An injectable phosphocreatine-grafted gelatin hydrogel incorporating berberine-loaded copper-carbon dot nanozymes for osteoporotic bone regeneration

Osteoporotic bone defects represent a multifactorial clinical challenge due to impaired osteogenesis, insufficient angiogenesis, hyperactive osteoclast activity, and high infection risk. To address these limitations, we developed an injectable phosphocreatine-grafted gelatin hydrogel (BCG) incorporating berberine-loaded copper‑carbon dot nanozymes (BBR-CuCDs). BBR-CuCDs were synthesized via a one-step hydrothermal method, enabling simultaneous drug loading and catalytic activity, while dual enzymatic and Cu 2+ coordination crosslinking endowed the hydrogel with enhanced mechanical integrity, stability, and sustained release of therapeutic payloads. In vitro, BCG hydrogels significantly promoted BMSC proliferation, adhesion, migration, and osteogenic differentiation, while enhancing HUVEC migration, tube formation, and angiogenic marker expression. The hydrogels also suppressed RANKL-induced osteoclastogenesis and exhibited strong antibacterial effects against both Staphylococcus aureus and Escherichia coli . In vivo, BCG (1.0 mg/mL) hydrogel markedly accelerated bone regeneration and neovascularization in an ovariectomized rat calvarial defect model, as demonstrated by micro-CT and histological analyses, accompanied by elevated expression of COL1A1, BMP2, RUNX2, and CD31. Importantly, transcriptomic profiling revealed that BCG hydrogel activated PI3K-Akt, Wnt/β-catenin, and HIF-1 signaling pathways, highlighting a coordinated mechanism of osteogenesis-angiogenesis coupling and immune modulation. Collectively, this multifunctional hydrogel integrates osteoinductive, proangiogenic, anti-osteoclastic, and antibacterial activities, and demonstrates excellent biosafety, offering a robust and translationally promising platform for osteoporotic bone defect repair.