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Sample records for iron core nanoparticle

  1. Application of novel iron core/iron oxide shell nanoparticles to sentinel lymph node identification

    NASA Astrophysics Data System (ADS)

    Cousins, Aidan; Howard, Douglas; Henning, Anna M.; Nelson, Melanie R. M.; Tilley, Richard D.; Thierry, Benjamin

    2015-12-01

    Current `gold standard' staging of breast cancer and melanoma relies on accurate in vivo identification of the sentinel lymph node. By replacing conventional tracers (dyes and radiocolloids) with magnetic nanoparticles and using a handheld magnetometer probe for in vivo identification, it is believed the accuracy of sentinel node identification in nonsuperficial cancers can be improved due to increased spatial resolution of magnetometer probes and additional anatomical information afforded by MRI road-mapping. By using novel iron core/iron oxide shell nanoparticles, the sensitivity of sentinel node mapping via MRI can be increased due to an increased magnetic saturation compared to traditional iron oxide nanoparticles. A series of in vitro magnetic phantoms (iron core vs. iron oxide nanoparticles) were prepared to simulate magnetic particle accumulation in the sentinel lymph node. A novel handheld magnetometer probe was used to measure the relative signals of each phantom, and determine if clinical application of iron core particles can improve in vivo detection of the sentinel node compared to traditional iron oxide nanoparticles. The findings indicate that novel iron core nanoparticles above a certain size possess high magnetic saturation, but can also be produced with low coercivity and high susceptibility. While some modification to the design of handheld magnetometer probes may be required for particles with large coercivity, use of iron core particles could improve MRI and magnetometer probe detection sensitivity by up to 330 %.

  2. Surface Engineering of Core/Shell Iron/Iron Oxide Nanoparticles from Microemulsions for Hyperthermia

    PubMed Central

    Zhang, Guandong; Liao, Yifeng; Baker, Ian

    2011-01-01

    This paper describes the synthesis and surface engineering of core/shell-type iron/iron oxide nanoparticles for magnetic hyperthermia cancer therapy. Iron/iron oxide nanoparticles were synthesized from microemulsions of NaBH4 and FeCl3, followed by surface modification in which a thin hydrophobic hexamethyldisilazane layer - used to protect the iron core - replaced the CTAB coating on the particles. Phosphatidylcholine was then assembled on the nanoparticle surface. The resulting nanocomposite particles have a biocompatible surface and show good stability in both air and aqueous solution. Compared to iron oxide nanoparticles, the nanocomposites show much better heating in an alternating magnetic field. They are good candidates for both hyperthermia and magnetic resonance imaging applications. PMID:21833157

  3. High temperature oxidation of iron-iron oxide core-shell nanowires composed of iron nanoparticles.

    PubMed

    Krajewski, M; Brzozka, K; Lin, W S; Lin, H M; Tokarczyk, M; Borysiuk, J; Kowalski, G; Wasik, D

    2016-02-01

    This work describes an oxidation process of iron-iron oxide core-shell nanowires at temperatures between 100 °C and 800 °C. The studied nanomaterial was synthesized through a simple chemical reduction of iron trichloride in an external magnetic field under a constant flow of argon. The electron microscopy investigations allowed determining that the as-prepared nanowires were composed of self-assembled iron nanoparticles which were covered by a 3 nm thick oxide shell and separated from each other by a thin interface layer. Both these layers exhibited an amorphous or highly-disordered character which was traced by means of transmission electron microscopy and Mössbauer spectroscopy. The thermal oxidation was carried out under a constant flow of argon which contained the traces of oxygen. The first stage of process was related to slow transformations of amorphous Fe and amorphous iron oxides into crystalline phases and disappearance of interfaces between iron nanoparticles forming the studied nanomaterial (range: 25-300 °C). After that, the crystalline iron core and iron oxide shell became oxidized and signals for different compositions of iron oxide sheath were observed (range: 300-800 °C) using X-ray diffraction, Raman spectroscopy and Mössbauer spectroscopy. According to the thermal gravimetric analysis, the nanowires heated up to 800 °C under argon atmosphere gained 37% of mass with respect to their initial weight. The structure of the studied nanomaterial oxidized at 800 °C was mainly composed of α-Fe2O3 (∼ 93%). Moreover, iron nanowires treated above 600 °C lost their wire-like shape due to their shrinkage and collapse caused by the void coalescence. PMID:26766540

  4. Magnetic Properties of Core/Shell Structured Iron/Iron-oxide Nanoparticles Dispersed in Polymer Matrix

    NASA Astrophysics Data System (ADS)

    Nemati Porshokouh, Zohreh; Khurshid, Hafsa; Phan, Manh-Huong; Srikanth, Hariharan

    2014-03-01

    Iron-based nanoparticles (NPs) show interesting magnetic properties for a wide range of applications; however rapid oxidation of iron limits its practical use. Protecting iron with a thin layer of iron-oxide is a possible way to prevent oxidation, forming core/shell (CS) iron/iron-oxide. Due to the different diffusivity rates of the two materials, a gap appears between the core and shell after a period of time (Kirkendall effect), degrading the magnetic properties of the sample. We minimize the Kirkendall effect while retaining good magnetic properties of ~12.5 nm CS iron/iron-oxide NPs by dispersing them into a polymer matrix. Magnetic measurements reveal that after a period of 3 months the blocking temperature (TB) of as-made CS NPs decreases from 107 K to 90 K. The change in TB marks the formation of a gap between the core and shell, which is also evident from HRTEM studies. By contrast, NPs dispersed in RP show no change in TB over the same time period. We repeated experiments with ~10.5 nm CS NPs and the results are consistent. Our study shows the importance of dispersing CS NPs in polymers to preserve desirable magnetic properties for practical applications, ranging from RF sensors and microwave devices to bioengineering.

  5. Microemulsion Synthesis of Iron Core/Iron Oxide Shell Magnetic Nanoparticles and Their Physicochemical Properties

    PubMed Central

    Kekalo, Katsiaryna; Koo, Katherine; Zeitchick, Evan; Baker, Ian

    2015-01-01

    Iron magnetic nanoparticles were synthesized under an inert atmosphere via the reaction between FeCl3 and NaBH4 in droplets of water in a microemulsion consisting of octane with cetyl trimethylammonium bromide and butanol as surfactants. A thin Fe3O4 layer was produced on the iron nanoparticles using slow, controlled oxidation at room temperature. A silica shell was deposited on the Fe3O4 using 3-aminopropyltrimethoxysilane following the method of Zhang et al. [Mater. Sci. Eng. C 30 (2010) 92–97]. The structure and chemistry of the resulting nanoparticles were studied using variety of methods and their magnetic properties were determined. The diameter of the iron core was typically 8–16 nm, while the thickness of the Fe3O4 shell was 2–3 nm. The presence of the silica layer was confirmed using Fourier transform infra-red spectroscopy and the number of NH2-groups on each nanoparticle was determined based on colorimetric tests using ortho-phthalaldehyde. PMID:26549922

  6. Synthesis and characterization of PEG-iron oxide core-shell composite nanoparticles for thermal therapy.

    PubMed

    Wydra, Robert J; Kruse, Anastasia M; Bae, Younsoo; Anderson, Kimberly W; Hilt, J Zach

    2013-12-01

    In this study, core-shell nanoparticles were developed to achieve thermal therapy that can ablate cancer cells in a remotely controlled manner. The core-shell nanoparticles were prepared using atomic transfer radical polymerization (ATRP) to coat iron oxide (Fe3O4) nanoparticles with a poly(ethylene glycol) (PEG) based polymer shell. The iron oxide core allows for the remote heating of the particles in an alternating magnetic field (AMF). The coating of iron oxide with PEG was verified through Fourier transform infrared spectroscopy and thermal gravimetric analysis. A thermoablation (55°C) study was performed on A549 lung carcinoma cells exposed to nanoparticles and over a 10 min AMF exposure. The successful thermoablation of A549 demonstrates the potential use of polymer coated particles for thermal therapy.

  7. Synthesis of core-shell iron nanoparticles via a new (novel) approach

    NASA Astrophysics Data System (ADS)

    Chaudhary, Rakesh P.; Koymen, Ali R.

    2014-03-01

    Carbon-encapsulated iron (Fe) nanoparticles were synthesized by a newly developed method in toluene. Transmission Electron Microscopy (TEM) and High Resolution Transmission Electron Microscopy (HRTEM) of the as prepared sample reveal that core-shell nanostructures have been formed with Fe as core and graphitic carbon as shell. Fe nanoparticles with diameter 11nm to 102 nm are encapsulated by 6-8 nm thick graphitic carbon layers. There was no iron carbide formation observed between the Fe core and the graphitic shell. The Fe nanoparticles have body centered cubic (bcc) crystal structure. The magnetic hysteresis loop of the as synthesized powder at room temperature showed a saturation magnetization of 9 Am2 kg-1. After thermal treatment crystalline order of the samples improved and hence saturation magnetization increased to 24 Am2kg-1. We foresee that the carbon-encapsulated Fe nanoparticles are biologically friendly and could have potential applications in Magnetic Resonance Imaging (MRI) and Photothermal cancer therapy.

  8. Synthesis and Magneto-Thermal Actuation of Iron Oxide Core-PNIPAM Shell Nanoparticles.

    PubMed

    Kurzhals, Steffen; Zirbs, Ronald; Reimhult, Erik

    2015-09-01

    Superparamagnetic nanoparticles have been proposed for many applications in biotechnology and medicine. In this paper, it is demonstrated how the excellent colloidal stability and magnetic properties of monodisperse and individually densely grafted iron oxide nanoparticles can be used to manipulate reversibly the solubility of nanoparticles with a poly(N-isopropylacrylamide)nitrodopamine shell. "Grafting-to" and "grafting-from" methods for synthesis of an irreversibly anchored brush shell to monodisperse, oleic acid coated iron oxide cores are compared. Thereafter, it is shown that local heating by magnetic fields as well as global thermal heating can be used to efficiently and reversibly aggregate, magnetically extract nanoparticles from solution and spontaneously redisperse them. The coupling of magnetic and thermally responsive properties points to novel uses as smart materials, for example, in integrated devices for molecular separation and extraction.

  9. Functionalized magnetic iron oxide/alginate core-shell nanoparticles for targeting hyperthermia.

    PubMed

    Liao, Shih-Hsiang; Liu, Chia-Hung; Bastakoti, Bishnu Prasad; Suzuki, Norihiro; Chang, Yung; Yamauchi, Yusuke; Lin, Feng-Huei; Wu, Kevin C-W

    2015-01-01

    Hyperthermia is one of the promising treatments for cancer therapy. However, the development of a magnetic fluid agent that can selectively target a tumor and efficiently elevate temperature while exhibiting excellent biocompatibility still remains challenging. Here a new core-shell nanostructure consisting of inorganic iron oxide (Fe3O4) nanoparticles as the core, organic alginate as the shell, and cell-targeting ligands (ie, D-galactosamine) decorated on the outer surface (denoted as Fe3O4@Alg-GA nanoparticles) was prepared using a combination of a pre-gel method and coprecipitation in aqueous solution. After treatment with an AC magnetic field, the results indicate that Fe3O4@Alg-GA nanoparticles had excellent hyperthermic efficacy in a human hepatocellular carcinoma cell line (HepG2) owing to enhanced cellular uptake, and show great potential as therapeutic agents for future in vivo drug delivery systems. PMID:26005343

  10. Functionalized magnetic iron oxide/alginate core-shell nanoparticles for targeting hyperthermia

    PubMed Central

    Liao, Shih-Hsiang; Liu, Chia-Hung; Bastakoti, Bishnu Prasad; Suzuki, Norihiro; Chang, Yung; Yamauchi, Yusuke; Lin, Feng-Huei; Wu, Kevin C-W

    2015-01-01

    Hyperthermia is one of the promising treatments for cancer therapy. However, the development of a magnetic fluid agent that can selectively target a tumor and efficiently elevate temperature while exhibiting excellent biocompatibility still remains challenging. Here a new core-shell nanostructure consisting of inorganic iron oxide (Fe3O4) nanoparticles as the core, organic alginate as the shell, and cell-targeting ligands (ie, D-galactosamine) decorated on the outer surface (denoted as Fe3O4@Alg-GA nanoparticles) was prepared using a combination of a pre-gel method and coprecipitation in aqueous solution. After treatment with an AC magnetic field, the results indicate that Fe3O4@Alg-GA nanoparticles had excellent hyperthermic efficacy in a human hepatocellular carcinoma cell line (HepG2) owing to enhanced cellular uptake, and show great potential as therapeutic agents for future in vivo drug delivery systems. PMID:26005343

  11. Preparation and characterization of carbonyl iron/poly(butylcyanoacrylate) core/shell nanoparticles.

    PubMed

    Arias, J L; Gallardo, V; Linares-Molinero, F; Delgado, A V

    2006-07-15

    In this article a method is described to prepare composite colloidal nanoparticles, consisting of a magnetic core (carbonyl iron) and a biodegradable polymeric shell [poly(butylcyanoacrylate) or PBCA]. The method is based on the so-called anionic polymerization procedure, often used in the synthesis of poly(alkylcyanoacrylate) nanospheres designed for drug delivery. Interest of this investigation is based upon the fact that the heterogeneous structure of the particles can confer them both the possibility to respond to external magnetic fields and to be used as drug carriers. In order to investigate to what extent do the particles participate of this mixed properties, we compare in this work the physical characteristics (structure, chemical composition, specific surface area and surface electrical and thermodynamic properties) of the core/shell particles with those of both the nucleus and the coating material. This preliminary study shows that the mixed particles display an intermediate behavior between that of carbonyl iron and PBCA spheres. Electrophoretic mobility measurements as a function of pH and as a function of KNO3 concentration, show a great similarity between the core/shell and pure polymer nanoparticles. Similarly, a surface thermodynamic study performed on the three types of particles demonstrated that the electron-donor component of the surface free energy of the solids is very sensitive to the surface composition. In fact, a measurable decrease of such component is found for core/shell particles as compared to carbonyl iron. We also analyzed the influence of the relative amounts of polymer and carbonyl iron on the characteristics of the composite particles: data on the coating thickness, the amount of polymer bound to the magnetic nuclei, the redispersibility characteristics of the suspensions and the surface electrical and thermodynamic properties, suggest that the optimal synthesis conditions are obtained for a 4/3 initial monomer/carbonyl iron

  12. Iron Oxide-Gold Core-Shell Nanoparticles and Thin-Film Assembly

    SciTech Connect

    Wang, Lingyan; Luo, Jin; Maye, Mathew M.; Fan, Quan; Qiang, Rendeng; Engelhard, Mark H.; Wang, Chong M.; Lin, Yuehe; Zhong, Chuan-Jian

    2005-05-04

    This paper reports findings of an investigation of the synthesis of monolayer-capped iron oxide and core (iron oxide)–shell (gold) nanocomposite and their assembly towards thin film materials. Pre-synthesized and size-defined iron oxide nanoparticles were used as seeding materials for the reduction of gold precursors, which was shown to be effective for coating the iron oxide cores with gold shells (Fe oxide@Au). The unique aspect of our synthesis is the formation of Fe oxide@Au core–shell nanoparticles with controllable surface properties. The novelty of our assembly strategy is the exploitation of the ligand-exchange reactivity at the gold shells for the thin film assembly of the core–shell nanoparticles. The core–shell nanocomposites and assemblies have been characterized using TEM, XRD, XPS, FTIR, TGA, and DCP-AES techniques. In addition to evidence from TEM detection of the change in particle size, UV-Vis observation of the change in the surface plasmon resonance band, and XRD detection of disappearance of the magnetite diffraction peaks after coating the gold shell, the formation of the core–shell morphology was further confirmed by DCP-AES composition analysis of Au and Fe in the molecularly-mediated thin film assembly of Fe oxide@Au particles. The interparticle ligand exchange–precipitation chemistry at the gold shell is to our knowledge the first example demonstrating the inter-shell reactivity for constructing thin films of Fe oxide@Au particles. The results have provided important insights into the design of interfacial reactivities via core–shell nanocomposites for magnetic, catalytic and biosensing applications.

  13. High performance multi-core iron oxide nanoparticles for magnetic hyperthermia: microwave synthesis, and the role of core-to-core interactions.

    PubMed

    Blanco-Andujar, C; Ortega, D; Southern, P; Pankhurst, Q A; Thanh, N T K

    2015-02-01

    The adoption of magnetic hyperthermia as either a stand-alone or adjunct therapy for cancer is still far from being optimised due to the variable performance found in many iron oxide nanoparticle systems, including commercially available formulations. Herein, we present a reproducible and potentially scalable microwave-based method to make stable citric acid coated multi-core iron oxide nanoparticles, with exceptional magnetic heating parameters, viz. intrinsic loss parameters (ILPs) of up to 4.1 nH m(2) kg(-1), 35% better than the best commercial equivalents. We also probe the core-to-core magnetic interactions in the particles via remanence-derived Henkel and ΔM plots. These reveal a monotonic dependence of the ILP on the magnetic interaction field Hint, and show that the interactions are demagnetising in nature, and act to hinder the magnetic heating mechanism.

  14. Core-shell composite particles composed of biodegradable polymer particles and magnetic iron oxide nanoparticles for targeted drug delivery

    NASA Astrophysics Data System (ADS)

    Oka, Chiemi; Ushimaru, Kazunori; Horiishi, Nanao; Tsuge, Takeharu; Kitamoto, Yoshitaka

    2015-05-01

    Core-shell composite particles with biodegradability and superparamagnetic behavior were prepared using a Pickering emulsion for targeted drug delivery based on magnetic guidance. The composite particles were composed of a core of biodegradable polymer and a shell of assembled magnetic iron oxide nanoparticles. It was found that the dispersibility of the nanoparticles is crucial for controlling the core-shell structure. The addition of a small amount of dispersant into the nanoparticle's suspension could improve the dispersibility and led to the formation of composite particles with a thin magnetic shell covering a polymeric core. The composite particles were also fabricated with a model drug loaded into the core, which was released via hydrolysis of the core under strong alkaline conditions. Because the core can also be biodegraded by lipase, this result suggests that the slow release of the drug from the composite particles should occur inside the body.

  15. Size-dependent structural evolution of the biomineralized iron-core nanoparticles in ferritins

    NASA Astrophysics Data System (ADS)

    Lee, Eunsook; Kim, D. H.; Hwang, Jihoon; Lee, Kiho; Yoon, Sungwon; Suh, B. J.; Hyun Kim, Kyung; Kim, J.-Y.; Jang, Z. H.; Kim, Bongjae; Min, B. I.; Kang, J.-S.

    2013-04-01

    The structural identity of the biomineralized iron core nanoparticles in Helicobacter pylori ferritins (Hpf's) has been determined by employing soft x-ray absorption spectroscopy and soft x-ray magnetic circular dichroism. Valence states of Fe ions are nearly trivalent in all Hpf's, indicating that the amount of magnetite (Fe3O4) is negligible. With increasing filling of Fe ions, the local configurations of Fe3+ ions change from the mixture of the tetrahedral and octahedral symmetries to the octahedral symmetry. These results demonstrate that the biomineralization of the ferritin core changes from maghemite-like (γ-Fe2O3) formation to hematite-like (α-Fe2O3) formation with increasing Fe content.

  16. Substitution of manganese and iron into hydroxyapatite: Core/shell nanoparticles

    SciTech Connect

    Pon-On, Weeraphat; Meejoo, Siwaporn; Tang, I.-Ming

    2008-08-04

    The bioceramics, hydroxyapatite (HAP), is a material which is biocompatible to the human body and is well suited to be used in hyperthermia applications for the treatment of bone cancer. We investigate the substitution of iron and manganese into the hydroxyapatite to yield ceramics having the empirical formula Ca{sub 9.4}Fe{sub 0.4}Mn{sub 0.2}(PO{sub 4}){sub 6}(OH){sub 2}. The samples were prepared by the co-precipitation method. The formation of the nanocrystallites in the HAP structure as the heating temperatures were raised to obtain a glass-ceramic system are confirmed by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED) and electron spin resonance (ESR). TEM images show the core/shell structure of the nanoparticles, with the core being formed by the ferrites and the shell by the hydroxyapatite. The ED patterns indicate the nanoparticles formed at 500 deg. C have an amorphous structure while the nanoparticles formed at 1000 deg. C are crystalline. ESR spectroscopy indicated that the Fe{sup 3+} ions have a g-factor of 4.23 and the Mn{sup 2+} ions have a g-factor of 2.01. The values of the parameters in the spin Hamiltonian which describes the interaction between the transition metal ions and the Ca{sup 2+} ions, indicate that the Mn{sup 2+} ion substitute into the Ca{sup 2+} sites which are ninefold coordinated, i.e., the Ca(1) sites.

  17. Engineering of Superparamagnetic Core-Shell Iron Oxide/N-Chloramine Nanoparticles for Water Purification.

    PubMed

    Haham, Hai; Natan, Michal; Gutman, Ori; Kolitz-Domb, Michal; Banin, Ehud; Margel, Shlomo

    2016-07-20

    In this study, we describe the synthesis and characterization of superparamagnetic core-shell iron oxide (IO)/N-halamine antibacterial nanoparticles (NPs). For this purpose, superparamagnetic IO core NPs were coated with cross-linked polymethacrylamide (PMAA) by surfactant-free dispersion copolymerization of methacrylamide and N,N-methylenebis(acrylamide) in an aqueous continuous phase. The effect of the polymerization process on the chemical composition, size, shape, crystallinity, and magnetic properties of the IO/PMAA NPs was elucidated. Conversion of the core-shell IO/PMAA NPs into their N-halamine form, IO/PMAA-Cl, was accomplished using a chlorination reaction with sodium hypochlorite. The influence of chlorination on the shape, crystallinity, and magnetic properties of the IO/PMAA NPs was studied. The IO/PMAA-Cl NPs demonstrated excellent antibacterial activity against Gram-negative and Gram-positive bacteria. Finally, the chlorination recharging capabilities of the NPs and their potential for use in the purification of water containing bacteria were demonstrated with magnetic columns packed with the IO/PMAA-Cl NPs. PMID:27348740

  18. Stabilization of superparamagnetic iron oxide core-gold shell nanoparticles in high ionic strength media.

    PubMed

    Lim, Jit Kang; Majetich, Sara A; Tilton, Robert D

    2009-12-01

    Nanoparticles with monodisperse, spherical magnetic iron oxide cores and contiguous gold shells (Fe/Au NPs) have been synthesized in order to combine magnetophoretic responsiveness and localized surface plasmon resonance in a single nanoparticle. Such particles are sufficiently charged to be stable against flocculation in low ionic strength media, but they require surface modification to be stably dispersed in elevated ionic strength media that are appropriate for biotechnological applications. Dynamic light scattering and ultraviolet-visible spectrophotometry are used to monitor the colloidal stability of Fe/Au NPs in pH 7.4 phosphate buffered saline containing 154 mM NaCl (PBS). While uncoated particles flocculate immediately upon introduction to PBS, Fe/Au NPs with adsorbed layers of bovine serum albumin or the amphiphilic triblock copolymers Pluronic F127 and Pluronic F68 resist flocculation after more than 5 days in PBS. Adsorbed dextran allowed flocculation that was limited to the formation of small clusters, while poly(ethylene glycol) homopolymers ranging in molecular weight from 6000 to 100 000 were ineffective steric stabilizers. The effectiveness of adsorbed Pluronic copolymers as steric stabilizers was interpreted in terms of the measured adsorbed layer thickness and extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory predictions of interparticle interactions.

  19. The Magnetophoretic Mobility and Superparamagnetism of Core-Shell Iron Oxide Nanoparticles with Dual Targeting and Imaging Functionality

    PubMed Central

    Yu, Faquan; Zhang, Lei; Huang, Yongzhuo; Sun, Kai; David, Allan E.; Yang, Victor C.

    2010-01-01

    With the goal to achieve highly efficacious MRI-monitored magnetic targeting, a novel drug carrier with dual nature of superior magnetophoretic mobility and superparamagnetism was synthesized. This carrier was specially designed in a core-shell structure. The core was achieved by utilizing a strategy of self-assembly of oppositely charged ultrafine superparamagnetic iron oxide nanoparticles previously prepared. The final particles were formed by coating such cores with carboxymethyldextran (CMD) polymer. By exclusion of non-magnetic materials from the interior part of the particles, this structure maximized the amount of magnetic material and thus yielded a superior magnetophoretic mobility. Such a strategy avoids the challenge of superparamagnetism loss, which would be caused by cores exceeding a critical domain size. Coating the self-assembled core enables the magnetic carrier to be stable upon usage and storage and to be readily linked with drug molecules for therapeutic applications. In vitro characterization showed that these nanoparticles displayed a 3- to 4-fold enhancement in magnetophoretic mobility, and a markedly improved stability when stored in 50% serum as a comparison of conventional iron oxide-based magnetic nanoparticles. Preliminary in vivo studies revealed that the nanoparticles alsofunction well as a contrast enhancer for MR imaging of brain glioma. This technology could lead to the development of a new paradigm of magnetic carriers that meet with the needs of various clinical applications. PMID:20434209

  20. Anti-cancer drug loaded iron-gold core-shell nanoparticles (Fe@Au) for magnetic drug targeting.

    PubMed

    Kayal, Sibnath; Ramanujan, Raju Vijayaraghavan

    2010-09-01

    Magnetic drug targeting, using core-shell magnetic carrier particles loaded with anti-cancer drugs, is an emerging and significant method of cancer treatment. Gold shell-iron core nanoparticles (Fe@Au) were synthesized by the reverse micelle method with aqueous reactants, surfactant, co-surfactant and oil phase. XRD, XPS, TEM and magnetic property measurements were utilized to characterize these core-shell nanoparticles. Magnetic measurements showed that the particles were superparamagnetic at room temperature and that the saturation magnetization decreased with increasing gold concentration. The anti-cancer drug doxorubicin (DOX) was loaded onto these Fe@Au nanoparticle carriers and the drug release profiles showed that upto 25% of adsorbed drug was released in 80 h. It was found that the amine (-NH2) group of DOX binds to the gold shell. An in vitro apparatus simulating the human circulatory system was used to determine the retention of these nanoparticle carriers when exposed to an external magnetic field. A high percentage of magnetic carriers could be retained for physiologically relevant flow speeds of fluid. The present findings show that DOX loaded gold coated iron nanoparticles are promising for magnetically targeted drug delivery. PMID:21133071

  1. Solvent-surface interactions control the phase structure in laser-generated iron-gold core-shell nanoparticles

    PubMed Central

    Wagener, Philipp; Jakobi, Jurij; Rehbock, Christoph; Chakravadhanula, Venkata Sai Kiran; Thede, Claas; Wiedwald, Ulf; Bartsch, Mathias; Kienle, Lorenz; Barcikowski, Stephan

    2016-01-01

    This work highlights a strategy for the one-step synthesis of FeAu nanoparticles by the pulsed laser ablation of alloy targets in the presence of different solvents. This method allows particle generation without the use of additional chemicals; hence, solvent-metal interactions could be studied without cross effects from organic surface ligands. A detailed analysis of generated particles via transmission electron microscopy in combination with EDX elemental mapping could conclusively verify that the nature of the used solvent governs the internal phase structure of the formed nanoparticles. In the presence of acetone or methyl methacrylate, a gold shell covering a non-oxidized iron core was formed, whereas in aqueous media, an Au core with an Fe3O4 shell was generated. This core-shell morphology was the predominant species found in >90% of the examined nanoparticles. These findings indicate that fundamental chemical interactions between the nanoparticle surface and the solvent significantly contribute to phase segregation and elemental distribution in FeAu nanoparticles. A consecutive analysis of resulting Fe@Au core-shell nanoparticles revealed outstanding oxidation resistance and fair magnetic and optical properties. In particular, the combination of these features with high stability magnetism and plasmonics may create new opportunities for this hybrid material in imaging applications. PMID:27004738

  2. Solvent-surface interactions control the phase structure in laser-generated iron-gold core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Wagener, Philipp; Jakobi, Jurij; Rehbock, Christoph; Chakravadhanula, Venkata Sai Kiran; Thede, Claas; Wiedwald, Ulf; Bartsch, Mathias; Kienle, Lorenz; Barcikowski, Stephan

    2016-03-01

    This work highlights a strategy for the one-step synthesis of FeAu nanoparticles by the pulsed laser ablation of alloy targets in the presence of different solvents. This method allows particle generation without the use of additional chemicals; hence, solvent-metal interactions could be studied without cross effects from organic surface ligands. A detailed analysis of generated particles via transmission electron microscopy in combination with EDX elemental mapping could conclusively verify that the nature of the used solvent governs the internal phase structure of the formed nanoparticles. In the presence of acetone or methyl methacrylate, a gold shell covering a non-oxidized iron core was formed, whereas in aqueous media, an Au core with an Fe3O4 shell was generated. This core-shell morphology was the predominant species found in >90% of the examined nanoparticles. These findings indicate that fundamental chemical interactions between the nanoparticle surface and the solvent significantly contribute to phase segregation and elemental distribution in FeAu nanoparticles. A consecutive analysis of resulting Fe@Au core-shell nanoparticles revealed outstanding oxidation resistance and fair magnetic and optical properties. In particular, the combination of these features with high stability magnetism and plasmonics may create new opportunities for this hybrid material in imaging applications.

  3. Enhanced bio-compatibility of ferrofluids of self-assembled superparamagnetic iron oxide-silica core-shell nanoparticles.

    PubMed

    Narayanan, T N; Mary, A P Reena; Swalih, P K Anas; Kumar, D Sakthi; Makarov, D; Albrecht, M; Puthumana, Jayesh; Anas, Abdulaziz; Anantharaman, M R

    2011-03-01

    Self-assembled magnetic colloidal suspensions are sought after by material scientists owing to its huge application potential. The biomedical applications of colloidal nanoparticles necessitate that they are biocompatible, non-interacting, monodispersed and hence the synthesis of such nanostructures has great relevance in the realm of nanoscience. Silica-coated superparamagnetic iron oxide nanoparticles based ferrofluids were prepared using polyethylene glycol as carrier fluid by employing a controlled co-precipitation technique followed by a modified sol-gel synthesis. A plausible mechanism for the formation of stable suspension of SiO2-coated Iron Oxide nanoparticles with a size of about 9 nm dispersed in polyethylene glycol (PEG) is proposed. Core-shell nature of the resultant SiO2-Iron Oxide nanocomposite was verified using transmission electron microscopy. Fourier transform-infrared spectroscopy studies were carried out to understand the structure and nature of chemical bonds. The result suggests that Iron Oxide exist in an isolated state inside silica matrix. Moreover, the presence of silanol bonds establishes the hydrophilic nature of silica shell confirming the formation of stable ferrofluid with PEG as carrier fluid. The magnetic characterization reveals the superparamagnetic behavior of the nanoparticles with a rather narrow distribution of blocking temperatures. These properties are not seen in ferrofluids prepared from Iron Oxide nanoparticles without SiO2 coating. The latter suggests the successful tuning of the inter-particle interactions preventing agglomeration of nanoparticles. Cytotoxicity studies on citric acid coated water based ferrofluid and silica-coated PEG-based ferrofluid were evaluated by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium chloride assay and it shows an enhanced compatibility for silica modified nanoparticles. PMID:21449334

  4. Enhanced bio-compatibility of ferrofluids of self-assembled superparamagnetic iron oxide-silica core-shell nanoparticles.

    PubMed

    Narayanan, T N; Mary, A P Reena; Swalih, P K Anas; Kumar, D Sakthi; Makarov, D; Albrecht, M; Puthumana, Jayesh; Anas, Abdulaziz; Anantharaman, M R

    2011-03-01

    Self-assembled magnetic colloidal suspensions are sought after by material scientists owing to its huge application potential. The biomedical applications of colloidal nanoparticles necessitate that they are biocompatible, non-interacting, monodispersed and hence the synthesis of such nanostructures has great relevance in the realm of nanoscience. Silica-coated superparamagnetic iron oxide nanoparticles based ferrofluids were prepared using polyethylene glycol as carrier fluid by employing a controlled co-precipitation technique followed by a modified sol-gel synthesis. A plausible mechanism for the formation of stable suspension of SiO2-coated Iron Oxide nanoparticles with a size of about 9 nm dispersed in polyethylene glycol (PEG) is proposed. Core-shell nature of the resultant SiO2-Iron Oxide nanocomposite was verified using transmission electron microscopy. Fourier transform-infrared spectroscopy studies were carried out to understand the structure and nature of chemical bonds. The result suggests that Iron Oxide exist in an isolated state inside silica matrix. Moreover, the presence of silanol bonds establishes the hydrophilic nature of silica shell confirming the formation of stable ferrofluid with PEG as carrier fluid. The magnetic characterization reveals the superparamagnetic behavior of the nanoparticles with a rather narrow distribution of blocking temperatures. These properties are not seen in ferrofluids prepared from Iron Oxide nanoparticles without SiO2 coating. The latter suggests the successful tuning of the inter-particle interactions preventing agglomeration of nanoparticles. Cytotoxicity studies on citric acid coated water based ferrofluid and silica-coated PEG-based ferrofluid were evaluated by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium chloride assay and it shows an enhanced compatibility for silica modified nanoparticles.

  5. Hematite Core Nanoparticles with Carbon Shell: Potential for Environmentally Friendly Production from Iron Mining Sludge

    NASA Astrophysics Data System (ADS)

    Stević, Dragana; Mihajlović, Dijana; Kukobat, Radovan; Hattori, Yoshiyuki; Sagisaka, Kento; Kaneko, Katsumi; Atlagić, Suzana Gotovac

    2016-08-01

    Hematite nanoparticles with amorphous, yet relatively uniform carbon shell, were produced based exclusively on the waste sludge from the iron mine as the raw material. The procedure for acid digestion-based purification of the sludge with the full recovery of acid vapors and the remaining non-toxic rubble is described. Synthesis of the hematite nanoparticles was performed by the arrested precipitation method with cationic surfactant. The particles were thoroughly characterized and the potential of their economical production for the battery industry is indicated.

  6. Synthesis and characterization of PVP-coated large core iron oxide nanoparticles as an MRI contrast agent

    NASA Astrophysics Data System (ADS)

    Lee, Ha-Young; Lee, Sang-Hoon; Xu, Chenjie; Xie, Jin; Lee, Jin-Hyung; Wu, Bing; Leen Koh, Ai; Wang, Xiaoying; Sinclair, Robert; Wang, Shan X.; Nishimura, Dwight G.; Biswal, Sandip; Sun, Shouheng; Cho, Sun Hang; Chen, Xiaoyuan

    2008-04-01

    The purpose of this study was to synthesize biocompatible polyvinylpyrrolidone (PVP)-coated iron oxide (PVP-IO) nanoparticles and to evaluate their efficacy as a magnetic resonance imaging (MRI) contrast agent. The PVP-IO nanoparticles were synthesized by a thermal decomposition method and characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), and a superconducting quantum interface device (SQUID). The core size of the particles is about 8 10 nm and the overall size is around 20 30 nm. The measured r2 (reciprocal of T2 relaxation time) and r2* (reciprocal of T2* relaxation time) are 141.2 and 338.1 (s mM)-1, respectively. The particles are highly soluble and stable in various buffers and in serum. The macrophage uptake of PVP-IO is comparable to that of Feridex as measured by a Prussian blue iron stain and phantom study. The signal intensity of a rabbit liver was effectively reduced after intravenous administration of PVP-IO. Therefore PVP-IO nanoparticles are potentially useful for T2-weighted MR imaging.

  7. Poly(D,L-lactide-co-glycolide) microcomposite containing magnetic iron core nanoparticles as a drug carrier

    NASA Astrophysics Data System (ADS)

    Naik, Sweta; Carpenter, Everett E.

    2008-04-01

    Today many potent anticancer drugs like cisplatin are available which carry a number of side effects. A promising way of reducing the side effects is to target the drug to tissue sites by coating it with biocompatible materials like Poly (dl-lactide-co-glycolide) (PLGA) polymer where controlled drug release is achieved during the biodegradation of the polymer. Also the efficacy of anticancer drugs like cisplatin increases at elevated temperatures, so if local heating can be achieved where the drug is targeted. Local heating can be achieved by introducing iron core nanoparticles in the composites along with the drug, which can be heated by the 2.4 GHz microwaves. Local heating of the nanocomposites also helps to swell the polymer shell and enhance the drug release. The magnetic nanocomposites were synthesized using iron nanoparticles, PLGA and a fluorescent dye, tris-(2,2'bipyridyl) dichlororuthenium (II) using an oil-in-emulsion technique. The emulsion contains PLGA, dye, and iron nanoparticles dissolved in the oil phase and polyvinyl alcohol (PVA) as a stabilizer. As the sample is homogenized, and dried, uniform 100 nm composites are formed where the dye and iron nanoparticles are encapsulated in a PLGA shell. Control of the thickness and loading efficiency of the nanocomposite can be controlled by varying the ratio of PLGA, iron, and dye. The amount of loading was determined using TGA confirming from 20-50% (w/w) loading. As the dye is released from the composite the fluorescence intensity decreases due to self-quenching. This self-quenching allows for the determination of the release kinetics as a function of temperature using fluorescence spectroscopy. Initial results suggest that there is a release of 5-10% of the dye from the composite at 25°C and complete release after the nanocomposite reaches 90°C. Using local microwave heating the complete release of the dye can be accomplished with three two second pulses of 2.4 GHz microwaves. This allows for the

  8. Synthesis and morphology of iron-iron oxide core-shell nanoparticles produced by high pressure gas condensation

    NASA Astrophysics Data System (ADS)

    Xing, Lijuan; ten Brink, Gert H.; Chen, Bin; Schmidt, Franz P.; Haberfehlner, Georg; Hofer, Ferdinand; Kooi, Bart J.; Palasantzas, George

    2016-05-01

    Core-shell structured Fe nanoparticles (NPs) produced by high pressure magnetron sputtering gas condensation were studied using transmission electron microscopy (TEM) techniques, electron diffraction, electron energy-loss spectroscopy (EELS), tomographic reconstruction, and Wulff shape construction analysis. The core-shell structure, which is composed of an Fe core surrounded by a maghemite (γ-Fe2O3) and/or magnetite (Fe3O4) shell, was confirmed by fast Fourier transform (FFT) analysis combined with EELS. It was found that the particle size and shape strongly depend on the gas environment. Moreover, extensive analysis showed that NPs with a size between 10-20 nm possess a truncated cubic morphology, which is confined by the 6 {100} planes that are truncated by the 12 {110} planes at different degrees. For NPs larger than 20 nm, the rhombic dodecahedron defined by the 12 {110} planes is the predominant crystal shape, while truncated rhombic dodecahedrons, as well as non-truncated and truncated cubic NPs, were also observed. The NPs without truncation showed a characteristic inward relaxation indicating that besides thermodynamics kinetics also plays a crucial role during particle growth.

  9. Synthesis and morphology of iron-iron oxide core-shell nanoparticles produced by high pressure gas condensation.

    PubMed

    Xing, Lijuan; Ten Brink, Gert H; Chen, Bin; Schmidt, Franz P; Haberfehlner, Georg; Hofer, Ferdinand; Kooi, Bart J; Palasantzas, George

    2016-05-27

    Core-shell structured Fe nanoparticles (NPs) produced by high pressure magnetron sputtering gas condensation were studied using transmission electron microscopy (TEM) techniques, electron diffraction, electron energy-loss spectroscopy (EELS), tomographic reconstruction, and Wulff shape construction analysis. The core-shell structure, which is composed of an Fe core surrounded by a maghemite (γ-Fe2O3) and/or magnetite (Fe3O4) shell, was confirmed by fast Fourier transform (FFT) analysis combined with EELS. It was found that the particle size and shape strongly depend on the gas environment. Moreover, extensive analysis showed that NPs with a size between 10-20 nm possess a truncated cubic morphology, which is confined by the 6 {100} planes that are truncated by the 12 {110} planes at different degrees. For NPs larger than 20 nm, the rhombic dodecahedron defined by the 12 {110} planes is the predominant crystal shape, while truncated rhombic dodecahedrons, as well as non-truncated and truncated cubic NPs, were also observed. The NPs without truncation showed a characteristic inward relaxation indicating that besides thermodynamics kinetics also plays a crucial role during particle growth.

  10. Coat Protein-Dependent Behavior of Poly(ethylene glycol) Tails in Iron Oxide Core Virus-like Nanoparticles.

    PubMed

    Malyutin, Andrey G; Cheng, Hu; Sanchez-Felix, Olivia R; Carlson, Kenneth; Stein, Barry D; Konarev, Petr V; Svergun, Dmitri I; Dragnea, Bogdan; Bronstein, Lyudmila M

    2015-06-10

    Here we explore the formation of virus-like nanoparticles (VNPs) utilizing 22-24 nm iron oxide nanoparticles (NPs) as cores and proteins derived from viral capsids of brome mosaic virus (BMV) or hepatitis B virus (HBV) as shells. To accomplish that, hydrophobic FeO/Fe3O4 NPs prepared by thermal decomposition of iron oleate were coated with poly(maleic acid-alt-octadecene) modified with poly(ethylene glycol) (PEG) tails of different lengths and grafting densities. MRI studies show high r2/r1 relaxivity ratios of these NPs that are practically independent of the polymer coating type. The versatility and flexibility of the viral capsid protein are on display as they readily form shells that exceed their native size. The location of the long PEG tails upon shell formation was investigated by electron microscopy and small-angle X-ray scattering. PEG tails were located differently in the BMV and HBV VNPs, with the BMV VNPs preferentially entrapping the tails in the interior and the HBV VNPs allowing the tails to extend through the capsid, which highlights the differences between intersubunit interactions in these two icosahedral viruses. The robustness of the assembly reaction and the protruding PEG tails, potentially useful in modulating the immune response, make the systems introduced here a promising platform for biomedical applications. PMID:25989427

  11. Iron oxide core oil-in-water emulsions as a multifunctional nanoparticle platform for tumor targeting and imaging

    PubMed Central

    Jarzyna, Peter A.; Skajaa, Torjus; Gianella, Anita; Cormode, David P.; Samber, Dan D.; Dickson, Stephen D.; Chen, Wei; Griffioen, Arjan W.; Fayad, Zahi A.; Mulder, Willem J. M.

    2009-01-01

    Nanoemulsions are increasingly investigated for the delivery of hydrophobic drugs to improve their bioavailability or make their administration possible. In the current study, oil-in-water emulsions with three different mean diameters (30, 60, and 95 nm) were developed as a new multimodality nanoparticle platform for tumor targeting and imaging. To that aim, hydrophobically coated iron oxide particles were included in the soybean oil core of the nanoemulsions to enable their detection with magnetic resonance imaging (MRI), while the conjugation of a near infrared fluorophore allowed optical imaging. The accumulation of this novel nanocomposite in subcutaneous human tumors in nude mice was demonstrated with MRI and fluorescence imaging in vivo, and with Perl’s staining of histological tumor sections ex vivo. PMID:19783295

  12. New Approach to Selective Stem Cell Sorting: Separation of Undifferentiated Stem Cells from Differentiated Stem Cells by Using Iron Oxide Core Shell Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kisa, Fikrullah

    An alternative approach to stem cell enrichment in another words sorting methods without changing the microenvironment of the cells to avoid the detrimental effects of present cell sorting methods by adopting iron-oxide gold (cFeAu) core-shell nanoparticles (NPs) is the focus of this thesis. Each chapter of this thesis focuses on different preliminary research in order to engender the adoption of cFeAu NPs for the selective killing of the mouse embryonic stem cells that are immunolabeled with the nanoparticles. The first part of the research focuses on the synthesis of superparamagnetic iron-oxide nanoparticles with the co-precipitation method and coating the nanoparticles with colloidal gold (cAu) to stabilize the characteristics of the nanoparticles. Detailed information regarding the chemistry of iron-oxide nanoparticles, common synthesis methods, and some of the factors that affect nanoparticle growth and synthesis have been investigated. The heating ability of the nanoparticles under an oscillating magnetic field (OMF) and the size distribution of the particles under a transmission electron microscope (TEM) are shown. The second part of the research focuses on selectively killing the RAW 264.7 macrophages which have internalized the synthesized nanoparticles in order to prove the biocompatibility and effectiveness of the nanoparticles. The particles' effect on the cells, the mechanism of killing, and the effectiveness of nanoparticles coated with colloidal gold and bovine serum albumin are investigated. The last part of the research focuses on effectively labeling the mESCs with a specific antibody conjugated to cFeAu nanoparticles that has an affinity to stage specific embryonic antigen 1 (SSEA-1). The influence of the OMF and the effects of immunolabeling on cell growth were investigated. The successful conjugation of the nanoparticles onto the cell surface is shown under scanning electron microscope. The damage inflicted by the nanoparticles on the cells

  13. Magnetic-Plasmonic Core-Shell Nanoparticles

    PubMed Central

    Levin, Carly S.; Hofmann, Cristina; Ali, Tamer A.; Kelly, Anna T.; Morosan, Emilia; Nordlander, Peter; Whitmire, Kenton H.; Halas, Naomi J.

    2013-01-01

    Nanoparticles composed of magnetic cores with continuous Au shell layers simultaneously possess both magnetic and plasmonic properties. Faceted and tetracubic nanocrystals consisting of wüstite with magnetite-rich corners and edges retain magnetic properties when coated with an Au shell layer, with the composite nanostructures showing ferrimagnetic behavior. The plasmonic properties are profoundly influenced by the high dielectric constant of the mixed-iron-oxide nanocrystalline core. A comprehensive theoretical analysis that examines the geometric plasmon tunability over a range of core permittivities enables us to identify the dielectric properties of the mixed-oxide magnetic core directly from the plasmonic behavior of the core-shell nanoparticle. PMID:19441794

  14. Study of iron nanoparticle melting

    NASA Astrophysics Data System (ADS)

    Fedorov, A. V.; Shulgin, A. V.; Lavruk, S. A.

    2016-10-01

    In paper melting process of iron nanoparticles was investigated with molecular dynamics method. Melting temperatures was found for particles with radius from 1.5 to 4 nm. Results match with data of other authors. Heat capacity was calculated based on investigation of caloric curves. Dependence between heat capacity and temperature for different size of nanoparticles was approximated. Heat conductivity of iron nanoparticles was calculated.

  15. Synthesis of carbon-encapsulated iron nanoparticles via solid state reduction of iron oxide nanoparticles

    SciTech Connect

    Bystrzejewski, M.

    2011-06-15

    The encapsulation of iron nanoparticles in protective carbon cages leads to unique hybrid core-shell nanomaterials. Recent literature reports suggest that such nanocomposites can be obtained in a relatively simple process involving the solid state carbothermal reduction of iron oxide nanoparticles. This approach is very attractive because it does not require advanced equipment and consumes less energy in comparison to widely used plasma methods. The presented more-in-depth study shows that the carbothermal approach is sensitive to temperature and the process yield strongly depends on the morphology and crystallinity of the carbon material used as a reductant. - Graphical abstract: Reduction of iron oxide nanoparticles by carbon black at 1200 deg. C yields well crystallized carbon-encapsulated iron nanoparticles. Highlights: > Carbon-encapsulated iron nanoparticles were synthesized by carbothermal reduction of iron oxide nanoparticles. > The process has the highest selectivity at 1200 C. > Lower temperatures result in iron oxide nanoparticles wrapped in carbon matrix. > The encapsulation rate of Fe at 1200 deg. C was found to be 15%.

  16. 34. DESPATCH CORE OVENS, GREY IRON FOUNDRY CORE ROOM, BAKES ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    34. DESPATCH CORE OVENS, GREY IRON FOUNDRY CORE ROOM, BAKES CORES THAT ARE NOT MADE ON HEATED OR COLD BOX CORE MACHINES, TO SET BINDING AGENTS MIXED WITH THE SAND CREATING CORES HARD ENOUGH TO WITHSTAND THE FLOW OF MOLTEN IRON INSIDE A MOLD. - Stockham Pipe & Fittings Company, Grey Iron Foundry, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  17. Comparison of the Properties of γ-Fe_22O3 Nanoparticles Synthesized Inside of Ferritin Protein Cages to the Native Iron Oxy-hydroxide Cores

    NASA Astrophysics Data System (ADS)

    Gilmore, Keith

    2004-03-01

    The structural and magnetic properties of native iron oxy-hydroxide in ferritin and γ-Fe_22O3 artificially mineralized inside of horse spleen ferritin have been compared. While the native material has been studied in detail, little work has been done on artificially mineralized materials. Such synthetic materials can form highly uniform, self assembling systems which can be used in magnetic recording and other applications. We show that the mineralized iron oxide has more favorable magnetic properties for these applications than the native material. Specifically, through XAS and XAFS spectra, we conclude that the native cores are highly disordered and non-uniform while the mineralized sample is uniform and ordered γ-Fe_22O_3. γ-Fe_22O3 is ferrimagnetic while it has been shown that the native material is antiferromagnetic. Alternating current susceptibility measurements reveal that, relative to the native material, the mineralized sample has a higher blocking temperature by a factor of two, is about 20 times more susceptible to magnetization, and has a larger anisotropy energy by 150also been extracted from the AC data indicating a mean diameter of 5 nm for the native cores and 6 nm for the mineralized cores. DC magnetic measurements provide supporting evidence of the magnetic structure, blocking temperatures, and crystalline disorder of the two samples. This study demonstrates the feasibility of using of biological containers as reaction vessels to synthesize uniform ensembles of novel magnetic nanoparticles.

  18. Acid monolayer functionalized iron oxide nanoparticle catalysts

    NASA Astrophysics Data System (ADS)

    Ikenberry, Myles

    Superparamagnetic iron oxide nanoparticle functionalization is an area of intensely active research, with applications across disciplines such as biomedical science and heterogeneous catalysis. This work demonstrates the functionalization of iron oxide nanoparticles with a quasi-monolayer of 11-sulfoundecanoic acid, 10-phosphono-1-decanesulfonic acid, and 11-aminoundecanoic acid. The carboxylic and phosphonic moieties form bonds to the iron oxide particle core, while the sulfonic acid groups face outward where they are available for catalysis. The particles were characterized by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), potentiometric titration, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray photoelectron spectrometry (XPS), and dynamic light scattering (DLS). The sulfonic acid functionalized particles were used to catalyze the hydrolysis of sucrose at 80° and starch at 130°, showing a higher activity per acid site than the traditional solid acid catalyst Amberlyst-15, and comparing well against results reported in the literature for sulfonic acid functionalized mesoporous silicas. In sucrose catalysis reactions, the phosphonic-sulfonic nanoparticles (PSNPs) were seen to be incompletely recovered by an external magnetic field, while the carboxylic-sulfonic nanoparticles (CSNPs) showed a trend of increasing activity over the first four recycle runs. Between the two sulfonic ligands, the phosphonates produced a more tightly packed monolayer, which corresponded to a higher sulfonic acid loading, lower agglomeration, lower recoverability through application of an external magnetic field, and higher activity per acid site for the hydrolysis of starch. Functionalizations with 11-aminoundecanoic acid resulted in some amine groups binding to the surfaces of iron oxide nanoparticles. This amine binding is commonly ignored in iron oxide

  19. Characterization of tetraethylene glycol passivated iron nanoparticles

    NASA Astrophysics Data System (ADS)

    Nunes, Eloiza da Silva; Viali, Wesley Renato; da Silva, Sebastião William; Coaquira, José Antonio Huamaní; Garg, Vijayendra Kumar; de Oliveira, Aderbal Carlos; Morais, Paulo César; Jafelicci Júnior, Miguel

    2014-10-01

    The present study describes the synthesis and characterization of iron@iron oxide nanoparticles produced by passivation of metallic iron in tetraethylene glycol media. Structural and chemical characterizations were performed using transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Mössbauer spectroscopy. Pomegranate-like core@shell nanoparticulate material in the size range of 90-120 nm was obtained. According to quantitative phase analysis using Rietveld structure refinement the synthesized iron oxide was identified as magnetite (Fe3O4) whereas the iron to magnetite mass fractions was found to be 47:53. These findings are in good agreement with the data obtained from Mössbauer and thermal gravimetric analysis (TGA). The XPS data revealed the presence of a surface organic layer with higher hydrocarbon content, possibly due to the tetraethylene glycol thermal degradation correlated with iron oxidation. The room-temperature (300 K) saturation magnetization measured for the as-synthesized iron and for the iron-iron oxide were 145 emu g-1 and 131 emu g-1, respectively. The measured saturation magnetizations are in good agreement with data obtained from TEM, XRD and Mössbauer spectroscopy.

  20. 33. BENCH CORE STATION, GREY IRON FOUNDRY CORE ROOM WHERE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    33. BENCH CORE STATION, GREY IRON FOUNDRY CORE ROOM WHERE CORE MOLDS WERE HAND FILLED AND OFTEN PNEUMATICALLY COMPRESSED WITH A HAND-HELD RAMMER BEFORE THEY WERE BAKED. - Stockham Pipe & Fittings Company, Grey Iron Foundry, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  1. The use of the core-shell structure of zero-valent iron nanoparticles (NZVI) for long-term removal of sulphide in sludge during anaerobic digestion.

    PubMed

    Su, Lianghu; Zhen, Guangyin; Zhang, Longjiang; Zhao, Youcai; Niu, Dongjie; Chai, Xiaoli

    2015-12-01

    A core-shell structure results in zero-valent iron nanoparticles (NZVI) with manifold functional properties. In this study, the long-term effects of NZVI on hydrogen sulphide removal in an anaerobic sludge digester were investigated. Within 20 days, the average hydrogen sulphide content in the biogas was successfully reduced from 300 (or 3620 of sulphate-rich sludge) mg Nm(-3) to 6.1 (121), 0.9 (3.3) and 0.5 (1.3) mg Nm(-3) in the presence of 0.05, 0.10 and 0.20% (wt) NZVI, respectively. Methane yield was enhanced at the low NZVI dose (0.05-0.10%) but decreased at the elevated dose (0.20%). Methane production and volatile solid degradation analyses implied that doses of 0.5-0.10% NZVI could accelerate sludge stabilization during anaerobic digestion. The phosphorus fractionation profile suggested that methane production could be inhibited at the elevated NZVI dose, partly due to the limited availability of soluble phosphorus due to the immobilization of bioavailable-P through the formation of vivianite. An analysis of the reducible inorganic sulphur species revealed that the elimination of hydrogen sulphide occurred via the reaction between hydrogen sulphide and the oxide shell of NZVI, which mainly formed FeS and some FeS2 and S(0). PMID:26565792

  2. Multifunctional iron oxide nanoparticles for biomedical applications

    NASA Astrophysics Data System (ADS)

    Bloemen, M.; Denis, C.; Van Stappen, T.; De Meester, L.; Geukens, N.; Gils, A.; Verbiest, T.

    2015-03-01

    Multifunctional nanoparticles have attracted a lot of attention since they can combine interesting properties like magnetism, fluorescence or plasmonic effects. As a core material, iron oxide nanoparticles have been the subject of intensive research. These cost-effective and non-toxic particles are used nowadays in many applications. We developed a heterobifunctional PEG ligand that can be used to introduce functional groups (carboxylic acids) onto the surface of the NP. Via click chemistry, a siloxane functionality was added to this ligand, for a subsequent covalent ligand exchange reaction. The functionalized nanoparticles have an excellent colloidal stability in complex environments like buffers and serum or plasma. Antibodies were coupled to the introduced carboxylic acids and these NP-antibody bioconjugates were brought into contact with Legionella bacteria for magnetic separation experiments.

  3. Tannin biosynthesis of iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Herrera-Becerra, R.; Rius, J. L.; Zorrilla, C.

    2010-08-01

    In this work, iron oxide nanoparticles synthesized with gallic acid and tannic acid are characterized using High-Resolution Transmission Electron Microscopy (HRTEM). Its size, form, and structure are compared with nanoparticles obtained previously using alfalfa biomass in order to find a simpler, consistent, and environmentally friendly method in the production of iron oxide nanoparticles.

  4. Biocompatible core-shell magnetic nanoparticles for cancer treatment

    SciTech Connect

    Sharma, Amit M.; Qiang, You; Meyer, Daniel R.; Souza, Ryan; Mcconnaughoy, Alan; Muldoon, Leslie; Baer, Donald R.

    2008-04-01

    Non-toxic magnetic nanoparticles (MNPs) have expanded the treatment delivery options in the medical world. With a size range from 2 to 200 nm MNPs can be compiled with most of the small cells and tissues in living body. Monodispersive iron-iron oxide core shell nanoparticles were prepared in our novel cluster deposition system. This unique method of preparing the core shell MNPs gives nanoparticles very high magnetic moment. We tested the nontoxicity and uptake of MNPs coated with/without dextrin by incubating them with rat LX-1 small cell lung cancer cells (SCLC). Since core iron enhances the heating effect [7] the rate of oxidation of iron nanoparticles was tested in deionized water at certain time interval. Both coated and noncoated MNPs were successfully uptaken by the cells, indicating that the nanoparticles were not toxic. The stability of MNPs was verified by X-ray diffraction (XRD) scan after 0, 24, 48, 96, 204 hours. Due to the high magnetic moment offered by MNPs produced in our lab, we predict that even in low applied external alternating field desired temperature can be reached in cancer cells in comparison to the commercially available nanoparticles. Moreover, our MNPs do not require additional anti-coagulating agents and provide a cost effective means of treatment with significantly lower dosage in the body in comparison to commercially available nanoparticles.

  5. The toxicity and distribution of iron oxide-zinc oxide core-shell nanoparticles in C57BL/6 mice after repeated subcutaneous administration.

    PubMed

    Yun, Jun-Won; Yoon, Jung-Hee; Kang, Byeong-Cheol; Cho, Nam-Hyuk; Seok, Seung Hyeok; Min, Seung-Kee; Min, Ji Hyun; Che, Jeong-Hwan; Kim, Young Keun

    2015-06-01

    Therapeutic cancer vaccines promote immune responses by delivering tumour-specific antigens. Recently, we developed iron oxide (Fe3 O4 )-zinc oxide (ZnO) core-shell nanoparticles (CSNPs) as carriers for antigen delivery into dendritic cells (DCs), and the CSNPs were injected subcutaneously into C57BL/6 mice to examine the systemic toxicity, tissue distribution and excretion of the CSNPs. The doses injected were 0, 4, 20 and 200 mg kg(-1) weekly for 4 weeks. No significant changes were observed after the CSNPs administration with respect to mortality, clinical observations, body weight, food intake, water consumption, urinalysis, haematology, serum biochemistry,and organ weights. A dose-dependent increase in granulomatous inflammation was observed at the injection site of the CSNP-treated animals, but no other histopathological lesions in other organs could be attributed to the CSNPs. The Zn concentration, which is an indicator for CSNPs, was not significantly higher in the sampled tissues, urine, or faeces after the CSNP injection. In contrast, the Zn concentration at the subcutaneous skin of the site injected with the CSNPs increased in a dose-dependent manner, along with a macroscopic deposition of the CSNPs. The CSNP residue at the injection site resulted in a foreign body response with the appearance of macrophage infiltration, but otherwise did not show any systemic distribution or toxicity at up to 200 mg kg(-1) during this study. In conclusion, CSNPs could be used as good antigen carriers for DC-based immunotherapy, although further study is needed to completely clear the residue of the CSNPs at the injection site.

  6. Synthesis, properties, and applications of iron nanoparticles.

    SciTech Connect

    Huber, Dale L.

    2005-01-01

    Iron, the most ubiquitous of the transition metals and the fourth most plentiful element in the Earths crust, is the structural backbone of our modern infrastructure. It is therefore ironic that as a nanoparticle, iron has been somewhat neglected in favor of its own oxides, as well as other metals such as cobalt, nickel, gold, and platinum. This is unfortunate, but understandable. Irons reactivity is important in macroscopic applications (particularly rusting), but is a dominant concern at the nanoscale. Finely divided iron has long been known to be pyrophoric, which is a major reason that iron nanoparticles have not been more fully studied to date. This extreme reactivity has traditionally made iron nanoparticles difficult to study and inconvenient for practical applications. Iron however has a great deal to offer at the nanoscale, including very potent magnetic and catalytic properties. Recent work has begun to take advantage of irons potential, and work in this field appears to be blossoming.

  7. Structural and magnetic properties of iron nanowires and iron nanoparticles fabricated through a reduction reaction.

    PubMed

    Krajewski, Marcin; Lin, Wei Syuan; Lin, Hong Ming; Brzozka, Katarzyna; Lewinska, Sabina; Nedelko, Natalia; Slawska-Waniewska, Anna; Borysiuk, Jolanta; Wasik, Dariusz

    2015-01-01

    The main goal of this work is to study the structural and magnetic properties of iron nanowires and iron nanoparticles, which have been fabricated in almost the same processes. The only difference in the synthesis is an application of an external magnetic field in order to form the iron nanowires. Both nanomaterials have been examined by means of transmission electron microscopy, energy dispersive X-ray spectrometry, X-ray diffractometry and Mössbauer spectrometry to determine their structures. Structural investigations confirm that obtained iron nanowires as well as nanoparticles reveal core-shell structures and they are composed of crystalline iron cores that are covered by amorphous or highly defected phases of iron and iron oxides. Magnetic properties have been measured using a vibrating sample magnetometer. The obtained values of coercivity, remanent magnetization, saturation magnetization as well as Curie temperature differ for both studied nanostructures. Higher values of magnetizations are observed for iron nanowires. At the same time, coercivity and Curie temperature are higher for iron nanoparticles. PMID:26425415

  8. Evaluating the mobility of polymer-stabilised zero-valent iron nanoparticles and their potential to co-transport contaminants in intact soil cores.

    PubMed

    Chekli, L; Brunetti, G; Marzouk, E R; Maoz-Shen, A; Smith, E; Naidu, R; Shon, H K; Lombi, E; Donner, E

    2016-09-01

    The use of zero-valent iron nanoparticles (nZVI) has been advocated for the remediation of both soils and groundwater. A key parameter affecting nZVI remediation efficacy is the mobility of the particles as this influences the reaction zone where remediation can occur. However, by engineering nZVI particles with increased stability and mobility we may also inadvertently facilitate nZVI-mediated contaminant transport away from the zone of treatment. Previous nZVI mobility studies have often been limited to model systems as the presence of background Fe makes detection and tracking of nZVI in real systems difficult. We overcame this problem by synthesising Fe-59 radiolabelled nZVI. This enabled us to detect and quantify the leaching of nZVI-derived Fe-59 in intact soil cores, including a soil contaminated by Chromated-Copper-Arsenate. Mobility of a commercially available nZVI was also tested. The results showed limited mobility of both nanomaterials; <1% of the injected mass was eluted from the columns and most of the radiolabelled nZVI remained in the surface soil layers (the primary treatment zone in this contaminated soil). Nevertheless, the observed breakthrough of contaminants and nZVI occurred simultaneously, indicating that although the quantity transported was low in this case, nZVI does have the potential to co-transport contaminants. These results show that direct injection of nZVI into the surface layers of contaminated soils may be a viable remediation option for soils such as this one, in which the mobility of nZVI below the injection/remediation zone was very limited. This Fe-59 experimental approach can be further extended to test nZVI transport in a wider range of contaminated soil types and textures and using different application methods and rates. The resulting database could then be used to develop and validate modelling of nZVI-facilitated contaminant transport on an individual soil basis suitable for site specific risk assessment prior to n

  9. Evaluating the mobility of polymer-stabilised zero-valent iron nanoparticles and their potential to co-transport contaminants in intact soil cores.

    PubMed

    Chekli, L; Brunetti, G; Marzouk, E R; Maoz-Shen, A; Smith, E; Naidu, R; Shon, H K; Lombi, E; Donner, E

    2016-09-01

    The use of zero-valent iron nanoparticles (nZVI) has been advocated for the remediation of both soils and groundwater. A key parameter affecting nZVI remediation efficacy is the mobility of the particles as this influences the reaction zone where remediation can occur. However, by engineering nZVI particles with increased stability and mobility we may also inadvertently facilitate nZVI-mediated contaminant transport away from the zone of treatment. Previous nZVI mobility studies have often been limited to model systems as the presence of background Fe makes detection and tracking of nZVI in real systems difficult. We overcame this problem by synthesising Fe-59 radiolabelled nZVI. This enabled us to detect and quantify the leaching of nZVI-derived Fe-59 in intact soil cores, including a soil contaminated by Chromated-Copper-Arsenate. Mobility of a commercially available nZVI was also tested. The results showed limited mobility of both nanomaterials; <1% of the injected mass was eluted from the columns and most of the radiolabelled nZVI remained in the surface soil layers (the primary treatment zone in this contaminated soil). Nevertheless, the observed breakthrough of contaminants and nZVI occurred simultaneously, indicating that although the quantity transported was low in this case, nZVI does have the potential to co-transport contaminants. These results show that direct injection of nZVI into the surface layers of contaminated soils may be a viable remediation option for soils such as this one, in which the mobility of nZVI below the injection/remediation zone was very limited. This Fe-59 experimental approach can be further extended to test nZVI transport in a wider range of contaminated soil types and textures and using different application methods and rates. The resulting database could then be used to develop and validate modelling of nZVI-facilitated contaminant transport on an individual soil basis suitable for site specific risk assessment prior to n

  10. Improved Thermoplastic/Iron-Particle Transformer Cores

    NASA Technical Reports Server (NTRS)

    Wincheski, Russell A.; Bryant, Robert G.; Namkung, Min

    2004-01-01

    A method of fabricating improved transformer cores from composites of thermoplastic matrices and iron-particles has been invented. Relative to commercially available laminated-iron-alloy transformer cores, the cores fabricated by this method weigh less and are less expensive. Relative to prior polymer-matrix/ iron-particle composite-material transformer cores, the cores fabricated by this method can be made mechanically stronger and more magnetically permeable. In addition, whereas some prior cores have exhibited significant eddy-current losses, the cores fabricated by this method exhibit very small eddy-current losses. The cores made by this method can be expected to be attractive for use in diverse applications, including high-signal-to-noise transformers, stepping motors, and high-frequency ignition coils. The present method is a product of an experimental study of the relationships among fabrication conditions, final densities of iron particles, and mechanical and electromagnetic properties of fabricated cores. Among the fabrication conditions investigated were molding pressures (83, 104, and 131 MPa), and molding temperatures (250, 300, and 350 C). Each block of core material was made by uniaxial-compression molding, at the applicable pressure/temperature combination, of a mixture of 2 weight percent of LaRC (or equivalent high-temperature soluble thermoplastic adhesive) with 98 weight percent of approximately spherical iron particles having diameters in the micron range. Each molded block was cut into square cross-section rods that were used as core specimens in mechanical and electromagnetic tests. Some of the core specimens were annealed at 900 C and cooled slowly before testing. For comparison, a low-carbon-steel core was also tested. The results of the tests showed that density, hardness, and rupture strength generally increased with molding pressure and temperature, though the correlation was rather weak. The weakness of the correlation was attributed to

  11. Characterization of zero-valent iron nanoparticles.

    PubMed

    Sun, Yuan-Pang; Li, Xiao-qin; Cao, Jiasheng; Zhang, Wei-xian; Wang, H Paul

    2006-06-30

    The iron nanoparticle technology has received considerable attention for its potential applications in groundwater treatment and site remediation. Recent studies have demonstrated the efficacy of zero-valent iron nanoparticles for the transformation of halogenated organic contaminants and heavy metals. In this work, we present a systematic characterization of the iron nanoparticles prepared with the method of ferric iron reduction by sodium borohydride. Particle size, size distribution and surface composition were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), high-resolution X-ray photoelectron spectroscopy (HR-XPS), X-ray absorption near edge structure (XANES) and acoustic/electroacoustic spectrometry. BET surface area, zeta (zeta) potential, iso-electric point (IEP), solution Eh and pH were also measured. Methods and results presented may foster better understanding, facilitate information exchange, and contribute to further research and development of iron nanoparticles for environmental and other applications.

  12. Structural and magnetic properties of iron nanowires and iron nanoparticles fabricated through a reduction reaction

    PubMed Central

    Lin, Wei Syuan; Lin, Hong Ming; Brzozka, Katarzyna; Lewinska, Sabina; Nedelko, Natalia; Slawska-Waniewska, Anna; Borysiuk, Jolanta; Wasik, Dariusz

    2015-01-01

    Summary The main goal of this work is to study the structural and magnetic properties of iron nanowires and iron nanoparticles, which have been fabricated in almost the same processes. The only difference in the synthesis is an application of an external magnetic field in order to form the iron nanowires. Both nanomaterials have been examined by means of transmission electron microscopy, energy dispersive X-ray spectrometry, X-ray diffractometry and Mössbauer spectrometry to determine their structures. Structural investigations confirm that obtained iron nanowires as well as nanoparticles reveal core–shell structures and they are composed of crystalline iron cores that are covered by amorphous or highly defected phases of iron and iron oxides. Magnetic properties have been measured using a vibrating sample magnetometer. The obtained values of coercivity, remanent magnetization, saturation magnetization as well as Curie temperature differ for both studied nanostructures. Higher values of magnetizations are observed for iron nanowires. At the same time, coercivity and Curie temperature are higher for iron nanoparticles. PMID:26425415

  13. Synthesis and characterization of iron based nanoparticles for novel applications

    NASA Astrophysics Data System (ADS)

    Khurshid, Hafsa

    The work in this thesis has been focused on the fabrication and characterization of iron based nanoparticles with controlled size and morphology with the aim: (i) to investigate their properties for potential applications in MICR toners and biomedical field and (ii) to study finite size effects on the magnetic properties of the nanoparticles. For the biomedical applications, core/shell structured iron/iron-oxide and hollow shell nanoparticles were synthesized by thermal decomposition of iron organometallic compounds [Fe(CO)5] at high temperature. Core/shell structured iron/iron-oxide nanoparticles have been prepared in the presence of oleic acid and oleylamine. Particle size and composition was controlled by varying the reaction parameters during synthesis. The as-made particles are hydrophobic and not dispersible in water. Water dispersibility was achieved by ligand exchange a with double hydrophilic diblock copolymer. Relaxometery measurements of the transverse relaxation time T2 of the nanoparticles solution at 3 Tesla confirm that the core/shell nanoparticles are an excellent MRI contrast agent using T2 weighted imaging sequences. In comparison to conventionally used iron oxide nanoparticles, iron/iron-oxide core/shell nanoparticles offer four times stronger T2 shortening effect at comparable core size due to their higher magnetization. The magnetic properties were studied as a function of particle size, composition and morphology. Hollow nanostructures are composed of randomly oriented grains arranged together to make a shell layer and make an interesting class of materials. The hollow morphology can be used as an extra degree of freedom to control the magnetic properties. Owing to their hollow morphology, they can be used for the targeted drug delivery applications by filling the drug inside their cavity. For the magnetic toners applications, particles were synthesized by chemically reducing iron salt using sodium borohydride and then coated with polyethylene

  14. Properties of iron under core conditions

    NASA Astrophysics Data System (ADS)

    Brown, J. M.

    2003-04-01

    Underlying an understanding of the geodynamo and evolution of the core is knowledge of the physical and chemical properties of iron and iron mixtures under high pressure and temperature conditions. Key properties include the viscosity of the fluid outer core, thermal diffusivity, equations-of-state, elastic properties of solid phases, and phase equilibria for iron and iron-dominated mixtures. As is expected for work that continues to tax technological and intellectual limits, controversy has followed both experimental and theoretical progress in this field. However, estimates for the melting temperature of the inner core show convergence and the equation-of-state for iron as determined in independent experiments and theories are in remarkable accord. Furthermore, although the structure and elastic properties of the solid inner-core phase remains uncertain, theoretical and experimental underpinnings are better understood and substantial progress is likely in the near future. This talk will focus on an identification of properties that are reasonably well known and those that merit further detailed study. In particular, both theoretical and experimental (static and shock wave) determinations of the density of iron under extreme conditions are in agreement at the 1% or better level. The behavior of the Gruneisen parameter (which determines the geothermal gradient and controls much of the outer core heat flux) is constrained by experiment and theory under core conditions for both solid and liquid phases. Recent experiments and theory are suggestive of structure or structures other than the high-pressure hexagonal close-packed (HCP) phase. Various theories and experiments for the elasticity of HCP iron remain in poor accord. Uncontroversial constraints on core chemistry will likely never be possible. However, reasonable bounds are possible on the basis of seismic profiles, geochemical arguments, and determinations of sound velocities and densities at high pressure and

  15. Synthesis of carbon-coated iron nanoparticles by detonation technique

    SciTech Connect

    Sun, Guilei; Li, Xiaojie; Wang, Qiquan; Yan, Honghao

    2010-05-15

    Carbon-coated iron nanoparticles were synthesized by detonating a mixture of ferrocene, naphthalene and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in an explosion vessel under low vacuum conditions (8.1 kPa). The RDX functioned as an energy source for the decomposition of ferrocene and naphthalene. The carbon-coated iron nanoparticles were formed as soot-like deposits on the inner surface of the reactor, which were characterized by XRD, TEM, HRTEM, Raman spectroscopy and vibrating sample magnetometer. And a portion of the detonation soot was treated with hydrochloric acid. The product was carbon-coated nanoparticles in perfect core-shell structures with graphitic shells and bcc-Fe cores. The detonation technique offers an energy-saving route to the synthesis of carbon-coated nanomaterials.

  16. The synthesis and characterization of iron nanoparticles

    NASA Astrophysics Data System (ADS)

    Bennett, Tyler

    Nanoparticle synthesis has garnered attention for technological applications for catalysts, industrial processing, and medical applications. The size ranges for these is in the particles nanostructural domain. Pure iron nanoparticles have been of particular interest for their reactivity and relative biological inertness. Applications include cancer treatment and carrying medicine to a relevant site. Unfortunately, because of their reactivity, pure iron nanoparticles have been difficult to study. This is because of their accelerated tendency to form oxides in air, due to the increased surface area to volume ratio. Using synthesis processes with polyphenols or long chain amines, air stable iron nanoparticles have been produced with a diameter size range of ~ 2 to about ~10 nm, but apparently have transformed due to internal pressure and crystallographic defects to the FCC phase. The FCC crystals have been seen to form icosahedral and decahedral shapes. This size is within the range for use as a catalyst for the growth of both carbon nanotubes and boron nitride nanotubes as well for biomedical applications. The advantages of these kinds of catalysts are that nanotube growth can be for the first time separated from the catalyst formation. Additionally, the catalyst size can be preselected for a certain size nanotube to grow. In summary: (1) we found the size distributions of nanoparticles for various synthesis processes, (2) we discovered the right size range for growth of nanotubes from the iron nanoparticles, (3) the nanoparticles are under a very high internal pressure, (4) the nanoparticles are in the FCC phase, (5) they appear to be in icosahedral and decahedral structures, (6) they undergo room temperature twinning, (7) the FCC crystals are distorted due to carbon in octahedral sites, (8) the iron nanoparticles are stable in air, (9) adding small amounts of copper make the iron nanoparticles smaller.

  17. Zero-valent iron nanoparticles preparation

    SciTech Connect

    Oropeza, S.; Corea, M.; Gómez-Yáñez, C.; Cruz-Rivera, J.J.; Navarro-Clemente, M.E.

    2012-06-15

    Graphical abstract: Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH{sub 3}){sub 3}){sub 2}]{sub 2}] at room temperature and a pressure of 3 atm. The synthesized nanoparticles were spherical and had diameters less than 5 nm. Highlights: ► Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH{sub 3}){sub 3}){sub 2}]{sub 2}]. ► The conditions of reaction were at room temperature and a pressure of 3 atm. ► The synthesized nanoparticles were spherical and had diameters less than 5 nm. -- Abstract: Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH{sub 3}){sub 3}){sub 2}]{sub 2}] at room temperature and a pressure of 3 atm. To monitor the reaction, a stainless steel pressure reactor lined with PTFE and mechanically stirred was designed. This design allowed the extraction of samples at different times, minimizing the perturbation in the system. In this way, the shape and the diameter of the nanoparticles produced during the reaction were also monitored. The results showed the production of zero-valent iron nanoparticles that were approximately 5 nm in diameter arranged in agglomerates. The agglomerates grew to 900 nm when the reaction time increased up to 12 h; however, the diameter of the individual nanoparticles remained almost the same. During the reaction, some byproducts constituted by amino species acted as surfactants; therefore, no other surfactants were necessary.

  18. Fe/Au Core-Shell Nanoparticles for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Sra, Amandeep; Leslie-Pelecky, Diandra

    2009-10-01

    The physical properties of nanoparticles, including size, composition and surface chemistry, greatly influence biological and pharmacological properties and, ultimately, their clinical applications. Superparamagnetic iron oxide nanoparticles are widely used for applications such as MRI contrast agents, drug delivery via magnetic targeting and hyperthermia due to their chemical stability and biocompatibility; however, enhancing the saturation magnetization (Ms) of nanoparticles would produce greater sensitivity. Our design strategy involves a bottom-up wet chemistry approach to the synthesis of Fe nanoparticles. Specific advantages of Fe are the high value of Ms (210 emu/g in bulk) coupled with low toxicity; however, Fe nanoparticles must be protected from oxidation, which causes a dramatic reduction in Ms. To circumvent oxidation, Fe nanoparticles are coated with a Au shell that prevents the oxidation of the magnetic core and also provides the nanoparticles with plasmonic properties for optical stimulation. Ligands of various functionalities can be introduced through the well established Au-thiol surface chemistry for different biomedical applications while maintaining the magnetic functionality of the Fe core. In this presentation, we will discuss the physical, chemical and magnetic properties of our Fe/Au nanoparticles and their resistance to oxidation.

