JOURNAL OF THE IRANIAN CHEMICAL SOCIETY, cilt.16, sa.7, ss.1365-1372, 2019 (SCI-Expanded)
Due to their small particle size and high surface to volume ratio, nanoparticles exhibit new and unique properties from their bulk counterparts. One of the promising alternative synthetic routes for metal nanoparticles is green synthesis, which employs nontoxic reactants derived from the biological sources also which make them particularly attractive for use in biomedical science. Bimetallic nanoparticles often display different or better catalytic, optical and magnetic properties, and surface energy than their monometallic counterparts due to the synergism between two metallic nanoparticles. In the present study, green synthesis of Ag, Au and Ag-Au nanoparticles was reported using the aqueous extract of turmeric powder. Phytochemicals found in the extract resulted in formation of Ag, Au and Ag-Au nanoparticles by reducing their ions to metallic form. The synthesized nanoparticles were characterized with UV-Vis spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). Also an immediate color change in the extract after addition of salts confirmed the formation of nanoparticles by reduction reactions. It was observed that SPR absorption peak for Au and Ag-Au nanoparticles at 534 and 534 nm respectively. While for Ag nanoparticles the certain absorption peak could not be observed, the obvious shoulder in the range of 430-460 nm confirmed the presence of Ag nanoparticles in the extract. The structures of nanoparticles synthesized were confirmed as crystalline form by XRD. The mean diameter of Ag, Au and bimetallic Ag-Au nanoparticles were found to be as 4±5, 9±7 and 12±4 nm respectively, by evaluating TEM images with Adobe Photoshop 7. Mostly, spherical shape was observed for the nanoparticles in TEM images. It is concluded that the confirmed method in this work is cost-effective and environmentally friendly. Thus, it can be used safely and effectively in the synthesis of Ag, Au and Ag-Au nanoparticles instead of chemical methods.