scholarly journals SYNTHESIS AND CATALYTIC ACTIVITY OF BRANCHED GOLD NANOPARTICLES IN AQUEOUS MEDIUM

2018 ◽  
Vol 55 (5B) ◽  
pp. 227
Author(s):  
Phan Ha Nu Diem
Keyword(s):  
Electron Microscopy ◽  
Aqueous Solution ◽  
Transmission Electron Microscopy ◽  
Gold Nanoparticles ◽  
Kinetic Data ◽  
Gold Nanostructures ◽  
Simple Method ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Experimental Parameters

In this article, a simple method for the preparation of multi–branched gold nanoparticles from an aqueous solution of silver seeds, cetyl-trimethylammonium bromide (CTAB), HAuCl4, and Pluronic F–127 was described. It was found that morphologies and sizes of gold nanostructures (AuNPs) depended strongly on such experimental parameters as concentrations of Pluronic F–127 and Au3+. The products were characterized by transmission electron microscopy (TEM). Interestingly, the multi – branched AuNPs were found to serve as an effective catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of NaBH4. Kinetic data have been obtained from monitoring the concentrations of 4-NP and BH4‒ by UV‒vis spectroscopy.

scholarly journals Effects of Different Surfactant Charges on the Formation of Gold Nanoparticles by the LASiS Method

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2937
Author(s):  
Muhammad Zulfajri ◽  
Wei-Jie Huang ◽  
Genin-Gary Huang ◽  
Hui-Fen Chen
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gold Nanoparticles ◽  
Laser System ◽  
Synthesis Process ◽  
Au Nps ◽  
Laser Fluences ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
532 Nm

The laser ablation synthesis in solution (LASiS) method has been widely utilized due to its significant prospects in laser microprocessing of nanomaterials. In this study, the LASiS method with the addition of different surfactant charges (cationic CTAB, nonionic TX-100, and anionic SDS) was used to produce Au NPs. An Nd:YAG laser system at 532 nm excitation with some synthetic parameters, including different laser fluences, ablation times, and surfactant concentrations was performed. The obtained Au NPs were characterized by UV-Vis spectroscopy, transmission electron microscopy, and zeta potential analyzer. The Au NPs exhibited the maximum absorption peak at around 520 nm for all samples. The color of Au NPs was changed from red to reddish by increasing the laser fluence. The surfactant charges also played different roles in the Au NPs’ growth during the synthesis process. The average sizes of Au NPs were found to be 8.5 nm, 5.5 nm, and 15.5 nm with the medium containing CTAB, TX-100, and SDS, respectively. Besides, the different surfactant charges induced different performances to protect Au NPs from agglomeration. Overall, the SDS and CTAB surfactants exhibited higher stability of the Au NPs compared to the Au NPs with TX-100 surfactant.

A Simple Method to Self-Assemble Two-dimensional and Three-dimensional Superlattices of Gold Nanoparticles

2007 ◽  
Vol 1056 ◽  
Author(s):  
Tao Fu ◽  
Hai-Yan Qin ◽  
Wen-Jiang Li ◽  
Sailing He
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gold Nanoparticles ◽  
Particle Dispersion ◽  
Diameter Distribution ◽  
Chloroauric Acid ◽  
Two Dimensional ◽  
Visible Absorption ◽  
Simple Method ◽  
Transmission Electron

ABSTRACTCitrate-capped gold nanoparticles with narrow diameter distribution were prepared by the reduction of chloroauric acid with borohydride. After the gold nanoparticles were transferred to toluene solution through ligand conformation change, close-packed two-dimensional nanocrystal lattices were obtained on transmission electron microscopy (TEM) copper grids by evaporating approximately 10 μL of concentrated particle dispersion. The formation of the thiolate gold nanoparticles was investigated by UV-visible absorption spectroscopy and FTIR spectra. The 2D Fourier transform power spectra of the monolayer confirmed the supperlattices' hexagonal symmetry. Furthermore, long-range-ordered bilayer superlattices, of which the nanoparticles in the top layer piled on the ones in the bottom layer, could also be observed by transmission electron microscopy.

scholarly journals Phytochemical Synthesis and Preliminary Characterization of Silver Nanoparticles Using Hesperidin

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Anish Stephen ◽  
Sankar Seethalakshmi
Keyword(s):  
Electron Microscopy ◽  
Aqueous Solution ◽  
Transmission Electron Microscopy ◽  
Silver Nanoparticles ◽  
Reaction Time ◽  
Silver Nanoparticle ◽  
Size Range ◽  
Transmission Electron ◽  
Vis Spectroscopy

This paper is the first of its kind for development of rapid and ecofriendly method for synthesis of silver nanoparticles from aqueous solution of silver nitrate using the flavonoid “hesperidin” and optimization of the methodology. There is formation of stable spherical silver nanoparticles in the size range of 20–40 nm. Optimization of methodology in terms of concentration of reactants and pH of the reaction mixture reduced the reaction time for silver nanoparticle formation to 2 mins. Silver nanoparticles (AgNPs) were characterized by UV-Vis spectroscopy and transmission electron microscopy (TEM). UV-vis spectroscopy derived spectrum demonstrated a peak of 430 nm which corresponds to the plasmon absorbance of silver nanoparticles. Transmission electron microscopy revealed spherical shaped silver nanoparticles in the size range of 20–40 nm.

