3D printed MXene (Ti2AlN)/polycaprolactone composite scaffolds for in situ maxillofacial bone defect repair

• In situ bone repair scaffolds with different content Ti 2 AlN/polycaprolactone were prepared by FDM 3D printing technology. • Ti 2 AlN/polycaprolactone scaffolds were used to repair the bone defects of rat tibia and rabbit maxillofacial bone. • Scaffold with 5% Ti 2 AlN content showed the best osteogenesis in vitro and bone repair in vivo . • Transcriptome profile revealed the osteogenic signaling pathway involved in Ti 2 AlN. Obtaining a safe and reliable scaffold that can be rapidly fabricated and used for clinical bone defect repair has always been a challenge. In this study, polycaprolactone (PCL) composite scaffolds with various MXene (Ti 2 AlN) contents were prepared using 3D printing technology. The effects of different contents of Ti 2 AlN on the mechanical properties, hydrophilicity, cytocompatibility, and osteogenic differentiation ability were systematically studied and analysed. In vitro experiments showed that scaffolds containing 5% Ti 2 AlN (PCL@5#Ti 2 AlN) obtained the best cell adhesion and proliferation ability and significantly upregulated the alkaline phosphatase (ALP) level. In vivo experiments of tibial defect repair in rats showed that the PCL scaffold containing 5% Ti 2 AlN (PCL@5#Ti 2 AlN) could significantly promote the formation of new bone, and the experimental results of rabbit maxillofacial bone defect repair further proved that the PCL@5#Ti 2 AlN scaffold could effectively promote the repair of bone defects. Transcriptome analysis indicated that Ti 2 AlN may promote osteogenic differentiation by the Wnt/β-catenin signaling pathway and calcium-binding proteins. These findings suggest that Ti 2 AlN/PCL composite scaffolds with improved in situ bone repair ability represent an intelligent strategy for bone defect repair.