References of "Duwez, Anne-Sophie"
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See detailCollapsing and reswelling kinetics of thermoresponsive polymers on surfaces: a matter of confinement and constraints
Willet, Nicolas ULg; Gabriel, Sabine ULg; Jérôme, Christine ULg et al

in Soft Matter (2014), 10

We report on the collapsing and reswelling ability of grafted poly(methyl vinyl ether) chains of different molecular architectures. In order to study the influence of constraints and confinement of the ... [more ▼]

We report on the collapsing and reswelling ability of grafted poly(methyl vinyl ether) chains of different molecular architectures. In order to study the influence of constraints and confinement of the chains, the polymer was grafted onto AFM tips, as a model of a curved nano-sized surface, and onto macroscopic silicon substrates for comparison purposes. AFM-based force spectroscopy experiments were performed to characterise at the nanoscale the temperature-dependent collapsing process and the reversibility to the swollen state on both substrates. The reversible character of the thermoresponsive transition and its kinetics were shown to greatly depend on the polymer architecture and the constraints encountered by the chains. [less ▲]

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See detailThe Dynamics of Complex Formation between Amylose Brushes on Gold and Fatty Acids by QCM‐D
Cao, Zheng; Tsoufis, Theodoros; Svaldo Lanero, Tiziana ULg et al

in Biomacromolecules (2013), 14

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See detailThe pulling force of a tiny synthetic molecular machine
Svaldo Lanero, Tiziana ULg; Duwez, Anne-Sophie ULg

in Europhysics News (2013), 44

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See detailSynthesis of poly(vinyl acetate)-b-poly(vinyl chloride) block copolymers by cobalt-mediated radical polymerization (CMRP)
Piette, Yasmine; Debuigne, Antoine ULg; Bodart, Vinent et al

in Polymer Chemistry (2013), 4(5), 1685-1693

The synthesis of poly(vinyl acetate)-b-poly(vinyl chloride) (PVAc-b-PVC) block copolymers by Cobalt-Mediated Radical Polymerization (CMRP) is investigated for the first time in this paper. A PVAc–Co(acac ... [more ▼]

The synthesis of poly(vinyl acetate)-b-poly(vinyl chloride) (PVAc-b-PVC) block copolymers by Cobalt-Mediated Radical Polymerization (CMRP) is investigated for the first time in this paper. A PVAc–Co(acac)2 macroinitiator is prepared by CMRP using the V-70/Co(acac)2 binary system or a preformed alkylcobalt(III) compound. Then, the block copolymerization occurs in the bulk at 40 °C by the addition of VC. The addition of water to the polymerization medium or the slow generation of alkyl radicals during the whole polymerization is beneficial to the process by consuming part of the excess of deactivator (Co(acac)2) that blocks the polymer chains into the dormant form. Dynamic light scattering (DLS) measurements and AFM analyses evidence that the PVAc-b-PVC forms core–shell micelles in a selective solvent of the PVAc block, i.e. methanol, evidencing the blocky structure of the copolymer. PVAc-b-P(VC-co-VAc) copolymers are also successfully prepared by initiating the radical copolymerization of VC and VAc at 40 °C from a PVAc–Co(acac)2 macroinitiator. [less ▲]

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See detailFunctional nanogels as platforms for imparting antibacterial, antibiofilm, and antiadhesion activities to stainless steel
Faure, Emilie ULg; Falentin, Céline ULg; Svaldo Lanero, Tiziana ULg et al

in Advanced Functional Materials (2012), 22(24), 5271-5282

In this work, long-term antibacterial, antiadhesion, and antibiofilm activities are afforded to industrial stainless steel surfaces following a green and bio-inspired strategy. Starting from catechol ... [more ▼]

In this work, long-term antibacterial, antiadhesion, and antibiofilm activities are afforded to industrial stainless steel surfaces following a green and bio-inspired strategy. Starting from catechol bearing synthetic polymers, the film cross-linking and the grafting of active (bio)molecules are possible under environmentally friendly conditions (in aqueous media and at room temperature). A bio-inspired polyelectrolyte, a polycation-bearing catechol, is used as the film-anchoring polymer while a poly(methacrylamide)-bearing quinone groups serves as the cross-linking agent in combination with a polymer bearing primary amine groups. The amine/quinone reaction is exploited to prepare stable solutions of nanogels in water at room temperature that can be easily deposited to stainless steel. This coating provides quinonefunctionalized surfaces that are then used to covalently anchor active (bio) molecules (antibiofi lm enzyme and antiadhesion polymer) through thiol/ quinone reactions. [less ▲]

