Nueva ruta para la obtención de materiales de composición eutéctica dentro de sistema Wollastonita-Fosfato Tricálcico

Tesis doctoral inédita. Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Inorgánica. Fecha de lectura: 25-05-201

Estudios "in vitro" de biomateriales de composición eutéctica en el sistema fosfato tricálcico-wollastonita

4 páginas, 5 figuras.-- Comunicación presentada al XI Congreso Nacional de Materiales celebrado en Zaragoza (Españ) del 23 al 25 de Junio de 2010.En el presente trabajo se ha seleccionado la composición eutéctica del sistema fosfato tricálcico - wollastonita, obteniéndose un vidrio por fusión y colado; y un material vitrocerámico por desvitrificación controlada del vidrio en masa. Ambos materiales se han caracterizado desde el punto de vista físico-químico y microestructural. La bioactividad se ha estudiado “in vitro” en suero fisiológico artificial (SFA) y en cultivos celulares. Los resultados indican que tanto el vidrio, como el vitrocerámico, presentan bioactividad en SFA y biocompatibilidad en cultivos celulares.Peer reviewe

Bioactivity modulation of Bioglass ® powder by thermal treatment

cited By 7International audienceA discussion of the effects of Bioglass ® powder crystallisation on the in vitro bioactivity in simulated body fluid (SBF) is presented. Starting from Bioglass ® powder, different glass-ceramics were obtained by thermal treatments between 580°C and 800°C, with variable crystallisation content (from 10 to 92wt%). All samples (glass and glass-ceramics) showed apatite formation at their surface when immersed in SBF. In case of the glass and the samples with lowest crystallinity, the first step of apatite formation involved a homogenous dissolution followed by an amorphous calcium phosphate (CaP) layer precipitation. For the samples with a high crystallisation content, heterogeneous dissolution occurred. For the first time, the Stevels number of the amorphous phase is used to explain the possible dissolution of the crystalline phase present in materials with a similar chemical composition of the Bioglass ®. All samples presented at 21 days of immersion in SBF B-type hydroxycarbonate apatite crystals. © 2012 Elsevier Ltd

Structural changes during crystallization of apatite and wollastonite in the eutectic glass of Ca3(PO4)2-CaSiO3 system

In this study, a bioactive glass of eutectic composition based on Ca(PO)-CaSiO system was prepared and investigated. It was found that by controlling the nucleation and growth of crystals, a glass-ceramics free from cracks, containing one or two crystalline phases, and of controlled nano- to microscale microstructure can be obtained. Heat treatment of the parent glass produces various calcium phosphates (Ca-deficient apatite and α-tricalcium phosphate) and calcium silicates (pseudo-wollastonite and/or wollastonite-2M) plus amorphous phases. By combining a number of experimental techniques like P and Si magic angle spinning nuclear magnetic resonance spectroscopy, scanning and transmission electron microscopy, energy-dispersive X-ray spectrometry, and Rietveld analysis of X-ray diffraction patterns, a crystallization model was derived, capable of explaining the observed structural and microstructural changes. The determination of amorphous or crystalline phases enabled to produce time-temperature-transformation plots. The structural role on the behavior of these materials and its impact on their in vitro bioactivity are also discussed.The authors acknowledge support of the E.U. COST Action MP 1301 Newgen (http://www.cost-newgen.org/)

Model Composites Based on Poly(lactic acid) and Bioactive Glass Fillers for Bone Regeneration

Poly(l-lactide-co-d,l-lactide) PDLA/45S5 Bioglass® (BG) composites for medical devices were developed using an original approach based on a thermal treatment of BG prior to processing. The aim of the present work is to gain a fundamental understanding of the relationships between the morphology, processing conditions and final properties of these biomaterials. A rheological study was performed to evaluate and model the PDLA/BG degradation during processing. The filler contents, as well as their thermal treatments, were investigated. The degradation of PDLA was also investigated by Fourier transform infrared (FTIR) spectroscopy, size-exclusion chromatography (SEC) and mechanical characterization. The results highlight the value of thermally treating the BG in order to control the degradation of the polymer during the process. The present work provides a guideline for obtaining composites with a well-controlled particle dispersion, optimized mechanical properties and limited degradation of the PDLA matrix