Sample records for antibody-coated magnetic nanoparticles

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

    PubMed

    Schmerberg, Claire M; Li, Lingjun

    2013-01-15

    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

  2. Magnetic nanoparticles

    Microsoft Academic Search

    R. H Kodama

    1999-01-01

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

  3. Magnetic Nanoparticle Sensors

    PubMed Central

    Koh, Isaac; Josephson, Lee

    2009-01-01

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

  4. Theranostic magnetic nanoparticles.

    PubMed

    Yoo, Dongwon; Lee, Jae-Hyun; Shin, Tae-Hyun; Cheon, Jinwoo

    2011-10-18

    Early detection and treatment of disease is the most important component of a favorable prognosis. Biomedical researchers have thus invested tremendous effort in improving imaging techniques and treatment methods. Over the past decade, concepts and tools derived from nanotechnology have been applied to overcome the problems of conventional techniques for advanced diagnosis and therapy. In particular, advances in nanoparticle technology have created new paradigms for theranostics, which is defined as the combination of therapeutic and diagnostic agents within a single platform. In this Account, we examine the potential advantages and opportunities afforded by magnetic nanoparticles as platform materials for theranostics. We begin with a brief overview of relevant magnetic parameters, such as saturation magnetization, coercivity, and magnetocrystalline anisotropy. Understanding the interplay of these parameters is critical for optimizing magnetic characteristics needed for effective imaging and therapeutics, which include magnetic resonance imaging (MRI) relaxivity, heat emission, and attractive forces. We then discuss approaches to constructing an MRI nanoparticle contrast agent with high sensitivity. We further introduce a new design concept for a fault-free contrast agent, which is a T1 and T2 dual mode hybrid. Important capabilities of magnetic nanoparticles are the external controllability of magnetic heat generation and magnetic attractive forces for the transportation and movement of biological objects. We show that these functions can be utilized not only for therapeutic hyperthermia of cancer but also for controlled release of cancer drugs through the application of an external magnetic field. Additionally, the use of magnetic nanoparticles to drive mechanical forces is demonstrated to be useful for molecular-level cell signaling and for controlling the ultimate fate of the cell. Finally, we show that targeted imaging and therapy are made possible by attaching a variety of imaging and therapeutic components. These added components include therapeutic genes (small interfering RNA, or siRNA), cancer-specific ligands, and optical reporting dyes. The wide range of accessible features of magnetic nanoparticles underscores their potential as the most promising platform material available for theranostics. PMID:21823593

  5. DNA templated magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Kinsella, Joseph M.

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

  6. The significance of antibody coated bacteria in neuropathic bladder urines

    Microsoft Academic Search

    Rosemary Lindan

    1981-01-01

    A total of 234 patients with neuropathic bladder dysfunction and bacteria in the urine have been studied for the presence of antibody coating on the bacteria. Approximately one third of the patients so studied were found to have antibody coated bacteria in the urine (ACB + ) by fluorescent microscopy. No correlation could be found between evidence of active tissue

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

    PubMed

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

    2012-04-24

    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

  8. Facile Surface Functionalization of Hydrophobic Magnetic Nanoparticles

    E-print Network

    Tan, Weihong

    Facile Surface Functionalization of Hydrophobic Magnetic Nanoparticles Yuan Liu,,§ Tao Chen hydrophobic magnetic nanoparticles (MNPs) to an aqueous phase using tetrahydrofuran, NaOH and 3 to other types of hydrophobic nanoparticles to facilitate biomedical appli- cations of nanomaterials

  9. Spherical magnetic nanoparticles: magnetic structure and interparticle interaction

    E-print Network

    Paris-Sud XI, Université de

    made of soft magnetic material (permalloy as an example) when they reach the vortex regime. We considerSpherical magnetic nanoparticles: magnetic structure and interparticle interaction V. Russier The interaction between spherical magnetic nanoparticles is investigated from micromagnetic simulations

  10. TUTORIAL Open Access Cell labeling with magnetic nanoparticles

    E-print Network

    Paris-Sud XI, Université de

    TUTORIAL Open Access Cell labeling with magnetic nanoparticles: Opportunity for magnetic cell nanoparticles. This method may provide basically all kinds of cells with sufficient magnetization to allow cell) cellular MRI, magnetic nanoparticles, magnetic cell labeling, magnetic vectorization Rationale Magnetic

  11. Magnetic nanoparticle motion in external magnetic field

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    A set of equations describing the motion of a free magnetic nanoparticle in an external magnetic field in a vacuum, or in a medium with negligibly small friction forces is postulated. The conservation of the total particle momentum, i.e. the sum of the mechanical and the total spin momentum of the nanoparticle is taken into account explicitly. It is shown that for the motion of a nanoparticle in uniform magnetic field there are three different modes of precession of the unit magnetization vector and the director that is parallel the particle easy anisotropy axis. These modes differ significantly in the precession frequency. For the high-frequency mode the director points approximately along the external magnetic field, whereas the frequency and the characteristic relaxation time of the precession of the unit magnetization vector are close to the corresponding values for conventional ferromagnetic resonance. On the other hand, for the low-frequency modes the unit magnetization vector and the director are nearly parallel and rotate in unison around the external magnetic field. The characteristic relaxation time for the low-frequency modes is remarkably long. This means that in a rare assembly of magnetic nanoparticles there is a possibility of additional resonant absorption of the energy of alternating magnetic field at a frequency that is much smaller compared to conventional ferromagnetic resonance frequency. The scattering of a beam of magnetic nanoparticles in a vacuum in a non-uniform external magnetic field is also considered taking into account the precession of the unit magnetization vector and director.

  12. Chemical synthesis of magnetic nanoparticles.

    PubMed

    Hyeon, Taeghwan

    2003-04-21

    Recent advances in the synthesis of various magnetic nanoparticles using colloidal chemical approaches are reviewed. Typically, these approaches involve either rapid injection of reagents into hot surfactant solution followed by aging at high temperature, or the mixing of reagents at a low temperature and slow heating under controlled conditions. Spherical cobalt nanoparticles with various crystal structures have been synthesized by thermally decomposing dicobalt octacarbonyl or by reducing cobalt salts. Nanoparticles of Fe-Pt and other related iron or cobalt containing alloys have been made by simultaneously reacting their constituent precursors. Many different ferrite nanoparticles have been synthesized by the thermal decomposition of organometallic precursors followed by oxidation or by low-temperature reactions inside reverse micelles. Rod-shaped iron nanoparticles have been synthesized from the oriented growth of spherical nanoparticles, and cobalt nanodisks were synthesized from the thermal decomposition of dicobalt octacarbonyl in the presence of a mixture of two surfactants. PMID:12744306

  13. Enzymatic Synthesis of Magnetic Nanoparticles

    PubMed Central

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

    2015-01-01

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

  14. Fluorescent Magnetic Nanoparticles for Biomedical Applications

    E-print Network

    Candea, George

    Fluorescent Magnetic Nanoparticles for Biomedical Applications V.M.Dao, Dr. G. Coullerez, Dr. L, the main goal was to synthesize and to characterize novel fluorescent magnetic nanoparticles. These nanoparticles (NPs) involve superparamagnetic iron oxide nanoparticles (SPIONs), a fluorescently-labeled polymer

  15. Functional Magnetic Nanoparticles

    Microsoft Academic Search

    James Gass

    2012-01-01

    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

  16. Modulatable magnetically mediated thermoacoustic imaging with magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Feng, Xiaohua; Gao, Fei; Zheng, Yuanjin

    2015-04-01

    Modulatable magnetically mediated thermoacoustic imaging with magnetic nanoparticles is reported here. Under a pulsed radio frequency magnetic field, magnetic nanoparticles absorb energy strongly from the field and then emanate ultrasound signal thermoelastically. The energy absorption and, consequently, generated thermoacoustic signal strength depend sensitively on the magnetization state of magnetic nanoparticles, which can therefore be modulated effectively by a "bias" magnetic field. The magnetic modulation is demonstrated with a static magnet and modulated phantom imaging results are presented. This method offers an alternative modality for mapping magnetic nanoparticles and its unique modulation capability is demonstrated to be useful for contrast enhancement.

  17. SolidPhase Radioimmunoassay in Antibody-Coated Tubes

    Microsoft Academic Search

    Kevin Catt; Geoffrey W. Tregear

    1967-01-01

    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.

  18. Magnetic nanoparticle sensing: decoupling the magnetization from the excitation field

    PubMed Central

    Reeves, Daniel B.; Weaver, John B.

    2014-01-01

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

  19. Study of magnetocrystalline anisotropy of some magnetic nanoparticles

    Microsoft Academic Search

    Chandra Thapa

    2006-01-01

    Magnetic nanoparticles have applications to a variety devices ranging from high density magnetic data storage to targeted drug delivery. The suitability of specific magnetic nanoparticles for a particular application is mainly determined by their magnetic anisotropy energy. Magnetic nanoparticles with large magnetic anisotropy energy are particularly useful for high density data storage while the magnetic nanoparticles with small magnetic anisotropy

  20. Intravenous magnetic nanoparticle cancer hyperthermia

    PubMed Central

    Huang, Hui S; Hainfeld, James F

    2013-01-01

    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

  1. Surface Functionalization of Monodisperse Magnetic Nanoparticles

    E-print Network

    Lattuada, Marco

    We present a systematic methodology to functionalize magnetic nanoparticles through surface-initiated atom-transfer radical polymerization (ATRP). The magnetite nanoparticles are prepared according to the method proposed ...

  2. New magnetic nanoparticles for biotechnology.

    PubMed

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

    2004-08-26

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

  3. Magnetic properties of biosynthesized magnetite nanoparticles

    Microsoft Academic Search

    Lucas W. Yeary; Ji-Won Moon; L. J. Love; J. R. Thompson; C. J. Rawn; T. J. Phelps

    2005-01-01

    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

  4. Magnetic relaxation in dipolar magnetic nanoparticle clusters

    NASA Astrophysics Data System (ADS)

    Hovorka, Ondrej; Barker, Joe; Chantrell, Roy; Friedman, Gary; York-Drexel Collaboration

    2013-03-01

    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. 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. OH gratefully acknowledges support from a Marie Curie Intra European Fellowship within the 7th European Community Framework Programme under grant agreement PIEF-GA-2010-273014

  5. Magnetically multiplexed heating of single domain nanoparticles

    E-print Network

    Romero, G.

    Selective hysteretic heating of multiple collocated types of single domain magnetic nanoparticles (SDMNPs) by alternating magnetic fields (AMFs) may offer a useful tool for biomedical applications. The possibility of ...

  6. Biomedical Applications of Magnetic Nanoparticles and Fluids

    Microsoft Academic Search

    Diandra Leslie-Pelecky

    2006-01-01

    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

  7. Dual immobilization and magnetic manipulation of magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

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

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

  8. Platinum dendritic nanoparticles with magnetic behavior

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  9. Platinum dendritic nanoparticles with magnetic behavior

    SciTech Connect

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

    2014-07-21

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

  10. Immobilization of proteins on magnetic nanoparticles

    Microsoft Academic Search

    Tzu-Hsien Wang; Wen-Chien Lee

    2003-01-01

    Magnetic nanoparticles prepared from an alkaline solution of divalent and trivalent iron ions could covalently bind protein\\u000a via the activation ofN-ethyl-N-(3-dimethylaminopropyl) carbodiimide (EDC). Trypsin and avidin were taken as the model proteins for the formation of protein-nanoparticle\\u000a conjugates. The immobilized yield of protein increased with molar ratio of EDC\\/nanoparticle. Higher concentrations of added\\u000a protein could yield higher immobilized protein densities

  11. Bioavailability of magnetic nanoparticles to the brain

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

  12. Magnetic-Plasmonic Core-Shell Nanoparticles

    PubMed Central

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

    2013-01-01

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

  13. Bifunctional bacterial magnetic nanoparticles for tumor targeting

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

    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.

  14. Alignment of Magnetic Nanoparticles in Polymer Films

    NASA Astrophysics Data System (ADS)

    Yarar, Ecem; Rende, Deniz; Bucak, Seyda

    2013-03-01

    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.

  15. Application of Magnetic Nanoparticles to Gene Delivery

    PubMed Central

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

    2011-01-01

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

  16. Thermal potentiation of chemotherapy by magnetic nanoparticles

    PubMed Central

    Torres-Lugo, Madeline; Rinaldi, Carlos

    2014-01-01

    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

  17. Polyethylene magnetic nanoparticle: a new magnetic material for biomedical applications

    NASA Astrophysics Data System (ADS)

    Chatterjee, Jhunu; Haik, Yousef; Chen, Ching-Jen

    2002-05-01

    Polyethylene magnetic nanoparticles were synthesized by nonsolvent and temperature induced crystallization along with ultrasonication. Low molecular weight polyethylene wax and maghemite were used for forming the composite particles. These particles were further coated with avidin. The nanoparticles are characterized using STEM, AFM and SQUID. Nanomagnetic particles were found to have two distinct morphologies and have superparamagnetic properties.

  18. MAGNETIC NANOPARTICLE HYPERTHERMIA IN CANCER TREATMENT

    PubMed Central

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

    2013-01-01

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

  19. Estimation of particle magnetic moment distribution for antiferromagnetic ferrihydrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Rani, Chandni; Tiwari, S. D.

    2015-07-01

    Magnetization as a function of applied magnetic field at different temperatures for antiferromagnetic nanoparticles of ferrihydrite is measured and analyzed considering a distribution in particle magnetic moment. We find that the magnetization of this nanoparticle system is affected by the presence of particle magnetic moment distribution. This particle magnetic moment distribution is estimated at different temperatures.

  20. Effect of Magnetic Nanoparticle Additive on Characteristics of Magnetorheological Fluid

    Microsoft Academic Search

    Kang Hyun Song; Bong Jun Park; Hyoung Jin Choi

    2009-01-01

    Magnetorheological (MR) fluids, suspension of magnetic pure carbonyl iron (CI) in non magnetic carrier, were prepared with and without magnetic CI nanoparticle additive in this study. Initially, the magnetic CI nanoparticle additive was synthesized in a rather simple process of decomposition of penta carbonyl iron (Fe(CO)5) using oleyl amine and kerosene. Magnetic property and morphology of the synthesized magnetic CI

  1. Targeting intracellular compartments by magnetic polymeric nanoparticles.

    PubMed

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

    2013-09-27

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

  2. 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...

  3. Measurement of magnetic nanoparticle relaxation time

    PubMed Central

    Weaver, John B.; Kuehlert, Esra

    2012-01-01

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

  4. Dispersion of magnetic nanoparticles in polymer films

    NASA Astrophysics Data System (ADS)

    Gass, J.

    2005-03-01

    Magnetic nanoparticles embedded in polymer matrices have excellent potential for EMI shielding and biomedical applications. However, uniform dispersion of particles in polymers without agglomeration is quite challenging. We have fabricated PMMA/polypyrrole bilayer structures embedded with Fe3O4 magnetic nanoparticles (mean size ˜ 12 nm) synthesized using wet chemical methods. The magnetic polymer nanocomposites were spin-coated on various substrates. Agglomeration-free dispersion of nanoparticles was achieved by coating the particles with surfactants and by dissolving both the particles and PMMA in cholorobenzene. Structural characterization was done using XRD and TEM. Magnetic properties of the bilayer structures indicated that the superparamagnetic and ferromagnetic response of the polymer nanocomposites including parameters such as the coercivity, remanence and saturation magnetization could be systematically varied with controlled amounts of nanoparticle dispersions in the polymer media. The RF impedance up to frequencies of 3 GHz measured using a vector network analyzer will also be presented. Overall, we demonstrate that magnetic polymer nanocomposite films are excellent candidates for EMI suppression applications. Work supported by NSF through Grant No. ECS 0140047

  5. Tuning the Magnetic Properties of Nanoparticles

    PubMed Central

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

    2013-01-01

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

  6. Polymer nanocomposites with embedded magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Poddar, P.; Wilson, J. L.; Srikanth, H.; Mohomed, K.; Harmon, J. P.

    2004-03-01

    Magnetic nanoparticles embedded in polymer matrices have excellent potential for applications such as EMI shielding. We have synthesized magnetic polymer nanocomposites based on polystyrene, PMMA, polypyrrole using various methods like melt blending, ultrasonic and photo polymerization. The resulting composites were processed as spin-coated thin films and in bulk form. The processing conditions were optimized to achieve good uniform dispersion of the nanoparticles (Fe, Fe_2O_3) in the polymer matrices. Microstructural characterization by SEM revealed that the particles tend to migrate below the surface. Clustering of nanoparticles in varying size ranges was also observed. Magnetic measurements showed that controlled variation of the ferromagnetic response can be obtained by varying the volumetric composition of nanoparticles. Hysteresis loops even for Fe-based systems exhibited a large coercivity presumably associated with surface oxidation and/or clustering of nanoparticles. Overall, the excellent dispersion coupled with reasonable control over magnetic properties achieved in our experiments is promising for electromagnetic applications of these materials. Work supported by NSF through grant No. ECS-0140047

  7. Microfluidic Biosensing Systems Using Magnetic Nanoparticles

    PubMed Central

    Giouroudi, Ioanna; Keplinger, Franz

    2013-01-01

    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

  8. Simulations of magnetic nanoparticle Brownian motion

    E-print Network

    Daniel B Reeves; John B Weaver

    2014-03-25

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

  9. Functionalized magnetic nanoparticle analyte sensor

    DOEpatents

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

    2014-03-25

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

  10. Magnetic Nanoparticles for Cancer Diagnosis and Therapy

    PubMed Central

    Yigit, Mehmet V.; Moore, Anna

    2013-01-01

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

  11. Magnetic nanoparticles for application in cancer therapy

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    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.

  12. Characterization of magnetically fractionated magnetic nanoparticles for magnetic particle imaging

    NASA Astrophysics Data System (ADS)

    Yoshida, T.; Othman, N. B.; Enpuku, K.

    2013-11-01

    We have characterized fractionated magnetic nanoparticles (MNPs) for magnetic particle imaging. Original Ferucarbotran particles were magnetically divided into three fractionated MNPs called MS1, MS2, and MS3. Harmonic spectra from the three fractionated MNPs were measured at excitation fields of 2.8 and 28 mT with a frequency of 10 kHz. MS1 showed a 2.5-fold increase in the harmonic spectrum over that of the original MNPs. To understand the origin of the enhancement in the harmonic spectrum from MS1, we explored the magnetic properties of the MS series, such as distributions of effective core size and anisotropy energy barrier, and the correlation between them. Using these results, we performed numerical simulations of the harmonic spectra based on the Langevin equation. The simulation results quantitatively explained the experimental results of the fractionated MS series. It was also clarified that MS1 includes a large portion of the MNPs that are responsible for the harmonic spectrum.

  13. Multifunctional magnetic nanoparticles for magnetic resonance imaging and cancer therapy

    Microsoft Academic Search

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

    2011-01-01

    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

  14. Static magnetic properties of Maghemite nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  15. Biomedical and environmental applications of magnetic nanoparticles

    Microsoft Academic Search

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

    2010-01-01

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

  16. EDITORIAL: Biomedical applications of magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    O'Grady, K.

    2002-07-01

    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

  17. Productive encounter: molecularly imprinted nanoparticles prepared using magnetic templates.

    PubMed

    Berghaus, Melanie; Mohammadi, Reza; Sellergren, Börje

    2014-08-18

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

  18. The preparation of magnetic nanoparticles for applications in biomedicine

    Microsoft Academic Search

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

    2003-01-01

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

  19. Spectral-domain magnetomotive OCT imaging of magnetic nanoparticle biodistribution

    E-print Network

    Oldenburg, Amy

    Spectral-domain magnetomotive OCT imaging of magnetic nanoparticle biodistribution Amy L coherence tomography (MMOCT) is a method for imaging the distribution of magnetic nanoparticles in tissue, with a demonstrated sensitivity to nanoparticles and imaging time of 5 s. Agarose phantoms

  20. Application of iron magnetic nanoparticles in protein immobilization.

    PubMed

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

    2014-01-01

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

  1. Nonlinear simulations to optimize magnetic nanoparticle hyperthermia

    SciTech Connect

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

    2014-03-10

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

  2. Magnetic nanoparticles for magnetoresistance-based biodetection.

    PubMed

    Sun, Xiaolian; Ho, Don; Lacroix, Lise-Marie; Xiao, John Q; Sun, Shouheng

    2012-03-01

    Magnetic nanoparticles (MNPs) have been studied widely as a powerful diagnostic probe and therapeutic agent for biomedical applications. In recent years, they are also found to be sensitive to magnetoresistive (MR) devices and MNP-MR biochips are predicted to be more affordable, portable and sensitive than the conventional optical detection methods. In this MNP-MR biochip design, MNP probes are required to have high magnetic moment, high susceptibility, and be target-specific. This review summarizes recent advances in chemical syntheses and functionalization of MNPs with controlled magnetic properties for sensitive MR detection and for bio-sensing applications. PMID:22157074

  3. Two-Dimensional Manipulation of Magnetic Nanoparticles in Microfluidic Systems

    NASA Astrophysics Data System (ADS)

    Cao, Quanliang; Han, Xiaotao; Li, Liang

    2013-02-01

    A magnetic manipulation technique based on a superimposed gradient magnetic field source for controlling magnetic nanoparticles in microfluidic channels was proposed. The designed magnetic field is composed of one gradient magnetic field generated by micro-electromagnetic coils positioned near a microfluidic channel and one external uniform magnetic field generated by large Helmholtz coil pairs. By controlling the configuration of Helmholtz coils, magnetic nanoparticles can be transported in different movement modes. As a proof of concept, the transport behavior of magnetic nanoparticles under different configurations of Helmholtz coils was successfully performed in two-dimensional (2D) geometries.

  4. Magnetic properties of metallic ferromagnetic nanoparticle composites

    NASA Astrophysics Data System (ADS)

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

    2004-07-01

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

  5. Electrochemical fabrication of nanocomposite films containing magnetic metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Hayashi, Yoshiaki; Hashi, Shuichiro; Kura, Hiroaki; Yanai, Takeshi; Ogawa, Tomoyuki; Ishiyama, Kazushi; Nakano, Masaki; Fukunaga, Hirotoshi

    2015-07-01

    Controlling the structure composed of soft and hard magnetic phases at the nanoscale is the key to fabricating nanocomposite magnets with efficient exchange coupling. In our previous study, nanocomposite films containing ferrite nanoparticles were fabricated by a combination of electrophoretic deposition and electroplating to show one possibility of controlling the structure of nanocomposite magnets three-dimensionally by applying self-assembly of magnetic nanoparticles. To expand this combination method to the fabrication of nanocomposite magnets, the use of magnetic metal nanoparticles is desired. In this paper, we attempted to fabricate nanocomposite films composed of Fe–Co nanoparticles in a Fe–Pt matrix by this combination method. Through cross-sectional observation and XRD analysis, a nanostructure composed of Fe–Co nanoparticles embedded in a L10 Fe–Pt matrix was confirmed. These results indicate that this method is capable of producing composite materials containing metal magnetic nanoparticles.

  6. High-magnetic-moment multifunctional nanoparticles for nanomedicine applications

    Microsoft Academic Search

    Yun Hao Xu; Jianmin Bai; Jian-Ping Wang

    2007-01-01

    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,

  7. Poly(allylamine) Stabilized Iron Oxide Magnetic Nanoparticles

    Microsoft Academic Search

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

    2007-01-01

    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

  8. Photoconjugation of molecularly imprinted polymer with magnetic nanoparticles

    PubMed Central

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

    2013-01-01

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

  9. Water-soluble magnetic nanoparticles with biologically active stabilizers

    Microsoft Academic Search

    Alla Zablotskaya; Izolda Segal; Edmunds Lukevics; Mikhail Maiorov; Dmitry Zablotsky; Elmars Blums; Irina Shestakova; Ilona Domracheva

    2009-01-01

    We present the results of the interaction of iron oxide nanoparticles with some biologically active surfactants, namely, oleic acid and cytotoxic alkanolamine derivatives. Physico-chemical properties, as magnetization, magnetite concentration and particle diameter, of the prepared magnetic samples were studied. The nanoparticle size of 11nm for toluene magnetic fluid determined by TEM is in good agreement with the data obtained by

  10. Pulsed Laser Synthesized Magnetic Cobalt Oxide Nanoparticles for Biomedical Applications

    Microsoft Academic Search

    Hari Bhatta; Ram Gupta; Kartik Ghosh; Pawan Kahol; Robert Delong; Adam Wanekawa

    2011-01-01

    Nanomaterials research has become a major attraction in the field of advanced materials research in the area of Physics, Chemistry, and Materials Science. Biocompatible and chemically stable magnetic metal oxide nanoparticles have biomedical applications that includes drug delivery, cell and DNA separation, gene cloning, magnetic resonance imaging (MRI). This research is aimed at the fabrication of magnetic cobalt oxide nanoparticles

  11. Magnetically driven plasmid DNA delivery with biodegradable polymeric nanoparticles

    Microsoft Academic Search

    Michael Chorny; Boris Polyak; Ivan S. Alferiev; Kenneth Walsh; Gary Friedman; Robert J. Levy

    2007-01-01

    Targeting gene therapy remains a chal- lenge. The use of magnetic force to achieve this was investigated in the present study. It was hypothesized that nanoparticles with both controllable particle size and magnetic properties would enable magnetically driven gene delivery. We investigated this hypothesis by creating a family of novel biodegradable poly- meric superparamagnetic nanoparticle (MNP) for- mulations. Polylactide MNP

  12. Magnetic order of Fe3O4 Nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  13. Magnetic vectoring of magnetically responsive nanoparticles within the murine peritoneum

    NASA Astrophysics Data System (ADS)

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

    2007-04-01

    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.

  14. Iron Oxide Nanoparticles for Magnetically-Guided and Magnetically-Responsive Drug Delivery

    PubMed Central

    Estelrich, Joan; Escribano, Elvira; Queralt, Josep; Busquets, Maria Antònia

    2015-01-01

    In this review, we discuss the recent advances in and problems with the use of magnetically-guided and magnetically-responsive nanoparticles in drug delivery and magnetofection. In magnetically-guided nanoparticles, a constant external magnetic field is used to transport magnetic nanoparticles loaded with drugs to a specific site within the body or to increase the transfection capacity. Magnetofection is the delivery of nucleic acids under the influence of a magnetic field acting on nucleic acid vectors that are associated with magnetic nanoparticles. In magnetically-responsive nanoparticles, magnetic nanoparticles are encapsulated or embedded in a larger colloidal structure that carries a drug. In this last case, an alternating magnetic field can modify the structure of the colloid, thereby providing spatial and temporal control over drug release. PMID:25867479

  15. Magnetic nanoparticles and magnetocrystalline anisotropy

    Microsoft Academic Search

    S. A. Majetich; J. H. Scott; E. M. Kirkpatrick; K. Chowdary; K. Gallagher; M. E. McHenry

    1997-01-01

    The size dependent properties of monodomain ferromagnets are described. Following an introduction to the technical magnetics parameters used to describe bulk ferromagnets, the size dependence of these parameters is described. Bulk ferromagnetic materials are generally described as either hard or soft, depending on the value of their magnetocrystalline anisotropy. The role of anisotropy in monodomain ferromagnets is investigated through examination

  16. Surface modification of magnetic metal nanoparticles through irradiation graft polymerization

    Microsoft Academic Search

    Min Zhi Rong; Ming Qiu Zhang; Hong Bing Wang; Han Min Zeng

    2002-01-01

    To tailor the interfacial interaction in magnetic metal nanoparticles filled polymer composites, the surfaces of iron, cobalt and nickel nanoparticles were grafted by irradiation polymerization. In the current report, effects of grafting conditions, including irradiation atmosphere, irradiation dose and monomer concentration, on the grafting reaction are presented. The interaction between the nanoparticles and the grafted polymer was studied by thermal

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

    E-print Network

    Paris-Sud XI, Université de

    LYSIS OF ANTIBODY COATED CHICKEN ERYTHROCYTES BY A NON-LYMPHOCYTE PIG BLOOD LEUKOCYTE B. CHARLEY H : erythrocyte-antibody. Koren et al., 1978 ; Wardley et al., 1976). Dif- ferent cell types, all of which bearing communication, using a con- ventionnal slchromium release test with label- led chicken erythrocytes sensitized

  18. Neutron diffraction and magnetism of CoO antiferromagnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Silva, N. J. O.; Puente-Orench, I.; Martins, M.; Trindade, T.; Millán, A.; Campo, J.; Palacio, F.

