Progress on Numerical Modeling of the Dispersion of Ceramic Nanoparticles During Ultrasonic Processing and Solidification of Al-Based Nanocomposites

Science.gov (United States)

Zhang, Daojie; Nastac, Laurentiu

2016-12-01

In present study, 6061- and A356-based nano-composites are fabricated by using the ultrasonic stirring technology (UST) in a coreless induction furnace. SiC nanoparticles are used as the reinforcement. Nanoparticles are added into the molten metal and then dispersed by ultrasonic cavitation and acoustic streaming assisted by electromagnetic stirring. The applied UST parameters in the current experiments are used to validate a recently developed magneto-hydro-dynamics (MHD) model, which is capable of modeling the cavitation and nanoparticle dispersion during UST processing. The MHD model accounts for turbulent fluid flow, heat transfer and solidification, and electromagnetic field, as well as the complex interaction between the nanoparticles and both the molten and solidified alloys by using ANSYS Maxwell and ANSYS Fluent. Molecular dynamics (MD) simulations are conducted to analyze the complex interactions between the nanoparticle and the liquid/solid interface. The current modeling results demonstrate that a strong flow can disperse the nanoparticles relatively well during molten metal and solidification processes. MD simulation results prove that ultrafine particles (10 nm) will be engulfed by the solidification front instead of being pushed, which is beneficial for nano-dispersion.

Synthesis and Characterization of Metal Sulfides Nanoparticles/Poly(methyl methacrylate) Nanocomposites

OpenAIRE

Ajibade, Peter A.; Mbese, Johannes Z.

2014-01-01

Metal sulfides nanoparticles in poly(methyl methacrylate) matrices were prepared and characterized by infrared spectroscopy, thermogravimetric analysis, powder X-ray diffraction, scanning electron microscope (SEM), and transmission electron microscope (TEM). The FTIR confirms the dispersion of the nanoparticles in PMMA matrices with the C=O and C–O–C bonds of the PMMA shifting slightly which may be attributed to the interactions between the nanoparticles and PMMA. The ZnS nanoparticles in PMM...

Unique coexistence of dispersion stability and nanoparticle chemisorption in alkylamine/alkylacid encapsulated silver nanocolloids.

Science.gov (United States)

Aoshima, Keisuke; Hirakawa, Yuya; Togashi, Takanari; Kurihara, Masato; Arai, Shunto; Hasegawa, Tatsuo

2018-04-17

Surface encapsulation of metal nanoparticles (NPs) is fundamental to achieve sufficient dispersion stability of metal nanocolloids, or metal nanoink. However, the feature is incompatible with surface reactive nature of the metal NPs, although these features are both essential to realizing the functional applications into printed electronics technologies. Here we show that two different kinds of encapsulation for silver NPs (AgNPs) by alkylamine and alkylacid together are the key to achieve unique compatibility between the high dispersion stability as dense nanoclolloids and the AgNP chemisorption printing on activated patterned polymer surfaces. Advanced confocal dynamic light scattering study reveals that an additive trace amount of oleic acid is the critical parameter for controlling the dispersion and coagulative (or surface-reactive) characteristics of the silver nanocolloids. The composition of the disperse media is also important for obtaining highly concentrated but low-viscosity silver nanocolloids that show very stable dispersion. The results demonstrate that the high-resolution AgNP chemisorption printing is possible only by using unique silver nanocolloids composed of an exceptional balance of ligand formulation and dispersant composition.

Synthesis and purification of oxide nanoparticle dispersions by modified emulsion precipitation.

Science.gov (United States)

Shi, Jingyu; Verweij, Henk

2005-06-07

ZrO2 and Fe2O3 precursor nanoparticles are synthesized, well-dispersed in decane, via a modified emulsion precipitation (MEP) method. This method starts with preparing two thermostable water-in-oil (w/o) emulsions with nonylphenol tetra(ethylene glycol) ether (Arkopal-40) as the main surfactant, didodecyldimethylammonium bromide (DiDAB) as the cosurfactant, decane as the continuous oil phase, and either a metal salt solution or a hexamethylenetetramine (HMTA) precipitation agent solution as the dispersed water phase. After mixing of the two emulsions, individual precursor particles are formed by precipitation in the confinement of the aqueous solution droplets. Excess water is removed by azeotropic distillation, and steric stabilization of the particles in the remaining oil medium is achieved with poly(octadecyl methacrylate) (PODMA), initially present dissolved in the oil phase. A purification process is conducted to remove the precipitation reaction byproduct and excess surfactants from the nanoparticle dispersions. Transmission electron microscopy (TEM) characterization shows that the ZrO2 and Fe2O3 precursor nanoparticles are both non-agglomerated, spherical, and have a narrow particle size distribution, centered at 4 nm in diameter. The precipitation from the dispersion of byproduct NH4Cl after water removal, and insoluble surfactant DiDAB after dilution with pure decane, is confirmed by X-ray diffraction (XRD). NMR results show that most of the oil-soluble surfactant Arkopal-40 can be removed from the dispersion by a 3x repeated dead-end pressure filtration process. It is shown that, after purification, the nanoparticle dispersions can be used for the preparation of homogeneous nanostructured coatings. The purification procedure as discussed provides guidelines for up-scaling the process and reuse of emulsifiers.

Synthesis of Pd and Rh metal nanoparticles in the interlayer space of organically modified montmorillonite

International Nuclear Information System (INIS)

Patel, Hasmukh A.; Bajaj, Hari C.; Jasra, Raksh Vir

2008-01-01

This study reports the synthesis of palladium and rhodium metal nanoparticles supported on montmorillonite (MMT) and partially organically modified MMT (POMM) using tetraamine palladium and hexaamine rhodium complex as precursor for palladium and rhodium respectively. The synthesized nanoparticles were characterized by powder X-ray diffraction PXRD and TEM. The PXRD study shows characteristic crystallographic planes for Pd and Rh metal and confirm the formation of metal nanoparticles in MMT and POMM. The TEM images reveal the effect of organic modification of MMT on decreasing particle size of Pd and Rh metal. The Pd and Rh metal nanoparticles are agglomerated in pristine MMT while nanoparticles are well dispersed in POMM. ICP-AES analysis was carried out to estimate quantitative amount of Pd and Rh metal in MMT and POMM

Nanoparticles of noble metals in the supergene zone

Science.gov (United States)

Zhmodik, S. M.; Kalinin, Yu. A.; Roslyakov, N. A.; Mironov, A. G.; Mikhlin, Yu. L.; Belyanin, D. K.; Nemirovskaya, N. A.; Spiridonov, A. M.; Nesterenko, G. V.; Airiyants, E. V.; Moroz, T. N.; Bul'bak, T. A.

2012-04-01

Formation of noble metal nanoparticles is related to various geological processes in the supergene zone. Dispersed mineral phases appear during weathering of rocks with active participation of microorganisms, formation of soil, in aqueous medium and atmosphere. Invisible gold and other noble metals are incorporated into oxides, hydroxides, and sulfides, as well as in dispersed organic and inorganic carbonic matter. Sulfide minerals that occur in bedrocks and ores unaltered by exogenic processes and in cementation zone are among the main concentrators of noble metal nanoparticles. The ability of gold particles to disaggregate is well-known and creates problems in technological and analytical practice. When Au and PGE nanoparticles and clusters occur, these problems are augmented because of their unusual reactions and physicochemical properties. The studied gold, magnetite, titanomagnetite and pyrite microspherules from cementation zone and clay minerals of laterites in Republic of Guinea widen the knowledge of their abundance and inferred formation conditions, in particular, in the contemporary supergene zone. Morphology and composition of micrometer-sized Au mineral spherules were studied with SEM and laser microprobe. The newly formed segregations of secondary gold on the surface of its residual grains were also an object of investigation. The character of such overgrowths is the most indicative for nanoparticles. The newly formed Au particles provide evidence for redistribution of ultradispersed gold during weathering. There are serious prerequisites to state that microorganisms substantially control unusual nano-sized microspherical morphology of gold particles in the supergene zone. This is supported by experiments indicating active absorption of gold by microorganisms and direct evidence for participation of Ralstonia metallidurans bacteria in the formation of peculiar corroded bacteriomorphic surface of gold grains. In addition, the areas enriched in carbon

Polymer-mediated synthesis of a nitrogen-doped carbon aerogel with highly dispersed Pt nanoparticles for enhanced electrocatalytic activity

International Nuclear Information System (INIS)

2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" data-affiliation=" (World Class University (WCU) Program of Chemical Convergence for Energy & Environment C2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" >Kim, Gil-Pyo; 2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" data-affiliation=" (World Class University (WCU) Program of Chemical Convergence for Energy & Environment C2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" >Lee, Minzae; Lee, Yoon Jae; 2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" data-affiliation=" (World Class University (WCU) Program of Chemical Convergence for Energy & Environment C2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" >Bae, Seongjun; 2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" data-affiliation=" (World Class University (WCU) Program of Chemical Convergence for Energy & Environment C2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" >Song, Hyeon Dong; Song, In Kyu; 2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" data-affiliation=" (World Class University (WCU) Program of Chemical Convergence for Energy & Environment C2E2, School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul 151-742 (Korea, Republic of))" >Yi, Jongheop

2016-01-01

Highlights: • Highly dispersed Pt nanoparticles on N-doped carbon aerogel were synthesized for ORR. • Poly(ethyleneimine) was used as nitrogen source and as nucleation sites for Pt. • Precise discussion were conducted to clarify the effect of poly(ethyleneimine). • High Pt dispersion and N-doping results in superior electrocatalytic activity. - Abstract: A simple chemical process for the direct synthesis of a nitrogen (N)-doped carbon aerogel (NCA) with highly dispersed Pt nanoparticles via a poly(ethyleneimine) (PEI)-assisted strategy is described. A resorcinol-formaldehyde (RF) gel was treated with water soluble cationic PEI, which mainly functions as an anchoring site for metal ions. The functionalized PEI chains on the surface of the RF gel resulted in the unique formation of chemical complexes, with PtCl 6 2− anchored to the RF gel, and subsequent homogeneous metal nanoparticle growth. The abundant amino groups containing PEI grafted to the RF gel also allowed the nitrogen atoms to be incorporated into the carbon framework, which can directly be converted into a NCA. The spherical Pt nanoparticles in the resulting material (Pt/NCA) were highly dispersed on the surface of the NCA without any evidenced of agglomeration, even after a thermal annealing at 900 °C. Compared with a Pt/CA synthesized by a conventional reduction method, the Pt/NCA showed enhanced electrochemical performance with a high electrochemically active surface area (191.1 cm 2 g −1 ) and electrocatalytic activity (V onset = 0.95 V vs. RHE) with respect to oxygen reduction. The superior electrocatalytic activities of the Pt/NCA can be attributed to the synergistic effect of the highly dispersed Pt nanoparticles and the N-doped carbon supports that were prepared using the PEI-assisted strategy. The findings reported herein suggest that the use of PEI can be effectively extended to broad applications that require the homogeneous deposition of metal nanoparticles.

Coulomb force directed single and binary assembly of nanoparticles from aqueous dispersions by AFM nanoxerography.

Science.gov (United States)

Palleau, Etienne; Sangeetha, Neralagatta M; Viau, Guillaume; Marty, Jean-Daniel; Ressier, Laurence

2011-05-24

We present a simple protocol to obtain versatile assemblies of nanoparticles from aqueous dispersions onto charge patterns written by atomic force microscopy, on a 100 nm thin film of polymethylmethacrylate spin-coated on silicon wafers. This protocol of nanoxerography uses a two-stage development involving incubation of the desired aqueous colloidal dispersion on charge patterns and subsequent immersion in an adequate water-soluble alcohol. The whole process takes only a few minutes. Numerical simulations of the evolution of the electric field generated by charge patterns in various solvents are done to resolve the mechanism by which nanoparticle assembly occurs. The generic nature of this protocol is demonstrated by constructing various assemblies of charged organic/inorganic/metallic (latex, silica, gold) nanoparticles of different sizes (3 to 100 nm) and surface functionalities from aqueous dispersions onto charge patterns of complex geometries. We also demonstrate that it is possible to construct a binary assembly of nanoparticles on a pattern made of positive and negative charges generated in a single charge writing step, by sequential developments in two aqueous dispersions of oppositely charged particles. This protocol literally extends the spectra of eligible colloids that can be assembled by nanoxerography and paves the way for building complex assemblies of nanoparticles on predefined areas of surfaces, which could be useful for the elaboration of nanoparticle-based functional devices.

Plasma Methods of Obtainment of Multifunctional Composite Materials, Dispersion-Hardened by Nanoparticles

Science.gov (United States)

Sizonenko, O. N.; Grigoryev, E. G.; Pristash, N. S.; Zaichenko, A. D.; Torpakov, A. S.; Lypian, Ye. V.; Tregub, V. A.; Zholnin, A. G.; Yudin, A. V.; Kovalenko, A. A.

2017-09-01

High voltage electric discharge (HVED) in disperse system "hydrocarbon liquid - powder" due to impact of plasma discharge channel, electromagnetic fields, shock waves mechanical impact, hydro flows and volume microcavitation leads to synthesis of nanocarbon, metal powders dispersion and synthesis of micro- (from 10-6 to 10-7 m) and nanosized (from 10-7 to 10-9 m) composite powders of hardening phases. Spark plasma sintering (SPS) of powder mixtures allows targeted control of grain growth rate and thus allows obtainment of multifunctional composite materials dispersion hardened by nanoparticles. Processes of HVED synthesis of micro- and nanosized powders of new compositions from elemental metal powders and their mixtures with the subsequent application of high-speed SPS of obtained powders create conditions for increase of strength (by 10-20 %), hardness and wear-resistance (by 30-60 %) of obtained materials.

Preparation of transition metal sulfide nanoparticles via hydrothermal route

International Nuclear Information System (INIS)

Fei-Ling, P.; Chin-Hua, C.; Sarani Zakaria; Tze-Khong, L.; Mohd Ambar Yarmo; Nay-Ming, H.

2010-01-01

Nano sized copper sulfide, iron sulfide and molybdenum sulfide were successfully synthesised via a simple hydrothermal method. Sodium thiosulfate pentahydrate (Na 2 S 2 O 3 ·5H 2 O) and hydroxylamine sulfate ((H 3 NO) 2 ·H 2 SO 4 ) were used as the starting materials and reacted with the transition metal source at 200 degree Celsius for 90 min. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR). Spherical shape CuS and FeS 2 nanoparticles with high crystallinity were successfully produced. The transmission electron micrographs revealed the well-dispersibility of the produced nanoparticles. Scanning electron micrograph showed the MoS 2 nanoparticles possessed a spherical shape with sheet-like structure covering on the outer surface of the particles. (author)

Effect of sonication on particle dispersion, administered dose and metal release of non-functionalized, non-inert metal nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Pradhan, Sulena; Hedberg, Jonas, E-mail: jhed@kth.se; Blomberg, Eva [KTH Royal Institute of Technology, Division of Surface and Corrosion Science, Department of Chemistry (Sweden); Wold, Susanna [KTH Royal Institute of Technology, Division of Applied Physical Chemistry, Department of Chemistry (Sweden); Odnevall Wallinder, Inger [KTH Royal Institute of Technology, Division of Surface and Corrosion Science, Department of Chemistry (Sweden)

2016-09-15

In this study, we elucidate the effect of different sonication techniques to efficiently prepare particle dispersions from selected non-functionalized NPs (Cu, Al, Mn, ZnO), and corresponding consequences on the particle dose, surface charge and release of metals. Probe sonication was shown to be the preferred method for dispersing non-inert, non-functionalized metal NPs (Cu, Mn, Al). However, rapid sedimentation during sonication resulted in differences between the real and the administered doses in the order of 30–80 % when sonicating in 1 and 2.56 g/L NP stock solutions. After sonication, extensive agglomeration of the metal NPs resulted in rapid sedimentation of all particles. DLVO calculations supported these findings, showing the strong van der Waals forces of the metal NPs to result in significant NP agglomeration. Metal release from the metal NPs was slightly increased by increased sonication. The addition of a stabilizing agent (bovine serum albumin) had an accelerating effect on the release of metals in sonicated solutions. For Cu and Mn NPs, the extent of particle dissolution increased from <1.6 to ~5 % after sonication for 15 min. A prolonged sonication time (3–15 min) had negligible effects on the zeta potential of the studied NPs. In all, it is shown that it is of utmost importance to carefully investigate how sonication influences the physico-chemical properties of dispersed metal NPs. This should be considered in nanotoxicology investigations of metal NPs.Graphical Abstract.

Conducting metal oxide and metal nitride nanoparticles

Science.gov (United States)

DiSalvo, Jr., Francis J.; Subban, Chinmayee V.

2017-12-26

Conducting metal oxide and nitride nanoparticles that can be used in fuel cell applications. The metal oxide nanoparticles are comprised of for example, titanium, niobium, tantalum, tungsten and combinations thereof. The metal nitride nanoparticles are comprised of, for example, titanium, niobium, tantalum, tungsten, zirconium, and combinations thereof. The nanoparticles can be sintered to provide conducting porous agglomerates of the nanoparticles which can be used as a catalyst support in fuel cell applications. Further, platinum nanoparticles, for example, can be deposited on the agglomerates to provide a material that can be used as both an anode and a cathode catalyst support in a fuel cell.

Taylor dispersion of nanoparticles

Science.gov (United States)

Balog, Sandor; Urban, Dominic A.; Milosevic, Ana M.; Crippa, Federica; Rothen-Rutishauser, Barbara; Petri-Fink, Alke

2017-08-01

The ability to detect and accurately characterize particles is required by many fields of nanotechnology, including materials science, nanotoxicology, and nanomedicine. Among the most relevant physicochemical properties of nanoparticles, size and the related surface-to-volume ratio are fundamental ones. Taylor dispersion combines three independent phenomena to determine particle size: optical extinction, translational diffusion, and sheer-enhanced dispersion of nanoparticles subjected to a steady laminar flow. The interplay of these defines the apparent size. Considering that particles in fact are never truly uniform nor monodisperse, we rigorously address particle polydispersity and calculate the apparent particle size measured by Taylor dispersion analysis. We conducted case studies addressing aqueous suspensions of model particles and large-scale-produced "industrial" particles of both academic and commercial interest of various core materials and sizes, ranging from 15 to 100 nm. A comparison with particle sizes determined by transmission electron microscopy confirms that our approach is model-independent, non-parametric, and of general validity that provides an accurate account of size polydispersity—independently on the shape of the size distribution and without any assumption required a priori.

Nanoparticle enhanced ionic liquid heat transfer fluids

Science.gov (United States)

Fox, Elise B.; Visser, Ann E.; Bridges, Nicholas J.; Gray, Joshua R.; Garcia-Diaz, Brenda L.

2014-08-12

A heat transfer fluid created from nanoparticles that are dispersed into an ionic liquid is provided. Small volumes of nanoparticles are created from e.g., metals or metal oxides and/or alloys of such materials are dispersed into ionic liquids to create a heat transfer fluid. The nanoparticles can be dispersed directly into the ionic liquid during nanoparticle formation or the nanoparticles can be formed and then, in a subsequent step, dispersed into the ionic liquid using e.g., agitation.

Plasma treatment of diamond nanoparticles for dispersion improvement in water

International Nuclear Information System (INIS)

Yu Qingsong; Kim, Young Jo; Ma, Hongbin

2006-01-01

Low-temperature plasmas of methane and oxygen mixtures were used to treat diamond nanoparticles to modify their surface characteristics and thus improve their dispersion capability in water. It was found that the plasma treatment significantly reduced water contact angle of diamond nanoparticles and thus rendered the nanoparticles with strong water affinity for dispersion enhancement in polar media such as water. Surface analysis using Fourier transform infrared spectroscopy confirmed that polar groups were imparted on nanoparticle surfaces. As a result, improved suspension stability was observed with plasma treated nanoparticles when dispersed in water

Transport and Dispersion of Nanoparticles in Periodic Nanopost Arrays

KAUST Repository

He, Kai; Retterer, Scott T.; Srijanto, Bernadeta R.; Conrad, Jacinta C.; Krishnamoorti, Ramanan

2014-01-01

Nanoparticles transported through highly confined porous media exhibit faster breakthrough than small molecule tracers. Despite important technological applications in advanced materials, human health, energy, and environment, the microscale mechanisms leading to early breakthrough have not been identified. Here, we measure dispersion of nanoparticles at the single-particle scale in regular arrays of nanoposts and show that for highly confined flows of dilute suspensions of nanoparticles the longitudinal and transverse velocities exhibit distinct scaling behaviors. The distributions of transverse particle velocities become narrower and more non-Gaussian when the particles are strongly confined. As a result, the transverse dispersion of highly confined nanoparticles at low Péclet numbers is significantly less important than longitudinal dispersion, leading to early breakthrough. This finding suggests a fundamental mechanism by which to control dispersion and thereby improve efficacy of nanoparticles applied for advanced polymer nanocomposites, drug delivery, hydrocarbon production, and environmental remediation. © 2014 American Chemical Society.

Transport and Dispersion of Nanoparticles in Periodic Nanopost Arrays

KAUST Repository

He, Kai

2014-05-27

Nanoparticles transported through highly confined porous media exhibit faster breakthrough than small molecule tracers. Despite important technological applications in advanced materials, human health, energy, and environment, the microscale mechanisms leading to early breakthrough have not been identified. Here, we measure dispersion of nanoparticles at the single-particle scale in regular arrays of nanoposts and show that for highly confined flows of dilute suspensions of nanoparticles the longitudinal and transverse velocities exhibit distinct scaling behaviors. The distributions of transverse particle velocities become narrower and more non-Gaussian when the particles are strongly confined. As a result, the transverse dispersion of highly confined nanoparticles at low Péclet numbers is significantly less important than longitudinal dispersion, leading to early breakthrough. This finding suggests a fundamental mechanism by which to control dispersion and thereby improve efficacy of nanoparticles applied for advanced polymer nanocomposites, drug delivery, hydrocarbon production, and environmental remediation. © 2014 American Chemical Society.

Fast adsorption kinetics of highly dispersed ultrafine nickel/carbon nanoparticles for organic dye removal

Science.gov (United States)

Kim, Taek-Seung; Song, Hee Jo; Dar, Mushtaq Ahmad; Lee, Hack-Jun; Kim, Dong-Wan

2018-05-01

Magnetic metal/carbon nano-materials are attractive for pollutant adsorption and removal. In this study, ultrafine nickel/carbon nanoparticles are successfully prepared via electrical wire explosion processing in ethanol media for the elimination of pollutant organic dyes such as Rhodamine B and methylene blue in aqueous solutions. High specific surface areas originating from both the nano-sized particles and the existence of carbon on the surface of Ni nanoparticles enhance dye adsorption capacity. In addition to this, the excellent dispersity of Ni/C nanoparticles in aqueous dye solutions leads to superior adsorption rates. The adsorption kinetics for the removal of organic dyes by Ni/C nanoparticles agree with a pseudo-second-order model and follow Freundlich adsorption isotherm behavior.

Introduction to metal-nanoparticle plasmonics

CERN Document Server

Pelton, Matthew

2013-01-01

Based on a popular article in Laser and Photonics Reviews, this book provides an explanation and overview of the techniques used to model, make, and measure metal nanoparticles, detailing results obtained and what they mean. It covers the properties of coupled metal nanoparticles, the nonlinear optical response of metal nanoparticles, and the phenomena that arise when light-emitting materials are coupled to metal nanoparticles. It also provides an overview of key potential applications and offers explanations of computational and experimental techniques giving readers a solid grounding

Cryochemistry of Metal Nanoparticles

International Nuclear Information System (INIS)

Sergeev, Gleb B.

2003-01-01

The interaction of metal atoms, clusters and nanoparticles with different organic and inorganic substances were studied at low temperature (10-40K). Combination of matrix isolation technique and preparative cryochemistry was applied for the investigation of activity and selectivity of metal particles of different size. Encapsulation of metal nanoparticles in polymers was studied. The metal-polymer films thus obtained exhibited satisfactory sensitivity to ammonia

Cryochemistry of Metal Nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Sergeev, Gleb B. [Moscow State University, Laboratory of Low Temperature Chemistry, Chemistry Department (Russian Federation)], E-mail: gbs@kinet.chem.msu.ru

2003-12-15

The interaction of metal atoms, clusters and nanoparticles with different organic and inorganic substances were studied at low temperature (10-40K). Combination of matrix isolation technique and preparative cryochemistry was applied for the investigation of activity and selectivity of metal particles of different size. Encapsulation of metal nanoparticles in polymers was studied. The metal-polymer films thus obtained exhibited satisfactory sensitivity to ammonia.

Cryochemistry of Metal Nanoparticles

Science.gov (United States)

Sergeev, Gleb B.

2003-12-01

The interaction of metal atoms, clusters and nanoparticles with different organic and inorganic substances were studied at low temperature (10-40K). Combination of matrix isolation technique and preparative cryochemistry was applied for the investigation of activity and selectivity of metal particles of different size. Encapsulation of metal nanoparticles in polymers was studied. The metal-polymer films thus obtained exhibited satisfactory sensitivity to ammonia.

Effect of silica nanoparticles on the phase inversion of liquid-liquid dispersions

International Nuclear Information System (INIS)

Asadabadi, Maliheh Raji; Abolghasemi, Hossein; Nasab, Payman Davoodi; Maragheh, Mohammad Ghannadi

2013-01-01

The effect of silica nanoparticles on phase inversion of liquid-liquid dispersions in a stirred vessel was investigated. The studied systems were toluene dispersed in water and vice versa. In the first set of experiments, phase inversion behavior of systems without Silica nanoparticles was evaluated and subsequent experiments were conducted in the presence of the nanoparticles. For this purpose, Silica nanoparticles of different concentrations (0.01, 0.03, 0.05, 0.07 wt%) were dispersed in water. The nanofluid stability was examined using an ultraviolet-visible (UV-vis) spectrophotometer. The results indicated that increase in silica nanoparticle concentrations up to 0.07 wt% led to increase in agitation speed of phase inversion 43-53.5% and 38.5-45% in the case of O/W and W/O dispersions, respectively. Consequently, the tendency of dispersions to inversion diminished as nanoparticle concentrations increased. Finally, 0.05 wt% of silica nanoparticle was selected as the optimum on the range studied

[Effect of stability and dissolution of realgar nano-particles using solid dispersion technology].

Science.gov (United States)

Guo, Teng; Shi, Feng; Yang, Gang; Feng, Nian-Ping

2013-09-01

To improve the stability and dissolution of realgar nano-particles by solid dispersion. Using polyethylene glycol 6000 and poloxamer-188 as carriers, the solid dispersions were prepare by melting method. XRD, microscopic inspection were used to determine the status of realgar nano-particles in solid dispersions. The content and stability test of As(2)0(3) were determined by DDC-Ag method. Hydride generation atomic absorption spectrometry was used to determine the content of Arsenic and investigated the in vitro dissolution behavior of solid dispersions. The results of XRD and microscopic inspection showed that realgar nano-particles in solid dispersions were amorphous. The dissolution amount and rate of Arsenic from realgar nano-particles of all solid dispersions were increased significantly, the reunion of realgar nano-particles and content of As(2)0(3) were reduced for the formation of solid dispersions. The solid dispersion of realgar nano-particles with poloxamer-188 as carriers could obviously improve stability, dissolution and solubility.

PREPARATIONS AND APPLICATION OF METAL NANOPARTICLES

Directory of Open Access Journals (Sweden)

Adlim Adlim

2010-06-01

Full Text Available Terminology of metal nanoparticles, the uniqueness properties in terms of the surface atom, the quantum dot, and the magnetism are described. The further elaboration was on the synthesis of nanoparticles. Applications of metal nanoparticles in electronic, ceramic medical and catalysis were overviewed. The bibliography includes 81 references with 99% are journal articles.   Keywords: metal nanoparticles

PREPARATIONS AND APPLICATION OF METAL NANOPARTICLES

OpenAIRE

Adlim, Adlim

2010-01-01

Terminology of metal nanoparticles, the uniqueness properties in terms of the surface atom, the quantum dot, and the magnetism are described. The further elaboration was on the synthesis of nanoparticles. Applications of metal nanoparticles in electronic, ceramic medical and catalysis were overviewed. The bibliography includes 81 references with 99% are journal articles.   Keywords: metal nanoparticles

Nanotoxicology of Metal Oxide Nanoparticles

Directory of Open Access Journals (Sweden)

Amedea B. Seabra

2015-06-01

Full Text Available This review discusses recent advances in the synthesis, characterization and toxicity of metal oxide nanoparticles obtained mainly through biogenic (green processes. The in vitro and in vivo toxicities of these oxides are discussed including a consideration of the factors important for safe use of these nanomaterials. The toxicities of different metal oxide nanoparticles are compared. The importance of biogenic synthesized metal oxide nanoparticles has been increasing in recent years; however, more studies aimed at better characterizing the potent toxicity of these nanoparticles are still necessary for nanosafely considerations and environmental perspectives. In this context, this review aims to inspire new research in the design of green approaches to obtain metal oxide nanoparticles for biomedical and technological applications and to highlight the critical need to fully investigate the nanotoxicity of these particles.

Intermetallic nanoparticles

Science.gov (United States)

Singh, Dileep; Yusufoglu, Yusuf; Timofeeva, Elena; Routbort, Jules

2015-07-14

A process for preparing intermetallic nanoparticles of two or more metals is provided. In particular, the process includes the steps: a) dispersing nanoparticles of a first metal in a solvent to prepare a first metal solution, b) forming a reaction mixture with the first metal solution and a reducing agent, c) heating the reaction mixture to a reaction temperature; and d) adding a second metal solution containing a salt of a second metal to the reaction mixture. During this process, intermetallic nanoparticles, which contain a compound with the first and second metals are formed. The intermetallic nanoparticles with uniform size and a narrow size distribution is also provided. An electrochemical device such as a battery with the intermetallic nanoparticles is also provided.

Bi-metallic nanoparticles as cathode electrocatalysts

Science.gov (United States)

Lu, Jun; Amine, Khalil; Wang, Xiaoping; Luo, Xiangyi; Myers, Deborah J.

2018-03-27

A lithium-air battery cathode catalyst includes core-shell nanoparticles on a carbon support, wherein: a core of the core-shell nanoparticles is platinum metal; and a shell of the core-shell nanoparticles is copper metal; wherein: the core-shell nanoparticles have a weight ratio of the copper metal to the platinum metal from about 4% to about 6% copper to from about 2% to about 12% platinum, with a remaining percentage being the carbon support.

Fabrication of Metallic Hollow Nanoparticles

Science.gov (United States)

Kim, Jae-Woo (Inventor); Choi, Sr., Sang H. (Inventor); Lillehei, Peter T. (Inventor); Chu, Sang-Hyon (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

2016-01-01

Metal and semiconductor nanoshells, particularly transition metal nanoshells, are fabricated using dendrimer molecules. Metallic colloids, metallic ions or semiconductors are attached to amine groups on the dendrimer surface in stabilized solution for the surface seeding method and the surface seedless method, respectively. Subsequently, the process is repeated with additional metallic ions or semiconductor, a stabilizer, and NaBH.sub.4 to increase the wall thickness of the metallic or semiconductor lining on the dendrimer surface. Metallic or semiconductor ions are automatically reduced on the metallic or semiconductor nanoparticles causing the formation of hollow metallic or semiconductor nanoparticles. The void size of the formed hollow nanoparticles depends on the dendrimer generation. The thickness of the metallic or semiconductor thin film around the dendrimer depends on the repetition times and the size of initial metallic or semiconductor seeds.

New organometallic salts as precursors for the functionalization of carbon nanotubes with metallic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Alonso-Nunez, G., E-mail: galonso@cnyn.unam.mx; Garza, L. Morales de la; Rogel-Hernandez, E.; Reynoso, E. [Universidad Nacional Autonoma de Mexico, Centro de Nanociencias y Nanotecnologia (Mexico); Licea-Claverie, A.; Felix-Navarro, R. M. [Instituto Tecnologico de Tijuana, Centro de Graduados e Investigacion (Mexico); Berhault, G. [UMR 5256 CNRS-Universite de Lyon, Institut de Recherches sur la Catalyse et l' Environnement de Lyon (France); Paraguay-Delgado, F. [Centro de Investigacion en Materiales Avanzados S. C. (Mexico)

2011-09-15

New organometallic salts were synthesized in aqueous solution and were used as precursors for the functionalization of carbon nanotubes (CNT) by metallic nanoparticles. The precursors were obtained by reaction between HAuCl{sub 4}, (NH{sub 4}){sub 2}PtCl{sub 6}, (NH{sub 4}){sub 2}PdCl{sub 6}, or (NH{sub 4}){sub 3}RhCl{sub 6} with cetyltrimethylammonium bromide (CTAB). The as-obtained (CTA){sub n}Me{sub x}Cl{sub y} salts (with Me = Au, Pt, Pd, Rh) were characterized by Fourier-transform infra-red (FTIR) spectroscopy, {sup 1}H nuclear magnetic resonance (NMR) spectroscopy, and thermogravimetric analysis. These precursors were then used to synthesize metallic nanoparticles of Au, Pt, Pd, and Rh over multiwalled carbon nanotubes (MWCNT). Characterization by scanning transmission electron microscopy (STEM) and thermogravimetric analysis under air reveals that the CNT-supported catalysts exhibit high loading and good dispersion of the metallic nanoparticles with small average particle sizes. The present preparation procedure therefore allows obtaining high densities of small metallic nanoparticles at the surface of MWCNT.

Synthesis, structural and optical properties of PVP coated transition metal doped ZnS nanoparticles

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Desai, N. V.; Shaikh, I. A.; Rawal, K. G.; Shah, D. V.

2018-05-01

The room temperature photoluminescence (PL) of transition metal doped ZnS nanoparticles is investigated in the present study. The PVP coated ZnS nanoparticles doped with transition metals are synthesized by facile wet chemical co-precipitation method with the concentration of impurity 1%. The UV-Vis absorbance spectra have a peak at 324nm which shifts slightly to 321nm upon introduction of the impurity. The incorporation of the transition metal as dopant is confirmed by X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The particle size and the morphology are characterized by scanning electron microscopy (SEM), XRD and UV-Vis spectroscopy. The average size of synthesized nanoparticles is about 2.6nm. The room temperature photoluminescence (PL) of undoped and doped ZnS nanoparticles show a strong and sharp peak at 782nm and 781.6nm respectively. The intensity of the PL changes with the type of doping having maximum for manganese (Mn).

Evaluation of twin-head electrospray nanoparticle disperser for nanotoxicity study

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Liu, Qiaoling; Budiman, Thomas; Chen, Da-Ren

2014-08-01

With the rapid development of nanotechnology, nanoparticles with various sizes and compositions have been synthesized and proposed for industrial applications. At the same time, the health effects and environmental impacts of nanoparticles become an emerging concern to be addressed. Both in vitro and in vivo studies are of importance to better understand the toxicity of nanoparticles. It is thus essential to have a nanoparticle disperser capable of dispersing individual nanoparticles for these studies. A twin-head electrospray (THES) nanoparticle disperser for animal inhalation exposure studies has recently become commercially available from TSE Systems Inc. Different from the cone-jet electrospray method used in the majority of literature, this particular disperser operates at the multi-jet mode. In this study, we reported our finding on the performance evaluation of the THES disperser with respect to its mass throughput and quality of size distribution of aerosol produced. Three different nanomaterials (TiO2, ZnO, and NiO) were used in this study. It is found that the maximal mass throughput of the studied disperser was achieved by keeping the distance between two opposite spray capillary tips at 3.0 cm, operating the primary carrier-to-capillary sheath flow rates at the ratio of 4:3, and feeding spray suspensions at a flow rate of 20 µl/min. Under the above settings and operations, the highest mass concentration for nano-ZnO was measured at 14.56 mg/m3. Nanoparticle streams with higher concentrations can be further produced by lowering the total carrier gas flow rate and spraying suspensions of higher nanomaterial concentrations. Our study also found that the particle mass throughput of the studied disperser had a good linear relationship with the mass concentration of spray suspension. In addition, the spatial uniformity of nano aerosol distribution in a TSE head-nose-only exposure chamber was investigated. An acceptable nano aerosol uniformity result was

Tunable Optical Properties of Metal Nanoparticle Sol-Gel Composites

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Smith, David D.; Snow, Lanee A.; Sibille, Laurent; Ignont, Erica

2001-01-01

We demonstrate that the linear and non-linear optical properties of sol-gels containing metal nanoparticles are highly tunable with porosity. Moreover, we extend the technique of immersion spectroscopy to inhomogeneous hosts, such as aerogels, and determine rigorous bounds for the average fractional composition of each component, i.e., the porosity of the aerogel, or equivalently, for these materials, the catalytic dispersion. Sol-gels containing noble metal nanoparticles were fabricated and a significant blue-shift in the surface plasmon resonance (SPR) was observed upon formation of an aerogel, as a result of the decrease in the dielectric constant of the matrix upon supercritical extraction of the solvent. However, as a result of chemical interface damping and aggregation this blue-shift does not strictly obey standard effective medium theories. Mitigation of these complications is achieved by avoiding the use of alcohol and by annealing the samples in a reducing atmosphere.

Nanotoxicity: the toxicity research progress of metal and metal-containing nanoparticles.

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Ding, Lingling; Liu, Zhidong; Aggrey, Mike Okweesi; Li, Chunhua; Chen, Jing; Tong, Ling

2015-01-01

Along with the exuberant development of nanotechnology, a large number of nanoformulations or non materials are successfully applied in the clinics, biomedicine, cosmetics and industry. Despite some unique advantages of nanoformulations, there exist potentially worrying toxic effects, particularly those related to metal and metal-containing nanoparticles (NPs). Although various researches have been conducted to assess the metallic and metal-containing nanoparticles toxic effects, only little is known about the toxicity expressive types and evaluation, reasons and mechanisms, influencing factors and research methods of metal and metal-containing nanotoxicity. Therefore, it is of importance to acquire a better understanding of metal and metal-containing nanoparticles toxicity for medical application. This review presents a summary on the metal and metal-containing nanoparticles toxicity research progress consulting relevant literature.

Dispersions of silica nanoparticles in ionic liquids investigated with advanced rheology

International Nuclear Information System (INIS)

Wittmar, Alexandra; Ruiz-Abad, David; Ulbricht, Mathias

2012-01-01

The colloidal stabilities of dispersions of unmodified and surface-functionalized SiO 2 nanoparticles in hydrophobic and hydrophilic imidazolium-based ionic liquids were studied with advanced rheology at three temperatures (25, 100, and 200 °C). The rheological behavior of the dispersions was strongly affected by the ionic liquids hydrophilicity, by the nanoparticles surface, by the concentration of the nanoparticles in the dispersion as well as by the temperature. The unmodified hydrophilic nanoparticles showed a better compatibility with the hydrophilic ionic liquid. The SiO 2 surface functionalization with hydrophobic groups clearly improved the colloidal stability of the dispersions in the hydrophobic ionic liquid. The temperature increase was found to lead to a destabilization in all studied systems, especially at higher concentrations. The results of this study imply that ionic liquids with tailored properties could be used in absorbers directly after reactors for gas-phase synthesis of nanoparticles or/and as solvents for their further surface functionalization without agglomeration or aggregation.

Chemoelectronic circuits based on metal nanoparticles

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Yan, Yong; Warren, Scott C.; Fuller, Patrick; Grzybowski, Bartosz A.

2016-07-01

To develop electronic devices with novel functionalities and applications, various non-silicon-based materials are currently being explored. Nanoparticles have unique characteristics due to their small size, which can impart functions that are distinct from those of their bulk counterparts. The use of semiconductor nanoparticles has already led to improvements in the efficiency of solar cells, the processability of transistors and the sensitivity of photodetectors, and the optical and catalytic properties of metal nanoparticles have led to similar advances in plasmonics and energy conversion. However, metals screen electric fields and this has, so far, prevented their use in the design of all-metal nanoparticle circuitry. Here, we show that simple electronic circuits can be made exclusively from metal nanoparticles functionalized with charged organic ligands. In these materials, electronic currents are controlled by the ionic gradients of mobile counterions surrounding the ‘jammed’ nanoparticles. The nanoparticle-based electronic elements of the circuitry can be interfaced with metal nanoparticles capable of sensing various environmental changes (humidity, gas, the presence of various cations), creating electronic devices in which metal nanoparticles sense, process and ultimately report chemical signals. Because the constituent nanoparticles combine electronic and chemical sensing functions, we term these systems ‘chemoelectronic’. The circuits have switching times comparable to those of polymer electronics, selectively transduce parts-per-trillion chemical changes into electrical signals, perform logic operations, consume little power (on the scale of microwatts), and are mechanically flexible. They are also ‘green’, in the sense that they comprise non-toxic nanoparticles cast at room temperature from alcohol solutions.

Method for producing metallic nanoparticles

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Phillips, Jonathan; Perry, William L.; Kroenke, William J.

2004-02-10

Method for producing metallic nanoparticles. The method includes generating an aerosol of solid metallic microparticles, generating non-oxidizing plasma with a plasma hot zone at a temperature sufficiently high to vaporize the microparticles into metal vapor, and directing the aerosol into the hot zone of the plasma. The microparticles vaporize in the hot zone to metal vapor. The metal vapor is directed away from the hot zone and to the plasma afterglow where it cools and condenses to form solid metallic nanoparticles.

Microwave irradiation for the facile synthesis of transition-metal nanoparticles (NPs) in ionic liquids (ILs) from metal-carbonyl precursors and Ru-, Rh-, and Ir-NP/IL dispersions as biphasic liquid-liquid hydrogenation nanocatalysts for cyclohexene.

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Vollmer, Christian; Redel, Engelbert; Abu-Shandi, Khalid; Thomann, Ralf; Manyar, Haresh; Hardacre, Christopher; Janiak, Christoph

2010-03-22

Stable chromium, molybdenum, tungsten, manganese, rhenium, ruthenium, osmium, cobalt, rhodium, and iridium metal nanoparticles (M-NPs) have been reproducibly obtained by facile, rapid (3 min), and energy-saving 10 W microwave irradiation (MWI) under an argon atmosphere from their metal-carbonyl precursors [M(x)(CO)(y)] in the ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF(4)]). This MWI synthesis is compared to UV-photolytic (1000 W, 15 min) or conventional thermal decomposition (180-250 degrees C, 6-12 h) of [M(x)(CO)(y)] in ILs. The MWI-obtained nanoparticles have a very small (TED), and dynamic light scattering (DLS)). The ruthenium, rhodium, or iridium nanoparticle/IL dispersions are highly active and easily recyclable catalysts for the biphasic liquid-liquid hydrogenation of cyclohexene to cyclohexane with activities of up to 522 (mol product) (mol Ru)(-1) h(-1) and 884 (mol product) (mol Rh)(-1) h(-1) and give almost quantitative conversion within 2 h at 10 bar H(2) and 90 degrees C. Catalyst poisoning experiments with CS(2) (0.05 equiv per Ru) suggest a heterogeneous surface catalysis of Ru-NPs.

Potassium iodate assisted synthesis of titanium dioxide nanoparticles with superior water-dispersibility.

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Wang, Yawen; Duo, Fangfang; Peng, Shiqi; Jia, Falong; Fan, Caimei

2014-09-15

In this paper, we report a novel polyol process to synthesize highly water-dispersible anatase titanium dioxide (TiO2) nanoparticles (∼5 nm) by the introduction of inorganic oxidizing agent--KIO3. The obtained TiO2 nanoparticles are well dispersible in water at pH≥5.0 and the resulting aqueous dispersion remains stable over months. The superior water-dispersibility of as-formed TiO2 is ascribed to the electrostatic repulsion from carboxylic acid group modified on TiO2 nanoparticles, which is the oxidation product of solvent diethylene glycol (DEG) by KIO3. Based on the characterization results, the formation processes of water-dispersibility TiO2 nanoparticles are proposed. Meanwhile, the synthesized TiO2 nanoparticles are found to be doped by iodine and exhibit excellent photocatalytic activity on degradation of rhodamine-B (RhB) under visible-light irradiation. The further tests demonstrate that the O(2-) is the main active species during photodegradation of RhB. Copyright © 2014 Elsevier Inc. All rights reserved.

Nanotoxicity: oxidative stress mediated toxicity of metal and metal oxide nanoparticles.

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Sarkar, Abhijit; Ghosh, Manoranjan; Sil, Parames Chandra

2014-01-01

Metal and metal oxide nanoparticles are often used as industrial catalysts or to improve product's functional properties. Recent advanced nanotechnology have been expected to be used in various fields, ranging from sensors, environmental remediation to biomedicine, medical biology and imaging, etc. However, the growing use of nanoparticles has led to their release into environment and increased levels of these particles at nearby sites or the surroundings of their manufacturing factories become obvious. The toxicity of metal and metal oxide nanoparticles on humans, animals, and certainly to the environment has become a major concern to our community. However, controversies still remain with respect to the toxic effects and the mechanisms of these nanoparticles. The scientific community now feels that an understanding of the toxic effects is necessary to handle these nanoparticles and their use. A new discipline, named nanotoxicology, has therefore been developed that basically refers to the study of the interactions of nanoparticles with biological systems and also measures the toxicity level related to human health. Nanoparticles usually generate reactive oxygen species to a greater extent than micro-sized particles resulting in increased pro-inflammatory reactions and oxidative stress via intracellular signaling pathways. In this review, we mainly focus on the routes of exposure of some metal and metal oxide nanoparticles and how these nanoparticles affect us or broadly the cells of our organs. We would also like to discuss the responsible mechanism(s) of the nanoparticle-induced reactive oxygen species mediated organ pathophysiology. A brief introduction of the characterization and application of these nanoparticles has also been included in the article.

Antimicrobial Polymers with Metal Nanoparticles

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Palza, Humberto

2015-01-01

Metals, such as copper and silver, can be extremely toxic to bacteria at exceptionally low concentrations. Because of this biocidal activity, metals have been widely used as antimicrobial agents in a multitude of applications related with agriculture, healthcare, and the industry in general. Unlike other antimicrobial agents, metals are stable under conditions currently found in the industry allowing their use as additives. Today these metal based additives are found as: particles, ions absorbed/exchanged in different carriers, salts, hybrid structures, etc. One recent route to further extend the antimicrobial applications of these metals is by their incorporation as nanoparticles into polymer matrices. These polymer/metal nanocomposites can be prepared by several routes such as in situ synthesis of the nanoparticle within a hydrogel or direct addition of the metal nanofiller into a thermoplastic matrix. The objective of the present review is to show examples of polymer/metal composites designed to have antimicrobial activities, with a special focus on copper and silver metal nanoparticles and their mechanisms. PMID:25607734

Speciation dynamics of metals in dispersion of nanoparticles with discrete distribution of charged binding sites.

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Polyakov, Pavel D; Duval, Jérôme F L

2014-02-07

We report a comprehensive theory to evaluate the kinetics of complex formation between metal ions and charged spherical nanoparticles. The latter consist of an ion-impermeable core surrounded by a soft shell layer characterized by a discrete axisymmetric 2D distribution of charged sites that bind metal ions. The theory explicitly integrates the conductive diffusion of metal ions from bulk solution toward the respective locations of the reactive sites within the particle shell volume. The kinetic constant k for outer-sphere nanoparticle-metal association is obtained from the sum of the contributions stemming from all reactive sites, each evaluated from the corresponding incoming flux of metal ions derived from steady-state Poisson-Nernst-Planck equations. Illustrations are provided to capture the basic intertwined impacts of particle size, overall particle charge, spatial heterogeneity in site distribution, type of particle (hard, core-shell or porous) and concentration of the background electrolyte on k. As a limit, k converges with predictions from previously reported analytical expressions derived for porous particles with low and high charge density, cases that correspond to coulombic and mean-field (smeared-out) electrostatic treatments, respectively. The conditions underlying the applicability of these latter approaches are rigorously identified in terms of (i) the extent of overlap between electric double layers around charged neighbouring sites, and (ii) the magnitude of the intraparticulate metal concentration gradient. For the first time, the proposed theory integrates the differentiated impact of the local potential around the charged binding sites amidst the overall particle field, together with that of the so-far discarded intraparticulate flux of metal ions.

Slow and stopped light in active gain composite materials of metal nanoparticles. Ultralarge group index-bandwidth product predicted

Energy Technology Data Exchange (ETDEWEB)

Kim, Kwang-Hyon; Choe, Song-Hyok [Institute of Lasers, State Academy of Sciences, Unjong District, Pyongyang (Korea, Democratic People' s Republic of)

2017-08-15

Chip-compatible slow light devices with large group index-bandwidth products and low losses are of great interest in the community of modern photonics. In this work, active gain materials containing metal nanoparticles are proposed as the slow and stopped light materials. Gain-assisted high field enhancement in metal nanoparticles and the resultant strong dispersion lead to such phenomena. From the Maxwell-Garnett model, it is revealed that the metal nanocomposite exhibits the infinitely large group index when the gain of the host medium and the filling factor of metal nanoparticles satisfy a critical condition. For the gain of the host above the critical value, one can observe slowing down effect with amplification of light pulses. Significantly large group index-bandwidth products, which vary from a few to several thousand or even infinity depending on the gain value of the host medium, have been numerically predicted in active silica glasses containing spheroidal metal nanoparticles, as examples. The proposed scheme inherently provides the widely varying operating spectral range by changing the aspect ratio of metal nanoparticles and chip-compatibility with low cost. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Low molecular weight compounds as effective dispersing agents in the formation of colloidal silver nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Natsuki, Jun; Natsuki, Toshiaki, E-mail: natsuki@shinshu-u.ac.jp; Abe, Takao [Shinshu University, Faculty of Textile Science and Technology (Japan)

2013-03-15

A convenient method to synthesize uniform, well-dispersed colloidal silver nanoparticles is described. Aldonic acid or {alpha}-hydroxy acid compounds of low molecular weight are used instead of polymeric compounds as dispersing agents to prepare silver nanoparticles. The size, conformation, and electrical conductivity of the silver nanoparticles, and the effect and function of the dispersing agents are investigated in detail. Using these low molecular weight compounds as dispersing agents, silver nanoparticles with a diameter of 10 nm or less and high electrical conductivity can be obtained. In addition, this procedure allows silver nanoparticles to be sintered at 150 Degree-Sign C, which is lower than that required for silver nanoparticle formulation using polymeric compounds (200 Degree-Sign C). The silver nanoparticles produced by this process can be used to prepare various inks and to manufacture electronic circuits. It is found that low molecular weight compounds are more effective dispersing agents than polymeric compounds in the formation of silver nanoparticles.

Cytotoxicity and oxidative stress induced by different metallic nanoparticles on human kidney cells

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Ohayon-Courtès Céline

2011-03-01

Full Text Available Abstract Background Some manufactured nanoparticles are metal-based and have a wide variety of applications in electronic, engineering and medicine. Until now, many studies have described the potential toxicity of NPs on pulmonary target, while little attention has been paid to kidney which is considered to be a secondary target organ. The objective of this study, on human renal culture cells, was to assess the toxicity profile of metallic nanoparticles (TiO2, ZnO and CdS usable in industrial production. Comparative studies were conducted, to identify whether particle properties impact cytotoxicity by altering the intracellular oxidative status. Results Nanoparticles were first characterized by size, surface charge, dispersion and solubility. Cytotoxicity of NPs was then evaluated in IP15 (glomerular mesangial and HK-2 (epithelial proximal cell lines. ZnO and CdS NPs significantly increased the cell mortality, in a dose-dependent manner. Cytotoxic effects were correlated with the physicochemical properties of NPs tested and the cell type used. Analysis of reactive oxygen species and intracellular levels of reduced and oxidized glutathione revealed that particles induced stress according to their composition, size and solubility. Protein involved in oxidative stress such as NF-κb was activated with ZnO and CdS nanoparticles. Such effects were not observed with TiO2 nanoparticles. Conclusion On glomerular and tubular human renal cells, ZnO and CdS nanoparticles exerted cytotoxic effects that were correlated with metal composition, particle scale and metal solubility. ROS production and oxidative stress induction clearly indicated their nephrotoxic potential.

Shuttling single metal atom into and out of a metal nanoparticle.

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Wang, Shuxin; Abroshan, Hadi; Liu, Chong; Luo, Tian-Yi; Zhu, Manzhou; Kim, Hyung J; Rosi, Nathaniel L; Jin, Rongchao

2017-10-10

It has long been a challenge to dope metal nanoparticles with a specific number of heterometal atoms at specific positions. This becomes even more challenging if the heterometal belongs to the same group as the host metal because of the high tendency of forming a distribution of alloy nanoparticles with different numbers of dopants due to the similarities of metals in outmost electron configuration. Herein we report a new strategy for shuttling a single Ag or Cu atom into a centrally hollow, rod-shaped Au 24 nanoparticle, forming AgAu 24 and CuAu 24 nanoparticles in a highly controllable manner. Through a combined approach of experiment and theory, we explain the shuttling pathways of single dopants into and out of the nanoparticles. This study shows that the single dopant is shuttled into the hollow Au 24 nanoparticle either through the apex or side entry, while shuttling a metal atom out of the Au 25 to form the Au 24 nanoparticle occurs mainly through the side entry.Doping a metal nanocluster with heteroatoms dramatically changes its properties, but it remains difficult to dope with single-atom control. Here, the authors devise a strategy to dope single atoms of Ag or Cu into hollow Au nanoclusters, creating precise alloy nanoparticles atom-by-atom.

Natural reducing agents for electroless nanoparticle deposition: Mild synthesis of metal/carbon nanostructured microspheres

International Nuclear Information System (INIS)

Duffy, Paul; Reynolds, Lyndsey A.; Sanders, Stephanie E.; Metz, Kevin M.; Colavita, Paula E.

2013-01-01

Composite materials are of interest because they can potentially combine the properties of their respective components in a manner that is useful for specific applications. Here, we report on the use of coffee as a low-cost, green reductant for the room temperature formation of catalytically active, supported metal nanoparticles. Specifically, we have leveraged the reduction potential of coffee in order to grow Pd and Ag nanoparticles at the surface of porous carbon microspheres synthesized via ultraspray pyrolysis. The metal nanoparticle-on-carbon microsphere composites were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). To demonstrate the catalytic activity of Pd/C and Ag/C materials, Suzuki coupling reactions and nitroaromatic reduction reactions were employed, respectively. - Highlights: • Natural reductants were used as green electroless deposition reagents. • Room temperature synthesis of supported Ag and Pd nanoparticles was achieved. • Carbon porous microspheres were used as supports. • Synthesis via natural reductants yielded catalytically active nanoparticles.

Plasmon polaritons in cubic lattices of spherical metallic nanoparticles

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Lamowski, Simon; Mann, Charlie-Ray; Hellbach, Felicitas; Mariani, Eros; Weick, Guillaume; Pauly, Fabian

2018-03-01

We theoretically investigate plasmon polaritons in cubic lattices of spherical metallic nanoparticles. The nanoparticles, each supporting triply-degenerate localized surface plasmons, couple through the Coulomb dipole-dipole interaction, giving rise to collective plasmons that extend over the whole metamaterial. The latter hybridize with photons forming plasmon polaritons, which are the hybrid light-matter eigenmodes of the system. We derive general analytical expressions to evaluate both plasmon and plasmon-polariton dispersions and the corresponding eigenstates. These are obtained within a Hamiltonian formalism, which takes into account retardation effects in the dipolar interaction between the nanoparticles and considers the dielectric properties of the nanoparticles as well as their surrounding. Within this model we predict polaritonic splittings in the near-infrared to the visible range of the electromagnetic spectrum that depend on polarization, lattice symmetry, and wave-vector direction. Finally, we show that the predictions of our model are in excellent quantitative agreement with conventional finite-difference frequency-domain simulations, but with the advantages of analytical insight and significantly reduced computational cost.

