ULg; Duwez, Anne-Sophie ULg et al

in Biochimica et Biophysica Acta-Proteins and Proteomics (2014)

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See detailDirect route to well-defined poly(ionic liquid)s by controlled radical polymerization in water
Cordella, Daniela ULg; Kermagoret, Anthony ULg; Debuigne, Antoine ULg et al

in ACS Macro Letters (2014), 3

The precision synthesis of poly(ionic liquid)s (PILs) in water is achieved for the first time by the cobalt-mediated radical polymerization (CMRP) of N-vinyl-3-alkylimidazolium-type monomers following two ... [more ▼]

The precision synthesis of poly(ionic liquid)s (PILs) in water is achieved for the first time by the cobalt-mediated radical polymerization (CMRP) of N-vinyl-3-alkylimidazolium-type monomers following two distinct protocols. The first involves the CMRP of various 1-vinyl-3-alkylimidazolium bromides conducted in water in the presence of an alkyl–cobalt(III) complex acting as a monocomponent initiator and mediating agent. Excellent control over molar mass and dispersity is achieved at 30 °C. Polymerizations are complete in a few hours, and PIL chain-end fidelity is demonstrated up to high monomer conversions. The second route uses the commercially available bis(acetylacetonato)cobalt(II) (Co(acac)2) in conjunction with a simple hydroperoxide initiator (tert-butyl hydroperoxide) at 30, 40, and 50 °C in water, facilitating the scaling-up of the technology. Both routes prove robust and straightforward, opening new perspectives onto the tailored synthesis of PILs under mild experimental conditions in water. [less ▲]

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See detailNanocomposites based on MWCNT and polystyrene, styrene-acrylonitrile copolymer, or polymethylmethacrylate, obtained by miniemulsion polymerization
Donescu, Dan; Corobea, Mihai Cosmin; Petcu, Cristian et al

in Journal of Applied Polymer Science (2014), 131(23), 411481-10

Free radical miniemulsion polymerization of styrene (St), St/acrylonitrile 3 : 1 mixture or methylmethacrylate in the presence of multiwalled carbon nanotubes (MWCNT) was proven as a convenient way to ... [more ▼]

Free radical miniemulsion polymerization of styrene (St), St/acrylonitrile 3 : 1 mixture or methylmethacrylate in the presence of multiwalled carbon nanotubes (MWCNT) was proven as a convenient way to obtain homogenous hybrids with perspectives in associated applications like foams specialties materials. Miniemulsion polymerization was viable up to 2% wt. MWCNT to monomer, without agglomerations. The grafting on MWCNT during the polymerization occurs without the need for supplementary functionalization and the polymer grafted nanotubes showed stable dispersions in the polymer solvent. Monomer polarity affected the grafting ability during the polymerization process. The nanocomposites obtained after purification and drying were used in foaming process. MWCNT presence in the related nanocomposites decreased the pore sizes in foam-like materials (for all three different matrices). At 1 wt % MWCNT content, low density (< 0.3 g/cm3), low pore size (< 10 μm) and high cell density (>109 cell/cm3) were achieved. [less ▲]

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See detailPolysaccharide-coated PCL nanofibers for wound dressing applications
Croisier, Florence ULg; Atanasova, Ganka; Poumay, Yves et al

in Advanced Healthcare Materials (2014), 3(12), 2032-2039

Polysaccharide-based nanofibers with amultilayered structure are prepared by combining electrospinning (ESP) and layer-by-layer (LBL) deposition techniques. Charged nanofibers are firstly prepared by ... [more ▼]

