P2O5 SBF paper; MDO 1 THE EFFECT OF PHOSPHATE CONTENT ON THE BIOACTIVITY OF SODA-LIME- PHOSPHOSILICATE GLASSES

We report on the bioactivity of two series of glasses in the SiO2-Na2O-CaO-P2O5 system after immersion in simulated body fluid (SBF) after 21 days. The effect of P2O5 content was examined for compositions containing 0 to 9.25 mol. % phosphate. Both series of glasses degraded to basic pH, but the solutions tended towards to neutrality with increasing phosphate content; a result of the acidic phosphate buffering the effect of the alkali metal and alkaline earth ions on degradation. Bioactivity was assessed by the appearance of features in the X-ray diffraction (XRD) traces and Fourier transform infrared (FTIR) spectra consistent with crystalline hydroxyl-carbonate-apatite (HCAp): such as the appearance of the (002) Bragg reflection in XRD and splitting of the P-O stetching vibration around 550 cm-1 in the FTIR respectively. All glasses formed HCAp in SBF over the time periods studied and the time for formation of this crystalline phase occurred more rapidly in both series as the phosphate contents were increased. For P2O5 content> 3 mol. % both series exhibited highly crystalline apatite by 16 hours immersion in SBF. This indicates that in the compositions studied, phosphate content is more important for bioactivity than network connectivity (NC) of the silicate phase an