Instant Visualization and Selective Elimination of Oral S. Mutans

Objectives: Dental caries are mainly caused by the acidic environment produced by bacterial biofilms. S.mutans, a Gram-positive bacteria, is the main pathogenic bacteria for the formation of biofilms in severe childhood caries. At present, clinical modalities are limited to macroscopic plaque staining technology, which can’t evaluate and quantify biofilm with high resolution. Although optical materials have been developed for imaging biofilm, the response time is long, and the Gram-positive bacteria in biofilm cannot be tracked selectively in real time. Additionally, Antibiotics are the mainly used weapons to fight caries biofilms, but the extensive use of antibiotics leads to bacterial resistance. Meanwhile, antibiotics lack selectivity in sterilization, so they kill some beneficial bacteria while killing harmful bacteria, which may damage the healthy oral microecology. Therefore, the effective diagnosis and specific removal of caries biofilm remain challenging.
Methods: Herein, we prepared 4-[Bis(4-methoxyphenyl)amino]benzaldehyde covalently bonded with positively charged methylpyridine to obtain aggregation-induced-emission (AIE) photosensitizer (MeOTpy), which can specifically stain Gram-positive bacteria with negative surface electricity.
Results: MeOTpy emits fluorescence after binding with Gram-positive bacteria and generates reactive oxygen species in high efficiency under white light irradiation. It has significant advantages such as instant imaging, no drug resistance, low cytotoxicity, high temporal and spatial resolution and selective targeting. It realizes the combined application of fluorescence imaging technology and photodynamic therapy (PDT) for dental caries.
Conclusions: Although AIEgens has been widely studied in the field of tumor treatment and anti-bacteria, its application for treating oral diseases is still relatively rare. This work will provide a new method and perspective for the clinical diagnosis and treatment of dental caries and other oral infections in the future.