  19. Magnetic iron oxide nanoparticles for biomedical applications.

    PubMed

    Laurent, Sophie; Bridot, Jean-Luc; Elst, Luce Vander; Muller, Robert N

    2010-03-01

    Due to their high magnetization, superparamagnetic iron oxide nanoparticles induce an important decrease in the transverse relaxation of water protons and are, therefore, very efficient negative MRI contrast agents. The knowledge and control of the chemical and physical characteristics of nanoparticles are of great importance. The choice of the synthesis method (microemulsions, sol-gel synthesis, laser pyrolysis, sonochemical synthesis or coprecipitation) determines the magnetic nanoparticle's size and shape, as well as its size distribution and surface chemistry. Nanoparticles can be used for numerous in vivo applications, such as MRI contrast enhancement and hyperthermia drug delivery. New developments focus on targeting through molecular imaging and cell tracking. PMID:21426176

  20. Photon upconversion in core-shell nanoparticles.

    PubMed

    Chen, Xian; Peng, Denfeng; Ju, Qiang; Wang, Feng

    2015-03-21

    Photon upconversion generally results from a series of successive electronic transitions within complex energy levels of lanthanide ions that are embedded in the lattice of a crystalline solid. In conventional lanthanide-doped upconversion nanoparticles, the dopant ions homogeneously distributed in the host lattice are readily accessible to surface quenchers and lose their excitation energy, giving rise to weak and susceptible emissions. Therefore, present studies on upconversion are mainly focused on core-shell nanoparticles comprising spatially confined dopant ions. By doping upconverting lanthanide ions in the interior of a core-shell nanoparticle, the upconversion emission can be substantially enhanced, and the optical integrity of the nanoparticles can be largely preserved. Optically active shells are also frequently employed to impart multiple functionalities to upconversion nanoparticles. Intriguingly, the core-shell design introduces the possibility of constructing novel upconversion nanoparticles by exploiting the energy exchange interactions across the core-shell interface. In this tutorial review, we highlight recent advances in the development of upconversion core-shell nanoparticles, with particular emphasis on the emerging strategies for regulating the interplay of dopant interactions through core-shell nanostructural engineering that leads to unprecedented upconversion properties. The improved control over photon energy conversion will open up new opportunities for biological and energy applications. PMID:25058157

  1. Intratumoral iron oxide nanoparticle hyperthermia and radiation cancer treatment

    NASA Astrophysics Data System (ADS)

    Hoopes, P. J.; Strawbridge, R. R.; Gibson, U. J.; Zeng, Q.; Pierce, Z. E.; Savellano, M.; Tate, J. A.; Ogden, J. A.; Baker, I.; Ivkov, R.; Foreman, A. R.

    2007-02-01

    The potential synergism and benefit of combined hyperthermia and radiation for cancer treatment is well established, but has yet to be optimized clinically. Specifically, the delivery of heat via external arrays /applicators or interstitial antennas has not demonstrated the spatial precision or specificity necessary to achieve appropriate a highly positive therapeutic ratio. Recently, antibody directed and possibly even non-antibody directed iron oxide nanoparticle hyperthermia has shown significant promise as a tumor treatment modality. Our studies are designed to determine the effects (safety and efficacy) of iron oxide nanoparticle hyperthermia and external beam radiation in a murine breast cancer model. Methods: MTG-B murine breast cancer cells (1 x 106) were implanted subcutaneous in 7 week-old female C3H/HeJ mice and grown to a treatment size of 150 mm3 +/- 50 mm3. Tumors were then injected locally with iron oxide nanoparticles and heated via an alternating magnetic field (AMF) generator operated at approximately 160 kHz and 400 - 550 Oe. Tumor growth was monitored daily using standard 3-D caliper measurement technique and formula. specific Mouse tumors were heated using a cooled, 36 mm diameter square copper tube induction coil which provided optimal heating in a 1 cm wide region in the center of the coil. Double dextran coated 80 nm iron oxide nanoparticles (Triton Biosystems) were used in all studies. Intra-tumor, peri-tumor and rectal (core body) temperatures were continually measured throughout the treatment period. Results: Preliminary in vivo nanoparticle-AMF hyperthermia (167 KHz and 400 or 550 Oe) studies demonstrated dose responsive cytotoxicity which enhanced the effects of external beam radiation. AMF associated eddy currents resulted in nonspecific temperature increases in exposed tissues which did not contain nanoparticles, however these effects were minor and not injurious to the mice. These studies also suggest that iron oxide nanoparticle

  2. Chemical design of biocompatible iron oxide nanoparticles for medical applications.

    PubMed

    Ling, Daishun; Hyeon, Taeghwan

    2013-05-27

    Iron oxide nanoparticles are one of the most versatile and safe nanomaterials used in medicine. Recent progress in nanochemistry enables fine control of the size, crystallinity, uniformity, and surface properties of iron oxide nanoparticles. In this review, the synthesis of chemically designed biocompatible iron oxide nanoparticles with improved quality and reduced toxicity is discussed for use in diverse biomedical applications.

  3. Low temperature hydrogenation of iron nanoparticles on graphene

    PubMed Central

    Takahashi, Keisuke; Wang, Yongming; Chiba, Shotaro; Nakagawa, Yuki; Isobe, Shigehito; Ohnuki, Somei

    2014-01-01

    Hydrogenation of iron nanoparticles was performed both computationally and experimentally where previously chemically-bonded iron hydride is considered to be unachievable under ordinary conditions. Density functional theory (DFT) calculations predict that hydrogenated iron nanoparticles are stabilized on a single-layer graphene/Cu substrate. Experimentally, iron nanoparticles were deposited onto a graphene/Cu substrate by vacuum deposition. Hydrogenation was done at 1atm of hydrogen gas and under liquid nitrogen. Mass spectrometry peak confirmed the hydrogen release from hydrogenated iron nanoparticles while a scanning transmission electron microscopy is used in order to link a geometrical shape of iron hydride nanoparticles between experimental and theoretical treatments. The hydrogenated iron nanoparticles were successfully synthesized where hydrogenated iron nanoparticles are stable under ordinary conditions. PMID:24710406

  4. Process to Produce Iron Nanoparticle Lunar Dust Simulant Composite

    NASA Technical Reports Server (NTRS)

    Hung, Ching-cheh; McNatt, Jeremiah

    2010-01-01

    A document discusses a method for producing nanophase iron lunar dust composite simulant by heating a mixture of carbon black and current lunar simulant types (mixed oxide including iron oxide) at a high temperature to reduce ionic iron into elemental iron. The product is a chemically modified lunar simulant that can be attracted by a magnet, and has a surface layer with an iron concentration that is increased during the reaction. The iron was found to be -iron and Fe3O4 nanoparticles. The simulant produced with this method contains iron nanoparticles not available previously, and they are stable in ambient air. These nanoparticles can be mass-produced simply.

  5. 29. DEPENDABLE FORDATHSHELL CORE MACHINES IN THE GREY IRON FOUNDRY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. DEPENDABLE FORDATH-SHELL CORE MACHINES IN THE GREY IRON FOUNDRY INJECTS SAND INTO A CLOSED CORE BOX. SOME OF THE UNITS HEAT THE CORE BOX TO FIX THE RESINS AS THE CORE REMAINS IN THE BOX, OTHERS MERELY SHAPED THE CORE SAND REQUIRING BAKING OF THE CORES TO HARDEN THEM. - Stockham Pipe & Fittings Company, Grey Iron Foundry, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  6. Formation of nanoparticles during laser ablation of an iron target in a liquid

    SciTech Connect

    Sukhov, I A; Simakin, Aleksandr V; Shafeev, Georgii A; Viau, G; Garcia, C

    2012-05-31

    Formation of nanoparticles during laser ablation of a bulk iron target in water and isopropyl alcohol by pulsed near-IR laser radiation has been experimentally investigated. The experiments were performed using a 3-ns neodymium laser and a 100-ns ytterbium fibre laser. A size distribution function is obtained for the nanoparticles, which is peaking near 15 nm. The diffraction patterns of the nanoparticles exhibit pronounced peaks of metallic iron. An analysis of the nanoparticles by transmission electron microscopy shows that in some cases they have a core - shell structure. The nanoparticles formed by laser ablation have pronounced magnetic properties. The absorption spectra of colloids with iron nanoparticles contain peaks, which presumably correspond to the electron plasmon resonance in these particles.

  7. Formation of nanoparticles during laser ablation of an iron target in a liquid

    NASA Astrophysics Data System (ADS)

    Sukhov, I. A.; Simakin, Aleksandr V.; Shafeev, Georgii A.; Viau, G.; Garcia, C.

    2012-05-01

    Formation of nanoparticles during laser ablation of a bulk iron target in water and isopropyl alcohol by pulsed near-IR laser radiation has been experimentally investigated. The experiments were performed using a 3-ns neodymium laser and a 100-ns ytterbium fibre laser. A size distribution function is obtained for the nanoparticles, which is peaking near 15 nm. The diffraction patterns of the nanoparticles exhibit pronounced peaks of metallic iron. An analysis of the nanoparticles by transmission electron microscopy shows that in some cases they have a core — shell structure. The nanoparticles formed by laser ablation have pronounced magnetic properties. The absorption spectra of colloids with iron nanoparticles contain peaks, which presumably correspond to the electron plasmon resonance in these particles.

  8. Fabrication of iron-platinum ferromagnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Elkins, Kevin Eugene

    Fabrication of chemically disordered FePt particles ranging from 2--9 nm with a precision of 1 nm has been achieved through modification of key process variables including surfactant concentration, heating rates and the type of iron precursor. In addition, the shape evolution of the FePt nanoparticles during particle growth can be manipulated to give cubic or rod geometries through changes to the surfactant injection sequence and solvent system. The primary method for synthesis of the disordered FePt nanoparticles is the polyol reduction reported by Fievet et al., which has been modified and used extensively for synthesis of differing nanoparticle systems. Our procedures use platinum acetylacetonate, iron pentacarbonyl or ferric acetylacetonate as precursors for the FePt alloy, oleic acid and oleyl amine for the surfactants, 1,2-hexadecanediol to assist with the reduction of the precursors and either dioctyl ether or phenyl ether for the solvent system. For iron pentacarbonyl based reactions, adjustment of heating rates to reflux temperatures from 1--15°C per minute allows control of FePt particle diameters from 3--8 nm. Substitution of iron pentacarbonyl with ferric acetylacetonate as the iron source results in 2 nm particles. A high platinum to surfactant ratio of 10 to 1 will yield 9 nm FePt particles when iron pentacarbonyl is used as the precursor. For use of these particles in advanced applications, the synthesized particles must be transformed to the L1o phase through annealing at temperatures above 500°C. Inhibition of particle sintering can be avoided through dispersion in a NaCl matrix at a weight ratio of 400 to 1 salt to fcc FePt particles. Production of L1o FePt nanoparticles with high magnetic anisotropy with this process has been successful, allowing the original size and size distribution of the particles.

  9. 30. NATIONAL SHELL CORE MACHINE IN THE GREY IRON FOUNDRY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    30. NATIONAL SHELL CORE MACHINE IN THE GREY IRON FOUNDRY AUTOMATICALLY INJECTS SAND INTO CLOSED, HEATED CORE BOXES THAT SET THE RESINS AND PERMIT A HARDENED CORE TO BE REMOVED BY THE OPERATOR. - Stockham Pipe & Fittings Company, Grey Iron Foundry, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  10. Oral exposure to polystyrene nanoparticles effects iron absorption

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of engineered nanoparticles in food and pharmaceuticals is expected to increase, but the impact of chronic oral exposure to nanoparticles on human health remains unknown. Here, we show that chronic and acute oral exposure to polystyrene nanoparticles can influence iron uptake and iron trans...

  11. DNA nanoparticles with core-shell morphology.

    PubMed

    Chandran, Preethi L; Dimitriadis, Emilios K; Lisziewicz, Julianna; Speransky, Vlad; Horkay, Ferenc

    2014-10-14

    Mannobiose-modified polyethylenimines (PEI) are used in gene therapy to generate nanoparticles of DNA that can be targeted to the antigen-presenting cells of the immune system. We report that the sugar modification alters the DNA organization within the nanoparticles from homogenous to shell-like packing. The depth-dependent packing of DNA within the nanoparticles was probed using AFM nano-indentation. Unmodified PEI-DNA nanoparticles display linear elastic properties and depth-independent mechanics, characteristic of homogenous materials. Mannobiose-modified nanoparticles, however, showed distinct force regimes that were dependent on indentation depth, with 'buckling'-like response that is reproducible and not due to particle failure. By comparison with theoretical studies of spherical shell mechanics, the structure of mannobiosylated particles was deduced to be a thin shell with wall thickness in the order of few nanometers, and a fluid-filled core. The shell-core structure is also consistent with observations of nanoparticle denting in altered solution conditions, with measurements of nanoparticle water content from AFM images, and with images of DNA distribution in Transmission Electron Microscopy.

  12. Hybrid response surface methodology-genetic algorithm optimization of ultrasound-assisted transesterification of waste oil catalysed by immobilized lipase on mesoporous silica/iron oxide magnetic core-shell nanoparticles.

    PubMed

    Karimi, Mahmoud; Keyhani, Alireza; Akram, Asadolah; Rahman, Masoud; Jenkins, Bryan; Stroeve, Pieter

    2013-01-01

    The production ofbiodiesel by transesterification of waste cooking oil (WCO) to partially substitute petroleum diesel is one of the measures for solving the twin problems of environment pollution and energy demand. An environmentally benign process for the enzymatic transesterification using immobilized lipase has attracted considerable attention for biodiesel production. Here, a superparamagnetic, high surface area substrate for lipase immobilization is evaluated. These immobilization substrates are composed of mesoporous silica/superparamagnetic iron oxide core-shell nanoparticles. The effects of methanol ratio to WCO, lipase concentration, water content and reaction time on the synthesis of biodiesel were analysed by utilizing the response surface methodology (RSM). A quadratic response surface equation for calculating fatty acid methyl ester (FAME) content as the objective function was established based on experimental data obtained in accordance with the central composite design. The RSM-based model was then used as the fitness function for genetic algorithm (GA) to optimize its input space. Hybrid RSM-GA predicted the maximum FAME content (91%) at the optimum level of medium variables: methanol ratio to WCO, 4.34; lipase content, 43.6%; water content, 10.22%; and reaction time, 6h. Moreover, the immobilized lipase could be used for four times without considerable loss of the activity. PMID:24350474

  13. Size-Dependent Specific Surface Area of Nanoporous Film Assembled by Core-Shell Iron Nanoclusters

    DOE PAGESBeta

    Antony, Jiji; Nutting, Joseph; Baer, Donald R.; Meyer, Daniel; Sharma, Amit; Qiang, You

    2006-01-01

    Nmore » anoporous films of core-shell iron nanoclusters have improved possibilities for remediation, chemical reactivity rate, and environmentally favorable reaction pathways. Conventional methods often have difficulties to yield stable monodispersed core-shell nanoparticles. We produced core-shell nanoclusters by a cluster source that utilizes combination of Fe target sputtering along with gas aggregations in an inert atmosphere at 7 ∘ C . Sizes of core-shell iron-iron oxide nanoclusters are observed with transmission electron microscopy (TEM). The specific surface areas of the porous films obtained from Brunauer-Emmett-Teller (BET) process are size-dependent and compared with the calculated data.« less

  14. Towards the development of multifunctional chitosan-based iron oxide nanoparticles: Optimization and modelling of doxorubicin release.

    PubMed

    Soares, Paula I P; Sousa, Ana Isabel; Ferreira, Isabel M M; Novo, Carlos M M; Borges, João Paulo

    2016-11-20

    In the present work composite nanoparticles with a magnetic core and a chitosan-based shell were produced as drug delivery systems for doxorubicin (DOX). The results show that composite nanoparticles with a hydrodynamic diameter within the nanometric range are able to encapsulate more DOX than polymeric nanoparticles alone corresponding also to a higher drug release. Moreover the synthesis method of the iron oxide nanoparticles influences the total amount of DOX released and a high content of iron oxide nanoparticles inhibits DOX release. The modelling of the experimental results revealed a release mechanism dominated by Fickian diffusion. PMID:27561489

  15. Towards the development of multifunctional chitosan-based iron oxide nanoparticles: Optimization and modelling of doxorubicin release.

    PubMed

    Soares, Paula I P; Sousa, Ana Isabel; Ferreira, Isabel M M; Novo, Carlos M M; Borges, João Paulo

    2016-11-20

    In the present work composite nanoparticles with a magnetic core and a chitosan-based shell were produced as drug delivery systems for doxorubicin (DOX). The results show that composite nanoparticles with a hydrodynamic diameter within the nanometric range are able to encapsulate more DOX than polymeric nanoparticles alone corresponding also to a higher drug release. Moreover the synthesis method of the iron oxide nanoparticles influences the total amount of DOX released and a high content of iron oxide nanoparticles inhibits DOX release. The modelling of the experimental results revealed a release mechanism dominated by Fickian diffusion.

  16. Polymer/Iron Oxide Nanoparticle Composites--A Straight Forward and Scalable Synthesis Approach.

    PubMed

    Sommertune, Jens; Sugunan, Abhilash; Ahniyaz, Anwar; Bejhed, Rebecca Stjernberg; Sarwe, Anna; Johansson, Christer; Balceris, Christoph; Ludwig, Frank; Posth, Oliver; Fornara, Andrea

    2015-01-01

    Magnetic nanoparticle systems can be divided into single-core nanoparticles (with only one magnetic core per particle) and magnetic multi-core nanoparticles (with several magnetic cores per particle). Here, we report multi-core nanoparticle synthesis based on a controlled precipitation process within a well-defined oil in water emulsion to trap the superparamagnetic iron oxide nanoparticles (SPION) in a range of polymer matrices of choice, such as poly(styrene), poly(lactid acid), poly(methyl methacrylate), and poly(caprolactone). Multi-core particles were obtained within the Z-average size range of 130 to 340 nm. With the aim to combine the fast room temperature magnetic relaxation of small individual cores with high magnetization of the ensemble of SPIONs, we used small (<10 nm) core nanoparticles. The performed synthesis is highly flexible with respect to the choice of polymer and SPION loading and gives rise to multi-core particles with interesting magnetic properties and magnetic resonance imaging (MRI) contrast efficacy.

  17. Polymer/Iron Oxide Nanoparticle Composites—A Straight Forward and Scalable Synthesis Approach

    PubMed Central

    Sommertune, Jens; Sugunan, Abhilash; Ahniyaz, Anwar; Stjernberg Bejhed, Rebecca; Sarwe, Anna; Johansson, Christer; Balceris, Christoph; Ludwig, Frank; Posth, Oliver; Fornara, Andrea

    2015-01-01

    Magnetic nanoparticle systems can be divided into single-core nanoparticles (with only one magnetic core per particle) and magnetic multi-core nanoparticles (with several magnetic cores per particle). Here, we report multi-core nanoparticle synthesis based on a controlled precipitation process within a well-defined oil in water emulsion to trap the superparamagnetic iron oxide nanoparticles (SPION) in a range of polymer matrices of choice, such as poly(styrene), poly(lactid acid), poly(methyl methacrylate), and poly(caprolactone). Multi-core particles were obtained within the Z-average size range of 130 to 340 nm. With the aim to combine the fast room temperature magnetic relaxation of small individual cores with high magnetization of the ensemble of SPIONs, we used small (<10 nm) core nanoparticles. The performed synthesis is highly flexible with respect to the choice of polymer and SPION loading and gives rise to multi-core particles with interesting magnetic properties and magnetic resonance imaging (MRI) contrast efficacy. PMID:26307966

  18. Polymer/Iron Oxide Nanoparticle Composites--A Straight Forward and Scalable Synthesis Approach.

    PubMed

    Sommertune, Jens; Sugunan, Abhilash; Ahniyaz, Anwar; Bejhed, Rebecca Stjernberg; Sarwe, Anna; Johansson, Christer; Balceris, Christoph; Ludwig, Frank; Posth, Oliver; Fornara, Andrea

    2015-01-01

    Magnetic nanoparticle systems can be divided into single-core nanoparticles (with only one magnetic core per particle) and magnetic multi-core nanoparticles (with several magnetic cores per particle). Here, we report multi-core nanoparticle synthesis based on a controlled precipitation process within a well-defined oil in water emulsion to trap the superparamagnetic iron oxide nanoparticles (SPION) in a range of polymer matrices of choice, such as poly(styrene), poly(lactid acid), poly(methyl methacrylate), and poly(caprolactone). Multi-core particles were obtained within the Z-average size range of 130 to 340 nm. With the aim to combine the fast room temperature magnetic relaxation of small individual cores with high magnetization of the ensemble of SPIONs, we used small (<10 nm) core nanoparticles. The performed synthesis is highly flexible with respect to the choice of polymer and SPION loading and gives rise to multi-core particles with interesting magnetic properties and magnetic resonance imaging (MRI) contrast efficacy. PMID:26307966

  19. Synthesis and magnetic properties of gold coated iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Pal, Susmita; Morales, Marienette; Mukherjee, Pritish; Srikanth, Hariharan

    2009-04-01

    We report on synthesis, structural, and magnetic properties of chemically synthesized iron oxide (Fe3O4) and Fe3O4@Au core-shell nanoparticles. Structural characterization was done using x-ray diffraction and transmission electron microscopy, and the magnetite phase of the core (˜6nm) and fcc Au shell (thickness of ˜1nm) were confirmed. Magnetization (M) versus temperature (T) data at H =200Oe for zero-field-cooled and field-cooled modes exhibited a superparamagnetic blocking temperature TB˜35K (40K) for parent (core-shell) system. Enhanced coercivity (Hc˜200Oe) at 5K along with nonsaturating M-H loops observed for Fe3O4@Au nanoparticles indicate the possible role of spin disorder at the Au -Fe3O4 interface and weak exchange coupling between surface and core spins. Analysis of ac susceptibility (χ' and χ″) data shows that the interparticle interaction is reduced upon Au coating and the relaxation mechanism follows the Vogel-Fulcher law.

  20. Lactoferrin conjugated iron oxide nanoparticles for targeting brain glioma cells in magnetic particle imaging

    NASA Astrophysics Data System (ADS)

    Tomitaka, Asahi; Arami, Hamed; Gandhi, Sonu; Krishnan, Kannan M.

    2015-10-01

    Magnetic Particle Imaging (MPI) is a new real-time imaging modality, which promises high tracer mass sensitivity and spatial resolution directly generated from iron oxide nanoparticles. In this study, monodisperse iron oxide nanoparticles with median core diameters ranging from 14 to 26 nm were synthesized and their surface was conjugated with lactoferrin to convert them into brain glioma targeting agents. The conjugation was confirmed with the increase of the hydrodynamic diameters, change of zeta potential, and Bradford assay. Magnetic particle spectrometry (MPS), performed to evaluate the MPI performance of these nanoparticles, showed no change in signal after lactoferrin conjugation to nanoparticles for all core diameters, suggesting that the MPI signal is dominated by Néel relaxation and thus independent of hydrodynamic size difference or presence of coating molecules before and after conjugations. For this range of core sizes (14-26 nm), both MPS signal intensity and spatial resolution improved with increasing core diameter of nanoparticles. The lactoferrin conjugated iron oxide nanoparticles (Lf-IONPs) showed specific cellular internalization into C6 cells with a 5-fold increase in MPS signal compared to IONPs without lactoferrin, both after 24 h incubation. These results suggest that Lf-IONPs can be used as tracers for targeted brain glioma imaging using MPI.

  1. Iron oxide/niobium oxide core-shell magnetic nanoparticle-based phosphopeptide enrichment from biological samples for MALDI MS analysis.

    PubMed

    Lin, Hong-Yi; Chen, Wei-Yu; Chen, Yu-Chie

    2009-04-01

    The feasibility of using niobium oxide-coated magnetic nanoparticles (NPs) as affinity probes for selectively trapping phosphopeptides from peptide mixtures including tryptic digest of caseins, serum, and cell lysate was demonstrated in this study. Phosphopeptide enrichment was rapid when subjecting these systems to microwave heating for 1 min; the probe-target species, which were readily isolated through magnetic separation, were then analyzed using matrix-assisted laser desorption/ ionization mass spectrometry (MALDI MS). Only signals for phosphopeptides were present in the resulting mass spectra. The detection limit for monophosphopeptide was as low as 5 fmol.

  2. Facile One-pot Transformation of Iron Oxides from Fe2O3 Nanoparticles to Nanostructured Fe3O4@C Core-Shell Composites via Combustion Waves

    PubMed Central

    Shin, Jungho; Lee, Kang Yeol; Yeo, Taehan; Choi, Wonjoon

    2016-01-01

    The development of a low-cost, fast, and large-scale process for the synthesis and manipulation of nanostructured metal oxides is essential for incorporating materials with diverse practical applications. Herein, we present a facile one-pot synthesis method using combustion waves that simultaneously achieves fast reduction and direct formation of carbon coating layers on metal oxide nanostructures. Hybrid composites of Fe2O3 nanoparticles and nitrocellulose on the cm scale were fabricated by a wet impregnation process. We demonstrated that self-propagating combustion waves along interfacial boundaries between the surface of the metal oxide and the chemical fuels enabled the release of oxygen from Fe2O3. This accelerated reaction directly transformed Fe2O3 into Fe3O4 nanostructures. The distinctive color change from reddish-brown Fe2O3 to dark-gray Fe3O4 confirmed the transition of oxidation states and the change in the fundamental properties of the material. Furthermore, it simultaneously formed carbon layers of 5–20 nm thickness coating the surfaces of the resulting Fe3O4 nanoparticles, which may aid in maintaining the nanostructures and improving the conductivity of the composites. This newly developed use of combustion waves in hybridized nanostructures may permit the precise manipulation of the chemical compositions of other metal oxide nanostructures, as well as the formation of organic/inorganic hybrid nanostructures. PMID:26902260

  3. Facile One-pot Transformation of Iron Oxides from Fe2O3 Nanoparticles to Nanostructured Fe3O4@C Core-Shell Composites via Combustion Waves

    NASA Astrophysics Data System (ADS)

    Shin, Jungho; Lee, Kang Yeol; Yeo, Taehan; Choi, Wonjoon

    2016-02-01

    The development of a low-cost, fast, and large-scale process for the synthesis and manipulation of nanostructured metal oxides is essential for incorporating materials with diverse practical applications. Herein, we present a facile one-pot synthesis method using combustion waves that simultaneously achieves fast reduction and direct formation of carbon coating layers on metal oxide nanostructures. Hybrid composites of Fe2O3 nanoparticles and nitrocellulose on the cm scale were fabricated by a wet impregnation process. We demonstrated that self-propagating combustion waves along interfacial boundaries between the surface of the metal oxide and the chemical fuels enabled the release of oxygen from Fe2O3. This accelerated reaction directly transformed Fe2O3 into Fe3O4 nanostructures. The distinctive color change from reddish-brown Fe2O3 to dark-gray Fe3O4 confirmed the transition of oxidation states and the change in the fundamental properties of the material. Furthermore, it simultaneously formed carbon layers of 5–20 nm thickness coating the surfaces of the resulting Fe3O4 nanoparticles, which may aid in maintaining the nanostructures and improving the conductivity of the composites. This newly developed use of combustion waves in hybridized nanostructures may permit the precise manipulation of the chemical compositions of other metal oxide nanostructures, as well as the formation of organic/inorganic hybrid nanostructures.

  4. Facile One-pot Transformation of Iron Oxides from Fe2O3 Nanoparticles to Nanostructured Fe3O4@C Core-Shell Composites via Combustion Waves.

    PubMed

    Shin, Jungho; Lee, Kang Yeol; Yeo, Taehan; Choi, Wonjoon

    2016-01-01

    The development of a low-cost, fast, and large-scale process for the synthesis and manipulation of nanostructured metal oxides is essential for incorporating materials with diverse practical applications. Herein, we present a facile one-pot synthesis method using combustion waves that simultaneously achieves fast reduction and direct formation of carbon coating layers on metal oxide nanostructures. Hybrid composites of Fe2O3 nanoparticles and nitrocellulose on the cm scale were fabricated by a wet impregnation process. We demonstrated that self-propagating combustion waves along interfacial boundaries between the surface of the metal oxide and the chemical fuels enabled the release of oxygen from Fe2O3. This accelerated reaction directly transformed Fe2O3 into Fe3O4 nanostructures. The distinctive color change from reddish-brown Fe2O3 to dark-gray Fe3O4 confirmed the transition of oxidation states and the change in the fundamental properties of the material. Furthermore, it simultaneously formed carbon layers of 5-20 nm thickness coating the surfaces of the resulting Fe3O4 nanoparticles, which may aid in maintaining the nanostructures and improving the conductivity of the composites. This newly developed use of combustion waves in hybridized nanostructures may permit the precise manipulation of the chemical compositions of other metal oxide nanostructures, as well as the formation of organic/inorganic hybrid nanostructures.

  5. Washing effect on superparamagnetic iron oxide nanoparticles

    PubMed Central

    Mireles, Laura-Karina; Sacher, Edward; Yahia, L’Hocine; Laurent, Sophie; Stanicki, Dimitri

    2016-01-01

    Much recent research on nanoparticles has occurred in the biomedical area, particularly in the area of superparamagnetic iron oxide nanoparticles (SPIONs); one such area of research is in their use as magnetically directed prodrugs. It has been reported that nanoscale materials exhibit properties different from those of materials in bulk or on a macro scale [1]. Further, an understanding of the batch-to-batch reproducibility and uniformity of the SPION surface is essential to ensure safe biological applications, as noted in the accompanying article [2], because the surface is the first layer that affects the biological response of the human body. Here, we consider a comparison of the surface chemistries of a batch of SPIONs, before and after the supposedly gentle process of dialysis in water. PMID:27141527

  6. Preparation and characterization of thermosensitive PNIPAA-coated iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhang, Shengmao; Zhang, Linna; He, Benfang; Wu, Zhishen

    2008-08-01

    A new and facile approach was established to fabricate thermoresponsive poly(N-isopropylacrylamide) (PNIPAA) coated iron oxide nanoparticles in a non-aqueous medium. The morphology and structure of the nanoparticle-doped composite were analyzed by means of transmission electron microscopy (TEM), x-ray powder diffraction (XRD), and Fourier transformation infrared spectrometry (FTIR). The thermosensitivity of the composite was also investigated. Results indicated that the oil-soluble iron oxide nanoparticles encapsulated with PNIPAA, composed of an inorganic iron oxide core and biocompatible PNIPAA shell, were dispersed well in water and had a sphere-like shape. The PNIPAA-coated iron oxide nanoparticles with such a kind of core-shell structure showed excellent thermosensitivity. Namely, the aqueous suspension of PNIPAA-coated iron oxide nanoparticles dramatically changed from transparent to opaque as the temperature increased from room temperature to 38 °C, showing potential as optical transmittance switch materials and their significance in the fields of protein adsorption and purification controlled release, and drug delivery.

  7. Equilibrium iron isotope fractionation at core-mantle boundary conditions.

    PubMed

    Polyakov, Veniamin B

    2009-02-13

    The equilibrium iron isotope fractionation between lower mantle minerals and metallic iron at core-mantle boundary conditions can be evaluated from the high-pressure 57Fe partial vibrational density of states determined by synchrotron inelastic nuclear resonant x-ray scattering spectroscopy using a diamond anvil. Ferropericlase [(Mg,Fe)O] and (Fe,Mg)SiO3- post-perovskite are enriched in heavy iron isotopes relative to metallic iron at ultrahigh pressures, as opposed to the equilibrium iron isotope fractionation between these compounds at low pressure. The enrichment of Earth and Moon basalts in heavy iron isotopes relative to those from Mars and asteroid Vesta can be explained by the equilibrium iron isotope fractionation during the segregation of Earth's core and the assumption that Earth was already differentiated before the Moon-forming "giant impact." PMID:19213913

  8. Magnetite mineral nanoparticles synthesized naturally in an iron ore deposit

    NASA Astrophysics Data System (ADS)

    Rivas-Sanchez, M. L.; Alva-Valdivia, L. M.

    2013-05-01

    , homogeneous distribution in the colloidal matrix and a superparamagnetic behavior. Increase temperature provoke new magnetite nano-cores and constant growth of the ones already present. The union to magnetite nanoparticles favored the formation of aggregates nano-micrometric strongly compacted with the acquisition of ferromagnetic behavior. The mineralogical-textural characteristic of magnetite nanoparticles and its magnetic properties were an important guide to explain the environmental conditions for iron deposition, suggesting a marine sedimentary exhalative (SEDEX) origin assisted by bacterial.

  9. Oral exposure to polystyrene nanoparticles affects iron absorption

    NASA Astrophysics Data System (ADS)

    Mahler, Gretchen J.; Esch, Mandy B.; Tako, Elad; Southard, Teresa L.; Archer, Shivaun D.; Glahn, Raymond P.; Shuler, Michael L.

    2012-04-01

    The use of engineered nanoparticles in food and pharmaceuticals is expected to increase, but the impact of chronic oral exposure to nanoparticles on human health remains unknown. Here, we show that chronic and acute oral exposure to polystyrene nanoparticles can influence iron uptake and iron transport in an in vitro model of the intestinal epithelium and an in vivo chicken intestinal loop model. Intestinal cells that are exposed to high doses of nanoparticles showed increased iron transport due to nanoparticle disruption of the cell membrane. Chickens acutely exposed to carboxylated particles (50 nm in diameter) had a lower iron absorption than unexposed or chronically exposed birds. Chronic exposure caused remodelling of the intestinal villi, which increased the surface area available for iron absorption. The agreement between the in vitro and in vivo results suggests that our in vitro intestinal epithelium model is potentially useful for toxicology studies.

  10. Characterization of the oleic acid/iron oxide nanoparticle interface by magnetic resonance

    NASA Astrophysics Data System (ADS)

    Masur, S.; Zingsem, B.; Marzi, T.; Meckenstock, R.; Farle, M.

    2016-10-01

    The synthesis of colloidal nanoparticles involves surfactant molecules, which bind to the particle surface and stabilize nanoparticles against aggregation. In many cases these protecting shells also can be used for further functionalization. In this study, we investigated monodisperse single crystalline iron oxide core/shell nanoparticles (FexOy-NPs) in situ covered with an oleic acid layer which showed two electron spin resonance (ESR) signals. The nanoparticles with the ligands attached were characterized by transmission electron microscopy (TEM) and ferro- and paramagnetic resonance (FMR, EPR). Infrared spectroscopy confirmed the presence of the functional groups and revealed that the oleic acid (OA) is chemisorbed as a carboxylate on the iron oxide and is coordinated symmetrically to the oxide atoms. We show that the EPR signal of the OA ligand molecule can be used as a local probe to determine the temperature changes at the surface of the nanoparticle.

  11. Effect of coating thickness of iron oxide nanoparticles on their relaxivity in the MRI

    PubMed Central

    Hajesmaeelzadeh, Farzaneh; Shanehsazzadeh, Saeed; Grüttner, Cordula; Daha, Fariba Johari; Oghabian, Mohammad Ali

    2016-01-01

    Objective(s): Iron oxide nanoparticles have found prevalent applications in various fields including drug delivery, cell separation and as contrast agents. Super paramagnetic iron oxide (SPIO) nanoparticles allow researchers and clinicians to enhance the tissue contrast of an area of interest by increasing the relaxation rate of water. In this study, we evaluate the dependency of hydrodynamic size of iron oxide nanoparticles coated with Polyethylene glycol (PEG) on their relativities with 3 Tesla clinical MRI. Materials and Methods: We used three groups of nanoparticles with nominal sizes 20, 50 and 100 nm with a core size of 8.86 nm, 8.69 nm and 10.4 nm that they were covered with PEG 300 and 600 Da. A clinical magnetic resonance scanner determines the T1 and T2 relaxation times for various concentrations of PEG-coated nanoparticles. Results: The size measurement by photon correlation spectroscopy showed the hydrodynamic sizes of MNPs with nominal 20, 50 and 100 nm with 70, 82 and 116 nm for particles with PEG 600 coating and 74, 93 and 100 nm for particles with PEG 300 coating, respectively. We foud that the relaxivity decreased with increasing overall particle size (via coating thickness). Magnetic resonance imaging showed that by increasing the size of the nanoparticles, r2/r1 increases linearly. Conclusion: According to the data obtained from this study it can be concluded that increments in coating thickness have more influence on relaxivities compared to the changes in core size of magnetic nanoparticles. PMID:27081461

  12. Influence of structure of iron nanoparticles in aggregates on their magnetic properties

    NASA Astrophysics Data System (ADS)

    Rosická, Dana; Šembera, Jan

    2011-09-01

    Zero-valent iron nanoparticles rapidly aggregate. One of the reasons is magnetic forces among the nanoparticles. Magnetic field around particles is caused by composition of the particles. Their core is formed from zero-valent iron, and shell is a layer of magnetite. The magnetic forces contribute to attractive forces among the nanoparticles and that leads to increasing of aggregation of the nanoparticles. This effect is undesirable for decreasing of remediation properties of iron particles and limited transport possibilities. The aggregation of iron nanoparticles was established for consequent processes: Brownian motion, sedimentation, velocity gradient of fluid around particles and electrostatic forces. In our previous work, an introduction of influence of magnetic forces among particles on the aggregation was presented. These forces have significant impact on the rate of aggregation. In this article, a numerical computation of magnetic forces between an aggregate and a nanoparticle and between two aggregates is shown. It is done for random position of nanoparticles in an aggregate and random or arranged directions of magnetic polarizations and for structured aggregates with arranged vectors of polarizations. Statistical computation by Monte Carlo is done, and range of dominant area of magnetic forces around particles is assessed.

  13. Targeted iron oxide nanoparticles for the enhancement of radiation therapy.

    PubMed

    Hauser, Anastasia K; Mitov, Mihail I; Daley, Emily F; McGarry, Ronald C; Anderson, Kimberly W; Hilt, J Zach

    2016-10-01

    To increase the efficacy of radiation, iron oxide nanoparticles can be utilized for their ability to produce reactive oxygen species (ROS). Radiation therapy promotes leakage of electrons from the electron transport chain and leads to an increase in mitochondrial production of the superoxide anion which is converted to hydrogen peroxide by superoxide dismutase. Iron oxide nanoparticles can then catalyze the reaction from hydrogen peroxide to the highly reactive hydroxyl radical. Therefore, the overall aim of this project was to utilize iron oxide nanoparticles conjugated to a cell penetrating peptide, TAT, to escape lysosomal encapsulation after internalization by cancer cells and catalyze hydroxyl radical formation. It was determined that TAT functionalized iron oxide nanoparticles and uncoated iron oxide nanoparticles resulted in permeabilization of the lysosomal membranes. Additionally, mitochondrial integrity was compromised when A549 cells were treated with both TAT-functionalized nanoparticles and radiation. Pre-treatment with TAT-functionalized nanoparticles also significantly increased the ROS generation associated with radiation. A long term viability study showed that TAT-functionalized nanoparticles combined with radiation resulted in a synergistic combination treatment. This is likely due to the TAT-functionalized nanoparticles sensitizing the cells to subsequent radiation therapy, because the nanoparticles alone did not result in significant toxicities. PMID:27521615

  14. Two-component magnetic structure of iron oxide nanoparticles mineralized in Listeria innocua protein cages

    NASA Astrophysics Data System (ADS)

    Usselman, Robert J.; Klem, Michael T.; Russek, Stephen E.; Young, Mark; Douglas, Trevor; Goldfarb, Ron B.

    2010-06-01

    Magnetometry was used to determine the magnetic properties of maghemite (γ-Fe2O3) nanoparticles formed within Listeria innocua protein cage. The electron magnetic resonance spectrum shows the presence of at least two magnetization components. The magnetization curves are explained by a sum of two Langevin functions in which each filled protein cage contains both a large magnetic iron oxide core plus an amorphous surface consisting of small noncoupled iron oxide spin clusters. This model qualitatively explains the observed decrease in the temperature dependent saturation moment and removes an unrealistic temperature dependent increase in the particle moment often observed in nanoparticle magnetization measurements.

  15. Core-size-dependent catalytic properties of bimetallic Au/Ag core-shell nanoparticles.

    PubMed

    Haldar, Krishna Kanta; Kundu, Simanta; Patra, Amitava

    2014-12-24

    Bimetallic core-shell nanoparticles have recently emerged as a new class of functional materials because of their potential applications in catalysis, surface enhanced Raman scattering (SERS) substrate and photonics etc. Here, we have synthesized Au/Ag bimetallic core-shell nanoparticles with varying the core diameter. The red-shifting of the both plasmonic peaks of Ag and Au confirms the core-shell structure of the nanoparticles. Transmission electron microscopy (TEM) analysis, line scan EDS measurement and UV-vis study confirm the formation of core-shell nanoparticles. We have examined the catalytic activity of these core-shell nanostructures in the reaction between 4-nitrophenol (4-NP) and NaBH4 to form 4-aminophenol (4-AP) and the efficiency of the catalytic reaction is found to be increased with increasing the core size of Au/Ag core-shell nanocrystals. The catalytic efficiency varies from 41.8 to 96.5% with varying core size from 10 to 100 nm of Au/Ag core-shell nanoparticles, and the Au100/Ag bimetallic core-shell nanoparticle is found to be 12-fold more active than that of the pure Au nanoparticles with 100 nm diameter. Thus, the catalytic properties of the metal nanoparticles are significantly enhanced because of the Au/Ag core-shell structure, and the rate is dependent on the size of the core of the nanoparticles.

  16. Safety assessment of chronic oral exposure to iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Chamorro, Susana; Gutiérrez, Lucía; Vaquero, María Pilar; Verdoy, Dolores; Salas, Gorka; Luengo, Yurena; Brenes, Agustín; José Teran, Francisco

    2015-05-01

    Iron oxide nanoparticles with engineered physical and biochemical properties are finding a rapidly increasing number of biomedical applications. However, a wide variety of safety concerns, especially those related to oral exposure, still need to be addressed for iron oxide nanoparticles in order to reach clinical practice. Here, we report on the effects of chronic oral exposure to low doses of γ-Fe2O3 nanoparticles in growing chickens. Animal observation, weight, and diet intake reveal no adverse signs, symptoms, or mortality. No nanoparticle accumulation was observed in liver, spleen, and duodenum, with feces as the main excretion route. Liver iron level and duodenal villi morphology reflect the bioavailability of the iron released from the partial transformation of γ-Fe2O3 nanoparticles in the acid gastric environment. Duodenal gene expression studies related to the absorption of iron from γ-Fe2O3 nanoparticles indicate the enhancement of a ferric over ferrous pathway supporting the role of mucins. Our findings reveal that oral administration of iron oxide nanoparticles is a safe route for drug delivery at low nanoparticle doses.

  17. Synthesis and Magneto-Thermal Actuation of Iron Oxide Core–PNIPAM Shell Nanoparticles

    PubMed Central

    2015-01-01

    Superparamagnetic nanoparticles have been proposed for many applications in biotechnology and medicine. In this paper, it is demonstrated how the excellent colloidal stability and magnetic properties of monodisperse and individually densely grafted iron oxide nanoparticles can be used to manipulate reversibly the solubility of nanoparticles with a poly(N-isopropylacrylamide)nitrodopamine shell. “Grafting-to” and “grafting-from” methods for synthesis of an irreversibly anchored brush shell to monodisperse, oleic acid coated iron oxide cores are compared. Thereafter, it is shown that local heating by magnetic fields as well as global thermal heating can be used to efficiently and reversibly aggregate, magnetically extract nanoparticles from solution and spontaneously redisperse them. The coupling of magnetic and thermally responsive properties points to novel uses as smart materials, for example, in integrated devices for molecular separation and extraction. PMID:26270412

  18. A multifunctional core-shell nanoparticle for dendritic cell-based cancer immunotherapy

    NASA Astrophysics Data System (ADS)

    Cho, Nam-Hyuk; Cheong, Taek-Chin; Min, Ji Hyun; Wu, Jun Hua; Lee, Sang Jin; Kim, Daehong; Yang, Jae-Seong; Kim, Sanguk; Kim, Young Keun; Seong, Seung-Yong

    2011-10-01

    Dendritic cell-based cancer immunotherapy requires tumour antigens to be delivered efficiently into dendritic cells and their migration to be monitored in vivo. Nanoparticles have been explored as carriers for antigen delivery, but applications have been limited by the toxicity of the solvents used to make nanoparticles, and by the need to use transfection agents to deliver nanoparticles into cells. Here we show that an iron oxide-zinc oxide core-shell nanoparticle can deliver carcinoembryonic antigen into dendritic cells while simultaneously acting as an imaging agent. The nanoparticle-antigen complex is efficiently taken up by dendritic cells within one hour and can be detected in vitro by confocal microscopy and in vivo by magnetic resonance imaging. Mice immunized with dendritic cells containing the nanoparticle-antigen complex showed enhanced tumour antigen specific T-cell responses, delayed tumour growth and better survival than controls.

  19. Bubble nucleation and migration in a lead–iron hydr(oxide) core–shell nanoparticle

    PubMed Central

    Niu, Kaiyang; Frolov, Timofey; Xin, Huolin L.; Wang, Junling; Asta, Mark; Zheng, Haimei

    2015-01-01

    Iron hydroxide is found in a wide range of contexts ranging from biominerals to steel corrosion, and it can transform to anhydrous oxide via releasing O2 gas and H2O. However, it is not well understood how gases transport through a crystal lattice. Here, we present in situ observation of the nucleation and migration of gas bubbles in iron (hydr)oxide using transmission electron microscopy. We create Pb–FeOOH model core–shell nanoparticles in a liquid cell. Under electron irradiation, iron hydroxide transforms to iron oxide, during which bubbles are generated, and they migrate through the shell to the nanoparticle surface. Geometric phase analysis of the shell lattice shows an inhomogeneous stain field at the bubbles. Our modeling suggests that the elastic interaction between the core and the bubble provides a driving force for bubble migration. PMID:26438864

  20. Mössbauer, magnetization and X-ray diffraction characterization methods for iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Gabbasov, Raul; Polikarpov, Michael; Cherepanov, Valery; Chuev, Michael; Mischenko, Iliya; Lomov, Andrey; Wang, Andrew; Panchenko, Vladislav

    2015-04-01

    Water soluble magnetite iron oxide nanoparticles with oleic polymer coating and average diameters in the range of 5-25 nm, previously determined by TEM, were characterized using Mössbauer, magnetization and X-ray diffraction measurements. Comparative analysis of the results demonstrated a large diversity of magnetic relaxation regimes. Analysis showed the presence of an additional impurity component in the 25 nm nanoparticles, with principally different magnetic nature at the magnetite core. In some cases, X-ray diffraction measurements were unable to estimate the size of the magnetic core and Mössbauer data were necessary for the correct interpretation of the experimental results.

  1. Superparamagnetic iron oxide nanoparticles: magnetic nanoplatforms as drug carriers

    PubMed Central

    Wahajuddin; Arora, Sumit

    2012-01-01

    A targeted drug delivery system is the need of the hour. Guiding magnetic iron oxide nanoparticles with the help of an external magnetic field to its target is the principle behind the development of superparamagnetic iron oxide nanoparticles (SPIONs) as novel drug delivery vehicles. SPIONs are small synthetic γ-Fe2O3 (maghemite) or Fe3O4 (magnetite) particles with a core ranging between 10 nm and 100 nm in diameter. These magnetic particles are coated with certain biocompatible polymers, such as dextran or polyethylene glycol, which provide chemical handles for the conjugation of therapeutic agents and also improve their blood distribution profile. The current research on SPIONs is opening up wide horizons for their use as diagnostic agents in magnetic resonance imaging as well as for drug delivery vehicles. Delivery of anticancer drugs by coupling with functionalized SPIONs to their targeted site is one of the most pursued areas of research in the development of cancer treatment strategies. SPIONs have also demonstrated their efficiency as nonviral gene vectors that facilitate the introduction of plasmids into the nucleus at rates multifold those of routinely available standard technologies. SPION-induced hyperthermia has also been utilized for localized killing of cancerous cells. Despite their potential biomedical application, alteration in gene expression profiles, disturbance in iron homeostasis, oxidative stress, and altered cellular responses are some SPION-related toxicological aspects which require due consideration. This review provides a comprehensive understanding of SPIONs with regard to their method of preparation, their utility as drug delivery vehicles, and some concerns which need to be resolved before they can be moved from bench top to bedside. PMID:22848170

  2. Iron oxide nanoparticles stabilized with dendritic polyglycerols as selective MRI contrast agents

    NASA Astrophysics Data System (ADS)

    Nordmeyer, Daniel; Stumpf, Patrick; Gröger, Dominic; Hofmann, Andreas; Enders, Sven; Riese, Sebastian B.; Dernedde, Jens; Taupitz, Matthias; Rauch, Ursula; Haag, Rainer; Rühl, Eckart; Graf, Christina

    2014-07-01

    Monodisperse small iron oxide nanoparticles functionalized with dendritic polyglycerol (dPG) or dendritic polyglycerol sulfate (dPGS) are prepared. They are highly stable in aqueous solutions as well as physiological media. In particular, oleic acid capped iron oxide particles (core diameter = 11 +/- 1 nm) were modified by a ligand exchange process in a one pot synthesis with dPG and dPGS bearing phosphonate as anchor groups. Dynamic light scattering measurements performed in water and different biological media demonstrate that the hydrodynamic diameter of the particles is only slightly increased by the ligand exchange process resulting in a final diameter of less than 30 nm and that the particles are stable in these media. It is also revealed by magnetic resonance studies that their magnetic relaxivity is reduced by the surface modification but it is still sufficient for high contrast magnetic resonance imaging (MRI). Additionally, incubation of dPGS functionalized iron oxide nanoparticles with human umbilical vein endothelial cells showed a 50% survival at 85 nM (concentration of nanoparticles). Surface plasmon resonance (SPR) studies demonstrate that the dPGS functionalized iron oxide nanoparticles inhibit L-selectin ligand binding whereas the particles containing only dPG do not show this effect. Experiments in a flow chamber with human myelogenous leukemia cells confirmed L-selectin inhibition of the dPGS functionalized iron oxide nanoparticles and with that the L-selectin mediated leukocyte adhesion. These results indicate that dPGS functionalized iron oxide nanoparticles are a promising contrast agent for inflamed tissue probed by MRI.Monodisperse small iron oxide nanoparticles functionalized with dendritic polyglycerol (dPG) or dendritic polyglycerol sulfate (dPGS) are prepared. They are highly stable in aqueous solutions as well as physiological media. In particular, oleic acid capped iron oxide particles (core diameter = 11 +/- 1 nm) were modified by a

  3. Iron oxide nanoparticles: the Influence of synthesis method and size on composition and magnetic properties

    SciTech Connect

    Carvalho, M.D.; Godinho, M.; Cruz, M.M.

    2013-05-01

    Iron oxide nanoparticles with mean diameter ranging from 7 to 20 nm were synthesized using two routes: the precipitation method in controlled atmosphere and a reduction–precipitation method under air, in some cases followed by a hydrothermal treatment. The smallest nanoparticles were obtained by the reduction–precipitation method. In order to establish the composition of the iron oxide nanoparticles and its relation with size, the morphological, structural and magnetic properties of the prepared samples were investigated using X-ray diffraction, transmission electron microscopy, Mössbauer spectroscopy and SQUID magnetometry. The results allow to conclude that the nanoparticles can be essentially described as Fe3–xO₄, x decreasing with the particle size increase. The composition and magnetic behavior of the synthesized iron oxide nanoparticles are directly related with their size. The overall results are compatible with a core@shell structure model, where a magnetite core is surrounded by an oxidized magnetite layer (labeled as maghemite), the magnetite core dimension depending on the average particle size. - Graphical abstract: TEM images and Mössbauer spectroscopy spectra of Fe3–xO₄ samples with different sizes. Highlights: • Fe3–xO₄ nanoparticles with a mean size between 7 and 20 nm were synthesized. • The smallest nanoparticles were obtained by a reduction precipitation method, under air. • The increase of particles size was succeeded using a hydrothermal treatment at 150 °C. • The magnetic properties of the nanoparticles are directly related with their size.

  4. Thermal and electrical conductivity of iron at Earth's core conditions.

    PubMed

    Pozzo, Monica; Davies, Chris; Gubbins, David; Alfè, Dario

    2012-05-17

    The Earth acts as a gigantic heat engine driven by the decay of radiogenic isotopes and slow cooling, which gives rise to plate tectonics, volcanoes and mountain building. Another key product is the geomagnetic field, generated in the liquid iron core by a dynamo running on heat released by cooling and freezing (as the solid inner core grows), and on chemical convection (due to light elements expelled from the liquid on freezing). The power supplied to the geodynamo, measured by the heat flux across the core-mantle boundary (CMB), places constraints on Earth's evolution. Estimates of CMB heat flux depend on properties of iron mixtures under the extreme pressure and temperature conditions in the core, most critically on the thermal and electrical conductivities. These quantities remain poorly known because of inherent experimental and theoretical difficulties. Here we use density functional theory to compute these conductivities in liquid iron mixtures at core conditions from first principles--unlike previous estimates, which relied on extrapolations. The mixtures of iron, oxygen, sulphur and silicon are taken from earlier work and fit the seismologically determined core density and inner-core boundary density jump. We find both conductivities to be two to three times higher than estimates in current use. The changes are so large that core thermal histories and power requirements need to be reassessed. New estimates indicate that the adiabatic heat flux is 15 to 16 terawatts at the CMB, higher than present estimates of CMB heat flux based on mantle convection; the top of the core must be thermally stratified and any convection in the upper core must be driven by chemical convection against the adverse thermal buoyancy or lateral variations in CMB heat flow. Power for the geodynamo is greatly restricted, and future models of mantle evolution will need to incorporate a high CMB heat flux and explain the recent formation of the inner core. PMID:22495307

  5. Thermal and electrical conductivity of iron at Earth's core conditions.

    PubMed

    Pozzo, Monica; Davies, Chris; Gubbins, David; Alfè, Dario

    2012-04-11

    The Earth acts as a gigantic heat engine driven by the decay of radiogenic isotopes and slow cooling, which gives rise to plate tectonics, volcanoes and mountain building. Another key product is the geomagnetic field, generated in the liquid iron core by a dynamo running on heat released by cooling and freezing (as the solid inner core grows), and on chemical convection (due to light elements expelled from the liquid on freezing). The power supplied to the geodynamo, measured by the heat flux across the core-mantle boundary (CMB), places constraints on Earth's evolution. Estimates of CMB heat flux depend on properties of iron mixtures under the extreme pressure and temperature conditions in the core, most critically on the thermal and electrical conductivities. These quantities remain poorly known because of inherent experimental and theoretical difficulties. Here we use density functional theory to compute these conductivities in liquid iron mixtures at core conditions from first principles--unlike previous estimates, which relied on extrapolations. The mixtures of iron, oxygen, sulphur and silicon are taken from earlier work and fit the seismologically determined core density and inner-core boundary density jump. We find both conductivities to be two to three times higher than estimates in current use. The changes are so large that core thermal histories and power requirements need to be reassessed. New estimates indicate that the adiabatic heat flux is 15 to 16 terawatts at the CMB, higher than present estimates of CMB heat flux based on mantle convection; the top of the core must be thermally stratified and any convection in the upper core must be driven by chemical convection against the adverse thermal buoyancy or lateral variations in CMB heat flow. Power for the geodynamo is greatly restricted, and future models of mantle evolution will need to incorporate a high CMB heat flux and explain the recent formation of the inner core.

  6. The biological properties of iron oxide core high-density lipoprotein in experimental atherosclerosis

    PubMed Central

    Skajaa, Torjus; Cormode, David P.; Jarzyna, Peter A.; Delshad, Amanda; Blachford, Courtney; Barazza, Alessandra; Fisher, Edward A.; Gordon, Ronald E.; Fayad, Zahi A.; Mulder, Willem J.M.

    2013-01-01

    Lipoproteins are a family of plasma nanoparticles responsible for the transportation of lipids throughout the body. High-density lipoprotein (HDL), the smallest of the lipoprotein family, measures 7–13 nm in diameter and consists of a cholesteryl ester and triglyceride core that is covered with a monolayer of phospholipids and apolipoproteins. We have developed an iron oxide core HDL nanoparticle (FeO-HDL), which has a lipid based fluorophore incorporated in the phospholipid layer. This nanoparticle provides contrast for optical imaging, magnetic resonance imaging (MRI) and transmission electron microscopy (TEM). Consequently, FeO-HDL can be visualized on the anatomical, cellular and sub-cellular level. In the current study we show that the biophysical features of FeO-HDL closely resemble those of native HDL and that FeO-HDL possess the ability to mimic HDL characteristics both in vitro as well as in vivo. We demonstrate that FeO-HDL can be applied to image HDL interactions and to investigate disease settings where HDL plays a key function. More generally, we have demonstrated a multimodal approach to study the behavior of biomaterials in vitro as well as in vivo. The approach allowed us to study nanoparticle dynamics in circulation, as well as nanoparticle targeting and uptake by tissues and cells of interest. Moreover, we were able to qualitatively assess nanoparticle excretion, critical for translating nanotechnologies to the clinic. PMID:20926130

  7. Iron oxide and gold nanoparticles in cancer therapy

    NASA Astrophysics Data System (ADS)

    Gotman, Irena; Psakhie, Sergey G.; Lozhkomoev, Aleksandr S.; Gutmanas, Elazar Y.

    2016-08-01

    Continuous research activities in the field of nanomedicine in the past decade have, to a great extent, been focused on nanoparticle technologies for cancer therapy. Gold and iron oxide nanoparticles (NP) are two of the most studied inorganic nanomaterials due to their unique optical and magnetic properties. Both types of NPs are emerging as promising systems for anti-tumor drug delivery and for nanoparticle-mediated thermal therapy of cancer. In thermal therapy, localized heating inside tumors or in proximity of tumor cells can be induced, for example, with Au NPs by radiofrequency ablation heating or conversion of photon energy (photothermal therapy) and in iron oxide magnetic NPs by heat generation through relaxation in an alternating magnetic field (magnetic hyperthermia). Furthermore, the superparamagnetic properties of iron oxide nanoparticles have led to their use as potent MRI (magnetic resonance imaging) contrast agents. Surface modification/coating can produce NPs with tailored and desired properties, such as enhanced blood circulation time, stability, biocompatibility and water solubility. To target nanoparticles to specific tumor cells, NPs should be conjugated with targeting moieties on the surface which bind to receptors or other molecular structures on the cell surface. The article presents several approaches to enhancing the specificity of Au and iron oxide nanoparticles for tumor tissue by appropriate surface modification/functionalization, as well as the effect of these treatments on the saturation magnetization value of iron oxide NPs. The use of other nanoparticles and nanostructures in cancer treatment is also briefly reviewed.

  8. In vivo biodistribution of iron oxide nanoparticles: an overview

    NASA Astrophysics Data System (ADS)

    Tate, Jennifer A.; Petryk, Alicia A.; Giustini, Andrew J.; Hoopes, P. Jack

    2011-03-01

    Iron oxide nanoparticles present a promising alternative to conventional energy deposition-based tissue therapies. The success of such nanoparticles as a therapeutic for diseases like cancer, however, depends heavily on the particles' ability to localize to tumor tissue as well as provide minimal toxicity to surrounding tissues and key organs such as those involved in the reticuloendothelial system (RES). We present here the results of a long term clearance study where mice injected intravenously with 2 mg Fe of 100 nm dextran-coated iron oxide nanoparticles were sacrificed at 14 and 580 days post injection. Histological analysis showed accumulation of the nanoparticles in some RES organs by the 14 day time point and clearance of the nanoparticles by the 580 day time point with no obvious toxicity to organs. An additional study reported herein employs 20 nm and 110 nm starch-coated iron oxide nanoparticles at 80 mg Fe/kg mouse in a size/biodistribution study with endpoints at 4, 24 and 72 hours. Preliminary results show nanoparticle accumulation in the liver and spleen with some elevated iron accumulation in tumoral tissues with differences between the 20 nm and the 110 nm nanoparticle depositions.

  9. Pulsed Plasma Synthesis of Iron and Nickel Nanoparticles Coated by Carbon for Medical Applications

    NASA Astrophysics Data System (ADS)

    Abdullaeva, Zhypargul; Omurzak, Emil; Iwamoto, Chihiro; Ihara, Hirotaka; Subban Ganapathy, Hullathy; Sulaimankulova, Saadat; Koinuma, Michio; Mashimo, Tsutomu

    2013-01-01

    Fe and Ni magnetic nanoparticles coated by carbon were synthesized between the Fe-Fe and Ni-Ni metal electrodes, submerged in ethanol using pulsed plasma in a liquid method. Iron coated carbon (Fe@C) nanoparticles have an average size of 32 nm, and Ni@C nanoparticles are 40 nm. Obtained samples exhibit a well-defined crystalline structure of the inner Fe and Ni cores, encapsulated in the graphitic carbon coatings. Cytotoxicity studies performed on the MCF-7 (breast cancer) cell line showed small toxicity about 88-74% at 50 µg/mL of Fe@C and Ni@C nanoparticles, which can be significant criteria for use them in medical cancer treatment. In addition, appropriate sizes, good magnetic properties and well-organized graphitic carbon coatings are highlight merits of Fe@C and Ni@C nanoparticles synthesized by pulsed plasma.

  10. A novel structural Fenton-like nanocatalyst with highly improved catalytic performance for generalized preparation of iron oxide@organic dye polymer core-shell nanospheres.

    PubMed

    Zhao, Guanghui; Peng, Xiaomen; Li, Hongping; Wang, Jianzhi; Zhou, Lincheng; Zhao, Tianqi; Huang, Zhihao; Jiang, Haifei

    2015-05-01

    FexOy@FexOy/C nanoparticles with a soap-bubble-like shell have been synthesized, and the materials exhibit excellent Fenton catalytic performance. More importantly, FexOy@FexOy/C nanoparticles as catalysts and precursors could catalyze organic dye molecules to form iron oxide@organic dye polymer core-shell nanospheres.

  11. A novel structural Fenton-like nanocatalyst with highly improved catalytic performance for generalized preparation of iron oxide@organic dye polymer core-shell nanospheres.

    PubMed

    Zhao, Guanghui; Peng, Xiaomen; Li, Hongping; Wang, Jianzhi; Zhou, Lincheng; Zhao, Tianqi; Huang, Zhihao; Jiang, Haifei

    2015-05-01

    FexOy@FexOy/C nanoparticles with a soap-bubble-like shell have been synthesized, and the materials exhibit excellent Fenton catalytic performance. More importantly, FexOy@FexOy/C nanoparticles as catalysts and precursors could catalyze organic dye molecules to form iron oxide@organic dye polymer core-shell nanospheres. PMID:25828271

  12. Cell Labeling and Targeting with Superparamagnetic Iron Oxide Nanoparticles.

    PubMed

    Tefft, Brandon J; Uthamaraj, Susheil; Harburn, J Jonathan; Klabusay, Martin; Dragomir-Daescu, Dan; Sandhu, Gurpreet S

    2015-10-19

    Targeted delivery of cells and therapeutic agents would benefit a wide range of biomedical applications by concentrating the therapeutic effect at the target site while minimizing deleterious effects to off-target sites. Magnetic cell targeting is an efficient, safe, and straightforward delivery technique. Superparamagnetic iron oxide nanoparticles (SPION) are biodegradable, biocompatible, and can be endocytosed into cells to render them responsive to magnetic fields. The synthesis process involves creating magnetite (Fe3O4) nanoparticles followed by high-speed emulsification to form a poly(lactic-co-glycolic acid) (PLGA) coating. The PLGA-magnetite SPIONs are approximately 120 nm in diameter including the approximately 10 nm diameter magnetite core. When placed in culture medium, SPIONs are naturally endocytosed by cells and stored as small clusters within cytoplasmic endosomes. These particles impart sufficient magnetic mass to the cells to allow for targeting within magnetic fields. Numerous cell sorting and targeting applications are enabled by rendering various cell types responsive to magnetic fields. SPIONs have a variety of other biomedical applications as well including use as a medical imaging contrast agent, targeted drug or gene delivery, diagnostic assays, and generation of local hyperthermia for tumor therapy or tissue soldering.

  13. Magnetic Iron Oxide Nanoparticle Seeded Growth of Nucleotide Coordinated Polymers.

    PubMed

    Liang, Hao; Liu, Biwu; Yuan, Qipeng; Liu, Juewen

    2016-06-22

    The introduction of functional molecules to the surface of magnetic iron oxide nanoparticles (NPs) is of critical importance. Most previously reported methods were focused on surface ligand attachment either by physisorption or covalent conjugation, resulting in limited ligand loading capacity. In this work, we report the seeded growth of a nucleotide coordinated polymer shell, which can be considered as a special form of adsorption by forming a complete shell. Among all of the tested metal ions, Fe(3+) is the most efficient for this seeded growth. A diverse range of guest molecules, including small organic dyes, proteins, DNA, and gold NPs, can be encapsulated in the shell. All of these molecules were loaded at a much higher capacity compared to that on the naked iron oxide NP core, confirming the advantage of the coordination polymer (CP) shell. In addition, the CP shell provides better guest protein stability compared to that of simple physisorption while retaining guest activity as confirmed by the entrapped glucose oxidase assay. Use of this system as a peroxidase nanozyme and glucose biosensor was demonstrated, detecting glucose as low as 1.4 μM with excellent stability. This work describes a new way to functionalize inorganic materials with a biocompatible shell. PMID:27248668

  14. Probing iron at Super-Earth core conditions

    SciTech Connect

    Amadou, N.; Brambrink, E.; Vinci, T.; Benuzzi-Mounaix, A.; Huser, G.; Brygoo, S.; Morard, G.; Guyot, F.; Resseguier, T. de; Mazevet, S.; Miyanishi, K.; Ozaki, N.; Kodama, R.; Henry, O.; Raffestin, D.; Boehly, T.; and others

    2015-02-15

    In this paper, we report on the quasi-isentropic compression of an iron sample using ramp shaped laser irradiation. This technique allows us to quasi-isentropically compress iron up to 700 GPa and 8500 K. To our knowledge, these data are the highest pressures reached on iron in off-Hugoniot conditions and the closest to the thermodynamic states thought to exist in Earth-like planetary cores. The experiment was performed on the Ligne d'Intégration laser facility at CESTA, Bordeaux, France.

  15. Stem cell tracking using iron oxide nanoparticles.

    PubMed

    Bull, Elizabeth; Madani, Seyed Yazdan; Sheth, Roosey; Seifalian, Amelia; Green, Mark; Seifalian, Alexander M

    2014-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) are an exciting advancement in the field of nanotechnology. They expand the possibilities of noninvasive analysis and have many useful properties, making them potential candidates for numerous novel applications. Notably, they have been shown that they can be tracked by magnetic resonance imaging (MRI) and are capable of conjugation with various cell types, including stem cells. In-depth research has been undertaken to establish these benefits, so that a deeper level of understanding of stem cell migratory pathways and differentiation, tumor migration, and improved drug delivery can be achieved. Stem cells have the ability to treat and cure many debilitating diseases with limited side effects, but a main problem that arises is in the noninvasive tracking and analysis of these stem cells. Recently, researchers have acknowledged the use of SPIONs for this purpose and have set out to establish suitable protocols for coating and attachment, so as to bring MRI tracking of SPION-labeled stem cells into common practice. This review paper explains the manner in which SPIONs are produced, conjugated, and tracked using MRI, as well as a discussion on their limitations. A concise summary of recently researched magnetic particle coatings is provided, and the effects of SPIONs on stem cells are evaluated, while animal and human studies investigating the role of SPIONs in stem cell tracking will be explored.

  16. Melting iron at high pressures: Implications for Earth's core

    NASA Astrophysics Data System (ADS)

    Lee, K. K.; Du, Z.

    2013-12-01

    The core, although relatively simple in constitution, is a vast, mostly unknown and virtually untouchable region of Earth. The core comprises about 15% of the Earth's volume and one-third of the mass and is composed of an iron-rich alloy whose precise composition is unknown. Besides composition, the temperature of the Earth's core is fundamental to understanding the thermal structure of the Earth, both at present and in the past. As the inner core boundary is mostly structural--fluid versus solid--the melting curve of iron is critical to pinning down the temperature at this boundary and thus throughout the Earth. Despite several pioneering attempts, the melting temperature of iron at the extreme pressure conditions of the core is highly contentious and either extrapolated from experiments or based on quantum mechanical computations, each of which yield a wide range of results. Using the recently developed two-dimensional, 4-color multi-wavelength imaging radiometric technique coupled with laser flash heating and scanning electron microscopy, we have measured the melting temperature of iron at high pressures. Additionally, preliminary analysis of longer-duration laser heating shows movement within the molten region suggesting low viscosity of the molten metal if Brownian motion is assumed.

  17. Effects of Nanoparticle Size on Cellular Uptake and Liver MRI with PVP-Coated Iron Oxide Nanoparticles

    PubMed Central

    Huang, Jing; Bu, Lihong; Xie, Jin; Chen, Kai; Cheng, Zhen; Li, Xingguo; Chen, Xiaoyuan

    2010-01-01

    The effect of nanoparticle size (30–120 nm) on magnetic resonance imaging (MRI) of hepatic lesions in vivo has been systematically examined using polyvinylpyrrolidone (PVP)-coated iron oxide nanoparticles (PVP-IOs). Such biocompatible PVP-IOs with different sizes were synthesized by a simple one-pot pyrolysis method. These PVP-IOs exhibited good crystallinity and high T2 relaxivities, and the relaxivity increased with the size of the magnetic nanoparticles. It was found that cellular uptake changed with both size and surface physiochemical properties, and that PVP-IO-37 with a core size of 37 nm and hydrodynamic particle size of 100 nm exhibited higher cellular uptake rate and greater distribution than other PVP-IOs and Feridex. We systematically investigated the effect of nanoparticle size on MRI of normal liver and hepatic lesions in vivo. The physical and chemical properties of the nanoparticles influenced their pharmacokinetic behavior, which ultimately determined their ability to accumulate in the liver. The contrast enhancement of PVP-IOs within the liver was highly dependent on the overall size of the nanoparticles, and the 100 nm PVP-IO-37 nanoparticles exhibited the greatest enhancement. These results will have implications in designing engineered nanoparticles that are optimized as MR contrast agents or for use in therapeutics. PMID:21043459

  18. Effects of nanoparticle size on cellular uptake and liver MRI with polyvinylpyrrolidone-coated iron oxide nanoparticles.

    PubMed

    Huang, Jing; Bu, Lihong; Xie, Jin; Chen, Kai; Cheng, Zhen; Li, Xingguo; Chen, Xiaoyuan

    2010-12-28

    The effect of nanoparticle size (30-120 nm) on magnetic resonance imaging (MRI) of hepatic lesions in vivo has been systematically examined using polyvinylpyrrolidone (PVP)-coated iron oxide nanoparticles (PVP-IOs). Such biocompatible PVP-IOs with different sizes were synthesized by a simple one-pot pyrolysis method. These PVP-IOs exhibited good crystallinity and high T(2) relaxivities, and the relaxivity increased with the size of the magnetic nanoparticles. It was found that cellular uptake changed with both size and surface physiochemical properties, and that PVP-IO-37 with a core size of 37 nm and hydrodynamic particle size of 100 nm exhibited higher cellular uptake rate and greater distribution than other PVP-IOs and Feridex. We systematically investigated the effect of nanoparticle size on MRI of normal liver and hepatic lesions in vivo. The physical and chemical properties of the nanoparticles influenced their pharmacokinetic behavior, which ultimately determined their ability to accumulate in the liver. The contrast enhancement of PVP-IOs within the liver was highly dependent on the overall size of the nanoparticles, and the 100 nm PVP-IO-37 nanoparticles exhibited the greatest enhancement. These results will have implications in designing engineered nanoparticles that are optimized as MR contrast agents or for use in therapeutics.

  19. Strength of iron at core pressures and evidence for a weak Earth’s inner core

    SciTech Connect

    Gleason, A. E.; Mao, W. L.

    2013-05-12

    The strength of iron at extreme conditions is crucial information for interpreting geophysical observations of the Earth’s core and understanding how the solid inner core deforms. However, the strength of iron, on which deformation depends, is challenging to measure and accurately predict at high pressure. Here we present shear strength measurements of iron up to pressures experienced in the Earth’s core. Hydrostatic X-ray spectroscopy and non-hydrostatic radial X-ray diffraction measurements of the deviatoric strain in hexagonally close-packed iron uniquely determine its shear strength to pressures above 200 GPa at room temperature. Applying numerical modelling of the rheologic behaviour of iron under pressure, we extrapolate our experimental results to inner-core pressures and temperatures, and find that the bulk shear strength of hexagonally close-packed iron is only ~ 1 GPa at the conditions of the Earth’s centre, 364 GPa and 5,500 K. This suggests that the inner core is rheologically weak, which supports dislocation creep as the dominant creep mechanism influencing deformation.

  20. Iron-carbonate interaction at Earth's core-mantle boundary

    NASA Astrophysics Data System (ADS)

    Dorfman, S. M.; Badro, J.; Nabiei, F.; Prakapenka, V.; Gillet, P.

    2015-12-01

    Carbon storage and flux in the deep Earth are moderated by oxygen fugacity and interactions with iron-bearing phases. The amount of carbon stored in Earth's mantle versus the core depends on carbon-iron chemistry at the core-mantle boundary. Oxidized carbonates subducted from Earth's surface to the lowermost mantle may encounter reduced Fe0 metal from disproportionation of Fe2+ in lower mantle silicates or mixing with the core. To understand the fate of carbonates in the lowermost mantle, we have performed experiments on sandwiches of single-crystal (Ca0.6Mg0.4)CO3 dolomite and Fe foil in the laser-heated diamond anvil cell at lower mantle conditions of 49-110 GPa and 1800-2500 K. Syntheses were conducted with in situ synchrotron X-ray diffraction to identify phase assemblages. After quench to ambient conditions, samples were sectioned with a focused Ga+ ion beam for composition analysis with transmission electron microscopy. At the centers of the heated spots, iron melted and reacted completely with the carbonate to form magnesiowüstite, iron carbide, diamond, magnesium-rich carbonate and calcium carbonate. In samples heated at 49 and 64 GPa, the two carbonates exhibit a eutectoid texture. In the sample heated at 110 GPa, the carbonates form rounded ~150-nm-diameter grains with a higher modal proportion of interspersed diamonds. The presence of reduced iron in the deep lower mantle and core-mantle boundary region will promote the formation of diamonds in carbonate-bearing subducted slabs. The complete reaction of metallic iron to oxides and carbides in the presence of mantle carbonate supports the formation of these phases at the Earth's core-mantle boundary and in ultra-low velocity zones.

  1. Promising iron oxide-based magnetic nanoparticles in biomedical engineering.

    PubMed

    Tran, Phuong Ha-Lien; Tran, Thao Truong-Dinh; Vo, Toi Van; Lee, Beom-Jin

    2012-12-01

    For the past few decades biomedical engineering has imprinted its significant impact on the map of science through its wide applications on many other fields. An important example obviously proving this fact is the versatile application of magnetic nanoparticles in theranostics. Due to preferable properties such as biocompatibility, non-toxicity compared to other metal derivations, iron oxide-based magnetic nanoparticles was chosen to be addressed in this review. Aim of this review is to give the readers a whole working window of these magnetic nanoparticles in the current context of science. Thus, preparation of magnetic iron oxide nanoparticles with the so-far techniques, methods of characterizing the nanoparticles as well as their most recent biomedical applications will be stated.

  2. Core-Shell Composite Nanoparticles: Synthesis, Characterization, and Applications

    NASA Astrophysics Data System (ADS)

    Sanyal, Sriya

    Nanoparticles are ubiquitous in various fields due to their unique properties not seen in similar bulk materials. Among them, core-shell composite nanoparticles are an important class of materials which are attractive for their applications in catalysis, sensing, electromagnetic shielding, drug delivery, and environmental remediation. This dissertation focuses on the study of core-shell type of nanoparticles where a polymer serves as the core and inorganic nanoparticles are the shell. This is an interesting class of supramolecular building blocks and can "exhibit unusual, possibly unique, properties which cannot be obtained simply by co-mixing polymer and inorganic particles". The one-step Pickering emulsion polymerization method was successfully developed and applied to synthesize polystyrene-silica core-shell composite particles. Possible mechanisms of the Pickering emulsion polymerization were also explored. The silica nanoparticles were thermodynamically favorable to self-assemble at liquid-liquid interfaces at the initial stage of polymerization and remained at the interface to finally form the shells of the composite particles. More importantly, Pickering emulsion polymerization was employed to synthesize polystyrene/poly(N-isopropylacrylamide) (PNIPAAm)-silica core-shell nanoparticles with N-isopropylacrylamide incorporated into the core as a co-monomer. The composite nanoparticles were temperature sensitive and could be up-taken by human prostate cancer cells and demonstrated effectiveness in drug delivery and cancer therapy. Similarly, by incorporating poly-2-(N,N)-dimethylamino)ethyl methacrylate (PDMA) into the core, pH sensitive core-shell composite nanoparticles were synthesized and applied as effective carriers to release a rheological modifier upon a pH change. Finally, the research focuses on facile approaches to engineer the transition of the temperature-sensitive particles and develop composite core-shell nanoparticles with a metallic shell.

  3. Melting of Iron Close to the Inner Core Boundary Pressure

    NASA Astrophysics Data System (ADS)

    Kraus, R. G.; Coppari, F.; Fratanduono, D. E.; Eggert, J.; Collins, G. W.

