References of "Jérôme, Christine"
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See detailEffect of head-to-head addition in vinyl acetate controlled radical polymerization: why is Co(acac)2-mediated polymerization so much better?
Morin, Aurélie N.; Detrembleur, Christophe ULg; Jérôme, Christine ULg et al

in Macromolecules (2013), 46(11), 4303-4312

The controlled polymerization of vinyl acetate has been recently achieved by several techniques, but PVAc with targeted Mn and low dispersity up to very high monomer conversions and high degrees of ... [more ▼]

The controlled polymerization of vinyl acetate has been recently achieved by several techniques, but PVAc with targeted Mn and low dispersity up to very high monomer conversions and high degrees of polymerization was only obtained with Co(acac)2 as controlling agent in the so-called CMRP, a type of organometallic mediated radical polymerization (OMRP). Other techniques (including ATRP, ITP, TERP, and RAFT/MADIX) have shown a more or less pronounced slowdown in the polymerization kinetics, which was attributed to the higher strength of the C−X bond between the radical PVAc chain and the trapping agent (X) in the dormant species and to a consequent slower reactivation after a less frequent head-to-head monomer addition. The reason for the CMRP exception is clarified by the present contribution. First, a detailed investigation by 1H, 13C and multiplicity-edited HSQC and DEPT-135 NMR of the PVAc obtained by CMRP, in comparison with a regular polymer made by free radical polymerization under the same conditions, has revealed that Co(acac)2 does not significantly alter the fraction of head-to-head sequences in the polymer backbone and that there is no accumulation of Co(acac)2-capped chains with a head-to-head ω end. Hence, both dormant chains (following the head-to-head and the head-to-tail monomer additions) must be reactivated at similar rates. A DFT study shows that this is possible because the dormant chains are stabilized not only by the C−Co σ bond but also by formation of a chelate ring through coordination of the ω monomer carbonyl group. The head-to-head dormant chain contains an inherently stronger C−Co bond but forms a weaker 6-membered chelate ring, whereas the weaker C−Co bond in the head-to-tail dormant chain is compensated by a stronger 5-membered chelate ring. Combination of the two effects leads to similar activation enthalpies, as verified by DFT calculations using a variety of local, gradient-corrected, hybrid and “ad hoc” functionals (BPW91, B3PW91, BPW91*, M06 and M06L). While the BDE(C−X) of model H-VAc−X molecules [X = Cl, I, MeTe, EtOC(S)S and Co(acac)2] are functional dependent, the BDE difference between head-to-head and head-to-tail dormant chain models is almost functional insensitive, with values of 5−9 kcal/mol for the ATRP, ITP and TERP models, 3−6 for the RAFT/MADIX model, and around zero for CMRP. [less ▲]

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See detailThe influence of foam morphology of multi-walled carbon nanotubes/poly(methyl methacrylate) nanocomposites on electrical conductivity
Tran, Minh Phuong ULg; Detrembleur, Christophe ULg; Alexandre, Michaël ULg et al

in Polymer (2013), 54(13), 3261-3270

Polymer/multi-walled carbon nanotubes (PMMA/MWNTs) nanocomposites foams are widely investigated during the last decade thanks to their potential applications as electromagnetic interferences shielding ... [more ▼]

Polymer/multi-walled carbon nanotubes (PMMA/MWNTs) nanocomposites foams are widely investigated during the last decade thanks to their potential applications as electromagnetic interferences shielding (EMI) materials. Electrical conductivity of the nanocomposite is a key parameter for these applications. In the frame of this work, we aim at establishing relationships between the foams morphology and their electrical conductivity. We therefore first design nanocomposite foams of various morphologies using supercritical carbon dioxide (scCO2) as physical foaming agent. The nanocomposites based on poly(methyl methacrylate) (PMMA) and different carbon nanotubes loadings are prepared by melt-mixing and foamed by scCO2 in various conditions of pressure, temperature and soaking time. The influence of these foaming conditions on the morphology of the foams (volume expansion, pore size, cell density, cell-wall thickness) is discussed. After measuring the electrical conductivity of the foams, we establish structure/properties relationships that are essential for further optimizations of the materials for the targeted application. [less ▲]

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See detailNovel phenolic glycolipids: antioxidant activity and effect on membrane models
Sainvitu, Pauline ULg; Nasir, Mehmet Nail ULg; Draguet, Florian et al

Poster (2013, May 30)

Aromatic glycolipids are of both medical as well as pharmaceutical interest. Antimicrobial, antiviraland antiinflammatory activities have been reported (Otto, 2000, Journal of Molecular Catalysis B ... [more ▼]

