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1.
Stable hydroxyapatite (HAP) nanoparticles system was synthesized from Ca(H(2)PO(4))(2) aqueous solution and saturated Ca(OH)(2) aqueous solution by an improved precipitation method. This method was reformed through using ultrasound irradiation as assistant technology due to its unique chemical reaction effects and adding glycosaminoglycans (GAGs) as regulation additive due to its strong interaction with HAP. The products were characterized by Malvern Zetasizer 3000HS Analysis system, TEM and ED. The size distribution and zeta potential of HAP nanoparticles were influenced by the concentration of GAGs. With the GAGs concentration of 0.35g/L, the better excellent HAP nanoparticle system could be obtained with the number-averaged particle size of 22.2nm in 84.5% area and 54.6nm in 15.5% area between 18.1nm and 117.4nm and the zeta potential of -60.9mV. In the presence of GAGs, the particle size and size distribution are little sensitive to the ultrasound irradiation (UI) time. With the increasing of UI time from 0.5h to 3h and 5h, the particle size increased a little and the crystallinity was improved. GAGs inhibited HAP crystal growth and stabilized HAP nanoparticles. Based on the TEM observation and size distribution determination of HAP nanoparticles, the possible formation mechanism of HAP nanoparticles stabilized by GAGs under UI was discussed. 相似文献
2.
Highly stable and spherical silver nanoparticles, stabilized by methoxycarbonyl-terminated hyperbranched poly(amine-ester)
(HPAE-COOCH3), were synthesized in water with reducing AgNO3/HPAE-COOCH3 using two methods, viz. NaBH4 and ultraviolet irradiation. HPAE-COOCH3 was found to play a key role in the formation of nanoparticles. UV–visible absorption, Transmission electron microscopic
(TEM), and Fourier transform infrared spectroscopy (FT-IR) had been used to study the structure and characterization of the
silver nanoparticles. The absorption peaks of the silver nanoparticles appear at ~420 nm in UV–visible absorption spectra;
average particle size reduced by NaBH4 is ~30 nm, which is ~10 and ~15 nm, respectively, when ultraviolet irradiation time is 12 and 24 h. FT-IR spectra confirm
that there is strong interaction between silver nanoparticles and HPAE-COOCH3. And silver nanoparticles/HPAE-COOCH3 aqueous solution can keep stable for more than 3 months. 相似文献
3.
Doohyun Kim Yujin Hwang Seong Ir Cheong Jae Keun Lee Daeseung Hong Seongyong Moon Jung Eun Lee Soo H. Kim 《Journal of nanoparticle research》2008,10(7):1121-1128
We present a one-step electrochemical method to produce water-based stable carbon nano colloid (CNC) without adding any surfactants
at the room temperature. The physical, chemical, and thermal properties of CNC prepared were characterized by using various
techniques, such as particle size analyzer, zeta potential meter, TEM, XRD, FT-IR, turbidity meter, viscometer, and transient
hot-wire method. The average primary size of the suspended spherical-shaped nanoparticles in the CNC was found to be ∼15 nm
in diameter. The thermal conductivity of CNC compared with that of water was observed to increase up to ∼14% with the CNC
concentration of ∼4.2 wt%. The CNC prepared in this study was considerably stable over the period of 600 h. With the assistance
of FT-IR spectroscopy analysis, we confirmed the presence of carboxyl group (i.e., O–H stretching (3,458 cm−1) and C=O stretching (1,712 cm−1)) formed in the outer atomic layer of carbon nanoparticles, which (i) made the carbon particles hydrophilic and (ii) prevented
the aggregation among primary nanoparticles by increasing the magnitude of zeta potential over the long period. 相似文献
4.
