Note: This page contains sample records for the topic antibody-coated magnetic nanoparticles from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Mass spectrometric detection of neuropeptides using affinity-enhanced microdialysis with antibody-coated magnetic nanoparticles.  

PubMed

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 to 18 h 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

2013-01-03

2

SERS-based sandwich immunoassay using antibody coated magnetic nanoparticles for Escherichia coli enumeration.  

PubMed

A method combining immunomagnetic separation (IMS) and surface-enhanced Raman scattering (SERS) was developed to enumerate Escherichia coli (E. coli). Gold-coated magnetic spherical nanoparticles were prepared by immobilizing biotin-labeled anti-E. coli antibodies onto avidin-coated magnetic nanoparticles and used in the separation and concentration of the E. coli cells. Raman labels have been constructed using rod shaped gold nanoparticles coated with 5,5-dithiobis-(2-nitrobenzoic acid) (DTNB) and subsequently with a molecular recognizer. Then DTNB-labeled gold nanorods were interacted with gold-coated magnetic spherical nanoparticle-antibody-E. coli complex. The capture efficiency and calibration graphs were obtained and examined in different E. coli concentrations (10(1)-10(7) cfu mL(-1)). The correlation between the concentration of bacteria and SERS signal was found to be linear within the range of 10(1)-10(4) cfu mL(-1) (R(2) = 0.992). The limit of detection (LOD) and limit of quantification (LOQ) values of the developed method were found to be 8 and 24 cfu mL(-1), respectively. The selectivity of the developed immunoassay was examined with Enterobacter aerogenes, Enterobacter dissolvens, and Salmonella enteriditis which did not produce any significant response. The ability of the immunoassay to detect E. coli in real water samples was also investigated and the results were compared with the experimental results from plate-counting methods. There was no significant difference between the methods that were compared (p > 0.05). This method is rapid and sensitive to target organisms with a total analysis time of less than 70 min. PMID:21125089

Guven, Burcu; Basaran-Akgul, Nese; Temur, Erhan; Tamer, Ugur; Boyaci, Ismail Hakki

2010-12-01

3

Targeting vascular amyloid in arterioles of Alzheimer disease transgenic mice with amyloid ? protein antibody-coated nanoparticles.  

PubMed

The relevance of cerebral amyloid angiopathy (CAA) to the pathogenesis of Alzheimer disease (AD) and dementia in general emphasizes the importance of developing novel targeting approaches for detecting and treating cerebrovascular amyloid (CVA) deposits. We developed a nanoparticle-based technology that uses a monoclonal antibody against fibrillar human amyloid-?42 that is surface coated onto a functionalized phospholipid monolayer. We demonstrate that this conjugated nanoparticle binds to CVA deposits in arterioles of AD transgenic mice (Tg2576) after infusion into the external carotid artery using 3 different approaches. The first 2 approaches use a blood vessel enrichment of homogenized brain and a leptomeningeal vessel preparation from thin tangential brain slices from the surface of the cerebral cortex. Targeting of CVA by the antibody-coated nanoparticle was visualized using fluorescent lissamine rhodamine-labeled phospholipids in the nanoparticles, which were compared with fluorescent staining of the endothelial cells and amyloid deposits using confocal laser scanning microscopy. The third approach used high-field strength magnetic resonance imaging of antibody-coated iron oxide nanoparticles after infusion into the external carotid artery. Dark foci of contrast enhancement in cortical arterioles were observed in T2*-weighted images of ex vivo AD mouse brains that correlated histologically with CVA deposits. The targeting ability of these nanoparticles to CVA provides opportunities for the prevention and treatment of CAA. PMID:21760540

Poduslo, Joseph F; Hultman, Kristi L; Curran, Geoffry L; Preboske, Gregory M; Chamberlain, Ryan; Marja?ska, Ma?gorzata; Garwood, Michael; Jack, Clifford R; Wengenack, Thomas M

2011-08-01

4

Functionalized magnetic nanoparticles for the detection and quantitative analysis of cell surface antigen.  

PubMed

Cell surface antigens as biomarkers offer tremendous potential for early diagnosis, prognosis, and therapeutic response in a variety of diseases such as cancers. In this research, a simple, rapid, accurate, inexpensive, and easily available in vitro assay based on magnetic nanoparticles and magnetic cell separation principle was applied to identify and quantitatively analyze the cell surface antigen expression in the case of prostate cancer cells. Comparing the capability of the assay with flow cytometry as a gold standard method showed similar results. The results showed that the antigen-specific magnetic cell separation with antibody-coated magnetic nanoparticles has high potential for quantitative cell surface antigen detection and analysis. PMID:23484112

Shahbazi-Gahrouei, Daryoush; Abdolahi, Mohammad; Zarkesh-Esfahani, Sayyed Hamid; Laurent, Sophie; Sermeus, Corine; Gruettner, Cordula

2012-12-31

5

Magnetic nanoparticles for theragnostics  

Microsoft Academic Search

Engineered magnetic nanoparticles (MNPs) represent a cutting-edge tool in medicine because they can be simultaneously functionalized and guided by a magnetic field. Use of MNPs has advanced magnetic resonance imaging (MRI), guided drug and gene delivery, magnetic hyperthermia cancer therapy, tissue engineering, cell tracking and bioseparation. Integrative therapeutic and diagnostic (i.e., theragnostic) applications have emerged with MNP use, such as

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

2009-01-01

6

Magnetic interactions between nanoparticles  

PubMed Central

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

Hansen, Mikkel Fougt; Frandsen, Cathrine

2010-01-01

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

Magnetic Nanoparticle Compositions and Methods.  

National Technical Information Service (NTIS)

A nanoparticle having a core comprising a magnetic material and surface to which are covalently coupled a plurality of silane moieties, wherein each silane moiety comprises a polyalkylene oxide moiety. The nanoparticle can further include a targeting agen...

J. W. Gunn M. Zhang N. Kohler

2006-01-01

10

Magnetic nanoparticles for theragnostics  

PubMed Central

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

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

2009-01-01

11

Magnetic nanoparticles for theragnostics.  

PubMed

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

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

2009-04-20

12

MAGNETIC NANOPARTICLES: PROPERTIES AND APPLICATIONS  

Microsoft Academic Search

Nanostructured materials often have unique electrical, chemical, structural and magnetic properties. Magnetic nanoparticles may be produced by physical vapour deposition, mechanical attritioning and chemical routes from solution. Through the control of the magnetic field gradient produced by an electromagnet or permanent magnet, these particles can be used to target or manipulate and transport targeted species to a desired location1,2,3. The

L L Vatta

13

Magnetic Nanoparticles for Cancer Therapy  

Microsoft Academic Search

Today, technologies based on magnetic nanoparticles (MNPs) are routinely applied to biological systems with diagnostic or therapeutic purposes. The paradigmatic example is the magnetic resonance imaging (MRI), a technique that uses the magnetic moments of MNPs as a disturbance of the proton resonance to obtain images. Similarly, magnetic fluid hyperthermia (MFH) uses MNPs as heat generators to induce localized cell

G. F. Goya; V. Grazu; M. R. Ibarra

2008-01-01

14

Cancer hyperthermia using magnetic nanoparticles.  

PubMed

Magnetic-nanoparticle-mediated intracellular hyperthermia has the potential to achieve localized tumor heating without any side effects. The technique consists of targeting magnetic nanoparticles to tumor tissue followed by application of an external alternating magnetic field that induces heat through Néel relaxation loss of the magnetic nanoparticles. The temperature in tumor tissue is increased to above 43°C, which causes necrosis of cancer cells, but does not damage surrounding normal tissue. Among magnetic nanoparticles available, magnetite has been extensively studied. Recent years have seen remarkable advances in magnetite-nanoparticle-mediated hyperthermia; both functional magnetite nanoparticles and alternating-magnetic-field generators have been developed. In addition to the expected tumor cell death, hyperthermia treatment has also induced unexpected biological responses, such as tumor-specific immune responses as a result of heat-shock protein expression. These results suggest that hyperthermia is able to kill not only local tumors exposed to heat treatment, but also tumors at distant sites, including metastatic cancer cells. Currently, several research centers have begun clinical trials with promising results, suggesting that the time may have come for clinical applications. This review describes recent advances in magnetite nanoparticle-mediated hyperthermia. PMID:22069094

Kobayashi, Takeshi

2011-08-26

15

One-step homogeneous magnetic nanoparticle immunoassay for biomarker detection directly in blood plasma.  

PubMed

Assay technologies capable of detecting low biomarker concentrations in complex biological samples are fundamental for biological research and for applications in medical diagnostics. In this paper we address the challenge to perform protein biomarker detection homogeneously in one single step, applying a minute amount of reagent directly into whole human blood plasma, avoiding any sample dilution, separation, amplification, or fluid manipulation steps. We describe a one-step homogeneous assay technology based on antibody-coated magnetic nanoparticles that are spiked in very small amount directly into blood plasma. Pulsed magnetic fields and a double-linker molecular architecture are used to generate high biomarker-induced binding and low nonspecific binding between the nanoparticles. We demonstrate dose-response curves for prostate specific antigen (PSA) measured in undiluted human blood plasma with a detection limit of 400-500 femtomol/L, in a total assay time of 14 min and an optically probed volume of only 1 nL. We explain the dose-response curves with a model based on discrete binding of biomarker molecules onto the nanoparticles, which allows us to extract reaction parameters for the binding of biomarker molecules onto the nanoparticles and for the biomarker-induced binding between nanoparticles. The demonstrated analytical performance and understanding of the nanoparticle assay technology render it of interest for a wide range of applications in quantitative biology and medical diagnostics. PMID:22414272

Ranzoni, Andrea; Sabatte, Gwenola; van Ijzendoorn, Leo J; Prins, Menno W J

2012-03-21

16

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

17

Properties and biomedical applications of magnetic nanoparticles  

Microsoft Academic Search

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

Rajesh Kumar Regmi

2011-01-01

18

Ordering of magnetic nanoparticles in bilayer structures  

NASA Astrophysics Data System (ADS)

In this study, we predict crystalline ordering of magnetic nanoparticles in a bilayer structure where only magnetic dipole interaction is taken into account. Estimates show that the two-dimensional lattice structure can be observed in the liquid nitrogen temperature regime. The results can be extended to magnetic nanoparticle multilayers. In addition, the study implies an order-disorder phase transition of the magnetic nanoparticle ensemble induced by external perpendicular magnetic fields.

Xi, Haiwen; Wang, Xiaobin; Chen, Yiran; Ryan, Pat J.

2009-01-01

19

Biomedical Applications of Magnetic Nanoparticles  

Microsoft Academic Search

Magnetic nanoparticles exhibit specific physical properties that make them a useful tool for both medical diagnostics and\\u000a therapy. The physical background for all these biomedical applications is the interaction of these particles with externally\\u000a applied magnetic fields. This interaction is confined to the particles so that unwanted side effects can be avoided or reduced.\\u000a In this chapter, the physics of

L. Trahms

20

Ordering of magnetic nanoparticles in bilayer structures  

Microsoft Academic Search

In this study, we predict crystalline ordering of magnetic nanoparticles in a bilayer structure where only magnetic dipole interaction is taken into account. Estimates show that the two-dimensional lattice structure can be observed in the liquid nitrogen temperature regime. The results can be extended to magnetic nanoparticle multilayers. In addition, the study implies an order-disorder phase transition of the magnetic

Haiwen Xi; Xiaobin Wang; Yiran Chen; Pat J. Ryan

2009-01-01

21

Aptamer conjugated magnetic nanoparticles as nanosurgeons  

Microsoft Academic Search

Magnetic nanoparticles have shown promise in the fields of targeted drug delivery, hyperthermia and magnetic resonance imaging (MRI) in cancer therapy. The ability of magnetic nanoparticles to undergo surface modification and the effect of external magnetic field in the dynamics of their movement make them an excellent nanoplatform for cancer destruction. Surgical removal of cancerous or unwanted cells selectively from

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

2010-01-01

22

Engineering biofunctional magnetic nanoparticles for biotechnological applications  

Microsoft Academic Search

Synthesis and characterization of magnetic nanoparticles with excellent size control are showed here. Their functionalization using an amphiphilic polymer is also described. This strategy allows the stabilization of magnetic nanoparticles in aqueous solvents and in addition, the polymer shell serves as a platform to incorporate relevant biomolecules, such as poly(ethylene glycol) and a number of carbohydrates. Nanoparticles functionalized with carbohydrates

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

2010-01-01

23

Intravenous magnetic nanoparticle cancer hyperthermia.  

PubMed

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

Huang, Hui S; Hainfield, James F

2013-07-17

24

Surface induced suppression of magnetization in nanoparticles  

Microsoft Academic Search

A model based on competing exchange interactions is presented for the investigation of nanoparticle magnetization. The ferromagnetic (FM) and antiferromagnetic (AFM) exchange interactions contribute differently at the nanoparticle surface and interior, leading to reduced ferromagnetic order at the surface. This model predicts an unconventional temperature dependence of magnetization and a surface magnetically 'dead layer'. This is confirmed by temperature dependent

C. Westman; S. Jang; C. Kim; S. He; G. Harmon; N. Miller; B. Graves; N. Poudyal; R. Sabirianov; H. Zeng; M. DeMarco; J. P. Liu

2008-01-01

25

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.

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

2008-01-01

26

Fighting cancer with magnetic nanoparticles and immunotherapy  

NASA Astrophysics Data System (ADS)

IFN-?-adsorbed DMSA-coated magnetite nanoparticles can be used as an efficient in vivo drug delivery system for tumor immunotherapy. Magnetic nanoparticles, with adsorbed interferon-?, were targeted to the tumor site by application of an external magnetic field. A relevant therapeutic dosage of interferon in the tumor was detected and led to a notable reduction in tumor size. In general, only 10% of the total injected nanoparticles after multiple exposures were found in tissues by AC susceptibility measurements of the corresponding resected tissues. Magnetic nanoparticle biodistribution is affected by the application of an external magnetic field.

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

2012-02-01

27

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

28

Magnetic nanoparticles for tunable microwave metamaterials  

NASA Astrophysics Data System (ADS)

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

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

29

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

30

Non-Bleaching Photoluminescent Magnetic Nanoparticles  

NASA Astrophysics Data System (ADS)

We report a new type of photoluminescent magnetic nanoparticles produced by a very simple process. The nanoparticle consists of an ordinary magnetic nanoparticle as core and a non-toxic polymer shell. The biocompatibility is evaluated using in-vivo tests on mice. They are non-bleaching photoluminescent without any addition of fluorophores, such as quantum dots or fluorescent dyes that can be toxic and easily photobleached, respectively. This work provides a low-cost, bio-safe, non-bleaching alternative of conventional fluoroscent magnetic nanoparticles which covers a wide range of applications, from bio-imaging to biomedical diagnostics and therapeutics, such as hyperthermia.

Zou, Lu; Kim, Chanjoong; Girgis, Emad; Khalil, Wagdy K. B.

2013-03-01

31

Medical application of functionalized magnetic nanoparticles.  

PubMed

Since magnetic particles have unique features, the development of a variety of medical applications has been possible. The most unique feature of magnetic particles is their reaction to a magnetic force, and this feature has been utilized in applications such as drug targeting and bioseparation including cell sorting. Recently, magnetic nanoparticles have attracted attention because of their potential as contrast agents for magnetic resonance imaging (MRI) and heating mediators for cancer therapy (hyperthermia). Magnetite cationic liposomes (MCLs), one of the groups of cationic magnetic particles, can be used as carriers to introduce magnetite nanoparticles into target cells since their positively charged surface interacts with the negatively charged cell surface; furthermore, they find applications to hyperthermic treatments. Magnetite nanoparticles conjugated with antibodies (antibody-conjugated magnetoliposomes, AMLs) are also applied to hyperthermia and have enabled tumor-specific contrast enhancement in MRI via systemic administration. Since magnetic nanoparticles are attracted to a high magnetic flux density, it is possible to manipulate cells labeled with magnetic nanoparticles using magnets; this feature has been applied in tissue engineering. Magnetic force and MCLs were used to construct multilayered cell structures and a heterotypic layered 3D coculture system. Thus, the applications of these functionalized magnetic nanoparticles with their unique features will further improve medical techniques. PMID:16233845

Ito, Akira; Shinkai, Masashige; Honda, Hiroyuki; Kobayashi, Takeshi

2005-07-01

32

Synthesis and characterization of functionalized magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles have been used in a wide array of industrial and biomedical applications due to their unique properties at the nanoscale level. They are extensively used in magnetic resonance imaging (MRI), magnetic hyperthermia treatment, drug delivery, and in assays for biological separations. Furthermore, superparamagnetic nanoparticles are of large interest for in vivo applications. However, these unmodified nanoparticles aggregate and consequently lose their superparamagnetic behaviors, due to high surface to volume ratio and strong dipole to dipole interaction. For these reasons, surface coating is necessary for the enhancement and effectiveness of magnetic nanoparticles to be used in various applications. In addition to providing increased stability to the nanoparticles in different solvents or media, stabilizers such as surfactants, organic/inorganic molecules, polymer and co-polymers are employed as surface coatings, which yield magnetically responsive systems. In this work we present the synthesis and magnetic characterization of Fe3O4 nanoparticles coated with 3-aminopropyltriethoxy silane (APS) and citric acid. The particles magnetic hysteresis was measured by a superconducting quantum interference device (SQUID) magnetometer with an in-plane magnetic field. The uncoated and coated magnetic nanoparticles were characterized by using fourier transform infrared (FTIR), UV-vis, X-ray diffraction, transmission electron microscopy, and thermo-gravimetric analysis.

Biswal, Dipti; Peeples, Brianna N.; Spence, Destiny D.; Peeples, Caryn; Bell, Crystal N.; Pradhan, A. K.

2012-03-01

33

Engineering biofunctional magnetic nanoparticles for biotechnological applications  

NASA Astrophysics Data System (ADS)

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

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

2010-09-01

34

Biomedical Applications of Magnetic Nanoparticles and Fluids  

Microsoft Academic Search

Nanomaterials play an increasingly important role in the research, diagnosis and treatment of numerous pathologies. Biomedical applications such as drug delivery, magnetic resonance imaging and hyperthermia require magnetic nanoparticles with a large saturation magnetization that are biocompatible, form stable suspensions in water-based fluids, and can be functionalized. We use chemical synthesis and inert-gas condensation into fluids to produce biocompatible magnetic

Diandra Leslie-Pelecky

2006-01-01

35

Tailoring magnetic properties of Co-ferrite soft magnetic nanoparticles  

Microsoft Academic Search

Monodisperse Co-ferrite soft magnetic nanoparticles with particle size from 3 nm to 20 nm and different Co concentration have been synthesized by chemical solution methods. The composition was controlled by varying the mole ratios of the precursors in the solution. It has been found that magnetic properties of the nanoparticles can be tailored by changing the composition, particle size, as

N. Poudyal

2005-01-01

36

The Effects of Magnetic Nanoparticles on Magnetic Fluid Hyperthermia  

Microsoft Academic Search

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

Monrudee Liangruksa; Ravi Kappiyoor; Ranjan Ganguly; Ishwar Puri

2010-01-01

37

Manipulation of magnetic nanoparticles using microelectromagnets  

NASA Astrophysics Data System (ADS)

Microscopic manipulations of magnetic nanoparticles and magnetotactic bacteria were demonstrated using a microelectromagnet matrix and a microelectromagnet ring trap[1]. The ring trap is a single circular Au wire with an insulator spun on top, while the matrix is a multilayered structure of lithographically patterned Au wires and insulators with the capability of two dimensional manipulations of magnetic nanoparticles. We have demonstrated the trapping of superparamagnetic nanoparticles and magnetotactic bacteria with the ring trap. With the matrix, we were able to trap superparamagnetic nanoparticles at desired locations, to move these particles continuously over the surface of the device with micron scale spatial resolutions, and to join two separate clusters of particles into one. We also discuss the possibility of controlling a single magnetic nanoparticle with microelectromagnet devices. [1] C.S. Lee, H. Lee and R.M. Westervelt, Appl. Phys. Lett. 79, 3308 (2001)

Lee, C. S.; Lee, H.; Westervelt, R. M.

2002-03-01

38

Magnetic properties of monodisperse iron oxide nanoparticles  

Microsoft Academic Search

We have synthesized a set of monodisperse iron oxide nanoparticles ranging from 7.8 to 17.9 nm by thermal decomposition methods. Based on the evidence of high-resolution transmission electron microscopy, the iron oxide nanoparticles appear as spherical dots with size standard deviations of less than 5%. Blocking temperatures of the set of nanoparticles were measured by the zero-field-cooled magnetization measurements. The

Chun-Rong Lin; Ray-Kuang Chiang; Jiun-Shen Wang; Ti-Wen Sung

2006-01-01

39

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

40

Bifunctional bacterial magnetic nanoparticles for tumor targeting  

NASA Astrophysics Data System (ADS)

Bifunctional bacterial magnetic nanoparticles (BBMPs), which present both magnetic drug targeting and tumor bio-targeting properties, have been developed by chemically coupling both doxorubicin and a galactosyl ligand on to the membrane surface of the bacterial magnetic nanoparticles (BMPs). The BBMP product has a high drug load ratio and magnetic respondence, and exhibits a narrow size distribution and is sensitive to pH to enable drug release. In comparison to doxorubicin-coupled BMPs, without modification with a galactosyl ligand, BBMPs present a higher uptake by the target asialoglycoprotein receptor (ASGP-R) expressed by HepG2 cells and display stronger cytotoxicity.

Guo, Lin; Huang, Ji; Zheng, Li-Min

2012-01-01

41

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

42

Biomedical Applications of Magnetic Nanoparticles and Fluids.  

NASA Astrophysics Data System (ADS)

Nanomaterials play an increasingly important role in the research, diagnosis and treatment of numerous pathologies. Biomedical applications such as drug delivery, magnetic resonance imaging and hyperthermia require magnetic nanoparticles with a large saturation magnetization that are biocompatible, form stable suspensions in water-based fluids, and can be functionalized. We use chemical synthesis and inert-gas condensation into fluids to produce biocompatible magnetic nanoparticle fluids that allow magnetic targeting of drugs and simultaneous magnetic resonance imaging. We have developed a water-dispersible oleic-acid/Pluronic/iron-oxide nanoparticle formulation that can be loaded with high doses of water-insoluble anti-cancer drugs. An external magnetic field is used to attract the nanoparticles to the treatment region and MRI is used to verify their location. A primary limitation on magnetic targeting, however, is the low moment of iron-oxide nanoparticles. Inert-gas-condensation into fluids produces iron and cobalt nanoparticles from 5-45 nm in diameter. Coating or passivation of these materials is required to prevent oxidation; however, the interaction between surface atoms and surfactant or other functionalizing molecules can greatly diminish the magnetic moment. A study of surfactant interactions with iron nanoparticles shows that the physical barrier provided by a concentric shell of polymeric surfactant offers significantly more protection against oxidation than the radial barrier formed by most linear surfactants. The talk will conclude with a brief overview of the opportunities and challenges for condensed matter and materials physicists in biomagnetic materials. This work is done in collaboration with V. Labhasetwar and T. Jain at the University of Nebraska Medical Center, and Marco Morales, Nguyen Hai, Shannon Fritz, Kishore Sreenivasan and David Schmitter at the University of Nebraska -- Lincoln.

Leslie-Pelecky, Diandra

2006-03-01

43

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

44

High-gradient magnetic separation of coated magnetic nanoparticles  

Microsoft Academic Search

The feasibility is examined of using high-gradient magnetic separation (HGMS) to recover about 8-nm magnetite nanoparticles that are tailored specifically to extract target solutes (polymer-coated nanoparticles for the extraction of soluble organic contaminants from water and phospholipid-coated particles for the selective extraction of proteins). A general model for nanoparticle capture based on calculating the limit of static nanopar- ticle buildup

Geoffrey D. Moeser; Kaitlin A. Roach; William H. Green; T. Alan Hatton; Paul E. Laibinis

2004-01-01

45

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.

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

2011-01-01

46

Thermal potentiation of chemotherapy by magnetic nanoparticles.  

PubMed

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

2013-10-01

47

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

48

Using magnetic nanoparticles to manipulate biological objects  

NASA Astrophysics Data System (ADS)

The use of magnetic nanoparticles (MNPs) for the manipulation of biological objects, including proteins, genes, cellular organelles, bacteria, cells, and organs, are reviewed. MNPs are popular candidates for controlling and probing biological objects with a magnetic force. In the past decade, progress in the synthesis and surface engineering of MNPs has further enhanced this popularity.

Liu, Yi; Gao, Yu; Xu, Chenjie

2013-09-01

49

Dynamics of magnetic nano-particle assembly  

Microsoft Academic Search

Ferromagnetically coupled nano-particle assembly is analyzed accounting for inter- and intra- particle electronic structures within the randomly jumping interacting moments model including quantum fluctuations due to the discrete levels and disorder. At the magnetic jump anomalies caused by quantization the magnetic state equation and phase diagram are found to indicate an existence of spinodal regions and critical points. Arrays of

V. N. Kondratyev

2010-01-01

50

Magnetic nanoparticles: Internal probes and heaters within living cells  

Microsoft Academic Search

Tagging living cells with magnetic nanoparticles raised increasing interest in the fields of magnetic resonance imaging, magnetic hyperthermia, cell sorting or tissue engineering. Here, we demonstrate that the confinement of magnetic nanoparticles at the intracellular level, inside endosomes vesicles, allows developing original magnetic manipulations in response to different magnetic field solicitations. These manipulations are used to deform cellular internal membrane,

Claire Wilhelm; Florence Gazeau

2009-01-01

51

Biocompatible magnetic nanoparticles with high magnetic moment for cancer treatment  

NASA Astrophysics Data System (ADS)

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

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

2007-05-01

52

Magnetic Nanoparticle Arrays prepared via Coaxial Electrospinning  

NASA Astrophysics Data System (ADS)

One dimensional nanoparticle (1D NP) arrays display strong anisotropy in their physical properties making them interesting from a fundamental as well as applications perspective. 1D arrays of Fe3O4 nanoparticles have been constructed by encapsulating magnetite nanoparticles within Poly(ethylene oxide) nanofibers, by a modified solution spinning process. Electrospinning is a facile process for creating 1D nanostructures and a simple modification to the process renders a coaxial delivery mechanism that facilitates the construction of nanoparticle arrays. These hybrid 1D nanomaterials were structurally characterized by electron microscopy and the magnetic characteristics of these fiber encapsulated particle arrays were studied using vibrating sample magnetometry. Anisotropic magnetic behavior along different orthogonal axes (parallel and perpendicular) was observed even at room temperature with an appreciable increase in coercivity in the perpendicular configuration. Experimental work is underway to use these particle arrays as precursor materials for the creation of magnetite nanorods.

Sharma, Nikhil; Jaffari, Hassnain; Shah, Ismat; Pochan, Darrin

2009-03-01

53

High Magnetization Polyethylene Glycol Coated Nanoparticles  

NASA Astrophysics Data System (ADS)

High magnetization nanoparticles coated with a biocompatible polymer or poly-saccharide layer are required for biomedical applications such as targeted drug delivery, MRI contrast enhancement and hyperthermia treatments. This paper discusses the fabrication and characterization of iron nanoparticles coated with carboxyl terminated polyethylene glycol for future biomedical applications. Electron microscopy reveals nanoparticles ranging from 10 to 50 nm in size that have a body centered cubic structure characteristic of alpha Fe. Mossbauer spectroscopy reveals the typical sextet expected for Fe with two different hyperfine fields reminiscent of a core shell morphology indicating that there are two distinct Fe sites. The coated nanoparticles are soft ferromagnets with coercivity below 100 Oe and a saturation magnetization of 50 emu/g as shown by SQUID and vibrating sample magnetometry. Optimization studies are underway and the results will be reported.

Bonder, M. J.; Papaefthymiou, V.

2005-03-01

54

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...

55

Stability of magnetic nanoparticles inside ferromagnetic nanotubes  

NASA Astrophysics Data System (ADS)

During the last years great attention has been given to the encapsulation of magnetic nanoparticles. In this work we investigated the stability of small magnetic particles inside magnetic nanotubes. Multisegmented geometries were tested in order to optimize the stability of the particle inside the nanotubes. Our results evidenced that multisegmented nanotubes are more efficient to entrap the particles at temperatures up to hundreds of kelvins.

Neumann, R. F.; Bahiana, M.; Escrig, J.; Allende, S.; Nielsch, K.; Altbir, D.

2011-01-01

56

Magnetic Nanoparticles for Diagnosis and Medical Therapy  

Microsoft Academic Search

\\u000a Magnetic nanoparticles (MNPs) reveal promising opportunities for biomedical applications, potentially allowing minimally invasive\\u000a diagnosis and therapeutic usage at several levels of human body organization (cells, tissue and organs). An increasingly broad\\u000a collection of MNPs has been recently developed not only at the research level but also in some specific cases for medical\\u000a applications. Superparamagnetic iron oxide (SPIO) nanoparticles are commonly

Martin Sobik; Kirsten M. Pondman; Ben Erné; Bonny Kuipers; Bennie ten Haken; Horst Rogalla

57

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

58

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.

