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Synthesis of Gold Nanoparticles - Beloit College

T1 - Green Synthesis of Gold Nanoparticles Coupled with Nucleic Acid Oxidation

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Three Syntheses of Gold Nanoparticles

Green synthesis of metal nanoparticles, especially gold nanoparticles (AuNPs), has attracted the great interest of scientists and engineers in the medical and pharmaceutical fields; thus, a variety of ecofriendly, energy- and cost-saving techniques have been developed. In this study, we found that cells of Leptothrix (iron-oxidizing bacteria) released extracellular RNA some of which could exist as a constituent of the cell-enclosing sheaths. As a part of studies of metal encrustation in the sheaths, here we show that RNA prepared from the Leptothrix cells can reduce Au(III) and spherical AuNPs eventually form when an aqueous HAuCl4 solution is added under ambient conditions. RNA and DNA of other organismal origins have the same ability. Of the nucleosides and nucleobases, only guanosine and guanine can form AuNPs. The DNA moiety, 2′-deoxyguanosine (dG) (used as a reference material), forms AuNPs when mixed with HAuCl4 solution, but 8-hydroxy-2′-deoxyguanosine (8-OHdG) does not, indicating that AuNP formation evidently depends on the reduction potential of the guanine moiety, not the sugar moiety. This finding is the first demonstration that spherical AuNPs of ca. 5 nm diameter can be obtained by simply adding guanine to HAuCl4 solution at ambient temperature; no other chemicals or physical treatments are needed.

29/12/2010 · Gold Nanoparticle Synthesis, Morphology Control, ..

AB - Green synthesis of metal nanoparticles, especially gold nanoparticles (AuNPs), has attracted the great interest of scientists and engineers in the medical and pharmaceutical fields; thus, a variety of ecofriendly, energy- and cost-saving techniques have been developed. In this study, we found that cells of Leptothrix (iron-oxidizing bacteria) released extracellular RNA some of which could exist as a constituent of the cell-enclosing sheaths. As a part of studies of metal encrustation in the sheaths, here we show that RNA prepared from the Leptothrix cells can reduce Au(III) and spherical AuNPs eventually form when an aqueous HAuCl4 solution is added under ambient conditions. RNA and DNA of other organismal origins have the same ability. Of the nucleosides and nucleobases, only guanosine and guanine can form AuNPs. The DNA moiety, 2′-deoxyguanosine (dG) (used as a reference material), forms AuNPs when mixed with HAuCl4 solution, but 8-hydroxy-2′-deoxyguanosine (8-OHdG) does not, indicating that AuNP formation evidently depends on the reduction potential of the guanine moiety, not the sugar moiety. This finding is the first demonstration that spherical AuNPs of ca. 5 nm diameter can be obtained by simply adding guanine to HAuCl4 solution at ambient temperature; no other chemicals or physical treatments are needed.

Gold Nanoparticles synthesis | Gold nanoparticle Conjugation

Gold nanoparticles are commonly synthesized by reducing tetrachloroauric acid with trisodium citrate, a method pioneered by Turkevich et al (

Highly monodisperse sodium citrate-coated spherical silver nanoparticles (Ag NPs) with controlled sizes ranging from 10 to 200 nm have been synthesized by following a kinetically controlled seeded-growth approach via the reduction of silver nitrate by the combination of two chemical reducing agents: sodium citrate and tannic acid. The use of traces of tannic acid is fundamental in the synthesis of silver seeds, with an unprecedented (nanometric resolution) narrow size distribution that becomes even narrower, by size focusing, during the growth process. The homogeneous growth of Ag seeds is kinetically controlled by adjusting reaction parameters: concentrations of reducing agents, temperature, silver precursor to seed ratio, and pH. This method produces long-term stable aqueous colloidal dispersions of Ag NPs with narrow size distributions, relatively high concentrations (up to 6 × 1012 NPs/mL), and, more important, readily accessible surfaces. This was proved by studying the catalytic properties of as-synthesized Ag NPs using the reduction of Rhodamine B (RhB) by sodium borohydride as a model reaction system. As a result, we show the ability of citrate-stabilized Ag NPs to act as very efficient catalysts for the degradation of RhB while the coating with a polyvinylpyrrolidone (PVP) layer dramatically decreased the reaction rate.