In this paper, data concerning the effect of pH on the morphology of Ag–TiO2 nanocomposite during photodeposition of Ag on TiO2 nanoparticles is reported. TiO2 nanoparticles prepared by sol–gel method were coated with Ag by photodeposition from an aqueous solution of AgNO3 at various pH levels ranging from 1 to 10 in a titania sol, under UV light. The as-prepared nanocomposite particles were
characterized by UV–vis absorption spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and N2 adsorption/desorption method at liquid nitrogen temperature (−196 °C) from Brunauer–Emmett–Teller (BET) measurements. It
is shown that at a Ag loading of 1.25 wt.% on TiO2, a high-surface area nanocomposite morphology corresponding to an average of one Ag nanoparticle per titania nanoparticle
was achieved. The diameter of the titania crystallites/particles were in the range of 10–20 nm while the size of Ag particles
attached to the larger titania particles were 3 ± 1 nm as deduced from crystallite size by XRD and particle size by TEM. Ag
recovery by photo harvesting from the solution was nearly 100%. TEM micrographs revealed that Ag-coated TiO2 nanoparticles showed a sharp increase in the degree of agglomeration for nanocomposites prepared at basic pH values, with
a corresponding sharp decrease in BET surface area especially at pH > 9. The BET surface area of the Ag–TiO2 nanoparticles was nearly constant at around a value of 140 m2 g−1 at all pH from 1–8 with an anomalous maximum of 164 m2 g−1 when prepared from a sol at pH of 4, and a sharp decrease to 78 m2 g−1 at pH of 10. 相似文献
5.
Zero valent iron nanoparticles are of increasing interest in clean water treatment applications due to their reactivity toward
organic contaminants and their potential to degrade a variety of compounds. This study focuses on the effect of organophosphate
stabilizers on nanoparticle characteristics, including particle size distribution and zeta potential, when the stabilizer
is present during nanoparticle synthesis. Particle size distributions from DLS were obtained as a function of stabilizer type
and iron precursor (FeSO4·7H2O or FeCl3), and nanoparticles from 2 to 200 nm were produced. Three different organophosphate stabilizer compounds were compared in
their ability to control nanoparticle size, and the size distributions obtained for particle volume demonstrated differences
caused by the three stabilizers. A range of stabilizer-to-iron (0.05–0.9) and borohydride-to-iron (0.5–8) molar ratios were
tested to determine the effect of concentration on nanoparticle size distribution and zeta potential. The combination of ferrous
sulfate and ATMP or DTPMP phosphonate stabilizer produced stabilized nanoparticle suspensions, and the stabilizers tested
resulted in varying particle size distributions. In general, higher stabilizer concentrations resulted in smaller nanoparticles,
and excess borohydride did not decrease nanoparticle size. Zeta potential measurements were largely consistent with particle
size distribution data and indicated the stability of the suspensions. Probe sonication, as a nanoparticle resuspension method,
was minimally successful in several different organic solvents. 相似文献
6.
In this work, the fungus Penicillium was used for rapid extra-/intracellular biosynthesis of gold nanoparticles. AuCl4
− ions reacted with the cell filtrate of Penicillium sp. resulting in extracellular biosynthesis of gold nanoparticles within 1 min. Intracellular biosynthesis of gold nanoparticles
was obtained by incubating AuCl4
− solution with fungal biomass for 8 h. The gold nanoparticles were characterized by means of visual observation, UV–Vis absorption
spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive
X-ray spectroscopy (EDX). The extracellular nanoparticles exhibited maximum absorbance at 545 nm in UV–Vis spectroscopy. The
XRD spectrum showed Bragg reflections corresponding to the gold nanocrystals. TEM exhibited the formed spherical gold nanoparticles
in the size range from 30 to 50 nm with an average size of 45 nm. SEM and TEM revealed that the intracellular gold nanoparticles
were well dispersed on the cell wall and within the cell, and they are mostly spherical in shape with an average diameter
of 50 nm. The presence of gold was confirmed by EDX analysis. 相似文献
7.
