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1.
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
2.
Miguel A. Aguilar-Méndez Eduardo San Martín-Martínez Lesli Ortega-Arroyo Georgina Cobián-Portillo Esther Sánchez-Espíndola 《Journal of nanoparticle research》2011,13(6):2525-2532
Colloidal silver nanoparticles were synthesized by reducing silver nitrate solutions with glucose, in the presence of gelatin
as capping agent. The obtained nanoparticles were characterized by means of UV–Vis spectroscopy, transmission electron microscopy
(TEM), and Fourier transform infrared (FTIR) spectroscopy. The response surface methodology (RSM) was also used to determine
the influence of the variables on the size of the nanoparticles. The antifungal activity of the silver nanoparticles was evaluated
on the phytopathogen Colletotrichum gloesporioides, which causes anthracnose in a wide range of fruits. The UV–Vis spectra indicated the formation of silver nanoparticles preferably
spherical and of relatively small size (<20 nm). The above-mentioned was confirmed by TEM, observing a size distribution of
5–24 nm. According to RSM the synthesis variables influenced on the size of the silver nanoparticles. By means of FTIR spectroscopy
it was determined that gelatin, through their amide and hydroxyl groups, interacts with nanoparticles preventing their agglomeration.
The growth of C. gloesporioides in the presence of silver nanoparticles was significantly delayed in a dose dependent manner. 相似文献
3.
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
4.
A green method, using pulsed spark-discharge (PSD) to synthesize gold nanoparticles (AuNPs) in ethanol, is studied in this
article. Unlike conventional methods for metal nanoparticles synthesis, the PSD method does not require the addition of chemical
surfactants and stabilizers. The size of PSD–AuNPs is examined by transmission electron microscopy, with a range 5–50 nm.
The chemical compounds, crystal structure, and surface plasmon resonance of PSD–AuNPs are studied using energy dispersive
X-ray spectroscopy, X-ray diffraction, and UV–Visible spectroscopy, respectively. Zeta potential analysis shows that a negative
charge (−40 mV) on the surface of the PSD–AuNPs may be contributing to the stability of the suspension. During the gold electrodes
discharge in the ethanol, under an intensive electric field and thermal energy, bulk metallic gold and ethanol may produce
AuNPs and varieties of chemical derivatives, which are also studied by GC/MS and FTIR to investigate the suspension mechanism.
The analysis results show that there is an oxidation reaction of ethanol occurring during the PSD process to produce ethanol
derivatives, such as acetaldehyde, acetic acid, and ethyl acetate, which may modify the surface of AuNPs by coordination of
oxygen atoms. However, only acetic acid can form a negative charge by the deprotonation of the carboxylic group of surface
in ethanol, resulting in the creation of a repulsion force between the particles to form the stable colloid system. The experimental
results indicate that PSD is an alternative green process to synthesize gold nanoparticles suspension in ethanol. Moreover,
with a gold rod consumption rate of 15 mg/L, concentrations of gold nanoparticles ~9 ppm have been observed; therefore, the
net production rate is around 60%. 相似文献
5.
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
6.
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
7.
G. A. Martínez-Castañón N. Niño-Martínez F. Martínez-Gutierrez J. R. Martínez-Mendoza Facundo Ruiz 《Journal of nanoparticle research》2008,10(8):1343-1348
Silver nanoparticles with different sizes (7, 29, and 89 nm mean values) were synthesized using gallic acid in an aqueous
chemical reduction method. The nanoparticles were characterized using transmission electron microscopy (TEM), dynamic light
scattering (DLS), X-ray diffraction (XRD), and ultraviolet–visible (UV–Vis) absorption spectroscopy; the antibacterial activity
was assessed using the standard microdilution method, determining the minimum inhibitory concentration (MIC) according to
the National Committee for Clinical Laboratory Standards. From the microscopies studies (TEM) we observed that silver nanoparticles
have spherical (7 and 29 nm) and pseudospherical shape (89 nm) with a narrow size distribution. The sizes of the silver nanoparticles
were controlled by varying some experimental conditions. It was found that the antibacterial activity of the nanoparticles
varies when their size diminishes. 相似文献
8.
