Phyto-Mediated silver nanoparticles via melissa officinalis aqueous and methanolic extracts: Synthesis, characterization and biological properties against infectious bacterial strains

The present study was aimed to examine the influence of extraction method on the morphology, physico-chemical characteristics and antimicrobial properties of silver nanoparticles (AgNPs) synthesized from Melissa officinalis. AgNPs were prepared by two extraction methods. The properties of obtained nanoparticles were characterized by SEM, UV-Vis, XRD and FTIR techniques. SEM images showed different shape, size and morphology of AgNPs using two different extracts types. The UV-Vis spectroscopy confirmed the formation of AgNPs by observing a distinct surface Plasmon resonance band around 450 nm. SEM images showed different shape, size and morphology of AgNPs using two different extracts types. AgNPs derived from the aqueous extract were rod-shaped with a diameter of 19 to 40 nm whereas spherical particles were synthesized by the methanolic extract found smaller with size distribution ranging from 13 to 35 nm. The XRD pattern indicated that AgNPs formed by the reduction of Ag+ ions using the methanolic extract were crystal-like in nature. The functional groups of the methanolic extract involved in synthesis and stabilization of AgNPs were investigated by FTIR. In addition, AgNPs containing methanolic extract showed higher antioxidant activity. The disc diffusion and agar well diffusion methods revealed the antimicrobial potential of these particles exhibited remarkable antimicrobial activity against Gram positive and Gram negative bacteria and a fungus. The production of silver nanoparticles using plant extract is rapid, low cost and eco-friendly. Silver nanoparticles can be used as an antiseptic to sterilize the surrounding area and the hospital wastes.