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1

Mass Spectrometric Detection of Neuropeptides Using Affinity-Enhanced Microdialysis with Antibody-Coated Magnetic Nanoparticles  

PubMed Central

Microdialysis (MD) is a useful sampling tool for many applications due to its ability to permit sampling from an animal concurrent with normal activity. MD is of particular importance in the field of neuroscience, in which it is used to sample neurotransmitters (NTs) while the animal is behaving in order to correlate dynamic changes in NTs with behavior. One important class of signaling molecules, the neuropeptides (NPs), however, presented significant challenges when studied with MD, due to the low relative recovery (RR) of NPs by this technique. Affinity-enhanced microdialysis (AE-MD) has previously been used to improve recovery of NPs and similar molecules. For AE-MD, an affinity agent (AA), such as an antibody-coated particle or free antibody, is added to the liquid perfusing the MD probe. This AA provides an additional mass transport driving force for analyte to pass through the dialysis membrane, and thus increases the RR. In this work, a variety of AAs have been investigated for AE-MD of NPs in vitro and in vivo, including particles with C18 surface functionality and antibody-coated particles. Antibody-coated magnetic nanoparticles (AbMnP) provided the best RR enhancement in vitro, with statistically significant (p<0.05) enhancements for 4 out of 6 NP standards tested, and RR increases up to 41-fold. These particles were then used for in vivo MD in the Jonah crab, Cancer borealis, during a feeding study, with mass spectrometric (MS) detection. 31 NPs were detected in a 30 min collection sample, compared to 17 when no AA was used. The use of AbMnP also increased the temporal resolution from 4–18 hrs in previous studies to just 30 min in this study. The levels of NPs detected were also sufficient for reliable quantitation with the MS system in use, permitting quantitative analysis of the concentration changes for 7 identified NPs on a 30 min time course during feeding. PMID:23249250

Schmerberg, Claire M.; Li, Lingjun

2012-01-01

2

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

3

Tensile Force-Dependent Neurite Elicitation via Anti-?1 Integrin Antibody-Coated Magnetic Beads  

PubMed Central

Previous work using glass microneedles to apply calibrated, localized force to neurons showed that tensile force is a sufficient signal for neurite initiation and elongation. However, previous studies did not examine the kinetics or probability of neurite initiation as a function of force or the rate of force application. Here we report the use of a new technique—magnetic bead force application—to systematically investigate the role of force in these phenomena with better ease of use and control over force than glass microneedles. Force-induced neurite initiation from embryonic chick forebrain neurons appeared to be a first-order random process whose rate increased with increasing force, and required the presence of peripheral microtubules. In addition, the probability of initiation was more than twofold lower for neurons exposed to rapid initial force ramps (450 pN/s) than for neurons exposed to slower ramps (1.5 and 11 pN/s). We observed a low force threshold for elongation (15–100 pN), which was not previously detected in chick forebrain neurites elongated by glass microneedles. Finally, neurites subjected to constant force elongated at variable instantaneous rates, and switched abruptly between elongation and retraction, similar to spontaneous, growth-cone-mediated outgrowth and microtubule dynamic instability. PMID:12829516

Fass, Joseph N.; Odde, David J.

2003-01-01

4

Single domain antibody coated gold nanoparticles as enhancer for Clostridium difficile toxin detection by electrochemical impedance immunosensors.  

PubMed

This work presents a sandwich-type electrochemical impedance immunosensor for detecting Clostridium difficile toxin A (TcdA) and toxin B (TcdB). Single domain antibody conjugated gold nanoparticles were applied to amplify the detection signal. Gold nanoparticles (Au NPs) were characterized by transmission electron microscopy and UV–vis spectra. The electron transfer resistance (Ret) of the working electrode surface was used as a parameter in the measurement of the biosensor. With the increase of the concentration of toxins from 1 pg/mL to 100 pg/mL, a linear relationship was observed between the relative electron transfer resistance and toxin concentration. In addition, the detection signal was enhanced due to the amplification effect. The limit of detection for TcdA and TcdB was found to be 0.61 pg/mL and 0.60 pg/mL respectively at a signal-to-noise ratio of 3 (S/N = 3). This method is simple, fast and ultrasensitive, thus possesses a great potential for clinical applications in the future. PMID:25460611

Zhu, Zanzan; Shi, Lianfa; Feng, Hanping; Zhou, H Susan

2015-02-01

5

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

6

Functional Magnetic Nanoparticles  

NASA Astrophysics Data System (ADS)

Nanoparticle system research and characterization is the focal point of this research and dissertation. In the research presented here, magnetite, cobalt, and ferrite nanoparticle systems have been explored in regard to their magnetocaloric effect (MCE) properties, as well as for use in polymer composites. Both areas of study have potential applications across a wide variety of interdisciplinary fields. Magnetite nanoparticles have been successfully dispersed in a polymer. The surface chemistry of the magnetic nanoparticle proves critical to obtaining a homogenous and well separated high density dispersion in PMMA. Theoretical studies found in the literature have indicated that surface interface energy is a critical component in dispersion. Oleic acid is used to alter the surface of magnetite nanoparticles and successfully achieve good dispersion in a PMMA thin film. Polypyrrole is then coated onto the PMMA composite layer. The bilayer is characterized using cross-sectional TEM, cross-sectional SEM, magnetic characterization, and low frequency conductivity. The results show that the superparmagnetic properties of the as synthesized particles are maintained in the composite. With further study of the properties of these nanoparticles for real and functional uses, MCE is studied on a variety of magnetic nanoparticle systems. Magnetite, manganese zinc ferrite, and cobalt ferrite systems show significant broadening of the MCE and the ability to tune the peak temperature of MCE by varying the size of the nanoparticles. Four distinct systems are studied including cobalt, cobalt core silver shell nanoparticles, nickel ferrite, and ball milled zinc ferrite. The results demonstrate the importance of surface characteristics on MCE. Surface spin disorder appears to have a large influence on the low temperature magnetic and magnetocalorie characteristics of these nanoparticle systems.

Gass, James

7

Magnetic nanoparticle temperature estimation.  

PubMed

The authors present a method of measuring the temperature of magnetic nanoparticles that can be adapted to provide in vivo temperature maps. Many of the minimally invasive therapies that promise to reduce health care costs and improve patient outcomes heat tissue to very specific temperatures to be effective. Measurements are required because physiological cooling, primarily blood flow, makes the temperature difficult to predict a priori. The ratio of the fifth and third harmonics of the magnetization generated by magnetic nanoparticles in a sinusoidal field is used to generate a calibration curve and to subsequently estimate the temperature. The calibration curve is obtained by varying the amplitude of the sinusoidal field. The temperature can then be estimated from any subsequent measurement of the ratio. The accuracy was 0.3 degree K between 20 and 50 degrees C using the current apparatus and half-second measurements. The method is independent of nanoparticle concentration and nanoparticle size distribution. PMID:19544801

Weaver, John B; Rauwerdink, Adam M; Hansen, Eric W

2009-05-01

8

Magnetic nanoparticle temperature estimation  

PubMed Central

The authors present a method of measuring the temperature of magnetic nanoparticles that can be adapted to provide in vivo temperature maps. Many of the minimally invasive therapies that promise to reduce health care costs and improve patient outcomes heat tissue to very specific temperatures to be effective. Measurements are required because physiological cooling, primarily blood flow, makes the temperature difficult to predict a priori. The ratio of the fifth and third harmonics of the magnetization generated by magnetic nanoparticles in a sinusoidal field is used to generate a calibration curve and to subsequently estimate the temperature. The calibration curve is obtained by varying the amplitude of the sinusoidal field. The temperature can then be estimated from any subsequent measurement of the ratio. The accuracy was 0.3 °K between 20 and 50?°C using the current apparatus and half-second measurements. The method is independent of nanoparticle concentration and nanoparticle size distribution. PMID:19544801

Weaver, John B.; Rauwerdink, Adam M.; Hansen, Eric W.

2009-01-01

9

DNA templated magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Recent discoveries in nanoscience are predicted to potentially revolutionize future technologies in an extensive number of fields. These developments are contingent upon discovering new and often unconventional methods to synthesize and control nanoscale components. Nature provides several examples of working nanotechnology such as the use of programmed self assembly to build and deconstruct complex molecular systems. We have adopted a method to control the one dimensional assembly of magnetic nanoparticles using DNA as a scaffold molecule. With this method we have demonstrated the ability to organize 5 nm particles into chains that stretch up to ˜20 mum in length. One advantage of using DNA compared is the ability of the molecule to interact with other biomolecules. After assembling particles onto DNA we have been able to cleave the molecule into smaller fragments using restriction enzymes. Using ligase enzymes we have re-connected these fragments, coated with either gold or iron oxide, to form long one-dimensional arrangements of the two different types of nanoparticles on a single molecular guide. We have also created a sensitive magnetic field sensor by incorporating magnetic nanoparticle coated DNA strands with microfabricated electrodes. The IV characteristics of the aligned nanoparticles are dependant on the magnitude of an externally applied magnetic field. This transport phenomenon known as tunneling magnetoresistance (TMR) shows room temperature resistance of our devices over 80% for cobalt ferrite coated DNA when a field of 20 kOe is applied. In comparison, studies using two dimensional nanoparticle films of irox oxides xii only exhibit a 35% MR effect. Confinement into one dimension using the DNA guide produces a TMR mechanism which produces significant increases in magnetoresistance. This property can be utilized for applications in magnetic field sensing, data storage, and logic elements.

Kinsella, Joseph M.

10

Uniform excitations in magnetic nanoparticles.  

PubMed

We present a short review of the magnetic excitations in nanoparticles below the superparamagnetic blocking temperature. In this temperature regime, the magnetic dynamics in nanoparticles is dominated by uniform excitations, and this leads to a linear temperature dependence of the magnetization and the magnetic hyperfine field, in contrast to the Bloch T(3/2) law in bulk materials. The temperature dependence of the average magnetization is conveniently studied by Mössbauer spectroscopy. The energy of the uniform excitations of magnetic nanoparticles can be studied by inelastic neutron scattering. PMID:21977393

Mørup, Steen; Frandsen, Cathrine; Hansen, Mikkel Fougt

2010-01-01

11

Uniform excitations in magnetic nanoparticles  

PubMed Central

Summary We present a short review of the magnetic excitations in nanoparticles below the superparamagnetic blocking temperature. In this temperature regime, the magnetic dynamics in nanoparticles is dominated by uniform excitations, and this leads to a linear temperature dependence of the magnetization and the magnetic hyperfine field, in contrast to the Bloch T 3/2 law in bulk materials. The temperature dependence of the average magnetization is conveniently studied by Mössbauer spectroscopy. The energy of the uniform excitations of magnetic nanoparticles can be studied by inelastic neutron scattering. PMID:21977393

Frandsen, Cathrine; Hansen, Mikkel Fougt

2010-01-01

12

Magnetic nanoparticles for theragnostics  

PubMed Central

Engineered magnetic nanoparticles (MNPs) represent a cutting-edge tool in medicine because they can be simultaneously functionalized and guided by a magnetic field. Use of MNPs has advanced magnetic resonance imaging (MRI), guided drug and gene delivery, magnetic hyperthermia cancer therapy, tissue engineering, cell tracking and bioseparation. Integrative therapeutic and diagnostic (i.e., theragnostic) applications have emerged with MNP use, such as MRI-guided cell replacement therapy or MRI-based imaging of cancer-specific gene delivery. However, mounting evidence suggests that certain properties of nanoparticles (e.g., enhanced reactive area, ability to cross cell and tissue barriers, resistance to biodegradation) amplify their cytotoxic potential relative to molecular or bulk counterparts. Oxidative stress, a 3-tier paradigm of nanotoxicity, manifests in activation of reactive oxygen species (ROS) (tier I), followed by a pro-inflammatory response (tier II) and DNA damage leading to cellular apoptosis and mutagenesis (tier III). In vivo administered MNPs are quickly challenged by macrophages of the reticuloendothelial system (RES), resulting in not only neutralization of potential MNP toxicity but also reduced circulation time necessary for MNP efficacy. We discuss the role of MNP size, composition and surface chemistry in their intracellular uptake, biodistribution, macrophage recognition and cytotoxicity, and review current studies on MNP toxicity, caveats of nanotoxicity assessments and engineering strategies to optimize MNPs for biomedical use. PMID:19389434

Shubayev, Veronica I.; Pisanic, Thomas R.; Jin, Sungho

2009-01-01

13

Enzymatic synthesis of magnetic nanoparticles.  

PubMed

We report the first in vitro enzymatic synthesis of paramagnetic and antiferromagnetic nanoparticles toward magnetic ELISA reporting. With our procedure, alkaline phosphatase catalyzes the dephosphorylation of l-ascorbic-2-phosphate, which then serves as a reducing agent for salts of iron, gadolinium, and holmium, forming magnetic precipitates of Fe45±14Gd5±2O50±15 and Fe42±4Ho6±4O52±5. The nanoparticles were found to be paramagnetic at 300 K and antiferromagnetic under 25 K. Although weakly magnetic at 300 K, the room-temperature magnetization of the nanoparticles found here is considerably greater than that of analogous chemically-synthesized LnxFeyOz (Ln = Gd, Ho) samples reported previously. At 5 K, the nanoparticles showed a significantly higher saturation magnetization of 45 and 30 emu/g for Fe45±14Gd5±2O50±15 and Fe42±4Ho6±4O52±5, respectively. Our approach of enzymatically synthesizing magnetic labels reduces the cost and avoids diffusional mass-transfer limitations associated with pre-synthesized magnetic reporter particles, while retaining the advantages of magnetic sensing. PMID:25854425

Kolhatkar, Arati G; Dannongoda, Chamath; Kourentzi, Katerina; Jamison, Andrew C; Nekrashevich, Ivan; Kar, Archana; Cacao, Eliedonna; Strych, Ulrich; Rusakova, Irene; Martirosyan, Karen S; Litvinov, Dmitri; Lee, T Randall; Willson, Richard C

2015-01-01

14

Modeling and simulation of magnetic nanoparticle sensor.  

PubMed

Sensitivity and detection limit of a magnetic nanoparticle sensor is modeled and simulated. A micro coil generates an alternating magnetic field which excites magnetic nanoparticles in its vicinity. A concentric sensing coil applies Faraday's law of induction measuring the excited magnetization of the magnetic particles at high frequency. A differential measurement compensates disturbances and the influence of the driving microcoil leaving only the signal caused by the magnetic particles. The sensing system can be used for detection of magnetic nanoparticle labels in immunological point of care diagnostics. The paper shows simulation results for a microcoil system capable of detecting a single superparamagnetic nanoparticle. PMID:17282422

Makiranta, Jarkko; Lekkala, Jukka

2005-01-01

15

Magnetic nanoparticle sensing: decoupling the magnetization from the excitation field  

PubMed Central

Remote sensing of magnetic nanoparticles has exciting applications for magnetic nanoparticle hyperthermia and molecular detection. We introduce, simulate, and experimentally demonstrate an innovation—a sensing coil that is geometrically decoupled from the excitation field—for magnetic nanoparticle spectroscopy that increases the flexibility and capabilities of remote detection. The decoupling enhances the sensitivity absolutely; to small amounts of nanoparticles, and relatively; to small changes in the nanoparticle dynamics. We adapt a previous spectroscopic method that measures the relaxation time of nanoparticles and demonstrate a new measurement of nanoparticle temperature that could potentially be used concurrently during hyperthermia. PMID:24610961

Reeves, Daniel B.; Weaver, John B.

2014-01-01

16

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.

17

Temperature dependent dissipation in magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

We parameterized the temperature dependent magnetic dissipation of iron oxide nanoparticles fixed in a frozen aqueous solution in an ac magnetic field. The magnetic power dissipated can be modeled by considering only Neel relaxation. This dissipation increased monotonically with temperature, increasing by approximately 50% between -40 °C and -10 °C. These experimental results provide quantitative confirmation for the Neel model of magnetic dissipative heating for nanoparticles rigidly confined in a solid matrix. We also find substantial temperature dependence in the magnetic dissipation of nanoparticles suspended in a liquid, which has important consequences for potential applications of magnetic nanoparticles for hyperthermia.

Regmi, R.; Naik, A.; Thakur, J. S.; Vaishnava, P. P.; Lawes, G.

2014-05-01

18

Intravenous magnetic nanoparticle cancer hyperthermia  

PubMed Central

Magnetic nanoparticles heated by an alternating magnetic field could be used to treat cancers, either alone or in combination with radiotherapy or chemotherapy. However, direct intratumoral injections suffer from tumor incongruence and invasiveness, typically leaving undertreated regions, which lead to cancer regrowth. Intravenous injection more faithfully loads tumors, but, so far, it has been difficult achieving the necessary concentration in tumors before systemic toxicity occurs. Here, we describe use of a magnetic nanoparticle that, with a well-tolerated intravenous dose, achieved a tumor concentration of 1.9 mg Fe/g tumor in a subcutaneous squamous cell carcinoma mouse model, with a tumor to non-tumor ratio > 16. With an applied field of 38 kA/m at 980 kHz, tumors could be heated to 60°C in 2 minutes, durably ablating them with millimeter (mm) precision, leaving surrounding tissue intact. PMID:23901270

Huang, Hui S; Hainfeld, James F

2013-01-01

19

New magnetic nanoparticles for biotechnology.  

PubMed

Paramagnetic carriers, which are linked to antibodies enable highly specific biological cell separations. With the colloidal synthesis of superparamagnetic Co and FeCo nanocrystals with superior magnetic moments the question about their potential to replace magnetite as the magnetically responsive component of magnetic beads is addressed. Starting from a magnetic analysis of the corresponding magnetophoretic mobility of Co and FeCo based alloys their synthesis and resulting microstructural and magnetic properties as function of the underlying particle size distribution are discussed in detail. The stability of the oleic acid ligand of Co nanocrystals has been investigated. The oxidation kinetics were quantified using magnetic measurements. As a result, this ligand system provides sufficient protection against oxidation. Furthermore, the kinetics of the synthesis of Fe(50)Co(50) nanoparticles has been monitored employing Fourier transform infra red (FT-IR) spectroscopy and is modeled using a consecutive decomposition and growth model. This model predicts the experimentally realized FeCo nanoparticle composition as a function of the particle size fairly well. High-resolution transmission electron microscopy (HRTEM) was performed to uncover the resulting microstructure and composition on a nanometer scale. PMID:15288940

Hütten, Andreas; Sudfeld, Daniela; Ennen, Inga; Reiss, Günter; Hachmann, Wiebke; Heinzmann, Ulrich; Wojczykowski, Klaus; Jutzi, Peter; Saikaly, Wahib; Thomas, Gareth

2004-08-26

20

Magnetic nanoparticles with combined anisotropy  

NASA Astrophysics Data System (ADS)

We study the influence of the distribution of the particles' aspect ratio on the magnetostatic properties of an assembly of nanoparticles with cubic magnetocrystalline anisotropy, such as iron, nickel, iron oxides, and ferrites. Because of the large values of the dimensionless ratio Ms2/|Kc| for these particles, the shape anisotropy energy makes considerable contribution to the total nanoparticle energy even for relatively small shape distortions, with equivalent ellipsoids having aspect ratios ? ? 1.1. As a result, the magnetostatic properties of a randomly oriented assembly of particles with combined anisotropy at ? ? 1.1 are similar to those for an assembly of particles with purely uniaxial magnetic anisotropy. This conclusion is shown to be valid not only for the assembly hysteresis loops but also for the magnetic relaxation characteristics, at least in the high damping limit.

Usov, N. A.; Barandiarán, J. M.

2012-09-01

21

Magnetic nanoparticle biodistribution following intratumoral administration  

Microsoft Academic Search

Recently, heat generated by iron oxide nanoparticles (IONPs) stimulated by an alternating magnetic field (AMF) has shown promise in the treatment of cancer. To determine the mechanism of nanoparticle-induced cytotoxicity, the physical association of the cancer cells and the nanoparticles must be determined. We have used transmission electron microscopy (TEM) to define the time dependent cellular uptake of intratumorally administered

A. J. Giustini; R. Ivkov; P. J. Hoopes

2011-01-01

22

Engineering biofunctional magnetic nanoparticles for biotechnological applications  

NASA Astrophysics Data System (ADS)

Synthesis and characterization of magnetic nanoparticles with excellent size control are showed here. Their functionalization using an amphiphilic polymer is also described. This strategy allows the stabilization of magnetic nanoparticles in aqueous solvents and in addition, the polymer shell serves as a platform to incorporate relevant biomolecules, such as poly(ethylene glycol) and a number of carbohydrates. Nanoparticles functionalized with carbohydrates show the ability to avoid unspecific interactions between proteins present in the working medium and the nanoparticles, so can be used as an alternative to poly(ethylene glycol) molecules. Results confirm these nanoparticles as excellent contrast agents for magnetic resonance imaging. Changes in the spin-spin transversal relaxation times of the surrounding water protons due to nanoparticle aggregation demonstrates the bioactivity of these nanoparticles functionalized with carbohydrates. To finish with, nanoparticle toxicity is evaluated by means of MTT assay. The obtained results clearly indicate that these nanoparticles are excellent candidates for their further application in nanomedicine or nanobiotechnology.Synthesis and characterization of magnetic nanoparticles with excellent size control are showed here. Their functionalization using an amphiphilic polymer is also described. This strategy allows the stabilization of magnetic nanoparticles in aqueous solvents and in addition, the polymer shell serves as a platform to incorporate relevant biomolecules, such as poly(ethylene glycol) and a number of carbohydrates. Nanoparticles functionalized with carbohydrates show the ability to avoid unspecific interactions between proteins present in the working medium and the nanoparticles, so can be used as an alternative to poly(ethylene glycol) molecules. Results confirm these nanoparticles as excellent contrast agents for magnetic resonance imaging. Changes in the spin-spin transversal relaxation times of the surrounding water protons due to nanoparticle aggregation demonstrates the bioactivity of these nanoparticles functionalized with carbohydrates. To finish with, nanoparticle toxicity is evaluated by means of MTT assay. The obtained results clearly indicate that these nanoparticles are excellent candidates for their further application in nanomedicine or nanobiotechnology. Electronic supplementary information (ESI) available: Chemical, physical and magnetic characterization; R2 maps; stability of NPs at different conditions; size of glucose NPs in the presence of Concanavalin A; MTT assays of the samples are shown in figures S1-S10. Table S1 represents the hydrodynamic size of PMAO NPs after being washed with different solvents. See DOI: 10.1039/c0nr00104j

Moros, Maria; Pelaz, Beatriz; López-Larrubia, Pilar; García-Martin, Maria L.; Grazú, Valeria; de La Fuente, Jesus M.

2010-09-01

23

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

24

Platinum dendritic nanoparticles with magnetic behavior  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles have attracted increasing attention for biomedical applications in magnetic resonance imaging, high frequency magnetic field hyperthermia therapies, and magnetic-field-gradient-targeted drug delivery. In this study, three-dimensional (3D) platinum nanostructures with large surface area that features magnetic behavior have been demonstrated. The well-developed 3D nanodendrites consist of plentiful interconnected nano-arms ˜4 nm in size. The magnetic behavior of the 3D dendritic Pt nanoparticles is contributed by the localization of surface electrons due to strongly bonded oxygen/Pluronic F127 and the local magnetic moment induced by oxygen vacancies on the neighboring Pt and O atoms. The magnetization of the nanoparticles exhibits a mixed paramagnetic and ferromagnetic state, originating from the core and surface, respectively. The 3D nanodendrite structure is suitable for surface modification and high amounts of drug loading if the transition temperature was enhanced to room temperature properly.

Li, Wenxian; Sun, Ziqi; Tian, Dongliang; Nevirkovets, Ivan P.; Dou, Shi-Xue

2014-07-01

25

Platinum dendritic nanoparticles with magnetic behavior  

SciTech Connect

Magnetic nanoparticles have attracted increasing attention for biomedical applications in magnetic resonance imaging, high frequency magnetic field hyperthermia therapies, and magnetic-field-gradient-targeted drug delivery. In this study, three-dimensional (3D) platinum nanostructures with large surface area that features magnetic behavior have been demonstrated. The well-developed 3D nanodendrites consist of plentiful interconnected nano-arms ?4?nm in size. The magnetic behavior of the 3D dendritic Pt nanoparticles is contributed by the localization of surface electrons due to strongly bonded oxygen/Pluronic F127 and the local magnetic moment induced by oxygen vacancies on the neighboring Pt and O atoms. The magnetization of the nanoparticles exhibits a mixed paramagnetic and ferromagnetic state, originating from the core and surface, respectively. The 3D nanodendrite structure is suitable for surface modification and high amounts of drug loading if the transition temperature was enhanced to room temperature properly.

Li, Wenxian, E-mail: wl240@uowmail.edu.au [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW 2522 (Australia); Solar Energy Technologies, School of Computing, Engineering, and Mathematics, University of Western Sydney, Penrith NSW 2751 (Australia); Sun, Ziqi; Nevirkovets, Ivan P.; Dou, Shi-Xue [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW 2522 (Australia); Tian, Dongliang [Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of the Ministry of Education, School of Chemistry and the Environment, Beihang University, Beijing 100191 (China)

2014-07-21

26

Spherical magnetic nanoparticles: magnetic structure and interparticle interaction  

E-print Network

Spherical magnetic nanoparticles: magnetic structure and interparticle interaction V. Russier on the case where the particles present a vortex structure. In a first step the local magnetic structure constant. When the particles magnetization present a vortex structure, it is shown that the polarization

Paris-Sud XI, Université de

27

Fluorescent Magnetic Nanoparticles for Biomedical Applications  

E-print Network

In recent years, bifunctional nanoprobes with both magnetic and fluorescent properties have received a lot% Cells were incubated for 24h with SPIONs@SiO2. Cellular iron was determined by measuring the magneticFluorescent Magnetic Nanoparticles for Biomedical Applications V.M.Dao, Dr. G. Coullerez, Dr. L

Candea, George

28

Bioavailability of magnetic nanoparticles to the brain  

NASA Astrophysics Data System (ADS)

This study investigates the bioavailability of carboxymethyl dextran-coated magnetic nanoparticles (CMD-MNP) to the brain. The cytotoxicity of CMD-MNP was assessed by co-culture with C6, a rat glioma cell line. To investigate the effects of an external magnetic field on the biodistribution of nanoparticles in a rat model, a magnet of 0.3 Tesla was applied externally over the cranium and the particles injected via the external jugular vein. Nanoparticles were also injected into rats implanted with C6 tumor cells. Staining of histological samples with Prussian blue to detect iron particles revealed that the external magnetic field enhanced the aggregation of nanoparticles in the rat brain; this enhancement was even more pronounced in the tumor region.

Huang, Bor-Ren; Chen, Pin-Yuan; Huang, Chiung-Yin; Jung, Shih-Ming; Ma, Yunn-Hwa; Wu, Tony; Chen, Jyh-Ping; Wei, Kuo-Chen

2009-05-01

29

Magnetic nanoparticle-based cancer therapy  

NASA Astrophysics Data System (ADS)

Nanoparticles (NPs) with easily modified surfaces have been playing an important role in biomedicine. As cancer is one of the major causes of death, tremendous efforts have been devoted to advance the methods of cancer diagnosis and therapy. Recently, magnetic nanoparticles (MNPs) that are responsive to a magnetic field have shown great promise in cancer therapy. Compared with traditional cancer therapy, magnetic field triggered therapeutic approaches can treat cancer in an unconventional but more effective and safer way. In this review, we will discuss the recent progress in cancer therapies based on MNPs, mainly including magnetic hyperthermia, magnetic specific targeting, magnetically controlled drug delivery, magnetofection, and magnetic switches for controlling cell fate. Some recently developed strategies such as magnetic resonance imaging (MRI) monitoring cancer therapy and magnetic tissue engineering are also addressed.

Yu, Jing; Huang, Dong-Yan; Muhammad Zubair, Yousaf; Hou, Yang-Long; Gao, Song

2013-02-01

30

Heating efficiency in magnetic nanoparticle hyperthermia  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles for hyperthermic treatment of cancers have gained significant attention in recent years. In magnetic hyperthermia, three independent mechanisms result in thermal energy upon stimulation: Néel relaxation, Brownian relaxation, and hysteresis loss. The relative contribution of each is strongly dependent on size, shape, crystalline anisotropy, and degree of aggregation or agglomeration of the nanoparticles. We review the effects of each of these physical mechanisms in light of recent experimental studies and suggest routes for progress in the field.

Deatsch, Alison E.; Evans, Benjamin A.

2014-03-01

31

Current methods for synthesis of magnetic nanoparticles.  

PubMed

The synthesis of different kinds of magnetic nanoparticles (MNPs) has attracted much attention. During the last few years, a large portion of the articles published about MNPs have described efficient routes to attain shape-controlled and highly stable MNPs with narrow size distribution. In this review, we have reported several popular methods including co-precipitation, microemulsion, thermal decomposition, solvothermal, sonochemical, microwave-assisted, chemical vapor deposition, combustion, carbon arc, and laser pyrolysis, for the synthesis of magnetic nanoparticles. PMID:25435409

Majidi, Sima; Zeinali Sehrig, Fatemeh; Farkhani, Samad Mussa; Soleymani Goloujeh, Mehdi; Akbarzadeh, Abolfazl

2014-12-01

32

Alignment of Magnetic Nanoparticles in Polymer Films  

NASA Astrophysics Data System (ADS)

Polymer nanocomposites are advanced materials, which are obtained by the addition of natural or synthetic nanosized inorganic fillers into the polymeric material. The addition of trace amounts of nanoparticles could enhance the polymer's mechanical, thermal, electrical and optical properties due to their size and high surface area/volume ratio. In this work, magnetite/PMMA nanocomposites were prepared either by randomly dispersing or by aligning magnetite nanoparticles in the matrix using an external magnetic field. Oleic acid coated iron oxide nanoparticles (magnetite) were used as nanofiller. 7-9 nm iron oxide nanoparticles were synthesized by co-precipitation method with different surfactant amounts and at different synthesis temperatures. Superparamagnetic property of bare iron oxides was confirmed by Vibrating Sample Magnetometer (VSM) analysis. Thermogravimetric Analysis (TGA) measurements were used to calculate the surface coverage of the oleic acid on iron nanoparticles, which increases with increasing oleic acid concentration and consistent across synthesis temperature. Dispersion and alignment of nanoparticles through the polymer film were investigated with TEM and SEM. Results showed that magnetic nanoparticles formed under the influence of an external magnetic field were aligned and formed rods consisting of individual nanoparticles.

Yarar, Ecem; Rende, Deniz; Bucak, Seyda

2013-03-01

33

Improving magnetic properties of ultrasmall magnetic nanoparticles by biocompatible coatings  

NASA Astrophysics Data System (ADS)

This paper deals with the effect of a biocompatible surface coating layer on the magnetic properties of ultrasmall iron oxide nanoparticles. Particles were synthesized by laser pyrolysis and fully oxidized to maghemite by acid treatment. The surface of the magnetic nanoparticles was systematically coated with either phosphonate (phosphonoacetic acid or pamidronic acid) or carboxylate-based (carboxymethyl dextran) molecules and the binding to the nanoparticle surface was analyzed. Magnetic properties at low temperature show a decrease in coercivity and an increase in magnetization after the coating process. Hysteresis loop displacement after field cooling is significantly reduced by the coating, in particular, for particles coated with pamidronic acid, which show a 10% reduction of the displacement of the loop. We conclude that the chemical coordination of carboxylates and phosphonates reduces the surface disorder and enhances the magnetic properties of ultrasmall maghemite nanoparticles.

Costo, R.; Morales, M. P.; Veintemillas-Verdaguer, S.

2015-02-01

34

Thermal potentiation of chemotherapy by magnetic nanoparticles  

PubMed Central

Clinical studies have demonstrated the effectiveness of hyperthermia as an adjuvant for chemotherapy and radiotherapy. However, significant clinical challenges have been encountered, such as a broader spectrum of toxicity, lack of patient tolerance, temperature control and significant invasiveness. Hyperthermia induced by magnetic nanoparticles in high-frequency oscillating magnetic fields, commonly termed magnetic fluid hyperthermia, is a promising form of heat delivery in which thermal energy is supplied at the nanoscale to the tumor. This review discusses the mechanisms of heat dissipation of iron oxide-based magnetic nanoparticles, current methods and challenges to deliver heat in the clinic, and the current work related to the use of magnetic nanoparticles for the thermal-chemopotentiation of therapeutic drugs. PMID:24074390

Torres-Lugo, Madeline; Rinaldi, Carlos

2014-01-01

35

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

36

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

37

Targeted delivery of multifunctional magnetic nanoparticles.  

PubMed

Magnetic nanoparticles and their magnetofluorescent analogues have become important tools for in vivo imaging using magnetic resonance imaging and fluorescent optical methods. A number of monodisperse magnetic nanoparticle preparations have been developed over the last decade for angiogenesis imaging, cancer staging, tracking of immune cells (monocyte/macrophage, T cells) and for molecular and cellular targeting. Phage display and data mining have enabled the procurement of novel tissue- or receptor-specific peptides, while high-throughput screening of diversity-oriented synthesis libraries has identified small molecules that permit or prevent uptake by specific cell types. Next-generation magnetic nanoparticles are expected to be truly multifunctional, incorporating therapeutic functionalities and further enhancing an already diverse repertoire of capabilities. PMID:17716118

McCarthy, Jason R; Kelly, Kimberly A; Sun, Eric Y; Weissleder, Ralph

2007-04-01

38

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

39

Targeting intracellular compartments by magnetic polymeric nanoparticles.  

PubMed

Superparamagnetic iron oxide nanoparticles (SPIONs) show a great promise for a wide specter of bioapplications, due to their characteristic magnetic properties exhibited only in the presence of magnetic field. Their advantages in the fields of magnetic drug targeting and imaging are well established and their safety is assumed, since iron oxide nanoparticles have already been approved for in vivo application, however, according to many literature reports the bare metal oxide nanoparticles may cause toxic effects on treated cells. Therefore, it is reasonable to prevent the direct interactions between metal oxide core and surrounding environment. In the current research ricinoleic acid coated maghemite nanoparticles were successfully synthesized, characterized and incorporated in the polymeric matrix, resulting in nanosized magnetic polymeric particles. The carrier system was shown to exhibit superparamagnetic properties and was therefore responsive towards external magnetic field. Bioevaluation using T47-D breast cancer cells confirmed internalization of magnetic polymeric nanoparticles (MNPs) and their intracellular localization in various subcellular compartments, depending on presence/absence of external magnetic field. However, the number of internalized MNPs observed by fluorescent and transmission electron microscopy was relatively low, making such way of targeting effective only for delivery of highly potent drugs. The scanning electron microscopy of treated cells revealed that MNPs influenced the cell adhesion, when external magnetic field was applied, and that treatment resulted in damaged apical plasma membrane right after exposure to the magnetic carrier. On the other hand, MNPs showed only reversibly reduced cellular metabolic activity in concentrations up to 200 ?g/ml and, in the tested concentration the cell cycle distribution was within the normal range, indicating safety of the established magnetic carrier system for the treated cells. PMID:23603023

Kocbek, Petra; Kralj, Slavko; Kreft, Mateja Erdani; Kristl, Julijana

2013-09-27

40

Aptamer conjugated magnetic nanoparticles as nanosurgeons  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles have shown promise in the fields of targeted drug delivery, hyperthermia and magnetic resonance imaging (MRI) in cancer therapy. The ability of magnetic nanoparticles to undergo surface modification and the effect of external magnetic field in the dynamics of their movement make them an excellent nanoplatform for cancer destruction. Surgical removal of cancerous or unwanted cells selectively from the interior of an organ or tissue without any collateral damage is a serious problem due to the highly infiltrative nature of cancer. To address this problem in surgery, we have developed a nanosurgeon for the selective removal of target cells using aptamer conjugated magnetic nanoparticles controlled by an externally applied three-dimensional rotational magnetic field. With the help of the nanosurgeon, we were able to perform surgical actions on target cells in in vitro studies. LDH and intracellular calcium release assay confirmed the death of cancer cells due to the action of the nanosurgeon which in turn nullifies the possibility of proliferation by the removed cells. The nanosurgeon will be a useful tool in the medical field for selective surgery and cell manipulation studies. Additionally, this system could be upgraded for the selective removal of complex cancers from diverse tissues by incorporating various target specific ligands on magnetic nanoparticles.

Nair, Baiju G.; Nagaoka, Yutaka; Morimoto, Hisao; Yoshida, Yasuhiko; Maekawa, Toru; Sakthi Kumar, D.

2010-11-01

41

Functionalized magnetic nanoparticles: A novel heterogeneous catalyst support  

EPA Science Inventory

Functionalized magnetic nanoparticles have emerged as viable alternatives to conventional materials, as robust, high-surface-area heterogeneous catalyst supports. Post-synthetic surface modification protocol for magnetic nanoparticles has been developed that imparts desirable che...

42

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

43

Magnetic nanoparticles in MgB2  

NASA Astrophysics Data System (ADS)

Additional pinning generated by magnetic nanoparticles which were created or inserted within polycrystalline MgB2 superconductor is analyzed. The composites were built in two ways: (i) ceramization of polysiloxane-co-ferrocene based copolymers and (ii) insertion of coated nanoparticles. The composites present two types of pinning: core pinning based on the variation of the superconducting parameter when a non-superconducting particle is present and a magnetic pinning resulting from the interaction of the screening currents around the particle and the flux line. All samples show a consistent improvement of the critical current density when the magnetic moment of the sample in normal state is finite but small, showing a maximum for a magnetic moment of 0.015 emu/cm3. A tentative description of the effect of magnetic pinning is presented in the framework of the collective pinning.

