Key Engineering Materials Vols. 361-363

Abstract: Niobo-phosphate glasses were produced in order to assess the citotoxicity of samples with different compositions. Different P2O5/Ca ratios were studied in an attempt to correlate the biological behavior of new niobo-phosphate bioactive glasses with conventional bioactive calcium phosphate glasses. The most biocompatible glass composition was chosen to produce glassreinforced hydroxyapatite composites.

Abstract: Glass-ceramic scaffolds for bone grafting have been prepared using the sponge replication method and a highly bioactive silica based glass belonging to the system SiO2-P2O5- CaO-MgO-Na2O-K2O (CEL2). The parameters for the sponge impregnation were optimized in order to obtain a continuous coating of the polymeric skeleton which will lead, after the polymeric phase removal, to a resistant macroporous glass-ceramic template. A complete characterization was carried out on the obtained scaffold in order to assess its morphology and specifically its porosity and the degree of pores interconnection. A human osteoblasts cells line (MG-63) was cultured onto the scaffold and the effect of stimulation with shock waves on the cell ability of colonizing the scaffold was investigated.

Abstract: In this work a new kind of CaSiO3-doped α-Ca3(PO4)2 ceramic materials, with compositions lying outside the field of the Ca3(PO4)2 solid solution in the system Ca3(PO4)2- CaSiO3, were obtained and some of their properties, relevant for bone repairing, were studied in vitro. Crystalline α-Ca3(PO4)2 solid solution and minor amounts of non-equilibrium residual glass were the only phases in the materials containing 2 and 5 wt% of CaSiO3. α-Ca3(PO4)2, crystalline eutectic-like phase and residual glass were observed for sample containing 15 and 20 wt% of CaSiO3. The mechanical strength improved for all the doped ceramics with regard to un-doped Ca3(PO4)2. The release of ionic Ca and Si in simulated physiological conditions increased with the content of CaSiO3 and favored α-Ca3(PO4)2 surface transformation. The soluble components extracted from the CaSiO3-doped α-Ca3(PO4)2 bioceramics were not cytotoxic to human fibroblastlike cells. Initial cell adhesion onto the surface of the materials seemed to be partially hindered by surface reactivity and remodeling, however those cells adhered to the experimental bioceramics were viable and proliferated normally.

Abstract: In this work, a new bioresorbable phosphate glass (I-CEL2) was prepared in order to use it for the production of 3D-bioresorbable scaffold for bone regeneration. I-CEL2 was characterized to assess its thermal characteristics as well as its bioresorption rate in different medium such as distilled water, Tris-HCl and Simulated Body Fluid (SBF). 3D-macroporous scaffolds were prepared by mixing and pressing I-CEL2 powders and an organic phase and by treating the compact of powders at 550°C for 3 hours. The obtained scaffolds showed a very high porosity and a high resorption rate and are thus suitable candidates for a scaffold to be used as a temporary guide for bone regeneration. The initial response of human marrow stromal cells (hMSCs) has been tested on I-CEL2 surface to describe its biological potential.

Abstract: Bioglass films were prepared by reactive magnetron sputtering from a 45S5 target and than annealed in air up to 550 oC in order to relax the mechanical stresses. The mixtures (0, 7 and 15%) of oxygen and argon were used in order to modify the films stoichiometry. Morphological and compositional studies were performed by SEM coupled with an EDAX system. FTIR and micro Raman measurements were performed in order to investigate the molecular vibrations of the BG structure. A modified composition respect to the target one was found for all the films, with lower silicon dioxide concentrations. The films displayed rough surfaces with spherical particles of 10-20 μm diameter embedded in the surfaces. The Raman results evidenced important carbonate lines besides the silica-phosphate bands.

Abstract: Apatite forming and bonding ability of Ti based bulk metallic glass ((Ti0.40Zr0.10Cu0.36Pd0.14)99Ca1: BMG) were investigated as a new type of biomaterials. Powder mixture of CaHPO4･2H2O and Ca(OH)2 and the BMG disks were treated with autoclave for hydrothermal hot-pressing simultaneously (150°C, 40MPa). And then the BMG disks were soaked in simulated body fluid (SBF, Kokubo solution). Apatite were deposited and covered on the surface of the BMG. It was firstly demonstrated that surface of Ti based bulk metallic glass could be revealed apatite forming ability.

Abstract: The RF magnetron sputter technique was used to deposit Bioglass (BG) and hydroxyapatite (HA) coatings onto titanium substrates. The aim of this study was evaluated the growth behavior of rat bone marrow cells of various deposited coatings. The EDS measurements demonstrated that the composition BG coating was changed during magnetron sputtering. The rat bone marrow derived osteoblast-like cells showed improved osteogenic response on crystalline magnetron sputtered HA coatings compared BG coatings. Scanning electron microscopical examination showed an extensive mineralization after 16 days of culture, while on the surface of the BG coating only a multilayer without mineralization could be observed.

Abstract: The results of a combined structural characterisation (XRD, IR, NMR, SEM, TEM) of a phosphate containing Mg-Ca silicate and a phosphate containing Na-Ca silicate glass samples are presented. The structural results are also compared with in vitro tests carried out in simulated body fluids for checking bioactivity.

Abstract: The aim of this study is to investigate the crystallization behavior and in-vitro bioactivity character of glass ceramics having 3:7 weight ratio of fluorapatite (Ca10(PO4)6F2) to potassium mica (K2Mg3AlSi3O10F2) as a function of cerium oxide addition, and compare the morphology of hydroxycarbonate apatite (HCA) layer formation depending on cerium oxide addition.

Abstract: In this study, we report on the effect of Bioglass® structural transformations on its sintering behaviour. In a previous paper, we showed that while heating up to 1000°C, five successive transformations occur: glassy transition, phase separation, two crystallization processes and a second glassy transition. The sintering of the material exhibits two main shrinkage stages associated to the two glassy transitions at 550°C and 850°C. At 580°C, the glass-in-glass phase separation induces a decrease of the sintering rate immediately followed by the crystallisation of the major phase Na2CaSi2O6 between 600 and 700°C, from the surface to the bulk of the particles. A completed inhibition of sintering takes place followed by a minor shrinkage due to volume crystallization. A plateau is observed until the second glassy transition.