Analysis of the dissolution and bioactivity of bioactive glasses based on the system SiO2-CaO-P2O5 doped with silver

Abstract

The advance of life expectation as a consequence from medical progress comes along with an increasing number of bone fractures, which turns interesting the improvement of the biomaterials, especially the bioactive glasses. Such materials act through internal and external stimuli and participate on the regeneration of the damaged bone tissue; they also interact with the body fluid, inducing the nucleation of an artificial layer of hydroxyapatite when in a host tissue, which avoids that the material comes to be rejected by the body. Because of the amorphous nature of the glass, it is possible to arrange ions on its structure. These ions might have biological activity and play different roles on a living body. With the purpose of allying antimicrobial properties to this material, the bioglass can be doped with silver, in non-toxical concentrations. This project proposes the analysis of the dissolution of bioglasses based on SiO2-CaO-P2O5 doped with silver (in different concentrations), aiming to study the influence of the silver valence (+1 or 0) on the material's structure and dissolution and, this way, making it possible to predict biological responses and evaluate the biological activity. The dissolution tests and the kinetic analysis of the dissolution will be performed according to ISO 10993-14 in different temperatures making it possible to use the Arrhenius equation to determinate the enthalpy of dissolution of the glasses. The microstructural characterization of the glasses will be made before and after the dissolution tests, using the techniques of Fourier transform infrared spectrometry, X ray diffraction and scanning electron microscopy, which will allow the understanding of the influence of the dissolution on the chemical transformations of the glass. Finally, the structural modifications and the silver influence in the processes will be related to the dissolution of the material. (AU)