Polysaccharide-based nanofibers with amultilayered structure are prepared by combining electrospinning (ESP) and layer-by-layer (LBL) deposition techniques. Charged nanofibers are firstly prepared by electrospinning poly(ε-caprolactone) (PCL) with a block-copolymer bearing carboxylic acid functions. After deprotonation of the acid groups, the layer-by-layer deposition of polyelectrolyte polysaccharides, notably chitosan and hyaluronic acid, is used to coat the electrospun fibers. A multilayered structure is achieved by alternating the deposition of the positively charged chitosan with the deposition of a negatively charged polyelectrolyte. The construction of this multi-layered structure is followed by Zeta potential measurements, and confirmed by observation of hollow nanofibers resulting from the dissolution of the PCL core in a selective solvent. These novel polysaccharide-coated PCL fiber mats remarkably combine the mechanical resistance typical of the core material (PCL) – particularly in the hydrated state –, with the surface properties of chitosan. The control of the nanofiber structure offered by the electrospinning technology, makes the developed process very promising to precisely design biomaterials for tissue engineering. Preliminary cell culture tests corroborate the potential use of such system in wound healing applications. [less ▲]

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See detailPoly( N-vinylcaprolactam): A thermoresponsive macromolecule with promising future in biomedical field
Liu, Ji; Debuigne, Antoine ULg; Detrembleur, Christophe ULg et al

in Advanced Healthcare Materials (2014), 3(12), 1941-1968

Poly( N -vinylcaprolactam) (PNVCL) is a thermoresponsive and biocompatible polymer that raises an increasing interest in the biomedical area, especially in drug delivery systems (DDS) that include ... [more ▼]

Poly( N -vinylcaprolactam) (PNVCL) is a thermoresponsive and biocompatible polymer that raises an increasing interest in the biomedical area, especially in drug delivery systems (DDS) that include micelles, hydrogels, and hybrid particles. The thermoresponsiveness of PNVCL, used alone or in combination with other stimuli- responsive polymers or particles (pH, magnetic fi eld, or chemicals), is often key in the loading and/or release process in these DDS. The renewed focus on this polymer, which is known for decades, is to a large extent due to recent progress in synthetic strategies. Especially, the advent of efficient controlled radical polymerization (CRP) methods for NVCL monomer gives now access to unprecedented well-defi ned NVCL-based copolymers with unique properties. This Review article addresses up-to-date synthetic aspects, biological features, and biomedical applications of the latest NVCL-containing systems. [less ▲]

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See detailInput of supercritical carbon dioxide to polymer synthesis: an overview
Boyère, Cédric; Jérôme, Christine ULg; Debuigne, Antoine ULg

in European Polymer Journal (2014), 61

The ongoing search for environmentally friendlier alternative to the organic solvents used in chemical processes has led to the development of technologies based on supercritical carbon dioxide (scCO2 ... [more ▼]

The ongoing search for environmentally friendlier alternative to the organic solvents used in chemical processes has led to the development of technologies based on supercritical carbon dioxide (scCO2), which is non-flammable, non-toxic and relatively inert fluid. Polymer chemistry does not escape this trend and last achievements in the field of polymer synthesis in scCO2 are reviewed here. Without claiming to be exhaustive, we go through and discuss the benefits of the main polymerization processes in scCO2 including homogeneous, precipitation, dispersion, suspension and emulsion systems. A particular attention is drawn to water/carbon dioxide emulsion polymerization and to the suited surface active agents. This review also underlines that heterogeneous polymerization based on CO2 is more than a strategy for reducing the ecological footprint of the polymer production but it allows structuring the polymer materials into particles or highly interconnected macroporous networks. [less ▲]

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See detailRole of the polyQ length and non-polyQ regions during the aggregation process into amyloid fibrils of model polyQ proteins
Huynen, Céline ULg; Willet, Nicolas ULg; Buell, Alexander K et al

Poster (2014, November 26)

Nine neurodegenerative disorders, referred to as polyglutamine diseases and including Huntington’s disease, are associated with the abnormal expansion of a polyglutamine tract inside nine unrelated ... [more ▼]

