Novel phosphate glasses with different amounts of TiO2 for biomedical applications Dissolution tests and proof of concept of fibre drawing

The aim of this work was to develop a range of phosphate glasses having different solubilities and with suitable characteristics to be drawn into fibres. Three glasses with molar compositions 50P(2)O(5)-30CaO-9Na(2)O-3SiO(2)-3MgO-(5-x)K2O-xTiO(2) (x = 0, 2.5, 5) were prepared and characterized in terms of thermal properties, density and dissolution rate. The dissolution tests were conducted in bi-distilled water (pH 6.0 +/- 0.5), Tris-HCl (pH 7.4 +/- 0.1) and citric acid buffer solutions (pH 3.0 +/- 0.1) in order to study the influence of pH on the dissolution process. TiO2 had a stabilizing effect on the glass, causing an increase in the glass transition temperature and density and a decrease in the glass dissolution rate. Acidic medium was found to strongly enhance the glass dissolution. The pH decrease caused by the acidic degradation products and the consequent enhancement of the glass weight loss were attenuated with the TiO2 increase. The fabrication of glass fibres using a preform drawing approach was investigated. Control and versatility of the process are demonstrated through the production of several tens of meters of fibre with diameters ranging from 37 +/- 2 mu m up to 173 +/- 7 mu m. Preliminary analysis reveal pristine fibres, free of crystallization, showing adequate flexibility for prospective biomedical applications. (C) 2010 Elsevier B.V. All rights reserved.