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1

Using shape effects to target antibody-coated nanoparticles to lung and brain endothelium  

PubMed Central

Vascular endothelium offers a variety of therapeutic targets for the treatment of cancer, cardiovascular diseases, inflammation, and oxidative stress. Significant research has been focused on developing agents to target the endothelium in diseased tissues. This includes identification of antibodies against adhesion molecules and neovascular expression markers or peptides discovered using phage display. Such targeting molecules also have been used to deliver nanoparticles to the endothelium of the diseased tissue. Here we report, based on in vitro and in vivo studies, that the specificity of endothelial targeting can be enhanced further by engineering the shape of ligand-displaying nanoparticles. In vitro studies performed using microfluidic systems that mimic the vasculature (synthetic microvascular networks) showed that rod-shaped nanoparticles exhibit higher specific and lower nonspecific accumulation under flow at the target compared with their spherical counterparts. Mathematical modeling of particle–surface interactions suggests that the higher avidity and specificity of nanorods originate from the balance of polyvalent interactions that favor adhesion and entropic losses as well as shear-induced detachment that reduce binding. In vivo experiments in mice confirmed that shape-induced enhancement of vascular targeting is also observed under physiological conditions in lungs and brain for nanoparticles displaying anti–intracellular adhesion molecule 1 and anti-transferrin receptor antibodies. PMID:23754411

Kolhar, Poornima; Anselmo, Aaron C.; Gupta, Vivek; Pant, Kapil; Prabhakarpandian, Balabhaskar; Ruoslahti, Erkki; Mitragotri, Samir

2013-01-01

2

Magnetic nanoparticles  

Microsoft Academic Search

Intrinsic properties of magnetic nanoparticles are reviewed, with special emphasis on the effects of finite size on zero-temperature spin ordering, magnetic excitations, and relaxation. Effects on zero-temperature spin ordering include moment enhancement due to band narrowing in 3d transition metal particles, surface spin disorder in ferrite particles, and multi-sublattice states in antiferromagnetic oxide particles. Magnetic excitations include discretized spin wave

R. H Kodama

1999-01-01

3

Magnetic Nanoparticle Sensors  

PubMed Central

Many types of biosensors employ magnetic nanoparticles (diameter = 5–300 nm) or magnetic particles (diameter = 300–5,000 nm) which have been surface functionalized to recognize specific molecular targets. Here we cover three types of biosensors that employ different biosensing principles, magnetic materials, and instrumentation. The first type consists of magnetic relaxation switch assay-sensors, which are based on the effects magnetic particles exert on water proton relaxation rates. The second type consists of magnetic particle relaxation sensors, which determine the relaxation of the magnetic moment within the magnetic particle. The third type is magnetoresistive sensors, which detect the presence of magnetic particles on the surface of electronic devices that are sensitive to changes in magnetic fields on their surface. Recent improvements in the design of magnetic nanoparticles (and magnetic particles), together with improvements in instrumentation, suggest that magnetic material-based biosensors may become widely used in the future. PMID:22408498

Koh, Isaac; Josephson, Lee

2009-01-01

4

Guidance of stem cells to a target destination in vivo by magnetic nanoparticles in a magnetic field.  

PubMed

Stem cells contribute to physiological processes such as postischemic neovascularization and vascular re-endothelialization, which help regenerate myocardial defects or repair vascular injury. However, therapeutic efficacy of stem cell transplantation is often limited by inefficient homing of systemically administered cells, which results in a low number of cells accumulating at sites of pathology. In this study, anti-CD34 antibody-coated magnetic nanoparticles (Fe3O4@PEG-CD34) are shown to have high affinity to stem cells. The results of hemolysis rate and activated partial thromboplastin time (APTT) tests indicate that such nanoparticle may be used safely in the blood system. In vitro studies showed that a nanoparticle concentration of 100 ?g/mL gives rise to a significant increase in cell retention using an applicable permanent magnet, exerting minimal negative effect on cell viability and migration. Subsequent in vivo studies indicate that nanopartical can specifically bind stem cells with good magnetic response. Anti-CD34 antibody coated magnetic nanoparticle may be used to help deliver stem cells to a lesion site in the body for better treatment. PMID:23749081

Chen, Jialong; Huang, Nan; Ma, Baolong; Maitz, Manfred F; Wang, Juan; Li, Jingan; Li, Quanli; Zhao, Yuancong; Xiong, Kaiqin; Liu, Xin

2013-07-10

5

Magnetic interactions between nanoparticles  

PubMed Central

Summary We present a short overview of the influence of inter-particle interactions on the properties of magnetic nanoparticles. Strong magnetic dipole interactions between ferromagnetic or ferrimagnetic particles, that would be superparamagnetic if isolated, can result in a collective state of nanoparticles. This collective state has many similarities to spin-glasses. In samples of aggregated magnetic nanoparticles, exchange interactions are often important and this can also lead to a strong suppression of superparamagnetic relaxation. The temperature dependence of the order parameter in samples of strongly interacting hematite nanoparticles or goethite grains is well described by a simple mean field model. Exchange interactions between nanoparticles with different orientations of the easy axes can also result in a rotation of the sub-lattice magnetization directions. PMID:21977409

Hansen, Mikkel Fougt; Frandsen, Cathrine

2010-01-01

6

Chemiluminescence immunoassay for the rapid and sensitive detection of antibody against porcine parvovirus by using horseradish peroxidase/detection antibody-coated gold nanoparticles as nanoprobes.  

PubMed

A rapid, simple, facile, sensitive and enzyme-amplified chemiluminescence immunoassay (CLIA) method to detect antibodies against porcine parvovirus has been developed. Horseradish peroxidase (HRP) and the detection antibody were simultaneously co-immobilized on the surface of gold nanoparticles using the electrostatic method to form gold nanoparticle-based nanoprobes. This nanoprobe was employed in a sandwich-type CLIA, which enables CL signal readout from enzymatic catalysis and results in signal amplification. The presence of porcine parvovirus infection was determined in porcine parvovirus antibodies by measuring the CL intensity caused by the reaction of HRP-luminol with H2 O2 . Under optimal conditions, the obtained calibration plot for the standard positive serum was approximately linear within the dilution range of 1:80 to 1:5120. The limit of detection for the assay was 1:10,240 (S/N = 3), which is much lower than that typically achieved with an enzyme-linked immunosorbent assay (1:160; S/N = 3). A series of repeatability measurements using 1:320-fold diluted standard positive serum gave reproducible results with a relative standard deviation of 4.9% (n = 11). The ability of the immunosensor to analyze clinical samples was tested on porcine sera. The immunosensor had an efficiency of 90%, a sensitivity of 93.3%, and a specificity of 87.5% relative to the enzyme-linked immunosorbent assay results. PMID:23832716

Zhou, Yuan; Zhou, Tao; Zhou, Rui; Hu, Yonggang

2014-06-01

7

Magnetism in gold nanoparticles  

NASA Astrophysics Data System (ADS)

Gold nanoparticles currently elicit an intense and very broad research activity because of their peculiar properties. Be it in catalysis, optics, electronics, sensing or theranostics, new applications are found daily for these materials. Approximately a decade ago a report was published with magnetometry data showing that gold nanoparticles, most surprisingly, could also be magnetic, with features that the usual rules of magnetism were unable to explain. Many ensuing experimental papers confirmed this observation, although the reported magnetic behaviours showed a great variability, for unclear reasons. In this review, most of the experimental facts pertaining to ``magnetic gold'' are summarized. The various theories put forth for explaining this unexpected magnetism are presented and discussed. We show that despite much effort, a satisfying explanation is still lacking and that the field of hypotheses should perhaps be widened.

Nealon, Gareth L.; Donnio, Bertrand; Greget, Romain; Kappler, Jean-Paul; Terazzi, Emmanuel; Gallani, Jean-Louis

2012-08-01

8

Effective magnetic moment of magnetic multicore nanoparticles  

NASA Astrophysics Data System (ADS)

We carry out Monte Carlo simulations to study the effective magnetic moment ?eff in the low-field region of magnetic multicore nanoparticles. Transmission electron microscopy and scanning electron microscopy images show that these particles contain a number of magnetic nanocrystals (MNCs) randomly packed in a single cluster of total volume Vtot . We illustrate how the initial magnetic susceptibility ?0 of magnetic multicore nanoparticles can be straightforward derived from ?eff computed at zero magnetic field. We observe that dipolar interactions between MNCs and polydispersity of the MNCs contribute to increase and to decrease ?eff/Vtot , respectively, while magnetic anisotropy of the MNCs does not show any effect. In all three cases, ?eff/Vtot can be described by a linear relation to (?B/kBT)2 that we analytically derived for low applied fields.

Schaller, Vincent; Wahnström, Göran; Sanz-Velasco, Anke; Gustafsson, Stefan; Olsson, Eva; Enoksson, Peter; Johansson, Christer

2009-09-01

9

Magnetic Nanoparticle Targeted Hyperthermia of Cutaneous Staphylococcus aureus Infection  

E-print Network

Magnetic Nanoparticle Targeted Hyperthermia of Cutaneous Staphylococcus aureus Infection MIN-HO KIM to rapidly heat magnetic nanoparticles that are bound to Staphylococcus aureus (S. aureus). The antimicrobial magnetic field, S. aureus biofilm, Magnetic nanoparticle. INTRODUCTION Staphylococcus aureus (S. aureus

Simon, Scott I.

10

Interaction of erythrocytes with magnetic nanoparticles.  

PubMed

Internalization of biocompatible magnetic nanoparticles by red blood cells (RBCs) is a key issue for opportunities of new applications in the biomedical field. In this study, we used in vitro tests to provide evidences of magnetic nanoparticle internalization by mice red blood cells. The internalization process depends upon the nanoparticle concentration and the nanoparticle hydrodynamic radii. The cell internalization of surface-coated maghemite nanoparticles was indirectly tracked by Raman spectroscopy and directly observed using transmission electron microscopy. The observation of nanoparticle cell uptaking using in vitro experiments represents an important breakthrough for the application of nanomagnetism in diagnosis and therapy of RBC-related diseases. PMID:17450877

Soler, Maria A G; Báo, Sônia N; Alcântara, Gustavo B; Tibúrcio, Victor H S; Paludo, Giane R; Santana, José F B; Guedes, Maria H; Lima, Emilia C D; Lacava, Zulmira G M; Morais, Paulo C

2007-03-01

11

Magnetic nanoparticles for tunable microwave metamaterials  

NASA Astrophysics Data System (ADS)

Commonly, metamaterials are electrically engineered systems with optimized spatial arrangement of subwavelength sized metal and dielectric components. We explore alternative methods based on use of magnetic inclusions, such as magnetic nanoparticles, which can allow permeability of a composite to be tuned from negative to positive at the range of magnetic resonance. To better understand effects of particle size and magnetization dynamics, we performed electron magnetic resonance study on several varieties of magnetic nanoparticles and determined potential of nanoparticle use as building blocks for tunable microwave metamaterials.

Noginova, Natalia; Williams, Quincy Leon; Dallas, Panagiotis; Giannelis, Emmanuel P.

12

Size and polydispersity effect on the magnetization of densely packed magnetic nanoparticles.  

E-print Network

Size and polydispersity effect on the magnetization of densely packed magnetic nanoparticles Paris 13, 93017 Bobigny, France. The magnetic properties of densely packed magnetic nanoparticles (MNP) assemblies are investi- gated from Monte Carlo simulations. The case of iron oxide nanoparticles

Boyer, Edmond

13

Bioinspired synthesis of magnetic nanoparticles  

SciTech Connect

The synthesis of magnetic nanoparticles has long been an area of active research. Magnetic nanoparticles can be used in a wide variety of applications such as magnetic inks, magnetic memory devices, drug delivery, magnetic resonance imaging (MRI) contrast agents, and pathogen detection in foods. In applications such as MRI, particle uniformity is particularly crucial, as is the magnetic response of the particles. Uniform magnetic particles with good magnetic properties are therefore required. One particularly effective technique for synthesizing nanoparticles involves biomineralization, which is a naturally occurring process that can produce highly complex nanostructures. Also, the technique involves mild conditions (ambient temperature and close to neutral pH) that make this approach suitable for a wide variety of materials. The term 'bioinspired' is important because biomineralization research is inspired by the naturally occurring process, which occurs in certain microorganisms called 'magnetotactic bacteria'. Magnetotactic bacteria use biomineralization proteins to produce magnetite crystals having very good uniformity in size and morphology. The bacteria use these magnetic particles to navigate according to external magnetic fields. Because these bacteria synthesize high quality crystals, research has focused on imitating aspects of this biomineralization in vitro. In particular, a biomineralization iron-binding protein found in a certain species of magnetotactic bacteria, magnetospirillum magneticum, AMB-1, has been extracted and used for in vitro magnetite synthesis; Pluronic F127 gel was used to increase the viscosity of the reaction medium to better mimic the conditions in the bacteria. It was shown that the biomineralization protein mms6 was able to facilitate uniform magnetite synthesis. In addition, a similar biomineralization process using mms6 and a shorter version of this protein, C25, has been used to synthesize cobalt ferrite particles. The overall goal of this project is to understand the mechanism of magnetite particle synthesis in the presence of the biomineralization proteins, mms6 and C25. Previous work has hypothesized that the mms6 protein helps to template magnetite and cobalt ferrite particle synthesis and that the C25 protein templates cobalt ferrite formation. However, the effect of parameters such as the protein concentration on the particle formation is still unknown. It is expected that the protein concentration significantly affects the nucleation and growth of magnetite. Since the protein provides iron-binding sites, it is expected that magnetite crystals would nucleate at those sites. In addition, in the previous work, the reaction medium after completion of the reaction was in the solution phase, and magnetic particles had a tendency to fall to the bottom of the medium and aggregate. The research presented in this thesis involves solid Pluronic gel phase reactions, which can be studied readily using small-angle x-ray scattering, which is not possible for the solution phase experiments. In addition, the concentration effect of both of the proteins on magnetite crystal formation was studied.

David, Anand

2009-05-26

14

Dual immobilization and magnetic manipulation of magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

By suitably bio-functionalizing the surfaces, magnetic nanoparticles are able to bind specific biomolecules, and may serve as vectors for delivering bio-entities to target tissues. In this work, the synthesis of bio-functionalized magnetic nanoparticles with two kinds of bio-probes is developed. Here, the stem cell is selected as a to-be-delivered bio-entity and infarcted myocardium is the target issue. Thus, cluster designation-34 (CD-34) on stem cell and creatine kinase-MB (CK-MB) (or troponin I) on infarcted myocardium are the specific biomolecules to be bound with bio-functionalized magnetic nanoparticles. In addition to demonstrating the co-coating of two kinds of bio-probes on a magnetic nanoparticle, the feasibility of manipulation on bio-functionalized magnetic nanoparticles by external magnetic fields is investigated.

Yang, S. Y.; Jian, Z. F.; Horng, H. E.; Hong, Chin-Yih; Yang, H. C.; Wu, C. C.; Lee, Y. H.

15

Temperature Dependence of Magnetic Nanoparticles for Metamaterials  

NASA Astrophysics Data System (ADS)

Commonly, metamaterials are systems with engineered electric response, based on optimized spatial arrangement of sub-wavelength sized metal and dielectric components. We explore alternative methods based on use of magnetic inclusions, such as magnetic nanoparticles, which can allow microwave permeability of a composite to be tuned from negative to positive at the range of magnetic resonance. Several systems with magnetic nanoparticles of different size were experimentally tested for estimate their potential as building blocks for metamaterials. Magnetic resonance studies were performed in the limits of diluted non-interacting solutions of superparamagnetic nanoparticles in liquid form and high concentrations of particles in solids at different temperatures. Broadening of the EMR signal was observed upon increase in the particle size and concentration, due to effects of anisotropy and dipolar interaction. Microwave permeability was estimated in solid composites. In dense systems with 5 nm iron oxide nanoparticles it can be tuned from --0.8 to 2 by the external magnetic field.

Williams, Quincy; Noginova, Natalia; Dallas, Pagnagiotis; Giannelis, Emmanuel

2013-03-01

16

In vivo heating of magnetic nanoparticles in alternating magnetic field.  

PubMed

We have evaluated heating capabilities of new magnetic nanoparticles. In in vitro experiments they were exposed to an alternating magnetic field with frequency 3.5 MHz and induction 1.5 mT produced in three turn pancake coil. In in vivo experiments rats with injected magnetic nanoparticles were also exposed to an ac field. An optimal increase of temperature of the tumor to 44 degrees C was achieved after 10 minutes of exposure. Obtained results showed that magnetic nanoparticles may be easily heated in vitro as well as in vivo, and may be therefore useful for hyperthermic therapy of cancer. PMID:15377087

Babincová, M; Altanerová, V; Altaner, C; Cicmanec, P; Babinec, P

2004-08-01

17

Measuring magnetic correlations in nanoparticle assemblies  

NASA Astrophysics Data System (ADS)

We illustrate how to extract correlations between magnetic moments in assemblies of nanoparticles from, e.g., electron holography data providing the combined knowledge of particle size distribution, inter-particle distances, and magnitude and orientation of each magnetic moment within a nanoparticle superstructure, We show, based on simulated data, how to build a radial/angular pair distribution function f(r,?) encoding the spatial and angular difference between every pair of magnetic moments. A scatter-plot of f(r,?) reveals the degree of structural and magnetic order present, and hence provides a measure of the strength and range of magnetic correlations.

Beleggia, M.; Frandsen, C.

2014-06-01

18

Properties and biomedical applications of magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles have a number of unique properties, making them promising agents for applications in medicine including magnetically targeted drug delivery, magnetic hyperthermia, magnetic resonance imaging, and radiation therapy. They are biocompatible and can also be coated with biocompatible surfactants, which may be further functionalized with optically and therapeutically active molecules. These nanoparticles can be manipulated with non-invasive external magnetic field to produce heat, target specific site, and monitor their distribution in vivo. Within this framework, we have investigated a number of biomedical applications of these nanoparticles. We synthesized a thermosensitive microgel with iron oxide adsorbed on its surface. An alternating magnetic field applied to these nanocomposites heated the system and triggered the release of an anticancer drug mitoxantrone. We also parameterized the chain length dependence of drug release from dextran coated iron oxide nanoparticles, finding that both the release rate and equilibrium release fraction depend on the molecular mass of the surfactant. Finally, we also localized dextran coated iron oxide nanoparticles labeled with tat peptide to the cell nucleus, which permits this system to be used for a variety of biomedical applications. Beyond investigating magnetic nanoparticles for biomedical applications, we also studied their magnetohydrodynamic and dielectric properties in solution. Magnetohydrodynamic properties of ferrofluid can be controlled by appropriate selection of surfactant and deielctric measurement showed magnetodielectric coupling in this system. We also established that some complex low temperature spin structures are suppressed in Mn3O4 nanoparticles, which has important implications for nanomagnetic devices. Furthermore, we explored exchange bias effects in Ni-NiO core-shell nanoparticles. Finally, we also performed extensive magnetic studies in nickel metalhydride (NiMH) batteries to determine the size of Ni clusters, which plays important role on catalyzing the electrochemical reaction and powering Ni-MH batteries.

Regmi, Rajesh Kumar

19

Terahertz magnetic modulator based on magnetically clustered nanoparticles  

NASA Astrophysics Data System (ADS)

Random orientation of liquid-suspended magnetic nanoparticles (Ferrofluids) gives rise to a zero net magnetic orientation. An external magnetic field tends to align these nanoparticles into clusters, leading to a strong linear dichroism on a propagating wave. Using 10 nm-sized Fe3O4, we experimentally realize a polarization-sensitive magnetic modulator operating at terahertz wavelengths. We reached a modulation depth of 66% using a field as low as 35 mT. The proposed concept offers a solution towards fundamental terahertz magnetic modulators.

Shalaby, Mostafa; Peccianti, Marco; Ozturk, Yavuz; Al-Naib, Ibraheem; Hauri, Christoph P.; Morandotti, Roberto

2014-10-01

20

Application of Magnetic Nanoparticles to Gene Delivery  

PubMed Central

Nanoparticle technology is being incorporated into many areas of molecular science and biomedicine. Because nanoparticles are small enough to enter almost all areas of the body, including the circulatory system and cells, they have been and continue to be exploited for basic biomedical research as well as clinical diagnostic and therapeutic applications. For example, nanoparticles hold great promise for enabling gene therapy to reach its full potential by facilitating targeted delivery of DNA into tissues and cells. Substantial progress has been made in binding DNA to nanoparticles and controlling the behavior of these complexes. In this article, we review research on binding DNAs to nanoparticles as well as our latest study on non-viral gene delivery using polyethylenimine-coated magnetic nanoparticles. PMID:21747701

Kami, Daisuke; Takeda, Shogo; Itakura, Yoko; Gojo, Satoshi; Watanabe, Masatoshi; Toyoda, Masashi

2011-01-01

21

Synthesis and Characterization of Magnetic Nanoparticles with High Magnetization and Good Oxidation Resistibility  

E-print Network

Magnetic nanoparticles attract increasing attention because of their current and potential biomedical applications, such as, magnetically targeted and controlled drug delivery, magnetic hyperthermia and magnetic extraction. ...

Yu, Shi

22

Dynamics of magnetic nanoparticle in a viscous liquid: Application to magnetic nanoparticle hyperthermia  

NASA Astrophysics Data System (ADS)

It is shown that the magnetic dynamics of an assembly of nanoparticles dispersed in a viscous liquid differs significantly from the behavior of the same assembly of nanoparticles immobilized in a solid matrix. For an assembly of magnetic nanoparticles in a liquid two characteristic mode for stationary magnetization oscillations are found that can be called the viscous and magnetic modes, respectively. In the viscous mode, which occurs for small amplitude of the alternating magnetic field H0 as compared to the particle anisotropy field Hk, the particle rotates in the liquid as a whole. In a stationary motion the unit magnetization vector and the director, describing the spatial orientation of the particle, move in unison, but the phase of oscillations of these vectors is shifted relative to that of the alternating magnetic field. Therefore, for the viscous mode the energy absorption is mainly due to viscous losses associated with the particle rotation in the liquid. In the opposite regime, H0 ? Hk, the director oscillates only slightly near the external magnetic field direction, whereas the unit magnetization vector sharply jumps between magnetic potential wells. Thus, a complete orientation of the assembly of nanoparticles in the liquid occurs in the alternating magnetic field of sufficient amplitude. As a result, large specific absorption rates, of the order of 1 kW/g, can be obtained for an assembly of magnetic nanoparticles in viscous liquid in the transient, H0 ˜ 0.5Hk, and magnetic modes at moderate frequency and alternating magnetic field amplitude.

Usov, N. A.; Liubimov, B. Ya.

2012-07-01

23

Magnetic Polystyrene Nanocomposites Reinforced with Magnetite Nanoparticles  

E-print Network

Magnetic Polystyrene Nanocomposites Reinforced with Magnetite Nanoparticles Xingru Yan, Qingliang He, Xi Zhang, Hongbo Gu, Haoran Chen, Qiang Wang, Luyi Sun, Suying Wei,* Zhanhu Guo Polystyrene (PS materials due to the fairly large magnetization and admirable conductive properties.[21] Polystyrene (PS

Guo, John Zhanhu

24

MAGNETIC NANOPARTICLE HYPERTHERMIA IN CANCER TREATMENT  

PubMed Central

The activation of magnetic nanoparticles (mNPs) by an alternating magnetic field (AMF) is currently being explored as technique for targeted therapeutic heating of tumors. Various types of superparamagnetic and ferromagnetic particles, with different coatings and targeting agents, allow for tumor site and type specificity. Magnetic nanoparticle hyperthermia is also being studied as an adjuvant to conventional chemotherapy and radiation therapy. This review provides an introduction to some of the relevant biology and materials science involved in the technical development and current and future use of mNP hyperthermia as clinical cancer therapy. PMID:24348868

Giustini, Andrew J.; Petryk, Alicia A.; Cassim, Shiraz M.; Tate, Jennifer A.; Baker, Ian; Hoopes, P. Jack

2013-01-01

25

Approaches for modeling magnetic nanoparticle dynamics.  

PubMed

Magnetic nanoparticles are useful biological probes as well as therapeutic agents. Several approaches have been used to model nanoparticle magnetization dynamics for both Brownian as well as Neel rotation. Magnetizations are often of interest and can be compared with experimental results. Here we summarize these approaches, including the Stoner-Wohlfarth approach and stochastic approaches including thermal fluctuations. Non-equilibrium-related temperature effects can be described by a distribution function approach (Fokker-Planck equation) or a stochastic differential equation (Langevin equation). Approximate models in several regimes can be derived from these general approaches to simplify implementation. PMID:25271360

Reeves, Daniel B; Weaver, John B

2014-01-01

26

Biocompatible magnetic nanoparticles with high magnetic moment for cancer treatment  

NASA Astrophysics Data System (ADS)

Non-toxic iron oxide naoparticles have extended the boundary in medical world; with size range form 2 to 400 nm they can be compiled with most of the small cells and tissues in living body. We have prepared monodispersive iron-iron oxide core-shell nanoparticles in our novel cluster deposition system. The nanoparticles have very high magnetic moment up to 200 emu/g. To test the nontoxicity and uptake we incubated the nanoparticles coated with dextrin and non-coated iron naoparticles with LXI SCLC lung cancer cells found in rats. Results indicate that both coated and noncoated cells were successfully untaken by the cells indicating that the core-shell nanoparticles are not toxic. Due to the high magnetic moment offered by the nanoparticles we propose that even in low applied external alternating field desired temperature can be reached for hyperthermia treatment in comparison to the commercially available iron oxide nanoparticles (magnetic moment less than 20 emu/g). We also found that our ferromagnetic nanoparticles were uptaken by the cancer cells without adding protamine sulfate, which is normally needed to prevent the coagulation of cells for the commercial nanoparticles. To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.NWS07.B4.5

Sharma, Amit; Qiang, You; Muldoon, Leslie; Meyer, Daniel; Hass, Jamie

2007-05-01

27

Irreversible magnetic properties of carbon nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic properties of powder and glassy samples with carbon nanoparticles. not intentionally doped and doped with Ag, Au and Co, are investigated at temperatures T ~ 3 — 300 K in magnetic fields B up to 5 T. Magnetization M (T) exhibits in low fields of B = 1 — 50 mT a strong irreversibility, which is suppressed above B ~ 1 T. The high-temperature (T ~ 200 — 300 K) dependence of M on B demonstrates a saturation above B ~ 2 T. Magnetic hysteresis is observed already at 300 K. exhibiting a power-law temperature decay of the coercive field. Analysis of the experimental data suggests a concentration of the magnetization close to the surface of the carbon nanoparticles. This is consistent with the origin of magnetism in nanocarbon due to intrinsic surface defects. Deviations of macroscopic and microscopic parameters in the Co-doped sample from those in the other samples imply an influence of the Co ions and/or clusters.

Lähderanta, E.; Lashkul, A. V.; Lisunov, K. G.; Zherebtsov, D. A.; Galimov, D. M.; Titkov, A. N.

2013-01-01

28

Tuning the Magnetic Properties of Nanoparticles  

PubMed Central

The tremendous interest in magnetic nanoparticles (MNPs) is reflected in published research that ranges from novel methods of synthesis of unique nanoparticle shapes and composite structures to a large number of MNP characterization techniques, and finally to their use in many biomedical and nanotechnology-based applications. The knowledge gained from this vast body of research can be made more useful if we organize the associated results to correlate key magnetic properties with the parameters that influence them. Tuning these properties of MNPs will allow us to tailor nanoparticles for specific applications, thus increasing their effectiveness. The complex magnetic behavior exhibited by MNPs is governed by many factors; these factors can either improve or adversely affect the desired magnetic properties. In this report, we have outlined a matrix of parameters that can be varied to tune the magnetic properties of nanoparticles. For practical utility, this review focuses on the effect of size, shape, composition, and shell-core structure on saturation magnetization, coercivity, blocking temperature, and relaxation time. PMID:23912237

Kolhatkar, Arati G.; Jamison, Andrew C.; Litvinov, Dmitri; Willson, Richard C.; Lee, T. Randall

2013-01-01

29

Simulations of magnetic nanoparticle Brownian motion  

E-print Network

Magnetic nanoparticles are useful in many medical applications because they interact with biology on a cellular level thus allowing microenvironmental investigation. An enhanced understanding of the dynamics of magnetic particles may lead to advances in imaging directly in magnetic particle imaging (MPI) or through enhanced MRI contrast and is essential for nanoparticle sensing as in magnetic spectroscopy of Brownian motion (MSB). Moreover, therapeutic techniques like hyperthermia require information about particle dynamics for effective, safe, and reliable use in the clinic. To that end, we have developed and validated a stochastic dynamical model of rotating Brownian nanoparticles from a Langevin equation approach. With no field, the relaxation time toward equilibrium matches Einstein's model of Brownian motion. In a static field, the equilibrium magnetization agrees with the Langevin function. For high frequency or low amplitude driving fields, behavior characteristic of the linearized Debye approximation is reproduced. In a higher field regime where magnetic saturation occurs, the magnetization and its harmonics compare well with the effective field model. On another level, the model has been benchmarked against experimental results, successfully demonstrating that harmonics of the magnetization carry enough information to infer environmental parameters like viscosity and temperature.

Daniel B Reeves; John B Weaver

2014-03-25

30

Simulations of magnetic nanoparticle Brownian motion.  

PubMed

Magnetic nanoparticles are useful in many medical applications because they interact with biology on a cellular level thus allowing microenvironmental investigation. An enhanced understanding of the dynamics of magnetic particles may lead to advances in imaging directly in magnetic particle imaging or through enhanced MRI contrast and is essential for nanoparticle sensing as in magnetic spectroscopy of Brownian motion. Moreover, therapeutic techniques like hyperthermia require information about particle dynamics for effective, safe, and reliable use in the clinic. To that end, we have developed and validated a stochastic dynamical model of rotating Brownian nanoparticles from a Langevin equation approach. With no field, the relaxation time toward equilibrium matches Einstein's model of Brownian motion. In a static field, the equilibrium magnetization agrees with the Langevin function. For high frequency or low amplitude driving fields, behavior characteristic of the linearized Debye approximation is reproduced. In a higher field regime where magnetic saturation occurs, the magnetization and its harmonics compare well with the effective field model. On another level, the model has been benchmarked against experimental results, successfully demonstrating that harmonics of the magnetization carry enough information to infer environmental parameters like viscosity and temperature. PMID:23319830

Reeves, Daniel B; Weaver, John B

2012-12-15

31

Magnetic nanoparticle hyperthermia for prostate cancer.  

PubMed

Magnetic nanoparticles are increasingly used for clinical applications such as drug delivery, magnetic resonance imaging and magnetic fluid hyperthermia. A novel method of interstitial heating of tumours following direct injection of magnetic nanoparticles has been evaluated in humans in recent clinical trials. In prostate cancer this approach has been investigated in two separate phase I studies, employing magnetic nanoparticle thermotherapy alone and in combination with permanent seed brachytherapy. The feasibility and good tolerability was shown in both trials, using the first prototype of an alternating magnetic field applicator. As with any other heating technique, this novel approach requires specific tools for planning, quality control and thermal monitoring, based on appropriate imaging and modelling techniques. In these first clinical trials a newly developed method for planning and non-invasive calculations of the 3-dimensional temperature distribution based on computed tomography was validated. Limiting factors of the new approach at present are patient discomfort at high magnetic field strengths and irregular intratumoural heat distribution. Until these limitations are overcome and thermoablation can safely be applied as a monotherapy, this treatment modality is being evaluated in combination with irradiation in patients with localised prostate cancer. PMID:20653418

Johannsen, Manfred; Thiesen, Burghard; Wust, Peter; Jordan, Andreas

2010-01-01

32

Nanocomposites of magnetic cobalt nanoparticles and cellulose  

NASA Astrophysics Data System (ADS)

Polymeric matrices with stabilized metallic nanoparticles constitute an important class of nanostructured materials, because polymer technology allows fabrication of components with various electronic, magnetic and mechanical properties. The porous cellulose matrix has been shown to be a useful support material for platinum, palladium, silver, copper and nickel nanoparticles. In the present study, nanosized cobalt particles with enhanced magnetic properties were made by chemical reduction within a microcrystalline cellulose (MCC) matrix. Two different chemical reducers, NaBH4 and NaH2PO2, were used, and the so-formed nanoparticles were characterized with X-ray absorption spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. These experimental techniques were used to gain insight into the effect of different synthesis routes on structural properties of the nanoparticles. Magnetic properties of the nanoparticles were studied using a vibrating sample magnetometer. Particles made via the NaBH4 reduction were amorphous Co-B or Co oxide composites with diminished ferromagnetic behaviour and particles made via the NaH2PO2 reduction were well-ordered ferromagnetic hcp cobalt nanocrystals.

Pirkkalainen, K.; Leppänen, K.; Vainio, U.; Webb, M. A.; Elbra, T.; Kohout, T.; Nykänen, A.; Ruokolainen, J.; Kotelnikova, N.; Serimaa, R.

2008-10-01

33

Monodisperse Magnetic Nanoparticles for Theranostic Applications  

PubMed Central

Conspectus The development of highly effective medicine requires the on-time monitoring of the medical treatment process. This combination of monitoring and therapeutics allows a large degree of control on the treatment efficacy and is now commonly referred to as “theranostics”. Magnetic nanoparticles (NPs) provide a unique nano-platform for theranostic applications due to their comparable sizes with various functional biomolecules, their biocompatibility and their responses to the external magnetic field. Recent efforts in studying magnetic NPs for both imaging and therapeutic applications have led to great advances in NP fabrication with controls in dimension, surface functionalization and magnetic property. These magnetic NPs have been proven to be robust agents that can be target-specific for enhancing magnetic resonance imaging sensitivity and magnetic heating efficiency. These, plus the deep tissue penetration of magnetic field, make magnetic NPs the most promising candidates for successful theranostics in the future. In this Account, we review the recent advances in the synthesis of magnetic NPs of iron oxide, Fe, as well as FePt and FeCo NPs for imaging and therapeutic applications. We will first introduce briefly nanomagnetism, magnetic resonance imaging (MRI), and magnetic fluid hyperthermia (MFH). We will then focus on chemical synthesis of monodisperse magnetic NPs with controlled sizes, morphologies, and magnetic properties. Typical examples in using monodisperse magnetic NPs for MRI and MFH are highlighted. PMID:21661754

Ho, Don; Sun, Xiaolian; Sun, Shouheng

2011-01-01

34

Targeted polymeric magnetic nanoparticles for brain imaging  

NASA Astrophysics Data System (ADS)

The purpose of this study was to develop targeted polymeric magnetic nanoparticle system for brain imaging. Near infrared dye indocyanine green (ICG) or p-gycoprotein substrate rhodamine 123 (Rh123) were encapsulated along with oleic acid coated magnetic nanoparticles (OAMNP) in a matrix of poly(lactide-co-glycolide) (PLGA) and methoxy poly(ethyleneglycol)-poly(lactide) (Met-PEG-PLA). The nanoparticles were evaluated for morphology, particle size, dye content and magnetite content. The in vivo biodistribution study was carried out using three groups of six male Sprague Dawley rats each. Group I received a saline solution containing the dye, group II received dye-loaded polymeric magnetic nanoparticles without the aid of a magnetic field, and group III received dye-loaded polymeric magnetic nanoparticles with a magnet (8000 G) placed on the head of the rat. After a preset exposure period, the animals were sacrificed and dye concentration was measured in the brain, liver, kidney, lungs and spleen homogenates. Brain sections were fixed, cryotomed and visualized using fluorescence microscopy. The particles were observed to be spherical and had a mean size of 220 nm. The encapsulation efficiency for OAMNP was 57%, while that for ICG was 56% and for Rh123 was 45%. In the biodistribution study, while the majority of the dose for all animals was found in the liver, kidneys and spleen, group III showed a significantly higher brain concentration than the other two groups (p < 0.001). This result was corroborated by the fluorescence microscopy studies, which showed enhanced dye penetration into the brain tissue for group III. Further studies need to be done to elucidate the exact mechanism responsible for the increased brain uptake of dye to help us understand if the magnetic nanoparticles actually penetrate the blood brain barrier or merely deliver a massive load of dye just outside it, thereby triggering passive diffusion into the brain parenchyma. These results reinforce the potential use of polymeric magnetically-targeted nanoparticles in active brain targeting and imaging.

Kirthivasan, Bharat; Singh, Dhirender; Raut, Sangram; Bommana, Murali Mohan; Squillante, Emilio, III; Sadoqi, Mostafa

2012-03-01

35

A One-Step Homogeneous Sandwich Immunosensor for Salmonella Detection Based on Magnetic Nanoparticles (MNPs) and Quantum Dots (QDs).  

PubMed

Simple immuno-magnetic separation tandem fluorescent probes based on quantum dots-antibody (QDs-Ab) were developed to detect Salmonella with sensitivity of 500 cfu mL-1. With two monoclonal antibodies, which recognize different antigenic determinant on the surface of Salmonella, we prepared antibody-coated magnetic nanoparticles (MNPs) and conjugates of QDs-Ab. The immune-magnetic beads were verified with high enrichment efficiency for Salmonella (90%). A sandwich structure formed if the Salmonella solution was mixed together with immune-beads and QDs-Ab, and the fluorescent single from QDs was related to the amount of Salmonella. A linear response between fluorescence intensity and various concentrations of Salmonella (2.5 × 103 to 1.95 × 108 cfu mL-1) were observed with this proposed method. The total assay time for Salmonella was 30 min, and no cross-reaction to other microbial strains, such as Staphylococcus aureus, Escherichia coli (E. coli) and Escherichia coli O157:H7 (E. coli O157:H7), were found using this detection system. All our results showed that the simple homogeneous immunoassay could be applied in Salmonella screening without time-consuming extra-enrichment of bacteria. PMID:23609493

Kuang, Hua; Cui, Gang; Chen, Xiujin; Yin, Honghong; Yong, Qianqian; Xu, Liguang; Peng, Chifang; Wang, Libing; Xu, Chuanlai

2013-01-01

36

A One-Step Homogeneous Sandwich Immunosensor for Salmonella Detection Based on Magnetic Nanoparticles (MNPs) and Quantum Dots (QDs)  

PubMed Central

Simple immuno-magnetic separation tandem fluorescent probes based on quantum dots-antibody (QDs-Ab) were developed to detect Salmonella with sensitivity of 500 cfu mL?1. With two monoclonal antibodies, which recognize different antigenic determinant on the surface of Salmonella, we prepared antibody-coated magnetic nanoparticles (MNPs) and conjugates of QDs-Ab. The immune-magnetic beads were verified with high enrichment efficiency for Salmonella (90%). A sandwich structure formed if the Salmonella solution was mixed together with immune-beads and QDs-Ab, and the fluorescent single from QDs was related to the amount of Salmonella. A linear response between fluorescence intensity and various concentrations of Salmonella (2.5 × 103 to 1.95 × 108 cfu mL?1) were observed with this proposed method. The total assay time for Salmonella was 30 min, and no cross-reaction to other microbial strains, such as Staphylococcus aureus, Escherichia coli (E. coli) and Escherichia coli O157:H7 (E. coli O157:H7), were found using this detection system. All our results showed that the simple homogeneous immunoassay could be applied in Salmonella screening without time-consuming extra-enrichment of bacteria. PMID:23609493

Kuang, Hua; Cui, Gang; Chen, Xiujin; Yin, Honghong; Yong, Qianqian; Xu, Liguang; Peng, Chifang; Wang, Libing; Xu, Chuanlai

2013-01-01

37

Terahertz Magnetic Modulator based on Magnetically-Clustered Nanoparticles  

E-print Network

Random orientation of liquid-suspended magnetic nanoparticles (Ferrofluid) gives rise to zero net magnetic orientation. An external magnetic field tends to align them into clusters, leading to a strong linear dichroism on a propagating wave. Using 10 nm-sized Fe3O4, we experimentally realize a polarization-sensitive magnetic modulator operating at terahertz wavelengths. We reached a modulation depth of 66% using a field of 35 mT. The proposed concept offers a solution towards fundamental terahertz magnetic modulators.

Shalaby, Mostafa; Ozturk, Yavuz; Al-Naib, Ibraheem; Hauri, Christoph P; Morandotti, Roberto

2014-01-01

38

Fluorescent Magnetic Nanoparticles for Biomedical Applications  

E-print Network

Fluorescent Magnetic Nanoparticles for Biomedical Applications V.M.Dao, Dr. G. Coullerez, Dr. L absorbed onto the iron oxide surface encapsulated within a silica shell. Four different percentages susceptibility of the cells and by using a calibration curve. HeLa cells incubated with 56 g Fe/ml contained

Candea, George

39

OPTIMIZATION OF A NOVEL MAGNETIC NANOPARTICLE SENSOR  

Microsoft Academic Search

This paper represents an experimental iteration of a novel magnetic nanoparticle (MNP) sensor. MNPs can be used as labels in quantitative diagnostic. Planar microcoils in an impedance bridge are used to measure the amount of the particles. Particles change the inductance of the coil due to their permeability. The shape and size of the coil are critical to the sensitivity

Jarkko Mäkiranta; Jukka Lekkala

40

The preparation of magnetic nanoparticles for applications in biomedicine  

Microsoft Academic Search

This review is focused on describing state-of-the-art synthetic routes for the preparation of magnetic nanoparticles useful for biomedical applications. In addition to this topic, we have also described in some detail some of the possible applications of magnetic nanoparticles in the field of biomedicine with special emphasis on showing the benefits of using nanoparticles. Finally, we have addressed some relevant

Pedro Tartaj; M ar ´ õa del Puerto Morales; Sabino Veintemillas-Verdaguer; Teresita González-Carreño; Carlos J Serna

2003-01-01

41

Simultaneous quantification of multiple magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Distinct magnetic nanoparticle designs can have unique spectral responses to an AC magnetic field in a technique called the magnetic spectroscopy of Brownian motion (MSB). The spectra of the particles have been measured using desktop spectrometers and in vivo measurements. If multiple particle types are present in a region of interest, the unique spectral signatures allow for the simultaneous quantification of the various particles. We demonstrate such a potential experimentally with up to three particle types. This ability to concurrently detect multiple particles will enable new biomedical applications.

Rauwerdink, Adam M.; Giustini, Andrew J.; Weaver, John B.

2010-11-01

42

Arranging matter by magnetic nanoparticle assemblers  

PubMed Central

We introduce a method for transporting colloidal particles, large molecules, cells, and other materials across surfaces and for assembling them into highly regular patterns. In this method, nonmagnetic materials are manipulated by a fluid dispersion of magnetic nanoparticles. Manipulation of materials is guided by a program of magnetic information stored in a substrate. Dynamic control over the motion of nonmagnetic particles can be achieved by reprogramming the substrate magnetization on the fly. The unexpectedly large degree of control over particle motion can be used to manipulate large ensembles of particles in parallel, potentially with local control over particle trajectory. PMID:15956215

Yellen, Benjamin B.; Hovorka, Ondrej; Friedman, Gary

2005-01-01

43

Application of iron magnetic nanoparticles in protein immobilization.  

PubMed

Due to their properties such as superparamagnetism, high surface area, large surface-to-volume ratio, easy separation under external magnetic fields, iron magnetic nanoparticles have attracted much attention in the past few decades. Various modification methods have been developed to produce biocompatible magnetic nanoparticles for protein immobilization. This review provides an updated and integrated focus on the fabrication and characterization of suitable magnetic iron nanoparticle-based nano-active materials for protein immobilization. PMID:25093986

Xu, Jiakun; Sun, Jingjing; Wang, Yuejun; Sheng, Jun; Wang, Fang; Sun, Mi

2014-01-01

44

Magnetic resonance of ferrite nanoparticles  

Microsoft Academic Search

Ferromagnetic resonance (FMR) experiments at 9.26GHz on non-interacting maghemite (?-Fe2O3) nanoparticles of ferrofluids are performed as a function of temperature (3.5–300K) and particle diameter (4.8–10nm). The orientational mobility of the particles inside the fluid is employed to monitor the orientational distribution of the anisotropy axes by solidifying the MF matrix under the external field. On those textured suspensions, angular analysis

F. Gazeau; J. C Bacri; F. Gendron; R. Perzynski; Yu. L Raikher; V. I. Stepanov; E. Dubois

1998-01-01

45

Silver and magnetic nanoparticles for sensitive DNA detection by SERS.  

PubMed

This paper describes the first report of the combination of functionalised silver nanoparticles and silver-coated magnetic nanoparticles in a stable sandwich assay for DNA detection using SERS, providing robust multi-target recognition. PMID:25214257

Donnelly, Tara; Smith, W Ewen; Faulds, Karen; Graham, Duncan

2014-09-30

46

Grafting single molecule magnets on gold nanoparticles.  

PubMed

The chemical synthesis and characterization of the first hybrid material composed by gold nanoparticles and single molecule magnets (SMMs) are described. Gold nanoparticles are functionalized via ligand exchange using a tetrairon(III) SMM containing two 1,2-dithiolane end groups. The grafting is evidenced by the shift of the plasmon resonance peak recorded with a UV-vis spectrometer, by the suppression of nuclear magnetic resonance signals, by X-ray photoemission spectroscopy peaks, and by transmission electron microscopy images. The latter evidence the formation of aggregates of nanoparticles as a consequence of the cross-linking ability of Fe4 through the two 1,2-dithiolane rings located on opposite sides of the metal core. The presence of intact Fe4 molecules is directly proven by synchrotron-based X-ray absorption spectroscopy and X-ray magnetic circular dichroism spectroscopy, while a detailed magnetic characterization, obtained using electron paramagnetic resonance and alternating-current susceptibility, confirms the persistence of SMM behavior in this new hybrid nanostructure. PMID:23996936

Perfetti, Mauro; Pineider, Francesco; Poggini, Lorenzo; Otero, Edwige; Mannini, Matteo; Sorace, Lorenzo; Sangregorio, Claudio; Cornia, Andrea; Sessoli, Roberta

2014-01-29

47

Magnetic and electromagnetic evaluation of the magnetic nanoparticle filled polyurethane nanocomposites  

E-print Network

Magnetic and electromagnetic evaluation of the magnetic nanoparticle filled polyurethane-nanoparticle reinforced polyurethane nanocomposite is reported. Surface-initiated-polymerization SIP method was utilized the absorbing performance. II. EXPERIMENT The polyurethane PU composites reinforced with mag- netic NPs having

Guo, John Zhanhu

48

Photoconjugation of molecularly imprinted polymer with magnetic nanoparticles  

PubMed Central

Because of their synthetic accessibility, molecularly imprinted polymer (MIP) nanoparticles are ideal building blocks for preparing multifunctional composites. In this work we developed a general photo-coupling chemistry to enable simple conjugation of MIP nanoparticles with inorganic magnetic nanoparticles. We first synthesized MIP nanoparticles using propranolol as a model template and perfluorophenylazide-modified silica-coated magnetic nanoparticles. Using a simple photoactivation followed by facile purification with a magnet, we obtained magnetic composite particles that showed selective uptake of propranolol. We characterized the nanoparticles and composite materials using FT-IR, TEM, fluorescence spectroscopy and radioligand binding analysis. Through the high molecular selectivity of the magnetic composite, we demonstrated the non-destructive feature and the high efficiency of the photocoupling chemistry. The versatile photoconjugation method developed in this work should also be very useful for combining organic MIPs with other inorganic nanoparticles to enable new chemical sensors and high efficiency photo-catalysts. PMID:23673293

Xu, Changgang; Uddin, Khan Mohammad Ahsan; Shen, Xiantao; Jayawardena, Surangi; Yan, Mingdi; Ye, Lei

2013-01-01

49

Boosting oncolytic adenovirus potency with magnetic nanoparticles and magnetic force.  

PubMed

Oncolytic adenoviruses rank among the most promising innovative agents in cancer therapy. We examined the potential of boosting the efficacy of the oncolytic adenovirus dl520 by associating it with magnetic nanoparticles and magnetic-field-guided infection in multidrug-resistant (MDR) cancer cells in vitro and upon intratumoral injection in vivo. The virus was complexed by self-assembly with core-shell nanoparticles having a magnetite core of about 10 nm and stabilized by a shell containing 68 mass % lithium 3-[2-(perfluoroalkyl)ethylthio]propionate) and 32 mass % 25 kDa branched polyethylenimine. Optimized virus binding, sufficiently stable in 50% fetal calf serum, was found at nanoparticle-to-virus ratios of 5 fg of Fe per physical virus particle (VP) and above. As estimated from magnetophoretic mobility measurements, 3,600 to 4,500 magnetite nanocrystallites were associated per virus particle. Ultrastructural analysis by electron and atomic force microscopy showed structurally intact viruses surrounded by magnetic particles that occasionally bridged several virus particles. Viral uptake into cells at a given virus dose was enhanced 10-fold compared to nonmagnetic virus when infections were carried out under the influence of a magnetic field. Increased virus internalization resulted in a 10-fold enhancement of the oncolytic potency in terms of the dose required for killing 50% of the target cells (IC(50) value) and an enhancement of 4 orders of magnitude in virus progeny formation at equal input virus doses compared to nonmagnetic viruses. Furthermore, the full oncolytic effect developed within two days postinfection compared with six days in a nonmagnetic virus as a reference. Plotting target cell viability versus internalized virus particles for magnetic and nonmagnetic virus showed that the inherent oncolytic productivity of the virus remained unchanged upon association with magnetic nanoparticles. Hence, we conclude that the mechanism of boosting the oncolytic effect by magnetic force is mainly due to the improved internalization of magnetic virus complexes resulting in potentiated virus progeny formation. Upon intratumoral injection and application of a gradient magnetic field in a murine xenograft model, magnetic virus complexes exhibited a stronger oncolytic effect than adenovirus alone. We propose that this approach would be useful during in vivo administration to tumor-feeding blood vessels to boost the efficacy of the primary infection cycle within the tumor. For systemic application, further modification of magnetic adenovirus complexes for shielding and retargeting of the whole magnetic virus complex entity is needed. PMID:20550160

Tresilwised, Nittaya; Pithayanukul, Pimolpan; Mykhaylyk, Olga; Holm, Per Sonne; Holzmüller, Regina; Anton, Martina; Thalhammer, Stefan; Adigüzel, Denis; Döblinger, Markus; Plank, Christian

2010-08-01

50

Dynamic Hysteresis in Compacted Magnetic Nanoparticles  

NASA Astrophysics Data System (ADS)

The frequency and temperature dependent magnetic response of a bulk soft magnetic nanocomposite made by compacting Fe10Co 90 nanoparticles was measured and modeled. Electron microscopy and x-ray diffraction were used to characterize the size, composition, and structure of the nanoparticles and nanocomposite. Polyol synthesis was used to produce 200 nm particles with average grain size 20 nm and large superparamagnetic fraction. The nanoparticles were consolidated to 90% theoretical density by plasma pressure compaction. The compacted nanoparticles retained the 20 nm average grain size and large superparamagnetic fraction. The nanocomposite resistivity was more than three times that of the bulk alloy. Vibrating sample and SQUID-MPMS magnetometers were used for low frequency magnetic measurements of the nanoparticles and nanocomposite. Compaction reduced the coercivity from 175 Oe to 8 Oe and the effective anisotropy from 124 x 10 3 ergs/cc to 7.9 x 103 ergs/cc. These reductions were caused by increased exchange coupling between surface nanograins, consistent with predictions from the Random Anisotropy model. Varying degrees of exchange coupling existed within the nanocomposite, contributing to a distribution of energy barriers. A permeameter was used for frequency dependent magnetic measurements on a toroid cut from the nanocomposite. Complex permeability, coercivity, and power loss were extracted from dynamic minor hysteresis loops measured over a range of temperatures (77 K - 873 K) and frequencies (0.1 kHz - 100 kHz). The real and imaginary parts of the complex permeability spectrum showed asymmetries consistent with a distribution of energy barriers and high damping. When the complex permeability, power loss, and coercivity were scaled relative to the peak frequency of the imaginary permeability, all fell on universal curves. Various microscopic and macroscopic models for the complex permeability were investigated. The complex permeability was successfully fit by modifying the Cole-Davidson model with a scaling factor that extended the model to higher damping. The additional damping was consistent with the damping from eddy current modeling, showing that the nanocomposite's complex permeability could be explained by combining microscopic effects (the distribution of energy barriers represented by the Cole-Davidson model) with macroscopic effects (damping due to eddy currents).

Chowdary, Krishna M.

51

Facile surface functionalization of hydrophobic magnetic nanoparticles.  

PubMed

Nonpolar phase synthesized hydrophobic nanocrystals show attractive properties and have demonstrated prominent potential in biomedical applications. However, the preparation of biocompatible nanocrystals is made difficult by the presence of hydrophobic surfactant stabilizer on their surfaces. To address this limitation, we have developed a facile, high efficiency, single-phase and low-cost method to convert hydrophobic magnetic nanoparticles (MNPs) to an aqueous phase using tetrahydrofuran, NaOH and 3,4-dihydroxyhydrocinnamic acid without any complicated organic synthesis. The as-transferred hydrophilic MNPs are water-soluble over a wide pH range (pH = 3-12), and the solubility is pH-controllable. Furthermore, the as-transferred MNPs with carboxylate can be readily adapted with further surface functionalization, varying from small molecule dyes to oligonucleotides and enzymes. Finally, the strategy developed here can easily be extended to other types of hydrophobic nanoparticles to facilitate biomedical applications of nanomaterials. PMID:25140614

Liu, Yuan; Chen, Tao; Wu, Cuichen; Qiu, Liping; Hu, Rong; Li, Juan; Cansiz, Sena; Zhang, Liqin; Cui, Cheng; Zhu, Guizhi; You, Mingxu; Zhang, Tao; Tan, Weihong

2014-09-10

52

Inverted Linear Halbach Array for Separation of Magnetic Nanoparticles  

PubMed Central

A linear array of Nd-Fe-B magnets has been designed and constructed in an inverted Halbach configuration for use in separating magnetic nanoparticles. The array provides a large region of relatively low magnetic field, yet high magnetic field gradient in agreement with finite element modeling calculations. The magnet assembly has been combined with a flow channel for magnetic nanoparticle suspensions, such that for an appropriate distance away from the assembly, nanoparticles of higher moment aggregate and accumulate against the channel wall, with lower moment nanoparticles flowing unaffected. The device is demonstrated for iron oxide nanoparticles with diameters of ~ 5 and 20 nm. In comparison to other approaches, the inverted Halbach array is more amenable to modeling and to scaling up to preparative quantities of particles.

Ijiri, Y.; Poudel, C.; Williams, P.S.; Moore, L.R.; Orita, T.; Zborowski, M.

