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1.
Use of nanotechnology in biological systems by the synthesis of metallic nanoparticles is a burning area of research in recent times. In the present investigation, aqueous extract of Andrographis paniculata was used to produce silver nanoparticles by reduction of silver nitrate. It was noted that the synthesizing process was quite rapid and silver nanoparticles form within minutes of silver ions coming in contact with plant extract. UV-Vis spectrum of the aqueous medium containing silver ions indicated a peak at 432 nm corresponding to the plasmon absorbance of the silver nanoparticles. Fourier transform infrared spectroscopic analysis of the silver nanoparticles showed the presence of proteins that might be acting as capping agents around the nanoparticles. From scanning electron microscopy analysis, the size of the silver nanoparticles was measured and it was found that the average size was between 40 and 60 nm. Furthermore, the antibacterial activity of synthesized silver nanoparticles exhibited effective inhibition zones against seven bacterial strains tested. Among the bacteria tested Pseudomonas aeruginosa was found to be most susceptible to the silver nanoparticles. Phytochemical screening of the plant extract indicated the presence of alkaloids, flavonoids, amino acids, saponins, tannins, and terpenoids. 相似文献
2.
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
3.
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
4.
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
5.
Guowu Zhan Jiale Huang Liqin Lin Wenshuang Lin Kamana Emmanuel Qingbiao Li 《Journal of nanoparticle research》2011,13(10):4957-4968
In this study, biogenic fabrication of gold nanoparticles (AuNPs), respectively, by Cacumen Platycladi leaf extract and the simulation of its active components were thoroughly investigated. The simulated solution was prepared
based on components measurement and Fourier-transform infrared spectroscopy analysis of Cacumen Platycladi leaf extract before and after reaction. Several analytic methods such as UV–Vis spectrophotometry, X-ray diffraction, transmission
electron microscopy, and thermogravimetric study were adopted to characterize the AuNPs. The results showed that flavonoid
and reducing sugar were the main reductive and protective components in the extract vital in the biosynthesis of the AuNPs.
In addition, pH of the reaction solution was proved to be the most significant factor upon the synthesis process. The bioreduction
mechanism of chloroaurate ions and the formation mechanism of AuNPs were also discussed. To the best of our knowledge, this
is the first report on plausible elucidation of the biosynthetic mechanism through comparative study between a plant extract
and its simulated solution. 相似文献
6.
K. Govindaraju S. Tamilselvan V. Kiruthiga G. Singaravelu 《Journal of nanoparticle research》2011,13(12):6377-6388
Antiviral assays of chemically and biologically synthesized silver nanoparticles were made against BmNPV (Bombyx mori Nuclear Polyhedrosis Virus). Reduction of silver ions by sodium citrate and Spirulina platensis led to the formation of spherical silver nanoparticles of 40–60 and 7–16 nm size. Single cell protein (Spirulina platensis)-synthesized silver nanoparticles showed the strongest antiviral activity. Immunological studies made on the silkworm Bombyx mori disclosed that a significant increase in the total hemocyte count and differential hemocyte count due to S. platensis-synthesized silver nanoparticles supplementation. Improvement in the defense mechanism was noticed from the strengthened
peritrophic membrane of the digestive tract and the increased total protein. Overall, the results presented illustrate that
single cell protein-synthesized silver nanoparticles supplementation is effective in controlling viral-borne diseases of the
silkworm. 相似文献
7.
P. K. Khanna Deepti Kulkarni Rupinder K. Beri 《Journal of nanoparticle research》2008,10(6):1059-1062
Reduction of silver myristate (AgMy) under mild thermal reaction conditions in a dipolar aprotic solvent i.e. N, N-dimethylformamide (DMF) has been carried out. UV–visible absorption measurements of dried and re-dispersible brown flocculants
showed broad features of surface plasmon resonance (SPR) due to silver nanoparticles. The freshly isolated particles showed
absorption bands at 414 and 485 nm, respectively, due to inter-particle coupling or clustering of silver ions and silver atoms.
X-ray diffraction (XRD) pattern of fcc zero-valent silver resulted in crystallite size of about 10 nm. Scanning electron microscopy
(SEM) revealed formation of rod shaped silver with increasing reaction temperature. Thermal analysis (TGA) showed about 10%
weight loss due to organic capping. 相似文献
8.
Guadalupe Valverde-Aguilar Jorge A. García-Macedo Víctor M. Rentería-Tapia Raúl W. Gómez Manuel Quintana-García 《Journal of nanoparticle research》2011,13(10):4613-4622
Hexagonal mesostructured films containing silver ions were obtained by sol–gel method. Brij 58 was used to produce channels
into the film, which house these ions. The films were exposure to UV radiation to produced silver metallic nanoparticles.
