Structural and material double mechanical enhancement of HAp scaffolds promote bone defect regeneration

Critical bone defects caused by trauma, bone tumors, and infections are still challenges in clinical surgery. Digital light processing printing of hydroxyapatite (HAp) scaffolds can fabricate high-resolution personalized bone repair scaffolds. However, creating load-bearing bone regeneration HAp scaffolds with satisfactory mechanical property remain challenging. This study investigated the enhancement of the HAp scaffold mechanical properties from both structural and material perspectives. Structurally, the diamond structure model was optimized to Triply Periodic Minimal Surface structures, increasing the compressive strength of scaffolds from 2.2 to 7.2 MPa. Material-wise, ZnO was incorporated as second-phase particle, improved the compressive strength of HAp scaffolds from 7.2 to 13.7 MPa. Additionally, the incorporation of zinc ions enhanced the bioactivity of the HAp scaffolds. Animal mechanical testing revealed that the enhanced scaffolds effectively supported load-bearing. The HAp/ZnO-TPMS scaffolds exhibited excellent mechanical properties and promoted cellular osteogenic differentiation, showing potential for clinical development and application.