title: Microbial synthesis of multishaped gold nanostructures.
abstract: The development of methodologies for the synthesis of nanoparticles of well-defined size and shape is a challenging one and constitutes an important area of research in nanotechnology. This Full Paper describes the controlled synthesis of multishaped gold nanoparticles at room temperature utilizing a simple, green chemical method by the interaction of chloroauric acid (HAuCl4 x 3H20) and cell-free extract of the fungal strain Rhizopus oryzae. The cell-free extract functions as a reducing, shape-directing, as well as stabilizing, agent. Different shapes of gold nanocrystals, for example, triangular, hexagonal, pentagonal, spherical, spheroidal, urchinlike, two-dimensional nanowires, and nanorods, are generated by manipulating key growth parameters, such as gold ion concentration, solution pH, and reaction time. The synthesized nanostructures are characterized by UV/Vis and Fourier-transform infrared spectroscopy, transmission electron microscopy, and energy dispersive X-ray analysis studies. Electron diffraction patterns reveal the crystalline nature of the nanoparticles and a probable mechanism is proposed for the formation of the different structural entities.
authors.affiliation: Department of Biological Chemistry, Indian Association for the Cultivation of Science, Kolkata, India.
authors.forename: Sujoy K
authors.initials: SK
authors.lastname: Das
authors.forename: Akhil R
authors.initials: AR
authors.lastname: Das
authors.forename: Arun K
authors.initials: AK
authors.lastname: Guha
mesh_terms: D002474:Cell-Free System / Q000737:chemistry*; D002712:Chlorides / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D017612:Gold Compounds / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods; D010316:Particle Size; D012233:Rhizopus / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D002712:Chlorides; D017612:Gold Compounds; D046911:Macromolecular Substances; D006046:Gold; C024568:gold tetrachloride, acid