Pilot in vivo toxicological investigation of boron nitride nanotubes

Boron nitride nanotubes (BNNTs) have attracted huge attention in many different research fields thanks to their outstanding chemical and physical properties. During recent years, our group has pioneered the use of BNNTs for biomedical applications, first of all assessing their in vitro cytocompatibility on many different cell lines. At this point, in vivo investigations are necessary before proceeding toward realistic developments of the proposed applications. In this communication, we report a pilot toxicological study of BNNTs in rabbits. Animals were injected with a 1 mg/kg BNNT solution and blood tests were performed up to 72 hours after injection. The analyses aimed at evaluating any acute alteration of hematic parameters that could represent evidence of functional impairment in blood, liver, and kidneys. Even if preliminary, the data are highly promising, as they showed no adverse effects on all the evaluated parameters, and therefore suggest the possibility of the realistic application of BNNTs in the biomedical field

Thin Layer of Organosilane having specific foncitonality for the understanding of REE extraction

International audienc

Thin Layer of Organosilane having specific Functionality for the understanding of Rare Earth Element Extraction

International audienc

Surface response methodology for the study of supported membrane formation.

We report on the investigations of the formation of the tethered lipid bilayer by vesicle deposition on amine-functionalized surfaces. The tethered bilayer was created by the deposition of egg-PC vesicles containing 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-poly-(ethyleneglycol)-N-hydroxysuccinimide as anchoring molecules on an amine-coated surface. This approach is an easy route for the formation of a biomimetic- supported membrane. A Doelhert experimental design was applied to determine the conditions leading to the formation of a continuous and defect-free tethered bilayer on different surfaces (gold and glass). Doehlert designs allow modeling of the experimental responses by second-order polynomial equations as a function of experimental factors. Four factors expected to influence bilayer formation were studied: the lipid concentration in the vesicle suspension, the mass percentage of anchoring molecules in the vesicles, the contact time between the vesicles and the surface, and the resting time of the membrane after buffer rinse. The optimization of the membrane preparation parameters was achieved by monitoring lipid assembly formation using surface plasmon resonance spectroscopy on gold and by fluorescence recovery after photobleaching on glass. Three characteristic responses were systematically measured: the bilayer thickness, the lipid diffusion coefficient, and the lipid mobile fraction. The simultaneous inspection of the three characteristics revealed that a restricted experimental domain leads to properties that are in accordance with a bilayer presence. The factors of this domain are a lipid concentration from 0.1 to 1 mg/mL, 4-8% of anchoring molecules in the vesicles, 1-4 h of contact time between vesicles and surface, and 21-24 h of resting time after buffer rinse. Under these conditions, a membrane having a lipid mass per surface between 545 ± 5 and 590 ± 10 ng/cm2, a diffusion coefficient of between 2.5 ± 0.3 10 -8 and 3.60 ± 0.5 10-8 cm2/s, and a mobile fraction between 94 ± 2 and 99 ± 1% was formed. These findings were confirmed by atomic force microscopy observations, which showed the presence of a continuous and homogeneous bilayer in the determined experimental domain. This formation procedure presents many advantages; it provides an easily obtainable biomimetic membrane model for proteins studies and offers a versatile tethered bilayer because it can be adapted easily to various types of supports

Surface Properties of Alkoxysilane Layers Grafted in Supercritical Carbon Dioxide

International audienceSilicon oxide surface properties can be easily modified by grafting alkoxysilane molecules. Here, we studied the structure and the morphology of ultrathin layers prepared by the grafting of alkoxysilanes having different head groups (thiol, amine, and iodo) in supercritical carbon dioxide (CO2) on model plane silicon oxide surfaces. Several characterization techniques (X-ray reflectivity, water contact angle, X-ray photoelectron spectroscopy, and atomic force microscopy (AFM)) were used to determine the physicochemical properties of the layers prepared at different temperatures. Moreover, for the first time, AFM peak force measurements were used to delve deeper into the determination of the structure of these ultrathin alkoxysilane layers. The results show that the grafting temperature and the nature of the head group strongly affect the morphology and structure of the grafted layers. Dense monolayers are obtained with 3-(mercaptopropyl)trimethoxysilane at 60 °C, polycondensed layers are always prepared with [3-(aminoethylamino)propyl]trimethoxysilane, and a dense bilayer is synthesized with 3-(iodopropyl)triethoxysilane at 120 °C

