Two‐Dimensional‐Germanium Phosphide‐Reinforced Conductive and Biodegradable Hydrogel Scaffolds Enhance Spinal Cord Injury Repair

Abstract Developing biodegradable conductive hydrogels is of great importance for the repair of electroactive tissues, such as myocardium, skeletal muscle, and nerves. However, conventional conductive phase incorporation in composite hydrogels, such as polypyrrole, polyaniline, carbon nanotubes, graphene, and gold nanowires, which are non‐degradable materials, will exist in the body as foreign matter. Herein, an injectable hydrogel based on the integration of conductive and biodegradable germanium phosphide (GeP) nanosheets into an adhesive hyaluronic acid‐graft‐dopamine (HA‐DA) hydrogel matrix is explored, and the successful application of this biohybrid hydrogel in spinal cord injury (SCI) repair is demonstrated. The incorporation of polydopamine (PDA)‐modified GeP nanosheets (GeP@PDA) into HA‐DA hydrogel matrix significantly improves the conductivity of HA‐DA/GeP@PDA hydrogels. The conductive HA‐DA/GeP@PDA hydrogels can accelerate the differentiation of neural stem cells (NSC) into neurons in vitro. In a rat SCI complete transection model, the in vivo implanted HA‐DA/GeP@PDA hydrogel is found to improve the recovery of locomotor function significantly. The immunohistofluorescence investigation suggests that the HA‐DA/GeP@PDA hydrogels promote immune regulation, endogenous angiogenesis, and endogenous NSC neurogenesis in the lesion area. The strategy of integrating conductive and biodegradable GeP nanomaterials into an injectable hydrogel provides new insight into designing advanced biomaterials for SCI repair.