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

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. XRD 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 Si⁴⁺ and Mg²⁺ 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.