<scp>PB</scp>/<scp>CeO₂</scp> Nanoparticles Regulating Reactive Oxygen Species for the Control of <scp><i>Enterococcus faecalis</i></scp> Infection in Root Canals

To investigate the antibacterial effect, mechanism, and cytotoxicity of Prussian blue/Cerium dioxide (PB/CeO₂) nanoparticles against Enterococcus faecalis (E. faecalis) and biofilm. PB/CeO₂ nanoparticles were synthesized and characterized. The antibacterial mechanism of nanoparticles was explored through peroxidase (POD) activity assay, hydroxyl radicals (·OH) detection, and measurement of bacterial reactive oxygen species (ROS) and glutathione (GSH)/glutathione disulfide (GSSG) levels. The biocompatibility of PB/CeO₂ was evaluated by Cell Counting Kit-8 (CCK-8) assay and histological examination of the major visceral organs of rats. The antibacterial effect of PB/CeO₂ was assessed using the colony-forming unit (CFU) method. The impact of PB/CeO₂ on E. faecalis biofilm on dentin slices was further observed with CLSM and SEM. ANOVA and t-test were applied for statistical analysis (p < 0.05). PB/CeO₂ demonstrated significant antibacterial activity against E. faecalis, mainly when used with H₂O₂, significantly enhancing its antibacterial effect and effectively disrupting E. faecalis biofilms on dentin slices. PB/CeO₂ nanoparticles catalyzed ROS production, disrupting the antioxidant defense system of E. faecalis cells, damaging bacterial cell membranes, and ultimately causing bacterial death. PB/CeO₂ nanoparticles exhibit good biocompatibility at appropriate concentrations in vivo and in vitro. The novel multifunctional nanocomposite shows great antibacterial effects against E. faecalis and its biofilm, with low cytotoxicity and good biocompatibility, offering a novel disinfection strategy for root canal treatment.