Sandu, Viorel; Chee, Ching Yern

2014-03-01

44

Microfluidic Biosensing Systems Using Magnetic Nanoparticles  

PubMed Central

In recent years, there has been rapidly growing interest in developing hand held, sensitive and cost-effective on-chip biosensing systems that directly translate the presence of certain bioanalytes (e.g., biomolecules, cells and viruses) into an electronic signal. The impressive and rapid progress in micro- and nanotechnology as well as in biotechnology enables the integration of a variety of analytical functions in a single chip. All necessary sample handling and analysis steps are then performed within the chip. Microfluidic systems for biomedical analysis usually consist of a set of units, which guarantees the manipulation, detection and recognition of bioanalytes in a reliable and flexible manner. Additionally, the use of magnetic fields for performing the aforementioned tasks has been steadily gaining interest. This is because magnetic fields can be well tuned and applied either externally or from a directly integrated solution in the biosensing system. In combination with these applied magnetic fields, magnetic nanoparticles are utilized. Some of the merits of magnetic nanoparticles are the possibility of manipulating them inside microfluidic channels by utilizing high gradient magnetic fields, their detection by integrated magnetic microsensors, and their flexibility due to functionalization by means of surface modification and specific binding. Their multi-functionality is what makes them ideal candidates as the active component in miniaturized on-chip biosensing systems. In this review, focus will be given to the type of biosening systems that use microfluidics in combination with magnetoresistive sensors and detect the presence of bioanalyte tagged with magnetic nanoparticles. PMID:24022689

Giouroudi, Ioanna; Keplinger, Franz

2013-01-01

45

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

46

Cold plasma treatment of magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

This thesis investigates the application of cold plasma to remove the oleic acid bonded on magnetic nanoparticles: SmCo5 nanoflakes prepared via surfactant assisted high energy ball milling and CoFe2O 4 nanoparticles prepared via chemical synthesis. Oleic acid molecules bonded on nanoparticles are in the carboxylate form which could not be washed away by organic solvents in ultrasonic bath; only free oleic acid molecules left on the nanoparticle surface after ball milling can be washed away through ultrasonic bath. High temperature annealing method works for removing oleic acid but nanoparticles would be damaged because of oxidation and decomposition. The RF cold plasma has advantages over above methods as the plasma temperature is typically around room temperature, and the energetic ions could strike away carboxylate molecules bonded on the surface of nanoparticles without changing the surface chemistry. Powder X-ray diffraction (XRD) was performed to see if there was phase transformation, decomposition during plasma treatment. The content change of oleic acid molecules on the nanoparticles surface was confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR).

Wang, Ke

47

Magnetic Nanoparticles for Cancer Diagnosis and Therapy  

PubMed Central

Nanotechnology is evolving as a new field that has a potentially high research and clinical impact. Medicine, in particular, could benefit from nanotechnology, due to emerging applications for noninvasive imaging and therapy. One important nanotechnological platform that has shown promise includes the so-called iron oxide nanoparticles. With specific relevance to cancer therapy, iron oxide nanoparticle-based therapy represents an important alternative to conventional chemotherapy, radiation, or surgery. Iron oxide nanoparticles are usually composed of three main components: an iron core, a polymer coating, and functional moieties. The biodegradable iron core can be designed to be superparamagnetic. This is particularly important, if the nanoparticles are to be used as a contrast agent for noninvasive magnetic resonance imaging (MRI). Surrounding the iron core is generally a polymer coating, which not only serves as a protective layer but also is a very important component for transforming nanoparticles into biomedical nanotools for in vivo applications. Finally, different moieties attached to the coating serve as targeting macromolecules, therapeutics payloads, or additional imaging tags. Despite the development of several nanoparticles for biomedical applications, we believe that iron oxide nanoparticles are still the most promising platform that can transform nanotechnology into a conventional medical discipline. PMID:22274558

Yigit, Mehmet V.; Moore, Anna

2013-01-01

48

Multifunctional magnetic nanoparticles for magnetic resonance imaging and cancer therapy  

Microsoft Academic Search

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

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

2011-01-01

49

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

50

Static magnetic properties of Maghemite nanoparticles  

NASA Astrophysics Data System (ADS)

We report the static magnetic properties of Maghemite (?-Fe2O3) nanoparticles with an average crystallite size of 14 ± 1.8 nm synthesized via a co-precipitation method. The zero-field-cooled (ZFC) and the field-cooled (FC) magnetization measurements were performed using a physical properties measurements system (PPMS) at temperatures from 5 K to 300 K. The ZFC/FC measurements showed a typical superparamagnetic behavior with a narrow size distribution.

Zulfiqar; Rahman, Muneeb Ur; Usman, M.; Hasanain, Syed Khurshid; Zia-ur-Rahman; Ullah, Amir; Kim, Ill Won

2014-12-01

51

Biomedical and environmental applications of magnetic nanoparticles  

Microsoft Academic Search

This paper presents an overview of syntheses and applications of magnetic nanoparticles (MNPs) at the Institute of Materials Science, Vietnam Academy of Science and Technology. Three families of oxide MNPs, magnetite, manganite and spinel ferrite materials, were prepared in various ways: coprecipitation, sol–gel and high energy mechanical milling. Basic properties of MNPs were characterized by Vibrating Sample Magnetometer (VSM) and

Dai Lam Tran; Van Hong Le; Hoai Linh Pham; Thi My Nhung Hoang; Thi Quy Nguyen; Thien Tai Luong; Phuong Thu Ha; Xuan Phuc Nguyen

2010-01-01

52

EDITORIAL: Biomedical applications of magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic materials have been used with grain sizes down to the nanoscale for longer than any other type of material. This is because of a fundamental change in the magnetic structure of ferro- and ferrimagnetic materials when grain sizes are reduced. In these circumstances, the normal macroscopic domain structure transforms into a single domain state at a critical size which typically lies below 100 nm. Once this transformation occurs the mechanism of magnetisation reversal can only be via the rotation of the magnetisation vector from one magnetic easy axis to another via a magnetically hard direction. This change of reversal mechanism has led to a new class of magnetic materials whose properties and the basic underlying physical mechanism governing them were defined in a seminal work first published by E C Stoner and E P Wolhfarth in 1949. As a consequence of this rotation mechanism, magnetic nanoparticles exist having coercivities which are highly controllable and lie between soft materials and normal permanent magnet materials. This ability to control coercivity in such particles has led to a number of significant technological advances, particularly in the field of information storage. The high value of information storage technology has meant that since the 1950s an enormous research and development effort has gone into techniques for the preparation of magnetic particles and thin films having well defined properties. Hence, certainly since the 1960s, a wide range of techniques to produce both metallic and oxide magnetic nanoparticles with sizes ranging from 4-100 nm has been developed. The availability of this wide range of materials led to speculation from the 1960s onwards that they may have applications in biology and medicine. The fact that a magnetic field gradient can be used to either remotely position or selectively filter biological materials leads to a number of obvious applications. These applications fall broadly into two categories: those involving the use in-vivo and those involving the use of magnetic particles in-vitro. Obviously for safety reasons the development of in-vitro applications are more accessible. However, and somewhat ironically, the one application currently used on a significant scale involves the use of magnetic particles to produce a distortion in the magnetic field at a given site under examination via magnetic resonance imaging (MRI). The presence of the particles at a given site can alter the contrast of certain types of cells by several orders of magnitude, making visible objects that were hitherto difficult to image. With the increasing sophistication of pharmaceuticals, the dramatic development of cell manipulation and even DNA sequencing, the possibility of using magnetic nanoparticles to improve the effectiveness of such technologies is obviously appealing. Hence there are proposals for drug delivery systems, particularly for anti-inflammatory agents and also for the use of magnetic separation technologies for rapid DNA sequencing. A further and somewhat surprising application of magnetic nanoparticles lies in the production of controlled heating effects. Each cycle of a hysteresis loop of any magnetic material involves an energy loss proportional to the area of the loop. Hence if magnetic nanoparticles having the required coercivity are remotely positioned at a given site in the body, perhaps the site of a malignancy, then the application of an alternating magnetic field can be used to selectively warm a given area. It has been proposed that this simple physical effect could be used both to destroy cells directly or to induce a modest increase in temperature so as to increase the efficacy of either chemotherapy or radiotherapy. Clearly this area of potential technology is highly novel and offers many exciting possibilities for future developments. The area is relatively young and highly multidisciplinary, requiring a range of scientific knowledge from inorganic chemistry involved in the preparation of the nanoparticles, through biochemistry and medical science to allow for

O'Grady, K.

2002-07-01

53

Multifunctional Magnetic Nanoparticles for Medical Imaging Applications  

PubMed Central

Magnetic nanoparticles (MNPs) have attracted enormous research attention due to their unique magnetic properties that enable the detection by the non-invasive medical imaging modality—magnetic resonance imaging (MRI). By incorporating advanced features, such as specific targeting, multimodality, therapeutic delivery, the detectability and applicability of MNPs have been dramatically expanded. A delicate design on structure, composition and surface chemistry is essential to achieving desired properties in MNP systems, such as high imaging contrast and chemical stability, non-fouling surface, target specificity and/or multimodality. This article presents the design fundamentals on the development of MNP systems, from discussion of material selection for nanoparticle cores and coatings, strategies for chemical synthesis and surface modification and their merits and limitations, to conjugation of special biomolecules for intended functions, and reviews the recent advances in the field. PMID:20593005

Fang, Chen; Zhang, Miqin

2010-01-01

54

Nonlinear simulations to optimize magnetic nanoparticle hyperthermia  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticle hyperthermia is an attractive emerging cancer treatment, but the acting microscopic energy deposition mechanisms are not well understood and optimization suffers. We describe several approximate forms for the characteristic time of Néel rotations with varying properties and external influences. We then present stochastic simulations that show agreement between the approximate expressions and the micromagnetic model. The simulations show nonlinear imaginary responses and associated relaxational hysteresis due to the field and frequency dependencies of the magnetization. This suggests that efficient heating is possible by matching fields to particles instead of resorting to maximizing the power of the applied magnetic fields.

Reeves, Daniel B.; Weaver, John B.

2014-03-01

55

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

56

Nonlinear simulations to optimize magnetic nanoparticle hyperthermia  

PubMed Central

Magnetic nanoparticle hyperthermia is an attractive emerging cancer treatment, but the acting microscopic energy deposition mechanisms are not well understood and optimization suffers. We describe several approximate forms for the characteristic time of Néel rotations with varying properties and external influences. We then present stochastic simulations that show agreement between the approximate expressions and the micromagnetic model. The simulations show nonlinear imaginary responses and associated relaxational hysteresis due to the field and frequency dependencies of the magnetization. This suggests that efficient heating is possible by matching fields to particles instead of resorting to maximizing the power of the applied magnetic fields. PMID:24753618

Reeves, Daniel B.; Weaver, John B.

2014-01-01

57

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

58

Electrical detection of individual magnetic nanoparticles encapsulated in carbon nanotubes.  

PubMed

We report on low-temperature electrical transport measurements of single-walled carbon nanotubes (SWNTs) filled in their inner core with one-dimensional cobalt nanoparticles. The electrical transport properties of the hybrid devices are strongly sensitive to the magnetization reversal of isolated magnetic nanoparticles, resulting in strong hysteretic variations of the magnetoconductance. The magnetic anisotropy of a one-dimensional encapsulated cobalt nanoparticle is investigated, establishing an unusually strong dominating contribution of magnetic surface anisotropy. PMID:21344889

Cleuziou, Jean-Pierre; Wernsdorfer, Wolfgang; Ondarçuhu, Thierry; Monthioux, Marc

2011-03-22

59

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

60

Magnetic properties of metallic ferromagnetic nanoparticle composites  

NASA Astrophysics Data System (ADS)

Magnetic properties of nanoparticle composites, consisting of aligned ferromagnetic nanoparticles embedded in a nonmagnetic matrix, have been determined using a model based on phenomenological approaches. Input materials parameters for this model include the saturation magnetization (Ms), the crystal anisotropy field (Hk), a damping parameter (?) that describes the magnetic losses in the particles, and the conductivity (?) of the particles; all particles are assumed to have identical properties. Control of the physical characteristics of the composite system—such as the particle size, shape, volume fraction, and orientation—is necessary in order to achieve optimal magnetic properties (e.g., the magnetic permeability) at GHz frequencies. The degree to which the physical attributes need to be controlled has been determined by analysis of the ferromagnetic resonance (FMR) and eddy current losses at varying particle volume fractions. Composites with approximately spherical particles with radii smaller than 100 nm (for the materials parameters chosen here), packed to achieve a thin film geometry (with the easy magnetization axes of all particles aligned parallel to each other and to the surface of the thin film) are expected to have low eddy current losses, and optimal magnetic permeability and FMR behavior.

Ramprasad, R.; Zurcher, P.; Petras, M.; Miller, M.; Renaud, P.

2004-07-01

61

Thermoresponsive magnetic nanoparticles for seawater desalination.  

PubMed

Thermoresponsive magnetic nanoparticles (MNPs) as a class of smart materials that respond to a change in temperature may by used as a draw solute to extract water from brackish or seawater by forward osmosis (FO). A distinct advantage is the efficient regeneration of the draw solute and the recovery of water via heat-facilitated magnetic separation. However, the osmotic pressure attained by this type of draw solution is too low to counteract that of seawater. In this work, we have designed a FO draw solution based on multifunctional Fe3O4 nanoparticles grafted with copolymer poly(sodium styrene-4-sulfonate)-co-poly(N-isopropylacrylamide) (PSSS-PNIPAM). The resulting regenerable draw solution shows high osmotic pressure for seawater desalination. This is enabled by three essential functional components integrated within the nanostructure: (i) a Fe3O4 core that allows magnetic separation of the nanoparticles from the solvent, (ii) a thermoresponsive polymer, PNIPAM, that enables reversible clustering of the particles for further improved magnetic capturing at a temperature above its low critical solution temperature (LCST), and (iii) a polyelectrolyte, PSSS, that provides an osmotic pressure that is well above that of seawater. PMID:24134565

Zhao, Qipeng; Chen, Ningping; Zhao, Dieling; Lu, Xianmao

2013-11-13

62

Photoconjugation of molecularly imprinted polymer with magnetic nanoparticles.  

PubMed

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 photocoupling chemistry to enable simple conjugation of MIP nanoparticles with inorganic magnetic nanoparticles. We first synthesized MIP nanoparticles using propranolol as a model template and perfluorophenyl azide-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 nondestructive 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 photocatalysts. PMID:23673293

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

2013-06-12

63

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

64

Magnetic microreactors for efficient and reliable magnetic nanoparticle surface functionalization.  

PubMed

Microreactors have attracted wide attention in the nano- and biotechnology fields because they offer many advantages over standard liquid phase reactions. We report the development of a magnetic microreactor for reliable, fast and efficient surface functionalization of superparamagnetic iron oxide nanoparticles (SPIONs). A comprehensive study of the development process in terms of setup, loading capacity and efficiency is described. We performed experimental and computational studies in order to evaluate the trapping efficiencies, maximum loading capacity and magnetic alignment of the nanoparticles. The results showed that capacity and trapping efficiencies are directly related to the flow rate, elution time and reactor type. Based on our results and the developed magnetic microreactor, we describe a model multistep surface derivatization procedure of SPIONs. PMID:24817177

Digigow, R G; Dechézelles, J-F; Kaufmann, J; Vanhecke, D; Knapp, H; Lattuada, M; Rothen-Rutishauser, B; Petri-Fink, A

2014-07-01

65

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

66

Magnetic order of Fe3O4 Nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetite (Fe3O4) nanoparticles tend to self-assemble when they are deposited on a substrate and form a film. Our goal is to understand the magnetic order and magnetic interactions between the particles, when they are self-assembled. After bulk structural and magnetic characterizations previously presented, we have been studying our Fe3O4 nanoparticles by using soft X-ray Resonant Magnetic Scattering (XRMS) at synchrotron radiation facilities. This technique utilizes the interaction between magnetic spins and polarized light. [1] The resulting scattering patterns contain information about the magnetic order and magnetic fluctuations in the nanoparticles assembly. By studying the profile of the XRMS patterns, we try to extract the magnetic signal from the charge signal, and learn about the magnetic order between the nanoparticles. We also utilize the coherence of the X-ray light and apply a correlation spectroscopy technique to learn about magnetic fluctuations.

Cai, Yanping; Chesnel, Karine; Trevino, Matea; Westover, Andrew; Safsten, Alex; Harrison, Roger; Scherz, Andreas

2012-10-01

67

Ac magnetic susceptibility study of in vivo nanoparticle biodistribution  

NASA Astrophysics Data System (ADS)

We analysed magnetic nanoparticle biodistribution, before and after cytokine conjugation, in a mouse model by ac susceptibility measurements of the corresponding resected tissues. Mice received repeated intravenous injections of nanoparticle suspension for two weeks and they were euthanized 1 h after the last injection. In general, only 10% of the total injected nanoparticles after multiple exposures were found in tissues. The rest of the particles may probably be metabolized or excreted by the organism. Our findings indicate that the adsorption of interferon to DMSA-coated magnetic nanoparticles changes their biodistribution, reducing the presence of nanoparticles in lungs and therefore their possible toxicity. The specific targeting of the particles to tumour tissues by the use of an external magnetic field has also been studied. Magnetic nanoparticles were observed by transmission electron microscopy in the targeted tissue and quantified by ac magnetic susceptibility.

Gutiérrez, L.; Mejías, R.; Barber, D. F.; Veintemillas-Verdaguer, S.; Serna, C. J.; Lázaro, F. J.; Morales, M. P.

2011-06-01

68

Magnetic nanoparticle biodistribution following intratumoral administration  

NASA Astrophysics Data System (ADS)

Recently, heat generated by iron oxide nanoparticles (IONPs) stimulated by an alternating magnetic field (AMF) has shown promise in the treatment of cancer. To determine the mechanism of nanoparticle-induced cytotoxicity, the physical association of the cancer cells and the nanoparticles must be determined. We have used transmission electron microscopy (TEM) to define the time dependent cellular uptake of intratumorally administered dextran-coated, core-shell configuration IONP having a mean hydrodynamic diameter of 100-130 nm in a murine breast adenocarcinoma cell line (MTG-B) in vivo. Tumors averaging volumes of 115 mm3 were injected with iron oxide nanoparticles. The tumors were then excised and fixed for TEM at time 0.1-120 h post-IONP injection. Intracellular uptake of IONPs was 5.0, 48.8 and 91.1% uptake at one, 2 and 4 h post-injection of IONPs, respectively. This information is essential for the effective use of IONP hyperthermia in cancer treatment.

Giustini, A. J.; Ivkov, R.; Hoopes, P. J.

2011-08-01

69

Magnetic nanoparticle biodistribution following intratumoral administration.  

PubMed

Recently, heat generated by iron oxide nanoparticles (IONPs) stimulated by an alternating magnetic field (AMF) has shown promise in the treatment of cancer. To determine the mechanism of nanoparticle-induced cytotoxicity, the physical association of the cancer cells and the nanoparticles must be determined. We have used transmission electron microscopy (TEM) to define the time dependent cellular uptake of intratumorally administered dextran-coated, core-shell configuration IONP having a mean hydrodynamic diameter of 100-130 nm in a murine breast adenocarcinoma cell line (MTG-B) in vivo. Tumors averaging volumes of 115 mm3 were injected with iron oxide nanoparticles. The tumors were then excised and fixed for TEM at time 0.1-120 h post-IONP injection. Intracellular uptake of IONPs was 5.0, 48.8 and 91.1% uptake at one, 2 and 4 h post-injection of IONPs, respectively. This information is essential for the effective use of IONP hyperthermia in cancer treatment. PMID:21795772

Giustini, A J; Ivkov, R; Hoopes, P J

2011-08-26

70

Protein detection with magnetic nanoparticles in a rotating magnetic field  

NASA Astrophysics Data System (ADS)

A detection scheme based on magnetic nanoparticle (MNP) dynamics in a rotating magnetic field for a quantitative and easy-to-perform detection of proteins is illustrated. For the measurements, a fluxgate-based setup was applied, which measures the MNP dynamics, while a rotating magnetic field is generated. The MNPs exhibit single iron oxide cores of 25 nm and 40 nm diameter, respectively, as well as a protein G functionalized shell. IgG antibodies were utilized as binding target molecules for the physical proof-of-concept. The measurement results were fitted with a theoretical model describing the magnetization dynamics in a rotating magnetic field. The established detection scheme allows quantitative determination of proteins even at a concentration lower than of the particles. The observed differences between the two MNP types are discussed on the basis of logistic functions.

Dieckhoff, Jan; Lak, Aidin; Schilling, Meinhard; Ludwig, Frank

2014-01-01

71

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.

72

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. PMID:25382864

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

2014-01-01

73

LYSIS OF ANTIBODY COATED CHICKEN ERYTHROCYTES BY A NON-LYMPHOCYTE PIG BLOOD LEUKOCYTE  

E-print Network

LYSIS OF ANTIBODY COATED CHICKEN ERYTHROCYTES BY A NON-LYMPHOCYTE PIG BLOOD LEUKOCYTE B. CHARLEY H : minimal essential medium. CRBC : chicken red blood cells. PBL : peripheral blood leukocytes. EA communication, using a con- ventionnal slchromium release test with label- led chicken erythrocytes sensitized

Paris-Sud XI, Université de

74

Magnetic particle hyperthermia: nanoparticle magnetism and materials development for cancer therapy  

Microsoft Academic Search

Loss processes in magnetic nanoparticles are discussed with respect to optimization of the specific loss power (SLP) for application in tumour hyperthermia. Several types of magnetic iron oxide nanoparticles representative for different preparation methods (wet chemical precipitation, grinding, bacterial synthesis, magnetic size fractionation) are the subject of a comparative study of structural and magnetic properties. Since the specific loss power

Rudolf Hergt; Silvio Dutz; Robert Müller; Matthias Zeisberger

2006-01-01

75

Facile synthesis of magnetic iron oxide nanoparticles and their characterization  

NASA Astrophysics Data System (ADS)

Magnetic iron oxide nanoparticles are synthesized by suitable modification of the standard synthetic procedure without use of inert atmosphere and at room temperature. The facile synthesis procedure can be easily scaled up and is of important from industrial point of view for the commercial large scale production of magnetic iron oxide nanoparticles. The synthesized nanoparticles were characterized by thermal, dynamic light scattering, scanning electron microscopy and transmission electron microscopy analyses.

Jadhav, Sushilkumar A.; Patil, Suresh V.

2014-06-01

76

SIZE-OPTIMIZED MAGNETITE NANOPARTICLES FOR MAGNETIC PARTICLE IMAGING  

SciTech Connect

We present experimental results to demonstrate that there is an optimum size for magnetite nanoparticles that are used to generate MPI signal, where the signal is detected as the third harmonic of nanoparticle magnetization, M, for any driving field frequency, ?. Our experimental results, for an arbitrarily chosen ? = 250 kHz, agree with predictions for a nanoparticle magnetization model based on the Langevin theory of superparamagnetism.

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

2010-06-01

77

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

78

Dielectrophoresis-magnetophoresis force driven magnetic nanoparticle movement in transformer oil based magnetic fluids.  

PubMed

Magnetic fluid is a stable colloidal mixture contained magnetic nanoparticles coated with a surfactant. Recently, it was found that the fluid has properties to increase heat transfer and dielectric characteristics due to the added magnetic nanoparticles in transformer oils. The magnetic nanoparticles in the fluid experience an electrical force directed toward the place of maximum electric field strength when the electric field is applied. And when the external magnetic field is applied, the magnetic nanoparticles form long chains oriented along the direction of the field. The behaviors of magnetic nanoparticles in both the fields must play an important role in changing the heat transfer and dielectric characteristics of the fluids. In this study, we visualized the movement of magnetic nanoparticles influenced by both the fields applied in-situ. It was found that the magnetic nanoparticles travel in the region near the electrode by the electric field and form long chains along the field direction by the magnetic field. It can be inferred that the movement of magnetic nanoparticles appears by both the fields, and the breakdown voltage of transformer oil based magnetic fluids might be influenced according to the dispersion of magnetic nanoparticles. PMID:24205624

Lee, Jong-Chul; Lee, Sangyoup

2013-09-01

79

Surface modification of magnetic nanoparticles in biomedicine  

NASA Astrophysics Data System (ADS)

Progress in surface modification of magnetic nanoparticles (MNPs) is summarized with regard to organic molecules, macromolecules and inorganic materials. Many researchers are now devoted to synthesizing new types of multi-functional MNPs, which show great application potential in both diagnosis and treatment of disease. By employing an ever-greater variety of surface modification techniques, MNPs can satisfy more and more of the demands of medical practice in areas like magnetic resonance imaging (MRI), fluorescent marking, cell targeting, and drug delivery. Project supported by the National Natural Science Foundation of China (Grant Nos. 51125001 and 51172005), the Natural Science Foundation of Beijing,China (Grant No. 2122022), the Science Fund for Creative Research Groups of the National Natural Science Foundation of China (Grant No. 81421004), and the Doctoral Program of the Education Ministry of China (Grant No. 20120001110078).

Chu, Xin; Yu, Jing; Hou, Yang-Long

2015-01-01

80

Magnetically multiplexed heating of single domain nanoparticles  

NASA Astrophysics Data System (ADS)

Selective hysteretic heating of multiple collocated types of single domain magnetic nanoparticles (SDMNPs) by alternating magnetic fields (AMFs) may offer a useful tool for biomedical applications. The possibility of "magnetothermal multiplexing" has not yet been realized, in part due to prevalent use of linear response theory to model SDMNP heating in AMFs. Dynamic hysteresis modeling suggests that specific driving conditions play an underappreciated role in determining optimal material selection strategies for high heat dissipation. Motivated by this observation, magnetothermal multiplexing is theoretically predicted and empirically demonstrated by selecting SDMNPs with properties that suggest optimal hysteretic heat dissipation at dissimilar AMF driving conditions. This form of multiplexing could effectively offer multiple channels for minimally invasive biological signaling applications.

Christiansen, M. G.; Senko, A. W.; Chen, R.; Romero, G.; Anikeeva, P.

2014-05-01

81

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

82

Nonlinear susceptibility magnitude imaging of magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

This study demonstrates a method for improving the resolution of susceptibility magnitude imaging (SMI) using spatial information that arises from the nonlinear magnetization characteristics of magnetic nanoparticles (mNPs). In this proof-of-concept study of nonlinear SMI, a pair of drive coils and several permanent magnets generate applied magnetic fields and a coil is used as a magnetic field sensor. Sinusoidal alternating current (AC) in the drive coils results in linear mNP magnetization responses at primary frequencies, and nonlinear responses at harmonic frequencies and intermodulation frequencies. The spatial information content of the nonlinear responses is evaluated by reconstructing tomographic images with sequentially increasing voxel counts using the combined linear and nonlinear data. Using the linear data alone it is not possible to accurately reconstruct more than 2 voxels with a pair of drive coils and a single sensor. However, nonlinear SMI is found to accurately reconstruct 12 voxels (R2=0.99, CNR=84.9) using the same physical configuration. Several time-multiplexing methods are then explored to determine if additional spatial information can be obtained by varying the amplitude, phase and frequency of the applied magnetic fields from the two drive coils. Asynchronous phase modulation, amplitude modulation, intermodulation phase modulation, and frequency modulation all resulted in accurate reconstruction of 6 voxels (R2>0.9) indicating that time multiplexing is a valid approach to further increase the resolution of nonlinear SMI. The spatial information content of nonlinear mNP responses and the potential for resolution enhancement with time multiplexing demonstrate the concept and advantages of nonlinear SMI.

Ficko, Bradley W.; Giacometti, Paolo; Diamond, Solomon G.

2015-03-01

83

Magnetic nanoparticle assembly arrays prepared by hierarchical self-assembly on a patterned surface.  

PubMed

Inverted pyramid hole arrays were fabricated by photolithography and used as templates to direct the growth of colloidal nanoparticle assemblies. Cobalt ferrite nanoparticles deposit in the holes to yield high quality pyramid magnetic nanoparticle assembly arrays by carefully controlling the evaporation of the carrier fluid. Magnetic measurements indicate that the pyramid magnetic nanoparticle assembly arrays preferentially magnetize perpendicular to the substrate. PMID:25712606

Wen, Tianlong; Zhang, Dainan; Wen, Qiye; Zhang, Huaiwu; Liao, Yulong; Li, Qiang; Yang, Qinghui; Bai, Feiming; Zhong, Zhiyong

2015-03-01

84

Magnetic nanoparticles coated with polysaccharide polymers for potential biomedical applications  

Microsoft Academic Search

This study reports a two-steps route for obtaining magnetic nanoparticles–polysaccharide hybrid materials consisting of Fe3O4, NiFe2O4 and CuFe2O4 nanoparticles synthesis by coprecipitation method in the presence of a soft template followed by coating of ferrite nanoparticles\\u000a of 8–10-nm size range with polysaccharide type polymers—sodium alginate or chitosan. Magnetic oxide nanoparticles and the\\u000a corresponding hybrid materials were characterized by X-ray diffraction

Cristina Ileana Covaliu; Daniela Berger; Cristian Matei; Lucian Diamandescu; Eugeniu Vasile; Camelia Cristea; Valentin Ionita; Horia Iovu

85

Optimizing colloidal dispersity of magnetic nanoparticles based on magnetic separation with magnetic nanowires array  

NASA Astrophysics Data System (ADS)

Based on sharp geometry of Ni nanowires, we developed a novel high-gradient magnetic separator that was composed of a nanowires array and a uniform magnetic field. When suspension of magnetic nanoparticles (MNPs) flowed through it, the relatively large nanoparticles or clusters were removed from the suspension so that the size distribution can be improved. The separation resulted from magnetic force so that extra molecules or solvents were unnecessary to add. The performance was proved by scanned electron microscopy characterization and dynamic light scattering measurement. The improvement in magnetic colloidal dispersivity is important for the biomedical application of MNPs. Our results may also play a role in microfluidic application and nanoparticle-based detection.

Sun, Jianfei; He, Miaomiao; Liu, Xuan; Gu, Ning

2015-02-01

86

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

87

Complex magnetic reversal modes in low-symmetry nanoparticles  

NASA Astrophysics Data System (ADS)

A detailed numerical analysis of the magnetization reversal processes in T-shaped nanoparticles has been carried out. Attention has been focused on the influence of the symmetry of the particle on the formation, propagation, and interaction of internal magnetic structures such as domain walls, vortices, and antivortices. Results show that the lower the degree of symmetry of the particle, the more complex the reversal process is. Thus, symmetry represents an additional ingredient to control the magnetic properties of ferromagnetic nanoparticles.

Escobar, R. A.; Vargas, N. M.; Castillo-Sepúlveda, S.; Allende, S.; Altbir, D.; d'Albuquerque e Castro, J.

2014-03-01

88

Biomedical and environmental applications of magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

This paper presents an overview of syntheses and applications of magnetic nanoparticles (MNPs) at the Institute of Materials Science, Vietnam Academy of Science and Technology. Three families of oxide MNPs, magnetite, manganite and spinel ferrite materials, were prepared in various ways: coprecipitation, sol–gel and high energy mechanical milling. Basic properties of MNPs were characterized by Vibrating Sample Magnetometer (VSM) and Physical Properties Measurement Systems (PPMS). As for biomedical application, the aim was to design a novel multifunctional, nanosized magnetofluorescent water-dispersible Fe3O4-curcumin conjugate, and its ability to label, target and treat tumor cells was described. The conjugate possesses a magnetic nano Fe3O4 core, chitosan (CS) or Oleic acid (OL) as an outer shell and entrapped curcumin (Cur), serving the dual function of naturally autofluorescent dye as well as antitumor model drug. Fe3O4-Cur conjugate exhibited a high loading cellular uptake with the help of a macrophage, which was clearly visualized dually by Fluorescence Microscope and Laser Scanning Confocal Microscope (LSCM), as well as by magnetization measurement (PPMS). A preliminary magnetic resonance imaging (MRI) study also showed a clear contrast enhancement by using the conjugate. As for the environmental aspect, the use of magnetite MNPs for the removal of heavy toxic metals, such as Arsenic (As) and Lead (Pb), from contaminated water was studied.

Tran, Dai Lam; Le, Van Hong; Linh Pham, Hoai; Nhung Hoang, Thi My; Quy Nguyen, Thi; Luong, Thien Tai; Thu Ha, Phuong; Phuc Nguyen, Xuan

2010-12-01

89

Quadrupole magnetic field-flow fractionation for the analysis of magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Field-flow fractionation (FFF) is an analytical scale separation and characterizatio technique for macromolecules and particles. A quadrupole magnetic FFF device has bee constructed for analyzing magnetic nanoparticles. It is shown to give reproducible results and be capable of distinguishing between different lots of a commercial magnetic nanoparticle material.

Carpino, Francesca; Moore, Lee R.; Chalmers, Jeffrey J.; Zborowski, Maciej; Williams, P. Stephen

2005-01-01

90

Nanomedicine: magnetic nanoparticles and their biomedical applications.  

PubMed

During this past decade, science and engineering have seen a rapid increase in interest for nanoscale materials with dimensions less than 100 nm, which lie in the intermediate state between atoms and bulk (solid) materials. Their attributes are significantly altered relative to the corresponding bulk materials as they exhibit size dependent behavior such as quantum size effects (depending on bulk Bohr radius), optical absorption and emission, coulomb staircase behavior (electrical transport), superparamagnetism and various unique properties. They are active components of ferrofluids, recording tape, flexible disk recording media along with potential future applications in spintronics: a new paradigm of electronics utilizing intrinsic charge and spin of electrons for ultra-high-density data storage and quantum computing. They are used in a gamut of biomedical applications: bioseparation of biological entities, therapeutic drugs and gene delivery, radiofrequency-induced destruction of cells and tumors (hyperthermia), and contrast-enhancement agents for magnetic resonance imaging (MRI). The magnetic nanoparticles have optimizable, controllable sizes enabling their comparison to cells (10-100 µm), viruses (20-250 nm), proteins (3-50 nm), and genes (10-100 nm). Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) provide necessary characterization methods that enable accurate structural and functional analysis of interaction of the biofunctional particles with the target bioentities. The goal of the present discussion is to provide a broad review of magnetic nanoparticle research with a special focus on the synthesis, functionalization and medical applications of these particles, which have been carried out during the past decade, and to examine several prospective directions. PMID:20629620

Banerjee, Reshmi; Katsenovich, Yelena; Lagos, Leonel; McIintosh, M; Zhang, Xueji; Li, Chen-Zhong

2010-01-01

91

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

92

Magnetic resonance nanoparticles for cardiovascular molecular imaging and therapy.  

PubMed

Molecular vascular imaging represents a novel tool that promises to change the current medical paradigm of 'see and treat' to a 'detect and prevent' strategy. Nanoparticle agents, such as superparamagnetic nanoparticles and perfluorocarbon nanoparticle emulsions, have been developed for noninvasive imaging, particularly for magnetic resonance imaging. Designed to target specific epitopes in tissues, these agents are beginning to enter clinical trials for cardiovascular applications. The delivery of local therapy with these nanoparticles, using mechanisms such as contact-facilitated drug delivery, is in the advanced stages of preclinical research. Ultimately, combined diagnostic and therapeutic nanoparticle formulations may allow patients to be characterized noninvasively and segmented to receive custom-tailored therapy. This review focuses on recent developments of nanoparticle technologies with an emphasis on cardiovascular applications of magnetic resonance imaging. PMID:16076280

Cyrus, Tillmann; Winter, Patrick M; Caruthers, Shelton D; Wickline, Samuel A; Lanza, Gregory M

2005-07-01

93

Assessing magnetic nanoparticle aggregation in polymer melts by dynamic magnetic susceptibility measurements  

NASA Astrophysics Data System (ADS)

Aggregation of magnetic nanoparticles in polymer melts was assessed using dynamic magnetic susceptibility measurements. Magnetic nanocomposites consisting of polybutadiene/CoFe2O4 and polystyrene/CoFe2O4 mixtures were prepared using different techniques and characterized using dynamic magnetic susceptibility measurements. The presence of nanoparticle aggregates determined using magnetic measurements was confirmed with transmission electron microscopy examinations. The results were in good agreement with predictions from the Flory-Huggins interaction parameters.

Sierra-Bermúdez, Sergio; Maldonado-Camargo, Lorena P.; Orange, François; Guinel, Maxime J.-F.; Rinaldi, Carlos

2015-03-01

94

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

2014-11-01

95

Effect of size distribution on metastability in magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles that have been synthesized using various methods have size distributions. This results in distributions in the magnetic anisotropy of magnetic nanoparticles. Considering the particle size distributions, we investigate metastability in magnetic nanoparticles at low temperatures. To model this system, we use a spin S=1 ferromagnetic Blume-Capel model on a square lattice with periodic boundary conditions. The particle size distribution is incorporated in the model such that the uniaxial magnetic anisotropy parameter has a Gaussian distribution. We perform kinetic Monte Carlo simulations of the Blume-Capel model with the Glauber dynamic to explore magnetization relaxation in the regime where a single droplet of flipped spins forms a critical droplet. We present the lifetime of the metastable state as a function of temperature and standard deviation of the magnetic anisotropy distribution as well as a finite-size effect on the lifetime.

Yamamoto, Yoh; Park, Kyungwha

2011-03-01

96

Magnetic Nanoparticles: Surface Effects and Properties Related to Biomedicine Applications  

PubMed Central

Due to finite size effects, such as the high surface-to-volume ratio and different crystal structures, magnetic nanoparticles are found to exhibit interesting and considerably different magnetic properties than those found in their corresponding bulk materials. These nanoparticles can be synthesized in several ways (e.g., chemical and physical) with controllable sizes enabling their comparison to biological organisms from cells (10–100 ?m), viruses, genes, down to proteins (3–50 nm). The optimization of the nanoparticles’ size, size distribution, agglomeration, coating, and shapes along with their unique magnetic properties prompted the application of nanoparticles of this type in diverse fields. Biomedicine is one of these fields where intensive research is currently being conducted. In this review, we will discuss the magnetic properties of nanoparticles which are directly related to their applications in biomedicine. We will focus mainly on surface effects and ferrite nanoparticles, and on one diagnostic application of magnetic nanoparticles as magnetic resonance imaging contrast agents. PMID:24232575

Issa, Bashar; Obaidat, Ihab M.; Albiss, Borhan A.; Haik, Yousef

2013-01-01

97

Magnetic nanoparticle-based cancer nanodiagnostics  

NASA Astrophysics Data System (ADS)

Diagnosis facilitates the discovery of an impending disease. A complete and accurate treatment of cancer depends heavily on its early medical diagnosis. Cancer, one of the most fatal diseases world-wide, consistently affects a larger number of patients each year. Magnetism, a physical property arising from the motion of electrical charges, which causes attraction and repulsion between objects and does not involve radiation, has been under intense investigation for several years. Magnetic materials show great promise in the application of image contrast enhancement to accurately image and diagnose cancer. Chelating gadolinium (Gd III) and magnetic nanoparticles (MNPs) have the prospect to pave the way for diagnosis, operative management, and adjuvant therapy of different kinds of cancers. The potential of MNP-based magnetic resonance (MR) contrast agents (CAs) now makes it possible to image portions of a tumor in parts of the body that would be unclear with the conventional magnetic resonance imaging (MRI). Multiple functionalities like variety of targeting ligands and image contrast enhancement have recently been added to the MNPs. Keeping aside the additional complexities in synthetic steps, costs, more convoluted behavior, and effects in-vivo, multifunctional MNPs still face great regulatory hurdles before clinical availability for cancer patients. The trade-off between additional functionality and complexity is a subject of ongoing debate. The recent progress regarding the types, design, synthesis, morphology, characterization, modification, and the in-vivo and in-vitro uses of different MRI contrast agents, including MNPs, to diagnose cancer will be the focus of this review. As our knowledge of MNPs' characteristics and applications expands, their role in the future management of cancer patients will become very important. Current hurdles are also discussed, along with future prospects of MNPs as the savior of cancer victims.