Nine neurodegenerative disorders, referred to as polyglutamine diseases and including Huntington’s disease, are associated with the abnormal expansion of a polyglutamine tract inside nine unrelated proteins. This polyQ expansion is thought to be the major determinant in the development of neurotoxicity, triggering protein aggregation into amyloid fibrils. A large body of evidence however suggests that non-polyQ regions modulate the aggregation process triggered by polyQ expansions. The interplay between the polyQ tract and non-polyQ regions is complex and still not fully understood. In order to better understand it, we previously designed and characterized model polyQ proteins made of the beta-lactamase BlaP with 23, 30, 55 and 79Q inserted at position 197 or 216. Our first results had indicated that our model is relevant to study polyQ aggregation since it recapitulates the aggregation properties of polyQ disease-associated proteins: there is a Q-threshold for the spontaneous formation of amyloid fibrils in solution, and above the threshold, the longer the polyQ, the faster the aggregation. Moreover, the structure of BlaP and the position of insertion of the polyQ tract influence their aggregation properties in solution. This work aims to better understand, at the molecular level, (i) the precise role of the polyQ length (23, 30, 55, 61, 67, 73 and 79Q), (ii) the conformation of the host protein (native or unfolded BlaP), (iii) the location of the polyQ tract within BlaP (197 or 216), (iv) the flexibility of the polyQ flanking sequences, and (v) the origin of constraints applied by BlaP to the inserted polyQ tract (at its N- or C-terminal end) on the structural, thermodynamic and aggregation properties of BlaP-polyQ chimeras, using a wide range of biophysical techniques (e.g., spectroscopy methods, quartz crystal microbalance, atomic force microscopy and dynamic light scattering). The effect on the aggregation properties will be determined on the spontaneous aggregation into amyloid fibrils in solution, and on the nucleation and on the elongation steps of amyloid fibril formation. For this purpose, new chimeras containing 61, 67 and 73Q at position 197, or 55Q inserted at position 197 in between two different protease’s cleavage sites, that are relatively flexible, will be moreover created. Our results first demonstrate that the spontaneous aggregation into amyloid fibrils in solution is correlated to the polyQ length with an exponential growth function, and that the elongation rate is linearly correlated to the polyQ length, independently of the protein context (i.e., conformation of BlaP, and/or location of the polyQ tract, and/or polyQ peptides inserted or not within BlaP). However, the location of the polyQ tract inside BlaP, and/or its conformational state, and/or the flexibility of polyQ flanking sequences, and/or the origin of constraints applied to the polyQ tract drastically influence the ability of a polyQ tract to trigger the nucleation and/or the elongation step of amyloid fibrils (variation in the Q-threshold and in the absolute rate of both steps). Altogether, our results suggest that non-polyQ regions constitute an additional potential therapeutic target, more specific than drugs targeting the polyQ sequence, to interfere with the nucleation and/or the elongation of amyloid fibrils, associated to neurotoxicity. A possible drug could be constituted by a ligand specific to non-polyQ regions of disease-associated proteins, which further increases the constraints applied to the polyQ expansion to prevent the disease onset and/or progression. [less ▲]

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See detailDouble thermoresponsive di- and triblock copolymers based on N-vinylcaprolactam and N-vinylpyrrolidone: synthesis and comparative study of solution behaviour
Kermagoret, Anthony ULg; Mathieu, Kevin ULg; Thomassin, Jean-Michel ULg et al

in Polymer Chemistry (2014), 5(22), 6534-6544

Poly(N-vinylcaprolactam) (PNVCL) and poly(N-vinylpyrrolidone) (PNVP) are water soluble polymers of interest especially in the biomedical field. Moreover, PNVCL is characterized by a lower critical ... [more ▼]