    2014-12-01

    The melting curve of iron at the pressure of the inner core boundary places a strong constraint on the thermal profile within the Earth, the heat flux to the mantle, and also the power to drive the geodynamo. Recent static diamond anvil cell measurements by Anzellini et al. 2013 have accurately measured the melting curve of iron to 200 GPa, which is a tremendous improvement in the available data but is still only 60% of the pressure at the inner core boundary, and thus requires significant extrapolation. Nguyen and Holmes, 2004, have used the sound velocity technique to measure the melting transition on the principal Hugoniot, up to 270 GPa, but some still believe that sound velocity is not an accurate diagnostic of melting as it detects a loss of strength and also that kinetics can mitigate the utility of dynamic melting techniques. Here we use in-situ x-ray diffraction to unambiguously measure the melting transition on the principal Hugoniot of iron to 270 GPa. We also show that iron melts from the hcp phase at pressures up to 270 GPa, which is significantly closer to the inner core boundary than any previous melting curve measurement capable of phase discrimination. From comparison of our measurements to those of Nguyen and Holmes, we show that sound velocity measurements can accurately constrain the melting curve and that the kinetics of melting iron are faster than both laser shock and gas gun experimental timescales. Thereby, dynamic techniques should be trusted for probing the melting curve of metals and they also offer the greatest opportunity to probe the melting curve of iron at the pressure of the inner core boundary and also the higher pressures achieved within the interiors of super-Earths. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  4. Rapid microwave-assisted synthesis of dextran-coated iron oxide nanoparticles for magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Osborne, Elizabeth A.; Atkins, Tonya M.; Gilbert, Dustin A.; Kauzlarich, Susan M.; Liu, Kai; Louie, Angelique Y.

    2012-06-01

    Currently, magnetic iron oxide nanoparticles are the only nanosized magnetic resonance imaging (MRI) contrast agents approved for clinical use, yet commercial manufacturing of these agents has been limited or discontinued. Though there is still widespread demand for these particles both for clinical use and research, they are difficult to obtain commercially, and complicated syntheses make in-house preparation unfeasible for most biological research labs or clinics. To make commercial production viable and increase accessibility of these products, it is crucial to develop simple, rapid and reproducible preparations of biocompatible iron oxide nanoparticles. Here, we report a rapid, straightforward microwave-assisted synthesis of superparamagnetic dextran-coated iron oxide nanoparticles. The nanoparticles were produced in two hydrodynamic sizes with differing core morphologies by varying the synthetic method as either a two-step or single-step process. A striking benefit of these methods is the ability to obtain swift and consistent results without the necessity for air-, pH- or temperature-sensitive techniques; therefore, reaction times and complex manufacturing processes are greatly reduced as compared to conventional synthetic methods. This is a great benefit for cost-effective translation to commercial production. The nanoparticles are found to be superparamagnetic and exhibit properties consistent for use in MRI. In addition, the dextran coating imparts the water solubility and biocompatibility necessary for in vivo utilization.

  5. Magnetic and optical properties of multifunctional core-shell radioluminescence nanoparticles

    PubMed Central

    Chen, Hongyu; Colvin, Daniel C.; Qi, Bin; Moore, Thomas; He, Jian; Mefford, O. Thompson; Alexis, Frank; Gore, John C.; Anker, Jeffrey N.

    2014-01-01

    When X-rays irradiate radioluminescence nanoparticles, they generate visible and near infrared light that can penetrate through centimeters of tissue. X-ray luminescence tomography (XLT) maps the location of these radioluminescent contrast agents at high resolution by scanning a narrow X-ray beam through the tissue sample and collecting the luminescence at every position. Adding magnetic functionality to these radioluminescent particles would enable them to be guided, oriented, and heated using external magnetic fields, while their location and spectrum could be imaged with XLT and complementary magnetic resonance imaging. In this work, multifunctional monodispersed magnetic radioluminescent nanoparticles were developed as potential drug delivery carriers and radioluminescence imaging agents. The particles consisted of a spindle-shaped magnetic γ-Fe2O3 core and a radioluminescent europium-doped gadolinium oxide shell. Particles with solid iron oxide cores displayed saturation magnetizations consistent with their ~13% core volume, however, the iron oxide quenched their luminescence. In order to increase the luminescence, we partially etched the iron oxide core in oxalic acid while preserving the radioluminescent shell. The core size was controlled by the etching time which in turn affected the particles’ luminescence and magnetic properties. Particles with intermediate core sizes displayed both strong magnetophoresis and luminescence properties. They also served as MRI contrast agents with relaxivities of up to 58 mM−1s−1 (r2) and 120 mM−1s−1 (r2*). These particles offer promising multimodal MRI/fluorescence/X-ray luminescence contrast agents. Our core-shell synthesis technique offers a flexible method to control particle size, shape, and composition for a wide range of biological applications of magnetic/luminescent nanoparticles. PMID:24520183

  6. New carboxysilane-coated iron oxide nanoparticles for nonspecific cell labelling.

    PubMed

    Bridot, Jean-Luc; Stanicki, Dimitri; Laurent, Sophie; Boutry, Sébastien; Gossuin, Yves; Leclère, Philippe; Lazzaroni, Roberto; Vander Elst, Luce; Muller, Robert N

    2013-01-01

    Magnetic resonance imaging (MRI) offers the possibility of tracking cells labelled with a contrast agent and evaluating the progress of cell therapies. This requires efficient cell labelling with contrast agents. A basic incubation of cells with iron oxide nanoparticles (NPs) is a common method. This study reports the synthesis at the gram scale of iron oxide nanoparticles as MRI T₂ contrast agents for cell labelling. These NPs are based on small iron oxide cores coated with a thin polysiloxane shell presenting carboxylic acid functions. The iron oxide cores produced have been characterized by transmission electron microscopy, X-ray diffraction, ζ-potential, infrared, photon correlation spectroscopy, atomic force microscopy, magnetometry and relaxometric measurements. These measurements confirmed the expected surface modification by carboxysilane. Carboxylic groups created electrostatic repulsion between NPs when they are deprotonated. Therefore, highly concentrated aqueous solutions of carboxysilane coated iron oxide NPs can be obtained, up to 70% (w/w). These NPs could be used for cell labelling owing to their aggregation and re-dispersion properties. NPs precipitated in Dulbecco's modified Eagle medium induced a rapid association with 3 T6 fibroblast cells and could easily be re-dispersed in phosphate buffer saline solution to obtain properly labelled cells. PMID:24375902

  7. Magnesium and iron nanoparticles production using microorganisms and various salts

    NASA Astrophysics Data System (ADS)

    Kaul, R. K.; Kumar, P.; Burman, U.; Joshi, P.; Agrawal, A.; Raliya, R.; Tarafdar, J. C.

    2012-09-01

    Response of five fungi and two bacteria to different salts of magnesium and iron for production of nanoparticles was studied. Pochonia chlamydosporium, and Aspergillus fumigatus were exposed to three salts of magnesium while Curvularia lunata, Chaetomium globosum, A. fumigatus, A. wentii and the bacteria Alcaligenes faecalis and Bacillus coagulans were exposed to two salts of iron for nanoparticle production. The results revealed that P. chlamydosporium induces development of extracellular nanoparticles in MgCl2 solution while A. fumigatus produces also intracellular nanoparticles when exposed to MgSO4 solution. C. globosum was found as the most effective in producing nanoparticles when exposed to Fe2O3 solution. The FTIR analysis of the nanoparticles obtained from Fe2O3 solution showed the peaks similar to iron (Fe). In general, the species of the tested microbes were selective to different chemicals in their response for synthesis of nanoparticles. Further studies on their characterization and improving the efficiency of promising species of fungi need to be undertaken before tapping their potential as nanonutrients for plants.

  8. Complete Exchange of the Hydrophobic Dispersant Shell on Monodisperse Superparamagnetic Iron Oxide Nanoparticles.

    PubMed

    Bixner, Oliver; Lassenberger, Andrea; Baurecht, Dieter; Reimhult, Erik

    2015-08-25

    High-temperature synthesized monodisperse superparamagnetic iron oxide nanoparticles are obtained with a strongly bound ligand shell of oleic acid and its decomposition products. Most applications require a stable presentation of a defined surface chemistry; therefore, the native shell has to be completely exchanged for dispersants with irreversible affinity to the nanoparticle surface. We evaluate by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) the limitations of commonly used approaches. A mechanism and multiple exchange scheme that attains the goal of complete and irreversible ligand replacement on monodisperse nanoparticles of various sizes is presented. The obtained hydrophobic nanoparticles are ideally suited for magnetically controlled drug delivery and membrane applications and for the investigation of fundamental interfacial properties of ultrasmall core-shell architectures. PMID:26226071

  9. Morphology and electronic structure of the oxide shell on the surface of iron nanoparticles.

    PubMed

    Wang, Chongmin; Baer, Donald R; Amonette, James E; Engelhard, Mark H; Antony, Jiji; Qiang, You

    2009-07-01

    An iron (Fe) nanoparticle exposed to air at room temperature will be instantly covered by an oxide shell that is typically approximately 3 nm thick. The nature of this native oxide shell, in combination with the underlying Fe(0) core, determines the physical and chemical behavior of the core-shell nanoparticle. One of the challenges of characterizing core-shell nanoparticles is determining the structure of the oxide shell, that is, whether it is FeO, Fe(3)O(4), gamma-Fe(2)O(3), alpha-Fe(2)O(3), or something else. The results of prior characterization efforts, which have mostly used X-ray diffraction and spectroscopy, electron diffraction, and transmission electron microscopic imaging, have been framed in terms of one of the known Fe-oxide structures, although it is not necessarily true that the thin layer of Fe oxide is a known Fe oxide. In this Article, we probe the structure of the oxide shell on Fe nanoparticles using electron energy loss spectroscopy (EELS) at the oxygen (O) K-edge with a spatial resolution of several nanometers (i.e., less than that of an individual particle). We studied two types of representative particles: small particles that are fully oxidized (no Fe(0) core) and larger core-shell particles that possess an Fe core. We found that O K-edge spectra collected for the oxide shell in nanoparticles show distinct differences from those of known Fe oxides. Typically, the prepeak of the spectra collected on both the core-shell and the fully oxidized particles is weaker than that collected on standard Fe(3)O(4). Given the fact that the origin of this prepeak corresponds to the transition of the O 1s electron to the unoccupied state of O 2p hybridized with Fe 3d, a weak pre-edge peak indicates a combination of the following four factors: a higher degree of occupancy of the Fe 3d orbital; a longer Fe-O bond length; a decreased covalency of the Fe-O bond; and a measure of cation vacancies. These results suggest that the coordination configuration in

  10. Enhanced Magnetic Properties in Antiferromagnetic-Core/Ferrimagnetic-Shell Nanoparticles

    PubMed Central

    Vasilakaki, Marianna; Trohidou, Kalliopi N.; Nogués, Josep

    2015-01-01

    Bi-magnetic core/shell nanoparticles are gaining increasing interest due to their foreseen applications. Inverse antiferromagnetic(AFM)/ferrimagnetic(FiM) core/shell nanoparticles are particularly appealing since they may overcome some of the limitations of conventional FiM/AFM systems. However, virtually no simulations exist on this type of morphology. Here we present systematic Metropolis Monte Carlo simulations of the exchange bias properties of such nanoparticles. The coercivity, HC, and loop shift, Hex, present a non-monotonic dependence with the core diameter and the shell thickness, in excellent agreement with the available experimental data. Additionally, we demonstrate novel unconventional behavior in FiM/AFM particles. Namely, while HC and Hex decrease upon increasing FiM thickness for small AFM cores (as expected), they show the opposite trend for large cores. This presents a counterintuitive FiM size dependence for large AFM cores that is attributed to the competition between core and shell contributions, which expands over a wider range of core diameters leading to non-vanishing Hex even for very large cores. Moreover, the results also hint different possible ways to enhance the experimental performance of inverse core/shell nanoparticles for diverse applications. PMID:25872473

  11. Synthesis and heating effect of iron/iron oxide composite and iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Zeng, Q.; Baker, I.; Loudis, J. A.; Liao, Y. F.; Hoopes, P. J.

    2007-02-01

    Fe/Fe oxide nanoparticles, in which the core consists of metallic Fe and the shell is composed of Fe oxides, were obtained by reduction of an aqueous solution of FeCl 3 within a NaBH 4 solution, or, using a water-in-oil micro-emulsion with CTAB as the surfactant. The reduction was performed either in an inert atmosphere or in air, and passivation with air was performed to produce the Fe/Fe 3O 4 core/shell composite. Phase identification and particle size were determined by X-ray diffraction and TEM. Thermal analysis was performed using a differential scanning calorimeter. The quasistatic magnetic properties were measured using a VSM, and the specific absorption rates (SARs) of both Fe oxide and Fe/Fe 3O 4 composite nanoparticles either dispersed in methanol or in an epoxy resin were measured by Luxtron fiber temperature sensors in an alternating magnetic field of 150 Oe at 250 kHz. It was found that the preparation conditions, including the concentrations of solutions, the mixing procedure and the heat treatment, influence the particle size, the crystal structure and consequently the magnetic properties of the particles. Compared with Fe oxides, the saturation magnetization (MS) of Fe/Fe 3O 4 particles (100-190 emu/g) can be twice as high, and the coercivity (H C) can be tunable from several Oe to several hundred Oe. Hence, the SAR of Fe/Fe 3O 4 composite nanoparticles can be much higher than that of Fe oxides, with a maximum SAR of 345 W/g. The heating behavior is related to the magnetic behavior of the nanoparticles.

  12. The responses of immune cells to iron oxide nanoparticles.

    PubMed

    Xu, Yaolin; Sherwood, Jennifer A; Lackey, Kimberly H; Qin, Ying; Bao, Yuping

    2016-04-01

    Immune cells play an important role in recognizing and removing foreign objects, such as nanoparticles. Among various parameters, surface coatings of nanoparticles are the first contact with biological system, which critically affect nanoparticle interactions. Here, surface coating effects on nanoparticle cellular uptake, toxicity and ability to trigger immune response were evaluated on a human monocyte cell line using iron oxide nanoparticles. The cells were treated with nanoparticles of three types of coatings (negatively charged polyacrylic acid, positively charged polyethylenimine and neutral polyethylene glycol). The cells were treated at various nanoparticle concentrations (5, 10, 20, 30, 50 μg ml(-1) or 2, 4, 8, 12, 20 μg cm(-2)) with 6 h incubation or treated at a nanoparticle concentration of 50 μg ml(-1) (20 μg cm(-2)) at different incubation times (6, 12, 24, 48 or 72 h). Cell viability over 80% was observed for all nanoparticle treatment experiments, regardless of surface coatings, nanoparticle concentrations and incubation times. The much lower cell viability for cells treated with free ligands (e.g. ~10% for polyethylenimine) suggested that the surface coatings were tightly attached to the nanoparticle surfaces. The immune responses of cells to nanoparticles were evaluated by quantifying the expression of toll-like receptor 2 and tumor necrosis factor-α. The expression of tumor necrosis factor-α and toll-like receptor 2 were not significant in any case of the surface coatings, nanoparticle concentrations and incubation times. These results provide useful information to select nanoparticle surface coatings for biological and biomedical applications. PMID:26817529

  13. Large enhanced dielectric permittivity in polyaniline passivated core-shell nano magnetic iron oxide by plasma polymerization

    SciTech Connect

    Joy, Lija K.; Sooraj, V.; Sethulakshmi, N.; Anantharaman, M. R.; Sajeev, U. S.; Nair, Swapna S.; Narayanan, T. N.; Ajayan, P. M.

    2014-03-24

    Commercial samples of Magnetite with size ranging from 25–30 nm were coated with polyaniline by using radio frequency plasma polymerization to achieve a core shell structure of magnetic nanoparticle (core)–Polyaniline (shell). High resolution transmission electron microscopy images confirm the core shell architecture of polyaniline coated iron oxide. The dielectric properties of the material were studied before and after plasma treatment. The polymer coated magnetite particles exhibited a large dielectric permittivity with respect to uncoated samples. The dielectric behavior was modeled using a Maxwell–Wagner capacitor model. A plausible mechanism for the enhancement of dielectric permittivity is proposed.

  14. Preparation of iron oxide-entrapped chitosan nanoparticles for stem cell labeling.

    PubMed

    Chaleawlert-Umpon, Saowaluk; Mayen, Varissaporn; Manotham, Krissanapong; Pimpha, Nuttaporn

    2010-01-01

    This study intended to prepare iron oxide nanoparticle-entrapped chitosan (CS) nanoparticles for stem cell labeling. The nanoparticles were synthesized by polymerizing iron oxide nanoparticle-associated methacrylic acid monomer in the presence of CS. TEM revealed that the well-defined iron oxide nanoparticles were successfully encapsulated inside the CS nanoparticles. The effect of CS at different [NH(2)]/[COOH] molar ratios on particle size, surface charge, thermal stability and magnetic properties was determined systematically. Internalization and localization of the coated nanoparticles were evaluated by atomic absorption spectrometry and confocal laser scanning microscopy. The Kusa O cell line was chosen as a stem cell model. Interestingly, the uptake of iron oxide-entrapped CS nanoparticles was remarkably enhanced under magnetization and the nanoparticles were mostly located inside cellular compartments. It can be concluded that the iron oxide-entrapped CS nanoparticles have a strong potential for stem cell labeling. PMID:20537238

  15. Synthesis and Stability of Iron Nanoparticles for Lunar Environment Studies

    NASA Technical Reports Server (NTRS)

    Hung, Ching-cheh; McNatt, Jeremiah

    2009-01-01

    Simulant of lunar dust is needed when researching the lunar environment. However, unlike the true lunar dust, today s simulants do not contain nanophase iron. Two different processes have been developed to fabricate nanophase iron to be used as part of the lunar dust simulant: (1) Sequentially treating a mixture of ferric chloride, fluorinated carbon, and soda lime glass beads at about 300 C in nitrogen, at room temperature in air, and then at 1050 C in nitrogen. The product includes glass beads that are grey in color, can be attracted by a magnet, and contain alpha-iron nanoparticles (which seem to slowly lose their lattice structure in ambient air during a period of 12 months). This product may have some similarity to the lunar glassy regolith that contains Fe(sup 0). (2) Heating a mixture of carbon black and a lunar simulant (a mixed metal oxide that includes iron oxide) at 1050 C in nitrogen. This process simulates lunar dust reaction to the carbon in a micrometeorite at the time of impact. The product contains a chemically modified simulant that can be attracted by a magnet and has a surface layer whose iron concentration increased during the reaction. The iron was found to be alpha-iron and Fe3O4 nanoparticles, which appear to grow after the fabrication process, but stabilizes after 6 months of ambient air storage.

  16. Local Structure, Electronic Behavior, and Electrocatalytic Reactivity of CO-Reduced Platinum-Iron Oxide Nanoparticles

    SciTech Connect

    Duchesne, Paul N.; Chen, Guangxu; Zheng, Nanfeng; Zhang, Peng

    2014-02-18

    A series of platinum–iron oxide nanoparticles was synthesized using a “clean” CO-reduction method that employed different ratios of Pt-Fe precursor salts in oleylamine at elevated temperatures. High-resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray spectroscopy (EDS) studies revealed that nearly monodisperse (i.e., with relative standard deviations of less than 15%) nanoparticles with mean diameters of 3.5–4.4 nm and varied elemental compositions (Pt54Fe46 Pt70Fe30, and Pt87Fe13) were obtained. X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) measurements at the Pt L3- and Fe K-edges revealed that these nanoparticles all consisted of a Pt core with amorphous iron oxide on the surface. Furthermore, it was observed that the local structure (e.g., Pt–Pt bond distance and coordination number) and electronic behavior of the Pt–FeO nanoparticles (e.g., Pt d electron density and Fe valence state) are dependent on the Pt-Fe precursor ratios used in their synthesis. Quantum mechanical ab initio calculations were employed to interpret the results from X-ray spectroscopy and help elucidate the relationships between local structure and electronic properties in the nanoparticle samples. Finally, the surface reactivity of these nanoparticles in the oxygen reduction reaction (ORR) was explored, demonstrating higher electrocatalytic activity for all three platinum–iron oxide samples in comparison with a commercial Pt catalyst. The surface reactivity was also found to be sensitive to the Pt-Fe ratios of the nanoparticles and could be correlated with their local structure and electronic behavior.

  17. Effects of Mesoporous Silica Coating and Post-Synthetic Treatment on the Transverse Relaxivity of Iron Oxide Nanoparticles

    PubMed Central

    Hurley, Katie R.; Lin, Yu-Shen; Zhang, Jinjin; Egger, Sam M.; Haynes, Christy L.

    2013-01-01

    Mesoporous silica nanoparticles have the capacity to load and deliver therapeutic cargo and incorporate imaging modalities, making them prominent candidates for theranostic devices. One of the most widespread imaging agents utilized in this and other theranostic platforms is nanoscale superparamagnetic iron oxide. Although several core-shell magnetic mesoporous silica nanoparticles presented in the literature have provided high T2 contrast in vitro and in vivo, there is ambiguity surrounding which parameters lead to enhanced contrast. Additionally, there is a need to understand the behavior of these imaging agents over time in biologically relevant environments. Herein, we present a systematic analysis of how the transverse relaxivity (r2) of magnetic mesoporous silica nanoparticles is influenced by nanoparticle diameter, iron oxide nanoparticle core synthesis, and the use of a hydrothermal treatment. This work demonstrates that samples which did not undergo a hydrothermal treatment experienced a drop in r2 (75% of original r2 within 8 days of water storage), while samples with hydrothermal treatment maintained roughly the same r2 for over 30 days in water. Our results suggest that iron oxide oxidation is the cause of the r2 loss, and this oxidation can be prevented both during synthesis and storage by the use of deoxygenated conditions during nanoparticle synthesis. The hydrothermal treatment also provides colloidal stability, even in acidic and highly salted solutions, and a resistance against acid degradation of the iron oxide nanoparticle core. The results of this study show the promise of multifunctional mesoporous silica nanoparticles but will also likely inspire further investigation into multiples types of theranostic devices, taking into consideration their behavior over time and in relevant biological environments. PMID:23814377

  18. Increasing the Collision Rate of Particle Impact Electroanalysis with Magnetically Guided Pt-Decorated Iron Oxide Nanoparticles.

    PubMed

    Robinson, Donald A; Yoo, Jason J; Castañeda, Alma D; Gu, Brett; Dasari, Radhika; Crooks, Richard M; Stevenson, Keith J

    2015-07-28

    An integrated microfluidic/magnetophoretic methodology was developed for improving signal response time and detection limits for the chronoamperometric observation of discrete nanoparticle/electrode interactions by electrocatalytic amplification. The strategy relied on Pt-decorated iron oxide nanoparticles which exhibit both superparamagnetism and electrocatalytic activity for the oxidation of hydrazine. A wet chemical synthetic approach succeeded in the controlled growth of Pt on the surface of FeO/Fe3O4 core/shell nanocubes, resulting in highly uniform Pt-decorated iron oxide hybrid nanoparticles with good dispersibility in water. The unique mechanism of hybrid nanoparticle formation was investigated by electron microscopy and spectroscopic analysis of isolated nanoparticle intermediates and final products. Discrete hybrid nanoparticle collision events were detected in the presence of hydrazine, an electrochemical indicator probe, using a gold microband electrode integrated into a microfluidic channel. In contrast with related systems, the experimental nanoparticle/electrode collision rate correlates more closely with simple theoretical approximations, primarily due to the accuracy of the nanoparticle tracking analysis method used to quantify nanoparticle concentrations and diffusion coefficients. Further modification of the microfluidic device was made by applying a tightly focused magnetic field to the detection volume to attract the magnetic nanoprobes to the microband working electrode, thereby resulting in a 6-fold increase to the relative frequency of chronoamperometric signals corresponding to discrete nanoparticle impact events.

  19. Removal of hexavalent chromium from aqueous solution by iron nanoparticles*

    PubMed Central

    Niu, Shao-feng; Liu, Yong; Xu, Xin-hua; Lou, Zhang-hua

    2005-01-01

    Groundwater remediation by nanoparticles has received increasing interest in recent years. This report presents a thorough evaluation of hexavalent chromium removal in aqueous solutions using iron (Fe0) nanoparticles. Cr(VI) is a major pollutant of groundwater. Zero-valent iron, an important natural reductant of Cr(VI), is an option in the remediation of contaminated sites, transforming Cr(VI) to essentially nontoxic Cr(III). At a dose of 0.4 g/L, 100% of Cr(VI) (20 mg/L) was degraded. The Cr(VI) removal efficiency decreased significantly with increasing initial pH. Different Fe0 type was compared in the same conditions. The reactivity was in the order starch-stabilized Fe0 nanoparticles>Fe0 nanoparticles>Fe0 powder>Fe0 filings. Electrochemical analysis of the reaction process led to the conclusion that Cr(OH)3 should be the final product of Cr(VI). Iron nanoparticles are good choice for the remediation of heavy metals in groundwater. PMID:16187417

  20. Mercury removal in wastewater by iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Vélez, E.; Campillo, G. E.; Morales, G.; Hincapié, C.; Osorio, J.; Arnache, O.; Uribe, J. I.; Jaramillo, F.

    2016-02-01

    Mercury is one of the persistent pollutants in wastewater; it is becoming a severe environmental and public health problem, this is why nowadays its removal is an obligation. Iron oxide nanoparticles are receiving much attention due to their properties, such as: great biocompatibility, ease of separation, high relation of surface-area to volume, surface modifiability, reusability, excellent magnetic properties and relative low cost. In this experiment, Fe3O4 and γ-Fe2O3 nanoparticles were synthesized using iron salts and NaOH as precipitation agents, and Aloe Vera as stabilizing agent; then these nanoparticles were characterized by three different measurements: first, using a Zetasizer Nano ZS for their size estimation, secondly UV-visible spectroscopy which showed the existence of resonance of plasmon at λmax∼360 nm, and lastly by Scanning Electron Microscopy (SEM) to determine nanoparticles form. The results of this characterization showed that the obtained Iron oxides nanoparticles have a narrow size distribution (∼100nm). Mercury removal of 70% approximately was confirmed by atomic absorption spectroscopy measurements.

  1. Removal of hexavalent chromium from aqueous solution by iron nanoparticles.

    PubMed

    Niu, Shao-Feng; Liu, Yong; Xu, Xin-Hua; Lou, Zhang-Hua

    2005-10-01

    Groundwater remediation by nanoparticles has received increasing interest in recent years. This report presents a thorough evaluation of hexavalent chromium removal in aqueous solutions using iron (Fe(0)) nanoparticles. Cr(VI) is a major pollutant of groundwater. Zero-valent iron, an important natural reductant of Cr(VI), is an option in the remediation of contaminated sites, transforming Cr(VI) to essentially nontoxic Cr(III). At a dose of 0.4 g/L, 100% of Cr(VI) (20 mg/L) was degraded. The Cr(VI) removal efficiency decreased significantly with increasing initial pH. Different Fe(0) type was compared in the same conditions. The reactivity was in the order starch-stabilized Fe(0) nanoparticles>Fe(0) nanoparticles>Fe(0) powder>Fe(0) filings. Electrochemical analysis of the reaction process led to the conclusion that Cr(OH)(3) should be the final product of Cr(VI). Iron nanoparticles are good choice for the remediation of heavy metals in groundwater.

  2. Optimized optical "tractor beam" for core-shell nanoparticles.

    PubMed

    Wang, Neng; Lu, Wanli; Ng, Jack; Lin, Zhifang

    2014-04-15

    It is known that core-shell subwavelength nanoparticles consisting of a dielectric shell and a metallic core can simultaneously support electric and magnetic dipolar resonances, which enhance forward scattering and suppress backward scattering. This creates favorable conditions for optical tractor beam applications. Using the generalized Lorenz-Mie theory and Maxwell stress tensor formulation, we demonstrate how optical pulling forces can be induced and optimized by first-order Bessel beams with appropriate polarization. The transverse stability of the core-shell nanoparticle under ambient damping is also verified by linear stability analysis and dynamical simulation. PMID:24979003

  3. Imaging circulating cells and lymphoid tissues with iron oxide nanoparticles.

    PubMed

    Elias, Andrew; Tsourkas, Andrew

    2009-01-01

    The use of nanometer-sized iron oxide nanoparticles and micron-sized iron oxide particles as magnetic resonance (MR) contrast agents has garnered a high degree of interest in diverse areas of biology and medicine. Applications such as cell tracking, molecular imaging, gene detection, and lymphography are being explored to provide insight into disease mechanisms, monitor therapeutic efficacy, and facilitate diagnostic imaging. What makes iron oxide so appealing is a number of favorable properties including high detectability by MR, biodegradability and low toxicity. Here we describe the recent progress on the use of magnetic nanoparticles in imaging circulating cells and lymphoid tissues. The study of the lymph system and the biodistribution of various circulating immune cells is important in the diagnosis, prognosis, and treatment of a wide range of diseases and is expected to have a profound effect on patient outcome.

  4. Synthesis, structure, and magnetic properties of iron and nickel nanoparticles encapsulated into carbon

    NASA Astrophysics Data System (ADS)

    Tsurin, V. A.; Yermakov, A. Ye.; Uimin, M. A.; Mysik, A. A.; Shchegoleva, N. N.; Gaviko, V. S.; Maikov, V. V.

    2014-02-01

    Nanocomposites based on iron and nickel particles encapsulated into carbon (Fe@C and Ni@C), with an average size of the metal core in the range from 5 to 20 nm and a carbon shell thickness of approximately 2 nm, have been prepared by the gas-phase synthesis method in a mixture of argon and butane. It has been found using X-ray diffraction, transmission electron microscopy, and Mössbauer spectroscopy that iron nanocomposites prepared in butane, apart from the carbon shell, contain the following phases: iron carbide (cementite), α-Fe, and γ-Fe. The phase composition of the Fe@C nanocomposite correlates with the magnetization of approximately 100 emu/g at room temperature. The replacement of butane by methane as a carbon source leads to another state of nanoparticles: no carbon coating is formed, and upon subsequent contact with air, the Fe3O4 oxide shell is formed on the surface of nanoparticles. Nickel-based nanocomposites prepared in butane, apart from pure nickel in the metal core, contain the supersaturated metastable solid solution Ni(C) and carbon coating. The Ni(C) solid solution can decompose both during the synthesis and upon the subsequent annealing. The completeness and degree of decomposition depend on the synthesis regime and the size of nickel nanoparticles: the smaller is the size of nanoparticles, the higher is the degree of decomposition into pure nickel and carbon. The magnetization of the Ni@C nanocomposites is determined by several contributions, for example, the contribution of the magnetic solid solution Ni(C) and the contribution of the nonmagnetic carbon coating; moreover, some contribution to the magnetization can be caused by the superparamagnetic behavior of nanoparticles.

  5. Enhanced magnetic resonance imaging and staining of cancer cells using ferrimagnetic H-ferritin nanoparticles with increasing core size

    PubMed Central

    Cai, Yao; Cao, Changqian; He, Xiaoqing; Yang, Caiyun; Tian, Lanxiang; Zhu, Rixiang; Pan, Yongxin

    2015-01-01

    Purpose This study is to demonstrate the nanoscale size effect of ferrimagnetic H-ferritin (M-HFn) nanoparticles on magnetic properties, relaxivity, enzyme mimetic activities, and application in magnetic resonance imaging (MRI) and immunohistochemical staining of cancer cells. Materials and methods M-HFn nanoparticles with different sizes of magnetite cores in the range of 2.7–5.3 nm were synthesized through loading different amounts of iron into recombinant human H chain ferritin (HFn) shells. Core size, crystallinity, and magnetic properties of those M-HFn nanoparticles were analyzed by transmission electron microscope and low-temperature magnetic measurements. The MDA-MB-231 cancer cells were incubated with synthesized M-HFn nanoparticles for 24 hours in Dulbecco’s Modified Eagle’s Medium. In vitro MRI of cell pellets after M-HFn labeling was performed at 7 T. Iron uptake of cells was analyzed by Prussian blue staining and inductively coupled plasma mass spectrometry. Immunohistochemical staining by using the peroxidase-like activity of M-HFn nanoparticles was carried out on MDA-MB-231 tumor tissue paraffin sections. Results The saturation magnetization (Ms), relaxivity, and peroxidase-like activity of synthesized M-HFn nanoparticles were monotonously increased with the size of ferrimagnetic cores. The M-HFn nanoparticles with the largest core size of 5.3 nm exhibit the strongest saturation magnetization, the highest peroxidase activity in immunohistochemical staining, and the highest r2 of 321 mM−1 s−1, allowing to detect MDA-MB-231 breast cancer cells as low as 104 cells mL−1. Conclusion The magnetic properties, relaxivity, and peroxidase-like activity of M-HFn nanoparticles are size dependent, which indicates that M-HFn nanoparticles with larger magnetite core can significantly enhance performance in MRI and staining of cancer cells. PMID:25878496

  6. Synthesis and characterization of fluorinated magnetic core-shell nanoparticles for inhibition of insulin amyloid fibril formation

    NASA Astrophysics Data System (ADS)

    Skaat, Hadas; Belfort, Georges; Margel, Shlomo

    2009-06-01

    Maghemite (γ-Fe2O3) magnetic nanoparticles of 15.0 ± 2.1 nm are formed by nucleation followed by controlled growth of maghemite thin films on gelatin-iron oxide nuclei. Uniform magnetic γ-Fe2O3/poly (2,2,3,3,4,4,4-heptafluorobutyl acrylate) (γ-Fe2O3/PHFBA) core-shell nanoparticles are prepared by emulsion polymerization of the fluorinated monomer 2,2,3,3,4,4,4-heptafluorobutyl acrylate (HFBA) in the presence of the maghemite nanoparticles. The kinetics of the insulin fibrillation process in the absence and in the presence of the γ-Fe2O3/PHFBA core-shell nanoparticles are elucidated. A significant direct slow transition from α-helix to β-sheets during insulin fibril formation is observed in the presence of the γ-Fe2O3/PHFBA nanoparticles. This is in contradiction to our previous manuscript, which illustrated that the γ-Fe2O3 core nanoparticles do not affect the kinetics of the formation of the insulin fibrils, and to other previous publications that describe acceleration of the fibrillation process by using various types of nanoparticles. These core-shell nanoparticles may therefore be also useful for the inhibition of conformational changes of other amyloidogenic proteins that lead to neurodegenerative diseases such as Alzheimer's, Parkinson's, Huntington's, mad cow and prion diseases.

  7. Preparation of composite with silica-coated nanoparticles of iron oxide spinels for applications based on magnetically induced hyperthermia

    NASA Astrophysics Data System (ADS)

    Andrade, Angela L.; Fabris, José D.; Pereira, Márcio C.; Domingues, Rosana Z.; Ardisson, José D.

    2013-04-01

    It is reported a novel method to prepare magnetic core (iron oxide spinels)-shell (silica) composites containing well-dispersed magnetic nanoparticles in aqueous solution. The synthetic process consists of two steps. In a first step, iron oxide nanoparticles obtained through co-precipitation are dispersed in an aqueous solution containing tetramethylammonium hydroxide; in a second step, particles of this sample are coated with silica, through hydrolyzation of tetraethyl orthosilicate. The intrinsic atomic structure and essential properties of the core-shell system were assessed with powder X-ray diffraction, Fourier transform infrared spectrometry, Mössbauer spectroscopy and transmission electron microscopy. The heat released by this ferrofluid under an AC-generated magnetic field was evaluated by following the temperature evolution under increasing magnetic field strengths. Results strongly indicate that this ferrofluid based on silica-coated iron oxide spinels is technologically a very promising material to be used in medical practices, in oncology.

  8. Magnetic resonance imaging contrast of iron oxide nanoparticles developed for hyperthermia is dominated by iron content

    PubMed Central

    Wabler, Michele; Zhu, Wenlian; Hedayati, Mohammad; Attaluri, Anilchandra; Zhou, Haoming; Mihalic, Jana; Geyh, Alison; DeWeese, Theodore L.; Ivkov, Robert; Artemov, Dmitri

    2015-01-01

    Purpose Magnetic iron oxide nanoparticles (MNPs) are used as contrast agents for magnetic resonance imaging (MRI) and hyperthermia for cancer treatment. The relationship between MRI signal intensity and cellular iron concentration for many new formulations, particularly MNPs having magnetic properties designed for heating in hyperthermia, is lacking. In this study, we examine the correlation between MRI T2 relaxation time and iron content in cancer cells loaded with various MNP formulations. Materials and methods Human prostate carcinoma DU-145 cells were loaded with starch-coated bionised nanoferrite (BNF), iron oxide (Nanomag® D-SPIO), Feridex™, and dextran-coated Johns Hopkins University (JHU) particles at a target concentration of 50 pg Fe/cell using poly-D-lysine transfection reagent. T2-weighted MRI of serial dilutions of these labelled cells was performed at 9.4 T and iron content quantification was performed using inductively coupled plasma mass spectrometry (ICP-MS). Clonogenic assay was used to characterise cytotoxicity. Results No cytotoxicity was observed at twice the target intracellular iron concentration (~100 pg Fe/cell). ICP-MS revealed highest iron uptake efficiency with BNF and JHU particles, followed by Feridex and Nanomag-D-SPIO, respectively. Imaging data showed a linear correlation between increased intracellular iron concentration and decreased T2 times, with no apparent correlation among MNP magnetic properties. Conclusions This study demonstrates that for the range of nanoparticle concentrations internalised by cancer cells the signal intensity of T2-weighted MRI correlates closely with absolute iron concentration associated with the cells. This correlation may benefit applications for cell-based cancer imaging and therapy including nanoparticle-mediated drug delivery and hyperthermia. PMID:24773041

  9. Homogeneous Iron Phosphate Nanoparticles by Combustion of Sprays.

    PubMed

    Rudin, Thomas; Pratsinis, Sotiris E

    2012-06-13

    Low-cost synthesis of iron phosphate nanostructured particles is attractive for large scale fortification of basic foods (rice, bread, etc.) as well as for Li-battery materials. This is achieved here by flame-assisted and flame spray pyrolysis (FASP and FSP) of inexpensive precursors (iron nitrate, phosphate), solvents (ethanol), and support gases (acetylene and methane). The iron phosphate powders produced here were mostly amorphous and exhibited excellent solubility in dilute acid, an indicator of relative iron bioavailability. The amorphous and crystalline fractions of such powders were determined by X-ray diffraction (XRD) and their cumulative size distribution by X-ray disk centrifuge. Fine and coarse size fractions were obtained also by sedimentation and characterized by microscopy and XRD. The coarse size fraction contained maghemite Fe(2)O(3) while the fine was amorphous iron phosphate. Furthermore, the effect of increased production rate (up to 11 g/h) on product morphology and solubility was explored. Using increased methane flow rates through the ignition/pilot flame of the FSP-burner and inexpensive powder precursors resulted in also homogeneous iron phosphate nanoparticles essentially converting the FSP to a FASP process. The powders produced by FSP at increased methane flow had excellent solubility in dilute acid as well. Such use of methane or even natural gas might be economically attractive for large scale flame-synthesis of nanoparticles.

  10. Homogeneous Iron Phosphate Nanoparticles by Combustion of Sprays.

    PubMed

    Rudin, Thomas; Pratsinis, Sotiris E

    2012-06-13

    Low-cost synthesis of iron phosphate nanostructured particles is attractive for large scale fortification of basic foods (rice, bread, etc.) as well as for Li-battery materials. This is achieved here by flame-assisted and flame spray pyrolysis (FASP and FSP) of inexpensive precursors (iron nitrate, phosphate), solvents (ethanol), and support gases (acetylene and methane). The iron phosphate powders produced here were mostly amorphous and exhibited excellent solubility in dilute acid, an indicator of relative iron bioavailability. The amorphous and crystalline fractions of such powders were determined by X-ray diffraction (XRD) and their cumulative size distribution by X-ray disk centrifuge. Fine and coarse size fractions were obtained also by sedimentation and characterized by microscopy and XRD. The coarse size fraction contained maghemite Fe(2)O(3) while the fine was amorphous iron phosphate. Furthermore, the effect of increased production rate (up to 11 g/h) on product morphology and solubility was explored. Using increased methane flow rates through the ignition/pilot flame of the FSP-burner and inexpensive powder precursors resulted in also homogeneous iron phosphate nanoparticles essentially converting the FSP to a FASP process. The powders produced by FSP at increased methane flow had excellent solubility in dilute acid as well. Such use of methane or even natural gas might be economically attractive for large scale flame-synthesis of nanoparticles. PMID:23407874

  11. Development and use of iron oxide nanoparticles (Part 1): Synthesis of iron oxide nanoparticles for MRI

    PubMed Central

    Lodhia, J; Mandarano, G; Ferris, NJ; Eu, P; Cowell, SF

    2010-01-01

    Contrast agents, such as iron oxide, enhance MR images by altering the relaxation times of tissues in which the agent is present. They can also be used to label targeted molecular imaging probes. Unfortunately, no molecular imaging probe is currently available on the clinical MRI market. A promising platform for MRI contrast agent development is nanotechnology, where superparamagnetic iron oxide nanoparticles (SPIONS) are tailored for MR contrast enhancement, and/or for molecular imaging. SPIONs can be produced using a range of methods and the choice of method will be influenced by the characteristics most important for a particular application. In addition, the ability to attach molecular markers to SPIONS heralds their application in molecular imaging. There are many reviews on SPION synthesis for MRI; however, these tend to be targeted to a chemistry audience. The development of MRI contrast agents attracts experienced researchers from many fields including some researchers with little knowledge of medical imaging or MRI. This situation presents medical radiation practitioners with opportunities for involvement, collaboration or leadership in research depending on their level of commitment and their ability to learn. Medical radiation practitioners already possess a large portion of the understanding, knowledge and skills necessary for involvement in MRI development and molecular imaging. Their expertise in imaging technology, patient care and radiation safety provides them with skills that are directly applicable to research on the development and application of SPIONs and MRI. In this paper we argue that MRI SPIONs, currently limited to major research centres, will have widespread clinical use in the future. We believe that knowledge about this growing area of research provides an opportunity for medical radiation practitioners to enhance their specialised expertise to ensure best practice in a truly multi-disciplinary environment. This review outlines how and

  12. Surface-imprinted core-shell nanoparticles for sorbent assays.

    PubMed

    Lu, Chun-Hua; Zhou, Wen-Hui; Han, Bing; Yang, Huang-Hao; Chen, Xi; Wang, Xiao-Ru

    2007-07-15

    In this paper, we present a general protocol for the making of surface-imprinted core-shell nanoparticles via surface reversible addition-fragmentation chain-transfer (RAFT) polymerization using RAFT agent functionalized model silica nanoparticles as the chain-transfer agent. In this protocol, trichloro(4-chloromethylphenyl)silane was immobilized on the surface of SiO2 nanoparticles, forming chloromethylphenyl functionalized silica (silica-Cl). RAFT agent functionalized silica was subsequently produced by substitute reaction of silica-Cl with PhC(S)SMgBr. The grafting copolymerization of 4-vinylpyridine and ethylene glycol dimethacrylate using surface RAFT polymerization and in the presence of 2,4-dichlorophenoxyacetic acid as the template led to the formation of surface-imprinted core-shell nanoparticles. The resulting surface-imprinted core-shell nanoparticles bind the original template 2,4-D with an appreciable selectivity over structurally related compounds. The potential use of the surface-imprinted core-shell nanoparticles as the recognition element in the competitive fluorescent binding assay for 2,4-D was also demonstrated. PMID:17563116

  13. Direct synthesis of magnetite nanoparticles from iron(II) carboxymethylcellulose and their performance as NMR contrast agents

    NASA Astrophysics Data System (ADS)

    da Silva, Delmarcio Gomes; Hiroshi Toma, Sergio; de Melo, Fernando Menegatti; Carvalho, Larissa Vieira C.; Magalhães, Alvicler; Sabadini, Edvaldo; dos Santos, Antônio Domingues; Araki, Koiti; Toma, e. Henrique E.

    2016-01-01

    Iron(II) carboxymethylcellulose (CMC) has been successfully employed in the synthesis of hydrophylic magnetite nanoparticles stabilized with a biopolymer coating, aiming applications in NMR imaging. The new method encompasses a convenient one-step synthetic procedure, allowing a good size control and yielding particles of about 10 nm (core size). In addition to the biocompatibility, the nanoparticles have promoted a drastic reduction in the transverse relaxation time (T2) of the water protons. The relaxivity rates have been investigated as a function of the nanoparticles concentration, showing a better performance in relation to the common NMR contrast agents available in the market.

  14. Facile preparation of surface-exchangeable core@shell iron oxide@gold nanoparticles for magnetic solid-phase extraction: use of gold shell as the intermediate platform for versatile adsorbents with varying self-assembled monolayers.

    PubMed

    Li, Yaping; Qi, Li; Shen, Ying; Ma, Huimin

    2014-02-01

    The core@shell Fe3O4@Au nanoparticles (NPs) functionalized with exchangeable self-assembled monolayers have been developed for mode switching magnetic solid-phase extraction (MSPE) using high performance liquid chromatography with ultraviolet detection. The adsorbents were synthesized by chemical coprecipitation to prepare magnetic cores followed by sonolysis to produce gold shells. Functionalization of Fe3O4@Au NPs surface was realized through self-assembly of commercially available low molecular weight thiol-containing ligands using gold shells as intermediate platform and the dynamic nature of Au-S chemistry allowed substituent of one thiol-containing ligand with another simply by thiol exchange process. The resultant adsorbents were characterized by transmission electronic microscopy, Fourier transform infrared spectroscopy, elemental analysis, contact angle measurement, and vibrating sample magnetometry. To evaluate the versatile performance of the developed MSPE adsorbents, they were applied for normal-phase SPE followed by reversed-phase SPE. A few kinds of diphenols and polycyclic aromatic hydrocarbons (PAHs) were employed as model analytes, respectively. The predominant parameters affecting extraction efficiency were investigated and optimized. Under the optimum experimental conditions, wide dynamic linear range (6.25-1600 μg L(-1) for diphenols and 1.56-100 μg L(-1) for PAHs) with good linearity (r(2)≥0.989) and low detection limits (0.34-16.67 μg L(-1) for diphenols and 0.26-0.52 μg L(-1) for PAHs) were achieved. The advantage of the developed method is that the Fe3O4@Au NPs could be reutilized for preconcentrating diverse target analytes in different SPE modes sequentially simply through treatment with desired thiol-containing ligands.

  15. Synthesis of nanoparticle-cored dendrimers by convergent dendritic functionalization of monolayer-protected nanoparticles.

    PubMed

    Shon, Young-Seok; Choi, Daeock; Dare, Jonathan; Dinh, Tuong

    2008-06-01

    This article presents a synthesis method for nanoparticle-cored dendrimers (NCDs), which have dendritic architectures around a monolayer-protected gold nanoparticle. The synthesis method is based on a strategy in which the synthesis of monolayer-protected nanoparticles is followed by adding dendrons on functionalized nanoparticles by a single coupling reaction. NMR spectroscopy, IR spectroscopy, and thermogravimetric analysis (TGA) characterizations confirmed the successful coupling reaction between dendrons with different generations ([G1], [G2], and [G3]) and COOH-functionalized nanoparticles ( approximately Au201L71). The dendrimer wedge density also could be controlled by reacting nanoparticles having different loading of COOH groups ( approximately 60 and approximately 10% COOH of the 71 ligands per gold nanoparticle) with functionalized dendrons. Transmission electron microscope results showed that this synthesis strategy maintains the average size of the nanoparticle core during dendron coupling reactions. This control over the composition and core size makes the systematic study of NCDs with different generations possible. The chemical stability of NCDs was found to be affected by dendron generation around the nanoparticle core. The current-potential response of NCD films on microelectrode arrays exhibited better electrical conductivity for NCDs with lower dendron generation.

  16. Genotoxicity of Superparamagnetic Iron Oxide Nanoparticles in Granulosa Cells

    PubMed Central

    Pöttler, Marina; Staicu, Andreas; Zaloga, Jan; Unterweger, Harald; Weigel, Bianca; Schreiber, Eveline; Hofmann, Simone; Wiest, Irmi; Jeschke, Udo; Alexiou, Christoph; Janko, Christina

    2015-01-01

    Nanoparticles that are aimed at targeting cancer cells, but sparing healthy tissue provide an attractive platform of implementation for hyperthermia or as carriers of chemotherapeutics. According to the literature, diverse effects of nanoparticles relating to mammalian reproductive tissue are described. To address the impact of nanoparticles on cyto- and genotoxicity concerning the reproductive system, we examined the effect of superparamagnetic iron oxide nanoparticles (SPIONs) on granulosa cells, which are very important for ovarian function and female fertility. Human granulosa cells (HLG-5) were treated with SPIONs, either coated with lauric acid (SEONLA) only, or additionally with a protein corona of bovine serum albumin (BSA; SEONLA-BSA), or with dextran (SEONDEX). Both micronuclei testing and the detection of γH2A.X revealed no genotoxic effects of SEONLA-BSA, SEONDEX or SEONLA. Thus, it was demonstrated that different coatings of SPIONs improve biocompatibility, especially in terms of genotoxicity towards cells of the reproductive system. PMID:26540051

  17. Iron oxide nanoparticles in different modifications for antimicrobial phototherapy

    NASA Astrophysics Data System (ADS)

    Tuchina, Elena S.; Kozina, Kristina V.; Shelest, Nikita A.; Kochubey, Vyacheslav I.; Tuchin, Valery V.

    2014-03-01

    The main goal of this study was to investigate the sensitivity of microorganisms to combined action of blue light and iron oxide nanoparticles. Two strains of Staphylococcus aureus - methicillin-sensitive and meticillin-resistant were used. As a blue light source LED with spectral maximum at 405 nm was taken. The light exposure was ranged from 5 to 30 min. The Fe2O3 (diameter ˜27 nm), Fe3O4 nanoparticles (diameter ˜19 nm), and composite Fe2O3/TiO2 nanoparticles (diameter ˜100 nm) were synthesized. It was shown that irradiation by blue light caused from 20% to 88% decrease in the number of microorganisms treated with nanoparticles. Morphological changes in bacterial cells after phototreatment were analyzed using scanning electron microscope.

  18. Process to make core-shell structured nanoparticles

    DOEpatents

    Luhrs, Claudia; Phillips, Jonathan; Richard, Monique N

    2014-01-07

    Disclosed is a process for making a composite material that contains core-shell structured nanoparticles. The process includes providing a precursor in the form of a powder a liquid and/or a vapor of a liquid that contains a core material and a shell material, and suspending the precursor in an aerosol gas to produce an aerosol containing the precursor. In addition, the process includes providing a plasma that has a hot zone and passing the aerosol through the hot zone of the plasma. As the aerosol passes through the hot zone of the plasma, at least part of the core material and at least part of the shell material in the aerosol is vaporized. Vapor that contains the core material and the shell material that has been vaporized is removed from the hot zone of the plasma and allowed to condense into core-shell structured nanoparticles.

  19. Magnetic Iron Oxide Nanoparticles: Synthesis and Surface Functionalization Strategies

    NASA Astrophysics Data System (ADS)

    Wu, Wei; He, Quanguo; Jiang, Changzhong

    2008-10-01

    Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation, structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application briefly. In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered. Finally, some future trends and prospective in these research areas are also discussed.

  20. Magnetic Iron Oxide Nanoparticles: Synthesis and Surface Functionalization Strategies

    PubMed Central

    2008-01-01

    Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation, structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application briefly. In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered. Finally, some future trends and prospective in these research areas are also discussed. PMID:21749733

  1. Characterization and reactivity of iron nanoparticles prepared with added Cu, Pd, and Ni.

    PubMed

    Chun, Chan Lan; Baer, Donald R; Matson, Dean W; Amonette, James E; Penn, R Lee

    2010-07-01

    The association of a secondary metal with iron particles affects redox reactivity in engineered remediation systems. However, the structural characteristics of the metal additives and mechanism responsible for changes in reactivity have not been fully elucidated. Here, we synthesized iron nanoparticles with Cu, Pd, and Ni content ranging from 0-2 mol % via a solution deposition process (SDP), hydrogen reduction process (HRP), or hydrogen reduction of ferrihydrite coprecipitated with the metal cations (HRCO). Results from solid-state characterization show that the synthesis methods produced similar iron core/magnetite shell particles but produced substantial differences in terms of the distribution of the metal additives. In SDP, the metal additives were heterogeneously distributed on the surface of the particles. The metal additives were clearly discernible in TEM images as spherical nanoparticles (5-20 nm) on the HRP and HRCO particles. Because the metals were integral to the synthesis process, we hypothesize that the metal additive is present as solute within the iron core of the HRCO particles. Kinetic batch experiments of carbon tetrachloride (CT) degradation were performed to quantitatively compare the redox reactivity of the particles. Overall, metal additives resulted in enhanced pseudo-first-order rate constants of CT degradation (k(O,CT)) compared to that of the iron nanoparticles. For the bimetallic iron nanoparticles prepared by SDP and HRP, k(O,CT) increased with the concentration of metal additives. The values of chloroform yield (Y(CF)) were independent of the identity and amount of metal additives. However, both k(O,CT) and Y(CF) of the HRCO iron particles were significantly increased. Results suggest that it is the distribution of the metal additives that most strongly impacts reactivity and product distribution. For example, for materials with ca. 0.9 mol % Ni, reactivity and Y(CF) varied substantially (HRCO > SDP > HRP), and HRCO-NiFe resulted in

  2. Characterization and Reactivity of Iron Nanoparticles Prepared with Added Cu, Pd, and Ni

    SciTech Connect

    Chun, Chan Lan; Baer, Donald R.; Matson, Dean W.; Amonette, James E.; Penn, Ryland L.

    2010-07-01

    The presence of a secondary metal on iron particles affects redox reactivity in engineered remediation systems. However, the structural characteristics of the metal additives and mechanism responsible for changes in reactivity have not been fully elucidated. Here, we synthesized iron nanoparticles with Cu, Pd, and Ni content ranging from 0-2 mol% via a solution deposition process (SDP), hydrogen reduction process (HRP), or hydrogen reduction of ferrihydrite coprecipitated with the metal cations (HRCO). Results from solid-state characterization show that the synthetic methods produced similar iron core/magnetite shell particles but produced substantial differences in terms of the distribution of the metal additive. In SDP, the metal additives were heterogeneous distributed on the surface of the particles. The metal additives were clearly discernable in TEM images as spherical nanoparticles (2-4 nm) on the HRP and HRCO particles. In addition, we hypothesize that the metal additive is also present as solute within the iron core of the HRCO particles. Kinetic batch experiments of carbon tetrachloride (CT) degradation were performed to quantitatively compare the redox reactivity of the particles. Overall, metal additives resulted in enhanced overall pseudo-first order rate constants of CT degradation (kO,CT) compared to that of the iron nanoparticles. For the bimetallic iron nanoparticles prepared by SDP and HRP, kO,CT increased with the concentration of metal additives. The values of chloroform yield (YCF) were independent of the identity and amount of metal additives. However, both kO,CT and YCF of the HRCO iron particles were significantly greater. Results suggest that it is the distribution of the metal additives that most strongly impacts reactivity and product distribution. For example, for materials with ca. 0.9 50 mol% Ni, reactivity and YCF varied substantially (HRCO>SDP>HRP), and HRCO-NiFe resulted in the lowest final chloroform concentration because the

  3. Synthesis of amorphous carbon nanofibers using iron nanoparticles as catalysts

    NASA Astrophysics Data System (ADS)

    Ali, Mokhtar; Ramana, G. Venkata; Padya, Balaji; Srikanth, V. V. S. S.; Jain, P. K.

    2013-06-01

    Amongst various carbon nanomaterials, carbon nanofibers (CNFs) have lately attracted considerable interest as a promising reinforcement in polymer matrix composites. CNFs are often synthesized using copper nanoparticles as catalysts and by using chemical vapor deposition (CVD). In this work iron (Fe) nanoparticles are used as catalysts to synthesize amorphous carbon nanofibers. This owes significance since Fe nanoparticles often lead to tubes rather than fibers. Fe nanoparticles (size ˜30-60nm) are prepared by first mixing an appropriate quantity of potassium sodium tartrate tetrahydrate salt with iron (II) chloride dehydrate to obtain iron tartrate and then dried and heated in vacuum oven at about 250°C to remove tartrate. In a subsequent step, CNFs are obtained by using CVD. Acetylene was used as the carbon source in the CVD process. Scanning and transmission electron microscopy show the formation of nanofibers whose diameter is dependent on the size of Fe catalysts. Raman scattering from the fibers show that they are made up of carbon and are amorphous.

  4. Size-dependent magnetic properties of iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Patsula, Vitalii; Moskvin, Maksym; Dutz, Silvio; Horák, Daniel

    2016-01-01

    Uniform iron oxide nanoparticles in the size range from 10 to 24 nm and polydisperse 14 nm iron oxide particles were prepared by thermal decomposition of Fe(III) carboxylates in the presence of oleic acid and co-precipitation of Fe(II) and Fe(III) chlorides by ammonium hydroxide followed by oxidation, respectively. While the first method produced hydrophobic oleic acid coated particles, the second one formed hydrophilic, but uncoated, nanoparticles. To make the iron oxide particles water dispersible and colloidally stable, their surface was modified with poly(ethylene glycol) and sucrose, respectively. Size and size distribution of the nanoparticles was determined by transmission electron microscopy, dynamic light scattering and X-ray diffraction. Surface of the PEG-functionalized and sucrose-modified iron oxide particles was characterized by Fourier transform infrared (FT-IR) and Raman spectroscopy and thermogravimetric analysis (TGA). Magnetic properties were measured by means of vibration sample magnetometry and specific absorption rate in alternating magnetic fields was determined calorimetrically. It was found, that larger ferrimagnetic particles showed higher heating performance than smaller superparamagnetic ones. In the transition range between superparamagnetism and ferrimagnetism, samples with a broader size distribution provided higher heating power than narrow size distributed particles of comparable mean size. Here presented particles showed promising properties for a possible application in magnetic hyperthermia.

  5. Impact of core dielectric properties on the localized surface plasmonic spectra of gold-coated magnetic core-shell nanoparticles.

    PubMed

    Chaffin, Elise Anne; Bhana, Saheel; O'Connor, Ryan Timothy; Huang, Xiaohua; Wang, Yongmei

    2014-12-11

    Gold-coated iron oxide core-shell nanoparticles (IO-Au NPs) are of interest for use in numerous biomedical applications because of their unique combined magnetic-plasmonic properties. Although the effects of the core-dielectric constant on the localized surface plasmon resonance (LSPR) peak position of Au-shell particles have been previously investigated, the impact that light-absorbing core materials with complex dielectric functions have on the LSPR peak is not well established. In this study, we use extended Mie theory for multilayer particles to examine the individual effects of the real and imaginary components of core refractive indices on Au-shell NP plasmonic peaks. We find that the imaginary component dampens the intensity of the cavity plasmon and results in a decrease of surface plasmon coupling. For core materials with large imaginary refractive indices, the coupled mode LSPR peak disappears, and only the anticoupled mode remains. Our findings show that the addition of a nonabsorbing polymer layer to the core surface decreases the dampening of the cavity plasmon and increases LSPR spectral intensity. Additionally, we address apparent discrepancies in the literature regarding the effects of Au-shell thickness on LSPR peak shifts.

  6. The end of the iron-core age.

    NASA Technical Reports Server (NTRS)

    Lyttleton, R. A.

    1973-01-01

    The terrestrial planets aggregated essentially from small particles, to begin as solid cool bodies with the same general compositions, and there is no possibility of an iron-core developing within any of them at any stage. Their differing internal and surface properties receive ready explanation from their different masses which determine whether the pressures within are sufficient to bring about phase-changes. The claim that the terrestrial core can be identified by means of shock-wave data as nickel-iron is based on theoretical misconception, whereas the actual seismic data establish an uncompressed-density value much lower than any such mixture could have. The onset of the Ramsey phase-change in the earth takes the form of a rapid initial collapse to produce a large core in metallic state which thereafter continues to grow secularly as a result of radioactive heating and leads to reduction of surface-area at long last adequate to account for folded and thrusted mountain-building.

  7. The role of iron redox state in the genotoxicity of ultrafine superparamagnetic iron oxide nanoparticles.

    PubMed

    Singh, Neenu; Jenkins, Gareth J S; Nelson, Bryant C; Marquis, Bryce J; Maffeis, Thierry G G; Brown, Andy P; Williams, Paul M; Wright, Chris J; Doak, Shareen H

    2012-01-01

    Ultrafine superparamagnetic iron oxide nanoparticles (USPION) hold great potential for revolutionising biomedical applications such as MRI, localised hyperthermia, and targeted drug delivery. Though evidence is increasing regarding the influence of nanoparticle physico-chemical features on toxicity, data however, is lacking that assesses a range of such characteristics in parallel. We show that iron redox state, a subtle though important physico-chemical feature of USPION, dramatically modifies the cellular uptake of these nanoparticles and influences their induction of DNA damage. Surface chemistry was also found to have an impact and evidence to support a potential mechanism of oxidative DNA damage behind the observed responses has been demonstrated. As human exposure to ferrofluids is predicted to increase through nanomedicine based therapeutics, these findings are important in guiding the fabrication of USPION to ensure they have characteristics that support biocompatibility. PMID:22027595

  8. Development of Iron Doped Silicon Nanoparticles as Bimodal Imaging Agents

    PubMed Central

    Singh, Mani P.; Atkins, Tonya M.; Muthuswamy, Elayaraja; Kamali, Saeed; Tu, Chuqiao; Louie, Angelique Y.; Kauzlarich, Susan M.

    2012-01-01

    We demonstrate the synthesis of water-soluble allylamine terminated Fe doped Si (SixFe) nanoparticles as bimodal agents for optical and magnetic imaging. The preparation involves the synthesis of a single source iron containing precursor, Na4Si4 with x% Fe (x = 1, 5, 10), and its subsequent reaction with NH4Br to produce hydrogen terminated SixFe nanoparticles. The hydrogen-capped nanoparticles are further terminated with allylamine via thermal hydrosilylation. Transmission electron microscopy (TEM) indicates that the average particle diameter is ~3.0±1.0 nm. The Si5Fe nanoparticles show strong photoluminescence quantum yield in water (~ 10 %) with significant T2 contrast (r2/r1value of 4.31). Electron paramagnetic resonance (EPR) and Mössbauer spectroscopies indicate that iron in the nanoparticles is in the +3 oxidation state. Analysis of cytotoxicity using the resazurin assay on HepG2 liver cells indicates that the particles have minimal toxicity. PMID:22616623

  9. Measurements of Electrical and Thermal Conductivity of Iron Under Earth's Core Conditions

    NASA Astrophysics Data System (ADS)

    Ohta, K.; Kuwayama, Y.; Shimizu, K.; Yagi, T.; Hirose, K.; Ohishi, Y.

    2014-12-01

    Secular cooling of the Earth's core induces the convection of the conductive liquid outer core, which generates the geomagnetic field, and the growth of the solid inner core. Since iron is the primary component of the Earth's core, the electrical and thermal conductivity of iron in both solid and liquid states are key pieces of information for estimating the transport properties of the core. We performed electrical and thermal conductivity measurements on iron under core conditions in a laser-heated diamond anvil cell. Our electrical conductivity measurements on iron clearly show resistivity saturation phenomena in iron under high pressure and high temperature conditions as predicted in a recent laboratory-based model for the core conductivity (Gomi et al., 2013). Direct measurements of thermal diffusivity of iron have been also preformed at high pressures by using the pulsed light heating thermoreflectance technique, which enable us to confirm the validity of the Wiedemann-Franz law toward transition metal under high pressure.

  10. Single-step gas phase synthesis of stable iron aluminide nanoparticles with soft magnetic properties

    SciTech Connect

    Vernieres, Jerome Benelmekki, Maria; Kim, Jeong-Hwan; Grammatikopoulos, Panagiotis; Diaz, Rosa E.; Bobo, Jean-François; Sowwan, Mukhles

    2014-11-01

    Soft magnetic alloys at the nanoscale level have long generated a vivid interest as candidate materials for technological and biomedical purposes. Consequently, controlling the structure of bimetallic nanoparticles in order to optimize their magnetic properties, such as high magnetization and low coercivity, can significantly boost their potential for related applications. However, traditional synthesis methods stumble upon the long standing challenge of developing true nanoalloys with effective control over morphology and stability against oxidation. Herein, we report on a single-step approach to the gas phase synthesis of soft magnetic bimetallic iron aluminide nanoparticles, using a versatile co-sputter inert gas condensation technique. This method allowed for precise morphological control of the particles; they consisted of an alloy iron aluminide crystalline core (DO{sub 3} phase) and an alumina shell, which reduced inter-particle interactions and also prevented further oxidation and segregation of the bimetallic core. Remarkably, the as-deposited alloy nanoparticles show interesting soft magnetic properties, in that they combine a high saturation magnetization (170 emu/g) and low coercivity (less than 20 Oe) at room temperature. Additional functionality is tenable by modifying the surface of the particles with a polymer, to ensure their good colloidal dispersion in aqueous environments.

  11. Single-step gas phase synthesis of stable iron aluminide nanoparticles with soft magnetic properties

    NASA Astrophysics Data System (ADS)

    Vernieres, Jerome; Benelmekki, Maria; Kim, Jeong-Hwan; Grammatikopoulos, Panagiotis; Bobo, Jean-François; Diaz, Rosa E.; Sowwan, Mukhles

    2014-11-01

    Soft magnetic alloys at the nanoscale level have long generated a vivid interest as candidate materials for technological and biomedical purposes. Consequently, controlling the structure of bimetallic nanoparticles in order to optimize their magnetic properties, such as high magnetization and low coercivity, can significantly boost their potential for related applications. However, traditional synthesis methods stumble upon the long standing challenge of developing true nanoalloys with effective control over morphology and stability against oxidation. Herein, we report on a single-step approach to the gas phase synthesis of soft magnetic bimetallic iron aluminide nanoparticles, using a versatile co-sputter inert gas condensation technique. This method allowed for precise morphological control of the particles; they consisted of an alloy iron aluminide crystalline core (DO3 phase) and an alumina shell, which reduced inter-particle interactions and also prevented further oxidation and segregation of the bimetallic core. Remarkably, the as-deposited alloy nanoparticles show interesting soft magnetic properties, in that they combine a high saturation magnetization (170 emu/g) and low coercivity (less than 20 Oe) at room temperature. Additional functionality is tenable by modifying the surface of the particles with a polymer, to ensure their good colloidal dispersion in aqueous environments.

  12. Superparamagnetic iron oxide nanoparticles stabilized by a poly(amidoamine)-rhenium complex as potential theranostic probe.

    PubMed

    Maggioni, Daniela; Arosio, Paolo; Orsini, Francesco; Ferretti, Anna M; Orlando, Tomas; Manfredi, Amedea; Ranucci, Elisabetta; Ferruti, Paolo; D'Alfonso, Giuseppe; Lascialfari, Alessandro

    2014-01-21

    Three-component nanocomposites, constituted by a superparamagnetic iron oxide core coated with a polymeric surfactant bearing tightly bound Re(CO)3 moieties, were prepared and fully characterized. The water soluble and biocompatible surfactant was a linear poly(amidoamine) copolymer (PAA), containing cysteamine pendants in the minority part (ISA23SH), able to coordinate Re(CO)3 fragments. For the synthesis of the nanocomposites two methods were compared, involving either (i) peptization of bare magnetite nanoparticles by interaction with the preformed ISA23SH-Re(CO)3 complex, or (ii) "one-pot" synthesis of iron oxide nanoparticles in the presence of the ISA23SH copolymer, followed by complexation of Re to the SPIO@ISA23SH nanocomposite. Full characterization by TEM, DLS, TGA, SQUID, and relaxometry showed that the second method gave better results. The magnetic cores had a roundish shape, with low dispersion (mean diameter ca. 6 nm) and a tendency to form larger aggregates (detected both by TEM and DLS), arising from multiple interactions of the polymeric coils. Aggregation did not affect the stability of the nano-suspension, found to be stable for many months without precipitate formation. The SPIO@PAA-Re nanoparticles (NPs) showed superparamagnetic behaviour and nuclear relaxivities similar or superior to commercial MRI contrast agents (CAs), which make them promising as MRI "negative" CAs. The possibility to encapsulate (186/188)Re isotopes (γ and β emitters) gives these novel NPs the potential to behave as bimodal nanostructures devoted to theranostic applications.

  13. Multifunctional Iron Oxide Nanoparticles for Diagnostics, Therapy and Macromolecule Delivery

    PubMed Central

    Yen, Swee Kuan; Padmanabhan, Parasuraman; Selvan, Subramanian Tamil

    2013-01-01

    In recent years, multifunctional nanoparticles (NPs) consisting of either metal (e.g. Au), or magnetic NP (e.g. iron oxide) with other fluorescent components such as quantum dots (QDs) or organic dyes have been emerging as versatile candidate systems for cancer diagnosis, therapy, and macromolecule delivery such as micro ribonucleic acid (microRNA). This review intends to highlight the recent advances in the synthesis and application of multifunctional NPs (mainly iron oxide) in theranostics, an area used to combine therapeutics and diagnostics. The recent applications of NPs in miRNA delivery are also reviewed. PMID:24396508

  14. Soft template strategy to synthesize iron oxide-titania yolk-shell nanoparticles as high-performance anode materials for lithium-ion battery applications.

    PubMed

    Lim, Joohyun; Um, Ji Hyun; Ahn, Jihoon; Yu, Seung-Ho; Sung, Yung-Eun; Lee, Jin-Kyu

    2015-05-18

    Yolk-shell-structured nanoparticles with iron oxide core, void, and a titania shell configuration are prepared by a simple soft template method and used as the anode material for lithium ion batteries. The iron oxide-titania yolk-shell nanoparticles (IO@void@TNPs) exhibit a higher and more stable capacity than simply mixed nanoparticles of iron oxide and hollow titania because of the unique structure obtained by the perfect separation between iron oxide nanoparticles, in combination with the adequate internal void space provided by stable titania shells. Moreover, the structural effect of IO@void@TNPs clearly demonstrates that the capacity retention value after 50 cycles is approximately 4 times that for IONPs under harsh operating conditions, that is, when the temperature is increased to 80 °C.

  15. Nanodisco Balls: Control over Surface versus Core Loading of Diagnostically Active Nanocrystals into Polymer Nanoparticles

    PubMed Central

    2015-01-01

    Nanoparticles of complex architectures can have unique properties. Self-assembly of spherical nanocrystals is a high yielding route to such systems. In this study, we report the self-assembly of a polymer and nanocrystals into aggregates, where the location of the nanocrystals can be controlled to be either at the surface or in the core. These nanospheres, when surface decorated with nanocrystals, resemble disco balls, thus the term nanodisco balls. We studied the mechanism of this surface loading phenomenon and found it to be Ca2+ dependent. We also investigated whether excess phospholipids could prevent nanocrystal adherence. We found surface loading to occur with a variety of nanocrystal types including iron oxide nanoparticles, quantum dots, and nanophosphors, as well as sizes (10–30 nm) and shapes. Additionally, surface loading occurred over a range of polymer molecular weights (∼30–3000 kDa) and phospholipid carbon tail length. We also show that nanocrystals remain diagnostically active after loading onto the polymer nanospheres, i.e., providing contrast in the case of magnetic resonance imaging for iron oxide nanoparticles and fluorescence for quantum dots. Last, we demonstrated that a fluorescently labeled protein model drug can be delivered by surface loaded nanospheres. We present a platform for contrast media delivery, with the unusual feature that the payload can be controllably localized to the core or the surface. PMID:25188401

  16. Interstitial iron impurities at cores of dissociated dislocations in silicon

    NASA Astrophysics Data System (ADS)

    Ziebarth, Benedikt; Mrovec, Matous; Elsässer, Christian; Gumbsch, Peter

    2015-11-01

    Dislocations play an important role in semiconductor devices made of crystalline silicon (Si). They are known to be strongly performance-limiting defects in solar cell applications, since they act as preferred segregation sites for metallic impurities. In this work we investigate the segregation of iron (Fe) to the cores of the 30° and 90° partial dislocations in Si using atomistic calculations based on first-principles density functional theory. Our simulations show that interstitial Fe impurities segregate readily to all investigated cores and the driving force for the segregation increases with impurity concentration. Moreover, our analysis of the electronic structure reveals the existence of deep defect levels within the band gap that can be related to experimental observations by deep-level transient spectroscopy.

  17. Envelope dynamics of iron-core supernova models

    NASA Technical Reports Server (NTRS)

    Barkat, Z.; Wheeler, J. C.; Buchler, J.-R.; Rakavy, G.

    1974-01-01

    Wilson (1971) has found that the neutrino transport mechanism is unable to generate a supernova explosion in stars with collapsing iron cores. The present work uses Wilson's analysis to investigate the behavior of the overlying potentially explosive layers which Wilson omitted. The outer boundary of the core of Wilson's models moves in such a manner as to deliver a shock to the base of the envelope. We have numerically followed the progress of such shocks into the envelope of a realistic model obtained from evolutionary calculations. We find that only shocks so strong as to be inconsistent with our treatment are capable of ejecting material. For reasonable shocks the nuclear burning does not proceed rapidly at densities below 1,000 kg/cu cm, and the nuclear energy released is less than the shock energy in all models that come near to ejecting matter.

  18. Iron nitride nanoparticles by nanocluster deposition

    SciTech Connect

    Xu Yunhao; Hosein, Sean; Judy, Jack H.; Wang Jianping

    2005-05-15

    Fe{sub 16}N{sub 2} has been reported to have a saturation magnetization as high as 2.8-3.0 T based on molecular beam epitaxy deposited single crystal film. We report on Fe nitride nanoparticles prepared with a gas-aggregation nanocluster deposition technique, which could potentially generate pure metastable Fe{sub 16}N{sub 2} phase nanoparticles. Nitrogen gas has been used to nitride the particles after they have been formed in the cluster source. X-ray diffraction patterns show a peak split of {alpha}-Fe (110) at 52.4 deg. (2{theta}), which indicates the formation of Fe{sub 3}N phase.

  19. The effect of coating on heat generation properties of Iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Yuan, Yuan

    Magnetic nanoparticles have attracted more and more attention for their potential application as heating agents in cancer hyperthermia. The effectiveness of cancer hyperthermia can be increased by using particles that have a higher heat generation rate, quantified by specific absorption rate (SAR), at a smaller applied field. In order to optimize the functionality of nanoparticles as heating agents, it is essential to have a comprehensive understanding of factors that may influence SAR including coating and aggregation. In all biomedical applications, the magnetic particles are coated with surfactants and polymers to enhance biocompatibility, prevent agglomeration and add functionality. Coatings may profoundly influence particles' clustering behavior and magnetic properties. Yet its effect on the heat generation rate of the nanoparticles has been scarcely investigated. In this context, a systematic investigation was carried out in this dissertation in order to understand the impact of the surface coating of magnetic nanoparticles on their heat generation rate. The study also includes investigation of normal nerve cell viability in presence of biofunctionalized magnetic nanoparticles with and without exposure to magnetic heating. Commercially available suspensions of iron oxide nanoparticles with a diameter of approximately 10 nm and different coatings relevant to biomedical applications such as aminosilane, carboxymethyl-dextran, protein A, biotin were extensively characterized. First of all, magnetic phase reduction of magnetite nanoparticles was examined by studying the discrepancy between the volume fraction of magnetic phase calculated from magnetization curve and the magnetic core concentration obtained from Tiron chelation test. The findings indicated that coatings might interact with the surface atoms of the magnetic core and form a magnetically disordered layer reducing the total amount of the magnetic phase. Secondly, the impact of coating and aggregation

  20. 'NC100150', a preparation of iron oxide nanoparticles ideal for positive-contrast MR angiography.

    PubMed

    Kellar, K E; Fujii, D K; Gunther, W H; Briley-Saebø, K; Spiller, M; Koenig, S H

    1999-08-01

    A laboratory-scale synthesis of NC100150 (iron oxide particles with an oxidized starch coating) was characterized by magnetization measurements (vibrating sample magnetometry, VSM), relaxometry (1/T1 NMRD profiles and 1/T2 at 10 and 20 MHz), and dynamic light scattering (photon correlation spectroscopy, PCS). The results were related to give a self-consistent physical description of the particles: a water-impenetrable part making up 12% of the total particle volume, 82% of this volume consisting of an iron oxide core and the remaining 18% consisting of an oxidized starch rind; and, a water-penetrable part making up 88% of the total particle volume, consisting of oxidized starch polymers and entrained water molecules. Relating the magnetization to the relaxometry results required that the oxidized starch coating slows the diffusivity of solvent water molecules in the vicinity of the iron oxide cores. The effect of the organic coating on water diffusivity, not previously considered in the application of relaxation theory to iron oxide nanoparticles, is supported by the much greater (factor of about 2) diameter obtained from the dynamic light scattering measurements in comparison to that obtained from the magnetization measurements. The present work shows that three physical techniques--VSM, relaxometry, and PCS--are needed for properly assessing iron oxide nanoparticles for use as contrast agents for magnetic resonance angiography (MRA). It is also shown that NC100150 has a narrow range of diameters and the smallest value of r2/r1 reported to date, an asset for MRA. PMID:10504049

  1. Magnetization measurements and XMCD studies on ion irradiated iron oxide and core-shell iron/iron-oxide nanomaterials

    SciTech Connect

    Kaur, Maninder; Qiang, You; Jiang, Weilin; Pearce, Carolyn; McCloy, John S.

    2014-12-02

    Magnetite (Fe3O4) and core-shell iron/iron-oxide (Fe/Fe3O4) nanomaterials prepared by a cluster deposition system were irradiated with 5.5 MeV Si2+ ions and the structures determined by x-ray diffraction as consisting of 100% magnetite and 36/64 wt% Fe/FeO, respectively. However, x-ray magnetic circular dichroism (XMCD) indicates similar surfaces in the two samples, slightly oxidized and so having more Fe3+ than the expected magnetite structure, with XMCD intensity much lower for the irradiated core-shell samples indicating weaker magnetism. X-ray absorption spectroscopy (XAS) data lack the signature for FeO, but the irradiated core-shell system consists of Fe-cores with ~13 nm of separating oxide crystallite, so it is likely that FeO exists deeper than the probe depth of the XAS (~5 nm). Exchange bias (Hex) for both samples becomes increasingly negative as temperature is lowered, but the irradiated Fe3O4 sample shows greater sensitivity of cooling field on Hex. Loop asymmetries and Hex sensitivities of the irradiated Fe3O4 sample are due to interfaces and interactions between grains which were not present in samples before irradiation as well as surface oxidation. Asymmetries in the hysteresis curves of the irradiated core/shell sample are related to the reversal mechanism of the antiferromagnetic FeO and possibly some near surface oxidation.

