X-ray microanalysis in STEM of short-term physico-chemical reactions at bioactive glass particles / biological fluids interface. Determination of O/Si atomic ratios

Short-term physico-chemical reactions at the interface between bioactive glass particles and biological fluids are studied and we focus our attention on the measurements of O/Si atomic ratio. The studied bioactive glass is in the SiO2-Na2O-CaO-P2O5-K2O-Al2O3-MgO system. The elemental analysis is performed at the submicrometer scale by STEM associated with EDXS and EELS. We previously developed an EDXS quantification method based on the ratio method and taking into account local absorption corrections. In this way, we use EELS data to determine, by an iterative process, the local mass thickness which is an essential parameter to correct absorption in EDXS spectra. After different delays of immersion of bioactive glass particles in a simulated biological solution, results show the formation of different surface layers at the bioactive glass periphery. Before one day of immersion, we observe the presence of an already shown (Si,O,Al) rich layer at the periphery. In this paper, we demonstrate that a thin electron dense (Si,O) layer is formed on top of the (Si,O,Al) layer. In this (Si,O) layer, depleted in aluminium, we point out an increase of oxygen weight concentration which can be interpreted by the presence of Si(OH)4 groups, that permit the formation of a (Ca,P) layer. Aluminium plays a role in the glass solubility and may inhibit apatite nucleation. After the beginning of the (Ca,P) layer formation, the size of the electron dense (Si,O) layer decreases and tends to disappear. After two days of immersion, the (Ca,P) layer grows in thickness and leads to apatite precipitatio

Viols-en-Laval – Habitat de Cambous

Le site de Cambous est un habitat la culture de Fontbouisse (seconde moitié du troisième millénaire) présentant une vingtaine de bâtiments en pierres sèches dont les bases des murs sont conservées. Ils se répartissent en deux groupes, les hameaux A et B. Le site a été exploré sur un tiers de sa surface jusqu’à la fin des années quatre-vingt par H. Canet et J.-L. Roudil. Les fouilles ont repris en 2014, dans le cadre du programme de recherche de l’équipe Sociétés de la Préhistoire et de la Pro..

New Strontium-based Bioactive Glasses: Physicochemical Reactivity and Delivering Capability of Biologically Active Dissolution Products

International audienceThe development of bone tissue regeneration calls for biomaterials able to release biologically active substances in a controlled manner after implantation. In this context, strontium-doped bioactive glasses are of major interest; their key property relies on the increased kinetics of surface reactions, along with the release of critical concentrations of ionic dissolution products capable of stimulating cellular responses. In this paper, we report a complete evaluation of the in vitro reactivity of new SiO2–CaO–SrO and SiO2–CaO–P2O5–SrO bioactive glasses. In contact with simulated acellular physiological fluids, these materials induce the formation of a calcium phosphate surface layer that closely resembles to the biological apatite present in bones. Compared to strontium-free materials, the dissolution of SiO2–CaO–SrO and SiO2–CaO–P2O5–SrO glasses is reduced. However the surface layer is more quickly transformed into a bone-like apatite phase, according to the kinetics of evolution of the Ca/P atomic ratio. Evidences of the presence of Sr at the glass/biological fluids interface were obtained, along with the demonstration that this element is released in physiological concentrations into the biological environment. Knowing the well-recognized beneficial effects of strontium on cell activity and bone remodeling, this crucial result gives high hopes for the development of innovative applications based on Sr-doped glasses in treatment of osteoporosis and tissue engineering

Micro-PIXE-RBS methods highlighting the influence of phosphorus on the in vitro bioactivity of sol-gel derived glass particles in the SiO2-CaO-P2O5 system

International audienc

Archéologie et diversité culturelle

C’est en opposant les singularités qu’on comprend la richesse de l’universel. L’humanité n’est pas une fourmilière mais l’expression d’une diversité… Le fait d’être de quelque part donne conscience que chaque homme est un centre du monde.Félix Marcel Castan Ainsi je suis responsable pour moi-même et pour tous, et je crée une certaine image de l’homme que je choisis ; en me choisissant, je choisis l’homme.Jean-Paul Sartre Entre la fuite et la quête Le mot « diversité » se rapporte à des domain..

Influence of mesostructuration on the reactivity of bioactive glasses in biological medium: a PIXE-RBS study

Building mesostructured biomaterials is a challenging and exciting task that has attracted much attention because of their use as drug carriers or drug delivery systems. In the case of bioactive materials, the mesostructuration can also deeply impact their physico-chemical properties and the reactivity. In this study, we show how highly ordered mesoporosity influences the early steps of the biomineralization process and the reactivity in binary (SiO2–CaO) and ternary (SiO2–CaO–P2O5) bioactive glasses. Conventional porous sol–gel glasses were synthesized using a classical route, while mesostructured glasses were developed using a non-ionic surfactant. Textural properties of these materials have been characterized. The in vitro biomineralization process was followed, using Particle Induced X-ray Emission (PIXE) associated to Rutherford Backscattering Spectrometry (RBS), which are efficient methods for a highly sensitive multi-elemental analysis. Elemental maps of silicon, calcium and phosphorus were obtained at a micrometer scale and revealed for the first time a bulk reactivity for mesostructured glasses. This is a major advantage over conventional glasses, for which the first steps of biomineralization are limited to the periphery of the material. Their enhanced bioactivity combined with their possible use as drug-delivery systems make them promising candidates for bone regeneration

Properties of two biological glasses used as metallic prosthesis coatings and after an implantation in body

présentation faite par Y. Barbottea

Atomic transfers between implanted bioceramics and tissues in orthopaedics surgery

We study transfers of ions and debris from bioceramics implanted in bone sites. A contamination of surrounding tissues may play a major role in aseptic loosening of the implant. For these reasons, bioceramics require studies of biocompatibility and biofunctionality . So, in addition to in vitro studies of bioceramics, it is essential to implant them in vivo to know body reactions. We measured the concentration of mineral elements at different time intervals after implantation over a whole cross-section. We found a discontinuity of the mineral elements (Ca, P, Sr, Zn, Fe) at the interface between the implant and the receiver. The osseous attack is not global but, on the contrary, centripetal. Moreover, the fit of the concentration time course indicates that the kinetics of ossification is different for each atomic element and characterizes a distinct biological phenomeno