Effect of sacrificial agents on the dispersion of metal cocatalysts for photocatalytic hydrogen evolution

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Cao, Shaowen; Shen, Baojia; Huang, Qian; Chen, Zhe

2018-06-01

Surface photodeposition of noble metal cocatalyst has been regarded as an effective approach to facilitate the separation of charge carriers and reduce the over-potential of water reduction, thus to enhance the photocatalytic H2-production activities of semiconductor photocatalyst. Herein, the influences of sacrificial agents used in the photodeposition process on the dispersion of noble metal nanoparticles are investigated, via a series of technique of photocatalytic hydrogen evolution test, microstructure analysis and photoelectrochemical measurement. As a result, the sacrificial agents are found to show large impact on the loading amount, particle size and distribution of different metals on the surface of g-C3N4. The real loading amount of Pt and Au is higher in methanol solution than that in triethanolamine solution. Better distribution and smaller size of Pt nanoparticles are achieved in the presence of methanol; while better distribution and smaller size of Au nanoparticles are achieved in the presence of triethanolamine. As a result, quite different charge transfer ability is achieved for the synthesized Pt and Au decorated g-C3N4, which subsequently leads to disparate photocatalytic activities of the same g-C3N4 photocatalyst under various conditions. The finding in this work indicates that the valid deposition content, particle size and distribution of metal cocatalysts should be carefully taken into account when comparing the photocatalytic activities among various samples.

Synthesis of Metal Nanoparticles by Bacteria

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Fikriye Alev Akçay

2018-04-01

Full Text Available Metal particles reduced to nano size by nanotechnological methods are confronted in many different fields such as biomedical and physicochemical, pharmaceutical, electric-electronic, automotive and food industries. Nanoparticles can be produced using chemical, physical and biological methods, of which chemical processes are in common use. However, physical and chemical methods are not environmentally friendly and economical because they require the use of high temperature, high pressure and toxic chemicals. For this reason, interest in the production of metal nanoparticles by biological methods, also called green technology, an environmentally friendly and sustainable approach, has increased in recent years. With some plant extracts and intracellular and extracellular secretions of microorganisms, some reduction reactions take place and metal nanoparticles are produced. Bacteria have been actively involved in nanotechnology in recent years due to their diversity in nature, their ease of isolation, and ease of nanoparticle synthesis. In this article, production and application of metal nanoparticles by using bacterial methods have been reviewed.

Recent Advances in Antimicrobial Hydrogels Containing Metal Ions and Metals/Metal Oxide Nanoparticles

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Fazli Wahid

2017-11-01

Full Text Available Recently, the rapid emergence of antibiotic-resistant pathogens has caused a serious health problem. Scientists respond to the threat by developing new antimicrobial materials to prevent or control infections caused by these pathogens. Polymer-based nanocomposite hydrogels are versatile materials as an alternative to conventional antimicrobial agents. Cross-linking of polymeric materials by metal ions or the combination of polymeric hydrogels with nanoparticles (metals and metal oxide is a simple and effective approach for obtaining a multicomponent system with diverse functionalities. Several metals and metal oxides such as silver (Ag, gold (Au, zinc oxide (ZnO, copper oxide (CuO, titanium dioxide (TiO2 and magnesium oxide (MgO have been loaded into hydrogels for antimicrobial applications. The incorporation of metals and metal oxide nanoparticles into hydrogels not only enhances the antimicrobial activity of hydrogels, but also improve their mechanical characteristics. Herein, we summarize recent advances in hydrogels containing metal ions, metals and metal oxide nanoparticles with potential antimicrobial properties.

Influential factors of 2-chlorobiphenyl reductive dechlorination by highly dispersed bimetallic nanoparticles

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Jiang Junrong

2016-01-01

Full Text Available Highly dispersed Pd-Fe0 bimetallic nanoparticles were prepared in the presence of 40 kHz ultrasonic irradiation in order to enhance disparity and reactivity, and simultaneously avoid agglomeration. Influential factors of 2-chlorobiphenyl (2-Cl BP reductive dechlorination by highly dispersed Pd-Fe0 nanoparticles were investigated. Experimental results showed that highly dispersed Pd-Fe0 nanoparticles prepared in the in the presence of ultrasound could further improve the dechlorination efficiency of 2-Cl BP, meanwhile the biphenyl (BP formation rates increased obviously and increased from 47.4% (in the absence of ultrasound to 95.3% (in the presence of ultrasound within 300 min. The catalytic reductive dechlorination effciency of 2-Cl BP was dependent on Pd-Fe0 nanoparticles prepared methods, Pd-Fe0 nanoparticles dosage, Pd loading percentage over Fe0 and initial pH values

Sustainable green catalysis by supported metal nanoparticles.

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Fukuoka, Atsushi; Dhepe, Paresh L

2009-01-01

The recent progress of sustainable green catalysis by supported metal nanoparticles is described. The template synthesis of metal nanoparticles in ordered porous materials is studied for the rational design of heterogeneous catalysts capable of high activity and selectivity. The application of these materials in green catalytic processes results in a unique activity and selectivity arising from the concerted effect of metal nanoparticles and supports. The high catalytic performances of Pt nanoparticles in mesoporous silica is reported. Supported metal catalysts have also been applied to biomass conversion by heterogeneous catalysis. Additionally, the degradation of cellulose by supported metal catalysts, in which bifunctional catalysis of acid and metal plays the key role for the hydrolysis and reduction of cellulose, is also reported. Copyright 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.

Tunable solvation effects on the size-selective fractionation of metal nanoparticles in CO2 gas-expanded solvents.

Science.gov (United States)

Anand, Madhu; McLeod, M Chandler; Bell, Philip W; Roberts, Christopher B

2005-12-08

This paper presents an environmentally friendly, inexpensive, rapid, and efficient process for size-selective fractionation of polydisperse metal nanoparticle dispersions into multiple narrow size populations. The dispersibility of ligand-stabilized silver and gold nanoparticles is controlled by altering the ligand tails-solvent interaction (solvation) by the addition of carbon dioxide (CO2) gas as an antisolvent, thereby tailoring the bulk solvent strength. This is accomplished by adjusting the CO2 pressure over the liquid, resulting in a simple means to tune the nanoparticle precipitation by size. This study also details the influence of various factors on the size-separation process, such as the types of metal, ligand, and solvent, as well as the use of recursive fractionation and the time allowed for settling during each fractionation step. The pressure range required for the precipitation process is the same for both the silver and gold particles capped with dodecanethiol ligands. A change in ligand or solvent length has an effect on the interaction between the solvent and the ligand tails and therefore the pressure range required for precipitation. Stronger interactions between solvent and ligand tails require greater CO2 pressure to precipitate the particles. Temperature is another variable that impacts the dispersibility of the nanoparticles through changes in the density and the mole fraction of CO2 in the gas-expanded liquids. Recursive fractionation for a given system within a particular pressure range (solvent strength) further reduces the polydispersity of the fraction obtained within that pressure range. Specifically, this work utilizes the highly tunable solvent properties of organic/CO2 solvent mixtures to selectively size-separate dispersions of polydisperse nanoparticles (2 to 12 nm) into more monodisperse fractions (+/-2 nm). In addition to providing efficient separation of the particles, this process also allows all of the solvent and

Synthesis and characterization of ultrafine well-dispersed magnetic nanoparticles

International Nuclear Information System (INIS)

Liu, Z.L.; Wang, H.B.; Lu, Q.H.; Du, G.H.; Peng, L.; Du, Y.Q.; Zhang, S.M.; Yao, K.L.

2004-01-01

Ultrafine well-dispersed magnetic nanoparticles were directly prepared in aqueous solution using controlled coprecipitation method. The structure, size, size distributions and magnetic properties of the magnetic nanoparticles, characterized by TEM, XRD and VSM, indicated the formation of single domain nanoparticles with average size smaller than 5 nm. The magnetic nanoparticles show superparamagnetism and a lower saturation magnetization is found as a consequence of smaller particle size. The relevant conditions for obtaining these magnetic colloids are discussed and the so-prepared magnetic nanoparticles are stable in a wide pH range

Influence of metal nanoparticle decorated CNTs on polyurethane based electro active shape memory nanocomposite actuators

International Nuclear Information System (INIS)

Raja, Mohan; Shanmugharaj, A.M.; Ryu, Sung Hun; Subha, J.

2011-01-01

Highlights: → Polyurethane based on pristine and metal (Ag and Cu) nanoparticle decorated CNTs nanocomposites are prepared through melt blending process. → The electrical, mechanical, dynamic mechanical, thermal conductivity and electro active shape memory properties of the PU nanocomposites were investigated. → The influence of metal nanoparticle decorated CNTs showed significant improvement in their all properties to compare to pristine CNTs. → Electro active shape memory studies of the PU/M-CNTs nanocomposites reveal extraordinary recoverability of its shape at lower applied dc voltages. - Abstract: Polymer nanocomposites based on thermoplastic polyurethane (PU) elastomer and metal nanoparticle (Ag and Cu) decorated multiwall carbon nanotubes (M-CNTs) were prepared through melt mixing process and investigated for its mechanical, dynamic mechanical and electro active shape memory properties. Structural characterization and morphological characterization of the PU nanocomposites were done using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Morphological characterization revealed better dispersion of M-CNTs in the polyurethane, which is attributed to the improved interaction between the M-CNTs and polyurethane. Loading of the metal nanoparticle coated carbon nanotubes resulted in the significant improvement on the mechanical properties such as tensile strength of the PU composites in comparison to the pristine carbon nanotubes (P-CNTs). Dynamic mechanical analysis showed that the glass transition temperature (Tg) of the polyurethane increases slightly with increasing loading of both pristine and metal nanoparticle functionalized carbon nanotubes. The metal nanoparticles decorated carbon nanotubes also showed significant improvement in the thermal and electrical conductivity of the PU/M-CNTs nanocomposites. Shape memory studies of the PU/M-CNTs nanocomposites exhibit remarkable recoverability of its shape at lower applied dc voltages.

Bioinspired metal-cell wall-metal sandwich structure on an individual bacterial cell scaffold.

Science.gov (United States)

Zhang, Xiaoliang; Yu, Mei; Liu, Jianhua; Li, Songmei

2012-08-25

Pd nanoparticles were introduced to individual Bacillus cells and dispersedly anchored on both the inside and outside of the cell walls. The anchored nanoparticles served as "seeds" to drive the formation of double metallic layers forming a metal-cell wall-metal sandwich structure at the single-cell level.

Re-dispersible Li+ and Eu3+ co-doped CdS nanoparticles ...

Indian Academy of Sciences (India)

Also, it can be used as sensor for drug delivery in our body [12,13]. In the present work, we prepare re-dispersible CdS, Li+- and Eu3+-doped CdS nanoparticles in organic solvent by urea hydrolysis at 170◦C and their lumines- cence properties are studied. We propose the mechanism of re-dispersion of CdS nanoparticles ...

Dispersion stability of nanoparticles in ecotoxicological investigations: the need for adequate measurement tools

Energy Technology Data Exchange (ETDEWEB)

Tantra, Ratna, E-mail: ratna.tantra@npl.co.uk; Jing Shingheng; Pichaimuthu, Sivaraman K. [National Physical Laboratory (United Kingdom); Walker, Nicholas [University of Exeter, School of Biosciences (United Kingdom); Noble, James [National Physical Laboratory (United Kingdom); Hackley, Vincent A. [National Institute of Standards and Technology (United States)

2011-09-15

One of the main challenges in nanoecotoxicological investigations is in the selection of the most suitable measurement methods and protocols for nanoparticle characterisation. Several parameters have been identified as being important as they govern nanotoxicological activity, with some parameters being better defined than others. For example, as a parameter, there is some ambiguity as to how to measure dispersion stability in the context of ecotoxicological investigations; indeed, there is disagreement over which are the best methods to measure nanoparticle dispersion stability. The purpose of this article is to use various commercially available tools to measure dispersion stability and to understand the information given by each tool. In this study, CeO{sub 2} was dispersed in two different types of media: de-ionised water and electrolyte-containing fish medium. The DLS mean particle size of freshly dispersed sample in DI water was {approx}200 nm in diameter. A visual sedimentation experiment showed that nanoparticle dispersion made in the fish medium was less stable compared to corresponding dispersion in de-ionised water. Stability of these dispersions was monitored using various techniques, for a period of 3 days. Our findings have shown that dispersion stability can be suitably assessed by monitoring: (a) surface charge, (b) sedimentation events and (c) presence of agglomerates, through time. The majority of techniques employed here (zeta potential, particle size via DLS, fluorescence and UV-Vis spectroscopy and SEM) were shown to provide useful, complementary information on dispersion stability. Nanoparticle Tracking Analysis (NTA) provides useful, quantitative information on the concentration of nanoparticles in suspension, but is limited by its inability to accurately track the motion of large agglomerates found in the fish medium.

Dispersion stability of nanoparticles in ecotoxicological investigations: the need for adequate measurement tools

International Nuclear Information System (INIS)

Tantra, Ratna; Jing Shingheng; Pichaimuthu, Sivaraman K.; Walker, Nicholas; Noble, James; Hackley, Vincent A.

2011-01-01

One of the main challenges in nanoecotoxicological investigations is in the selection of the most suitable measurement methods and protocols for nanoparticle characterisation. Several parameters have been identified as being important as they govern nanotoxicological activity, with some parameters being better defined than others. For example, as a parameter, there is some ambiguity as to how to measure dispersion stability in the context of ecotoxicological investigations; indeed, there is disagreement over which are the best methods to measure nanoparticle dispersion stability. The purpose of this article is to use various commercially available tools to measure dispersion stability and to understand the information given by each tool. In this study, CeO 2 was dispersed in two different types of media: de-ionised water and electrolyte-containing fish medium. The DLS mean particle size of freshly dispersed sample in DI water was ∼200 nm in diameter. A visual sedimentation experiment showed that nanoparticle dispersion made in the fish medium was less stable compared to corresponding dispersion in de-ionised water. Stability of these dispersions was monitored using various techniques, for a period of 3 days. Our findings have shown that dispersion stability can be suitably assessed by monitoring: (a) surface charge, (b) sedimentation events and (c) presence of agglomerates, through time. The majority of techniques employed here (zeta potential, particle size via DLS, fluorescence and UV–Vis spectroscopy and SEM) were shown to provide useful, complementary information on dispersion stability. Nanoparticle Tracking Analysis (NTA) provides useful, quantitative information on the concentration of nanoparticles in suspension, but is limited by its inability to accurately track the motion of large agglomerates found in the fish medium.

Polymer-encapsulated metal nanoparticles: optical, structural, micro-analytical and hydrogenation studies of a composite material

International Nuclear Information System (INIS)

Scalzullo, Stefania; Mondal, Kartick; Deshmukh, Amit; Scurrell, Mike; Mallick, Kaushik; Witcomb, Mike

2008-01-01

A single-step synthesis route is described for the preparation of a metal-polymer composite in which palladium acetate and meta-amino benzoic acid were used as the precursors for palladium nanoparticles and poly(meta-amino benzoic acid) (PABA). The palladium nanoparticles were found to be uniformly dispersed and highly stabilized throughout the macromolecule matrix. The resultant composite material was characterized by means of different techniques, such as IR and Raman spectroscopy, which provided information regarding the chemical structure of the polymer, whereas electron microscopy images yielded information regarding the morphology of the composite material and the distribution of the metal particles in the composite material. The composite material was used as a catalyst for the ethylene hydrogenation reaction and showed catalytic activity at higher temperatures. TEM studies confirmed the changed environment of the nanoparticles at these temperatures

Synthesis of organically-capped metallic zinc nanoparticles using electrical explosion of wires (EEW) coupled with PIERMEN

Energy Technology Data Exchange (ETDEWEB)

Abdelkader, Elseddik M.; Jelliss, Paul A., E-mail: jellissp@slu.edu; Buckner, Steven W., E-mail: buckners@slu.edu

2015-01-15

In this study zinc nanoparticles (ZNPs) were produced using electrical explosion of wires (EEW) with NP size around 100 nm. The explosion chamber was constructed from Teflon to withstand the shockwave, to allow growth and reaction of the incipient ZNPs in various organic solvents, and to allow a constant flow of argon creating an inert atmosphere. We utilized polymerization initiation by electron-rich metallic nanoparticles (PIERMEN) as the capping technique for the reactive ZNPs. Epoxides and alkenes served as the capping monomers. Epoxide caps underwent oligomerization on the surface of the NPs to form a protective polyether cap which renders the particles stable, non-pyrophoric in air, and dispersible in organic solvents. We investigated various Zn to monomer molar ratios varying from 1:1 to 10:1. Polyethylene glycol was also used as a capping agent and was found to give the smallest average Zn core sizes with the metal core diameters varying from 15 to 20 nm. Several solvents were used to study differences in resultant particle size and we observe toluene to give the smallest metal cores. Transmission electron microscopy shows the spherical particles with the metallic core embedded in a polymer matrix. The sample consists of predominantly smaller particles, but there was also a broad size distribution giving a range of 20–150 nm. Powder X-ray diffraction (PXRD) was used to confirm the identity of the metallic NPs. The capping agents were characterized using both attenuated total reflectance-Fourier transform infra-red (ATR-FTIR) and Raman spectroscopies. There was no evidence for formation of zinc oxide with appropriate organic capping agents and solvent combinations; thus, this is the first report of production of pure metallic zinc nanoparticles with an organic cap using EEW. - Highlights: • Organically-capped Zn metal nanoparticles are produced by EEW in organic solution. • Incipient Zn metal nanoparticles initiate oligomerization of epoxide and

Surface functionalization of microwave plasma-synthesized silica nanoparticles for enhancing the stability of dispersions

Science.gov (United States)

Sehlleier, Yee Hwa; Abdali, Ali; Schnurre, Sophie Marie; Wiggers, Hartmut; Schulz, Christof

2014-08-01

Gas phase-synthesized silica nanoparticles were functionalized with three different silane coupling agents (SCAs) including amine, amine/phosphonate and octyltriethoxy functional groups and the stability of dispersions in polar and non-polar dispersing media such as water, ethanol, methanol, chloroform, benzene, and toluene was studied. Fourier transform infrared spectroscopy showed that all three SCAs are chemically attached to the surface of silica nanoparticles. Amine-functionalized particles using steric dispersion stabilization alone showed limited stability. Thus, an additional SCA with sufficiently long hydrocarbon chains and strong positively charged phosphonate groups was introduced in order to achieve electrosteric stabilization. Steric stabilization was successful with hydrophobic octyltriethoxy-functionalized silica nanoparticles in non-polar solvents. The results from dynamic light scattering measurements showed that in dispersions of amine/phosphonate- and octyltriethoxy-functionalized silica particles are dispersed on a primary particle level. Stable dispersions were successfully prepared from initially agglomerated nanoparticles synthesized in a microwave plasma reactor by designing the surface functionalization.

Synthesis of metallic nanoparticles in SiO{sub 2} matrices; Sintesis de nanoparticulas metalicas en matrices de SiO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Gutierrez W, C; Mondragon G, G; Perez H, R; Mendoza A, D [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

2004-07-01

Metallic nanoparticles was synthesized in SiO{sub 2} matrices by means of a process of two stages. The first one proceeded via sol-gel, incorporating the metallic precursors to the reaction system before the solidification of the matrix. Later on, the samples underwent a thermal treatment in atmosphere of H{sub 2}, carrying out the reduction of the metals that finally formed to the nanoparticles. Then it was detected the presence of smaller nanoparticles than 20 nm, dispersed and with the property of being liberated easily of the matrix, conserving a free surface, chemically reactive and with response to external electromagnetic radiation. The system SiO{sub 2}-Pd showed an important thermoluminescent response. (Author)

Synthesis and Characterization of Metal Sulfides Nanoparticles/Poly(methyl methacrylate Nanocomposites

Directory of Open Access Journals (Sweden)

Peter A. Ajibade

2014-01-01

Full Text Available Metal sulfides nanoparticles in poly(methyl methacrylate matrices were prepared and characterized by infrared spectroscopy, thermogravimetric analysis, powder X-ray diffraction, scanning electron microscope (SEM, and transmission electron microscope (TEM. The FTIR confirms the dispersion of the nanoparticles in PMMA matrices with the C=O and C–O–C bonds of the PMMA shifting slightly which may be attributed to the interactions between the nanoparticles and PMMA. The ZnS nanoparticles in PMMA have average crystallite sizes of 4–7 nm while the CdS has particle size of 10 nm and HgS has crystallite sizes of 8–20 nm. The increasing order of particle sizes as calculated from the XRD is ZnS/PMMA

Same magnetic nanoparticles, different heating behavior: Influence of the arrangement and dispersive medium

Energy Technology Data Exchange (ETDEWEB)

Andreu, Irene [Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Campus Río Ebro, María de Luna, 3, 50018 Zaragoza (Spain); Natividad, Eva, E-mail: evanat@unizar.es [Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Campus Río Ebro, María de Luna, 3, 50018 Zaragoza (Spain); Solozábal, Laura [Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Campus Río Ebro, María de Luna, 3, 50018 Zaragoza (Spain); Roubeau, Olivier [Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Departamento de Física de la Materia Condensada, 50009 Zaragoza (Spain)

2015-04-15

The heating ability of the same magnetic nanoparticles (MNPs) dispersed in different media has been studied in the 170–310 K temperature range. For this purpose, the biggest non-twinned nanoparticles have been selected among a series of magnetite nanoparticles of increasing sizes synthesized via a seeded growth method. The sample with nanoparticles dispersed in n-tetracosane, thermally quenched from 100 °C and solid in the whole measuring range, follows the linear response theoretical behavior for non-interacting nanoparticles, and displays a remarkably large maximum specific absorption rate (SAR) value comparable to that of magnetosomes at the alternating magnetic fields used in the measurements. The other samples, with nanoparticles dispersed either in alkane solvents of sub-ambient melting temperatures or in epoxy resin, display different thermal behaviors and maximum SAR values ranging between 11 and 65% of that achieved for the sample with n-tetracosane as dispersive medium. These results highlight the importance of the MNPs environment and arrangement to maintain optimal SAR values, and may help to understand the disparity sometimes found between MNPs heating performance measured in a ferrofluid and after injection in an animal model, where MNP arrangement and environment are not the same. - Highlights: • We synthetize a series of Fe{sub 3}O{sub 4} nanoparticles by the seeded-growth method. • We characterize the heating ability of 13.9 nm particles dispersed in several media. • We apply SAR(T) characterization to locate the onset of superparamagnetic behavior. • The highest SAR values are obtained in low-concentration solid-alkane dispersion. • Acquired arrangements in different media strongly modify SAR trends and values.

Metallic Magnetic Nanoparticles

Directory of Open Access Journals (Sweden)

A. Hernando

2005-01-01

Full Text Available In this paper, we reviewed some relevant aspects of the magnetic properties of metallic nanoparticles with small size (below 4 nm, covering the size effects in nanoparticles of magnetic materials, as well as the appearance of magnetism at the nanoscale in materials that are nonferromagnetic in bulk. These results are distributed along the text that has been organized around three important items: fundamental magnetic properties, different fabrication procedures, and characterization techniques. A general introduction and some experimental results recently obtained in Pd and Au nanoparticles have also been included. Finally, the more promising applications of magnetic nanoparticles in biomedicine are indicated. Special care was taken to complete the literature available on the subject.

Biomolecule-coated metal nanoparticles on titanium.

Science.gov (United States)

Christensen, Stephen L; Chatt, Amares; Zhang, Peng

2012-02-07

Immobilizations of nanoparticles and biomolecules on biocompatible substrates such as titanium are two promising approaches to bringing new functionalities to Ti-based biomaterials. Herein, we used a variety of X-ray spectroscopic techniques to study and better understand metal-thiolate interactions in biofunctionalized metal nanoparticle systems supported on Ti substrates. Using a facile one-step procedure, a series of Au nanoparticle samples with varied biomolecule coatings ((2-mercatopropionyl)glycine (MPG) and bovine serum albumin (BSA)) and biomolecule concentrations are prepared. Ag and Pd systems are also studied to observe change with varying metal composition. The structure and properties of these biomolecule-coated nanoparticles are investigated with scanning electron microscopy (SEM) and element-specific X-ray techniques, including extended X-ray absorption fine structure (Au L(3)-edge), X-ray absorption near-edge structure (Au L(3), Ag L(3), Pd L(3), and S K-edge), and X-ray photoelectron spectroscopy (Au 4f, Ag 3d, Pd 3d, and S 2p core level). It was found that, by comparison of SEM and X-ray spectroscopy results, the coating of metal nanoparticles with varying model biomolecule systems can have a significant effect on both surface coverage and organization. This work offers a facile chemical method for bio- and nanofunctionalization of Ti substrates as well as provides a physical picture of the structure and bonding of biocoated metal nanoparticles, which may lead to useful applications in orthopedics and biomedicine.

Effects of nickel-oxide nanoparticle pre-exposure dispersion status on bioactivity in the mouse lung.

Science.gov (United States)

Sager, Tina; Wolfarth, Michael; Keane, Michael; Porter, Dale; Castranova, Vincent; Holian, Andrij

2016-01-01

Nanotechnology is emerging as one of the world's most promising new technologies. From a toxicology perspective, nanoparticles possess two features that promote their bioactivity. The first involves physical-chemical characteristics of the nanoparticle, which include the surface area of the nanoparticle. The second feature is the ability of the nanoparticle to traverse cell membranes. These two important nanoparticle characteristics are greatly influenced by placing nanoparticles in liquid medium prior to animal exposure. Nanoparticles tend to agglomerate and clump in suspension, making it difficult to reproducibly deliver them for in vivo or in vitro experiments, possibly affecting experimental variability. Thus, we hypothesize that nanoparticle dispersion status will correlate with the in vivo bioactivity/toxicity of the particle. To test our hypothesis, nano-sized nickel oxide was suspended in four different dispersion media (phosphate-buffered saline (PBS), dispersion medium (DM), a combination of dipalmitoyl-phosphatidyl choline (DPPC) and albumin in concentrations that mimic diluted alveolar lining fluid), Survanta®, or pluronic (Pluronic F-68). Well-dispersed and poorly dispersed suspensions were generated in each media by varying sonication time on ice utilizing a Branson Sonifer 450 (25W continuous output, 20 min or 5 min, respectively). Mice (male, C57BL/6J, 7-weeks-old) were given 0-80 µg/mouse of nano-sized nickel oxide in the different states of dispersion via pharyngeal aspiration. At 1 and 7 d post-exposure, mice underwent whole lung lavage to assess pulmonary inflammation and injury as a function of dispersion status, dose and time. The results show that pre-exposure dispersion status correlates with pulmonary inflammation and injury. These results indicate that a greater degree of pre-exposure dispersion increases pulmonary inflammation and cytotoxicity, as well as decreases in the integrity of the blood-gas barrier in the lung.

Structure and crystallinity of water dispersible photoactive nanoparticles for organic solar cells

DEFF Research Database (Denmark)

Pedersen, Emil Bøje Lind; Pedersen, M.C.; Simonsen, Søren Bredmose

2015-01-01

Water based inks would be a strong advantage for large scale production of organic photovoltaic devices. Formation of water dispersible nanoparticles produced by the Landfester method is a promising route to achieve such inks. We provide new insights into the key ink properties of poly(3-hexylthi......Water based inks would be a strong advantage for large scale production of organic photovoltaic devices. Formation of water dispersible nanoparticles produced by the Landfester method is a promising route to achieve such inks. We provide new insights into the key ink properties of poly(3......-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) nanoparticles such as the internal structure and crystallinity of the dispersed nanoparticles and the previously unreported drastic changes that occur when the inks are cast into a film. We observe through transmission electron...

Development of megestrol acetate solid dispersion nanoparticles for enhanced oral delivery by using a supercritical antisolvent process.

Science.gov (United States)

Ha, Eun-Sol; Kim, Jeong-Soo; Baek, In-Hwan; Yoo, Jin-Wook; Jung, Yunjin; Moon, Hyung Ryong; Kim, Min-Soo

2015-01-01

In the present study, solid dispersion nanoparticles with a hydrophilic polymer and surfactant were developed using the supercritical antisolvent (SAS) process to improve the dissolution and oral absorption of megestrol acetate. The physicochemical properties of the megestrol acetate solid dispersion nanoparticles were characterized using scanning electron microscopy, differential scanning calorimetry, powder X-ray diffraction, and a particle-size analyzer. The dissolution and oral bioavailability of the nanoparticles were also evaluated in rats. The mean particle size of all solid dispersion nanoparticles that were prepared was nanoparticles. Hydroxypropylmethyl cellulose (HPMC) solid dispersion nanoparticles significantly increased the maximum dissolution when compared with polyvinylpyrrolidone K30 solid dispersion nanoparticles. The extent and rate of dissolution of megestrol acetate increased after the addition of a surfactant into the HPMC solid dispersion nanoparticles. The most effective surfactant was Ryoto sugar ester L1695, followed by D-α-tocopheryl polyethylene glycol 1000 succinate. In this study, the solid dispersion nanoparticles with a drug:HPMC:Ryoto sugar ester L1695 ratio of 1:2:1 showed >95% rapid dissolution within 30 minutes, in addition to good oral bioavailability, with approximately 4.0- and 5.5-fold higher area under the curve (0-24 hours) and maximum concentration, respectively, than raw megestrol acetate powder. These results suggest that the preparation of megestrol acetate solid dispersion nanoparticles using the supercritical antisolvent process is a promising approach to improve the dissolution and absorption properties of megestrol acetate.

Biomedical applications of green synthesized Nobel metal nanoparticles.

Science.gov (United States)

Khan, Zia Ul Haq; Khan, Amjad; Chen, Yongmei; Shah, Noor S; Muhammad, Nawshad; Khan, Arif Ullah; Tahir, Kamran; Khan, Faheem Ullah; Murtaza, Behzad; Hassan, Sadaf Ul; Qaisrani, Saeed Ahmad; Wan, Pingyu

2017-08-01

Synthesis of Nobel metal nanoparticles, play a key role in the field of medicine. Plants contain a substantial number of organic constituents, like phenolic compounds and various types of glycosides that help in synthesis of metal nanoparticles. Synthesis of metal nanoparticles by green method is one of the best and environment friendly methods. The major significance of the green synthesis is lack of toxic by-products produced during metal nanoparticle synthesis. The nanoparticles, synthesized by green method show various significant biological activities. Most of the research articles report the synthesized nanoparticles to be active against gram positive and gram negative bacteria. Some of these bacteria include Escherichia coli, Bacillus subtilis, Klebsiella pneumonia and Pseudomonas fluorescens. The synthesized nanoparticles also show significant antifungal activity against Trichophyton simii, Trichophyton mentagrophytes and Trichophyton rubrum as well as different types of cancer cells such as breast cancer cell line. They also exhibit significant antioxidant activity. The activities of these Nobel metal nano-particles mainly depend on the size and shape. The particles of small size with large surface area show good activity in the field of medicine. The synthesized nanoparticles are also active against leishmanial diseases. This research article explores in detail the green synthesis of the nanoparticles and their uses thereof. Copyright © 2017 Elsevier B.V. All rights reserved.

Laser assisted embedding of nanoparticles into metallic materials

International Nuclear Information System (INIS)

Lin Dong; Suslov, Sergey; Ye Chang; Liao Yiliang; Liu, C. Richard; Cheng, Gary J.

2012-01-01

This paper reports a methodology of half-embedding nanoparticles into metallic materials. Transparent and opaque nanoparticles are chosen to demonstrate the process of laser assisted nanoparticle embedding. Dip coating method is used to coat transparent or opaque nanoparticle on the surface of metallic material. Nanoparticles are embedded into substrate by laser irradiation. In this study, the mechanism and process of nanoparticle embedding are investigated. It is found both transparent and opaque nanoparticles embedding are with high densities and good uniformities.

Diffusive dynamics of nanoparticles in aqueous dispersions

KAUST Repository

He, Kai; Spannuth, Melissa; Conrad, Jacinta C.; Krishnamoorti, Ramanan

2012-01-01

The diffusive dynamics of 100 nm to 400 nm diameter polystyrene nanoparticles dispersed in water were studied using brightfield and fluorescence based differential dynamic microscopy (DDM) and compared to those obtained from dynamic light scattering. The relaxation times measured with brightfield and fluorescence DDM over a broad range of concentration of nanoparticles (10 -6 ≤ φ ≤ 10-3) and scattering vectors (0.5 μm-1 < q < 10 μm-1) are in excellent agreement with each other and extrapolate quantitatively to those obtained from DLS measurements. The diffusion coefficients extracted from the q-dependent relaxation times using all three methods are independent of the nanoparticle concentration. © 2012 The Royal Society of Chemistry.

Microbial exopolysaccharide-mediated synthesis and stabilization of metal nanoparticles.

Science.gov (United States)

Sathiyanarayanan, Ganesan; Dineshkumar, Krishnamoorthy; Yang, Yung-Hun

2017-11-01

Exopolysaccharides (EPSs) are structurally and functionally valuable biopolymer secreted by different prokaryotic and eukaryotic microorganisms in response to biotic/abiotic stresses and to survive in extreme environments. Microbial EPSs are fascinating in various industrial sectors due to their excellent material properties and less toxic, highly biodegradable, and biocompatible nature. Recently, microbial EPSs have been used as a potential template for the rapid synthesis of metallic nanoparticles and EPS-mediated metal reduction processes are emerging as simple, harmless, and environmentally benign green chemistry approaches. EPS-mediated synthesis of metal nanoparticles is a distinctive metabolism-independent bio-reduction process due to the formation of interfaces between metal cations and the polyanionic functional groups (i.e. hydroxyl, carboxyl and amino groups) of the EPS. In addition, the range of physicochemical features which facilitates the EPS as an efficient stabilizing or capping agents to protect the primary structure of the metal nanoparticles with an encapsulation film in order to separate the nanoparticle core from the mixture of composites. The EPS-capping also enables the further modification of metal nanoparticles with expected material properties for multifarious applications. The present review discusses the microbial EPS-mediated green synthesis/stabilization of metal nanoparticles, possible mechanisms involved in EPS-mediated metal reduction, and application prospects of EPS-based metal nanoparticles.

Retardation effects on the dispersion and propagation of plasmons in metallic nanoparticle chains

Science.gov (United States)

Downing, Charles A.; Mariani, Eros; Weick, Guillaume

2018-01-01

We consider a chain of regularly-spaced spherical metallic nanoparticles, where each particle supports three degenerate localized surface plasmons. Due to the dipolar interaction between the nanoparticles, the localized plasmons couple to form extended collective modes. Using an open quantum system approach in which the collective plasmons are interacting with vacuum electromagnetic modes and which, importantly, readily incorporates retardation via the light-matter coupling, we analytically evaluate the resulting radiative frequency shifts of the plasmonic bandstructure. For subwavelength-sized nanoparticles, our analytical treatment provides an excellent quantitative agreement with the results stemming from laborious numerical calculations based on fully-retarded solutions to Maxwell’s equations. Indeed, the explicit expressions for the plasmonic spectrum which we provide showcase how including retardation gives rise to a logarithmic singularity in the bandstructure of transverse-polarized plasmons. We further study the impact of retardation effects on the propagation of plasmonic excitations along the chain. While for the longitudinal modes, retardation has a negligible effect, we find that the retarded dipolar interaction can significantly modify the plasmon propagation in the case of transverse-polarized modes. Moreover, our results elucidate the analogy between radiative effects in nanoplasmonic systems and the cooperative Lamb shift in atomic physics.

Surface modification and functionalization of metal and metal oxide nanoparticles by organic ligands

NARCIS (Netherlands)

Neouze, M.A.; Schubert, U.S.

2008-01-01

Metal or metal oxide nanoparticles possess unique features compared to equivalent larger-scale materials. For applications, it is often necessary to stabilize or functionalize such nanoparticles. Thus, modification of the surface of nanoparticles is an important chemical challenge. In this survey,

New Nanoparticles Dispersing Beads Mill with Ultra Small Beads and its Application

International Nuclear Information System (INIS)

Inkyo, M; Tahara, T; Imajyo, Y

2011-01-01

Two of the major problems related to nanoparticle dispersion with a conventional beads mill are re-agglomeration and damage to the crystalline structure of the particles. The Ultra Apex Mill was developed to solve these problems by enabling the use of ultra-small beads with a diameter of less than 0.1mm. The core of this breakthrough development is centrifugation technology which allows the use of beads as small as 0.015mm. When dispersing agglomerated nanoparticles the impulse of the small beads is very low which means there is little influence on the particles. The surface energy of the nanoparticles remains low so the properties are not likely to change. As a result, stable nanoparticle dispersions can be achieved without re-cohesion. The Ultra Apex Mill is superior to conventional beads mills that are limited to much larger bead sizes. The technology of the Ultra Apex Mill has pioneered practical applications for nanoparticles in various fields: composition materials for LCD screens, ink-jet printing, ceramic condensers and cosmetics.

Structure and properties of nanoparticles fabricated by laser ablation of Zn metal targets in water and ethanol

Science.gov (United States)

Svetlichnyi, V. A.; Lapin, I. N.

2013-10-01

Size characteristics, structure, and spectral and luminescent properties of nanoparticles fabricated by laser ablation of zinc metal targets in water and ethanol are experimentally investigated upon excitation by Nd:YAG-laser radiation (1064 nm, 7 ns, and 15 Hz). It is demonstrated that zinc oxide nanoparticles with average sizes of 10 nm (in water) and 16 nm (in ethanol) are formed in the initial stage as a result of ablation. The kinetics of the absorption and luminescence spectra, transmission electron microscopy, and x-ray structural analysis demonstrate that during long storage of water dispersions and their drying, nanoparticles efficiently interact with carbon dioxide gas of air that leads to the formation of water-soluble Zn(CO3)2(OH)6. In ethanol, Zn oxidation leads to the formation of stable dispersions of ZnO nanoparticles with 99% of the wurtzite phase; in this case, the fluorescence spectra of ZnO nanoparticles change with time, shifting toward longer wavelength region from 550 to 620 nm, which is caused by the changed nature of defects.

Genotoxicity of metal nanoparticles.

Science.gov (United States)

Xie, Hong; Mason, Michael M; Wise, John Pierce

2011-01-01

Nanotechnology is currently used in industry, medicine, and military applications, as well as in more than 300 commercial products. Yet, the same properties that make these particles exciting for technology also make them daunting public health concerns because their toxicity is unknown and relatively unexplored. Increased attention is being placed on the study of metal particle genotoxicity; however, a lot of unknowns remain about their effects and the mechanisms. In this article, we highlight some metal and metal oxide nanoparticles of interest and discuss the current in vivo and in vitro studies of genotoxic effects. Many metal nanoparticles were found to cause chromosomal aberrations, DNA strand breaks, oxidative DNA damage, and mutations. Inconsistencies are found in the literature, however, thus drawing conclusions is difficult due to a variety of factors. Therefore, the areas requiring further attention are highlighted and recommendations to improve our understanding of the genotoxic potential are addressed.

Synthesis of novel cellulose- based antibacterial composites of Ag nanoparticles@ metal-organic frameworks@ carboxymethylated fibers.

Science.gov (United States)

Duan, Chao; Meng, Jingru; Wang, Xinqi; Meng, Xin; Sun, Xiaole; Xu, Yongjian; Zhao, Wei; Ni, Yonghao

2018-08-01

A novel cellulose-based antibacterial material, namely silver nanoparticles@ metal-organic frameworks@ carboxymethylated fibers composites (Ag NPs@ HKUST-1@ CFs), was synthesized. The results showed that the metal-organic frameworks (HKUST-1) were uniformly anchored on the fiber's surfaces by virtue of complexation between copper ions in HKUST-1 and carboxyl groups on the carboxymethylated fibers (CFs). The silver nanoparticles (Ag NPs) were immobilized and well-dispersed into the pores and/or onto the surfaces of HKUST-1 via in situ microwave reduction, resulting in the formation of novel Ag NPs@ HKUST-1@ CFs composites. The antibacterial assays showed that the as-prepared composites exhibited a much higher antibacterial activity than Ag NPs@ CFs or HKUST-1@ CFs samples. Copyright © 2018 Elsevier Ltd. All rights reserved.

Water-dispersible nanoparticles via interdigitation of sodium ...

Indian Academy of Sciences (India)

Unknown

Abstract. This paper describes the formation of water-dispersible gold nano- particles capped with a bilayer of sodium dodecylsulphate (SDS) and octadecylamine. (ODA) molecules. Vigorous shaking of a biphasic mixture consisting of ODA-capped gold nanoparticles in chloroform and SDS in water results in the rapid ...

Dispersion and stabilization of cochleate nanoparticles.

Science.gov (United States)

Bozó, Tamás; Wacha, András; Mihály, Judith; Bóta, Attila; Kellermayer, Miklós S Z

2017-08-01

Cochleates, calcium-stabilized membrane rolls of nanoscale diameter, promise a unique and efficient way of delivering lipid-soluble drugs, proteins or nucleic acids into biological systems because they protect the encapsulated material against enzymatic or chemical degradation. Self-aggregation, which typically arises during production and storage is a major obstacle that has so far precluded the development of an efficient cochleate-based drug-delivery system. Here we show that citric acid, added transiently in a narrow concentration range, effectively disperses cochleate aggregates, stabilizes the disperse state for long-term storage and preserves the canonical ultrastructure and topological characteristics of cochleate nanoparticles. Copyright © 2017 Elsevier B.V. All rights reserved.

Trends in the Microwave-Assisted Synthesis of Metal Oxide Nanoparticles Supported on Carbon Nano tubes and Their Applications

International Nuclear Information System (INIS)

Motshekga, S.C.; Pillai, S.K.; Ray, S.S.; Motshekga, S.C.; Ray, S.S.; Jalama, K.; Krause, Rui.W.M.

2012-01-01

The study of coating carbon nano tubes with metal/oxides nanoparticles is now becoming a promising and challenging area of research. To optimize the use of carbon nano tubes in various applications, it is necessary to attach functional groups or other nano structures to their surface. The combination of the distinctive properties of carbon nano tubes and metal/oxides is expected to be applied in field emission displays, nano electronic devices, novel catalysts, and polymer or ceramic reinforcement. The synthesis of these composites is still largely based on conventional techniques, such as wet impregnation followed by chemical reduction of the metal nanoparticle precursors. These techniques based on thermal heating can be time consuming and often lack control of particle size and morphology. Hence, there is interest in microwave technology recently, where using microwaves represents an alternative way of power input into chemical reactions through dielectric heating. This paper covers the synthesis and applications of carbon-nano tube-coated metal/oxides nanoparticles prepared by a microwave-assisted method. The reviewed studies show that the microwave-assisted synthesis of the composites allows processes to be completed within a shorter reaction time with uniform and well-dispersed nanoparticle formation.

Recent Trends in the Microwave-Assisted Synthesis of Metal Oxide Nanoparticles Supported on Carbon Nanotubes and Their Applications

Directory of Open Access Journals (Sweden)

Sarah C. Motshekga

2012-01-01

Full Text Available The study of coating carbon nanotubes with metal/oxides nanoparticles is now becoming a promising and challenging area of research. To optimize the use of carbon nanotubes in various applications, it is necessary to attach functional groups or other nanostructures to their surface. The combination of the distinctive properties of carbon nanotubes and metal/oxides is expected to be applied in field emission displays, nanoelectronic devices, novel catalysts, and polymer or ceramic reinforcement. The synthesis of these composites is still largely based on conventional techniques, such as wet impregnation followed by chemical reduction of the metal nanoparticle precursors. These techniques based on thermal heating can be time consuming and often lack control of particle size and morphology. Hence, there is interest in microwave technology recently, where using microwaves represents an alternative way of power input into chemical reactions through dielectric heating. This paper covers the synthesis and applications of carbon-nanotube-coated metal/oxides nanoparticles prepared by a microwave-assisted method. The reviewed studies show that the microwave-assisted synthesis of the composites allows processes to be completed within a shorter reaction time with uniform and well-dispersed nanoparticle formation.

Surface free energy of alkali and transition metal nanoparticles

International Nuclear Information System (INIS)

Aqra, Fathi; Ayyad, Ahmed

2014-01-01

Graphical abstract: Size dependent surface free energy of spherical, cubic and disk Au nanoparticles. - Highlights: • A model to account for the surface free energy of metallic nanoparticles is described. • The model requires only the cohesive energy of the nanoparticle. • The surface free energy of a number of metallic nanoparticles has been calculated, and the obtained values agree well with existing data. • Surface energy falls down very fast when the number of atoms is less than hundred. • The model is applicable to any metallic nanoparticle. - Abstract: This paper addresses an interesting issue on the surface free energy of metallic nanoparticles as compared to the bulk material. Starting from a previously reported equation, a theoretical model, that involves a specific term for calculating the cohesive energy of nanoparticle, is established in a view to describe the behavior of surface free energy of metallic nanoparticles (using different shapes of particle: sphere, cube and disc). The results indicate that the behavior of surface energy is very appropriate for spherical nanoparticle, and thus, it is the most realistic shape of a nanoparticle. The surface energy of copper, silver, gold, platinum, tungsten, molybdenum, tantalum, paladium and alkali metallic nanoparticles is only prominent in the nanoscale size, and it decreases with the decrease of nanoparticle size. Thus, the surface free energy plays a more important role in determining the properties of nanoparticles than in bulk materials. It differs from shape to another, and falls down as the number of atoms (nanoparticle size) decreases. In the case of spherical nanoparticles, the onset of the sharp decrease in surface energy is observed at about 110 atom. A decrease of 16% and 45% in surface energy is found by moving from bulk to 110 atom and from bulk to 5 atom, respectively. The predictions are consistent with the reported data

A general chelate-assisted co-assembly to metallic nanoparticles-incorporated ordered mesoporous carbon catalysts for Fischer-Tropsch synthesis.

Science.gov (United States)

Sun, Zhenkun; Sun, Bo; Qiao, Minghua; Wei, Jing; Yue, Qin; Wang, Chun; Deng, Yonghui; Kaliaguine, Serge; Zhao, Dongyuan

2012-10-24

The organization of different nano objects with tunable sizes, morphologies, and functions into integrated nanostructures is critical to the development of novel nanosystems that display high performances in sensing, catalysis, and so on. Herein, using acetylacetone as a chelating agent, phenolic resol as a carbon source, metal nitrates as metal sources, and amphiphilic copolymers as a template, we demonstrate a chelate-assisted multicomponent coassembly method to synthesize ordered mesoporous carbon with uniform metal-containing nanoparticles. The obtained nanocomposites have a 2-D hexagonally arranged pore structure, uniform pore size (~4.0 nm), high surface area (~500 m(2)/g), moderate pore volume (~0.30 cm(3)/g), uniform and highly dispersed Fe(2)O(3) nanoparticles, and constant Fe(2)O(3) contents around 10 wt %. By adjusting acetylacetone amount, the size of Fe(2)O(3) nanoparticles is readily tunable from 8.3 to 22.1 nm. More importantly, it is found that the metal-containing nanoparticles are partially embedded in the carbon framework with the remaining part exposed in the mesopore channels. This unique semiexposure structure not only provides an excellent confinement effect and exposed surface for catalysis but also helps to tightly trap the nanoparticles and prevent aggregating during catalysis. Fischer-Tropsch synthesis results show that as the size of iron nanoparticles decreases, the mesoporous Fe-carbon nanocomposites exhibit significantly improved catalytic performances with C(5+) selectivity up to 68%, much better than any reported promoter-free Fe-based catalysts due to the unique semiexposure morphology of metal-containing nanoparticles confined in the mesoporous carbon matrix.

Development of megestrol acetate solid dispersion nanoparticles for enhanced oral delivery by using a supercritical antisolvent process

Directory of Open Access Journals (Sweden)

Ha ES

2015-08-01

Full Text Available Eun-Sol Ha,1 Jeong-Soo Kim,2 In-hwan Baek,3 Jin-Wook Yoo,1 Yunjin Jung,1 Hyung Ryong Moon,1 Min-Soo Kim1 1College of Pharmacy, Pusan National University, 2Dong-A ST Co Ltd, Yongin, 3College of Pharmacy, Kyungsung University, Busan, South Korea Abstract: In the present study, solid dispersion nanoparticles with a hydrophilic polymer and surfactant were developed using the supercritical antisolvent (SAS process to improve the dissolution and oral absorption of megestrol acetate. The physicochemical properties of the megestrol acetate solid dispersion nanoparticles were characterized using scanning electron microscopy, differential scanning calorimetry, powder X-ray diffraction, and a particle-size analyzer. The dissolution and oral bioavailability of the nanoparticles were also evaluated in rats. The mean particle size of all solid dispersion nanoparticles that were prepared was <500 nm. Powder X-ray diffraction and differential scanning calorimetry measurements showed that megestrol acetate was present in an amorphous or molecular dispersion state within the solid dispersion nanoparticles. Hydroxypropylmethyl cellulose (HPMC solid dispersion nanoparticles significantly increased the maximum dissolution when compared with polyvinylpyrrolidone K30 solid dispersion nanoparticles. The extent and rate of dissolution of megestrol acetate increased after the addition of a surfactant into the HPMC solid dispersion nanoparticles. The most effective surfactant was Ryoto sugar ester L1695, followed by d-a-tocopheryl polyethylene glycol 1000 succinate. In this study, the solid dispersion nanoparticles with a drug:HPMC:Ryoto sugar ester L1695 ratio of 1:2:1 showed >95% rapid dissolution within 30 minutes, in addition to good oral bioavailability, with approximately 4.0- and 5.5-fold higher area under the curve (0–24 hours and maximum concentration, respectively, than raw megestrol acetate powder. These results suggest that the preparation of megestrol

Synthesis and Characterization of Iron Oxide Nanoparticles and Applications in the Removal of Heavy Metals from Industrial Wastewater

Directory of Open Access Journals (Sweden)

Zuolian Cheng

2012-01-01

Full Text Available This study investigated the applicability of maghemite (γ-Fe2O3 nanoparticles for the selective removal of toxic heavy metals from electroplating wastewater. The maghemite nanoparticles of 60 nm were synthesized using a coprecipitation method and characterized by X-ray diffraction (XRD and scanning electron microscopy (SEM equipped with energy dispersive X-ray spectroscopy (EDX. Batch experiments were carried out for the removal of Pb2+ ions from aqueous solutions by maghemite nanoparticles. The effects of contact time, initial concentration of Pb2+ ions, solution pH, and salinity on the amount of Pb2+ removed were investigated. The adsorption process was found to be highly pH dependent, which made the nanoparticles selectively adsorb this metal from wastewater. The adsorption of Pb2+ reached equilibrium rapidly within 15 min and the adsorption data were well fitted with the Langmuir isotherm.

Dispersion and Stabilization of Photocatalytic TiO2 Nanoparticles in Aqueous Suspension for Coatings Applications

Directory of Open Access Journals (Sweden)

Siti Hajar Othman

2012-01-01

Full Text Available To produce titanium dioxide (TiO2 nanoparticle coatings, it is desirable that the nanoparticles are dispersed into a liquid solution and remain stable for a certain period of time. Controlling the dispersion and aggregation of the nanoparticles is crucial to exploit the advantages of the nanometer-sized TiO2 particles. In this work, TiO2 nanoparticles were dispersed and stabilized in aqueous suspensions using two common dispersants which were polyacrylic acid (PAA and ammonium polymethacrylate (Darvan C. The effect of parameters such as ultrasonication amplitude and type and amount of dispersants on the dispersibility and stability of the TiO2 aqueous suspensions were examined. Rupture followed by erosion was determined to be the main break up mechanisms when ultrasonication was employed. The addition of dispersant was found to produce more dispersed and more stabilized aqueous suspension. 3 wt.% of PAA with average molecular weight (Mw of 2000 g/mol (PAA 2000 was determined to produce the best and most stable dispersion. The suspensions were then coated on quartz glass, whereby the photocatalytic activity of the coatings was studied via the degradation of formaldehyde gas under UV light. The coatings were demonstrated to be photocatalytically active.

Interference between nanoparticles and metal homeostasis

International Nuclear Information System (INIS)

Petit, A N; Catty, P; Charbonnier, P; Cuillel, M; Mintz, E; Moulis, J M; Niviere, V; Choudens, S Ollagnier de; Garcia, C Aude; Candeias, S; Chevallet, M; Collin-Faure, V; Lelong, C; Luche, S; Rabilloud, T; Casanova, A; Herlin-Boime, N; Douki, T; Ravanat, J L; Sauvaigo, S

2011-01-01

The TiO 2 nanoparticles (NPs) are now produced abundantly and widely used in a variety of consumer products. Due to the important increase in the production of TiO 2 -NPs, potential widespread exposure of humans and environment may occur during both the manufacturing process and final use. Therefore, the potential toxicity of TiO 2 -NPs on human health and environment has attracted particular attention. Unfortunately, the results of the large number of studies on the toxicity of TiO 2 -NPs differ significantly, mainly due to an incomplete characterization of the used nanomaterials in terms of size, shape and crystalline structure and to their unknown state of agglomeration/aggregation. The purpose of our project entitled NanoBioMet is to investigate if interferences between nanoparticles and metal homeostasis could be observed and to study the toxicity mechanisms of TiO 2 -NPs with well-characterized physicochemical parameters, using proteomic and molecular approaches. A perturbation of metal homeostasis will be evaluated upon TiO 2 -NPs exposure which could generate reactive oxygen species (ROS) production. Moreover, oxidative stress consequences such as DNA damage and lipid peroxidation will be studied. The toxicity of TiO 2 -NPs of different sizes and crystalline structures will be evaluated both in prokaryotic (E. coli) and eukaryotic cells (A549 human pneumocytes, macrophages, and hepatocytes). First results of the project will be presented concerning the dispersion of TiO 2 -NPs in bacterial medium, proteomic studies on total extracts of macrophages and genotoxicity on pneumocytes.

Electrostatically assisted fabrication of silver-dielectric core/shell nanoparticles thin film capacitor with uniform metal nanoparticle distribution and controlled spacing.

