Fabrication of 3D-printed Ca2Sr(PO4)2-based composite ceramic scaffolds as potential bone regenerative biomaterials

Strontium is a potent osteo-stimulative element with a wide safe dosage range. In this work, calcium-strontium phosphate (Ca2Sr(PO4)(2); abbreviation: CSP) was synthesized, and 3D-printed CSP-based composite (CSP-T) ceramic scaffolds were prepared by introduction of beta-tricalcium phosphate (TCP). When sintering the CSP-T ceramic scaffolds, no new phase was produced, but the strontium from CSP was substituted for calcium in TCP; the TCP additives promoted densification of scaffold filaments, resulting in lower porosity of the CSP-T ceramic scaffolds. The porosity (25.6%-77.1 %) and compressive strength (1.5-44.5 MPa) of CSP-T ceramic scaffolds could be adjusted by altering the amount of TCP additives and the sintering temperature. The CSP-T ceramic scaffolds gradually released ions of calcium, phosphorus and strontium, which were in favor of cell growth and osteogenic differentiation. The CSP-T ceramic scaffolds modified by 25 wt% TCP possessed the greatest performances on enhancing mechanical strength and cellular response, which let them serve as promising bone grafts to treat various sites of bone defects.