2014-01-01

53

Magnetic nanoparticles for biomedical NMR-based diagnostics  

PubMed Central

Summary Rapid and accurate measurements of protein biomarkers, pathogens and cells in biological samples could provide useful information for early disease diagnosis, treatment monitoring, and design of personalized medicine. In general, biological samples have only negligible magnetic susceptibility. Thus, using magnetic nanoparticles for biosensing not only enhances sensitivity but also effectively reduces sample preparation needs. This review focuses on the use of magnetic nanoparticles for in vitro detection of biomolecules and cells based on magnetic resonance effects. This detection platform, termed diagnostic magnetic resonance (DMR), exploits magnetic nanoparticles as proximity sensors, which modulate the spin–spin relaxation time of water molecules surrounding molecularly-targeted nanoparticles. By developing more effective magnetic nanoparticle biosensors, DMR detection limits for various target moieties have been considerably improved over the last few years. Already, a library of magnetic nanoparticles has been developed, in which a wide range of targets, including DNA/mRNA, proteins, small molecules/drugs, bacteria, and tumor cells, have been quantified. More recently, the capabilities of DMR technology have been further advanced with new developments such as miniaturized nuclear magnetic resonance detectors, better magnetic nanoparticles and novel conjugational methods. These developments have enabled parallel and sensitive measurements to be made from small volume samples. Thus, the DMR technology is a highly attractive platform for portable, low-cost, and efficient biomolecular detection within a biomedical setting. PMID:21977404

Shao, Huilin; Yoon, Tae-Jong; Liong, Monty

2010-01-01

54

TOPICAL REVIEW: Functionalisation of magnetic nanoparticles for applications in biomedicine  

Microsoft Academic Search

Magnetic nanoparticles have been proposed for use as biomedical purposes to a large extent for several years. In recent years, nanotechnology has developed to a stage that makes it possible to produce, characterize and specifically tailor the functional properties of nanoparticles for clinical applications. This has led to various opportunities such as improving the quality of magnetic resonance imaging, hyperthermic

Catherine C. Berry; Adam S. G. Curtis

2003-01-01

55

Magnetic nanoparticles as targeted delivery systems in oncology  

PubMed Central

Background Many different types of nanoparticles, magnetic nanoparticles being just a category among them, offer exciting opportunities for technologies at the interfaces between chemistry, physics and biology. Some magnetic nanoparticles have already been utilized in clinical practice as contrast enhancing agents for magnetic resonance imaging (MRI). However, their physicochemical properties are constantly being improved upon also for other biological applications, such as magnetically-guided delivery systems for different therapeutics. By exposure of magnetic nanoparticles with attached therapeutics to an external magnetic field with appropriate characteristics, they are concentrated and retained at the preferred site which enables the targeted delivery of therapeutics to the desired spot. Conclusions The idea of binding chemotherapeutics to magnetic nanoparticles has been around for 30 years, however, no magnetic nanoparticles as delivery systems have yet been approved for clinical practice. Recently, binding of nucleic acids to magnetic nanoparticles has been demonstrated as a successful non-viral transfection method of different cell lines in vitro. With the optimization of this method called magnetofection, it will hopefully become another form of gene delivery for the treatment of cancer. PMID:22933928

Prijic, Sara; Sersa, Gregor

2011-01-01

56

Magnetic nanoparticles for applications in oscillating magnetic field  

SciTech Connect

Enzymatic and thermochemical catalysis are both important industrial processes. However, the thermal requirements for each process often render them mutually exclusive: thermochemical catalysis requires high temperature that denatures enzymes. One of the long-term goals of this project is to design a thermocatalytic system that could be used with enzymatic systems in situ to catalyze reaction sequences in one pot; this system would be useful for numerous applications e.g. conversion of biomass to biofuel and other commodity products. The desired thermocatalytic system would need to supply enough thermal energy to catalyze thermochemical reactions, while keeping the enzymes from high temperature denaturation. Magnetic nanoparticles are known to generate heat in an oscillating magnetic field through mechanisms including hysteresis and relaxational losses. We envisioned using these magnetic nanoparticles as the local heat source embedded in sub-micron size mesoporous support to spatially separate the particles from the enzymes. In this study, we set out to find the magnetic materials and instrumental conditions that are sufficient for this purpose. Magnetite was chosen as the first model magnetic material in this study because of its high magnetization values, synthetic control over particle size, shape, functionalization and proven biocompatibility. Our experimental designs were guided by a series of theoretical calculations, which provided clues to the effects of particle size, size distribution, magnetic field, frequency and reaction medium. Materials of theoretically optimal size were synthesized, functionalized, and their effects in the oscillating magnetic field were subsequently investigated. Under our conditions, the materials that clustered e.g. silica-coated and PNIPAM-coated iron oxides exhibited the highest heat generation, while iron oxides embedded in MSNs and mesoporous iron oxides exhibited the least bulk heating. It is worth noting that the specific loss power of PNIPAM-coated Fe{sub 3}O{sub 4} was peculiarly high, and the heat loss mechanism of this material remains to be elucidated. Since thermocatalysis is a long-term goal of this project, we also investigated the effects of the oscillating magnetic field system for the synthesis of 7-hydroxycoumarin-3-carboxylic acid. Application of an oscillating magnetic field in the presence of magnetic particles with high thermal response was found to effectively increase the reaction rate of the uncatalyzed synthesis of the coumarin derivative compared to the room temperature control.

Peeraphatdit, Chorthip

2010-12-15

57

Local Control of Ultrafast Dynamics of Magnetic Nanoparticles  

SciTech Connect

Using the local control theory we derive analytical expressions for magnetic field pulses that steer the magnetization of a monodomain magnetic nanoparticle to a predefined state. Finite-temperature full numerical simulations confirm the analytical results and show that a magnetization switching or freezing is achievable within few precessional periods and that the scheme is exploitable for fast thermal switching.

Sukhov, A. [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, D-06120 Halle/Saale (Germany); Institut fuer Physik, Martin-Luther-Universitaet Halle-Wittenberg, Heinrich-Damerow-Str. 4, 06120 Halle (Germany); Berakdar, J. [Institut fuer Physik, Martin-Luther-Universitaet Halle-Wittenberg, Heinrich-Damerow-Str. 4, 06120 Halle (Germany)

2009-02-06

58

TOPICAL REVIEW: Applications of magnetic nanoparticles in biomedicine  

Microsoft Academic Search

The physical principles underlying some current biomedical applications of magnetic nanoparticles are reviewed. Starting from well-known basic concepts, and drawing on examples from biology and biomedicine, the relevant physics of magnetic materials and their responses to applied magnetic fields are surveyed. The way these properties are controlled and used is illustrated with reference to (i) magnetic separation of labelled cells

Q. A. Pankhurst; J. Connolly; S. K. Jones; J. Dobson

2003-01-01

59

Quantitative measurement of the magnetic moment of individual magnetic nanoparticles by magnetic force microscopy.  

PubMed

The quantitative measurement of the magnetization of individual magnetic nanoparticles (MNPs) using magnetic force microscopy (MFM) is described. Quantitative measurement is realized by calibration of the MFM signal using an MNP reference sample with traceably determined magnetization. A resolution of the magnetic moment of the order of 10(-18) A m(2) under ambient conditions is demonstrated, which is presently limited by the tip's magnetic moment and the noise level of the instrument. The calibration scheme can be applied to practically any magnetic force microscope and tip, thus allowing a wide range of future applications, for example in nanomagnetism and biotechnology. PMID:22730177

Sievers, Sibylle; Braun, Kai-Felix; Eberbeck, Dietmar; Gustafsson, Stefan; Olsson, Eva; Schumacher, Hans Werner; Siegner, Uwe

2012-09-10

60

Quantitative Measurement of the Magnetic Moment of Individual Magnetic Nanoparticles by Magnetic Force Microscopy  

PubMed Central

The quantitative measurement of the magnetization of individual magnetic nanoparticles (MNPs) using magnetic force microscopy (MFM) is described. Quantitative measurement is realized by calibration of the MFM signal using an MNP reference sample with traceably determined magnetization. A resolution of the magnetic moment of the order of 10?18 A m2 under ambient conditions is demonstrated, which is presently limited by the tip's magnetic moment and the noise level of the instrument. The calibration scheme can be applied to practically any magnetic force microscope and tip, thus allowing a wide range of future applications, for example in nanomagnetism and biotechnology. PMID:22730177

Sievers, Sibylle; Braun, Kai-Felix; Eberbeck, Dietmar; Gustafsson, Stefan; Olsson, Eva; Schumacher, Hans Werner; Siegner, Uwe

2012-01-01

61

Magnetic properties of Mg-ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

MgFe 2O 4 nanoparticles encapsulated in amorphous SiO 2 were prepared by means of a wet chemical method, and the magnetic properties were studied. The diameters of these particles were estimated from X-ray diffraction patterns as ranging from 3 to 8 nm. Magnetization measurements were carried out for each sample under a ±50 kOe field. The blocking temperature, Tb, was determined to be around 30 K from the temperature dependence of both the field-cooled (FC) and the zero-field-cooled (ZFC) magnetization. The M- H curve indicated the presence of ferromagnetic behavior with hysteresis below the blocking temperature, Tb. A large coercive force of about 1000 Oe was found at 5 K. Heat treatment was carried out for the prepared samples using an electric furnace in air. A clear difference in magnetization was found between the quenched samples and annealed samples. This phenomenon suggests that the Mg 2+ ions in the spinel structure would be randomly distributed into both the A- and the B-site.

Ichiyanagi, Y.; Kubota, M.; Moritake, S.; Kanazawa, Y.; Yamada, T.; Uehashi, T.

2007-03-01

62

Calculation of nanoparticle capture efficiency in magnetic drug targeting  

Microsoft Academic Search

The implant assisted magnetic targeted drug delivery system of Avilés, Ebner and Ritter, which uses high gradient magnetic separation (HGMS) is considered. In this 2D model large ferromagnetic particles are implanted as seeds to aid collection of multiple domain nanoparticles (radius ?200nm). Here, in contrast, single domain magnetic nanoparticles (radius in 20–100nm) are considered and the Langevin function is used

P. J. Cregg; Kieran Murphy; Adil Mardinoglu

2008-01-01

63

Oil-field wastewater purification by magnetic separation technique using a novel magnetic nanoparticle  

NASA Astrophysics Data System (ADS)

In the present work, oil-field wastewater purification through superconducting magnetic separation technique using a novel magnetic nanoparticle was investigated. The magnetic nanoparticle, which has a multi-shell structure with ferroferric oxide as core, dense nonporous silica as inter layer and mesoporous silica as outer layer, was synthesized by co-precipitation method. To functionalize the magnetic nanoparticle, plasma polymerization technique was adopted and poly methyl acrylate (PMA) was formed on the surface of the nanoparticle. The multi-shell structure of the nanoparticle was confirmed by transmission electron microscope (TEM) and the characteristic is measurable by FTIR. It is found that most of the pollutants (85% by turbidity or 84% by COD value) in the oil-field wastewater are removed through the superconducting magnetic separation technique using this novel magnetic nanoparticle.

Liu, Zhuonan; Yang, Huihui; Zhang, Hao; Huang, Chuanjun; Li, Laifeng

2012-12-01

64

Magnetically Responsive Nanoparticles for Drug Delivery Applications Using Low Magnetic Field Strengths  

Microsoft Academic Search

The purpose of this study is to investigate the potential of magnetic nanoparticles for enhancing drug delivery using a low oscillating magnetic field (OMF) strength. We investigated the ability of magnetic nanoparticles to cause disruption of a viscous biopolymer barrier to drug delivery and the potential to induce triggered release of drug conjugated to the surfaces of these particles. Various

Shayna L. McGill; Carla L. Cuylear; Natalie L. Adolphi; M. Osinski; Hugh D. C. Smyth

2009-01-01

65

Kinetics and pathogenesis of intracellular magnetic nanoparticle cytotoxicity  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles excited by alternating magnetic fields (AMF) have demonstrated effective tumor-specific hyperthermia. This treatment is effective as a monotherapy as well as a therapeutic adjuvant to chemotherapy and radiation. Iron oxide nanoparticles have been shown, so far, to be non-toxic, as are the exciting AMF fields when used at moderate levels. Although higher levels of AMF can be more effective, depending on the type of iron oxide nanoparticles use, these higher field strengths and/or frequencies can induce normal tissue heating and toxicity. Thus, the use of nanoparticles exhibiting significant heating at low AMF strengths and frequencies is desirable. Our preliminary experiments have shown that the aggregation of magnetic nanoparticles within tumor cells improves their heating effect and cytotoxicity per nanoparticle. We have used transmission electron microscopy to track the endocytosis of nanoparticles into tumor cells (both breast adenocarcinoma (MTG-B) and acute monocytic leukemia (THP-1) cells). Our preliminary results suggest that nanoparticles internalized into tumor cells demonstrate greater cytotoxicity when excited with AMF than an equivalent heat dose from excited external nanoparticles or cells exposed to a hot water bath. We have also demonstrated that this increase in SAR caused by aggregation improves the cytotoxicity of nanoparticle hyperthermia therapy in vitro.

Giustini, Andrew J.; Gottesman, Rachel E.; Petryk, A. A.; Rauwerdink, A. M.; Hoopes, P. Jack

2011-03-01

66

Magnetic nanoparticles: synthesis, functionalization, and applications in bioimaging and magnetic energy storage  

PubMed Central

This tutorial review summarizes the recent advances in the chemical synthesis and potential applications of monodisperse magnetic nanoparticles. After a brief introduction to nanomagnetism, the review focuses on recent developments in solution phase syntheses of monodisperse MFe2O4, Co, Fe, CoFe, FePt and SmCo5 nanoparticles. The review further outlines the surface, structural, and magnetic properties of these nanoparticles for biomedicine and magnetic energy storage applications. PMID:19690734

Frey, Natalie A.; Peng, Sheng; Cheng, Kai; Sun, Shouheng

2009-01-01

67

Magnetic nanoparticles: synthesis, functionalization, and applications in bioimaging and magnetic energy storage.  

PubMed

This tutorial review summarizes the recent advances in the chemical synthesis and potential applications of monodisperse magnetic nanoparticles. After a brief introduction to nanomagnetism, the review focuses on recent developments in solution phase syntheses of monodisperse MFe(2)O(4), Co, Fe, CoFe, FePt and SmCo(5) nanoparticles. The review further outlines the surface, structural, and magnetic properties of these nanoparticles for biomedicine and magnetic energy storage applications. PMID:19690734

Frey, Natalie A; Peng, Sheng; Cheng, Kai; Sun, Shouheng

2009-09-01

68

Electronic and magnetic properties of MnAu nanoparticles  

NASA Astrophysics Data System (ADS)

Self-consistent ab initio calculations, based on DFT (Density Functional Theory) approach and using FLAPW (Full potential Linear Augmented Plane Wave) method, are performed to investigate both electronic and magnetic properties of the MnAu nanoparticles. Polarized spin is included in calculations within the framework of the antiferromagnetic. The Mn magnetic moments where considered to be along c axes. Obtained data from ab initio calculations are used as input for the high temperature series expansions (HTSEs) calculations to compute other magnetic parameters. The zero-field high temperature static susceptibility series of the magnetic moment (m) and nearest-neighbour Heisenberg and XY models on a MnAu nanoparticles is thoroughly analyzed by means of a power series coherent anomaly method (CAM) for different nanoparticles. The exchanges interactions between the magnetic atoms are obtained for MnAu nanoparticles.

Masrour, R.; Hlil, E. K.; Hamedoun, M.; Benyoussef, A.; Mounkachi, O.; El moussaoui, H.

2014-03-01

69

Advanced magnetic anisotropy determination through isothermal remanent magnetization of nanoparticles  

NASA Astrophysics Data System (ADS)

We propose a theoretical framework enabling the simulation of isothermal remanence magnetization (IRM) curves, based on the Stoner-Wohlfarth model combined with the Néel macrospin relaxation time description. We show how low temperature IRM curves, which have many advantages compared to hysteresis loops, can be efficiently computed for realistic assemblies of magnetic particles with both a size and anisotropy constant distribution, and a biaxial anisotropy. The IRM curves, which probe the irreversible switching provoked by an applied field, are shown to be complementary to other usual measurements (in particular low-field susceptibility curves where a thermal switching is involved). As an application, the experimental IRM curve of Co clusters embedded in a carbon matrix is analyzed. We demonstrate how powerful such an analysis can be, which in the present case allows us to put into evidence an anisotropy constant dispersion among the Co nanoparticles.

Hillion, A.; Tamion, A.; Tournus, F.; Gaier, O.; Bonet, E.; Albin, C.; Dupuis, V.

2013-09-01

70

Magnetic properties of superparamagnetic nanoparticles loaded into silicon nanotubes  

NASA Astrophysics Data System (ADS)

In this work, the magnetic properties of silicon nanotubes (SiNTs) filled with Fe3O4 nanoparticles (NPs) are investigated. SiNTs with different wall thicknesses of 10 and 70 nm and an inner diameter of approximately 50 nm are prepared and filled with superparamagnetic iron oxide nanoparticles of 4 and 10 nm in diameter. The infiltration process of the NPs into the tubes and dependence on the wall-thickness is described. Furthermore, data from magnetization measurements of the nanocomposite systems are analyzed in terms of iron oxide nanoparticle size dependence. Such biocompatible nanocomposites have potential merit in the field of magnetically guided drug delivery vehicles.

Granitzer, Petra; Rumpf, Klemens; Gonzalez, Roberto; Coffer, Jeffery; Reissner, Michael

2014-08-01

71

Inhalable magnetic nanoparticles for targeted hyperthermia in lung cancer therapy.  

PubMed

Lung cancer (specifically, non-small cell lung cancer; NSCLC) is the leading cause of cancer-related deaths in the United States. Poor response rates and survival with current treatments clearly indicate the urgent need for developing an effective means to treat NSCLC. Magnetic hyperthermia is a non-invasive approach for tumor ablation, and is based on heat generation by magnetic materials, such as superparamagnetic iron oxide (SPIO) nanoparticles, when subjected to an alternating magnetic field. However, inadequate delivery of magnetic nanoparticles to tumor cells can result in sub-lethal temperature change and induce resistance while non-targeted delivery of these particles to the healthy tissues can result in toxicity. In our studies, we evaluated the effectiveness of tumor-targeted SPIO nanoparticles for magnetic hyperthermia of lung cancer. EGFR-targeted, inhalable SPIO nanoparticles were synthesized and characterized for targeting lung tumor cells as well as for magnetic hyperthermia-mediated antitumor efficacy in a mouse orthotopic model of NSCLC. Our results show that EGFR targeting enhances tumor retention of SPIO nanoparticles. Further, magnetic hyperthermia treatment using targeted SPIO nanoparticles resulted in significant inhibition of in vivo lung tumor growth. Overall, this work demonstrates the potential for developing an effective anticancer treatment modality for the treatment of NSCLC based on targeted magnetic hyperthermia. PMID:23591395

Sadhukha, Tanmoy; Wiedmann, Timothy S; Panyam, Jayanth

2013-07-01

72

Bacterially synthesized ferrite nanoparticles for magnetic hyperthermia applications.  

PubMed

Magnetic hyperthermia uses AC stimulation of magnetic nanoparticles to generate heat for cancer cell destruction. Whilst nanoparticles produced inside magnetotactic bacteria have shown amongst the highest reported heating to date, these particles are magnetically blocked so that strong heating occurs only for mobile particles, unless magnetic field parameters are far outside clinical limits. Here, nanoparticles extracellularly produced by the bacteria Geobacter sulfurreducens are investigated that contain Co or Zn dopants to tune the magnetic anisotropy, saturation magnetization and nanoparticle sizes, enabling heating within clinical field constraints. The heating mechanisms specific to either Co or Zn doping are determined from frequency dependent specific absorption rate (SAR) measurements and innovative AC susceptometry simulations that use a realistic model concerning clusters of polydisperse nanoparticles in suspension. Whilst both particle types undergo magnetization relaxation and show heating effects in water under low AC frequency and field, only Zn doped particles maintain relaxation combined with hysteresis losses even when immobilized. This magnetic heating process could prove important in the biological environment where nanoparticle mobility may not be possible. Obtained SARs are discussed regarding clinical conditions which, together with their enhanced MRI contrast, indicate that biogenic Zn doped particles are promising for combined diagnostics and cancer therapy. PMID:25232657

Céspedes, Eva; Byrne, James M; Farrow, Neil; Moise, Sandhya; Coker, Victoria S; Bencsik, Martin; Lloyd, Jonathan R; Telling, Neil D

2014-10-01

73

Synthesis and characterization of noscapine loaded magnetic polymeric nanoparticles  

Microsoft Academic Search

The delivery of noscapine therapies directly to the site of the tumor would ultimately allow higher concentrations of the drug to be delivered, and prolong circulation time in vivo to enhance the therapeutic outcome of this drug. Therefore, we sought to design magnetic based polymeric nanoparticles for the site directed delivery of noscapine to invasive tumors. We synthesized Fe3O4 nanoparticles

Mohamed O. Abdalla; Ritu Aneja; Derrick Dean; Vijay Rangari; Albert Russell; Jessie Jaynes; Clayton Yates; Timothy Turner

2010-01-01

74

The Influence of Temperature on the Magnetic Behavior of Colloidal Cobalt Nanoparticles  

Microsoft Academic Search

Applications of magnetic nanoparticles, including hyperthermia for cancer treatments, require knowledge of how the colloidal environment affects the magnetic properties of the nanoparticles. Here, 10 nm diameter cobalt nanoparticles synthesized by thermodecomposition in 1,2-dichlorobenzene (DCB) are used to study the effect of the colloidal environment on the magnetic behavior of such materials. The magnetic properties are investigated by magnetization (M)

C. L. Dennis; G. Cheng; K. A. Baler; B. B. Maranville; A. R. Hight Walker; R. D. Shull

2007-01-01

75

Ionic magnetic fluid based on cobalt ferrite nanoparticles: Influence of hydrothermal treatment on the nanoparticle size  

Microsoft Academic Search

Magnetic fluid based on cobalt ferrite nanoparticles was obtained using a hydrothermal treatment added to the Massart procedure. This treatment increases the average size of the nanoparticles from 11.9 to 18.7nm and also improves the dispersity and crystallinity of the cobalt ferrite particles. The nanoparticles obtained after the hydrothermal treatment were dispersed in aqueous solvent by the classical procedure for

Valérie Cabuil; Vincent Dupuis; Delphine Talbot; Sophie Neveu

2011-01-01

76

Optimizing hysteretic power loss of magnetic ferrite nanoparticles  

E-print Network

This thesis seeks to correlate hysteretic power loss of tertiary ferrite nanoparticles in alternating magnetic fields to trends predicted by physical models. By employing integration of hysteresis loops simulated from ...

Chen, Ritchie

2013-01-01

77

Temperature of the magnetic nanoparticle microenvironment: estimation from relaxation times.  

PubMed

Accurate temperature measurements are essential to safe and effective thermal therapies for cancer and other diseases. However, conventional thermometry is challenging so using the heating agents themselves as probes allows for ideal local measurements. Here, we present a new noninvasive method for measuring the temperature of the microenvironment surrounding magnetic nanoparticles from the Brownian relaxation time of nanoparticles. Experimentally, the relaxation time can be determined from the nanoparticle magnetization induced by an alternating magnetic field at various applied frequencies. A previously described method for nanoparticle temperature estimation used a low frequency Langevin function description of magnetic dipoles and varied the excitation field amplitude to estimate the energy state distribution and the corresponding temperature. We show that the new method is more accurate than the previous method at higher applied field frequencies that push the system farther from equilibrium. PMID:24556943

Perreard, I M; Reeves, D B; Zhang, X; Kuehlert, E; Forauer, E R; Weaver, J B

2014-03-01

78

Magnetic nanoparticle-supported glutathione: a conceptually sustainable organocatalyst  

EPA Science Inventory

A conceptually novel nanoparticle-supported and magnetically recoverable organocatalyst has been developed, which is readily prepared from inexpensive starting materials in a truly sustainable manner; which catalyzes Paal-Knorr reaction with high yield in pure aqueous medium that...

79

Magnetic Nanoparticles for Multi-Imaging and Drug Delivery  

PubMed Central

Various bio-medical applications of magnetic nanoparticles have been explored during the past few decades. As tools that hold great potential for advancing biological sciences, magnetic nanoparticles have been used as platform materials for enhanced magnetic resonance imaging (MRI) agents, biological separation and magnetic drug delivery systems, and magnetic hyperthermia treatment. Furthermore, approaches that integrate various imaging and bioactive moieties have been used in the design of multi-modality systems, which possess synergistically enhanced properties such as better imaging resolution and sensitivity, molecular recognition capabilities, stimulus responsive drug delivery with on-demand control, and spatio-temporally controlled cell signal activation. Below, recent studies that focus on the design and synthesis of multi-mode magnetic nanoparticles will be briefly reviewed and their potential applications in the imaging and therapy areas will be also discussed. PMID:23579479

Lee, Jae-Hyun; Kim, Ji-wook; Cheon, Jinwoo

2013-01-01

80

Magnetic nanoparticles for multi-imaging and drug delivery.  

PubMed

Various bio-medical applications of magnetic nanoparticles have been explored during the past few decades. As tools that hold great potential for advancing biological sciences, magnetic nanoparticles have been used as platform materials for enhanced magnetic resonance imaging (MRI) agents, biological separation and magnetic drug delivery systems, and magnetic hyperthermia treatment. Furthermore, approaches that integrate various imaging and bioactive moieties have been used in the design of multi-modality systems, which possess synergistically enhanced properties such as better imaging resolution and sensitivity, molecular recognition capabilities, stimulus responsive drug delivery with on-demand control, and spatio-temporally controlled cell signal activation. Below, recent studies that focus on the design and synthesis of multi-mode magnetic nanoparticles will be briefly reviewed and their potential applications in the imaging and therapy areas will be also discussed. PMID:23579479

Lee, Jae-Hyun; Kim, Ji-Wook; Cheon, Jinwoo

2013-04-01

81

Magnetic nanoparticle-based hyperthermia for cancer treatment  

PubMed Central

Nanotechnology involves the study of nature at a very small scale, searching new properties and applications. The development of this area of knowledge affects greatly both biotechnology and medicine disciplines. The use of materials at the nanoscale, in particular magnetic nanoparticles, is currently a prominent topic in healthcare and life science. Due to their size-tunable physical and chemical properties, magnetic nanoparticles have demonstrated a wide range of applications ranging from medical diagnosis to treatment. Combining a high saturation magnetization with a properly functionalized surface, magnetic nanoparticles are provided with enhanced functionality that allows them to selectively attach to target cells or tissues and play their therapeutic role in them. In particular, iron oxide nanoparticles are being actively investigated to achieve highly efficient carcinogenic cell destruction through magnetic hyperthermia treatments. Hyperthermia in different approaches has been used combined with radiotherapy during the last decades, however, serious harmful secondary effects have been found in healthy tissues to be associated with these treatments. In this framework, nanotechnology provides a novel and original solution with magnetic hyperthermia, which is based on the use of magnetic nanoparticles to remotely induce local heat when a radiofrequency magnetic field is applied, provoking a temperature increase in those tissues and organs where the tumoral cells are present. Therefore, one important factor that determines the efficiency of this technique is the ability of magnetic nanoparticles to be driven and accumulated in the desired area inside the body. With this aim, magnetic nanoparticles must be strategically surface functionalized to selectively target the injured cells and tissues. PMID:24416585

Bañobre-López, Manuel; Teijeiro, Antonio; Rivas, Jose

2013-01-01

82

Bacterially synthesized ferrite nanoparticles for magnetic hyperthermia applications  

NASA Astrophysics Data System (ADS)

Magnetic hyperthermia uses AC stimulation of magnetic nanoparticles to generate heat for cancer cell destruction. Whilst nanoparticles produced inside magnetotactic bacteria have shown amongst the highest reported heating to date, these particles are magnetically blocked so that strong heating occurs only for mobile particles, unless magnetic field parameters are far outside clinical limits. Here, nanoparticles extracellularly produced by the bacteria Geobacter sulfurreducens are investigated that contain Co or Zn dopants to tune the magnetic anisotropy, saturation magnetization and nanoparticle sizes, enabling heating within clinical field constraints. The heating mechanisms specific to either Co or Zn doping are determined from frequency dependent specific absorption rate (SAR) measurements and innovative AC susceptometry simulations that use a realistic model concerning clusters of polydisperse nanoparticles in suspension. Whilst both particle types undergo magnetization relaxation and show heating effects in water under low AC frequency and field, only Zn doped particles maintain relaxation combined with hysteresis losses even when immobilized. This magnetic heating process could prove important in the biological environment where nanoparticle mobility may not be possible. Obtained SARs are discussed regarding clinical conditions which, together with their enhanced MRI contrast, indicate that biogenic Zn doped particles are promising for combined diagnostics and cancer therapy.Magnetic hyperthermia uses AC stimulation of magnetic nanoparticles to generate heat for cancer cell destruction. Whilst nanoparticles produced inside magnetotactic bacteria have shown amongst the highest reported heating to date, these particles are magnetically blocked so that strong heating occurs only for mobile particles, unless magnetic field parameters are far outside clinical limits. Here, nanoparticles extracellularly produced by the bacteria Geobacter sulfurreducens are investigated that contain Co or Zn dopants to tune the magnetic anisotropy, saturation magnetization and nanoparticle sizes, enabling heating within clinical field constraints. The heating mechanisms specific to either Co or Zn doping are determined from frequency dependent specific absorption rate (SAR) measurements and innovative AC susceptometry simulations that use a realistic model concerning clusters of polydisperse nanoparticles in suspension. Whilst both particle types undergo magnetization relaxation and show heating effects in water under low AC frequency and field, only Zn doped particles maintain relaxation combined with hysteresis losses even when immobilized. This magnetic heating process could prove important in the biological environment where nanoparticle mobility may not be possible. Obtained SARs are discussed regarding clinical conditions which, together with their enhanced MRI contrast, indicate that biogenic Zn doped particles are promising for combined diagnostics and cancer therapy. Electronic supplementary information (ESI) available: Further details of the cluster model of polydisperse nanoparticles used for the AC susceptibility simulations (Fig. S1 to S3). Examples of the heating curves and the linear fit used to determine the SAR values are shown in Fig. S4. Fig. S5 exhibits the energy loss per mass of iron during magnetic hyperthermia (from SAR values) normalized to H2 and frequency for further comparison among samples. Fig. S6 shows the comparison between the simulations of AC susceptibility spectra including regions below and above the experimental frequency range for MNA, Zn0.2 and Zn0.4 nanoparticles suspended in solvents with different viscosities (water, glycerol and a hypothetical high viscous solvent). Fig. S7 exhibits a comparison among the simulated ?'' susceptibility of MNA, Zn0.2 and Zn0.4 nanoparticles (a) in water and (b) in glycerol. See DOI: 10.1039/c4nr03004d

Céspedes, Eva; Byrne, James M.; Farrow, Neil; Moise, Sandhya; Coker, Victoria S.; Bencsik, Martin; Lloyd, Jonathan R.; Telling, Neil D.

2014-10-01

83

Application of magnetic nanoparticle for controlled tissue assembly and tissue engineering.  

PubMed

Magnetic nanoparticles have been subjected to extensive studies in the past few decades owing to their promising potentials in biomedical applications. The versatile intrinsic properties of magnetic nanoparticles enable their use in many biomedical applications. Recently, magnetic nanoparticles were utilized to control the cell's function. In addition, intracellular delivery of magnetic nanoparticles allowed cell's positioning by appropriate use of magnetic field and created cellular cluster. Furthermore, magnetic nanoparticles have been utilized to assemble more complex tissue structures than those that are achieved by conventional scaffold-based tissue engineering strategies. This review addresses recent work in the use magnetic nanoparticle for controlled tissue assembly and complex tissue formation. PMID:24310100

Lee, Eunjee A; Yim, Hyungu; Heo, Jiseung; Kim, Hwan; Jung, Giyoung; Hwang, Nathaniel S

2014-01-01

84

Differential magnetic catch and release: experimental parameters for controlled separation of magnetic nanoparticles.  

PubMed

Differential magnetic catch and release (DMCR) has been used as a method for the purification and separation of magnetic nanoparticles. DMCR separates nanoparticles in the mobile phase by magnetic trapping of magnetic nanoparticles against the wall of an open tubular capillary wrapped between two narrowly spaced electromagnetic poles. Using Au and CoFe(2)O(4) nanoparticles as model systems, the loading capacity of the 250 ?m diameter capillary is determined to be ?130 ?g, and is scalable to higher quantities with larger bore capillary. Peak resolution in DMCR is externally controlled by selection of the release time (R(t)) at which the magnetic flux density is removed, however, longer capture times are shown to reduce the capture yield. In addition, the magnetic nanoparticle capture yields are observed to depend on the nanoparticle diameter, mobile phase viscosity and velocity, and applied magnetic flux. Using these optimized parameters, three samples of CoFe(2)O(4) nanoparticles whose diameters are different by less than 10 nm are separated with excellent resolution and capture yield, demonstrating the capability of DMCR for separation and purification of magnetic nanoparticles. PMID:21562675

Beveridge, Jacob S; Stephens, Jason R; Williams, Mary Elizabeth

2011-06-21

85

Design of superparamagnetic nanoparticles for magnetic particle imaging (MPI).  

PubMed

Magnetic particle imaging (MPI) is a promising medical imaging technique producing quantitative images of the distribution of tracer materials (superparamagnetic nanoparticles) without interference from the anatomical background of the imaging objects (either phantoms or lab animals). Theoretically, the MPI platform can image with relatively high temporal and spatial resolution and sensitivity. In practice, the quality of the MPI images hinges on both the applied magnetic field and the properties of the tracer nanoparticles. Langevin theory can model the performance of superparamagnetic nanoparticles and predict the crucial influence of nanoparticle core size on the MPI signal. In addition, the core size distribution, anisotropy of the magnetic core and surface modification of the superparamagnetic nanoparticles also determine the spatial resolution and sensitivity of the MPI images. As a result, through rational design of superparamagnetic nanoparticles, the performance of MPI could be effectively optimized. In this review, the performance of superparamagnetic nanoparticles in MPI is investigated. Rational synthesis and modification of superparamagnetic nanoparticles are discussed and summarized. The potential medical application areas for MPI, including cardiovascular system, oncology, stem cell tracking and immune related imaging are also analyzed and forecasted. PMID:24030719

Du, Yimeng; Lai, Pui To; Leung, Cheung Hoi; Pong, Philip W T

2013-01-01

86

Design of Superparamagnetic Nanoparticles for Magnetic Particle Imaging (MPI)  

PubMed Central

Magnetic particle imaging (MPI) is a promising medical imaging technique producing quantitative images of the distribution of tracer materials (superparamagnetic nanoparticles) without interference from the anatomical background of the imaging objects (either phantoms or lab animals). Theoretically, the MPI platform can image with relatively high temporal and spatial resolution and sensitivity. In practice, the quality of the MPI images hinges on both the applied magnetic field and the properties of the tracer nanoparticles. Langevin theory can model the performance of superparamagnetic nanoparticles and predict the crucial influence of nanoparticle core size on the MPI signal. In addition, the core size distribution, anisotropy of the magnetic core and surface modification of the superparamagnetic nanoparticles also determine the spatial resolution and sensitivity of the MPI images. As a result, through rational design of superparamagnetic nanoparticles, the performance of MPI could be effectively optimized. In this review, the performance of superparamagnetic nanoparticles in MPI is investigated. Rational synthesis and modification of superparamagnetic nanoparticles are discussed and summarized. The potential medical application areas for MPI, including cardiovascular system, oncology, stem cell tracking and immune related imaging are also analyzed and forecasted. PMID:24030719

Du, Yimeng; Lai, Pui To; Leung, Cheung Hoi; Pong, Philip W. T.

2013-01-01

87

Quantifying magnetic nanoparticles in non-steady flow by MRI  

Microsoft Academic Search

Objective  This work compares the measured $${{R}_{2}^*}$$ of magnetic nanoparticles to their corresponding theoretical values in both gel phantoms and dynamic water flows on the basis\\u000a of the static dephasing theory.\\u000a \\u000a \\u000a \\u000a Materials and methods  The magnetic moment of a nanoparticle solution was measured by a magnetometer. The $${{R}_{2}^*}$$ of the nanoparticle solution doped in a gel phantom was measured at both 1.5

Yimin Shen; Yu-Chung N. Cheng; Gavin Lawes; Jaladhar Neelavalli; Chandran Sudakar; Ronald Tackett; Hari P. Ramnath; E. Mark Haacke

2008-01-01

88

Soft magnets from the self-organization of magnetic nanoparticles in twisted liquid crystals.  

PubMed

Organizing magnetic nanoparticles into long-range and dynamic assemblies would not only provide new insights into physical phenomena but also open opportunities for a wide spectrum of applications. In particular, a major challenge consists of the development of nanoparticle-based materials for which the remnant magnetization and coercive field can be controlled at room temperature. Our approach consists of promoting the self-organization of magnetic nanoparticles in liquid crystals (LCs). Using liquid crystals as organizing templates allows us to envision the design of tunable self-assemblies of magnetic nanoparticles, because liquid crystals are known to reorganize under a variety of external stimuli. Herein, we show that twisted liquid crystals can be used as efficient anisotropic templates for superparamagnetic nanoparticles and demonstrate the formation of hybrid soft magnets at room temperature. PMID:25196652

Matt, Benjamin; Pondman, Kirsten M; Asshoff, Sarah J; Ten Haken, Bennie; Fleury, Benoit; Katsonis, Nathalie

2014-11-10

89

Fluorescent Magnetic Nanoparticles for Magnetically Enhanced Cancer Imaging and Targeting in Living Subjects  

PubMed Central

Early detection and targeted therapy are two major challenges in the battle against cancer. Novel imaging contrast agents and targeting approaches are greatly needed to improve the sensitivity and specificity of cancer theranostic agents. Here, we implemented a novel approach using a magnetic micromesh and biocompatible fluorescent magnetic nanoparticles (FMN) to magnetically enhance cancer targeting in living subjects. This approach enables magnetic targeting of systemically administered individual FMN, containing a single 8 nm superparamagnetic iron oxide (SPIO) core. Using a human glioblastoma mouse model, we show that nanoparticles can be magnetically retained in both the tumor neovasculature and surrounding tumor tissues. Magnetic accumulation of nanoparticles within the neovasculature was observable by fluorescence intravital microscopy in real time. Finally, we demonstrate that such magnetically enhanced cancer targeting augments the biological functions of molecules linked to the nanoparticle surface. PMID:22857784

Fu, Aihua; Wilson, Robert J.; Smith, Bryan R.; Mullenix, Joyce; Earhart, Chris; Akin, Demir; Guccione, Samira; Wang, Shan X.; Gambhir, Sanjiv S.

2013-01-01

90

A direct competitive enzyme-linked immunosorbent assay by antibody coated for diethyl phthalate analysis  

Microsoft Academic Search

A direct competitive enzyme-linked immunosorbent assay (ELISA) has been developed for detection of diethyl phthalate (DEP). Protein–hapten conjugate was synthesized to produce polyclonal antibodies against DEP. Experimental parameters were optimized, including immunoreaction conditions, the dilution ratio of horseradish peroxidase (HRP)–antigen conjugate, time of the antibody coated, effect of pH, and ionic strength. The limit of detection was 0.096ng\\/ml, and the

Mingcui Zhang; Ying Cong; Yali Sheng; Bolin Liu

2010-01-01

91

Spatiotemporal control of microtubule nucleation and assembly using magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Decisions on the fate of cells and their functions are dictated by the spatiotemporal dynamics of molecular signalling networks. However, techniques to examine the dynamics of these intracellular processes remain limited. Here, we show that magnetic nanoparticles conjugated with key regulatory proteins can artificially control, in time and space, the Ran/RCC1 signalling pathway that regulates the cell cytoskeleton. In the presence of a magnetic field, RanGTP proteins conjugated to superparamagnetic nanoparticles can induce microtubule fibres to assemble into asymmetric arrays of polarized fibres in Xenopus laevis egg extracts. The orientation of the fibres is dictated by the direction of the magnetic force. When we locally concentrated nanoparticles conjugated with the upstream guanine nucleotide exchange factor RCC1, the assembly of microtubule fibres could be induced over a greater range of distances than RanGTP particles. The method shows how bioactive nanoparticles can be used to engineer signalling networks and spatial self-organization inside a cell environment.

Hoffmann, Céline; Mazari, Elsa; Lallet, Sylvie; Le Borgne, Roland; Marchi, Valérie; Gosse, Charlie; Gueroui, Zoher

2013-03-01

92

Taking the temperature of the interiors of magnetically heated nanoparticles.  

PubMed

The temperature increase inside mesoporous silica nanoparticles induced by encapsulated smaller superparamagnetic nanocrystals in an oscillating magnetic field is measured using a crystalline optical nanothermometer. The detection mechanism is based on the temperature-dependent intensity ratio of two luminescence bands in the upconversion emission spectrum of NaYF4:Yb(3+), Er(3+). A facile stepwise phase transfer method is developed to construct a dual-core mesoporous silica nanoparticle that contains both a nanoheater and a nanothermometer in its interior. The magnetically induced heating inside the nanoparticles varies with different experimental conditions, including the magnetic field induction power, the exposure time to the magnetic field, and the magnetic nanocrystal size. The temperature increase of the immediate nanoenvironment around the magnetic nanocrystals is monitored continuously during the magnetic oscillating field exposure. The interior of the nanoparticles becomes much hotter than the macroscopic solution and cools to the temperature of the ambient fluid on a time scale of seconds after the magnetic field is turned off. This continuous absolute temperature detection method offers quantitative insight into the nanoenvironment around magnetic materials and opens a path for optimizing local temperature controls for physical and biomedical applications. PMID:24779552

Dong, Juyao; Zink, Jeffrey I

2014-05-27

93

Magnetic nanoparticle density mapping from the magnetically induced displacement data: a simulation study  

PubMed Central

Background Magnetic nanoparticles are gaining great roles in biomedical applications as targeted drug delivery agents or targeted imaging contrast agents. In the magnetic nanoparticle applications, quantification of the nanoparticle density deposited in a specified region is of great importance for evaluating the delivery of the drugs or the contrast agents to the targeted tissues. We introduce a method for estimating the nanoparticle density from the displacement of tissues caused by the external magnetic field. Methods We can exert magnetic force to the magnetic nanoparticles residing in a living subject by applying magnetic gradient field to them. The nanoparticles under the external magnetic field then exert force to the nearby tissues causing displacement of the tissues. The displacement field induced by the nanoparticles under the external magnetic field is governed by the Navier's equation. We use an approximation method to get the inverse solution of the Navier's equation which represents the magnetic nanoparticle density map when the magnetic nanoparticles are mechanically coupled with the surrounding tissues. To produce the external magnetic field inside a living subject, we propose a coil configuration, the Helmholtz and Maxwell coil pair, that is capable of generating uniform magnetic gradient field. We have estimated the coil currents that can induce measurable displacement in soft tissues through finite element method (FEM) analysis. Results From the displacement data obtained from FEM analysis of a soft-tissue-mimicking phantom, we have calculated nanoparticle density maps. We obtained the magnetic nanoparticle density maps by approximating the Navier's equation to the Laplacian of the displacement field. The calculated density maps match well to the original density maps, but with some halo artifacts around the high density area. To induce measurable displacement in the living tissues with the proposed coil configuration, we need to apply the coil currents as big as 104A. Conclusions We can obtain magnetic nanoparticle maps from the magnetically induced displacement data by approximating the Navier's equation under the assumption of uniform-gradient of the external magnetic field. However, developing a coil driving system with the capacity of up to 104A should be a great technical challenge. PMID:22394477

2012-01-01

94

Transient magnetic birefringence for determining magnetic nanoparticle diameters in dense, highly light scattering media.  

PubMed

The increasing use of biofunctionalized magnetic nanoparticles in biomedical applications calls for further development of characterization tools that allow for determining the interactions of the nanoparticles with the biological medium in situ. In cell-incubating conditions, for example, nanoparticles may aggregate and serum proteins adsorb on the particles, altering the nanoparticles' performance and their interaction with cell membranes. In this work we show that the aggregation of spherical magnetite nanoparticles can be detected with high sensitivity in dense, highly light scattering media by making use of magnetically induced birefringence. Moreover, the hydrodynamic particle diameter distribution of anisometric nanoparticle aggregates can be determined directly in these media by monitoring the relaxation time of the magnetically induced birefringence. As a proof of concept, we performed measurements on nanoparticles included in an agarose gel, which scatters light in a similar way as a more complex biological medium but where particle-matrix interactions are weak. Magnetite nanoparticles were separated by agarose gel electrophoresis and the hydrodynamic diameter distribution was determined in situ. For the different particle functionalizations and agarose concentrations tested, we could show that gel electrophoresis did not yield a complete separation of monomers and small aggregates, and that the electrophoretic mobility of the aggregates decreased linearly with the hydrodynamic diameter. Furthermore, the rotational particle diffusion was not clearly affected by nanoparticle-gel interactions. The possibility to detect nanoparticle aggregates and their hydrodynamic diameters in complex scattering media like cell tissue makes transient magnetic birefringence an interesting technique for biological applications. PMID:22456180

Köber, Mariana; Moros, Maria; Grazú, Valeria; de la Fuente, Jesus M; Luna, Mónica; Briones, Fernando

2012-04-20

95

Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields  

E-print Network

magnetic field and the flow have been studied in details. In experiments, dilute suspension of iron oxide 1 Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields C. Magnet1 , P. Kuzhir1 , G. Bossis1 , A. Meunier1 , S. Nave1 , A. Zubarev2 , C. Lomenech3 and V

Paris-Sud XI, Université de

96

Thermoseeds for interstitial magnetic hyperthermia: from bioceramics to nanoparticles  

NASA Astrophysics Data System (ADS)

The development of magnetic materials for interstitial hyperthermia treatment of cancer is an ever evolving research field which provides new alternatives to antitumoral therapies. The development of biocompatible magnetic materials has resulted in new biomaterials with multifunctional properties, which are able to adapt to the complex scenario of tumoral processes. Once implanted or injected in the body, magnetic materials can behave as thermoseeds under the effect of AC magnetic fields. Magnetic bioceramics aimed to treat bone tumors and magnetic nanoparticles are among the most studied thermoseeds, and supply different solutions for the different scenarios in cancerous processes. This paper reviews some of the biomaterials used for bone cancer treatment and skeletal reinforcing, as well as the more complex topic of magnetic nanoparticles for intracellular targeting and hyperthermia.

Baeza, A.; Arcos, D.; Vallet-Regí, M.

2013-12-01

97

Synthesis of magnetic nanoparticles by pulsed laser ablation  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles were prepared by laser ablation of Fe foil in ethanol. The nanoparticles consisted of Fe3O4 and Fe3C and were superparamagnetic with a saturation magnetization Ms = 124 emu/g. Zero field cooled (ZFC) measurements collected at an applied field of 50 Oe displayed a maximum magnetic susceptibility at 120 K with a broad distribution. Field cooled (FC) measurements collected during cooling and heating showed a thermal hysteresis indicative of temperature dependent magnetic viscosity. The magnetic viscosity was calculated from thermoremanent magnetization (TRM) plots and it increased with decreasing temperature. The activation volume of these non uniform magnetic states was calculated from TRM measurements and it was found to decrease with decreasing temperature. The decrease in activation diameters was interpreted as a decrease in exchange length, and hence a decrease in particle-particle interactions.

Franzel, L.; Bertino, M. F.; Huba, Z. J.; Carpenter, E. E.

2012-11-01

98

"SQUID Susceptometry Imaging of Magnetic Nanoparticles" Solomon Diamond  

E-print Network

"SQUID Susceptometry Imaging of Magnetic Nanoparticles" Solomon Diamond 2010-2011 We have completed for synchronized recording of the SQUID system, encoder, and a fluxgate magnetometer and also developed software for magnetic field simulation and data analysis. We have demonstrated experimentally that the SQUID system can

Shepherd, Simon

99

Magnetic Nanoparticle Degradation in vivo Studied by Mössbauer Spectroscopy  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles belong to the most promising nanosized objects for biomedical applications. However, little is known about clearance of magnetic nanoparticles from the organism. In this work superparamagnetic iron oxide particles fluidMAG-ARA were injected into tail vein of mice at a dose of 17 mg per 20 g body weight. At various time intervals after the injection the mice were sacrificed and their organs collected. A Mössbauer study allowed to detect magnetic particles in the liver and spleen and showed the degradation of the particles with incorporation of exogenous iron into paramagnetic ferritin-like iron species.

Nikitin, Maxim; Gabbasov, Raul; Cherepanov, Valery; Chuev, Mikhail; Polikarpov, Mikhail; Panchenko, Vladislav; Deyev, Sergey

2010-12-01

100

Quantification of magnetic nanoparticles with low frequency magnetic fields: compensating for relaxation effects  

NASA Astrophysics Data System (ADS)

Quantifying the number of nanoparticles present in tissue is central to many in vivo and in vitro applications. Magnetic nanoparticles can be detected with high sensitivity both in vivo and in vitro using the harmonics of their magnetization produced in a sinusoidal magnetic field. However, relaxation effects damp the magnetic harmonics rendering them of limited use in quantification. We show that an accurate measure of the number of nanoparticles can be made by correcting for relaxation effects. Correction for relaxation reduced errors of 50% for larger nanoparticles in high relaxation environments to 2%. The result is a method of nanoparticle quantification suitable for in vivo and in vitro applications including histopathology assays, quantitative imaging, drug delivery and thermal therapy preparation.

Weaver, John B.; Zhang, Xiaojuan; Kuehlert, Esra; Toraya-Brown, Seiko; Reeves, Daniel B.; Perreard, Irina M.; Fiering, Steven

2013-08-01

101

Magnetic-plasmonic bifunctional CoO-Ag heterostructure nanoparticles  

NASA Astrophysics Data System (ADS)

We demonstrate the synthesis of CoO-Ag heterostructure nanoparticles by chemical reduction of AgNO3 in the presence of Co nanoparticles in oleylamine (OAm). OAm plays multiple roles as a surfactant, solvent, and reducing agent. The mechanism of surface-activated heterogeneous nucleation and growth on the preformed seeds has been proposed. At the same time, the Co nanoparticles are oxidized to form hollow CoO nanoparticles through the Kirkendall effect. The resulting CoO-Ag heterostructures display mushroom-like morphology, Ag nanoparticle as ‘cap’ attached on the ‘stem’ of hollow CoO nanoparticles. The size of Ag domains in the heterostructure nanoparticles can be tuned by controlling the volume of Co nanoparticles. The plasmonic absorption and the magnetization of the bifunctional nanoparticles were investigated. The combination of the hollow structure of the CoO and the surface plasmon resonances of the Ag domains may make them suitable for catalysis, drug delivery, therapy, and surface-enhanced Raman scattering.

Yang, Jianhui; Cao, Beibei; Liu, Bin

2014-03-01

102

Magnetic domains and surface effects in hollow maghemite nanoparticles  

SciTech Connect

In the present work, we investigate the magnetic properties of ferrimagnetic and non-interacting maghemite hollow nanoparticles obtained by the Kirkendall effect. From the experimental characterization of their magnetic behavior, we find that polycrystalline hollow maghemite nanoparticles exhibit low blocked-to-superparamagnetic transition temperatures, small magnetic moments, significant coercivities and irreversibility fields, and no magnetic saturation on external magnetic fields up to 5 T. These results are interpreted in terms of the microstructural parameters characterizing the maghemite shells by means of atomistic Monte Carlo simulations of an individual spherical shell. The model comprises strongly interacting crystallographic domains arranged in a spherical shell with random orientations and anisotropy axis. The Monte Carlo simulation allows discernment between the influence of the polycrystalline structure and its hollow geometry, while revealing the magnetic domain arranggement in the different temperataure regimes.

Cabot, Andreu; Alivisatos, A. Paul; Puntes, Victor; Balcells, Lluis; Iglesias, Oscar; Labarta, Amilcar

2008-09-30

103

Cell uptake enhancement of folate targeted polymer coated magnetic nanoparticles.  

PubMed

Dual targeted drug delivery systems represent a potential platform for developing efficient vector to tumor sites. In this study we evaluated a folate- and magnetic-targeted nanocarriers based on 10 nm iron oxide nanodomais coated with the properly synthesized and characterized folic acid (FA)-functionalized amphiphilic copolymer PHEA-PLA-PEG-FA. FA was chemically conjugated to one end of diamino-polyethylene glycol of 2000 Da, in order to ensure its exposition on the polymer coated magnetic nanoparticles (MNPs-FA). The prepared nanoparticles have been exhaustively characterized by different methods, including DLS, SEM, FT-IR and magnetic measurements. Magnetic nanoparticles showed dimension of about 37 nm with a narrow size distribution and a characteristic superparamagnetic behaviour. The lack of cytotoxicity of MNPs-FA and MNPs was assessed both on MCF7 cells, used as a model tumor cell line, and on 16HBE, used as normal human cell model, by evaluating cell viability using MTS assay, while the preferential internalization of MNPs-FA into tumor cells rather that into normal cells was confirmed by the quantization of internalized iron oxide. Uptake studies were also performed in the presence of a permanent magnet in order to verify the synergistic effect of magnetic field in enhancing the internalization of magnetic nanoparticles. Finally, real-time confocal microscopy experiments were carried out to further confirmed that FA ligand enhances the MNPs-FA accumulation into cancer cell cytoplasm. PMID:23858959

Licciardi, Mariano; Scialabba, Cinzia; Cavallaro, Gennara; Sangregorio, Claudio; Fantechi, Elvira; Giammona, Gaetano

2013-06-01

104

Targeted magnetic iron oxide nanoparticles for tumor imaging and therapy  

PubMed Central

Magnetic iron oxide (IO) nanoparticles with a long blood retention time, biodegradability and low toxicity have emerged as one of the primary nanomaterials for biomedical applications in vitro and in vivo. IO nanoparticles have a large surface area and can be engineered to provide a large number of functional groups for cross-linking to tumor-targeting ligands such as monoclonal antibodies, peptides, or small molecules for diagnostic imaging or delivery of therapeutic agents. IO nanoparticles possess unique paramagnetic properties, which and generate significant susceptibility effects resulting in strong T2 and T2* contrast, as well as T1 effects at very low concentrations for magnetic resonance imaging (MRI), which is widely used for clinical oncology imaging. We review recent advances in the development of targeted IO nanoparticles for tumor imaging and therapy. PMID:18990940

Peng, Xiang-Hong; Qian, Ximei; Mao, Hui; Wang, Andrew Y; Chen, Zhuo (Georgia); Nie, Shuming; Shin, Dong M

2008-01-01

105

Dynamic optical probing of the magnetic anisotropy of nickelferrite nanoparticles  

Microsoft Academic Search

Field dependence of dynamic magneto-orientational birefringence in a ferrocolloid based on the nickel-ferrite nanoparticles is examined. The nanoparticles are electrostatically stabilized and suspended in glycerin at low-volume fractions Phi<=0.75%. The colloids are tested under crossed magnetic fields: an alternating weak (probing) and a constant strong (bias) one. By comparison to a theoretical model of the birefringence relaxation, an evaluation of

Yu. L. Raikher; V. I. Stepanov; J. Depeyrot; M. H. Sousa; F. A. Tourinho; E. Hasmonay; R. Perzynski

2004-01-01

106

Spherical magnetic nanoparticles fabricated by laser target evaporation  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles of iron oxide (MNPs) were prepared by the laser target evaporation technique (LTE). The main focus was on the fabrication of de-aggregated spherical maghemite MNPs with a narrow size distribution and enhanced effective magnetization. X-ray diffraction, transmission electron microscopy, magnetization and microwave absorption measurements were comparatively analyzed. The shape of the MNPs (mean diameter of 9 nm) was very close to being spherical. The lattice constant of the crystalline phase was substantially smaller than that of stoichiometric magnetite but larger than the lattice constant of maghemite. High value of Ms up to 300 K was established. The 300 K ferromagnetic resonance signal is a single line located at a field expected from spherical magnetic particles with negligible magnetic anisotropy. The maximum obtained concentration of water based ferrofluid was as high as 10g/l of magnetic material. In order to understand the temperature and field dependence of MNPs magnetization, we invoke the core-shell model. The nanoparticles is said to have a ferrimagnetic core (roughly 70 percent of the caliper size) while the shell consists of surface layers in which the spins are frozen having no long range magnetic order. The core-shell interactions were estimated in frame of random anisotropy model. The obtained assembly of de-aggregated nanoparticles is an example of magnetic nanofluid stable under ambient conditions even without an electrostatic stabilizer.