Science.gov (United States)

Li, Xue; Niitsoo, Olivia; Couzis, Alexander

2016-03-01

An electrostatically-assisted strategy for fabrication of thin film composite capacitors with controllable dielectric constant (k) has been developed. The capacitor is composed of metal-dielectric core/shell nanoparticle (silver/silica, Ag@SiO2) multilayer films, and a backfilling polymer. Compared with the simple metal particle-polymer mixtures where the metal nanoparticles (NP) are randomly dispersed in the polymer matrix, the metal volume fraction in our capacitor was significantly increased, owing to the densely packed NP multilayers formed by the electrostatically assisted assembly process. Moreover, the insulating layer of silica shell provides a potential barrier that reduces the tunneling current between neighboring Ag cores, endowing the core/shell nanocomposites with a stable and relatively high dielectric constant (k) and low dielectric loss (D). Our work also shows that the thickness of the SiO2 shell plays a dominant role in controlling the dielectric properties of the nanocomposites. Control over metal NP separation distance was realized not only by variation the shell thickness of the core/shell NPs but also by introducing a high k nanoparticle, barium strontium titanate (BST) of relatively smaller size (∼8nm) compared to 80-160nm of the core/shell Ag@SiO2 NPs. The BST assemble between the Ag@SiO2 and fill the void space between the closely packed core/shell NPs leading to significant enhancement of the dielectric constant. This electrostatically assisted assembly method is promising for generating multilayer films of a large variety of NPs over large areas at low cost. Copyright © 2015 Elsevier Inc. All rights reserved.

Formulation, Characterization, and in Vivo Evaluation of Celecoxib-PVP Solid Dispersion Nanoparticles Using Supercritical Antisolvent Process

Directory of Open Access Journals (Sweden)

Eun-Sol Ha

2014-12-01

Full Text Available The aim of this study was to develop celecoxib-polyvinylpyrrolidone (PVP solid dispersion nanoparticles with and without surfactant using the supercritical antisolvent (SAS process. The effect of different surfactants such as gelucire 44/14, poloxamer 188, poloxamer 407, Ryoto sugar ester L1695, and d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS on nanoparticle formation and dissolution as well as oral absorption of celecoxib-PVP K30 solid dispersion nanoparticles was investigated. Spherical celecoxib solid dispersion nanoparticles less than 300 nm in size were successfully developed using the SAS process. Analysis by differential scanning calorimetry and powder X-ray diffraction showed that celecoxib existed in the amorphous form within the solid dispersion nanoparticles fabricated using the SAS process. The celecoxib-PVP-TPGS solid dispersion nanoparticles significantly enhanced in vitro dissolution and oral absorption of celecoxib relative to that of the unprocessed form. The area under the concentration-time curve (AUC0→24 h and peak plasma concentration (Cmax increased 4.6 and 5.7 times, respectively, with the celecoxib-PVP-TPGS formulation. In addition, in vitro dissolution efficiency was well correlated with in vivo pharmacokinetic parameters. The present study demonstrated that formulation of celecoxib-PVP-TPGS solid dispersion nanoparticles using the SAS process is a highly effective strategy for enhancing the bioavailability of poorly water-soluble celecoxib.

Enhanced Electrochemical Hydrogen Storage Performance on the Porous Graphene Network Immobilizing Cobalt Metal Nanoparticle

Energy Technology Data Exchange (ETDEWEB)

Kang, Myunggoo; Lee, Dong Heon; Jung, Hyun [Dongguk University, Seoul (Korea, Republic of)

2016-05-15

In this study, we attempted to apply Co metal nanoparticles decorated on the surface of the porous graphene (Co-PG) as the electrochemical hydrogen storage system. Co-PG was successfully synthesized by the soft-template method. To determine the synthetic strategy of porous graphene and Co nanoparticles, we compare the obtained Co-PG with two different materials such as Co nanoparticle decorated reduced graphene oxide without soft-template (Co-RGO) and porous graphene without Co nanoparticle (PG). The experimental details regarding the synthesis and characterization of the Co-PG, Co-RGO, and PG samples are provided in Supporting Information. Co-PG with interpenetrating porous networks and immobilized Co metal nanoparticles were successfully synthesized by the soft-template method. The obtained Co-PG exhibited high-surface area with ink-bottle open pores owing to the homogeneous dispersion of P123 micellar rods. The XRD and FE-SEM analyses clearly confirm that Co nanoparticles were immobilized on to the surface of porous graphene without any significant aggregation. The as-obtained Co-PG showed good electrochemical performance such as capacity and cycle stability for hydrogen storage. Based on these results, we believe that the Co-PG with a high-specific surface area could be worthwhile to investigate as not only electrochemical hydrogen storage materials but also other energy storage applications.

Enhanced Electrochemical Hydrogen Storage Performance on the Porous Graphene Network Immobilizing Cobalt Metal Nanoparticle

International Nuclear Information System (INIS)

Kang, Myunggoo; Lee, Dong Heon; Jung, Hyun

2016-01-01

In this study, we attempted to apply Co metal nanoparticles decorated on the surface of the porous graphene (Co-PG) as the electrochemical hydrogen storage system. Co-PG was successfully synthesized by the soft-template method. To determine the synthetic strategy of porous graphene and Co nanoparticles, we compare the obtained Co-PG with two different materials such as Co nanoparticle decorated reduced graphene oxide without soft-template (Co-RGO) and porous graphene without Co nanoparticle (PG). The experimental details regarding the synthesis and characterization of the Co-PG, Co-RGO, and PG samples are provided in Supporting Information. Co-PG with interpenetrating porous networks and immobilized Co metal nanoparticles were successfully synthesized by the soft-template method. The obtained Co-PG exhibited high-surface area with ink-bottle open pores owing to the homogeneous dispersion of P123 micellar rods. The XRD and FE-SEM analyses clearly confirm that Co nanoparticles were immobilized on to the surface of porous graphene without any significant aggregation. The as-obtained Co-PG showed good electrochemical performance such as capacity and cycle stability for hydrogen storage. Based on these results, we believe that the Co-PG with a high-specific surface area could be worthwhile to investigate as not only electrochemical hydrogen storage materials but also other energy storage applications

Enhanced hydrogen reaction kinetics of nanostructured Mg-based composites with nanoparticle metal catalysts dispersed on supports

International Nuclear Information System (INIS)

Yoo, Yeong; Tuck, Mark; Kondakindi, Rajender; Seo, Chan-Yeol; Dehouche, Zahir; Belkacemi, Khaled

2007-01-01

Hydrogen reaction kinetics of nanocrystalline MgH 2 co-catalyzed with Ba 3 (Ca 1+x Nb 2-x )O 9-δ (BCN) proton conductive ceramics and nanoparticle bimetallic catalyst of Ni/Pd dispersed on single wall carbon nanotubes (SWNTs) support has been investigated. The nanoparticle bimetallic catalysts of Ni/Pd supported by SWNTs were synthesized based on a novel polyol method using NiCl 2 .6H 2 O, PdCl 2 , NaOH and ethylene glycol (EG). The nanostructured Mg composites co-catalyzed with BCN and bimetallic supported catalysts exhibited stable hydrogen desorption capacity of 6.3-6.7 wt.% H 2 and the significant enhancement of hydrogen desorption kinetics at 230-300 deg. C in comparison to either non-catalyzed MgH 2 or the nanocomposite of MgH 2 catalyzed with BCN

Reviewing the Tannic Acid Mediated Synthesis of Metal Nanoparticles

Directory of Open Access Journals (Sweden)

Tufail Ahmad

2014-01-01

Full Text Available Metal nanoparticles harbour numerous exceptional physiochemical properties absolutely different from those of bulk metal as a function of their extremely small size and large superficial area to volume. Naked metal nanoparticles are synthesized by various physical and chemical methods. Chemical methods involving metal salt reduction in solution enjoy an extra edge over other protocols owing to their relative facileness and capability of controlling particle size along with the attribute of surface tailoring. Although chemical methods are the easiest, they are marred by the use of hazardous chemicals such as borohydrides. This has led to inclination of scientific community towards eco-friendly agents for the reduction of metal salts to form nanoparticles. Tannic acid, a plant derived polyphenolic compound, is one such agent which embodies characteristics of being harmless and environmentally friendly combined with being a good reducing and stabilizing agent. In this review, first various methods used to prepare metal nanoparticles are highlighted and further tannic acid mediated synthesis of metal nanoparticles is emphasized. This review brings forth the most recent findings on this issue.

Reviewing the Tannic Acid Mediated Synthesis of Metal Nanoparticles

International Nuclear Information System (INIS)

Ahmad, T.

2014-01-01

Metal nanoparticles harbour numerous exceptional physiochemical properties absolutely different from those of bulk metal as a function of their extremely small size and large superficial area to volume. Naked metal nanoparticles are synthesized by various physical and chemical methods. Chemical methods involving metal salt reduction in solution enjoy an extra edge over other protocols owing to their relative facileness and capability of controlling particle size along with the attribute of surface tailoring. Although chemical methods are the easiest, they are marred by the use of hazardous chemicals such as borohydrides. This has led to inclination of scientific community towards eco-friendly agents for the reduction of metal salts to form nanoparticles. Tannic acid, a plant derived polyphenolic compound, is one such agent which embodies characteristics of being harmless and environmentally friendly combined with being a good reducing and stabilizing agent. In this review, first various methods used to prepare metal nanoparticles are highlighted and further tannic acid mediated synthesis of metal nanoparticles is emphasized. This review brings forth the most recent findings on this issue.

Thin films of metal-organic compounds and metal nanoparticle

Indian Academy of Sciences (India)

Thin films of metal-organic compounds and metal nanoparticle-embedded polymers for nonlinear optical applications. S Philip Anthony Shatabdi Porel D ... Thin films based on two very different metal-organic systems are developed and some nonlinear optical applications are explored. A family of zinc complexes which ...

Characterization of size, surface charge, and agglomeration state of nanoparticle dispersions for toxicological studies

International Nuclear Information System (INIS)

Jiang Jingkun; Oberdoerster, Guenter; Biswas, Pratim

2009-01-01

Characterizing the state of nanoparticles (such as size, surface charge, and degree of agglomeration) in aqueous suspensions and understanding the parameters that affect this state are imperative for toxicity investigations. In this study, the role of important factors such as solution ionic strength, pH, and particle surface chemistry that control nanoparticle dispersion was examined. The size and zeta potential of four TiO 2 and three quantum dot samples dispersed in different solutions (including one physiological medium) were characterized. For 15 nm TiO 2 dispersions, the increase of ionic strength from 0.001 M to 0.1 M led to a 50-fold increase in the hydrodynamic diameter, and the variation of pH resulted in significant change of particle surface charge and the hydrodynamic size. It was shown that both adsorbing multiply charged ions (e.g., pyrophosphate ions) onto the TiO 2 nanoparticle surface and coating quantum dot nanocrystals with polymers (e.g., polyethylene glycol) suppressed agglomeration and stabilized the dispersions. DLVO theory was used to qualitatively understand nanoparticle dispersion stability. A methodology using different ultrasonication techniques (bath and probe) was developed to distinguish agglomerates from aggregates (strong bonds), and to estimate the extent of particle agglomeration. Probe ultrasonication performed better than bath ultrasonication in dispersing TiO 2 agglomerates when the stabilizing agent sodium pyrophosphate was used. Commercially available Degussa P25 and in-house synthesized TiO 2 nanoparticles were used to demonstrate identification of aggregated and agglomerated samples.

Metal nanoparticles/ionic liquid/cellulose: polymeric membrane for hydrogenation reactions

Directory of Open Access Journals (Sweden)

Marcos Alexandre Gelesky

2014-01-01

Full Text Available Rhodium and platinum nanoparticles were supported in polymeric membranes with 10, 20 and 40 µm thickness. The polymeric membranes were prepared combining cellulose acetate and the ionic liquid (IL 1-n-butyl-3-methylimidazolium bis(trifluoromethane sulfonylimide (BMI.(NTf2. The presence of metal nanoparticles induced an increase in the polymeric membrane surface areas. The increase of the IL content resulted in an improvement of elasticity and decrease in tenacity and toughness, whereas the stress at break was not affected. The presence of IL probably causes an increase in the separation between the cellulose molecules that result in a higher flexibility and processability of the polymeric membrane. The CA/IL/M(0 combinations exhibit an excellent synergistic effect that enhances the activity and durability of the catalyst for the hydrogenation of cyclohexene. The CA/IL/M(0 polymeric membrane displays higher catalytic activity (up to 7.353 h-1 for the 20 mm of CA/IL/Pt(0 and stability than the nanoparticles dispersed only in the IL.

Aggregation and adhesion of gold nanoparticles in phosphate buffered saline

Energy Technology Data Exchange (ETDEWEB)

Du Shangfeng, E-mail: s.du@bham.ac.uk; Kendall, Kevin; Toloueinia, Panteha; Mehrabadi, Yasamin; Gupta, Gaurav; Newton, Jill [University of Birmingham, School of Chemical Engineering (United Kingdom)

2012-03-15

In applications in medicine and more specifically drug delivery, the dispersion stability of nanoparticles plays a significant role on their final performances. In this study, with the use of two laser technologies, dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA), we report a simple method to estimate the stability of nanoparticles dispersed in phosphate buffered saline (PBS). Stability has two features: (1) self-aggregation as the particles tend to stick to each other; (2) disappearance of particles as they adhere to surrounding substrate surfaces such as glass, metal, or polymer. By investigating the effects of sonication treatment and surface modification by five types of surfactants, including nonylphenol ethoxylate (NP9), polyvinyl pyrrolidone (PVP), human serum albumin (HSA), sodium dodecyl sulfate (SDS) and citrate ions on the dispersion stability, the varying self-aggregation and adhesion of gold nanoparticles dispersed in PBS are demonstrated. The results showed that PVP effectively prevented aggregation, while HSA exhibited the best performance in avoiding the adhesion of gold nanoparticle in PBS onto glass and metal. The simple principle of this method makes it a high potential to be applied to other nanoparticles, including virus particles, used in dispersing and processing.

Mangifera Indica leaf-assisted biosynthesis of well-dispersed silver nanoparticles

Science.gov (United States)

Philip, Daizy

2011-01-01

The use of various parts of plants for the synthesis of nanoparticles is considered as a green technology as it does not involve any harmful chemicals. The present study reports a facile and rapid biosynthesis of well-dispersed silver nanoparticles. The method developed is environmentally friendly and allows the reduction to be accelerated by changing the temperature and pH of the reaction mixture consisting of aqueous AgNO 3 and Mangifera Indica leaf extract. At a pH of 8, the colloid consists of well-dispersed triangular, hexagonal and nearly spherical nanoparticles having size ˜20 nm. The UV-vis spectrum of silver nanoparticles gave surface plasmon resonance (SPR) at 439 nm. The synthesized nanocrystals were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Water soluble organics present in the leaf are responsible for the reduction of silver ions. This green method provides faster synthesis comparable to chemical methods and can be used in areas such as cosmetics, foods and medical applications.

Optical study of the ultrasonic formation process of noble metal nanoparticles dispersed inside the pores of monolithic mesoporous silica

CERN Document Server

Fu Gan Hua; Kan Cai Xia; Li Cun Cheng; Fang Qi

2003-01-01

Gold nanoparticles dispersed inside the pores of monolithic mesoporous silica were prepared by soaking the silica in a gold (III) ion solution and subsequent ultrasound irradiation. The formation process of gold nanoparticles in the pores of mesoporous silica was investigated based on optical measurements of wrapped and naked soaked silica after ultrasonic irradiation, and the reduction rate effect in solution and pre-soaking effect. It has been shown that acoustic cavitation cannot occur in nano-sized pores. The gold nanoparticles in silica are not formed in situ within the pores but produced mainly by diffusion of the gold clusters formed in the solution during irradiation into the pores. The radicals formed in solution are exhausted before entering the pores of silica. There exists a critical reduction rate in solution, at which the yield of gold nanoparticles in silica reaches a maximum, and above which there is a decrease in the yield. This is attributed to too quick a growth or aggregation of gold clust...

Simulation of heating by optical absorption in nanoparticle dispersions (Conference Presentation)

Science.gov (United States)

Olbricht, Benjamin C.

2017-02-01

With the proliferation of highly confined, nanophotonic waveguides and laser sources with increasing intensity, the effects of laser heating will begin to greatly impact the materials used in optical applications. In order to better understand the mechanism of laser heating, its timescales, and the dispersion of heat into the material, simulations of nanoparticles in various media are presented. A generic model to describe a variety of nanoparticle shapes and sizes is desirable to describe complex phenomenon. These particles are dispersed into various solids, liquids, or gases depending on the application. To simulate nanoparticles and their interaction with their host material, the Finite Element Method (FEM) is used. Heat transfer following an absorption event is also described by a parabolic partial differential equation, and transient solutions are generated in response to continuous, pulsed, or modulated laser radiation. The simplest physical system described by FEM is that of a broadly-absorbing round-shaped nanoparticle dispersed in viscous host fluid or solid. Many experimental and theoretical studies conveniently describe a very similar system: a carbon "black" nanoparticle suspended in water. This material is well-known to exhibit nonlinear behavior when a laser pulse carrying 0.7 J/cm2 is incident on the material. For this process the FEM simulations agree with experimental results to show that a pulse of this fluence is capable of heating the solvent elements adjacent to the nanoparticle to their boiling point. This creates nonlinear scattering which is empirically observed as a nonlinear decrease in the transmitted power at this input fluence.

Thin films of metal-organic compounds and metal nanoparticle ...

Indian Academy of Sciences (India)

Optical limiting capability of the nanoparticle-embedded polymer film is demonstrated. Keywords. Polar crystal; uniaxial orientational order; thin film; second harmonic gen- eration; silver ... able content of metal nanoparticles would be of considerable value from an appli- ... polar chain and perpendicular to it [10].

Absorption properties of metal-semiconductor hybrid nanoparticles.

Science.gov (United States)

Shaviv, Ehud; Schubert, Olaf; Alves-Santos, Marcelo; Goldoni, Guido; Di Felice, Rosa; Vallée, Fabrice; Del Fatti, Natalia; Banin, Uri; Sönnichsen, Carsten

2011-06-28

The optical response of hybrid metal-semiconductor nanoparticles exhibits different behaviors due to the proximity between the disparate materials. For some hybrid systems, such as CdS-Au matchstick-shaped hybrids, the particles essentially retain the optical properties of their original components, with minor changes. Other systems, such as CdSe-Au dumbbell-shaped nanoparticles, exhibit significant change in the optical properties due to strong coupling between the two materials. Here, we study the absorption of these hybrids by comparing experimental results with simulations using the discrete dipole approximation method (DDA) employing dielectric functions of the bare components as inputs. For CdS-Au nanoparticles, the DDA simulation provides insights on the gold tip shape and its interface with the semiconductor, information that is difficult to acquire by experimental means alone. Furthermore, the qualitative agreement between DDA simulations and experimental data for CdS-Au implies that most effects influencing the absorption of this hybrid system are well described by local dielectric functions obtained separately for bare gold and CdS nanoparticles. For dumbbell shaped CdSe-Au, we find a shortcoming of the electrodynamic model, as it does not predict the "washing out" of the optical features of the semiconductor and the metal observed experimentally. The difference between experiment and theory is ascribed to strong interaction of the metal and semiconductor excitations, which spectrally overlap in the CdSe case. The present study exemplifies the employment of theoretical approaches used to describe the optical properties of semiconductors and metal nanoparticles, to achieve better understanding of the behavior of metal-semiconductor hybrid nanoparticles.

Enhanced Radiofrequency Ablation With Magnetically Directed Metallic Nanoparticles.

Science.gov (United States)

Nguyen, Duy T; Tzou, Wendy S; Zheng, Lijun; Barham, Waseem; Schuller, Joseph L; Shillinglaw, Benjamin; Quaife, Robert A; Sauer, William H

2016-05-01

Remote heating of metal located near a radiofrequency ablation source has been previously demonstrated. Therefore, ablation of cardiac tissue treated with metallic nanoparticles may improve local radiofrequency heating and lead to larger ablation lesions. We sought to evaluate the effect of magnetic nanoparticles on tissue sensitivity to radiofrequency energy. Ablation was performed using an ablation catheter positioned with 10 g of force over prepared ex vivo specimens. Tissue temperatures were measured and lesion volumes were acquired. An in vivo porcine thigh model was used to study systemically delivered magnetically guided iron oxide (FeO) nanoparticles during radiofrequency application. Magnetic resonance imaging and histological staining of ablated tissue were subsequently performed as a part of ablation lesion analysis. Ablation of ex vivo myocardial tissue treated with metallic nanoparticles resulted in significantly larger lesions with greater impedance changes and evidence of increased thermal conductivity within the tissue. Magnet-guided localization of FeO nanoparticles within porcine thigh preps was demonstrated by magnetic resonance imaging and iron staining. Irrigated ablation in the regions with greater FeO, after FeO infusion and magnetic guidance, created larger lesions without a greater incidence of steam pops. Metal nanoparticle infiltration resulted in significantly larger ablation lesions with altered electric and thermal conductivity. In vivo magnetic guidance of FeO nanoparticles allowed for facilitated radiofrequency ablation without direct infiltration into the targeted tissue. Further research is needed to assess the clinical applicability of this ablation strategy using metallic nanoparticles for the treatment of cardiac arrhythmias. © 2016 American Heart Association, Inc.

High-performance 3D printing of hydrogels by water-dispersible photoinitiator nanoparticles.

Science.gov (United States)

Pawar, Amol A; Saada, Gabriel; Cooperstein, Ido; Larush, Liraz; Jackman, Joshua A; Tabaei, Seyed R; Cho, Nam-Joon; Magdassi, Shlomo

2016-04-01

In the absence of water-soluble photoinitiators with high absorbance in the ultraviolet (UV)-visible range, rapid three-dimensional (3D) printing of hydrogels for tissue engineering is challenging. A new approach enabling rapid 3D printing of hydrogels in aqueous solutions is presented on the basis of UV-curable inks containing nanoparticles of highly efficient but water-insoluble photoinitiators. The extinction coefficient of the new water-dispersible nanoparticles of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) is more than 300 times larger than the best and most used commercially available water-soluble photoinitiator. The TPO nanoparticles absorb significantly in the range from 385 to 420 nm, making them suitable for use in commercially available, low-cost, light-emitting diode-based 3D printers using digital light processing. The polymerization rate at this range is very fast and enables 3D printing that otherwise is impossible to perform without adding solvents. The TPO nanoparticles were prepared by rapid conversion of volatile microemulsions into water-dispersible powder, a process that can be used for a variety of photoinitiators. Such water-dispersible photoinitiator nanoparticles open many opportunities to enable rapid 3D printing of structures prepared in aqueous solutions while bringing environmental advantages by using low-energy curing systems and avoiding the need for solvents.

Transition Metal Dopants Essential for Producing Ferromagnetism in Metal Oxide Nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Johnson, Lydia; Thurber, Aaron P.; Anghel, Josh; Sabetian, Maryam; Engelhard, Mark H.; Tenne, D.; Hanna, Charles; Punnoose, Alex

2010-08-13

Recent claims that ferromagnetism can be produced in nanoparticles of metal oxides without the presence of transition metal dopants has been refuted in this work by investigating 62 high quality well-characterized nanoparticle samples of both undoped and Fe doped (0-10% Fe) ZnO. The undoped ZnO nanoparticles showed zero or negligible magnetization, without any dependence on the nanoparticle size. However, chemically synthesized Zn₁₋xFexO nanoparticles showed clear ferromagnetism, varying systematically with Fe concentration. Furthermore, the magnetic properties of Zn₁₋xFexO nanoparticles showed strong dependence on the reaction media used to prepare the samples. The zeta potentials of the Zn₁₋xFexO nanoparticles prepared using different reaction media were significantly different, indicating strong differences in the surface structure. Electron paramagnetic resonance studies clearly showed that the difference in the ferromagnetic properties of Zn₁₋xFexO nanoparticles with different surface structures originate from differences in the fraction of the doped Fe³⁺ ions that are coupled ferromagnetically.

Water dispersal and functionalization of hydrophobic Iron oxide nanoparticles with lipid-modified poly(amidoamine) dendrimers

NARCIS (Netherlands)

Boni, A; Albertazzi, L.; Innocenti, C; Gemmi, M; Bifone, A

2013-01-01

A novel and facile method for water dispersal of hydrophobic iron oxide nanoparticles based on the amphiphilic PAMAM-C-12 dendrimer is described. Stable and highly concentrated water dispersions of multifunctional, magnetic nanoparticles were obtained with this single-step approach, and showed

Synthesis of bi-phase dispersible core-shell FeAu@ZnO magneto-opto-fluorescent nanoparticles

Science.gov (United States)

Li, Xue-Mei; Liu, Hong-Ling; Liu, Xiao; Fang, Ning; Wang, Xian-Hong; Wu, Jun-Hua

2015-11-01

Bi-phase dispersible core-shell FeAu@ZnO magneto-opto-fluorescent nanoparticles were synthesized by a modified nanoemulsion process using poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO) as the surfactant. The morphology and crystal structure of the nanoparticles were studied by TEM/HRTEM and XRD. The nanoparticles manifest soft ferromagnetic and/or near superparamagnetic behavior with a small coercivity of ~19 Oe at room temperature. The corresponding magnetic hysteresis curves were elucidated by the modified Langevin equation. The FTIR study confirms the PEO-PPO-PEO molecules on the surface of the nanoparticles. The UV-vis and PL results reveal the well-behaved absorption bands including surface plasmon resonance and multiple visible fingerprint photoluminescent emissions of the nanoparticles dispersed in both hydrophilic and hydrophobic solvents. Moreover, the processes of solvent dispersion-collection of the nanoparticles were demonstrated for application readiness of such core-shell nanostructures.

Large patternable metal nanoparticle sheets by photo/e-beam lithography

Science.gov (United States)

Saito, Noboru; Wang, Pangpang; Okamoto, Koichi; Ryuzaki, Sou; Tamada, Kaoru

2017-10-01

Techniques for micro/nano-scale patterning of large metal nanoparticle sheets can potentially be used to realize high-performance photoelectronic devices because the sheets provide greatly enhanced electrical fields around the nanoparticles due to localized surface plasmon resonances. However, no single metal nanoparticle sheet currently exists with sufficient durability for conventional lithographical processes. Here, we report large photo and/or e-beam lithographic patternable metal nanoparticle sheets with improved durability by incorporating molecular cross-linked structures between nanoparticles. The cross-linked structures were easily formed by a one-step chemical reaction; immersing a single nanoparticle sheet consisting of core metals, to which capping molecules ionically bond, in a dithiol ethanol solution. The ligand exchange reaction processes were discussed in detail, and we demonstrated 20 μm wide line and space patterns, and a 170 nm wide line of the silver nanoparticle sheets.

Platinum-TM (TM = Fe, Co) alloy nanoparticles dispersed nitrogen doped (reduced graphene oxide-multiwalled carbon nanotube) hybrid structure cathode electrocatalysts for high performance PEMFC applications.

Science.gov (United States)

Vinayan, B P; Ramaprabhu, S

2013-06-07

The efforts to push proton exchange membrane fuel cells (PEMFC) for commercial applications are being undertaken globally. In PEMFC, the sluggish kinetics of oxygen reduction reactions (ORR) at the cathode can be improved by the alloying of platinum with 3d-transition metals (TM = Fe, Co, etc.) and with nitrogen doping, and in the present work we have combined both of these aspects. We describe a facile method for the synthesis of a nitrogen doped (reduced graphene oxide (rGO)-multiwalled carbon nanotubes (MWNTs)) hybrid structure (N-(G-MWNTs)) by the uniform coating of a nitrogen containing polymer over the surface of the hybrid structure (positively surface charged rGO-negatively surface charged MWNTs) followed by the pyrolysis of these (rGO-MWNTs) hybrid structure-polymer composites. The N-(G-MWNTs) hybrid structure is used as a catalyst support for the dispersion of platinum (Pt), platinum-iron (Pt3Fe) and platinum-cobalt (Pt3Co) alloy nanoparticles. The PEMFC performances of Pt-TM alloy nanoparticle dispersed N-(G-MWNTs) hybrid structure electrocatalysts are 5.0 times higher than that of commercial Pt-C electrocatalysts along with very good stability under acidic environment conditions. This work demonstrates a considerable improvement in performance compared to existing cathode electrocatalysts being used in PEMFC and can be extended to the synthesis of metal, metal oxides or metal alloy nanoparticle decorated nitrogen doped carbon nanostructures for various electrochemical energy applications.

An overview of experimental results and dispersion modelling of nanoparticles in the wake of moving vehicles

International Nuclear Information System (INIS)

Carpentieri, Matteo; Kumar, Prashant; Robins, Alan

2011-01-01

Understanding the transformation of nanoparticles emitted from vehicles is essential for developing appropriate methods for treating fine scale particle dynamics in dispersion models. This article provides an overview of significant research work relevant to modelling the dispersion of pollutants, especially nanoparticles, in the wake of vehicles. Literature on vehicle wakes and nanoparticle dispersion is reviewed, taking into account field measurements, wind tunnel experiments and mathematical approaches. Field measurements and modelling studies highlighted the very short time scales associated with nanoparticle transformations in the first stages after the emission. These transformations strongly interact with the flow and turbulence fields immediately behind the vehicle, hence the need of characterising in detail the mixing processes in the vehicle wake. Very few studies have analysed this interaction and more research is needed to build a basis for model development. A possible approach is proposed and areas of further investigation identified. - Research highlights: → Nanoparticle emissions experience very short transformation time scales. → Vehicle wakes need to be characterised to analyse nanoparticle dispersion. → Fast response measurements of nanoparticle evolution in vehicle wakes are very rare. → Wind tunnel methodologies can be further improved to include nanoparticle dynamics. → A simple mathematical approach has been proposed for future development. - The transformation of nanoparticles and the flow characteristics in both the near and far wake regions must be understood in order to develop mathematical models.

Enhancement of ethanol oxidation at Pt and PtRu nanoparticles dispersed over hybrid zirconia-rhodium supports

Science.gov (United States)

Rutkowska, Iwona A.; Koster, Margaretta D.; Blanchard, Gary J.; Kulesza, Pawel J.

2014-12-01

A catalytic material for electrooxidation of ethanol that utilizes PtRu nanoparticles dispersed over thin films of rhodium-free and rhodium-containing zirconia (ZrO2) supports is described here. The enhancement of electrocatalytic activity (particularly in the potential range as low as 0.25-0.5 V vs. RHE), that has been achieved by dispersing PtRu nanoparticles (loading, 100 μg cm-2) over the hybrid Rh-ZrO2 support composed of nanostructured zirconia and metallic rhodium particles, is clearly evident from comparison of the respective voltammetric and chronoamperometric current densities recorded at room temperature (22 °C) in 0.5 mol dm-3 H2SO4 containing 0.5 mol dm-3 ethanol. Porous ZrO2 nanostructures, that provide a large population of hydroxyl groups in acidic medium in the vicinity of PtRu sites, are expected to facilitate the ruthenium-induced removal of passivating CO adsorbates from platinum, as is apparent from the diagnostic experiments with a small organic molecule such as methanol. Although Rh itself does not show directly any activity toward ethanol oxidation, the metal is expected to facilitate C-C bond splitting in C2H5OH. It has also been found during parallel voltammetric and chronoamperometric measurements that the hybrid Rh-ZrO2 support increases activity of the platinum component itself toward ethanol oxidation in the low potential range.

Synthesis and Bactericidal Properties of Hyaluronic Acid Doped with Metal Nanoparticles

Directory of Open Access Journals (Sweden)

Galo Cárdenas-Triviño

2017-01-01

Full Text Available A study on the nanoparticles size and the antibacterial properties of hyaluronic acid (HA doped with nanoparticles is reported. Nanoparticles from gold, silver, copper, and silver palladium with HA support were performed. The solvated metal atom dispersion (SMAD method with 2-propanol and HA was used. High-resolution transmission electron microscopy (HRTEM, infrared spectroscopy (FT-IR, and thermogravimetric analysis (TGA were conducted. The average sizes of nanoclusters were as follows: HA-Au = 17.88 nm; HA-Ag = 50.41 nm; HA-Cu = 13.33 nm; and HA-AgPd = 33.22 nm. The antibacterial activity of solutions and films containing nanoparticles against American Type Culture Collection (ATCC bacterial strains Escherichia coli (EC, Staphylococcus aureus (SA, Staphylococcus epidermidis (SE, and Pseudomonas aeruginosa (PA was determined. Inhibition was observed for HA-Ag, HA-Cu, and HA-AgPd. Toxicological tests were performed in rats that were injected intraperitoneally with two concentrations of gold, copper, silver, and silver-palladium nanoparticles. No alterations in hepatic parameters, including ALT (alanine aminotransferase, GGT (gamma-glutamyl transpeptidase bilirubin, and albumin, were observed after 14 days. These films could be used as promoters of skin recovery and Grades I and II cutaneous burns and as scaffolds.

Nanoparticles dispersion in processing functionalised PP/TiO2 nanocomposites: distribution and properties

International Nuclear Information System (INIS)

El-Dessouky, Hassan M.; Lawrence, Carl A.

2011-01-01

Future innovations in textiles and fibrous materials are likely to demand fibres with enhanced multifunctionality. The fibres can be functionalized by dispersing nanoadditives into the polymer during melt compounding/spinning. TiO 2 nanoparticles have the potential to improve UV resistance, antistatic, as well as impart self-cleaning by photocatalysis and thereby de-odour and antimicrobial effects. In this study, a micro-lab twin-screw extruder was used to produce samples of polypropylene (PP) nanocomposite monofilaments, doped with nano titanium oxide (TiO 2 )/manganese oxide (MnO) compound having size ranging from 60 to 200 nm. As a control sample, PP filaments without additives were also extruded. Three samples were produced containing different concentrations (wt%) of the TiO 2 compound, i.e. 0.95, 1.24 and 1.79%. Nano metal-oxide distribution in the as-spun and drawn nanocomposite filaments was analysed. Although, there are small clusters of the nanoparticles, the characterizing techniques showed good dispersion and distribution of the modified TiO 2 along and across the processed filaments. From UV spectroscopy and TGA, a significant enhancement of polypropylene UV protection and thermal stability were observed: PP with higher percentage of TiO 2 absorbed UV wavelength of 387 nm and thermally decomposed at 320.16 °C accompanied by 95% weight loss.

Electrospun Polyaniline-Based Composite Nanofibers: Tuning the Electrical Conductivity by Tailoring the Structure of Thiol-Protected Metal Nanoparticles

Directory of Open Access Journals (Sweden)

Filippo Pierini

2017-01-01

Full Text Available Composite nanofibers made of a polyaniline-based polymer blend and different thiol-capped metal nanoparticles were prepared using ex situ synthesis and electrospinning technique. The effects of the nanoparticle composition and chemical structure on the electrical properties of the nanocomposites were investigated. This study confirmed that Brust’s procedure is an effective method for the synthesis of sub-10 nm silver, gold, and silver-gold alloy nanoparticles protected with different types of thiols. Electron microscopy results demonstrated that electrospinning is a valuable technique for the production of composite nanofibers with similar morphology and revealed that nanofillers are well-dispersed into the polymer matrix. X-ray diffraction tests proved the lack of a significant influence of the nanoparticle chemical structure on the polyaniline chain arrangement. However, the introduction of conductive nanofillers in the polymer matrix influences the charge transport noticeably improving electrical conductivity. The enhancement of electrical properties is mediated by the nanoparticle capping layer structure. The metal nanoparticle core composition is a key parameter, which exerted a significant influence on the conductivity of the nanocomposites. These results prove that the proposed method can be used to tune the electrical properties of nanocomposites.

Shellac/nanoparticles dispersions as protective materials for wood

Science.gov (United States)

Weththimuni, Maduka L.; Capsoni, Doretta; Malagodi, Marco; Milanese, Chiara; Licchelli, Maurizio

2016-12-01

Wood is a natural material that finds numerous and widespread applications, but is subject to different decay processes. Surface coating is the most common method used to protect wood against deterioration and to improve and stabilize its distinctive appearance. Shellac is a natural resin that has been widely used as a protective material for wooden artefacts (e.g. furniture, musical instruments), due to its excellent properties. Nevertheless, diffusion of shellac-based varnishes has significantly declined during the last decades, because of some limitations such as the softness of the coating, photo-degradation, and sensitivity to alcoholic solvents and to pH variations. In the present study, different inorganic nanoparticles were dispersed into dewaxed natural shellac and the resulting materials were investigated even after application on wood specimens in order to assess variations of the coating properties. Analyses performed by a variety of experimental techniques have shown that dispersed nanoparticles do not significantly affect some distinctive and desirable features of the shellac varnish such as chromatic aspect, film-forming ability, water repellence, and adhesion. On the other hand, the obtained results suggested that some weak points of the coating, such as low hardness and poor resistance to UV-induced ageing, can be improved by adding ZrO2 and ZnO nanoparticles, respectively.

Noble Metal Nanoparticles for Biosensing Applications

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Pedro V. Baptista

2012-02-01

Full Text Available In the last decade the use of nanomaterials has been having a great impact in biosensing. In particular, the unique properties of noble metal nanoparticles have allowed for the development of new biosensing platforms with enhanced capabilities in the specific detection of bioanalytes. Noble metal nanoparticles show unique physicochemical properties (such as ease of functionalization via simple chemistry and high surface-to-volume ratios that allied with their unique spectral and optical properties have prompted the development of a plethora of biosensing platforms. Additionally, they also provide an additional or enhanced layer of application for commonly used techniques, such as fluorescence, infrared and Raman spectroscopy. Herein we review the use of noble metal nanoparticles for biosensing strategies—from synthesis and functionalization to integration in molecular diagnostics platforms, with special focus on those that have made their way into the diagnostics laboratory.

Multifunctional metal ferrite nanoparticles for MR imaging applications

International Nuclear Information System (INIS)

Joshi, Hrushikesh M.

2013-01-01

Magnetic Resonance Imaging (MRI) is a very powerful non-invasive tool for in vivo imaging and clinical diagnosis. With rapid advancement in nanoscience and nanotechnology, there is rapid growth in nanoparticles-based contrast agents. Progress in synthetic protocols enable synthesis of multifunctional nanoparticles which facilitated efforts toward the development of multimodal contrast agents. In this review, recent developments in metal ferrite-based MR contrast agents have been described. Specifically, effect of size, shape, composition, assembly and surface modification of metal ferrite nanoparticles on their T 2 contrast have been discussed. The review further outlines the effect of leaching on MRI contrast and other various factors which affect the multimodal ability of the (T 1 –T 2 and T 2 -thermal activation) metal ferrite nanoparticles.

Facile synthesis of dispersed Ag nanoparticles on chitosan-TiO2 composites as recyclable nanocatalysts for 4-nitrophenol reduction

Science.gov (United States)

Xiao, Gang; Zhao, Yilin; Li, Linghui; Pratt, Jonathan O.; Su, Haijia; Tan, Tianwei

2018-04-01

This paper presents a facile, rapid, and controllable procedure for the recovery of trace Ag+ ions and in situ assembly of well dispersed Ag nanoparticles on chitosan-TiO2 composites through bioaffinity adsorption followed by photocatalytic reduction. The prepared Ag nanoparticles are proven to be efficient and recyclable nanocatalysts for the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4. Well dispersed quasi-spherical Ag NPs are synthesized in 20 min in the designed inner-irradiated photocatalytic system under a wide range of Ag+ concentrations (50-200 mg l-1), temperatures (10 °C-25 °C) conditions, and UV or visible light irradiation. The synthesized Ag NPs can catalyze the reduction of 4-nitrophenol by NaBH4 at 100% conversion in 120 min and preserve the catalytic activity in five successive cycles. This procedure for trace Ag+ ions recovery and Ag NPs assembly has the potential to be scaled up for the mass production of recyclable Ag nanocatalysts. The present work provides a green and efficient procedure for the conversion of hazardous 4-nitrophenol to industrially important 4-aminophenol and also sheds a light on designing scaled-up procedures for treating high volumes of wastewater with dilute heavy metals to produce recyclable metallic nanocatalysts in aqueous systems.

Microemulsion Synthesis of Nanoparticles

Directory of Open Access Journals (Sweden)

Gotić, M.

2013-11-01

Full Text Available Nanoparticles and nanomaterials have wide applications in electronics, physics, material design, being also utilized as sensors, catalysts, and more and more in biomedicine. Microemulsions are an exceptionally suitable medium for the synthesis of nanoparticles due to their thermodynamical stability, great solubility of both polar and nonpolar components, as well as their ability to control the size, dispersity and shape of the particles. This review presents microemulsion techniques for the synthesis of inorganic nanoparticles. It takes place in water-in-oil microemulsions by mixing one microemulsion with a cationic precursor, and the other with a precipitating or reducing agent, or by direct addition of reducing agents or gas (O2, NH3 ili CO2 into microemul sion (Fig. 1. Metal nanoparticles are used as catalysts, sensors, ferrofluids etc. They are produced by reducing the metal cation with a suitable reducing agent. In a similar way, one can prepare nanoparticles of alloys from the metal salts, provided that the metals are mutually soluble. The microemulsion technique is also suitable for depositing nanoparticles onto various surfaces. Highly active catalysts made from nanoparticles of Pt, Pd, Rh and other noble metals may be obtained in this way. Metal oxides and hydroxides may be prepared by hydrolysis or precipitation in the water core of microemulsion. Precipitation can be initiated by adding the base or precipitating agent into the microemulsion with water solution of metal ions. Similarly, nanoparticles may be prepared of sulphides, halogenides, cyanides, carbonates, sulphates and other insoluble metal salts. To prevent oxidation of nanoparticles, especially Fe, the particles are coated with inert metals, oxides, various polymers etc. Coating may provide additional functionality; e.g. coating with gold allows subsequent functionalization with organic compounds containing sulphur, due to the strong Au–S bond. Polymer coatings decrease

Surface modification by metal ion implantation forming metallic nanoparticles in an insulating matrix

International Nuclear Information System (INIS)

Salvadori, M.C.; Teixeira, F.S.; Sgubin, L.G.; Cattani, M.; Brown, I.G.

2014-01-01

Highlights: • Metal nanoparticles can be produced through metallic ion implantation in insulating substrate, where the implanted metal self-assembles into nanoparticles. • The nanoparticles nucleate near the maximum of the implantation depth profile, that can be estimated by computer simulation using the TRIDYN. • Nanocomposites, obtained by this way, can be produced in different insulator materials. More specifically we have studied Au/PMMA (polymethylmethacrylate), Pt/PMMA, Ti/alumina and Au/alumina systems. • The nanocomposites were characterized by measuring the resistivity of the composite layer as function of the dose implanted, reaching the percolation threshold. • Excellent agreement was found between the experimental results and the predictions of the theory. - Abstract: There is special interest in the incorporation of metallic nanoparticles in a surrounding dielectric matrix for obtaining composites with desirable characteristics such as for surface plasmon resonance, which can be used in photonics and sensing, and controlled surface electrical conductivity. We have investigated nanocomposites produced by metal ion implantation into insulating substrates, where the implanted metal self-assembles into nanoparticles. The nanoparticles nucleate near the maximum of the implantation depth profile (projected range), which can be estimated by computer simulation using the TRIDYN code. TRIDYN is a Monte Carlo simulation program based on the TRIM (Transport and Range of Ions in Matter) code that takes into account compositional changes in the substrate due to two factors: previously implanted dopant atoms, and sputtering of the substrate surface. Our study show that the nanoparticles form a bidimentional array buried a few nanometers below the substrate surface. We have studied Au/PMMA (polymethylmethacrylate), Pt/PMMA, Ti/alumina and Au/alumina systems. Transmission electron microscopy of the implanted samples show that metallic nanoparticles form in

Magnetorheology of colloidal dispersion containing Fe nanoparticles synthesized by the arc-plasma method

International Nuclear Information System (INIS)

Noma, Junichi; Abe, Hiroya; Kikuchi, Takehito; Furusho, Junji; Naito, Makio

2010-01-01

Spherical crystalline Fe nanoparticles, ∼100 nm in diameter, were synthesized under Ar-50% H 2 arc-plasma. These nanoparticles were dispersed in silicone oil after silane treatment on as-grown thin oxide layer (∼2 nm) to make their surfaces hydrophobic. The resulting Fe nanoparticles exhibited a high saturation magnetization of ∼190 emu/g at room temperature. The static magnetorheological behavior was measured for the colloidal dispersion (solid concentration: 15 vol%) at room temperature under magnetic flux densities of 0-0.3 T, using a parallel-plate-type commercial rheometer. The yield stress continuously increased with magnetic flux density, demonstrating the Bingham plastic behavior. Moreover, subjecting the sample to a magnetic flux density of 0.3 T increased the yield stress by ∼10 2 . Additionally, the colloidal dispersion exhibited good stability against sedimentation.

Magnetorheology of colloidal dispersion containing Fe nanoparticles synthesized by the arc-plasma method

Science.gov (United States)

Noma, Junichi; Abe, Hiroya; Kikuchi, Takehito; Furusho, Junji; Naito, Makio

2010-07-01

Spherical crystalline Fe nanoparticles, ˜100 nm in diameter, were synthesized under Ar-50% H 2 arc-plasma. These nanoparticles were dispersed in silicone oil after silane treatment on as-grown thin oxide layer (˜2 nm) to make their surfaces hydrophobic. The resulting Fe nanoparticles exhibited a high saturation magnetization of ˜190 emu/g at room temperature. The static magnetorheological behavior was measured for the colloidal dispersion (solid concentration: 15 vol%) at room temperature under magnetic flux densities of 0-0.3 T, using a parallel-plate-type commercial rheometer. The yield stress continuously increased with magnetic flux density, demonstrating the Bingham plastic behavior. Moreover, subjecting the sample to a magnetic flux density of 0.3 T increased the yield stress by ˜10 2. Additionally, the colloidal dispersion exhibited good stability against sedimentation.

Enhanced bioavailability of sirolimus via preparation of solid dispersion nanoparticles using a supercritical antisolvent process

Directory of Open Access Journals (Sweden)

Kim MS

2011-11-01

Full Text Available Min-Soo Kim1, Jeong-Soo Kim1, Hee Jun Park1, Won Kyung Cho1,3, Kwang-Ho Cha1,3, Sung-Joo Hwang2,31College of Pharmacy, Chungnam National University, Daejeon, Republic of Korea, 2College of Pharmacy, 3Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, Republic of KoreaBackground: The aim of this study was to improve the physicochemical properties and bioavailability of poorly water-soluble sirolimus via preparation of a solid dispersion of nanoparticles using a supercritical antisolvent (SAS process.Methods: First, excipients for enhancing the stability and solubility of sirolimus were screened. Second, using the SAS process, solid dispersions of sirolimus-polyvinylpyrrolidone (PVP K30 nanoparticles were prepared with or without surfactants such as sodium lauryl sulfate (SLS, tocopheryl propylene glycol succinate, Sucroester 15, Gelucire 50/13, and Myrj 52. A mean particle size of approximately 250 nm was obtained for PVP K30-sirolimus nanoparticles. Solid state characterization, kinetic solubility, powder dissolution, stability, and pharmacokinetics were analyzed in rats.Results: X-ray diffraction, differential scanning calorimetry, and high-pressure liquid chromatography indicated that sirolimus existed in an anhydrous amorphous form within a solid dispersion of nanoparticles and that no degradation occurred after SAS processing. The improved supersaturation and dissolution of sirolimus as a solid dispersion of nanoparticles appeared to be well correlated with enhanced bioavailability of oral sirolimus in rats. With oral administration of a solid dispersion of PVP K30-SLS-sirolimus nanoparticles, the peak concentration and AUC0→12h of sirolimus were increased by approximately 18.3-fold and 15.2-fold, respectively.Conclusion: The results of this study suggest that preparation of PVP K30-sirolimus-surfactant nanoparticles using the SAS process may be a promising approach for improving the bioavailability of sirolimus

Atomic layer deposited highly dispersed platinum nanoparticles supported on non-functionalized multiwalled carbon nanotubes for the hydrogenation of xylose to xylitol

Science.gov (United States)

Liang, Xinhua; Jiang, Chengjun

2013-09-01

Highly dispersed platinum nanoparticles were deposited on gram quantities of non-functionalized multiwalled carbon nanotubes (MWCNTs) by atomic layer deposition (ALD) in a fluidized bed reactor at 300 °C. (Methylcyclopentadienyl) trimethylplatinum and oxygen were used as precursors. The results of TEM analysis showed that 1.3 nm Pt nanoparticles were highly dispersed on non-functionalized MWCNTs. The porous structures of MWCNTs did not change with the deposition of Pt nanoparticles. For comparison, the commercial 3 wt% Pt/C catalyst was also characterized. The ALD-prepared Pt/MWCNT was used for the hydrogenation of xylose to xylitol. The ALD-prepared Pt/MWCNT showed the best catalytic performance with 100 % conversion of xylose and 99.3 % selectivity to xylitol, compared to commercially available Pt/C, Ru/C, and Raney Ni catalysts. The stability of ALD produced Pt/MWCNT catalyst was higher than that of the commercial Pt/C, due to the presence of surface defects on the MWCNTs and the strong metal-support interaction for the ALD-prepared Pt/MWCNT catalyst.

Atomic layer deposited highly dispersed platinum nanoparticles supported on non-functionalized multiwalled carbon nanotubes for the hydrogenation of xylose to xylitol

Energy Technology Data Exchange (ETDEWEB)

Liang, Xinhua, E-mail: liangxin@mst.edu [Missouri University of Science and Technology, Department of Chemical and Biochemical Engineering (United States); Jiang, Chengjun [Zhejiang University of Science and Technology, Department of Chemical and Biological Engineering (China)

2013-09-15

Highly dispersed platinum nanoparticles were deposited on gram quantities of non-functionalized multiwalled carbon nanotubes (MWCNTs) by atomic layer deposition (ALD) in a fluidized bed reactor at 300 Degree-Sign C. (Methylcyclopentadienyl) trimethylplatinum and oxygen were used as precursors. The results of TEM analysis showed that {approx}1.3 nm Pt nanoparticles were highly dispersed on non-functionalized MWCNTs. The porous structures of MWCNTs did not change with the deposition of Pt nanoparticles. For comparison, the commercial 3 wt% Pt/C catalyst was also characterized. The ALD-prepared Pt/MWCNT was used for the hydrogenation of xylose to xylitol. The ALD-prepared Pt/MWCNT showed the best catalytic performance with 100 % conversion of xylose and 99.3 % selectivity to xylitol, compared to commercially available Pt/C, Ru/C, and Raney Ni catalysts. The stability of ALD produced Pt/MWCNT catalyst was higher than that of the commercial Pt/C, due to the presence of surface defects on the MWCNTs and the strong metal-support interaction for the ALD-prepared Pt/MWCNT catalyst.

Magneto-optical characterization of colloidal dispersions. Application to nickel nanoparticles.

Science.gov (United States)

Pascu, Oana; Caicedo, José Manuel; Fontcuberta, Josep; Herranz, Gervasi; Roig, Anna

2010-08-03

We report here on a fast magneto-optical characterization method for colloidal liquid dispersions of magnetic nanoparticles. We have applied our methodology to Ni nanoparticles with size equal or below 15 nm synthesized by a ligand stabilized solution-phase synthesis. We have measured the magnetic circular dichroism (MCD) of colloidal dispersions and found that we can probe the intrinsic magnetic properties within a wide concentration range, from 10(-5) up to 10(-2) M, with sensitivity to concentrations below 1 microg/mL of magnetic Ni particles. We found that the measured MCD signal scales up with the concentration thus providing a means of determining the concentration values of highly diluted dispersions. The methodology presented here exhibits large flexibility and versatility and might be suitable to study either fundamental problems related to properties of nanosize particles including surface related effects which are highly relevant for magnetic colloids in biomedical applications or to be applied to in situ testing and integration in production lines.

Synthesis and functionalisation of metal and metal oxide nanoparticles for theranostics

OpenAIRE

Mundell, VJ

2013-01-01

Metal and metal oxide nanoparticles including calcium oxide, gold, and superparamagnetic iron oxide nanoparticles (SPIOs) were synthesised using a range of techniques including reduction, co-precipitation and spinning disc technology. SPIOs were primarily synthesised via a co-precipitation method using iron (II) chloride, iron (III) chloride and ammonia; a spinning disc reactor and gaseous ammonia were trialled successfully for scale up, producing spherical particles of 10-40 nm in diameter a...

Antimicrobial properties of metal and metal-halide nanoparticles and their potential applications

Science.gov (United States)

Torrey, Jason Robert

Heavy metals, including silver and copper, have been known to possess antimicrobial properties against bacterial, fungal, and viral pathogens. Metal nanoparticles (aggregations of metal atoms 1-200 nm in size) have recently become the subject of intensive study for their increased antimicrobial properties. In the current studies, metal and metal-halide nanoparticles were evaluated for their antibacterial efficacy. Silver (Ag), silver bromide (AgBr), silver iodide (AgI), and copper iodide (CuI) nanoparticles significantly reduced bacterial numbers of the Gram-negative Pseudomonas aeruginosa and the Gram-positive Staphylococcus aureus within 24 hours and were more effective against P. aeruginosa. CuI nanoparticles were found to be highly effective, reducing both organisms by >4.43 log 10 within 15 minutes at 60 ppm Cu. CuI nanoparticles formulated with different stabilizers (sodium dodecyl sulfate, SDS; polyvinyl pyrrolidone, PVP) were further tested against representative Gram-positive and Gram-negative bacteria, Mycobacteria, a fungus (Candida albicans ), and a non-enveloped virus (poliovirus). Both nanoparticles caused significant reductions in most of the Gram-negative bacteria within five minutes (>5.09-log10). The Gram-positive bacterial species and C. albicans were more sensitive to the CuI-SDS than the CuI-PVP nanoparticles. In contrast, the acid-fast Mycobacterium smegmatis was more resistant to CuI-SDS than CuI-PVP nanoparticles. Poliovirus was more resistant than the other organisms tested except for Mycobacterium fortuitum, which displayed the greatest resistance to CuI nanoparticles. As an example of a real world antimicrobial application, polymer coatings embedded with various concentrations of CuI nanoparticles were tested for antibacterial efficacy against P. aeruginosa and S. aureus. Polyester-epoxy powder coatings were found to display superior uniformity, stability and antimicrobial properties against both organisms (>4.92 log 10 after six hours at

Carbon nanostructured films modified by metal nanoparticles supported on filtering membranes for electroanalysis.

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Paramo, Erica; Palmero, Susana; Heras, Aranzazu; Colina, Alvaro

2018-02-01

A novel methodology to prepare sensors based on carbon nanostructures electrodes modified by metal nanoparticles is proposed. As a proof of concept, a novel bismuth nanoparticle/carbon nanofiber (Bi-NPs/CNF) electrode and a carbon nanotube (CNT)/gold nanoparticle (Au-NPs) have been developed. Bi-NPs/CNF films were prepared by 1) filtering a dispersion of CNFs on a polytetrafluorethylene (PTFE) filter, and 2) filtering a dispersion of Bi-NPs chemically synthesized through this CNF/PTFE film. Next the electrode is prepared by sticking the Bi-NPs/CNF/PTFE film on a PET substrate. In this work, Bi-NPs/CNF ratio was optimized using a Cd 2+ solution as a probe sample. The Cd anodic stripping peak intensity, registered by differential pulse anodic stripping voltammetry (DPASV), is selected as target signal. The voltammograms registered for Cd stripping with this Bi-NPs/CNF/PTFE electrode showed well-defined and highly reproducible electrochemical. The optimized Bi-NPs/CNF electrode exhibits a Cd 2+ detection limit of 53.57 ppb. To demonstrate the utility and versatility of this methodology, single walled carbon nanotubes (SWCNTs) and gold nanoparticles (Au-NPs) were selected to prepare a completely different electrode. Thus, the new Au-NPs/SWCNT/PTFE electrode was tested with a multiresponse technique. In this case, UV/Vis absorption spectroelectrochemistry experiments were carried out for studying dopamine, demonstrating the good performance of the Au-NPs/SWCNT electrode developed. Copyright © 2017 Elsevier B.V. All rights reserved.