    2011-10-01

    We report a study on neutron diffraction and magnetic properties ol cobalt oxide CoO antiferromagnetic nanoparticles with different sizes. The nanoparticles are composed by a structurally and magnetically ordered core and a structurally ordered and magnetically disordered shell with a thickness of about 2 nm. The ordered core has cell parameters, moments direction and modulus similar to those of bulk CoO. Small differences found are attributed to an increase of the oxidation of the nanoparticles with the decrease of size. A remanent moment Mr can be induced in CoO nanoparticles by crossing the transition temperature in the presence of a magnetic field, while the magnetic structure of the antiferromagnetically ordered moments of the nanoparticles core remains unchanged after field cooling within the experimental precision, suggesting that Mr arises in the magnetically disordered shell.

  19. Inverted Linear Halbach Array for Separation of Magnetic Nanoparticles

    PubMed Central

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

    2014-01-01

    A linear array of Nd-Fe-B magnets has been designed and constructed in an inverted Halbach configuration for use in separating magnetic nanoparticles. The array provides a large region of relatively low magnetic field, yet high magnetic field gradient in agreement with finite element modeling calculations. The magnet assembly has been combined with a flow channel for magnetic nanoparticle suspensions, such that for an appropriate distance away from the assembly, nanoparticles of higher moment aggregate and accumulate against the channel wall, with lower moment nanoparticles flowing unaffected. The device is demonstrated for iron oxide nanoparticles with diameters of ~ 5 and 20 nm. In comparison to other approaches, the inverted Halbach array is more amenable to modeling and to scaling up to preparative quantities of particles. PMID:25382864

  20. Preparation of magnetic chitosan nanoparticles and immobilization of laccase

    Microsoft Academic Search

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

    2009-01-01

    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

  1. Transformation kinetics & magnetism of magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Laurenzi, Mark Anthony, III

    This dissertation presents the results of a study of the nucleation and growth kinetics and magnetic properties of iron-oxide based nanoparticles that are formed by crystallization of a Na-Ca borate amorphous precursor. In addition to the interesting phase transformation kinetics and concentration dependent growth phenomena observed in this system, it also provides an opportunity to study finite-size effects on the magnetic properties of single domain particles. The crystallization of iron oxide nanoparticles and the phase identity (magnetite or maghemite) upon heat treatment was investigated over a range of time, temperature, and redox conditions. X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron diffraction (ED) were used to structurally characterize the resulting nanoparticles. Magnetite formation was favored under more reducing conditions whereas maghemite was formed under more oxidizing conditions. Under all conditions investigated, the particle size fell in the narrow range of about 2.5 to 4.5 nm and showed no evidence of further growth with time. This is believed to result from the increased viscosity in the iron-depleted diffusion field surrounding each particle. The magnetic properties were characterized using a superconducting quantum interference device (SQUID) and Mossbauer spectrometer (MS). Magnetization measurements were made from room temperature down to ˜10 K under field-cooled (FC) and zero-field-cooled (ZFC) conditions. The average blocking temperature obtained from these measurements is generally consistent with the measured particle size for reasonable values of the anisotropy constant. Unlike maghemite, bulk magnetite exhibits a metal-insulator transition, first reported by Verwey in 1939. The effect was attributed by Verwey and others to a charge-ordering transition. However, very recent data suggest that the Verwey transition is instead associated with a structural transition from inverse to normal spinel. In the present work, the magnetization data for samples produced under more reducing conditions show clear evidence of a Verwey transition in 4--4.5 nm magnetite nanoparticles. However, the transition is found to be shifted from the bulk value of ˜120 K to 85--95 K, which is attributed to finite-size effects.

  2. Millimeter Scale Alignment of Magnetic Nanoparticle Functionalized Microtubules in Magnetic Fields

    E-print Network

    Hancock, William O.

    Millimeter Scale Alignment of Magnetic Nanoparticle Functionalized Microtubules in Magnetic Fields techniques,4 by viscous forces,5 or by strong magnetic or electric fields applied during tubule ferrite nanoparticles (CoFe2O4) and the facile use of an externally applied magnetic field to control

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

    PubMed Central

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

    2013-01-01

    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

  4. MRI contrast enhancement using Magnetic Carbon Nanoparticles

    NASA Astrophysics Data System (ADS)

    Chaudhary, Rakesh P.; Kangasniemi, Kim; Takahashi, Masaya; Mohanty, Samarendra K.; Koymen, Ali R.; Department of Physics, University of Texas at Arlington Team; University of Texas Southwestern Medical Center Team

    2014-03-01

    In recent years, nanotechnology has become one of the most exciting forefront fields in cancer diagnosis and therapeutics such as drug delivery, thermal therapy and detection of cancer. Here, we report development of core (Fe)-shell (carbon) nanoparticles with enhanced magnetic properties for contrast enhancement in MRI imaging. These new classes of magnetic carbon nanoparticles (MCNPs) are synthesized using a bottom-up approach in various organic solvents, using the electric plasma discharge generated in the cavitation field of an ultrasonic horn. Gradient echo MRI images of well-dispersed MCNP-solutions (in tube) were acquired. For T2 measurements, a multi echo spin echo sequence was performed. From the slope of the 1/T2 versus concentration plot, the R2 value for different CMCNP-samples was measured. Since MCNPs were found to be extremely non-reactive, and highly absorbing in NIR regime, development of carbon-based MRI contrast enhancement will allow its simultaneous use in biomedical applications. We aim to localize the MCNPs in targeted tissue regions by external DC magnetic field, followed by MRI imaging and subsequent photothermal therapy.

  5. Spectral-domain magnetomotive OCT imaging of magnetic nanoparticle biodistribution

    Microsoft Academic Search

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

    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

  6. TOPICAL REVIEW: Functionalisation of magnetic nanoparticles for applications in biomedicine

    Microsoft Academic Search

    Catherine C. Berry; Adam S. G. Curtis

    2003-01-01

    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

  7. Monodisperse magnetic nanoparticles for theranostic applications.

    PubMed

    Ho, Don; Sun, Xiaolian; Sun, Shouheng

    2011-10-18

    Effective medical care requires the concurrent monitoring of medical treatment. The combination of imaging and therapeutics allows a large degree of control over the treatment efficacy and is now commonly referred to as "theranostics". Magnetic nanoparticles (NPs) provide a unique nanoplatform for theranostic applications because of their biocompatibility, their responses to the external magnetic field, and their sizes which are comparable to that of functional biomolecules. Recent studies of magnetic NPs for both imaging and therapeutic applications have led to greater control over size, surface functionalization, magnetic properties, and specific binding capabilities of the NPs. The combination of the deep tissue penetration of the magnetic field and the ability of magnetic NPs to enhance magnetic resonance imaging sensitivity and magnetic heating efficiency makes magnetic NPs promising candidates for successful future theranostics. In this Account, we review recent advances in the synthesis of magnetic NPs for biomedical applications such as magnetic resonance imaging (MRI) and magnetic fluid hyperthermia (MFH). Our focus is on iron oxide (Fe(3)O(4)) NPs, gold-iron oxide (Au-Fe(3)O(4)) NPs, metallic iron (Fe) NPs, and Fe-based alloy NPs, such as iron-cobalt (FeCo) and iron-platinum (FePt) NPs. Because of the ease of fabrication and their approved clinical usage, Fe(3)O(4) NPs with controlled sizes and surface chemistry have been studied extensively for MRI and MFH applications. Porous hollow Fe(3)O(4) NPs are expected to have similar magnetic, chemical, and biological properties as the solid Fe(3)O(4) NPs, and their structures offer the additional opportunity to store and release drugs at a target. The Au-Fe(3)O(4) NPs combine both magnetically active Fe(3)O(4) and optically active Au within one nanostructure and are a promising NP platform for multimodal imaging and therapeutics. Metallic Fe and FeCo NPs offer the opportunity for probes with even higher magnetizations. However, metallic NPs are normally very reactive and are subject to fast oxidation in biological solutions. Once they are coated with a layer of polycrystalline Fe(3)O(4) or a graphitic shell, these metallic NPs are more stable and provide better contrast for MRI and more effective heating for MFH. FePt NPs are chemically more stable than Fe and FeCo NPs and have shown great potential as contrast agents for both MRI and X-ray computed tomography (CT) and as robust probes for controlled heating in MFH. PMID:21661754

  8. Biotin avidin amplified magnetic immunoassay for hepatitis B surface antigen detection using GoldMag nanoparticles

    NASA Astrophysics Data System (ADS)

    Yu, An; Geng, Tingting; Fu, Qiang; Chen, Chao; Cui, Yali

    2007-04-01

    Using GoldMag (Fe3O4/Au) nanoparticles as a carrier, a biotin-avidin amplified ELISA was developed to detect hepatitis B surface antigen (HBsAg). A specific antibody was labeled with biotin and then used to detect the antigen with an antibody coated on GoldMag nanoparticles by a sandwich ELISA assay. The results showed that 5 mol of biotin were surface bound per mole of antibody. The biotin-avidin amplified ELISA assay has a higher sensitivity than that of the direct ELISA assay. There is 5-fold difference between HBsAg positive and negative serum even at dilution of 1:10000, and the relative standard deviation of the parallel positive serum at dilution of 1:4000 is 5.98% (n=11).

  9. Polysaccharide-Coated Magnetic Nanoparticles for Imaging and Gene Therapy

    PubMed Central

    Uthaman, Saji; Cherukula, Kondareddy; Cho, Chong-Su; Park, In-Kyu

    2015-01-01

    Today, nanotechnology plays a vital role in biomedical applications, especially for the diagnosis and treatment of various diseases. Among the many different types of fabricated nanoparticles, magnetic metal oxide nanoparticles stand out as unique and useful tools for biomedical applications, because of their imaging characteristics and therapeutic properties such as drug and gene carriers. Polymer-coated magnetic particles are currently of particular interest to investigators in the fields of nanobiomedicine and fundamental biomaterials. Theranostic magnetic nanoparticles that are encapsulated or coated with polymers not only exhibit imaging properties in response to stimuli, but also can efficiently deliver various drugs and therapeutic genes. Even though a large number of polymer-coated magnetic nanoparticles have been fabricated over the last decade, most of these have only been used for imaging purposes. The focus of this review is on polysaccharide-coated magnetic nanoparticles used for imaging and gene delivery. PMID:26078971

  10. Quantitative Evaluation of the Total Magnetic Moments of Colloidal Magnetic Nanoparticles: A Kinetics-based Method.

    PubMed

    Liu, Haiyi; Sun, Jianfei; Wang, Haoyao; Wang, Peng; Song, Lina; Li, Yang; Chen, Bo; Zhang, Yu; Gu, Ning

    2015-06-01

    A kinetics-based method is proposed to quantitatively characterize the collective magnetization of colloidal magnetic nanoparticles. The method is based on the relationship between the magnetic force on a colloidal droplet and the movement of the droplet under a gradient magnetic field. Through computational analysis of the kinetic parameters, such as displacement, velocity, and acceleration, the magnetization of colloidal magnetic nanoparticles can be calculated. In our experiments, the values measured by using our method exhibited a better linear correlation with magnetothermal heating, than those obtained by using a vibrating sample magnetometer and magnetic balance. This finding indicates that this method may be more suitable to evaluate the collective magnetism of colloidal magnetic nanoparticles under low magnetic fields than the commonly used methods. Accurate evaluation of the magnetic properties of colloidal nanoparticles is of great importance for the standardization of magnetic nanomaterials and for their practical application in biomedicine. PMID:25943076

  11. Silicon Nanoparticles as Hyperpolarized Magnetic Resonance Imaging Agents

    PubMed Central

    Aptekar, Jacob W.; Cassidy, Maja C.; Johnson, Alexander C.; Barton, Robert A.; Lee, Menyoung; Ogier, Alexander C.; Vo, Chinh; Anahtar, Melis N.; Ren, Yin; Bhatia, Sangeeta N.; Ramanathan, Chandrasekhar; Cory, David G.; Hill, Alison L.; Mair, Ross W.; Rosen, Matthew S.; Walsworth, Ronald L.

    2014-01-01

    Magnetic resonance imaging of hyperpolarized nuclei provides high image contrast with little or no background signal. To date, in-vivo applications of pre-hyperpolarized materials have been limited by relatively short nuclear spin relaxation times. Here, we investigate silicon nanoparticles as a new type of hyperpolarized magnetic resonance imaging agent. Nuclear spin relaxation times for a variety of Si nanoparticles are found to be remarkably long, ranging from many minutes to hours at room temperature, allowing hyperpolarized nanoparticles to be transported, administered, and imaged on practical time scales. Additionally, we demonstrate that Si nanoparticles can be surface functionalized using techniques common to other biologically targeted nanoparticle systems. These results suggest that Si nanoparticles can be used as a targetable, hyperpolarized magnetic resonance imaging agent with a large range of potential applications. PMID:19950973

  12. Surface modification of magnetic nanoparticles in biomedicine

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

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

    PubMed

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

    2011-01-01

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

  14. TOPICAL REVIEW: Applications of magnetic nanoparticles in biomedicine

    Microsoft Academic Search

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

    2003-01-01

    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

  15. Local Control of Ultrafast Dynamics of Magnetic Nanoparticles

    SciTech Connect

    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

    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.

  16. A Renewable Electrochemical Magnetic Immunosensor Based on Gold Nanoparticle Labels

    SciTech Connect

    Liu, Guodong; Lin, Yuehe

    2005-05-24

    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.

  17. Optimal Halbach permanent magnet designs for maximally pulling and pushing nanoparticles

    E-print Network

    Shapiro, Benjamin

    Optimal Halbach permanent magnet designs for maximally pulling and pushing nanoparticles A. Sarwar Available online 19 September 2011 Keywords: Magnetic nanoparticle Targeted drug deliver Magnetic drug targeting Optimal permanent magnet Nano-particle trapping Pushing nanoparticle Halbach array design a b

  18. Magnetic nanoparticles for applications in oscillating magnetic field

    SciTech Connect

    Peeraphatdit, Chorthip

    2010-12-15

    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.

  19. Vinamax: a macrospin simulation tool for magnetic nanoparticles.

    PubMed

    Leliaert, Jonathan; Vansteenkiste, Arne; Coene, Annelies; Dupré, Luc; Van Waeyenberge, Bartel

    2015-04-01

    We present Vinamax, a simulation tool for nanoparticles that aims at simulating magnetization dynamics on very large timescales. To this end, each individual nanoparticle is approximated by a macrospin. Vinamax numerically solves the Landau-Lifshitz equation by adopting a dipole approximation method, while temperature effects can be taken into account with two stochastic methods. It describes the influence of demagnetizing and anisotropy fields on magnetic nanoparticles at finite temperatures in a space- and time-dependent externally applied field. Vinamax can be used in biomedical research where nanoparticle imaging techniques are under development, e.g., to validate other higher-level models and study their limitations. PMID:25552437

  20. The effects of magnetic nanoparticle properties on magnetic fluid hyperthermia

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

    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.

  1. Magnetic anisotropy determination and magnetic hyperthermia properties of small Fe nanoparticles in the superparamagnetic regime

    Microsoft Academic Search

    B. Mehdaoui; A. Meffre; L.-M. Lacroix; J. Carrey; S. Lachaize; M. Respaud; M. Gougeon; B. Chaudret

    2009-01-01

    We report on the magnetic and hyperthermia properties of iron nanoparticles\\u000asynthesized by organometallic chemistry. They are 5.5 nm in diameter and\\u000adisplay a saturation magnetization close to the bulk one. Magnetic properties\\u000aare dominated by the contribution of aggregates of nanoparticles with respect\\u000ato individual isolated nanoparticles. Alternative susceptibility measurements\\u000aare been performed on a low interacting system obtained

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  3. Magnetic Nanoparticles: Surface Effects and Properties Related to Biomedicine Applications

    PubMed Central

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

    2013-01-01

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

  4. Preparation of magnetic nanoparticles by pulsed plasma chemical vapor synthesis

    Microsoft Academic Search

    I. Matsui

    2006-01-01

    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

  5. Remanent magnetization in CoO antiferromagnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Silva, N. J. O.; Millán, A.; Palacio, F.; Martins, M.; Trindade, T.; Puente-Orench, I.; Campo, J.

    2010-09-01

    We report a study on the remanent magnetization Mr induced by field cooling across the ordering temperature TN in antiferromagnetic CoO nanoparticles with different sizes. The nanoparticles are composed by a structurally and magnetically ordered core and a structurally ordered and magnetically disordered shell with a thickness of about 2 nm. The ordered core has cell parameters, moments direction, and modulus similar to those of bulk CoO. Mr is shown to be proportional to the cooling field Hcool . The low-temperature saturation values of Mr [Mr(0)] in the CoO nanoparticles are about two orders of magnitude higher than those found for bulk CoO. Mr/Mr(0) of CoO nanoparticles scales with temperature in a single curve, independently on the magnitude of Hcool and on nanoparticles size, except for temperatures near to TN since TN is size dependent.

  6. Magnetic order in two-dimensional nanoparticle assemblies

    NASA Astrophysics Data System (ADS)

    Georgescu, M.

    2008-12-01

    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.

  7. The role of cobalt ferrite magnetic nanoparticles in medical science.

    PubMed

    Amiri, S; Shokrollahi, H

    2013-01-01

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

  8. Noninvasive assessment of magnetic nanoparticle-cancer cell interactions

    PubMed Central

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

    2012-01-01

    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. PMID:22945022

  9. Synthesis and characterization of magnetic nanoparticles and nano-composites

    Microsoft Academic Search

    Wai Lun Sin

    2008-01-01

    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

  10. Structural and magnetic domains characterization of magnetite nanoparticles

    Microsoft Academic Search

    J. Santoyo-Salazar; M. A. Castellanos-Roman; L. Beatriz Gómez

    2007-01-01

    Recently, important advances have been achieved in application, reproducibility and response ability of magnetic materials due to the relationships among processing, structure and nanometric size particle. Features like homogeneity of compounds and nanoparticle-sizing have improved some magnetic properties of materials and their field application. Of particular interest is the study of magnetic materials at the atomic and microstuctural level because

  11. Optimizing hysteretic power loss of magnetic ferrite nanoparticles

    E-print Network

    Chen, Ritchie

    2013-01-01

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

  12. Lectin-functionalized magnetic iron oxide nanoparticles for reproductive improvement

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Semen ejaculates contain heterogeneous sperm populations that can jeopardize male fertility. Recent development of nanotechnology in physiological systems may have applications in reproductive biology. Here, we used magnetic nanoparticles as a novel strategy for sperm purification to imp...

  13. Magnetic nanoparticle-supported glutathione: a conceptually sustainable organocatalyst

    EPA Science Inventory

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

  14. Temperature of the Magnetic Nanoparticle Microenvironment: Estimation from Relaxation Times

    PubMed Central

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

    2014-01-01

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

  15. Magnetic molecularly imprinted nanoparticles for recognition of lysozyme

    Microsoft Academic Search

    Tao Jing; Hairong Du; Qing Dai; Huan Xia; Jiwei Niu; Qiaolin Hao; Surong Mei; Yikai Zhou

    2010-01-01

    Molecular imprinting is an attractive technique for preparing mimics of natural, biological receptors. Nevertheless, the imprinting of macromolecule remains a challenge due to their bulkiness and sensitivity to denaturation. In this work, we presented a method for preparing multifunctional lysozyme-imprinted nanoparticles (magnetic susceptibility, molecular recognition and environmental response). The magnetic susceptibility was imparted through the successful encapsulation of Fe3O4 nanoparticles.

  16. Bare magnetic nanoparticles as fluorescence quenchers for detection of thrombin.

    PubMed

    Yu, Jiemiao; Yang, Liangrong; Liang, Xiangfeng; Dong, Tingting; Liu, Huizhou

    2015-06-21

    Rapid and sensitive detection of thrombin has very important significance in clinical diagnosis. In this work, bare magnetic iron oxide nanoparticles (magnetic nanoparticles) without any modification were used as fluorescence quenchers. In the absence of thrombin, a fluorescent dye (CY3) labeled thrombin aptamer (named CY3-aptamer) was adsorbed on the surface of magnetic nanoparticles through interaction between a phosphate backbone of the CY3-aptamer and hydroxyl groups on the bare magnetic nanoparticles in binding solution, leading to fluorescence quenching. Once thrombin was introduced, the CY3-aptamer formed a G-quartet structure and combined with thrombin, which resulted in the CY3-aptamer being separated from the magnetic nanoparticles and restoration of fluorescence. This proposed assay took advantage of binding affinity between the CY3-aptamer and thrombin for specificity, and bare magnetic nanoparticles for fluorescence quenching. The fluorescence signal had a good linear relationship with thrombin concentration in the range of 1-60 nM, and the limit of detection for thrombin was estimated as low as 0.5 nM. Furthermore, this method could be applied for other target detection using the corresponding fluorescence labeled aptamer. PMID:25894923

  17. Magnetization reversal dynamics in clusters of single domain Ni nanoparticles

    NASA Astrophysics Data System (ADS)

    Rana, Bivas; Agrawal, Milan; Pal, Semanti; Barman, Anjan

    2010-05-01

    We present the magnetization reversal dynamics of clusters of single domain nickel nanoparticles. Experimental results of magnetization reversal of nickel nanoparticles are completely different from that of bulk nickel and single nickel nanoparticles in terms of the overall shape, coercive field, and the saturation magnetization. Simulations show that a cluster consists of minimum 5×5×3 nanoparticles with no physical overlap between the particles reproduces the loop shape and the coercive field but not the saturation magnetization. However, the same cluster with partially overlapped nanoparticles reasonably reproduces all features of the magnetization reversal due to the presence of both magnetostatic and exchange interactions between the particles. Simulated magnetization images show that the reversal of the cluster occurs through the formation of a C-like state, followed by the creation and annihilation of a vortex like structure, an inverse C-state, and finally, a fully saturated reversed magnetic state. Additional simulations on random clusters show lower coercive field and nearly bulklike saturation magnetization, which are much different than the experimental results. This suggests that the experimental clusters are not totally random or periodically arranged but have a certain amount of ordering.

  18. Enhanced magnetic anisotropy in cobalt-carbide nanoparticles

    NASA Astrophysics Data System (ADS)

    El-Gendy, Ahmed A.; Qian, Meichun; Huba, Zachary J.; Khanna, Shiv N.; Carpenter, Everett E.

    2014-01-01

    An outstanding problem in nano-magnetism is to stabilize the magnetic order in nanoparticles at room temperatures. For ordinary ferromagnetic materials, reduction in size leads to a decrease in the magnetic anisotropy resulting in superparamagnetic relaxations at nanoscopic sizes. In this work, we demonstrate that using wet chemical synthesis, it is possible to stabilize cobalt carbide nanoparticles which have blocking temperatures exceeding 570 K even for particles with magnetic domains of 8 nm. First principles theoretical investigations show that the observed behavior is rooted in the giant magnetocrystalline anisotropies due to controlled mixing between C p- and Co d-states.

  19. FMR study of magnetic nanoparticles embedded in non-magnetic matrix

    Microsoft Academic Search

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

    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

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

    E-print Network

    Paris-Sud XI, Université de

    1 Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields accumulate around the microparticle and form thick anisotropic clouds extended in the direction. In the present work, size and shape of nanoparticle clouds under the simultaneous action of an external uniform

  1. Magnetic Properties of Bio-Synthesized Magnetite Nanoparticles

    SciTech Connect

    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

    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.

  2. Magnetic nanoparticles for medical applications: Progress and challenges

    SciTech Connect

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

    2013-11-13

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

  3. Applications of Magnetic Micro- and Nanoparticles in Biology and Medicine

    NASA Astrophysics Data System (ADS)

    Dobson, J.

    2005-12-01

    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.

  4. Taking the Temperature of the Interiors of Magnetically Heated Nanoparticles

    PubMed Central

    2015-01-01

    The temperature increase inside mesoporous silica nanoparticles induced by encapsulated smaller superparamagnetic nanocrystals in an oscillating magnetic field is measured using a crystalline optical nanothermometer. The detection mechanism is based on the temperature-dependent intensity ratio of two luminescence bands in the upconversion emission spectrum of NaYF4:Yb3+, Er3+. A facile stepwise phase transfer method is developed to construct a dual-core mesoporous silica nanoparticle that contains both a nanoheater and a nanothermometer in its interior. The magnetically induced heating inside the nanoparticles varies with different experimental conditions, including the magnetic field induction power, the exposure time to the magnetic field, and the magnetic nanocrystal size. The temperature increase of the immediate nanoenvironment around the magnetic nanocrystals is monitored continuously during the magnetic oscillating field exposure. The interior of the nanoparticles becomes much hotter than the macroscopic solution and cools to the temperature of the ambient fluid on a time scale of seconds after the magnetic field is turned off. This continuous absolute temperature detection method offers quantitative insight into the nanoenvironment around magnetic materials and opens a path for optimizing local temperature controls for physical and biomedical applications. PMID:24779552

  5. Surfactant Organic Molecules Restore Magnetism in Metal-Oxide Nanoparticle Surfaces

    E-print Network

    Pennycook, Steve

    Surfactant Organic Molecules Restore Magnetism in Metal-Oxide Nanoparticle Surfaces Juan Salafranca ingredient in the fabrication of nanoparticles with optimal magnetic properties. KEYWORDS: Ferrites, metal-oxide nanoparticles, magnetism, electron magnetic chiral dichroism, electron energy loss spectroscopy Metal-oxide

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

    Microsoft Academic Search

    Srinivasan Balakrishnan

    2010-01-01

    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

  7. Synthesis of magnetic nanoparticles by pulsed laser ablation

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  8. Thermoseeds for interstitial magnetic hyperthermia: from bioceramics to nanoparticles

    NASA Astrophysics Data System (ADS)

    Baeza, A.; Arcos, D.; Vallet-Regí, M.

    2013-12-01

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

  9. Preparation of magnetic fluorescent hollow nanoparticles with multi-layer

    NASA Astrophysics Data System (ADS)

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

    2009-07-01

    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.

  10. Biocompatible core-shell magnetic nanoparticles for cancer treatment

    NASA Astrophysics Data System (ADS)

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

    2008-04-01

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

  11. Biocompatible core-shell magnetic nanoparticles for cancer treatment

    SciTech Connect

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

    2008-04-01

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

  12. Interface charge transfer in polypyrrole coated perovskite manganite magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

    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.

  13. A magnonic gas sensor based on magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Matatagui, D.; Kolokoltsev, O. V.; Qureshi, N.; Mejía-Uriarte, E. V.; Saniger, J. M.