Zubair, Yousaf Muhammad; Yu, Jing; Hou, Yang-Long; Gao, Song

2013-05-01

98

Mass production of magnetic nickel nanoparticle in thermal plasma reactor  

SciTech Connect

We report the mass production of Ni metal nanoparticles using dc transferred arc thermal plasma reactor by homogeneous gas phase condensation process. To increase the evaporation rate and purity of Ni nanoparticles small amount of hydrogen added along with argon in the plasma. Crystal structure analysis was done by using X-ray diffraction technique. The morphology of as synthesized nanoparticles was carried out using FESEM images. The magnetic properties were measured by using vibrating sample magnetometer at room temperature.

Kanhe, Nilesh S.; Nawale, Ashok B.; Bhoraskar, S. V.; Mathe, V. L., E-mail: vlmathe@physics.unipune.ac.in [Department of Physics, University of Pune, Pune- 411007 (India); Das, A. K. [Laser and Plasma Technology Division, Bhabha Atomic Research Center, Trombay, Mumbai- 400085 (India)

2014-04-24

99

Mass production of magnetic nickel nanoparticle in thermal plasma reactor  

NASA Astrophysics Data System (ADS)

We report the mass production of Ni metal nanoparticles using dc transferred arc thermal plasma reactor by homogeneous gas phase condensation process. To increase the evaporation rate and purity of Ni nanoparticles small amount of hydrogen added along with argon in the plasma. Crystal structure analysis was done by using X-ray diffraction technique. The morphology of as synthesized nanoparticles was carried out using FESEM images. The magnetic properties were measured by using vibrating sample magnetometer at room temperature.

Kanhe, Nilesh S.; Nawale, Ashok B.; Bhoraskar, S. V.; Das, A. K.; Mathe, V. L.

2014-04-01

100

Surface charge switching nanoparticles for magnetic resonance imaging.  

PubMed

In this study, polypeptide-based nanoparticles [constituted using poly(L-lysine) coupled with deoxycholic acid (DOCA) and conjugated with 2,3-dimethylmaleic acid (DMA)] have high tumor selectivity once electrostatically switched by the acidic milieu of solid tumors. These nanoparticles exhibited a significantly increased in vitro cellular uptake and high accumulation in the acidic tumor site in vivo. Consequently, Fe3O4-loaded nanoparticles enabled high contrast magnetic resonance (MR) imaging of the tumor in vivo. PMID:24858382

Lee, Dong Jin; Oh, Young Taik; Lee, Eun Seong

2014-08-25

101

The role of cobalt ferrite magnetic nanoparticles in medical science.  

PubMed

The nanotechnology industry is rapidly growing and promises that the substantial changes that will have significant economic and scientific impacts be applicable to a wide range of areas, such as aerospace engineering, nano-electronics, environmental remediation and medical healthcare. In this area, cobalt ferrite nanoparticles have been regarded as one of the competitive candidates because of their suitable physical, chemical and magnetic properties like the high anisotropy constant, high coercivity and high Curie temperature, moderate saturation magnetization and ease of synthesis. This paper introduces the magnetic properties, synthesis methods and some medical applications, including the hyperthermia, magnetic resonance imaging (MRI), magnetic separation and drug delivery of cobalt ferrite nanoparticles. PMID:25428034

Amiri, S; Shokrollahi, H

2013-01-01

102

Multifunctional magnetic and fluorescent core-shell nanoparticles for bioimaging.  

PubMed

Novel magnetic and fluorescent core-shell nanoparticles have been fabricated, which exhibit superparamagnetic behavior and emit strong near-infrared fluorescence. The nanoparticles are highly biocompatible and can be internalized into cells with nucleic accumulation via strong interaction with nucleic acids, implying potential applications in the biomedical field. PMID:25515132

Lu, Yanjiao; He, Bicheng; Shen, Jie; Li, Jie; Yang, Wantai; Yin, Meizhen

2015-01-22

103

Labeling of macrophage cell using biocompatible magnetic nanoparticles  

Microsoft Academic Search

This work investigates the intrinsic cell labeling efficiency of the Fe3O4 nanoparticles prepared by a modified thermal decomposition method using nontoxic precursors and a biocompatible polymer surfactant. This method eliminates the current need for additional step of surface modification. The structural analysis reveals the highly crystalline feature of the nanoparticles, while the magnetic measurement shows their superparamagnetic behavior at room

Ji Hyun Min; Sung Tae Kim; Ji Sung Lee; Kwanghee Kim; Jun Hua Wu; Jaeho Jeong; Ah Young Song; Kyung-Mi Lee; Young Keun Kim

2011-01-01

104

Progress in applications of magnetic nanoparticles in biomedicine  

Microsoft Academic Search

A progress report is presented on a selection of scientific, technological and commercial advances in the biomedical applications of magnetic nanoparticles since 2003. Particular attention is paid to (i) magnetic actuation for in vitro non-viral transfection and tissue engineering and in vivo drug delivery and gene therapy, (ii) recent clinical results for magnetic hyperthermia treatments of brain and prostate cancer

Q A Pankhurst; NKT Thanh; J Dobson

2009-01-01

105

The quantitative measurement of magnetic moments from phase images of nanoparticles and nanostructures--I. Fundamentals  

E-print Network

The quantitative measurement of magnetic moments from phase images of nanoparticles: Electron holography Phase shift Magnetic nanoparticles Magnetic moment a b s t r a c t An approach that can be used to measure the magnetic moment of a magnetized nanoparticle or nanostructure from an electron

Dunin-Borkowski, Rafal E.

106

Magnetic nanoparticles for bio-analytical applications  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles are widely being used in various fields of medicine, biology and separations. This dissertation focuses on the synthesis and use of magnetic nanoparticles for targeted drug delivery and analytical separations. The goals of this research include synthesis of biocompatible surface modified monodisperse superparamagnetic iron oxide nanoparticles (SPIONs) by novel techniques for targeted drug delivery and use of SPIONs as analytical sensing tools. Surface modification of SPIONs was performed with two different co-polymers: tri block co-polymer Pluronics and octylamine modified polyacrylic acid. Samples of SPIONs were subsequently modified with 4 different commercially available, FDA approved tri-block copolymers (Pluronics), covering a wide range of molecular weights (5.75-14.6 kDa). A novel, technically simpler and faster phase transfer approach was developed to surface modify the SPIONs with Pluronics for drug delivery and other biomedical applications. The hydrodynamic diameter and aggregation properties of the Pluronic modified SPIONs were studied by dynamic light scattering (DLS). The coverage of SPIONs with Pluronics was supported with IR Spectroscopy and characterized by Thermo gravimetric Analysis (TGA). The drug entrapment capacity of SPIONs was studied by UV-VIS spectroscopy using a hydrophobic carbocyanine dye, which serves as a model for hydrophobic drugs. These studies resulted in a comparison of physical properties and their implications for drug loading capacities of the four types of Pluronic coated SPIONs for drug delivery assessment. These drug delivery systems could be used for passive drug targeting. However, Pluronics lack the functional group necessary for bioconjugation and hence cannot achieve active targeting. SPIONs were functionalized with octylamine modified polyacrylic acid-based copolymer, providing water solubility and facile biomolecular conjugation. Epirubicin was loaded onto SPIONs and the drug entrapment was studied by UVVIS spectrophotometry. In this study, the antisense oligonucleotide sequence to the anti-apoptopic protein survivin was coupled to SPIONs to provide molecular targeting and potential therapy for cancer cells. Successful coupling of antisense survivin to SPIONs was demonstrated by circular dichroism studies of the conjugate and its complementary sequence. Such multifunctional SPIONs can be used as active targeting agents for cancer cells, producing enhanced magnetic resonance imaging contrast and releasing chemotherapeutic agents to targeted cells. SPIONs also serve as an excellent platform for analytical sensing. Streptavidin modified SPIONs were used as substrates to immobilize biotinylated aptamers (single-stranded DNA). The binding affinity of such aptamers to its target was achieved by quantifying the amount of target released from the aptamer. This quantification was achieved using pH-mediated stacking capillary electrophoresis. SPIONs were shown to be more efficient compared to magnetic microbeads as the sensing elements. The binding affinity constant of the aptamer determined was almost 8-fold better than that obtained using magnetic microbeads.

Yedlapalli, Sri Lakshmi

107

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

108

Temperature of the Magnetic Nanoparticle Microenvironment: Estimation from Relaxation Times  

PubMed Central

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, IM; Reeves, DB; Zhang, X; Kuehlert, E; Forauer, ER; Weaver, JB

2014-01-01

109

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

110

Optimal Halbach permanent magnet designs for maximally pulling and pushing nanoparticles  

E-print Network

Optimal Halbach permanent magnet designs for maximally pulling and pushing nanoparticles A. Sarwar targeting Optimal permanent magnet Nano-particle trapping Pushing nanoparticle Halbach array design a b to focus therapeutic nanoparticles to disease locations, the sharp fall off of magnetic fields and forces

Shapiro, Benjamin

111

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

112

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

E-print Network

1 Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields nanoclusters (of a mean diameter of 60 nm) was pushed through a thin slit channel with the nickel microspheres

Paris-Sud XI, Université de

113

Controlling transport and chemical functionality of magnetic nanoparticles.  

PubMed

A wide range of metal, magnetic, semiconductor, and polymer nanoparticles with tunable sizes and properties can be synthesized by wet-chemical techniques. Magnetic nanoparticles are particularly attractive because their inherent superparamagnetic properties make them desirable for medical imaging, magnetic field assisted transport, and separations and analyses. With such applications on the horizon, synthetic routes for quickly and reliably rendering magnetic nanoparticle surfaces chemically functional have become an increasingly important focus. This Account describes common synthetic routes for making and functionalizing magnetic nanoparticles and discusses initial applications in magnetic field induced separations. The most widely studied magnetic nanoparticles are iron oxide (Fe2O3 and Fe3O4), cobalt ferrite (CoFe 2O4), iron platinum (FePt), and manganese ferrite (MnFe 2O4), although others have been investigated. Magnetic nanoparticles are typically prepared under either high-temperature organic phase or aqueous conditions, producing particles with surfaces that are stabilized by attached surfactants or associated ions. Although it requires more specialized glassware, high-temperature routes are generally preferred when a high degree of stability and low particle size dispersity is desired. Particles can be further modified with a secondary metal or polymer to create core-shell structures. The outer shells function as protective layers for the inner metal cores and alter the surface chemistry to enable postsynthetic modification of the surfactant chemistry. Efforts by our group as well as others have centered on pathways to yield nanoparticles with surfaces that are both easily functionalized and tunable in terms of the number and variety of attached species. Ligand place-exchange reactions have been shown quite successful for exchanging silanes, acids, thiols, and dopamine ligands onto the surfaces of some magnetic particles. Poly(ethylene oxide)-modified phospholipids can be inserted into nonpolar surface monolayers of as-prepared nanoparticles as a method for modifying the surface chemistry that induces water solubility. In general, reactive termini can subsequently be used to append a range of chemical groups. For example, surfactants with trifluoroethylester or azide termini have been used to attach a range of amine- or alkyne-containing species, respectively. Chemically functionalized magnetic nanoparticles are promising as advanced materials for analytical separations and analysis. Magnetic field flow fractionation leverages the size-dependent magnetic moments to purify and separate the components of a complex mixture of particles. Similarly, magnetic field gradients are useful for manipulating transport and separation in simple microfluidic devices. By either approach, magnet-induced transport of the particles is a simple method in which an attached reagent, catalyst, or bioanalytical tag can be moved between flow streams within a lab on a chip device. PMID:18251514

Latham, Andrew H; Williams, Mary Elizabeth

2008-03-01

114

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

115

Magnetic structures of 2D and 3D nanoparticles  

NASA Astrophysics Data System (ADS)

The minimization of exchange interactions and dipolar interactions in 2D and 3D nanoparticles is obtained from a powerful variational approach of the local spin Hamiltonian and leads to a different set of equations which correspond to different levels of screening of the long range dipolar interactions. These equations are shown to introduce topological defects which are analyzed on the basis of elementary spin clusters. Four basic topological defects are deduced for 2D nanoparticles, as observed in magnetic samples and simulations and 10 basic topological defects are deduced for 3D nanoparticles. These singularities induce complex variations of magnetization around them and non-linear properties.

Levy, J.-C. S.

2015-01-01

116

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

117

Design and Application of Magnetic-based Theranostic Nanoparticle Systems  

PubMed Central

Recently, magnetic-based theranostic nanoparticle (MBTN) systems have been studied, researched, and applied extensively to detect and treat various diseases including cancer. Theranostic nanoparticles are advantageous in that the diagnosis and treatment of a disease can be performed in a single setting using combinational strategies of targeting, imaging, and/or therapy. Of these theranostic strategies, magnetic-based systems containing magnetic nanoparticles (MNPs) have gained popularity because of their unique ability to be used in magnetic resonance imaging, magnetic targeting, hyperthermia, and controlled drug release. To increase their effectiveness, MNPs have been decorated with a wide variety of materials to improve their biocompatibility, carry therapeutic payloads, encapsulate/bind imaging agents, and provide functional groups for conjugation of biomolecules that provide receptor-mediated targeting of the disease. This review summarizes recent patents involving various polymer coatings, imaging agents, therapeutic agents, targeting mechanisms, and applications along with the major requirements and challenges faced in using MBTN for disease management. PMID:23795343

Wadajkar, Aniket S.; Menon, Jyothi U.; Kadapure, Tejaswi; Tran, Richard T.; Yang, Jian; Nguyen, Kytai T.

2013-01-01

118

Labeling of macrophage cell using biocompatible magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

This work investigates the intrinsic cell labeling efficiency of the Fe3O4 nanoparticles prepared by a modified thermal decomposition method using nontoxic precursors and a biocompatible polymer surfactant. This method eliminates the current need for additional step of surface modification. The structural analysis reveals the highly crystalline feature of the nanoparticles, while the magnetic measurement shows their superparamagnetic behavior at room temperature. Fe3O4 nanoparticles were efficiently incorporated into the murine macrophage cells (RAW264.7) without visible cytotoxicity. Cell labeling efficiency was found to be over 90% as measured by magnetically activated cell sorting and physical property measurement system. Therefore, such Fe3O4 nanoparticles could provide a useful magnetic cell labeling tool for macrophage cells using their phagocytic/endocytic activity and further apply to the other relevant biomedical applications.

Min, Ji Hyun; Kim, Sung Tae; Lee, Ji Sung; Kim, Kwanghee; Wu, Jun Hua; Jeong, Jaeho; Song, Ah Young; Lee, Kyung-Mi; Kim, Young Keun

2011-04-01

119

Magnetic nanoparticles for medical applications: Progress and challenges  

SciTech Connect

Magnetic nanoparticles present unique properties that make them suitable for applications in biomedical field such as magnetic resonance imaging (MRI), hyperthermia and drug delivery systems. Magnetic hyperthermia involves heating the cancer cells by using magnetic particles exposed to an alternating magnetic field. The cell temperature increases due to the thermal propagation of the heat induced by the nanoparticles into the affected region. In order to increase the effectiveness of the treatment hyperthermia can be combined with drug delivery techniques. As a spectroscopic technique MRI is used in medicine for the imaging of tissues especially the soft ones and diagnosing malignant or benign tumors. For this purpose Zn{sub x}Co{sub 1?x}Fe{sub 2}O{sub 4} ferrite nanoparticles with x between 0 and 1 have been prepared by co-precipitation method. The cristallite size was determined by X-ray diffraction, while the transmission electron microscopy illustrates the spherical shape of the nanoparticles. Magnetic characterizations of the nanoparticles were carried out at room temperature by using a vibrating sample magnetometer. The specific absorption rate (SAR) was measured by calorimetric method at different frequencies and it has been observed that this value depends on the chemical formula, the applied magnetic fields and the frequency. The study consists of evaluating the images, obtained from an MRI facility, when the nanoparticles are dispersed in agar phantoms compared with the enhanced ones when Omniscan was used as contrast agent. Layer-by-layer technique was used to achieve the necessary requirement of biocompatibility. The surface of the magnetic nanoparticles was modified by coating it with oppositely charged polyelectrolites, making it possible for the binding of a specific drug.

Doaga, A.; Cojocariu, A. M.; Constantin, C. P.; Caltun, O. F. [Faculty of Physics, Alexandru Ioan Cuza University, Bd. Carol I. Nr. 11, Iasi, 700506 (Romania); Hempelmann, R. [Physical Chemistry Department, Saarland University, 66123 Saarbrücken (Germany)

2013-11-13

120

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

121

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

122

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

123

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

124

Biocompatible core-shell magnetic nanoparticles for cancer treatment  

SciTech Connect

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

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

2008-04-01

125

Biocompatible core-shell magnetic nanoparticles for cancer treatment  

NASA Astrophysics Data System (ADS)

Nontoxic magnetic nanoparticles (MNPs) have expanded treatment delivery options in the medical world. With a size range from 2to200nm, MNPs can be compiled with most of the small cells and tissues in the living body. Monodispersive iron-iron oxide core-shell nanoparticles were prepared by our novel cluster deposition system. This unique method of preparing core-shell MNPs gives the nanoparticles a very high magnetic moment. We tested the nontoxicity and uptake of MNPs coated with/without dextrin by incubating them with rat LX-1 small cell lung cancer cells. Since core iron enhances the heating effect [L. Baker, Q. Zeing, W. Li, and S. Sullivan, J. Appl. Phys. 99, 08H106 (2006)], the rate of oxidation of iron nanoparticles was also tested in de-ionized water at a certain time interval. Both coated and noncoated MNPs were successfully uptaken by the cells, indicating that the nanoparticles were not toxic. The stability of MNPs was verified by x-ray diffraction scan after 0, 24, 48, 96, and 204h. Due to the high magnetic moment offered by MNPs produced in our laboratory, we predict that even at low applied external alternating field, the desired temperature could be reached in cancer cells in comparison to the commercially available nanoparticles. Moreover our MNPs do not require additional transfection agent, providing a cost effective means of treatment with significantly lower dosage in the body in comparison to commercially available nanoparticles.

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

2008-04-01

126

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

E-print Network

Paris 13, 93017 Bobigny, France. The magnetic properties of densely packed magnetic nanoparticles (MNP properties [7]. A complete understanding of the macroscopic magnetic properties of MNP assemblies in terms parameters of the distribution and MNP properties from the magnetic measurements. Two key features which

Boyer, Edmond

127

Magnetically textured -Fe2O3 nanoparticles in a silica gel matrix: Structural and magnetic properties  

E-print Network

Magnetically textured -Fe2O3 nanoparticles in a silica gel matrix: Structural and magnetic the solidification of the matrix on the in-field magnetization process, is studied by alternating gradient force November 1997; accepted for publication 11 March 1998 This paper is devoted to magnetic and structural

Paris-Sud XI, Université de

128

Millimeter Scale Alignment of Magnetic Nanoparticle Functionalized Microtubules in Magnetic Fields  

E-print Network

techniques,4 by viscous forces,5 or by strong magnetic or electric fields applied during tubule-modified microtubules, this cell was placed on top of a NdFeB permanent magnet for 3-10 min and visualized usingMillimeter Scale Alignment of Magnetic Nanoparticle Functionalized Microtubules in Magnetic Fields

Hancock, William O.

129

Interface charge transfer in polypyrrole coated perovskite manganite magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Different hybrid structures were obtained by coating magnetic nanoparticles of perovskite type manganite at optimal doping (La0.67Sr0.33MnO3,LSMO) with different quantities of polypyrrole (PPy). The amorphous layer of polypyrrole surrounding the crystalline magnetic core was observed by high resolution transmission electron microscopy (HRTEM) and analyzed by using X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) measurements in near edge structure (XANES) techniques. By analyzing the magnetic behavior of the samples one can observe that the surface modification of magnetic nanoparticles by PPy results in an increase in the saturation magnetization of the composites. The process is ascribed to paired electrons transferred from the delocalized ? states of the PPy into the outer disordered layers of the manganite. The analysis of pre-edge peak of the Mn K-edge XANES spectra in the case of PPy coated LSMO nanoparticles indicates that the charge transfer between polymer and nanoparticles is (directed) going to missing or distorted oxygen positions, hence increasing the 3d electrons' mobility and orbital hybridization between the neighboring manganese ion. As a consequence, within the surface layers of LSMO nanoparticles, both energy bands disrupted the structure, and the double exchange process between Mn ions was reestablished determining the saturation magnetizations and pre-edge features increase, respectively.

Pana, O.; Soran, M. L.; Leostean, C.; Macavei, S.; Gautron, E.; Teodorescu, C. M.; Gheorghe, N.; Chauvet, O.

2012-02-01

130

Synthesis and Characterization of Polymer-Templated Magnetic Nanoparticles  

NASA Astrophysics Data System (ADS)

This research reports on the investigation into the synthesis and stabilization of iron oxide nanoparticles for theranostic applications using amine-epoxide polymers. Although theranostic agents such as magnetic nanoparticles have been designed and developed for a few decades, there is still more work that needs to be done with the type of materials that can be used to stabilize or functionalize these particles if they are to be used for applications such as drug delivery, imaging and hyperthermia. For in-vivo applications, it is crucial that organic coatings enclose the nanoparticles in order to prevent aggregation and facilitate efficient removal from the body as well as protect the body from toxic material. The objective of this thesis is to design polymer coated magnetite nanoparticles with polymers that are biocompatible and can stabilize the iron oxide nanoparticle to help create mono-dispersed particles in solution. It is desirable to also have these nanoparticles possess high magnetic susceptibility in response to an applied magnetic field. The co-precipitation method was selected because it is probably the simplest and most efficient chemical pathway to obtain magnetic nanoparticles. In literature, cationic polymers such as Polyethylenimine (PEI), which is the industry standard, have been used to stabilize IONPs because they can be used in magnetofections to deliver DNA or RNA. PEI however is known to interact very strongly with proteins and is cytotoxic, so as mentioned previously the Iron Oxide nanoparticles (IONPs) synthesized in this study were stabilized with amine-epoxide polymers because of the limitations of PEI. Four different amine-epoxide polymers which have good water solubility, biodegradability and less toxic than PEI were synthesized and used in the synthesis and stabilization of the magnetic nanoparticles and compared to PEI templated IONPs. These polymer-templated magnetic nanoparticles were also characterized by size, surface charge, Iron oxide content (ICP analysis) and superconducting quantum interference devices (SQUID) analysis to determine the magnetization values. TEM images were also used to determine the shape and size of the nanoparticles. All this was done in an effort to choose two or three leads that could be used in future work for magnetofections or drug delivery research.

Tamakloe, Beatrice

131

"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

132

Lanthanide doped nanoparticles as remote sensors for magnetic fields.  

PubMed

We report the effect of magnetic fields (MFs) on emission Eu-doped NaYF4 nanoparticles. A notable shift in the position of emission bands and the suppressed emission intensity are observed with the MF. These magnetic-optical interactions are explained in terms of the Zeeman effect, enhanced cross-relaxation rate and change of site symmetry. PMID:25123099

Chen, Ping; Zhang, Junpei; Xu, Beibei; Sang, Xiangwen; Chen, Weibo; Liu, Xiaofeng; Han, Junbo; Qiu, Jianrong

2014-10-01

133

Detection of rotavirus by serological trapping on antibody-coated electron microscope grids.  

PubMed Central

A serological trapping technique for detecting rotaviruses is described which involves coating electron microscope grids with protein A and specific rotavirus antiserum. The presence of a layer of antibodies on the grid increases the number of rotavirus particles that can be visualized. Thirty-five crude fecal extracts from infants suffering from diarrhea were examined by the serological trapping technique and by standard electron-microscopy. When the specimens were deposited on antibody-coated girds, 71% of them were found to contain virus particles, compared with 20% on standard uncoated grids. The method is simple and rapid and does away with the need to concentrate the specimens. Images PMID:6252237

Nicolaieff, A; Obert, G; van Regenmortel, M H

1980-01-01

134

Chemical attachment of magnetic nanoparticles through ``click chemistry''  

NASA Astrophysics Data System (ADS)

Iron nanoparticles were used as a test system to explore the functionalization and attachment of magnetic nanoparticles with two different functionalities through ``click chemistry.'' Two different samples of iron nanoparticles were modified with 5-azidopentanoic acid and with 5-hexynoic acid, respectively. This modification was followed by click chemistry to change the morphology of agglomeration. A combination of density functional theory calculations, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy was used to monitor each step of the process. Spectroscopies confirmed the success and completion of click reaction. Scanning electron microscopy images showed the change in size and morphology of the iron nanoparticles before and after click chemistry. Vibrating sample magnetometer study showed the majority of the magnetic properties were retained following functionalization and click reaction. Exploring similar approach for two types of materials with functionalization and attachment of hard magnetic materials and soft magnetic materials will be presented based on our initial studies of SmCo nanoparticles in a combination with iron nanoparticles.

Liu, Yue; Teplyakov, Andrew Y.; Hadjipanayis, George C.

2013-03-01

135

Assembly and magnetic properties of nickel nanoparticles on silicon nanowires  

SciTech Connect

The directed assembly of magnetic Ni nanoparticles at the tips of silicon nanowires is reported. Using electrodeposition Ni shells of thickness from 10 to 100 nm were selectively deposited on Au catalytic seeds at the ends of nanowires. Magnetic characterization confirms a low coercivity ({approx}115 Oe) ferromagnetic behavior at 300 K. This approach to multifunctional magnetic-semiconducting nanostructure assembly could be extended to electrodeposition of other materials on the nanowire ends, opening up novel ways of device integration. Such magnetically functionalized nanowires offer a new approach to developing novel highly localized magnetic probes for high resolution magnetic resonance force microscopy.

Picraux, Samuel T [Los Alamos National Laboratory; Manandhar, Pradeep [Los Alamos National Laboratory; Nazaretski, E [Los Alamos National Laboratory; Thompson, J [Los Alamos National Laboratory

2009-01-01

136

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

137

Bifunctional magnetic-fluorescent nanoparticles: synthesis, characterization, and cell imaging.  

PubMed

A new type of bifunctional magnetic-fluorescent Fe3O4@SiO2-PDI-PAA/Ca(2+) nanoparticles has been prepared by coating PDI-cored star polymers (PDI-PAA) onto the surface of Fe3O4@SiO2 core-shell nanostructures. The morphology and properties of the composite nanoparticles are investigated by transmission electron microscopy, ultraviolet-visible spectrometry, fluorescence spectrometry, and vibrating sample magnetometry. The composite nanoparticles display a strong red emission and superparamagnetic behavior at room temperature. The cell viability and uptake assays reveal good biocompatibility of these hybrid nanoparticles. Hence, the composite nanoparticles are of potential to be further explored as therapeutic vector in biomedical field. PMID:25691125

Lu, Yanjiao; Zheng, Yang; You, Shusen; Wang, Feng; Gao, Zhuo; Shen, Jie; Yang, Wantai; Yin, Meizhen

2015-03-11

138

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

139

The unusual magnetism of nanoparticle LaCoO3.  

PubMed

Bulk and nanoparticle powders of LaCoO3 (LCO) were synthesized and their magnetic and structural properties were studied using SQUID magnetometry and neutron diffraction. The bulk and large nanoparticles exhibit weak ferromagnetism (FM) below T ? 85 K and a crossover from strong to weak antiferromagnetic (AFM) correlations near a transition expressed in the lattice parameters, To?40 K. This crossover does not occur in the smallest nanoparticles; instead, the magnetic behavior is predominantly ferromagnetic. The amount of FM in the nanoparticles depends on the amount of Co3O4 impurity phase, which induces tensile strain on the LCO lattice. A core-interface model is introduced, with the core region exhibiting the AFM crossover and with FM in the interface region near surfaces and impurity phases. PMID:25872920

Durand, A M; Belanger, D P; Hamil, T J; Ye, F; Chi, S; Fernandez-Baca, J A; Booth, C H; Abdollahian, Y; Bhat, M

2015-05-01

140

Multifunctional magnetic and fluorescent core-shell nanoparticles for bioimaging  

NASA Astrophysics Data System (ADS)

Novel magnetic and fluorescent core-shell nanoparticles have been fabricated, which exhibit superparamagnetic behavior and emit strong near-infrared fluorescence. The nanoparticles are highly biocompatible and can be internalized into cells with nucleic accumulation via strong interaction with nucleic acids, implying potential applications in the biomedical field.Novel magnetic and fluorescent core-shell nanoparticles have been fabricated, which exhibit superparamagnetic behavior and emit strong near-infrared fluorescence. The nanoparticles are highly biocompatible and can be internalized into cells with nucleic accumulation via strong interaction with nucleic acids, implying potential applications in the biomedical field. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr06104g

Lu, Yanjiao; He, Bicheng; Shen, Jie; Li, Jie; Yang, Wantai; Yin, Meizhen

2015-01-01

141

Magnetic domains and surface effects in hollow maghemite nanoparticles  

NASA Astrophysics Data System (ADS)

In the present work, we investigate the magnetic properties of ferrimagnetic and noninteracting maghemite (?-Fe2O3) 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 arrangement in the different temperature regimes.

Cabot, Andreu; Alivisatos, A. Paul; Puntes, Víctor F.; Balcells, Lluís; Iglesias, Òscar; Labarta, Amílcar

2009-03-01

142

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

143

Functionalizing with glycopeptide dendrimers significantly enhances the hydrophilicity of the magnetic nanoparticles.  

PubMed

Magnetic nanoparticles functionalized with maltosylated glycopeptide dendrimers were prepared via azide-alkynyl click reaction. The functionalized magnetic nanoparticles exhibited high hydrophilicity and good efficiency in glycopeptide enrichment by HILIC. PMID:25666978

Li, Jinan; Wang, Fangjun; Liu, Jing; Xiong, Zhichao; Huang, Guang; Wan, Hao; Liu, Zheyi; Cheng, Kai; Zou, Hanfa

2015-02-19

144

Large-Scale First-Principles Calculations of Magnetic Nanoparticles  

Microsoft Academic Search

Modern supercomputers as the IBM Blue Gene\\/L provide the possibility to investigate large systems containing several hundred transition metal atoms. We present results on two examples, the size dependent evolution of structure and magnetism of elemental iron nanoparticles and the identification of structural comparison of competing morph ologies of near-stoichiometric Fe-Pt and Co-Pt nanoparticles, which are currently discussed as media

Markus Ernst Gruner; Georg Rollmann; Peter Entel

145

Lymph node localization of non-specific antibody-coated liposomes  

SciTech Connect

Subcutaneously injected small unilamellar liposomes are drained into the lymphatics and localized in the regional lymph nodes, and thus they can be used for the detection of metastatic spread in breast cancer patients and for delivery of drugs to diseased lymph nodes. An aqueous phase marker, (/sup 125/I)-polyvinylpyrrolidone, and a lipid phase marker, (/sup 3/H)-cholesterol, were used to study the lymph node localization of IgG-coated liposomes injected subcutaneously into mouse and rat footpads. The results show that human immunoglobulin G (IgG) coated liposomes are rapidly removed from the site of injection and are localized in the regional lymph nodes to a greater extent than control liposomes (i.e. liposomes without IgG). Free IgG was found to inhibit the uptake of IgG-coated liposomes by the lymph nodes. The localization of IgG-coated liposomes in the regional lymph nodes is influenced by charge of the liposomes. The results presented here suggest that antibody-coated liposomes may provide a more efficient way of delivering therapeutic agents to the lymph nodes in the treatment of diseases such as breast cancer with lymph node involvement. Similarly, monoclonal antibody-coated liposomes containing lymphoscintigraphic material may improve the detection of lymph node metastases. 26 references, 3 figures, 3 tables.

Mangat, S.; Patel, H.M.

1985-05-20

146

Nonequilibrium Magnetic Response of Anisotropic Superparamagnetic Nanoparticles and Possible Artifacts in Magnetic Particle Imaging  

PubMed Central

Magnetic responses of superparamagnetic nanoparticles to high-frequency AC magnetic fields with sufficiently large amplitudes are numerically simulated to exactly clarify the phenomena occurring in magnetic particle imaging. When the magnetic anisotropy energy inevitable in actual nanoparticles is taken into account in considering the magnetic potential, larger nanoparticles exhibit a delayed response to alternations of the magnetic fields. This kind of delay is rather remarkable in the lower-amplitude range of the field, where the assistance by the Zeeman energy to thermally activated magnetization reversal is insufficient. In some cases, a sign inversion of the third-order harmonic response was found to occur at some specific amplitude, despite the lack in DC bias magnetic field strength. Considering the attenuation of the AC magnetic field generated in the human body, it is possible that the phases of the signals from nanoparticles deep inside the body and those near the body surface are completely different. This may lead to artifacts in the reconstructed image. Furthermore, when the magnetic/thermal torque-driven rotation of the anisotropic nanoparticles as well as the magnetic anisotropy energy are taken into account, the simulated results show that, once the easy axes are aligned toward the direction of the DC bias magnetic field, it takes time to randomize them at the field-free point. During this relaxation, the third-order harmonic response depends highly upon the history of the magnetic field. This is because non-linearity of the anhysteretic magnetization curve for the superparamagnetic nanoparticles varies with the orientations of the easy axes. This history dependence may also lead to another artifact in magnetic particle imaging, when the scanning of the field-free point is faster than the Brownian relaxations. PMID:25775017

Mamiya, Hiroaki; Jeyadevan, Balachandran

2015-01-01

147

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

148

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

149

Magnetic properties of superparamagnetic nanoparticles loaded into silicon nanotubes  

PubMed Central

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. PACS 61.46.Fg; 62.23.Pq; 75.75.-c; 75.20.-g PMID:25170336

2014-01-01

150

Magnetic nanoparticles supported ionic liquids improve firefly luciferase properties.  

PubMed

Ionic liquids as neoteric solvents, microwave irradiation, and alternative energy source are becoming as a solvent for many enzymatic reactions. We recently showed that the incubation of firefly luciferase from Photinus pyralis with various ionic liquids increased the activity and stability of luciferase. Magnetic nanoparticles supported ionic liquids have been obtained by covalent bonding of ionic liquids-silane on magnetic silica nanoparticles. In the present study, the effects of [?-Fe2O3@SiO2][BMImCl] and [?-Fe2O3@SiO2][BMImI] were investigated on the structural properties and function of luciferase using circular dichroism, fluorescence spectroscopy, and bioluminescence assay. Enzyme activity and structural stability increased in the presence of magnetic nanoparticles supported ionic liquids. Furthermore, the effect of ingredients which were used was not considerable on K(m) value of luciferase for adenosine-5'-triphosphate and also K(m) value for luciferin. PMID:24492953

Noori, Ali Reza; Hosseinkhani, Saman; Ghiasi, Parisa; Akbari, Jafar; Heydari, Akbar

2014-03-01

151

Plasmon nanoparticle superlattices as optical-frequency magnetic metamaterials.  

PubMed

Nanocrystal superlattices have emerged as a new platform for bottom-up metamaterial design, but their optical properties are largely unknown. Here, we investigate their emergent optical properties using a generalized semi-analytic, full-field solver based on rigorous coupled wave analysis. Attention is given to superlattices composed of noble metal and dielectric nanoparticles in unary and binary arrays. By varying the nanoparticle size, shape, separation, and lattice geometry, we demonstrate the broad tunability of superlattice optical properties. Superlattices composed of spherical or octahedral nanoparticles in cubic and AB(2) arrays exhibit magnetic permeabilities tunable between 0.2 and 1.7, despite having non-magnetic constituents. The retrieved optical parameters are nearly polarization and angle-independent over a broad range of incident angles. Accordingly, nanocrystal superlattices behave as isotropic bulk metamaterials. Their tunable permittivities, permeabilities, and emergent magnetism may enable new, bottom-up metamaterials and negative index materials at visible frequencies. PMID:22772268

Alaeian, Hadiseh; Dionne, Jennifer A

2012-07-01

152

A novel strategy for functionalizable photoluminescent magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

This study presents functionalizable photoluminescent magnetic iron oxide nanoparticles (PLMNPs) produced by heating magnetic nanoparticles coated with non-photoluminescent hydrophilic poly(acrylic acid) (PAA) but without any add-on photoluminescent chemicals. The photoluminescence of PLMNPs is originated from a carbon nanodot layer that is converted from the PAA polymer coating layer during the heating process. Interestingly, PLMNPs are more photo-stable than conventional organic dyes. Further functionalization of PLMNPs is easily achieved through the coupling reaction with carboxyl groups of the coating layer on the surface. PLMNPs can be remotely heated by applying an alternating magnetic field due to the superparamagnetism, and are found to have good heating efficiency. All these advantages make these nanoparticles appealing for various biomedical applications, such as dual modality imaging and hyperthermia treatment.

Yan, Huan; Sung, Baeckkyoung; Kim, Min-Ho; Kim, Chanjoong

2014-12-01

153

TOPICAL REVIEW: Functionalisation of magnetic nanoparticles for applications in biomedicine  

NASA Astrophysics Data System (ADS)

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 treatment for malignant cells, site-specific drug delivery and the manipulation of cell membranes. To this end a variety of iron oxide particles have been synthesized. A common failure in targeted systems is due to the opsonization of the particles on entry into the bloodstream, rendering the particles recognizable by the body's major defence system, the reticulo-endothelial system. This review discusses each of the above bio-applications of such magnetic nanoparticles and details some of the main recent advances in biological research.

Berry, Catherine C.; Curtis, Adam S. G.

2003-07-01

154

Quadrupole magnetic field-flow fractionation: A novel technique for the characterization of magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Quadrupole magnetic field-flow fractionation (MgFFF) is an analytical separation and characterization technique for nano- and micro-sized magnetic particles. It fractionates particles according to their content of magnetite or other magnetic material. The potential and versatility of MgFFF for separation and characterization of magnetic nanoparticles, such as those used for immunospecific labeling of biological cells for magnetic separation, is demonstrated. A broadly polydisperse sample of dextran-coated magnetite nanoparticles was eluted under programmed field decay conditions, and quantitative data concerning the distribution of magnetite content were determined from the elution profile using a data reduction method.

