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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

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

PubMed

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

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

2014-06-01

6

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

7

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

8

Agglomeration of magnetic nanoparticles.  

PubMed

The formation of agglomerates by salt-induced double layer compression of magnetic nanoparticles in the absence and presence of an external magnetic field was investigated experimentally as well as computationally in this study. The structures of the agglomerates were analyzed through scanning electron microscopy and proved to be highly porous and composed of large spaces among the branches of a convoluted network. In the absence of an external magnetic field, the branches of such a network were observed to be oriented in no particular direction. In contrast, when the agglomeration process was allowed to occur in the presence of an external magnetic field, these branches appeared to be oriented predominantly in one direction. A modified Discrete Element Method was applied to simulate the agglomeration process of magnetic nanoparticles both in the absence and presence of an external magnetic field. The simulations show that agglomeration occurred by the formation of random clusters of nanoparticles which then joined to form a network. In the presence of anisotropic magnetic forces, these clusters were rotated to align along the direction of the magnetic field and the final network formed consisted largely of elongated branches of magnetic nanoparticles. PMID:22462837

Lim, Eldin Wee Chuan; Feng, Ruili

2012-03-28

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 magnetic excitations in nanoparticles  

Microsoft Academic Search

We have used a spin-wave model to calculate the temperature dependence of the (sublattice) magnetization of magnetic nanoparticles. The uniform precession mode, corresponding to a spin wave with wave vector q=0 , is predominant in nanoparticles and gives rise to an approximately linear temperature dependence of the (sublattice) magnetization well below the superparamagnetic blocking temperature for both ferro-, ferri-, and

Steen Mørup; Britt Rosendahl Hansen

2005-01-01

11

Magnetic properties of iron nanoparticle  

SciTech Connect

Magnetic properties of Fe nanoparticles with different sizes synthesized by a physical deposition technique have been investigated experimentally. We have used a high pressure sputtering technique to deposit iron nanoparticles on a silicon substrate. The nanoparticles are then analyzed using atomic force microscopy (AFM), transmission electron microscopy (TEM), and superconducting quantum interference device techniques. TEM and AFM data show that the particle size could be tuned by adjusting the deposition conditions. The magnetic properties have been investigated from temperature dependent magnetization M(T) and field dependent magnetization M(H) measurements. The results show that two phases including both ferromagnetic and superparamagnetic particles are present in our system. From these data we extracted the superparamagnetic critical size to be 9 nm for our samples. Ferromagnetic particles are single magnetic domain particles and the magnetic properties can be explained by the Stoner and Wohlfarth model. For the superparamagnetic phase, the effective anisotropy constant, K{sub eff}, decreases as the particle size increases.

Carvell, J.; Ayieta, E.; Gavrin, A.; Cheng, Ruihua [Department of Physics, Indiana University Purdue University Indianapolis, 402 N Blackford Street Indianapolis, Indiana 46202 (United States); Shah, V. R.; Sokol, P. [Department of Physics, Indiana University, 727 E. Third Street Bloomington, Indiana 47405 (United States)

2010-05-15

12

Functional Magnetic Nanoparticles  

Microsoft Academic Search

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.\\u000aMagnetite nanoparticles

James Gass

2012-01-01

13

Do antibody-coated bacteria prove bacterial prostatitis?  

Microsoft Academic Search

Summary Using the immunofluorescence technique in 187 patients with bacteriologically proven prostatitis according to the Meares-Stamey test demonstrated a significant amount of antibody-coated bacteria (ACB) in their ejaculates. The ACB test was useful to discriminate between chronic bacterial prostatitis and prostatodynia with a sensitivity of 65% and a specifity of 92%; likewise the ACB test is superior to complement and

G. Riedasch; K. Möhring; E. Ritz

1991-01-01

14

SolidPhase Radioimmunoassay in Antibody-Coated Tubes  

Microsoft Academic Search

The adsorption of antibody to polymeric surfaces has been used to develop a new method of solid-phase radioimmunoassay. Incubation is performed in antibody-coated, disposable tubes that are finally washed-out with water and counted for quantitation of the bound tracer. The method is simple, rapid, inexpensive, and suitable for automation.

Kevin Catt; Geoffrey W. Tregear

1967-01-01

15

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

16

Nanoparticles studied by magnetic speckles  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles self assemblies are promising for advanced permanent magnetic applications [1]. The recent development of Soft X-Ray Resonant Magnetic Scattering (SXRMS) provides a very good tool to study magnetic order and reversal processes in such nanostructures. The chemical selectivity and the polarization sensitivity allows to probe the magnetic configuration, as shown by recent studies on superparamagnetic Co particle assemblies [2]. Moreover, by using coherent light and 2D detection one can obtain remarkable speckle patterns that are related to the local magnetic distribution [3,4]. In this work, we present spectroscopy measurments in circular polarization as well as SXRMS measurement performed in transmission geometry (small angle scattering) on Co and Fe3O4 nanoparticles assemblies. We recorded magnetic speckles in linear polarization at specific points tempertaure and magetic field. By studying the cross-correlation between the speckles patterns, we can measure the statistical evolution of the microscopic magnetic distribution through the superparamagnetic transition. [1] H. Zeng et al. Nature 240, 395 (2002) [2] J.B. Kortright et al., Phys. Rev. B 70, (2004) in press. [3] K.Chesnel et al., Phys. Rev. B 66, 172404 (2002) [4] M. S. Pierce et al., Phys. Rev. Lett. 90, 175502 (2003).

Chesnel, Karine; Kevan, Steve; Kortright, Jeffrey; Fullerton, Eric; Sun, Shouheng; Krishnan, Kannan

2005-03-01

17

Interaction of erythrocytes with magnetic nanoparticles.  

PubMed

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

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

2007-03-01

18

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

19

Magnetic nanoparticles for gene and drug delivery  

PubMed Central

Investigations of magnetic micro- and nanoparticles for targeted drug delivery began over 30 years ago. Since that time, major progress has been made in particle design and synthesis techniques, however, very few clinical trials have taken place. Here we review advances in magnetic nanoparticle design, in vitro and animal experiments with magnetic nanoparticle-based drug and gene delivery, and clinical trials of drug targeting. PMID:18686777

McBain, Stuart C; Yiu, Humphrey HP; Dobson, Jon

2008-01-01

20

Iron oxide magnetic nanoparticles: A short review  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles have been enjoying great importance and wide scale applications during the last two decades due to their specific characteristics and applications. Iron oxide magnetic nanoparticles with appropriate surface chemistry have been implied in numerous applications such as biomedicine and cancer therapy, catalysis and in magnetic separation techniques. This review summarizes recent commercial, industrial and bio-engineering applications and brief study of the methods for the preparation of iron oxide magnetic nanoparticles with a control over the size, morphology and the magnetic properties. Some future applications of microwave irradiation for magnetic particle synthesis are also addressed.

Hasany, S. F.; Rehman, A.; Jose, R.; Ahmed, I.

2012-11-01

21

Magnetic relaxation in dipolar magnetic nanoparticle clusters  

NASA Astrophysics Data System (ADS)

Understanding the role of dipolar interactions on thermal relaxation in magnetic nanoparticle (MNP) systems is of fundamental importance in magnetic recording, for optimizing the hysteresis heating contribution in the hyperthermia cancer treatment in biomedicine, or for biological and chemical sensing, for example. In this talk, we discuss our related efforts to quantify the influence of dipolar interactions on thermal relaxation in small clusters of MNPs. Setting up the master equation and solving the associated eigenvalue problem, we identify the observable relaxation time scale spectra for various types of MNP clusters, and demonstrate qualitatively different spectral characteristics depending on the point group of symmetries of the particle arrangement within the cluster -- being solely a dipolar interaction effect. Our findings provide insight into open questions related to magnetic relaxation in bulk MNP systems, and may prove to be also of practical relevance, e.g., for improving robustness of methodologies in biological and chemical sensing.

Hovorka, Ondrej; Barker, Joe; Chantrell, Roy; Friedman, Gary

2013-03-01

22

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

23

Magnetic resonance imaging of glioblastoma using aptamer conjugated magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Here we introduce a new class of smart imaging probes hybridizing polysorbate 80 coated-magnetic nanoparticles with vascular endothelial growth factor receptor 2 (VEGFR2)-targetable aptamer for specific magnetic resonance (MR) imaging of angiogenesis from glioblastoma.

Kim, Bongjune; Yang, Jaemoon; Hwang, Myeonghwan; Suh, Jin-Suck; Huh, Yong-Min; Haam, Seungjoo

2012-10-01

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

Magnetic nanoparticle sensing: decoupling the magnetization from the excitation field  

NASA Astrophysics Data System (ADS)

Remote sensing of magnetic nanoparticles (MNPs) has exciting applications for MNP hyperthermia and molecular detection. We introduce, simulate, and experimentally demonstrate an innovation—a sensing coil that is geometrically decoupled from the excitation field—for MNP 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.

Reeves, Daniel B.; Weaver, John B.

2014-01-01

26

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

27

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

28

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

29

Properties and biomedical applications of magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

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

Regmi, Rajesh Kumar

30

Magnetic-Plasmonic Core-Shell Nanoparticles  

PubMed Central

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

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

2013-01-01

31

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

32

Application of Magnetic Nanoparticles to Gene Delivery  

PubMed Central

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

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

2011-01-01

33

Terahertz magnetic modulator based on magnetically clustered nanoparticles  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

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

Tailored magnetic nanoparticles for optimizing magnetic fluid hyperthermia  

E-print Network

Tailored magnetic nanoparticles for optimizing magnetic fluid hyperthermia Amit P. Khandhar,1 R (wileyonlinelibrary.com). DOI: 10.1002/jbm.a.34011 Abstract: Magnetic Fluid Hyperthermia (MFH) is a promising approach no significant in vitro toxicity. Using a dedicated hyperthermia system, we then identified that 16 nm

Krishnan, Kannan M.

36

Approaches for modeling magnetic nanoparticle dynamics  

PubMed Central

Magnetic nanoparticles are useful biological probes as well as therapeutic agents. There have been several approaches used to model nanoparticle magnetization dynamics for both Brownian as well as Néel rotation. The 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

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...

38

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

PubMed Central

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

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

2013-01-01

39

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

PubMed

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

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

2013-01-01

40

Preparation and characterization of magnetic nanoparticles with chitosan coating  

Microsoft Academic Search

Magnetic chitosan nanoparticles were prepared by the suspension cross-linking technique for use in the application of magnetic carrier technology. The Fe3O4 magnetic nanoparticles were synthesized by co-precipitation of FeCl2 and FeCl3 solution in base medium for using in the preparation of the magnetic chitosan. The morphological and magnetic properties of the magnetic nanoparticles were characterized by different techniques (TEM, XRD,

Doan Thi Kim Dung; Tran Hoang Hai; Le Hong Phuc; Bui Duc Long; Le Khanh Vinh; Phan Nha Truc

2009-01-01

41

Measurement of magnetic nanoparticle relaxation time  

PubMed Central

Purpose: Nanoparticle relaxation time measurements have many applications including characterizing molecular binding, viscosity, heating, and local matrix stiffness. The methods capable of in vivo application are extremely limited. The hypothesis investigated by the authors was that the relaxation time could be measured quantitatively using magnetic spectroscopy of nanoparticle Brownian motion (MSB). Methods: The MSB signal (1) reflects the nanoparticle rotational Brownian motion, (2) can be measured from very low nanoparticle concentrations, and (3) is a function of the product of the drive frequency and the relaxation time characterizing Brownian motion. To estimate the relaxation time, the MSB signal was measured at several frequencies. The MSB signal for nanoparticles with altered relaxation time is a scaled version of that for reference nanoparticles with a known relaxation time. The scaling factor linking the altered and reference MSB measurements is the same factor linking the altered and reference relaxation times. The method was tested using glycerol solutions of varying viscosities to obtain continuously variable relaxation times. Results: The measured relaxation time increased with increasing viscosity of the solution in which the nanoparticles resided. The MSB estimated relaxation time matched the calculated relaxation times based on viscosity with 2% average error. Conclusions: MSB can be used to monitor the nanoparticle relaxation time quantitatively through a scale space correlation of the MSB signal as a function of frequency. PMID:22559648

Weaver, John B.; Kuehlert, Esra

2012-01-01

42

Thermoinduced Magnetization in NiO Nanoparticles  

NASA Astrophysics Data System (ADS)

The low-temperature magnetic susceptibility for model NiO nanoparticles is calculated using the Monte Carlo method, and three different behaviors are seen. With uncompensated spins present, the susceptibility diverges as T->0. For cube- shaped nanoparticles, a temperature-dependent thermoinduced magnetization is observed. For spherical and octahedral nanoparticles, a temperature-independent susceptibility associated with the spin-flop configuration is observed. Calculations for arbitrary values of the uniaxial anisotropy indicate that thermoinduced magnetization can be observed for all geometries in materials with strong enough anisotropy. This work was sponsored by the LDRD program of ORNL, by the DOE-OS through the Offices of BES, Division of MSE and ASCR, MICS Division. The ?--Mag tool set was developed as part of a BES sponsored Computational Material Science Network project. ORNL is managed by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725.

Brown, Gregory

2009-03-01

43

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

44

Preparation and characterization of magnetic nanoparticles with chitosan coating  

NASA Astrophysics Data System (ADS)

Magnetic chitosan nanoparticles were prepared by the suspension cross-linking technique for use in the application of magnetic carrier technology. The Fe3O4 magnetic nanoparticles were synthesized by co-precipitation of FeCl2 and FeCl3 solution in base medium for using in the preparation of the magnetic chitosan. The morphological and magnetic properties of the magnetic nanoparticles were characterized by different techniques (TEM, XRD, VSM, FTIR, etc.). The magnetic properties of chitosan - magnetic nanoparticles were analyzed by VSM, and MS around 15 emu/g.

Dung, Doan Thi Kim; Hoang Hai, Tran; Phuc, Le Hong; Long, Bui Duc; Khanh Vinh, Le; Nha Truc, Phan

2009-09-01

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

Simulations of magnetic nanoparticle Brownian motion  

NASA Astrophysics Data System (ADS)

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

Reeves, Daniel B.; Weaver, John B.

2012-12-01

47

Microfluidic biosensing systems using magnetic nanoparticles.  

PubMed

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

48

Functionalized magnetic nanoparticle analyte sensor  

DOEpatents

A method and system for simply and efficiently determining quantities of a preselected material in a particular solution by the placement of at least one superparamagnetic nanoparticle having a specified functionalized organic material connected thereto into a particular sample solution, wherein preselected analytes attach to the functionalized organic groups, these superparamagnetic nanoparticles are then collected at a collection site and analyzed for the presence of a particular analyte.

Yantasee, Wassana; Warner, Maryin G; Warner, Cynthia L; Addleman, Raymond S; Fryxell, Glen E; Timchalk, Charles; Toloczko, Mychailo B

2014-03-25

49

Multifunctional Magnetic Nanoparticles for Targeted Delivery  

PubMed Central

A major problem associated with therapy is the inability to deliver pharmaceuticals to a specific site of the body without causing nonspecific toxicity. Development of magnetic nanoparticles and techniques for their safe transport and concentration in specific sites in the body would constitute a powerful tool for gene/drug therapy in vivo. Furthermore, drug delivery in vitro could improve further if the drugs were modified with antibodies, proteins or ligands. For in vivo experiments, magnetic nanoparticles were conjugated with plasmid DNA expressing GFP and then coated with chitosan. These particles were injected into mice through tail vein and directed to heart and kidney by means of external magnets of 25 gauss or 2kA –kA/m. These particles were concentrated in the lungs, heart, and kidney of mice and the expression of GFP in these sites were monitored. The expression of GFP in specific locations was visualized by whole-body fluorescent imaging and the concentration of these particles in the designated body locations was confirmed by transmission electron microscopy. In another model system, we used atrial natriuretic peptide (ANP) and Carcino Embryonic Antigen (CEA) antibodies coupled to the chitosan coated magnetic nanoparticles to target cells in vitro. The present work demonstrates that a simple external magnetic field is all that is necessary to target a drug to a specific site inside the body without the need to functionalize the nanoparticles. However, the option to use magnetic targeting with external magnets on functionalized nanoparticles could prove as a more efficient means of drug delivery. PMID:19446653

Kumar, Arun; Jena, Prasanna K.; Behera, Sumita; Lockey, Richard F.; Mohapatra, Subhra; Mohapatra, Shyam

2012-01-01

50

Nanocomposites of magnetic cobalt nanoparticles and cellulose  

NASA Astrophysics Data System (ADS)

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

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

2008-10-01

51

Magnetic nanoparticles for cancer diagnosis and therapy.  

PubMed

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; Medarova, Zdravka

2012-05-01

52

Targeted polymeric magnetic nanoparticles for brain imaging  

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

53

New magnetic nanoparticles for biotechnology  

Microsoft Academic Search

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

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

2004-01-01

54

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

55

Productive encounter: molecularly imprinted nanoparticles prepared using magnetic templates.  

PubMed

Synthesis of core-shell nanoparticles by surface initiated reversible addition fragmentation chain transfer polymerization in presence of a chiral template conjugated to magnetic nanoparticles is reported. The approach leads to imprinted nanoparticles featuring enantioselectivity and enhanced affinity compared to nanoparticles prepared using free template. PMID:24983025

Berghaus, Melanie; Mohammadi, Reza; Sellergren, Börje

2014-08-18

56

Plasmonic-magnetic bifunctional nanoparticles.  

SciTech Connect

An amorphous seed-mediated strategy has been developed for the synthesis of hybrid nanoparticles that are composed of silver (yellow) and iron oxide (blue) nanodomains and exhibit unique optical properties. These properties originate from both the strong surface plasmon resonance of the silver and the strong superparamagnetic responses of the iron oxide nanodomains.

Peng, S.; Lei, C.; Ren, Y.; Cook, R. E.; Sun, Y. (Center for Nanoscale Materials); ( MSD); ( XSD); (Univ. of Illinois)

2011-03-01

57

Gum Arabic surface-modified magnetic nanoparticles for cancer therapy  

Microsoft Academic Search

The objective of this study is to investigate the influence of Gum Arabic-modified magnetic nanoparticles on cellular uptake. The ultimate goal is to develop a technique to promote the selective uptake of magnetic nanoparticles by cancer cells for cancer treatment. A novel use of magnetic fields and magnetic particles is to deliver therapeutic drugs at the desired time in the

U. Effiong; D. Williams; W. Otto; W. Anderson

2004-01-01

58

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

59

Multifunctional magnetic nanoparticles for biomedical applications  

NASA Astrophysics Data System (ADS)

Magnetic iron oxide nanoparticles have intrinsic advantages over other nanoparticles for various biomedical applications. These advantages include visualization, heating, and movement properties. There are now numerous efforts underway to expand the applications of these particles for non-invasive magnetic targeting/localization, drug/adjuvant delivery and release, cellular imaging and cellular therapies. In order to move these applications forward it is necessary to define new assays and methods to visualize, move and heat these particles and define their interactions with cellular systems. Our studies of the movement and heating of these nanoparticles in solutions and gels suggest a strong response of these properties to the size and coating of the particles, the suspending medium and the field parameters. Additionally, cellular association is a strong function of the coating and concentration of the nanoparticles and the time of incubation. X-ray computed tomography (CT) can be used to image at least two orders of concentration (1-40 mg Fe/ml) higher than that by 1.5 T Magnetic Resonance (MR) (0.01-0.4 mg Fe/ml) and could prove to be useful for image-guided treatments in vivo.

Kalambur, Venkat S.; Hui, Susanta; Bischof, John C.

2007-02-01

60

Simultaneous quantification of multiple magnetic nanoparticles  

PubMed Central

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. PMID:20947953

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

2013-01-01

61

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

62

Multi-vortex states in magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

We demonstrate a fabrication technique to create cylindrical NiFe magnetic nanoparticles (MNPs) with controlled dimensions and composition. MNPs thicker than 200 nm can form a double vortex configuration, which consists of a pair of vortices with opposite chirality. When MNPs thicker than 300 nm are relaxed after saturation, it forms a frustrated triple vortex state which produces a higher net magnetization as verified by light transmissivity measurements. Therefore, a greater magnetic torque can be actuated on a MNP in the triple vortex state.

Gan, W. L.; Chandra Sekhar, M.; Wong, D. W.; Purnama, I.; Chiam, S. Y.; Wong, L. M.; Lew, W. S.

2014-10-01

63

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

64

Nonlinear simulations to optimize magnetic nanoparticle hyperthermia  

SciTech Connect

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., E-mail: dbr@Dartmouth.edu; Weaver, John B. [Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States)

2014-03-10

65

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

66

Magnetic and electromagnetic evaluation of the magnetic nanoparticle filled polyurethane nanocomposites  

E-print Network

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

Guo, John Zhanhu

67

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

68

The effect of static magnetic fields on the aggregation and cytotoxicity of magnetic nanoparticles  

Microsoft Academic Search

Biomedical applications of magnetic nanoparticles (MNP), including superparamagnetic nanoparticles, have expanded dramatically in recent years. Systematic and standardized cytotoxicity assessment to ensure the biosafety and biocompatibility of those applications is compulsory. We investigated whether exposure to static magnetic field (SMF) from e.g. magnetic resonance imaging (MRI) could affect the cytotoxicity of superparamagnetic iron oxide (SPIO) nanoparticles using mouse hepatocytes and

Ji-Eun Bae; Man-Il Huh; Byung-Kyu Ryu; Ji-Yeon Do; Seong-Uk Jin; Myung-Jin Moon; Jae-Chang Jung; Yongmin Chang; Eungseok Kim; Sung-Gil Chi; Gang-Ho Lee; Kwon-Seok Chae

2011-01-01

69

Sensitivity of dipole magnetic tomography to magnetic nanoparticle injectates  

NASA Astrophysics Data System (ADS)

We compare the sensitivity of magnetic field measurements to perturbations of magnetic permeability with the field sensitivity to conductivity alterations. The conductivity perturbations can be caused by the different conductivity of the injected and formation resident fluid and the magnetic permeability perturbations by injecting magnetic nanoparticles. We devise a simple method for calculating the magnetic permeability sensitivity required to solve parametric inverse problems in electromagnetic (EM) tomography involving magnetic permeability perturbations. We apply the method in 3D and 2D axisymmetric to both crosswell and single-well configurations in a homogeneous background. The emphasis of this paper is on measurements acquired at very low induction numbers (kr ? 1; k being the wave number and r the distance) where the wave length or the skin depth becomes an irrelevant scale.

Rahmani, Amir Reza; Athey, Alex E.; Chen, Jiuping; Wilt, Michael J.

2014-04-01

70

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

71

The Effects of Magnetic Nanoparticles on Magnetic Fluid Hyperthermia  

NASA Astrophysics Data System (ADS)

Magnetic fluid hyperthermia (MFH) is a cancer treatment in which biocompatible magnetic nanoparticles are dispersed into a tumor and heated by an external AC magnetic field. Over a period of time, the tumor cells are locally heated, leading to hyperthermia which damages and kills the tumor cells with minimal damage to the surrounding normal tissue. The applied magnetic field must be high enough to induce hyperthermia for a specified magnetic particle concentration in the tumor but also lies within the safe limit for human exposure. Six materials, barium ferrite, cobalt ferrite, iron-cobalt, iron-platinum, magnetite and maghemite, are considered as candidates for MFH use. We find that fcc iron-platinum, magnetite and maghemite generate useful treatment temperatures and, when included in a ferrofluid, can produce sufficient and effective MFH for which optimal conditions are explored.

Liangruksa, Monrudee; Kappiyoor, Ravi; Ganguly, Ranjan; Puri, Ishwar

2010-11-01

72

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

73

Preparation and Properties of Various Magnetic Nanoparticles  

PubMed Central

The fabrications of iron oxides nanoparticles using co-precipitation and gadolinium nanoparticles using water in oil microemulsion method are reported in this paper. Results of detailed phase analysis by XRD and Mössbauer spectroscopy are discussed. XRD analysis revealed that the crystallite size (mean coherence length) of iron oxides (mainly ?-Fe2O3) in the Fe2O3 sample was 30 nm, while in Fe2O3/SiO2 where the ?-Fe2O3 phase dominated it was only 14 nm. Gd/SiO2 nanoparticles were found to be completely amorphous, according to XRD. The samples showed various shapes of hysteresis loops and different coercivities. Differences in the saturation magnetization (MS) correspond to the chemical and phase composition of the sample materials. However, we observed that MS was not reached in the case of Fe2O3/SiO2, while for Gd/SiO2 sample the MS value was extremely low. Therefore we conclude that only unmodified Fe2O3 nanoparticles are suitable for intended biosensing application in vitro (e.g. detection of viral nucleic acids) and the phase purification of this sample for this purpose is not necessary. PMID:22574017

Drbohlavova, Jana; Hrdy, Radim; Adam, Vojtech; Kizek, Rene; Schneeweiss, Oldrich; Hubalek, Jaromir

2009-01-01

74

Magnoelastic coupling in magnetic oxide nanoparticles  

NASA Astrophysics Data System (ADS)

Phonons are exquisitely sensitive to finite length scale effects in a wide variety of materials. To investigate confinement in combination with strong magnetoelastic interactions, we measured the infrared vibrational properties of MnO and CoFe2O4 nanoparticles and their parent compounds. For MnO, a charge and bonding analysis reveals that Born effective charge, local effective charge, total polarizability, and the force constant are overall lower in the nanoparticles compared to the bulk. We find that the spin-lattice coupling drops from ˜7 cm-1 in the single crystal to <1 cm-1 in the nanoparticles. For CoFe2O4, the spectroscopic response is sensitive to the size-induced crossover to the superparamagnetic state, which occurs between 7 and 10 nm, and a spin-phonon coupling analysis supports the core-shell model. Moreover, it provides an estimate of the thickness of the magnetically disordered shell, increasing from 0.4 nm in the 14 nm particles to 0.8 nm in the 5 nm particles, demonstrating that the associated local lattice distortions take place on the length scale of the unit cell. These findings are important for understanding finite length scale effects in magnetic oxides and other more complex functional oxides.

Sun, Qi; Baker, Sheila; Birkel, Christina; Seshadri, Ram; Tremel, Wolfgang; Christianson, Andrew; Musfeldt, Janice

2012-02-01

75

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.

76

Improving the magnetic resonance imaging contrast and detection methods with engineered magnetic nanoparticles.  