Safronov, A. P.; Beketov, I. V.; Komogortsev, S. V.; Kurlyandskaya, G. V.; Medvedev, A. I.; Leiman, D. V.; Larrañaga, A.; Bhagat, S. M.

2013-05-01

107

Cobalt-based Magnetic Nanoparticles: Design, Synthesis and Characterization  

NASA Astrophysics Data System (ADS)

The ever-increasing desire for more energy attainable from a smaller volume of matter has driven researchers to explore advanced materials at the molecular or even atomic size scale. Magnetic materials at the nanometer size scale have been the subject of enormous research effort worldwide for more than half a century. Different magnetic nanoparticles have shown different behavior in the absence and presence of an external magnetic field, which has led them to be categorized as soft (easy to demagnetize) or hard (resistive against demagnetization) magnets. Applications range from medical and biomedical devices to magnetic recording media and magnetic sensing have emphasized the importance of this class of materials. Soft magnetic phases have found application in power generation and magnetic targeted drug delivery, while hard magnets have been subject of extensive research for application as energy storage media. Discovery of the exchange-coupling phenomenon between the spins of two adjacent hard and soft magnetic phases which means taking advantage of both high magnetic moment of the soft phase as well as high coercivity of the hard phase has attracted scientists to develop advanced materials for energy storage with no usage of fossil fuels: clean energy. In this Dissertation, synthesis of pure phase, soft FeCo nanoparticles with high magnetic moment and hard phase CoxC nanoparticles possessing high coercivity is reported. The polyol method (chemical co-precipitating at polyhydric alcohol as reducing agent) is used to make FeCo and Co xC nanoparticles and the effects of important reaction kinetics parameters on the structure and magnetic properties of the products are studied. Careful analysis of correlations between these parameters and the properties of the magnetic particles has made synthesis of FeCo and CoxC nanoparticles with desired properties possible. Fabrication of MnAlC-FeCo heterostructures as a rare earth-free alternative for high-performance permanent magnet is also reported. To synthesize MnAlC-FeCo, mechanical alloying and dry mixing of MnAlC and FeCo nanoparticles are accomplished followed by annealing in a furnace. Morphological and magnetic properties of the nanoparticles are obtained by scanning electron microscopy (SEM), x-ray diffractometry (XRD), vibrating sample magnetometry (VSM) and physical property measuring system (PPMS) magnetometry, respectively. Overall, the achieved results in this work enable synthesis of high moment FeCo and high coercivity CoxC with desired structure and magnetic properties obtained through polyol method. In particular, this Dissertation provides the technique to fabricate cobalt carbide nanoparticles without using rare earth elements as a catalyst or as heterogeneous seed nuclei at any stage: pre-processing, synthesis and post-processing. Although the experimental results of this work suggest successful fabrication of desired materials, there are many unanswered questions and unresolved challenges regarding reaction mechanism and optimizing the magnetic properties of these materials. Therefore, some recommendations are provided at the end of this Dissertation for further studies and future work. It should be noted that, implementing first principal calculations on these particles will provide better explanations and enable prediction of structure and magnetic properties of the nanoparticles and facilitate designing more complex heterostructures.

Zamanpour, Mehdi

108

Magnetically driven micropump produced by microstereolithography with ferrite nanoparticle composite photopolymer  

Microsoft Academic Search

A photopolymer containing magnetic nanoparticles was developed for applying magnetically driven micromachines. 7-nm diameter gamma-Fe2O3 nanoparticles coated by amorphous-SiO2 was used. The concentration of the magnetic nanoparticles was optimized by ultraviolet exposure. A magnetic microrotor of 6 mm diameter was produced by a molding process with a three-dimensional master model produced by microstereolithography using the nanoparticle composite photopolymer. A viscous

S. Maruo; T. Saeki; Y. Kanazawa; Y. Ichiyanagi

2008-01-01

109

Magnetic relaxation in a suspension of antiferromagnetic nanoparticles  

NASA Astrophysics Data System (ADS)

A kinetic model is proposed to describe the low-frequency magnetodynamics of antiferromagnetic nanoparticles suspended in a fluid. Because of their small size, apart from an anisotropic magnetic susceptibility typical of antiferromagnets, these particles also have a constant magnetic moment caused by sublattice decompensation. An orientational crossover takes place in such a nanosuspension (colloid) when magnetized by a constant field: the axes of easy particle magnetization that were initially aligned along the field become oriented perpendicularly. This effect changes significantly the characteristics of the system’s magnetic response: the dynamic susceptibility spectrum and the relaxation time in a pulsed field.

Raikher, Yu. L.; Stepanov, V. I.

2008-09-01

110

Magnetic nanoparticles of core-shell structure for recoverable photocatalysts  

NASA Astrophysics Data System (ADS)

Si doped iron-iron oxide core-shell magnetic nanoparticles are presented in this paper for photocatalysis applications. The nanoparticles were fabricated by a gas phase method with control of small size. Enhanced optical absorption was observed in them compared to the ones without Si, particularly in the 310 nm-450 nm wavelength range. This active optical property is beneficial for photocatalysis in terms of the efficient hole transfer from the catalysts to the reacting chemistry groups. The nanoparticles also possess a strong and active magnetic property which provides an easy way for recyclable usage. This work offers a route towards the improvement of a photocatalytic system which integrates a nanoparticulate structure of a large surface area with effective doping and recoverability by a magnetic field.

Jing, Ying; He, Shi-Hai; Wang, Jian-Ping

2013-06-01

111

Harmonics based detection of magnetic nanoparticle dynamics for multiparameter biosensing  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles have an increasing role in the clinical and pharmaceutical realms where their physical properties can be exploited for imaging, biological and functional sensing, control of cellular processes, therapeutics, and an array of other applications. When excited by an alternating magnetic field, these particles will produce a series of harmonics. These harmonics have been exploited for in vitro particle detection and for in vivo imaging using magnetic particle imaging (MPI). Using a new technique, which we have termed magnetic spectroscopy of nanoparticle Brownian motion (MSB), we have shown how information about the physical environment of the particles can be extracted from this harmonic spectrum. A variety of physical effects have been detected and/or quantified including temperature, viscosity, nanoparticle binding, and aggregation. Further, we found these different environments to have a unique impact on the spectral signature of the nanoparticles which allows for simultaneous quantification of multiple environmental states. The thesis culminates with a study of MSB as a means for monitoring the cellular uptake of nanoparticles. Potential applications for MSB as a standalone technology and the potential for incorporation into MPI are discussed throughout.

Rauwerdink, Adam M.

112

Chemisorption on nickel nanoparticles of various shapes: Influence on magnetism  

NASA Astrophysics Data System (ADS)

Nanoparticles of nickel have been obtained in solution through reaction of an organometallic precursor, Ni(COD)2 (COD=cycloocta-1,5-diene), with dihydrogen, in the presence of various stabilizing agents. X-ray diffraction studies evidence a face-centered-cubic structure for all samples. Spherical isolated superparamagnetic nanoparticles (d˜4.5 nm) are produced in the presence of poly(N-vinylpyrrolid-2-one). They display a magnetization value comparable to that of bulk nickel, as determined from superconducting quantum iinterference device (SQUID) measurements. Exposure of the surface of the nanoparticles to CO, leading to CO coordination as monitored by infrared spectroscopy, or to methanol, strongly reduces their magnetization. This reduction corresponds respectively to one or two magnetically inactive layers of nickel atoms at the nanoparticles surface. The production of elongated nanoparticles was favored when either trioctylphosphineoxide or hexadecylamine (HDA) were used as stabilizing agents. In this case, SQUID measurements show that only HDA preserves the magnetization of the surface. This stabilizing agent was selected for the production of nickel nanorods. The influence of ligands on the effective anisotropy is discussed.

Cordente, N.; Amiens, C.; Chaudret, B.; Respaud, M.; Senocq, F.; Casanove, M.-J.

2003-11-01

113

Physical Justification for Negative Remanent Magnetization in Homogeneous Nanoparticles  

NASA Astrophysics Data System (ADS)

The phenomenon of negative remanent magnetization (NRM) has been observed experimentally in a number of heterogeneous magnetic systems and has been considered anomalous. The existence of NRM in homogenous magnetic materials is still in debate, mainly due to the lack of compelling support from experimental data and a convincing theoretical explanation for its thermodynamic validation. Here we resolve the long-existing controversy by presenting experimental evidence and physical justification that NRM is real in a prototype homogeneous ferromagnetic nanoparticle, an europium sulfide nanoparticle. We provide novel insights into major and minor hysteresis behavior that illuminate the true nature of the observed inverted hysteresis and validate its thermodynamic permissibility and, for the first time, present counterintuitive magnetic aftereffect behavior that is consistent with the mechanism of magnetization reversal, possessing unique capability to identify NRM. The origin and conditions of NRM are explained quantitatively via a wasp-waist model, in combination of energy calculations.

Gu, Shuo; He, Weidong; Zhang, Ming; Zhuang, Taisen; Jin, Yi; Elbidweihy, Hatem; Mao, Yiwu; Dickerson, James H.; Wagner, Michael J.; Torre, Edward Della; Bennett, Lawrence H.

2014-09-01

114

Physical Justification for Negative Remanent Magnetization in Homogeneous Nanoparticles  

PubMed Central

The phenomenon of negative remanent magnetization (NRM) has been observed experimentally in a number of heterogeneous magnetic systems and has been considered anomalous. The existence of NRM in homogenous magnetic materials is still in debate, mainly due to the lack of compelling support from experimental data and a convincing theoretical explanation for its thermodynamic validation. Here we resolve the long-existing controversy by presenting experimental evidence and physical justification that NRM is real in a prototype homogeneous ferromagnetic nanoparticle, an europium sulfide nanoparticle. We provide novel insights into major and minor hysteresis behavior that illuminate the true nature of the observed inverted hysteresis and validate its thermodynamic permissibility and, for the first time, present counterintuitive magnetic aftereffect behavior that is consistent with the mechanism of magnetization reversal, possessing unique capability to identify NRM. The origin and conditions of NRM are explained quantitatively via a wasp-waist model, in combination of energy calculations. PMID:25183061

Gu, Shuo; He, Weidong; Zhang, Ming; Zhuang, Taisen; Jin, Yi; ElBidweihy, Hatem; Mao, Yiwu; Dickerson, James H.; Wagner, Michael J.; Torre, Edward Della; Bennett, Lawrence H.

2014-01-01

115

Physical justification for negative remanent magnetization in homogeneous nanoparticles.  

PubMed

The phenomenon of negative remanent magnetization (NRM) has been observed experimentally in a number of heterogeneous magnetic systems and has been considered anomalous. The existence of NRM in homogenous magnetic materials is still in debate, mainly due to the lack of compelling support from experimental data and a convincing theoretical explanation for its thermodynamic validation. Here we resolve the long-existing controversy by presenting experimental evidence and physical justification that NRM is real in a prototype homogeneous ferromagnetic nanoparticle, an europium sulfide nanoparticle. We provide novel insights into major and minor hysteresis behavior that illuminate the true nature of the observed inverted hysteresis and validate its thermodynamic permissibility and, for the first time, present counterintuitive magnetic aftereffect behavior that is consistent with the mechanism of magnetization reversal, possessing unique capability to identify NRM. The origin and conditions of NRM are explained quantitatively via a wasp-waist model, in combination of energy calculations. PMID:25183061

Gu, Shuo; He, Weidong; Zhang, Ming; Zhuang, Taisen; Jin, Yi; ElBidweihy, Hatem; Mao, Yiwu; Dickerson, James H; Wagner, Michael J; Torre, Edward Della; Bennett, Lawrence H

2014-01-01

116

Magnetization temperature dependence and freezing of surface spins in magnetic fluids based on ferrite nanoparticles  

Microsoft Academic Search

Manganese and copper ferrite nanoparticles, in the size range 3.3-10.4 nm, are prepared by a hydrothermal coprecipitation process and peptized in aqueous solution. The thermal dependence of the high field magnetization is investigated in the dilute regime and the observed properties can be attributed to individual particles. Our results show that, at low temperatures, the structure of our nanoparticles can

R. Aquino; J. Depeyrot; M. H. Sousa; F. A. Tourinho; E. Dubois; R. Perzynski

2005-01-01

117

Magnetic Nanoparticle Drug Carriers and their Study by Quadrupole Magnetic Field-Flow Fractionation  

PubMed Central

Magnetic nanoparticle drug carriers continue to attract considerable interest for drug targeting in the treatment of cancers and other pathological conditions. The efficient delivery of therapeutic levels of drug to a target site while limiting nonspecific, systemic toxicity requires optimization of the drug delivery materials, the applied magnetic field, and the treatment protocol. The history and current state of magnetic drug targeting is reviewed. While initial studies involved micron-sized and larger carriers, and work with these microcarriers continues, it is the sub-micron carriers or nanocarriers that are of increasing interest. An aspect of magnetic drug targeting using nanoparticle carriers that has not been considered is then addressed. This aspect involves the variation in the magnetic properties of the nanocarriers. Quadrupole magnetic field-flow fractionation (QMgFFF) is a relatively new technique for characterizing magnetic nanoparticles. It is unique in its capability of determining the distribution in magnetic properties of a nanoparticle sample in suspension. The development and current state of this technique is also reviewed. Magnetic nanoparticle drug carriers have been found by QMgFFF analysis to be highly polydisperse in their magnetic properties, and the strength of response of the particles to magnetic field gradients is predicted to vary by orders of magnitude. It is expected that the least magnetic fraction of a formulation will contribute the most to systemic toxicity, and the depletion of this fraction will result in a more effective drug carrying material. A material that has a reduced systemic toxicity will allow higher doses of cytotoxic drugs to be delivered to the tumor with reduced side effects. Preliminary experiments involving a novel method of refining a magnetic nanoparticle drug carrier to achieve this result are described. QMgFFF is used to characterize the refined and unrefined material. PMID:19591456

Williams, P. Stephen; Carpino, Francesca; Zborowski, Maciej

2009-01-01

118

Molecular sensing with magnetic nanoparticles using magnetic spectroscopy of nanoparticle Brownian motion.  

PubMed

Functionalized magnetic nanoparticles (mNPs) have shown promise in biosensing and other biomedical applications. Here we use functionalized mNPs to develop a highly sensitive, versatile sensing strategy required in practical biological assays and potentially in vivo analysis. We demonstrate a new sensing scheme based on magnetic spectroscopy of nanoparticle Brownian motion (MSB) to quantitatively detect molecular targets. MSB uses the harmonics of oscillating mNPs as a metric for the freedom of rotational motion, thus reflecting the bound state of the mNP. The harmonics can be detected in vivo from nanogram quantities of iron within 5s. Using a streptavidin-biotin binding system, we show that the detection limit of the current MSB technique is lower than 150 pM (0.075 pmole), which is much more sensitive than previously reported techniques based on mNP detection. Using mNPs conjugated with two anti-thrombin DNA aptamers, we show that thrombin can be detected with high sensitivity (4 nM or 2 pmole). A DNA-DNA interaction was also investigated. The results demonstrated that sequence selective DNA detection can be achieved with 100 pM (0.05 pmole) sensitivity. The results of using MSB to sense these interactions, show that the MSB based sensing technique can achieve rapid measurement (within 10s), and is suitable for detecting and quantifying a wide range of biomarkers or analytes. It has the potential to be applied in variety of biomedical applications or diagnostic analyses. PMID:23896525

Zhang, Xiaojuan; Reeves, Daniel B; Perreard, Irina M; Kett, Warren C; Griswold, Karl E; Gimi, Barjor; Weaver, John B

2013-12-15

119

Optimal Halbach permanent magnet designs for maximally pulling and pushing nanoparticles  

Microsoft Academic Search

Optimization methods are presented to design Halbach arrays to maximize the forces applied on magnetic nanoparticles at deep tissue locations. In magnetic drug targeting, where magnets are used to focus therapeutic nanoparticles to disease locations, the sharp fall off of magnetic fields and forces with distances from magnets has limited the depth of targeting. Creating stronger forces at a depth

A. Sarwar; A. Nemirovski; B. Shapiro

120

Magnetic Core-Shell Morphology of Structurally Uniform Magnetite Nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic nanoscale structures are intriguing, in part, because of the exotic properties that emerge compared with bulk. The reduction of magnetic moment per atom in magnetite with decreasing nanoparticle size, for example, has been hypothesized to originate from surface disordering to anisotropy-induced radial canting, which are difficult to distinguish using conventional magnetometry. Small-angle neutron scattering (SANS) is ideal for probing structure, both chemical and magnetic, from nm to microns across an ensemble of particles. Adding polarization analysis (PASANS) of the neutron spin orientation before and after interaction with the scattering particles allows the magnetic structure to be separated into its vector components. Application of this novel technique to 9 nm magnetite nanoparticles closed-packed into face-centered crystallites with order of a micron revealed that at nominal saturation the missing magnetic moments unexpectedly interacted to form well-ordered shells 1.0 to 1.5 nm thick canted perpendicular to their ferrimagnetic cores between 160 to 320 K [1]. These shells additionally displayed intra-particle "cross-talk", selecting a common orientation over clusters of tens of nanoparticles. However, the shells disappeared when the external field was removed and interparticle magnetic interactions were negligible (300 K), confirming their magnetic origin. This work has been carried out in collaboration with Ryan Booth, Julie Borchers, Wangchun Chen, Liv Dedon, Thomas Gentile, Charles Hogg, Yumi Ijiri, Mark Laver, Sara Majetich, James Rhyne, and Shannon Watson.[4pt] [1] K.L. Krycka et al., Phys. Rev. Lett. 104, 207203 (2010)

Krycka, Kathryn

2011-03-01

121

Bacterial Magnetic Nanoparticles as Peroxidase Mimetics and Application in Immunoassay  

NASA Astrophysics Data System (ADS)

Although progress in nanosynthesis has succeeded in making nanoscale particles from iron oxide, the research about natural magnetic nanoparticles, magnetosomes, is still a current interest because of their intrinsic magnetic features, nano-features, membrane-enclosed features and genetic control of size and morphology properties. In this study, we investigated magnetosomes' intrinsic peroxidase-like activity similar to that found in artificial magnetic nanoparticles. We characterized the catalytic activity by varying the method of extraction and storage, the pH value, the temperature and the H2O2 concentration. Based on these finding, we developed a simplified immunoassay approach to use magnetosomes as a peroxidase mimic catalyst and a magnetic separator as well.

Hu, Lili; Song, Tao; Ma, Qiufeng; Chen, Chuanfang; Pan, Weidong; Xie, Chunlan; Nie, Leng; Yang, Wenhui

2010-12-01

122

Magnetic single-enzyme nanoparticles with high activity and stability  

SciTech Connect

Magnetic single-enzyme nanoparticles (SENs) encapsulated within a composite inorganic/organic polymer network were fabricated via the surface modification and in situ aqueous polymerization of separate enzyme molecule. The resultant nanoparticles were characterized by transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectrometer and X-ray diffraction (XRD). These particles are almost spherical in shape and have a unique size of about 50 nm in diameter. Electrical and magnetic measurements reveal that the magnetic SENs have a conductivity of 2.7 x 10{sup -3} S cm{sup -1}, and are superparamagnetic with a saturation magnetization of 14.5 emu g{sup -1} and a coercive force of 60 Oe. Compared with free enzyme, encapsulated enzyme exhibits a strong tolerance to the variation of solution pH, high temperature, organic solvent and long-term storage, thus showing significantly enhanced enzyme performance and stability.

Yang Zhengpeng [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Institute of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454000 (China); Si Shihui [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)], E-mail: sishihui@mail.csu.edu.cn; Zhang Chunjing [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Institute of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454000 (China)

2008-02-29

123

Magnetic nanoparticle targeted hyperthermia of cutaneous Staphylococcus aureus infection  

PubMed Central

The incidence of wound infections that do not adequately respond to standard-of-care antimicrobial treatment has been increasing. To address this challenge, a novel antimicrobial magnetic thermotherapy platform has been developed in which a high-amplitude, high-frequency, alternating magnetic field (AMF) is used to rapidly heat magnetic nanoparticles that are bound to Staphylococcus aureus (S. aureus). The antimicrobial efficacy of this platform was evaluated in the treatment of both an in vitro culture model of S. aureus biofilm and a mouse model of cutaneous S. aureus infection. We demonstrated that an antibody-targeted magnetic nanoparticle bound to S. aureus was effective at thermally inactivating S. aureus and achieving accelerated wound healing without causing tissue injury. PMID:23149904

Kim, Min-Ho; Yamayoshi, Itsukyo; Mathew, Steven; Liln, Hubert; Nayfach, Joseph; Simon, Scott I.

2013-01-01

124

Magnetic Heating of Iron Oxide Nanoparticles and Magnetic Micelles for Cancer Therapy  

PubMed Central

The inclusion of magnetic nanoparticles into block copolymer micelles was studied towards the development of a targeted, magnetically triggered drug delivery system for cancer therapy. Herein, we report the synthesis of magnetic nanoparticles and poly(ethylene glycol-b-caprolactone) block copolymers, and experimental verification of magnetic heating of the nanoparticles, self-assembly of the block copolymers to form magnetic micelles, and thermally-enhanced drug release. The semicrystalline core of the micelles melted at temperatures just above physiological conditions, indicating that they could be used to release a chemotherapy agent from a thermo-responsive polymer system. The magnetic nanoparticles were shown to heat effectively in high frequency magnetic fields ranging from 30–70 kA/m. Magnetic micelles also showed heating properties, that when combined with a chemotherapeutic agent and a targeting ligand could be developed for localized, triggered drug delivery. During the magnetic heating experiments, a time lag was observed in the temperature profile for magnetic micelles, likely due to the heat of fusion of melting of polycaprolactone micelle cores before bulk solution temperatures increased. Doxorubicin, incorporated into the micelles, released faster when the micelles were heated above the core melting point. PMID:23750047

Glover, Amanda L.; Bennett, James B.; Pritchett, Jeremy S.; Nikles, Sarah M.; Nikles, David E.; Nikles, Jacqueline A.; Brazel, Christopher S.

2013-01-01

125

Magnetic core shell nanoparticles trapping in a microdevice generating high magnetic gradient.  

PubMed

Magnetic core shell nanoparticles (MCSNPs) 30 nm diameter with a magnetic weight of 10% are usually much too small to be trapped in microfluidic systems using classical external magnets. Here, a simple microchip for efficient MCSNPs trapping and release is presented. It comprises a bed of micrometric iron beads (6-8 ?m diameter) packed in a microchannel against a physical restriction and presenting a low dead volume of 0.8 nL. These beads of high magnetic permeability are used to focus magnetic field lines from an external permanent magnet and generate local high magnetic gradients. The nanoparticles magnetic trap has been characterised both by numerical simulations and fluorescent MCSNPs imaging. Numerical simulations have been performed to map both the magnetic flux density and the magnetic force, and showed that MCSNPs are preferentially trapped at the iron bead magnetic poles where the magnetic force is increased by 3 orders of magnitude. The trapping efficiency was experimentally determined using fluorescent MCSNPs for different flow rates, different iron beads and permanent magnet positions. At a flow rate of 100 ?L h(-1), the nanoparticles trapping/release can be achieved within 20 s with a preconcentration factor of 4000. PMID:21253647

Teste, Bruno; Malloggi, Florent; Gassner, Anne-Laure; Georgelin, Thomas; Siaugue, Jean-Michel; Varenne, Anne; Girault, Hubert; Descroix, Stéphanie

2011-03-01

126

Progress in electrochemical synthesis of magnetic iron oxide nanoparticles  

NASA Astrophysics Data System (ADS)

Recently, magnetic iron oxide particles have been emerged as significant nanomaterials due to its extensive range of application in various fields. In this regard, synthesis of iron oxide nanoparticles with desirable properties and high potential applications are greatly demanded. Therefore, investigation on different iron oxide phases and their magnetic properties along with various commonly used synthetic techniques are remarked and thoroughly described in this review. Electrochemical synthesis as a newfound method with unique advantages is elaborated, followed by design approaches and key parameters to control the properties of the iron oxide nanoparticles. Additionally, since the dispersion of iron oxide nanoparticles is as important as its preparation, surface modification issue has been a serious challenge which is comprehensively discussed using different surfactants. Despite the advantages of the electrochemical synthesis method, this technique has been poorly studied and requires deep investigations on effectual parameters such as current density, pH, electrolyte concentration etc.

Ramimoghadam, Donya; Bagheri, Samira; Hamid, Sharifah Bee Abd

2014-11-01

127

A two rotor model with spin for magnetic nanoparticles.  

PubMed

We argue that a kind of magnetic nanoparticle might exist characterized by the locking of the constituent spins with the density profile of the macrospin. We represent such a nanoparticle by two interacting rigid rotors, one of which has a large spin attached to the body, namely a two rotor model with spin. By this model we can describe in a unified way the cases of nanoparticles free and stuck in an elastic or a rigid matrix. We evaluate the magnetic susceptibility for the latter case and under some realistic assumptions we get results in closed form. A crossover between thermal and purely quantum hopping occurs at a temperature much higher than that at which tunneling becomes important. Agreement with some experimental data is remarkable. PMID:25285404

Hatada, Keisuke; Hayakawa, Kuniko; Marcelli, Augusto; Palumbo, Fabrizio

2014-11-21

128

Evaluation of Magnetic Micro and Nanoparticle Toxicity to Ocular Tissues  

Microsoft Academic Search

PurposeMagnetic nanoparticles (MNPs) may be used for focal delivery of plasmids, drugs, cells, and other applications. Here we ask whether such particles are toxic to ocular structures.MethodsTo evaluate the ocular toxicity of MNPs, we asked if either 50 nm or 4 µm magnetic particles affect intraocular pressure, corneal endothelial cell count, retinal morphology including both cell counts and glial activation,

Hemalatha B. Raju; Ying Hu; Anil Vedula; Sander R. Dubovy; Jeffrey L. Goldberg; Neeraj Vij

2011-01-01

129

Exchange bias properties and surface spin freezing in magnetic nanoparticles  

Microsoft Academic Search

ZFC and FC magnetization measurements versus field are carried out on manganese ferrite based nanoparticles with a mean diameter of 3.3 nm. The exchange bias field determined from the field shift of hysteresis loops, decreases as the cooling field increases. Magnetization measurements performed at constant applied field H as a function of temperature allows us to separate two H-dependent contributions. One

F. G. Silva; R. Aquino; J. Depeyrot; F. A. Tourinho; V. Dupuis; R. Perzynski

2010-01-01

130

Computational studies of steering nanoparticles with magnetic gradients  

NASA Astrophysics Data System (ADS)

Magnetic Resonance Imaging (MRI) guided nanorobotic systems that could perform diagnostic, curative, and reconstructive treatments in the human body at the cellular and subcellular level in a controllable manner have recently been proposed. The concept of a MRI-guided nanorobotic system is based on the use of a MRI scanner to induce the required external driving forces to guide magnetic nanocapsules to a specific target. However, the maximum magnetic gradient specifications of existing clinical MRI systems are not capable of driving magnetic nanocapsules against the blood flow. This thesis presents the visualization of nanoparticles inside blood vessel, Graphical User Interface (GUI) for updating file including initial parameters and demonstrating the simulation of particles and C++ code for computing magnetic forces and fluidic forces. The visualization and GUI were designed using Virtual Reality Modeling Language (VRML), MATLAB and C#. The addition of software for MRI-guided nanorobotic system provides simulation results. Preliminary simulation results demonstrate that external magnetic field causes aggregation of nanoparticles while they flow in the vessel. This is a promising result --in accordance with similar experimental results- and encourages further investigation on the nanoparticle-based self-assembly structures for use in nanorobotic drug delivery.

Aylak, Sultan Suleyman

131

Maximizing hysteretic losses in magnetic ferrite nanoparticles via model-driven synthesis and materials optimization.  

PubMed

This article develops a set of design guidelines for maximizing heat dissipation characteristics of magnetic ferrite MFe2O4 (M = Mn, Fe, Co) nanoparticles in alternating magnetic fields. Using magnetic and structural nanoparticle characterization, we identify key synthetic parameters in the thermal decomposition of organometallic precursors that yield optimized magnetic nanoparticles over a wide range of sizes and compositions. The developed synthetic procedures allow for gram-scale production of magnetic nanoparticles stable in physiological buffer for several months. Our magnetic nanoparticles display some of the highest heat dissipation rates, which are in qualitative agreement with the trends predicted by a dynamic hysteresis model of coherent magnetization reversal in single domain magnetic particles. By combining physical simulations with robust scalable synthesis and materials characterization techniques, this work provides a pathway to a model-driven design of magnetic nanoparticles tailored to a variety of biomedical applications ranging from cancer hyperthermia to remote control of gene expression. PMID:24016039

Chen, Ritchie; Christiansen, Michael G; Anikeeva, Polina

2013-10-22

132

nanoparticles  

NASA Astrophysics Data System (ADS)

In this paper, we report the observation of intrinsic room temperature ferromagnetism in pure La2O3 nanoparticles. Magnetism measurement indicates that all of the samples exhibit room temperature ferromagnetism and the saturation magnetization for the samples decreases with the increase in annealing temperature from 700 to 1,000 °C. X-ray photoelectron spectroscopy identifies the presence of oxygen vacancies in the La2O3 nanoparticles. The fitting results of the O 1 s spectrum indicate that the variation of the oxygen vacancy concentration is in complete agreement with the change of the saturation magnetization. It is also found that the saturation magnetization of the La2O3 nanoparticles can be tuned by post-annealing in argon or oxygen atmosphere. These results suggest that the oxygen vacancies are largely responsible for the room temperature ferromagnetism in pure La2O3 nanoparticles.

Xu, Qiang; Gao, Daqiang; Zhang, Jing; Yang, Zhaolong; Zhang, Zhipeng; Rao, Jinwei; Xue, Desheng

2014-09-01

133

Intracellular manipulation of chromatin using magnetic nanoparticles  

Microsoft Academic Search

Magnetic tweezers are widely used for manipulating small magnetic beads inside the cell cytoplasm in order to gain insight\\u000a into the structural and mechanical properties of the cytoskeleton. Here we discuss the use of magnetic tweezers for the study\\u000a of nuclear architecture and the mechanical properties of chromatin in living cells. A custom-built, dedicated micro magnetic\\u000a tweezer set-up is described.

Johannes S. Kanger; Vinod Subramaniam; Roel van Driel

2008-01-01

134

Radio-wave heating of iron oxide nanoparticles can regulate plasma glucose in mice.  

PubMed

Medical applications of nanotechnology typically focus on drug delivery and biosensors. Here, we combine nanotechnology and bioengineering to demonstrate that nanoparticles can be used to remotely regulate protein production in vivo. We decorated a modified temperature-sensitive channel, TRPV1, with antibody-coated iron oxide nanoparticles that are heated in a low-frequency magnetic field. When local temperature rises, TRPV1 gates calcium to stimulate synthesis and release of bioengineered insulin driven by a Ca(2+)-sensitive promoter. Studying tumor xenografts expressing the bioengineered insulin gene, we show that exposure to radio waves stimulates insulin release from the tumors and lowers blood glucose in mice. We further show that cells can be engineered to synthesize genetically encoded ferritin nanoparticles and inducibly release insulin. These approaches provide a platform for using nanotechnology to activate cells. PMID:22556257

Stanley, Sarah A; Gagner, Jennifer E; Damanpour, Shadi; Yoshida, Mitsukuni; Dordick, Jonathan S; Friedman, Jeffrey M

2012-05-01

135

Development of Novel Magnetic Nanoparticles for Hyperthermia Cancer Therapy  

PubMed Central

Advances in magnetic nanoparticle hyperthermia are opening new doors in cancer therapy. As a standalone or adjuvant therapy this new modality has the opportunity significantly advance thermal medicine. Major advantages of using magnetic magnetite (Fe3O4) nanoparticles are their highly localized power deposition and the fact that the alternating magnetic fields (AMF) used to excite them can penetrate deeply into the body without harmful effect. One limitation, however, which hinders the technology, is the problem of inductive heating of normal tissue by the AMF if the frequency and fields strength are not appropriately matched to the tissue. Restricting AMF amplitude and frequency limits the heat dose which can be selectively applied to cancerous tissue via the magnetic nanoparticle, thus lowering therapeutic effect. In an effort to address this problem, particles with optimized magnetic properties must be developed. Using particles with higher saturation magnetizations and coercivity will enhance hysteresis heating increasing particle power density at milder AMF strengths and frequencies. In this study we used oil in water microemulsions to develop nanoparticles with zero-valent Fe cores and magnetite shells. The superior magnetic properties of zero-valent Fe give these particles the potential for improved SAR over pure magnetite particles. Silane and subsequently dextran have been attached to the particle surface in order to provide a biocompatible surfactant coating. The heating capability of the particles was tested in-vivo using a mouse tumor model. Although we determined that the final stage of synthesis, purification of the dextran coated particles, permits significant corrosion/oxidation of the iron core to hematite, the particles can effectively heat tumor tissue. Improving the purification procedure will allow the generation Fe/Fe3O4 with superior SAR values. PMID:24619487

Cassim, Shiraz M.; Giustini, Andrew J.; Baker, Ian; Hoopes, P. Jack

2013-01-01

136

Detection of breast cancer cells using targeted magnetic nanoparticles and ultra-sensitive magnetic field sensors  

PubMed Central

Introduction Breast cancer detection using mammography has improved clinical outcomes for many women, because mammography can detect very small (5 mm) tumors early in the course of the disease. However, mammography fails to detect 10 - 25% of tumors, and the results do not distinguish benign and malignant tumors. Reducing the false positive rate, even by a modest 10%, while improving the sensitivity, will lead to improved screening, and is a desirable and attainable goal. The emerging application of magnetic relaxometry, in particular using superconducting quantum interference device (SQUID) sensors, is fast and potentially more specific than mammography because it is designed to detect tumor-targeted iron oxide magnetic nanoparticles. Furthermore, magnetic relaxometry is theoretically more specific than MRI detection, because only target-bound nanoparticles are detected. Our group is developing antibody-conjugated magnetic nanoparticles targeted to breast cancer cells that can be detected using magnetic relaxometry. Methods To accomplish this, we identified a series of breast cancer cell lines expressing varying levels of the plasma membrane-expressed human epidermal growth factor-like receptor 2 (Her2) by flow cytometry. Anti-Her2 antibody was then conjugated to superparamagnetic iron oxide nanoparticles using the carbodiimide method. Labeled nanoparticles were incubated with breast cancer cell lines and visualized by confocal microscopy, Prussian blue histochemistry, and magnetic relaxometry. Results We demonstrated a time- and antigen concentration-dependent increase in the number of antibody-conjugated nanoparticles bound to cells. Next, anti Her2-conjugated nanoparticles injected into highly Her2-expressing tumor xenograft explants yielded a significantly higher SQUID relaxometry signal relative to unconjugated nanoparticles. Finally, labeled cells introduced into breast phantoms were measured by magnetic relaxometry, and as few as 1 million labeled cells were detected at a distance of 4.5 cm using our early prototype system. Conclusions These results suggest that the antibody-conjugated magnetic nanoparticles are promising reagents to apply to in vivo breast tumor cell detection, and that SQUID-detected magnetic relaxometry is a viable, rapid, and highly sensitive method for in vitro nanoparticle development and eventual in vivo tumor detection. PMID:22035507

2011-01-01

137

Enhanced spontaneous magnetization in the core of nickel nanoparticles  

NASA Astrophysics Data System (ADS)

It is conceptually expected that the decrease of the size of a ferromagnetic body may narrow the energy bands of 3d electrons, so that the spontaneous magnetization Ms will increase from the value for the bulk to that corresponding to the moment of individual magnetic ion. However, most experiments for nickel nanoparticles show Ms to decrease with the decreasing particle size. Such a phenomenon for ferrimagnetic nanoparticles may be explained by a core-shell model with the spontaneous magnetization Ms having the value of the bulk in the core and zero in the shell. In the present work, the size distribution of an assembly of fcc nickel nanoparticles is determined by transmission electron microscopy to well follow a normal probability density function. Using such a function, the measured magnetization curves of the assembly are simulated by the core-shell model. It has been found that although the average Ms is much smaller than that of the bulk, Ms in the core turns out to be much larger than that in the bulk, which seems to support the above-mentioned expectation. The enhanced Ms in the core might result from the effect of core-shell boundary, which narrows the energy bands of 3d electrons of the nickel core. Nevertheless, the magnetic core-shell structure itself is difficult to be completely understood at the moment.

Chen, D.-X.; Pascu, O.; Roig, A.

2014-08-01

138

Dynamic nanomagnetism characterization of individual magnetic nanoparticles by frequency-modulated magnetic force microscopy  

NASA Astrophysics Data System (ADS)

In this study, stroboscopic imaging of an alternating magnetic field (AC magnetic field) from individual superparamagnetic Fe3O4 nanoparticles was achieved using the developed frequency modulated-magnetic force microscopy (FM-MFM) technique, which enables the imaging of the vector signals of AC magnetic fields, such as a combination of in-phase and quadrature signals or that of amplitude and phase signals. FM-MFM uses the frequency modulation of cantilever oscillation, caused by the application of an off-resonant AC magnetic field to a mechanically oscillated cantilever, and visualises the vector signals of the AC magnetic field by adding a frequency demodulator and a lock-in amplifier to a conventional magnetic force microscope. Stroboscopic imaging of an AC magnetic field was carried out by varying the phase of the measured in-phase and quadrature signals via a signal processing technique. For the superparamagnetic Fe3O4 nanoparticles, stroboscopic imaging of the time-variable AC magnetic field, caused by the rotation of the magnetic moments within the particles, was demonstrated. This article describes the present status of FM-MFM technology, with particular attention to the feasibility of detecting magnetic moments of individual nanoparticles, and the possible application of FM-MFM in biological imaging.

Li, Xiang; Li, Zhenghua; Pan, Deng; Yoshimura, Satoru; Saito, Hitoshi

2014-05-01

139

Laser-driven synthesis and magnetic properties of iron nanoparticles Yuanqing He1,4  

E-print Network

Nanoparticles of iron have been prepared by laser-driven decomposition of iron pentacarbonyl vaporLaser-driven synthesis and magnetic properties of iron nanoparticles Yuanqing He1,4 , Yudhisthira form 6 July 2005 Key words: CO2 laser, aerosol synthesis, magnetic, iron, nanoparticle Abstract

Swihart, Mark T.

140

Use of Magnetic Nanoparticles to Visualize Threadlike Structures inside Lymphatic Vessels of Rats  

Microsoft Academic Search

A novel application of fluorescent magnetic nanoparticles was made to visualize a new tissue which had not been detectable by using simple stereomicroscopes. This unfamiliar threadlike structure inside the lymphatic vessels of rats was demonstrated in vivo by injecting nanoparticles into lymph nodes and applying magnetic fields on the collecting lymph vessels so that the nanoparticles were taken up by

Hyeon-Min Johng; Jung Sun Yoo; Tae-Jong Yoon; Hak-Soo Shin; Byung-Cheon Lee; Changhoon Lee; Jin-Kyu Lee; Kwang-Sup Soh

2007-01-01

141

Isolation of DNA using magnetic nanoparticles coated with dimercaptosuccinic acid.  

PubMed

Lately, the isolation of DNA using magnetic nanoparticles has received increased attention owing to their facile manipulation and low costs. Although methods involving their magnetic separation have been extensively studied, there is currently a need for an efficient technique to isolate DNA for highly sensitive diagnostic applications. We describe herein a method to isolate and purify DNA using biofunctionalized superparamagnetic nanoparticles synthesized by a modified polyol method to obtain the desired monodispersity, followed by surface modification with meso-2,3-dimercaptosuccinic acid (DMSA) containing carboxyl groups for DNA absorption. The DMSA-coated magnetic nanoparticles (DMSA-MNPs) were used for the isolation of DNA, with a maximum yield of 86.16%. In particular, we found that the isolation of DNA using small quantities of DMSA-MNPs was much more efficient than that using commercial microbeads (NucliSENS-easyMAG, BioMérieux). Moreover, the DMSA-MNPs were successfully employed in the isolation of genomic DNA from human blood. In addition, the resulting DNA-nanoparticle complex was directly subjected to PCR amplification without prior elution, which could eventually lead to simple, rapid, sensitive and integrated diagnostic systems. PMID:24291543

Min, Ji Hyun; Woo, Mi-Kyung; Yoon, Ha Young; Jang, Jin Woo; Wu, Jun Hua; Lim, Chae-Seung; Kim, Young Keun

2014-02-15

142

Aggregation behaviour of magnetic nanoparticle suspensions investigated by magnetorelaxometry  

NASA Astrophysics Data System (ADS)

The aggregation behaviour of magnetic nanoparticles (MNP) is a decisive factor for their application in medicine and biotechnology. We extended the moment superposition model developed earlier for describing the Néel relaxation of an ensemble of immobilized particles with a given size distribution by including the Brownian relaxation mechanism. The resulting cluster moment superposition model is used to characterize the aggregation of magnetic nanoparticles in various suspensions in terms of mean cluster size, aggregate fraction, and size dispersion. We found that in stable ferrofluids 50%-80% of larger magnetic nanoparticles are organized in dimers and trimers. The scaling of the relaxation curves with respect to MNP concentration is found to be a sensitive indicator of the tendency of a MNP suspension to form large aggregates, which may limit the biocompatibility of the preparation. Scaling violation was observed in aged water based ferrofluids, and may originate from damaged MNP shells. In biological media such as foetal calf serum, bovine serum albumin, and human serum we observed an aggregation behaviour which reaches a maximum at a specific MNP concentration. We relate this to agglutination of the particles by macromolecular bridges between the nanoparticle shells. Analysis of the scaling behaviour helps to identify the bridging component of the suspension medium that causes agglutination.

Eberbeck, D.; Wiekhorst, F.; Steinhoff, U.; Trahms, L.

2006-09-01

143

Hard magnetic properties of FePd nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles FexPd100-x (x = 42, 50, 55, 60, 63) with small size of around 5-10 nm were prepared by sonochemistry from palladium acetate and iron acetate. The compositions x can be controlled by changing the ratio of the above precursor chemicals. Under the effect of annealing at various temperatures from 450 °C to 650 °C, structure change was observed and samples show hard magnetic properties with high coercivity up to 2.1 kOe. Magnetic properties of samples were then systematically discussed in dependence of x and annealing temperatures. International Workshop on Advanced Materials and Nanotechnology 2012 (IWAMN 2012).

Thi Thanh Van, Nguyen; Thanh Trung, Truong; Hoang Nam, Nguyen; Dang Phu, Nguyen; Hoang Hai, Nguyen; Hoang Luong, Nguyen

2013-10-01

144

Synthesis and assembly of magnetic nanoparticles for information and energy storage applications  

NASA Astrophysics Data System (ADS)

This mini-review summarizes the recent advances in chemical synthesis and assembly of monodisperse magnetic nanoparticles for magnetic applications. After a brief introduction to nanomagnetism, the review focuses on recent developments in solution phase syntheses and assemblies of monodisperse Fe, CoFe, FePt and SmCo5 nanoparticles. The review further outlines the structural and magnetic properties of these nanoparticles for magnetic information and energy storage applications.

Zhang, Hong-Wang; Liu, Yi; Sun, Shou-Heng

2010-12-01

145

Intracellular manipulation of chromatin using magnetic nanoparticles.  

PubMed

Magnetic tweezers are widely used for manipulating small magnetic beads inside the cell cytoplasm in order to gain insight into the structural and mechanical properties of the cytoskeleton. Here we discuss the use of magnetic tweezers for the study of nuclear architecture and the mechanical properties of chromatin in living cells. A custom-built, dedicated micro magnetic tweezer set-up is described. We review progress that has been made in applying this technology for the study of chromatin structure and discuss its prospects for the in situ analysis of nuclear architecture and chromatin function. PMID:18461487

Kanger, Johannes S; Subramaniam, Vinod; van Driel, Roel

2008-01-01

146

Magnetic nanoparticle transport within flowing blood and into surrounding tissue  

PubMed Central

Magnetic drug delivery refers to the physical confinement of therapeutic magnetic nanoparticles to regions of disease, tumors, infections and blood clots. Predicting the effectiveness of magnetic focusing in vivo is critical for the design and use of magnetic drug delivery systems. However, current simple back-of-the-envelope estimates have proven insufficient for this task. In this article, we present an analysis of nanoparticle distribution, in and around a single blood vessel (a Krogh tissue cylinder), located at any depth in the body, with any physiologically relevant blood flow velocity, diffusion and extravasation properties, and with any applied magnetic force on the particles. For any such blood vessel our analysis predicts one of three distinct types of particle behavior (velocity dominated, magnetic dominated or boundary-layer formation), which can be uniquely determined by looking up the values of three nondimensional numbers we define. We compare our predictions to previously published magnetic-focusing in vitro and in vivo studies. Not only do we find agreement between our predictions and prior observations, but we are also able to quantitatively explain behavior that was not understood previously. PMID:21128726

Nacev, A; Beni, C; Bruno, O; Shapiro, B

2011-01-01

147

Optimizing Magnetite Nanoparticles for Mass Sensitivity in Magnetic Particle Imaging  

SciTech Connect

Purpose: Magnetic particle imaging (MPI), using magnetite nanoparticles (MNPs) as tracer material, shows great promise as a platform for fast tomographic imaging. To date, the magnetic properties of MNPs used in imaging have not been optimized. As nanoparticle magnetism shows strong size dependence, we explore how varying MNP size impacts imaging performance in order to determine optimal MNP characteristics for MPI at any driving field frequency, ?. Methods: Monodisperse MNPs of varying size were synthesized and their magnetic properties characterized. Their MPI response was measured experimentally, at an arbitrarily chosen ? = 250 kHz, using a custom-built MPI transceiver designed to detect the third harmonic of MNP magnetization. Results were interpreted using a model of dynamic MNP magnetization that is based on the Langevin theory of superparamagnetism and accounts for sample size distribution, and size-dependent magnetic relaxation. Results: Our experimental results show clear variation in the MPI signal intensity as a function of MNP size that is in good agreement with modeled results. A maxima in the plot of MPI signal vs. MNP size indicates there is a particular size that is optimal for the chosen frequency of 250 kHz. Conclusions: For MPI at any chosen frequency, there will exist a characteristic particle size that generates maximum signal amplitude. We illustrate this at 250 kHz with particles of 15 nm core diameter.

Ferguson, R. Matthew; Minard, Kevin R.; Khandhar, Amit P.; Krishnan, Kannan M.

2011-03-01

148

Magnetic properties of ultra-small goethite nanoparticles  

NASA Astrophysics Data System (ADS)

Goethite (?-FeOOH) is a common nanocrystalline antiferromagnetic mineral. However, it is typically difficult to study the properties of isolated single-crystalline goethite nanoparticles, because goethite has a strong tendency to form particles of aggregated nanograins often with low-angle grain boundaries. This nanocrystallinity leads to complex magnetic properties that are dominated by magnetic fluctuations in interacting grains. Here we present a study of the magnetic properties of 5.7 nm particles of goethite by use of magnetization measurements, inelastic neutron scattering and Mössbauer spectroscopy. The ‘ultra-small’ size of these particles (i.e. that the particles consist of one or only a few grains) allows for more direct elucidation of the particles' intrinsic magnetic properties. We find from ac and dc magnetization measurements a significant upturn of the magnetization at very low temperatures most likely due to freezing of spins in canted spin structures. From hysteresis curves we estimate the saturation magnetization from uncompensated magnetic moments to be ?s = 0.044 A m2 kg-1 at room temperature. Inelastic neutron scattering measurements show a strong signal from excitations of the uniform mode (q = 0 spin waves) at temperatures of 100-250 K and Mössbauer spectroscopy studies show that the magnetic fluctuations are dominated by ‘classical’ superparamagnetic relaxation at temperatures above ˜170 K. From the temperature dependence of the hyperfine fields and the excitation energy of the uniform mode we estimate a magnetic anisotropy constant of around 1.0 × 105 J m-3.

Brok, E.; Frandsen, C.; Madsen, D. E.; Jacobsen, H.; Birk, J. O.; Lefmann, K.; Bendix, J.; Pedersen, K. S.; Boothroyd, C. B.; Berhe, A. A.; Simeoni, G. G.; Mørup, S.

2014-09-01

149

Crosswell Magnetic Sensing of Superparamagnetic Nanoparticles for Subsurface Applications  

NASA Astrophysics Data System (ADS)

Stable dispersions of superparamagnetic nanoparticles, already used in biomedicine as image-enhancing agents, have potential in subsurface applications. The surface-coated nanoparticles are capable of flowing through micron-size pores across long distances in a reservoir with minimal retention in rock. These particles change the magnetic permeability of the flooded region, and when added to the injected fluid during enhanced oil recovery processes, they can be used to tag the flood. In this paper, we model the propagation of a "ferrofluid" slug in a reservoir and its response to a crosswell magnetic tomography system. The magnetic response to these contrast agents can thus help characterize the formation and fluid displacement mechanisms. The monitoring of fluid injections into reservoirs builds upon the established EM conductivity monitoring technology. In this work, however, particular attention is paid to distinguish the injected and resident fluids when they have similar conductivities but different magnetic permeabilities. Specifically, we focus on low-frequency (less than 100 Hz) magnetic excitations generated by a vertical magnetic dipole source positioned at the injection well. At such low frequencies, the induction effect is small, the casing effect is manageable, and the crosswell response originates purely from the magnetic contrast in the formation. In this study, we assume a 2d axisymmetric model and track a donut-shaped ferrofluid slug of magnetic permeability 2 as it propagates toward an observatory well, housing magnetic field receivers and located 100 m away from the injection well. We apply vertical magnetic dipole source and receivers at multiple levels within the tomography section. A non-magnetic and non-conductive casing is assumed for both wells. The ferrofluid slug volume is conserved throughout the dispersionless propagation and confined within a 20 m thick reservoir layer at a depth of 1 Km. We compare the response of a conductive slug with that of a ferrofluid slug both at low and high frequencies.

Rahmani, A.; Athey, A.; Wilt, M.; Chen, J.

2012-12-01

150

Controlling nanoparticle delivery in magnetic nanoparticle hyperthermia for cancer treatment: experimental study in agarose gel.  

PubMed

In magnetic nanoparticle hyperthermia for cancer treatment, controlling the heat distribution and temperature elevations is an immense challenge in clinical applications. In this study we evaluate magnetic nanofluid transport and heat distribution induced by commercially available magnetic nanoparticles injected into the extracellular space of biological tissue using agarose gel with porous structures similar to human tissue. The nanofluid distribution in the gel is examined via digital images of the nanofluid spreading in the gel. A radio-frequency electromagnetic field is applied to the gel following the nanofluid injection and the initial rates of temperature rise at various locations are measured to obtain the specific absorption rate (SAR) distribution. By adjusting the gel concentration and injection flow rate, the results have demonstrated that a relatively low injection rate leads to a spherically shaped nanofluid distribution in the gels which is desirable for controlling temperature elevations. The SAR distribution shows that the nanoparticle distribution in the gel is not uniform with a high concentration of the nanoparticles close to the injection site. We believe that the experimental study is the first step towards providing guidance for designing better treatment protocol for future clinical applications. PMID:18465418

Salloum, M; Ma, R H; Weeks, D; Zhu, L

2008-06-01

151

Magnetic properties of iron nanoparticles in a polymer film  

NASA Astrophysics Data System (ADS)

We systematically synthesized self-aggregated iron nanoparticles in the perfluorinated sulfo-cation membrane (MF-4SK) by ion-exchange method. Our experimental results show that iron nanoparticles in MF-4SK exhibit superparamagnetic properties above the blocking temperature. Field-cooled and zero-field-cooled magnetization data show the blocking temperature, TB?120 K for the iron concentration of 5×10 19 atoms per 1 g of polymer film at 500 Oe applied field. This result is well matched with the calculation based on the temperature dependence of the coercivity, which shows TB?110 K, with the zero temperature coercivity ( HC0) ? 420 Oe. The radius of the typical iron particle is determined to be ˜2 nm from transmission electron microscopy (TEM), showing good agreement with the value acquired by Langevin function fit. These experimental evidences suggest that iron nanoparticles in the polymer film obey a single-domain theory.

Yoon, M.; Kim, Y. M.; Kim, Y.; Volkov, V.; Song, H. J.; Park, Y. J.; Vasilyak, S. L.; Park, I.-W.

2003-10-01

152

Study of local magnetic fields and magnetic ordering in fluid and solid matrices containing magnetite nanoparticles using TEMPOL stable radical  

NASA Astrophysics Data System (ADS)

The stable nitroxide radical 2,2,6,6-tetramethyl-4-hydroxy-piperidin-1-oxyl (TEMPOL) has been applied as a sensor to study magnetite nanoparticles both in water suspension and in dried gelatin films. g-values and line widths of ESR spectra of the probe were found to be sensitive to the local magnetic fields of magnetic nanoparticles. Calculated on the basis of the sensor ESR spectra, local magnetic fields are stipulated by linear aggregates of magnetite nanoparticles formed in applied outer magnetic fields and are significantly lower than local magnetic fields estimated from the static magnetic measurements data.

Kovarski, Alexander L.; Sorokina, Olga N.

2007-04-01

153

Magnetic multicore nanoparticles for hyperthermia—influence of particle immobilization in tumour tissue on magnetic properties  

NASA Astrophysics Data System (ADS)

When using magnetic nanoparticles as a heating source for magnetic particle hyperthermia it is of particular interest to know if the particles are free to move in the interstitial fluid or are fixed to the tumour tissue. The immobilization state determines the relaxation behaviour of the administered particles and thus their specific heating power. To investigate this behaviour, magnetic multicore nanoparticles were injected into experimentally grown tumours in mice and magnetic heating treatment was carried out in an alternating magnetic field (H = 25 kA m - 1, f = 400 kHz). The tested particles were well suited for magnetic heating treatment as they heated a tumour of about 100 mg by about 22 K within the first 60 s. Upon sacrifice, histological tumour examination showed that the particles form spots in the tissue with a mainly homogeneous particle distribution in these spots. The magnetic ex vivo characterization of the removed tumour tissue gave clear evidence for the immobilization of the particles in the tumour tissue because the particles in the tumour showed the same magnetic behaviour as immobilized particles. Therefore, the particles are not able to rotate and a temperature increase due to Brown relaxation can be neglected. To accurately estimate the heating potential of magnetic materials, the respective environments influencing the nanoparticle mobility status have to be taken into account.

