Populus ciliata mediated synthesis of silver nanoparticles and their antibacterial activity

Design and synthesis of bactericidal and fungicidal agents is very important to protect human beings from different diseases. Silver nanoparticles (AgNPs) possess good bactericidal properties. Synthesis of these nanoparticles (NPs) via green route is cost-effective and environmentally harmonious as compared to the chemical and physical approaches. In this work, AgNPs were synthesized through green synthesis method using Populus ciliata leaf extract. The synthesized AgNPs were characterized by x-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive x-ray (EDX) techniques. The XRD pattern depicted the characteristic Bragg's peaks of (111), (200), (220), and (311) planes which are the features of face centered cubic (FCC) geometry of the synthesized AgNPs. TEM micrographs revealed the spherical shaped particles having average size of 4 nm. The AgNPs showed inhibitory effects against selected gram positive (Staphylococcus epidermidis and Streptococcus pyogenes) and gram negative bacteria (Klebsiella pneumoniae, Serratia marcescens, and Pseudomonas pseudoalcaligenes). The maximum zone of inhibition (26 mm) was observed for gram negative bacterium (Serratia marcescens) when 25 mg/ml solution of AgNPs was used and for similar concentration of these NPs, the maximum zone of inhibition (25 mm) was observed against gram positive bacteria (S. pyogenes). The results indicated good bactericidal potential of the synthesized AgNPs. RESEARCH HIGHLIGHTS: Populus ciliata leaf extract mediated synthesis of AgNPs. Transmission electron microscopy analysis revealed very small size of the synthesized AgNPs (4 nm). The synthesized AgNPs were found very effective against various bacterial pathogens.

Keywords: AgNPs; Populus ciliata; antibacterial activity; green synthesis; transmission electron microscopy.