Effects of ZnO/SrO/akermanite incorporation on the microstructure, mechanical properties, and in vitro osteogenic performance of β -tricalcium phosphate scaffolds

Abstract To address the inherent brittleness of β -tricalcium phosphate ( β -TCP) bioceramics, we incorporated ZnO, SrO, or bioactive glass (AK) into a β -TCP matrix. Porous scaffolds were fabricated via digital light processing and sintering. X-ray diffraction confirmed the preservation of the β -TCP phase, and SEM revealed a multiscale porous architecture with uniform macropores (∼400 μm) and submicron surface micropores specifically in the β -TCP/AK composite. This scaffold exhibited the most balanced performance: its compressive strength increased by ∼38% to 9.65 MPa compared to pure β -TCP. During immersion in simulated body fluid, the β -TCP/AK scaffold induced a favorable alkaline pH, exhibited the highest degradation rate (mass loss), and enabled sustained release of bioactive Si 4+ and Mg 2+ ions, which enhanced apatite mineralization. In vitro , all modified scaffolds promoted osteoblast proliferation. Notably, the β -TCP/AK scaffold most significantly stimulated osteogenic differentiation, elevating ALP activity to 2.48 ± 0.184 (vs. 1.87 ± 0.126 for pure β -TCP) and upregulating key osteogenic genes (ALP, OCN, RUNX2). These results demonstrate that AK doping optimally enhances the mechanical strength, biodegradation, ion release, and osteogenic capacity of β -TCP, presenting a highly promising composite for bone tissue engineering.