| Abstract
| - The local structures of highly ordered mesoporous bioactive CaO−SiO2−P2O5 glasses were investigated forvariable Ca contents. 1H NMR revealed a diversity of hydrogen-bonded and “isolated” surface silanols aswell as adsorbed water molecules. The structural roles of Si and P were explored using a combination of 29Siand 31P magic-angle spinning (MAS) nuclear magnetic resonance (NMR) techniques; the proximities of Siand P to protons were studied through cross-polarization-based experiments, including 1H−29Si and 1H−31Phetero-nuclear two-dimensional correlation spectroscopy. The results are consistent with SiO2 being the mainpore-wall component, whereas P is present as a separate amorphous calcium orthophosphate phase, which isdispersed over the pore wall as nanometer-sized clusters. The excess Ca that is not consumed in the phosphatephase modifies the silica glass network where it associates at/near the mesoporous surface. This biphasicstructural model of the pore wall leads to the high accessibility of both Ca and P to body fluids, and itsrelation to the experimentally demonstrated high in vitro bioactivities of these materials is discussed.
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