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1.
Salunkhe RB Patil SV Salunke BK Patil CD Sonawane AM 《Applied biochemistry and biotechnology》2011,165(1):221-234
Development of reliable and eco-friendly processes for synthesis of metallic nanoparticles is an important step in the field
of application of nanotechnology. Biological systems provide a useful option to achieve this objective. In this study, potent
fungal strain was selectively isolated from soil samples on silver supplemented medium, followed by silver tolerance (100–1,000 ppm)
test. The isolated fungus was subjected to morphological, 18S rRNA gene sequencing and phylogenic studies and confirmed as
Cochliobolus lunatus. The silver accumulation and nanoparticle formation potential of wet cell mass of C. lunatus was investigated. The accumulation and nanoparticle formation by wet fungal cell mass with respect to pH change was also
studied. The desorbing assay was used to recover accumulated silver from cell mass. C. lunatus was found to produce optimum biomass (0.94 g%) at 635 ppm of silver. Atomic absorption spectroscopy study showed that at
optimum pH (6.5 ± 0.2), cell mass accumulates 55.6% of 100 ppm silver. SEM and FTIR studies revealed that the cell wall of
C. lunatus is the site of silver sorption, and certain organic groups such as carbonyl, carboxyl, and secondary amines in the fungal
cell wall have an important role in biosorption of silver in nanoform. XRD determined the FCC crystalline nature of silver
nanoparticles. TEM analysis established the shape of the silver nanoparticles to be spherical with the presence of very small-sized
nanoparticles. Average size of silver nanoparticles (14 nm) was confirmed by particle sizing system. This study reports the
synthesis and accumulation of silver nanoparticles through reduction of Ag+ ions by the wet cell mass of fungus C. lunatus. 相似文献
2.
Murugan Veerapandian Suk Kyung Lim Hyang Mi Nam Gobianand Kuppannan Kyusik S. Yun 《Analytical and bioanalytical chemistry》2010,398(2):867-876
We report the analytical and in vitro antibacterial activity of glucosamine-functionalized silver glyconanoparticles. Morphological
characterization ensured the surface topography and particle size distribution of both silver and glucosamine–silver nanoparticles.
Surface plasmon resonance of both types of nanoparticle was determined from UV–visible spectroscopy using four different sample
concentrations (10–40 μL). The resulting functionalized glyconanoparticles show maximum absorbance with a red shift of 30 ± 5 nm
(390–400 nm) from their initial absorbance (425–430 nm). FT-Raman and 1H-NMR spectroscopic measurement confirmed the surface functionalization of glucosamine on the silver surface through the carbonyl
group of a secondary amide linkage (–NH–CO–), elucidated by the conjugation of N-hydroxysuccinimide (NHS)-terminated silver nanoparticles and the amino group of glucosamine. Antimicrobial experiments with
well-characterized silver nanoparticles (AgNPs) and glucosamine-functionalized silver nanoparticles (GlcN-AgNPs) demonstrate
that GlcN-AgNPs have similar and enhanced minimum inhibitory concentration (MIC) against eight gram-negative and eight gram-positive
bacteria compared with AgNPs. MIC data shows that Klebsiella pneumoniae (ATCC 700603) and Bacillus cereus isolate express high levels of inhibition, with the quantity and magnitude of inhibition being higher in the presence of
GlcN-AgNPs. 相似文献
3.
Magdalena Stevanović Igor Savanović Vuk Uskoković Srečo D. Škapin Ines Bračko Uroš Jovanović Dragan Uskoković 《Colloid and polymer science》2012,290(3):221-231
A simple and green chemical method has been developed to synthesize stable bare and capped silver nanoparticles based on the
reduction of silver ions by glucose and capping by poly(α,γ,l-glutamic acid) (PGA). The use of ammonia during synthesis was avoided. PGA has had a dual role in the synthesis and was used
as a capping agent to make the silver nanoparticle more biocompatible and to protect the nanoparticles from agglomerating
in the liquid medium. The synthesized PGA-capped silver nanoparticles in the size range 5–45 nm were stable over long periods
of time, without signs of precipitation. Morphological examination has shown that the silver nanoparticles had a nearly spherical,
multiply twinned structure. The effects of the reaction temperature and the reaction time during the synthesis were investigated
too. The biocompatibility of the PGA-capped silver nanoparticles is discussed in terms of in vitro toxicity with human intestinal
Caco-2 cells. The samples were characterized by UV–Visible spectroscopy, field emission scanning electron microscopy, transmission
electron microscopy, and zeta potential measurements. 相似文献
4.
