MXene and Near-Infrared Carbon Dots Co-Encapsulated Hydrogel Facilitates Infected Bone Defect Reconstruction

Inadequate bone differentiation and intractable biofilm formation due to stubborn bacterial infection complicate infected bone defect repair. Adding harmful antibiotics into scaffolds not only promotes multidrug-resistant bacteria but also decreases bone repair effect. Furthermore, dynamic monitor of scaffolds' degradation is crucial for achieving visualized bone defect repair, however, currently reported biomaterials do not have imaging tracing capabilities. On this basis, this work develops a scaffold material with triple functionality for visualized therapy of infected bone defects: antibacterial, osteogenesis, and near-infrared (NIR) imaging capabilities. Single-layer Ti₃C₂T_x with broad-spectrumantibacterial activity and negatively charged carbon dots (CDs) with osteogenic activity are synthesized for infected bone defect repair. To validate antibacterial and osteogenic activities in vivo, 3D injectable hydrogels encapsulated with Ti₃C₂T_x and CDs (CD/Ti₃C₂T_x/GelMA) are constructed. NIR imaging is used to monitor the degradation process of CD/Ti₃C₂T_x/GelMA hydrogels in infected bone defect models, which indicated that CDs are completely released from hydrogels in about 30 days. Owing to the continuous release of Ti₃C₂T_x and CDs, the obtained CD/Ti₃C₂T_x/GelMA hydrogels can efficiently promote the repair of infected bone defects within 60 days. These findings develop a new biomaterial with great performance for visualized antibacterial and osteogenic therapy of infected bone defects.