In Situ Synthesis of Metal Nanoparticle Embedded Hybrid Soft Nanomaterials.

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Divya, Kizhmuri P; Miroshnikov, Mikhail; Dutta, Debjit; Vemula, Praveen Kumar; Ajayan, Pulickel M; John, George

2016-09-20

The allure of integrating the tunable properties of soft nanomaterials with the unique optical and electronic properties of metal nanoparticles has led to the development of organic-inorganic hybrid nanomaterials. A promising method for the synthesis of such organic-inorganic hybrid nanomaterials is afforded by the in situ generation of metal nanoparticles within a host organic template. Due to their tunable surface morphology and porosity, soft organic materials such as gels, liquid crystals, and polymers that are derived from various synthetic or natural compounds can act as templates for the synthesis of metal nanoparticles of different shapes and sizes. This method provides stabilization to the metal nanoparticles by the organic soft material and advantageously precludes the use of external reducing or capping agents in many instances. In this Account, we exemplify the green chemistry approach for synthesizing these materials, both in the choice of gelators as soft material frameworks and in the reduction mechanisms that generate the metal nanoparticles. Established herein is the core design principle centered on conceiving multifaceted amphiphilic soft materials that possess the ability to self-assemble and reduce metal ions into nanoparticles. Furthermore, these soft materials stabilize the in situ generated metal nanoparticles and retain their self-assembly ability to generate metal nanoparticle embedded homogeneous organic-inorganic hybrid materials. We discuss a remarkable example of vegetable-based drying oils as host templates for metal ions, resulting in the synthesis of novel hybrid nanomaterials. The synthesis of metal nanoparticles via polymers and self-assembled materials fabricated via cardanol (a bioorganic monomer derived from cashew nut shell liquid) are also explored in this Account. The organic-inorganic hybrid structures were characterized by several techniques such as UV-visible spectroscopy, scanning electron microscopy (SEM), and

Electromagnetic Field Redistribution in Metal Nanoparticle on Graphene.

Science.gov (United States)

Li, Keke; Liu, Anping; Wei, Dapeng; Yu, Keke; Sun, Xiaonan; Yan, Sheng; Huang, Yingzhou

2018-04-25

Benefiting from the induced image charge on metal film, the light energy is confined on a film surface under metal nanoparticle dimer, which is called electromagnetic field redistribution. In this work, electromagnetic field distribution of metal nanoparticle monomer or dimer on graphene is investigated through finite-difference time-domain method. The results point out that the electromagnetic field (EM) redistribution occurs in this nanoparticle/graphene hybrid system at infrared region where light energy could also be confined on a monolayer graphene surface. Surface charge distribution was analyzed using finite element analysis, and surface-enhanced Raman spectrum (SERS) was utilized to verify this phenomenon. Furthermore, the data about dielectric nanoparticle on monolayer graphene demonstrate this EM redistribution is attributed to strong coupling between light-excited surface charge on monolayer graphene and graphene plasmon-induced image charge on dielectric nanoparticle surface. Our work extends the knowledge of monolayer graphene plasmon, which has a wide range of applications in monolayer graphene-related film.

Future prospects of antibacterial metal nanoparticles as enzyme inhibitor

International Nuclear Information System (INIS)

Ahmed, Khan Behlol Ayaz; Raman, Thiagarajan; Veerappan, Anbazhagan

2016-01-01

Nanoparticles are being widely used as antibacterial agents with metal nanoparticles emerging as the most efficient antibacterial agents. There have been many studies which have reported the mechanism of antibacterial activity of nanoparticles on bacteria. In this review we aim to emphasize on all the possible mechanisms which are involved in the antibacterial activity of nanoparticles and also to understand their mode of action and role as bacterial enzyme inhibitor by comparing their antibacterial mechanism to that of antibiotics with enzyme inhibition as a major mechanism. With the emergence of widespread antibiotic resistance, nanoparticles offer a better alternative to our conventional arsenal of antibiotics. Once the biological safety of these nanoparticles is addressed, these nanoparticles can be of great medical importance in our fight against bacterial infections. - Highlights: • Mechanisms of antibiotics and metal nanoparticles resemble one another. • Bactericidal mechanisms of NPs are cell wall damage, and ROS generation. • Metal NPs inhibit membrane synthesis enzyme. • NPs can be used as antibacterial agents. • NP as antibacterial strategy important due to widespread antibiotic resistance

Future prospects of antibacterial metal nanoparticles as enzyme inhibitor

Energy Technology Data Exchange (ETDEWEB)

Ahmed, Khan Behlol Ayaz; Raman, Thiagarajan, E-mail: raman@biotech.sastra.edu; Veerappan, Anbazhagan, E-mail: anbazhagan@scbt.sastra.edu

2016-11-01

Nanoparticles are being widely used as antibacterial agents with metal nanoparticles emerging as the most efficient antibacterial agents. There have been many studies which have reported the mechanism of antibacterial activity of nanoparticles on bacteria. In this review we aim to emphasize on all the possible mechanisms which are involved in the antibacterial activity of nanoparticles and also to understand their mode of action and role as bacterial enzyme inhibitor by comparing their antibacterial mechanism to that of antibiotics with enzyme inhibition as a major mechanism. With the emergence of widespread antibiotic resistance, nanoparticles offer a better alternative to our conventional arsenal of antibiotics. Once the biological safety of these nanoparticles is addressed, these nanoparticles can be of great medical importance in our fight against bacterial infections. - Highlights: • Mechanisms of antibiotics and metal nanoparticles resemble one another. • Bactericidal mechanisms of NPs are cell wall damage, and ROS generation. • Metal NPs inhibit membrane synthesis enzyme. • NPs can be used as antibacterial agents. • NP as antibacterial strategy important due to widespread antibiotic resistance.

Pulmonary toxicity of well-dispersed titanium dioxide nanoparticles following intratracheal instillation

International Nuclear Information System (INIS)

Yoshiura, Yukiko; Izumi, Hiroto; Oyabu, Takako; Hashiba, Masayoshi; Kambara, Tatsunori; Mizuguchi, Yohei; Lee, Byeong Woo; Okada, Takami; Tomonaga, Taisuke; Myojo, Toshihiko; Yamamoto, Kazuhiro; Kitajima, Shinichi; Horie, Masanori; Kuroda, Etsushi; Morimoto, Yasuo

2015-01-01

In order to investigate the pulmonary toxicity of titanium dioxide (TiO 2 ) nanoparticles, we performed an intratracheal instillation study with rats of well-dispersed TiO 2 nanoparticles and examined the pulmonary inflammation and histopathological changes in the lung. Wistar Hannover rats were intratracheally administered 0.2 mg (0.66 mg/kg) and 1.0 mg (3.3 mg/kg) of well-dispersed TiO 2 nanoparticles (P90; diameter of agglomerates: 25 nm), then the pulmonary inflammation responses were examined from 3 days to 6 months after the instillation, and the pathological features were examined up to 24 months. Transient inflammation and the upregulation of chemokines in the broncho-alveolar lavage fluid were observed for 1 month. No respiratory tumors or severe fibrosis were observed during the recovery time. These data suggest that transient inflammation induced by TiO 2 may not lead to chronic, irreversible legions in the lung, and that TiO 2 nanoparticles may not have a high potential for lung disorder

Pulmonary toxicity of well-dispersed titanium dioxide nanoparticles following intratracheal instillation

Energy Technology Data Exchange (ETDEWEB)

Yoshiura, Yukiko, E-mail: y-yoshiura@med.uoeh-u.ac.jp; Izumi, Hiroto [University of Occupational and Environmental Health, Department of Occupational Pneumology, Institute of Industrial Ecological Science (Japan); Oyabu, Takako [University of Occupational and Environmental Health, Department of Environmental Health Engineering, Institute of Industrial Ecological Sciences (Japan); Hashiba, Masayoshi; Kambara, Tatsunori [University of Occupational and Environmental Health, Department of Occupational Pneumology, Institute of Industrial Ecological Science (Japan); Mizuguchi, Yohei; Lee, Byeong Woo; Okada, Takami [University of Occupational and Environmental Health, Department of Environmental Health Engineering, Institute of Industrial Ecological Sciences (Japan); Tomonaga, Taisuke [University of Occupational and Environmental Health, Department of Occupational Pneumology, Institute of Industrial Ecological Science (Japan); Myojo, Toshihiko [University of Occupational and Environmental Health, Department of Environmental Health Engineering, Institute of Industrial Ecological Sciences (Japan); Yamamoto, Kazuhiro [National Institute of Advanced Industrial Science and Technology (AIST) (Japan); Kitajima, Shinichi [National Sanatorium Hoshizuka Keiaien (Japan); Horie, Masanori [National Institute of Advanced Industrial Science and Technology (AIST), Health Research Institute (HRI) (Japan); Kuroda, Etsushi [Osaka University, Laboratory of Vaccine Science, WPI Immunology Frontier Research Center (Japan); Morimoto, Yasuo [University of Occupational and Environmental Health, Department of Occupational Pneumology, Institute of Industrial Ecological Science (Japan)

2015-06-15

In order to investigate the pulmonary toxicity of titanium dioxide (TiO{sub 2}) nanoparticles, we performed an intratracheal instillation study with rats of well-dispersed TiO{sub 2} nanoparticles and examined the pulmonary inflammation and histopathological changes in the lung. Wistar Hannover rats were intratracheally administered 0.2 mg (0.66 mg/kg) and 1.0 mg (3.3 mg/kg) of well-dispersed TiO{sub 2} nanoparticles (P90; diameter of agglomerates: 25 nm), then the pulmonary inflammation responses were examined from 3 days to 6 months after the instillation, and the pathological features were examined up to 24 months. Transient inflammation and the upregulation of chemokines in the broncho-alveolar lavage fluid were observed for 1 month. No respiratory tumors or severe fibrosis were observed during the recovery time. These data suggest that transient inflammation induced by TiO{sub 2} may not lead to chronic, irreversible legions in the lung, and that TiO{sub 2} nanoparticles may not have a high potential for lung disorder.

Facile solid-state synthesis of oxidation-resistant metal nanoparticles at ambient conditions

Science.gov (United States)

Lee, Kyu Hyung; Jung, Hyuk Joon; Lee, Ju Hee; Kim, Kyungtae; Lee, Byeongno; Nam, Dohyun; Kim, Chung Man; Jung, Myung-Hwa; Hur, Nam Hwi

2018-05-01

A simple and scalable method for the synthesis of metal nanoparticles in the solid-state was developed, which can produce nanoparticles in the absence of solvents. Nanoparticles of coinage metals were synthesized by grinding solid hydrazine and the metal precursors in their acetates and oxides at 25 °C. The silver and gold acetates converted completely within 6 min into Ag and Au nanoparticles, respectively, while complete conversion of the copper acetate to the Cu sub-micrometer particles took about 2 h. Metal oxide precursors were also converted into metal nanoparticles by grinding alone. The resulting particles exhibit distinctive crystalline lattice fringes, indicating the formation of highly crystalline phases. The Cu sub-micrometer particles are better resistant to oxidation and exhibit higher conductivity compared to conventional Cu nanoparticles. This solid-state method was also applied for the synthesis of platinum group metals and intermetallic Cu3Au, which can be further extended to synthesize other metal nanoparticles.

Environmentally friendly preparation of metal nanoparticles

Science.gov (United States)

The book chapter summarizes the “state of the art” in the exploitation of various environmentally-friendly synthesis approaches, reaction precursors and conditions to manufacture metal and metal oxide nanoparticles for a vast variety of purposes.

Metal-doped semiconductor nanoparticles and methods of synthesis thereof

Science.gov (United States)

Ren, Zhifeng (Inventor); Chen, Gang (Inventor); Poudel, Bed (Inventor); Kumar, Shankar (Inventor); Wang, Wenzhong (Inventor); Dresselhaus, Mildred (Inventor)

2009-01-01

The present invention generally relates to binary or higher order semiconductor nanoparticles doped with a metallic element, and thermoelectric compositions incorporating such nanoparticles. In one aspect, the present invention provides a thermoelectric composition comprising a plurality of nanoparticles each of which includes an alloy matrix formed of a Group IV element and Group VI element and a metallic dopant distributed within the matrix.

Evaluation of Antibacterial Properties of Dental Adhesives Containing Metal Nanoparticles

Directory of Open Access Journals (Sweden)

Shafiei F

2018-03-01

Full Text Available Statement of problem: Secondary dental caries is a common clinical finding in composite restoration. The development of a bactericidal dental adhesive provides a promising method to reduce the risk of secondary caries. Objectives: This study aimed to assess the antibacterial activity of silver (Ag and titanium dioxide (TiO2 nanoparticles incorporated into an experimental dentin bonding agent formulation. Materials and Methods: Ag and TiO2 nanoparticles at 0.05, 0.1, 0.2, 0.5, and 1 wt% concentrations were incorporated into the adhesives. The suspensions were sonicated to ensure homogenous dispersion of nanoparticles in the adhesive system. Formulation was composed of acetone, 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxyphenyl]propane (Bis-GMA, 1,6-bis-[2-methacryloyloxyethyl carbonyl amino]-2,4,4-trimethylhexane (UDMA, trimethylolpropane trimethacrylate (TMPTMA, 2-hydroxyethyl methacrylate (HEMA, and photoinitiator, with polyvinylpyrrolidone (PVP as the stabilizer. We counted the colony-forming units (CFU% of two cariogenic bacteria, Streptococcus mutans (S. mutans and Lactobacillus acidophilus (L. acidophilus, that were exposed to the powdered light cured adhesive specimens. The effects of various concentrations of each nanoparticle were compared by one-way ANOVA, followed by the post hoc Bonferroni test. Results: All samples exhibited definite antibacterial activity (P<0.05 compared to the control specimens. The Ag nanoparticle samples showed higher antibacterial properties compared to the TiO2 nanoparticle samples. Increasing the concentration of nanoparticles resulted in significant differences in bactericidal properties, with the exception of 0.2 to 0.5 wt% Ag nanoparticle specimens exposed to S. mutans and the 0.2 to 0.5 wt% TiO2 nanoparticle specimens exposed to L. acidophilus. Conclusions: These metal-based nanoparticles exhibited dose-dependent bactericidal activities. The Ag nanoparticles had higher antibacterial activity compared to the

Curvature dependence of the effect of ionic functionalization on the attraction among nanoparticles in dispersion

Science.gov (United States)

Jabes, B. Shadrack; Bratko, Dusan; Luzar, Alenka

2018-06-01

Solubilization of nanoparticles facilitates nanomaterial processing and enables new applications. An effective method to improve dispersibility in water is provided by ionic functionalization. We explore how the necessary extent of functionalization depends on the particle geometry. Using molecular dynamics/umbrella sampling simulations, we determine the effect of the solute curvature on solvent-averaged interactions among ionizing graphitic nanoparticles in aqueous dispersion. We tune the hydrophilicity of molecular-brush coated fullerenes, carbon nanotubes, and graphane platelets by gradually replacing a fraction of the methyl end groups of the alkyl coating by the ionizing -COOK or -NH3Cl groups. To assess the change in nanoparticles' dispersibility in water, we determine the potential-of-mean-force profiles at varied degrees of ionization. When the coating comprises only propyl groups, the attraction between the hydrophobic particles intensifies from spherical to cylindrical to planar geometry. This is explained by the increasing fraction of surface groups that can be brought into contact and the reduced access to water molecules, both following the above sequence. When ionic groups are added, however, the dispersibility increases in the opposite order, with the biggest effect in the planar geometry and the smallest in the spherical geometry. These results highlight the important role of geometry in nanoparticle solubilization by ionic functionalities, with about twice higher threshold surface charge necessary to stabilize a dispersion of spherical than planar particles. At 25%-50% ionization, the potential of mean force reaches a plateau because of the counterion condensation and saturated brush hydration. Moreover, the increase in the fraction of ionic groups can weaken the repulsion through counterion correlations between adjacent nanoparticles. High degrees of ionization and concomitant ionic screening gradually reduce the differences among surface

Thermally stable nanoparticles on supports

Science.gov (United States)

Roldan Cuenya, Beatriz; Naitabdi, Ahmed R.; Behafarid, Farzad

2012-11-13

An inverse micelle-based method for forming nanoparticles on supports includes dissolving a polymeric material in a solvent to provide a micelle solution. A nanoparticle source is dissolved in the micelle solution. A plurality of micelles having a nanoparticle in their core and an outer polymeric coating layer are formed in the micelle solution. The micelles are applied to a support. The polymeric coating layer is then removed from the micelles to expose the nanoparticles. A supported catalyst includes a nanocrystalline powder, thin film, or single crystal support. Metal nanoparticles having a median size from 0.5 nm to 25 nm, a size distribution having a standard deviation .ltoreq.0.1 of their median size are on or embedded in the support. The plurality of metal nanoparticles are dispersed and in a periodic arrangement. The metal nanoparticles maintain their periodic arrangement and size distribution following heat treatments of at least 1,000.degree. C.

A simple urea-based route to ternary metal oxynitride nanoparticles

International Nuclear Information System (INIS)

Gomathi, A.; Reshma, S.; Rao, C.N.R.

2009-01-01

Ternary metal oxynitrides are generally prepared by heating the corresponding metal oxides with ammonia for long durations at high temperatures. In order to find a simple route that avoids use of gaseous ammonia, we have employed urea as the nitriding agent. In this method, ternary metal oxynitrides are obtained by heating the corresponding metal carbonates and transition metal oxides with excess urea. By this route, ternary metal oxynitrides of the formulae MTaO 2 N (M=Ca, Sr or Ba), MNbO 2 N (M=Sr or Ba), LaTiO 2 N and SrMoO 3-x N x have been prepared successfully. The oxynitrides so obtained were generally in the form of nanoparticles, and were characterized by various physical techniques. - Graphical abstract: Nanoparticles of ternary metal oxynitrides can be synthesized by means of urea route. Given is the TEM image of the nanoparticles of CaTaO 2 N so obtained and the insets show the SAED pattern and HREM image of the nanoparticles

Nanoparticle dispersion in environmentally relevant culture media: a TiO2 case study and considerations for a general approach

International Nuclear Information System (INIS)

Horst, Allison M.; Ji, Zhaoxia; Holden, Patricia A.

2012-01-01

Nanoparticle exposure in toxicity studies requires that nanoparticles are bioavailable by remaining highly dispersed in culture media. However, reported dispersion approaches are variable, mostly study-specific, and not transferable owing to their empirical basis. Furthermore, many published approaches employ proteinaceous dispersants in rich laboratory media, both of which represent end members in environmental scenarios. Here, a systematic approach was developed to disperse initially agglomerated TiO 2 nanoparticles (Aeroxide® TiO 2 P25, Evonik, NJ; primary particle size range 6.4–73.8 nm) in oligotrophic culture medium for environmentally relevant bacterial toxicity studies. Based on understanding particle–particle interactions in aqueous media and maintaining environmental relevance, the approach involves (1) quantifying the relationship between pH and zeta potential to determine the point of zero charge of select nanoparticles in water; (2) nominating, then testing and selecting, environmentally relevant stabilizing agents; and (3) dispersing via “condition and capture” whereby stock dry powder nanoparticles are sonicated in pre-conditioned (with base, or acid, plus stabilizing agent) water, then diluted into culture media. The “condition and capture” principle is transferable to other nanoparticle and media chemistries: simultaneously, mechanically and electrostatically, nanoparticles can be dispersed with surrounding stabilizers that coat and sterically hinder reagglomeration in the culture medium.

Radiation chemical route for preparation of metal nanoparticles

International Nuclear Information System (INIS)

Kapoor, S.; Mukherjee, T.

2006-01-01

Nanoparticles show properties that are neither seen in the bulk or at atomic level. The unusual properties are governed by quantum size effect. Due to this various methodologies have been endeavored to control the size of the particles. In the present work we show the use of two complimentary techniques (radiation and photo) to synthesize and control the size of the metal particles. In-situ synthesis of fine silver, thallium and cadmium particles has been carried out by gamma-irradiation and electron pulse irradiation at room temperature in the pre-organized gel of polyacrylamide or cyclodextrin cavity. The role of generation of nuclei in high concentrations in stabilization of metal nanoparticles in hydrophobic cavity is shown. Similarly the importance of entrapment of metal ions in the polymer matrix during its formation is highlighted. The work is further extended to exploit the microemulsion droplets for stabilization of Cd nanoparticles. Utility of pulse radiolysis in probing the mechanism of the formation of metal nanoparticles is also shown. Ultrafast laser pulses were employed to control the morphology of the pre-prepared Pt nanoparticles. The changes in reduction of shape and size are considered to occur through melting and vaporization of the nanoparticles. Pt nanoparticles were coated on the inner walls of the tubular pyrex reactor and tested for their catalytic activity for oxidation of CO. It was observed that Pt nanoparticles prepared in the presence of a stabilizer (gelatin) showed a higher tendency to adhere to the inner walls of the pyrex reactor as compared to that prepared in the presence of silica nanoparticles. The catalyst was found to be active at ≥150 degree C giving CO 2 . Chemically reduced Pt nanoparticles stabilized on silica nanoparticles gave ∼7% CO conversion per hr. However, radiolytically prepared Pt nanoaprticles stabilized by gelatin gave ∼10% conversion per hr. The data indicates that catalytic oxidation of CO takes place

Metal Nanoparticles as Targeted Carriers Circumventing the Blood-Brain Barrier.

Science.gov (United States)

Sintov, A C; Velasco-Aguirre, C; Gallardo-Toledo, E; Araya, E; Kogan, M J

2016-01-01

Metal nanoparticles have been proposed as a carrier and a therapeutic agent in biomedical field because of their unique physiochemical properties. Due to these physicochemical properties, they can be used in different fields of biomedicine. In relation to this, plasmonic nanoparticles can be used for detection and photothermal destruction of tumor cells or toxic protein aggregates, and magnetic iron nanoparticles can be used for imaging and for hyperthermia of tumor cells. In addition, both therapy and imaging can be combined in one nanoparticle system, in a process called theranostics. Metal nanoparticles can be synthesized to modulate their size and shape, and conjugated with different ligands, which allow their application in drug delivery, diagnostics, and treatment of central nervous system diseases. This review is focused on the potential applications of metal nanoparticles and their capability to circumvent the blood-brain barrier (BBB). Although many articles have demonstrated delivery of metal nanoparticles to the brain by crossing the BBB after systemic administration, the percentage of the injected dose that reaches this organ is low in comparison to others, especially the liver and spleen. In connection with this drawback, we elaborate the architecture of the BBB and review possible mechanisms to cross this barrier by engineered nanoparticles. The potential uses of metal nanoparticles for treatment of disorders as well as related neurotoxicological considerations are also discussed. Finally, we bring up for discussion a direct and relatively simpler solution to the problem. We discuss this in detail after having proposed the use of the intranasal administration route as a way to circumvent the BBB. This route has not been extensively studied yet for metal nanoparticles, although it could be used as a research tool for mechanistic understanding and toxicity as well as an added value for medical practice. © 2016 Elsevier Inc. All rights reserved.

Manufacturing Nanoparticles with Orthogonally Adjustable Dispersibility in Hydrocarbons, Fluorocarbons, and Water.

Science.gov (United States)

Zeininger, Lukas; Stiegler, Lisa M S; Portilla, Luis; Halik, Marcus; Hirsch, Andreas

2018-04-01

Invited for this month's cover picture is the group of Prof. Dr. Andreas Hirsch from Friedrich Alexander University (Germany). The cover picture shows shell-by-shell coated nanoparticle 'chameleons'-wet-chemically surface-modified nanoparticles that can reversibly adjust their dispersibility to entirely orthogonal solvent environments. Read the full text of their Full Paper at https://doi.org/10.1002/open.201800011.

A Study On Dispersion Stability Of Nickel Nanoparticles Synthesized By Wire Explosion In Liquid Media

Directory of Open Access Journals (Sweden)

Kim C.K.

2015-06-01

Full Text Available In this study, nickel nanoparticles were synthesized in ethanol using portable pulsed wire evaporation, which is a one-step physical method. From transmission electron microscopy images, it was found that the Ni nanoparticles exhibited a spherical shape with an average diameter of 7.3 nm. To prevent aggregation of the nickel nanoparticles, a polymer surfactant was added into the ethanol before the synthesis of nickel nanoparticles, and adsorbed on the freshly synthesized nickel nanoparticles during the wire explosion. The dispersion stability of the prepared nickel nanofluids was investigated by zeta-potential analyzer and Turbiscan optical analyzer. As a result, the optimum concentration of polymer surfactant to be added was suggested for the maximized dispersion stability of the nickel nanofluids.

Catalyst Architecture for Stable Single Atom Dispersion Enables Site-Specific Spectroscopic and Reactivity Measurements of CO Adsorbed to Pt Atoms, Oxidized Pt Clusters, and Metallic Pt Clusters on TiO2.

Science.gov (United States)

DeRita, Leo; Dai, Sheng; Lopez-Zepeda, Kimberly; Pham, Nicholas; Graham, George W; Pan, Xiaoqing; Christopher, Phillip

2017-10-11

Oxide-supported precious metal nanoparticles are widely used industrial catalysts. Due to expense and rarity, developing synthetic protocols that reduce precious metal nanoparticle size and stabilize dispersed species is essential. Supported atomically dispersed, single precious metal atoms represent the most efficient metal utilization geometry, although debate regarding the catalytic activity of supported single precious atom species has arisen from difficulty in synthesizing homogeneous and stable single atom dispersions, and a lack of site-specific characterization approaches. We propose a catalyst architecture and characterization approach to overcome these limitations, by depositing ∼1 precious metal atom per support particle and characterizing structures by correlating scanning transmission electron microscopy imaging and CO probe molecule infrared spectroscopy. This is demonstrated for Pt supported on anatase TiO 2 . In these structures, isolated Pt atoms, Pt iso , remain stable through various conditions, and spectroscopic evidence suggests Pt iso species exist in homogeneous local environments. Comparing Pt iso to ∼1 nm preoxidized (Pt ox ) and prereduced (Pt metal ) Pt clusters on TiO 2 , we identify unique spectroscopic signatures of CO bound to each site and find CO adsorption energy is ordered: Pt iso ≪ Pt metal atoms bonded to TiO 2 and that Pt iso exhibits optimal reactivity because every atom is exposed for catalysis and forms an interfacial site with TiO 2 . This approach should be generally useful for studying the behavior of supported precious metal atoms.

Enhanced specific heat capacity of molten salt-based nanomaterials: Effects of nanoparticle dispersion and solvent material

International Nuclear Information System (INIS)

Jo, Byeongnam; Banerjee, Debjyoti

2014-01-01

This study investigated the effect of nanoparticle dispersion on the specific heat capacity for carbonate salt mixtures doped with graphite nanoparticles. The effect of the solvent material was also examined. Binary carbonate salt mixtures consisting of lithium carbonate and potassium carbonate were used as the base material for the graphite nanomaterial. The different dispersion uniformity of the nanoparticles was created by employing two distinct synthesis protocols for the nanomaterial. Different scanning calorimetry was employed to measure the specific heat capacity in both solid and liquid phases. The results showed that doping the molten salt mixture with the graphite nanoparticles significantly raised the specific heat capacity, even in minute concentrations of graphite nanoparticles. Moreover, greater enhancement in the specific heat capacity was observed from the nanomaterial samples with more homogeneous dispersion of the nanoparticles. A molecular dynamics simulation was also performed for the nanomaterials used in the specific heat capacity measurements to explain the possible mechanisms for the enhanced specific heat capacity, including the compressed layering and the species concentration of liquid solvent molecules

Characterization of a dielectric microdroplet thermal interface material with dispersed nanoparticles

International Nuclear Information System (INIS)

Hamdan, A.; Sahli, F.; Richards, R.; Richards, C.

2012-01-01

This work presents the fabrication and characterization of a dielectric microdroplet thermal interface material (TIM). Glycerin droplets, 1 μL, were tested as TIMs in this study. Copper nanoparticles having a diameter of 25 nm were dispersed in glycerin at different volume fractions to enhance its thermal conductivity. An increase of 57.5% in the thermal conductivity of glycerin was measured at a volume fraction of 15%. A minimum thermal interface resistance of 30.37 mm 2 K/W was measured for the glycerin microdroplets at a deformed droplet height of 10.2 μm. Good agreement between experimental measurements and the predictions of a model based on Maxwell’s equation of rules of mixtures was obtained. The effect of nanoparticles' size on the effective thermal conductivity of glycerin was studied. Nanoparticles with diameters of 60–80 and 300 nm were dispersed in glycerin at a volume fraction of 5%, and their results were compared to those of the 25 nm particles.

Hydrothermal Synthesis of Highly Water-dispersible Anatase Nanoparticles with Large Specific Surface Area and Their Adsorptive Properties

Directory of Open Access Journals (Sweden)

Hu Xueting

2016-01-01

Full Text Available Highly water-dispersible and very small TiO2 nanoparticles (~3 nm anatase with large specific surface area have been synthesized by hydrolysis and hydrothermal reactions of titanium butoxide and used for the removal of three azo dyes (Congo red, orange II, and methyl orange with different molecular structure from simulated wastewaters. The synthesized TiO2 nanoparticles are well dispersed in water with large specific surface area up to 417 m2 g−1. Adsorption experiments demonstrated that the water-dispersible TiO2 nanoparticles possess excellent adsorption capacities for Congo red, orange II, and methyl orange, which could be attributed to their good water-dispersibility and large specific surface area.

Nanoparticle dispersion effect of laser-surface melting in ZrB{sub 2p}/6061Al composites

Energy Technology Data Exchange (ETDEWEB)

Zeng, Yida; Chao, Yuhjin; Luo, Zhen, E-mail: lz-tju@163.com [Tianjin University, School of Material Science and Engineering (China); Huang, Yongxian [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology (China)

2017-04-15

Zirconium diboride (ZrB{sub 2p}, 15 vol%)/6061 aluminum (Al) composites were fabricated via in situ reaction. The existence, morphologies, and dispersion degree of the in situ ZrB{sub 2} particles with size from tens to hundreds of nanometers were studied by X-ray diffractometry, energy-dispersive X-ray spectroscopy, field-emission scanning electron microscopy, and high-resolution transmission electron microscopy. As the particle-settlement effect becomes dominant during the composite fabrication process, ZrB{sub 2} nanoparticles agglomerate to a certain extent in some areas of the as-cast composites. A laser-surface melting (LSM) strategy was applied to disperse agglomerated ZrB{sub 2} nanoparticles in as-cast composites, and the ZrB{sub 2} nanoparticle dispersion is affected visibly by LSM. After LSM, nanoparticles tend to distribute along the grain boundary. Particle clusters were dispersed in an explosive orientation and the particle diffusion distance varied in terms of its radius and melt-viscosity vicinity. High-resolution transmission electron microscopy showed the existence of a subgrain structure near the ZrB{sub 2}–Al interface after LSM. This may increase the yield strength when a dislocation tangle forms.

Computational studies of adsorption in metal organic frameworks and interaction of nanoparticles in condensed phases

Energy Technology Data Exchange (ETDEWEB)

Annapureddy, HVR; Motkuri, RK; Nguyen, PTM; Truong, TB; Thallapally, PK; McGrail, BP; Dang, LX

2014-02-05

In this review, we describe recent efforts to systematically study nano-structured metal organic frameworks (MOFs), also known as metal organic heat carriers, with particular emphasis on their application in heating and cooling processes. We used both molecular dynamics and grand canonical Monte Carlo simulation techniques to gain a molecular-level understanding of the adsorption mechanism of gases in these porous materials. We investigated the uptake of various gases such as refrigerants R12 and R143a. We also evaluated the effects of temperature and pressure on the uptake mechanism. Our computed results compared reasonably well with available measurements from experiments, thus validating our potential models and approaches. In addition, we investigated the structural, diffusive and adsorption properties of different hydrocarbons in Ni-2(dhtp). Finally, to elucidate the mechanism of nanoparticle dispersion in condensed phases, we studied the interactions among nanoparticles in various liquids, such as n-hexane, water and methanol.

Stabilizing ability of surfactant on physicochemical properties of drug nanoparticles generated from solid dispersions.

Science.gov (United States)

Thongnopkoon, Thanu; Puttipipatkhachorn, Satit

2017-07-01

This study was aimed to examine the nanoparticle formation from redispersion of binary and ternary solid dispersions. Binary systems are composed of various ratios of glibenclamide (GBM) and polyvinylpyrrolidone K30 (PVP-K30), whereas a constant amount at 2.5%w/w of a surfactant, sodium lauryl sulfate (SLS) or Gelucire44/14 (GLC), was added to create ternary systems. GBM nanoparticles were collected after the systems were dispersed in water for 15 min. The obtained nanoparticles were characterized for size distribution, crystallinity, thermal behavior, molecular structure, and dissolution properties. The results indicated that GBM nanoparticles could be formed when the drug content of the systems was lower than 30%w/w in binary systems and ternary systems containing SLS. The particle size ranged from 200 to 500 nm in diameter with narrow size distribution. The particle size was increased with increasing drug content in the systems. The obtained nanoparticles were spherical and showed the amorphous state. Furthermore, because of being amorphous form and reduced particle size, the dissolution of the generated nanoparticles was markedly improved compared with the GBM powder. In contrast, all the ternary solid dispersions prepared with GLC anomalously provided the crystalline particles with the size ranging over 5 µm and irregular shape. Interestingly, this was irrelevant to the drug content in the systems. These results indicated the ability of GLC to destabilize the polymer network surrounding the particles during particle precipitation. Therefore, this study suggested that drug content, quantity, and type of surfactant incorporated in solid dispersions drastically affected the physicochemical properties of the precipitated particles.

Determination of the size distribution of metallic nanoparticles by optical extinction spectroscopy

International Nuclear Information System (INIS)

Pena, Ovidio; Rodriguez-Fernandez, Luis; Rodriguez-Iglesias, Vladimir; Kellermann, Guinther; Crespo-Sosa, Alejandro; Cheang-Wong, Juan Carlos; Silva-Pereyra, Hector Gabriel; Arenas-Alatorre, Jesus; Oliver, Alicia

2009-01-01

A method is proposed to estimate the size distribution of nearly spherical metallic nanoparticles (NPs) from optical extinction spectroscopy (OES) measurements based on Mie's theory and an optimization algorithm. The described method is compared against two of the most widely used techniques for the task: transmission electron microscopy (TEM) and small-angle x-ray scattering (SAXS). The size distribution of Au and Cu NPs, obtained by ion implantation in silica and a subsequent thermal annealing in air, was determined by TEM, grazing-incidence SAXS (GISAXS) geometry, and our method, and the average radius obtained by all the three techniques was almost the same for the two studied metals. Concerning the radius dispersion (RD), OES and GISAXS give very similar results, while TEM considerably underestimates the RD of the distribution

Co-Immobilization of Enzymes and Magnetic Nanoparticles by Metal-Nucleotide Hydrogelnanofibers for Improving Stability and Recycling

Directory of Open Access Journals (Sweden)

Chunfang Li

2017-01-01

Full Text Available In this paper we report a facile method for preparing co-immobilized enzyme and magnetic nanoparticles (MNPs using metal coordinated hydrogel nanofibers. Candida rugosa lipase (CRL was selected as guest protein. For good aqueous dispersity, low price and other unique properties, citric acid-modified magnetic iron oxide nanoparticles (CA-Fe3O4 NPs have been widely used for immobilizing enzymes. As a result, the relative activity of CA-Fe3O4@Zn/AMP nanofiber-immobilized CRL increased by 8-fold at pH 10.0 and nearly 1-fold in a 50 °C water bath after 30 min, compared to free CRL. Moreover, the immobilized CRL had excellent long-term storage stability (nearly 80% releative activity after storage for 13 days. This work indicated that metal-nucleotide nanofibers could efficiently co-immobilize enzymes and MNPs simultaneously, and improve the stability of biocatalysts.

Structural investigation of biogenic ferrihydrite nanoparticles dispersion

International Nuclear Information System (INIS)

Balasoiu, M.; Ishchenko, L.A.; Stolyar, S.V.; Iskhakov, R.S.; Rajkher, Yu.L.; Kuklin, A.I.; Solov'ev, D.V.; Arzumanyan, G.M.; Kurkin, T.S.; Aranghel, D.

2010-01-01

Structural properties of biogenic ferrihydrite nanoparticles produced by bacteria Klebsiella oxytoca are investigated. Investigations of morphology and size of particles dispersed in water by means of high-resolution transmission electron microscopy and small angle X-ray scattering measurements were performed. By model calculations followed by fitting procedure the structural parameters of a cylinder of radius R = (4.87 ± 0.02) nm and height L = (2.12 ± 0.04) nm are obtained

Analysis of polariton dispersion in metal nanocomposite based novel superlattice system

Science.gov (United States)

DoniPon, V.; Joseph Wilson, K. S.; Malarkodi, A.

2018-06-01

The influence of metal nanoparticles in tuning the polaritonic gap in a novel piezoelectric superlattice is studied. Dielectric function of the metal nanoparticles is analyzed using Kawabata-Kubo effect and Drude's theory. The effective dielectric function of the nanocomposite system is studied using Maxwell Garnett approximation. Nanocomposite based LiTaO3 novel superlattice is formed by arranging the nanocomposite systems in such a way that their orientations are in the opposite direction. Hence there are two additional modes of propagation. The top most modes reflect the metal behavior of the nanoparticles. It is found that these modes of propagation vary with the filling factor. These additional modes of propagations can be exploited in the field of communication.

“Green” Nanotechnologies: Synthesis of Metal Nanoparticles Using Plants

OpenAIRE

Makarov, V. V.; Love, A. J.; Sinitsyna, O. V.; Makarova, S. S.; Yaminsky, I. V.; Taliansky, M. E.; Kalinina, N. O.

2014-01-01

While metal nanoparticles are being increasingly used in many sectors of the economy, there is growing interest in the biological and environmental safety of their production. The main methods for nanoparticle production are chemical and physical approaches that are often costly and potentially harmful to the environment. The present review is devoted to the possibility of metal nanoparticle synthesis using plant extracts. This approach has been actively pursued in recent years as an alternat...

In situ generation of Ni nanoparticles from metal-organic framework precursors and their use for biomass hydrodeoxygenation.

Science.gov (United States)

Čelič, Tadeja Birsa; Grilc, Miha; Likozar, Blaž; Tušar, Nataša Novak

2015-05-22

So far, in situ-generated Ni nanoparticles have been reported to be efficient catalysts for tar cracking during wood liquefaction by pyrolysis. Herein, their performance in further bio-oil conversion steps is evaluated. Nanoparticles were generated for the first time from a Ni-containing metal-organic framework, MIL-77, during the hydrotreatment of glycerol-solvolyzed lignocellulosic (LC) biomass. Reactions were conducted at 300 °C and the H2 pressure was 8 MPa in a slurry reactor. The catalytic activity and selectivity of the deoxygenation and hydrocracking reactions for real biomass-derived feedstock using in situ-generated nanoparticles was compared with Ni nanoparticles dispersed on a silica-alumina support (commercial Ni/SiO2 -Al2 O3 catalyst). The mass activity of the in situ-generated nanoparticles for hydrogenolysis was more than ten times higher in comparison to their commercial analogues, and their potential for the use in LC biorefinery is discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and electrochemical characterization of stabilized nickel nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Dominguez-Crespo, M.A.; Ramirez-Meneses, E.; Torres Huerta, A.M. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, CICATA-IPN Unidad Altamira, Carretera Tampico-Puerto Industrial, C.P. 89600 Altamira, Tamaulipas (Mexico); Montiel-Palma, V. [Centro de Investigaciones Quimicas, Universidad Autonoma del Estado de Morelos, Av. Universidad 1001, Colonia Chamilpa, C.P.62201 Cuernavaca, Morelos (Mexico); Dorantes Rosales, H. [Departamento de Metalurgia, Escuela Superior de Ingenieria Quimica e Industrias Extractivas - IPN, C.P. 07300, D.F. (Mexico)

2009-02-15

Nickel stabilized nanoparticles produced by an organometallic approach (Chaudret's method) starting from the complex Ni(1,5-COD){sub 2} were used as electrode materials for hydrogen evolution in NaOH at two temperatures (298 and 323 K). The synthesis of the nickel nanoparticles was performed in the presence of two different stabilizers, 1,3-diaminopropane (DAP) and anthranilic acid (AA), by varying the molar ratios (1:1, 1:2 and 1:5 metal:ligand) in order to evaluate their influence on the shape, dispersion, size and electrocatalytic activity of the metallic particles. The presence of an appropriate amount of stabilizer is an effective alternative to the synthesis of small monodispersed metal nanoparticles with diameters around 5 and 8 nm for DAP and AA, respectively. The results are discussed in terms of morphology and the surface state of the nanoparticles. The importance of developing a well-controlled synthetic method which results in higher performances of the resulting nanoparticles is highlighted. Herein we found that the performance with respect to the HER of the Ni electrodes dispersed on a carbon black Vulcan substrate is active and comparable to that reported in the literature for the state-of-the-art electrocatalysts. Appreciable cathodic current densities of {proportional_to}240 mA cm{sup -2} were measured with highly dispersed nickel particles (Ni-5{sub DAP}). This work demonstrates that the aforementioned method can be extended to the preparation of highly active stabilized metal particles without inhibiting the electron transfer for the HER reaction, and it could also be applied to the synthesis of bimetallic nanoparticles. (author)

Marine microorganisms as potential biofactories for synthesis of metallic nanoparticles.

Science.gov (United States)

Manivasagan, Panchanathan; Nam, Seung Yun; Oh, Junghwan

2016-11-01

The use of marine microorganisms as potential biofactories for green synthesis of metallic nanoparticles is a relatively new field of research with considerable prospects. This method is eco-friendly, time saving, and inexpensive and can be easily scaled up for large-scale synthesis. The increasing need to develop simple, nontoxic, clean, and environmentally safe production methods for nanoparticles and to decrease environmental impact, minimize waste, and increase energy productivity has become important in this field. Marine microorganisms are tiny organisms that live in marine ecosystems and account for >98% of biomass of the world's ocean. Marine microorganisms synthesize metallic nanoparticles either intracellularly or extracellularly. Marine microbially-produced metallic nanoparticles have received considerable attention in recent years because of their expected impact on various applications such as medicine, energy, electronic, and space industries. The present review discusses marine microorganisms as potential biofactories for the green synthesis of metallic nanoparticles and their potential applications.

Water dispersible superparamagnetic Cobalt iron oxide nanoparticles for magnetic fluid hyperthermia

Energy Technology Data Exchange (ETDEWEB)

Salunkhe, Ashwini B. [Centre for advanced materials research, Department of Physics, Savitribai Phule Pune University, Pune 411007 (India); Soft matter and molecular biophysics group, Department of Applied Physics, University of Santiago de Compostela, Santiago de Compostela (Spain); Khot, Vishwajeet M. [Department of Physics and Astronomy, University College London (United Kingdom); Ruso, Juan M. [Soft matter and molecular biophysics group, Department of Applied Physics, University of Santiago de Compostela, Santiago de Compostela (Spain); Patil, S.I., E-mail: patil@physics.unipune.ac.in [Centre for advanced materials research, Department of Physics, Savitribai Phule Pune University, Pune 411007 (India)

2016-12-01

Superparamagnetic nanoparticles of Cobalt iron oxide (CoFe{sub 2}O{sub 4}) are synthesized chemically, and dispersed in an aqueous suspension for hyperthermia therapy application. Different parameters such as magnetic field intensity, particle concentration which regulates the competence of CoFe{sub 2}O{sub 4} nanoparticle as a heating agents in hyperthermia are investigated. Specific absorption rate (SAR) decreases with increase in the particle concentration and increases with increase in applied magnetic field intensity. Highest value of SAR is found to be 91.84 W g{sup −1} for 5 mg. mL{sup −1} concentration. Oleic acid conjugated polyethylene glycol (OA-PEG) coated CoFe{sub 2}O{sub 4} nanoparticles have shown superior cyto-compatibility over uncoated nanoparticles to L929 mice fibroblast cell lines for concentrations below 2 mg. mL{sup −1}. Present work provides the underpinning for the use of CoFe{sub 2}O{sub 4} nanoparticles as a potential heating mediator for magnetic fluid hyperthermia. - Highlights: • Superparamagnetic, water dispersible CoFe{sub 2}O{sub 4} NPs were synthesized by simple and cost effective Co precipitation route. • Effect of coating on various physical and chemical properties of CoFe{sub 2}O{sub 4} NPs were studied. • The effect of coating on induction heating as well as biocompatibility of NPs were studied.

Microscopic Electron Dynamics in Metal Nanoparticles for Photovoltaic Systems

Directory of Open Access Journals (Sweden)

Katarzyna Kluczyk

2018-06-01

Full Text Available Nanoparticles—regularly patterned or randomly dispersed—are a key ingredient for emerging technologies in photonics. Of particular interest are scattering and field enhancement effects of metal nanoparticles for energy harvesting and converting systems. An often neglected aspect in the modeling of nanoparticles are light interaction effects at the ultimate nanoscale beyond classical electrodynamics. Those arise from microscopic electron dynamics in confined systems, the accelerated motion in the plasmon oscillation and the quantum nature of the free electron gas in metals, such as Coulomb repulsion and electron diffusion. We give a detailed account on free electron phenomena in metal nanoparticles and discuss analytic expressions stemming from microscopic (Random Phase Approximation—RPA and semi-classical (hydrodynamic theories. These can be incorporated into standard computational schemes to produce more reliable results on the optical properties of metal nanoparticles. We combine these solutions into a single framework and study systematically their joint impact on isolated Au, Ag, and Al nanoparticles as well as dimer structures. The spectral position of the plasmon resonance and its broadening as well as local field enhancement show an intriguing dependence on the particle size due to the relevance of additional damping channels.

Removal of Metal Nanoparticles Colloidal Solutions by Water Plants

Science.gov (United States)

Olkhovych, Olga; Svietlova, Nataliia; Konotop, Yevheniia; Karaushu, Olena; Hrechishkina, Svitlana

2016-11-01

The ability of seven species of aquatic plants ( Elodea canadensis, Najas guadelupensis, Vallisneria spiralis L., Riccia fluitans L., Limnobium laevigatum, Pistia stratiotes L., and Salvinia natans L.) to absorb metal nanoparticles from colloidal solutions was studied. It was established that investigated aquatic plants have a high capacity for removal of metal nanoparticles from aqueous solution (30-100%) which indicates their high phytoremediation potential. Analysis of the water samples content for elements including the mixture of colloidal solutions of metal nanoparticles (Mn, Cu, Zn, Ag + Ag2O) before and after exposure to plants showed no significant differences when using submerged or free-floating hydrophytes so-called pleuston. However, it was found that the presence of submerged hydrophytes in aqueous medium ( E. canadensis, N. guadelupensis, V. spiralis L., and R. fluitans L.) and significant changes in the content of photosynthetic pigments, unlike free-floating hydrophytes ( L. laevigatum, P. stratiotes L., S. natans L.), had occur. Pleuston possesses higher potential for phytoremediation of contaminated water basins polluted by metal nanoparticles. In terms of removal of nanoparticles among studied free-floating hydrophytes, P. stratiotes L. and S. natans L. deserve on special attention.

URANIUM BISMUTHIDE DISPERSION IN MOLTEN METAL

Science.gov (United States)

Teitel, R.J.

1959-10-27

The formation of intermetallic bismuth compounds of thorium or uranium dispersed in a liquid media containing bismuth and lead is described. A bismuthide of uranium dispersed in a liquid metal medium is formed by dissolving uranium in composition of lead and bismuth containing less than 80% lead and lowering the temperature of the composition to a temperature below the point at which the solubility of uranium is exceeded and above the melting point of the composition.

Effect of carrier gas composition on transferred arc metal nanoparticle synthesis

International Nuclear Information System (INIS)

Stein, Matthias; Kiesler, Dennis; Kruis, Frank Einar

2013-01-01

Metal nanoparticles are used in a great number of applications; an effective and economical production scaling-up is hence desirable. A simple and cost-effective transferred arc process is developed, which produces pure metal (Zn, Cu, and Ag) nanoparticles with high production rates, while allowing fast optimization based on energy efficiency. Different carrier gas compositions, as well as the electrode arrangements and the power input are investigated to improve the production and its efficiency and to understand the arc production behavior. The production rates are determined by a novel process monitoring method, which combines an online microbalance method with a scanning mobility particle sizer for fast production rate and size distribution measurement. Particle characterization is performed via scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction measurements. It is found that the carrier gas composition has the largest impact on the particle production rate and can increase it with orders of magnitude. This appears to be not only a result of the increased heat flux and melt temperature but also of the formation of tiny nitrogen (hydrogen) bubbles in the molten feedstock, which impacts feedstock evaporation significantly in bi-atomic gases. A production rate of sub 200 nm particles from 20 up to 2,500 mg/h has been realized for the different metals. In this production range, specific power consumptions as low as 0.08 kWh/g have been reached.

Metal nanoparticles in DBS card materials modification

Science.gov (United States)

Metelkin, A.; Frolov, G.; Kuznetsov, D.; Kolesnikov, E.; Chuprunov, K.; Kondakov, S.; Osipov, A.; Samsonova, J.

2015-11-01

In the recent years the method of collecting and storing Dried Blood Spots (DBS) on special cellulose membrane (paper) has gained wide popularity. But possible damage of biosamples caused by microorganisms in case of their incomplete drying is a disadvantage of the method. It can be overcome by treating sample-collection membranes with colloidal solutions of metal nanoparticles, having antibacterial effect. The team studied antibacterial properties of nonwoven material samples with various coatings (alcohol sols of copper, aluminium, iron, titanium, silver and vanadium nanoparticles). Colloidal solutions of nanoparticles were obtained by means of electroerosion method with further low-temperature plasma condensation. Antibacterial activity of fiberglass and cellulose membrane samples with nanoparticle coatings was studied using B. cereus and plaque bacteria cultures. It was revealed that nanostructured coatings can suppress bacterial activity; in addition they can diffuse from the membrane surface into medium which leads to widening the areas of inhibiting testing cultures’ growth. Thus, membrane materials treatment with alcohol-sols of metal nanoparticles can be seen as promising for conferring antibacterial properties to DBS carriers.

Metal nanoparticles in DBS card materials modification

International Nuclear Information System (INIS)

Metelkin, A; Frolov, G; Kuznetsov, D; Kolesnikov, E; Chuprunov, K; Kondakov, S; Osipov, A; Samsonova, J

2015-01-01

In the recent years the method of collecting and storing Dried Blood Spots (DBS) on special cellulose membrane (paper) has gained wide popularity. But possible damage of biosamples caused by microorganisms in case of their incomplete drying is a disadvantage of the method. It can be overcome by treating sample-collection membranes with colloidal solutions of metal nanoparticles, having antibacterial effect. The team studied antibacterial properties of nonwoven material samples with various coatings (alcohol sols of copper, aluminium, iron, titanium, silver and vanadium nanoparticles). Colloidal solutions of nanoparticles were obtained by means of electroerosion method with further low-temperature plasma condensation. Antibacterial activity of fiberglass and cellulose membrane samples with nanoparticle coatings was studied using B. cereus and plaque bacteria cultures. It was revealed that nanostructured coatings can suppress bacterial activity; in addition they can diffuse from the membrane surface into medium which leads to widening the areas of inhibiting testing cultures’ growth. Thus, membrane materials treatment with alcohol-sols of metal nanoparticles can be seen as promising for conferring antibacterial properties to DBS carriers. (paper)

Effect of strontium tantalate surface texture on nickel nanoparticle dispersion by electroless deposition

Energy Technology Data Exchange (ETDEWEB)

Compean-González, C.L. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Civil, Departamento de Ecomateriales y Energía, Av. Universidad s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León C.P. 66451 (Mexico); Arredondo-Torres, V.M. [Facultad de Químico Farmacobiología, Universidad Michoacana de San Nicolás de Hidalgo, Tzintzuntzan #173, Col. Matamoros, Morelia, Michoacán C.P. 58240 (Mexico); Zarazúa-Morin, M.E. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Civil, Departamento de Ecomateriales y Energía, Av. Universidad s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León C.P. 66451 (Mexico); Figueroa-Torres, M.Z., E-mail: m.zyzlila@gmail.com [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Civil, Departamento de Ecomateriales y Energía, Av. Universidad s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León C.P. 66451 (Mexico)

2015-09-15

Highlights: • Efficient short-time procedure for nickel nanoparticles dispersion by electroless. • Nanoparticles are spherical in shape with an average size of 15 nm. • Influence of surface texture on deposition temperature and time was observed. • Nickel deposition can be done below 50 °C. - Abstract: The present work studies the effect of smooth and porous texture of Sr{sub 2}Ta{sub 2}O{sub 7} on its surface modification with nickel nanoparticles through electroless deposition technique. The influence of temperature to control Ni nanoparticles loading amount and dispersion were analyzed. Nitrogen adsorption isotherms were used to examine surface texture characteristics. The morphology was observed by scanning electron microscopy (MEB) equipped with an energy dispersive spectrometry system (EDS), which was used to determine the amount of deposited Ni. The material with smooth texture (SMT) consists of big agglomerates of semispherical shape particles of 400 nm. Whilst the porous texture (PRT) exhibit a pore-wall formed of needles shape particles of around 200 nm in size. Results indicated that texture characteristics strongly influence the deposition reaction rate; for PRT oxide, Ni deposition can be done from 20 °C while for SMT oxide deposition begins at 40 °C. Analysis of Sr{sub 2}Ta{sub 2}O{sub 7} surface indicated that in both textures, Ni nanoparticles with spherical shape in the range of 10–20 nm were obtained.

Superparamagnetism and coercivity in HCP-Co nanoparticles dispersed in silica matrix

Energy Technology Data Exchange (ETDEWEB)

Julian Fernandez, C. de E-mail: dejulian@padova.infm.it; Mattei, G.; Sangregorio, C.; Battaglin, C.; Gatteschi, D.; Mazzoldi, P

2004-05-01

The magnetic properties of Co HCP nanoparticles dispersed in a silica matrix with sizes between 2{+-}0.7 and 5{+-}2.2 nm were investigated. The temperature dependence of zero-field cooled and field cooled magnetizations and of the coercive field were analyzed considering the thermal activated demagnetization process. Enhanced anisotropy was observed for the 2 nm nanoparticles, while the demagnetization process of the larger ones is dominated by interparticle interactions.

