Beta-tricalcium phosphate enhanced mechanical and biological properties of 3D-printed polyhydroxyalkanoates scaffold for bone tissue engineering

Polyhydroxyalkanoates (PHA) is a naturally degradable polyester with good biocompatibility. However, several disadvantages including poor bioactivity and mechanical properties limit the biomedical application of PHA. To circumvent these drawbacks, PHA needs to be blended with other materials to improve performance. Beta-tricalcium phosphate (β-TCP) has emerged as one of the most promising bone repair materials due to its good biocompatibility, satisfactory mechanical properties, and excellent bone osteoconductivity. In this study, PHA filled with β-TCP in 0 wt%, 5 wt%, 10 wt%, 20 wt%, and 30 wt% of concentrations were produced using a twin-screw extruder. The extruded 3D filaments made with 20% β-TCP exhibited the maximum mechanical properties to manufacture 3D scaffolds for bone tissue engineering. We then prepared the 3D-printed PHA/β-TCP scaffolds by using the fused deposition modeling (FDM) technique. The compressive strength and the shore hardness of the PHA/20%β-TCP scaffold were 36.7 MPa and 81.1 HD. The produced scaffolds presented compressive strength compatible with natural bone. In addition, the scaffolds with a well-controlled design of pore shape and size provided sufficient space for cellular activity. In vitro studies demonstrated that the addition of β-TCP could significantly improve the proliferation, adhesion, and migration of MC3T3-E1 cells in the PHA/β-TCP scaffold. Moreover, the osteogenesis-related genes expression of the PHA/β-TCP scaffold was enhanced compared to the PHA scaffolds. Therefore, the 3D-printed PHA/β-TCP scaffold represents an effective strategy to promote mechanical and biological properties, showing huge potential for bone tissue engineering applications.