Dutz, Silvio; Kettering, Melanie; Hilger, Ingrid; Müller, Robert; Zeisberger, Matthias

2011-07-01

154

Enhanced Magnetic Properties in Nanoparticle-Filled CNTs  

NASA Astrophysics Data System (ADS)

There has been much interest in magnetic polymer nanocomposites (MPNCs) recently due to potential applications for EMI shielding, tunable EM devices and flexible electronics. In past studies, using ferrite fillers, we have shown MPNCs to be magnetically tunable when passing a microwave signal through films under the influence of an external magnetic field. We extend this study to include nanoparticle-filled multi-walled carbon nanotubes (CNTs) synthesized by CVD. These high-aspect ratio magnetic nanostructures, with tunable anisotropy, are of particular interest in enhancing magnetic and microwave responses in existing MPNCs. CNTs have an average diameter and length of 300nm and 6 ?m, respectively and are partially filled with CoFe2O4 and NiFe2O4 nanoparticles (NPs) (˜ 7nm). When comparing NPs to NP-filled CNTs, TB increases by ˜ 40K and relaxation time, ?0, increases several orders of magnitude, indicating that enclosing NPs in CNTs enhances interparticle interactions. Structural and magnetic characterization were completed using XRD, TEM and Quantum Design PPMS, using VSM and ACMS options.

Stojak, K.; Chandra, S.; Khurshid, H.; Phan, M. H.; Srikanth, H.

2013-03-01

155

Numerical simulation of magnetic nanoparticles targeting in a bifurcation vessel  

NASA Astrophysics Data System (ADS)

Guiding magnetic iron oxide nanoparticles with the help of an external magnetic field to its target is the principle behind the development of super paramagnetic iron oxide nanoparticles (SPIONs) as novel drug delivery vehicles. The present paper is devoted to study on MDT (Magnetic Drug Targeting) technique by particle tracking in the presence of magnetic field in a bifurcation vessel. The blood flow in bifurcation is considered incompressible, unsteady and Newtonian. The flow analysis applies the time dependent, two dimensional, incompressible Navier-Stokes equations for Newtonian fluids. The Lagrangian particle tracking is performed to estimate particle behavior under influence of imposed magnetic field gradients along the bifurcation. According to the results, the magnetic field increased the volume fraction of particle in target region, but in vessels with high Reynolds number, the efficiency of MDT technique is very low. Also the results showed that in the bifurcation vessels with lower angles, wall shear stress is higher and consequently the risk of the vessel wall rupture increases.

Larimi, M. M.; Ramiar, A.; Ranjbar, A. A.

2014-08-01

156

Frequency distribution of the nanoparticle magnetization in the presence of a static as well as a harmonic magnetic field  

PubMed Central

We explore the properties of the signal from magnetic nanoparticles. The nanoparticle signal has been used to generate images in magnetic particle imaging (MPI). MPI promises to be one of the most sensitive methods of imaging small numbers magnetic nanoparticles and therefore shows promise for molecular imaging. The nanoparticle signal is generated with a pure sinusoidal magnetic field that repeatedly saturates the nanoparticles creating harmonics in the induced magnetization that are easily isolated from the driving field. Signal from a selected position is isolated using a static magnetic field to completely saturate all of the particles outside a voxel enabling an image to be formed voxel by voxel. The signal produced by the magnetization of the nanoparticles contains only odd harmonics. However, it is demonstrated experimentally that with the addition of a static magnetic field bias even harmonics are introduced which increase the total signal significantly. Further, the distribution of signal among the harmonics depends on the static bias field so that information might be used to localize the nanoparticle distribution. Finally, the field required to completely saturate nanoparticles can be quite large and theory predicts that the field required is determined by the smallest nanoparticles in the sample. PMID:18561675

Weaver, John B.; Rauwerdink, Adam M.; Sullivan, Charles R.; Baker, Ian

2008-01-01

157

Targeted thrombolysis by using of magnetic mesoporous silica nanoparticles.  

PubMed

Thrombolytics inevitably led to the risk of hemorrhagic complications due to their non-specific plasminogen activation in treatment of thrombosis. The aim of this study was to determine whether a kind of superparamagnetic mesoporous silica nanoparticle with expanded pore size could achieve effectively targeted thrombolysis. The magnetic mesoporous silica nanoparticles (M-MSNs) with the pore size of 6 nm were prepared by method of the surfactant templating on nano magnetic particles. We investigated the feasibility and efficacy of target thrombolysis with the resultant spheres through fibrin agarose plate assay (FAPA) and a dynamic flow system in vitro. It displayed a 30-fold enhancement of urokinase (UK) loading capacity over the particles without mesoporous layer or the magnetic spheres with mesopores of 3.7 nm. A sustained release behavior was observed due to its larger pore size, higher surface area and narrow mesopore channals contrast to non-mesoporous and small mesopore of 3.7 nm controls. Meanwhile, fibrin agarose plate assay revealed that UK/M-MSNs exhibited a more rapid growth rate of thrombolysis even lasting for 3 days. Additionally, flow model test in vitro suggested this kind of nanoparticle complex enhanced the thrombolysis efficacy by 3.5 fold over the same amount of native UK in 30 min. When compared to non-mesoporous and small mesopore controls, it also represented an extremely higher lysis efficiency (ANOVA, P < 0.01) and a shorter reperfusion time (ANOVA, P < 0.001). Such a magnetic mesoporous silica nanoparticle carrier was expected to be further studied for targeted thrombolytic therapy. PMID:22852472

Wang, Mingqi; Zhang, Jixi; Yuan, Ziming; Yang, Wenzhi; Wu, Qiang; Gu, Hongchen

2012-08-01

158

Magnetic states in Fe nanoparticles imaged by off-axis electron holography  

E-print Network

FF3 Magnetic states in Fe nanoparticles imaged by off-axis electron holography By L. Theil Kuhn (1) Dept. of Materials Science and Metallurgy, University of Cambridge, Cambridge, UK Magnetic nanoparticles of a certain size show single domain magnetic properties. In an intermediate regime between single

Dunin-Borkowski, Rafal E.

159

Controlled Assembly of Magnetic Nanoparticles from Magnetotactic Bacteria Using Microelectromagnets Arrays  

Microsoft Academic Search

Controlled assembly of magnetic nanoparticles was demonstrated by manipulating magnetotactic bacteria in a fluid with microelectromagnets. Magnetotactic bacteria synthesize a chain of magnetic nanoparticles inside their bodies. Microelectromagnets, consisting of multiple layers of lithographically patterned conductors, generate versatile magnetic fields on micrometer length scales, allowing sophisticated control of magnetotactic bacteria inside a microfluidic chamber. A single bacterium was stably trapped

Hakho Lee; Alfreda M. Purdon; Vincent Chu; Robert M. Westervelt

2004-01-01

160

Critical enhancements of MRI contrast and hyperthermic effects by dopant-controlled magnetic nanoparticles.  

PubMed

Doped up: The incorporation of Zn(2+) dopants in tetrahedral sites leads to the successful magnetism tuning of spinel metal ferrite nanoparticles (see picture). (Zn(0.4)Mn(0.6))Fe(2)O(4) nanoparticles exhibit the highest magnetization value among the metal ferrite nanoparticles. Such high magnetism results in the largest MRI contrast effects (r2=860 mm(-1) s(-1)) reported to date and also huge hyperthermic effects. PMID:19137514

Jang, Jung-tak; Nah, Hyunsoo; Lee, Jae-Hyun; Moon, Seung Ho; Kim, Min Gyu; Cheon, Jinwoo

2009-01-01

161

Magnetic Nanoparticles in MR Imaging and Drug Delivery  

PubMed Central

Magnetic nanoparticles (MNPs) possess unique magnetic properties and the ability to function at the cellular and molecular level of biological interactions making them an attractive platform as contrast agents for magnetic resonance imaging (MRI) and as carriers for drug delivery. Recent advances in nanotechnology have improved the ability to specifically tailor the features and properties of MNPs for these biomedical applications. To better address specific clinical needs, MNPs with higher magnetic moments, non-fouling surfaces, and increased functionalities are now being developed for applications in the detection, diagnosis, and treatment of malignant tumors, cardiovascular disease, and neurological disease. Through the incorporation of highly specific targeting agents and other functional ligands, such as fluorophores and permeation enhancers, the applicability and efficacy of these MNPs have greatly increased. This review provides a background on applications of MNPs as MR imaging contrast agents and as carriers for drug delivery and an overview of the recent developments in this area of research. PMID:18558452

Sun, Conroy; Lee, Jerry S.H.; Zhang, Miqin

2009-01-01

162

Optimizing magnetite nanoparticles for mass sensitivity in magnetic particle imaging  

PubMed Central

Purpose: Magnetic particle imaging (MPI), using magnetite nanoparticles (MNPs) as tracer material, shows great promise as a platform for fast tomographic imaging. To date, the magnetic properties of MNPs used in imaging have not been optimized. As nanoparticle magnetism shows strong size dependence, the authors explore how varying MNP size impacts imaging performance in order to determine optimal MNP characteristics for MPI at any driving field frequency f0. Methods: Monodisperse MNPs of varying size were synthesized and their magnetic properties characterized. Their MPI response was measured experimentally using a custom-built MPI transceiver designed to detect the third harmonic of MNP magnetization. The driving field amplitude H0=6 mT ?0?1 and frequency f0=250 kHz were chosen to be suitable for imaging small animals. Experimental results were interpreted using a model of dynamic MNP magnetization that is based on the Langevin theory of superparamagnetism and accounts for sample size distribution and size-dependent magnetic relaxation. Results: The experimental results show a clear variation in the MPI signal intensity as a function of MNP diameter that is in agreement with simulated results. A maximum in the plot of MPI signal vs MNP size indicates there is a particular size that is optimal for the chosen f0. Conclusions: The authors observed that MNPs 15 nm in diameter generate maximum signal amplitude in MPI experiments at 250 kHz. The authors expect the physical basis for this result, the change in magnetic relaxation with MNP size, will impact MPI under other experimental conditions. PMID:21520874

Ferguson, R. Matthew; Minard, Kevin R.; Khandhar, Amit P.; Krishnan, Kannan M.

2011-01-01

163

Magnetic nanoparticles colourization by a mixing-frequency method  

NASA Astrophysics Data System (ADS)

Brownian and Néel relaxation of magnetic nanoparticles (MNPs) can be characterized by a highly sensitive mixing-frequency method using a search-coil based detection system. The unique magnetic properties of MNPs have been used for biomarkers detection. In this paper, we present a theory and implement an experimental detection scheme using the mixing-frequency method to identify different MNPs simultaneously. A low-frequency sinusoidal magnetic field is applied to saturate the MNPs periodically. A high-frequency sinusoidal magnetic field is then applied to generate mixing-frequency signals that are highly specific to the magnetization of MNPs. The spectra of each MNP can be defined as the complex magnetization of the MNPs over the field frequency. The magnetic spectra of various MNPs and magnetic beads have been characterized and compared. The differences between the MNPs spectra enable us to identify the individual MNPs at the same time. A test has been done to verify the ratio of two different MNPs in mixed samples based on the proposed theory. The experimental results show that the mixing-frequency method is a promising method for MNPs colourization.

Tu, Liang; Wu, Kai; Klein, Todd; Wang, Jian-Ping

2014-04-01

164

Magnetic semiconductor and metal-semiconductor junction by Fen nanoparticles encapsulated in beryllium oxygen nanotube  

NASA Astrophysics Data System (ADS)

By using first-principles calculations within the density function theory, the structural, electronic and magnetic properties of BeO nanotube filled with Fen nanoparticles are investigated. We found that all these Fen nanoparticle@BeONTs systems are ferromagnetic (FM) and a spin splitting between spin up and down electrons is observed. In terms of nanoparticle diameter, the Fen nanoparticle@BeONT system could be a semiconductor, half-metal or metal. Also the BeONT locally become non-magnetic semiconductor/magnetic semiconductor junctions or non-magnetic semiconductor/magnetic metal junctions in terms of nanoparticle diameter. The high magnetic moment and spin polarization of the Fen@BeONTs systems imply that it can be used as heterojunctions in electronic devices, magnetic recording, spintronics and are vital for the fabrication of robust nanotube-metal composite materials.

Moradian, Rostam; Shahrokhi, Masoud; Karami Pourian, Aazam

2013-10-01

165

Magnetic polystyrene nanocomposites reinforced with black iron oxide nanoparticles  

NASA Astrophysics Data System (ADS)

Polystyrene (PS)/Fe3O4 nanocomposites with various Fe3O4 particle loadings were synthesized by a solvent extraction method. The dispersion of Fe3O4 nanoparticles (NPs) and the morphology of the PS/Fe3O4 nanocomposites were characterized by the scanning electron microscope (SEM). The effects of the Fe3O4 NPs on the crystallization of PS were also studied by X-ray diffraction (XRD). Fourier transform infrared (FT-IR) spectroscopy analysis indicated a physical entanglement rather than chemical bonding between the NPs and the PS matrix. The thermal properties of the PS/Fe3O 4 nanocomposites were characterized by a thermogravimetic analyzer (TGA) and differential scanning calorimeter (DSC). High thermal stability was observed after introducing the nanoparticles into the polymer matrix. The effects of nanoparticle loading and temperature on the storage/loss modulus of the PS/Fe 3O4 nanocomposites were studied systematically. The mechanical, magnetic, dielectric, and flame retardant properties were studied as well. The glass transition temperature (Tg) of the PS/Fe3O4 nanocomposites has shifted to the higher temperature in the dynamic mechanical analysis (DMA) compared with that of the pure PS. Enhanced dielectric and flame retardant properties of the PS/Fe3O4 nanocomposites were related to the Fe3O4 nanoparticle loadings. The PS/Fe3O4 PNCs exhibit superparamagnetic behavior at room temperature.

Yan, Xingru

166

Labeled magnetic nanoparticles assembly on polypyrrole film for biosensor applications.  

PubMed

In recent years, conducting polymers combined with metallic nanoparticles have been paid more attention due to their potential applications in microelectronics, microsystems, optical sensors and photoelectronic chemistry. The work presented in this paper describes the preparation and characterization of a nanocomposite composed by a thin polypyrrole (PPy) film covered with an assembly of magnetic nanoparticles (NPs). The magnetic particles were immobilized on PPy films under appropriate magnetic field in order to control their organization on the PPy film and finally to improve the sensitivity of the system in potential sensing applications. The electrical properties and morphology of the resulting PPy film and the PPy film/NPs composite were characterized with cyclic voltammetry, impedance spectroscopy (IS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and infra-red spectroscopy (IR). By using streptavidin labeled magnetic particles it was possible to functionalize the NPs assembly with biotin-Fab fragment K47 antibody. The designed biosensor had been successfully applied in rapid, simple, and accurate measurements of atrazine concentrations, with a significantly low detection limit of 5 ng/ml. PMID:18585140

Fredj, H Ben; Helali, S; Esseghaier, C; Vonna, L; Vidal, L; Abdelghani, A

2008-05-15

167

Magnetic nanoparticle hyperthermia: Predictive model for temperature distribution  

PubMed Central

Magnetic nanoparticle (mNP) hyperthermia is a promising adjuvant cancer therapy. mNP’s are delivered intravenously or directly into a tumor, and excited by applying an alternating magnetic field (AMF). The mNP’s are, in many cases, sequestered by cells and packed into endosomes. The proximity of the mNP’s has a strong influence on their ability to heat due to inter-particle magnetic interaction effects. This is an important point to take into account when modeling the mNP’s. Generally, more mNP heating can be achieved using higher magnetic field strengths. The factor which limits the maximum field strength applied to clinically relevant volumes of tissue is the heating caused by eddy currents, which are induced in the noncancerous tissue. A coupled electromagnetic and thermal model has been developed to predict dynamic thermal distributions during AMF treatment. The EM model is based on the method of auxiliary sources and the thermal modeling is based on the Pennes bioheat equation. The results of our phantom study are used to validate the model which takes into account nanoparticle heating, interaction effects, particle spatial distribution, particle size distribution, EM field distribution, and eddy current generation in a controlled environment. Preliminary in vivo data for model validation are also presented. Once fully developed and validated, the model will have applications in experimental design, AMF coil design, and treatment planning.

Stigliano, Robert V.; Shubitidze, Fridon; Petryk, Alicia A.; Tate, Jennifer A.; Hoopes, P. Jack

2014-01-01

168

Magnetic nanoparticle hyperthermia: predictive model for temperature distribution  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticle (mNP) hyperthermia is a promising adjuvant cancer therapy. mNP's are delivered intravenously or directly into a tumor, and excited by applying an alternating magnetic field (AMF). The mNP's are, in many cases, sequestered by cells and packed into endosomes. The proximity of the mNP's has a strong influence on their ability to heat due to inter-particle magnetic interaction effects. This is an important point to take into account when modeling the mNP's. Generally, more mNP heating can be achieved using higher magnetic field strengths. The factor which limits the maximum field strength applied to clinically relevant volumes of tissue is the heating caused by eddy currents, which are induced in the noncancerous tissue. A coupled electromagnetic and thermal model has been developed to predict dynamic thermal distributions during AMF treatment. The EM model is based on the method of auxiliary sources and the thermal modeling is based on the Pennes bioheat equation. The results of our phantom study are used to validate the model which takes into account nanoparticle heating, interaction effects, particle spatial distribution, particle size distribution, EM field distribution, and eddy current generation in a controlled environment. Preliminary in vivo data for model validation are also presented. Once fully developed and validated, the model will have applications in experimental design, AMF coil design, and treatment planning.

Stigliano, Robert V.; Shubitidze, Fridon; Petryk, Alicia A.; Tate, Jennifer A.; Hoopes, P. Jack

2013-02-01

169

Metal nanoparticle fluids with magnetically induced electrical switching properties  

NASA Astrophysics Data System (ADS)

We report the successful preparation of solvent-free metal nanoparticle (NP) fluids with multiple-functionalities, such as rheological properties, magnetism, ionic conductivity, and electrical properties, allowing for facile synthesis and mass production. The gold nanoparticles (AuNPs) used in this study were synthesized using tetraoctylammonium bromide (TOABr) in toluene and then directly phase-transferred to solvent-free low-molecular-weight (Mw) imidazolium-type ionic liquid media containing thiol groups (i.e., IL-SH). Magnetic metal fluids (i.e., MIL-SH-AuNPs) were prepared by the addition of FeCl3 powder to metal fluids (i.e., IL-SH-AuNPs). These fluids showed relatively high ionic and electrical conductivities compared with those of conventional metal NP fluids based on organic ILs with high Mw. Furthermore, it was demonstrated that these fluids could be used as electric switches operated using an external magnetic field in organic media.We report the successful preparation of solvent-free metal nanoparticle (NP) fluids with multiple-functionalities, such as rheological properties, magnetism, ionic conductivity, and electrical properties, allowing for facile synthesis and mass production. The gold nanoparticles (AuNPs) used in this study were synthesized using tetraoctylammonium bromide (TOABr) in toluene and then directly phase-transferred to solvent-free low-molecular-weight (Mw) imidazolium-type ionic liquid media containing thiol groups (i.e., IL-SH). Magnetic metal fluids (i.e., MIL-SH-AuNPs) were prepared by the addition of FeCl3 powder to metal fluids (i.e., IL-SH-AuNPs). These fluids showed relatively high ionic and electrical conductivities compared with those of conventional metal NP fluids based on organic ILs with high Mw. Furthermore, it was demonstrated that these fluids could be used as electric switches operated using an external magnetic field in organic media. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00653k

Kim, Younghoon; Cho, Jinhan

2013-05-01

170

Biocompatible high-moment FeCo-Au magnetic nanoparticles for magnetic hyperthermia treatment optimization  

Microsoft Academic Search

A great deal of attention has been paid to the use of magnetite nanoparticles as heating elements in the research of magnetic fluid hyperthermia. However, these particles have a relatively low magnetization and as a result, have low heating efficiency as well as difficulties in detection applications. To maximize heating efficiency we propose and show the use of high-moment Fe(Co)–Au

Timothy L. Kline; Yun-Hao Xu; Ying Jing; Jian-Ping Wang

2009-01-01

171

Synthesis and characterization of noscapine loaded magnetic polymeric nanoparticles.  

PubMed

The delivery of noscapine therapies directly to the site of the tumor would ultimately allow higher concentrations of the drug to be delivered, and prolong circulation time in vivo to enhance the therapeutic outcome of this drug. Therefore, we sought to design magnetic based polymeric nanoparticles for the site directed delivery of noscapine to invasive tumors. We synthesized Fe(3)O(4) nanoparticles with an average size of 10 ± 2.5 nm. These Fe(3)O(4) NPs were used to prepare noscapine loaded magnetic polymeric nanoparticles (NMNP) with an average size of 252 ± 6.3 nm. Fourier transform infrared (FT-IR) spectroscopy showed the encapsulation of noscapine on the surface of the polymer matrix. The encapsulation of the Fe(3)O(4) NPs on the surface of the polymer was confirmed by elemental analysis. We studied the drug loading efficiency of polylactide acid (PLLA) and poly (L-lactide acid-co-gylocolide) (PLGA) polymeric systems of various molecular weights. Our findings revealed that the molecular weight of the polymer plays a crucial role in the capacity of the drug loading on the polymer surface. Using a constant amount of polymer and Fe(3)O(4) NPs, both PLLA and PLGA at lower molecule weights showed higher loading efficiencies for the drug on their surfaces. PMID:20161408

Abdalla, Mohamed O; Aneja, Ritu; Dean, Derrick; Rangari, Vijay; Russell, Albert; Jaynes, Jessie; Yates, Clayton; Turner, Timothy

2010-01-01

172

Synthesis and characterization of noscapine loaded magnetic polymeric nanoparticles  

PubMed Central

The delivery of noscapine therapies directly to the site of the tumor would ultimately allow higher concentrations of the drug to be delivered, and prolong circulation time in vivo to enhance the therapeutic outcome of this drug. Therefore, we sought to design magnetic based polymeric nanoparticles for the site directed delivery of noscapine to invasive tumors. We synthesized Fe3O4 nanoparticles with an average size of 10 ± 2.5 nm. These Fe3O4 NPs were used to prepare noscapine loaded magnetic polymeric nanoparticles (NMNP) with an average size of 252 ± 6.3 nm. Fourier transform infrared (FT-IR) spectroscopy showed the encapsulation of noscapine on the surface of the polymer matrix. The encapsulation of the Fe3O4 NPs on the surface of the polymer was confirmed by elemental analysis. We studied the drug loading efficiency of polylactide acid (PLLA) and poly (L-lactide acid-co-gylocolide) (PLGA) polymeric systems of various molecular weights. Our findings revealed that the molecular weight of the polymer plays a crucial role in the capacity of the drug loading on the polymer surface. Using a constant amount of polymer and Fe3O4 NPs, both PLLA and PLGA at lower molecule weights showed higher loading efficiencies for the drug on their surfaces. PMID:20161408

Abdalla, Mohamed O.; Aneja, Ritu; Dean, Derrick; Rangari, Vijay; Russell, Albert; Jaynes, Jessie; Yates, Clayton; Turner, Timothy

2009-01-01

173

Synthesis and characterization of noscapine loaded magnetic polymeric nanoparticles  

NASA Astrophysics Data System (ADS)

The delivery of noscapine therapies directly to the site of the tumor would ultimately allow higher concentrations of the drug to be delivered, and prolong circulation time in vivo to enhance the therapeutic outcome of this drug. Therefore, we sought to design magnetic based polymeric nanoparticles for the site directed delivery of noscapine to invasive tumors. We synthesized Fe 3O 4 nanoparticles with an average size of 10±2.5 nm. These Fe 3O 4 NPs were used to prepare noscapine loaded magnetic polymeric nanoparticles (NMNP) with an average size of 252±6.3 nm. Fourier transform infrared (FT-IR) spectroscopy showed the encapsulation of noscapine on the surface of the polymer matrix. The encapsulation of the Fe 3O 4 NPs on the surface of the polymer was confirmed by elemental analysis. We studied the drug loading efficiency of polylactide acid (PLLA) and poly (l-lactide acid-co-gylocolide) (PLGA) polymeric systems of various molecular weights. Our findings revealed that the molecular weight of the polymer plays a crucial role in the capacity of the drug loading on the polymer surface. Using a constant amount of polymer and Fe 3O 4 NPs, both PLLA and PLGA at lower molecule weights showed higher loading efficiencies for the drug on their surfaces.

Abdalla, Mohamed O.; Aneja, Ritu; Dean, Derrick; Rangari, Vijay; Russell, Albert; Jaynes, Jessie; Yates, Clayton; Turner, Timothy

2010-01-01

174

Novel Aspects of Magnetic Interactions in a Macroscopic 3D Nanoparticle-Based Crystal  

NASA Astrophysics Data System (ADS)

We report magnetic measurements on a macroscopic three-dimensional fcc array of iron-oxide nanoparticles. We observe typical nanomagnetism for the randomly packed configuration of nanoparticles, including dynamical freezing and superparamagnetism. By contrast, the nanoparticle “atoms” in the fcc configuration that form the crystal exhibit a low coercivity that is weakly temperature dependent with no superparamagnetism up to 400 K.

Kasyutich, O.; Desautels, R. D.; Southern, B. W.; van Lierop, J.

2010-03-01

175

Novel aspects of magnetic interactions in a macroscopic 3D nanoparticle-based crystal.  

PubMed

We report magnetic measurements on a macroscopic three-dimensional fcc array of iron-oxide nanoparticles. We observe typical nanomagnetism for the randomly packed configuration of nanoparticles, including dynamical freezing and superparamagnetism. By contrast, the nanoparticle "atoms" in the fcc configuration that form the crystal exhibit a low coercivity that is weakly temperature dependent with no superparamagnetism up to 400 K. PMID:20366563

Kasyutich, O; Desautels, R D; Southern, B W; van Lierop, J

2010-03-26

176

Electrostatic complexation of polyelectrolyte and magnetic nanoparticles: from wild clustering to controllable magnetic wires  

NASA Astrophysics Data System (ADS)

We present the electrostatic complexation between polyelectrolytes and charged nanoparticles. The nanoparticles in solution are ?-Fe2O3 (maghemite) spheres with 8.3 nm diameter and anionic surface charges. The complexation was monitored using three different formulation pathways such as direct mixing, dilution, and dialysis. In the first process, the hybrids were obtained by mixing stock solutions of polymers and nanoparticles. A `destabilization state' with sharp and intense maximum aggregation was found at charges stoichiometry (isoelectric point). While on the two sides of the isoelectric point, `long-lived stable clusters state' (arrested states) were observed. Dilution and dialysis processes were based on controlled desalting kinetics according to methods developed in molecular biology. Under an external magnetic field ( B = 0.3 T), from dialysis at isoelectric point and at arrested states, cationic polyelectrolytes can `paste' these magnetic nanoparticles (NPs) together to yield irregular aggregates (size of 100 ?m) and regular rod-like aggregates, respectively. These straight magnetic wires were fabricated with diameters around 200 nm and lengths comprised between 1 ?m and 0.5 mm. The wires can have either positive or negative charges on their surface. After analyzing their orientational behavior under an external rotating field, we also showed that the wires made from different polyelectrolytes have the same magnetic property. The recipe used a wide range of polyelectrolytes thereby enhancing the versatility and applied potentialities of the method. This simple and general approach presents significant perspective for the fabrication of hybrid functional materials.

Yan, Minhao; Qu, Li; Fan, Jiangxia; Ren, Yong

2014-05-01

177

Evaluation of hyperthermia of magnetic nanoparticles by dehydrating DNA.  

PubMed

A method based on the thermodynamic equilibrium reached between the hybridization and denaturation of double-stranded DNA (ds-DNA) is opened up to evaluate the hyperthermia performance of magnetic nanoparticles (MNPs). Two kinds of MNPs with different sizes and magnetic performance are chosen, and their temperature increments at the surface area under an alternating magnetic field (AMF) are calculated and compared through the concentration variation of ds-DNA modified on the surface. The temperature difference between the surface area of MNPs and bulk solution is also investigated, which can reach as high as 57.8°C when AMF applied for 300?s. This method provides a direct path way of comparison hyperthermia ability of MNPs, and serves as a good reference to choose MNPs and decides the therapy parameters based on the unique drug response of individual patient. PMID:25427561

Yu, Lina; Liu, Jinming; Wu, Kai; Klein, Todd; Jiang, Yong; Wang, Jian-Ping

2014-01-01

178

Superparamagnetic nanoparticle detection using second harmonic of magnetization response  

NASA Astrophysics Data System (ADS)

We introduce a method to improve the detection sensitivity for the magnetization M of superparamagnetic nanoparticles (MNP). The M response of MNP to an applied magnetic field H (M-H characteristics) could be divided into a linear region and a saturation region, which are separated at a transition point Hk. When applying an excitation magnetic field (Hac) with a frequency ?0 and an additional dc bias field Hdc = Hk, the second harmonic of M reaches the maximum due to the nonlinearity of the M-H characteristics. It is stronger than any other harmonics and responsible for small Hac without a threshold. The second harmonic selected as the readout criterion for M response of MNP is systematically analyzed and experimentally proven.

Zhang, Yi; Murata, Hayaki; Hatsukade, Yoshimi; Tanaka, Saburo

2013-09-01

179

Magnetic Iron Oxide Nanoparticles: Synthesis and Surface Functionalization Strategies  

PubMed Central

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

2008-01-01

180

Improved delivery of magnetic nanoparticles with chemotherapy cancer treatment  

PubMed Central

Most nanoparticle-based cancer therapeutic strategies seek to develop an effective individual cancer cell or metastatic tumor treatment. Critical to the success of these therapies is to direct as much of the agent as possible to the targeted tissue while avoiding unacceptable normal tissue complications. In this light, three different cisplatinum/magnetic nanoparticle (mNP) administration regimens were investigated. The most important finding suggests that clinically relevant doses of cisplatinum result in a significant increase in the tumor uptake of systemically delivered mNP. This enhancement of mNP tumor uptake creates the potential for an even greater therapeutic ratio through the addition of mNP based, intracellular hyperthermia. PMID:25301996

Petryk, Alicia A.; Giustini, Andrew J.; Gottesman, Rachel E.; Hoopes, P. Jack

2014-01-01

181

Improved delivery of magnetic nanoparticles with chemotherapy cancer treatment  

NASA Astrophysics Data System (ADS)

Most nanoparticle-based cancer therapeutic strategies seek to develop an effective individual cancer cell or metastatic tumor treatment. Critical to the success of these therapies is to direct as much of the agent as possible to the targeted tissue while avoiding unacceptable normal tissue complications. In this light, three different cisplatinum/magnetic nanoparticle (mNP) administration regimens were investigated. The most important finding suggests that clinically relevant doses of cisplatinum result in a significant increase in the tumor uptake of systemically delivered mNP. This enhancement of mNP tumor uptake creates the potential for an even greater therapeutic ratio through the addition of mNP based, intracellular hyperthermia.

Petryk, Alicia A.; Giustini, Andrew J.; Gottesman, Rachel E.; Hoopes, P. Jack

2013-02-01

182

Stabilisation effects of superparamagnetic nanoparticles on clustering in nanocomposite microparticles and on magnetic behaviour  

NASA Astrophysics Data System (ADS)

Superparamagnetic nanoparticles of magnetite were coprecipitated from iron salts, dispersed with nitric acid and stabilised either by lactic acid (LA) or by a polycarboxylate-ether polymer (MELPERS4343, MP). The differently stabilised nanoparticles were incorporated into a silica matrix to form nanocomposite microparticles. The silica matrix was prepared either from tetraethylorthosilicate (TEOS) or from an aqueous sodium silicate (water glass) solution. Stabilisation of nanoparticles had a crucial influence on microparticle texture and nanoparticle distribution in the silica matrix. Magnetic measurements in combination with transmission electron microscopy (TEM) investigations suggest a uniform magnetic interaction of nanoparticles in case of LA stabilisation and magnetically interacting nanoparticle clusters of different sizes in case of MP stabilisation. Splitting of blocking temperature (TB) and irreversible temperature (Tir) in zero field cooled (ZFC) and field cooled (FC) measurements is discussed in terms of nanoparticle clustering.

Mandel, K.; Hutter, F.; Gellermann, C.; Sextl, G.

2013-04-01

183

Influence of spherical assembly of copper ferrite nanoparticles on magnetic properties: orientation of magnetic easy axis.  

PubMed

The magnetic properties of copper ferrite (CuFe2O4) nanoparticles prepared via sol-gel auto combustion and facile solvothermal method are studied focusing on the effect of nanoparticle arrangement. Randomly oriented CuFe2O4 nanoparticles (NP) are obtained from the sol-gel auto combustion method, while the solvothermal method allows us to prepare iso-oriented uniform spherical ensembles of CuFe2O4 nanoparticles (NS). X-ray diffractometry (XRD), atomic absorption spectroscopy (AAS), infra-red (IR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), (57)Fe Mössbauer spectroscopy and vibrating sample magnetometer (VSM) are used to investigate the composition, microstructure and magnetic properties of as-prepared ferrite nanoparticles. The field-dependent magnetization measurement for the NS sample at low temperature exhibits a step-like rectangular hysteresis loop (M(R)/M(S) ~ 1), suggesting cubic anisotropy in the system, whereas for the NP sample, typical features of uniaxial anisotropy (M(R)/M(S) ~ 0.5) are observed. The coercive field (HC) for the NS sample shows anomalous temperature dependence, which is correlated with the variation of effective anisotropy (K(E)) of the system. A high-temperature enhancement of H(C) and K(E) for the NS sample coincides with a strong spin-orbit coupling in the sample as evidenced by significant modification of Cu/Fe-O bond distances. The spherical arrangement of nanocrystals at mesoscopic scale provokes a high degree of alignment of the magnetic easy axis along the applied field leading to a step-like rectangular hysteresis loop. A detailed study on the temperature dependence of magnetic anisotropy of the system is carried out, emphasizing the influence of the formation of spherical iso-oriented assemblies. PMID:24714977

Chatterjee, Biplab K; Bhattacharjee, Kaustav; Dey, Abhishek; Ghosh, Chandan K; Chattopadhyay, Kalyan K

2014-06-01

184

Enhanced magnetic resonance contrast of iron oxide nanoparticles embedded in a porous silicon nanoparticle host  

NASA Astrophysics Data System (ADS)

In this report, we prepared a porous Si nanoparticle with a pore morphology that facilitates the proximal loading and alignment of magnetite nanoparticles. We characterized the composite materials using superconducting quantum interference device magnetometry, dynamic light scattering, transmission electron microscopy, and MRI. The in vitro cytotoxicity of the composite materials was tested using cell viability assays on human liver cancer cells and rat hepatocytes. An in vivo analysis using a hepatocellular carcinoma (HCC) Sprague Dawley rat model was used to determine the biodistribution properties of the material, while naïve Sprague Dawley rats were used to determine the pharmocokinetic properties of the nanomaterials. The composite material reported here demonstrates an injectable nanomaterial that exploits the dipolar coupling of superparamagnetic nanoparticles trapped within a secondary inorganic matrix to yield significantly enhanced MRI contrast. This preparation successfully avoids agglomeration issues that plague larger ferromagnetic systems. A Fe3O4:pSi composite formulation consisting of 25% by mass Fe3O4 yields an maximal T2* value of 556 mM Fe-1 s-1. No cellular (HepG2 or rat hepatocyte cells) or in vivo (rat) toxicity was observed with the formulation, which degrades and is eliminated after 4-8 h in vivo. The ability to tailor the magnetic properties of such materials may be useful for in vivo imaging, magnetic hyperthermia, or drug-delivery applications.

Kinsella, Joseph; Ananda, Shalini; Andrew, Jennifer; Grondek, Joel; Chien, Miao-Ping; Scandeng, Miriam; Gianneschi, Nathan; Ruoslahti, Erkki; Sailor, Michael

2013-02-01

185

Preparation and application of magnetic Fe 3O 4 nanoparticles for wastewater purification  

Microsoft Academic Search

Fe3O4 magnetic nanoparticles with different average sizes were synthesized and structural characterizations showed that the three kinds of nanoparticles had different sizes, i.e., an average particle size of 8nm, 12nm and 35nm was observed for the nanoparticles prepared with the co-precipitation method, the co-precipitation combining a surface decoration process, and the polyol process, respectively. The synthesized Fe3O4 nanoparticles with different

Y. F. Shen; J. Tang; Z. H. Nie; Y. D. Wang; Y. Ren; L. Zuo

2009-01-01

186

Investigation of magnetic properties of Fe3O4 nanoparticles using temperature dependent magnetic hyperthermia in ferrofluids  

NASA Astrophysics Data System (ADS)

Rate of heat generated by magnetic nanoparticles in a ferrofluid is affected by their magnetic properties, temperature, and viscosity of the carrier liquid. We have investigated temperature dependent magnetic hyperthermia in ferrofluids, consisting of dextran coated superparamagnetic Fe3O4 nanoparticles, subjected to external magnetic fields of various frequencies (188-375 kHz) and amplitudes (140-235 Oe). Transmission electron microscopy measurements show that the nanoparticles are polydispersed with a mean diameter of 13.8 ± 3.1 nm. The fitting of experimental dc magnetization data to a standard Langevin function incorporating particle size distribution yields a mean diameter of 10.6 ± 1.2 nm, and a reduced saturation magnetization (˜65 emu/g) compared to the bulk value of Fe3O4 (˜95 emu/g). This is due to the presence of a finite surface layer (˜1 nm thickness) of non-aligned spins surrounding the ferromagnetically aligned Fe3O4 core. We found the specific absorption rate, measured as power absorbed per gram of iron oxide nanoparticles, decreases monotonically with increasing temperature for all values of magnetic field and frequency. Using the size distribution of magnetic nanoparticles estimated from the magnetization measurements, we have fitted the specific absorption rate versus temperature data using a linear response theory and relaxation dissipation mechanisms to determine the value of magnetic anisotropy constant (28 ± 2 kJ/m3) of Fe3O4 nanoparticles.

Nemala, H.; Thakur, J. S.; Naik, V. M.; Vaishnava, P. P.; Lawes, G.; Naik, R.

2014-07-01

187

Structural characterization and magnetic properties of superparamagnetic zinc ferrite nanoparticles synthesized by the coprecipitation method  

NASA Astrophysics Data System (ADS)

Single phase zinc ferrite (ZnFe2O4) nanoparticles have been prepared by the coprecipitation method without any subsequent calcination. The effects of precipitation temperature in the range 20-80 °C on the structural and the magnetic properties of zinc ferrite nanoparticles were investigated. The crystallite size, microstructure and magnetic properties of the prepared nanoparticles were studied using X-ray diffraction (XRD), Fourier transmission infrared spectrum, transmission electron microscope (TEM), energy dispersive X-ray spectrometer and vibrating sample magnetometer. The XRD results showed that the coprecipitated nanoparticles were single phase zinc ferrite with mixture of normal and inverse spinel structures. Furthermore, ZnFe2O4 nanoparticles have the crystallite size in the range 5-10 nm, as confirmed by TEM. The magnetic measurements exhibited that the zinc ferrite nanoparticles synthesized at 40 °C were superparamagnetic with the maximum magnetization of 7.3 emu/g at 10 kOe.

Raeisi Shahraki, R.; Ebrahimi, M.; Seyyed Ebrahimi, S. A.; Masoudpanah, S. M.

2012-11-01

188

MR imaging of Her-2/neu protein using magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

The aim of this study was to assess whether Her-2/neu expressing tumour cells can be detected in vitro as well as in animal tumour models with magnetic resonance imaging at 1.5 T. Magnetic nanoparticles (with relaxivities R 1, R 2 of 3.7 ± 0.4 (mM s)-1, 277 ± 32 (mM s)-1 at 21 °C, respectively) coupled to anti-Her-2/neu antibodies or gamma globulin IgG (high or non-affinity probe, respectively) were used. After incubation of Her-2/neu expressing cells (SKBR3) with high or non-affinity probes (20 min), values of R 1 = 0.34 ± 0.02 (mM s)-1 and R 2 = 63.02 ± 30 (mM s)-1 were obtained. Electron microscopy and atomic absorption spectrometry examinations verified the presence of relatively high iron levels in cells incubated with the high affinity probe compared to controls. For in vivo MRI, high or non-affinity probes (ap1.7 mg Fe/animal) were injected into the tail vein of mice (n = 16) bearing SKBR3 tumours. A distinct decrease in the normalized MR signal ratio between tumour and reference area (approximately -17 ± 2%) after application of the high affinity probe was observed. In conclusion, in vivo detection of Her-2/neu expressing tumours is feasible in a clinical MR scanner by using immunoconjugated magnetic nanoparticles.

Hilger, Ingrid; Trost, René; Reichenbach, Jürgen R.; Linß, Werner; Lisy, Marcus-René; Berndt, Alexander; Kaiser, Werner A.

2007-04-01

189

Monodisperse magnetite nanoparticle tracers for in vivo magnetic particle imaging  

PubMed Central

Magnetic Particle Imaging (MPI) is a new biomedical imaging modality that produces real-time, high-resolution tomographic images of superparamagnetic iron oxide (SPIO) nanoparticle tracer distributions. In this study, we synthesized monodisperse tracers for enhanced MPI performance and investigated both, their blood clearance time using a 25 kHz magnetic particle spectrometer (MPS), and biodistribution using a combination of quantitative T2-weighted MRI and tissue histology. In vitro and in vivo MPI performance of our magnetic nanoparticle tracers (MNTs), subject to biological constraints, were compared to commercially available SPIOs (Resovist). Monodisperse MNTs showed a 2-fold greater signal per unit mass, and 20% better spatial resolution. In vitro evaluation of tracers showed that MPI performance of our MNTs is preserved in blood, serum-rich cell culture medium and gel; thus independent of changes in hydrodynamic volume and fluid viscosity – a critical prerequisite for in vivo MPI. In a rodent model, our MNTs circulated for 15 minutes – 3× longer than Resovist – and supported our in vitro evaluation that MPI signal is preserved in the physiological environment. Furthermore, MRI and histology analysis showed that MNTs distribute in the reticuloendothelial system (RES) in a manner similar to clinically approved SPIO agents. MNTs demonstrating long-circulation times and optimized MPI performance show potential as angiography tracers and blood-pool agents for the emerging MPI imaging modality. PMID:23434348

Khandhar, Amit P; Ferguson, R Matthew; Arami, Hamed; Krishnan, Kannan M

2013-01-01

190

Detection of Magnetic Nanoparticles with Superconducting Quantum Interference Device (SQUID) Magnetometer and Application to Immunoassays  

Microsoft Academic Search

A system is developed to magnetically measure biological antigen-antibody reactions with a superconducting quantum interference device (SQUID) magnetometer. In this system, antibodies are labeled with magnetic nanoparticles of gamma-Fe2O3, and the antigen-antibody reactions are measured by detecting the magnetic field from the magnetic nanoparticles. A setup of the system is described, and the sensitivity of the system is studied in

Keiji Enpuku; Tadashi Minotani; Takemitsu Gima; Yukinori Kuroki; Yuzuru Itoh; Makiko Yamashita; Yoshinori Katakura; Satoru Kuhara

1999-01-01

191

Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields  

NASA Astrophysics Data System (ADS)

When a micron-sized magnetizable particle is introduced into a suspension of nanosized magnetic particles, the nanoparticles accumulate around the microparticle and form thick anisotropic clouds extended in the direction of the applied magnetic field. This phenomenon promotes colloidal stabilization of bimodal magnetic suspensions and allows efficient magnetic separation of nanoparticles used in bioanalysis and water purification. In the present work, the size and shape of nanoparticle clouds under the simultaneous action of an external uniform magnetic field and the flow have been studied in detail. In experiments, a dilute suspension of iron oxide nanoclusters (of a mean diameter of 60 nm) was pushed through a thin slit channel with the nickel microspheres (of a mean diameter of 50 ?m) attached to the channel wall. The behavior of nanocluster clouds was observed in the steady state using an optical microscope. In the presence of strong enough flow, the size of the clouds monotonically decreases with increasing flow speed in both longitudinal and transverse magnetic fields. This is qualitatively explained by enhancement of hydrodynamic forces washing the nanoclusters away from the clouds. In the longitudinal field, the flow induces asymmetry of the front and the back clouds. To explain the flow and the field effects on the clouds, we have developed a simple model based on the balance of the stresses and particle fluxes on the cloud surface. This model, applied to the case of the magnetic field parallel to the flow, captures reasonably well the flow effect on the size and shape of the cloud and reveals that the only dimensionless parameter governing the cloud size is the ratio of hydrodynamic-to-magnetic forces—the Mason number. At strong magnetic interactions considered in the present work (dipolar coupling parameter ? ?2), the Brownian motion seems not to affect the cloud behavior.

Magnet, C.; Kuzhir, P.; Bossis, G.; Meunier, A.; Nave, S.; Zubarev, A.; Lomenech, C.; Bashtovoi, V.

2014-03-01

192

Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields  

E-print Network

When a micron-sized magnetizable particle is introduced into a suspension of nanosized magnetic particles, the nanoparticles accumulate around the microparticle and form thick anisotropic clouds extended in the direction of the applied magnetic field. This phenomenon promotes colloidal stabilization of bimodal magnetic suspensions and allows efficient magnetic separation of nanoparticles used in bioanalysis and water purification. In the present work, size and shape of nanoparticle clouds under the simultaneous action of an external uniform magnetic field and the flow have been studied in details. In experiments, dilute suspension of iron oxide nanoclusters (of a mean diameter of 60 nm) was pushed through a thin slit channel with the nickel microspheres (of a mean diameter of 50$\\mu$m) attached to the channel wall. The behavior of nanocluster clouds was observed in the steady state using an optical microscope. In the presence of strong enough flow, the size of the clouds monotonically decreases with increasing flow speed in both longitudinal and transverse magnetic fields. This is qualitatively explained by enhancement of hydrodynamic forces washing the nanoclusters away from the clouds. In the longitudinal field, the flow induces asymmetry of the front and the back clouds. To explain the flow and the field effects on the clouds, we have developed a simple model based on the balance of the stresses and particle fluxes on the cloud surface. This model, applied to the case of the magnetic field parallel to the flow, captures reasonably well the flow effect on the size and shape of the cloud and reveals that the only dimensionless parameter governing the cloud size is the ratio of hydrodynamic-to-magnetic forces - the Mason number. At strong magnetic interactions considered in the present work (dipolar coupling parameter $\\alpha \\geq 2$), the Brownian motion seems not to affect the cloud behavior.

Cécilia Magnet; Pavel Kuzhir; Georges Bossis; Alain Meunier; Sebastien Nave; Andrey Zubarev; Claire Lomenech; Victor Bashtovoi

2014-04-14

193

A direct competitive enzyme-linked immunosorbent assay by antibody coated for diethyl phthalate analysis.  

PubMed

A direct competitive enzyme-linked immunosorbent assay (ELISA) has been developed for detection of diethyl phthalate (DEP). Protein-hapten conjugate was synthesized to produce polyclonal antibodies against DEP. Experimental parameters were optimized, including immunoreaction conditions, the dilution ratio of horseradish peroxidase (HRP)-antigen conjugate, time of the antibody coated, effect of pH, and ionic strength. The limit of detection was 0.096ng/ml, and the linear range was 0.1-3500ng/ml with a regression coefficient (R(2)) of 0.9957. Recoveries were between 96.4 and 106.2%. The cross-reactivities of the anti-DEP antibody to six structurally related phthalate esters were less than 9%. The method was successfully applied to the determination of DEP in tap water, river water (Yangtze River), and leachate from plastic drinking bottles. This immunoassay was highly specific, sensitive, rapid, simple, and suitable for DEP monitoring. The results obtained were compared with those obtained using the high-performance liquid chromatography method. PMID:20599639

Zhang, Mingcui; Cong, Ying; Sheng, Yali; Liu, Bolin

2010-11-01

194

Liver cancer immunoassay with magnetic nanoparticles and MgO-based magnetic tunnel junction sensors  

NASA Astrophysics Data System (ADS)

We have demonstrated the detection of alpha-fetoprotein (AFP) labeled with magnetic nanoparticles (MNPs) using MgO-based magnetic tunnel junction (MTJ) sensors. AFP is an important hepatic tumor biomarker and the detection of AFP has significant applications for clinical diagnostics and immunoassay for early-stage liver cancer indications. In this work, MgO-based MTJ sensors and 20-nm iron-oxide magnetic nanoparticles (MNPs) were used for detecting AFP antigens by a sandwich-assay configuration. The MTJ sensors with a sensing area of 4 × 2 ?m2 possess tunneling magnetoresistance (TMR) of 122% and sensitivity of 0.95%/Oe at room temperature. The target AFP antigens of three concentrations were successfully detected, and the experimental data indicate that the resistance variations of the MTJ sensor increased with the AFP concentration ratios proportionally. These results demonstrate that MgO-based MTJ sensors together with MNPs are a promising biosensing platform for liver cancer immunoassay.

Lei, Z. Q.; Li, L.; Li, G. J.; Leung, C. W.; Shi, J.; Wong, C. M.; Lo, K. C.; Chan, W. K.; Mak, C. S. K.; Chan, S. B.; Chan, N. M. M.; Leung, C. H.; Lai, P. T.; Pong, P. W. T.

2012-04-01

195

Magnetic properties of hematite (?-Fe2O3) nanoparticles prepared by hydrothermal synthesis method  

NASA Astrophysics Data System (ADS)

Hematite (?-Fe2O3) nanoparticles are successfully synthesized by using the hydrothermal synthesis method. An X-ray powder diffraction (XRPD) of the sample shows formation of the nanocrystalline ?-Fe2O3 phase. A transmission electron microscopy (TEM) measurements show spherical morphology of the hematite nanoparticles and narrow size distribution. An average hematite nanoparticle size is estimated to be about 8 nm by TEM and XRD. Magnetic properties were measured using a superconducting quantum interference device (SQUID) magnetometry. Investigation of the magnetic properties of hematite nanoparticles showed a divergence between field-cooled (FC) and zero-field-cooled (ZFC) magnetization curves below Tirr = 103 K (irreversibility temperature). The ZFC magnetization curve showed maximum at TB = 52 K (blocking temperature). The sample did not exhibit the Morin transition. The M(H) (magnetization versus magnetic field) dependence at 300 K showed properties of superparamagnetic iron oxide nanoparticles (SPION). The M(H) data were successfully fitted by the Langevin function and magnetic moment ?p = 657 ?B and diameter d = 8.1 nm were determined. Furthermore, magnetic measurements showed high magnetization at room temperature (MS = 3.98 emu/g), which is desirable for application in spintronics and biomedicine. Core-shell structure of the nanoparticles was used to describe high magnetization of the hematite nanoparticles.

Tadic, Marin; Panjan, Matjaz; Damnjanovic, Vesna; Milosevic, Irena

2014-11-01

196

Multi-functional magnetic nanoparticles for magnetic resonance imaging and cancer therapy.  

PubMed

We have developed a multi-layer approach for the synthesis of water-dispersible superparamagnetic iron oxide nanoparticles for hyperthermia, magnetic resonance imaging (MRI) and drug delivery applications. In this approach, iron oxide core nanoparticles were obtained by precipitation of iron salts in the presence of ammonia and provided ?-cyclodextrin and pluronic polymer (F127) coatings. This formulation (F127250) was highly water dispersible which allowed encapsulation of the anti-cancer drug(s) in ?-cyclodextrin and pluronic polymer for sustained drug release. The F127250 formulation has exhibited superior hyperthermia effects over time under alternating magnetic field compared to pure magnetic nanoparticles (MNP) and ?-cyclodextrin coated nanoparticles (CD200). Additionally, the improved MRI characteristics were also observed for the F127250 formulation in agar gel and in cisplatin resistant ovarian cancer cells (A12780CP) compared to MNP and CD200 formulations. Furthermore, the drug-loaded formulation of F127250 exhibited many folds of imaging contrast properties. Due to the internalization capacity of the F127250 formulation, its curcumin-loaded formulation (F127250-CUR) exhibited almost equivalent inhibition effects on A2780CP (ovarian), MDA-MB-231 (breast), and PC-3 (prostate) cancer cells even though curcumin release was only 40%. The improved therapeutic effects were verified by examining molecular effects using Western blotting and transmission electron microscopic (TEM) studies. F127250-CUR also exhibited haemocompatibility, suggesting a nanochemo-therapeutic agent for cancer therapy. PMID:21167595

Yallapu, Murali M; Othman, Shadi F; Curtis, Evan T; Gupta, Brij K; Jaggi, Meena; Chauhan, Subhash C

2011-03-01

197

Multi-functional Magnetic Nanoparticles for Magnetic Resonance Imaging and Cancer Therapy  

PubMed Central

We have developed a multi-layer approach for the synthesis of water-dispersible superparamagnetic iron oxide nanoparticles for hyperthermia, magnetic resonance imaging (MRI) and drug delivery applications. In this approach, iron oxide core nanoparticles were obtained by precipitation of iron salts in the presence of ammonia and provided ?-cyclodextrin and pluronic polymer (F127) coatings. This formulation (F127250) was highly water dispersible which allowed encapsulation of the anti-cancer drug(s) in ?-cyclodextrin and pluronic polymer for sustained drug release. The F127250 formulation has exhibited superior hyperthermia effects over time under alternating magnetic field compared to pure magnetic nanoparticles (MNP) and ?-cyclodextrin coated nanoparticles (CD200). Additionally, the improved MRI characteristics were also observed for the F127250 formulation in agar gel and in cisplatin resistant ovarian cancer cells (A12780CP) compared to MNP and CD200 formulations. Furthermore, the drug loaded formulation of F127250 exhibited many folds of imaging contrast properties. Due to the internalization capacity of the F127250 formulation, its curcumin loaded formulation (F127250-CUR) exhibited almost equivalent inhibition effects on A2780CP (ovarian), MDA-MB-231 (breast), and PC3 (prostate) cancer cells even though curcumin release was only 40%. The improved therapeutic effects were verified by examining molecular effects using Western blotting and transmission electron microscopic (TEM) studies. F127250-CUR also exhibited haemocompatibility, suggesting a nanochemo-therapuetic agent for cancer therapy. PMID:21167595

Yallapu, Murali M.; Othman, Shadi F.; Curtis, Evan T.; Gupta, Brij K.; Jaggi, Meena; Chauhan, Subhash C.

2010-01-01

198

Fe3O4 magnetic nanoparticles synthesis from tailings by ultrasonic chemical co-precipitation  

E-print Network

Fe3O4 magnetic nanoparticles synthesis from tailings by ultrasonic chemical co-precipitation Shen online xxxx Keywords: Fe3O4 nanoparticles Ultrasonic-assisted chemical co-precipitation Surfaces Magnetic-assisted chemical co- precipitation utilizing high purity iron separated from iron ore tailings by acidic leaching

Volinsky, Alex A.

199

Magnetic agglomeration method for size control in the synthesis of magnetic nanoparticles  

DOEpatents

A method for controlling the size of chemically synthesized magnetic nanoparticles that employs magnetic interaction between particles to control particle size and does not rely on conventional kinetic control of the reaction to control particle size. The particles are caused to reversibly agglomerate and precipitate from solution; the size at which this occurs can be well controlled to provide a very narrow particle size distribution. The size of particles is controllable by the size of the surfactant employed in the process; controlling the size of the surfactant allows magnetic control of the agglomeration and precipitation processes. Agglomeration is used to effectively stop particle growth to provide a very narrow range of particle sizes.

