Evaluation of constitutive models in predicting ratcheting responses of a structure under thermo-mechanical loadings

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Surfaces for heart cells:Establishing the optimum plasma surface engineering methodology on polystyrene for cardiac cell engineering

International audiencePlasma surface modification is a popular method for improving cellculture on surfaces, and polystyrene (PS) is literature’s materialof choice. This study identifies the optimum plasma treatment forpromoting normal cardiac cell behaviour during culture. PS slideswere plasma-treated with O2, N2, O2 + N2 and Ar + N2 for 20 and 30min in a reactive ion etcher (RIE). SEM reveals that O2 and O2 + N2plasmas create dual scale roughness, N2 plasma creates oval-shapedstructures, while Ar + N2 exhibits no topography. Evaluation by XPSreveals an increase in the atomic percentage of oxygen for alltreatments. Contact angle measurements agree as all treatments leadto hydrophilisation, with N2 samples exhibiting long-term stability. Two sources of cells were used to identify the optimum plasma treatment for cardiac cell culture on PS. H9c2 cells exhibit optimal ehaviour with N2 and N2 + Ar regarding viability, morphology, and focal adhesion contact. The same was observed for primary cardiomyocytes on N2 samples. For purified cardiomyocytes, immunofluorescence revealed well-organised sarcomeric structure on N2 samples, exhibiting clear improvement compared to control. SEM validated these findings, as cardiomyocytes on N2-treated PS exhibited physiological, elongated shape. These findings provide solid evidence that the optimum treatment for PS is the use of N2 plasma

Gold/Polyoxometalate Core/Shell Nanoparticles for Combined Chemotherapy–Photothermal Cancer Therapy

International audienceWe designed monodisperse and perfectly shaped core/shell AuNP@Mo4Zol2Mn nanohybrids consisting of gold nanoparticles (AuNPs) functionalized by an antitumoral polyoxometalate (POM) incorporating the biologically active zoledronate ligand. After incubation, the nanoparticles were readily confined in the endosomal compartments of PC3 human prostate adenocarcinoma cells. Under photothermal treatment, the metabolic activity drastically decreased at concentrations where the nanohybrids exhibited no anticancer activity in the dark, and almost all cancer cells were killed at concentrations at which zoledronate alone was totally inactive. This study evidences for the first time that AuNPs capped by POMs can represent excellent candidates for combined chemotherapy and photothermal cancer therapy

Bimetallic Phosphide (Ni,Cu) 2 P Nanoparticles by Inward Phosphorus Migration and Outward Copper Migration

International audienceBimetallic phosphide nanoparticles are drawing a great interest as a family of nanomaterials. Controlling their fine features such as surface composition, core crystal structure and overall composition is a key to further application. Copper and nickel are particularly interesting first-raw metals for their abundance and relevance in several branches of catalysis. In order to synthesize crystalline bimetallic phosphide Ni-CuP nanoparticles, core-shell copper-nickel nanoparticles were reacted with white phosphorus (P 4). Surprisingly, hollow monocrystalline (Ni,Cu) 2 P nanoparticles were formed alongside Cu nanoparticles and crystallized in a phase isostructural to Ni 2 P. Using a combination of local and ensemble analytic techniques, we showed that this unique structure is the result of several competing processes: phosphorus migration, interaction of stabilizing ligands with copper as well as metal phosphide phase crystallization. This study provides important mechanistic insights to rationalize bimetallic phosphide nanoparticles syntheses. Beyond metal phosphides, this well-characterized case study about competing diffusion and crystallization processes is of major relevance for the advancement of materials sciences at the nanoscale

Cyto- and bio-compatibility assessment of plasma-treated polyvinylidene fluoride scaffolds for cardiac tissue engineering

International audienceAs part of applications dealing with cardiovascular tissue engineering, drop-cast polyvinylidene fluoride (PVDF) scaffolds have been treated by cold plasma to enhance their adherence to cardiac cells. The scaffolds were treated in a dielectric barrier device where cold plasma was generated in a gaseous environment combining a carrier gas (helium or argon) with/without a reactive gas (molecular nitrogen). We show that an Ar-N2 plasma treatment of 10 min results in significant hydrophilization of the scaffolds, with contact angles as low as 52.4° instead of 132.2° for native PVDF scaffolds. Correlation between optical emission spectroscopy and X-ray photoelectron spectroscopy shows that OH radicals from the plasma phase can functionalize the surface scaffolds, resulting in improved wettability. For all plasma-treated PVDF scaffolds, the adhesion and maturation of primary cardiomyocytes is increased, showing a well-organized sarcomeric structure (α-actinin immunostaining). The efficacy of plasma treatment was also supported by real-time PCR analysis to demonstrate an increased expression of the genes related to adhesion and cardiomyocyte function. Finally, the biocompatibility of the PVDF scaffolds was studied in a cardiac environment, after implantation of acellular scaffolds on the surface of the heart of healthy mice. Seven and 28 days after implantation, no exuberant fibrosis and no multinucleated giant cells were visible in the grafted area, hence demonstrating the absence of foreign body reaction and the biocompatibility of these scaffolds

Cyto- and bio-compatibility assessment of plasma-treated polyvinylidene fluoride scaffolds for cardiac tissue engineering

