共查询到20条相似文献,搜索用时 15 毫秒
1.
Satoshi Seino Yu Matsuoka Takashi Nakagawa 《Journal of magnetism and magnetic materials》2009,321(10):1404-1407
Composite gold/iron-oxide nanoparticles were synthesized by a sonochemical process and their surface then modified with polyethylenimine (PEI). The dispersibility of the composite nanoparticles in acidic solution was improved by the PEI modification. The composite nanoparticles specifically adsorbed sulfur-containing amino acids and could be picked up by an external magnetic field. Thus, composite nanoparticles modified with PEI carry both the ability to bond Au-S and to disperse well in buffer solutions. 相似文献
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Takuya Kinoshita Satoshi Seino Yoshiteru Mizukoshi Takashi Nakagawa Takao A. Yamamoto 《Journal of magnetism and magnetic materials》2007
Magnetic composite nanoparticles of gold and iron-oxide synthesized with gamma-rays or ultrasonics were functionalized with thiol-modified oligonucleotides. The amount of oligonucleotides bound to the functionalized nanoparticle probes via hybridization was quantified with fluorescently-labeled target oligonucleotides. Our composite nanoparticles magnetically separated the specific target oligonucleotides without the non-specific adsorption. 相似文献
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Samuel Tehuacanero-Cuapa Etienne F. Brès Rodolfo Palomino-Merino Ramiro García-García 《辐射效应与固体损伤》2013,168(10):838-844
The 200?kV focused electron beam in the convergent beam electron diffraction patterns mode in a transmission electron microscope (TEM) with field emission gun is able to drill holes in gold and silver decahedral nanoparticles. However, although they are done under the same circumstances, the holes are shapeless in the silver and faceted in gold nanoparticles. In addition to this, the holes are closed during their high-resolution TEM observation in both materials. To comment their differences, displacement energy considerations are taken into account as function of the sputtering energy in order to modify the displacement cross-section of the processes. 相似文献
6.
Fatma K. Canitez Mustafa S. Yavuz Ramazan Ozturk 《Journal of nanoparticle research》2011,13(12):7219-7228
In this study, the meso-tetra (p-hydroxyphenyl) porphyrin and meso-tetra (m-hydroxyphenyl) porphyrin were coated on to gold nanoparticles (AuNPs) via thioacetate anchors which easily dissociate to
form S–Au bonds. 4-tert-butyl phenyl thioacetate-AuNPs were prepared and used as a monodentate passivant to control the size of the tetradentate
porphyrin-AuNPs. The porphyrin-coated AuNPs were characterized by UV–Vis, TEM, XRD, and XPS analyses. The tetradentate porphyrin-AuNPs
size is within a range of 5–15 nm in diameter with exotic shapes. The plausible network formation for AuNP@p-TPP-SAc and the capping structure of the AuNP@m-TPP-SAc have been suggested. 相似文献
7.
Composite Au–SnO2 nanoparticles (NPs) are synthesized by nano-soldering of pure Au and SnO2 NPs. The multi-step process involves synthesis of pure Au and SnO2 NPs separately by nanosecond pulse laser ablation of pure gold and pure tin targets in deionized water and post-ablation
laser heating of mixed solution of Au colloidal and SnO2 colloidal to form nanocomposite. Transmission Electron Microscopy (TEM) and High-Resolution Transmission Electron Microscopy
(HRTEM) were used to study the effect of laser irradiation time on morphology of the composite Au–SnO2 NPs. The spherical particles of 4 nm mean size were obtained for 5 min of post-laser heating. Increased mean size and elongated
particles were observed on further laser heating. UV–vis spectra of Au–SnO2 nanocomposites show red shift in the plasmon resonance absorption peak and line shape broadening with respect to pure Au
NPs. The negative binding energy shift of Au 4f7/2 peak observed in X-ray Photoelectron Spectra (XPS) indicates charge transfer in the nano-soldered Au–SnO2 between gold and tin oxide and formation of soldered nanocomposite. 相似文献
8.