Huber, Dale L. (Albuquerque, NM)

2011-07-05

200

Synthesis, assembly and physical properties of magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Compared with the top-down lithographic techniques, bottom-up chemical synthesis and self-assembly approaches offer much more flexibilities in creating magnetic nanostructures with controlled size, shape, composition and physical properties. This review summarizes some of the latest developments in this field, with emphasis mainly on transition metals, their alloys and metal oxide nanoparticles. The focus is directed towards the conditions of individual particles as well as large assemblies of particles through colloidal chemistry. Furthermore, some of the future directions in nanomagnetism from the perspective of physical chemists is also presented.

Lin, Xiao-Min; Samia, Anna C. S.

2006-10-01

201

Direct dyes removal using modified magnetic ferrite nanoparticle  

PubMed Central

The magnetic adsorbent nanoparticle was modified using cationic surface active agent. Zinc ferrite nanoparticle and cetyl trimethylammonium bromide were used as an adsorbent and a surface active agent, respectively. Dye removal ability of the surface modified nanoparticle as an adsorbent was investigated. Direct Green 6 (DG6), Direct Red 31 (DR31) and Direct Red 23 (DR23) were used. The characteristics of the adsorbent were studied using Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effect of adsorbent dosage, initial dye concentration and salt was evaluated. In ternary system, dye removal of the adsorbent at 90, 120, 150 and 200 mg/L dye concentration was 63, 45, 30 and 23% for DR23, 97, 90, 78 and 45% for DR31 and 51, 48, 42 and 37% for DG6, respectively. It was found that dye adsorption onto the adsorbent followed Langmuir isotherm. The adsorption kinetic of dyes was found to conform to pseudo-second order kinetics. PMID:24991427

2014-01-01

202

Investigation of nanoparticle distribution formed by the rotation of the magnetic system  

NASA Astrophysics Data System (ADS)

An even dispersion of nanoparticles onto a cell monolayer may open up new options for the gene transfer into cells and this could be a valuable achievement in the field of nanotechnology based drug delivery. Here we report on our evaluation of superparamagnetic iron oxide nanoparticle (SPION) patterning formed by magnetic arrays with unipolar NdFeB magnet arrangements and describe a rotating magnetic array as well as underlying mechanisms of the nanoparticle pattern formation. SPION pattern derived from static magnetic array represents line-like pattern, while the pattern formed by orbital magnetic array is homogenously distributed nanoparticles. Our results show that the SPION sedimentation under the time-phase varying action of magnetic field occurs with horizontal motion of nanoparticles and forms a homogenous distribution of them on the target. In the process, the amplitude of nanoparticle displacement reaches up to 0.5 ?m at the magnet boundary, at the greatest linear speed tested of 60 mm/s (magnetic field gradient: 50 T/m). Application of the orbital magnetic array increases the probability of nanoparticle-cell interactions and enhances the efficiency of the gene delivery.

Karpov, Andrej; Kozireva, Svetlana; Avoti?a, Dace; Chernobayeva, Lidija; Baryshev, Mikhail

2014-11-01

203

Scaffold-independent Patterning of Cells using Magnetic Nanoparticles  

NASA Astrophysics Data System (ADS)

Spatial patterning of cells in vitro relies on direct contact of cells on to solid surfaces. Scaffold independent patterning of cells has never been achieved so far. Patterning of cells has wide applications including stem cell biology, tissue architecture and regenerative medicine besides fundamental biology. Magnetized cells in a suspension can be manipulated using an externally applied magnetic field enabling directed patterning. We magnetized mammalian cells by internalization of superparamagnetic nanoparticles coated with bovine serum albumin (BSA). A magnetic field is then used to arrange cells in a desired pattern on a substrate or in suspension. The control strategy is derived from the self-assembly of magnetic colloids in a liquid considering magnetostatic interactions. The range of achievable structural features promise novel experimental methods investigating the influence of tissue shape and size on cell population dynamics wherein Fickian diffusion of autocrine growth signals are known to play a significant role. By eliminating the need for a scaffold, intercellular adhesion mechanics and the effects of temporally regulated signals can be investigated. The findings can be applied to novel tissue engineering methods.

Ghosh, Suvojit; Biswas, Moanaro; Elankumaran, Subbiah; Puri, Ishwar

2013-03-01

204

Magnetic nanoparticles as both imaging probes and therapeutic agents.  

PubMed

Magnetic nanoparticles (MNPs) have been explored extensively as contrast agents for magnetic resonance imaging (MRI) or as heating agents for magnetic fluid hyperthermia (MFH) [1]. To achieve optimum operation conditions in MRI and MFH, these NPs should have well-controlled magnetic properties and biological functionalities. Although numerous efforts have been dedicated to the investigations on MNPs for biomedical applications [2-5], the NP optimizations for early diagnostics and efficient therapeutics are still far from reached. Recent efforts in NP syntheses have led to some promising MNP systems for sensitive MRI and efficient MFH applications. This review summarizes these advances in the synthesis of monodisperse MNPs as both contrast probes in MRI and as therapeutic agents via MFH. It will first introduce the nanomagnetism and elucidate the critical parameters to optimize the superparamagnetic NPs for MRI and ferromagnetic NPs for MFH. It will further outline the new chemistry developed for making monodisperse MNPs with controlled magnetic properties. The review will finally highlight the NP functionalization with biocompatible molecules and biological targeting agents for tumor diagnosis and therapy. PMID:20388109

Lacroix, Lise-Marie; Ho, Don; Sun, Shouheng

2010-01-01

205

Influence of the morphology of ferrite nanoparticles on the directed assembly into magnetically anisotropic hierarchical structures.  

PubMed

The effect of the morphology of ferrite nanoparticles on their assembly in a magnetic field was studied. Thin BaFe12O19 nanoplatelets were compared with isotropic, spherical or octahedral, CoFe2O4 nanoparticles, all of which were synthesized hydrothermally. The nanoplatelets and nanoparticles assembled into a variety of hierarchical structures from stable suspensions during the "drop deposition" and drying in a magnetic field. The alignment of the nanoparticles in the magnetic field was observed in situ with an optical microscope. The morphologies of the nanoparticles and the subsequent assemblies were observed with transmission and scanning electron microscopes, respectively. The magnetic properties of the nanoparticles and the assemblies were measured with a vibrating-sample magnetometer. The BaFe12O19 nanoplatelets aligned in the plane of the substrate and formed several-micrometers-thick, ordered films with a magnetic alignment of approximately 90%. The CoFe2O4 nanoparticles assembled into thick, dense columns with a height of several hundreds of micrometers and showed a magnetic alignment of up to 60%. The differences in the morphologies and the magnetic alignments between the BaFe12O19 and CoFe2O4 hierarchical structures could be explained in terms of the differences in the shape and magnetocrystalline structure of the specific nanoparticles. PMID:24841592

Lisjak, Darja; Jenuš, Petra; Mertelj, Alenka

2014-06-10

206

Cancer Theranostics: The Rise of Targeted Magnetic Nanoparticles  

PubMed Central

Interest in utilizing magnetic nanoparticles (MNP) for biomedical applications has grown considerably over the past two decades. This excitement is driven in large part by the success of MNPs as contrast agents in magnetic resonance imaging (MRI). The recent investigative trend with respect to cancer has continued down a diagnostic path, but has also turned toward concurrent therapy – giving rise to the distinction of MNPs as potential “theranostics”. Here we review both the key technical principles of MNPs and the ongoing advancement toward a cancer theranostic MNP. Recent progress in diagnostics, hyperthermia treatments, and drug delivery are all considered. We conclude by identifying current barriers to clinical translation of MNPs and offer considerations for their future development. PMID:21489647

Cole, Adam J.; Yang, Victor C.; David, Allan E.

2011-01-01

207

Chemisorption of cyanogen chloride by spinel ferrite magnetic nanoparticles.  

PubMed

Spinel ferrite magnetic nanoparticles, MnFe2O4, NiFe2O4, and CoFe2O4, were synthesized and used as gas-phase adsorbents for the removal of cyanogen chloride from dry air. Fixed-bed adsorption breakthrough experiments show adsorption wave behavior at the leading edge of the breakthrough curve that is not typical of physically adsorbed species. Fourier transform infrared spectroscopy (FTIR) results indicate that CK is reacting with the spinel ferrite surface and forming a carbamate species. The reaction is shown to be a function of the hydroxyl groups and adsorbed water on the surface of the particles as well as the metallic composition of the particles. The surface reaction decreases the remnant and saturation magnetism of the MnFe2O4 and CoFe2O4 particles by approximately 25%. PMID:23540752

Glover, T Grant; DeCoste, Jared B; Sabo, Daniel; Zhang, Z John

2013-05-01

208

Multifunctional hybrid silica nanoparticles based on [Mo?Br??]²? phosphorescent nanosized clusters, magnetic ?-Fe?O? and plasmonic gold nanoparticles.  

PubMed

We report on the synthesis, characterization and photophysical study of new luminescent and magnetic hybrid silica nanoparticles. Our method is based on the co-encapsulation of single maghemite ?-Fe2O3 nanoparticles and luminescent molybdenum cluster units [Mo6Br(i)8Br(a)6](2-) through a water-in-oil (W/O) microemulsion technique. The as-prepared core-shell [Cs2Mo6Br14-?Fe2O3]@SiO2 nanoparticles (45-53 nm) possess a single magnetic core (6, 10.5 or 15 nm) and the cluster units are dispersed in the entire volume of the silica sphere. The [Cs2Mo6Br14-?Fe2O3]@SiO2 nanoparticles have a perfect spherical shape with a good monodispersity and they display red and near-infrared (NIR) emission in water under UV excitation, whose intensity depends on the magnetic core size. The hybrid nanoparticles have been characterized by transmission electron microscopy (TEM), high annular angular dark field scanning transmission electron microscopy (HAADF-STEM), energy-dispersive X-ray spectroscopy (EDX), UV-Vis-NIR spectroscopy and magnetometer SQUID analysis. Small gold nanoparticles were successfully nucleated at the surface of the hybrid silica nanoparticles in order to add plasmonic properties. PMID:24767509

Nerambourg, Nicolas; Aubert, Tangi; Neaime, Chrystelle; Cordier, Stéphane; Mortier, Michel; Patriarche, Gilles; Grasset, Fabien

2014-06-15

209

Superparamagnetic iron oxide nanoparticles: magnetic nanoplatforms as drug carriers  

PubMed Central

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 ?-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

Wahajuddin; Arora, Sumit

2012-01-01

210

Nano-particle magnetism with a dispersion of particle sizes  

NASA Astrophysics Data System (ADS)

In this paper, different definitions of the distribution functions that can be used to account for the magnetization of dispersed nano-particle systems are discussed. The volume and number weighted distributions are both found to be equally valid for the representation of distribution functions in nanoparticle magnetic systems. This study also shows that the room temperature magnetization curve M(H) of a superparamagnetic system is sensitive to the particle size distribution parameters and, that for a non-interacting system, these parameters can be unambiguously determined. Furthermore, the temperature variation of the initial susceptibility ?(T) for a dispersion of particle sizes is also examined using both the exact and the critical approaches. The critical approach is found to be a reasonable and valid approximation, since the discrepancy in the calculated ?(T) curves between the exact and the approximated form of the function exp(-tm/?) was found to be very small. For a dispersion of anisotropy energies, both approaches adequately describe the unblocking process of the particle magnetic moments within the system when the temperature is increased. In this study, the distribution of the critical transition temperatures that can be obtained from the temperature variation of the initial susceptibility is also examined. For different definitions of the distribution functions, the retrieved distributions from the experimental data are bound to be different. Furthermore, the calculated temperature variation of the initial susceptibility is found to be sensitive to the constant value of the frequency factor f0 used in the calculations. The discrepancy in calculating the ?(T) curve using an improper value of f0 is larger than that discrepancy arising from the step-like approximation of exp(-tm/?). Thus, the f0 value has to be calculated using the physical parameters of the system and not just taken as a constant value between 109 and 1011 Hz.

El-Hilo, M.

2012-11-01

211

Magnetoabsorption and magnetic hysteresis in Ni ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Nickel ferrite nanoparticles were prepared by a modified sol-gel technique employing coconut oil, and then annealed at different temperatures in 400-1200 °C range. This route of preparation has revealed to be one efficient and cheap technique to obtain high quality nickel ferrite nanosized powder. Sample particles sizes obtained with XRD data and Scherrer's formula lie in 13 nm to 138 nm, with increased size with annealing temperature. Hysteresis loops have been obtained at room temperature with an inductive method. Magnetic field induced microwave absorption in nanoscale ferrites is a recent an active area of research, in order to characterize and explore potential novel applications. In the present work microwave magnetoabsorption data of the annealed nickel ferrite nanoparticles are presented. These data have been obtained with a system based on a network analyzer that operates in the frequency range 0 - 8.5 GHz. At fields up to 400 mT we can observe a peak according to ferromagnetic resonance theory. Sample annealed at higher temperature exhibits different absorption, coercivity and saturation magnetization figures, revealing its multidomain character.

Hernández-Gómez, P.; Muñoz, J. M.; Valente, M. A.; Torres, C.; de Francisco, C.

2013-01-01

212

Second-harmonic generation in magnetic colloids by orientation of the nanoparticles  

Microsoft Academic Search

We show that an optical second harmonic (SH) is generated in a magnetic colloid if a static magnetic field which breaks the fluid isotropy is applied. We propose a statistical model in which all the magnetic nanoparticles are supposed to be identical with a nonzero complex second-order polarizability tensor bound to their magnetic moment. These grains align under a static

J. Lenglet; A. Bourdon; J.-C. Bacri; R. Perzynski; G. Demouchy

1996-01-01

213

Magnetic nanoparticles formed in glasses co-doped with iron and larger radius elements  

SciTech Connect

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 studies.

Edelman, I.; Ivanova, O.; Ivantsov, R.; Velikanov, D.; Zabluda, V. [L.V. Kirensky Institute of Physics SB RAS, 660036 Krasnoyarsk (Russian Federation); Zubavichus, Y.; Veligzhanin, A. [NRC 'Kurchatov Institute,' 123182 Moscow (Russian Federation); Zaikovskiy, V. [Boreskov Institute of Catalysis, Siberian Branch of RAS, 630090 Novosibirsk (Russian Federation); Stepanov, S. [S.I. Vavilov State Optical Institute, St. Petersburg (Russian Federation); Artemenko, A. [ICMCB, UPR CNRS 9048, 33608 Pessac cedex (France); Curely, J.; Kliava, J. [LOMA, UMR 5798 Universite Bordeaux 1-CNRS, 33405 Talence cedex (France)

2012-10-15

214

Effect of large mechanical stress on the magnetic properties of embedded Fe nanoparticles  

PubMed Central

Summary Magnetic nanoparticles are promising candidates for next generation high density magnetic data storage devices. Data storage requires precise control of the magnetic properties of materials, in which the magnetic anisotropy plays a dominant role. Since the total magneto-crystalline anisotropy energy scales with the particle volume, the storage density in media composed of individual nanoparticles is limited by the onset of superparamagnetism. One solution to overcome this limitation is the use of materials with extremely large magneto-crystalline anisotropy. In this article, we follow an alternative approach by using magneto-elastic interactions to tailor the total effective magnetic anisotropy of the nanoparticles. By applying large biaxial stress to nanoparticles embedded in a non-magnetic film, it is demonstrated that a significant modification of the magnetic properties can be achieved. The stress is applied to the nanoparticles through expansion of the substrate during hydrogen loading. Experimental evidence for stress induced magnetic effects is presented based on temperature-dependent magnetization curves of superparamagnetic Fe particles. The results show the potential of the approach for adjusting the magnetic properties of nanoparticles, which is essential for application in future data storage media. PMID:21977439

Saranu, Srinivasa; Selve, Soren; Kaiser, Ute; Han, Luyang; Wiedwald, Ulf; Ziemann, Paul

2011-01-01

215

Nano- and microstructures of magnetic field-guided maghemite nanoparticles in diblock copolymer films.  

PubMed

The control over the alignment of nanoparticles within a block copolymer matrix was investigated for different external magnetic fields with respect to producing well-aligned, highly oriented metal-oxide-polymer nanopatterns. Hybrid films were prepared by solution casting under a range of external magnetic fields. The nano- and microstructure of maghemite nanoparticles within poly(styrene-b-methyl methacrylate) diblock copolymer films as a function of the nanoparticle concentration was studied using optical microscopy, atomic force microscopy, scanning electron microscopy, and grazing incidence small-angle X-ray scattering. Because of a polystyrene (PS) coating, the nanoparticles are incorporated in the PS domains of the diblock copolymer morphology. At higher nanoparticle concentrations, nanoparticle aggregates perturb the block copolymer structure and accumulate at the films surface into wire-shaped stripes. These wire-shaped nanoparticle aggregates form mainly because of the competition between nanoparticle-polymer friction and magnetic dipolar interaction. The magnetic behavior of the hybrid films was probed at different temperatures for two orthogonal directions (with the line-shaped particle aggregates parallel and perpendicular to the magnetic field). The hybrid film systems show superparamagnetic behavior and remarkable shape anisotropy that render them interesting for magnetic applications. PMID:24621173

Yao, Yuan; Metwalli, Ezzeldin; Niedermeier, Martin A; Opel, Matthias; Lin, Chen; Ning, Jing; Perlich, Jan; Roth, Stephan V; Müller-Buschbaum, Peter

2014-04-01

216

The use of magnetic nanoparticles in thermal therapy monitoring and screening: Localization and imaging (invited)  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles have many diagnostic and therapeutic applications. A method termed magnetic spectroscopy of nanoparticle Brownian motion (MSB) was developed to interrogate in vivo the microscopic environment surrounding magnetic nanoparticles. We can monitor several effects that are important in thermal therapy and screening including temperature measurement and the bound state distribution. Here we report on simulations of nanoparticle localization. Measuring the spatial distribution of nanoparticles would allow us to identify ovarian cancer much earlier when it is still curable or monitor thermal therapies more accurately. We demonstrate that with well-designed equipment superior signal to noise ratio (SNR) can be achieved using only two harmonics rather than using all the harmonics containing signal. Alternatively, smaller magnetic field amplitudes can be used to achieve the same SNR. The SNR is improved using fewer harmonics because the noise is limited.

Weaver, John B.

2012-04-01

217

Fluorescent chitosan functionalized magnetic polymeric nanoparticles: Cytotoxicity and in vitro evaluation of cellular uptake.  

PubMed

Nanoparticles possessing magnetic and fluorescent properties were fabricated by the covalent attachment of fluorescein isothiocyanate onto magnetic polymeric nanoparticles functionalized by chitosan. The synthesized magnetic polymeric nanoparticles-chitosan/fluorescein isothiocyanate were successfully used for labeling the living organ and blood-related cancer cells, i.e., HeLa, Hep G2, and K562 cells. The cytotoxicity test of nanoparticles at various incubation times indicated the high cell viability (>90%) without morphological change. The confocal microscopy revealed that they could pass through cell membrane within 2?h for K562 cells and 3?h for HeLa and Hep G2 cells and then confine inside cytoplasm of all types of tested cells for at least 24?h. Therefore, the synthesized magnetic polymeric nanoparticles-chitosan/fluorescein isothiocyanate would potentially be used as cell tracking in theranostic applications. PMID:24951458

Kaewsaneha, Chariya; Jangpatarapongsa, Kulachart; Tangchaikeeree, Tienrat; Polpanich, Duangporn; Tangboriboonrat, Pramuan

2014-11-01

218

Magnetic Nanoparticle Characterization Using Nano-SQUID based on Niobium Dayem Bridges  

NASA Astrophysics Data System (ADS)

Magnetic nano-sensors based on niobium dc SQUID (Superconducting Quantum Interference Device) for nanoparticle characterization are presented. The SQUIDs consists of two Dayem bridges of 90 nm x 250 nm and loop area of 4, 1 and 0.55 ?m2. The SQUIDs were designed to have a hysteretic current-voltage characteristic in order to work as a magnetic flux-current transducer. Current-voltage characteristics, critical current as a function of the external magnetic field and switching current distributions were performed at liquid helium temperature. A critical current modulation of about 20% and a current-magnetic flux transfer coefficient (responsivity) of 30 ?A/?0 have been obtained, resulting in a magnetic flux resolution better than 1 m?0. In order to show the effectiveness of sensor for nanomagnetism applications, we performed measurements with and without magnetic nanoparticles on the SQUID loop applying a magnetic field parallel to the SQUID plane. In this configuration the magnetic flux coupled to the SQUID is mainly due to the presence of magnetic nanoparticles. The magnetic nanoparticles can be easily detected and their response to magnetic field studied. Measurements has been performed on Fe3O4 nanoparticles prepared by thermal decomposition method with a nominal particle size of 8 nm. Some examples of magnetization measurements were recorded at low temperature after Zero Field Cooling.

Russo, R.; Esposito, E.; Granata, C.; Vettoliere, A.; Russo, M.; Cannas, C.; Peddis, D.; Fiorani, D.

219

The effect of surface spin disorder on the magnetism of ?-Fe2O3 nanoparticle dispersions  

NASA Astrophysics Data System (ADS)

The nanomagnetism of monodisperse 7 nm ?-Fe2O3 nanoparticles exhibits unique features due to a significant amount of surface spin disorder. To correctly characterize the superparamagnetism of a dilute dispersion requires including the effects of the magnetic anisotropy and a shell of disordered spins surrounding the ordered core. The nanoparticle shell's disordered spin structure is exchange coupled to that of the ordered core. This enables an exchange bias loop shift, Hex, when the nanoparticle dispersion is field cooled. The surface spin disorder also leads to an unusual exponential-like decrease of the nanoparticle's total saturation magnetization with increasing temperature.

Shendruk, T. N.; Desautels, R. D.; Southern, B. W.; van Lierop, J.

2007-11-01

220

Nanoparticles as magnetic resonance imaging contrast agents for vascular and cardiac diseases  

PubMed Central

Advances in nanoparticle contrast agents for molecular imaging have made magnetic resonance imaging a promising modality for noninvasive visualization and assessment of vascular and cardiac disease processes. This review provides a description of the various nanoparticles exploited for imaging cardiovascular targets. Nanoparticle probes detecting inflammation, apoptosis, extracellular matrix, and angiogenesis may provide tools for assessing the risk of progressive vascular dysfunction and heart failure. The utility of nanoparticles as multimodal probes and/or theranostic agents has also been investigated. Although clinical application of these nanoparticles is largely unexplored, the potential for enhancing disease diagnosis and treatment is considerable. PMID:20967875

Chen, Wei; Cormode, David P.; Fayad, Zahi A.; Mulder, Willem J. M.

2011-01-01

221

Site determination and magnetism of Mn doping in protein encapsulated iron oxide nanoparticles  

Microsoft Academic Search

Soft x-ray absorption spectroscopy, soft x-ray magnetic circular dichroism, and alternating current magnetic susceptibility were performed on 6.7 nm iron oxide nanoparticles doped with (5%-33%) Mn grown inside the horse-spleen ferritin protein cages and compared to similarly protein encapsulated pure Fe-oxide and Mn-oxide nanoparticles to determine the site of the Mn dopant and to quantify the magnetic behavior with varying

V. Pool; M. Klem; C. Jolley; E. A. Arenholz; T. Douglas; M. Young; Y. U. Idzerda

2010-01-01

222

Release of magnetic nanoparticles from cell-encapsulating biodegradable nanobiomaterials.  

PubMed

The future of tissue engineering requires development of intelligent biomaterials using nanoparticles. Magnetic nanoparticles (MNPs) have several applications in biology and medicine; one example is Food and Drug Administration (FDA)-approved contrast agents in magnetic resonance imaging. Recently, MNPs have been encapsulated within cell-encapsulating hydrogels to create novel nanobiomaterials (i.e., M-gels), which can be manipulated and assembled in magnetic fields. The M-gels can be used as building blocks for bottom-up tissue engineering to create 3D tissue constructs. For tissue engineering applications of M-gels, it is essential to study the release of encapsulated MNPs from the hydrogel polymer network and the effect of MNPs on hydrogel properties, including mechanical characteristics, porosity, swelling behavior, and cellular response (e.g., viability, growth). Therefore, we evaluated the release of MNPs from photocrosslinkable gelatin methacrylate hydrogels as the polymer network undergoes biodegradation using inductively coupled plasma atomic emission spectroscopy. MNP release correlated linearly with hydrogel biodegradation rate with correlation factors (Pearson product moment correlation coefficient) of 0.96 ± 0.03 and 0.99 ± 0.01 for MNP concentrations of 1% and 5%, respectively. We also evaluated the effect of MNPs on hydrogel mechanical properties, porosity, and swelling behavior, as well as cell viability and growth in MNP-encapsulating hydrogels. Fibroblasts encapsulated with MNPs in hydrogels remained viable (>80% at t = 144 h) and formed microtissue constructs in culture (t = 144 h). These results indicated that MNP-encapsulating hydrogels show promise as intelligent nanobiomaterials, with great potential to impact broad areas of bioengineering, including tissue engineering, regenerative medicine, and pharmaceutical applications. PMID:22680777

Xu, Feng; Inci, Fatih; Mullick, Omer; Gurkan, Umut Atakan; Sung, Yuree; Kavaz, Doga; Li, Baoqiang; Denkbas, Emir Baki; Demirci, Utkan

2012-08-28

223

Release of Magnetic Nanoparticles from Cell-Encapsulating Biodegradable Nanobiomaterials  

PubMed Central

The future of tissue engineering requires development of intelligent biomaterials using nanoparticles. Magnetic nanoparticles (MNPs) have several applications in biology and medicine; one example is Food and Drug Administration (FDA)-approved contrast agents in magnetic resonance imaging. Recently, MNPs have been encapsulated within cell-encapsulating hydrogels to create novel nanobiomaterials (i.e., M-gels), which can be manipulated and assembled in magnetic fields. The M-gels can be used as building blocks for bottom-up tissue engineering to create 3D tissue constructs. For tissue engineering applications of M-gels, it is essential to study the release of encapsulated MNPs from the hydrogel polymer network and the effect of MNPs on hydrogel properties, including mechanical characteristics, porosity, swelling behavior, and cellular response (e.g., viability, growth). Therefore, we evaluated the release of MNPs from photocrosslinkable gelatin methacrylate hydrogels as the polymer network undergoes biodegradation using inductively coupled plasma atomic emission spectroscopy. MNP release correlated linearly with hydrogel biodegradation rate with correlation factors (Pearson product moment correlation coefficient) of 0.96 ± 0.03 and 0.99 ± 0.01 for MNP concentrations of 1% and 5%, respectively. We also evaluated the effect of MNPs on hydrogel mechanical properties, porosity, and swelling behavior, as well as cell viability and growth in MNP-encapsulating hydrogels. Fibroblasts encapsulated with MNPs in hydrogels remained viable (>80% at t = 144 h) and formed microtissue constructs in culture (t = 144 h). These results indicated that MNP-encapsulating hydrogels show promise as intelligent nanobiomaterials, with great potential to impact broad areas of bioengineering, including tissue engineering, regenerative medicine, and pharmaceutical applications. PMID:22680777

Xu, Feng; Inci, Fatih; Mullick, Omer; Gurkan, Umut Atakan; Sung, Yuree; Kavaz, Doga; Li, Baoqiang; Denkbas, Emir Baki; Demirci, Utkan

2013-01-01

224

Uptake and intracellular fate of fluorescent-magnetic glyco-nanoparticles.  

PubMed

Iron oxide based nanoparticles are finding their way as leading actors in nanotechnology applications to medicine. Magnetite nanoparticles are currently being used in clinics for the detection of hepatic tumors based on their unspecific accumulation in liver. More and more works are being published on potential applications of magnetic nanoparticles in diagnostics and therapy. But the interaction between magnetic nanoparticles and human cells at the subcellular level is only now beginning to be studied and more basic research is needed in this field. This work studies the interaction between carbohydrate functionalized gold-coated magnetite nanoparticles and C33 tumoural human cells as the first step towards the in vivo application of these nanoparticles. The uptake of this magnetic material follows a similar trend to that described for other nanoparticles. The intracellular fate of these nanoparticles once internalized has been unveiled, and an automatic methodology for the analysis of co-localization data has also been tested and compared to a more classic approach. These results can help in the optimization of the design of magnetic nanoparticles depending on their final application. PMID:23184744

Gallo, Juan; Genicio, Nuria; Penadés, Soledad

2012-05-01

225

Fatty Acid Binding Domain Mediated Conjugation of Ultrafine Magnetic Nanoparticles with Albumin Protein  

NASA Astrophysics Data System (ADS)

A novel bioconjugate of stearic acid capped maghemite nanoparticle (?-Fe2O3) with bovine serum albumin (BSA) was developed by taking recourse to the fatty acid binding property of the protein. From FT-IR study, it was found that conjugation took place covalently between the amine group of protein molecule and carboxyl group of stearic acid capped maghemite nanoparticle. TEM study further signified the morphology of the proposed nanobioconjuagte. The binding constant of nanoparticle with protein molecule was evaluated from the optical property studies. Also, magnetic measurement (M-H) showed retaining of magnetic property by significant values of saturation magnetization and other hysteretic parameters.

Bora, D. K.; Deb, P.

2009-02-01

226

Synthesis of cobalt nanoparticles in polymeric membrane and their magnetic anisotropy  

NASA Astrophysics Data System (ADS)

We systematically synthesized cobalt nanoparticles in the perfluorinated sulfo-cation membrane (MF-4SK) in aqua solution using ion-exchange method. The average radius of cobalt nanoparticles in the polymer film is determined to be 3.5±1.0 nm by TEM. FMR measurements show that the angle dependence of resonance field ( Hr) follows the characteristics of flat-plate magnetic film and the easy axis lies along the surface of the polymer film. The experimental results suggest that the magnetic anisotropy comes from magnetized polymer film containing Co nanoparticles.

Park, I.-W.; Yoon, M.; Kim, Y. M.; Kim, Y.; Kim, J. H.; Kim, S.; Volkov, V.

2004-05-01

227

In-Vitro Investigations of Nanoparticle Magnetic Thermotherapy: Adjuvant Effects and Comparison to Conventional Heating  

PubMed Central

Thermotherapy, particularly magnetic nanoparticle hyperthermia, is a promising modality both as a direct cancer cell killing and as a radiosensitization technique for adjuvant therapy. Dextran-coated iron oxide nanoparticles were mixed with multiple tumor cell lines in solution and exposed to varying magnetic field regimes and combined with traditional external radiotherapy. Heating of cell lines by water bath in temperature patterns comparable to those achieved by nanoparticle hyperthermia was conducted to assess the relative value of nano-magnetic thermotherapy compared with conventional bulk heating techniques and data.

Pierce, Z.; Strawbridge, R.; Gaito, C.; Dulatas, L.; Tate, J.; Ogden, J.; Hoopes, P.J.

2014-01-01

228

In Vivo and Real-Time Measurement of Magnetic Nanoparticles Distribution in Animals by Scanning SQUID Biosusceptometry for Biomedicine Study  

Microsoft Academic Search

Magnetic nanoparticles have been widely applied to biomagnetism, such as drug deliver, magnetic labeling, and con- trast agent for in vivo image, etc. To localize the distribution of these magnetic particles in living organism is the first important issue to confirm the effects of magnetic nanoparticles and also evaluate the possible untoward effects. In this study, a scanning high Tc

J. J. Chieh; W. K. Tseng; H. E. Horng; C. Y. Hong; H. C. Yang; C. C. Wu

2011-01-01

229

Magnetic and electronic structure of high-coercivity cobalt-carbide nanoparticles for permanent magnet applications  

NASA Astrophysics Data System (ADS)

Permanent magnets are important in numerous technological applications. However, those with the largest energy product (BHmax) contain rare earth elements, which increase costs and introduce volatility into the supply chain. Recently, rare-earth free Co2C and Co3C nanoparticles (NPs) with large magnetic coercivity and BHmax have been synthesized using a polyol process [1]. Optimal BHmaxis found in a mixture of the two phases. In this system, the nature of the magnetic interparticle interactions and the origins of intrinsic magnetic properties of the Co-carbide phases are not fully understood. We have investigated the origins of the magnetic properties of Co2C and Co3C NPs using x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements at the Co L-edge and C K-edge. From differences in the electronic structures of the two Co-carbide phases, as determined by XAS, the nature of their unique magnetic properties can be deduced. Furthermore, the role of the spin and orbital moments in determining magnetic anisotropy and BHmax in these materials is examined with XMCD. [1] V. G. Harris et al. J. Phys. D: Appl. Phys. 43, 165003 (2010).

Sterbinsky, George; Carroll, Kyler; Yoon, Hyojung; Meng, Shirley; Huba, Zachary; Carpenter, Everett; Arena, Dario

2013-03-01

230

Magnetic anisotropy considerations in magnetic force microscopy studies of single superparamagnetic nanoparticles.  

PubMed

In recent years, superparamagnetic nanoparticles (SPNs) have become increasingly important in applications ranging from solid state memory devices to biomedical diagnostic and therapeutic tools. However, detection and characterization of the small and unstable magnetic moment of an SPN at the single particle level remains a challenge. Further, depending on their physical shape, crystalline structure or orientation, SPNs may also possess magnetic anisotropy, which can govern the extent to which their magnetic moments can align with an externally applied magnetic field. Here, we demonstrate how we can exploit the magnetic anisotropy of SPNs to enable uniform, highly-sensitive detection of single SPNs using magnetic force microscopy (MFM) in ambient air. Superconducting quantum interference device magnetometry and analytical transmission electron microscopy techniques are utilized to characterize the collective magnetic behavior, morphology and composition of the SPNs. Our results show how the consideration of magnetic anisotropy can enhance the ability of MFM to detect single SPNs at ambient room temperature with high force sensitivity and spatial resolution. PMID:23149438

Nocera, Tanya M; Chen, Jun; Murray, Christopher B; Agarwal, Gunjan

2012-12-14

231

Magnetic tumor targeting of ?-glucosidase immobilized iron oxide nanoparticles  

NASA Astrophysics Data System (ADS)

Directed enzyme/prodrug therapy (DEPT) has promising application for cancer therapy. However, most current DEPT strategies face shortcomings such as the loss of enzyme activity during preparation, low delivery and transduction efficiency in vivo and difficultly of monitoring. In this study, a novel magnetic directed enzyme/prodrug therapy (MDEPT) was set up by conjugating ?-glucosidase (?-Glu) to aminated, starch-coated, iron oxide magnetic iron oxide nanoparticles (MNPs), abbreviated as ?-Glu-MNP, using glutaraldehyde as the crosslinker. This ?-Glu-MNP was then characterized in detail by size distribution, zeta potential, FTIR spectra, TEM, SQUID and magnetophoretic mobility analysis. Compared to free enzyme, the conjugated ?-Glu on MNPs retained 85.54% ± 6.9% relative activity and showed much better temperature stability. The animal study results showed that ?-Glu-MNP displays preferable pharmacokinetics characteristics in relation to MNPs. With an adscititious magnetic field on the surface of a tumor, a significant quantity of ?-Glu-MNP was selectively delivered into a subcutaneous tumor of a glioma-bearing mouse. Remarkably, the enzyme activity of the delivered ?-Glu in tumor lesions showed as high as 20.123±5.022 mU g-1 tissue with 2.14 of tumor/non-tumor ?-Glu activity.

Zhou, Jie; Zhang, Jian; David, Allan E.; Yang, Victor C.

2013-09-01

232

Magnetic tumor targeting of ?-Glucosidase immobilized iron oxide nanoparticles  

PubMed Central

Directed enzyme/prodrug therapy (DEPT) has promising application for cancer therapy. However, most current DEPT strategies face shortcomings such as the loss of enzyme activity during preparation, low delivery and transduction efficiency in vivo, difficult to be monitored. In current study, a novel magnetic directed enzyme/prodrug therapy (MDEPT) was set up by conjugating ?-Glucosidase (?-Glu) to aminated, starch-coated, iron oxide magnetic iron oxide nanoparticles (MNP), abbreviated as ?-Glu-MNP, using glutaraldehyde as the crosslinker. This ?-Glu-MNP was then characterized in detail by size distribution, zeta potential, FTIR spectra, TEM, SQUID and magnetophoretic mobility analysis. Compared to free enzyme, the conjugated ?-Glu on MNP remained 85.54%±6.9% relative activity and showed much better temperature stability. relative activity and showed much better temperature stability. The animal study results showed that ?-Glu-MNP display preferable pharmacokinetics characteristic in relation to MNP. With adscititious magnetic field on the surface of tumor, a significant quantity of ?-Glu-MNP was selectively delivered into a subcutaneous tumor of glioma-bearing mice. Remarkably, the enzyme activity of the delivered ?-Glu in tumor lesions showed as high as 20.123 ± 5.022 mU/g tissue with 2.14 of tumor/non-turmor of ?-Glu activity. PMID:23974977

Zhou, Jie; Zhang, Jian; David, Allan E.; Yang, Victor C.

2014-01-01

233

Nanoparticle Pharmacokinetic Profiling in vivo using Magnetic Resonance Imaging  

PubMed Central

Contrast agents targeted to molecular markers of disease are currently being developed with the goal of identifying disease early and evaluating treatment effectiveness using non-invasive imaging modalities such as MRI. Pharmacokinetic profiling of the binding of targeted contrast agents, while theoretically possible with MRI, has thus far only been demonstrated with more sensitive imaging techniques. Paramagnetic liquid perfluorocarbon nanoparticles were formulated to target ?v?3-integrins associated with early atherosclerosis in cholesterol-fed rabbits in order to produce a measurable signal increase on magnetic resonance images after binding. In this work, we combine quantitative information of the in vivo binding of this agent over time obtained via MRI with blood sampling to derive pharmacokinetic parameters using simultaneous and individual fitting of the data to a three compartment model. A doubling of tissue exposure (or area under the curve) is obtained with targeted as compared to control nanoparticles, and key parameter differences are discovered that may aid in development of models for targeted drug delivery. PMID:19025903

Neubauer, Anne M.; Sim, Hoon; Winter, Patrick M.; Caruthers, Shelton D.; Williams, Todd A.; Robertson, J. David; Sept, David; Lanza, Gregory M.; Wickline, Samuel A.

2008-01-01

234

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

NASA Astrophysics Data System (ADS)

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 (?-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.

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

2014-03-01

235

Synthesis and magnetic properties of DyMnO3 nanoparticles in mesoporous silica  

NASA Astrophysics Data System (ADS)

We synthesized nanoparticles of the perovskite manganite DyMnO3 in pores of mesoporous silica SBA-15 and investigated their magnetic properties. X-ray diffraction patterns of the nanoparticles indicated successful synthesis of the DyMnO3 nanoparticles with a particle size of about 10 nm in the pores of SBA-15. The temperature dependence of the DC magnetic susceptibility for the DyMnO3 nanoparticles exhibited a pronounced magnetic irreversibility between the field-cooling and the zero-field-cooling susceptibility due to the blocking phenomena and indicated a change of the magnetic exchange interactions from those for the bulk crystal. The in-phase susceptibility ?' and the out-of-phase susceptibility ?? of the AC susceptibility for the nanoparticles exhibited a peak at the blocking temperature, and that peak shifted toward higher temperature with increasing frequency. Magnetization curves for the nanoparticles were reproduced by using a Langevin function and exhibited a hysteresis loop at temperatures below the blocking temperature. Magnetic size effects and superparamagnetic behaviors were observed in the DyMnO3 nanoparticles.

Tajiri, Takayuki; Kohno, Atsushi; Hamamoto, Kenta; Ando, Yuhki; Deguchi, Hiroyuki; Mito, Masaki

2013-08-01

236

Silica-encapsulated magnetic nanoparticles: enzyme immobilization and cytotoxic study.  

PubMed

Silica-encapsulated magnetic nanoparticles (MNPs) were prepared via microemulsion method. The products were characterized by high resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray spectrum (EDS). MNPs with no observed cytotoxic activity against human lung carcinoma cell and brine shrimp lethality were used as suitable support for glucose oxidase (GOD) immobilization. Binding of GOD onto the support was confirmed by the FTIR spectra. The amount of immobilized GODs was 95 mg/g. Storage stability study showed that the immobilized GOD retained 98% of its initial activity after 45 days and 90% of the activity was also remained after 12 repeated uses. Considerable enhancements in thermal stabilities were observed for the immobilized GOD at elevated temperatures up to 80°C and the activity of immobilized enzyme was less sensitive to pH changes in solution. PMID:22269345

Ashtari, Khadijeh; Khajeh, Khosro; Fasihi, Javad; Ashtari, Parviz; Ramazani, Ali; Vali, Hojatollah

2012-05-01

237

Magnetic properties of Fe-doped NiO nanoparticles  

NASA Astrophysics Data System (ADS)

Ni1- x Fe x O ( x = 0, 0.05, 0.1) nanoparticles with several nanometers encapsulated with amorphous SiO2 were prepared by our novel preparation method. A NiO single phase structure was confirmed using the X-ray diffraction measurements. It is considered that Ni ions are replaced by Fe ions because it is observed that the lattice constant decreases. The temperature dependence behavior of the magnetization revealed that the blocking temperature, T B , shifted from 17 to 57 K as the amount of Fe ions increased, and that below T B , ferromagnetic behaviors were exhibited. The coercive force, H C , increased from 0.8 to 1.5 kOe as the amount of Fe ions increased.

Kurokawa, A.; Sakai, N.; Zhu, L.; Takeuchi, H.; Yano, S.; Yanoh, T.; Onuma, K.; Kondo, T.; Miike, K.; Miyasaka, T.; Ichiyanagi, Y.

2013-08-01

238

Magnetic nanoparticle effects on the red blood cells  

NASA Astrophysics Data System (ADS)

In vitro tests on magnetite colloidal nanoparticles effects upon animal red blood cells were carried out. Magnetite cores were stabilized with citric acid in the form of biocompatible magnetic fluid administrated in different dilutions in the whole blood samples. The hemolysis extent was found increased up to 2.75 in horse blood and respectively up to 2.81 in the dog blood. The electronic transitions assigned to the heme group were found shifted with about 500 cm-1 or, respectively, affected by supplementary vibronic structures. The Raman vibrations assigned to oxyhemoglobin were much diminished in intensity probably due to the bonding of OH group from citrate shell to the heme iron ion.

Creang?, D. E.; Culea, M.; N?dejde, C.; Oancea, S.; Curecheriu, L.; Racuciu, M.

2009-05-01

239

Formation of nitrogen-doped graphene nanoscrolls by adsorption of magnetic ?-Fe2O3 nanoparticles  

NASA Astrophysics Data System (ADS)

Graphene nanoscrolls are Archimedean-type spirals formed by rolling single-layer graphene sheets. Their unique structure makes them conceptually interesting and understanding their formation gives important information on the manipulation and characteristics of various carbon nanostructures. Here we report a 100% efficient process to transform nitrogen-doped reduced graphene oxide sheets into homogeneous nanoscrolls by decoration with magnetic ?-Fe2O3 nanoparticles. Through a large number of control experiments, magnetic characterization of the decorated nanoparticles, and ab initio calculations, we conclude that the rolling is initiated by the strong adsorption of maghemite nanoparticles at nitrogen defects in the graphene lattice and their mutual magnetic interaction. The nanoscroll formation is fully reversible and upon removal of the maghemite nanoparticles, the nanoscrolls return to open sheets. Besides supplying information on the rolling mechanism of graphene nanoscrolls, our results also provide important information on the stabilization of iron oxide nanoparticles.

Sharifi, Tiva; Gracia-Espino, Eduardo; Reza Barzegar, Hamid; Jia, Xueen; Nitze, Florian; Hu, Guangzhi; Nordblad, Per; Tai, Cheuk-Wai; Wågberg, Thomas

2013-08-01

240

Measurement of molecular binding using the Brownian motion of magnetic nanoparticle probes  

NASA Astrophysics Data System (ADS)

Molecular binding is important in many venues including antibody binding for diagnostic and therapeutic agents and pharmaceutical function. We demonstrate that a method of measuring nanoparticle Brownian motion, termed magnetic spectroscopy of nanoparticle Brownian motion (MSB), can be used to monitor molecular binding and the bound fraction. It is plausible that MSB can be used to measure binding in vivo because the same signal has been used to image nanoparticles in nanogram quantities in vivo.

Rauwerdink, Adam M.; Weaver, John B.

2010-01-01

241

Engineered magnetic hybrid nanoparticles with enhanced relaxivity for tumor imaging.  

PubMed

Clinically used contrast agents for magnetic resonance imaging (MRI) suffer by the lack of specificity; short circulation time; and insufficient relaxivity. Here, a one-step combinatorial approach is described for the synthesis of magnetic lipid-polymer (hybrid) nanoparticles (MHNPs) encapsulating 5 nm ultra-small super-paramagnetic iron oxide particles (USPIOs) and decorated with Gd(3+) ions. The MHNPs comprise a hydrophobic poly(lactic acid-co-glycolic acid) (PLGA) core, containing up to ~5% USPIOs (w/w), stabilized by lipid and polyethylene glycol (PEG). Gd(3+) ions are directly chelated to the external lipid monolayer. Three different nanoparticle configurations are presented including Gd(3+) chelates only (Gd-MHNPs); USPIOs only (Fe-MHNPs); and the combination thereof (MHNPs). All three MHNPs exhibit a hydrodynamic diameter of about 150 nm. The Gd-MHNPs present a longitudinal relaxivity (r1 = 12.95 ± 0.53 (mM s)(-1)) about four times larger than conventional Gd-based contrast agents (r1 = 3.4 (mM s)(-1)); MHNPs have a transversal relaxivity of r2 = 164.07 ± 7.0 (mM s)(-1), which is three to four times larger than most conventional systems (r2 ~ 50 (mM s)(-1)). In melanoma bearing mice, elemental analysis for Gd shows about 3% of the injected MHNPs accumulating in the tumor and 2% still circulating in the blood, at 24 h post-injection. In a clinical 3T MRI scanner, MHNPs provide significant contrast confirming the observed tumor deposition. This approach can also accommodate the co-loading of hydrophobic therapeutic compounds in the MHNP core, paving the way for theranostic systems. PMID:23871540

Aryal, Santosh; Key, Jaehong; Stigliano, Cinzia; Ananta, Jeyarama S; Zhong, Meng; Decuzzi, Paolo

2013-10-01

242

Laser printing of silicon nanoparticles with resonant optical electric and magnetic responses  

NASA Astrophysics Data System (ADS)

Silicon nanoparticles with sizes of a few hundred nanometres exhibit unique optical properties due to their strong electric and magnetic dipole responses in the visible range. Here we demonstrate a novel laser printing technique for the controlled fabrication and precise deposition of silicon nanoparticles. Using femtosecond laser pulses it is possible to vary the size of Si nanoparticles and their crystallographic phase. Si nanoparticles produced by femtosecond laser printing are initially in an amorphous phase (a-Si). They can be converted into the crystalline phase (c-Si) by irradiating them with a second femtosecond laser pulse. The resonance-scattering spectrum of c-Si nanoparticles, compared with that of a-Si nanoparticles, is blue shifted and its peak intensity is about three times higher. Resonant optical responses of dielectric nanoparticles are characterized by accumulation of electromagnetic energy in the excited modes, which can be used for the realization of nanoantennas, nanolasers and metamaterials.

Zywietz, Urs; Evlyukhin, Andrey B.; Reinhardt, Carsten; Chichkov, Boris N.

2014-03-01

243

Structural and Magnetic Characterization of Superparamagnetic Iron Platinum Nanoparticle Contrast Agents for Magnetic Resonance Imaging  

PubMed Central

We report the synthesis, from simple salts, and the physical characterization of superparamagnetic iron platinum nanoparticles (SIPPs) suitable for use as contrast agents in magnetic resonance imaging. The properties of these particles were determined by means of transmission electron microscopy (TEM), thermogravimetric analysis (TGA), inductively coupled plasma-optical emission spectroscopy (ICP-OES), superconducting quantum interference device (SQUID) magnetometry, and nuclear magnetic resonance (NMR) relaxivity at 4.7 Tesla. TEM showed that the diameters of the particles ranged from 9.3 nm to 10 nm, depending on the mole ratio of iron to platinum precursors, and on the concentration of Octadecylamine (ODA) used in their preparation. The iron to platinum stoichiometry determined by ICP-OES varied from 1.4:1 to 3.7:1 and was similarly dependant on the initial mole ratios of iron and platinum salts, as well as on the concentration of ODA in the reaction. SQUID magnetometry showed that the SIPPs were superparamagnetic and had magnetic moments that increased with increasing iron content from 62 to 72 A•m2/kg Fe. The measured relaxivities of the SIPPs at 4.7 Tesla were higher than commercially available superparamagnetic iron oxide nanoparticles (SPIONs), suggesting that these particles may be superior contrast agents in T2-weighted magnetic resonance imaging (MRI). PMID:22872817

Taylor, Robert M.; Huber, Dale L.; Monson, Todd C.; Esch, Victor; Sillerud, Laurel O.

2012-01-01

244

Structural and magnetic characterization of superparamagnetic iron platinum nanoparticle contrast agents for magnetic resonance imaging  

PubMed Central

The authors report the synthesis, from simple salts, and the physical characterization of superparamagnetic iron platinum nanoparticles (SIPPs) suitable for use as contrast agents in magnetic resonance imaging. The properties of these particles were determined by means of transmission electron microscopy (TEM), thermogravimetric analysis, inductively coupled plasma-optical emission spectroscopy (ICP-OES), superconducting quantum interference device (SQUID) magnetometry, and nuclear magnetic resonance relaxivity at 4.7 T. TEM showed that the diameters of the particles ranged from 9.3 to 10 nm, depending on the mole ratio of iron to platinum precursors, and on the concentration of octadecylamine (ODA) used in their preparation. The iron to platinum stoichiometry determined by ICP-OES varied from 1.4:1 to 3.7:1 and was similarly dependent on the initial mole ratios of iron and platinum salts, as well as on the concentration of ODA in the reaction. SQUID magnetometry showed that the SIPPs were superparamagnetic and had magnetic moments that increased with increasing iron content from 62 to 72 A·m2/kg Fe. The measured relaxivities of the SIPPs at 4.7 T were higher than commercially available superparamagnetic iron oxide nanoparticles, suggesting that these particles may be superior contrast agents in T2-weighted magnetic resonance imaging. PMID:25317380

Taylor, Robert M.; Huber, Dale L.; Monson, Todd C.; Esch, Victor; Sillerud, Laurel O.

2012-01-01

245

M13-templated magnetic nanoparticles for targeted in vivo imaging of prostate cancer  

NASA Astrophysics Data System (ADS)

Molecular imaging allows clinicians to visualize the progression of tumours and obtain relevant information for patient diagnosis and treatment. Owing to their intrinsic optical, electrical and magnetic properties, nanoparticles are promising contrast agents for imaging dynamic molecular and cellular processes such as protein-protein interactions, enzyme activity or gene expression. Until now, nanoparticles have been engineered with targeting ligands such as antibodies and peptides to improve tumour specificity and uptake. However, excessive loading of ligands can reduce the targeting capabilities of the ligand and reduce the ability of the nanoparticle to bind to a finite number of receptors on cells. Increasing the number of nanoparticles delivered to cells by each targeting molecule would lead to higher signal-to-noise ratios and would improve image contrast. Here, we show that M13 filamentous bacteriophage can be used as a scaffold to display targeting ligands and multiple nanoparticles for magnetic resonance imaging of cancer cells and tumours in mice. Monodisperse iron oxide magnetic nanoparticles assemble along the M13 coat, and its distal end is engineered to display a peptide that targets SPARC glycoprotein, which is overexpressed in various cancers. Compared with nanoparticles that are directly functionalized with targeting peptides, our approach improves contrast because each SPARC-targeting molecule delivers a large number of nanoparticles into the cells. Moreover, the targeting ligand and nanoparticles could be easily exchanged for others, making this platform attractive for in vivo high-throughput screening and molecular detection.

Ghosh, Debadyuti; Lee, Youjin; Thomas, Stephanie; Kohli, Aditya G.; Yun, Dong Soo; Belcher, Angela M.; Kelly, Kimberly A.

2012-10-01

246

Observations of oxidation mechanisms and kinetics in faceted FeCo magnetic nanoparticles  

E-print Network

Observations of oxidation mechanisms and kinetics in faceted FeCo magnetic nanoparticles N. J Fe50Co50 97V2Nb1 nanoparticles were synthesized in an induction plasma torch and oxidized of oxidation present at different temperatures. The initial oxide layer was nearly Co-free, beginning at 3 nm

McHenry, Michael E.

247

Magnetic separation of colloidal nanoparticle mixtures using a material specific peptide.  

PubMed

A material specific peptide bound to Fe2O3 facilitates the selective sequestration of Au from a colloidal mixture of Au and CdS nanoparticles; the Au-Fe2O3 precipitate can then be magnetically separated from the colloidal CdS, and the Au nanoparticles can be recovered upon release from the Fe2O3. PMID:23661051

Essinger-Hileman, Elizabeth R; Popczun, Eric J; Schaak, Raymond E

2013-06-18

248

Fluorescence and magnetic properties of hydrogels containing Fe3O4 nanoparticles  

NASA Astrophysics Data System (ADS)

In this study, Fe3O4 (magnetite) nanoparticles were synthesized by in situ in polyacrylamide (PAAm) gels. Structural and magnetic properties of magnetite nanoparticles were investigated by X-Ray diffractometry (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM) methods. Interaction of pyranine molecules with Fe3O4 nanoparticles was investigated by fluorescence spectroscopy measurements in which pyranine (POH) molecules were used as a flouroprobe. It was observed that magnetite nanoparticles have single domain structure with average grain size of 12 nm which was also supported by magnetization measurements. M-H hysteresis curves revealed the superparamagnetic nature of magnetite nanoparticles synthesized in PAAm gels. Fluorescence measurements depicted that there is an interaction between POH and magnetite nanoparticles which was deduced from the presence of two new peaks at 380 nm and 405 nm in emission spectrum. Besides, it was observed that POH molecules could not diffuse into the gel when it consists of magnetite nanoparticles which also make the gel more homogeneous. As swelling ratio increases from 1 to 13, magnetization of the gel does not change which reveals that magnetic nanoparticles do not diffuse out of the gel during water-intake. This feature makes the gel suitable for applications as waste water treatments.

Alvero?lu, E.; Sözeri, H.; Baykal, A.; Kurtan, U.; ?enel, M.

2013-04-01

249

Magnetic nanoparticles sensitize MCF-7 breast cancer cells to doxorubicin-induced apoptosis  

PubMed Central

Background Resistance of breast cancer cells to the available chemotherapeutics is a major obstacle to successful treatment. Recent studies have shown that magnetic nanoparticles might have significant application in different medical fields including cancer treatment. The goal of this study is to verify the ability of magnetic nanoparticles to sensitize cancer cells to the clinically available chemotherapy. Methods The role of iron oxide nanoparticles, static magnetic field, or a combination in the enhancement of the apoptotic potential of doxorubicin against the resistant breast cancer cells, MCF-7 was evaluated using the MTT assay and the propidium iodide method. Results In the present study, results revealed that pre-incubation of MCF-7 cells with iron oxide nanoparticles before the addition of doxorubicin did not enhance doxorubicin-induced growth inhibition. Pre-incubation of MCF-7 cells with iron oxide nanoparticles followed by a static magnetic field exposure significantly (P?magnetic field was dose-dependent where the highest cytotoxicity was seen at 1 tesla. Further experiments revealed that the anti-proliferative effect of this treatment procedure is due to induction of apoptotic cell death. Conclusions These results might point to the importance of combining magnetic nanoparticles with a static magnetic field in treatment of doxorubicin-refractory breast cancer cells. PMID:22533492

2012-01-01

250

A novel technique for in situ aggregation of Gluconobacter oxydans using bio-adhesive magnetic nanoparticles.  

