A perfect pair: Niobium- and gallium-doped ceramic biomaterial enabled by coupled synthesis method with potential application for bone regeneration and cancer-targeted therapy

In this work, we report the synthesis and characterization of sol-gel bioactive glasses containing niobium (Nb) and gallium (Ga), a multifunctional glass that synergistically combines the respective effects of these species in potentiating bone repair and regeneration, concomitantly with a bone cancer targeted therapy. We found that the entry of Ga3+ into the vitreous network promotes an increase in the network connectivity, contributing to an increase in the degree of polymerization of the glass, since part of the calcium ions that behave as network modifying agents were replaced by gallium ions that act as network formers, and hence a replacement of part of the Si-O−…Ca2+…−O-Si by Si-O-Ga-O-Si bonds. Such results confirmed an increase in bridging oxygen bond density associated with a decrease in the number of bonds per unit volume of the glass due to the expansion of the glassy network. Furthermore, the incorporation of Ga2O3 at the expense of CaO in the composition of SNb3Ga3 decreased the ionicity of the chemical bonds. The study of pH variation revealed that the presence of Ga decreases the solubility of the glass influenced by a reduction in non-bridging oxygens (NBOs) concentration, which in turn is associated with an increase in glass network connectivity