Dual‐Functional Injectable Photothermal Nanohydrogel Promotes Anti‐Inflammation and Bone Regeneration in Distraction Osteogenesis

Abstract Large bone defects regularly result in prolonged pain and functional impairment in patients, providing a considerable challenge in medical treatment. Current research in biomaterials for bone defect repair is increasingly centered on integrating osteogenic performance with antibacterial properties inside nanomaterials. In this study, a biomimetic hydrogel with an osteogenic microenvironment is developed primarily based on 2D black phosphorus (BP) nanosheets incorporated into poly‐amino acid calcium alginate. Compared to methods using black phosphorus alone, this BP@L‐lysine‐Polyglutamic acid calcium alginate gel hydrogel (BP@CALG) exhibits reduced cytotoxicity, enhanced mechanical stability, and superior antibacterial properties, thereby synergistically augmenting its osteogenic potential and antibacterial efficacy. Through near‐infrared (NIR) irradiation, the hydrogel's osteoinductive and antibacterial abilities are further optimized by means of controllable photothermal activation. Notably, BP@CALG demonstrates immunomodulatory capabilities that facilitate osteogenesis through macrophage polarization. By steering M0 macrophages toward the regenerative M2 phenotype and simultaneously inhibiting pro‐inflammatory M1 differentiation, the scaffold effectively controls excessive inflammation. This dual mechanism promotes bone regeneration both directly through osteogenic signaling pathways and indirectly via immune microenvironment regulation.