PubMed

Here, we present a novel technique to immobilize magnetic particles onto whole Gluconobacter oxydans in situ via a synthetic adhesive biomimetic material inspired by the protein glues of marine mussels. Our approach involves simple coating of a cell adherent polydopamine film onto magnetic nanoparticles, followed by conjugation of the polydopamine-coated nanoparticles to G. oxydans which resulted in cell aggregation. After optimization, 21.3 mg (wet cell weight) G. oxydans per milligram of nanoparticle was aggregated and separated with a magnet. Importantly, the G. oxydan aggregates showed high specific activity and good reusability. The facile approach offers the potential advantages of low cost, easy cell separation, low diffusion resistance, and high efficiency. Furthermore, the approach is a convenient platform technique for magnetization of cells in situ by direct mixing of nanoparticles with a cell suspension. PMID:22729662

Ni, Kefeng; Lu, Huimin; Wang, Cunxun; Black, Kvar C L; Wei, Dongzhi; Ren, Yuhong; Messersmith, Phillip B

2012-12-01

251

Molecularly imprinted magnetic nanoparticles as tunable stationary phase located in microfluidic channel for enantioseparation.  

PubMed

A microfluidic device integrated with molecularly imprinted magnetic nanoparticles as stationary phase was designed for rapid enantioseparation by capillary electrochromatography. The nanoparticles were synthesized by the co-polymerization of methacrylic acid and ethylene glycol dimethacrylate on 3-(methacryloyloxy)propyltrimethoxysilane-functionalized magnetic nanoparticles (25-nm diameter) in the presence of template molecule, and characterized with infrared spectroscopy, thermal gravimetric analysis, and transmission electron microscope. The imprinted nanoparticles (200-nm diameter) could be localized as stationary phase in the microchannel of microfluidic device with the tunable packing length by the help of an external magnetic field. Using S-ofloxacin as the template molecule, the preparation of imprinted nanoparticles, the composition and pH of mobile phase, and the separation voltage were optimized to obtain baseline separation of ofloxacin enantiomers within 195s. The analytical performance could be conveniently improved by varying the packing length of nanoparticles zone, showing an advantage over the conventional packed capillary electrochromatography. The linear ranges for amperometric detection of the enantiomers using carbon fiber microdisk electrode at +1.0 V (vs. Ag/AgCl) were from 1.0 to 500 microM and 5.0 to 500 microM with the detection limits of 0.4 and 2.0 microM, respectively. The magnetically tunable microfluidic device could be expanded to localize more than one kind of template-imprinted magnetic nanoparticles for realizing simultaneous analysis of different kinds of chiral compounds. PMID:20727525

Qu, Ping; Lei, Jianping; Zhang, Lei; Ouyang, Ruizhuo; Ju, Huangxian

2010-09-24

252

Deposition feature of Ni nanoparticles on halloysite template and magnetic properties of the composite.  

PubMed

A novel cermet composite with Ni nanoparticles deposited on a hollow cylindrical halloysite template is fabricated by electroless plating. Ni nanoparticles have a uniform distribution on the template, and their average diameter is mainly in the range of 20-30 nm. The halloysite template will be beneficial to make the Ni nanoparticles achieve high stability and well-dispersed state. Different heat treatment temperatures have a great effect on the crystal structure of Ni nanoparticles and the magnetic properties of the composite. With the heat-treated temperature increase, Ni nanoparticles gradually become crystallized, and the composite values of inherent coercive force (iHc), saturated magnetization (Ms), and residual magnetization (Mr) increase respectively. After complete crystallization of Ni nanoparticles at 673 K, the composite has the maximum values of iHc (253.6 Oe), Ms (57.37 emu/g), and Mr (21.64 emu/g). The sum contribution of the magneto-crystalline anisotropy, single magnetic domain effect, and the pinning effect of multiple-twinned planar defects in Ni nanoparticles would result in the high value of iHc. The new nanosized cermet composite will be at such an advantage for its practicable fabrication method, higher coercive force, high stability, and low cost that it would have great potential to be utilized to design and prepare magnetic materials. PMID:16108436

Fu, Yubin; Zhang, Lide

2005-07-01

253

Polarized-neutron-diffraction study of the microscopic magnetic structure in ?''-Fe 16N2 nanoparticles  

NASA Astrophysics Data System (ADS)

Polarized-neutron-diffraction (PND) measurements were carried out using a pseudo-single-phase powder sample of ferromagnetic ?''-Fe16N2 nanoparticles. For the well-identified ?''-Fe16N2 phase, sizes of the magnetic moments at the three crystallographic Fe sites were determined in the absolute scale. The agreement between the magnetization value deduced from the present PND and that measured by a magnetometer (MVSM) supports the hypothesis that MVSM is primarily caused by the magnetization value in the target ?''-Fe16N2 ; thus there is no evidence for macroscopic giant saturation magnetization, at least for ?''-Fe16N2 nanoparticles. On the basis of the large magnetic moment size at one of the Fe sites, a possible coexisting state of localized spins and itinerant electron spins is inferred. Drawing a distinction between thin films and nanoparticles is currently necessary because of their divergent magnetic evolutions.

Hiraka, H.; Ohoyama, K.; Ogata, Y.; Ogawa, T.; Gallage, R.; Kobayashi, N.; Takahashi, M.; Gillon, B.; Gukasov, A.; Yamada, K.

2014-10-01

254

Application in the Ethanol Fermentation of Immobilized Yeast Cells in Matrix of Alginate/Magnetic Nanoparticles, on Chitosan-Magnetite Microparticles and Cellulose-coated Magnetic Nanoparticles  

E-print Network

Saccharomyces cerevisiae cells were entrapped in matrix of alginate and magnetic nanoparticles and covalently immobilized on magnetite-containing chitosan and cellulose-coated magnetic nanoparticles. Cellulose-coated magnetic nanoparticles with covalently immobilized thermostable {\\alpha}-amylase and chitosan particles with immobilized glucoamylase were also prepared. The immobilized cells and enzymes were applied in column reactors - 1/for simultaneous corn starch saccharification with the immobilized glucoamylase and production of ethanol with the entrapped or covalently immobilized yeast cells, 2/ for separate ethanol fermentation of the starch hydrolysates with the fixed yeasts. Hydrolysis of corn starch with the immobilized {\\alpha}-amylase and glucoamylase, and separate hydrolysis with the immobilized {\\alpha}-amylase were also examined. In the first reactor the ethanol yield reached approx. 91% of the theoretical; the yield was approx. 86% in the second. The ethanol fermentation was affected by the typ...

Ivanova, Viara; Hristov, Jordan

2011-01-01

255

Short-chain PEG molecules strongly bound to magnetic nanoparticle for MRI long circulating agents.  

PubMed

This study developed an approach for the synthesis of magnetic nanoparticles coated with three different polyethylene glycol (PEG)-derived molecules. The influence of the coating on different properties of the nanoparticles was studied. Magnetite nanoparticles (7 and 12 nm in diameter) were obtained via thermal decomposition of a coordination complex as an iron precursor to ensure nanoparticle homogeneity in size and shape. Particles were first coated with meso-2,3-dimercaptosuccinic acid by a ligand exchange process to remove oleic acid, followed by modification with three distinct short-chain PEG polymers, which were covalently bound to the nanoparticle surface via 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride activation of the carboxylic acids. In all cases, colloidal suspensions had hydrodynamic sizes <100 nm and low surface charge, demonstrating the effect of PEG coating on the aggregation properties and steric stabilization of the magnetic nanoparticles. The internalization and biocompatibility of these materials in the HeLa human cervical carcinoma cell line were tested. Cells preincubated with PEG-coated iron nanoparticles were visualized outside the cells, and their biocompatibility at high Fe concentrations was demonstrated using a standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Finally, relaxivity parameters (r1 and r2) were used to evaluate the efficiency of suspensions as magnetic resonance imaging contrast agents; the r2 value was similar to that for Resovist and up to four times higher than that for Sinerem, probably due to the larger nanoparticle size. The time of residence in blood of the nanoparticles measured from the relaxivity values, and the Fe content in blood was doubled for rats and rabbits due to the PEG on the nanoparticle surface. The results suggest that this PEGylation strategy for large magnetic nanoparticles (>10nm) holds promise for biomedical applications. PMID:23321305

Ruiz, A; Salas, G; Calero, M; Hernández, Y; Villanueva, A; Herranz, F; Veintemillas-Verdaguer, S; Martínez, E; Barber, D F; Morales, M P

2013-05-01

256

Microstructural and Pinning Properties of Thin Films Doped With Magnetic Nanoparticles  

Microsoft Academic Search

In this paper, we report a strong enhancement in the in-field transport properties of the YBa2Cu3O7-delta (YBCO) thin films doped with magnetic Fe2O3 nanoparticles. We incorporated magnetic Fe2O3 nanoparticles with two different architectures by laser ablation of the YBCO and dopant targets. YBCO film thickness was controlled at around 1 mum for all the samples. We conducted a detailed microstructural

Jie Wang; Chen-Fong Tsai; Zhenxing Bi; Donald G. Naugle; Haiyan Wang

2009-01-01

257

Preparation, magnetic characterization, and optical band gap of EuTiO 3 nanoparticles  

Microsoft Academic Search

Perovskite-type polycrystalline EuTiO3 (ETO) nanoparticles were synthesized using the simple sol–gel technique. We investigated the magnetic properties of the as-prepared ETO nanoparticles and revealed the G-AFM phase below the Néel temperature (TN). Furthermore, the transition from the G-AFM order to the FM order, induced by magnetic field, was also demonstrated. The optical band gap of 1.03eV for the as-prepared ETO

T. Wei; H. P. Liu; Y. F. Chen; H. Y. Yan; J.-M. Liu

2011-01-01

258

Labelling of cultured macrophages with novel magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic resonance (MR) imaging is capable of demonstrating human anatomy and pathological conditions. Iron oxide magnetic nanoparticles (MNPs) have been used in MR imaging as liver-specific contrast medium, cellular and molecular imaging probes. Because few studies focused on the MNPs other than iron oxides, we developed FeNi alloy MNPs coated with polyethylenimine (PEI). In this study, we demonstrated PEI-coated FeNi MNPs are able to label the cells, which could be detected in MR imaging. For labelling purpose, MNPs were incubated with mouse macrophage cell line (Raw 264.7) for 24 h and these PEI-labelled FeNi alloy MNPs can be uptaken by macrophages efficiently compared with Ferucarbotran, a commercialized superparamagnetic iron oxide (SPIO) under flow cytometry measurement. Besides, these cells labelled with MNPs could be imaged in MR with the identical potency as Ferucarbotran. Further investigation of the cells using Prussian blue staining revealed that FeNi alloy MNPs inside the cells is not oxidized. This phenomenon alleviated the consideration of potential risk of nickel toxicity. We conclude that PEI-coated FeNi MNPs could be candidate for MR contrast medium.

Hsiao, Jong-Kai; Tai, Ming-Fong; Lee, Yung-Chiang; Yang, Chung-Yi; Wang, Hsu-Yang; Liu, Hon-Man; Fang, Jau-Shiung; Chen, Shin-Tai

2006-09-01

259

Magnetic mesoporous silica nanoparticles: fabrication and their laccase immobilization performance.  

PubMed

Newly large-pore magnetic mesoporous silica nanoparticles (MMSNPs) with wormhole framework structures were synthesized for the first time by using tetraethyl orthosilicate as the silica source and amine-terminated Jeffamine surfactants as template. Iminodiacerate was attached on these MMSNPs through a silane-coupling agent and chelated with Cu(2+). The Cu(2+)-chelated MMSNPs (MMSNPs-CPTS-IDA-Cu(2+)) showed higher adsorption capacity of 98.1 mg g(-1)-particles and activity recovery of 92.5% for laccase via metal affinity adsorption in comparison with MMSNPs via physical adsorption. The Michaelis constant (K(m)) and catalytic constant (k(cat)) of laccase immobilized on the MMSNPs-CPTS-IDA-Cu(2+) were 3.28 mM and 155.4 min(-1), respectively. Storage stability and temperature endurance of the immobilized laccase on MMSNPs-CPTS-IDA-Cu(2+) increased significantly, and the immobilized laccase retained 86.6% of its initial activity after 10 successive batch reactions operated with magnetic separation. PMID:20655206

Wang, Feng; Guo, Chen; Yang, Liang-rong; Liu, Chun-Zhao

2010-12-01

260

Paclitaxel and iron oxide loaded multifunctional nanoparticles for chemotherapy, fluorescence properties, and magnetic resonance imaging.  

PubMed

The multifunctional nanoparticles constructed from triphenylamine-poly(lactide-co-glycolide)-poly(ethyleneglycol)-poly(lactide-co-glycolide) (TPA-PEP) and folate-poly(2-ethyl-2oxazoline)-poly(D,L-lactide) (folate-PEOz-PLA) were developed in this study. Iron oxide nanoparticles (IOP) and paclitaxel (PTX) were coencapsulated in the nanoparticles with diameter less than 200 nm. The drug-loaded nanoparticles emit fluorescence peak at 460 nm when excited with wavelength of 350 nm. The in vitro antitumor activity of the drug-loaded nanoparticles was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays against HeLa cells. When the cells were exposed to the nanoparticles with different levels of folate but the same drug loading, cell viability decreases as the level of folate increases. Confocal laser scanning microscopy (CLSM) analysis shows that cellular uptake is lower for the non-folate-nanoparticles than that for the folate-nanoparticles. The in vitro and in vivo magnetic resonance imaging (MRI) studies indicate the better T2-Weighted images can be obtained for the folate-nanoparticles. In the anticancer effect evaluation, tumor-bearing mice administered with the 30%-folate-nanoparticles showed ~50% reduction in tumor volume after 23 days. The multifunctional nanoparticles as drug carrier with capabilities of both tumor-targeting and MRI present a new direction in drug delivery system development. PMID:22374619

Chen, Yung-Chu; Lee, Wen-Fu; Tsai, Han-Hsueh; Hsieh, Wen-Yuan

2012-05-01

261

Effect of physical variables on capture of magnetic nanoparticles in simulated blood vessels  

NASA Astrophysics Data System (ADS)

This study investigated how the percent capture of magnetic nanoparticles in a simulated vessel varies with physical variables. Magnetic nanoparticles (MNPs) can used as part of therapeutic or diagnostic materials for cancer patients. By capturing these devices with a magnetic field, the particles can be concentrated in an area of diseased tissue. In this study, flow of nanoparticles in simulated blood vessels was used to determine the affect of applying an external magnetic field. This study used maghemite nanoparticles as the MNPs and either water or Fetal Bovine Serum as the carrier fluid. A UV-Vis collected capture data. The percent capture of MNPs was positively influenced by five physical variables: larger vessel diameters, lower linear flow velocity, higher magnetic field strength, better dispersion, lower MNP concentration, and lower protein content in fluid. Free MNPs were also compared to micelles, with the free particles having more successful magnetic capture. Four factors contributed to these trends: the strength of the magnetic field's influence on the MNPs, the MNPs' interactions with other particles and the fluid, the momentum of the nanoparticles, and magnetic mass to total mass ratio of the flowing particles.

Zhang, Minghui; Brazel, Christopher

2011-11-01

262

The influence of collective behavior on the magnetic and heating properties of iron oxide nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles with a high specific absorption rate (SAR) have been developed and used in mouse models of cancer. The magnetic nanoparticles are comprised of predominantly iron oxide magnetic cores surrounded by a dextran layer for colloidal stability. The average diameter of a single particle (core plus dextran) is 92±14nm as measured by photon correlation spectroscopy. Small angle neutron scattering measurements under several H2O/D2O contrast conditions and at varying nanoparticle concentrations have revealed three length scales: >10?m, several hundred nanometers, and tens of nanometers. The latter corresponds to the particle diameter; the several hundred nanometers corresponds to a hard sphere interaction radius of the core/shell nanoparticles; >10?m corresponds to the formation of long-range, many-particle structures held together by magnetic interactions and dextran. The long-range collective magnetic behavior appears to play a major role in enhancing the SAR. For samples having nominally equal concentrations and similar saturation magnetizations, the measured SAR is 1075W/(g of Fe) for tightly associated nanoparticles and 150W/(g of Fe) for very loosely associated nanoparticles at an applied field of 86kA/m (1080Oe) and 150kHz.

Dennis, C. L.; Jackson, A. J.; Borchers, J. A.; Ivkov, R.; Foreman, A. R.; Lau, J. W.; Goernitz, E.; Gruettner, C.

2008-04-01

263

Magnetic and structural properties of nanoparticles of nickel oxide  

NASA Astrophysics Data System (ADS)

In this dissertation, magnetic properties of NiO nanoparticles (NP) prepared by the sol-gel method in the size range D = 5 nm to 20 nm, with and without oleic acid (OA) coating, are reported. Transmission electron microscopy (TEM) studies show the morphology of the smaller particles to be primarily rod-like, changing over to nearly spherical shapes for D >10 nm. Average sizes D of NP determined by x-ray diffraction (XRD) are compared with the results from TEM. From the analysis of the XRD line intensities, the particle size dependence of the Debye-Waller factors for Ni and O atoms are derived. It is found that the Debye-Waller factors of nickel and oxygen atoms in smaller particles are larger than those in bulk NiO. For the coated and uncoated NiO nanorods of 5 nm diameter, variations of the magnetization M with temperature T (5 K to 370 K) and temperature variations of the EMR (electron magnetic resonance) spectra were measured to determine the respective blocking temperatures TB(m) and TB(EMR). The following differences are noted: (1) TB(m) is reduced from 230 K (uncoated) to 85 K(coated) for H = 25 Oe; (2) Decrease of TB(m) with H is weaker and the ratio TB(EMR)/T B(m) is smaller for the uncoated particles. These differences are due to stronger interparticle interaction present in the uncoated particles. Temperature variation (5 K-300 K) of the AC magnetic susceptibilities (chi' and chi") at various frequencies f (0.1-10,000 Hz) are reported for the coated and uncoated 5 nm diameter nanorods of NiO. Using the peak in chi' as the blocking temperature TB, it is observed that TB increases with increasing f. The data for the two samples fit the Vogel-Fulcher law: f = f0exp[-Ea/k(TB-T0)] with f 0 = 9.2 x 1011 Hz, Ea/k = 1085 K and T0 = 162 K (0 K) for the uncoated (coated) particles. This shows that T0 provides a good measure of the effects of interparticle interactions on magnetic relaxation and that these interactions are essentially eliminated with the OA coating. For all the particles, measurements of M versus T (5 K-370 K) in the zero-field cooled (ZFC) and field-cooled (FC) modes are used to determine the average blocking temperature TP. For the OA coated particles, TP increases with increase in size D as expected for superparamagnetic particles. However for the uncoated NP, TP decreases initially with increase in size for D < 10 nm; but for D > 10 nm, TP follows the same trend as for the coated NP. These differences are interpreted in terms of significant interparticle interaction. The data of M vs. the applied field H for T > TP are fit to the modified Langevin function: M = M0 L (muPH/kBT) + chiaH, to determine the magnetic moment muP per particle as a function of size D. The variation of muP with size D is interpreted in terms of the fraction of spins on the surface layer of the particles which contribute to mu P. It is observed that this fraction varies as 1/D reaching nearly 100 % for the 5 nm particles. From the temperature dependence of M0 and extrapolating to M0 ? 0, the Neel temperatures TN for various sizes are determined. TN for NiO nanoparticles is found to decreases rapidly with decrease in size for D < 10 nm.

Shim, Hyunja (Jenny)

264

Colloidal Stability and Monodispersible Magnetic Iron Oxide Nanoparticles in Biotechnology Application  

NASA Astrophysics Data System (ADS)

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.

Shamili, K.; Rajesh, E. M.; Rajendran, R.; Madhan Shankar, S. R.; Elango, M.; Abitha Devi, N.

2013-02-01

265

Assessment of Influence of Magnetic Forces on Aggregation of Zero-valent Iron Nanoparticles  

PubMed Central

Aggregation of zero-valent nanoparticles in groundwater is influenced by several physical phenomena. The article shortly introduces preceding works in modeling of aggregation of small particles including influence of sedimentation, velocity profile of water, heat fluctuations, and surface electric charge. A brief description of inclusion of magnetic forces into the model of aggregation follows. Rate of influence of the magnetic forces on the aggregation depends on the magnitude of magnetization of the particles, radius of nanoparticles, size of the aggregates, and their concentration in the solution. Presented results show that the magnetic forces have significant influence on aggregation especially of the smallest iron particles.

2011-01-01

266

Intracellular performance of tailored nanoparticle tracers in magnetic particle imaging  

NASA Astrophysics Data System (ADS)

Magnetic Particle Imaging (MPI) is a quantitative mass-sensitive, tracer-based imaging technique, with potential applications in various cellular imaging applications. The spatial resolution of MPI, in the first approximation, improves by decreasing the full width at half maximum (FWHM) of the field-derivative of the magnetization, dm/dH of the nanoparticle (NP) tracers. The FWHM of dm/dH depends critically on NPs' size, size distribution, and their environment. However, there is limited information on the MPI performance of the NPs after their internalization into cells. In this work, 30 to 150 ?g of the iron oxide NPs were incubated in a lysosome-like acidic buffer (0.2 ml, 20 mM citric acid, pH 4.7) and investigated by vibrating sample magnetometry, magnetic particle spectroscopy, transmission electron microscopy, and dynamic light scattering (DLS). The FWHM of the dm/dH curves of the NPs increased with incubation time and buffer to NPs ratio, consistent with a decrease in the median core size of the NPs from ˜20.1 ± 0.98 to ˜18.5 ± 3.15 nm. Further, these smaller degraded NPs formed aggregates that responded to the applied field by hysteretic reversal at higher field values and increased the FWHM. The rate of core size decrease and aggregation were inversely proportional to the concentration of the incubated NPs, due to their slower biodegradation kinetics. The results of this model experiment show that the MPI performance of the NPs in the acidic environments of the intracellular organelles (i.e., lysosomes and endosomes) can be highly dependent on their rate of internalization, residence time, and degradation.

Arami, Hamed; Krishnan, Kannan M.

2014-05-01

267

Tuning the surface magnetism of ?-Fe2O3 nanoparticles with a Cu shell  

NASA Astrophysics Data System (ADS)

An interfacial monolayer of CuO in Cu-coated ?-Fe2O3 nanoparticles enables significantly decreased intrinsic surface spin disorder compared to bare ?-Fe2O3 nanoparticles. Element specific x-ray absorption spectroscopy at the L-edges for Cu and Fe indicates that the magnetic moment of the CuO in the shell interacts with the ?-Fe2O3 nanoparticle's surface magnetic moments. This exchange interaction cants the moments of the CuO resulting in a non-zero Cu moment, altering the ?-Fe2O3 nanomagnetism.

Desautels, R. D.; Skoropata, E.; Chen, Y.-Y.; Ouyang, H.; Freeland, J. W.; van Lierop, J.

2011-12-01

268

The manipulation of natural killer cells to target tumor sites using magnetic nanoparticles.  

PubMed

The present work demonstrates that Cy5.5 conjugated Fe(3)O(4)/SiO(2) core/shell nanoparticles could allow us to control movement of human natural killer cells (NK-92MI) by an external magnetic field. Required concentration of the nanoparticles for the cell manipulation is as low as ~20 ?g Fe/mL. However, the relative ratio of the nanoparticles loaded NK-92MI cells infiltrated into the target tumor site is enhanced by 17-fold by applying magnetic field and their killing activity is still maintained as same as the NK-92MI cells without the nanoparticles. This approach allows us to open alternative clinical treatment with reduced toxicity of the nanoparticles and enhanced infiltration of immunology to the target site. PMID:22575830

Jang, Eue-Soon; Shin, June-Ho; Ren, Gang; Park, Mi-Jin; Cheng, Kai; Chen, Xiaoyuan; Wu, Joseph C; Sunwoo, John B; Cheng, Zhen

2012-08-01

269

Selective enrichment and sensitive detection of candidate disease biomarker using a novel surfactant-coated magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

In this study, novel surfactant-coated magnetic nanoparticles were synthesized and evaluated for enrichment performance towards the sensitive detection of disease biomarkers. Surfactants with phosphate ester groups (RD35A and RD66) were used as a coating to reduce aggregation and to enhance the nanoparticle dispersion. Importantly, sensitive enrichment of the target proteins using the antibody-functionalized magnetic nanoparticles (Ab@MNP) was obtained, with a five-fold increase in recovery compared to uncoated magnetic nanoparticles. Similarly, phosphopeptide enrichment using the NTA@MNP in standard samples showed that the nanoparticles could selectively enrich phosphorylated peptides.

Capangpangan, R. Y.; dela Rosa, M. A. C.; Chang, C. H.; Wang, W. C.; Peng, J.; Shih, S. J.; Chiang, M. H.; Tzou, D. L.; Lin, C. C.; Chen, Y. J.

2014-08-01

270

Magnetically Encoded Luminescent Composite Nanoparticles through Layer-by-Layer Self-Assembly.  

PubMed

Sensitive and rapid detection of multiple analytes and the collection of components from complex samples are important in fields ranging from bioassays/chemical assays, clinical diagnosis, to environmental monitoring. A convenient strategy for creating magnetically encoded luminescent CdTe@SiO2 @n?Fe3 O4 composite nanoparticles, by using a layer-by-layer self-assembly approach based on electrostatic interactions, is described. Silica-coated CdTe quantum dots (CdTe@SiO2 ) serve as core templates for the deposition of alternating layers of Fe3 O4 magnetic nanoparticles and poly(dimethyldiallyl ammonium chloride), to construct CdTe@SiO2 @n?Fe3 O4 (n=1, 2, 3, …?) composite nanoparticles with a defined number (n) of Fe3 O4 layers. Composite nanoparticles were characterized by zeta-potential analysis, fluorescence spectroscopy, vibrating sample magnetometry, and transmission electron microscopy, which showed that the CdTe@SiO2 @n?Fe3 O4 composite nanoparticles exhibited excellent luminescence properties coupled with well-defined magnetic responses. To demonstrate the utility of these magnetically encoded nanoparticles for near-simultaneous detection and separation of multiple components from complex samples, three different fluorescently labeled IgG proteins, as model targets, were identified and collected from a mixture by using the CdTe@SiO2 @n?Fe3 O4 nanoparticles. PMID:25258095

Song, Erqun; Han, Weiye; Xu, Hongyan; Jiang, Yunfei; Cheng, Dan; Song, Yang; Swihart, Mark T

2014-11-01

271

Direct synthesis of MOF-derived nanoporous carbon with magnetic Co nanoparticles toward efficient water treatment.  

PubMed

Nanoporous carbon particles with magnetic Co nanoparticles (Co/NPC particles) are synthesized by one-step carbonization of zeolitic imidazolate framework-67 (ZIF-67) crystals. After the carbonization, the original ZIF-67 shapes are preserved well. Fine magnetic Co nanoparticles are well dispersed in the nanoporous carbon matrix, with the result that the Co/NPC particles show a strong magnetic response. The obtained nanoporous carbons show a high surface area and well-developed graphitized wall, thereby realizing fast molecular diffusion of methylene blue (MB) molecules with excellent adsorption performance. The Co/NPC possesses an impressive saturation capacity for MB dye compared with the commercial activated carbon. Also, the dispersed magnetic Co nanoparticles facilitate easy magnetic separation. PMID:24610684

Torad, Nagy L; Hu, Ming; Ishihara, Shinsuke; Sukegawa, Hiroaki; Belik, Alexis A; Imura, Masataka; Ariga, Katsuhiko; Sakka, Yoshio; Yamauchi, Yusuke

2014-05-28

272

Distinguishing magnetic particle size of iron oxide nanoparticles with first-order reversal curves  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles encompass a wide range of scientific study and technological applications. The success of using the nanoparticles in various applications demands control over size, dispersibility, and magnetics. Hence, the nanoparticles are often characterized by transmission electron microscopy (TEM), X-ray diffraction, and magnetic hysteresis loops. TEM analysis requires a thin layer of dispersed particles on the grid, which may often lead to particle aggregation thus making size analysis difficult. Magnetic hysteresis loops on the other hand provide information on the bulk property of the material without discriminating size, composition, and interaction effects. First order reversal curves (FORCs), described as an assembly of partial hysteresis loops originating from the major loop are efficient in identifying the domain size, composition, and interaction in a magnetic system. This study presents FORC diagrams on a variety of well-characterized biogenic and synthetic magnetite nanoparticles. It also introduces deconvoluted reversible and irreversible components from FORC as an important method for obtaining a semi-quantitative measure of the effective magnetic particle size. This is particularly important in a system with aggregation and interaction among the particles that often leads to either the differences between physical size and effective magnetic size. We also emphasize the extraction of secondary components by masking dominant coercivity fraction on FORC diagram to explore more detailed characterization of nanoparticle systems.

Kumari, Monika; Widdrat, Marc; Tompa, Éva; Uebe, Rene; Schüler, Dirk; Pósfai, Mihály; Faivre, Damien; Hirt, Ann M.

2014-09-01

273

Robust antiferromagnetic coupling in hard-soft bi-magnetic core/shell nanoparticles  

NASA Astrophysics Data System (ADS)

The growing miniaturization demand of magnetic devices is fuelling the recent interest in bi-magnetic nanoparticles as ultimate small components. One of the main goals has been to reproduce practical magnetic properties observed so far in layered systems. In this context, although useful effects such as exchange bias or spring magnets have been demonstrated in core/shell nanoparticles, other interesting key properties for devices remain elusive. Here we show a robust antiferromagnetic (AFM) coupling in core/shell nanoparticles which, in turn, leads to the foremost elucidation of positive exchange bias in bi-magnetic hard-soft systems and the remarkable regulation of the resonance field and amplitude. The AFM coupling in iron oxide—manganese oxide based, soft/hard and hard/soft, core/shell nanoparticles is demonstrated by magnetometry, ferromagnetic resonance and X-ray magnetic circular dichroism. Monte Carlo simulations prove the consistency of the AFM coupling. This unique coupling could give rise to more advanced applications of bi-magnetic core/shell nanoparticles.

Estrader, M.; López-Ortega, A.; Estradé, S.; Golosovsky, I. V.; Salazar-Alvarez, G.; Vasilakaki, M.; Trohidou, K. N.; Varela, M.; Stanley, D. C.; Sinko, M.; Pechan, M. J.; Keavney, D. J.; Peiró, F.; Suriñach, S.; Baró, M. D.; Nogués, J.

2013-12-01

274

Magnetic resonance of the NiFe2O4 nanoparticles in the gigahertz range  

NASA Astrophysics Data System (ADS)

We report an adjustable magnetic resonance frequency from 1.45 to 2.54 GHz for NiFe2O4 nanoparticles which were prepared by a sol-gel process. X-ray diffraction and scanning electron microscopy results indicate that the samples are polycrystalline nanoparticles, and the size of the particles increases obviously with the thermal treatment temperature. The consequence of the surface composition suggests that the oxygen defects are present in the nanoparticle surface, and this surface magnetic state can show a strong surface anisotropy. With decreasing size of the particle, the surface magnetic effect is predominant, resulting in an increase of resonance frequency for NiFe2O4 nanoparticles. This finding provides a new route for NiFe2O4 materials that can be used in the gigahertz range.

Shi, Zhenhua; Zhang, Jing; Gao, Daqiang; Zhu, Zhonghua; Yang, Zhaolong; Zhang, Zhipeng; Xue, Desheng

2013-10-01

275

Synthesis and characterization of nickel ferrite magnetic nanoparticles by co-precipitation method  

NASA Astrophysics Data System (ADS)

Magnetic nickel ferrite (NiFe2O4) nanoparticles have been synthesized via co-precipitation method by varying the metal precursors ratio. Four different precursors ratio (Fe:Ni) are varied at 40:60, 50:50, 60:40 and 80:20. The size of the nanoparticles is found to increase with increasing iron (Fe) content. In addition, the morphology of the particles are observed to change from spherical to a shape similar to a nanooctahedral particle when the Fe content in the initial precursors ratio increases. The X-ray Diffraction (XRD) patterns have proved the presence of nickel ferrite nanoparticles. The magnetic properties characterized by Vibrating Sample Magnetometer (VSM) at room temperature proved that the assynthesized nickel ferrite nanoparticles are ferromagnetic and the saturation magnetization (Ms) increases with the content of Fe in the sample.

Ong, B. H.; Chee, E. S. C.; Abd Hamid, S. B. O. A.; Lim, K. P.

2012-11-01

276

Magnetic resonance of the NiFe2O4 nanoparticles in the gigahertz range.  

PubMed

We report an adjustable magnetic resonance frequency from 1.45 to 2.54 GHz for NiFe2O4 nanoparticles which were prepared by a sol-gel process. X-ray diffraction and scanning electron microscopy results indicate that the samples are polycrystalline nanoparticles, and the size of the particles increases obviously with the thermal treatment temperature. The consequence of the surface composition suggests that the oxygen defects are present in the nanoparticle surface, and this surface magnetic state can show a strong surface anisotropy. With decreasing size of the particle, the surface magnetic effect is predominant, resulting in an increase of resonance frequency for NiFe2O4 nanoparticles. This finding provides a new route for NiFe2O4 materials that can be used in the gigahertz range. PMID:24083340

Shi, Zhenhua; Zhang, Jing; Gao, Daqiang; Zhu, Zhonghua; Yang, Zhaolong; Zhang, Zhipeng; Xue, Desheng

2013-01-01

277

Structure and magnetic properties of Cr nanoparticles and Cr 2O 3 nanoparticles  

Microsoft Academic Search

We have synthesized Cr nanoparticles by arc-discharge and Cr2O3 nanoparticles by subsequent annealing the as-prepared Cr nanoparticles. The structure of these nanoparticles is studied by means of X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscope. Most of the particles show a good crystal habit of well-defined cubic or orthorhombic shape, while some small particles show spherical shape. The

W. S. Zhang; E. Brück; Z. D. Zhang; O. Tegus; W. F. Li; P. Z. Si; D. Y. Geng; K. H. J. Buschow

2005-01-01

278

Simulating physiological conditions to evaluate nanoparticles for magnetic fluid hyperthermia (MFH) therapy applications  

NASA Astrophysics Data System (ADS)

Magnetite nanoparticles with high self-heating capacity and low toxicity characteristics are a promising candidate for cancer hyperthermia treatment. In order to achieve minimum dosage to a patient, magnetic nanoparticles with high heating capacity are needed. In addition, the influence of physiological factors on the heat capacity of a material should be investigated in order to determine the feasibility. In this study, magnetite nanoparticles coated with lauric acid were prepared by co-precipitation of Fe 3+:Fe 2+ in a ratio of 2:1, 5:3, 3:2, and 4:3, and the pH was controlled using NaOH. Structural and magnetization characterization by means of X-ray diffractometry (XRD) and a superconducting quantum interference device (SQUID) revealed that the main species was Fe 3O 4 and further showed that most of the nanoparticles exhibited superparamagnetic properties. All of the magnetic nanoparticles showed a specific absorption rate (SAR) increase that was linear with the magnetic field strength and frequency of the alternating magnetic field. Among all, the magnetic nanoparticles prepared in a 3:2 ratio showed the highest SAR. To further test the influence of physiological factors on the 3:2 ratio magnetic nanoparticles, we simulated the environment with protein (bovine serum albumin, BSA), blood sugar (dextrose), electrolytes (commercial norm-saline) and viscosity (glycerol) to examine the heating capacity under these conditions. Our results showed that the SAR value was unaffected by the protein and blood sugar environments. On the other hand, the SAR value was significantly reduced in the electrolyte environment, due to precipitation and aggregation with sodium ions. For the simulated viscous environment with glycerol, the result showed that the SAR values reduced with increasing glycerol concentration. We have further tested the heating capacity contribution from the Néel mechanism by trapping the magnetic nanoparticles in a solid form of polydimethylsiloxane (PDMS) to eliminate the heating pathway due to a Brownian motion. We measured the heating capability and determined that 47% of the total heat generated by the magnetic nanoparticles was from the Néel mechanism contribution. For evaluating magnetic nanoparticles, this method provides a fast and low cost method for determining qualitative and quantitative information measurement for the effect of physiological interference and could greatly reduce the cost and time by in vitro or animal test.

Chen, Shihwei; Chiang, Chen-li; Hsieh, Shuchen

2010-01-01

279

Cancer therapy with drug loaded magnetic nanoparticles—magnetic drug targeting  

NASA Astrophysics Data System (ADS)

The aim of magnetic drug targeting (MDT) in cancer therapy is to concentrate chemotherapeutics to a tumor region while simultaneously the overall dose is reduced. This can be achieved with coated superparamagnetic nanoparticles bound to a chemotherapeutic agent. These particles are applied intra arterially close to the tumor region and focused to the tumor by a strong external magnetic field. The interaction of the particles with the field gradient leads to an accumulation in the region of interest (i.e. tumor). The particle enrichment and thereby the drug-load in the tumor during MDT has been proven by several analytical and imaging methods. Moreover, in pilot studies we investigated in an experimental in vivo tumor model the effectiveness of this approach. Complete tumor regressions without any negative side effects could be observed.

Alexiou, Christoph; Tietze, Rainer; Schreiber, Eveline; Jurgons, Roland; Richter, Heike; Trahms, Lutz; Rahn, Helene; Odenbach, Stefan; Lyer, Stefan

2011-05-01

280

Detection of c-reactive protein based on a magnetic immunoassay by using functional magnetic and fluorescent nanoparticles in microplates.  

PubMed

We report the preparation and application of biofunctional nanoparticles to detect C-reactive protein (CRP) in magnetic microplates. A CRP model biomarker was used to test the proposed detection method. Biofunctional magnetic nanoparticles, CRP, and biofunctional fluorescent nanoparticles were used in a sandwich nanoparticle immunoassay. The CRP concentrations in the samples were deduced from the reference plot, using the fluorescence intensity of the sandwich nanoparticle immunoassay. When biofunctional nanoparticles were used to detect CRP, the detection limit was 1.0 ng ml(-1) and the linear range was between 1.18 ng ml(-1) and 11.8 ?g ml(-1). The results revealed that the method involving biofunctional nanoparticles exhibited a lower detection limit and a wider linear range than those of the enzyme-linked immunosorbent assay (ELISA) and most other methods. For CRP measurements of serum samples, the differences between this method and ELISA in CRP measurements of serum samples were less than 13%. The proposed method can reduce the analysis time to one-third that of ELISA. This method demonstrates the potential to replace ELISA for rapidly detecting biomarkers with a low detection limit and a wide dynamic range. PMID:25142023

Yang, S F; Gao, B Z; Tsai, H Y; Fuh, C Bor

2014-11-01

281

Spontaneous synthesis of gold nanoparticles on gum arabic-modified iron oxide nanoparticles as a magnetically recoverable nanocatalyst  

NASA Astrophysics Data System (ADS)

A novel magnetically recoverable Au nanocatalyst was fabricated by spontaneous green synthesis of Au nanoparticles on the surface of gum arabic-modified Fe3O4 nanoparticles. A layer of Au nanoparticles with thickness of about 2 nm was deposited on the surface of gum arabic-modified Fe3O4 nanoparticles, because gum arabic acted as a reducing agent and a stabilizing agent simultaneously. The resultant magnetically recoverable Au nanocatalyst exhibited good catalytic activity for the reduction of 4-nitrophenol with sodium borohydride. The rate constants evaluated in terms of pseudo-first-order kinetic model increased with increase in the amount of Au nanocatalyst or decrease in the initial concentration of 4-nitrophenol. The kinetic data suggested that this catalytic reaction was diffusion-controlled, owing to the presence of gum arabic layer. In addition, this nanocatalyst exhibited good stability. Its activity had no significant decrease after five recycles. This work is useful for the development and application of magnetically recoverable Au nanocatalyst on the basis of green chemistry principles.

Wu, Chien-Chen; Chen, Dong-Hwang

2012-06-01

282

Spontaneous synthesis of gold nanoparticles on gum arabic-modified iron oxide nanoparticles as a magnetically recoverable nanocatalyst  

PubMed Central

A novel magnetically recoverable Au nanocatalyst was fabricated by spontaneous green synthesis of Au nanoparticles on the surface of gum arabic-modified Fe3O4 nanoparticles. A layer of Au nanoparticles with thickness of about 2?nm was deposited on the surface of gum arabic-modified Fe3O4 nanoparticles, because gum arabic acted as a reducing agent and a stabilizing agent simultaneously. The resultant magnetically recoverable Au nanocatalyst exhibited good catalytic activity for the reduction of 4-nitrophenol with sodium borohydride. The rate constants evaluated in terms of pseudo-first-order kinetic model increased with increase in the amount of Au nanocatalyst or decrease in the initial concentration of 4-nitrophenol. The kinetic data suggested that this catalytic reaction was diffusion-controlled, owing to the presence of gum arabic layer. In addition, this nanocatalyst exhibited good stability. Its activity had no significant decrease after five recycles. This work is useful for the development and application of magnetically recoverable Au nanocatalyst on the basis of green chemistry principles. PMID:22713480

2012-01-01

283

Spontaneous synthesis of gold nanoparticles on gum arabic-modified iron oxide nanoparticles as a magnetically recoverable nanocatalyst.  

PubMed

A novel magnetically recoverable Au nanocatalyst was fabricated by spontaneous green synthesis of Au nanoparticles on the surface of gum arabic-modified Fe3O4 nanoparticles. A layer of Au nanoparticles with thickness of about 2?nm was deposited on the surface of gum arabic-modified Fe3O4 nanoparticles, because gum arabic acted as a reducing agent and a stabilizing agent simultaneously. The resultant magnetically recoverable Au nanocatalyst exhibited good catalytic activity for the reduction of 4-nitrophenol with sodium borohydride. The rate constants evaluated in terms of pseudo-first-order kinetic model increased with increase in the amount of Au nanocatalyst or decrease in the initial concentration of 4-nitrophenol. The kinetic data suggested that this catalytic reaction was diffusion-controlled, owing to the presence of gum arabic layer. In addition, this nanocatalyst exhibited good stability. Its activity had no significant decrease after five recycles. This work is useful for the development and application of magnetically recoverable Au nanocatalyst on the basis of green chemistry principles. PMID:22713480

Wu, Chien-Chen; Chen, Dong-Hwang

2012-01-01

284

Magnetic nanoparticles for power absorption: Optimizing size, shape and magnetic properties  

SciTech Connect

We present a study on the magnetic properties of naked and silica-coated Fe{sub 3}O{sub 4} nanoparticles with sizes between 5 and 110 nm. Their efficiency as heating agents was assessed through specific power absorption (SPA) measurements as a function of particle size and shape. The results show a strong dependence of the SPA with the particle size, with a maximum around 30 nm, as expected for a Neel relaxation mechanism in single-domain particles. The SiO{sub 2} shell thickness was found to play an important role in the SPA mechanism by hindering the heat outflow, thus decreasing the heating efficiency. It is concluded that a compromise between good heating efficiency and surface functionality for biomedical purposes can be attained by making the SiO{sub 2} functional coating as thin as possible. - Graphical Abstract: The magnetic properties of Fe{sub 3}O{sub 4} nanoparticles from 5 to 110 nm are presented, and their efficiency as heating agents discussed as a function of particle size, shape and surface functionalization.

Gonzalez-Fernandez, M.A. [Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid (Spain); Torres, T.E. [Instituto de Nanociencia de Aragon, Universidad de Zaragoza, Zaragoza (Spain); Departamento de Fisica de la Materia Condensada, Universidad de Zaragoza (Spain); Andres-Verges, M. [Departamento de Quimica Organica e Inorganica, Universidad de Extremadura, Badajoz (Spain); Costo, R. [Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid (Spain); Presa, P. de la [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, Las Rozas, Madrid (Spain); Serna, C.J.; Morales, M.P. [Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid (Spain); Marquina, C. [Departamento de Fisica de la Materia Condensada, Universidad de Zaragoza (Spain); Instituto de Ciencia de Materiales de Aragon, CSIC- Universidad de Zaragoza (Spain); Ibarra, M.R. [Instituto de Nanociencia de Aragon, Universidad de Zaragoza, Zaragoza (Spain); Departamento de Fisica de la Materia Condensada, Universidad de Zaragoza (Spain); Goya, G.F., E-mail: goya@unizar.e [Instituto de Nanociencia de Aragon, Universidad de Zaragoza, Zaragoza (Spain); Departamento de Fisica de la Materia Condensada, Universidad de Zaragoza (Spain)

2009-10-15

285

``Green'' functionalization of magnetic nanoparticles via tea polyphenol for magnetic resonance/fluorescent dual-imaging  

NASA Astrophysics Data System (ADS)

Tea polyphenol serves as an environmentally friendly ligand-exchange molecule to synthesize multifunctional metal-doped superparamagnetic iron oxide nanoparticles via a catechol-metal coordination interaction. The resultant particles not only exhibit excellent hydrophilicity and protein adsorption resistance, but also are applicable as magnetic resonance/fluorescent dual-imaging probes due to their high T2 relaxivity, autofluorescence and large cellular uptake.Tea polyphenol serves as an environmentally friendly ligand-exchange molecule to synthesize multifunctional metal-doped superparamagnetic iron oxide nanoparticles via a catechol-metal coordination interaction. The resultant particles not only exhibit excellent hydrophilicity and protein adsorption resistance, but also are applicable as magnetic resonance/fluorescent dual-imaging probes due to their high T2 relaxivity, autofluorescence and large cellular uptake. Electronic supplementary information (ESI) available: Additional information and figures (Fig. S1-S7), including experimental sections, characterization of the products, protein corona analysis, cytotoxicity and cellular uptake quantification. See DOI: 10.1039/c3nr05003c

Jiang, Wen; Lai, Kuilin; Liu, Kexia; Xia, Rui; Gao, Fabao; Wu, Yao; Gu, Zhongwei

2014-01-01

286

Morphological effect of oscillating magnetic nanoparticles in killing tumor cells  

NASA Astrophysics Data System (ADS)

Forced oscillation of spherical and rod-shaped iron oxide magnetic nanoparticles (MNPs) via low-power and low-frequency alternating magnetic field (AMF) was firstly used to kill cancer cells in vitro. After being loaded by human cervical cancer cells line (HeLa) and then exposed to a 35-kHz AMF, MNPs mechanically damaged cell membranes and cytoplasm, decreasing the cell viability. It was found that the concentration and morphology of the MNPs significantly influenced the cell-killing efficiency of oscillating MNPs. In this preliminary study, when HeLa cells were pre-incubated with 100 ?g/mL rod-shaped MNPs (rMNP, length of 200 ± 50 nm and diameter of 50 to 120 nm) for 20 h, MTT assay proved that the cell viability decreased by 30.9% after being exposed to AMF for 2 h, while the cell viability decreased by 11.7% if spherical MNPs (sMNP, diameter of 200 ± 50 nm) were used for investigation. Furthermore, the morphological effect of MNPs on cell viability was confirmed by trypan blue assay: 39.5% rMNP-loaded cells and 15.1% sMNP-loaded cells were stained after being exposed to AMF for 2 h. It was also interesting to find that killing tumor cells at either higher (500 ?g/mL) or lower (20 ?g/mL) concentration of MNPs was less efficient than that achieved at 100 ?g/mL concentration. In conclusion, the relatively asymmetric morphological rod-shaped MNPs can kill cancer cells more effectively than spherical MNPs when being exposed to AMF by virtue of their mechanical oscillations.

Cheng, Dengfeng; Li, Xiao; Zhang, Guoxin; Shi, Hongcheng

2014-04-01

287

Morphological effect of oscillating magnetic nanoparticles in killing tumor cells  

PubMed Central

Forced oscillation of spherical and rod-shaped iron oxide magnetic nanoparticles (MNPs) via low-power and low-frequency alternating magnetic field (AMF) was firstly used to kill cancer cells in vitro. After being loaded by human cervical cancer cells line (HeLa) and then exposed to a 35-kHz AMF, MNPs mechanically damaged cell membranes and cytoplasm, decreasing the cell viability. It was found that the concentration and morphology of the MNPs significantly influenced the cell-killing efficiency of oscillating MNPs. In this preliminary study, when HeLa cells were pre-incubated with 100 ?g/mL rod-shaped MNPs (rMNP, length of 200?±?50 nm and diameter of 50 to 120 nm) for 20 h, MTT assay proved that the cell viability decreased by 30.9% after being exposed to AMF for 2 h, while the cell viability decreased by 11.7% if spherical MNPs (sMNP, diameter of 200?±?50 nm) were used for investigation. Furthermore, the morphological effect of MNPs on cell viability was confirmed by trypan blue assay: 39.5% rMNP-loaded cells and 15.1% sMNP-loaded cells were stained after being exposed to AMF for 2 h. It was also interesting to find that killing tumor cells at either higher (500 ?g/mL) or lower (20 ?g/mL) concentration of MNPs was less efficient than that achieved at 100 ?g/mL concentration. In conclusion, the relatively asymmetric morphological rod-shaped MNPs can kill cancer cells more effectively than spherical MNPs when being exposed to AMF by virtue of their mechanical oscillations. PMID:24872797

2014-01-01

288

Morphological effect of oscillating magnetic nanoparticles in killing tumor cells.  

PubMed

Forced oscillation of spherical and rod-shaped iron oxide magnetic nanoparticles (MNPs) via low-power and low-frequency alternating magnetic field (AMF) was firstly used to kill cancer cells in vitro. After being loaded by human cervical cancer cells line (HeLa) and then exposed to a 35-kHz AMF, MNPs mechanically damaged cell membranes and cytoplasm, decreasing the cell viability. It was found that the concentration and morphology of the MNPs significantly influenced the cell-killing efficiency of oscillating MNPs. In this preliminary study, when HeLa cells were pre-incubated with 100 ?g/mL rod-shaped MNPs (rMNP, length of 200?±?50 nm and diameter of 50 to 120 nm) for 20 h, MTT assay proved that the cell viability decreased by 30.9% after being exposed to AMF for 2 h, while the cell viability decreased by 11.7% if spherical MNPs (sMNP, diameter of 200?±?50 nm) were used for investigation. Furthermore, the morphological effect of MNPs on cell viability was confirmed by trypan blue assay: 39.5% rMNP-loaded cells and 15.1% sMNP-loaded cells were stained after being exposed to AMF for 2 h. It was also interesting to find that killing tumor cells at either higher (500 ?g/mL) or lower (20 ?g/mL) concentration of MNPs was less efficient than that achieved at 100 ?g/mL concentration. In conclusion, the relatively asymmetric morphological rod-shaped MNPs can kill cancer cells more effectively than spherical MNPs when being exposed to AMF by virtue of their mechanical oscillations. PMID:24872797

Cheng, Dengfeng; Li, Xiao; Zhang, Guoxin; Shi, Hongcheng

2014-01-01

289

Antiviral Properties of Silver Nanoparticles on a Magnetic Hybrid Colloid  

PubMed Central

Silver nanoparticles (AgNPs) are considered to be a potentially useful tool for controlling various pathogens. However, there are concerns about the release of AgNPs into environmental media, as they may generate adverse human health and ecological effects. In this study, we developed and evaluated a novel micrometer-sized magnetic hybrid colloid (MHC) decorated with variously sized AgNPs (AgNP-MHCs). After being applied for disinfection, these particles can be easily recovered from environmental media using their magnetic properties and remain effective for inactivating viral pathogens. We evaluated the efficacy of AgNP-MHCs for inactivating bacteriophage ?X174, murine norovirus (MNV), and adenovirus serotype 2 (AdV2). These target viruses were exposed to AgNP-MHCs for 1, 3, and 6 h at 25°C and then analyzed by plaque assay and real-time TaqMan PCR. The AgNP-MHCs were exposed to a wide range of pH levels and to tap and surface water to assess their antiviral effects under different environmental conditions. Among the three types of AgNP-MHCs tested, Ag30-MHCs displayed the highest efficacy for inactivating the viruses. The ?X174 and MNV were reduced by more than 2 log10 after exposure to 4.6 × 109 Ag30-MHCs/ml for 1 h. These results indicated that the AgNP-MHCs could be used to inactivate viral pathogens with minimum chance of potential release into environment. PMID:24487537

Park, SungJun; Park, Hye Hun; Kim, Sung Yeon; Kim, Su Jung; Woo, Kyoungja

2014-01-01

290

Antiviral properties of silver nanoparticles on a magnetic hybrid colloid.  

PubMed

Silver nanoparticles (AgNPs) are considered to be a potentially useful tool for controlling various pathogens. However, there are concerns about the release of AgNPs into environmental media, as they may generate adverse human health and ecological effects. In this study, we developed and evaluated a novel micrometer-sized magnetic hybrid colloid (MHC) decorated with variously sized AgNPs (AgNP-MHCs). After being applied for disinfection, these particles can be easily recovered from environmental media using their magnetic properties and remain effective for inactivating viral pathogens. We evaluated the efficacy of AgNP-MHCs for inactivating bacteriophage ?X174, murine norovirus (MNV), and adenovirus serotype 2 (AdV2). These target viruses were exposed to AgNP-MHCs for 1, 3, and 6 h at 25°C and then analyzed by plaque assay and real-time TaqMan PCR. The AgNP-MHCs were exposed to a wide range of pH levels and to tap and surface water to assess their antiviral effects under different environmental conditions. Among the three types of AgNP-MHCs tested, Ag30-MHCs displayed the highest efficacy for inactivating the viruses. The ?X174 and MNV were reduced by more than 2 log10 after exposure to 4.6 × 10(9) Ag30-MHCs/ml for 1 h. These results indicated that the AgNP-MHCs could be used to inactivate viral pathogens with minimum chance of potential release into environment. PMID:24487537

Park, SungJun; Park, Hye Hun; Kim, Sung Yeon; Kim, Su Jung; Woo, Kyoungja; Ko, GwangPyo

2014-04-01

291

Enrichment of malaria parasites by antibody immobilized magnetic nanoparticles.  