PubMed

Engineering and functionalizing magnetic nanoparticles have been an area of the extensive research and development in the biomedical and nanomedicine fields. Because their biocompatibility and toxicity are well investigated and better understood, magnetic nanoparticles, especially iron oxide nanoparticles, are better suited materials as contrast agents for magnetic resonance imaging (MRI) and for image-directed delivery of therapeutics. Given tunable magnetic properties and various surface chemistries from the coating materials, most applications of engineered magnetic nanoparticles take advantages of their superb MRI contrast enhancing capability as well as surface functionalities. It has been found that MRI contrast enhancement by magnetic nanoparticles is highly dependent on the composition, size and surface properties as well as the degree of aggregation of the nanoparticles. Therefore, understanding the relationships between these intrinsic parameters and the relaxivities that contribute to MRI contrast can lead to establishing essential guidance that may direct the design of engineered magnetic nanoparticles for theranostics applications. On the other hand, new contrast mechanism and imaging strategy can be developed based on the novel properties of engineered magnetic nanoparticles. This review will focus on discussing the recent findings on some chemical and physical properties of engineered magnetic nanoparticles affecting the relaxivities as well as the impact on MRI contrast. Furthermore, MRI methods for imaging magnetic nanoparticles including several newly developed MRI approaches aiming at improving the detection and quantification of the engineered magnetic nanoparticles are described. PMID:22272222

Huang, Jing; Zhong, Xiaodong; Wang, Liya; Yang, Lily; Mao, Hui

2012-01-01

77

Preparation of magnetic chitosan nanoparticles and immobilization of laccase  

Microsoft Academic Search

The magnetic chitosan nanoparticles were prepared by reversed-phase suspension method using Span-80 as an emulsifier, glutaraldehyde\\u000a as cross-linking reagent. And the nanoparticles were characterized by TEM, FT-IR and hysteresis loop. The results show that\\u000a the nanoparticles are spherical and almost superparamagnetic. The laccase was immobilized on nanoparticles by adsorption and\\u000a subsequently by cross-linking with glutaraldehyde. The immobilization conditions and characterizations

Hua Fang; Jun Huang; Liyun Ding; Mingtian Li; Zhao Chen

2009-01-01

78

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

79

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

80

Conjugation of catecholamines on magnetic nanoparticles coated with sulfonated chitosan  

Microsoft Academic Search

We synthesized a novel magnetic nanoparticle coated with sulfonated complex (HSO3-CS-DMSA) of meso-2, 3-dimercaptosuccinic acid (DMSA) and chitosan (CS) to improve conjugation of catecholamines (CAs) on nanoparticles. HSO3-CS-DMSA@MNPs exhibited the highest CAs’ conjugation efficiency among three types of magnetic nanoparticles. CAs’ conjugation efficiency was increased in order of MNPs, DMSA@MNPs and HSO3-CS-DMSA@MNPs. CAs’ conjugation efficiency at pH 7 depended on

Ting Qiao; Yihang Wu; Jing Jin; Wei Gao; Qiaozhen Xie; Shuang Wang; Yu Zhang; Huihua Deng

2011-01-01

81

Bleomycin Loaded Magnetic Chitosan Nanoparticles as Multifunctional Nanocarriers  

Microsoft Academic Search

Iron oxide (Fe3O4) containing magnetic chitosan nanoparticles were prepared with Concanavalin-A and Bleomycin as multifunctional nanocarriers for the targeted cancer therapy by co-precipitation techniques. The chemical structures of nanoparticles were analyzed by FTIR and the magnetic properties of the nanoparticles were evaluated by electron spin resonance technique and vibrational scanning mangnetometer measurements. The in vitro release profiles of Bleomycin were

Do?a Kavaz; Sedat Odaba?; Eylem Güven; Murat Demirbilek; Emir Baki Denkba?

2010-01-01

82

Progress in applications of magnetic nanoparticles in biomedicine  

Microsoft Academic Search

In 2003 Journal of Physics D: Applied Physics published three sequential review articles on the subject of biomedical applications of magnetic nanoparticles. At that time there was growing interest in basic research on the potential of magnetic nanoparticles in biomedicine, including the appropriate methods to synthesize the particles and how to functionalize them. Following that initial publication the field has

Kevin OGrady

2009-01-01

83

Kinetics and pathogenesis of intracellular magnetic nanoparticle cytotoxicity  

Microsoft Academic Search

Magnetic nanoparticles excited by alternating magnetic fields (AMF) have demonstrated effective tumor-specific hyperthermia. This treatment is effective as a monotherapy as well as a therapeutic adjuvant to chemotherapy and radiation. Iron oxide nanoparticles have been shown, so far, to be non-toxic, as are the exciting AMF fields when used at moderate levels. Although higher levels of AMF can be more

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

2011-01-01

84

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

85

EDITORIAL: Progress in applications of magnetic nanoparticles in biomedicine Progress in applications of magnetic nanoparticles in biomedicine  

Microsoft Academic Search

In 2003 Journal of Physics D: Applied Physics published three sequential review articles on the subject of biomedical applications of magnetic nanoparticles. At that time there was growing interest in basic research on the potential of magnetic nanoparticles in biomedicine, including the appropriate methods to synthesize the particles and how to functionalize them. Following that initial publication the field has

Kevin O'Grady

2009-01-01

86

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

87

Magnetization Reversal in Transition Metal Doped ZnO Nanoparticles  

NASA Astrophysics Data System (ADS)

We report magnetic properties of transition metal (TM) doped ZnO nanoparticles and compare the doping effects of different transition metal ions into the ZnO matrix. Stoner-Wohlfarth model has been used to study the switching behavior of magnetic moments by observing energy diagram and hysteresis. Low magnetic anisotropy in Zn1-xMxO nanoparticles is observed where M=Fe, Co, Ni and x is the dopant amount. We have considered chemical precipitation technique for the preparation of Zn1-xMxO samples and have compared the reversal processes of magnetic moments with respect to time in the nanoparticles.

Mondal, Trisha; Tripathi, Ajay; Tiwari, Archana

88

A feasibility study of magnetic separation of magnetic nanoparticle for forward osmosis.  

PubMed

It was recently reported that a UK company has developed a naturally non-toxic magnetoferritin to act as a draw solute for drawing water in forward osmosis process. The gist of this technology is the utilization of the magnetic nanoparticle and high-gradient magnetic separation for draw solute separation and reuse. However, any demonstration on this technology has not been reported yet. In this study, a feasibility test of magnetic separation using magnetic nanoparticle was therefore performed to investigate the possibility of magnetic separation in water treatment such as desalination. Basically, a magnetic separation system consisted of a column packed with a bed of magnetically susceptible wools placed between the poles of electromagnet and Fe3O4 magnetic nanoparticle was used as a model nanoparticle. The effect of nanoparticle size to applied magnetic field in separation column was experimentally investigated and the magnetic field distribution in a magnet gap and the magnetic field gradient around stainless steel wool wire were analyzed through numerical simulation. The amount of magnetic nanoparticle captured in the separator column increased as the magnetic field strength and particle size increased. As a result, if magnetic separation is intended to be used for draw solute separation and reuse, both novel nanoparticle and large-scale high performance magnetic separator must be developed. PMID:22097022

Kim, Y C; Han, S; Hong, S

2011-01-01

89

Tailored magnetic nanoparticles for in vitro, in vivo and in situ magnetorelaxometry  

E-print Network

the acute cytotoxicity of magnetic nanoparticles and theirCytotoxicity of colloidal CdSe and CdSe/ZnS nanoparticles."cytotoxicity and the effect that the delivery of synthesized anionic magnetic nanoparticles

Pisanic, Thomas R.

2006-01-01

90

Size control of magnetic carbon nanoparticles for drug delivery.  

PubMed

Carbonized polypyrrole nanoparticles with controlled diameters were readily fabricated by the pyrolysis of polypyrrole nanoparticles. The carbonized polypyrrole nanoparticles showed narrow size distribution, large micropore volume, and high surface area. Magnetic phases were introduced into the carbon nanoparticles during the pyrolysis without sophisticated process, which resulted in useful magnetic properties for selective nanoparticle separation. Field emission scanning electron microscopy, Raman spectrometer, N(2) adsorption/desorption, X-ray diffraction, and superconducting interference device were employed for characterizing the carbonized polypyrrole nanoparticles. Hydrophobic guest molecules were incorporated into the carbonized polypyrrole nanoparticles by surface adsorption, pore filling, and surface covalent coupling. The carbonized polypyrrole nanoparticles exhibited embedding capability using pyrene as a typical hydrophobic fluorescent molecule. In addition, ibuprofen was incorporated into the carbon nanoparticles, and drug-loaded carbon nanoparticles sustained release property. In addition, the carbonized polypyrrole nanoparticles revealed low toxicity at concentrations below 100 microg mL(-1) via cell viability test and were uptaken inside the cells. These results suggest a new platform for the drug delivery using carbonized polypyrrole nanoparticles. PMID:19878989

Oh, W-K; Yoon, H; Jang, J

2010-02-01

91

A renewable electrochemical magnetic immunosensor based on gold nanoparticle labels.  

PubMed

A particle-based renewable electrochemical magnetic immunosensor was developed by using magnetic beads and gold nanoparticle labels. Anti-IgG antibody-modified magnetic beads were attached to a renewable carbon paste transducer surface by magnet that was fixed inside the sensor. Gold nanoparticle labels were capsulated to the surface of magnetic beads by sandwich immunoassay. Highly sensitive electrochemical stripping analysis offers a simple and fast method to quantify the capatured gold nanoparticle tracers and avoid the use of an enzyme label and substrate. The stripping signal of gold nanoparticles is related to the concentration of target IgG in the sample solution. A transmission electron microscopy image shows that the gold nanoparticles were successfully capsulated to the surface of magnetic beads through sandwich immunoreaction events. The parameters of immunoassay, including the loading of magnetic beads, the amount of gold nanoparticle conjugate, and the immunoreaction time, were optimized. The detection limit of 0.02 microg ml(-1) of IgG was obtained under optimum experimental conditions. Such particle-based electrochemical magnetic immunosensors could be readily used for simultaneous parallel detection of multiple proteins by using multiple inorganic metal nanoparticle tracers and are expected to open new opportunities for disease diagnostics and biosecurity. PMID:16108428

Liu, Guodong; Lin, Yuehe

2005-07-01

92

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

2014-09-01

93

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

94

Adsorption of bovin serum albumin (BSA) onto the magnetic chitosan nanoparticles prepared by a microemulsion system  

Microsoft Academic Search

The adsorption characteristics of BSA onto the magnetic chitosan nanoparticles have been investigated in this paper. The magnetic chitosan nanoparticles were prepared by adding the basic precipitant of NaOH solution into a W\\/O microemulsion system. The morphology of magnetic chitosan nanoparticles was observed by transmission electron microscope (TEM). It was found that the diameter of magnetic chitosan nanoparticles was from

Yujun Wang; Xianghua Wang; Guangsheng Luo; Youyuan Dai

2008-01-01

95

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 Available online 19 September 2011 Keywords: Magnetic nanoparticle Targeted drug deliver Magnetic drug targeting Optimal permanent magnet Nano-particle trapping Pushing nanoparticle Halbach array design a b

Shapiro, Benjamin

96

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

97

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

98

Development of magnetic chromatography to sort polydisperse nanoparticles in ferrofluids.  

PubMed

Whatever the strategy of synthesis, nanoparticles in magnetic fluids commonly feature a broad size distribution. However, the presence of several size populations in ferrofluids is often problematic because of the close relationship between the efficiency of the nanoparticles and their physicochemical properties. In this work, a magnetic size sorting procedure is developed in order to reduce this polydispersity, using the magnetic properties of the iron oxide nanoparticles. This magnetic sorting with an adjustable magnetic field allows isolation of the small superparamagnetic particles as well as the larger particles. Magnetometry, nuclear magnetic relaxation dispersion profiles and transmission electron microscopy were successfully used to check the efficiency of the magnetic sorting procedure, which was shown to work as a 'magnetic' chromatography. PMID:20586034

Forge, Delphine; Gossuin, Yves; Roch, Alain; Laurent, Sophie; Elst, Luce Vander; Muller, Robert N

2010-01-01

99

Differential magnetic catch and release: Separation, purification, and characterization of magnetic nanoparticles and particle assemblies  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles uniquely combine superparamagnetic behavior with dimensions that are smaller than or the same size as molecular analytes. The integration of magnetic nanoparticles with analytical methods has opened new avenues for sensing, purification, and quantitative analysis. Applied magnetic fields can be used to control the motion and properties of magnetic nanoparticles; in analytical chemistry, use of magnetic fields provides methods for manipulating and analyzing species at the molecular level. The ability to use applied magnetic fields to control the motion and properties of magnetic nanoparticles is a tool for manipulating and analyzing species at the molecular level, and has led to applications including analyte handing, chemical sensors, and imaging techniques. This is clearly an area where significant growth and impact in separation science and analysis is expected in the future. In Chapter 1, we describe applications of magnetic nanoparticles to analyte handling, chemical sensors, and imaging techniques. Chapter 2 reports the purification and separation of magnetic nanoparticle mixtures using the technique developed in our lab called differential magnetic catch and release (DMCR). This method applies a variable magnetic flux orthogonal to the flow direction in an open tubular capillary to trap and controllably release magnetic nanoparticles. Magnetic moments of 8, 12, and 17 nm diameter CoFe2O4 nanoparticles are calculated using the applied magnetic flux density and experimentally determined force required to trap 50% of the particle sample. Balancing the relative strengths of the drag and magnetic forces enable separation and purification of magnetic CoFe2 O4 nanoparticle samples with < 20 nm diameters. Samples were characterized by transmission electron microscopy to determine the average size and size dispersity of the sample population. DMCR is further demonstrated to be useful for separation of a magnetic nanoparticle mixture, resulting in samples with narrowed size distributions. Differential magnetic catch and release has been used as a method for the purification and separation of magnetic nanoparticles. In Chapter 3 the separation metrics are reported. DMCR separates nanoparticles in the mobile phase by magnetic trapping of magnetic nanoparticles against the wall of an open tubular capillary wrapped between two narrowly spaced electromagnetic poles. Using Au and CoFe2O4 nanoparticles as model systems, the loading capacity of the 250 microm diameter capillary is determined to be ˜130 microg, and is scalable to higher quantities with larger bore capillary. Peak resolution in DMCR is externally controlled by selection of the release time (Rt) at which the magnetic flux density is removed, however longer capture times are shown to reduce the capture yield. In addition, the magnetic nanoparticle capture yields are observed to depend on the nanoparticle diameter, mobile phase viscosity and velocity, and applied magnetic flux. Using these optimized parameters, three samples of CoFe 2O4 nanoparticles whose diameters are different by less than 10 nm are separated with excellent resolution and capture yield, demonstrating the capability of DMCR for separation and purification of magnetic nanoparticles. Individual hybrid nanocrystals possess multiple structural units with solid state interfaces, giving them a wide range of possible applications. Synthesis of truly monodisperse nanoparticles and hybrid nanocrystals is a formidable task, which has led us to apply our analytical technique, differential magnetic catch and release, to separate and purify magnetic nanoparticles. Using an open tubular capillary column and electromagnet, DMCR separates magnetic nanoparticles based on a balance of their magnetic moment and hydrodynamic size. Chapter 4 focuses on the purification of real world samples of hybrid nanocrystals including Au-Fe3O4 heterostructures and FePt-Fe3O4 dimers. Samples are characterized with transmission electron microscopy, UV-Vis, X-ray diffraction spectroscopy, selected area electro

Beveridge, Jacob S.

100

Experimental and theoretical investigation of intratumoral nanoparticle distribution to enhance magnetic nanoparticle hyperthermia  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles have gained prominence in recent years for use in clinical applications such as imaging, drug delivery, and hyperthermia. Magnetic nanoparticle hyperthermia is a minimally invasive and effective approach for confined heating in tumors with little collateral damage. One of the major problems in the field of magnetic nanoparticle hyperthermia is irregular heat distribution in tumors which caused repeatable heat distribution quite impossible. This causes under dosage in tumor area and overheating in normal tissue. In this study, we develop a unified approach to understand magnetic nanoparticle distribution and temperature elevations in gel and tumors. A microCT imaging system is first used to visualize and quantify nanoparticle distribution in both tumors and tissue equivalent phantom gels. The microCT based nanoparticle concentration is related to specific absorption rate (SAR) of the nanoparticles and is confirmed by heat distribution experiments in tissue equivalent phantom gels. An optimal infusion protocol is identified to generate controllable and repeatable nanoparticle distribution in tumors. In vivo animal experiments are performed to measure intratumoral temperature elevations in PC3 xenograft tumors implanted in mice during magnetic nanoparticle hyperthermia. The effect of nanofluid injection parameters on the resulted temperature distribution is studied. It shows that the tumor temperatures can be elevated above 50°C using very small amounts of ferrofluid with a relatively low magnetic field. Slower ferrofluid infusion rates result in smaller nanoparticle distribution volumes in the tumors, however, it gives the much required controllability and repeatability when compared to the higher infusion rates. More nanoparticles occupy a smaller volume in the vicinity of the injection site with slower infusion rates, causing higher temperature elevations in the tumors. Based on the microCT imaging analyses of nanoparticles in tumors, a mass transport model is developed to simulate nanoparticle convection and diffusion in tumors, heat-induced tumor structural changes, as well as nanoparticle re-distribution during nanoparticle hyperthermia procedures. The modeled thermal damage induced nanoparticle redistribution predicts a 20% increase in the radius of the spherical tissue region containing nanoparticles. The developed model has demonstrated the feasibility of enhancing nanoparticle dispersion from injection sites using targeted thermal damage.

Attaluri, Anilchandra

101

Proteins and Patients — Magnetic Nanoparticles as Analytic Markers  

NASA Astrophysics Data System (ADS)

Exciting new applications of low noise magnetic sensors in biotechnology, medical diagnosis and therapy are at hand for magnetic nanoparticles (MNP), which are already used in the clinical routine. The relaxation of magnetic nanoparticles is a fascinating method which can be employed for the characterization of ferrofluids and is further developed as analytical tool for biochemistry. In this article the basics and methods of the characterization of diluted ferrofluids by magnetore-laxometry (MRX) are described. We start with the properties of the ferrofluid which consists of magnetic nanoparticles. The time schedule for relaxation measurements is discussed. The details of our fluxgate based experimental set-up are presented. To achieve high sensitivity even at low concentrations of magnetic nanoparticles we optimize fluxgate sensors for low intrinsic noise, high sensitivity and large bandwidth.

Schilling, Meinhard; Ludwig, Frank

102

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

103

Hyperthermic effects of dissipative structures of magnetic nanoparticles in large alternating magnetic fields  

PubMed Central

Targeted hyperthermia treatment using magnetic nanoparticles is a promising cancer therapy. However, the mechanisms of heat dissipation in the large alternating magnetic field used during such treatment have not been clarified. In this study, we numerically compared the magnetic loss in rotatable nanoparticles in aqueous media with that of non-rotatable nanoparticles anchored to localised structures. In the former, the relaxation loss in superparamagnetic nanoparticles has a secondary maximum because of slow rotation of the magnetic easy axis of each nanoparticle in the large field in addition to the known primary maximum caused by rapid Néel relaxation. Irradiation of rotatable ferromagnetic nanoparticles with a high-frequency axial field generates structures oriented in a longitudinal or planar direction irrespective of the free energy. Consequently, these dissipative structures significantly affect the conditions for maximum hysteresis loss. These findings shed new light on the design of targeted magnetic hyperthermia treatments. PMID:22355672

Mamiya, Hiroaki; Jeyadevan, Balachandran

2011-01-01

104

Magnetic nanocomposites: Preparation and characterization of Co-ferrite nanoparticles  

Microsoft Academic Search

Cobalt ferrite nanoparticles, CoFe2O4, are one of the important spinel ferrites because of their high cubic magnetocrystalline anisotropy, high coercivity and moderate saturation magnetization. CoFe2O4 nanoparticles have been known to be a photomagnetic material which shows an interesting light induced coercivity change. In this study, various preparation techniques were used to produce cobalt ferrite nanoparticles: (i) ball milling of a

M. H. Khedr; A. A. Omar; S. A. Abdel-Moaty

105

Magnetic nanocomposites: Preparation and characterization of Co-ferrite nanoparticles  

Microsoft Academic Search

Cobalt ferrite nanoparticles, CoFe2O4, are one of the important spinel ferrites due to their high cubic magnetocrystalline anisotropy, high coercivity and moderate saturation magnetization. CoFe2O4 nanoparticles have been known to be a photomagnetic material which shows an interesting light induced coercivity change. In this study, various preparation techniques were used to produce cobalt ferrite nanoparticles namely, (i) ball milling of

M. H. Khedr; A. A. Omar; S. A. Abdel-Moaty

2006-01-01

106

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

107

Preparation of Magnetic Chitosan Nanoparticles for Diverse Biomedical Applications  

NASA Astrophysics Data System (ADS)

Polymeric nanoparticles with magnetic properties can be potentially used in many fields such as biotechnology, separation processes, optoelectronic, catalysts and/or sensors, medical diagnosis and therapy. In this respect, biopolymers give promising trends due to their excellent biocompatibility and biodegradability. Therefore in this study, magnetic chitosan/Fe3O4 nanoparticles were prepared according to the procedure based on the ionic gelation of chitosan with tripolyphosphate anions. The formation of the particles was a result of the interaction between the negatively charged groups of the tripolyphosphate and the positively charged amino groups of chitosan. The prepared samples were observed by atomic force microscopy to obtain information about the morphology. The mean particle size of the nanoparticles was determined by dynamic light scattering measurements. Nanoparticles were spherical in shape with a particle size range of about 250-400 nm according to obtained data. Magnetic properties of the nanoparticles were determined by using ESR and VSM.

Kavaz, D.; Çirak, T.; Öztürk, E.; Bayram, C.; Denkba?, E. B.

108

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

109

Electrospun Polyacrylonitrile Nanocomposite Fibers Reinforced with Magnetic Nanoparticles  

E-print Network

Electrospun Polyacrylonitrile Nanocomposite Fibers Reinforced with Magnetic Nanoparticles Di Zhang1/Fe3O4 nanocomposite fibers is explored by an electrospinning process. The nanocomposite fibers nanocomposite fibers are different from those of the dried as-received nanoparticles. INTRODUCTION Polymer

Guo, John Zhanhu

110

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

111

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

112

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

113

Immobilization of bovine catalase onto magnetic nanoparticles.  

PubMed

The scope of this study is to achieve carrier-bound immobilization of catalase onto magnetic particles (Fe?O? and Fe?O?NiO? · H?O) to specify the optimum conditions of immobilization. Removal of H2O2 and the properties of immobilized sets were also investigated. To that end, adsorption and then cross-linking methods onto magnetic particles were performed. The optimum immobilization conditions were found for catalase: immobilization time (15 min for Fe?O?; 10 min for Fe2O?NiO? · H?O), the initial enzyme concentration (1 mg/mL), amount of magnetic particles (25 mg), and glutaraldehyde concentration (3%). The activity reaction conditions (optimum temperature, optimum pH, pH stability, thermal stability, operational stability, and reusability) were characterized. Also kinetic parameters were calculated by Lineweaver-Burk plots. The optimum pH values were found to be 7.0, 7.0, and 8.0 for free enzyme, Fe?O?-immobilized catalases, and Fe?O?NiO? · H?O-immobilized catalases, respectively. All immobilized catalase systems displayed the optimum temperature between 25 and 35°C. Reusability studies showed that Fe?O?-immobilized catalase can be used 11 times with 50% loss in original activity, while Fe2O?NiO? · H?O-immobilized catalase lost 67% of activity after the same number of uses. Furthermore, immobilized catalase systems exhibited improved thermal and pH stability. The results transparently indicate that it is possible to have binding between enzyme and magnetic nanoparticles. PMID:23876136

Do?aç, Yasemin ?spirli; Teke, Mustafa

2013-01-01

114

Magnetic Nanoparticles for Multi-Imaging and Drug Delivery  

PubMed Central

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

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

2013-01-01

115

Preparation of Magnetic Chitosan Nanoparticles for Diverse Biomedical Applications  

Microsoft Academic Search

Polymeric nanoparticles with magnetic properties can be potentially used in many fields such as biotechnology, separation\\u000a processes, optoelectronic, catalysts and\\/or sensors, medical diagnosis and therapy. In this respect, biopolymers give promising\\u000a trends due to their excellent biocompatibility and biodegradability. Therefore in this study, magnetic chitosan\\/Fe3O4 nanoparticles were prepared according to the procedure based on the ionic gelation of chitosan with

D. Kavaz; T. Çirak; E. Öztürk; C. Bayram; E. B. Denkba?

2008-01-01

116

Carbon encapsulated magnetic nanoparticles for biomedical applications: thermal stability studies.  

PubMed

Carbon encapsulated magnetic nanoparticles may find many prospective biomedical applications, e.g., in drug and gene delivery systems, disease detection, cancer therapy, rapid toxic cleaning, biochemical sensing, and magnetic resonance imaging. Each of these applications hinges on the relationship between magnetic fields and biological systems. Herein we present the results on the thermal stability of carbon encapsulated magnetic nanoparticles. The products were synthesized by using induction radio frequency (RF) thermal plasma. Phase composition and morphology were studied by powder X-ray diffraction and HRTEM, respectively. Thermal stability was investigated by thermogravimetry and differential thermal analyses. Carbon nanostructures were thermally stable up to 500 K. PMID:17855165

Bystrzejewski, Micha?; Cudzi?o, Stanis?aw; Huczko, Andrzej; Lange, Hubert; Soucy, Gervais; Cota-Sanchez, German; Kaszuwara, Waldemar

2007-11-01

117

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

118

Optical properties of magnetic-plasmonic nanoparticle multilayers  

NASA Astrophysics Data System (ADS)

Magnetic-plasmonic materials are an interesting class of materials for both fundamental and applied research. Knowledge of the optical properties and their origin in the materials is a must. Using a layer-by-layer method, we fabricated magnetic-plasmonic nanoparticle multilayers and measured their optical properties. Discrete dipole approximation calculations to model the optical properties of such materials allow us to understand the observed optical features. Comparing experimental and theoretical results provides us with a detailed insight in the build-up of the nanoparticle multilayers and shows that nanoparticles of the added layers fill holes in previous layers and improve the quality of the sample.

Brullot, Ward; Verbiest, Thierry

2014-09-01

119

Superparamagnetic iron oxide nanoparticles Proton Nuclear Magnetic Resonance Dispersion curves  

NASA Astrophysics Data System (ADS)

Superparamagnetic nanoparticles are widely used as contrast agents for magnetic resonance imaging. We present the Proton Nuclear Magnetic Resonance Dispersion curves for colloidal suspension of iron oxide nanoparticles used as contrast agents. The systems studied are composed of iron oxide nanoparticles of two different sizes, 80 150nm dextran coated and 300 400nm silicon coated. Previous studies show that the longitudinal relaxation time dispersion as a function of the proton Larmor frequency is not easily obtained for the aqueous colloidal suspension of 300 400nm diameter nanoparticles. We obtained this system longitudinal relaxation time dispersion over a broad range of magnetic fields in a viscous medium. A theoretical model that accounts for the relaxation rate of water protons under the influence of such colloidal superparamagnetic nanoparticles was fitted to the experimental data of both systems. The fit allows access to characteristic parameters of superparamagnetic nanoparticles such as the Néel relaxation time, the nanoparticle radius, particle's magnetic moment and translational correlation time, important parameters for the contrast agent efficiency.

Taborda, A.; Carvalho, A.

