Fabrication and characterization of strontium-doped borate-based bioactive glass scaffolds for bone tissue engineering

Boron is an essential element for bone health, but its cytotoxicity depends on its concentration. In the present study, borate-based 13-93B2 glass scaffolds doped with varying amounts of strontium (0-9 mol.% Sr) with a porosity of 80% and pore size of 200-500 μm were prepared by a polymer foam replication technique. The effect of strontium content on the structure and bioactive properties of scaffolds were investigated by FTIR, XRD, ICP and MTT test. The results showed that the appearance of strontium in the glass has no obvious effect on the structure. The as-made scaffolds were amorphous and had a compressive strength of 11 MPa. The scaffolds in vitro bioactivity was observed by the conversion of the glass surface to a nanostructured hydroxyapatite layer in SBF. The increase of strontium concentration in borate-based glass accelerated the release of Si4+, Ca2+ ions, and significantly reduced the release of B3+ ions in some extent. The results indicated that borate-based bioactive glass doped with particular proportion of Sr suppressed the rapid release of boron and the cytotoxicity of glass scaffolds was minimized at least. This strontium-doped borate-based bioactive glass could be a potential scaffold material for bone tissue engineering.