Multifunctional injectable BLGFs/ODEX/COL hydrogel With sustained localized phage release for concurrent antimicrobial activity and bone tissue regeneration

Bone tissue has an inherent capacity for regeneration; however, this process is significantly impaired when the bone defects is large and infected by bacteria, particularly with multidrug-resistant strains. In this study, an injectable β-lactoglobulin fibrils/oxidized dextran/collagen (BLGFs/ODEX/COL) hydrogel biomaterial embedded with Acinetobacter baumannii bacteriophages was developed and evaluated for treating infected partial-thickness cortical tibia bone defects in rat models. The bacteriophage was successfully isolated from hospital sewage, amplified, purified, and morphologically confirmed using TEM. The SEM results showed that the hydrogel exhibited a highly porous and interconnected structure with pore sizes exceeding 50 µm, conducive for cell infiltration and tissue regeneration. ATR-FTIR analysis verified the chemical interactions amongst BLGFs, ODEX, and COL, confirming successful hydrogel formation. In vivo results demonstrated that bone defects treated with the phage-loaded hydrogel showed significantly accelerated bone regeneration by day 21 compared to antibiotic-treated and phage-only groups. Micro-CT analysis revealed superior outcomes in the hydrogel group, including higher tissue volume (above 4000 mm³), increased percent bone volume (above 2.4%), and greater bone surface density (above 0.1/mm), indicating enhanced osteogenesis and bone remodeling despite infection. The incorporation of bacteriophages into the BLGFs/ODEX/COL hydrogel provides a synergistic therapeutic strategy by combining localized antimicrobial activity with structural and biological support, thereby promoting improved healing of infected bone defects.