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

2007-04-01

155

Nanoparticles  

NASA Astrophysics Data System (ADS)

MnFe2O4 nanoparticles of various particle sizes were prepared by co-precipitation, in which different hydroxide concentrations were employed to control particle growth. X-ray diffraction and scanning electron microscopy were used to investigate the nanoparticle structure and morphology (shape and size). The particle size increased with increasing hydroxide concentration. The magnetization and coercivity field were measured by vibrating sample magnetometry. Changes in magnetic behavior were observed in the magnetic hysteresis loop curves of nanoparticles with increasing hydroxide concentration. In the absence of hydroxide, nanoparticles exhibited paramagnetic behavior. Increasing the hydroxide concentration caused a gradual conversion to ferrimagnetic behavior. An increased Néel temperature was observed with increasing hydroxide concentration, and the saturation magnetization exhibited a sharp decrease. Nonuniform hysteresis was observed in the magnetization curve for the sample prepared from hydroxide and ammonium.

Vaez-Zadeh, Mehdi; Mohammadi, Ali

2014-07-01

156

Simulating magnetic nanoparticle behavior in low-field MRI under transverse rotating fields and imposed fluid flow  

Microsoft Academic Search

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 rads?1.

P. Cantillon-Murphy; L. L. Wald; E. Adalsteinsson; M. Zahn

2010-01-01

157

The production of magnetic nanoparticles of Iron Oxide by arc discharge in water  

NASA Astrophysics Data System (ADS)

Nanoparticles can be utilized for any practical application. In recent years; considerable attention has been paid to iron oxide magnetic. Iron oxide nanoparticles are the class of nanoparticle which can have useful magnetic properties. In this research, magnetic iron oxide nanoparticles were produced by Arc discharge method in water. Structural analysis carried out by X-ray diffraction analysis (XRD), Scanning Electron Microscopy (SEM), and Spectrophotometer. Various magnetic nanoparticles like iron carbide (Fe3c), magnetic iron oxide (magnetite /maghemite) are obtained by arc discharge method in water. In this work have been showed, the influence of the time duration on the number of magnetic nanoparticles and the influence of the gap between the two electrodes on particle structure and size distribution. Furthermore, when iron nanoparticles are used under applied magnetic field, the particles would move in the direction of magnetic field. When the magnetic field is removed, the particles stop moving and still remain stably suspend in the dielectric liquid.

Yousefi, Hamid Reza; Fathollah, Sara; Nikeyn, Maryam; Khatami, Shohreh

2012-10-01

158

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.

159

A Two-Magnet System to Push Therapeutic Nanoparticles  

PubMed Central

Magnetic fields can be used to direct magnetically susceptible nanoparticles to disease locations: to infections, blood clots, or tumors. Any single magnet always attracts (pulls) ferro- or para-magnetic particles towards it. External magnets have been used to pull therapeutics into tumors near the skin in animals and human clinical trials. Implanting magnetic materials into patients (a feasible approach in some cases) has been envisioned as a means of reaching deeper targets. Yet there are a number of clinical needs, ranging from treatments of the inner ear, to antibiotic-resistant skin infections and cardiac arrhythmias, which would benefit from an ability to magnetically “inject”, or push in, nanomedicines. We develop, analyze, and experimentally demonstrate a novel, simple, and effective arrangement of just two permanent magnets that can magnetically push particles. Such a system might treat diseases of the inner ear; diseases which intravenously injected or orally administered treatments cannot reach due to the blood-brain barrier. PMID:21243119

Shapiro, Benjamin; Dormer, Kenneth; Rutel, Isaac B.

2010-01-01

160

A Two-Magnet System to Push Therapeutic Nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic fields can be used to direct magnetically susceptible nanoparticles to disease locations: to infections, blood clots, or tumors. Any single magnet always attracts (pulls) ferro- or para-magnetic particles towards it. External magnets have been used to pull therapeutics into tumors near the skin in animals and human clinical trials. Implanting magnetic materials into patients (a feasible approach in some cases) has been envisioned as a means of reaching deeper targets. Yet there are a number of clinical needs, ranging from treatments of the inner ear, to antibiotic-resistant skin infections and cardiac arrhythmias, which would benefit from an ability to magnetically "inject", or push in, nanomedicines. We develop, analyze, and experimentally demonstrate a novel, simple, and effective arrangement of just two permanent magnets that can magnetically push particles. Such a system might treat diseases of the inner ear; diseases which intravenously injected or orally administered treatments cannot reach due to the blood-brain barrier.

Shapiro, Benjamin; Dormer, Kenneth; Rutel, Isaac B.

2010-12-01

161

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.; Della Torre, Edward; Bennett, Lawrence H.

2014-09-01

162

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

163

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

164

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

165

Magnetic Nanoparticles in-vivo Detection of Transplant Rejection  

NASA Astrophysics Data System (ADS)

Superparamagnetic nanoparticles are being used to develop methodology for the in-vivo detection and imaging of immune system attacks on transplanted organs. The signature for impending rejection of a transplant is enhanced presence of T-cells. Magnetic nanoparticles coated with specific antibodies (CD-2 and CD-3) will target and attach to these T-cells. Approximately 3 .10^5 nanoparticles can attach to each cell. When a pulsed external magnetic field is applied to the decorated cells for a fraction of a second, magnetic moments of the nanoparticles aligned with the field. After the pulse is switched off, the net magnetic moment decays over several seconds by the Nèel mechanism. The resulting magnetic remanence field (typically 10-11 T) is measured using a multi-channel SQUID array. We present the data from live T-cells placed in realistic kidney phantom. The detection sensitivity was ˜2.10^3 T-cells - a small fraction of the number actually invading the rejected transplant. The 7-channel SQUID array allows us to image the cell clusters with a few millimeters resolution.

Flynn, E. R.; Bryant, H. C.; Larson, R. S.; Sergatskov, D. A.

2006-03-01

166

Switching of magnetization by nonlinear resonance studied in single nanoparticles.  

PubMed

Magnetization reversal in magnetic particles is one of the fundamental issues in magnetic data storage. Technological improvements require the understanding of dynamical magnetization reversal processes at nanosecond time scales. New strategies are needed to overcome current limitations. For example, the problem of thermal stability of the magnetization state (superparamagnetic limit) can be pushed down to smaller particle sizes by increasing the magnetic anisotropy. High fields are then needed to reverse the magnetization, which are difficult to achieve in current devices. Here we propose a new method to overcome this limitation. A constant applied field, well below the switching field, combined with a radio-frequency (RF) field pulse can reverse the magnetization of a nanoparticle. The efficiency of this method is demonstrated on a 20-nm-diameter cobalt particle by using the microSQUID (superconducting quantum interference device) technique. Other applications of this method might be nucleation or depinning of domain walls. PMID:12883551

Thirion, Christophe; Wernsdorfer, Wolfgang; Mailly, Dominique

2003-08-01

167

Transformation of Escherichia coli mediated by magnetic nanoparticles in pulsed magnetic field  

Microsoft Academic Search

A magneto-transformation method was developed for transferring plasmid DNA into Escherichia coli. Superparamagnetic nanoparticles (Fe3O4) having the saturation magnetization up to 68emu\\/g were prepared by the method of co-precipitation at alkaline and thermal conditions, coated with polyethyleneimine (PEI), and then complexed with negatively charged DNA molecules. Plasmid DNA (pGEX-1?T) attached to the PEI-coated magnetic nanoparticles could be transformed into E.

Ji-Yao Chen; Ya-Ling Liao; Tzu-Hsien Wang; Wen-Chien Lee

2006-01-01

168

Characterization of magnetic nanoparticles using programmed quadrupole magnetic field-flow fractionation  

PubMed Central

Quadrupole magnetic field-flow fractionation is a relatively new technique for the separation and characterization of magnetic nanoparticles. Magnetic nanoparticles are often of composite nature having a magnetic component, which may be a very finely divided material, and a polymeric or other material coating that incorporates this magnetic material and stabilizes the particles in suspension. There may be other components such as antibodies on the surface for specific binding to biological cells, or chemotherapeutic drugs for magnetic drug delivery. Magnetic field-flow fractionation (MgFFF) has the potential for determining the distribution of the magnetic material among the particles in a given sample. MgFFF differs from most other forms of field-flow fractionation in that the magnetic field that brings about particle separation induces magnetic dipole moments in the nanoparticles, and these potentially can interact with one another and perturb the separation. This aspect is examined in the present work. Samples of magnetic nanoparticles were analysed under different experimental conditions to determine the sensitivity of the method to variation of conditions. The results are shown to be consistent and insensitive to conditions, although magnetite content appeared to be somewhat higher than expected. PMID:20732895

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

2010-01-01

169

Pulsed magneto-motive ultrasound imaging to detect intracellular trafficking of magnetic nanoparticles  

PubMed Central

As applications of nanoparticles in medical imaging and biomedicine rapidly expand, the interactions of nanoparticles with living cells have become an area of active interest. For example, intracellular trafficking of nanoparticles – an important part of cell-nanoparticle interaction, has been well studied using plasmonic nanoparticles and optical or optics-based techniques due to the change in optical properties of the nanoparticle aggregates. However, magnetic nanoparticles, despite their wide range of clinical applications, do not exhibit plasmonic-resonant properties and therefore their intracellular aggregation cannot be detected by optics-based imaging techniques. In this study, we investigated the feasibility of a novel imaging technique – pulsed magneto-motive ultrasound (pMMUS), to identify intracellular trafficking of endocytosed magnetic nanoparticles. In pulsed magneto-motive ultrasound imaging a focused, high intensity, pulsed magnetic field is used to excite the cells labeled with magnetic nanoparticles, and ultrasound imaging is then used to monitor the mechanical response of the tissue. We demonstrated previously that clusters of magnetic nanoparticles amplify the pMMUS signal in comparison to signal from individual nanoparticles. Here we further demonstrate that pMMUS imaging can identify interaction between magnetic nanoparticles and living cells, i.e. intracellular aggregation of nanoparticles within the cells. The results of our study suggest that pMMUS imaging can not only detect the presence of magnetic nanoparticles but also provides information about their intracellular trafficking non-invasively and in real-time. PMID:21926454

Mehrmohamamdi, Mohammad; Qu, Min; Ma, Li L.; Romanovicz, Dwight K.; Johnston, Keith P.; Sokolov, Konstantin V.; Emelianov, Stanislav Y.

2012-01-01

170

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

171

Preparation and characterization of functional silica hybrid magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

We report on the synthesis and characterization of functional silica hybrid magnetic nanoparticles (SHMNPs). The co-condensation of 3-aminopropyltriethoxysilane (APTES) and tetraethyl orthosilicate (TEOS) in presence of superparamagnetic iron oxide nanoparticles (SPIONs) leads to hybrid magnetic silica particles that are surface-functionalized with primary amino groups. In this work, a comprehensive synthetic study is carried out and completed by a detailed characterization of hybrid particles' size and morphology, surface properties, and magnetic responses using different techniques. Depending on the mass ratio of SPIONs and the two silanes (TEOS and APTES), we were able to adjust the number of surface amino groups and tune the magnetic properties of the superparamagnetic hybrid particles.

Digigow, Reinaldo G.; Dechézelles, Jean-François; Dietsch, Hervé; Geissbühler, Isabelle; Vanhecke, Dimitri; Geers, Christoph; Hirt, Ann M.; Rothen-Rutishauser, Barbara; Petri-Fink, Alke

2014-08-01

172

Doping induced magnetism in Co-ZnS nanoparticles  

NASA Astrophysics Data System (ADS)

Zn 1-xCo xS nanoparticles with x=0, 0.1, 0.2, and 0.3 were synthesized by the co-precipitation method using thiophenol as capping agent. The effect of Co doping on the structural, optical and magnetic properties are investigated. The X-ray diffraction patterns show single phase with cubic structure and the images of Transmission Electron Microscopy indicate an average particle size of 39 nm. Significant blue shift in the optical absorbing band edge was observed with increasing Co doping. In the Co doped samples, room-temperature (RT) magnetic hysteresis is observed and the magnetization reduces with increasing Co content. However, these samples show paramagnetic resonance instead of ferromagnetic resonance at both 300 and 80 K, suggesting that the origin of RT magnetization in these Zn 1-xCo xS nanoparticles involves with the frustration of antiferromagnetic interactions.

Sambasivam, S.; Paul Joseph, D.; Lin, J. G.; Venkateswaran, C.

2009-10-01

173

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

174

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

175

Design of magnetic nanoparticles-assisted drug delivery system.  

PubMed

Magnetic nanoparticles (MNPs) have been designed for multifaceted applications such as contrast agents in magnetic resonance imaging (MRI) diagnosis, drug/gene carriers for different kinds of therapeutic agents, tissue repair, hyperthermia, immunoassay, and cell separation/sensing. This review highlights synthesis methods, stabilizers used for surface coating on MNPs, and target ligands for ferrying payloads to an interested disease area. Some of the recent biomedical applications of MNPs in the field of drug and DNA targeting delivery are extensively reviewed. PMID:21736546

Chen, Guo-Jing; Wang, Li-Fang

2011-01-01

176

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

177

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

178

Dipolar Magnetism in Ordered and Disordered Low-Dimensional Nanoparticle Assemblies  

PubMed Central

Magnetostatic (dipolar) interactions between nanoparticles promise to open new ways to design nanocrystalline magnetic materials and devices if the collective magnetic properties can be controlled at the nanoparticle level. Magnetic dipolar interactions are sufficiently strong to sustain magnetic order at ambient temperature in assemblies of closely-spaced nanoparticles with magnetic moments of ? 100??B. Here we use electron holography with sub-particle resolution to reveal the correlation between particle arrangement and magnetic order in self-assembled 1D and quasi-2D arrangements of 15?nm cobalt nanoparticles. In the initial states, we observe dipolar ferromagnetism, antiferromagnetism and local flux closure, depending on the particle arrangement. Surprisingly, after magnetic saturation, measurements and numerical simulations show that overall ferromagnetic order exists in the present nanoparticle assemblies even when their arrangement is completely disordered. Such direct quantification of the correlation between topological and magnetic order is essential for the technological exploitation of magnetic quasi-2D nanoparticle assemblies. PMID:23390584

Varón, M.; Beleggia, M.; Kasama, T.; Harrison, R. J.; Dunin-Borkowski, R. E.; Puntes, V. F.; Frandsen, C.

2013-01-01

179

Hybrid composites of xanthan and magnetic nanoparticles for cellular uptake.  

PubMed

We describe a fast and simple method to prepare composite films of magnetite nanoparticles and xanthan networks. The particles are distributed close to hybrid film surface, generating a coercivity of 27 ± 2 Oe at 300 K. The proliferation of fibroblast cells on the hybrid composites was successful, particularly when an external magnetic field was applied. PMID:23774749

Bueno, Vânia Blasques; Silva, Anielle Martins; Barbosa, Leandro Ramos Souza; Catalani, Luiz Henrique; Teixeira-Neto, Erico; Cornejo, Daniel Reinaldo; Petri, Denise Freitas Siqueira

2013-11-01

180

Proteolytic Surface Functionalization Enhances in Vitro Magnetic Nanoparticle  

E-print Network

Proteolytic Surface Functionalization Enhances in Vitro Magnetic Nanoparticle Mobility through superparamagnetic NPs overcame these barriers and moved through in vitro extracellular matrix (ECM) at 90 µm h-1 to the developing neural crest.11,12 Embryo implantation following fertilization is marked by dramatic increase

181

Development of novel magnetic nanoparticles for hyperthermia cancer therapy  

NASA Astrophysics Data System (ADS)

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.

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

2011-03-01

182

Biofunctionalized magnetic nanoparticles for in vitro labeling and in vivo locating specific biomolecules  

NASA Astrophysics Data System (ADS)

In this work, we developed processes to biofunctionalize magnetic nanoparticles dispersed in phosphate buffer saline solution. For future clinical utility, magnetic nanoparticles were biofunctionalized with anti-vascular cell adhesion molecule-1 (VCAM-1) to label the VCAM-1 molecule, which served as an indicator for the lesions prone to vulnerable atherosclerotic plaque formation. The biofunctionalized magnetic nanoparticles were used to magnetically label, in vitro, cells expressing VCAM-1, as well as to locate the vulnerable aortic lesions of hypercholesterolemic rabbits with the aid of magnetic resonance imaging. In addition to demonstrating the feasibility of using biofunctionalized magnetic nanoparticles for biomolecule assays, the relevant physical mechanisms are discussed.

Wu, C. C.; Lin, L. Y.; Lin, L. C.; Huang, H. C.; Yang, Y. F.; Liu, Y. B.; Tsai, M. C.; Gao, Y. L.; Wang, W. C.; Hung, S. W.; Yang, S. Y.; Horng, H. E.; Yang, H. C.; Tseng, W. Y. I.; Yeh, H. I.; Hsuan, C. F.; Lee, T. L.; Tseng, W. K.

2008-04-01

183

Strong and moldable cellulose magnets with high ferrite nanoparticle content.  

PubMed

A major limitation in the development of highly functional hybrid nanocomposites is brittleness and low tensile strength at high inorganic nanoparticle content. Herein, cellulose nanofibers were extracted from wood and individually decorated with cobalt-ferrite nanoparticles and then for the first time molded at low temperature (<120 °C) into magnetic nanocomposites with up to 93 wt % inorganic content. The material structure was characterized by TEM and FE-SEM and mechanically tested as compression molded samples. The obtained porous magnetic sheets were further impregnated with a thermosetting epoxy resin, which improved the load-bearing functions of ferrite and cellulose material. A nanocomposite with 70 wt % ferrite, 20 wt % cellulose nanofibers, and 10 wt % epoxy showed a modulus of 12.6 GPa, a tensile strength of 97 MPa, and a strain at failure of ca. 4%. Magnetic characterization was performed in a vibrating sample magnetometer, which showed that the coercivity was unaffected and that the saturation magnetization was in proportion with the ferrite content. The used ferrite, CoFe2O4, is a magnetically hard material, demonstrated by that the composite material behaved as a traditional permanent magnet. The presented processing route is easily adaptable to prepare millimeter-thick and moldable magnetic objects. This suggests that the processing method has the potential to be scaled-up for industrial use for the preparation of a new subcategory of magnetic, low-cost, and moldable objects based on cellulose nanofibers. PMID:25331121

Galland, Sylvain; Andersson, Richard L; Ström, Valter; Olsson, Richard T; Berglund, Lars A

2014-11-26

184

Morphology and magnetic flux distribution in superparamagnetic, single-crystalline Fe3O4 nanoparticle rings  

NASA Astrophysics Data System (ADS)

This study reports on the correlation between crystal orientation and magnetic flux distribution of Fe3O4 nanoparticles in the form of self-assembled rings. High-resolution transmission electron microscopy demonstrated that the nanoparticles were single-crystalline, highly monodispersed, (25 nm average diameter), and showed no appreciable lattice imperfections such as twins or stacking faults. Electron holography studies of these superparamagnetic nanoparticle rings indicated significant fluctuations in the magnetic flux lines, consistent with variations in the magnetocrystalline anisotropy of the nanoparticles. The observations provide useful information for a deeper understanding of the micromagnetics of ultrasmall nanoparticles, where the magnetic dipolar interaction competes with the magnetic anisotropy.

Takeno, Yumu; Murakami, Yasukazu; Sato, Takeshi; Tanigaki, Toshiaki; Park, Hyun Soon; Shindo, Daisuke; Ferguson, R. Matthew; Krishnan, Kannan M.

2014-11-01

185

Thermal fluctuations of magnetic nanoparticles: Fifty years after Brown  

NASA Astrophysics Data System (ADS)

The reversal time, superparamagnetic relaxation time, of the magnetization of fine single domain ferromagnetic nanoparticles owing to thermal fluctuations plays a fundamental role in information storage, paleomagnetism, biotechnology, etc. Here a comprehensive tutorial-style review of the achievements of fifty years of development and generalizations of the seminal work of Brown [Phys. Rev. 130, 1677 (1963)] on thermal fluctuations of magnetic nanoparticles is presented. Analytical as well as numerical approaches to the estimation of the damping and temperature dependence of the reversal time based on Brown's Fokker-Planck equation for the evolution of the magnetic moment orientations on the surface of the unit sphere are critically discussed while the most promising directions for future research are emphasized.

Coffey, William T.; Kalmykov, Yuri P.

2012-12-01

186

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

187

Imaging magnetic nanoparticles using the signal's frequency spectrum  

NASA Astrophysics Data System (ADS)

Current methods of magnetic particle imaging generate a signal by cyclically saturating nanoparticles creating measurable harmonics in the induced magnetization. The sensitivity promises to be competitive with SPECT so molecular imaging is possible. The signal was localized by saturating the nanoparticles outside a voxel using a strong static magnetic field and sweeping the voxel across the sample to form an image. However, in applications where enough nanoparticles are present, signal can be detected at several higher harmonic frequencies and we show that the distribution of signal between those frequencies contributes localizing information. We tested one-dimensional implementations but the methods can be generalized to three dimensions. Spatial encoding was accomplished by using multiple drive frequencies that varied spatially. Two drive coils tuned to different drive frequencies and mounted on the same axis were used to explore the method. The response was measured from a single sample of iron oxide nanoparticles at eight positions along that axis to estimate response function for the reconstruction. Then two identical samples were placed at pairs of locations to test the method. The sample positions were reconstructed from the measured spectrum of the signal generated. The number of independent parameters is limited but four independent parameters can be achieved with very good conditioning and eight independent parameters can be achieved with reasonable conditioning.

Weaver, John B.; Rauwerdink, Adam M.; Trembly, B. Stuart; Sullivan, Charles R.

2008-03-01

188

Magnetic nanoparticle migration in microfluidic two-phase flow  

Microsoft Academic Search

Continuous separation of superparamagnetic nanoparticles in a\\u000a microfluidic system has numerous applications, especially in novel\\u000a sensors based technology platforms. We have studied a simple\\u000a microfluidic system with two fluidic inlets, resulting in two-phase flow\\u000a of identical aqueous fluids. Magnetic nanoparticles were entrained in\\u000a de-ionized water entering one inlet channel, while the other inlet\\u000a channel had only de-ionized water input. The

Liqun Wu; Yong Zhang; Moorthi Palaniapan; Partha Roy

2009-01-01

189

Random lasing action in magnetic nanoparticles doped dye solutions  

NASA Astrophysics Data System (ADS)

Fe3O4@SiO2 nanoparticles were used as scatters in Rhodamine B solutions, and coherent random lasing was achieved. It was revealed that Fe3O4@SiO2 doped dye solution has a magnetically controllable feature. When external magnetic field is applied, the laser peaks would disappear if the diameter of Fe3O4 is relatively large (~100 nm), while the laser peaks would exist if the diameter of Fe3O4 is relatively small (~12 nm). This kind of random laser may has potential applications in fabricating magnetic sensors and integrated optical device.

Ye, Lihua; Lu, Jincheng; Lv, Changgui; Feng, Yangyang; Zhao, Chong; Wang, Zhuyuan; Cui, Yiping

2015-04-01

190

Magnetism in nanoparticles: beyond the effect of particle size.  

PubMed

A set of investigations on selected samples of nanosized cobalt ferrite are reviewed, aimed at studying the various factors affecting the magnetic properties of nanoparticles. Specifically, the effects of inter-particle interactions, of structural and magnetic order, both in the core and on the surface of the particle, have been examined. All factors render the control of the magnetic properties of nanosystems quite difficult, but, at the same time, they also offer the opportunity of tuning them properly, so that materials for specific applications may be created. PMID:19579233

Peddis, Davide; Cannas, Carla; Musinu, Anna; Piccaluga, Giorgio

2009-08-10

191

Magnetic properties of a single transverse Ising ferrimagnetic nanoparticle  

NASA Astrophysics Data System (ADS)

Using the effective field theory with a probability distribution technique that accounts for the self-spin correlation function, the thermal and the magnetic properties of a single Ising nanoparticle consisting of a ferromagnetic core, a ferromagnetic surface shell and a ferrimagnetic interface coupling are examined. The effect of the transverse field in the surface shell, the exchange interactions between core/shell and in surface shell on the free energy, thermal magnetization, specific heat and susceptibility are studied. A number of interesting phenomena have been found such as the existence of the compensation phenomenon and the magnetization profiles exhibit P-type, N-type and Q-type behaviors.

Bouhou, S.; El Hamri, M.; Essaoudi, I.; Ainane, A.; Ahuja, R.

2015-01-01

192

Magnet-induced temporary superhydrophobic coatings from one-pot synthesized hydrophobic magnetic nanoparticles.  

PubMed

In this paper, we report on the production of superhydrophobic coatings on various substrates (e.g., glass slide, silicon wafer, aluminum foil, plastic film, nanofiber mat, textile fabrics) using hydrophobic magnetic nanoparticles and a magnet-assembly technique. Fe(3)O(4) magnetic nanoparticles functionalized with a thin layer of fluoroalkyl silica on the surface were synthesized by one-step coprecipitation of Fe(2+)/Fe(3+) under an alkaline condition in the presence of a fluorinated alkyl silane. Under a magnetic field, the magnetic nanoparticles can be easily deposited on any solid substrate to form a thin superhydrophobic coating with water contact angle as high as 172 degrees , and the surface superhydrophobicity showed very little dependence on the substrate type. The particulate coating showed reasonable durability because of strong aggregation effect of nanoparticles, but the coating layer can be removed (e.g., by ultrasonication) to restore the original surface feature of the substrates. By comparison, the thin particle layer deposited under no magnetic field showed much lower hydrophobicity. The main reason for magnet-induced superhydrophobic surfaces is the formation of nano- and microstructured surface features. Such a magnet-induced temporary superhydrophobic coating may have wide applications in electronic, biomedical, and defense-related areas. PMID:20397642

Fang, Jian; Wang, Hongxia; Xue, Yuhua; Wang, Xungai; Lin, Tong

2010-05-01

193

Doping induced magnetism in Co-ZnS nanoparticles  

SciTech Connect

Zn{sub 1-x}Co{sub x}S nanoparticles with x=0, 0.1, 0.2, and 0.3 were synthesized by the co-precipitation method using thiophenol as capping agent. The effect of Co doping on the structural, optical and magnetic properties are investigated. The X-ray diffraction patterns show single phase with cubic structure and the images of Transmission Electron Microscopy indicate an average particle size of 39 nm. Significant blue shift in the optical absorbing band edge was observed with increasing Co doping. In the Co doped samples, room-temperature (RT) magnetic hysteresis is observed and the magnetization reduces with increasing Co content. However, these samples show paramagnetic resonance instead of ferromagnetic resonance at both 300 and 80 K, suggesting that the origin of RT magnetization in these Zn{sub 1-x}Co{sub x}S nanoparticles involves with the frustration of antiferromagnetic interactions. - Graphical abstract: Figure shows the magnetization data of Zn{sub 1-x}Co{sub x}S (0.1<=x<=0.3) nanoparticles annealed at 573 K/2 h in vacuum and measured at 300 K. This interesting feature of systematic reduction in magnetization may be due to introduction of antiferromagnetic ordering with increasing 'Co' concentration which may be due to competition between the antiferromagnetic and ferromagnetic ordering within the sample. One could also observe the exchange bias effect which is an interface interaction observed in a ferromagnetic-antiferromagnetic mixture. The exchange bias field (loop shift) towards negative field was around 63 Oe for the Zn{sub 1-x}Co{sub x}S (0.1<=x<=0.3) nanoparticles.

Sambasivam, S. [Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan (China); Paul Joseph, D. [Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600025 (India); Lin, J.G., E-mail: jglin@ntu.edu.t [Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan (China); Venkateswaran, C. [Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600025 (India)

2009-10-15

194

Magnetic/gold nanoparticle functionalized biocompatible microcapsules with sensitivity to laser irradiation.  

PubMed

Nanocomposite microcapsules with both gold and magnetite nanoparticles in the shell were prepared in a layer-by-layer procedure using biocompatible polyelectrolytes and nanoparticles. The process of a nanocomposite multilayer formation was investigated using a quartz crystal microbalance (QCM). In addition, nanocomposite microcapsules were characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). It is found that the amount of adsorbed nanoparticles is similar for nanoparticles of various sizes, while the concentration of gold nanoparticles in the shell is higher for smaller nanoparticles. Adsorption of gold nanoparticles is found to be more effective than adsorption of magnetic nanoparticles. Multifunctionality of microcapsules is manifested by dual: magnetic and optical responses. Iron oxide nanoparticles embedded in the microcapsule shell allowed for control over capsules positioning by external magnetic fields. Furthermore, the nanocomposite microcapsules could be opened by laser irradiation; these results are of interest for medical and biological applications. PMID:19015796

Gorin, Dmitry A; Portnov, Sergey A; Inozemtseva, Olga A; Luklinska, Zofia; Yashchenok, Alexey M; Pavlov, Anton M; Skirtach, Andre G; Möhwald, Helmuth; Sukhorukov, Gleb B

2008-12-01

195

Cobalt silica magnetic nanoparticles with functional surfaces  

NASA Astrophysics Data System (ADS)

Cobalt nanoparticles encased in polysiloxane block copolymers have been heated at 600-700 °C to form protective shells around the particles, which contain crosslinked Si-O structures, and to anneal the cobalt. Methods to functionalize and modify the surfaces of the pyrolyzed/annealed silica-cobalt complexes with amines, isocyanates, poly(ethylene oxide), poly( L-lactide) and polydimethylsiloxane (PDMS) are presented.

Vadala, Michael L.; Zalich, Michael A.; Fulks, David B.; St. Pierre, Tim G.; Dailey, James P.; Riffle, Judy S.

2005-05-01

196

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

197

Fluorescence Modified Chitosan-Coated Magnetic Nanoparticles for High-Efficient Cellular Imaging  

NASA Astrophysics Data System (ADS)

Labeling of cells with nanoparticles for living detection is of interest to various biomedical applications. In this study, novel fluorescent/magnetic nanoparticles were prepared and used in high-efficient cellular imaging. The nanoparticles coated with the modified chitosan possessed a magnetic oxide core and a covalently attached fluorescent dye. We evaluated the feasibility and efficiency in labeling cancer cells (SMMC-7721) with the nanoparticles. The nanoparticles exhibited a high affinity to cells, which was demonstrated by flow cytometry and magnetic resonance imaging. The results showed that cell-labeling efficiency of the nanoparticles was dependent on the incubation time and nanoparticles’ concentration. The minimum detected number of labeled cells was around 104 by using a clinical 1.5-T MRI imager. Fluorescence and transmission electron microscopy instruments were used to monitor the localization patterns of the magnetic nanoparticles in cells. These new magneto-fluorescent nanoagents have demonstrated the potential for future medical use.

Ge, Yuqing; Zhang, Yu; He, Shiying; Nie, Fang; Teng, Gaojun; Gu, Ning

2009-04-01

198

Iron oxide nanoparticles coated with gold: Enhanced magnetic moment due to interfacial effects  

NASA Astrophysics Data System (ADS)

In this paper, we show that when nanoparticles of Fe3O4 are coated with gold there is a distinct enhancement of magnetization by a factor of six. This increase of magnetization has been attributed to large orbital magnetic moment formation at the magnetic particle/Au (core/shell) interface. Our theoretical analysis indicates that the enhanced magnetism observed in Fe3O4-Au (core-shell) nanoparticles is an interfacial effect. The origin of magnetism in Au as an interfacial phenomenon is supported by the observation of positive magnetization in citrate coated gold nanoparticles. In citrate coated gold nanoparticles, we observe a crossover from positive magnetization value to negative magnetization value upon increasing magnetic field indicating cancellation of interfacial magnetization by the diamagnetic contribution from the bulk. We propose a theoretical formalism which semi-quantitatively explains our experimental results and supports the origin of magnetization in Au as an interfacial effect.

Banerjee, S.; Raja, S. O.; Sardar, M.; Gayathri, N.; Ghosh, B.; Dasgupta, A.

2011-06-01

199

Degradability of superparamagnetic nanoparticles in a model of intracellular environment: follow-up of magnetic, structural and chemical properties  

Microsoft Academic Search

The unique magnetic properties of iron oxide nanoparticles have paved the way for various biomedical applications, such as magnetic resonance cellular imaging or magnetically induced therapeutic hyperthermia. Living cells interact with nanoparticles by internalizing them within intracellular acidic compartments. Although no acute toxicity of iron oxide nanoparticles has been reported up to now, the mechanisms of nanoparticle degradation by the

Michael Lévy; Florence Lagarde; Valentin-Adrian Maraloiu; Marie-Geneviève Blanchin; François Gendron; Claire Wilhelm; Florence Gazeau

2010-01-01

200

Biomedical Applications of Magnetic Nanoparticles: Delivering Genes and Remote Control of Cells  

NASA Astrophysics Data System (ADS)

The use of magnetic micro- and nanoparticles for biomedical applications was first proposed in the 1920s as a way to measure the rehological properties of the cell's cytoplasm. Since that time, magnetic micro- and nanoparticle synthesis, coating and bio-functionalization have advanced significantly, as have the applications for these particles. Magnetic micro- and nanoparticles are now used in a variety of biomedical techniques such as targeted drug delivery, MRI contrast enhancement, gene transfection, immno-assay and cell sorting. More recently, magnetic micro- and nanoparticles have been used to investigate and manipulate cellular processes both in vitro and in vivo. This talk will focus on magnetic nanoparticle targeting to and actuation of cell surface receptors to control cell signaling cascades to control cell behavior. This technology has applications in disease therapy, cell engineering and regenerative medicine. The use of magnetic nanoparticles and oscillating magnet arrays for enhanced gene delivery will also be discussed.

Dobson, Jon

2013-03-01

201

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

202

Targeting of systemically-delivered magnetic nanoparticle hyperthermia using a noninvasive, static, external magnetic field  

NASA Astrophysics Data System (ADS)

One of the greatest challenges of nanoparticle cancer therapy is the delivery of adequate numbers of nanoparticles to the tumor site. Iron oxide nanoparticles (IONPs) have many favorable qualities, including their nontoxic composition, the wide range of diameters in which they can be produced, the cell-specific cytotoxic heating that results from their absorption of energy from a nontoxic, external alternating magnetic field (AMF), and the wide variety of functional coatings that can be applied. Although IONPs can be delivered via an intra-tumoral injection to some tumors, the resulting tumor IONP distribution is generally inadequate; additionally, local tumor injections do not allow for the treatment of systemic or multifocal disease. Consequently, the ultimate success of nanoparticle based cancer therapy likely rests with successful systemic, tumor-targeted IONP delivery. In this study, we used a surface-based, bilateral, noninvasive static magnetic field gradient produced by neodymiumboron- iron magnets (80 T/m to 130 T/m in central plane between magnets), a rabbit ear model, and systemicallydelivered starch-coated 100 nm magnetic (iron oxide) nanoparticles to demonstrate a spatially-defined increase in the local tissue accumulation of IONPs. In this non-tumor model, the IONPs remained within the local vascular space. It is anticipated that this technique can be used to enhance IONP delivery significantly to the tumor parenchyma/cells.

Zulauf, Grayson D.; Trembly, B. Stuart; Giustini, Andrew J.; Flint, Brian R.; Strawbridge, Rendall R.; Hoopes, P. Jack

2013-02-01

203

Magnetic nanoparticle assembly arrays prepared by hierarchical self-assembly on a patterned surface  

NASA Astrophysics Data System (ADS)

Inverted pyramid hole arrays were fabricated by photolithography and used as templates to direct the growth of colloidal nanoparticle assemblies. Cobalt ferrite nanoparticles deposit in the holes to yield high quality pyramid magnetic nanoparticle assembly arrays by carefully controlling the evaporation of the carrier fluid. Magnetic measurements indicate that the pyramid magnetic nanoparticle assembly arrays preferentially magnetize perpendicular to the substrate.Inverted pyramid hole arrays were fabricated by photolithography and used as templates to direct the growth of colloidal nanoparticle assemblies. Cobalt ferrite nanoparticles deposit in the holes to yield high quality pyramid magnetic nanoparticle assembly arrays by carefully controlling the evaporation of the carrier fluid. Magnetic measurements indicate that the pyramid magnetic nanoparticle assembly arrays preferentially magnetize perpendicular to the substrate. Electronic supplementary information (ESI) available: Experimental methods and characterization, a TEM image of cobalt ferrite nanoparticles, SEM images of cobalt ferrite nanoparticle crystals on IPHA formed by fast evaporation and slow pulling out from nanoparticle solution by using a dip coater, a SEM image of a partially filled inverted pyramid hole. See DOI: 10.1039/c4nr07489k

Wen, Tianlong; Zhang, Dainan; Wen, Qiye; Zhang, Huaiwu; Liao, Yulong; Li, Qiang; Yang, Qinghui; Bai, Feiming; Zhong, Zhiyong

2015-03-01

204

GMR sensors and magnetic nanoparticles for immuno-chromatographic assays  

NASA Astrophysics Data System (ADS)

Conventional tests based on immunorecognition and on the use of coloured colloidal particles have still some drawbacks that limit their use: they do not provide a quantitative determination of the analyte, and their sensitivity is limited. Our strategy to overcome these disadvantages consists in the use of superparamagnetic core-shell nanoparticles to tag the analyte. The use of these magnetic labels allows us to quantify the amount of analyte present in our sample with a very high sensitivity, detecting their magnetic response by means of the suitable magnetic sensor. Our method is based on measuring the magnetoresistive response of a spin-valve giant magnetoresistive (GMR) sensor placed in proximity to the magnetic nanoparticles present in the lateral flow strip. Here, a brief description of our prototype and of the measurement procedure will be presented, as well as preliminary assays using our biosensor to detect the hCG pregnancy hormone in a solution. A crucial aspect to take into account in order to increase the sensitivity is the proper functionalisation of the nanoparticle shell, in order to achieve an oriented immobilisation of the antibodies to be used in the immunorecognition process. Several strategies to further increase the sensor sensitivity are suggested.

Marquina, C.; de Teresa, J. M.; Serrate, D.; Marzo, J.; Cardoso, F. A.; Saurel, D.; Cardoso, S.; Freitas, P. P.; Ibarra, M. R.

