Size dependent antimicrobial activity of Boerhaavia diffusa leaf mediated silver nanoparticles

Abstract

Antibacterial activities of Boerhaavia diffusa leaves (BDL) mediated silver nanoparticles (AgNPs) were studied. UV–visible spectroscopy (UV–vis), transmission electron microscopic (TEM), X-ray diffraction (XRD) and Energy-Dispersive X-ray spectroscopy (EDS) studies of the synthesized nanoparticles were analyzed too. As the concentration of Boerhaavia diffusa leaf (BDL) extract increases, a full width half maximum value decreased and blue shift observed from 427 to 420 nm in the UV–vis spectrum. The XRD confirmed the nanoparticles' high crystallinity and the average nanoparticle size calculated was 14 nm. TEM result reveals that the AgNPs are spherical in shape and the particle sizes range from 6.33 nm to 24.9 nm. The average size of AgNPs was determined to be 13.27 nm which is close to the particle size determined by XRD. EDS shows a prominent peak at 3 kev, indicating that elemental silver is a major component in the reaction medium. The produced nanoparticles were well dispersed and almost spherical in shape. The silver nanoparticles produced at higher concentration of BDL extract against Gram negative pathogen Salmonella typhi, showed higher zone of inhibition (23 mm) compared to Staphylococcus aureus (21 mm). This biosynthetic method for generating silver nanoparticles prepared in the present work has discrete compensations over chemical reduction synthesis procedures, including great biosafety, ecofriendliness and nontoxicity to the environment.

Keywords

• Boerhaavia diffusa
• Silver nanoparticles
• Spherical
• Antibacterial
• Salmonella typhi