Medicinal Plant Extract Mediated Green Synthesis and Stabilization of Silver Nanoparticles using Plumbago zeylanica L: Characterization and Assessment of Bactericidal Activity

Abstract

Water extract of a medicinal plant, Plumbago zeylanica L, is used to synthesize and stabilize the silver nanoparticles (AgNPs). Particles were characterized using UV-visible extinction spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and powder X-ray diffraction (PXRD) studies. Phenolic compounds and flavonoids present in the extract, as confirmed by the systematic qualitative phytochemical analyses, reduce silver nitrate into metallic silver. The resulting 10 nm sized particles are spherical in shape and confined to a facecentered- cubic (FCC) structure. Bactericidal effect of AgNPs was determined against the spreading of gram-negative bacteria, Escherichia coli (E. coli) and gram-positive bacteria, Staphylococcuus aureus (S. aureus) and the results were compared with antibacterial effect exhibited by a commercial standard ciprofloxacin. The bactericidal efficacy was determined in terms of minimum inhibitory concentrations (MIC) of the AgNPs in the solid solution of nutrient agar media and was found to be 37.625 ×10−5 g/mL and 43.0 × 10-4 g/mL against E. coli and S. aureus, respectively.