Jyotirmayee Mohanty Dipak K Palit Laxminarayan V Shastri Avinash V Sapre 《Journal of Chemical Sciences》2000,112(1):63-72
Laser flash photolysis studies were carried out on two types of silver nanoparticles prepared byγ-radiolysis of Ag+ solutions in the presence of polyphosphate as the stabiliser. Type I silver nanoparticles displayed a surface plasmon band
at 390 nm. Type II silver nanoparticles showed a 390 nm surface plasmon band with a shoulder at 550 nm. On photoexcitation
in the surface plasmon band region, using 35 picosecond laser pulses at 355 nm and 532 nm, the type II solutions showed transient
bleaching and absorption signals in the 450–900 nm region, which did not decay appreciably up to 5 nanoseconds. These transient
changes were found to get annealed in the intervalt where 5 ns<t< 100 ns. Extended photolysis of the nanoparticle solutions with repetitive laser pulses resulted in a decrease in the values
of the average particle size which were measured by employing the dynamic light scattering technique. 相似文献
5.
Silver nanoparticles preparation and the aggregation stability of the particles was investigated in lamellar liquid crystalline
systems. A liquid crystal of HDTABr/pentanol/water was first prepared. The water content was next increased while keeping
the mass ratio of HDTABr and pentanol constant. Silver nanoparticles were produced by replacing the aqueous phase by Ag sols
of various concentrations (0.5–5×10–3 mol/l) or by an in situ preparation method, i.e., interlamellar reduction of Ag+ ions in the liquid crystalline phase. The stability of the silver nanoparticles was monitored by UV-VIS spectroscopy and
TEM. The particle size ranged from 5 to 44 nm. The kinetic of silver nanoparticle aggregation was investigated. The effect
of nanoparticles on structural ordering in liquid crystals was studied by XRD measurements and it was established that the
lamellar distance (dL) was only slightly altered.
Electronic Publication 相似文献
6.
Jong Hwa Sohn Long Quoc Pham Hyun Suk Kang Ji Hyun Park Byung Cheol Lee Young Soo Kang 《Radiation Physics and Chemistry》2010,79(11):1149-1153
Conducting silver paste was prepared by using Ag nanoparticles which were synthesized by e-beam irradiation method (from KAERI); its conductivity was comparatively determined with Ag nanoparticles which were prepared by thermolysis method (commercial). The silver nanoparticles with the diameter of approximately 150 nm size prepared by e-beam irradiation were mixed with glass frit and sintered for 1 h at 500 °C. It is presumably concluded that the wt% of silver nanoparticle, size distribution and homogenous dispersibility of Ag nanoparticles in the pastes are the critical factors for the high conductivity of the paste. Among the various wt% of silver nanoparticle in the conducting silver pastes, silver paste with 90 wt% of silver nanoparticle has the highest conductivity as 1.6×104 S cm?1. This conductivity value is 1.6 times higher than the Ag pastes which were prepared with silver nanoparticles obtained by thermolysis method. 相似文献
7.
A. I. Bulavchenko P. S. Popovetskiy 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(6):999-1003
The possibility of determining the sizes of micelles of sodium di(2-ethylhexyl)sulfosuccinate (AOT) with silver nanoparticles
in decane against the background of a large excess of empty micelles by means of photon correlation spectroscopy with unimodal
analysis of the autocorrelation function is demonstrated. Contributions from all components to the light scattering are estimated
by measuring the static (Rayleigh) light scattering and allowing for partial absorption of the laser radiation by silver nanoparticles.
Areas of the correct determination of the hydrodynamic radius of the micelles with nanoparticles are determined via unimodal
analysis of the autocorrelation function in dependence on the nanoparticle size (10–2 nm) and silver concentration (1–30 mM)
at a constant AOT concentration (0.25 mol/L) and aqueous pseudophase content (1 vol %). 相似文献
8.