    2015-05-01

    In this paper, we propose an innovative, simple and inexpensive gas sensor based on the variation in the magnetic properties of nanoparticles due to their interaction with gases. To measure the nanoparticle response a magnetostatic spin wave (MSW) tunable oscillator has been developed using an yttrium iron garnet (YIG) epitaxial thin film as a delay line (DL). The sensor has been prepared by coating a uniform layer of CuFe2O4 nanoparticles on the YIG film. The unperturbed frequency of the oscillator is determined by a bias magnetic field, which is applied parallel to the YIG film and perpendicularly to the wave propagation direction. In this device, the total bias magnetic field is the superposition of the field of a permanent magnet and the field associated with the layer of magnetic nanoparticles. The perturbation produced in the magnetic properties of the nanoparticle layer due to its interaction with gases induces a frequency shift in the oscillator, allowing the detection of low concentrations of gases. In order to demonstrate the ability of the sensor to detect gases, it has been tested with organic volatile compounds (VOCs) which have harmful effects on human health, such as dimethylformamide, isopropanol and ethanol, or the aromatic hydrocarbons like benzene, toluene and xylene more commonly known by its abbreviation (BTX). All of these were detected with high sensitivity, short response time, and good reproducibility.

  14. Synthesis and Characterization of Polymer-Templated Magnetic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Tamakloe, Beatrice

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

  15. Temperature-induced phenomena in systems of magnetic nanoparticles

    Microsoft Academic Search

    Abdul Wazed Bhuiya

    2009-01-01

    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

  16. Magnetic Core-Shell Morphology of Structurally Uniform Magnetite Nanoparticles

    Microsoft Academic Search

    Kathryn Krycka

    2011-01-01

    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

  17. Lanthanide doped nanoparticles as remote sensors for magnetic fields.

    PubMed

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

    2014-10-01

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

  18. Magnetic-plasmonic bifunctional CoO-Ag heterostructure nanoparticles

    NASA Astrophysics Data System (ADS)

    Yang, Jianhui; Cao, Beibei; Liu, Bin

    2014-03-01

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

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

    PubMed Central

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

    2013-01-01

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

  20. Assembly and magnetic properties of nickel nanoparticles on silicon nanowires

    SciTech Connect

    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

    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.

  1. Oxidation Effect in Cobalt Nanoparticles Magnetic Fluids

    Microsoft Academic Search

    Jong Soo Hong; Jeffrey Pyun; Yong Wook Park; Chul Sung Kim; In-Bo Shim

    2009-01-01

    Cobalt nanoparticles were synthesized by modified thermal decomposition and oxidized in the condition of solution. Crystal structure of fabricated cobalt nanoparticles is determined to be cubic of Fm-3m space group from X-ray diffraction (XRD) measurement. Microstructure of cobalt nanoparticles after the oxidation process show core-shell structure. The particle size and thickness of oxide shell can be controlled by oxidation temperature.

  2. Magnetic Nanoparticle Arrays prepared via Coaxial Electrospinning

    Microsoft Academic Search

    Nikhil Sharma; Hassnain Jaffari; Ismat Shah; Darrin Pochan

    2009-01-01

    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

  3. Preparation of lysozyme imprinted magnetic nanoparticles via surface graft copolymerization.

    PubMed

    Wang, Yanxia; Chai, Zhihua; Sun, Yingjuan; Gao, Ming; Fu, Guoqi

    2015-08-01

    Molecular imprinting as a facile and promising separation technique has received considerable attention because of their high selectivity for target molecules. In this study, we imprinted lysozyme (Lys) on the surface of core-shell magnetic nanoparticles via surface imprinting. The magnetic supports were functionalized with maleic acid and then coated with imprinted polymer layers. The structure and morphology of the resulting magnetic imprinted nanoparticles were characterized by transmission electron microscopy, scanning electron microscope, dynamic light scatting, vibrating sample magnetometer, and thermogravimetric analysis. Binding experiments were carried out to evaluate the properties of magnetic molecularly imprinted polymers (magnetic MIPs) and magnetic non-molecularly imprinted polymers (magnetic NIPs). The protein adsorption results showed that the magnetic MIPs had significant specific recognition toward the template protein and could be easily separated from solution by an external magnetic field. Moreover, the MIPs exhibited fast kinetics for the rebinding of the target protein due to the thin-imprinted layer and showed good reusability by four adsorption-desorption cycles. Therefore, the surface imprinting approach combined with magnetic nanoparticles provided an easy and fast method for the specific recognition of Lys. PMID:26073534

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

    PubMed

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

    2015-03-11

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

  5. The unusual magnetism of nanoparticle LaCoO3

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  6. Multifunctional magnetic and fluorescent core-shell nanoparticles for bioimaging

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  7. A solution phase fabrication of magnetic nanoparticles encapsulated in carbon

    NASA Astrophysics Data System (ADS)

    Wei, Xian-Wen; Zhu, Guo-Xing; Xia, Chuan-Jun; Ye, Yin

    2006-09-01

    To avoid high energy consumption, intensive use of hardware and high cost in the manufacture of nanoparticles encapsulated in carbon, a simple, efficient and economical solution-phase method for the fabrication of FeNi@C nanostructures has been explored. The reaction to the magnetic metal@C structures here is conducted at a relatively low temperature (160 °C) and this strategy can be transferred to prepare other transition metal@C core-shell nanostructures. The saturation magnetization of metal in metal@C nanostructures is similar to those of the corresponding buck metals. Magnetic metal@C nanostructures with magnetic metal nanoparticles inside and a functionalized carbon surface outside may not only provide the opportunity to tailor the magnetic properties for magnetic storage devices and therapeutics but also make possible the loading of other functional molecules (e.g. enzymes, antigens) for clinic diagnostics, molecular biology, bioengineering, and catalysis.

  8. Cell uptake enhancement of folate targeted polymer coated magnetic nanoparticles.

    PubMed

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

    2013-06-01

    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

  9. Resolving 3D magnetism in nanoparticles using polarization analyzed SANS

    Microsoft Academic Search

    K. L. Krycka; R. Booth; J. A. Borchers; W. C. Chen; C. Conlon; T. R. Gentile; C. Hogg; Y. Ijiri; M. Laver; B. B. Maranville; S. A. Majetich; J. J. Rhyne; S. M. Watson

    2009-01-01

    Utilizing a polarized 3He cell as an analyzer we were able to perform a full polarization analysis on small-angle neutron scattering (SANS) data from an ensemble of 7nm magnetite nanoparticles. The results led to clear separation of magnetic and nuclear scattering plus a 3D vectorial decomposition of the magnetism observed. At remanence variation in long-range magnetic correlation length was found

  10. Lymph node localization of non-specific antibody-coated liposomes

    SciTech Connect

    Mangat, S.; Patel, H.M.

    1985-05-20

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

  11. Plasmon nanoparticle superlattices as optical-frequency magnetic metamaterials.

    PubMed

    Alaeian, Hadiseh; Dionne, Jennifer A

    2012-07-01

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

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

    Microsoft Academic Search

    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

    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

  13. Cellular uptake of protein-bound magnetic nanoparticles in pulsed magnetic field.

    PubMed

    Lee, Chia-Haw; Chen, Chao-Bin; Chung, Ting-Hao; Lin, Yu-Sheng; Lee, Wen-Chien

    2010-12-01

    A method for fast delivery of proteins conjugated to superparamagnetic iron oxide nanoparticles (SPION) into mammalian cells by applying a strong magnetic field in pulses was proposed. Firstly, SPION were prepared from an alkaline solution of divalent and trivalent iron ions and covalently bound with protein through the activation of N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide (EDC). After fluorescently labelling, the protein-nanoparticle conjugate was mixed with mammalian cell line and exposed to a pulsed magnetic field for short durations of few milliseconds. Results suggested that superparamagnetic nanoparticles were able to carry proteins into living cells immediately. Cellular internalization of the fluorescently labelled protein-nanoparticle conjugate was proved by the observation of cell fluorescence in a fluorescent microscopy, as well as cell analysis by a flow cytometer. We found that the cellular uptake was accomplished dominantly by the process of bombardment of magnetic nanoparticles. PMID:21121284

  14. A Two-Magnet System to Push Therapeutic Nanoparticles

    PubMed Central

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

    2010-01-01

    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

  15. Physical Justification for Negative Remanent Magnetization in Homogeneous Nanoparticles

    PubMed Central

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

    2014-01-01

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

  16. Multifunctional magnetic nanoparticles for targeted imaging and therapy

    PubMed Central

    McCarthy, Jason R.; Weissleder, Ralph

    2008-01-01

    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. PMID:18508157

  17. Magnetic properties of nanoparticles in {Pd}/{Ni} alloys

    NASA Astrophysics Data System (ADS)

    Nunomura, N.; Hori, H.; Teranishi, T.; Miyake, M.; Yamada, S.

    1998-12-01

    In order to investigate the alloying effect in {Ni}/{Pd} nanoparticles, a special chemical reaction method has been developed to generate a sufficient number of well-conformed Pd ultra-fine particles. Ni concentration dependence on magnetization reveals the existence of a giant magnetic moment effect, where the critical concentration of 6.3 at% is higher than the bulk state one. The higher harmonics intensity of ESR is remarkably enlarged in the alloying particles. The enhanced spectra with ?S = 2 and the broad spectra arise from the nonlinear effect of the isolated nanoparticles with a long spin-lattice relaxation time.

  18. Chemical synthesis of FePt nanoparticles with high alternate current magnetic susceptibility for biomedical applications

    Microsoft Academic Search

    Yoshitaka Kitamoto; Jing-Sha He

    2009-01-01

    The present paper describes ordered alloy FePt nanoparticles with high magnetic susceptibility to alternate current (ac) fields at around room temperature for biomedical applications such as magnetic sensing devices for diagnostics and magnetic hyperthermia for cancer therapy. Since ac magnetic susceptibility takes the maximum value at a temperature near the blocking temperature of magnetic nanoparticles, the blocking temperature of the

  19. Molecular Sensing with Magnetic Nanoparticles Using Magnetic Spectroscopy of Nanoparticle Brownian Motion

    PubMed Central

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

    2013-01-01

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

  20. Magnetic Nanoparticles in-vivo Detection of Transplant Rejection

    NASA Astrophysics Data System (ADS)

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

    2006-03-01

    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.

  1. Properties of magnetic nanoparticles prepared by co-precipitation.

    PubMed

    Kim, Jong-Hee; Kim, Sang-Mun; Kim, Yong-Il

    2014-11-01

    Magnetic nanoparticles were synthesized by the addition of ammonium hydroxide to an iron chloride solution by chemical co-precipitation. In order to examine systematically the crystal phase, average size, and magnetic properties of the magnetic nanoparticles, the following were used as experimental parameters: molar ratio of Fe2+/Fe3+, composition of the iron chloride solution, amount of ammonium hydroxide, reaction temperature, and oxidation time of reaction precipitate. In the processing conditions of Fe2+/Fe3+ ratios of 0.5 and 1.0, iron chloride solutions of 0.1-0.8 m, NH4OH molar ratios of 6-14R, reaction temperatures of 25-80 degrees C, and oxidation times of 5-90 min, the co-precipitated nanoparticles were observed to exist as a single phase of Fe3O4. The average size of the particles was approximately 20 nm, and their magnetization was saturated at about 60 emu/g with superparamagnetism. When the iron chloride solution comprised only Fe2+ ions, the oxidation of the reaction precipitates also developed a Fe3O4 phase. However, the particle size reached 78 nm with increasing oxidation times, and the saturation magnetization increased significantly to 82 emu/g while its coercive force was 150 Oe, which indicated that the nanoparticles were paramagnetic. PMID:25958595

  2. Confinement of magnetic nanoparticles inside multisegmented nanotubes by means of magnetic field gradients

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

    The possibility of confining magnetic nanoparticles inside multisegmented nanotubes by using strong field gradients is considered by means of Monte Carlo simulations. The problem is reduced to the random walk performed by the nanoparticle on the energy landscape produced by the tube's magnetic field. The role of tube material, number of segments, and spacer thickness in the amount of time spent by the particle inside the tube is examined, concluding that it is possible to control the encapsulation time by using different architectures.

  3. Magnetic Core-Shell Morphology of Structurally Uniform Magnetite Nanoparticles

    NASA Astrophysics Data System (ADS)

    Krycka, Kathryn

    2011-03-01

    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. 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.

  4. Selective separation of fluorescent-magnetic nanoparticles with different magnetite-doping levels.

    PubMed

    Park, Sang-Eun; Park, Sang-Joon; Lee, Sang-Wha; Lee, Joong-Kee

    2011-05-01

    Fluorescent-labeled magnetic nanoparticles were explored as a biomedical agent for selective magnetic separation. By adjusting the loading volume of citrate-stabilized magnetites during a sol-gel reaction with silicon alkoxide, magnetites were simultaneously embedded into both the surface and inside the silica matrix, consequently leading to magnetic nanoparticles with different doping levels of magnetites. For endowing them with multifunctional tools in biomedical fields, magnetic nanoparticles were further encapsulated with silica thin layer labeled with fluorescent organic dyes (such as Alexa Fluor 488 and 594). Fluorescent-magnetic nanoparticles with different magnetism successfully displayed the differential separation of fluorescence spectra under an external magnetic field. PMID:21780495

  5. Lanthanide doped nanoparticles as remote sensors for magnetic fields

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    We report the effect of magnetic fields (MFs) on emission Eu-doped NaYF4 nanoparticles. A notable shift in the position of emission bands and the suppressed emission intensity are observed with the MF. These magnetic-optical interactions are explained in terms of the Zeeman effect, enhanced cross-relaxation rate and change of site symmetry.We report the effect of magnetic fields (MFs) on emission Eu-doped NaYF4 nanoparticles. A notable shift in the position of emission bands and the suppressed emission intensity are observed with the MF. These magnetic-optical interactions are explained in terms of the Zeeman effect, enhanced cross-relaxation rate and change of site symmetry. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr02983f

  6. Preparation and characterization of functional silica hybrid magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  7. Magnetic properties of Ni nanoparticles on microporous silica spheres

    Microsoft Academic Search

    Jeffrey F. Godsell; Keith P. Donegan; Joseph M. Tobin; Mark P. Copley; Fernando M. F. Rhen; David J. Otway; Michael A. Morris; Terence O'Donnell; Justin D. Holmes; Saibal Roy

    2010-01-01

    Ni nanoparticles (~32 nm particle diameter) have been synthesized on the walls of microporous (~1 nm pore diameter) silica spheres (~2.6 mum sphere diameter) and characterised magnetically to potentially produce a new class of core (silica micro-spheres)-shell (nanometallic)-type nanocomposite material. These magnetic nanocomposite materials display a characteristic increase in coercivity with reducing temperature. The average particle size has been used

  8. Magnetic properties of Ni nanoparticles on microporous silica spheres

    Microsoft Academic Search

    Jeffrey F. Godsell; Keith P. Donegan; Joseph M. Tobin; Mark P. Copley; Fernando M. F. Rhen; David J. Otway; Michael A. Morris; Terence O’Donnell; Justin D. Holmes; Saibal Roy

    2010-01-01

    Ni nanoparticles (~32nm particle diameter) have been synthesized on the walls of microporous (~1nm pore diameter) silica spheres (~2.6?m sphere diameter) and characterised magnetically to potentially produce a new class of core (silica micro-spheres)-shell (nanometallic)-type nanocomposite material. These magnetic nanocomposite materials display a characteristic increase in coercivity with reducing temperature. The average particle size has been used to calculate the

  9. Magnetic properties of an individual Fe-Cu-B nanoparticle

    SciTech Connect

    Duxin, N.; Pileni, M.P.; Wernsdorfer, W.; Barbara, B.; Benoit, A.; Mailly, D.

    2000-01-11

    Superparamagnetic elongated Fe-Cu-B alloys were prepared in aqueous solution via sodium borohydride reduction of copper and iron dodecyl sulfate, Cu(DS){sub 2} and Fe(DS){sub 2}. The magnetization reversal of an individual Fe-Cu-B nanoparticle can be described by uniform rotation of magnetization and by thermal activation over a single-energy barrier as originally proposed by Neel and Brown.

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

    PubMed

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

    2013-10-22

    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

  11. Magnetic Nanoparticles for Early Detection of Cancer by Magnetic Resonance Imaging

    PubMed Central

    Lin, Wenbin; Hyeon, Taeghwan; Lanza, Gregory M.; Zhang, Miqin; Meade, Thomas J.

    2015-01-01

    This article provides a brief overview of recent progress in the synthesis and functionalization of magnetic nanoparticles and their applications in the early detection of malignant tumors by magnetic resonance imaging (MRI). The intrinsic low sensitivity of MRI necessitates the use of large quantities of exogenous contrast agents in many imaging studies. Magnetic nanoparticles have recently emerged as highly efficient MRI contrast agents because these nanometer-scale materials can carry high payloads while maintaining the ability to move through physiological systems. Superparamagnetic ferrite nanoparticles (such as iron oxide) provide excellent negative contrast enhancement. Recent refinement of synthetic methodologies has led to ferrite nanoparticles with narrow size distributions and high crystallinity. Target-specific tumor imaging becomes possible through functionalization of ferrite nanoparticles with targeting agents to allow for site-specific accumulation. Nanoparticulate contrast agents capable of positive contrast enhancement have recently been developed in order to overcome the drawbacks of negative contrast enhancement afforded by ferrite nanoparticles. These newly developed magnetic nanoparticles have the potential to enable physicians to diagnose cancer at the earliest stage possible and thus can have an enormous impact on more effective cancer treatment.

  12. Synergistic enhancement effect of magnetic nanoparticles on anticancer drug accumulation in cancer cells

    NASA Astrophysics Data System (ADS)

    Zhang, Renyun; Wang, Xuemei; Wu, Chunhui; Song, Min; Li, Jingyuan; Lv, Gang; Zhou, Jian; Chen, Chen; Dai, Yongyuan; Gao, Feng; Fu, Degang; Li, Xiaomao; Guan, Zhiqun; Chen, Baoan

    2006-07-01

    Three kinds of magnetic nanoparticle, tetraheptylammonium capped nanoparticles of Fe3O4, Fe2O3 and Ni have been synthesized, and the synergistic effect of these nanoparticles on the drug accumulation of the anticancer drug daunorubicin in leukaemia cells has been explored. Our observations indicate that the enhancement effect of Fe3O4 nanoparticles is much stronger than that of Fe2O3 and Ni nanoparticles, suggesting that nanoparticle surface chemistry and size as well as the unique properties of the magnetic nanoparticles themselves may contribute to the synergistic enhanced effect of the drug uptake of targeted cancer cells.

  13. Optical and magnetic manipulation of hybrid micro and nanoparticle sensors

    Microsoft Academic Search

    Rodney Ray Agayan

    2008-01-01

    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

  14. Hybrid composites of xanthan and magnetic nanoparticles for cellular uptake.

    PubMed

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

    2013-11-01

    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

  15. Smart drug delivery through DNA/magnetic nanoparticle gates.

    PubMed

    Ruiz-Hernández, Eduardo; Baeza, Alejandro; Vallet-Regí, María

    2011-02-22

    Mesoporous silica nanoparticles can be modified to perform on-demand stimuli-responsive dosing of therapeutic molecules. The silica network was loaded with iron oxide superparamagnetic nanocrystals, providing the potential to perform targeting and magnetic resonance imaging. Single-stranded DNA was immobilized onto the material surface. The complementary DNA sequence was then attached to magnetic nanoparticles. The present work demonstrates that DNA/magnetic nanoparticle conjugates are able to cap the pores of the magnetic silica particles upon hybridization of both DNA strands. Progressive double-stranded DNA melting as a result of temperature increase gave rise to uncapping and the subsequent release of a mesopore-filled model drug, fluorescein. The reversibility of DNA linkage results in an "on-off" release mechanism. Moreover, the magnetic component of the whole system allows reaching hyperthermic temperatures (42-47 °C) under an alternating magnetic field. This feature leaves open the possibility of a remotely triggered drug delivery. Furthermore, due to its capacity to increase the temperature of the surrounding media, this multifunctional device could play an important role in the development of advanced drug delivery systems for thermochemotherapy against cancer. PMID:21250653

  16. Biological Sensors based on Brownian Relaxation of Magnetic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Chung, S.-H.; Hoffmann, A.; Bader, S. D.; Liu, C.; Chen, L.; Kay, B.; Makowski, L.

    2004-03-01

    We present a biological sensing platform that is based on a modification of the dynamic magnetic properties of ferromagnetic nanoparticles suspended in a liquid. For a narrow size range the ac magnetic susceptibility of the ferromagnetic nanoparticles is dominated by Brownian relaxation. By coating the nanoparticles with a suitable ligand the Brownian relaxation and thus the ac magnetic susceptibility can be modified through the binding to the corresponding bio-receptor. The size of the particles has to be large enough to avoid superparamagnetism and at the same time small enough to have a homogeneous single domain magnetization. We demonstrate a proof-of-principle of this concept by using avidin-coated Fe_3O4 particles that are 10 nm in diameter, which were investigated before and after binding to biotinated S-protein and bacteriophage particles. The ac susceptibility measurements show that the magnetic relaxation occurs via a Brownian mechanism; the frequency shift for the peak in the imaginary part of the susceptibility after binding to the target indicates the increase of the hydrodynamic radius. We are currently developing magnetic phage viruses in order to further improve this bio-sensing platform. * Supported by DOE, BES under contract W-31-109-ENG-38, and DARPA under contract 8C67400.

  17. Chemical conjugation of urokinase to magnetic nanoparticles for targeted thrombolysis.

    PubMed

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

    2009-10-01

    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

  18. DOI: 10.1002/adma.200700091 Remotely Triggered Release from Magnetic Nanoparticles**

    E-print Network

    Bhatia, Sangeeta

    DOI: 10.1002/adma.200700091 Remotely Triggered Release from Magnetic Nanoparticles** By Austin M, and Sangeeta N. Bhatia* Multivalent nanoparticles have tremendous potential in the diagnosis and treatment nanoparticle homing, polymers (e.g., polyethylene glycol (PEG)) to improve nanoparticle pharmacokinetics

  19. Rotary transportation of magnetic nanoparticle chains on magnetic thin film array

    NASA Astrophysics Data System (ADS)

    Lee, Chiun Peng; Tsai, Hsin Yi; Lai, Mei Feng

    2012-06-01

    Rotary step like transportation of chains of magnetic nanoparticles along arrays of magnetic discs is demonstrated. The strong magnetic attraction between the magnetic discs and the chains prevents the particle chain from slipping and allows a more controllable and programmable chain transportation. Different types of rotary motions of the chains are observed, and the cell transportation via functionalized particle chains is also shown to demonstrate a potential application in bio transportation.

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

    E-print Network

    Swihart, Mark T.

    and characterization of iron nanoparticles formed by laser-driven pyrolysis of iron carbonyl (Fe(CO)5) vapors. CO2Laser-driven synthesis and magnetic properties of iron nanoparticles Yuanqing He1,4 , Yudhisthira form 6 July 2005 Key words: CO2 laser, aerosol synthesis, magnetic, iron, nanoparticle Abstract

  1. Remote control of ion channels and neurons through magnetic-field heating of nanoparticles

    E-print Network

    Ferkey, Denise

    Remote control of ion channels and neurons through magnetic-field heating of nanoparticles Heng. Here, we show an approach based on radio-frequency magnetic-field heating of nanoparticles to remotely in vivo applications. Although small (30 nm) nanoparticles have been used to induce the aggregation

  2. Enhanced magnetorheological performance of highly uniform magnetic carbon nanoparticles.

    PubMed

    Lee, Seungae; Shin, Keun-Young; Jang, Jyongsik

    2015-05-21

    Magnetic carbon nanoparticles (MC NPs) are prepared on a multi-gram scale through carbonization of iron-doped polypyrrole nanoparticles (PPy NPs). Three different-sized MC NPs (ca. 40, 60 and 90 nm) are prepared and adopted as dispersing materials for magnetorheological (MR) fluids to investigate the influence of particle size on MR properties. The MC NP-based MR fluids exhibit outstanding MR performances compared to the conventional magnetic carbon material-based fluids. In addition, the MR activities are enhanced with decreasing particle diameter and increasing applied magnetic field strength. Furthermore, anti-sedimentation properties are examined in order to achieve in-depth insight into the effect of the particle size on MR fluids. PMID:25959283

  3. Magnetically-Responsive Nanoparticles for Vectored Delivery of Cancer Therapeutics

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    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.

  4. Direct observation of magnetic metastability in individual iron nanoparticles.

    PubMed

    Balan, Ana; Derlet, Peter M; Rodríguez, Arantxa Fraile; Bansmann, Joachim; Yanes, Rocio; Nowak, Ulrich; Kleibert, Armin; Nolting, Frithjof

    2014-03-14

    X-ray photoemission electron microscopy combined with x-ray magnetic circular dichroism is used to study the magnetic properties of individual iron nanoparticles with sizes ranging from 20 down to 8 nm. While the magnetocrystalline anisotropy of bulk iron suggests superparamagnetic behavior in this size range, ferromagnetically blocked particles are also found at all sizes. Spontaneous transitions from the blocked state to the superparamagnetic state are observed in single particles and suggest that the enhanced magnetic energy barriers in the ferromagnetic particles are due to metastable, structurally excited states with unexpected life times. PMID:24679323

  5. Enhanced magnetorheological performance of highly uniform magnetic carbon nanoparticles

    NASA Astrophysics Data System (ADS)

    Lee, Seungae; Shin, Keun-Young; Jang, Jyongsik

    2015-05-01

    Magnetic carbon nanoparticles (MC NPs) are prepared on a multi-gram scale through carbonization of iron-doped polypyrrole nanoparticles (PPy NPs). Three different-sized MC NPs (ca. 40, 60 and 90 nm) are prepared and adopted as dispersing materials for magnetorheological (MR) fluids to investigate the influence of particle size on MR properties. The MC NP-based MR fluids exhibit outstanding MR performances compared to the conventional magnetic carbon material-based fluids. In addition, the MR activities are enhanced with decreasing particle diameter and increasing applied magnetic field strength. Furthermore, anti-sedimentation properties are examined in order to achieve in-depth insight into the effect of the particle size on MR fluids.Magnetic carbon nanoparticles (MC NPs) are prepared on a multi-gram scale through carbonization of iron-doped polypyrrole nanoparticles (PPy NPs). Three different-sized MC NPs (ca. 40, 60 and 90 nm) are prepared and adopted as dispersing materials for magnetorheological (MR) fluids to investigate the influence of particle size on MR properties. The MC NP-based MR fluids exhibit outstanding MR performances compared to the conventional magnetic carbon material-based fluids. In addition, the MR activities are enhanced with decreasing particle diameter and increasing applied magnetic field strength. Furthermore, anti-sedimentation properties are examined in order to achieve in-depth insight into the effect of the particle size on MR fluids. Electronic supplementary information (ESI) available: The reaction mechanism at each step, and high-resolution TEM and SAED pattern analysis. See DOI: 10.1039/c4nr07168a

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

    PubMed

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

    2010-05-01

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

  7. Cell labeling with magnetic nanoparticles: Opportunity for magnetic cell imaging and cell manipulation

    PubMed Central

    2013-01-01

    This tutorial describes a method of controlled cell labeling with citrate-coated ultra small superparamagnetic iron oxide nanoparticles. This method may provide basically all kinds of cells with sufficient magnetization to allow cell detection by high-resolution magnetic resonance imaging (MRI) and to enable potential magnetic manipulation. In order to efficiently exploit labeled cells, quantify the magnetic load and deliver or follow-up magnetic cells, we herein describe the main requirements that should be applied during the labeling procedure. Moreover we present some recommendations for cell detection and quantification by MRI and detail magnetic guiding on some real-case studies in vitro and in vivo. PMID:24564857

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

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

  9. Magnetic disorder in TbAl2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Rojas, D. P.; Fernández Barquín, L.; Sánchez Marcos, J.; Echevarria-Bonet, C.; Espeso, J. I.; Rodríguez Fernández, J.; Rodríguez Fernández, L.; Mathon, M. H.