2012-10-01

205

Real time monitoring of superparamagnetic nanoparticle self-assembly on surfaces of magnetic recording media  

SciTech Connect

Nanoparticle self-assembly dynamics are monitored in real-time by detecting optical diffraction from an all-nanoparticle grating as it self-assembles on a grating pattern recorded on a magnetic medium. The diffraction efficiency strongly depends on concentration, pH, and colloidal stability of nanoparticle suspensions, demonstrating the nanoparticle self-assembly process is highly tunable. This metrology could provide an alternative for detecting nanoparticle properties such as colloidal stability.

Ye, L.; Pearson, T.; Crawford, T. M., E-mail: crawftm@mailbox.sc.edu [Department of Physics and Astronomy, University of South Carolina, 712 Main Street, Columbia, South Carolina 29208 (United States); Qi, B.; Cordeau, Y.; Mefford, O. T. [Department of Materials Science and Engineering, Clemson University, 161 Sirrine Hall, Clemson, South Carolina 29634 (United States); Center for Optical Materials Science and Engineering Technologies (COMSET), 91 Technology Dr., Anderson, South Carolina 29625 (United States)

2014-05-07

206

Polarized neutron reflectivity from monolayers of self-assembled magnetic nanoparticles.  

PubMed

We prepared monolayers of iron oxide nanoparticles via self-assembly on a bare silicon wafer and on a vanadium film sputter deposited onto a plane sapphire substrate. The magnetic configuration of nanoparticles in such a dense assembly was investigated by polarized neutron reflectivity. A theoretical model fit shows that the magnetic moments of nanoparticles form quasi domain-like configurations at remanence. This is attributed to the dipolar coupling amongst the nanoparticles. PMID:25765283

Mishra, D; Petracic, O; Devishvili, A; Theis-Bröhl, K; Toperverg, B P; Zabel, H

2015-04-10

207

Polarized neutron reflectivity from monolayers of self-assembled magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

We prepared monolayers of iron oxide nanoparticles via self-assembly on a bare silicon wafer and on a vanadium film sputter deposited onto a plane sapphire substrate. The magnetic configuration of nanoparticles in such a dense assembly was investigated by polarized neutron reflectivity. A theoretical model fit shows that the magnetic moments of nanoparticles form quasi domain-like configurations at remanence. This is attributed to the dipolar coupling amongst the nanoparticles.

Mishra, D.; Petracic, O.; Devishvili, A.; Theis-Bröhl, K.; Toperverg, B. P.; Zabel, H.

2015-04-01

208

Experimental and theoretical investigation of cubic FeCo nanoparticles for magnetic hyperthermia  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles have great potential as heating elements for use in magnetic hyperthermia for cancer therapy and drug release. A problem with widely used magnetite and mag-hematite nanoparticles is the relatively low magnetization, which results in low heating efficiency. Here high-magnetic-moment Fe70Co30 nanoparticles with a cubic shape were synthesized using a gas condensation sputtering technique for potential magnetic hyperthermia application. The mean size of nanoparticles was 12 nm with 13.6% standard deviation. Micromagnetic simulation of particles' experimental hysteresis loop suggests that their behavior is dominated by a uniaxial anisotropy.

Jing, Ying; Sohn, Hweerin; Kline, Timothy; Victora, Randall H.; Wang, Jian-Ping

2009-04-01

209

Estimation of Magnetic NanoParticles' Size Distribution using a Magnetization Curve  

Microsoft Academic Search

This paper illustrates a method of reconstructing the size distribution of magnetic nano-particles (MNP) using a magnetization curve measured on a water-based MNP. To obtain the size distribution function, the solution of the integral equation describing fine particle magnetization in an external field must be found, without any a priori assumptions on the shape of size distribution p(d). From an

W. LIU; M. ZHOU; J. CHENG; L. KONG

210

Biomimetic control over size, shape and aggregation in magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetite (Fe3O4) is a widespread magnetic iron oxide encountered in both geological and biomineralizing systems, which also has many technological applications, e.g. in ferrofluids, inks, magnetic data storage materials and as contrast agents in magnetic resonance imaging. As its magnetic properties depend largely on the size and shape of the crystals, control over crystal morphology is an important aspect in the application of magnetite nanoparticles, both in biology and synthetic systems. Indeed, in nature organisms such as magnetotactic bacteria demonstrate a precise control over the magnetite crystal morphology, resulting in uniform and monodisperse nanoparticles. The magnetite formation in these bacteria is believed to occur through the co-precipitation of Fe(II) and Fe(III) ions, which is also the most widely applied synthetic route in industry. Synthetic strategies to magnetite with controlled size and shape exist, but involve high temperatures and rather harsh chemical conditions. However, synthesis via co-precipitation generally yields poor control over the morphology and therefore over the magnetic properties of the obtained crystals. Here we demonstrate that by tuning the reaction kinetics we can achieve biomimetic control over the size and shape of magnetite crystals but also over their organization in solution as well as their magnetic properties. We employ amino acids-based polymers to direct the formation of magnetite in aqueous media at room temperature via both the co-precipitation and the partial oxidation method. By using 2D and 3D (cryo)TEM it is shown that acidic amino acid monomers are most effective in affecting the magnetite particle morphology. By changing the composition of the polymers we can tune the morphology, the dispersibility as well as the magnetic properties of these nanoparticles.

Sommerdijk, Nico

2013-03-01

211

Magnetic characterization of surface-coated magnetic nanoparticles for biomedical application  

Microsoft Academic Search

The influence of the oleic acid surface coating on Fe3O4 and NiFe2O4 nanoparticles on their magnetic and calorimetric characterization was investigated. Fe3O4 nanoparticles (particle sizes of 15–20 and 20–30nm) and NiFe2O4 nanoparticles (particle sizes of 20–30nm) were dispersed in oleic acid. The surface coating resulted in a decrease in the dipole–dipole interaction between the particles, which in turn affected the

Asahi Tomitaka; Tomohiro Koshi; Shinsuke Hatsugai; Tsutomu Yamada; Yasushi Takemura

2011-01-01

212

Self-assembly of magnetic biofunctional nanoparticles  

NASA Astrophysics Data System (ADS)

Spherical, ferromagnetic FePt nanoparticles with a particle size of 3 nm were prepared by the simultaneous polyol reduction of Fe(acac)3 and Pt(acac)2 in phenyl ether in the presence of oleic acid and oleylamine. The oleic acid ligands can be replaced with 11-mercaptoundecanoic acid, giving particles that can be dispersed in water. Both x-ray diffraction and transmission electron microscopy indicated that FePt particles were not affected by ligands replacement. Dispersions of the FePt particles with 11-mercaptoundecanoic acid ligands and ammonium counter ions gave self-assembled films consisting of highly ordered hexagonal arrays of particles.

Sun, Xiangcheng; Thode, C. J.; Mabry, J. K.; Harrell, J. W.; Nikles, D. E.; Sun, K.; Wang, L. M.

2005-05-01

213

Using polymers to make up magnetic nanoparticles for biomedicine.  

PubMed

The use of magnetic nanoparitilces for biological and biomedical applications such as protein separation, targeted drug delivery, hyperthermia treatment, use as contrast agents of magnetic resonance imaging, biosensing, magnetic fluids environmental remediation is one of the most attractive fields of nanotechnology today because of their unique magnetic properties and the potential to function at cellular and molecular level of biological interactions. To apply them in biological fluids or aqueous environment it is essential to modulate the chemical nature of magnetic nanoparticle surfaces to increase their water solubility and colloidal stability in aqueous medium. By employing different coating technologies they cannot only be rendered longterm stable in biological fluids but also functionalized to fulfill different tasks, like molecular targeting or linking of therapeutic agents. To achieve this goal different polymeric coatings are applied to provide solubility and stability in aqueous solution and additional functional groups for attachment. Taken together the versatile modifications described in this review improved the ability to specifically tailor the features and properties of magnetic nanoparticles for biomedical applications. PMID:20201227

Chanana, Munish; Mao, Zhengwei; Wang, Dayang

2009-12-01

214

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

215

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

216

Biodistribution of PAMAM dendrimer conjugated magnetic nanoparticles in mice.  

PubMed

Fluorescein-loaded magnetic nanoparticles (FMNPs) have been increasingly utilized in nanomedicine due to their unique properties. In this study, polyamidoamine (PAMAM) dendrimer was used to modify the FMNPs through bifunctional polyethylene glycol linker. The obtained PAMAM modified magnetic nanoparticles (PFMNPs) were characterized by transmission electron microscope, thermogravimetric analysis, zeta potential titration, and fourier transform infrared spectroscopy. The effect of PAMAM conjugation on the biodistribution of FMNPs and PFMNPs were investigated by confocal laser scanning microscopy and inductively coupled plasma atomic emission spectrometry, respectively. It was revealed that PAMAM conjugation resulted in a lower uptake of FMNPs in the lung and less aggregation in the liver, whereas a higher uptake in brain and testis. Furthermore, the serum biochemical and the hematological analysis indicated the PFMNPs caused no significant changes in enzymes reflective of inflammatory response or organ toxicity. PMID:24276671

Zhao, Huanying; Gu, Wei; Ye, Ling; Yang, Hui

2014-03-01

217

Magnetic nanoparticle-supported lipid bilayers for drug delivery.  

PubMed

Magnetic nanoparticle-supported lipid bilayers (SLBs) constructed around core-shell Fe3O4-SiO2 nanoparticles (SNPs) were prepared and evaluated as potential drug carriers. We describe how an oxime ether lipid can be mixed with SNPs to produce lipid-particle assemblies with highly positive ? potential. To demonstrate the potential of the resultant cationic SLBs, the particles were loaded with either the anticancer drug doxorubicin or an amphiphilic analogue, prepared to facilitate integration into the supported lipid bilayer, and then examined in studies against MCF-7 breast cancer cells. The assemblies were rapidly internalized and exhibited higher toxicity than treatments with doxorubicin alone. The magnetic SLBs were also shown to increase the efficacy of unmodified doxorubicin. PMID:25714501

Mattingly, Stephanie J; O'Toole, Martin G; James, Kurtis T; Clark, Geoffrey J; Nantz, Michael H

2015-03-24

218

Characterization of magnetic nanoparticle by dynamic light scattering  

PubMed Central

Here we provide a complete review on the use of dynamic light scattering (DLS) to study the size distribution and colloidal stability of magnetic nanoparticles (MNPs). The mathematical analysis involved in obtaining size information from the correlation function and the calculation of Z-average are introduced. Contributions from various variables, such as surface coating, size differences, and concentration of particles, are elaborated within the context of measurement data. Comparison with other sizing techniques, such as transmission electron microscopy and dark-field microscopy, revealed both the advantages and disadvantages of DLS in measuring the size of magnetic nanoparticles. The self-assembly process of MNP with anisotropic structure can also be monitored effectively by DLS. PMID:24011350

2013-01-01

219

Complex of heavy magnetic ions and luminescent silicon nanoparticles  

NASA Astrophysics Data System (ADS)

We study the optical properties of luminescent silicon nanoparticles in the presence of magnetic ions of iron or erbium under wet conditions and electric biasing. Upon the introduction of the ions under zero biasing, the brightness is enhanced with some spectral change. Under biasing including breakdown field conditions, the enhancement remains stable and is maintained after recovery of the particles into nanosolid films using electric spray. The ion-nanoparticle interaction is analyzed using first principle atomistic calculations employing unrestricted Hartree-Fock density functional theory. The calculations yield configurations, which show strong binding and stability. The complexes promise diverse applications in magnetic/optical imaging, spatially programmable deposition, spin-based memories and transistors, infrared communications, filtration, as well as interplanetary and interstellar observation and modeling.

Hoang, T.; Stupca, M.; Mantey, K.; Maximenko, Y.; Elhalawany, N.; Carr, C.; Yu, H.; Nayfeh, M. H.; Morgan, H.

2013-10-01

220

Preparation and characterization of magnetic nanoparticles coated with polyethylene glycol  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles Fe3O4 were prepared in air environment by the coprecipitation method using molar ratios of Fe2+: Fe3+ = 1: 2. The surface of magnetic nanoparticles was coated with sodium oleate as the primary layer and polyethylene glycol 6000 (PEG-6000) as the second layer. The morphology of the particles was investigated by scanning electronic microscopy (SEM). X-ray diffraction (XRD) indicated the sole existence of inverse cubic spinel phase of Fe3O4 and an average size of about 25 nm. Fourier transform infrared spectroscopy (FTIR) analysis indicated existence of two distinct surfactants on the particle surface. In addition, the results of FT-IR indicated that the coated Fe3O4 particles improved the thermal stability due to the interaction between the Fe3O4 particles and protective layers.

Hoa, Le Thi Mai; Thi Dung, Tran; Mau Danh, Tran; Duc, Nguyen Huu; Mau Chien, Dang

2009-09-01

221

Magnetic nanoparticles for MR imaging: agents, techniques and cardiovascular applications  

Microsoft Academic Search

Magnetic nanoparticles (MNP) are playing an increasingly important role in cardiovascular molecular imaging. These agents\\u000a are superparamagnetic and consist of a central core of iron-oxide surrounded by a carbohydrate or polymer coat. The size,\\u000a physical properties and pharmacokinetics of MNP make them highly suited to cellular and molecular imaging of atherosclerotic\\u000a plaque and myocardial injury. MNP have a sensitivity in

David E. Sosnovik; Matthias Nahrendorf; Ralph Weissleder

2008-01-01

222

Size-controlled magnetic nanoparticles with lecithin for biomedical applications  

NASA Astrophysics Data System (ADS)

Lecithin-adsorbed magnetic nanoparticles were prepared by three-step process that the thermal decomposition was combined with ultrasonication. Experimental parameters were three items—molar ratio between Fe(CO) 5 and oleic acid, keeping time at decomposition temperature and lecithin concentration. As the molar ratio between Fe(CO) 5 and oleic acid, and keeping time at decomposition temperature increased, the particle size increased. However, the change of lecithin concentration did not show the remarkable particle size variation.

Park, S. I.; Kim, J. H.; Kim, C. G.; Kim, C. O.

2007-05-01

223

Heterogeneous distribution of magnetic nanoparticles in reactive polymer blends  

Microsoft Academic Search

This work attempts to study the influence of a reactive compatibilizer on the uneven distribution of Fe3O4 nanoparticles in polystyrene (PS)\\/polyamide 6 (PA6) blends and to present a novel, low-cost approach for fabricating PA6-based magnetic microspheres. By adding terminal maleic anhydride functionalized PS (FPS), we were able to observe significant reductions in both the PA6 domain size and its polydispersity

Guozhang Wu; Xiaoxia Cai; Xiaojie Lin; Hiroshi Yui

2010-01-01

224

A magnetic poly(dimethylesiloxane) composite membrane incorporated with uniformly dispersed, coated iron oxide nanoparticles  

Microsoft Academic Search

We report a new magnetic polymer membrane for MEMS application. The polymeric magnetic composite has coated iron oxide nanoparticles incorporated in a polydimethylsiloxane (PDMS) matrix. Existing magnetic polymeric materials have particle agglomeration problems, which result in rough surfaces and uneven mechanical and optical properties. We show that the use of iron oxide nanoparticles (10 nm in diameter) with fatty acid

Luna Cheng; Mu Chiao

2010-01-01

225

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

226

Parallel algorithm for mass transfer simulations of weakly-magnetic nanoparticles  

Microsoft Academic Search

We present a parallel algorithm for the simulation of mass transfer of weakly-magnetic nanoparticles in high gradient magnetic separation. The transport phenomena of weakly-magnetic nanoparticles in regions around a ferromagnetic long cylindrical wire in static fluid is considered. The normalized continuity equations describing the dynamics of particle volume concentration are solved numerically by using finite difference method. Parallel simulation is

Kanok Hournkumnuard; Chantana Phongpensri

2009-01-01

227

Surfactant Organic Molecules Restore Magnetism in Metal-Oxide Nanoparticle Surfaces  

E-print Network

Surfactant Organic Molecules Restore Magnetism in Metal-Oxide Nanoparticle Surfaces Juan Salafranca, Nashville, Tennessee 37235, United States *S Supporting Information ABSTRACT: The properties of magnetic nanoparticles tend to be depressed by the unavoidable presence of a magnetically inactive surface layer. However

Pennycook, Steve

228

Effect of high AC magnetic field on magnetic nanoparticles for magnetic hyperthermia and radiation\\/chemotherapy applications  

Microsoft Academic Search

Particularly for applications such as radiation therapy and chemotherapy, magnetically induced heating, or magnetic hyperthermia, is of great importance. This study presents a relatively simple setup that generates controlled and constant heating temperatures of 47C and 53C, well in excess of required temperatures for mild hyperthermia (42C). The heating elements used are superparamagnetic nanoparticles with Curie temperature of 47C and

D. Belc; Y. Haik; C. J. Chen; R. Roberts; R. Arora

2004-01-01

229

Magnetic polyorganosiloxane core-shell nanoparticles: Synthesis, characterization and magnetic fractionation  

NASA Astrophysics Data System (ADS)

AbstactHere, we present the synthesis, characterization and magnetic separation of magnetic polyorganosiloxane nanoparticles. Magnetic iron oxide nanoparticles with average particle radii of 3.2 nm had been synthesized by a simple coprecipitation process of iron(II) and iron(III) salt in basic solution. Afterwards, the particles were successfully incorporated into a polyorganosiloxane network via a polycondensation reaction of trimethoxymethylsilane (T), diethoxydimethylsilane (D) and the functional monomer (chloromethylphenyl)trimethoxysilane (ClBz-T) in aqueous dispersion. A core-shell system was chosen to increase the flexibility of the system concerning size, composition and functionalization possibilities. The magnetic nanocapsules with particle radii below 60 nm were separated from non-magnetic material with a high effectiveness by the use of commercially available separation columns which are commonly used for isolation of microbeads and subsequently characterized via transmission electron microscopy (TEM), asymmetrical flow field-flow fractionation (AF-FFF), superconducting quantum interference device (SQUID) and Mössbauer spectroscopy.

Utech, Stefanie; Scherer, Christian; Krohne, Korinna; Carrella, Luca; Rentschler, Eva; Gasi, Teuta; Ksenofontov, Vadim; Felser, Claudia; Maskos, Michael

2010-11-01

230

Measuring and controlling the transport of magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Despite the large body of literature describing the synthesis of magnetic nanoparticles, few analytical tools are commonly used for their purification and analysis. Due to their unique physical and chemical properties, magnetic nanoparticles are appealing candidates for biomedical applications and analytical separations. Yet in the absence of methods for assessing and assuring their purity, the ultimate use of magnetic particles and heterostructures is likely to be limited. For magnetic nanoparticles, it is the use of an applied magnetic flux or field gradient that enables separations. Flow based techniques are combined with applied magnetic fields to give methods such as magnetic field flow fractionation and high gradient magnetic separation. Additional techniques have been explored for manipulating particles in microfluidic channels and in mesoporous membranes. This thesis further describes development of these and new analytical tools for separation and analysis of colloidal particles is critically important to enable the practical use of these, particularly for medicinal purposes. Measurement of transport of nanometer scale particles through porous media is important to begin to understand the potential environmental impacts of nanomaterials. Using a diffusion cell with two compartments separated by either a porous alumina or polycarbonate membrane as a model system, diffusive flux through mesoporous materials is examined. Experiments are performed as a function of particle size, pore diameter, and solvent, and the particle fluxes are monitored by the change in absorbance of the solution in the receiving cell. Using the measured extinction coefficient and change in absorbance of the solution as a function of time, the fluxes of 3, 8, and 14 nm diameter CoFe2O4 particles are determined as they are translocated across pores with diameters 30, 50, 100, and 200 nm in hexane and aqueous solutions. In general, flux decreases with increasing particle size and increases with pore diameter. We find that fluxes are faster in aqueous solutions than in hexane, which is attributed to the hydrophilic nature of the porous membranes and differences in wettability. The impact of an applied magnetic flux gradient, which induces magnetization and motion, on permeation is also examined. Surface chemistry plays an important role in determining flux through porous media such as in the environment. Diffusive flux of nanoparticles through alkylsilane modified porous alumina is measured as a model for understanding transport in porous media of differing surface chemistries. Experiments are performed as a function of particle size, pore diameter, attached hydrocarbon chain length and chain terminus, and solvent. Particle fluxes are monitored by the change in absorbance of the solution in the receiving side of a diffusion cell. In general, flux increases when the membranes are modified with alkylsilanes compared to untreated membranes, which is attributed to the hydrophobic nature of the porous membranes and differences in wettability. We find that flux decreases, in both hexane and aqueous solutions, when the hydrocarbon chain lining the interior pore wall increases in length. The rate and selectivity of transport across these membranes is related to the partition coefficient (Kp) and the diffusion coefficient (D) of the permeating species. By conducting experiments as a function of initial particle concentration, we find that KpD increases with increasing particle size, is greater in alkylsilane--modified pores, and larger in hexane solution than water. The impact of the alkylsilane terminus (--CH3, --Br, --NH2, --COOH) on permeation in water is also examined. In water, the highest KpD is observed when the membranes are modified with carboxylic acid terminated silanes and lowest with amine terminated silanes as a result of electrostatic effects during translocation. Finally, the manipulation of magnetic nanoparticles for the controlled formation of linked nanoparticle assemblies between microfluidic channels by the application of an external

Stephens, Jason R.

231

Functionalized Magnetic Nanoparticles as an In Vivo Delivery System  

NASA Astrophysics Data System (ADS)

We developed extremely small functionalized magnetic nanoparticles (MNPs) for use as an in vivo delivery system for pharmaceuticals and biomolecules. We functionalized the MNPs (d = 3 nm) by silanization of amino groups on the particles with (3-aminopropyl)triethoxysilane for subsequent cross-linking with pharmaceuticals and biomolecules. The MNPs were successfully introduced into living cells without any further modification, such as the use of cationic residues, to enhance endocytic internalization. The particles could be incorporated into the subcutaneous tissue of a mouse’s ear through the skin of the ear and could be localized by application of an external magnetic field.

Taira, Shu; Moritake, Shinji; Hatanaka, Takahiro; Ichiyanagi, Yuko; Setou, Mitsutoshi

232

Effects of coating on magnetic properties in iron oxide nanoparticles  

NASA Astrophysics Data System (ADS)

We have studied influence of surface modification on physical properties of iron oxide nanoparticles. We compared samples prepared by thermal decomposition of organic precursor in the presence of oleic acid, and the particles prepared by coprecipitation and partially coated by SiO2 or modified by citric acid and subsequently covered by photoactive TiO2 layer, respectively. Samples were characterised using TEM and XRD, further magnetic studies such as temperature dependence of magnetization and a.c. susceptibility show superparamagnetic behavior for all samples at room temperature. The effects of coating on dipolar inter particle interactions are discussed.

Bittova, B.; Poltierova-Vejpravova, J.; Roca, A. G.; Morales, M. P.; Tyrpekl, V.

2010-01-01

233

Magnetic nanoparticles-DNA interactions: design and applications of nanobiohybrid systems  

NASA Astrophysics Data System (ADS)

Mechanisms of interaction between nucleic acid molecules and magnetic nanoparticles and methods of their conjugation in order to develop functional nanostructures are considered. The properties of nucleic acids and magnetic nanoparticles that are key to the design of nanobiocomposites are described. Prospects for applications of nanobiocomposites in nanoelectronics and medicine are analyzed. Possible harmful effects of magnetic nanoparticles on the genetic system are briefly outlined. The bibliography includes 287 references.

Pershina, A. G.; Sazonov, A. E.; Filimonov, V. D.

2014-04-01

234

Magnetic properties of substituted strontium ferrite nanoparticles and thin films  

NASA Astrophysics Data System (ADS)

SrFe12-x(Zr0.5Mg0.5)xO19 nanoparticles and thin films with x=0-2.5 were synthesized by a sol-gel method on thermally oxidized silicon wafer (Si/SiO2). Structural and magnetic characteristics of synthesized samples were studied employing x-rays diffraction (XRD), transmission electron microscopy (TEM), magnetic susceptometer, atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), and vibrating sample magnetometer (VSM). TEM micrographs display that the narrow size distribution of ferrite nanoparticles with average particle size of 50 nm were fabricated. Fitting obtained data of effective magnetic susceptibility by Vogel-Fulcher law confirms the existence of strong magnetic interaction among fine particles. XRD patterns and FE-SEM micrographs demonstrated that single phase c-axis hexagonal ferrite films with rather narrow grain size distribution were obtained. AFM micrographs exhibited that the surface roughness increases with an increase in Zr-Mg content. It was found from the VSM graphs that with an increase in substitution contents the coercivity decreases, while the saturation of magnetization increases. The Henkle plots confirms the existence of exchange coupling among nano-grain in ferrite thin films.

Ghasemi, Ali

2012-04-01

235

Nanosized corners for trapping and detecting magnetic nanoparticles.  

PubMed

We present a device concept based on controlled micromagnetic configurations in a corner-shaped permalloy nanostructure terminated with two circular disks, specifically designed for the capture and detection of a small number of magnetic beads in suspension. A transverse head-to-head domain wall (TDW) placed at the corner of the structure plays the role of an attracting pole for magnetic beads. The TDW is annihilated in the terminating disks by applying an appropriate magnetic field, whose value is affected by the presence of beads chemically bound to the surface. In the case where the beads are not chemically bound to the surface, the annihilation of the TDW causes their release into the suspension. The variation of the voltage drop across the corner, due to the anisotropic magnetoresistance (AMR) while sweeping the magnetic field, is used to detect the presence of a chemically bound bead. The device response has been characterized by using both synthetic antiferromagnetic nanoparticles (disks of 70 nm diameter and 20 nm height) and magnetic nanobeads, for different thicknesses of the protective capping layer. We demonstrate the detection down to a single nanoparticle, therefore the device holds the potential for the localization and detection of small numbers of molecules immobilized on the particle's functionalized surface. PMID:19713593

Donolato, Marco; Gobbi, Marco; Vavassori, Paolo; Leone, Marco; Cantoni, Matteo; Metlushko, Vitali; Ilic, Bojan; Zhang, Mingliang; Wang, Shan X; Bertacco, Riccardo

2009-09-23

236

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

237

Magnetic nanoparticle drug delivery systems for targeting tumor  

NASA Astrophysics Data System (ADS)

Tumor hypoxia, or low oxygen concentration, is a result of disordered vasculature that lead to distinctive hypoxic microenvironments not found in normal tissues. Many traditional anti-cancer agents are not able to penetrate into these hypoxic zones, whereas, conventional cancer therapies that work by blocking cell division are not effective to treat tumors within hypoxic zones. Under these circumstances the use of magnetic nanoparticles as a drug delivering agent system under the influence of external magnetic field has received much attention, based on their simplicity, ease of preparation, and ability to tailor their properties for specific biological applications. Hence in this review article we have reviewed current magnetic drug delivery systems, along with their application and clinical status in the field of magnetic drug delivery.

Mody, Vicky V.; Cox, Arthur; Shah, Samit; Singh, Ajay; Bevins, Wesley; Parihar, Harish

2014-04-01

238

Efficient bacterial capture with amino acid modified magnetic nanoparticles.  

PubMed

Traditional chemical disinfectants are becoming increasingly defective due to the generation of carcinogenic disinfection byproducts and the emergence of antibiotic-resistant bacterial strains. Functionalized magnetic nanoparticles yet have shown great application potentials in water treatment processes especially for bacterial removal. In this study, three types of amino acids (arginine, lysine, and poly-l-lysine) functionalized Fe3O4 nanoparticles (Fe3O4@Arg, Fe3O4@Lys, and Fe3O4@PLL) were prepared through a facile and inexpensive two-step process. The amino acid modified Fe3O4 nanoparticles (Fe3O4@AA) showed rapid and efficient capture and removal properties for both Gram-positive Bacillus subtilis (B. subtilis) and Gram-negative Escherichia coli 15597 (E. coli). For both strains, more than 97% of bacteria (initial concentration of 1.5 × 10(7) CFU mL(-1)) could be captured by all three types of magnetic nanoparticles within 20 min. With E. coli as a model strain, Fe3O4@AA could remove more than 94% of cells from solutions over a broad pH range (from 4 to 10). Solution ionic strength did not affect cell capture efficiency. The co-presence of sulfate and nitrate in solutions did not affect the capture efficiency, whereas, the presence of phosphate and silicate slightly decreased the removal rate. However, around 90% and 80% of cells could be captured by Fe3O4@AA even at 10 mM of silicate and phosphate, respectively. Bacterial capture efficiencies were over 90% and 82% even in the present of 10 mg L(-1) of humic acid and alginate, respectively. Moreover, Fe3O4@AA nanoparticles exhibited good reusability, and greater than 90% of E. coli cells could be captured even in the fifth regeneration cycle. The results showed Fe3O4@AA fabricated in this study have great application potential for bacteria removal from water. PMID:24370656

Jin, Yinjia; Liu, Fei; Shan, Chao; Tong, Meiping; Hou, Yanglong

2014-03-01

239

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

NASA Astrophysics Data System (ADS)

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

Smolkova, Ilona S.; Kazantseva, Natalia E.; Babayan, Vladimir; Smolka, Petr; Parmar, Harshida; Vilcakova, Jarmila; Schneeweiss, Oldrich; Pizurova, Nadezda

2015-01-01

240

Mean first-passage times for an ac-driven magnetic moment of a nanoparticle  

E-print Network

The two-dimensional backward Fokker-Planck equation is used to calculate the mean first-passage times (MFPTs) of the magnetic moment of a nanoparticle driven by a rotating magnetic field. It is shown that a magnetic field that is rapidly rotating in the plane {\\it perpendicular} to the easy axis of the nanoparticle governs the MFPTs just in the same way as a static magnetic field that is applied {\\it along} the easy axis. Within this framework, the features of the magnetic relaxation and net magnetization of systems composed of ferromagnetic nanoparticles arising from the action of the rotating field are revealed.

S. I. Denisov; K. Sakmann; P. Talkner; P. Hänggi

2007-01-07

241

Reentrant paramagnetism induced by drastic reduction of magnetic couplings at surfaces of superparamagnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Superparamagnetism appears when the Néel-Brown relaxation time of magnetic nanoparticles is shorter than the measurement time. Recent experimental studies of different types of magnetic nanoparticles revealed the existence of another paramagnetic region below the standard blocking temperatures. Here we elucidate the microscopic origin of this reentrant paramagnetism using a phenomenological model, which exploits the effects of weaker magnetic coupling strengths at the surfaces of ultrasmall nanoparticles. Within this picture, we have calculated the total magnetization of various nanoparticle arrays upon both finite-field and zero-field cooling processes via detailed classical Monte Carlo simulations, and found that the appearance of the reentrant phenomena necessarily invokes a drastic reduction of the magnetic coupling strengths at the surfaces of the nanoparticles. Our predictions can be readily tested experimentally using a micro-SQUID, and is expected to be beneficial in further applications of superparamagnetic nanoparticles.

Qin, Wei; Li, Xiaoguang; Xie, Yi; Zhang, Zhenyu

2014-12-01

242

Monitoring the endocytosis of magnetic nanoparticles by cells using permanent micro-flux sources.  

PubMed

Trapping of cells is essential to perform basic handling operations in cell-based microsystems, such as media exchange, concentration, cell isolation and cell sorting. Cell trapping by magnetophoresis typically requires cell labeling with magnetic nanoparticles. Here we report on endocytotic uptake of 100 nm magnetic nanoparticles by Human Embryonic Kidney 293 cells. The attraction of labeled cells by micro-magnet arrays characterised by very high magnetic field gradients (?10? T/m) was studied as a function of labeling conditions (nanoparticle concentration in the extracellular medium, incubation time). The threshold incubation conditions for effective magnetophoretic trapping were established. This simple technique may be exploited to minimise the quantity of magnetic nanoparticles needed for efficient cell trapping, thus reducing stress or nanoparticle-mediated toxicity. Nanoparticle internalization into cells was confirmed using both confocal and Transmission Electron Microscopy (TEM). PMID:22773161

Osman, O; Zanini, L F; Frénéa-Robin, M; Dumas-Bouchiat, F; Dempsey, N M; Reyne, G; Buret, F; Haddour, N

2012-10-01

243

Enhanced magnetic properties in antiferromagnetic-core/ferrimagnetic-shell nanoparticles.  

PubMed

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

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

2015-01-01

244

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

PubMed Central

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

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

2015-01-01

245

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

246

Size-dependent magnetic properties of iron carbide nanoparticles embedded in a carbon matrix  

Microsoft Academic Search

Here we report on the magnetic properties of iron carbide nanoparticles embedded in a carbon matrix. Granular distributions of nanoparticles in an inert matrix, of potential use in various applications, were prepared by pyrolysis of organic precursors using the thermally assisted chemical vapour deposition method. By varying the precursor concentration and preparation temperature, compositions with varying iron concentration and nanoparticle

E. P. Sajitha; V. Prasad; S. V. Subramanyam; Ajay Kumar Mishra; Subhajit Sarkar; Chandrahaas Bansal

2007-01-01

247

Swelling enhanced remanent magnetization of hydrogels cross-linked with magnetic nanoparticles.  

PubMed

Hydrogels that are pH-sensitive and partially cross-linked by cobalt ferrite nanoparticles exhibit remarkable remanent magnetization behavior. The magnetic fields measured outside our thin disks of ferrogel are weak, but in the steady state, the field dependence on the magnetic content of the gels and the measurement geometry is as expected from theory. In contrast, the time-dependent behavior is surprisingly complicated. During swelling, the remanent field first rapidly increases and then slowly decreases. We ascribe the swelling-induced field enhancement to a change in the average orientation of magnetic dipolar structures, while the subsequent field drop is due to the decreasing concentration of nanoparticles. During shrinking, the field exhibits a much weaker time dependence that does not mirror the values found during swelling. These observations provide original new evidence for the markedly different spatial profiles of the pH during swelling and shrinking of hydrogels. PMID:25485553

van Berkum, Susanne; Biewenga, Pieter D; Verkleij, Suzanna P; van Zon, J Hans B A; Boere, Kristel W M; Pal, Antara; Philipse, Albert P; Erné, Ben H

2015-01-13

248

Particle size and magnetic field-induced optical properties of magnetic fluid nanoparticles.  

PubMed

Magnetite nanoparticles with diameters of 7, 9, and 12 nm have been prepared by a chemical coprecipitation method. The transmission of light through magnetic fluid containing these nanoparticles has been investigated as a function of film thickness with wavelength between 400 and 750 nm, and applied magnetic fields up to 275 Oe. The transmission threshold shifts to the lower wavelength side with decreasing magnetic fluid film thickness as well as the particle size. For a given film thickness, the transmittance increases with increasing magnetic field for films with a particle size of 7 and 9 nm, but decreases in the 12-nm film. This is attributed to the competition between the van der Waals and dipole-dipole interaction. PMID:16241436

Rao, G Narsinga; Yao, Y D; Chen, Y L; Wu, K T; Chen, J W

2005-09-01

249

Magnetic Nanoparticles and microNMR for Diagnostic Applications  

PubMed Central

Sensitive and quantitative measurements of clinically relevant protein biomarkers, pathogens and cells in biological samples would be invaluable for disease diagnosis, monitoring of malignancy, and for evaluating therapy efficacy. Biosensing strategies using magnetic nanoparticles (MNPs) have recently received considerable attention, since they offer unique advantages over traditional detection methods. Specifically, because biological samples have negligible magnetic background, MNPs can be used to obtain highly sensitive measurements in minimally processed samples. This review focuses on the use of MNPs for in vitro detection of cellular biomarkers based on nuclear magnetic resonance (NMR) effects. This detection platform, termed diagnostic magnetic resonance (DMR), exploits MNPs as proximity sensors to modulate the spin-spin relaxation time of water molecules surrounding the molecularly-targeted nanoparticles. With new developments such as more effective MNP biosensors, advanced conjugational strategies, and highly sensitive miniaturized NMR systems, the DMR detection capabilities have been considerably improved. These developments have also enabled parallel and rapid measurements from small sample volumes and on a wide range of targets, including whole cells, proteins, DNA/mRNA, metabolites, drugs, viruses and bacteria. The DMR platform thus makes a robust and easy-to-use sensor system with broad applications in biomedicine, as well as clinical utility in point-of-care settings. PMID:22272219

Shao, Huilin; Min, Changwook; Issadore, David; Liong, Monty; Yoon, Tae-Jong; Weissleder, Ralph; Lee, Hakho

2012-01-01

250

Magnetic metal nanoparticles coated polyacrylonitrile textiles as microwave absorber  

NASA Astrophysics Data System (ADS)

Polyacrylonitrile (PAN) textiles with 2 mm thickness are coated with magnetic nanoparticles in coating baths with Ni, Co and their alloys via an electroless metal deposition method. The crystal structure, morphology and magnetic nature of composites are investigated by X-ray Powder diffraction, Scanning Electron Microscopy, and dc magnetization measurement techniques. The frequency dependent microwave absorption measurements have been carried out in the frequency range of 12.4-18 GHz (X and P bands). Diamagnetic and ferromagnetic properties are also investigated. Finally, the microwave absorption of composites is found strongly dependent on the coating time. One absorption peak is observed between 14.3 and 15.8 GHz with an efficient absorption bandwidth of 3.3-4.1 GHz (under -20 dB reflection loss limit). The Reflection loss (RL) can be achieved between -30 and -50 dB. It was found that the RL is decreasing and absorption bandwidth is decreasing with increasing coating time. While absorption peak moves to lower frequencies in Ni coated PAN textile, it goes higher frequencies in Co coated ones. The Ni-Co alloy coated composites have fluctuating curve of absorption frequency with respect to coating time. These results encourage further development of magnetic nanoparticle coated textile absorbers for broadband applications.

Akman, O.; Kavas, H.; Baykal, A.; Toprak, M. S.; Çoruh, Ali; Akta?, B.

2013-02-01

251

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. PMID:25301993

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

2014-01-01

252

Magnetic and Non-Magnetic Nanoparticles from a Group of Uniform Materials Based on Organic Salts  

PubMed Central

The size and uniformity of magnetic nanoparticles developed from a Group of Uniform Materials Based on Organic Salts (GUMBOS) were controlled using an in situ ion exchange, water-in-oil (w/o) microemulsion preparation. Most of these nanoGUMBOS are in fact ionic liquids (i.e., melting points less than 100 °C), while others have melting points above the conventional 100 °C demarcation. Simple variations in the reagent concentrations following a w/o approach allowed us to smoothly and predictably vary nanoparticle dimensions across a significant size regime with excellent uniformity. Average sizes of GUMBOS ranging from 14 to 198 nm were achieved by manipulation of the reagent concentration for example. Controllable formation of this new breed of nanoparticles is important for numerous potential applications and will open up interesting new opportunities in drug delivery, magnetic resonance imaging, and protein separations, among other areas. PMID:19780529

Tesfai, Aaron; El-Zahab, Bilal; Kelley, Algernon T.; Li, Min; Garno, Jayne C.; Baker, Gary A.; Warner, Isiah M.