Gold nanoparticles have been studied for many biomedical applications. However, alterations in the gold nanoparticles’ environment
frequently lead to the formation of aggregates and agglomerates, which have not been well characterized. These new structures
could significantly change the biological impact of the nanoparticles, so the appropriate characterization of these structures
prior to biological administration is vital for the correct interpretation of toxicology results. By varying the solvent or
heating under pressure, four reproducible gold nanoparticles structures were created: 10 nm primary particles, aggregates
of the primary particles that contain non-reversible bonds between the individual nanoparticles, agglomerates of primary particles
that contain reversible interactions between the individual nanoparticles, and agglomerated aggregates that have reversible
bonds linking individual aggregates. Ultraviolet–visible (UV–Vis) spectroscopy, thermal gravitational analysis, and neutron
activation analysis were each found to accurately measure the concentration of the primary particles. The primary particles
measured 10 nm by dynamic light scattering (DLS) and had a spherical morphology by transmission electron microscopy (TEM)
while the aggregates measured 110 nm by DLS and had a distorted morphology by TEM. The agglomerate and aggregated agglomerate
samples both measured >1,000 nm by DLS, but the individual particles had significantly different morphologies by TEM. Multiple
other analytical techniques, including ultracentrifugation, gel electrophoresis, and X-ray diffraction, also showed unique
traits for each structure. The structural differences did not change in the presence of cell culture media or rat serum. In
addition, the primary particles, aggregates, and agglomerates each had a unique UV–Vis spectrum, allowing for an inexpensive,
rapid method to differentiate between the structures. 相似文献
9.
Benjamin Marchetti Yvonne Joseph Helmut Bertagnolli 《Journal of nanoparticle research》2011,13(8):3353-3362
Alkylamine-capped gold nanoparticles were synthesised using the Leff method. In order to investigate the influence on the
complexes formed during the synthesis and the final size of the protected nanoparticles the chain length of the stabilizing
ligands varied. Phase transfer and amine complex formation were studied in solution with X-ray absorption spectroscopy. The
phase transfer complexes retain the quadratic planar conformation whilst all alkyl amines form a linear coordinated gold(I)
complex. After reduction, the particles were characterised in solution with EXFAS, UV–Vis spectroscopy, and compared to TEM
measurements. The size of the particles was determined from the coordination number of the first gold shell. The position
of the UV–Vis plasmon band and the distance of the first gold shell were used to qualitatively compare the effects of the
ligands on the particle size. The size of the particles decreases with increasing chain length. 相似文献
10.
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
11.
E. Ventosa A. Colina A. Heras V. Ruiz J. Garoz J. López-Palacios 《Journal of nanoparticle research》2012,14(1):661
In this paper, we report the preparation of highly stable gold nanoparticles/poly(3,4-ethylendioxythiophene) nanocomposites
by a one-pot chemical route in aqueous medium without surfactants to increase the solubility of the monomer (3,4-ethylendioxythiophene,
EDOT) or to stabilize gold nanoparticles (Au NPs). The generation of the nanocomposite was followed by UV–Visible transmission
spectroscopy combined with multivariate curve resolution alternating least squares analysis to deconvolute the individual
spectra of the different species generated in the synthesis: oligomers, polymer and gold nanoparticles. The plasmon band observed
at 530 nm during the synthesis step indicates the generation of gold nanoparticles. The influence of monomer and metal precursor
concentration and their concentration ratios on Au NP size were analyzed. The electrochromic properties of the composite were
investigated by UV–Visible absorption spectroelectrochemistry, being mainly related to polymer oxidation and reduction. The
main difference observed is the hypsochromic shift of the polymer spectra due to the gold nanoparticles inside the polymer.
Multicyclic spectroelectrochemical experiments evidence a high stability and adhesion of the nanocomposite. 相似文献
12.
Deshpande Raghunandan Bedre D. Mahesh S. Basavaraja S. D. Balaji S. Y. Manjunath A. Venkataraman 《Journal of nanoparticle research》2011,13(5):2021-2028
Our research interest centers on microwave-assisted rapid extracellular synthesis of bio-functionalized silver nanoparticles
of 26 ± 5 nm from guava (Psidium guajava) leaf extract with control over dimension and composition. The reaction occurs very rapidly as the formation of spherical
nanoparticles almost completed within 90 s. The probable pathway of the biosynthesis is suggested. Appearance, crystalline
nature, size and shape of nanoparticles are understood by UV–vis (UV–vis spectroscopy), FTIR (fourier transform infrared spectroscopy),
XRD (X-ray diffraction), FESEM (field emission scanning electron microscopy) and TEM (transmission electron microscopy) techniques.
