Effect of Gold Chloride Concentration and Volume on Size and Shape of Biological Synthesized Gold Nanoparticles (AuNPs) Using Red Algae (Laurencia papillosa)

摘要

Gold nanoparticles (AuNPs) were successfully synthesized using an eco-friendly method in a single-step reaction with red algae (Laurencia papillosa). In this research we investigated the factors that affect the characteristics of AuNPs, such as the size, shape, surface profile and surface chemistry. The synthesized AuNPs were characterized using UV-Visible spectroscopy, X-ray diffraction (XRD), Transmission Electron Microscope (TEM), Field Emission Scanning Electron microscope (FESEM), and Atomic Force Microscope (AFM) measurements. Computational analysis of the size distribution, surface profile, area and value of the different AuNPs synthesized were carried out using freeware ImageJ. The study revealed that the color of the solutions of HAuCl4 was changed from yellow to ruby red indicating that metallic gold nanoparticles were synthesized. TEM images of the synthesized AuNPs showed different shapes and sizes ranging from 3.5 to 53 nm at lambda(max) = 586 nm in different concentrations (Graphical Abstract). The resulting shapes were spherical and triangular crystalline gold nanoparticles with varied oxidation states of Au (0) and Au (+1). One of our future goals in Plant Virology is the use of these gold nanoparticles as a carrier in biological control of plant virus diseases using viral satellite RNA as a biological control agent against severe plant virus diseases (United States Patent No. US 8,138,390 B2). The functional groups in the algal extract responsible for the synthesis of the AuNPs were identified to be NH2+ and OH-groups. The optimum ratio of Au/Algal extract required for producing small sizes of AuNPs was found to be 1:2. The Algal water-extract has dual functions in this synthesis-: they act as reducing and stabilizing agent. AuNPs have many biological, industrial and medical applications which include treatments against plant virus and cancer diseases.