Mircea Stefanescu Marcela Stoia Oana Stefanescu Paul Barvinschi 《Journal of Thermal Analysis and Calorimetry》2010,99(2):459-464
This article presents a study on obtaining Ni, Zn ferrite starting from Fe(III), Ni (II), Zn (II) nitrates and some polyols:
1,2-propane diol, 1,3-propane diol and glycerol. While heating, a redox reaction takes place between nitrate anion and polyol,
with formation of carboxylate type precursors. The obtained precursors have been investigated by thermal analysis, FT-IR spectrometry
and atomic absorption spectroscopy. The thermal decomposition of the synthesized precursors up to 350 °C leads to the formation
of Ni, Zn ferrite as unique phase, evidenced by XRD. The average diameter of the ferrite crystallites, estimated from XRD
data, takes values within the range 20–50 nm, depending on the annealing temperature. Transmission Electron Microscopy has
evidenced the obtaining of spherical, agglomerated nanoparticles. The magnetic properties of the synthesized samples, measured
in cvasistatic magnetic field (50 Hz) are characteristic for the Ni, Zn ferrite nanoparticles, with narrow hysteresis cycle
and values of the saturation magnetization <70 emu/g. 相似文献
9.
《Radiation Physics and Chemistry》2009,78(4):251-255
Highly stable silver nanoparticles were successfully synthesized by gamma ray irradiation in the presence of sodium alginate. The silver nanoparticles were characterized by UV–vis spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). Their particle sizes were in the range of 6–30 nm. The as-obtained Ag nanoparticle dispersion was stable for over 6 months at room temperature. 相似文献
10.
Nanocomposite ZnO–Ag thin film containing nano-sized Ag particles have been grown on glass substrate by spin-coating technique
using zinc acetate dihydrate as starting precursor in 2-propanol as solvent and monoethanolamine as stabilizer. Silver nanoparticles
were added in the ZnO sol using silver nitrate dissolved in ethanol-acetonitrile. Their structural, electrical, crystalline
size and optical properties were investigated as a function of preheating, annealing temperature and silver content. The results
indicated that the crystalline phase was increased with increase of annealing temperature up to 550 °C at optimum preheating
temperature of 275 °C. Thermal gravimetric differential thermal analysis results indicated that the decomposition of pure
ZnO and nanocomposite ZnO–Ag precursors occurred at 225 and 234 °C, respectively with formation of ZnO wurtzite crystals.
The scanning electron microscopy and atomic force microscopy revealed that the surface structure (the porosity and grain size)
of the ZnO–Ag thin film (the film thickness is about 379 nm) was changed compared to pure ZnO thin film. The result of transmission
electron microscopy showed that Ag particles were about 5 nm and ZnO particles 58 nm with uniform silver nanoclusters. Optical
absorption results indicated that optical absorption of ZnO–Ag thin films decreased with increase of annealing temperature.
Nanocomposite ZnO–Ag thin films with [Ag] = 0.068 M and [Ag] = 0.110 M showed an intense absorption band, whose maximum signals
appear at 430 nm which is not present in pure ZnO thin films. The result of X-ray photoelectron spectroscopy revealed that
the binding energy of Ag 3d5/2 for ZnO–Ag shifts remarkably to the lower binding energy compared to the pure metallic Ag due to the interaction between
Ag and ZnO. 相似文献
11.
《Journal of separation science》2018,41(4):982-989
A new silver‐functionalized silica‐based material with a core–shell structure based on silver nanoparticle‐coated silica spheres was synthesized, and silver nanoparticles were modified using strongly bound l‐ cysteine. l‐ Cysteine‐silver@silica was characterized by scanning electron microscopy and FTIR spectroscopy. Then, a solid‐phase extraction method based on l‐ cysteine‐silver@silica was developed and successfully used for bisphenol A determination prior to HPLC analysis. The results showed that the l‐ cysteine‐silver@silica as an adsorbent exhibited good enrichment capability for bisphenol A, and the maximum adsorption saturation was 20.93 mg/g. Moreover, a short adsorption equilibrium time was obtained due to the presence of silver nanoparticles on the surface of the silica. The extraction efficiencies were then optimized by varying the eluents and pH. Under the optimized conditions, good linearity for bisphenol A was obtained in the range from 0.4 to 4.0 μM (R2 > 0.99) with a low limit of detection (1.15 ng/mL). The spiked recoveries from tap water and milk samples were satisfactory (85–102%) with relative standard deviations below 5.2% (n = 3), which indicated that the method was suitable for the analysis of bisphenol A in complex samples. 相似文献
12.
