Preparation and properties of an injectable bone repair material β-tricalcium phosphate/collagen

The injectable artificial bone material was designed to fill complex and irregular bone defects, reduce surgical trauma, and meet higher clinical translation demands. An injectable β-tricalcium phosphate/collagen (β-TCP/COL) composite was prepared by blending β-TCP bioceramic microspheres, which have osteogenic properties, with collagen (COL), plays a crucial role in osteogenic differentiation signaling. The morphology and structure of the material were characterized, and the effects of collagen concentration (10, 20, 30 mg·mL⁻¹), β-TCP particle size (10—63 μm, 63—100 μm), and β-TCP∶COL mass ratio (1∶1, 2∶1) on the physicochemical and biological properties of the composite were evaluated. The β-TCP/COL specifications with strong injectability and osteogenic performance were selected. In the β-TCP/COL composite, collagen fibers encapsulate the β-TCP, preserving both the ceramic and collagen functional structures. High collagen concentration provides the ability to suspend β-TCP; As the microsphere content or size increases, the injection force becomes greater; Smaller particle size and higher content in the β-TCP composite result in more suitable pH, degradation, and biological properties. Through screening, the β-TCP/COL composite with a collagen concentration of 30 mg·mL⁻¹, β-TCP particle size of 10—63 μm, and a mass ratio of β-TCP∶COL of 2∶1 does not produce particle sedimentation. It exhibits an injection force of (30.05±6.27) N, a pH value of 6.24, and a cumulative ion release concentration of 709 mg·L⁻¹ over 10 days of maximum degradation. This composite shows no cytotoxicity, a cell adhesion rate of 46.5%, and significantly superior cell proliferation and osteogenic differentiation compared to other experimental groups, demonstrating excellent comprehensive performance.