2008-08-01

120

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

121

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

122

Spatiotemporal control of microtubule nucleation and assembly using magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

123

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

124

Magnetic nanoparticles for medical applications: Progress and challenges  

NASA Astrophysics Data System (ADS)

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 ZnxCo1-xFe2O4 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.; Hempelmann, R.; Caltun, O. F.

2013-11-01

125

Applications of Magnetic Micro- and Nanoparticles in Biology and Medicine  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles were first proposed for biomedical applications in the 1970s - primarily as targeted drug delivery vehicles and MRI contrast agents. Since that time, such particles have found application in a variety of biomedical techniques. In addition to drug delivery, magnetic nanoparticles are now used routinely as MRI contrast agents as well as for magneto-immunoassay and cell sorting. More recently, magnetic micro- and nanoparticles have been used to investigate and manipulate cellular processes both in vitro and in vivo. In addition, biogenic magnetic nanoparticles are also produced in the human body. The iron storage protein, ferritin, consists of a superparamagnetic ferrihydrite core and biogenic magnetite (a ferrimagnet) has also been found in the brain and other organs. Though the role of ferritin and several other magnetic iron oxides in the body is well understood, the origin and role of biogenic magnetite is only now coming to light - and this may have profound implications for our understanding of neurodegenerative diseases, such as Alzheimer's, Parkinson's and Huntington's diseases. This talk will review applications related to magnetic particle-mediated activation of cellular processes for tissue engineering applications and novel methods of magnetofection which have the potential to provide enhanced transfection for non-viral therapeutic gene delivery. It will also briefly highlight new techniques recently developed for the mapping and characterization of magnetic iron compounds related to neurodegenerative diseases and how rock magnetic techniques have been adapted to study magnetic iron compounds in the brain and other organs.

Dobson, J.

2005-12-01

126

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

127

Experimental observations and nucleation and growth theory of polyhedral magnetic ferrite nanoparticles synthesized  

E-print Network

Experimental observations and nucleation and growth theory of polyhedral magnetic ferrite the morphologies of ferrite nanoparticles synthesized using a radio frequency plasma torch. These nanoparticles. Keywords: Ferrite nanoparticles; High-resolution TEM; Polyhedral morphologies; Faceting; Critical nucleus

McHenry, Michael E.

128

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

129

Thermoseeds for interstitial magnetic hyperthermia: from bioceramics to nanoparticles.  

PubMed

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. PMID:24200980

Baeza, A; Arcos, D; Vallet-Regí, M

2013-12-01

130

Physics of heat generation using magnetic nanoparticles for hyperthermia.  

PubMed

Magnetic nanoparticle hyperthermia and thermal ablation have been actively studied experimentally and theoretically. In this review, we provide a summary of the literature describing the properties of nanometer-scale magnetic materials suspended in biocompatible fluids and their interactions with external magnetic fields. Summarised are the properties and mechanisms understood to be responsible for magnetic heating, and the models developed to understand the behaviour of single-domain magnets exposed to alternating magnetic fields. Linear response theory and its assumptions have provided a useful beginning point; however, its limitations are apparent when nanoparticle heating is measured over a wide range of magnetic fields. Well-developed models (e.g. for magnetisation reversal mechanisms and pseudo-single domain formation) available from other fields of research are explored. Some of the methods described include effects of moment relaxation, anisotropy, nanoparticle and moment rotation mechanisms, interactions and collective behaviour, which have been experimentally identified to be important. Here, we will discuss the implicit assumptions underlying these analytical models and their relevance to experiments. Numerical simulations will be discussed as an alternative to these simple analytical models, including their applicability to experimental data. Finally, guidelines for the design of optimal magnetic nanoparticles will be presented. PMID:24131317

Dennis, Cindi L; Ivkov, Robert

2013-12-01

131

Magnetic Nanoparticle-Phospholipid Interactions in Monolayer Films  

Microsoft Academic Search

Magnetic nanoparticles (MNPs) have potential applications in drug delivery and as anti-cancer agents through hyperthermia, which is induced by hysteric magnetic heating. In order to determine the potential value of the MNPs in these applications, their interactions with cell membranes and phospholipid vesicles must be understood. As the primary structure of the cell membrane is a phospholipid bilayer, a phospholipid

Jennifer Stockdill; John Goff; Kristen Wilson; Judy Riffle; Alan Esker

2003-01-01

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

"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

134

Magnetic Nanoparticle Quantitation with Low Frequency Magnetic Fields: Compensating for Relaxation Effects  

PubMed Central

Quantifying the number of nanoparticles present in tissue is central to many in vivo and in vitro applications. Magnetic nanoparticles can be detected with high sensitivity both in vivo and in vitro using the harmonics of their magnetization produced in a sinusoidal magnetic field. However, relaxation effects damp the magnetic harmonics rendering them of limited use in quantitation. We show that an accurate measure of the number of nanoparticles can be made by correcting for relaxation effects. Correction for relaxation reduced errors of 50% for larger nanoparticles in high relaxation environments to 2%. The result is a method of nanoparticle quantitation capable of in vivo and in vitro applications including histopathology assays, quantitative imaging, drug delivery and thermal therapy preparation. PMID:23867287

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

2013-01-01

135

Polyoxometalate-stabilized, water dispersible Fe2Pt magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic Fe2Pt core-shell nanoparticles with 2 nm cores were synthesized with a monolayer coating of silicotungstate Keggin clusters. The core-shell composition is substantiated by structural analysis performed using high-resolution scanning transmission electron microscopy (HR-STEM) and small angle X-ray scattering (SAXS) in a liquid suspension. The molecular metal oxide cluster shell introduces an enhanced dispersibility of the magnetic Fe-Pt core-shell nanoparticles in aqueous media and thereby opens up new routes to nanoparticle bio-functionalization, for example, using pre-functionalized polyoxometalates.Magnetic Fe2Pt core-shell nanoparticles with 2 nm cores were synthesized with a monolayer coating of silicotungstate Keggin clusters. The core-shell composition is substantiated by structural analysis performed using high-resolution scanning transmission electron microscopy (HR-STEM) and small angle X-ray scattering (SAXS) in a liquid suspension. The molecular metal oxide cluster shell introduces an enhanced dispersibility of the magnetic Fe-Pt core-shell nanoparticles in aqueous media and thereby opens up new routes to nanoparticle bio-functionalization, for example, using pre-functionalized polyoxometalates. Electronic supplementary information (ESI) available: Details of materials, methods and experiments. See DOI: 10.1039/c3nr33374d

Seemann, K. M.; Bauer, A.; Kindervater, J.; Meyer, M.; Besson, C.; Luysberg, M.; Durkin, P.; Pyckhout-Hintzen, W.; Budisa, N.; Georgii, R.; Schneider, C. M.; Kögerler, P.

2013-02-01

136

Magnetic nanoparticle clusters as actuators of ssDNA release.  

PubMed

One of the major areas of research in nanomedicine is the design of drug delivery systems with remotely controllable release of the drug. Despite the enormous progress in the field, this aspect still poses a challenge, especially in terms of selectivity and possible harmful interactions with biological components other than the target. We report an innovative approach for the controlled release of DNA, based on clusters of core-shell magnetic nanoparticles. The primary nanoparticles are functionalized with a single-stranded oligonucleotide, whose pairing with a half-complementary strand in solution induces clusterization. The application of a low frequency (6 KHz) alternating magnetic field induces DNA melting with the release of the single strand that induces clusterization. The possibility of steering and localizing the magnetic nanoparticles, and magnetically actuating the DNA release discloses new perspectives in the field of nucleic-acid based therapy. PMID:24487734

Banchelli, M; Nappini, S; Montis, C; Bonini, M; Canton, P; Berti, D; Baglioni, P

2014-06-01

137

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

138

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

139

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

140

Calixarene-stabilised cobalt nanoparticle rings: Self-assembly and collective magnetic properties Alexander Weia  

E-print Network

Calixarene-stabilised cobalt nanoparticle rings: Self-assembly and collective magnetic properties 10 October 2008) Calixarenes can be used to promote the self-assembly of thermoremanent cobalt phenomenon. Keywords: calixarenes; encapsulation; magnetism; nanoparticles; self-assembly; transmission

Dunin-Borkowski, Rafal E.

141

Dynamic optical probing of the magnetic anisotropy of nickelferrite nanoparticles  

Microsoft Academic Search

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

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

2004-01-01

142

Magnetic properties of ferritin and akaganeite nanoparticles in aqueous suspension.  

PubMed

We have studied the magnetically induced optical birefringence ?n of horse spleen ferritin (HSF) and aqueous suspensions of several different-sized iron oxyhydroxide nanoparticles coated with different polysaccharides mimicking ferritin. The structure and dimensions of the akaganeite mineral core were characterized by XRD and TEM, respectively. The stability of the suspensions in the measurement temperature range from 278 to 358 K was confirmed by UV-Vis absorption spectroscopy. The values of optical polarizability anisotropy ??, magnetic susceptibility anisotropy ??, and permanent magnetic dipole moment ? m of the akaganeite nanoparticles have been estimated on the basis of the temperature dependence of the Cotton-Mouton (C-M) constant. The magnetic birefringence of Fe-sucrose has been described tentatively by different types of Langevin function allowing another estimation of ?? and ? m. The obtained permanent magnetic dipole moment ? m of the studied akaganeite nanoparticles proves small and comparable to that of HSF. The value of ? m is found to increase with decreasing nanoparticle diameter. Observed in a range spanning more than five orders of magnitude, the linear relation between the C-M constant and the iron concentration provides a basis for possible analytical application of the C-M effect in biomedicine. The established relation between the C-M constant and the nanoparticle diameter confirms that the dominant contribution to the measured magnetic birefringence comes from the magnetic susceptibility anisotropy ??. A comparison of the C-M constants of the studied akaganeite nanoparticles with the data obtained for HSF provides evidence that the ferritin core behaves as a non-Euclidian solid. PMID:24532980

Koralewski, Marceli; Pochylski, Miko?aj; Gierszewski, Jacek

2013-01-01

143

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

144

Characterization of magnetic nanoparticles using Magnetic Hyperthermia System (MHS) for the application in cancer treatment  

NASA Astrophysics Data System (ADS)

In this study, the heating profiles of various concentrations of three Fe3O4 magnetic nanoparticle systems were measured when the nanoparticles were exposed to alternating magnetic fields in a RF Magnetic Hyperthermia System. The Fe3O4 core nanoparticles of each system were approximately 10nm in diameter, but each system had different nanoparticle configurations and surface modifications. The heating profiles were used to investigate the dominant heating mechanism, the heat transfer into the surrounding fluid, and the overall effectiveness of each nanoparticle system for possible use in hyperthermia cancer treatments. Magnetization measurements showed that all samples were superparamagnetic in nature with almost zero retentivity and coercivity. For all samples, the saturation magnetization was observed to increase linearly with increasing concentration of Fe3O4. Five different concentrations of the three Fe3O4 nanoparticle samples were exposed to a 13.56 MHz alternating magnetic field with an amplitude of 4500 A/m, while the solution temperature was measured as a function of time using an optical fiber temperature probe. A correlation was observed between the heating rate, the initial susceptibility, and the type of surface modification of the Fe3O4 nanoparticles.

Sadat, M. E.; Patel, Ronak; Mast, David B.; Shi, Donglu; Bud'Ko, Sergey L.; Zhang, Jiaming; Xu, Hong

2013-03-01

145

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

146

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

147

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

148

Magnetic nanoparticles of core-shell structure for recoverable photocatalysts  

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

149

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

150

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

151

Physical justification for negative remanent magnetization in homogeneous nanoparticles.  

PubMed

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

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

2014-01-01

152

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

153

Characterization of iron oxide-dextran magnetic nanoparticle suspensions  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles, with structures from core-shell to nanocrystallites in a matrix, are candidates for use in biomedical applications. "Superparamagnetic iron oxide" (SPIO) nanoparticles are nanocrystallites of iron oxide in a dextran matrix, with sizes between 20nm and 250nm. Dynamic light scattering (DLS), transmission electron microscopy (TEM), atomic force microscopy (AFM), and hysteresis measurements were used for structural and magnetic characterization. Additionally, cryoquench-TEM was performed, allowing direct imaging without false aggregation from drying. The DLS-determined size of the particles is 250nm, but cryoquench-TEM yields a smaller size of 150nm. In addition, the particles are relatively well-dispersed, but dimers and trimers are observed. This corresponds with the evidence of weak interactions in magnetic hysteresis measurements. Further magnetic characterization will provide information on how the magnetic properties of these SPIO particles correlate with their size and structure.

Shih, J.; Bai, R.; Chiou, W.; Briber, R. M.; Borchers, J. A.; Dennis, C. L.; Gruettner, C.

2011-03-01

154

Synthesis and characterizations of novel magnetic and plasmonic nanoparticles  

NASA Astrophysics Data System (ADS)

This dissertation reports the colloidal synthesis of iron silicide, hafnium oxide core-gold shell and water soluble iron-gold alloy for the first time. As the first part of the experimentation, plasmonic and superparamagnetic nanoparticles of gold and iron are synthesized in the form of core-shell and alloy. The purpose of making these nanoparticles is that the core-shell and alloy nanoparticles exhibit enhanced properties and new functionality due to close proximity of two functionally different components. The synthesis of core-shell and alloy nanoparticles is of special interest for possible application towards magnetic hyperthermia, catalysis and drug delivery. The iron-gold core-shell nanoparticles prepared in the reverse micelles reflux in high boiling point solvent (diphenyl ether) in presence of oleic acid and oleyl amine results in the formation of monodisperse core-shell nanoparticles. The second part of the experimentation includes the preparation of water soluble iron-gold alloy nanoparticles. The alloy nanoparticles are prepared for the first time at relatively low temperature (110 °C). The use of hydrophilic ligand 3-mercapto-1-propane sulphonic acid ensures the aqueous solubility of the alloy nanoparticles. Next, hafnium oxide core-gold shell nanoparticles are prepared for the first time using high temperature reduction method. These nanoparticles are potentially important as a high kappa material in semiconductor industry. Fourth, a new type of material called iron silicide is prepared in solution phase. The material has been prepared before but not in a colloidal solution. The Fe3Si obtained is superparamagnetic. Another phase beta-FeSi 2 is a low band gap (0.85 eV) semiconductor and is sustainable and environmentally friendly. At last, the iron monosilicide (FeSi) and beta-FeSi2 are also prepared by heating iron-gold core-shell and alloy nanoparticles on silicon (111) substrate. The nucleation of gaseous silicon precursor on the melted nanoparticles results the formation of nanodomains of FeSi and beta-FeSi 2. A practical application of these nanoparticles is an important next step of this research. Further improvement in the synthesis of beta-FeSi 2 nanoparticles by colloidal synthetic approach and its application in solar cell is a future goal.

Dahal, Naween

155

Ferrimagnetic nanoparticles for self-controlled magnetic hyperthermia  

NASA Astrophysics Data System (ADS)

Based on the Heisenberg model including single-site uniaxial anisotropy and using a Green's function technique we studied the influence of size and composition effects on the Curie temperature T C , saturation magnetization M S and coercivity H C of spherical nanoparticles with a structural formula M e 1- x Zn x Fe2O4, Me = Ni, Cu, Co, Mn. It is shown that for x = 0.4-0.5 and d = 10-20 nm these nanoparticles have a T C = 315 K and are suitable for a self-controlled magnetic hyperthermia.

Apostolov, A. T.; Apostolova, I. N.; Wesselinowa, J. M.

2013-11-01

156

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

157

Millimeter Scale Alignment of Magnetic Nanoparticle Functionalized Microtubules in Magnetic Fields  

E-print Network

polymerization.6 In this communication, we report the first instance of microtubule functionalization with cobalt ferrite nanoparticles (CoFe2O4) and the facile use of an externally applied magnetic field to control

Hancock, William O.

158

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

159

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

160

Superparamagnetic nanoparticles for enhanced magnetic resonance and multimodal imaging  

NASA Astrophysics Data System (ADS)

Magnetic resonance imaging (MRI) is a powerful tool for noninvasive tomographic imaging of biological systems with high spatial and temporal resolution. Superparamagnetic (SPM) nanoparticles have emerged as highly effective MR contrast agents due to their biocompatibility, ease of surface modification and magnetic properties. Conventional nanoparticle contrast agents suffer from difficult synthetic reproducibility, polydisperse sizes and weak magnetism. Numerous synthetic techniques and nanoparticle formulations have been developed to overcome these barriers. However, there are still major limitations in the development of new nanoparticle-based probes for MR and multimodal imaging including low signal amplification and absence of biochemical reporters. To address these issues, a set of multimodal (T2/optical) and dual contrast (T1/T2) nanoparticle probes has been developed. Their unique magnetic properties and imaging capabilities were thoroughly explored. An enzyme-activatable contrast agent is currently being developed as an innovative means for early in vivo detection of cancer at the cellular level. Multimodal probes function by combining the strengths of multiple imaging techniques into a single agent. Co-registration of data obtained by multiple imaging modalities validates the data, enhancing its quality and reliability. A series of T2/optical probes were successfully synthesized by attachment of a fluorescent dye to the surface of different types of nanoparticles. The multimodal nanoparticles generated sufficient MR and fluorescence signal to image transplanted islets in vivo. Dual contrast T1/T2 imaging probes were designed to overcome disadvantages inherent in the individual T1 and T2 components. A class of T1/T2 agents was developed consisting of a gadolinium (III) complex (DTPA chelate or DO3A macrocycle) conjugated to a biocompatible silica-coated metal oxide nanoparticle through a disulfide linker. The disulfide linker has the ability to be reduced in vivo by glutathione, releasing large payloads of signal-enhancing T1 probes into the surrounding environment. Optimization of the agent occurred over three sequential generations, with each generation addressing a new challenge. The result was a T2 nanoparticle containing high levels of conjugated T1 complex demonstrating enhanced MR relaxation properties. The probes created here have the potential to play a key role in the advancement of nanoparticle-based agents in biomedical MRI applications.

Sikma, Elise Ann Schultz

161

X-space MPI: magnetic nanoparticles for safe medical imaging.  

PubMed

One quarter of all iodinated contrast X-ray clinical imaging studies are now performed on Chronic Kidney Disease (CKD) patients. Unfortunately, the iodine contrast agent used in X-ray is often toxic to CKD patients' weak kidneys, leading to significant morbidity and mortality. Hence, we are pioneering a new medical imaging method, called Magnetic Particle Imaging (MPI), to replace X-ray and CT iodinated angiography, especially for CKD patients. MPI uses magnetic nanoparticle contrast agents that are much safer than iodine for CKD patients. MPI already offers superb contrast and extraordinary sensitivity. The iron oxide nanoparticle tracers required for MPI are also used in MRI, and some are already approved for human use, but the contrast agents are far more effective at illuminating blood vessels when used in the MPI modality. We have recently developed a systems theoretic framework for MPI called x-space MPI, which has already dramatically improved the speed and robustness of MPI image reconstruction. X-space MPI has allowed us to optimize the hardware for fi ve MPI scanners. Moreover, x-space MPI provides a powerful framework for optimizing the size and magnetic properties of the iron oxide nanoparticle tracers used in MPI. Currently MPI nanoparticles have diameters in the 10-20 nanometer range, enabling millimeter-scale resolution in small animals. X-space MPI theory predicts that larger nanoparticles could enable up to 250 micrometer resolution imaging, which would represent a major breakthrough in safe imaging for CKD patients. PMID:22988557

Goodwill, Patrick William; Saritas, Emine Ulku; Croft, Laura Rose; Kim, Tyson N; Krishnan, Kannan M; Schaffer, David V; Conolly, Steven M

2012-07-24

162

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

Microsoft Academic Search

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

Viara Ivanova; Petia Petrova; Jordan Hristov

2011-01-01

163

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

164

Lanthanide doped nanoparticles as remote sensors for magnetic fields  

NASA Astrophysics Data System (ADS)

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.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. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr02983f

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

2014-09-01

165

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

166

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

PubMed Central

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

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

2013-01-01

167

A two rotor model with spin for magnetic nanoparticles.  

PubMed

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

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

2014-11-21

168

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

169

Engineering Magnetic nanoparticles are of interest in a variety of  

E-print Network

in destroying cancer cells. Biosketch Carlos Rinaldi obtained his undergraduate degree in Chemical Engineering will summarize our recent work on suspensions of magnetic nanoparticles subjected to constant and time- varying in temperature. Such an effect can be applied to the treatment of certain diseases such as cancer. I will present

170

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

171

Core/shell magnetism in NiO nanoparticles  

NASA Astrophysics Data System (ADS)

The anomalous appearance of a ferromagnetic moment in nominally antiferromagnetic nanoparticles has been known about since Néel, but never well understood. We present proof of the core/shell model of magnetism in antiferromagnetic NiO nanoparticles (NP) using neutron diffraction. Nickel oxide nanoparticles were produced in a large quantity by a novel continuous hydrothermal flow synthesis method. The antiferromagnetic nature of the nanoparticles allowed the structural and the magnetic diffraction peaks to be completely separated. Using both the microstructure option in "Fullprof" microstructure fitting suite and convolution techniques, we determined the NP consisted of an ordered antiferromagnetic core 5.2(2) nm in diameter surrounded by a disordered shell 0.7(2) nm thick. Further magnetic measurements showed that this disordered shell possess a significant polarisable magnetisation, up to a fifth that of pure nickel. They also indicate that two magnetic transitions occur between 400 and 10 K; around 350 K, there is a broad transition from paramagnetic to a form of superparamagnetism, then near 30 K there is a transition to a higher anisotropy state. Differences in field cooled and zero field cooled hysteresis loops were found, though with no evidence of exchange bias effects.

Cooper, J. F. K.; Ionescu, A.; Langford, R. M.; Ziebeck, K. R. A.; Barnes, C. H. W.; Gruar, R.; Tighe, C.; Darr, J. A.; Thanh, N. T. K.; Ouladdiaf, B.

2013-08-01

172

Magnetic nanoparticle and magnetic field assisted siRNA delivery in vitro.  

PubMed

This chapter describes how to design and conduct experiments to deliver siRNA to adherent cell cultures in vitro by magnetic force-assisted transfection using self-assembled complexes of small interfering RNA (siRNA) and cationic lipids or polymers that are associated with magnetic nanoparticles (MNPs). These magnetic complexes are targeted to the cell surface by the application of a gradient magnetic field. A further development of the magnetic drug-targeting concept is combining it with an ultrasound-triggered delivery using magnetic microbubbles as a carrier for gene or drug delivery. For this purpose, selected MNPs, phospholipids, and siRNAs are assembled in the presence of perfluorocarbon gas into flexible formulations of magnetic lipospheres (microbubbles). Methods are described how to accomplish the synthesis of magnetic nanoparticles for magnetofection and how to test the association of siRNA with the magnetic components of the transfection vector. A simple method is described to evaluate magnetic responsiveness of the magnetic siRNA transfection complexes and estimate the complex loading with magnetic nanoparticles. Procedures are provided for the preparation of magnetic lipoplexes and polyplexes of siRNA as well as magnetic microbubbles for magnetofection and downregulation of the target gene expression analysis with account for the toxicity determined using an MTT-based respiration activity test. A modification of the magnetic transfection triplexes with INF-7, fusogenic peptide, is described resulting in reporter gene silencing improvement in HeLa, Caco-2, and ARPE-19 cells. The methods described can also be useful for screening vector compositions and novel magnetic nanoparticle preparations for optimized siRNA transfection by magnetofection in any cell type. PMID:25319646

Mykhaylyk, Olga; Sanchez-Antequera, Yolanda; Vlaskou, Dialechti; Cerda, Maria Belen; Bokharaei, Mehrdad; Hammerschmid, Edelburga; Anton, Martina; Plank, Christian

2015-01-01

173

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

174

Magnetic heating by cobalt ferrite nanoparticles  

Microsoft Academic Search

In the quest for suitable materials for hyperthermia we explored the preparation and properties of nanoparticles of Co ferrite. The material was produced by coprecipitation from water solution of Co and Fe chlorides and afterwards annealed at 400, 600 and 800 °C. The resulting particles were characterized by XRD, TEM, Mössbauer spectroscopy, and dc and ac magnetometry. The heating experiments

M. Veverka; P. Veverka; O. Kaman; A. Lancok; K. Záveta; E. Pollert; K. Knízek; J. Bohácek; M. Benes; P. Kaspar; E. Duguet; S. Vasseur

2007-01-01

175

Coupled stochastic dynamics of magnetic moment and anisotropy axis of a magnetic nanoparticle.  

PubMed

An algorithm is developed for numerical simulation of coupled stochastic dynamics of magnetic moment and magnetic anisotropy axis of a nanoparticle. Time-correlation functions of the magnetic moment and its components longitudinal and transverse to the magnetic anisotropy axis are calculated by averaging along the stochastic trajectory. The longitudinal and transverse relaxation times are found by fitting the time correlation functions. Existing theoretical relations derived by the effective field approach in the limit of small fields are confirmed. The time-correlation functions of magnetic moments of nanoparticles in dependence on their properties are calculated numerically for arbitrary large magnetic fields and it is shown that they may be approximated by a sum of several exponentials. These results are applied for the calculation of relaxivity parameters of nuclear magnetic resonance (NMR) imaging in dependence on the field strength. PMID:23367948

Taukulis, R; C?bers, A

2012-12-01

176

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

E-print Network

Intracellular performance of tailored nanoparticle tracers in magnetic particle imaging Hamed Arami-intensity pulsed ultrasound on biocompatibility and cellular uptake of chitosan-tripolyphosphate nanoparticles by electrospinning as a magnetic nanoparticle delivery approach J. Appl. Phys. 115, 17B908 (2014); 10

Krishnan, Kannan M.

177

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

178

Scaling of transverse nuclear magnetic relaxation due to magnetic nanoparticle aggregation  

PubMed Central

The aggregation of superparamagnetic iron oxide (SPIO) nanoparticles decreases the transverse nuclear magnetic resonance (NMR) relaxation time T2CP of adjacent water molecules measured by a Carr-Purcell-Meiboom-Gill (CPMG) pulse-echo sequence. This effect is commonly used to measure the concentrations of a variety of small molecules. We perform extensive Monte Carlo simulations of water diffusing around SPIO nanoparticle aggregates to determine the relationship between T2CP and details of the aggregate. We find that in the motional averaging regime T2CP scales as a power law with the number N of nanoparticles in an aggregate. The specific scaling is dependent on the fractal dimension d of the aggregates. We find T2CP?N?0.44 for aggregates with d = 2.2, a value typical of diffusion limited aggregation. We also find that in two-nanoparticle systems, T2CP is strongly dependent on the orientation of the two nanoparticles relative to the external magnetic field, which implies that it may be possible to sense the orientation of a two-nanoparticle aggregate. To optimize the sensitivity of SPIO nanoparticle sensors, we propose that it is best to have aggregates with few nanoparticles, close together, measured with long pulse-echo times. PMID:20689678

Brown, Keith A.; Vassiliou, Christophoros C.; Issadore, David; Berezovsky, Jesse; Cima, Michael J.; Westervelt, R. M.

2010-01-01

179

Scaling of transverse nuclear magnetic relaxation due to magnetic nanoparticle aggregation.  

