convenient and cost-effective plant-mediated synthesis of gold nanoparticles using moringa oleifera l. and study of their antimicrobial activities

Plants have received much attention as sustainable and available sources for the preparation of biocompatible nanoparticles in recent years. the purpose of the present study is to optimize and characterize the biosynthesis of gold nanoparticles using the aqueous extract of moringa oleifera l. after simple processing of the plant, plant powder was heated at 30 °c. in the following, optimum volume of the prepared extract, was added to determined amount of gold salt (haucl4.3h2o) with a specific concentration, which reduced the gold (iii) ions to gold atoms in nanometric dimensions and immediately changed the color of the solution to purple. to obtain gold nanoparticles with uniform shape and size, the parameters affecting the synthesis, such as ph of the reaction medium, volume of the extract, concentration of gold salt, temperature, and reaction time, were studied and optimized using ultraviolet-visible spectrophotometry. gold nanoparticles showed maximum absorption at 550 nm. it was found that the synthesized nanoparticles were spherical in shape and their size was between 10-40 nm. finally, the antimicrobial properties of the nanoparticles were investigated on 4 pathogenic bacteria species by disk diffusion method, which showed that gold nanoparticles have relatively good antimicrobial activity against some bacteria.