Weaver, John B.; Kuehlert, Esra

2012-01-01

59

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

2013-09-09

60

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

61

Microfluidic Biosensing Systems Using Magnetic Nanoparticles  

PubMed Central

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

Giouroudi, Ioanna; Keplinger, Franz

2013-01-01

62

Magnetic properties of nickel hydroxide nanoparticles  

NASA Astrophysics Data System (ADS)

The magnetic properties of 10 nm size Ni(OH)2 nanoparticles prepared by sol-gel method have been studied. The magnetic moments increase with decreasing temperature in a low applied field, which is due to the spin-frozen-like state at low temperatures, and the metamagnetic transition is not clearly observed even in an applied field of 70 kOe due to the size effect. Furthermore, the transition from paramagnetic to antiferromagnetic in the Ni(OH)2 nanoparticles occurs at lower temperature (22 K).

Liu, X. H.; Liu, W.; Lv, X. K.; Yang, F.; Wei, X.; Zhang, Z. D.; Sellmyer, D. J.

2010-04-01

63

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.

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

2012-01-01

64

Surface Induced Suppression of Magnetization and Surface magnetization Reversal in Magnetic Nanoparticles  

Microsoft Academic Search

Ferrite nanoparticles show strong size and surface dependent magnetic properties. These manifest themselves as a reduced magnetization with decreasing size and an unconventional temperature dependence of magnetization. These effects can be attributed to competing exchange interactions that contribute differently at the nanoparticle surface and interior, leading to reduced ferromagnetic order at the surface. A simple model is constructed that are

Chaehyun Kim; Wei Lai; Renat Sabirianov; Yuhang Ren; Hao Zeng

2010-01-01

65

Preparation and characterization of magnetic nanoparticles with controlled magnetization  

Microsoft Academic Search

The effect of molar ratio of two hydrated iron salts used as precursors into a (co)precipitation-based synthesis method, on\\u000a the composition, size and specific saturation magnetization of mixed iron oxides and oxyhydroxides magnetic nanoparticles\\u000a as reaction products, was studied. The preparation procedure is based on a salt-assisted solid-state chemical reaction. The\\u000a obtained products are magnetic multiphase components with the mean

Dumitru-Daniel Herea; Horia Chiriac; Nicoleta Lupu

66

Multifunctional magnetic nanoparticles for magnetic resonance imaging and cancer therapy  

Microsoft Academic Search

We have developed a multi-layer approach for the synthesis of water-dispersible superparamagnetic iron oxide nanoparticles for hyperthermia, magnetic resonance imaging (MRI) and drug delivery applications. In this approach, iron oxide core nanoparticles were obtained by precipitation of iron salts in the presence of ammonia and provided ?-cyclodextrin and pluronic polymer (F127) coatings. This formulation (F127250) was highly water dispersible which

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

2011-01-01

67

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

68

Earth Nanoparticles with Novel Magnetic Properties  

NASA Astrophysics Data System (ADS)

Our previous studies on Dy nanoparticles showed unique and interesting properties different from bulk^1. In this study we used another technique to prepare Dy and Gd nanoparticles in large quantities needed for further characterization. The rare earth (R=Dy,Gd) nanoparticles were made from sputtered R/W multilayers which were annealed in the temperature range of 500-700°C to form R nanoparticles in the W matrix. The magnetic properties were measured with a SQUID magnetometer. The microstructure and crystal structure were studied with a Jeol JEM-2000FX TEM. The as-made films exhibit amorphous like structure. At the early stages of annealing, the systems showed superparagmagnetic behavior with the blocking temperature increasing with particle size. The magnetic transition in the range of 90-120 K was observed when the particle size increased to about 8 nm. However, the antiferromagnetic to paramagnetic transition which for bulk Dy is at 176K is not observed in these films as consistent with our previous studies. More interestingly, after prolonged annealing, the magnetic transition temperature is decreased instead of increasing as expected for larger particles. EXAFS studies are being planned to further understand the behavior of the Dy nanoparticles. Work supported by NSF under Grant No. DMR 9972035 1. N.B. Shevchenko, et al., Appl. Phys. Lett. 74, 1478

Huang, Yunhe; Okumura, Hideyuki; Christodoulides, Joseph; Hadjipanayis, George; Harris, Vince

2000-03-01

69

Magnetic Nanoparticles for Cancer Diagnosis and Therapy  

PubMed Central

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

Yigit, Mehmet V.; Moore, Anna

2013-01-01

70

Magnetic nanoparticles for application in cancer therapy  

NASA Astrophysics Data System (ADS)

Magnetic particles play nowadays an important role in different technological areas with potential applications in fields such as electronics, energy and biomedicine. In this report we will focus on the hyperthermia properties of magnetite nanoparticles and the effect of several chemical/physical parameters on their heating properties. We will discuss about the need of searching new smaller magnetic systems in order to fulfill the required physical properties which allow treating tumoral tissues more efficiently by means of magnetically induced heat. Preliminary results will be shown about the effect of a biocompatible shell of core-shell magnetite NPs on the heating properties by application of a RF magnetic field.

Rivas, J.; Bañobre-López, M.; Piñeiro-Redondo, Y.; Rivas, B.; López-Quintela, M. A.

2012-10-01

71

Magnetic Nanoparticles for Self-Controlled Hyperthermia  

Microsoft Academic Search

Localized heating utilizing magnetic nanoparticles is studied. The particles generate heat when subjected to alternating filed. In order to avoid spot heating the particles are synthesized with controlled Curie temperature of less than 44oC. In the present paper 4 ) 2 ( 5 . 0 5 . 0 O

Yousef Haik; Saud Khashan; Virendra Mohite

72

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

73

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

Microsoft Academic Search

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

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

2008-01-01

74

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

75

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

76

Effects of iron oxide magnetic nanoparticles on osteoblast proliferation  

Microsoft Academic Search

Iron oxide nanoparticles are promising candidates for drug delivery systems to treat osteoporosis due to their biocompatibility and magnetic properties. Magnetite and maghemite nanoparticles were synthesized here using a co-precipitation method. The particles were characterized by transmission electron microscopy (TEM). Effects of CaP coating iron oxide magnetic nanoparticles on the proliferation of osteoblasts (OB) were determined after 1, 3 and

N. Tran; Rajesh Pareta; Thomas Webster

2009-01-01

77

Second harmonic generation in magnetic nanoparticles with vortex magnetic state  

NASA Astrophysics Data System (ADS)

Nonlinear optical properties of a regular array of triangular-shaped vortex magnetic nanoparticles is studied using the optical second harmonic generation (SHG) technique. We demonstrate that the SHG azimuthal anisotropy is consistent with the 3m symmetry of individual Co nanodots placed in a square surface lattice. Qualitatively different SHG magnetic hysteresis loops are obtained for circular and linear polarizations of the fundamental radiation. In the first case, a wide SHG hysteresis at zero DC magnetic field H is observed, which is attributed to a macroscopic magnetic toroid moment in Co nanodots induced by a noncentrosymmetric distribution of the magnetization. On the contrary, for the linear pump polarization the SHG loop is similar to observed commonly in linear magnetooptics for vortex magnetic structures and reveals a rather narrow width at H=0. A phenomenological SHG description based on the introduction of the SHG polarization induced by a magnetic toroid moment in vortex magnetic nanostructures is presented.

Krutyanskiy, V. L.; Kolmychek, I. A.; Gribkov, B. A.; Karashtin, E. A.; Skorohodov, E. V.; Murzina, T. V.

2013-09-01

78

Targeting Cancer Gene Therapy with Magnetic Nanoparticles  

PubMed Central

Recent advances in cancer genomics have opened up unlimited potential for treating cancer by directly targeting culprit genes. However, novel delivery methods are needed in order for this potential to be translated into clinically viable treatments for patients. Magnetic nanoparticle technology offers the potential to achieve selective and efficient delivery of therapeutic genes by using external magnetic fields, and also allows simultaneous imaging to monitor the delivery in vivo. Compared to conventional gene delivery strategies, this technique has been shown to significantly increase gene delivery to human xenograft tumors models, as well as various internal organs (e.g. liver, kidney) and the central nervous system. Magnetic nanoparticle technology, therefore, has the potential to turn the challenge of gene therapy in vivo into a new frontier for cancer treatment.

Li, Charles; Li, Linda; Keates, Andrew C.

2012-01-01

79

Nanoparticles for cancer therapy using magnetic forces.  

PubMed

The term 'nanomedicine' refers to the use of nanotechnology in the treatment, diagnosis and monitoring of diseases. Magnetic drug targeting is a particularly promising application in this field. The goal of the carrier systems involved is to achieve active enrichment of effective substances in diseased tissue. Numerous nanosystems can be used as carriers, but magnetic iron oxide nanoparticles are particularly important. On the one hand, the particles serve as carriers for the active substance, while on the other hand they can also be visualized using conventional imaging techniques and can therefore be used for 'theranostic' purposes. They can also be used in hyperthermia, another important pillar of nanomedicine. Both procedures are intended to lead to specific forms of treatment, which is of medical and economic relevance in view of the increasing numbers of cancer patients worldwide. This study offers a brief overview of current developments in medical applications for magnetic nanoparticles in cancer therapy. PMID:22385201

Tietze, Rainer; Lyer, Stefan; Dürr, Stephan; Alexiou, Christoph

2012-03-01

80

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.

Fang, Chen; Zhang, Miqin

2010-01-01

81

Tracking stem cells using magnetic nanoparticles  

PubMed Central

Stem cell therapies offer great promise for many diseases, especially those without current effective treatments. It is believed that noninvasive imaging techniques, which offer the ability to track the status of cells after transplantation, will expedite progress in this field and help to achieve maximized therapeutic effect. Today’s biomedical imaging technology allows for real-time, noninvasive monitoring of grafted stem cells including their biodistribution, migration, survival, and differentiation, with magnetic resonance imaging (MRI) of nanoparticle-labeled cells being one of the most commonly used techniques. Among the advantages of MR cell tracking are its high spatial resolution, no exposure to ionizing radiation, and clinical applicability. In order to track cells by MRI, the cells need to be labeled with magnetic nanoparticles, for which many types exist. There are several cellular labeling techniques available, including simple incubation, use of transfection agents, magnetoelectroporation, and magnetosonoporation. In this overview article, we will review the use of different magnetic nanoparticles and discuss how these particles can be used to track the distribution of transplanted cells in different organ systems. Caveats and limitations inherent to the tracking of nanoparticle-labeled stem cells are also discussed.

Cromer Berman, Stacey M.; Walczak, Piotr; Bulte, Jeff W.M.

2011-01-01

82

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.

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

2013-01-01

83

Piezoelectric immunosensor based on magnetic nanoparticles with simple immobilization procedures  

Microsoft Academic Search

A novel method for immobilizing antibodies (antigens) based on magnetic nanoparticles has been proposed for piezoelectric immunoassay. The goat-anti-IgG antibody (IgGAb) as the model analyte was first covalently immobilized to magnetic nanoparticles, which were surface modified with amino-groups. The magnetic bio-nanoparticles (MBN-s) formed were attached to the surfaces of quartz crystal with the help of a permanent magnet. The detection

Jishan Li; Xiaoxiao He; Zhaoyang Wu; Kemin Wang; Guoli Shen; Ruqin Yu

2003-01-01

84

Properties of Magnetic Nanoparticles for Magnetic Immunoassays Utilizing a Superconducting Quantum Interference Device  

Microsoft Academic Search

Properties of magnetic nanoparticles are studied for application to magnetic immunoassays utilizing a superconducting quantum interference device (SQUID). In this application, a magnetic marker is made of magnetic nanoparticles, and the binding reaction between an antigen and its antibody is detected by measuring the magnetic field from the marker. Magnetization of an assembly of the particles is simulated when the

Keiji Enpuku; Katsuhiro Inoue; Kazuyuki Soejima

2005-01-01

85

[Antibody-coated bacteriuria and localization of urinary tract infection].  

PubMed

Antibody-coated bacteriuria (ACB) test was proposed as a tool for localisation of urinary tract infection (UTI). Our own results and a review of the literature give the following percentage: 85% ACB + in parenchymatous infection, 93% ACB--in lower UTI. The discrepancies observed from one group to the other show the importance of several parameters: the lack of standardization of the technic, the value of monospecific vs polyspecific antisera, the variability of some bacterial properties, the type of investigated patients. When these different parameters are well defined, the ACB test appears to be the most valuable technic to evaluate the renal risk of UTI. PMID:6759965

Fries, D

1982-01-01

86

Magnetic resonance of ferrite nanoparticles  

Microsoft Academic Search

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

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

1998-01-01

87

Synthesis and Characterization of Magnetic Iron Oxide Nanoparticles  

SciTech Connect

This paper reports the synthesis and characterization of iron oxide nanoparticles and their assembly towards thin film materials. The results have provided important insights into the design of interfacial reactivities via iron nanoparticles for magnetic, catalytic and biological applications.

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

2005-05-05

88

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

2013-04-22

89

Applications and potential toxicity of magnetic iron oxide nanoparticles.  

PubMed

Owing to their unique physical and chemical properties, magnetic iron oxide nanoparticles have become a powerful platform in many diverse aspects of biomedicine, including magnetic resonance imaging, drug and gene delivery, biological sensing, and hyperthermia. However, the biomedical applications of magnetic iron oxide nanoparticles arouse serious concerns about their pharmacokinetics, metabolism, and toxicity. In this review, the updated research on the biomedical applications and potential toxicity of magnetic iron oxide nanoparticles is summarized. Much more effort is required to develop magnetic iron oxide nanoparticles with improved biocompatible surface engineering to achieve minimal toxicity, for various applications in biomedicine. PMID:23019129

Liu, Gang; Gao, Jinhao; Ai, Hua; Chen, Xiaoyuan

2012-09-28

90

Magnetic field heating study of Fe-doped Au nanoparticles  

NASA Astrophysics Data System (ADS)

Fe-doped Au nanoparticles are ideal for biological applications over magnetic oxides due to their conjugation chemistry, optical properties, and surface chemistry. We present an AC magnetic field heating study of 8 nm Fe-doped Au nanoparticles which exhibit magnetic behavior. Magnetic heating experiments were performed on stable aqueous solutions of the nanoparticles at room temperature. The nanoparticles exhibit magnetic field heating, with a specific absorption rate (SAR) of 1.84 W/g at 40 MHz and H=100 A/m. The frequency dependence of the heating follows general trends predicted by power loss equations and is similar to traditional materials.

Wijaya, Andy; Brown, Katherine A.; Alper, Joshua D.; Hamad-Schifferli, Kimberly

2007-02-01

91

High-magnetic-moment multifunctional nanoparticles for nanomedicine applications  

Microsoft Academic Search

Multifunctional FeCo nanoparticles with narrow size distribution (less than 8% standard deviation) were fabricated by a novel physical vapor nanoparticle-deposition technique. The size of magnetic nanoparticles was controlled in the range from 3 to 100nm. The shape of nanoparticles was controlled to be either spherical or cubic. The particles had a high specific magnetization of 226emu\\/g at low saturation field,

Yun Hao Xu; Jianmin Bai; Jian-Ping Wang

2007-01-01

92

Poly(allylamine) Stabilized Iron Oxide Magnetic Nanoparticles  

Microsoft Academic Search

This paper describes a new method for the dispersing and surface-functionalization of metal oxide magnetic nanoparticles (10 nm)\\u000a with poly(allylamine) (PAA). In this approach, Fe3O4 nanoparticles, prepared with diethanolamine (DEA) as the surface capping agent in diethyleneglycol (DEG) and methanol, are\\u000a ligand exchanged with PAA. This method allows the dispersing of magnetic nanoparticles into individual or small clusters of\\u000a 2–5 nanoparticles

Jouliana M. El Khoury; Daniela Caruntu; Charles J. O’ Connor; Kwang-Un Jeong; Stephen Z. D. Cheng; Jun Hu

2007-01-01

93

Self-assembly and magnetic properties of cobalt nanoparticles  

NASA Astrophysics Data System (ADS)

Two- and three-dimensional superlattices of passivated cobalt nanoparticles were formed by a self-assembly technique. The size and stabilization of the cobalt nanoparticles are controlled by using the combination of oleic acid and triphenylphosphine. The cobalt nanoparticles are stable for at least 90 days without oxidation at room temperature under ambient conditions. The magnetic properties of the cobalt nanoparticles in different forms are compared, which provides helpful information on the magnetostatic interaction of the nanoparticles.

Yang, H. T.; Shen, C. M.; Su, Y. K.; Yang, T. Z.; Gao, H. J.; Wang, Y. G.

2003-06-01

94

Photoconjugation of molecularly imprinted polymer with magnetic nanoparticles.  

PubMed

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

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

2013-05-14

95

Functional magnetic nanoparticles for medical application  

NASA Astrophysics Data System (ADS)

We prepared an amino-substituted nanoparticle by means of the amino-silane coupling procedure. The original magnetic particles were ?-Fe2O3, which ranged in size from 1.3 to 34 nm, surrounded by amorphous SiO2. The modification of the magnetic particle by the addition of an amino group was confirmed using a Fourier transform infrared spectrophotometer (FT-IR). The X-ray diffraction patterns showed a spinel structure both before and after modification of the amino group. The magnetization curve indicated paramagnetic behavior for the 3 nm particles, superparamagnetic behavior for the 7 nm particles, and ferromagnetic behavior for 9 nm particles at room temperature. A fluorescent reagent was applied to the particle, and the particle was introduced into a cell. The magnetic particles in the cell were localized using an external magnetic field.

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

2007-03-01

96

Importance of specific magnetic moment and size monodispersity of magnetic nanoparticles for biomedical applications  

Microsoft Academic Search

Magnetic nanoparticles with suitable biocompatible coatings are becoming increasingly important recentlt in biomedical applications. In most cases people just use nanoparticles but don't pay much attention to their magnetic properties and size effects, which could improve greatly the applications. There are very few publications dealing with underlying physics and discussing how the magnetic properties and size distribution of nanoparticles influence

You Qiang

2005-01-01

97

Modeling magnetic nanoparticle dipole-dipole interactions inside living cells  

NASA Astrophysics Data System (ADS)

Biomedical applications based on superparamagnetic nanoparticles injected in vivo may be affected by the cellular uptake of these nanoparticles. Living cells indeed capture and internalize nanoparticles, concentrating them into intracellular vesicles called lysosomes. As a consequence, nanoparticles interact magnetically with each other, modifying their magnetic properties. The effects of cellular uptake can be observed on the temperature dependence of zero-field cooled (ZFC) magnetization, which is known to be sensitive to magnetic interactions. In this paper, a theoretical model is proposed to account for weak magnetic interactions between nanoparticles aggregated into spherical compartments. This model suggests a new interpretation of the maximum of the ZFC curve, uncorrelated with the nanoparticle relaxation time but with the extent of interaction effects. It focuses on the local field felt by each nanoparticle, which is the sum of the applied magnetic field and the field created by all the other nanoparticles. For the considered organization of nanoparticles, only the field created by touching neighbors has to be taken into account, setting up the local nanoparticle volume fraction as the unique parameter of the model. This parameter relates the global magnetization measurements to the local distribution of nanoparticles in cells and tissues or in other complex media with aggregated organization.

Lévy, Michael; Gazeau, Florence; Bacri, Jean-Claude; Wilhelm, Claire; Devaud, Martin

2011-08-01

98

Synthesis, properties, and applications of magnetic iron oxide nanoparticles  

Microsoft Academic Search

Magnetic nanoparticles exhibit many interesting properties that can be exploited in a variety of applications such as catalysis and in biomedicine. This review discusses the properties, applications, and syntheses of three magnetic iron oxides – hematite, magnetite, and maghemite – and outlines methods of preparation that allow control over the size, morphology, surface treatment and magnetic properties of their nanoparticles.

Amyn S. Teja; Pei-Yoong Koh

2009-01-01

99

Hyperthermic effect of magnetic nanoparticles under electromagnetic field  

Microsoft Academic Search

Magnetic nanoparticles have attracted increasingly attention due to their potential applications in many indus- trial fields, even extending their use in biomedical applications. In the latter contest the main features of magnetic nanoparticles are the possibility to be driven by external magnetic fields, the ability to pass through capillaries without occluding them and to absorb and convert electromagnetic radiation in

Giovanni Baldi; Giada Lorenzi; Costanza Ravagli

2009-01-01

100

Magnetic properties of polymer nanocomposites containing iron oxide nanoparticles  

Microsoft Academic Search

The magnetic behavior of polymer nanocomposites containing nanoparticles (?10nm) of oxidized magnetite in a polyvinyl alcohol matrix were investigated by means of Mossbauer transmission and conversion electron spectroscopy and magnetic measurements. The obtained results show that the base concentration of iron oxide nanoparticles within the polymer matrix volume greatly influences the magnetic properties of nanocomposites. The estimated lamellar distribution of

A. A. Novakova; V. Yu. Lanchinskaya; A. V. Volkov; T. S. Gendler; T. Yu. Kiseleva; M. A. Moskvina; S. B. Zezin

2003-01-01

101

Magnetic properties of polymer nanocomposites containing iron oxide nanoparticles  

Microsoft Academic Search

The magnetic behavior of polymer nanocomposites containing nanoparticles (~10nm) of oxidized magnetite in a polyvinyl alcohol matrix were investigated by means of Mossbauer transmission and conversion electron spectroscopy and magnetic measurements. The obtained results show that the base concentration of iron oxide nanoparticles within the polymer matrix volume greatly influences the magnetic properties of nanocomposites. The estimated lamellar distribution of

A. A. Novakova; V. Yu. Lanchinskaya; A. V. Volkov; T. S. Gendler; T. Yu. Kiseleva; M. A. Moskvina; S. B. Zezin

2003-01-01

102

Effects of Magnetic Nanoparticles in Smectic - A Liquid Crystals  

Microsoft Academic Search

We have observed the effects of adding magnetic nanoparticles with a different surface teminination to smectic A liquid crystals by examining the liquid crystals both with polarized optical microscopy and by X-ray scattering. Adding the magnetic nanoparticles improves the liquid crystal's response to a magnetic field by at least one to two orders of magnitude. Using different organic materials to

Luz J. Martinez-Miranda; Alexis Noel; Kevin McCarthy

2004-01-01

103

Chapter 11 magnetic nanoparticles in oxide glasses  

Microsoft Academic Search

Unique properties of the potassium-aluminum-boron glasses doped with low concentrations of MnO and Fe2O3 to make them magnetically ordered and optically transparent in the IR and visible ranges are due to the formation of nanoparticles\\u000a of a cubic ferrite. Assembling and properties of nanosized ferrite particles in the glasses have been investigated by X-ray\\u000a diffraction, differential dissolution analysis, high-resolution transmission

I. S. Edelman; R. D. Ivantsov; I. G. Vasil’eva; A. D. Vasil’ev; O. A. Bayukov; O. S. Ivanova; D. E. Prokof’ev; S. A. Stepanov; E. E. Kornilova; T. V. Zarubina; V. V. Malakhov; V. A. Zaikovskii

2006-01-01

104

Magnetic vectoring of magnetically responsive nanoparticles within the murine peritoneum  

NASA Astrophysics Data System (ADS)

Magnetically responsive nanoparticles (MNPs) might be candidates for pro-drug formulations for intraperitoneal (i.p.) treatment of ovarian cancer. We conducted feasibility experiments in an i.p. human ovarian carcinoma xenograft model to determine whether MNPs can be effectively vectored within this environment. Our initial results based on magnetic resonance imaging (MRI) indicate that i.p.-injected ˜15 nm magnetite-based MNPs can in fact migrate toward NdFeB magnets externally juxtaposed to the peritoneal cavity above the xenografts growing in the anterior abdominal wall. MNP localization to the tumor/peri-tumoral environment occurs. Further development of this MNP pro-drug strategy is underway.

Klostergaard, Jim; Bankson, James; Auzenne, Edmond; Gibson, Don; Yuill, William; Seeney, Charles E.

2007-04-01

105

Luminescent silicon nanoparticles with magnetic properties - production and investigation  

NASA Astrophysics Data System (ADS)

Silicon nanoparticles (nSi) with unusual properties were studied. After suggested treatment they became luminescent and also acquired a magnetic moment. Nanoparticles were prepared by laser pyrolysis of silane in a gas flow reactor followed by chemical treatment in methanol (MeOH) + HF + FeCl3 solution. After the treatment. nanoparticles gained stable luminescence with the peak position dependence on the excitation wavelength. With increasing of the excitation wavelength from 365 to 456 nm, the photoluminescent peak shifted from 632 to 665 nm. Luminescence of such nanoparticles had blue shift in comparison with the nanoparticles etched in widely-used solution for the silicon—MeOH + HF + HNO3. Moreover, after such treatment the magnetic moment of nanoparticles appeared, which is not inherent for the as-prepared nSi. Multifunctional silicon nanoparticles with both stable luminescence and magnetic moment at the same time are perspective for biology and medicine use as the optical and magnetic markers.

Kelm, E.; Korovin, S.; Pustovoy, V.; Surkov, A.; Vladimirov, A.

2011-11-01

106

Magnetostatic interactions between carbon nanotubes filled with magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

The magnetostatic interactions between carbon nanotubes filled with magnetic particles have been experimentally and theoretically studied. By making nanotubes uniformly magnetized, one eliminates the attraction caused by periodicity of nanoparticles in magnetic chains. The discreteness of individual nanoparticles in the nanoneedles is not observed and these nanoneedles interact by their magnetic poles. Since the attraction/repulsion events are predictable, the suspensions of magnetic nanotubes are attractive candidates for active elements in changeable diffraction gratings, filters, and polarizers.

Kornev, Konstantin G.; Halverson, Derek; Korneva, Guzeliya; Gogotsi, Yury; Friedman, Gary

2008-06-01

107

Biomedical tools based on magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic and superparamagnetic colloids represent a versatile platform for the design of functional nanostructures which may act as effective tools for biomedicine, being active in cancer therapy, tissue imaging and magnetic separation. The structural, morphological and hence magnetic features of the magnetic nanoparticles must be tuned for optimal perfomance in a given application. In this work, iron oxide nanocrystals have been prepared as prospective heat mediators in magnetic fluid hyperthermia therapy. A procedure based on the partial oxidation of iron (II) precursors in water based media has been adopted and the synthesis outcome has been investigated by X-Ray diffraction and Transmission electron microscopy. It was found that by adjusting the synthetic parameters (mainly the oxidation rate) magnetic iron oxide nanocrystals with cubic and cuboctahedral shape and average size 50 nm were obtained. The nanocrystals were tested as hyperthermic mediators through Specific Absorption Rate (SAR) measurements. The samples act as heat mediators, being able to increase the temperature from physiological temperature to the temperatures used for magnetic hyperthermia by short exposure to an alternative magnetic field and exhibit a reproducible temperature kinetic behavior.

Saba, Anna R.; Castillo, Paula M.; Fantechi, Elvira; Sangregorio, Claudio; Lascialfari, Alessandro; Sbarbati, Andrea; Casu, Alberto; Falqui, Andrea; Casula, Maria F.

2013-02-01

108

Ac magnetic susceptibility study of in vivo nanoparticle biodistribution  

NASA Astrophysics Data System (ADS)

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

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

2011-06-01

109

Encapsulation of magnetic and fluorescent nanoparticles in emulsion droplets.  

PubMed

Oils containing both fluorescent semiconductor and magnetic oxide nanoparticles are used to produce oil in water emulsions. This technique produces oil droplets with homogeneous fluorescence and high magnetic nanoparticle concentrations. The optical properties of the oil droplets are studied as a function of the droplet sizes for various concentrations of fluorescent and magnetic nanoparticles. For all concentrations tested, we find a linear variation of the droplet fluorescent intensity as a function of the droplet volume. For a given size and a given quantum dot (QD) concentration, the droplet fluorescence intensity drops sharply as a function of the magnetic nanoparticle concentration. We show that this decrease is due mainly to the strong absorption cross section of the magnetic nanoparticles and to a lesser extent to the dynamic and static quenching of the QD fluorescence. The role of the iron oxide nanoparticle localization in the droplet (surface versus volume) is also discussed. PMID:15835991

Mandal, Swapan K; Lequeux, Nicolas; Rotenberg, Benjamin; Tramier, Marc; Fattaccioli, Jacques; Bibette, Jerome; Dubertret, Benoit

2005-04-26

110

Clinical and laboratory evaluation of the antibody-coated bacteria test in children.  

PubMed

The antibody-coated bacteria test can distinguish upper from lower urinary tract infection. In this study 67 bacteriuric children were selected from meningomyelocele and urology clinics. There was close correlation between radiological evidence of upper tract changes and the presence of antibody-coated bacteria. There was a distinct lack of correlation between serum antibody titers to the infecting organism and antibody-coated bacteria. In vitro laboratory studies indicated that 1) antibody coating in the urine occurred immediately upon exposure of the infecting isolate to the urine of the patient, 2) only the homologous isolate was coated and 3) the pH range for antibody coating was wide (pH 4.0 to 9.0). PMID:35625

Kwasnik, I; Klauber, G; Tilton, R C

1979-05-01

111

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.