PubMed

The simple and less expensive technique based on magnetic nanoparticles (MNPs) was developed for separation of malaria parasites containing specific antigens. The carboxylated MNPs were chemically bound with anti-P. falciparum IgG antibodies (Ab-MNPs) purified from the plasma of malaria patients and then used for removal of P. falciparum malaria-infected erythrocytes from other non-infected blood cells in malaria culture at a given percent parasitemia. The results from optical microscope showed that all blood stages parasites, i.e., ring, trophozoite and schizont, could be separated from other blood components with high purity (> or = 95%) and yield of 33.5% (the early stages of ring and trophozoite:the schizont stage were 1:1.34). Highly specific interaction between Ab-MNPs and the P. falciparum malaria infected erythrocytes was confirmed by scanning electron microscope. When compared to the centrifugation with Percoll gradient and depletion by sorbitol lysis which are specific to the mature and the ring stages, respectively, our technique would be more useful for production of high quality of parasites to use in malaria pathogenesis or immunological studies, and in detection techniques. PMID:24015506

Tangchaikeeree, Tienrat; Jangpatarapongsa, Kulachart; Polpanich, Duangporn; Thiramanas, Raweewan; Pornjarone, Atcharavalai; Udnaen, Somkiat; Udomsangpetch, Rachanee; Tangboriboonrat, Pramuan

2013-10-01

292

Polymer-assisted iron oxide magnetic nanoparticle immobilized keratinase  

NASA Astrophysics Data System (ADS)

Nanotechnology holds the prospect for avant-garde changes to improve the performance of materials in various sectors. The domain of enzyme biotechnology is no exception. Immobilization of industrially important enzymes onto nanomaterials, with improved performance, would pave the way to myriad application-based commercialization. Keratinase produced by Bacillus subtilis was immobilized onto poly(ethylene glycol)-supported Fe3O4 superparamagnetic nanoparticles. The optimization process showed that the highest enzyme activity was noted when immobilized onto cyanamide-activated PEG-assisted MNP prepared under conditions of 25 °C and pH 7.2 of the reaction mixture before addition of H2O2 (3% w/w), 2% (w/v) PEG6000 and 0.062:1 molar ratio of PEG to FeCl2·4H2O. Further statistical optimization using response surface methodology yielded an R2 value that could explain more than 94% of the sample variations. Along with the magnetization studies, the immobilization of the enzyme onto the PEG-assisted MNP was characterized by UV, XRD, FTIR and TEM. The immobilization process had resulted in an almost fourfold increase in the enzyme activity over the free enzyme. Furthermore, the immobilized enzyme exhibited a significant thermostability, storage stability and recyclability. The leather-industry-oriented application of the immobilized enzyme was tested for the dehairing of goat-skin.

Konwarh, Rocktotpal; Karak, Niranjan; Rai, Sudhir Kumar; Mukherjee, Ashis Kumar

2009-06-01

293

Targeting of peptide conjugated magnetic nanoparticles to urokinase plasminogen activator receptor (uPAR) expressing cells  

NASA Astrophysics Data System (ADS)

Ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles are currently being used as a magnetic resonance imaging (MRI) contrast agent in vivo, mainly by their passive accumulation in tissues of interest. However, a higher specificity can ideally be achieved when the nanoparticles are targeted towards cell specific receptors and this may also facilitate specific drug delivery by an enhanced target-mediated endocytosis. We report efficient peptide-mediated targeting of magnetic nanoparticles to cells expressing the urokinase plasminogen activator receptor (uPAR), a surface biomarker for poor patient prognosis shared by several cancers including breast, colorectal, and gastric cancers. Conjugation of a uPAR specific targeting peptide onto polyethylene glycol (PEG) coated USPIO nanoparticles by click chemistry resulted in a five times higher uptake in vitro in a uPAR positive cell line compared to nanoparticles carrying a non-binding control peptide. In accordance with specific receptor-mediated recognition, a low uptake was observed in the presence of an excess of ATF, a natural ligand for uPAR. The uPAR specific magnetic nanoparticles can potentially provide a useful supplement for tumor patient management when combined with MRI and drug delivery.Ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles are currently being used as a magnetic resonance imaging (MRI) contrast agent in vivo, mainly by their passive accumulation in tissues of interest. However, a higher specificity can ideally be achieved when the nanoparticles are targeted towards cell specific receptors and this may also facilitate specific drug delivery by an enhanced target-mediated endocytosis. We report efficient peptide-mediated targeting of magnetic nanoparticles to cells expressing the urokinase plasminogen activator receptor (uPAR), a surface biomarker for poor patient prognosis shared by several cancers including breast, colorectal, and gastric cancers. Conjugation of a uPAR specific targeting peptide onto polyethylene glycol (PEG) coated USPIO nanoparticles by click chemistry resulted in a five times higher uptake in vitro in a uPAR positive cell line compared to nanoparticles carrying a non-binding control peptide. In accordance with specific receptor-mediated recognition, a low uptake was observed in the presence of an excess of ATF, a natural ligand for uPAR. The uPAR specific magnetic nanoparticles can potentially provide a useful supplement for tumor patient management when combined with MRI and drug delivery. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr32922d

Hansen, Line; Unmack Larsen, Esben Kjær; Nielsen, Erik Holm; Iversen, Frank; Liu, Zhuo; Thomsen, Karen; Pedersen, Michael; Skrydstrup, Troels; Nielsen, Niels Chr.; Ploug, Michael; Kjems, Jørgen

2013-08-01

294

Polymer- and dendrimer-coated magnetic nanoparticles as versatile supports for catalysts, scavengers, and reagents.  

PubMed

The work-up of chemical reactions by standard techniques is often time consuming and energy demanding, especially when chemists have to guarantee low levels of metal contamination in the products. Therefore, scientists need new ideas to rapidly purify reaction mixtures that are both economically and environmentally benign. One intriguing approach is to tether functionalities that are required to perform organic reactions to magnetic nanoparticles, for example, catalysts, reagents, scavengers, or chelators. This strategy allows researchers to quickly separate active agents from reaction mixtures by exploiting the magnetic properties of the support. In this Account, we discuss the main attributes of magnetic supports and describe how we can make the different nanomagnets accessible by surface functionalization. Arguably the most prominent magnetic nanoparticles are superparamagnetic iron oxide nanoparticles (SPIONs) due to their biologically well-accepted constituents, their established size-selective synthesis methods, and their diminished agglomeration (no residual magnetic attraction in the absence of an external magnetic field). However, nanoparticles made of pure metal have a considerably higher magnetization level that is useful in applications where high loadings are needed. A few layers of carbon can efficiently shield such highly reactive metal nanoparticles and, equally important, enable facile covalent functionalization via diazonium chemistry or non-covalent functionalization through ?-? interactions. We highlight carbon-coated cobalt (Co/C) and iron (Fe/C) nanoparticles in this Account and compare them to SPIONs stabilized with surfactants or silica shells. The graphene-like coating of these nanoparticles offers only low loadings with functional groups via direct surface modification, and the resulting nanomagnets are prone to agglomeration without effective steric stabilization. To overcome these restrictions and to tune the dispersibility of the magnetic supports in different solvents, we can introduce dendrimers and polymers on Co/C and Fe/C platforms by various synthetic strategies. While dendrimers have the advantage of being able to array all functional groups on the surface, polymers need fewer synthetic steps and higher molecular weight analogues are easily accessible. We present the application of these promising hybrid materials for the extraction of analytes or contaminates from complex aqueous solutions (e.g. waste water treatments or blood analytics), for metal-, organo-, and biocatalysis, and in organic synthesis. In addition, we describe advanced concepts like magnetic protecting groups, a multistep synthesis solely applying magnetic reagents and scavengers, and thermoresponsive self-separating magnetic catalysts. We also discuss the first examples of the use of magnetic scaffolds manipulated by external magnetic fields in flow reactors on the laboratory scale. These hold promise for future applications of magnetic hybrid materials in continuous flow or highly parallelized syntheses with rapid magnetic separation of the applied resins. PMID:24397296

Kainz, Quirin M; Reiser, Oliver

2014-02-18

295

Synthesis and surface engineering of magnetic nanoparticles for environmental cleanup and pesticide residue analysis: a review.  

PubMed

In recent years, water pollution and pesticide accumulation in the food chain have become a serious environmental and health hazard problem. Direct determination of these contaminants is a difficult task due to their low concentration level and the matrix interferences. Therefore, an efficient separation and preconcentration procedure is often required prior to the analysis. With the advancement in nanotechnology, various types of magnetic core-shell nanoparticles have successfully been synthesized and received considerable attention as sorbents for decontamination of diverse matrices. Magnetic core-shell nanoparticles with surface modifications have the advantages of large surface-area-to-volume ratio, high number of surface active sites, no secondary pollutant, and high magnetic properties. Due to their physicochemical properties, surface-modified magnetic core-shell nanoparticles exhibit high adsorption efficiency, high rate of removal of contaminants, and easy as well as rapid separation of adsorbent from solution via external magnetic field. Such facile separation is essential to improve the operation efficiency. In addition, reuse of nanoparticles would substantially reduce the treatment cost. In this review article, we have attempted to summarize recent studies that address the preconcentration methods of pesticide residue analysis and removal of toxic contaminants from aquatic systems using magnetic core-shell nanoparticles as adsorbents. PMID:24777942

Kaur, Ranjeet; Hasan, Abshar; Iqbal, Nusrat; Alam, Samsul; Saini, Mahesh Kr; Raza, Syed Kalbe

2014-07-01

296

Green synthetic, multifunctional hybrid micelles with shell embedded magnetic nanoparticles for theranostic applications.  

PubMed

The objective of this study is to design and develop a green-synthetic, multifunctional hybrid micelles with shell embedded magnetic nanoparticles for theranostic applications. The hybrid micelles were engineered based on complex micelles self-assembled from amphiphilic block copolymers Pluronic F127 and peptide-amphiphile (PA) pal-AAAAHHHD. The reason to choose PA is due to its amphiphilic character and the coordination capability for Fe(3+) and Fe(2+). The PA incorporation allows the in situ growth of the magnetic iron oxide nanoparticles onto the complex micelles, to yield the nanostructures with shell embedded magnetic nanoparticles at an ambient condition without any organic solvents. The anticancer drug doxorubicin (DOX) can be efficiently loaded into the hybrid micelles. Interestingly, the magnetic nanoparticles anchored on the shell were found to significantly retard the DOX release behavior of the drug loaded hybrid micelles. It was proposed that a cross-linking effect of the shell by magnetic nanoparticles is a key to underlie the above intriguing phenomenon, which could enhance the stability and control the drug diffusion of the hybrid micelles. Importantly, in vitro and in vivo magnetic resonance imaging (MRI) revealed the potential of these hybrid micelles to be served as a T2-weighted MR imaging contrast enhancer for clinical diagnosis. PMID:23815498

Li, Yongyong; Ma, Junping; Zhu, Haiyan; Gao, Xiaolong; Dong, Haiqing; Shi, Donglu

2013-08-14

297

Mechanisms of enhanced osteoblast gene expression in the presence of hydroxyapatite coated iron oxide magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

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 ?g ml-1, and from 12.5 to 200 ?g 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.

Tran, Nhiem; Hall, Douglas; Webster, Thomas J.

2012-11-01

298

Fabrication of 3D Tissue-Like Structure Ussing Magnetite Nanoparticles and Magnetic Force  

Microsoft Academic Search

Novel technologies to establish 3D tissue-like constructs are desired for tissue engineering. In the present study, magnetic force and magnetite nanoparticles were used to construct a layered mesenchymal stem cell (MSC) sheet, a layered cardiomyocyte sheet, and a layered fibroblast sheet involving capillaries. Magnetite cationic liposomes (MCLs) were taken up by the target cells. When a magnet was set under

A. Ito; K. Ino; K. Shimizu; H. Honda; M. Kamihira

2006-01-01

299

Clinical hyperthermia of prostate cancer using magnetic nanoparticles: Presentation of a new interstitial technique  

Microsoft Academic Search

The aim of this pilot study was to evaluate whether the technique of magnetic fluid hyperthermia can be used for minimally invasive treatment of prostate cancer. This paper presents the first clinical appli- cation of interstitial hyperthermia using magnetic nanoparticles in locally recurrent prostate cancer. Treatment planning was carried out using computerized tomography (CT) of the prostate. Based on the

M. Johannsen; U. Gneveckow; L. Eckelt; A. Feussner; N. WaldÖFner; R. Scholz; S. Deger; P. Wust; S. A. Loening; A. Jordan

2005-01-01

300

Detection of circulating tumor cells using targeted surface-enhanced Raman scattering nanoparticles and magnetic enrichment  

NASA Astrophysics Data System (ADS)

While more than 90% of cancer deaths are due to metastases, our ability to detect circulating tumor cells (CTCs) is limited by low numbers of these cells in the blood and factors confounding specificity of detection. We propose a magnetic enrichment and detection technique for detecting CTCs with high specificity. We targeted both magnetic and surface-enhanced Raman scattering (SERS) nanoparticles to cancer cells. Only cells that are dual-labeled with both kinds of nanoparticles demonstrate an increasing SERS signal over time due to magnetic trapping.

Shi, Wei; Paproski, Robert J.; Moore, Ronald; Zemp, Roger

2014-05-01

301

Enhancement of Quantum Efficiency of Organic Light Emitting Devices by Doping Magnetic Nanoparticles  

SciTech Connect

Magnetic nanoparticles of CoFe are used as dopants to enhance the quantum efficiency of electroluminance in a single layer organic light emitting device (OLED). The enhancement of quantum efficiency increases with both increasing density of CoFe nanoparticles and external magnetic field. For a given OLED with 0.1 wt % doping, the enhancement of the quantum efficiency reaches {approx}27% and {approx}32% without and with a magnetic field, respectively. The origin of these improvements could be attributed to the simultaneous increases of the portion of excitons among total charge carriers and the fraction of singlets among the total excitons

Sun, Chengjun [ORNL; Wu, Yue [ORNL; Xu, Zhihua [ORNL; Hu, Bin [University of Tennessee, Knoxville (UTK); Bai, Jianmin [University of Minnesota; Wang, Jian-Ping [University of Minnesota; Shen, Jian [ORNL

2007-01-01

302

Bacteria capture, lysate clearance, and plasmid DNA extraction using pH-sensitive multifunctional magnetic nanoparticles.  

PubMed

A multifunctional magnetic nanoparticle (MNP)-assisted bioseparation method was developed to isolate plasmid DNA (pDNA) from Escherichia coli culture. Using the pH-sensitive carboxyl-modified magnetic nanoparticles, both cell capture and the subsequent removal of genomic DNA/protein complex after lysis can be achieved simply by magnetic separation. Furthermore, the yield and purity of pDNA extracted by MNPs are comparable to those obtained using organic solvents or commercial kits. This time- and cost-effective protocol does not require centrifugation or precipitation steps and has the potential for automated DNA extraction, especially within miniaturized lab chip applications. PMID:19903448

Shan, Zhi; Wu, Qi; Wang, Xianxiang; Zhou, Zhongwu; Oakes, Ken D; Zhang, Xu; Huang, Qianming; Yang, Wanshen

2010-03-01

303

Magnetic nanoparticle-based therapeutic agents for thermo-chemotherapy treatment of cancer.  

PubMed

Magnetic nanoparticles have been widely investigated for their great potential as mediators of heat for localised hyperthermia therapy. Nanocarriers have also attracted increasing attention due to the possibility of delivering drugs at specific locations, therefore limiting systematic effects. The enhancement of the anti-cancer effect of chemotherapy with application of concurrent hyperthermia was noticed more than thirty years ago. However, combining magnetic nanoparticles with molecules of drugs in the same nanoformulation has only recently emerged as a promising tool for the application of hyperthermia with combined chemotherapy in the treatment of cancer. The main feature of this review is to present the recent advances in the development of multifunctional therapeutic nanosystems incorporating both magnetic nanoparticles and drugs, and their superior efficacy in treating cancer compared to either hyperthermia or chemotherapy as standalone therapies. The principle of magnetic fluid hyperthermia is also presented. PMID:25212238

Hervault, Aziliz; Thanh, Nguyen Th Kim

2014-10-21

304

Magnetic nanoparticle-based therapeutic agents for thermo-chemotherapy treatment of cancer  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles have been widely investigated for their great potential as mediators of heat for localised hyperthermia therapy. Nanocarriers have also attracted increasing attention due to the possibility of delivering drugs at specific locations, therefore limiting systematic effects. The enhancement of the anti-cancer effect of chemotherapy with application of concurrent hyperthermia was noticed more than thirty years ago. However, combining magnetic nanoparticles with molecules of drugs in the same nanoformulation has only recently emerged as a promising tool for the application of hyperthermia with combined chemotherapy in the treatment of cancer. The main feature of this review is to present the recent advances in the development of multifunctional therapeutic nanosystems incorporating both magnetic nanoparticles and drugs, and their superior efficacy in treating cancer compared to either hyperthermia or chemotherapy as standalone therapies. The principle of magnetic fluid hyperthermia is also presented.

Hervault, Aziliz; Thanh, Nguy&Ecirtil; N. Thá»? Kim

2014-09-01

305

Core/shell fluorescent magnetic silica-coated composite nanoparticles for bioconjugation  

NASA Astrophysics Data System (ADS)

A new class of highly fluorescent, photostable, and magnetic core/shell nanoparticles has been synthesized from a reverse microemulsion method. The obtained bifunctional nanocomposites were characterized by transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) spectrometry, photoluminescence (PL) spectrometry, and fluorescence microscopy in a magnetic field. To further improve their biocompatibility, the silica-coated nanoparticles were functionalized with amino groups. The fluorescent magnetic composite nanoparticles (FMCNPs) had a typical diameter of 50 ± 5 nm and a saturation magnetization of 3.21 emu g-1 at room temperature, and exhibited strong excitonic photoluminescence. Through activation with glutaraldehyde, the FMCNPs were successfully conjugated with goat anti-mouse immunoglobin G (GM IgG), and the bioactivity and binding specificity of the as-prepared FMCNPs-GM IgG were confirmed via immunofluorescence assays, commonly used in bioanalysis. So they are potentially useful for many applications in biolabelling, imaging, drug targeting, bioseparation and bioassays.

He, Rong; You, Xiaogang; Shao, Jun; Gao, Feng; Pan, Bifeng; Cui, Daxiang

2007-08-01

306

Magnetite and magnetite/silver core/shell nanoparticles with diluted magnet-like behavior  

SciTech Connect

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.

Garza-Navarro, Marco [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Universidad s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Torres-Castro, Alejandro, E-mail: alejandro.torrescs@uanl.edu.m [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Universidad s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon 66600 (Mexico); Gonzalez, Virgilio; Ortiz, Ubaldo [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Universidad s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon 66600 (Mexico); De la Rosa, Elder [Centro de Investigaciones en Optica, A.P. 1-948, Leon Gto. 37160 (Mexico)

2010-01-15

307

Chitosan-Coated Magnetic Nanoparticles Prepared in One Step by Reverse Microemulsion Precipitation  

PubMed Central

Chitosan-coated magnetic nanoparticles (CMNP) were obtained at 70 °C and 80 °C in a one-step method, which comprises precipitation in reverse microemulsion in the presence of low chitosan concentration in the aqueous phase. X-ray diffractometry showed that CMNP obtained at both temperatures contain a mixture of magnetite and maghemite nanoparticles with ?4.5 nm in average diameter, determined by electron microscopy, which suggests that precipitation temperature does not affect the particle size. The chitosan coating on nanoparticles was inferred from Fourier transform infrared spectrometry measurements; furthermore, the carbon concentration in the nanoparticles allowed an estimation of chitosan content in CMNP of 6%–7%. CMNP exhibit a superparamagnetic behavior with relatively high final magnetization values (?49–53 emu/g) at 20 kOe and room temperature, probably due to a higher magnetite content in the mixture of magnetic nanoparticles. In addition, a slight direct effect of precipitation temperature on magnetization was identified, which was ascribed to a possible higher degree of nanoparticles crystallinity as temperature at which they are obtained increases. Tested for Pb2+ removal from a Pb(NO3)2 aqueous solution, CMNP showed a recovery efficacy of 100%, which makes them attractive for using in heavy metals ion removal from waste water. PMID:24084716

Lopez, Raul G.; Pineda, Maria G.; Hurtado, Gilberto; de Leon, Ramon Diaz; Fernandez, Salvador; Saade, Hened; Bueno, Dario

2013-01-01

308

Magnetic behavior of Co-Mn co-doped ZnO nanoparticles  

NASA Astrophysics Data System (ADS)

Here, we report on systematic studies of the magnetic properties of Co and Mn co-doped ZnO nanoparticles prepared by a sol-gel technique. The effect of the concentration of the doping ions on the magnetic properties of Co and Mn co-doped ZnO nanoparticles is presented. X-ray diffraction characterizations (XRD) of co-doped ZnO nanoparticles are all wurtzite structure. The Zn0.96Co0.02Mn0.02O nanoparticles and Zn0.94Co0.02Mn0.04O nanoparticles display ferromagnetic behavior at room temperature. Superconducting quantum interference device (SQUID) magnetometer figures show that with the concentration of the Mn ions increased, the saturation magnetic moment (Ms) increased, and the magnetic is probably due to the co-doping of the Mn ions. Our results demonstrate that the Mn ions doping concentration play an important role in the ferromagnetic properties of Co-Mn co-doped ZnO nanoparticles at room temperature.

Li, Hengda; Liu, Xinzhong; Zheng, Zhigong

2014-12-01

309

Mouse lymphatic endothelial cell targeted probes: anti-LYVE-1 antibody-based magnetic nanoparticles  

PubMed Central

Purpose To investigate the specific targeting property of lymphatic vessel endothelial hyaluronan receptor-1 binding polyethylene glycol-coated ultrasmall superparamagnetic iron oxide (LYVE-1-PEG-USPIO) nanoparticles to mouse lymphatic endothelial cells (MLECs). Methods A ligand specific target to lymphatic vessels was selected by immunohistochemical staining on the sections of a Lewis subcutaneous transplanted tumor. The z-average hydrodynamic diameter (HD), zeta potential, and the relaxivity of PEG-USPIO and LYVE-1-PEG-USPIO nanoparticles were determined with a laser particle analyzer and magnetic resonance T2 spin echo sequence, respectively. Prussian blue staining and transmission electron microscopy (TEM) of nanoparticle labeled cells were performed to determine the nanoparticles’ binding form. Magnetic resonance imaging (MRI) was performed in vitro to evaluate the signal enhancement on the T2 spin echo sequence of the nanoparticle labeled cells. The iron content of the labeled cells after the Prussian blue staining and MRI scanning was determined by atomic absorption spectroscopy (AAS). Results The anti-LYVE-1 antibody was used as the specific ligand to synthesize the target probe to the MLECs. The mean z-average HDs of the LYVE-1-PEG-USPIO and PEG-USPIO nanoparticles were 57.42 ± 0.31 nm and 47.91 ± 0.73 nm, respectively, and the mean zeta potentials of the LYVE-1-PEG-USPIO and PEG-USPIO nanoparticles were 12.38 ± 4.87 mV and 2.57 ± 0.83 m V, respectively. The relaxivities of the LYVE-1-PEG-USPIO and PEG-USPIO nanoparticles were 185.48 mM?1s?1 and 608.32 mM?1s?1. Cells binding nanoparticles were visualized as blue granules in the Prussian blue staining. The TEM results of the labeled cells showed the specific localization of nanoparticles. The AAS results of labeled cells after the Prussian blue staining and MRI scanning showed that the LYVE-1-PEG-USPIO nanoparticles had good binding selectivity for MLECs. MRI results indicated that the PEG-USPIO and LYVE-1-PEG-USPIO nanoparticles could generate contrast on T2-weighted imaging, and the correlation between R2 and the iron content of the labeled cells was significantly positive. Conclusion This study demonstrated that LYVE-1-PEG-USPIO nanoparticles might potentially be used as an MRI contrast agent for targeting MLECs, and the magnetic properties of LYVE-1-PEG-USPIO nanoparticles were suitable for MRI. PMID:23818783

Guo, Qiu; Liu, Yi; Xu, Ke; Ren, Ke; Sun, WenGe

2013-01-01

310

Magnetic properties of double perovskite La2BMnO6 (B = Ni or Co) nanoparticles  

SciTech Connect

Double perovskite La2BMnO6 (B = Ni and Co) nanoparticles with average particle size of ~50 nm were synthesized using a facile, environmentally friendly, scalable molten-salt reaction at 700 °C in air. Their structural and morphological properties were characterized by x-ray diffraction and transmission electron microscopy. Magnetic properties were evaluated using dc magnetic M-T and M-H, and ac magnetic susceptibility versus frequency, temperature, and field. The magnetization curve shows a paramagnetic-ferromagnetic transition at TC ~275 and 220 K for La2NiMnO6 (LNMO) and La2CoMnO6 (LCMO) nanoparticles, respectively. ac susceptibility revealed that the LCMO had a single magnetic transition indicative of Co2+-O2--Mn4+ ordering, whereas the LNMO showed more complex magnetic behavior suggesting a re-entrant spin glass.

Mao, Yuanbing; Parsons, Jason; McCloy, John S.

2013-03-31

311

On chip sorting of bacterial cells using sugar-encapsulated magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Here we describe an integrated microfluidic sorting device, which utilized sugar-encapsulated magnetic nanoparticles to separate a specific strain of bacteria from a mixture solution. In our system, microfluidic devices consisting of two inlets and an electromagnet or a permanent magnet have been constructed by a soft lithography process. The magnetic field generated by either the electromagnet or the permanent magnet was strong enough to attract the bacteria bound to magnetic nanoparticles to cross the stream boundary of the laminar flow. The sorting efficiency was found to depend on both the flow rate and the strength of the magnetic field. The maximum sorting efficiency was measured to be higher than 90% and the selectivity was almost 100%. Since this microfluidic sorting device was able to separate 103 bacterial cells within 1min, it could be used for pathogenic diagnose applications.

Shih, Po-Hung; Shiu, Jau-Ye; Lin, Po-Chiao; Lin, Chun-Cheng; Veres, Teodor; Chen, Peilin

2008-04-01

312

Highly efficient antibody immobilization with multimeric protein Gs coupled magnetic silica nanoparticles  

NASA Astrophysics Data System (ADS)

This work reports the immobilization of monomeric, dimeric and trimer protein Gs onto silica magnetic nanoparticles for self-oriented antibody immobilization. To achieve this, we initially prepared the silica-coated magnetic nanoparticle having about 170 nm diameters. The surface of the silica coated magnetic nanoparticles was modified with 3- aminopropyl-trimethoxysilane (APTMS) to chemically link to multimeric protein Gs. The conjugation of amino groups on the SiO2-MNPs to cysteine tagged in multimeric protein Gs was performed using a sulfo-SMCC coupling procedure. The binding efficiencies of monomer, dimer and trimer were 77 %, 67 % and 55 % respectively. However, the efficiencies of antibody immobilization were 70 %, 83 % and 95 % for monomeric, dimeric and trimeric protein G, respectively. To prove the enhancement of accessibility by using multimeric protein G, FITC labeled goat-anti-mouse IgG was treated to mouse IgG immobilized magnetic silica nanoparticles through multimeric protein G. FITC labeled goat anti-mouse IgGs were more easily bound to mouse IgG immobilized by trimeric protein G than others. Finally protein G bound silica magnetic nanoparticles were utilized to develop highly sensitive immunoassay to detect hepatitis B antigen.

Lee, J. H.; Choi, H. K.; Chang, J. H.

2011-10-01

313

Synthesis, characterization, and fabrication of magnetic nanoparticles for low energy loss applications  

NASA Astrophysics Data System (ADS)

It is important to increase operating frequency of power electronics for miniaturization of components. Magnetic materials are used as inductor cores to increase inductance proportional to their magnetic permeability. However, traditional magnetic materials are not used at high frequency (100MHz) because of large hysteresis and eddy current loss. Superparamagnetic nanoparticles are good candidates to resolve these problems because they have zero hysteresis loss. In addition, eddy currents can be reduced due to their high electric resistivity originating from the organic ligands on the surface. Magnetic nanoparticles such as NiFe2O4, Ni1-xZnxFe2O4, MnFe3O4 and ZnFe2O4 have been synthesized via high temperature thermal decomposition method and can be tuned to desired size, shape and chemical composition. To understand structural and magnetic properties of nanoparticles, the nanoparticles have been characterized by TEM, SQUID, PPMS, and Network Analyzer. UV-induced polymerization and pressing method have been implemented for film deposition. Finally, AC susceptibility of the nanoparticle film have been measured and discussed for low energy-loss applications.

Yun, Hongseok; Chen, Jun; Doan-Nguyen, Vicky; Kikkawa, James; Murray, Christopher

2013-03-01

314

?-Fe2O3 nanoparticles dispersed in porous Vycor glass: A magnetically diluted integrated system  

NASA Astrophysics Data System (ADS)

An investigation of the effect of interparticle interaction and particle size distribution has been carried out on iron oxide nanoparticles dispersed into porous Vycor glass. ?-Fe2O3 nanoparticles dispersed into monoliths of Vycor glass were obtained using impregnation-decomposition cycles through the single-source metallo-organic decomposition process. Magnetic properties were investigated by ac magnetic susceptibility measurements, as a function of temperature at different frequencies, by measuring zero-field-cooled and field-cooled magnetization curves and by constructing hysteresis loops at different temperatures. A log-normal size distribution of monodomain nanoparticles has been deduced from the analysis of the magnetization curves. F57e Mössbauer spectroscopy was also employed for investigating the magnetic behavior as a function of nanoparticle size. The systems exhibit typical superparamagnetic behaviors with a wide particle size distribution that can be changed without significantly affecting the interparticle interaction. The experimental data are discussed in terms of the evolution of the particle size distribution with the number of impregnation-decomposition cycles used for preparing the nanoparticles.

Cangussu, Danielle; Nunes, Wallace Castro; Corrêa, Heberton Luis da Silva; Macedo, Waldemar Augusto de Almeida; Knobel, Marcelo; Alves, Oswaldo Luiz; Filho, Antônio Gomes Souza; Mazali, Italo Odone

2009-01-01

315

Structural responses of cells to intracellular magnetic force induced by superparamagnetic iron oxide nanoparticles.  

PubMed

In this paper, we study the effects of intracellular force on human umbilical vein endothelial cells. We generated intracellular force on endothelial cells under different magnetic fields using the cell uptake of superparamagnetic iron oxide nanoparticles. Cell responses to intracellular force were observed using fluorescent microscopy. Our results indicated that nanoparticles were taken up by the cell by endocytosis and were deposited in lysosomes. Nanoparticles and lysosomes inside the cell could be relocated by the application of a magnetic force. The intracellular magnetic force could also be used to accelerate cell migration by adjusting the magnetic fields and giving the cell free culture space. No cytotoxicity of nanoparticles was found in our experiments. By comparing intracellular relocalization with migration of the whole cell, we obtained a better understanding of the self-defence mechanisms of cells based on their mechanical properties. Based on the promising mechanical properties and low cytotoxicity of our magnetic nanoparticles, their potential applications in cytomechanics and cell patterning are discussed. PMID:24336693

Shen, Han; Tong, Sheng; Bao, Gang; Wang, Biao

2014-02-01

316

Structural and magnetic properties of CoO-Pt core-shell nanoparticles  

NASA Astrophysics Data System (ADS)

Using microemulsion methods, CoO-Pt core-shell nanoparticles, with diameters of nominally 4 nm, were synthesized and characterized by high-resolution transmission electron microscopy and a suite of x-ray spectroscopies, including diffraction, absorption, absorption near-edge structure, and extended absorption fine structure, which confirmed the existence of CoO cores and pure Pt surface layers. Using a commercial magnetometer, the ac and dc magnetic properties were investigated over a range of temperature (2 K ?T? 300 K), magnetic field (?50 kOe), and frequency (?1 kHz). The data indicate the presence of two different magnetic regimes whose onsets are identified by two maxima in the magnetic signals, with a narrow maximum centered at 6 K and a large one centered at 37 K. The magnetic responses in these two regimes exhibit different frequency dependencies, where the maximum at high temperature follows a Vogel-Fulcher law, indicating a superparamagnetic blocking of interacting nanoparticle moments and the maximum at low temperature possesses a power-law response characteristic of a collective freezing of the nanoparticle moments in a superspin glass state. This co-existence of blocking and freezing behaviors is consistent with the nanoparticles possessing an antiferromagnetically ordered core, with an uncompensated magnetic moment, and a magnetically disordered interlayer between the CoO core and the Pt shell.

ZeleÅáková, Adriana; ZeleÅák, Vladimir; Michalík, Štefan; Ková?, Jozef; Meisel, Mark W.

2014-03-01

317

Optical And Magnetic Properties Of Monodispersed ?-Fe2O3 Nanoparticle Aggregates  

NASA Astrophysics Data System (ADS)

Monodispersed ?-Fe2O3 nanoparticle aggregates with diameter ˜15 nm were successfully prepared by polyol process. The finite size effects in ?-Fe2O3 nanoparticles were studied by X-ray diffraction, transmission electron microscopy, diffuse reflectance spectroscopy and ac-magnetic susceptibility. The optical band gap of ?-Fe2O3 nanoparticles was significantly reduced compared to that of precursor. The ?-Fe2O3 nanoparticles exhibited superparamagnetic behavior at room temperature, with blocking temperature TB = 100 K at 313 Hz and its value shifted to 124 K at 3.13 KHz. Analysis of ac-magnetic susceptibility data gives a superparamagnetic relaxation time (?o) of 4×10-9 s.

Ramachandran, B.; Rao, M. S. Ramachandra

2008-04-01

318

Synthesis and characterization of magnetic nanoparticles embedded in polyvinyl pyrrolidone nanofiber film by electrospinning method  

NASA Astrophysics Data System (ADS)

We fabricated magnetic nanofiber films by manufacturing the nanoparticles with the polyol process followed by the electrospinning process to combine them into a thin film. The magnetite (Fe3O4) nanoparticles with mean crystallite size of 6-8 nm were synthesized through reduction of iron (II) acetate in the polyols and using polyvinyl pyrrolidone (PVP) as the protecting agent. The PVP-coated Fe3O4 nanoparticles were dispersed into PVP ethanol solution and then electrospun directly to make nanofiber films. The diameters of fibers range between 200-400 nm, and the film thickness is about 50 ?m. The Fe3O4 nanoparticles show a saturation magnetization of 36.6 emu/g, and together with the nanofiber films display a superparamagnetic behavior.

Lin, Chun-Rong; Tsai, Tsu-Chi; Chung, Max; Lu, Shih-Zong

2009-04-01

319

Alzheimer’s Disease: Pathophysiology and Applications of Magnetic Nanoparticles as MRI Theranostic Agents  

PubMed Central

Alzheimer’s disease (AD) is the most common form of dementia. During the recent decade, nanotechnology has been widely considered, as a promising tool, for theranosis (diagnosis and therapy) of AD. Here we first discuss pathophysiology and characteristics of AD with a focus on the amyloid cascade hypothesis. Then magnetic nanoparticles (MNPs) and recent works on their applications in AD, focusing on the superparamagnetic iron oxide nanoparticles (SPIONs), are reviewed. Furthermore, the amyloid–nanoparticle interaction is highlighted, with the scope to be highly considered by the scientists aiming for diagnostics and/or treatment of AD employing nanoparticles. Furthermore, recent findings on the “ignored” parameters (e.g., effect of protein “corona” at the surface of nanoparticles on amyloid-? (A?) fibrillation process) are discussed. PMID:24024702

2013-01-01

320

Nanoparticle-Based Systems for T1-Weighted Magnetic Resonance Imaging Contrast Agents  

PubMed Central

Because magnetic resonance imaging (MRI) contrast agents play a vital role in diagnosing diseases, demand for new MRI contrast agents, with an enhanced sensitivity and advanced functionalities, is very high. During the past decade, various inorganic nanoparticles have been used as MRI contrast agents due to their unique properties, such as large surface area, easy surface functionalization, excellent contrasting effect, and other size-dependent properties. This review provides an overview of recent progress in the development of nanoparticle-based T1-weighted MRI contrast agents. The chemical synthesis of the nanoparticle-based contrast agents and their potential applications were discussed and summarized. In addition, the recent development in nanoparticle-based multimodal contrast agents including T1-weighted MRI/computed X-ray tomography (CT) and T1-weighted MRI/optical were also described, since nanoparticles may curtail the shortcomings of single mode contrast agents in diagnostic and clinical settings by synergistically incorporating functionality. PMID:23698781

Zhu, Derong; Liu, Fuyao; Ma, Lina; Liu, Dianjun; Wang, Zhenxin

2013-01-01

321

Nanoparticles of magnetic ferric oxides encapsulated with poly(D,L latide-co-glycolide) and their applications to magnetic resonance imaging contrast agent  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles of Fe 3O 4 encapsulated with Poly(D,L lactide-co-glycolide) (PLGA) were prepared for magnetic resonance imaging (MRI) contrast agent by using an emulsification-diffusion method. In this study, we have investigated the effects of homogenizer and agitator speed on the nanoparticles formation and the magnetic properties of ferrofluid nanoparticles encapsulated with PLGA with varying the ferromagnetic particle size from 10 to 180 nm. We have confirmed that the ferrofluid nanoparticles encapsulated with PLGA could be utilized as an MRI contrast agent from experiments in animal tissue.

Lee, Seung-Jun; Jeong, Jong-Ryul; Shin, Sung-Chul; Kim, Jin-Chul; Chang, Young-Hwan; Chang, Yong-Min; Kim, Jong-Duk

2004-05-01

322

Real-time magnetic nanothermometry: The use of magnetization of magnetic nanoparticles assessed under low frequency triangle-wave magnetic fields  

NASA Astrophysics Data System (ADS)

In this study, we propose and demonstrate the usefulness of employing time-varying magnetization of a magnetic nanoparticle (MNP) based sample, induced by low frequency (f = 25 Hz) triangular-wave magnetic field, to achieve the approach of real-time recording of magnetization curve, which allows precise and noninvasive temperature probing with real-time performance. Moreover, the present report introduces the design and performed the test of a detection system for accurate and real-time recording of the magnetization curve of MNP-based samples. We found that by employing the magnetization curve of a magnetic fluid sample containing magnetite nanoparticles of about 30 nm in diameter the accuracy of the temperature probing is about 0.32 K (0.1% relative accuracy), with response time of 1 s. Furthermore, an increase in response time from 1 to 8 s improves the accuracy of temperature probing from 0.32 to 0.20 K. Finally, we envisage that breakthroughs in clinical hyperthermia, targeted drug delivery and basic cell research can be accomplished while using the approach reported in this study.

Zhong, Jing; Liu, Wenzhong; Jiang, Ling; Yang, Ming; Morais, Paulo Cesar

2014-09-01

323

Magnetic phase diagram of interacting nanoparticle systems under the mean-field model  

NASA Astrophysics Data System (ADS)

The disordered random-anisotropy magnetic nanoparticle systems with competing dipolar interactions and ferromagnetic exchange couplings are investigated by Monte Carlo simulations. Superspin glass (SSG) and superferromagnetic (SFM) behaviors are found at low temperatures depending on the interactions. Based on the mean-field approximation, the Curie-Weiss temperature TCW = 0 is suggested as the phase boundary between the SSG systems and the SFM systems, which is evidenced by the spontaneous magnetizations and relaxations. The magnetic phase diagram is plotted.

Mao, Zhongquan; Chen, Xi

2011-06-01

324

[Experience with the use of magnetic nanoparticles in medicine and prospects for their application in otorhinolaringology].  

PubMed

The literature review of the methods for application of magnetic nanoparticles in different fields of medicine is presented. The paper summarizes the 40 year-long experience of Russian and foreign scientists with the use of magnetic suspensions, liquids, and particles with magnetic carriers from 10 to 1000 nm in diameter. Results of recent studies are presented, prospects for the development and application of nanomedical techniques in otorhinolaringology are discussed. PMID:19491801

Dobretsov, K G; Afon'kin, V Iu; Stoliar, S V; Ladygina, V P; Sipkin, A V; Lopatin, A S

2009-01-01

325

Antiferromagnetic Nanoparticles of Iron Oxides: Their Magnetic Properties, and the Effects of Aggregation and Interparticle Interactions  

Microsoft Academic Search

Antiferromagnetic materials such as a-Fe2O3 (hematite), a-FeOOH (goethite) and ferrihydrite, are commonly found in geological environments, but they have typically attracted limited attention in magnetic studies, because their sublattice magnetizations are aligned antiparallel and hence particles of these materials is often thought to have negligible magnetic moments. A number of studies have, however, revealed that nanoparticles of antiferromagnetic materials show

C. Frandsen

2007-01-01

326

Magnetic resonance imaging of multifunctional pluronic stabilized iron-oxide nanoparticles in tumor-bearing mice  

Microsoft Academic Search

We are investigating the magnetic resonance imaging characteristics of magnetic nanoparticles (MNPs) that consist of an iron-oxide magnetic core coated with oleic acid (OA), then stabilized with a pluronic or tetronic block copolymer. Since pluronics and tetronics vary structurally, and also in the ratio of hydrophobic (poly[propylene oxide]) and hydrophilic (poly[ethylene oxide]) segments in the polymer chain and in molecular

Tapan K. Jain; Susan P. Foy; Bernadette Erokwu; Sanja Dimitrijevic; Christopher A. Flask; Vinod Labhasetwar

2009-01-01

327

Nanoparticle-supported and magnetically recoverable palladium (Pd) catalyst: a selective and sustainable oxidation protocol with high turnover number  

EPA Science Inventory

A magnetic nanoparticle-supported ruthenium hydroxide catalyst was readily prepared from inexpensive starting materials and shown to catalyze hydration of nitriles with excellent yield in benign aqueous medium. Catalyst recovery using an external magnetic field, superior activity...

328

Fe@Ag core–shell nanoparticles with both sensitive plasmonic properties and tunable magnetism  

Microsoft Academic Search

Monodisperse Fe@Ag core–shell nanoparticles with relatively uniform Fe cores and Ag shells have been successfully fabricated by a seed mediated method in a two-step reducing process, and then characterized by electron microscopy techniques (HRTEM, EDX), X-ray diffraction (XRD), UV–vis spectroscopy?and magnetometry. The results demonstrate unique optical and magnetic properties for Fe@Ag core–shell nanoparticles. The surface plasmon resonance of Fe@Ag core–shell

Liying Lu; Wentao Zhang; Dong Wang; Xiaoguang Xu; Jun Miao; Yong Jiang

2010-01-01

329

A combined theoretical and in vitro modeling approach for predicting the magnetic capture and retention of magnetic nanoparticles in vivo  

PubMed Central

Magnetic nanoparticles (MNP) continue to draw considerable attention as potential diagnostic and therapeutic tools in the fight against cancer. Although many interacting forces present themselves during magnetic targeting of MNP to tumors, most theoretical considerations of this process ignore all except for the magnetic and drag forces. Our validation of a simple in vitro model against in vivo data, and subsequent reproduction of the in vitro results with a theoretical model indicated that these two forces do indeed dominate the magnetic capture of MNP. However, because nanoparticles can be subject to aggregation, and large MNP experience an increased magnetic force, the effects of surface forces on MNP stability cannot be ignored. We accounted for the aggregating surface forces simply by measuring the size of MNP retained from flow by magnetic fields, and utilized this size in the mathematical model. This presumably accounted for all particle-particle interactions, including those between magnetic dipoles. Thus, our “corrected” mathematical model provided a reasonable estimate of not only fractional MNP retention, but also predicted the regions of accumulation in a simulated capillary. Furthermore, the model was also utilized to calculate the effects of MNP size and spatial location, relative to the magnet, on targeting of MNPs to tumors. This combination of an in vitro model with a theoretical model could potentially assist with parametric evaluations of magnetic targeting, and enable rapid enhancement and optimization of magnetic targeting methodologies. PMID:21295085

David, Allan E.; Cole, Adam J.; Chertok, Beata; Park, Yoon Shin; Yang, Victor C.

2011-01-01

330

The interaction of polymer-coated magnetic nanoparticles with seawater.  

PubMed

Laboratory studies were conducted to evaluate the interaction between bare and polymer-coated magnetic nanoparticles (MNPs) with various environmentally relevant carrying solutions including natural oceanic seawater with and without addition of algal exopolymeric substances (EPS). The MNPs were coated with three different stabilising agents, namely gum Arabic (GA-MNP), dextran (D-MNP) and carboxymethyl-dextran (CMD-MNP). The colloidal stability of the suspensions was evaluated over 48 h and we demonstrated that: (i) hydrodynamic diameters increased over time regardless of carrying solution for all MNPs except the GA-coated ones; however, the relative changes were carrying solution- and coat-dependent; (ii) polydispersity indexes of the freshly suspended MNPs are below 0.5 for all coated MNPs, unlike the much higher values obtained for the uncoated MNPs; (iii) freshly prepared MNP suspensions (both coated and uncoated) in Milli-Q (MQ) water show high colloidal stability as indicated by zeta-potential values below -30 mV, which however decrease in absolute value within 48 h for all MNPs regardless of carrying solution; (iv) EPS seems to "stabilise" the GA-coated and the CMD-coated MNPs, but not the uncoated or the D-coated MNPs, which form larger aggregates within 48 h; (v) despite this aggregation, iron (Fe)-leaching from MNPs is sustained over 48h, but remained within the range of 3-9% of the total iron-content of the initially added MNPs regardless of suspension media and capping agent. The environmental implications of our findings and biotechnological applicability of MNPs are discussed. PMID:24315028

Kadar, Enikö; Batalha, Iris L; Fisher, Andrew; Roque, Ana Cecília A

2014-07-15

331

One-Pot Synthesis of CO2 -Responsive Magnetic Nanoparticles with Switchable Hydrophilicity.  

PubMed

CO2 -responsive nanoparticles have been attracted increasing interest due to their benign reactions with CO2 that give them gas-switchable properties, which can be easily reversed by mild heating or purging with inert gases. In this work, we have prepared CO2 -responsive magnetic nanoparticles in a simple one-pot polyol synthesis using diaminoalkanes as the surfactant. The as-synthesized nanoparticles show excellent reversible aggregation and dispersion in response to alternating purging of N2 and CO2 at room temperature. We found that, among the diaminoalkanes with different chain lengths, 1,8-diaminooctane is the best candidate for the synthesis of CO2 -responsive nanoparticles, since it allows good dispersity of the nanoparticles after charging with CO2 and also provides effective aggregation and separation following N2 purging. Moreover, the self-assembly of 1,8-diaminooctane-functionalized nanoparticles can be controlled to form linear aggregates with the assistance of N2 and an external magnetic field, demonstrating an effective response to dual stimuli. This work paves the way for the direct synthesis of a wide range of CO2 -responsive nanoparticles. PMID:25196397

Chen, Shucheng; Guo, Chun Xian; Zhao, Qipeng; Lu, Xianmao

2014-10-20

332

PEGylated versus non-PEGylated magnetic nanoparticles as camptothecin delivery system  

PubMed Central

Summary Camptothecin (CPT; (S)-(+)-4-ethyl-4-hydroxy-1H-pyrano[3',4':6,7]indolizino[1,2-b]quinoline-3,14-(4H,12H)-dione) is a highly cytotoxic natural alkaloid that has not yet found use as chemotherapeutic agent due to its poor water-solubility and chemical instability and, as a consequence, no effective administration means have been designed. In this work, camptothecin has been successfully loaded into iron oxide superparamagnetic nanoparticles with an average size of 14 nm. It was found that surface modification of the nanoparticles by polyethylene glycol enables loading a large amount of camptothecin. While the unloaded nanoparticles do not induce apoptosis in the H460 lung cancer cell line, the camptothecin-loaded nanoparticle formulations exhibit remarkable pro-apoptotic activity. These results indicate that camptothecin retains its biological activity after loading onto the magnetic nanoparticles. The proposed materials represent novel materials based on naturally occurring bioactive molecules loaded onto nanoparticles to be used as chemotherapeutic formulations. The procedure seems apt to be extended to other active molecules extracted from natural products. In addition, these materials offer the potential of being further implemented for combined imaging and therapeutics, as magnetic nanoparticles are known to be multifunctional tools for biomedicine. PMID:25247114

Castillo, Paula M; de la Mata, Mario; Casula, Maria F; Sánchez-Alcázar, José A

2014-01-01

333

Magnetic properties of Fe(x)Pt(y)Au(100-x-y) nanoparticles.  

PubMed

Fe(x)Pt(y)Au(100-x-y) nanoparticles of size 3.5 nm were prepared by polyol reduction of platinum acetylacetonate and gold acetate and the thermal decomposition of iron pentacarbonyl. The as-synthesized nanoparticles with disordered fcc structure were then heat treated to transform to the L1(0) structure with high magnetocrystalline anisotropy. By tuning the stoichiometry of the Fe(x)Pt(y)Au(100-x-y) nanoparticles, the phase transition temperature was reduced by more than 200 degrees C. After the annealing 500 degrees C, for instance, the highest coercivity of 18 kOe was obtained from the Fe51Pt36Au13 nanoparticles which is substantially higher compared to 2 kOe for Fe51Pt49 nanoparticles annealed at the same temperature. In addition to the high coercivity, the saturation magnetization value obtained from Fe51Pt36Au13 nanoparticles was 47 emu/g which is similar to that for the Fe51Pt49 nanoparticles, indicating that there is no trade-off between the coercivity and the saturation magnetization upon Au doping. PMID:20358888

Nandwana, Vikas; Chaubey, Girija S; Zhang, Yunpeng; Liu, J Ping

2010-05-01

334

Room temperature ferromagnetism in non-magnetic doped TiO2 nanoparticles  

NASA Astrophysics Data System (ADS)

Room-temperature ferromagnetism in non-magnetic doped TiO2 semiconductor nanoparticles is analyzed in the present work. Undoped and N-doped TiO2 nanoparticles were obtained employing sol-gel procedure using urea as the nitrogen source. The obtained gels were first dried at 70 °C and afterwards calcined in air at 300 °C. A residual carbon concentration was retained in the samples as a consequence of the organic decomposition process. Post-annealing treatments at 300 °C under air and vacuum conditions were also performed. The crystallographic structure of nanoparticles was analyzed by X-ray diffraction, obtaining a single anatase crystalline phase after the calcinations (mean nanoparticle diameters around 5-8 nm). SQUID magnetometry was employed to analyze the magnetic response of the samples. Whereas for the undoped samples synthesized with hydrolysis rate h = 6, paramagnetic like behavior is observed at room temperature, the N-doped nanoparticles (h = 3) show a weak ferromagnetic response (saturation magnetization ?10-3 emu/g). Moreover, a clear reinforcement of the room-temperature ferromagnetism response is found with the post-annealing treatments, in particular that performed in vacuum. Thus, the results indicate the dominant role of the oxygen stoichiometry and the oxygen vacancies in the room temperature ferromagnetic response of these TiO2 nanoparticles.

Gómez-Polo, C.; Larumbe, S.; Pastor, J. M.

2013-05-01

335

Understanding magnetic nanoparticle osteoblast receptor-mediated endocytosis using experiments and modeling  

NASA Astrophysics Data System (ADS)

Iron oxide nanoparticles are promising candidates for controlling drug delivery through an external magnetic force to treat a wide range of diseases, including osteoporosis. Previous studies have demonstrated that in the presence of hydroxyapatite coated magnetite (Fe3O4) nanoparticles, osteoblast (or bone forming cell) proliferation and long-term functions (such as calcium deposition) were significantly enhanced. Hydroxyapatite is the major inorganic component of bone. As a further attempt to understand why, in the current study, the uptake of such nanoparticles into osteoblasts was experimentally investigated and mathematically modeled. Magnetite nanoparticles were synthesized using a co-precipitation method and were coated with hydroxyapatite. A cellular uptake experiment at low temperatures indicated that receptor-mediated endocytosis contributed to the internalization of the magnetic nanoparticles into osteoblasts. A model was further developed to explain the uptake of magnetic nanoparticles into osteoblasts using receptor-mediated endocytosis. This model may explain the internalization of hydroxyapatite into osteoblasts to elevate intracellular calcium levels necessary to promote osteoblast functions to treat a wide range of orthopedic problems, including osteoporosis.

Tran, Nhiem; Webster, Thomas J.

2013-05-01

336

Understanding magnetic nanoparticle osteoblast receptor-mediated endocytosis using experiments and modeling.  

PubMed

Iron oxide nanoparticles are promising candidates for controlling drug delivery through an external magnetic force to treat a wide range of diseases, including osteoporosis. Previous studies have demonstrated that in the presence of hydroxyapatite coated magnetite (Fe3O4) nanoparticles, osteoblast (or bone forming cell) proliferation and long-term functions (such as calcium deposition) were significantly enhanced. Hydroxyapatite is the major inorganic component of bone. As a further attempt to understand why, in the current study, the uptake of such nanoparticles into osteoblasts was experimentally investigated and mathematically modeled. Magnetite nanoparticles were synthesized using a co-precipitation method and were coated with hydroxyapatite. A cellular uptake experiment at low temperatures indicated that receptor-mediated endocytosis contributed to the internalization of the magnetic nanoparticles into osteoblasts. A model was further developed to explain the uptake of magnetic nanoparticles into osteoblasts using receptor-mediated endocytosis. This model may explain the internalization of hydroxyapatite into osteoblasts to elevate intracellular calcium levels necessary to promote osteoblast functions to treat a wide range of orthopedic problems, including osteoporosis. PMID:23574992

Tran, Nhiem; Webster, Thomas J

2013-05-10

337

Large scale synthesis of FeS coated Fe nanoparticles as reusable magnetic photocatalysts  

NASA Astrophysics Data System (ADS)

The FeS coated Fe nanoparticles were prepared by using high temperature reactions between the commercial Fe nanoparticles and the S powders in a sealed quartz tube. The simple method developed in this work is effective for large scale synthesis of FeS/Fe nanoparticles with tunable shell/core structures, which can be obtained by controlling the atomic ratio of Fe to S. The structural, magnetic and photocatalytic properties of the nanoparticles were investigated systematically. The good photocatalytic performance originating from the FeS shell in degradation of methylene blue under visible light and the high saturation magnetization originating from the ferromagnetic Fe core make the FeS/Fe nanoparticles a good photocatalyst that can be collected and recycled easily with a magnet. An exchange bias up to 11 mT induced in Fe by FeS was observed in the Fe/FeS nanoparticles with ferro/antiferromagnetic interfaces. The enhanced coercivity up to 32 mT was ascribed to the size effect of Fe core.

Feng, He; Si, Ping-Zhan; Xiao, Xiao-Fei; Jin, Chen-Hao; Yu, Sen-Jiang; Li, Zheng-Fa; Ge, Hong-Liang

2013-09-01

338

Simulating Magnetic Nanoparticle Behavior in Low-field MRI under Transverse Rotating Fields and Imposed Fluid Flow  

PubMed Central

In the presence of alternating-sinusoidal or rotating magnetic fields, magnetic nanoparticles will act to realign their magnetic moment with the applied magnetic field. The realignment is characterized by the nanoparticle’s time constant, ?. As the magnetic field frequency is increased, the nanoparticle’s magnetic moment lags the applied magnetic field at a constant angle for a given frequency, ?, in rad/s. Associated with this misalignment is a power dissipation that increases the bulk magnetic fluid’s temperature which has been utilized as a method of magnetic nanoparticle hyperthermia, particularly suited for cancer in low-perfusion tissue (e.g., breast) where temperature increases of between 4°C and 7°C above the ambient in vivo temperature cause tumor hyperthermia. This work examines the rise in the magnetic fluid’s temperature in the MRI environment which is characterized by a large DC field, B0. Theoretical analysis and simulation is used to predict the effect of both alternating-sinusoidal and rotating magnetic fields transverse to B0. Results are presented for the expected temperature increase in small tumors (~1 cm radius) over an appropriate range of magnetic fluid concentrations (0.002 to 0.01 solid volume fraction) and nanoparticle radii (1 to 10 nm). The results indicate that significant heating can take place, even in low-field MRI systems where magnetic fluid saturation is not significant, with careful The goal of this work is to examine, by means of analysis and simulation, the concept of interactive fluid magnetization using the dynamic behavior of superparamagnetic iron oxide nanoparticle suspensions in the MRI environment. In addition to the usual magnetic fields associated with MRI, a rotating magnetic field is applied transverse to the main B0 field of the MRI. Additional or modified magnetic fields have been previously proposed for hyperthermia and targeted drug delivery within MRI. Analytical predictions and numerical simulations of the transverse rotating magnetic field in the presence of B0 are investigated to demonstrate the effect of ?, the rotating field frequency, and the magnetic field amplitude on the fluid suspension magnetization. The transverse magnetization due to the rotating transverse field shows strong dependence on the characteristic time constant of the fluid suspension, ?. The analysis shows that as the rotating field frequency increases so that ?? approaches unity, the transverse fluid magnetization vector is significantly non-aligned with the applied rotating field and the magnetization’s magnitude is a strong function of the field frequency. In this frequency range, the fluid’s transverse magnetization is controlled by the applied field which is determined by the operator. The phenomenon, which is due to the physical rotation of the magnetic nanoparticles in the suspension, is demonstrated analytically when the nanoparticles are present in high concentrations (1 to 3% solid volume fractions) more typical of hyperthermia rather than in clinical imaging applications, and in low MRI field strengths (such as open MRI systems), where the magnetic nanoparticles are not magnetically saturated. The effect of imposed Poiseuille flow in a planar channel geometry and changing nanoparticle concentration is examined. The work represents the first known attempt to analyze the dynamic behavior of magnetic nanoparticles in the MRI environment including the effects of the magnetic nanoparticle spin-velocity. It is shown that the magnitude of the transverse magnetization is a strong function of the rotating transverse field frequency. Interactive fluid magnetization effects are predicted due to non-uniform fluid magnetization in planar Poiseuille flow with high nanoparticle concentrations. PMID:20625540

Wald, L.L.; Adalsteinsson, E.; Zahn, M.