  2. Nanomagnetism of Core-Shell Magnetic Nanoparticles and Application in Spent Nuclear Fuel Separation

    NASA Astrophysics Data System (ADS)

    Tarsem Singh, Maninder Kaur

    This dissertation presents the study on novel core-shell magnetic nanoparticles (NPs) with unique magnetic properties. Understanding the fundamental physics of antiferromagnetic - ferromagnetic interactions is essential to apply in different applications. Chromium (Cr) doped and undoped core-shell iron/iron-oxide NPs have been synthesized using cluster deposition system and studied with respect to their nanostructures, morphologies, sizes, chemical composition and magnetic properties. The room-temperature magnetic properties of Fe based NPs shows the strong dependence of intra/inter-particle interaction on NP size. The Cr-doped Fe NP shows the origin of sigma-FeCr phase at very low Cr concentration (2 at.%) unlike others reported at high Cr content and interaction reversal from dipolar to exchange interaction. A theoretical model of watermelon is constructed based on the experimental results and core-shell NP system in order to explain the physics of exchange interaction in Cr-doped Fe particles. The magnetic nanoparticle---chelator separation nanotechnology is investigated for spent nuclear fuel recycling and is reported 97% and 80% of extraction for Am(III) and Pu(IV) actinides respectively. If the long-term heat generating actinides such as Am(III) can be efficiently removed from the used fuel raffinates, the volume of material that can be placed in a given amount of repository space can be significantly increased. As it is a simple, versatile, compact, and cost efficient process that minimizes secondary waste and improves storage performance.

  3. Synthesis of hafnium oxide-gold core-shell nanoparticles.

    PubMed

    Dahal, Naween; Chikan, Viktor

    2012-01-01

    Developing cheap composite nanoparticle systems that combines a high dielectric constant with good conductivity is important for the future of the electronic industry. In this study, two different sizes, 7.3 ± 2.2 and 5.6 ± 1.9 nm, of HfO(2)@Au core-shell nanoparticles are prepared by using a high-temperature reduction method. The core-shell nanoparticles are characterized by powder X-ray diffraction, high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray analysis (EDX), and UV-visible absorption spectroscopy. HfO(2) exhibits no absorption in the visible region, but the HfO(2)@Au core-shell nanoparticles show a plasmon absorption band at 555 nm that is 25 nm red-shifted as compared to pure gold nanoparticles. According to transmission electron microscopy and energy dispersive X-ray analysis, the HfO(2) particles are coated with approximately three atomic layers of gold.

  4. Synthesis and characterization of platinum decorated iron oxide nanoparticles for biomedical applications

    NASA Astrophysics Data System (ADS)

    Palchoudhury, Soubantika

    This dissertation focuses on the development of a bifunctional nanoparticle system that can potentially offer simultaneous imaging and therapy in the future. Recently, small platinum (Pt) nanoparticles (< 5 nm) have shown great potential in therapeutic applications, such as DNA dissociation, radiation therapy, and oxidative stress treatment. Therefore, the small Pt nanoparticles of size comparable to DNA grooves are chosen as potential therapeutic components in this research. However, such small sized Pt nanoparticles tends to aggregate, and are difficult to target. Therefore, this research reports the synthesis, characterization, and DNA interaction of small Pt decorated iron oxide nanoparticles. The iron oxide carriers provide stability to the small Pt nanoparticles, and can potentially serve as MRI contrast agents. The hypothesis of this research is that the Pt nanoparticles supported on iron oxide nanoparticle surfaces can effectively interact with DNA molecules similar to the free Pt nanoparticles. A reproducible synthetic technique was first developed to prepare iron oxide nanoparticles with excellent size control and narrow size distribution. Subsequently, two different approaches were utilized to produce multiple small Pt nanoparticle attached iron oxide nanoparticles. The first route involved attachment of Pt nanoparticles onto iron oxide seeds of various shapes in an organic solvent, followed by an aqueous phase transfer. Here, the shape of the nanoparticles was controlled to facilitate heterogeneous nucleation of Pt nanoparticles. The protective biocompatible polymer coating (polyacrylic acid) in this method could prevent interaction of the Pt nanoparticles with undesirable biomolecules. Several non-spherical iron oxide nanoparticles were explored, including whiskers, worms, plates, and flowers. In the second method, an aqueous phase ligand exchange process was performed first, prior to the deposition of multiple Pt nanoparticles. This facile method

  5. Solid lipid nanoparticles loaded with iron to overcome barriers for treatment of iron deficiency anemia

    PubMed Central

    Hosny, Khaled Mohamed; Banjar, Zainy Mohammed; Hariri, Amani H; Hassan, Ali Habiballah

    2015-01-01

    According to the World Health Organization, 46% of the world’s children suffer from anemia, which is usually treated with iron supplements such as ferrous sulfate. The aim of this study was to prepare iron as solid lipid nanoparticles, in order to find an innovative way for alleviating the disadvantages associated with commercially available tablets. These limitations include adverse effects on the digestive system resulting in constipation and blood in the stool. The second drawback is the high variability in the absorption of iron and thus in its bioavailability. Iron solid lipid nanoparticles (Fe-SLNs) were prepared by hot homogenization/ultrasonication. Solubility of ferrous sulfate in different solid lipids was measured, and effects of process variables such as the surfactant type and concentration, homogenization and ultrasonication times, and charge-inducing agent on the particle size, zeta potential, and encapsulation efficiency were determined. Furthermore, in vitro drug release and in vivo pharmacokinetics were studied in rabbits. Results indicated that Fe-SLNs consisted of 3% Compritol 888 ATO, 1% Lecithin, 3% Poloxamer 188, and 0.2% dicetylphosphate, with an average particle size of 25 nm with 92.3% entrapment efficiency. In vivo pharmacokinetic study revealed more than fourfold enhanced bioavailability. In conclusion, Fe-SLNs could be a promising carrier for iron with enhanced oral bioavailability. PMID:25609917

  6. Suppressing iron oxide nanoparticle toxicity by vascular targeted antioxidant polymer nanoparticles.

    PubMed

    Cochran, David B; Wattamwar, Paritosh P; Wydra, Robert; Hilt, J Zach; Anderson, Kimberly W; Eitel, Richard E; Dziubla, Thomas D

    2013-12-01

    The biomedical use of superparamagnetic iron oxide nanoparticles has been of continued interest in the literature and clinic. Their ability to be used as contrast agents for imaging and/or responsive agents for remote actuation makes them exciting materials for a wide range of clinical applications. Recently, however, concern has arisen regarding the potential health effects of these particles. Iron oxide toxicity has been demonstrated in in vivo and in vitro models, with oxidative stress being implicated as playing a key role in this pathology. One of the key cell types implicated in this injury is the vascular endothelial cells. Here, we report on the development of a targeted polymeric antioxidant, poly(trolox ester), nanoparticle that can suppress oxidative damage. As the polymer undergoes enzymatic hydrolysis, active trolox is locally released, providing a long term protection against pro-oxidant agents. In this work, poly(trolox) nanoparticles are targeted to platelet endothelial cell adhesion molecules (PECAM-1), which are able to bind to and internalize in endothelial cells and provide localized protection against the cytotoxicity caused by iron oxide nanoparticles. These results indicate the potential of using poly(trolox ester) as a means of mitigating iron oxide toxicity, potentially expanding the clinical use and relevance of these exciting systems.

  7. Design of Super-Paramagnetic Core-Shell Nanoparticles for Enhanced Performance of Inverted Polymer Solar Cells.

    PubMed

    Jaramillo, Johny; Boudouris, Bryan W; Barrero, César A; Jaramillo, Franklin

    2015-11-18

    Controlling the nature and transfer of excited states in organic photovoltaic (OPV) devices is of critical concern due to the fact that exciton transport and separation can dictate the final performance of the system. One effective method to accomplish improved charge separation in organic electronic materials is to control the spin state of the photogenerated charge-carrying species. To this end, nanoparticles with unique iron oxide (Fe3O4) cores and zinc oxide (ZnO) shells were synthesized in a controlled manner. Then, the structural and magnetic properties of these core-shell nanoparticles (Fe3O4@ZnO) were tuned to ensure superior performance when they were incorporated into the active layers of OPV devices. Specifically, small loadings of the core-shell nanoparticles were blended with the previously well-characterized OPV active layer of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). Upon addition of the core-shell nanoparticles, the performance of the OPV devices was increased up to 25% relative to P3HT-PCBM active layer devices that contained no nanoparticles; this increase was a direct result of an increase in the short-circuit current densities of the devices. Furthermore, it was demonstrated that the increase in photocurrent was not due to enhanced absorption of the active layer due to the presence of the Fe3O4@ZnO core-shell nanoparticles. In fact, this increase in device performance occurred because of the presence of the superparamagnetic Fe3O4 in the core of the nanoparticles as incorporation of ZnO only nanoparticles did not alter the device performance. Importantly, however, the ZnO shell of the nanoparticles mitigated the negative optical effect of Fe3O4, which have been observed previously. This allowed the core-shell nanoparticles to outperform bare Fe3O4 nanoparticles when the single-layer nanoparticles were incorporated into the active layer of OPV devices. As such, the new materials described here present a

  8. Magnesium solubility in metallic iron during core formation

    NASA Astrophysics Data System (ADS)

    Badro, J.; Siebert, J.; Nimmo, F.

    2015-12-01

    Terrestrial core formation occurred by gravitational segregation of immiscible metal and silicate melts in an extensively molten proto-Earth. This stripped the bulk silicate Earth of most of its siderophile elements, which were concentrated in the core. The process occurs by virtue of partitioning through a redox reaction (e.g. [1]) whereby iron in the metal exchanges for a bonded siderophile element in the mantle. By performing metal-silicate equilibration experiments at extreme pressures and temperatures using the laser-heated diamond anvil cell, we find that the major lithophile component of the silicate Earth, namely MgO, can also become soluble in the metal. At close to 5000 K, our experiments show that up to 1.2 % MgO can be incorporated in the metal. We show that Mg incorporation in the metal isn't a redox reaction as with siderophile element partitioning, but rather a direct solubility of the MgO component as temperatures approach the metal-silicate solvus; in that respect, our results are fully consistent with the recently calculated Fe-MgO solvus [2]. This confirms that significant amounts of magnesium could have been added to the early core, provided that a giant impact had generated the necessary temperature increase. The subsequent exsolution of MgO driven by core cooling would have provided a significant buoyancy source, likely sufficient to drive core convection and producing an ancient magnetic field [3]. [1] J. Wade and B. J. Wood, Earth Planet. Sci. Lett., 236, 78-95 (2005) [2] S. M. Wahl and B. Militzer, Earth Planet. Sci. Lett. 410, 25-33 (2015) [3] D. J. Stevenson, DI11C-03, Fall AGU 2012.

  9. Highly Stable Amine Functionalized Iron Oxide Nanoparticles Designed for Magnetic Particle Imaging (MPI)

    PubMed Central

    Arami, Hamed; Krishnan, Kannan M.

    2014-01-01

    Magnetic particle imaging (MPI) is a promising medical imaging technology that uses iron oxide nanoparticles (NPs) as clinically safe tracers. The core and hydrodynamic size of these NPs determine the signal intensity and spatial resolution in MPI, whilst their monodispersity when preserved during the biomedical applications, generates a consistently high quality MPI image. Using an effective process to coat the synthesized NPs with amine terminated PEG molecules, we show by dynamic light scattering (DLS) that they are water-soluble with long-term stability in biological media such as phosphate buffered saline (PBS) and sodium bicarbonate buffers and Dulbecco’s modified Eagle medium (DMEM) enriched with 10% fetal bovine serum (FBS). Further, using magnetic particle spectroscopy (MPS), to measure the particle response function (PRF), defined as the derivative of the magnetization of the nanoparticles, we predict the MPI performance of these nanoparticles at a driving field frequency of 25 kHz. The MPS efficacy of the functionalized nanoparticles was also monitored over time, and both signal intensity and resolution remained unchanged even after seven days of incubation. This is attributed to the dominant contribution of the Néel relaxation mechanism of the monodisperse and highly stable nanoparticles, which was preserved through the incubation period. PMID:25554710

  10. Synthesis and characterization of metal-carbon core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, He

    Superparamagnetic nanoparticles have been actively investigated as the contrast agents for Magnetic Resonance Imaging (MRI) since the last decade owing to their relatively high magnetic susceptibility, longer retention in the blood stream and better toxicity profile compared to gadolinium-based contrast agents. Most research in this regard has been focused on iron oxides primarily because nanoparticles made of materials that have higher saturation magnetization are usually prone to degradation due to oxidation and are difficult to retain under ambient conditions. Attempts to preserve the high saturation magnetization phases have been made through passivating the surface of the nanoparticles with Au or oxides. However, these approaches are not very effective. In this work, the synthesis, structures, compositions, magnetic properties and potential applications of some metallic nanoparticles, stabilized with protective graphitic carbons, have been studied. Fe, Co, FexCo(1-x) and AuxFe (1-x) alloy nanoparticles encapsulated by graphitic carbon are synthesized by chemical vapor deposition. Transmission electron microscopy (TEM) reveals that the nanoparticles are mostly about 10 nm in diameter and each nanoparticle is enclosed by at least one layer of graphitic carbon. Phase identification by high resolution TEM indicates the metallic phases were indeed obtained and preserved, even after three years of exposure to ambient conditions. The Fe-containing nanoparticles were found to be either BCC or FCC or Fe 3C, the Co nanoparticles being FCC, the FexCo(1-x) (0.1 < x < 0.6) nanoparticles being BCC alloys and AuxFe (1-x) (0.2 < x < 0.8) nanoparticles being FCC alloys. Energy dispersive spectrometry analysis of the Au0.67Fe0.33 nanoparticles indicates the composition of nanoparticles is consistent with the molar ratio of metal precursors, while quantitative EELS analysis suggest that the composition distribution of FexCo(1-x) rather wide. Preliminary Energy-Filtered TEM

  11. Synthesis of Organic Dye-Impregnated Silica Shell-Coated Iron Oxide Nanoparticles by a New Method

    NASA Astrophysics Data System (ADS)

    Ren, Cuiling; Li, Jinhua; Liu, Qian; Ren, Juan; Chen, Xingguo; Hu, Zhide; Xue, Desheng

    2008-12-01

    A new method for preparing magnetic iron oxide nanoparticles coated by organic dye-doped silica shell was developed in this article. Iron oxide nanoparticles were first coated with dye-impregnated silica shell by the hydrolysis of hexadecyltrimethoxysilane (HTMOS) which produced a hydrophobic core for the entrapment of organic dye molecules. Then, the particles were coated with a hydrophilic shell by the hydrolysis of tetraethylorthosilicate (TEOS), which enabled water dispersal of the resulting nanoparticles. The final product was characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, photoluminescence spectroscopy, and vibration sample magnetometer. All the characterization results proved the final samples possessed magnetic and fluorescent properties simultaneously. And this new multifunctional nanomaterial possessed high photostability and minimal dye leakage.

  12. Single-shell carbon-encapsulated iron nanoparticles: synthesis and high electrocatalytic activity for hydrogen evolution reaction.

    PubMed

    Tavakkoli, Mohammad; Kallio, Tanja; Reynaud, Olivier; Nasibulin, Albert G; Johans, Christoffer; Sainio, Jani; Jiang, Hua; Kauppinen, Esko I; Laasonen, Kari

    2015-04-01

    Efficient hydrogen evolution reaction (HER) through effective and inexpensive electrocatalysts is a valuable approach for clean and renewable energy systems. Here, single-shell carbon-encapsulated iron nanoparticles (SCEINs) decorated on single-walled carbon nanotubes (SWNTs) are introduced as a novel highly active and durable non-noble-metal catalyst for the HER. This catalyst exhibits catalytic properties superior to previously studied nonprecious materials and comparable to those of platinum. The SCEIN/SWNT is synthesized by a novel fast and low-cost aerosol chemical vapor deposition method in a one-step synthesis. In SCEINs the single carbon layer does not prevent desired access of the reactants to the vicinity of the iron nanoparticles but protects the active metallic core from oxidation. This finding opens new avenues for utilizing active transition metals such as iron in a wide range of applications. PMID:25683139

  13. Characterization of insoluble nanoparticles in Antarctic ice cores

    NASA Astrophysics Data System (ADS)

    Ellis, A.; Edwards, R.; Van Riessen, A.; Saunders, M.; Smith, A. M.; Curran, M. A.; Goodwin, I. D.; Feiteng, W.

    2013-12-01

    Insoluble nanoparticles in the form of aerosols have significant effects on climate and biogeochemical cycles. Records of these aerosols are essential for understanding paleoclimate forcing and future climate change. These particles and their precursors are emitted to the atmosphere from a variety of primary and secondary sources including biomass burning as well as biogenic, anthropogenic, volcanic, extraterrestrial, and terrestrial mineral emissions. While a large body of research exists with respect to mineral dust particles (on the micrometer scale) derived from ice and sediment cores, very little is known with regards to the history of insoluble particles on the nano scale. Ice core records are the only reliable way to study the past history of these particles. Here, we will present new data regarding the physical and chemical properties of nanoparticles found in ice cores from East Antarctica.

  14. Iron oxide nanoparticles stabilized with a bilayer of oleic acid for magnetic hyperthermia and MRI applications

    NASA Astrophysics Data System (ADS)

    Soares, Paula I. P.; Laia, César A. T.; Carvalho, Alexandra; Pereira, Laura C. J.; Coutinho, Joana T.; Ferreira, Isabel M. M.; Novo, Carlos M. M.; Borges, João Paulo

    2016-10-01

    Iron oxide nanoparticles (Fe3O4, IONPs) are promising candidates for several biomedical applications such as magnetic hyperthermia and as contrast agents for magnetic resonance imaging (MRI). However, their colloidal stability in physiological conditions hinders their application requiring the use of biocompatible surfactant agents. The present investigation focuses on obtaining highly stable IONPs, stabilized by the presence of an oleic acid bilayer. Critical aspects such as oleic acid concentration and pH were optimized to ensure maximum stability. NPs composed of an iron oxide core with an average diameter of 9 nm measured using transmission electron microscopy (TEM) form agglomerates with an hydrodynamic diameter of around 170 nm when dispersed in water in the presence of an oleic acid bilayer, remaining stable (zeta potential of -120 mV). Magnetic hyperthermia and the relaxivities measurements show high efficiency at neutral pH which enables their use for both magnetic hyperthermia and MRI.

  15. Synthesis, characterization, applications, and challenges of iron oxide nanoparticles.

    PubMed

    Ali, Attarad; Zafar, Hira; Zia, Muhammad; Ul Haq, Ihsan; Phull, Abdul Rehman; Ali, Joham Sarfraz; Hussain, Altaf

    2016-01-01

    Recently, iron oxide nanoparticles (NPs) have attracted much consideration due to their unique properties, such as superparamagnetism, surface-to-volume ratio, greater surface area, and easy separation methodology. Various physical, chemical, and biological methods have been adopted to synthesize magnetic NPs with suitable surface chemistry. This review summarizes the methods for the preparation of iron oxide NPs, size and morphology control, and magnetic properties with recent bioengineering, commercial, and industrial applications. Iron oxides exhibit great potential in the fields of life sciences such as biomedicine, agriculture, and environment. Nontoxic conduct and biocompatible applications of magnetic NPs can be enriched further by special surface coating with organic or inorganic molecules, including surfactants, drugs, proteins, starches, enzymes, antibodies, nucleotides, nonionic detergents, and polyelectrolytes. Magnetic NPs can also be directed to an organ, tissue, or tumor using an external magnetic field for hyperthermic treatment of patients. Keeping in mind the current interest in iron NPs, this review is designed to report recent information from synthesis to characterization, and applications of iron NPs. PMID:27578966

  16. Synthesis, characterization, applications, and challenges of iron oxide nanoparticles

    PubMed Central

    Ali, Attarad; Zafar, Hira; Zia, Muhammad; ul Haq, Ihsan; Phull, Abdul Rehman; Ali, Joham Sarfraz; Hussain, Altaf

    2016-01-01

    Recently, iron oxide nanoparticles (NPs) have attracted much consideration due to their unique properties, such as superparamagnetism, surface-to-volume ratio, greater surface area, and easy separation methodology. Various physical, chemical, and biological methods have been adopted to synthesize magnetic NPs with suitable surface chemistry. This review summarizes the methods for the preparation of iron oxide NPs, size and morphology control, and magnetic properties with recent bioengineering, commercial, and industrial applications. Iron oxides exhibit great potential in the fields of life sciences such as biomedicine, agriculture, and environment. Nontoxic conduct and biocompatible applications of magnetic NPs can be enriched further by special surface coating with organic or inorganic molecules, including surfactants, drugs, proteins, starches, enzymes, antibodies, nucleotides, nonionic detergents, and polyelectrolytes. Magnetic NPs can also be directed to an organ, tissue, or tumor using an external magnetic field for hyperthermic treatment of patients. Keeping in mind the current interest in iron NPs, this review is designed to report recent information from synthesis to characterization, and applications of iron NPs. PMID:27578966

  17. Exchange bias in Core-Shell Iron-Iron Oxide Nanoclusters

    SciTech Connect

    Kaur, Maninder; McCloy, John S.; Qiang, You

    2013-04-03

    An exchange bias study has been performed on core-shell iron-iron oxide (Fe-Fe3O4) nanoclusters (NCs) of size 11 nm and 14 nm carrying a different core to shell ratio. NCs show complicated behaviors due to competition between interfacial exchange and Zeeman energy in the presence of magnetic field during cooling. These behaviors are accompanied by the evolution of size- dependent cluster structures in the ferromagnetic-core/ferri- or antiferro-magnetic-shell. Smaller clusters have larger coercive field, exchange bias field, and vertical magnetization shift due to the greater contribution from frozen spins of shell/interfaces. These smaller clusters thus also show more dramatic changes with the training effect. Both sizes of clusters display an additional anomaly of the upper part of the hysteresis loop at 10 K under low cooling field (0.1 kOe). This anomaly decreases with number of loop cycles with same field, and disappear with large cooling field (> 0.1 kOe). It may be caused by the competition between the magnetization reversal and the magnetostatic interactions.

  18. Synthesis of Iron Nanoparticles Using Azadirachta indica Extract and Its Catalytic Activity Toward Nitrophenol Reduction.

    PubMed

    Karthikeyan, C; Ranjani, M; Kim, Ae Rhan; Yoo, Dong Jin; Kumar, G Gnana

    2016-03-01

    A simple, hasty and eco-friendly approach for the synthesis of iron nanoparticles has been developed using the medicinally important Azadirachta indica extract, which act as both reducing and stabilizing agent. The formation and morphological properties of iron nanoparticles as a function of metallic precursor and Azadirachta indica extract concentration have been investigated. The influence of solvent over the size and texture of iron nanoparticles has also been evaluated in detail. The thermal behavior of prepared nanoparticles was identified from thermogravimetric analysis. Furthermore, the catalytic activity of prepared iron nanoparticles toward the reduction of p-nitrophenol was analyzed and the reduction process was occurred within 30 sec. The cost and time efficient biosynthesis process and excellent catalytic activity of the prepared iron nanoparticles construct this protocol attractive.

  19. Possible thermal and chemical stabilization of body-centred-cubic iron in the Earth's core.

    PubMed

    Vocadlo, Lidunka; Alfè, Dario; Gillan, M J; Wood, I G; Brodholt, J P; Price, G David

    2003-07-31

    The nature of the stable phase of iron in the Earth's solid inner core is still highly controversial. Laboratory experiments suggest the possibility of an uncharacterized phase transformation in iron at core conditions and seismological observations have indicated the possible presence of complex, inner-core layering. Theoretical studies currently suggest that the hexagonal close packed (h.c.p.) phase of iron is stable at core pressures and that the body centred cubic (b.c.c.) phase of iron becomes elastically unstable at high pressure. In other h.c.p. metals, however, a high-pressure b.c.c. form has been found to become stabilized at high temperature. We report here a quantum mechanical study of b.c.c.-iron able to model its behaviour at core temperatures as well as pressures, using ab initio molecular dynamics free-energy calculations. We find that b.c.c.-iron indeed becomes entropically stabilized at core temperatures, but in its pure state h.c.p.-iron still remains thermodynamically more favourable. The inner core, however, is not pure iron, and our calculations indicate that the b.c.c. phase will be stabilized with respect to the h.c.p. phase by sulphur or silicon impurities in the core. Consequently, a b.c.c.-structured alloy may be a strong candidate for explaining the observed seismic complexity of the inner core.

  20. Effective delivery of immunosuppressive drug molecules by silica coated iron oxide nanoparticles.

    PubMed

    Hwang, Jangsun; Lee, Eunwon; Kim, Jieun; Seo, Youngmin; Lee, Kwan Hong; Hong, Jong Wook; Gilad, Assaf A; Park, Hansoo; Choi, Jonghoon

    2016-06-01

    Iron oxide nanoparticles have been used in a wide range of biomedical applications, including drug delivery, molecular imaging, and cellular imaging. Various surface modifications have been applied to the particles to stabilize their surface and to give them a moiety for anchoring tags and/or drug molecules. Conventional methods of delivering immunosuppressant drugs often require a high dose of drugs to ensure therapeutic effects, but this can lead to toxic side effects. In this study, we used silica-coated iron oxide nanoparticles (IOSs) for a drug delivery application in which the nanoparticles carry the minimum amount of drug required to be effective to the target cells. IOSs could be loaded with water-insoluble immunosuppressive drug molecules (MPA: mycophenolic acid) and be used as a contrast agent for MRI. We characterized the IOSs for their physicochemical properties and found their average hydrodynamic diameter and core size to be 40.5nm and 5nm, respectively. Following the introduction of MPA-loaded IOSs (IOS/M), we evaluated the secretion dynamics of cytokines from peripheral blood mononuclear cells stimulated with phytohemagglutinin (PHA). The results showed that IOS/M effectively inhibited the secretion of the cytokines interleukin-2 and tumor necrosis factor α, with a minimal concentration of MPA. In conclusion, IOS/M may have potential applications in both efficient drug delivery and MRI. PMID:26966999

  1. Chondroitin sulfate-capped super-paramagnetic iron oxide nanoparticles as potential carriers of doxorubicin hydrochloride.

    PubMed

    Mallick, Neha; Anwar, Mohammed; Asfer, Mohammed; Mehdi, Syed Hassan; Rizvi, Mohammed Moshahid Alam; Panda, Amulya Kumar; Talegaonkar, Sushama; Ahmad, Farhan Jalees

    2016-10-20

    Chondroitin-4-sulfate (CS), a glycosaminoglycan, was used to prepare CS-capped super-paramagnetic iron oxide nanoparticles, which were further employed for loading a water-soluble chemotherapeutic agent (doxorubicin hydrochloride, DOX). CS-capped SPIONs have potential biomedical application in cancer targeting. The optimized formulation had a hydrodynamic size of 91.2±0.8nm (PDI; 0.228±0.004) and zeta potential of -49.1±1.66mV. DOX was loaded onto the formulation up to 2% (w/w) by physical interaction with CS. TEM showed nano-sized particles having a core-shell structure. XRD confirmed crystal phase of iron oxide. FT-IR conceived the interaction of iron oxide with CS as bidentate chelation and also confirmed DOX loading. Vibration sample magnetometry confirmed super-paramagnetic nature of nanoparticles, with saturation magnetization of 0.238emug(-1). In vitro release profile at pH 7.4 showed that 96.67% of DOX was released within 24h (first order kinetics). MTT assay in MCF7 cells showed significantly higher (p<0.0001) cytotoxicity for DOX in SPIONs than DOX solution (IC50 values 6.294±0.4169 and 11.316±0.1102μgmL(-1), respectively). PMID:27474599

  2. Complex coacervate core micelles from iron-based coordination polymers.

    PubMed

    Wang, Junyou; de Keizer, Arie; Fokkink, Remco; Yan, Yun; Cohen Stuart, Martien A; van der Gucht, Jasper

    2010-07-01

    Complex coacervate core micelles (C3Ms) from cationic poly(N-methyl-2-vinyl-pyridinium iodide)-b-poly(ethylene oxide) (P2MVP(41)-b-PEO(205)) and anionic iron coordination polymers are investigated in the present work. Micelle formation is studied by light scattering for both Fe(II)- and Fe(III)-containing C3Ms. At the stoichiometric charge ratio, both Fe(II)-C3Ms and Fe(III)-C3Ms are stable for at least 1 week at room temperature. Excess of iron coordination polymers has almost no effect on the formed Fe(II)-C3Ms and Fe(III)-C3Ms, whereas excess of P2MVP(41)-b-PEO(205) copolymers in the solution can dissociate the formed micelles. Upon increasing salt concentration, the scattering intensity decreases. This decrease is due to both a decrease in the number of micelles (or an increase in CMC) and a decrease in aggregation number. The salt dependence of the CMC and the aggregation number is explained using a scaling argument for C3M formation. Compared with Fe(II)-C3Ms, Fe(III)-C3Ms have a lower CMC and a higher stability against dissociation by added salt.

  3. Development of a lauric acid/albumin hybrid iron oxide nanoparticle system with improved biocompatibility.

    PubMed

    Zaloga, Jan; Janko, Christina; Nowak, Johannes; Matuszak, Jasmin; Knaup, Sabine; Eberbeck, Dietmar; Tietze, Rainer; Unterweger, Harald; Friedrich, Ralf P; Duerr, Stephan; Heimke-Brinck, Ralph; Baum, Eva; Cicha, Iwona; Dörje, Frank; Odenbach, Stefan; Lyer, Stefan; Lee, Geoffrey; Alexiou, Christoph

    2014-01-01

    The promising potential of superparamagnetic iron oxide nanoparticles (SPIONs) in various nanomedical applications has been frequently reported. However, although many different synthesis methods, coatings, and functionalization techniques have been described, not many core-shell SPION drug delivery systems are available for clinicians at the moment. Here, bovine serum albumin was adsorbed onto lauric acid-stabilized SPIONs. The agglomeration behavior, zeta potential, and their dependence on the synthesis conditions were characterized with dynamic light scattering. The existence and composition of the core-shell-matrix structure was investigated by transmission electron microscopy, Fourier transform infrared spectroscopy, and zeta potential measurements. We showed that the iron oxide cores form agglomerates in the range of 80 nm. Moreover, despite their remarkably low tendency to aggregate even in a complex media like whole blood, the SPIONs still maintained their magnetic properties and were well attractable with a magnet. The magnetic properties were quantified by vibrating sample magnetometry and a superconducting quantum interference device. Using flow cytometry, we further investigated the effects of the different types of nanoparticle coating on morphology, viability, and DNA integrity of Jurkat cells. We showed that by addition of bovine serum albumin, the toxicity of nanoparticles is greatly reduced. We also investigated the effect of the particles on the growth of primary human endothelial cells to further demonstrate the biocompatibility of the particles. As proof of principle, we showed that the hybrid-coated particles are able to carry payloads of up to 800 μg/mL of the cytostatic drug mitoxantrone while still staying colloidally stable. The drug-loaded system exhibited excellent therapeutic potential in vitro, exceeding that of free mitoxantrone. In conclusion, we have synthesized a biocompatible ferrofluid that shows great potential for clinical

  4. Development of a lauric acid/albumin hybrid iron oxide nanoparticle system with improved biocompatibility

    PubMed Central

    Zaloga, Jan; Janko, Christina; Nowak, Johannes; Matuszak, Jasmin; Knaup, Sabine; Eberbeck, Dietmar; Tietze, Rainer; Unterweger, Harald; Friedrich, Ralf P; Duerr, Stephan; Heimke-Brinck, Ralph; Baum, Eva; Cicha, Iwona; Dörje, Frank; Odenbach, Stefan; Lyer, Stefan; Lee, Geoffrey; Alexiou, Christoph

    2014-01-01

    The promising potential of superparamagnetic iron oxide nanoparticles (SPIONs) in various nanomedical applications has been frequently reported. However, although many different synthesis methods, coatings, and functionalization techniques have been described, not many core-shell SPION drug delivery systems are available for clinicians at the moment. Here, bovine serum albumin was adsorbed onto lauric acid-stabilized SPIONs. The agglomeration behavior, zeta potential, and their dependence on the synthesis conditions were characterized with dynamic light scattering. The existence and composition of the core-shell-matrix structure was investigated by transmission electron microscopy, Fourier transform infrared spectroscopy, and zeta potential measurements. We showed that the iron oxide cores form agglomerates in the range of 80 nm. Moreover, despite their remarkably low tendency to aggregate even in a complex media like whole blood, the SPIONs still maintained their magnetic properties and were well attractable with a magnet. The magnetic properties were quantified by vibrating sample magnetometry and a superconducting quantum interference device. Using flow cytometry, we further investigated the effects of the different types of nanoparticle coating on morphology, viability, and DNA integrity of Jurkat cells. We showed that by addition of bovine serum albumin, the toxicity of nanoparticles is greatly reduced. We also investigated the effect of the particles on the growth of primary human endothelial cells to further demonstrate the biocompatibility of the particles. As proof of principle, we showed that the hybrid-coated particles are able to carry payloads of up to 800 μg/mL of the cytostatic drug mitoxantrone while still staying colloidally stable. The drug-loaded system exhibited excellent therapeutic potential in vitro, exceeding that of free mitoxantrone. In conclusion, we have synthesized a biocompatible ferrofluid that shows great potential for clinical

  5. Development of a lauric acid/albumin hybrid iron oxide nanoparticle system with improved biocompatibility.

    PubMed

    Zaloga, Jan; Janko, Christina; Nowak, Johannes; Matuszak, Jasmin; Knaup, Sabine; Eberbeck, Dietmar; Tietze, Rainer; Unterweger, Harald; Friedrich, Ralf P; Duerr, Stephan; Heimke-Brinck, Ralph; Baum, Eva; Cicha, Iwona; Dörje, Frank; Odenbach, Stefan; Lyer, Stefan; Lee, Geoffrey; Alexiou, Christoph

    2014-01-01

    The promising potential of superparamagnetic iron oxide nanoparticles (SPIONs) in various nanomedical applications has been frequently reported. However, although many different synthesis methods, coatings, and functionalization techniques have been described, not many core-shell SPION drug delivery systems are available for clinicians at the moment. Here, bovine serum albumin was adsorbed onto lauric acid-stabilized SPIONs. The agglomeration behavior, zeta potential, and their dependence on the synthesis conditions were characterized with dynamic light scattering. The existence and composition of the core-shell-matrix structure was investigated by transmission electron microscopy, Fourier transform infrared spectroscopy, and zeta potential measurements. We showed that the iron oxide cores form agglomerates in the range of 80 nm. Moreover, despite their remarkably low tendency to aggregate even in a complex media like whole blood, the SPIONs still maintained their magnetic properties and were well attractable with a magnet. The magnetic properties were quantified by vibrating sample magnetometry and a superconducting quantum interference device. Using flow cytometry, we further investigated the effects of the different types of nanoparticle coating on morphology, viability, and DNA integrity of Jurkat cells. We showed that by addition of bovine serum albumin, the toxicity of nanoparticles is greatly reduced. We also investigated the effect of the particles on the growth of primary human endothelial cells to further demonstrate the biocompatibility of the particles. As proof of principle, we showed that the hybrid-coated particles are able to carry payloads of up to 800 μg/mL of the cytostatic drug mitoxantrone while still staying colloidally stable. The drug-loaded system exhibited excellent therapeutic potential in vitro, exceeding that of free mitoxantrone. In conclusion, we have synthesized a biocompatible ferrofluid that shows great potential for clinical

  6. Handling of iron oxide and silver nanoparticles by astrocytes.

    PubMed

    Hohnholt, Michaela C; Geppert, Mark; Luther, Eva M; Petters, Charlotte; Bulcke, Felix; Dringen, Ralf

    2013-02-01

    Metal-containing nanoparticles (NPs) are currently used for various biomedical applications. Since such NPs are able to enter the brain, the cells of this organ have to deal with NPs and with NP-derived metal ions. In brain, astrocytes are considered to play a key function in regulating metal homeostasis and in protecting other brain cells against metal toxicity. Thus, among the different types of brain cells, especially astrocytes are of interest regarding the uptake and the handling of metal-containing NPs. This article summarizes the current knowledge on the consequences of an exposure of astrocytes to NPs. Special focus will be given to magnetic iron oxide nanoparticles (IONPs) and silver nanoparticles (AgNPs), since the biocompatibility of these NPs has been studied for astrocytes in detail. Cultured astrocytes efficiently accumulate IONPs and AgNPs in a time-, concentration- and temperature-dependent manner by endocytotic processes. Astrocytes are neither acutely damaged by the exposure to high concentrations of NPs nor by the prolonged intracellular presence of large amounts of accumulated NPs. Although metal ions are liberated from accumulated NPs, NP-derived iron and silver ions are not exported from astrocytes but are rather stored in proteins such as ferritin and metallothioneins which are synthesized in NP-treated astrocytes. The efficient accumulation of large amounts of metal-containing NPs and the upregulation of proteins that safely store NP-derived metal ions suggest that astrocytes protect the brain against the potential toxicity of metal-containing NPs.

  7. Thermal and magnetic properties of chitosan-iron oxide nanoparticles.

    PubMed

    Soares, Paula I P; Machado, Diana; Laia, César; Pereira, Laura C J; Coutinho, Joana T; Ferreira, Isabel M M; Novo, Carlos M M; Borges, João Paulo

    2016-09-20

    Chitosan is a biopolymer widely used for biomedical applications such as drug delivery systems, wound healing, and tissue engineering. Chitosan can be used as coating for other types of materials such as iron oxide nanoparticles, improving its biocompatibility while extending its range of applications. In this work iron oxide nanoparticles (Fe3O4 NPs) produced by chemical precipitation and thermal decomposition and coated with chitosan with different molecular weights were studied. Basic characterization on bare and chitosan-Fe3O4 NPs was performed demonstrating that chitosan does not affect the crystallinity, chemical composition, and superparamagnetic properties of the Fe3O4 NPs, and also the incorporation of Fe3O4 NPs into chitosan nanoparticles increases the later hydrodynamic diameter without compromising its physical and chemical properties. The nano-composite was tested for magnetic hyperthermia by applying an alternating current magnetic field to the samples demonstrating that the heating ability of the Fe3O4 NPs was not significantly affected by chitosan.

  8. Experimental determination of the electrical resistivity of iron at Earth's core conditions.

    PubMed

    Ohta, Kenji; Kuwayama, Yasuhiro; Hirose, Kei; Shimizu, Katsuya; Ohishi, Yasuo

    2016-06-01

    Earth continuously generates a dipole magnetic field in its convecting liquid outer core by a self-sustained dynamo action. Metallic iron is a dominant component of the outer core, so its electrical and thermal conductivity controls the dynamics and thermal evolution of Earth's core. However, in spite of extensive research, the transport properties of iron under core conditions are still controversial. Since free electrons are a primary carrier of both electric current and heat, the electron scattering mechanism in iron under high pressure and temperature holds the key to understanding the transport properties of planetary cores. Here we measure the electrical resistivity (the reciprocal of electrical conductivity) of iron at the high temperatures (up to 4,500 kelvin) and pressures (megabars) of Earth's core in a laser-heated diamond-anvil cell. The value measured for the resistivity of iron is even lower than the value extrapolated from high-pressure, low-temperature data using the Bloch-Grüneisen law, which considers only the electron-phonon scattering. This shows that the iron resistivity is strongly suppressed by the resistivity saturation effect at high temperatures. The low electrical resistivity of iron indicates the high thermal conductivity of Earth's core, suggesting rapid core cooling and a young inner core less than 0.7 billion years old. Therefore, an abrupt increase in palaeomagnetic field intensity around 1.3 billion years ago may not be related to the birth of the inner core. PMID:27251282

  9. Experimental determination of the electrical resistivity of iron at Earth’s core conditions

    NASA Astrophysics Data System (ADS)

    Ohta, Kenji; Kuwayama, Yasuhiro; Hirose, Kei; Shimizu, Katsuya; Ohishi, Yasuo

    2016-06-01

    Earth continuously generates a dipole magnetic field in its convecting liquid outer core by a self-sustained dynamo action. Metallic iron is a dominant component of the outer core, so its electrical and thermal conductivity controls the dynamics and thermal evolution of Earth’s core. However, in spite of extensive research, the transport properties of iron under core conditions are still controversial. Since free electrons are a primary carrier of both electric current and heat, the electron scattering mechanism in iron under high pressure and temperature holds the key to understanding the transport properties of planetary cores. Here we measure the electrical resistivity (the reciprocal of electrical conductivity) of iron at the high temperatures (up to 4,500 kelvin) and pressures (megabars) of Earth’s core in a laser-heated diamond-anvil cell. The value measured for the resistivity of iron is even lower than the value extrapolated from high-pressure, low-temperature data using the Bloch-Grüneisen law, which considers only the electron-phonon scattering. This shows that the iron resistivity is strongly suppressed by the resistivity saturation effect at high temperatures. The low electrical resistivity of iron indicates the high thermal conductivity of Earth’s core, suggesting rapid core cooling and a young inner core less than 0.7 billion years old. Therefore, an abrupt increase in palaeomagnetic field intensity around 1.3 billion years ago may not be related to the birth of the inner core.

  10. Reduced aggregation and sedimentation of zero-valent iron nanoparticles in the presence of guar gum.

    PubMed

    Tiraferri, Alberto; Chen, Kai Loon; Sethi, Rajandrea; Elimelech, Menachem

    2008-08-01

    Injection of nanoscale zero-valent iron (NZVI) is potentially a promising technology for remediation of contaminated groundwaters. However, the efficiency of this process is significantly hindered by the rapid aggregation of the iron nanoparticles. The aim of this study was to enhance the colloidal stability of the nanoparticles through the addition of the "green" polymer guar gum. We evaluated the properties of guar gum and its influence on the surface properties, particle size, aggregation, and sedimentation of iron nanoparticles. Commercial iron nanoparticles were dispersed in guar gum solutions, and their aggregation and sedimentation behaviors were compared to those of bare iron nanoparticles and commercial nanoparticles modified with a biodegradable polymer (polyaspartate). High performance size exclusion chromatography, charge titration, and viscosity assessment showed that guar gum is a high molecular weight polymer which is nearly neutrally charged, rendering it suitable for steric stabilization of the iron nanoparticles. Electrophoretic mobility measurements demonstrated the ability of guar gum to adsorb on the nanoparticles, forming a slightly negatively charged layer. Dynamic light scattering experiments were conducted to estimate the particle size of the different nanoparticle suspensions and to determine the aggregation behavior at different ionic strengths. Guar gum effectively reduced the hydrodynamic radius of the bare nanoparticles from 500 nm to less than 200 nm and prevented aggregation of the nanoparticles even at very high salt concentrations (0.5 M NaCl and 3 mM CaCl(2)). Sedimentation profiles of the different nanoparticle suspensions confirmed the improved stability of the iron nanoparticles in the presence of guar gum. The results strongly suggest that guar gum can be used to effectively deliver stabilized zero-valent iron nanoparticles for remediation of contaminated groundwater aquifers.

  11. Chemical and Colloidal Stability of Carboxylated Core-Shell Magnetite Nanoparticles Designed for Biomedical Applications

    PubMed Central

    Szekeres, Márta; Tóth, Ildikó Y.; Illés, Erzsébet; Hajdú, Angéla; Zupkó, István; Farkas, Katalin; Oszlánczi, Gábor; Tiszlavicz, László; Tombácz, Etelka

    2013-01-01

    Despite the large efforts to prepare super paramagnetic iron oxide nanoparticles (MNPs) for biomedical applications, the number of FDA or EMA approved formulations is few. It is not known commonly that the approved formulations in many instances have already been withdrawn or discontinued by the producers; at present, hardly any approved formulations are produced and marketed. Literature survey reveals that there is a lack for a commonly accepted physicochemical practice in designing and qualifying formulations before they enter in vitro and in vivo biological testing. Such a standard procedure would exclude inadequate formulations from clinical trials thus improving their outcome. Here we present a straightforward route to assess eligibility of carboxylated MNPs for biomedical tests applied for a series of our core-shell products, i.e., citric acid, gallic acid, poly(acrylic acid) and poly(acrylic acid-co-maleic acid) coated MNPs. The discussion is based on physicochemical studies (carboxylate adsorption/desorption, FTIR-ATR, iron dissolution, zeta potential, particle size, coagulation kinetics and magnetization measurements) and involves in vitro and in vivo tests. Our procedure can serve as an example to construct adequate physico-chemical selection strategies for preparation of other types of core-shell nanoparticles as well. PMID:23857054

  12. Iron-rich Oxides at the Core-mantle Boundary

    NASA Astrophysics Data System (ADS)

    Wicks, J. K.; Jackson, J. M.; Sturhahn, W.; Bower, D. J.; Zhuravlev, K. K.; Prakapenka, V.

    2013-12-01

    Seismic observations near the base of the core-mantle boundary (CMB) have detected 5-20 km thick patches in which the seismic wave velocities are reduced by up to 30%. These ultra-low velocity zones (ULVZs) have been interpreted as aggregates of partially molten material (e.g. Williams and Garnero 1996, Hernlund and Jellinek, 2010) or as solid, iron-enriched residues (e.g. Knittle and Jeanloz, 1991; Mao et al., 2006; Wicks et al., 2010), typically based on proposed sources of velocity reduction. The stabilities of these structure types have been explored through dynamic models that have assembled a relationship between ULVZ stability and density (Hernlund and Tackley, 2007; Bower et al., 2010). Now, to constrain the chemistry and mineralogy of ULVZs, more information is needed on the relationship between density and sound velocity of candidate phases. We present the pressure-volume-temperature equation of state of (Mg0.06 57Fe0.94)O determined up to pressures of 120 GPa and temperatures of 2000 K. Volume was measured with X-ray diffraction at beamline 13-ID-D of the Advanced Photon Source (APS), where high pressures and temperatures are achieved in a diamond anvil cell with in-situ laser heating. Sample assemblies were prepared using dehydrated NaCl as an insulator and neon as a pressure transmitting medium. We present results with and without iron as a buffer and thermal pressure gauge. We have also determined the room temperature Debye velocity (VD) of (Mg0.06 57Fe0.94)O using nuclear resonant inelastic x-ray scattering and in-situ X-ray diffraction, up to 80 GPa at 3-ID-B of the APS. The effect of the electronic environment of the iron sites on the velocities was tracked in-situ using synchrotron Moessbauer spectroscopy. Using our measured equation of state, the seismically relevant compressional (VP) and shear (VS) wave velocities were calculated from the Debye velocities. We combine these studies with a simple mixing model to predict the properties of a solid

  13. Conquering the Dark Side: Colloidal Iron Oxide Nanoparticles

    PubMed Central

    Senpan, Angana; Caruthers, Shelton D.; Rhee, Ilsu; Mauro, Nicholas A.; Pan, Dipanjan; Hu, Grace; Scott, Michael J.; Fuhrhop, Ralph W.; Gaffney, Patrick J.; Wickline, Samuel A.; Lanza, Gregory M.

    2009-01-01

    Nanomedicine approaches to atherosclerotic disease will have significant impact on the practice and outcomes of cardiovascular medicine. Iron oxide nanoparticles have been extensively used for nontargeted and targeted imaging applications based upon highly sensitive T2* imaging properties, which typically result in negative contrast effects that can only be imaged 24 or more hours after systemic administration due to persistent blood pool interference. Although recent advances involving MR pulse sequences have converted these dark contrast voxels into bright ones, the marked delays in imaging from persistent magnetic background interference and prominent dipole blooming effects of the magnetic susceptibility remain barriers to overcome. We report a T1-weighted (T1w) theranostic colloidal iron oxide nanoparticle platform, CION, which is achieved by entrapping oleate-coated magnetite particles within a cross-linked phospholipid nanoemulsion. Contrary to expectations, this formulation decreased T2 effects thus allowing positive T1w contrast detection down to low nanomolar concentrations. CION, a vascular constrained nanoplatform administered in vivo permitted T1w molecular imaging 1 hour after treatment without blood pool interference, although some T2 shortening effects on blood, induced by the superparamagnetic particles persisted. Moreover, CION was shown to encapsulate antiangiogenic drugs, like fumagillin, and retained them under prolonged dissolution, suggesting significant theranostic functionality. Overall, CION is a platform technology, developed with generally recognized as safe components, that overcomes the temporal and spatial imaging challenges associated with current iron oxide nanoparticle T2 imaging agents, and which has theranostic potential in vascular diseases for detecting unstable ruptured plaque or treating atherosclerotic angiogenesis. PMID:19908850

  14. Binding studies of creatinine and urea on iron-nanoparticle.

    PubMed

    Banerji, Biswadip; Pramanik, Sumit Kumar

    2015-01-01

    Kidney diseases are complicated and can be fatal. Dialysis and transplantation are the only survival solutions to the patients suffering from kidney failures. Both hemodialysis and peritoneal dialysis are risky, due to the possibility of infection and these are expensive and time consuming. The development of simple and reliable technique for the clearance of creatinine and urea from the body is an important part of biotechnology. We have synthesized an iron nanoparticle (INP) and studied its binding with creatinine and urea. The DLS, TEM, AFM, FT-IR and Powder-XRD studies demonstrate strong binding of creatinine and urea to the nanoparticles. This finding may be helpful if it is used in the dialysis technologies. The proposed method may substantially decrease dialysis time and improve its quality in terms of urea and creatinine clearances.

  15. Synthesis of triangular Au core-Ag shell nanoparticles

    SciTech Connect

    Rai, Akhilesh; Chaudhary, Minakshi; Ahmad, Absar; Bhargava, Suresh; Sastry, Murali . E-mail: msastry@tatachemicals.com

    2007-07-03

    In this paper, we demonstrate a simple and reproducible method for the synthesis of triangular Au core-Ag shell nanoparticles. The triangular gold core is obtained by the reduction of gold ions by lemongrass extract. Utilizing the negative charge on the gold nanotriangles, silver ions are bound to their surface and thereafter reduced by ascorbic acid under alkaline conditions. The thickness of the silver shell may be modulated by varying the pH of the reaction medium. The formation of the Au core-Ag shell triangular nanostructures has been followed by UV-vis-NIR Spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy (TEM) and atomic force microscopy (AFM) measurements. The sharp vertices of the triangles coupled with the core-shell structure is expected to have potential for application in surface enhanced Raman spectroscopy and in the sensitive detection of biomolecules.

  16. Recovery of Iron/Iron Oxide Nanoparticles from Solution: Comparison of Methods and their Effects

    SciTech Connect

    Nurmi, James; Sarathy, Vaishnavi; Tratnyek, P. G.; Baer, Donald R.; Amonette, James E.; Karkamkar, Abhijeet J.

    2011-05-15

    Most methods currently being used to recover Fe0-core/oxide-shell nanoparticles from solutions (including the solvents they are synthesized or stored in) are potentially problematic because they may alter the particle composition (e.g., depositing salts formed from solutes) or leave the particles prone to transformations during subsequent storage and handling (e.g., due to residual moisture). In this study, several methods for recovery of nanoparticles from aqueous solution were studied to determine how they affect the structure and reactivity of the recovered materials. Simple washing of the nanoparticles during vacuum filtration (i.e., “flash drying”) can leave up to ~17 weight percent residual moisture. Modeling calculations suggest this moisture is mostly capillary or matric water held between particles and particle aggregates, which can be removed by drying for short periods at relative vapor pressures below 0.9. Flash drying followed by vacuum drying, all under N2, leaves no detectable residue from precipitation of solutes (detectable by X-ray photoelectron spectroscopy, XPS), no significant changes in overall particle composition or structure (determined by transmission electron microscopy, TEM), and negligible residual moisture (by thermogravimetric analysis, TGA). While this improved flash-drying protocol may be the preferred method for recovering nanoparticles for many purposes, we found that Fe0-core/oxide-shell nanoparticles still exhibit gradual aging during storage when characterized electrochemically with voltammetry.

  17. Genotoxicity of Superparamagnetic Iron Oxide Nanoparticles in Granulosa Cells.

    PubMed

    Pöttler, Marina; Staicu, Andreas; Zaloga, Jan; Unterweger, Harald; Weigel, Bianca; Schreiber, Eveline; Hofmann, Simone; Wiest, Irmi; Jeschke, Udo; Alexiou, Christoph; Janko, Christina

    2015-01-01

    Nanoparticles that are aimed at targeting cancer cells, but sparing healthy tissue provide an attractive platform of implementation for hyperthermia or as carriers of chemotherapeutics. According to the literature, diverse effects of nanoparticles relating to mammalian reproductive tissue are described. To address the impact of nanoparticles on cyto- and genotoxicity concerning the reproductive system, we examined the effect of superparamagnetic iron oxide nanoparticles (SPIONs) on granulosa cells, which are very important for ovarian function and female fertility. Human granulosa cells (HLG-5) were treated with SPIONs, either coated with lauric acid (SEONLA) only, or additionally with a protein corona of bovine serum albumin (BSA; SEON(LA-BSA)), or with dextran (SEON(DEX)). Both micronuclei testing and the detection of γH2A.X revealed no genotoxic effects of SEON(LA-BSA), SEON(DEX) or SEON(LA). Thus, it was demonstrated that different coatings of SPIONs improve biocompatibility, especially in terms of genotoxicity towards cells of the reproductive system. PMID:26540051

  18. Biosynthesis of stable iron oxide nanoparticles in aqueous extracts of Hordeum vulgare and Rumex acetosa plants.

    PubMed

    Makarov, Valentin V; Makarova, Svetlana S; Love, Andrew J; Sinitsyna, Olga V; Dudnik, Anna O; Yaminsky, Igor V; Taliansky, Michael E; Kalinina, Natalia O

    2014-05-27

    We report the synthesis and characterization of amorphous iron oxide nanoparticles from iron salts in aqueous extracts of monocotyledonous (Hordeum vulgare) and dicotyledonous (Rumex acetosa) plants. The nanoparticles were characterized by TEM, absorbance spectroscopy, SAED, EELS, XPS, and DLS methods and were shown to contain mainly iron oxide and iron oxohydroxide. H. vulgare extracts produced amorphous iron oxide nanoparticles with diameters of up to 30 nm. These iron nanoparticles are intrinsically unstable and prone to aggregation; however, we rendered them stable in the long term by addition of 40 mM citrate buffer pH 3.0. In contrast, amorphous iron oxide nanoparticles (diameters of 10-40 nm) produced using R. acetosa extracts are highly stable. The total protein content and antioxidant capacity are similar for both extracts, but pH values differ (H. vulgare pH 5.8 vs R. acetosa pH 3.7). We suggest that the presence of organic acids (such oxalic or citric acids) plays an important role in the stabilization of iron nanoparticles, and that plants containing such constituents may be more efficacious for the green synthesis of iron nanoparticles.

  19. Core - shell upconversion nanoparticle - semiconductor heterostructures for photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Dou, Qing Qing; Rengaramchandran, Adith; Selvan, Subramanian Tamil; Paulmurugan, Ramasamy; Zhang, Yong

    2015-02-01

    Core-shell nanoparticles (CSNPs) with diverse chemical compositions have been attracting greater attention in recent years. However, it has been a challenge to develop CSNPs with different crystal structures due to the lattice mismatch of the nanocrystals. Here we report a rational design of core-shell heterostructure consisting of NaYF4:Yb,Tm upconversion nanoparticle (UCN) as the core and ZnO semiconductor as the shell for potential application in photodynamic therapy (PDT). The core-shell architecture (confirmed by TEM and STEM) enables for improving the loading efficiency of photosensitizer (ZnO) as the semiconductor is directly coated on the UCN core. Importantly, UCN acts as a transducer to sensitize ZnO and trigger the generation of cytotoxic reactive oxygen species (ROS) to induce cancer cell death. We also present a firefly luciferase (FLuc) reporter gene based molecular biosensor (ARE-FLuc) to measure the antioxidant signaling response activated in cells during the release of ROS in response to the exposure of CSNPs under 980 nm NIR light. The breast cancer cells (MDA-MB-231 and 4T1) exposed to CSNPs showed significant release of ROS as measured by aminophenyl fluorescein (APF) and ARE-FLuc luciferase assays, and ~45% cancer cell death as measured by MTT assay, when illuminated with 980 nm NIR light.

  20. Core-shell upconversion nanoparticle - semiconductor heterostructures for photodynamic therapy.

    PubMed

    Dou, Qing Qing; Rengaramchandran, Adith; Selvan, Subramanian Tamil; Paulmurugan, Ramasamy; Zhang, Yong

    2015-01-01

    Core-shell nanoparticles (CSNPs) with diverse chemical compositions have been attracting greater attention in recent years. However, it has been a challenge to develop CSNPs with different crystal structures due to the lattice mismatch of the nanocrystals. Here we report a rational design of core-shell heterostructure consisting of NaYF4:Yb,Tm upconversion nanoparticle (UCN) as the core and ZnO semiconductor as the shell for potential application in photodynamic therapy (PDT). The core-shell architecture (confirmed by TEM and STEM) enables for improving the loading efficiency of photosensitizer (ZnO) as the semiconductor is directly coated on the UCN core. Importantly, UCN acts as a transducer to sensitize ZnO and trigger the generation of cytotoxic reactive oxygen species (ROS) to induce cancer cell death. We also present a firefly luciferase (FLuc) reporter gene based molecular biosensor (ARE-FLuc) to measure the antioxidant signaling response activated in cells during the release of ROS in response to the exposure of CSNPs under 980 nm NIR light. The breast cancer cells (MDA-MB-231 and 4T1) exposed to CSNPs showed significant release of ROS as measured by aminophenyl fluorescein (APF) and ARE-FLuc luciferase assays, and ~45% cancer cell death as measured by MTT assay, when illuminated with 980 nm NIR light. PMID:25652742

  1. Synthesis, purification and assembly of gold and iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Qiu, Penghe

    , 6 & 7), nanoparticles were assembled into three different hierachical structures through both template-assisted and template-free approaches. In the template-assisted assembly, gold nanorods were aligned into ordered 1D linear pattern by using soft biological filamentous, namely bacteria flagella, as templates. Two different ways of assembling nanorods onto flagella were investigated. In another study, a highly commercialized polymer, polyvinylpyrrolidone (PVP), was discovered for the first time to be able to self-assemble into branched hollow fibers. Based on this discovery, two approaches (one through direct deposition of silica onto the PVP aggregate and the other through co-assembly of PVP covered gold nanoparticles with free PVP molecules) by which the self-assembly behavior of PVP could be exploited to template the formation of branched hollow inorganic fibers were demonstrated. In the template-free assembly, a general method for assembling nanoparticle into clusters (NPCs) in an oil-in-water emulsion system was investigated. Detailed studies on the mechanism of formation of NPCs structure, optimized conditions, scalable production and surface chemistry manipulation were carried out. Besides, comparison of the properties of individual and clustered iron oxide nanoparticles was conducted. It was discovered that due to their collective properties, NPCs are more responsive to an external magnetic field and can potentially serve as better contrast enhancement agents than individually dispersed magnetic NPs in Magnetic Resonance Imaging (MRI).

  2. New surface radiolabeling schemes of super paramagnetic iron oxide nanoparticles (SPIONs) for biodistribution studies

    NASA Astrophysics Data System (ADS)

    Nallathamby, Prakash D.; Mortensen, Ninell P.; Palko, Heather A.; Malfatti, Mike; Smith, Catherine; Sonnett, James; Doktycz, Mitchel J.; Gu, Baohua; Roeder, Ryan K.; Wang, Wei; Retterer, Scott T.

    2015-04-01

    Nanomaterial based drug delivery systems allow for the independent tuning of the surface chemical and physical properties that affect their biodistribution in vivo and the therapeutic payloads that they are intended to deliver. Additionally, the added therapeutic and diagnostic value of their inherent material properties often provides extra functionality. Iron based nanomaterials with their magnetic properties and easily tailorable surface chemistry are of particular interest as model systems. In this study the core radius of the iron oxide nanoparticles (NPs) was 14.08 +/- 3.92 nm while the hydrodynamic radius of the NPs, as determined by Dynamic Light Scattering (DLS), was between 90-110 nm. In this study, different approaches were explored to create radiolabeled NPs that are stable in solution. The NPs were functionalized with polycarboxylate or polyamine surface functional groups. Polycarboxylate functionalized NPs had a zeta potential of -35 mV and polyamine functionalized NPs had a zeta potential of +40 mV. The polycarboxylate functionalized NPs were chosen for in vivo biodistribution studies and hence were radiolabeled with 14C, with a final activity of 0.097 nCi mg-1 of NPs. In chronic studies, the biodistribution profile is tracked using low level radiolabeled proxies of the nanoparticles of interest. Conventionally, these radiolabeled proxies are chemically similar but not chemically identical to the non-radiolabeled NPs of interest. This study is novel as different approaches were explored to create radiolabeled NPs that are stable, possess a hydrodynamic radius of <100 nm and most importantly they exhibit an identical surface chemical functionality as their non-radiolabeled counterparts. Identical chemical functionality of the radiolabeled probes to the non-radiolabeled probes was an important consideration to generate statistically similar biodistribution data sets using multiple imaging and detection techniques. The radiolabeling approach described

  3. Shape control of the magnetic iron oxide nanoparticles under different chain length of reducing agents

    SciTech Connect

    Ngoi, Kuan Hoon; Chia, Chin-Hua Zakaria, Sarani; Chiu, Wee Siong

    2015-09-25

    We report on the effect of using reducing agents with different chain-length on the synthesis of iron oxide nanoparticles by thermal decomposition of iron (III) acetylacetonate in 1-octadecene. This modification allows us to control the shape of nanoparticles into spherical and cubic iron oxide nanoparticles. The highly monodisperse 14 nm spherical nanoparticles are obtained under 1,2-dodecanediol and average 14 nm edge-length cubic iron oxide nanoparticles are obtained under 1,2-tetradecanediol. The structural characterization such as transmission electron microscope (TEM) and X-ray diffraction (XRD) shows similar properties between two particles with different shapes. The vibrating sample magnetometer (VSM) shows no significant difference between spherical and cubic nanoparticles, which are 36 emu/g and 37 emu/g respectively and superparamagnetic in nature.

  4. The effect of coating on heat generation properties of Iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Yuan, Yuan

    Magnetic nanoparticles have attracted more and more attention for their potential application as heating agents in cancer hyperthermia. The effectiveness of cancer hyperthermia can be increased by using particles that have a higher heat generation rate, quantified by specific absorption rate (SAR), at a smaller applied field. In order to optimize the functionality of nanoparticles as heating agents, it is essential to have a comprehensive understanding of factors that may influence SAR including coating and aggregation. In all biomedical applications, the magnetic particles are coated with surfactants and polymers to enhance biocompatibility, prevent agglomeration and add functionality. Coatings may profoundly influence particles' clustering behavior and magnetic properties. Yet its effect on the heat generation rate of the nanoparticles has been scarcely investigated. In this context, a systematic investigation was carried out in this dissertation in order to understand the impact of the surface coating of magnetic nanoparticles on their heat generation rate. The study also includes investigation of normal nerve cell viability in presence of biofunctionalized magnetic nanoparticles with and without exposure to magnetic heating. Commercially available suspensions of iron oxide nanoparticles with a diameter of approximately 10 nm and different coatings relevant to biomedical applications such as aminosilane, carboxymethyl-dextran, protein A, biotin were extensively characterized. First of all, magnetic phase reduction of magnetite nanoparticles was examined by studying the discrepancy between the volume fraction of magnetic phase calculated from magnetization curve and the magnetic core concentration obtained from Tiron chelation test. The findings indicated that coatings might interact with the surface atoms of the magnetic core and form a magnetically disordered layer reducing the total amount of the magnetic phase. Secondly, the impact of coating and aggregation

  5. Superparamagnetic iron oxide nanoparticles with variable size and an iron oxidation state as prospective imaging agents.

    PubMed

    Kucheryavy, Pavel; He, Jibao; John, Vijay T; Maharjan, Pawan; Spinu, Leonard; Goloverda, Galina Z; Kolesnichenko, Vladimir L

    2013-01-15

    Magnetite nanoparticles in the size range of 3.2-7.5 nm were synthesized in high yields under variable reaction conditions using high-temperature hydrolysis of the precursor iron(II) and iron(III) alkoxides in diethylene glycol solution. The average sizes of the particles were adjusted by changing the reaction temperature and time and by using a sequential growth technique. To obtain γ-iron(III) oxide particles in the same range of sizes, magnetite particles were oxidized with dry oxygen in diethylene glycol at room temperature. The products were characterized by DLS, TEM, X-ray powder diffractometry, TGA, chemical analysis, and magnetic measurements. NMR r(1) and r(2) relaxivity measurements in water and diethylene glycol (for OH and CH(2) protons) have shown a decrease in the r(2)/r(1) ratio with the particle size reduction, which correlates with the results of magnetic measurements on magnetite nanoparticles. Saturation magnetization of the oxidized particles was found to be 20% lower than that for Fe(3)O(4) with the same particle size, but their r(1) relaxivities are similar. Because the oxidation of magnetite is spontaneous under ambient conditions, it was important to learn that the oxidation product has no disadvantages as compared to its precursor and therefore may be a better prospective imaging agent because of its chemical stability.

  6. Temperature-tunable iron oxide nanoparticles for remote-controlled drug release.

    PubMed

    Dani, Raj K; Schumann, Canan; Taratula, Olena; Taratula, Oleh

    2014-08-01

    Herein, we report the successful development of a novel nanosystem capable of an efficient delivery and temperature-triggered drug release specifically aimed at cancer. The water-soluble 130.1 ± 0.2 nm iron oxide nanoparticles (IONPs) were obtained via synthesis of a monodispersed iron oxide core stabilized with tetramethylammonium hydroxide pentahydrate (TMAOH), followed by coating with the thermoresponsive copolymer poly-(NIPAM-stat-AAm)-block-PEI (PNAP). The PNAP layer on the surface of the IONP undergoes reversible temperature-dependent structural changes from a swollen to a collapsed state resulting in the controlled release of anticancer drugs loaded in the delivery vehicle. We demonstrated that the phase transition temperature of the prepared copolymer can be precisely tuned to the desired value in the range of 36°C-44°C by changing the monomers ratio during the preparation of the nanoparticles. Evidence of modification of the IONPs with the thermoresponsive copolymer is proven by ATR-FTIR and a quantitative analysis of the polymeric and iron oxide content obtained by thermogravimetric analysis. When loaded with doxorubicin (DOX), the IONPs-PNAP revealed a triggered drug release at a temperature that is a few degrees higher than the phase transition temperature of a copolymer. Furthermore, an in vitro study demonstrated an efficient internalization of the nanoparticles into the cancer cells and showed that the drug-free IONPs-PNAP were nontoxic toward the cells. In contrast, sufficient therapeutic effect was observed for the DOX-loaded nanosystem as a function of temperature. Thus, the developed temperature-tunable IONPs-based delivery system showed high potential for remotely triggered drug delivery and the eradication of cancer cells. PMID:24821220

  7. Nanoparticle and Iron Chelators as a Potential Novel Alzheimer Therapy

    PubMed Central

    Liu, Gang; Men, Ping; Perry, George; Smith, Mark A.

    2010-01-01

    Current therapies for Alzheimer disease (AD) such as the acetylcholinesterase inhibitors and the latest NMDA receptor inhibitor, Namenda, provide moderate symptomatic delay at various stages of the disease, but do not arrest the disease progression or bring in meaningful remission. New approaches to the disease management are urgently needed. Although the etiology of AD is largely unknown, oxidative damage mediated by metals is likely a significant contributor since metals such as iron, aluminum, zinc, and copper are dysregulated and/or increased in AD brain tissue and create a pro-oxidative environment. This role of metal ion-induced free radical formation in AD makes chelation therapy an attractive means of dampening the oxidative stress burden in neurons. The chelator desferrioxamine, FDA approved for iron overload, has shown some benefit in AD, but like many chelators, it has a host of adverse effects and substantial obstacles for tissue-specific targeting. Other chelators are under development and have shown various strengths and weaknesses. Here, we propose a novel system of chelation therapy through the use of nanoparticles. Nanoparticles conjugated to chelators show unique ability to cross the blood–brain barrier (BBB), chelate metals, and exit through the BBB with their corresponding complexed metal ions. This method may provide a safer and more effective means of reducing the metal load in neural tissue, thus attenuating the harmful effects of oxidative damage and its sequelae. Experimental procedures are presented in this chapter. PMID:20013176

  8. Investigation on Sized-Regulated Iron Nanoparticles Prepared by Liquid Phase Plasma Reduction Process.

    PubMed

    Heon, Lee; Kim, Hwan-Gi; Kim, Byung Hoon; Yun, Je-Jung; Chung, Minchul; Ahn, Ho-Geun; Lee, Young-Seak; Jung, Sang-Chul

    2015-01-01

    The liquid-phase plasma reduction method has been applied to prepare iron nanoparticles from iron chloride solution using a bipolar pulsed electrical discharge system. The excited states of atomic iron, hydrogen, and oxygen as well as the molecular bands of hydroxyl radicals were detected in the emission spectra. The iron nanoclusters formed at the initial stage convert to dispersion of small iron nanoparticles, which then grows slowly to form anisotropic, tetragonal shape. The cationic surfactant of CTAB was shown to exhibit a large influence on the particle generation procedure. PMID:26328393

  9. Differentiated planetesimal impacts into a terrestrial magma ocean: Fate of the iron core

    NASA Astrophysics Data System (ADS)

    Kendall, Jordan D.; Melosh, H. J.

    2016-08-01

    The abundance of moderately siderophile elements ("iron-loving"; e.g. Co, Ni) in the Earth's mantle is 10 to 100 times larger than predicted by chemical equilibrium between silicate melt and iron at low pressure, but it does match expectation for equilibrium at high pressure and temperature. Recent studies of differentiated planetesimal impacts assume that planetesimal cores survive the impact intact as concentrated masses that passively settle from a zero initial velocity and undergo turbulent entrainment in a global magma ocean; under these conditions, cores greater than 10 km in diameter do not fully mix without a sufficiently deep magma ocean. We have performed hydrocode simulations that revise this assumption and yield a clearer picture of the impact process for differentiated planetesimals possessing iron cores with radius = 100 km that impact into magma oceans. The impact process strips away the silicate mantle of the planetesimal and then stretches the iron core, dispersing the liquid iron into a much larger volume of the underlying liquid silicate mantle. Lagrangian tracer particles track the initially intact iron core as the impact stretches and disperses the core. The final displacement distance of initially closest tracer pairs gives a metric of core stretching. The statistics of stretching imply mixing that separates the iron core into sheets, ligaments, and smaller fragments, on a scale of 10 km or less. The impact dispersed core fragments undergo further mixing through turbulent entrainment as the molten iron fragments rain through the magma ocean and settle deeper into the planet. Our results thus support the idea that iron in the cores of even large differentiated planetesimals can chemically equilibrate deep in a terrestrial magma ocean.

  10. Enhanced Verdet constant via gold coated iron oxide nanoparticles and via change in host medium

    NASA Astrophysics Data System (ADS)

    Dick, Nathan T.

    caused by surface plasmon resonance of the gold coating and magneto optic effect of the iron core of the nanoparticle.

  11. Iron oxide nanoparticles for magnetically assisted patterned coatings

    NASA Astrophysics Data System (ADS)

    Dodi, Gianina; Hritcu, Doina; Draganescu, Dan; Popa, Marcel I.

    2015-08-01

    Iron oxide nanoparticles able to magnetically assemble during the curing stage of a polymeric support to create micro-scale surface protuberances in a controlled manner were prepared and characterized. The bare Fe3O4 particles were obtained by two methods: co-precipitation from an aqueous solution containing Fe3+/Fe2+ ions with a molar ratio of 2:1 and partial oxidation of ferrous ions in alkaline conditions. The products were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and magnetization measurement. They were subsequently functionalized using oleic acid, sodium oleate, or non-ionic surfactant mixtures with various hydrophilic to lipophilic balance (HLB) values. Composite nanoparticle-polymer films prepared by spraying were deposited and cured by drying on glass slides under a static magnetic field in the range of 1.5-5.5 mT. Magnetic field generated surface roughness was evidenced by optical and scanning electron microscopy. The optimum hierarchical patterning was obtained with the nanoparticles produced by partial oxidation and functionalized with hydrophobic surfactants. Possible applications may include ice-phobic composite coatings.

  12. Biocompatible capped iron oxide nanoparticles for Vibrio cholerae detection

    NASA Astrophysics Data System (ADS)

    Sharma, Anshu; Baral, Dinesh; Rawat, Kamla; Solanki, Pratima R.; Bohidar, H. B.

    2015-05-01

    We report the studies relating to fabrication of an efficient immunosensor for Vibrio cholerae detection. Magnetite (iron oxide (Fe3O4)) nanoparticles (NPs) have been synthesized by the co-precipitation method and capped by citric acid (CA). These NPs were electrophoretically deposited onto indium-tin-oxide (ITO)-coated glass substrate and used for immobilization of monoclonal antibodies against Vibrio cholerae (Ab) and bovine serum albumin (BSA) for Vibrio cholerae detection using an electrochemical technique. The structural and morphological studies of Fe3O4 and CA-Fe3O4/ITO were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and dynamic light scattering (DLS) techniques. The average crystalline size of Fe3O4, CA-Fe3O4 nanoparticles obtained were about 29 ± 1 nm and 37 ± 1 nm, respectively. The hydrodynamic radius of the nanoparticles was found to be 77.35 nm (Fe3O4) and 189.51 nm (CA-Fe3O4) by DLS measurement. The results of electrochemical response studies of the fabricated BSA/Ab/CA-Fe2O3/ITO immunosensor exhibits a good detection range of 12.5-500 ng mL-1 with a low detection limit of 0.32 ng mL-1, sensitivity 0.03 Ω/ng ml-1 cm-2, and reproducibility more than 11 times.

  13. Biocompatible capped iron oxide nanoparticles for Vibrio cholerae detection.

    PubMed

    Sharma, Anshu; Baral, Dinesh; Rawat, Kamla; Solanki, Pratima R; Bohidar, H B

    2015-05-01

    We report the studies relating to fabrication of an efficient immunosensor for Vibrio cholerae detection. Magnetite (iron oxide (Fe(3)O(4))) nanoparticles (NPs) have been synthesized by the co-precipitation method and capped by citric acid (CA). These NPs were electrophoretically deposited onto indium-tin-oxide (ITO)-coated glass substrate and used for immobilization of monoclonal antibodies against Vibrio cholerae (Ab) and bovine serum albumin (BSA) for Vibrio cholerae detection using an electrochemical technique. The structural and morphological studies of Fe(3)O(4) and CA-Fe(3)O(4)/ITO were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and dynamic light scattering (DLS) techniques. The average crystalline size of Fe(3)O(4), CA-Fe(3)O(4) nanoparticles obtained were about 29 ± 1 nm and 37 ± 1 nm, respectively. The hydrodynamic radius of the nanoparticles was found to be 77.35 nm (Fe(3)O(4)) and 189.51 nm (CA-Fe(3)O(4)) by DLS measurement. The results of electrochemical response studies of the fabricated BSA/Ab/CA-Fe(2)O(3)/ITO immunosensor exhibits a good detection range of 12.5-500 ng mL(-1) with a low detection limit of 0.32 ng mL(-1), sensitivity 0.03 Ω/ng ml(-1) cm(-2), and reproducibility more than 11 times.

  14. Removal of Trichloroethylene and Heavy Metals by Zerovalent Iron Nanoparticles

    NASA Astrophysics Data System (ADS)

    Boparai, H. K.; O'Carroll, D. M.

    2009-05-01

    Heavy metals combined with chlorinated solvents are one class of mixed waste found at various hazardous waste sites in North America. Nano zerovalent iron (nZVI), an emerging technology, is being successfully used for treating chlorinated solvents and heavy metals independently, however comparatively little research has investigated the remediation of the wastes when they are present in the same mixture. The remediation of trichloroethylene (TCE)/heavy metal waste mixtures via nZVI has been investigated in the present study. Results suggest that some metals are reduced by nZVI to their zerovalent state and thus precipitate on nZVI particles. This improves the contaminant removal performance of nZVI by forming bimetallic iron nanoparticles. Other metals are directly precipitated or adsorbed on the nZVI particles in their original oxidation state and are rendered immobile. In some cases the presence of the heavy metals in the waste mixture enhanced the dechlorination of TCE while in other cases it did not. This study suggests that nano zerovalent iron particles can be effectively used for the remediation of mixed contamination of heavy metals and chlorinated solvents. Results have been supported by a variety of techniques including X-ray photoelectron spectroscopy (XPS) analysis.

  15. Macroscopic and microscopic biodistribution of intravenously administered iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Misra, Adwiteeya; Petryk, Alicia A.; Strawbridge, Rendall R.; Hoopes, P. Jack

    2015-03-01

    Iron oxide nanoparticles (IONP) are being developed for use as a cancer treatment. They have demonstrated efficacy when used either as a monotherapy or in conjunction with conventional chemotherapy and radiation. The success of IONP as a therapeutic tool depends on the delivery of a safe and controlled cytotoxic thermal dose to tumor tissue following activation with an alternating magnetic field (AMF). Prior to clinical approval, knowledge of IONP toxicity, biodistribution and physiological clearance is essential. This preliminary time-course study determines the acute toxicity and biodistribution of 110 nm dextran-coated IONP (iron) in mice, 7 days post systemic, at doses of 0.4, 0.6, and 1.0 mg Fe/ g mouse bodyweight. Acute toxicity, manifested as changes in the behavior of mice, was only observed temporarily at 1.0 mg Fe/ g mouse bodyweight, the highest dose administered. Regardless of dose, mass spectrometry and histological analysis demonstrated over 3 mg Fe/g tissue in organs within the reticuloendotheilial system (i.e. liver, spleen, and lymph nodes). Other organs (brain, heart, lungs, and kidney) had less than 0.5 mg Fe/g tissue with iron predominantly confined to the organ vasculature.