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

2009-01-01

112

Magnetic domain formation in monolayer nanoparticle films  

NASA Astrophysics Data System (ADS)

Self-assembled magnetic nanoparticle films offer promise as data storage media, but an understanding of the interactions is missing. Modified Langmuir-Blodgett methods were used to prepare monolayer films of 7 and 11 nm diameter Fe3O4 nanoparticles with large structural domains. Small-angle neutron scattering (SANS) shows a peak at a wavevector Q corresponding to the particle size and spacing, and scattering at intermediate Q indicating possible long-range correlations. We extend to lower Q with off-specular neutron reflectivity, achieving high intensity by sacrificing resolution along one in-plane direction y while retaining high resolution in the other in-plane direction x and the normal direction z. We measure in saturation and zero field to extract magnetic scattering. In high fields, the specular scattering (Qx=0) is increased, consistent with aligned moments. Preliminary results show weak magnetic scattering for nonzero Qx . Since the maximal Qx roughly corresponds to the lowest Q in SANS, the combination of these techniques allows us to quantify field-dependent magnetic domain size.

Maranville, Brian; Krycka, Kathryn; Borchers, Julie; Hogg, Charles; Majetich, Sara; Ijiri, Yumi

2009-03-01

113

Synthesis of Polyethylene Magnetic Nanoparticles  

Microsoft Academic Search

Very low molecular weight polyethylene (average MW 700?g\\/mole) magnetic nanocomposite particles were synthesized by nonsolvent and temperature induced crystallization along with ultrasonication. The particles are further coated with poly dl-lactic acid to functionalize the polyethylene particles for biomedical applications. A solvent-nonsolvent emulsion was made with polyethylene and surface modified iron oxide and was raised to very high temperature followed by

Jhunu Chatterjee; Yousef Haik; Ching-Jen Chen

2002-01-01

114

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

115

Magnetic Nanoparticles for Manipulation and Control of Biological Processes.  

National Technical Information Service (NTIS)

We explored the potential of magnetic nanoparticles (MNPs) for manipulation and control of cell functions using magnetic fields. We synthesized several types of MNPs, functionalize their surfaces to make them biocompatible, and bind them to cells. The inv...

L. J. Martinez-Miranda S. H. Ehrman T. R. Pulliam-Holoman S. Majetich G. Majetich

2004-01-01

116

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

117

A solid state nanopore device for investigating the magnetic properties of magnetic nanoparticles.  

PubMed

In this study, we explored magnetic nanoparticles translocating through a nanopore in the presence of an inhomogeneous magnetic field. By detecting the ionic current blockade signals with a silicon nitride nanopore, we found that the translocation velocity that is driven by magnetic and hydrodynamic forces on a single magnetic nanoparticle can be accurately determined and is linearly proportional to the magnetization of the magnetic nanoparticle. Thus, we obtained the magneto-susceptibility of an individual nanoparticle and the average susceptibility over one hundred particles within a few minutes. PMID:23708272

Park, SangYoon; Lim, Jaekwan; Pak, Y Eugene; Moon, Seunghyun; Song, Yoon-Kyu

2013-05-24

118

A Solid State Nanopore Device for Investigating the Magnetic Properties of Magnetic Nanoparticles  

PubMed Central

In this study, we explored magnetic nanoparticles translocating through a nanopore in the presence of an inhomogeneous magnetic field. By detecting the ionic current blockade signals with a silicon nitride nanopore, we found that the translocation velocity that is driven by magnetic and hydrodynamic forces on a single magnetic nanoparticle can be accurately determined and is linearly proportional to the magnetization of the magnetic nanoparticle. Thus, we obtained the magneto-susceptibility of an individual nanoparticle and the average susceptibility over one hundred particles within a few minutes.

Park, SangYoon; Lim, Jaekwan; Pak, Y. Eugene; Moon, Seunghyun; Song, Yoon-Kyu

2013-01-01

119

Magnetism of cluster-deposited Y-Co nanoparticles  

SciTech Connect

Nanoparticles of YCo{sub 2}, YCo{sub 3}, and YCo{sub 5} are produced by cluster-deposition and investigated bothstructurally and magnetically. The nanoparticles have sizes of less than 10 nm and aresuperparamagnetic at 300 K, irrespective of stoichiometry. As-produced nanoparticles exhibitdisordered structures with magnetic properties differing from those of the bulk particles.The temperature-dependent magnetization curves of the nanoparticles reveal blocking temperatures from 110 to 250 K, depending on stoichiometry. The magnetic anisotropy constant K{sub 1}of disordered YCo{sub 5} nanoparticles of 7.8 nm in size is 3.5 x 10{sup 6} ergs/cm{sup 3}, higher than those of thedisordered YCo{sub 2} (8.9 x 10{sup 5} ergs/cm{sup 3}) and YCo{sub 3} (1.0 x 10{sup 6} ergs/cm{sup 3}) nanoparticles.

Balamurugan, B.; Skomski, R.; Sellmyer, D. J. [Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE 68588 (United States); Department of Physics and Astronomy, University of Nebraska, Lincoln, NE 68588 (United States); Li, X. Z.; Shah, V. R. [Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE 68588 (United States); Hadjipanayis, G. C. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Shield, J. E. [Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE 68588 (United States); Department of Mechanical Engineering, University of Nebraska, Lincoln, NE 68588 (United States)

2011-04-01

120

Preparation and application of silica-coated magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Silica coated magnetic nanoparticles have been prepared by sign water-in-oil micro emulsion technique, and have been characterized by Transmission Electron Microscopy and e-ray diffractometer. Concanavalin A was covalent immobilized on the surface of silica coated magnetic nanoparticles. Dextran-Rhodamine B could be easily separated from aqueous solutions by the functionalized nanoparticles. The result implied that the preparation route is easy to yield silica coated magnetic nanoparticles which can be modified for the separation of other target biomolecules, cells, and etc.

He, Xiaoxiao; Wang, Kemin; Tan, Weihong; Xiao, Dan; Yang, Xiaohai; Li, Jun

2001-09-01

121

Magnetoacoustic imaging of magnetic iron oxide nanoparticles embedded in biological tissues with microsecond magnetic stimulation  

PubMed Central

We present an experimental study on magnetoacoustic imaging of superparamagnetic iron oxide (SPIO) nanoparticles embedded in biological tissues. In experiments, a large-current-carrying coil is used to deliver microsecond pulsed magnetic stimulation to samples. The ultrasound signals induced by magnetic forces on SPIO nanoparticles are measured by a rotating transducer. The distribution of nanoparticles is reconstructed by a back-projection imaging algorithm. The results demonstrated the feasibility to obtain cross-sectional image of magnetic nanoparticle targets with faithful dimensional and positional information, which suggests a promising tool for tomographic reconstruction of magnetic nanoparticle-labeled diseased tissues (e.g., cancerous tumor) in molecular or clinic imaging.

Hu, Gang; He, Bin

2012-01-01

122

Magnetic nanoparticles for biomedical NMR-based diagnostics  

PubMed Central

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

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

2010-01-01

123

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

124

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

125

Preparation of magnetic polymeric composite nanoparticles by seeded emulsion polymerization  

Microsoft Academic Search

Seeded emulsion polymerization was used to prepare magnetic polymeric composite nanoparticles (MPCNPs) with the aim to successfully encapsulate magnetite particles and to improve particle size distribution (PSD). Microscopical morphology and number-average diameter of hydrophilic magnetite particles (HMPs), magnetic seed latex nanoparticles (MSLNPs) and MPCNPs were observed and analyzed by transmission electron microscope (TEM). Weight-average diameter and PSD of MSLNPs and

Shulai Lu; Rongjun Qu; Jacqueline Forcada

2009-01-01

126

Applications of Magnetic Micro and Nanoparticles in Biology and Medicine  

Microsoft Academic Search

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

J. Dobson

2005-01-01

127

Photo-Switching of Magnetization in Iron Nanoparticles  

NASA Astrophysics Data System (ADS)

We report the theoretical studies of light induced switching in core-shell nanoparticles. The core of the nanoparticle is made of Fe coated with the shell of azobenzene. The latter is a photochromic material with the reversible trans-cis photoisomerization upon irradiation by UV and visible light. The magnetization of nanoparticles can be reversibly switched by using specific wavelengths of light. trans-cis photoisomerization of azobenzene induces both the change in surface local magnetic moments and alters the exchange interactions on the surfaces of the nanoparticles. These two mechanisms can lead to induced magnetization switchable by light pulse. We study the effects of photoisomerization of azobenzene on iron (Fe) nanoparticle. Ab initio calculations using SIESTA code show that the ferromagnetic (FM) and antiferromagnetic (AFM) exchange interaction in Fe dimer increase by 40% due to photoisomerization of azobenzene. While an infinite flat Fe monolayer shows variation on the exchange interactions on the surfaces as result of photoisomerization. The local magnetic moments of Fe sheet increase by 6% due to photoisomerization. Using an ab initio parameterization of magnetic interactions, we propose statistical model based on competing exchange interactions for the investigation of Fe nanoparticle magnetization. We performed Monte Carlo simulations of magnetization of the core-shell nanoparticle as a function of temperature. The results show that Fe nanoparticles magnetization at room temperature can change by at least 40% due to photoisomerization of azobenzene.

Al-Aqtash, Nabil; Hostetter, Alexander; Sabirianov, Renat

2012-02-01

128

Magnetic nanoparticles as targeted delivery systems in oncology  

PubMed Central

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

Prijic, Sara; Sersa, Gregor

2011-01-01

129

Fe-based nanoparticles as tunable magnetic particle hyperthermia agents  

NASA Astrophysics Data System (ADS)

Magnetic hyperthermia, an alternative anticancer modality, is influenced by the composition, size, magnetic properties, and degree of aggregation of the corresponding nanoparticle heating agents. Here, we attempt to evaluate the AC magnetic field heating response of Fe-based nanoparticles prepared by solar physical vapor deposition, a facile, high-yield methodology. Nanoparticle systems were grown by evaporating targets of Fe and Fe3O4 with different stoichiometry. It is observed that Fe3O4 nanoparticles residing in the magnetic monodomain region exhibit increased heating efficiency together with high specific loss power values above 0.9 kW/g at 765 kHz and 24 kA/m, compared with that of 0.1 kW/g for zero-valent Fe nanoparticles under the same conditions. The enhanced performance of Fe3O4 nanoparticles under the range of field explored (12-24 kA/m) may be attributed to the activation of a magnetic hysteresis loss mechanism when the applied AC field surpasses the particle anisotropy field at H >= 0.5HA. This is also illustrated by the smaller coercivity of Fe3O4 nanoparticles compared with that of their Fe counterparts. Therefore, understanding the interconnection between intrinsic parameters (composition, size and magnetic properties), the dosage (concentration, volume) and the intensity and frequency of the AC field can lead to essential design guidelines for in vitro, in vivo, and clinical applications of magnetic nanoparticles for hyperthermia.

Simeonidis, K.; Martinez-Boubeta, C.; Balcells, Ll.; Monty, C.; Stavropoulos, G.; Mitrakas, M.; Matsakidou, A.; Vourlias, G.; Angelakeris, M.

2013-09-01

130

TOPICAL REVIEW: Applications of magnetic nanoparticles in biomedicine  

Microsoft Academic Search

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

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

2003-01-01

131

Local Control of Ultrafast Dynamics of Magnetic Nanoparticles  

SciTech Connect

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

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

2009-02-06

132

Imaging the Distribution of Magnetic Nanoparticles With Ultrasound  

Microsoft Academic Search

Magnetic nanoparticles can be caused to oscillate under the influence of an incident ultrasonic wave. If the particles are momentarily aligned with a magnetizing pulse creating a macroscopic magnetization, this oscillation will result in a time-varying magnetic moment which should be detectable as an induced voltage in a nearby pickup coil. In this way, focused ultrasound can be used to

Stephen J. Norton; Tuan Vo-Dinh

2007-01-01

133

Magnetic nanoparticles for applications in oscillating magnetic field  

SciTech Connect

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

Peeraphatdit, Chorthip

2010-12-15

134

A Renewable Electrochemical Magnetic Immunosensor Based on Gold Nanoparticle Labels  

SciTech Connect

A particle-based renewable electrochemical magnetic immunosensor was developed by using magnetic beads and a gold nanoparticle label. Anti-IgG antibody-modified magnetic beads were attached to a renewable carbon paste transducer surface by magnets that were fixed inside the sensor. A gold nanoparticle label was 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 tracer and avoid the use of an enzyme label and substrate. The stripping signal of gold nanoparticle 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 ?g ml-1of 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.

Liu, Guodong; Lin, Yuehe

2005-05-24

135

High efficiency protein separation with organosilane assembled silica coated magnetic nanoparticles  

Microsoft Academic Search

This work describes the development of high efficiency protein separation with functionalized organosilanes on the surface of silica coated magnetic nanoparticles. The magnetic nanoparticles were synthesized with average particle size of 9 nm and silica coated magnetic nanoparticles were obtained by controlling the coating thicknesses on magnetic nanoparticles. The silica coating thickness could be uniformly sized with a diameter of

Jeong Ho Chang; Ki Ho Kang; Jinsub Choi; Young Keun Jeong

2008-01-01

136

Intracellular Confinement of Magnetic Nanoparticles by Living Cells: Impact for Imaging and Therapeutic Applications  

Microsoft Academic Search

Superparamagnetic properties of iron-oxide nanoparticles paved the way for various biomedical applications, such as magnetic resonance imaging (MRI), magnetic targeting of drug vectors or magnetically-induced therapeutic hyperthermia. Living cells interact with nanoparticles by internalizing them within intracellular compartments, called lysosomes. In the course of cellular uptake, the spatial distribution of magnetic nanoparticles changes from dilute isolated nanoparticles to a highly

Florence Gazeau; Michael Lévy; Claire Wilhelm

2011-01-01

137

Synthesis and Characterisation of Pure Cobalt Magnetic Nanoparticle by Metal Reduction  

Microsoft Academic Search

The study of nanoparticles magnet domains is of both fundamental and pressing technical interest as the magnetic properties depend strongly on grain size. Comparing magnetic properties of pure metal nanoparticles with different grain sizes will visualise the steps needed to form monodispersed magnetic nanoparticles. In this paper, the synthesis of Cobalt (Co) nanoparticles by metal salts reduction using cobalt chloride

N. H. Nordin; Y. S. Neo; B. H. Ong

2009-01-01

138

Temperature dependent coercivity and magnetization of nickel ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles of nickel ferrite (size: 24±4 nm) have been synthesized by chemical coprecipitation method using stable ferric and nickel salts. Coercivity of nanoparticles has been found to increase with decrease in temperature of the samples. It has been observed that the coercivity follows a simple model of thermal activation of particle’s moment over the anisotropy barrier in the temperature range (10-300 K), in accordance with Kneller’s law for ferromagnetic materials. Saturation magnetization follows the modified Bloch’s law in the temperature range from 300 to 50 K. However, below 50 K, an abrupt increase in magnetization of nanoparticles was observed. This increase in magnetization at lower temperatures was explained with reference to the presence of freezed surface-spins and some paramagnetic impurities at the shell of nanoparticles that are activated at lower temperatures in core-shell nickel ferrite nanoparticles.

Maaz, K.; Mumtaz, A.; Hasanain, S. K.; Bertino, M. F.

2010-08-01

139

Promising iron oxide-based magnetic nanoparticles in biomedical engineering.  

PubMed

For the past few decades biomedical engineering has imprinted its significant impact on the map of science through its wide applications on many other fields. An important example obviously proving this fact is the versatile application of magnetic nanoparticles in theranostics. Due to preferable properties such as biocompatibility, non-toxicity compared to other metal derivations, iron oxide-based magnetic nanoparticles was chosen to be addressed in this review. Aim of this review is to give the readers a whole working window of these magnetic nanoparticles in the current context of science. Thus, preparation of magnetic iron oxide nanoparticles with the so-far techniques, methods of characterizing the nanoparticles as well as their most recent biomedical applications will be stated. PMID:23263800

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

2012-12-21

140

Spectral-domain magnetomotive OCT imaging of magnetic nanoparticle biodistribution  

NASA Astrophysics Data System (ADS)

Magnetomotive optical coherence tomography (MMOCT) is a method for imaging the distribution of magnetic nanoparticles in tissue by applying an external dynamic magnetic field gradient during B-mode scanning. We present a new method for spectral-domain MMOCT imaging which affords increased sensitivity and frame rates compared to previous work, with a demonstrated sensitivity to <100 ppm iron oxide nanoparticles and imaging time of 5 s. Agarose phantoms embedded with iron oxide nanoparticles (~20 nm) also provide negative T2 contrast in magnetic resonance imaging (MRI) with sensitivity <10 ppm, which is promising for multi-modality applications where MRI and MMOCT provide whole-body and microscopic imaging, respectively. To demonstrate the biomedical potential of this technique, rats are injected with the same nanoparticles as those used in MRI, and uptake into the spleen is detected and imaged post mortem by MMOCT. This illustrates a potentially powerful multi-modal platform for molecular imaging using targeted magnetic nanoparticles.

Oldenburg, Amy L.; Crecea, Vasilica; Rinne, Stephanie A.; Rezaeipoor, Robabeh; Chaney, Eric J.; Boppart, Stephen A.

2008-03-01

141

The effects of magnetic nanoparticle properties on magnetic fluid hyperthermia  

NASA Astrophysics Data System (ADS)

Magnetic fluid hyperthermia (MFH) is a noninvasive treatment that destroys cancer cells by heating a ferrofluid-impregnated malignant tissue with an ac magnetic field while causing minimal damage to the surrounding healthy tissue. The strength of the magnetic field must be sufficient to induce hyperthermia but it is also limited by the human ability to safely withstand it. The ferrofluid material used for hyperthermia should be one that is readily produced and is nontoxic while providing sufficient heating. We examine six materials that have been considered as candidates for MFH use. Examining the heating produced by nanoparticles of these materials, barium-ferrite and cobalt-ferrite are unable to produce sufficient MFH heating, that from iron-cobalt occurs at a far too rapid rate to be safe, while fcc iron-platinum, magnetite, and maghemite are all capable of producing stable controlled heating. We simulate the heating of ferrofluid-loaded tumors containing nanoparticles of the latter three materials to determine their effects on tumor tissue. These materials are viable MFH candidates since they can produce significant heating at the tumor center yet maintain the surrounding healthy tissue interface at a relatively safe temperature.

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

2010-11-01

142

Bacterial Magnetic Nanoparticles as Peroxidase Mimetics and Application in Immunoassay  

Microsoft Academic Search

Although progress in nanosynthesis has succeeded in making nanoscale particles from iron oxide, the research about natural magnetic nanoparticles, magnetosomes, is still a current interest because of their intrinsic magnetic features, nano-features, membrane-enclosed features and genetic control of size and morphology properties. In this study, we investigated magnetosomes' intrinsic peroxidase-like activity similar to that found in artificial magnetic nanoparticles. We

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

2010-01-01

143

Immobilization of biomolecules on biotinylated magnetic ferrite nanoparticles  

Microsoft Academic Search

We have developed biocompatible ferrite (Fe3O4) nanoparticles whose surfaces are functionalized with biotin molecule. The resulting magnetic nanoparticles with an average diameter of 8nm have a biotin-anchored morphology, which gives an exceptionally high affinity for the Cy3-labeled streptavidin. The spectroscopic and magnetic data results confirmed the presence of the interaction between biotin-anchored Fe3O4 particles and Cy3-labeled streptavidins. These biocompatible magnetic

Jungkweon Choi; Jong In Lee; Yong Bok Lee; Jung Hoon Hong; In Seon Kim; Yong Ki Park; Nam Hwi Hur

2006-01-01

144

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

145

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

Microsoft Academic Search

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

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

2009-01-01

146

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

147

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

NASA Astrophysics Data System (ADS)

A great deal of attention has been paid to the use of magnetite nanoparticles as heating elements in the research of magnetic fluid hyperthermia. However, these particles have a relatively low magnetization and as a result, have low heating efficiency as well as difficulties in detection applications. To maximize heating efficiency we propose and show the use of high-moment Fe(Co)-Au core-shell nanoparticles. Using a physical vapor nanoparticle-deposition technique the high-moment nanoparticles were synthesized. The water-soluble particles were placed in an AC magnetic field of variable magnetic field frequencies. The temperature rise was measured and compared to theory.

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

2009-05-01

148

Polymer Janus particles containing block-copolymer stabilized magnetic nanoparticles.  

PubMed

In this report, we show a simple route to fabricate Janus particles having magnetic nanoparticles inside them, which can respond and rotate along to magnetic fields. By solvent evaporation from the tetrahydrofran solution of polymer stabilized ?-Fe2O3 nanoparticles, polystyrene (PS), and polyisoprene containing water, aqueous dispersion of Janus microparticles were successfully prepared, and the ?-Fe2O3 nanoparticles were selectively introduced into the PS phase. We demonstrate rotation and accumulation of Janus particles by using a neodymium magnet. PMID:23480421

Yabu, Hiroshi; Kanahara, Masaaki; Shimomura, Masatsugu; Arita, Toshihiko; Harano, Koji; Nakamura, Eiichi; Higuchi, Takeshi; Jinnai, Hiroshi

2013-04-02

149

Inhalable magnetic nanoparticles for targeted hyperthermia in lung cancer therapy.  

PubMed

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

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

2013-04-13

150

Advanced magnetic anisotropy determination through isothermal remanent magnetization of nanoparticles  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

151

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.

Mamiya, Hiroaki; Jeyadevan, Balachandran

2011-01-01

152

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

NASA Astrophysics Data System (ADS)

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.

Mamiya, Hiroaki; Jeyadevan, Balachandran

2011-11-01

153

Magnetic characterization of superparamagnetic nanoparticles pulled through model membranes  

PubMed Central

Background To quantitatively compare in-vitro and in vivo membrane transport studies of targeted delivery, one needs characterization of the magnetically-induced mobility of superparamagnetic iron oxide nanoparticles (SPION). Flux densities, gradients, and nanoparticle properties were measured in order to quantify the magnetic force on the SPION in both an artificial cochlear round window membrane (RWM) model and the guinea pig RWM. Methods Three-dimensional maps were created for flux density and magnetic gradient produced by a 24-well casing of 4.1 kilo-Gauss neodymium-iron-boron (NdFeB) disc magnets. The casing was used to pull SPION through a three-layer cell culture RWM model. Similar maps were created for a 4 inch (10.16 cm) cube 48 MGOe NdFeB magnet used to pull polymeric-nanoparticles through the RWM of anesthetized guinea pigs. Other parameters needed to compute magnetic force were nanoparticle and polymer properties, including average radius, density, magnetic susceptibility, and volume fraction of magnetite. Results A minimum force of 5.04 × 10-16 N was determined to adequately pull nanoparticles through the in-vitro model. For the guinea pig RWM, the magnetic force on the polymeric nanoparticles was 9.69 × 10-20 N. Electron microscopy confirmed the movement of the particles through both RWM models. Conclusion As prospective carriers of therapeutic substances, polymers containing superparamagnetic iron oxide nanoparticles were succesfully pulled through the live RWM. The force required to achieve in vivo transport was significantly lower than that required to pull nanoparticles through the in-vitro RWM model. Indeed very little force was required to accomplish measurable delivery of polymeric-SPION composite nanoparticles across the RWM, suggesting that therapeutic delivery to the inner ear by SPION is feasible.

Barnes, Allison L; Wassel, Ronald A; Mondalek, Fadee; Chen, Kejian; Dormer, Kenneth J; Kopke, Richard D

2007-01-01

154

[Bio-detection techniques based on magnetic signal of nanoparticles].  

PubMed

This article summarizes biological detection techniques based on magnetic signal of magnetic nanoparticles and the research progress of these techniques in biomedicine. Biological detection based on magnetic nanoparticles is faster, more accurate and more convenient compared to traditional optical techniques and causes much attention. It can be classified into giant magneto resistive biosensor (GMR), magnetic relaxation switch (based on T2 relaxation time), AC susceptibility (based on Brownian relaxation) and magnetic lateral flow immunoassay. These techniques can be combined with nanotechnology, microfluidics, immunoassay and bio-chips and have wide application prospects in clinical diagnosis, biological detection, environmental monitoring and food security areas. PMID:24059074

Yin, Shi; Gu, Hongchen; Xu, Hong

2013-08-01

155

Magnetic order in two-dimensional nanoparticle assemblies  

NASA Astrophysics Data System (ADS)

This thesis involves a fundamental study of two-dimensional arrays of magnetic nanoparticles using non-contact Atomic Force Microscopy, Magnetic Force Microscopy, and Atomic Force Spectroscopy. The goal is to acquire a better understanding of the interactions between magnetic nanoparticles and the resulting configuration of their magnetic moments. We have studied two systems: 20-nm magnetite (Fe3O4) and 21-nm cobalt ferrite (CoFe2O4) nanoparticles, capped with oleic acid and oleylamine, deposited using drop-casting technique on HOPG (Highly Oriented Pyrolytic Graphite). We present an analytical model to interpret the experimental spectroscopy curves (frequency shift as a function of the tip-sample distance) in terms of force, to enable a quantitative interpretation of the experimental results. In addition, a numerical model based on the Metropolis Monte Carlo method has been developed to calculate the configuration of magnetic moments with minimum energy. The energy consists of dipolar energy and anisotropy energy. The simulations have shown that local energy minima are present that correspond to different configurations of magnetic moments. Because of the thermal energy, the system may jump in between these energy minima. Considering a specific configuration of moments, MFM images were simulated taking the dipolar interactions between the nanoparticles and the tip into account. Spectroscopy curves were calculated for two cases: namely with and without the influence of the tip. The magnetite nanoparticles present a relatively large magnetic moment and exhibit strong dipole-dipole interactions and small, negligible, anisotropy. The observed repulsion between the tip and the nanoparticles at the side of the nanoparticle islands shows that dipolar coupling between the particles causes blocking of their magnetic moments. The experimental observations agree well with the numerical calculations, which show that the magnetic moments arrange themselves in flux-closure structures. However, the magnetite nanoparticle 2D systems can be considered soft-magnetic: their moments are strongly influenced by the field of the tip. This has been observed experimentally and confirmed by simulations for the considered magnetic moment of the tip. The cobalt-ferrite nanoparticles present a similar magnetic moment as the magnetite nanoparticles. The anisotropy, however, increases significantly with decreasing temperature, which leads to blocking of the moments even in the strong field of the tip. As a consequence, attractive and repulsive areas were observed in the MFM image above the islands of nanoparticles at low temperatures. In our simulation we have assumed arbitrary orientations of the easy axes of the particles. Simulation results reveal short-range order of the magnetic moments, consistent with the experimental results.

Georgescu, M.

2008-12-01

156

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.

157

Preparation and characterization of fluorescent silica coated magnetic hybrid nanoparticles  

Microsoft Academic Search

In this report we describe the synthesis, characterization of fluorescent silica coated magnetic hybrid nanoparticles. These nanoparticles have been synthesized by combining the co-precipitation, polymerization and sol–gel technology with fluorescent dye. And their size can range from about 80 to 90nm in diameter. The nanoparticles were characterized by atomic force microscopy (AFM), fourier transform infrared (FTIR) spectroscopy, spectrofluorometer, X-ray diffraction

Kaliyaperumal Viswanathan

2011-01-01

158

Preparation of magnetic nanoparticles by pulsed plasma chemical vapor synthesis  

Microsoft Academic Search

FePt nanoparticle is expected as a candidate for the magnetic material of the high density recording media. We attempted to synthesize FePt alloy nanoparticles using 13.56 MHz glow discharge plasma with the pulse operation of a square-wave on\\/off cycle of plasma discharge to control the size of nanoparticles. Vapors of metal organics, Biscyclopentadienyl iron (ferrocene) for Fe and (Methylcyclopentadienyl) trimethyl platinum

I. Matsui

2006-01-01

159

Microwave Cancer Imaging Exploiting Magnetic Nanoparticles as Contrast Agent  

Microsoft Academic Search

In this paper, a microwave technique for breast cancer imaging is presented. The approach is based on the use of magnetic nanoparticles as contrast agent to induce a nonnull magnetic con- trast selectively localized within the tumor. This allows us to face cancer imaging as the reconstruction of a magnetic contrast from the corresponding scattered field. To extract, from the

Gennaro Bellizzi; Ovidio M. Bucci; Ilaria Catapano

2011-01-01

160

Fluid Dynamics of Magnetic Nanoparticles in Simulated Blood Vessels  

Microsoft Academic Search

Magnetic nanoparticles (MNPs) can be used to locally target therapies and offer the benefit of using an AC magnetic field to combine hyperthermia treatment with the triggered release of therapeutic agents. Here, we investigate localization of MNPs in a simulated environment to understand the relationship between magnetic field intensity and bulk fluid dynamics to determine MNP retention in a simulated

Lauren Blue; Mary Kathryn Sewell; Christopher S. Brazel

2008-01-01

161

Progress in applications of magnetic nanoparticles in biomedicine  

Microsoft Academic Search

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

Q A Pankhurst; NKT Thanh; J Dobson

2009-01-01

162

Synthesis and characterization of polymer nanocomposites containing magnetic nanoparticles  

Microsoft Academic Search

Magnetic poly(methyl methacrylate) nanocomposites were prepared using oleic acid coated cobalt ferrite and magnetite nanoparticles. Both nanofillers had a similar effect in shifting the glass transition temperature from that of the neat polymer. The cobalt ferrite nanocomposite had magnetic hysteresis at 2 and 300 K and the magnetite nanocomposite had magnetic hysteresis at 2 K and superparamagnetic behavior at 300

Edwin de La Cruz-Montoya; Carlos Rinaldi

2010-01-01

163

Noninvasive assessment of magnetic nanoparticle-cancer cell interactions  

PubMed Central

The success of magnetic nanoparticle (mNP)-based diagnostic and therapeutic techniques is dependent upon how the mNP are distributed in vivo. The potential efficacy and timing of a given magnetic nanoparticle treatment or diagnostic test is largely determined by the number of nanoparticles in each tissue and microscopic compartment: e.g., in the intravascular and extravascular spaces, in the interstitial space, cell surface and in cell cytoplasm. Techniques for monitoring these cell-level interactions generally require the harvesting and destruction of tissues or cells at each time point of interest. We present a method (magnetic spectroscopy of Brownian motion, MSB) for longitudinally monitoring nanoparticle binding to cell surface proteins and uptake by cancer cells in vitro using the harmonics of the magnetization produced by the nanoparticles. These harmonics can be measured rapidly and noninvasively without the need for nanoparticle modifications and without damaging the cells. We demonstrate sensitivity of this harmonic signal to the nanoparticles’ microenvironment and use this technique to monitor the nanoparticle binding activities of different cell lines.