PubMed

The aggregation of superparamagnetic iron oxide (SPIO) nanoparticles decreases the transverse nuclear magnetic resonance (NMR) relaxation time T2CP of adjacent water molecules measured by a Carr-Purcell-Meiboom-Gill (CPMG) pulse-echo sequence. This effect is commonly used to measure the concentrations of a variety of small molecules. We perform extensive Monte Carlo simulations of water diffusing around SPIO nanoparticle aggregates to determine the relationship between T2CP and details of the aggregate. We find that in the motional averaging regime T2CP scales as a power law with the number N of nanoparticles in an aggregate. The specific scaling is dependent on the fractal dimension d of the aggregates. We find T2CP?N-0.44 for aggregates with d = 2.2, a value typical of diffusion limited aggregation. We also find that in two-nanoparticle systems, T2CP is strongly dependent on the orientation of the two nanoparticles relative to the external magnetic field, which implies that it may be possible to sense the orientation of a two-nanoparticle aggregate. To optimize the sensitivity of SPIO nanoparticle sensors, we propose that it is best to have aggregates with few nanoparticles, close together, measured with long pulse-echo times. PMID:20689678

Brown, Keith A; Vassiliou, Christophoros C; Issadore, David; Berezovsky, Jesse; Cima, Michael J; Westervelt, R M

2010-10-01

180

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

181

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

PubMed

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. PMID:25422526

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

2014-11-01

182

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

183

Magnetically-Responsive Nanoparticles for Vectored Delivery of Cancer Therapeutics  

NASA Astrophysics Data System (ADS)

We propose that physical targeting of therapeutics to tumors using magnetically-responsive nanoparticles (MNPs) will enhance intratumoral drug levels compared to free drugs in an effort to overcome tumor resistance. We evaluated the feasibility of magnetic enhancement of tumor extravasation of systemically-administered MNPs in human xenografts implanted in the mammary fatpads of nude mice. Mice with orthotopic tumors were injected systemically with MNPs, with a focused magnetic field juxtaposed over the tumor. Magnetic resonance imaging and scanning electron microscopy both indicated successful tumor localization of MNPs. Next, MNPs were modified with poly-ethylene-glycol (PEG) and their clearance compared by estimating signal attenuation in liver due to iron accumulation. The results suggested that PEG substitution could retard the rate of MNP plasma clearance, which may allow greater magnetically-enhanced tumor localization. We propose that this technology is clinically scalable to many types of both superficial as well as some viscerable tumors with existing magnetic technology.

Klostergaard, Jim; Bankson, James; Woodward, Wendy; Gibson, Don; Seeney, Charles

2010-12-01

184

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

185

Magnetic properties of ball-milled Mn nanoparticles  

NASA Astrophysics Data System (ADS)

Nanoparticles of Mn of sizes < 500 Å were prepared by the ball-milling technique. The temperature dependence of the magnetic susceptibility ? showed systematic variation with particle size. Peaks observed in ? were attributed to the magnetic ordering of the oxides Mn 3O 4and MnO. Peaks found in ?( ?T) / ?T were associated with the Neel temperature of ? -Mn. We estimated that our samples contain about 0.4% of Mn 3O 4. This low concentration of Mn 3O 4was not detected by X-ray diffraction experiments but contributed significantly to the magnetization measurements.

Abdul-Razzaq, W.; Wu, Min

2001-04-01

186

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

187

Hard magnetic properties of FePd nanoparticles  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

188

Structural And Magnetic Properties Of Ni-Zn Ferrite Nanoparticles  

Microsoft Academic Search

Nickel zinc ferrite nanoparticles of the composition NixZn1-xFe2O4 (x = 0.1, 0.3, 0.5) have been synthesized by the chemical co-precipitation method. The samples were characterized by X-ray diffraction, TEM, EPR, DC magnetization and AC susceptibility measurements. The X-ray diffraction patterns confirm the synthesis of single crystalline phase of NixZn1-xFe2O4 (x = 0.1, 0.3, 0.5) nanoparticles. Lattice parameter decreases with the

G. S. Shahane; Ashok Kumar; R. P. Pant; Krishan Lal

2010-01-01

189

Magnetic properties and energy absorption of CoFe2O4 nanoparticles for magnetic hyperthermia  

E-print Network

We have studied the magnetic and power absorption properties of three samples of CoFe2O4 nanoparticles with sizes from 5 to 12 nm prepared by thermal decomposition of Fe (acac)3 and Co(acac)2 at high temperatures. The blocking temperatures TB estimated from magnetization M(T) curves spanned the range 180 < TB < 320 K, reflecting the large magnetocrystalline anisotropy of these nanoparticles. Accordingly, high coercive fields HC \\approx 1.4 - 1.7 T were observed at low temperatures. Specific Power Absorption (SPA) experiments carried out in ac magnetic fields indicated that, besides particle volume, the effective magnetic anisotropy is a key parameter determining the absorption efficiency. SPA values as high as 98 W/g were obtained for nanoparticles with average size of \\approx12 nm.

Torres, T E; Morales, M P; Ibarra, A; Marquina, C; Ibarra, M R; Goya, G F; 10.1088/1742-6596/200/7/072101

2011-01-01

190

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

191

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

192

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

193

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

PubMed Central

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 neodymium-boron-iron magnets (80 T/m to 130 T/m in central plane between magnets), a rabbit ear model, and systemically-delivered 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. PMID:24073325

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

2013-01-01

194

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

195

Color-tunable magnetic and luminescent hybrid nanoparticles: Synthesis, optical and magnetic properties  

NASA Astrophysics Data System (ADS)

A facile method for synthesizing color-tunable magnetic and luminescent hybrid bifunctional nanoparticles is presented. A series of CdSe/ZnS core-shell quantum dots (QDs) with different sizes were successfully fabricated and self-assembled to Fe3O4 magnetic nanoparticles (MNP), which were subsequently coated with a polyethyleneimine (PEI) layer to prevent large aggregates. The hydrophobic QDs capped with trioctylphosphine oxide (TOPO) formed a coating surrounding MNP, and were transferred into hydrophilic phase by PEI with high efficiency. The samples were characterized by TEM, FT-IR, XRD, EDS, UV-vis spectrophotometer, fluorescent spectrophotometer and PPMS. Results show that the original properties of the nanoparticles were well-preserved in the hybrid structure. All MNP-QDs hybrid nanoparticles showed paramagnetic behavior and the nanocomposites were still highly luminescent with no shift in the PL peak position.

Lou, Lei; Yu, Ke; Wang, Yiting; Zhu, Ziqiang

2012-02-01

196

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

197

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

198

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

NASA Astrophysics Data System (ADS)

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.; Qi, B.; Pearson, T.; Cordeau, Y.; Mefford, O. T.; Crawford, T. M.

2014-05-01

199

MnZnFe nanoparticles for self-controlled magnetic hyperthermia  

NASA Astrophysics Data System (ADS)

Manganese zinc iron magnetic nanoparticles were synthesized by a co-precipitation method for application as hyperthermia inducing agents. The structure, morphology and magnetic properties of the nanoparticles are characterized using scanning electron microscopy, X-ray diffraction, and a superconducting quantum interference device. The magnetic properties being investigated include Curie temperature, saturation magnetization, remnant magnetization, coercive field, and hysteresis. The study showed that adjusting the Mn contribution to the particles contributed to the adjustment of all magnetic properties of the complex.

Hejase, Hassan; Hayek, Saleh S.; Qadri, Shahnaz; Haik, Yousef

2012-11-01

200

Preparation and characterization of carboxyl functionalization of chitosan derivative magnetic nanoparticles  

Microsoft Academic Search

The functionalized magnetic Fe3O4-chitosan derivative nanoparticles have been prepared by the covalent binding of alpha-ketoglutaric acid chitosan (KCTS) onto the surface of Fe3O4 magnetic nanoparticles via carbodiimide activation. Transmission electron microscopy (TEM) showed that the KCTS-bound Fe3O4 nanoparticles were regular spheres with a mean diameter of 26nm. X-ray diffraction (XRD) patterns indicated that the Fe3O4 nanoparticles were pure Fe3O4 with

Gui-yin Li; Ke-long Huang; Yu-ren Jiang; Ping Ding; Dong-liang Yang

2008-01-01

201

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

202

Magnetic Prussian blue nanoparticles for targeted photothermal therapy under magnetic resonance imaging guidance.  

PubMed

This paper reported a core-shell nanotheranostic agent by growing Prussian blue (PB) nanoshells of 3-6 nm around superparamagnetic Fe3O4 nanocores for targeted photothermal therapy of cancer under magnetic resonance imaging (MRI) guidance. Both in vitro and in vivo experiments proved that the Fe3O4@PB core-shell nanoparticles showed significant contrast enhancement for T2-weighted MRI with the relaxivity value of 58.9 mM(-1)·s(-1). Simultaneously, the composite nanoparticles exhibited a high photothermal effect under irradiation of a near-infrared laser due to the strong absorption of PB nanoshells, which led to more than 80% death of HeLa cells with only 0.016 mg·mL(-1) of the nanoparticles with the aid of the magnetic targeting effect. Using tumor-bearing nude mice as the model, the near-infrared laser light ablated the tumor effectively in the presence of the Fe3O4@PB nanoparticles and the tumor growth inhibition was evaluated to be 87.2%. Capabilities of MRI, magnetic targeting, and photothermal therapy were thus integrated into a single agent to allow efficient MRI-guided targeted photothermal therapy. Most importantly, both PB and Fe3O4 nanoparticles were already clinically approved drugs, so the Fe3O4@PB nanoparticles as a theranostic nanomedicine would be particularly promising for clinical applications in the human body due to the reliable biosafety. PMID:25109612

Fu, Guanglei; Liu, Wei; Li, Yanyan; Jin, Yushen; Jiang, Lingdong; Liang, Xiaolong; Feng, Shanshan; Dai, Zhifei

2014-09-17

203

Synthesis and functionalisation of magnetic nanoparticles for hyperthermia applications.  

PubMed

A summary of recent developments in the synthesis, stabilisation and coating of magnetic iron oxide nanoparticles for hyperthermia applications is presented. Methods for synthesis in aqueous, organic and microemulsion systems are reviewed together with the resulting heating rates of the nanoparticles. Different stabilisation mechanisms for iron oxide nanoparticles from aqueous and organic media are discussed as intermediates for further coating and functionalisation. Coating with silica and/or polysaccharides is mainly used for design of nanoparticles especially for targeted hyperthermia application. These coatings permit versatile functionalisation as a basis for conjugating biomolecules, e.g. antibodies or peptides. Various strategies to conjugate biomolecules on the particle surface are discussed, with emphasis on methods that preserve biofunctionality after immobilisation. The efficiency of established methods such as carbodiimide coupling and oriented conjugation strategies is compared with new developments such as the bioorthogonal approaches that are based on the cycloaddition of strain-promoted alkynes with azides or nitrones. For targeted hyperthermia applications the study of the formation of a protein corona around nanoparticles with site-specific biomolecules on the surface is essential to achieve improved circulation times in the blood and reduced non-specific uptake by non-targeted organs for a high specific accumulation in the target tissue. PMID:24099465

Grüttner, Cordula; Müller, Knut; Teller, Joachim; Westphal, Fritz

2013-12-01

204

Cellular response to magnetic nanoparticles "PEGylated" via surface-initiated atom transfer radical polymerization.  

PubMed

A new method to PEGylate magnetic nanoparticles with a dense layer of poly(poly(ethylene glycol) monomethacrylate) (P(PEGMA)) by surface-initiated atom transfer radical polymerization (ATRP) is reported. In this approach, an initiator for ATRP was first immobilized onto the magnetic nanoparticle surface, and then P(PEGMA) was grafted onto the surface of magnetic nanoparticle via copper-mediated ATRP. The modified nanoparticles were subjected to detailed characterization using FTIR, XPS, and TGA. The P(PEGMA)-immobilized nanoparticles dispersed well in aqueous media. The saturation magnetization values of the P(PEGMA)-immobilized nanoparticles were 19 emu/g and 11 emu/g after 2 and 4 h polymerization respectively, compared to 52 emu/g for the pristine magnetic nanoparticles. The response of macrophage cells to pristine and P(PEGMA)-immobilized nanoparticles was compared. The results showed that the macrophage cells are very effective in cleaning up the pristine magnetic nanoparticles. With the P(PEGMA)-immobilized nanoparticles, the amount of nanoparticles internalized into the cells is greatly reduced to <2 pg/cell over a 5 day period. With this amount of nanoparticles uptake, no significant cytotoxicity effects were observed. PMID:16529418

Hu, Feixiong; Neoh, Koon Gee; Cen, Lian; Kang, En-Tang

2006-03-01

205

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

206

Stimuli-responsive magnetic nanoparticles for monoclonal antibody purification.  

PubMed

Monoclonal antibodies (mAbs) are important therapeutic proteins. One of the challenges facing large-scale production of monoclonal antibodies is the capacity bottleneck in downstream processing, which can be circumvented by using magnetic stimuli-responsive polymer nanoparticles. In this work, stimuli-responsive magnetic particles composed of a magnetic poly(methyl methacrylate) core with a poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAM-co-AA)) shell cross-linked with N, N'-methylenebisacrylamide were prepared by miniemulsion polymerization. The particles were shown to have an average hydrodynamic diameter of 317 nm at 18°C, which decreased to 277 nm at 41°C due to the collapse of the thermo-responsive shell. The particles were superparamagnetic in behavior and exhibited a saturation magnetization of 12.6 emu/g. Subsequently, we evaluated the potential of these negatively charged stimuli-responsive magnetic particles in the purification of a monoclonal antibody from a diafiltered CHO cell culture supernatant by cation exchange. The adsorption of antibodies onto P(NIPAM-co-AA)-coated nanoparticles was highly selective and allowed for the recovery of approximately 94% of the mAb. Different elution strategies were employed providing highly pure mAb fractions with host cell protein (HCP) removal greater than 98%. By exploring the stimuli-responsive properties of the particles, shorter magnetic separation times were possible without significant differences in product yield and purity. PMID:23420794

Borlido, Luís; Moura, Leila; Azevedo, Ana M; Roque, Ana C A; Aires-Barros, Maria R; Farinha, José Paulo S

2013-06-01

207

Ferromagnetic nanoparticles for magnetic hyperthermia and thermoablation therapy  

NASA Astrophysics Data System (ADS)

The use of ferromagnetic nanoparticles for hyperthermia and thermoablation therapies has shown great promise in the field of nanobiomedicine. Even local hyperthermia offers numerous advantages as a novel cancer therapy; however, it requires a remarkably high heating power of more than 1 kW g-1 for heat agents. As a candidate for high heat generation, we focus on ferromagnetic nanoparticles and compare their physical properties with those of superparamagnetic substances. Numerical simulations for ideal single-domain ferromagnetic nanoparticles with cubic and uniaxial magnetic symmetries were carried out and MH curves together with minor loops were obtained. From the simulation, the efficient use of an alternating magnetic field (AMF) having a limited amplitude was discussed. Co-ferrite nanoparticles with various magnitudes of coercive force were produced by co-precipitation and a hydrothermal process. A maximum specific loss power of 420 W g-1 was obtained using an AMF at 117 kHz with H0 = 51.4 kA m-1 (640 Oe). The relaxation behaviour in the ferromagnetic state below the superparamagnetic blocking temperature was examined by Mössbauer spectroscopy.

Kita, Eiji; Oda, Tatsuya; Kayano, Takeru; Sato, Suguru; Minagawa, Makoto; Yanagihara, Hideto; Kishimoto, Mikio; Mitsumata, Chiharu; Hashimoto, Shinji; Yamada, Keiichi; Ohkohchi, Nobuhiro

2010-12-01

208

The synthesis, characterization, and application of multifunctional magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

In recent years, the field of nanotechnology has been one of extreme activity. Among other things, this activity is driven by the push for consumer technologies that are lighter, stronger, and most importantly smaller. With this push from the everyday consumer, the need for a basic understanding of the underlying physics of nanoscale materials has never been more evident. In this dissertation, the author investigates the many physical differences, in particular the differences in the magnetic properties, between nanoscale materials and their bulk counterparts. Starting out with a brief overview of magnetism, the author sets out to explore the fantastic changes in the magnetic properties of materials that occur when the physical dimensions of the materials become smaller than typical magnetic length scales. Among the first differences noticed arises when nanoscale ferromagnets are investigated. While the magnetic properties of bulk ferromagnets are governed by magnetic domain dynamics, when a material becomes small enough that only one domain is possible, a new type of magnetic behavior known as superparamagnetism arises. While this superparamagnetic behavior is well understood in terms of thermally activated spin reversal through an energy barrier, many factors, such as interactions between separate nanoparticles, cause deviations from this simple picture. The effects of these factors are investigated. In addition to the effects of interactions, the relation of nanoscale magnetics and its coupling to the dielectric properties of nanoparticles is investigated. This investigation, motivated by recent research focusing on the search for materials whose magnetic and electronic properties are influenced by each other, shows that nanomaterials can show a coupling between these properties that isn't necessarily the intrinsic coupling of the two properties, but an effect from the surface layers of nanoparticles, which are generally ignored in bulk systems due to the fact that they make up such a small percentage of the overall material. However, in nanoscale systems, the surface layers become much more involved in the determination of the overall behavior of the system as they are no longer a small percentage of the overall system, and cannot be ignored. A third investigation looks at magnetodielectric coupling that occurs in bulk Mn3O4 as a result of spin-lattice coupling with the lattice and the long-range magnetic order that develops in the system at low temperature. The motivation to study this bulk system becomes evident to the general theme of this dissertation when one asks the question, can this long-range order (extending over many unit cells of the lattice) occur in nanoscale systems (where only a few unit cells of material are present)? Preliminary data suggests that these long-range orders that occur in the bulk are not feasible in the nanoscale material. Finally, as consumer driven technology grows, the need for a single material that can be altered for use in a wide variety of applications becomes increasingly more evident. It is with this motivation that the author investigates the ability to tune the blocking temperature of an Fe3O4 nanoparticle system through cobalt doping, effectively changing the magnetocrystalline anisotropy of the system. The author finds that up to small cobalt concentrations, the magnetocrystalline anisotropy was able to be linearly increased by increasing the amount of cobalt in the system, thus providing a nanoparticle system whose blocking temperature is effectively tunable. In addition to this tuning using the cobalt doping to change the anisotropy, it was found that altering the size of the nanoparticles was also an effective way to controllably tune the blocking temperature of a nanoparticle system. In addition to the author's main research aimed at this dissertation, the author provides a small outline of some work that was done outside of the scope of his dissertation research. It is shown that while this work did not directly contribute to the dissertation topic, it did broaden th

Tackett, Ronald J.

209

Brain tumor targeting of magnetic nanoparticles for potential drug delivery: Effect of administration route and magnetic field topography  

Microsoft Academic Search

Our previous studies demonstrated feasibility of magnetically-mediated retention of iron oxide nanoparticles in brain tumors after intravascular administration. The purpose of this study was to elucidate strategies for further improvement of this promising approach. In particular, we explored administration of the nanoparticles via a non-occluded carotid artery as a way to increase the passive exposure of tumor vasculature to nanoparticles

Beata Chertok; Allan E. David; Victor C. Yang

2011-01-01

210

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

211

Characterization of magnetic nanoparticle by dynamic light scattering.  

PubMed

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

Lim, Jitkang; Yeap, Swee Pin; Che, Hui Xin; Low, Siew Chun

2013-01-01

212

Molecular dynamics simulations of proton transverse relaxation times in suspensions of magnetic nanoparticles.  

PubMed

In this work we have analyzed the influence of various factors on the transverse relaxation times T2 of water protons in suspension of magnetic nanoparticles. For that purpose we developed a full molecular dynamics force field which includes the effects of dispersion interactions between magnetic nanoparticles and water molecules, electrostatic interactions between charged nanoparticles and magnetic dipole-dipole and dipole-external field interactions. We also accounted for the magnetization reversal within the nanoparticles body frames due to finite magnetic anisotropy barriers. The force field together with the Langevin dynamics imposed on water molecules and the nanoparticles allowed us to monitor the dephasing of water protons in real time. Thus, we were able to determine the T2 relaxation times including the effects of the adsorption of water on the nanoparticles' surfaces, thermal fluctuations of the orientation of nanoparticles' magnetizations as well as the effects of the core-shell architecture of nanoparticles and their agglomeration into clusters. We found that there exists an optimal cluster size for which T2 is minimized and that the retardation of water molecules motion, due to adsorption on the nanoparticles surfaces, has some effect in the measured T2 times. The typical strengths of the external magnetic fields in MRI are enough to keep the magnetizations fixed along the field direction, however, in the case of low magnetic fields, we observed significant enhancement of T2 due to thermal fluctuations of the orientations of magnetizations. PMID:25313483

Panczyk, Tomasz; Konczak, Lukasz; Zapotoczny, Szczepan; Szabelski, Pawel; Nowakowska, Maria

2015-01-01

213

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

214

Monodispersed magnetite nanoparticles optimized for magnetic fluid hyperthermia: Implications in biological systems  

E-print Network

Monodispersed magnetite nanoparticles optimized for magnetic fluid hyperthermia: Implications 2011) Magnetite (Fe3O4) nanoparticles (MNPs) are suitable materials for Magnetic Fluid Hyperthermia of Physics. [doi:10.1063/1.3556948] I. INTRODUCTION Magnetic fluid hyperthermia (MFH) is a promising approach

Krishnan, Kannan M.

215

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

E-print Network

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

Dunin-Borkowski, Rafal E.

216

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

217

Synthesis, characterization and magnetic properties of carbon nanotubes decorated with magnetic MIIFe2O4 nanoparticles  

NASA Astrophysics Data System (ADS)

In this study, a simple, efficient and reproducible microemulsion method was applied for the successful decoration of carbon nanotubes (CNTs) with magnetic MIIFe2O4 (M = Co, Ni, Cu, Zn) nanoparticles. The structure, composition and morphology of the prepared nanocomposite materials were characterized using X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). The magnetic properties were investigated by the vibrating sample magnetometer (VSM). The SEM results illustrated that large quantity of MIIFe2O4 nanoparticles were uniformly decorated around the circumference of CNTs and the sizes of the nanoparticles ranged from 15 to 20 nm. Magnetic hysteresis loop measurements revealed that all the MIIFe2O4/CNTs nanocomposites displayed ferromagnetic behavior at 300 K and can be manipulated using an external magnetic field. The CoFe2O4/CNTs nanocomposite showed maximum value of saturation magnetization which was 37.47 emu g-1. The as prepared MIIFe2O4/CNTs nanocomposites have many potential application in magnetically guided targeted drug delivery, clinical diagnosis, electrochemical biosensing, magnetic data storage and magnetic resonance imaging.

Ali, Syed Danish; Hussain, Syed Tajammul; Gilani, Syeda Rubina

2013-04-01

218

Magnetic properties of mixed cobalt–zinc ferrite nanoparticles  

Microsoft Academic Search

Solid solutions of nonstoichiometric mixed cobalt–zinc ferrite nanoparticles Co0.73yZn0.73(1?y)Fe2.18□0.09O4, were prepared in order to study their magnetic properties as a function of cobalt content y. The saturation magnetization changes with increasing y due to the various occupancies of cations in tetrahedral and octahedral sites and\\/or to an increase in the disorder of the ferrimagnetic structure. The cobalt content and particle

J. F. Hochepied; M. P. Pileni

2000-01-01

219

Magnetic properties of mixed cobalt-zinc ferrite nanoparticles  

Microsoft Academic Search

Solid solutions of nonstoichiometric mixed cobalt-zinc ferrite nanoparticles Co0.73yZn0.73(1-y)Fe2.18□0.09O4, were prepared in order to study their magnetic properties as a function of cobalt content y. The saturation magnetization changes with increasing y due to the various occupancies of cations in tetrahedral and octahedral sites and\\/or to an increase in the disorder of the ferrimagnetic structure. The cobalt content and particle

J. F. Hochepied; M. P. Pileni

2000-01-01

220

Inductive heat property of Fe 3O 4 nanoparticles in AC magnetic field for local hyperthermia  

Microsoft Academic Search

Magnetite (Fe3O4) nanoparticles with different magnetic properties were prepared by coprecipita-tion of Fe3 + and Fe2 + with aqueous NaOH solution. The inductive heat properties of Fe3O4 nanoparticles in an alternating current (AC) magnetic field were investigated for local hyperthermia. The maximum saturation magnetization Ms of Fe3O4 nanoparticles is 65.53 emu·g?1 under the optimum conditions of Fe3+\\/Fe2+ molar ratio at

Donglin ZHAO; Xianwei ZENG; Qisheng XIA; Jintian TANG

2006-01-01

221

Preparation and characterization of magnetic carboxymethyl chitosan\\/Fe3O4 composite nanoparticles  

Microsoft Academic Search

Monodisperse carboxymethyl chitosan-bound Fe3O4 magnetic nanoparticles can be potentially used as drug delivery carrier and a novel magnetic nano-adsorbent for the removal of pollutants from aqueous solutions. In this paper, the magnetic chitosan nanoparticles of about 20 nm were prepared by the carboxymethylation of chitosan and the followed binding on the surface of Fe3O4 nanoparticles which were prepared using a

Li-Min Zhou; Yi-Ping Wang; Qun-Wu Huang; Zhi-Rong Liue

2008-01-01

222

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

223

FEM numerical model study of heating in magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Electromagnetic heating of nanoparticles is complicated by the extremely short thermal relaxation time constants and difficulty of coupling sufficient power into the particles to achieve desired temperatures. Magnetic field heating by the hysteresis loop mechanism at frequencies between about 100 and 300 kHz has proven to be an effective mechanism in magnetic nanoparticles. Experiments at 2.45 GHz show that Fe3O4 magnetite nanoparticle dispersions in the range of 1012 to 1013 NP/mL also heat substantially at this frequency. An FEM numerical model study was undertaken to estimate the order of magnitude of volume power density, Qgen (W m-3) required to achieve significant heating in evenly dispersed and aggregated clusters of nanoparticles. The FEM models were computed using Comsol Multiphysics; consequently the models were confined to continuum formulations and did not include film nano-dimension heat transfer effects at the nanoparticle surface. As an example, the models indicate that for a single 36 nm diameter particle at an equivalent dispersion of 1013 NP/mL located within one control volume (1.0 x 10-19 m3) of a capillary vessel a power density in the neighborhood of 1017 (W m-3) is required to achieve a steady state particle temperature of 52°C - the total power coupled to the particle is 2.44 ?W. As a uniformly distributed particle cluster moves farther from the capillary the required power density decreases markedly. Finally, the tendency for particles in vivo to cluster together at separation distances much less than those of the uniform distribution further reduces the required power density.

Pearce, John A.; Cook, Jason R.; Hoopes, P. Jack; Giustini, Andrew

2011-03-01

224

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

225

Development of synthesis method for spinel ferrite magnetic nanoparticle and its superparamagnetic properties.  