    2015-07-01

    The magnetic and thermal properties of TbAl2 nanosized alloys (diameters, 12 nm ?slant D?slant 20 nm) obtained by high-energy milling are characterised by specific heat, magnetisation and neutron scattering. The specific heat shows that the ?-anomaly at Curie temperature vanishes when the milling time reaches 300 h and its field variation shows a broad peak around 70 K disclosing a disordered magnetic state. The thermal variation of magnetization follows a Bloch process with a decrease of the stiffness constant and a faster demagnetisation with a quadratic exponent instead of the bulk ordinary {T}3/2-dependence. The magnetic moment reduction in the nanosized alloys follows a 1/D dependence, remarking the role of disordered moment surface. The Rietveld analysis of the neutron diffraction patterns indicates a collinear ferromagnetic structure, with a reduction of the Tb-magnetic moment when decreasing the particle size. The temperature dependent overall magnetic signal of nanoparticles is derived from small-angle neutron scattering. A magnetic nanoparticle structure with an ordered ferromagnetic core and a disordered surface layer is proposed.

  10. Optimizing Magnetite Nanoparticles for Mass Sensitivity in Magnetic Particle Imaging

    SciTech Connect

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

    2011-03-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Dobson, Jon

    2013-03-01

    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.

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

    SciTech Connect

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

    2014-05-07

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

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

    PubMed

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

    2015-04-10

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  15. Functionalized magnetic-fluorescent hybrid nanoparticles for cell labelling

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

    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.

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

    PubMed

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

    2013-02-01

    One of the greatest challenges of nanoparticle cancer therapy is the delivery of adequate numbers of nanoparticles to the tumor site. Iron oxide nanoparticles (IONPs) have many favorable qualities, including their nontoxic composition, the wide range of diameters in which they can be produced, the cell-specific cytotoxic heating that results from their absorption of energy from a nontoxic, external alternating magnetic field (AMF), and the wide variety of functional coatings that can be applied. Although IONPs can be delivered via an intra-tumoral injection to some tumors, the resulting tumor IONP distribution is generally inadequate; additionally, local tumor injections do not allow for the treatment of systemic or multifocal disease. Consequently, the ultimate success of nanoparticle based cancer therapy likely rests with successful systemic, tumor-targeted IONP delivery. In this study, we used a surface-based, bilateral, noninvasive static magnetic field gradient produced by neodymium-boron-iron magnets (80 T/m to 130 T/m in central plane between magnets), a rabbit ear model, and systemically-delivered starch-coated 100 nm magnetic (iron oxide) nanoparticles to demonstrate a spatially-defined increase in the local tissue accumulation of IONPs. In this non-tumor model, the IONPs remained within the local vascular space. It is anticipated that this technique can be used to enhance IONP delivery significantly to the tumor parenchyma/cells. PMID:24073325

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    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.

  18. The Submm and mm Excess of the SMC: Magnetic Dipole Emission from Magnetic Nanoparticles?

    E-print Network

    Draine, B T

    2012-01-01

    The Small Magellanic Cloud (SMC) has surprisingly strong submm and mm-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 gamma-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.

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

    NASA Astrophysics Data System (ADS)

    Draine, B. T.; Hensley, Brandon

    2012-09-01

    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.

  20. Magnetic mesoporous silica nanoparticles for potential delivery of chemotherapeutic drugs and hyperthermia.

    PubMed

    Tao, Cuilian; Zhu, Yufang

    2014-11-01

    Magnetic mesoporous silica (MMS) nanoparticles with controllable magnetization have been synthesized by encapsulating Fe3O4 nanoparticles in a mesoporous silica matrix. The structure, magnetic heating capacity and drug delivery ability of MMS nanoparticles were evaluated. The results showed that MMS nanoparticles had an average particle size of 150 nm and showed low cytotoxicity and efficient cell uptake ability. MMS nanoparticles exhibited a sustained drug release in the medium of pH 5.0, but a very slow release in the medium of pH 7.4. On the other hand, MMS nanoparticles could controllably generate heat to reach the hyperthermia temperature within a short time upon exposure to an alternating magnetic field due to the superparamagnetic behavior and controllable magnetization. Therefore, MMS nanoparticles could provide a promising multifunctional platform for the combination of chemotherapy and hyperthermia for cancer therapy. PMID:25190592

  1. Magnetic Nanoparticles in the Interstella Medium: Emission Spectrum and Polarization

    E-print Network

    Draine, B T

    2012-01-01

    The presence of ferromagnetic or ferrimagnetic nanoparticles in the interstellar medium would give rise to magnetic dipole radiation at microwave and submm frequencies. Such grains may account for the strong mm-wavelength emission observed from a number of low-metallicity galaxies, including the Small Magellanic Cloud. We show how to calculate the absorption and scattering cross sections for such grains, with particular attention to metallic Fe, magnetite Fe3O4, and maghemite gamma-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 we 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. Finally, we present self-consistent dielectric functions for metallic Fe, ma...

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

    PubMed

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

    2006-03-01

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

  3. Magnetic Nanoparticles in the Interstellar Medium: Emission Spectrum and Polarization

    NASA Astrophysics Data System (ADS)

    Draine, B. T.; Hensley, Brandon

    2013-03-01

    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.

  4. MAGNETIC NANOPARTICLES IN THE INTERSTELLAR MEDIUM: EMISSION SPECTRUM AND POLARIZATION

    SciTech Connect

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

    2013-03-10

    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 Fe{sub 3}O{sub 4}, and maghemite {gamma}-Fe{sub 2}O{sub 3}, 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 Fe{sub 3}O{sub 4}, and maghemite {gamma}-Fe{sub 2}O{sub 3}, enabling calculation of absorption and scattering cross sections from microwave to X-ray wavelengths.

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

    PubMed

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

    2014-09-17

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

  6. Characterization of magnetic nanoparticle by dynamic light scattering

    PubMed Central

    2013-01-01

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

  7. Elastic torsion effects in magnetic nanoparticle diblock-copolymer structures.

    PubMed

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

    2010-09-01

    Magnetic properties of thin composite films, consisting of non-interacting polystyrene-coated ?-Fe(2)O(3) (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. PMID:21403273

  8. Faraday Effect in Magnetic and Non-Magnetic Colloidal Nanoparticles in Water

    NASA Astrophysics Data System (ADS)

    Farah, Constantine; Zorba, Serkan; Maxwell, Thomas; Yin, Yadong; He, L.; Ye, M.

    2009-11-01

    We have investigated Faraday Effect in a variety of nanoparticle solutions. Verdet constant of superparamagnetic nanocrystal clusters of magnetite (Fe3O4), diluted in water, is measured as a function of particle size. Particle sizes ranging from 3 to 210 nm, resulted in a nonlinear size dependence in Verdet constant. The relationship between Verdet constant and particle size is possibly due to variation in magnetic domain sizes within the particles. Domain size evolution investigations are underway using X-ray diffraction. Non-magnetic nanoparticle solutions investigated consisted of silver, silver oxide, magnesium oxide, nickel oxide, and carbon nanotubes. Solutions demonstrated diamagnetic and paramagnetic properties, as expected. We believe that Faraday Effect is an efficient method of investigating magnetic properties of nanoparticles.

  9. Magnetoresistance and magnetic properties of Fe3O4 nanoparticle compacts

    Microsoft Academic Search

    Hai Wang; Hong-Wu Zhao; Chang-Sheng Wang; Yin-Jun Wang; Wen-Shan Zhan; Feng-Ying Li; Chang-Qing Jin; Fan-Bin Meng; Yang-Xian Li

    2002-01-01

    In this paper, we report on the magnetic properties of Fe3O4 nanoparticles with different grain sizes under different pressures. In all the samples, the saturated magnetization Ms shows a linear decrease with increasing pressure. The thickness of the magnetic dead layer on the nanoparticle surface under different pressures was roughly estimated, which also increases with increasing pressure. The transport measurements

  10. Magnetoresistance and magnetic properties of Fe3O4 nanoparticle compacts

    Microsoft Academic Search

    Hongwu Zhao; Hai Wang; Changsheng Wang; Wenshan Zhan; Changqing Jin

    2002-01-01

    We have investigated the magnetoresistance and magnetic properties of Fe_3O4 nanoparticles with different grain sizes under different pressures. In all the samples, the saturated magnetization Ms shows a linear decrease with increasing pressure. The thickness of the magnetic dead layer on the nanoparticle surface under different pressures was roughly estimated, which increases also with increasing pressure. Transport measurements of the

  11. CocoreAushell nanoparticles: evolution of magnetic properties in the displacement reaction

    E-print Network

    Krishnan, Kannan M.

    CocoreAushell nanoparticles: evolution of magnetic properties in the displacement reaction Saikat for the gold metal deposition on its surface. Hysteretic magnetic properties of nanoparticles depend critically­shell morphology allow modification and tailoring of the particle properties (e.g., optical, magnetic, catalytic

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

    E-print Network

    Dunin-Borkowski, Rafal E.

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

  13. Magnetic Polystyrene Nanocomposites Reinforced with Magnetite Nanoparticles

    E-print Network

    Guo, John Zhanhu

    sensors,[2] fire retard- ants,[3] microwave absorbers,[4,5] and magnetic recording information.[6 spheres as cores and Fe3O4 as shells. By using slow injection, the thickness of the shell was controlled

  14. Magnetic and structural properties of nanoparticles of nickel oxide

    Microsoft Academic Search

    2006-01-01

    In this dissertation, magnetic properties of NiO nanoparticles (NP) prepared by the sol-gel method in the size range D = 5 nm to 20 nm, with and without oleic acid (OA) coating, are reported. Transmission electron microscopy (TEM) studies show the morphology of the smaller particles to be primarily rod-like, changing over to nearly spherical shapes for D >10 nm.

  15. Magnetic Injection of Nanoparticles into Rat Inner Ears at a Human Head Working Distance

    E-print Network

    Shapiro, Benjamin

    of magnetic fields and forces, single magnets, whether permanent or electro-magnetic, attract ferromagnetict57 1 Magnetic Injection of Nanoparticles into Rat Inner Ears at a Human Head Working Distance: azeem@umd.edu Due to the physics of magnetic fields and forces, any single magnet will always attract

  16. Comparison of schemes for preparing magnetic Fe 3O 4 nanoparticles

    Microsoft Academic Search

    Ruoyu Hong; Jianhua Li; Jian Wang; Hongzhong Li

    2007-01-01

    Magnetic Fe3O4 nanoparticles were prepared by means of coprecipitation using NH3·H2O in water and in alcohol, and using NaOH in water. A series of instruments such as SEM, TEM, HRTEM, FT-IR, XRD and VSM were used to characterize the properties of the magnetic nanoparticles. The results indicated that the magnetism of Fe3O4 nanoparticles synthesized using NH3·H2O in water was the

  17. Measuring and controlling the transport of magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Stephens, Jason R.

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

  18. Magnetic Particle Imaging with Tailored Iron Oxide Nanoparticle Tracers

    PubMed Central

    Ferguson, R. Matthew; Khandhar, Amit P.; Kemp, Scott J.; Arami, Hamed; Saritas, Emine U.; Croft, Laura R.; Konkle, Justin; Goodwill, Patrick W.; Halkola, Aleksi; Rahmer, Jürgen; Borgert, Jörn; Conolly, Steven M.; Krishnan, Kannan M.

    2015-01-01

    Magnetic Particle Imaging (MPI) shows promise for medical imaging, particularly in angiography of patients with chronic kidney disease. As the first biomedical imaging technique that truly depends on nanoscale materials properties, MPI requires highly optimized magnetic nanoparticle tracers to generate quality images. Until now, researchers have relied on tracers optimized for MRI T2*-weighted imaging that are suboptimal for MPI. Here, we describe new tracers tailored to MPI's unique physics, synthesized using an organic-phase process and functionalized to ensure biocompatibility and adequate in vivo circulation time. Tailored tracers showed up to 3x greater SNR and better spatial resolution than existing commercial tracers in MPI images of phantoms. PMID:25438306

  19. Effects of coating on magnetic properties in iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  1. Structural and magnetic properties of sonoelectrocrystallized magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Mosivand, S.; Monzon, L. M. A.; Ackland, K.; Kazeminezhad, I.; Coey, J. M. D.

    2014-02-01

    The effect of ultrasound power on the morphology, structure and magnetic properties of magnetite nanoparticles synthesized from iron electrodes by the electro-oxidation method was investigated. Samples made in aqueous solution in the absence or presence of an organic stabilizer (thiourea, tetramethylammonium chloride, sodium butanoate or ?-cyclodextrine) were characterized by x-ray diffraction, transmission and scanning electron microscopy, magnetometry and Mössbauer spectrometry. The iron is almost all in the form of 20-85 nm particles of slightly nonstoichiometric Fe3-?O4, with ? ? 0.10. Formation of a paramagnetic secondary phase in the presence of sodium butanoate or ?-cyclodextrine is supressed by ultrasound. Specific magnetization of the magnetite nanoparticles ranges from 19 to 90 A m2 kg-1 at room temperature, and it increases with particle size in each series. The particles show no sign of superparamagnetism, and the anhysteretic and practically temperature-independent magnetization curves are associated with a stable magnetic vortex state throughout the size range. The spin structure of the particles and the use of magnetization measurements to detect magnetite in unknown mixtures are discussed.

  2. Magnetic nanoparticle drug delivery systems for targeting tumor

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  3. Ex vivo and in vivo capture and deactivation of circulating tumor cells by dual-antibody-coated nanomaterials.

    PubMed

    Xie, Jingjing; Gao, Yu; Zhao, Rongli; Sinko, Patrick J; Gu, Songen; Wang, Jichuang; Li, Yuanfang; Lu, Yusheng; Yu, Suhong; Wang, Lie; Chen, Shuming; Shao, Jingwei; Jia, Lee

    2015-07-10

    Circulating tumor cells (CTCs) have been detected by us and others in cancer patient blood. However, little is known about how to specifically capture and deactivate CTCs in vivo, which may lead to successful metastasis prevention in asymptomatic cancer survivors after surgery. We hypothesize that the dual antibody conjugates may have the advantage of capturing CTCs specifically over their single antibody counterparts. Here we show that the surface-functionalized dendrimers can be sequentially coated with two antibodies directed to surface biomarkers (EpCAM and Slex) of human colorectal CTCs. The dual antibody-coated dendrimers exhibit a significantly enhanced specificity in capturing CTCs in the presence of interfering blood cells, and in both eight-patient bloods and nude mice administered with the labeled CTCs in comparison to their single antibody-coated counterparts. The dual antibody-coated conjugates down-regulate the captured CTCs. This study provides the first conceptual evidence that two antibodies can be biocompatibly conjugated to a nanomaterial to capture and down-regulate CTCs in vivo with the enhanced specificity. PMID:25933713

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

    PubMed

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

    2012-10-01

    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

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

    PubMed Central

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

    2015-01-01

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

  6. Magnetic nanoparticles: a new tool for antibiotic delivery to sinonasal tissues. Results of preliminary studies.

    PubMed

    Dobretsov, K; Stolyar, S; Lopatin, A

    2015-04-01

    Herein we examined the toxicity, penetration properties and ability of Fe2O3·nH2O magnetic nanoparticles extracted from silt of the Borovoye Lake (Krasnoyarsk, Russia) to bind an antibiotic. Experimental studies were carried out using magnetic nanoparticles alone and after antibiotic exposure in tissue samples from nasal mucosa, cartilage and bone (in vitro). Toxicity of particles was studied in laboratory animals (in vivo). Tissues removed at endonasal surgery (nasal mucosa, cartilage and bone of the nasal septum) were placed in solution containing nanoparticles and exposed to a magnetic field. Distribution of nanoparticles was determined by Perls' reaction. After intravenous injection, possible toxic effects of injected nanoparticles on the organs and tissues of rats were evaluated by histological examination. Binding between the nanoparticles and antibiotic (amoxicillin clavulanate) was studied using infrared spectroscopy. In 30 in vitro experiments, magnetisation of Fe2O3·nH2O nanoparticles resulted in their diffuse infiltration into the mucosa, cartilage and bone tissue of the nose and paranasal sinuses. Intravenous injection of 0.2 ml of magnetic nanoparticles into the rat's tail vein did not result in any changes in parenchymatous organs, and the nanoparticles were completely eliminated from the body within 24 hours. The interaction of nanoparticles with amoxicillin clavulanate was demonstrated by infrared spectroscopy. Positive results of experimental studies provide a basis for further clinical investigations of these magnetic nanoparticles and their use in otorhinolaryngology. PMID:26019393

  7. Magnetic Nanoparticles and microNMR for Diagnostic Applications

    PubMed Central

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

    2012-01-01

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

  8. Magnetic metal nanoparticles coated polyacrylonitrile textiles as microwave absorber

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    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.

  9. Metal nanoparticle fluids with magnetically induced electrical switching properties

    NASA Astrophysics Data System (ADS)

    Kim, Younghoon; Cho, Jinhan

    2013-05-01

    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

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

    PubMed

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

    2015-01-13

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

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

    PubMed

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

    2005-09-01

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

  12. Magnetic nanoparticles with dual functional properties: Drug delivery and magnetic resonance imaging

    Microsoft Academic Search

    Tapan K. Jain; John Richey; Michelle Strand; Diandra L. Leslie-Pelecky; Chris A. Flask; Vinod Labhasetwar

    2008-01-01

    There is significant interest in recent years in developing magnetic nanoparticles (MNPs) having multifunctional characteristics with complimentary roles. In this study, we investigated the drug delivery and magnetic resonance imaging (MRI) properties of our novel oleic acid-coated iron-oxide and pluronic-stabilized MNPs. The drug incorporation efficiency of doxorubicin and paclitaxel (alone or in combination) in MNPs was 74–95%; the drug release

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

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

    PubMed

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

    2014-01-01

    We present the electrostatic complexation between polyelectrolytes and charged nanoparticles. The nanoparticles in solution are ?-Fe2O3 (maghemite) spheres with 8.3 nm diameter and anionic surface charges. The complexation was monitored using three different formulation pathways such as direct mixing, dilution, and dialysis. In the first process, the hybrids were obtained by mixing stock solutions of polymers and nanoparticles. A 'destabilization state' with sharp and intense maximum aggregation was found at charges stoichiometry (isoelectric point). While on the two sides of the isoelectric point, 'long-lived stable clusters state' (arrested states) were observed. Dilution and dialysis processes were based on controlled desalting kinetics according to methods developed in molecular biology. Under an external magnetic field (B?=?0.3 T), from dialysis at isoelectric point and at arrested states, cationic polyelectrolytes can 'paste' these magnetic nanoparticles (NPs) together to yield irregular aggregates (size of 100 ?m) and regular rod-like aggregates, respectively. These straight magnetic wires were fabricated with diameters around 200 nm and lengths comprised between 1 ?m and 0.5 mm. The wires can have either positive or negative charges on their surface. After analyzing their orientational behavior under an external rotating field, we also showed that the wires made from different polyelectrolytes have the same magnetic property. The recipe used a wide range of polyelectrolytes thereby enhancing the versatility and applied potentialities of the method. This simple and general approach presents significant perspective for the fabrication of hybrid functional materials. PMID:24910569

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  16. Improved delivery of magnetic nanoparticles with chemotherapy cancer treatment

    PubMed Central

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    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.

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

    PubMed Central

    2008-01-01

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

  19. Bench-to-bedside translation of magnetic nanoparticles

    PubMed Central

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

    2014-01-01

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

  20. Magnetic nanoparticle imaging using multiple electron paramagnetic resonance activation sequences

    NASA Astrophysics Data System (ADS)

    Coene, A.; Crevecoeur, G.; Dupré, L.

    2015-05-01

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

  1. Preparation and characterization of biofunctionalized chitosan/Fe3O4 magnetic nanoparticles for application in liver magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Song, Xiaoli; Luo, Xiadan; Zhang, Qingqing; Zhu, Aiping; Ji, Lijun; Yan, Caifeng

    2015-08-01

    Biofunctionalized chitosan@Fe3O4 nanoparticles are synthesized by combining Fe3O4 and CS chemically modified with PEG and lactobionic acid in one step. The biofunctionalized nanoparticles are characterized by TEM, X-ray, DLS, zeta-potential and magnetic measurements. The in vitro and in vivo behaviors of the biofunctionalized nanoparticles, especially, the cytotoxicity, the protein resistance, metabolism and iron toxicity are assessed. The functional groups, PEG enable the nanoparticles more biocompatible and the lactobionic acid groups enable liver targeting. The potential applications of the nanoparticles in liver magnetic resonance imaging are confirmed. The results demonstrated that the nanoparticles are suspension stability, non-cytotoxicity, non-tissue toxicity and sensitive in liver magnetic resonance imaging, representing potential tools for applications in the biomedical field.

  2. Quantum dots incorporated magnetic nanoparticles for imaging colon carcinoma cells

    PubMed Central

    2013-01-01

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

  3. Ultrafast magnetization dynamics of cobalt nanoparticles and individual ferromagnetic dots

    NASA Astrophysics Data System (ADS)

    Bigot, Jean-Yves

    2009-03-01

    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).

  4. Magnetic properties of cobalt ferrite nanoparticles synthesized by sol-gel method

    NASA Astrophysics Data System (ADS)

    George, T.; Sunny, A. T.; Varghese, T.

    2015-02-01

    Cobalt ferrite nanoparticles of average size 18 nm are synthesized by sol-gel method and investigated the magnetic properties. The saturation magnetization value calculated from vibration sample magnetometer (VSM) studies for CoFe2O4 is lower than the reported value for the bulk. The magnetization curves demonstrate a trend towards the superparamagnetic behavior of the as-prepared CoFe2O4 nanoparticles. The microwave magnetic parameters show a decreasing trend with the increase of frequency.

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

    Microsoft Academic Search

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

    2007-01-01

    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

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

    Microsoft Academic Search

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

    2009-01-01

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

  7. Effect of spacer layer thickness on magnetic interactions in self-assembled single domain iron nanoparticles

    E-print Network

    Pennycook, Steve

    Effect of spacer layer thickness on magnetic interactions in self-assembled single domain iron been studied as a function of spacer layer thickness. Alumina as well as iron nanoparticles were 2008 The magnetic characteristics of iron nanoparticles embedded in an alumina thin film matrix have

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

    NASA Astrophysics Data System (ADS)

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

    2005-05-01

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

  9. Synthesis of ferrofluid with magnetic nanoparticles by sonochemical method for MRI contrast agent

    Microsoft Academic Search

    Eun Hee Kim; Hyo Sook Lee; Byung Kook Kwak; Byung-Kee Kim

    2005-01-01

    Superparamagnetic iron oxide nanoparticles (SPIO) having high magnetization (83 emu\\/g) and crystallinity were synthesized by using a sonochemical method. Ferrofluids from these nanoparticles coated with oleic acid as a surfactant were prepared for magnetic resonance imaging (MRI) contrast agent. The coated SPIO could be easily dispersed in chitosan, and the hydrodynamic diameter of the coated SPIO in the chitosan solution

  10. Synthesis of ferrofluid with magnetic nanoparticles by sonochemical method for MRI contrast agent

    Microsoft Academic Search

    Eun Hee Kim; Hyo Sook Lee; Byung Kook Kwak; Byung-Kee Kim

    2005-01-01

    Superparamagnetic iron oxide nanoparticles (SPIO) having high magnetization (83emu\\/g) and crystallinity were synthesized by using a sonochemical method. Ferrofluids from these nanoparticles coated with oleic acid as a surfactant were prepared for magnetic resonance imaging (MRI) contrast agent. The coated SPIO could be easily dispersed in chitosan, and the hydrodynamic diameter of the coated SPIO in the chitosan solution was

  11. Observations of oxidation mechanisms and kinetics in faceted FeCo magnetic nanoparticles

    E-print Network

    McHenry, Michael E.

    Observations of oxidation mechanisms and kinetics in faceted FeCo magnetic nanoparticles N. J the as received size. © 2010 American Institute of Physics. doi:10.1063/1.3334197 I. INTRODUCTION FeCo needs to be investigated, noting how the oxide couples to the core of FeCo. FeCo magnetic nanoparticles

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

    NASA Astrophysics Data System (ADS)

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

    2008-04-01

    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 100nm. 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 180s led to deposition of 3.5wt% 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?M18kOe=11.3kG, 4?Mr=11kG, and Hci>20kOe with a smooth demagnetization curve.

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

    PubMed

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

    2014-03-01

    When a micron-sized magnetizable particle is introduced into a suspension of nanosized magnetic particles, the nanoparticles accumulate around the microparticle and form thick anisotropic clouds extended in the direction of the applied magnetic field. This phenomenon promotes colloidal stabilization of bimodal magnetic suspensions and allows efficient magnetic separation of nanoparticles used in bioanalysis and water purification. In the present work, the size and shape of nanoparticle clouds under the simultaneous action of an external uniform magnetic field and the flow have been studied in detail. In experiments, a dilute suspension of iron oxide nanoclusters (of a mean diameter of 60 nm) was pushed through a thin slit channel with the nickel microspheres (of a mean diameter of 50 ?m) attached to the channel wall. The behavior of nanocluster clouds was observed in the steady state using an optical microscope. In the presence of strong enough flow, the size of the clouds monotonically decreases with increasing flow speed in both longitudinal and transverse magnetic fields. This is qualitatively explained by enhancement of hydrodynamic forces washing the nanoclusters away from the clouds. In the longitudinal field, the flow induces asymmetry of the front and the back clouds. To explain the flow and the field effects on the clouds, we have developed a simple model based on the balance of the stresses and particle fluxes on the cloud surface. This model, applied to the case of the magnetic field parallel to the flow, captures reasonably well the flow effect on the size and shape of the cloud and reveals that the only dimensionless parameter governing the cloud size is the ratio of hydrodynamic-to-magnetic forces-the Mason number. At strong magnetic interactions considered in the present work (dipolar coupling parameter ??2), the Brownian motion seems not to affect the cloud behavior. PMID:24730845

  14. Recent patents and advances on applications of magnetic nanoparticles and thin films in cell manipulation.

    PubMed

    Abedini-Nassab, Roozbeh; Eslamian, Morteza

    2014-01-01

    Cell manipulation is instrumental in most biological applications. One of the most promising methods in handling cells and other biological particles is the magnetic manipulation technique. In this technique, magnetic nanoparticles are employed to magnetize cells. Such cells then can be manipulated, sorted, or separated by applying an external magnetic field. In this work, first recent works and patents on the synthesis methods used for producing magnetic nanoparticles are investigated. These methods include co-precipitation, solvothermal, electrical wire explosion, microemulsion, laser pyrolysis, spray pyrolysis and carbon reduction. Then recent patents and articles on surface modification and functionalization of magnetic nanoparticles using polymers, dithiocarbamate, superparamagnetic shells, antibodies, graphene shells, and fluorescent materials are reviewed. Finally, different techniques on magnetic cell manipulation, such as direct attaching of magnetic particles to cells, employing intercellular markers or extra support molecules, as well as magnetic thin films, microfluidic channels and magnetic beads, are studied. PMID:25336173

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

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    PubMed Central

    2012-01-01

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

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

    DOEpatents

    Huber, Dale L. (Albuquerque, NM)

    2011-07-05

    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.

