Ion release from SrO-CaO-TiO2-P2O5 glasses in Tris buffer solution

Abstract

SrO-containing calcium phosphate invert glasses, (60-x)CaO·xSrO·30P2O5·7Na2O·3TiO2 (mol%, x = 0-60), which are expected to inhibit bone resorption by osteoclast and enhance bone formation, were prepared and their ion release behaviors in Tris buffer solution were estimated. The glass containing 20 mol% of SrO showed the smallest amount of the dissolved ions in the present work. Laser Raman spectra showed that the peaks of phosphate groups and TiOy polyhedral groups red-shifted with increasing the SrO content in the glasses. The shift was suggested to be due to decrease in bonding strength between cations and phosphate groups or TiOy polyhedral groups in the glasses. In the case of the glasses containing SrO over 20 mol%, no shifts of Raman peaks due to the TiOy polyhedra were observed. The TiOy (y = 4 or 6) polyhedra in the glasses can coordinate with cations up to 18 mol% since they contain 3 mol% of TiO2. Sr2+ ions are supposed from the shift behavior of the Raman peaks to preferentially coordinate with the TiOy polyhedra; the formation of this structure would induce decrease in the ion amounts released from the glasses containing 0-20 mol% of SrO.