E-print Network

??The magnetic spinel ferrite nanoparticle is exceptionally intriguing nanocrystal system due to the industrial importance of various technical applications and the scientific significance of studying… (more)

Han, Man Huon

2008-01-01

226

The role of eddy currents and nanoparticle size on AC magnetic fieldinduced reflow in solder/magnetic nanocomposites  

E-print Network

The role of eddy currents and nanoparticle size on AC magnetic field­induced reflow in solder://jap.aip.org/about/rights_and_permissions #12;The role of eddy currents and nanoparticle size on AC magnetic field­induced reflow in solder be derived from eddy current losses in Cu planes in the substrate board. Eddy current heating in Cu sheets

McHenry, Michael E.

227

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

228

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

PubMed

The purpose of this study was to develop a specific targeting magnetic nanoparticle probe for magnetic resonance imaging and therapy in the form of local hyperthermia. Carboxymethyl dextran-coated ultrasmall superparamagnetic iron oxide nanoparticles with carboxyl groups were coupled to cyclic arginine-glycine-aspartic peptides for integrin ?(v)?? targeting. The particle size, magnetic properties, heating effect, and stability of the arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide were measured. The arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide demonstrates excellent stability and fast magneto-temperature response. Magnetic resonance imaging signal intensity of Bcap37 cells incubated with arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide was significantly decreased compared with that incubated with plain ultrasmall superparamagnetic iron oxide. The preferential uptake of arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide by target cells was further confirmed by Prussian blue staining and confocal laser scanning microscopy. PMID:23796630

Zheng, S W; Huang, M; Hong, R Y; Deng, S M; Cheng, L F; Gao, B; Badami, D

2014-03-01

229

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

230

Iron Oxide Nanoparticles as a Drug Delivery Vehicle for MRI Monitored Magnetic Targeting of Brain Tumors  

PubMed Central

This study explored the possibility of utilizing iron oxide nanoparticles as a drug delivery vehicle for minimally invasive, MRI-monitored magnetic targeting of brain tumors. In vitro determined hydrodynamic diameter of ~100nm, saturation magnetization of 94 emu/g Fe and T2 relaxivity of 43 s?1mM?1 of the nanoparticles suggested their applicability for this purpose. In vivo effect of magnetic targeting on the extent and selectivity of nanoparticle accumulation in tumors of rats harboring orthotopic 9L-gliosarcomas was quantified with MRI. Animals were intravenously injected with nanoparticles (12 mg Fe/kg) under a magnetic field density of 0 T (control) or 0.4 T (experimental) applied for 30 minutes. MR images were acquired prior to administration of nanoparticles and immediately after magnetic targeting at 1 hour intervals for 4 hours. Image analysis revealed that magnetic targeting induced a 5-fold increase in the total glioma exposure to magnetic nanoparticles over non-targeted tumors (p=0.005) and a 3.6-fold enhancement in the target selectivity index of nanoparticle accumulation in glioma over the normal brain (p=0.025). In conclusion, accumulation of iron oxide nanoparticles in gliosarcomas can be significantly enhanced by magnetic targeting and successfully quantified by MR imaging. Hence, these nanoparticles appear to be a promising vehicle for glioma-targeted drug delivery. PMID:17964647

Chertok, Beata; Moffat, Bradford A.; David, Allan E.; Yu, Faquan; Bergemann, Christian; Ross, Brian D.; Yang, Victor C.

2009-01-01

231

CocoreAushell nanoparticles: evolution of magnetic properties in the displacement reaction  

E-print Network

protocols for the synthesis of phase-pure core­shell metal nanoparticles is an important problem in nanomaterials synthesis; the synthesis of Co-core Au-shell nanoparticles is described in this paper for the gold metal deposition on its surface. Hysteretic magnetic properties of nanoparticles depend critically

Krishnan, Kannan M.

232

Structure and magnetic properties of chemically prepared mixtures of crystalline and amorphous Fe(B) nanoparticles  

Microsoft Academic Search

A fine dispersion of crystalline and amorphous Fe(B) nanoparticles has been chemically prepared and its structural and magnetic properties compared to those of the corresponding single phase nanoparticles. The coercivity of the as-prepared dispersion was intermediate between that of the single phase crystalline and amorphous nanoparticles but less than expected from a simple rule of mixtures. Moreover, after annealing at

A. Gorea; T. F. Ekiert; E. A. Pearson; K. M. Unruh

2005-01-01

233

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

234

Structural And Magnetic Properties Of Ni-Zn Ferrite Nanoparticles  

NASA Astrophysics Data System (ADS)

Nickel zinc ferrite nanoparticles of the composition NixZn1-xFe2O4 (x = 0.1, 0.3, 0.5) have been synthesized by the chemical co-precipitation method. The samples were characterized by X-ray diffraction, TEM, EPR, DC magnetization and AC susceptibility measurements. The X-ray diffraction patterns confirm the synthesis of single crystalline phase of NixZn1-xFe2O4 (x = 0.1, 0.3, 0.5) nanoparticles. Lattice parameter decreases with the increase in nickel content. The magnetic measurements shows superparamagnetic nature of the samples for x = 0.1 and 0.3 whereas for x = 0.5 the material shows ferromagnetic nature. The saturation magnetization is low and increases with increase in nickel content. The superparamagnetic nature of the samples is supported by the EPR and ac susceptibility measurement studies. The blocking temperature increases with the nickel concentration. The changes in the magnetic properties have been explained by the redistribution of the cations on A and B sites.

Shahane, G. S.; Kumar, Ashok; Pant, R. P.; Lal, Krishan

2010-10-01

235

Temperature-induced phenomena in systems of magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticle ensembles have received a lot of attention, stemming in part from their current and potential applications in biomedicine and in the development of high-density magnetic storage media. Key to the functionality of these systems are microscopic structures and mechanisms that make them exhibit unique properties and behave differently from their bulk counterparts. We studied microscopic structures and processes that dictate macroscopic properties, behavior and functionality of magnetic nanoparticle ensembles. As the temperature T strongly influences the magnetic behavior of these systems, we studied temperature dependent magnetic properties using AC-susceptibility and DC-magnetization measurements carried out over a broad range of temperatures, between 3 and 300 K. We extracted structural information from X-ray diffraction (XRD) and direct imaging techniques and correlate it with magnetic properties, in an attempt at better understanding the microscopic structures and magnetic mechanisms responsible for the macroscopic magnetic behavior. We studied ensembles of magnetic nanoparticles: nickel ferrite immobilized in a solid matrix and cobalt ferrite immersed in carrier fluid respectively, in order to explore their potential use in biomedical applications and magnetic recording. For both NiFe2O4(NFO) and Co0.2Fe2.8O4 (CFO) relaxation mechanisms were determined. Structural properties and average particle sizes were derived from XRD, including synchrotron XRD, and direct imaging techniques such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Temperature dependent magnetic measurements, FC-ZFC DC magnetometry, as well as AC complex susceptibility measurements at frequencies between 10 and 10,000 Hz were carried out within the temperature range 3Kmagnetization and AC susceptibility measurements were performed using a Physical Property Measurement System (PPMS), which allows measurements in magnetic fields up to 9T and within a temperature range between 2 and 350 K. For NFO, besides the expected blocking of the superspin, observed at T1 ? 45 K, we found that the system undergoes a magnetic transition at T2 ? 6 K. For the latter, frequency- and temperature-resolved dynamic susceptibility data reveal characteristics that are unambiguously related to collective spin freezing: the relative variation (per frequency decade) of the in-phase-susceptibility peak temperature is ˜0.025, critical dynamics analysis yields an exponent zv = 9.6 and a zero-field freezing temperature TF = 5.8 K, and, in a magnetic field, TF (H) is excellently described by the de Almeida-Thouless line deltaT F infinity H2/3. Moreover, out-of-phase-susceptibility vs. temperature datasets collected at different frequencies collapse on a universal dynamic scaling curve. All these observations indicate the existence of a spin-glass-like surface layer that surrounds the superparamagnetic core and undergoes a transition to a frozen state upon cooling below 5.8 K. For the CFO ferrofluid, we used temperature- and frequency-resolved AC-susceptibility measurements to investigate its magnetic relaxation above the freezing point of the liquid carrier. Our data show that both the Neel and the Brown relaxation mechanisms are operative at temperatures in the vicinity of the out-of-phase (imaginary) susceptibility peak. We separate the contributions of the two mechanisms to the overall-relaxation time, and demonstrate that Brownian relaxation plays a dominant role at all temperatures within this high-dissipation regime.

Bhuiya, Abdul Wazed

236

Antimicrobial applications of water-dispersible magnetic nanoparticles in biomedicine.  

PubMed

The increasing morbidity and mortality of infectious diseases is an increasing concern. Despite the continuous development and synthesis of new antimicrobial drugs, microbial pathogens are exhibiting increased multi-drug resistance. Nanomaterials display unique and well-defined physical and chemical properties including a very high surface area to volume ratio, and new approaches for antimicrobial therapies have attempted to combine nanomaterials and current antimicrobial drugs. Magnetic nanoparticles (MNPs) are characterized by biocompatibility, biodegradation, and safety for human ingestion. Iron oxide nanoparticles have been approved for human use by the US Food and Drug Administration (FDA). For biomedicine applications, MNPs require surface modification to become water-soluble and be stable enough to resist the effects of proteins and salts in the physiological environment. MNPs can combine various substrata, such as biomolecules and nanomaterials to generate new antimicrobial agents which combine antibacterial, antiviral, and antifungal properties. This can be accomplished through a series of surface modification methods. Because MNPs have unique superparamagnetic characteristics, they can be controlled and recycled by an external magnetic field.In addition, the antimicrobial activity of MNPs-based nanocomposites is superior to that of metallic nanoparticles. This paper reviews the recent literature on the use of MNP-based nanomaterials in antimicrobial applications in biomedicine. Antimicrobial applications mainly focus on inhibiting and killing bacteria and fungi and viruses inactivation. The synthesis, surface modification, and characteristics related to MNPs will also be briefly addressed. PMID:24606505

Huang, Keng-Shiang; Shieh, Dar-Bin; Yeh, Chen-Sheng; Wu, Ping-Ching; Cheng, Fong-Yu

2014-01-01

237

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

238

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

239

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

240

Self-assembly of Superparamagnetic Nanoparticles with Permanent Magnetization  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles (MNPs) exhibit superparamagnetism when thermal fluctuations overcome the potential barrier for spin reversal set by magnetocrystalline anisotropy. The magnetic moment in such a material oscillates between the easy axes leading to zero net magnetization. Stable colloidal dispersions of MNPs exploit this state to prevent agglomeration. Self-assembly of MNPs presents an excellent bottom up nanofabrication technique due to the wide range of structures that can be formed. A stable dispersion of MNPs is an essential starting point for good control of the process. In this study we explore the theoretical basis for a self-assembled MNP structure with permanent magnetization starting from a dispersion of superparamangetic MNPs. Magnetostatic coupling of dipole moments enhance the potential barrier for magnetization reversals. We use X-Ray microCT and TEM to visualize the self-assembled structures. We use a stochastic form of the Landau-Lifshitz-Gilbert equation to simulate the magnetization dynamics in each MNP. Permanent magnetization in self-assembled structures generated in situ promise several significant applications such as targeted drug delivery, tissue engineering and novel soft composites.

Ghosh, Suvojit; Puri, Ishwar

2012-02-01

241

Chemical synthesis of hard magnetic SmCo nanoparticles Hongwang Zhang,a  

E-print Network

compositions and magnetism for high performance permanent magnetic applications. Developing magnetic and soft phases and have large coercivity and high magnetization.2­4 Among various methods developed for nanocomposite fabrication,5­10 self-assembly of hard and soft magnetic nanoparticles (NPs) has shown great

Liu, J. Ping

242

Visualization on the behavior of nanoparticles in magnetic fluids under the electric field  

NASA Astrophysics Data System (ADS)

The dielectric breakdown characteristics of magnetic fluids can be influenced by the magnetic nanoparticles included because their properties should be affected by the applied electric field. Based on measuring the dielectric breakdown voltage of magnetic fluids, we found that it is higher than that of the pure transformer oil in the case of the specific volume concentrations of magnetic nanoparticles. It is known from a numerical simulation that the conductive nanoparticles might behavior as electron scavengers in the electrically stressed magnetic fluids and change fast electrons into slowly negative charged nanoparticles for the electrical breakdown. In this study, we focus on the motion of magnetic nanoparticles in the fluids under the electric field applied by the visualization using a microchannel and an optical microscope.

Lee, W.-H.; Lee, J.-C.

2013-02-01

243

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

244

Superparamagnetic nanoparticle detection using second harmonic of magnetization response  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

245

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

246

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

247

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

248

Optimization of nanoparticle core size for magnetic particle imaging  

PubMed Central

Magnetic particle imaging (MPI) is a powerful new research and diagnostic imaging platform that is designed to image the amount and location of superparamagnetic nanoparticles in biological tissue. Here, we present mathematical modeling results that show how MPI sensitivity and spatial resolution both depend on the size of the nanoparticle core and its other physical properties, and how imaging performance can be effectively optimized through rational core design. Modeling is performed using the properties of magnetite cores, since these are readily produced with a controllable size that facilitates quantitative imaging. Results show that very low detection thresholds (of a few nanograms Fe3O4) and sub-millimeter spatial resolution are possible with MPI. PMID:19606261

Ferguson, R. Matthew; Minard, Kevin R.; Krishnan, Kannan M.

2009-01-01

249

The endocytic penetration mechanism of iron oxide magnetic nanoparticles with positively charged cover: a morphological approach.  

PubMed

In this study we present a morphological approach in observing the interaction of cationic magnetic nanoparticles with A-549 cells (human lung adenocarcinoma). Under our experimental conditions, nanoparticles easily penetrated cells and were observed in vivo, using bright light microscopy. In fixed cells, nanoparticles remained inside cells, showing quantity and distribution patterns similar to those in unfixed cells. The presence of nanoparticles did not affect cell viability or the morphologic parameters assessed. We determined the potential internalization mechanism of nanoparticles into cells using endocytosis inhibitors. The results suggest that nanoparticles used in this study penetrate A-549 cells mainly through a macropinocytosis process. PMID:20818493

Cañete, Magdalena; Soriano, Jorge; Villanueva, Angeles; Roca, Alejandro G; Veintemillas, Sabino; Serna, Carlos J; Miranda, Rodolfo; Del Puerto Morales, Maria

2010-10-01

250

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

E-print Network

Synthesis and characterization of Magnetic Nanoparticles and Their Reinforcement in Polyurethane intensive attention for their wide applications as biomaterials and magnetic storage materials. Polyurethane amounts were doped into polyurethane directly and composite films were made. Reinforced by the inorganic

Zheng, Yufeng

251

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

252

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

253

Ultrafast magnetization dynamics of cobalt nanoparticles and individual ferromagnetic dots  

NASA Astrophysics Data System (ADS)

The ultrafast magnetization dynamics of magnetic materials can be investigated using femtosecond laser pulses to perform femtosecond magneto-optical Kerr and Faraday measurements [1]. In this talk, we will focus on the magnetization dynamics of cobalt nanoparticles which are either ferromagnetic or super-paramagnetic at room temperature and on the dynamics of individual ferromagnetic dots. In the first case (Co nanoparticles), we will demonstrate that the magnetization dynamics preceding the fluctuations over the anisotropy energy barrier is coherent but exhibits a strongly damped precession [2]. These results, which have been obtained with a three dimensional analysis of the magnetization vector [3] will be discussed in the context of the N'eel-Brown models involving the gyromagnetic character of the magnetization. We will also examine the dynamics of self-organized supra-crystals of cobalt nanoparticles [4]. In the second case, we will present the ultrafast magnetization dynamics of individual ferromagnetic dots (CoPt3, Permalloy, Nickel) made either by e-beam lithography or induced optically on thin films deposited on sapphire and glass substrates. The technique employed is the magneto-optical pump probe imaging (MOPPI) which allows performing time resolved magneto-optical Kerr images with with spatial and temporal resolutions of 300 nm and 150 fs [5]. The study of the demagnetization of the dots for different laser intensities shows that it is possible to write and read ultrafast monodomains on thin films. [3pt] [1] E. Beaurepaire, J.-C. Merle, A. Daunois, J.-Y. Bigot Phys. Rev. Lett., 76, 4250 (1996) [0pt] [2] L.H.F. Andrade, A. Laraoui, M. Vomir, D. Muller, J.-P. Stoquert, C. Estournès, E. Beaurepaire, J.-Y. Bigot Phys. Rev. Lett. 97, 127401 (2006). [0pt] [3] M. Vomir, L. H.F. Andrade, L. Guidoni, E. Beaurepaire, J.-Y. Bigot Phys. Rev. Lett. 94, 237601 (2005). [0pt] [4] I. Lisiecki, V. Halt'e, C. Petit, M.-P. Pileni, J.-Y. Bigot Adv. Mater., 20, 4176 (2008). [0pt] [5] A. Laraoui, M. Albrecht, J.-Y. Bigot Optic. Letters 32, 936 (2007).

Bigot, Jean-Yves

2009-03-01

254

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

255

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

256

Studies of Fe 3O 4-chitosan nanoparticles prepared by co-precipitation under the magnetic field for lipase immobilization  

Microsoft Academic Search

A simple method was introduced to prepare magnetic Fe3O4-chitosan nanoparticles by co-precipitation with 0.45T static magnetic field via glutaraldehyde cross-linking reaction, and the nanoparticles were used to immobilize lipase. The influence of magnetic field on the properties of magnetic nanoparticles was studied by SEM, XRD and VSM. The results showed that no obvious difference of the nanoparticles structure was found,

Yong Liu; Shaoyi Jia; Qian Wu; Jingyu Ran; Wei Zhang; Songhai Wu

2011-01-01

257

Preparation and characterization of Saccharomyces cerevisiae alcohol dehydrogenase immobilized on magnetic nanoparticles  

Microsoft Academic Search

The covalently immobilized of Saccharomyces cerevisiae alcohol dehydrogenase (SCAD) to magnetic Fe3O4 nanoparticles via glutaraldehyde coupling reaction was studied. The magnetic Fe3O4 nanoparticles were prepared by hydrothermal method using H2O2 as an oxidizer. Functionalization of surface-modified magnetic particles was performed by the covalent binding of chitosan onto the surface. The amino functional group on the magnetic Fe3O4-chitosan particles surface and

Gui Yin Li; Ke Long Huang; Yu Ren Jiang; Dong Liang Yang; Ping Ding

2008-01-01

258

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

Microsoft Academic Search

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

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

1999-01-01

259

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

NASA Astrophysics Data System (ADS)

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

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

2007-04-01

260

FEM numerical model analysis of magnetic nanoparticle tumor heating experiments.  

PubMed

Iron oxide nanoparticles are currently under investigation as heating agents for hyperthermic treatment of tumors. Major determinants of effective heating include the biodistribution of magnetic materials, the minimum iron oxide loading required to achieve adequate heating, and practically achievable magnetic field strengths. These are inter-related criteria that ultimately determine the practicability of this approach to tumor treatment. Currently, we lack fundamental engineering design criteria that can be used in treatment planning and assessment. Coupling numerical models to experimental studies illuminate the underlying physical processes and can separate physical processes to determine their relative importance. Further, adding thermal damage and cell death process to the models provides valuable perspective on the likelihood of successful treatment. FEM numerical models were applied to increase the understanding of a carefully calibrated series of experiments in mouse mammary carcinoma. The numerical models results indicate that tumor loadings equivalent to approximately 1 mg of Fe3O4 per gram of tumor tissue are required to achieve adequate heating in magnetic field strengths of 34 kA/m (rms) at 160 kHz. Further, the models indicate that direct intratumoral injection of the nanoparticles results in between 1 and 20% uptake in the tissues. PMID:25571193

Pearce, John A; Petyk, Alicia A; Hoopes, P Jack

2014-08-01

261

Monodisperse magnetite nanoparticle tracers for in vivo magnetic particle imaging  

PubMed Central

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

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

2013-01-01

262

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

263

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

Microsoft Academic Search

Labeling of cells with nanoparticles for living detection is of interest to various biomedical applications. In this study,\\u000a novel fluorescent\\/magnetic nanoparticles were prepared and used in high-efficient cellular imaging. The nanoparticles coated\\u000a with the modified chitosan possessed a magnetic oxide core and a covalently attached fluorescent dye. We evaluated the feasibility\\u000a and efficiency in labeling cancer cells (SMMC-7721) with the

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

2009-01-01

264

Magnetic and fluorescent multifunctional chitosan nanoparticles as a smart drug delivery system  

Microsoft Academic Search

An innovative drug delivery system based on magnetic and fluorescent multifunctional chitosan nanoparticles was developed, which combined magnetic targeting, fluorescent imaging and stimulus-responsive drug release properties into one drug delivery system. Water-soluble superparamagnetic Fe3O4 nanoparticles, CdTe quantum dots (QDs) and pharmaceutical drugs were simultaneously incorporated into chitosan nanoparticles; cross-linking the composite particles with glutaraldehyde tailored their size, morphology, surface properties

Linlin Li; Dong Chen; Yanqi Zhang; Zhengtao Deng; Xiangling Ren; Xianwei Meng; Fangqiong Tang; Jun Ren; Lin Zhang

2007-01-01

265

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.

266

Optimization of nanoparticle core size for magnetic particle imaging R. Matthew Ferguson a  

E-print Network

Keywords: Magnetic nanoparticle Magnetic particle imaging Iron oxide nanoparticle Contrast agent Molecular quantitative imaging. Results show that very low detection thresholds (of a few nanograms Fe3O4) and sub MPI's unique detection scheme, which has been demonstrated in proof-of- principle experiments by its

Krishnan, Kannan M.

267

Magnetic and structural properties of ferrofluids based on Cobalt-Zinc ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Ferrofluids are colloidal systems composed of a single domain of magnetic nanoparticles with a mean diameter around 10 nm, dispersed in a liquid carrier. Magnetic Co(1-x)ZnxFe2O4 ferrite nanoparticles were prepared via co-precipitation method from aqueous salt solutions in an alkaline medium. The composition and structure of the samples were characterized through EDX and XRD, respectively. Transmission Electron Microscopy studies permitted determining nanoparticle size. Grain size of nanoparticle conglomerates was established via Atomic Force Microscopy. The magnetic behavior of ferrofluids was characterized by Vibrating Sample Magnetometer; and finally, a Magnetic Force Microscope was used to visualize the magnetic domains of nanoparticles. The mean size of the crystallite of nanoparticles determined by using the Scherrer approximation diminished when the Zn concentration increases. The size of the nanoparticles obtained by TEM is in good agreement with the crystallite size calculated from XRD measures. The magnetic properties investigated at room temperature presented super-paramagnetic behavior, determined by the shape of the hysteresis loop. Finally, our magnetic nanoparticles are considered a soft magnetic material.

Prieto, P.; Lopez, J.; Gomez, M. E.; Prado, J.; Caicedo, J.; Zambrano, G.; Gonzalez, L.; Esteve, J.

2012-02-01

268

The effect of thermal treatment on the magnetic properties of spinel ferrite nanoparticles in magnetic fluids  

NASA Astrophysics Data System (ADS)

Magnetic properties of ferrites are dependent on the crystalline structure and location of metal ions in the material. The most commonly used materials of nanoparticles in magnetic fluids are chemical stable spinel (2-3) ferrites. The preparation of ferrite nanoparticles for magnetic fluids synthesis needs a special technology. More commonly used is the wet chemical coprecipitation production technology of magnetic nanoparticles for MF. The ferrites synthesized by the wet chemical method have different magnetic characteristics if compared to the ferrites prepared by standard ceramic methods. In this paper, the physical properties of ultrafine complex spinel-type Fe _{2}Co _{0.3}Zn _{0.6}Ca _{0.1}O_{4}, Fe _{1.9}Cd _{0.1}Mn _{0.54}Zn _{0.46}O_{4}, Fe _{2}CoO_{4} and Fe _{2}Zn _{0.6}Mn _{0.3}Ca _{0.1}O_{4} ferrite particles and MF on its base, after their special thermal treatment, are studied. Tables 1, Figs 6, Refs 8.

Kronkalns, G.; Dreimane, A.; Maiorov, M. M.

2008-03-01

269

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

270

Magnetic nanoparticles as contrast agents in biomedical imaging: recent advances in iron- and manganese-based magnetic nanoparticles.  

PubMed

Improvements in diagnostic measures for biomedical applications have been investigated in various studies for better interpretations of biological abnormalities and several medical conditions. The use of imaging techniques, such as magnetic resonance imaging (MRI), is widespread and becoming a standard procedure for such specialized applications. A major avenue being studied in MRI is the use of magnetic nanoparticles (NPs) as contrast agents (CAs). Among various approaches, current research also incorporates use of superparamagnetic iron oxide NPs and manganese-based NPs with biocompatible coatings for improved stability and reduced biodegradation when exposed to a biological environment. In this review, recent advances with these types of magnetic NPs and their potential use as CAs in MRI are reported, as well as new insights into the selectivity and cellular transport mechanism that occurs following injection. PMID:24754519

Felton, Charlette; Karmakar, Alokita; Gartia, Yashraj; Ramidi, Punnamchandar; Biris, Alexandru S; Ghosh, Anindya

2014-05-01

271

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

272

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

273

Molecular imprinted magnetic nanoparticles for controlled delivery of mitomycin C.  

PubMed

Controlled drug delivery system is a technique which has considerable recent potential in the fields of pharmacy and medicine. Mitomycin C is commonly used drug in the treatment of superficial bladder and breast cancers. In the present study, mitomycin C-imprinted magnetic poly(hydroxyethyl methacrylate)-based nanoparticles (MIMNs) were prepared using surfactant free emulsion polymerization for controlled delivery of mitomycin C. The MIMNs were characterized by fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy, electron spin resonance, and elemental analysis. The average particle diameter of MIMNs was about 200 nm. PMID:23937455

Türkmen, Deniz; Bereli, Nilay; Çorman, M Emin; Shaikh, Huma; Akgöl, Sinan; Denizli, Adil

2014-10-01

274

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

275

Ultrafine metallic Fe nanoparticles: synthesis, structure and magnetism.  