International audienceAs part of applications dealing with cardiovascular tissue engineering, drop-cast polyvinylidene fluoride (PVDF) scaffolds have been treated by cold plasma to enhance their adherence to cardiac cells. The scaffolds were treated in a dielectric barrier device where cold plasma was generated in a gaseous environment combining a carrier gas (helium or argon) with/without a reactive gas (molecular nitrogen). We show that an Ar-N2 plasma treatment of 10 min results in significant hydrophilization of the scaffolds, with contact angles as low as 52.4° instead of 132.2° for native PVDF scaffolds. Correlation between optical emission spectroscopy and X-ray photoelectron spectroscopy shows that OH radicals from the plasma phase can functionalize the surface scaffolds, resulting in improved wettability. For all plasma-treated PVDF scaffolds, the adhesion and maturation of primary cardiomyocytes is increased, showing a well-organized sarcomeric structure (α-actinin immunostaining). The efficacy of plasma treatment was also supported by real-time PCR analysis to demonstrate an increased expression of the genes related to adhesion and cardiomyocyte function. Finally, the biocompatibility of the PVDF scaffolds was studied in a cardiac environment, after implantation of acellular scaffolds on the surface of the heart of healthy mice. Seven and 28 days after implantation, no exuberant fibrosis and no multinucleated giant cells were visible in the grafted area, hence demonstrating the absence of foreign body reaction and the biocompatibility of these scaffolds

Cyto- and bio-compatibility assessment of plasma-treated polyvinylidene fluoride scaffolds for cardiac tissue engineering

International audienceAs part of applications dealing with cardiovascular tissue engineering, drop-cast polyvinylidene fluoride (PVDF) scaffolds have been treated by cold plasma to enhance their adherence to cardiac cells. The scaffolds were treated in a dielectric barrier device where cold plasma was generated in a gaseous environment combining a carrier gas (helium or argon) with/without a reactive gas (molecular nitrogen). We show that an Ar-N2 plasma treatment of 10 min results in significant hydrophilization of the scaffolds, with contact angles as low as 52.4° instead of 132.2° for native PVDF scaffolds. Correlation between optical emission spectroscopy and X-ray photoelectron spectroscopy shows that OH radicals from the plasma phase can functionalize the surface scaffolds, resulting in improved wettability. For all plasma-treated PVDF scaffolds, the adhesion and maturation of primary cardiomyocytes is increased, showing a well-organized sarcomeric structure (α-actinin immunostaining). The efficacy of plasma treatment was also supported by real-time PCR analysis to demonstrate an increased expression of the genes related to adhesion and cardiomyocyte function. Finally, the biocompatibility of the PVDF scaffolds was studied in a cardiac environment, after implantation of acellular scaffolds on the surface of the heart of healthy mice. Seven and 28 days after implantation, no exuberant fibrosis and no multinucleated giant cells were visible in the grafted area, hence demonstrating the absence of foreign body reaction and the biocompatibility of these scaffolds

Cyto- and bio-compatibility assessment of plasma-treated polyvinylidene fluoride scaffolds for cardiac tissue engineering

International audienceAs part of applications dealing with cardiovascular tissue engineering, drop-cast polyvinylidene fluoride (PVDF) scaffolds have been treated by cold plasma to enhance their adherence to cardiac cells. The scaffolds were treated in a dielectric barrier device where cold plasma was generated in a gaseous environment combining a carrier gas (helium or argon) with/without a reactive gas (molecular nitrogen). We show that an Ar-N2 plasma treatment of 10 min results in significant hydrophilization of the scaffolds, with contact angles as low as 52.4° instead of 132.2° for native PVDF scaffolds. Correlation between optical emission spectroscopy and X-ray photoelectron spectroscopy shows that OH radicals from the plasma phase can functionalize the surface scaffolds, resulting in improved wettability. For all plasma-treated PVDF scaffolds, the adhesion and maturation of primary cardiomyocytes is increased, showing a well-organized sarcomeric structure (α-actinin immunostaining). The efficacy of plasma treatment was also supported by real-time PCR analysis to demonstrate an increased expression of the genes related to adhesion and cardiomyocyte function. Finally, the biocompatibility of the PVDF scaffolds was studied in a cardiac environment, after implantation of acellular scaffolds on the surface of the heart of healthy mice. Seven and 28 days after implantation, no exuberant fibrosis and no multinucleated giant cells were visible in the grafted area, hence demonstrating the absence of foreign body reaction and the biocompatibility of these scaffolds

Covalent shaping of polyoxometalate molecular films onto ITO electrodes for charge trapping induced resistive switching

International audienceAs nano-sized molecular oxides, polyoxometalates (POMs) hold great promise in non-volatile memory materials based on redox-active molecules. Materials processed from solution, by drop-casting, by embedding POMs in polymers, or using Layer-by-Layer deposition techniques have thus been reported and successfully investigated. Almost all these examples are electrostatically assembled materials. We herein propose an original route to the elaboration of robust covalent POM networks, to seek the influence of the shaping process on the POM-to-POM communication and the final device performance. Capitalizing on our experience in the handling of organic-inorganic POM hybrids, we have prepared diazonium hybrids to harness the propensity of diazonium salts to form multi-layered materials upon electrochemical reduction. A few nanometers thick materials have thus been grown onto ITO electrodes and have shown to be potentially suitable for Write-Once-Read-Many (WORM) devices, with a low set voltage

Ready-to-be-addressed oxo-clusters: individualized, periodically organized and separated from the substrate

International audienceThe first periodically organized individual polyoxometalates: from long-scale range to single-molecule level characterizations