Biomimetic design and fabrication of hydroxyapatite bone scaffolds with controllable interconnected pores via modified direct foaming method

In this study, a modified direct foaming method is proposed to fabricate self-setting inorganic foams that form porous hydroxyapatite (HA) scaffolds with interconnected pore structures. These scaffolds are designed to meet the specifications for personalized bone repair, such as homogeneous pores and desirable mechanical properties. Particle-stabilized HA foams are utilized, allowing the scaffold material to be shaped and consolidated at room temperature, effectively bypassing the challenging drying and sintering steps. By controlling the amphiphile and solid contents and their ratios, the pore morphology and size distribution within the scaffolds are precisely managed. The process involves a water-consuming cement hydration reaction, which prevents macroscopic shrinkage, cracks, and cavity formation across the scaffolds. The resulting scaffolds demonstrate 75% porosity with a hierarchical pore structure, featuring interconnected pores of approximately 100 μm in diameter surrounded by microporous walls. The scaffolds support compressive loads between 50 and 100 N and maintain cell viability rates above 70% in cytotoxicity tests, indicating their biocompatibility. This template-free, replica-free, and pore promoter-free approach offers a promising method for fabricating interconnected porous HA scaffolds for bone tissue engineering applications, including controlled drug release within the scaffold.