Shenfeng LiXiaoying Zhu Wei ZhangGuoming Xie Wenli Feng 《Applied Surface Science》2012,258(7):2802-2807
In this paper, an amperometric electrochemical biosensor for the detection of hydrogen peroxide (H2O2), based on gold nanoparticles (GNPs)/thionine (Thi)/GNPs/multi-walled carbon nanotubes (MWCNTs)-chitosans (Chits) composite film was developed. MWCNTs-Chits homogeneous composite was first dispersed in acetic acid solution and then the GNPs were in situ synthesized at the composite. The mixture was dripped on the glassy carbon electrode (GCE) and then the Thi was deposited by electropolymerization by Au-S or Au-N covalent bond effect and electrostatic adsorption effect as an electron transfer mediator. Finally, the mixture of GNPs and horseradish peroxidase (HRP) was assembled onto the modified electrode by covalent bond. The electrochemical behavior of the modified electrode was investigated by scanning electron microscope, cyclic voltammetry and chronoamperometry. This study introduces the in situ-synthesized GNPs on the other surface of the modified materials in H2O2 detection. The linear response range of the biosensor to H2O2 concentration was from 5 × 10−7 mol L−1 to 1.5 × 10−3 mol L−1 with a detection limit of 3.75 × 10−8 mol L−1 (based on S/N = 3). 相似文献
9.
H. Amrollahi-Bioki 《辐射效应与固体损伤》2013,168(8):715-722
Cross-linking of the polyethylene was performed with a high-energy electron beam. Electron paramagnetic resonance spectroscopy was used to study the lifetime of unpaired electron in the irradiated samples. Time-dependent electrical parameters are investigated for the cross-linked low-density polyethylene. Both dielectric constant and dielectric strength almost remained unchanged, but for short times, the volume resistivity and loss factor increased and decreased, respectively. It is predicted that for lifetime longer than 48 h, the electrical parameters were constant. It is believed that the variation of some electrical properties during time is due to the effects of trapped electrons. 相似文献
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In this paper, we propose a method to generate gold nanoparticles capable of absorbing near infrared light (NIR) radiation
through a photochemical reaction. This approach does not require the use of either surfactants or polymers, reducing the difficulties
that may arise in further chemical modifications for the gold nanoparticles. The gold nanoparticles with either triangular
or hexagonal shapes were generated using the photo-reduction method, mixing hydrogen tetrachloroaurate with sodium oxalate,
a reducing agent, in aqueous solution under illumination of a mercury lamp (λmax = 306 nm) for more than 10 min. The size of the gold nanoparticles varies from 25 to 200 nm, which mainly depends on the duration
of light illumination and the concentration of sodium oxalate. Furthermore, we demonstrate that the presence of the gold nanoparticles
in aqueous solutions can effectively elevate the temperature of the solutions under irradiation of NIR light (808 nm) within
a few minutes. The gold nanoparticles can be potentially used as suitable photothermal agents for hyperthermia. 相似文献
11.
R. Vijayakumar V. Devi K. Adavallan D. Saranya 《Physica E: Low-dimensional Systems and Nanostructures》2011,44(3):665-671
In the present study, we have explored anti-tumor potent Crocus sativus (saffron) as a reducing agent for one pot size controlled green synthesis of gold nanoparticles (AuNps) at ambient conditions. The nanoparticles were characterized using UV–vis, scanning electron microscope (SEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and FTIR analysis. The prepared AuNPs showed surface Plasmon resonance centered at 549 nm with average particle size of 15±5 nm. Stable, spherical and triangular crystalline AuNPs with well-defined dimensions were synthesized using anti-tumor potent Crocus sativus (saffron). Crystalline nature of the nanoparticles is confirmed from the HR-TEM, SAED and SEM images, and XRD patterns. From the FTIR spectra it is found that the biomolecules are responsible for capping in gold nanoparticles. 相似文献
12.