Aromatic glycolipids are of both medical as well as pharmaceutical interest. Antimicrobial, antiviraland antiinflammatory activities have been reported (Otto, 2000, Journal of Molecular Catalysis B: Enzymatic). Moreover, they are expected to have interesting antioxidant properties when they contain phenolic groups. The alkyl chain should enhance their ability to penetrate into the cellular membrane (Nicolosi, 2002, Journal of Molecular Catalysis B: Enzymatic). The presence of a sugar unit could also be useful to target specific cells. In this study, novel aromatic glycolipids were synthesized as useful models for studying the structure–activity relationship, in particular as regards to their aromatic group.Theireffect on cell viability when an oxidative stress is induced was tested. In parallel, their interaction with cell models (liposomes) was studied through membrane fusion and permeability experiments. [less ▲]

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See detailMacroporous polyhipes from CO2-in-water emulsion templates stabilized by new sugar-based surfactants
Boyère, Cédric ULg; Favrelle, Audrey; Léonard, Alexandre F. et al

Poster (2013, May 16)

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See detailSurface activity of a fluorinated carbohydrate ester in water/carbon dioxide emulsions
Favrelle, Audrey; Boyère, Cédric ULg; Tran, Kien My et al

in Journal of Colloid & Interface Science (2013), 398

The water/carbon dioxide (W/CO2) interfacial activity and emulsifying capacity of hydrocarbon and fluorinated carbohydrate esters are investigated of the first time and compared to the performance of ... [more ▼]

The water/carbon dioxide (W/CO2) interfacial activity and emulsifying capacity of hydrocarbon and fluorinated carbohydrate esters are investigated of the first time and compared to the performance of sodium-bis(2-ethylhexyl)sulfosuccinate (AOT). The reduction of the W/CO2 interfacial tension was measured using a pendant drop tensiometer equipped with a cell view pressurized with CO2 at 80 bar and 45 °C. It was found that the interface stabilization improved in the order AOT < 6-O-myristoyl mannose < 6-O-(2H,2H,3H,3H-perfluoroundecanoyl)-D-mannose. In the latter case, a drastic reduction of the W/CO2 interfacial tension was observed (85% reduction, interfacial tension at the equilibrium = 3.6 mN/m), which emphasizes the advantage of using a fluorinated CO2-philic tail and the potential of sugars as hydrophilic head. The formulation of stable W/CO2 emulsions was also achieved using the fluorinated mannose derivative. This study paves the way to the design of a novel class of competitive surface active agents for W/CO2 emulsions. [less ▲]

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See detailBiophysical characterization of the interaction of novel aromatic glycolipid surfactants with membrane models.
Sainvitu, Pauline ULg; Nasir, Mehmet Nail ULg; Draguet, Florian et al

Poster (2013, May 15)

Aromatic glycolipids are of both medical and pharmaceutical interest. Antimicrobial, antiviral and anti-inflammatory activities have been reported (Otto, 2000, Journal of Molecular Catalysis B: Enzymatic ... [more ▼]

Aromatic glycolipids are of both medical and pharmaceutical interest. Antimicrobial, antiviral and anti-inflammatory activities have been reported (Otto, 2000, Journal of Molecular Catalysis B: Enzymatic). Moreover, they are expected to have interesting antioxidant properties when they contain phenolic groups. The alkyl chain should enhance their ability to penetrate into the cellular membrane (Nicolosi, 2002, Journal of Molecular Catalysis B: Enzymatic). The presence of a sugar unit could also be useful to target specific cells. In this study, novel aromatic glycolipids were synthesized as useful models for studying the structure–activity relationship, in particular as a function of their aromatic group. Their interaction with membranes was studied with monolayer models and was predicted by a computational approach. The relationships between these data and their cytotoxicity and antioxidant properties evaluated on cell cultures are discussed. [less ▲]

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See detailBiophysical characterization of the interaction of novel aromatic glycolipid surfactants with membrane models.
Sainvitu, Pauline ULg; Nasir, Mehmet Nail ULg; Nott, Katherine ULg et al

in World Academy of Science, Engineering and Technology (2013, May), 77

Aromatic glycolipids are of both medical and pharmaceutical interest. Antimicrobial, antiviral and anti-inflammatory activities have been reported (Otto, 2000, Journal of Molecular Catalysis B: Enzymatic ... [more ▼]

