Function-adaptive clustered nanoparticles reverse Streptococcus mutans dental biofilm and maintain microbiota balance.

Dental plaques are biofilms that cause dental caries by demineralization with acidogenic bacteria. These bacteria reside inside a protective sheath which makes any curative treatment challenging. We propose an antibiotic-free strategy to disrupt the biofilm by engineered clustered carbon dot nanoparticles that function in the acidic environment of the biofilms. In vitro and ex vivo studies on the mature biofilms of Streptococcus mutans revealed >90% biofilm inhibition associated with the contact-mediated interaction of nanoparticles with the bacterial membrane, excessive reactive oxygen species generation, and DNA fragmentation. An in vivo examination showed that these nanoparticles could effectively suppress the growth of S. mutans. Importantly, 16S rRNA analysis of the dental microbiota showed that the diversity and richness of bacterial species did not substantially change with nanoparticle treatment. Overall, this study presents a safe and effective approach to decrease the dental biofilm formation without disrupting the ecological balance of the oral cavity.

Dual purpose hafnium oxide nanoparticles offer imaging Streptococcus mutans dental biofilm and fight it In vivo via a drug free approach.

The removal of tenacious dental plaque is of paramount importance; however, early diagnosis can be a challenging task in dental clinics due to the limitations of current approaches, specifically X-ray-based techniques. We have approached this problem by integrating antibacterial properties and X-ray contrast enhancement in a single probe specific to colonies of Streptococcus mutans as the most predominant and carious oral bacteria. We report the synthesis of an inherently therapeutic polymeric silane conjugated hafnium oxide nanoparticles (Hf PS NPs). Using a high-affinity pathogen-selective peptide, the concept of molecularly targeted X-ray imaging of cariogenic pathogen S. mutans was demonstrated. Ex vivo studies using extracted human tooth demonstrated striking X-ray attenuation of NPs vs. tooth. Additionally, Hf PS NPs exhibited significant bactericidal properties against cariogenic pathogen. Electron microscopy revealed that the antibacterial activity occurred via a 'latch and kill' mechanism. Mechanistic studies determined that these NPs fragmented bacterial DNA components to exert their antimicrobial effect. Importantly, Hf PS NPs effectively inhibited the growth of a mature biofilm on an ex vivo human tooth model. Finally, the NPs were applied to the rodent model of dental biofilm. Topical administration of the Hf PS NPs for 8 days (1X daily) could effectively attenuate the S. mutans biofilm challenge. This report is the first of its kind to demonstrate that HfO2-based NPs can be used for simultaneous diagnosis and antibacterial treatment without requiring an additional drug.