International Journal of Scientific & Engineering Research, Volume 5, Issue 1, January-2014 1832 ISSN 2229-5518 IJSER © 2014 http://www.ijser.org Biosynthesis of Cubic Gold nanoparticles M. Jannathul Firdhouse and P. Lalitha* Department of Chemistry Avinashilingam Institute for Home Science and Higher Education for Women University Coimbatore-641043, Tamil Nadu, India. *Corresponding author: goldenlalitha@gmail.com Abstract Green leafy vegetable (Amaranthus dubius) was used as reductant and capping agent for the synthesis of gold nanoparticles. The nanogold synthesis was carried out under various conditions to evaluate the rate of reduction of gold ions. The formation of gold nanoparticles was monitored by UV-visible spectroscopy. The shape of the nanogold was found to be spherical and the size was analyzed by XRD and SEM analysis. The FTIR measurements confirm that the protein molecule present in the extract aids the formation of gold nanoparticles. Hence green leafy vegetable mediated synthesis of gold nanoparticles may find applications in nutraceuticals. Key words: Amaranthus dubius, gold nanoparticles, XRD, SEM. ——————————  —————————— 1 INTRODUCTION In the present scenario, the herbs have created a revolution symbolizing the importance and safety in contrast to the synthetic drugs all over the world. Of the world’s population, 20% people are still using natural products as medicine. Green plants naturally synthesize various biochemical products which can be used as food, feed stocks and raw materials as drugs to provide scientific innovation [1]. Plants are good source of secondary metabolites which find use in the pharmaceutical research. In past years a large percentage of commercially available new drugs are from natural products. Hence biological synthesis of products has to be implemented for new findings [2]. Amaranthus plants (Amaranthaceae) grows under a wide range of climatic conditions and serves as useful feed, food products as cooked vegetables and in traditional medicine. The leaves of amaranth are a rich source of protein, carotenoids, vitamin C, dietary fiber and minerals. Amaranthus dubius is recommended for anaemia, kwashiorkor, insomnia, stomach ache and also for young children and nursing mothers due to its high protein content. The essential amino acids composition of the proteins isolated from the leaves of A. dubius are albumins (Asp, Glu and Arg), globulins (Lys, Arg and Leu) and glutelins (Lys, Arg and Glu). The biological value of the proteins present in A.dubius is higher compared to that of wheat proteins and soya beans [3, 4, 5]. In modern material science, nanotechnology field is the most attractive area of research. The improved properties such as optical, electronic, magnetic and catalytic depend on their size, distribution and morphology. Nanoparticles synthetic protocols involve toxic chemicals which can cause adverse effects in medical applications. Hence there is a need to develop eco-friendly and sustainable methods of synthesis. Gold nanoparticles have received attention due to its unique properties and surface Plasmon resonance and finds application in drug delivery, chemotherapeutics, catalyst, biosensors and biomedical fields [6, 7, 8, 9, 10, 11, 12, 13, 14]. Polyhedral gold nanocrystals like cubes, tetrahedrons, octahedrons exhibit high index facets and branched nanocrystals (stars, dendimers) have received more attention due to its applications in catalysis, plasmonics and SERS based sensors. But, most of the synthetic methods yield only gold nanoparticles of polyhedral with convex shapes of low index facets (111), (100) and (110). Efforts were put forward for the synthesis of gold nanoparticles with high index facets due to their higher catalytic activities than the low index facets [15]. Biosynthesis of gold nanoparticles is found to be non-toxic, cost effective and rapid synthesis. There are reports on the exploration of plant mediated synthesis of gold nanoparticles IJSER