Compositionally Optimized Bone Scaffolds Based on Carbonate Apatite and Silver Phosphate for Osteogenesis, Scaffold Resorption, and Photoactivated Antibacterial Activity

Antimicrobial resistance (AMR) is a growing global health concern, especially in the management of bone and joint infections. A bioresorbable scaffold comprising carbonate apatite and 0.4 wt % silver phosphate (Ag₃PO₄) (designated as CASP) was developed in this study to achieve simultaneous osteogenesis, scaffold resorption, and photoactivated antibacterial activity. The CASP scaffold exhibits intrinsic antibacterial activity within 1 h via Ag⁺ ion release, which is further enhanced under visible light irradiation through the generation of reactive oxygen species generation. In vitro studies demonstrate that CASP scaffolds effectively suppress the growth of methicillin-resistant <i>Staphylococcus aureus</i> without compromising osteoblast viability, proliferation, differentiation, and calcification. In vivo implantation in rabbit femoral defects indicates that CASP scaffolds support robust bone regeneration and gradual scaffold resorption comparable to those of scaffolds without Ag₃PO₄ while maintaining long-term antibacterial activity for at least 4 weeks postimplantation. Transient inflammatory responses observed early after implantation are detoxified over time, potentially through the in vivo sulfidation of released silver ions. The findings of this study highlight the potential of CASP scaffolds as promising candidates for nonantibiotic infection control and bone tissue regeneration via visible light-driven photocatalytic therapy, offering an effective strategy to combat AMR in orthopedic applications.