Biogenic synthesis and antimicrobial activity of silica-coated silver nanoparticles for esthetic dental applications

Objectives: this study aimed to synthesize AgNPs from green tea (GT) extract, forming GT-AgNPs, and to coat their surfaces with silica, resulting in light-colored Ag@SiO2 nanoparticles. Materials and Methods: particles were characterized and tested for minimal inhibitory concentration (MIC), biofilm formation against Streptococcus mutans and cytotoxicity evaluation on dental pulp fibroblasts. Results: X-ray diffraction (XRD) confirmed the formation of pure AgNPs, whereas energy dispersive X-ray spectroscopy (EDS) mapped their elemental atoms. Dynamic light scattering (DLS) demonstrated formation of particles at nanoscale, with moderate polydispersity and negative zeta potential, in agreement with nanoparticle tracking analysis (NTA) size measurements. Fourier-transformed infrared (FTIR) spectroscopy confirmed the successful condensation of silica, which significantly increased surface area by 50%, as assayed by surface area analysis (BET). Thermogravimetric analysis showed a 18%-mass of silica on the surface of Ag@SiO(2)NPs. Transmission electron microscopy (TEM) displayed the spherical shape of nanoparticles and average size of 11 nm for GT-AgNPs and Ag@SiO(2)NPs. Ag@SiO(2)NPs demonstrated potent antimicrobial action against S. mutans, with MIC determined as 600 mu g/mL, and inhibition of approximately 44% (p < 0.05) of biofilm formation. At the MIC concentrations, both NPs did not exhibit cytotoxicity. Conclusion: Ag@SiO(2)NPs might have a useful application in dental materials. Clinical significance: The possibility of incorporating antimicrobial properties in restorative materials without compromising esthetics makes the AgNPs@SiO2 NPs promising agents against S. mutans biofilm formation, hence the prevention of dental caries. This represents a great step towards the development of more interactive biomaterials in dentistry to overcome clinical problems.