2009-01-01

253

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

254

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

255

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

PubMed Central

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. PMID:24910569

2014-01-01

256

Imaging of Her2-Targeted Magnetic Nanoparticles for Breast Cancer Detection: Comparison of SQUID-detected Magnetic Relaxometry and MRI  

PubMed Central

Both magnetic relaxometry and magnetic resonance imaging (MRI) can be used to detect and locate targeted magnetic nanoparticles, non-invasively and without ionizing radiation. Magnetic relaxometry offers advantages in terms of its specificity (only nanoparticles are detected) and the linear dependence of the relaxometry signal on the number of nanoparticles present. In this study, detection of single-core iron oxide nanoparticles by Superconducting Quantum Interference Device (SQUID)-detected magnetic relaxometry and standard 4.7 T MRI are compared. The nanoparticles were conjugated to a Her2 monoclonal antibody and targeted to Her2-expressing MCF7/Her2-18 breast cancer cells); binding of the nanoparticles to the cells was assessed by magnetic relaxometry and iron assay. The same nanoparticle-labeled cells, serially diluted, were used to assess the detection limits and MR relaxivities. The detection limit of magnetic relaxometry was 125,000 nanoparticle-labeled cells at 3 cm from the SQUID sensors. T2-weighted MRI yielded a detection limit of 15,600 cells in a 150 ?l volume, with r1 = 1.1 mM?1s?1 and r2 = 166 mM?1s?1. Her2-targeted nanoparticles were directly injected into xenograft MCF7/Her2-18 tumors in nude mice, and magnetic relaxometry imaging and 4.7 T MRI were performed, enabling direct comparison of the two techniques. Co-registration of relaxometry images and MRI of mice resulted in good agreement. A method for obtaining accurate quantification of microgram quantities of iron in the tumors and liver by relaxometry was also demonstrated. These results demonstrate the potential of SQUID-detected magnetic relaxometry imaging for the specific detection of breast cancer and the monitoring of magnetic nanoparticle-based therapies. PMID:22539401

Adolphi, Natalie L.; Butler, Kimberly S.; Lovato, Debbie M.; Tessier, T. E.; Trujillo, Jason E.; Hathaway, Helen J.; Fegan, Danielle L.; Monson, Todd C.; Stevens, Tyler E.; Huber, Dale L.; Ramu, Jaivijay; Milne, Michelle L.; Altobelli, Stephen A.; Bryant, Howard C.; Larson, Richard S.; Flynn, Edward R.

2013-01-01

257

Magnetic Properties of Ubiquitous yet Underrated Antiferromagnetic Nanoparticles  

NASA Astrophysics Data System (ADS)

Ferrihydrite, lepidocrocite and goethite are antiferromagnetic, weakly "ferromagnetic" iron oxyhydroxides that are commonly found in diverse environments, including ground waters and streams, sediments, soils, or acid mine drainage. One of them, ferrihydrite, constitutes the mineral core of ferritin, a vital iron storage protein. Iron oxyhydroxides take part in multiple biological and abiological processes, and can evolve, under changing environmental or geological conditions, to more magnetic phases such as hematite, maghemite, or magnetite. Therefore, they represent key minerals with regard to paleoclimate, paleoenvironmental, and paleomagnetic studies. We will present low temperature magnetic properties acquired on fully characterized synthetic iron oxyhydroxides. The complex nature of the magnetism of these minerals is revealed by comparing magnetic data with other types of characterizations such as high-resolution transmission electron microscopy or synchrotron X-ray magnetic circular dichroism (XMCD), or when the early-stages of solid-state alteration (under oxidizing or reducing atmosphere) are studied. In particular, we will present resent results about the structure of 6-line ferrihydrite, about the possible presence of ferri-magnetic nano-clusters in lepidocrocite, and about uncompensated magnetic moments in goethite nanoparticles.

Guyodo, Y. J.; Till, J. L.; Lagroix, F.; Bonville, P.; Penn, R.; Sainctavit, P.; Ona-Nguema, G.; Morin, G.

2013-05-01

258

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

259

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

Microsoft Academic Search

Magnetometry was used to determine the magnetic properties of maghemite (?-Fe2O3) nanoparticles formed within Listeria innocua protein cage. The electron magnetic resonance spectrum shows the presence of at least two magnetization components. The magnetization curves are explained by a sum of two Langevin functions in which each filled protein cage contains both a large magnetic iron oxide core plus an

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

2010-01-01

260

Large magnetic anisotropy in ferrihydrite nanoparticles synthesized from reverse micelles  

NASA Astrophysics Data System (ADS)

Six-line ferrihydrite (FH) nanoparticles have been synthesized in the core of reverse micelles, used as nanoreactors to obtain average particle sizes \\langle d\\rangle \\approx 2 \\mbox {--} 4~\\mathrm {nm} . The blocking temperatures TBm extracted from magnetization data increased from ap10 to 20 K for increasing particle size. Low-temperature Mössbauer measurements allowed us to observe the onset of differentiated contributions from the particle core and surface as the particle size increases. The magnetic properties measured in the liquid state of the original emulsion showed that the ferrihydrite phase is not present in the liquid precursor, but precipitates in the micelle cores after the free water is freeze-dried. Systematic susceptibility ?ac(f,T) measurements showed the dependence of the effective magnetic anisotropy energies Ea with particle volume, and yielded an effective anisotropy value of Keff = 312 ± 10 kJ m-3.

Duarte, E. L.; Itri, R.; Lima, E., Jr.; Baptista, M. S.; Berquó, T. S.; Goya, G. F.

2006-11-01

261

Evaluation of Hyperthermia of Magnetic Nanoparticles by Dehydrating DNA  

PubMed Central

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

262

Bench-to-bedside translation of magnetic nanoparticles  

PubMed Central

Magnetic nanoparticles (MNPs) are a new and promising addition to the spectrum of biomedicines. Their promise revolves around the broad versatility and biocompatibility of the MNPs and their unique physicochemical properties. Guided by applied external magnetic fields, MNPs represent a cutting-edge tool designed to improve diagnosis and therapy of a broad range of inflammatory, infectious, genetic and degenerative diseases. Magnetic hyperthermia, targeted drug and gene delivery, cell tracking, protein bioseparation and tissue engineering are but a few applications being developed for MNPs. MNPs toxicities linked to shape, size and surface chemistry are real and must be addressed before clinical use is realized. This article presents both the promise and perils of this new nanotechnology, with an eye towards opportunity in translational medical science. PMID:24910878

Singh, Dhirender; McMillan, JoEllyn M; Kabanov, Alexander V; Sokolsky-Papkov, Marina; Gendelman, Howard E

2014-01-01

263

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

264

Magnetic nanoparticle imaging using multiple electron paramagnetic resonance activation sequences  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles play an important role in several biomedical applications such as hyperthermia, drug targeting, and disease detection. To realize an effective working of these applications, the spatial distribution of the particles needs to be accurately known, in a non-invasive way. Electron Paramagnetic Resonance (EPR) is a promising and sensitive measurement technique for recovering these distributions. In the conventional approach, EPR is applied with a homogeneous magnetic field. In this paper, we employ different heterogeneous magnetic fields that allow to stabilize the solution of the associated inverse problem and to obtain localized spatial information. A comparison is made between the two approaches and our novel adaptation shows an average increase in reconstruction quality by 5% and is 12 times more robust towards noise. Furthermore, our approach allows to speed up the EPR measurements while still obtaining reconstructions with an improved accuracy and noise robustness compared to homogeneous EPR.

Coene, A.; Crevecoeur, G.; Dupré, L.

2015-05-01

265

Evaluation of Hyperthermia of Magnetic Nanoparticles by Dehydrating DNA  

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

266

Bench-to-bedside translation of magnetic nanoparticles.  

PubMed

Magnetic nanoparticles (MNPs) are a new and promising addition to the spectrum of biomedicines. Their promise revolves around the broad versatility and biocompatibility of the MNPs and their unique physicochemical properties. Guided by applied external magnetic fields, MNPs represent a cutting-edge tool designed to improve diagnosis and therapy of a broad range of inflammatory, infectious, genetic and degenerative diseases. Magnetic hyperthermia, targeted drug and gene delivery, cell tracking, protein bioseparation and tissue engineering are but a few applications being developed for MNPs. MNPs toxicities linked to shape, size and surface chemistry are real and must be addressed before clinical use is realized. This article presents both the promise and perils of this new nanotechnology, with an eye towards opportunity in translational medical science. PMID:24910878

Singh, Dhirender; McMillan, JoEllyn M; Kabanov, Alexander V; Sokolsky-Papkov, Marina; Gendelman, Howard E

2014-04-01

267

Preparation and optimization of chitosan nanoparticles and magnetic chitosan nanoparticles as delivery systems using Box-Behnken statistical design.  

PubMed

Chitosan nanoparticles and magnetic chitosan nanoparticles can be applied as delivery systems for the anti-Alzheimer drug tacrine. Investigation was carried out to elucidate the influence of process parameters on the mean particle size of chitosan nanoparticles produced by spontaneous emulsification. The method was optimized using design of experiments (DOE) by employing a 3-factor, 3-level Box-Behnken statistical design. This statistical design is used in order to achieve the minimum size and suitable morphology of nanoparticles. Also, magnetic chitosan nanoparticles were synthesized according to optimal method. The designed nanoparticles have average particle size from 33.64 to 74.87nm, which were determined by field emission scanning electron microscopy (FE-SEM). Drug loading in the nanoparticles as drug delivery systems has been done according to the presented optimal method and appropriate capacity of drug loading was shown by ultraviolet spectrophotometry. Chitosan and magnetic chitosan nanoparticles as drug delivery systems were characterized by Diffuse Reflectance Fourier Transform Mid Infrared spectroscopy (DR-FTMIR). PMID:23571126

Elmizadeh, Hamideh; Khanmohammadi, Mohammadreza; Ghasemi, Keyvan; Hassanzadeh, Gholamreza; Nassiri-Asl, Marjan; Garmarudi, Amir Bagheri

2013-06-01

268

Measuring and modeling the magnetic settling of superparamagnetic nanoparticle dispersions.  

PubMed

In this paper, we present settling experiments and mathematical modeling to study the magnetic separation of superparamagnetic iron-oxide nanoparticles (SPIONs) from a brine. The experiments were performed using SPIONs suspensions of concentration between 3 and 202g/L dispersed in water and separated from the liquid under the effect of a permanent magnet. A 1D model was developed in the framework of the sedimentation theory with a conservation law for SPIONs and a mass flux function based on the Newton's law for motion in a magnetic field. The model describes both the hindering effect of suspension concentration (n) during settling due to particle collisions and the increase in settling rate due to the attraction of the SPIONs towards the magnet. The flux function was derived from the settling experiments and the numerical model validated against the analytical solution and the experimental data. Suspensions of SPIONs were of 2.8cm initial height, placed on a magnet, and monitored continuously with a digital camera. Applying a magnetic field of 0.5T of polarization, the SPION's velocity was of approximately 3·10(-5)m/s close to the magnet and decreases of two orders of magnitude across the domain. The process was characterized initially by a classical sedimentation behavior, i.e., an upper interface between the clear water and the suspension slowly moving towards the magnet and a lower interface between the sediment layer and the suspension moving away from the magnet. Subsequently, a rapid separation of nanoparticle occured suggesting a non-classical settling phenomenon induced by magnetic forces which favor particle aggregation and therefore faster settling. The rate of settling decreased with n and an optimal condition for fast separation was found for an initial n of 120g/L. The model agrees well with the measurements in the early stage of the settling, but it fails to describe the upper interface movement during the later stage, probably because of particle aggregation induced by magnetization which is not accounted for in the model. PMID:25700211

Prigiobbe, Valentina; Ko, Saebom; Huh, Chun; Bryant, Steven L

2015-06-01

269

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

270

Dynamic Magnetic Fields Remote-Control Apoptosis via Nanoparticle Rotation  

PubMed Central

The ability to control the movement of nanoparticles remotely and with high precision would have far-reaching implications in many areas of nanotechnology. We have designed a unique dynamic magnetic field (DMF) generator that can induce rotational movements of superparamagnetic iron oxide nanoparticles (SPIONs). We examined whether the rotational nanoparticle movement could be used for remote induction of cell death by injuring lysosomal membrane structures. We further hypothesized that the shear forces created by the generation of oscillatory torques (incomplete rotation) of SPIONs bound to lysosomal membranes would cause membrane permeabilization, lead to extravasation of lysosomal contents into the cytoplasm, and induce apoptosis. To this end, we covalently conjugated SPIONs with antibodies targeting the lysosomal protein marker LAMP1 (LAMP1-SPION). Remote activation of slow rotation of LAMP1-SPIONs significantly improved the efficacy of cellular internalization of the nanoparticles. LAMP1-SPIONs then preferentially accumulated along the membrane in lysosomes in both rat insulinoma tumor cells and human pancreatic beta cells due to binding of LAMP1-SPIONs to endogenous LAMP1. Further activation of torques by the LAMP1-SPIONs bound to lysosomes resulted in rapid decrease in size and number of lysosomes, attributable to tearing of the lysosomal membrane by the shear force of the rotationally activated LAMP1-SPIONs. This remote activation resulted in an increased expression of early and late apoptotic markers and impaired cell growth. Our findings suggest that DMF treatment of lysosome-targeted nanoparticles offers a noninvasive tool to induce apoptosis remotely and could serve as an important platform technology for a wide range of biomedical applications. PMID:24597847

2015-01-01

271

Maximizing Hysteretic Losses in Magnetic Ferrite Nanoparticles via Model-Driven Synthesis and Materials Optimization  

E-print Network

This article develops a set of design guidelines for maximizing heat dissipation characteristics of magnetic ferrite MFe[subscript 2]O[subscript 4] (M = Mn, Fe, Co) nanoparticles in alternating magnetic fields. Using ...

Chen, Ritchie

272

Magnetic relaxation in nano-particle stacks  

NASA Astrophysics Data System (ADS)

The remanent magnetisation and magnetic relaxation of Ni-Cu/Cu superlattice nanowires have been investigated. Arrays of superlattice nanowires were prepared by template deposition through polycarbonate nanoporous membranes using a single electrolyte bath. The thicknesses of nickel-rich layers (tNi) and copper layers (tCu) were independently controlled by monitoring the current during deposition. A study of the remanent magnetisation at 5K for tNi = 30Å and a range of values of tCu reveals the existence of inter-layer demagnetising interactions within each array. However the demagnetising interaction strength appears to reach a minimum level, believed to be due to intra-layer interactions caused by island formation within nickel-rich layers. Magnetic relaxation measurements on the same arrays after removal of a saturating (5T) field at various temperatures show M to decrease linearly with ln(t). The data were analyzed using the T ln(t/?0) scaling technique, revealing the effective energy barrier distribution of the arrays to be constructed of two components, possibly due to non- (or weakly-) interacting particles and strongly-interacting particles respectively. The weakly-interacting component is observed to decrease with decreasing tCu and is believed to be caused by large individual nickel islands (corresponding to inter-layer interactions), while the strongly-interacting component is believed to be due to fragmented nickel islands (corresponding to intra-layer interactions).

Robinson, A.; Southern, P.; Schwarzacher, W.

2005-01-01

273

Hybrid nanoparticle architecture for cellular uptake and bioimaging: direct crystallization of a polymer immobilized with magnetic nanoparticles on carbon nanotubes  

NASA Astrophysics Data System (ADS)

We describe here the success of an innovative approach of direct immobilization of magnetic nanoparticles (MNPs) onto carbon nanotubes (CNTs). The approach involved functionalization of magnetic nanoparticles and consequent covalent linkage to a copolymer (PE-b-PEG). Next, the immobilized magnetic nanoparticles on the copolymer were directly crystallized on the long axis of CNTs, where the interfacial adhesion comes from electrostatic and van der Waals interaction. The intracellular trafficking of a hybrid nanoparticle system [(PE-b-PEG)-MNP-CNT-FITC] in HeLa cells was monitored using a fluorescent marker, FITC, conjugated to the nanoparticle system. The distribution of the nanoparticle system inside cells was studied by fluorescence microscopy in a time and dose dependent manner, and it was observed that the nanoparticles are located in the cytoplasm and no apparent cell death was observed at the concentration studied. Also, the effect of an externally applied magnetic field on actin cytoskeleton, cell morphology and intracellular uptake of iron was studied. The approach described here is promising for simultaneous imaging and monitoring intracellular uptake.

Depan, D.; Misra, R. D. K.

2012-09-01

274

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

275

Magnetic and Mössbauer studies of fucan-coated magnetite nanoparticles for application on antitumoral activity  

NASA Astrophysics Data System (ADS)

Fucan-coated magnetite (Fe3O4) nanoparticles were synthesized by the co-precipitation method and studied by Mössbauer spectroscopy and magnetic measurements. The sizes of the nanoparticles were 8-9 nm. Magnetization measurements and Mössbauer spectroscopy at 300 K revealed superparamagnetic behavior. The magnetic moment of the Fe3O4 is partly screened by the Fucan coating aggregation. When the magnetite nanoparticles are capped with oleic acid or fucan, reduced particle-particle interaction is observed by Mössbauer and TEM studies. The antitumoral activity of the fucan-coated nanoparticles were tested in Sarcoma 180, showing an effective reduction of the tumor size.

Silva, V. A. J.; Andrade, P. L.; Bustamante, Angel; de los Santos Valladares, L.; Mejia, M.; Souza, I. A.; Cavalcanti, K. P. S.; Silva, M. P. C.; Aguiar, J. Albino

2014-01-01

276

Synthesis of high magnetization Fe and FeCo nanoparticles by high temperature chemical reduction  

NASA Astrophysics Data System (ADS)

Fe and FeCo ferromagnetic nanoparticles in the 5-10 nm size regimes featuring high magnetization were synthesized using a modified chemical reduction method. The structure and morphology of these nanoparticles were confirmed by XRD and TEM analysis. These small, monodisperse and phase pure nanoparticles exhibited magnetic saturation of 210 emu/g (Fe) and 220 emu/g (Fe+Co) for Fe and FeCo nanoparticles respectively. The magnetization was found to be dependent on the temperature at which the reducing agent was introduced.

Kandapallil, Binil; Colborn, Robert E.; Bonitatibus, Peter J.; Johnson, Francis

2015-03-01

277

Quantum dots incorporated magnetic nanoparticles for imaging colon carcinoma cells  

PubMed Central

Background Engineered multifunctional nanoparticles (NPs) have made a tremendous impact on the biomedical sciences, with advances in imaging, sensing and bioseparation. In particular, the combination of optical and magnetic responses through a single particle system allows us to serve as novel multimodal molecular imaging contrast agents in clinical settings. Despite of essential medical imaging modalities and of significant clinical application, only few nanocomposites have been developed with dual imaging contrast. A new method for preparing quantum dots (QDs) incorporated magnetic nanoparticles (MNPs) based on layer-by-layer (LbL) self-assembly techniques have developed and used for cancer cells imaging. Methods Here, citrate - capped negatively charged Fe3O4 NPs were prepared and coated with positively - charged hexadecyltrimethyl ammonium bromide (CTAB). Then, thiol - capped negatively charged CdTe QDs were electrostatically bound with CTAB. Morphological, optical and magnetic properties of the fluorescent magnetic nanoparticles (FMNPs) were characterized. Prepared FMNPs were additionally conjugated with hCC49 antibodies fragment antigen binding (Fab) having binding affinity to sialylated sugar chain of TAG-72 region of LS174T cancer cells, which was prepared silkworm expression system, and then were used for imaging colon carcinoma cells. Results The prepared nanocomposites were magnetically responsive and fluorescent, simultaneously that are useful for efficient cellular imaging, optical sensing and magnetic separation. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) revealed that the particle size is around 50 nm in diameter with inner magnetic core and outer CdTe QDs core-shell structure. Cytotoxicity test of prepared FMNPs indicates high viability in Vero cells. NPs conjugated with anti cancer antibodies were successfully labeled on colon carcinoma cells (LS174) in vitro and showed significant specificity to target cells. Conclusion The present report demonstrates a simple synthesis of CdTe QDs-Fe3O4 NPs. The surface of the prepared FMNPs was enabled simple conjugation to monoclonal antibodies by electrostatic interaction. This property further extended their in vitro applications as cellular imaging contrast agents. Such labeling of cells with new fluorescent-magneto nanoprobes for living detection is of interest to various biomedical applications and has demonstrated the potential for future medical use. PMID:23957878

2013-01-01

278

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

279

Collective behaviour in two-dimensional cobalt nanoparticle assemblies observed by magnetic force microscopy  

Microsoft Academic Search

The use of magnetic nanoparticles in the development of ultra-high-density recording media is the subject of intense research. Much of the attention of this research is devoted to the stability of magnetic moments, often neglecting the influence of dipolar interactions. Here, we explore the magnetic microstructure of different assemblies of monodisperse cobalt single-domain nanoparticles by magnetic force microscopy and magnetometric

Pau Gorostiza; Deborah M. Aruguete; Neus G. Bastus; A. Paul Alivisatos; Victor F. Puntes

2004-01-01

280

Acid-Sensitive Magnetic Nanoparticles as Potential Drug Depots.  

PubMed

Superparamagnetic magnetic nanoparticles were successfully functionalized with poly(methacrylic acid) via atom transfer radical polymerization, followed by conjugation to doxorubicin (Dox). Because of pH-sensitive hydrazone linkages, the rate and extent of Dox release from the particles was higher at a lower pH and/or a higher temperature than at physiological conditions. Appropriate changes to the pH and temperature can increase the drug release from the particles. Because of the released drug, the particles were found to be cytotoxic to human breast cancer cells in vitro. Such magnetic nanoparticles, with the potential to retain drug under physiological conditions and release the drug in conditions where the pH is lower or temperature is higher, may be useful in magnetic drug targeting by reducing the side effects of the drug caused to healthy tissues. In addition, they may serve as hyperthermia agents where the high temperatures used in hyperthermia can trigger further drug release. PMID:21760639

Wuang, Shy Chyi; Neoh, Koon Gee; Kang, En-Tang; Leckband, Deborah E; Pack, Daniel W

2011-06-01

281

Preparation and protein immobilization of magnetic dialdehyde starch nanoparticles.  

PubMed

Superparamagnetic Fe3O4 nanoparticles were obtained using a hydrolysis product of starch, i.e., ?-d-glucose, as the reducing agent and without any additional stabilizer and dispersant by a facile and green method at mild temperature. Magnetic dialdehyde starch nanoparticles (MDASN) were successfully synthesized with dialdehyde starch (DAS) as wrapper and epichlorohydrin as cross-linker by coembedding method. Bovine serum albumin (BSA) as a model drug was immobilized on the suface of MDASN. The particle size distribution of MDASN was 50-150 nm, and the average size was about 100 nm. The content of aldehyde group in DAS was 59.5%, and the package rate of DAS in MDASN was 33.2%. The loading amount and encapsulation efficiency of MDASN loading BSA were 5.0% and 54.4%, respectively. The saturation magnetization of MDASN at 300 K was 29.5 emu/g without coercivity and remanence. The as-prepared MDASN have not only lots of aldehyde functional groups but also stronger magnetic response, which might have potential applications such as drug carriers and targeted drug release. PMID:23528154

Lu, Wensheng; Shen, Yuhua; Xie, Anjian; Zhang, Weiqiang

2013-04-11

282

Synthesis of magnetic multicomponent nanoparticles CuxNi1-xFe2O4  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles (MNPs) are of great importance in many biomedical applications, such as drug delivery, hyperthermia, and magnetic resonance imaging (MRI) contrast enhancement. To build the most effective magnetic nanoparticle systems for various biomedical applications, characteristics of particle, including size, surface chemistry, magnetic properties, and toxicity have to be fully investigated. In this work, the effects of some production methods of the magnetic nanoparticles for the bio-medical applications are discussed. In this study, multicomponents of CuxNi1-xFe2O4 nanoparticles (where x=0, 0.6, and 1) were prepared by the hydrothermal synthesis method. In addition, X-ray powder diffractometry (XRD), scanning electron microscopy (SEM), and a vibrating scanning magnetometer (VSM) were used to characterize the structural, morphological and magnetic properties of the nanoparticles. The particle sizes of the samples were measured by Malvern Instruments Zeta Sizer Nano-ZS instrument. The data were recorded under magnetic fields for different ratios of CuxNi1-xFe2O4 nanoparticles. The temperature dependence of field cooled (FC) magnetization of the CuxNi1-xFe2O4 samples has been shown in this work. Magnetizations change with decreasing the dopant value of Cu. The magnetic phase transition was observed for CuxNi1-xFe2O4 nanoparticles.

Bingölbali, A.; Do?an, N.; Ye?il, Z.; Asiltürk, M.

2015-01-01

283

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

284

Photosensitizer-conjugated magnetic nanoparticles for in vivo simultaneous magnetofluorescent imaging and targeting therapy  

Microsoft Academic Search

A major challenge in nanotechnology and nanomedicine is to integrate tumor targeting, imaging, and selective therapy functions into a small single nanoparticle (<50 nm). Herein, photosensitizer-conjugated magnetic nanoparticles with ?20 nm in diameter were strategically designed and prepared for gastric cancer imaging and therapy. The second generation photosensitizer chlorin e6 (Ce6) was covalently anchored on the surface of magnetic nanoparticles with silane

Peng Huang; Zhiming Li; Jing Lin; Dapeng Yang; Guo Gao; Cheng Xu; Le Bao; Chunlei Zhang; Kan Wang; Hua Song; Hengyao Hu; Daxiang Cui

2011-01-01

285

Magnetic resonance of polyaspartic acid-coated magnetite nanoparticles administered in mice  

Microsoft Academic Search

Molecular-coated magnetic nanoparticles (MNPs) have attracted a lot of attention, not only because of their unusual properties but also due to their potential biomedical applications. Preliminary genetic and toxicity tests with a magnetic fluid (MF) sample based on magnetite nanoparticles surface-coated with polyaspartic acid (PAMF) showed reasonable biocompatibility. Nevertheless, biodistribution aspects of PAMF sample were not investigated yet. In the

N. Sadeghiani; L. S. Barbosa; M. H. A. Guedes; S. B. Chaves; J. G. Santos; O. Silva; F. Pelegrini; R. B. Azevedo; P. C. Morais; Z. G. M. Lacava

2005-01-01

286

Selective reduction of the interaction of magnetic nanoparticles with leukocytes and tumor cells by human plasma  

NASA Astrophysics Data System (ADS)

Carboxymethyl-dextran coated magnetic nanoparticles can interact with viable human cells. The interaction of the nanoparticles is cell-type specific. The addition of human plasma led to a dramatic reduction of magnetically separable leukocytes in comparison to tumor cells. We conclude that low plasma concentrations might support an efficient enrichment of circulating epithelial cells from the peripheral blood of tumor patients.

Schwalbe, Manuela; Jörke, Cornelia; Buske, Norbert; Höffken, Klaus; Pachmann, Katharina; Clement, Joachim H.

2005-05-01

287

In vivo animal experimental research of magnetic nanoparticles influence on pulse wave  

Microsoft Academic Search

In vivo animal experimental research is performed to study the influence of magnetic nanoparticles on the pulse wave. An interventional pulse wave transducer is connected to the rabbit's blood circulation through the ingenious two-end carotid intubations, so that the pulse wave with low noise could be acquired. The data obtained before and after the injection of the magnetic nanoparticles, which

Yupeng Yao; Shouliang Qi; Jingshu Zhang; Bo Song; Cong Feng; Lisheng Xu

2010-01-01

288

Preparation, Structure, and Properties of Magnetic Materials Based on Co-Containing Nanoparticles  

Microsoft Academic Search

The recent experimental data on the preparation and properties of materials containing Co-based magnetic nanoparticles are summarized. Particular attention is focused on the synthesis of cobalt nanoparticles in “rigid” matrices (polymers, metals, and solid surfaces) and their static magnetic properties, which are of great importance for practical applications. The conclusion is made that surface effects play an important role in

S. P. Gubin; Yu. A. Koksharov

2002-01-01

289

On-chip manipulation of single magnetic nano-particles via domain walls conduits  

Microsoft Academic Search

We demonstrate on-chip manipulation of individual nanoparticles in suspension with active control of position at the nanometer scale, through the control of the motion of geometrically constrained domain walls (DWs) in magnetic nano-conduits. Magnetic nanoparticles are captured by the stray field of a DW and their transport and release is obtained via precise control over DW nucleation, displacement, and annihilation

R. Bertacco; M. Donolato; M. Gobbi; M. Cantoni; D. Petti; S. Brivio; V. Metlushko; B. Ilic; P. Vavassori

2009-01-01

290

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.

291

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

292

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

PubMed

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. PMID:24730845

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

2014-03-01

293

Elucidating the Function of Penetratin and a Static Magnetic Field in Cellular Uptake of Magnetic Nanoparticles  

PubMed Central

Nanotechnology plays an increasingly important role in the biomedical arena. In particular, magnetic nanoparticles (mNPs) have become important tools in molecular diagnostics, in vivo imaging and improved treatment of disease, with the ultimate aim of producing a more theranostic approach. Due to their small sizes, the nanoparticles can cross most of the biological barriers such as the blood vessels and the blood brain barrier, thus providing ubiquitous access to most tissues. In all biomedical applications maximum nanoparticle uptake into cells is required. Two promising methods employed to this end include functionalization of mNPs with cell-penetrating peptides to promote efficient translocation of cargo into the cell and the use of external magnetic fields for enhanced delivery. This study aimed to compare the effect of both penetratin and a static magnetic field with regards to the cellular uptake of 200 nm magnetic NPs and determine the route of uptake by both methods. Results demonstrated that both techniques increased particle uptake, with penetratin proving more cell specific. Clathrin- medicated endocytosis appeared to be responsible for uptake as shown via PCR and western blot, with Pitstop 2 (known to selectively block clathrin formation) blocking particle uptake. Interestingly, it was further shown that a magnetic field was able to reverse or overcome the blocking, suggesting an alternative route of uptake. PMID:24275948

Chaudhary, Suman; Smith, Carol Anne; del Pino, Pablo; de la Fuente, Jesus M.; Mullin, Margaret; Hursthouse, Andrew; Stirling, David; Berry, Catherine C.

2013-01-01

294

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

295

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

Microsoft Academic Search

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

Alexander L. Kovarski; Olga N. Sorokina

2007-01-01

296

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

297

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

298

Magnetic nanoparticles: preparation, physical properties, and applications in biomedicine  

PubMed Central

Finally, we have addressed some relevant findings on the importance of having well-defined synthetic strategies developed for the generation of MNPs, with a focus on particle formation mechanism and recent modifications made on the preparation of monodisperse samples of relatively large quantities not only with similar physical features, but also with similar crystallochemical characteristics. Then, different methodologies for the functionalization of the prepared MNPs together with the characterization techniques are explained. Theorical views on the magnetism of nanoparticles are considered. PMID:22348683

2012-01-01

299

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

300

Magnetic capture of a single magnetic nanoparticle using nanoelectromagnets  

E-print Network

are extracted from magnetotactic bacteria and their diameter is approximately 50 nm. We show that a single, and magnetotactic bacteria,6­9 but the manipulation of individual magnetic ma- terials in a nanometer scale has around the electromagnet and is useful to find out the capture mechanism. II. EXPERIMENTS A magnetotactic

Hwang, Sung Woo

301

Modeling of the transitions between magnetic states of core/shell nanoparticles  

NASA Astrophysics Data System (ADS)

Core/shell nanoparticles can be used in industry, medicine and biophysics, due to their unique properties. Theoretical studies of core/shell nanoparticles are mainly based on the Stoner-Wohlfarth model, and the Monte-Carlo simulation is mostly used the Metropolis algorithm. This method is an extension of one-phase nanoparticle model and not entirely correct for solving the magnetic states of core/shell nanoparticles, which represents a magnetic core covered with a magnetic or nonmagnetic shell. We developed a model of core/shell nanoparticles based on the analysis of total energy consisting of anisotropy energy Ea, magnetostatic interaction energy Em, exchange interaction energy Eex and energy of magnetic moment of the grain in external magnetic field Eh: E=Ea+Em+Eex+EH.

Iliushin, I. G.; Afremov, L. L.; Anisimov, S. V.

2015-01-01

302

Hydrogel-magnetic nanoparticles with immobilized L-asparaginase for biomedical applications.  

PubMed

The association of magnetic nanoparticles, which could be controlled by a magnetic field and have dimensions which facilitate their penetration in cells/tissues, with hydrogel type biopolymeric shells confer them compatibility and the capacity to retain and deliver bioactive substances. The main objective of this work is the development of a new system based on a biocompatible polymer with organic-inorganic structure capable of vectoring support for biologic active agents (L: -asparaginase, e.g.). Characterization of size and morphology of the hydrogel-magnetic nanoparticles with entrapped L: -asparaginase was made using Dynamic Light Scattering method, Transmission Electron Microscopy and Confocal Microscopy. The structure of magnetic nanoparticles coated with hydrogel was characterized by Fourier Transformed Infrared Spectroscopy. The cytotoxicity of nanoparticles was evaluated and also the interactions with microorganisms. We obtained hydrogel-magnetic nanoparticles with L: -asparaginase entrapped, with sizes below 30 nm in dried stage, capable to penetrate the cells and tissues. PMID:19160022

Teodor, Eugenia; Litescu, Simona-Carmen; Lazar, Veronica; Somoghi, Raluca

2009-06-01

303

Self-assembly of magnetic nanoparticles in evaporating solution.  

PubMed

When deposited from an evaporating solution onto a substrate, even nondescript nanoparticles can organize into intricate spatial patterns. Here we show that a simple but long-ranged anisotropy in nanoparticles' interactions can greatly enrich this scenario. In experiments with colloidal Co nanocrystals, which bear a substantial magnetic dipole, we observe assemblies quite distinct from those formed by nonmagnetic particles. Reflecting the strongly nonequilibrium nature of this process, nanocrystal aggregates also differ substantially from expected low-energy arrangements. Using coarse-grained computer simulations of dipolar nanoparticles, we have identified several dynamical mechanisms from which such unusual morphologies can arise. For particles with modest dipole moments, transient connections between growing domains frustrate phase separation into sparse and dense regions on the substrate. Characteristic length scales of the resulting cellular networks depend non-monotonically on the depth of quenches we use to mimic the effects of solvent evaporation. For particles with strong dipole moments, chain-like aggregates formed at early times serve as the agents of assembly at larger scales. Their effective interactions drive the formation of layered loop structures similar to those observed in experiments. PMID:21158454

Ku, JiYeon; Aruguete, Deborah M; Alivisatos, A Paul; Geissler, Phillip L

2011-02-01

304

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

305

Spectroscopic characterization of magnetic Fe3O4@Au core shell nanoparticles.  

PubMed

The magnetic nanoparticles iron oxide (Fe3O4) nanoparticles and iron oxide/gold core-shell (Fe3O4/Au) nanoparticles were synthesized and their catalytic photo-degradation activity towards malathion as example of organophosphorus pesticides were reported. Iron oxide (Fe3O4) magnetic nanoparticle was successfully prepared through co-precipitation method by the reduction of ferric chloride (FeCl3) using ascorbic acid. The morphology of the prepared nanoparticles was characterized by the TEM and XRD (X-ray diffraction) techniques. Degradation of 10 ppm of malathion in the presence of these nanoparticles under UV radiation was monitored using (HPLC) and UV-visible spectra. Fe3O4/Au nanoparticles showed higher efficiency in photo-degradation of malathion than Fe3O4 ones. PMID:25617979

Fouad, Dina M; El-Said, Waleed A; Mohamed, Mona B

2015-04-01

306

Potential of magnetic nanoparticles for targeted drug delivery  

PubMed Central

Nanoparticles (NPs) play an important role in the molecular diagnosis, treatment, and monitoring of therapeutic outcomes in various diseases. Their nanoscale size, large surface area, unique capabilities, and negligible side effects make NPs highly effective for biomedical applications such as cancer therapy, thrombolysis, and molecular imaging. In particular, nontoxic superparamagnetic magnetic NPs (MNPs) with functionalized surface coatings can conjugate chemotherapeutic drugs or be used to target ligands/proteins, making them useful for drug delivery, targeted therapy, magnetic resonance imaging, transfection, and cell/protein/DNA separation. To optimize the therapeutic efficacy of MNPs for a specific application, three issues must be addressed. First, the efficacy of magnetic targeting/guidance is dependent on particle magnetization, which can be controlled by adjusting the reaction conditions during synthesis. Second, the tendency of MNPs to aggregate limits their therapeutic use in vivo; surface modifications to produce high positive or negative charges can reduce this tendency. Finally, the surface of MNPs can be coated with drugs which can be rapidly released after injection, resulting in targeting of low doses of the drug. Drugs therefore need to be conjugated to MNPs such that their release is delayed and their thermal stability enhanced. This chapter describes the creation of nanocarriers with a high drug-loading capacity comprised of a high-magnetization MNP core and a shell of aqueous, stable, conducting polyaniline derivatives and their applications in cancer therapy. It further summarizes some newly developed methods to synthesize and modify the surfaces of MNPs and their biomedical applications. PMID:24198498

Yang, Hung-Wei; Hua, Mu-Yi; Liu, Hao-Li; Huang, Chiung-Yin; Wei, Kuo-Chen

2012-01-01

307

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

308

Preparation and magnetic properties of spindle porous iron nanoparticles  

SciTech Connect

Spindle porous iron nanoparticles were firstly synthesized by reducing the pre-synthesized hematite ({alpha}-Fe{sub 2}O{sub 3}) spindle particles with hydrogen gas. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption/desorption isotherms and vibrating sample magnetometry (VSM). A lattice shrinkage mechanism was employed to explain the formation process of the porous structure, and the adsorbed phosphate was proposed as a protective shell in the reduction process. N{sub 2} adsorption/desorption result showed a Brunauer-Emmett-Teller (BET) surface area of 29.7 m{sup 2}/g and a continuous pore size distribution from 2 nm to 100 nm. The magnetic hysteresis loop of the synthesized iron particles showed a saturation magnetization of 84.65 emu/g and a coercivity of 442.36 Oe at room temperature.