Giustini, Andrew J.; Perreard, Irina; Rauwerdink, Adam M.; Hoopes, P. Jack; Weaver, John B.

2012-01-01

164

Magnetic properties of carbon stabilized multiferroic bismuth ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Carbon-stabilized bismuth ferrite (BiFeO3) nanoparticles have been synthesized by a self-combustion method, under ambient conditions and post annealing at selective temperatures between 400-800°C in air. BiFeO3 nanoparticles in carbon matrix show enhanced magnetic properties compared to its bulk counterpart.

Karan, T.; Ram, S.; Kotnala, R. K.

2012-06-01

165

Functional nanocomposite polymer films with uniform magnetic nanoparticle dispersions  

Microsoft Academic Search

Magnetic nanoparticles embedded in polymer matrices are good examples of functional nanostructures with excellent potential in applications such as tunable microwave devices, EMI shielding, and flexible electronics. The challenge comes with evenly dispersing the nanoparticles once they are embedded in the polymer matrix. To avoid clustering of particles in the polymer nanocomposites and achieve excellent dispersion, competition between polymer-polymer and

K. Stojak; S. Pal; M. J. Miner; H. Srikanth; S. Skidmore; J. Wang; T. Weller

2009-01-01

166

Synthesis and characterization of magnetic nanoparticles for use as sensors  

Microsoft Academic Search

A comprehensive study of physical and magnetic properties of cobalt substituted ferrite and magnetite nanoparticles synthesized by thermal-decomposition was carried out. Initially, a systematic study of the effect of synthesis conditions on final size, crystalline structure, and composition of cobalt substituted ferrite nanoparticles synthesized by thermal-decomposition was carried out. Using a statistical design of experiments, the impact of the temperature

Victoria L. Calero Diaz Del Castillo

2009-01-01

167

Synthesis of surface functionalized magnetic nanoparticles and their polymer nanocomposites  

Microsoft Academic Search

Magnetic nanoparticles embedded in polymer matrices are good examples of functional nanostructures with excellent potential in applications such as tunable microwave devices, EMI shielding, flexible electronics etc. Control over the dispersion of the nanoparticle phase embedded in a polymer matrix is critical and often challenging. To achieve excellent dispersion, competition between polymer-polymer and polymer-particle interactions must be balanced to avoid

M. J. Miner; M. B. Morales; P. Poddar; H. Srikanth; S. M. Skidmore; T. M. Weller

2008-01-01

168

Tailored Magnetic Nanoparticles for Optimizing Magnetic Fluid Hyperthermia  

PubMed Central

Magnetic Fluid Hyperthermia (MFH) is a promising approach towards adjuvant cancer therapy that is based on the localized heating of tumors using the relaxation losses of iron oxide magnetic nanoparticles (MNPs) in alternating magnetic fields (AMF). In this study, we demonstrate optimization of MFH by tailoring MNP size to an applied AMF frequency. Unlike conventional aqueous synthesis routes, we use organic synthesis routes that offer precise control over MNP size (diameter ~ 10–25 nm), size distribution and phase purity. Furthermore, the particles are successfully transferred to the aqueous phase using a biocompatible amphiphilic polymer, and demonstrate long-term shelf life. A rigorous characterization protocol ensures that the water-stable MNPs meet all the critical requirements: (1) uniform shape and monodispersity, (2) phase purity, (3) stable magnetic properties approaching that of the bulk, (4) colloidal stability, (5) substantial shelf life and (6) pose no significant in vitro toxicity. Using a dedicated hyperthermia system, we then identified that 16 nm monodisperse MNPs (? ~ 0.175) respond optimally to our chosen AMF conditions (f = 373 kHz, Ho = 14 kA/m); however, with a broader size distribution (? ~ 0.284) the Specific Loss Power (SLP) decreases by 30%. Finally, we show that these tailored MNPs demonstrate maximum hyperthermia efficiency by reducing viability of Jurkat cells in vitro, suggesting our optimization translates truthfully to cell populations. In summary, we present a way to intrinsically optimize MFH by tailoring the MNPs to any applied AMF, a required precursor to optimize dose and time of treatment.

Khandhar, Amit; Ferguson, R. Matthew; Simon, Julian A.; Krishnan, Kannan M.

2011-01-01

169

Targeting to carcinoma cells with chitosan- and starch-coated magnetic nanoparticles for magnetic hyperthermia.  

PubMed

The delivery of hyperthermic thermoseeds to a specific target site with minimal side effects is an important challenge in targeted hyperthermia, which employs magnetic method and functional polymers. An external magnetic field is used to control the site-specific targeting of the magnetic nanoparticles. Polymer-coated magnetic nanoparticles can confer a higher affinity to the biological cell membranes. In this study, uncoated, chitosan-coated, and starch-coated magnetic nanoparticles were synthesized for use as a hyperthermic thermoseed. Each sample was examined with respect to their applications to hyperthermia using XRD, VSM, and FTIR. In addition, the temperature changes under an alternating magnetic field were observed. As in vitro tests, the magnetic responsiveness of chitosan- and starch-coated magnetite was determined by a simple blood vessel model under various intensities of magnetic field. L929 normal cells and KB carcinoma cells were used to examine the cytotoxicity and affinity of each sample using the MTT method. The chitosan-coated magnetic nanoparticles generated a higher DeltaT of 23 degrees C under an AC magnetic field than the starch-coated magnetite, and the capturing rate of the particles was 96% under an external magnetic field of 0.4 T. The highest viability of L929 cells was 93.7%. Comparing the rate of KB cells capture with the rate of L929 cells capture, the rate of KB cells capture relatively increased with 10.8% in chitosan-coated magnetic nanoparticles. Hence, chitosan-coated magnetic nanoparticles are biocompatible and have a selective affinity to KB cells. The targeting of magnetic nanoparticles in hyperthermia was improved using a controlled magnetic field and a chitosan-coating. Therefore, chitosan-coated magnetic nanoparticles are expected to be promising materials for use in magnetic targeted hyperthermia. PMID:18257079

Kim, Dong-Hyun; Kim, Kyoung-Nam; Kim, Kwang-Mahn; Lee, Yong-Keun

2009-01-01

170

Biological cell positioning and spatially selective destruction via magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

We report a procedure on biological cells (erythrocytes) where magnetite (Fe3O4) nanoparticles have been used for micro-scale blood cell positioning and space selective destruction. The experiment was accomplished on the top of the microelectromagnet serving as a source of magnetic field and as a local heater at the same time. We observed the controlled motion and focusing of the blood cells dragged by the flow of magnetic nanoparticles. Furthermore, we found that the increase of the electric current through the microelectromagnet leads to the local cell haemolysis. The haemolysis is observed only in the vicinity (5-10 microns) of the current-carrying wires. The whole procedure takes less than 3 seconds. The obtained results provide a rich resource showing the dynamics of cell dragging by the magnetic nanoparticles and demonstrate the feasibility of using magnetic nanoparticles for cell positioning and surgery on the cellular level with micrometer-scale precision.

Gertz, Frederick; Azimov, Rustam; Khitun, Alexander

2012-07-01

171

Magnetic nanoparticles for multi-imaging and drug delivery.  

PubMed

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

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

2013-04-10

172

Synthesis and magnetic properties of iron-iron oxide nanoparticles  

Microsoft Academic Search

Monodisperse magnetic nanoparticles are of much interest for data storage and biomedical applications as well as for studies of the fundamental characteristics of magnetism on small length scales. In light of this attention, we have been investigating the properties of iron-iron oxide nanoparticles, prepared by modifying a recently developed solvent-based synthesis method that produces particles of well-defined size [1]. By

Anna Clausen; Yumi Ijiri

2004-01-01

173

FMR study of magnetic nanoparticles embedded in non-magnetic matrix  

Microsoft Academic Search

Purpose: The aim of this review is recapitulating the FMR study of low concentration of magnetic nanoparticles in non-magnetic matrices. Design\\/methodology\\/approach: Magnetic nanoparticles exhibit a variety of anomalous magnetic properties and they could be used for forming low concentration in different matrices. This way, they are being found to be allowing for effectively novel applications of FMR (ferromagnetic resonance) for

N. Guskos; E. A. Anagnostakis; A. Guskos

174

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

PubMed

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

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

2013-09-11

175

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.

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

2013-01-01

176

Polyoxometalate-stabilized, water dispersible Fe?Pt magnetic nanoparticles.  

PubMed

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. PMID:23412503

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

2013-03-21

177

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

PubMed Central

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

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

2013-01-01

178

Preparation of novel magnetic fluorescent nanoparticles using amino acids.  

PubMed

Nanotechnology has opened new gates to pharmaceutical sciences and medicine from the aspect of drug delivery and imaging systems. Currently, bimodal fluorescent-magnetic nanoparticles are of great interest to biomedical scientists. In order to constructing these kinds of nanoparticles, fluorescent molecules should be linked to a magnetic core, while luminescence quenching is prevented. In order to alleviate this effect, usually fluorescent molecules are attached to a magnetic core after a multistep hydrocarbon, polymer or silica coating, which significantly increases the particle's size and reduces its magnetic saturation value. In this study, for the first time, amino acids (L-lysine and L-arginine) have been used as a linker and spacer between a fluorescent molecule (FITC) and a magnetic nanoparticle (Fe(3)O(4)) in a simple, two-step synthesis. Also, 3-aminopropyltriethoxysilane (APTES) was used without any previous silica coating for fluorescent magnetic nanoparticles construction. Routinely APTES is used after silica coating by tetraethoxysilane (TEOS). Either of L-lysine, L-arginine and APTES coating provides surface functional groups which interact with the isothiocyanate group of FITC. According to the obtained results, amino acids could be used for successful construction of fluorescent magnetic nanoparticles in a simple synthesis pathway, without any significant impact on the excitation and emission properties of fluorescent molecule. PMID:23104022

Ebrahiminezhad, Alireza; Ghasemi, Younes; Rasoul-Amini, Sara; Barar, Jaleh; Davaran, Soodabeh

2012-09-05

179

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

180

Magnetic Properties of Bio-Synthesized Magnetite Nanoparticles  

SciTech Connect

Magnetic nanoparticles, which are unique because of both structural and functional elements, have various novel applications. The popularity and practicality of nanoparticle materials create a need for a synthesis method that produces quality particles in sizable quantities. This paper describes such a method, one that uses bacterial synthesis to create nanoparticles of magnetite. The thermophilic bacterial strain Thermoanaerobacter ethanolicus TOR-39 was incubated under anaerobic conditions at 65 C for two weeks in aqueous solution containing Fe ions from a magnetite precursor (akaganeite). Magnetite particles formed outside of bacterial cells. We verified particle size and morphology by using dynamic light scattering, X-ray diffraction, and transmission electron microscopy. Average crystallite size was 45 nm. We characterized the magnetic properties by using a superconducting quantum interference device magnetometer; a saturation magnetization of 77 emu/g was observed at 5 K. These results are comparable to those for chemically synthesized magnetite nanoparticles.

Rawn, Claudia J [ORNL; Yeary, Lucas W [ORNL; Moon, Ji Won [ORNL; Love, Lonnie J [ORNL; Thompson, James R [ORNL; Phelps, Tommy Joe [ORNL

2005-01-01

181

Magnetic birefringence of iron oxyhydroxide nanoparticles stabilised by sucrose  

NASA Astrophysics Data System (ADS)

Magnetically induced optical birefringence is used to investigate pharmaceutically important iron-sucrose aqueous suspensions. XRD and TEM measurements of the system of oxyhydroxide particles stabilised by sucrose have shown that this system contains iron oxyhydroxide in the form of 2-5 nm particles. The mineral form of the iron-core is suggested to be akaganeite. Anisotropy of the optical polarizability and magnetic susceptibility of akaganeite nanoparticles are calculated. The permanent dipole moment obtained for the nanoparticles studied was found to be negligible, in agreement with the characteristic superparamagnetic behaviour of the magnetic nanoparticles observed at room temperature. The Neel temperature of these nanoparticles is estimated as below 276 K. The results obtained are discussed against a background of the earlier studies of similar nanoscale systems.

Koralewski, M.; Pochylski, M.; Gierszewski, J.

2011-05-01

182

Size-dependent magnetic properties of calcium ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

The union of nanotechnology with the other fields of science heralds the influx of many newer and better technologies, with the capability to revolutionize the human life. In the present work, calcium ferrite nanoparticles were synthesized by conventional sol-gel method and were characterised by X-ray diffraction, Transmission electron microscope, Vibrating sample magnetometer and Fourier transform infrared spectroscope. The synthesized nanoparticles were calcined at different temperatures and their magnetic behaviour was studied. The synthesized nanoparticles calcined at 900 °C were formed in the shape of capsules and exhibited mixed characteristics of ferrimagnetic and paramagnetic grains with magnetic saturation of 0.85 emu/g whereas nanoparticles calcined at 500 °C were spherical in shape and exhibited superparamagnetic characteristics with saturation magnetization of 37.67 emu/g.

Khanna, Lavanya; Verma, N. K.

2013-06-01

183

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

184

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

NASA Astrophysics Data System (ADS)

Magnetic fluid based on cobalt ferrite nanoparticles was obtained using a hydrothermal treatment added to the Massart procedure. This treatment increases the average size of the nanoparticles from 11.9 to 18.7 nm and also improves the dispersity and crystallinity of the cobalt ferrite particles. The nanoparticles obtained after the hydrothermal treatment were dispersed in aqueous solvent by the classical procedure for ionic magnetic fluids. The ferrofluid thus obtained is stable at pH 7 and may be useful for hyperthermia applications.

Cabuil, Valérie; Dupuis, Vincent; Talbot, Delphine; Neveu, Sophie

2011-05-01

185

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

PubMed Central

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

2012-01-01

186

Regulation of PCR efficiency with magnetic nanoparticles in a rotating magnetic field  

NASA Astrophysics Data System (ADS)

The polymerase chain reaction (PCR) method is widely used for the reproduction and amplification of specific DNA segments in vitro, and a novel PCR method using nanomaterials such as gold nanoparticles has recently been reported. This paper reports on the regulation of PCR efficiency with superparamagnetic nanoparticles in a rotating magnetic field. The level of efficiency was successfully regulated in a rotating magnetic field by the authors, and decreased with increasing frequency of the field. The results obtained show that simply controlling the structure and dynamics of magnetic nanoparticle clusters in a rotating magnetic field can regulate PCR efficiency.

Higashi, Toshiaki; Nagaoka, Yutaka; Minegishi, Hiroaki; Echigo, Akinobu; Usami, Ron; Maekawa, Toru; Hanajiri, Tatsuro

2011-04-01

187

PREPARATION OF FLUORESCENT, FUNCTIONALIZED, SILICA-COATED MAGNETIC NANOPARTICLES MARKED WITH MONOCLONAL ANTIBODIES  

Microsoft Academic Search

Magnetic nanoparticles have been intensively studied for their potential applications in biomedicine. These magnetic nanoparticles are tested for in-vivo use, either in diagnosis as contrast agents for NMR imaging, or in therapy, for targeted drug delivery and for the treatment of cancer cells with magnetic hyperthermia. There are also many applications where these magnetic nanoparticles are used in-vitro, for example,

Slavko Kralj; Matija Rojnik; Janko Kos

2009-01-01

188

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

Microsoft Academic Search

Magnetic nanoparticles have recently attracted much attention for potential biomedical applications such as targeted drug delivery, magnetic resonance imaging contrast agents and hyperthermia treatment of cancerous cells. Future research on biomedical applications also includes use of magnetic nanoparticles for cell and DNA separation. By functionalizing magnetic nanoparticles with cells or DNA selective biomolecules, the particles attach to the target and

Srinivasan Balakrishnan

2010-01-01

189

Improved evaluation of magnetic nanoparticle susceptibility in hyperthermia, spectroscopy, and imaging  

Microsoft Academic Search

Magnetic nanoparticles are becoming increasingly important for both diagnosis (through applications such as MRI and magnetic particle imaging (MPI), which comes from the nonlinear magnetization of nanoparticles and provides images with both high spatial and temporal resolutions) as well as for therapy (through focal heating). Thus understanding and modeling of the magnetic susceptibility of the nanoparticles is critical. In hyperthermia

Yong Wu; Zhen Yao; Timothy Atherton; Lisa Bauer; Mark Griswold; Robert Brown

2011-01-01

190

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

191

Magnetic nanoparticles and concentrated magnetic nanofluids: Synthesis, properties and some applications  

Microsoft Academic Search

This paper reviews some recent results concerning chemical synthesis of magnetic nanoparticles and preparation of various types of magnetic nanofluids. Structural properties and behaviour in external magnetic field of magnetic nanofluids will be emphasized with relation to their use in leakage-free rotating seals and in biomedical applications.

Ladislau Vékás; Doina Bica; Mikhail V. Avdeev

2007-01-01

192

Tailored magnetic nanoparticles for optimizing magnetic fluid hyperthermia.  

PubMed

Magnetic Fluid Hyperthermia (MFH) is a promising approach towards adjuvant cancer therapy that is based on the localized heating of tumors using the relaxation losses of iron oxide magnetic nanoparticles (MNPs) in alternating magnetic fields (AMF). In this study, we demonstrate optimization of MFH by tailoring MNP size to an applied AMF frequency. Unlike conventional aqueous synthesis routes, we use organic synthesis routes that offer precise control over MNP size (diameter ?10 to 25 nm), size distribution, and phase purity. Furthermore, the particles are successfully transferred to the aqueous phase using a biocompatible amphiphilic polymer, and demonstrate long-term shelf life. A rigorous characterization protocol ensures that the water-stable MNPs meet all the critical requirements: (1) uniform shape and monodispersity, (2) phase purity, (3) stable magnetic properties approaching that of the bulk, (4) colloidal stability, (5) substantial shelf life, and (6) pose no significant in vitro toxicity. Using a dedicated hyperthermia system, we then identified that 16 nm monodisperse MNPs (?-0.175) respond optimally to our chosen AMF conditions (f = 373 kHz, H? = 14 kA/m); however, with a broader size distribution (?-0.284) the Specific Loss Power (SLP) decreases by 30%. Finally, we show that these tailored MNPs demonstrate maximum hyperthermia efficiency by reducing viability of Jurkat cells in vitro, suggesting our optimization translates truthfully to cell populations. In summary, we present a way to intrinsically optimize MFH by tailoring the MNPs to any applied AMF, a required precursor to optimize dose and time of treatment. PMID:22213652

Khandhar, Amit P; Ferguson, R Matthew; Simon, Julian A; Krishnan, Kannan M

2011-12-30

193

Synthesis and magnetic properties of iron oxide nanoparticles\\/C and ?-Fe\\/iron oxide nanoparticles\\/C composites  

Microsoft Academic Search

Magnetic iron oxide nanoparticles\\/C and ?-Fe\\/iron oxide nanoparticles\\/C composites were synthesized through the formation of polymer gel with highly dispersed magnetic iron oxide nanoparticles in hydrothermal system, followed by carbonizing the gel at 400 and 1000°C under N2 atmosphere, respectively. The phase component, structure and magnetic properties of these magnetic composites were characterized by X-ray diffraction analysis, transmission electron microscopy

Ying Xiong; Jing Ye; Xiaoyu Gu; Qianwang Chen

2008-01-01

194

Synthesis and magnetic properties of iron oxide nanoparticles\\/C and alpha-Fe\\/iron oxide nanoparticles\\/C composites  

Microsoft Academic Search

Magnetic iron oxide nanoparticles\\/C and alpha-Fe\\/iron oxide nanoparticles\\/C composites were synthesized through the formation of polymer gel with highly dispersed magnetic iron oxide nanoparticles in hydrothermal system, followed by carbonizing the gel at 400 and 1000 °C under N2 atmosphere, respectively. The phase component, structure and magnetic properties of these magnetic composites were characterized by X-ray diffraction analysis, transmission electron

Ying Xiong; Jing Ye; Xiaoyu Gu; Qianwang Chen

2008-01-01

195

Interface charge transfer in polypyrrole coated perovskite manganite magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

196

Biocompatible core-shell magnetic nanoparticles for cancer treatment  

NASA Astrophysics Data System (ADS)

Nontoxic magnetic nanoparticles (MNPs) have expanded treatment delivery options in the medical world. With a size range from 2 to 200 nm, MNPs can be compiled with most of the small cells and tissues in the living body. Monodispersive iron-iron oxide core-shell nanoparticles were prepared by our novel cluster deposition system. This unique method of preparing core-shell MNPs gives the nanoparticles a very high magnetic moment. We tested the nontoxicity and uptake of MNPs coated with/without dextrin by incubating them with rat LX-1 small cell lung cancer cells. Since core iron enhances the heating effect [L. Baker, Q. Zeing, W. Li, and S. Sullivan, J. Appl. Phys. 99, 08H106 (2006)], the rate of oxidation of iron nanoparticles was also tested in de-ionized water at a certain time interval. Both coated and noncoated MNPs were successfully uptaken by the cells, indicating that the nanoparticles were not toxic. The stability of MNPs was verified by x-ray diffraction scan after 0, 24, 48, 96, and 204 h. Due to the high magnetic moment offered by MNPs produced in our laboratory, we predict that even at low applied external alternating field, the desired temperature could be reached in cancer cells in comparison to the commercially available nanoparticles. Moreover our MNPs do not require additional transfection agent, providing a cost effective means of treatment with significantly lower dosage in the body in comparison to commercially available nanoparticles.

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

2008-04-01

197

Preparation of magnetic fluorescent hollow nanoparticles with multi-layer  

NASA Astrophysics Data System (ADS)

A kind of novel magnetic fluorescent hollow nanoparticles with multi-layer shells by layer-by-layer self-assembly process was presented in this paper. Non-crosslinking poly(acrylic acid) (PAA) nanoparticles as core with 250 nm in diameters were prepared by distillation-precipitation polymerization in acetonitrile with 2, 2'-Azobisisobutyronitrile (AIBN) as initiator and without any stabilizer and crosslinker. Then 4-vinylpyridine (4-VPy) as monomer was selfassembled on the surface of PAA nanoparticles because of hydrogen-bonding effect between the surface carboxyl of PAA nanoparticles and pyridine of 4-VPy. The 4-VPy as first shell layer were crosslinked by ethylene glycol dimethacrylate (EGDMA) by seeds distillation-precipitation polymerization in acetonitrile. The core/shell structure of this kind of nanoparticles was investigated by FT-IR and TEM. We can find that the products had an absorption peak at 1641 cm-1 from the FT-IR, which showed that the vinyl groups had been connected in the polyAA microspheres. After that, the non-crosslinking PAA core was removed under a solution of sodium hydroxide in ethanol-water. On the other hand, CdTe quantum dots (QDs) with about 3 nm in diameters as shell were prepared in aqueous solution with 3- mercaptopropionic acid (MPA) as stabilizer and 1, 6-hexylenediamime modified Fe3O4 nanoparticles with about 11 nm in diameters as core were synthesized in water respectively. Because of the hydrogen-bonding between the surface carboxyl of MPA on CdTe QDs and the amino on Fe3O4 nanoparticles, the core/shell magnetic-fluorescent nanoparticles were obtained. Then, the magnetic-fluorescent nanoparticles as second shell layer were self-assembled on the hollow 4VPy nanoparticles.

Sun, Xiuxue; Zhang, Jimei; Dai, Zhao; Li, Ping; Zhou, Wen; Zheng, Guo

2009-07-01

198

Synthesis and properties of magnetic ceramic nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic ceramic nanoparticles of the type xIn2O3-(1-x)alpha-Fe2O3, xV2O5-(1-x)alpha-Fe2O3 and xZnO-(1-x)alpha-Fe2O3 (x=0.1-0.7) were synthesized from the mixed oxides using mechanochemical activation for 0-12 hours. X-ray diffraction was used to derive the phase content, lattice constants and particle size information as function of ball milling time. Mossbauer spectroscopy results correlated with In3+, V5+ and Zn2+ substitution of Fe3+ in the hematite lattice. SEM/EDS measurements revealed that the mechanochemical activation by ball milling produced systems with a wide range of particle size distribution, from nanometer particles to micrometer agglomerates, but with a uniform distribution of the elements. Simultaneous DSC-TGA investigations up to 800 degrees C provided information on the heat flow, weight loss and the enthalpy of transformation in the systems under investigation. This study demonstrates the formation of a nanostructured solid solution for the indium oxide, an iron vanadate (FeVO4) for the vanadium oxide, and of the zinc ferrite (ZnFe2O4) for the zinc oxide. The transformation pathway for each case can be related to the oxidation state of the metallic specie of the oxide used in connection with hematite.

Sorescu, Monica

2012-02-01

199

The visualized polarity-sensitive magnetic nanoparticles.  

PubMed

Three polarity-sensitive organic molecules (DIAA, DIUA, and DISA) were designed and synthesized for functionalizing high-quality superparamagnetic Fe(3)O(4) nanoparticles (NPs) via the ligand exchange strategy to prepare polarity-sensitive Fe(3)O(4) NPs. The functional group is chosen to be the carboxyl group (one for DIAA and DIUA, two for DISA) that is a universal coordinating site for iron oxide NPs. The method for binding these functional molecules onto the surface of the NPs is simple and straightforward. Among the three molecules, the DISA molecules passivate the NPs' surface most efficiently owing to their particular structure with two carboxyl groups and a general good solubility. The DISA-functionalized Fe(3)O(4) NPs (DISA-Fe(3)O(4) NPs) display distinctly different fluorescence emissions in various solvents of different polarities with the magnetism well preserving. The prepared polarity-sensitive Fe(3)O(4) NPs that are dual functional can be used as a visualized polarity sensor and perform NPs' superparamagnetic properties simultaneously. It also provides a conceptual design for preparing the polarity-sensitive nanomaterials with multifunction. PMID:20143867

Zhang, Tian-Long; Han, Bao-Hang

2010-06-01

200

Size dependent magnetic properties of iron oxide nanoparticles  

Microsoft Academic Search

?Fe2O3 nanoparticles has been synthesized by a combination of chemical and ultrasonication procedure and further stabilized with surfactant. Their magnetic properties are compared with the different fractions (10–12, 20–30, 100–150nm) of commercially available iron oxide. The sizes obtained from the scanning transmission electron micrographs are correlated with the magnetic properties of the particles.

Jhunu Chatterjee; Yousef Haik; Ching-Jen Chen

2003-01-01

201

Temperature-induced phenomena in systems of magnetic nanoparticles  

Microsoft Academic Search

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

Abdul Wazed Bhuiya

2009-01-01

202

Novel hybrid materials of magnetic nanoparticles and cellulose fibers  

Microsoft Academic Search

In this study, magnetic cellulose fibers have been prepared by coating bleached Kraft fibers (Pinus radiata) with magnetite nanoparticles. In doing so, the inherent properties of the fiber (such as tensile strength and flexibility) have been preserved, but imparted to it are the magnetic properties of the coating. The surface coating approach used differs from other methods in the literature

Aaron C. Small; James H. Johnston

2009-01-01

203

Tomographic examination of magnetic nanoparticles used as drug carriers  

NASA Astrophysics Data System (ADS)

Tumors grown on animals and treated with magnetic drug targeting and magnetic hyperthermia have been analyzed by microcomputed X-ray tomography to study the three-dimensional nanoparticle distribution. The measurements have been performed in two laboratories, with a polychromatic X-ray cone beam as well as with monochromatic parallel beam. Due to the poor resolution in the first case, the distribution of the magnetic nanoparticles can be studied only qualitatively. With the polychromatic beam semi-quantitative results can be achieved. In this paper, the results from both methods are presented and compared.