  16. Differential proteomics analysis of the surface heterogeneity of dextran iron oxide nanoparticles and the implications for their in vivo clearance.

    PubMed

    Simberg, Dmitri; Park, Ji-Ho; Karmali, Priya P; Zhang, Wan-Ming; Merkulov, Sergei; McCrae, Keith; Bhatia, Sangeeta N; Sailor, Michael; Ruoslahti, Erkki

    2009-08-01

    In order to understand the role of plasma proteins in the rapid liver clearance of dextran-coated superparamagnetic iron oxide (SPIO) in vivo, we analyzed the full repertoire of SPIO-binding blood proteins using novel two-dimensional differential mass spectrometry approach. The identified proteins showed specificity for surface domains of the nanoparticles: mannan-binding lectins bound to the dextran coating, histidine-rich glycoprotein and kininogen bound to the iron oxide part, and the complement lectin and contact clotting factors were secondary binders. Nanoparticle clearance studies in knockout mice suggested that these proteins, as well as several previously identified opsonins, do not play a significant role in the SPIO clearance. However, both the dextran coat and the iron oxide core remained accessible to specific probes after incubation of SPIO in plasma, suggesting that the nanoparticle surface could be available for recognition by macrophages, regardless of protein coating. These data provide guidance to rational design of bioinert, long-circulating nanoparticles.

  17. Magnetic hyperthermia efficiency and (1)H-NMR relaxation properties of iron oxide/paclitaxel-loaded PLGA nanoparticles.

    PubMed

    Ruggiero, Maria R; Crich, Simonetta Geninatti; Sieni, Elisabetta; Sgarbossa, Paolo; Forzan, Michele; Cavallari, Eleonora; Stefania, Rachele; Dughiero, Fabrizio; Aime, Silvio

    2016-07-15

    Magnetic iron oxide nanoparticles (Fe-NPs) can be exploited in biomedicine as agents for magnetic fluid hyperthermia (MFH) treatments and as contrast enhancers in magnetic resonance imaging. New, oleate-covered, iron oxide particles have been prepared either by co-precipitation or thermal decomposition methods and incorporated into poly(lactic-co-glycolic acid) nanoparticles (PLGA-Fe-NPs) to improve their biocompatibility and in vivo stability. Moreover, the PLGA-Fe-NPs have been loaded with paclitaxel to pursue an MFH-triggered drug release. Remarkably, it has been found that the nanoparticle formulations are characterized by peculiar (1)H nuclear magnetic relaxation dispersion (NMRD) profiles that directly correlate with their heating potential when exposed to an alternating magnetic field. By prolonging the magnetic field exposure to 30 min, a significant drug release was observed for PLGA-Fe-NPs in the case of the larger-sized magnetic nanoparticles. Furthermore, the immobilization of lipophilic Fe-NPs in PLGA-NPs also made it possible to maintain Néel relaxation as the dominant relaxation contribution in the presence of large iron oxide cores (diameters of 15-20 nm), with the advantage of preserving their efficiency when they are entrapped in the intracellular environment. The results reported herein show that NMRD profiles are a useful tool for anticipating the heating capabilities of Fe-NPs designed for MFH applications. PMID:27265726

  18. Magnetic hyperthermia efficiency and 1H-NMR relaxation properties of iron oxide/paclitaxel-loaded PLGA nanoparticles

    NASA Astrophysics Data System (ADS)

    Ruggiero, Maria R.; Geninatti Crich, Simonetta; Sieni, Elisabetta; Sgarbossa, Paolo; Forzan, Michele; Cavallari, Eleonora; Stefania, Rachele; Dughiero, Fabrizio; Aime, Silvio

    2016-07-01

    Magnetic iron oxide nanoparticles (Fe-NPs) can be exploited in biomedicine as agents for magnetic fluid hyperthermia (MFH) treatments and as contrast enhancers in magnetic resonance imaging. New, oleate-covered, iron oxide particles have been prepared either by co-precipitation or thermal decomposition methods and incorporated into poly(lactic-co-glycolic acid) nanoparticles (PLGA-Fe-NPs) to improve their biocompatibility and in vivo stability. Moreover, the PLGA-Fe-NPs have been loaded with paclitaxel to pursue an MFH-triggered drug release. Remarkably, it has been found that the nanoparticle formulations are characterized by peculiar 1H nuclear magnetic relaxation dispersion (NMRD) profiles that directly correlate with their heating potential when exposed to an alternating magnetic field. By prolonging the magnetic field exposure to 30 min, a significant drug release was observed for PLGA-Fe-NPs in the case of the larger-sized magnetic nanoparticles. Furthermore, the immobilization of lipophilic Fe-NPs in PLGA-NPs also made it possible to maintain Néel relaxation as the dominant relaxation contribution in the presence of large iron oxide cores (diameters of 15-20 nm), with the advantage of preserving their efficiency when they are entrapped in the intracellular environment. The results reported herein show that NMRD profiles are a useful tool for anticipating the heating capabilities of Fe-NPs designed for MFH applications.

  19. Magnetic hyperthermia efficiency and 1H-NMR relaxation properties of iron oxide/paclitaxel-loaded PLGA nanoparticles

    NASA Astrophysics Data System (ADS)

    Ruggiero, Maria R.; Geninatti Crich, Simonetta; Sieni, Elisabetta; Sgarbossa, Paolo; Forzan, Michele; Cavallari, Eleonora; Stefania, Rachele; Dughiero, Fabrizio; Aime, Silvio

    2016-07-01

    Magnetic iron oxide nanoparticles (Fe-NPs) can be exploited in biomedicine as agents for magnetic fluid hyperthermia (MFH) treatments and as contrast enhancers in magnetic resonance imaging. New, oleate-covered, iron oxide particles have been prepared either by co-precipitation or thermal decomposition methods and incorporated into poly(lactic-co-glycolic acid) nanoparticles (PLGA-Fe-NPs) to improve their biocompatibility and in vivo stability. Moreover, the PLGA-Fe-NPs have been loaded with paclitaxel to pursue an MFH-triggered drug release. Remarkably, it has been found that the nanoparticle formulations are characterized by peculiar 1H nuclear magnetic relaxation dispersion (NMRD) profiles that directly correlate with their heating potential when exposed to an alternating magnetic field. By prolonging the magnetic field exposure to 30 min, a significant drug release was observed for PLGA-Fe-NPs in the case of the larger-sized magnetic nanoparticles. Furthermore, the immobilization of lipophilic Fe-NPs in PLGA-NPs also made it possible to maintain Néel relaxation as the dominant relaxation contribution in the presence of large iron oxide cores (diameters of 15–20 nm), with the advantage of preserving their efficiency when they are entrapped in the intracellular environment. The results reported herein show that NMRD profiles are a useful tool for anticipating the heating capabilities of Fe-NPs designed for MFH applications.

  20. Supramolecular core-shell nanoparticles for photoconductive device applications

    NASA Astrophysics Data System (ADS)

    Cheng, Chih-Chia; Chen, Jem-Kun; Shieh, Yeong-Tarng; Lee, Duu-Jong

    2016-08-01

    We report a breakthrough discovery involving supramolecular-based strategies to construct novel core-shell heterojunction nanoparticles with hydrophilic adenine-functionalized polythiophene (PAT) as the core and hydrophobic phenyl-C61-butyric acid methyl ester (PCBM) as the shell, which enables the conception of new functional supramolecular assemblies for constructing functional nanomaterials for applications in optoelectronic devices. The generated nanoparticles exhibit uniform spherical shape, well-controlled tuning of particle size with narrow size distributions, and excellent electrochemical stability in solution and the solid state owing to highly efficient energy transfer from PAT to PCBM. When the PAT/PCBM nanoparticles were fabricated into a photoconducting layer in an electronic device, the resulting device showed excellent electric conduction characteristics, including an electrically-tunable voltage-controlled switch, and high short-circuit current and open-circuit voltage. These observations demonstrate how the self-assembly of PAT/PCBM into specific nanostructures may help to promote efficient charge generation and transport processes, suggesting potential for a wide variety of applications as a promising candidate material for bulk heterojunction polymer devices.

  1. Supramolecular core-shell nanoparticles for photoconductive device applications.

    PubMed

    Cheng, Chih-Chia; Chen, Jem-Kun; Shieh, Yeong-Tarng; Lee, Duu-Jong

    2016-08-12

    We report a breakthrough discovery involving supramolecular-based strategies to construct novel core-shell heterojunction nanoparticles with hydrophilic adenine-functionalized polythiophene (PAT) as the core and hydrophobic phenyl-C61-butyric acid methyl ester (PCBM) as the shell, which enables the conception of new functional supramolecular assemblies for constructing functional nanomaterials for applications in optoelectronic devices. The generated nanoparticles exhibit uniform spherical shape, well-controlled tuning of particle size with narrow size distributions, and excellent electrochemical stability in solution and the solid state owing to highly efficient energy transfer from PAT to PCBM. When the PAT/PCBM nanoparticles were fabricated into a photoconducting layer in an electronic device, the resulting device showed excellent electric conduction characteristics, including an electrically-tunable voltage-controlled switch, and high short-circuit current and open-circuit voltage. These observations demonstrate how the self-assembly of PAT/PCBM into specific nanostructures may help to promote efficient charge generation and transport processes, suggesting potential for a wide variety of applications as a promising candidate material for bulk heterojunction polymer devices. PMID:27353003

  2. Effects of engineered iron nanoparticles on the bryophyte, Physcomitrella patens (Hedw.) Bruch & Schimp, after foliar exposure.

    PubMed

    Canivet, L; Dubot, P; Garçon, G; Denayer, F-O

    2015-03-01

    The effects of iron nanoparticles on bryophytes (Physcomitrella patens) were studied following foliar exposure. We used iron nanoparticles (Fe-NP) representative of industrial emissions from the metallurgical industries. After a characterization of iron nanoparticles and the validation of nanoparticle internalization in cells, the effects (cytotoxicity, oxidative stress, lipid peroxidation of membrane) of iron nanoparticles were determined through the axenic culturing of Physcomitrella patens exposed at five different concentrations (5 ng, 50 ng, 500 ng, 5 µg and 50 µg per plant). Following exposure, the plant health, measured as ATP concentrations, was not impacted. Moreover, we studied oxidative stress in three ways: through the measure of reactive oxygen species (ROS) production, through malondialdehyde (MDA) production and also through glutathione regulation. At concentrations tested over a short period, the level of ROS, MDA and glutathione were not significantly disturbed.

  3. Toxicity of zero-valent iron nanoparticles to a trichloroethylene-degrading groundwater microbial community.

    PubMed

    Zabetakis, Kara M; Niño de Guzmán, Gabriela T; Torrents, Alba; Yarwood, Stephanie

    2015-01-01

    The microbiological impact of zero-valent iron used in the remediation of groundwater was investigated by exposing a trichloroethylene-degrading anaerobic microbial community to two types of iron nanoparticles. Changes in total bacterial and archaeal population numbers were analyzed using qPCR and were compared to results from a blank and negative control to assess for microbial toxicity. Additionally, the results were compared to those of samples exposed to silver nanoparticles and iron filings in an attempt to discern the source of toxicity. Statistical analysis revealed that the three different iron treatments were equally toxic to the total bacteria and archaea populations, as compared with the controls. Conversely, the silver nanoparticles had a limited statistical impact when compared to the controls and increased the microbial populations in some instances. Therefore, the findings suggest that zero-valent iron toxicity does not result from a unique nanoparticle-based effect. PMID:26030685

  4. Toxicity of zero-valent iron nanoparticles to a trichloroethylene-degrading groundwater microbial community.

    PubMed

    Zabetakis, Kara M; Niño de Guzmán, Gabriela T; Torrents, Alba; Yarwood, Stephanie

    2015-01-01

    The microbiological impact of zero-valent iron used in the remediation of groundwater was investigated by exposing a trichloroethylene-degrading anaerobic microbial community to two types of iron nanoparticles. Changes in total bacterial and archaeal population numbers were analyzed using qPCR and were compared to results from a blank and negative control to assess for microbial toxicity. Additionally, the results were compared to those of samples exposed to silver nanoparticles and iron filings in an attempt to discern the source of toxicity. Statistical analysis revealed that the three different iron treatments were equally toxic to the total bacteria and archaea populations, as compared with the controls. Conversely, the silver nanoparticles had a limited statistical impact when compared to the controls and increased the microbial populations in some instances. Therefore, the findings suggest that zero-valent iron toxicity does not result from a unique nanoparticle-based effect.

  5. Core-shell biopolymer nanoparticle delivery systems: synthesis and characterization of curcumin fortified zein-pectin nanoparticles.

    PubMed

    Hu, Kun; Huang, Xiaoxia; Gao, Yongqing; Huang, Xulin; Xiao, Hang; McClements, David Julian

    2015-09-01

    Biopolymer core-shell nanoparticles were fabricated using a hydrophobic protein (zein) as the core and a hydrophilic polysaccharide (pectin) as the shell. Particles were prepared by coating cationic zein nanoparticles with anionic pectin molecules using electrostatic deposition (pH 4). The core-shell nanoparticles were fortified with curcumin (a hydrophobic bioactive molecule) at a high loading efficiency (>86%). The resulting nanoparticles were spherical, relatively small (diameter ≈ 250 nm), and had a narrow size distribution (polydispersity index ≈ 0.24). The encapsulated curcumin was in an amorphous (rather than crystalline form) as detected by differential scanning calorimetry (DSC). Fourier transform infrared (FTIR) and Raman spectra indicated that the encapsulated curcumin interacted with zein mainly through hydrophobic interactions. The nanoparticles were converted into a powdered form that had good water-dispersibility. These core-shell biopolymer nanoparticles could be useful for incorporating curcumin into functional foods and beverages, as well as dietary supplements and pharmaceutical products.

  6. Iron oxide nanoparticles induce Pseudomonas aeruginosa growth, induce biofilm formation, and inhibit antimicrobial peptide function.

    PubMed

    Borcherding, Jennifer; Baltrusaitis, Jonas; Chen, Haihan; Stebounova, Larissa; Wu, Chia-Ming; Rubasinghege, Gayan; Mudunkotuwa, Imali A; Caraballo, Juan Carlos; Zabner, Joseph; Grassian, Vicki H; Comellas, Alejandro P

    2014-04-01

    Given the increased use of iron-containing nanoparticles in a number of applications, it is important to understand any effects that iron-containing nanoparticles can have on the environment and human health. Since iron concentrations are extremely low in body fluids, there is potential that iron-containing nanoparticles may influence the ability of bacteria to scavenge iron for growth, affect virulence and inhibit antimicrobial peptide (AMP) function. In this study, Pseudomonas aeruginosa (PA01) and AMPs were exposed to iron oxide nanoparticles, hematite (α-Fe2O3), of different sizes ranging from 2 to 540 nm (2 ± 1, 43 ± 6, 85 ± 25 and 540 ± 90 nm) in diameter. Here we show that the greatest effect on bacterial growth, biofilm formation, and AMP function impairment is found when exposed to the smallest particles. These results are attributed in large part to enhanced dissolution observed for the smallest particles and an increase in the amount of bioavailable iron. Furthermore, AMP function can be additionally impaired by adsorption onto nanoparticle surfaces. In particular, lysozyme readily adsorbs onto the nanoparticle surface which can lead to loss of peptide activity. Thus, this current study shows that co-exposure of nanoparticles and known pathogens can impact host innate immunity. Therefore, it is important that future studies be designed to further understand these types of impacts. PMID:25221673

  7. Morphology and Oxide Shell Structure of Iron Nanoparticles Grown by Sputter-Gas-Aggregation

    SciTech Connect

    Wang, Chong M.; Baer, Donald R.; Amonette, James E.; Engelhard, Mark H.; Qiang, You; Antony, Jiji

    2007-06-27

    Much recent research effort has been made on the synthesis, characterization, and property evaluation of core-shell structured Fe nanoparticles. Fundamental properties of these particles depend on both their external crystal faceting planes and the nature of a protective oxide layer. In this paper, the crystal faceting planes and oxide coating structures of core-shell structured iron/iron oxide nanoparticles synthesized by a sputter-gas-aggregation process were studied using transmission electron microscopy (TEM), electron diffraction and Wulff shape construction. The particles grown by this process and deposited on a support at room temperature process have been compared with particles grown and deposited at high temperature as reported in literature. Most synthesis processes produce round particles for particles less than 20 nm in diameter. For larger particles crystallographic facets are observed. It has been found that the Fe nanoparticles formed at RT are invariantly faceted on the {100} lattice planes and truncated by the {110} planes at different degrees. Substantial fraction of particles are confined only by the 6 {100} planes (not truncated by the {110} planes), this contrasts with the Fe particles formed at high temperature (HT) for which a predominance of {110} planes has been reported. Furthermore, at RT no particle was identified to be only confined by the 12 {110} planes which is relatively common for the particles formed at HT. The Fe cubes defined by the 6 {100} planes show a characteristic inward relaxation along the <100> and <110> directions and the reason for this behavior is not fully understood. The oxide shell on the Fe {100} plane maintains an orientation relationship: Fe(001)//Fe3O4(001) and Fe[100]//Fe3O4[110], which is same as the oxide formed on a bulk Fe(001) through thermal oxidation. Orientation of the oxide that forms on the Fe{110} facets differs from that on Fe{001}, therefore, properties of core-shell structured Fe nanoparticle

  8. Exchange bias phenomenology and models of core/shell nanoparticles.

    PubMed

    Iglesias, Oscar; Labarta, Amílcar; Batlle, Xavier

    2008-06-01

    Some of the main experimental observations related to the occurrence of exchange bias in magnetic systems are reviewed, focusing the attention on the peculiar phenomenology associated to nanoparticles with core/shell structure as compared to thin film bilayers. The main open questions posed by the experimental observations are presented and contrasted to existing theories and models for exchange bias formulated up to date. We also present results of simulations based on a simple model of a core/shell nanoparticle in which the values of microscopic parameters such as anisotropy and exchange constants can be tuned in the core, shell and at the interfacial regions, offering new insight on the microscopic origin of the experimental phenomenology. A detailed study of the magnetic order of the interfacial spins shows compelling evidence that most of the experimentally observed effects can be qualitatively accounted within the context of this model and allows also to quantify the magnitude of the loop shifts in striking agreement with the macroscopic observed values.

  9. Influence of carbon chain length on the synthesis and yield of fatty amine-coated iron-platinum nanoparticles

    NASA Astrophysics Data System (ADS)

    Taylor, Robert M.; Monson, Todd C.; Gullapalli, Rama R.

    2014-06-01

    Iron oxide nanoparticles are among the most widely used and characterized magnetic nanoparticles. However, metal alloys such as superparamagnetic iron-platinum particles (SIPPs), which have better magnetic properties, are receiving increased attention. Scalable techniques to routinely synthesize SIPPs in bulk need further study. Here, we focus on the role played by the fatty amine ligand in the formation of the bimetallic FePt nanocrystal. More specifically, we compare the effect of varying lengths of fatty amine ligands on the shape, structure, uniformity, composition, and magnetic properties of the SIPPs. We synthesized SIPPs by employing a `green' thermal decomposition reaction using fatty amine ligands containing 12 to 18 carbons in length. Greater fatty amine chain length increased the polydispersity, particle concentration, iron concentration, and the stability of the SIPPs. Additionally, longer reflux times increased the diameter of the particles, but decreased the iron concentration, suggesting that shorter reaction times are preferable. Fourier transform infrared spectroscopy of the SIPPs indicates that the ligands are successfully bound to the FePt cores through the amine group. Superconducting quantum interference device magnetometry measurements suggest that all of the SIPPs were superparamagnetic at room temperature and that SIPPs synthesized using tetradecylamine had the highest saturation magnetization. Our findings indicate that the octadecylamine ligand, which is currently used for the routine synthesis of SIPPs, may not be optimal. Overall, we found that using tetradecylamine and a 30-min reflux reaction resulted in optimal particles with the highest degree of monodispersity, iron content, stability, and saturation magnetization.

  10. Magnetic iron oxide nanoparticles as drug delivery system in breast cancer

    NASA Astrophysics Data System (ADS)

    Marcu, A.; Pop, S.; Dumitrache, F.; Mocanu, M.; Niculite, C. M.; Gherghiceanu, M.; Lungu, C. P.; Fleaca, C.; Ianchis, R.; Barbut, A.; Grigoriu, C.; Morjan, I.

    2013-09-01

    Present work was focused on producing improved iron oxide nanoparticles for targeted drug delivery in breast cancer. Nanometric-sized iron oxide particles were synthesized by laser pyrolysis and were morphologically/structurally characterized. These new nanoparticles were compared with some commercial, chemically prepared iron oxide ones. Cytotoxicity and the anti-proliferation effects of nanoparticles were tested in vitro on the breast adenocarcinoma cell line MCF-7. Nanoparticles were further coated with the antracyclinic antibiotic Violamycine B1 and tested for the anti-tumor effect on MCF-7 cells. The nanoparticles produced by us seem more effective in vitro than the commercial ones, with respect to cellular uptake and VB1 delivery. Violamycine B1 bound on nanoparticles is as efficient as the free form, but is better delivered into tumor cells.

  11. Influence of Synthesis Parameters on Magnetization and Size of Iron Oxide Nanoparticles

    NASA Astrophysics Data System (ADS)

    Lak, Aidin; Ludwig, Frank; Grabs, Ilka-Maria; Garnweitner, Georg; Schilling, Meinhard

    2010-12-01

    The effect of the synthesis parameters precursor concentration, reaction temperature, reaction time, and heating rate on the non-hydrolytic synthesis of iron oxide nanoparticles was studied via statistical design of experiment (DOE) methodology. The net sample magnetic moments were determined by fluxgate magnetorelaxometry (MRX). Multiple linear regression analysis provided an empirical model where the net magnetic moments solely depend on precursor concentration and reaction temperature. The correctness of net magnetic moments determined from MRX measurements was verified by static M-H measurements on three selected samples. Also, good agreement of the particle core sizes determined by TEM and by fitting static M-H curves with the Langevin function was found for these samples. A similar dependence on synthesis parameters was observed for sample core sizes and the net sample magnetic moments based on comparative measurements on the selected samples, indicating that the core sizes solely depend on precursor concentration and reaction temperature but not on reaction time and heating rate. On the other hand, an increase of reaction time causes a broadening of the core size distribution.

  12. Introduction of biotin or folic acid into polypyrrole magnetite core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Nan, Alexandrina; Turcu, Rodica; Liebscher, Jürgen

    2013-11-01

    In order to contribute to the trend in contemporary research to develop magnetic core shell nanoparticles with better properties (reduced toxicity, high colloidal and chemical stability, wide scope of application) in straightforward and reproducible methods new core shell magnetic nanoparticles were developed based on polypyrrole shells functionalized with biotin and folic acid. Magnetite nanoparticles stabilized by sebacic acid were used as magnetic cores. The morphology of magnetite was determined by transmission electron microscopy TEM, while the chemical structure investigated by FT-IR.

  13. Introduction of biotin or folic acid into polypyrrole magnetite core-shell nanoparticles

    SciTech Connect

    Nan, Alexandrina; Turcu, Rodica; Liebscher, Jürgen

    2013-11-13

    In order to contribute to the trend in contemporary research to develop magnetic core shell nanoparticles with better properties (reduced toxicity, high colloidal and chemical stability, wide scope of application) in straightforward and reproducible methods new core shell magnetic nanoparticles were developed based on polypyrrole shells functionalized with biotin and folic acid. Magnetite nanoparticles stabilized by sebacic acid were used as magnetic cores. The morphology of magnetite was determined by transmission electron microscopy TEM, while the chemical structure investigated by FT-IR.

  14. Biomolecular crystals for material applications and a mechanistic study of an iron oxide nanoparticle synthesis

    NASA Astrophysics Data System (ADS)

    Falkner, Joshua Charles

    The three projects within this work address the difficulties of controlling biomolecular crystal formats (i.e. size and shape), producing 3-D ordered composite materials from biomolecular crystal templates, and understanding the mechanism of a practical iron oxide synthesis. The unifying thread consistent throughout these three topics is the development of methods to manipulate nanomaterials using a bottom-up approach. Biomolecular crystals are nanometer to millimeter sized crystals that have well ordered mesoporous solvent channels. The overall physical dimensions of these crystals are highly dependent on crystallization conditions. The controlled growth of micro- and nanoprotein crystals was studied to provide new pathways for creating smaller crystalline protein materials. This method produced tetragonal hen egg-white lysozyme crystals (250--100,000 nm) with near monodisperse size distributions (<15%). With this degree of control, existing protein crystal applications such as drug delivery and analytical sensors can reach their full potential. Applications for larger crystals with inherently ubiquitous pore structures could extend to materials used for membranes or templates. In this work, the porous structure of larger cowpea mosaic virus crystals was used to template metal nanoparticle growth within the body centered cubic crystalline network. The final composite material was found to have long range ordering of palladium and platinum nonocrystal aggregates (10nm) with symmetry consistent to the virus template. Nanoparticle synthesis itself is an immense field of study with an array of diverse applications. The final piece of this work investigates the mechanism behind a previously developed iron oxide synthesis to gain more understanding and direction to future synthesis strategies. The particle growth mechanism was found to proceed by the formation of a solvated iron(III)oleate complex followed by a reduction of iron (III) to iron (II). This unstable iron

  15. Characterization, Quantification, and Determination of the Toxicity of Iron Oxide Nanoparticles to the Bone Marrow Cells

    PubMed Central

    Paik, Sae-Yeol-Rim; Kim, Jong-Seok; Shin, Sung Jae; Ko, Sanghoon

    2015-01-01

    Iron oxide nanoparticles (IONPs) have been used to develop iron supplements for improving the bioavailability of iron in patients with iron deficiency, which is one of the most serious nutritional deficiencies in the world. Accurate information about the characteristics, concentration, and cytotoxicity of IONPs to the developmental and reproductive cells enables safe use of IONPs in the supplement industry. The objective of this study was to analyze the physicochemical properties and cytotoxicity of IONPs in bone marrow cells. We prepared three different types of iron samples (surface-modified iron oxide nanoparticles (SMNPs), IONPs, and iron citrate) and analyzed their physicochemical properties such as particle size distribution, zeta potential, and morphology. In addition, we examined the cytotoxicity of the IONPs in various kinds of bone marrow cells. We analyzed particle size distribution, zeta potential, iron levels, and subcellular localization of the iron samples in bone marrow cells. Our results showed that the iron samples were not cytotoxic to the bone marrow cells and did not affect the expression of cell surface markers and lipopolysaccharide (LPS)-induced the secretion of cytokines by murine bone marrow-derived dendritic cells (BMDCs). Our results may be used to investigate the interactions between nanoparticles and cells and tissues and the developmental toxicity of nanoparticles. PMID:26389886

  16. Characterization, Quantification, and Determination of the Toxicity of Iron Oxide Nanoparticles to the Bone Marrow Cells.

    PubMed

    Paik, Sae-Yeol-Rim; Kim, Jong-Seok; Shin, Sung Jae; Ko, Sanghoon

    2015-01-01

    Iron oxide nanoparticles (IONPs) have been used to develop iron supplements for improving the bioavailability of iron in patients with iron deficiency, which is one of the most serious nutritional deficiencies in the world. Accurate information about the characteristics, concentration, and cytotoxicity of IONPs to the developmental and reproductive cells enables safe use of IONPs in the supplement industry. The objective of this study was to analyze the physicochemical properties and cytotoxicity of IONPs in bone marrow cells. We prepared three different types of iron samples (surface-modified iron oxide nanoparticles (SMNPs), IONPs, and iron citrate) and analyzed their physicochemical properties such as particle size distribution, zeta potential, and morphology. In addition, we examined the cytotoxicity of the IONPs in various kinds of bone marrow cells. We analyzed particle size distribution, zeta potential, iron levels, and subcellular localization of the iron samples in bone marrow cells. Our results showed that the iron samples were not cytotoxic to the bone marrow cells and did not affect the expression of cell surface markers and lipopolysaccharide (LPS)-induced the secretion of cytokines by murine bone marrow-derived dendritic cells (BMDCs). Our results may be used to investigate the interactions between nanoparticles and cells and tissues and the developmental toxicity of nanoparticles.

  17. Ferromagnetic Resonance of Superparamagnetic Iron Oxide Nanoparticles for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Wosik, Jaroslaw; Xue, Lian; Xie, Lei-Ming; Chan, Dan

    2003-03-01

    Ferromagnetic Resonance (FMR) techniques were used to investigate superparamagnetic iron oxide (SPIO) nanoparticles (NP) with different coatings and sizes ranging from 5 to 50 nm in diameter. The samples were synthesized by standard procedures with or without coating and fractionated by differential centrifugations to generate particles of different sizes. In order to improve detection sensitivity of pathological tissue changes such as atherosclerosis, smaller particles of less than 10 nm were selected for contrast-enhanced magnetic resonance imaging (MRI). We have investigated uncoated, lipid encapsulated and dextran coated SPIO samples in liquid suspension, dry, and in mixed-with-wax forms. The angular dependence of the FMR of NP with easy axes aligned and frozen in wax was measured. Shapes and shifts of FMR lines for each sample was analyzed for size and anisotropy. Examples of rabbit's aorta MRI T2-weigted images showing proton relaxation time T2 shortening due to the pretreatment with SPIO will be presented and discussed.

  18. Preparation of polylysine-modified superparamagnetic iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Yang, Gao; Zhang, Baolin; Wang, Jun; Xie, Songbo; Li, Xuan

    2015-01-01

    Polylysine (PLL) coated iron oxide nanoparticles (SPIONs) have potential in biomedical application. In the present work PEG coated SPIONs (PEG-SPIONs) with the particle size of 9.4±1.4 nm were synthesized by thermal decomposition of Fe(acac)3 in PEG, and then coated with PLL (PLL/PEG-SPIONs). The PEG-SPIONs and PLL/PEG-SPIONs were superparamagnetic with the saturation magnetization of 53 and 44 emu/g, respectively. The hydrodynamic diameter of PEG-SPIONs in deionized water was 18.8 nm, which increased to 21.3-28.2 nm after mixing with different amount of PLL. The zeta potentials of PLL/PEG-SPIONs were -8.9 - -3.4 mV which were changing with time. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses indicated that PLL was attached to the PEG-SPIONs.

  19. Heterobifunctional PEG Ligands for Bioconjugation Reactions on Iron Oxide Nanoparticles

    PubMed Central

    Bloemen, Maarten; Van Stappen, Thomas; Willot, Pieter; Lammertyn, Jeroen; Koeckelberghs, Guy; Geukens, Nick; Gils, Ann; Verbiest, Thierry

    2014-01-01

    Ever since iron oxide nanoparticles have been recognized as promising scaffolds for biomedical applications, their surface functionalization has become even more important. We report the synthesis of a novel polyethylene glycol-based ligand that combines multiple advantageous properties for these applications. The ligand is covalently bound to the surface via a siloxane group, while its polyethylene glycol backbone significantly improves the colloidal stability of the particle in complex environments. End-capping the molecule with a carboxylic acid introduces a variety of coupling chemistry possibilities. In this study an antibody targeting plasminogen activator inhibitor-1 was coupled to the surface and its presence and binding activity was assessed by enzyme-linked immunosorbent assay and surface plasmon resonance experiments. The results indicate that the ligand has high potential towards biomedical applications where colloidal stability and advanced functionality is crucial. PMID:25275378

  20. Characterization of the magnetic moment distribution in low-concentration solutions of iron oxide nanoparticles by a high-T{sub c} superconducting quantum interference device magnetometer

    SciTech Connect

    Saari, M. M. Sakai, K.; Kiwa, T.; Tsukada, K.; Sasayama, T.; Yoshida, T.

    2015-05-07

    We developed a highly sensitive AC/DC magnetometer using a high-temperature superconductor superconducting quantum interference device for the evaluation of magnetic nanoparticles in solutions. Using the developed system, we investigated the distribution of magnetic moments of iron oxide multi-core particles of 100 nm at various iron concentrations that are lower than 96 μg/ml by analyzing the measured magnetization curves. Singular value decomposition and non-regularized non-negative least-squares methods were used during the reconstruction of the distribution. Similar distributions were obtained for all concentrations, and the iron concentration could be determined from the measured magnetization curves. The measured harmonics upon the excitation of AC and DC magnetic fields curves agreed well with the harmonics simulated based on the reconstructed magnetization curves, implying that the magnetization curves of magnetic nanoparticles were successfully obtained as we will show in the article. We compared the magnetization curves between multi-core particles of 100 nm and 130 nm, composed of 12-nm iron oxide nanoparticles. A distinctive magnetic property between the 100 nm and 130 nm particles in low-concentration solutions was successfully characterized. The distribution characteristic of magnetic moments suggests that the net magnetic moment in a multi-core particle is affected by the size of the magnetic cores and their degree of aggregation. Exploration of magnetic properties with high sensitivity can be expected using the developed system.

  1. Magnetic and fluorescent core-shell nanoparticles for ratiometric pH sensing

    NASA Astrophysics Data System (ADS)

    Lapresta-Fernández, Alejandro; Doussineau, Tristan; Dutz, Silvio; Steiniger, Frank; Moro, Artur J.; Mohr, Gerhard J.

    2011-10-01

    This paper describes the preparation of nanoparticles composed of a magnetic core surrounded by two successive silica shells embedding two fluorophores, showing uniform nanoparticle size (50-60 nm in diameter) and shape, which allow ratiometric pH measurements in the pH range 5-8. Uncoated iron oxide magnetic nanoparticles (~10 nm in diameter) were formed by the coprecipitation reaction of ferrous and ferric salts. Then, they were added to a water-in-oil microemulsion where the hydrophilic silica shells were obtained through hydrolysis and condensation of tetraethoxyorthosilicate together with the corresponding silylated dye derivatives—a sulforhodamine was embedded in the inner silica shell and used as the reference dye while a pH-sensitive fluorescein was incorporated in the outer shell as the pH indicator. The magnetic nanoparticles were characterized using vibrating sample magnetometry, dynamic light scattering, transmission electron microscopy, x-ray diffraction and Fourier transform infrared spectroscopy. The relationship between the analytical parameter, that is, the ratio of fluorescence between the sensing and reference dyes versus the pH was adjusted to a sigmoidal fit using a Boltzmann type equation giving an apparent pKa value of 6.8. The fluorescence intensity of the reference dye did not change significantly (~3.0%) on modifying the pH of the nanoparticle dispersion. Finally, the proposed method was statistically validated against a reference procedure using samples of water and physiological buffer with 2% of horse serum, indicating that there are no significant statistical differences at a 95% confidence level.

  2. Pharmaceutical formulation of HSA hybrid coated iron oxide nanoparticles for magnetic drug targeting.

    PubMed

    Zaloga, Jan; Pöttler, Marina; Leitinger, Gerd; Friedrich, Ralf P; Almer, Gunter; Lyer, Stefan; Baum, Eva; Tietze, Rainer; Heimke-Brinck, Ralph; Mangge, Harald; Dörje, Frank; Lee, Geoffrey; Alexiou, Christoph

    2016-04-01

    In this work we present a new formulation of superparamagnetic iron oxide nanoparticles (SPIONs) for magnetic drug targeting. The particles were reproducibly synthesized from current good manufacturing practice (cGMP) - grade substances. They were surface coated using fatty acids as anchoring molecules for human serum albumin. We comprehensively characterized the physicochemical core-shell structure of the particles using sophisticated methods. We investigated biocompatibility and cellular uptake of the particles using an established flow cytometric method in combination with microwave-plasma assisted atomic emission spectroscopy (MP-AES). The cytotoxic drug mitoxantrone was adsorbed on the protein shell and we showed that even in complex media it is slowly released with a close to zero order kinetics. We also describe an in vitro proof-of-concept assay in which we clearly showed that local enrichment of this SPION-drug conjugate with a magnet allows site-specific therapeutic effects. PMID:26854862

  3. Mutagenic Effects of Iron Oxide Nanoparticles on Biological Cells

    PubMed Central

    Dissanayake, Niluka M.; Current, Kelley M.; Obare, Sherine O.

    2015-01-01

    In recent years, there has been an increased interest in the design and use of iron oxide materials with nanoscale dimensions for magnetic, catalytic, biomedical, and electronic applications. The increased manufacture and use of iron oxide nanoparticles (IONPs) in consumer products as well as industrial processes is expected to lead to the unintentional release of IONPs into the environment. The impact of IONPs on the environment and on biological species is not well understood but remains a concern due to the increased chemical reactivity of nanoparticles relative to their bulk counterparts. This review article describes the impact of IONPs on cellular genetic components. The mutagenic impact of IONPs may damage an organism’s ability to develop or reproduce. To date, there has been experimental evidence of IONPs having mutagenic interactions on human cell lines including lymphoblastoids, fibroblasts, microvascular endothelial cells, bone marrow cells, lung epithelial cells, alveolar type II like epithelial cells, bronchial fibroblasts, skin epithelial cells, hepatocytes, cerebral endothelial cells, fibrosarcoma cells, breast carcinoma cells, lung carcinoma cells, and cervix carcinoma cells. Other cell lines including the Chinese hamster ovary cells, mouse fibroblast cells, murine fibroblast cells, Mytilus galloprovincialis sperm cells, mice lung cells, murine alveolar macrophages, mice hepatic and renal tissue cells, and vero cells have also shown mutagenic effects upon exposure to IONPs. We further show the influence of IONPs on microorganisms in the presence and absence of dissolved organic carbon. The results shed light on the transformations IONPs undergo in the environment and the nature of the potential mutagenic impact on biological cells. PMID:26437397

  4. Tuning upconversion through energy migration in core-shell nanoparticles.

    PubMed

    Wang, Feng; Deng, Renren; Wang, Juan; Wang, Qingxiao; Han, Yu; Zhu, Haomiao; Chen, Xueyuan; Liu, Xiaogang

    2011-10-23

    Photon upconversion is promising for applications such as biological imaging, data storage or solar cells. Here, we have investigated upconversion processes in a broad range of gadolinium-based nanoparticles of varying composition. We show that by rational design of a core-shell structure with a set of lanthanide ions incorporated into separated layers at precisely defined concentrations, efficient upconversion emission can be realized through gadolinium sublattice-mediated energy migration for a wide range of lanthanide activators without long-lived intermediary energy states. Furthermore, the use of the core-shell structure allows the elimination of deleterious cross-relaxation. This effect enables fine-tuning of upconversion emission through trapping of the migrating energy by the activators. Indeed, the findings described here suggest a general approach to constructing a new class of luminescent materials with tunable upconversion emissions by controlled manipulation of energy transfer within a nanoscopic region.

  5. pH sensitive core-shell magnetic nanoparticles for targeted drug delivery in cancer therapy.

    PubMed

    Lungu, Iulia Ioana; Rădulescu, Marius; Mogoşanu, George Dan; Grumezescu, Alexandru Mihai

    2016-01-01

    In the last decade, nanobiotechnology has evolved rapidly with an extensive impact on biomedical area. In order to improve bioavailability and minimize adverse effects, drug delivery systems based on magnetic nanocomposites are under development mainly for cancer imaging and antitumor therapy. In this regard, pH sensitive core-shell magnetic nanoparticles (NPs) with accurate controlled size and shape are synthesized by various modern methods, such as homogeneous precipitation, coprecipitation, microemulsion or polyol approaches, high temperature and hydrothermal reactions, sol-gel reactions, aerosol÷vapor processes and sonolysis. Due to their unique combined physico-chemical and biological properties (such as higher dispensability, chemical and thermal stability, biocompatibility), pH responsive core-shell magnetic NPs are widely investigated for controlled release of cytostatic drugs into the tumor site by means of pH change: magnetite@silicon dioxide (Fe3O4@SiO2), Fe3O4@titanium dioxide (TiO2), β-thiopropionate-polyethylene glycol (PEG)-modified Fe3O4@mSiO2, Fe3O4 NPs core coated with SiO2 with an imidazole group modified PEG-polypeptide (mPEG-poly-L-Asparagine), polyacrylic acid (PAA) and folic acid (FA) coating of the iron oxide NP core, methoxy polyethylene glycol-block-polymethacrylic acid-block-polyglycerol monomethacrylate (MPEG-b-PMAA-b-PGMA) attached by a PGMA block to a Fe3O4 core, PEG-modified polyamidoamine (PAMAM) dendrimer shell with Fe3O4 core and mesoporous silica coated on Fe3O4, mostly coated with an anticancer drug. This review paper highlights the modern research directions currently employed to demonstrate the utility of the pH responsive core-shell magnetic NPs in diagnosis and treatment of oncological diseases. PMID:27151685

  6. The role of interfacial metal silicates on the magnetism in FeCo/SiO{sub 2} and Fe{sub 49%}Co{sub 49%}V{sub 2%}/SiO{sub 2} core/shell nanoparticles

    SciTech Connect

    Desautels, R. D.; Freeland, J. W.; Rowe, M. P.; Lierop, J. van

    2015-05-07

    We have investigated the role of spontaneously formed interfacial metal silicates on the magnetism of FeCo/SiO{sub 2} and Fe{sub 49%}Co{sub 49%}V{sub 2%}/SiO{sub 2} core/shell nanoparticles. Element specific x-ray absorption and photoelectron spectroscopy experiments have identified the characteristic spectral features of metallic iron and cobalt from within the nanoparticle core. In addition, metal silicates of iron, cobalt, and vanadium were found to have formed spontaneously at the interface between the nanoparticle core and silica shell. X-ray magnetic circular dichroism experiments indicated that the elemental magnetism was a result of metallic iron and cobalt with small components from the iron, cobalt, and vanadium silicates. Magnetometry experiments have shown that there was no exchange bias loop shift in the FeCo nanoparticles; however, exchange bias from antiferromagnetic vanadium oxide was measured in the V-doped nanoparticles. These results showed clearly that the interfacial metal silicates played a significant role in the magnetism of these core/shell nanoparticles, and that the vanadium percolated from the FeCo-cores into the SiO{sub 2}-based interfacial shell.

  7. Core-shell nanoparticle controlled hATSCs neurogenesis for neuropathic pain therapy.

    PubMed

    Choi, Jee In; Cho, Hyun Tae; Jee, Min Ki; Kang, Soo Kyung

    2013-07-01

    A stem cell-based strategy for tissue engineering in regenerative medicine is crucial to produce and effective therapeutic replacement of injured or damaged tissues. This type of therapeutic replacement requires interaction with the cells and tissues via the incorporation of a beneficial physical microenvironment and cellular biochemical signals. Recently, we studied a cell-function modifying factor, core-shell nanoparticles consisting of an SPIO (superparamagnetic iron oxide) core covered with a photonic ZnO shell for human adipose tissue-derived stem cells (hATSCs) that regulate various cellular functions: self-renewal, neurogenesis, and dedifferentiation. We proposed an alternative method of stem cell culture that focuses on the use of Zn++ Finger nanoparticles for stem cell expansion and transdifferentiation modulation in vitro and in in vivo spinal cord injury models. Our study showed that treating hATSC cultures with nanoscale particles could lead to active cell proliferation and self-renewal and could promote nuclear Dicer-regulation of several functional molecules, Oct4 and Glutathione peroxidase 3 (GPx3), and the abundance of specific functional proteins that have been observed using biochemical analysis. These biochemical changes in hATSCs induced the functional development of multiple differentiation potencies such as β-cells and neural cells; specifically, the ability to differentiation into GABA-secreting cells was significantly improved in in vitro- and in vivo-induced animal lesions with significantly improved therapeutic modality.

  8. Melt-grafting for the synthesis of core-shell nanoparticles with ultra-high dispersant density.

    PubMed

    Zirbs, Ronald; Lassenberger, Andrea; Vonderhaid, Iris; Kurzhals, Steffen; Reimhult, Erik

    2015-07-01

    Superparamagnetic iron oxide nanoparticles (NPs) are used in a rapidly expanding number of applications in e.g. the biomedical field, for which brushes of biocompatible polymers such as poly(ethylene glycol) (PEG) have to be densely grafted to the core. Grafting of such shells to monodisperse iron oxide NPs has remained a challenge mainly due to the conflicting requirements to replace the ligand shell of as-synthesized NPs with irreversibly bound PEG dispersants. We introduce a general two-step method to graft PEG dispersants from a melt to iron oxide NPs first functionalized with nitrodopamine (NDA). This method yields uniquely dense spherical PEG-brushes (∼3 chains per nm(2) of PEG(5 kDa)) compared to existing methods, and remarkably colloidally stable NPs also under challenging conditions. PMID:26061616

  9. Magnetic iron oxide nanoparticles: Synthesis and surface coating techniques for biomedical applications

    NASA Astrophysics Data System (ADS)

    Sun, Sheng-Nan; Wei, Chao; Zhu, Zan-Zan; Hou, Yang-Long; Subbu, S. Venkatraman; Xu, Zhi-Chuan

    2014-03-01

    Iron oxide nanoparticles are the most popular magnetic nanoparticles used in biomedical applications due to their low cost, low toxicity, and unique magnetic property. Magnetic iron oxide nanoparticles, including magnetite (Fe3O4) and maghemite (γ-Fe2O3), usually exhibit a superparamagnetic property as their size goes smaller than 20 nm, which are often denoted as superparamagnetic iron oxide nanoparticles (SPIONs) and utilized for drug delivery, diagnosis, therapy, and etc. This review article gives a brief introduction on magnetic iron oxide nanoparticles in terms of their fundamentals of magnetism, magnetic resonance imaging (MRI), and drug delivery, as well as the synthesis approaches, surface coating, and application examples from recent key literatures. Because the quality and surface chemistry play important roles in biomedical applications, our review focuses on the synthesis approaches and surface modifications of iron oxide nanoparticles. We aim to provide a detailed introduction to readers who are new to this field, helping them to choose suitable synthesis methods and to optimize the surface chemistry of iron oxide nanoparticles for their interests.

  10. Formulation design for target delivery of iron nanoparticles to TCE zones.

    PubMed

    Wang, Ziheng; Acosta, Edgar

    2013-12-01

    Nanoparticles of zero-valent iron (NZVI) are effective reducing agents for some dense non-aqueous phase liquid (DNAPL) contaminants such as trichloroethylene (TCE). However, target delivery of iron nanoparticles to DNAPL zones in the aquifer remains an elusive feature for NZVI technologies. This work discusses three strategies to deliver iron nanoparticles to DNAPL zones. To this end, iron oxide nanoparticles coated with oleate (OL) ions were used as stable analogs for NZVI. The OL-coated iron oxide nanoparticles are rendered lipophilic via (a) the addition of CaCl2, (b) acidification, or (c) the addition of a cationic surfactant, benzethonium chloride (BC). Mixtures of OL and BC show promise as a target delivery strategy due to the high stability of the nanoparticles in water, and their preferential partition into TCE in batch experiments. Column tests show that while the OL-BC coated iron oxide nanoparticles remain largely mobile in TCE-free columns, a large fraction of these particles are retained in TCE-contaminated columns, confirming the effectiveness of this target delivery strategy.

  11. Mechanism of the reduction of hexavalent chromium by organo-montmorillonite supported iron nanoparticles.

    PubMed

    Wu, Pingxiao; Li, Shuzhen; Ju, Liting; Zhu, Nengwu; Wu, Jinhua; Li, Ping; Dang, Zhi

    2012-06-15

    Iron nanoparticles exhibit greater reactivity than micro-sized Fe(0), and they impart advantages for groundwater remediation. In this paper, supported iron nanoparticles were synthesized to further enhance the speed and efficiency of remediation. Natural montmorillonite and organo-montmorillonite were chosen as supporting materials. The capacity of supported iron nanoparticles was evaluated, compared to unsupported iron nanoparticles, for the reduction of aqueous Cr(VI). The reduction of Cr(VI) was much greater with organo-montmorillonite supported iron nanoparticles and fitted the pseudo-second order equation better. With a dose at 0.47 g/L, a total removal capacity of 106 mg Cr/g Fe(0) was obtained. Other factors that affect the efficiency of Cr(VI) removal, such as pH values, the initial Cr(VI) concentration and storage time of nanoparticles were investigated. X-ray photoelectron spectrometry (XPS) and X-ray absorption near edge structure (XANES) were used to figure out the mechanism of the removal of Cr(VI). XPS indicated that the Cr(VI) bound to the particle surface was completely reduced to Cr(III) under a range of conditions. XANES confirmed that the Cr(VI) reacted with iron nanoparticles was completely reduced to Cr(III).

  12. Excellent improvement in the static and dynamic magnetic properties of carbon coated iron nanoparticles for microwave absorption

    NASA Astrophysics Data System (ADS)

    Khani, Omid; Shoushtari, Morteza Zargar; Farbod, Mansoor

    2015-11-01

    Carbon coated iron nanoparticles were synthesized, using a simple arc-discharge method. The morphology and the internal structure of the core/shell nanoparticles were studied, using field emission scanning electron microscopy and transmission electron microscopy. X-ray diffraction analysis showed that both magnetic α-Fe and nonmagnetic γ-Fe phases existed in the as-prepared particles. In order to improve the static and dynamic magnetic properties of the core/shell nanoparticles, the produced nanocapsules were annealed in argon atmosphere at two different temperatures. Hysteresis loops revealed that the value of the saturation magnetization (MS) increased more than 4.1 times of its original value by annealing and this led to 70% increase in the imaginary part of the permeability. Phase analysis showed that heat treatment eliminated the nonmagnetic γ-Fe phase completely. The reflection loss plots were studied for composite layers containing 20 vol% of the annealed and not annealed nanocapsules. One of the absorber layers which contained annealed nanocapsules showed at least -10 dB loss in the whole G, C, X and Ku frequency bands and the optimal absorption exceeded -37 dB at 5.8 GHz for the as-prepared sample with a thickness of 3.2 mm. The results revealed that the magnetic properties of the arc-made Fe/C core/shell nanoparticle can be improved significantly by annealing in argon.

  13. Water-soluble core/shell nanoparticles for proton therapy through particle-induced radiation

    NASA Astrophysics Data System (ADS)

    Park, Jeong Chan; Jung, Myung-Hwan; Kim, Maeng Jun; Kim, Kye-Ryung

    2015-02-01

    Metallic nanoparticles have been used in biomedical applications such as magnetic resonance imaging (MRI), therapy, and drug delivery systems. Metallic nanoparticles as therapeutic tools have been demonstrated using radio-frequency magnetic fields or near-infrared light. Recently, therapeutic applications of metallic nanomaterials combined with proton beams have been reported. Particle-induced radiation from metallic nanoparticles, which can enhance the therapeutic effects of proton therapy, was released when the nanoparticles were bombarded by a high-energy proton beam. Core/shell nanoparticles, especially Au-coated magnetic nanoparticles, have drawn attention in biological applications due to their attractive characteristics. However, studies on the phase transfer of organic-ligand-based core/shell nanoparticles into water are limited. Herein, we demonstrated that hydrophobic core/shell structured nanomaterials could be successfully dispersed in water through chloroform/surfactant mixtures. The effects of the core/shell nanomaterials and the proton irradiation on Escherichia coli (E. coli) were also explored.

  14. Superparamagnetic Iron Oxide Nanoparticle-Based Delivery Systems for Biotherapeutics

    PubMed Central

    Mok, Hyejung; Zhang, Miqin

    2014-01-01

    Introduction Superparamagnetic iron oxide nanoparticle (SPION)-based carrier systems have many advantages over other nanoparticle-based systems. They are biocompatible, biodegradable, facilely tunable, and superparamagnetic and thus controllable by an external magnetic field. These attributes enable their broad biomedical applications. In particular, magnetically-driven carriers are drawing considerable interest as an emerging therapeutic delivery system because of their superior delivery efficiency. Area covered This article reviews the recent advances in use of SPION-based carrier systems to improve the delivery efficiency and target specificity of biotherapeutics. We examine various formulations of SPION-based delivery systems, including SPION micelles, clusters, hydrogels, liposomes, and micro/nanospheres, as well as their specific applications in delivery of biotherapeutics. Expert opinion Recently, biotherapeutics including therapeutic cells, proteins and genes have been studied as alternative treatments to various diseases. Despite the advantages of high target specificity and low adverse effects, clinical translation of biotherapeutics has been hindered by the poor stability and low delivery efficiency compared to chemical drugs. Accordingly, biotherapeutic delivery systems that can overcome these limitations are actively pursued. SPION-based materials can be ideal candidates for developing such delivery systems because of their excellent biocompatibility and superparamagnetism that enables long-term accumulation/retention at target sites by utilization of a suitable magnet. In addition, synthesis technologies for production of finely-tuned, homogeneous SPIONs have been well developed, which may promise their rapid clinical translation. PMID:23199200

  15. Solvothermal synthesis and characterization of monodisperse superparamagnetic iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, Shichuan; Zhang, Tonglai; Tang, Runze; Qiu, Hao; Wang, Caiqin; Zhou, Zunning

    2015-04-01

    A series of magnetic iron oxide nanoparticle clusters with different structure guide agents were synthesized by a modified solvothermal method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analyses (TG), a vibrating sample magnetometer (VSM) and Fourier transform infrared spectroscopy (FTIR). It is found that the superparamagnetic nanoparticles guided by NaCit (sodium citrate) have high saturation magnetization (Ms) of 69.641 emu/g and low retentivity (Mr) of 0.8 emu/g. Guiding to form superparamagnetic clusters with size range of 80-110 nm, the adherent small-molecule citrate groups on the surface prevent the prefabricated ferrite crystals growing further. In contrast, the primary small crystal guided and stabilized by the PVP long-chain molecules assemble freely to larger ones and stop growing in size range of 100-150 nm, which has saturation magnetization (Ms) of 97.979 emu/g and retentivity (Mr) of 46.323 emu/g. The relevant formation mechanisms of the two types of samples are proposed at the end. The superparamagnetic ferrite clusters guided by sodium citrate are expected to be used for movement controlling of passive interference particles to avoid aggregation and the sample guided by PVP will be a candidate of nanometer wave absorbing material.

  16. Dendritic carbon architectures formed by nanotube core-directed diffusion-limited aggregation of nanoparticles.

    PubMed

    Liu, Zhenyu; Kong, Xiaohui

    2010-08-28

    A regular array of fractal patterns with macroscopic dendritic carbon architecture was prepared by catalytic chemical vapor deposition (CVD). The dendritic carbon architectures have micrometre-sized stems and hyperbranches evolved by lateral growth, and they are formed by diffusion-limited aggregation of carbon-encapsulated iron nanoparticle building blocks generated from catalytic pyrolysis of toluene, which is directed by carbon nanotube cores, and followed by subsequent restructuring from surface to bulk. Incorporation of such proposed processes in Monte Carlo simulations generates dendritic architectures similar to the morphologies observed from the experiments. The findings provide direct information to the time resolved evolution of the morphology and microstructure of the dendritic carbon architecture, which mimic the nature behavior as snowflake attaching on the tree branches. Those will be important to understand the growth of vapor grown carbon fibers and carbon filamentous structures, and further possibility to control branching out of vapor grown carbon fibers. PMID:20607160

  17. Zero Valent Iron: Impact of Anions Present during Synthesis on Subsequent Nanoparticle Reactivity

    SciTech Connect

    Moore, Kirsten; Forsberg, Brady; Baer, Donald R.; Arnold, William A.; Penn, R. Lee

    2011-10-01

    Zero-valent iron particles are an effective remediation technology for groundwater contaminated with halogenated organic compounds. In particular, nano-scale zero-valent iron is a promising material for remediation due to its high specific surface area, which results in faster rate constants and more effective use of the iron. An aspect of iron nanoparticle reactivity that has not been explored is the impact of anions present during iron metal nanoparticle synthesis. Solutions containing chloride, phosphate, sulfate, and nitrate anions and ferric ions were used to generate iron oxide nanoparticles. The resulting materials were dialyzed to remove dissolved byproducts and then dried and reduced by hydrogen gas at high temperature. The reactivity of the resulting zero valent iron nanoparticles was quantified by monitoring the kinetics as well as products of carbon tetrachloride reduction, and significant differences in reactivity and chloroform yield were observed. The reactivity of nanoparticles prepared in the presence of sulfate and phosphate demonstrated the highest reactivity and chloroform yield. Furthermore, substantial variations in the solid-state products of oxidation (magnetite, iron sulfide, and goethite, among others) were also observed.

  18. Melt-grafting for the synthesis of core-shell nanoparticles with ultra-high dispersant density

    NASA Astrophysics Data System (ADS)

    Zirbs, Ronald; Lassenberger, Andrea; Vonderhaid, Iris; Kurzhals, Steffen; Reimhult, Erik

    2015-06-01

    Superparamagnetic iron oxide nanoparticles (NPs) are used in a rapidly expanding number of applications in e.g. the biomedical field, for which brushes of biocompatible polymers such as poly(ethylene glycol) (PEG) have to be densely grafted to the core. Grafting of such shells to monodisperse iron oxide NPs has remained a challenge mainly due to the conflicting requirements to replace the ligand shell of as-synthesized NPs with irreversibly bound PEG dispersants. We introduce a general two-step method to graft PEG dispersants from a melt to iron oxide NPs first functionalized with nitrodopamine (NDA). This method yields uniquely dense spherical PEG-brushes (~3 chains per nm2 of PEG(5 kDa)) compared to existing methods, and remarkably colloidally stable NPs also under challenging conditions.Superparamagnetic iron oxide nanoparticles (NPs) are used in a rapidly expanding number of applications in e.g. the biomedical field, for which brushes of biocompatible polymers such as poly(ethylene glycol) (PEG) have to be densely grafted to the core. Grafting of such shells to monodisperse iron oxide NPs has remained a challenge mainly due to the conflicting requirements to replace the ligand shell of as-synthesized NPs with irreversibly bound PEG dispersants. We introduce a general two-step method to graft PEG dispersants from a melt to iron oxide NPs first functionalized with nitrodopamine (NDA). This method yields uniquely dense spherical PEG-brushes (~3 chains per nm2 of PEG(5 kDa)) compared to existing methods, and remarkably colloidally stable NPs also under challenging conditions. Electronic supplementary information (ESI) available: The ESI contains details on additional synthetic protocols and characterization. See DOI: 10.1039/c5nr02313k

  19. Physicochemical Characterization of Nebulized Superparamagnetic Iron Oxide Nanoparticles (SPIONs)

    PubMed Central

    Graczyk, Halshka; Bryan, Louise C.; Lewinski, Nastassja; Suarez, Guillaume; Coullerez, Geraldine; Bowen, Paul

    2015-01-01

    Abstract Background: Aerosol-mediated delivery of nano-based therapeutics to the lung has emerged as a promising alternative for treatment and prevention of lung diseases. Superparamagnetic iron oxide nanoparticles (SPIONs) have attracted significant attention for such applications due to their biocompatibility and magnetic properties. However, information is lacking about the characteristics of nebulized SPIONs for use as a therapeutic aerosol. To address this need, we conducted a physicochemical characterization of nebulized Rienso, a SPION-based formulation for intravenous treatment of anemia. Methods: Four different concentrations of SPION suspensions were nebulized with a one-jet nebulizer. Particle size was measured in suspension by transmission electron microscopy (TEM), photon correlation spectroscopy (PCS), and nanoparticle tracking analysis (NTA), and in the aerosol by a scanning mobility particle sizer (SMPS). Results: The average particle size in suspension as measured by TEM, PCS, and NTA was 9±2 nm, 27±7 nm, and 56±10 nm, respectively. The particle size in suspension remained the same before and after the nebulization process. However, after aerosol collection in an impinger, the suspended particle size increased to 159±46 nm as measured by NTA. The aerosol particle concentration increased linearly with increasing suspension concentration, and the aerodynamic diameter remained relatively stable at around 75 nm as measured by SMPS. Conclusions: We demonstrated that the total number and particle size in the aerosol were modulated as a function of the initial concentration in the nebulizer. The data obtained mark the first known independent characterization of nebulized Rienso and, as such, provide critical information on the behavior of Rienso nanoparticles in an aerosol. The data obtained in this study add new knowledge to the existing body of literature on potential applications of SPION suspensions as inhaled aerosol therapeutics. PMID

  20. Cloaking core-shell nanoparticles from conducting electrons in solids.

    PubMed

    Liao, Bolin; Zebarjadi, Mona; Esfarjani, Keivan; Chen, Gang

    2012-09-21

    In this Letter, we aim at making nanoparticles embedded in a host semiconductor with a size comparable to electronic wavelengths "invisible" to the electron transport. Inspired by the recent progress made in optics and working within the framework of the expansion of partial waves, we demonstrate that the opposite effects imposed by potential barriers and wells of a core-shell nanoparticle on the phase shifts associated with the scattered electron wave could make the scattering cross section of the first two partial waves vanish simultaneously. We show that this is sufficient to cloak the nanoparticle from being detected by electrons with specific energy in the sense that a total scattering cross section smaller than 0.01% of the physical cross section can be obtained and a 4 orders of magnitude difference in the total scattering cross section can be presented within an energy range of only 40 meV, indicating possible applications of the "electron cloaks" as novel electronic switches and sensors, and in efficient energy harvesting and conversion technologies. PMID:23005976

  1. Cloaking core-shell nanoparticles from conducting electrons in solids.

    PubMed

    Liao, Bolin; Zebarjadi, Mona; Esfarjani, Keivan; Chen, Gang

    2012-09-21

    In this Letter, we aim at making nanoparticles embedded in a host semiconductor with a size comparable to electronic wavelengths "invisible" to the electron transport. Inspired by the recent progress made in optics and working within the framework of the expansion of partial waves, we demonstrate that the opposite effects imposed by potential barriers and wells of a core-shell nanoparticle on the phase shifts associated with the scattered electron wave could make the scattering cross section of the first two partial waves vanish simultaneously. We show that this is sufficient to cloak the nanoparticle from being detected by electrons with specific energy in the sense that a total scattering cross section smaller than 0.01% of the physical cross section can be obtained and a 4 orders of magnitude difference in the total scattering cross section can be presented within an energy range of only 40 meV, indicating possible applications of the "electron cloaks" as novel electronic switches and sensors, and in efficient energy harvesting and conversion technologies.

  2. Gold core@silver semishell Janus nanoparticles prepared by interfacial etching

    NASA Astrophysics Data System (ADS)

    Chen, Limei; Deming, Christopher P.; Peng, Yi; Hu, Peiguang; Stofan, Jake; Chen, Shaowei

    2016-07-01

    Gold core@silver semishell Janus nanoparticles were prepared by chemical etching of Au@Ag core-shell nanoparticles at the air/water interface. Au@Ag core-shell nanoparticles were synthesized by chemical deposition of a silver shell onto gold seed colloids followed by the self-assembly of 1-dodecanethiol onto the nanoparticle surface. The nanoparticles then formed a monolayer on the water surface of a Langmuir-Blodgett trough, and part of the silver shell was selectively etched away by the mixture of hydrogen peroxide and ammonia in the water subphase, where the etching was limited to the side of the nanoparticles that was in direct contact with water. The resulting Janus nanoparticles exhibited an asymmetrical distribution of silver on the surface of the gold cores, as manifested in transmission electron microscopy, UV-vis absorption, and X-ray photoelectron spectroscopy measurements. Interestingly, the Au@Ag semishell Janus nanoparticles exhibited enhanced electrocatalytic activity in oxygen reduction reactions, as compared to their Au@Ag and Ag@Au core-shell counterparts, likely due to a synergistic effect between the gold cores and silver semishells that optimized oxygen binding to the nanoparticle surface.Gold core@silver semishell Janus nanoparticles were prepared by chemical etching of Au@Ag core-shell nanoparticles at the air/water interface. Au@Ag core-shell nanoparticles were synthesized by chemical deposition of a silver shell onto gold seed colloids followed by the self-assembly of 1-dodecanethiol onto the nanoparticle surface. The nanoparticles then formed a monolayer on the water surface of a Langmuir-Blodgett trough, and part of the silver shell was selectively etched away by the mixture of hydrogen peroxide and ammonia in the water subphase, where the etching was limited to the side of the nanoparticles that was in direct contact with water. The resulting Janus nanoparticles exhibited an asymmetrical distribution of silver on the surface of the gold

  3. The ultimate step towards a tailored engineering of core@shell and core@shell@shell nanoparticles.

    PubMed

    Llamosa, D; Ruano, M; Martínez, L; Mayoral, A; Roman, E; García-Hernández, M; Huttel, Y

    2014-11-21

    Complex core@shell and core@shell@shell nanoparticles are systems that combine the functionalities of the inner core and outer shell materials together with new physico-chemical properties originated by their low (nano) dimensionality. Such nanoparticles are of prime importance in the fast growing field of nanotechnology as building blocks for more sophisticated systems and a plethora of applications. Here, it is shown that although conceptually simple a modified gas aggregation approach allows the one-step generation of well-controlled complex nanoparticles. In particular, it is demonstrated that the atoms of the core and the shell of the nanoparticles can be easily inverted, avoiding intrinsic constraints of chemical methods.

  4. Determining iron oxide nanoparticle heating efficiency and elucidating local nanoparticle temperature for application in agarose gel-based tumor model.

    PubMed

    Shah, Rhythm R; Dombrowsky, Alexander R; Paulson, Abigail L; Johnson, Margaret P; Nikles, David E; Brazel, Christopher S

    2016-11-01

    Magnetic iron oxide nanoparticles (MNPs) have been developed for magnetic fluid hyperthermia (MFH) cancer therapy, where cancer cells are treated through the heat generated by application of a high frequency magnetic field. This heat has also been proposed as a mechanism to trigger release of chemotherapy agents. In each of these cases, MNPs with optimal heating performance can be used to maximize therapeutic effect while minimizing the required dosage of MNPs. In this study, the heating efficiencies (or specific absorption rate, SAR) of two types of MNPs were evaluated experimentally and then predicted from their magnetic properties. MNPs were also incorporated in the core of poly(ethylene glycol-b-caprolactone) micelles, co-localized with rhodamine B fluorescent dye attached to polycaprolactone to monitor local, nanoscale temperatures during magnetic heating. Despite a relatively high SAR produced by these MNPs, no significant temperature rise beyond that observed in the bulk solution was measured by fluorescence in the core of the magnetic micelles. MNPs were also incorporated into a macro-scale agarose gel system that mimicked a tumor targeted by MNPs and surrounded by healthy tissues. The agarose-based tumor models showed that targeted MNPs can reach hyperthermia temperatures inside a tumor with a sufficient MNP concentration, while causing minimal temperature rise in the healthy tissue surrounding the tumor. PMID:27523991

  5. Non-seeded synthesis and characterization of superparamagnetic iron oxide nanoparticles incorporated into silica nanoparticles via ultrasound.

    PubMed

    Sodipo, Bashiru Kayode; Abdul Aziz, Azlan

    2015-03-01

    A non-seeded method of incorporating superparamagnetic iron oxide nanoparticles (SPION) into silica nanoparticles is presented. Mixture of both SPION and silica nanoparticles was ultrasonically irradiated. The collapsed bubbles and shockwave generated from the ultrasonic irradiation produce tremendous force that caused inelastic collision and incorporation of SPION into the silica. Physicochemical analyses using transmission electron microscope (TEM), electronic spectroscopic imaging (ESI), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy demonstrated the formation of SPION/silica composite nanoparticles. The prepared composite nanoparticles exhibited superparamagnetic behaviour and nearly 70% of the initial saturation magnetization (Ms) of the SPION was retained. The presence and reactivity of the silica were demonstrated via assembling decanethiol monolayer on the composite nanoparticles. The silanol group of the silica provided the binding site for the alkyl group in the decanethiol molecules. Therefore, the thiol moiety became the terminal and functional group on the magnetic composite nanoparticles.

  6. Rapid Spectrophotometric Technique for Quantifying Iron in Cells Labeled with Superparamagnetic Iron Oxide Nanoparticles: Potential Translation to the Clinic

    PubMed Central

    Dadashzadeh, Esmaeel R.; Hobson, Matthew; Bryant, L. Henry; Dean, Dana D.; Frank, Joseph A.

    2012-01-01

    Labeling cells with superparamagnetic iron oxide (SPIO) nanoparticles provides the ability to track cells by Magnetic Resonance Imaging. Quantifying intracellular iron concentration in SPIO labeled cells would allow for the comparison of agents and techniques used to magnetically label cells. Here we describe a rapid spectrophotometric technique (ST) to quantify iron content of SPIO labeled cells, circumventing the previous requirement of an overnight acid digestion. Following lysis with 10% SDS of magnetically labeled cells, quantification of SPIO doped or labeled cells was performed using commonly available spectrophotometric instrument(s) by comparing absorptions at 370 and 750 nm with correction for turbidity of cellular products to determine iron content of each sample. Standard curves demonstrated high linear correlation (R2 = 0.998) between absorbance spectra of iron oxide nanoparticles and concentration in known SPIO doped cells. Comparisons of the ST to ICP-MS or NMR relaxometric (R2) determinations of intracellular iron contents in SPIO containing samples resulted in significant linear correlation between the techniques (R2 vs. ST, R2>0.992, p<0.0001, ST vs. ICP-MS, R2>0.995, p<0.0001) with the limit of detection of ST for iron = 0.66μg/ml. We have developed a rapid straightforward protocol that does not require overnight acid digestion for quantifying iron oxide content in magnetically labeled cells using readily available analytic instrumentation that should greatly expedite advances in comparing SPIO agents and protocols for labeling cells. PMID:23109392

  7. Intra- and interparticle magnetism of cobalt-doped iron-oxide nanoparticles encapsulated in a synthetic ferritin cage

    NASA Astrophysics Data System (ADS)

    Skoropata, E.; Desautels, R. D.; Falvo, E.; Ceci, P.; Kasyutich, O.; Freeland, J. W.; van Lierop, J.

    2014-11-01

    We present an in-depth examination of the composition and magnetism of cobalt (Co2 +)-doped iron-oxide nanoparticles encapsulated in Pyrococcus furiosus ferritin shells. We show that the Co2 + dopant ions were incorporated into the γ -Fe2O3/Fe3O4 core, with small paramagnetic-like clusters likely residing on the surface of the nanoparticle that were observed for all cobalt-doped samples. In addition, element-specific characterization using Mössbauer spectroscopy and polarized x-ray absorption indicated that Co2 + was incorporated exclusively into the octahedral B sites of the spinel-oxide nanoparticle. Comparable superparamagnetic blocking temperatures, coercivities, and effective anisotropies were obtained for 7%, 10%, and 12% cobalt-doped nanoparticles, and were only slightly reduced for 3% cobalt, indicating a strong effect of cobalt incorporation, with a lesser effect of cobalt content. Due to the regular particle size and separation that result from the use of the ferritin cage, a comparison of the effects of interparticle interactions on the disordered assembly of nanoparticles was also obtained that indicated significantly different behaviors between undoped and cobalt-doped nanoparticles.

  8. Poly(L-lysine)-modified iron oxide nanoparticles for stem cell labeling.

    PubMed

    Babic, Michal; Horák, Daniel; Trchová, Miroslava; Jendelová, Pavla; Glogarová, Katerina; Lesný, Petr; Herynek, Vít; Hájek, Milan; Syková, Eva

    2008-03-01

    New surface-modified iron oxide nanoparticles were developed by precipitation of Fe(II) and Fe(III) salts with ammonium hydroxide and oxidation of the resulting magnetite with sodium hypochlorite, followed by the addition of poly( L-lysine) (PLL) solution. PLL of several molecular weights ranging from 146 ( L-lysine) to 579 000 was tested as a coating to boost the intracellular uptake of the nanoparticles. The nanoparticles were characterized by TEM, dynamic light scattering, FTIR, and ultrasonic spectrometry. TEM revealed that the particles were ca. 6 nm in diameter, while FTIR showed that their surfaces were well-coated with PLL. The interaction of PLL-modified iron oxide nanoparticles with DMEM culture medium was verified by UV-vis spectroscopy. Rat bone marrow stromal cells (rMSCs) and human mesenchymal stem cells (hMSC) were labeled with PLL-modified iron oxide nanoparticles or with Endorem (control). Optical microscopy and TEM confirmed the presence of PLL-modified iron oxide nanoparticles inside the cells. Cellular uptake was very high (more than 92%) for PLL-modified nanoparticles that were coated with PLL (molecular weight 388 00) at a concentration of 0.02 mg PLL per milliliter of colloid. The cellular uptake of PLL-modified iron oxide was facilitated by its interaction with the negatively charged cell surface and subsequent endosomolytic uptake. The relaxivity of rMSCs labeled with PLL-modified iron oxide and the amount of iron in the cells were determined. PLL-modified iron oxide-labeled rMSCs were imaged in vitro and in vivo after intracerebral grafting into the contralateral hemisphere of the adult rat brain. The implanted cells were visible on magnetic resonance (MR) images as a hypointense area at the injection site and in the lesion. In comparison with Endorem, nanoparticles modified with PLL of an optimum molecular weight demonstrated a higher efficiency of intracellular uptake by MSC cells.

  9. Effect of radiation energy and intracellular iron dose on iron oxide nanoparticle enhancement of radiation cytotoxicity

    NASA Astrophysics Data System (ADS)

    Mazur, Courtney M.; Strawbridge, Rendall R.; Thompson, Ella S.; Petryk, Alicia A.; Gladstone, David J.; Hoopes, P. Jack

    2015-03-01

    Iron oxide nanoparticles (IONPs) are one of several high-Z materials currently being investigated for their ability to enhance the cytotoxic effects of therapeutic ionizing radiation. Studies with iron oxide, silver, gold, and hafnium oxide suggest radiation dose, radiation energy, cell type, and the type and level of metallic nanoparticle are all critical factors in achieving radiation enhancement in tumor cells. Using a single 4 Gy radiation dose, we compared the level of tumor cell cytotoxicity at two different intracellular iron concentrations and two different radiation energies in vitro. IONPs were added to cell culture media at concentrations of 0.25 mg Fe/mL and 1.0 mg Fe/mL and incubated with murine breast adenocarcinoma (MTG-B) cells for 72 hours. Extracellular iron was then removed and cells were irradiated at either 662 keV or 10 MV. At the 0.25 mg Fe/mL dose (4 pg Fe/cell), radiation energy did not affect the level of cytotoxicity. However with 1.0 mg Fe/mL (9 pg Fe/cell), the higher 10 MV radiation energy resulted in 50% greater cytotoxicity as compared to cells without IONPs irradiated at this energy. These results suggest IONPs may be able to significantly enhance the cytotoxic effects of radiation and improve therapeutic ratio if they can be selectively associated with cancer cells and/or tumors. Ongoing in vivo studies of IONP radiation enhancement in a murine tumor model are too immature to draw conclusions from at this time, however preliminary data suggests similar effectiveness of IONP radiation enhancement at 6 MV and 18 MV energy levels. In addition to the IONP-based radiation enhancement demonstrated here, the use of tumor-localized IONP with an externally delivered, non-toxic alternating magnetic field affords the opportunity to selectively heat and kill tumor cells. Combining IONP-based radiation sensitization and heat-based cytotoxicity provides a unique and potentially highly effective opportunity for therapeutic ratio enhancement.

  10. Film-Stabilizing Attributes of Polymeric Core-Shell Nanoparticles.

    PubMed

    Cai, Xiao-Jing; Yuan, Hao-Miao; Blencowe, Anton; Qiao, Greg G; Genzer, Jan; Spontak, Richard J

    2015-08-25

    Self-organization of nanoparticles into stable, molecularly thin films provides an insightful paradigm for manipulating the manner in which materials interact at nanoscale dimensions to generate unique material assemblies at macroscopic length scales. While prior studies in this vein have focused largely on examining the performance of inorganic or organic/inorganic hybrid nanoparticles (NPs), the present work examines the stabilizing attributes of fully organic core-shell microgel (CSMG) NPs composed of a cross-linked poly(ethylene glycol dimethacrylate) (PEGDMA) core and a shell of densely grafted, but relatively short-chain, polystyrene (PS) arms. Although PS homopolymer thin films measuring from a few to many nanometers in thickness, depending on the molecular weight, typically dewet rapidly from silica supports at elevated temperatures, spin-coated CSMG NP films measuring as thin as 10 nm remain stable under identical conditions for at least 72 h. Through the use of self-assembled monolayers (SAMs) to alter the surface of a flat silica-based support, we demonstrate that such stabilization is not attributable to hydrogen bonding between the acrylic core and silica. We also document that thin NP films consisting of three or less layers (10 nm) and deposited onto SAMs can be fully dissolved even after extensive thermal treatment, whereas slightly thicker films (40 nm) on Si wafer become only partially soluble during solvent rinsing with and without sonication. Taken together, these observations indicate that the present CSMG NP films are stabilized primarily by multidirectional penetration of relatively short, unentangled NP arms caused by NP layering, rather than by chain entanglement as in linear homopolymer thin films. This nanoscale "velcro"-like mechanism permits such NP films, unlike their homopolymer counterparts of comparable chain length and thickness, to remain intact as stable, free-floating sheets on water, and thus provides a viable alternative to

  11. Film-Stabilizing Attributes of Polymeric Core-Shell Nanoparticles.

    PubMed

    Cai, Xiao-Jing; Yuan, Hao-Miao; Blencowe, Anton; Qiao, Greg G; Genzer, Jan; Spontak, Richard J

    2015-08-25

    Self-organization of nanoparticles into stable, molecularly thin films provides an insightful paradigm for manipulating the manner in which materials interact at nanoscale dimensions to generate unique material assemblies at macroscopic length scales. While prior studies in this vein have focused largely on examining the performance of inorganic or organic/inorganic hybrid nanoparticles (NPs), the present work examines the stabilizing attributes of fully organic core-shell microgel (CSMG) NPs composed of a cross-linked poly(ethylene glycol dimethacrylate) (PEGDMA) core and a shell of densely grafted, but relatively short-chain, polystyrene (PS) arms. Although PS homopolymer thin films measuring from a few to many nanometers in thickness, depending on the molecular weight, typically dewet rapidly from silica supports at elevated temperatures, spin-coated CSMG NP films measuring as thin as 10 nm remain stable under identical conditions for at least 72 h. Through the use of self-assembled monolayers (SAMs) to alter the surface of a flat silica-based support, we demonstrate that such stabilization is not attributable to hydrogen bonding between the acrylic core and silica. We also document that thin NP films consisting of three or less layers (10 nm) and deposited onto SAMs can be fully dissolved even after extensive thermal treatment, whereas slightly thicker films (40 nm) on Si wafer become only partially soluble during solvent rinsing with and without sonication. Taken together, these observations indicate that the present CSMG NP films are stabilized primarily by multidirectional penetration of relatively short, unentangled NP arms caused by NP layering, rather than by chain entanglement as in linear homopolymer thin films. This nanoscale "velcro"-like mechanism permits such NP films, unlike their homopolymer counterparts of comparable chain length and thickness, to remain intact as stable, free-floating sheets on water, and thus provides a viable alternative to

  12. High-P,T Elasticity of Hcp Iron: Reinvestigation of the Applicability of Hcp Iron to the Earth's Inner Core

    NASA Astrophysics Data System (ADS)

    Tsuchiya, T.; Kawai, K.; Kuwayama, Y.; Ohsumi, M.; Ishii, M.

