Functionalized 3D-Printed PCL/β-TCP Scaffolds with ZnO for Enhanced Bone Healing

Alveolar ridge deficiency remains a significant clinical challenge in dental implantology, often necessitating bone augmentation procedures. While autogenous bone grafting is considered the gold standard, its limitations, including donor site complications and limited availability, have prompted the development of alternative bone graft materials. In this study, we fabricated a novel polycaprolactone (PCL)/β-tricalcium phosphate (β-TCP)@zinc oxide (ZnO) composite scaffold via direct ink writing (DIW) three-dimensional (3D) printing. The scaffold integrates a biomimetic porous architecture with a controlled ion-release strategy to enhance osteogenic performance. The characterization of the material confirmed excellent chemical stability, hydrophilicity, and tunable degradation behavior. The incorporation of ZnO facilitated the sustained release of bioactive ions (Ca²⁺, PO₄ ^3-, and Zn²⁺), significantly improving the scaffold's bioactivity. In vitro assessments revealed that the scaffold with 2% ZnO (PTZ-2) exhibited optimal cytocompatibility and osteogenic differentiation capacity, promoting alkaline phosphatase activity and mineralized nodule formation in MC3T3-E1 cells. In a rat cranial defect model, the PTZ-2 scaffold achieved approximately 95% new bone area after 12 weeks. Histological analysis further confirmed the presence of continuous, highly mineralized bone matrix with excellent osseointegration capability. These findings collectively indicate that the 3D-printed PCL/β-TCP@ZnO composite scaffold has great potential for clinical translation in bone defect regeneration.