Abstract: The high porosity and interconnectivity of scaffolds are critical for nutrient transmission in bone tissue engineering but usually lead to poor mechanical properties. Herein, a novel method that combines acid etching (AE) with selective laser sintering (SLS) and reaction bonding (RB) of Al particles is proposed to realize highly improved porosity, interconnectivity, mechanical strength, and in vitro bioactivity in 3D Al₂O₃ scaffolds. By controlling the oxidation and etching behaviors of Al particles, a tunable hollow spherical feature can be obtained, which brings about the distinction in compressive response and fracture path. The prevention of microcrack propagation on the in situ formed hollow spheres results in unique near elastic buckling rather than traditional brittle fracture, allowing an unparalleled compressive strength of 3.72 ± 0.17 MPa at a high porosity of 87.7% ± 0.4% and pore interconnectivity of 94.7% ± 0.4%. Furthermore, scaffolds with an optimized pore structure and superhydrophilic surface show excellent cell proliferation and adhesion properties. Our findings offer a promising strategy for the coexistence of outstanding mechanical and biological properties, with great potential for tissue engineering applications.

Key words: Ceramic scaffolds, Selective laser sintering, Acid etching, Hollow spherical feature, Mechanical strength, In vitro bioactivity