Lv Baoliang [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Number 27, Tao Yuan South Road, Taiyuan, Shanxi 030001 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100039 (China); Xu Yao [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Number 27, Tao Yuan South Road, Taiyuan, Shanxi 030001 (China)], E-mail: xuyao@sxicc.ac.cn; Wu Dong; Sun Yuhan [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Number 27, Tao Yuan South Road, Taiyuan, Shanxi 030001 (China)

2009-05-06

309

Characterization of Magnetic NiFe Nanoparticles with Controlled Bimetallic Composition  

SciTech Connect

The exploration of the magnetic properties of bimetallic alloy nanoparticles for various technological applications requires the ability to control the morphology, composition, and surface properties. In this report, we describe new findings of an investigation of the morphology and composition of NiFe alloy nanoparticles synthesized under controlled conditions. The controllability over the bimetallic composition has been demonstrated by the observation of an approximate linear relationship between the composition in the nanoparticles and in the synthetic feeding. The morphology of the NiFe nanoparticles is consistent with an fcc-type alloy, with the lattice strain increasing linearly with the iron content in the nanoparticles. The alloy nanoparticles exhibit remarkable resistance to air oxidation in comparison with Ni or Fe particles. The thermal stability and the magnetic properties of the as-synthesized alloy nanoparticles are shown to depend on the composition. The alloy nanoparticles have also be sown to display low saturation magnetization and coercivity values in comparison with the Ni nanoparticles, in line with the superparamagnetic characteristic. These findings have important implications for the design of stable and controllable magnetic nanoparticles for various technological applications.

Liu, Yan; Chi, Yanxiu; Shan, Shiyao; Yin, Jun; Luo, Jin; Zhong, Chuan-Jian

2014-02-25

310

Structural and magnetic properties of polymer coated iron based nanoparticles for biomedical applications  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles have recently attracted much attention for potential biomedical applications such as targeted drug delivery, magnetic resonance imaging contrast agents and hyperthermia treatment of cancerous cells. Future research on biomedical applications also includes use of magnetic nanoparticles for cell and DNA separation. By functionalizing magnetic nanoparticles with cells or DNA selective biomolecules, the particles attach to the target and are removed from the sample upon passing through magnetic field gradients. The field gradients apply a force that attracts the particles given by the equation F = ?(m · B), where m is the magnetization of the MNP, and B is the applied magnetic field. This type of magnetic manipulation is potential for in vivo applications such as targeted drug delivery, magnetic resonance imaging contrast enhancement and hyperthermia treatment of cancer. The magnitude of the field gradients of magnetic nanoparticles are significantly reduced due to the inverse square law dependence of magnetic field strength and subsequently the forces set up are reduced. Although the research in this field has focused primarily on iron oxide nanoparticles, these oxide nanoparticles have a low magnetization that renders them ineffective, at the distances required for in vivo applications, due to the reduced forces felt by the nanoparticles. Successful implementation of such magnetic nanoparticles based system in vivo may require higher magnetization. The aim of this proposal is to synthesize high magnetization Fe-based MNPs functionalized with artificial proteins. The research described in this dissertation focuses on synthesis, size control, structural and magnetic characterization and associated experimental studies to characterize their properties for application in magnetic fluid hyperthermia and magnetic resonance imaging applications. The method used for the synthesis of the Fe-based nanoparticles is the conventional borohydride reduction of the metal salt solution. Since our intention is to synthesize iron based nanoparticles we used iron salts such as FeCl3. A polymer such as polyethylene glycol is coated onto the oxide shell to make it biocompatible. Parameters such as length of the tube, diameter of the Y-tube junction and concentration of the reactants were varied to study the effect on particle size, structure and morphology of the magnetic nanoparticles. X-ray diffraction measurements revealed that the particles typically contain three iron based phases such as a crystalline (alpha-Fe), nanocrystalline/amorphous (a-FeB/n-Fe) and Fe-oxide. By controlling the synthesis parameters such as length of the reaction tube, inner diameter of the Y-tube and concentration of the reagents the volume percentage of the three phases of the nanoparticles, viz. crystalline phase, amorphous phase and Fe-Oxide phases can be controlled effectively. The Fe-Oxide phase could not be determined whether is magnetite and maghemite phase because of the very broad nature of the peak. Transmission electron microscopy was used to study the particle size and the microstructural property of the samples. Samples with particle size in the range of 3 nm to 30 nm were fabricated. The magnetic properties of the nanoparticles studied were measured with a vibrating sample magnetometer with a maximum field of 1 Tesla. The particles magnetic properties such as magnetization and coercivity were typical of a soft ferromagnetic material with a high magnetization (in emu/g) and the coercivity was in range of 50 to 450 Oe. The nanoparticles synthesized were used to study their performance in magnetic fluid hyperthermia and magnetic resonance imaging applications. In the hyperthermia, the power loss due to an alternating magnetic field had a direct correlation with the magnetization and the particle size of the nanoparticle. The power loss in magnetic fluid hyperthermia is an outcome from four loss mechanism, they are Brownian rotational loss, Neel's relaxational loss, hysteresis loss and eddy current loss. The Brownian rotation loss

Balakrishnan, Srinivasan

311

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

312

Magnetic field calculations for iron oxide nanoparticles for MRI  

NASA Astrophysics Data System (ADS)

The susceptibility effects of superparamagnetic iron oxide nanoparticles (SPIONs) functionalized with triethylenglycol (TREG) and Polyethylen Glycol (PEG) has been studied, those nanoparticles have the necessary properties to be used in the clinic as contrast media in imaging by MRI[1-3]. We are considering the behavior of the magnetic field as plane wave to explain the electrical and magnetic field produced by SPIONs. Images were acquired on a 1.5T imager Philips, using mFFE Sequence. Three glass capillary tubes with a) TREG (10nm) concentration of 300 ?g/ml, and PEGCOOH 6000(10nm) with 300 ?g/ml, and 2% agarosa. Magnetic field simulations were calculated in Matlab. The plane wave that comes in contact with a sphere of radius a, an propagation constant k1, and it is in an homogeneous space k2. We consider that the electric field is linearly polarized on x-direction, with a propagation on z-positive-axis. The secondary induced field can be explained from the interior of the sphere and valid exterior points. The referred waves are transmitted and reflected, this is valid only when the wavelength is smaller than the radius of the sphere. The obtained vibrational mode is an answer of the electrical oscillation and this is projection of the disturbed magnetic field. TREG-SPIONs produce more serious susceptibility artefacts compared to PEG-SPIONs. This study is promissory due to the concordance of the results of the simulations and the inhomogeneities showed in the MR images.

Hernandez, Ricardo; Mendez Rojas, Miguel; Dies Suarez, Pilar; Hidalgo Tobón, Silvia

2014-11-01

313

Rapid immunoenzyme assay of aflatoxin B1 using magnetic nanoparticles.  

PubMed

The main limitations of microplate-based enzyme immunoassays are the prolonged incubations necessary to facilitate heterogeneous interactions, the complex matrix and poorly soluble antigens, and the significant sample dilutions often required because of the presence of organic extractants. This study presents the use of antibody immobilization on the surface of magnetic particles to overcome these limitations in the detection of the mycotoxin, aflatoxin B1. Features of the proposed system are a high degree of nanoparticle dispersion and methodologically simple immobilization of the antibodies by adsorption. Reactions between the immobilized antibodies with native and labeled antigens are conducted in solution, thereby reducing the interaction period to 5 min without impairing the analytical outcome. Adsorption of immunoglobulins on the surface of magnetic nanoparticles increases their stability in aqueous-organic media, thus minimizing the degree of sample dilution required. Testing barley and maize extracts demonstrated a limit of aflatoxin B1 detection equal to 20 pg/mL and total assay duration of 20 min. Using this method, only the 3-fold dilution of the initial methanol/water (60/40) extraction mixture in the microplate wells is necessary. The proposed pseudo-homogeneous approach could be applied toward immunodetection of a wide range of compounds. PMID:25412219

Urusov, Alexandr E; Petrakova, Alina V; Vozniak, Maxim V; Zherdev, Anatoly V; Dzantiev, Boris B

2014-01-01

314

Rapid Immunoenzyme Assay of Aflatoxin B1 Using Magnetic Nanoparticles  

PubMed Central

The main limitations of microplate-based enzyme immunoassays are the prolonged incubations necessary to facilitate heterogeneous interactions, the complex matrix and poorly soluble antigens, and the significant sample dilutions often required because of the presence of organic extractants. This study presents the use of antibody immobilization on the surface of magnetic particles to overcome these limitations in the detection of the mycotoxin, aflatoxin B1. Features of the proposed system are a high degree of nanoparticle dispersion and methodologically simple immobilization of the antibodies by adsorption. Reactions between the immobilized antibodies with native and labeled antigens are conducted in solution, thereby reducing the interaction period to 5 min without impairing the analytical outcome. Adsorption of immunoglobulins on the surface of magnetic nanoparticles increases their stability in aqueous-organic media, thus minimizing the degree of sample dilution required. Testing barley and maize extracts demonstrated a limit of aflatoxin B1 detection equal to 20 pg/mL and total assay duration of 20 min. Using this method, only the 3-fold dilution of the initial methanol/water (60/40) extraction mixture in the microplate wells is necessary. The proposed pseudo-homogeneous approach could be applied toward immunodetection of a wide range of compounds. PMID:25412219

Urusov, Alexandr E.; Petrakova, Alina V.; Vozniak, Maxim V.; Zherdev, Anatoly V.; Dzantiev, Boris B.

2014-01-01

315

Phosphonate-anchored monolayers for antibody binding to magnetic nanoparticles.  

PubMed

Targeted delivery of magnetic iron oxide nanoparticles (IONPs) to a specific tissue can be achieved by conjugation with particular biological ligands on an appropriately functionalized IONP surface. To take best advantage of the unique magnetic properties of IONPs and to maximize their blood half-life, thin, strongly bonded, functionalized coatings are required. The work reported herein demonstrates the successful application of phosphonate-anchored self-assembled monolayers (SAMs) as ultrathin coatings for such particles. It also describes a new chemical approach to the anchoring of antibodies on the surface of SAM-coated IONPs (using nucleophilic aromatic substitution). This anchoring strategy results in stable, nonhydrolyzable, covalent attachment and allows the reactivity of the particles toward antibody binding to be activated in situ, such that prior to the activation the modified surface is stable for long-term storage. While the SAMs do not have the well-packed crystallinity of other such monolayers, their structure was studied using smooth model substrates based on an iron oxide layer on a double-side polished silicon wafer. In this way, atomic force microscopy, ellipsometry, and contact angle goniometry (tools that could not be applied to the nanoparticles' surfaces) could contribute to the determination of their monomolecular thickness and uniformity. Finally, the successful conjugation of IgG antibodies to the SAM-coated IONPs such that the antibodies retain their biological activity is verified by their complexation to a secondary fluorescent antibody. PMID:21863873

Benbenishty-Shamir, Helly; Gilert, Roni; Gotman, Irena; Gutmanas, Elazar Y; Sukenik, Chaim N

2011-10-01

316

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

317

Synthesis and magnetic properties of gold coated iron oxide nanoparticles  

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

318

Study of magnetic nanoparticles and overcoatings for biological applications including a sensor device  

NASA Astrophysics Data System (ADS)

I. A general introduction to the field of nanomaterials is presented, highlighting their special attributes and characteristics. Nanoparticles in general are discussed with respect to their structure, form and properties. Magnetic particles in particular are highlighted, especially the iron oxides. The importance and interest of integrating these materials with biological media is discussed, with emphasis on transferring particles from one medium to another, and subsequent modification of surfaces with different types of materials. II. A general route to making magnetic iron oxide nanoparticles is explained, both as maghemite and magnetite, including properties of the particles and characterization. A novel method of producing magnetite particles without a ligand is then presented, with subsequent characterization and properties described. III. Attempts to coat iron oxide nanoparticles with a view to creating biofunctional magnetic nanoparticles are presented, using a gold overcoating method. Methods of synthesis and characterization are examined, with unique problems to core-shell structures analyzed. IV. Solubility of nanoparticles in both aqueous and organic media is discussed and examined. The subsequent functionalization of the surface of maghemite and magnetite nanoparticles with a variety of biomaterials including block copolypeptides, phospholipids and carboxydextran is then presented. These methods are integral to the use of magnetic nanoparticles in biological applications, and therefore their properties are examined once tailored with these molecules. V. A new type of magnetic nanoparticle sensor-type device is described. This device integrates bio-and DNA-functionalized nanoparticles with conjugate functionalized silicon dioxide surfaces. These techniques to pattern particles to a surface are then incorporated into a device with a magnetic tunnel junction, which measures magnetoresistance in the presence of an external magnetic field. This configuration thereby introduces a new way to detect magnetic nanoparticles via their magnetic properties after conjugation via biological entities.

Grancharov, Stephanie G.

319

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

320

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, Sören; Kaiser, Ute; Han, Luyang; Wiedwald, Ulf; Ziemann, Paul

2011-01-01

321

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

322

Frequency-Dependent Magnetic Susceptibility of Magnetite and Cobalt Ferrite Nanoparticles Embedded in PAA Hydrogel.  

PubMed

Chemically responsive hydrogels with embedded magnetic nanoparticles are of interest for biosensors that magnetically detect chemical changes. A crucial point is the irreversible linkage of nanoparticles to the hydrogel network, preventing loss of nanoparticles upon repeated swelling and shrinking of the gel. Here, acrylic acid monomers are adsorbed onto ferrite nanoparticles, which subsequently participate in polymerization during synthesis of poly(acrylic acid)-based hydrogels (PAA). To demonstrate the fixation of the nanoparticles to the polymer, our original approach is to measure low-field AC magnetic susceptibility spectra in the 0.1 Hz to 1 MHz range. In the hydrogel, the magnetization dynamics of small iron oxide nanoparticles are comparable to those of the particles dispersed in a liquid, due to fast Néel relaxation inside the particles; this renders the ferrogel useful for chemical sensing at frequencies of several kHz. However, ferrogels holding thermally blocked iron oxide or cobalt ferrite nanoparticles show significant decrease of the magnetic susceptibility resulting from a frozen magnetic structure. This confirms that the nanoparticles are unable to rotate thermally inside the hydrogel, in agreement with their irreversible fixation to the polymer network. PMID:23673482

van Berkum, Susanne; Dee, Joris T; Philipse, Albert P; Erné, Ben H

2013-01-01

323

Frequency-Dependent Magnetic Susceptibility of Magnetite and Cobalt Ferrite Nanoparticles Embedded in PAA Hydrogel  

PubMed Central

Chemically responsive hydrogels with embedded magnetic nanoparticles are of interest for biosensors that magnetically detect chemical changes. A crucial point is the irreversible linkage of nanoparticles to the hydrogel network, preventing loss of nanoparticles upon repeated swelling and shrinking of the gel. Here, acrylic acid monomers are adsorbed onto ferrite nanoparticles, which subsequently participate in polymerization during synthesis of poly(acrylic acid)-based hydrogels (PAA). To demonstrate the fixation of the nanoparticles to the polymer, our original approach is to measure low-field AC magnetic susceptibility spectra in the 0.1 Hz to 1 MHz range. In the hydrogel, the magnetization dynamics of small iron oxide nanoparticles are comparable to those of the particles dispersed in a liquid, due to fast Néel relaxation inside the particles; this renders the ferrogel useful for chemical sensing at frequencies of several kHz. However, ferrogels holding thermally blocked iron oxide or cobalt ferrite nanoparticles show significant decrease of the magnetic susceptibility resulting from a frozen magnetic structure. This confirms that the nanoparticles are unable to rotate thermally inside the hydrogel, in agreement with their irreversible fixation to the polymer network. PMID:23673482

van Berkum, Susanne; Dee, Joris T.; Philipse, Albert P.; Erné, Ben H.

2013-01-01

324

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

325

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

326

Folate-conjugated luminescent Fe3O4 nanoparticles for magnetic hyperthermia  

NASA Astrophysics Data System (ADS)

We demonstrate a facile approach for the synthesis of folate-conjugated luminescent iron oxide nanoparticles (FLIONs). XRD and TEM analyses reveal the formation of highly crystalline single-phase Fe3O4 nanoparticles of size about 10 nm. The conjugation of folate receptor (folic acid, FA) and luminescent molecule (fluorescein isothiocyanate, FITC) onto the surface of nanoparticles was evident from FTIR and UV-visible spectroscopy. These FLIONs show good colloidal stability, high magnetic field responsivity and excellent self-heating efficacy. Specifically, a new class of magnetic nanoparticles has been fabricated, which can be used as an effective heating source for hyperthermia.

Barick, K. C.; Rana, Suman; Hassan, P. A.

2014-04-01

327

Biofunctional magnetic ‘core–shell’ nanoparticles generated by laser ablation of iron in liquid  

NASA Astrophysics Data System (ADS)

Biofunctional ‘core–shell’ nanoparticles were generated via pulsed laser ablation of a bulk iron target in liquid containing a stabilizer agent. This novel technique for generation of magnetic nanoparticles is a prospect for potential applications in laser diagnostics and treatment of damaged cartilage. We studied the absorption spectra, magnetic properties of magnetite nanoparticles and their colloidal solutions to be used for impregnation into cartilage. Core–shell magnetite nanoparticles of 10–15?nm size have stable size distribution, low velocity of sedimentation and do not agglomerate during more than three?months of storage time.

Omelchenko, A. I.; Sobol, E. N.; Simakin, A. V.; Serkov, A. A.; Sukhov, I. A.; Shafeev, G. A.

2015-02-01

328

Adsorption of environmental pollutants using magnetic hybrid nanoparticles modified with ?-cyclodextrin  

NASA Astrophysics Data System (ADS)

Graft through strategy was utilized to coat magnetic Fe3O4 nanoparticles with poly(glycidyl methacrylate) using ordinary radical polymerization and then ?-cyclodextrin was linked onto the surface of nanoparticles. With these nanoparticles modified with cyclodextrin groups, adsorption of two model environmental pollutants, bisphenol A and copper ions, was studied. Host-guest interactions between cyclodextrin and aromatic molecules had a great contribution to the adsorption of bisphenol A, while multiple hydroxyls of cyclodextrin also helped the adsorption of copper ions. These magnetic nanoparticles could be applied in the elimination, enrichment and detection of some environmental pollutants.

Wang, Niejun; Zhou, Lilin; Guo, Jun; Ye, Qiquan; Lin, Jin-Ming; Yuan, Jinying

2014-06-01

329

Influence of surface segregation on magnetic properties of FePt nanoparticles  

SciTech Connect

Surface segregation leads to chemical disordering in magnetic alloy nanostructures and thus could have profound impact upon the magnetic properties of these nanostructures. In this study, we used the first-principles density functional theory calculation method to determine how Pt surface segregation (exchanging interior Pt with surface Fe atoms) would affect the magnetic properties of L1{sub 0} ordered FePt nanoparticles. For both cuboid and cuboctahedral FePt nanoparticles, we predicted that the Pt surface segregation process could cause a decrease in total magnetic moments, a change in (easy and/or hard) magnetization axes, and a reduction in magnetic anisotropy.

Lv, Hongyan [Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15261 (United States) [Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15261 (United States); Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Lei, Yinkai; Datta, Aditi; Wang, Guofeng [Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15261 (United States)] [Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15261 (United States)

2013-09-23

330

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

331

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

332

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

Microsoft Academic Search

Purpose  Polyethylene glycol (PEG) functionalized magnetic nanoparticles (MNPs) were tested as a drug carrier system, as a magnetic\\u000a resonance imaging (MRI) agent, and for their ability to conjugate to an antibody.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  An iron oxide core coated with oleic acid (OA) and then with OA-PEG forms a water-dispersible MNP formulation. Hydrophobic\\u000a doxorubicin partitions into the OA layer for sustained drug delivery. The

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

2010-01-01

333

Photosensitizer-conjugated magnetic nanoparticles for in vivo simultaneous magnetofluorescent imaging and targeting therapy.  

PubMed

A major challenge in nanotechnology and nanomedicine is to integrate tumor targeting, imaging, and selective therapy functions into a small single nanoparticle (<50 nm). Herein, photosensitizer-conjugated magnetic nanoparticles with ?20 nm in diameter were strategically designed and prepared for gastric cancer imaging and therapy. The second generation photosensitizer chlorin e6 (Ce6) was covalently anchored on the surface of magnetic nanoparticles with silane coupling agent. We found that the covalently incorporated Ce6 molecules retained their spectroscopic and functional properties for near-infrared (NIR) fluorescence imaging and photodynamic therapy (PDT), and the core magnetic nanoparticles offered the functions of magnetically guided drug delivery and magnetic resonance imaging (MRI). The as-prepared single particle platform is suitable for simultaneous targeting PDT and in vivo dual-mode NIR fluorescence imaging and MRI of nude mice loaded with gastric cancer or other tumors. PMID:21303717

Huang, Peng; Li, Zhiming; Lin, Jing; Yang, Dapeng; Gao, Guo; Xu, Cheng; Bao, Le; Zhang, Chunlei; Wang, Kan; Song, Hua; Hu, Hengyao; Cui, Daxiang

2011-05-01

334

Preparation of magnetic fluorochromate hybrid nanomaterials with triphenylphosphine surface modified iron oxide nanoparticles and their characterization  

NASA Astrophysics Data System (ADS)

In this study, a new magnetic hybrid nanomaterial Fe3O4@SiO2@PPh3@[CrO3F]- is instituted. Firstly, magnetic Fe3O4 nanoparticles have been synthesized by hydrothermal method. Next, the produced magnetic nanoparticles were covered with a silica shell via modified Stöber method. Then, the core-shell magnetic nanoparticles system Fe3O4@SiO2 functionalization was combined by utilizing (3-chloropropyl)trimethoxysilane and triphenylphosphine, to give the cationic part for immobilization of the anionic part of the Cr(VI) catalysts including [CrO3F]-. The structure of the catalyst after immobilization was investigated by using elemental analysis, X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and solid state UV-vis. The particle size and morphology were identified by scanning electron microscope (SEM) and XRD. Magnetization properties of nanoparticles were confirmed by vibrating sample magnetometer (VSM).

Rahimi, Rahmatollah; Maleki, Ali; Maleki, Saied

2014-04-01

335

Intracellular heating of living cells through Néel relaxation of magnetic nanoparticles.  

PubMed

Maghemite and cobalt ferrite anionic magnetic nanoparticles enter tumor cells and can be used as heat sources when exposed to a high-frequency magnetic field. Comparative studies of the two particles enable to unravel the magnetic heating mechanisms (Néel relaxation vs. Brown relaxation) responsible for the cellular temperature rise, and also to establish a simple model, adjusted to the experimental results, allowing to predict the intracellular heating efficiency of iron oxide nanoparticles. Hence, we are able to derive the best nanoparticle design for a given material with a view to intracellular hyperthermia-based applications. PMID:17641885

Fortin, Jean-Paul; Gazeau, Florence; Wilhelm, Claire

2008-02-01

336

Controllable and facile fabrication of Fe nanoparticles/nanochains and their magnetic properties  

NASA Astrophysics Data System (ADS)

Fe nanoparticles and nanochains were prepared by a simple, accessible and pollution-free chemical reduction method. When the concentrations of addition agent NaOH and reagents were changed, the microstructure of Fe nanoparticles and Fe nanochains were distinctive. The magnetic properties of samples were researched, and the influence of the concentration of NaOH and Fe2+ on the microstructure and the magnetic properties of samples has been discussed detailedly. The control of magnetic properties of Fe nanoparticles and nanochains has been realized by adjusting the microstructure via changing the concentration of reagents and addition agent.

Tang, Hongzhe; Zhan, Xiaotong; Wu, Zhe; Du, Yu; Talbi, Abdelkrim; Pernod, Philippe

2015-03-01

337

Flash laser annealing for controlling size and shape of magnetic alloy nanoparticles  

PubMed Central

Summary We propose an original route to prepare magnetic alloy nanoparticles with uniform size and shape by using nanosecond annealing under pulsed laser irradiation. As demonstrated here on CoPt nanoparticles, flash laser annealing gives an unprecedented opportunity to control the size and the shape of bimetallic nanoparticles without changing their composition. The mechanisms involved in the complete reshaping of the nanoparticle thin films are discussed and it is also shown that order-disorder phase transformations occur under laser irradiation. This technique is then very interesting for magnetic alloy nanoparticles studies and applications because it opens up a new way to fabricate size-controlled spherical nanoparticles with narrow size dispersion. PMID:21977394

Ricolleau, Christian; Langlois, Cyril; Le Bouar, Yann; Loiseau, Annick

2010-01-01

338

Closed-loop magnetic separation of nanoparticles on a packed bed of spheres  

NASA Astrophysics Data System (ADS)

In this work, we consider magnetic separation of iron oxide nanoparticles when a nanoparticle suspension (diluted ferrofluid) passes through a closed-loop filter composed of a packed bed of micro-beads magnetized by an externally applied magnetic field. We show that the capture of nanoparticles of a size as small as 60 nm is easily achieved at low-to-moderate magnetic fields (16-32 kA/m) thanks to relatively strong magnetic interactions between them. The key parameter governing the capture process is the Mason number—the ratio of hydrodynamic-to-magnetic forces exerted to nanoparticles. The filter efficiency, ?, defined through the ratio of the inlet-to-outlet concentration shows a power-law dependency on Mason number, ??M a-0.83 , in the range of 102magnetic nanoparticles, followed by magnetic separation of the nanoparticles.

Magnet, Cécilia; Akouala, Mesferdon; Kuzhir, Pavel; Bossis, Georges; Zubarev, Andrey; Wereley, Norman M.

2015-05-01

339

Calibration Phantom for Quantitative Tomography Analysis of Biodistribution of Magnetic Nanoparticles  

NASA Astrophysics Data System (ADS)

Ferrofluids are being investigated for cancer treatments such as magnetic drug targeting (MDT) and magnetic heating treatments with the aim of treating the cancer locally, since magnetic nanoparticles with attached drugs are concentrated within the target region. Thus, the side effects are considerably reduced. One of the crucial factors for the success of these therapies is the magnetic nanoparticle distribution. Microcomputed X-ray tomography (X?CT) has been introduced as adequate technique for non-destructive three-dimensional analysis of biological samples enriched with magnetic nanoparticles. The biological tissue specimens, in this case tumor bearing mice after intra-tumoral magnetic nanoparticle injection, have been analyzed by means of X?CT. Complementary measurements have been performed by magnetorelaxometry (MRX). This technique enables a sensitive quantification of magnetic nanoparticles down to few nanograms. For multi-phase samples, such as biological tissue enriched with magnetic nanoparticles the polychromasy and beam hardening artifacts occurring in X?CT with conventional X-ray tubes cause severe problems for quantitative density determination. This problem requires an appropriate calibration of the polychromatic tomography equipment enabling a semi-quantitative analysis of the data. For this purpose a phantom system has been implemented. These phantoms consist of a tissue substitute containing different amounts of magnetic nanoparticles. Since the attenuation of the beam also depends on the thickness i.e. the path length of the beam transmitting the object, the reference sample has been defined to a cone shape. Thus, with one phantom the information about the magnetic nanoparticle concentration as well as the attenuation in dependence of the path length can be determined. Two phantom systems will be presented, one based on agarose-gel and one based on soap.

Rahn, Helen; Kettering, Melanie; Richter, Heike; Hilger, Ingrid; Trahms, Lutz; Odenbach, Stefan

2010-12-01

340

A Magnetic Nanoparticle-Based Multiple-Gene Delivery System for Transfection of Porcine Kidney Cells  

PubMed Central

Superparamagnetic nanoparticles are promising candidates for gene delivery into mammalian somatic cells and may be useful for reproductive cloning using the somatic cell nuclear transfer technique. However, limited investigations of their potential applications in animal genetics and breeding, particularly multiple-gene delivery by magnetofection, have been performed. Here, we developed a stable, targetable and convenient system for delivering multiple genes into the nuclei of porcine somatic cells using magnetic Fe3O4 nanoparticles as gene carriers. After surface modification by polyethylenimine, the spherical magnetic Fe3O4 nanoparticles showed strong binding affinity for DNA plasmids expressing the genes encoding a green (DNAGFP) or red (DNADsRed) fluorescent protein. At weight ratios of DNAGFP or DNADsRed to magnetic nanoparticles lower than or equal to 10?1 or 5?1, respectively, the DNA molecules were completely bound by the magnetic nanoparticles. Atomic force microscopy analyses confirmed binding of the spherical magnetic nanoparticles to stretched DNA strands up to several hundred nanometers in length. As a result, stable and efficient co-expression of GFP and DsRed in porcine kidney PK-15 cells was achieved by magnetofection. The results presented here demonstrate the potential application of magnetic nanoparticles as an attractive delivery system for animal genetics and breeding studies. PMID:25048709

Wang, Yan; Cui, Haixin; Li, Kui; Sun, Changjiao; Du, Wei; Cui, Jinhui; Zhao, Xiang; Chen, Wenjie

2014-01-01

341

Targeted fluorescent magnetic nanoparticles for imaging of human breast cancer  

PubMed Central

Magnetic nanoclusters coated with ruthenium (II) complexes doped with silica (fluorescent magnetic nanoparticles or FMNPs) could be used for magnetic resonance imaging (MRI) and optical imaging (OI) of human breast cancer. To achieve the targeting imaging of tumors, the peptide cyclic-arginine-glycine-aspartic acid (RGD) was chosen as the probe for specific targeting integrin ?v?3 over expressed in human breast cancer MDA-MB-231 cells. The cytotoxicity tests in vitro showed little toxicity of the synthesized RGD-FMNPs with the size of 150 nm. The in vivo study also showed no obvious acute toxicity after the injection of RGD-FMNPs in mice bearing MDA-MB-231 tumors. After 24 hours of co-culture with MDA-MB-231 cells, the cellular uptake of RGD-FMNPs significantly increased compared to that of FMNPs. T2-weighted (T2W) MRI demonstrated a negative enhancement in mice injected with RGD-FMNPs approximately three times of that injected with FMNPs (12.867 ± 0.451 ms vs. 4.833 ± 0.513 ms, P < 0.05). The Prussian blue staining results confirmed more RGD-FMNPs accumulated around the tumors than FMNPs. These results demonstrated the potential application of RGD-FMNPs as a targeting molecular probe for detection of breast cancer using MRI and OI. The synthesized RGD-FMNPs could be potentially used for biomedical imaging in the future. PMID:25663971

Sun, Jing; Teng, Zhao-Gang; Tian, Ying; Wang, Jian-Dong; Guo, Yang; Kim, Dong-Hyun; Larson, Andrew C; Lu, Guang-Ming

2014-01-01

342

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

343

Magnetic resonance imaging of microvessels using iron-oxide nanoparticles  

NASA Astrophysics Data System (ADS)

The visualization of microstructures including blood vessels with an inner overall cross-sectional area below approximately 200 ?m remains beyond the capabilities of current clinical imaging modalities. But with magnetic resonance (MR) imaging, magnetic entities cause susceptibility artifacts in the images by disrupting the homogeneous magnetic field in a much larger scale than their actual size. As validated in this paper through simulation and in-vitro experiments, these artifacts can serve as a source of contrast, enabling microvessels with an inner diameter below the spatial resolution of any medical imaging modalities to be visualized using a clinical MR scanner. For such experiments, micron-sized agglomerations of iron-oxide (Fe3O4) nanoparticles were injected in microchannels with internal diameters of 200 and 50 ?m equivalent to a narrower artery or a larger arteriole, and down to a smaller arteriole, respectively. The results show the feasibility of the proposed method for micro-particle detection and the visualization of microvessels using a 1.5 T clinical MR scanner. It was confirmed that the method is reproducible and accurate at the sub-pixel level.

Olamaei, N.; Cheriet, F.; Martel, S.

2013-03-01

344

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

345

Magnetic properties of polypyrrole-coated iron oxide nanoparticles  

NASA Astrophysics Data System (ADS)

Iron oxide nanoparticles were prepared using the sol-gel process. In situ polymerization of a pyrrole monomer in the presence of oxygen in an iron oxide-ethanol suspension resulted in an iron oxide polypyrrole nanocomposite. The structure and magnetic properties of the nanocomposites with varying pyrrole concentrations are investigated. X-ray diffraction studies indicate the presence of the ?-Fe2O3 phase for the concentrations investigated. FTIR studies confirm the presence of polypyrrole. TEM studies show agglomeration in uncoated samples and in samples with a lower concentration of polypyrrole. Agglomeration is greatly reduced for samples coated with a higher concentration of polypyrrole. The ac susceptibility measurements performed in the temperature range 77-300 K show the presence of blocking, indicating the superparamagnetic phase. The blocking temperature is found to depend on the pyrrole concentration. Monte Carlo studies for an array of polydispersed single domain magnetic particles, based on an interacting random anisotropy model, were also carried out, and the blocking temperatures obtained from the simulation of the field cooled-zero field cooled magnetization compare favourably with experimental results.

Sharma, Raksha; Lamba, Subhalakshmi; Annapoorni, S.

2005-09-01

346

Development of a magnetic nanoparticle susceptibility magnitude imaging array.  

PubMed

There are several emerging diagnostic and therapeutic applications of magnetic nanoparticles (mNPs) in medicine. This study examines the potential for developing an mNP imager that meets these emerging clinical needs with a low cost imaging solution that uses arrays of digitally controlled drive coils in a multiple-frequency, continuous-wave operating mode and compensated fluxgate magnetometers. The design approach is described and a mathematical model is developed to support measurement and imaging. A prototype is used to demonstrate active compensation of up to 185 times the primary applied magnetic field, depth sensitivity up to 2.5 cm (p < 0.01), and linearity over five dilutions (R(2) > 0.98, p < 0.001). System frequency responses show distinguishable readouts for iron oxide mNPs with single magnetic domain core diameters of 10 and 40 nm, and multi-domain mNPs with a hydrodynamic diameter of 100 nm. Tomographic images show a contrast-to-noise ratio of 23 for 0.5 ml of 12.5 mg Fe ml(-1) mNPs at 1 cm depth. A demonstration involving the injection of mNPs into pork sausage shows the potential for use in biological systems. These results indicate that the proposed mNP imaging approach can potentially be extended to a larger array system with higher-resolution. PMID:24504184

Ficko, Bradley W; Nadar, Priyanka M; Hoopes, P Jack; Diamond, Solomon G

2014-02-21

347

Development of a Magnetic Nanoparticle Susceptibility Magnitude Imaging Array  

PubMed Central

There are several emerging diagnostic and therapeutic applications of magnetic nanoparticles (mNPs) in medicine. This study examines the potential for developing an mNP imager that meets these emerging clinical needs with a low cost imaging solution that uses arrays of digitally controlled drive coils in a multiple-frequency, continuous-wave operating mode and compensated fluxgate magnetometers. The design approach is described and a mathematical model is developed to support measurement and imaging. A prototype is used to demonstrate active compensation of up to 185 times the primary applied magnetic field, depth sensitivity up to 2.5 cm (p < 0.01), and linearity over 5 dilutions (R2 > 0.98, p <0.001). System frequency responses show distinguishable readouts for iron oxide mNPs with single magnetic domain core diameters of 10 nm and 40 nm, and multi-domain mNPs with a hydrodynamic diameter of 100 nm. Tomographic images show a contrast-to-noise ratio of 23 for 0.5 ml of 12.5 mg Fe/ml mNPs at 1 cm depth. A demonstration involving the injection of mNPs into pork sausage shows the potential for use in biological systems. These results indicate that the proposed mNP imaging approach can potentially be extended to a larger array system with higher-resolution. PMID:24504184

Ficko, Bradley W.; Nadar, Priyanka M.; Hoopes, P. Jack; Diamond, Solomon G.

2014-01-01

348

Development of a magnetic nanoparticle susceptibility magnitude imaging array  

NASA Astrophysics Data System (ADS)

There are several emerging diagnostic and therapeutic applications of magnetic nanoparticles (mNPs) in medicine. This study examines the potential for developing an mNP imager that meets these emerging clinical needs with a low cost imaging solution that uses arrays of digitally controlled drive coils in a multiple-frequency, continuous-wave operating mode and compensated fluxgate magnetometers. The design approach is described and a mathematical model is developed to support measurement and imaging. A prototype is used to demonstrate active compensation of up to 185 times the primary applied magnetic field, depth sensitivity up to 2.5 cm (p < 0.01), and linearity over five dilutions (R2 > 0.98, p < 0.001). System frequency responses show distinguishable readouts for iron oxide mNPs with single magnetic domain core diameters of 10 and 40 nm, and multi-domain mNPs with a hydrodynamic diameter of 100 nm. Tomographic images show a contrast-to-noise ratio of 23 for 0.5 ml of 12.5 mg Fe ml-1 mNPs at 1 cm depth. A demonstration involving the injection of mNPs into pork sausage shows the potential for use in biological systems. These results indicate that the proposed mNP imaging approach can potentially be extended to a larger array system with higher-resolution.

Ficko, Bradley W.; Nadar, Priyanka M.; Hoopes, P. Jack; Diamond, Solomon G.

2014-02-01

349

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

350

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

351

Human-like collagen protein-coated magnetic nanoparticles with high magnetic hyperthermia performance and improved biocompatibility  

NASA Astrophysics Data System (ADS)

Human-like collagen (HLC)-coated monodispersed superparamagnetic Fe3O4 nanoparticles have been successfully prepared to investigate its effect on heat induction property and cell toxicity. After coating of HLC, the sample shows a faster rate of temperature increase under an alternating magnetic field although it has a reduced saturation magnetization. This is most probably a result of the effective heat conduction and good colloid stability due to the high charge of HLC on the surface. In addition, compared with Fe3O4 nanoparticles before coating with HLC, HLC-coated Fe3O4 nanoparticles do not induce notable cytotoxic effect at higher concentration which indicates that HLC-coated Fe3O4 nanoparticles has improved biocompatibility. Our results clearly show that Fe3O4 nanoparticles after coating with HLC not only possess effective heat induction for cancer treatment but also have improved biocompatibility for biomedicine applications.