Rahn, Helene; Gomez-Morilla, Inmaculada; Jurgons, Roland; Alexiou, Christoph; Eberbeck, Dietmar; Odenbach, Stefan

2009-05-01

204

Magnetic Nanoparticle Degradation in vivo Studied by Mössbauer Spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

205

Assembly and magnetic properties of nickel nanoparticles on silicon nanowires  

SciTech Connect

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

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

2009-01-01

206

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

207

Enhanced drug transport through alginate biofilms using magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

The development of microbiological biofilms greatly reduces the efficacy of antibiotic therapies and is a serious problem in chronic infection and for implantable medical devices. We investigated the potential of superparamagnetic nanoparticles to increase transport through in vitro models of alginate biofilms. An in vitro alginate biofilm model was developed to mimic the composition of in vivo samples of P. aeruginosa infections. Transport through this model biofilm was performed using both bulk diffusion methods and single particle tracking techniques in the presence and absence of an external magnetic field. Bulk diffusion of nanoparticles through the biofilm was significantly enhanced in the presence of a magnetic field, both visually and quantitatively. Nanoparticle trajectories also showed transport increases were significantly higher when magnetic fields were applied. We also showed that surface chemistry (cationic, anioni, or neutral) of the nanoparticles significantly influenced transport rates. Finally, nanoparticle size also influenced the transport rates and variability of transport rates through the biofilm. In these first studies using magnetic nanoparticles in bacterial biofilms, we demonstrate that transport enhancement can be achieved and further studies are warranted.

McGill, Shayna L.; Cuylear, Carla; Adolphi, Natalie L.; Osinski, Marek; Smyth, Hugh

2009-02-01

208

Palladium nanoparticle supported on cobalt ferrite: an efficient magnetically separable catalyst for ligand free Suzuki coupling  

Microsoft Academic Search

Synthesis of Pd nanoparticle supported on cobalt ferrite magnetic nanoparticles has been achieved by direct addition of Pd nanoparticles during synthesis of cobalt ferrite nanoparticles by ultrasound assisted co-precipitation in absence of any surface stabilizers or capping agent. The catalytic performance of the Pd incorporated cobalt ferrite nanoparticles was examined in Suzuki coupling reaction in ethanol under ligand free condition.

Kula Kamal Senapati; Subhasish Roy; Chandan Borgohain; Prodeep Phukan

209

Magnetic properties and microstructure of carbon encapsulated Ni nanoparticles and pure Ni nanoparticles coated with NiO layer  

Microsoft Academic Search

Two kinds of nickel nanoparticles—carbon encapsulated Ni nanoparticles Ni(C) and pure Ni nanoparticles coated with NiO layers Ni(O) are successfully prepared. Structural characterizations (HR-TEM, SAED, and XRD) reveal their distinct morphological properties. Magnetization measurements for the assemblies of two kinds of Ni nanoparticles show a larger coercivity and remanence by a deviation between the zero-field-cooled and the field-cooled magnetization below

Xiang-Cheng Sun; Xing-Long Dong

2002-01-01

210

Magnetic domains and surface effects in hollow maghemite nanoparticles  

SciTech Connect

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

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

2008-09-30

211

Magnetic properties of bacterial magnetosomes and chemosynthesized magnetite nanoparticles  

NASA Astrophysics Data System (ADS)

In this work, the magnetic properties of biologically produced magnetite (magnetosomes) by a mineralization process of magnetotactic bacteria {Magnetospirillum sp.} AMB-1 were compared to those of chemically synthesized magnetite nanoparticles and nanorods. X-ray diffraction data reveal that for all samples the peaks come from magnetite. A sharp magnetic transition (Verwey transition) is clearly observed in magnetosomes at 105 K (magnetite nanocrystals obtained by mineralization) and nanorodes at 112 K, in opposite, this transition is significantly smeared in Fe_{3}O_{4} powder, where the magnetic nanoparticles are separated and the magnetic fluctuations are strong to overcome magnetic anisotropy and randomize magnetic moment. The existence of coercivity of 71 Oe at room temperature is related to the fact that the mean diameter (34 nm) is larger than the critical size for the transition from superparamagnetic to ferromagnetic behaviour. Figs 6, Refs 14.

Timko, M.; Dzarova, A.; Zavisova, V.; Koneracka, M.; Sprincova, A.; Kopcansky, P.; Kovac, J.; Vavra, I.; Szlaferek, A.

2008-06-01

212

Cell uptake enhancement of folate targeted polymer coated magnetic nanoparticles.  

PubMed

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

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

2013-06-01

213

Synthesis of pure iron magnetic nanoparticles in large quantity  

NASA Astrophysics Data System (ADS)

Free nanoparticles of iron (Fe) and their colloids with high saturation magnetization are in demand for medical and microfluidic applications. However, the oxide layer that forms during processing has made such synthesis a formidable challenge. Lowering the synthesis temperature decreases rate of oxidation and hence provides a new way of producing pure metallic nanoparticles prone to oxidation in bulk amount (large quantity). In this paper we have proposed a methodology that is designed with the knowledge of thermodynamic imperatives of oxidation to obtain almost oxygen-free iron nanoparticles, with or without any organic capping by controlled milling at low temperatures in a specially designed high-energy ball mill with the possibility of bulk production. The particles can be ultrasonicated to produce colloids and can be bio-capped to produce transparent solution. The magnetic properties of these nanoparticles confirm their superiority for possible biomedical and other applications.

Tiwary, C. S.; Kashyap, S.; Biswas, K.; Chattopadhyay, K.

2013-09-01

214

Targeting of Breast Tumors and Tumor Cells Using Inductive Magnetic Heating of Metallic Nanoparticles.  

National Technical Information Service (NTIS)

Our research in the first year has focused on the creation of nanoparticles designed for hyperthermic tumor ablation via magnetic field heating, and the development of equipment for genetic magnetic field generation. In the area of nanoparticle fabricatio...

V. M. Rotello

2004-01-01

215

Processing, properties and some novel applications of magnetic nanoparticles  

Microsoft Academic Search

Magnetic nanoparticles have been prepared by various soft chemical methods including self-assembly. The bare or surface-modified\\u000a particles find applications in areas such as hyperthermia treatment of cancer and magnetic field-assisted radioactive chemical\\u000a separation. We present here some of the salient features of processing of nanostructured magnetic materials of different sizes\\u000a and shapes, their properties and some possible applications. The materials

D. Bahadur; J. Giri; Bibhuti B. Nayak; T. Sriharsha; P. Pradhan; N. K. Prasad; K. C. Barick; R. D. Ambashta

2005-01-01

216

Synthesis of Ibuprofen Loaded Magnetic Solid Lipid Nanoparticles  

Microsoft Academic Search

Ibuprofen loaded magnetic solid lipid nanoparticles (Ib-MSLNs) were successfully fabricated using a two-step method: 1)preparation of a warm O\\/W microemulsion (aqueous surfactant solution with a lipid phase, containing Ibuprofen, stearic acid, 1-octadecanol and lecithin) in which modified lipophilic magnetite (Fe3O4) nanoparticles were incorporated, and 2)formation of MSLNs by dispersing the warm microemulsion in cold water under mechanical stirring. The Ib-MSLNs

X. J. Pang; J. Zhou; J. J. Chen; M. H. Yu; F. D. Cui; W. L. Zhou

2007-01-01

217

Crystallization process and magnetic properties of amorphous iron oxide nanoparticles  

Microsoft Academic Search

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 gamma-Fe2O3 (with an activation energy of 0.71 eV) and the hematite alpha-Fe2O3 (with an

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

2011-01-01

218

Smart composites based on magnetic nanoparticles and responsive polymers  

Microsoft Academic Search

A comparative study of the properties of smart composites obtained by the combination of Fe3O4 nanoparticles with biocompatible responsive polymers is reported. Two types of magnetic composites with different morphology were obtained: (i) as core-shell nanostructures consisting of Fe3O4 functionalized by serine and covered with biocompatible polymer shell poly(caprolactone); (ii) as smart ferrogels, by the encapsulation of Fe3O4 nanoparticles into

R. Turcu; A. Nan; I. Craciunescu; O. Pana; C. Leostean; S. Macavei

2009-01-01

219

Magnetic nanoparticles produced by surfactant-assisted ball milling  

Microsoft Academic Search

However, the size distribution of the particles obtained by ball milling can be quite wide compared with the chemical methods. The chemical methods, nevertheless, have had lim- ited success in the synthesis of hard magnetic nanoparticles of rare-earth compounds.7,8 Traditionally, surfactant-assisted ball milling technique has been used mainly for preparing ferrite nanoparticles, and not many studies have been con- ducted

V. M. Chakka; B. Altuncevahir; Z. Q. Jin; Y. Li; J. P. Liua

220

Synthesis and characterization of nickel ferrite magnetic nanoparticles  

Microsoft Academic Search

Nickel ferrite (NiFe2O4) nanoparticles are prepared by a polyvinyl alcohol (PVA) assisted sol–gel auto-combustion method. The structure, composition, morphology and magnetic properties of the gel precursor are characterized by powder XRD, FT-IR, TGA, HR-SEM, TEM, HR-TEM and VSM. XRD confirms the formation of single-phase nickel ferrite with space group of Fd3m and inverse spinel structure. The vibration properties of nanoparticles

P. Sivakumar; R. Ramesh; A. Ramanand; S. Ponnusamy; C. Muthamizhchelvan

2011-01-01

221

Design and synthesis of plasmonic magnetic nanoparticles  

Microsoft Academic Search

Core shell nanoparticles containing both iron oxide and gold are proposed for bioseparation applications. The surface plasmon resonance of gold makes it possible to track the positions of individual particles, even when they are smaller than the optical diffraction limit. The synthesis of water-dispersible iron oxide-gold nanoparticles is described. Absorption spectra show the plasmon peaks for Au shells on silica

Jitkang Lim; Robert D. Tilton; Alexander Eggeman; Sara A. Majetich

2007-01-01

222

High efficiency protein separation with organosilane assembled silica coated magnetic nanoparticles  

Microsoft Academic Search

This work describes the development of high efficiency protein separation with functionalized organosilanes on the surface of silica coated magnetic nanoparticles. The magnetic nanoparticles were synthesized with average particle size of 9 nm and silica coated magnetic nanoparticles were obtained by controlling the coating thicknesses on magnetic nanoparticles. The silica coating thickness could be uniformly sized with a diameter of 10–40 nm

Jeong Ho Chang; Ki Ho Kang; Jinsub Choi; Young Keun Jeong

2008-01-01

223

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

Microsoft Academic Search

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. gamma- 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

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

2009-01-01

224

Magnetocaloric effect in magnetic nanoparticle systems: how to choose the best magnetic material?  

PubMed

Magnetic nanoparticles with controlled magnetocaloric properties are a good candidate to lower the temperature of nanosized systems: they are easy to manipulate and to distribute into different geometries, as wires or planes. Using a Monte Carlo technique we study the entropy change and refrigerant capacity of an assembly of fine magnetic particles as a function of their anisotropy and magnetization, key-parameters of the magnetic behavior of the system. We focus our attention on the anisotropy energy/dipolar energy ratio by means of the related parameter c0 = 2K/M(S)2, where K is the anisotropy constant and M(S) is the saturation magnetization of the nanoparticles. Making to vary the value of co parameter by choosing different K-M(S) combinations, allows us to discuss how the magnetocaloric response of an assembly of magnetic nanoparticles may be tuned by an appropriate choice of the magnetic material composition. PMID:20355455

Serantes, D; Baldomir, D; Pereiro, M; Botana, J; Prida, V M; Hernando, B; Arias, J E; Rivas, J

2010-04-01

225

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

NASA Astrophysics Data System (ADS)

The magnetic properties of densely packed magnetic nanoparticles (MNP) assemblies are investigated from Monte Carlo simulations. The case of iron oxide nanoparticles is considered as a typical example of MNP. The main focus is put on particle size, and size polydispersity influences on the magnetization curve. The particles are modeled as uniformly magnetized spheres isolated one from each other by a non magnetic layer representing the organic coating. A comparison with recent experimental results on ?-Fe2O3 powder samples differing by their size is given.

Russier, Vincent; de Montferrand, Caroline; Lalatonne, Yoann; Motte, Laurence

2012-10-01

226

TOPICAL REVIEW: Applications of magnetic nanoparticles in biomedicine  

NASA Astrophysics Data System (ADS)

The physical principles underlying some current biomedical applications of magnetic nanoparticles are reviewed. Starting from well-known basic concepts, and drawing on examples from biology and biomedicine, the relevant physics of magnetic materials and their responses to applied magnetic fields are surveyed. The way these properties are controlled and used is illustrated with reference to (i) magnetic separation of labelled cells and other biological entities; (ii) therapeutic drug, gene and radionuclide delivery; (iii) radio frequency methods for the catabolism of tumours via hyperthermia; and (iv) contrast enhancement agents for magnetic resonance imaging applications. Future prospects are also discussed.

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

2003-07-01

227

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

Microsoft Academic Search

In the presence of alternating-sinusoidal or rotating magnetic fields, magnetic nanoparticles will act to realign their magnetic moment with the applied magnetic field. The realignment is characterized by the nanoparticle's time constant, ?. As the magnetic field frequency is increased, the nanoparticle's magnetic moment lags the applied magnetic field at a constant angle for a given frequency, ?, in rads?1.

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

2010-01-01

228

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

229

Static and dynamic magnetic properties of Co nanoparticles.  

PubMed

Co nanoparticles have been synthesized using wet-chemical methods. As-synthesized particles show a sharp low temperature peak in zero-field cooled (ZFC) magnetization well below the blocking transition temperature and this feature is associated with surface spin disorder. We have investigated the dynamic magnetic properties of Co using ac susceptibility and resonant RF transverse susceptibility (TS). We also studied the memory and relaxation effects in these nanoparticle systems. From these measurements we show a typical blocking behavior of an assembly of superparamagnetic nanoparticles with a wide distribution of blocking temperatures. The transverse susceptibility measurements on these particles show the presence of anisotropy even above the blocking temperature. The role of surface anisotropy and the size distribution of the particles on the observed memory and magnetic relaxation effects are discussed. PMID:19049180

Srinath, S; Poddar, P; Sidhaye, Deepti S; Prasad, B L V; Gass, J; Srikanth, H

2008-08-01

230

Magnetic conjugated polymer nanoparticles as bimodal imaging agents.  

PubMed

Hybrid nanoparticles which incorporate multiple functionalities, such as fluorescence and magnetism, can exhibit enhanced efficiency and versatility by performing several tasks in parallel. In this study, magnetic-fluorescent semiconductor polymer nanospheres (MF-SPNs) have been synthesized by encapsulation of hydrophobic conjugated polymers and iron oxide nanoparticles in phospholipid micelles. Four fluorescent conjugated polymers were used, yielding aqueous dispersions of nanoparticles which emit across the visible spectrum. The MF-SPNs were shown to be magnetically responsive and simultaneously fluorescent. In MRI studies, they were seen to have a shortening effect on the transverse T(2)* relaxation time, which demonstrates their potential as an MR contrast agent. Finally, successful uptake of the MF-SPNs by SH-SY5Y neuroblastoma cells was demonstrated, and they were seen to behave as bright and stable fluorescent markers. There was no evidence of toxicity or adverse affect on cell growth. PMID:20572665

Howes, Philip; Green, Mark; Bowers, Alex; Parker, David; Varma, Gopal; Kallumadil, Mathew; Hughes, Mary; Warley, Alice; Brain, Anthony; Botnar, Rene

2010-07-21

231

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

232

Photoinduced Magnetism in Nanoparticles of Prussian Blue Derivatives  

NASA Astrophysics Data System (ADS)

Nanoparticles of the Prussian blue family are of great interest due to the possibility for applications in magnetic memory, biosensing, and magnetic filtering. Nanoparticles also serve to better investigate fascinating phenomena, such as the anisotropic photomagnetic properties seen in thin films of Prussian blue derivatives. Here, we present results on RbjCok[Fe(CN)6]l.nH2O Prussian blue analog nanoparticles, which exhibit photoinduced magnetism. The nanoparticles are synthesized in a controlled manner, which allows for particle growth in the range of 5-50 nm. Early experiments show that upon irradiation with light at 5 K for a period of 2 hours, the final magnetization increases on the order of 10-100% compared to the initial dark state value. This increase is comparable in magnitude with the results reported for bulk materials. The change in magnetization is also accompanied by an increase in Tc. Furthermore, the effect of the dispersing agent on the photomagnetism, the size effect on characteristic magnetic properties, and ac susceptibility data will be presented. J.-H. Park, E. Cizm'ar, M. W. Meisel, Y. D. Huh, F. Frye, S. Lane, and D. R. Talham, Appl. Phys. Lett. 85, 3797 (2004).

Anderson, N. E.; Park, J.-H.; Meisel, M. W.; Frye, F.; Talham, D. R.

2006-03-01

233

Cytokine adsorption\\/release on uniform magnetic nanoparticles for localized drug delivery  

Microsoft Academic Search

Attachment of cytokines to magnetic nanoparticles has been developed as a system for controlled local drug release in cancer therapy. We studied the adsorption\\/release of murine interferon gamma (IFN-?) on negatively charged magnetic nanoparticles prepared by three different methods, including coprecipitation, decomposition in organic media, and laser pyrolysis. To facilitate IFN-? adsorption, magnetic nanoparticles were surface modified by distinct molecules

Raquel Mejías; Rocío Costo; Alejandro G. Roca; Cristina F. Arias; Sabino Veintemillas-Verdaguer; Teresita González-Carreño; María del Puerto Morales; Carlos J. Serna; Santos Mañes; Domingo F. Barber

2008-01-01

234

Monitoring colloidal stability of polymer-coated magnetic nanoparticles using AC susceptibility measurements  

Microsoft Academic Search

The application of the response of magnetic nanoparticles to oscillating magnetic fields to probe transitions in colloidal state and structure of polymer-coated nanoparticles is demonstrated. Cobalt ferrite nanoparticles with narrow size distribution were prepared and shown to respond to oscillating magnetic fields through a Brownian relaxation mechanism, which is dependent on the mechanical coupling between the particle dipoles and the

Adriana P. Herrera; Carola Barrera; Yashira Zayas; Carlos Rinaldi

2010-01-01

235

A Two-Magnet System to Push Therapeutic Nanoparticles  

PubMed Central

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

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

2010-01-01

236

A Two-Magnet System to Push Therapeutic Nanoparticles.  

PubMed

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

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

2010-12-01

237

Intracellular Confinement of Magnetic Nanoparticles by Living Cells: Impact for Imaging and Therapeutic Applications  

NASA Astrophysics Data System (ADS)

Superparamagnetic properties of iron-oxide nanoparticles paved the way for various biomedical applications, such as magnetic resonance imaging (MRI), magnetic targeting of drug vectors or magnetically-induced therapeutic hyperthermia. Living cells interact with nanoparticles by internalizing them within intracellular compartments, called lysosomes. In the course of cellular uptake, the spatial distribution of magnetic nanoparticles changes from dilute isolated nanoparticles to a highly concentrated assembly of nanoparticles confined in micrometric lysosomes. This local organization of nanoparticles, which is induced by the intracellular environment, may have important consequences for their superparamagnetic behaviour. In particular, it may deeply affect their magnetic properties used for biomedical purposes and therefore must be considered when optimizing the properties of nanoparticles for a peculiar application. In this paper, we review the role of intracellular confinement of nanoparticles for their three main biomedical uses: MR cellular imaging, magnetic targeting of cells and magnetically induced hyperthermia.

Gazeau, Florence; Lévy, Michael; Wilhelm, Claire

2011-03-01

238

Magnetic entropy change in core/shell and hollow nanoparticles  

NASA Astrophysics Data System (ADS)

The development of positive magnetic entropy change in the case of ferromagnetic (FM) nanostructures is a rare occurrence. We observe positive magnetic entropy change in core/shell (Fe/?-Fe2O3) and hollow (?-Fe2O3) nanoparticles and its origin is attributed to a disordered state in the nanoparticles due to the random distribution of anisotropy axes which inhibits any long range FM ordering. The effect of the energy barrier distribution on the magnetic entropy change and its impact on the universal behavior based on rescaled entropy change curves for core/shell and hollow nanostructures is discussed. Our study emphasizes that the magnetic entropy change is an excellent parameter to study temperature and field dependent magnetic freezing in such complex nanostructures.

Chandra, Sayan; Biswas, Anis; Khurshid, Hafsa; Li, Wanfeng; Hadjipanayis, G. C.; Srikanth, Hariharan

2013-10-01

239

Magnetic entropy change in core/shell and hollow nanoparticles.  

PubMed

The development of positive magnetic entropy change in the case of ferromagnetic (FM) nanostructures is a rare occurrence. We observe positive magnetic entropy change in core/shell (Fe/?-Fe2O3) and hollow (?-Fe2O3) nanoparticles and its origin is attributed to a disordered state in the nanoparticles due to the random distribution of anisotropy axes which inhibits any long range FM ordering. The effect of the energy barrier distribution on the magnetic entropy change and its impact on the universal behavior based on rescaled entropy change curves for core/shell and hollow nanostructures is discussed. Our study emphasizes that the magnetic entropy change is an excellent parameter to study temperature and field dependent magnetic freezing in such complex nanostructures. PMID:24077419

Chandra, Sayan; Biswas, Anis; Khurshid, Hafsa; Li, Wanfeng; Hadjipanayis, G C; Srikanth, Hariharan

2013-09-27

240

Analytical methods for separating and isolating magnetic nanoparticles.  

PubMed

Despite the large body of literature describing the synthesis of magnetic nanoparticles, few analytical tools are commonly used for their purification and analysis. Due to their unique physical and chemical properties, magnetic nanoparticles are appealing candidates for biomedical applications and analytical separations. Yet in the absence of methods for assessing and assuring their purity, the ultimate use of magnetic particles and heterostructures is likely to be limited. In this review, we summarize the separation techniques that have been initially used for this purpose. For magnetic nanoparticles, it is the use of an applied magnetic flux or field gradient that enables separations. Flow based techniques are combined with applied magnetic fields to give methods such as magnetic field flow fractionation and high gradient magnetic separation. Additional techniques have been explored for manipulating particles in microfluidic channels and in mesoporous membranes. Further development of these and new analytical tools for separation and analysis of colloidal particles is critically important to enable the practical use of these, particularly for medicinal purposes. PMID:22306911

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

2012-02-03

241

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.

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

2009-01-01

242

Properties of magnetic nanoparticles in the Brownian relaxation range for liquid phase immunoassays  

Microsoft Academic Search

Properties of magnetic nanoparticles in the Brownian relaxation region were studied. Using the magnetic nanoparticles that exhibit remanence, we measured the magnetic properties, such as static magnetization, magnetic relaxation, and alternating current susceptibility, in a solution. Comprehensive comparisons were made between the experimental results and the theoretical ones predicted from the Brownian relaxation. From the comparison, the distributions of the

K. Enpuku; T. Tanaka; T. Matsuda; F. Dang; N. Enomoto; J. Hojo; K. Yoshinaga; F. Ludwig; F. Ghaffari; E. Heim; M. Schilling

2007-01-01

243

Heat dissipation mechanism of magnetite nanoparticles in magnetic fluid hyperthermia  

NASA Astrophysics Data System (ADS)

The relative contributions of Néel and Brownian relaxations on magnetic heat dissipation were studied by investigating the physical, magnetic and heating characteristics of magnetite nanoparticle suspensions with average diameters of 12.5 and 15.7 nm. Heating characteristics depended on the dispersion states of particles. The specific absorption rates (SAR) dropped by 27% for the 12.5 nm particles to 16.8×10-9 W g-1 Oe-2 Hz-1 and by 67% for the 15.7 nm particles to 9.69×10-9 W g-1 Oe-2 Hz-1, when the particle rotation was suppressed by dispersing magnetite nanoparticles in hydro-gel.

Suto, Makoto; Hirota, Yasutake; Mamiya, Hiroaki; Fujita, Asaya; Kasuya, Ryo; Tohji, Kazuyuki; Jeyadevan, Balachandran

2009-05-01

244

Multifunctional magnetic nanoparticles for targeted imaging and therapy  

PubMed Central

Magnetic nanoparticles have become important tools for the imaging of prevalent diseases, such as cancer, atherosclerosis, diabetes, and others. While first generation nanoparticles were fairly nonspecific, newer generations have been targeted to specific cell types and molecular targets via affinity ligands. Commonly, these ligands emerge from phage or small molecule screens, or are based on antibodies or aptamers. Secondary reporters and combined therapeutic molecules have further opened potential clinical applications of these materials. This review summarizes some of the recent biomedical applications of these newer magnetic nanomaterials.

McCarthy, Jason R.; Weissleder, Ralph

2008-01-01

245

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.

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

2010-01-01

246

Design and synthesis of plasmonic magnetic nanoparticles  

Microsoft Academic Search

Core–shell nanoparticles containing both iron oxide and gold are proposed for bioseparation applications. The surface plasmon resonance of gold makes it possible to track the positions of individual particles, even when they are smaller than the optical diffraction limit. The synthesis of water-dispersible iron oxide-gold nanoparticles is described. Absorption spectra show the plasmon peaks for Au shells on silica particles,

JitKang Lim; Robert D. Tilton; Alexander Eggeman; Sara A. Majetich

2007-01-01

247

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

Microsoft Academic Search

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

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

2006-01-01

248

Magnetic field synthesis of Fe 3O 4 nanoparticles used as a precursor of ferrofluids  

Microsoft Academic Search

Methods to synthesize magnetic Fe3O4 nanoparticles and to modify the nanoparticle surface are presented in this paper. In these methods, Fe3O4 nanoparticles were prepared by co-precipitation, and the aging of nanoparticles was improved by applied magnetic field. The obtained nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and vibrating sample magnetometer

R. Y. Hong; T. T. Pan; Y. P. Han; H. Z. Li; J. Ding; Sijin Han

2007-01-01

249

Magnetic Nanoparticles in-vivo Detection of Transplant Rejection  

NASA Astrophysics Data System (ADS)

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

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

2006-03-01

250

Magnetic Core-Shell Morphology of Structurally Uniform Magnetite Nanoparticles  

NASA Astrophysics Data System (ADS)

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

Krycka, Kathryn

2011-03-01

251

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

252

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

253

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

PubMed

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

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

2011-09-16

254

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

PubMed

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

255

Numerical study of magnetic nanoparticles concentration in biofluid (blood) under influence of high gradient magnetic field  

NASA Astrophysics Data System (ADS)

Ferrofluids are widely used in pharmaceutical industries as magnetic separation tools, anti-cancer drug carriers and micro-valve applications. The purpose of the current study is to investigate the effect of a magnetic field on the volume concentration of magnetic nanoparticles of a non-Newtonian biofluid (blood) as a drug carrier. The effect of particles on the flow field is considered. The governing non-linear differential equations, concentration and Naviar-stokes are coupled with the magnetic field. To solve these equations, a finite volume based code is developed and utilized. The results show accumulation of magnetic nanoparticles near the magnetic source until it looks like a solid object. The accumulation of nanoparticles is due to the magnetic force that overcomes the fluid drag force. As the magnetic strength and size of the magnetic particles increase, the accumulation of nanoparticles increases, as well. The magnetic susceptibility of particles also affects the flow field and the contour of the concentration considerably.

Reza Habibi, Mohammad; Ghasemi, Majid

2011-01-01

256

Magnetic nanoparticle targeted hyperthermia of cutaneous Staphylococcus aureus infection.  

PubMed

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 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; Lin, Hubert; Nayfach, Joseph; Simon, Scott I

2012-11-13

257

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

PubMed

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

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

2011-01-21

258

Properties of Magnetic Nanoparticles for Magnetic Immunoassays Utilizing a Superconducting Quantum Interference Device  

NASA Astrophysics Data System (ADS)

Properties of magnetic nanoparticles are studied for application to magnetic immunoassays utilizing a superconducting quantum interference device (SQUID). In this application, a magnetic marker is made of magnetic nanoparticles, and the binding reaction between an antigen and its antibody is detected by measuring the magnetic field from the marker. Magnetization of an assembly of the particles is simulated when the effects of the thermal noise and the distribution of the particle size are taken into account. Magnetic signals from the assembly of the particles are clarified for three detection methods, i.e., susceptibility, relaxation and remanence. From the comparison with experimental results, it was shown that the demagnetization effect also significantly influences the magnetic signal from the particles. When these effects are taken into account, the simulation results agree semi-quantitatively with the experimental ones.

Enpuku, Keiji; Inoue, Katsuhiro; Soejima, Kazuyuki

2005-01-01

259

Encapsulated magnetic nanoparticles as supports for proteins and recyclable biocatalysts.  

