Resorbable Glass-Ceramic Phosphate-Based Scaffolds for Bone Tissue Engineering: Synthesis, Properties and In Vitro Effects on Human Marrow Stromal Cells

Highly porous bioresorbable glass-ceramic scaffolds were prepared via sponge replication method by using an open-cell polyurethane foam as a template and phosphate-based glass powders. The glass, belonging to the P2O5-SiO2-CaO-MgO-Na2O-K2O system, was synthesized by a melting-quenching route, ground, and sieved to obtain powders with a grain size of less than 30\u2009\u3bcm. A slurry containing glass powders, polyvinyl alcohol, and water was prepared to coat the polymeric template. The removal of the polymer and the sintering of the glass powders were performed by a thermal treatment, in order to obtain an inorganic replica of the template structure. The structure and properties of the scaffold were investigated from structural, morphological, and mechanical viewpoints by means of X-ray diffraction, scanning electron microscopy, density measurements, image analysis, and compressive tests. The scaffolds exhibited a trabecular architecture that closely mimics the structure of a natural spongy bone. The solubility of the porous structures was assessed by soaking the samples in acellular simulated body fluid (SBF) and Tris-HCl for different time frames and then by assessing the scaffold weight loss. As far as the test in SBF is concerned, the nucleation of hydroxyapatite on the scaffold trabeculae demonstrates the bioactivity of the material. Biological tests were carried out using human bone marrow stromal cells to test the osteoconductivity of the material. The cells adhered to the scaffold struts and were metabolically active; it was found that cell differentiation over proliferation occurred. Therefore, the produced scaffolds, being biocompatible, bioactive, resorbable, and structurally similar to a spongy bone, can be proposed as interesting candidates for bone grafting

GLASS SURFACES - 1982

Une nouvelle catégorie de surface des verres est décrite. Les surfaces du type IIIB sont constituées par des couches multiples d'oxydes, hydroxydes et des silicates hydratés, provenant des réactions de précipitation entre la surface du verre et la solution de lixiviation. Les très faibles vitesses de lixiviation ainsi que les faibles épaisseurs d'érosion pour certaines compositions des verres complexes de déchets nucléaires sont principalement dues à une surface du type IIIB. Les limites de solubilité qui établissent l'équilibre des concentrations ioniques pour les eaux d'immersion, établissent aussi les multiples barrières de couches du type IIIB qui protègent les verres de déchets nucléaires en contact avec ces eaux d'immersion.A new category of glass surface is described. Type IIIB surfaces are composed of multiple layers of oxides, hydroxides, and hydrated silicates resulting from a sequence of solution-precipitation reactions between the glass surface and leaching solutions. Very low leach rates and then ion depletion depths of certain compositions of complex nuclear waste glasses are due to Type IIIB surfaces. The solubility limits that establish the equilibrium ionic concentrations for burial ground waters also establish the multiple barrier Type IIIB films, to protect nuclear waste glasses in contact with those ground waters

Principles of electronic ceramics

xviii+546hlm.;25c

Principles of Electronic Ceramics

xviii., 546 hal., ill., 23 c