    2015-12-01

    Earth's inner core (329~364 GPa and 5000~6000 K) is thought to be composed of hexagonal closed pack (hcp) structured solid Fe-Ni alloy (e.g., Mao et al., 1998; Kuwayama et al., 2008; Sha & Cohen, 2010). Thermoelasticity of hcp (ɛ) iron is therefore a key to interpreting seismological information of the inner core: density, seismic wave velocities, and their anisotropy. However, several studies reported that hcp iron has a shear modulus distinctly larger than that of the inner core (e.g., Mao et al., 1998; Vocadlo et al., 2009). This large Poisson ratio of the inner core is one of the remaining inexplicable features of the deep Earth, and it suggests the presence of mechanisms to lower the S-wave velocity in the inner core, such as a low-velocity component (Prescher et al., 2015), pre-melting effect (Martorell et al., 2013), anelasticity, and so on. In this study, we perform ab initio molecular dynamics simulations employing a supercell larger than in previous calculations (Vocadlo et al., 2009; Martorell et al., 2013). Also computations are conducted in a wide P,T range including, but not limited to, the inner core conditions to clarify the P,T effects on the elasticity of the hcp iron more comprehensively, and to provide an internally-consistent thermoelastic model. In addition to checking the validity of the Birch's law, the obtained Poisson ratio and aggregate anisotropy, with and without the pre-melting effect, are compared against seismological constraints to reinvestigate the viability of hcp iron in the inner core. Research supported by KAKENHI (JSPS) and the X-ray Free Electron Laser Priority Strategy Program (MEXT).

  13. Cellular level loading and heating of superparamagnetic iron oxide nanoparticles.

    PubMed

    Kalambur, Venkat S; Longmire, Ellen K; Bischof, John C

    2007-11-20

    Superparamagnetic iron oxide nanoparticles (NPs) hold promise for a variety of biomedical applications due to their properties of visualization using magnetic resonance imaging (MRI), heating with radio frequency (rf), and movement in an external magnetic field. In this study, the cellular loading (uptake) mechanism of dextran- and surfactant-coated iron oxide NPs by malignant prostate tumor cells (LNCaP-Pro5) has been studied, and the feasibility of traditional rf treatment and a new laser heating method was evaluated. The kinetics of cell loading was quantified using magnetophoresis and a colorimetric assay. The results showed that loading of surfactant-coated iron oxide NPs with LNCaP-Pro5 was saturable with time (at 24 h) and extracellular concentration (11 pg Fe/cell at 0.5 mg Fe/mL), indicating that the particles are taken up by an "adsorptive endocytosis" pathway. Dextran-coated NPs, however, were taken up less efficiently (1 pg Fe/cell at 0.5 mg Fe/mL). Loading did not saturate with concentration suggesting uptake by fluid-phase endocytosis. Magnetophoresis suggests that NP-loaded cells can be held using external magnetic fields in microcirculatory flow velocities in vivo or in an appropriately designed extracorporeal circuit. Loaded cells were heated using traditional rf (260A, 357 kHz) and a new laser method (532 nm, 7 ns pulse duration, 0.03 J/pulse, 20 pulse/s). Iron oxide in water was found to absorb sufficiently strongly at 532 nm such that heating of individual NPs and thus loaded cells (1 pg Fe/cell) was effective (<10% cell survival) after 30 s of laser exposure. Radio frequency treatment required higher loading (>10 pg Fe/cell) and longer duration (30 min) when compared to laser to accomplish cell destruction (50% viability at 10 pg Fe/cell). Scaling calculations show that the pulsed laser method can lead to single-cell (loaded with NPs) treatments (200 degrees C temperature change at the surface of an individual NP) unlike traditional rf heating

  14. Hydrogen partitioning into molten iron at high pressure: implications for Earth's core

    PubMed

    Okuchi

    1997-12-01

    Because of dissolution of lighter elements such as sulfur, carbon, hydrogen, and oxygen, Earth's outer core is about 10 percent less dense than molten iron at the relevant pressure and temperature conditions. To determine whether hydrogen can account for a major part of the density deficit and is therefore an important constituent in the molten iron outer core, the hydrogen concentration in molten iron was measured at 7.5 gigapascals. From these measurements, the metal-silicate melt partitioning coefficient of hydrogen was determined as a function of temperature. If the magma ocean of primordial Earth was hydrous, more than 95 mole percent of H2O in this ocean should have reacted with iron to form FeHx, and about 60 percent of the density deficit is reconciled by adding hydrogen to the core. PMID:9388177

  15. Hf-W chronometry of core formation in planetesimals inferred from weakly irradiated iron meteorites

    NASA Astrophysics Data System (ADS)

    Kruijer, Thomas S.; Sprung, Peter; Kleine, Thorsten; Leya, Ingo; Burkhardt, Christoph; Wieler, Rainer

    2012-12-01

    The application of Hf-W chronometry to determine the timescales of core formation in the parent bodies of magmatic iron meteorites is severely hampered by 182W burnout during cosmic ray exposure of the parent meteoroids. Currently, no direct method exists to correct for the effects of 182W burnout, making the Hf-W ages for iron meteorites uncertain. Here we present noble gas and Hf-W isotope systematics of iron meteorite samples whose W isotopic compositions remained essentially unaffected by cosmic ray interactions. Most selected samples have concentrations of cosmogenic noble gases at or near the lowermost level observed in iron meteorites and, for iron meteorite standards, have very low noble gas and radionuclide based cosmic ray exposure ages (<60 Ma). In contrast to previous studies, no corrections of measured W isotope compositions are required for these iron meteorite samples. Their ɛ182W values (parts per 104 deviations from the terrestrial value) are higher than those measured for most other iron meteorites and range from -3.42 to -3.31, slightly elevated compared to the initial 182W/184W of Ca-Al-rich Inclusions (CAI; ɛ182W = -3.51 ± 0.10). The new W isotopic data indicate that core formation in the parent bodies of the IIAB, IIIAB, and IVA iron meteorites occurred ˜1-1.5 Myr after CAI formation (with an uncertainty of ˜1 Myr), consistent with earlier conclusions that the accretion and differentiation of iron meteorite parent bodies predated the accretion of most chondrite parent bodies. One ungrouped iron meteorite (Chinga) exhibits small nucleosynthetic W isotope anomalies, but after correction for these anomalies its ɛ182W value agrees with those of the other samples. Another ungrouped iron (Mbosi), however, has elevated ɛ182W relative to the other investigated irons, indicating metal-silicate separation ˜2-3 Myr later than in the parent bodies of the three major iron meteorite groups studied here.

  16. Plasmonics Resonance Enhanced Active Photothermal Effects of Aluminum and Iron Nanoparticles.

    PubMed

    Chong, Xinyuan; Abboud, Jacques; Zhang, Zhili

    2015-03-01

    Localized Surface Plasmonics Resonance (LSPR) enhanced active photothermal effects of both aluminum nanoparticles (Al NPs) and iron nanoparticles (Fe NPs) are experimentally observed. Photothermally activated motion and ignition by low-energy xenon flash are quantitatively measured. For nanoparticles of comparable sizes, photothermally activated motion height of Fe NPs is about 60% lower than that of Al NPs, while photothermal Minimum Ignition Energy (MIE) of Fe NPs is about 50% lower than that of Al NPs. Joule heating by LSPR enhanced photothermal effects among nanoparticles and subsequently triggered oxidation reactions are found responsible for the motion and ignition of the nanoparticles.

  17. Mesoscale modeling of functional properties in core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Mangeri, John; Heinonen, Olle; Karpeev, Dmitry; Nakhmanson, Serge

    2015-03-01

    Core-shell nanoparticle systems of Zn-ZnO and ZnO-TiO2 are studied computationally using the highly scalable MOOSE finite-element framework, developed at Idaho National Lab. The elastic anisotropic mismatch of the core and shell create an imprinting effect within the shell that produces a wide variation of strains. Due to this diversity of strains, the sharp band gap edges of the bulk semiconductor are observed to be ``thinned-out'' much like amorphous silicon. We show that a variety of factors, such as particle size, core-to-shell volume ratio, applied hydrostatic pressure, shell microstructure, as well as the effect of surface elasticity, can influence the distribution of optical band-gap values within the particle, which may prove useful within the field of photovoltaics. Part of the work by O.H. was supported by Award 70NANB14H012 from U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Material Design.

  18. Electrosprayed core-shell polymer-lipid nanoparticles for active component delivery

    NASA Astrophysics Data System (ADS)

    Eltayeb, Megdi; Stride, Eleanor; Edirisinghe, Mohan

    2013-11-01

    A key challenge in the production of multicomponent nanoparticles for healthcare applications is obtaining reproducible monodisperse nanoparticles with the minimum number of preparation steps. This paper focus on the use of electrohydrodynamic (EHD) techniques to produce core-shell polymer-lipid structures with a narrow size distribution in a single step process. These nanoparticles are composed of a hydrophilic core for active component encapsulation and a lipid shell. It was found that core-shell nanoparticles with a tunable size range between 30 and 90 nm and a narrow size distribution could be reproducibly manufactured. The results indicate that the lipid component (stearic acid) stabilizes the nanoparticles against collapse and aggregation and improves entrapment of active components, in this case vanillin, ethylmaltol and maltol. The overall structure of the nanoparticles produced was examined by multiple methods, including transmission electron microscopy and differential scanning calorimetry, to confirm that they were of core-shell form.

  19. Magnetic iron oxide nanoparticle functionalization: isocyanate moiety as a suitable monodentate anchoring group.

    PubMed

    Carrara, Claudio; Sala, Maria C; Caneva, Enrico; Cauteruccio, Silvia; Licandro, Emanuela

    2014-01-17

    A new strategy for anchoring organic molecules onto superparamagnetic iron oxide nanoparticles (SPIONs) using isocyanate containing linkers has been realized. This functional group easily and efficiently reacts with the hydroxyl residues of the nanoparticle surface, leading to the formation of a stable carbamate bond, as confirmed by means of spectroscopic and analytical data.

  20. RGD-conjugated iron oxide magnetic nanoparticles for magnetic resonance imaging contrast enhancement and hyperthermia.

    PubMed

    Zheng, S W; Huang, M; Hong, R Y; Deng, S M; Cheng, L F; Gao, B; Badami, D

    2014-03-01

    The purpose of this study was to develop a specific targeting magnetic nanoparticle probe for magnetic resonance imaging and therapy in the form of local hyperthermia. Carboxymethyl dextran-coated ultrasmall superparamagnetic iron oxide nanoparticles with carboxyl groups were coupled to cyclic arginine-glycine-aspartic peptides for integrin α(v)β₃ targeting. The particle size, magnetic properties, heating effect, and stability of the arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide were measured. The arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide demonstrates excellent stability and fast magneto-temperature response. Magnetic resonance imaging signal intensity of Bcap37 cells incubated with arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide was significantly decreased compared with that incubated with plain ultrasmall superparamagnetic iron oxide. The preferential uptake of arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide by target cells was further confirmed by Prussian blue staining and confocal laser scanning microscopy.

  1. VAPOR PHASE MERCURY SORPTION BY ORGANIC-SULFIDE COATED BIMETALLIC IRON-COPPER NANOPARTICLE AGGREGATES

    EPA Science Inventory

    Tetra sulfide silane coated iron-copper nano-particle aggregates are found to be potentially very high capacity sorbents for vapor phase mercury capture. High equilibrium capacities were obtained for the silane coated iron copper nano-aggregate sorbent at 70 oC and 120 oC. Even a...

  2. Iron Oxide Nanoparticles as a Potential Iron Fertilizer for Peanut (Arachis hypogaea)

    PubMed Central

    Rui, Mengmeng; Ma, Chuanxin; Hao, Yi; Guo, Jing; Rui, Yukui; Tang, Xinlian; Zhao, Qi; Fan, Xing; Zhang, Zetian; Hou, Tianqi; Zhu, Siyuan

    2016-01-01

    Nanomaterials are used in practically every aspect of modern life, including agriculture. The aim of this study was to evaluate the effectiveness of iron oxide nanoparticles (Fe2O3 NPs) as a fertilizer to replace traditional Fe fertilizers, which have various shortcomings. The effects of the Fe2O3 NPs and a chelated-Fe fertilizer (ethylenediaminetetraacetic acid-Fe; EDTA-Fe) fertilizer on the growth and development of peanut (Arachis hypogaea), a crop that is very sensitive to Fe deficiency, were studied in a pot experiment. The results showed that Fe2O3 NPs increased root length, plant height, biomass, and SPAD values of peanut plants. The Fe2O3 NPs promoted the growth of peanut by regulating phytohormone contents and antioxidant enzyme activity. The Fe contents in peanut plants with Fe2O3 NPs and EDTA-Fe treatments were higher than the control group. We used energy dispersive X-ray spectroscopy (EDS) to quantitatively analyze Fe in the soil. Peanut is usually cultivated in sandy soil, which is readily leached of fertilizers. However, the Fe2O3 NPs adsorbed onto sandy soil and improved the availability of Fe to the plants. Together, these results show that Fe2O3 NPs can replace traditional Fe fertilizers in the cultivation of peanut plants. To the best of our knowledge, this is the first research on the Fe2O3 NPs as the iron fertilizer. PMID:27375665

  3. Iron Oxide Nanoparticles as a Potential Iron Fertilizer for Peanut (Arachis hypogaea).

    PubMed

    Rui, Mengmeng; Ma, Chuanxin; Hao, Yi; Guo, Jing; Rui, Yukui; Tang, Xinlian; Zhao, Qi; Fan, Xing; Zhang, Zetian; Hou, Tianqi; Zhu, Siyuan

    2016-01-01

    Nanomaterials are used in practically every aspect of modern life, including agriculture. The aim of this study was to evaluate the effectiveness of iron oxide nanoparticles (Fe2O3 NPs) as a fertilizer to replace traditional Fe fertilizers, which have various shortcomings. The effects of the Fe2O3 NPs and a chelated-Fe fertilizer (ethylenediaminetetraacetic acid-Fe; EDTA-Fe) fertilizer on the growth and development of peanut (Arachis hypogaea), a crop that is very sensitive to Fe deficiency, were studied in a pot experiment. The results showed that Fe2O3 NPs increased root length, plant height, biomass, and SPAD values of peanut plants. The Fe2O3 NPs promoted the growth of peanut by regulating phytohormone contents and antioxidant enzyme activity. The Fe contents in peanut plants with Fe2O3 NPs and EDTA-Fe treatments were higher than the control group. We used energy dispersive X-ray spectroscopy (EDS) to quantitatively analyze Fe in the soil. Peanut is usually cultivated in sandy soil, which is readily leached of fertilizers. However, the Fe2O3 NPs adsorbed onto sandy soil and improved the availability of Fe to the plants. Together, these results show that Fe2O3 NPs can replace traditional Fe fertilizers in the cultivation of peanut plants. To the best of our knowledge, this is the first research on the Fe2O3 NPs as the iron fertilizer.

  4. Iron Oxide Nanoparticles as a Potential Iron Fertilizer for Peanut (Arachis hypogaea).

    PubMed

    Rui, Mengmeng; Ma, Chuanxin; Hao, Yi; Guo, Jing; Rui, Yukui; Tang, Xinlian; Zhao, Qi; Fan, Xing; Zhang, Zetian; Hou, Tianqi; Zhu, Siyuan

    2016-01-01

    Nanomaterials are used in practically every aspect of modern life, including agriculture. The aim of this study was to evaluate the effectiveness of iron oxide nanoparticles (Fe2O3 NPs) as a fertilizer to replace traditional Fe fertilizers, which have various shortcomings. The effects of the Fe2O3 NPs and a chelated-Fe fertilizer (ethylenediaminetetraacetic acid-Fe; EDTA-Fe) fertilizer on the growth and development of peanut (Arachis hypogaea), a crop that is very sensitive to Fe deficiency, were studied in a pot experiment. The results showed that Fe2O3 NPs increased root length, plant height, biomass, and SPAD values of peanut plants. The Fe2O3 NPs promoted the growth of peanut by regulating phytohormone contents and antioxidant enzyme activity. The Fe contents in peanut plants with Fe2O3 NPs and EDTA-Fe treatments were higher than the control group. We used energy dispersive X-ray spectroscopy (EDS) to quantitatively analyze Fe in the soil. Peanut is usually cultivated in sandy soil, which is readily leached of fertilizers. However, the Fe2O3 NPs adsorbed onto sandy soil and improved the availability of Fe to the plants. Together, these results show that Fe2O3 NPs can replace traditional Fe fertilizers in the cultivation of peanut plants. To the best of our knowledge, this is the first research on the Fe2O3 NPs as the iron fertilizer. PMID:27375665

  5. Preparation of human immune effector T cells containing iron-oxide nanoparticles.

    PubMed

    Iida, Hironori; Takayanagi, Kosuke; Nakanishi, Takuya; Kume, Akiko; Muramatsu, Kouji; Kiyohara, Yoshio; Akiyama, Yasuto; Osaka, Tetsuya

    2008-12-15

    Preparation of human immune T cells containing iron-oxide nanoparticles was carried out for the development of magnetically mediated immunotherapy. Peripheral blood lymphocytes (PBLs) after the incubation with magnetite nanoparticles were found to contain measurable ferric ions, which suggested the incorporation of magnetite nanoparticles. Transmission electron microscopic (TEM) study indicated that the incorporation of magnetite nanoparticles was mediated by endocytosis of PBLs. Furthermore, the effects of dosages and diameter of magnetite nanoparticles on the magnetite incorporation were investigated, and it was demonstrated that the increase in dosage promoted the incorporation of nanoparticles and the uptake into PBLs was more effective for magnetite nanoparticles, which formed smaller aggregations in medium. Finally, the demonstration of magnetite incorporation into enriched T cells and tumor antigen-specific cytotoxic T lymphocyte (CTL) line promises the achievement of magnetically mediated immunotherapy with tumor-specific CTLs containing magnetic nanoparticles.

  6. Novel method for the preparation of core-shell nanoparticles with movable Ag core and polystyrene loop shell

    SciTech Connect

    Liu Weijun; Zhang Zhicheng . E-mail: lwj3600@ustc.edu; He Weidong; Zheng Cheng; Ge Xuewu; Li, Jian; Liu Huarong; Jiang Hao

    2006-04-15

    Core/shell nanoparticles with movable silver (Ag) core and polystyrene (PSt) shell (Ag at PSt nanoparticle) were successfully synthesized at room temperature and under ambient pressure via two steps: {gamma}-irradiation and interfacial-initiated polymerization. Firstly, mono-dispersed Ag nanoparticles with diameters 20 nm were synthesized in inversed microemulsion by reducing silver nitrate under {gamma}-irradiation. Then, Ag nanoparticles were coated with PSt via interfacial-initiated polymerization with cumene hydroperoxide/ferrous sulfate/disodium ethylenediaminetetraacetate/sodium formaldehyde sulfoxylate (CHPO-Fe {sup 2+}-EDTA-SFS) as the redox initiation pair. The resulted Ag at PSt nanoparticles were identified by transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS)

  7. Magnetic Field-Induced Accentuation of Drug Release from Core/Shell Magnetic Mesoporous Silica Nanoparticles for Anticancer Treatment.

    PubMed

    Knezević Nikola Z

    2016-04-01

    Drug (9-aminoacridine) loaded core/shell magnetic iron oxide-containing mesoporous silica nanoparticles (MMSN) were treated with HeLa cells and the drug carriers were agitated by expo- sure to magnetic field. Viability studies show the applicability of drug loaded magnetic material for anticancer treatment, which is enhanced upon stimulation with magnetic field. Confocal micrographs of fluorescein grafted MMSN-treated HeLa cells confirmed the ability of magnetic field to concentrate the synthesized material in the exposed area of the cells. The synthesized material and the applied drug delivery method may find application in magnetic field-responsive targeted treatment of cancer. PMID:27451786

  8. Iron oxide nanoparticle hyperthermia and radiation cancer treatment

    NASA Astrophysics Data System (ADS)

    Cassim, S. M.; Giustini, A. J.; Petryk, A. A.; Strawbridge, R. A.; Hoopes, P. J.

    2009-02-01

    It is established that heat can enhance the effect of radiation cancer treatment. Due to the ability to localize thermal energy using nanoparticle hyperthermia, as opposed to other, less targeted, hyperthermia modalities, it appears such enhancement could be accomplished without complications normally associated with systemic or regional hyperthermia. This study employs non-curative (suboptimal), doses of heat and radiation, in an effort to determine the therapeutic enhancement potential for IONP hyperthermia and radiation. Methods: MTG-B murine breast adenocarcinoma cell are inoculated into the right flanks of female CH3/HEJ mice and grown to volumes of 150mm3+ /- 40 mm3. A single dose of 15 Gy (6 MeV) radiation was uniformly delivered to the tumor. A pre-defined thermal dose is delivered by direct injection of iron oxide nanoparticles into the tumor. By adjusting the field strength of the 160 KHz alternating magnetic field (AMF) an intra-tumoral temperature between 41.5 and 43 degrees Celsius was maintained for 10min. The alternating magnetic field was delivered by a water-cooled 36mm diameter square copper tube induction coil operating at 160 kHz with variable magnet field strengths up to 450 Oe . The primary endpoint of the study is the number of days required for the tumor to achieve a volume 3 fold greater than the volume at the time of treatment (tumor regrowth delay). Results: Preliminary results suggest the addition of a modest IONP hyperthermia to 15 Gy radiation achieved an approximate 50% increase in tumor regrowth delay as compared to a 15 Gy radiation treatment alone. The therapeutic effects of IONP heat and radiation combined were considered additive, however in mice that demonstrated complete response (no tumor present after 30 days), the effect was considered superadditive or synergistic. Although this data is very encouraging from a multimodality cancer therapy standpoint, additional temporal and dose related information is clearly necessary to

  9. Rheological characterization of a magnetorheological ferrofluid using iron nitride nanoparticles

    NASA Astrophysics Data System (ADS)

    Armijo, Leisha M.; Ahuré-Powell, Louise A.; Wereley, Norman M.

    2015-05-01

    Magnetorheology of a magnetorheological ferrofluid (MRFF) was investigated to study the role of a ferromagnetic nanoparticle (NP) additive in magnetorheological fluids (MRFs). Iron nitride (Fe16N2) NPs, nominally within the diameter range of ˜16-45 nm (spherical NPs) and ˜30-66 nm (cubic NPs), were coated with carboxy-polyethylene glycol (carboxy-PEG) and dispersed in silicone oil in order to produce a magnetic carrier fluid or ferrofluid for two solids loadings: 2 vol. % and 5 vol. %. Conventional spherical carbonyl iron (CI) particles, varying in diameter from 6 to 10 μm, were suspended in the ferrofluid at 25 vol. % solids loading. Rheological properties of the MRFF synthesized with the carboxy-PEG-based ferromagnetic carrier fluid were compared to the MRF synthesized with silicone oil to determine how ferrofluid can influence dynamic viscosity and yield stress. Rheological measurements of both MRF and MRFF samples were carried out using a Paar Physica 300 rheometer to estimate the field-off viscosity and to measure flow curves (i.e., shear stress vs. shear rate) as a function of magnetic field. A Bingham-plastic model was used to characterize the flow curves, and results show that there is an increase in the dynamic viscosity of the MRFF over the MRF. The ferromagnetic carrier fluid greatly increases yield stress as only 2 vol. % of added carboxy-PEG NPs improves the yield stress performance by almost 5%. A second MRFF sample synthesized with 5 vol. % of added carboxy-PEG NPs contained in the ferrofluid significantly enhanced the yield stress performance by 13% over the MRF at the same CI solids loading (25 vol. %).

  10. Synthesis of lithium iron phosphate/carbon microspheres by using polyacrylic acid coated iron phosphate nanoparticles derived from iron(III) acrylate.

    PubMed

    Xu, Dongwei; He, Yan-Bing; Chu, Xiaodong; Ding, Zhaojun; Li, Baohua; He, Jianfu; Du, Hongda; Qin, Xianying; Kang, Feiyu

    2015-03-01

    Lithium iron phosphate/carbon (LiFePO4 /C) microspheres with high rate and cycling performance are synthesized from iron phosphate/polyacrylic acid (FePO4 /PAA) nanoparticles. Iron(III) acrylate is used as a precursor for both the iron and carbon sources. FePO4 nanoparticles are first produced by a coprecipitation reaction. The byproduct, acrylic acid ions, is polymerized in situ to form a uniform PAA layer on the surface of the FePO4 nanoparticles. The as-prepared LiFePO4 /C microspheres are composed of primary nanoparticles with sizes of 40-50 nm. The nanoparticles are fully coated with a thin, uniform carbon layer derived from the decomposition of the PAA layer. The uniform carbon-coating layer cooperates with interstitial and boundary carbon derived from sucrose successfully to construct an excellent interconnecting conductive network in the microspheres. As a result of the unique structure, the as-prepared LiFePO4 /C microspheres display both high electronic and ionic conductivities, which contribute to their high rate performance (162.9 mAh g(-1) at 0.1C and 126.1 mAh g(-1) at 5C) and excellent cycling stability (97.1% of capacity retention after 500 cycles at 5C/5C). PMID:25469674

  11. Synthesis of lithium iron phosphate/carbon microspheres by using polyacrylic acid coated iron phosphate nanoparticles derived from iron(III) acrylate.

    PubMed

    Xu, Dongwei; He, Yan-Bing; Chu, Xiaodong; Ding, Zhaojun; Li, Baohua; He, Jianfu; Du, Hongda; Qin, Xianying; Kang, Feiyu

    2015-03-01

    Lithium iron phosphate/carbon (LiFePO4 /C) microspheres with high rate and cycling performance are synthesized from iron phosphate/polyacrylic acid (FePO4 /PAA) nanoparticles. Iron(III) acrylate is used as a precursor for both the iron and carbon sources. FePO4 nanoparticles are first produced by a coprecipitation reaction. The byproduct, acrylic acid ions, is polymerized in situ to form a uniform PAA layer on the surface of the FePO4 nanoparticles. The as-prepared LiFePO4 /C microspheres are composed of primary nanoparticles with sizes of 40-50 nm. The nanoparticles are fully coated with a thin, uniform carbon layer derived from the decomposition of the PAA layer. The uniform carbon-coating layer cooperates with interstitial and boundary carbon derived from sucrose successfully to construct an excellent interconnecting conductive network in the microspheres. As a result of the unique structure, the as-prepared LiFePO4 /C microspheres display both high electronic and ionic conductivities, which contribute to their high rate performance (162.9 mAh g(-1) at 0.1C and 126.1 mAh g(-1) at 5C) and excellent cycling stability (97.1% of capacity retention after 500 cycles at 5C/5C).

  12. Synthesis of phase-pure and monodisperse iron oxide nanoparticles by thermal decomposition

    SciTech Connect

    Hufschmid, Ryan D.; Arami, Hamed; Ferguson, R. Matthew; Gonzales, Marcela; Teeman, Eric M.; Brush, Lucien N.; Browning, Nigel D.; Krishnan, Kannan M.

    2015-06-03

    We present a comprehensive template for the design and synthesis of iron oxide nanoparticles with control over size, size distribution, phase, and resulting properties. Monodisperse superparamagnetic iron oxide nanoparticles were synthesized by thermal decomposition of three different iron containing precursors (iron oleate, iron pentacarbonyl, and iron oxyhydroxide) in organic solvents under a variety of synthetic conditions. We compare the suitability of these three kinetically controlled synthesis protocols, which have in common the use of iron oleate as a starting precursor or reaction intermediate, for producing nanoparticles with specific size and magnetic properties. Monodisperse particles were produced over a tunable range of sizes from approximately 2-30 nm. Reaction parameters such as precursor concentration, addition of surfactant, temperature, ramp rate, and time were adjusted to kinetically control size and size-distribution. In particular, large quantities of excess surfactant (up to 25:1 molar ratio) alter reaction kinetics and result in larger particles with uniform size; however, there is often a trade-off between large particles and a narrow size distribution. Iron oxide phase is also critical for establishing magnetic properties. As an example, we show the importance of obtaining the required iron oxide phase for application to Magnetic Particle Imaging (MPI), and describe how phase purity can be controlled.

  13. Dual drug loaded superparamagnetic iron oxide nanoparticles for targeted cancer therapy.

    PubMed

    Dilnawaz, Fahima; Singh, Abhalaxmi; Mohanty, Chandana; Sahoo, Sanjeeb K

    2010-05-01

    The primary inadequacy of chemotherapeutic drugs is their relative non-specificity and potential side effects to the healthy tissues. To overcome this, drug loaded multifunctional magnetic nanoparticles are conceptualized. We report here an aqueous based formulation of glycerol monooleate coated magnetic nanoparticles (GMO-MNPs) devoid of any surfactant capable of carrying high payload hydrophobic anticancer drugs. The biocompatibility was confirmed by tumor necrosis factor alpha assay, confocal microscopy. High entrapment efficiency approximately 95% and sustained release of encapsulated drugs for more than two weeks under in vitro conditions was achieved for different anticancer drugs (paclitaxel, rapamycin, alone or combination). Drug loaded GMO-MNPs did not affect the magnetization properties of the iron oxide core as confirmed by magnetization study. Additionally the MNPs were functionalized with carboxylic groups by coating with DMSA (Dimercaptosuccinic acid) for the supplementary conjugation of amines. For targeted therapy, HER2 antibody was conjugated to GMO-MNPs and showed enhanced uptake in human breast carcinoma cell line (MCF-7). The IC(50) doses revealed potential antiproliferative effect in MCF-7. Therefore, antibody conjugated GMO-MNPs could be used as potential drug carrier for the active therapeutic aspects in cancer therapy.

  14. Highly stable monodisperse PEGylated iron oxide nanoparticle aqueous suspensions: a nontoxic tracer for homogeneous magnetic bioassays.

    PubMed

    Lak, Aidin; Dieckhoff, Jan; Ludwig, Frank; Scholtyssek, Jan M; Goldmann, Oliver; Lünsdorf, Heinrich; Eberbeck, Dietmar; Kornowski, Andreas; Kraken, Mathias; Litterst, F J; Fiege, Kathrin; Mischnick, Petra; Schilling, Meinhard

    2013-12-01

    Uniformly sized and shaped iron oxide nanoparticles with a mean size of 25 nm were synthesized via decomposition of iron-oleate. High resolution transmission electron microscopy and Mössbauer spectroscopy investigations revealed that the particles are spheres primarily composed of Fe3O4 with a small fraction of FeO. From Mössbauer and static magnetization measurements, it was deduced that the particles are superparamagnetic at room temperature. The hydrophobic particles were successfully transferred into water via PEGylation using nitrodopamine as an anchoring group. IR spectroscopy and thermogravimetric analysis showed the success and efficiency of the phase transfer reaction. After PEGylation, the particles retained monodispersity and their magnetic core remained intact as proven by photon cross-correlation spectroscopy, ac susceptibility, and transmission electron microscopy. The particle aqueous suspensions revealed excellent water stability over a month of monitoring and also against temperature up to 40 °C. The particles exhibited a moderate cytotoxic effect on in vitro cultured bone marrow-derived macrophages and no release of inflammatory or anti-inflammatory cytokines. The PEGylated particles were functionalized with Herceptin antibodies via a conjugation chemistry, their response to a rotating magnetic field was studied using a fluxgate-based setup and was compared with the one recorded for hydrophobic and PEGylated particles. The particle phase lag rose after labeling with Herceptin, indicating the successful conjugation of Herceptin antibodies to the particles. PMID:24056778

  15. The influence of pH on iron speciation in podzol extracts: iron complexes with natural organic matter, and iron mineral nanoparticles.

    PubMed

    Neubauer, Elisabeth; Schenkeveld, Walter D C; Plathe, Kelly L; Rentenberger, Christian; von der Kammer, Frank; Kraemer, Stephan M; Hofmann, Thilo

    2013-09-01

    The quantities of natural organic matter (NOM) and associated iron (Fe) in soil extracts are known to increase with increasing extractant pH. However, it was unclear how the extraction pH affects Fe speciation for particles below 30 nm. We used flow field-flow fractionation (FlowFFF) and transmission electron microscopy (TEM) to investigate the association of Fe and trace elements with NOM and nanoparticulate iron (oxy)hydroxides in podzol extracts. For extracts prepared at the native soil pH (~4), and within a 1-30 nm size range, Fe was associated with NOM. In extracts with a pH≥7 from the E and B soil horizons, Fe was associated with NOM as well as with iron (oxy)hydroxide nanoparticles with a size of approximately 10 nm. The iron (oxy)hydroxide nanoparticles may have either formed within the soil extracts in response to the increase in pH, or they were mobilized from the soil. Additionally, pH shift experiments showed that iron (oxy)hydroxides formed when the native soil pH (~4) was increased to 9 following the extraction. The iron (oxy)hydroxide nanoparticles aggregated if the pH was decreased from 9 to 4. The speciation of Fe also influenced trace element speciation: lead was partly associated with the iron (oxy)hydroxides (when present), while copper binding to NOM remained unaffected by the presence of iron (oxy)hydroxide nanoparticles. The results of this study are important for interpreting the representativeness of soil extracts prepared at a pH other than the native soil pH, and for understanding the changes in Fe speciation that occur along a pH gradient.

  16. Superparamagnetic iron oxide/chitosan core/shells for hyperthermia application: Improved colloidal stability and biocompatibility

    NASA Astrophysics Data System (ADS)

    Patil, R. M.; Shete, P. B.; Thorat, N. D.; Otari, S. V.; Barick, K. C.; Prasad, A.; Ningthoujam, R. S.; Tiwale, B. M.; Pawar, S. H.

    2014-04-01

    Superparamagnetic magnetite nanoparticles are of great interest due to their potential biomedical applications. In the present investigation, Fe3O4 magnetic nanoparticles were prepared by alkaline precipitation using ferrous chloride as the sole source. An amphiphilic polyelectrolyte with the property of biocompatibility and functional carboxyl groups was used as a stabilizer to prepare a well-dispersed suspension of superparamagnetic Fe3O4 nanoparticles. The final material composed of Fe3O4 core and chitosan (CH) shell was produced. The amino groups of CH coated on Fe3O4 nanoparticles were further cross linked using glutaraldehyde (GLD) for stable coating. FTIR spectra, XPS and TGA confirmed the coating of CH/GLD on the surface of Fe3O4 nanoparticles. XRD patterns indicate the pure phase Fe3O4 with a spinel structure. The nanoparticles were superparamagnetic at room temperature with saturation magnetization values for bare and coated nanoparticles which were 51.68 emu/g and 48.60 emu/g, respectively. Zeta potential values showed higher colloidal stability of coated nanoparticles than the bare one. Cytotoxicity study up to 2 mg mL-1 concentration showed no drastic change in cell viability of nanoparticles after coating. Also, coated nanoparticles showed increased SAR value, making them suitable for hyperthermia therapy application.

  17. Induced Clustered Nanoconfinement of Superparamagnetic Iron Oxide in Biodegradable Nanoparticles Enhances Transverse Relaxivity for Targeted Theranostics

    PubMed Central

    Ragheb, Ragy R. T.; Kim, Dongin; Bandyopadhyay, Arunima; Chahboune, Halima; Bulutoglu, Beyza; Ezaldein, Harib; Criscione, Jason M.; Fahmy, Tarek M.

    2013-01-01

    Purpose Combined therapeutic and diagnostic agents, “theranostics” are emerging valuable tools for noninvasive imaging and drug delivery. Here, we report on a solid biodegradable multifunctional nanoparticle that combines both features. Methods Poly(lactide-co-glycolide) nanoparticles were engineered to confine superparamagnetic iron oxide contrast for magnetic resonance imaging while enabling controlled drug delivery and targeting to specific cells. To achieve this dual modality, fatty acids were used as anchors for surface ligands and for encapsulated iron oxide in the polymer matrix. Results We demonstrate that fatty acid modified iron oxide prolonged retention of the contrast agent in the polymer matrix during degradative release of drug. Antibody-fatty acid surface modification facilitated cellular targeting and subsequent internalization in cells while inducing clustering of encapsulated fatty-acid modified superparamagnetic iron oxide during particle formulation. This induced clustered confinement led to an aggregation within the nanoparticle and, hence, higher transverse relaxivity, r2, (294 mM−1 s−1) compared with nanoparticles without fatty-acid ligands (160 mM−1 s−1) and higher than commercially available superparamagnetic iron oxide nanoparticles (89 mM−1 s−1). Conclusion Clustering of superparamagnetic iron oxide in poly(lactide-co-glycolide) did not affect the controlled release of encapsulated drugs such as methotrexate or clodronate and their subsequent pharmacological activity, thus highlighting the full theranostic capability of our system. PMID:23401099

  18. Iron oxidation chemistry in ferritin. Increasing Fe/O2 stoichiometry during core formation.

    PubMed

    Xu, B; Chasteen, N D

    1991-10-25

    The origin of previously observed variations in stoichiometry of iron oxidation during the oxidative deposition of iron in ferritin has been poorly understood. Knowledge of the stoichiometry of Fe(II) oxidation by O2 is essential to establishing the mechanism of iron core formation. In the present work, the amount of Fe(II) oxidized was measured by Mössbauer spectrometry and the O2 consumed by mass spectrometry. The number of protons produced in the reaction was measured by "pH stat" titration and hydrogen peroxide production by the effect of the enzyme catalase on the measured stoichiometry. For protein samples containing low levels of iron (24 Fe(II)/protein) the stoichiometry was found to be 1.95 +/- 0.18 Fe(II)/O2 with H2O2 being a product, viz. Equation 1. 2Fe2+ + O2 + 4H2O----2FeOOH + H2O2 + 4H+ (1) EPR spin trapping experiments showed no evidence of superoxide radical formation. The stoichiometry markedly increased with additional iron (240-960 Fe/protein), to a value of 4 Fe(II)/O2 as in Equation 2. 4Fe2+ + O2 + 6H2O----4FeOOH + 8H+ (2) As the iron core is progressively laid down, the mechanism of iron oxidation changes from a protein dominated process with H2O2 being the primary product of O2 reduction to a mineral surface dominated process where H2O is the primary product. These results emphasize the importance of the apoferritin shell in facilitating iron oxidation in the early stage of iron deposition prior to significant development of the polynuclear iron core.

  19. Melting behavior of the iron-sulfur system and chemical convection in iron-rich planetary cores

    SciTech Connect

    Li, J.; Chen, B.

    2009-03-26

    We present experimental data on the high-pressure melting behavior of the Fe-S system from a synchrotron x-ray radiography study using the large volume press, with implications for the role of chemical convection in sulfur-bearing planetary cores. At present, Earth, Mercury and Ganymede are the only three solid bodies in the Solar System that possess intrinsic global magnetic fields. Dynamo simulation reveal that chemical buoyancy force associated with the formation of a solid inner core is critical for sustaining the Earth's magnetic field. Fluid motions in Mercury and Ganymede may be partially driven by chemical buoyancy force as well. The style of chemical convection and its influence on the thermal and chemical state and evolution of iron-rich cores are determined in part by the melting behavior of potential core-forming materials. Sulfur is widely accepted as a candidate light element in iron-rich planetary cores. In order to understand the role of chemical convection in sulfur-bearing cores, we studied the high-pressure melting behavior of Fe-S mixtures containing 9 wt% sulfur using the synchrotron x-ray radiographic method in a large volume press.

  20. Defective iron-oxide nanoparticles synthesised by high temperature plasma processing: a magnetic characterisation versus temperature.

    PubMed

    Balasubramanian, C; Joseph, B; Orpe, P B; Saini, N L; Mukherjee, S; Dziedzic-Kocurek, K; Stanek, J; Di Gioacchino, D; Marcelli, A

    2016-11-01

    Magnetic properties and phase compositions of iron-oxide nanoparticles synthesised by a high temperature arc plasma route have been investigated by Mössbauer spectroscopy and high harmonic magnetic AC susceptibility measurements, and correlated with morphological and structural properties for different synthesis conditions. The Mössbauer spectra precisely determined the presence of different iron-oxide fractions in the investigated nanoparticles, while the high harmonic magnetic susceptibility measurements revealed the occurrence of metastable magnetic phases evolving in temperature and time. This study illustrates magnetic properties and dynamics of the magnetic configurations of iron-oxide nanoparticles grown by high temperature plasma, a process less explored so far but extremely useful for synthesising large numbers of nanoparticles for industrial applications. PMID:27668803

  1. Defective iron-oxide nanoparticles synthesised by high temperature plasma processing: a magnetic characterisation versus temperature.

    PubMed

    Balasubramanian, C; Joseph, B; Orpe, P B; Saini, N L; Mukherjee, S; Dziedzic-Kocurek, K; Stanek, J; Di Gioacchino, D; Marcelli, A

    2016-11-01

    Magnetic properties and phase compositions of iron-oxide nanoparticles synthesised by a high temperature arc plasma route have been investigated by Mössbauer spectroscopy and high harmonic magnetic AC susceptibility measurements, and correlated with morphological and structural properties for different synthesis conditions. The Mössbauer spectra precisely determined the presence of different iron-oxide fractions in the investigated nanoparticles, while the high harmonic magnetic susceptibility measurements revealed the occurrence of metastable magnetic phases evolving in temperature and time. This study illustrates magnetic properties and dynamics of the magnetic configurations of iron-oxide nanoparticles grown by high temperature plasma, a process less explored so far but extremely useful for synthesising large numbers of nanoparticles for industrial applications.

  2. Microwave Absorption Properties of Iron Nanoparticles Prepared by Ball-Milling

    NASA Astrophysics Data System (ADS)

    Chu, Xuan T. A.; Ta, Bach N.; Ngo, Le T. H.; Do, Manh H.; Nguyen, Phuc X.; Nam, Dao N. H.

    2016-05-01

    A nanopowder of iron was prepared using a high-energy ball milling method, which is capable of producing nanoparticles at a reasonably larger scale compared to conventional chemical methods. Analyses using x-ray diffraction and magnetic measurements indicate that the iron nanoparticles are a single phase of a body-centered cubic structure and have quite stable magnetic characteristics in the air. The iron nanoparticles were then mixed with paraffin and pressed into flat square plates for free-space microwave transmission and reflection measurements in the 4-8 GHz range. Without an Al backing plate, the Fe nanoparticles seem to only weakly absorb microwave radiation. The reflected signal S 11 drops to zero and a very large negative value of reflection loss ( RL) are observed for Al-backed samples, suggesting the existence of a phase matching resonance near frequency f ˜ 6 GHz.

  3. Defective iron-oxide nanoparticles synthesised by high temperature plasma processing: a magnetic characterisation versus temperature

    NASA Astrophysics Data System (ADS)

    Balasubramanian, C.; Joseph, B.; Orpe, PB; Saini, NL; Mukherjee, S.; Dziedzic-Kocurek, K.; Stanek, J.; Di Gioacchino, D.; Marcelli, A.

    2016-11-01

    Magnetic properties and phase compositions of iron-oxide nanoparticles synthesised by a high temperature arc plasma route have been investigated by Mössbauer spectroscopy and high harmonic magnetic AC susceptibility measurements, and correlated with morphological and structural properties for different synthesis conditions. The Mössbauer spectra precisely determined the presence of different iron-oxide fractions in the investigated nanoparticles, while the high harmonic magnetic susceptibility measurements revealed the occurrence of metastable magnetic phases evolving in temperature and time. This study illustrates magnetic properties and dynamics of the magnetic configurations of iron-oxide nanoparticles grown by high temperature plasma, a process less explored so far but extremely useful for synthesising large numbers of nanoparticles for industrial applications.

  4. Magnetic resonance imaging of microvessels using iron-oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Olamaei, N.; Cheriet, F.; Martel, S.

    2013-03-01

    The visualization of microstructures including blood vessels with an inner overall cross-sectional area below approximately 200 μm remains beyond the capabilities of current clinical imaging modalities. But with magnetic resonance (MR) imaging, magnetic entities cause susceptibility artifacts in the images by disrupting the homogeneous magnetic field in a much larger scale than their actual size. As validated in this paper through simulation and in-vitro experiments, these artifacts can serve as a source of contrast, enabling microvessels with an inner diameter below the spatial resolution of any medical imaging modalities to be visualized using a clinical MR scanner. For such experiments, micron-sized agglomerations of iron-oxide (Fe3O4) nanoparticles were injected in microchannels with internal diameters of 200 and 50 μm equivalent to a narrower artery or a larger arteriole, and down to a smaller arteriole, respectively. The results show the feasibility of the proposed method for micro-particle detection and the visualization of microvessels using a 1.5 T clinical MR scanner. It was confirmed that the method is reproducible and accurate at the sub-pixel level.

  5. Superparamagnetic iron oxide nanoparticles regulate smooth muscle cell phenotype

    PubMed Central

    Angelopoulos, Ioannis; Southern, Paul; Pankhurst, Quentin A.

    2016-01-01

    Abstract Superparamagnetic iron oxide nanoparticles (SPION) are used for an increasing range of biomedical applications, from imaging to mechanical actuation of cells and tissue. The aim of this study was to investigate the loading of smooth muscle cells (SMC) with SPION and to explore what effect this has on the phenotype of the cells. Adherent human SMC were loaded with ∼17 pg of unconjugated, negatively charged, 50 nm SPION. Clusters of the internalized SPION particles were held in discrete cytoplasmic vesicles. Internalized SPION did not cause any change in cell morphology, proliferation, metabolic activity, or staining pattern of actin and calponin, two of the muscle contractile proteins involved in force generation. However, internalized SPION inhibited the increased gene expression of actin and calponin normally observed when cells are incubated under differentiation conditions. The observed change in the control of gene expression of muscle contractile apparatus by SPION has not previously been described. This finding could offer novel approaches for regulating the phenotype of SMC and warrants further investigation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2412–2419, 2016. PMID:27176658

  6. Synthesis and cytotoxicity study of magnesium ferrite-gold core-shell nanoparticles.

    PubMed

    Nonkumwong, Jeeranan; Pakawanit, Phakkhananan; Wipatanawin, Angkana; Jantaratana, Pongsakorn; Ananta, Supon; Srisombat, Laongnuan

    2016-04-01

    In this work, the core-magnesium ferrite (MgFe2O4) nanoparticles were prepared by hydrothermal technique. Completed gold (Au) shell coating on the surfaces of MgFe2O4 nanoparticles was obtained by varying core/shell ratios via a reduction method. Phase identification, morphological evolution, optical properties, magnetic properties and cytotoxicity to mammalian cells of these MgFe2O4 core coated with Au nanoparticles were examined by using a combination of X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy, UV-visible spectroscopy (UV-vis), vibrating sample magnetometry and resazurin microplate assay techniques. In general, TEM images revealed different sizes of the core-shell nanoparticles generated from various core/shell ratios and confirmed the completed Au shell coating on MgFe2O4 core nanoparticles via suitable core/shell ratio with particle size less than 100 nm. The core-shell nanoparticle size and the quality of coating influence the optical properties of the products. The UV-vis spectra of complete coated MgFe2O4-Au core-shell nanoparticles exhibit the absorption bands in the near-Infrared (NIR) region indicating high potential for therapeutic applications. Based on the magnetic property measurement, it was found that the obtained MgFe2O4-Au core-shell nanoparticles still exhibit superparamagnetism with lower saturation magnetization value, compared with MgFe2O4 core. Both of MgFe2O4 and MgFe2O4-Au core-shell also showed in vitro non-cytotoxicity to mouse areola fibroblast (L-929) cell line.

  7. Multifunctional superparamagnetic iron oxide nanoparticles for combined chemotherapy and hyperthermia cancer treatment

    NASA Astrophysics Data System (ADS)

    Quinto, Christopher A.; Mohindra, Priya; Tong, Sheng; Bao, Gang

    2015-07-01

    Superparamagnetic iron oxide (SPIO) nanoparticles have the potential for use as a multimodal cancer therapy agent due to their ability to carry anticancer drugs and generate localized heat when exposed to an alternating magnetic field, resulting in combined chemotherapy and hyperthermia. To explore this potential, we synthesized SPIOs with a phospholipid-polyethylene glycol (PEG) coating, and loaded Doxorubicin (DOX) with a 30.8% w/w loading capacity when the PEG length is optimized. We found that DOX-loaded SPIOs exhibited a sustained DOX release over 72 hours where the release kinetics could be altered by the PEG length. In contrast, the heating efficiency of the SPIOs showed minimal change with the PEG length. With a core size of 14 nm, the SPIOs could generate sufficient heat to raise the local temperature to 43 °C, sufficient to trigger apoptosis in cancer cells. Further, we found that DOX-loaded SPIOs resulted in cell death comparable to free DOX, and that the combined effect of DOX and SPIO-induced hyperthermia enhanced cancer cell death in vitro. This study demonstrates the potential of using phospholipid-PEG coated SPIOs for chemotherapy-hyperthermia combinatorial cancer treatment with increased efficacy.Superparamagnetic iron oxide (SPIO) nanoparticles have the potential for use as a multimodal cancer therapy agent due to their ability to carry anticancer drugs and generate localized heat when exposed to an alternating magnetic field, resulting in combined chemotherapy and hyperthermia. To explore this potential, we synthesized SPIOs with a phospholipid-polyethylene glycol (PEG) coating, and loaded Doxorubicin (DOX) with a 30.8% w/w loading capacity when the PEG length is optimized. We found that DOX-loaded SPIOs exhibited a sustained DOX release over 72 hours where the release kinetics could be altered by the PEG length. In contrast, the heating efficiency of the SPIOs showed minimal change with the PEG length. With a core size of 14 nm, the SPIOs could

  8. Mitochondrial iron accumulation exacerbates hepatic toxicity caused by hepatitis C virus core protein

    SciTech Connect

    Sekine, Shuichi; Ito, Konomi; Watanabe, Haruna; Nakano, Takafumi; Moriya, Kyoji; Shintani, Yoshizumi; Fujie, Hajime; Tsutsumi, Takeya; Miyoshi, Hideyuki; Fujinaga, Hidetake; Shinzawa, Seiko; Koike, Kazuhiko; Horie, Toshiharu

    2015-02-01

    Patients with long-lasting hepatitis C virus (HCV) infection are at major risk of hepatocellular carcinoma (HCC). Iron accumulation in the livers of these patients is thought to exacerbate conditions of oxidative stress. Transgenic mice that express the HCV core protein develop HCC after the steatosis stage and produce an excess of hepatic reactive oxygen species (ROS). The overproduction of ROS in the liver is the net result of HCV core protein-induced dysfunction of the mitochondrial respiratory chain. This study examined the impact of ferric nitrilacetic acid (Fe-NTA)-mediated iron overload on mitochondrial damage and ROS production in HCV core protein-expressing HepG2 (human HCC) cells (Hep39b cells). A decrease in mitochondrial membrane potential and ROS production were observed following Fe-NTA treatment. After continuous exposure to Fe-NTA for six days, cell toxicity was observed in Hep39b cells, but not in mock (vector-transfected) HepG2 cells. Moreover, mitochondrial iron ({sup 59}Fe) uptake was increased in the livers of HCV core protein-expressing transgenic mice. This increase in mitochondrial iron uptake was inhibited by Ru360, a mitochondrial Ca{sup 2+} uniporter inhibitor. Furthermore, the Fe-NTA-induced augmentation of mitochondrial dysfunction, ROS production, and cell toxicity were also inhibited by Ru360 in Hep39b cells. Taken together, these results indicate that Ca{sup 2+} uniporter-mediated mitochondrial accumulation of iron exacerbates hepatocyte toxicity caused by the HCV core protein. - Highlights: • Iron accumulation in the livers of patients with hepatitis C virus (HCV) infection is thought to exacerbate oxidative stress. • The impact of iron overload on mitochondrial damage and ROS production in HCV core protein-expressing cells were examined. • Mitochondrial iron uptake was increased in the livers of HCV core protein-expressing transgenic mice. • Ca{sup 2+} uniporter-mediated mitochondrial accumulation of iron exacerbates

  9. Body-centered cubic iron-nickel alloy in Earth's core.

    PubMed

    Dubrovinsky, L; Dubrovinskaia, N; Narygina, O; Kantor, I; Kuznetzov, A; Prakapenka, V B; Vitos, L; Johansson, B; Mikhaylushkin, A S; Simak, S I; Abrikosov, I A

    2007-06-29

    Cosmochemical, geochemical, and geophysical studies provide evidence that Earth's core contains iron with substantial (5 to 15%) amounts of nickel. The iron-nickel alloy Fe(0.9)Ni(0.1) has been studied in situ by means of angle-dispersive x-ray diffraction in internally heated diamond anvil cells (DACs), and its resistance has been measured as a function of pressure and temperature. At pressures above 225 gigapascals and temperatures over 3400 kelvin, Fe(0.9)Ni(0.1) adopts a body-centered cubic structure. Our experimental and theoretical results not only support the interpretation of shockwave data on pure iron as showing a solid-solid phase transition above about 200 gigapascals, but also suggest that iron alloys with geochemically reasonable compositions (that is, with substantial nickel, sulfur, or silicon content) adopt the bcc structure in Earth's inner core.

  10. Body-Centered Cubic Iron-Nickel Alloy in Earth's Core

    SciTech Connect

    Dubrovinsky, L; Dubrovinskaia, N; Narygina, O; Kantor, I; Kuznetzov, A; Prakapenka, V B; Vitos, L; Johansson, B; Mikhaylushkin, A S; Simak, S I; Abrikosov, I A

    2012-04-17

    Cosmochemical, geochemical, and geophysical studies provide evidence that Earth's core contains iron with substantial (5 to 15%) amounts of nickel. The iron-nickel alloy Fe0.9Ni0.1 has been studied in situ by means of angle-dispersive x-ray diffraction in internally heated diamond anvil cells (DACs), and its resistance has been measured as a function of pressure and temperature. At pressures above 225 gigapascals and temperatures over 3400 kelvin, Fe0.9Ni0.1 adopts a body-centered cubic structure. Our experimental and theoretical results not only support the interpretation of shockwave data on pure iron as showing a solid-solid phase transition above about 200 gigapascals, but also suggest that iron alloys with geochemically reasonable compositions (that is, with substantial nickel, sulfur, or silicon content) adopt the bcc structure in Earth's inner core.

  11. Establishing the Structural Integrity of Core-Shell Nanoparticles against Elemental Migration using Luminescent Lanthanide Probes.

    PubMed

    Chen, Bing; Peng, Dengfeng; Chen, Xian; Qiao, Xvsheng; Fan, Xianping; Wang, Feng

    2015-10-19

    Core-shell structured nanoparticles are increasingly used to host luminescent lanthanide ions but the structural integrity of these nanoparticles still lacks sufficient understanding. Herein, we present a new approach to detect the diffusion of dopant ions in core-shell nanostructures using luminescent lanthanide probes whose emission profile and luminescence lifetime are sensitive to the chemical environment. We show that dopant ions in solution-synthesized core-shell nanoparticles are firmly confined in the designed locations. However, annealing at certain temperatures (greater than circa 350 °C) promotes diffusion of the dopant ions and leads to degradation of the integrity of the nanoparticles. These insights into core-shell nanostructures should enhance our ability to understand and use lanthanide-doped luminescent nanoparticles.

  12. Synthesis and in vitro cellular interactions of superparamagnetic iron nanoparticles with a crystalline gold shell

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, Sulalit; Singh, Gurvinder; Sandvig, Ioanna; Sandvig, Axel; Mathieu, Roland; Anil Kumar, P.; Glomm, Wilhelm Robert

    2014-10-01

    Fe@Au core-shell nanoparticles (NPs) exhibit multiple functionalities enabling their effective use in applications such as medical imaging and drug delivery. In this work, a novel synthetic method was developed and optimized for the synthesis of highly stable, monodisperse Fe@Au NPs of average diameter ∼24 nm exhibiting magneto-plasmonic characteristics. Fe@Au NPs were characterized by a wide range of experimental techniques, including scanning (transmission) electron microscopy (S(T)EM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS) and UV-vis spectroscopy. The formed particles comprise an amorphous iron core with a crystalline Au shell of tunable thickness, and retain the superparamagnetic properties at room temperature after formation of a crystalline Au shell. After surface modification, PEGylated Fe@Au NPs were used for in vitro studies on olfactory ensheathing cells (OECs) and human neural stem cells (hNSCs). No adverse effects of the Fe@Au particles were observed post-labeling, both cell types retaining normal morphology, viability, proliferation, and motility. It can be concluded that no appreciable toxic effects on both cell types, coupled with multifunctionality and chemical stability make them ideal candidates for therapeutic as well as diagnostic applications.

  13. Plasma Position Measurements in a Tokamak with an Iron Core Transformer

    NASA Astrophysics Data System (ADS)

    Kwon, Gi-Chung; Choe, W.; Kim, Jayhyun; Yi, Hyo-Suk; Jeon, Sang-Jean; Huh, Songwhe; Chang, Hong-Young; Choi, Duk-In

    2000-07-01

    Two simple methods of estimating the plasma position in a large-aspect-ratio, low-βp tokamak with an iron core transformer are demonstrated: a magnetic diagnostic method and an optical method. The magnetic diagnostic method utilizes an array of magnetic pickup coils to measure the poloidal magnetic field produced by the plasma current. To include the effects of toroidicity and an iron core transformer, the correction factor was calculated with the magnetic material (or iron core) inside the calculation domain and incorporated in the analysis. The evolution of horizontal and vertical displacement of the plasma center obtained in this way is used to control the KAIST-Tokamak plasmas. To compare the plasma position estimated using the magnetic pickup coils, a simple optical method is also demonstrated on KAIST-TOKAMAK using a composite video signal from a charge-coupled device (CCD) camera. The two results are in good agreement.

  14. The iron-sulfur core in Rieske proteins is not symmetric.

    PubMed

    Ali, Md Ehesan; Nair, Nisanth N; Retegan, Marius; Neese, Frank; Staemmler, Volker; Marx, Dominik

    2014-12-01

    At variance with ferredoxins, Rieske-type proteins contain a chemically asymmetric iron-sulfur cluster. Nevertheless, X-ray crystallography apparently finds their [2Fe-2S] cores to be structurally symmetric or very close to symmetric (i.e. the four iron-sulfur bonds in the [2Fe-2S] core are equidistant). Using a combination of advanced density-based approaches, including finite-temperature molecular dynamics to access thermal fluctuations and free-energy profiles, in conjunction with correlated wavefunction-based methods we clearly predict an asymmetric core structure. This reveals a fundamental and intrinsic difference within the iron-sulfur clusters hosted by Rieske proteins and ferredoxins and thus opens up a new dimension for the ongoing efforts in understanding the role of Rieske-type [2Fe-2S] cluster in electron transfer processes that occur in almost all biological systems.

  15. Carbon-coated iron oxide nanoparticles as contrast agents in magnetic resonance imaging.

    PubMed

    Bae, Hongsub; Ahmad, Tanveer; Rhee, Ilsu; Chang, Yongmin; Jin, Seong-Uk; Hong, Sungwook

    2012-01-01

    Coprecipitated ferrite nanoparticles were coated with carbon using a hydrothermal method. From transmission electron microscope pictures, we could see that the coated iron oxide nanoparticles were spherical in shape with an average diameter of 90 nm. The strong bonding of carbon on the nanoparticle surfaces was checked by noting the C = O and C = C vibrations in Fourier transform infrared spectra. The spin-lattice relaxation process [T1] and spin-spin relaxation process [T2] relaxivities of hydrogen protons in the aqueous solution of coated nanoparticles were determined to be 1.139 (mM·s)-1 and 1.115 (mM·s)-1, respectively. These results showed that the carbon-coated iron oxide nanoparticles are applicable as both T1 and T2 contrast agents in magnetic resonance imaging.PACS: 81.05.y; 76.60.Es; 61.46; 75.50.k; 87.61.

  16. Study of carbonyl iron/poly(butylcyanoacrylate) (core/shell) particles as anticancer drug delivery systems Loading and release properties.

    PubMed

    Arias, José L; Linares-Molinero, Fernando; Gallardo, Visitación; Delgado, Angel V

    2008-03-01

    The aim of this study is to develop a detailed investigation of the capabilities of carbonyl iron/poly(butylcyanoacrylate) (core/shell) particles for the loading and release of 5-Fluorouracil and Ftorafur. The anionic polymerization procedure, used to obtain poly(alkylcyanoacrylate) nanoparticles for drug delivery, was followed in the synthesis of the composite particles, except that the polymerization medium was a carbonyl iron suspension. The influence of the two mechanisms of drug incorporation (entrapment in the polymeric network and surface adsorption) on the drug loading and release profiles were investigated by means of spectrophotometric and electrophoretic measurements. The optimum loading conditions were ascertained and used to perform drug release evaluations. Among the factors affecting drug loading, both pH and drug concentration were found to be the main determining ones. For both drugs, the release profile was found to be biphasic, since the drug adsorbed on the surface was released rather rapidly (close to 100% in 1h), whereas the drug incorporated in the polymer matrix required between 10 and 20h to be fully released. The kinetics of the drug release from the core/shell particles was mainly controlled by the pH of the release medium, the type of drug incorporation, and the amount of drug loaded.

  17. Shape-Controlled Synthesis of Magnetic Iron Oxide@SiO₂-Au@C Particles with Core-Shell Nanostructures.

    PubMed

    Li, Mo; Li, Xiangcun; Qi, Xinhong; Luo, Fan; He, Gaohong

    2015-05-12

    The preparation of nonspherical magnetic core-shell nanostructures with uniform sizes still remains a challenge. In this study, magnetic iron oxide@SiO2-Au@C particles with different shapes, such as pseduocube, ellipsoid, and peanut, were synthesized using hematite as templates and precursors of magnetic iron oxide. The as-obtained magnetic particles demonstrated uniform sizes, shapes, and well-designed core-shell nanostructures. Transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX) analysis showed that the Au nanoparticles (AuNPs) of ∼6 nm were uniformly distributed between the silica and carbon layers. The embedding of the metal nanocrystals into the two different layers prevented the aggregation and reduced the loss of the metal nanocrystals during recycling. Catalytic performance of the peanut-like particles kept almost unchanged without a noticeable decrease in the reduction of 4-nitrophenol (4-NP) in 8 min even after 7 cycles, indicating excellent reusability of the particles. Moreover, the catalyst could be readily recycled magnetically after each reduction by an external magnetic field.

  18. Block Copolymer Cross-linked Nanoassemblies Improve Particle Stability and Biocompatibility of Superparamagnetic Iron Oxide Nanoparticles

    PubMed Central

    Dan, Mo; Scott, Daniel F.; Hardy, Peter A.; Wydra, Robert J.; Hilt, J. Zach; Yokel, Robert A.; Bae, Younsoo

    2014-01-01

    Purpose To develop cross-linked nanoassemblies (CNAs) as carriers for superparamagnetic iron oxide nanoparticles (IONPs). Methods Ferric and ferrous ions were co-precipitated inside core-shell type nanoparticles prepared by cross-linking poly(ethylene glycol)-poly(aspartate) block copolymers to prepare CNAs entrapping Fe3O4 IONPs (CNA-IONPs). Particle stability and biocompatibility of CNA-IONPs were characterized in comparison to citrate-coated Fe3O4 IONPs (Citrate-IONPs). Results CNA-IONPs, approximately 30 nm in diameter, showed no precipitation in water, PBS, or a cell culture medium after 3 or 30 h, at 22, 37, and 43 °C, and 1, 2.5, and 5 mg/mL, whereas Citrate-IONPs agglomerated rapidly (> 400 nm) in all aqueous media tested. No cytotoxicity was observed in a mouse brain endothelial-derived cell line (bEnd.3) exposed to CNA-IONPs up to 10 mg/mL for 30 h. Citrate-IONPs (> 0.05 mg/mL) reduced cell viability after 3 h. CNA-IONPs retained the superparamagnetic properties of entrapped IONPs, enhancing T2-weighted magnetic resonance images (MRI) at 0.02 mg/mL, and generating heat at a mild hyperthermic level (40 ~ 42 °C) with an alternating magnetic field (AMF). Conclusion Compared to citric acid coating, CNAs with a cross-linked anionic core improved particle stability and biocompatibility of IONPs, which would be beneficial for future MRI and AMF-induced remote hyperthermia applications. PMID:23080062

  19. Size-controlled synthesis of thermal stable single-cored Ru@H-SiO2 core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Yu, Xiaolong; Yu, Hongbo; Lim, Zi-Yian; Yang, Guangming; Xie, Zhaohui; Zhou, Shenghu; Yin, Hongfeng

    2016-06-01

    Single-cored Ru@H-SiO2 (H: hollow) core-shell nanoparticles (NPs) with around 4.3 nm Ru cores and hollow SiO2 shells were prepared successfully. In this synthetic process, we obtained multi-cored Ru@SiO2 NPs initially, single-cored RuO2@H-SiO2 NPs during treatment, and single-cored Ru@H-SiO2 NPs in the end. The Ru@SiO2 NPs were prepared by water-in-oil microemulsion method, and the size and core number of Ru@SiO2 NPs can be controlled. Single-cored RuO2@H-SiO2 NPs and Ru@H-SiO2 NPs were successively obtained by calcination and reduction. The structure showed promising aggregate-resistant performance and potential application in catalysis.

  20. Compact Ag@Fe3O4 Core-shell Nanoparticles by Means of Single-step Thermal Decomposition Reaction

    NASA Astrophysics Data System (ADS)

    Brollo, Maria Eugênia F.; López-Ruiz, Román; Muraca, Diego; Figueroa, Santiago J. A.; Pirota, Kleber R.; Knobel, Marcelo

    2014-10-01

    A temperature pause introduced in a simple single-step thermal decomposition of iron, with the presence of silver seeds formed in the same reaction mixture, gives rise to novel compact heterostructures: brick-like Ag@Fe3O4 core-shell nanoparticles. This novel method is relatively easy to implement, and could contribute to overcome the challenge of obtaining a multifunctional heteroparticle in which a noble metal is surrounded by magnetite. Structural analyses of the samples show 4 nm silver nanoparticles wrapped within compact cubic external structures of Fe oxide, with curious rectangular shape. The magnetic properties indicate a near superparamagnetic like behavior with a weak hysteresis at room temperature. The value of the anisotropy involved makes these particles candidates to potential applications in nanomedicine.

  1. Ferrate(VI)-induced arsenite and arsenate removal by in situ structural incorporation into magnetic iron(III) oxide nanoparticles.

    PubMed

    Prucek, Robert; Tuček, Jiří; Kolařík, Jan; Filip, Jan; Marušák, Zdeněk; Sharma, Virender K; Zbořil, Radek

    2013-04-01

    We report the first example of arsenite and arsenate removal from water by incorporation of arsenic into the structure of nanocrystalline iron(III) oxide. Specifically, we show the capability to trap arsenic into the crystal structure of γ-Fe2O3 nanoparticles that are in situ formed during treatment of arsenic-bearing water with ferrate(VI). In water, decomposition of potassium ferrate(VI) yields nanoparticles having core-shell nanoarchitecture with a γ-Fe2O3 core and a γ-FeOOH shell. High-resolution X-ray photoelectron spectroscopy and in-field (57)Fe Mössbauer spectroscopy give unambiguous evidence that a significant portion of arsenic is embedded in the tetrahedral sites of the γ-Fe2O3 spinel structure. Microscopic observations also demonstrate the principal effect of As doping on crystal growth as reflected by considerably reduced average particle size and narrower size distribution of the "in-situ" sample with the embedded arsenic compared to the "ex-situ" sample with arsenic exclusively sorbed on the iron oxide nanoparticle surface. Generally, presented results highlight ferrate(VI) as one of the most promising candidates for advanced technologies of arsenic treatment mainly due to its environmentally friendly character, in situ applicability for treatment of both arsenites and arsenates, and contrary to all known competitive technologies, firmly bound part of arsenic preventing its leaching back to the environment. Moreover, As-containing γ-Fe2O3 nanoparticles are strongly magnetic allowing their separation from the environment by application of an external magnet.

  2. Ferrate(VI)-induced arsenite and arsenate removal by in situ structural incorporation into magnetic iron(III) oxide nanoparticles.

    PubMed

    Prucek, Robert; Tuček, Jiří; Kolařík, Jan; Filip, Jan; Marušák, Zdeněk; Sharma, Virender K; Zbořil, Radek

    2013-04-01

    We report the first example of arsenite and arsenate removal from water by incorporation of arsenic into the structure of nanocrystalline iron(III) oxide. Specifically, we show the capability to trap arsenic into the crystal structure of γ-Fe2O3 nanoparticles that are in situ formed during treatment of arsenic-bearing water with ferrate(VI). In water, decomposition of potassium ferrate(VI) yields nanoparticles having core-shell nanoarchitecture with a γ-Fe2O3 core and a γ-FeOOH shell. High-resolution X-ray photoelectron spectroscopy and in-field (57)Fe Mössbauer spectroscopy give unambiguous evidence that a significant portion of arsenic is embedded in the tetrahedral sites of the γ-Fe2O3 spinel structure. Microscopic observations also demonstrate the principal effect of As doping on crystal growth as reflected by considerably reduced average particle size and narrower size distribution of the "in-situ" sample with the embedded arsenic compared to the "ex-situ" sample with arsenic exclusively sorbed on the iron oxide nanoparticle surface. Generally, presented results highlight ferrate(VI) as one of the most promising candidates for advanced technologies of arsenic treatment mainly due to its environmentally friendly character, in situ applicability for treatment of both arsenites and arsenates, and contrary to all known competitive technologies, firmly bound part of arsenic preventing its leaching back to the environment. Moreover, As-containing γ-Fe2O3 nanoparticles are strongly magnetic allowing their separation from the environment by application of an external magnet. PMID:23451768

  3. Synthesis of phase-pure and monodisperse iron oxide nanoparticles by thermal decomposition.

    PubMed

    Hufschmid, Ryan; Arami, Hamed; Ferguson, R Matthew; Gonzales, Marcela; Teeman, Eric; Brush, Lucien N; Browning, Nigel D; Krishnan, Kannan M

    2015-07-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) are used for a wide range of biomedical applications requiring precise control over their physical and magnetic properties, which are dependent on their size and crystallographic phase. Here we present a comprehensive template for the design and synthesis of iron oxide nanoparticles with control over size, size distribution, phase, and resulting magnetic properties. We investigate critical parameters for synthesis of monodisperse SPIONs by organic thermal decomposition. Three different, commonly used, iron containing precursors (iron oleate, iron pentacarbonyl, and iron oxyhydroxide) are evaluated under a variety of synthetic conditions. We compare the suitability of these three kinetically controlled synthesis protocols, which have in common the use of iron oleate as a starting precursor or reaction intermediate, for producing nanoparticles with specific size and magnetic properties. Monodisperse particles were produced over a tunable range of sizes from approximately 2-30 nm. Reaction parameters such as precursor concentration, addition of surfactant, temperature, ramp rate, and time were adjusted to kinetically control size and size-distribution, phase, and magnetic properties. In particular, large quantities of excess surfactant (up to 25 : 1 molar ratio) alter reaction kinetics and result in larger particles with uniform size; however, there is often a trade-off between large particles and a narrow size distribution. Iron oxide phase, in addition to nanoparticle size and shape, is critical for establishing magnetic properties such as differential susceptibility (dm/dH) and anisotropy. As an example, we show the importance of obtaining the required size and iron oxide phase for application to Magnetic Particle Imaging (MPI), and describe how phase purity can be controlled. These results provide much of the information necessary to determine which iron oxide synthesis protocol is best suited to a particular

  4. Laser-based synthesis of core Ag-shell AgI nanoparticles

    NASA Astrophysics Data System (ADS)

    Tan, Hua; Fan, Wai Yip

    2005-05-01

    A laser-controlled synthesis of silver iodide (AgI) nanoparticles with isolable AgI shell-Ag core stable intermediates is achieved via molecular iodine photodissociation in the presence of pure Ag nanoparticles dispersed in water. Ag nanoparticles were introduced into the solution containing sodium dodecylsulphate surfactants and iodine by ablating a piece of silver foil with a 532 nm pulsed Nd-YAG laser. Transmission electron microscopy images showed that different AgI shell-Ag core sizes could be achieved by controlling the photolysis of I 2 in solution. These nanoparticles were also found to catalyse an atom-economy Grignard-Barbier organic reaction.

  5. Thermally modulated photoacoustic imaging with super-paramagnetic iron oxide nanoparticles.

    PubMed

    Feng, Xiaohua; Gao, Fei; Zheng, Yuanjin

    2014-06-15

    Thermally modulated photoacoustic imaging (TMPI) is reported here for contrast enhancement when using nanoparticles as contrast agents. Exploiting the excellent sensitivity of the photoacoustic (PA) process on temperature and the highly selective heating capability of nanoparticles under electromagnetic field, the PA signals stemming from the nanoparticles labeled region can be efficiently modulated whereas those from highly light absorptive backgrounds are minimally affected. A coherent difference imaging procedure reduces the background signal and thus improves the imaging contrast. Phantom experiments with super-paramagnetic iron oxide nanoparticles (SPIONs) as contrast agents and alternating magnetic fields for heating are demonstrated. Further improvements toward clinical applications are also discussed. PMID:24978499

  6. Preparation of highly dispersed core/shell-type titania nanocapsules containing a single Ag nanoparticle.

    PubMed

    Sakai, Hideki; Kanda, Takashi; Shibata, Hirobumi; Ohkubo, Takahiro; Abe, Masahiko

    2006-04-19

    Core/shell-type titania nanocapsules containing a single Ag nanoparticle were prepared. Ag nanoparticles were prepared using the reduction of silver nitrate with hydrazine in the presence of cetyltrimethylammonium bromide (CTAB) as protective agent. The sol-gel reaction of titanium tetraisopropoxide (TTIP) was used to prepare core/shell-type titania nanocapsules with CTAB-coated Ag nanoparticles as the core. TEM observations revealed that the size of the core (Ag particle) and the thickness of the shell (titania) of the core/shell particles obtained are about 10 nm and 5-10 nm, respectively. In addition, the nanocapsules were found to be dispersed in the medium as individual particles without aggregation. Moreover, titania coating caused the surface plasmon absorption of Ag nanoparticles to shift toward the longer wavelength side. PMID:16608315

  7. Size dependence of inter- and intra-cluster interactions in core-shell iron-iron oxide nanoclusters

    SciTech Connect

    Kaur, Maninder; McCloy, John S.; Jiang, Weilin; Yao, Qi; Qiang, You

    2012-06-15

    The room temperature magnetic properties of core-shell iron-iron oxide nanoclusters (NCs) synthesized by a cluster deposition system have been investigated, and their dependence on mean cluster size has been discussed. In this study, the surface/boundary spins of clusters were not frozen and were thermally activated during the measurements. The inter-cluster interactions between clusters and intra-cluster interactions between the iron core (ferromagnetic) and iron oxide shell (ferrimagnetic) have been investigated by field dependent isothermal remanent magnetization and dc demagnetization measurements at room temperature. The Henkel plot and delta M plot support the existence of dipolar inter-cluster interactions which become stronger with the growth of cluster size. The derivative of the initial magnetization curve implies that smaller clusters require less field and time than the bigger ones to overcome various energy barriers before aligning along the field direction. Coercive field and magnetization are also correlated with the interaction parameters. To compare the room temperature magnetic results, one system was studied at low temperature, where exchange coupling at the interface between the oxide and metallic phases was observed through bias effect and anisotropy enhancement.

  8. Liquid Iron Alloys with Hydrogen at Outer Core Conditions by First Principles

    NASA Astrophysics Data System (ADS)

    Umemoto, K.; Hirose, K.

