Scrophularia striata extract mediated synthesis of gold nanoparticles; their antibacterial, antileishmanial, antioxidant, and photocatalytic activities

The green technique for the preparation of different nanoparticles is an eco-friendly, economically, and safe technology. In this research, Gold nanoparticles (SS-AuNPs) were prepared by the rapid, inexpensive and ecofriendly process using Scrophularia striata extract as a reducing, capping, and stabilizing agent for the first time. The formation of nanoparticles was confirmed using various analytical methods, including UV/Vis, XRD, EDX, TEM, FT-IR, FE-SEM techniques. UV-Vis data indicated the "surface plasmon resonance" band at 575 nm. The electron microscopy data exhibited that synthesized AuNPs had mostly spherical in shape with a mean crystaline size of 34.6 nm. The spherical crystalline nature of the synthesized NPs was demonstrated by the XRD analysis and the average size was determined at 21.35 nm. Prepared SS-AuNPs exhibited good antibacterial activity against tested bacteria. The MIC values of 11.875, 95, 47.5, 47.5, 23.75, 11.875, and 47.5 & mu;g/ml on strains Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, Acinetobacter baumannii, Escherichia coli, Klebsiella pneumonia, and Proteus mirabilis were determined respectivly. Also, SS-AuNPs showed effective antileishmanial activity, the anti-promastigotes activity of SS-AuNPs was calculated as IC50 values of 0.12 & mu;g/ml and the anti-amastigote activity of SS-AuNPs was determined as IC50 values of 0.07 & mu;g/ml. Potentially inhibited DPPH ( 2,2-diphenyl-1-picrylhydrazyl) radicals (IC50 = 15.81 & mu;g/ml). Synthesized gold nanoparticles as a noble nanocatalyst act for the reduction of methyl orange (MO) that was in the presence of visible light and sodium borohydride. Where 50 & mu;l of prepared AuNPs, completely degraded MO dye in 5 min. The results of this study indicate that gold nanoparticles, which were mediated by S. stratia extract, possess great potential for application in a wide range of fields, such as industrial wastewater treatment and biomedical sectors.