7 research outputs found
Polymer coated cerium oxide nanoparticles as oxidoreductase-like catalysts
Cerium oxide nanoparticles have been shown to mimic oxidoreductase enzymes by
catalyzing the decomposition of organic substrates and reactive oxygen species.
This mimicry can be found in superoxide radicals and hydrogen peroxides,
harmful molecules produced in oxidative stress asso-ciated diseases. Despite
the fact that nanoparticle functionalization is mandatory in the context of
nanomedicine, the influence of polymer coatings on their enzyme-like catalytic
activity is poorly understood. In this work, six polymer coated cerium oxide
nanoparticles are prepared by associa-tion of 7.8 nm cerium oxide cores with
two poly(sodium acrylate) and four poly(ethylene glycol) (PEG) grafted
copolymers with different terminal or anchoring end groups, such as phosphonic
acids. The superoxide dismutase-, catalase-, peroxidase- and oxidase-like
catalytic activities of the coated nanoparticles were systematically studied.
It is shown that the polymer coatings do not af-fect the superoxide
dismutase-like, impair the catalase-like and oxidase-like and surprisingly
im-proves peroxidase-like catalytic activities of cerium oxide nanoparticles.
It is also demonstrated that the particles coated with the PEG-grafted
copolymers perform better than the poly(acrylic acid) coated ones as
oxidoreductase-like enzymes, a result that confirms the benefit of having
phosphon-ic acids as anchoring groups at the particle surface.Comment: 23 pages, 8 figures, 3 table
Copolymérisation et télomérisation radicalaire de l'acide acrylique. Application à la synthèse de polyacrylates hydrosolubles biodégradables
MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF
Molecular Simulations of Thermo-Mechanical Properties of Epoxy-Amine Resins
International audienceAll-atom molecular dynamics simulations (MD) were performed with the CHARMM force field to characterise various epoxy resins, such as aliphatic or bisphenol-based ones. A multistep crosslinking algorithm was established and key properties such as density, glass temperature and elastic modulus, were calculated. A quantitative comparison was made and was proven to be in good agreement with experimental data, with average absolute deviations between experiments and molecular simulation comprised between 2% and 12%. Additional findings on structure-property relationships were highlighted such as the effect of the crosslinking rate and oligomerisation of the resin
Impact of the Force Field on the Calculation of Density and Surface Tension of Epoxy–Resins
International audienceThe molecular simulation of interfacial systems is a matter of debate because of the choice of many input parameters that can affect significantly the performance of the force field of reproducing the surface tension and the coexisting densities. After developing a robust methodology for the calculation of the surface tension on a Lennard-Jones fluid, we apply it with different force fields to calculate the density and surface tension of pure constituents of epoxy resins. By using the model that best reproduces the experimental density and surface tension, we investigate the impact of composition in mass fraction on uncured epoxy resins and the effects of degree of cross-linking on cured resins
Persistent luminescence nanoparticles functionalized by polymers bearing phosphonic acid anchors: synthesis, characterization, and in vivo behaviour
International audienceOptical in vivo imaging has become a widely used technique and is still under development for clinical diagnostics and treatment applications. For further development of the field, researchers have put much effort into the development of inorganic nanoparticles (NPs) as imaging probes. In this trend, our laboratory developed ZnGa1.995O4Cr0.005 (ZGO) nanoparticles, which can emit a bright persistent luminescence signal through the tissue transparency window for dozens of minutes and can be activated in vivo with visible irradiation. These properties endow them with unique features, allowing us to recover information over a long-time study with in vivo imaging without any background. To target tissues of interest, ZGO must circulate long enough in the blood stream, a phenomenon which is limited by the mononuclear phagocyte system (MPS). Depending on their size, charge and coating, the NPs are sooner or later opsonized and stored into the main organs of the MPS (liver, spleen, and lungs). The NPs therefore have to be coated with a hydrophilic polymer to avoid this limitation. To this end, a new functionalization method using two different polyethylene glycol phosphonic acid polymers (a linear one, later named lpPEG and a branched one, later named pPEG) has been studied in this article. The coating has been optimized and characterized in various aqueous media. The behaviour of the newly functionalized NPs has been investigated in the presence of plasmatic proteins, and an in vivo biodistribution study has been performed. Among them ZGOpPEG exhibits a long circulation time, corresponding to low protein adsorption, while presenting an effective one-step process in aqueous medium with a low hydrodynamic diameter increase. This new method is much more advantageous than another strategy we reported previously that used a two-step PEG silane coating performed in an organic solvent (dimethylformamide) for which the final hydrodynamic diameter was twice the initial diameter