(293f) An Antibiotic-Free Nano-Enabled Approach for the Topical Eradication of Dental Biofilm without Disturbing Microbiota Balance In Vivo Using Carbon Dots

Dental plaques are one of the most prevalent types of biofilm which can lead to dental caries due to the demineralization processes caused by acidogenic bacteria. These bacteria reside inside a protective sheath i.e. extracellular polymeric substances which makes any curative biofilm treatment challenging. Herein, we propose an antibiotic-free strategy to disrupt the biofilm by utilizing nanoparticles designed to function in the acidic environment of these biofilms. Carbon dot nanoparticles were decorated with phosphonium ions to endow them with antibiofilm properties and they were made stimuli-responsive by their entrapment in a pH-sensitive polymer shell. Mechanistic studies on Streptococcus mutans (S. mutans) revealed that the toxicity of these nanoparticles was mediated by their electrostatic interactions with the bacterial membrane, the generation of excess reactive oxygen species (ROS), and subsequent DNA fragmentation. In vitro and Ex vivo studies on mature biofilms revealed more than 90% biofilm inhibition. An in vivo examination in a rat model of dental biofilm further showed that the nanoparticles could effectively suppress the growth of S. mutans. The nanoparticles were biodegradable in artificial saliva after ten days and did not show any adverse effects on the surrounding oral tissues or on internal organs. Importantly, 16S rRNA analysis of the dental microbiota showed that the diversity and richness of bacterial species did not significantly change with nanoparticle treatment. Overall, this study presents a safe and effective, antibiotic-free approach to decrease the S. mutans population and dental biofilm formation without disrupting the ecological balance of the oral cavity.