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metal-nanoparticle
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Molecular dynamics simulation of manipulation of metallic nanoclusters on stepped surfaces
, Article Central European Journal of Physics ; Volume 9, Issue 2 , 2011 , pp 454-465 ; 1644-3608 ; Meghdari, A. (Ali) ; Jalili, N. (Nader) ; Amiri, F. (Farshid) ; Sharif University of Technology
Abstract
Molecular dynamics simulations are carried out to investigate the manipulation of metallic clusters on stepped surfaces. Five surface forms are considered in the simulations. The system parts are made of pure transition metals and Sutton-Chen many-body potential is used as interatomic potential. The conditions which are subjected to change in the tests include: materials used for particles and substrate, and surface step conditions. In addition to qualitative observations, two criteria which represent the particle deformation and substrate abrasion are utilized as evaluation tools and are computed for each case. Simulation results show the effect of the aforementioned working conditions on...
Molecular dynamics simulation of manipulation of metallic nanoclusters on double-layer substrates [electronic resource]
, Article Physica E: Low-dimensional Systems and Nanostructures ; 2010, Vol. 42, No. 9, pp. 2364-2374 ; Meghdari, Ali ; Jalili, Nader ; Amiri, Farshid ; Sharif University of Technology
Abstract
Molecular dynamics simulations are carried out to investigate the manipulation of metallic clusters on double-layer surfaces. The system parts are made of transition metals. The conditions which are subjected to change in the tests are material combinations for cluster, main substrate and lubricant layer (adlayer). In addition to qualitative observations, two criteria which represent the particle deformation and substrate abrasion are utilized as evaluation tools and are computed for each case. Obtaining this sort of knowledge is highly beneficial for further experiments in order to be able to plan the conditions and routines, which guarantee better success in the manipulation process
Nanoscale phase behavior on flat and curved membranes
, Article Nanotechnology ; Vol. 25, issue. 50 , Dec , 2014 ; Bahadori, A ; Ott, D ; Kyrsting, A ; Reihani, S. N. S ; Bendix, P. M ; Sharif University of Technology
Abstract
The diverse physical properties of membranes play a critical role in many membrane associated biological processes. Proteins responsible for membrane transport can be affected by the lateral membrane order and lateral segregation of proteins is often controlled by the preference of certain membrane anchors for membrane phases having a physically ordered state. The dynamic properties of coexisting membrane phases are often studied by investigating their thermal behavior. Optical trapping of gold nanoparticles is a useful tool to generate local phase transitions in membranes. The high local temperatures surrounding an irradiated gold nanoparticle can be used to melt a part of a giant...
A sensitive and selective colorimetric method for detection of copper ions based on anti-aggregation of unmodified gold nanoparticles
, Article Talanta ; Vol. 129, issue , 2014 , pp. 227-232 ; ISSN: 00399140 ; Abbasi-Moayed, S ; Sharif University of Technology
Abstract
A highly sensitive and selective colorimetric method for detection of copper ions, based on anti-aggregation of D-penicillamine (D-PC) induced aggregated gold nanoparticles (AuNPs) was developed. Copper ions can hinder the aggregation of AuNPs induced by D-PC, through formation of mixed-valence complex with D-PC that is a selective copper chelator. In the presence of a fixed amount of D-PC, the aggregation of AuNPs decreases with increasing concentrations of Cu2+ along with a color change from blue to red in AuNPs solution and an increase in the absorption ratio (A520/A 650). Under the optimum experimental conditions (pH 7, [AuNPs] =3.0 nmol L-1 and [NaCl]=25 mmol L-1), a linear calibration...
