'Green' silver nanoparticles combined with tyrosol as potential oral antimicrobial therapy.

OBJECTIVES: This study aimed to evaluate silver nanoparticles (AgNPs) obtained by a 'green' route associated or not to tyrosol (TYR) against Streptococcus mutans and Candida albicans in planktonic and biofilms states. METHODS: AgNPs were obtained by a 'green' route using pomegranate extract. The minimum inhibitory concentration (MIC) against S. mutans and C. albicans was determined for AgNPs and TYR combined and alone, and fractional inhibitory concentration index (FICI) was calculated. Single biofilms of C. albicans and S. mutans were cultivated for 24 h and then treated with drugs alone or in combination for 24 h. RESULTS: AgNPs and TYR were effective against C. albicans and S. mutans considering planktonic cells alone and combined. The MIC values obtained for C. albicans was 312.5 µg/mL (AgNPs) and 50 mM (TYR) and for S. mutans was 78.1 µg/mL (AgNPs) and 90 mM (TYR). The combination of these antimicrobial agents was also effective against both microorganisms: 2.44 µg/mL/0.08 mM (AgNPs/TYR) for C. albicans and 39.05 µg/mL /1.25 mM (AgNPs/TYR) for S. mutans. However, synergism was observed only for C. albicans (FICI 0.008). When biofilm was evaluated, a reduction of 4.62 log10 was observed for S. mutans biofilm cells treated with AgNPs (p < 0.05, Tukey test). However, the addition of TYR to AgNPs did not improve their action against biofilm cells (p > 0.05). AgNPs combined with TYR demonstrated a synergistic effect against C. albicans biofilms. CONCLUSIONS: These findings suggest the potential use of AgNPs with or without TYR against C. albicans and S. mutans, important oral pathogens. CLINICAL SIGNIFICANCE: AgNPs obtained by a 'green' route combined or not with TYR can be an alternative to develop several types of oral antimicrobial therapies and biomaterials.

Effect of nanometric ß-calcium glycerophosphate supplementation in conventional toothpaste on enamel demineralization: An in vitro study.

The aim of this study was to evaluate the effects of supplementing toothpastes containing 1100 ppm F with micrometric or nanometric [beta]-calcium glycerophosphate (ß-CaGPm/ß-CaGPn) on artificial enamel demineralization, using a pH cycling model. Bovine enamel blocks (4 mm × 4 mm, n = 120) selected using initial surface hardness were randomly allocated to ten toothpaste groups (n = 12): without fluoride or ß-CaGPm or ß-CaGPn (Negative control), 1100 ppm F (1100 F), and 1100 ppm F plus 0.125%, 0.25%, 0.5%, and 1.0% of ß-CaGPm or ß-CaGPn. Blocks were treated two times per day with toothpaste slurry and subjected to five pH cycles (demineralizing and remineralizing solutions) at 37 °C. The final surface hardness, percentage of surface hardness loss (%SH), cross-sectional hardness (ΔKHN), and profile analysis and lesion depth subsurface were analysed using polarized light microscopy (PLM). Fluoride (F), calcium (Ca), and phosphorus (P) concentrations were also measured. Data were analysed using ANOVA and Student-Newman-Keuls tests ([alpha] = 0.001). Blocks treated with 1100 F toothpaste containing 0.5%ß-CaGPm or 0.25%ß-CaGPn showed with reduced %SH values when compared with those treated with 1100 F alone (p < 0.001). Reduced lesion depths (ΔKHN and PLM) were observed for the slurry made up of 1100 F and 0.25%ß-CaGPn (p < 0.001). The addition of ß-CaGPm and ß-CaGPn did not influence the enamel F concentration, with the 1100 F/0.25%ß-CaGPn group exhibiting the highest Ca and P enamel concentrations (p < 0.001). Based on the findings of this in vitro study, we can conclude that the fluoride toothpaste produced a superior effect when combined at an appropriate ß-CaGP molar ratio. This effect was achieved with a lower proportion of ß-CaGP in the form of nanometric particles.

Antimicrobial Potential and Cytotoxicity of Silver Nanoparticles Phytosynthesized by Pomegranate Peel Extract.

The phytosynthesis of metal nanoparticles is nowadays attracting the increased attention of researchers and is much needed given the worldwide matter related to environmental contamination. The antimicrobial activity of colloidal and spray formulation of silver nanoparticles (AgNPs) synthesized by pomegranate peel extract against Candida albicans and Staphylococcus aureus, and their cytotoxicity in mammalian cells were tested in the present study. Dry matter, pH, total phenolics, and ellagic acid in the extract were determined. Then, AgNPs were phytosynthesized and characterized by X-ray diffraction, electron transmission microscopy, dynamic light scattering, zeta potential, and Ag⁺ dosage. Spray formulations and respective chemical-AgNP controls were prepared and tested. The peel extract reduced more than 99% of Ag⁺, and produced nanoparticles with irregular forms and an 89-nm mean size. All AgNP presented antimicrobial activity, and the spray formulation of green-AgNP increased by 255 and 4 times the effectiveness against S. aureus and C. albicans, respectively. The cytotoxicity of colloidal and spray green-AgNP was expressively lower than the respective chemical controls. Pomegranate peel extract produced stable AgNP with antimicrobial action and low cytotoxicity, stimulating its use in the biomedical field.