Phytosynthesis of Silver Nanoparticles Using Walnut (Juglans regia) Bark with Characterization of the Antibacterial Activity against Streptococcus mutans

ABSTRACT

A green method using Juglans regia bark extract was used to synthesize silver nanoparticles at room temperature with monitoring by absorption spectroscopy. The size and shape of the synthesized nanoparticles were characterized by infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, high-resolution transmission electron microscopy, and small-angle X-ray scattering. The average particle size was from 10 to 30 nm. Gas chromatography–mass spectrometry (GC–MS) was used for the separation, identification, and quantification of components of the plant extracts. A possible mechanism for the synthesis of nanoparticles was elucidated based on the GC–MS results. The synthesized silver nanoparticles showed effective inhibition against Streptococcus mutans, which is the main causative agent for dental caries. The nanoparticles also showed promising antibiofilm activity by inhibiting the glucosyltransferase enzyme.

KEYWORDS:

• Biological synthesis
• glucosyltransferase enzyme
• Juglans regia
• silver nanoparticles
• Streptococcus mutans

Acknowledgments

The authors would like to acknowledge SAIF IIT Bombay for transmission electron microscopy and high-resolution transmission electron microscopy and the Nanomaterials Research Lab, Department of Condensed Matter Physics and Materials Science, TIFR, Mumbai for scanning electron microscopy.