Microwave-assisted route is selected for the synthesis of silver nanoparticles to carry out the reaction fast, suppress the
enzymatic action and to keep the process environmentally clean and green. 相似文献
13.
M. T. Laranjo T. B. L. Kist E. V. Benvenutti M. R. Gallas T. M. H. Costa 《Journal of nanoparticle research》2011,13(10):4987-4995
The dispersion of gold nanoparticles (AuNPs) in solid matrices, maintaining their optical properties as in liquid medium,
has been explored, enlarging the possibilities of handling and applications of these nanoparticles. In this study, AuNPs were
successfully enclosed in silica using the sol–gel method and high-pressure processing at 7.7 GPa, at room temperature, obtaining
compacts with densities as high as 85% of silica glass and Vickers microhardness of 50% of quartz. This densification was
confirmed by the reduced values of specific surface area and closed pores. UV–Vis spectra showed that the AuNPs maintain their
optical properties, in the monoliths and in the compacts, presenting an absorption band in the characteristic region of AuNPs
smaller than 20 nm. The slight red-shifts of the absorption peaks cannot be explained in the same way as for AuNPs in solution,
where it is associated to an increase in particle diameter. In solid samples, additional factors as matrix properties should
be considered. Transmission electron microscopy (TEM) images showed that the AuNPs have spherical shape both in solution and
in the monolith, with an average diameter not exceeding 10 nm. It was also observed that the high-pressure processing did
not destroy or misshape the AuNPs. 相似文献
14.
Uğur Tamer İsmail H. Boyacı Erhan Temur Adem Zengin İlker Dincer Yalçın Elerman 《Journal of nanoparticle research》2011,13(8):3167-3176
The preparation and application of rod-shaped core–shell structured Fe3O4–Au nanoparticles for immunomagnetic separation and sensing were described for the first time with this study. To synthesize
magnetic gold nanorod particles, the seed-mediated synthetic method was carried out and the resulting nanoparticles were characterized
with transmission electron microscopy (TEM), ultraviolet visible spectroscopy (UV–Vis), energy-dispersive X-ray (EDX), and
X-ray diffraction (XRD). Magnetic properties of the nanoparticles were also examined. Characterization of the magnetic gold
nanorod particles has proven that the resulting nanoparticles were composed of Fe3O4 core and the gold shell. The rod-shaped gold-coated iron nanoparticles have an average diameter of 16 ± 2 nm and an average
length of about 50 ± 5 nm (corresponding aspect ratio of 3). The saturation magnetization value for the magnetic gold nanorod
particles was found to be 37 emu/g at 300 K. Rapid and room temperature reaction synthesis of magnetic gold nanorod particles
and subsequent surface modification with E. coli antibodies provide immunomagnetic separation and SERS application. The analytical performance of the SERS-based homogenous
sandwich immunoassay system with respect to linear range, detection limit, and response time is also presented. 相似文献
15.
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
16.
We report the experimental results on temperature-dependent studies of interactions between a novel biocompatible thermosensitive
polymer hydrogel and different stabilizing agent capped gold nanoparticles (Au NPs) with particle size ranging from 5 to 20 nm.
Stabilizing agents such as thioglycolic acid, tryptophan, and phenylalanine have been used as capping agents for Au NPs. The
poly-N-isopropyl acrylamide-co-acrylic acid (pNIPAm-AAc) with 3.0 ± 0.7 μm in size was synthesized by radical polymerization of
a selected mixture of N-isopropyl acrylamide (NIPAm), methylene-bis-acrylamide and acrylic acid (AAc). The capped Au NPs were mixed with a solution
of pNIPAm-AAc hydrogel. The temperature-dependent properties of the mixture were studied by UV–vis spectroscopy, dynamic light
scattering based particle size analysis, and transmission electron microscopy (TEM). The observations indicated change in
the lower critical solution temperature (LCST) depending on the nature of the stabilizer, with hydrophobic ones lowering the
value while hydrophilic stabilizers increasing the same. Also, the optical absorption due to Au NPs, when stabilized with
hydrophobic groups, reduced significantly at above LCST along with significant blue shift of wavelength maximum. 相似文献
17.
