Niobium-Containing Phosphate Glasses Prepared by the Liquid-Phase Method.

Phosphate invert glasses (PIGs) have been attracting attention as materials for bone repair. PIGs have a high flexibility in chemical composition because they are composed of orthophosphate and pyrophosphate and can easily incorporate various ions in their glass networks. In our previous work, incorporation of niobium (Nb) into melt-quench-derived PIGs was effective in terms of controlling their ion release, and Nb ions promoted the activity of osteoblast-like cells. In the present work, a liquid-phase method was used for synthesizing Nb-containing PIGs, as this method allows us to prepare a glass precursor solution at room temperature, which can be attributed to improved glass-shape design. Nb-containing PIGs were successfully prepared, and their ion release behavior was controlled by changing the Nb content in the PIGs. The functions of Nb varied according to its content. For example, in the case of PIGs containing a larger amount of Nb, Nb acted as both the network modifier and former while also inducing the formation of chain-like structures. These glasses possessed a gradual ion release in a tris-HCl buffer solution. Cotton-wool-like structured scaffolds were fabricated using the synthesized Nb-containing glass using a wet-spinning method. Because the scaffolds possess excellent flexibility and controllable ion release, they are good candidates for new biomaterials.