Optimising bioactive glass scaffolds for bone tissue engineering

A 3D scaffold has been developed that has the potential to fulfil the criteria for an ideal scaffold for bone tissue engineering. Sol–gel derived bioactive glasses of the 70S30C (70 mol% SiO2, 30 mol% CaO) composition have been foamed to produce 3D bioactive scaffolds with hierarchical interconnected pore morphologies similar to trabecular bone. The scaffolds consist of a hierarchical pore network with macropores in excess of 500 μm connected by pore windows with diameters in excess of 100 μm, which is thought to be the minimum pore diameter required for tissue ingrowth and vasularisation in the human body. The scaffolds also have textural porosity in the mesopore range (10–20 nm). The scaffolds were sintered at 600, 700, 800 and 1000 °C. As sintering temperature was increased to 800 °C the compressive strength increased from 0.34 to 2.26 MPa due to a thickening of the pore walls and a reduction in the textural porosity. The compressive strength is in the range of that of trabecular bone (2–12 MPa). Importantly, the modal interconnected pore diameter (98 μm) was still suitable for tissue engineering applications and bioactivity is maintained. Bioactive glass foam scaffolds sintered at 800 °C for 2 h fulfill the criteria for an ideal scaffold for tissue engineering applications.