Single domain magnetic CoFe2O4 nanoparticles with spinel structure were prepared by the coprecipitation method. Particles with size of 16, 20, 40 and 60 nm were synthesized by sintering the precursor at 500, 600, 800 and 900 °C, respectively. The magnetic hysteresis measurement of CoFe2O4 particles showed that particles were single domain particles with similar saturation magnetization (∼300 emu/cm3) at room temperature. The zeta potential study of suspensions (CoFe2O4-acetylacetone system) with various particle sizes showed the suspension systems had similar zeta potential values (∼40 mV). The effects of magnetic particle size on the suspension stability characterized by electrophoretic deposition yields and sediment volumes were studied. The suspension stability decreased with an increase in particle size and a flocculation threshold of particle radius a was found at 30 nm. A suspension stability theory approaching to the phenomenon was established. The theory based on the DLVO theory was developed by introducing an extra magnetic interaction force. Dormann model was adopted, in which the magnetic interactions of two spherical nanoparticles were investigated in terms of dipole-dipole interactions. Compared to DLVO, suspension's physical parameters not only zeta potential ζ and the Debye length 1/κ, but also particles' radius a brought about stable to flocculation transition in the theory. 相似文献
8.
Metallic gold nanoparticles have been synthesized by the reduction of chloroaurate anions [AuCl4]− solution with hydrazine in the aqueous starch and ethylene glycol solution at room temperature and at atmospheric pressure.
The characterization of synthesized gold nanoparticles by UV–vis spectroscopy, high resolution transmission electron microscopy
(HRTEM), electron diffraction analysis, X-ray diffraction (XRD), and X-rays photoelectron spectroscopy (XPS) indicate that
average size of pure gold nanoparticles is 3.5 nm, they are spherical in shape and are pure metallic gold. The concentration
effects of [AuCl4]− anions, starch, ethylene glycol, and hydrazine, on particle size, were investigated, and the stabilization mechanism of Au
nanoparticles by starch polymer molecules was also studied by FT-IR and thermogravimetric analysis (TGA). FT-IR and TGA analysis
shows that hydroxyl groups of starch are responsible of capping and stabilizing gold nanoparticles. The UV–vis spectrum of
these samples shows that there is blue shift in surface plasmon resonance peak with decrease in particle size due to the quantum
confinement effect, a supporting evidence of formation of gold nanoparticles and this shift remains stable even after 3 months. 相似文献
9.
O. Kaman P. Veverka Z. Jirák M. Maryško K. Knížek M. Veverka P. Kašpar M. Burian V. Šepelák E. Pollert 《Journal of nanoparticle research》2011,13(3):1237-1252
The magnetic nanoparticles of La0.75Sr0.25MnO3 perovskite manganite with a controlled size were prepared via sol–gel procedure, followed by thermal treatment and subsequent
mechanical processing of the resulting raw product. The prepared materials were structurally studied by the XRD and TEM methods
and probed by DC magnetic measurements. The nanoparticles of the mean crystallite sizes 11–40 nm exhibit T
C in the range of ≈310–347 K and the sample possessing 20-nm crystallites was identified as the most suitable for hyperthermia
experiments. In order to obtain a colloidally stable suspension and prevent toxic effects, the selected magnetic cores were
further encapsulated into silica shell using tetraethoxysilane. The detailed magnetic studies were focused on the comparison
of the raw product, the bare nanoparticles after mechanical processing and the silica-coated nanoparticles, dealing also with
effects of size distribution and magnetic interactions. The heating experiments were carried out in an AC field of frequencies
100 kHz–1 MHz and amplitude 3.0–8.9 kA m−1 on water dispersions of the samples, and the generated heat was deduced from their warming rate taking into account experimentally
determined thermal losses into surroundings. The experiments demonstrate that the heating efficiency of the coated nanoparticles
is generally higher than that of the bare magnetic cores. It is also shown that the aggregation of the bare nanoparticles
increases heating efficiency at least in a certain concentration range. 相似文献
10.
Superparamagnetic iron oxide nanoparticles are used in diverse applications, including optical magnetic recording, catalysts,
gas sensors, targeted drug delivery, magnetic resonance imaging, and hyperthermic malignant cell therapy. Combustion synthesis
of nanoparticles has significant advantages, including improved nanoparticle property control and commercial production rate
capability with minimal post-processing. In the current study, superparamagnetic iron oxide nanoparticles were produced by
flame synthesis using a coflow flame. The effect of flame configuration (diffusion and inverse diffusion), flame temperature,
and additive loading on the final iron oxide nanoparticle morphology, elemental composition, and particle size were analyzed
by transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), energy dispersive spectroscopy (EDS), and Raman spectroscopy.
