Bioheterojunctions Prevent Tooth Caries via Cascade Antibacterial Strategy

Tooth caries is a prevalent chronic oral disease with microorganisms as the initiating factor and carbohydrates as the key environmental factor. Clinical antimicrobial therapies rely mainly on broad-spectrum antibiotics, which usually increase the risk of bacterial resistance. Recently, phototherapy has shown powerful antibacterial effects, although it cannot effectively eliminate cariogenic microenvironments and the antibacterial effect is not sustained after the light is removed. Here, we developed novel bioheterojunctions (bio-HJs) comprising MXene/Ag₃PO₄ (MX/AgP) and glucose oxidase (GOx), denoted MX/AgP-GOx, aiming at both the chemical and biological components of dental plaque biofilm. The bio-HJs decomposed the glucose rich in the cariogenic environment through GOx while providing abundant H₂O₂ for subsequent Fenton reaction. Under near-infrared (NIR) light, the bio-HJs produced hyperthermia and generated large amounts of reactive oxygen species based on the above H₂O₂, exerting powerful phototherapy properties (log reduction: 1.45 log 10 CFU/mL). It is worth noting that MX/AgP-GOx still exerted antibacterial effects in the dark via Ag⁺ bactericidal effects, Ag⁰ NPs catalytic activity, and GOx-mediated glucose depletion (log reduction: 0.39 log 10 CFU/mL), ensuring a sustained anticaries effect after the removal of NIR light. In addition, the rat caries model revealed that MX/AgP-GOx significantly reduced enamel mineral loss and had good biocompatibility. This study constructed efficacy-cascade bio-HJs targeting the sugar-rich cariogenic microenvironment, which promotes subsequent photodynamic therapy and combines photothermal and metal ion synergistic antibacterial means to continuously and effectively eliminate biofilm and prevent the occurrence and development of tooth caries.