Engineering a multifunctional PDA-assisted mineralized interface on 3D printed gallium-doped calcium silicate scaffolds for enhanced osteogenesis and angiogenesis

Bioceramic scaffolds are widely used for the repair of bone defects caused by trauma, tumor resection, and osteomyelitis. However, achieving both high mechanical strength and excellent bioactivity in bioceramic scaffolds remains a significant challenge. To overcome this limitation, gallium-doped calcium silicate@polydopamine@calcium phosphate/magnesium (CSi-Ga@PDA@CaP/Mg) composite scaffolds were fabricated via projection-based 3D printing technique. The effects of dopamine deposition time and concentration on PDA coating formation were systematically investigated, and the optimal condition (24 h, 2 mg/mL) was identified. Under this condition, uniform CaP/Mg coatings were successfully deposited without compromising the porous architecture. The composite scaffolds exhibited high compressive strength (∼48 MPa) and elastic modulus (∼504 MPa), while retaining compressive strength above 24 MPa and elastic modulus above 255 MPa after immersion in Tris buffer solution for 3 weeks. In addition, the scaffold exhibited synergistic multi-ion release and significantly enhanced endothelial cell angiogenic activity, including vascular network formation, CD31 expression, and angiogenesis-related gene expression. Moreover, the scaffold significantly promoted the adhesion, proliferation, and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Overall, the CSi-Ga@PDA@CaP/Mg scaffold achieved a desirable combination of high mechanical strength, pro-angiogenic capability, and osteogenic activity, suggesting its potential as a multifunctional bioceramic scaffold for bone regeneration.