摘要：Biosynthesis of gold nano particles (GNPs) is considered to be a novel, effective and eco-friendly method. Biosynthesis of GNPs from Benincasa hispida, Justicia gendarussa & Ocimum basilicum. Biosynthesis of stable and nearly spherical GNPs using the extract of Benincasa hispida seeds as reducing and capping agents. The particle size could be easily tuned by the reaction conditions including quantity of extract, temperature and pH. GNP shaving different sizes in the range from10-30nm could be obtained by controlling the synthesis parameters. Justicia gendarussa leaf extract mediated synthesis of GNPs by the reduction of gold ions. Three different phytochemical fractions were prepared from methanolic leaf extract by liquid-liquid extraction method using immiscible solvents. The size of the GNPs ranged from 20-42nm and 62-88nm with spherical, triangle, truncated triangle and hexagonal shapes. Ocimum basilicum (Thai Tulsi) leaf extract worked as a potential substrate for bioreduction of HAuCl4 into GNPs within 10 minutes of reaction time. It was also observed that GNPs synthesized were crystalline and uniformly spherical in shape with size range 5–40 nm which were stable even after 3 months of reaction. The gold nanoparticles were characterised by UV-Visible Spectroscopy, Transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infra red spectroscopy (FTIR), Dynamic light scattering (DLS), X-ray photoelectron spectroscopy (XPS) and Atomic Absorption Spectroscopy (AAS). Keywords : Benincasa hispida; Gold nano particles (GNPs); Justicia gendarussa; Ocimum basilicum; Transmission electron microscope (TEM).
