Predicting bioactive properties of phosphosilicate glasses using mixture designs

Two mixture designs have been applied to bioactive phosphosilicate glasses in the range 42–55% SiO2, 13.5–48% CaO, 0–35% Na2O and 0–5% P2O5 (mol%). With this mathematical method, the hydroxyapatite formation time and the thickness of this precipitated CaP phase after 15 days of soaking in a simulated body fluid can be predicted. The apatite formation time is obtained by Fourier Transform Infra Red Spectroscopy (FTIR) and the thickness of the hydroxyapatite layer is measured with Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (SEM–EDS). Two equations are obtained, correlating the two properties with the molar composition of glasses. The two designs developed in this paper allow pointing out several compositions potentially more interesting than Henchʹs 45S5. Among them, two compositions, named D47 and D46.5, have been subjected to water contact angle measurements and cell viability tests and compared to 45S5 in order to attest of their biological interest.