Poly(N-vinylcaprolactam) (PNVCL) and poly(N-vinylpyrrolidone) (PNVP) are water soluble polymers of interest especially in the biomedical field. Moreover, PNVCL is characterized by a lower critical solution temperature close to 36 °C in water, which makes it useful for the design of thermoresponsive systems. In this context, we used the cobalt-mediated radical polymerization (CMRP) and reaction coupling (CMRC) for synthesizing a series of well-defined NVCL and NVP-based copolymers, including statistical copolymers as well as double thermoresponsive diblocks and triblocks. Dynamic light scattering and turbidimetry analyses highlighted the crucial impact of the copolymer composition and architecture on the cloud point temperature (TCP) of each segment and also their influence on the multistep assembly behaviour of block copolymers. Addition of NaCl enabled us to adjust the inter-TCP range of the di- and triblock in which selective precipitation of one block and self-assembly of the copolymer were favoured. Overall, data presented here provide a basis for the synthesis of a broad range of NVCL/NVP based copolymer architectures with a tunable thermal response in water. [less ▲]

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See detailSmart cross-linked polymer micelles for drug delivery
Riva, Raphaël ULg; Vanslambrouck, Stéphanie ULg; Ergül, Zeynep ULg et al

Conference (2014, November 11)

Nowadays, polymer crosslinking is widely used in industry to improve or to impart new properties to existing polymer material. In the pharmaceutical field, polymer crosslinking is of great interest for ... [more ▼]

Nowadays, polymer crosslinking is widely used in industry to improve or to impart new properties to existing polymer material. In the pharmaceutical field, polymer crosslinking is of great interest for the elaboration of drug delivery devices, mostly hydrogels. Nevertheless, crosslinking is also very useful in nanovectorization of active principle. Indeed, each day, new drugs are synthesized and available on the market but in too many cases, the high hydrophobicity of some drugs makes them useless because of the absence of an appropriated administration method. The encapsulation of the drug into a nanocarrier, typically in the hydrophobic core of a polymer micelle, allows a significant increase of the drugs concentration in water in addition to the protection of the active principle against degradation. However, polymer micelles suffer of the main drawback to not be stable, leading to a premature release of the drug, when the concentration falls down the critical micellar concentration (CMC), which it is rapidly observed after intravenous injection. In order to get rid of the CMC, crosslinking of the micelle core is the most proposed strategy. Nevertheless, the crosslinking of the micelle core may have a non-negligible effect on the drug loading but mainly on the drug release due to the sequestration of the drug in the network. Over the last years, our lab investigated several strategies for the crosslinking of the micelle core made of amphiphilic and biocompatible block copolymers generally by UV radiation in order to fulfill the increasingly stringent requirements of biomedical applications. These strategies are very helpful to prepare injectable nanosized cross-linked particles loaded with an active particle. For some systems, the effect of the crosslinking rate on the drug loading and the drug release was evaluated using a model drug. As the crosslinking may interfere with the drug release after internalization of the carrier into the cell, a reversible crosslinking of the micelle core was proposed. Typically, the introduction of disulfide bond as inter-chain links allowed to delay the drug release by diffusion whereas into the cell, the reduction of the disulfide bridges into corresponding thiol led to the fast disassemble of the micelle and the specific release of the drug into cytoplasm. [less ▲]

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See detailGraphene functionalization using electrografting for energy storage application
Aqil, Abdelhafid ULg; Ouhib, Farid ULg; Aqil, Mohamed ULg et al

Conference (2014, November 04)

Many methods have been developed in the last few decades to obtain high-quality graphene thin sheets. They are based on very different physicochemical processes. Here we demonstrate a novel one step and ... [more ▼]

