Qiaomu Huang,Shilei Wang,Yujun Sun,Cheng Shi,Hao Yang,Zhong Lu
Objective Streptococcus mutans ( S. mutans ), the main pathogen of dental caries, could be well killed by Ag/ZnO nanocomposite. However, effects on virulence factors remain to be elucidated. This study investigated effects of Ag/ZnO at sub-minimum inhibitory concentrations (sub-MICs) on virulence factors of S. mutans and related genes expressions. Design Effects of Ag/ZnO on the growth of S. mutans was investigated by growth curves and MTT staining method. The influence of Ag/ZnO at sub-MICs on biofilm formation was measured by the crystal violet staining method and observed by a scanning electron microscopy. Adherence, cell-surface hydrophobicity, acidogenicity and extracellular polysaccharides (EPS) of S. mutans after treatment by Ag/ZnO at sub-MICs were also investigated. Virulence factors related genes expressions after treated by Ag/ZnO at 1/2 MIC was conducted by the quantitative real-time PCR (qRT-PCR) method. Results Sub-MICs of Ag/ZnO exhibited a dose-dependent inhibition on the virulence factors of S. mutans . Specially, Ag/ZnO at 1/2 MIC decreased 69.00 % biofilm formation, 31.78 % sucrose-independent and 48.08 % sucrose-dependent adherence, 69.44 % cell-surface hydrophobicity and 72.45 % water-soluble and 90.60 % water-insoluble EPS. Furthermore, the expression of virulence factors related genes was significantly suppressed by Ag/ZnO at 1/2 MIC. Conclusions Ag/ZnO at sub-MICs inhibited multiple virulence factors of S. mutans through downregulating the related genes. Ag/ZnO nanocomposite could be used for prevention of dental caries at low dosage.
As a chronic and infectious disease, dental caries has become a part of the heavy burdens of individuals and society, which is featured with tooth mineral loss and mainly caused by oral bacteria. Anti-caries agent should be safe, and capable of both high bacterial inhibition and remineralization, yet very few ones can meet these requirements simultaneously. In this study, a silver-doped amorphous calcium phosphate (Ag-EACP) is prepared by a biomimetic enzymatic reaction, with the in vivo energy storage biomolecule adenosine triphosphate disodium (Na 2 ATP) as the phosphorus source. Ag-EACP has an amorphous phase, with high content of ATP . The doped silver in the form of Ag + ion is stabilized against transformation, can help adjust the size of Ag-EACP. The Ag-EACP can effectively inhibit the growth of Streptococcus mutans and Lactobacillus acidophilus , two main cariogenic pathogens, both in planktonic and free states, and suppress the formation of bio-film. Moreover, this nanocomposite generates significant remineralization and micro-hardness recovery of initial caries lesion. Ag-EACP shows great anti-caries effects on initial caries lesions and is promising for caries prevention in dentistry.
Caries as a result of acid demineralization is the most common oral microbial infection disease. Due to the small and complex intraoral operating space, it is challenging to completely remove Streptococcus mutans (S. mutans) and other cariogenic bacteria. As an intelligent acid-responsive photosensitive nanomaterial, O2-Cu/ZIF-8@Ce6/ZIF-8@HA (OCZCH) was chosen to adapt the anaerobic and acidic microenvironment to inactivate S. mutans. In this work, OCZCH not only has a regular nanomorphology under the SEM and TEM images but also has an intelligent acid responsiveness as evidenced by the release of Ce6 and oxygen. When excited by near-infrared light at 650 nm, Ce6 released reactive oxygen species (ROS) that act synergistically with internal oxygen to significantly enhance the antimicrobial therapeutic effect of photodynamic therapy (PDT). In vitro, antimicrobial experiments showed that OCZCH could achieve an impressive sterilization effect against S. mutans and the biofilm. Notably, the acid-producing ability of the bacteria was also significantly inhibited. Considering its oxygen-carrying photosensitizing properties, excellent responsiveness to acidic environments, and antimicrobial capacity under anaerobic conditions, OCZCH is considered an innovative candidate for clinical application in treating dental caries.
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