(2016) 'Anisamide-targeted gold nanoparticles for siRNA delivery in prostate cancer - synthesis, physicochemical characterisation and in vitro evaluation', Journal of Materials Chemistry B, 4(13), pp.

Green Synthesis of Gold Nanoparticles : Oriental …

01/06/2014 · Gold nanoparticles: various methods of synthesis and ..

Continuous flow microfluidic reactors offer some advantages over conventional batch based methods: straight forward up-scaling, on-line monitoring of the products for easy process control, improved reaction yield, selectivity, and kinetics by exploring a wider parameter space for external parameters like pressure and temperature, and improved reactant mixing. Miniaturization of the flow channels allows the change of experimental conditions along the reaction path within microseconds and greatly reduces the volume required to test certain experimental parameters (to microliters or even nanoliters). The wet-chemical synthesis of spherical gold nanoparticles has a long history dating back to Michael Faraday and was recently adapted to continuous flow reactions. During the past 5 years, the high yield batch synthesis of elongated, rod-shaped gold particles was achieved in ‘soft templates’ – tubular micelles formed in concentrated solutions of surfactants. Here, spherical seeds are grown into nanorods in a growth solution. We show here the first example of a continuous flow synthesis of nanoparticles with a rod-like shape, specifically gold and silver nanorods.

N2 - Green synthesis of metal nanoparticles, especially gold nanoparticles (AuNPs), has attracted the great interest of scientists and engineers in the medical and pharmaceutical fields; thus, a variety of ecofriendly, energy- and cost-saving techniques have been developed. In this study, we found that cells of Leptothrix (iron-oxidizing bacteria) released extracellular RNA some of which could exist as a constituent of the cell-enclosing sheaths. As a part of studies of metal encrustation in the sheaths, here we show that RNA prepared from the Leptothrix cells can reduce Au(III) and spherical AuNPs eventually form when an aqueous HAuCl4 solution is added under ambient conditions. RNA and DNA of other organismal origins have the same ability. Of the nucleosides and nucleobases, only guanosine and guanine can form AuNPs. The DNA moiety, 2′-deoxyguanosine (dG) (used as a reference material), forms AuNPs when mixed with HAuCl4 solution, but 8-hydroxy-2′-deoxyguanosine (8-OHdG) does not, indicating that AuNP formation evidently depends on the reduction potential of the guanine moiety, not the sugar moiety. This finding is the first demonstration that spherical AuNPs of ca. 5 nm diameter can be obtained by simply adding guanine to HAuCl4 solution at ambient temperature; no other chemicals or physical treatments are needed.

Wet chemical synthesis of gold nanoparticles using …
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    Introduction

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Green Synthesis of Metallic Nanoparticles via ..

Open and discussed questions are: the source and reason for anisotropic growth in general, accompanied by the surprisingly high yield of anisotropic particles. Those fundamental questions are important not only for gold nanorod synthesis, but insights into the growth may also help to tune and understand growth of other materials or different shapes. Furthermore, in the light of the above mentioned effects, it is critical to carefully control and tune the gold nanorod growth in order to achieve a uniform nanoparticle distribution and thereby uniform properties.

DropSens ::.. Nanomaterials. Electrochemical reagents.

The polymerization of n-butyl acrylate further protected the QDs from degradation via chemical reaction, and the resulting materials were both well-distributed on the nanoscale and possessed the optical properties expected from quantum dots of their size.


A one-pot synthesis of thermally stable core/shell gold nanoparticles (Au-NPs) was developed via surface-initiated atom transfer radical polymn.

Surface modification, functionalization and …

Hypoxia is regarded as a key feature of the tumor microenvironment that significantly influences tumor treatment response. An albumin-stabilized gold nanoparticle was synthesized for tumor hypoxia imaging (Figure a) []. The nanoparticle was modified with hypoxia-sensitive nitroimidazole moiety, which was converted into amine groups in the presence of nitroreductase. Conversion from the nitro group of nitroimidazole to the amino group helped increase the zeta potential of the prepared nanoparticle, which thereby improved cell internalization for accumulation at the tumor . The designed nanoparticle displayed enhanced X-CT imaging for tumor hypoxia

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