Super-assembled niobium-MXene integrated frameworks for accelerated bone repair and osseointegration

Niobium is attracting more and more attention in dental and orthopedic clinical applications. On the one hand, niobium alloy has verified its good biocompatibility, corrosion resistance and mechanical properties; on the other hand, niobium nanomaterials could reduce the osteoclast activation through ROS absorption, which is conducive to bone tissue regeneration. The impressive osteogenesis ability of niobium-based nanomaterials inspired the strategy to load the 2D niobium into bioactive responsive carriers and directly deploy in bone defects to promote bone regeneration efficiently and in situ. Here, a bone cement was constructed through the innovative super-assembled strategy that had integrated the nano-level 2D niobium carbide MXene to the macroscopic 3D GelMA photo-cured frameworks. The super-assembled bone cement can achieve accelerated bone fracture healing and osseointegration in various preclinical mouse models without any detectable toxicity. Mechanistically, 2D Nb₂C bone cement promoted osteoblast activation without altering osteoclast function in vivo. Transcriptomics and chromatin immunoprecipitation revealed that 2D Nb₂C stimulates GATA3-GPNMB signaling to active osteoblasts in mice. In freshly isolated human osteoblasts, 2D Nb₂C stimulated osteoblast activation and calcification. This work proposes a topically effective, non-toxic, low-cost 2D Nb₂C-based bone cement with distinct clinical translational potential in dentistry and orthopedics.