Parameters Affecting the Biosynthesis of Gold Nanoparticles Using the Aquatic Extract of Scrophularia striata and their Antibacterial Properties

Green synthesis is a simple, low-cost, non-toxic, environmentally friendly and efficient approach touse. Leaf extract of plants rich in polyphenols, such as flavonoids, is a powerful agent in reducing thesynthesis of gold nanoparticles. The purpose of this study is to investigate the parameters affecting thebiosynthesis of gold nanoparticles using the aqueous extract of Scrophularia striata plant and theirantimicrobial activity. Biosynthesis of gold nanoparticles was accomplished by the interaction of goldensalt (HAuCl4.3H2o) with aqueous extract of Scrophularia striata. In order to obtain uniform and sphericalnanoparticles, the following parameters affecting the biosynthesis of nanoparticles were investigatedand optimized by ultraviolet-spectrophotometric technique; golden salt concentration, extract volume,pH and reaction time. Transmission electron microscopy and X-ray diffraction technique were also usedto further characterize nanoparticles. Finally, the anti-bacterial properties of gold nanoparticles wereinvestigated by disc diffusion method. The resulting absorption spectra exhibited strong peaks at 570nm, which is a specific wavelength for gold nanoparticles. Transmission electron microscopy studiesshowed that the gold nanoparticles had a spherical shape with a mean diameter of 5-10nm, and thehighest diameter of the growth inhibition zone was observed on the diameter of the hafnium bacteria(14mm). In this study, it was observed that, with the aid of Scrophularia striata aqueous extracts, agolden nanoparticle showed an antibacterial activity against gram-negative bacteria.