The synthesized nanoparticles were primarily composed of two well known forms of iron oxide, namely hematite αFe2O3 and magnetite Fe3O4. We found that the synthesized nanoparticles were smaller (6–12 nm) for an inverse diffusion flame as compared to a diffusion
flame configuration (50–60 nm) when CH4, O2, Ar, and N2 gas flow rates were kept constant. In order to investigate the effect of flame temperature, CH4, O2, Ar gas flow rates were kept constant, and N2 gas was added as a coolant to the system. TEM analysis of iron oxide nanoparticles synthesized using an inverse diffusion
flame configuration with N2 cooling demonstrated that particles no larger than 50–60 nm in diameter can be grown, indicating that nanoparticles did not
coalesce in the cooler flame. Raman spectroscopy showed that these nanoparticles were primarily magnetite, as opposed to the
primarily hematite nanoparticles produced in the hot flame configuration. In order to understand the effect of additive loading
on iron oxide nanoparticle morphology, an Ar stream carrying titanium-tetra-isopropoxide (TTIP) was flowed through the outer
annulus along with the CH4 in the inverse diffusion flame configuration. When particles were synthesized in the presence of the TTIP additive, larger
monodispersed individual particles (50–90 nm) were synthesized as observed by TEM. In this article, we show that iron oxide
nanoparticles of varied morphology, composition, and size can be synthesized and controlled by varying flame configuration,
flame temperature, and additive loading. 相似文献
11.
Maleic anhydride was grafted by long-chain alcohols (1-hexadecanol, 1-octadecanol) to amphiphilic mono-L cis-butene dicarboxylates (L = hexadecyl, octadecyl), i.e., MAH, MAO, respectively. Subsequently, corresponding amphiphilic cerium
complexes with these two mono-L cis-butene dicarboxylate ligands (Ce(L')3, L'= MAH, MAO) were synthesized and behaved as the precursors to prepare CeO2 nanoparticles for both of which can form nanosized micelle-like aggregates by special self-assembly in the wet chemical process.
The nanoparticles were further characterized by Fourier transform-infrared spectroscopy (FTIR), Diffuse reflectance ultraviolet-visible
spectra (DRUVS), scanning electron microscope (SEM), transmission electron microscope (TEM), and x-ray diffraction (XRD).
Both the CeO2 nanoparticles are in a cubic fluorite structure and present regular and well-dispersion club-like morphology with average
particle size in the range of 40–70 nm. Besides, the strong ultraviolet–visible absorption for these CeO2 nanoparticles can be found at the long-wavelength ultraviolet to visible region of 200–500 nm. 相似文献
12.
The Fe3O4/polythiophene nanoparticles, possessing core–shell structure, were prepared by two-step method. In the first step, the Fe3O4 particles were synthesized via co-precipitation of FeCl3 and FeSO4, using the NH3·H2O and N2H4·H2O as precipitant system. In the second step, the thiophene adsorbed and polymerized on the surface of the Fe3O4 in the solvent of chloroform. Raman, FTIR, EDS, XRD, TEM, Zeta potential measurement and TG-SDTA were employed to characterize
the composition and structure of the products. The results showed that the Fe3O4/polythiophene nanoparticles were successfully synthesized with good dispersion and stable core–shell structure, provided
with average particle size of approximately 20 nm, in which the diameter of Fe3O4 core was approximately 14 nm and the thickness of polythiophene shell was approximately 3–4 nm. Then, the nanoparticles were
added into alkyd varnish to prepare a composite coating. The neutral salt spray test, paraffin control test and mechanical
test were carried out to identify the properties of the composite coating. It was found that the composite coating had good
performances of anticorrosion and paraffin controlling when the mass fraction of the nanoparticles was 0.8–1 wt% in alkyd
varnish. As a multifunctional material, the Fe3O4/polythiophene nanoparticles can be used in the internal coating of pipeline and have great potential application in crude
oil pipeline transportation. 相似文献
13.
