Characterization and Bactericidal Efficacy Studies of Silver Nanoparticles Synthesized from Leaf Extract of Medicinal Plant, Ocimum basilicum

Abstract

Silver nanoparticles (AgNPs) were synthesized using the leaf extract of Ocimum basilicum, a medicinal plant, as a reducing agent. Characterization of the particles was done by UV-visible extinction spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and powder X-ray diffraction (PXRD) studies. The shapes of particles are spherical to quasi-spherical. Diffraction patterns from characteristic crystallographic planes observed in PXRD and concentric rings with bright intermittent dots observed in selected area x-ray diffraction (SAED) confirm that the silver in their nanoparticles is being crystallized into a face-centered cubic (FCC) structure. The average particle size worked out using PXRD data and the maximum of particle size distribution with respect to TEM analysis are 16 and 20 nm, respectively. Antibacterial efficacy of the synthesized AgNPs against the spreading of gram-negative bacteria, Escherichia coli and gram-positive bacteria, Staphylococcuus aureus were determined in terms of their minimum inhibitory concentration (MIC) in nutrient agar media, and the results were compared with that shown by ciprofloxacin, a reference substance. The MICs of the AgNP solutions synthesized from O. basilicum were 9.00 × 10-5 g/ mL against the spread of E. coli and 1.125 × 10-4 g/mL against S. aureus. The antibacterial efficacy determined against E. coli, in the adopted procedure, of the AgNPs synthesized using the water extract of the leaf sample of O. basilicum is superior to that exhibited by ciprofloxacin