Engineered with tannic acid-magnesium metal-phenolic frameworks: A multifunctional 3D-printed PCL/TCP scaffold for...

Critical-sized bone defects, typically resulting from trauma, infection, or tumor resection, pose a substantial clinical challenge. Traditional bone grafting methods, including autografts and allografts, face constraints due to donor scarcity, surgical morbidity, immune rejection, and infection risks. Bone tissue engineering has recently emerged as a promising alternative for managing complex bone defects. Among these strategies, 3D printing facilitates the creation of patient-tailored scaffolds with customized mechanical properties, yet the integration of multifunctional attributes like osteogenesis, antibacterial activity, and angiogenesis, remains challenging. In this study, we developed polycaprolactone/β-tricalcium phosphate (PCL/TCP) composite scaffolds using fused deposition modeling, followed by surface modification with a tannic acid/magnesium ion coating (PCL/TCP@TA/Mg²⁺). Both in vitro and in vivo assessments revealed superior biocompatibility, enhanced osteogenic gene and protein expression, increased alkaline phosphatase activity, and accelerated matrix mineralization. The scaffolds also exhibited strong antibacterial activity against Staphylococcus aureus and Escherichia coli, and promoted vascular endothelial growth factor expression and tube formation. Transcriptomic analysis indicated that these effects were associated with AMPK/HIF-1α pathway activation and oxidative stress reduction. In a rat calvarial defect model, PCL/TCP@TA/Mg²⁺ scaffolds significantly enhanced new bone and collagen formation. These findings validate the development of a multifunctional 3D-printed scaffold with synergistic osteogenic, antibacterial, angiogenic, and antioxidative properties, presenting a promising strategy for complex bone defect repair.