Jeremiah D. Keyes Robert J. Hilton Jeffrey Farrer Richard K. Watt 《Journal of nanoparticle research》2011,13(6):2563-2575
The ferrihydrite mineral core of ferritin is a semi-conductor capable of catalyzing oxidation/reduction reactions. This report
shows that ferritin can photoreduce AuCl4
− to form gold nanoparticles (AuNPs). An important goal was to identify innocent reaction conditions that prevented formation
of AuNPs unless the sample was illuminated in the presence of ferritin. TRIS buffer satisfied this requirement and produced
AuNPs with spherical morphology with diameters of 5.7 ± 1.6 nm and a surface plasmon resonance (SPR) peak at 530 nm. Size-exclusion
chromatography of the AuNP–ferritin reaction mixture produced two fractions containing both ferritin and AuNPs. TEM analysis
of the fraction close to where native ferritin normally elutes showed that AuNPs form inside ferritin. The other peak eluted
at a volume indicating a particle size much larger than ferritin. TEM analysis revealed AuNPs adjacent to ferritin molecules
suggesting that a dimeric ferritin–AuNP species forms. We propose that the ferritin protein shell acts as a nucleation site
for AuNP formation leading to the AuNP-ferritin dimeric species. Ferrihydrite nanoparticles (~10 nm diameter) were unable
to produce soluble AuNPs under identical conditions unless apo ferritin was present indicating that the ferritin protein shell
was essential for stabilizing AuNPs in aqueous solution. 相似文献
14.
Vineet Panchal Manoj Neergat Upendra Bhandarkar 《Journal of nanoparticle research》2011,13(9):3825-3833
Core–shell nanoparticles coated with carbon have been synthesized in a single chamber using a continuous and entirely low-pressure
plasma-based process. Nanoparticles are formed in an argon plasma using iron pentacarbonyl Fe(CO)5 as a precursor. These particles are trapped in a pure argon plasma by shutting off the precursor and then coated with carbon
by passing acetylene along with argon as the main background gas. Characterization of the particles was carried out using
TEM for morphology, XPS for elemental composition and PPMS for magnetic properties. Iron nanoparticles obtained were a mixture
of FeO and Fe3O4. TEM analysis shows an average size of 7–14 nm for uncoated particles and 15–24 nm for coated particles. The effect of the
carbon coating on magnetic properties of the nanoparticles is studied in detail. 相似文献
15.
Nalenthiran Pugazhenthiran Sambandam Anandan Govindarajan Kathiravan Nyayiru Kannaian Udaya Prakash Simon Crawford Muthupandian Ashokkumar 《Journal of nanoparticle research》2009,11(7):1811-1815
A silver resistant Bacillus sp. was isolated through exposure of an aqueous AgNO3 solution to the atmosphere. Silver nanoparticles were synthesized using these airborne bacteria (Bacillus sp.). Transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) analyses confirmed that silver nanoparticles
of 5–15 nm in size were deposited in the periplasmic space of the bacterial cells; a preferable cell surface location for
the easy recovery of biogenic nanoparticles. 相似文献
16.
Gang Chen Wenhua Yu Dileep Singh David Cookson Jules Routbort 《Journal of nanoparticle research》2008,10(7):1109-1114
Knowledge of the size and distribution of nanoparticles in solution is critical to understanding the observed enhancements
in thermal conductivity and heat transfer of nanofluids. We have applied small-angle X-ray scattering (SAXS) to the characterization
of SiO2 nanoparticles (10–30 nm) uniformly dispersed in a water-based fluid using the Advanced Photon Source at Argonne National
Laboratory. Size distributions for the suspended nanoparticles were derived by fitting experimental data to an established
model. Thermal conductivity of the SiO2 nanofluids was also measured, and the relation between the average particle size and the thermal conductivity enhancement
was established. The experimental data contradict models based on fluid interfacial layers or Brownian motion but support
the concept of thermal resistance at the liquid–particle interface. 相似文献
17.
