Phosphate glass fibre scaffolds: Tailoring of the properties and enhancement of the bioactivity through mesoporous glass particles

Novel bone glass fibre scaffolds were developed by thermally bonding phosphate glass fibres belonging to the P2O5 - CaO - Na2O - SiO2 - MgO - K2O - TiO2 system (TiPS2.5 glass). Scaffolds with fibres of 85 or 110 μm diameter were fabricated, showing compressive strength in the range of 2-3.5 MPa, comparable to that of the trabecular bone. The effect of different thermal treatments and fibre diameters and length on the final scaffold structure was investigated by means of micro-CT analysis. The change of the sintering time from 30 to 60 minutes led to a decrease in the scaffold overall porosity from 58 to 21 vol.% when using the 85 μm fibre scaffold and from 50 to 40 vol.% when increasing the sintering temperature from 490 to 500 °C for the 110 μm fibre scaffold. The 85 μm fibres resulted in an increase of the scaffold overall porosity, increased pore size and lower trabecular thickness; the use of different fibre diameters allowed the fabrication of a scaffold showing a porosity gradient. In order to impart bioactive properties to the scaffold, for the first time in the literature the introduction in these fibre scaffolds of a bioactive phase, a melt-derived bioactive glass (CEL2) powder or spray-dried mesoporous bioactive glass particles (SD-MBG) was investigated. The scaffold bioactivity was assessed through soaking in simulated body fluid. CEL2/glass fibre scaffold did not show promising results due to particle detachment from the fibres during soaking in simulated body fluid. Instead the use of mesoporous bioactive powders showed to be an effective way to impart bioactivity to the scaffold and could be further exploited in the future through the ability of mesoporous particles to act as systems for the controlled release of drugs.