Enhanced mechanical properties and biological responses of SLA 3D printed biphasic calcium phosphate bioceramics by doping bioactive metal elements

Favorable mechanical properties and outstanding bioactivity are necessary for bioceramics used for bone defect repair. The doping of Mg²⁺ and Fe³⁺ can improve the mechanical properties and bone regeneration capacity of calcium phosphate ceramics. In this study, magnesia oxide (MgO), ferric oxide (Fe₂O₃), and iron (Fe) powders are chosen as dopants to enhance biphasic calcium phosphate (BCP) bioceramics, and the MgO-BCP, Fe₂O₃-BCP, Fe-BCP bioceramics are prepared by stereolithography (SLA) for the first time. The effects of these dopants on the curing behavior of bioceramic slurries, mechanical properties, biodegradation, and cytocompatibility of BCP bioceramics are studied. The addition of 1 wt% Fe well enhances the flexural strength of BCP from 91.61 MPa to 122.60 MPa sintered at 1250 °C. The addition of 1 wt% MgO effectively promotes the biodegradation of BCP in simulated body solution (SBF), and enhances the proliferation of mouse pre-osteoblast (MC3T3-E1) cells in vitro. In addition, Fe powder is more suitable as a dopant for SLA 3D printed BCP than Fe₂O₃ powder, and all the performances of Fe-BCP are better than those of Fe₂O₃-BCP. The less microstructure defects and slower Fe³⁺ release rate make Fe-BCP have higher flexural strength and less cytotoxic compared with Fe₂O₃-BCP. This novel way exhibits beneficial effects of bioactive metal elements on mechanical properties and bioactivity, and indicates SLA 3D printed BCP bioceramic doped with MgO, Fe can be promising candidates for bone defect repair.