Nano Au@Cu2-xS with near-infrared photothermal and peroxidase catalytic activities redefines efficient antibiofilm-oriented root canal therapy

Killing harmful bacteria in biofilms is a major challenge for current root canal therapy. Although traditional chemical disinfectants have a good bactericidal effect on plankton, they have little efficiency for the removal and sterilization of bacterial biofilms, and even lead to the emergence of bacterial resistance and high toxic side effects. Herein, we propose for the first time biosafe nanocomposites that integrate photothermal and peroxidase-like catalytic activity for efficient removal and killing of bacterial biofilms in root canals. The integration of gold (core) and copper (Ⅰ, Ⅱ) sulfide (shell) shows excellent catalytic effect, which can catalyze the decomposition of hydrogen peroxide at biosafe concentrations to hydroxyl radicals for efficient removal of biofilms. Moreover, studies on the mechanism of antibiofilm showed that the nanocomposites ([email protected]2-xS) have significant degradation effects on proteins and polysaccharides-the main components of biofilm. The in vitro results indicated that the synergism of free radical and heat shows higher sterilization rate against both gram-positive Enterococcus faecalis and gram-negative Fusobacterium nucleus, compared with free radical and heat treatment alone. More importantly, the bactericidal results on isolated dental slices and in root canal models and beagle dog demonstrated the [email protected]2-xS is highly effective in inactivating the bacteria in biofilms. Hence this safe and synergistic antimicrobial system has great potential in antibiofilm-oriented root canal therapy.