PubMed

This paper describes the bioconjugation of histidine-tagged enzymes and other proteins to the surface of composite "magnetomicelles" consisting of magnetic gamma-Fe2O3 nanoparticles encapsulated within cross-linked polystyrene-block-polyacrylate copolymer micelle shells. Free carboxylic acid groups on the magnetomicelle surface were converted to Cu2+-iminodiacetic acid (IDA) for protein capture. The conjugation of T4 DNA ligase and enhanced green fluorescent protein to magnetomicelles revealed that proteins were captured with a high surface density and could be magnetically separated from reaction mixtures and subsequently released from the nanoparticle surface. Additionally, bioconjugation of T7 RNA polymerase yielded a functional enzyme that maintained its biological activity and could be recycled for up to three subsequent transcription reactions. We propose that protein-magnetomicelle bioconjugates are effective for protein bioseparation and enzymatic recycling and further strengthen the idea that nanoparticle surfaces have utility in protein immobilization. PMID:17226972

Herdt, Aimee R; Kim, Byeong-Su; Taton, T Andrew

260

Human erythrocytes as nanoparticle carriers for magnetic particle imaging  

NASA Astrophysics Data System (ADS)

The potential of red blood cells (RBCs) loaded with iron oxide nanoparticles as a tracer material for magnetic particle imaging (MPI) has been investigated. MPI is an emerging, quantitative medical imaging modality which holds promise in terms of sensitivity in combination with spatial and temporal resolution. Steady-state and dynamic magnetization measurements, supported by semi-empirical modeling, were employed to analyze the MPI signal generation using RBCs as novel biomimetic constructs. Since the superparamagnetic iron oxide (SPIO) bulk material that is used in this study contains nanoparticles with different sizes, it is suggested that during the RBC loading procedure, a preferential entrapment of nanoparticles with hydrodynamic diameter <=60 nm occurs by size-selection through the erythrocyte membrane pores. This affects the MPI signal of an erythrocyte-based tracer, compared to bulk. The reduced signal is counterbalanced by a higher in vivo stability of the SPIO-loaded RBCs constructs for MPI applications.

Markov, D. E.; Boeve, H.; Gleich, B.; Borgert, J.; Antonelli, A.; Sfara, C.; Magnani, M.

2010-11-01

261

Magnetic Iron Oxide Nanoparticles: Synthesis and Surface Functionalization Strategies  

Microsoft Academic Search

Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely\\u000a used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation,\\u000a structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application\\u000a briefly. In order to implement the practical application,

Wei Wu; Quanguo He; Changzhong Jiang

2008-01-01

262

Tomographic examination of magnetic nanoparticles used as drug carriers  

Microsoft Academic Search

Tumors grown on animals and treated with magnetic drug targeting and magnetic hyperthermia have been analyzed by microcomputed X-ray tomography to study the three-dimensional nanoparticle distribution. The measurements have been performed in two laboratories, with a polychromatic X-ray cone beam as well as with monochromatic parallel beam. Due to the poor resolution in the first case, the distribution of the

Helene Rahn; Inmaculada Gomez-Morilla; Roland Jurgons; Christoph Alexiou; Dietmar Eberbeck; Stefan Odenbach

2009-01-01

263

Characterization of magnetic nanoparticles by a modular Hall magnetometer  

Microsoft Academic Search

The magnetization of iron oxide, nickel and cobalt ferrite nanoparticles was successfully measured by using a modular magnetometer. The magnetometer was built by combining stand-alone equipments usually available at most laboratories such as a Gaussmeter, an electromagnet, a current source and a linear actuator. The magnetic moment sensitivity attained was about 10-6 Am2 and the results were checked against measurements

J. F. D. F. Araújo; A. C. Bruno; H. R. Carvalho

2010-01-01

264

Exchange bias properties and surface spin freezing in magnetic nanoparticles  

Microsoft Academic Search

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

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

2010-01-01

265

Characterization of magnetic nanoparticles by a modular Hall magnetometer  

Microsoft Academic Search

The magnetization of iron oxide, nickel and cobalt ferrite nanoparticles was successfully measured by using a modular magnetometer. The magnetometer was built by combining stand-alone equipments usually available at most laboratories such as a Gaussmeter, an electromagnet, a current source and a linear actuator. The magnetic moment sensitivity attained was about 10?6Am2 and the results were checked against measurements made

J. F. D. F. Araújo; A. C. Bruno; H. R. Carvalho

2010-01-01

266

Embedding magnetic nanoparticles into polysaccharide-based hydrogels for magnetically assisted bioseparation.  

PubMed

Based on the preparation of biocompatible polysaccharide-based hydrogels with stimuli-responsive properties by the copolymerization of maleilated carboxymethyl chitosan with N-isopropylacrylamide, novel magnetic hybrid hydrogels were fabricated by the in situ embedding of magnetic iron oxide nanoparticles into the porous hydrogel networks. Scanning electron microscopy (SEM) and thermogravimetric (TG) analyses showed that the size, morphology, and content of the iron oxide nanoparticles formed could be modulated by controlling the amount of maleilated carboxymethyl chitosan. As confirmed by X-ray diffractometry (XRD), equilibrium swelling ratio, and differential scanning calorimetry (DSC) measurements, the embedding process did not induce a phase change of the magnetic iron oxide nanoparticles, and the resultant hybrid hydrogels could retain the pH- and temperature-responsive characteristics of their hydrogel precursors. By investigating the partition coefficients of bovine serum albumin as a model protein, this magnetic hydrogel material was found to hold a potential application in magnetically assisted bioseparation. PMID:17926314

Liang, Yuan-Yuan; Zhang, Li-Ming; Jiang, Wei; Li, Wei

2007-11-12

267

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

PubMed

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

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

2013-09-12

268

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.

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

2013-01-01

269

Magnetic nanoparticle effects on the red blood cells  

Microsoft Academic Search

In vitro tests on magnetite colloidal nanoparticles effects upon animal red blood cells were carried out. Magnetite cores were stabilized with citric acid in the form of biocompatible magnetic fluid administrated in different dilutions in the whole blood samples. The hemolysis extent was found increased up to 2.75 in horse blood and respectively up to 2.81 in the dog blood.

D. E. Creanga; M. Culea; C. Nadejde; S. Oancea; L. Curecheriu; M. Racuciu

2009-01-01

270

Hydrophobic partitioning approach to efficient protein separation with magnetic nanoparticles  

Microsoft Academic Search

A novel approach to the hydrophobic partitioning effect on efficient separation of protein such as BSA was demonstrated by the modification of hydrophobic pockets on the surface of silica-coated magnetic nanoparticles with various alkyl groups at various pH levels. The separation efficiency is strongly reflected and can be attained by controlling the size of the hydrophobic pocket and other factors

Jeong Ho Chang; Jiho Lee; Yeonhwan Jeong; Jin Hyung Lee; Ik Jin Kim; Sang Eon Park

2010-01-01

271

Synthesizing Distributions of Magnetic Nanoparticles for Clinical Hyperthermia  

Microsoft Academic Search

An automated procedure based on evolutionary computation and Finite Element Analysis (FEA) is proposed to synthesize the optimal distribution of nanoparticles (NPs) in multi-site injection for a Magnetic Fluid Hyperthermia (MFH) therapy. In particular a bi-objective formulation of the synthesis problem is considered taking into account both surface and volume temperature distribution in the tumor region.

Paolo Di Barba; Fabrizio Dughiero; Elisabetta Sieni

2012-01-01

272

Surface magnetism in amine-capped ZnO nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic behaviors of pure ZnO nanoparticles have been investigated both experimentally and theoretically. It is found that monodisperse ZnO nanoparticles wrapped with oleylamine with an average particle size of about 9.6 nm prepared by thermal decomposition do show ferromagnetic behavior with a saturation magnetization of about 34 memu g-1 and coercive force of about 22 Oe, whereas ZnO nanoparticles with an average particle size of 5.2 nm prepared by ultrasonic irradiation without solvents show a weak ferromagnetic property with a saturation magnetization of about 0.12 memu g-1 and coercive force of about 150 Oe at ambient temperature. First-principles calculations reveal that the 2p holes on the atoms at the surface (dangling bond of O atoms at ZnO(000\\bar {1} ) or 2p electrons of N atom in NH3 adsorbed on Zn(0001)) could be the source for the magnetic behavior of oxide nanoparticles.

Liu, J. F.; Liu, En-Zuo; Wang, H.; Su, N. H.; Qi, J.; Jiang, J. Z.

2009-04-01

273

Optical and magnetic manipulation of hybrid micro and nanoparticle sensors  

Microsoft Academic Search

Microparticles and nanoparticles have been used in a wide variety of applications ranging from biomedical to optical and electronic technologies. The microscopic and mesoscopic size scale of single particles makes them ideal tools for probing the local environments of biological cells, sensing the viscous properties of fluids and surfaces on the microscale, and interacting with photonic and magnetic fields. But

Rodney Ray Agayan

2008-01-01

274

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

2013-06-17

275

Detection of Magnetic Nanoparticles Using the Second-Harmonic Signal  

Microsoft Academic Search

We developed a detection system for magnetic nanoparticles (MNPs) using the second-harmonic signal. By measuring the secondharmonic signal from MNPs, we can significantly reduce the interference of the excitation field, compared to the case of measuring the fundamental signal. First, we explored the properties of harmonic signals from MNPs when both a DC bias field and an AC field were

Takashi Yoshida; Kotaro Ogawa; Takuya Tsubaki; Nurmiza Binti Othman; Keiji Enpuku

2011-01-01

276

Magnetic nanoparticle properties and microstructure formation in liquid dispersions  

Microsoft Academic Search

The physical properties and microstructures of magnetite and cobalt ferrite nanoparticles, dispersed in liquid matrices, are studied. Qualitative and quantitative analyses of static magnetization curves were performed. Magneto-granulometric results were obtained and interactions and agglomerations were evidenced, as a function of the preparation techniques as well as carrier liquids and surfactants used

L. V. M. Rasa; D. Bica

2000-01-01

277

Sensitive High Frequency AC Susceptometry in Magnetic Nanoparticle Applications  

NASA Astrophysics Data System (ADS)

We report on the development of a sensitive high frequency susceptometer capable of measuring in the frequency range from 25 kHz up to 10 MHz with a volume susceptibility sensitivity of 3.5×l0-5 at 100 kHz corresponding to about 0.3% of the measured AC susceptibility. In combination with the previous reported DynoMag system capable of measuring dynamic magnetic properties in the range from 1 Hz to 200 kHz we are thus able to measure dynamic magnetic properties between 1 Hz to 10 MHz with high magnetic sensitivity. We will show AC susceptometry applications and results within the fields of magnetic hyperthermia and dynamic magnetic characterization of magnetic nanoparticle system with different particle sizes and magnetic properties.

Ahrentorp, Fredrik; Astalan, Andrea P.; Jonasson, Christian; Blomgren, Jakob; Qi, Bin; Mefford, Olin Thompson; Yan, Minhao; Courtois, Jérémie; Berret, Jean-François; Fresnais, Jérôme; Sandre, Olivier; Dutz, Silvio; Müller, Robert; Johansson, Christer

2010-12-01

278

Chemical conjugation of urokinase to magnetic nanoparticles for targeted thrombolysis.  

PubMed

Thrombolytic therapy is an important treatment for thrombosis, a life-threatening condition in cardiovascular diseases. However, the traditional thrombolytic therapies have often been associated with the risk of severe bleeding. By conjugating urokinase with magnetic nanoparticles (MNPs), we have presented a strategy to control thrombolysis within a specific site. The covalent bioconjugate of urokinase and dextran-coated MNPs was synthesized and isolated. Thrombolysis by the conjugate was studied under a magnetic field in a rat arteriovenous shunt thrombosis model. The magnetic field was generated by two AlNiCo permanent magnets around the site of thrombus. The magnetic field enhanced the thrombolytic efficacy of the conjugate by 5-fold over urokinase with no reduction in plasma fibrinogen and little prolonged bleeding time. It suggested that thrombolysis had been specifically directed to the desired site by the magnetic carrier under the magnetic field. Additionally, the conjugate had a longer half-life than urokinase in circulation. PMID:19560812

Bi, Feng; Zhang, Jing; Su, Yijing; Tang, Yan-Chun; Liu, Jian-Ning

2009-06-27

279

Inter- and Intraparticle Interactions in Magnetic Nanoparticle Systems  

NASA Astrophysics Data System (ADS)

We investigated deviations of magnetic nanoparticle behavior from the ideal, non-interacting behavior in the superferromagnetic regime. These deviations can be understood in greater detail by considering the magnetic components oriented orthogonally to the applied magnetic field. We demonstrated the novel measurement of the transverse magnetization of 7 nm iron oxide crystals and showed that it agrees qualitatively with the deviations between proposed interaction models and our experimental, longitudinal magnetization curves. Using polarization analyzed small angle neutron scattering (PASANS), we demonstrated the ability to probe the 3D magnetic structure in a sample of 9 nm iron oxide nanoparticle crystals, and discovered a 1.0 to 1.5 nm thick shell with the spins coherently oriented perpendicular to a 7 nm core aligned with the applied field, between temperatures of 160 K and 320 K under a nominally saturating 1.2 T field. Finally, we developed a novel synthesis for of highly monodisperse, 30 nm diameter MnO nanoparticles. These were oxidized to create an Mn3O4 shell of controllable thickness. We found the exchange bias parameters in this MnO/Mn3O4 core/shell system to be significantly lower than those commonly reported for the same system. We believe the anomalous literature values to be due to spin-glass like behavior and/or thermal training resulting from the use of poorly crystalline, or polycrystalline particles.

Booth, Ryan Anderson

280

Computational studies of steering nanoparticles with magnetic gradients  

NASA Astrophysics Data System (ADS)

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

Aylak, Sultan Suleyman

281

Design and synthesis of plasmonic magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Core shell nanoparticles containing both iron oxide and gold are proposed for bioseparation applications. The surface plasmon resonance of gold makes it possible to track the positions of individual particles, even when they are smaller than the optical diffraction limit. The synthesis of water-dispersible iron oxide-gold nanoparticles is described. Absorption spectra show the plasmon peaks for Au shells on silica particles, suggesting that thin shells may be sufficient to impart a strong surface plasmon resonance to iron oxide-gold nanoparticles. Dark field optical microscopy illustrates the feasibility of single-particle detection. Calculations of magnetophoretic and drag forces for particles of different sizes reveal design requirements for effective separation of these small particles.

Lim, Jitkang; Tilton, Robert D.; Eggeman, Alexander; Majetich, Sara A.

2007-04-01

282

Immobilizing silver nanoparticles onto the surface of magnetic silica composite to prepare magnetic disinfectant with enhanced stability and antibacterial activity  

Microsoft Academic Search

In this article, silver nanoparticles inlaid Fe3O4–SiO2 magnetic composite (Fe3O4–SiO2–Ag) was successfully synthesized and its potential application as an antibacterial material in water disinfection was investigated. Silver nanoparticles, with diameter of about 10nm, were anchored homogeneously and tightly onto the silica coat of Fe3O4–SiO2 magnetic nanoparticles, which increased the antibacterial abilities by avoiding the aggregation of Ag nanoparticles. The minimum

Xiaole Zhang; Hongyun Niu; Jinping Yan; Yaqi Cai

2011-01-01

283

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

PubMed

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 10nm to 20 nm, and the nanoparticles suspending in the aqueous solution could easily aggregate by a magnet, which suggested that the nanoparticles had good magnetic characteristics. The BSA adsorption experiment indicated that when pH of BSA solution was equal to 4, the maximum adsorption loading reached 110 mg/g. Through measuring the zeta potential of BSA solution and the magnetic nanoparticles, it was found that under this situation the surface of BSA took the negative charge, but the magnetic nanoparticles took the positive charge. Due to the small diameter, the adsorption equilibrium of BSA onto the nanoparticles reached very quickly within 10 min. The adsorption equilibrium of BSA onto the magnetic chitosan nanoparticles fitted well with the Freundlich model. The experimental results showed that the magnetic chitosan nanoparticles have potential to be used for the quick pretreatment in the protein analysis process. PMID:17892932

Wang, Yujun; Wang, Xianghua; Luo, Guangsheng; Dai, Youyuan

2007-09-24

284

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

2011-02-01

285

Multifunctional Magnetic-Optical Nanoparticle Probes for Simultaneous Detection, Separation, and Thermal Ablation of Multiple Pathogens  

Microsoft Academic Search

Multifunctional nanoparticles possessing magnetization and near-infrared (NIR) absorption have warranted interest due to their significant applications in magnetic resonance imaging, diagnosis, bioseparation, target delivery, and NIR photothermal ablation. Herein, the site-selective assembly of magnetic nanoparticles onto the ends or ends and sides of gold nanorods with different aspect ratios (ARs) to create multifunctional nanorods decorated with varying numbers of magnetic

Chungang Wang; Joseph Irudayaraj

2010-01-01

286

Magnetic properties of multisegmented cylindrical nanoparticles with alternating magnetic wire and tube segments  

NASA Astrophysics Data System (ADS)

The magnetic properties in multisegmented cylindrical nanostructures comprised of nanowire and nanotube segments are investigated numerically as a function of their geometry. In this work we report systematic changes in the coercivity and remanence in these systems. Besides, we have found the ideal conditions for a magnetic configuration with two antiparallel domains that could be used to help to stabilize magnetic nanoparticles inside ferromagnetic multisegmented cylindrical nanoparticles. This magnetic behavior is due to the fact that the tube segment reverses its magnetization before the wire segment, allowing the control of the magnetic domain walls motion between two segments. In this way, these magnetic nanoobjects can be an alternative to store information or even perform logic functions.

Salazar-Aravena, D.; Corona, R. M.; Goerlitz, D.; Nielsch, K.; Escrig, J.

2013-11-01

287

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

PubMed Central

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

2011-01-01

288

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

NASA Astrophysics Data System (ADS)

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

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

2008-04-01

289

Affinity adsorption and separation behaviors of avidin on biofunctional magnetic nanoparticles binding to iminobiotin  

Microsoft Academic Search

Knowing the adsorption behavior of target proteins on biofunctional magnetic nanoparticles is of great importance for the separation and purification of proteins. Adsorption behaviors of avidin on biofunctional magnetic nanoparticles binding to iminobiotin were investigated under different conditions of temperature, pH, ionic strength, and feed avidin concentration. Biofunctionalization of the non-functional nanoparticles was performed, coupled with iminobiotin. Characterization of the

Shuguo Sun; Meihu Ma; Ning Qiu; Xi Huang; Zhaoxia Cai; Qun Huang; Xin Hu

2011-01-01

290

Synthesis of core-shell gold coated magnetic nanoparticles and their interaction with thiolated DNA  

Microsoft Academic Search

Core-shell magnetic nanoparticles have received significant attention recently and are actively investigated owing to their large potential for a variety of applications. Here, the synthesis and characterization of bimetallic nanoparticles containing a magnetic core and a gold shell are discussed. The gold shell facilitates, for example, the conjugation of thiolated biological molecules to the surface of the nanoparticles. The composite

Ian Robinson; Le D. Tung; Shinya Maenosono; Christoph Wälti; Nguyen T. K. Thanh

2010-01-01

291

Silica coating magnetic nanoparticle-based silver enhancement immunoassay for rapid electrical detection of ricin toxin  

Microsoft Academic Search

We developed a novel silica coating magnetic nanoparticle-based silver enhancement immunoassay (SEIA) for ricin toxin (RT) rapid electrical detection using interdigitated array microelectrodes (IDAMs) as electrodes. This novel system was developed by taking advantage of the separation and enrichment properties of magnetic nanoparticles (MNPs) and the catalytic properties of gold nanoparticles (GNPs). In this system, MNPs labeled with anti-ricin A

Jie Zhuang; Tao Cheng; Lizeng Gao; Yongting Luo; Quan Ren; Di Lu; Fangqiong Tang; Xiangling Ren; Dongling Yang; Jing Feng; Jingdong Zhu; Xiyun Yan

2010-01-01

292

Nanostructured diblock copolymer films with embedded magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Nanostructured diblock copolymer films with embedded magnetic nanoparticles are prepared by solution casting. The diblock copolymer polystyrene-block-polymethylmethacrylate with a fully deuterated polystyrene block of a weight ratio of 0.22 is used as a structure-directing matrix. Maghemite nanoparticles (?-Fe2O3) are coated with polystyrene and thus have a selective affinity to the minority block of the diblock copolymer. The hybrid film morphology is investigated as a function of nanoparticle concentration. The surface structure is probed with atomic force microscopy and scanning electron microscopy. The inner film structure and the structure at the polymer-substrate interface are detected with grazing incidence small angle neutron scattering (GISANS). Irrespective of the nanoparticle concentration a well developed micro-phase separation structure is present. From the Bragg peaks observed in the GISANS data a linear nanoparticle concentration dependence of the inter-domain spacing of the micro-phase separation structure is determined. The superparamagnetic and blocking behavior can be explained with a generalized Stoner-Wohlfarth-Néel theory which includes either an elastic torque being exerted on the nanoparticles by the field or a broad distribution of anisotropy constants.

Xia, Xin; Metwalli, Ezzeldin; Ruderer, Matthias A.; Körstgens, Volker; Busch, Peter; Böni, Peter; Müller-Buschbaum, Peter

2011-06-01

293

Orientational Order-Magnetization Coupling in Mixtures of Magnetic Nanoparticles and the Ferroelectric Liquid Crystal  

Microsoft Academic Search

We have studied the ferroelectric SmC* phase of SCE9 ferroelectric liquid crystal (LC) mixtures with magnetic nanoparticles (NPs). The impact of the NPs on the Goldstone and soft mode dielectric response has been determined by the dielectric spectroscopy measurements. The possible indirect coupling between the magnetic moments and the electrical polarization has been verified by measuring the impact of the

B. Roži?; M. Jagodi?; S. Gyergyek; M. Drofenik; S. Kralj; G. Lahajnar; Z. Jagli?i?; Z. Kutnjak

2010-01-01

294

Magnetic particle hyperthermia: Néel relaxation in magnetic nanoparticles under circularly polarized field  

Microsoft Academic Search

The mechanism of magnetization reversal in single-domain ferromagnetic particles is of interest in many applications, in most of which losses must be minimized. In cancer therapy by hyperthermia the opposite requirement prevails: the specific loss power should be maximized. Of the mechanisms of dissipation, here we study the effect of Néel relaxation on magnetic nanoparticles unable to move or rotate

P F de Châtel; I Nándori; J Hakl; S Mészáros; K Vad

2009-01-01

295

Magnetic response of mitochondria-targeted cancer cells with bacterial magnetic nanoparticles.  

PubMed

We first demonstrate the effects of magnetic trapping of mitochondria using aptamer conjugated to bacterial magnetic nanoparticles that allowed targeting of the mitochondrial cytochrome c in the treatment of cancer cells. Our findings offer a new approach for targeted cell therapy, with the advantage of remote control over subcellular elements. PMID:22728544

Choi, Jungin; Shin, Jaeha; Lee, Junghoon; Cha, Misun

2012-06-25

296

Metal nanoparticle fluids with magnetically induced electrical switching properties.  

PubMed

We report the successful preparation of solvent-free metal nanoparticle (NP) fluids with multiple-functionalities, such as rheological properties, magnetism, ionic conductivity, and electrical properties, allowing for facile synthesis and mass production. The gold nanoparticles (AuNPs) used in this study were synthesized using tetraoctylammonium bromide (TOABr) in toluene and then directly phase-transferred to solvent-free low-molecular-weight (Mw) imidazolium-type ionic liquid media containing thiol groups (i.e., IL-SH). Magnetic metal fluids (i.e., MIL-SH-AuNPs) were prepared by the addition of FeCl3 powder to metal fluids (i.e., IL-SH-AuNPs). These fluids showed relatively high ionic and electrical conductivities compared with those of conventional metal NP fluids based on organic ILs with high Mw. Furthermore, it was demonstrated that these fluids could be used as electric switches operated using an external magnetic field in organic media. PMID:23624685

Kim, Younghoon; Cho, Jinhan

2013-04-26

297

Thermal fluctuations of magnetic nanoparticles: Fifty years after Brown  

NASA Astrophysics Data System (ADS)

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

Coffey, William T.; Kalmykov, Yuri P.

2012-12-01

298

Acid-Sensitive Magnetic Nanoparticles as Potential Drug Depots  

PubMed Central

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

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

2011-01-01

299

Magnetic characterization and self-heating of various magnetic nanoparticles for medical applications  

Microsoft Academic Search

Magnetic and self-heating properties of CoFe2O4, MgFe2O4 and NiFe2O4 nanoparticles were evaluated. MgFe2O4 and NiFe2O4, whose coercive forces are lower than that of CoFe2O4, exhibited higher temperature rise in self-heating excited by ac magnetic field of 150 Oe at 10 kHz. The energy efficiency of magnetic field in generating self heating of these ferrite nanoparticles is also analyzed. It was

A. Tomitaka; H. Kobayashi; T. Yamada; Minhong Jeun; Seongtae Bae; Y. Takemura

2010-01-01

300

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

301

Aggregation behaviour of magnetic nanoparticle suspensions investigated by magnetorelaxometry  

NASA Astrophysics Data System (ADS)

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

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

2006-09-01

302

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

303

Direct cell entry of gold\\/iron-oxide magnetic nanoparticles in adenovirus mediated gene delivery  

Microsoft Academic Search

Gold\\/iron-oxide MAgnetic Nanoparticles (GoldMAN) imparts useful magnetic properties to various biomolecules. Gold nanoparticles immobilized on the surface of magnetic nanoparticles allow for the conjugation of biomolecules via an Au–S bond. Here, we present a practical application by utilizing GoldMAN and a magnetic field to induce intracellular transduction. This method has great potential for application of the adenovirus gene delivery vector

Kazumasa Kamei; Yohei Mukai; Hiroki Kojima; Tomoaki Yoshikawa; Mai Yoshikawa; George Kiyohara; Takao A. Yamamoto; Yasuo Yoshioka; Naoki Okada; Satoshi Seino; Shinsaku Nakagawa

2009-01-01

304

Comparative study of various magnetic nanoparticles for Cr(VI) removal  

Microsoft Academic Search

In this study, various magnetic nanoparticles were prepared by chemical co-precipitation method and used for the removal of Cr(VI) from synthetic electroplating wastewater. The size of these magnetic nanoparticles was measured using transmission electron microscopy (TEM) and found to be about 20nm. Their magnetic properties were characterized by vibrating sample magnetometer (VSM). The technical feasibility of magnetic nanoparticles for Cr(VI)

Jing Hu; Irene M. C. Lo; Guohua Chen

2007-01-01

305

Magnetic field intensified bi-enzyme system with in situ cofactor regeneration supported by magnetic nanoparticles.  

PubMed

Efficient dynamic interactions among cofactor, enzymes and substrate molecules are of primary importance for multi-step enzymatic reactions with in situ cofactor regeneration. Here we showed for the first time that the above dynamic interactions could be significantly intensified by exerting an external alternating magnetic field on magnetic nanoparticles-supported multi-enzymatic system so that the inter-particle collisions due to Brownian motion of nanoparticles could be improved. To that end, a multienzyme system including glutamate dehydrogenase (GluDH), glucose dehydrogenase (GDH) and cofactor NAD(H) were separately immobilized on silica coated Fe3O4 magnetic nanoparticles with an average diameter of 105nm, and the effect of magnetic field strength and frequency on the kinetics of the coupled bi-enzyme reaction was investigated. It was found that at low magnetic field frequency (25Hz and 100Hz), increasing magnetic field strength from 9.8 to 161.1Gs led to only very slight increase in reaction rate of the coupled bi-enzyme reaction expressed by glucose consumption rate. At higher magnetic field of 200Hz and 500Hz, reaction rate increased significantly with increase of magnetic field strength. When the magnetic field frequency was kept at 500Hz, the reaction rate increased from 3.89?M/min to 8.11?M/min by increasing magnetic field strength from 1.3 to 14.2Gs. The immobilized bi-enzyme system also showed good reusability and stability in the magnetic field (500Hz, 14.2Gs), that about 46% of original activity could be retained after 33 repeated uses, accounting for totally 34 days continuous operation. These results demonstrated the feasibility in intensifying molecular interactions among magnetic nanoparticle-supported multienzymes by using nano-magnetic stirrer for efficient multi-step transformations. PMID:23756150

Zheng, Muqing; Su, Zhiguo; Ji, Xiaoyuan; Ma, Guanghui; Wang, Ping; Zhang, Songping

2013-06-10

306

Magnetic nanoparticle transport within flowing blood and into surrounding tissue  

PubMed Central

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

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

2011-01-01

307

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

308

Thermodynamics of two-dimensional magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

A two-dimensional magnetic particle in the presence of an external magnetic field is studied. Equilibrium thermodynamical properties are derived by evaluating analytically the partition function. When the external field is applied perpendicular to the anisotropy axis the system exhibits a second-order phase transition with order parameter being the magnetization parallel to the field. In this case the system is isomorph to a mechanical system consisting of a particle moving without friction in a circle rotating about its vertical diameter. Contrary to a paramagnetic particle, equilibrium magnetization shows a maximum at finite temperature. It is also shown that uniaxial anisotropy in a system of noninteracting particles can be misinterpreted as a ferromagnetic or antiferromagnetic coupling among magnetic particles, depending on the angle between the anisotropy axes and magnetic field.