Generation of nanoparticle agglomerates and their dispersion in lung serum simulant or water

International Nuclear Information System (INIS)

Wong, B A; Moss, O R; Nash, D G

2009-01-01

Nanoparticles released into the atmosphere, due to their high diffusivity, will likely begin to agglomerate. The state of agglomeration upon inhalation and the potential to disperse back into nanoparticles may affect the toxicity of the inhaled material. In order to investigate particle dispersion, a system was set up to generate aggregates from agglomerates. Primary particles, composed of zinc, were generated using zinc rods in a spark generator (Palas GFG-1000, Karlsrhue, Germany). These particles formed agglomerates which were passed through a room temperature aging chamber or through a tube furnace (Carbolite HST, Derbyshire, UK). Agglomerate size was measured with a scanning mobility particle sizer (SMPS model 3936, TSI Inc., Shoreview, MN). When furnace temperature was set near the zinc coalescence temperature, instead of decreasing in size, agglomerate size increased up to 30%; a percentage increase duplicated with the room temperature aging chamber. Starting with an aerosol of primary zinc particles, equal concentrations of agglomerate and aggregrate aerosol were produced. The extent of breakup and dispersion of agglomerates and aggregates to individual nanoparticles in lung serum simulant will be assessed using transmission electron microscopy.

Biosynthesis of Metal Nanoparticles: A Review

International Nuclear Information System (INIS)

Kulkarni, N.; Muddapur, U.

2014-01-01

The synthesis of nano structured materials, especially metallic nanoparticles, has accrued utmost interest over the past decade owing to their unique properties that make them applicable in different fields of science and technology. The limitation to the use of these nanoparticles is the paucity of an effective method of synthesis that will produce homogeneous size and shape nanoparticles as well as particles with limited or no toxicity to the human health and the environment. The biological method of nanoparticle synthesis is a relatively simple, cheap, and environmentally friendly method than the conventional chemical method of synthesis and thus gains an upper hand. The bio mineralization of nanoparticles in protein cages is one of such biological approaches used in the generation of nanoparticles. This method of synthesis apart from being a safer method in the production of nanoparticles is also able to control particle morphology.

Biosynthesis of Metal Nanoparticles: A Review

Directory of Open Access Journals (Sweden)

Narendra Kulkarni

2014-01-01

Full Text Available The synthesis of nanostructured materials, especially metallic nanoparticles, has accrued utmost interest over the past decade owing to their unique properties that make them applicable in different fields of science and technology. The limitation to the use of these nanoparticles is the paucity of an effective method of synthesis that will produce homogeneous size and shape nanoparticles as well as particles with limited or no toxicity to the human health and the environment. The biological method of nanoparticle synthesis is a relatively simple, cheap, and environmentally friendly method than the conventional chemical method of synthesis and thus gains an upper hand. The biomineralization of nanoparticles in protein cages is one of such biological approaches used in the generation of nanoparticles. This method of synthesis apart from being a safer method in the production of nanoparticles is also able to control particle morphology.

Quantitation of Surface Coating on Nanoparticles Using Thermogravimetric Analysis.

Science.gov (United States)

Dongargaonkar, Alpana A; Clogston, Jeffrey D

2018-01-01

Nanoparticles are critical components in nanomedicine and nanotherapeutic applications. Some nanoparticles, such as metallic nanoparticles, consist of a surface coating or surface modification to aid in its dispersion and stability. This surface coating may affect the behavior of nanoparticles in a biological environment, thus it is important to measure. Thermogravimetric analysis (TGA) can be used to determine the amount of coating on the surface of the nanoparticle. TGA experiments run under inert atmosphere can also be used to determine residual metal content present in the sample. In this chapter, the TGA technique and experimental method are described.

From nanoparticles to fibres: effect of dispersion composition on fibre properties

Science.gov (United States)

Schirmer, Katharina S. U.; Esrafilzadeh, Dorna; Thompson, Brianna C.; Quigley, Anita F.; Kapsa, Robert M. I.; Wallace, Gordon G.

2015-06-01

A polyvinyl alcohol (PVA)-stabilized polypyrrole nanodispersion has been optimised for conductivity and processability by decreasing the quantity of PVA before and after synthesis. A reduction of PVA before synthesis leads to the formation of particles with a slight increase in dry particle diameter (51 ± 6 to 63 ± 3 nm), and conversely a reduced hydrodynamic diameter. Conductivity of the dried nanoparticle films was not measureable after a reduction of PVA prior to synthesis. Using filtration of particles after synthesis, PVA content was sufficiently reduced to achieve dried thin film conductivity of 2 S cm-1, while the electroactivity of the dispersed particles remained unchanged. The as-synthesized and PVA-reduced polypyrrole particles were successfully spun into all-nanoparticle fibres using a wet-extrusion approach without the addition of any polymer or gel matrix. Using nanoparticles as a starting material is a novel approach, which allowed the production of macro-scale fibres that consisted entirely of polypyrrole nanoparticles. Fibres made from PVA-reduced polypyrrole showed higher electroactivity compared to fibres composed of the dispersion high in PVA. The mechanical properties of the fibres were also improved by reducing the amount of PVA present, resulting in a stronger, more ductile and less brittle fibre, which could find potential application in various fields.

Terahertz pulse generation from metal nanoparticle ink

Science.gov (United States)

Kato, Kosaku; Takano, Keisuke; Tadokoro, Yuzuru; Phan, Thanh Nhat Khoa; Nakajima, Makoto

2016-11-01

Terahertz pulse generation from metallic nanostructures irradiated by femtosecond laser pulses is of interest because the conversion efficiency from laser pulses to terahertz waves is increased by the local field enhancement resulting from the plasmon oscillation. In this talk we present our recent study on terahertz generation from metal nanoparticle ink. We baked a silver nanoparticle ink spin-coated onto a glass coverslip in various temperatures. On the surface of the baked ink, bumpy nanostructures are spontaneously formed, and the average size of bumps depends on the baking temperature. These structures are expected to lead to local field enhancement and then large nonlinear polarizations on the surface. The baked ink was irradiated by the output of regeneratively amplified Ti:sapphire femtosecond laser at an incidence angle of 45°. Waveforms of generated terahertz pulses are detected by electro-optical sampling. The generation efficiency was high when the average diameter of bumps was around 100 nm, which is realized when the ink is baked in 205 to 235°C in our setup. One of our next research targets is terahertz wave generation from micro-patterned metallic nanoparticle ink. It is an advantage of the metal nanoparticle ink that by using inkjet printers one can fabricate various patterns with micrometer scales, in which terahertz waves have a resonance. Combination of microstructures made by a printer and nanostructure spontaneously formed in the baking process will provide us terahertz emitters with unique frequency characteristics.

Polymer Nanocomposite Film with Metal Rich Surface Prepared by In Situ Single-Step Formation of Palladium Nanoparticles: An Interesting Way to Combine Specific Functional Properties

Directory of Open Access Journals (Sweden)

David Thompson

2016-10-01

Full Text Available This paper presents a continuous single-step route that permits preparation of a thermostable polymer/metal nanocomposite film and to combine different functional properties in a unique material. More precisely, palladium nanoparticles are in situ generated in a polyimide matrix thanks to a designed curing cycle which is applied to a polyamic acid/metal precursor solution cast on a glass plate. A metal-rich surface layer which is strongly bonded to the bulk film is formed in addition to homogeneously dispersed metal nanoparticles. This specific morphology leads to obtaining an optically reflective film. The metal nanoparticles act as gas diffusion barriers for helium, oxygen, and carbon dioxide; they induce a tortuosity effect which allows dividing the gas permeation coefficients by a factor near to 2 with respect to the neat polyimide matrix. Moreover, the ability of the in situ synthesized palladium nanoparticles to entrap hydrogen is evidenced. The nanocomposite film properties can be modulated as a function of the location of the film metal-rich surface with respect to the hydrogen feed. The synthesized nanocomposite could represent a major interest for a wide variety of applications, from specific coatings for aerospace or automotive industry, to catalysis applications or sensors.

Dose assessment of SiC nanoparticle dispersions during in vitro assays

International Nuclear Information System (INIS)

Mejia, Jorge; Piret, Jean-Pascal; Noël, Florence; Masereel, Bernard; Toussaint, Olivier; Lucas, Stéphane

2013-01-01

Here, we show that key physicochemical parameters of commercial Silicon Carbide nanoparticles, such as the primary particles of about 53 nm in size, the agglomerates size, and the surface composition, are considerably modified with respect to the pristine conditions, during in vitro assessment. The use of sample conditioning stages, such as the pre-dispersion in aqueous media and the subsequent dispersion in a culture medium specific to the in vitro assay, produce modifications as the absorption of N, C, and O, from the culture medium, in the nanoparticles surface. Our results show that the sedimented dose, fraction of sedimented NPs during incubation and consequently in contact with cells seeded at the bottom, of Silicon Carbide nanoparticles can be measured from the particle size distribution obtained using a centrifugal liquid sedimentation technique. It is underlined that the variations observed in the physicochemical properties are related to the in vitro assay conditions. Culture medium and incubation time are found to influence the most the sedimented dose and consequently the cells dose uptake

Water- and organo-dispersible gold nanoparticles supported by using ammonium salts of hyperbranched polystyrene: preparation and catalysis.

Science.gov (United States)

Gao, Lei; Nishikata, Takashi; Kojima, Keisuke; Chikama, Katsumi; Nagashima, Hideo

2013-12-01

Gold nanoparticles (1 nm in size) stabilized by ammonium salts of hyperbranched polystyrene are prepared. Selection of the R groups provides access to both water- and organo-dispersible gold nanoparticles. The resulting gold nanoparticles are subjected to studies on catalysis in solution, which include reduction of 4-nitrophenol with sodium borohydride, aerobic oxidation of alcohols, and homocoupling of phenylboronic acid. In the reduction of 4-nitrophenol, the catalytic activity is clearly dependent on the size of the gold nanoparticles. For the aerobic oxidation of alcohols, two types of biphasic oxidation are achieved: one is the catalyst dispersing in the aqueous phase, whereas the other is in the organic phase. The catalysts are reusable more than four times without loss of the catalytic activity. Selective synthesis of biphenyl is achieved by the homocoupling of phenylboronic acid catalyzed by organo-dispersible gold nanoparticles. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Size-selective separation of polydisperse gold nanoparticles in supercritical ethane.

Science.gov (United States)

Williams, Dylan P; Satherley, John

2009-04-09

The aim of this study was to use supercritical ethane to selectively disperse alkanethiol-stabilized gold nanoparticles of one size from a polydisperse sample in order to recover a monodisperse fraction of the nanoparticles. A disperse sample of metal nanoparticles with diameters in the range of 1-5 nm was prepared using established techniques then further purified by Soxhlet extraction. The purified sample was subjected to supercritical ethane at a temperature of 318 K in the pressure range 50-276 bar. Particles were characterized by UV-vis absorption spectroscopy, TEM, and MALDI-TOF mass spectroscopy. The results show that with increasing pressure the dispersibility of the nanoparticles increases, this effect is most pronounced for smaller nanoparticles. At the highest pressure investigated a sample of the particles was effectively stripped of all the smaller particles leaving a monodisperse sample. The relationship between dispersibility and supercritical fluid density for two different size samples of alkanethiol-stabilized gold nanoparticles was considered using the Chrastil chemical equilibrium model.

Superparamagnetism and coercivity in HCP-Co nanoparticles dispersed in silica matrix

International Nuclear Information System (INIS)

Julian Fernandez, C. de; Mattei, G.; Sangregorio, C.; Battaglin, C.; Gatteschi, D.; Mazzoldi, P.

2004-01-01

The magnetic properties of Co HCP nanoparticles dispersed in a silica matrix with sizes between 2±0.7 and 5±2.2 nm were investigated. The temperature dependence of zero-field cooled and field cooled magnetizations and of the coercive field were analyzed considering the thermal activated demagnetization process. Enhanced anisotropy was observed for the 2 nm nanoparticles, while the demagnetization process of the larger ones is dominated by interparticle interactions

A general method to incorporate metal nanoparticles in zeolites and zeotypes

DEFF Research Database (Denmark)

2015-01-01

Disclosed herein is a method for producing a zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure.......Disclosed herein is a method for producing a zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure....

Computer Optimization of Biodegradable Nanoparticles Fabricated by Dispersion Polymerization

Directory of Open Access Journals (Sweden)

Emmanuel O. Akala

2015-12-01

Full Text Available Quality by design (QbD in the pharmaceutical industry involves designing and developing drug formulations and manufacturing processes which ensure predefined drug product specifications. QbD helps to understand how process and formulation variables affect product characteristics and subsequent optimization of these variables vis-à-vis final specifications. Statistical design of experiments (DoE identifies important parameters in a pharmaceutical dosage form design followed by optimizing the parameters with respect to certain specifications. DoE establishes in mathematical form the relationships between critical process parameters together with critical material attributes and critical quality attributes. We focused on the fabrication of biodegradable nanoparticles by dispersion polymerization. Aided by a statistical software, d-optimal mixture design was used to vary the components (crosslinker, initiator, stabilizer, and macromonomers to obtain twenty nanoparticle formulations (PLLA-based nanoparticles and thirty formulations (poly-ɛ-caprolactone-based nanoparticles. Scheffe polynomial models were generated to predict particle size (nm, zeta potential, and yield (% as functions of the composition of the formulations. Simultaneous optimizations were carried out on the response variables. Solutions were returned from simultaneous optimization of the response variables for component combinations to (1 minimize nanoparticle size; (2 maximize the surface negative zeta potential; and (3 maximize percent yield to make the nanoparticle fabrication an economic proposition.

Magnetic, Fluorescence and Transition Metal Ion Response Properties of 2,6-Diaminopyridine Modified Silica-Coated Fe3O4 Nanoparticles

Directory of Open Access Journals (Sweden)

Yunhui Zhai

2016-08-01

Full Text Available Multi-functional nanoparticles possessing magnetic, fluorescence and transition metal ion response properties were prepared and characterized. The particles have a core/shell structure that consists of silica-coated magnetic Fe3O4 and 2,6-diaminopyridine anchored on the silica surface via organic linker molecules. The resultant nanoparticles were found by transmission electron microscopy to be well-dispersed spherical particles with an average diameter of 10–12 nm. X-ray diffraction analysis suggested the existence of Fe3O4 and silica in/on the particle. Fourier transform infrared spectra revealed that 2,6-diaminopyridine molecules were successfully covalently bonded to the surface of magnetic composite nanoparticles. The prepared particles possessed an emission peak at 364 nm with an excitation wavelength of 307 nm and have a strong reversible response property for some transition metal ions such as Cu2+ and Zn2+. This new material holds considerable promise in selective magneto separation and optical determination applications.

An overview of experimental results and dispersion modelling of nanoparticles in the wake of moving vehicles.

Science.gov (United States)

Carpentieri, Matteo; Kumar, Prashant; Robins, Alan

2011-03-01

Understanding the transformation of nanoparticles emitted from vehicles is essential for developing appropriate methods for treating fine scale particle dynamics in dispersion models. This article provides an overview of significant research work relevant to modelling the dispersion of pollutants, especially nanoparticles, in the wake of vehicles. Literature on vehicle wakes and nanoparticle dispersion is reviewed, taking into account field measurements, wind tunnel experiments and mathematical approaches. Field measurements and modelling studies highlighted the very short time scales associated with nanoparticle transformations in the first stages after the emission. These transformations strongly interact with the flow and turbulence fields immediately behind the vehicle, hence the need of characterising in detail the mixing processes in the vehicle wake. Very few studies have analysed this interaction and more research is needed to build a basis for model development. A possible approach is proposed and areas of further investigation identified. Copyright © 2010 Elsevier Ltd. All rights reserved.

Effects of metallic nanoparticle doped flux on the interfacial intermetallic compounds between lead-free solder ball and copper substrate

International Nuclear Information System (INIS)

Sujan, G.K.; Haseeb, A.S.M.A.; Afifi, A.B.M.

2014-01-01

Lead free solders currently in use are prone to develop thick interfacial intermetallic compound layers with rough morphology which are detrimental to the long term solder joint reliability. A novel method has been developed to control the morphology and growth of intermetallic compound layers between lead-free Sn–3.0Ag–0.5Cu solder ball and copper substrate by doping a water soluble flux with metallic nanoparticles. Four types of metallic nanoparticles (nickel, cobalt, molybdenum and titanium) were used to investigate their effects on the wetting behavior and interfacial microstructural evaluations after reflow. Nanoparticles were dispersed manually with a water soluble flux and the resulting nanoparticle doped flux was placed on copper substrate. Lead-free Sn–3.0Ag–0.5Cu solder balls of diameter 0.45 mm were placed on top of the flux and were reflowed at a peak temperature of 240 °C for 45 s. Angle of contact, wetting area and interfacial microstructure were studied by optical microscopy, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. It was observed that the angle of contact increased and wetting area decreased with the addition of cobalt, molybdenum and titanium nanoparticles to flux. On the other hand, wettability improved with the addition of nickel nanoparticles. Cross-sectional micrographs revealed that both nickel and cobalt nanoparticle doping transformed the morphology of Cu 6 Sn 5 from a typical scallop type to a planer one and reduced the intermetallic compound thickness under optimum condition. These effects were suggested to be related to in-situ interfacial alloying at the interface during reflow. The minimum amount of nanoparticles required to produce the planer morphology was found to be 0.1 wt.% for both nickel and cobalt. Molybdenum and titanium nanoparticles neither appear to undergo alloying during reflow nor have any influence at the solder/substrate interfacial reaction. Thus, doping of flux

Effects of metallic nanoparticle doped flux on the interfacial intermetallic compounds between lead-free solder ball and copper substrate

Energy Technology Data Exchange (ETDEWEB)

Sujan, G.K., E-mail: sgkumer@gmail.com; Haseeb, A.S.M.A., E-mail: haseeb@um.edu.my; Afifi, A.B.M., E-mail: amalina@um.edu.my

2014-11-15

Lead free solders currently in use are prone to develop thick interfacial intermetallic compound layers with rough morphology which are detrimental to the long term solder joint reliability. A novel method has been developed to control the morphology and growth of intermetallic compound layers between lead-free Sn–3.0Ag–0.5Cu solder ball and copper substrate by doping a water soluble flux with metallic nanoparticles. Four types of metallic nanoparticles (nickel, cobalt, molybdenum and titanium) were used to investigate their effects on the wetting behavior and interfacial microstructural evaluations after reflow. Nanoparticles were dispersed manually with a water soluble flux and the resulting nanoparticle doped flux was placed on copper substrate. Lead-free Sn–3.0Ag–0.5Cu solder balls of diameter 0.45 mm were placed on top of the flux and were reflowed at a peak temperature of 240 °C for 45 s. Angle of contact, wetting area and interfacial microstructure were studied by optical microscopy, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. It was observed that the angle of contact increased and wetting area decreased with the addition of cobalt, molybdenum and titanium nanoparticles to flux. On the other hand, wettability improved with the addition of nickel nanoparticles. Cross-sectional micrographs revealed that both nickel and cobalt nanoparticle doping transformed the morphology of Cu{sub 6}Sn{sub 5} from a typical scallop type to a planer one and reduced the intermetallic compound thickness under optimum condition. These effects were suggested to be related to in-situ interfacial alloying at the interface during reflow. The minimum amount of nanoparticles required to produce the planer morphology was found to be 0.1 wt.% for both nickel and cobalt. Molybdenum and titanium nanoparticles neither appear to undergo alloying during reflow nor have any influence at the solder/substrate interfacial reaction. Thus, doping

Investigation of Monodisperse Dendrimeric Polysaccharide Nanoparticle Dispersions Using Small Angle Neutron Scattering

Science.gov (United States)

Atkinson, John; Nickels, Jonathan; Papp-Szabo, Erzsi; Katsaras, John; Dutcher, John

2015-03-01

Phytoglycogen is a highly branched polysaccharide that is very similar to the energy storage molecule glycogen. We have isolated monodisperse phytoglycogen nanoparticles from corn and these particles are attractive for applications in the cosmetic, food and beverage, and biomedical industries. Many of these promising applications are due to the special interaction between the nanoparticles and water, which results in: (1) high solubility; (2) low viscosity and high stability in aqueous dispersions; and (3) a remarkable capacity to sequester and retain water. Our rheology measurements indicate that the nanoparticles behave like hard spheres in water, with the viscosity diverging for concentrations >25% (w/w). Because of this, aqueous suspensions of phytoglycogen provide an ideal platform for detailed testing of theories of colloidal glasses and jamming. To further explore the interaction of the phytoglycogen particles and water, we have performed small angle neutron scattering (SANS) measurements on the Extended Q-Range SANS (EQ-SANS) diffractometer at the Spallation Neutron Source at Oak Ridge National Laboratory. Measurements performed on phytoglycogen dispersions in mixtures of hydrogenated and deuterated water have allowed us to determine the particle size and average particle spacing as a function of the phytoglycogen concentration in the limits of dilute and concentrated dispersions.

Enhancement of light absorption in polyazomethines due to plasmon excitation on randomly distributed metal nanoparticles

Science.gov (United States)

Wróbel, P.; Antosiewicz, T. J.; Stefaniuk, T.; Ciesielski, A.; Iwan, A.; Wronkowska, A. A.; Wronkowski, A.; Szoplik, T.

2015-05-01

In photovoltaic devices, metal nanoparticles embedded in a semiconductor layer allow the enhancement of solar-toelectric energy conversion efficiency due to enhanced light absorption via a prolonged optical path, enhanced electric fields near the metallic inclusions, direct injection of hot electrons, or local heating. Here we pursue the first two avenues. In the first, light scattered at an angle beyond the critical angle for reflection is coupled into the semiconductor layer and confined within such planar waveguide up to possible exciton generation. In the second, light is trapped by the excitation of localized surface plasmons on metal nanoparticles leading to enhanced near-field plasmon-exciton coupling at the peak of the plasmon resonance. We report on results of a numerical experiment on light absorption in polymer- (fullerene derivative) blends, using the 3D FDTD method, where exact optical parameters of the materials involved are taken from our recent measurements. In simulations we investigate light absorption in randomly distributed metal nanoparticles dispersed in polyazomethine-(fullerene derivative) blends, which serve as active layers in bulkheterojunction polymer solar cells. In the study Ag and Al nanoparticles of different diameters and fill factors are diffused in two air-stable aromatic polyazomethines with different chemical structures (abbreviated S9POF and S15POF) mixed with phenyl-C61-butyric acid methyl ester (PCBM) or [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). The mixtures are spin coated on a 100 nm thick Al layer deposited on a fused silica substrate. Optical constants of the active layers are taken from spectroscopic ellipsometry and reflectance measurements using a rotating analyzer type ellipsometer with auto-retarder performed in the wavelength range from 225 nm to 2200 nm. The permittivities of Ag and Al particles of diameters from 20 to 60 nm are assumed to be equal to those measured on 100 to 200 nm thick metal films.

Localized Plasmon resonance in metal nanoparticles using Mie theory

Science.gov (United States)

Duque, J. S.; Blandón, J. S.; Riascos, H.

2017-06-01

In this work, scattering light by colloidal metal nanoparticles with spherical shape was studied. Optical properties such as diffusion efficiencies of extinction and absorption Q ext and Q abs were calculated using Mie theory. We employed a MATLAB program to calculate the Mie efficiencies and the radial dependence of electric field intensities emitted for colloidal metal nanoparticles (MNPs). By UV-Vis spectroscopy we have determined the LSPR for Cu nanoparticles (CuNPs), Ni nanoparticles (NiNPs) and Co nanoparticles (CoNPs) grown by laser ablation technique. The peaks of resonances appear in 590nm, 384nm and 350nm for CuNPs, NiNPs and CoNPs respectively suspended in water. Changing the medium to acetone and ethanol we observed a shift of the resonance peaks, these values agreed with our simulations results.

Potential application of metal nanoparticles for dosimetric systems: Concepts and perspectives

Energy Technology Data Exchange (ETDEWEB)

Guidelli, Eder José, E-mail: ederguidelli@pg.ffclrp.usp.br; Baffa, Oswaldo, E-mail: ederguidelli@pg.ffclrp.usp.br [Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirão Preto, SP (Brazil)

2014-11-07

Metallic nanoparticles increase the delivered dose and consequently enhance tissue radio sensitization during radiation therapy of cancer. The Dose Enhancement Factor (DEF) corresponds to the ratio between the dose deposited on a tissue containing nanoparticles, and the dose deposited on a tissue without nanoparticles. In this sense, we have used electron spin resonance spectroscopy (ESR) to investigate how silver and gold nanoparticles affect the dose deposition in alanine dosimeters, which act as a surrogate of soft tissue. Besides optimizing radiation absorption by the dosimeter, the optical properties of these metal nanoparticles could also improve light emission from materials employed as radiation detectors. Therefore, we have also examined how the plasmonic properties of noble metal nanoparticles could enhance radiation detection using optically stimulated luminescence (OSL) dosimetry. This work will show results on how the use of gold and silver nanoparticles are beneficial for the ESR and OSL dosimetric techniques, and will describe the difficulties we have been facing, the challenges to overcome, and the perspectives.

Characteristic of the Nanoparticles Formed on the Carbon Steel Surface Contacting with 3d-Metal Water Salt Solutions in the Open-Air System

Science.gov (United States)

Lavrynenko, O. M.; Pavlenko, O. Yu; Shchukin, Yu S.

2016-02-01

The contact of a steel electrode with water dispersion medium in an open-air system leads to the development of various polymorphic iron oxides and oxyhydroxides on the steel surface. Whereas the usage of distilled water causes the obtaining of Fe(II)-Fe(III) layered double hydroxides (green rust) as a primary mineral phase, but in the presence of inorganic 3d-metal water salt solutions, mixed layered double hydroxides (LDHs) together with non-stoichiometric spinel ferrite nanoparticles are formed on the steel surface. Mixed LDHs keep stability against further oxidation and complicate the obtaining of spinel ferrite nanoparticles. Thermal treatment of mixed LDHs among other mineral phases formed via the rotation-corrosion dispergation process at certain temperatures permits to obtain homogenous nanoparticles of spinel ferrites as well as maghemite or hematite doped by 3d-metal cations.

Multiscale study of metal nanoparticles

Science.gov (United States)

Lee, Byeongchan

Extremely small structures with reduced dimensionality have emerged as a scientific motif for their interesting properties. In particular, metal nanoparticles have been identified as a fundamental material in many catalytic activities; as a consequence, a better understanding of structure-function relationship of nanoparticles has become crucial. The functional analysis of nanoparticles, reactivity for example, requires an accurate method at the electronic structure level, whereas the structural analysis to find energetically stable local minima is beyond the scope of quantum mechanical methods as the computational cost becomes prohibitingly high. The challenge is that the inherent length scale and accuracy associated with any single method hardly covers the broad scale range spanned by both structural and functional analyses. In order to address this, and effectively explore the energetics and reactivity of metal nanoparticles, a hierarchical multiscale modeling is developed, where methodologies of different length scales, i.e. first principles density functional theory, atomistic calculations, and continuum modeling, are utilized in a sequential fashion. This work has focused on identifying the essential information that bridges two different methods so that a successive use of different methods is seamless. The bond characteristics of low coordination systems have been obtained with first principles calculations, and incorporated into the atomistic simulation. This also rectifies the deficiency of conventional interatomic potentials fitted to bulk properties, and improves the accuracy of atomistic calculations for nanoparticles. For the systematic shape selection of nanoparticles, we have improved the Wulff-type construction using a semi-continuum approach, in which atomistic surface energetics and crystallinity of materials are added on to the continuum framework. The developed multiscale modeling scheme is applied to the rational design of platinum

Electroluminescence Efficiency Enhancement using Metal Nanoparticles

National Research Council Canada - National Science Library

Soref, Richard A; Khurgin, J. B; Sun, G

2008-01-01

We apply the "effective mode volume" theory to evaluate enhancement of the electroluminescence efficiency of semiconductor emitters placed in the vicinity of isolated metal nanoparticles and their arrays...

Multimodal Dispersion of Nanoparticles: A Comprehensive Evaluation of Size Distribution with 9 Size Measurement Methods.

Science.gov (United States)

Varenne, Fanny; Makky, Ali; Gaucher-Delmas, Mireille; Violleau, Frédéric; Vauthier, Christine

2016-05-01

Evaluation of particle size distribution (PSD) of multimodal dispersion of nanoparticles is a difficult task due to inherent limitations of size measurement methods. The present work reports the evaluation of PSD of a dispersion of poly(isobutylcyanoacrylate) nanoparticles decorated with dextran known as multimodal and developed as nanomedecine. The nine methods used were classified as batch particle i.e. Static Light Scattering (SLS) and Dynamic Light Scattering (DLS), single particle i.e. Electron Microscopy (EM), Atomic Force Microscopy (AFM), Tunable Resistive Pulse Sensing (TRPS) and Nanoparticle Tracking Analysis (NTA) and separative particle i.e. Asymmetrical Flow Field-Flow Fractionation coupled with DLS (AsFlFFF) size measurement methods. The multimodal dispersion was identified using AFM, TRPS and NTA and results were consistent with those provided with the method based on a separation step prior to on-line size measurements. None of the light scattering batch methods could reveal the complexity of the PSD of the dispersion. Difference between PSD obtained from all size measurement methods tested suggested that study of the PSD of multimodal dispersion required to analyze samples by at least one of the single size particle measurement method or a method that uses a separation step prior PSD measurement.

Pure and multi metal oxide nanoparticles: synthesis, antibacterial and cytotoxic properties.

Science.gov (United States)

Stankic, Slavica; Suman, Sneha; Haque, Francia; Vidic, Jasmina

2016-10-24

Th antibacterial activity of metal oxide nanoparticles has received marked global attention as they can be specifically synthesized to exhibit significant toxicity to bacteria. The importance of their application as antibacterial agents is evident keeping in mind the limited range and effectiveness of antibiotics, on one hand, and the plethora of metal oxides, on the other, along with the propensity of nanoparticles to induce resistance being much lower than that of antibiotics. Effective inhibition against a wide range of bacteria is well known for several nano oxides consisting of one metal (Fe 3 O 4 , TiO 2 , CuO, ZnO), whereas, research in the field of multi-metal oxides still demands extensive exploration. This is understandable given that the relationship between physicochemical properties and biological activity seems to be complex and difficult to generalize even for metal oxide nanoparticles consisting of only one metal component. Also, despite the broad scope that metal oxide nanoparticles have as antibacterial agents, there arise problems in practical applications taking into account the cytotoxic effects. In this respect, the consideration of polymetallic oxides for biological applications becomes even greater since these can provide synergetic effects and unify the best physicochemical properties of their components. For instance, strong antibacterial efficiency specific of one metal oxide can be complemented by non-cytotoxicity of another. This review presents the main methods and technological advances in fabrication of nanostructured metal oxides with a particular emphasis to multi-metal oxide nanoparticles, their antibacterial effects and cytotoxicity.

Pure and multi metal oxide nanoparticles: synthesis, antibacterial and cytotoxic properties

Directory of Open Access Journals (Sweden)

Slavica Stankic

2016-10-01

Full Text Available Abstract Th antibacterial activity of metal oxide nanoparticles has received marked global attention as they can be specifically synthesized to exhibit significant toxicity to bacteria. The importance of their application as antibacterial agents is evident keeping in mind the limited range and effectiveness of antibiotics, on one hand, and the plethora of metal oxides, on the other, along with the propensity of nanoparticles to induce resistance being much lower than that of antibiotics. Effective inhibition against a wide range of bacteria is well known for several nano oxides consisting of one metal (Fe3O4, TiO2, CuO, ZnO, whereas, research in the field of multi-metal oxides still demands extensive exploration. This is understandable given that the relationship between physicochemical properties and biological activity seems to be complex and difficult to generalize even for metal oxide nanoparticles consisting of only one metal component. Also, despite the broad scope that metal oxide nanoparticles have as antibacterial agents, there arise problems in practical applications taking into account the cytotoxic effects. In this respect, the consideration of polymetallic oxides for biological applications becomes even greater since these can provide synergetic effects and unify the best physicochemical properties of their components. For instance, strong antibacterial efficiency specific of one metal oxide can be complemented by non-cytotoxicity of another. This review presents the main methods and technological advances in fabrication of nanostructured metal oxides with a particular emphasis to multi-metal oxide nanoparticles, their antibacterial effects and cytotoxicity.

Comparison of properties of silver-metal oxide electrical contact materials

Directory of Open Access Journals (Sweden)

Ćosović V.

2012-01-01

Full Text Available Changes in physical properties such as density, porosity, hardness and electrical conductivity of the Ag-SnO2 and Ag-SnO2In2O3 electrical contact materials induced by introduction of metal oxide nanoparticles were investigated. Properties of the obtained silver-metal oxide nanoparticle composites are discussed and presented in comparison to their counterparts with the micro metal oxide particles as well as comparable Ag-SnO2WO3 and Ag-ZnO contact materials. Studied silvermetal oxide composites were produced by powder metallurgy method from very fine pure silver and micro- and nanoparticle metal oxide powders. Very uniform microstructures were obtained for all investigated composites and they exhibited physical properties that are comparable with relevant properties of equivalent commercial silver based electrical contact materials. Both Ag-SnO2 and Ag- SnO2In2O3 composites with metal oxide nanoparticles were found to have lower porosity, higher density and hardness than their respective counterparts which can be attributed to better dispersion hardening i.e. higher degree of dispersion of metal oxide in silver matrix.

Mass production of polymer nano-wires filled with metal nano-particles.

Science.gov (United States)

Lomadze, Nino; Kopyshev, Alexey; Bargheer, Matias; Wollgarten, Markus; Santer, Svetlana

2017-08-17

Despite the ongoing progress in nanotechnology and its applications, the development of strategies for connecting nano-scale systems to micro- or macroscale elements is hampered by the lack of structural components that have both, nano- and macroscale dimensions. The production of nano-scale wires with macroscale length is one of the most interesting challenges here. There are a lot of strategies to fabricate long nanoscopic stripes made of metals, polymers or ceramics but none is suitable for mass production of ordered and dense arrangements of wires at large numbers. In this paper, we report on a technique for producing arrays of ordered, flexible and free-standing polymer nano-wires filled with different types of nano-particles. The process utilizes the strong response of photosensitive polymer brushes to irradiation with UV-interference patterns, resulting in a substantial mass redistribution of the polymer material along with local rupturing of polymer chains. The chains can wind up in wires of nano-scale thickness and a length of up to several centimeters. When dispersing nano-particles within the film, the final arrangement is similar to a core-shell geometry with mainly nano-particles found in the core region and the polymer forming a dielectric jacket.

From nanoparticles to fibres: effect of dispersion composition on fibre properties

Energy Technology Data Exchange (ETDEWEB)

Schirmer, Katharina S. U.; Esrafilzadeh, Dorna; Thompson, Brianna C.; Quigley, Anita F.; Kapsa, Robert M. I.; Wallace, Gordon G., E-mail: gwallace@uow.edu.au [University of Wollongong, ARC Centre for Electromaterials Science and Intelligent Polymer Research Institute (Australia)

2015-06-15

A polyvinyl alcohol (PVA)-stabilized polypyrrole nanodispersion has been optimised for conductivity and processability by decreasing the quantity of PVA before and after synthesis. A reduction of PVA before synthesis leads to the formation of particles with a slight increase in dry particle diameter (51 ± 6 to 63 ± 3 nm), and conversely a reduced hydrodynamic diameter. Conductivity of the dried nanoparticle films was not measureable after a reduction of PVA prior to synthesis. Using filtration of particles after synthesis, PVA content was sufficiently reduced to achieve dried thin film conductivity of 2 S cm{sup −1}, while the electroactivity of the dispersed particles remained unchanged. The as-synthesized and PVA-reduced polypyrrole particles were successfully spun into all-nanoparticle fibres using a wet-extrusion approach without the addition of any polymer or gel matrix. Using nanoparticles as a starting material is a novel approach, which allowed the production of macro-scale fibres that consisted entirely of polypyrrole nanoparticles. Fibres made from PVA-reduced polypyrrole showed higher electroactivity compared to fibres composed of the dispersion high in PVA. The mechanical properties of the fibres were also improved by reducing the amount of PVA present, resulting in a stronger, more ductile and less brittle fibre, which could find potential application in various fields.

From nanoparticles to fibres: effect of dispersion composition on fibre properties

International Nuclear Information System (INIS)

Schirmer, Katharina S. U.; Esrafilzadeh, Dorna; Thompson, Brianna C.; Quigley, Anita F.; Kapsa, Robert M. I.; Wallace, Gordon G.

2015-01-01

A polyvinyl alcohol (PVA)-stabilized polypyrrole nanodispersion has been optimised for conductivity and processability by decreasing the quantity of PVA before and after synthesis. A reduction of PVA before synthesis leads to the formation of particles with a slight increase in dry particle diameter (51 ± 6 to 63 ± 3 nm), and conversely a reduced hydrodynamic diameter. Conductivity of the dried nanoparticle films was not measureable after a reduction of PVA prior to synthesis. Using filtration of particles after synthesis, PVA content was sufficiently reduced to achieve dried thin film conductivity of 2 S cm −1 , while the electroactivity of the dispersed particles remained unchanged. The as-synthesized and PVA-reduced polypyrrole particles were successfully spun into all-nanoparticle fibres using a wet-extrusion approach without the addition of any polymer or gel matrix. Using nanoparticles as a starting material is a novel approach, which allowed the production of macro-scale fibres that consisted entirely of polypyrrole nanoparticles. Fibres made from PVA-reduced polypyrrole showed higher electroactivity compared to fibres composed of the dispersion high in PVA. The mechanical properties of the fibres were also improved by reducing the amount of PVA present, resulting in a stronger, more ductile and less brittle fibre, which could find potential application in various fields

Surface modification of zinc oxide nanoparticle by PMAA and its dispersion in aqueous system

Energy Technology Data Exchange (ETDEWEB)

Tang Erjun [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); School of Chemical and Pharmaceutical Engineering, Hebei University of Science and Technology, Shijiazhuang Hebei 050018 (China); Cheng Guoxiang [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China)]. E-mail: gxcheng@tju.edu.cn; Ma Xiaolu [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Pang Xingshou [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Zhao Qiang [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China)

2006-05-15

Commercial zinc oxide nanoparticles were modified by polymethacrylic acid (PMAA) in aqueous system. The hydroxyl groups of nano-ZnO particle surface can interact with carboxyl groups (COO-) of PMAA and form poly(zinc methacrylate) complex on the surface of nano-ZnO. The formation of poly(zinc methacrylate) complex was testified by Fourier-transform infrared spectra (FT-IR). Thermogravimetric analysis (TGA) indicated that PMAA molecules were absorbed or anchored on the surface of nano-ZnO particle, which facilitated to hinder the aggregation of nano-ZnO particles. Through particle size analysis and transmission electron micrograph (TEM) observation, it was found that PMAA enhanced the dispersibility of nano-ZnO particles in water. The dispersion stabilization of modified ZnO nanoparticles in aqueous system was significantly improved due to the introduction of grafted polymer on the surface of nanoparticles. The modification did not alter the crystalline structure of the ZnO nanoparticles according to the X-ray diffraction patterns.

Surface modification of zinc oxide nanoparticle by PMAA and its dispersion in aqueous system

Science.gov (United States)

Tang, Erjun; Cheng, Guoxiang; Ma, Xiaolu; Pang, Xingshou; Zhao, Qiang

2006-05-01

Commercial zinc oxide nanoparticles were modified by polymethacrylic acid (PMAA) in aqueous system. The hydroxyl groups of nano-ZnO particle surface can interact with carboxyl groups (COO-) of PMAA and form poly(zinc methacrylate) complex on the surface of nano-ZnO. The formation of poly(zinc methacrylate) complex was testified by Fourier-transform infrared spectra (FT-IR). Thermogravimetric analysis (TGA) indicated that PMAA molecules were absorbed or anchored on the surface of nano-ZnO particle, which facilitated to hinder the aggregation of nano-ZnO particles. Through particle size analysis and transmission electron micrograph (TEM) observation, it was found that PMAA enhanced the dispersibility of nano-ZnO particles in water. The dispersion stabilization of modified ZnO nanoparticles in aqueous system was significantly improved due to the introduction of grafted polymer on the surface of nanoparticles. The modification did not alter the crystalline structure of the ZnO nanoparticles according to the X-ray diffraction patterns.

Gold nanoparticles modified with coordination compounds of metals: synthesis and application

International Nuclear Information System (INIS)

Beloglazkina, Elena K; Majouga, Alexander G; Romashkina, Renata B; Zyk, Nikolai V; Zefirov, Nikolai S

2012-01-01

The data on the preparation methods and applications of gold nanoparticles with coordinated metal ions on the surfaces are generalized. The currently available data on the interaction of metal ions with gold nanoparticles modified with organic (particularly, sulfur-containing) ligands comprising terminal chelating groups are considered in detail as well as the applications of such modified nanoparticles. The bibliography includes 141 references.

Biocompatible Metal-Oxide Nanoparticles: Nanotechnology Improvement of Conventional Prosthetic Acrylic Resins

Directory of Open Access Journals (Sweden)

Laura S. Acosta-Torres

2011-01-01

Full Text Available Nowadays, most products for dental restoration are produced from acrylic resins based on heat-cured Poly(Methyl MethAcrylate (PMMA. The addition of metal nanoparticles to organic materials is known to increase the surface hydrophobicity and to reduce adherence to biomolecules. This paper describes the use of nanostructured materials, TiO2 and Fe2O3, for simultaneously coloring and/or improving the antimicrobial properties of PMMA resins. Nanoparticles of metal oxides were included during suspension polymerization to produce hybrid metal oxides-alginate-containing PMMA. Metal oxide nanoparticles were characterized by dynamic light scattering, and X-ray diffraction. Physicochemical characterization of synthesized resins was assessed by a combination of spectroscopy, scanning electron microscopy, viscometry, porosity, and mechanical tests. Adherence of Candida albicans cells and cellular compatibility assays were performed to explore biocompatibility and microbial adhesion of standard and novel materials. Our results show that introduction of biocompatible metal nanoparticles is a suitable means for the improvement of conventional acrylic dental resins.

Biocompatible Metal-Oxide Nanoparticles: Nanotechnology Improvement of Conventional Prosthetic Acrylic Resins

International Nuclear Information System (INIS)

Acosta-Torres, L.S.; Lopez-Marin, L.M.; Padron, G.H.; Castano, V.M.; Nunez-Anita, R.E.

2011-01-01

Nowadays, most products for dental restoration are produced from acrylic resins based on heat-cured Poly(Methyl Methacrylate) (PMMA). The addition of metal nanoparticles to organic materials is known to increase the surface hydrophobicity and to reduce adherence to biomolecules. This paper describes the use of nano structured materials, TiO 2 and Fe 2 O 3 , for simultaneously coloring and/or improving the antimicrobial properties of PMMA resins. Nanoparticles of metal oxides were included during suspension polymerization to produce hybrid metal oxides-alginate-containing PMMA. Metal oxide nanoparticles were characterized by dynamic light scattering, and X-ray diffraction. Physicochemical characterization of synthesized resins was assessed by a combination of spectroscopy, scanning electron microscopy, viscometry, porosity, and mechanical tests. Adherence of Candida albicans cells and cellular compatibility assays were performed to explore biocompatibility and microbial adhesion of standard and novel materials. Our results show that introduction of biocompatible metal nanoparticles is a suitable means for the improvement of conventional acrylic dental resins.

Biotests and Biosensors for Ecotoxicology of Metal Oxide Nanoparticles: A Minireview

Directory of Open Access Journals (Sweden)

Kaja Kasemets

2008-08-01

Full Text Available Nanotechnologies have become a significant priority worldwide. Several manufactured nanoparticles - particles with one dimension less than 100 nm - are increasingly used in consumer products. At nanosize range, the properties of materials differ substantially from bulk materials of the same composition, mostly due to the increased specific surface area and reactivity, which may lead to increased bioavailability and toxicity. Thus, for the assessment of sustainability of nanotechnologies, hazards of manufactured nanoparticles have to be studied. Despite all the above mentioned, the data on the potential environmental effects of nanoparticles are rare. This mini-review is summarizing the emerging information on different aspects of ecotoxicological hazard of metal oxide nanoparticles, focusing on TiO2, ZnO and CuO. Various biotests that have been successfully used for evaluation of ecotoxic properties of pollutants to invertebrates, algae and bacteria and now increasingly applied for evaluation of hazard of nanoparticles at different levels of the aquatic food-web are discussed. Knowing the benefits and potential drawbacks of these systems, a suite of tests for evaluation of environmental hazard of nanoparticles is proposed. Special attention is paid to the influence of particle solubility and to recombinant metal-sensing bacteria as powerful tools for quantification of metal bioavailability. Using recombinant metal-specific bacterial biosensors and multitrophic ecotoxicity assays in tandem will create new scientific knowledge on the respective role of ionic species and of particles in toxicity of metal oxide nanoparticles.

Highly stable noble-metal nanoparticles in tetraalkylphosphonium ionic liquids for in situ catalysis.

Science.gov (United States)

Banerjee, Abhinandan; Theron, Robin; Scott, Robert W J

2012-01-09

Gold and palladium nanoparticles were prepared by lithium borohydride reduction of the metal salt precursors in tetraalkylphosphonium halide ionic liquids in the absence of any organic solvents or external nanoparticle stabilizers. These colloidal suspensions remained stable and showed no nanoparticle agglomeration over many months. A combination of electrostatic interactions between the coordinatively unsaturated metal nanoparticle surface and the ionic-liquid anions, bolstered by steric protection offered by the bulky alkylated phosphonium cations, is likely to be the reason behind such stabilization. The halide anion strongly absorbs to the nanoparticle surface, leading to exceptional nanoparticle stability in halide ionic liquids; other tetraalkylphosphonium ionic liquids with non-coordinating anions, such as tosylate and hexafluorophosphate, show considerably lower affinities towards the stabilization of nanoparticles. Palladium nanoparticles stabilized in the tetraalkylphosphonium halide ionic liquid were stable, efficient, and recyclable catalysts for a variety of hydrogenation reactions at ambient pressures with sustained activity. Aerial oxidation of the metal nanoparticles occurred over time and was readily reversed by re-reduction of oxidized metal salts. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Method for forming thermally stable nanoparticles on supports

Science.gov (United States)

Roldan Cuenya, Beatriz; Naitabdi, Ahmed R.; Behafarid, Farzad

2013-08-20

An inverse micelle-based method for forming nanoparticles on supports includes dissolving a polymeric material in a solvent to provide a micelle solution. A nanoparticle source is dissolved in the micelle solution. A plurality of micelles having a nanoparticle in their core and an outer polymeric coating layer are formed in the micelle solution. The micelles are applied to a support. The polymeric coating layer is then removed from the micelles to expose the nanoparticles. A supported catalyst includes a nanocrystalline powder, thin film, or single crystal support. Metal nanoparticles having a median size from 0.5 nm to 25 nm, a size distribution having a standard deviation .ltoreq.0.1 of their median size are on or embedded in the support. The plurality of metal nanoparticles are dispersed and in a periodic arrangement. The metal nanoparticles maintain their periodic arrangement and size distribution following heat treatments of at least 1,000.degree. C.

Electrochemistry of conductive polymers 39. Contacts between conducting polymers and noble metal nanoparticles studied by current-sensing atomic force microscopy.

Science.gov (United States)

Cho, Shin Hyo; Park, Su-Moon

2006-12-28

Electrical properties of contacts formed between conducting polymers and noble metal nanoparticles have been examined using current-sensing atomic force microscopy (CS-AFM). Contacts formed between electrochemically prepared pi-conjugated polymer films such as polypyrrole (PPy), poly(3-methylthiophene) (P3MeT), as well as poly(3,4-ethylenedioxythiophene) (PEDOT) and noble metal nanoparticles including platinum (Pt), gold (Au), and silver (Ag) have been examined. The Pt nanoparticles were electrochemically deposited on a pre-coated PPy film surface by reducing a platinum precursor (PtCl62-) at a constant potential. Both current and scanning electron microscopic images of the film showed the presence of Pt islands. The Au and Ag nanoparticles were dispersed on the P3MeT and PEDOT film surfaces simply by dipping the polymer films into colloid solutions containing Au or Ag particles for specified periods (5 to approximately 10 min). The deposition of Au or Ag particles resulted from either their physical adsorption or chemical bonding between particles and the polymer surface depending on the polymer. When compared with PPy, P3MeT and PEDOT showed a stronger binding to Au or Ag nanoparticles when dipped in their colloidal solutions for the same period. This indicates that Au and Ag particles are predominantly linked with the sulfur atoms via chemical bonding. Of the two, PEDOT was more conductive at the sites where the particles are connected to the polymer. It appears that PEDOT has better aligned sulfur atoms on the surface and is strongly bonded to Au and Ag nanoparticles due to their strong affinity to gold and silver. The current-voltage curves obtained at the metal islands demonstrate that the contacts between these metal islands and polymers are ohmic.

Alternating magnetic field energy absorption in the dispersion of iron oxide nanoparticles in a viscous medium

Energy Technology Data Exchange (ETDEWEB)

Smolkova, Ilona S. [Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, nad Ovcirnou 3685, 760 01 Zlin (Czech Republic); Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, T.G. Masaryk Sq. 275, 762 72 Zlin (Czech Republic); Kazantseva, Natalia E., E-mail: nekazan@yahoo.com [Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, nad Ovcirnou 3685, 760 01 Zlin (Czech Republic); Babayan, Vladimir; Smolka, Petr; Parmar, Harshida; Vilcakova, Jarmila [Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, nad Ovcirnou 3685, 760 01 Zlin (Czech Republic); Schneeweiss, Oldrich; Pizurova, Nadezda [Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Zizkova 22, 616 62 Brno (Czech Republic)

2015-01-15

Magnetic iron oxide nanoparticles were obtained by a coprecipitation method in a controlled growth process leading to the formation of uniform highly crystalline nanoparticles with average size of 13 nm, which corresponds to the superparamagnetic state. Nanoparticles obtained are a mixture of single-phase nanoparticles of magnetite and maghemite as well as nanoparticles of non-stoichiometric magnetite. The subsequent annealing of nanoparticles at 300 °C in air during 6 h leads to the full transformation to maghemite. It results in reduced value of the saturation magnetization (from 56 emu g{sup −1} to 48 emu g{sup −1}) but does not affect the heating ability of nanoparticles. A 2–7 wt% dispersion of as-prepared and annealed nanoparticles in glycerol provides high heating rate in alternating magnetic fields allowed for application in magnetic hyperthermia; however the value of specific loss power does not exceed 30 W g{sup −1}. This feature of heat output is explained by the combined effect of magnetic interparticle interactions and the properties of the carrier medium. Nanoparticles coalesce during the synthesis and form aggregates showing ferromagnetic-like behavior with magnetization hysteresis, distinct sextets on Mössbauer spectrum, blocking temperature well about room temperature, which accounts for the higher energy barrier for magnetization reversal. At the same time, low specific heat capacity of glycerol intensifies heat transfer in the magnetic dispersion. However, high viscosity of glycerol limits the specific loss power value, since predominantly the Neel relaxation accounts for the absorption of AC magnetic field energy. - Highlights: • Mixed phase iron oxide magnetic nanoparticles were obtained by coprecipitation. • A part of nanoparticles was annealed at 300 °C to achieve the single-phase γ-Fe{sub 2}O{sub 3}. • Nanoparticles revealed ferromagnetic-like behavior due to interparticle interactions. • Nanoparticles glycerol

Dispersion and shape engineered plasmonic nanosensors

Science.gov (United States)

Jeong, Hyeon-Ho; Mark, Andrew G.; Alarcón-Correa, Mariana; Kim, Insook; Oswald, Peter; Lee, Tung-Chun; Fischer, Peer

2016-04-01

Biosensors based on the localized surface plasmon resonance (LSPR) of individual metallic nanoparticles promise to deliver modular, low-cost sensing with high-detection thresholds. However, they continue to suffer from relatively low sensitivity and figures of merit (FOMs). Herein we introduce the idea of sensitivity enhancement of LSPR sensors through engineering of the material dispersion function. Employing dispersion and shape engineering of chiral nanoparticles leads to remarkable refractive index sensitivities (1,091 nm RIU-1 at λ=921 nm) and FOMs (>2,800 RIU-1). A key feature is that the polarization-dependent extinction of the nanoparticles is now characterized by rich spectral features, including bipolar peaks and nulls, suitable for tracking refractive index changes. This sensing modality offers strong optical contrast even in the presence of highly absorbing media, an important consideration for use in complex biological media with limited transmission. The technique is sensitive to surface-specific binding events which we demonstrate through biotin-avidin surface coupling.

Chemical sensors based on molecularly modified metallic nanoparticles

International Nuclear Information System (INIS)

Haick, Hossam

2007-01-01

This paper presents a concise, although admittedly non-exhaustive, didactic review of some of the main concepts and approaches related to the use of molecularly modified metal nanoparticles in or as chemical sensors. This paper attempts to pull together different views and terminologies used in sensors based on molecularly modified metal nanoparticles, including those established upon electrochemical, optical, surface Plasmon resonance, piezoelectric and electrical transduction approaches. Finally, this paper discusses briefly the main advantages and disadvantages of each of the presented class of sensors. (review article)

Does nanoparticles dispersed in a phase change material improve melting characteristics?

NARCIS (Netherlands)

Farsani, Rouhollah Yadollahi; Raisi, Afrasiab; Nadooshan, Afshin Ahmadi; Vanapalli, Srinivas

2017-01-01

Nanoparticles dispersed in a phase change material alter the thermo-physical properties of the base material, such as thermal conductivity, viscosity, and specific heat capacity. These properties combined with the configuration of the cavity, and the location of the heat source, influence the

Removal of heavy metals in wastewater by using zeolite nano-particles impregnated polysulfone membranes

Energy Technology Data Exchange (ETDEWEB)

Yurekli, Yilmaz, E-mail: yilmazyurekli@gmail.com

2016-05-15

Highlights: • NaX addition significantly enhanced water hydraulic permeability of the membrane. • Metal exchange capacity of the membrane increased with the NaX content. • Hybrid membrane was efficient for the solutions with low metal concentrations - Abstract: In this study, the adsorption and the filtration processes were coupled by a zeolite nanoparticle impregnated polysulfone (PSf) membrane which was used to remove the lead and the nickel cations from synthetically prepared solutions. The results obtained from X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis indicated that the synthesized zeolite nanoparticles, using conventional hydrothermal method, produced a pure NaX with ultrafine and uniform particles. The performance of the hybrid membrane was determined under dynamic conditions. The results also revealed that the sorption capacity as well as the water hydraulic permeability of the membranes could both be improved by simply tuning the membrane fabricating conditions such as evaporation period of the casting film and NaX loading. The maximum sorption capacity of the hybrid membrane for the lead and nickel ions was measured as 682 and 122 mg/g respectively at the end of 60 min of filtration, under 1 bar of transmembrane pressure. The coupling process suggested that the membrane architecture could be efficiently used for treating metal solutions with low concentrations and transmembrane pressures.