2010-01-01

339

Transcellular Transport of Heparin-coated Magnetic Iron Oxide Nanoparticles (Hep-MION) Under the Influence of an Applied Magnetic Field.  

PubMed

In this study, magnetic iron oxide nanoparticles coated with heparin (Hep-MION) were synthesized and the transcellular transport of the nanoparticles across epithelial cell monolayers on porous polyester membranes was investigated. An externally applied magnetic field facilitated the transport of the Hep-MION across cell monolayers. However, high Hep-MION concentrations led to an increased aggregation of nanoparticles on the cell monolayer after application of the magnetic field. Our results indicate that magnetic guidance of Hep-MION most effectively promotes transcellular transport under conditions that minimize formation of magnetically-induced nanoparticle aggregates. Across cell monolayers, the magnet's attraction led to the greatest increase in mass transport rate in dilute dispersions and in high serum concentrations, suggesting that magnetic guidance may be useful for in vivo targeting of Hep-MION. PMID:21152371

Min, Kyoung Ah; Yu, Faquan; Yang, Victor C; Zhang, Xinyuan; Rosania, Gus R

2010-04-26

340

Iron-based soft magnetic composites with MnZn ferrite nanoparticles coating obtained by solgel method  

E-print Network

Iron-based soft magnetic composites with Mn­Zn ferrite nanoparticles coating obtained by sol focuses on iron-based soft magnetic composites which were synthesized by utilizing Mn­Zn ferrite nanoparticles to coat iron powder. The nanocrystalline iron powders, with an average particle diameter of 20 nm

Volinsky, Alex A.

341

Core-shell-corona-structured polyelectrolyte brushes-grafting magnetic nanoparticles for water harvesting.  

PubMed

A novel superhydrophilic material, charged polymer brushes-grafted magnetic core-shell-corona composite nanoparticles (Fe3O4@SiO2@PSPMA), was developed to harvest water through the hydration effect. Because of both the strong hydration capability and the good swelling performance, the negatively charged polymer brushes, PSPMA brushes, endow the composite nanoparticles with superhydrophilicity and a good water-absorbing performance like a sponge, while the magnetic Fe3O4 cores allow easy separation of Fe3O4@SiO2@PSPMA nanoparticles with absorbed water from oil/water mixture under an external magnetic field. The functional particles have the capability of harvesting water droplets whether floating on an oil surface or in the oil. This water-absorbing material uses selective wettability to harvest water and achieve oil-water separation and may be useful in finding novel approaches for recycling water from sewage and removing water in the petroleum industry. PMID:24955817

Liu, Guoqiang; Cai, Meirong; Wang, Xiaolong; Zhou, Feng; Liu, Weimin

2014-07-23

342

Size distribution of magnetic iron oxide nanoparticles using Warren-Averbach XRD analysis  

NASA Astrophysics Data System (ADS)

We use the Fourier transform based Warren-Averbach (WA) analysis to separate the contributions of X-ray diffraction (XRD) profile broadening due to crystallite size and microstrain for magnetic iron oxide nanoparticles. The profile shape of the column length distribution, obtained from WA analysis, is used to analyze the shape of the magnetic iron oxide nanoparticles. From the column length distribution, the crystallite size and its distribution are estimated for these nanoparticles which are compared with size distribution obtained from dynamic light scattering measurements. The crystallite size and size distribution of crystallites obtained from WA analysis are explained based on the experimental parameters employed in preparation of these magnetic iron oxide nanoparticles. The variation of volume weighted diameter (Dv, from WA analysis) with saturation magnetization (Ms) fits well to a core shell model wherein it is known that Ms=Mbulk(1-6g/Dv) with Mbulk as bulk magnetization of iron oxide and g as magnetic shell disorder thickness.

Mahadevan, S.; Behera, S. P.; Gnanaprakash, G.; Jayakumar, T.; Philip, J.; Rao, B. P. C.

2012-07-01

343

Induction heating studies of dextran coated MgFe2O4 nanoparticles for magnetic hyperthermia.  

PubMed

MgFe(2)O(4) nanoparticles with sizes around 20 nm have been prepared by a combustion method and functionalized with dextran for their possible applications in magnetic particle hyperthermia. The induction heating study of these nanoparticles at different magnetic field amplitudes, from 6.7 kA m(-1) to 26.7 kA m(-1), showed self-heating temperature rise up to 50.25 °C and 73.32 °C (at 5 mg mL(-1) and 10 mg mL(-1) concentrations in water respectively) which was primarily thought to be due to hysteresis losses activated by an AC magnetic field. The dextran coated nanoparticles showed a maximum specific absorption rate (SAR) of about 85.57 W g(-1) at 26.7 kA m(-1) (265 kHz). Dextran coated nanoparticles at concentrations below 1.8 mg mL(-1) exhibit good viability above 86% on mice fibroblast L929 cells. The results suggest that combustion synthesized MgFe(2)O(4) nanoparticles coated with dextran can be used as potential heating agents in magnetic particle hyperthermia. Uncoated and dextran coated samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric-differential thermal analysis (TG-DTA) and zeta potential-DLS studies. PMID:23138108

Khot, V M; Salunkhe, A B; Thorat, N D; Ningthoujam, R S; Pawar, S H

2013-01-28

344

Immobilized protease on the magnetic nanoparticles used for the hydrolysis of rapeseed meals  

NASA Astrophysics Data System (ADS)

(3-aminopropl) triethoxysilaneand modified magnetic nanoparticles with the average diameter of 25.4 nm were synthesized in water-phase co-precipitation method. And then these nanoparticles were covalently coupled with alkaline protease as enzyme carrier by using 1,4-phenylene diisothlocyanate as coupling agent. Experiments showed that the immobilized protease can keep the catalytic bioactivity, which can reach to 47.8% when casein was served as substrate. Results showed that the catalytic activity of immobilized protease on these magnetic nanoparticles could retain 98.63±2.37% after 60 days. And it is more stable than the free protease during the shelf-life test. The enzyme reaction conditions such as optimum reaction temperature and pH are the same as free protease. Furthermore, mix-and-separate experiments showed that the immobilized protease could be recycled through the magnetic nanoparticles after the biocatalysis process. When the rapeseed meals were used as substrate, the degree of hydrolysis of immobilized alkaline protease achieved 9.86%, while it was 10.41% for the free protease. The macromolecular proteins of rapeseed meals were hydrolyzed by immobilized protease into small molecules such as polypeptides or amino acids. Thus, a novel efficient and economic way for the recycling of enzymes in the application of continuous production of active peptides was provided based on these magnetic nanoparticles.

Jin, Xin; Li, Ju-Fang; Huang, Ping-Ying; Dong, Xu-Yan; Guo, Lu-Lu; Yang, Liang; Cao, Yuan-Cheng; Wei, Fang; Zhao, Yuan-Di; Chen, Hong

2010-07-01

345

Formation of magnetic nanoparticles studied during the initial synthesis stage  

NASA Astrophysics Data System (ADS)

The formation of iron oxide nanoparticles in course of a sol-gel preparation process was traced by UV/Vis and 57Fe Mössbauer absorption spectroscopy. Samples were extracted at different stages of the reaction. While spectra measured on samples extracted at low reactor temperatures showed the starting materials Fe(acac)3 diluted in benzyl alcohol undergoing slow paramagnetic relaxation, a sample extracted at a reactor temperature of 180 °C gave clear evidence for emerging iron oxide nanoparticles. A prolonged stay at 200 °C results in a complete transformation from Fe(acac)3 to maghemite nanoparticles.

Kraken, M.; Masthoff, I.-C.; Borchers, A.; Litterst, F. J.; Garnweitner, G.

2014-01-01

346

Antitumor effect of TRAIL on oral squamous cell carcinoma using magnetic nanoparticle-mediated gene expression.  

PubMed

We developed a new magnetic nanovector to improve the efficiency and targeting of transgene therapy for oral squamous cell carcinoma (OSCC). Positively charged polymer PEI-modified Fe(3)O(4) magnetic nanoparticles were tested as gene transfer vectors in the presence of a magnetic field. The Fe(3)O(4) nanoparticles were prepared by a co-precipitation method and had good dispersibility in water. These nanoparticles modified by PEI were combined with negatively charged pACTERT-EGFP via electrostatic interaction. The transfection efficiency of the magnetic nano-gene vector with the magnetic field was determined by a fluorescence-inverted microscope and flow cytometry. The results showed significant improvement compared with the control group (p < 0.05). The magnetic complexes also exhibited up to 6-times higher transfection efficiency compared with commonly used PEI or lipofectin. On the basis of these results, the antitumor effect with suicide gene therapy using pACTERT-TRAIL in vitro and vivo was evaluated. In vitro apoptosis was determined with the Annexin V-FITC Apoptosis Detection Kit. The results suggested that PEI-modified Fe(3)O(4) nanoparticles could mediate the killing of Tca83 cells. Furthermore, treatment with pACTERT-TRAIL delivered by magnetic nanoparticles showed a significant cytostatic effect through the induction of apoptosis in a xenograft model. This indicates that magnetic nano-gene vectors could improve the transgene efficiency for Tca83 cells and could exhibit antitumor functions with the plasmid pACTERT-TRAIL. This may be a new way to treat OSCC. PMID:24563116

Miao, Leiying; Liu, Chao; Ge, Jiuyu; Yang, Weidong; Liu, Jinzhong; Sun, Weibin; Yang, Bai; Zheng, Changyu; Sun, Hongchen; Hu, Qingang

2014-07-01

347

Grain size effect on site-disorder and magnetic properties of multiferroic GaFeO3 nanoparticles  

NASA Astrophysics Data System (ADS)

GaFeO3 (GFO) nanoparticles with different grain sizes (16-152 nm) have been synthesized by a modified Pechini method. The magnetic characterization indicates that with decreasing grain size, the ferrimagnetic transition temperature (TC) increases from 275 to 325 K. The magnetic hysteresis curves measured below TC exhibit two-phase-like magnetic behavior consisting of soft and hard magnetic phases. The results could be explained by the site-disorder of the cations in GFO. Furthermore, thermo-magnetic irreversibility and cusp in zero-field cooled magnetization are observed for all the GFO nanoparticles, which are attributed to the inherent magnetic anisotropy.

Han, T. C.; Chen, T. Y.; Lee, Y. C.

2013-12-01

348

Smart magnetic nanoparticle-aptamer probe for targeted imaging and treatment of hepatocellular carcinoma.  

PubMed

We report herein the development of a smart magnetic nanoparticle-aptamer probe, or theranostic nanoprobe, which can be used for targeted imaging and as a drug carrier for hepatocellular carcinoma treatment. The theranostic nanoprobe combines the delivery potential of a non-toxic cellulose derivative polymer, specific capability of cancer-specific molecule (DNA-based EpCAM aptamer) and the imaging capability of magnetic iron oxide nanoparticles. Our proof-of-concept design demonstrates efficient in vitro MR imaging of the cancer cells, and enhanced delivery of an anticancer drug into the cancer cells with comparable treatment efficacy. PMID:25089503

Pilapong, Chalermchai; Sitthichai, Sudarat; Thongtem, Somchai; Thongtem, Titipun

2014-10-01

349

Colloidal stability of magnetic nanoparticles in molten salts  

E-print Network

Molten salts are important heat transfer fluids used in nuclear, solar and other high temperature engineering systems. Dispersing nanoparticles in molten salts can enhance the heat transfer capabilities of the fluid. High ...

Somani, Vaibhav (Vaibhav Basantkumar)

2010-01-01

350

Role of nanoparticle valency in the nondestructive magnetic-relaxation-mediated detection and magnetic isolation of cells in complex media.  

PubMed

Nanoparticle-based diagnostics typically involve the conjugation of targeting ligands to the nanoparticle to create a sensitive and specific nanosensor that can bind and detect the presence of a target, such as a bacterium, cancer cell, protein, or DNA sequence. Studies that address the effect of multivalency on the binding and detection pattern of these nanosensors, particularly on magnetic relaxation nanosensors that sense the presence of a target in a dose-dependent manner by changes in the water relaxation times (DeltaT2), are scarce. Herein, we study the effect of multivalency on the detection profile of cancer cells and bacteria in complex media, such as blood and milk. In these studies, we conjugated folic acid at two different densities (low-folate and high-folate) on polyacrylic-acid-coated iron oxide nanoparticles and studied the interaction of these magnetic nanosensors with cancer cells expressing the folate receptor. Results showed that the multivalent high-folate magnetic relaxation nanosensor performed better than its low folate counterpart, achieving single cancer cell detection in blood samples within 15 min. Similar results were also observed when a high molecular weight anti-folate antibody (MW 150 kDa) was used instead of the low molecular weight folic acid ligand (MW 441.4 kDa), although better results in terms of sensitivity, dynamic range, and speed of detection were obtained when the folate ligand was used. Studies using bacteria in milk suspensions corroborated the results observed with cancer cells. Taken together, these studies demonstrate that nanoparticle multivalency plays a key role in the interaction of the nanoparticle with the cellular target and modulate the behavior and sensitivity of the assay. Furthermore, as detection with magnetic relaxation nanosensors is a nondestructive technique, magnetic isolation and further characterization of the cancer cells is possible. PMID:19681607

Kaittanis, Charalambos; Santra, Santimukul; Perez, J Manuel

2009-09-01

351

Exchange-coupled nanocomposite magnets by nanoparticle self-assembly  

Microsoft Academic Search

Exchange-spring magnets are nanocomposites that are composed of magnetically hard and soft phases that interact by magnetic exchange coupling. Such systems are promising for advanced permanent magnetic applications, as they have a large energy product-the combination of permanent magnet field and magnetization-compared to traditional, single-phase materials. Conventional techniques, including melt-spinning, mechanical milling and sputtering, have been explored to prepare exchange-spring

Hao Zeng; Jing Li; J. P. Liu; Zhong L. Wang; Shouheng Sun

2002-01-01

352

Structural and magnetic properties of Mn nanoparticles prepared by arc-discharge  

SciTech Connect

Mn nanoparticles are prepared by arc discharge technique. MnO, {alpha}-Mn, {beta}-Mn, and {gamma}-Mn are detected by X-ray diffraction, while the presence of Mn{sub 3}O{sub 4} and MnO{sub 2} is revealed by X-ray photoelectron spectroscopy. Transmission electron microscopy observations show that most of the Mn nanoparticles have irregular shapes, rough surfaces and a shell/core structure, with sizes ranging from several nanometers to 80 nm. The magnetic properties of the Mn nanoparticles are investigated between 2 and 350 K at magnetic fields up to 5 T. A magnetic transition occurring near 43 K is attributed to the formation of the ferrimagnetic Mn{sub 3}O{sub 4}. The coercivity of the Mn nanoparticles, arising mainly from Mn{sub 3}O{sub 4}, decreases linearly with increasing temperature below 40 K. Below the blocking temperature T{sub B} {approx} 34 K, the hysteresis loops exhibit large coercivity (up to 500 kA/m), owing to finite size effects, and irreversibility in the loops is found up to 4 T, and magnetization is not saturated up to 5 T. The relationship between structure and the magnetic properties are discussed.

Si, P.Z. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, International Centre for Materials Physics, Chinese Academy of Sciences, Shenyang 110016 (China) and Van der Waals-Zeeman Institute, University of Amsterdam, ValckenierstrAt 65, NL-1018 XE Amsterdam (Netherlands)]. E-mail: psi@science.uva.nl; Brueck, E. [Van der Waals-Zeeman Institute, University of Amsterdam, ValckenierstrAt 65, NL-1018 XE Amsterdam (Netherlands); Zhang, Z.D. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, International Centre for Materials Physics, Chinese Academy of Sciences, Shenyang 110016 (China); Tegus, O. [Van der Waals-Zeeman Institute, University of Amsterdam, ValckenierstrAt 65, NL-1018 XE Amsterdam (Netherlands); Zhang, W.S. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, International Centre for Materials Physics, Chinese Academy of Sciences, Shenyang 110016 (China); Buschow, K.H.J. [Van der Waals-Zeeman Institute, University of Amsterdam, ValckenierstrAt 65, NL-1018 XE Amsterdam (Netherlands); KlAsse, J.C.P. [Van der Waals-Zeeman Institute, University of Amsterdam, ValckenierstrAt 65, NL-1018 XE Amsterdam (Netherlands)

2005-01-04

353

PEG-Functionalized Magnetic Nanoparticles for Drug Delivery and Magnetic Resonance Imaging Applications  

PubMed Central

Purpose Polyethylene glycol (PEG) functionalized magnetic nanoparticles (MNPs) were tested as a drug carrier system, magnetic resonance imaging (MRI) agent, and ability to conjugate to an antibody. Methods An iron oxide core coated with oleic acid (OA) and then with OA-PEG forms a water dispersible MNP formulation. Hydrophobic doxorubicin partitions into the OA layer for sustained drug delivery. The T1 and T2 MRI contrast properties were determined in vitro and the circulation of the MNPs measured in mouse carotid arteries. An N-hydroxysuccinimide group (NHS) on the OA-PEG-80 was used to conjugate the amine functional group on antibodies for active targeting in the human MCF-7 breast cancer cell line. Results The optimized formulation had a mean hydrodynamic diameter of 184 nm with an 8 nm iron-oxide core. The MNPs enhance the T2 MRI contrast, and have a long circulation time in vivo with 30% relative concentration 50 min post-injection. Doxorubicin-loaded MNPs showed sustained drug release and dose-dependent antiproliferative effects in vitro; the drug effect was enhanced with transferrin antibody conjugated MNPs. Conclusion PEG functionalized MNPs could be developed as a targeted drug delivery system and MRI contrast agent. PMID:20845067

Yallapu, Murali Mohan; Foy, Susan P; Jain, Tapan K; Labhasetwar, Vinod

2010-01-01

354

The influence of surface functionalization on the enhanced internalization of magnetic nanoparticles in cancer cells  

NASA Astrophysics Data System (ADS)

The internalization and biocompatibility of iron oxide nanoparticles surface functionalized with four differently charged carbohydrates have been tested in the human cervical carcinoma cell line (HeLa). Neutral, positive, and negative iron oxide nanoparticles were obtained by coating with dextran, aminodextran, heparin, and dimercaptosuccinic acid, resulting in colloidal suspensions stable at pH 7 with similar aggregate size. No intracellular uptake was detected in cells incubated with neutral charged nanoparticles, while negative particles showed different behaviour depending on the nature of the coating. Thus, dimercaptosuccinic-coated nanoparticles showed low cellular uptake with non-toxic effects, while heparin-coated particles showed cellular uptake only at high nanoparticle concentrations and induced abnormal mitotic spindle configurations. Finally, cationic magnetic nanoparticles show excellent properties for possible in vivo biomedical applications such as cell tracking by magnetic resonance imaging (MRI) and cancer treatment by hyperthermia: (i) they enter into cells with high effectiveness, and are localized in endosomes; (ii) they can be easily detected inside cells by optical microscopy, (iii) they are retained for relatively long periods of time, and (iv) they do not induce any cytotoxicity.

Villanueva, Angeles; Cañete, Magdalena; Roca, Alejandro G; Calero, Macarena; Veintemillas-Verdaguer, Sabino; Serna, Carlos J; del Puerto Morales, María; Miranda, Rodolfo

2009-03-01

355

1H relaxation enhancement induced by nanoparticles in solutions: Influence of magnetic properties and diffusion  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles that induce nuclear relaxation are the most promising materials to enhance the sensitivity in Magnetic Resonance Imaging. In order to provide a comprehensive understanding of the magnetic field dependence of the relaxation enhancement in solutions, Nuclear Magnetic Resonance 1H spin-lattice relaxation for decalin and toluene solutions of various Fe2O3 nanoparticles was investigated. The relaxation experiments were performed in a frequency range of 10 kHz-20 MHz by applying Field Cycling method, and in the temperature range of 257-298 K, using nanoparticles differing in size and shape: spherical - 5 nm diameter, cubic - 6.5 nm diameter, and cubic - 9 nm diameter. The relaxation dispersion data were interpreted in terms of a theory of nuclear relaxation induced by magnetic crystals in solution. The approach was tested with respect to its applicability depending on the magnetic characteristics of the nanocrystals and the time-scale of translational diffusion of the solvent. The role of Curie relaxation and the contributions to the overall 1H spin-lattice relaxation associated with the electronic spin-lattice and spin-spin relaxation was thoroughly discussed. It was demonstrated that the approach leads to consistent results providing information on the magnetic (electronic) properties of the nanocrystals, i.e., effective electron spin and relaxation times. In addition, features of the 1H spin-lattice relaxation resulting from the electronic properties of the crystals and the solvent diffusion were explained.

Kruk, D.; Korpa?a, A.; Taheri, S. Mehdizadeh; Koz?owski, A.; Förster, S.; Rössler, E. A.

2014-05-01

356

Dual-responsive magnetic core-shell nanoparticles for nonviral gene delivery and cell separation.  

PubMed

We present the synthesis of dual-responsive (pH and temperature) magnetic core-shell nanoparticles utilizing the grafting-from approach. First, oleic acid stabilized superparamagnetic maghemite (?-Fe(2)O(3)) nanoparticles (NPs), prepared by thermal decomposition of iron pentacarbonyl, were surface-functionalized with ATRP initiating sites bearing a dopamine anchor group via ligand exchange. Subsequently, 2-(dimethylamino)ethyl methacrylate (DMAEMA) was polymerized from the surface by ATRP, yielding dual-responsive magnetic core-shell NPs (?-Fe(2)O(3)@PDMAEMA). The attachment of the dopamine anchor group on the nanoparticle's surface is shown to be reversible to a certain extent, resulting in a grafting density of 0.15 chains per nm(2) after purification. Nevertheless, the grafted NPs show excellent long-term stability in water over a wide pH range and exhibit a pH- and temperature-dependent reversible agglomeration, as revealed by turbidimetry. The efficiency of ?-Fe(2)O(3)@PDMAEMA hybrid nanoparticles as a potential transfection agent was explored under standard conditions in CHO-K1 cells. Remarkably, ?-Fe(2)O(3)@PDMAEMA led to a 2-fold increase in the transfection efficiency without increasing the cytotoxicity, as compared to polyethyleneimine (PEI), and yielded on average more than 50% transfected cells. Moreover, after transfection with the hybrid nanoparticles, the cells acquired magnetic properties that could be used for selective isolation of transfected cells. PMID:22296556

Majewski, Alexander P; Schallon, Anja; Jérôme, Valérie; Freitag, Ruth; Müller, Axel H E; Schmalz, Holger

2012-03-12

357

Surface-spin magnetism of antiferromagnetic NiO in nanoparticle and bulk morphology  

NASA Astrophysics Data System (ADS)

The surface-spin magnetism of the antiferromagnetic (AFM) material NiO in nanoparticle and bulk morphology was investigated by magnetic measurements (temperature-dependent zero-field-cooled (zfc) and field-cooled (fc) dc susceptibility, ac susceptibility and zfc and fc hysteresis loops). We addressed the question of whether the multisublattice ordering of the uncompensated surface spins and the exchange bias (EB) effect are only present in the nanoparticles, originating from their high surface-to-volume ratio or if these surface phenomena are generally present in the AFM materials regardless of their bulky or nanoparticle morphology, but the effect is just too small to be detected experimentally in the bulk due to a very small surface magnetization. Performing experiments on the NiO nanoparticles of different sizes and bulk NiO grains, we show that coercivity enhancement and hysteresis loop shift in the fc experiments, considered to be the key experimental manifestations of multisublattice ordering and the EB effect, are true nanoscale phenomena only present in the nanoparticles and absent in the bulk.

Jagodi?, M.; Jagli?i?, Z.; Jelen, A.; Lee, Jin Bae; Kim, Young-Min; Kim, Hae Jin; Dolinšek, J.

2009-05-01

358

Magnetic properties and microstructure of cobalt nanoparticles in a polymer film  

NASA Astrophysics Data System (ADS)

Superparamagnetic properties of self-aggregated cobalt nanoparticles in the perfluorinated sulfo-cation membrane (MF-4SK) prepared by ion-exchange method were investigated by transmission electron microscopy (TEM) and superconducting quantum interference device (SQUID) magnetometry at various temperatures. Our experimental results show that cobalt nanoparticles in MF-4SK exhibit superparamagnetic properties above the blocking temperature ( TB), which varies from ˜80 to ˜300 K depending on the cobalt concentration at 100 Oe applied field. The average particle radius of 3.8 nm inferred from Langevin function fit for the concentration of 7.8×10 19 cobalt atoms per 1 g of polymer film is in good agreement with TEM observation. This experimental evidence suggests that cobalt nanoparticles in the polymer film obey a single-domain theory. The results are discussed in the light of current theory for the superparamagnetic behavior of magnetic nanoparticles.

Park, I.-W.; Yoon, M.; Kim, Y. M.; Kim, Y.; Yoon, H.; Song, H. J.; Volkov, V.; Avilov, A.; Park, Y. J.

2003-05-01

359

Synthesis and characterization of iron platinum magnetic nanoparticles with controlled morphology and size  

NASA Astrophysics Data System (ADS)

We report the synthesis and characterization of monodispersed iron-platinum nanoparticles by the thermal decomposition of organometallic compounds. First, platinum (Pt) seeds were synthesized at 100C, followed by the addition of iron pentacarbonyl via injection method in the presence of oleic acid and oleylamine surfactants. An immediate injection after the decomposition of Pt acetylacetonate made alloy nanoparticles of Pt nanoparticles, whereas its injection after a prolonged period of time formed mixed particles of iron oxide and Pt. Particle shape was tuned from spherical to cubic by varying molar ratios of oleic acid to oleylamine during the reaction. The particles' size was controlled by varying the injection temperature of the iron precursor. XRD was used to confirm the crystallographic phases of the samples. Particle size and shape were investigated using TEM. Magnetic properties indicated that as-synthesized FePt nanoparticles are superparamagnetic with a blocking temperature of 64 K for 7 nm and shifted to 29 K for 3 nm.

Combs, Trinidy; Khurshid, Hafsa; Srikanth, Hariharan

2013-03-01

360

The effects of surface spin on magnetic properties of weak magnetic ZnLa0.02Fe1.98O4 nanoparticles  

PubMed Central

In order to prominently investigate the effects of the surface spin on the magnetic properties, the weak magnetic ZnLa0.02Fe1.98O4 nanoparticles were chosen as studying objects which benefit to reduce as possibly the effects of interparticle dipolar interaction and crystalline anisotropy energies. By annealing the undiluted and diluted ZnLa0.02Fe1.98O4 nanoparticles at different temperatures, we observed the rich variations of magnetic ordering states (superparamagnetism, weak ferromagnetism, and paramagnetism). The magnetic properties can be well understood by considering the effects of the surface spin of the magnetic nanoparticles. Our results indicate that in the nano-sized magnets with weak magnetism, the surface spin plays a crucial rule in the magnetic properties. PMID:25294976

2014-01-01

361

Effect of magnetic dipolar interactions on nanoparticle heating efficiency: Implications for cancer hyperthermia  

PubMed Central

Nanostructured magnetic systems have many applications, including potential use in cancer therapy deriving from their ability to heat in alternating magnetic fields. In this work we explore the influence of particle chain formation on the normalized heating properties, or specific loss power (SLP) of both low- (spherical) and high- (parallelepiped) anisotropy ferrite-based magnetic fluids. Analysis of ferromagnetic resonance (FMR) data shows that high particle concentrations correlate with increasing chain length producing decreasing SLP. Monte Carlo simulations corroborate the FMR results. We propose a theoretical model describing dipole interactions valid for the linear response regime to explain the observed trends. This model predicts optimum particle sizes for hyperthermia to about 30% smaller than those previously predicted, depending on the nanoparticle parameters and chain size. Also, optimum chain lengths depended on nanoparticle surface-to-surface distance. Our results might have important implications to cancer treatment and could motivate new strategies to optimize magnetic hyperthermia. PMID:24096272

Branquinho, Luis C.; Carriao, Marcus S.; Costa, Anderson S.; Zufelato, Nicholas; Sousa, Marcelo H.; Miotto, Ronei; Ivkov, Robert; Bakuzis, Andris F.

2013-01-01

362

The effect of Neel relaxation on the properties of the third harmonic signal of magnetic nanoparticles for use in narrow-band magnetic nanoparticle imaging  

NASA Astrophysics Data System (ADS)

We study the third harmonic signal of magnetic nanoparticles (MNPs) for use in narrow-band magnetic nanoparticle imaging. We measured the properties of the third harmonic signal, such as frequency and magnetic field dependencies, when the behavior of MNPs was dominated by Neel relaxation. It was shown that the third harmonic signal had both real and imaginary parts, although only the real part is expected from the conventional Langevin function. The real and imaginary parts exhibited different dependences on the frequency and magnetic field. The dynamic behavior of MNPs was analyzed by taking into account the Neel relaxation of MNPs. It was shown that the imaginary part was generated due to Neel relaxation. We obtain an analytical expression for the third harmonic signal, in which distributions of magnetic moment and anisotropic energy of MNPs in the sample were also considered. We show that the analytical results quantitatively explain the experimental results. Our results indicate that the properties of the third harmonic signal of immobilized MNPs are significantly affected by Neel relaxation.

Enpuku, Keiji; Bai, Shi; Hirokawa, Aiki; Tanabe, Kazuhiro; Sasayama, Teruyoshi; Yoshida, Takashi

2014-10-01

363

Controlled differentiation of human bone marrow stromal cells using magnetic nanoparticle technology.  

PubMed

Targeting and differentiating stem cells at sites of injury and repair is an exciting and promising area for disease treatment and reparative medicine. We have investigated remote magnetic field activation of magnetic nanoparticle-tagged mechanosensitive receptors on the cell membrane of human bone marrow stromal cells (HBMSCs) for use in osteoprogenitor cell delivery systems and activation of differentiation in vitro and in vivo toward an osteochondral lineage. HBMSC-labeled with magnetic beads coated with antibodies or peptides to the transmembrane ion channel stretch activated potassium channel (TREK-1) or arginine–glycine–aspartic acid were cultured in monolayer or encapsulated into polysaccharide alginate/chitosan microcapsules. Upregulation in gene expression was measured in magnetic particle-labeled HBMSCs in response to TREK-1 activation over a short period (7 days) with an increase in mRNA levels of Sox9, core binding factor alpha1 (Cbfa1), and osteopontin. Magnetic particle-labeled HBMSCs encapsulated into alginate chitosan capsules were exposed to magnetic forces both in vitro and in vivo intermittently for 21 days. After 21 days the encapsulated, magnetic particle-labeled HBMSCs in vivo were viable as evidenced by extensive cell tracker green fluorescence. The mechanical stimulation of HBMSCs labeled with TREK-1 magnetic nanoparticle receptors enhanced expression of type-1 collagen in vitro with increases in proteoglycan matrix, core binding factor alpha1 (Cbfa1) and collagen synthesis, and extracellular matrix production and elevated the expression of type-1 and type-2 collagen in vivo. Additionally, the magnetically remote stimulation of HBMSCs labeled with magnetic nanoparticle arginine–glycine–aspartic acid considerably enhanced proteoglycan and collagen synthesis and extracellular matrix production and elevated the expression of type-1 and type-2 collagen in vivo and in vitro. Osteogenic mechanosensitive receptor manipulation by magnetic nanotechnology can induce the differentiation of osteoprogenitor cell populations toward an osteogenic lineage. These cell manipulation strategies offer tremendous therapeutic opportunities in soft and hard tissue repair. PMID:20504072

Kanczler, Janos M; Sura, Harpul S; Magnay, Julia; Green, David; Oreffo, Richard O C; Dobson, Jon P; El Haj, Alicia J

2010-10-01

364

Magnetic nanoparticle-mediated massively-parallel mechanical modulation of single-cell behavior  

PubMed Central

We report a technique for generating controllable, time-varying and localizable forces on arrays of cells in a massively parallel fashion. To achieve this, we grow magnetic nanoparticle-dosed cells in defined patterns on micro-magnetic substrates. By manipulating and coalescing nanoparticles within cells, we apply localized nanoparticle-mediated forces approaching cellular yield tensions on the cortex of HeLa cells. We observed highly coordinated responses in cellular behavior, including the p21-activated kinase (PAK)-dependent generation of active, leading-edge type filopodia, and biasing of the metaphase plate during mitosis. The large sample size and rapid sample generation inherent to this approach allow the analysis of cells at an unprecedented rate; a single experiment can potentially stimulate tens of thousands of cells for high statistical accuracy in measurements. This technique shows promise as a tool for both cell analysis and control. PMID:23064517

Tseng, Peter; Judy, Jack W.; Di Carlo, Dino

2012-01-01

365

Design and fabrication of magnetic nanoparticles for targeted drug delivery and imaging  

PubMed Central

Magnetic nanoparticles (MNPs) represent a class of non-invasive imaging agents that have been developed for magnetic resonance (MR) imaging. These MNPs have traditionally been used for disease imaging via passive targeting, but recent advances have opened the door to cellular-specific targeting, drug delivery, and multi-modal imaging by these nanoparticles. As more elaborate MNPs are envisioned, adherence to proper design criteria (e.g. size, coating, molecular functionalization) becomes even more essential. This review summarizes the design parameters that affect MNP performance in vivo, including the physicochemical properties and nanoparticle surface modifications, such as MNP coating and targeting ligand functionalizations that can enhance MNP management of biological barriers. A careful review of the chemistries used to modify the surfaces of MNPs is also given, with attention paid to optimizing the activity of bound ligands while maintaining favorable physicochemical properties. PMID:19909778

Veiseh, Omid; Gunn, Jonathan; Zhang, Miqin

2009-01-01

366

Structural and magnetic characterization of Co-Cu nanoparticles prepared by arc-discharge  

NASA Astrophysics Data System (ADS)

The structure and magnetic properties of the nanoparticles of immiscible system Co{20}Cu{80} prepared by means of arc-discharge, have been studied in detail. The diameters of the particles are about 20 ˜ 30 nm and a core/shell structure forms. The cores are Co-Cu solutions, which show some small Co precipitates, encapsulated with a shell of cupper oxide or cobalt oxide as observed by means of high-resolution transmission electron microscope (HRTEM) and energy dispersive X-ray (EDS). The loop shift in the hysteresis loop indicates the existence of the exchange bias between ferromagnetic and antiferromagnetic components at low temperatures. A block temperature about 180 K has been observed for as-deposited nanoparticles. For the annealed nanoparticles, the thermal magnetization at low temperatures is satisfied with Bloch's law.

You, Cai-Yin; Yang, Z. Q.; Xiao, Q. F.; Škorvánek, I.; Ková?, J.; Li, Z. J.; Liu, W.; Zhang, Z. D.

2004-10-01

367

Effect of spatial confinement on magnetic hyperthermia via dipolar interactions in Fe?O? nanoparticles for biomedical applications.  

PubMed

In this work, the effect of nanoparticle confinement on the magnetic relaxation of iron oxide (Fe3O4) nanoparticles (NP) was investigated by measuring the hyperthermia heating behavior in high frequency alternating magnetic field. Three different Fe3O4 nanoparticle systems having distinct nanoparticle configurations were studied in terms of magnetic hyperthermia heating rate and DC magnetization. All magnetic nanoparticle (MNP) systems were constructed using equivalent ~10nm diameter NP that were structured differently in terms of configuration, physical confinement, and interparticle spacing. The spatial confinement was achieved by embedding the Fe3O4 nanoparticles in the matrices of the polystyrene spheres of 100 nm, while the unconfined was the free Fe3O4 nanoparticles well-dispersed in the liquid via PAA surface coating. Assuming the identical core MNPs in each system, the heating behavior was analyzed in terms of particle freedom (or confinement), interparticle spacing, and magnetic coupling (or dipole-dipole interaction). DC magnetization data were correlated to the heating behavior with different material properties. Analysis of DC magnetization measurements showed deviation from classical Langevin behavior near saturation due to dipole interaction modification of the MNPs resulting in a high magnetic anisotropy. It was found that the Specific Absorption Rate (SAR) of the unconfined nanoparticle systems were significantly higher than those of confined (the MNPs embedded in the polystyrene matrix). This increase of SAR was found to be attributable to high Néel relaxation rate and hysteresis loss of the unconfined MNPs. It was also found that the dipole-dipole interactions can significantly reduce the global magnetic response of the MNPs and thereby decrease the SAR of the nanoparticle systems. PMID:25063092

Sadat, M E; Patel, Ronak; Sookoor, Jason; Bud'ko, Sergey L; Ewing, Rodney C; Zhang, Jiaming; Xu, Hong; Wang, Yilong; Pauletti, Giovanni M; Mast, David B; Shi, Donglu

2014-09-01

368

Supported ruthenium-carbene catalyst on ionic magnetic nanoparticles for olefin metathesis.  

PubMed

The Grubbs-Hoveyda ruthenium-carbene complex has been covalently immobilized on ionic magnetic nanoparticles utilizing an imidazolium salt linker. The supported catalyst exhibited excellent catalytic activity for ring-closing metathesis (RCM) and cross-metathesis (CM) in the presence of less than 1 mol % of ruthenium. The catalysts can easily be recovered magnetically and reused up to seven times with minimal leaching of ruthenium species. PMID:25215600

Chen, Shu-Wei; Zhang, Zhi-Cheng; Ma, Miaofeng; Zhong, Chong-Min; Lee, Sang-gi

2014-10-01

369

nanoparticles  

NASA Astrophysics Data System (ADS)

In this work, we present the role of vanadium ions (V+5 and V+3), oxygen vacancies (VO), and interstitial zinc (Zni) to the contribution of specific magnetization for a mixture of ZnO-V2O5 nanoparticles (NPs). Samples were obtained by mechanical milling of dry powders and ethanol-assisted milling for 1 h with a fixed atomic ratio V/Zn?=?5% at. For comparison, pure ZnO samples were also prepared. All samples exhibit a room temperature magnetization ranging from 1.18?×?10-3 to 3.5?×?10-3 emu/gr. Pure ZnO powders (1.34?×?10-3 emu/gr) milled with ethanol exhibit slight increase in magnetization attributed to formation of Zni, while dry milled ZnO powders exhibit a decrease of magnetization due to a reduction of VO concentration. For the ZnO-V2O5 system, dry milled and thermally treated samples under reducing atmosphere exhibit a large paramagnetic component associated to the formation of V2O3 and secondary phases containing V+3 ions; at the same time, an increase of VO is observed with an abrupt fall of magnetization to ??~?0.7?×?10-3 emu/gr due to segregation of V oxides and formation of secondary phases. As mechanical milling is an aggressive synthesis method, high disorder is induced at the surface of the ZnO NPs, including VO and Zni depending on the chemical environment. Thermal treatment restores partially structural order at the surface of the NPs, thus reducing the amount of Zni at the same time that V2O5 NPs segregate reducing the direct contact with the surface of ZnO NPs. Additional samples were milled for longer time up to 24 h to study the effect of milling on the magnetization; 1-h milled samples have the highest magnetizations. Structural characterization was carried out using X-ray diffraction and transmission electron microscopy. Identification of VO and Zni was carried out with Raman spectra, and energy-dispersive X-ray spectroscopy was used to verify that V did not diffuse into ZnO NPs as well to quantify O/Zn ratios.

Olive-Méndez, Sion F.; Santillán-Rodríguez, Carlos R.; González-Valenzuela, Ricardo A.; Espinosa-Magaña, Francisco; Matutes-Aquino, José A.

2014-04-01

370

Multiplexed immunoassays for proteins using magnetic luminescent nanoparticles for internal calibration  

E-print Network

Multiplexed immunoassays for proteins using magnetic luminescent nanoparticles for internal with the capture anti- bodies. Secondary antibodies labeled with conventional organic dyes (Alexa Fluor) are used for three model pro- teins (human, rabbit, and mouse IgGs). The method uses a standard bench plate reader

Hammock, Bruce D.

371

Magnetorelaxometry of magnetic nanoparticles with fluxgate magnetometers for the analysis of biological targets  

Microsoft Academic Search

A magnetorelaxometry system based on sensitive fluxgate magnetometers for the analysis of the relaxation behavior of magnetic nanoparticles is presented. The system is tested with a dilution series of magnetite. The results are directly compared with data obtained with a SQUID magnetorelaxometry system measured on the same samples. Advantages of using fluxgates rather than SQUIDs for magnetorelaxometry are discussed.

Frank Ludwig; Erik Heim; Sascha Mäuselein; Dietmar Eberbeck; Meinhard Schilling

2005-01-01

372

A Disposable and Magnetic NanoParticles Composite Membrane Modified Amperometric Immunosensor for Determination of Chloramphenicol  

Microsoft Academic Search

A disposable and magnetic nanoparticles composite membrane modified screen printed carbon electrodes (SPCEs) for rapid determination of chloramphenicol (CAP) in milk has been fabricated and characterized by scanning electron microscope (SEM) and voltammetry. The reagentless amperometric immunosensor was prepared by entrapping ferrocene (Fc) and carbon nanotubes (CNTs) into Nafion (Nf) to form a composite Nf\\/CNTs\\/Fc membrane, which yield an interface

Xin Yang; Ning Gan; Nai-xing Luo; Dong-hua Xie; Wei-gang Wen

2009-01-01

373

Modeling of the magnetic behavior of -Fe2O3 nanoparticles mineralized in ferritin  

E-print Network

Modeling of the magnetic behavior of -Fe2O3 nanoparticles mineralized in ferritin Damon Resnick,a) Keith Gilmore, and Y. U. Idzerda Department of Physics and The Center for Bioinspired Nanomaterials American Institute of Physics. DOI: 10.1063/1.1669211 I. INTRODUCTION The synthesis of monodisperse

Idzerda, Yves

374

Functionalization-induced improvement in magnetic properties of Fe3O4 nanoparticles for biomedical applications  

E-print Network

, and to make them suitable for aqueous environments, dopamine ligand exchange was carried out on the particles MS, and blocking temperature TB of the particles was found after dopamine functionalization, even are consistent with an increase in the magnetic size of the nanoparticle core induced by the dopamine ligand

Sridhar, Srinivas

375

Catalytically active bovine serum amine oxidase bound to fluorescent and magnetically drivable nanoparticles  

PubMed Central

Novel superparamagnetic surface-active maghemite nanoparticles (SAMNs) characterized by a diameter of 10 ± 2 nm were modified with bovine serum amine oxidase, which used rhodamine B isothiocyanate (RITC) adduct as a fluorescent spacer-arm. A fluorescent and magnetically drivable adduct comprised of bovine serum copper-containing amine oxidase (SAMN–RITC–BSAO) that immobilized on the surface of specifically functionalized magnetic nanoparticles was developed. The multifunctional nanomaterial was characterized using transmission electron microscopy, infrared spectroscopy, mass spectrometry, and activity measurements. The results of this study demonstrated that bare magnetic nanoparticles form stable colloidal suspensions in aqueous solutions. The maximum binding capacity of bovine serum amine oxidase was approximately 6.4 mg g?1 nanoparticles. The immobilization procedure reduced the catalytic activity of the native enzyme to 30% ± 10% and the Michaelis constant was increased by a factor of 2. We suggest that the SAMN–RITC–BSAO complex, characterized by a specific activity of 0.81 IU g?1, could be used in the presence of polyamines to create a fluorescent magnetically drivable H2O2 and aldehydes-producing system. Selective tumor cell destruction is suggested as a potential future application of this system. PMID:22619559

Sinigaglia, Giulietta; Magro, Massimiliano; Miotto, Giovanni; Cardillo, Sara; Agostinelli, Enzo; Zboril, Radek; Bidollari, Eris; Vianello, Fabio

2012-01-01

376

Structural, magnetic, dielectric and optical properties of nickel ferrite nanoparticles synthesized by co-precipitation method  

NASA Astrophysics Data System (ADS)

Nickel ferrite nanoparticles were synthesized by wet chemical co-precipitation method and the corresponding temperature dependent structural, magnetic and optical properties of these nanoparticles have been investigated. X-ray diffraction patterns show the single phase cubic spinal crystal structure belonging to the space group Fd3m. The average crystallite size varies in the range 8-20 nm with varying sintering temperature. Raman spectroscopy exhibits a doublet-like peak behaviour which indicates the presence of mixed spinel structure. The saturation magnetization, coercivity and remanence increase with increasing sintering temperature from 250 to 550 °C. The non-saturation and low values of magnetization at high fields indicate the strong surface effects to magnetization in NiFe2O4 nanoparticles. The g-value calculated from electron spin resonance spectrum indicates the transfer of divalent metallic ion from octahedral to tetrahedral site (i.e. mixed spinel structure). The dielectric permittivity, loss tangent and ac conductivity measurements show strong temperature dependence at all frequencies. The observed ac conductivity response suggests that the conduction in ferrite nanoparticles is due to feeble polaron hopping between Fe3+/Fe2+ ions. Room temperature UV-vis diffuse spectra indicate that NiFe2O4 is an indirect band gap material with band gap ranges from 1.27 to 1.47 eV with varying sintering temperature. The photoluminescence study clearly indicates that the Ni2+ ions occupy both octahedral and tetrahedral sites confirming mixed spinel structure.

Joshi, Seema; Kumar, Manoj; Chhoker, Sandeep; Srivastava, Geetika; Jewariya, Mukesh; Singh, V. N.

2014-11-01

377

Biomarkers identification and detection based on GMR sensor and sub 13 nm magnetic nanoparticles  

Microsoft Academic Search

In this paper, we present a ultra high sensitive (Zeptomole, 10-21) technique to enable the detection of any potential low abundance biomarkers. We demonstrated for the first time the detection of sub 13 nm high-moment magnetic nanoparticle and the implementation of a novel magnetoresistive (GMR) biosensor concept with higher sensitivity and 10 times lower external field in real biomarker sensing

Yuanpeng Li; Ying Jing; Xiaofeng Yao; Balasubramanian Srinivasan; Yunhao Xu; Chengguo Xing; Jian-Ping Wang

2009-01-01

378

Magnetic nanoparticles for ultrafast mechanical control of inner ear hair cells.  

PubMed

We introduce cubic magnetic nanoparticles as an effective tool for precise and ultrafast control of mechanosensitive cells. The temporal resolution of our system is ?1000 times faster than previously used magnetic switches and is comparable to the current state-of-the-art optogenetic tools. The use of a magnetism-gated switch reported here can address the key challenges of studying mechanotransduction in biological systems. The cube-shaped magnetic nanoparticles are designed to bind to components of cellular membranes and can be controlled with an electromagnet to exert pico-Newtons of mechanical force on the cells. The cubic nanoparticles can thus be used for noncontact mechanical control of the position of the stereocilia of an inner ear hair cell, yielding displacements of tens of nanometers, with sub-millisecond temporal resolution. We also prove that such mechanical stimulus leads to the influx of ions into the hair cell. Our study demonstrates that a magnetic switch can yield ultrafast temporal resolution, and has capabilities for remote manipulation and biological specificity, and that such magnetic system can be used for the study of mechanotransduction processes of a wide range of sensory systems. PMID:25004005

Lee, Jae-Hyun; Kim, Ji-wook; Levy, Michael; Kao, Albert; Noh, Seung-Hyun; Bozovic, Dolores; Cheon, Jinwoo

2014-07-22

379

Magnetic properties of ?-Fe2O3 nanoparticles incorporated in a polystyrene resin matrix  

NASA Astrophysics Data System (ADS)

?-Fe2O3 magnetic nanoparticles ranging in average diameter from 3to10nm were synthesized into a polystyrene resin matrix by an ion-exchange method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Mössbauer spectroscopy, and SQUID magnetometry. The average particle size as determined from XRD and TEM was found to be strongly dependent upon the initial Fe valence state of the starting chloride salt(s) and on the number of steps that the salt introduction and ion-exchange process were repeated. Regardless of the initial Fe valence state and processing conditions, Mössbauer spectroscopy confirmed that the Fe in the resulting nanoparticles existed only as Fe(III) ions and that ?-Fe2O3 was the only phase present. The values of the saturation magnetization at 5K were found to be dependent upon the processing conditions and ranged from 203to333emu/cm3 , which are significantly smaller than the bulk value (408emu/cm3) for ?-Fe2O3 . As expected, the nanoparticles exhibited superparamagnetic behavior with the magnetic moments becoming frozen with decreasing temperature as evidenced by the appearance of a six-line splitting in the Mössbauer spectra, a bifurcation in the zero-field-cooled (ZFC) and field-cooled (FC) magnetizations, and an opening in the MV -vs- H hysteresis curves. The values of magnetic anisotropy constant (1.2-2.1×106ergs/cm3) determined from the differences between the ZFC and FC magnetizations were found to be higher than the bulk value (1.1×105ergs/cm3) for ?-Fe2O3 , and are probably due to surface effects. Likewise, the nanoparticle size distributions as deduced from the blocking temperature distribution function f(TB) based on fits to the difference in the ZFC and FC magnetization curves as well as from fits of the MV -vs- H curves in the superparamagnetic regime with a Langevin function indicate fairly broad distributions of particle sizes with the particle sizes being comparable to those deduced from XRD and TEM measurements. The smaller saturated magnetization values found for these nanoparticles combined with the non-zero slope of the high-field magnetization data suggests that these nanoparticles have a non-negligible surface layer of noncollinear spins surrounding a ferrimagnetically ordered ?-Fe2O3 core.

Vaishnava, P. P.; Senaratne, U.; Buc, E. C.; Naik, R.; Naik, V. M.; Tsoi, G. M.; Wenger, L. E.

2007-07-01

380

A quantitative design and analysis of magnetic nanoparticle heating systems  

E-print Network

Magnetic particles under the influence of an alternating magnetic field act as localized heating sources due to various loss mechanisms. This effect has been extensively investigated in hypothermia studies over the past ...

Khushrushahi, Shahriar Rohinton

2006-01-01

381

Multifunctional magnetic plasmonic nanoparticles for applications of magnetic/photo-thermal hyperthermia and surface enhanced Raman spectroscopy  

NASA Astrophysics Data System (ADS)

We prepared magnetic plasmonic nanocomposites, multicore MnFe2O4@SiO2@Ag magnetic nanoparticles (MFA-MNPs). Their magnetic and plasmonic properties were investigated for the applications of hyperthermia and chemical detection. The experiments showed that such nanocomposites could generate heat under the AC magnetic field mainly by the Néel relaxation and are suitable as thermal seeds in magnetic hyperthermia. Moreover, these nanocomposites also possess strong photo-thermal property under near infrared laser light by their properties of surface plasmonic resonance. The measurement of surface enhanced Raman spectroscopy (SERS) spectra exhibited that MFA-MNPs had high sensitivity to rhodamine 6G molecules at concentration of 0.5 ppb.

Lai-Jie, Jr.; Lai, Wan-Ru; Chen, Chuh-Yean; Chen, Shih-Wei; Chiang, Chen-Li

2013-04-01

382

Zirconium arsenate-modified magnetic nanoparticles: preparation, characterization and application to the enrichment of phosphopeptides.  

PubMed

Phosphorylation, one of the most important post-translational modifications of protein, plays a crucial role in a large number of biological processes. Large-scale identification of protein phosphorylation by mass spectrometry is still a challenging task because of the low abundance of phosphopeptides and sub-stoichiometry of phosphorylation. In this work, a novel strategy based on the specific affinity of zirconium arsenate to the phosphate group has been developed for the effective enrichment of phosphopeptides. Zirconium arsenate-modified magnetic nanoparticles (ZrAs-Fe(3)O(4)@SiO(2)) were prepared by covalent immobilization of zirconium arsenate on Fe(3)O(4)@SiO(2) magnetic nanoparticles under mild conditions, and characterized by transmission electron microscope (TEM), Fourier transform infrared (FT-IR) spectroscopy, energy dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometer (VSM). The prepared ZrAs-Fe(3)O(4)@SiO(2) was applied for the selective enrichment of phosphopeptides from the digestion mixture of phosphoproteins and bovine serum albumin (BSA). Our results demonstrated that the ZrAs-Fe(3)O(4)@SiO(2) magnetic nanoparticles possess higher selectivity for phosphopeptides and better capture capability towards multiply-phosphorylated peptides than commercial zirconium dioxide (ZrO(2)), which has been widely employed for the enrichment of phosphopeptides. In addition, endogenous phosphopeptides from human serum can be effectively captured by ZrAs-Fe(3)O(4)@SiO(2) magnetic nanoparticles. It is the first report, to the best of our knowledge, in which the zirconium arsenate-modified magnetic nanoparticles were successfully applied to the enrichment of phosphopeptides, which offers the potential application of this new material in phosphoproteomics study. PMID:22182930

Li, Xiao-Shui; Xu, Li-Dan; Zhu, Gang-Tian; Yuan, Bi-Feng; Feng, Yu-Qi

2012-02-21

383

Managing magnetic nanoparticle aggregation and cellular uptake: a precondition for efficient stem-cell differentiation and MRI tracking.  

PubMed

The labeling of stem cells with iron oxide nanoparticles is increasingly used to enable MRI cell tracking and magnetic cell manipulation, stimulating the fields of tissue engineering and cell therapy. However, the impact of magnetic labeling on stem-cell differentiation is still controversial. One compromising factor for successful differentiation may arise from early interactions of nanoparticles with cells during the labeling procedure. It is hypothesized that the lack of control over nanoparticle colloidal stability in biological media may lead to undesirable nanoparticle localization, overestimation of cellular uptake, misleading MRI cell tracking, and further impairment of differentiation. Herein a method is described for labeling mesenchymal stem cells (MSC), in which the physical state of citrate-coated nanoparticles (dispersed versus aggregated) can be kinetically tuned through electrostatic and magnetic triggers, as monitored by diffusion light scattering in the extracellular medium and by optical and electronic microscopy in cells. A set of statistical cell-by-cell measurements (flow cytometry, single-cell magnetophoresis, and high-resolution MRI cellular detection) is used to independently quantify the nanoparticle cell uptake and the effects of nanoparticle aggregation. Such aggregation confounds MRI cell detection as well as global iron quantification and has adverse effects on chondrogenetic differentiation. Magnetic labeling conditions with perfectly stable nanoparticles-suitable for obtaining