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Here, we report the high yield synthesis of different shaped gold nano particles (AuNPs) through seed mediated growth process in aqueous medium. Shape dependent surface plasmon resonance (SPR) and the gradual shift of longitudinal SPR band are observed with increasing anisotropy of AuNPs. Structural changes during the growth processes are observed by transmission electronic microscopy (TEM). Here, spherical nano seeds are transformed into rice and dendrimer shaped nanoparticles in the subsequent four stage growth processes. Gold nanoparticles have been demonstrated to be very efficient catalysts for the cleavage of N N of sudan-1 and it is investigated by monitoring the reduction of sudan-1 in the presence of excess NaBH 4 . It has been observed that the reaction is first order with respect to the concentration of sudan-1 and the catalytic efficiency of dendrimer shaped AuNPs is higher than the other as synthesized AuNPs. [ABSTRACT FROM AUTHOR]

Abstract: Methyl cellulose (MC) capped gold nanoparticles are successfully prepared through a simple route. Synthesis is based on the reduction of aqueous HAuCl4.4H2O by hydrogen gas at 85°C and methyl cellulose has been used as encapsulating agent. Gold nanoparticle so-prepared are characterized by UV–Vis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and high resolution transmission electron microscopy (HR-TEM). Methyl cellulose encapsulated gold hydrosol shows broad surface plasmon resonance (SPR) band with maxima at 537nm along with a broad tail at 635nm. In accordance with the SPR band, HRTEM micrograph shows two broad distributions of particles, most of them are small and spherical and nearly 25% particles are bigger with uneven shapes. [Copyright &y& Elsevier]