Daniela de Araújo Viana Carolina de Albuquerque Lima Rejane Pereira Neves Cristina Souza Mota Keila Aparecida Moreira José Luiz de Lima-Filho Maria Taciana Holanda Cavalcanti Attilio Converti Ana Lúcia Figueiredo Porto 《Applied biochemistry and biotechnology》2010,162(3):830-842
Cow raw milk from dairy cooperatives was examined for its microbial composition. Among the isolates identified, 17.6% were
yeasts. The most frequent genus was Candida, although members belonging to the genera Brettanomyces, Dekkera, and Geotricum were also identified. Although qualitative and quantitative tests for extracellular proteolytic activity were positive for
all the species isolated, Candida buinensis showed the highest response (23.5 U/mg); therefore, it was selected for subsequent investigation. The results of fermentations
carried out at variable temperature, pH, and soybean flour concentration, according to a 23 full factorial design, demonstrated that this yeast ensured the highest production of extracellular proteases (573 U/mL)
when cultivated at 35 °C, pH 6.5, and using soybean flour concentrations in the range 0.1–0.5% (w/v). The cell-free supernatants showed the highest activity at 25 °C and pH 7.0, and satisfactory stability in the ranges 25–30 °C
and pH 7–9. The first-order rate constants of protease inactivation in the cell-free supernatants were calculated at different
temperatures from semi-log plots of the residual activity versus time and then used in Arrhenius and Eyring plots to estimate
the main thermodynamic parameters of thermoinactivation (E* = 40.0 kJ/mol; ΔH* = 37.3 kJ/mol; ΔS* = −197.5 J/mol K; ΔG* = 101 kJ/mol). 相似文献
13.
Mesoporous carbons containing silver nanoparticles have been successfully synthesized under acidic conditions by employing
resorcinol and formaldehyde as carbon precursors and triblock copolymer EO101PO56EO101 (Lutrol F127) as a soft template. Silver nanoparticles of ∼90 nm were added to the synthesis mixture to achieve 10 wt% and
20 wt% of Ag loading in the carbon. Also, tetraethyl orthosilicate (TEOS) was introduced to the system in order to improve
adsorption properties of the silver-carbon composites and to reinforce its structure. The resulting carbons with incorporated
silver nanoparticles featured high surface areas, large total pore volumes and primary mesopores in the range between ∼6–7 nm. 相似文献
14.
Bolea E Jiménez-Lamana J Laborda F Castillo JR 《Analytical and bioanalytical chemistry》2011,401(9):2723-2732
A method for determining the size of silver nanoparticles and their quantification by asymmetric flow field-flow fractionation
coupled with inductively coupled plasma mass spectrometry (ICP-MS) is proposed and was tested in consumer products. Experimental
conditions were studied in detail to avoid aggregation processes or alteration of the original size distributions. Additionally,
losses from sorption processes onto the channel membrane were minimized for correct quantification of the nanoparticles. Mobile
phase composition, injection/focusing, and fractionation conditions were evaluated in terms of their influence on both separation
resolution and recovery. The ionic strength, pH, and the presence of ionic and nonionic surfactants had a strong influence
on both separation and recovery of the nanoparticles. In general, better results were obtained under those conditions that
favored charge repulsions with the membrane. Recovery values of 83 ± 8% and 93 ± 4% with respect to the content of silver
nanoparticles were achieved for the consumer products studied. Silver nanoparticle standards were used for size calibration
of the channel. The results were compared with those obtained by photon correlation spectroscopy and images taken by transmission
electron microscopy. The quantification of silver nanoparticles was performed by direct injection of ionic silver standard
solutions into the ICP-MS system, integration of the corresponding peaks, and interpolation of the fractogram area. A limit
of detection of 5.6 μg L-1 silver, which corresponds to a number concentration of 1×1012 L-1 for nanoparticles of 10 nm, was achieved for an injection volume of 20 μL. 相似文献
15.