Reactive Surface of Glass Particles Under Aqueous Corrosion

International audienceGlass dissolution rates are normalized to the glass surface area in contact with solution, and experiments are very often carried out using crushed and sieved materials whose size is narrowed between an upper and a lower value. Surface area of such particles could be determined by gas adsorption or geometric considerations. Although crushed particles cannot be assimilated with simple geometric shapes, rates normalized with—spheres of the same size—geometric surface area are underestimated but are close to those found for polished monoliths. Overestimation of the reactive surface when using gas adsorption measurements is discussed

Controlled Growth of a Photocatalytic Metal–Organic Framework on Conductive Plates by Mixing Direct Synthesis and Postsynthetic Modification Strategies

International audienceIn this work, we develop a two-step process for the controlled growth of a thin layer of a functionalized and photosensitive metal–organic framework (MOF), namely Ru–Ti–UiO-67, on the surface of a plate coated with indium tin oxide (ITO), a transparent conductive oxide (TCO). In the first step, the in situ controlled growth of a layer of UiO-67-based MOF doped with a photosensitizer (ruthenium complex), herein referred to as Ru–UiO-67, is carried out on the surface of the ITO-coated plate, leading to Ru–UiO-67/ITO. The obtained MOF layer is relatively thin, allowing increased interactions between the MOF material and the TCO surface, and consists of crystals in the near-nanometer particle size. In the second step, a postsynthetic modification (PSM) process is applied to Ru–UiO-67/ITO to integrate Ti catalytic sites into the MOF framework, leading to Ru–Ti–UiO-67/ITO (containing both the photosensitizer and catalyst) while maintaining the MOF’s structure and morphology in addition to its strong interaction with the substrate. Importantly, on the synthetic level, this work demonstrates the possibility to form a homogeneous surface anchored with MOF on a transparent conductive surface, whereby the obtained MOF layer is strongly bound to the substrate and postsynthetic chemical modifications are enabled without any loss of material. Furthermore, the obtained material is proven to exhibit an efficient visible-light-driven photodegradation activity in aqueous solution

Solar absorbers based on electrophoretically deposited carbon nanotubes using pyrocatechol violet as a charging agent

Carbon nanotubes (CNTs), deposited by electrophoretic deposition (EPD), are investigated as selective solar absorbers. First, various kinds of CNTs with different aspect ratios, are dispersed by ultrasound in an aqueous solution of pyrocatechol violet (PV). PV couples to the CNT´s outer walls via π-π stacking interactions and acts as a dispersing agent as well as a charging agent. PV adsorption isotherms on CNT combined with N2 physisorption isotherms are performed to optimize the CNT/PV ratio. In this way, Zeta potentials up to -40 mV are obtained for the dispersed CNTs, which are deposited on platinized silicon wafers by EPD, forming a film. The EPD kinetics are then investigated as a function of the applied electric field (in the 8?20 V cm−1 range) and are explained through a Sarkar & Nicholson model type. X-ray reflectivity is performed to characterize the density around 1.3 g cm−3, and film cohesion is probed by nanoindentation coupled to atomic force microscopy images. The hemispherical reflectance of the samples is measured by spectrophotometers equipped with an integrating sphere, and following from spectra, the absorptance (α) and emittance (ԑ) are calculated. The selectivity of the deposits, based on α and ԑ values, is then discussed as a function of the applied electric field and the coating thickness. Single-walled CNT deposits, at best, are found to have a solar absorptance of 0.91 and thermal emission of 0.05. Thermal annealing experiments reveal that the coatings could withstand up to 300 °C while sustaining selective properties and losing only 21% of the initial yield.Fil: Didier, Florian. Université Montpellier II; Francia. Centre National de la Recherche Scientifique; FranciaFil: Alastuey, Patricio. Université Montpellier II; Francia. Universidad Nacional de Tucumán. Instituto de Física del Noroeste Argentino. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Física del Noroeste Argentino; Argentina. Centre National de la Recherche Scientifique; FranciaFil: Tirado, Monica Cecilia. Universidad Nacional de Tucumán. Instituto de Física del Noroeste Argentino. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Física del Noroeste Argentino; ArgentinaFil: Odorico, Michaël. Université Montpellier II; Francia. Centre National de la Recherche Scientifique; FranciaFil: Deschanels, Xavier. Université Montpellier II; Francia. Centre National de la Recherche Scientifique; FranciaFil: Toquer, Guillaume. Université Montpellier II; Francia. Centre National de la Recherche Scientifique; Franci

Glass dissolution rate measurement and calculation revisited

International audienc