  Mesoporous bioactive glasses (MBGs) in the system SiO2-CaO-P2O5-Ga2O3 have
been synthesized by the evaporation induced self-assembly method and subsequent
impregnation with Ga cations. Two different compositions have been prepared and
the local environment of Ga(III) has been characterized using 29Si, 71Ga and
31P NMR analysis, demonstrating that Ga(III) is efficiently incorporated as
both, network former (GaO4 units) and network modifier (GaO6 units). In vitro
bioactivity tests evidenced that Ga-containing MBGs retain their capability for
nucleation and growth of an apatite-like layer in contact with a simulated body
fluid with ion concentrations nearly equal to those of human blood plasma.
Finally, in vitro cell culture tests evidenced that Ga incorporation results in
a selective effect on osteoblasts and osteoclasts. Indeed, the presence of this
element enhances the early differentiation towards osteoblast phenotype while
disturbing osteoclastogenesis. Considering these results, Ga-doped MBGs might
be proposed as bone substitutes, especially in osteoporosis scenarios.

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