Synthesis of Chitosan-Stabilized Gold Nanorod Using Tripolyphosphate

2013 ◽  
Vol 652-654 ◽  
pp. 250-253
Author(s):  
Hua Nan Guan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gold Nanoparticles ◽  
Chemical Synthesis ◽  
Gold Nanorods ◽  
Gold Nanorod ◽  
Gold Salt ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Seed Mediated

An improvement in the previously reported seed-mediated chemical synthesis of gold nanorods (GNRs) is reported. Gold nanoparticles were prepared by reducing gold salt with a polysaccharide, chitosan, in the presence of tripolyphosphate (TPP). The obtained gold nanoparticles were characterized with UV-vis spectroscopy and transmission electron microscopy. The study shows that TPP plays an important role in the formation of GNRs.

scholarly journals Synthesis of Gold Nanoparticles Stabilized in Dextran Solution by Gamma Co-60 Ray Irradiation and Preparation of Gold Nanoparticles/Dextran Powder

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Phan Ha Nu Diem ◽  
Doan Thi Thu Thao ◽  
Dang Van Phu ◽  
Nguyen Ngoc Duy ◽  
Hoang Thi Dong Quy ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gold Nanoparticles ◽  
Spherical Shape ◽  
Powder Form ◽  
X Ray ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Influence Of Ph ◽  
Dextran Solution

Gold nanoparticles (AuNPs) in spherical shape with diameter of 6–35 nm stabilized by dextran were synthesized by γ-irradiation method. The AuNPs were characterized by UV-Vis spectroscopy and transmission electron microscopy. The influence of pH, Au3+ concentration, and dextran concentration on the size of AuNPs was investigated. Results indicated that the smallest AuNPs size (6 nm) and the largest AuNPs size (35 nm) were obtained for pH of 1 mM Au3+/1% dextran solution of 5.5 and 7.5, respectively. The smaller Au3+ concentration favored smaller size and conversely the smaller dextran concentration favored bigger size of AuNPs. AuNPs powders were prepared by spay drying, coagulation, and centrifugation and their sizes were also evaluated. The purity of prepared AuNPs powders was also examined by energy dispersive X-ray (EDX) analysis. Thus, the as-prepared AuNPs stabilized by biocompatible dextran in solution and/or in powder form can be potentially applied in biomedicine and pharmaceutics.

PH Dependence of the Size and Shape of the Gold Nanoparticles Prepared by Macromolecules

2013 ◽  
Vol 634-638 ◽  
pp. 2228-2231
Author(s):  
Chun Rong Wang ◽  
Xian Zai Yan ◽  
Li Li Yu
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gold Nanoparticles ◽  
Electron Diffraction ◽  
Electron Diffraction Pattern ◽  
Ph Dependence ◽  
Gold Nanostructures ◽  
Size And Shape ◽  
Transmission Electron ◽  
Shape Changes

The effect of the pH of the preparing solution on the size and shape of gold nanoparticles was studied in the solution containing soybean peptides or β-cyclodextrin (β-CD) as reducing agent. The resulting gold nanostructures were characterized by transmission electron microscopy (TEM), XRD and UV-vis spectra. Different shape of gold nanoparticles such as nanoplates, networked nanowires and spheres were prepared by changing the pH of solution. Electron diffraction pattern showed that the shape changes from plate or network to sphere as the pH of solution is increasing.

Synthesis and Characterization of Water-Soluble Monolayer-Protected Gold Nanoparticles

2011 ◽  
Vol 415-417 ◽  
pp. 617-620 ◽  
Author(s):  
Yan Su ◽  
Ying Yun Lin ◽  
Yu Li Fu ◽  
Fan Qian ◽  
Xiu Pei Yang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Particle Size ◽  
Gold Nanoparticles ◽  
Average Particle Size ◽  
Water Soluble ◽  
Synthesis And Characterization ◽  
Average Particle ◽  
Transmission Electron

Water-soluble gold nanoparticles (AuNPs) were prepared using 2-mercapto-4-methyl-5- thiazoleacetic acid (MMTA) as a stabilizing agent and sodium borohydride (NaBH4) as a reducing agent. The AuNPs product was analyzed by transmission electron microscopy (TEM), UV-vis absorption spectroscopy and Fourier transform infrared spectroscopy (FTIR). The TEM image shows that the particles were well-dispersed and their average particle size is about 5 nm. The UV-vis absorption and FTIR spectra confirm that the MMTA-AuNPs was stabilized by the carboxylate ions present on the surface of the AuNPs.

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