Fabrication localized surface plasmon resonance sensor chip of gold nanoparticles and detection lipase-osmolytes interaction
, Article Applied Surface Science ; Vol. 314, issue , 2014 , Pages 138-144 ; ISSN: 01694332 ; Hoornam, S ; Vesaghi, M. A ; Ranjbar, B ; Azizi, A ; Mobasheri, H ; Sharif University of Technology
Abstract
Co-deposition of RF-sputtering and RF-PECVD from acetylene gas and Au target were used to prepare sensor chip of gold nanoparticles (Au NPs). Deposition conditions were optimized to reach a Localized Surface Plasmon Resonance (LSPR) sensor chip of Au NPs with particle size less than 10 nm. The RF power was set at 180 W and the initial gas pressure was set at 0.035 mbar. Transmission Electron Microscopy (TEM) images and Atomic Force Microscopy (AFM) data were used to investigate particles size and surface morphology of LSPR sensor chip. The Au and C content of the LSPR sensor chip of Au NPs was obtained from X-ray photoelectron spectroscopy (XPS). The hydrogenated amorphous carbon (a-C:H)...
DNA impedance biosensor for detection of cancer, TP53 gene mutation, based on gold nanoparticles/aligned carbon nanotubes modified electrode
, Article Analytica Chimica Acta ; Vol. 836, issue , July , 2014 , p. 34-44 ; ISSN: 00032670 ; Afshar, A ; Dolati, M ; Dolati, A ; Sharif University of Technology
Abstract
For the first time, a new platform based on electrochemical growth of Au nanoparticles on aligned multi-walled carbon nanotubes (A-MWCNT) was developed for sensitive lable-free DNA detection of the TP53 gene mutation, one of the most popular genes in cancer research. Electrochemical impedance spectroscopy (EIS) was used to monitor the sequence-specific DNA hybridization events related to TP53 gene. Compared to the bare Ta or MWCNT/Ta electrodes, the synergistic interactions of vertically aligned MWCNT array and gold nanoparticles at modified electrode could improve the density of the probe DNA attachment and resulting the sensitivity of the DNA sensor greatly. Using EIS, over the extended...
A second-order advantage achieved with the aid of gold nanoparticle catalytic activity. Determination of nitrophenol isomers in binary mixtures
, Article Analytical Methods ; Vol. 6, issue. 9 , Feb , 2014 , pp. 3056-3064 ; ISSN: 17599660 ; Abdollahi, H ; Hormozi-Nezhad, M. R ; Sharif University of Technology
Abstract
A novel, simple and rapid spectrophotometric method for the determination of nitrophenol (NP) isomer mixtures based on the catalytic activity of gold nanoparticles is described. Gold nanoparticle (∼13 nm) solution was used to catalyze the reduction of NP isomers to aminophenols with an excess amount of NaBH4. The second-order data were obtained by spectrophotometrically monitoring the reduction process of NP isomers. So, multivariate curve resolution optimized by alternative least squares (MCR-ALS) was used to analyze such data. MCR-ALS, an appropriate second-order method, can exploit the so-called 'second order advantage' (the ability to determine in the presence of uncalibrated...
Rapid and simultaneous determination of tetracycline and cefixime antibiotics by mean of gold nanoparticles-screen printed gold electrode and chemometrics tools
, Article Measurement: Journal of the International Measurement Confederation ; Vol. 47, Issue. 1 , 2014 , pp. 145-149 ; ISSN: 02632241 ; Mani-Varnosfaderani, A ; Sharif University of Technology
Abstract
The screen-printed gold electrode (SPGE) modified with the formation of self-assembly monolayer (SAM) of cysteine (Cys) on gold-nanoparticles (Au nano) was utilized for rapid and simultaneous determination of tetracycline and cefixime antibiotics by square wave voltammetry (SWV). Electrochemical investigation and characterization of the modified electrode was achieved using cyclic voltammetry (CV) and scanning electron microscopy (SEM). A principal component artificial neural network (PCANN) with three layer back-propagation network was utilized for the analysis of the voltammogram data. It is possible to simultaneously determine the tetracycline and cefixime concentrations in the ranges of...
