Peroxidase-mimicking chitosan/dextran-coated cobalt ferrite-graphene oxide nanozyme enhances hydrogen peroxide-mediated killing of cariogenic pathogens in dental biofilm models.

Dental caries is a chronic, multifactorial and biofilm-mediated disease driven by complex microbial interactions within the oral cavity. The causative biofilm is particularly challenging to eliminate due to the protective extracellular matrix that shelters the embedded microorganisms and promotes retention of acidic metabolites, leading to enamel demineralization. Conventional antimicrobial agents are often ineffective in disrupting this matrix and fail to eradicate microbes within biofilms. In this study, we report the synthesis of a novel dextran and chitosan- decorated cobalt ferrite-grafted graphene oxide (CoFe₂O₄/GO@Dex-CS) nanozyme with high peroxidase-like activity as an innovative strategy to control dental biofilms. The nanozyme was synthesized via a facile sono-chemical co-precipitation and coating method. Comprehensive characterization via XRD, FTIR, DLS, TEM, SEM and EDX confirms the nanozyme’s structural integrity and successful functionalization with biocompatible dextran and chitosan, enhancing targeted biofilm penetration and stability. This nanozyme catalyzes hydrogen peroxide to generate reactive oxygen species in situ, resulting in significant reduction in the number of viable bacteria in oral model biofilms. In a monospecies Streptococcus mutans biofilm, the CoFe₂O₄/GO@Dex-CS nanozyme in combination with H₂O₂ exhibited a strong antibiofilm effect, resulting in a reduction of viable S. mutans cells by more than 3-log compared to the untreated control. In a supragingival plaque model biofilm comprising six species a > 2-log reduction in viable S. mutans was observed. Notably, in the same model, the treatment also resulted in a > 3-log reduction of the number of viable Fusebacterium nucleatum and Veillonella dispar as well as in a reduction in the number of viable Actinomyces naeslundii. The biocompatibility of the nanozyme components and its potent catalytic activity highlight its potential for incorporation into mouthwashes or toothpastes to effectively manage dental plaque and prevent caries development. Our findings demonstrate that nanozyme-based catalytic therapeutics offer a promising alternative strategy for the treatment and prevention of biofilm-associated oral diseases.