Controlled Synthesis and Characterization of Co-Au Core-shell Nanoparticles

2005 ◽  
Vol 877 ◽  
Author(s):  
Yuping Bao ◽  
Hector Calderon ◽  
Kannan M. Krishnan
Keyword(s):  
Core Shell ◽  
Gold Compound ◽  
Contrast Imaging ◽  
Shell Nanoparticles ◽  
Transmission Electron ◽  
Wide Range ◽  
High Resolution Tem ◽  
Core Shell Nanoparticles ◽  
Z Contrast ◽  
First Time

AbstractCo-Au Core-shell nanoparticles are synthesized by slowly reducing an organo-gold compound on pre-made cobalt seeds with a weak reducer at mild condition. For the first time, these coreshell nanoparticles are generated in non-polar solvent in a controlled manner. The formation theory of core-shell structure, especially the seed size effect, is addressed as well. These coreshell structures are confirmed with a wide range of transmission electron microscopy (TEM) methods, which includes routine TEM images, high resolution TEM, and z-contrast imaging.

scholarly journals Synthesis and Advanced Characterization of Polymer-Protein Core-Shell Nanoparticles

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 730
Author(s):  
Erik Sarnello ◽  
Tao Li
Keyword(s):  
Particle Size ◽  
Small Angle ◽  
Core Shell ◽  
Assembly Process ◽  
Shell Nanoparticles ◽  
X Ray ◽  
X Ray Scattering ◽  
Wide Range ◽  
Core Shell Nanoparticles ◽  
Ray Scattering

Enzyme immobilization techniques are widely researched due to their wide range of applications. Polymer–protein core–shell nanoparticles (CSNPs) have emerged as a promising technique for enzyme/protein immobilization via a self-assembly process. Based on the desired application, different sizes and distribution of the polymer–protein CSNPs may be required. This work systematically studies the assembly process of poly(4-vinyl pyridine) and bovine serum albumin CSNPs. Average particle size was controlled by varying the concentrations of each reagent. Particle size and size distributions were monitored by dynamic light scattering, ultra-small-angle X-ray scattering, small-angle X-ray scattering and transmission electron microscopy. Results showed a wide range of CSNPs could be assembled ranging from an average radius as small as 52.3 nm, to particles above 1 µm by adjusting reagent concentrations. In situ X-ray scattering techniques monitored particle assembly as a function of time showing the initial particle growth followed by a decrease in particle size as they reach equilibrium. The results outline a general strategy that can be applied to other CSNP systems to better control particle size and distribution for various applications.

Monodisperse Fe3O4/Fe Core/Shell Nanoparticles with Enhanced Magnetic Property

2011 ◽  
Vol 306-307 ◽  
pp. 410-415
Author(s):  
Li Sun ◽  
Fu Tian Liu ◽  
Qi Hui Jiang ◽  
Xiu Xiu Chen ◽  
Ping Yang
Keyword(s):  
Average Diameter ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Shell Nanoparticles ◽  
X Ray ◽  
Transmission Electron ◽  
Shell Particles ◽  
Core Shell Nanoparticles

Core/shell type nanoparticles with an average diameter of 20nm were synthesized by chemical precipitation method. Firstly, Monodisperse Fe3O4 nanoparticles were synthesized by solvethermal method. FeSO4ž7H2O and NaBH4 were respectively dissolved in distilled water, then moderated Fe3O4 particles and surfactant(PVP) were ultrasonic dispersed into the FeSO4ž7H2O solution. The resulting solution was stirred 2 h at room temperature. Fe could be deposited on the surface of monodispersed Fe3O4 nanoparticles to form core-shell particles. The particles were characterized by using various experimental techniques, such as transmission electron microscopy (TEM), X-ray diffraction (XRD), AGM and DTA. The results suggest that the saturation magnetization of the nanocomposites is 100 emu/g. The composition of the samples show monodisperse and the sides of the core/shell nanoparticles are 20-30nm. It is noted that the formation of Fe3O4/Fe nanocomposites magnetite nanoparticles possess superparamagnetic property.

The Preparation and Characteristic of Superparamagnetic Core/Shell Nanoparticles

2013 ◽  
Vol 274 ◽  
pp. 432-435
Author(s):  
Hong Xia Shen ◽  
Zheng Zhi Yin ◽  
Qiong Cheng
Keyword(s):  
Biomedical Applications ◽  
Superparamagnetic Nanoparticles ◽  
Bioactive Molecules ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
X Ray ◽  
Transmission Electron ◽  
Vibration Sample Magnetometer ◽  
Diffraction Patterns ◽  
Core Shell Nanoparticles

Superparamagnetic core/shell nanoparticles have been prepared successfully by the reduction of Au3+ onto the surface of superparamagnetic nanoparticles. The core/shell nanoparticles were characterized by Transmission electron microscopy (TEM), X-ray powder diffraction patterns (XRD), UV–vis spectrophotometer, Vibration Sample Magnetometer(VSM) and micro-confocal Raman system. The results revealed that the prepared core/shell nanoparticles were covered by Au shell. These superparamagnetic nanoparticles can be highly sensitively detected and afford new opportunities for biomedical applications through chemical bonding of bioactive molecules with the Au shell of nanoparticles.