Takashi Ogi Norizoh Saitoh Toshiyuki Nomura Yasuhiro Konishi 《Journal of nanoparticle research》2010,12(7):2531-2539
Biosynthesis of spherical gold nanoparticles and gold nanoplates was achieved at room temperature and pH 2.8 when cell extract
from the metal-reducing bacterium Shewanella algae was used as both a reducing and shape-controlling agent. Cell extract, prepared by sonicating a suspension of S. algae cells, was capable of reducing 1 mol/m3 aqueous AuCl4
− ions into elemental gold within 10 min when H2 gas was provided as an electron donor. The time interval lapsed since the beginning of the bioreductive reaction was found
to be an important factor in controlling the morphology of biogenic gold nanoparticles. After 1 h, there was a large population
of well-dispersed, spherical gold nanoparticles with a mean size of 9.6 nm. Gold nanoplates with an edge length of 100 nm
appeared after 6 h, and 60% of the total nanoparticle population was due to gold nanoplates with an edge length of 100–200 nm
after 24 h. The yield of gold nanoplates prepared with S. algae extract was four times higher than that prepared with resting cells of S. algae. The resulting biogenic gold nanoparticle suspensions showed a large variation in color, ranging from pale pink to purple
due to changes in nanoparticle morphology. 相似文献
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Optical trapping of gold nanoparticles is experimentally demonstrated using radially and azimuthally polarized beams. The transverse optical trapping stiffness of gold nanoparticles is measured. The radially polarized beam exhibits a higher trapping efficiency than the azimuthally polarized beam and the Gaussian beam. The transverse stiffness of particles with different diameters is measured experimentally and calculated via the discrete-dipole approximation method, and good agreement between theory and experiment is found. 相似文献
15.
In order to investigate dynamic change in surface structure, we tried to measure the rocking curve of reflection high-energy electron diffraction (RHEED) by using a quasi-1D convergent beam method, which means a superposition of a hundred RHEED patterns at different glancing angles on one image. After we have checked the experimental accuracy, it is confirmed that the measurement time is shortened to 0.3 s by using this method. We also show an application of this method to a real time observation of surface segregation of B atoms while a highly B-doped Si is annealed. 相似文献
16.
Behavior of metal nanoparticles in the electron beam 总被引:1,自引:0,他引:1
Fabrication and structural observation of In, Pd and Mo nanoparticles deposited on Si(110) substrates were performed in an ultrahigh vacuum field emission transmission electron microscope. In situ and/or dynamic observation of In nanoparticles showed fluctuation of their structures. The smaller particles of size of 3-5 nm showed frequent fluctuation, while the nanoparticles of more than 10 nm in size showed relatively slower fluctuation. The bigger nanoparticles showed coalescence with a weaker beam. Pd nanoparticles of size of 3-5 nm showed structural fluctuation after 10-30 s of electron beam irradiation. Stronger beam irradiation resulted in the dissipation of the nanoparticles probably due to diffusion. Mo nanoparticles of size of 3-5 nm never showed structural fluctuation. Intensive electron beam irradiation resulted in the dissipation of the particles. The difference in structural fluctuation depending on the metal and the beam intensity, and the peculiar coalescence of In nanoparticles are discussed qualitatively. 相似文献
17.
K. Widmann P. Beiersdorfer J.R. Crespo López-Urrutia S.R. Elliott 《Hyperfine Interactions》1997,108(1-3):73-86
The following progress report presents some of the X-ray measurements performed during the last year on the Livermore SuperEBIT
facility. The measurements include: direct observation of the spontaneous emission of the hyperfine transition in ground state
hydrogenlike holmium, 165Ho66+; measurements of the n=2 → 2 transition energies in neonlike thorium, Th80+, through lithiumlike thorium, Th87+, testing the predictions of quantum electrodynamical contributions in high-Z ions down to the 0.4% level; measurements of
the isotope shift of the n=2 → 2 transition energies between lithiumlike through carbonlike uranium, 233U89+⋯ 86+ and 238U89+⋯ 86+, inferring the variation of the mean-square nuclear charge radius; and high-resolution measurements of the Kα radiation of
heliumlike xenon, Xe52+, using a transmission-type crystal spectrometer, resolving for the first time the 1s2p3P1 → 1s21S0 and 1s2s3S1 → 1s21S0 transitions individually.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
18.