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See detailSINGLE-MOLECULE AFM STUDY OF ADHESIVE POLYMERS PREPARED BY COBALT-MEDIATED RADICAL POLYMERIZATION AND NITRONE-MEDIATED RADICAL COUPLING
Willet, Nicolas ULg; Sluysmans, Damien ULg; Delvaux, Cédric ULg et al

Scientific conference (2012, September 10)

Well-defined poly(vinyl acetate) (PVAc) chains prepared by CMRP (cobalt-mediated radical polymerization) were coupled using an alkyne-functional nitrone via NMRC (nitrone-mediated radical coupling).1 In ... [more ▼]

Well-defined poly(vinyl acetate) (PVAc) chains prepared by CMRP (cobalt-mediated radical polymerization) were coupled using an alkyne-functional nitrone via NMRC (nitrone-mediated radical coupling).1 In all the cases, the coupling efficiencies were close to 90% or higher. The polymers mid-chain functionalized with an alkyne group were then reacted with azide-functionalized atomic force microscopy (AFM) tips via copper-catalyzed azide-alkyne cycloaddition (CuAAC). As a result, polymers having a double-branch architecture were linked to AFM tips via a short linker. The structure and the molecular parameters of the polymers were determined by NMR and GPC, whereas the ‘click’ step onto AFM tips was assessed by performing the same CuAAC reaction onto macroscopic surfaces and characterizing them by ATR FT-IR. The adhesive properties of these double-branched polymers were studied by AFM single-molecule force spectroscopy. By performing approach-retraction cycles in solution upon a glass surface, the interaction between single PVAc chains and the surface was investigated. The effect of the double-branch architecture on the adhesion forces was under focus. Setting a residence time of the tip on the surface before retraction was found to have a beneficial influence on the adhesion forces. Signs of multiple interactions acting in parallel were detected in the experimental force-distance traces. [less ▲]

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See detailUNFOLDING SYNTHETIC PEPTIDES BY AFM AT THE SINGLE-MOLECULE LEVEL
Willet, Nicolas ULg; Hinterdorfer, Peter; lecommandoux, Sébastien et al

Conference (2012, September)

The aim of this study is to investigate the mechanochemical behavior of homopolypeptides able to change their conformation is a stimuli-responsive way. The peptidic secondary structures were studied in ... [more ▼]

The aim of this study is to investigate the mechanochemical behavior of homopolypeptides able to change their conformation is a stimuli-responsive way. The peptidic secondary structures were studied in detail by atomic force microscopy (AFM) at the single-molecule level. Synthetic copolymers containing a polypeptide block were prepared by N-carboxyanhydride amino acid ring-opening polymerization. The polymer chains were grafted as a dilute brush onto gold surfaces and their mechanochemical behavior was then studied by AFM single-molecule force spectroscopy (SMFS). The investigated polypeptide blocks were based on poly(L-glutamic acid), which undergoes a transition from alpha-helix to random coil. This can be induced by external stimuli (pH, ionic strength, temperature) or simply by applying a force. We were able to study the mechanically driven unfolding of the peptide by stretching-release cycles of the biomacromolecule. Stretching the helical peptide resulted in original features in the force-distance traces. Plateaus that are specific for the helical conformation were detected, quantified and discussed. Pulling-relaxing SMFS experiments will eventually lead to a better understanding of the force-induced unfolding of an alpha-helix and the reversibility of the phenomenon. [less ▲]

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See detailUNFOLDING SYNTHETIC PEPTIDES BY AFM AT THE SINGLE-MOLECULE LEVEL
Willet, Nicolas ULg; Hinterdorfer, Peter; Lecommandoux, Sébastien et al

Poster (2012, September)

The aim of this study is to investigate the mechanochemical behavior of homopolypeptides able to change their conformation is a stimuli-responsive way. The peptidic secondary structures were studied in ... [more ▼]