  18. Spectroscopic characterization of magnetic Fe3O4@Au core shell nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  19. Recent advances in magnetic nanoparticles with bulk-like properties

    NASA Astrophysics Data System (ADS)

    Batlle, Xavier

    2013-03-01

    Magnetic nanoparticles (NP) are an excellent example of nanostructured materials and exhibit fascinating properties with applications in high-density recording and biomedicine. Controlling the effects of the nanostructure and surface chemistry and magnetism at the monolayer level have become relevant issues. As the size is reduced below 100 nm, deviations from bulk behavior have been attributed to finite-size effects and changes in the magnetic ordering at the surface, thus giving rise to a significant decrease in the magnetization and increase in the magnetic anisotropy. The existence of a surface spin glass-like state due to magnetic frustration has been widely suggested in ferrimagnetic NP. However, in this talk, we will show that high crystal quality magnetite Fe3-xO4 NP of about a few nanometers in diameter and coated with different organic surfactants display bulk-like structural, magnetic and electronic properties. Magnetic measurements, transmission electron microscopy, X-ray absorption and magnetic circular dichroism and Monte Carlo simulations, evidenced that none of the usual particle-like behavior is observed in high quality NP of a few nm. Consequently, the magnetic and electronic disorder phenomena typically observed in those single-phase ferrimagnetic NP should not be considered as an intrinsic effect. We also performed a real-space characterization at the sub-nanometer scale, combining scanning transmission electron microscopy, electron energy loss spectroscopy and electron magnetic chiral dichroism. For the first time, we found that the surface magnetization is as high as about 70% of that of the core. The comparison to density functional theory suggested the relevance of the strong surface bond between the Fe ions and the organic surfactant. All the foregoing demonstrates the key role of both the crystal quality and surface bond on the physical properties of ferrimagnetic NP and paves the way to the fabrication of the next generation of NP with optimal magnetic properties. Some bio-applications will also be discussed. In collaboration with A Labarta, N Perez, O Iglesias, A Fraile, C Moya(U Barcelona); A Roca, MP Morales, CJ Serna (ICMM-CSIC); F Bartolome, LM Garcia, J. Bartolome (CSIC-U Zaragoza); R Mejias, DF Barber (CNB-CSIC); M Varela, J Gazquez, J Salafranca, SJ Pennycook (ORNL), ST Pantelides (Vanderbilt U).

  20. Functionalization of whole?cell bacterial reporters with magnetic nanoparticles

    PubMed Central

    Zhang, Dayi; Fakhrullin, Rawil F.; Özmen, Mustafa; Wang, Hui; Wang, Jian; Paunov, Vesselin N.; Li, Guanghe; Huang, Wei E.

    2011-01-01

    Summary We developed a biocompatible and highly efficient approach for functionalization of bacterial cell wall with magnetic nanoparticles (MNPs). Three Acinetobacter baylyi ADP1 chromosomally based bioreporters, which were genetically engineered to express bioluminescence in response to salicylate, toluene/xylene and alkanes, were functionalized with 18?±?3?nm iron oxide MNPs to acquire magnetic function. The efficiency of MNPs functionalization of Acinetobacter bioreporters was 99.96?±?0.01%. The MNPs?functionalized bioreporters (MFBs) can be remotely controlled and collected by an external magnetic field. The MFBs were all viable and functional as good as the native cells in terms of sensitivity, specificity and quantitative response. More importantly, we demonstrated that salicylate sensing MFBs can be applied to sediments and garden soils, and semi?quantitatively detect salicylate in those samples by discriminably recovering MFBs with a permanent magnet. The magnetically functionalized cells are especially useful to complex environments in which the indigenous cells, particles and impurities may interfere with direct measurement of bioreporter cells and conventional filtration is not applicable to distinguish and harvest bioreporters. The approach described here provides a powerful tool to remotely control and selectively manipulate MNPs?functionalized cells in water and soils. It would have a potential in the application of environmental microbiology, such as bioremediation enhancement and environment monitoring and assessment. PMID:21255376

  1. Scaffold-independent Patterning of Cells using Magnetic Nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  2. Potential of magnetic nanoparticles for targeted drug delivery

    PubMed Central

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

    2012-01-01

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

  3. Functionalization of whole-cell bacterial reporters with magnetic nanoparticle.

    PubMed

    Zhang, Dayi; Fakhrullin, Rawil F; Özmen, Mustafa; Wang, Hui; Wang, Jian; Paunov, Vesselin N; Li, Guanghe; Huang, Wei E

    2011-01-01

    We developed a biocompatible and highly efficient approach for functionalization of bacterial cell wall with magnetic nanoparticles (MNPs). Three Acinetobacter baylyi ADP1 chromosomally based bioreporters, which were genetically engineered to express bioluminescence in response to salicylate, toluene/ xylene and alkanes, were functionalized with 18 3 nm iron oxide MNPs to acquire magnetic function. The efficiency of MNPs functionalization of Acinetobacter bioreporters was 99.96 0.01%. The MNPs-functionalized bioreporters (MFBs) can be remotely controlled and collected by an external magnetic field. The MFBs were all viable and functional as good as the native cells in terms of sensitivity, specificity and quantitative response. More importantly, we demonstrated that salicylate sensing MFBs can be applied to sediments and garden soils, and semiquantitatively detect salicylate in those samples by discriminably recovering MFBs with a permanent magnet. The magnetically functionalized cells are especially useful to complex environments in which the indigenous cells, particles and impurities may interfere with direct measurement of bioreporter cells and conventional filtration is not applicable to distinguish and harvest bioreporters. The approach described here provides a powerful tool to remotely control and selectively manipulate MNPs-unctionalized cells in water and soils. It would have a potential in the application of environmental microbiology, such as bioremediation enhancement and environment monitoring and assessment. PMID:21255376

  4. Highly magnetic iron carbide nanoparticles as effective T2 contrast agents

    NASA Astrophysics Data System (ADS)

    Huang, Guoming; Hu, Juan; Zhang, Hui; Zhou, Zijian; Chi, Xiaoqin; Gao, Jinhao

    2013-12-01

    This paper reports that iron carbide nanoparticles with high air-stability and strong saturation magnetization can serve as effective T2 contrast agents for magnetic resonance imaging. Fe5C2 nanoparticles (~20 nm in diameter) exhibit strong contrast enhancement with an r2 value of 283.2 mM-1 S-1, which is about twice as high as that of spherical Fe3O4 nanoparticles (~140.9 mM-1 S-1). In vivo experiments demonstrate that Fe5C2 nanoparticles are able to produce much more significant MRI contrast enhancement than conventional Fe3O4 nanoparticles in living subjects, which holds great promise in biomedical applications.This paper reports that iron carbide nanoparticles with high air-stability and strong saturation magnetization can serve as effective T2 contrast agents for magnetic resonance imaging. Fe5C2 nanoparticles (~20 nm in diameter) exhibit strong contrast enhancement with an r2 value of 283.2 mM-1 S-1, which is about twice as high as that of spherical Fe3O4 nanoparticles (~140.9 mM-1 S-1). In vivo experiments demonstrate that Fe5C2 nanoparticles are able to produce much more significant MRI contrast enhancement than conventional Fe3O4 nanoparticles in living subjects, which holds great promise in biomedical applications. Electronic supplementary information (ESI) available: Supplementary figures and experimental details. See DOI: 10.1039/c3nr04691e

  5. Characterization of Magnetic NiFe Nanoparticles with Controlled Bimetallic Composition

    SciTech Connect

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

    2014-02-25

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

  6. Antibacterial activity of magnetic iron oxide nanoparticles synthesized by laser ablation in liquid.

    PubMed

    Ismail, Raid A; Sulaiman, Ghassan M; Abdulrahman, Safa A; Marzoog, Thorria R

    2015-08-01

    In this study, (50-110nm) magnetic iron oxide (?-Fe2O3) nanoparticles were synthesized by pulsed laser ablation of iron target in dimethylformamide (DMF) and sodium dodecyl sulfate (SDS) solutions. The structural properties of the synthesized nanoparticles were investigated by using Fourier Transform Infrared (FT-IR) spectroscopy, UV-VIS absorption, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). The effect of laser fluence on the characteristics of these nanoparticles was studied. Antibacterial activities of iron oxide nanoparticles were tested against Gram-positive; Staphylococcus aureus and Gram-negative; Escherichia coli, Pseudomonas aeruginosa and Serratia marcescens. The results showed a noteworthy inhibition on both bacterial strains. The preparation conditions were found to affect significantly the antibacterial activity of these nanoparticles. The synthesized magnetic nanoparticles were used to capture rapidly S. aureus bacteria under the magnetic field effect. PMID:26042717

  7. Cancer Theranostics: The Rise of Targeted Magnetic Nanoparticles

    PubMed Central

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

    2011-01-01

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

  8. Bioconjugated magnetic nanoparticles for the detection of bacteria.

    PubMed

    Chu, Yu W; Engebretson, David A; Carey, James R

    2013-12-01

    Blood culture is traditionally a time-consuming method and has not changed significantly in several decades. Using nanotechnology, such as the use of magnetic nanoparticles (MNPs), the blood culture process may be streamlined. An important advantage of using MNPs to capture bacteria is the simple separation of bacteria from biological samples using magnets. Indeed, high bacteria capture efficiencies have been realized using MNPs. The binding events between MNPs and bacteria can be tightly controlled through carefully selected biorecognition events, using molecules such as vancomycin, daptomycin, antibodies, and others. These biomolecules can be readily conjugated onto MNPs followed by tethering to bacteria, thus enabling detection using the beacon produced by the bacteria conjugated MNPs. Methods to prepare bioconjugated MNPs and their performance with bacteria are reviewed. Finally, future directions on bacteria detection using giant magnetoresistance (GMR) biosensors are discussed. PMID:24266251

  9. Magnetic liposomes based on nickel ferrite nanoparticles for biomedical applications.

    PubMed

    Rodrigues, Ana Rita O; Gomes, I T; Almeida, Bernardo G; Araújo, J P; Castanheira, Elisabete M S; Coutinho, Paulo J G

    2015-07-21

    Nickel ferrite nanoparticles with superparamagnetic behavior at room temperature were synthesized using a coprecipitation method. These magnetic nanoparticles were either covered with a lipid bilayer, forming dry magnetic liposomes (DMLs), or entrapped in liposomes, originating aqueous magnetoliposomes (AMLs). A new and promising method for the synthesis of DMLs is described. The presence of the lipid bilayer in DMLs was confirmed by FRET (Förster Resonance Energy Transfer) measurements between the fluorescent-labeled lipids NBD-C12-HPC (NBD acting as a donor) included in the second lipid layer and rhodamine B-DOPE (acceptor) in the first lipid layer. An average donor-acceptor distance of 3 nm was estimated. Assays of the non-specific interactions of magnetoliposomes with biological membranes (modeled using giant unilamellar vesicles, GUVs) were performed. Membrane fusion between both aqueous and dry magnetoliposomes and GUVs was confirmed by FRET, which is an important result regarding applications of these systems both as hyperthermia agents and antitumor drug nanocarriers. PMID:26095537

  10. Rapid Immunoenzyme Assay of Aflatoxin B1 Using Magnetic Nanoparticles

    PubMed Central

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

    2014-01-01

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

  11. Magnetoabsorption and magnetic hysteresis in Ni ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Grancharov, Stephanie G.

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

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

    PubMed

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

    2013-01-01

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

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed Central

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

    2011-01-01

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

  16. Synthesis and Characterisation of Pure Cobalt Magnetic Nanoparticle by Metal Reduction

    NASA Astrophysics Data System (ADS)

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

    2009-06-01

    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 was studied. In addition, different stirring rate were applied while the syntheses were executed since it is believe that different rpm (revolution per minute) produce different impact to the particles growth. In order to control the particles size, combination of trialkylphosphine and oleic acid were used to produce tight ligands shell and allow particles to grow steadily. Samples of Co nanoparticles lesser than 15 nm has been prepared and discussed. From the analyses of transmission electron microscopy (TEM), the resultant particles were characterised to be highly crystalline. It was observed that the mean diameter decreased with increasing of the stirring rate.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  18. Influence of surface segregation on magnetic properties of FePt nanoparticles

    SciTech Connect

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

    2013-09-23

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

  19. Surfactant organic molecules restore magnetism in metal-oxide nanoparticle surfaces.

    PubMed

    Salafranca, Juan; Gazquez, Jaume; Pérez, Nicolás; Labarta, Amílcar; Pantelides, Sokrates T; Pennycook, Stephen J; Batlle, Xavier; Varela, Maria

    2012-05-01

    The properties of magnetic nanoparticles tend to be depressed by the unavoidable presence of a magnetically inactive surface layer. However, outstanding magnetic properties with a room-temperature magnetization near the bulk value can be produced by high-temperature synthesis methods involving capping with organic acid. The capping molecules are not magnetic, so the origin of the enhanced magnetization remains elusive. In this work, we present a real-space characterization on the subnanometer scale of the magnetic, chemical, and structural properties of iron-oxide nanoparticles via aberration-corrected scanning transmission electron microscopy. For the first time, electron magnetic chiral dichroism is used to map the magnetization of nanoparticles in real space with subnanometer spatial resolution. We find that the surface of the nanoparticles is magnetically ordered. Combining the results with density functional calculations, we establish how magnetization is restored in the surface layer. The bonding with the acid's O atoms results in O-Fe atomic configuration and distances close to bulk values. We conclude that the nature and number of molecules in the capping layer is an essential ingredient in the fabrication of nanoparticles with optimal magnetic properties. PMID:22497711

  20. Release of magnetic nanoparticles from cell-encapsulating biodegradable nanobiomaterials.

    PubMed

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

    2012-08-28

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

  1. Release of Magnetic Nanoparticles from Cell-Encapsulating Biodegradable Nanobiomaterials

    PubMed Central

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

    2013-01-01

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

  2. Controlled assembly of magnetic nanoparticles on microbubbles for multimodal imaging.

    PubMed

    Duan, Lei; Yang, Fang; Song, Lina; Fang, Kun; Tian, Jilai; Liang, Yijun; Li, Mingxi; Xu, Ning; Chen, Zhongda; Zhang, Yu; Gu, Ning

    2015-07-01

    Magnetic microbubbles (MMBs) consisting of microbubbles (MBs) and magnetic nanoparticles (MNPs) were synthesized for use as novel markers for improving multifunctional biomedical imaging. The MMBs were fabricated by assembling MNPs in different concentrations on the surfaces of MBs. The relationships between the structure, magnetic properties, stability of the MMBs, and their use in magnetic resonance/ultrasound (MR/US) dual imaging applications were determined. The MNPs used were NPs of 3-aminopropyltriethoxysilane (APTS)-functionalized superparamagnetic iron oxide ?-Fe2O3 (SPIO). SPIO was assembled on the surfaces of polymer MBs using a "surface-coating" approach. An analysis of the underlying mechanism showed that the synergistic effects of covalent coupling, electrostatic adsorption, and aggregation of the MNPs allowed them to be unevenly assembled in large amounts on the surfaces of the MBs. With an increase in the MNP loading amount, the magnetic properties of the MMBs improved significantly; in this way, the shell structure and mechanical properties of the MMBs could be modified. For surface densities ranging from 2.45 × 10(-7) ?g per MMB to 8.45 × 10(-7) ?g per MMB, in vitro MR/US imaging experiments showed that, with an increase in the number of MNPs on the surfaces of the MBs, the MMBs exhibited better T2 MR imaging contrast, as well as an increase in the US contrast for longer durations. In vivo experiments also showed that, by optimizing the structure of the MMBs, enhanced MR/US dual-modality image signals could be obtained for mouse tumors. Therefore, by adjusting the shell composition of MBs through the assembly of MNPs in different concentrations, MMBs with good magnetic and acoustic properties for MR/US dual-modality imaging contrast agents could be obtained. PMID:26061750

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

    NASA Astrophysics Data System (ADS)

    Demas, Vasiliki; Lowery, Thomas J.

    2011-02-01

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

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

    Microsoft Academic Search

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

    2010-01-01

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

  5. Simplified unified model for estimating the motion of magnetic nanoparticles within electrohydrodynamic field.

    PubMed

    Seo, Hyeon-Seok; Lee, Sangyoup; Lee, Jong-Chul

    2014-11-01

    In previous research, we studied the electrical breakdown characteristics of a transformer oil-based magnetic fluid; mailnly, those were carried out by the experimental measurements. The first study was aimed at enhancing the dielectric breakdown voltage of transformer oil by adding magnetic nanoparticles experimentally under the official testing condition of dielectric liquids. The next study was focused on explaining the reason why the dielectric characterisitics of the fluids were changed through optically visualizing the particles motion in a microchannel using an optical microscopic measurement and numerically calculating the dielectrophoretic force induced in the fluids with considering only the properties of magnetic nanoparticles. In this study, we developed a simplified unified model for calculating further the motion of magnetic nanoparticles suspended in the presence of electrohydrodynamic field using the COMSOL multiphysics finite element simulation suite and investigated the effects of magnetic nanoparticle dielectrophoretic activity aimed at enhancing the electrical breakdown characteristics of transformer oil. PMID:25958577

  6. Microstructural and magnetic properties of ZnO:TM (TM=Co,Mn) diluted magnetic semiconducting nanoparticles

    Microsoft Academic Search

    S. K. Mandal; A. K. Das; T. K. Nath; Debjani Karmakar; B. Satpati

    2006-01-01

    We have investigated the structural and the magnetic properties of 3d transition metal (TM) doped Zn1-xTMxO (TM=Co,Mn) diluted magnetic semiconducting nanoparticles for different doping concentrations (0<=x<=0.4) synthesized by chemical ``pyrophoric reaction process.'' From x-ray diffraction measurements the solubility limits of Co and Mn in ZnO nanoparticles are found to be strongly dependent on growth (calcinations) temperature (Tg). The highest solubility

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

    PubMed Central

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

    2010-01-01

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

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

    PubMed

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

    2008-02-01

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

  9. Sensing magnetic nanoparticles using nano-confined ferromagnetic resonances in a magnonic crystal

    NASA Astrophysics Data System (ADS)

    Metaxas, P. J.; Sushruth, M.; Begley, R. A.; Ding, J.; Woodward, R. C.; Maksymov, I. S.; Albert, M.; Wang, W.; Fangohr, H.; Adeyeye, A. O.; Kostylev, M.

    2015-06-01

    We experimentally demonstrate the use of the magnetic-field-dependence of highly spatially confined, GHz-frequency ferromagnetic resonances for the detection of magnetic nanoparticles using an anti-dot-based magnonic crystal. The stray magnetic fields of nanoparticles within the anti-dots modify nano-confined ferromagnetic resonances in the surrounding periodically nanopatterned magnonic crystal, generating easily measurable resonance peak shifts. The shifts are comparable to the resonance linewidths for high anti-dot filling fractions with their signs and magnitudes dependent upon the mode localization, consistent with micromagnetic simulation results. This is an encouraging result for the development of frequency-based nanoparticle detectors for nano-scale biosensing.

  10. Calibration Phantom for Quantitative Tomography Analysis of Biodistribution of Magnetic Nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  11. Z-STEM Imaging of Chemical Ordering in FePt Magnetic Nanoparticles

    E-print Network

    Pennycook, Steve

    Z-STEM Imaging of Chemical Ordering in FePt Magnetic Nanoparticles J.E. Wittig, M.S. Wellons and C of the ordered structure. HAADF-STEM, is being used to investigate the development of L10 order in FePt nanoparticles, both ex-situ and in-situ. Accomplishment: FePt nanoparticles of 3.8 nm average diameter were

  12. Pluronic\\/chitosan shell cross-linked nanocapsules encapsulating magnetic nanoparticles

    Microsoft Academic Search

    Ki Hyun Bae; Young Jin Ha; Chunsoo Kim; Kyu-Ri Lee; Tae Gwan Park

    2008-01-01

    We have developed novel Pluronic\\/chitosan nanocapsules encapsulating iron oxide nanoparticles. These nanocapsules were produced by dispersing hydrophobically-modified iron oxide nanoparticles and amine-reactive Pluronic derivatives in an organic solvent, and subsequently emulsification in an aqueous chitosan solution by ultrasonication. The resultant shell cross-linked nanocapsules had a unique core\\/shell type nanoreservoir architecture: an inner core encapsulating magnetic nanoparticles and a hydrophilic Pluronic\\/chitosan

  13. Novel synthesis of mannosamine conjugated magnetic nanoparticles for purification and stabilization of human lysosomal ?-mannosidase

    Microsoft Academic Search

    Zahoor Qadir Samra; Muhammad Amin Athar

    2009-01-01

    Human ?-mannosidase (MANB) was purified to homogeneity directly from lysosomes by using mannosamine conjugated magnetic (Fe3O4) nanoparticles, DE-52 cellulose, and sephadex G-200 chromatography. Fe3O4 nanoparticles were synthesized and utilized ammonia to attach the amino group on the nanoparticles. The particles were covalently\\u000a attached with D-mannosamine by cross linker glutaraldehyde and confirmed by FTIR spectroscopy. In FTIR analysis, the peaks\\u000a appeared

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  15. Interactions and magnetic relaxation in boron doped Mn3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Laha, S. S.; Mukherjee, R.; Lawes, G.

    2014-04-01

    We have studied magnetic interactions in phase pure Mn3O4 and composite Mn2O3/Mn3O4 nanoparticle systems having different interparticle separations between the Mn3O4 ferrimagnetic cores. We characterized the morphology and structure of these nanoparticles using x-ray diffraction and transmission electron microscopy. We find that the incorporation of boron stabilizes the Mn3O4 spinel structure resulting in the formation of phase pure nanoparticles, while in the absence of boron, the sample consists of both Mn3O4 and antiferromagnetic Mn2O3 nanoparticles. We correlate the morphology of these systems with their magnetic properties using ac susceptibility studies. The low temperature frequency dependent relaxation exhibits larger magnetic interactions in the phase pure Mn3O4 nanoparticles as compared to the Mn3O4/Mn2O3 composites, which we attribute to differences in the separation between the ferrimagnetic cores in these two samples.

  16. Nanoparticle Pharmacokinetic Profiling in vivo using Magnetic Resonance Imaging

    PubMed Central

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

    2008-01-01

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

  17. Magnetic properties of polypyrrole-coated iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2005-09-01

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

  18. Targeted fluorescent magnetic nanoparticles for imaging of human breast cancer

    PubMed Central

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

    2014-01-01

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

  19. Development of a Magnetic Nanoparticle Susceptibility Magnitude Imaging Array

    PubMed Central

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

    2014-01-01

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

  20. Magnetic tumor targeting of ?-glucosidase immobilized iron oxide nanoparticles.

    PubMed

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

    2013-09-20

    Directed enzyme/prodrug therapy (DEPT) has promising application for cancer therapy. However, most current DEPT strategies face shortcomings such as the loss of enzyme activity during preparation, low delivery and transduction efficiency in vivo and difficultly of monitoring. In this study, a novel magnetic directed enzyme/prodrug therapy (MDEPT) was set up by conjugating ?-glucosidase (?-Glu) to aminated, starch-coated, iron oxide magnetic iron oxide nanoparticles (MNPs), abbreviated as ?-Glu-MNP, using glutaraldehyde as the crosslinker. This ?-Glu-MNP was then characterized in detail by size distribution, zeta potential, FTIR spectra, TEM, SQUID and magnetophoretic mobility analysis. Compared to free enzyme, the conjugated ?-Glu on MNPs retained 85.54% ± 6.9% relative activity and showed much better temperature stability. The animal study results showed that ?-Glu-MNP displays preferable pharmacokinetics characteristics in relation to MNPs. With an adscititious magnetic field on the surface of a tumor, a significant quantity of ?-Glu-MNP was selectively delivered into a subcutaneous tumor of a glioma-bearing mouse. Remarkably, the enzyme activity of the delivered ?-Glu in tumor lesions showed as high as 20.123±5.022 mU g(-1) tissue with 2.14 of tumor/non-tumor ?-Glu activity. PMID:23974977

  1. Magnetic tumor targeting of ?-glucosidase immobilized iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  2. Magnetic properties of TOAB-capped CuO nanoparticles.

    NASA Astrophysics Data System (ADS)

    Seehra, M.; Punnoose, A.; Mahamuni, S.

    2002-03-01

    Synthesis of CuO nanoparticles (NP) capped with TOAB (tetraoctylammonium bromide) and their structural properties were reported recently [1]. Here we report on the magnetic properties of the TOAB-capped CuO-NP of size 4, 6 and 10 nm and compare these properties with those of uncapped CuO-NP in the size range of 6.6-37 nm described in the above abstract [2] and in a recent publication [3]. Temperature (5 K 350 K) and magnetic field (up to 55 kOe) variations of magnetization M, coercivity H_c, exchange bias He (field-cooled in 55 kOe) and the Neel temperature TN (where He goes to zero) were measured. The TOAB-capped NP have higher magnitudes of Ms (the weak ferromagnetic component of M) and lower He values, confirming the 1/Ms variation of He observed in uncapped CuO-NP for size < 16 nm. The reasons for the larger Ms in the capped vs. uncapped CuO-NP are now under investigation. TN decreases with the decrease in the particle size, as also observed for the uncapped CuO-NP. Supported in part by U.S. DOE (contract DE-FC26-99FT40540). [1]. K. Borgohain et al, Phys. Rev. B61, 11093 (2000). [2]. A. Punnoose and M. S. Seehra, preceding abstract. [3]. Punnoose, Magnone, Seehra & Bonevich, Phys. Rev. B64, 174420 (2001).

  3. Eddy current effects in the magnetization dynamics of ferromagnetic metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Denisov, S. I.; Lyutyy, T. V.; Pedchenko, B. O.; Babych, H. V.

    2014-07-01

    We develop an analytical model for describing the magnetization dynamics in ferromagnetic metal nanoparticles, which is based on the coupled system of the Landau-Lifshitz-Gilbert (LLG) and Maxwell equations. By solving Maxwell's equations in the quasi-static approximation and finding the magnetic field of eddy currents, we derive the closed LLG equation for the magnetization that fully accounts for the effects of conductivity. We analyze the difference between the LLG equations in metallic and dielectric nanoparticles and show that these effects can strongly influence the magnetization dynamics. As an example illustrating the importance of eddy currents, the phenomenon of precessional switching of magnetization is considered.

  4. Magnetic nanoparticle effects on the red blood cells

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

  5. Superparamagnetic nanoparticle quantification using a giant magnetoresistive sensor and permanent magnets

    NASA Astrophysics Data System (ADS)

    Park, Jongwon

    2015-09-01

    Magnetic nanoparticles are used in various biological applications such as magnetic resonance imaging (MRI), biological separation, drug delivery or as biomarker. In the case of biomarker, the magnetic particle and a measurand are combined via biological reactions and then detected by magnetic field sensors for a qualitative or quantitative measurement. In the present work, we introduce a commercially available giant magnetoresistive (GMR) sensor for the quantitative measurement of superparamagnetic nanoparticles, which were injected into a glass capillary tube. A pair of permanent magnets standing diagonally opposite to each other was utilized to provide vertical and horizontal magnetic fields for particle magnetization and sensor bias, respectively. In addition, the permanent magnets solved the uniformity problem of generated magnetic fields in previous biomarker detection systems. Using the proposed measurement setup, an output signal change of 0.407 V was achieved for a 1 ?g change in the magnetic particle mass. The detection limit was 43.5 ng.