Aromatic glycolipids are of both medical and pharmaceutical interest. Antimicrobial, antiviral and anti-inflammatory activities have been reported (Otto, 2000, Journal of Molecular Catalysis B: Enzymatic). Moreover, they are expected to have interesting antioxidant properties when they contain phenolic groups. The alkyl chain should enhance their ability to penetrate into the cellular membrane (Nicolosi, 2002, Journal of Molecular Catalysis B: Enzymatic). The presence of a sugar unit could also be useful to target specific cells. In this study, novel aromatic glycolipids were synthesized as useful models for studying the structure–activity relationship, in particular as a function of their aromatic group. Their interaction with membranes was studied with monolayer models and was predicted by a computational approach. The relationships between these data and their cytotoxicity and antioxidant properties evaluated on cell cultures are discussed. [less ▲]

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See detailBiophysical characterization of the interaction of novel aromatic glycolipid surfactants with membrane models.
Sainvitu, Pauline ULg; Nasir, Mehmet Nail ULg; Nott, Katherine ULg et al

in World Academy of Science, Engineering and Technology (2013, May), 77

Aromatic glycolipids are of both medical and pharmaceutical interest. Antimicrobial, antiviral and anti-inflammatory activities have been reported (Otto, 2000, Journal of Molecular Catalysis B: Enzymatic ... [more ▼]

Aromatic glycolipids are of both medical and pharmaceutical interest. Antimicrobial, antiviral and anti-inflammatory activities have been reported (Otto, 2000, Journal of Molecular Catalysis B: Enzymatic). Moreover, they are expected to have interesting antioxidant properties when they contain phenolic groups. The alkyl chain should enhance their ability to penetrate into the cellular membrane (Nicolosi, 2002, Journal of Molecular Catalysis B: Enzymatic). The presence of a sugar unit could also be useful to target specific cells. In this study, novel aromatic glycolipids were synthesized as useful models for studying the structure–activity relationship, in particular as a function of their aromatic group. Their interaction with membranes was studied with monolayer models and was predicted by a computational approach. The relationships between these data and their cytotoxicity and antioxidant properties evaluated on cell cultures are discussed. [less ▲]

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See detailIntraocular lenses with functionalized surfaces by biomolecules in relation with lens epithelial cell adhesion
Huang, Yi-Shiang ULg; Alexandre, Michaël ULg; Bozukova, Dimitriya et al

Poster (2013, April 25)

A cataract is pathology opacity of the lens or capsule of the eye, causing impairment of vision or even blindness. Surgery, with lens extraction and intraocular lens implantation, is still the only ... [more ▼]

A cataract is pathology opacity of the lens or capsule of the eye, causing impairment of vision or even blindness. Surgery, with lens extraction and intraocular lens implantation, is still the only currently available treatment. The most common complication after implantation of intraocular lenses (IOLs) is the posterior capsular opacification (PCO) or secondary cataract. This is the result of lens epithelial cells (LECs) proliferation and their transition to mesenchymal cells. In 1997, a Sandwich theory was proposed to elucidate the developmental process of PCO. [1] According to this model, an IOL with higher affinity to LECs will induce a less PCO. In our research, the pHEMA (Poly(2-hydroxyethyl methacrylate)) based acrylic hydrophilic polymer is subjected to the surface modification by conjugating with the bioactive peptides. The RGD sequence, known for its excellent biocompatibility, is designed to stimulate the biointegration between the LECs and the polymer implant. [2]. From our research, The RGD peptide immobilized onto pHEMA surfaces significantly facilitates the adhesion of the porcine LEC. The peptide immobilized surface retains its biological function even after 10 times of autoclave. On the other hand, the immobilized peptide does not alter the hydrophobicity of the surface, the light transmission, as well as the cytotoxicity of the material. This functionalized biomaterial would possibly prevent the formation of PCO. [1] J Cataract Refract Surg. 1997 Dec;23(10):1539-42 [2] Trends Biotechnol. 2008 Jul;26(7):382-92 [less ▲]

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See detailUse of supercritical carbon dioxide to elaborate drug-loaded polymeric implants
Champeau, Mathilde; Thomassin, Jean-Michel ULg; Jérôme, Christine ULg et al

Poster (2013, April 25)

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See detailOne-pot controlled synthesis of double thermoresponsive N-vinylcaprolactam-based copolymers with tunable LCSTs
Kermagoret, Anthony ULg; Fustin, Charles-André; Bourguignon, Maxime et al

in Polymer Chemistry (2013), 4(8), 2575-2583

N-Vinylcaprolactam (NVCL) was copolymerized statistically for the first time in a controlled manner with hydrophilic N-vinylamide or hydrophobic vinylester monomers in order to precisely tune up and down ... [more ▼]