Jongho Kim Sang Wook Kang Yong Soo Kang 《Colloids and surfaces. A, Physicochemical and engineering aspects》2008,320(1-3):189-192
Partially positively charged silver nanoparticles were successfully prepared by interaction between p-benzoquinone and the surface of the nanoparticles. This result was primarily due to electron affinity of the carbonyl group in p-benzoquinone, as confirmed by FT-IR and X-ray photoelectron spectroscopy (XPS). In this study, p-benzoquinone acted as both a stabilizer and a reducing agent for silver nanoparticles. UV–vis spectra showed the formation of silver nanoparticles. TEM micrographs confirmed that most of silver nanoparticles exist in sizes less than 7 nm, and the average size of particle aggregates is approximately 20 nm. 相似文献
16.
Rodrigo Del Río Francisco Armijo Ricardo Schrebler Cesar Gutierrez Andrea Amaro Sonia R. Biaggio 《Journal of Solid State Electrochemistry》2011,15(4):697-702
In this work, the poly(styrene-vynil pyridine) block copolymer was used as a porous pattern to study the electrodeposition
of gold inside the pores, as a new method to obtain gold nanoparticles. The porous pattern left by the copolymer film onto
a conductive glass surface was characterized by atomic force microscopy (AFM), evidencing pores of 30 nm diameter. After the
electrodeposition, 30 nm diameter gold nanoparticles were obtained and they were characterized by cyclic voltammetry (CV)
and AFM, and then used to study the adsorption of glucose oxidase enzyme. The adsorption process of glucose oxidase on gold
nanowires was investigated by CV and electrochemical impedance spectroscopy. The morphological and capacitance results indicate
that the block copolymer–gold nanoparticle composite seems to be a good candidate to design biosensors and immunosensors. 相似文献
17.
Ting Li Brian Albee Matti Alemayehu Rocio Diaz Leigha Ingham Shawn Kamal Maritza Rodriguez Sandra Whaley Bishnoi 《Analytical and bioanalytical chemistry》2010,398(2):689-700
A comparative assessment of the 48-h acute toxicity of aqueous nanoparticles synthesized using the same methodology, including
Au, Ag, and Ag–Au bimetallic nanoparticles, was conducted to determine their ecological effect in freshwater environments
through the use of Daphnia magna, using their mortality as a toxicological endpoint. D. magna are one of the standard organisms used for ecotoxicity studies due to their sensitivity to chemical toxicants. Particle suspensions
used in toxicity testing were well-characterized through a combination of absorbance measurements, atomic force or electron
microscopy, flame atomic absorption spectrometry, and dynamic light scattering to determine composition, aggregation state,
and particle size. The toxicity of all nanoparticles tested was found to be dose and composition dependent. The concentration
of Au nanoparticles that killed 50% of the test organisms (LC50) ranged from 65–75 mg/L. In addition, three different sized Ag nanoparticles (diameters = 36, 52, and 66 nm) were studied
to analyze the toxicological effects of particle size on D. magna; however, it was found that toxicity was not a function of size and ranged from 3–4 μg/L for all three sets of Ag nanoparticles
tested. This was possibly due to the large degree of aggregation when these nanoparticles were suspended in standard synthetic
freshwater. Moreover, the LC50 values for Ag–Au bimetallic nanoparticles were found to be between that of Ag and Au but much closer to that of Ag. The bimetallic
particles containing 80% Ag and 20% Au were found to have a significantly lower toxicity to Daphnia (LC50 of 15 μg/L) compared to Ag nanoparticles, while the toxicity of the nanoparticles containing 20% Ag and 80% Au was greater
than expected at 12 μg/L. The comparison results confirm that Ag nanoparticles were much more toxic than Au nanoparticles,
and that the introduction of gold into silver nanoparticles may lower their environmental impact by lowering the amount of
Ag which is bioavailable. 相似文献
18.
