Advances in Nanoparticles, 2012, 1, 79-85 http://dx.doi.org/10.4236/anp.2012.13011 Published Online November 2012 (http://www.SciRP.org/journal/anp) Pin Oak (Quercus palustris) Leaf Extract Mediated Synthesis of Triangular, Polyhedral and Spherical Gold Nanoparticles Jonathan D. Judy 1 , N. V. K. V. Prasad Tollamadugu 2* , Paul M. Bertsch 1 1 Department of Plant and Soil Sciences, University of Kentucky, Lexington, USA 2 Institute of Frontier Technology, Regional Agricultural Research Station, Acharya NG Ranga University, Tirupati, India Email: * tnvkvprasad@gmail.com Received August 29, 2012; revised October 3, 2012; accepted October 15, 2012 ABSTRACT Fabrication of phytogenic metal nanoparticles is a developing area of nanobiotechnology which has economic and po- tentially eco-friendly advantages over conventional chemical and physical synthesis methods. We report the synthesis of anisotropic gold nanostructures using a phytoextract from the leaves of the pin oak tree, Quercus palustris. We used 2.5%, 5%, and 10% m/v extract concentrations to determine the importance of pin oak phytoextract concentration on the properties of the nanomaterials synthesized. Characterization of the resulting nanomaterials revealed that the con- centration of the phytoextract is a key factor controlling the size and relative frequency of shapes the gold nanostruc- tures formed. TEM micrographs demonstrate that triangular, spherical, and polyhedral gold nanostructures were formed in all treatments, although UV-Vis spectra indicated that the formation of fewer nanostructures in the 2.5% m/v phyto- extract treatment We found that anisotropic nanostructures are formed at the highest concentrations in the preparation using 10% m/v phytoextract. UV-Vis, TEM, and DLS data indicate that the 5% m/v phytoextract results in the synthesis of the smallest sized nanoparticles. Keywords: Biosynthesis; Phytogenic; Phytonanotechnology; Biogenic; Anisotrops 1. Introduction Nanoparticles (NPs) are of great interest due to their small size and large surface area to volume ratio. The most common method of synthesizing noble metal nano- structures is via reduction of the metal salt with a suitable reducing agent in the presence of a stabilizer [1]. How- ever, the ability to synthesize anisotropic noble metal nanostructures with high yield remains a challenge as the prevailing protocol requires complex and time-consum- ing steps. Moreover, there is a growing demand for the development of clean, non-toxic, bio-compatible and ecofriendly methods for the synthesis of metal NPs. Biogenic synthesis methods are generally considered to be safe, cost-effective, and adaptable to the large scale production of metallic nanostructures. Current trends in metal nanostructure synthesis focus on monodispersity of size and selectivity of shape, both of which are the key for manipulating the unique mag- netic, catalytic, optoelectronic, and mechanical properties of nanomaterials [2]. Control of the particle shape and size is essential for modified surface plasmon resonance (SPR) properties exploited for the development of optical and near-infrared metamaterials [3]. Gold (Au) and silver (Ag) nanomaterials exhibit important shape dependent properties [2,4]. Nanotriangles exhibit two or more pro- minent absorption bands, one a transverse absorption band in the visible region and the other a longitudinal ab- sorption band in NIR region, which are similar to proper- ties observed for nanorods [4,5]. The NIR region is of significant biological importance since it represents the only spectral window for both therapeutic and imaging applications in biological tissue which do not have sig- nificant absorption in the NIR region. Therefore, Au nanotriangles with strong NIR absorption could find po- tential applications in such areas as surface enhanced raman spectroscopy (SERS) substrates [6], infrared ra- diation absorbing optical coatings [7], and wave guides for electromagnetic radiation. Further, Au NPs have been used in protein assays [8], immunoassays [9], capillary electrophoresis [10], and as thermal scalpels to kill can- cer cells [11,12]. Biosynthesis of both isotropic and anisotropic NPs has been demonstrated with a variety of biomolecules including chitosan [13], enzymes [14] and plant extracts. Trian- * Corresponding author. Copyright © 2012 SciRes. ANP