PubMed

The results of the investigation of the structural and magnetic (static and dynamic) properties of an assembly of metallic Fe nanoparticles synthesized by an organometallic chemical method are described. These nanoparticles are embedded in a polymer, monodisperse, with a diameter below 2 nm, which corresponds to a number of around 200 atoms. The X-ray absorption near-edge structure and Mössbauer spectrum are characteristic of metallic Fe. The structural studies by wide angle X-ray scattering indicate an original polytetrahedral atomic arrangement similar to that of ?-Mn, characterized by a short-range order. The average magnetic moment per Fe atom is raised to 2.59 µ(B) (for comparison, bulk value of metallic Fe: 2.2 µ(B)). Even if the spontaneous magnetization decreases rapidly as compared to bulk materials, it remains enhanced even up to room temperature. The gyromagnetic ratio measured by ferromagnetic resonance is of the same order as that of bulk Fe, which allows us to conclude that the orbital and spin contributions increase at the same rate. A large magnetic anisotropy for metallic Fe has been measured up to (3.7 ± 1.0)·10(5) J/m(3). Precise analysis of the low temperature Mössbauer spectra, show a broad distribution of large hyperfine fields. The largest hyperfine fields display the largest isomer shifts. This indicates a progressive increase of the magnetic moment inside the particle from the core to the outer shell. The components corresponding to the large hyperfine fields with large isomer shifts are indeed characteristic of surface atoms. PMID:21977400

Margeat, Olivier; Respaud, Marc; Amiens, Catherine; Lecante, Pierre; Chaudret, Bruno

2010-01-01

276

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

277

Brain Tumor Targeting of Magnetic Nanoparticles for Potential Drug Delivery: Effect of Administration Route and Magnetic Field Topography  

PubMed Central

Our previous studies demonstrated feasibility of magnetically-mediated retention of iron-oxide nanoparticles in brain tumors after intravascular administration. The purpose of this study was to elucidate strategies for further improvement of this promising approach. In particular, we explored administration of the nanoparticles via a non-occluded carotid artery as a way to increase the passive exposure of tumor vasculature to nanoparticles for subsequent magnetic entrapment. However, aggregation of nanoparticles in the afferent vasculature interfered with tumor targeting. The magnetic setup employed in our experiments was found to generate a relatively uniform magnetic flux density over a broad range, exposing the region of the afferent vasculature to high magnetic force. To overcome this problem, the magnetic setup was modified with a 9-mm diameter cylindrical NdFeB magnet to exhibit steeper magnetic field topography. Six-fold reduction of the magnetic force at the injection site, achieved with this modification, alleviated the aggregation problem under the conditions of intact carotid blood flow. Using this setup, carotid administration was found to present 1.8-fold increase in nanoparticle accumulation in glioma compared to the intravenous route at 350 mT. This increase was found to be in reasonable agreement with the theoretically estimated 1.9-fold advantage of carotid administration, Rd. The developed approach is expected to present an even greater advantage when applied to drug-loaded nanoparticles exhibiting higher values of Rd. PMID:21763736

Chertok, Beata; David, Allan E.; Yang, Victor C.

2011-01-01

278

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

279

Synthesis and characterization of magnetic nanoparticles embedded in polyacrylonitrile nanofibers  

NASA Astrophysics Data System (ADS)

Nanomedicine is defined as the monitoring, repair, construction, and control of human biological systems at the molecular level using engineered nanodevices and nanostructures. Polyacrylonitrile (PAN) solution containing the iron oxide precursor iron (III) was electrospun and thermally treated to produce electrically conducting, magnetic carbon nanofiber mats with hierarchical pore structures. This paper discusses the synthesis of magnetite (Fe3O4) nanoparticles with mean crystallite size of 10 nm with polyacrylonitrile (PAN) as the protecting agent, creating nanofiber. The morphology and material properties of the resulting multifunctional nanofiber including the surface area were examined using various characterization techniques. Optical microscopy images show that uniform fibers were produced with a fiber diameter of ~600 nm, and this uniform fiber morphology is maintained after graphitization with a fiber diameter of ~330 nm. X-ray diffraction (XRD) studies reveal the size of Fe3O4 crystals. A combination of XRD and electron microscopy experiments reveals the formation of pores with graphitic nanoparticles in the walls as well as the formation of magnetite nanoparticles distributed throughout the fibers.

Munteanu, Daniel; Ion, Rodica-Mariana; Cocina, George-Costel

2010-11-01

280

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

PubMed

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

Lisjak, Darja; Jenuš, Petra; Mertelj, Alenka

2014-06-10

281

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

PubMed

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

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

2014-06-15

282

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

283

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

284

Potential of magnetic nanoparticles for targeted drug delivery.  

PubMed

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

285

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 10ppm 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

286

Chemisorption of cyanogen chloride by spinel ferrite magnetic nanoparticles.  

PubMed

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

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

2013-05-01

287

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

288

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

289

Nano-particle magnetism with a dispersion of particle sizes  

NASA Astrophysics Data System (ADS)

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

El-Hilo, M.

2012-11-01

290

MICROFLUIDIC MICROSYSTEM FOR MAGNETIC SENSING OF NANOPARTICLES WITH GIANT MAGNETO-IMPEDANCE TECHNOLOGY  

E-print Network

MICROFLUIDIC MICROSYSTEM FOR MAGNETIC SENSING OF NANOPARTICLES WITH GIANT MAGNETO field is sensed by the Giant Magneto-Impedance microwire sensor. The presence of the magnetic liquid between the point P and the magnetic liquid. In order to sense the field induced by the magnetic liquid

Boyer, Edmond

291

Off-axis electron holography of magnetic nanoparticles, nanostructures and devices  

E-print Network

Off-axis electron holography of magnetic nanoparticles, nanostructures and devices Rafal E. Dunin-axis electron holography is a powerful technique that can be used to characterize magnetic and electrostatic, are studied using electron holography to understand magnetic switching in out-of-plane magnetic fields

Dunin-Borkowski, Rafal E.

292

Crystallization process and magnetic properties of amorphous iron oxide nanoparticles  

NASA Astrophysics Data System (ADS)

This paper studied the crystallization process, phase transition and magnetic properties of amorphous iron oxide nanoparticles prepared by the microwave heating technique. Thermal analysis and magnetodynamics studies revealed many interesting aspects of the amorphous iron oxide nanoparticles. The as-prepared sample was amorphous. Crystallization of the maghemite ?-Fe2O3 (with an activation energy of 0.71 eV) and the hematite ?-Fe2O3 (with an activation energy of 0.97 eV) phase occurred at around 300 °C and 350 °C, respectively. A transition from the maghemite to the hematite occurred at 500 °C with an activation energy of 1.32 eV. A study of the temperature dependence of magnetization supported the crystallization and the phase transformation. Raman shift at 660 cm-1 and absorption band in the infrared spectra at 690 cm-1 showed the presence of disorder in the hematite phase on the nanoscale which is supposed to be the origin of the ferromagnetic behaviour of that antiferromagnetic phase.

Phu, N. D.; Ngo, D. T.; Hoang, L. H.; Luong, N. H.; Chau, N.; Hai, N. H.

2011-08-01

293

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

294

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

295

The influence of magnetic and physiological behaviour on the effectiveness of iron oxide nanoparticles for hyperthermia  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles are being developed for a wide range of biomedical applications. In particular, hyperthermia involves heating the magnetic nanoparticles through exposure to an alternating magnetic field. These materials offer the potential to selectively treat cancer by heating cancer tissue locally and at the cellular level. This may be a successful method if there are enough particles in a tumor possessing a sufficiently high specific absorption rate (SAR) to deposit heat quickly while minimizing thermal damage to surrounding tissue. High SAR magnetic nanoparticles have been developed and used in mouse models of cancer. The magnetic nanoparticles comprise iron oxide magnetic cores (mean core diameter of 50 nm) surrounded by a dextran layer shell for colloidal stability. In comparing two similar systems, the saturation magnetization is found to play a crucial role in determining the SAR, but is not the only factor of importance. (A difference in saturation magnetization of a factor of 1.5 yields a difference in SAR of a factor of 2.5 at 1080 Oe and 150 kHz.) Variations in the interactions due to differences in the dextran layer, as determined through neutron scattering, also play a role in the SAR. Once these nanoparticles are introduced into the tumor, their efficacy, with respect to tumor growth, is determined by the location of the nanoparticles within or near the tumor cells and the association of the nanoparticles with the delivered alternating magnetic field (AMF). This association (nanoparticle SAR and AMF) determines the amount of heat generated. In our setting, the heat generated and the time of heating (thermal dose) provides a tumor gross treatment response which correlates closely with that of conventional (non-nanoparticle) hyperthermia. This being said, it appears specific aspects of the nanoparticle hyperthermia cytopathology mechanism may be very different from that observed in conventional cancer treatment hyperthermia.

Dennis, C. L.; Jackson, A. J.; Borchers, J. A.; Ivkov, R.; Foreman, A. R.; Hoopes, P. J.; Strawbridge, R.; Pierce, Z.; Goerntiz, E.; Lau, J. W.; Gruettner, C.

2008-07-01

296

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

297

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

298

Preparation and coercivity and saturation magnetization dependence of inductive heating property of Fe 3O 4 nanoparticles in an alternating current magnetic field for localized hyperthermia  

Microsoft Academic Search

The magnetite (Fe3O4) nanoparticles with different magnetic properties were prepared by coprecipitation of Fe3+ and Fe2+ with an aqueous NaOH solution. The inductive heating property of Fe3O4 nanoparticles in an alternating current (ac) magnetic field was investigated. The potential of Fe3O4 nanoparticles was evaluated for localized hyperthermia treatment of cancers. The maximum saturation magnetization Ms of Fe3O4 nanoparticles was 65.53emug?1,

Dong-Lin Zhao; Xian-Wei Zeng; Qi-Sheng Xia; Jin-Tian Tang

2009-01-01

299

Quantification of magnetic nanoparticles by magnetorelaxometry and comparison to histology after magnetic drug targeting.  

PubMed

Magnetic nanoparticles can be used in medicine in vivo as contrast agents and as a drug carrier system for chemotherapeutics. Thus local cancer therapy is performed with Magnetic Drug Targeting (MDT) and allows a specific delivery of therapeutic agents to desired targets, i.e., tumors, by using a chemotherapeutic substance bound to magnetic nanoparticles and focused with an external magnetic field to the tumor after intraarterial application. Important for this therapeutic principle is the distribution of the particles in the whole organism and especially in the tumor. Therefore we used magnetorelaxometry to quantify ferrofluids delivered after MDT. Tissue samples of some mm3 volume of a VX2 squamous cell carcinoma were measured by magnetic relaxation and the amount of iron was determined using the original ferrofluid suspension as a reference. From this the distribution of the magnetic particles within the slice of tumor was reconstructed. Histological cross-sections of the respective tumor offer the opportunity to map quantitatively the particle distribution and the vascularisation in the targeted tumor on a microscopic scale. Our data show that the integral method magnetorelaxometry and microscopic histological methods can complete each other efficiently. PMID:17048540

Wiekhorst, F; Seliger, C; Jurgons, R; Steinhoff, U; Eberbeck, D; Trahms, L; Alexiou, C

2006-01-01

300

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

301

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

302

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

303

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

304

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

PubMed

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

305

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

306

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

307

Kinetics of adsorption of Saccharomyces cerevisiae mandelated dehydrogenase on magnetic Fe 3O 4–chitosan nanoparticles  

Microsoft Academic Search

The adsorption of Saccharomyces cerevisiae mandelated dehydrogenase (SCMD) protein on the surface-modified magnetic nanoparticles coated with chitosan was studied in a batch adsorption system. Functionalization of surface-modified magnetic particles was performed by the covalent binding of chitosan onto the surface of magnetic Fe3O4 nanoparticles. Characterization of these particles was carried out using FTIR spectra, transmission electron micrography (TEM), X-ray diffraction

Gui-Yin Li; Yu-Ren Jiang; Ke-Long Huang; Ping Ding; Li-Li Yao

2008-01-01

308

Removal of arsenate by cetyltrimethylammonium bromide modified magnetic nanoparticles.  

PubMed

Cetyltrimethylammonium bromide (CTAB) modified magnetic nanoparticles (Fe(3)O(4)@CTAB) were synthesized and used to remove arsenate from water. Fe(3)O(4)@CTAB was prepared by a modified simple co-precipitation process with cheap and environmental friendly iron salts and cationic surfactant CTAB. Powder X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infra-red spectroscopy were utilized to characterize the prepared adsorbent (Fe(3)O(4)@CTAB). Transmission electron microscopy (TEM) image showed that Fe(3)O(4)@CTAB particles were approximately spherical with the core size of 10 nm. With a saturation magnetization of 67.2 emu g(-1), the Fe(3)O(4)@CTAB nanoparticles could be easily separated from solutions with a simple magnetic process in very short time (within 5 min). Adsorption of arsenate on Fe(3)O(4)@CTAB reached equilibrium within 2 min at pH 6. Arsenate adsorption agreed well with pseudo-second order kinetic model and two-site Langmuir isotherm model with the arsenate adsorption capacity of 23.07 mg g(-l), which was twice greater than that of pure Fe(3)O(4). Arsenate removal rate was over 90% at a wide pH range from 3 to 9 and the removal of arsenate was not obviously affected by the presence of dissolved natural organic matter (up to 10 mg L(-1) as TOC) and competitive anions (sulfate, bicarbonate, and silicate up to 20 mg L(-1), and phosphate up to 5 mg L(-1)) in solutions. Fe(3)O(4)@CTAB could be regenerated in alkali solutions and more than 85% As(V) was removed even in fifth regeneration/reuse cycle. PMID:22703733

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

2012-08-15

309

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

310

Relaxation of biofunctionalized magnetic nanoparticles in ultra-low magnetic fields  

NASA Astrophysics Data System (ADS)

In this work, the spin-spin relaxation rate, 1/T2, and spin-lattice relaxation rate, 1/T1, of protons' spins induced by biofunctionalized magnetic nanoparticles and ferrofluids are investigated using a high-Tc superconducting quantum interference device-detected magnetometer in ultra-low fields. The biofunctionalized magnetic nanoparticles are the anti-human C-reactive protein (antiCRP) coated onto dextran-coated superparamagnetic iron oxides Fe3O4, which is labeled as Fe3O4-antiCRP. The ferrofluids are dextran-coated iron oxides. It was found that both 1/T2 and 1/T1 of protons in Fe3O4-antiCRP are enhanced by the presence of magnetic nanoparticles. Additionally, both the 1/T1 and 1/T2 of Fe3O4-antiCRP are close to that of ferrofluids, which are dextran-coated Fe3O4 dispersed in phosphate buffer saline. Characterizing the relaxation of Fe3O4-antiCRP can be useful for biomedical applications.

Yang, H. C.; Chiu, L. L.; Liao, S. H.; Chen, H. H.; Horng, H. E.; Liu, C. W.; Liu, C. I.; Chen, K. L.; Chen, M. J.; Wang, L. M.

2013-01-01

311

Formation of nanostructured magnetic films using layer-by-layer self-assembly of star polymers and magnetic nanoparticles.  

E-print Network

?? In this work, multi-layered thin film materials comprised of cobalt ferrite (CoFe2O4) magnetic nanoparticles and polystyrene amine-functionalized (PS-NH2) star polymers have been prepared on… (more)

Shah, Shimul

2011-01-01

312

Preparation and characterization of chemically functionalized silica-coated magnetic nanoparticles as a DNA separator.  

PubMed

The work describes a simple and convenient process for highly efficient and direct DNA separation with functionalized silica-coated magnetic nanoparticles. Iron oxide magnetic nanoparticles and silica-coated magnetic nanoparticles were prepared uniformly, and the silica coating thickness could be easily controlled in a range from 10 to 50 nm by changing the concentration of silica precursor (TEOS) including controlled magnetic strength and particle size. A change in the surface modification on the nanoparticles was introduced by aminosilanization to enhance the selective DNA separation resulting from electrostatic interaction. The efficiency of the DNA separation was explored via the function of the amino-group numbers, particle size, the amount of the nanoparticles used, and the concentration of NaCl salt. The DNA adsorption yields were high in terms of the amount of triamino-functionalized nanoparticles used, and the average particle size was 25 nm. The adsorption efficiency of aminofunctionalized nanoparticles was the 4-5 times (80-100%) higher compared to silica-coated nanoparticles only (10-20%). DNA desorption efficiency showed an optimum level of over 0.7 M of the NaCl concentration. To elucidate the agglomeration of nanoparticles after electrostatic DNA binding, the Guinier plots were calculated from small-angle X-ray diffractions in a comparison of the results of energy diffraction TEM and confocal laser scanning microscopy. Additionally, the direct separation of human genomic DNA was achieved from human saliva and whole blood with high efficiency. PMID:19099431

Kang, Kiho; Choi, Jinsub; Nam, Joong Hee; Lee, Sang Cheon; Kim, Kyung Ja; Lee, Sang-Won; Chang, Jeong Ho

2009-01-15

313

Magnetic resonance for in vitro medical diagnostics: superparamagnetic nanoparticle-based magnetic relaxation switches  

NASA Astrophysics Data System (ADS)

Advances in magnetic resonance (MR) miniaturization, along with nanoparticles and biotechnology, are extending MR applications in diagnostics to beyond the medical imaging regime. The principles behind magnetic resonance switch (MRSw) biosensors, as well as a summary of rapidly developing fields including MR miniaturization and MRSw demonstrations, are presented here. Due to the range of applications of MRSw biosensor tests and the breakthroughs in downsized instruments, continued development will enable the deployment of MRSw biosensors in a wide variety of settings and with potentially unlimited targets.

Demas, Vasiliki; Lowery, Thomas J.

2011-02-01

314

Influence of naturally occurring antioxidants on magnetic nanoparticles: risks, benefits, and possible therapeutic applications.  

PubMed

We have studied interaction of well known antioxidant L-ascorbic acid with magnetic nanoparticles containing insoluble Fe(III) in their core. In analogy with ferritin, mobilization of iron in the form of water soluble Fe(II) was observed, especially pronounced at higher temperatures. In the presence of hydrogen peroxide cytotoxic hydroxyl radicals are produced. These results suggest possible harmful effects of widely used magnetic nanoparticles as a MRI contrast agents in combination with overload of organism with ascorbic acid in some specific conditions, like fever of patient. On the other hand combination of magnetic nanoparticles and ascorbic acid may be used for a cancer therapy using alternating magnetic field for the release of Fe(II) via Néel relaxation of magnetic moment of used nanoparticles. We have further found that lipoic acid is an efficient antioxidant scavenging hydroxyl radicals produced by Fenton reaction from Fe(II). PMID:23479451

Durdík, Stefan; Vrbovská, Hanka; Olas, Adam; Babincová, Melánia

2013-06-01

315

Magnetic nanoparticle (MNP) enhanced biosensing by surface plasmon resonance (SPR) for portable devices  

NASA Astrophysics Data System (ADS)

The use of magnetic nanparticles in microfluidic systems is emerging and is receiving growing attention due to the synergistic advantages of microfluidics and magnetic nanoparticles. Biomagnetic separation techniques based on magnetic nanoparticles are becoming increasingly important with a wide range of possible applications. However, the separation products are difficult to be detected by general method due to the small size of MNPs. Here, we demonstrate magnetic nanoparticles can greatly enhance the signal of surface plasmon resonance spectroscopy (SPR). Features of MNPs-aptamer conjugates as a powerful amplification reagent for ultrasensitive immunoassay are explored for the first time. Our results confirm that MNPs is a powerful sandwich element and an excellent amplification reagent for SPR based sandwich immunoassay and SPR has a great potential for the detection of magnetic nanoparticles-based separation products.

Wang, Jianlong; Zhu, Zanzan; Munir, Ahsan; Zhou, H. Susan

2010-04-01

316

Orientation-dependent magnetic behavior in aligned nanoparticle arrays constructed by coaxial electrospinning  

NASA Astrophysics Data System (ADS)

A modified electrospinning process has been utilized to align magnetite (Fe3O4) nanoparticles inside highly oriented poly(ethylene oxide) nanofibers. The structural characterization of the fiber encapsulated nanoparticle arrays via electron microscopy has been detailed, and the magnetic behavior has been studied using vibrating sample magnetometry. The fiber encapsulated nanoparticle arrays exhibit orientation-dependent magnetic behavior with respect to the applied magnetic field. A strong anisotropy along orthogonal axes is obtained for aligned arrays and is manifested as a notable increase in the coercivity and remanence magnetization in the parallel field configuration. The magnetic behavior of isotropic fibers is also examined as a reference and no orientation dependence is observed. The results were found to corroborate theoretical predictions from the chain-of-spheres model. Such hybrid nanoparticle arrays may find relevance in applications requiring an orientation-dependent physical response and in the directional transfer of signals.

Sharma, Nikhil; Hassnain Jaffari, G.; Shah, S. Ismat; Pochan, Darrin J.

2010-02-01

317

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

318

Magnetic hydrogel nanocomposites and composite nanoparticles--a review of recent patented works.  

PubMed

Magnetic hydrogel nanocomposites and composite nanoparticles form a class of soft materials with remote controllable properties that have attracted great attention due to their potential use in diverse applications. These include medical applications such as controlled drug delivery, clinical imaging and cancer hyperthermia and ecological applications as well, such as wastewater treatment. The present review provides an overview of the patents disclosed and research work developed in the last decade on magnetic hydrogel nanocomposites and magnetic hydrogel composite nanoparticles envisaging the above mentioned applications. In this context, recent patented advances on chemical methods for the preparation of bulk hydrogel nanocomposites and composite nanoparticles will be reviewed. PMID:23763267

Daniel-da-Silva, Ana L; Carvalho, Rui S; Trindade, Tito

2013-06-01

319

In-vitro investigations of nanoparticle magnetic thermotherapy: adjuvant effects and comparison to conventional heating  

NASA Astrophysics Data System (ADS)

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

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

2007-02-01

320

Investigation of magnetically controlled water intake behavior of Iron Oxide Impregnated Superparamagnetic Casein Nanoparticles (IOICNPs).  

PubMed

Iron oxide impregnated casein nanoparticles (IOICNPs) were prepared by in-situ precipitation of iron oxide within the casin matrix. The resulting iron oxide impregnated casein nanoparticles (IOICNPs) were characterized by Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), Vibrating sample magnetometer (VSM) and Raman spectroscopy. The FTIR analysis confirmed the impregnation of iron oxide into the casein matrix whereas XPS analysis indicated for complete oxidation of iron (II) to iron(III) as evident from the presence of the observed representative peaks of iron oxide. The nanoparticles were allowed to swell in phosphate buffer saline (PBS) and the influence of factors such as chemical composition of nanoparticles, pH and temperature of the swelling bath, and applied magnetic field was investigated on the water intake capacity of the nanoparticles. The prepared nanoparticles showed potential to function as a nanocarrier for possible applications in magnetically targeted delivery of anticancer drugs. PMID:25277602

Singh, Anamika; Bajpai, Jaya; Bajpai, Anil

2014-10-01

321

Experimental and first-principles characterization of functionalized magnetic nanoparticles.  

PubMed

Magnetic iron oxide nanoparticles synthesized by coprecipitation and thermal decomposition yield largely monodisperse size distributions. The diameters of the coprecipitated particles measured by X-ray diffraction and transmission electron microscopy are between approximately 9 and 15 nm, whereas the diameters of thermally decomposed particles are in the range of 8 to 10 nm. Coprecipitated particles are indexed as magnetite-rich and thermally decomposed particles as maghemite-rich; however, both methods produce a mixture of magnetite and maghemite. Fourier transform IR spectra reveal that the nanoparticles are coated with at least two layers of oleic acid (OA) surfactant. The inner layer is postulated to be chemically adsorbed on the nanoparticle surface whereas the rest of the OA is physically adsorbed, as indicated by carboxyl O-H stretching modes above 3400 cm(-1). Differential thermal analysis (DTA) results indicate a double-stepped weight loss process, the lower-temperature step of which is assigned to condensation due to physically adsorbed or low-energy bonded OA moieties. Density functional calculations of Fe-O clusters, the inverse spinel cell, and isolated OA, as well as OA in bidentate linkage with ferrous and ferric atoms, suggest that the higher-temperature DTA stage could be further broken down into two regions: one in which condensation is due ferrous/ferrous- and/or ferrous/ferric-OA and the other due to condensation from ferrous/ferric- and ferric/ferric-OA complexes. The latter appear to form bonds with the OA carbonyl group of energy up to fivefold that of the bond formed by the ferrous/ferrous pairs. Molecular orbital populations indicate that such increased stability of the ferric/ferric pair is due to the contribution of the low-lying Fe(3+) t(2g) states into four bonding orbitals between -0.623 and -0.410 a.u. PMID:23649714

Antipas, Georgios S E; Statharas, Eleftherios; Tserotas, Philippos; Papadopoulos, Nikolaos; Hristoforou, E

2013-06-24

322

Enhanced magnetism in highly ordered magnetite nanoparticle-filled nanohole arrays.  

PubMed

A new approach to develop highly ordered magnetite (Fe3O4) nanoparticle-patterned nanohole arrays with desirable magnetic properties for a variety of technological applications is presented. In this work, the sub-100 nm nanohole arrays are successfully fabricated from a pre-ceramic polymer mold using spin-on nanoprinting (SNAP). These nanoholes a then filled with monodispersed, spherical Fe3O4 nanoparticles of about 10 nm diameter using a novel magnetic drag and drop procedure. The nanohole arrays filled with magnetic nanoparticles a imaged using magnetic force microscopy (MFM). Magnetometry and MFM measurements reveal room temperature ferromagnetism in the Fe3O4-filled nanohole arrays, while the as-synthesized Fe3O4 nanoparticles exhibit superparamagnetic behavior. As revealed by MFM measurements, the enhanced magnetism in the Fe3O4-filled nanohole arrays originates mainly from the enhanced magnetic dipole interactions of Fe3 O4 nanoparticles within the nanoholes and between adjacent nanoholes. Nanoparticle filled nanohole arrays can be highly beneficial in magnetic data storage and other applications such as microwave devices and biosensor arrays that require tunable and anisotropic magnetic properties. PMID:24706405

Duong, Binh; Khurshid, Hafsa; Gangopadhyay, Palash; Devkota, Jagannath; Stojak, Kristen; Srikanth, Hariharan; Tetard, Laurene; Norwood, Robert A; Peyghambarian, N; Phan, Manh-Huong; Thomas, Jayan

2014-07-01

323

Interfacial magnetic coupling between Fe nanoparticles in Fe–Ag granular alloys.  

PubMed

The role of the interface in mediating interparticle magnetic interactions has been analysed in Fe50Ag50 and Fe55Ag45 granular thin films deposited by the pulsed laser deposition technique (PLD). These samples are composed of crystalline bcc Fe (2–4 nm) nanoparticles and fcc Ag (10–12 nm) nanoparticles, separated by an amorphous Fe50Ag50 interface, occupying around 20% of the sample volume, as determined by x-ray diffraction (XRD), x-ray absorption spectroscopy (XAS), and high resolution transmission electron microscopy (HRTEM). Interfacial magnetic coupling between Fe nanoparticles is studied by dc magnetization and x-ray magnetic circular dichroism (XMCD) measurements at the Fe K and Ag L2,3 edges. This paper reveals that these thin films present two magnetic transitions, at low and high temperatures, which are strongly related to the magnetic state of the amorphous interface, which acts as a barrier for interparticle magnetic coupling. PMID:22166763

Alonso, J; Fdez-Gubieda, M L; Sarmiento, G; Chaboy, J; Boada, R; García Prieto, A; Haskel, D; Laguna-Marco, M A; Lang, J C; Meneghini, C; Fernández Barquín, L; Neisius, T; Orue, I

2012-01-20

324

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.

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

2014-01-01

325

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

326

Magnetic Properties of Zn1-xCoxO Nanoparticles.  