G. V. Krylova Yu. I. Gnatyuk N. P. Smirnova A. M. Eremenko V. M. Gun’ko 《Journal of Sol-Gel Science and Technology》2009,50(2):216-228
A variety of Ag nanoparticles/oxide mesoporous films with templated silica, titania, and zirconia was synthesized by sol–gel
method at glass, aluminum, and silicon substrates using metal alkoxides (tetraethoxysilane, titanium tetraisopropoxide, and
zirconium tetrapropoxide) and AgNO3 as precursors of oxide films and Ag nanoparticles, respectively, and Pluronic P123 as a template agent. Oxide films alone
and Ag/oxide composites were characterized using hexane adsorption, X-ray diffraction (XRD), Raman and ultraviolet (UV)/vis
spectroscopies, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. The distribution of
Ag nanoparticles within the films, their sizes, intensity, and position of surface plasmon resonance (SPR) absorbance band
at λ = 400 nm, as well as the textural and structural characteristics of whole films depend on treatment temperature, types of
substrates and oxide matrices, oxide crystallization, and Ag content. Ag nanoparticles form preferably on the outer surface
of the films under lower sintering temperatures if the amount of loaded silver is low. Oxide crystallization (e.g., TiO2) promotes silver embedding into the outer film layer. At higher silver content (≥10 at.%) and higher calcination temperature
(873 K), silver nanoparticles could be entrapped more uniformly along the film profile because of more intensive evaporation
of silver droplets from the outer surface of the films on heating. 相似文献
19.
Agnieszka Król-Gracz Ewa Michalak Piotr M. Nowak Agnieszka Dyonizy 《Central European Journal of Chemistry》2011,9(6):982-989
This paper discusses the experimental results of the production of nanocolloidal silver using photoreduction method. Ultrafine
crystalline gelatine-stabilised aqueous suspensions of silver bromide were used as a substrate for the synthesis of silver
nanoparticles (Ag NPs). The influences of the reductant to substrate molar ratio, the medium’s pH, the type of the source of actinic radiation
and the time of exposure to the efficient production of the Ag NPs were studied. A typical reaction was suggested, which involves the photo-induced reduction of silver bromide nanocrystals
in the presence of ascorbic acid under specified physicochemical conditions. The properties of resultant silver particles
were examined using UV-Vis spectroscopy and Dynamic Light Scattering (DLS). In addition, Transmission Electron Microscopy
(TEM) was used for imaging the silver nanoparticle suspensions.
相似文献
20.
E. Ramírez-Meneses A. García-Murillo F. de J. Carrillo-Romo R. García-Alamilla P. Del Angel-Vicente J. Ramírez-Salgado P. Bartolo Pérez 《Journal of Sol-Gel Science and Technology》2009,52(2):267-275
Titania thin films were synthesized by sol–gel dip-coating method with metallic Ni nanoparticles synthesized separately from
an organometallic precursor Ni(COD)2 (COD = cycloocta-1,5-diene) in presence of 1,3-diaminopropane as a stabilizer. Titania was obtained from a titanium isopropoxide
precursor solution in presence of acetic acid. A Ni/TiO2 sol system was used to coat glass substrate spheres (6, 4 and 3 mm diameter sizes), and further heat treatment at 400 °C
was carried out to promote the crystallization of titania. XRD analysis of the TiO2 films revealed the crystallization of the anatase phase. Transmission Electron Microscopy (TEM) and High Resolution TEM studies
of Ni nanoparticles before mixing with the TiO2 solution revealed the formation of Ni nanostructures with an average size of 5–10 nm. High-angle annular dark-field images
of the Ni/TiO2 system revealed well-dispersed Ni nanoparticles supported on TiO2 and confirmed by AFM analysis. The photocatalytic activity of the Ni/TiO2 films was evaluated in hydrogen evolution from the decomposition of ethanol using a mercury lamp for UV light irradiation.
Titania films in presence of Ni nanoparticles show higher efficiency in their photocatalytic properties in comparison with
TiO2. 相似文献