Liu, Xiaoli; Zhang, Huan; Chang, Le; Yu, Baozhi; Liu, Qiuying; Wu, Jianpeng; Miao, Yuqing; Ma, Pei; Fan, Daidi; Fan, Haiming

2015-01-01

352

Formulation and In Vitro Characterization of Composite Biodegradable Magnetic Nanoparticles for Magnetically Guided Cell Delivery  

PubMed Central

Purpose Cells modified with magnetically responsive nanoparticles (MNP) can provide the basis for novel targeted therapeutic strategies. However, improvements are required in the MNP design and cell treatment protocols to provide adequate magnetic properties in balance with acceptable cell viability and function. This study focused on select variables controlling the uptake and cell compatibility of biodegradable polymer-based MNP in cultured endothelial cells. Methods Fluorescent-labeled MNP were formed using magnetite and polylactide as structural components. Their magnetically driven sedimentation and uptake were studied fluorimetrically relative to cell viability in comparison to non-magnetic control conditions. The utility of surface-activated MNP forming affinity complexes with replication-deficient adenovirus (Ad) for transduction achieved concomitantly with magnetic cell loading was examined using the green fluorescent protein reporter. Results A high-gradient magnetic field was essential for sedimentation and cell binding of albumin-stabilized MNP, the latter being rate-limiting in the MNP loading process. Cell loading up to 160 pg iron oxide per cell was achievable with cell viability >90%. Magnetically driven uptake of MNP-Ad complexes can provide high levels of transgene expression potentially useful for a combined cell/gene therapy. Conclusions Magnetically responsive endothelial cells for targeted delivery applications can be obtained rapidly and efficiently using composite biodegradable MNP. PMID:22274555

Alferiev, Ivan S.; Fishbein, Ilia; Tengood, Jillian E.; Folchman-Wagner, Zoë; Forbes, Scott P.; Levy, Robert J.

2012-01-01

353

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

354

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

355

Magnetic nanoparticles as markers for cellular MR imaging  

NASA Astrophysics Data System (ADS)

Cellular MR imaging is a rapidly growing field that aims to visualize targeted cells in living organisms. Superparamagnetic iron oxide nanoparticles, that induce a hypointense contrast on the MR images, have now widely been used to mark cells in vitro and in vivo. Following intravenous injection, the particles are rapidly taken up by phagocytic cells of the reticuloendothelial system, and imaging of this "macrophage activity" has been translated into the clinic for tumor staging of the liver and lymph nodes. A new, still experimental application of magnetic particles as cellular markers is its use to monitor cell migration and cell trafficking following labeling and transfer to living organisms. Further exploitation of this technique will allow a better understanding of the dynamics of in vivo cell biology as well as translation into the clinic to monitor (stem) cell-based therapies.

Bulte, Jeff W. M.

2005-03-01

356

A Novel Magnetic Nanoparticle Drug Carrier for Enhanced Cancer Chemotherapy  

PubMed Central

Background Magnetic nanoparticles (NPs) loaded with antitumor drugs in combination with an external magnetic field (EMF)-guided delivery can improve the efficacy of treatment and may decrease serious side effects. The purpose of this study was 1) to investigate application of PEG modified GMNPs (PGMNPs) as a drug carrier of the chemotherapy compound doxorubicin (DOX) in vitro; 2) to evaluate the therapeutic efficiency of DOX-conjugated PGMNPs (DOX-PGMNPs) using an EMF-guided delivery in vivo. Methods First, DOX-PGMNPs were synthesized and the cytotoxicity of DOX-PGMNPs was assessed in vitro. Second, upon intravenous administration of DOX-PMGPNs to H22 hepatoma cell tumor-bearing mice, the DOX biodistribution in different organs (tissues) was measured. The antitumor activity was evaluated using different treatment strategies such as DOX-PMGPNs or DOX-PMGPNs with an EMF-guided delivery (DOX-PGMNPs-M). Results The relative tumor volumes in DOX-PGMNPs-M, DOX-PGMNPs, and DOX groups were 5.46±1.48, 9.22±1.51, and 14.8±1.64, respectively (each p<0.05), following treatment for 33 days. The life span of tumor-bearing mice treated with DOX-PGMNPs-M, DOX-PGMNPs, and DOX were 74.8±9.95, 66.1±13.5, and 31.3±3.31 days, respectively (each p<0.05). Conclusion This simple and adaptive nanoparticle design may accommodate chemotherapy for drug delivery optimization and in vivo drug-target definition in system biology profiling, increasing the margin of safety in treatment of cancers in the near future. PMID:23056167

Guo, Lili; Zhu, Jingjing; Peng, Mingli; Vermorken, Alphonsus J. M.; Van de Ven, Wim J. M.; Chen, Chao; Cui, Yali

2012-01-01

357

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

358

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

PubMed Central

Molecular imaging allows clinicians to visualize the progression of tumours and obtain relevant information for patient diagnosis and treatment1. 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 expression2. 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 ligand3,4,5 and reduce the ability of the nanoparticle to bind to a finite number of receptors on cells6. Increasing the number of nanoparticles delivered to cells by each targeting molecule would lead to higher signal-to-noise ratios and 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. PMID:22983492

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

2014-01-01

359

Physiological effects of magnetic iron oxide nanoparticles towards watermelon.  

PubMed

Nanoparticles (NPs) have been exploited in a diverse range of products in the past decade or so. However, the biosafety/environmental impact or legislation pertaining to this newly created, highly functional composites containing NPs (otherwise called nanomaterials) is generally lagging behind their technological innovation. To advance the agenda in this area, our current primary interest is focused on using crops as model systems as they have very close relationship with us. Thus, the objective of the present study was to evaluate the biological effects of magnetic iron oxide nanoparticles towards watermelon seedlings. We have systematically studied the physiological effects of Fe2O3 nanoparticles (nano-Fe2O3) on watermelon, and present the first evidence that a significant amount of Fe2O3 nanoparticles suspended in a liquid medium can be taken up by watermelon plants and translocated throughout the plant tissues. Changes in important physiological indicators, such as root activity, activity of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD), chlorophyll and malondialdehyde (MDA) contents, ferric reductase activity, root apoplastic iron content were clearly presented. Different concentrations of nano-Fe2O3 all increased seed germination, seedling growth, and enhanced physiological function to some degree; and the positive effects increased quickly and then slowed with an increase in the treatment concentrations. Changes in CAT, SOD and POD activities due to nano-Fe2O3 were significantly larger than that of the control. The 20 mg/L treatment had the most obvious effect on the increase of root activity. Ferric reductase activity, root apoplastic iron content, and watermelon biomass were significantly affected by exposure to nano-Fe2O3. Results of statistical analysis showed that there were significant differences in all the above indexes between the treatment at optimal concentration and the control. This proved that the proper concentration of nano-Fe2O3 could not only increase seed germination and seedling growth, but also ultimately improve physiological function and resistance to environmental stresses of watermelon. PMID:23882795

Li, Junli; Chang, Peter R; Huang, Jin; Wang, Yunqiang; Yuan, Hong; Ren, Hongxuan

2013-08-01

360

Synthesis and characterization of Magnetic Nanoparticles and Their Reinforcement in Polyurethane Film  

E-print Network

: magnetite nanoparticles, synthesis, PU composite films Abstract: Magnetic nanoparticles have attracted Film X.X. Xu 1,a and Y.F. Zheng1,2,b 1 Center for Biomedical Materials and Engineering, Harbin is one of the most biocompatible polymers and has been used widely in vivo. In this paper, the magnetite

Zheng, Yufeng

361

Magnetic, electric and thermal properties of cobalt ferrite nanoparticles , N. Mlikia  

E-print Network

1 Magnetic, electric and thermal properties of cobalt ferrite nanoparticles L.Ajroudia , N. Mlikia]. The elaboration route developed led to chemically homogeneous spinel cobalt ferrites, with mean size ranging from. The sensing properties of cobalt ferrite nanoparticles were investigated, and different resistance variations

Paris-Sud XI, Université de

362

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

363

Bare Magnetic Nanoparticles: Sustainable Synthesis and Applications in Catalytic Organic Transformations  

EPA Science Inventory

Magnetic nanoparticles have become increasingly prominent in the field of catalysis over the last decade as they combine interesting reactivity with an easy, economical and environmentally benign mode of recovery. Early strategies focused on the use of such nanoparticles only as ...

364

One-pot green synthesis of biocompatible arginine-stabilized magnetic nanoparticles.  

PubMed

A green one-step approach has been developed for the synthesis of amino-functionalized magnetite nanoparticles. The synthesis was accomplished by simply mixing FeCl2 with arginine under ambient conditions. It was found that the Fe2+/arginine molar ratio, reaction duration and temperature greatly influence the size, morphology and composition of magnetic nanoparticles. The arginine-stabilized magnetic nanoparticles were characterized by transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy techniques. The results show that the prepared nanoparticles are spherically shaped with a nearly uniform size distribution and pure magnetite phase. The presence of arginine on the magnetic nanoparticle surface has been confirmed and the amount of surface arginine varies with the Fe2+/arginine molar ratio. The surface amine densities are calculated to be 5.60 and 7.84 micromol mg(-1) for magnetic nanoparticles prepared at 1:1 and 1:2 Fe2+/arginine molar ratio, respectively. The as-synthesized nanoparticles show superparamagnetic behavior at room temperature and good solubility in water. In addition, using a similar synthesis procedure, we have been able to synthesize superparamagnetic manganese and cobalt ferrite nanoparticles. PMID:19847022

Wang, Zhongjun; Zhu, Hui; Wang, Xiaolei; Yang, Fan; Yang, Xiurong

2009-11-18

365

Effects of surfactant friction on Brownian magnetic relaxation in nanoparticle ferrofluids  

E-print Network

Effects of surfactant friction on Brownian magnetic relaxation in nanoparticle ferrofluids-fluids of surfactant-coated Co nanoparticles, 20 nm in diameter, in dichlorobenzene in a wide concentration range with oleic acid. It is shown that at a close distance between particles surfactant friction leads

Krishnan, Kannan M.

366

Particle size effect on phase and magnetic properties of polymer-coated magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Polymer-coated magnetic nanoparticles are hi-tech materials with ample applications in the field of biomedicine for the treatment of cancer and targeted drug delivery. In this study, magnetic nanoparticles were synthesized by chemical reduction of FeCl 2 solution with sodium borohydride and coated with amine-terminated polyethylene glycol (aPEG). By varying the concentration of the reactants, the particle size and the crystallinity of the particles were varied. The particle size was found to increase from 6 to 20 nm and the structure becomes amorphous-like with increase in the molar concentration of the reactant. The magnetization at 1 T field ( M1T) for all samples is > 45 emu/g while the coercivity is in the range of 100-350 Oe. When the ethanol-suspended particles are subjected to an alternating magnetic field of 4 Oe at 500 kHz, the temperature is increased to a maximum normalized temperature (3.8 °C/mg) with decreasing particle size.

Balakrishnan, Srinivasan; Bonder, Michael J.; Hadjipanayis, George C.

2009-01-01

367

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

368

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

369

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

Microsoft Academic Search

Magnetometry was used to determine the magnetic properties of maghemite (gamma-Fe2O3) nanoparticles formed within Listeria innocua protein cage. The electron magnetic resonance spectrum shows the presence of at least two magnetization components. The magnetization curves are explained by a sum of two Langevin functions in which each filled protein cage contains both a large magnetic iron oxide core plus an

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

2010-01-01

370

Magnetic resonance of polyaspartic acid-coated magnetite nanoparticles administered in mice  

Microsoft Academic Search

Magnetic resonance (MR) was used in the biodistribution investigation of magnetic nanoparticles (MNPs) surface-coated with polyaspartic acid (PAMF), developed as a biocompatible magnetic fluid (BMF) sample. The data allowed us to obtain the kinetic parameters for MNP disposition from the blood and its uptake by the liver, spleen, and lungs. Light microscopy confirmed the MR results. Genetic and toxicity tests

N. Sadeghiani; L. S. Barbosa; M. H. A. Guedes; S. B. Chaves; J. G. Santos; O. Silva; F. Pelegrini; R. B. Azevedo; P. C. Morais; Z. G. M. Lacava

2005-01-01

371

Physical properties of magnetic macromolecule-metal and macromolecule-metal oxide nanoparticle complexes  

Microsoft Academic Search

Magnetic nanoparticles are of considerable interest owing to their potential applications in biotechnology and the magnetic recording industry. Iron oxides have received much attention owing to their oxidative stability and biocompatibility; however, other transition metals and their alloys are also under investigation. Cobalt has one of the largest magnetic susceptibilities of these materials, but it readily oxidizes upon exposure to

Michael Andrew Zalich

2005-01-01

372

Synthesis and surface modification of magnetic nanoparticles for in vivo biomedical applications  

Microsoft Academic Search

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 to serve as contrast agents for magnetic resonance imaging (MRI) and as carriers for drug delivery. Recent advances in nanotechnology have improved the ability to engineer the features and properties of MNPs allowing them

Conroy Ghin Chee Sun

2008-01-01

373

Intracellular performance of tailored nanoparticle tracers in magnetic particle imaging Hamed Arami and Kannan M. Krishnan  

E-print Network

tracers in different environments Med. Phys. 40, 071904 (2013); 10.1118/1.4810962 Structural and magnetic magnetometry, magnetic particle spectroscopy, transmission electron microscopy, and dynamic light scatteringIntracellular performance of tailored nanoparticle tracers in magnetic particle imaging Hamed Arami

Krishnan, Kannan M.

374

Emulsion-Based Synthesis of Reversibly Swellable, Magnetic Nanoparticle-Embedded Polymer Microcapsules  

E-print Network

Emulsion-Based Synthesis of Reversibly Swellable, Magnetic Nanoparticle-Embedded Polymer mixture containing liquid prepolymer and MPs in chloroform solution, double emulsions comprising emulsions converted to microcapsules with a polymerized composite shell. The evolution from the double

Velev, Orlin D.

375

Synthesis of highly magnetic graphite-encapsulated FeCo nanoparticles using a hydrothermal process  

NASA Astrophysics Data System (ADS)

The graphite encapsulation of metal alloy magnetic nanoparticles has attracted attention for biological applications because of the high magnetization of the encapsulated particles. However, most of the synthetic methods have limitations in terms of scalability and economics because of the demanding synthetic conditions and low yields. Here, we show that well controlled graphite-encapsulated FeCo core-shell nanoparticles can be synthesized by a hydrothermal method, simply by mixing Fe/Co with sucrose as a carbon source. Various Fe/Co metal ratios were used to determine the compositional dependence of the saturation magnetization and relaxivity coefficient. Transmission electron microscopy indicated that the particle sizes were 7 nm. In order to test the capability of graphite-encapsulated FeCo nanoparticles as magnetic resonance imaging (MRI) contrast agents, these nanoparticles were solubilized in water by the nonspecific physical adsorption of sodium dodecylbenzene sulfonate.

Lee, Seung Jae; Cho, Jee-Hyun; Lee, Chulhyun; Cho, Janggeun; Kim, Yong-Rok; Park, Joung Kyu

2011-09-01

376

Selective growth of magnetic nanoparticles in domains of block copolymer films, and in polyelectrolyte multilayers  

E-print Network

Nonagglomerated cobalt, iron, iron-cobalt, and cobalt-nickel alloy nanoparticles, some of which exhibit significant room-temperature magnetic coercivity, have been produced by thermal decomposition of organometallic complexes ...

Abes, Jeff I., 1975-

2003-01-01

377

Magnetic nanoparticles : synthesis, characterization, applications and systematic study of exchanging biasing  

E-print Network

We systematically investigated the magnetic properties of colloidal cobalt nanoparticles after three extents of oxidation: The native sample has a thin (1.0 nm) CoO shell and exhibits no exchange biasing. The purposefully ...

Tracy, Joseph B. (Joseph Benjamin)

2005-01-01

378

Fullerene C60 functionalized ?-Fe2O3 magnetic nanoparticle: Synthesis, characterization, and biomedical applications.  

PubMed

Hybrid magnetic nanoparticles composed from C60 fullerene and ?-Fe2O3 were synthesized by hydrothermal method. XRD, FT-IR, VSM, SEM, and HR-TEM were employed for characterizations. The magnetic saturation value of C60-?-Fe2O3 magnetic nanoparticles was 66.5 emu g(- 1). Concentration of Fe in nanoparticles asdetermined by ICP-OES was 40.7% Fe. Particle size of C60-?-Fe2O3 magnetic nanoparticles was smaller than 10 nm. Maximum adsorption capacity of C60-?-Fe2O3 for flurbiprofen, a non-steroidal anti-inflammatory drug, was calculated from Langmuir isotherm as 142.9 mg g(- 1). PMID:25118710

K?l?nç, Ersin

2014-08-14

379

Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles  

NASA Astrophysics Data System (ADS)

In the present study, monodispersed CeO2 nanoparticles (NPs) of size 8.5 ± 1.0, 11.4 ± 1.0 and 15.4 ± 1.0 nm were synthesized using the sol-gel method. Size-dependent structural, optical and magnetic properties of as-prepared samples were investigated by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), high resolution transmission electron microscopy (HR-TEM), ultra-violet visible (UV-VIS) spectroscopy, Raman spectroscopy and vibrating sample magnetometer (VSM) measurements. The value of optical band gap is calculated for each particle size. The decrease in the value of optical band gap with increase of particle size may be attributed to the quantum confinement, which causes to produce localized states created by the oxygen vacancies due to the conversion of Ce4+ into Ce3+ at higher calcination temperature. The Raman spectra showed a peak at ˜461 cm-1 for the particle size 8.5 nm, which is attributed to the 1LO phonon mode. The shift in the Raman peak could be due to lattice strain developed due to variation in particle size. Weak ferromagnetism at room temperature is observed for each particle size. The values of saturation magnetization (Ms), coercivity (Hc) and retentivity (Mr) are increased with increase of particle size. The increase of Ms and Mr for larger particle size may be explained by increase of density of oxygen vacancies at higher calcination temperature. The latter causes high concentrations of Ce3+ ions activate more coupling between the individual magnetic moments of the Ce ions, leading to an increase of Ms value with the particle size. Moreover, the oxygen vacancies may also produce magnetic moment by polarizing spins of f electrons of cerium (Ce) ions located around oxygen vacancies, which causes ferromagnetism in pure CeO2 samples.

Kumar, Sumeet; Srivastava, Manish; Singh, Jay; Layek, Samar; Yashpal, Madhu; Materny, Arnulf; Ojha, Animesh K.

2015-02-01

380

Experimental investigation of magnetically actuated separation using tangential microfluidic channels and magnetic nanoparticles.  

PubMed

A novel continuous switching/separation scheme of magnetic nanoparticles (MNPs) in a sub-microlitre fluid volume surrounded by neodymium permanent magnet is studied in this work using tangential microfluidic channels. Polydimethylsiloxane tangential microchannels are fabricated using a novel micromoulding technique that can be done without a clean room and at much lower cost and time. Negligible switching of MNPs is seen in the absence of magnetic field, whereas 90% of switching is observed in the presence of magnetic field. The flow rate of MNPs solution had dramatic impact on separation performance. An optimum value of the flow rate is found that resulted in providing effective MNP separation at much faster rate. Separation performance is also investigated for a mixture containing non-magnetic polystyrene particles and MNPs. It is found that MNPs preferentially moved from lower microchannel to upper microchannel resulting in efficient separation. The proof-of-concept experiments performed in this work demonstrates that microfluidic bioseparation can be efficiently achieved using functionalised MNPs, together with tangential microchannels, appropriate magnetic field strength and optimum flow rates. This work verifies that a simple low-cost magnetic switching scheme can be potentially of great utility for the separation and detection of biomolecules in microfluidic lab-on-a-chip systems. PMID:25014081

Munir, Ahsan; Zhu, Zanzan; Wang, Jianlong; Zhou, Hong Susan

2014-06-01

381

The use of magnetite nanoparticles for implant-assisted magnetic drug targeting in thrombolytic therapy.  

PubMed

Implant-assisted targeting of magnetic particles under the influence of an external magnetic field has previously been verified through mathematical modeling, in vitro studies, and in vivo studies on rat carotid arteries as a feasible method for localized drug delivery. The present study focuses on the development of nanoparticles for the treatment of in-stent thrombosis. Magnetic nanoparticles in the size-range 10-30 nm were synthesized in a one-pot procedure by precipitation of ferrous hydroxide followed by oxidation to magnetite. The nanoparticles were silanized with tetraethyl orthosilicate in the presence of triethylene glycol and/or polyethylene glycol. The surface coated magnetite nanoparticles were activated with either N-hydroxysulfosuccinimide or tresyl chloride for covalent immobilization of tissue plasminogen activator (tPA). Hysteresis loops showed saturation magnetizations of 55.8, 44.1, and 43.0 emu/g for the naked nanoparticles, the surface coated nanoparticles, and the tPA-nanoparticle conjugates, respectively. The hemolytic activity of the nanoparticles in blood was negligible. An initial in vivo biocompatibility test in pig, carried out by intravascular injection of the nanoparticles in a stented brachial artery, showed no short-term adverse effects. In vitro evaluation in a flow-through model proved that the nanoparticles were captured efficiently to the surface of a ferromagnetic coiled wire at the fluid velocities typical for human arteries. A preliminary test of the tPA-nanoparticle conjugates in a pig model suggested that the conjugates may be used for treatment of in-stent thrombosis in coronary arteries. PMID:20732712

Kempe, Maria; Kempe, Henrik; Snowball, Ian; Wallén, Rita; Arza, Carlos Rodriguez; Götberg, Matthias; Olsson, Tommy

2010-12-01

382

High-Field Gradient Permanent Micromagnets for Targeted Drug Delivery with Magnetic Nanoparticles  

NASA Astrophysics Data System (ADS)

We analytically investigate several micromagnetic systems aimed at the optimization of drug and gene delivery processes and show their applicability to the controlled positioning of magnetic nanoparticles. The systems considered are: i) a square array of cylindrical microneedles, ii) a planar stepped array of magnets, and iii) a Halbach array of micromagnets. We calculate spatial distributions of force components acting on a magnetic nanoparticle and the field gradients produced by these magnetic configurations. These calculations show that array geometries tend to enhance the field gradients and forces that can be obtained from a given material. The benefits of the proposed micromagnetic systems—tunability, scalability, and ability of creation of magnetic flux distributions with high-gradient areas allowing precise focusing of magnetic nanoparticles (MNPs)—are also discussed.

Zablotskii, Vitalii; Pastor, José Martín; Larumbe, Silvia; Pérez-Landazábal, José Ignacio; Recarte, Vicente; Gómez-Polo, Cristina

2010-12-01

383

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

384

Static and dynamic magnetic properties of Co 2 Z barium ferrite nanoparticle composites  

Microsoft Academic Search

The static, dynamic and attenuation properties of Co2Z barium ferrites and Co2Z composites have been studied. The results showed that both static and dynamic magnetic properties are significantly different for large particles and nanoparticles. As compared to large particles, Co2Z nanoparticles have a small saturation magnetization Ms, large coercivity Hc, small permeability µ'0 and µ''max, but high resonance frequency fR.

Z. W. Li; L. Chen; C. K. Ong; Z. Yang

2005-01-01

385

Coercivity enhancement in Nd-Fe-B sintered permanent magnet doped with Pr nanoparticles  

NASA Astrophysics Data System (ADS)

Nd-Fe-B permanent magnets doped with a small amount of praseodymium (Pr) nanoparticles were prepared by conventional sintering method. Effects of the Pr nanoparticles doping amount and the sintering temperature on the magnetic properties of the magnets were studied. As the doping amount increases, the coercivity of the magnets rises gradually, while the remanence and the maximum energy product of the magnets rise first, peak at 1.0 wt. % of Pr nanoparticles doping, then drop. The optimal sintering temperature was determined as 1040 °C. Under optimal doping amount and sintering temperature, the Nd-Fe-B magnet bears good magnetic properties of Br of 1.386 T, Hci of 1170 kA/m and (BH)max of 371 kJ/m3, which are better than the Pr-free magnet's magnetic properties of Br of 1.358 T, Hci of 1097 kA/m and (BH)max of 354 kJ/m3, suggesting the doping of Pr nanoparticles is a promising way to enhance the magnetic properties of sintered Nd-Fe-B magnets.

Sun, H.; Liu, W. Q.; Zhang, X. R.; Yue, M.; Zhang, D. T.; Zhang, J. X.

2011-04-01

386

Influence of surface spins on the magnetization of fine maghemite nanoparticles  

NASA Astrophysics Data System (ADS)

Influence of surface spins on magnetization of maghemite nanoparticles have been studied by using SQUID measurements and also comparison done with theoretical simulations. Surface spin disorder arises in these nanoparticles due to the randomness of surface spins. A model of AC-susceptibility has been used to investigate the experimental results. The comparison between experiment and theory signifies the presence of large effective anisotropy and freezing effects on the surface of maghemite nanoparticles. The enhanced effective anisotropy constant of these nanoparticles as compared to bulk maghemite is due to presence of disordered surface spins.

Nadeem, K.; Krenn, H.; Szabó, D. V.

2013-12-01

387

Influence of surface spins on the magnetization of fine maghemite nanoparticles  

SciTech Connect

Influence of surface spins on magnetization of maghemite nanoparticles have been studied by using SQUID measurements and also comparison done with theoretical simulations. Surface spin disorder arises in these nanoparticles due to the randomness of surface spins. A model of AC-susceptibility has been used to investigate the experimental results. The comparison between experiment and theory signifies the presence of large effective anisotropy and freezing effects on the surface of maghemite nanoparticles. The enhanced effective anisotropy constant of these nanoparticles as compared to bulk maghemite is due to presence of disordered surface spins.

Nadeem, K. [Department of Physics, International Islamic University, H-10, Islamabad (Pakistan); Krenn, H. [Institute of Physics, Karl-Franzens University Graz, Universitätsplatz 5, A-8010 Graz (Austria); Szabó, D. V. [Institute for Advanced Materials-Materials Process Technology, Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe (Germany)

2013-12-16

388

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

389

Ectoenzyme switches the surface of magnetic nanoparticles for selective binding of cancer cells.  

PubMed

Enzymatic switch, such as phosphorylation and dephosphorylation of proteins, is the most important mechanism for cellular signal transductions. Inspired by Nature and encouraged by our recent unexpected observation of the dephosphorylation of d-tyrosine phosphate-contain small peptides, we modify the surface of magnetic nanoparticles (MNP) with d-tyrosine phosphate that is a substrate of alkaline phosphatase (ALP). Our studies find that ALP is able to remove the phosphate groups from the magnetic nanoparticles. Most importantly, placental alkaline phosphatase (ALPP), an ectoenzyme that locates on cell surface with catalytic domains outside the plasma membrane and is overexpressed on many cancer cells, dephosphorylate the d-tyrosine phosphates on the surface of the magnetic nanoparticle and enable the magnetic nanoparticles to adhere selectively to the cancer cells, such as HeLa cells. Unlikely commonly used antibodies, the selectivity of the magnetic nanoparticles to cancer cells originates from the enzymatic reaction catalyzed by ALPP. The use of enzymatic reaction to modulate the surface of various nanostructures may lead to a general method to broadly target cancer cells without relying on specific ligand-receptor interactions (e.g., antibodies). This work, thus, illustrates a fundamentally new concept to allow cells to actively engineer the surface of colloids materials, such as magnetic nanoparticles, for various applications. PMID:25586118

Du, Xuewen; Zhou, Jie; Xu, Bing

2015-06-01

390

Effects silver nanoparticles and magnetic field on growth of fodder maize (Zea mays L.).  

PubMed

Two experiments were done in 2008 and 2009 to study the effects of magnetic field and silver nanoparticles on fodder maize (Zea mays L.). These experiments were done with seven treatments based on a randomized complete block design in four replications. The treatments were as follows: magnetic field and silver nanoparticles + Kemira fertilizer (T1), magnetic field and silver nanoparticles + Humax fertilizer (T2), magnetic field and silver nanoparticles (T3), Kemira fertilizer (T4), Librel fertilizer (T5), Humax fertilizer (T6), and a control (T7). Results showed that fresh yield was higher in treatments T3 and T4. Treatments T3 and T4 had increased maize fresh yields of 35 and 17.5 % in comparison to the control, respectively. The dry matter yield of those plants exposed to magnetic field and silver nanoparticles was significantly higher than that from any of the other treatments. Magnetic field and silver nanoparticle treatments (T3 and T1) showed higher percentages for ears, and the lowest percentages were found in treatments T7 and T5. In general, the soil conditions for crop growth were more favorable in 2009 than in 2008, which caused the maize to respond better to treatments tested in the study; therefore, treatments had more significant effects on studied traits in 2008 than in 2009. PMID:22555519

Berahmand, Ali Asghar; Ghafariyan Panahi, Ali; Sahabi, Hossein; Feizi, Hassan; Rezvani Moghaddam, Parviz; Shahtahmassebi, Nasser; Fotovat, Amir; Karimpour, Hossein; Gallehgir, Omran

2012-12-01

391

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

392

Use of magnetic nanoparticle heating in the treatment of breast cancer.  

PubMed

Magnetic nanoparticles are promising tools for the minimal invasive elimination of small tumours in the breast using magnetically-induced heating. The approach complies with the increasing demand for breast conserving therapies and has the advantage of offering a selective and refined tuning of the degree of energy deposition allowing an adequate temperature control at the target. The biophysical basis of the approach, the magnetic and structural properties of magnetic nanoparticles are reviewed. Results with model targets and in vivo experiments in laboratory animals are reported. PMID:16441156

Hilger, I; Hergt, R; Kaiser, W A

2005-02-01

393

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

394

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

SciTech Connect

Iron oxide nanoparticles with mean diameter ranging from 7 to 20 nm were synthesized using two routes: the precipitation method in controlled atmosphere and a reduction–precipitation method under air, in some cases followed by a hydrothermal treatment. The smallest nanoparticles were obtained by the reduction–precipitation method. In order to establish the composition of the iron oxide nanoparticles and its relation with size, the morphological, structural and magnetic properties of the prepared samples were investigated using X-ray diffraction, transmission electron microscopy, Mössbauer spectroscopy and SQUID magnetometry. The results allow to conclude that the nanoparticles can be essentially described as Fe{sub 3?x}O{sub 4}, x decreasing with the particle size increase. The composition and magnetic behavior of the synthesized iron oxide nanoparticles are directly related with their size. The overall results are compatible with a core@shell structure model, where a magnetite core is surrounded by an oxidized magnetite layer (labeled as maghemite), the magnetite core dimension depending on the average particle size. - Graphical abstract: TEM images and Mössbauer spectroscopy spectra of Fe{sub 3?x}O{sub 4} samples with different sizes. Highlights: ? Fe{sub 3?x}O{sub 4} nanoparticles with a mean size between 7 and 20 nm were synthesized. ? The smallest nanoparticles were obtained by a reduction precipitation method, under air. ? The increase of particles size was succeeded using a hydrothermal treatment at 150 °C. ? The magnetic properties of the nanoparticles are directly related with their size.

Carvalho, M.D., E-mail: mdcarvalho@fc.ul.pt [CCMM/Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, C8, 1749-016 Lisboa (Portugal); Henriques, F. [CCMM/Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, C8, 1749-016 Lisboa (Portugal); Ferreira, L.P. [CFMC/Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal); Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-516 Coimbra (Portugal); Godinho, M.; Cruz, M.M. [CFMC/Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal)

2013-05-15

395

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

396

Hydroxybutyl Chitosan Polymer-Mediated CD133 Antibody Coating of Metallic Stents to Reduce Restenosis in a Porcine Model of Atherosclerosis.  

PubMed

Antibody-coated stents to capture circulating endothelial progenitor cells (EPCs) for re-endothelialization appear to be a novel therapeutic option for the treatment of atherosclerotic disease. Hydroxybutyl chitosan (HBC), a linear polysaccharide made from shrimps and other crustacean shells, is biocompatible, nontoxic, and hydrophilic, making it ideal for biomedical applications. In this study, HBC was explored for the immobilization of anti-CD133 antibodies. We demonstrated that CD133 antibodies mediated by HBC were successfully coated on cobalt-chromium alloy discs and metal stents. The coating was homogeneous and smooth as shown by electronic microscopy analysis. Balloon expansion of coated stents did not cause cracking or peeling. The HBC discs promoted CD133+ EPCs and human umbilical vein endothelial cell growth in vitro. The CD133 antibody-coated but not bare discs bound CD133+ EPCs in vitro. Implantation of CD133 antibody-coated stents significantly inhibited intimal hyperplasia and reduced restenosis compared with implantation of bare stents in a porcine model of atherosclerosis. These findings suggest HBC is a valuable anchoring agent that can be applied for bioactive coating of stents and that CD133 antibody-coated stents might be a potential therapeutic alternative for the treatment of atherosclerotic disease. PMID:25412893

Li, Jian; Zhang, Qiuwang; Li, Dan; An, Yi; Kutryk, Michael B J

2015-05-01

397

Effect of Anti-ApoA-I Antibody-Coating of Stents on Neointima Formation in a Rabbit Balloon-Injury Model  

PubMed Central

Background and Aims Since high-density lipoprotein (HDL) has pro-endothelial and anti-thrombotic effects, a HDL recruiting stent may prevent restenosis. In the present study we address the functional characteristics of an apolipoprotein A-I (ApoA-I) antibody coating in vitro. Subsequently, we tested its biological performance applied on stents in vivo in rabbits. Materials and Methods The impact of anti ApoA-I- versus apoB-antibody coated stainless steel discs were evaluated in vitro for endothelial cell adhesion, thrombin generation and platelet adhesion. In vivo, response to injury in the iliac artery of New Zealand white rabbits was used as read out comparing apoA-I-coated versus bare metal stents. Results ApoA-I antibody coated metal discs showed increased endothelial cell adhesion and proliferation and decreased thrombin generation and platelet adhesion, compared to control discs. In vivo, no difference was observed between ApoA-I and BMS stents in lumen stenosis (23.3±13.8% versus 23.3±11.3%, p=0.77) or intima surface area (0.81±0.62 mm2 vs 0.84±0.55 mm2, p=0.85). Immunohistochemistry also revealed no differences in cell proliferation, fibrin deposition, inflammation and endothelialization. Conclusion ApoA-I antibody coating has potent pro-endothelial and anti-thrombotic effects in vitro, but failed to enhance stent performance in a balloon injury rabbit model in vivo. PMID:25821966

Koole, Leo H.; de Winter, Robbert J.; van der Wal, Allard C.; de Vries, Carlie J. M.; Tak, Paul P.; Bisoendial, Radjesh J.; Stroes, Erik S. G.; Rotmans, Joris I.

2015-01-01

398

Application of computed tomography images in the evaluation of magnetic nanoparticles biodistribution  

NASA Astrophysics Data System (ADS)

In this work we evaluate the effectiveness of computed tomography images as a tool to determine magnetic nanoparticle biodistribution over biological tissues. For this purpose, tomography images for magnetic nanoparticles, composed of Fe 3O 4, coated with 2,3-dimercaptosuccinic acid (DMSA), were generated at several material concentrations. The comparison of CT numbers, calculated from these images generated at clinical conditions, with typical CT numbers for biological tissues, shows that the detection of nanoparticle in most tissues is only possible for high material concentrations.

Dias, Argleydson Leão; Künzel, Roseli; Levenhagen, Ronaldo Savarino; Okuno, Emico

2010-08-01

399

Size-dependent magnetic properties of single-crystalline multiferroic BiFeO3 nanoparticles.  

PubMed

As-prepared, single-crystalline bismuth ferrite nanoparticles show strong size-dependent magnetic properties that correlate with: (a) increased suppression of the known spiral spin structure (period length of approximately 62 nm) with decreasing nanoparticle size and (b) uncompensated spins and strain anisotropies at the surface. Zero-field-cooled and field-cooled magnetization curves exhibit spin-glass freezing behavior due to a complex interplay between finite size effects, interparticle interactions, and a random distribution of anisotropy axes in our nanoparticle assemblies. PMID:17324002

Park, Tae-Jin; Papaefthymiou, Georgia C; Viescas, Arthur J; Moodenbaugh, Arnold R; Wong, Stanislaus S

2007-03-01

400

Characterization of magnetite nanoparticles for SQUID-relaxometry and magnetic needle biopsy  

NASA Astrophysics Data System (ADS)

Magnetite nanoparticles (Chemicell SiMAG-TCL) were characterized by SQUID-relaxometry, susceptometry, and TEM. The magnetization detected by SQUID-relaxometry was 0.33% of that detected by susceptometry, indicating that the sensitivity of SQUID-relaxometry could be significantly increased through improved control of nanoparticle size. The relaxometry data were analyzed by the moment superposition model (MSM) to determine the distribution of nanoparticle moments. Analysis of the binding of CD34-conjugated nanoparticles to U937 leukemia cells revealed 60,000 nanoparticles per cell, which were collected from whole blood using a prototype magnetic biopsy needle, with a capture efficiency of >65% from a 750 ?l sample volume in 1 min.

Adolphi, Natalie L.; Huber, Dale L.; Jaetao, Jason E.; Bryant, Howard C.; Lovato, Debbie M.; Fegan, Danielle L.; Venturini, Eugene L.; Monson, Todd C.; Tessier, Trace E.; Hathaway, Helen J.; Bergemann, Christian; Larson, Richard S.; Flynn, Edward R.

2009-05-01

401

Characterization of magnetite nanoparticles for SQUID-relaxometry and magnetic needle biopsy  

PubMed Central

Magnetite nanoparticles (Chemicell SiMAG-TCL) were characterized by SQUID-relaxometry, susceptometry, and TEM. The magnetization detected by SQUID-relaxometry was 0.33% of that detected by susceptometry, indicating that the sensitivity of SQUID-relaxometry could be significantly increased through improved control of nanoparticle size. The relaxometry data were analyzed by the moment superposition model (MSM) to determine the distribution of nanoparticle moments. Analysis of the binding of CD34-conjugated nanoparticles to U937 leukemia cells revealed 60,000 nanoparticles per cell, which were collected from whole blood using a prototype magnetic biopsy needle, with a capture efficiency of >65% from a 750 µl sample volume in 1 minute. PMID:20161153

Adolphi, Natalie L.; Huber, Dale L.; Jaetao, Jason E.; Bryant, Howard C.; Lovato, Debbie M.; Fegan, Danielle L.; Venturini, Eugene L.; Monson, Todd C.; Tessier, Trace E.; Hathaway, Helen J.; Bergemann, Christian; Larson, Richard S.; Flynn, Edward R.

2009-01-01

402

Large Scale Production of Magnetic Nanoparticles Using Bacterial Fermentation  

SciTech Connect

Microbial production of nano-sized particles has a demonstrated capacity to make highly crystalline pure phase magnetite or with some substitution of Fe by Co, Ni, Cr, Mn, Zn or the rare earths. Microbial production of magnetic nanopa