Synthesis of Fe3O4@ICG Nanoparticles for Enhanced Synergistic Therapy Against Biofilm Infections Associated with Dental and Orthopedic Implants

The infections associated with dental and orthopedic implants always result from the biofilm of bacterial colonization, leading to implant failure, prolonged hospitalization, and increased healthcare costs. Iron oxide (Fe 3 O 4 ) nanoparticles and indocyanine green (ICG) are both reported to have good antibacterial properties. However, the anti-biofilm efficiency of either component alone is still unsatisfactory. In this paper, octahedral Fe 3 O 4 nanoparticles (O-Fe 3 O 4 ) were synthesized and integrated with ICG to achieve the best biofilm removal effect, and the optimized ratio between the Fe 3 O 4 and ICG was also investigated. The results showed that ICG inhibited the magnetic properties of Fe 3 O 4 slightly (from 92 emu/g to 76 emu/g); however, it endowed Fe 3 O 4 with significantly improved photothermal, photodynamic, and peroxidase-like activities, achieving excellent antibacterial property (eradicating more than 99% of S. aureus under the combination of H 2 O 2 treatment and laser irradiation). Combined with the good cytocompatibility (cell viability > 80% at a concentration of 250 μg/mL), the synthesized O-Fe 3 O 4 @ICG nanoparticles (especially O-Fe 3 O 4 @ICG-10) have strong application potential for synergistic therapy against biofilm infection associated with dental and orthopedic implants. This study presents a promising nano-antibacterial system for combating resistant biofilm infections, offering insights into the rational design of synergistic nanotherapeutics for clinical applications.