Pd-Au nanoparticle decorated carbon nanotube as a sensing layer on the surface of glassy carbon electrode for electrochemical determination of ceftazidime
, Article Materials Science and Engineering C ; Vol. 34, issue. 1 , 2014 , pp. 318-325 ; ISSN: 09284931 ; Salimian, R ; Rastgar, S ; Sharif University of Technology
Abstract
A simple electrodeposition method is employed to construct a thin film modifier of palladium-gold nanoparticles (Pd-AuNPs) decorated multi-walled carbon nanotube (MWCNT) on the surface of glassy carbon electrode (GCE). Morphology and property of Pd-AuNPs-MWCNT have been examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Electrochemical performance of Pd-AuNPs-MWCNT/GCE for detection of ceftazidime (CFZ) has been investigated by cyclic voltammetry (CV). This nanostructured film modified electrode effectively exhibited enhanced properties for detection of ceftazidime (CFZ). The effects of various experimental variables such as, the amount of casted MWCNT,...
Nickel hydroxide nanoparticles-reduced graphene oxide nanosheets film: Layer-by-layer electrochemical preparation, characterization and rifampicin sensory application
, Article Talanta ; Vol. 119 , 2014 , pp. 156-163 ; ISSN: 00399140 ; Shahrokhian, S ; Sharif University of Technology
Abstract
Electrochemical deposition, as a well-controlled synthesis procedure, has been used for subsequently layer-by-layer preparation of nickel hydroxide nanoparticle-reduced graphene oxide nanosheets (Ni(OH)2-RGO) on a graphene oxide (GO) film pre-cast on a glassy carbon electrode surface. The surface morphology and nature of the nano-hybrid film (Ni(OH)2-RGO) was thoroughly characterized by scanning electron and atomic force microscopy, spectroscopy and electrochemical techniques. The modified electrode appeared as an effective electro-catalytic model for analysis of rifampicin (RIF) by using linear sweep voltammetry (LSV). The prepared modified electrode exhibited a distinctly higher activity...
Carbon-Pt nanoparticles modified TiO 2 nanotubes for simultaneous detection of dopamine and uric acid
, Article Journal of Nanoscience and Nanotechnology ; Volume 11, Issue 8 , 2011 , Pages 6668-6675 ; 15334880 (ISSN) ; Luo, S ; Yang, L ; Mahshid, S. S ; Askari, M ; Dolati, A ; Cai, Q ; Sharif University of Technology
Abstract
The present work describes sensing application of modified TiO 2 nanotubes having carbon-Pt nanoparticles for simultaneous detection of dopamine and uric acid. The TiO 2 nanotubes electrode was prepared using anodizing method, followed by electrodeposition of Pt nanoparticles onto the tubes. Carbon was deposited by decomposition of polyethylene glycol in a tube furnace to improve the conductivity. The C-Pt-TiO 2 nanotubes modified electrode was characterized by cyclic voltam-metry and differential pulse voltammetry methods. The modified electrode displayed high sensitivity towards the oxidation of dopamine and uric acid in a phosphate buffer solution (pH 7.00). The electro-oxidation currents...