The aim of this study is to investigate the mechanochemical behavior of homopolypeptides able to change their conformation is a stimuli-responsive way. The peptidic secondary structures were studied in detail by atomic force microscopy (AFM) at the single-molecule level. Synthetic copolymers containing a polypeptide block were prepared by N-carboxyanhydride amino acid ring-opening polymerization. The polymer chains were grafted as a dilute brush onto gold surfaces and their mechanochemical behavior was then studied by AFM single-molecule force spectroscopy (SMFS). The investigated polypeptide blocks were based on poly(L-glutamic acid), which undergoes a transition from alpha-helix to random coil. This can be induced by external stimuli (pH, ionic strength, temperature) or simply by applying a force. We were able to study the mechanically driven unfolding of the peptide by stretching-release cycles of the biomacromolecule. Stretching the helical peptide resulted in original features in the force-distance traces. Plateaus that are specific for the helical conformation were detected, quantified and discussed. Pulling-relaxing SMFS experiments will eventually lead to a better understanding of the force-induced unfolding of an alpha-helix and the reversibility of the phenomenon. [less ▲]

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See detailA green and bio-inspired process to afford durable anti-biofilm properties to stainless steel
Faure, Emilie; Vreuls, Christelle; Falentin-Daudré, Céline et al

in Biofouling (2012), 28(7), 719-728

A bio-inspired durable anti-biofilm coating was developed for industrial stainless steel (SS) surfaces. Two polymers inspired from the adhesive and cross-linking properties of mussels were designed and ... [more ▼]

A bio-inspired durable anti-biofilm coating was developed for industrial stainless steel (SS) surfaces. Two polymers inspired from the adhesive and cross-linking properties of mussels were designed and assembled from aqueous solutions onto SS surfaces to afford durable coatings. Trypsin, a commercially available broad spectrum serine protease, was grafted as the final active layer of the coating. Its proteolytic activity after long immersion periods was demonstrated against several substrata, viz. a synthetic molecule, N-a-benzoyl-DL-arginine-p-nitroanilide hydrochloride (BAPNA), a protein, FTC-casein, and Gram-positive biofilm forming bacterium Staphylococcus epidermidis. [less ▲]

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See detailMechanochemical Study of Conformational Transitions in a Single Synthetic Peptide Chain
Willet, Nicolas ULg; Hinterdorfer, Peter; Lecommandoux, Sébastien et al

Poster (2012, June 05)

The aim of this study is to investigate the mechanochemical behavior of homopolypeptides able to change their conformation is a stimuli-responsive way. The peptidic secondary structures were studied in ... [more ▼]

The aim of this study is to investigate the mechanochemical behavior of homopolypeptides able to change their conformation is a stimuli-responsive way. The peptidic secondary structures were studied in detail by atomic force microscopy (AFM) at the single-molecule level. Synthetic copolymers containing a polypeptide block were prepared by N-carboxyanhydride amino acid ring-opening polymerization. The polymer chains were grafted as a dilute brush onto gold surfaces via disulfide end-groups. Their mechanochemical behavior was then studied by AFM single-molecule force spectroscopy (SMFS). The investigated polypeptide blocks were based on poly(L-glutamic acid), which undergoes a transition from alpha-helix to random coil. This can be induced by external stimuli (pH, ionic strength, temperature) or simply by applying a force. We were able to study the mechanically driven unfolding of the peptide by stretching-release cycles of the biomacromolecule. Stretching the helical peptide resulted in original features in the force-distance traces. Plateaus that are specific for the helical conformation were detected, quantified and discussed. Pulling-relaxing SMFS experiments eventually led to a better understanding of the force induced unfolding of an alpha-helix and the reversibility of the phenomenon. [less ▲]

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See detailProbing recognition processes, forces and motions within single molecules
Willet, Nicolas ULg; Duwez, Anne-Sophie ULg

Scientific conference (2012, May 09)

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See detailAntibacterial polyelectrolyte micelles for coating stainless steel
Falentin, Céline ULg; Faure, Emilie ULg; Svaldo Lanero, Tiziana ULg et al

in Langmuir (2012), 28(18), 7233-7241

In this study, we report on the original synthesis and characterization of novel antimicrobial coatings for stainless steel by alternating the deposition of aqueous solutions of positively charged ... [more ▼]