Vargas, P.; Altbir, D.; Knobel, M.; Laroze, D.

2002-05-01

309

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

PubMed Central

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 104by 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.

2009-01-01

310

The Submillimeter and Millimeter Excess of the Small Magellanic Cloud: Magnetic Dipole Emission from Magnetic Nanoparticles?  

NASA Astrophysics Data System (ADS)

The Small Magellanic Cloud (SMC) has surprisingly strong submillimeter- and millimeter-wavelength emission that is inconsistent with standard dust models, including those with emission from spinning dust. Here, we show that the emission from the SMC may be understood if the interstellar dust mixture includes magnetic nanoparticles, emitting magnetic dipole radiation resulting from thermal fluctuations in the magnetization. The magnetic grains can be metallic iron, magnetite Fe3O4, or maghemite ?-Fe2O3. The required mass of iron is consistent with elemental abundance constraints. The magnetic dipole emission is predicted to be polarized orthogonally to the normal electric dipole radiation if the nanoparticles are inclusions in larger grains. We speculate that other low-metallicity galaxies may also have a large fraction of the interstellar Fe in magnetic materials.

Draine, B. T.; Hensley, Brandon

2012-09-01

311

THE SUBMILLIMETER AND MILLIMETER EXCESS OF THE SMALL MAGELLANIC CLOUD: MAGNETIC DIPOLE EMISSION FROM MAGNETIC NANOPARTICLES?  

SciTech Connect

The Small Magellanic Cloud (SMC) has surprisingly strong submillimeter- and millimeter-wavelength emission that is inconsistent with standard dust models, including those with emission from spinning dust. Here, we show that the emission from the SMC may be understood if the interstellar dust mixture includes magnetic nanoparticles, emitting magnetic dipole radiation resulting from thermal fluctuations in the magnetization. The magnetic grains can be metallic iron, magnetite Fe{sub 3}O{sub 4}, or maghemite {gamma}-Fe{sub 2}O{sub 3}. The required mass of iron is consistent with elemental abundance constraints. The magnetic dipole emission is predicted to be polarized orthogonally to the normal electric dipole radiation if the nanoparticles are inclusions in larger grains. We speculate that other low-metallicity galaxies may also have a large fraction of the interstellar Fe in magnetic materials.

Draine, B. T.; Hensley, Brandon, E-mail: draine@astro.princeton.edu [Princeton University Observatory, Peyton Hall, Princeton, NJ 08544 (United States)

2012-09-20

312

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.

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

2013-01-01

313

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

314

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

315

Synthesis and characterization of magnetic nanoparticles and nano-composites  

NASA Astrophysics Data System (ADS)

This project involves a cationic surfactant assisted hydrothermal method for synthesizing magnetic manganite nanoparticles. We have demonstrated that manganite nanoparticles formed from a metal chloride precursor in water under mild hydrothermal conditions yields high crystalline, thermally stable and pure phase particles, whose sizes and morphology can also be tuned through adjustment of reaction temperature, precursor concentration, concentration of mineralizers and the presence of surfactants. Generally, stoichiometric LaxSr1-xMnO 3 (LSMO) nanoparticles were obtained at low process temperature of 240°C under the hydrothermal condition. Crystalline LSMO particles with grain size as small as 20 nm and confined to a narrow size distribution have been obtained. The nucleation and crystal growth processes mediated by macromolecule (CTAB) finally results in more uniform and controllable products. Based on these magnetic nano-sized perovskite manganites, we have systematically studied their magnetic hysteresis, magnetic anisotropy and exchange coupling. Several magnetometry techniques such as Zero Field-Cooled (ZFC)/Field-Cooled (FC) measurements, temperature dependent magnetization curve have been employed in these studies. A systematic study of the temperature dependence and the magnetic effects on electrical conductivity in LSMO nanoparticle has been made also. The experimental results were explained satisfactory by several scattering and hopping models. The composite consists of ferromagnetic La0.67Sr0.33 MnO3 core and antiferromagnetic LaMnO3 shell has been prepared. Formation of this manganites core-shell structure has been done by a two-step hydrothermal process, which involves the use of two precursor solutions in succession. We are able to show that a 5 nm thin layer is clearly coated on LSMO particles to form the desired core-shell architecture. The effects on the magnetic properties such as the coercive field enhancement are also discussed. Finally, LSMO/Poly(vinyl alcohol) (PVA) composites have been prepared by simple ultrasonic mixing of as-prepared nanoparticles and polymer solution. Then, films of LSMO/PVA composites have been fabricated on insulating substrate by traditional spin coating method. The microstructure, magnetic and magnetoresistivity properties of these films have been studied also. The experimental resistivity data of the present investigation are fitted to a simple empirical equation in order to reveal conduction mechanism in these composites.

Sin, Wai Lun

316

Detection of Iron–Oxide Magnetic Nanoparticles Using Magnetic Tunnel Junction Sensors With Conetic Alloy  

Microsoft Academic Search

We demonstrated the detection of 20-nm iron–oxide magnetic nanoparticles (MNPs) using Al O magnetic tunnel junction sensors (MTJs) with Conetic alloy. Conetic alloy Ni Fe Cu Mo was deposited as the MTJ free layer and pinned layer due to its magnetically soft properties. The magnetoresistance (MR) curves of MTJs with Conetic alloy showed tunneling magnetoresistance of 8.0% with small hysteresis

Z. Q. Lei; C. W. Leung; L. Li; G. J. Li; G. Feng; A. Castillo; P. J. Chen; P. T. Lai; P. W. T. Pong

2011-01-01

317

Room temperature magnetism in layered double hydroxides due to magnetic nanoparticles.  

PubMed

Some recent reports claiming room temperature spontaneous magnetization in layered double hydroxides (LDHs) have been published; however, the reported materials cause serious concern as to whether this cooperative magnetic behavior comes from extrinsic sources, such as spinel iron oxide nanoparticles. The syntheses of crystalline Fe(3+)-based LDHs with and without impurities have been developed, highlighting the care that must be taken during the synthetic process in order to avoid misidentification of magnetic LDHs. PMID:23795549

Abellán, Gonzalo; Carrasco, Jose A; Coronado, Eugenio

2013-06-24

318

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

319

Functionalized magnetic-fluorescent hybrid nanoparticles for cell labelling  

NASA Astrophysics Data System (ADS)

A facile method of synthesizing 60 nm magnetic-fluorescent core-shell bifunctional nanocomposites with the ability to label cells is presented. Hydrophobic trioctylphosphine oxide (TOPO)-capped CdSe@ZnS quantum dots (QDs) were assembled on polyethyleneimine (PEI)-coated Fe3O4 nanoparticles (MNP). Polyethyleneimine was utilized for the realization of multifunction, including attaching 4 nm TOPO capped CdSe@ZnS quantum dots onto magnetite particles, altering the surface properties of quantum dots from hydrophobic to hydrophilic as well as preventing the formation of large aggregates. Results show that these water-soluble hybrid nanocomposites exhibit good colloidal stability and retain good magnetic and fluorescent properties. Because TOPO-capped QDs are assembled instead of their water-soluble equivalents, the nanocomposites are still highly luminescent with no shift in the PL peak position and present long-term fluorescence stability. Moreover, TAT peptide (GRKKRRQRRRPQ) functionalized hybrid nanoparticles were also studied due to their combined magnetic enrichment and optical detection for cell separation and rapid cell labelling. A cell viability assay revealed good biocompatibility of these hybrid nanoparticles. The potential application of the new magnetic-fluorescent nanocomposites in biological and medicine is demonstrated.

Lou, Lei; Yu, Ke; Zhang, Zhengli; Li, Bo; Zhu, Jianzhong; Wang, Yiting; Huang, Rong; Zhu, Ziqiang

2011-05-01

320

Biofunctional magnetic nanoparticles as a general agent to immobilize proteins contained in traditional Chinese medicines  

Microsoft Academic Search

.  Maghemite nanoparticles were synthesized by the coprecipitation method. Silica was coated to the maghemite nanoparticles and\\u000a amino silane was modified to the surface of the silica magnetic nanoparticles. We use the biofunctional magnetic nanoparticles\\u000a as a general agent to immobilize and separate the proteins in a broad range from different traditional Chinese medicines.\\u000a The transmission electron microscopy results showed that

Hebai Shen; Wei Chen; Jing Li; Xingyu Li; Haifeng Yang

2007-01-01

321

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

NASA Astrophysics Data System (ADS)

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

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

2011-07-01

322

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

PubMed

When using magnetic nanoparticles as a heating source for magnetic particle hyperthermia it is of particular interest to know if the particles are free to move in the interstitial fluid or are fixed to the tumour tissue. The immobilization state determines the relaxation behaviour of the administered particles and thus their specific heating power. To investigate this behaviour, magnetic multicore nanoparticles were injected into experimentally grown tumours in mice and magnetic heating treatment was carried out in an alternating magnetic field (H = 25 kA m(-1), f = 400 kHz). The tested particles were well suited for magnetic heating treatment as they heated a tumour of about 100 mg by about 22 K within the first 60 s. Upon sacrifice, histological tumour examination showed that the particles form spots in the tissue with a mainly homogeneous particle distribution in these spots. The magnetic ex vivo characterization of the removed tumour tissue gave clear evidence for the immobilization of the particles in the tumour tissue because the particles in the tumour showed the same magnetic behaviour as immobilized particles. Therefore, the particles are not able to rotate and a temperature increase due to Brown relaxation can be neglected. To accurately estimate the heating potential of magnetic materials, the respective environments influencing the nanoparticle mobility status have to be taken into account. PMID:21576784

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

2011-05-17

323

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

324

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

PubMed Central

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

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

2010-01-01

325

Synthesis of core-shell gold coated magnetic nanoparticles and their interaction with thiolated DNA.  

PubMed

Core-shell magnetic nanoparticles have received significant attention recently and are actively investigated owing to their large potential for a variety of applications. Here, the synthesis and characterization of bimetallic nanoparticles containing a magnetic core and a gold shell are discussed. The gold shell facilitates, for example, the conjugation of thiolated biological molecules to the surface of the nanoparticles. The composite nanoparticles were produced by the reduction of a gold salt on the surface of pre-formed cobalt or magnetite nanoparticles. The synthesized nanoparticles were characterized using ultraviolet-visible absorption spectroscopy, transmission electron microscopy, energy dispersion X-ray spectroscopy, X-ray diffraction and super-conducting quantum interference device magnetometry. The spectrographic data revealed the simultaneous presence of cobalt and gold in 5.6±0.8 nm alloy nanoparticles, and demonstrated the presence of distinct magnetite and gold phases in 9.2±1.3 nm core-shell magnetic nanoparticles. The cobalt-gold nanoparticles were of similar size to the cobalt seed, while the magnetite-gold nanoparticles were significantly larger than the magnetic seeds, indicating that different processes are responsible for the addition of the gold shell. The effect on the magnetic properties by adding a layer of gold to the cobalt and magnetite nanoparticles was studied. The functionalization of the magnetic nanoparticles is demonstrated through the conjugation of thiolated DNA to the gold shell. PMID:20967339

Robinson, Ian; Tung, Le D; Maenosono, Shinya; Wälti, Christoph; Thanh, Nguyen T K

2010-10-21

326

Enhanced Magnetic Properties in Nanoparticle-Filled CNTs  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

327

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

2013-04-11

328

Magnetic Nanoparticles in the Interstellar Medium: Emission Spectrum and Polarization  

NASA Astrophysics Data System (ADS)

The presence of ferromagnetic or ferrimagnetic nanoparticles in the interstellar medium would give rise to magnetic dipole radiation at microwave and submillimeter frequencies. Such grains may account for the strong millimeter-wavelength emission observed from a number of low-metallicity galaxies, including the Small Magellanic Cloud. We calculate the absorption and scattering cross sections for such grains, with particular attention to metallic Fe, magnetite Fe3O4, and maghemite ?-Fe2O3, all potentially present in the interstellar medium. The rate of Davis-Greenstein alignment by magnetic dissipation is also estimated. We determine the temperature of free-flying magnetic grains heated by starlight and calculate the polarization of the magnetic dipole emission from both free-fliers and inclusions. For inclusions, the magnetic dipole emission is expected to be polarized orthogonally relative to the normal electric dipole radiation. Magnetic dipole radiation will contribute significantly to the 20-40 GHz anomalous microwave emission only if a large fraction of the Fe is in metallic Fe iron nanoparticles with extreme elongations. Finally, we present self-consistent dielectric functions for metallic Fe, magnetite Fe3O4, and maghemite ?-Fe2O3, enabling calculation of absorption and scattering cross sections from microwave to X-ray wavelengths.

Draine, B. T.; Hensley, Brandon

2013-03-01

329

Using polymers to make up magnetic nanoparticles for biomedicine.  

PubMed

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

Chanana, Munish; Mao, Zhengwei; Wang, Dayang

2009-12-01

330

How the size distribution of magnetic nanoparticles determines their magnetic particle imaging performance  

NASA Astrophysics Data System (ADS)

Spatial and temporal resolution of magnetic particle imaging (MPI), a powerful technique for biomedical imaging, depends crucially on the magnetic properties of the magnetic nanoparticle (MNP) tracer. The authors establish the relation of the static and the dynamic magnetization behavior of various MNP preparations to their MPI performance. While MNPs with a mean diameter of 6 nm achieve only 0.2% of the theoretical maximum amplitude of the third harmonic (at 25 kA/m drive field strength), those with 19 nm diameter attain 57%. The good performance of Resovist, a clinically approved contrast agent for magnetic resonance imaging, is explained by the presence of MNP aggregates.

Eberbeck, D.; Wiekhorst, F.; Wagner, S.; Trahms, L.

2011-05-01

331

Electrochemical synthesis of magnetic iron oxide nanoparticles with controlled size.  

PubMed

We present a novel and facile method enabling synthesis of iron oxide nanoparticles, which are composed mainly of maghemite according to X-ray diffraction (XRD) and Mössbauer spectroscopy studies. The proposed process is realized by anodic iron polarization in deaerated LiCl solutions containing both water and ethanol. Water seems to play an important role in the synthesis. Morphology of the product was studied by means of transmission electron microscopy and XRD. In the solution containing almost 100% of water a black suspension of round shaped maghemite nanoparticles of 20-40 nm size is obtained. Regulating water concentration allows to control nanoparticle size, which is reduced to 4-6 nm for 5% of water with a possibility to reach intermediate sizes. For 3% or lower water concentration nanoparticles are of a needle-like shape and form a reddish suspension. In this case phase determination is problematic due to a small particle size with the thickness of roughly 3 nm. However, XRD studies indicate the presence of ferrihydrite. Coercivities of the materials are similar to those reported for nanoparticle magnetite powders, whereas the saturation magnetization values are considerably smaller. PMID:22207821

Starowicz, Maria; Starowicz, Pawe?; Zukrowski, Jan; Przewo?nik, Janusz; Lema?ski, Andrzej; Kapusta, Czes?aw; Bana?, Jacek

2011-11-27

332

Magnetic nanoparticle-induced hyperthermia treatment under magnetic resonance imaging  

Microsoft Academic Search

Super paramagnetic iron oxide Fe3O4 nanoparticles prepared via photochemical reaction in pure form were used for inducing hyperthermia to treat subcutaneous Ehrlich carcinoma implanted in female mice. Our results indicate that the mean temperature profiles at the rectum, periphery of the tumor surface and at the center of the tumor during hyperthermia treatment increased gradually. The maximum temperature achieved in

Alsayed A. M. Elsherbini; Mahmoud Saber; Mohamed Aggag; Ahmed El-Shahawy; Hesham A. A. Shokier

2011-01-01

333

The effects of magnetic nanoparticle properties on magnetic fluid hyperthermia  

Microsoft Academic Search

Magnetic fluid hyperthermia (MFH) is a noninvasive treatment that destroys cancer cells by heating a ferrofluid-impregnated malignant tissue with an ac magnetic field while causing minimal damage to the surrounding healthy tissue. The strength of the magnetic field must be sufficient to induce hyperthermia but it is also limited by the human ability to safely withstand it. The ferrofluid material

Ravi Kappiyoor; Monrudee Liangruksa; Ranjan Ganguly; Ishwar K. Puri

2010-01-01

334

Magnetic Nanoparticle-Phospholipid Interactions in Monolayer Films  

NASA Astrophysics Data System (ADS)

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 monolayer can be used as a biomimetic model for MNP-phospholipid interactions. Monolayer studies have been conducted using 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and varying concentrations of MNPs. The MNPs are magnetite nanoparticles stabilized by triblock copolymers. These copolymer coatings are comprised of poly(ethylene oxide) (PEO) tail blocks with a short carboxylic acid-functionalized urethane central block. Isotherm studies and Brewster angle microscopy (BAM) are used to examine the phase behavior within the monolayer.

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

2003-03-01

335

Elastic torsion effects in magnetic nanoparticle diblock-copolymer structures  

NASA Astrophysics Data System (ADS)

Magnetic properties of thin composite films, consisting of non-interacting polystyrene-coated ?-Fe2O3 (maghemite) nanoparticles embedded into polystyrene-block-polyisoprene P(S-b-I) diblock-copolymer films are investigated. Different particle concentrations, ranging from 0.7 to 43 wt%, have been used. The magnetization measured as a function of external field and temperature shows typical features of anisotropic superparamagnets including a hysteresis at low temperatures and blocking phenomena. However, the data cannot be reconciled with the unmodified Stoner-Wohlfarth-Néel theory. Applying an appropriate generalization we find evidence for either an elastic torque being exerted on the nanoparticles by the field or a broad distribution of anisotropy constants.

Schulz, L.; Schirmacher, W.; Omran, A.; Shah, V. R.; Böni, P.; Petry, W.; Müller-Buschbaum, P.

2010-09-01

336

Preparation and Characterization of Stimuli-Responsive Magnetic Nanoparticles  

PubMed Central

In this work, the main attention was focused on the synthesis of stimuli-responsive magnetic nanoparticles (SR-MNPs) and the influence of glutathione concentration on its cleavage efficiency. Magnetic nanoparticles (MNPs) were first modified with activated pyridyldithio. Then, MNPs modified with activated pyridyldithio (MNPs-PDT) were conjugated with 2, 4-diamino-6-mercaptopyrimidine (DMP) to form SR-MNPs via stimuli-responsive disulfide linkage. Fourier transform infrared spectra (FTIR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize MNPs-PDT. The disulfide linkage can be cleaved by reduced glutathione (GHS). The concentration of glutathione plays an important role in controlling the cleaved efficiency. The optimum concentration of GHS to release DMP is in the millimolar range. These results had provided an important insight into the design of new MNPs for biomedicine applications, such as drug delivery and bio-separation.

2008-01-01

337

Preparation and characterization of magnetic nanoparticles coated with polyethylene glycol  

NASA Astrophysics Data System (ADS)

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

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

2009-09-01

338

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

Microsoft Academic Search

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

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

2004-01-01

339

Multiferroic Behaviour in Mixtures of the Ferroelectric Liquid Crystal and Magnetic Nanoparticles  

Microsoft Academic Search

A dielectric spectroscopy, magnetic susceptibility and high resolution calorimetry have been carried out in the vicinity of the ferroelectric smectic C* phase of SCE9 ferroelectric liquid crystal (LC) mixtures with magnetic nanoparticles (NPs) to determine the impact of the magnetic nanoparticles on the Goldstone and soft mode and to study the disordering effects on the ferroelectric phase transition. It was

B. Roži?; M. Jagodi?; S. Gyergyek; M. Drofenik; S. Kralj; G. Cordoyiannis; Z. Kutnjak

2011-01-01

340

Nearly complete regression of tumors via collective behavior of magnetic nanoparticles in hyperthermia  

Microsoft Academic Search

One potential cancer treatment selectively deposits heat to the tumor through activation of magnetic nanoparticles inside the tumor. This can damage or kill the cancer cells without harming the surrounding healthy tissue. The properties assumed to be most important for this heat generation (saturation magnetization, amplitude and frequency of external magnetic field) originate from theoretical models that assume non-interacting nanoparticles.

C. L. Dennis; A. J. Jackson; J. A. Borchers; P. J. Hoopes; R. Strawbridge; A. R. Foreman; J. van Lierop; C. Grüttner; R. Ivkov

2009-01-01

341

Effect of Magnetic Nanoparticles and Their Functionalization on Liquid Crystal Order  

Microsoft Academic Search

We have added magnetic nanoparticles with a different surface termination (functionalization) to smectic A 8CB liquid crystals and studied their effects on the order of the liquid crystal. This is done by looking at the liquid crystals both with polarized optical microscopy and by X-ray scattering. Adding the magnetic nanoparticles improves the liquid crystal's response to a magnetic field by

L. J. Martínez-Miranda; Kevin Mccarthy; L. K. Kurihara; A. Noel

2005-01-01

342

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

Microsoft Academic Search

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

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

2010-01-01

343

Characterisation and intrinsic magnetic resonance properties of nickel nanoparticles  

Microsoft Academic Search

Nickel nanoparticles have been extensively characterised by atomic force microscopy (AFM), scanning electron microscopy (SEM) and confocal micro-Raman spectroscopy. AFM underestimates the particle size compared to SEM measurements. It is shown that Raman spectroscopy can detect the nanometre-thick NiO layer on the particles having frequency shifts of the modes indicative of phonon confinement. The magnetic properties of the particles are

Frank J. Owens; V. Stepanov

2008-01-01

344

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.

2012-01-01

345

Magnetic properties of polypyrrole-coated iron oxide nanoparticles  

Microsoft Academic Search

Iron oxide nanoparticles were prepared using the sol-gel process. In situ polymerization of a pyrrole monomer in the presence of oxygen in an iron oxide-ethanol suspension resulted in an iron oxide polypyrrole nanocomposite. The structure and magnetic properties of the nanocomposites with varying pyrrole concentrations are investigated. X-ray diffraction studies indicate the presence of the gamma-Fe2O3 phase for the concentrations

Raksha Sharma; Subhalakshmi Lamba; S. Annapoorni

2005-01-01

346

Heterogeneous distribution of magnetic nanoparticles in reactive polymer blends  

Microsoft Academic Search

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

Guozhang Wu; Xiaoxia Cai; Xiaojie Lin; Hiroshi Yui

2010-01-01

347

Targeted thrombolysis by using of magnetic mesoporous silica nanoparticles.  

PubMed

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

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

2012-08-01

348

Nonlinear Phenomena in Magnetic Nanoparticle Systems at Microwave Frequencies  

Microsoft Academic Search

Nonlinear interactions of electromagnetic waves (EMW) in magnetic nanoparticle systems at microwave frequencies were numerically simulated using rigorous mathematical models to solve the nonlinear diffraction boundary problem. The transmission coefficients |S12| of arrays of ferrite spheres, depending on the normalized frequency omega\\/gamma (gamma gyromagnetic ratio), for radii of 250 mm and 0.1 mm, and separation between the spheres from 600

Martha Pardavi-Horvath; Galina S. Makeeva; Oleg A. Golovanov

2008-01-01

349

Role of anisotropy and interactions in magnetic nanoparticle systems  

Microsoft Academic Search

.  Magnetic nanoparticle systems are characterized by several competing effects like anisotropy, an inherent disorder, the long\\u000a range dipolar and the short range exchange interactions due to clustering effects. The sensitivity of the observed static\\u000a and dynamical properties of these systems like the blocking temperature, the hysteresis and the susceptibility, to the methods\\u000a of preparation, annealing and the resulting morphology is

R. Malik; S. Lamba; R. K. Kotnala; S. Annapoorni

2010-01-01

350

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

351

Uniaxial anisotropy and novel magnetic behaviors of CoFe2O4 nanoparticles prepared in a magnetic field  

NASA Astrophysics Data System (ADS)

CoFe2O4 nanoparticles prepared by chemical coprecipitation method in a magnetic field exhibit novel magnetic properties. The average particle diameter was about 2 nm and larger depending on the post annealing temperature. Magnetization measurements indicate that smaller nanoparticles are superparamagnetic above their respective blocking temperatures. In the blocked state, these nanoparticles exhibit interesting behaviors in the magnetic hysteresis measurements. Constricted, or wasp waisted with extremely narrow waist, hysteresis curves have been observed in the magnetization versus field sweeps. For larger nanoparticles, the room temperature hysteresis is typical of a ferromagnet with an open loop, but the loop closes at lower temperature. The novel magnetic behavior is attributed to the directional order of Co ions and vacancies in CoFe2O4 established during the coprecipitation of the nanoparticles under an applied field.

Gao, Qian; Hong, Guangyan; Ni, Jiazuan; Wang, Wendong; Tang, Jinke; He, Jibao

2009-04-01

352

Detection of DNA labeled with magnetic nanoparticles using MgO-based magnetic tunnel junction sensors  

NASA Astrophysics Data System (ADS)

We have demonstrated the detection of 2.5 ?M target DNA labeled with 16 nm Fe3O4 nanoparticles (NPs) and 50 nm commercial MACS™ NPs using arrays of magnetic tunnel junction sensors with (001)-oriented MgO barrier layers. Signal-to-noise ratios of 25 and 12 were obtained with Fe3O4 and MACS™ NPs, respectively. These data show conclusively that MgO-based MTJ sensor arrays are very promising candidates for future applications involving the accurate detection and identification of biomolecules tagged with magnetic nanoparticles.

Shen, Weifeng; Schrag, Benaiah D.; Carter, Matthew J.; Xie, Jin; Xu, Chenjie; Sun, Shouheng; Xiao, Gang

2008-04-01

353

Immobilization of glucose oxidase and lactate dehydrogenase onto magnetic nanoparticles for bioprocess monitoring system  

Microsoft Academic Search

Glucose oxidase (GOD) and lactate dehydrogenase (LDH) were immobilized onto magnetic nanoparticles, viz. Fe3O4, via carbodiimide and glutaraldehyde. The immobilization efficiency was largely dependent upon the immobilization time and\\u000a concentration of glutaraldehyde. The magnetic nanoparticles had a mean diameter of 9.3 nm and were superparamagnetic. The\\u000a immobilization of GOD and LDH on the nanoparticles slightly decreased their saturation magnetization. However,

Ok-Jae Sohn; Chun-Kwang Kim; Jong Il Rhee

2008-01-01

354

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

Microsoft Academic Search

This work reports the immobilization of monomeric, dimeric and trimer protein Gs onto silica magnetic nanoparticles for self-oriented antibody immobilization. To achieve this, we initially prepared the silica-coated magnetic nanoparticle having about 170 nm diameters. The surface of the silica coated magnetic nanoparticles was modified with 3- aminopropyl-trimethoxysilane (APTMS) to chemically link to multimeric protein Gs. The conjugation of amino

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

2011-01-01

355

Functionalized Magnetic Nanoparticles as an In Vivo Delivery System  

NASA Astrophysics Data System (ADS)

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

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

356

Silica coated magnetic nanoparticles for separation of nuclear acidic waste  

SciTech Connect

Fe{sub 2}O{sub 3} magnetic nanoparticles (MNPs) have been coated with silica, followed by covalent attachment of the actinide specific chelators to separate nuclear waste in acidic conditions. A general model is developed to relate the surface coating to the particle's magnetization change, providing an alternative way to characterize the size-distribution/aggregation of MNPs. The optimized silica coating protects the Fe{sub 2}O{sub 3} MNPs from iron leaching under highly acidic conditions, facilitates the dispersion of MNPs, and dramatically increases the loading capacity of chelator onto the MNPs. Compared with the uncoated counterparts, the silica coated MNPs show enhanced actinide separation efficiency.

Han, H.; Kaur, M.; Qiang, Y. [Department of Physics and Environmental Science, University of Idaho, Moscow, Idaho 83844 (United States); Johnson, A.; Paszczynski, A. [Environmental Biotechnology Institute, Molecular Biology and Biochemistry, University of Idaho, Moscow, Idaho 83844 (United States); Department of Microbiology, Molecular Biology and Biochemistry, University of Idaho, Moscow, Idaho 83844 (United States); Kaczor, J. [Environmental Biotechnology Institute, Molecular Biology and Biochemistry, University of Idaho, Moscow, Idaho 83844 (United States)

2010-05-15

357

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

PubMed

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

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

2012-05-01

358

Multifunctional fluorescent and magnetic nanoparticles for biomedical applications  

NASA Astrophysics Data System (ADS)

Hybrid multifunctional nanoparticles (NPs) are emerging as useful probes for magnetic based targeting, delivery, cell separation, magnetic resonance imaging (MRI), and fluorescence-based bio-labeling applications. Assessing from the literature, the development of multifunctional NPs for multimodality imaging is still in its infancy state. This report focuses on our recent work on quantum dots (QDs), magnetic NPs (MNPs) and bi-functional NPs (composed of either QDs or rare-earth NPs, and magnetic NPs - iron oxide or gadolinium oxide) for multimodality imaging based biomedical applications. The combination of MRI and fluorescence would ally each other in improving the sensitivity and resolution, resulting in improved and early diagnosis of the disease. The challenges in this area are discussed.

Selvan, Subramanian T.

