Nanocatalysts promote Streptococcus mutans biofilm matrix degradation and enhance bacterial killing to suppress dental caries in vivo

Abstract

Dental biofilms (known as plaque) are notoriously difficult to remove or treat because the bacteria can be enmeshed in a protective extracellular matrix. It can also create highly acidic microenvironments that cause acid-dissolution of enamel-apatite on teeth, leading to the onset of dental caries. Current antimicrobial agents are incapable of disrupting the matrix and thereby fail to efficiently kill the microbes within plaque-biofilms. Here, we report a novel strategy to control plaque-biofilms using catalytic nanoparticles (CAT-NP) with peroxidase-like activity that trigger extracellular matrix degradation and cause bacterial death within acidic niches of caries-causing biofilm. CAT-NP containing biocompatible Fe3O4 were developed to catalyze H2O2 to generate free-radicals in situ that simultaneously degrade the biofilm matrix and rapidly kill the embedded bacteria with exceptional efficacy (>5-log reduction of cell-viability). Moreover, it displays an additional property of reducing apatite demineralization in acidic conditions. Using 1-min topical daily treatments akin to a clinical situation, we demonstrate that CAT-NP in combination with H2O2 effectively suppress the onset and severity of dental caries while sparing normal tissues in vivo. Our results reveal the potential to exploit nanocatalysts with enzyme-like activity as a potent alternative approach for treatment of a prevalent biofilm-associated oral disease.

Keywords: Antibacterial; Biofilms; Catalysis; Dental caries; Extracellular matrix; Iron oxide; Nanoparticles.