The presence of the metallic nanoparticles was determined by infrared spectroscopy and optical absorption. Besides, these
nanoparticles and core–shell structures of silver–silver oxide nanoparticles were identified by high-resolution transmission
electronic microscopy. From these measurements, the obtained size range for silver nanoparticles was 6.1 nm. The absorption
spectrum located at 440 nm was modelled and well fitted with the Gans theory considering refractive index higher than the
one coming from host matrix. This index is explained because the silver oxide shell modifies the local surrounding medium
of the metallic nanoparticles. 相似文献
9.
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
10.
The facile biogenic synthesis of silver nanoparticles was done using avocado seed aqueous extract and silver salt. Avocado seed aqueous extract was used as an active biomolecule for in situ fabrication of self-assembled silver nanoparticles. This green approach to the mechanism for the formation of uniform sized silver nanoparticles was studied by ultraviolet-visible spectroscopy, field emission scanning electron microscopy and Fourier transform infrared spectroscopy. The effect of incubation time, concentration of silver nitrate, and avocado seed extract concentrations in the synthesis of silver nanoparticle was studied. Spectral splitting in the visible region with the generation of a new plasmon resonance band resulted with concurrent increase in the concentration of phytochemicals and reaction time during the synthesis of particles was observed. This was due to the chemisorption of phytochemicals accompanied by a charge-transfer transition, which may be responsible for the organization and self-assembly of nanoparticles. The phytochemicals present in the extract acted as a reducing agent and simultaneously fabricating the nanoparticles with the phenolics and sugar compounds. The antibrowning and antibacterial activity of silver nanoparticles were tested and could be exploited for their use in food packaging and preservation. 相似文献
11.
Formation and aggregation of photolytic silver nanoparticles at the surface of silver salt of carboxymethylcellulose films (CMCAg films) have been investigated. Detailed X-ray photoelectron spectroscopy (XPS) study and field emission type scanning electron microscopy (FE-SEM) observation have been carried out to characterize silver nanoparticles at the film surface. When the CMCAg films were irradiated with UV light in wet air at room temperature for 30–60 min, silver nanoparticles of ca. 10 nm size were formed at the irradiated surface. According to the FE-SEM observation, the growth of the particle diameter and aggregation of nanoparticles took place after prolonged irradiation, and finally, the irradiated side of the film surface was densely covered with the silver nanoparticles of ca. 35 nm size. Chemical composition analysis by the XPS measurements has confirmed the increase in the atomic concentration of silver with irradiation time. It is suggested that silver atoms and clusters can move in the film and precipitate at the irradiated surface. 相似文献
12.
V. N. Bagratashvili N. V. Minaev A. A. Rybaltovsky A. O. Rybaltovsky S. I. Tsypina V. Ya. Panchenko Yu. S. Zavorotny 《Laser Physics》2010,20(1):139-143
The fabrication of photoand thermostable periodic structures from silver nanoparticles in polymer plates (cross-linked oligourethanemethacrylate
impregnated with silver precursors Ag(hfac) and Ag(fod) dissolved in the supercritical carbon dioxide) is studied. The process
is based on the local (depending on the irradiated spot size) photochemical decomposition of the silver precursors in the
polymer matrix that initiates the atomic aggregation and creation of silver nanoparticles with the plasmon resonance in absorption
in the spectral range 420–430 nm. The third-harmonic radiation of a Nd:YAG laser (355 nm) and the Kr+-laser (521 nm) radiation are employed for the recording of periodic structures with submillimeter and micron resolutions.
The photosensitivity of the polymer matrices impregnated with the silver precursors to the UV and visible radiation is discussed. 相似文献
13.
N. M. Lyadov A. I. Gumarov V. F. Valeev V. I. Nuzhdin V. A. Shustov V. V. Bazarov I. A. Faizrakhmanov 《Technical Physics》2016,61(8):1237-1243
Thin (about 270 nm) nanocrystalline films of zinc oxide (ZnO) are obtained on quartz substrates using ion sputtering and irradiated with Ag+ ions at an energy of 30 keV and relatively high fluences at ion current densities of 4, 8, and 12 µA/cm2. The X-ray analysis, scanning electron microscopy, and optical spectroscopy are used to study the effect of irradiation dose and ion current density on the structural modification and optical properties of the ZnO films. Nontrivial dependences of the structural and optical parameters of the films on the ion irradiation regimes are due to radiation heating and film sputtering under the action of the ion beam, diffusion of impurity, formation of silver nanoparticles in the irradiated layer at high implantation fluences, and the diffusion of implanted impurity at relatively high ion current densities. 相似文献
14.