    2015-12-01

    Since the density of the outer core deduced from seismic data is about 10% lower than that of pure iron at core pressures and temperatures (P-T), it is widely believed that the outer core includes one or more light elements. Although intensive experimental and theoretical studies have been performed so far, the light element in the core has not yet been identified. Comparison of the density and sound velocity of liquid iron alloys with observations, such as the PREM, is a promising way to determine the species and quantity of light alloying component(s) in the outer core. Here we report the results of a first-principles molecular dynamics study on liquid iron alloyed with hydrogen, one of candidates of the light elements. Hydrogen had been much less studied than other candidates. However, hydrogen has been known to reduce the melting temperature of Fe-H solid [1]. Furthermore, very recently, Nomura et al. argued that the outer core may include 24 at.% H in order to be molten under relatively low temperature (< 3600 K) [2]. Since then hydrogen has attracted strong interests. We clarify the effects of hydrogen on density and sound velocity of liquid iron alloys under outer core P-T conditions. It is shown that ~1 wt% hydrogen can reproduce PREM density and sound velocity simultaneously very well. In addition, we show the presence of hydrogen rather reduces Gruneisen parameters. It indicates that, if hydrogen exists in the outer core, temperature profile of the outer core could be changed considerably from one estimated so far. [1] Sakamaki, K., E. Takahashi, Y. Nakajima, Y. Nishihara, K. Funakoshi, T. Suzuki, and Y. Fukai, Phys. Earth Planet. Inter., 174, 192-201 (2009). [2] Nomura, R., K. Hirose, K. Uesugi, Y. Ohishi, A. Tsuchiyama, A. Miyake, and Y. Ueno, Science 31, 522-525 (2014).

  9. Versatile and Biomass Synthesis of Iron-based Nanoparticles Supported on Carbon Matrix with High Iron Content and Tunable Reactivity

    SciTech Connect

    Zhang, Dongmao; Shi, Sheldon Q; Jiang, Dongping; Che, Wen; Gai, Zheng; Howe, Jane Y; More, Karren Leslie; Arockiasamy, Antonyraj

    2012-01-01

    Iron-based nanoparticles supported on carbon (FeNPs{at}C) have enormous potential for environmental applications. Reported is a biomass-based method for FeNP{at}C synthesis that involves pyrolysis of bleached wood fiber pre-mixed with Fe{sub 3}O{sub 4} nanoparticles. This method allows synthesis of iron-based nanoparticles with tunable chemical reactivity by changing the pyrolysis temperature. The FeNP{at}C synthesized at a pyrolysis temperature of 500 C (FeNP{at}C-500) reacts violently (pyrophoric) when exposed to air, while FeNP{at}C prepared at 800 C (FeNP{at}C-800) remains stable in ambient condition for at least 3 months. The FeNPs in FeNP{at}C-800 are mostly below 50 nm in diameter and are surrounded by carbon. The immediate carbon layer (within 5-15 nm radius) on the FeNPs is graphitized. Proof-of-concept environmental applications of FeNPs{at}C-800 were demonstrated by Rhodamine 6G and arsenate (V) removal from water. This biomass-based method provides an effective way for iron-based nanoparticle fabrication and biomass utilization.

  10. Glioma-targeted superparamagnetic iron oxide nanoparticles as drug-carrying vehicles for theranostic effects.

    PubMed

    Xu, He-Lin; Mao, Kai-Li; Huang, Yin-Ping; Yang, Jing-Jing; Xu, Jie; Chen, Pian-Pian; Fan, Zi-Liang; Zou, Shuang; Gao, Zheng-Zheng; Yin, Jia-Yu; Xiao, Jian; Lu, Cui-Tao; Zhang, Bao-Lin; Zhao, Ying-Zheng

    2016-08-01

    Multifunctional nanoparticles capable of the specific delivery of therapeutics to diseased cells and the real-time imaging of these sites have the potential to improve cancer treatment through personalized therapy. In this study, we have proposed a multifunctional nanoparticle that integrate magnetic targeting, drug-carrier functionality and real-time MRI imaging capabilities in one platform for the theranostic treatment of tumors. The multifunctional nanoparticle was designed with a superparamagnetic iron oxide core and a multifunctional shell composed of PEG/PEI/polysorbate 80 (Ps 80) and was used to encapsulate DOX. DOX-loaded multifunctional nanoparticles (DOX@Ps 80-SPIONs) with a Dh of 58.0 nm, a zeta potential of 28.0 mV, and a drug loading content of 29.3% presented superior superparamagnetic properties with a saturation magnetization (Ms) of 24.1 emu g(-1). The cellular uptake of DOX@Ps 80-SPIONs by C6 cells under a magnetic field was significantly enhanced over that of free DOX in solution, resulting in stronger in vitro cytotoxicity. The real-time therapeutic outcome of DOX@Ps 80-SPIONs was easily monitored by MRI. Furthermore, the negative contrast enhancement effect of the nanoparticles was confirmed in glioma-bearing rats. Prussian blue staining and ex vivo DOX fluorescence assays showed that the magnetic Ps 80-SPIONs and encapsulated DOX were delivered to gliomas by imposing external magnetic fields, indicating effective magnetic targeting. Due to magnetic targeting and Ps 80-mediated endocytosis, DOX@Ps 80-SPIONs in the presence of a magnetic field led to the complete suppression of glioma growth in vivo at 28 days after treatment. The therapeutic mechanism of DOX@Ps 80-SPIONs acted by inducing apoptosis through the caspase-3 pathway. Finally, DOX@Ps 80-SPIONs' safety at therapeutic dosage was verified using pathological HE assays of the heart, liver, spleen, lung and kidney. Multifunctional SPIONs could be used as potential carriers for the

  11. Massive Intracellular Biodegradation of Iron Oxide Nanoparticles Evidenced Magnetically at Single-Endosome and Tissue Levels.

    PubMed

    Mazuel, François; Espinosa, Ana; Luciani, Nathalie; Reffay, Myriam; Le Borgne, Rémi; Motte, Laurence; Desboeufs, Karine; Michel, Aude; Pellegrino, Teresa; Lalatonne, Yoann; Wilhelm, Claire

    2016-08-23

    Quantitative studies of the long-term fate of iron oxide nanoparticles inside cells, a prerequisite for regenerative medicine applications, are hampered by the lack of suitable biological tissue models and analytical methods. Here, we propose stem-cell spheroids as a tissue model to track intracellular magnetic nanoparticle transformations during long-term tissue maturation. We show that global spheroid magnetism can serve as a fingerprint of the degradation process, and we evidence a near-complete nanoparticle degradation over a month of tissue maturation, as confirmed by electron microscopy. Remarkably, the same massive degradation was measured at the endosome level by single-endosome nanomagnetophoretic tracking in cell-free endosomal extract. Interestingly, this spectacular nanoparticle breakdown barely affected iron homeostasis: only the genes coding for ferritin light chain (iron loading) and ferroportin (iron export) were up-regulated 2-fold by the degradation process. Besides, the magnetic and tissular tools developed here allow screening of the biostability of magnetic nanomaterials, as demonstrated with iron oxide nanocubes and nanodimers. Hence, stem-cell spheroids and purified endosomes are suitable models needed to monitor nanoparticle degradation in conjunction with magnetic, chemical, and biological characterizations at the cellular scale, quantitatively, in the long term, in situ, and in real time. PMID:27419260

  12. Vapour phase approach for iron oxide nanoparticle synthesis from solid precursors

    SciTech Connect

    Singh, Mandeep; Ulbrich, Pavel; Prokopec, Vadym; Svoboda, Pavel; Šantavá, Eva; Štěpánek, František

    2013-04-15

    A new non-solution mediated approach to the synthesis of iron oxide nanoparticles directly from solid FeCl{sub 2} salt precursors has been developed. The method is rapid, simple and scalable. The structural properties and the phase of the resulting iron oxide particles has been determined by a range of methods including XRD, FT-IR and Mössbauer spectroscopy, and the phase is shown to be maghemite (γ-Fe{sub 2}O{sub 3}). The magnetic properties of the iron oxide particles have been measured using SQUID, confirming superparamagnetic behaviour of the powder and a saturation magnetization of 53.0 emu g{sup −1} at 300 K. Aqueous dispersions at increasing concentrations were prepared and their heating rate under a 400 kHz alternating magnetic field measured. The specific absorption rate (SAR) of the iron oxide was found to be 84.8 W g{sup −1}, which makes the material suitable for the formulation of ferrofluids or ferrogels with RF heating properties. - Graphical Abstract: Superparamagnetic iron oxide nanoparticles obtained by a novel vapour phase approach. Highlights: ► Novel vapour phase (non-solvent) approach for iron oxide nanoparticle synthesis. ► Attractive alternative approach to the present co-precipitation method. ► Better magnetic properties with high coercivity of nanoparticles. ► A high specific absorption rate (SAR) for hyperthermia applications.

  13. Nanobiocomposite from Collagen Waste Using Iron Oxide Nanoparticles and Its Conversion Into Magnetic Nanocarbon.

    PubMed

    Thanikaivelan, P; Narayanan, T N; Gupta, B K; Reddy, A L M; Ajayan, P M

    2015-06-01

    Collagenous wastes discarded from leather industry were stabilized using superparamagnetic iron oxide nanoparticles and further converted into a magnetic nanocarbon. Stabilization of collagen using iron oxide nanoparticles treatment (25% offer) was confirmed through differential scanning calorimetric analysis and further evidenced through scanning electron microscopic analysis. A simple high temperature treatment of the collagen-iron oxide nanoparticle composite at 850 degrees C for 2 h under Ar atmosphere yielded a bi-functional, magnetic and conducting, nanocarbon. The X-ray diffraction and Raman spectroscopic analysis reveal the partial graphitation and X-ray photoelectron spectroscopic results show the presence of trace-iron containing carbon, naturally doped with nitrogen and oxygen. Transmission electron microscopic analysis show the presence of larger iron oxide nanocrystals embedded in graphitic carbon layers while superconducting quantum interference device based analysis reveals a perfect ferrimagnetic property with saturation magnetization. Thus, we have stabilized the collagen waste fibers using iron oxide nanoparticles and converted them into a bi-functional nanocarbon, which has potential for various applications including energy, leather making and environmental remediation. PMID:26369072

  14. Antimicrobial activity of iron oxide nanoparticle upon modulation of nanoparticle-bacteria interface

    NASA Astrophysics Data System (ADS)

    Arakha, Manoranjan; Pal, Sweta; Samantarrai, Devyani; Panigrahi, Tapan K.; Mallick, Bairagi C.; Pramanik, Krishna; Mallick, Bibekanand; Jha, Suman

    2015-10-01

    Investigating the interaction patterns at nano-bio interface is a key challenge for safe use of nanoparticles (NPs) to any biological system. The study intends to explore the role of interaction pattern at the iron oxide nanoparticle (IONP)-bacteria interface affecting antimicrobial propensity of IONP. To this end, IONP with magnetite like atomic arrangement and negative surface potential (n-IONP) was synthesized by co-precipitation method. Positively charged chitosan molecule coating was used to reverse the surface potential of n-IONP, i.e. positive surface potential IONP (p-IONP). The comparative data from fourier transform infrared spectroscope, XRD, and zeta potential analyzer indicated the successful coating of IONP surface with chitosan molecule. Additionally, the nanocrystals obtained were found to have spherical size with 10-20 nm diameter. The BacLight fluorescence assay, bacterial growth kinetic and colony forming unit studies indicated that n-IONP (<50 μM) has insignificant antimicrobial activity against Bacillus subtilis and Escherichia coli. However, coating with chitosan molecule resulted significant increase in antimicrobial propensity of IONP. Additionally, the assay to study reactive oxygen species (ROS) indicated relatively higher ROS production upon p-IONP treatment of the bacteria. The data, altogether, indicated that the chitosan coating of IONP result in interface that enhances ROS production, hence the antimicrobial activity.

  15. Antimicrobial activity of iron oxide nanoparticle upon modulation of nanoparticle-bacteria interface

    PubMed Central

    Arakha, Manoranjan; Pal, Sweta; Samantarrai, Devyani; Panigrahi, Tapan K.; Mallick, Bairagi C.; Pramanik, Krishna; Mallick, Bibekanand; Jha, Suman

    2015-01-01

    Investigating the interaction patterns at nano-bio interface is a key challenge for safe use of nanoparticles (NPs) to any biological system. The study intends to explore the role of interaction pattern at the iron oxide nanoparticle (IONP)-bacteria interface affecting antimicrobial propensity of IONP. To this end, IONP with magnetite like atomic arrangement and negative surface potential (n-IONP) was synthesized by co-precipitation method. Positively charged chitosan molecule coating was used to reverse the surface potential of n-IONP, i.e. positive surface potential IONP (p-IONP). The comparative data from fourier transform infrared spectroscope, XRD, and zeta potential analyzer indicated the successful coating of IONP surface with chitosan molecule. Additionally, the nanocrystals obtained were found to have spherical size with 10–20 nm diameter. The BacLight fluorescence assay, bacterial growth kinetic and colony forming unit studies indicated that n-IONP (<50 μM) has insignificant antimicrobial activity against Bacillus subtilis and Escherichia coli. However, coating with chitosan molecule resulted significant increase in antimicrobial propensity of IONP. Additionally, the assay to study reactive oxygen species (ROS) indicated relatively higher ROS production upon p-IONP treatment of the bacteria. The data, altogether, indicated that the chitosan coating of IONP result in interface that enhances ROS production, hence the antimicrobial activity. PMID:26437582

  16. Influence of carbon chain length on the synthesis and yield of fatty amine-coated iron-platinum nanoparticles

    PubMed Central

    2014-01-01

    Iron oxide nanoparticles are among the most widely used and characterized magnetic nanoparticles. However, metal alloys such as superparamagnetic iron-platinum particles (SIPPs), which have better magnetic properties, are receiving increased attention. Scalable techniques to routinely synthesize SIPPs in bulk need further study. Here, we focus on the role played by the fatty amine ligand in the formation of the bimetallic FePt nanocrystal. More specifically, we compare the effect of varying lengths of fatty amine ligands on the shape, structure, uniformity, composition, and magnetic properties of the SIPPs. We synthesized SIPPs by employing a ‘green’ thermal decomposition reaction using fatty amine ligands containing 12 to 18 carbons in length. Greater fatty amine chain length increased the polydispersity, particle concentration, iron concentration, and the stability of the SIPPs. Additionally, longer reflux times increased the diameter of the particles, but decreased the iron concentration, suggesting that shorter reaction times are preferable. Fourier transform infrared spectroscopy of the SIPPs indicates that the ligands are successfully bound to the FePt cores through the amine group. Superconducting quantum interference device magnetometry measurements suggest that all of the SIPPs were superparamagnetic at room temperature and that SIPPs synthesized using tetradecylamine had the highest saturation magnetization. Our findings indicate that the octadecylamine ligand, which is currently used for the routine synthesis of SIPPs, may not be optimal. Overall, we found that using tetradecylamine and a 30-min reflux reaction resulted in optimal particles with the highest degree of monodispersity, iron content, stability, and saturation magnetization. PACS 81.07.-b; 75.75.Fk; 61.46.Df PMID:25006334

  17. One-pot synthesis of magnetic graphene nanocomposites decorated with core@double-shell nanoparticles for fast chromium removal.

    PubMed

    Zhu, Jiahua; Wei, Suying; Gu, Hongbo; Rapole, Sowjanya B; Wang, Qiang; Luo, Zhiping; Haldolaarachchige, Neel; Young, David P; Guo, Zhanhu

    2012-01-17

    A facile thermodecomposition process to synthesize magnetic graphene nanocomposites (MGNCs) is reported. High-resolution transmission electron microscopy and energy filtered elemental mapping revealed a core@double-shell structure of the nanoparticles with crystalline iron as the core, iron oxide as the inner shell and amorphous Si-S-O compound as the outer shell. The MGNCs demonstrate an extremely fast Cr(VI) removal from the wastewater with a high removal efficiency and with an almost complete removal of Cr(VI) within 5 min. The adsorption kinetics follows the pseudo-second-order model and the novel MGNC adsorbent exhibits better Cr(VI) removal efficiency in solutions with low pH. The large saturation magnetization (96.3 emu/g) of the synthesized nanoparticles allows fast separation of the MGNCs from liquid suspension. By using a permanent magnet, the recycling process of both the MGNC adsorbents and the adsorbed Cr(VI) is more energetically and economically sustainable. The significantly reduced treatment time required to remove the Cr(VI) and the applicability in treating the solutions with low pH make MGNCs promising for the efficient removal of heavy metals from the wastewater. PMID:22126606

  18. Bacitracin-conjugated superparamagnetic iron oxide nanoparticles: synthesis, characterization and antibacterial activity.

    PubMed

    Zhang, Wenjing; Shi, Xinhao; Huang, Jing; Zhang, Yixuan; Wu, Zirong; Xian, Yuezhong

    2012-10-01

    Bacitracin-conjugated superparamagnetic iron oxide (Fe(3)O(4)) nanoparticles were prepared by click chemistry and their antibacterial activity was investigated. After functionalization with hydrophilic and biocompatible poly(acrylic acid), water-soluble Fe(3)O(4) nanoparticles were obtained. Propargylated Fe(3)O(4) nanoparticles were then synthesized by carbodiimide reaction of propargylamine with the carboxyl groups on the surface of the iron oxide nanoparticles. By further reaction with N(3)-bacitracin in a Cu(I)-catalyzed azide-alkyne cycloaddition, the magnetic Fe(3)O(4) nanoparticles were modified with the peptide bacitracin. The functionalized magnetic nanoparticles were characterized by powder X-ray diffraction, X-ray photoelectron spectroscopy, TEM, zeta-potential analysis, FTIR spectroscopy and vibrating-sample magnetometry. Cell cytotoxicity tests indicate that bacitracin-conjugated Fe(3)O(4) nanoparticles show very low cytotoxicity to human fibroblast cells, even at relatively high concentrations. In view of the antibacterial activity of bacitracin, the biofunctionalized Fe(3)O(4) nanoparticles exhibit an antibacterial effect against both Gram-positive and Gram-negative organisms, which is even higher than that of bacitracin itself. The enhanced antibacterial activity of the magnetic nanocomposites allows the dosage and the side effects of the antibiotic to be reduced. Due to the antibacterial effect and magnetism, the bacitracin-functionalized magnetic nanoparticles have potential application in magnetic-targeting biomedical applications.

  19. Evaluation of folate conjugated superparamagnetic iron oxide nanoparticles for scintigraphic/magnetic resonance imaging.

    PubMed

    Chauhan, Ram Prakash; Mathur, Rashi; Singh, Gurjaspreet; Kaul, Ankur; Bag, Narmada; Singh, Sweta; Kumar, Hemanth; Patra, Manoj; Mishra, Anil K

    2013-03-01

    The physical and chemical properties of the nanoparticles influence their pharmacokinetics and ability to accumulate in tumors. In this paper we report a facile method to conjugate folic acid molecule to iron oxide nanoparticles to increase the specific uptake of these nanoparticles by the tumor, which will be useful in targeted imaging of the tumor. The iron oxide nanoparticles were synthesized by alkaline co precipitation method and were surface modified with dextranto make them stable. The folic acid is conjugated to the dextran modified iron oxide nanoparticles by reductive amination process after the oxidation of the dextran with periodate. The synthesized folic acid conjugated nanoparticles were characterized for size, phase, morphology and magnetization by using various physicochemical characterization techniques such as transmission electron microscopy, X-ray diffraction, fourier transform infrared spectroscopy, vibrating sample magnetometry, dynamic light scattering and zetasizer etc. The quantification of the generated carbonyl groups and folic acid conjugated to the surface of the magnetic nanoparticles was done by colorimetric estimations using UV-Visible spectroscopy. The in vitro MR studies were carried out over a range of concentrations and showed significant shortening of the transverse relaxation rate, showing the ability of the nanoconjugate to act as an efficient probe for MR imaging. The biodistribution studies and the scintigraphy done by radiolabeling the nanoconjugate with 99mTc show the enhanced uptake at the tumor site showing its enhanced specificity. PMID:23620987

  20. Sonochemical Synthesis and Magnetic Imaging of Hollow-Shell Iron-Platinum Nanoparticles

    NASA Astrophysics Data System (ADS)

    Baker, Remmi; Barnes, Paris; Martell, Eric

    2015-04-01

    As science has continued to evolve, scientists have been diving deeper and deeper, researching and analyzing the tiniest of objects. Interestingly, materials such as gold, silver, iron, and platinum behave differently on the nanoscale than the macroscale. Discrepancies between the behaviors of macro- and nanoparticles of the same substance are not well understood, which has led scientists to pursue the question as to why nanoparticles behave differently. Further research into the fabrication of hollow-shell iron-platinum nanoparticles and their unique properties may lead to real-world applications. Iron-platinum (FePt) nanoparticles are recognized for their unique magnetic properties; however, these properties have largely not been researched. FePt samples were prepared using sonochemical techniques. We report on the magnetic force microscopy imaging for self-assembled hollow-shell FePt nanoparticles, and relate our findings to the physical characteristics of the hollow-shell FePt nanoparticles. Additionally, we investigate the magnetic properties for FePt nanoparticles by analyzing the role of the electrons and their interactions occurring within the magnetic domain.

  1. Evaluation of folate conjugated superparamagnetic iron oxide nanoparticles for scintigraphic/magnetic resonance imaging.

    PubMed

    Chauhan, Ram Prakash; Mathur, Rashi; Singh, Gurjaspreet; Kaul, Ankur; Bag, Narmada; Singh, Sweta; Kumar, Hemanth; Patra, Manoj; Mishra, Anil K

    2013-03-01

    The physical and chemical properties of the nanoparticles influence their pharmacokinetics and ability to accumulate in tumors. In this paper we report a facile method to conjugate folic acid molecule to iron oxide nanoparticles to increase the specific uptake of these nanoparticles by the tumor, which will be useful in targeted imaging of the tumor. The iron oxide nanoparticles were synthesized by alkaline co precipitation method and were surface modified with dextranto make them stable. The folic acid is conjugated to the dextran modified iron oxide nanoparticles by reductive amination process after the oxidation of the dextran with periodate. The synthesized folic acid conjugated nanoparticles were characterized for size, phase, morphology and magnetization by using various physicochemical characterization techniques such as transmission electron microscopy, X-ray diffraction, fourier transform infrared spectroscopy, vibrating sample magnetometry, dynamic light scattering and zetasizer etc. The quantification of the generated carbonyl groups and folic acid conjugated to the surface of the magnetic nanoparticles was done by colorimetric estimations using UV-Visible spectroscopy. The in vitro MR studies were carried out over a range of concentrations and showed significant shortening of the transverse relaxation rate, showing the ability of the nanoconjugate to act as an efficient probe for MR imaging. The biodistribution studies and the scintigraphy done by radiolabeling the nanoconjugate with 99mTc show the enhanced uptake at the tumor site showing its enhanced specificity.

  2. Endothelial dysfunction and inflammation induced by iron oxide nanoparticle exposure: Risk factors for early atherosclerosis.

    PubMed

    Zhu, Mo-Tao; Wang, Bing; Wang, Yun; Yuan, Lan; Wang, Hua-Jian; Wang, Meng; Ouyang, Hong; Chai, Zhi-Fang; Feng, Wei-Yue; Zhao, Yu-Liang

    2011-06-10

    More recently, the correlation between exposure to nanoparticles and cardiovascular diseases is of particular concern in nanotoxicology related fields. Nanoparticle-triggered endothelial dysfunction is hypothesized to be a dominant mechanism in the development of the diseases. To test this hypothesis, iron oxide nanoparticles (Fe₂O₃ and Fe₃O₄), as two widely used nanomaterials and the main metallic components in particulate matter, were selected to assess their potential risks on human endothelial system. The direct effects of iron oxide nanoparticles on human aortic endothelial cells (HAECs) and the possible effects mediated by monocyte (U937 cells) phagocytosis and activation were investigated. In the study, HAECs and U937 cells were exposed to 2, 20, 100 μg/mL of 22-nm-Fe₂O₃ and 43-nm-Fe₃O₄ particles. Our results indicate that cytoplasmic vacuolation, mitochondrial swelling and cell death were induced in HAEC. A significant increase in nitric oxide (NO) production was induced which coincided with the elevation of nitric oxide synthase (NOS) activity in HAECs. Adhesion of monocytes to the HAECs was significantly enhanced as a consequence of the up-regulation of intracellular cell adhesion molecule-1 (ICAM-1) and interleukin-8 (IL-8) expression, all of which are considered as early steps of atheroscelerosis. Phagocytosis and dissolution of nanoparticles by monocytes were found to simultaneously provoke oxidative stress and mediate severe endothelial toxicity. We conclude that intravascular iron oxide nanoparticles may induce endothelial system inflammation and dysfunction by three ways: (1) nanoparticles may escape from phagocytosis that interact directly with the endothelial monolayer; (2) nanoparticles are phagocytized by monocytes and then dissolved, thus impact the endothelial cells as free iron ions; or (3) nanoparticles are phagocytized by monocytes to provoke oxidative stress responses.

  3. Transmission electron microscopy and ab initio calculations to relate interfacial intermixing and the magnetism of core/shell nanoparticles

    SciTech Connect

    Chi, C.-C.; Hsiao, C.-H.; Ouyang, Chuenhou; Skoropata, E.; Lierop, J. van

    2015-05-07

    Significant efforts towards understanding bi-magnetic core-shell nanoparticles are underway currently as they provide a pathway towards properties unavailable with single-phased systems. Recently, we have demonstrated that the magnetism of γ-Fe2O3/CoO core-shell nanoparticles, in particular, at high temperatures, originates essentially from an interfacial doped iron-oxide layer that is formed by the migration of Co{sup 2+} from the CoO shell into the surface layers of the γ-Fe2O3 core [Skoropata et al., Phys. Rev. B 89, 024410 (2014)]. To examine directly the nature of the intermixed layer, we have used high-resolution transmission electron microscopy (HRTEM) and first-principles calculations to examine the impact of the core-shell intermixing at the atomic level. By analyzing the HRTEM images and energy dispersive spectra, the level and nature of intermixing was confirmed, mainly as doping of Co into the octahedral site vacancies of γ-Fe2O3. The average Co doping depths for different processing temperatures (150 °C and 235 °C) were 0.56 nm and 0.78 nm (determined to within 5% through simulation), respectively, establishing that the amount of core-shell intermixing can be altered purposefully with an appropriate change in synthesis conditions. Through first-principles calculations, we find that the intermixing phase of γ-Fe2O3 with Co doping is ferromagnetic, with even higher magnetization as compared to that of pure γ-Fe2O3. In addition, we show that Co doping into different octahedral sites can cause different magnetizations. This was reflected in a change in overall nanoparticle magnetization, where we observed a 25% reduction in magnetization for the 235 °C versus the 150 °C sample, despite a thicker intermixed layer.

  4. Polystyrene-Core-Silica-Shell Hybrid Particles Containing Gold and Magnetic Nanoparticles.

    PubMed

    Tian, Jia; Vana, Philipp

    2016-02-18

    Polystyrene-core-silica-shell hybrid particles were synthesized by combining the self-assembly of nanoparticles and the polymer with a silica coating strategy. The core-shell hybrid particles are composed of gold-nanoparticle-decorated polystyrene (PS-AuNP) colloids as the core and silica particles as the shell. PS-AuNP colloids were generated by the self-assembly of the PS-grafted AuNPs. The silica coating improved the thermal stability and dispersibility of the AuNPs. By removing the "free" PS of the core, hollow particles with a hydrophobic cage having a AuNP corona and an inert silica shell were obtained. Also, Fe3O4 nanoparticles were encapsulated in the core, which resulted in magnetic core-shell hybrid particles by the same strategy. These particles have potential applications in biomolecular separation and high-temperature catalysis and as nanoreactors.

  5. New surface radiolabeling schemes of super paramagnetic iron oxide nanoparticles (SPIONs) for biodistribution studies.

    PubMed

    Nallathamby, Prakash D; Mortensen, Ninell P; Palko, Heather A; Malfatti, Mike; Smith, Catherine; Sonnett, James; Doktycz, Mitchel J; Gu, Baohua; Roeder, Ryan K; Wang, Wei; Retterer, Scott T

    2015-04-21

    Nanomaterial based drug delivery systems allow for the independent tuning of the surface chemical and physical properties that affect their biodistribution in vivo and the therapeutic payloads that they are intended to deliver. Additionally, the added therapeutic and diagnostic value of their inherent material properties often provides extra functionality. Iron based nanomaterials with their magnetic properties and easily tailorable surface chemistry are of particular interest as model systems. In this study the core radius of the iron oxide nanoparticles (NPs) was 14.08 ± 3.92 nm while the hydrodynamic radius of the NPs, as determined by Dynamic Light Scattering (DLS), was between 90-110 nm. In this study, different approaches were explored to create radiolabeled NPs that are stable in solution. The NPs were functionalized with polycarboxylate or polyamine surface functional groups. Polycarboxylate functionalized NPs had a zeta potential of -35 mV and polyamine functionalized NPs had a zeta potential of +40 mV. The polycarboxylate functionalized NPs were chosen for in vivo biodistribution studies and hence were radiolabeled with (14)C, with a final activity of 0.097 nCi mg(-1) of NPs. In chronic studies, the biodistribution profile is tracked using low level radiolabeled proxies of the nanoparticles of interest. Conventionally, these radiolabeled proxies are chemically similar but not chemically identical to the non-radiolabeled NPs of interest. This study is novel as different approaches were explored to create radiolabeled NPs that are stable, possess a hydrodynamic radius of <100 nm and most importantly they exhibit an identical surface chemical functionality as their non-radiolabeled counterparts. Identical chemical functionality of the radiolabeled probes to the non-radiolabeled probes was an important consideration to generate statistically similar biodistribution data sets using multiple imaging and detection techniques. The radiolabeling approach

  6. New Surface Radiolabeling Schemes of Super Paramagnetic Iron Oxide Nanoparticles (SPIONs) for Biodistribution Studies

    DOE PAGESBeta

    Nallathamby, Prakash D.; Mortensen, Ninell P.; Palko, Heather A.; Malfatti, Mike; Smith, Catherine; Sonnett, Jim; Doktycz, Mitchel John; Gu, Baohua; Roeder, Ryan; Wang, Wei; et al

    2015-01-01

    Nanomaterial based drug delivery systems allow for the independent tuning of the surface chemical and physical properties that affect their biodistribution in vivo and the therapeutic payloads that they are intended to deliver. Additionally, the added therapeutic and diagnostic value of their inherent material properties often provides extra functionality. Iron based nanomaterials with their magnetic properties and 10 easily tailorable surface chemistry are of particular interest as model systems. In this study the core radius of the iron oxide nanoparticles (NPs) was 14.08 3.92 nm while the hydrodynamic radius of the NPs, as determined by Dynamic Light Scattering (DLS), wasmore » between 90 110 nm. In this study, different approaches were explored to create radiolabeled NPs that are stable in solution. The NPs were functionalized with polycarboxylate or polyamine surface functional groups. Polycarboxylate 15 functionalized NPs had a zeta potential of -35 mV and polyamine functionalized NPs had a zeta potential of +40 mV. The polycarboxylate functionalized NPs were chosen for in vivo biodistribution studies and hence were radiolabeled with 14C, with a final activity of 0.097 nCi/mg-1 of NPs. In chronic studies, the biodistribution profile is tracked using low level radiolabeled proxies of the nanoparticles of interest. Conventionally, these radiolabeled proxies are chemically similar but not chemically identical to the non-20 radiolabeled NPs of interest. This study is novel as different approaches were explored to create radiolabeled NPs that are stable, possess a hydrodynamic radius of <100 nm and most importantly they exhibit an identical surface chemical functionality as their non-radiolabeled counterparts. Identical chemical functionality of the radiolabeled probes to the non-radiolabeled probes was an important consideration to generate statistically similar biodistribution data sets using multiple imaging and 25 detection techniques. The radiolabeling

  7. New Surface Radiolabeling Schemes of Super Paramagnetic Iron Oxide Nanoparticles (SPIONs) for Biodistribution Studies

    SciTech Connect

    Nallathamby, Prakash D.; Mortensen, Ninell P.; Palko, Heather A.; Malfatti, Mike; Smith, Catherine; Sonnett, Jim; Doktycz, Mitchel John; Gu, Baohua; Roeder, Ryan; Wang, Wei; Retterer, Scott T.

    2015-01-01

    Nanomaterial based drug delivery systems allow for the independent tuning of the surface chemical and physical properties that affect their biodistribution in vivo and the therapeutic payloads that they are intended to deliver. Additionally, the added therapeutic and diagnostic value of their inherent material properties often provides extra functionality. Iron based nanomaterials with their magnetic properties and 10 easily tailorable surface chemistry are of particular interest as model systems. In this study the core radius of the iron oxide nanoparticles (NPs) was 14.08 3.92 nm while the hydrodynamic radius of the NPs, as determined by Dynamic Light Scattering (DLS), was between 90 110 nm. In this study, different approaches were explored to create radiolabeled NPs that are stable in solution. The NPs were functionalized with polycarboxylate or polyamine surface functional groups. Polycarboxylate 15 functionalized NPs had a zeta potential of -35 mV and polyamine functionalized NPs had a zeta potential of +40 mV. The polycarboxylate functionalized NPs were chosen for in vivo biodistribution studies and hence were radiolabeled with 14C, with a final activity of 0.097 nCi/mg-1 of NPs. In chronic studies, the biodistribution profile is tracked using low level radiolabeled proxies of the nanoparticles of interest. Conventionally, these radiolabeled proxies are chemically similar but not chemically identical to the non-20 radiolabeled NPs of interest. This study is novel as different approaches were explored to create radiolabeled NPs that are stable, possess a hydrodynamic radius of <100 nm and most importantly they exhibit an identical surface chemical functionality as their non-radiolabeled counterparts. Identical chemical functionality of the radiolabeled probes to the non-radiolabeled probes was an important consideration to generate statistically similar biodistribution data sets using multiple imaging and 25 detection techniques. The

  8. New surface radiolabeling schemes of super paramagnetic iron oxide nanoparticles (SPIONs) for biodistribution studies†

    PubMed Central

    Nallathamby, Prakash D.; Mortensen, Ninell P.; Palko, Heather A.; Malfatti, Mike; Smith, Catherine; Sonnett, James; Doktycz, Mitchel J.; Gu, Baohua; Roeder, Ryan K.; Wang, Wei; Retterer, Scott T.

    2016-01-01

    Nanomaterial based drug delivery systems allow for the independent tuning of the surface chemical and physical properties that affect their biodistribution in vivo and the therapeutic payloads that they are intended to deliver. Additionally, the added therapeutic and diagnostic value of their inherent material properties often provides extra functionality. Iron based nanomaterials with their magnetic properties and easily tailorable surface chemistry are of particular interest as model systems. In this study the core radius of the iron oxide nanoparticles (NPs) was 14.08 ± 3.92 nm while the hydrodynamic radius of the NPs, as determined by Dynamic Light Scattering (DLS), was between 90–110 nm. In this study, different approaches were explored to create radiolabeled NPs that are stable in solution. The NPs were functionalized with polycarboxylate or polyamine surface functional groups. Polycarboxylate functionalized NPs had a zeta potential of –35 mV and polyamine functionalized NPs had a zeta potential of +40 mV. The polycarboxylate functionalized NPs were chosen for in vivo biodistribution studies and hence were radiolabeled with 14C, with a final activity of 0.097 nCi mg–1 of NPs. In chronic studies, the biodistribution profile is tracked using low-level radiolabeled proxies of the nanoparticles of interest. Conventionally, these radiolabeled proxies are chemically similar but not chemically identical to the non-radiolabeled NPs of interest. This study is novel as different approaches were explored to create radiolabeled NPs that are stable, possess a hydrodynamic radius of <100 nm and most importantly they exhibit an identical surface chemical functionality as their non-radiolabeled counterparts. Identical chemical functionality of the radiolabeled probes to the non-radiolabeled probes was an important consideration to generate statistically similar biodistribution data sets using multiple imaging and detection techniques. The radiolabeling approach

  9. High-performance iron oxide nanoparticles for magnetic particle imaging - guided hyperthermia (hMPI)

    NASA Astrophysics Data System (ADS)

    Bauer, Lisa M.; Situ, Shu F.; Griswold, Mark A.; Samia, Anna Cristina S.

    2016-06-01

    Magnetic particle imaging (MPI) is an emerging imaging modality that allows the direct and quantitative mapping of iron oxide nanoparticles. In MPI, the development of tailored iron oxide nanoparticle tracers is paramount to achieving high sensitivity and good spatial resolution. To date, most MPI tracers being developed for potential clinical applications are based on spherical undoped magnetite nanoparticles. For the first time, we report on the systematic investigation of the effects of changes in chemical composition and shape anisotropy on the MPI performance of iron oxide nanoparticle tracers. We observed a 2-fold enhancement in MPI signal through selective doping of magnetite nanoparticles with zinc. Moreover, we demonstrated focused magnetic hyperthermia heating by adapting the field gradient used in MPI. By saturating the iron oxide nanoparticles outside of a field free region (FFR) with an external static field, we can selectively heat a target region in our test sample. By comparing zinc-doped magnetite cubic nanoparticles with undoped spherical nanoparticles, we could show a 5-fold improvement in the specific absorption rate (SAR) in magnetic hyperthermia while providing good MPI signal, thereby demonstrating the potential for high-performance focused hyperthermia therapy through an MPI-guided approach (hMPI).Magnetic particle imaging (MPI) is an emerging imaging modality that allows the direct and quantitative mapping of iron oxide nanoparticles. In MPI, the development of tailored iron oxide nanoparticle tracers is paramount to achieving high sensitivity and good spatial resolution. To date, most MPI tracers being developed for potential clinical applications are based on spherical undoped magnetite nanoparticles. For the first time, we report on the systematic investigation of the effects of changes in chemical composition and shape anisotropy on the MPI performance of iron oxide nanoparticle tracers. We observed a 2-fold enhancement in MPI signal

  10. Magnetite and magnetite/silver core/shell nanoparticles with diluted magnet-like behavior

    SciTech Connect

    Garza-Navarro, Marco; Gonzalez, Virgilio; Ortiz, Ubaldo; De la Rosa, Elder

    2010-01-15

    In the present work is reported the use of the biopolymer chitosan as template for the preparation of magnetite and magnetite/silver core/shell nanoparticles systems, following a two step procedure of magnetite nanoparticles in situ precipitation and subsequent silver ions reduction. The crystalline and morphological characteristics of both magnetite and magnetite/silver core/shell nanoparticles systems were analyzed by high resolution transmission electron microscopy (HRTEM) and nanobeam diffraction patterns (NBD). The results of these studies corroborate the core/shell morphology and the crystalline structure of the magnetite core and the silver shell. Moreover, magnetization temperature dependent, M(T), measurements show an unusual diluted magnetic behavior attributed to the dilution of the magnetic ordering in the magnetite and magnetite/silver core/shell nanoparticles systems. - Graphical abstract: Biopolymer chitosan was used as stabilization media to synthesize both magnetite and magnetite/silver core/shell nanoparticles. Results of HRTEM and NBD patterns confirm core/shell morphology of the obtained nanoparticles. It was found that the composites show diluted magnet-like behavior.

  11. Growth of textured thin Au coatings on iron oxide nanoparticles with near infrared absorbance

    PubMed Central

    Ma, L L; Borwankar, A U; Willsey, B W; Yoon, K Y; Tam, J O; Sokolov, K V; Feldman, M D; Milner, T E; Johnston, K P

    2013-01-01

    A homologous series of Au-coated iron oxide nanoparticles, with hydrodynamic diameters smaller than 60 nm was synthesized with very low Auto-iron mass ratios as low as 0.15. The hydrodynamic diameter was determined by dynamic light scattering and the composition by atomic absorption spectroscopy and energy dispersive x-ray spectroscopy (EDS). Unusually low Au precursor supersaturation levels were utilized to nucleate and grow Au coatings on iron oxide relative to formation of pure Au nanoparticles. This approach produced unusually thin coatings, by lowering autocatalytic growth of Au on Au, as shown by transmission electron microscopy (TEM). Nearly all of the nanoparticles were attracted by a magnet indicating a minimal amount of pure Au particles The coatings were sufficiently thin to shift the surface plasmon resonance (SPR) to the near infrared (NIR), with large extinction coefficients., despite the small particle hydrodynamic diameters, observed from dynamic light scattering to be less than 60 nm. PMID:23238021

  12. Nucleation of Iron Oxide Nanoparticles Mediated by Mms6 Protein in Situ

    SciTech Connect

    Kashyap, Sanjay; Woehl, Taylor J; Liu, Xunpei; Mallapragada, Surya K; Prozorov, Tanya

    2014-09-23

    Biomineralization proteins are widely used as templating agents in biomimetic synthesis of a variety of organic–inorganic nanostructures. However, the role of the protein in controlling the nucleation and growth of biomimetic particles is not well understood, because the mechanism of the bioinspired reaction is often deduced from ex situ analysis of the resultant nanoscale mineral phase. Here we report the direct visualization of biomimetic iron oxide nanoparticle nucleation mediated by an acidic bacterial recombinant protein, Mms6, during an in situ reaction induced by the controlled addition of sodium hydroxide to solution-phase Mms6 protein micelles incubated with ferric chloride. Using in situ liquid cell scanning transmission electron microscopy we observe the liquid iron prenucleation phase and nascent amorphous nanoparticles forming preferentially on the surface of protein micelles. Our results provide insight into the early steps of protein-mediated biomimetic nucleation of iron oxide and point to the importance of an extended protein surface during nanoparticle formation.

  13. Preparation of iron oxide nanoparticles from FeCl3 solid powder using microemulsions

    NASA Astrophysics Data System (ADS)

    Nassar, Nashaat; Husein, Maen

    2006-05-01

    Nanoparticles of iron oxide were prepared by subjecting iron chloride powder to (w/o) microemulsions consisting of sodium bis(2-ethylhexyl) sulfosuccinate (AOT), isooctane and water. FeCl3 was first dissolved in the water pools of the microemulsion, and then reacted with NaOH added as an aqueous solution to form iron oxide. The amount of NaOH solution was limited so that single microemulsion phase is obtained. This technique serves as an in-situ nanoparticle preparation technique aimed at minimizing particle aggregation associated with particle transportation to required sites. In this study, the effects of AOT concentration and water to AOT mole ratio on the nanoparticle size were investigated. UV/Vis spectrophotometry and transmission electron microscopy (TEM) were used to measure the particle size distribution.

  14. Igneous Evolution of the Core and Mantle in the Parent Body of Group IVA Iron and Stony-Iron Meteorites

    NASA Astrophysics Data System (ADS)

    Scott, E. R. D.; McCoy, T. J.; Haack, H.; Taylor, G. J.

    1992-07-01

    peritectic liquids. Discussion: From the observed size and homogeneity of the Gibeon shower and our fractional crystallization modeling, we can infer that the parental liquid pool was at least many meters in size. Pools this big quickly sink through silicate (unless very reduced), so IVA metal very probably comes from a core. The wide range of metallographic cooling rates that is correlated with Ni concentration in IVA irons must therefore be an artefact. Liquids of pyroxene-silica compositions could be formed in the mantle (Prinz et al., 1984) but trapping them in the core at different stages of core crystallization seems very difficult. We prefer an origin for IVA stony irons by mixing olivine-pyroxene mantle material into the core during core solidification by processes like those that mixed olivine mantle into Fe,Ni cores to make pallasites, followed by addition of silica formed by oxidation of Si from the metal. Pieces of olivine-pyroxene, possibly in the form of a Brenham-like sponge, could be mixed into a crystallizing Fe,Ni core with about 2-4% S at temperatures around 1400 C. Pyroxene might be abundant in the mantle because small body size caused inefficient removal of trapped silicate liquid from an olivine cumulate. Alternatively, temperatures were never high enough to melt the mantle entirely. References: Haack H. and Scott E.R.D. (1992) Geochim. Cosmochim. Acta, submitted. Jones J.H. and Malvin (1990) Metall. Trans., 21B, 697-706. Prinz M., Nehru C.E., Delaney J.S., Fredriksson K., and Palme H. (1984) Meteoritics (abstract) 19, 291-292.

  15. Immobilization of Iron Nanoparticles on Multi Substrates and Its Reduction Removal of Chromium (VI) from Waste Streams

    EPA Science Inventory

    This article describes the in-situ synthesis and immobilization of iron nanoparticles on several substrates at room temperature using NaBH4 as a reducing agent and ascorbic acid as capping agent. The method is very effective in protecting iron nanoparticles from air oxidation for...

  16. Saturation of electrical resistivity of solid iron at Earth's core conditions.

    PubMed

    Pozzo, Monica; Alfè, Dario

    2016-01-01

    We report on the temperature dependence of the electrical resistivity of solid iron at high pressure, up to and including conditions likely to be found at the centre of the Earth. We have extended some of the calculations of the resistivities of pure solid iron we recently performed at Earth's core conditions (Pozzo et al. in Earth Planet Sci Lett 393:159-164, 2014) to lower temperature. We show that at low temperature the resistivity increases linearly with temperature, and saturates at high temperature. This saturation effect is well known as the Mott-Ioffe-Regel limit in metals, but has been largely ignored to estimate the resistivity of iron at Earth's core conditions. Recent experiments (Gomi et al. in Phys Earth Planet Int 224:88-103, 2013) coupled new high pressure data and saturation to predict the resitivity of iron and iron alloys at Earth's core conditions, and reported values up to three times lower than previous estimates, confirming recent first principles calculations (de Koker et al. in Proc Natl Acad Sci 109:4070-4073, 2012; Pozzo et al. in Nature 485:355-358, 2012, Phys Rev B 87:014110-10, 2013, Earth Planet Sci Lett 393:159-164, 2014; Davies et al. in Nat Geosci 8:678-685, 2015). The present results support the saturation effect idea. PMID:27026948

  17. Saturation of electrical resistivity of solid iron at Earth's core conditions.

    PubMed

    Pozzo, Monica; Alfè, Dario

    2016-01-01

    We report on the temperature dependence of the electrical resistivity of solid iron at high pressure, up to and including conditions likely to be found at the centre of the Earth. We have extended some of the calculations of the resistivities of pure solid iron we recently performed at Earth's core conditions (Pozzo et al. in Earth Planet Sci Lett 393:159-164, 2014) to lower temperature. We show that at low temperature the resistivity increases linearly with temperature, and saturates at high temperature. This saturation effect is well known as the Mott-Ioffe-Regel limit in metals, but has been largely ignored to estimate the resistivity of iron at Earth's core conditions. Recent experiments (Gomi et al. in Phys Earth Planet Int 224:88-103, 2013) coupled new high pressure data and saturation to predict the resitivity of iron and iron alloys at Earth's core conditions, and reported values up to three times lower than previous estimates, confirming recent first principles calculations (de Koker et al. in Proc Natl Acad Sci 109:4070-4073, 2012; Pozzo et al. in Nature 485:355-358, 2012, Phys Rev B 87:014110-10, 2013, Earth Planet Sci Lett 393:159-164, 2014; Davies et al. in Nat Geosci 8:678-685, 2015). The present results support the saturation effect idea.

  18. Studies on the effects of zerovalent iron nanoparticles on bacteria from the mangrove ecosystem.

    PubMed

    Kharangate-Lad, Amrita; Pereira, Flancy; Fernandes, Julio; Bhosle, Saroj

    2016-01-01

    Zerovalent iron (ZVI) nanoparticles are gaining popularity in bioremediation of contaminated ground water and antimicrobial studies. In this study, ZVI nanoparticles were synthesized by borohydride method. The effect of these nanoparticles to alter the cell surface hydrophobicity of mangrove bacteria was studied by bacterial adhesion to hydrocarbon assay. The effect of these nanoparticles on the growth and extracellular polymeric substances (EPS) of a novel bacterial strain Halobacillus trueperi MXM-16 from mangroves was evaluated by growing the culture in the presence of ZVI nanoparticles and SEM. The change in the emulsifying ability of the cell-free supernatant of Halobacillus trueperi MXM-16 when grown in media amended with ZVI nanoparticles was also investigated by spectrophotometric analysis.

  19. A pathway for the growth of core-shell Pt-Pd nanoparticles

    SciTech Connect

    Narula, Chaitanya Kumar; Yang, Xiaofan; Li, Chen; Pennycook, Stephen J; Lupini, Andrew R

    2015-10-12

    In this study, the aging of both Pt-Pd nanoparticles and core-shell Pt-Pd nanoparticles has been reported to result in alloying of Pt with Pd. In comparison to monometallic Pt catalysts, the growth of Pd-Pt bimetallics is slower; however, the mechanism of growth of particles and the mechanism by which Pd improves the hydrothermal durability of bimetallic Pd-Pt particles remains uncertain. In our work on hydrothermal aging of core-shell Pt-Pd nanoparticles, synthesized by solution methods, with varying Pd:Pt ratio of 1:4, 1:1, and 4:1, we compare the growth of core-shell Pt-Pd nanoparticles and find that particles grow by migrating and joining together. The unique feature of the observed growth is that Pd shells from both particles open up and join, allowing the cores to merge. At high temperatures, alloying occurs in good agreement with reports by other workers.

  20. Study of photodynamic activity of Au@SiO2 core-shell nanoparticles in vitro.

    PubMed

    Meena, K S; Dhanalekshmi, K I; Jayamoorthy, K

    2016-06-01

    Metal-semiconductor core-shell type Au@SiO2 nanoparticles were prepared by Stober's method. They were characterized by absorption, XRD, HR-TEM and EDAX techniques. The resulting modified core-shell nanoparticles shows that the formation of singlet oxygen, which was confirmed by ESR technique. The photohemolysis studies were carried out under two different experimental conditions. It is observed that the photohemolysis increases with concentration as well as light dose. Cell viability of the core-shell nanoparticles against HeLa cell lines were studied by MTT assay method. The outcomes of the present study indicate that, the Au@SiO2 core-shell nanoparticles are extremely stable with a very high photodynamic efficiency under visible light illumination.

  1. Liquid iron-sulfur alloys at outer core conditions by first-principles calculations

    NASA Astrophysics Data System (ADS)

    Umemoto, Koichiro; Hirose, Kei; Imada, Saori; Nakajima, Yoichi; Komabayashi, Tetsuya; Tsutsui, Satoshi; Baron, Alfred Q. R.

    2014-10-01

    We perform first-principles calculations to investigate liquid iron-sulfur alloys (Fe, Fe56S8, Fe52S12, and Fe48S16) under high-pressure and high-temperature (150-300 GPa and 4000-6000 K) conditions corresponding to the Earth's outer core. Considering only the density profile, the best match with the preliminary reference Earth model is by liquid Fe-14 wt % S (Fe50S14), assuming sulfur is the only light element. However, its bulk sound velocity is too high, in particular in the deep outer core, suggesting that another light component such as oxygen is required. An experimental check using inelastic X-ray scattering shows good agreement with the calculations. In addition, a present study demonstrates that the Birch's law does not hold for liquid iron-sulfur alloy, consistent with a previous report on pure liquid iron.

  2. [Application and advancement of magnetic iron-oxide nanoparticles in tumor-targeted therapy].

    PubMed

    Chen, Yue; Chen, Bao-An

    2010-01-01

    Recently, nanometer-sized magnetic particles have been intensively concerned and investigated due to their particularly large surface-to-volume ratio, quantum-size effect, magnetic character as well as their potential application in the area of bioscience and medicine. The most promising nanoparticles are magnetic iron oxide nanoparticles with appropriate surface modification, which have been widely used experimentally for numerous in vivo applications such as magnetic resonance imaging contrast enhancement, tissue repair, immunoassay, detoxification of biological fluids, drug delivery, hyperthermia and cell separation. To focus on one of the most important and fascinating subjects in nanobiotechnology, this review describes the current situation and development of magnetic iron oxide nanoparticles and their applications in drug delivery and hyperthermia in tumor-targeted therapy. The possible perspectives and some challenges to further development of these nanoparticles are also analyzed and discussed. PMID:20038325

  3. Study of Iron oxide nanoparticles using Mössbauer spectroscopy with a high velocity resolution

    NASA Astrophysics Data System (ADS)

    Oshtrakh, M. I.; Ushakov, M. V.; Šepelák, V.; Semionkin, V. A.; Morais, P. C.

    2016-01-01

    Iron oxide (magnetite and maghemite) nanoparticles developed for magnetic fluids were studied using Mössbauer spectroscopy with a high velocity resolution at 295 and 90 K. The recorded Mössbauer spectra have demonstrated that usual physical models based on octahedral and tetrahedral sites were not suitable for fitting. Alternatively, the Mössbauer spectra were nicely fitted using a large number of magnetic sextets. The obtained results showed that the Mössbauer spectra and the assessed parameters were different for nanoparticles as-prepared and dispersed in the dispersing fluid at 295 K. We claim that this finding is mainly due to the interaction of polar molecules with Iron cations at nanoparticle's surface or due to the surface coating using carboxylic-terminated molecules. It is assumed that the large number of spectral components may be related to complexity of the nanoparticle's characteristics and deviations from stoichiometry, including in the latter the influence of the oxidation of magnetite towards maghemite.

  4. Mechanisms of enhanced osteoblast gene expression in the presence of hydroxyapatite coated iron oxide magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Tran, Nhiem; Hall, Douglas; Webster, Thomas J.

    2012-11-01

    Hydroxyapatite (HA) coated iron oxide (Fe3O4) magnetic nanoparticles have been shown to enhance osteoblast (bone forming cells) proliferation and osteoblast differentiation into calcium depositing cells (through increased secretion of alkaline phosphatase, collagen and calcium deposition) compared to control samples without nanoparticles. Such nanoparticles are, thus, very promising for numerous orthopedic applications including magnetically directed osteoporosis treatment. The objective of the current study was to elucidate the mechanisms of the aforementioned improved osteoblast responses in the presence of HA coated Fe3O4 nanoparticles. Results demonstrated large amounts of fibronectin (a protein known to increase osteoblast functions) adsorption on HA coated Fe3O4 nanoparticles. Specifically, fibronectin adsorption almost doubled when HA coated Fe3O4 nanoparticle concentrations increased from 12.5 to 100 μg ml-1, and from 12.5 to 200 μg ml-1, a four fold increase was observed. Results also showed greater osteoblast gene regulation (specifically, osteocalcin, type I collagen and cbfa-1) in the presence of HA coated Fe3O4 nanoparticles. Collectively, these results provide a mechanism for the observed enhanced osteoblast functions in the presence of HA coated iron oxide nanoparticles, allowing their further investigation for a number of orthopedic applications.

  5. Colloidal Stability and Monodispersible Magnetic Iron Oxide Nanoparticles in Biotechnology Application

    NASA Astrophysics Data System (ADS)

    Shamili, K.; Rajesh, E. M.; Rajendran, R.; Madhan Shankar, S. R.; Elango, M.; Abitha Devi, N.

    2013-02-01

    Magnetic iron oxide nanoparticles are promising material for various biological applications. In the recent decades, magnetic iron oxide nanoparticles (MNPs) have great attention in biomedical applications such as drug delivery, magnetic resonance imaging (MRI) and magnetic fluid hyperthermia (MFH). This review focuses on the colloidal stability and monodispersity properties of MNPs, which pay more attention toward biomedical applications. The simplest and the most promising method for the synthesis of MNPs is co-precipitation. The biocompatible MNPs are more interested in MRI application. This review also apportions synthesis, characterization and applications of MNP in biological and biomedical as theranostics and imaging.

  6. Predictable Heating and Positive MRI Contrast from a Mesoporous Silica-Coated Iron Oxide Nanoparticle.

    PubMed

    Hurley, Katie R; Ring, Hattie L; Etheridge, Michael; Zhang, Jinjin; Gao, Zhe; Shao, Qi; Klein, Nathan D; Szlag, Victoria M; Chung, Connie; Reineke, Theresa M; Garwood, Michael; Bischof, John C; Haynes, Christy L

    2016-07-01

    Iron oxide nanoparticles have great potential as diagnostic and therapeutic agents in cancer and other diseases; however, biological aggregation severely limits their function in vivo. Aggregates can cause poor biodistribution, reduced heating capability, and can confound their visualization and quantification by magnetic resonance imaging (MRI). Herein, we demonstrate that the incorporation of a functionalized mesoporous silica shell can prevent aggregation and enable the practical use of high-heating, high-contrast iron oxide nanoparticles in vitro and in vivo. Unmodified and mesoporous silica-coated iron oxide nanoparticles were characterized in biologically relevant environments including phosphate buffered saline, simulated body fluid, whole mouse blood, lymph node carcinoma of prostate (LNCaP) cells, and after direct injection into LNCaP prostate cancer tumors in nude mice. Once coated, iron oxide nanoparticles maintained colloidal stability along with high heating and relaxivity behaviors (SARFe = 204 W/g Fe at 190 kHz and 20 kA/m and r1 = 6.9 mM(-1) s(-1) at 1.4 T). Colloidal stability and minimal nonspecific cell uptake allowed for effective heating in salt and agarose suspensions and strong signal enhancement in MR imaging in vivo. These results show that (1) aggregation can lower the heating and imaging performance of magnetic nanoparticles and (2) a coating of functionalized mesoporous silica can mitigate this issue, potentially improving clinical planning and practical use. PMID:26991550

  7. Carbon Solubility in Silicon-Iron-Bearing Metals during Core Formation on Mercury

    NASA Technical Reports Server (NTRS)

    Vander Kaaden, Kathleen E.; McCubbin, Francis M.; Ross, D. Kent; Rapp, Jennifer F.; Danielson, Lisa R.; Keller, Lindsay P.; Righter, Kevin

    2016-01-01

    Recent results obtained from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft showed the surface of Mercury has high S abundances (approximately 4 wt%) and low Iron(II) Oxide abundances (less than 2 wt%). Based on these extreme values, the oxygen fugacity of Mercury's surface materials was estimated to be approximately 3 to 7 log(sub 10) units below the IW buffer (Delta IW-3 to Delta IW-7). This highly reducing nature of the planet has resulted in a large core and relatively thin mantle, extending to only approximately 420 km depth (corresponding to a core-mantle boundary pressure of approximately 4-7 GPa) within the planet. Furthermore, MESSENGER results have suggested the presence of carbon on the surface of the planet. Previous experimental results from have also suggested the possibility of a primary floatation crust on Mercury composed of graphite, produced after a global magma ocean event. With these exotic conditions of this compositional end-member planet, it begs the question, what is the core composition of Mercury? Although no definitive conclusion has been reached, previous studies have made advances towards answering this question. Riner et al. and Chen et al. looked at iron sulfide systems and implemented various crystallization and layered core scenarios to try and determine the composition and structure of Mercury's core. Malavergne et al. examined core crystallization scenarios in the presence of sulfur and silicon. Hauck et al. used the most recent geophysical constraints from the MESSENGER spacecraft to model the internal structure of Mercury, including the core, in a iron-sulfur-silicon system. More recently, Chabot et al. conducted a series of metal-silicate partitioning experiments in a iron-sulfur-silicon system. These results showed the core of Mercury has the potential to contain more than 15 wt% silicon. However, with the newest results from MESSENGER's low altitude campaign, carbon is another

  8. Surfactant free superparamagnetic iron oxide nanoparticles for stable ferrofluids in physiological solutions.

    PubMed

    Mandel, K; Straßer, M; Granath, T; Dembski, S; Sextl, G

    2015-02-18

    A process is reported to obtain a nanoparticle sol from co-precipitated iron oxide particles without using any surfactant. The sol - a true ferrofluid - is not only stable over a wide range of pH but also in physiological solutions. This is a decisive step towards biomedical applications where nanoparticle agglomeration could so far only be prevented by using unwanted surfactants. PMID:25580829

  9. Glioma-targeted superparamagnetic iron oxide nanoparticles as drug-carrying vehicles for theranostic effects

    NASA Astrophysics Data System (ADS)

    Xu, He-Lin; Mao, Kai-Li; Huang, Yin-Ping; Yang, Jing-Jing; Xu, Jie; Chen, Pian-Pian; Fan, Zi-Liang; Zou, Shuang; Gao, Zheng-Zheng; Yin, Jia-Yu; Xiao, Jian; Lu, Cui-Tao; Zhang, Bao-Lin; Zhao, Ying-Zheng

    2016-07-01

    Multifunctional nanoparticles capable of the specific delivery of therapeutics to diseased cells and the real-time imaging of these sites have the potential to improve cancer treatment through personalized therapy. In this study, we have proposed a multifunctional nanoparticle that integrate magnetic targeting, drug-carrier functionality and real-time MRI imaging capabilities in one platform for the theranostic treatment of tumors. The multifunctional nanoparticle was designed with a superparamagnetic iron oxide core and a multifunctional shell composed of PEG/PEI/polysorbate 80 (Ps 80) and was used to encapsulate DOX. DOX-loaded multifunctional nanoparticles (DOX@Ps 80-SPIONs) with a Dh of 58.0 nm, a zeta potential of 28.0 mV, and a drug loading content of 29.3% presented superior superparamagnetic properties with a saturation magnetization (Ms) of 24.1 emu g-1. The cellular uptake of DOX@Ps 80-SPIONs by C6 cells under a magnetic field was significantly enhanced over that of free DOX in solution, resulting in stronger in vitro cytotoxicity. The real-time therapeutic outcome of DOX@Ps 80-SPIONs was easily monitored by MRI. Furthermore, the negative contrast enhancement effect of the nanoparticles was confirmed in glioma-bearing rats. Prussian blue staining and ex vivo DOX fluorescence assays showed that the magnetic Ps 80-SPIONs and encapsulated DOX were delivered to gliomas by imposing external magnetic fields, indicating effective magnetic targeting. Due to magnetic targeting and Ps 80-mediated endocytosis, DOX@Ps 80-SPIONs in the presence of a magnetic field led to the complete suppression of glioma growth in vivo at 28 days after treatment. The therapeutic mechanism of DOX@Ps 80-SPIONs acted by inducing apoptosis through the caspase-3 pathway. Finally, DOX@Ps 80-SPIONs' safety at therapeutic dosage was verified using pathological HE assays of the heart, liver, spleen, lung and kidney. Multifunctional SPIONs could be used as potential carriers for the

  10. Glioma-targeted superparamagnetic iron oxide nanoparticles as drug-carrying vehicles for theranostic effects

    NASA Astrophysics Data System (ADS)

    Xu, He-Lin; Mao, Kai-Li; Huang, Yin-Ping; Yang, Jing-Jing; Xu, Jie; Chen, Pian-Pian; Fan, Zi-Liang; Zou, Shuang; Gao, Zheng-Zheng; Yin, Jia-Yu; Xiao, Jian; Lu, Cui-Tao; Zhang, Bao-Lin; Zhao, Ying-Zheng

    2016-07-01

    Multifunctional nanoparticles capable of the specific delivery of therapeutics to diseased cells and the real-time imaging of these sites have the potential to improve cancer treatment through personalized therapy. In this study, we have proposed a multifunctional nanoparticle that integrate magnetic targeting, drug-carrier functionality and real-time MRI imaging capabilities in one platform for the theranostic treatment of tumors. The multifunctional nanoparticle was designed with a superparamagnetic iron oxide core and a multifunctional shell composed of PEG/PEI/polysorbate 80 (Ps 80) and was used to encapsulate DOX. DOX-loaded multifunctional nanoparticles (DOX@Ps 80-SPIONs) with a Dh of 58.0 nm, a zeta potential of 28.0 mV, and a drug loading content of 29.3% presented superior superparamagnetic properties with a saturation magnetization (Ms) of 24.1 emu g-1. The cellular uptake of DOX@Ps 80-SPIONs by C6 cells under a magnetic field was significantly enhanced over that of free DOX in solution, resulting in stronger in vitro cytotoxicity. The real-time therapeutic outcome of DOX@Ps 80-SPIONs was easily monitored by MRI. Furthermore, the negative contrast enhancement effect of the nanoparticles was confirmed in glioma-bearing rats. Prussian blue staining and ex vivo DOX fluorescence assays showed that the magnetic Ps 80-SPIONs and encapsulated DOX were delivered to gliomas by imposing external magnetic fields, indicating effective magnetic targeting. Due to magnetic targeting and Ps 80-mediated endocytosis, DOX@Ps 80-SPIONs in the presence of a magnetic field led to the complete suppression of glioma growth in vivo at 28 days after treatment. The therapeutic mechanism of DOX@Ps 80-SPIONs acted by inducing apoptosis through the caspase-3 pathway. Finally, DOX@Ps 80-SPIONs' safety at therapeutic dosage was verified using pathological HE assays of the heart, liver, spleen, lung and kidney. Multifunctional SPIONs could be used as potential carriers for the

  11. Size-controlled synthesis of superparamagnetic iron oxide nanoparticles and their surface coating by gold for biomedical applications

    NASA Astrophysics Data System (ADS)

    Maleki, H.; Simchi, A.; Imani, M.; Costa, B. F. O.

    2012-11-01

    The size mono-dispersity, saturation magnetization, and surface chemistry of magnetic nanoparticles (NPs) are recognized as critical factors for efficient biomedical applications. Here, we performed modified water-in-oil inverse nano-emulsion procedure for preparation of stable colloidal superparamagnetic iron oxide NPs (SPIONs) with high saturation magnetization. To achieve mono-dispersed SPIONs, optimization process was probed on several important factors including molar ratio of iron salts [Fe3+ and Fe2+], the concentration of ammonium hydroxide as reducing agent, and molar ratio of water to surfactant. The biocompatibility of the obtained NPs, at various concentrations, was evaluated via MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay and the results showed that the NPs were non-toxic at concentrations <0.1 mg/mL. Surface functionalization was performed by conformal coating of the NPs with a thin shell of gold (˜4 nm) through chemical reduction of attached gold salts at the surface of the SPIONs. The Fe3O4 core/Au shell particles demonstrate strong plasmon resonance absorption and can be separated from solution using an external magnetic field. Experimental data from both physical and chemical determinations of the changes in particle size, surface plasmon resonance optical band, phase components, core-shell surface composition, and magnetic properties have confirmed the formation of the mono-dispersed core-shell nanostructure.

  12. Understanding the role of iron in the magnetism of Fe doped ZnO nanoparticles.

    PubMed

    Beltrán, J J; Barrero, C A; Punnoose, A

    2015-06-21

    The actual role of transition metals like iron in the room temperature ferromagnetism (RTFM) of Fe doped ZnO nanoparticles is still an unsolved problem. While some studies concluded that the Fe ions participate in the magnetic interaction, others in contrast do not believe Fe to play a direct role in the magnetic exchange interaction. To contribute to the understanding of this issue, we have carefully investigated the structural, optical, vibrational and magnetic properties of sol-gel synthesized Zn1-xFexO (0 < x < 0.10) nanoparticles. No Fe(2+) was detected in any sample. We found that high spin Fe(3+) ions are substitutionally incorporated at the Zn(2+) in the tetrahedral-core sites and in pseudo-octahedral surface sites in ZnO. Superficial OH(-) was observed in all samples. For x ≤ 0.03, an increment in Fe doping concentration decreased a and c lattice parameters, average Zn-O bond length, average crystallite size and band gap; while it increased the degree of distortion and quadrupole splitting. Undoped ZnO nanoparticles exhibited very weak RTFM with a saturation magnetization (Ms) of ∼0.47 memu g(-1) and this value increased to ∼2.1 memu g(-1) for Zn0.99Fe0.01O. Very interestingly, the Ms for Zn0.99Fe0.01O and Zn0.97Fe0.03O increased by a factor of about ∼2.3 by increasing annealing for 1 h to 3 h. For x ≥ 0.05, ferrimagnetic disordered spinel ZnFe2O4 was formed and this phase was found to become more ordered with increasing annealing time. Fe does not contribute directly to the RTFM, but its presence promoted the formation of additional single charged oxygen vacancies, zinc vacancies, and more oxygen-ended polar terminations at the nanoparticle surface. These defects, which are mainly superficial, altered the electronic structure and are considered as the main sources of the observed ferromagnetism. PMID:25994044

  13. Magnetite and zero-valent iron nanoparticles for the remediation of uranium contaminated environmental water.

    PubMed

    Crane, R A; Dickinson, M; Popescu, I C; Scott, T B

    2011-04-01

    The current work presents a comparative and site specific study for the application of zero-valent iron nanoparticles (nano-Fe(0)) and magnetite nanoparticles (nano-Fe(3)O(4)) for the removal of U from carbonate-rich environmental water taken from the Lişava valley, Banat, Romania. Nanoparticles were introduced to the Lişava water under surface and deep aquifer oxygen conditions, with a U(VI)-only solution studied as a simple system comparator. Thebatch systems were analysed over an 84 day reaction period, during which the liquid and nanoparticulate solids were periodically sampled to determine chemical evolution of the solutions and particulates. Results indicated that U was removed by all nano-Fe(0) systems to <10 μg L(-1) (>98% removal) within 2 h of reaction, below EPA and WHO specified drinking water regulations. Similar U concentrations were maintained until approximately 48 h. X-ray photoelectron spectroscopy analysis of the nanoparticulate solids confirmed partial chemical reduction of U(VI) to U(IV) concurrent with Fe oxidation. In contrast, nano-Fe(3)O(4) failed to achieve >20% U removal from the Lişava water. Whilst the outer surface of both the nano-Fe(0) and nano-Fe(3)O(4) was initially near-stoichiometric magnetite, the greater performance exhibited by nano-Fe(0) is attributed to the presence of a Fe(0) core for enhanced aqueous reactivity, sufficient to achieve near-total removal of aqueous U despite any competing reactions within the carbonate-rich Lişava water. Over extended reaction periods (>1 week) the chemically simple U(VI)-only solution treated using nano-Fe(0) exhibited near-complete and maintained U removal. In contrast, appreciable U re-release was recorded for the Lişava water solutions treated using nano-Fe(0). This behaviour is attributed to the high stability of U in the presence of ligands (predominantly carbonate) within the Lişava water, inducing preferential re-release to the aqueous phase during nano-Fe(0) corrosion. The

  14. Methods of preparation and modification of advanced zero-valent iron nanoparticles, their properties and application in water treatment technologies

    NASA Astrophysics Data System (ADS)

    Filip, Jan; Kašlík, Josef; Medřík, Ivo; Petala, Eleni; Zbořil, Radek; Slunský, Jan; Černík, Miroslav; Stavělová, Monika

    2014-05-01

    Zero-valent iron nanoparticles are commonly used in modern water treatment technologies. Compared to conventionally-used macroscopic iron or iron microparticles, the using of nanoparticles has the advantages given mainly by their generally large specific surface area (it drives their high reactivity and/or sorption capacity), small dimensions (it allows their migration e.g. in ground water), and particular physical and chemical properties. Following the applications of zero-valent iron particles in various pilot tests, there arose several critical suggestions for improvements of used nanomaterials and for development of new generation of reactive nanomaterials. In the presentation, the methods of zero-valent iron nanoparticles synthesis will be summarized with a special attention paid to the thermally-induced solid-state reaction allowing preparation of zero-valent iron nanoparticles in an industrial scale. Moreover, the method of thermal reduction of iron-oxide precursors enables to finely tune the critical parameters (mainly particle size and morphology, specific surface area, surface chemistry of nanoparticles etc.) of resulting zero-valet iron nanoparticles. The most important trends of advanced nanoparticles development will be discussed: (i) surface modification of nanomaterilas, (ii) development of nanocomposites and (iii) development of materials for combined reductive-sorption technologies. Laboratory testing of zero-valent iron nanoparticles reactivity and migration will be presented and compared with the field observations: the advanced zero-valent iron nanoparticles were used for groundwater treatment at the locality contaminated by chlorinated hydrocarbons (VC, DCE, TCE and PCE) and reacted nanoparticles were extracted from the sediments for their fate assessment. The authors gratefully acknowledge the support by the Technology Agency of the Czech Republic "Competence Centres" (project No. TE01020218) and the EU FP7 (project NANOREM).

  15. Iron overload by Superparamagnetic Iron Oxide Nanoparticles is a High Risk Factor in Cirrhosis by a Systems Toxicology Assessment

    PubMed Central

    Wei, Yushuang; Zhao, Mengzhu; Yang, Fang; Mao, Yang; Xie, Hang; Zhou, Qibing

    2016-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) as a contrast agent have been widely used in magnetic resonance imaging for tumor diagnosis and theranostics. However, there has been safety concern of SPIONs with cirrhosis related to excess iron-induced oxidative stress. In this study, the impact of iron overload by SPIONs was assessed on a mouse cirrhosis model. A single dose of SPION injection at 0.5 or 5 mg Fe/kg in the cirrhosis group induced a septic shock response at 24 h with elevated serum levels of liver and kidney function markers and extended impacts over 14 days including high levels of serum cholesterols and persistent low serum iron level. In contrast, full restoration of liver functions was found in the normal group with the same dosages over time. Analysis with PCR array of the toxicity pathways revealed the high dose of SPIONs induced significant expression changes of a distinct subset of genes in the cirrhosis liver. All these results suggested that excess iron of the high dose of SPIONs might be a risk factor for cirrhosis because of the marked impacts of elevated lipid metabolism, disruption of iron homeostasis and possibly, aggravated loss of liver functions. PMID:27357559

  16. Iron overload by Superparamagnetic Iron Oxide Nanoparticles is a High Risk Factor in Cirrhosis by a Systems Toxicology Assessment.

    PubMed

    Wei, Yushuang; Zhao, Mengzhu; Yang, Fang; Mao, Yang; Xie, Hang; Zhou, Qibing

    2016-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) as a contrast agent have been widely used in magnetic resonance imaging for tumor diagnosis and theranostics. However, there has been safety concern of SPIONs with cirrhosis related to excess iron-induced oxidative stress. In this study, the impact of iron overload by SPIONs was assessed on a mouse cirrhosis model. A single dose of SPION injection at 0.5 or 5 mg Fe/kg in the cirrhosis group induced a septic shock response at 24 h with elevated serum levels of liver and kidney function markers and extended impacts over 14 days including high levels of serum cholesterols and persistent low serum iron level. In contrast, full restoration of liver functions was found in the normal group with the same dosages over time. Analysis with PCR array of the toxicity pathways revealed the high dose of SPIONs induced significant expression changes of a distinct subset of genes in the cirrhosis liver. All these results suggested that excess iron of the high dose of SPIONs might be a risk factor for cirrhosis because of the marked impacts of elevated lipid metabolism, disruption of iron homeostasis and possibly, aggravated loss of liver functions. PMID:27357559

  17. Superparamagnetic iron oxide nanoparticles incorporated into silica nanoparticles by inelastic collision via ultrasonic field: Role of colloidal stability

    NASA Astrophysics Data System (ADS)

    Sodipo, Bashiru Kayode; Azlan, Abdul Aziz

    2015-04-01

    Superparamagnetic iron oxide nanoparticles (SPION)/Silica composite nanoparticles were prepared by ultrasonically irradiating colloidal suspension of silica and SPION mixture. Both silica and SPION were synthesized independently via co-precipitation and sol-gel method, respectively. Their mixtures were sonicated at different pH between 3 and 5. Electrophoresis measurement and other physicochemical analyses of the products demonstrate that at lower pH SPION was found incorporated into the silica. However, at pH greater than 4, SPION was unstable and unable to withstand the turbulence flow and shock wave from the ultrasonic field. Results suggest that the formation of the SPION/silica composite nanoparticles is strongly related to the inelastic collision induced by ultrasonic irradiation. More so, the formation the composite nanoparticles via the ultrasonic field are dependent on the zeta potential and colloidal stability of the particles.

  18. Superparamagnetic iron oxide nanoparticles incorporated into silica nanoparticles by inelastic collision via ultrasonic field: Role of colloidal stability

    SciTech Connect

    Sodipo, Bashiru Kayode; Azlan, Abdul Aziz

    2015-04-24

    Superparamagnetic iron oxide nanoparticles (SPION)/Silica composite nanoparticles were prepared by ultrasonically irradiating colloidal suspension of silica and SPION mixture. Both silica and SPION were synthesized independently via co-precipitation and sol-gel method, respectively. Their mixtures were sonicated at different pH between 3 and 5. Electrophoresis measurement and other physicochemical analyses of the products demonstrate that at lower pH SPION was found incorporated into the silica. However, at pH greater than 4, SPION was unstable and unable to withstand the turbulence flow and shock wave from the ultrasonic field. Results suggest that the formation of the SPION/silica composite nanoparticles is strongly related to the inelastic collision induced by ultrasonic irradiation. More so, the formation the composite nanoparticles via the ultrasonic field are dependent on the zeta potential and colloidal stability of the particles.

  19. Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Hsu, Chiajen; Huang, Chienwen; Hao, Yaowu; Liu, Fuqiang

    2013-03-01

    A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became highly porous. After the Pd shell formed on these Au nanospheres, the morphology and structure of the Au/Pd nanoparticles varied and hence significantly affected the catalytic properties. The Au/Pd nanoparticles synthesized with reduced Au concentrations showed higher formic acid oxidation activity (0.93 mA cm-2 at 0.3 V) than the commercial Pd black (0.85 mA cm-2 at 0.3 V), suggesting a promising candidate as fuel cell catalysts. In addition, the Au/Pd nanoparticles displayed lower CO-stripping potential, improved stability, and higher durability compared to the Pd black due to their unique core-shell structures tuned by Au core morphologies.

  20. Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation.

    PubMed

    Hsu, Chiajen; Huang, Chienwen; Hao, Yaowu; Liu, Fuqiang

    2013-03-01

    A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became highly porous. After the Pd shell formed on these Au nanospheres, the morphology and structure of the Au/Pd nanoparticles varied and hence significantly affected the catalytic properties. The Au/Pd nanoparticles synthesized with reduced Au concentrations showed higher formic acid oxidation activity (0.93 mA cm-2 at 0.3 V) than the commercial Pd black (0.85 mA cm-2 at 0.3 V), suggesting a promising candidate as fuel cell catalysts. In addition, the Au/Pd nanoparticles displayed lower CO-stripping potential, improved stability, and higher durability compared to the Pd black due to their unique core-shell structures tuned by Au core morphologies.

