GREEN SYNTHESIS OF SILVER NANOPARTICLES USING VERBENA OFFICINALIS L. ROOT EXTRACTS AND THEIR ANTIBACTERIAL ACTIVITY AGAINST ESCHERCHIA COLI AND STAPHYLOCOCCUS AUREUS

Abstract

Green nanoparticle synthesis techniques for various biological activities and medical applications are desired because of their bio-compatibilit. Hence, in this study, silver nanoparticles (AgNPs) were synthesized using root extracts (aqueous, methanol and hexane) of V.officinalis. The antibacterial efficacy of the nanoparticles was assayed by the Kirby–Bauer disc diffusion method against bacterial pathogens such as Escherichia coli and Staphylococcus aureus. The minimum inhibitory concentration (MIC) of the synthesized AgNPs against the microorganisms was also determined. The formation of the silver nanoparticles (AgNPs) was visually observed by the colour change of the solution from milky white to deep brown. It was also characterized with Surface Plasmon Resonance using ultraviolet-visible (UV) spectroscopy. The crystal structure and functional groups were characterized by X-ray diffractometer (XRD) and Fourier transform infrared (FT-IR) spectroscopy respectively. The synthesized AgNPs exhibited good antibacterial activity against bacterial pathogens such as Escherichia coli and Staphylococcus aureus. The AgNPs from the methanol extract of V.officinalis displayed the lowest MIC (10.42 µg/ml) value against S. aureus. The results revealed that plant extracts assisted the synthesis of AgNPs as stabilizing and reducing agents and strong antibacterial activity against bacterial pathogens. Further works are required to investigate other biological activities of green synthesized silver nanoparticles.