2012-02-01

359

Magnetic Nanoparticles in MR Imaging and Drug Delivery  

PubMed Central

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

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

2009-01-01

360

The synthesis and bio-applications of magnetic and fluorescent bifunctional composite nanoparticles.  

PubMed

Magnetic-fluorescent composite nanoparticles as a new kind of nanoparticle have attracted much attention in recent years. The composite nanoparticles combine the fluorescent properties, magnetic properties and the physical properties of nano-size, so they can offer a range of potential applications, such as bioseparation and bio-imaging, tumor cell localization, and even cancer treatment. This Minireview will introduce the main synthesis strategies for the fabrication of magnetic-fluorescent composite nanoparticles, the current and potential bio-application of magnetic-fluorescent nanocomposites, including protein and DNA separation and detection, bio-imaging and sorting in vitro and in vivo, drug delivery and the cancer treatment. PMID:21431200

Wang, Guannan; Su, Xingguang

2011-03-23

361

The need for stable, mono-dispersed, and biofunctional magnetic nanoparticles for one-step magnetic immunoassays  

Microsoft Academic Search

We have developed a magnetic immunoassay system (MIA) using magnetic nanoparticle markers for biomolecule detection. We have magnetically characterized multi-core magnetic nanoparticles (MNPs) containing single-domain crystals of Fe3O4 and CoFe2O4 with our system using a high temperature superconducting quantum interference device as detector. We use a Helmholtz coil to excite the MNPs and study the AC-susceptibility. The data is fit

F. Öisjöen; J. F. Schneiderman; A. P. Astalan; A. Kalabukhov; C. Johansson; D. Winkler

2010-01-01

362

Magnetic Dipolar Interactions in Nanoparticle Systems: Theory, Simulations and Ferromagnetic Resonance  

Microsoft Academic Search

Magnetic nanoparticle assemblies present novel magnetic properties with respect to their bulk constituent components. In addition\\u000a to the surface effects produced by the modified atomic symmetry in such low dimensional systems, the magnetic coupling between\\u000a the particles also plays a significant role in determining the overall magnetic behavior of a magnetic nanoparticle assembly.\\u000a In this Chapter, we describe a theoretical

D. S. Schmool; M. Schmalzl

2008-01-01

363

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

364

Preparation of magnetic nanoparticles for magnetic fluid hyperthermia  

Microsoft Academic Search

In this paper, the determination and preparation of suitable magnetic material for magnetic fluid hyperthermia (MFH) is presented. It was suggested that the highest heating rate could be obtained by using maghemite with particle diameter of 15 nm. The heating rate of magnetite particle with diameter less than 10 nm was found to generate heat higher than that of cobalt

T. Atsumi; B. Jeyadevan; Y. Sato; K. Tamura; S. Aiba; K. Tohji

2005-01-01

365

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

PubMed

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

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

2012-10-01

366

Enhancing the tumor discrimination using antibody-activated magnetic nanoparticles in ultra-low magnetic fields  

NASA Astrophysics Data System (ADS)

In this paper, we report an enhanced liver tumor discrimination for rats using antibody-activated magnetic nanoparticles (MNs) and ultra-low-field magnetic resonance imaging ex vivo. It was found that the intensity ratio between the magnetic resonance image of tumor and normal liver tissues is 2-3 absence of antibody-activated MNs in rats. The intensity ratio rises to ~100 when antibody-activated MNs are expressed in liver tumors through vein injection. Enhancing tumor discrimination using antibody-activated MNs is demonstrated using T1-weighted contrast imaging in ultra-low magnetic fields.

Yang, H. C.; Huang, K. W.; Liao, S. H.; Horng, H. E.; Chieh, J. J.; Chen, H. H.; Chen, M. J.; Chen, K. L.; Wang, L. M.

2013-01-01

367

Magnetic polystyrene nanocomposites reinforced with black iron oxide nanoparticles  

NASA Astrophysics Data System (ADS)

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

Yan, Xingru

368

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

PubMed Central

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

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

2009-01-01

369

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.

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

2009-01-01

370

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

Microsoft Academic Search

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

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

2009-01-01

371

Dynamics of Magnetization Reversal in Models of Magnetic Nanoparticles and Ultrathin Films  

Microsoft Academic Search

We discuss numerical and theoretical results for models of magnetization switching in nanoparticles and ultrathin films. The\\u000a models and computational methods include kinetic Ising and classical Heisenberg models of highly anisotropic magnets which\\u000a are simulated by dynamic Monte Carlo methods, and micromagnetics models of continuum-spin systems that are studied by finite-temperature\\u000a Langevin simulations. The theoretical analysis builds on the fact

Per Arne Rikvold; Gregory Brown; Steven J. Mitchell; M. A. Novotny

372

Detection of carcinoembryonic antigen using functional magnetic and fluorescent nanoparticles in magnetic separators  

Microsoft Academic Search

We combined a sandwich immunoassay, anti-CEA\\/CEA\\/anti-CEA, with functional magnetic (~80 nm) and fluorescent (~180 nm) nanoparticles\\u000a in magnetic separators to demonstrate a detection method for carcinoembryonic antigen (CEA). Determination of CEA in serum\\u000a can be used in clinical diagnosis and monitoring of tumor-related diseases. The CEA concentrations in samples were deduced\\u000a and determined based on the reference plot using the measured fluorescent

H. Y. Tsai; C. Y. Chang; Y. C. Li; W. C. Chu; K. Viswanathan; C. Bor Fuh

2011-01-01

373

Synthesis and Characteraization of Fe3O4 Nanoparticles for Magnetic Hyperthermia Application  

NASA Astrophysics Data System (ADS)

The superparamagnetic magnetite (Fe3O4) nanoparticles were synthesized by microemulsion technique. The synthesized nanoparticles were 10 nm with good crystalline nature. The superparamagnetic property was observed from vibrating sample magnetometer study. Specific absorption (SAR) of the Fe3O4 nanoparticles were calculated for different AC magnetic field amplitude at constant frequency. Calculated SAR was found to be square field dependent.

Ramesh, R.; Ponnusamy, S.; Muthamizhchelvan, C.

2011-06-01

374

Preparation, structural and magnetic characterization of synthetic anti-ferromagnetic (SAF) nanoparticles  

Microsoft Academic Search

Synthetic anti-ferromagnetic nanoparticles (SAFs) are a novel type of magnetic nanoparticle (MNP) fabricated using nanoimprint lithography, direct deposition of multilayer films and retrieval in liquid phase via an 'etching' release process. Such physical fabrication techniques enable accurate control of particle shape, size and composition. We systematically varied the processing conditions to produce different configurations of SAF nanoparticles and performed extensive

A. L. Koh; W. Hu; R. J. Wilson; S. X. Wang; R. Sinclair

2008-01-01

375

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

PubMed

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

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

2010-03-26

376

Magnetic nanoparticle hyperthermia: predictive model for temperature distribution  

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

377

Magnetic metal nanoparticles coated polyacrylonitrile textiles as microwave absorber  

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

378

Labeled magnetic nanoparticles assembly on polypyrrole film for biosensor applications.  

PubMed

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

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

2008-01-03

379

Magnetic Nanoparticles and microNMR for Diagnostic Applications  

PubMed Central

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

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

2012-01-01

380

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

381

Metal nanoparticle fluids with magnetically induced electrical switching properties  

NASA Astrophysics Data System (ADS)

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

Kim, Younghoon; Cho, Jinhan

2013-05-01

382

Imaging of Her2-targeted magnetic nanoparticles for breast cancer detection: comparison of SQUID-detected magnetic relaxometry and MRI.  

PubMed

Both magnetic relaxometry and magnetic resonance imaging (MRI) can be used to detect and locate targeted magnetic nanoparticles, noninvasively 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. T(2)-weighted MRI yielded a detection limit of 15 600 cells in a 150 µl volume, with r(1) = 1.1 mm(-1) s(-1) and r(2) = 166 mm(-1) s(-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

383

Magnetic Nanoparticle based Solder Composites for Electronic Packaging Applications  

NASA Astrophysics Data System (ADS)

Rosensweig's model for power dissipation in ferrofluids when subjected to alternating magnetic fields was extended to account for the particle size distribution and temperature dependence of the magnetization parameters. The power loss and heating rates for various magnetic materials were compared to determine their suitability for technological and biomedical applications. Synthesis of FeCo magnetic nanoparticles (MNPs) for carried out using a RF plasma torch setup. Various samples of FeCo MNPs synthesized were characterized for their structural and magnetic properties. Their power loss ability in AC magnetic field of 50 mT at 280 kHz was evaluated using a RF heating station and infra-red thermal imaging setup. FeCo MNPs were incorporated into solder paste and their ability to cause solder reflow in AC magnetic field was demonstrated. The solder-MNP composite samples showed heating profile dependent on their size distribution. The highest heating rates were achieved for FeCo MNPs with average particle size of 50 nm. Suitability of RF reflow of solder-MNP composites for board level and flip chip electronic packaging applications has been explored by performing RF reflow experiments on flip-chip substrate. Microstructural evolution in the solder-MNP composites has been studies and its effects on the mechanical and electrical properties have been determined. FeCo MNPs help in nucleation of beta-Sn phase which helps to refine the eutectic microstructure during solidification. This results in improvement of their mechanical properties.

Habib, Ashfaque Hussian

384

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

385

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

386

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

387

A versatile platform for highly sensitive detection of protein: DNA enriching magnetic nanoparticles based rolling circle amplification immunoassay.  

PubMed

A novel rolling circle amplification (RCA) immunoassay based on DNA enriching magnetic nanoparticles and assembled fluorescent DNA nanotags, magnetic nanoparticles-RCA immunoassay, is developed as a versatile fluorescence assay platform for highly sensitive proteins detection. PMID:22301574

Xue, Qingwang; Wang, Lei; Jiang, Wei

2012-02-03

388

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

389

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

PubMed Central

Magnetic nanoparticles (MNP) are playing an increasingly important role in cardiovascular molecular imaging. These agents are superparamagnetic and consist of a central core of iron-oxide surrounded by a carbohydrate or polymer coat. The size, physical properties and pharmacokinetics of MNP make them highly suited to cellular and molecular imaging of atherosclerotic plaque and myocardial injury. MNP have a sensitivity in the nanomolar range and can be detected with T1, T2, T2*, off resonance and steady state free precession sequences. Targeted imaging with MNP is being actively explored and can be achieved through either surface modification or through the attachment of an affinity ligand to the nanoparticle. First generation MNP are already in clinical use and second generation agents, with longer blood half lives, are likely to be approved for routine clinical use in the near future.

Sosnovik, David E.; Nahrendorf, Matthias; Weissleder, Ralph

2008-01-01

390

Nanoparticle magnetization measurements by a high sensitive nano-superconducting quantum interference device  

NASA Astrophysics Data System (ADS)

A high sensitive nano superconducting quantum interference device (nanoSQUID) operating as a magnetic flux to critical current transducer with a suitable feedback circuit is employed to measure the magnetization of ferrimagnetic iron oxide nanoparticles. An improved SQUID responsivity has been obtained by using a loop inductance asymmetry. Iron oxide nanoparticles having a mean diameter of 8 nm have been excited by applying a polarizing field in the plane of the nanoSQUID loop. The field dependence of the nanoparticle magnetization at T = 4.2 K shows magnetic hysteresis. Magnetic relaxation measurements are reported and compared with those obtained by using a commercial measurement system.

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

2012-09-01

391

Magnetic relaxation in nano-particle stacks  

NASA Astrophysics Data System (ADS)

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

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

2005-01-01

392

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

PubMed

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

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

2013-03-18

393

Behavior of mixtures of nano-particles in magnetically assisted fluidized bed  

Microsoft Academic Search

Gas-fluidization of nano-particle mixtures in magnetically assisted fluidized bed (MAFB) has been investigated. Nano-particles undergoing fluidization exhibit two types of behavior: agglomerate particulate fluidization (APF) and agglomerate bubbling fluidization (ABF). Fluidization of sole SiO2 or ZnO nano-particles exhibits APF and ABF, respectively, but mixtures of them can be fluidized stably and almost homogenously. Stable fluidization of nano-particle mixtures can be

Ping Zeng; Tao Zhou; Jingsi Yang

2008-01-01

394

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

395

Effect of the surface coating on the magnetic nanoparticle smectic-A liquid crystal interaction  

NASA Astrophysics Data System (ADS)

The behavior of smectic-A liquid crystals with magnetic particles has not been very well characterized. The authors have studied the interaction of a smectic-A liquid crystal with magnetic nanoparticles. They concentrate on the effect of the particles' surface coating or functionalization compound. The surface coating in a nanoparticle is used to avoid phase separation and in biological applications to identify a particular cell or protein. Thus it is important to see how the surface coating interacts with the liquid crystal in conjunction with the magnetic nanoparticles. They have found out that depending on the surface coating the interaction of the nanoparticles with the liquid crystal varies. This variation is related to how the surface coating aligns the liquid crystal, how it contributes to the relative concentration of the nanoparticles in the liquid crystal-nanoparticle mixture, and how it affects the magnetic energy of the system.

Martínez-Miranda, L. J.; McCarthy, Kevin; Kurihara, L. K.; Harry, Jason J.; Noel, Alexis

2006-10-01

396

Synthesis, characterization and magnetic properties of nearly monodisperse CuCr2Se4 nanoparticles.  

PubMed

Nearly monodisperse CuCr(2)Se(4) hexagon-shaped nanoparticles with crystallite sizes from 15.1 to 24.3 nm were synthesized by thermal decomposition of metal chlorides and selenium powder in oleylamine. In addition, the 'flower'-shaped CuCr(2)Se(4) nanoparticles with a crystallite size 19.8 nm were also fabricated under similar conditions using heptanoic acid. Magnetic measurements show that all samples reveal ferromagnetic behavior below 350 K. The 'flower'-shaped nanoparticles have saturation magnetization, coercivity and remanent magnetization higher than the hexagon-shaped nanoparticles. However, the Curie temperature of the 'flower'-shaped nanoparticles (approximately 380 K) is somewhat lower than in the hexagon-shaped nanoparticles (420-430 K). These phenomena may be associated with the shape and surface anisotropy which would exert a tremendous influence on the particle's magnetic properties. PMID:20463392

Lin, Chun-Rong; Yeh, Cheng-Lung; Lu, Shih-Zong; Lyubutin, Igor S; Wang, Sheng-Chang; Suzdalev, Igor P

2010-05-13

397

Synthesis, characterization and magnetic properties of nearly monodisperse CuCr2Se4 nanoparticles  

NASA Astrophysics Data System (ADS)

Nearly monodisperse CuCr2Se4 hexagon-shaped nanoparticles with crystallite sizes from 15.1 to 24.3 nm were synthesized by thermal decomposition of metal chlorides and selenium powder in oleylamine. In addition, the 'flower'-shaped CuCr2Se4 nanoparticles with a crystallite size 19.8 nm were also fabricated under similar conditions using heptanoic acid. Magnetic measurements show that all samples reveal ferromagnetic behavior below 350 K. The 'flower'-shaped nanoparticles have saturation magnetization, coercivity and remanent magnetization higher than the hexagon-shaped nanoparticles. However, the Curie temperature of the 'flower'-shaped nanoparticles (?380 K) is somewhat lower than in the hexagon-shaped nanoparticles (420-430 K). These phenomena may be associated with the shape and surface anisotropy which would exert a tremendous influence on the particle's magnetic properties.

Lin, Chun-Rong; Yeh, Cheng-Lung; Lu, Shih-Zong; Lyubutin, Igor S.; Wang, Sheng-Chang; Suzdalev, Igor P.

2010-06-01

398

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

399

Towards a versatile platform based on magnetic nanoparticles for in vivo applications  

Microsoft Academic Search

Magnetic nanoparticles have attracted wide attention because of their usefulness as contrast agents for magnetic resonance\\u000a imaging (MRI) or colloidal mediators for cancer magnetic hyperthermia. This paper examines these in vivo applications through an understanding of the problems involved and the current and future possibilities for resolving them.\\u000a A special emphasis is made on magnetic nanoparticle requirements from a physical

E Duguet; S Vasseur; S Mornet; G Goglio; A Demourgues; J Portier; F Grasset; P Veverka; E Pollert

2006-01-01

400

Formation of magnetic Ni nanoparticles in x-ray irradiated electroless solution  

Microsoft Academic Search

Magnetic nanostructures are attracting tremendous interest as regards application in high-density data storage devices and magnetic fluids. We have prepared magnetic nanoparticles (similar to7.5 nm) by x-ray irradiation of electroless solutions and furthermore have investigated their structural and magnetic properties. Interestingly, we find that the formation of these Ni nanoparticles occurs spontaneously, during the room temperature process, dominantly at electrolyte

P. H. Borse; J. M. Yi; J. H. Je; S. D. Choi; Y. Hwu; P. Ruterana; G. Nouet

2004-01-01

401

Fe-nanoparticle coated anisotropic magnet powders for composite permanent magnets with enhanced properties  

NASA Astrophysics Data System (ADS)

Utilizing the chemical reduction of FeCl2 with NaBH4 in the presence of 2:17 Sm-Co powders, we synthesized composite Sm(Co0.699Fe0.213Cu0.064Zr0.024)7.4/nano-Fe anisotropic hard magnetic powders. The average particle size of the hard magnetic core powder was 21 ?m while the soft magnetic Fe nanoparticles deposited uniformly on the core powder had a particle size smaller than 100 nm. Different reaction protocols, such as immersion of the hard magnetic core powder in each reagent, the use of microemulsion (micelle) technique, or doubling the weight ratio of FeCl2 to core powder, led to different degrees of magnetic coupling of the hard and soft magnetic components of the composite powder. A reaction time of 180 s led to deposition of 3.5 wt % Fe nanoparticles and improved magnetic properties of the composite powder compared to the uncoated Sm(Co0.699Fe0.213Cu0.064Zr0.024)7.4 powder. The respective magnetic hysteresis parameters were 4?M18 kOe=11.3 kG, 4?Mr=11 kG, and iHc>20 kOe with a smooth demagnetization curve.

Marinescu, M.; Liu, J. F.; Bonder, M. J.; Hadjipanayis, G. C.

2008-04-01

402

Magnetic properties and heating effect in bacterial magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

A suspension of bacterial magnetosomes was investigated with respect to structural and magnetic properties and hyperthermic measurements. The mean particle diameter of about 35 nm was confirmed by transmission electron microscopy (TEM), X-ray and magnetic analysis. The X-ray powder diffraction peaks of magnetosomes fit very well with standard Fe3O4 reflections. The found value for specific absorption rate (SAR) of 171 W/g at 5 kA/m and 750 kHz means that magnetosomes may be considered as good materials for the biomedical applications in hyperthermia treatments. Moreover, they have biocompatible phospholipid membrane.

Timko, Milan; Dzarova, Anezka; Kovac, Jozef; Skumiel, Andrzej; Józefczak, Arkadiusz; Hornowski, Tomasz; Goj?ewski, Hubert; Zavisova, Vlasta; Koneracka, Martina; Sprincova, Adriana; Strbak, Oliver; Kopcansky, Peter; Tomasovicova, Natalia

2009-05-01

403

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

404

Magnetic and luminescent properties of multifunctional GdF3:Eu3+ nanoparticles  

Microsoft Academic Search

Multifunctional GdF3:Eu3+ nanoparticles were synthesized using a hydrothermal method. Photoluminescent excitation and emission spectra, and lifetime were measured. The average lifetime of the nanoparticles is about 11 ms. The nanoparticle exhibits paramagnetism at both 293 and 77 K, ascribing to noninteracting localized nature of the magnetic moment in the compound. The magnetic properties of GdF3:Eu3+ is intrinsic to the Gd3+

Hon-Tung Wong; H. L. W. Chan; J. H. Hao

2009-01-01

405

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

Microsoft Academic Search

A microfluidic device integrated with molecularly imprinted magnetic nanoparticles as stationary phase was designed for rapid enantioseparation by capillary electrochromatography. The nanoparticles were synthesized by the co-polymerization of methacrylic acid and ethylene glycol dimethacrylate on 3-(methacryloyloxy)propyltrimethoxysilane-functionalized magnetic nanoparticles (25-nm diameter) in the presence of template molecule, and characterized with infrared spectroscopy, thermal gravimetric analysis, and transmission electron microscope. The imprinted

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

2010-01-01

406

Structural and magnetic properties of core-shell iron-iron oxide nanoparticles  

Microsoft Academic Search

We present studies of the structural and magnetic properties of core-shell iron-iron oxide nanoparticles. alpha-Fe nanoparticles were fabricated by sputtering and subsequently covered with a protective nanocrystalline oxide shell consisting of either maghaemite (gamma-Fe2O3) or partially oxidized magnetite (Fe3O4). We observed that the nanoparticles were stable against further oxidation, and Mössbauer spectroscopy at high applied magnetic fields and low temperatures

L. Theil Kuhn; A. Bojesen; L. Timmermann; M. Meedom Nielsen; S. Mørup

2002-01-01

407

Structural and magnetic properties of core–shell iron–iron oxide nanoparticles  

Microsoft Academic Search

We present studies of the structural and magnetic properties of core–shell iron–iron oxide nanoparticles. ?-Fe nanoparticles were fabricated by sputtering and subsequently covered with a protective nanocrystalline oxide shell consisting of either maghaemite (?-Fe2O3) or partially oxidized magnetite (Fe3O4). We observed that the nanoparticles were stable against further oxidation, and Mössbauer spectroscopy at high applied magnetic fields and low temperatures

L Theil Kuhn; A Bojesen; L Timmermann; M Meedom Nielsen; S Mørup

2002-01-01

408

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

409

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

Microsoft Academic Search

A green one-step approach has been developed for the synthesis of amino-functionalized magnetite nanoparticles. The synthesis was accomplished by simply mixing FeCl2 with arginine under ambient conditions. It was found that the Fe2+\\/arginine molar ratio, reaction duration and temperature greatly influence the size, morphology and composition of magnetic nanoparticles. The arginine-stabilized magnetic nanoparticles were characterized by transmission electron microscopy, x-ray

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

2009-01-01

410

Effect of the surface coating on the magnetic nanoparticle smectic-A liquid crystal interaction  

Microsoft Academic Search

The behavior of smectic-A liquid crystals with magnetic particles has not been very well characterized. The authors have studied the interaction of a smectic-A liquid crystal with magnetic nanoparticles. They concentrate on the effect of the particles' surface coating or functionalization compound. The surface coating in a nanoparticle is used to avoid phase separation and in biological applications to identify

L. J. Martínez-Miranda; Kevin McCarthy; L. K. Kurihara; Jason J. Harry; Alexis Noel

2006-01-01

411

Effect of Magnetic Nanoparticles, Their Size and Functionalization on Liquid Crystal Order  

Microsoft Academic Search

We have observed the effects of adding magnetic nanoparticles with a different surface termination to smectic A 8CB liquid crystals by examining the liquid crystals both with polarized optical microscopy and by x-ray scattering. The smectic A liquid crystal is the phase we find in cell walls and other biological components. Adding the magnetic nanoparticles improves the liquid crystals' response

L. J. Martinez-Miranda; Kevin McCarthy; R. L. Bruce; L. K. Kurihara; Jason J. Harry; A. Noel

2005-01-01

412

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

Microsoft Academic Search

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

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

2010-01-01

413

Fabrication and magnetic properties of boron nitride nanocapsules encaging iron oxide nanoparticles  

Microsoft Academic Search

Boron nitride (BN) nanocapsules with iron oxide nanoparticles were fabricated by an arc discharge method, and the magnetic properties of these nanocapsules were investigated. High resolution electron microscopy showed that iron oxide nanoparticles of size 20nm were encapsulated by boron nitride sheets of width 4nm. Magnetization of the BN nanocapsules showed paramagnetism and the initial iron oxides showed ferromagnetism, which

Takanori Hirano; Takeo Oku; Katsuaki Suganuma

2000-01-01

414

Asymmetric hydrosilylation of ketones catalyzed by magnetically recoverable and reusable copper ferrite nanoparticles.  

PubMed

Herein we present magnetically recoverable and reusable copper ferrite nanoparticles for asymmetric hydrosilylation of several ketones. Up to 99% enantiometric excess was obtained at room temperature using polymethylhydrosiloxane as the stoichiometric reducing agent. The copper ferrite nanoparticles were magnetically separated, and the efficiency of the catalyst remains almost unaltered up to three cycles. PMID:19518151

Kantam, M Lakshmi; Yadav, Jagjit; Laha, Soumi; Srinivas, Pottabathula; Sreedhar, Bojja; Figueras, F

2009-06-19

415

Thermomagnetic determination of Fe3O4 magnetic nanoparticle diameters for biomedical applications  

Microsoft Academic Search

The utility and promise of magnetic nanoparticles (MagNPs) for biomedicine rely heavily on accurate determination of the particle diameter attributes. While the average functional size and size distribution of the magnetic nanoparticles directly impact the implementation and optimization of nanobiotechnology applications in which they are employed, the determination of these attributes using electron microscopy techniques can be time-consuming and misrepresentative

Brian D. Plouffe; Dattatri K. Nagesha; Robert S. Dipietro; Srinvas Sridhar; Don Heiman; Shashi K. Murthy; Lewis H. Lewis

2011-01-01

416

Thermomagnetic determination of Fe 3O 4 magnetic nanoparticle diameters for biomedical applications  

Microsoft Academic Search

The utility and promise of magnetic nanoparticles (MagNPs) for biomedicine rely heavily on accurate determination of the particle diameter attributes. While the average functional size and size distribution of the magnetic nanoparticles directly impact the implementation and optimization of nanobiotechnology applications in which they are employed, the determination of these attributes using electron microscopy techniques can be time-consuming and misrepresentative

Brian D. Plouffe; Dattatri K. Nagesha; Robert S. DiPietro; Srinvas Sridhar; Don Heiman; Shashi K. Murthy; Lewis H. Lewis

2011-01-01

417

Magnetorelaxometry—a new binding specific detection method based on magnetic nanoparticles  

Microsoft Academic Search

The measurement of the relaxing magnetisation of magnetic nanoparticles after switching off a magnetising field (magnetorelaxometry) was investigated towards its applicability for the determination of the binding of antibodies to their antigens. For this purpose a direct solid phase immunoassay using magnetic nanoparticles conjugated with an antibody against human IgG and a sandwich solid phase immunoassay using the identical biotinylated

J. Lange; R. Kötitz; A. Haller; L. Trahms; W. Semmler; W. Weitschies

2002-01-01

418

Magnetic field enhanced cell uptake efficiency of magnetic silica mesoporous nanoparticles  

NASA Astrophysics Data System (ADS)

The advantages of using magnetic mesoporous silica nanoparticles (M-MSNs) in biomedical applications have been widely recognized. However, poor uptake efficiency may hinder the potential of M-MSNs in many applications, such as cell tracking, drug delivery, fluorescence and magnetic resonance imaging. An external magnetic field may improve the cellular uptake efficiency. In this paper, we evaluated the effect of a magnetic field on the uptake of M-MSNs. We found that the internalization of M-MSNs by A549 cancer cells could be accelerated and enhanced by a magnetic field. An endocytosis study indicated that M-MSNs were internalized by A549 cells mainly through an energy-dependent pathway, namely clathrin-induced endocytosis. Transmission electron microscopy showed that M-MSNs were trafficked into lysosomes. With the help of a magnetic field, anticancer drug-loaded M-MSNs induced elevated cancer cell growth inhibition.

Liu, Qian; Zhang, Jixi; Xia, Weiliang; Gu, Hongchen

2012-05-01

419

Magnetic field synthesis of Fe3O4 nanoparticles used as a precursor of ferrofluids  

NASA Astrophysics Data System (ADS)

Methods to synthesize magnetic Fe3O4 nanoparticles and to modify the nanoparticle surface are presented in this paper. In these methods, Fe3O4 nanoparticles were prepared by co-precipitation, and the aging of nanoparticles was improved by applied magnetic field. The obtained nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and vibrating sample magnetometer (VSM). Thereafter, to enhance the compatibility between nanoparticles and water, an effective surface modification method was developed by grafting acrylic acid onto the nanoparticle surface. FT-IR, XRD, transmission electron microscopy (TEM), and thermogravimetry (TG) were used to characterize the resultant sample. The testing results indicated that the polyacrylic acid chains have been covalently bonded to the surface of magnetic Fe3O4 nanoparticles. The effects of initiator dosage, monomer concentration, and reaction temperature on the characteristics of surface-modified Fe3O4 nanoparticles were investigated. Moreover, the Fe3O4-g-PAA hybrid nanoparticles were dispersed in water to form ferrofluids (FFs). The obtained FFs were characterized by UV vis spectrophotometer, Gouy magnetic balance and laser particle-size analyzer. The testing results showed that the high-concentration FF had excellent stability, with high susceptibility and high saturation magnetization. The rheological properties of the FFs were also investigated using a rotating rheometer.

Hong, R. Y.; Pan, T. T.; Han, Y. P.; Li, H. Z.; Ding, J.; Han, Sijin

2007-03-01

420

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

PubMed Central

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

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

2010-01-01

421

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

422