In situ self-polymerization of unsaturated metal methacrylate and its dispersion mechanism in rubber-based composites

Energy Technology Data Exchange (ETDEWEB)

Wen, Shipeng; Zhou, Yao; Yao, Lu [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Zhang, Liqun [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Chan, Tung W. [Department of Materials Science and Engineering, Virginia Polytechnic Institute and State University, VA 24061 (United States); Liang, Yongri [Beijing National Laboratory for Molecular Sciences, Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Liu, Li, E-mail: LiuL@mail.buct.edu.cn [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

2013-11-10

Highlights: • In situ self-polymerization of unsaturated metal methacrylate was investigated mainly by the thermal effect. • UMM with low melting point can self-polymerize to a large extent. • The fine dispersion phase is composed of poly(UMM) nanoparticles formed by in situ self-polymerization in the rubber matrix. • The UMM crystals in the presence of peroxide and rubber undergo the processes of melting, diffusion, polymerization, and phase separation in this order. - Abstract: Unsaturated metal methacrylate (UMM) as one kind of functional filler has played an important role in reinforcing rubber materials. The in situ self-polymerization of UMM in UMM/rubber composite leads to the uniform dispersion of poly(UMM) in the rubber matrix, while the crosslinking of rubber and grafting between UMM and rubber chains occur simultaneously, making it difficult to clarify the effect of the in situ polymerization on the dispersion of poly(UMM) in the rubber matrix. In this work, we investigated the dispersion mechanism of UMM without rubber matrix for the first time using differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. Three types of UMMs including zinc methacrylate (Zn(MA){sub 2}), sodium methacrylate (Na(MA)) and samarium methacrylate (Sm(MA){sub 3}) were chosen to investigate the in situ self-polymerization of UMM. Based on DSC results, we conclude that the crystals with low melting point tend to self-polymerize first and generate a large amount of heat in the presence of peroxide. The high heat of reaction can melt the crystals with high melting point, and more UMM molecules are dissolved in the rubber matrix, thus increasing the extent of the in situ polymerization. Hence, the UMM with low melting point can self-polymerize to a large extent. Our findings provide in-depth understanding of the dispersion mechanism of UMM in rubber.

In situ self-polymerization of unsaturated metal methacrylate and its dispersion mechanism in rubber-based composites

International Nuclear Information System (INIS)

Wen, Shipeng; Zhou, Yao; Yao, Lu; Zhang, Liqun; Chan, Tung W.; Liang, Yongri; Liu, Li

2013-01-01

Highlights: • In situ self-polymerization of unsaturated metal methacrylate was investigated mainly by the thermal effect. • UMM with low melting point can self-polymerize to a large extent. • The fine dispersion phase is composed of poly(UMM) nanoparticles formed by in situ self-polymerization in the rubber matrix. • The UMM crystals in the presence of peroxide and rubber undergo the processes of melting, diffusion, polymerization, and phase separation in this order. - Abstract: Unsaturated metal methacrylate (UMM) as one kind of functional filler has played an important role in reinforcing rubber materials. The in situ self-polymerization of UMM in UMM/rubber composite leads to the uniform dispersion of poly(UMM) in the rubber matrix, while the crosslinking of rubber and grafting between UMM and rubber chains occur simultaneously, making it difficult to clarify the effect of the in situ polymerization on the dispersion of poly(UMM) in the rubber matrix. In this work, we investigated the dispersion mechanism of UMM without rubber matrix for the first time using differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. Three types of UMMs including zinc methacrylate (Zn(MA) 2 ), sodium methacrylate (Na(MA)) and samarium methacrylate (Sm(MA) 3 ) were chosen to investigate the in situ self-polymerization of UMM. Based on DSC results, we conclude that the crystals with low melting point tend to self-polymerize first and generate a large amount of heat in the presence of peroxide. The high heat of reaction can melt the crystals with high melting point, and more UMM molecules are dissolved in the rubber matrix, thus increasing the extent of the in situ polymerization. Hence, the UMM with low melting point can self-polymerize to a large extent. Our findings provide in-depth understanding of the dispersion mechanism of UMM in rubber

Simultaneous synthesis of polyaniline nanofibers and metal (Ag and Pt) nanoparticles

International Nuclear Information System (INIS)

Huang, Li-Ming; Liao, Wei-Hao; Ling, Han-Chern; Wen, Ten-Chin

2009-01-01

An approach for the synthesis of Ag/Pt nanoparticle-incorporated polyaniline (PANI) nanofibers and Ag/Pt nanoparticles was developed that considers both thermodynamic and kinetic aspects. Ag/Pt nanoparticles and PANI nanofibers are generated simultaneously by the reduction of Ag + /Pt 4+ ions to Ag/Pt nanoparticles and by the polymerization of aniline (ANI) to PANI nanofibers. The PANI nanofibers serve as anchor seeds for the formation of Ag/Pt nanoparticles. The simple and inexpensive route for the preparation of PANI-Ag/Pt nanocomposites can be extended to the polymerization of ANI derivatives and the formation of metal/metal oxides for applications such as sensors, direct methanol fuel cells, and capacitors.

Intense generation of respirable metal nanoparticles from a low-power soldering unit

Energy Technology Data Exchange (ETDEWEB)

Gómez, Virginia [Department of Chemical Engineering, Nanoscience Institute of Aragon (INA), 50018 Zaragoza (Spain); Irusta, Silvia [Department of Chemical Engineering, Nanoscience Institute of Aragon (INA), 50018 Zaragoza (Spain); Networking Biomedical Research Center of Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), 50018 Zaragoza (Spain); Balas, Francisco [Networking Biomedical Research Center of Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), 50018 Zaragoza (Spain); Instituto de Carboquímica – Consejo Superior de Investigaciones Científicas (ICB-CSIC), 50018 Zaragoza (Spain); Santamaria, Jesus, E-mail: Jesus.Santamaria@unizar.es [Department of Chemical Engineering, Nanoscience Institute of Aragon (INA), 50018 Zaragoza (Spain); Networking Biomedical Research Center of Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), 50018 Zaragoza (Spain)

2013-07-15

Highlights: • Intense generation of nanoparticles in the breathing range from a flux-soldering unit is detected. • Coagulation in the aerosol phase leads to 200-nm respirable nanoparticles up to 30 min after operation. • Nanoparticle concentration in the working environment depends on the presence of ambient air. • Metal-containing nanoparticles are collected in TEM grids and filters in the hundreds of nanometer range. -- Abstract: Evidence of intense nanoparticle generation from a low power (45 W) flux soldering unit is presented. This is a familiar device often used in daily life, including home repairs and school electronic laboratories. We demonstrate that metal-containing nanoparticles may reach high concentrations (ca. 10{sup 6} particles/cm{sup 3}) within the breathing range of the operator, with initial size distributions centered at 35–60 nm The morphological and chemical analysis of nanoparticle agglomerates collected on TEM grids and filters confirms their multiparticle structure and the presence of metals.

Intense generation of respirable metal nanoparticles from a low-power soldering unit

International Nuclear Information System (INIS)

Gómez, Virginia; Irusta, Silvia; Balas, Francisco; Santamaria, Jesus

2013-01-01

Highlights: • Intense generation of nanoparticles in the breathing range from a flux-soldering unit is detected. • Coagulation in the aerosol phase leads to 200-nm respirable nanoparticles up to 30 min after operation. • Nanoparticle concentration in the working environment depends on the presence of ambient air. • Metal-containing nanoparticles are collected in TEM grids and filters in the hundreds of nanometer range. -- Abstract: Evidence of intense nanoparticle generation from a low power (45 W) flux soldering unit is presented. This is a familiar device often used in daily life, including home repairs and school electronic laboratories. We demonstrate that metal-containing nanoparticles may reach high concentrations (ca. 10 6 particles/cm 3 ) within the breathing range of the operator, with initial size distributions centered at 35–60 nm The morphological and chemical analysis of nanoparticle agglomerates collected on TEM grids and filters confirms their multiparticle structure and the presence of metals

A Review on Metal Nanoparticles Nucleation and Growth on/in Graphene

OpenAIRE

Francesco Ruffino; Filippo Giannazzo

2017-01-01

In this review, the fundamental aspects (with particular focus to the microscopic thermodynamics and kinetics mechanisms) concerning the fabrication of graphene-metal nanoparticles composites are discussed. In particular, the attention is devoted to those fabrication methods involving vapor-phase depositions of metals on/in graphene-based materials. Graphene-metal nanoparticles composites are, nowadays, widely investigated both from a basic scientific and from several technological point of v...

Differential plasma protein binding to metal oxide nanoparticles

International Nuclear Information System (INIS)

Deng, Zhou J; Mortimer, Gysell; Minchin, Rodney F; Schiller, Tara; Musumeci, Anthony; Martin, Darren

2009-01-01

Nanoparticles rapidly interact with the proteins present in biological fluids, such as blood. The proteins that are adsorbed onto the surface potentially dictate the biokinetics of the nanomaterials and their fate in vivo. Using nanoparticles with different sizes and surface characteristics, studies have reported the effects of physicochemical properties on the composition of adsorbed plasma proteins. However, to date, few studies have been conducted focusing on the nanoparticles that are commonly exposed to the general public, such as the metal oxides. Using previously established ultracentrifugation approaches, two-dimensional gel electrophoresis and mass spectrometry, the current study investigated the binding of human plasma proteins to commercially available titanium dioxide, silicon dioxide and zinc oxide nanoparticles. We found that, despite these particles having similar surface charges in buffer, they bound different plasma proteins. For TiO 2 , the shape of the nanoparticles was also an important determinant of protein binding. Agglomeration in water was observed for all of the nanoparticles and both TiO 2 and ZnO further agglomerated in biological media. This led to an increase in the amount and number of different proteins bound to these nanoparticles. Proteins with important biological functions were identified, including immunoglobulins, lipoproteins, acute-phase proteins and proteins involved in complement pathways and coagulation. These results provide important insights into which human plasma proteins bind to particular metal oxide nanoparticles. Because protein absorption to nanoparticles may determine their interaction with cells and tissues in vivo, understanding how and why plasma proteins are adsorbed to these particles may be important for understanding their biological responses.

Impacts of metal and metal oxide nanoparticles on marine organisms

International Nuclear Information System (INIS)

Baker, Tony J.; Tyler, Charles R.; Galloway, Tamara S.

2014-01-01

Increasing use of metal and metal oxide nanoparticles [Me(O)NPs] in products means many will inevitably find their way into marine systems. Their likely fate here is sedimentation following hetero-aggregation with natural organic matter and/or free anions, putting benthic, sediment-dwelling and filter feeding organisms most at risk. In marine systems, Me(O)NPs can absorb to micro-organisms with potential for trophic transfer following consumption. Filter feeders, especially bivalves, accumulate Me(O)NPs through trapping them in mucus prior to ingestion. Benthic in-fauna may directly ingest sedimented Me(O)NPs. In fish, uptake is principally via the gut following drinking, whilst Me(O)NPs caught in gill mucus may affect respiratory processes and ion transport. Currently, environmentally-realistic Me(O)NP concentrations are unlikely to cause significant adverse acute health problems, however sub-lethal effects e.g. oxidative stresses have been noted in many organisms, often deriving from dissolution of Ag, Cu or Zn ions, and this could result in chronic health impacts. -- Highlights: • Nanoparticle (NP) use increasing, and NPs ultimately discharged to marine systems. • Metal ion dissolution from NPs causes oxidative stress at relevant concentrations. • Bioaccumulation and trophic transfer of NPs likely at all levels of marine food webs. • Biofilms and filter feeders are major NP accumulators, but many Classes lack study. • Current release levels unlikely to cause chronic damage, but may be a future issue. -- Exposure to metal (oxide) nanoparticles causes sub-lethal effects in marine organisms, the extent of which is related principally to the organisms' feeding regime, habitat and lifestyle

Nanostructured films of metal particles obtained by laser ablation

Energy Technology Data Exchange (ETDEWEB)

Muniz-Miranda, M., E-mail: muniz@unifi.it [Dipartimento di Chimica “U. Schiff”, Università di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino (Italy); Gellini, C. [Dipartimento di Chimica “U. Schiff”, Università di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino (Italy); Giorgetti, E.; Margheri, G.; Marsili, P. [Istituto Sistemi Complessi (CNR), Via Madonna del Piano 10, 50019 Sesto Fiorentino (Italy); Lascialfari, L.; Becucci, L. [Dipartimento di Chimica “U. Schiff”, Università di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino (Italy); Trigari, S. [Istituto Sistemi Complessi (CNR), Via Madonna del Piano 10, 50019 Sesto Fiorentino (Italy); Giammanco, F. [Dipartimento di Fisica “E. Fermi”, Università di Pisa, Largo Pontecorvo 3, 56127 Pisa (Italy)

2013-09-30

Colloidal dispersions of silver and gold nanoparticles were obtained in pure water by ablation with nanosecond pulsed laser. Then, by filtration of the metal particles on alumina, we fabricated nanostructured films, whose surface morphology was examined by atomic force microscopy (AFM) and related to surface-enhanced Raman scattering (SERS) after adsorption of adenine. - Highlights: • Ag and Au colloidal nanoparticles were obtained by laser ablation. • Nanostructured Ag and Au films were fabricated by filtration of metal nanoparticles. • Surface morphology of metal films was investigated by atomic force microscopy. • Surface-enhanced Raman spectra (SERS) of adenine on metal films were obtained. • SERS enhancements were related to the surface roughness of the metal films.

Metal-nanoparticle single-electron transistors fabricated using electromigration

DEFF Research Database (Denmark)

Bolotin, K I; Kuemmeth, Ferdinand; Pasupathy, A N

2004-01-01

We have fabricated single-electron transistors from individual metal nanoparticles using a geometry that provides improved coupling between the particle and the gate electrode. This is accomplished by incorporating a nanoparticle into a gap created between two electrodes using electromigration, all...... on top of an oxidized aluminum gate. We achieve sufficient gate coupling to access more than ten charge states of individual gold nanoparticles (5–15 nm in diameter). The devices are sufficiently stable to permit spectroscopic studies of the electron-in-a-box level spectra within the nanoparticle as its...

Electrocatalytic properties of monometallic and bimetallic nanoparticles-incorporated polypyrrole films for electro-oxidation of methanol

Energy Technology Data Exchange (ETDEWEB)

Selvaraj, V.; Alagar, M. [Department of Chemical Engineering, Alagappa College of Technology, Anna University, Chennai 600025 (India); Hamerton, I. [Chemistry Division, School of Biomedical and Molecular Sciences, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)

2006-10-06

Oxidative electrochemical polymerization of pyrrole at indium-doped tin oxide (ITO) is accomplished from a neat monomer solution with a supporting electrolyte (0.3M n-tetrabutyl ammonium tetrafluoroborate) by multiple-scan cyclic voltammetry. Polypyrrole (Ppy) films containing nanometer-sized platinum and Pt/Pd bimetallic particles are electro-synthesized on ITO glass plates by voltammetric cycling between -0.1 and +1V (versus Ag/AgCl/3M NaCl). The electrocatalytic oxidation of methanol on the nanoparticle-modified polypyrrole films is studied by means of electrochemical techniques. The modified electrode exhibits significant eletrocatalytic activity for methanol oxidation. The enhanced electrocatalytic activities may be due to the uniform dispersion of nanoparticles in the polypyrrole film and a synergistic effect of the highly-dispersed metal particles so that the polypyrrole film reduces electrode poisoning by adsorbed CO species. The monometallic (Pt) and bimetallic (Pt/Pd) nanoparticles are uniformly dispersed in polypyrrole matrixes, as confirmed by scanning electron microscopic and atomic force microscopic analysis. Energy dispersive X-ray analysis is used to characterize the composition of metal present in the nanoparticle-modified electrodes. (author)

Synthesis and characterization of water-dispersible core/shell Mn-doped magnetite/Au nanoparticles for proton radiotherapy

International Nuclear Information System (INIS)

Park, Jeong Chan

2015-01-01

The surface modification of the nanomaterials is required for the biomedical use to give physiological stability, surface reactivity and targeting properties. Among many approaches for the surface modification with materials, such as polymers, organic ligands and metals, one of the most attractive ways is to employ metals. The fabrication of metal-based, monolayer coated magnetic nanoparticles has been intensively studied. However, the synthesis of metal-capped magnetic nanoparticles with monodispersities and controllable sizes is still challenged. Recently, gold-capped magnetic nanoparticles have been reported to increase stability and to provide biocompatibility. Gold-coated magnetic nanoparticles are an attractive system, which can be stabilized in biological conditions and readily functionalized through well-established surface modification chemistry. In addition, the Au coating offers plasmonic properties to magnetic nanoparticles. This makes the magnetic/Au core/shell combinations interesting for magnetic and optical applications. The monodisperse Mn:Fe3O4/Au nanoparticles have been prepared in organic solvent first and then transferred from an organic phase to an aqueous solution. The resulting core/shell-structured nanoparticles may be an attractive system for biomedical applications, which are needed both magnetic resonance imaging and optical imaging. In addition, the resulting nanoparticles may be useful for proton radiotherapy due to the enhanced therapeutic effects of secondary radiation stemmed from gold and proton beam bombardment

Biomimetic Synthesis of Gelatin Polypeptide-Assisted Noble-Metal Nanoparticles and Their Interaction Study

Science.gov (United States)

Liu, Ying; Liu, Xiaoheng; Wang, Xin

2011-12-01

Herein, the generation of gold, silver, and silver-gold (Ag-Au) bimetallic nanoparticles was carried out in collagen (gelatin) solution. It first showed that the major ingredient in gelatin polypeptide, glutamic acid, acted as reducing agent to biomimetically synthesize noble metal nanoparticles at 80°C. The size of nanoparticles can be controlled not only by the mass ratio of gelatin to gold ion but also by pH of gelatin solution. Interaction between noble-metal nanoparticles and polypeptide has been investigated by TEM, UV-visible, fluorescence spectroscopy, and HNMR. This study testified that the degradation of gelatin protein could not alter the morphology of nanoparticles, but it made nanoparticles aggregated clusters array (opposing three-dimensional α-helix folding structure) into isolated nanoparticles stabilized by gelatin residues. This is a promising merit of gelatin to apply in the synthesis of nanoparticles. Therefore, gelatin protein is an excellent template for biomimetic synthesis of noble metal/bimetallic nanoparticle growth to form nanometer-sized device.

Extracellular Proteins Limit the Dispersal of BiogenicNanoparticles

Energy Technology Data Exchange (ETDEWEB)

Moreau, John W.; Weber, Peter K.; Martin, Michael C.; Gilbert,Benjamin; Hutcheon, Ian D.; Banfield, Jillian F.

2007-04-27

High spatial-resolution secondaryion microprobespectrometry, synchrotron radiation Fourier-transform infraredspectroscopy and polyacrylamide gel analysis demonstrate the intimateassociation of proteins with spheroidal aggregates of biogenic zincsulfide nanocrystals, an example of extracellular biomineralization.Experiments involving synthetic ZnS nanoparticles and representativeamino acids indicate a driving role for cysteine in rapid nanoparticleaggregation. These findings suggest that microbially-derivedextracellular proteins can limit dispersal of nanoparticulatemetal-bearing phases, such as the mineral products of bioremediation,that may otherwise be transported away from their source by subsurfacefluid flow.

Metal Catalysts for Heterogeneous Catalysis: From Single Atoms to Nanoclusters and Nanoparticles.

Science.gov (United States)

Liu, Lichen; Corma, Avelino

2018-05-23

Metal species with different size (single atoms, nanoclusters, and nanoparticles) show different catalytic behavior for various heterogeneous catalytic reactions. It has been shown in the literature that many factors including the particle size, shape, chemical composition, metal-support interaction, and metal-reactant/solvent interaction can have significant influences on the catalytic properties of metal catalysts. The recent developments of well-controlled synthesis methodologies and advanced characterization tools allow one to correlate the relationships at the molecular level. In this Review, the electronic and geometric structures of single atoms, nanoclusters, and nanoparticles will be discussed. Furthermore, we will summarize the catalytic applications of single atoms, nanoclusters, and nanoparticles for different types of reactions, including CO oxidation, selective oxidation, selective hydrogenation, organic reactions, electrocatalytic, and photocatalytic reactions. We will compare the results obtained from different systems and try to give a picture on how different types of metal species work in different reactions and give perspectives on the future directions toward better understanding of the catalytic behavior of different metal entities (single atoms, nanoclusters, and nanoparticles) in a unifying manner.

Homogeneous dispersion of gadolinium oxide nanoparticles into a non-aqueous-based polymer by two surface treatments

Energy Technology Data Exchange (ETDEWEB)

Samuel, Jorice, E-mail: jorice.samuel@gmail.com [AREVA T and D UK Ltd, AREVA T and D Research and Technology Centre (United Kingdom); Raccurt, Olivier [NanoChemistry and Nanosafety Laboratory (DRT/LITEN/DTNM/LCSN), CEA Grenoble, Department of NanoMaterials (France); Mancini, Cedric; Dujardin, Christophe; Amans, David; Ledoux, Gilles [Universite de Lyon, Laboratoire de Physico Chimie des Materiaux Luminescents (LPCML) (France); Poncelet, Olivier [NanoChemistry and Nanosafety Laboratory (DRT/LITEN/DTNM/LCSN), CEA Grenoble, Department of NanoMaterials (France); Tillement, Olivier [Universite de Lyon, Laboratoire de Physico Chimie des Materiaux Luminescents (LPCML) (France)

2011-06-15

Gadolinium oxide nanoparticles are more and more used. They can notably provide interesting fluorescence properties. Herein they are incorporated into a non-aqueous-based polymer, the poly(methyl methacrylate). Their dispersion within the polymer matrix is the key to improve the composite properties. As-received gadolinium oxide nanopowders cannot be homogeneously dispersed in such a polymer matrix. Two surface treatments are, therefore, detailed and compared to achieve a good stability of the nanoparticles in a non-aqueous solvent such as the 2-butanone. Then, once the liquid suspensions have been stabilized, they are used to prepare nanocomposites with homogeneous particles dispersion. The two approaches proposed are an hybrid approach based on the growth of a silica shell around the gadolinium oxide nanoparticles, and followed by a suitable silane functionalization; and a non-hybrid approach based on the use of surfactants. The surface treatments and formulations involved in both methods are detailed, adjusted and compared. Thanks to optical methods and in particular to the use of a 'home made' confocal microscope, the dispersion homogeneity within the polymer can be assessed. Both methods provide promising and conclusive results.

The mechanism of metal nanoparticle formation in plants: limits on accumulation

Energy Technology Data Exchange (ETDEWEB)

Haverkamp, R. G., E-mail: r.haverkamp@massey.ac.nz; Marshall, A. T. [Massey University, School of Engineering and Advanced Technology (New Zealand)

2009-08-15

Metal nanoparticles have many potential technological applications. Biological routes to the synthesis of these particles have been proposed including production by vascular plants, known as phytoextraction. While many studies have looked at metal uptake by plants, particularly with regard to phytoremediation and hyperaccumulation, few have distinguished between metal deposition and metal salt accumulation. This work describes the uptake of AgNO{sub 3}, Na{sub 3}Ag(S{sub 2}O{sub 3}){sub 2}, and Ag(NH{sub 3}){sub 2}NO{sub 3} solutions by hydroponically grown Brassica juncea and the quantitative measurement of the conversion of these salts to silver metal nanoparticles. Using X-ray absorption near edge spectroscopy (XANES) to determine the metal speciation within the plants, combined with atomic absorption spectroscopy (AAS) for total Ag, the quantity of reduction of Ag{sup I} to Ag{sup 0} is reported. Transmission electron microscopy (TEM) showed Ag particles of 2-35 nm. The factors controlling the amount of silver accumulated are revealed. It is found that there is a limit on the amount of metal nanoparticles that may be deposited, of about 0.35 wt.% Ag on a dry plant basis, and that higher levels of silver are obtained only by the concentration of metal salts within the plant, not by deposition of metal. The limit on metal nanoparticle accumulation, across a range of metals, is proposed to be controlled by the total reducing capacity of the plant for the reduction potential of the metal species and limited to reactions occurring at an electrochemical potential greater than 0 V (verses the standard hydrogen electrode).

Enzymatic biosensors based on the use of metal oxide nanoparticles

International Nuclear Information System (INIS)

Shi, Xinhao; Gu, Wei; Li, Bingyu; Chen, Ningning; Zhao, Kai; Xian, Yuezhong

2014-01-01

Over the past decades, various techniques have been developed to obtain materials at a nanoscale level to design biosensors with high sensitivity, selectivity and efficiency. Metal oxide nanoparticles (MONPs) are of particular interests and have received much attention because of their unique physical, chemical and catalytic properties. This review summarizes the progress made in enzymatic biosensors based on the use of MONPs. Synthetic methods, strategies for immobilization, and the functions of MONPs in enzymatic biosensing systems are reviewed and discussed. The article is subdivided into sections on enzymatic biosensors based on (a) zinc oxide nanoparticles, (b) titanium oxide nanoparticles, (c) iron oxide nanoparticles, and (d) other metal oxide nanoparticles. While substantial advances have been made in MONPs-based enzymatic biosensors, their applications to real samples still lie ahead because issues such as reproducibility and sensor stability have to be solved. (author)

Dissecting the structure of surface stabilizer on the dispersion of inorganic nanoparticles in aqueous medium

Energy Technology Data Exchange (ETDEWEB)

Ding, Yong; Yu, Zongzhi; Zheng, Junping, E-mail: jpzheng@tju.edu.cn [Tianjin University, Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering (China)

2017-03-15

Dispersing inorganic nanoparticles in aqueous solutions is a key requirement for a great variety of products and processes, including carriers in drug delivery or fillers in polymers. To be highly functional in the final product, inorganic particles are required to be finely dispersed in nanoscale. In this study, silica was selected as a representative inorganic particle. Surface stabilizers with different chain length and charged group were designed to reveal the influence of electrostatic and van der Waals forces between silica and stabilizer on the dispersion of silica particles in aqueous medium. Results showed surface stabilizer with longer alkyl chain and charged group exerted best ability to deaggregate silica, leading to a hydrodynamic size of 51.1 nm. Surface stabilizer designing with rational structure is a promising solution for deagglomerating and reducing process time and energy. Giving the designability and adaptability of surface stabilizer, this method is of potential for dispersion of other inorganic nanoparticles.

Dissecting the structure of surface stabilizer on the dispersion of inorganic nanoparticles in aqueous medium

Science.gov (United States)

Ding, Yong; Yu, Zongzhi; Zheng, Junping

2017-03-01

Dispersing inorganic nanoparticles in aqueous solutions is a key requirement for a great variety of products and processes, including carriers in drug delivery or fillers in polymers. To be highly functional in the final product, inorganic particles are required to be finely dispersed in nanoscale. In this study, silica was selected as a representative inorganic particle. Surface stabilizers with different chain length and charged group were designed to reveal the influence of electrostatic and van der Waals forces between silica and stabilizer on the dispersion of silica particles in aqueous medium. Results showed surface stabilizer with longer alkyl chain and charged group exerted best ability to deaggregate silica, leading to a hydrodynamic size of 51.1 nm. Surface stabilizer designing with rational structure is a promising solution for deagglomerating and reducing process time and energy. Giving the designability and adaptability of surface stabilizer, this method is of potential for dispersion of other inorganic nanoparticles.

Surface effects in metallic iron nanoparticles

DEFF Research Database (Denmark)

Bødker, Franz; Mørup, Steen; Linderoth, Søren

1994-01-01

Nanoparticles of metallic iron on carbon supports have been studied in situ by use of Mossbauer spectroscopy. The magnetic anisotropy energy constant increases with decreasing particle size, presumably because of the influence of surface anisotropy. Chemisorption of oxygen results in formation...

Novel routes to metal nanoparticles : electrodeposition and reactions at liquid-liquid interfaces

OpenAIRE

Johans, Christoffer

2003-01-01

This thesis considers the nucleation and growth, synthesis, and catalytic application of metallic nanoparticles at liquid|liquid interfaces. It comprises five publications, a previously unpublished synthesis of polymer coated palladium nanoparticles, and an introduction to the relevant literature. Three publications are concerned with electrodeposition of metal nanoparticles at liquid|liquid interfaces. One publication and the results presented here consider the synthesis of silver and pallad...

Ductility Enhancement of Molybdenum Phase by Nano-sizedd Oxide Dispersions

Energy Technology Data Exchange (ETDEWEB)

Bruce Kang

2008-07-31

The present research is focused on ductility enhancement of molybdenum (Mo) alloys by adding nano-sized oxide particles to the alloy system. The research approach includes: (1) determination of microscopic mechanisms responsible for the macroscopic ductility enhancement effects through atomistic modeling of the metal-ceramic interface; (2) subsequent computer simulation-aided optimization of composition and nanoparticle size of the dispersion for improved performance; (3) synthesis and characterization of nanoparticle dispersion following the guidance from atomistic computational modeling analyses (e.g., by processing a small sample of Mo alloy for evaluation); and (4) experimental testing of the mechanical properties to determine optimal ductility enhancement.Through atomistic modeling and electronic structure analysis using full-potential linearized muffin-tin orbital (FP-LMTO) techniques, research to date has been performed on a number of selected chromium (Cr) systems containing nitrogen (N) and/or magnesium oxide (MgO) impurities. The emphasis has been on determining the properties of the valence electrons and the characteristics of the chemical bonds they formed. It was found that the brittle/ductile behavior of this transitional metal system is controlled by the relative population of valence charges: bonds formed by s valence electrons yield metallic, ductile behavior, whereas bonds formed by d valence electrons lead to covalent, brittle behavior. The presence of valence bands from impurities also affects the metal bonding, thereby explaining the detrimental and beneficial effects induced by the inclusion of N impurities and MgO dispersions. These understandings are useful for optimizing ductility enhancement effects on the dispersion materials.

Biogenic synthesis of metallic nanoparticles and prospects toward green chemistry.

Science.gov (United States)

Adil, Syed Farooq; Assal, Mohamed E; Khan, Mujeeb; Al-Warthan, Abdulrahman; Siddiqui, Mohammed Rafiq H; Liz-Marzán, Luis M

2015-06-07

The immense importance of nanoparticles and their applications is a strong motivation for exploring new synthetic techniques. However, due to strict regulations that manage the potential environmental impacts greener alternatives for conventional synthesis are the focus of intense research. In the scope of this perspective, a concise discussion about the use of green reducing and stabilizing agents toward the preparation of metal nanoparticles is presented. Reports on the synthesis of noble metal nanoparticles using plant extracts, ascorbic acid and sodium citrate as green reagents are summarized and discussed, pointing toward an urgent need of understanding the mechanistic aspects of the involved reactions.

Microstructural characterisation of electrodeposited coatings of metal matrix composite with alumina nanoparticles

International Nuclear Information System (INIS)

Indyka, P; Beltowska-Lehman, E; Bigos, A

2012-01-01

In the present work a nanocrystalline Ni-W metallic matrix was used to fabricate Ni-W/Al 2 O 3 composite coatings. The MMC (metal matrix composite) coatings with inert α-Al 2 O 3 particles (30 - 90 nm) were electrodeposited from aqueous electrolytes under direct current (DC) and controlled hydrodynamic conditions in a system with a rotating disk electrode (RDE). The chemical composition and microstructure of electrodeposited composites mainly control their functional properties; however, the particles must be uniformly dispersed to exhibit the dispersion-hardening effect. In order to increase the alumina particles incorporation as well as to promote the uniform distribution of the ceramic phase in a matrix, outer ultrasonic field was applied during electrodeposition. The influence of embedded alumina nanoparticles on structural characteristics (morphology, phase composition, residual stresses) of the resulting Ni-W/Al 2 O 3 coatings was investigated in order to obtain a nanocomposite with high hardness and relatively low residual stresses. Surface and cross-section morphology and the chemical composition of deposits was examined in the scanning electron microscope, the EDS technique was used. Microstructure and phase composition were determined by transmission electron microscopy and X-ray diffraction. Based on microstructural and micromechanical properties of the coatings, the optimum conditions for obtaining crack-free homogeneous Ni-W/Al 2 O 3 composite coatings have been determined.

Actual problems of exposure risk assessment of finely dispersed aerosols and aerosols of nanoparticles

Directory of Open Access Journals (Sweden)

A. I. Sevalnev

2018-04-01

Full Text Available Purpose of the study – analysis of the scientific literature on generalization of the data on domestic and foreign experience in risk assessment due to exposure to finely dispersed aerosols and aerosols of nanoparticles (NPs. The article summarizes data of long-term studies on the effect of nanomaterials and nanoparticles on the quality of human habitat and health. The domestic and foreign experience of harm health assessment, safety of new types of nanomaterials for the environment and work-related conditions have been analyzed. There are numerous studies of foreign and domestic scientists on the biological activity of nanoparticles and their effect on experimental animals, namely, on the specificity of their effect on various organs and systems of the body. Classification of nanomaterials, depending on their chemical composition, is presented. Attention is paid to the problems of nanosafety, namely, to the evaluation of nanotoxicity of substances and to the definition of the concept of a “dose” for nanoparticles. The data on the presence of finely dispersed and ultra-fine particles in the atmospheric air, which increase risk of respiratory system diseases among residents of large megacities, is given. There is special importance on assessing work conditions and occupational risks in production and use of materials which contain nanoparticles as well as in production processes with formation of the fine dust and nanoparticles indicated in the article. Due to the lack of a clear system for assessing health risks related to the action of nanoparticles, lack of common criteria of harmfulness and maximum allowable concentrations for most nanoparticles and uniform methods of their control, it is suggested to strictly adhere to protective measures in contact with nanomaterials and active improvement of nanosecurity measures. Conclusions. High toxicity and health hazards of finely dispersed and ultra-fine particles confirm need to control their

Quantifying the impact of relativity and of dispersion interactions on the activation of molecular oxygen promoted by noble metal nanoparticles

KAUST Repository

Kanoun, Mohammed

2014-06-26

We compared the mechanism of O2 dissociation catalyzed by Cu38, Ag38, and Au38 nanoparticles. Overall, our results indicate that O2 dissociation is extremely easy on Cu38, with an almost negligible barrier for the O-O breaking step. It presents an energy barrier close to 20 kcal/mol on Ag38, which decreases to slightly more than 10 kcal/mol on Au38. This behavior is analyzed to quantify the impact of relativity and of dispersion interactions through a comparison of nonrelativistic, scalar-relativistic, and dispersioncorrected DFT methods. Nonrelativistic calculations show a clear trend down the triad, with larger in size nanoparticle (NP), weaker O2 adsorption energy, and higher O2 dissociation barrier, which is so high for Au38 to be in sharp contrast with the mild conditions used experimentally. Inclusion of relativity has no impact on the O2 adsorption energy, but it reduces the energy barrier for O2 dissociation on Au38 from 30.1 to 11.4 kcal/mol, making it even lower than that on Ag38 and consistent with the mild conditions used experimentally. Dispersion interactions have a remarkable role in improving the adsorption ability of O2 on the heavier Ag38 and especially Au38 NPs, contributing roughly 50% of the total adsorption energy, while they have much less impact on O2 adsorption on Cu38.

Single-site catalyst promoters accelerate metal-catalyzed nitroarene hydrogenation

KAUST Repository

Wang, Liang

2018-04-04

Atomically dispersed supported metal catalysts are drawing wide attention because of the opportunities they offer for new catalytic properties combined with efficient use of the metals. We extend this class of materials to catalysts that incorporate atomically dispersed metal atoms as promoters. The catalysts are used for the challenging nitroarene hydrogenation and found to have both high activity and selectivity. The promoters are single-site Sn on TiO2 supports that incorporate metal nanoparticle catalysts. Represented as M/Sn-TiO2 (M = Au, Ru, Pt, Ni), these catalysts decidedly outperform the unpromoted supported metals, even for hydrogenation of nitroarenes substituted with various reducible groups. The high activity and selectivity of these catalysts result from the creation of oxygen vacancies on the TiO2 surface by single-site Sn, which leads to efficient, selective activation of the nitro group coupled with a reaction involving hydrogen atoms activated on metal nanoparticles.

Single-site catalyst promoters accelerate metal-catalyzed nitroarene hydrogenation

KAUST Repository

Wang, Liang; Guan, Erjia; Zhang, Jian; Yang, Junhao; Zhu, Yihan; Han, Yu; Yang, Ming; Cen, Cheng; Fu, Gang; Gates, Bruce C.; Xiao, Feng-Shou

2018-01-01

Atomically dispersed supported metal catalysts are drawing wide attention because of the opportunities they offer for new catalytic properties combined with efficient use of the metals. We extend this class of materials to catalysts that incorporate atomically dispersed metal atoms as promoters. The catalysts are used for the challenging nitroarene hydrogenation and found to have both high activity and selectivity. The promoters are single-site Sn on TiO2 supports that incorporate metal nanoparticle catalysts. Represented as M/Sn-TiO2 (M = Au, Ru, Pt, Ni), these catalysts decidedly outperform the unpromoted supported metals, even for hydrogenation of nitroarenes substituted with various reducible groups. The high activity and selectivity of these catalysts result from the creation of oxygen vacancies on the TiO2 surface by single-site Sn, which leads to efficient, selective activation of the nitro group coupled with a reaction involving hydrogen atoms activated on metal nanoparticles.

Dispersion of Pt Nanoparticle-Doped Reduced Graphene Oxide Using Aniline as a Stabilizer

Directory of Open Access Journals (Sweden)

Hyoung-Joon Jin

2012-12-01

Full Text Available In this study, a simple one-step method was developed to load small-sized Pt nanoparticles (3.1 ± 0.3 nm in large quantities (50 wt % on aniline-functionalized and reduced graphene oxide (r-fGO. In the process, an ethylene glycol solution and aniline-functionalized moiety play the roles of reducing agent and stabilizer for the Pt nanoparticles, respectively, without damaging the graphite structures of the r-fGO. The Pt nanoparticles loading on the surface of r-fGO with uniform dispersion have a great effect on the electrical conductivity.

Size and shape dependent lattice parameters of metallic nanoparticles

International Nuclear Information System (INIS)

Qi, W. H.; Wang, M. P.

2005-01-01

A model is developed to account for the size and shape dependent lattice parameters of metallic nanoparticles, where the particle shape difference is considered by introducing a shape factor. It is predicted that the lattice parameters of nanoparticles in several nanometers decrease with decreasing of the particle size, which is consistent with the corresponding experimental results. Furthermore, it is found that the particle shape can lead to 10% of the total lattice variation. The model is a continuous media model and can deal with the nanoparticles larger than 1 nm. Since the shape factor approaches to infinity for nanowires and nanofilms, therefore, the model cannot be generalized to the systems of nanowires and nanofilms. For the input parameters are physical constants of bulk materials, therefore, the present model may be used to predict the lattice variation of different metallic nanoparticles with different lattice structures

Theoretical Aspects of Phonon Dispersion Curves for Metals

International Nuclear Information System (INIS)

Cochran, W.

1965-01-01

Reasonably complete knowledge of the phonon dispersion curves for at least a dozen metallic elements and intermetallic compounds has now been obtained from neutron inelastic scattering experiments. The results have one feature in common: when analysed in terms of interatomic force constants they reveal the presence of comparatively long-range forces extending over several atomic spacings. The results for lead are particularly interesting; it did not prove possible to fit them by a force-constant model, but the dispersion curves for wave vectors in symmetry directions when analysed in terms of force constants between planes of atoms showed an oscillatory interatomic potential extending over distances of more than 20Å. This review is concerned with recent theoretical work which has a bearing on the calculation of phonon dispersion curves for metals and the explanation of the long range of the interatomic potential. The best hope at present for a general treatment of atomic interaction in metals appears to lie in the ''method of neutral pseudo-atoms'', (a description recently coined by Ziman). This approximate theory is outlined and its relevance to Kohn anomalies in phonon dispersion curves is discussed. Experimental data for sodium is consistent with the theory, and the interatomic potential in sodium varies periodically in a distance π/k F , where fik F is the Fermi momentum, as has already been demonstrated by Koenig in a different way. More exact calculations have been made for sodium by Toya and by Sham. The relationship between the different methods and other work of a more general character such as that of Harrison are discussed. (author) [fr

Conductometric gas sensors based on metal oxides modified with gold nanoparticles: a review

International Nuclear Information System (INIS)

Korotcenkov, Ghenadii; Cho, Beong K.; Brinzari, Vladimir

2016-01-01

This review (with 170 refs.) discusses approaches towards surface functionalizaton of metal oxides by gold nanoparticles, and the application of the resulting nanomaterials in resistive gas sensors. The articles is subdivided into sections on (a) methods for modification of metal oxides with gold nanoparticles; (b) the response of gold nanoparticle-modified metal oxide sensors to gaseous species, (c) a discussion of the limitations of such sensors, and (d) a discussion on future tasks and trends along with an outlook. It is shown that, in order to achieve significant improvements in sensor parameters, it is necessary to warrant a good control the size and density of gold nanoparticles on the surface of metal oxide crystallites, the state of gold in the cluster, and the properties of the metal oxide support. Current challenges include an improved reproducibility of sensor preparation, better long-term stabilities, and a better resistance to sintering and poisoning of gold clusters during operation. Additional research focused on better understanding the role of gold clusters and nanoparticles in gas-sensing effects is also required. (author)

A review on radiation-induced nucleation and growth of colloidal metallic nanoparticles

OpenAIRE

Abedini, Alam; Daud, Abdul Razak; Abdul Hamid, Muhammad Azmi; Kamil Othman, Norinsan; Saion, Elias

2013-01-01

This review presents an introduction to the synthesis of metallic nanoparticles by radiation-induced method, especially gamma irradiation. This method offers some benefits over the conventional methods because it provides fully reduced and highly pure nanoparticles free from by-products or chemical reducing agents, and is capable of controlling the particle size and structure. The nucleation and growth mechanism of metallic nanoparticles are also discussed. The competition between nucleation ...

Manufacturing and Morphological Analysis of Composite Material of Polystyrene Nanospheres/Cadmium Metal Nanoparticles

Directory of Open Access Journals (Sweden)

Pratama Jujur Wibawa

2013-03-01

Full Text Available A very simple nanocomposite material has been in-situ manufactured from an aqueous polystyrene nanospheres dispersion and cadmium (Cd metal nanoparticles. The manufacturing was performed by using a high frequency of 40 kHz ultrasonic (US agitation for 45 minute at atmospheric pressure and at room temperature 20 oC. No chemical reducing agent and surfactant added in this manufacturing technique due to the US could reduce Cd2+ ions of cadmium nitrate tetrahydrate to Cd atomic metals nanoparticles whereas water molecules could act as a pseudo stabilizer for the manufactured material. A thin film was manufactured from aqueous colloidal nanocomposite material of Polystyrene nanospheres/Cd metal nanoparticles (PSNs/CdMNp fabricated on a hydrophilic silicon wafer. The thin film was then characterized by a JEOL-FESEM for its surface morphology characteristic and by ATR-FTIR spectrometry for its molecular change investigation. It could be clearly observed that surface morphology of the thin film material was not significantly changed under 633 nm wavelength continuous laser radiation exposure for 20 minute. In addition, its ATR-FTIR spectra of wave number peaks around 3400 cm-1 have been totally disappeared under the laser exposure whereas that at around 699 cm-1 and 668 cm-1 have not been significantly changed. The first phenomenon indicated that the hydrogen bond existed in PSNs/CdMNp material was collapsed by the laser exposure. The second phenomena indicated that the PSNs phenyl ring moiety was not totally destroyed under the laser exposure. It was suspected due to the existence of Cd nanoparticles covered throughout the spherical surface of PSNs/CdMNp material particles. Therefore a nice model of material structure of the mentioned PSNs/CdMNp nanocomposite material could be suggested in this research. It could be concluded that this research have been performed since the material structure model of the manufactured PSNs/CdMNp nanocomposite could be

Bioactivity of noble metal nanoparticles decorated with biopolymers and their application in drug delivery.

Science.gov (United States)

Rai, Mahendra; Ingle, Avinash P; Gupta, Indarchand; Brandelli, Adriano

2015-12-30

The unique properties of nanomaterials can be applied to solve different problems including new ways of drug delivery. Noble metal nanoparticles are most promising because they have been used for medicinal purposes since ancient time. It is evident from the past studies that the metallic nanoparticles are much more effective against various microorganisms when compared to their conventional counterparts. However, decoration of such nanoparticles with biomaterials add more advantages to their antimicrobial activity. Decoration of metal nanoparticles with biopolymers is a quite new area of research. Studies performed hitherto shown that nanoparticles of noble metals like silver, gold and platinum demonstrated better antibacterial, antifungal and antiviral activities when conjugated with biopolymers. The development of such technology has potential to develop materials that are more effective in the field of health science. Considering the importance and uniqueness of this concept, the present review aims to discuss the use of biopolymer-decorated metal nanoparticles for combating various diseases caused by microbial pathogens. Moreover, the nanotoxicity aspect has also been discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

Flexible transparent conducting films with embedded silver networks composed of bimodal-sized nanoparticles for heater application

Science.gov (United States)

Park, Ji Sun; Song, Yookyung; Park, Daseul; Kim, Yeon-Won; Kim, Yoon Jin

2018-06-01

A facile one-pot synthetic method for preparing the Ag nanoparticle inks with a bimodal size distribution was newly devised and they were successfully employed as a conducting filler to form the metal-mesh type transparent conducting electrodes on the flexible substrate. Bimodal-sized Ag nanoparticles were synthesized through the polyol process, and their size variation was occurred via finely tuned composition ratio between Ag+ ions and polymeric capping agents. The prepared bimodal-sized Ag nanoparticles exhibited the form of well-dispersed Ag nanoparticle inks without adding any dispersants and dispersion process. By filling the patterned micro-channels engraved on the flexible polymer substrate using a bimodal-sized Ag nanoparticle ink, a metal-mesh type transparent electrode (transmittance: 90% at 550 nm, haze: 1.5, area: 8 × 8 cm2) was fabricated. By applying DC voltage to the mesh type electrode, a flexible transparent joule heater was successfully achieved with a performance of 4.5 °C s‑1 heat-up rate at a low input power density.

Surface energy of metal alloy nanoparticles

Science.gov (United States)

Takrori, Fahed M.; Ayyad, Ahmed

2017-04-01

The measurement of surface energy of alloy nanoparticles experimentally is still a challenge therefore theoretical work is necessary to estimate its value. In continuation of our previous work on the calculation of the surface energy of pure metallic nanoparticles we have extended our work to calculate the surface energy of different alloy systems, namely, Co-Ni, Au-Cu, Cu-Al, Cu-Mg and Mo-Cs binary alloys. It is shown that the surface energy of metallic binary alloy decreases with decreasing particle size approaching relatively small values at small sizes. When both metals in the alloy obey the Hume-Rothery rules, the difference in the surface energy is small at the macroscopic as well as in the nano-scale. However when the alloy deviated from these rules the difference in surface energy is large in the macroscopic and in the nano scales. Interestingly when solid solution formation is not possible at the macroscopic scale according to the Hume-Rothery rules, it is shown it may form at the nano-scale. To our knowledge these findings here are presented for the first time and is challenging from fundamental as well as technological point of views.

Semiconductor-metal transition of Se in Ru-Se Catalyst Nanoparticles

Science.gov (United States)

Babu, P. K.; Lewera, Adam; Oldfield, Eric; Wieckowski, Andrzej

2009-03-01

Ru-Se composite nanoparticles are promising catalysts for the oxygen reduction reaction (ORR) in fuel cells. Though the role of Se in enhancing the chemical stability of Ru nanoparticles is well established, the microscopic nature of Ru-Se interaction was not clearly understood. We carried out a combined investigation of ^77Se NMR and XPS on Ru-Se nanoparticles and our results indicate that Se, a semiconductor in elemental form, becomes metallic when interacting with Ru. ^77Se spin-lattice relaxation rates are found to be proportional to T, the well-known Korringa behavior characteristic of metals. The NMR results are supported by the XPS binding energy shifts which suggest that a possible Ru->Se charge transfer could be responsible for the semiconductor->metal transition of Se which also makes Ru less susceptible to oxidation during ORR.

Hydrothermal Synthesis of Highly Water-dispersible Anatase Nanoparticles with Large Specific Surface Area and Their Adsorptive Properties

OpenAIRE

Hu Xueting; Zhang Dongyun; Zhao Siqin; Asuha Sin

2016-01-01

Highly water-dispersible and very small TiO2 nanoparticles (~3 nm anatase) with large specific surface area have been synthesized by hydrolysis and hydrothermal reactions of titanium butoxide and used for the removal of three azo dyes (Congo red, orange II, and methyl orange) with different molecular structure from simulated wastewaters. The synthesized TiO2 nanoparticles are well dispersed in water with large specific surface area up to 417 m2 g−1. Adsorption experiments demonstrated that th...

Fabrication of metallic nanoparticles by spinodal dewetting of thin films: A high-throughput approach

Energy Technology Data Exchange (ETDEWEB)

Michalak, William D.; Miller, James B. [U.S. Department of Energy, National Energy Technology Laboratory, Pittsburgh, PA 15262 (United States); Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Yolcu, Cem [Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Gellman, Andrew J., E-mail: gellman@cmu.edu [U.S. Department of Energy, National Energy Technology Laboratory, Pittsburgh, PA 15262 (United States); Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213 (United States)

2012-11-01

Metal nanoparticles on structured supports are used in a variety of technological applications including biosensing, energy harvesting, and electronics. In every case, the functions and properties of the metallic nanostructures depend on both their composition and structure (i.e. size, shape, and spatial distribution). Among the challenges to the development of metal nanoparticles for these applications is the characterization of relationships between their structure and their functional properties over multiple structural degrees of freedom spanning a large range of values. In this work, a method for creating a morphological gradient of metal nanoparticles on a substrate is described. The approach, suited for high-throughput fabrication and characterization, is based on spinodal dewetting of a metallic thin film from its substrate. Through control of initial film thickness, anneal temperature, and anneal time, spinodal dewetting results in supported nanoparticles with well-defined and controlled structure. The approach is demonstrated through its application to preparation of Pd nanoparticles on a silicon nitride substrate. The morphologies of the particles were characterized by scanning electron and atomic force microscopies. Free energy-based stability and topological analyses were used to confirm the dewetting mechanism. In addition, the stability theory provides a connection to the thermophysical properties of the resulting nanoparticle array. The dewetting approach is general to any metal/support system and provides an alternative, inexpensive, and robust means to rapidly create metal nanostructures with control of morphology. It shows promise for large scale production of metal nanoparticles structures, as well as understanding basic stability properties of thin metal films. - Highlights: Black-Right-Pointing-Pointer Pd dewetting from SiN occurs by a spinodal dewetting mechanism. Black-Right-Pointing-Pointer Dewetting occurs at temperatures well below the

Fabrication of metallic nanoparticles by spinodal dewetting of thin films: A high-throughput approach

International Nuclear Information System (INIS)

Michalak, William D.; Miller, James B.; Yolcu, Cem; Gellman, Andrew J.

2012-01-01

Metal nanoparticles on structured supports are used in a variety of technological applications including biosensing, energy harvesting, and electronics. In every case, the functions and properties of the metallic nanostructures depend on both their composition and structure (i.e. size, shape, and spatial distribution). Among the challenges to the development of metal nanoparticles for these applications is the characterization of relationships between their structure and their functional properties over multiple structural degrees of freedom spanning a large range of values. In this work, a method for creating a morphological gradient of metal nanoparticles on a substrate is described. The approach, suited for high-throughput fabrication and characterization, is based on spinodal dewetting of a metallic thin film from its substrate. Through control of initial film thickness, anneal temperature, and anneal time, spinodal dewetting results in supported nanoparticles with well-defined and controlled structure. The approach is demonstrated through its application to preparation of Pd nanoparticles on a silicon nitride substrate. The morphologies of the particles were characterized by scanning electron and atomic force microscopies. Free energy-based stability and topological analyses were used to confirm the dewetting mechanism. In addition, the stability theory provides a connection to the thermophysical properties of the resulting nanoparticle array. The dewetting approach is general to any metal/support system and provides an alternative, inexpensive, and robust means to rapidly create metal nanostructures with control of morphology. It shows promise for large scale production of metal nanoparticles structures, as well as understanding basic stability properties of thin metal films. - Highlights: ► Pd dewetting from SiN occurs by a spinodal dewetting mechanism. ► Dewetting occurs at temperatures well below the melting point of Pd. ► Spinodal dewetting allows

Metal nanoparticles for microscopy and spectroscopy

NARCIS (Netherlands)

Zijlstra, P.; Orrit, M.; Koenderink, A.F.; Mello Donegá, de C.

2014-01-01

Metal nanoparticles interact strongly with light due to a resonant response of their free electrons. These ‘plasmon’ resonances appear as very strong extinction and scattering for particular wavelengths, and result in high enhancements of the local field compared to the incident electric field. In

Removal of heavy metals from aqueous solutions using Fe{sub 3}O{sub 4}, ZnO, and CuO nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Mahdavi, Shahriar, E-mail: smahdaviha@yahoo.com; Jalali, Mohsen, E-mail: jalali@basu.ac.ir [College of Agriculture, Bu-Ali Sina University, Department of Soil Science (Iran, Islamic Republic of); Afkhami, Abbas, E-mail: afkhami@basu.ac.ir [College of Chemistry, Bu-Ali Sina University, Department of Analytical Chemistry (Iran, Islamic Republic of)

2012-08-15

This study investigated the removal of Cd{sup 2+}, Cu{sup 2+}, Ni{sup 2+}, and Pb{sup 2+} from aqueous solutions with novel nanoparticle sorbents (Fe{sub 3}O{sub 4}, ZnO, and CuO) using a range of experimental approaches, including, pH, competing ions, sorbent masses, contact time, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The images showed that Fe{sub 3}O{sub 4}, ZnO, and CuO particles had mean diameters of about 50 nm (spheroid), 25 nm (rod shape), and 75 nm (spheroid), respectively. Tests were performed under batch conditions to determine the adsorption rate and uptake at equilibrium from single and multiple component solutions. The maximum uptake values (sum of four metals) in multiple component solutions were 360.6, 114.5, and 73.0 mg g{sup -1}, for ZnO, CuO, and Fe{sub 3}O{sub 4}, respectively. Based on the average metal removal by the three nanoparticles, the following order was determined for single component solutions: Cd{sup 2+} > Pb{sup 2+} > Cu{sup 2+} > Ni{sup 2+}, while the following order was determined in multiple component solutions: Pb{sup 2+} > Cu{sup 2+} > Cd{sup 2+} > Ni{sup 2+}. Sorption equilibrium isotherms could be described using the Freundlich model in some cases, whereas other isotherms did not follow this model. Furthermore, a pseudo-second order kinetic model was found to correctly describe the experimental data for all nanoparticles. Scanning electron microscopy, energy dispersive X-ray before and after metal sorption, and soil solution saturation indices showed that the main mechanism of sorption for Cd{sup 2+} and Pb{sup 2+} was adsorption, whereas both Cu{sup 2+} and Ni{sup 2+} sorption were due to adsorption and precipitation. These nanoparticles have potential for use as efficient sorbents for the removal of heavy metals from aqueous solutions and ZnO nanoparticles were identified as the most promising sorbent due to their high metal uptake.