Characterization of a Porous Carbon Material Functionalized with Cobalt-Oxide/Cobalt Core-Shell Nanoparticles for Lithium Ion Battery Electrodes

MRS Advances ◽  
2016 ◽  
Vol 1 (15) ◽  
pp. 1061-1066
Author(s):  
Dalaver H. Anjum ◽  
Shahid Rasul ◽  
Manuel A. Roldan-Gutierrez ◽  
Pedro M. F. J. Costa
Keyword(s):  
Lithium Ion Battery ◽  
Cobalt Oxide ◽  
Lithium Ion ◽  
Oxide Shell ◽  
Porous Carbon Material ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Transmission Electron ◽  
Core Shell Nanoparticles ◽  
Type Lattice

ABSTRACTA nanoporous carbon (C) material, functionalized with Cobalt-Oxide/Cobalt (CoO/Co) core-shell nanoparticles (NPs), was structurally and chemically characterized with transmission electron microcopy (TEM) while its electrochemical response for Lithium ion battery (LIB) applications was evaluated as well. The results herein show that the nanoporous C material was uniformly functionalized with the CoO/Co core-shell NPs. Further the NPs were crystalline with fcc-type lattice on the Co2+ oxide shell and hcp-type core of metallic Co0. The electrochemical study was carried out by using galvanostatic charge/discharge cycling at a current density of 1000 mA g−1. The potential of this hybrid material for LIB applications was confirmed and it is attributed to the successful dispersion of the Co2+/ Co0 NPs in the C support.

Synthesis of Co@Au Core-Shell Nanoparticles in Non-Aqueous Solution and their Characterization

2004 ◽  
Vol 818 ◽  
Author(s):  
Zhihui Ban ◽  
C. J. O'Connor
Keyword(s):  
Aqueous Solution ◽  
Quantum Interference ◽  
Au Nanoparticles ◽  
Magnetic Measurements ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Shell Nanoparticles ◽  
Transmission Electron ◽  
Average Size ◽  
Core Shell Nanoparticles

AbstractA homogeneous non-aqueous solution reactions method has been developed to prepare gold-coated cobalt (Co@Au) nanoparticles. After the sample was washed with 8% HCl, XRD (X-Ray Diffraction), TEM (transmission electron microscopy), and magnetic measurements SQUID (Superconducting Quantum Interference Device) are utilized to characterize the nanocomposites. XRD shows the pattern of sample, which is responding to gold and cobalt, no cobalt oxide was found. TEM results show that the average size of Co@Au nanoparticles is about 10 nm and we can find core-shell structure of the sample. SQUID results show that the particles are ferromagnetic materials at 300K. So the gold- coated cobalt nanoparticles (Co@Au) can be successfully prepared by the homogeneous nonaqueous approach. This kind of core-shell materials is stable in acid condition, which would give many opportunities for bio- application.

scholarly journals Process Optimization for the Synthesis of Silver (AgNPs), Iron Oxide (α-Fe2O3NPs) and Core-Shell (Ag-Fe2O3CNPs) Nanoparticles Using the Aqueous Extract of Alstonia Scholaris: A Greener Approach

2018 ◽  
Vol 12 (1) ◽  
pp. 29-39 ◽  
Author(s):  
Navinchandra G. Shimpi ◽  
Mujahid Khan ◽  
Sharda Shirole ◽  
Shriram Sonawane
Keyword(s):  
Fourier Transform ◽  
Iron Oxide ◽  
Aqueous Extract ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Alstonia Scholaris ◽  
Transmission Electron ◽  
Infra Red ◽  
High Level ◽  
Core Shell Nanoparticles

Objective:The present study is deals with the green synthesis of silver (AgNPs), iron oxide (α-Fe2O3NPs) and core-shell (Ag-α-Fe2O3CNPs) nanoparticles using the aqueous extract ofAlstonia scholariswithout any catalyst, template or surfactant or any intermediate under ultrasound cavitation technique. The purpose was to facilitate the high level of dispersion with increase in rate of reaction. Further AgNPs and α-Fe2O3NPs were used to synthesis Ag-Fe2O3CNPs in aqueous extract ofAlstonia scholarisunder controlled ultrasound cavitation technique.Methods:The size of AgNPs and Ag-Fe2O3CNPs can be tuned by optimizing various reaction parameters. UV-visible, X-ray diffraction spectroscopy (XRD), Transmission electron microscopy (TEM), Field emission scanning electron microscope (FE-SEM) and Fourier transform infra-red spectroscopy has been used for the characterization of silver and core shell Ag@Fe2O3nanoparticles. TEM images clearly show the formation of core shell nanoparticles with spherical morphology.Result:Fourier transform infra-red spectroscopy analysis revealed that carbohydrate, polyphenols, and protein molecules were involved in the synthesis and capping of silver, iron oxide and Ag@Fe2O3CNPs.