Gold nanoparticles have been precipitated on the surface of quartz slides covered with titanium (IV) butoxide. UV irradiation
of modified quartz slides immersed into water solutions of hydrogen tetrachloroaurate of different concentrations (2.5 × 10−4–1.0 × 10−2 M) has been used for this purpose. Properties of produced samples have been investigated by UV–Vis spectroscopy, IR spectroscopy,
SEM-EDX, TGA, and AFM. According to the obtained data, produced gold particles are distributed on modified quartz surface
very uniformly and the average size of gold particles is about 30–50 nm. 相似文献
18.
One-pot synthesis of well dispersed, size-controlled gold nanoparticles with the average size of 10–15 nm and luminescent
gold nanoclusters with average size of 1.7–2.0 nm were successfully achieved by thermal decomposition of gold organometallic
precursor CH3AuPPh3 in the presence of thiol surfactants in o-xylene. Only difference between the preparations of two types of Au nanoparticles is the amount of thiol surfactant employed.
The mechanistic study of formation of gold nanoparticles was carried out by analyzing the samples at different reaction time
intervals and revealed that two-staged growth process was involved. The nanoclusters showed strong red emission with the maximum
intensity at about 600 nm. The maximum room temperature photoluminescence quantum yield was measured as 1.2%. The catalytic
ability of the Au nanoclusters to promote Suzuki–Miyaura coupling involving the C–C bond formation was also investigated. 相似文献
19.
Synthesis,characterization and role of zero-valent iron nanoparticle in removal of hexavalent chromium from chromium-spiked soil 总被引:3,自引:0,他引:3
Chromium is an important industrial metal used in various products/processes. Remediation of Cr contaminated sites present
both technological and economic challenges, as conventional methods are often too expensive and difficult to operate. In the
present investigation, Zero-valent iron (Fe0) nanoparticles were synthesized, characterized, and were tested for removal of Cr(VI) from the soil spiked with Cr(VI). Fe0 nanoparticles were synthesized by the reduction of ferric chloride with sodium borohydride and were characterized by UV–Vis
(Ultra violet–Visible) and FTIR (Fourier transform infrared) spectroscopy. The UV–Vis spectrum of Fe0 nanoparticles suspended in 0.8% Carboxymethyl cellulose showed its absorption maxima at 235 nm. The presence of one band
at 3,421 cm−1 ascribed to OH stretching vibration and the second at 1,641 cm−1 to OH bending vibration of surface-adsorbed water indicates the formation of ferrioxyhydroxide (FeOOH) layer on Fe0 nanoparticles. The mean crystalline dimension of Fe0 nanoparticles calculated by XRD (X-ray diffraction) using Scherer equation was 15.9 nm. Average size of Fe0 nanoparticles calculated from TEM (Transmission electron microscopy) images was found around 26 nm. Dynamic Light Scattering
(DLS) also showed approximately the same size. Batch experiments were performed using various concentration of Fe0 nanoparticles for reduction of soil spiked with 100 mg kg−1 Cr(VI). The reduction potential of Fe0 nanoparticles at a concentration of 0.27 g L−1 was found to be 100% in 3 h. Reaction kinetics revealed a pseudo-first order kinetics. Factors like pH, contact time, stabilizer,
and humic acid facilitates the reduction of Cr(VI). 相似文献
20.
Garima Singhal Riju Bhavesh Kunal Kasariya Ashish Ranjan Sharma Rajendra Pal Singh 《Journal of nanoparticle research》2011,13(7):2981-2988
Development of green nanotechnology is generating interest of researchers toward ecofriendly biosynthesis of nanoparticles.
In this study, biosynthesis of stable silver nanoparticles was done using Tulsi (Ocimum sanctum) leaf extract. These biosynthesized nanoparticles were characterized with the help of UV–vis spectrophotometer, Atomic Absorption
Spectroscopy (AAS), Dynamic light scattering (DLS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR),
and Transmission electron microscopy (TEM). Stability of bioreduced silver nanoparticles was analyzed using UV–vis absorption
spectra, and their antimicrobial activity was screened against both gram-negative and gram-positive microorganisms. It was
observed that O. sanctum leaf extract can reduce silver ions into silver nanoparticles within 8 min of reaction time. Thus, this method can be used
for rapid and ecofriendly biosynthesis of stable silver nanoparticles of size range 4–30 nm possessing antimicrobial activity
suggesting their possible application in medical industry. 相似文献