Direct ink writing of wollastonite-diopside glass-ceramic scaffolds from a silicone resin and engineered fillers

Wollastonite-diopside scaffolds have been successfully developed by direct ink writing of an ink made of silicone polymer and inorganic fillers. The main reason for using a silicone in the ink formulation consisted in its double effect, in controlling the ink rheology and in developing of wollastonite and diopside crystalline phases upon heat treatment. The obtained 3D wollastonite-diopside scaffolds featured regular geometries, and a high compressive strength (3.9-4.9 MPa) when considering the large amount of porosity (68-76 vol.%). A glass with the same oxide composition as the silicone-based ink and crystallizing into wollastonite and diopside, was produced and used as additional filler. This addition enabled the fabrication of even stronger 3D printed scaffolds (∼8 MPa for a porosity of 67 vol%), owing to the enhanced viscous flow upon firing which reduced the micro-cracks in the scaffold struts generated by the preceramic polymer decomposition. The obtained highly porous wollastonite-diopside glass-ceramic scaffolds are suitable candidates for bone tissue engineering.