Synthesis and antibacterial activity of water-dispersible silver nanoparticles via micellar nanoreactors

Science.gov (United States)

Pofali, Prasad; Shirolikar, Seema; Borde, Lalit; Pattani, Aditya; Dandekar, Prajakta; Jain, Ratnesh

2018-04-01

We have synthesized silver nanoparticles (AgNPs) using micelles of sugar fatty acid ester by dissolving the surfactant in a mixture of iso-octane and n-butanol, with solid-liquid extraction. Highly concentrated, water-dispersible AgNPs were obtained after thorough washing with alcohol, to remove excess of sucrose fatty acid ester DK SS and salt, followed by drying. The particles were characterized for their size, morphology and crystallinity using UV-Visible spectrophotometry, Transmission Electron Microscopy and x-ray diffractometry. Antibacterial study, confirmed the activity of nanoparticles against E. coli, P. aeruginosa and S. aureus, which causes diseases including diarrhoea and several life-threatening infections. Antibacterial activity of E. coli and P. aeruginosa was found to be 2.5 fold and for S. aureus 1.6 fold compared to 50 ppm conc. of Silver Nitrate. Our method of producing nanoparticles is employed as a platform technology for synthesizing other inorganic nanoparticles. This is the first report discussing the use of micellar carriers for obtaining silver nanopowder, to the best of our knowledge, which has the potential to overcome limitations during fabrication of AgNPs using reverse/inverse micelles. Our method yielded nano-sized, water-dispersible AgNPs via an easy and economic approach. The one-pot approach possesses advantages in terms of cost and simplicity, as compared with traditional methods of producing powdered AgNPs using energy intensive and expensive techniques like lyophilisation. The developed method, thus, possesses immense potential for commercial synthesis of AgNPs.

Ion-induced effects on metallic nanoparticles

International Nuclear Information System (INIS)

Klimmer, Andreas

2010-01-01

This work deals with the ion-irradiation of metallic nanoparticles in combination with various substrates. Particle diameters were systematically varied within the range of 2.5-14 nm, inter-particle distances range from 30-120 nm. Irradiations were performed with various inert gas ions with energies of 200 keV, resulting in an average ion range larger than the particle dimensions and therefore the effects of irradiation are mainly due to creation of structural defects within the particles and the underlying substrate as well. The main part of this work deals with ion-induced burrowing of metallic nanoparticles into the underlying substrate. The use of micellar nanoparticles with sharp size distribution combined with AFM and TEM analysis allows a much more detailed look at this effect than other works on that topic so far. With respect to the particle properties also a detailed look on the effect of irradiation on the particle structure would be interesting, which might lead to a deliberate influence on magnetic properties, for example. Within the context of this work, first successful experiments were performed on FePt particles, showing a significant reduction of the ordering temperature leading to the magnetically interesting, ordered L1 0 phase. (orig.)

Study of Coating Geometries and Photoluminescence Properties of Metal Nanoparticles/Graphite Composites

Directory of Open Access Journals (Sweden)

Pasquale Barone

2014-01-01

Full Text Available In this work we present the results of a study of growth and characterization of metal nanoparticles (Ag, Au, and Co/carbon surfaces. The nanoparticles grew by laser ablation technique and their dimensions were controlled by light scattering study and AFM microscopy before their insertion on graphite surface. Nanoparticles appear randomly disposed on carbon surfaces aggregating to form big particles only in the case of silver. The different behavior of metal nanoparticles on carbon surface was explained in terms of different metal wetting of surface, in agreement with previous theoretical results of He et al. Chemical information, obtained by X-ray photoelectron spectroscopy, indicated that the doping process is a simple physisorption while the interfacial interaction between particles and carbon layers causes local defects in graphite structure and the appearance of a strong photoluminescence signal for all composites. Moreover, the visible optical absorption decreases about 10% indicating the progressive metallization of carbon surface.

Facile preparation of superhydrophobic surfaces based on metal oxide nanoparticles

Science.gov (United States)

Bao, Xue-Mei; Cui, Jin-Feng; Sun, Han-Xue; Liang, Wei-Dong; Zhu, Zhao-Qi; An, Jin; Yang, Bao-Ping; La, Pei-Qing; Li, An

2014-06-01

A novel method for fabrication of superhydrophobic surfaces was developed by facile coating various metal oxide nanoparticles, including ZnO, Al2O3 and Fe3O4, on various substrates followed by treatment with polydimethylsiloxane (PDMS) via chemical vapor deposition (CVD) method. Using ZnO nanoparticles as a model, the changes in the surface chemical composition and crystalline structures of the metal oxide nanoparticles by PDMS treatment were investigated by X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The results show that the combination of the improved surface roughness generated from of the nanoparticles aggregation with the low surface-energy of silicon-coating originated from the thermal pyrolysis of PDMS would be responsible for the surface superhydrophobicity. By a simple dip-coating method, we show that the metal oxide nanoparticles can be easily coated onto the surfaces of various textural and dimensional substrates, including glass slide, paper, fabric or sponge, for preparation of superhydrophobic surfaces for different purpose. The present strategy may provide an inexpensive and new route to surperhydrophobic surfaces, which would be of technological significance for various practical applications especially for separation of oils or organic contaminates from water.

Facile preparation of superhydrophobic surfaces based on metal oxide nanoparticles

International Nuclear Information System (INIS)

Bao, Xue-Mei; Cui, Jin-Feng; Sun, Han-Xue; Liang, Wei-Dong; Zhu, Zhao-Qi; An, Jin; Yang, Bao-Ping; La, Pei-Qing; Li, An

2014-01-01

A novel method for fabrication of superhydrophobic surfaces was developed by facile coating various metal oxide nanoparticles, including ZnO, Al 2 O 3 and Fe 3 O 4 , on various substrates followed by treatment with polydimethylsiloxane (PDMS) via chemical vapor deposition (CVD) method. Using ZnO nanoparticles as a model, the changes in the surface chemical composition and crystalline structures of the metal oxide nanoparticles by PDMS treatment were investigated by X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The results show that the combination of the improved surface roughness generated from of the nanoparticles aggregation with the low surface-energy of silicon-coating originated from the thermal pyrolysis of PDMS would be responsible for the surface superhydrophobicity. By a simple dip-coating method, we show that the metal oxide nanoparticles can be easily coated onto the surfaces of various textural and dimensional substrates, including glass slide, paper, fabric or sponge, for preparation of superhydrophobic surfaces for different purpose. The present strategy may provide an inexpensive and new route to surperhydrophobic surfaces, which would be of technological significance for various practical applications especially for separation of oils or organic contaminates from water.

Facile preparation of superhydrophobic surfaces based on metal oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Bao, Xue-Mei; Cui, Jin-Feng; Sun, Han-Xue; Liang, Wei-Dong; Zhu, Zhao-Qi; An, Jin; Yang, Bao-Ping; La, Pei-Qing; Li, An, E-mail: lian2010@lut.cn

2014-06-01

A novel method for fabrication of superhydrophobic surfaces was developed by facile coating various metal oxide nanoparticles, including ZnO, Al{sub 2}O{sub 3} and Fe{sub 3}O{sub 4}, on various substrates followed by treatment with polydimethylsiloxane (PDMS) via chemical vapor deposition (CVD) method. Using ZnO nanoparticles as a model, the changes in the surface chemical composition and crystalline structures of the metal oxide nanoparticles by PDMS treatment were investigated by X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The results show that the combination of the improved surface roughness generated from of the nanoparticles aggregation with the low surface-energy of silicon-coating originated from the thermal pyrolysis of PDMS would be responsible for the surface superhydrophobicity. By a simple dip-coating method, we show that the metal oxide nanoparticles can be easily coated onto the surfaces of various textural and dimensional substrates, including glass slide, paper, fabric or sponge, for preparation of superhydrophobic surfaces for different purpose. The present strategy may provide an inexpensive and new route to surperhydrophobic surfaces, which would be of technological significance for various practical applications especially for separation of oils or organic contaminates from water.

Flame spray synthesis under a non-oxidizing atmosphere: Preparation of metallic bismuth nanoparticles and nanocrystalline bulk bismuth metal

Energy Technology Data Exchange (ETDEWEB)

Grass, Robert N.; Stark, Wendelin J. [Institute for Chemical and Bioengineering, ETH Zuerich (Switzerland)], E-mail: wendelin.stark@chem.ethz.ch

2006-10-15

Metallic bismuth nanoparticles of over 98% purity were prepared by a modified flame spray synthesis method in an inert atmosphere by oxygen-deficient combustion of a bismuth-carboxylate based precursor. The samples were characterized by X-ray diffraction, thermal analysis and scanning electron microscopy confirming the formation of pure, crystalline metallic bismuth nanoparticles. Compression of the as-prepared powder resulted in highly dense, nanocrystalline pills with strong electrical conductivity and bright metallic gloss.

Ferrofluid synthesis using oleic acid coated Fe3O4 nanoparticles dispersed in mineral oil for heat transfer applications

Science.gov (United States)

Imran, Mohd; Rahman Ansari, Akhalakur; Hussain Shaik, Aabid; Abdulaziz; Hussain, Shahir; Khan, Afzal; Rehaan Chandan, Mohammed

2018-03-01

Ferrofluids are stable dispersion of iron oxide nanoparticles in a carrier fluid which find potential applications in heat transfer. Fe3O4 nanoparticles of mean size in the range of 5–10 nm were synthesized using conventional co-precipitation method. This work deals with the synthesis of ferrofluids using mineral oil as a carrier fluid and oleic acid coated Fe3O4 nanoparticles as dispersed phase. Morphology (shape and size) and crystallinity of the synthesized nanoparticle is captured using TEM and XRD. Oleic acid coating on nanoparticle is probed using FTIR for confirming the stability of ferrofluid. Thermal properties of mineral oil based ferrofluid with varying concentration of nanoparticles are evaluated in terms of thermal conductivity. It was found that the thermal conductivity of ferrofluid increases upto 2.5% (w/v) nanoparticle loading, where a maximum enhancement of ∼51% in thermal conductivity was recorded as compared to the base fluid.

Stabilization of silica nanoparticles dispersions by surface modification with silicon derivative of thiacalix[4]arene

Energy Technology Data Exchange (ETDEWEB)

Gorbachuk, Vladimir V.; Ziatdinova, Ramilia V. [Kazan Federal University, A.M. Butlerov’ Chemical Institute (Russian Federation); Evtugyn, Vladimir G. [Kazan Federal University, Interdisciplinary Centre for Analytical Microscopy (Russian Federation); Stoikov, Ivan I., E-mail: ivan.stoikov@mail.ru [Kazan Federal University, A.M. Butlerov’ Chemical Institute (Russian Federation)

2015-03-15

For the first time, silica nanopowder functionalized with thiacalixarene derivatives was synthesized by ultrasonication of nanoparticles (diameter 23.7 ± 2.4 nm) with organosilicon derivative of thiacalixarene in glacial acetic acid. The protocol resulted in the formation of colloidal solution of low-disperse (polydispersity index of 0.11) submicron-sized (diameter 192.5 nm) clusters of nanoparticles according to the dynamic light scattering data. As defined by scanning electron microscopy (SEM), mean diameter of thiacalixarene-functionalized nanoparticles is equal to 25.5 ± 2.5 nm and the shape is close to spherical. SEM images confirm low aggregation of thiacalixarene-modified nanoparticle compared to initial silica nanopowder (mean diameter of aggregates 330 and 429 nm, correspondingly). According to the thermogravimetry/differential scanning calorimetry and elemental analysis of the nanoparticles obtained, 5 % of the powder mass was related to thiacalixarene units. The effect of thiacalixarene functionalization of silica nanoparticles on linear polydimethylsiloxane (PDMS)—silica dispersions was modeled to achieve high resistance toward liquid media required for similar sol–gel prepared PDMS-based materials applied for solid-phase microextraction. In such a manner, the influence of thiacalixarene-modified nanofiller on thermal stability and resistance against polar organic solvents was estimated. Similarity of decomposition temperature of both thiacalixarene-functionalized nanoparticles and non-functionalized silica nanoparticles was found. Swelling/solubility behavior observed was related to partial dissolution of PDMS/silica (10 % mixture) in alcohols. Thiacalixarene-functionalized silica particles exerted significantly higher resistance of PDMS/silica composites toward alcohol solvents.

Stabilization of silica nanoparticles dispersions by surface modification with silicon derivative of thiacalix[4]arene

International Nuclear Information System (INIS)

Gorbachuk, Vladimir V.; Ziatdinova, Ramilia V.; Evtugyn, Vladimir G.; Stoikov, Ivan I.

2015-01-01

For the first time, silica nanopowder functionalized with thiacalixarene derivatives was synthesized by ultrasonication of nanoparticles (diameter 23.7 ± 2.4 nm) with organosilicon derivative of thiacalixarene in glacial acetic acid. The protocol resulted in the formation of colloidal solution of low-disperse (polydispersity index of 0.11) submicron-sized (diameter 192.5 nm) clusters of nanoparticles according to the dynamic light scattering data. As defined by scanning electron microscopy (SEM), mean diameter of thiacalixarene-functionalized nanoparticles is equal to 25.5 ± 2.5 nm and the shape is close to spherical. SEM images confirm low aggregation of thiacalixarene-modified nanoparticle compared to initial silica nanopowder (mean diameter of aggregates 330 and 429 nm, correspondingly). According to the thermogravimetry/differential scanning calorimetry and elemental analysis of the nanoparticles obtained, 5 % of the powder mass was related to thiacalixarene units. The effect of thiacalixarene functionalization of silica nanoparticles on linear polydimethylsiloxane (PDMS)—silica dispersions was modeled to achieve high resistance toward liquid media required for similar sol–gel prepared PDMS-based materials applied for solid-phase microextraction. In such a manner, the influence of thiacalixarene-modified nanofiller on thermal stability and resistance against polar organic solvents was estimated. Similarity of decomposition temperature of both thiacalixarene-functionalized nanoparticles and non-functionalized silica nanoparticles was found. Swelling/solubility behavior observed was related to partial dissolution of PDMS/silica (10 % mixture) in alcohols. Thiacalixarene-functionalized silica particles exerted significantly higher resistance of PDMS/silica composites toward alcohol solvents

Composite nanoparticles containing rare earth metal and methods of preparation thereof

Science.gov (United States)

Kandapallil, Binil Itty Ipe; Krishnan, Lakshmi; Johnson, Francis

2018-04-10

The present invention is directed to composite nanoparticles comprising a metal, a rare earth element, and, optionally, a complexing ligand. The invention is also directed to composite nanoparticles having a core-shell structure and to processes for preparation of composite nanoparticles of the invention.

Optimized dispersion of ZnO nanoparticles and antimicrobial activity against foodborne pathogens and spoilage microorganisms

Energy Technology Data Exchange (ETDEWEB)

Perez Espitia, Paula Judith; Ferreira Soares, Nilda de Fatima, E-mail: nfsoares1@gmail.com [Department of Food Technology, Federal University of Vicosa (Brazil); Teofilo, Reinaldo F. [Federal University of Vicosa, Department of Chemistry (Brazil); Vitor, Debora M.; Reis Coimbra, Jane Selia dos; Andrade, Nelio Jose de [Department of Food Technology, Federal University of Vicosa (Brazil); Sousa, Frederico B. de; Sinisterra, Ruben D. [Federal University of Minas Gerais, Department of Chemistry (Brazil); Medeiros, Eber Antonio Alves [Department of Food Technology, Federal University of Vicosa (Brazil)

2013-01-15

Single primary nanoparticles of zinc oxide (nanoZnO) tend to form particle collectives, resulting in loss of antimicrobial activity. This work studied the effects of probe sonication conditions: power, time, and the presence of a dispersing agent (Na{sub 4}P{sub 2}O{sub 7}), on the size of nanoZnO particles. NanoZnO dispersion was optimized by response surface methodology (RSM) and characterized by the zeta potential (ZP) technique. NanoZnO antimicrobial activity was investigated at different concentrations (1, 5, and 10 % w/w) against four foodborne pathogens and four spoilage microorganisms. The presence of the dispersing agent had a significant effect on the size of dispersed nanoZnO. Minimum size after sonication was 238 nm. An optimal dispersion condition was achieved at 200 W for 45 min of sonication in the presence of the dispersing agent. ZP analysis indicated that the ZnO nanoparticle surface charge was altered by the addition of the dispersing agent and changes in pH. At tested concentrations and optimal dispersion, nanoZnO had no antimicrobial activity against Pseudomonas aeruginosa, Lactobacillus plantarum, and Listeria monocytogenes. However, it did have antimicrobial activity against Escherichia coli, Salmonella choleraesuis, Staphylococcus aureus, Saccharomyces cerevisiae, and Aspergillus niger. Based on the exhibited antimicrobial activity of optimized nanoZnO against some foodborne pathogens and spoilage microorganisms, nanoZnO is a promising antimicrobial for food preservation with potential application for incorporation in polymers intended as food-contact surfaces.

Optimized dispersion of ZnO nanoparticles and antimicrobial activity against foodborne pathogens and spoilage microorganisms

International Nuclear Information System (INIS)

Perez Espitia, Paula Judith; Ferreira Soares, Nilda de Fátima; Teófilo, Reinaldo F.; Vitor, Débora M.; Reis Coimbra, Jane Sélia dos; Andrade, Nélio José de; Sousa, Frederico B. de; Sinisterra, Rubén D.; Medeiros, Eber Antonio Alves

2013-01-01

Single primary nanoparticles of zinc oxide (nanoZnO) tend to form particle collectives, resulting in loss of antimicrobial activity. This work studied the effects of probe sonication conditions: power, time, and the presence of a dispersing agent (Na 4 P 2 O 7 ), on the size of nanoZnO particles. NanoZnO dispersion was optimized by response surface methodology (RSM) and characterized by the zeta potential (ZP) technique. NanoZnO antimicrobial activity was investigated at different concentrations (1, 5, and 10 % w/w) against four foodborne pathogens and four spoilage microorganisms. The presence of the dispersing agent had a significant effect on the size of dispersed nanoZnO. Minimum size after sonication was 238 nm. An optimal dispersion condition was achieved at 200 W for 45 min of sonication in the presence of the dispersing agent. ZP analysis indicated that the ZnO nanoparticle surface charge was altered by the addition of the dispersing agent and changes in pH. At tested concentrations and optimal dispersion, nanoZnO had no antimicrobial activity against Pseudomonas aeruginosa, Lactobacillus plantarum, and Listeria monocytogenes. However, it did have antimicrobial activity against Escherichia coli, Salmonella choleraesuis, Staphylococcus aureus, Saccharomyces cerevisiae, and Aspergillus niger. Based on the exhibited antimicrobial activity of optimized nanoZnO against some foodborne pathogens and spoilage microorganisms, nanoZnO is a promising antimicrobial for food preservation with potential application for incorporation in polymers intended as food-contact surfaces.

Catalysis by metallic nanoparticles in solution: Thermosensitive microgels as nanoreactors

OpenAIRE

Roa, Rafael; Angioletti-Uberti, Stefano; Lu, Yan; Dzubiella, Joachim; Piazza, Francesco; Ballauff, Matthias

2018-01-01

Metallic nanoparticles have been used as catalysts for various reactions, and the huge literature on the subject is hard to overlook. In many applications, the nanoparticles must be affixed to a colloidal carrier for easy handling during catalysis. These "passive carriers" (e.g., dendrimers) serve for a controlled synthesis of the nanoparticles and prevent coagulation during catalysis. Recently, hybrids from nanoparticles and polymers have been developed that allow us to change the catalytic ...

Metal nanoparticles in liquid phase catalysis; from recent advances to future goals.

Science.gov (United States)

Zahmakıran, Mehmet; Ozkar, Saim

2011-09-01

Metal nanoparticles have attracted much attention over the last decade owing to their unique properties, different to their bulk counterparts, which pave the way for their application in different fields from materials science and engineering to biomedical applications. Of particular interest, the use of metal nanoparticles in catalysis has brought superior efficiency in terms of activity, selectivity and lifetime to heterogeneous catalysis. This article reviews the recent developments in the synthesis routes and the catalytic performance of metal nanoparticles depending on the solvent used for various organic and inorganic transformations. Additionally, we also discuss the prevalent complications and their possible solutions plus future prospects in the field of nanocatalysis.

Synthesis of colloids based on gold nanoparticles dispersed in castor oil

International Nuclear Information System (INIS)

Silva, E. C. da; Silva, M. G. A. da; Meneghetti, S. M. P.; Machado, G.; Alencar, M. A. R. C.; Hickmann, J. M.; Meneghetti, M. R.

2008-01-01

New colloidal solutions of gold nanoparticles (AuNP), using castor oil as a nontoxic organic dispersant agent, were prepared via three different methods. In all three cases, tetrachloroauric(III) acid was employed as the gold source. The colloids were characterized by UV-Vis spectroscopy and transmission electron microscopy (TEM). The AuNP produced by the three methods were quasispherical in shape, however with different average sizes. The individual characteristics of the nanoparticles presented in each colloidal system were also confirmed by observation of absorption maxima at different wavelengths of visible light. Each method of synthesis leads to colloids with different grades of stability with respect to particle agglomeration.

A general approach to mesoporous metal oxide microspheres loaded with noble metal nanoparticles

KAUST Repository

Jin, Zhao; Xiao, Manda; Bao, Zhihong; Wang, Peng; Wang, Jianfang

2012-01-01

Catalytic microspheres: A general approach is demonstrated for the facile preparation of mesoporous metal oxide microspheres loaded with noble metal nanoparticles (see TEM image in the picture). Among 18 oxide/noble metal catalysts, TiO 2/0.1 mol Pd microspheres showed the highest turnover frequency in NaBH 4 reduction of 4-nitrophenol (see picture). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A general approach to mesoporous metal oxide microspheres loaded with noble metal nanoparticles

KAUST Repository

Jin, Zhao

2012-04-26

Catalytic microspheres: A general approach is demonstrated for the facile preparation of mesoporous metal oxide microspheres loaded with noble metal nanoparticles (see TEM image in the picture). Among 18 oxide/noble metal catalysts, TiO 2/0.1 mol Pd microspheres showed the highest turnover frequency in NaBH 4 reduction of 4-nitrophenol (see picture). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Penetration of nanoparticles in flax (Linum usitatissimum L.) calli and regenerants.

Science.gov (United States)

Kokina, Inese; Gerbreders, Vjačeslavs; Sledevskis, Eriks; Bulanovs, Andrejs

2013-05-20

We demonstrate a method for direct delivery of metal nanoparticles to flax calli and regenerant cells by vacuum deposition of metal nanolayers on powdered hormone followed by dispersal of the combined hormone-metal in medium. The penetration and location of the gold (AuNPs) and silver (AgNPs) nanoparticles in calli and in plant regenerants were confirmed by optical absorption spectroscopy and scanning electron microscopy. We detected a significant effect of the AuNPs and AgNPs on the regeneration type of flax calli. Copyright © 2013 Elsevier B.V. All rights reserved.

Green and Rapid Synthesis of Anticancerous Silver Nanoparticles by Saccharomyces boulardii and Insight into Mechanism of Nanoparticle Synthesis

Directory of Open Access Journals (Sweden)

Abhishek Kaler

2013-01-01

Full Text Available Rapidly developing field of nanobiotechnology dealing with metallic nanoparticle (MNP synthesis is primarily lacking control over size, shape, dispersity, yield, and reaction time. Present work describes an ecofriendly method for the synthesis of silver nanoparticles (AgNPs by cell free extract (CFE of Saccharomyces boulardii. Parameters such as culture age (stationary phase growth, cell mass concentration (400 mg/mL, temperature (35°C, and reaction time (4 h, have been optimized to exercise a control over the yield of nanoparticles and their properties. Nanoparticle (NP formation was confirmed by UV-Vis spectroscopy, elemental composition by EDX (energy dispersive X-rays analysis, and size and shape by transmission electron microscopy. Synthesized nanoparticles had the size range of 3–10 nm with high negative zeta potential (−31 mV indicating excellent stability. Role of proteins/peptides in NP formation and their stability were also elucidated. Finally, anticancer activity of silver nanoparticles as compared to silver ions was determined on breast cancer cell lines.

A new methodology for studying nanoparticle interactions in biological systems: Dispersing titania in biocompatible media using chemical stabilisers

Science.gov (United States)

Ramirez-Garcia, Sonia; Chen, Lan; Morris, Michael A.; Dawson, Kenneth A.

2011-11-01

We report here a highly successful and original protocol for the dispersion of nanoparticles in biocompatible fluids for in vitro and in vivo studies of the nanoparticle-biology interaction. Titania is chosen as a suitable model as it is one of the priority materials listed by the OECD and small particles of the anatase structure are extensively used as e.g. photocatalysts in solar cells. Consequently, its delivery into the environment and its interaction with biological organisms is unavoidable. Therefore, its biological effect needs to be understood. In this work, we prepared stable nanoparticle dispersions of anatase aggregates using citrate stabilisations between 45 and 55 nm at concentrations of up to 10 mg mL-1. The optimum pH for this type of suspension was 7, resulting in ζ-potentials of approximately -50 mV. The stabilised aggregates were the subject of dialysis to produce stable dispersions without the chemical stabiliser, thus allowing studies in the absence of potentially toxic chemicals. Different sizing techniques such as Dynamic Light Scattering (DLS), Nanoparticle Tracking Analysis (NTA) and Differential Centrifuge Sedimentation (DCS) were used to characterise the different suspensions. The results obtained with each of these techniques are compared and a critical analysis of the suitability of each technique is given.We report here a highly successful and original protocol for the dispersion of nanoparticles in biocompatible fluids for in vitro and in vivo studies of the nanoparticle-biology interaction. Titania is chosen as a suitable model as it is one of the priority materials listed by the OECD and small particles of the anatase structure are extensively used as e.g. photocatalysts in solar cells. Consequently, its delivery into the environment and its interaction with biological organisms is unavoidable. Therefore, its biological effect needs to be understood. In this work, we prepared stable nanoparticle dispersions of anatase aggregates

Oxide nanoparticles in an Al-alloyed oxide dispersion strengthened steel: crystallographic structure and interface with ferrite matrix

DEFF Research Database (Denmark)

Zhang, Zhenbo; Pantleon, Wolfgang

2017-01-01

Oxide nanoparticles are quintessential for ensuring the extraordinary properties of oxide dispersion strengthened (ODS) steels. In this study, the crystallographic structure of oxide nanoparticles, and their interface with the ferritic steel matrix in an Al-alloyed ODS steel, i.e. PM2000, were...

Direct observation of enhanced magnetism in individual size- and shape-selected 3 d transition metal nanoparticles

Science.gov (United States)

Kleibert, Armin; Balan, Ana; Yanes, Rocio; Derlet, Peter M.; Vaz, C. A. F.; Timm, Martin; Fraile Rodríguez, Arantxa; Béché, Armand; Verbeeck, Jo; Dhaka, R. S.; Radovic, Milan; Nowak, Ulrich; Nolting, Frithjof

2017-05-01

Magnetic nanoparticles are critical building blocks for future technologies ranging from nanomedicine to spintronics. Many related applications require nanoparticles with tailored magnetic properties. However, despite significant efforts undertaken towards this goal, a broad and poorly understood dispersion of magnetic properties is reported, even within monodisperse samples of the canonical ferromagnetic 3 d transition metals. We address this issue by investigating the magnetism of a large number of size- and shape-selected, individual nanoparticles of Fe, Co, and Ni using a unique set of complementary characterization techniques. At room temperature, only superparamagnetic behavior is observed in our experiments for all Ni nanoparticles within the investigated sizes, which range from 8 to 20 nm. However, Fe and Co nanoparticles can exist in two distinct magnetic states at any size in this range: (i) a superparamagnetic state, as expected from the bulk and surface anisotropies known for the respective materials and as observed for Ni, and (ii) a state with unexpected stable magnetization at room temperature. This striking state is assigned to significant modifications of the magnetic properties arising from metastable lattice defects in the core of the nanoparticles, as concluded by calculations and atomic structural characterization. Also related with the structural defects, we find that the magnetic state of Fe and Co nanoparticles can be tuned by thermal treatment enabling one to tailor their magnetic properties for applications. This paper demonstrates the importance of complementary single particle investigations for a better understanding of nanoparticle magnetism and for full exploration of their potential for applications.

A comparison of dispersing media for various engineered carbon nanoparticles

Directory of Open Access Journals (Sweden)

Holian Andrij

2007-07-01

Full Text Available Abstract Background With the increased manufacture and use of carbon nanoparticles (CNP there has been increasing concern about the potential toxicity of fugitive CNP in the workplace and ambient environment. To address this matter a number of investigators have conducted in vitro and in vivo toxicity assessments. However, a variety of different approaches for suspension of these particles (culture media, Tween 80, dimethyl sulfoxide, phosphate-buffered saline, fetal calf serum, and others, and different sources of materials have generated potentially conflicting outcomes. The quality of the dispersion of nanoparticles is very dependent on the medium used to suspend them, and this then will most likely affect the biological outcomes. Results In this work, the distributions of different CNP (sources and types have been characterized in various media. Furthermore, the outcome of instilling the different agglomerates, or size distributions, was examined in mouse lungs after one and seven days. Our results demonstrated that CNP suspended in serum produced particle suspensions with the fewest large agglomerates, and the most uniform distribution in mouse lungs. In addition, no apparent clearance of instilled CNP took place from lungs even after seven days. Conclusion This work demonstrates that CNP agglomerates are present in all dispersing vehicles to some degree. The vehicle that contains some protein, lipid or protein/lipid component disperses the CNP best, producing fewer large CNP agglomerates. In contrast, vehicles absent of lipid and protein produce the largest CNP agglomerates. The source of the CNP is also a factor in the degree of particle agglomeration within the same vehicle.

Photoactivable caps for reactive metal nanoparticles

Science.gov (United States)

Patel, Ashish

The synthesis and stabilization of reactive metal nanoparticles is often challenging under normal atmospheric conditions. This problem can be alleviated by capping and passivation. Our lab has focused on forming polymer coatings on the surface of reactive metal nanoparticles. We discovered a convenient and effective route for stabilization of aluminum nanoparticles (Al NPs), which uses the nascent metal core as a polymerization initiator for various organic monomers. In our previous work, we used this method to passivate the Al NPs using variety of epoxides and copolymers of epoxides and alkenes. These products have demonstrated air stability for weeks to months with little to no degradation in the active Al content. Since our previously synthesized Al NP's were not beneficial for rapid and efficient thermodynamic access to the active Al core, our goal was find polymers that could easily be photochemically activated to enhance such access. Since poly(methyl methacrylate) (PMMA) has photodegrading properties, we used PMMA as a capping agent to passivate Al NPs. In this work, we present capping and stabilization of Al NPs with PMMA, and also with 1,2-epoxyhexane/ PMMA. In our previous work, we increased the stability of Al NP capped with 1,2-epoxy-9-decene by adding 1,13-tetradecadiene as a cross-linker. Here, we used the methyl methacrylate (MMA) monomer as cross-linker for Al NP capped with 1,2-epoxy-9-decene. We have also used the MMA as capping agent. We use powder x-ray diffractametry (PXRD), differential scanning calorimetry (DSC), and thermogravity analysis (TGA) to confirm the presence of elemental Al and ATR-FTIR to confirm the presence of polymers.

DNA Modified with Metal Nanoparticles: Preparation and Characterization of Ordered Metal-DNA Nanostructures in a Solution and on a Substrate

Directory of Open Access Journals (Sweden)

Nina Kasyanenko

2016-01-01

Full Text Available DNA interaction with silver and aluminum nanoparticles in a solution has been investigated with the AFM, SEM, dynamic light scattering, viscometry, and spectral methods. The comparison of DNA interaction with nanoparticles synthesized by the reduction of Ag+ ions and with nanoparticles obtained by the electric discharge plasma method was done. DNA metallization in a solution and on n-silicon surface with metal nanoparticles or by the reduction of silver ions after their binding to DNA was executed and studied. It was shown that DNA strands with regular location of silver or aluminum nanoparticles can be prepared. The conditions for the formation of silver nanoparticles and silver nanoclusters on DNA were analyzed.

Formation of uranium based nanoparticles via gamma-irradiation

Energy Technology Data Exchange (ETDEWEB)

Nenoff, Tina M., E-mail: tmnenof@sandia.gov [Nanoscale Sciences Department, Sandia National Laboratories, P.O. Box 5800, MS-1415, Albuquerque, NM 87185 (United States); Ferriera, Summer R. [Nanoscale Sciences Department, Sandia National Laboratories, P.O. Box 5800, MS-1415, Albuquerque, NM 87185 (United States); Huang, Jianyu [Center for Integrated Nanotechnology, Sandia National Laboratories, P.O. Box 5800, MS-1315, Albuquerque, NM 87185 (United States); Hanson, Donald J. [Department of Hot Cells and Gamma Facilities, Sandia National Laboratories, P.O. Box 5800, MS-1143, Albuquerque, NM 87185 (United States)

2013-11-15

Graphical abstract: TEM image of d-U nanoparticles formed in aqueous solution by gamma irradiation. Display Omitted -- Highlights: •d-U nanoparticles were grown in solution by gamma irradiation. •The reaction solution does not exceed 25 °C (room temperature). •Only after multiday exposure to air is there evidence of oxidation of the d-U nanoparticles. •Evidence of d-U alloy nanoparticle formation confirmed by TEM/energy-dispersive X-ray (EDS) analysis. -- Abstract: The ability to fabricate nuclear fuels at low temperatures allows for the production of complex Uranium metal and alloys with minimum volatility of alloy components in the process. Gamma irradiation is a valuable method for the synthesis of a wide range of metal-based nanoparticles. We report on the synthesis via room temperature radiolysis and characterization of uranium (depleted, d-U) metal and uranium–lathanide (d-ULn, Ln = lanthanide surrogates) alloy nanoparticles from aqueous acidic salt solutions. The lanthanide surrogates chosen include La and Eu due to their similarity in ionic size and charge in solution. Detailed characterization results including UV–vis, TEM/HR-TEM, and single particle EDX (elemental analyses) are presented for the room temperature formed nanoparticle products.

Formation of uranium based nanoparticles via gamma-irradiation

International Nuclear Information System (INIS)

Nenoff, Tina M.; Ferriera, Summer R.; Huang, Jianyu; Hanson, Donald J.

2013-01-01

Graphical abstract: TEM image of d-U nanoparticles formed in aqueous solution by gamma irradiation. Display Omitted -- Highlights: •d-U nanoparticles were grown in solution by gamma irradiation. •The reaction solution does not exceed 25 °C (room temperature). •Only after multiday exposure to air is there evidence of oxidation of the d-U nanoparticles. •Evidence of d-U alloy nanoparticle formation confirmed by TEM/energy-dispersive X-ray (EDS) analysis. -- Abstract: The ability to fabricate nuclear fuels at low temperatures allows for the production of complex Uranium metal and alloys with minimum volatility of alloy components in the process. Gamma irradiation is a valuable method for the synthesis of a wide range of metal-based nanoparticles. We report on the synthesis via room temperature radiolysis and characterization of uranium (depleted, d-U) metal and uranium–lathanide (d-ULn, Ln = lanthanide surrogates) alloy nanoparticles from aqueous acidic salt solutions. The lanthanide surrogates chosen include La and Eu due to their similarity in ionic size and charge in solution. Detailed characterization results including UV–vis, TEM/HR-TEM, and single particle EDX (elemental analyses) are presented for the room temperature formed nanoparticle products

Metal Nanoparticles Supported on Al-MCM-41 via In Situ Aqueous Synthesis

International Nuclear Information System (INIS)

Alonso-Lemus, I.; Aguilar-Elguezabal, A.; Alvarez-Contreras, L.; Verde-Gomez, Y.

2010-01-01

MCM-41 have been used to custom synthesize catalysts in because of the controllable properties, such as pore size, active phase incorporation, crystal size, and morphology, among others. In this paper, a simple and versatile method for the incorporation of platinum, ruthenium, and palladium onto Al-MCM-41 mesoporous silica by direct inclusion of various precursors was studied. M/Al-MCM-41 structure, textural properties, morphology, and elemental composition were analyzed. The results obtained indicate that the Al-MCM-41 mesoporous-ordered structure was not affected by metallic particle incorporation. High-surface areas were obtained (1131 m2/g). Metallic nanoparticles dispersion on Al-MCM-41 was homogeneous for all samples and its particles sizes were between 6?nm to 20 nm. Microscopy results show round shape particles in platinum and palladium samples; however, ruthenium catalysts exhibit a spherical and rod shapes. Electrochemical testing for Pt/Al-MCM-41 showed electrocatalytic activity for H2 oxidation which indicates that these materials can be used as a catalyst in electrochemical devices.

Facile synthesis of Curcuma longa tuber powder engineered metal nanoparticles for bioimaging applications

Science.gov (United States)

Sankar, Renu; Rahman, Pattanathu K. S. M.; Varunkumar, Krishnamoorthy; Anusha, Chidambaram; Kalaiarasi, Arunachalam; Shivashangari, Kanchi Subramanian; Ravikumar, Vilwanathan

2017-02-01

Nanomaterials based fluorescent agents are rapidly becoming significant and promising transformative tools for improving medical diagnostics for extensive in vivo imaging modalities. Compared with conventional fluorescent agents, nano-fluorescence has capabilities to improve the in vivo detection and enriched targeting efficiencies. In our laboratory we synthesized fluorescent metal nanoparticles of silver, copper and iron using Curcuma longa tuber powder by simple reduction. The physicochemical properties of the synthesized metal nanoparticles were attained using UV-visible spectrophotometry, scanning electron microscopy with EDAX spectroscopy, dynamic light scattering, Fourier-transform infrared spectroscopy and X-ray diffraction. The Curcuma longa tuber powder has one of the bioactive compound Curcumin might act as a capping agent during the synthesis of nanoparticles. The synthesized metal nanoparticles fluorescence property was confirmed by spectrofluorometry. When compared with copper and iron nanoparticles the silver nanoparticles showed high fluorescence intensity under spectrofluorometry. Moreover, in vitro cell images of the silver nanoparticles in A549 cell lines also correlated with the results of spectrofluorometry. These silver nanoparticles show inspiring cell-imaging applications. They enter into cells without any further modifications, and the fluorescence property can be utilized for fluorescence-based cell imaging applications.

The origin of enhanced optical absorption in solar cells with metal nanoparticles embedded in the active layer

KAUST Repository

Lee, Jung-Yong

2010-04-29

We analyze the enhancement in optical absorption of an absorbing medium when spherical metal nanoparticles are embedded in it. Our analysis uses generalized Mie theory to calculate the absorbed optical power as a function of the distance from the metal nanoparticle. This analysis is used to evaluate the potential of enhancing optical absorption in thin-film solar cells by embedding spherical metal nanoparticles. We consider the trade-off between maximizing overall optical absorption and ensuring that a large fraction of the incident optical power is dissipated in the absorbing host medium rather than in the metal nanoparticle. We show that enhanced optical absorption results from strong scattering by the metal nanoparticle which locally enhances the optical electric fields. We also discuss the effect of a thin dielectric encapsulation of the metal nanoparticles. ©2010 Optical Society of America.

The origin of enhanced optical absorption in solar cells with metal nanoparticles embedded in the active layer

KAUST Repository

Lee, Jung-Yong; Peumans, Peter

2010-01-01

We analyze the enhancement in optical absorption of an absorbing medium when spherical metal nanoparticles are embedded in it. Our analysis uses generalized Mie theory to calculate the absorbed optical power as a function of the distance from the metal nanoparticle. This analysis is used to evaluate the potential of enhancing optical absorption in thin-film solar cells by embedding spherical metal nanoparticles. We consider the trade-off between maximizing overall optical absorption and ensuring that a large fraction of the incident optical power is dissipated in the absorbing host medium rather than in the metal nanoparticle. We show that enhanced optical absorption results from strong scattering by the metal nanoparticle which locally enhances the optical electric fields. We also discuss the effect of a thin dielectric encapsulation of the metal nanoparticles. ©2010 Optical Society of America.

Spectroscopic and magnetic studies of highly dispersible superparamagnetic silica coated magnetite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Tadyszak, Krzysztof [NanoBioMedical Centre, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznań (Poland); Institute of Molecular Physics Polish Academy of Sciences, ul. Mariana Smo.luchowskiego 17, 60-179 Poznań (Poland); Kertmen, Ahmet, E-mail: ahmet.kertmen@pg.gda.pl [Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk (Poland); Coy, Emerson [NanoBioMedical Centre, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznań (Poland); Andruszkiewicz, Ryszard; Milewski, Sławomir [Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk (Poland); Kardava, Irakli; Scheibe, Błażej; Jurga, Stefan [NanoBioMedical Centre, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznań (Poland); Chybczyńska, Katarzyna, E-mail: katarzyna.chybczynska@ifmpan.poznan.pl [Institute of Molecular Physics Polish Academy of Sciences, ul. Mariana Smo.luchowskiego 17, 60-179 Poznań (Poland)

2017-07-01

Highlights: • Superparamagnetic core-shell nanoparticles of Fe{sub 2}O{sub 3}@Silica were obtained. • Magnetic response was studied by DC, AC magnetometry and EPR spectroscopy. • Nanoparticles show magnetite structure with a well-defined Verwey transition. • Samples show no inter particle magnetic interactions or agglomeration. - Abstract: Superparamagnetic behavior in aqueously well dispersible magnetite core-shell Fe{sub 3}O{sub 4}@SiO{sub 2} nanoparticles is presented. The magnetic properties of core-shell nanoparticles were measured with use of the DC, AC magnetometry and EPR spectroscopy. Particles where characterized by HR-TEM and Raman spectroscopy, showing a crystalline magnetic core of 11.5 ± 0.12 nm and an amorphous silica shell of 22 ± 1.5 nm in thickness. The DC, AC magnetic measurements confirmed the superparamagnetic nature of nanoparticles, additionally the EPR studies performed at much higher frequency than DC, AC magnetometry (9 GHz) have confirmed the paramagnetic nature of the nanoparticles. Our results show the excellent magnetic behavior of the particles with a clear magnetite structure, which are desirable properties for environmental remediation and biomedical applications.

SWAXS investigations on diffuse boundary nanostructures of metallic nanoparticles synthesized by electrical discharges

Energy Technology Data Exchange (ETDEWEB)

Guo, Xiaoai, E-mail: xiaoai.guo@kit.edu; Gutsche, Alexander; Nirschl, Hermann [Karlsruhe Institute of Technology, Institute for Mechanical Process Engineering and Mechanics (Germany)

2013-11-15

Metallic nanoparticles have attracted a particular interest in scientific research and industrial applications due to their unique size-dependent physical and chemical properties. An eco-friendly and cost-effective synthesis method called electrical discharge enables large scale production of metallic nanoparticles. Systematic investigations of such synthesized metallic nanoparticles help to optimize the synthesis process and improve the product quality. In this work, for the first time we have investigated the diffuse interfacial boundary nanostructures of the metallic nanoparticles, which were synthesized under different conditions by electrical glow and arc discharges in the carrier gas, by means of a small- and wide-angle X-ray scattering (SWAXS) technique using a laboratory X-ray source. Meanwhile, this unique SWAXS technique allows simultaneous study of the primary particle size, morphology, and crystallinity. The metallic nanoparticles (copper and nickel) under investigation cover a size range of 10–80 nm, and the determined thickness of the diffuse boundary nanostructured layer of metallic nanoparticles is in the range of 1–3 nm. The experimental results obtained by SWAXS were compared to the TEM/EDX observation and the XRD reference patterns from RRUFF database, and a good agreement was found. Our SWAXS investigations indicated that the existence of a diffuse nanostructured solid layer on the synthesized metallic nanoparticle surface causes a negative deviation of the scattering intensity (Ι∝q{sup -α}, α>4) from Porod’s law which corresponds to the case of ideal two-phase particle systems with sharp boundaries (Ι∝q{sup -α}, α=4) . This implies that the electron density profile is not sharp but changes gradually between two phases, and hence the exponent α is greater than four. Two electron density profile models, sigmoidal electron-density gradient model and linear electron-density gradient model, have been taken into account in

PROSPECTS OF MODIFICATION OF BALNEOLOGICAL REMEDIES WITH BIOGENEOUS METALLS NANOPARTICLES

Directory of Open Access Journals (Sweden)

M. B. Mamuchieva

2015-01-01

Full Text Available The article considers the issues of mineral waters modification with biogeneous metals nanoparticles, since they have extremely important meaning for human's organism and their production in green and biologically compliant form is hard to overestimate. Russian scientists discovered low toxicity of these nanomaterials. So the use of biogeneuos metals in form of nanoparticles allows lowering of their toxicity compared with its use in forms of ions.

Size characterization of metal oxide nanoparticles in commercial sunscreen products

Science.gov (United States)

Bairi, Venu Gopal; Lim, Jin-Hee; Fong, Andrew; Linder, Sean W.

2017-07-01

There is an increase in the usage of engineered metal oxide (TiO2 and ZnO) nanoparticles in commercial sunscreens due to their pleasing esthetics and greater sun protection efficiency. A number of studies have been done concerning the safety of nanoparticles in sunscreen products. In order to do the safety assessment, it is pertinent to develop novel analytical techniques to analyze these nanoparticles in commercial sunscreens. This study is focused on developing analytical techniques that can efficiently determine particle size of metal oxides present in the commercial sunscreens. To isolate the mineral UV filters from the organic matrices, specific procedures such as solvent extraction were identified. In addition, several solvents (hexane, chloroform, dichloromethane, and tetrahydrofuran) have been investigated. The solvent extraction using tetrahydrofuran worked well for all the samples investigated. The isolated nanoparticles were characterized by using several different techniques such as transmission electron microscopy, scanning electron microscopy, dynamic light scattering, differential centrifugal sedimentation, and x-ray diffraction. Elemental analysis mapping studies were performed to obtain individual chemical and morphological identities of the nanoparticles. Results from the electron microscopy techniques were compared against the bulk particle sizing techniques. All of the sunscreen products tested in this study were found to contain nanosized (≤100 nm) metal oxide particles with varied shapes and aspect ratios, and four among the 11 products were showed to have anatase TiO2.

Colloidal dispersions of maghemite nanoparticles produced by laser pyrolysis with application as NMR contrast agents

Energy Technology Data Exchange (ETDEWEB)

Veintemillas-Verdaguer, Sabino [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid (Spain); Morales, Maria del Puerto [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid (Spain); Bomati-Miguel, Oscar [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid (Spain); Bautista, Carmen [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid (Spain); Zhao, Xinqing [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid (Spain); Bonville, Pierre [CEA, CE Saclay, DSM/DRECAM/SPEC, 91191 Gif-Sur-Yvette (France); Alejo, Rigoberto Perez de [Universidad Complutense de Madrid, Unidad de RMN, Paseo Juan XXIII, 1, 28040 Madrid (Spain); Ruiz-Cabello, Jesus [Universidad Complutense de Madrid, Unidad de RMN, Paseo Juan XXIII, 1, 28040 Madrid (Spain); Santos, Martin [Hospital Universitario Puerta de Hierro, Servicio de Cirugia Experimental. C/San Martin de Porres 4, 28035 Madrid (Spain); Tendillo-Cortijo, Francisco J [Hospital Universitario Puerta de Hierro, Servicio de Cirugia Experimental. C/San Martin de Porres 4, 28035 Madrid (Spain); Ferreiros, Joaquin [Hospital Clinico de Madrid ' San Carlos' , Ciudad Universitaria, 28040 Madrid (Spain)

2004-08-07

Biocompatible magnetic dispersions have been prepared from {gamma}-Fe{sub 2}O{sub 3} nanoparticles (5 nm) synthesized by continuous laser pyrolysis of Fe(CO){sub 5} vapours. The feasibility of using these dispersions as magnetic resonance imaging (MRI) contrast agents has been analysed in terms of chemical structure, magnetic properties, {sup 1}H NMR relaxation times and biokinetics. The magnetic nanoparticles were dispersed in a strong alkaline solution in the presence of dextran, yielding stable colloids in a single step. The dispersions consist of particle-aggregates 25 nm in diameter measured using transmission electron microscope and a hydrodynamic diameter of 42 nm measured using photon correlation spectroscopy. The magnetic and relaxometric properties of the dispersions were of the same order of magnitude as those of commercial contrast agents produced using coprecipitation. However, these dispersions, when injected intravenously in rats at standard doses showed a mono-exponential blood clearance instead of a biexponential one, with a blood half-life of 7 {+-} 1 min. Furthermore, an important enhancement of the image contrast was observed after the injection, mainly located at the liver and the spleen of the rat. In conclusion, the laser pyrolysis technique seems to be a good alternative to the coprecipitation method for producing MRI contrast agents, with the advantage of being a continuous synthesis method that leads to very uniform particles capable of being dispersed and therefore transformed in a biocompatible magnetic liquid.

Microwave-induced synthesis of highly dispersed gold nanoparticles within the pore channels of mesoporous silica

International Nuclear Information System (INIS)

Gu Jinlou; Fan Wei; Shimojima, Atsushi; Okubo, Tatsuya

2008-01-01

Highly dispersed gold nanoparticles have been incorporated into the pore channels of SBA-15 mesoporous silica through a newly developed strategy assisted by microwave radiation (MR). The sizes of gold are effectively controlled attributed to the rapid and homogeneous nucleation, simultaneous propagation and termination of gold precursor by MR. Diol moieties with high dielectric and dielectric loss constants, and hence a high microwave activation, were firstly introduced to the pore channels of SBA-15 by a simple addition reaction between amino group and glycidiol and subsequently served as the reduction centers for gold nanoparticles. Extraction of the entrapped gold from the nanocomposite resulted in milligram quantities of gold nanoparticles with low dispersity. The successful assembly process of diol groups and formation of gold nanoparticles were monitored and tracked by solid-state NMR and UV-vis measurements. Characterization by small angle X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicated that the incorporation of gold nanoparticles would not breakup the structural integrity and long-range periodicity of SBA-15. The gold nanoparticles had a narrow size distribution with diameters in the size range of 5-10 nm through TEM observation. The average particles size is 7.9 nm via calculation by the Scherrer formula and TEM measurements. Nitrogen adsorption and desorption isotherms gave further evidence that the employed method was efficient and gold nanoparticles were successfully incorporated into the pore channels of SBA-15. - Graphical abstract: A facile and novel strategy has been developed to incorporate gold nanoparticles into the pore channels of mesoporous SBA-15 assisted by microwave radiation (MR) with mild reaction condition and rapid reaction speed. Due to the rapid and homogeneous nucleation, simultaneous propagation and termination by MR, the size of gold nanoparticles are effectively controlled

Dissolution of metal and metal oxide nanoparticles in aqueous media

International Nuclear Information System (INIS)

Odzak, Niksa; Kistler, David; Behra, Renata; Sigg, Laura

2014-01-01

The dissolution of Ag (citrate, gelatin, polyvinylpyrrolidone and chitosan coated), ZnO, CuO and carbon coated Cu nanoparticles (with two nominal sizes each) has been studied in artificial aqueous media, similar in chemistry to environmental waters, for up to 19 days. The dissolved fraction was determined using DGT (Diffusion Gradients in Thin films), dialysis membrane (DM) and ultrafiltration (UF). Relatively small fractions of Ag nanoparticles dissolved, whereas ZnO dissolved nearly completely within few hours. Cu and CuO dissolved as a function of pH. Using DGT, less dissolved Ag was measured compared to UF and DM, likely due to differences in diffusion of organic complexes. Similar dissolved metal concentrations of ZnO, Cu and CuO nanoparticles were determined using DGT and UF, but lower using DM. The results indicate that there is a need to apply complementary techniques to precisely determine dissolution of nanoparticles in aqueous media. - Highlights: • Three different techniques used simultaneously to measure NPs dissolution. • ZnO-NPs are the most soluble, followed by CuO-NPs, carbon coated Cu-NPs and Ag-NPs. • Dissolution is an important process affecting the fate of nanoparticles. • Complementary techniques are needed to precisely determine dissolution of NPs. - Dissolution of several types of nanoparticles was examined in aqueous media using three complementary techniques

Surface plasmon enhanced quantum transport in a hybrid metal nanoparticle array

International Nuclear Information System (INIS)

Sun, Lin; Nan, Yali; Xu, Shang; Zhang, Sishi; Han, Min

2014-01-01

Hybrid Pd–Ag nanoparticle arrays composed of randomly distributed Pd nanoparticles in dense packing and a small number of dispersed Ag nanoparticles were fabricated with controlled coverage. Photo-enhanced conductance was observed in the nanoparticle arrays. Largest enhancement, which can be higher than 20 folds, was obtained with 450 nm light illumination. This wavelength was found to correlate with the surface plasmon resonance of the Ag nanoparticles. Electron transport measurements showed there were significant Coulomb blockade in the nanoparticle arrays and the blockade could be overcome with the surface plasmon enhanced local field of Ag nanoparticles induced by light illumination. - Highlights: • We study photo-enhanced electron conductance of a hybrid Pd–Ag nanoparticle array. • The light-induced conductance enhancement is as high as 20 folds at 10 K. • The enhancement is correlate with the surface plasmon resonance of Ag nanoparticles. • Coulomb blockades is overcome with the surface plasmon enhanced local field

Systematic study of ligand structures of metal oxide EUV nanoparticle photoresists

KAUST Repository

Jiang, Jing

2015-03-19

Ligand stabilized metal oxide nanoparticle resists are promising candidates for EUV lithography due to their high sensitivity for high-resolution patterning and high etching resistance. As ligand exchange is responsible for the patterning mechanism, we systematically studied the influence of ligand structures of metal oxide EUV nanoparticles on their sensitivity and dissolution behavior. ZrO2 nanoparticles were protected with various aromatic ligands with electron withdrawing and electron donating groups. These nanoparticles have lower sensitivity compared to those with aliphatic ligands suggesting the structures of these ligands is more important than their pka on resist sensitivity. The influence of ligand structure was further studied by comparing the nanoparticles’ solubility for a single type ligand to mixtures of ligands. The mixture of nanoparticles showed improved pattern quality. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Cyclodextrin-grafted barium titanate nanoparticles for improved dispersion and stabilization in water-based systems

Energy Technology Data Exchange (ETDEWEB)

Serra-Gómez, R. [Universidad de Navarra, Departamento de Química y Edafología (Spain); Martinez-Tarifa, J. M. [Universidad Carlos III de Madrid, Departamento de Ingeniería Eléctrica (Spain); González-Benito, J. [Universidad Carlos III de Madrid, Departamento de Ciencia e Ingeniería de Materiales e Ingeniería Química, IQMAAB (Spain); González-Gaitano, G., E-mail: gaitano@unav.es [Universidad de Navarra, Departamento de Química y Edafología (Spain)

2016-01-15

Ceramic nanoparticles with piezoelectric properties, such as BaTiO{sub 3} (BT), constitute a promising approach in the fields of nanocomposite materials and biomaterials. In the latter case, to be successful in their preparation, the drawback of their fast aggregation and practically null stability in water has to be overcome. The objective of this investigation has been the surface functionalization of BaTiO{sub 3} nanoparticles with cyclodextrins (CDs) as a way to break the aggregation and improve the stability of the nanoparticles in water solution, preventing and minimizing their fast precipitation. As a secondary goal, we have achieved extra-functionality of the nanoparticles, bestowed from the hydrophobic cavity of the macrocycle, which is able to lodge guest molecules that can form inclusion complexes with the oligosaccharide. The nanoparticle functionalization has been fully tracked and characterized, and the cytotoxicity of the modified nanoparticles with fibroblasts and pre-osteoblasts cell lines has been assessed with excellent results in a wide range of concentrations. The modified nanoparticles were found to be suitable for the easy preparation of nanocomposite hydrogels, via dispersion in hydrophilic polymers of typical use in biomedical applications (PEG, Pluronics, and PEO), and further processed in the form of films via water casting, showing very good results in terms of homogeneity in the dispersion of the filler. Likewise, as examples of application and with the aim of exploring a different range of nanocomposites, rhodamine B was included in the macrocycles as a model molecule, and films prepared from a thermoplastic matrix (EVA) via high-energy ball milling have been tested by impedance spectroscopy to discuss their dielectric properties, which indicated that even small modifications in the surface of the nanoparticles generate a different kind of interaction with the polymeric matrix. The CD-modified nanoparticles are thus suitable for easy

A general mechanism for intracellular toxicity of metal-containing nanoparticles

Science.gov (United States)

Sabella, Stefania; Carney, Randy P.; Brunetti, Virgilio; Malvindi, Maria Ada; Al-Juffali, Noura; Vecchio, Giuseppe; Janes, Sam M.; Bakr, Osman M.; Cingolani, Roberto; Stellacci, Francesco; Pompa, Pier Paolo

2014-05-01

The assessment of the risks exerted by nanoparticles is a key challenge for academic, industrial, and regulatory communities worldwide. Experimental evidence points towards significant toxicity for a range of nanoparticles both in vitro and in vivo. Worldwide efforts aim at uncovering the underlying mechanisms for this toxicity. Here, we show that the intracellular ion release elicited by the acidic conditions of the lysosomal cellular compartment - where particles are abundantly internalized - is responsible for the cascading events associated with nanoparticles-induced intracellular toxicity. We call this mechanism a ``lysosome-enhanced Trojan horse effect'' since, in the case of nanoparticles, the protective cellular machinery designed to degrade foreign objects is actually responsible for their toxicity. To test our hypothesis, we compare the toxicity of similar gold particles whose main difference is in the internalization pathways. We show that particles known to pass directly through cell membranes become more toxic when modified so as to be mostly internalized by endocytosis. Furthermore, using experiments with chelating and lysosomotropic agents, we found that the toxicity mechanism for different metal containing NPs (such as metallic, metal oxide, and semiconductor NPs) is mainly associated with the release of the corresponding toxic ions. Finally, we show that particles unable to release toxic ions (such as stably coated NPs, or diamond and silica NPs) are not harmful to intracellular environments.The assessment of the risks exerted by nanoparticles is a key challenge for academic, industrial, and regulatory communities worldwide. Experimental evidence points towards significant toxicity for a range of nanoparticles both in vitro and in vivo. Worldwide efforts aim at uncovering the underlying mechanisms for this toxicity. Here, we show that the intracellular ion release elicited by the acidic conditions of the lysosomal cellular compartment - where

Solidification and Immobilization of Heavy metals in Soil using with nano-metallic Ca/CaO Dispersion Mixture

Directory of Open Access Journals (Sweden)

Mallampati S. R.

