S. Hayakawa et al., P-31 MAS-NMR STUDIES OF PHOSPHATE SALTS FORMATION ON CALCIUM-CONTAINING OXIDE GLASSES IN A SIMULATED BODY-FLUID, Nippon Seramikkusu Kyokai gakujutsu ronbunshi, 104(11), 1996, pp. 1000-1003
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.