Biosilicate® scaffolds produced by 3D-printing and direct foaming using preceramic polymers

Monolithic and powdered Biosilicate®, produced by conventional glass-ceramic technology, have been widely recognized as excellent materials for bone tissue engineering applications. In the current research, we focus on an alternative processing route for this material, consisting of the thermal treatment of silicone polymers containing micro-sized oxide fillers, which offers a unique integration between materials synthesis and shaping. In particular, the new method allows obtaining highly porous Biosilicate® glass-ceramics, in the form of 3D printed scaffolds and foams. 3D scaffolds were successfully fabricated by direct writing using an ink based on a silicone polymer and active inorganic fillers, followed by firing in air at 1000°C. The products showed regular geometries, large open porosity (~60 vol%) and still high compressive strength (~7 MPa). Open-cellular foams with porosity up to ∼80 vol% were also prepared from liquid silicones mixed with several fillers, including hydrated sodium phosphate. This specific filler acted both as a foaming agent, because of the gas release by dehydration occurring at low temperature, and as a provider of liquid phase upon firing in air, again at 1000°C.