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

    PubMed Central

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

    2012-01-01

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

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

    PubMed Central

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

    2014-01-01

    Molecular imaging allows clinicians to visualize the progression of tumours and obtain relevant information for patient diagnosis and treatment1. Owing to their intrinsic optical, electrical and magnetic properties, nanoparticles are promising contrast agents for imaging dynamic molecular and cellular processes such as protein-protein interactions, enzyme activity or gene expression2. Until now, nanoparticles have been engineered with targeting ligands such as antibodies and peptides to improve tumour specificity and uptake. However, excessive loading of ligands can reduce the targeting capabilities of the ligand3,4,5 and reduce the ability of the nanoparticle to bind to a finite number of receptors on cells6. Increasing the number of nanoparticles delivered to cells by each targeting molecule would lead to higher signal-to-noise ratios and improve image contrast. Here, we show that M13 filamentous bacteriophage can be used as a scaffold to display targeting ligands and multiple nanoparticles for magnetic resonance imaging of cancer cells and tumours in mice. Monodisperse iron oxide magnetic nanoparticles assemble along the M13 coat, and its distal end is engineered to display a peptide that targets SPARC glycoprotein, which is overexpressed in various cancers. Compared with nanoparticles that are directly functionalized with targeting peptides, our approach improves contrast because each SPARC-targeting molecule delivers a large number of nanoparticles into the cells. Moreover, the targeting ligand and nanoparticles could be easily exchanged for others, making this platform attractive for in vivo high-throughput screening and molecular detection. PMID:22983492

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  9. Engineered magnetic hybrid nanoparticles with enhanced relaxivity for tumor imaging.

    PubMed

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

    2013-10-01

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

  10. Magnetic lipid nanoparticles loading doxorubicin for intracellular delivery: Preparation and characteristics

    Microsoft Academic Search

    Xiao-Ying Ying; Yong-Zhong Du; Ling-Hong Hong; Hong Yuan; Fu-Qiang Hu

    2011-01-01

    Tumor intracellular delivery is an effective route for targeting chemotherapy to enhance the curative effect and minimize the side effect of a drug. In this study, the magnetic lipid nanoparticles with an uptake ability by tumor cells were prepared dispersing ferroso-ferric oxide nanoparticles in aqueous phase using oleic acid (OA) as a dispersant, and following the solvent dispersion of lipid

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

    PubMed

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

    2009-11-18

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

  12. Motility of CoFe2O4 nanoparticle-labelled microtubules in magnetic fields

    E-print Network

    Hancock, William O.

    Motility of CoFe2O4 nanoparticle-labelled microtubules in magnetic fields B.M. Hutchins, M. Platt is investigated both with and without applied magnetic fields. Microtubule gliding speed decreased of a magnetic field, however, the presence of a field did not significantly affect gliding speed or direction

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

    E-print Network

    Abes, Jeff I., 1975-

    2003-01-01

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

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

    PubMed Central

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

    2012-01-01

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

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

    PubMed

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

    2011-09-16

    The graphite encapsulation of metal alloy magnetic nanoparticles has attracted attention for biological applications because of the high magnetization of the encapsulated particles. However, most of the synthetic methods have limitations in terms of scalability and economics because of the demanding synthetic conditions and low yields. Here, we show that well controlled graphite-encapsulated FeCo core-shell nanoparticles can be synthesized by a hydrothermal method, simply by mixing Fe/Co with sucrose as a carbon source. Various Fe/Co metal ratios were used to determine the compositional dependence of the saturation magnetization and relaxivity coefficient. Transmission electron microscopy indicated that the particle sizes were 7 nm. In order to test the capability of graphite-encapsulated FeCo nanoparticles as magnetic resonance imaging (MRI) contrast agents, these nanoparticles were solubilized in water by the nonspecific physical adsorption of sodium dodecylbenzene sulfonate. PMID:21852740

  16. Growth of Fe-Pt Magnetic Nanoparticles on Silica Particles Modified with Organic Molecules

    NASA Astrophysics Data System (ADS)

    Kitamoto, Yoshitaka; Fuchigami, Teruaki; Namiki, Yoshihisa

    2013-11-01

    In the present paper, we describe the formation of an assembly composed of Fe-Pt magnetic nanoparticles on a template particle. The assembly is composed of a magnetic nanoshell for core/shell particles or hollow particles for application in nanomedicine devices. For this purpose, magnetic nanoparticles should be densely accumulated or deposited on template particles, Fe-Pt nanoparticles completely cover silica template particles by modifying them with a polymer such as poly(diallyldimethylammonium chloride) (PDDA), polyethyleneimine (PEI), or poly(N-vinyl-2-pyrrolidone) (PVP) followed by the polyol reduction of Fe and Pt compounds. Studies of their morphological, crystallographic, and magnetic properties reveal that Fe-Pt nanoparticles are selectively grown on the polymer-modified silica template particles; the polymer probably supplies nucleation sites for the formation of such nanoparticles. The species of polymer used strongly affects crystallographic and magnetic properties of the nanoparticles, particularly, the atomic ordering of Fe-Pt nanoparticles formed on silica template particles.

  17. Cellular uptake of magnetic nanoparticle is mediated through energy-dependent endocytosis in A549 cells

    PubMed Central

    Kim, Jun-Sung; Yoon, Tae-Jong; Yu, Kyeong-Nam; Noh, Mi Suk; Woo, Minah; Kim, Byung-Geol; Lee, Kee-Ho; Sohn, Byung-Hyuk; Park, Seung-Bum

    2006-01-01

    Biocompatible silica-overcoated magnetic nanoparticles containing an organic fluorescence dye, rhodamine B isothiocyanate (RITC), within a silica shell [50 nm size, MNP@SiO2(RITC)s] were synthesized. For future application of the MNP@SiO2(RITC)s into diverse areas of research such as drug or gene delivery, bioimaging, and biosensors, detailed information of the cellular uptake process of the nanoparticles is essential. Thus, this study was performed to elucidate the precise mechanism by which the lung cancer cells uptake the magnetic nanoparticles. Lung cells were chosen for this study because inhalation is the most likely route of exposure and lung cancer cells were also found to uptake magnetic nanoparticles rapidly in preliminary experiments. The lung cells were pretreated with different metabolic inhibitors. Our results revealed that low temperature disturbed the uptake of magnetic nanoparticles into the cells. Metabolic inhibitors also prevented the delivery of the materials into cells. Use of TEM clearly demonstrated that uptake of the nanoparticles was mediated through endosomes. Taken together, our results demonstrate that magnetic nanoparticles can be internalized into the cells through an energy-dependent endosomal-lysosomal mechanism. PMID:17106221

  18. Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

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

    PubMed

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

    2014-06-01

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

  20. Pulsed field probe of real time magnetization dynamics in magnetic nanoparticle systems

    NASA Astrophysics Data System (ADS)

    Foulkes, T.; Syed, M.; Taplin, T.

    2015-05-01

    Magnetic nanoparticles (MNPs) are extensively used in biotechnology. These applications rely on magnetic properties that are a keen function of MNP size, distribution, and shape. Various magneto-optical techniques, including Faraday Rotation (FR), Cotton-Mouton Effect, etc., have been employed to characterize magnetic properties of MNPs. Generally, these measurements employ AC or DC fields. In this work, we describe the results from a FR setup that uses pulsed magnetic fields and an analysis technique that makes use of the entire pulse shape to investigate size distribution and shape anisotropy. The setup employs a light source, polarizing components, and a detector that are used to measure the rotation of light from a sample that is subjected to a pulsed magnetic field. This magnetic field "snapshot" is recorded alongside the intensity pulse of the sample's response. This side by side comparison yields useful information about the real time magnetization dynamics of the system being probed. The setup is highly flexible with variable control of pulse length and peak magnitude. Examining the raw data for the response of bare Fe3O4 and hybrid Au and Fe3O4 nanorods reveals interesting information about Brownian relaxation and the hydrodynamic size of these nanorods. This analysis exploits the self-referencing nature of this measurement to highlight the impact of an applied field on creating a field induced transparency for a longitudinal measurement. Possible sources for this behavior include shape anisotropy and field assisted aggregate formation.

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

    E-print Network

    Ivanova, Viara; Hristov, Jordan

    2011-01-01

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

  2. Formation and properties of magnetic chains for 100 nm nanoparticles used in separations of molecules and cells

    PubMed Central

    Wilson, Robert J.; Hu, Wei; Fu, Cheryl Wong Po; Koh, Ai Leen; Gaster, Richard S.; Earhart, Christopher M.; Fu, Aihua; Heilshorn, Sarah C.; Sinclair, Robert; Wang, Shan X.

    2009-01-01

    Optical observations of 100 nm metallic magnetic nanoparticles are used to study their magnetic field induced self assembly. Chains with lengths of tens of microns are observed to form within minutes at nanoparticle concentrations of 1010 per mL. Chain rotation and magnetophoresis are readily observed, and SEM reveals that long chains are not simple single particle filaments. Similar chains are detected for several 100 nm commercial bio-separation nanoparticles. We demonstrate the staged magnetic condensation of different types of nanoparticles into composite structures and show that magnetic chains bind to immunomagnetically labeled cells, serving as temporary handles which allow novel magnetic cell manipulations. PMID:20161001

  3. Biocompatibility of hydrophilic silica-coated CdTe quantum dots and magnetic nanoparticles

    Microsoft Academic Search

    Jing Ruan; Kan Wang; Hua Song; Xin Xu; Jiajia Ji; Daxiang Cui

    2011-01-01

    Fluorescent magnetic nanoparticles exhibit great application prospects in biomedical engineering. Herein, we reported the\\u000a effects of hydrophilic silica-coated CdTe quantum dots and magnetic nanoparticles (FMNPs) on human embryonic kidney 293 (HEK293)\\u000a cells and mice with the aim of investigating their biocompatibility. FMNPs with 150 nm in diameter were prepared, and characterized\\u000a by high-resolution transmission electron microscopy and photoluminescence (PL) spectra

  4. Influence of surface spins on the magnetization of fine maghemite nanoparticles

    SciTech Connect

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

    2013-12-16

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

  5. Low-temperature magnetic property of polymer encapsulated gold nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2009-10-01

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

  6. Self assembly of magnetic nanoparticles at silicon surfaces.

    PubMed

    Theis-Bröhl, Katharina; Gutfreund, Philipp; Vorobiev, Alexei; Wolff, Max; Toperverg, Boris P; Dura, Joseph A; Borchers, Julie A

    2015-06-01

    Neutron reflectometry was used to study the assembly of magnetite nanoparticles in a water-based ferrofluid close to a silicon surface. Under three conditions, static, under shear and with a magnetic field, the depth profile is extracted. The particles have an average diameter of 11 nm and a volume density of 5% in a D2O-H2O mixture. They are surrounded by a 4 nm thick bilayer of carboxylic acid for steric repulsion. The reflectivity data were fitted to a model using a least square routine based on the Parratt formalism. From the scattering length density depth profiles the following behavior is concluded: the fits indicate that excess carboxylic acid covers the silicon surface and almost eliminates the water in the densely packed wetting layer that forms close to the silicon surface. Under constant shear the wetting layer persists but a depletion layer forms between the wetting layer and the moving ferrofluid. Once the flow is stopped, the wetting layer becomes more pronounced with dense packing and is accompanied by a looser packed second layer. In the case of an applied magnetic field the prolate particles experience a torque and align with their long axes along the silicon surface which leads to a higher particle density. PMID:25971712

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

    NASA Astrophysics Data System (ADS)

    Zhang, Minghui; Brazel, Christopher

    2011-11-01

    This study investigated how the percent capture of magnetic nanoparticles in a simulated vessel varies with physical variables. Magnetic nanoparticles (MNPs) can used as part of therapeutic or diagnostic materials for cancer patients. By capturing these devices with a magnetic field, the particles can be concentrated in an area of diseased tissue. In this study, flow of nanoparticles in simulated blood vessels was used to determine the affect of applying an external magnetic field. This study used maghemite nanoparticles as the MNPs and either water or Fetal Bovine Serum as the carrier fluid. A UV-Vis collected capture data. The percent capture of MNPs was positively influenced by five physical variables: larger vessel diameters, lower linear flow velocity, higher magnetic field strength, better dispersion, lower MNP concentration, and lower protein content in fluid. Free MNPs were also compared to micelles, with the free particles having more successful magnetic capture. Four factors contributed to these trends: the strength of the magnetic field's influence on the MNPs, the MNPs' interactions with other particles and the fluid, the momentum of the nanoparticles, and magnetic mass to total mass ratio of the flowing particles. Funded by NSF REU Site #1062611.

  8. Study of magnetic properties of ZnO nanoparticles codoped with Co and Cu

    Microsoft Academic Search

    Haitao Xu; Qidong Zhao; Hua Yang; Yan Chen

    2009-01-01

    Here, we report on systematic studies of the magnetic properties of Co and Cu codoped ZnO nanoparticles prepared by sol–gel\\u000a technique. The effect of hydrogenation and shape on the magnetic properties of Zn0.93Co0.05Cu0.02O nanoparticles is presented. The Zn0.93Co0.05Cu0.02O nanoparticles and well-aligned Zn0.93Co0.05Cu0.02O nanorod array display ferromagnetic behavior at room temperature. Our results demonstrate the influence of shape and hydrogenation\\u000a on

  9. Highly magnetic iron carbide nanoparticles as effective T(2) contrast agents.

    PubMed

    Huang, Guoming; Hu, Juan; Zhang, Hui; Zhou, Zijian; Chi, Xiaoqin; Gao, Jinhao

    2014-01-21

    This paper reports that iron carbide nanoparticles with high air-stability and strong saturation magnetization can serve as effective T2 contrast agents for magnetic resonance imaging. Fe5C2 nanoparticles (~20 nm in diameter) exhibit strong contrast enhancement with an r2 value of 283.2 mM(-1) S(-1), which is about twice as high as that of spherical Fe3O4 nanoparticles (~140.9 mM(-1) S(-1)). In vivo experiments demonstrate that Fe5C2 nanoparticles are able to produce much more significant MRI contrast enhancement than conventional Fe3O4 nanoparticles in living subjects, which holds great promise in biomedical applications. PMID:24287667

  10. Bacterial inactivation using silver-coated magnetic nanoparticles as functional antimicrobial agents

    PubMed Central

    Wang, Lingyan; Luo, Jin; Shan, Shiyao; Crew, Elizabeth; Yin, Jun; Zhong, Chuan-Jian; Wallek, Brandi; Wong, Season

    2011-01-01

    The ability for silver nanoparticles to function as an antibacterial agent while being separable from the target fluids is important for bacterial inactivation in biological fluids. This report describes the analysis of the antimicrobial activities of silver-coated magnetic nanoparticles synthesized by wet chemical methods. The bacterial inactivation of several types of bacteria was analyzed, including Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) and Gram-negative bacteria (Pseudomonas aeruginosa, Enterobacter cloacae, and Escherichia coli). The results have demonstrated the viability of the silver-coated magnetic nanoparticles for achieving effective bacterial inactivation efficiency comparable to and better than silver nanoparticles conventionally used. The bacteria inactivation efficiency of our MZF@Ag nanoparticles were also determined for blood platelets samples, demonstrating the potential of utilization in inactivating bacterial growth in platelets prior to transfusion to ensure blood product safety, which also has important implications for enabling the capability of effective separation, delivery and targeting of the antibacterial agents. PMID:21999710

  11. Sonochemical Synthesis and Magnetic Imaging of Hollow-Shell Iron-Platinum Nanoparticles

    NASA Astrophysics Data System (ADS)

    Baker, Remmi; Barnes, Paris; Martell, Eric

    2015-04-01

    As science has continued to evolve, scientists have been diving deeper and deeper, researching and analyzing the tiniest of objects. Interestingly, materials such as gold, silver, iron, and platinum behave differently on the nanoscale than the macroscale. Discrepancies between the behaviors of macro- and nanoparticles of the same substance are not well understood, which has led scientists to pursue the question as to why nanoparticles behave differently. Further research into the fabrication of hollow-shell iron-platinum nanoparticles and their unique properties may lead to real-world applications. Iron-platinum (FePt) nanoparticles are recognized for their unique magnetic properties; however, these properties have largely not been researched. FePt samples were prepared using sonochemical techniques. We report on the magnetic force microscopy imaging for self-assembled hollow-shell FePt nanoparticles, and relate our findings to the physical characteristics of the hollow-shell FePt nanoparticles. Additionally, we investigate the magnetic properties for FePt nanoparticles by analyzing the role of the electrons and their interactions occurring within the magnetic domain.

  12. Magnetic properties of monodispersed Ni/NiO core-shell nanoparticles.

    PubMed

    Seto, Takafumi; Akinaga, Hiroyuki; Takano, Fumiyoshi; Koga, Kenji; Orii, Takaaki; Hirasawa, Makoto

    2005-07-21

    We have recently developed a method to fabricate monodispersed Ni/NiO core-shell nanoparticles by pulsed laser ablation. In this report, the size-dependent magnetic properties of monodispersed Ni/NiO core-shell nanoparticles were investigated. These nanoparticles were formed in two steps. The first was to fabricate a series of monodispersed Ni nanoparticles of 5 to 20 nm in diameter using a combination of laser ablation and size classification by a low-pressure differential mobility analyzer (DMA). The second step was to oxidize the surfaces of the Ni particles in situ to form core-shell structures. A superconducting quantum interference device (SQUID) magnetometer was used to measure the magnetic properties of nanostructured films prepared by depositing the nanoparticles at room temperature. Ferromagnetism was observed in the magnetic hysteresis loop of the nanostructured films composed of core-shell nanoparticles with core diameters smaller than the superparamagnetic limit, which suggests the spin of Ni core was weakly exchange coupled with antiferromagnetic NiO shell. In contrast, smaller nanoparticles with core diameters of 3.0 nm exhibited superparamagnetism. The drastic change in the hysteresis loops between field-deposited and zero-field-deposited samples was attributable to the strong anisotropy that developed during the magnetic-field-assisted nanostructuring process. PMID:16852675

  13. Large-scale production of magnetic nanoparticles using bacterial fermentation.

    PubMed

    Moon, Ji-Won; Rawn, Claudia J; Rondinone, Adam J; Love, Lonnie J; Roh, Yul; Everett, S Michelle; Lauf, Robert J; Phelps, Tommy J

    2010-10-01

    Production of both nano-sized particles of crystalline pure phase magnetite and magnetite substituted with Co, Ni, Cr, Mn, Zn or the rare earths for some of the Fe has been demonstrated using microbial processes. This microbial production of magnetic nanoparticles can be achieved in large quantities and at low cost. In these experiments, over 1 kg (wet weight) of Zn-substituted magnetite (nominal composition of Zn(0.6)Fe(2.4)O4) was recovered from 30 l fermentations. Transmission electron microscopy (TEM) was used to confirm that the extracellular magnetites exhibited good mono-dispersity. TEM results also showed a highly reproducible particle size and corroborated average crystallite size (ACS) of 13.1 ± 0.8 nm determined through X-ray diffraction (N = 7) at a 99% confidence level. Based on scale-up experiments performed using a 35-l reactor, the increase in ACS reproducibility may be attributed to a combination of factors including an increase of electron donor input, availability of divalent substitution metal ions and fewer ferrous ions in the case of substituted magnetite, and increased reactor volume overcoming differences in each batch. Commercial nanometer sized magnetite (25-50 nm) may cost $500/kg. However, microbial processes are potentially capable of producing 5-90 nm pure or substituted magnetites at a fraction of the cost of traditional chemical synthesis. While there are numerous approaches for the synthesis of nanoparticles, bacterial fermentation of magnetite or metal-substituted magnetite may represent an advantageous manufacturing technology with respect to yield, reproducibility and scalable synthesis with low costs at low energy input. PMID:20544257

  14. Intracellular performance of tailored nanoparticle tracers in magnetic particle imaging

    SciTech Connect

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

    2014-05-07

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

  15. Synthesis and characterization of poly(divinylbenzene)-coated magnetic iron oxide nanoparticles as precursor for the formation of air-stable carbon-coated iron crystalline nanoparticles.

    PubMed

    Boguslavsky, Yonit; Margel, Shlomo

    2008-01-01

    Maghemite (gamma-Fe2O3) nanoparticles of 15 +/- 3 nm diameter were prepared by nucleation of gelatin/iron oxide followed by growth of gamma-Fe2O3 films onto these nuclei. The gamma-Fe2O3 nanoparticles were coated with polydivinylbenzene (PDVB) by emulsion polymerization of divinylbenzene (DVB) in an aqueous continuous phase containing the gamma-Fe2O3 nanoparticles. The PDVB-coated gamma-Fe2O3 nanoparticles, dispersed in water, were separated from homo-PDVB nanoparticles using the high gradient magnetic field (HGMF) technique. The influence of DVB concentration on the amount of PDVB coating, on the size and size distribution of the coated gamma-Fe2O3 nanoparticles and on their magnetic properties, has been investigated. Air-stable carbon-coated iron (alpha-Fe/C) crystalline nanoparticles of 41 +/- 12 nm diameter have been prepared by annealing the PDVB-coated gamma-Fe2O3 nanoparticles at 1050 degrees C in an inert atmosphere. These nanoparticles exhibit high saturation magnetization value (83 emu g(-1)) and excellent resistance to oxidation. Characterization of the PDVB-coated gamma-Fe2O3 and of the alpha-Fe/C nanoparticles has been accomplished by TEM, HRTEM, DLS, FTIR, XRD, thermal analysis, zeta-potential, and magnetic measurements. PMID:17927999

  16. Preparing a magnetically responsive single-wall carbon nanohorn colloid by anchoring magnetite nanoparticles.

    PubMed

    Utsumi, Shigenori; Urita, Koki; Kanoh, Hirofumi; Yudasaka, Masako; Suenaga, Kazutomo; Iijima, Sumio; Kaneko, Katsumi

    2006-04-13

    A single-wall carbon nanohorn (SWNH) colloid was made to be magnetically responsive by anchoring magnetite nanoparticles prepared by the homogeneous mixing of FeCl(2)-FeCl(3) and NaOH solutions. Transmission electron microscopy observation showed the high dispersion of magnetite particles of 2-9 nm on the surface of the SWNH colloid, coinciding with the broad X-ray diffraction peaks of the magnetites. The magnetization measurements showed that the magnetite nanoparticles-anchored SWNH (mag-SWNH) colloid has the hybrid property of ferrimagnetism and superparamagnetism. It was demonstrated that mag-SWNH colloid dispersed in water by sonication responded to an external magnetic field, gathering toward a magnet. N(2) adsorption experiments showed the high nanoporosity of mag-SWNHs and that magnetite nanoparticles were preferably anchored at "nanowindow" sites and the entrance sites of interstitial pores. This magnetically responsive SWNH colloid should contribute to the field of drug delivery. PMID:16599481

  17. Structure, morphology and magnetic properties of Fe Au core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Pana, O.; Teodorescu, C. M.; Chauvet, O.; Payen, C.; Macovei, D.; Turcu, R.; Soran, M. L.; Aldea, N.; Barbu, L.

    2007-09-01

    The aim of the present work is the investigation of the core-shell Fe@Au nanoparticles obtained by the inverse micelles method. Also hybrid structures between Fe@Au nanoparticles and the well-known conducting polymer polypyrrole (PPY) were obtained and investigated. The properties of the composites were investigated by TEM, HRTEM, X-ray diffraction (XRD), X-ray Photoelectron spectroscopy (XPS) and magnetization measurements. The TEM, HRTEM measurements show that two categories of core-shell nanoparticles with mean diameters of 5 nm and 25 nm, respectively, are formed. The XPS investigations of the core-shell Fe@Au nanoparticles indicate that besides Fe 0 inside the cores, small amounts of Fe II,III, located onto the gold surface ,were also formed during the samples preparation. The magnetization of the investigated nanocomposites measured versus increasing and decreasing magnetic field shows no hysteresis loop, this behavior being consistent with a superparamagnetic behavior. The behavior of the SQUID magnetization vs. temperature under field cooled (FC) and zero field cooled (ZFC) at 0.1 T magnetic field for Fe@Au nanoparticles confirmed the existence of superparamagnetism. The superparamagnetic model was used to fit the experimental magnetization vs. applied magnetic field as it was measured by SQUID up to 5 T.

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

    NASA Astrophysics Data System (ADS)

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

    2009-07-01

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

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

    SciTech Connect

    Kumari, Monika; Hirt, Ann M., E-mail: ann.hirt@erdw.ethz.ch [Department of Earth Sciences, Institute of Geophysics, ETH-Zurich, Sonneggstrasse 5, CH-8092 Zurich (Switzerland); Widdrat, Marc; Faivre, Damien [Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Golm, D-14424 Potsdam (Germany); Tompa, Éva; Pósfai, Mihály [Department of Earth and Environmental Sciences, University of Pannonia, Egyetem u. 10, H-8200 Veszprém (Hungary); Uebe, Rene; Schüler, Dirk [Department Biologie I, LMU Munich, Großhaderner Str. 2, D-82152 Martinsried (Germany)

    2014-09-28

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-10-01

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

  1. Magnetism and spin dynamics of novel encapsulated iron oxide superparamagnetic nanoparticles.

    PubMed

    Arosio, Paolo; Baldi, Giovanni; Chiellini, Federica; Corti, Maurizio; Dessy, Alberto; Galinetto, Pietro; Gazzarri, Matteo; Grandi, Marco Simone; Innocenti, Claudia; Lascialfari, Alessandro; Lorenzi, Giada; Orsini, Francesco; Piras, Anna Maria; Ravagli, Costanza; Sangregorio, Claudio

    2013-07-28

    Encapsulated Fe3O4 nanoparticles of average diameters d = 12 nm are obtained by coprecipitation, in the presence of 2-methoxyethanol hemiester of poly(maleic anhydride-alt-butyl vinyl ether) 5% grafted with poly(ethylene glycol) (VP-MAG nanoparticles). A complete characterization of nude and encapsulated nanoparticles through structural techniques (namely XRD, TEM, SEM), Raman spectroscopy and magnetic measurements has been performed. These nanoparticles compared with commercial compounds (ENDOREM®) present superparamagnetic behavior and nuclear relaxivities that make them promising as magnetic resonance imaging (MRI) contrast agents (CAs). We found that our nanostructures exhibit r2 relaxivity higher than those of commercial CAs over the whole frequency range. The MRI efficiency of our samples was related to their microstructural and magnetic properties. PMID:23736525

  2. Mössbauer spectroscopy studies of carbon-encapsulated magnetic nanoparticles obtained by different routes

    Microsoft Academic Search

    M. Bystrzejewski; A. Grabias; J. Borysiuk; A. Huczko; H. Lange

    2008-01-01

    Carbon-encapsulated magnetic nanoparticles (CEMNPs) are nanomaterials with a core-shell structure. Their intrinsic properties result both from the unique nature of the encapsulated magnetic phases and the high chemical stability of the external carbon shells. CEMNPs may find many prospective applications, e.g., in magnetic data storage, catalysis, xerography, magnetic resonance imaging, and in biomedical applications. Herein, we present detailed structural studies

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    It is important to increase operating frequency of power electronics for miniaturization of components. Magnetic materials are used as inductor cores to increase inductance proportional to their magnetic permeability. However, traditional magnetic materials are not used at high frequency (>100MHz) because of large hysteresis and eddy current loss. Superparamagnetic nanoparticles are good candidates to resolve these problems because they have zero hysteresis loss. In addition, eddy currents can be reduced due to their high electric resistivity originating from the organic ligands on the surface. Magnetic nanoparticles such as NiFe2O4, Ni1-xZnxFe2O4, MnFe3O4 and ZnFe2O4 have been synthesized via high temperature thermal decomposition method and can be tuned to desired size, shape and chemical composition. To understand structural and magnetic properties of nanoparticles, the nanoparticles have been characterized by TEM, SQUID, PPMS, and Network Analyzer. UV-induced polymerization and pressing method have been implemented for film deposition. Finally, AC susceptibility of the nanoparticle film have been measured and discussed for low energy-loss applications. It is important to increase operating frequency of power electronics for miniaturization of components. Magnetic materials are used as inductor cores to increase inductance proportional to their magnetic permeability. However, traditional magnetic materials are not used at high frequency (>100MHz) because of large hysteresis and eddy current loss. Superparamagnetic nanoparticles are good candidates to resolve these problems because they have zero hysteresis loss. In addition, eddy currents can be reduced due to their high electric resistivity originating from the organic ligands on the surface. Magnetic nanoparticles such as NiFe2O4, Ni1-xZnxFe2O4, MnFe3O4 and ZnFe2O4 have been synthesized via high temperature thermal decomposition method and can be tuned to desired size, shape and chemical composition. To understand structural and magnetic properties of nanoparticles, the nanoparticles have been characterized by TEM, SQUID, PPMS, and Network Analyzer. UV-induced polymerization and pressing method have been implemented for film deposition. Finally, AC susceptibility of the nanoparticle film have been measured and discussed for low energy-loss applications. This work is supported by the Advanced Research Projects Agency - Energy (ARPA-E) program grant number DE-AR0000123.