All optical switch based on Fano resonance in metal nanocomposite photonic crystals
, Article Optics Communications ; Volume 284, Issue 8 , 2011 , Pages 2230-2235 ; 00304018 (ISSN) ; Malek Mohammad, M ; Khorasani, S ; Sharif University of Technology
Abstract
We investigate the potential of plasmonic resonance in metal nanocomposite materials for the design of photonic crystal all optical switches by numerical methods. We study the absorption effect of the plasmonic resonance on the Fano resonances of one dimensional photonic crystal slabs covered by a metal nanocomposite layer. It is shown that the absorption reduces the contrast of the Fano resonances. However, for adequate metal nanoparticle concentrations it is possible to achieve both sufficiently sharp Fano resonance and strong Kerr nonlinearity, which provides a suitable condition for the design of high contrast and low threshold switches
Fe 50Co 50 nanoparticles via self-propagating high-temperature synthesis during milling
, Article Powder Technology ; Volume 208, Issue 3 , 2011 , Pages 623-627 ; 00325910 (ISSN) ; Yourdkhani, A ; Koohestani, H ; Sadrnezhaad, S. K ; Asmatulu, R ; Sharif University of Technology
Abstract
Self-propagating exothermic reactions during mechanical milling of FeCl 3/CoCl 2 mixture together with sodium seeds resulted in formation of Fe 50Co 50 nanoparticles. Highly exothermic reactions resulted in temperature raise and formation of Fe 50Co 50 phase within the first 5min; however Fe 50Co 50 single-phase was obtained after 30min of milling. The products were characterized by XRD, SEM, EDS, TEM and VSM. Obtained results showed that both milling time and NaCl salt matrix affected the size, morphology, microstructure and magnetic properties of the produced particles
Compound Hertzian chain model for copper-carbon nanocomposites' absorption spectrum
, Article Micro and Nano Letters ; Volume 6, Issue 4 , 2011 , Pages 277-279 ; 17500443 (ISSN) ; Hosseini, M ; Saeedi, S ; Moftakharzadeh, A ; Vesaghi, M. A ; Fardmanesh, M ; Sharif University of Technology
Abstract
The infrared range optical absorption mechanism of carbon-copper composite thin layer coated on the diamond-like carbon buffer layer has been investigated. By consideration of weak interactions between copper nanoparticles in their network, optical absorption is modelled using their coherent dipole behaviour induced by the electromagnetic radiation. The copper nanoparticles in the bulk of carbon are assumed as a chain of plasmonic dipoles, which have coupling resonance. Considering nearest neighbour interactions for this metallic nanoparticles, surface plasmon resonance frequency (ω 0) and coupled plasmon resonance frequency (ω 1) have been computed. The damping rate against wavelength is...
Molecular dynamics simulation of manipulation of metallic nanoclusters on stepped surfaces
, Article Central European Journal of Physics ; Volume 9, Issue 2 , 2011 , Pages 454-465 ; 18951082 (ISSN) ; Meghdari, A ; Jalili, N ; Amiri, F ; Sharif University of Technology
Abstract
Molecular dynamics simulations are carried out to investigate the manipulation of metallic clusters on stepped surfaces. Five surface forms are considered in the simulations. The system parts are made of pure transition metals and Sutton-Chen many-body potential is used as interatomic potential. The conditions which are subjected to change in the tests include: materials used for particles and substrate, and surface step conditions. In addition to qualitative observations, two criteria which represent the particle deformation and substrate abrasion are utilized as evaluation tools and are computed for each case. Simulation results show the effect of the aforementioned working conditions on...
Antibacterial silver nanoparticles in polyvinyl alcohol/sodium alginate blend produced by gamma irradiation
, Article International Journal of Biological Macromolecules ; Volume 80 , 2015 , Pages 170-176 ; 01418130 (ISSN) ; Frounchi, M ; Dadbin, S ; Sharif University of Technology
Abstract
Polyvinyl alcohol/sodium alginate/nano silver (PVA/SA/Ag) composite films were made by solution casting method. Gamma irradiation was used to synthesize silver nanoparticles in situ via reduction of silver nitrate without using harmful chemical agents for biomedical applications. UV-vis and XRD results demonstrated that spherical silver nanoparticles were produced even at low irradiation dose of 5. kGy. By increasing irradiation dose, more nanoparticles were synthesized while no PVA hydrogel was formed up to 15. kGy. Also the size of nanoparticles was reduced with increasing gamma dose evidenced by higher release rate of silver nanoparticles in lukewarm water and SEM images. Comparing SEM...