N-Vinylcaprolactam (NVCL) was copolymerized statistically for the first time in a controlled manner with hydrophilic N-vinylamide or hydrophobic vinylester monomers in order to precisely tune up and down the lower critical solution temperature (LCST) of the resulting copolymers. The incorporation of these segments in complex architectures was also considered. Several narrowly distributed NVCL-based copolymers were prepared by cobalt-mediated radical polymerization (CMRP) using the bis-(acetylacetonato)cobalt(II) complex as a controlling agent and N-methyl-N-vinylacetamide (NMVA), N-vinylacetamide (NVA), vinyl acetate (VAc) or vinyl pivalate (VPi) as comonomers. PNVCL-containing block copolymers having two discrete LCSTs were also synthesized following a one-pot strategy based on the sequential CMRP of NVCL followed by the copolymerization of NMVA with the residual NVCL. Upon gradual heating of aqueous solutions of such double thermoresponsive copolymers, we noticed a transition from free chains to micelles before full dehydration and collapse of the block copolymers. These advances represent a significant step towards the development of a platform based on thermoresponsive PNVCL copolymers with a single phase separation or multistep assembly behaviors. [less ▲]

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See detailNanoparticles in biomedical imaging
Liu, Ji ULg; Jérôme, Christine ULg; Duguet, Etienne

Scientific conference (2013, April 19)

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See detailIn situ nitroxide-mediated polymerization of styrene promoted by the N-tert-butyl-alpha-isopropylnitrone/BPO pair: ESR investigations
Detrembleur, Christophe ULg; Clément, Jean-Louis; Sciannaméa, Valérie et al

in Journal of Polymer Science. Part A, Polymer Chemistry (2013), 51(8), 1786-1795

The styrene polymerization initiated by benzoyl peroxide (BPO) in the presence of N-tert-butyl--isopropylnitrone as nitroxide precursor is well-controlled provided that a prereaction between the nitrone ... [more ▼]

The styrene polymerization initiated by benzoyl peroxide (BPO) in the presence of N-tert-butyl--isopropylnitrone as nitroxide precursor is well-controlled provided that a prereaction between the nitrone and BPO is carried out in suitable conditions prior to polymerization at a higher temperature. Electron spin resonance (ESR) spectroscopy was implemented to probe the nitroxides formed during both steps, that is, the prereaction and polymerization, and to get crucial information regarding the structure of the nitroxides responsible for the polymerization control. ESR studies combined with first principles calculations have evidenced that nitroxides observed during the prereaction in the presence of styrene and during the polymerization steps consist of a mixture of two macronitroxides. One is formed by the addition of a growing polystyrene chain to the nitrone as would be expected. However, the second one results from the addition of a polystyrene chain to tert-butyl nitroso that is in situ formed presumably by decomposition of the first macronitroxide type. [less ▲]

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See detailDual anticancer drug/superparamagnetic iron oxide-loaded PLGA-based nanoparticles for cancer therapy and magnetic resonance imaging
Schleich, N.; Sibret, Pierre ULg; Danhier, P. et al

in International Journal of Pharmaceutics (2013), 447(1-2), 94-101

We developed dual paclitaxel (PTX)/superparamagnetic iron oxide (SPIO)-loaded PLGA-based nanoparticles for a theranostic purpose. Nanoparticles presented a spherical morphology and a size of 240 nm. The ... [more ▼]

We developed dual paclitaxel (PTX)/superparamagnetic iron oxide (SPIO)-loaded PLGA-based nanoparticles for a theranostic purpose. Nanoparticles presented a spherical morphology and a size of 240 nm. The PTX and iron loading were 1.84 ± 0.4 and 10.4 ± 1.93 mg/100 mg respectively. Relaxometry studies and phantom MRI demonstrated their efficacy as T2 contrast agent. Significant cellular uptake by CT26 cells of nanoparticles was shown by Prussian blue staining and fluorescent microscopy. While SPIO did not show any toxicity in CT-26 cells, PTX-loaded nanoparticles had a cytotoxic activity. PTX-loaded nanoparticle (5 mg/kg) with or without co-encapulated SPIO induced in vivo a regrowth delay of CT26 tumors. Together these multifunctional nanoparticles may be considered as future nanomedicine for simultaneous molecular imaging, drug delivery and real-time monitoring of therapeutic response. [less ▲]

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