Additive manufacturing of 3D porous alkali-free bioactive glass scaffolds for healthcare applications

This work deals with the fabrication by robocasting of 3D porous scaffolds of an alkali-free bioactive glass composition, FastOs®BG, belonging to the diopside (CaMgSi2O6)–fluorapatite (Ca5(PO4)3F)–tricalcium phosphate (Ca3(PO4)2) system. A glass frit prepared by melt quenching was grinded by dry and wet milling up to getting a suitable combination of particle sizes. The milled frit was then dispersed in aqueous media with the addition of a polycarbonate dispersant, hydroxypropyl methylcellulose (HPMC) as binder and Aristoflex® TAC as gelation agent. The effects of the type and amounts of the processing additives and particle size distribution on the rheological properties of the extrudable pastes were investigated. Printable inks containing 47 vol.% solids with rheological properties tuned to meet the stringent requirements of robocasting technique were obtained. Scaffolds with totally interconnected 3D pore networks and different pore sizes (200, 300 and 500 µm) could be easily fabricated and sintered. The excellent processing and sintering ability resulted in compressive strength values comparable to that of cancellous bone essential for 3D porous scaffolds intended for bone regeneration and tissue engineering applications.