In this study, we report on the original synthesis and characterization of novel antimicrobial coatings for stainless steel by alternating the deposition of aqueous solutions of positively charged polyelectrolytes micelles doped with silver based nanoparticles with a polyanion. The micelles are formed by electrostatic interaction between two oppositely charged polymers, a polycation bearing 3,4-dihydroxyphenylalanine units (DOPA, a major component of natural adhesives) and a polyanion (poly(styrene sulfonate), PSS) without using any block copolymer. DOPA units are exploited for their well-known ability to anchor to stainless steel and to form and stabilize biocidal silver nanoparticles (Ag0). The chlorine counter-anion of the polycation forms and stabilizes biocidal silver chloride nanoparticles (AgCl). We demonstrate that two layers of micelles (alternated by PSS) doped by silver particles are enough to impart to the surface a strong antibacterial activity against Gram-negative E. coli. Moreover, micelles that are reservoirs of biocidal Ag+ can be easily reactivated after depletion. This novel water-based approach is convenient, simple and attractive for industrial applications. [less ▲]

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See detailMolecular biomimetics applied to medical devices
Van de Weerdt, Cécile ULg; Archembeau, Catherine; Vreuls, Christelle ULg et al

Poster (2012, May 05)

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See detailBiomolecule-based antibacterial coating on a stainless steel surface: multilayer film build-up optimization and stability study.
Vreuls, Christelle ULg; Zocchi, Germaine ULg; Vandegaart, Hélène ULg et al

in Biofouling (2012), 28(4), 395-404

The goal of this paper was to establish the durability profile of antibacterial multilayer thin films under storage and usage conditions. Thin films were built on stainless steel (SS) by means of a layer ... [more ▼]

The goal of this paper was to establish the durability profile of antibacterial multilayer thin films under storage and usage conditions. Thin films were built on stainless steel (SS) by means of a layer-by-layer process alternating a negatively charged polyelectrolyte, polyacrylic acid, with a cationic antibacterial peptide, nisin. SS coupons coated with the antibacterial film were challenged under environmental and usage conditions likely to be encountered in real-world applications. The change in antibacterial activity elicited by the challenge was used as an indicator of multilayer film resistance. Antibacterial SS samples could be stored for several weeks at 4°C in ambient air and antibacterial films were resistant to dipping and mild wiping in water and neutral detergent. The multilayer coating showed some weaknesses, however, that need to be addressed. [less ▲]

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See detailMolecular biomimetics applied to medical devices
Van de Weerdt, Cécile ULg; Vreuls, Christelle ULg; Genin, Alexis ULg et al

Poster (2012, April 18)

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See detailClay and DOPA containing polyelectrolyte multilayer film for imparting anticorrosion properties to galvanized steel
Faure, Emilie ULg; Halusiak, Emilie; Farina, Fabrice et al

in Langmuir (2012), 28(5), 2971-2978

A facile and green approach is developed to impart remarkable protection against corrosion to galvanized steel. A protecting multilayer film is formed by alternating the deposition of a polycation bearing ... [more ▼]

A facile and green approach is developed to impart remarkable protection against corrosion to galvanized steel. A protecting multilayer film is formed by alternating the deposition of a polycation bearing catechol groups, used as corrosion inhibitors, with clay that induces barrier properties. This coating does not affect the esthetical aspect of the surface and does not release any toxic molecules in the environment. [less ▲]

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See detailMechanical testing of electrospun PCL fibers
Croisier, Florence ULg; Duwez, Anne-Sophie ULg; Jérôme, Christine ULg et al

in Acta Biomaterialia (2012), 8(1), 218-224

Poly(ε-caprolactone) (PCL) fibers ranging from 250 to 700 nm in diameter were produced by electrospinning a polymer tetrahydrofuran/N,N-dimethylformamide solution. The mechanical properties of the fibrous ... [more ▼]

Poly(ε-caprolactone) (PCL) fibers ranging from 250 to 700 nm in diameter were produced by electrospinning a polymer tetrahydrofuran/N,N-dimethylformamide solution. The mechanical properties of the fibrous scaffolds and individual fibers were measured by different methods. The Young’s moduli of the scaffolds were determined using macro-tensile testing equipment, whereas single fibers were mechanically tested using a nanoscale three-point bending method, based on atomic force microscopy and force spectroscopy analyses. The modulus obtained by tensile-testing eight different fiber scaffolds was 3.8 ± 0.8 MPa. Assuming that PCL fibers can be described by the bending model of isotropic materials, a Young’s modulus of 3.7 ± 0.7 GPa was determined for single fibers. The difference of three orders of magnitude observed in the moduli of fiber scaffolds vs. single fibers can be explained by the lacunar and random structure of the scaffolds. [less ▲]

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