Rheology and colloidal structure of silver nanoparticles dispersed in diethylene glycol
, Article Powder Technology ; Volume 197, Issue 1-2 , 2010 , Pages 49-53 ; 00325910 (ISSN) ; Guenther, B. H ; Sharif University of Technology
Abstract
Rheological behavior of agglomerated silver nanoparticles (~ 40 nm) suspended in diethylene glycol over a wide range of volumetric solids concentrations (φ{symbol} = 0.11-4.38%) was studied. The nanoparticle suspensions generally exhibited a yield pseudoplastic behavior. Bingham plastic, Herschel-Bulkley and Casson models were used to evaluate the shear stress-shear rate dependency. Analyzing the effect of silver concentrations on the yield stress and viscosity of the suspensions followed an exponential form, revealing an increase in the degree of interparticle interactions with increasing solid concentrations. Fractal dimension (Df) was estimated from the suspension yield stress and...
α-Arylation of oxindoles using recyclable metal oxide ferrite nanoparticles: Comparison between the catalytic activities of nickel, cobalt and copper ferrite nanoparticles
, Article Catalysis Communications ; Volume 75 , 2016 , Pages 37-41 ; 15667367 (ISSN) ; Tavakoli, G ; Latifi, F ; Saeednia, B ; Sharif University of Technology
Elsevier
Abstract
Three different spinel metal oxide catalytic systems including NiFe2O4, CuFe2O4 and CoFe2O4 were synthesized using co-precipitation technique and their catalytic activities were compared to each other in α-arylation of oxindole derivatives under the optimized reaction conditions. Both nickel ferrite and copper ferrite magnetic nanoparticles show approximately the same behavior in these reactions but cobalt ferrite ones indicate slightly different properties and were not as good as the other two catalysts. These superparamagnetic catalysts allowed that α-arylation of different types of oxindoles will occur in high yields under mild conditions and at very short times
Development of a novel method for determination of mercury based on its inhibitory effect on horseradish peroxidase activity followed by monitoring the surface plasmon resonance peak of gold nanoparticles
, Article Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy ; Volume 153 , 2016 , Pages 709-713 ; 13861425 (ISSN) ; Haji Shabani, A. M ; Dadfarnia, S ; Rohani Moghadam, M. R ; Hormozi Nezhad, M. R ; Sharif University of Technology
Elsevier
Abstract
A highly sensitive and simple indirect spectrophotometric method has been developed for the determination of trace amounts of inorganic mercury (Hg2 +) in aqueous media. The method is based on the inhibitory effect of Hg2 + on the activity of horseradish peroxidase (HRP) in the oxidation of ascorbic acid by hydrogen peroxide followed by the reduction of Au3 + to Au-NPs by unreacted ascorbic acid and the measurement of the absorbance of localized surface plasmon resonance (LSPR) peak of gold nanoparticles (at 530 nm) which is directly proportional to the concentration of Hg2 +. Under the optimum conditions, the calibration curve was linear in the concentration range of 1-220 ng mL- 1. Limits...
Multi-response optimization followed by multivariate calibration for simultaneous determination of carcinogenic polycyclic aromatic hydrocarbons in environmental samples using gold nanoparticles
, Article RSC Advances ; Volume 6, Issue 106 , 2016 , Pages 104254-104264 ; 20462069 (ISSN) ; Parastar, H ; Hormozi Nezhad, M. R ; Sharif University of Technology
Royal Society of Chemistry
Abstract
In this study, a multivariate-based strategy was developed for simultaneous determination of thirteen carcinogenic polycyclic aromatic hydrocarbons (PAHs) in water samples using gold nanoparticles (AuNPs) as solid-phase extraction (SPE) sorbent combined with gas chromatography (GC). The extraction technique is based on the strong affinity between citrate-capped AuNPs and PAHs. Furthermore, characterization of AuNPs was performed by UV-vis spectroscopy and transmission electron microscopy (TEM) techniques. A rotatable central composite design (CCD) combined with multiple linear regression (MLR) was used for designing the extraction procedure and developing models using the GC peak areas of 13...