One step alkaline synthesis of biocompatible gold nanoparticles using dextrin as capping agent 总被引:1,自引:0,他引:1
Michael J. Anderson Edith Torres-Chavolla Brian A. Castro Evangelyn C. Alocilja 《Journal of nanoparticle research》2011,13(7):2843-2851
Gold nanoparticles (AuNPs) are used in sensing methods as tracers and transducers. The most common AuNP synthesis techniques
utilize citrate under acidic reaction conditions. The synthesis described in this article generates glyco-AuNPs under mild
alkaline conditions providing a “greener” alternative to Brust and Turkevich methodologies. This biologically compatible one-step
technique uses dextrin as a capping agent and sodium carbonate as the reducing agent for chloroauric acid. The generated particles
were relatively mono-dispersed and water soluble with a range of controllable mean diameters from 5.9 to 16.8 ± 1.6 nm. The
produced AuNPs were stable in water for more than 6 months stored at room temperature (21 °C) in generation solution without
protection from light. This article shows the effect of temperature, pH, and dextrin concentration on the synthesis procedure
and AuNP diameter. These factors were found to control the reaction speed. The produced glyco-AuNPs were successfully functionalized
with DNA oligonucleotides, and the functionalization efficiency was similar to citrate-generated AuNPs. The alkaline synthesis
allows future exploration of simultaneous synthesis and functionalization procedures, which could significantly reduce the
time of current ligand exchange methodologies. 相似文献
19.
The ability to control the assembly of nanoparticle building blocks is critically important for the development of new materials
and devices. The properties and functions of nanomaterials are not only dependent on the size and properties of individual
particles, but also the interparticle distance and interactions. In order to control the structures of nanoassemblies, it
is important to first achieve a precise control on the chemical functionality of nanoparticle building blocks. This review
discusses three methods that have been reported recently for the preparation of monofunctional gold nanoparticles, i.e., nanoparticles
with a single chemical functional group attached to each particle. The advantages and disadvantages of the three methods are
discussed and compared. With a single functional group attached to the surface, one can treat such nanoparticles as molecular
building blocks to react with other molecules or nanoparticles. In other words, by using appropriate chemical reactions, nanoparticles
can be linked together into nanoassemblies and materials by covalent bonds, similar to the total chemical synthesis of complicated
organic compounds from smaller molecular units. An example of using this approach for the synthesis of nanoparticle/polymer
hybrid materials with optical limiting properties is presented. Other potential applications and advantages of covalent bond-based
nanoarchitectures vs. non-covalent interaction-based supramolecular self-assemblies are also discussed briefly in this review. 相似文献
20.
We have investigated the crystal structure of nanosized iron-oxide by X-ray diffraction (XRD), extended X-ray absorption fine
structure measurements at the iron K-edge as well as by transmission electron microscopy (TEM). Iron-oxide nanoparticles were
produced by thermal treatment of horse spleen ferritin molecules. The structure of these particles was compared to α-Fe2O3 and γ-Fe2O3 nanopowder references. The thermal treatment of a submonolayer film of ferritin molecules results in pure γ-Fe2O3 nanoparticles, while for films above a certain thickness α-Fe2O3 and γ-Fe2O3 coexist, exhibiting two different crystallite sizes. TEM shows a characteristic particle diameter of ~7 nm for γ-Fe2O3 resulting from thermal treatment of monolayers, consistent with the crystallite size of the γ-phase as obtained from XRD
measurements on multi-layered samples. XRD shows the α-Fe2O3 phase to be characterized by a crystallite size of ~34 nm. 相似文献