《Current Applied Physics》2010,10(6):1442-1447
This paper presents a novel, inexpensive and one-step approach for synthesis of silver nanoparticles (Ag NPs) using arc discharge between titanium electrodes in AgNO3 solution. The resulting nanoparticles were characterized using UV–Vis spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Silver nanoparticles of 18 nm diameter were formed during reduction of AgNO3 in plasma discharge zone. Optical absorption spectroscopy of as prepared samples at 15 A arc current in AgNO3 solution shows a surface plasmon resonance around 410 nm. It was found that sodium citrate acts as a stabilizer and surface capping agent of the colloidal nanoparticles. SEM images exhibit the increase of reduced nanoparticles in 6 min arc duration compared with 1 min arc duration. TEM image of the sample prepared at 6 min arc duration shows narrow size distribution with 18 nm mean particle size. Antibacterial activities of silver nanoparticles were investigated at the presence of Escherichia coli (E-coli) bacteria. 相似文献
18.
M. Miettinen M. Johansson S. Suvanto J. Riikonen U. Tapper T. T. Pakkanen V.-P. Lehto J. Jokiniemi A. Lähde 《Journal of nanoparticle research》2011,13(10):4631-4645
Silicon–carbon nanoceramics have been synthesised from hexamethyldisilane (HMDS) by the atmospheric pressure chemical vapour
synthesis (APCVS). Direct aerosol phase synthesis enables continuous production of high purity materials in one-stage process.
The particle formation is based on the decomposition of the precursor in a high temperature reactor. Reaction of the gas phase
species leads to homogeneous nucleation and formation of the nanoparticles with a narrow size distribution (geometric mean
diameter range of particle number size distribution 160–200 nm with 1.5–1.6 geometric standard deviation at reaction temperatures
800–1200 °C). A systematic investigation of the influence of the process temperature on the powder characteristics, including
the particle size, crystallinity, chemical structure, surface and bulk composition and surface morphology, was carried out.
At the reactor temperature of 800 °C, the synthesised nanoparticles were amorphous preceramics containing mostly SiC4, Si–CH2–Si and Si–H units. The composition of the powder turned towards nanocrystalline 3C–SiC (crystal size under 2 nm) when the
reaction temperature was increased to 1200 °C. The reaction temperature appeared to be a key parameter controlling the structure
and properties of the synthesised powders. 相似文献
19.
This article reports a novel method to prepare MgAl2O4 spinel nanoparticles. By calcining a powder mixture of bayerite and magnesium sulfate at 800 °C and washing with water, single-phase
MgAl2O4 spinel nanoparticles were prepared. The powder mixture and the calcined products were characterized by differential thermal
and thermogravimetric analysis (DSC-TG), X-ray diffraction (XRD), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller
(BET) nitrogen-gas adsorption method. The obtained MgAl2O4 spinel nanoparticles have an average particle size of 12 nm, a narrow size distribution, and weak agglomeration. The specific
surface area of the MgAl2O4 spinel powder is 110 m2/g. The formation of MgAl2O4 spinel is attributed to a solid-state reaction between γ-Al2O3 and MgSO4. 相似文献
20.
A. Sennuga J. van Marwijk A. Boshoff C. G. Whiteley 《Journal of nanoparticle research》2012,14(5):824
The chaperonin protein GroEL was mixed with varying concentrations of K2PtCl4 followed by a 20-fold concentration of sodium borohydride to afford GroEL–platinum nanoparticle complexes in a ratio of between
1:25 and 1:2,000. Typical colour change, from colourless or pale yellow to brown, occurred that was dependent on the amount
of platinum present. These complexes were characterised by UV/Vis, inductively coupled plasma optical emission spectroscopy,
Fourier transform infra red, transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy. TEM analysis
revealed that the size of nanoparticles increased as the molar ratio of platinum to GroEL increased with an average size diameter
of 1.72–3.5 nm generated with GroEL–platinum molar ratios of 1:125–1:2,000. Fourier-transform infrared spectroscopy (FTIR)
spectra showed no distinct changes in the structure of GroEL but confirmed that the nanoparticles were attached to the protein.
The effect of platinum nanoparticles on the ATPase activity of GroEL showed an activity of 5.60 μmol min−1 ml−1 (87 % increase over a control) at the molar ratio of GroEL–platinum nanoparticles of 1:25. 相似文献