NASA Astrophysics Data System (ADS)

Zn1-xCoxO nanoparticles have been synthesized at various concentrations of Co2+ doping (0.005 ? x ? 0.15) by wet chemical method. Particle size was ranging from 34 - 45 nm. The magnetic moment increases from x = 0.005 and 0.01 sample to x = 0.04 sample drastically showing a value of magnetic moment as high as 8.54 ?B/Cations and then decreases for x = 0.09 and 0.15 values of Co2+ doping. There is almost paramagnetic behaviour for x = 0.005 and 0.01 Co2+ doped samples. The x = 0.04 sample shows ferromagnetic ordering. Ferromagnetic behaviour decreases for x = 0.09 and 0.15 samples as the antiferromagnetic interaction dominates at higher Co2+ doping concentrations. To probe the source of magnetism, we have undertaken photolu-minescence studies also which revealed the presence of oxygen and Zinc vacancies along with other defects.

Singh, Ningthoujam Surajkumar; Singh, Shougaijam Dorendrajit; Bandyopadhyay, Sujit Kumar

327

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

328

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

329

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

330

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

331

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

332

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

333

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

334

Facile synthesis, assembly, and immobilization of ordered arrays of monodisperse magnetic nanoparticles on silicon substrates.  

PubMed

This paper outlines the preparation of monodisperse MnFe(2)O(4) nanoparticles modified with omega-alkenyl moieties in a one-pot reaction, requiring no ligand-exchange step, followed by deposition of the resulting surfactant-coated nanoparticles onto a hydrogen-terminated silicon (111) wafer and covalent anchoring to the surface via UV-initiated bonding, creating a stable two-dimensional array of monodisperse magnetic nanoparticles. PMID:18931762

Leem, Gyu; Jamison, Andrew C; Zhang, Shishan; Litvinov, Dmitri; Lee, T Randall

2008-10-28

335

Magnetic carboxymethyl chitosan nanoparticles with immobilized metal ions for lysozyme adsorption  

Microsoft Academic Search

Nearly monodispersed and functional carboxymethyl chitosan nanoparticles (Fe3O4 (PEG+CM–CTS)) (about 15nm) which prepared by chemical coprecipitating were treated with Zn (II), Cu (II) and Fe (III) ions solutions to obtain immobilized metal affinity magnetic nanoparticles (IMAN) (short as Fe3O4 (PEG+CM–CTS) @ Zn (II), Fe3O4 (PEG+CM–CTS) @ Cu (II) and Fe3O4 (PEG+CM–CTS) @ Fe (III) nanoparticles). The presented synthetic technology is

Jun Sun; Shengqi Rao; Yujie Su; Rongrong Xu; Yanjun Yang

2011-01-01

336

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

337

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

338

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

PubMed

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

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

2012-05-01

339

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

340

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

341

Size-dependant heating rates of iron oxide nanoparticles for magnetic fluid hyperthermia  

E-print Network

Size-dependant heating rates of iron oxide nanoparticles for magnetic fluid hyperthermia Marcela in revised form 23 October 2008 Available online 24 December 2008 Keywords: Magnetic fluid hyperthermia in magnetic fluid hyperthermia (MFH). Possible approaches to increase heating rates of super- paramagnetic

Krishnan, Kannan M.

342

Mapping of the magnetic leakage fields from nanoparticles by Fresnel projection microscopy  

Microsoft Academic Search

The magnetic leakage fields from the poles of magnetic nanoparticles down to 105-106 spins, isolated or situated at the edges of clusters, are observed with Fresnel projection microscopy by the presence of interference fringes generated by the magnetic phase shifts in the imaging electron beam. The particle shapes and localization of fringes are imaged simultaneously with nanometer spatial resolution at

Vu Thien Binh; S. T. Purcell; V. Semet; F. Feschet

1998-01-01

343

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

Microsoft Academic Search

Magnetite nanoparticles with high self-heating capacity and low toxicity characteristics are a promising candidate for cancer hyperthermia treatment. In order to achieve minimum dosage to a patient, magnetic nanoparticles with high heating capacity are needed. In addition, the influence of physiological factors on the heat capacity of a material should be investigated in order to determine the feasibility. In this

Shihwei Chen; Chen-Li Chiang; Shuchen Hsieh

2010-01-01

344

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 to occupy tetrahedral sites, contrary to what occurs in bulk ferrites. The nanopowders display a semi constant is significantly higher for these nanoparticles than for bulk ferrites. Co1.8Fe1.2O4 hal-01053683

Paris-Sud XI, Université de

345

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 ...

346

Synthesis of magnetic nanocomposites and alloys from platinum-iron oxide core-shell nanoparticles  

SciTech Connect

This paper presents a systematic study on the generation of iron platinum-containing magnetic nanocomposites and alloys from Pt@Fe2O3 core-shell nanoparticle precursors. These core-shell nanoparticles were made using a sequential synthetic approach.

Teng, X.; Yang, H.

2005-06-22

347

Astroid curves of high-moment antiferromagnetic nanoparticles with tunable magnetic properties  

Microsoft Academic Search

We have determined astroids for high-moment antiferromagnetic nanoparticles (AN), which have been recently discovered and used in numerous biomedical applications. The astroid curves for such a system, which is a stack of two isolated disk-shaped ferromagnetic nanoparticles interacting antiferromagnetically, show the regions in the magnetic field plane where different numbers of minima associated with stable or metastable states may exist.

D. M. Forrester; E. Kovacs; K. E. Kürten; F. V. Kusmartsev

2009-01-01

348

Formulation and characterization of novel temperature sensitive polymer-coated magnetic nanoparticles.  

PubMed

The objective of this research was to develop novel polymer coated magnetic nanoparticles for controlled drug delivery applications. To form these novel nanoparticles, silane-coated magnetic nanoparticles (MNPs) were used as a template for a free radial polymerization of three monomers, N-isopropylacrylamide, acrylamide, and allylamine (NIPA-AAm-AH), on the surface of MNPs. Transmission electron microscope results indicated that the size of the NIPA-AAm-AH coated MNPs was approximately 100 nm. To investigate the chemical composition and chemical state of our nanoparticles, FTIR and XPS were used. Results from chemical analysis illustrated the presence of the constituent functional groups of the NIPA-AAm-AH coated MNPs. In addition, the magnetic properties of different layers on the MNPs, analyzed by SQUID, indicated a decrease in saturation magnetization after each layer of coating. The nanoparticles were successfully conjugated to fluorescent PEG to prolong their circulating half life. Furthermore, bovine serum albumin (BSA) was used in order to investigate the protein release profile of the nanoparticles as a function of the temperature. The protein release profile indicated that the NIPA-AAm-AH coated MNPs have a significantly higher percent release at 41 degrees C compared to those of 4 degrees C and 37 degrees C, which demonstrates their temperature sensitivity. In the future, the release profile of therapeutic drugs from nanoparticles at various temperatures and pHs as well as targeted capability of the synthesized nanoparticles for possible applications in controlled and targeted delivery will be investigated. PMID:21133151

Rahimi, Maham; Meletis, Efstathios I; You, Shaoxin; Nguyen, Kytai

2010-09-01

349

Determining the relaxivity values of protein cage-templated nanoparticles using magnetic resonance imaging.  

PubMed

The application of magnetic resonance imaging (MRI) is often limited by low magnetic relaxivity of currently used contrast agents. This problem can be addressed by developing more sensitive contrast agents by synthesizing new types of metal complex or metallic nanoparticles. Protein cage has been used as a template in biological synthesis of magnetic nanoparticles. The magnetic nanoparticle-protein cage composites have been reported to have high magnetic relaxivity, which implies their potential application as an MRI contrast agent. The magnetic relaxivity is determined by measuring longitudinal and transverse magnetic relaxivities of the potential agent. The commonly performed techniques are field-cycling NMR relaxometry (also known as variable field relaxometry or nuclear magnetic relaxation dispersion (NMRD) profiling) and in vitro or in vivo MRI relaxometry. Here, we describe techniques for the synthesis of nanoparticle-protein cage composite and determination of their magnetic relaxivities by in vitro MR image acquisition and data processing. In this method, longitudinal and transverse relaxivities are calculated by measuring relaxation rates of water hydrogen nuclei at different nanoparticle-protein cage composite concentrations. PMID:25358771

Sana, Barindra; Lim, Sierin

2015-01-01

350

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

351

Multilayered nanocoatings incorporating superparamagnetic nanoparticles for tracking of pancreatic islet transplants with magnetic resonance imaging.  

PubMed

A novel strategy for delivering functionalised superparamagnetic iron oxide nanoparticles to the outer surface of pancreatic islet grafts, using chemically modified polymeric nanolayers, has been developed for tracking of engrafted pancreatic islets by magnetic resonance imaging. PMID:23846395

Wang, Yang; Blanco-Andujar, Cristina; Zhi, Zheng-liang; So, Po-Wah; Thanh, Nguyen Thi Kim; Pickup, John C

2013-08-21

352

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

353

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

2014-11-19

354

Increased osteoblast density in the presence of novel calcium phosphate coated magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Bone diseases (including osteoporosis, osteoarthritis and bone cancer) are of great concern to the medical world. Drugs are available to treat such diseases, but often these drugs are not specifically targeted to the site of the disease and, thus, lack an immediate directed therapeutic effect. The optimal drug delivery system should enhance healthy bone growth with high specificity to the site of bone disease. It has been previously shown that magnetic nanoparticles can be directed in the presence of a magnetic field to any part of the body, allowing for site-specific drug delivery and possibly an immediate increase in bone density. The objective of the present study was to build off of this evidence and determine the density of osteoblasts (bone forming cells) in the presence of various uncoated and coated magnetic nanoparticles that could eventually be used in drug delivery applications. Results showed that some magnetic nanoparticles (specifically, ?-Fe2O3) significantly promoted osteoblast density (that is, cells per well) after 5 and 8 days of culture compared to controls (no particles). These magnetic nanoparticles were further coated with calcium phosphate (CaP; the main inorganic component of bone) to tailor them for treating various bone diseases. The coatings were conducted in the presence of either bovine serum albumin (BSA) or citric acid (CA) to reduce magnetic nanoparticle agglomeration, a common problem resulting from the use of nanoparticles which decreases their effectiveness. Results with these coatings showed that magnetic nanoparticles, specifically (?-Fe2O3), coated in the presence of BSA significantly increased osteoblast density compared to controls after 1 day. In this manner, this study provided unexpected evidence that CaP-coated ?-Fe2O3 magnetic nanoparticles increased osteoblast density (compared to no particles) and, thus, should be further studied to treat numerous bone diseases.

Pareta, Rajesh A.; Taylor, Erik; Webster, Thomas J.

2008-07-01

355

Preparation and properties of magnetic Fe 3O 4–chitosan nanoparticles  

Microsoft Academic Search

Magnetic Fe3O4–chitosan nanoparticles were prepared by the covalent binding of chitosan (CTS) onto the surface of magnetic Fe3O4 nanoparticles which were prepared by hydrothermal method using H2O2 as an oxidizer. Transmission electron microscopy (TEM) showed that Fe3O4 particles and Fe3O4–chitosan nanocomposites were regular sphere with a mean diameter of 23nm and 25nm, respectively. X-ray diffraction patterns (XRD) indicated that the

Gui-yin Li; Yu-ren Jiang; Ke-long Huang; Ping Ding; Jie Chen

2008-01-01

356

A newly developed Fe-doped calcium sulfide nanoparticles with magnetic property for cancer hyperthermia  

Microsoft Academic Search

In this study, a magnetic iron-doped calcium sulfide (Fe–CaS) nanoparticle was newly developed and studied for the purpose\\u000a of hyperthermia due to its promising magnetic property, adequate biodegradation rate, and relatively good biocompatibility.\\u000a Fe–CaS nanoparticles were synthesized by a wet chemical co-precipitation process with heat treatment in a N2 atmosphere, and were subsequently cooled in N2 and exposed to air

Steven Yueh-Hsiu Wu; Ching-Li Tseng; Feng-Huei Lin

2010-01-01

357

Study of magnetic and structural properties of ferrofluids based on cobalt-zinc ferrite nanoparticles  

Microsoft Academic Search

Ferrofluids are colloidal systems composed of a single domain of magnetic nanoparticles with a mean diameter around 30 nm, dispersed in a liquid carrier. Magnetic Co(1-x)ZnxFe2O4 (x=0.25, 0.50, 0.75) ferrite nanoparticles were prepared via co-precipitation method from aqueous salt solutions in an alkaline medium. The composition and structure of the samples were characterized through Energy Dispersive X-ray Spectroscopy and X-ray

J. López; L. F. González-Bahamón; J. Prado; J. C. Caicedo; G. Zambrano; M. E. Gómez; J. Esteve; P. Prieto

2012-01-01

358

Low-temperature magnetic property of polymer encapsulated gold nanoparticles  

NASA Astrophysics Data System (ADS)

Gold-polyaniline composite is reported by the polymerization of aniline hydrochloride monomer using HAuCl4 as the oxidant. HAuCl4 was dissolved in toluene using a phase-transfer catalyst, Aliquat 336. The oxidative polymerization of aniline hydrochloride leads to the formation of polyaniline with a diameter of <50 nm, while the reduction in auric acid results in the formation of gold nanoparticles with an average diameter ˜4 nm. The resultant composite material was characterized by means of different techniques, such as UV-vis, IR, and Raman spectroscopies, which offered the information about the chemical structure of polymer, whereas electron microscopy images provided information regarding the morphology of the composite material and the distribution of the metal particles in the polymer matrix. dc-magnetization measurements down to low temperatures (2 K) enabled the identification of a small, but field-independent paramagnetic behavior of the composite, and this is argued to originate from the charge transfer between the gold 5d-electron shell and the organic matrix. We believe that this material holds promise for both electronic and magnetic applications through suitable concentration levels of the metallic dopant.

Mallick, Kaushik; Witcomb, Michael; Erasmus, Rudolph; Strydom, André

2009-10-01

359

Infrared imaging for tumor detection using antibodies conjugated magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Thermography is a well known approach for cost effective early detection of concourse tumors. However, till now - more than 5 decades after its introduction - it is not considered as a primary tool for cancer early detection, mainly because its poor performance compared to other techniques. This work offers a new thermographic approach for tumor detection which is based on the use of antibody conjugated magnetic nanoparticles ("MNP") as a tumor specific marker. Wename this method "Thermal Beacon Thermography" ("TBT"), and it has the potential to provide considerable advantages over conventional thermographic approach. TBT approach is based on the fact that MNP are producing heat when subjected to an alternating magnetic field ("AMF"). Once these particles are injected to the patient blood stream, they specifically accumulate at the tumor site, providing a local heat source at the tumor that can be activated and deactivated by external control. This heat source can be used as a "thermal beacon" in order to detect and locate tumor by detecting temperature changes at the skin surface using an IR camera and comparing them to a set of pre-calculated numerical predictions. Experiments were conducted using an in vitro tissue model together with industrial inductive heating system and an IR camera. The results shows that this approach can specifically detect small tumor phantom (D=1.5mm) which was embedded below the surface of the tissue phantom.

Levy, Arie; Gannot, Israel

2008-04-01

360

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

NASA Astrophysics Data System (ADS)

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

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

2008-04-01

361

Study of magnetic and structural properties of ferrofluids based on cobalt-zinc ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Ferrofluids are colloidal systems composed of a single domain of magnetic nanoparticles with a mean diameter around 30 nm, dispersed in a liquid carrier. Magnetic Co(1-x)ZnxFe2O4 (x=0.25, 0.50, 0.75) ferrite nanoparticles were prepared via co-precipitation method from aqueous salt solutions in an alkaline medium. The composition and structure of the samples were characterized through Energy Dispersive X-ray Spectroscopy and X-ray diffraction, respectively. Transmission Electron Microscopy (TEM) studies permitted determining nanoparticle size; grain size of nanoparticle conglomerates was established via Atomic Force Microscopy. The magnetic behavior of ferrofluids was characterized by Vibrating Sample Magnetometer (VSM); and finally, a magnetic force microscope was used to visualize the magnetic domains of Co(1-x)ZnxFe2O4 nanoparticles. X-ray diffraction patterns of Co(1-x)ZnxFe2O4 show the presence of the most intense peak corresponding to the (311) crystallographic orientation of the spinel phase of CoFe2O4. Fourier Transform Infrared Spectroscopy confirmed the presence of the bonds associated to the spinel structures; particularly for ferrites. The mean size of the crystallite of nanoparticles determined from the full-width at half maximum of the strongest reflection of the (311) peak by using the Scherrer approximation diminished from (9.5±0.3) nm to (5.4±0.2) nm when the Zn concentration increases from 0.21 to 0.75. The size of the Co-Zn ferrite nanoparticles obtained by TEM is in good agreement with the crystallite size calculated from X-ray diffraction patterns, using Scherer's formula. The magnetic properties investigated with the aid of a VSM at room temperature presented super-paramagnetic behavior, determined by the shape of the hysteresis loop. In this study, we established that the coercive field of Co(1-x)ZnxFe2O4 magnetic nanoparticles, the crystal and nanoparticle sizes determined by X-ray Diffraction and TEM, respectively, decrease with the increase of the Zn at%. Finally, our magnetic nanoparticles are not very hard magnetic materials given that the hysteresis loop is small and for this reason Co(1-x)ZnxFe2O4 nanoparticles are considered as soft magnetic material.

López, J.; González-Bahamón, L. F.; Prado, J.; Caicedo, J. C.; Zambrano, G.; Gómez, M. E.; Esteve, J.; Prieto, P.

2012-02-01

362

Magneto-responsive nanocomposites: preparation and integration of magnetic nanoparticles into films, capsules, and gels.  

PubMed

This review reports on the latest developments in the field of magnetic nanocomposites, with a special focus on the potentials introduced by the incorporation of magnetic nanoparticles into polymer and supramolecular matrices. The general notions and the state of the art of nanocomposite materials are summarized and the results reported in the literature over the last decade on magnetically responsive films, capsules and gels are reviewed. The most promising concepts that have inspired the design of magneto-responsive nanocomposites are illustrated through remarkable examples where the integration of magnetic nanoparticles into organic architectures has successfully taken to the development of responsive multifunctional materials. PMID:24139510

Ridi, Francesca; Bonini, Massimo; Baglioni, Piero

2014-05-01

363

Magnetic chitosan nanoparticles: Studies on chitosan binding and adsorption of Co(II) ions  

Microsoft Academic Search

The magnetic chitosan nanoparticles of 13.5nm were prepared as a magnetic nano-adsorbent by the carboxymethylation of chitosan and the followed binding on the surface of Fe3O4 nanoparticles via carbodiimide activation. Their saturation magnetization, remanent magnetization, coercivity, and squareness were 62emu\\/g, 1.8emu\\/g, 6.0Oe, and 0.029, respectively, reflecting their superparamagnetic property. The binding reaction of carboxymethyl chitosan on the surface of Fe3O4

Yang-Chuang Chang; Song-Wen Chang; Dong-Hwang Chen

2006-01-01

364

Synthesis and magnetic properties of single-crystalline BaFe 12O 19 nanoparticles  

Microsoft Academic Search

Rod-like and platelet-like nanoparticles of simple-crystalline barium hexaferrite (BaFe12O19) have been synthesized by the molten salt method. Both particle size and morphology change with the reaction temperature and time. The easy magnetization direction (00l) of the BaFe12O19 nanoparticles has been observed directly by performing X-ray diffraction on powders aligned at 0.5T magnetic field. The magnetic properties of the BaFe12O19 magnet

Jiangying Yu; Shaolong Tang; Lin Zhai; Yangguang Shi; Youwei Du

2009-01-01

365

Competing magnetic interactions in nickel ferrite nanoparticle clusters: Role of magnetic interactions  

NASA Astrophysics Data System (ADS)

The magnetic behavior of nickel ferrite nanoparticles of different sizes was studied by annealing nickel ferrite powders at temperatures ranging from 300 to 900 °C. Transmission electron microscopy studies show that the average particle sizes change from ˜8 to ˜120 nm with increasing annealing temperatures. The x-ray diffraction patterns of the annealed samples reveal that a single phase is retained. Hysteresis measurements performed up to a field of 10 kOe show a tendency toward saturation. The saturation magnetization is found to increase with annealing temperature (particle size) with the magnetization tending toward the bulk value for powders annealed at 900 °C. Zero field cooled-field cooled measurements performed at 0.5 kOe indicate the presence of a superparamagnetic phase up to an annealing temperature of 700 °C with blocking temperatures in the range of 150-330 K. Numerical simulations are carried out using an interacting model of an array of single domain magnetic particles to explain the change in the magnetic behavior of the samples with annealing temperature and to estimate the anisotropy of the system. Our studies indicate that the observed magnetic behavior can be explained by the changes in the anisotropy of the system and the dominance of the short range interparticle exchange interactions over the long range dipolar interactions with increasing particle sizes. This change in the interaction profile is further confirmed by the Henkel plots for the particles annealed at different temperatures.

Malik, Rakesh; Annapoorni, S.; Lamba, Subhalakshmi; Sharma, Parmanand; Inoue, Akihisa

2008-09-01

366

Structures and magnetic properties of Nd1-xCaxFeO3 nanoparticles  

Microsoft Academic Search

Using a sol-gel method, Nd1-xCaxFeO3 nanoparticles with nearly the same average particle size and different Ca contents (x=0.1-0.5) and Nd0.9 Ca0.1 FeO3 nanoparticles with different particle sizes were prepared. Crystal structure and magnetic properties for the Nd1-xCaxFeO3 (x=0.1-0.5) nanoparticles have been investigated by x-ray diffraction and magnetic measurements. Both series samples have orthorhombic perovskite structure and the space group Pbnm.

Jiangong Li; Xinli Kou; Yong Qin; Haiying He

2002-01-01

367

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

PubMed Central

The present work demonstrates that Cy5.5 conjugated Fe3O4/SiO2 core/shell nanoparticles could allow us to control movement of human natural killer cells (NK-92MI) by an external magnetic field. Required concentration of the nanoparticles for the cell manipulation is as low as ~20 ?g Fe/mL. However, the relative ratio of the nanoparticles loaded NK-92MI cells infiltrated into the target tumor site is enhanced by 17-fold by applying magnetic field and their killing activity is still maintained as same as the NK-92MI cells without the nanoparticles. This approach allows us to open alternative clinical treatment with reduced toxicity of the nanoparticles and enhanced infiltration of immunology to the target site. PMID:22575830

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

2013-01-01

368

Magnetic Field Driven Alignment of Cobalt Nanoparticles and Directional Strengthening Effect in Polystyrene Matrix Nanocomposites  

NASA Astrophysics Data System (ADS)

Nanocomposite thin films of Polystyrene (PS) and PS-coated cobalt (Co) nanoparticles were prepared by solution-mixing and flow-coating. Ferromagnetic Co nanoparticles were either randomly dispersed or aligned in 1-D by applying a weak magnetic field during the flow-coating process. AFM and TEM images show nano-chain formation by self-assembly of the Co nanoparticles in the concentration range of 2-10 wt% relative to PS in the presence of magnetic field. The technique of Strain-Induced Elastic Buckling Instability for Mechanical Measurements (SIEBIMM) was employed to determine the elastic moduli of neat PS and PS / Co nanocomposite thin films, which were calculated from the buckling patterns generated by applying and releasing tensile stresses. Strengthening effect was found in nanocomposite thin films depending on the alignment direction of the dispersed Co nanoparticles. The effect of shape and concentration of nanoparticles on the elastic modulus of nanocomposite thin films will be discussed.

Yuan, Hongyi; Pyun, Jeffrey; Karim, Alamgir

2013-03-01

369

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

370

Intracellular performance of tailored nanoparticle tracers in magnetic particle imaging  

SciTech Connect

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

Arami, Hamed; Krishnan, Kannan M., E-mail: kannanmk@uw.edu [Department of Materials Science and Engineering, University of Washington, P.O. Box 352120, Seattle, Washington 98195-2120 (United States)

2014-05-07

371

Intracellular performance of tailored nanoparticle tracers in magnetic particle imaging  

NASA Astrophysics Data System (ADS)

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

Arami, Hamed; Krishnan, Kannan M.

2014-05-01

372

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 nanoparticles can be achieved in large quantities and at low cost. Over 1 kg (wet weight) of Zn-substituted magnetite (nominal composition of Zn0.6Fe2.4O4) has been recovered from 30 L fermentations. Transmission electron microscopy (TEM) was used to confirm that this mass produced extracellular magnetites exhibited good mono-dispersity. TEM results also showed a highly reproducible particle size and corroborated average crystallite size (ACS) of 13.1 0.8 nm determined through X-ray diffraction (N=7) at a 99 % confidence level. Based on scale-up experiments performed using a 35 L reactor, the increase in ACS reproducibility may be attributed to an increase of electron donor input, availability of divalent substitution metal ions and less ferrous ions in the case of substituted magnetite, increased reactor volume overcoming differences in each batch, or a combination of the above. While costs of commercial nanometer sized magnetite (25-50 nm) may cost $500/kg, microbial production is likely capable of producing 5-90 nm pure or substituted magnetites at a fraction of the cost of traditional chemical synthesis. While there are numerous approaches for the synthesis of nanoparticles, bacterial fermentation of magnetite or metal-substituted magnetite may represent an advantageous manufacturing technology with respect to yield, reproducibility and scalable synthesis with low costs at low energy input.

Moon, Ji Won [ORNL; Rawn, Claudia J [ORNL; Rondinone, Adam Justin [ORNL; Love, Lonnie J [ORNL; Roh, Yul [Chonnam National University, Gwangju; Lauf, Robert J [ORNL; Everett, Susan M [ORNL; Phelps, Tommy Joe [ORNL

2010-01-01

373

Observation of the dynamics of magnetic nanoparticles induced by a focused laser beam by using dark-field microscopy  

NASA Astrophysics Data System (ADS)

The dynamics of Fe3O4 magnetic nanoparticles under the irradiation of a tightly focused laser beam was investigated by using a high-intensity dark-field microscopy. A depletion region of magnetic nanoparticles was found at the center of the laser beam where the dissipative force (absorption and scattering forces) dominated the dynamics of the magnetic nanoparticles. In contrast, the dynamics of magnetic nanoparticles was dominated by thermal and mass diffusions at the edge of the laser beam where the dissipative force was negligible. In addition, the transient variation in the concentration of magnetic nanoparticles was characterized by recording the transient scattering light intensity. The coefficients of thermal diffusion, mass diffusion and the Soret effect for this kind of magnetic nanoparticles were successfully extracted by using this technique.

Deng, Hai-Dong; Li, Guang-Can; Li, Hai

2014-08-01

374

Single core-shell nanoparticle probes for non-invasive magnetic force microscopy.  