  4. Magnetic resonance imaging of mesenchymal stem cells homing to pulmonary metastases using biocompatible magnetic nanoparticles

    PubMed Central

    Loebinger, Michael R; Kyrtatos, Panagiotis G; Turmaine, Mark; Price, Anthony N; Pankhurst, Quentin; Lythgoe, Mark F; Janes, Sam M

    2010-01-01

    The ability of mesenchymal stem cells (MSCs) to specifically home to tumors has suggested their potential use as a delivery vehicle for cancer therapeutics. MSC integration into tumors has been demonstrated in animal models using histopathological techniques after animal sacrifice. Tracking the delivery and engraftment of MSCs into human tumors will need in vivo imaging techniques. We hypothesized that labeling MSCs with iron oxide nanoparticles would enable in vivo tracking with magnetic resonance imaging (MRI). Human MSCs were labeled in vitro with superparamagnetic iron oxide nanoparticles, with no effect on differentiation potential, proliferation, survival or migration of the cells. In initial experiments we demonstrated that as few as 1000 MSCs carrying iron oxide nanoparticles can be detected by MRI one month after their coinjection with breast cancer cells which formed sub-cutaneous tumors. Subsequently we show that intravenously injected iron-labeled MSCs could be tracked in vivo to multiple lung metastases using MRI, observations that were confirmed histologically. This is the first study to utilize MRI to track MSCs to lung metastases in vivo. This technique has the potential to demonstrate MSC integration into human tumors, allowing early phase clinical studies examining MSC homing in patients with metastatic tumors. PMID:19920196

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

    PubMed Central

    2012-01-01

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

  6. Ex vivo magnetofection with magnetic nanoparticles: a novel platform for nonviral tissue engineering.

    PubMed

    Yang, Shieh-Yueh; Sun, Jui-Sheng; Liu, Cheng-Heng; Tsuang, Yang-Hwei; Chen, Li-Ting; Hong, Chin-Yih; Yang, Hong-Chang; Horng, Herng-Er

    2008-03-01

    Several methods have been described to introduce DNA expression vectors into mammalian cells both in vitro and in vivo. Each system has benefits and limitations, and to date there is still no ideal method for gene transfer. In this study, we introduced a novel method of gene transfer by using Fe3O4 nanoparticles. The magnetic nanoparticles composed of Fe3O4, and the transfected genes used are Lac Z and enhanced green fluorescence protein gene (EGFG). Four different groups of preparations included in this study were homemade liposome-enveloped EGFP-DNA/Fe3O4, homemade liposome EGFP-DNA gene without magnetic Fe3O4 nanoparticles, lipofectamine 2000-enveloped EGFP-DNA, and EGFP-DNA gene only. Mice osteoblast and He99 lung cancer cell line were used as host cells for gene transfection. The time-dependent EGFP gene expression was monitored and analyzed. The results showed that the diameter of the complex was less than 100 nm. There was no cytotoxicity observed at any of the magnetic Fe3O4 nanoparticle concentrations tested. In the presence of magnetic field, the liposome-enveloped EGFP-DNA/Fe3O4 complex exhibited a much higher efficiency for transfecting EGFP-DNA into osteoblast cells under external magnetic fields. The gene can be transfected into cells with an aid of magnetic vectors and magnetic force. Under a gradient magnetic field, the efficiency of magnetofection is enhanced as compared to that without magnetic field. PMID:18201284

  7. Synthesis and characterization of magnetic palygorskite nanoparticles and their application on methylene blue remotion from water

    NASA Astrophysics Data System (ADS)

    Middea, Antonieta; Spinelli, Luciana S.; Souza, Fernando G.; Neumann, Reiner; Gomes, Otavio da F. M.; Fernandes, Thais L. A. P.; de Lima, Luiz C.; Barthem, Vitoria M. T. S.; de Carvalho, Fernanda V.

    2015-08-01

    Recently there has been considerable interest in magnetic sorbents materials, which is added excellent capabilities such as sorption and magnetic response to an applied field. Accordingly, palygorskite nanoparticles were covered by magnetite using a co-precipitation technique and characterized by: X-ray fluorescence (XRF), X-ray diffraction (XRD), surface analysing and scanning electron microscopy (SEM) with element analysis and mapping, particle size, pore surface area (BET), density, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and zeta potential. Additionally, magnetic properties were studied by SQUID magnetometer, magnetic force microscopy (MFM) and also using a simple experimental setup. Magnetic nanoparticles produced had average diameters in a nanometric range. The amount of iron present in the nanoparticles increased by six times after the magnetization and a superparamagnetic behavior was exhibited with high saturation magnetization, from 4.0 × 10-4 Am2/kg to about 20 Am2/kg. A weight loss was also observed around 277 °C-339 °C by TGA, indicating a structural change from magnetite to maghemite, which confirms the magnetization of palygorskite. Batch adsorption experiments were carried out for the removal of methylene blue cationic dye from aqueous solution using pure and covered by magnetite palygorskite nanoparticles as adsorbents. Furthermore, about 90% of methylene blue was removed within 3 min using magnetized palygorskite.

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

    NASA Astrophysics Data System (ADS)

    Humphrey, Emma Margaret

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

  9. The effect of the external magnetic field on the thermal relaxation of magnetization in systems of aligned nanoparticles

    NASA Astrophysics Data System (ADS)

    Caizer, C.

    2005-03-01

    The dynamics of magnetic relaxation in a system of isolated ferrimagnetic nanoparticles depends on the ratio between the magnetic relaxation time (?) and the measurement time (tm), which is usually considered to be equal to the period (TH) of the external alternating magnetic field (tm = TH). When tm approaches ? (?magnetic moments cannot relax completely, thus leading to a deviation from the superparamagnetic behaviour (SPM), and a magnetic remanence of the system when the deviation is large. An external magnetic field (H) can significantly change the dynamics of the relaxation, especially when its amplitude (Hm) is high. This paper shows that there is a limit field (threshold field (Hp)) that depends on the anisotropy field of the nanoparticle, its magnetic volume and on the temperature; beyond this field, the magnetic moments cannot pass the potential barrier and they remain blocked. It will be shown that under these conditions the measurement time can no longer be considered to be tm = TH, but is a measurement time tmH< TH that in addition to TH will also depend on Hp and Hm. When the amplitude of the alternating magnetic field is lower than the value of the threshold field (Hm< Hp), the measurement time is reduced to the period of the magnetic field. The theory proposed for a system of aligned nanoparticles has been verified experimentally in the case of a ferrofluid-type system. The result obtained brings in important corrections for determining the magnetic volume of the nanoparticles or the magnetic anisotropy constant if the condition tm = tmH< TH is used when Hm is high (Hm> Hp), instead of tm = TH.

  10. Optical Imaging and Magnetic Field Targeting of Magnetic Nanoparticles in Tumors

    PubMed Central

    Foy, Susan P.; Manthe, Rachel L.; Foy, Steven T.; Dimitrijevic, Sanja; Krishnamurthy, Nishanth; Labhasetwar, Vinod

    2010-01-01

    To address efficacy issues of cancer diagnosis and chemotherapy, we have developed a magnetic nanoparticle (MNP) formulation with combined drug delivery and imaging properties that can potentially be used in image-guided drug therapy. Our MNP consists of an iron-oxide magnetic core coated with oleic acid (OA) and stabilized with an amphiphilic block copolymer. Previously, we reported that our MNP formulation can provide prolonged contrast for tumor magnetic resonance imaging and can be loaded with hydrophobic anticancer agents for sustained drug delivery. In this study, we developed MNPs with optical imaging properties using new near-infrared dyes to quantitatively determine their long-term biodistribution and tumor localization with and without an external magnetic field in mice with xenograft breast tumors. MNPs localized slowly in the tumor, reaching a peak 48 h post injection before slowly declining over the next 11 days. One-hour exposure of the tumor to a magnetic field further enhanced MNP localization to tumors. Our MNPs can be developed with combined drug delivery and multimodal imaging properties to improve cancer diagnosis, provide sustained treatment, and monitor therapeutic effects in tumors over time. PMID:20731413

  11. Visualization and quantification of magnetic nanoparticles into vesicular systems by combined atomic and magnetic force microscopy

    NASA Astrophysics Data System (ADS)

    Dong, C.; Corsetti, S.; Passeri, D.; Rossi, M.; Carafa, M.; Pantanella, F.; Rinaldi, F.; Ingallina, C.; Sorbo, A.; Marianecci, C.

    2015-06-01

    We report a phenomenological approach for the quantification of the diameter of magnetic nanoparticles (MNPs) incorporated in non-ionic surfactant vesicles (niosomes) using magnetic force microscopy (MFM). After a simple specimen preparation, i.e., by putting a drop of solution containing MNPs-loaded niosomes on flat substrates, topography and MFM phase images are collected. To attempt the quantification of the diameter of entrapped MNPs, the method is calibrated on the sole MNPs deposited on the same substrates by analyzing the MFM signal as a function of the MNP diameter (at fixed tip-sample distance) and of the tip-sample distance (for selected MNPs). After calibration, the effective diameter of the MNPs entrapped in some niosomes is quantitatively deduced from MFM images.

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

    Hydroxyapatite (HA) coated iron oxide (Fe3O4) magnetic nanoparticles have been shown to enhance osteoblast (bone forming cells) proliferation and osteoblast differentiation into calcium depositing cells (through increased secretion of alkaline phosphatase, collagen and calcium deposition) compared to control samples without nanoparticles. Such nanoparticles are, thus, very promising for numerous orthopedic applications including magnetically directed osteoporosis treatment. The objective of the current study was to elucidate the mechanisms of the aforementioned improved osteoblast responses in the presence of HA coated Fe3O4 nanoparticles. Results demonstrated large amounts of fibronectin (a protein known to increase osteoblast functions) adsorption on HA coated Fe3O4 nanoparticles. Specifically, fibronectin adsorption almost doubled when HA coated Fe3O4 nanoparticle concentrations increased from 12.5 to 100 ?g ml-1, and from 12.5 to 200 ?g ml-1, a four fold increase was observed. Results also showed greater osteoblast gene regulation (specifically, osteocalcin, type I collagen and cbfa-1) in the presence of HA coated Fe3O4 nanoparticles. Collectively, these results provide a mechanism for the observed enhanced osteoblast functions in the presence of HA coated iron oxide nanoparticles, allowing their further investigation for a number of orthopedic applications.

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

    PubMed

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

    2014-02-15

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

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

    PubMed

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

    2015-02-01

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

  15. Morphological effect of oscillating magnetic nanoparticles in killing tumor cells

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  16. Antiviral Properties of Silver Nanoparticles on a Magnetic Hybrid Colloid

    PubMed Central

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

    2014-01-01

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

  17. Spectroscopic AC susceptibility imaging (sASI) of magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

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

    SciTech Connect

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

    2009-10-15

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

  19. Polymer-assisted iron oxide magnetic nanoparticle immobilized keratinase.

    PubMed

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

    2009-06-01

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

  20. Application and reactivation of magnetic nanoparticles in Microcystis aeruginosa harvesting.

    PubMed

    Lin, Zhong; Xu, Yunfeng; Zhen, Zhen; Fu, Yu; Liu, Yueqiao; Li, Wenyan; Luo, Chunling; Ding, Aizhong; Zhang, Dayi

    2015-08-01

    This study developed a magnetic nanoparticles (MNPs) harvesting and reactivation technique for rapid cyanobacteria Microcystis aeruginosa separation. The harvesting of raw MNPs achieved high efficiency of 99.6% with the MNPs dosage of 0.58g MNPs/g dry-biomass, but gradually decreased to 59.1% when directly reused 5 times. With extra ultrasonic chloroform:methanol solvent treatment, the MNPs can be effectively reactivated for M. aeruginosa harvesting with 60% efficiency after 5 times reactivation and the separation efficiency kept above 93% with 0.20g MNPs/g dry-biomass dosage. The cyanobacteria-MNPs complex can be effectively disrupted by ultrasonic chloroform:methanol solvent treatment and the zeta potential was recovered for MNPs electrostatic attraction. The MNPs adsorption followed the Langmuir isotherm, and the maximum adsorption capacity and Langmuir constant was 3.74g dry-biomass/g and 311.64L/g respectively. This MNPs reactivation technique can achieve low energy separation and reduce MNPs consumption by 67%, providing potential engineering implementation for cyanobacterial biomass harvesting. PMID:25935387

  1. Stem Cells: Physical Stimuli-Induced Chondrogenic Differentiation of Mesenchymal Stem Cells Using Magnetic Nanoparticles (Adv. Healthcare Mater. 9/2015).

    PubMed

    Son, Boram; Kim, Hwan D; Kim, Minsoo; Kim, Jeong Ah; Lee, Jinkyu; Shin, Heungsoo; Hwang, Nathaniel S; Park, Tai Hyun

    2015-06-01

    On page 1339, N. S. Hwang, T. H. Park, and co-workers induce chondrogenic differentiation of mesenchymal stem cells by physical stimulation using magnetic nanoparticles. Magnetic nanoparticles isolated from magnetic bacteria are introduced into the mesenchymal stem cells. Then, the magnetic particle-incorporated mesenchymal stem cells are subjected to static magnetic field and/or magnet-derived shear stress. This magnetic nanoparticle-mediated physical stimulation can be used for cartilage tissue engineering. PMID:26109038

  2. Optimal Halbach Permanent Magnet Designs for Maximally Pulling and Pushing Nanoparticles.

    PubMed

    Sarwar, A; Nemirovski, A; Shapiro, B

    2012-03-01

    Optimization methods are presented to design Halbach arrays to maximize the forces applied on magnetic nanoparticles at deep tissue locations. In magnetic drug targeting, where magnets are used to focus therapeutic nanoparticles to disease locations, the sharp fall off of magnetic fields and forces with distances from magnets has limited the depth of targeting. Creating stronger forces at depth by optimally designed Halbach arrays would allow treatment of a wider class of patients, e.g. patients with deeper tumors. The presented optimization methods are based on semi-definite quadratic programming, yield provably globally optimal Halbach designs in 2 and 3-dimensions, for maximal pull or push magnetic forces (stronger pull forces can collect nano-particles against blood forces in deeper vessels; push forces can be used to inject particles into precise locations, e.g. into the inner ear). These Halbach designs, here tested in simulations of Maxwell's equations, significantly outperform benchmark magnets of the same size and strength. For example, a 3-dimensional 36 element 2000 cm(3) volume optimal Halbach design yields a ×5 greater force at a 10 cm depth compared to a uniformly magnetized magnet of the same size and strength. The designed arrays should be feasible to construct, as they have a similar strength (? 1 Tesla), size (? 2000 cm(3)), and number of elements (? 36) as previously demonstrated arrays, and retain good performance for reasonable manufacturing errors (element magnetization direction errors ? 5°), thus yielding practical designs to improve magnetic drug targeting treatment depths. PMID:23335834

  3. Optimal Halbach permanent magnet designs for maximally pulling and pushing nanoparticles

    NASA Astrophysics Data System (ADS)

    Sarwar, A.; Nemirovski, A.; Shapiro, B.

    2012-03-01

    Optimization methods are presented to design Halbach arrays to maximize the forces applied on magnetic nanoparticles at deep tissue locations. In magnetic drug targeting, where magnets are used to focus therapeutic nanoparticles to disease locations, the sharp fall off of magnetic fields and forces with distances from magnets has limited the depth of targeting. Creating stronger forces at a depth by optimally designed Halbach arrays would allow treatment of a wider class of patients, e.g. patients with deeper tumors. The presented optimization methods are based on semi-definite quadratic programming, yield provably globally optimal Halbach designs in 2 and 3-dimensions, for maximal pull or push magnetic forces (stronger pull forces can collect nanoparticles against blood forces in deeper vessels; push forces can be used to inject particles into precise locations, e.g. into the inner ear). These Halbach designs, here tested in simulations of Maxwell's equations, significantly outperform benchmark magnets of the same size and strength. For example, a 3-dimensional 36 element 2000 cm3 volume optimal Halbach design yields a 5× greater force at a 10 cm depth compared to a uniformly magnetized magnet of the same size and strength. The designed arrays should be feasible to construct, as they have a similar strength (?1 T), size (?2000 cm3), and number of elements (?36) as previously demonstrated arrays, and retain good performance for reasonable manufacturing errors (element magnetization direction errors ?5°), thus yielding practical designs to improve magnetic drug targeting treatment depths.

  4. Nanomechanical control of the activity of enzymes immobilized on single-domain magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Golovin, Yu. I.; Gribanovskii, S. L.; Klyachko, N. L.; Kabanov, A. V.

    2014-06-01

    Analytical and numerical methods are used to analyze the main regularities of deformation of biologically active molecules caused by the nonthermal effect of low-frequency magnetic field on single-domain magnetic nanoparticles to the surfaces of which the macromolecules are chemically bound.

  5. Synthesis and functionalization of magnetic nanoparticles with covalently bound electroactive compound doxorubicin

    Microsoft Academic Search

    Magdalena Brzozowska; Pawel Krysinski

    2009-01-01

    We report here on covalent functionalization of magnetic nanoparticle colloidal suspension (ferrofluid) with doxorubicin. Since doxorubicin (adriamycin) is a potent anti-cancer drug, such particles can be guided with external magnetic field to a target tissue, a carrier process that may overcome the non-specificity and efficiency of adriamycin as a drug. The nanoferrite functionalization was effected by means of acid chloride

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

    Microsoft Academic Search

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

    2005-01-01

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

  7. Magnetic properties of Co2C and Co3C nanoparticles and their assemblies

    NASA Astrophysics Data System (ADS)

    Carroll, Kyler J.; Huba, Zachary J.; Spurgeon, Steven R.; Qian, Meichun; Khanna, Shiv N.; Hudgins, Daniel M.; Taheri, Mitra L.; Carpenter, Everett E.

    2012-07-01

    Nano-composite material consisting of Co2C and Co3C nanoparticles has recently been shown to exhibit unusually large coercivities and energy products. Experimental studies that can delineate the properties of individual phases have been undertaken and provide information on how the coercivities and the energy product change with the size and composition of the nanoparticles. The studies indicate that while both phases are magnetic, the Co3C has higher magnetization and coercivity compared to Co2C. Through first principles electronic structure studies using a GGA+U functional, we provide insight on the role of C intercalation on enhancing the magnetic anisotropy of the individual phases.

  8. Design and synthesis of polymer-magnetic nanoparticle composites for use in biomedical applications

    NASA Astrophysics Data System (ADS)

    Stone, Roland Christopher

    The future of diagnostics and therapeutic drugs in biomedicine is nanoparticles. These nanoparticles come in many different shapes, sizes, and combination of materials. Magnetic nanoparticles have been studied for many years for use in biomedicine, not only for their high surface area, but also because of its unique magnetic properties. They can magnetically interact with their environment, be guided to a specific location, and manipulated to release energy in the form of heat. To ensure that these magnetic nanoparticles survive in the circulatory system, they must be modified with materials to make them colloidally stable in water and shield them from the body's immune response to foreign objects. The purpose of this project is to design and synthesize a ligand for the modification of iron oxide nanoparticles with three important characteristics: 1) water-dispersable, 2) biologically stable, and 3) functional surface. This was accomplished by synthesizing specialized heterobifunctional polyethylene oxide (PEO) that has a catechol on one end to bind strongly to iron oxide nanoparticles and an alkyne on the other end to provide further functionality. This design allows for easy customization of the particles surface, using "click chemistry," with targeting and fluorescent moieties for any desired application. The work reported discusses the techniques used for synthesizing a variety of heterobifunctional PEO via anionic ring opening polymerization of ethylene oxide and subsequent end group modifications that ultimately led to the design of a universal ligand for iron oxide nanoparticles, with improved stability in biological environments, that can be used in many biomedical applications. These universal magnetic nanoparticles were modified with different fluorescent dyes for imaging biofilms, carbohydrates for targeting bacteria, and radiotracers for multifunctional diagnostic probes to demonstrate the versatility of this surface.

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

    PubMed

    Jayalekshmi, A C; Victor, Sunita Prem; Sharma, Chandra P

    2013-01-01

    The present study focuses on the development of a biocompatible and biodegradable iron oxide incorporated chitosan-gelatin bioglass composite nanoparticles [Fe-BG]. The developed composite nanoparticle was analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, thermo gravimetric analysis (TG) and differential scanning calorimetry analysis (DSC). The size of the negatively charged composite nanoparticle was in the range of 43-51 nm. The in vitro analysis of the composite nanoparticles was carried out by cell aggregation, protein adsorption and haemolytic activity. The magnetic hysteresis value of the composite nanoparticle showed that it is a soft magnetic material. The presence of iron oxide in the chitosan-gelatin bioglass [BG] matrix enhances biodegradability as indicated in the TG studies. Iron-oxide in equal amount to bioglass in the polymer matrix has been obtained as the optimized system. The developed composite nanoparticle is a soft magnetic material and is suitable for the magnetic hyperthermia treatment and drug delivery. More detailed in vivo studies are needed to confirm the biodegradation profile and biological activity of the material. PMID:22809595

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

    SciTech Connect

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

    2010-01-15

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

  11. Surface modification and bioconjugation of FeCo magnetic nanoparticles with proteins.

    PubMed

    Wang, Wei; Jing, Ying; He, Shihai; Wang, Jian-Ping; Zhai, Jian-Ping

    2014-05-01

    Magnetic Fe70Co30 nanoparticles with a cubic shape and a mean size of 15±1.5 nm were fabricated using a magnetron-sputtering-based gas phase condensation deposition method. The particles had a high saturation magnetization of 220 emu/g, which is much higher than that of commercially available iron oxide nanoparticles. The FeCo nanoparticles were modified by 3-aminopropyltriethoxy silane and subsequently activated by glutaraldehyde, leading to successful attachment of aldehyde groups onto nanoparticle surfaces. Three proteins, namely streptavidin, PAPP-A antibody and Nectin-4 antibody, were immobilized on glutaraldehyde activated FeCo nanoparticles, and their loading levels were quantitatively evaluated. Our results show that loading capabilities are 95 ?g of streptavidin, 128 ?g of PAPP-A, and 125 ?g of Nectin-4 antibody per milligram of FeCo nanoparticles, and that the three immobilized proteins retain their binding bioactivity. The protein-FeCo conjugates may find valuable applications involving magnetic separation and purification of proteins and cells, and the magnetic detection of biomolecules. PMID:24373979

  12. Chitosan-coated magnetic nanoparticles prepared in one step by reverse microemulsion precipitation.

    PubMed

    López, Raúl G; Pineda, María G; Hurtado, Gilberto; León, Ramón Díaz de; Fernández, Salvador; Saade, Hened; Bueno, Darío

    2013-01-01

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

  13. Effect of magnetic nanoparticles on the lightning impulse breakdown voltage of transformer oil

    NASA Astrophysics Data System (ADS)

    Ghasemi, J.; Jafarmadar, S.; Nazari, M.

    2015-09-01

    In this study, the lightning impulse breakdown voltage of magnetic nanofluids based on transformer mineral oil for use in power systems was reviewed. Magnetic nanofluids are obtained from dispersion of the magnetic nanoparticles (Fe3 O4) within transformer oil, as the base fluid. The Fe3 O4 nanoparticles, using a coprecipitation method, were synthesized, coated with a surfactant, and dispersed using an ultrasonic processor, within the uninhibited transformer mineral oil NYTRO LIBRA. The lightning impulse breakdown voltage was obtained using sphere-sphere electrodes in an experimental setup for nano-oil, in volume concentration of 0.1-0.6%. Results indicate improved lightning impulse breakdown voltage under optimal conditions. Increase in the lightning impulse breakdown voltage of the nano-oil is mainly due to the dielectric and magnetic properties of Fe3 O4 nanoparticles, acting as free electrons snapper, and reduce the rate of free electrons production in the ionization process.

  14. Sub-tesla-field magnetization of vibrated magnetic nanoreagents for screening tumor markers

    NASA Astrophysics Data System (ADS)

    Chieh, Jen-Jie; Huang, Kai-Wen; Shi, Jin-Cheng

    2015-02-01

    Magnetic nanoreagents (MNRs), consisting of liquid solutions and magnetic nanoparticles (MNPs) coated with bioprobes, have been widely used in biomedical disciplines. For in vitro tests of serum biomarkers, numerous MNR-based magnetic immunoassay methods or schemes have been developed; however, their applications are limited. In this study, a vibrating sample magnetometer (VSM) was used for screening tumor biomarkers based on the same MNRs as those used in other immunoassay methods. The examination mechanism is that examined tumor biomarkers are typically conjugated to the bioprobes coated on MNPs to form magnetic clusters. Consequently, the sub-Tesla-field magnetization (Msub-T) of MNRs, including magnetic clusters, exceeds that of MNRs containing only separate MNPs. For human serum samples, proteins other than the targeted biomarkers induce the formation of magnetic clusters with increased Msub-T because of weak nonspecific binding. In this study, this interference problem was suppressed by the vibration condition in the VSM and analysis. Based on a referenced Msub-T,0 value defined by the average Msub-T value of a normal person's serum samples, including general proteins and few tumor biomarkers, the difference ?Msub-T between the measured Msub-T and the reference Msub-T,0 determined the expression of only target tumor biomarkers in the tested serum samples. By using common MNRs with an alpha-fetoprotein-antibody coating, this study demonstrated that a current VSM can perform clinical screening of hepatocellular carcinoma.

