Bacterial biofilm microenvironment responsive copper-doped zinc peroxide nanocomposites for enhancing chemodynamic therapy

Dental plaque, a kind of natural biofilm, has attracted much attention because of its role in caries and periodontal disease. The pathogenicity of the dominant bacterial species of S. mutans is based on the formation of extracellular polysaccharides (EPS) and its survival in acidic environments. In addition, the formed plaque biofilm has the characteristics of water insolubility, retention, and low membrane permeability. This is why there are no effective antibiotics or   other ways to treat dental caries. Chemodynamic therapy (CDT) is an ideal therapeutic modality with biofilm microenvironment as stimulus. In this paper, a unique nanocomposite, ZnO 2 -Cu@RB NPs, has been prepared which is composed of copper-doped zinc peroxide nanoparticles (ZnO 2 -Cu NPs) and antibacterial agent Rose Bengal (RB). It can quickly (<10 min) and efficiently kill S. mutans (greater than 8.0 log 10 CFU mL −1 ) in acidic biofilm via the in situ enhanced CDT, and significantly reduce the demineralization of apatite. ZnO 2 -Cu@RB NPs can also weaken the acid production of S. mutans and inhibit the formation of EPS. More significantly, excellent therapeutic efficacy against S. mutans in the rat model was observed. Our findings reveal the great potential of metal peroxide nanoparticles as a new strategy for combating biofilm-related diseases.