R.M. Tilaki A. Iraji zad S.M. Mahdavi 《Applied Physics A: Materials Science & Processing》2006,84(1-2):215-219
We studied the effects of the surrounding liquid environment on the size and optical properties of silver nanoparticles prepared by laser ablation by a pulsed Nd:YAG laser operated at 1064 nm. The silver targets used were kept in acetone, water and ethanol. TEM observations and optical extinction were employed for characterization of particle size, shape and optical properties, respectively. Nano silver in acetone showed a narrow size distribution with a mean size of 5 nm and the colloidal solution was stable. In deionised water a rather narrow size distribution with a mean size of 13 nm was observed and nanoparticles were precipitated slowly after about two weeks. In ethanol, a broadening in size distribution and optical extinction spectra was observed. Silver nanoparticles in ethanol with a mean size of 22 nm were completely precipitated after 48 h. In acetone, deionised water and ethanol, the wavelengths of maximum optical extinction are 399, 405 and 411 nm respectively, which is attributed to increasing the size of the nanoparticles. Growth, aggregation and precipitation mechanisms were related to the dipole moment of the surrounding molecules in order to clarify the difference in size, optical properties and stability of the nanoparticles. PACS 79.20.Ds; 81.07.-b; 61.46.+w 相似文献
15.
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
16.
Marcus Koch Silke Kiefer Christian Cavelius Annette Kraegeloh 《Journal of nanoparticle research》2012,14(2):646-11
For a detailed analysis of the biological effects of silver nanoparticles, discrimination between effects related to the nano-scale
size of the particles and effects of released silver ions is required. Silver ions are either present in the initial particle
dispersion or released by the nanoparticles over time. The aim of this study is to monitor the free silver ion activity {Ag+} in the presence of silver nanoparticles using a silver ion selective electrode. Therefore, silver in the form of silver
nanoparticles, 4.2 ± 1.4 nm and 2–30 nm in size, or silver nitrate was added to cell culture media in the absence or presence
of A549 cells as a model for human type II alveolar epithelial cells. The free silver ion activity measured after the addition
of silver nanoparticles was determined by the initial ionic silver content. The p {Ag+} values indicated that the cell culture media decrease the free silver ion activity due to binding of silver ions by constituents
of the media. In the presence of A549 cells, the free silver ion activity was further reduced. The morphology of A549 cells,
cultivated in DME medium containing 9.1% (v/v) FBS, was affected by adding AgNO3 at concentrations of ≥30 μM after 24 h. In comparison, silver nanoparticles up to a concentration of 200 μM Ag did not affect
cellular morphology. Our experiments indicate that the effect of silver nanoparticles is mainly mediated by silver ions. An
effect of silver on cellular morphology was observed at p {Ag+} ≤ 9.2. 相似文献
17.
Poly(methacrylic acid) (PMA) stabilized silver nanoparticles (Ag NPs), also used in the surface modification of clothing fibers, were fabricated via chemical reduction processes under UV irradiation. To obtain an uniform size distribution it has been designed a new “two-step” process which employs two different UV radiation densities in order to control the kinetics of NPs nucleation. The as produced nanoparticles were characterized by UV-vis absorption spectroscopy and TEM microscopy. The results show the reduction of the Ag ions and the nanoparticles nucleation in the first step. In the second step, the final Ag NPs size distribution is controlled through a quick cross-linking of the PMA that freezes out any further modification. A narrow size distribution with more than 80% NPs smaller than 10 nm and none larger than 25 nm was obtained and the long-term stability (one month) of the colloidal solution was verified. 相似文献
18.
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
19.
Ramasamy Rajesh Kumar Krishnamurthy Poornima Priyadharsani Kaliannan Thamaraiselvi 《Journal of nanoparticle research》2012,14(5):860
In this study, an environmental friendly process for the synthesis of silver nanoparticles (AgNPs) using a fungus Aspergillus tamarii has been investigated. The process of silver ion reduction by the fungal extracellular filtrate was spontaneous which lead
to the development of an easy process for synthesis of silver nanoparticles. The AgNPs formed were characterized using UV–Visible
spectrum, FTIR, and SEM. The results revealed that silver ions reduction by the fungal extracellular filtrate started at 420 nm
after 0.5 h of incubation time. The FTIR peaks were observed at 1393, 1820, 2727, and 3545 cm−1. The SEM result showed the distribution of spherical AgNPs ranging from 25 to 50 nm. 相似文献
20.
D. Mohanta G.A. Ahmed A. Choudhury F. Singh D.K. Avasthi 《Journal of nanoparticle research》2006,8(5):645-652
ZnS:Mn nanoparticles of size variation 11–17 nm were synthesized by a simple and inexpensive chemical method and confirmed by transmission electron microscopy (TEM). Presuming electronic energy loss (S
e>S
n, S
n being nuclear energy loss) to be the dominant phenomenon, they were irradiated by 80-MeV energetic oxygen ions with fluence of 1011 to 1013 ions/cm2. Photoluminescence (PL) spectra revealed three major emission bands ~445 nm, ~582 nm and ~706 nm; which are ascribed to D–A pair transition, Mn emission and surface state led fluorescence activation. The recovery of Mn emission and tunable surface state emission have been observed with ion fluence variation. Infra-red (IR) spectra of irradiated samples show great extent of oscillation with respect to amplitude due to ion fluence variation however, phonon energy (~98 MeV) remains unchanged. The possible applications of these modified properties in nanophotonics are also highlighted. 相似文献