scholarly journals Conjugation of oligo-His peptides to magnetic γ-Fe2O3@SiO2 core-shell nanoparticles promotes their access to the cytosol

2021 ◽  
Author(s):  
Mathilde Le Jeune ◽  
Emilie Secret ◽  
Michaël Trichet ◽  
Aude Michel ◽  
Delphine Ravault ◽  
...  
Keyword(s):  
Cell Penetrating Peptides ◽  
Endosomal Escape ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Heating Efficiency ◽  
Multiple Substrates ◽  
Transmission Electron ◽  
Cell Penetrating ◽  
Calcein Leakage ◽  
Core Shell Nanoparticles

The endosomal entrapment of functional nanoparticles is a severe limitation to their use for biomedical applications. In the case of magnetic nanoparticles (MNPs), this entrapment leads to poor heating efficiency for magnetic hyperthermia and suppresses the possibility to manipulate them in the cytosol. Current strategies to limit their entrapment are based on their functionalization with cell-penetrating peptides in order to promote their translocation directly across the cell membrane or their endosomal escape. However, these strategies suffer from potential release of free peptides in cell and to the best of our knowledge there is currently a lack of effective methods for the cytosolic delivery of MNPs after incubation with cells. Herein, we report the conjugation of fluorescently labelled cationic peptides to γ-Fe2O3@SiO2 core-shell nanoparticles by click chemistry to improve MNP access to the cytosol. We compare the effect of Arg9 and His4 peptides. On one hand, Arg9 is a classical cell-penetrating peptide, able to enter cells by direct translocation and on the other hand, it has been demonstrated that sequences rich in histidine residues promote endosomal escape, most probably by the proton sponge effect. The methodology developed allows to have a high co-localization of the peptides and core-shell nanoparticles in cells and to attest that the grafting onto nanoparticles of peptides rich in histidine promotes NP access to the cytosol. The endosomal escape was confirmed by a calcein leakage assay and by ultrastructural analysis in transmission electron microscopy. No toxicity of the nanoparticles functionalized with peptides was found. We show that our conjugation strategy is compatible with the addition of multiple substrates and can thus be used for the delivery of cytoplasm-targeted therapeutics.

Synthesis and Characterization of Fe/Nd2O3 Core–Shell Nanoparticles by Hydrogen Plasma-Metal Reaction

2006 ◽  
Vol 6 (3) ◽  
pp. 743-747 ◽  
Author(s):  
Tong Liu ◽  
Shicheng Zhang ◽  
Xingguo Li
Keyword(s):  
Hydrogen Plasma ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
X Ray ◽  
Nanoparticle Surface ◽  
Transmission Electron ◽  
Potential Applications ◽  
Catalytic Fields ◽  
Core Shell Nanoparticles

Fe/Nd2O3 core–shell nanoparticles (CSNs) with a mean diameter of 35 nm were produced successfully by using hydrogen plasma-metal reaction (HPMR) method. This core–shell structure was confirmed by high resolution transmission electron microscopy (HRTEM), energy dispersion X-ray spectroscopy (EDS), X-ray photoelectron spectral (XPS), and induction-coupled plasma (ICP) spectroscopy. The magnetic properties were measured by vibrating sample magnetometer (VSM). It was found that the mole ratio of Nd to Fe on the nanoparticle surface is 1.2:1, about 7 times of that of the whole nanoparticle. The saturation magnetization Ms and remanence Mr of Fe/Nd2O3 nanoparticles decrease prominently from Fe nanoparticles, whereas the coercivity HC drops only less than 5% of Fe nanoparticle. These CSNs have potential applications in magnetic and catalytic fields.

Preparation and Characterization of Nickel(Ni)-Silver(Ag) Core-Shell Nanoparticles for Conductive Pastes

2012 ◽  
Vol 531 ◽  
pp. 211-214 ◽  
Author(s):  
Jun Jie Jing ◽  
Ji Min Xie ◽  
Hui Ru Qin ◽  
Wen Hua Li ◽  
Ming Mei Zhang
Keyword(s):  
Electron Microscopy ◽  
Inductively Coupled Plasma ◽  
Water Solution ◽  
Average Diameter ◽  
Core Shell ◽  
Ni Nanoparticles ◽  
Shell Nanoparticles ◽  
Inductively Coupled ◽  
Transmission Electron ◽  
Core Shell Nanoparticles

Nickel(Ni)-silver(Ag) core-shell nanoparticles with different shell thickness were synthesized with Ni nanoparticles by liquid phase reduction technique form water solution. The product was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and inductively coupled plasma spectroscopy (ICP). The results showed that the Ni nanoparticles are in sphere shape and the average diameter is 104nm , the nickel(Ni)-silver(Ag) core-shell nanoparticles has good crystallinity and the thinkness of Ag nanoshells could be effectively controlled by changing the concentration of silver nitrate. The product can be used for nickel-based conductive paste preparation because of the surface character of Ag and the magnetic property of Ni

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