  1. Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation

    PubMed Central

    2013-01-01

    A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet–visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became highly porous. After the Pd shell formed on these Au nanospheres, the morphology and structure of the Au/Pd nanoparticles varied and hence significantly affected the catalytic properties. The Au/Pd nanoparticles synthesized with reduced Au concentrations showed higher formic acid oxidation activity (0.93 mA cm-2 at 0.3 V) than the commercial Pd black (0.85 mA cm-2 at 0.3 V), suggesting a promising candidate as fuel cell catalysts. In addition, the Au/Pd nanoparticles displayed lower CO-stripping potential, improved stability, and higher durability compared to the Pd black due to their unique core-shell structures tuned by Au core morphologies. PMID:23452438

  2. SOLUBILITY OF IRON IN METALLIC HYDROGEN AND STABILITY OF DENSE CORES IN GIANT PLANETS

    SciTech Connect

    Wahl, Sean M.; Wilson, Hugh F.; Militzer, Burkhard

    2013-08-20

    The formation of the giant planets in our solar system, and likely a majority of giant exoplanets, is most commonly explained by the accretion of nebular hydrogen and helium onto a large core of terrestrial-like composition. The fate of this core has important consequences for the evolution of the interior structure of the planet. It has recently been shown that H{sub 2}O, MgO, and SiO{sub 2} dissolve in liquid metallic hydrogen at high temperature and pressure. In this study, we perform ab initio calculations to study the solubility of an innermost metallic core. We find dissolution of iron to be strongly favored above 2000 K over the entire pressure range (0.4-4 TPa) considered. We compare with and summarize the results for solubilities on other probable core constituents. The calculations imply that giant planet cores are in thermodynamic disequilibrium with surrounding layers, promoting erosion and redistribution of heavy elements. Differences in solubility behavior between iron and rock may influence evolution of interiors, particularly for Saturn-mass planets. Understanding the distribution of iron and other heavy elements in gas giants may be relevant in understanding mass-radius relationships, as well as deviations in transport properties from pure hydrogen-helium mixtures.

  3. Effect of superconducting solenoid model cores on spanwise iron magnet roll control

    NASA Technical Reports Server (NTRS)

    Britcher, C. P.

    1985-01-01

    Compared with conventional ferromagnetic fuselage cores, superconducting solenoid cores appear to offer significant reductions in the projected cost of a large wind tunnel magnetic suspension and balance system. The provision of sufficient magnetic roll torque capability has been a long-standing problem with all magnetic suspension and balance systems; and the spanwise iron magnet scheme appears to be the most powerful system available. This scheme utilizes iron cores which are installed in the wings of the model. It was anticipated that the magnetization of these cores, and hence the roll torque generated, would be affected by the powerful external magnetic field of the superconducting solenoid. A preliminary study has been made of the effect of the superconducting solenoid fuselage model core concept on the spanwise iron magnet roll torque generation schemes. Computed data for one representative configuration indicate that reductions in available roll torque occur over a range of applied magnetic field levels. These results indicate that a 30-percent increase in roll electromagnet capacity over that previously determined will be required for a representative 8-foot wind tunnel magnetic suspension and balance system design.

  4. Optimization of preparation of chitosan-coated iron oxide nanoparticles for biomedical applications by chemometrics approaches

    NASA Astrophysics Data System (ADS)

    Honary, Soheila; Ebrahimi, Pouneh; Rad, Hossein Asgari; Asgari, Mahsa

    2013-08-01

    Functionalized magnetic nanoparticles are used in several biomedical applications, such as drug delivery, magnetic cell separation, and magnetic resonance imaging. Size and surface properties of iron oxide nanoparticles are the two important factors which could dramatically affect the nanoparticle efficiency as well as their stability. In this study, the chemometrics approach was applied to optimize the coating process of iron oxide nanoparticles. To optimize the size of nanoparticles, the effect of two experimental parameters on size was investigated by means of multivariate analysis. The factors considered were chitosan molecular weight and chitosan-to-tripolyphosphate concentration ratio. The experiments were performed according to face-centered cube central composite response surface design. A second-order regression model was obtained which characterized by both descriptive and predictive abilities. The method was optimized with respect to the percent of Z average diameter's increasing after coating as response. It can be concluded that experimental design provides a suitable means of optimizing and testing the robustness of iron oxide nanoparticle coating method.

  5. Superparamagnetic iron oxide nanoparticles as radiosensitizer via enhanced reactive oxygen species formation

    SciTech Connect

    Klein, Stefanie; Sommer, Anja; Distel, Luitpold V.R.; Neuhuber, Winfried; Kryschi, Carola

    2012-08-24

    Highlights: Black-Right-Pointing-Pointer Ultrasmall citrate-coated SPIONs with {gamma}Fe{sub 2}O{sub 3} and Fe{sub 3}O{sub 4} structure were prepared. Black-Right-Pointing-Pointer SPIONs uptaken by MCF-7 cells increase the ROS production for about 240%. Black-Right-Pointing-Pointer The SPION induced ROS production is due to released iron ions and catalytically active surfaces. Black-Right-Pointing-Pointer Released iron ions and SPION surfaces initiate the Fenton and Haber-Weiss reaction. Black-Right-Pointing-Pointer X-ray irradiation of internalized SPIONs leads to an increase of catalytically active surfaces. -- Abstract: Internalization of citrate-coated and uncoated superparamagnetic iron oxide nanoparticles by human breast cancer (MCF-7) cells was verified by transmission electron microscopy imaging. Cytotoxicity studies employing metabolic and trypan blue assays manifested their excellent biocompatibility. The production of reactive oxygen species in iron oxide nanoparticle loaded MCF-7 cells was explained to originate from both, the release of iron ions and their catalytically active surfaces. Both initiate the Fenton and Haber-Weiss reaction. Additional oxidative stress caused by X-ray irradiation of MCF-7 cells was attributed to the increase of catalytically active iron oxide nanoparticle surfaces.

  6. Impact of magnetic field parameters and iron oxide nanoparticle properties on heat generation for use in magnetic hyperthermia

    PubMed Central

    Shah, Rhythm R.; Davis, Todd P.; Glover, Amanda L.; Nikles, David E.; Brazel, Christopher S.

    2015-01-01

    Heating of nanoparticles (NPs) using an AC magnetic field depends on several factors, and optimization of these parameters can improve the efficiency of heat generation for effective cancer therapy while administering a low NP treatment dose. This study investigated magnetic field strength and frequency, NP size, NP concentration, and solution viscosity as important parameters that impact the heating efficiency of iron oxide NPs with magnetite (Fe3O4) and maghemite (γ-Fe2O3) crystal structures. Heating efficiencies were determined for each experimental setting, with specific absorption rates (SARs) ranging from 3.7 to 325.9 W/g Fe. Magnetic heating was conducted on iron oxide NPs synthesized in our laboratories (with average core sizes of 8, 11, 13, and 18 nm), as well as commercially-available iron oxides (with average core sizes of 8, 9, and 16 nm). The experimental magnetic coil system made it possible to isolate the effect of magnetic field parameters and independently study the effect on heat generation. The highest SAR values were found for the 18 nm synthesized particles and the maghemite nanopowder. Magnetic field strengths were applied in the range of 15.1 to 47.7 kA/m, with field frequencies ranging from 123 to 430 kHz. The best heating was observed for the highest field strengths and frequencies tested, with results following trends predicted by the Rosensweig equation. An increase in solution viscosity led to lower heating rates in nanoparticle solutions, which can have significant implications for the application of magnetic fluid hyperthermia in vivo. PMID:25960599

  7. Impact of magnetic field parameters and iron oxide nanoparticle properties on heat generation for use in magnetic hyperthermia

    NASA Astrophysics Data System (ADS)

    Shah, Rhythm R.; Davis, Todd P.; Glover, Amanda L.; Nikles, David E.; Brazel, Christopher S.

    2015-08-01

    Heating of nanoparticles (NPs) using an AC magnetic field depends on several factors, and optimization of these parameters can improve the efficiency of heat generation for effective cancer therapy while administering a low NP treatment dose. This study investigated magnetic field strength and frequency, NP size, NP concentration, and solution viscosity as important parameters that impact the heating efficiency of iron oxide NPs with magnetite (Fe3O4) and maghemite (γ-Fe2O3) crystal structures. Heating efficiencies were determined for each experimental setting, with specific absorption rates (SARs) ranging from 3.7 to 325.9 W/g Fe. Magnetic heating was conducted on iron oxide NPs synthesized in our laboratories (with average core sizes of 8, 11, 13, and 18 nm), as well as commercially-available iron oxides (with average core sizes of 8, 9, and 16 nm). The experimental magnetic coil system made it possible to isolate the effect of magnetic field parameters and independently study the effect on heat generation. The highest SAR values were found for the 18 nm synthesized particles and the maghemite nanopowder. Magnetic field strengths were applied in the range of 15.1-47.7 kA/m, with field frequencies ranging from 123 to 430 kHz. The best heating was observed for the highest field strengths and frequencies tested, with results following trends predicted by the Rosensweig equation. An increase in solution viscosity led to lower heating rates in nanoparticle solutions, which can have significant implications for the application of magnetic fluid hyperthermia in vivo.

  8. Watermelon-like iron nanoparticles: Cr doping effect on magnetism and magnetization interaction reversal

    SciTech Connect

    Kaur, Maninder; Dai, Qilin; Bowden, Mark E.; Engelhard, Mark H.; Wu, Yaqiao; Tang, Jinke; Qiang, You

    2013-06-26

    Chromium (Cr) forms a solid solution with iron (Fe) lattice when doped in core-shell iron -iron oxide nanocluster (NC) and shows a mixed phase of sigma (σ) FeCr and bcc Fe. The Cr dopant affects heavily the magnetization and magnetic reversal process, and causes the hysteresis loop to shrink near the zero field axis. Dramatic transformation happens from dipolar interaction (0 at. % Cr) to strong exchange interaction (8 at. % of Cr) is confirmed from the Henkel plot and delta M plot, and is explained by a water-melon model of core-shell NC system.

  9. Gold nanoparticle localization at the core surface by using thermosensitive core-shell particles as a template.

    PubMed

    Suzuki, Daisuke; Kawaguchi, Haruma

    2005-12-01

    We report novel thermosensitive hybrid core-shell particles via in situ gold nanoparticle formation using thermosensitive core-shell particles as a template. This method for the in situ synthesis of gold nanoparticles with microgel interiors offers the advantage of eliminating or significantly reducing particle aggregation. In addition, by using thermosensitive microgel structures in which the shell has thermosensitive and gel properties in water--whereas the core itself is a water-insoluble polymer--we were able to synthesize the gold nanoparticles only at the surface of the core, which had reactive sites to bind metal ions. After the gold nanoparticles were synthesized, electroless gold plating was carried out to control the thickness of the gold nanoshells. The dispersions of the obtained hybrid particles were characterized by dynamic light scattering and UV-vis absorption spectroscopy, and the dried particles were also observed by electron microscopy. Adaptation of the technique shown here will create a number of applications as optical, electronic, and biomedical functional materials. PMID:16316147

  10. Evaluation of High-Yield Purification Methods on Monodisperse PEG-Grafted Iron Oxide Nanoparticles.

    PubMed

    Lassenberger, Andrea; Bixner, Oliver; Gruenewald, Tilman; Lichtenegger, Helga; Zirbs, Ronald; Reimhult, Erik

    2016-05-01

    Fundamental research on nanoparticle (NP) interactions and development of next-generation biomedical NP applications relies on synthesis of monodisperse, functional, core-shell nanoparticles free of residual dispersants with truly homogeneous and controlled physical properties. Still, synthesis and purification of e.g. such superparamagnetic iron oxide NPs remain a challenge. Comparing the success of different methods is marred by the sensitivity of analysis methods to the purity of the product. We synthesize monodisperse, oleic acid (OA)-capped, Fe3O4 NPs in the superparamagnetic size range (3-10 nm). Ligand exchange of OA for poly(ethylene glycol) (PEG) was performed with the PEG irreversibly grafted to the NP surface by a nitrodopamine (NDA) anchor. Four different methods were investigated to remove excess ligands and residual OA: membrane centrifugation, dialysis, size exclusion chromatography, and precipitation combined with magnetic decantation. Infrared spectroscopy and thermogravimetric analysis were used to determine the purity of samples after each purification step. Importantly, only magnetic decantation yielded pure NPs at high yields with sufficient grafting density for biomedical applications (∼1 NDA-PEG(5 kDa)/nm(2), irrespective of size). The purified NPs withstand challenging tests such as temperature cycling in serum and long-term storage in biological buffers. Dynamic light scattering, transmission electron microscopy, and small-angle X-ray scattering show stability over at least 4 months also in serum. The successful synthesis and purification route is compatible with any conceivable functionalization for biomedical or biomaterial applications of PEGylated Fe3O4 NPs. PMID:27046133

  11. Polyethylene Glycol-Mediated Synthesis of Cubic Iron Oxide Nanoparticles with High Heating Power

    NASA Astrophysics Data System (ADS)

    Iacovita, Cristian; Stiufiuc, Rares; Radu, Teodora; Florea, Adrian; Stiufiuc, Gabriela; Dutu, Alina; Mican, Sever; Tetean, Romulus; Lucaciu, Constantin M.

    2015-10-01

    Iron oxide magnetic nanoparticles (IOMNPs) have been successfully synthesized by means of solvothermal reduction method employing polyethylene glycol (PEG200) as a solvent. The as-synthesized IOMNPs are poly-dispersed, highly crystalline, and exhibit a cubic shape. The size of IOMNPs is strongly dependent on the reaction time and the ration between the amount of magnetic precursor and PEG200 used in the synthesis method. At low magnetic precursor/PEG200 ratio, the cubic IOMNPs coexist with polyhedral IOMNPs. The structure and morphology of the IOMNPs were thoroughly investigated by using a wide range of techniques: TEM, XRD, XPS, FTIR, and RAMAN. XPS analysis showed that the IOMNPs comprise a crystalline magnetite core bearing on the outer surface functional groups from PEG200 and acetate. The presence of physisorbed PEG200 on the IOMNP surface is faintly detected through FT-IR spectroscopy. The surface of IOMNPs undergoes oxidation into maghemite as proven by RAMAN spectroscopy and the occurrence of satellite peaks in the Fe2p XP spectra. The magnetic studies performed on powder show that the blocking temperature (TB) of IOMNPs is around 300 K displaying a coercive field in between 160 and 170 Oe. Below the TB, the field-cooled (FC) curves turn concave and describe a plateau indicating that strong magnetic dipole-dipole interactions are manifested in between IOMNPs. The specific absorption rate (SAR) values increase with decreasing nanoparticle concentrations for the IOMNPs dispersed in water. The SAR dependence on the applied magnetic field, studied up to magnetic field amplitude of 60 kA/m, presents a sigmoid shape with saturation values up to 1700 W/g. By dispersing the IOMNPs in PEG600 (liquid) and PEG1000 (solid), it was found that the SAR values decrease by 50 or 75 %, indicating that the Brownian friction within the solvent was the main contributor to the heating power of IOMNPs.

  12. High interfacial activity of polymers "grafted through" functionalized iron oxide nanoparticle clusters.

    PubMed

    Foster, Lynn M; Worthen, Andrew J; Foster, Edward L; Dong, Jiannan; Roach, Clarissa M; Metaxas, Athena E; Hardy, Clifford D; Larsen, Eric S; Bollinger, Jonathan A; Truskett, Thomas M; Bielawski, Christopher W; Johnston, Keith P

    2014-09-01

    The mechanism by which polymers, when grafted to inorganic nanoparticles, lower the interfacial tension at the oil-water interface is not well understood, despite the great interest in particle stabilized emulsions and foams. A simple and highly versatile free radical "grafting through" technique was used to bond high organic fractions (by weight) of poly(oligo(ethylene oxide) monomethyl ether methacrylate) onto iron oxide clusters, without the need for catalysts. In the resulting ∼1 μm hybrid particles, the inorganic cores and grafting architecture contribute to the high local concentration of grafted polymer chains to the dodecane/water interface to produce low interfacial tensions of only 0.003 w/v % (polymer and particle core). This "critical particle concentration" (CPC) for these hybrid inorganic/polymer amphiphilic particles to lower the interfacial tension by 36 mN/m was over 30-fold lower than the critical micelle concentration of the free polymer (without inorganic cores) to produce nearly the same interfacial tension. The low CPC is favored by the high adsorption energy (∼10(6) kBT) for the large ∼1 μm hybrid particles, the high local polymer concentration on the particles surfaces, and the ability of the deformable hybrid nanocluster cores as well as the polymer chains to conform to the interface. The nanocluster cores also increased the entanglement of the polymer chains in bulk DI water or synthetic seawater, producing a viscosity up to 35,000 cP at 0.01 s(-1), in contrast with only 600 cP for the free polymer. As a consequence of these interfacial and rheological properties, the hybrid particles stabilized oil-in-water emulsions at concentrations as low as 0.01 w/v %, with average drop sizes down to 30 μm. In contrast, the bulk viscosity was low for the free polymer, and it did not stabilize the emulsions. The ability to influence the interfacial activity and rheology of polymers upon grafting them to inorganic particles, including clusters

  13. High interfacial activity of polymers "grafted through" functionalized iron oxide nanoparticle clusters.

    PubMed

    Foster, Lynn M; Worthen, Andrew J; Foster, Edward L; Dong, Jiannan; Roach, Clarissa M; Metaxas, Athena E; Hardy, Clifford D; Larsen, Eric S; Bollinger, Jonathan A; Truskett, Thomas M; Bielawski, Christopher W; Johnston, Keith P

    2014-09-01

    The mechanism by which polymers, when grafted to inorganic nanoparticles, lower the interfacial tension at the oil-water interface is not well understood, despite the great interest in particle stabilized emulsions and foams. A simple and highly versatile free radical "grafting through" technique was used to bond high organic fractions (by weight) of poly(oligo(ethylene oxide) monomethyl ether methacrylate) onto iron oxide clusters, without the need for catalysts. In the resulting ∼1 μm hybrid particles, the inorganic cores and grafting architecture contribute to the high local concentration of grafted polymer chains to the dodecane/water interface to produce low interfacial tensions of only 0.003 w/v % (polymer and particle core). This "critical particle concentration" (CPC) for these hybrid inorganic/polymer amphiphilic particles to lower the interfacial tension by 36 mN/m was over 30-fold lower than the critical micelle concentration of the free polymer (without inorganic cores) to produce nearly the same interfacial tension. The low CPC is favored by the high adsorption energy (∼10(6) kBT) for the large ∼1 μm hybrid particles, the high local polymer concentration on the particles surfaces, and the ability of the deformable hybrid nanocluster cores as well as the polymer chains to conform to the interface. The nanocluster cores also increased the entanglement of the polymer chains in bulk DI water or synthetic seawater, producing a viscosity up to 35,000 cP at 0.01 s(-1), in contrast with only 600 cP for the free polymer. As a consequence of these interfacial and rheological properties, the hybrid particles stabilized oil-in-water emulsions at concentrations as low as 0.01 w/v %, with average drop sizes down to 30 μm. In contrast, the bulk viscosity was low for the free polymer, and it did not stabilize the emulsions. The ability to influence the interfacial activity and rheology of polymers upon grafting them to inorganic particles, including clusters

  14. Different storage conditions influence biocompatibility and physicochemical properties of iron oxide nanoparticles.

    PubMed

    Zaloga, Jan; Janko, Christina; Agarwal, Rohit; Nowak, Johannes; Müller, Robert; Boccaccini, Aldo R; Lee, Geoffrey; Odenbach, Stefan; Lyer, Stefan; Alexiou, Christoph

    2015-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) have attracted increasing attention in many biomedical fields. In magnetic drug targeting SPIONs are injected into a tumour supplying artery and accumulated inside the tumour with a magnet. The effectiveness of this therapy is thus dependent on magnetic properties, stability and biocompatibility of the particles. A good knowledge of the effect of storage conditions on those parameters is of utmost importance for the translation of the therapy concept into the clinic and for reproducibility in preclinical studies. Here, core shell SPIONs with a hybrid coating consisting of lauric acid and albumin were stored at different temperatures from 4 to 45 °C over twelve weeks and periodically tested for their physicochemical properties over time. Surprisingly, even at the highest storage temperature we did not observe denaturation of the protein or colloidal instability. However, the saturation magnetisation decreased by maximally 28.8% with clear correlation to time and storage temperature. Furthermore, the biocompatibility was clearly affected, as cellular uptake of the SPIONs into human T-lymphoma cells was crucially dependent on the storage conditions. Taken together, the results show that the particle properties undergo significant changes over time depending on the way they are stored.

  15. Different Storage Conditions Influence Biocompatibility and Physicochemical Properties of Iron Oxide Nanoparticles

    PubMed Central

    Zaloga, Jan; Janko, Christina; Agarwal, Rohit; Nowak, Johannes; Müller, Robert; Boccaccini, Aldo R.; Lee, Geoffrey; Odenbach, Stefan; Lyer, Stefan; Alexiou, Christoph

    2015-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) have attracted increasing attention in many biomedical fields. In magnetic drug targeting SPIONs are injected into a tumour supplying artery and accumulated inside the tumour with a magnet. The effectiveness of this therapy is thus dependent on magnetic properties, stability and biocompatibility of the particles. A good knowledge of the effect of storage conditions on those parameters is of utmost importance for the translation of the therapy concept into the clinic and for reproducibility in preclinical studies. Here, core shell SPIONs with a hybrid coating consisting of lauric acid and albumin were stored at different temperatures from 4 to 45 °C over twelve weeks and periodically tested for their physicochemical properties over time. Surprisingly, even at the highest storage temperature we did not observe denaturation of the protein or colloidal instability. However, the saturation magnetisation decreased by maximally 28.8% with clear correlation to time and storage temperature. Furthermore, the biocompatibility was clearly affected, as cellular uptake of the SPIONs into human T-lymphoma cells was crucially dependent on the storage conditions. Taken together, the results show that the particle properties undergo significant changes over time depending on the way they are stored. PMID:25918940

  16. Multifunctional Superparamagnetic Iron Oxide Nanoparticles for Combined Chemotherapy and Hyperthermia Cancer Treatment

    PubMed Central

    Quinto, Christopher A.; Mohindra, Priya; Tong, Sheng

    2015-01-01

    Superparamagnetic iron oxide nanoparticles (SPIOs) have the potential for use as a multimodal cancer therapy agent due to their ability to carry anticancer drugs and generate localized heat when exposed to an alternating magnetic field, resulting in combined chemotherapy and hyperthermia. To explore this potential, we synthesized SPIOs with a phospholipid-polyethylene glycol (PEG) coating, and loaded Doxorubicin (DOX) with 30.8% w/w loading capacity when the PEG length is optimized. We found that DOX-loaded SPIOs exhibited a sustained DOX release over 72 hours where the release kinetics could be altered by PEG length. In contrast, the heating efficiency of the SPIOs showed minimal change with PEG length. With a core size of 14 nm, the SPIOs could generate sufficient heat to raise the local temperature to 43°C, enough to trigger apoptosis in cancer cells. Further, we found that DOX-loaded SPIOs resulted in cell death comparable to free DOX, and that the combined effect of DOX and SPIO-induced hyperthermia enhanced cancer cell death in vitro. This study demonstrates the potential of using phospholipid-PEG coated SPIOs for chemotherapy-hyperthermia combinatorial cancer treatment with increased efficacy. PMID:26154916

  17. Facile and sustainable synthesis of shaped iron oxide nanoparticles: effect of iron precursor salts on the shapes of iron oxides.

    PubMed

    Sayed, Farheen N; Polshettiwar, Vivek

    2015-05-05

    A facile and sustainable protocol for synthesis of six different shaped iron oxides is developed. Notably, all the six shapes of iron oxides can be synthesised using exactly same synthetic protocol, by simply changing the precursor iron salts. Several of the synthesised shapes are not reported before. This novel protocol is relatively easy to implement and could contribute to overcome the challenge of obtaining various shaped iron oxides in economical and sustainable manner.

  18. Facile and Sustainable Synthesis of Shaped Iron Oxide Nanoparticles: Effect of Iron Precursor Salts on the Shapes of Iron Oxides

    PubMed Central

    Sayed, Farheen N.; Polshettiwar, Vivek

    2015-01-01

    A facile and sustainable protocol for synthesis of six different shaped iron oxides is developed. Notably, all the six shapes of iron oxides can be synthesised using exactly same synthetic protocol, by simply changing the precursor iron salts. Several of the synthesised shapes are not reported before. This novel protocol is relatively easy to implement and could contribute to overcome the challenge of obtaining various shaped iron oxides in economical and sustainable manner. PMID:25939969

  19. Remarkable efficiency of ultrafine superparamagnetic iron(III) oxide nanoparticles toward arsenate removal from aqueous environment.

    PubMed

    Kilianová, Martina; Prucek, Robert; Filip, Jan; Kolařík, Jan; Kvítek, Libor; Panáček, Aleš; Tuček, Jiří; Zbořil, Radek

    2013-11-01

    Arsenates, when present in water resources, constitute a risk to human health. In order to remove them, various technologies have been developed; out of them, sorption approach is widely adopted employing a wide spectrum of suitable sorbent materials. Nanoparticles of iron oxide are frequently used due to a high surface area and ability to control them by external magnetic field. In this work, we report on a simple and cheap synthesis of ultrafine iron(III) oxide nanoparticles with a narrow size distribution and their exploitation in the field of arsenate removal from aqueous environment. It is shown that the adsorption capacity is enhanced by a mesoporous nature of nanoparticle arrangement in their system due to strong magnetic interactions they evolve between nanoparticles. A complete arsenate removal is achieved at Fe/As ratio equal to ∼20/1 and at pH in the range from 5 to 7.6. Under these conditions, the arsenates are completely removed within several minutes of treatment. Among iron-oxide-based nanosystems synthesized and employed in arsenate remediation issues so far, our assembly of iron(III) oxide nanoparticles shows the highest Freundlich adsorption coefficient and equilibrium sorption capacity under conditions maintained. Taking into account simple and low-cost preparation procedure, product high yields, almost monodispersed character, room-temperature superparamagnetic behavior, and strong magnetic response under small applied magnetic fields, the synthesized iron(III) oxide nanoparticles can be regarded as a promising candidate for exploitation in the field of removing undesired toxic pollutants from various real water systems.

  20. Generation of drugs coated iron nanoparticles through high energy ball milling

    NASA Astrophysics Data System (ADS)

    Radhika Devi, A.; Chelvane, J. A.; Prabhakar, P. K.; Padma Priya, P. V.; Doble, Mukesh; Murty, B. S.

    2014-03-01

    The iron nanoparticles coated with oleic acid and drugs such as folic acid/Amoxicillin were synthesized by high energy ball milling and characterized by X-ray diffraction, Transmission electron microscope, zeta potential, dynamic light scattering, Fourier Transform Infra red (FT-IR) measurements, and thermo gravimetric analysis (TGA). FT-IR and TGA measurements show good adsorption of drugs on oleic acid coated nanoparticles. Magnetic measurements indicate that saturation magnetization is larger for amoxicillin coated particles compared to folic acid coated particles. The biocompatibility of the magnetic nanoparticles prepared was evaluated by in vitro cytotoxicity assay using L929 cells as model cells.

  1. Generation of drugs coated iron nanoparticles through high energy ball milling

    SciTech Connect

    Radhika Devi, A.; Murty, B. S.; Chelvane, J. A.; Prabhakar, P. K.; Padma Priya, P. V.; Doble, Mukesh

    2014-03-28

    The iron nanoparticles coated with oleic acid and drugs such as folic acid/Amoxicillin were synthesized by high energy ball milling and characterized by X-ray diffraction, Transmission electron microscope, zeta potential, dynamic light scattering, Fourier Transform Infra red (FT-IR) measurements, and thermo gravimetric analysis (TGA). FT-IR and TGA measurements show good adsorption of drugs on oleic acid coated nanoparticles. Magnetic measurements indicate that saturation magnetization is larger for amoxicillin coated particles compared to folic acid coated particles. The biocompatibility of the magnetic nanoparticles prepared was evaluated by in vitro cytotoxicity assay using L929 cells as model cells.

  2. Silica-coated super paramagnetic iron oxide nanoparticles (SPION) as biocompatible contrast agent in biomedical photoacoustics

    PubMed Central

    Alwi, Rudolf; Telenkov, Sergey; Mandelis, Andreas; Leshuk, Timothy; Gu, Frank; Oladepo, Sulayman; Michaelian, Kirk

    2012-01-01

    In this study, we report for the first time the use of silica-coated superparamagnetic iron oxide nanoparticles (SPION) as contrast agents in biomedical photoacoustic imaging. Using frequency-domain photoacoustic correlation (the photoacoustic radar), we investigated the effects of nanoparticle size, concentration and biological media (e.g. serum, sheep blood) on the photoacoustic response in turbid media. Maximum detection depth and the minimum measurable SPION concentration were determined experimentally. The nanoparticle-induced optical contrast ex vivo in dense muscular tissues (avian pectus and murine quadricept) was evaluated and the strong potential of silica-coated SPION as a possible photoacoustic contrast agents was demonstrated. PMID:23082291

  3. Recent advances in synthesis and surface modification of superparamagnetic iron oxide nanoparticles with silica

    NASA Astrophysics Data System (ADS)

    Sodipo, Bashiru Kayode; Aziz, Azlan Abdul

    2016-10-01

    Research on synthesis of superparamagnetic iron oxide nanoparticles (SPION) and its surface modification for biomedical applications is of intense interest. Due to superparamagnetic property of SPION, the nanoparticles have large magnetic susceptibility, single magnetic domain and controllable magnetic behaviour. However, owing to easy agglomeration of SPION, surface modification of the magnetic particles with biocompatible materials such as silica nanoparticle has gained much attention in the last decade. In this review, we present recent advances in synthesis of SPION and various routes of producing silica coated SPION.

  4. Synthesis and magnetic study of carbon coated iron oxide nanoparticles by laser ablation in solution

    NASA Astrophysics Data System (ADS)

    Prajapat, C. L.; Sharma, P.; Gonal, M. R.; Vatsa, R. K.; Singh, M. R.; Ravikumar, G.

    2016-05-01

    Magnetic Iron oxides nanoparticles (NPs) were prepared by Laser Ablation in Solution method. Formation and average size of iron oxide NPs (~8 nm) is confirmed by XRD pattern and magnetization studies. Detailed magnetic studies have been carried out using SQUID magnetometer. The saturation magnetization for the iron oxide NPs was found to be 60.07 emu/g. Below the blocking temperature of 150 K the hysteresis loop shows ferromagnetic nature, whereas it shows superparamagnetic behavior at 300 K, for the synthesized NPs.

  5. Antiferromagnetic coupling in ferrimagnetic hard-soft core/shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Nogues, Josep

    2015-03-01

    The coupling between different magnetic layers in thin film bi-layers and multilayer systems is usually ferromagnetic (FM) (layers parallel to each other). However, other types of couplings such as antiferromagnetic (AFM) (i.e., antiparallel layers) have also been reported. In contrast, the magnetic properties of bi-magnetic core/shell nanoparticles remain relatively unexplored. While Monte Carlo simulations have probed the effects of different types of interface couplings from the theoretical point of view (e.g., FM vs. AFM coupling), experimental work so far has only reported ferromagnetic coupling between the counterparts. Here we present the existence of an interfacial AFM coupling in ferrimagnetic (FiM) soft/hard and hard/soft core/shell nanoparticles based on iron and manganese oxides. Narrow size distributed Fe3O4/Mn3O4andMn3O4/Fe3O4 core/shell, soft/hard and hard/soft, were synthesized by seeded growth. In contrast to conventional systems, the temperature dependence of the magnetization, M, and the ferromagnetic resonance field, HR, show a downturn at the magnetic ordering temperature of the hard Mn3O4phase(TC(Mn3O4) = 40 K). This decrease in M and HR can be linked to an antiferromagnetic coupling between both phases. Moreover, element selective X-ray magnetic circular dichroism (XMCD) spectra and hysteresis loops confirm that the magnetization of the Mn-containing phase lies opposite to the Fe-containing phase. Magnetometry hysteresis loops show that for small cooling fields the loop shifts towards negative fields similar to exchange bias in conventional FM/AFM systems. However, for large cooling fields the loops shift to the opposite direction, i.e., positive exchange bias. Finally, Monte Carlo simulations clearly confirm that an AFM interface coupling leads to a magnetization decrease at low temperatures and a positive exchange bias for large cooling fields. Partial support from the MAT2013-48628-R project.

  6. Chromenone-conjugated magnetic iron oxide nanoparticles. Toward conveyable DNA binders.

    PubMed

    Yousuf, Sameena; Enoch, Israel V M V; Paulraj, Mosae Selvalumar; Dhanaraj, Premnath

    2015-11-01

    Magnetic nanoparticles can transport drug and possibly target cancer. DNA-binding of ligands loaded in dextran coated magnetic nanoparticles, could aid their better target-specific binding. In this work, we report the loading of chromenones onto aminoethylamino-modified dextran coated iron oxide nanoparticles, their loading efficiency, and openness for binding to DNA. The magnetic behavior, the size, and the morphology of the nanoparticles are analyzed. The crystallite size of the magnetic nanoparticles is around 40 nm. The chromenones are present on the surface of the dextran shell, as revealed by their cyclodextrin-binding characteristics, which is a new approach in comprehending the accessibility of the surface-bound molecules by macromolecules. The mode of binding of the chromenones to DNA is not altered on surface loading on dextran shell, although the binding strength is generally diminished, compared to the strength of binding of the free chromenones to DNA.

  7. A New Class of Silica Crosslinked Micellar Core-Shell /nanoparticles."

    SciTech Connect

    Huo, Qisheng; Liu, Jun; Wang, Li Q.; Jiang, Yingbing; Lambert, Timothy N.; Fang, Erica

    2006-05-17

    Micellar nanoparticles made of surfactants and polymers have attracted wide attention in the materials and biomedical community for controlled drug delivery, molecular imaging and sensing; however, their long-term stability remains a topic of intense study. Here we report a new class of robust, ultrafine (10nm) silica core-shell nanoparticles formed from silica crosslinked, individual block copolymer micelles. Compared with pure polymer micelles, the new core-shell nanoparticles have significantly improved stability and do not break down during dilution. They also achieve much higher loading capacity for a wide range of chemicals, with the entrapped molecules slowly released over a much longer period of time. A wide range of functional groups can be easily incorporated through co-condensation with the silica matrix. The potential to deliver hydrophobic agents into cancer cells has been demonstrated. Because of their unique properties, these novel core-shell nanoparticles could potentially provide a new nanomedicine platform for imaging, detection and treatment.

  8. Comparative toxicity of silicon dioxide, silver and iron oxide nanoparticles after repeated oral administration to rats.

    PubMed

    Yun, Jun-Won; Kim, Seung-Hyun; You, Ji-Ran; Kim, Woo Ho; Jang, Ja-June; Min, Seung-Kee; Kim, Hee Chan; Chung, Doo Hyun; Jeong, Jayoung; Kang, Byeong-Cheol; Che, Jeong-Hwan

    2015-06-01

    Although silicon dioxide (SiO2), silver (Ag) and iron oxide (Fe2O3) nanoparticles are widely used in diverse applications from food to biomedicine, in vivo toxicities of these nanoparticles exposed via the oral route remain highly controversial. To examine the systemic toxicity of these nanoparticles, well-dispersed nanoparticles were orally administered to Sprague-Dawley rats daily over a 13-week period. Based on the results of an acute toxicity and a 14-day repeated toxicity study, 975.9, 1030.5 and 1000 mg kg(-1) were selected as the highest dose of the SiO2 , Ag and Fe2O3 nanoparticles, respectively, for the 13-week repeated oral toxicity study. The SiO2 and Fe2O3 nanoparticles did not induce dose-related changes in a number of parameters associated with the systemic toxicity up to 975.9 and 1000 mg kg(-1) , respectively, whereas the Ag nanoparticles resulted in increases in serum alkaline phosphatase and calcium as well as lymphocyte infiltration in liver and kidney, raising the possibility of liver and kidney toxicity induced by the Ag nanoparticles. Compared with the SiO2 and Fe2O3 nanoparticles showing no systemic distribution in all tissues tested, the Ag concentration in sampled blood and organs in the Ag nanoparticle-treated group significantly increased with a positive and/or dose-related trend, meaning that the systemic toxicity of the Ag nanoparticles, including liver and kidney toxicity, might be explained by extensive systemic distribution of Ag originating from the Ag nanoparticles. Our current results suggest that further study is required to identify that Ag detected outside the gastrointestinal tract were indeed a nanoparticle form or ionized form.

  9. Direct measurement of thermal conductivity in solid iron at planetary core conditions.

    PubMed

    Konôpková, Zuzana; McWilliams, R Stewart; Gómez-Pérez, Natalia; Goncharov, Alexander F

    2016-06-01

    The conduction of heat through minerals and melts at extreme pressures and temperatures is of central importance to the evolution and dynamics of planets. In the cooling Earth's core, the thermal conductivity of iron alloys defines the adiabatic heat flux and therefore the thermal and compositional energy available to support the production of Earth's magnetic field via dynamo action. Attempts to describe thermal transport in Earth's core have been problematic, with predictions of high thermal conductivity at odds with traditional geophysical models and direct evidence for a primordial magnetic field in the rock record. Measurements of core heat transport are needed to resolve this difference. Here we present direct measurements of the thermal conductivity of solid iron at pressure and temperature conditions relevant to the cores of Mercury-sized to Earth-sized planets, using a dynamically laser-heated diamond-anvil cell. Our measurements place the thermal conductivity of Earth's core near the low end of previous estimates, at 18-44 watts per metre per kelvin. The result is in agreement with palaeomagnetic measurements indicating that Earth's geodynamo has persisted since the beginning of Earth's history, and allows for a solid inner core as old as the dynamo. PMID:27251283

  10. Direct measurement of thermal conductivity in solid iron at planetary core conditions

    NASA Astrophysics Data System (ADS)

    Konôpková, Zuzana; McWilliams, R. Stewart; Gómez-Pérez, Natalia; Goncharov, Alexander F.

    2016-06-01

    The conduction of heat through minerals and melts at extreme pressures and temperatures is of central importance to the evolution and dynamics of planets. In the cooling Earth’s core, the thermal conductivity of iron alloys defines the adiabatic heat flux and therefore the thermal and compositional energy available to support the production of Earth’s magnetic field via dynamo action. Attempts to describe thermal transport in Earth’s core have been problematic, with predictions of high thermal conductivity at odds with traditional geophysical models and direct evidence for a primordial magnetic field in the rock record. Measurements of core heat transport are needed to resolve this difference. Here we present direct measurements of the thermal conductivity of solid iron at pressure and temperature conditions relevant to the cores of Mercury-sized to Earth-sized planets, using a dynamically laser-heated diamond-anvil cell. Our measurements place the thermal conductivity of Earth’s core near the low end of previous estimates, at 18-44 watts per metre per kelvin. The result is in agreement with palaeomagnetic measurements indicating that Earth’s geodynamo has persisted since the beginning of Earth’s history, and allows for a solid inner core as old as the dynamo.

  11. Direct measurement of thermal conductivity in solid iron at planetary core conditions

    NASA Astrophysics Data System (ADS)

    Konôpková, Zuzana; McWilliams, R. Stewart; Gómez-Pérez, Natalia; Goncharov, Alexander F.

    2016-06-01

    The conduction of heat through minerals and melts at extreme pressures and temperatures is of central importance to the evolution and dynamics of planets. In the cooling Earth’s core, the thermal conductivity of iron alloys defines the adiabatic heat flux and therefore the thermal and compositional energy available to support the production of Earth’s magnetic field via dynamo action. Attempts to describe thermal transport in Earth’s core have been problematic, with predictions of high thermal conductivity at odds with traditional geophysical models and direct evidence for a primordial magnetic field in the rock record. Measurements of core heat transport are needed to resolve this difference. Here we present direct measurements of the thermal conductivity of solid iron at pressure and temperature conditions relevant to the cores of Mercury-sized to Earth-sized planets, using a dynamically laser-heated diamond-anvil cell. Our measurements place the thermal conductivity of Earth’s core near the low end of previous estimates, at 18–44 watts per metre per kelvin. The result is in agreement with palaeomagnetic measurements indicating that Earth’s geodynamo has persisted since the beginning of Earth’s history, and allows for a solid inner core as old as the dynamo.

  12. Direct measurement of thermal conductivity in solid iron at planetary core conditions.

    PubMed

    Konôpková, Zuzana; McWilliams, R Stewart; Gómez-Pérez, Natalia; Goncharov, Alexander F

    2016-06-01

    The conduction of heat through minerals and melts at extreme pressures and temperatures is of central importance to the evolution and dynamics of planets. In the cooling Earth's core, the thermal conductivity of iron alloys defines the adiabatic heat flux and therefore the thermal and compositional energy available to support the production of Earth's magnetic field via dynamo action. Attempts to describe thermal transport in Earth's core have been problematic, with predictions of high thermal conductivity at odds with traditional geophysical models and direct evidence for a primordial magnetic field in the rock record. Measurements of core heat transport are needed to resolve this difference. Here we present direct measurements of the thermal conductivity of solid iron at pressure and temperature conditions relevant to the cores of Mercury-sized to Earth-sized planets, using a dynamically laser-heated diamond-anvil cell. Our measurements place the thermal conductivity of Earth's core near the low end of previous estimates, at 18-44 watts per metre per kelvin. The result is in agreement with palaeomagnetic measurements indicating that Earth's geodynamo has persisted since the beginning of Earth's history, and allows for a solid inner core as old as the dynamo.

  13. Ab initio melting curve of iron at extreme pressures: implications for exoplanets' cores

    NASA Astrophysics Data System (ADS)

    Bouchet, J.; Morard, G.; Valencia, D. C.; Mazevet, S.; Guyot, F. J.

    2010-12-01

    Exoplanets with masses similar to that of Earth have recently been discovered1. A first order question for understanding their dynamics is to know whether they possess Earth like liquid metallic cores. However, the iron melting curve is unknown at conditions corresponding to planets of several times the Earth's mass (over 15 Mbar for planets with 10 times the Earth’s mass (ME)2). In the density-temperature region of the cores of those super-Earths, we calculate the iron melting curve using first principle molecular dynamics simulations based on density functional theory. By comparing calculated thermal profiles of Super Earths, we show that planets heavier than 3-5 ME have solid cores, thus precluding the existence of an internal magnetic field. This new field of investigation of the iron melting curve shows that the Earth may be close to the maximal size for a terrestrial planet to possess a partially molten metallic core. References 1 J. P. Beaulieu, D. P. Bennett, P. Fouque et al., Nature 439 (7075), 437 (2006). 2 D. Valencia, R. J. O'Connell, and D. Sasselov, Icarus 181, 545 (2006).

  14. Magnetic nanoparticles formed in glasses co-doped with iron and larger radius elements

    SciTech Connect

    Edelman, I.; Ivanova, O.; Ivantsov, R.; Velikanov, D.; Zabluda, V.; Zubavichus, Y.; Veligzhanin, A.; Zaikovskiy, V.; Stepanov, S.; Artemenko, A.; Curely, J.; Kliava, J.

    2012-10-15

    A new type of nanoparticle-containing glasses based on borate glasses co-doped with low contents of iron and larger radius elements, Dy, Tb, Gd, Ho, Er, Y, and Bi, is studied. Heat treatment of these glasses results in formation of magnetic nanoparticles, radically changing their physical properties. Transmission electron microscopy and synchrotron radiation-based techniques: x-ray diffraction, extended x-ray absorption fine structure, x-ray absorption near-edge structure, and small-angle x-ray scattering, show a broad distribution of nanoparticle sizes with characteristics depending on the treatment regime; a crystalline structure of these nanoparticles is detected in heat treated samples. Magnetic circular dichroism (MCD) studies of samples subjected to heat treatment as well as of maghemite, magnetite, and iron garnet allow to unambiguously assign the nanoparticle structure to maghemite, independently of co-dopant nature and of heat treatment regime used. Different features observed in the MCD spectra are related to different electron transitions in Fe{sup 3+} ions gathered in the nanoparticles. The static magnetization in heat treated samples has non-linear dependence on the magnetizing field with hysteresis. Zero-field cooled magnetization curves show that at higher temperatures the nanoparticles occur in superparamagnetic state with blocking temperatures above 100 K. Below ca. 20 K, a considerable contribution to both zero field-cooled and field-cooled magnetizations occurs from diluted paramagnetic ions. Variable-temperature electron magnetic resonance (EMR) studies unambiguously show that in as-prepared glasses paramagnetic ions are in diluted state and confirm the formation of magnetic nanoparticles already at earlier stages of heat treatment. Computer simulations of the EMR spectra corroborate the broad distribution of nanoparticle sizes found by 'direct' techniques as well as superparamagnetic nanoparticle behaviour demonstrated in the magnetization

  15. Magnetic nanoparticles formed in glasses co-doped with iron and larger radius elements

    NASA Astrophysics Data System (ADS)

    Edelman, I.; Ivanova, O.; Ivantsov, R.; Velikanov, D.; Zabluda, V.; Zubavichus, Y.; Veligzhanin, A.; Zaikovskiy, V.; Stepanov, S.; Artemenko, A.; Curély, J.; Kliava, J.

    2012-10-01

    A new type of nanoparticle-containing glasses based on borate glasses co-doped with low contents of iron and larger radius elements, Dy, Tb, Gd, Ho, Er, Y, and Bi, is studied. Heat treatment of these glasses results in formation of magnetic nanoparticles, radically changing their physical properties. Transmission electron microscopy and synchrotron radiation-based techniques: x-ray diffraction, extended x-ray absorption fine structure, x-ray absorption near-edge structure, and small-angle x-ray scattering, show a broad distribution of nanoparticle sizes with characteristics depending on the treatment regime; a crystalline structure of these nanoparticles is detected in heat treated samples. Magnetic circular dichroism (MCD) studies of samples subjected to heat treatment as well as of maghemite, magnetite, and iron garnet allow to unambiguously assign the nanoparticle structure to maghemite, independently of co-dopant nature and of heat treatment regime used. Different features observed in the MCD spectra are related to different electron transitions in Fe3+ ions gathered in the nanoparticles. The static magnetization in heat treated samples has non-linear dependence on the magnetizing field with hysteresis. Zero-field cooled magnetization curves show that at higher temperatures the nanoparticles occur in superparamagnetic state with blocking temperatures above 100 K. Below ca. 20 K, a considerable contribution to both zero field-cooled and field-cooled magnetizations occurs from diluted paramagnetic ions. Variable-temperature electron magnetic resonance (EMR) studies unambiguously show that in as-prepared glasses paramagnetic ions are in diluted state and confirm the formation of magnetic nanoparticles already at earlier stages of heat treatment. Computer simulations of the EMR spectra corroborate the broad distribution of nanoparticle sizes found by "direct" techniques as well as superparamagnetic nanoparticle behaviour demonstrated in the magnetization studies.

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

    NASA Astrophysics Data System (ADS)

    Smolkova, Ilona S.; Kazantseva, Natalia E.; Babayan, Vladimir; Smolka, Petr; Parmar, Harshida; Vilcakova, Jarmila; Schneeweiss, Oldrich; Pizurova, Nadezda

    2015-01-01

    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-1 to 48 emu g-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-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.

  17. Whole Body Retention and Distribution of Orally-Adminsitered Radiolabeled Zerovalent Iron nanoparticles in Mice

    EPA Science Inventory

    Zerovalent iron nanoparticles (nZVI) are used for in situ remediation of contaminated ground water, raising the possibility that nZVI particles or their altered residues could contaminate the ground water. Therefore, it is important to study their effects on humans and other orga...

  18. VAPOR PHASE MERCURY SORPTION BY ORGANIC SULFIDE MODIFIED BIMETALLIC IRON-COPPER NANOPARTICLE AGGREGATES

    EPA Science Inventory

    Novel organic sulfide modified bimetallic iron-copper nanoparticle aggregate sorbent materials have been synthesized for removing elemental mercury from vapor streams at elevated temperatures (120-140 °C). Silane based (disulfide silane and tetrasulfide silane) and alkyl sulfide ...

  19. Ordered Mesoporous Carbon/Iron Oxide Nanoparticle Composites for Supercapacitor Applications

    NASA Astrophysics Data System (ADS)

    Lin, Ying; Wang, Xinyu; Watkins, James

    2013-03-01

    Novel mesoporous carbon/iron oxide composites were prepared through a simple carbonization procedure of blends of block copolymer precursors containing the source of carbon, i.e., polyacrylonitrile-block-poly(t-butyl acrylate) (PtBA-b-PAN) with iron oxide nanoparticles. The addition of functionalized nanoparticles that selectively hydrogen bond with PAN segments was shown to induce order in otherwise disordered system. The ordered mesostructure of the composites was confirmed by both small x-ray scattering and transmission electron microscopy. The preparation of nanocomposites with pore structure was enabled by the high ?delity preservation of the phase-separated nanostructure between two polymer blocks driven by nanoparticle additive upon carbonization at 700oC. The electrochemical performance of the composite films was compared to that of the neat carbon and the mesoporous carbon without iron oxide nanoparticles. The mesoporous structure together with the high iron contents in such materials make them particularly promising for use in supercapacitor applications. This work was supported by the NSF Center for Hierarchical Manufacturing at the University of Massachusetts (CMMI-0531171).

  20. Iron(II,III)-polyphenol complex nanoparticles derived from green tea with remarkable ecotoxicological impact

    EPA Science Inventory

    There are several greener methods exist to synthesize zero–valent iron nanoparticles (nZVI) using different bio-based reducing agents. Although their useful properties in degradation of organic dyes, chlorinated organics, or arsenic have been described earlier, their characteriza...

  1. Synthesis and properties MFe2O4 (M = Fe, Co) nanoparticles and core-shell structures

    NASA Astrophysics Data System (ADS)

    Yelenich, O. V.; Solopan, S. O.; Greneche, J. M.; Belous, A. G.

    2015-08-01

    Individual Fe3-xO4 and CoFe2O4 nanoparticles, as well as Fe3-xO4/CoFe2O4 core/shell structures were synthesized by the method of co-precipitation from diethylene glycol solutions. Core/shell structure were synthesized with CoFe2O4-shell thickness of 1.0, 2.5 and 3.5 nm. X-ray diffraction patterns of individual nanoparticles and core/shell are similar and indicate that all synthesized samples have a cubic spinel structure. Compares Mössbauer studies of CoFe2O4, Fe3-xO4 nanoparticles indicate superparamagnetic properties at 300 K. It was shown that individual magnetite nanoparticles are transformed into maghemite through oxidation during the synthesis procedure, wherein the smallest nanoparticles are completely oxidized while a magnetite core does occur in the case of the largest nanoparticles. The Mössbauer spectra of core/shell nanoparticles with increasing CoFe2O4-shell thickness show a gradual decrease in the relative intensity of the quadrupole doublet and significant decrease of the mean isomer shift value at both RT and 77 K indicating a decrease of the superparamagnetic relaxation phenomena. Specific loss power for the prepared ferrofluids was experimentally calculated and it was determined that under influence of ac-magnetic field magnetic fluid based on individual CoFe2O4 and Fe3-xO4 particles are characterized by very low heating temperature, when magnetic fluids based on core/shell nanoparticles demonstrate higher heating effect.

  2. Stellar Iron Core Collapse in 3+1 General Relativity and The Gravitational Wave Signature of Core-Collapse Supernovae.

    NASA Astrophysics Data System (ADS)

    Ott, Christian David

    2007-04-01

    I perform and analyze the first ever calculations of rotating stellar iron core collapse in {3+1} general relativity that start out with presupernova models from stellar evolutionary calculations and include a microphysical finite-temperature nuclear equation of state, an approximate scheme for electron capture during collapse and neutrino pressure effects. Based on the results of these calculations, I obtain the to-date most realistic estimates for the gravitational wave signal from collapse, bounce and the early postbounce phase of core collapse supernovae. I supplement my {3+1} GR hydrodynamic simulations with 2D Newtonian neutrino radiation-hydrodynamic supernova calculations focussing on (1) the late postbounce gravitational wave emission owing to convective overturn, anisotropic neutrino emission and protoneutron star pulsations, and (2) on the gravitational wave signature of accretion-induced collapse of white dwarfs to neutron stars.

  3. Platinum Monolayer on IrFe Core-Shell Nanoparticle Electrocatalysts for the Oxygen Reduction Reaction

    SciTech Connect

    K Sasaki; K Kuttiyiel; D Su; R Adzic

    2011-12-31

    We synthesized high activity and stability platinum monolayer on IrFe core-shell nanoparticle electrocatalysts. Carbon-supported IrFe core-shell nanoparticles were synthesized by chemical reduction and subsequent thermal annealing. The formation of Ir shells on IrFe solid-solution alloy cores has been verified by scanning transmission electron microscopy coupled with energy-loss spectroscopy (EELS) and in situ X-ray absorption spectroscopy. The Pt monolayers were deposited on IrFe core-shell nanoparticles by galvanic replacement of underpotentially deposited Cu adatoms on the Ir shell surfaces. The specific and Pt mass activities for the ORR on the Pt monolayer on IrFe core-shell nanoparticle electrocatalyst are 0.46 mA/cm{sup 2} and 1.1 A/mg{sub Pt}, which are much higher than those on a commercial Pt/C electrocatalyst. High durability of Pt{sub ML}/IrFe/C has also been demonstrated by potential cycling tests. These high activity and durability observed can be ascribed to the structural and electronic interaction between the Pt monolayer and the IrFe core-shell nanoparticles.

  4. Efficient internalization of silica-coated iron oxide nanoparticles of different sizes by primary human macrophages and dendritic cells

    SciTech Connect

    Kunzmann, Andrea; Andersson, Britta; Vogt, Carmen; Feliu, Neus; Ye Fei; Gabrielsson, Susanne; Toprak, Muhammet S.; Buerki-Thurnherr, Tina; Laurent, Sophie; Vahter, Marie; Krug, Harald; Muhammed, Mamoun; Scheynius, Annika; Fadeel, Bengt

    2011-06-01

    Engineered nanoparticles are being considered for a wide range of biomedical applications, from magnetic resonance imaging to 'smart' drug delivery systems. The development of novel nanomaterials for biomedical applications must be accompanied by careful scrutiny of their biocompatibility. In this regard, particular attention should be paid to the possible interactions between nanoparticles and cells of the immune system, our primary defense system against foreign invasion. On the other hand, labeling of immune cells serves as an ideal tool for visualization, diagnosis or treatment of inflammatory processes, which requires the efficient internalization of the nanoparticles into the cells of interest. Here, we compare novel monodispersed silica-coated iron oxide nanoparticles with commercially available dextran-coated iron oxide nanoparticles. The silica-coated iron oxide nanoparticles displayed excellent magnetic properties. Furthermore, they were non-toxic to primary human monocyte-derived macrophages at all doses tested whereas dose-dependent toxicity of the smaller silica-coated nanoparticles (30 nm and 50 nm) was observed for primary monocyte-derived dendritic cells, but not for the similarly small dextran-coated iron oxide nanoparticles. No macrophage or dendritic cell secretion of pro-inflammatory cytokines was observed upon administration of nanoparticles. The silica-coated iron oxide nanoparticles were taken up to a significantly higher degree when compared to the dextran-coated nanoparticles, irrespective of size. Cellular internalization of the silica-coated nanoparticles was through an active, actin cytoskeleton-dependent process. We conclude that these novel silica-coated iron oxide nanoparticles are promising materials for medical imaging, cell tracking and other biomedical applications.

  5. Magnetic Properties of Polyvinyl Alcohol and Doxorubicine Loaded Iron Oxide Nanoparticles for Anticancer Drug Delivery Applications

    PubMed Central

    Nadeem, Muhammad; Ahmad, Munir; Akhtar, Muhammad Saeed; Shaari, Amiruddin; Riaz, Saira; Naseem, Shahzad; Masood, Misbah; Saeed, M. A.

    2016-01-01

    The current study emphasizes the synthesis of iron oxide nanoparticles (IONPs) and impact of hydrophilic polymer polyvinyl alcohol (PVA) coating concentration as well as anticancer drug doxorubicin (DOX) loading on saturation magnetization for target drug delivery applications. Iron oxide nanoparticles particles were synthesized by a reformed version of the co-precipitation method. The coating of polyvinyl alcohol along with doxorubicin loading was carried out by the physical immobilization method. X-ray diffraction confirmed the magnetite (Fe3O4) structure of particles that remained unchanged before and after polyvinyl alcohol coating and drug loading. Microstructure and morphological analysis was carried out by transmission electron microscopy revealing the formation of nanoparticles with an average size of 10 nm with slight variation after coating and drug loading. Transmission electron microscopy, energy dispersive, and Fourier transform infrared spectra further confirmed the conjugation of polymer and doxorubicin with iron oxide nanoparticles. The room temperature superparamagnetic behavior of polymer-coated and drug-loaded magnetite nanoparticles were studied by vibrating sample magnetometer. The variation in saturation magnetization after coating evaluated that a sufficient amount of polyvinyl alcohol would be 3 wt. % regarding the externally controlled movement of IONPs in blood under the influence of applied magnetic field for in-vivo target drug delivery. PMID:27348436

  6. Use of triethylene glycol monobutyl ether in synthesis of iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Beyaz, Seda; Ozel, Fatmahan; Kockar, Hakan; Tanrisever, Taner

    2014-06-01

    Superparamagnetic iron oxide nanoparticles were synthesized by thermal decomposition of iron-oleate complex using triethylene glycol monobutyl ether (TREGBE) as solvent for the first time for more mass of the nanoparticles. The effect of TREGBE on the properties of the nanoparticles was compared with that of 1-hexadecene. The impact of oleic acid concentration on the properties of the nanoparticles was also studied. On the use of TREGBE as compared with 1-hexadecene, the average crystal size reduced from 9.1±2.1 to 8.2±0.7 nm whereas the saturation magnetization (Ms) increased from 53.6 to 58.0 emu/g. Moreover, more products can be synthesized using TREGBE. Besides, the interactions between particle surfaces and TREGBE are weaker than that of 1-hexadecene according to gravimetric analysis results. X-ray diffraction analysis revealed that crystallinity and particle size scaled up with increasing oleic acid amount in TREGBE. The electron microscopy showed that dot-shaped particles turned into irregular particles with increasing amount of oleic acid molecules using TREGBE. The results disclosed that TREGBE is quite a suitable solvent to synthesize the superparamagnetic iron oxide nanoparticles with the desired size and Ms for more mass production at low temperature.

  7. Reactive adsorption of SO2 on activated carbons with deposited iron nanoparticles.

    PubMed

    Arcibar-Orozco, Javier A; Rangel-Mendez, J Rene; Bandosz, Teresa J

    2013-02-15

    The effect of iron particle size anchored on the surface of commercial activated carbon on the removal of SO(2) from a gas phase was studied. Nanosize iron particles were deposited using forced hydrolysis of FeCl(3) with or without H(3)PO(4) as a capping agent. Dynamic adsorption experiments were carried out on either dry or pre-humidified materials and the adsorption capacities were calculated. The surface of the initial and exhausted materials was extensively characterized by microscopic, porosity, thermogravimetric and surface chemistry. The results indicate that the SO(2) adsorption capacity increased two and half times after the prehumidification process owing to the formation of H(2)SO(4) in the porous system. Iron species enhance the SO(2) adsorption capacity only when very small nanoparticles are deposited on the pore walls as a thin layer. Large iron nanoparticles block the ultramicropores decreasing the accessibility of the active sites and consuming oxygen that rest adsorption centers for SO(2) molecules. Iron nanoparticles of about 3-4 nm provide highly dispersed adsorption sites for SO(2) molecules and thus increase the adsorption capacity of about 80%. Fe(2)(SO(4))(3) was detected on the surface of exhausted samples. PMID:23333487

  8. Core-shell Au@Pd nanoparticles with enhanced catalytic activity for oxygen reduction reaction via core-shell Au@Ag/Pd constructions

    PubMed Central

    Chen, Dong; Li, Chengyin; Liu, Hui; Ye, Feng; Yang, Jun

    2015-01-01

    Core-shell nanoparticles often exhibit improved catalytic properties due to the lattice strain created in these core-shell particles. Herein, we demonstrate the synthesis of core-shell Au@Pd nanoparticles from their core-shell Au@Ag/Pd parents. This strategy begins with the preparation of core-shell Au@Ag nanoparticles in an organic solvent. Then, the pure Ag shells are converted into the shells made of Ag/Pd alloy by galvanic replacement reaction between the Ag shells and Pd2+ precursors. Subsequently, the Ag component is removed from the alloy shell using saturated NaCl solution to form core-shell Au@Pd nanoparticles with an Au core and a Pd shell. In comparison with the core-shell Au@Pd nanoparticles upon directly depositing Pd shell on the Au seeds and commercial Pd/C catalysts, the core-shell Au@Pd nanoparticles via their core-shell Au@Ag/Pd templates display superior activity and durability in catalyzing oxygen reduction reaction, mainly due to the larger lattice tensile effect in Pd shell induced by the Au core and Ag removal. PMID:26144550

  9. Core-shell nano-architectures: the incorporation mechanism of hydrophobic nanoparticles into the aqueous core of a microemulsion.

    PubMed

    Scorciapino, Mariano A; Sanna, Roberta; Ardu, Andrea; Orrù, Federica; Casu, Mariano; Musinu, Anna; Cannas, Carla

    2013-10-01

    This work presents an in-depth investigation of the molecular interactions in the incorporation mechanism of colloidal hydrophobic-capped nanoparticles into the hydrophilic core of reverse microemulsions. (1)H Nuclear Magnetic Resonance (NMR) was employed to obtain molecular level details of the interaction between the nanoparticles capping amphiphiles and the microemulsion surfactants. The model system of choice involved oleic acid (OAC) and oleylamine (OAM) as capping molecules, while igepal-CO520 was the surfactant. The former were studied both in their "free" state and "ligated" one, i.e., bound to nanoparticles. The latter was investigated either in cyclohexane (micellar solution) or in water/cyclohexane microemulsions. The approach was extremely useful to gain a deeper understanding of the equilibria involved in this complex system (oleic acid capped-Bi2S3 in igepal/water/cyclohexane microemulsions). In difference to previously proposed mechanisms, the experimental data showed that the high affinity of the capping ligands for the reverse micelle interior was the drivingforce for the incorporation of the nanoparticles. A simple ligand-exchange mechanism could be ruled out. The collected information about the nanoparticle incorporation mechanism is extremely useful to develop new synthetic routes with an improved/tuned coating efficiency, in order to tailor the core-shell structure preparation. PMID:23910706

  10. Core shell hybrids based on noble metal nanoparticles and conjugated polymers: synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Fratoddi, Ilaria; Venditti, Iole; Battocchio, Chiara; Polzonetti, Giovanni; Cametti, Cesare; Russo, Maria Vittoria

    2011-12-01

    Noble metal nanoparticles of different sizes and shapes combined with conjugated functional polymers give rise to advanced core shell hybrids with interesting physical characteristics and potential applications in sensors or cancer therapy. In this paper, a versatile and facile synthesis of core shell systems based on noble metal nanoparticles (AuNPs, AgNPs, PtNPs), coated by copolymers belonging to the class of substituted polyacetylenes has been developed. The polymeric shells containing functionalities such as phenyl, ammonium, or thiol pending groups have been chosen in order to tune hydrophilic and hydrophobic properties and solubility of the target core shell hybrids. The Au, Ag, or Pt nanoparticles coated by poly(dimethylpropargylamonium chloride), or poly(phenylacetylene-co-allylmercaptan). The chemical structure of polymeric shell, size and size distribution and optical properties of hybrids have been assessed. The mean diameter of the metal core has been measured (about 10-30 nm) with polymeric shell of about 2 nm.

  11. Altering the structure and properties of iron oxide nanoparticles and graphene oxide/iron oxide composites by urea

    NASA Astrophysics Data System (ADS)

    Naghdi, Samira; Rhee, Kyong Yop; Jaleh, Babak; Park, Soo Jin

    2016-02-01

    Iron oxide (Fe2O3) nanoparticles were grown on graphene oxide (GO) using a simple microwave-assisted method. The effects of urea concentration on Fe2O3 nanoparticles and GO/Fe2O3 composite were examined. The as-prepared samples were characterized using X-ray powder diffraction, Raman spectroscopy, and transmission electron microscopy. The Fe2O3 nanoparticles were uniformly developed on GO sheets. The results showed that urea affects both Fe2O3 morphology and particle size. In the absence of urea, the Fe2O3 nanostructures exhibited a rod-like morphology. However, increasing urea concentration altered the morphology and decreased the particle size. The Raman results of GO/Fe2O3 showed that the intensity ratio of D band to G band (ID/IG) was decreased by addition of urea, indicating that urea can preserve the GO sheets during synthesis of the composite from exposing more defects. The surface area and thermal stability of GO/Fe2O3 and Fe2O3 were compared using the Brunauer-Emmett-Teller method and thermal gravimetric analysis, respectively. The results showed that the increased concentration of urea induced a larger surface area with more active sites in the Fe2O3 nanoparticles. However, the increase in urea concentration led to decreased thermal stability of the Fe2O3 nanoparticles. The magnetic properties of Fe2O3 nanoparticles were characterized by a vibrating sample magnetometer and results revealed that the magnetic properties of Fe2O3 nanoparticles are affected by the morphology.

  12. Magnetic Iron Oxide Nanoparticles for Multimodal Imaging and Therapy of Cancer

    PubMed Central

    Thomas, Reju; Park, In-Kyu; Jeong, Yong Yeon

    2013-01-01

    Superparamagnetic iron oxide nanoparticles (SPION) have emerged as an MRI contrast agent for tumor imaging due to their efficacy and safety. Their utility has been proven in clinical applications with a series of marketed SPION-based contrast agents. Extensive research has been performed to study various strategies that could improve SPION by tailoring the surface chemistry and by applying additional therapeutic functionality. Research into the dual-modal contrast uses of SPION has developed because these applications can save time and effort by reducing the number of imaging sessions. In addition to multimodal strategies, efforts have been made to develop multifunctional nanoparticles that carry both diagnostic and therapeutic cargos specifically for cancer. This review provides an overview of recent advances in multimodality imaging agents and focuses on iron oxide based nanoparticles and their theranostic applications for cancer. Furthermore, we discuss the physiochemical properties and compare different synthesis methods of SPION for the development of multimodal contrast agents. PMID:23912234

  13. Structural diversity in iron oxide nanoparticle assemblies as directed by particle morphology and orientation.

    PubMed

    Disch, Sabrina; Wetterskog, Erik; Hermann, Raphaël P; Korolkov, Denis; Busch, Peter; Boesecke, Peter; Lyon, Olivier; Vainio, Ulla; Salazar-Alvarez, German; Bergström, Lennart; Brückel, Thomas

    2013-05-01

    The mesostructure of ordered arrays of anisotropic nanoparticles is controlled by a combination of packing constraints and interparticle interactions, two factors that are strongly dependent on the particle morphology. We have investigated how the degree of truncation of iron oxide nanocubes controls the mesostructure and particle orientation in drop cast mesocrystal arrays. The combination of grazing incidence small-angle X-ray scattering and scanning electron microscopy shows that mesocrystals of highly truncated cubic nanoparticles assemble in an fcc-type mesostructure, similar to arrays formed by iron oxide nanospheres, but with a significantly reduced packing density and displaying two different growth orientations. Strong satellite reflections in the GISAXS pattern indicate a commensurate mesoscopic superstructure that is related to stacking faults in mesocrystals of the anisotropic nanocubes. Our results show how subtle variation in shape anisotropy can induce oriented arrangements of nanoparticles of different structures and also create mesoscopic superstructures of larger periodicity.

  14. Determination of anisotropy constants of protein encapsulated iron oxide nanoparticles by electron magnetic resonance

    NASA Astrophysics Data System (ADS)

    Li, Hongyan; Klem, Michael T.; Sebby, Karl B.; Singel, David J.; Young, Mark; Douglas, Trevor; Idzerda, Yves U.

    2009-02-01

    Angle-dependent electron magnetic resonance was performed on 4.9, 8.0, and 19 nm iron oxide nanoparticles encapsulated within protein capsids and suspended in water. Measurements were taken at liquid nitrogen temperature after cooling in a 1 T field to partially align the particles. The angle dependence of the shifts in the resonance field for the iron oxide nanoparticles (synthesized within Listeria-Dps, horse spleen ferritin, and cowpea chlorotic mottle virus) all show evidence of a uniaxial anisotropy. Using a Boltzmann distribution for the particles' easy-axis direction, we are able to use the resonance field shifts to extract a value for the anisotropy energy, showing that the anisotropy energy density increases with decreasing particle size. This suggests that surface anisotropy plays a significant role in magnetic nanoparticles of this size.

  15. Surface modification of iron oxide nanoparticles and their conjuntion with water soluble polymers for biomedical application

    NASA Astrophysics Data System (ADS)

    Thanh Huong, Nguyen; Thi Kieu Giang, Lam; Thanh Binh, Nguyen; Minh, Le Quoc

    2009-09-01

    Superparamagnetic iron oxide nanoparticles (SPION) coated with suitable bio-compatible substances have been used in biomedicine, particularly in magnetic resonance imaging (MRI), tissue engineering, and hyperthermia and drug delivery. In this study, we describe the synthesis of SPION and its surface modification for in-vitro experiments. The particle diameter and structure were estimated by FESEM, TEM, XRD analyses. The saturation magnetization was characterized. SPION with a mean size of 12 nm have been prepared under N2 atmosphere, with support of natural polymeric starch, by controlling chemical coprecipitation of magnetite phase from aqueous solutions containing suitable salts ratios of Fe2+ and Fe3+. The surface of SPION-nanoparticles was treated with a coordinatable agent for higher dispersion ability in water and remaining the superparamagnetic behavior. The prepared iron oxide nanoparticles were coated with starch, dextran, PEG or MPEG to extend the application potential in the quite different engineering field of nano biomedicine.

  16. Increased brain uptake of targeted nanoparticles by adding an acid-cleavable linkage between transferrin and the nanoparticle core.

    PubMed

    Clark, Andrew J; Davis, Mark E

    2015-10-01

    Most therapeutic agents are excluded from entering the central nervous system by the blood-brain barrier (BBB). Receptor mediated transcytosis (RMT) is a common mechanism used by proteins, including transferrin (Tf), to traverse the BBB. Here, we prepared Tf-containing, 80-nm gold nanoparticles with an acid-cleavable linkage between the Tf and the nanoparticle core to facilitate nanoparticle RMT across the BBB. These nanoparticles are designed to bind to Tf receptors (TfRs) with high avidity on the blood side of the BBB, but separate from their multidentate Tf-TfR interactions upon acidification during the transcytosis process to allow release of the nanoparticle into the brain. These targeted nanoparticles show increased ability to cross an in vitro model of the BBB and, most important, enter the brain parenchyma of mice in greater amounts in vivo after systemic administration compared with similar high-avidity nanoparticles containing noncleavable Tf. In addition, we investigated this design with nanoparticles containing high-affinity antibodies (Abs) to TfR. With the Abs, the addition of the acid-cleavable linkage provided no improvement to in vivo brain uptake for Ab-containing nanoparticles, and overall brain uptake was decreased for all Ab-containing nanoparticles compared with Tf-containing ones. These results are consistent with recent reports of high-affinity anti-TfR Abs trafficking to the lysosome within BBB endothelium. In contrast, high-avidity, Tf-containing nanoparticles with the acid-cleavable linkage avoid major endothelium retention by shedding surface Tf during their transcytosis. PMID:26392563

  17. Increased brain uptake of targeted nanoparticles by adding an acid-cleavable linkage between transferrin and the nanoparticle core.

    PubMed

    Clark, Andrew J; Davis, Mark E

    2015-10-01

    Most therapeutic agents are excluded from entering the central nervous system by the blood-brain barrier (BBB). Receptor mediated transcytosis (RMT) is a common mechanism used by proteins, including transferrin (Tf), to traverse the BBB. Here, we prepared Tf-containing, 80-nm gold nanoparticles with an acid-cleavable linkage between the Tf and the nanoparticle core to facilitate nanoparticle RMT across the BBB. These nanoparticles are designed to bind to Tf receptors (TfRs) with high avidity on the blood side of the BBB, but separate from their multidentate Tf-TfR interactions upon acidification during the transcytosis process to allow release of the nanoparticle into the brain. These targeted nanoparticles show increased ability to cross an in vitro model of the BBB and, most important, enter the brain parenchyma of mice in greater amounts in vivo after systemic administration compared with similar high-avidity nanoparticles containing noncleavable Tf. In addition, we investigated this design with nanoparticles containing high-affinity antibodies (Abs) to TfR. With the Abs, the addition of the acid-cleavable linkage provided no improvement to in vivo brain uptake for Ab-containing nanoparticles, and overall brain uptake was decreased for all Ab-containing nanoparticles compared with Tf-containing ones. These results are consistent with recent reports of high-affinity anti-TfR Abs trafficking to the lysosome within BBB endothelium. In contrast, high-avidity, Tf-containing nanoparticles with the acid-cleavable linkage avoid major endothelium retention by shedding surface Tf during their transcytosis.

  18. Simultaneous in-situ synthesis and characterization of Co@Cu core-shell nanoparticle arrays

    DOE PAGESBeta

    McKeown, Joseph T.; Wu, Yueying; Fowlkes, Jason D.; Rack, Philip D.; Campbell, Geoffrey H.

    2014-12-23

    Core-shell nanostructures have attracted much attention due to their unique and tunable properties relative to bulk structures of the same materials, making core-shell nanoparticles candidates for a variety of applications with multiple functionalities.[1,2] Intriguing magnetic behavior can be tailored by variation of size, interface, crystal orientation, and composition, and core-shell nanostructures with noble-metal shells yield novel optical responses[3] and enhanced electrocatalytic activity.[4

  19. Lectin-functionalized magnetic iron oxide nanoparticles for reproductive improvement

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Semen ejaculates contain heterogeneous sperm populations that can jeopardize male fertility. Recent development of nanotechnology in physiological systems may have applications in reproductive biology. Here, we used magnetic nanoparticles as a novel strategy for sperm purification to imp...

  20. Purification of Lysosomes Using Supraparamagnetic Iron Oxide Nanoparticles (SPIONs).

    PubMed

    Rofe, Adam P; Pryor, Paul R

    2016-04-01

    Lysosomes can be rapidly isolated from tissue culture cells using supraparamagnetic iron oxide particles (SPIONs). In this protocol, colloidal iron dextran (FeDex) particles, a type of SPION, are taken up by cultured mouse macrophage cells via the endocytic pathway. The SPIONs accumulate in lysosomes, the end point of the endocytic pathway, permitting the lysosomes to be isolated magnetically. The purified lysosomes are suitable for in vitro fusion assays or for proteomic analysis. PMID:27037068

  1. Purification of Lysosomes Using Supraparamagnetic Iron Oxide Nanoparticles (SPIONs).

    PubMed

    Rofe, Adam P; Pryor, Paul R

    2016-04-01

    Lysosomes can be rapidly isolated from tissue culture cells using supraparamagnetic iron oxide particles (SPIONs). In this protocol, colloidal iron dextran (FeDex) particles, a type of SPION, are taken up by cultured mouse macrophage cells via the endocytic pathway. The SPIONs accumulate in lysosomes, the end point of the endocytic pathway, permitting the lysosomes to be isolated magnetically. The purified lysosomes are suitable for in vitro fusion assays or for proteomic analysis.

  2. Accumulation of magnetic iron oxide nanoparticles coated with variably sized polyethylene glycol in murine tumors

    NASA Astrophysics Data System (ADS)

    Larsen, Esben Kjær Unmack; Nielsen, Thomas; Wittenborn, Thomas; Rydtoft, Louise Munk; Lokanathan, Arcot R.; Hansen, Line; Østergaard, Leif; Kingshott, Peter; Howard, Kenneth A.; Besenbacher, Flemming; Nielsen, Niels Chr.; Kjems, Jørgen

    2012-03-01

    Iron oxide nanoparticles have found widespread applications in different areas including cell separation, drug delivery and as contrast agents. Due to water insolubility and stability issues, nanoparticles utilized for biological applications require coatings such as the commonly employed polyethylene glycol (PEG). Despite its frequent use, the influence of PEG coatings on the physicochemical and biological properties of iron nanoparticles has hitherto not been studied in detail. To address this, we studied the effect of 333-20 000 Da PEG coatings that resulted in larger hydrodynamic size, lower surface charge, longer circulation half-life, and lower uptake in macrophage cells when the particles were coated with high molecular weight (Mw) PEG molecules. By use of magnetic resonance imaging, we show coating-dependent in vivo uptake in murine tumors with an optimal coating Mw of 10 000 Da.Iron oxide nanoparticles have found widespread applications in different areas including cell separation, drug delivery and as contrast agents. Due to water insolubility and stability issues, nanoparticles utilized for biological applications require coatings such as the commonly employed polyethylene glycol (PEG). Despite its frequent use, the influence of PEG coatings on the physicochemical and biological properties of iron nanoparticles has hitherto not been studied in detail. To address this, we studied the effect of 333-20 000 Da PEG coatings that resulted in larger hydrodynamic size, lower surface charge, longer circulation half-life, and lower uptake in macrophage cells when the particles were coated with high molecular weight (Mw) PEG molecules. By use of magnetic resonance imaging, we show coating-dependent in vivo uptake in murine tumors with an optimal coating Mw of 10 000 Da. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr11554a

  3. Core-shell Au-Pd nanoparticles as cathode catalysts for microbial fuel cell applications

    NASA Astrophysics Data System (ADS)

    Yang, Gaixiu; Chen, Dong; Lv, Pengmei; Kong, Xiaoying; Sun, Yongming; Wang, Zhongming; Yuan, Zhenhong; Liu, Hui; Yang, Jun

    2016-10-01

    Bimetallic nanoparticles with core-shell structures usually display enhanced catalytic properties due to the lattice strain created between the core and shell regions. In this study, we demonstrate the application of bimetallic Au-Pd nanoparticles with an Au core and a thin Pd shell as cathode catalysts in microbial fuel cells, which represent a promising technology for wastewater treatment,