Effect of Strontium Substitution on the Bioactive Properties and Microstructure of Borate-Based Bioglass

Borate-based bioglass has attract more interest as a bone repair material due to its good machinability and degradability, but the quick release of boron produce cytotoxicity is a question need be taken into consideration. In this paper, borate-based bioglass scaffolds substituted by 0-9 mol% strontium with a porous structure were prepared by a polymer foam replication technique. The effect of strontium substitute on the bioactive properties and microstructure of scaffolds were investigated by XRD, SEM, MTT, FTIR and MAS-NMR test. The results showed that the as-made bioglass were amorphous and had a porous structure similar to human trabecular bone. The bioglass in vitro bioactivity was observed by the conversion of the glass surface to a nanostructured hydroxyapatite layer in SBF. The substitution of strontium on borate-based bioglass keeps the B 3+ ions concentration in a proper range in some extent. According to the Fourier transform infrared and MAS-NMR spectrums, when the strontium increased, part of the silicate network structure in the glass is destroyed. Meanwhile, the layer structure containing [BO 3 ] gradually replaced by the framework structure containing [BO 4 ], this is the basic reason why the bioactive properties of borate-based glass changed with the substitution of strontium concentration