Many methods have been developed in the last few decades to obtain high-quality graphene thin sheets. They are based on very different physicochemical processes. Here we demonstrate a novel one step and simple electrografting acrylate monomer method to exfoliate highly oriented pyrolytic graphite (HOPG) into thin nanoplatelets and even down to the single graphene sheet level. Among the high research activity in the area of surface modification, electrografting is a very powerful method which has received comparatively little attention. This is surprising because this technique has many attractive features for modification of conducting or semi-conducting surfaces. The main interest of the electrografting process is to solve the recurrent problem of the organic/substrates interface weakness. The electrografting warranties a robust polymer/substrates interface and offers the possibility to tailor the functionality of the grafted polymer film opening the door to a wide range of demanding technological applications. The graphene sheets obtained through electrografting process give a stable suspension in dimethyl formamide (DMF), and they can self-precipitate on the surface of substrates after adding water as an antisolvent due to their strong surface hydrophobicity. Interestingly, the continuous films obtained exhibit ultratransparency (∼98% transmittance), and the lateral size of the exfoliated graphene sheets observed by AFM ~1nm. Raman and TEM characterizations corroborate that the graphene sheets exfoliated by our electrochemical method preserve the intrinsic structure of grapheme and give preferentially monolayered graphene sheets. The electrochemical behaviour of the acrylate monomer grafted graphene sheets was evaluated in lithium-half cells with no addition of conductive additive or binder. The PAN grafted graphene dispersed in DMF was coated on Cu foil and dried in a vacuum oven at 55°C for 12h. After 200 cycles, the reversible capacity was still kept at 300mAh/g at the current density of 50mA/g. These results indicate that the prepared high quality graphene sheets possess good electrochemical performances for lithium storage. This work provides an efficient approach to obtain high-quality, cost-effective, and scalable production of “graphene ink”, which may pave a way toward future applications in lithium-ion batteries. [less ▲]

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See detailRole of non-polyQ regions on the aggregation process by polyQ proteins into amyloid fibrils
Huynen, Céline ULg; Willet, Nicolas ULg; Buell, Alexander K et al

Poster (2014, October 18)

Nine neurodegenerative disorders, referred to as polyglutamine diseases and including Huntington’s disease, are associated with the abnormal expansion of a polyglutamine tract inside nine unrelated ... [more ▼]

Nine neurodegenerative disorders, referred to as polyglutamine diseases and including Huntington’s disease, are associated with the abnormal expansion of a polyglutamine tract inside nine unrelated proteins. This polyQ expansion is thought to be the major determinant in the development of neurotoxicity, triggering protein aggregation into amyloid fibrils. A large body of evidence however indicates that non-polyQ regions modulate the aggregation process triggered by polyQ expansions. The interplay between the polyQ tract and non-polyQ regions is complex and still not fully understood. In order to better understand it, we previously designed and characterized model polyQ proteins made of the beta-lactamase BlaP and a 23, 30, 55 or 79Q tract inserted in position 197 or 216. These chimeras recapitulate the aggregation properties of polyQ disease-associated proteins: there is a Q-threshold for the formation of amyloid fibrils, and above the threshold, the longer the polyQ, the faster the aggregation. Moreover, the structure of BlaP (native or unfolded) and the position of insertion of the polyQ tract (197 versus 216) influence their aggregation properties. In this work, (i) we discuss the role of the conformation of the host protein, BlaP, and of the location of the polyQ within BlaP on the different phases of amyloid fibril formation, the nucleation and elongation steps, using mainly quartz crystal microbalance (QCM), atomic force microscopy (AFM). Our results highlight a linear dependence of the polyQ length on the elongation rate whatever the insertion site and the conformation of BlaP. These two parameters however drastically influence the ability of a polyQ tract to trigger the nucleation and the elongation steps of amyloid fibril formation. (ii) Finally, we investigate the precise aggregation threshold and the modulating role of the N- and C-terminal polyQ flanking sequences in position 197 of BlaP by creating and characterizing new chimeras containing intermediate length polyQ tracts in position 197, or polyQ tracts inserted between two cleavage sites in position 197, respectively. We observe that the propensity to trigger the full process of amyloid fibril formation and its rate seems to be largely dependent on the polyQ length and on the polyQ flanking sequences. Altogether our results contribute to identify the important species and elements (polyQ or non-polyQ regions, monomers, oligomers or fibrils) during the aggregation process into amyloid fibrils to interfere with the latter associated with neurotoxicity. [less ▲]

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