PubMed

We present an easy, fast and reliable method for the preparation of magnetic force microscopy (MFM) probes based on single Co nanoparticles (NPs). Due to their dipolar character, these magnetic probes open up a new approach for quantitative and non-invasive MFM measurements on the nanometer length scale. To guarantee long-term stability of these tips under ambient conditions, an ultrathin protecting Au shell was grown around the Co NPs through photochemical deposition. Single magnetic particles were firmly attached to standard silicon AFM tips using bifunctional self-assembling molecules. Such probes were tested on longitudinal magnetic recording media and compared to the results as recorded with conventional thin-film MFM tips. Easy data interpretation of the magnetic nanoparticle probes in a point dipole model is shown. Our nanoparticle tips provide excellent endurance for MFM recording, enable non-invasive probing while maintaining a high sensitivity, resolution, and reproducibility. PMID:24896585

Uhlig, Tino; Wiedwald, Ulf; Seidenstücker, Axel; Ziemann, Paul; Eng, Lukas M

2014-06-27

375

Thermoresponsive core-shell magnetic nanoparticles for combined modalities of cancer therapy  

NASA Astrophysics Data System (ADS)

Thermoresponsive polymer-coated magnetic nanoparticles loaded with anti-cancer drugs are of considerable interest for novel multi-modal cancer therapies. Such nanoparticles can be used for magnetic drug targeting followed by simultaneous hyperthermia and drug release. ?- Fe2O3 iron oxide magnetic nanoparticles (MNP) with average sizes of 14, 19 and 43 nm were synthesized by high temperature decomposition. Composite magnetic nanoparticles (CNP) of 43 nm MNP coated with the thermoresponsive polymer poly-n-isopropylacrylamide (PNIPAM) were prepared by dispersion polymerization of n-isopropylacrylamide monomer in the presence of the MNP. In vitro drug release of doxorubicin-(dox) loaded dehydrated CNP at temperatures below and above the lower critical solution temperature of PNIPAM (34 °C) revealed a weak dependence of drug release on swelling behavior. The particles displayed Fickian diffusion release kinetics; the maximum dox release at 42 °C after 101 h was 41%. In vitro simultaneous hyperthermia and drug release of therapeutically relevant quantities of dox was achieved, 14.7% of loaded dox was released in 47 min at hyperthermia temperatures. In vivo magnetic targeting of dox-loaded CNP to hepatocellular carcinoma (HCC) in a buffalo rat model was studied by magnetic resonance imaging (MRI) and histology. In summary, the good in vitro and in vivo performance of the doxorubicin-loaded thermoresponsive polymer-coated magnetic nanoparticles suggests considerable promise for applications in multi-modal treatment of cancer.

Purushotham, S.; Chang, P. E. J.; Rumpel, H.; Kee, I. H. C.; Ng, R. T. H.; Chow, P. K. H.; Tan, C. K.; Ramanujan, R. V.

2009-07-01

376

Synthesis and magnetic characterizations of La(1-x)Sr(x)MnO3 nanoparticles for biomedical applications.  

PubMed

The La(1-x)Sr(x)MnO3 (LSMO) nanoparticles have been synthesized by citric gel process followed by ball milling method. These nanoparticles demonstrated high crystalline quality. Nanoparticle size was further decreased by ball milling technique as observed by the field-emission scanning electron microscopic studies. The ball milled and silica coated LSMO nanoparticles show magnetic transition at about 370 K with a superparamagnetic properties. The ferromagnetic resonance (FMR) spectra analysis of LSMO nanoparticles shows large FMR linewidth due to the surface strain of the nanoparticles. Both magnetization and FMR studies demonstrate that the LSMO nanoparticles are highly anisotropic. The toxicity of the nanoparticles was studied for safe biomedical applications. Measurement of intracellular reactive oxygen species (ROS) and MTT assay results show that LSMO nanoparticles are relatively nontoxic and the toxicity is further reduced by SiO2 coating. These results are very important for applications in the field of biotechnology. PMID:21133070

Zhang, K; Holloway, T; Pradhan, J; Bahoura, M; Bah, R; Rakhimov, R R; Pradhan, A K; Prabakaran, R; Ramesh, G T

2010-09-01

377

Magnetic and fluorescent multifunctional chitosan nanoparticles as a smart drug delivery system  

NASA Astrophysics Data System (ADS)

An innovative drug delivery system based on magnetic and fluorescent multifunctional chitosan nanoparticles was developed, which combined magnetic targeting, fluorescent imaging and stimulus-responsive drug release properties into one drug delivery system. Water-soluble superparamagnetic Fe3O4 nanoparticles, CdTe quantum dots (QDs) and pharmaceutical drugs were simultaneously incorporated into chitosan nanoparticles; cross-linking the composite particles with glutaraldehyde tailored their size, morphology, surface properties and drug release behaviors. The system showed superparamagnetic and strong fluorescent properties, and was used as a controlled drug release vehicle, which showed pH-sensitive drug release over a long time. The composite magnetic and fluorescent chitosan nanoparticles are potential candidates as a smart drug delivery system.

Li, Linlin; Chen, Dong; Zhang, Yanqi; Deng, Zhengtao; Ren, Xiangling; Meng, Xianwei; Tang, Fangqiong; Ren, Jun; Zhang, Lin

2007-10-01

378

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

NASA Astrophysics Data System (ADS)

In the present work is reported the use of the biopolymer chitosan as template for the preparation of magnetite and magnetite/silver core/shell nanoparticles systems, following a two step procedure of magnetite nanoparticles in situ precipitation and subsequent silver ions reduction. The crystalline and morphological characteristics of both magnetite and magnetite/silver core/shell nanoparticles systems were analyzed by high resolution transmission electron microscopy (HRTEM) and nanobeam diffraction patterns (NBD). The results of these studies corroborate the core/shell morphology and the crystalline structure of the magnetite core and the silver shell. Moreover, magnetization temperature dependent, M( T), measurements show an unusual diluted magnetic behavior attributed to the dilution of the magnetic ordering in the magnetite and magnetite/silver core/shell nanoparticles systems.

Garza-Navarro, Marco; Torres-Castro, Alejandro; González, Virgilio; Ortiz, Ubaldo; De la Rosa, Elder

2010-01-01

379

Effect of nanoparticles on the magnetic properties of Mn-Zn soft ferrite  

NASA Astrophysics Data System (ADS)

In this paper, the effect of nanostructures on the magnetic properties like the specific saturation magnetization ( ?S) and the coercivity ( HC) for Mn 0.4Zn 0.6Fe 2O 4 ferrite prepared by the co-precipitation method has been presented. We have shown by means of X-ray diffraction that the resulting ferrite is made up of nanoparticles, and that the average size of these nanoparticles calculated with the Scherrer formula depends upon the sintering temperature. When the sintering temperature is increased from 500 to 900 °C, the average nanoparticle diameter varies from 19.3 to 36.4 nm. The nanoparticle phase is further confirmed by scanning electron microscopy (SEM). Both results are found to be in good agreement. The magnetic properties are explained on the basis of the single-domain and multi-domain theory.

Mathur, Preeti; Thakur, Atul; Singh, M.

380

Development of heparin-coated magnetic nanoparticles for targeted drug delivery applications  

NASA Astrophysics Data System (ADS)

We have designed a potential drug delivery system by combining low-molecular-weight heparin to iron oxide magnetic nanoparticles with an average size of 20 nm. The particles were synthesized by the NaBH4 reduction of FeCl2 and then coated with poly-L-lysine. Heparin was noncovalently conjugated on these nanoparticles via the interactions between the negatively charged sulfate and carboxylate groups of heparin and the positively charged amine group of poly-L-lysine. The nanoparticles were examined by using transmission electron microscopy, x-ray diffraction, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, and zeta potential measurements. The data provide direct evidence that the heparin was immobilized at the surface of poly-L-lysine-coated iron oxide nanoparticles. Magnetic measurements revealed the particles are ferromagnetic with a saturation magnetization of 31 emu/g.

Khurshid, H.; Kim, S. H.; Bonder, M. J.; Colak, L.; Ali, Bakhtyar; Shah, S. I.; Kiick, K. L.; Hadjipanayis, G. C.

2009-04-01

381

Synthesis and characterization of tat-mediated O-CMC magnetic nanoparticles having anticancer function  

NASA Astrophysics Data System (ADS)

This paper describes a new formulation of magnetic nanoparticles coated by a novel polymer matrix—O-carboxylmethylated chitosan (O-CMC) as drug/gene carrier. The O-CMC magnetic nanoparticles were derivatized with a peptide sequence from the HIV-tat protein to improve the translocational property and cellar uptake of the nanoparticles. To evaluate the O-MNPs-tat as drug carriers, MTX was incorporated as a model drug and MTX-loaded O-MNPs-tat with an average diameter of 45-60 nm were prepared and characterized by TEM, AFM and VSM. The cytotoxicity of MTX-loaded O-MNPs-tat was investigated with U-937 tumor cells. The results showed that the MTX-loaded O-MNPs-tat retained significant antitumor toxicity; additionally, sustained release of MTX from O-CMC nanoparticles was observed in vitro, suggesting that the tat-O-MNPs could be a novel magnetic targeting carrier.

Zhao, Aijie; Yao, Peng; Kang, Chunshang; Yuan, Xubo; Chang, Jin; Pu, Peiyu

2005-08-01

382

Magnetic resonance of the NiFe2O4 nanoparticles in the gigahertz range  

PubMed Central

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

2013-01-01

383

Three-dimensional magnetic field determination in magnetic nanoparticles using iterative reconstruction techniques  

NASA Astrophysics Data System (ADS)

Improving processing methods have consistently decreased the length scales of many magnetic devices. Methods to quantify the physical and magnetic domain structure of magnetic materials are needed to optimize their performance. However, magnetic characterization methods typically only measure one or two components of the magnetic properties. For instance, Lorentz microscopy is used to construct a two-dimensional projection of the magnetic induction. The vector field electron tomography (VFET) method uses Lorentz microscopy and tomography techniques to reconstruct the three-dimensional magnetic induction and magnetic vector potential of a sample. However, these reconstructions suffer from errors due to factors such as missing wedge information due to the nature of the samples and the physical constraints of the transmission electron microscope. Iterative tomographic techniques and the use of prior knowledge have been used in the literature to compensate for missing wedge data. In this work, we present several tools to construct iterative VFET (IVFET) algorithms. The iterative tomography algorithms Simultaneous Iterative Reconstruction Technique (SIRT), Discrete Algebraic Reconstruction Technique (DART), and Model-Based Iterative Reconstruction (MBIR) are summarized, and their relative merits are discussed. A novel approach to solving the Transport of Intensity Equation (TIE) that incorporates phase separation is presented, along with a comparison to the standard method. A model for simulating VFET images of a chain of nanoparticles and tomographic reconstructions using the model are shown. A spherical voxel forward projection model that can be used to update a single voxel of a VFET reconstruction and its projections is presented as a method for updating the reconstruction during iterative tomography.

Humphrey, Emma Margaret

384

Tuning Magnetic Properties of Magnetic Recording Media Cobalt Ferrite NanoParticles by CoPrecipitation Method  

Microsoft Academic Search

Magnetic nano-particles of cobalt ferrite were prepared using co-precipitation method. X-ray diffraction, transmission electron microscope and Raman analysis have confirmed that the formation of cobalt ferrite nano-particles with different particle size depending on the rate of reaction and nucleation. X-ray photoelectron spectrometer analysis indicates that the reaction rate have little influence on the cation distribution in the tetrahedral and octahedral

Shu Chang; Qiao Haoxue

2009-01-01

385

Cancer therapy with drug loaded magnetic nanoparticles—magnetic drug targeting  

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

386

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

PubMed Central

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

2012-01-01

387

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

SciTech Connect

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

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

2009-10-15

388

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

389

Carboxymethyl starch-chitosan-coated iron oxide magnetic nanoparticles for controlled delivery of isoniazid.  

PubMed

Abstract Context: The coating material of magnetic nanoparticles plays a great role in drug delivery application. The coatings not only increase the stability of the nanoparticles but also improve the drug release pattern, biocompatibility and mucoadhesivity. Objective: Montmorillonite (MMT) containing magnetic iron oxide nanoparticles coated with polyelectrolyte complex (PEC) of carboxymethyl starch-chitosan were prepared for controlled release applications. Method: The PEC-coated nanoparticles were characterised by Fourier Transmission Infra-red spectroscopy and X-ray diffraction, scanning electron microscope, transmission electron microscope, and dynamic light scattering. Cytotoxicity study was performed by MTT assay analysis. Mucoadhesivity test was performed by using in vitro wash off and ex vivo method. Result: The coating of PEC showed good stability, biocompatibility and mucoadhesivity of the iron oxide magnetic nanoparticles. MMT addition enhanced the swelling, drug loading and release and also the cytotoxicity and mucoadhesivity of the nanoparticles. Conclusion: This study revealed that the MMT incorporated PEC of CMS-CS can be effectively used for coating of iron oxide nanoparticles. PMID:25090597

Saikia, Chinmayee; Hussain, Anowar; Ramteke, Anand; Sharma, Hemanta K; Maji, Tarun K

2014-08-01

390

Separation and measurement of silver nanoparticles and silver ions using magnetic particles.  

PubMed

The recent surge in consumer products and applications using metallic nanoparticles has increased the possibility of human or ecosystem exposure due to unintentional release into the environment. To protect consumer health and the environment, there is an urgent need to develop tools that can characterize and quantify these materials at low concentrations and in complex matrices. In this study, magnetic nanoparticles coated with either dopamine or glutathione were used to develop a new, simple and reliable method for the separation/pre-concentration of trace amounts of silver nanoparticles followed by their quantification using inductively coupled plasma mass spectrometry (ICP-MS). The structurally modified magnetic particles were able to capture trace amounts of silver nanoparticles (~2 ppb) and concentrate (up to 250 times) the particles for analysis with ICP-MS. Under laboratory conditions, recovery of silver nanoparticles was >99%. More importantly, the magnetic particles selectively captured silver nanoparticles in a mixture containing both nano-particulate and ionic silver. This unique feature addresses the challenges of separation and quantification of silver nanoparticles in addition to the total silver in environmental samples. Spiking experiments showed recoveries higher than 97% for tap water and both fresh and saline surface water. PMID:24295749

Mwilu, Samuel K; Siska, Emily; Baig, R B Nasir; Varma, Rajender S; Heithmar, Ed; Rogers, Kim R

2014-02-15

391

Morphological effect of oscillating magnetic nanoparticles in killing tumor cells.  

PubMed

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

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

2014-01-01

392

Spectroscopic AC susceptibility imaging (sASI) of magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

This study demonstrates a method for alternating current (AC) susceptibility imaging (ASI) of magnetic nanoparticles (mNPs) using low cost instrumentation. The ASI method uses AC magnetic susceptibility measurements to create tomographic images using an array of drive coils, compensation coils and fluxgate magnetometers. Using a spectroscopic approach in conjunction with ASI, a series of tomographic images can be created for each frequency measurement set and is termed sASI. The advantage of sASI is that mNPs can be simultaneously characterized and imaged in a biological medium. System calibration was performed by fitting the in-phase and out-of-phase susceptibility measurements of an mNP sample with a hydrodynamic diameter of 100 nm to a Brownian relaxation model (R2=0.96). Samples of mNPs with core diameters of 10 and 40 nm and a sample of 100 nm hydrodynamic diameter were prepared in 0.5 ml tubes. Three mNP samples were arranged in a randomized array and then scanned using sASI with six frequencies between 425 and 925 Hz. The sASI scans showed the location and quantity of the mNP samples (R2=0.97). Biological compatibility of the sASI method was demonstrated by scanning mNPs that were injected into a pork sausage. The mNP response in the biological medium was found to correlate with a calibration sample (R2=0.97, p<0.001). These results demonstrate the concept of ASI and advantages of sASI.

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

2015-02-01

393

Spectroscopic AC Susceptibility Imaging (sASI) of Magnetic Nanoparticles.  

PubMed

This study demonstrates a method for alternating current (AC) susceptibility imaging (ASI) of magnetic nanoparticles (mNPs) using low cost instrumentation. The ASI method uses AC magnetic susceptibility measurement to create tomographic images using an array of drive coils, compensation coils and fluxgate magnetometers. Using a spectroscopic approach in conjunction with ASI, a series of tomographic images can be created for each frequency measurement and is termed sASI. The advantage of sASI is that mNPs can be simultaneously characterized and imaged in a biological medium. System calibration was performed by fitting the in-phase and out-of-phase susceptibility measurements of an mNP sample with a hydrodynamic diameter of 100 nm to a Brownian relaxation model (R(2) = 0.96). Samples of mNPs with core diameters of 10 and 40 nm and a sample of 100 nm hydrodynamic diameter were prepared in 0.5 ml tubes. Three mNP samples were arranged in a randomized array and then scanned using sASI with six frequencies between 425 and 925 Hz. The sASI scans showed the location and quantity of the mNP samples (R(2) = 0.97). Biological compatibility of the sASI method was demonstrated by scanning mNPs that were injected into a pork sausage. The mNP response in the biological medium was found to correlate with a calibration sample (R(2) = 0.97, p <0.001). These results demonstrate the concept of ASI and advantages of sASI. PMID:25477704

Ficko, Bradley W; Nadar, Priyanka M; Diamond, Solomon G

2015-02-01

394

Biofunctionalized Magnetic Nanoparticles for Specifically Detecting Biomarkers of Alzheimer’s Disease in Vitro  

PubMed Central

Magnetic nanoparticles biofunctionalized with antibodies against ?-amyloid-40 (A?-40) and A?-42, which are promising biomarkers related to Alzheimer’s disease (AD), were synthesized. We characterized the size distribution, saturated magnetizations, and stability of the magnetic nanoparticles conjugated with anti-A? antibody. In combination with immunomagnetic reduction technology, it is demonstrated such biofunctionalized magnetic nanoparticles are able to label A?s specifically. The ultralow-detection limits of assaying A?s in vitro using the magnetic nanoparticles via immunomagnetic reduction are determined to a concentration of ?10 ppt (10 pg/mL). Further, immunomagnetic reduction signals of A?-40 and A?-42 in human plasma from normal samples and AD patients were analyzed, and the results showed a significant difference between these two groups. These results show the feasibility of using magnetic nanoparticles with A?s as reagents for assaying low-concentration A?s through immunomagnetic reduction, and also provide a promising new method for early diagnosis of Alzheimer’s disease from human blood plasma. PMID:22860173

2011-01-01

395

Doxorubicin-loaded mesoporous magnetic nanoparticles to induce apoptosis in breast cancer cells.  

PubMed

Selective targeting of chemotherapeutic drugs toward the cancer cells overcomes the limitations involved in chemotherapy. Ideally, targeted delivery system holds great potential in cancer therapy due to specific release of drug in the cancer tissues. In this regard, DOX-loaded chitosan coated mesoporous magnetic nanoparticles (DOX-CMMN) were prepared and evaluated for its physicochemical and biological characteristics. Nanosized magnetic nanoparticles were observed with a high loading capacity for DOX. The drug-loaded nanoparticles exhibited a controlled and sustained release of drug without any burst release phenomenon. The DOX-DMMN showed a concentration-dependent cell proliferation inhibitory action against breast cancer cells. The blank nanoparticles showed excellent biocompatibility with cell viability >85% at the maximum tested concentration. Our results showed that chitosan coated magnetic system has high potential for breast cancer targeting under an alternating current magnetic field (ACMF). The present study showed that magnetic nanoparticles can be targeted to tumor cells under the presence of oscillating magnetic field. The combined effect of chemotherapy and thermotherapy can have a promising clinical potential for the treatment of breast cancer. PMID:25661382

Zou, Yan; Liu, Pin; Liu, Chuan-He; Zhi, Xu-Ting

2015-02-01

396

Polymer-assisted iron oxide magnetic nanoparticle immobilized keratinase  

NASA Astrophysics Data System (ADS)

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

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

2009-06-01

397

Polymer-assisted iron oxide magnetic nanoparticle immobilized keratinase.  

PubMed

Nanotechnology holds the prospect for avant-garde changes to improve the performance of materials in various sectors. The domain of enzyme biotechnology is no exception. Immobilization of industrially important enzymes onto nanomaterials, with improved performance, would pave the way to myriad application-based commercialization. Keratinase produced by Bacillus subtilis was immobilized onto poly(ethylene glycol)-supported Fe3O4 superparamagnetic nanoparticles. The optimization process showed that the highest enzyme activity was noted when immobilized onto cyanamide-activated PEG-assisted MNP prepared under conditions of 25 degrees C and pH 7.2 of the reaction mixture before addition of H2O2 (3% w/w), 2% (w/v) PEG(6000) and 0.062:1 molar ratio of PEG to FeCl2 x 4H2O. Further statistical optimization using response surface methodology yielded an R2 value that could explain more than 94% of the sample variations. Along with the magnetization studies, the immobilization of the enzyme onto the PEG-assisted MNP was characterized by UV, XRD, FTIR and TEM. The immobilization process had resulted in an almost fourfold increase in the enzyme activity over the free enzyme. Furthermore, the immobilized enzyme exhibited a significant thermostability, storage stability and recyclability. The leather-industry-oriented application of the immobilized enzyme was tested for the dehairing of goat-skin. PMID:19433867

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

2009-06-01

398

Magnetic multicomponent nanoparticles CuxMn1-xFe2O4 for biomedical applications  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles (NPs) are increasingly important in many biomedical applications, such as drug delivery, hyperthermia, and magnetic resonance imaging (MRI) contrast enhancement. In this multicomponent nanoparticles CuxMn1-xFe2O4 (CuMnF), x= 0, 0.6, 1, were prepared by hydrothermal synthesis, sol-gel and solid state methods. To build the most effective magnetic nanoparticle systems for various biomedical applications, particle characteristics including size, surface chemistry, magnetic properties and toxicity have to be fully investigated. In this work, effects of production methods of magnetic nanoparticles for the bio-medical applications are discussed. X-ray powder diffractometry (XRD), scanning electron microscopy (SEM) and vibrating scanning magnetometer (VSM) were used to characterize the structural, morphological and magnetic properties. The particle size of samples is measured by Malvern Instruments Zeta Sizer Nano-ZS instrument. The temperature dependence of field cooled (FC) magnetization of all CuxMn1-xFe2O4 samples have been shown here. The data were recorded under 1k Oe and 100 Oe magnetic fields for different ratio.

Dogan, Nurcan

2013-03-01

399

Magnetic chitosan nanoparticles as a drug delivery system for targeting photodynamic therapy  

Microsoft Academic Search

Photodynamic therapy (PDT) has become an increasingly recognized alternative to cancer treatment in clinic. However, PDT therapy agents, namely photosensitizer (PS), are limited in application as a result of prolonged cutaneous photosensitivity, poor water solubility and inadequate selectivity, which are encountered by numerous chemical therapies. Magnetic chitosan nanoparticles provide excellent biocompatibility, biodegradability, non-toxicity and water solubility without compromising their magnetic

Yun Sun; Zhi-long Chen; Xiao-xia Yang; Peng Huang; Xin-ping Zhou; Xiao-xia Du

2009-01-01

400

Magnetic Silica-Supported Ruthenium Nanoparticles: An Efficient Catalyst for Transfer Hydrogenation of Carbonyl Compounds  

EPA Science Inventory

One-pot synthesis of ruthenium nanoparticles on magnetic silica is described which involve the in situ generation of magnetic silica (Fe3O4@ SiO2) and ruthenium nano particles immobilization; the hydration of nitriles and transfer hydrogenation of carbonyl compounds occurs in hi...

401

Fabrication and Characterization of Spinel Magnetic Nanoparticle Thin Film Transmission Lines  

E-print Network

1 Fabrication and Characterization of Spinel Magnetic Nanoparticle Thin Film Transmission Lines of Chemistry and Biochemistry, Georgia Institute of Technology Atlanta, Georgia 30332 USA Abshocr-Spinel of the measured effecfive dielectrichagnetic constant with simulated data. Index Terms-Spinel Magnetic

Papapolymerou, Ioannis "John"

402

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

PubMed

While more than 90% of cancer deaths are due to metastases, our ability to detect circulating tumor cells (CTCs) is limited by low numbers of these cells in the blood and factors confounding specificity of detection. We propose a magnetic enrichment and detection technique for detecting CTCs with high specificity. We targeted both magnetic and surface-enhanced Raman scattering (SERS) nanoparticles to cancer cells. Only cells that are dual-labeled with both kinds of nanoparticles demonstrate an increasing SERS signal over time due to magnetic trapping. PMID:24858132

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

2014-05-01

403

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

SciTech Connect

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

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

2007-01-01

404

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

SciTech Connect

In the present work is reported the use of the biopolymer chitosan as template for the preparation of magnetite and magnetite/silver core/shell nanoparticles systems, following a two step procedure of magnetite nanoparticles in situ precipitation and subsequent silver ions reduction. The crystalline and morphological characteristics of both magnetite and magnetite/silver core/shell nanoparticles systems were analyzed by high resolution transmission electron microscopy (HRTEM) and nanobeam diffraction patterns (NBD). The results of these studies corroborate the core/shell morphology and the crystalline structure of the magnetite core and the silver shell. Moreover, magnetization temperature dependent, M(T), measurements show an unusual diluted magnetic behavior attributed to the dilution of the magnetic ordering in the magnetite and magnetite/silver core/shell nanoparticles systems. - Graphical abstract: Biopolymer chitosan was used as stabilization media to synthesize both magnetite and magnetite/silver core/shell nanoparticles. Results of HRTEM and NBD patterns confirm core/shell morphology of the obtained nanoparticles. It was found that the composites show diluted magnet-like behavior.

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

2010-01-15

405

Radial breathing-mode frequency of elastically confined spherical nanoparticles subjected to circumferential magnetic field  

NASA Astrophysics Data System (ADS)

Knowledge of the vibrational properties of nanoparticles is of fundamental interest since it is a signature of their morphology, and it can be utilized to characterize their physical properties. In addition, the vibration characteristics of the nanoparticles coupled with surrounding media and subjected to magnetic field are of recent interest. This paper develops an analytical approach to study the radial breathing-mode frequency of elastically confined spherical nanoparticles subjected to magnetic field. Based on Maxwell's equations, the nonlocal differential equation of radial motion is derived in terms of radial displacement and Lorentz's force. Bessel functions are used to obtain a frequency equation. The model is justified by a good agreement between the results given by the present model and available experimental and atomic simulation data. Furthermore, the model is used to elucidate the effect of nanoparticle size, the magnetic field and the stiffness of the elastic medium on the radial breathing-mode frequencies of several nanoparticles. Our results reveal that the effects of the magnetic field and the elastic medium are significant for nanoparticle with small size.

Ghavanloo, E.; Fazelzadeh, S. A.; Murmu, T.; Adhikari, S.

2015-02-01

406

Magnetic and degradable polymer/bioactive glass composite nanoparticles for biomedical applications.  

PubMed

The present study focuses on the development of a biocompatible and biodegradable iron oxide incorporated chitosan-gelatin bioglass composite nanoparticles [Fe-BG]. The developed composite nanoparticle was analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, thermo gravimetric analysis (TG) and differential scanning calorimetry analysis (DSC). The size of the negatively charged composite nanoparticle was in the range of 43-51 nm. The in vitro analysis of the composite nanoparticles was carried out by cell aggregation, protein adsorption and haemolytic activity. The magnetic hysteresis value of the composite nanoparticle showed that it is a soft magnetic material. The presence of iron oxide in the chitosan-gelatin bi