2013-04-01

Full Text Available In the present work, the use of nano-metallic calcium (Ca and calcium oxide (CaO dispersion mixture for the immobilization of heavy metals (As, Cd, Cr and Pb in soil was investigated. With simple grinding, 85-90% of heavy metals immobilization could be achieved, while it could be enhanced to 98-100% by grinding with the addition of nano-metallic Ca/CaO dispersion mixture. By SEM-EDS elemental maps as well as semi-quantitative analysis observed that the amount of As, Cd, Cr and Pb measurable on soil particle surface decreases after nano-metallic Ca/CaO treatment. The leachable heavy metals concentrations were reduced, to the concentration lower than the Japan soil elution standard regulatory threshold, i. e., < 0.01 mg/l for As, Cd and Pb and 0.05mg/l for Cr. Whereas, the effect of soil moisture and pH on heavy metals immobilization was not much influenced. The results suggest that nano-metallic Ca/CaO mixture is suitable to be used for the gentle immobilization of heavy metals contaminated soil at normal moisture conditions.

Simultaneous decontamination of cross-polluted soils with heavy metals and PCBs using a nano-metallic Ca/CaO dispersion mixture.

Science.gov (United States)

Mallampati, Srinivasa Reddy; Mitoma, Yoshiharu; Okuda, Tetsuji; Sakita, Shogo; Simion, Cristian

2014-01-01

In the present work, we investigated the use of nano-metallic calcium (Ca) and calcium oxide (CaO) dispersion mixture for the simultaneous remediation of contaminated soils with both heavy metals (As, Cd, Cr, and Pb) and polychlorinated biphenyls (PCBs). Regardless of soil moisture content, nano-metallic Ca/CaO dispersion mixture achieved about 95-99% of heavy metal immobilization by a simple grinding process. During the same treatment, reasonable PCB hydrodechlorination efficiencies were obtained (up to 97%), though higher hydrodechlorination efficiency by preliminary drying of soil was observed.

A Simple Method for Forming Hybrid Core-Shell Nanoparticles Suspended in Water

Directory of Open Access Journals (Sweden)

Jean-Christophe Daigle

2008-01-01

addition fragmentation chain transfer (RAFT polymerization as dispersant. Then, the resulting dispersion is engaged in a radical emulsion polymerization process whereby a hydrophobic organic monomer (styrene and butyl acrylate is polymerized to form the shell of the hybrid nanoparticle. This method is extremely versatile, allowing the preparation of a variety of nanocomposites with metal oxides (alumina, rutile, anatase, barium titanate, zirconia, copper oxide, metals (Mo, Zn, and even inorganic nitrides (Si3N4.

Metal nanoparticle film-based room temperature Coulomb transistor.

Science.gov (United States)

Willing, Svenja; Lehmann, Hauke; Volkmann, Mirjam; Klinke, Christian

2017-07-01

Single-electron transistors would represent an approach to developing less power-consuming microelectronic devices if room temperature operation and industry-compatible fabrication were possible. We present a concept based on stripes of small, self-assembled, colloidal, metal nanoparticles on a back-gate device architecture, which leads to well-defined and well-controllable transistor characteristics. This Coulomb transistor has three main advantages. By using the scalable Langmuir-Blodgett method, we combine high-quality chemically synthesized metal nanoparticles with standard lithography techniques. The resulting transistors show on/off ratios above 90%, reliable and sinusoidal Coulomb oscillations, and room temperature operation. Furthermore, this concept allows for versatile tuning of the device properties such as Coulomb energy gap and threshold voltage, as well as period, position, and strength of the oscillations.

A microscopic approach to Casimir and Casimir–Polder forces between metallic bodies

International Nuclear Information System (INIS)

Barcellona, Pablo; Passante, Roberto

2015-01-01

We consider the Casimir–Polder interaction energy between a metallic nanoparticle and a metallic plate, as well as the Casimir interaction energy between two macroscopic metal plates, in terms of the many-body dispersion interactions between their constituents. Expressions for two- and three-body dispersion interactions between the microscopic parts of a real metal are first obtained, both in the retarded and non-retarded limits. These expressions are then used to evaluate the overall two- and three-body contributions to the macroscopic Casimir–Polder and Casimir force, and to compare them with each other, for the two following geometries: metal nanoparticle/half-space and half-space/half-space, where all the materials are assumed perfect conductors. The above evaluation is obtained by summing up the contributions from the microscopic constituents of the bodies (metal nanoparticles). In the case of nanoparticle/half-space, our results fully agree with those that can be extracted from the corresponding macroscopic results, and explicitly show the non-applicability of the pairwise approximation for the geometry considered. In both cases, we find that, while the overall two-body contribution yields an attractive force, the overall three-body contribution is repulsive. Also, they turn out to be of the same order, consistently with the known non applicability of the pairwise approximation. The issue of the rapidity of convergence of the many-body expansion is also briefly discussed

Boosting catalytic activity of metal nanoparticles for 4-nitrophenol reduction: Modification of metal naoparticles with poly(diallyldimethylammonium chloride)

Energy Technology Data Exchange (ETDEWEB)

You, Jyun-Guo; Shanmugam, Chandirasekar [Department of Chemistry, National Sun Yat-sen University, Taiwan (China); Liu, Yao-Wen; Yu, Cheng-Ju [Department of Applied Physics and Chemistry, University of Taipei, Taiwan (China); Tseng, Wei-Lung, E-mail: tsengwl@mail.nsysu.edu.tw [Department of Chemistry, National Sun Yat-sen University, Taiwan (China); School of Pharmacy, College of Pharmacy, Kaohsiung Medical University, Taiwan (China); Center for Nanoscience and Nanotechnology, National Sun Yat-sen University, Taiwan (China)

2017-02-15

Highlights: • The choice of capping ligand determines catalytic activity of metal nanocatalysts. • PDDA-capped metal nanoparticles electrostatically interact with 4-NP and BH4{sup −}. • PDDA-capped metal nanoparticles have good recyclability and large scalability. • PDDA-capped Pd nanoparticles show the highest rate constant and activity parameter. - Abstract: Most of the previously reported studies have focused on the change in the size, morphology, and composition of metal nanocatalysts for improving their catalytic activity. Herein, we report poly(diallyldimethylammonium chloride) [PDDA]-stabilized nanoparticles (NPs) of platinum (Pt) and palladium (Pd) as highly active and efficient catalysts for hydrogenation of 4-nitrophenol (4-NP) in the presence of NaBH4. PDDA-stabilized Pt and Pd NPs possessed similar particle size and same facet with citrate-capped Pt and Pd NPs, making this study to investigate the inter-relationship between catalytic activity and surface ligand without the consideration of the effects of particle size and facet. Compared to citrate-capped Pt and Pd NPs, PDDA-stabilized Pt and Pd NPs exhibited excellent pH and salt stability. PDDA could serve as an electron acceptor for metal NPs to produce the net positive charges on the metal surface, which provide strong electrostatic attraction with negatively charged nitrophenolate and borohydride ions. The activity parameter and rate constant of PDDA-stabilized metal NPs were higher than those of citrate-capped metal NPs. Compared to the previously reported Pd nanomaterials for the catalysis of NaBH4-mediated reduction of 4-NP, PDDA-stabilized Pd NPs exhibited the extremely high activity parameter (195 s{sup −1} g{sup −1}) and provided excellent scalability and reusability.

Bacterial exposure to metal-oxide nanoparticles: Methods, physical interactions, and biological effects

Science.gov (United States)

Horst, Allison Marie

Nanotechnology is a major endeavor of this century, with proposed applications in fields ranging from agriculture to energy to medicine. Nanoscale titanium dioxide (nano-TiO2) is among the most widely produced nanoparticles worldwide, and already exists in consumer products including impermanent personal care products and surface coatings. Inevitably, nano-TiO2 will be transported into the environment via consumer or industrial waste, where its effects on organisms are largely unknown. Out of concern for the possible ill-effects of nanoparticles in the environment, there is now a field of study in nanotoxicology. Bacteria are ideal organisms for nanotoxicology research because they are environmentally important, respond rapidly to intoxication, and provide evidence for effects in higher organisms. My doctoral research focuses on the effects and interactions of nano-TiO2 in aqueous systems with planktonic bacteria. This dissertation describes four projects and the outcomes of the research: (1) A discovery, using a combination of environmental- and cryogenic-scanning electron microscopy and dynamic light scattering (DLS), that initially agglomerated nano-TiO2 is dispersed upon bacterial contact, as nanoparticles preferentially sorbed to cell surfaces. (2) Establishment of a method to disperse nanoparticles in an aqueous culture medium for nanotoxicology studies. A combination of electrostatic repulsion, steric hindrance and sonication yielded a high initial level of nano-TiO2 dispersion (i.e. E. coli growth and membrane processes. Together, this research is towards: better understanding outcomes of interactions between nanoparticles and bacteria, advancing methods in the relatively new field of nanotoxicology that are transferable to other nanoparticle and media chemistries, and improving our understanding of structure-activity relationships (e.g. size and doping effects) leading to intoxication in environmental organisms.

A Review on Metal Nanoparticles Nucleation and Growth on/in Graphene

Directory of Open Access Journals (Sweden)

Francesco Ruffino

2017-07-01

Full Text Available In this review, the fundamental aspects (with particular focus to the microscopic thermodynamics and kinetics mechanisms concerning the fabrication of graphene-metal nanoparticles composites are discussed. In particular, the attention is devoted to those fabrication methods involving vapor-phase depositions of metals on/in graphene-based materials. Graphene-metal nanoparticles composites are, nowadays, widely investigated both from a basic scientific and from several technological point of views. In fact, these graphene-based systems present wide-range tunable and functional electrical, optical, and mechanical properties which can be exploited for the design and production of innovative and high-efficiency devices. This research field is, so, a wide and multidisciplinary section in the nanotechnology field of study. So, this review aims to discuss, in a synthetic and systematic framework, the basic microscopic mechanisms and processes involved in metal nanoparticles formation on graphene sheets by physical vapor deposition methods and on their evolution by post-deposition processes. This is made by putting at the basis of the discussions some specific examples to draw insights on the common general physical and chemical properties and parameters involved in the synergistic interaction processes between graphene and metals.

Salt-Driven Deposition of Thermoresponsive Polymer-Coated Metal Nanoparticles on Solid Substrates.

Science.gov (United States)

Zhang, Zhiyue; Maji, Samarendra; da Fonseca Antunes, André B; De Rycke, Riet; Hoogenboom, Richard; De Geest, Bruno G

2016-06-13

Here we report on a simple, generally applicable method for depositing metal nanoparticles on a wide variety of solid surfaces under all aqueous conditions. Noble-metal nanoparticles obtained by citrate reduction followed by coating with thermoresponsive polymers spontaneously form a monolayer-like structure on a wide variety of substrates in presence of sodium chloride whereas this phenomenon does not occur in salt-free medium. Interestingly, this phenomenon occurs below the cloud point temperature of the polymers and we hypothesize that salt ion-induced screening of electrostatic charges on the nanoparticle surface entropically favors hydrophobic association between the polymer-coated nanoparticles and a hydrophobic substrate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metal nanoparticles (other than gold or silver) prepared using plant extracts for medical applications

Science.gov (United States)

Pasca, Roxana-Diana; Santa, Szabolcs; Racz, Levente Zsolt; Racz, Csaba Pal

2016-12-01

There are many modalities to prepare metal nanoparticles, but the reducing of the metal ions with plant extracts is one of the most promising because it is considerate less toxic for the environment, suitable for the use of those nanoparticles in vivo and not very expensive. Various metal ions have been already studied such as: cobalt, copper, iron, platinum, palladium, zinc, indium, manganese and mercury and the number of plant extracts used is continuously increasing. The prepared systems were characterized afterwards with a great number of methods of investigation: both spectroscopic (especially UV-Vis spectroscopy) and microscopic (in principal, electron microscopy-TEM) methods. The applications of the metal nanoparticles obtained are diverse and not completely known, but the medical applications of such nanoparticles occupy a central place, due to their nontoxic components, but some diverse industrial applications do not have to be forgotten.

Synthesis of self-assembly plasmonic silver nanoparticles with tunable luminescence color

International Nuclear Information System (INIS)

Al-Ghamdi, Haifa S.; Mahmoud, Waleed E.

2014-01-01

Assembly is an elegant and effective bottom-up approach to prepare arrays of nanoparticles from nobel metals. Noble metal nanoparticles are perfect building blocks because they can be prepared with an adequate functionalization to allow their assembly and with controlled sizes. Herein, we report a novel recipe for the synthesis of self-assembled silver nanoparticles with tunable optical properties and sizes. The synthetic route followed here based on the covalent binding among silver nanoparticles by means of poly vinyl alcohol for the first time. The size of silver nanoparticle is governed by varying the amount of sodium borohydride. The as-synthesized nanoparticles were characterized by transmission electron microscopy, x-ray diffraction, energy dispersive x-ray spectroscopy, selected area electron diffraction and UV–vis spectroscopy. Results depicted that self-assembly of mono-dispersed silver nanoparticles with different sizes have been achieved. The silver nanostructure has a single crystalline faced centered cubic structure with growth orientation along (1 1 1) facet. These nanoparticles exhibited localized surface plasmon resonance at 403 nm. The luminescence peaks were red-sifted from violet to green due to the increase of the particle sizes. -- Highlights: • Self-assembled silver nanoparticles based PVA were synthesized. • NaBH 4 amount was found particle size dependent. • Silver nanoparticles strongly affected the surface plasmon resonance. • Highly symmetric luminescence emission band narrow width is obtained. • Dark field image showed a tunable color change from violet to green

Enhancement of in-vitro drug dissolution of ketoconazole for its optimal in-vivo absorption using Nanoparticles and Solid Dispersion forms of the drug

Science.gov (United States)

Syed, Mohammed Irfan

Ketoconazole is one of the most widely prescribed oral antifungal drugs for the systemic treatment of various fungal infections. However, due its hydrophobic nature and poor solubility profiles in the gastro-intestinal fluids, variations in its bioavailability have been documented. Therefore, to enhance its dissolution in the biological fluids, this study was initiated to develop and evaluate Nanoparticles and Solid Dispersion forms of the drug. Nanoparticles of ketoconazole were developed by Wet Bead Milling technique using PVP-10k as the stabilizing material at a weight ratio of (2:1). Solid dispersion powder was prepared by Hot Melt method using PEG-8000 at a weight ratio of (1:2). A commercial product containing 200mg of ketoconazole tablet and pure drug powder were used as the control for comparison purposes. The dissolution studies were carried out in SGF, SIF, USP; and SIF with 0.2% sodium lauryl sulfate using the USP-II method for a 2 hours period. Physical characterizations were carried out using SEM, DSC, XRD and FTIR studies. Wet Bead Milling method yielded nanoparticles in the particles size range of (100-300nm.). First all samples were evaluated for their in-vitro dissolution in SGF at pH=1.2. After 15 minutes, the amounts of drug dissolved were observed to be 27% from both the pure powder and commercial tablet (control), 29% from solid dispersion and 100% from the Nanoparticles dosage form. This supports the fact that Nanoparticles had a strong influence on the dissolution rate of the drug and exhibited much faster dissolution of ketoconazole. When the same formulations were studied in the SIF, USP medium, the control formulation gave 3%, solid dispersion 8% and Nanoparticles 8% drug dissolution after 2 hours period. This could be because the weakly basic ketoconazole drug remained un-dissociated in the alkaline medium. Since this medium was unable to clearly distinguish the dissolution profiles from different formulation of the drug, the SIF solution

A halogen-free synthesis of gold nanoparticles using gold(III) oxide

International Nuclear Information System (INIS)

Sashuk, Volodymyr; Rogaczewski, Konrad

2016-01-01

Gold nanoparticles are one of the most used nanomaterials. They are usually synthesized by the reduction of gold(III) chloride. However, the presence of halide ions in the reaction mixture is not always welcome. In some cases, these ions have detrimental influence on the morphology and structure of resulting nanoparticles. Here, we present a simple and halogen-free procedure to prepare gold nanoparticles by reduction of gold(III) oxide in neat oleylamine. The method provides the particles with an average size below 10 nm and dispersity of tens of percent. The process of nanoparticle formation was monitored using UV–Vis spectroscopy. The structure and chemical composition of the nanoparticles was determined by SEM, XPS and EDX. We also proposed the mechanism of reduction of gold(III) oxide based on MS, IR and NMR data. Importantly, the synthetic protocol is general and applicable for the preparation of other coinage metal nanoparticles from the corresponding metal oxides. For instance, we demonstrated that the absence of halogen enables efficient alloying of metals when preparing gold–silver bimetallic nanoparticles.

Preparation of gold nanoparticles for plasmonic applications

Energy Technology Data Exchange (ETDEWEB)

Benkovicova, Monika, E-mail: monika.benkovicova@savba.sk [Institute of Physics SAS, Dubravska cesta 9, 845 11 Bratislava (Slovakia); Polymer Institute SAS, Dubravska cesta 9, 845 41 Bratislava (Slovakia); Vegso, Karol; Siffalovic, Peter; Jergel, Matej; Luby, Stefan; Majkova, Eva [Institute of Physics SAS, Dubravska cesta 9, 845 11 Bratislava (Slovakia)

2013-09-30

We present a simple hot injection method for the preparation of colloidal solutions of hydrophobic spherical gold nanoparticles with the diameter around 20 nm and size dispersion below 20%. Various surfactants with different lengths of hydrocarbon chains, such as oleylamine, 1-octadecanethiol, poly (N-vinylpyrrolidone), and AgNO{sub 3} in 1,5-pentanediol, were used for sterical stabilization in the colloidal solution. The hydrodynamic nanoparticle size and size dispersion were determined by the dynamic light scattering (DLS) while the small-angle X-ray scattering (SAXS) from the colloidal solution provided information on the size of the metallic nanoparticle core (without surfactant). Plasmon enhanced resonant absorption peaks between 500 nm and 600 nm were detected by the UV–VIS spectrophotometry. The nanoparticle arrays on silicon prepared by solvent evaporation or Langmuir-Schaefer method were inspected by high-resolution scanning electron microscopy and grazing-incidence SAXS (GISAXS). The presence of side maxima in the GISAXS pattern gives evidence of the nanoparticle ordering by self-assembly while very close values of the interparticle distance derived from GISAXS and the nanoparticle size derived from DLS indicate a close-packed order. - Highlights: ► Preparation of gold nanoparticles by use a various of surfactants ► Preparation of monodisperse nanoparticles ► Characterization of nanoparticles on a solid substrate.

Optical trapping of metal-dielectric nanoparticle clusters near photonic crystal microcavities.

Science.gov (United States)

Mejia, Camilo A; Huang, Ningfeng; Povinelli, Michelle L

2012-09-01

We predict the formation of optically trapped, metal-dielectric nanoparticle clusters above photonic crystal microcavities. We determine the conditions on particle size and position for a gold particle to be trapped above the microcavity. We then show that strong field redistribution and enhancement near the trapped gold nanoparticle results in secondary trapping sites for a pair of dielectric nanoparticles.

Transition from out-of-plane to in-plane contribution for the optical second harmonic generation response from a silver metallic nanoparticle film

Energy Technology Data Exchange (ETDEWEB)

El Harfouch, Yara; Benichou, Emmanuel; Pu, Lin; Bachelier, Guillaume; Russier-Antoine, Isabelle; Jonin, Christian; Brevet, Pierre-Francois, E-mail: Emmanuel.Benichou@lasim.univ-lyon1.fr [Laboratoire de Spectrometrie Ionique et Moleculaire, Universite Claude Bernard Lyon 1-CNRS (UMR 5579), Batiment Alfred Kastler, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France)

2011-06-29

The time evolution of the second harmonic generation (SHG) intensity during the formation of a silver spherical nanoparticle film at the water/1,2-dichloroethane interface is reported. The 5 nm diameter silver nanoparticles were initially dispersed in the water phase and their precipitation at the interface was triggered with the addition of sodium chloride. The time evolution of the SHG intensity exhibited two distinct regimes. First, an intensity increase was observed during the film formation with the deposition and the reorganization of the nanoparticles at the interface. Then, a slow decrease of the intensity due to rearrangements within the film was observed. Polarization-resolved experiments were also performed and showed that the initial dominant out-of-plane contribution of the quadratic nonlinearity underwent a reorientational change towards a dominant in-plane contribution associated with a smoother but still discontinuous metallic film.

The preparation, physicochemical properties, and the cohesive energy of liquid sodium containing titanium nanoparticles

International Nuclear Information System (INIS)

Saito, Jun-ichi; Itami, Toshio; Ara, Kuniaki

2012-01-01

Liquid sodium containing titanium nanoparticles (LSnanop) of 10-nm diameter was prepared by dispersing titanium nanoparticles (2 at.% Ti) into liquid sodium with the addition of stirring and ultrasonic sound wave. The titanium nanoparticles themselves were prepared by the vapor deposition method. This new liquid metal, LSnanop, shows a remarkable stability due to the Brownian motion of nanoparticles in liquid sodium medium. In addition, the difference of measured heat of reaction to water between this LSnanop and liquid sodium indicates the existence of cohesive energy between the liquid sodium medium and dispersed titanium nanoparticles. The origin of the cohesive energy, which serves to stabilize this new liquid metal, was explained by the model of screened nanoparticles in liquid sodium. In this model, negatively charged nanoparticles with transferred electrons from liquid sodium are surrounded by the positively charged screening shell, which may inhibit the gathering of nanoparticles by the “Coulombic repulsion coating.” The atomic volume of LSnanop shows the shrinkage from the linear law, which also suggests the existence of cohesive energy. The viscosity of LSnanop is almost the same as that of liquid sodium. This behavior was explained by the Einstein equation. The surface tension of LSnanop is 17 % larger than that of liquid sodium. The cohesive energy and the negative adsorption may be responsible to this increase. Titanium nanoparticles in liquid sodium seem to be free from the Coulomb fission. This new liquid metal containing nanoparticles suggests the possibility to prepare various stable suspensions with new properties.

Metal Nanoparticles Covered with a Metal-Organic Framework: From One-Pot Synthetic Methods to Synergistic Energy Storage and Conversion Functions.

Science.gov (United States)

Kobayashi, Hirokazu; Mitsuka, Yuko; Kitagawa, Hiroshi

2016-08-01

Hybrid materials composed of metal nanoparticles and metal-organic frameworks (MOFs) have attracted much attention in many applications, such as enhanced gas storage and catalytic, magnetic, and optical properties, because of the synergetic effects between the metal nanoparticles and MOFs. In this Forum Article, we describe our recent progress on novel synthetic methods to produce metal nanoparticles covered with a MOF (metal@MOF). We first present Pd@copper(II) 1,3,5-benzenetricarboxylate (HKUST-1) as a novel hydrogen-storage material. The HKUST-1 coating on Pd nanocrystals results in a remarkably enhanced hydrogen-storage capacity and speed in the Pd nanocrystals, originating from charge transfer from Pd nanocrystals to HKUST-1. Another material, Pd-Au@Zn(MeIM)2 (ZIF-8, where HMeIM = 2-methylimidazole), exhibits much different catalytic activity for alcohol oxidation compared with Pd-Au nanoparticles, indicating a design guideline for the development of composite catalysts with high selectivity. A composite material composed of Cu nanoparticles and Cr3F(H2O)2O{C6H3(CO2)3}2 (MIL-100-Cr) demonstrates higher catalytic activity for CO2 reduction into methanol than Cu/γ-Al2O3. We also present novel one-pot synthetic methods to produce composite materials including Pd/ZIF-8 and Ni@Ni2(dhtp) (MOF-74, where H4dhtp = 2,5-dihydroxyterephthalic acid).

Preparation and Biocompatible Surface Modification of Redox Altered Cerium Oxide Nanoparticle Promising for Nanobiology and Medicine

KAUST Repository

Nanda, Himansu Sekhar

2016-11-03

The biocompatible surface modification of metal oxide nanoparticles via surface functionalization technique has been used as an important tool in nanotechnology and medicine. In this report, we have prepared aqueous dispersible, trivalent metal ion (samarium)-doped cerium oxide nanoparticles (SmCNPs) as model redox altered CNPs of biological relevance. SmCNP surface modified with hydrophilic biocompatible (6-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-hexyl) triethoxysilane (MEEETES) were prepared using ammonia-induced ethylene glycol-assisted precipitation method and were characterized using a variety of complementary characterization techniques. The chemical interaction of functional moieties with the surface of doped nanoparticle was studied using powerful 13C cross polarization magic angle sample spinning nuclear magnetic resonance spectroscopy. The results demonstrated the production of the extremely small size MEEETES surface modified doped nanoparticles with significant reduction in aggregation compared to their unmodified state. Moreover, the functional moieties had strong chemical interaction with the surface of the doped nanoparticles. The biocompatible surface modification using MEEETES should also be extended to several other transition metal ion doped and co-doped CNPs for the production of aqueous dispersible redox altered CNPs that are promising for nanobiology and medicine.

Preparation and Biocompatible Surface Modification of Redox Altered Cerium Oxide Nanoparticle Promising for Nanobiology and Medicine

KAUST Repository

Nanda, Himansu Sekhar

2016-01-01

The biocompatible surface modification of metal oxide nanoparticles via surface functionalization technique has been used as an important tool in nanotechnology and medicine. In this report, we have prepared aqueous dispersible, trivalent metal ion (samarium)-doped cerium oxide nanoparticles (SmCNPs) as model redox altered CNPs of biological relevance. SmCNP surface modified with hydrophilic biocompatible (6-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-hexyl) triethoxysilane (MEEETES) were prepared using ammonia-induced ethylene glycol-assisted precipitation method and were characterized using a variety of complementary characterization techniques. The chemical interaction of functional moieties with the surface of doped nanoparticle was studied using powerful 13C cross polarization magic angle sample spinning nuclear magnetic resonance spectroscopy. The results demonstrated the production of the extremely small size MEEETES surface modified doped nanoparticles with significant reduction in aggregation compared to their unmodified state. Moreover, the functional moieties had strong chemical interaction with the surface of the doped nanoparticles. The biocompatible surface modification using MEEETES should also be extended to several other transition metal ion doped and co-doped CNPs for the production of aqueous dispersible redox altered CNPs that are promising for nanobiology and medicine.

Preparation and Biocompatible Surface Modification of Redox Altered Cerium Oxide Nanoparticle Promising for Nanobiology and Medicine

Directory of Open Access Journals (Sweden)

Himansu Sekhar Nanda

2016-11-01

Full Text Available The biocompatible surface modification of metal oxide nanoparticles via surface functionalization technique has been used as an important tool in nanotechnology and medicine. In this report, we have prepared aqueous dispersible, trivalent metal ion (samarium-doped cerium oxide nanoparticles (SmCNPs as model redox altered CNPs of biological relevance. SmCNP surface modified with hydrophilic biocompatible (6-{2-[2-(2-methoxy-ethoxy-ethoxy]-ethoxy}-hexyl triethoxysilane (MEEETES were prepared using ammonia-induced ethylene glycol-assisted precipitation method and were characterized using a variety of complementary characterization techniques. The chemical interaction of functional moieties with the surface of doped nanoparticle was studied using powerful 13C cross polarization magic angle sample spinning nuclear magnetic resonance spectroscopy. The results demonstrated the production of the extremely small size MEEETES surface modified doped nanoparticles with significant reduction in aggregation compared to their unmodified state. Moreover, the functional moieties had strong chemical interaction with the surface of the doped nanoparticles. The biocompatible surface modification using MEEETES should also be extended to several other transition metal ion doped and co-doped CNPs for the production of aqueous dispersible redox altered CNPs that are promising for nanobiology and medicine.

Antimicrobial polyethyleneimine-silver nanoparticles in a stable colloidal dispersion.

Science.gov (United States)

Lee, Hyun Ju; Lee, Se Guen; Oh, Eun Jung; Chung, Ho Yun; Han, Sang Ik; Kim, Eun Jung; Seo, Song Yi; Ghim, Han Do; Yeum, Jeong Hyun; Choi, Jin Hyun

2011-11-01

Excellent colloidal stability and antimicrobial activity are important parameters for silver nanoparticles (AgNPs) in a range of biomedical applications. In this study, polyethyleneimine (PEI)-capped silver nanoparticles (PEI-AgNPs) were synthesized in the presence of sodium borohydride (NaBH(4)) and PEI at room temperature. The PEI-AgNPs had a positive zeta potential of approximately +49 mV, and formed a stable nanocolloid against agglomeration due to electrostatic repulsion. The particle size and hydrodynamic cluster size showed significant correlations with the amount of PEI and NaBH(4). PEI-AgNPs and even PEI showed excellent antimicrobial activity against Staphylococus aureus and Klebsiella pneumoniae. The cytotoxic effects of PEI and PEI-AgNPs were confirmed by an evaluation of the cell viability. The results suggest that the amount of PEI should be minimized to the level that maintains the stability of PEI-AgNPs in a colloidal dispersion. Copyright © 2011 Elsevier B.V. All rights reserved.

The interfacial orientation relationship of oxide nanoparticles in a hafnium-containing oxide dispersion-strengthened austenitic stainless steel

Energy Technology Data Exchange (ETDEWEB)

Miao, Yinbin, E-mail: miao2@illinois.edu [Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Mo, Kun [Nuclear Engineering Division, Argonne National Laboratory, Lemont, IL 60493 (United States); Cui, Bai [Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Department of Material Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Chen, Wei-Ying [Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Miller, Michael K.; Powers, Kathy A. [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37830 (United States); McCreary, Virginia; Gross, David [Department of Material Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Almer, Jonathan [X-ray Science Division, Argonne National Laboratory, Lemont, IL 60493 (United States); Robertson, Ian M. [Department of Material Science and Engineering, University of Wisconsin-Madison, Madison, WA 53706 (United States); Department of Material Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Stubbins, James F. [Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)

2015-03-15

This work reports comprehensive investigations on the orientation relationship of the oxide nanoparticles in a hafnium-containing austenitic oxide dispersion-strengthened 316 stainless steel. The phases of the oxide nanoparticles were determined by a combination of scanning transmission electron microscopy–electron dispersive X-ray spectroscopy, atom probe tomography and synchrotron X-ray diffraction to be complex Y–Ti–Hf–O compounds with similar crystal structures, including bixbyite Y{sub 2}O{sub 3}, fluorite Y{sub 2}O{sub 3}–HfO{sub 2} solid solution and pyrochlore (or fluorite) Y{sub 2}(Ti,Hf){sub 2−x}O{sub 7−x}. High resolution transmission electron microscopy was used to characterize the particle–matrix interfaces. Two different coherency relationships along with one axis-parallel relation between the oxide nanoparticles and the steel matrix were found. The size of the nanoparticles significantly influences the orientation relationship. The results provide insight into the relationship of these nanoparticles with the matrix, which has implications for interpreting material properties as well as responses to radiation. - Highlights: • The oxide nanoparticles in a hafnium-containing austenitic ODS were characterized. • The nanoparticles are Y–Hf–Ti–O enriched phases according to APT and STEM–EDS. • Two coherency and an axis-parallel orientation relationships were found by HR-TEM. • Particle size has a prominent effect on the orientation relationship (OR). • Formation mechanism of the oxide nanoparticles was discussed based on the ORs.

Ionic liquid stabilized Rh Nanoparticles for Citral Cyclodehydration

NARCIS (Netherlands)

Quek, X.Y.; Guan, Y.; Santen, van R.A.; Hensen, E.J.M.

2010-01-01

Smells nice, too: The cyclodehydration of citral is achieved by using rhodium nanoparticles dispersed in an imidazolium-based ionic liquid. p-Cymene, p--dimethylstyrene, and limonene are obtained with selectivity greater than 75¿%. The interaction between the imidazolium cations and the metal

Facile route of biopolymer mediated ferrocene (FO) nanoparticles in aqueous dispersion

Energy Technology Data Exchange (ETDEWEB)

Kaus, Noor Haida Mohd., E-mail: noorhaida@usm.my [School of Chemical Sciences, Universiti Sains Malaysia, 11800, Penang, Malaysia and Centre for Organized Matter Chemistry, School of Chemistry, Cantock' s Close, BS8 1TS, Bristol (United Kingdom); Collins, A. M.; Mann, S. [Centre for Organized Matter Chemistry, School of Chemistry, Cantock' s Close, BS8 1TS, Bristol (United Kingdom)

2014-10-24

In this paper, we present a facile method for production stable aqueous dispersion of ferrocene (FO) nanoparticles. Ferrocene compounds were employed to achieve stable nanodispersions, stabilized with three different biopolymers namely, alginate, CM-dextran and chitosan. The nanoparticles produce are spherical, less than 10 nm in mean diameter and highly stable without any sedimentation. Fourier infrared transform (FTIR) and X-ray diffraction (XRD) studies confirmed the purity of ferrocene nanoparticles there is no modifications occur during the preparation route. FTIR spectra results were consistent with the presence of absorption band of cyclopentadienyl ring (C{sub 5}H{sub 5}{sup −} ion) which assigned to ν(C-C) vibrations (1409 cm-1), δ(C-H) stretching at 1001 cm{sup −1} and π(C-H) vibrations at 812 cm{sup −1}. Furthermore, all functional group for biopolymers such as CO from carboxyl group of CM-dextran and sodium alginate appears at 1712 cm{sup −1} and 1709 cm{sup −1} respectively, indicating there are steric repulsion interactions for particles stabilization. Powder X-ray diffraction patterns of sedimented samples of the biopolymers-stabilized ferrocene (FO) showed all reflections which were indexed respectively to the (−110), (001), (−201), (−111), (200), (−211), (210), (120) and (111) according to the monoclinic phase ferrocene. This confirmed that the products obtained were of high purity of Fe and EDAX analysis also suggests that the presence of the Fe element in the colloidal dispersion.

Higher-order Cn dispersion coefficients for the alkali-metal atoms

International Nuclear Information System (INIS)

Mitroy, J.; Bromley, M.W.J.

2005-01-01

The van der Waals coefficients, from C 11 through to C 16 resulting from second-, third-, and fourth-order perturbation theory are estimated for the alkali-metal (Li, Na, K, and Rb) atoms. The dispersion coefficients are also computed for all possible combinations of the alkali-metal atoms and hydrogen. The parameters are determined from sum rules after diagonalizing a semiempirical fixed core Hamiltonian in a large basis. Comparisons of the radial dependence of the C n /r n potentials give guidance as to the radial regions in which the various higher-order terms can be neglected. It is seen that including terms up to C 10 /r 10 results in a dispersion interaction that is accurate to better than 1% whenever the inter-nuclear spacing is larger than 20a 0 . This level of accuracy is mainly achieved due to the fortuitous cancellation between the repulsive (C 11 ,C 13 ,C 15 ) and attractive (C 12 ,C 14 ,C 16 ) dispersion forces

Feasibility of the development of reference materials for the detection of Ag nanoparticles in food: neat dispersions and spiked chicken meat

NARCIS (Netherlands)

Grombe, R.; Allmaier, G.; Charoud-Got, J.; Dudkiewicz, A.; Emteborg, H.; Hofmann, T.; Huusfeldt-Larsen, E.; Lehner, A.; Llinas, M.; Loeschner, K.; Molhave, K.; Peters, R.J.B.; Seghers, J.; Solans, C.; Kammer, van den F.; Wagner, S.; Weigel, S.; Linsinger, T.P.J.

2015-01-01

The feasibility of producing colloidal silver nanoparticle reference materials and silver nanoparticle spiked reference matrix materials was investigated. Two concentrations of PVP-coated silver nanoparticle dispersions were evaluated and used to spike chicken meat, with the aim of producing a set

Aluminum matrix composites reinforced with alumina nanoparticles

CERN Document Server

Casati, Riccardo

2016-01-01

This book describes the latest efforts to develop aluminum nanocomposites with enhanced damping and mechanical properties and good workability. The nanocomposites exhibited high strength, improved damping behavior and good ductility, making them suitable for use as wires. Since the production of metal matrix nanocomposites by conventional melting processes is considered extremely problematic (because of the poor wettability of the nanoparticles), different powder metallurgy routes were investigated, including high-energy ball milling and unconventional compaction methods. Special attention was paid to the structural characterization at the micro- and nanoscale, as uniform nanoparticle dispersion in metal matrix is of prime importance. The aluminum nanocomposites displayed an ultrafine microstructure reinforced with alumina nanoparticles produced in situ or added ex situ. The physical, mechanical and functional characteristics of the materials produced were evaluated using different mechanical tests and micros...

Structural analysis of platinum-palladium nanoparticles dispersed on titanium dioxide to evaluate cyclo-olefines reactivity

International Nuclear Information System (INIS)

Castillo, N.; Perez, R.; Martinez-Ortiz, M.J.; Diaz-Barriga, L.; Garcia, L.; Conde-Gallardo, A.

2010-01-01

Structural and chemical properties were correlated to explain catalytic behavior of Pt-Pd/TiO 2 in a cyclo-olefin reaction. Bimetallic nanoparticles supported on TiO 2 were prepared by wetness impregnation techniques at different concentrations of Pt and Pd ∼1 metallic wt%. The physicochemical properties of these metallic nanoparticles supported on TiO 2 were characterized by N 2 physisorption (Brunauer-Emmett-Teller-BET), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The relationship between chemical composition, physicochemical properties and particle size on the cyclo-olefin reaction was then studied. XRD and TEM results show that these nanoparticles are composed of Pt-Pd with FFC structure (a = 0.389-0.391 nm) supported on TiO 2 (anatase-like structure), and the materials present tetragonal structure nanoparticles (a = 0.37842, b = 0.37842, c = 0.95146 nm). Samples with higher contents of platinum and particle sizes of 4.2 nm show the highest catalytic conversion in cyclo-olefins reaction. Finally, structural examinations of Pt x -Pd (1-x) /TiO 2 based system was then conducted to study the effects of metals on the nanostructure of the materials.

Metal nanoparticle film–based room temperature Coulomb transistor

Science.gov (United States)

Willing, Svenja; Lehmann, Hauke; Volkmann, Mirjam; Klinke, Christian

2017-01-01

Single-electron transistors would represent an approach to developing less power–consuming microelectronic devices if room temperature operation and industry-compatible fabrication were possible. We present a concept based on stripes of small, self-assembled, colloidal, metal nanoparticles on a back-gate device architecture, which leads to well-defined and well-controllable transistor characteristics. This Coulomb transistor has three main advantages. By using the scalable Langmuir-Blodgett method, we combine high-quality chemically synthesized metal nanoparticles with standard lithography techniques. The resulting transistors show on/off ratios above 90%, reliable and sinusoidal Coulomb oscillations, and room temperature operation. Furthermore, this concept allows for versatile tuning of the device properties such as Coulomb energy gap and threshold voltage, as well as period, position, and strength of the oscillations. PMID:28740864

Metal nanoparticles triggered persistent negative photoconductivity in silk protein hydrogels

Science.gov (United States)

Gogurla, Narendar; Sinha, Arun K.; Naskar, Deboki; Kundu, Subhas C.; Ray, Samit K.

2016-03-01

Silk protein is a natural biopolymer with intriguing properties, which are attractive for next generation bio-integrated electronic and photonic devices. Here, we demonstrate the negative photoconductive response of Bombyx mori silk protein fibroin hydrogels, triggered by Au nanoparticles. The room temperature electrical conductivity of Au-silk hydrogels is found to be enhanced with the incorporation of Au nanoparticles over the control sample, due to the increased charge transporting networks within the hydrogel. Au-silk lateral photoconductor devices show a unique negative photoconductive response under an illumination of 325 nm, with excitation energy higher than the characteristic metal plasmon resonance band. The enhanced photoconductance yield in the hydrogels over the silk protein is attributed to the photo-oxidation of amino groups in the β-pleated sheets of the silk around the Au nanoparticles followed by the breaking of charge transport networks. The Au-silk nanocomposite does not show any photoresponse under visible illumination because of the localization of excited charges in Au nanoparticles. The negative photoconductive response of hybrid Au-silk under UV illumination may pave the way towards the utilization of silk for future bio-photonic devices using metal nanoparticle platforms.

Carbon composites with metal nanoparticles for Alcohol fuel cells

Science.gov (United States)

Ventrapragada, Lakshman; Siddhardha, R. S.; Podilla, Ramakrishna; Muthukumar, V. S.; Creager, Stephen; Rao, A. M.; Ramamurthy, Sai Sathish

2015-03-01

Graphene due to its high surface area and superior conductivity has attracted wide attention from both industrial and scientific communities. We chose graphene as a substrate for metal nanoparticle deposition for fuel cell applications. There are many chemical routes for fabrication of metal-graphene composites, but they have an inherent disadvantage of low performance due to the usage of surfactants, that adsorb on their surface. Here we present a design for one pot synthesis of gold nanoparticles and simultaneous deposition on graphene with laser ablation of gold strip and functionalized graphene. In this process there are two natural advantages, the nanoparticles are synthesized without any surfactants, therefore they are pristine and subsequent impregnation on graphene is linker free. These materials are well characterized with electron microscopy to find their morphology and spectroscopic techniques like Raman, UV-Vis. for functionality. This gold nanoparticle decorated graphene composite has been tested for its electrocatalytic oxidation of alcohols for alkaline fuel cell applications. An electrode made of this composite showed good stability for more than 200 cycles of operation and reported a low onset potential of 100 mV more negative, an important factor for direct ethanol fuel cells.

DNA hydrogel as a template for synthesis of ultrasmall gold nanoparticles for catalytic applications.

Science.gov (United States)

Zinchenko, Anatoly; Miwa, Yasuyuki; Lopatina, Larisa I; Sergeyev, Vladimir G; Murata, Shizuaki

2014-03-12

DNA cross-linked hydrogel was used as a matrix for synthesis of gold nanoparticles. DNA possesses a strong affinity to transition metals such as gold, which allows for the concentration of Au precursor inside a hydrogel. Further reduction of HAuCl4 inside DNA hydrogel yields well dispersed, non-aggregated spherical Au nanoparticles of 2-3 nm size. The average size of these Au nanoparticles synthesized in DNA hydrogel is the smallest reported so far for in-gel metal nanoparticles synthesis. DNA hybrid hydrogel containing gold nanoparticles showed high catalytic activity in the hydrogenation reaction of nitrophenol to aminophenol. The proposed soft hybrid material is promising as environmentally friendly and sustainable material for catalytic applications.

Impact of ultrasonic assisted triangular lattice like arranged dispersion of nanoparticles on physical and mechanical properties of epoxy-TiO2 nanocomposites.

Science.gov (United States)

Goyat, M S; Ghosh, P K

2018-04-01

Emerging ex-situ technique, ultrasonic dual mixing (UDM) offers unique and hitherto unapproachable opportunities to alter the physical and mechanical properties of polymer nanocomposites. In this study, triangular lattice-like arranged dispersion of TiO 2 nanoparticles (average size ∼ 48 nm) in the epoxy polymer has been attained via concurrent use of a probe ultra-sonicator and 4 blades pitched impeller which collectively named as UDM technique. The UDM processing of neat epoxy reveals the generation of triangular lattice-like arranged nanocavities with nanoscale inter-cavity spacing. The UDM processing of epoxy-TiO 2 nanocomposites reveals two unique features such as partial and complete entrapping of the nanoparticles by the nanocavities leading the arranged dispersion of particles in the epoxy matrix. Pristine TiO 2 nanoparticles were dispersed in the epoxy polymer at loading fractions of up to 20% by weight. The results display that the arranged dispersion of nanoparticles is very effective at enhancing the glass transition temperature (T g ) and tensile properties of the epoxy at loading fractions of 10 wt%. We quantify a direct relationship among three important parameters such as nanoparticle content, cluster size, and inter-particle spacing. Our results offer a novel understanding of these parameters on the T g and tensile properties of the epoxy nanocomposites. The tensile fracture surfaces revealed several toughening mechanisms such as particle pull-out, plastic void growth, crack deflection, crack bridging and plastic deformation. We show that a strong nanoparticle-matrix interface led to the enhanced mechanical properties due to leading toughening mechanisms such as crack deflection, plastic deformation and particle pull-out. We showed that the UDM has an inordinate prospective to alter the dispersion state of nanoparticles in viscous polymer matrices. Copyright © 2017 Elsevier B.V. All rights reserved.

Noble Metal Nanoparticles Applications in Cancer

Directory of Open Access Journals (Sweden)

João Conde

2012-01-01

Full Text Available Nanotechnology has prompted new and improved materials for biomedical applications with particular emphasis in therapy and diagnostics. Special interest has been directed at providing enhanced molecular therapeutics for cancer, where conventional approaches do not effectively differentiate between cancerous and normal cells; that is, they lack specificity. This normally causes systemic toxicity and severe and adverse side effects with concomitant loss of quality of life. Because of their small size, nanoparticles can readily interact with biomolecules both at surface and inside cells, yielding better signals and target specificity for diagnostics and therapeutics. This way, a variety of nanoparticles with the possibility of diversified modification with biomolecules have been investigated for biomedical applications including their use in highly sensitive imaging assays, thermal ablation, and radiotherapy enhancement as well as drug and gene delivery and silencing. Here, we review the available noble metal nanoparticles for cancer therapy, with particular focus on those already being translated into clinical settings.

Optical Properties and Immunoassay Applications of Noble Metal Nanoparticles

International Nuclear Information System (INIS)

Zhu, S.; Zhou, W.

2010-01-01

Noble metal, especially gold (Au) and silver (Ag) nanoparticles exhibit unique and tunable optical properties on account of their surface plasmon resonance (SPR). In this paper, we mainly discussed the theory background of the enhanced optical properties of noble metal nanoparticles. Mie theory, transfer matrix method, discrete dipole approximation (DDA) method, and finite-difference time domain (FDTD) method applied brute-force computational methods for different nanoparticles optical properties. Some important nanostructure fabrication technologies such as nanosphere lithography (NSL) and focused ion beam (FIB) are also introduced in this paper. Moreover, these fabricated nanostructures are used in the plasmonic sensing fields. The binding signal between the antibody and antigen, amyloid-derived diffusible ligands (ADDLs)-potential Alzheimer's disease (AD) biomarkers, and staphylococcal enterotoxin B (SEB) in nano-Moore per liter (nM) concentration level are detected by our designed nanobiosensor. They have many potential applications in the biosensor, environment protection, food security, and medicine safety for health, and so forth, fields.

Optical Properties and Immunoassay Applications of Noble Metal Nanoparticles

Directory of Open Access Journals (Sweden)

Shaoli Zhu

2010-01-01

Full Text Available Noble metal, especially gold (Au and silver (Ag nanoparticles exhibit unique and tunable optical properties on account of their surface plasmon resonance (SPR. In this paper, we mainly discussed the theory background of the enhanced optical properties of noble metal nanoparticles. Mie theory, transfer matrix method, discrete dipole approximation (DDA method, and finite-difference time domain (FDTD method applied brute-force computational methods for different nanoparticles optical properties. Some important nanostructure fabrication technologies such as nanosphere lithography (NSL and focused ion beam (FIB are also introduced in this paper. Moreover, these fabricated nanostructures are used in the plasmonic sensing fields. The binding signal between the antibody and antigen, amyloid-derived diffusible ligands (ADDLs-potential Alzheimer's disease (AD biomarkers, and staphylococcal enterotixn B (SEB in nano-Moore per liter (nM concentration level are detected by our designed nanobiosensor. They have many potential applications in the biosensor, environment protection, food security, and medicine safety for health, and so forth, fields.

Direct synthesis of silver nanoparticles in ionic liquid

International Nuclear Information System (INIS)

Corrêa, Cíntia M.; Bizeto, Marcos A.; Camilo, Fernanda F.

2016-01-01

Ionic liquids have structural organization at nanoscale that can trigger the spontaneous ordering of structures in nanoscopic range. Due to this characteristic, several metal nanoparticles have been prepared in this media. In this paper, we describe the direct preparation of silver nanoparticles in the following imidazolium ionic liquids: 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1,2-dimethyl-3-butylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and in citrate tetrabutylammonium, that is an ionic liquid that acts as solvent and reducing agent at the same time. We also evaluated the morphology of the nanoparticles and the stability of the dispersions. Spherical silver nanoparticles with surface Plasmon bands in the range of 400–430 nm were produced in all the ionic liquids, with the only exception for the 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide that produced a black precipitate. The best results were obtained by using 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and citrate tetrabutylammonium ionic liquids. The former resulted in concentrated spherical silver nanoparticles dispersion (ca. 1.0 mM of Ag) with diameters ranging from 6 to 12 nm and by adding polyvinylpyrrolidone (PVP) to the dispersions they became stable for at least 1 month. The citrate tetrabutylammonium ionic liquid produced even more concentrated dispersion of spherical silver nanoparticles with diameters ranging from 2 to 6 nm. These dispersions were quite stable without the need of PVP, since the Plasmon band in the electronic absorption spectra remained unaltered for months after the preparation. The citrate tetrabutylammonium ionic liquid offers a slow kinetic for the silver nanoparticle formation as the citrate is a milder reducing agent than borohydride.Graphical Abstract

Direct synthesis of silver nanoparticles in ionic liquid

Energy Technology Data Exchange (ETDEWEB)

Corrêa, Cíntia M.; Bizeto, Marcos A.; Camilo, Fernanda F., E-mail: ffcamilo@unifesp.br [Universidade Federal de São Paulo, Laboratório de Materiais Híbridos, Departamento de Ciências Exatas e da Terra, Instituto de Ciências Ambientais, Químicas e Farmacêuticas (Brazil)

2016-05-15

Ionic liquids have structural organization at nanoscale that can trigger the spontaneous ordering of structures in nanoscopic range. Due to this characteristic, several metal nanoparticles have been prepared in this media. In this paper, we describe the direct preparation of silver nanoparticles in the following imidazolium ionic liquids: 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1,2-dimethyl-3-butylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and in citrate tetrabutylammonium, that is an ionic liquid that acts as solvent and reducing agent at the same time. We also evaluated the morphology of the nanoparticles and the stability of the dispersions. Spherical silver nanoparticles with surface Plasmon bands in the range of 400–430 nm were produced in all the ionic liquids, with the only exception for the 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide that produced a black precipitate. The best results were obtained by using 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and citrate tetrabutylammonium ionic liquids. The former resulted in concentrated spherical silver nanoparticles dispersion (ca. 1.0 mM of Ag) with diameters ranging from 6 to 12 nm and by adding polyvinylpyrrolidone (PVP) to the dispersions they became stable for at least 1 month. The citrate tetrabutylammonium ionic liquid produced even more concentrated dispersion of spherical silver nanoparticles with diameters ranging from 2 to 6 nm. These dispersions were quite stable without the need of PVP, since the Plasmon band in the electronic absorption spectra remained unaltered for months after the preparation. The citrate tetrabutylammonium ionic liquid offers a slow kinetic for the silver nanoparticle formation as the citrate is a milder reducing agent than borohydride.Graphical Abstract.

High-resolution electron-beam patternable nanocomposite containing metal nanoparticles for plasmonics

International Nuclear Information System (INIS)

Abargues, R; Marques-Hueso, J; Canet-Ferrer, J; Pedrueza, E; Valdes, J L; Jimenez, E; MartInez-Pastor, J P

2008-01-01

Polymer nanocomposites containing noble metal nanoparticles are promising materials for plasmonic applications. In this paper, we report on a high-resolution negative-tone nanocomposite resist based on poly(vinyl alcohol) where silver nanoparticles and nanopatterns are simultaneously generated by electron-beam lithography. Our results indicate nanostructures with a relatively high concentration of nanoparticles and, consequently, an electromagnetic coupling among the nanoparticles. Therefore, the patternable nanocomposite described in this work may be a suitable material for future plasmonic circuitry

Gas-phase synthesis of magnetic metal/polymer nanocomposites

Science.gov (United States)

Starsich, Fabian H. L.; Hirt, Ann M.; Stark, Wendelin J.; Grass, Robert N.

2014-12-01

Highly magnetic metal Co nanoparticles were produced via reducing flame spray pyrolysis, and directly coated with an epoxy polymer in flight. The polymer content in the samples varied between 14 and 56 wt% of nominal content. A homogenous dispersion of Co nanoparticles in the resulting nanocomposites was visualized by electron microscopy. The size and crystallinity of the metallic fillers was not affected by the polymer, as shown by XRD and magnetic hysteresis measurements. The good control of the polymer content in the product nanocomposite was shown by elemental analysis. Further, the successful polymerization in the gas phase was demonstrated by electron microscopy and size measurements. The presented effective, dry and scalable one-step synthesis method for highly magnetic metal nanoparticle/polymer composites presented here may drastically decrease production costs and increase industrial yields.

Dose-dependent pulmonary response of well-dispersed titanium dioxide nanoparticles following intratracheal instillation