P-31 MAS-NMR STUDIES OF PHOSPHATE SALTS FORMATION ON CALCIUM-CONTAINING OXIDE GLASSES IN A SIMULATED BODY-FLUID

P-31 MAS-NMR spectra were measured for pulverized binary and ternary g lasses containing Ca2+ ions after soaking in a simulated body fluid (K okubo solution; pH=7.25) for 1 d, and the chemical state of adsorbed p hosphate ions were examined. The P-31 chemical shift indicated that or thophosphate ions, H2PO4-(3-x) (0<x<3), were adsorbed on all the glass es but 60CaO . 40Al(2)O(3); pyrophosphate ions, H2P2O7-(4-x) (0<z<4), were detected on the aluminate glass, indicating that orthophosphate i ons in the Kokubo solution were dimerized on the glass surface. For th e glasses such as 60CaO . 40Al(2)O(3), 40CaO . 60B(2)O(3), 40CaO . 30B (2)O(3) . 30Al(2)O(3) and 40CaO . 30B(2)O(3) . 30SiO(2), those phospha te ions gave broad P-31 MAS-NMR spectra, hence have a broad distributi on by coordinating to the various surface sites of the glasses. On the other hand, sharp P-31 MAS-NMR spectra as for a cortical bone (rabbit ) were obtained for the rest of the glasses, (CaO)-Ca-50 . 50SiO(2) an d 40CaO . 30B(2)O(3) . 30TiO(2), on which apatite formed in shorter so aking period in the Kokubo solution. It was thus concluded that presen ce of orthophosphate ions on the glass surfaces favored the deposition of apatite.