  15. Synthesis and charateristics of NdFeB magnetic nanoparticle

    Microsoft Academic Search

    Hyun Gil Cha; Young Hwan Kim; Chang Woo Kim; Young Soo Kang

    2006-01-01

    NdFeB system nanoparticles using the mixture of NdFeB-oleate complexes under the pressure of 40 Pa at 380degC with argon gas without any solvent are formed by thermal decomposition method. The produced NdFeB system nanoparticles were collected as colloidal solution of CHCl3. The morphology and size of prepared NdFeB nanoparticles were investigated with transmission electron microscopy (TEM). The chemical composition was

  16. Magnetic field induced quantum dot brightening in liquid crystal synergized magnetic and semiconducting nanoparticle composite assemblies.

    PubMed

    Amaral, Jose Jussi; Wan, Jacky; Rodarte, Andrea L; Ferri, Christopher; Quint, Makiko T; Pandolfi, Ronald J; Scheibner, Michael; Hirst, Linda S; Ghosh, Sayantani

    2015-01-14

    The design and development of multifunctional composite materials from artificial nano-constituents is one of the most compelling current research areas. This drive to improve over nature and produce 'meta-materials' has met with some success, but results have proven limited with regards to both the demonstration of synergistic functionalities and in the ability to manipulate the material properties post-fabrication and in situ. Here, magnetic nanoparticles (MNPs) and semiconducting quantum dots (QDs) are co-assembled in a nematic liquid crystalline (LC) matrix, forming composite structures in which the emission intensity of the quantum dots is systematically and reversibly controlled with a small applied magnetic field (<100 mT). This magnetic field-driven brightening, ranging between a two- to three-fold peak intensity increase, is a truly cooperative effect: the LC phase transition creates the co-assemblies, the clustering of the MNPs produces LC re-orientation at atypical low external field, and this re-arrangement produces compaction of the clusters, resulting in the detection of increased QD emission. These results demonstrate a synergistic, reversible, and an all-optical process to detect magnetic fields and additionally, as the clusters are self-assembled in a fluid medium, they offer the possibility for these sensors to be used in broad ranging fluid-based applications. PMID:25354546

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

    PubMed Central

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

    2013-01-01

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

  18. Effect of Annealing on Magnetic Properties of FePd and FePdPt Nanoparticles

    NASA Astrophysics Data System (ADS)

    Sharma, Sachil; Gajbhiye, N. S.; Ningthoujam, R. S.

    2010-12-01

    Nanoparticles of FePd and FePdPt with the average size of ˜3 nm have been prepared by modified polyol route. As-prepared nanoparticles are crystallized in fcc phase, whereas, 550-600° C annealed nanoparticles are crystallized in fct phase. As-prepared samples are superparamagnetic at 300 K, whereas, annealed samples are strongly ferromagnetic at 300 K. As compared to fct FePd nanoparticles (Hc = 1180 Oe), the fct FePdPt nanoparticles show significantly high coercivity (Hc = 4675 Oe) and squareness ratio (?r/?s = 0.71) and thus, the addition of Pt in FePd nanoalloy improves the magnetic anisotropy significantly. The Curie temperature of FePd nanoalloy increases with increasing annealing temperature because of increase of atomic ordering in fct phase.

  19. Functionalization of gold and glass surfaces with magnetic nanoparticles using biomolecular interactions.

    PubMed

    Nidumolu, Bala G; Urbina, Michelle C; Hormes, Josef; Kumar, Challa S S R; Monroe, W Todd

    2006-01-01

    Advances in nanotechnology have enabled the production and characterization of magnetic particles with nanometer-sized features that can be functionalized with biological recognition elements for numerous applications in biotechnology. In the present study, the synthesis of and interactions between self-assembled monolayers (SAMs) on gold and glass surfaces and functionalized magnetic nanoparticles have been characterized. Immobilization of 10-15 nm streptavidin-functionalized nanoparticles to biotinylated gold and glass surfaces was achieved by the strong interactions between biotin and streptavidin. Fluorescent streptavidin-functionalized nanoparticles, biotinylated surfaces, and combinations of the two were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and electron and fluorescent microscopy to confirm that little or no functionalization occurred in nonbiotinylated regions of the gold and glass surfaces compared to the biotinylated sites. Together these techniques have potential use in studying the modification and behavior of functionalized nanoparticles on surfaces in biosensing and other applications. PMID:16454497

  20. Facile and high-efficient immobilization of histidine-tagged multimeric protein G on magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Lee, Jiho; Chang, Jeong Ho

    2014-12-01

    This work reports the high-efficient and one-step immobilization of multimeric protein G on magnetic nanoparticles. The histidine-tagged (His-tag) recombinant multimeric protein G was overexpressed in Escherichia coli BL21 by the repeated linking of protein G monomers with a flexible linker. High-efficient immobilization on magnetic nanoparticles was demonstrated by two different preparation methods through the amino-silane and chloro-silane functionalization on silica-coated magnetic nanoparticles. Three kinds of multimeric protein G such as His-tag monomer, dimer, and trimer were tested for immobilization efficiency. For these tests, bicinchoninic acid (BCA) assay was employed to determine the amount of immobilized His-tag multimeric protein G. The result showed that the immobilization efficiency of the His-tag multimeric protein G of the monomer, dimer, and trimer was increased with the use of chloro-silane-functionalized magnetic nanoparticles in the range of 98% to 99%, rather than the use of amino-silane-functionalized magnetic nanoparticles in the range of 55% to 77%, respectively.

  1. Synthesis and magnetic behavior of ultra-small bimetallic FeCo/graphite nanoparticles.

    PubMed

    Castrillón, M; Mayoral, A; Urtizberea, A; Marquina, C; Irusta, S; Meier, J G; Santamaría, J

    2013-12-20

    FeCo-alloy graphite-coated nanoparticles with mean particle diameter under 8 nm have been synthesized following a CVD carbon-deficient method. The superior magnetic properties of FeCo-alloy nanoparticles makes them good candidates to be used as magnetic filler in magneto-polymer composites. Thanks to the protective effect of the graphite shell, FeCo nanoparticles are stable under oxygen atmosphere up to 200 ° C. The as-prepared nanoparticles presented a highly long range chemically ordered core being ferromagnetic at room temperature with a saturation magnetization at room temperature close to the bulk value. After annealing at 750 K the saturation magnetization and the coercive field increase. To investigate the processes involved in the thermal treatment, the temperature dependence of the magnetization and the particle composition, size and structure have been characterized before and after annealing. Besides powder x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS), a detailed study by means of advanced transmission electron microscopy (TEM) techniques has been carried out. In particular, aberration corrected scanning transmission electron microscopy (STEM), has shown that nanoparticles became faceted after the thermal treatment, as a mechanism to reach the thermodynamic equilibrium within the metastable phase. This outstanding feature, not previously reported, leads to an increase of the shape anisotropy, which in turn might be the origin of the observed increase of the coercive field after annealing. PMID:24270853

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  3. Comparison and functionalization study of microemulsion-prepared magnetic iron oxide nanoparticles.

    PubMed

    Okoli, Chuka; Sanchez-Dominguez, Margarita; Boutonnet, Magali; Järås, Sven; Civera, Concepción; Solans, Conxita; Kuttuva, Gunaratna Rajarao

    2012-06-01

    Magnetic iron oxide nanoparticles (MION) for protein binding and separation were obtained from water-in-oil (w/o) and oil-in-water (o/w) microemulsions. Characterization of the prepared nanoparticles have been performed by TEM, XRD, SQUID magnetometry, and BET. Microemulsion-prepared magnetic iron oxide nanoparticles (ME-MION) with sizes ranging from 2 to 10 nm were obtained. Study on the magnetic properties at 300 K shows a large increase of the magnetization ~35 emu/g for w/o-ME-MION with superparamagnetic behavior and nanoscale dimensions in comparison with o/w-ME-MION (10 emu/g) due to larger particle size and anisotropic property. Moringa oleifera coagulation protein (MOCP) bound w/o- and o/w-ME-MION showed an enhanced performance in terms of coagulation activity. A significant interaction between the magnetic nanoparticles and the protein can be described by changes in fluorescence emission spectra. Adsorbed protein from MOCP is still retaining its functionality even after binding to the nanoparticles, thus implying the extension of this technique for various applications. PMID:22578053

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

    PubMed Central

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

    2014-01-01

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

  5. Zinc ferrite nanoparticle as a magnetic catalyst: Synthesis and dye degradation

    SciTech Connect

    Mahmoodi, Niyaz Mohammad, E-mail: mahmoodi@icrc.ac.ir

    2013-10-15

    Graphical abstract: Photocatalytic degradation of Reactive Red 198 and Reactive Red 120 by the synthesized zinc ferrite nanoparticle. - Highlights: • Magnetic zinc ferrite nanoparticle was synthesized and characterized. • Photocatalytic dye degradation by magnetic nanoparticle was studied. • Formate, acetate and oxalate were detected as dominant dye degradation aliphatic intermediates. • Nitrate and sulfate ions were detected as mineralization products of dyes. • Zinc ferrite nanoparticle was an effective magnetic photocatalyst to degrade dyes. - Abstract: In this paper, magnetic zinc ferrite (ZnFe{sub 2}O{sub 4}) nanoparticle was synthesized and its photocatalytic dye degradation ability from colored wastewater was studied. Reactive Red 198 (RR198) and Reactive Red 120 (RR120) were used as model dyes. The characteristics of ZnFe{sub 2}O{sub 4} were investigated using Fourier transform infrared (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM). Photocatalytic dye degradation by ZnFe{sub 2}O{sub 4} was studied by UV–vis spectrophotometer and ion chromatography (IC). The effects of ZnFe{sub 2}O{sub 4} dosage, initial dye concentration and salt on dye degradation were evaluated. Formate, acetate and oxalate anions were detected as dominant aliphatic intermediate. Inorganic anions (nitrate and sulfate anions) were detected as dye mineralization products. The results indicated that ZnFe{sub 2}O{sub 4} could be used as a magnetic photocatalyst to degrade dyes from colored wastewater.

  6. Effect of spacer layer thickness on magnetic interactions in self-assembled single domain iron nanoparticles

    SciTech Connect

    Herndon, Nichole B [ORNL; Ho, S [Oak Ridge National Laboratory (ORNL); Abiade, J. [North Carolina A& T State University; Pai, Devdas M. [North Carolina A& T State University; Sankar, Jag [North Carolina A& T State University; Pennycook, Stephen J [ORNL

    2009-01-01

    The magnetic characteristics of iron nanoparticles embedded in an alumina thin film matrix have been studied as a function of spacer layer thickness. Alumina as well as iron nanoparticles were deposited in a multilayered geometry using sequential pulsed laser deposition. The role of spacer layer thickness was investigated by making layered thin film composites with three different spacer layer thicknesses 6, 12, and 18 nm with fixed iron particle size of 13 nm. Intralayer magnetic interactions being the same in each sample, the variation in coercivity and saturation magnetization is attributed to thickness dependent interlayer magnetic interactions of three types: exchange, strong dipolar, and weak dipolar. A thin film composite multilayer structure offers a continuously tunable strength of interparticle dipole-dipole interaction and is thus well suited for studies of the influence of interaction on the magnetic properties of small magnetic particle systems.

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

    SciTech Connect

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

    2013-03-31

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

  8. Structural characterization and adsorption properties of pluronic F127 onto iron oxides magnetic nanoparticles.

    PubMed

    Dehvari, Khalilalrahman; Lin, Kuen-Song; Wang, Steven S S

    2014-03-01

    Superparamagnetic iron oxide nanoparticles coated with polymers have shown low toxicity and chemical stability in physiological condition, thereby can be used to deliver encapsulated drugs throughout the body by external magnetic fields. In this study, magnetic nanoparticles were synthesized thorough co-precipitation method and their interaction with Pluronic F127 block copolymer as well as adsorption properties of polymer onto nanoparticles were investigated. Adsorption measurement revealed different adsorption behaviors below and above the polymer's critical micelle concentration. The Freundlich isotherm was found to better describe the adsorption behavior of Pluronic F127 onto SIONPs particles below the block copolymer critical micelle concentration. At higher concentration, the adsorbed amount is likely to diminish due to interpenetration of the adsorbed macromolecular micelles and volume-excluded effects for block copolymers. Furthermore, magnetic nanocomposites with different concentration of polymers were prepared through hydrothermal method. The crystalline structure, morphology, pore structure, and magnetic properties of magnetic nanoparticles/nanocomposites products at different pH and polymer concentration were studied. Results showed that due to the hematite impurities, magnetic nanocomposites synthesized at higher pH have lower magnetization. PMID:24745232

  9. Synthesis and properties of magnetic fluid based on iron nanoparticles prepared by a vapor-phase condensation process

    Microsoft Academic Search

    Ji-Hun Yu; Dong-Won Lee; Byoung-Kee Kim; Taesuk Jang

    2006-01-01

    Magnetic fluid containing metallic iron nanoparticles was successfully fabricated in this work. The iron nanoparticles were synthesized by chemical vapor condensation process and then dispersed in water-base solution (pH 11) with oleic acid as surfactant. More than 80% of iron nanoparticles were fully dispersed in the fluid and remained stable without any further oxidation over 200h. Both the iron nanoparticles

  10. Monodisperse magnetite nanoparticle tracers for in vivo magnetic particle Amit P. Khandhar, R. Matthew Ferguson, Hamed Arami, Kannan M. Krishnan*

    E-print Network

    Krishnan, Kannan M.

    disease (CKD) [3e6]. In contrast, MPI uses safe magnetic fields (no ionizing radiation) and SPIO magnetic nanoparticle tracers1 (MNTs) that are generally well tolerated in CKD patients. However, for MPI

  11. Detection and Isolation of Dendritic Cells Using Lewis X-functionalized Magnetic Nanoparticles

    PubMed Central

    Rouhanifard, Sara H.; Xie, Ran; Zhang, Guoxin; Sun, Xiaoming; Chen, Xing; Wu, Peng

    2012-01-01

    DC-specific intracellular adhesion molecule-3 grabbing non-integrin (DC-SIGN) is a receptor found on dendritic cells (DCs) that recognizes antigens bearing mannose-rich or fucosylated glycans, including Lewis X (LeX). Here, we report the fabrication of magnetic nanoparticles coated with multivalent LeX glycans using the Cu (I)-catalyzed azide-alkyne cycloaddition. The resulting nanoparticles are selective and biocompatible, serving as a highly efficient tool for DC detection and enrichment. PMID:22901307

  12. Plasma synthesis of carbon-iron magnetic nanoparticles and immobilization of doxorubicin for targeted drug delivery

    Microsoft Academic Search

    Y. Ma; S. Manolache; F. Denes; D. Vail; D. Thamm; I. Kurzman

    2006-01-01

    A novel dense-medium plasma technology (submerged arc discharge) was used to synthesize carbon\\/iron-based magnetic nanoparticles\\u000a (CMNP) from benzene or acetonitrile at room temperature and atmospheric pressure. Scanning electron microscopy shows that\\u000a the nanoparticles are spherical and 40–50 nm in diameter. Results from x-ray photoelectron spectroscopy and other analytical\\u000a techniques demonstrated that the CMNP consist of iron\\/iron oxide clusters that are

  13. Albumin-based nanoparticles as magnetic resonance contrast agents: I. Concept, first syntheses and characterisation

    Microsoft Academic Search

    M. M. Stollenwerk; I. Pashkunova-Martic; C. Kremser; H. Talasz; G. C. Thurner; A. A. Abdelmoez; E. A. Wallnöfer; A. Helbok; E. Neuhauser; N. Klammsteiner; L. Klimaschewski; E. von Guggenberg; E. Fröhlich; B. Keppler; W. Jaschke; P. Debbage

    2010-01-01

    To develop a platform for molecular magnetic resonance imaging, we prepared gadolinium-bearing albumin-polylactic acid nanoparticles\\u000a in the size range 20–40 nm diameter. Iterative cycles of design and testing upscaled the synthesis procedures to gram amounts\\u000a for physicochemical characterisation and for pharmacokinetic testing. Morphological analyses showed that the nanoparticles\\u000a were spheroidal with rough surfaces. Particle sizes were measured by direct transmission electron

  14. Doping effects of Co 2+ ions on structural and magnetic properties of ZnO nanoparticles

    Microsoft Academic Search

    Faheem Ahmed; Shalendra Kumar; Nishat Arshi; M. S. Anwar; Bon Heun Koo; Chan Gyu Lee

    In this paper, we report the synthesis of Zn1?xCoxO (0.0?x?0.10) nanoparticles by an auto-combustion method using glycine as a fuel. The prepared nanoparticles were characterized by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and DC magnetization measurements. XRD results showed that Co doped ZnO have a single phase nature with

  15. Magnetic studies of iron oxide nanoparticles coated with oleic acid and Pluronic® block copolymer

    Microsoft Academic Search

    M. A. Morales; Tapan Kumar Jain; V. Labhasetwar; D. L. Leslie-Pelecky

    2005-01-01

    We have prepared and studied iron-oxide nanoparticles coated with oleic acid (OA) and Pluronic® polymer. The mean diameter of the iron-oxide nanoparticles was 9.3(+\\/-)0.8 nm. Saturation magnetization values measured at 10 K varied from 66.1(+\\/-0.7) emu\\/g to 98.7(+\\/-0.5) emu\\/g. At 300 K the loops showed negligible coercive field. The peaks in zero-field-cooled susceptibility decreased from 280 to 168 K with

  16. Biodegradable thermoresponsive polymeric magnetic nanoparticles: a new drug delivery platform for doxorubicin

    Microsoft Academic Search

    Nidhi Andhariya; Bhupendra Chudasama; R. V. Mehta; R. V. Upadhyay

    2011-01-01

    The use of nanoparticles as drug delivery systems for anticancer therapeutics has great potential to revolutionize the future\\u000a of cancer therapy. The aim of this study is to construct a novel drug delivery platform comprising a magnetic core and biodegradable\\u000a thermoresponsive shell of tri-block-copolymer. Oleic acid-coated Fe3O4 nanoparticles and hydrophilic anticancer drug “doxorubicin” are encapsulated with PEO–PLGA–PEO (polyethylene oxide–poly d,

  17. Magnetic studies of iron oxide nanoparticles coated with oleic acid and Pluronic® block copolymer

    Microsoft Academic Search

    M. A. Morales; Tapan Kumar Jain; V. Labhasetwar; D. L. Leslie-Pelecky

    2005-01-01

    We have prepared and studied iron-oxide nanoparticles coated with oleic acid (OA) and Pluronic® polymer. The mean diameter of the iron-oxide nanoparticles was 9.3(±)0.8 nm. Saturation magnetization values measured at 10 K varied from 66.1(±0.7) emu?g to 98.7(±0.5) emu?g. At 300 K the loops showed negligible coercive field. The peaks in zero-field-cooled susceptibility decreased from 280 to 168 K with

  18. Colloidal stability of oleic- and ricinoleic-acid-coated magnetic nanoparticles in organic solvents

    Microsoft Academic Search

    Sašo Gyergyek; Darko Makovec; Miha Drofenik

    2011-01-01

    The colloidal stability of oleic- and ricinoleic-acid-coated nanoparticles in organic solvents with dielectric constants ?r ranging from 2.0 to 9.8 was studied. Although the acids are structurally similar, there is an OH group in the ricinoleic acid’s tail, a marked improvement in the colloidal stability of the ricinoleic-acid-coated magnetic nanoparticles in moderately polar organic solvents and monomer methyl methacrylate was

  19. Magnetization Process of h.c.p.CoIr Nanoparticles With Negative Uniaxial Magnetocrystalline Anisotropy

    Microsoft Academic Search

    Daiji Hasegawa; Satoshi Nakasaka; Masahiro Sato; Tomoyuki Ogawa; Migaku Takahashi

    2006-01-01

    To increase the superparamagnetic blocking frequency, we propose magnetic nanoparticles with negative uniaxial magnetocrystalline anisotropy, Ku grain. Using this material, both high ferromagnetic resonance frequency, fr, and low magnetic potential height, DeltaE, can be satisfied simultaneously. Thus, fb can be greatly improved. From the results of DC magnetization process of highly oriented h.c.p. Co83Ir17 nanogranular with negative Ku grain, it

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

    Microsoft Academic Search

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

    2009-01-01

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

  1. Enhanced magnetic properties of FePt nanoparticles codeposited on Ag nanoislands

    NASA Astrophysics Data System (ADS)

    Castaldi, L.; Giannakopoulos, K.; Travlos, A.; Boukos, N.; Niarchos, D.; Boukari, S.; Beaurepaire, E.

    2009-05-01

    Ag nanoislands have been used as nucleation sites for FePt nanoparticles when deposited on SiO2 surfaces by electron beam evaporation. We demonstrate that it is possible to nucleate FePt nanoparticles on predeposited Ag clusters and that this results in a significant improvement of the hard magnetic Ag/FePt nanoparticles' properties. We find that, besides the usual annealing treatments, a simple predeposition of Ag nanoclusters promotes the formation of the FePt L10 phase at larger FePt nominal thicknesses (fFePt). All the nanoparticles studied are ferromagnetic, except for those FePt samples deposited with lower nominal thicknesses (fFePt˜1.8 nm), which are superparamagnetic. The presence of Ag seeds promotes the A1/L10 transition, which results in a remarkable enhancement of the coercivity (Hc) for both the as-deposited and the annealed samples. Maximum Hc of 8.9 and 9.4 kOe are obtained for the Ag/FePt nanoparticles with fFePt˜1.8 and 3.5 nm, respectively. Our results are a strong indication that the nucleation of the FePt nanoparticles on Ag nanoclusters can promote significant magnetic hardening of the FePt nanoparticles by easing the transition from the disordered to the ordered phase.

  2. Recyclable antibacterial magnetic nanoparticles grafted with quaternized poly(2-(dimethylamino)ethyl methacrylate) brushes.

    PubMed

    Dong, Hongchen; Huang, Jinyu; Koepsel, Richard R; Ye, Penglin; Russell, Alan J; Matyjaszewski, Krzysztof

    2011-04-11

    Highly efficient recyclable antibacterial magnetite nanoparticles consisting of a magnetic Fe(3)O(4) core with an antibacterial poly(quaternary ammonium) (PQA) coating were prepared in an efficient four-step process. The synthetic pathway included: (1) preparation of Fe(3)O(4) nanoparticles via coprecipitation of Fe(2+)/Fe(3+) in the presence of an alkaline solution; (2) attachment of an ATRP initiating functionality to the surface of the nanoparticles; (3) surface-initiated atom transfer radical polymerization (ATRP) of 2-(dimethylamino)ethyl methacrylate (DMAEMA); and (4) transformation of PDMAEMA brushes to PQA via quaternization with ethyl bromide. The success of the surface functionalization was confirmed by FT-IR, thermal gravimetric analysis (TGA), elemental analysis, and transmission electron microscopy (TEM). The PQA-modified magnetite nanoparticles were dispersed in water and exhibited a response to an external magnetic field, making the nanoparticles easy to remove from water after antibacterial tests. The PQA-modified magnetite nanoparticles retained 100% biocidal efficiency against E. coli (10(5) to 10(6)E. coli/mg nanoparticles) during eight exposure/collect/recycle procedures without washing with any solvents or water. PMID:21384911

  3. PEGylated versus non-PEGylated magnetic nanoparticles as camptothecin delivery system

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2010-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Tran, Nhiem; Webster, Thomas J.

    2013-05-01

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

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

    PubMed

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

    2013-09-01

    Ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles are currently being used as a magnetic resonance imaging (MRI) contrast agent in vivo, mainly by their passive accumulation in tissues of interest. However, a higher specificity can ideally be achieved when the nanoparticles are targeted towards cell specific receptors and this may also facilitate specific drug delivery by an enhanced target-mediated endocytosis. We report efficient peptide-mediated targeting of magnetic nanoparticles to cells expressing the urokinase plasminogen activator receptor (uPAR), a surface biomarker for poor patient prognosis shared by several cancers including breast, colorectal, and gastric cancers. Conjugation of a uPAR specific targeting peptide onto polyethylene glycol (PEG) coated USPIO nanoparticles by click chemistry resulted in a five times higher uptake in vitro in a uPAR positive cell line compared to nanoparticles carrying a non-binding control peptide. In accordance with specific receptor-mediated recognition, a low uptake was observed in the presence of an excess of ATF, a natural ligand for uPAR. The uPAR specific magnetic nanoparticles can potentially provide a useful supplement for tumor patient management when combined with MRI and drug delivery. PMID:23835641

  7. Magnetism in nanoparticle LaCoO3

    SciTech Connect

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

    2014-06-24

    Neutron scattering and magnetometry measurements have been used to study phase transitions in LaCoO3 (LCO). For H <= 100 Oe, evidence for a ferromagnetic (FM) transition is observed at T-c approximate to 87 K. For 1 kOe <= H <= 60 kOe, no transition is apparent. For all H, Curie-Weiss analysis shows predominantly antiferromagnetic (AFM) interactions for T > T-c, but the lack of long-range AFM order indicates magnetic frustration. We argue that the weak ferromagnetism in bulk LCO is induced by lattice strain, as is the case with thin films and nanoparticles. The lattice strain is present at the bulk surfaces and at the interfaces between the LCO and a trace cobalt oxide phase. The ferromagnetic ordering in the LCO bulk is strongly affected by the Co-O-Co angle (gamma), in agreement with recent band calculations which predict that ferromagnetic long-range order can only take place above a critical value, gamma C. Consistent with recent thin film estimations, we find gamma C = 162.8 degrees. For gamma > gamma C, we observe power-law behavior in the structural parameters. gamma decreases with T until the critical temperature, T-o approximate to 37 K; below T-o the rate of change becomes very small. For T < T-o, FM order appears to be confined to regions close to the surfaces, likely due to the lattice strain keeping the local Co-O-Co angle above gamma C.

  8. Immobilization of glycolate oxidase from Medicago falcata on magnetic nanoparticles for application in biosynthesis of glyoxylic acid

    Microsoft Academic Search

    Hong Zhu; Jiang Pan; Bin Hu; Hui-Lei Yu; Jian-He Xu

    2009-01-01

    Glycolate oxidase was isolated from Medicago falcata Linn. after a screening from 13 kinds of C3 plant leaves, with higher specific activity than the enzyme from spinach. The M. falcata glycolate oxidase (MFGO) was partially purified and then immobilized onto hydrothermally synthesized magnetic nanoparticles via physical adsorption. The magnetic nanoparticles were characterized with scanning electron microscope (SEM), transmission electron microscopy

  9. Controlled oxidation of FeCo magnetic nanoparticles to produce faceted FeCo/ferrite nanocomposites for rf heating applications

    E-print Network

    Laughlin, David E.

    Controlled oxidation of FeCo magnetic nanoparticles to produce faceted FeCo/ferrite nanocomposites for polydisperse FeCo magnetic nanoparticles MNPs synthesized using an induction plasma torch. X-ray diffraction to promote oxidation and XRD was used to follow the evolution of the FeCo core and the Fe3O4 and FeO oxide

  10. Correlation between uropathogenic properties of Escherichia coli from urinary tract infections and the antibody-coated bacteria test and comparison with faecal strains.

    PubMed Central

    Brooks, H. J.; Benseman, B. A.; Peck, J.; Bettelheim, K. A.

    1981-01-01

    Strains of Escherichia coli isolated from adult females with symptomatic urinary tract infection were found to possess the following properties significantly more frequently than faecal strains: (i) high K-antigen titre: (ii) haemolysin; (iii) type 1 pili; (iv) mannose-resistant haemagglutination; (v) fermentation of dulcitol and salicin; (vi) O serotype 2, 6 and 75; (vii) H serotype 1. E. coli isolated form urine specimens containing significant numbers of antibody-coated bacteria were richer in these seven properties than strains from urines without detectable antibody coated bacteria. The O and H serotypes of E. coli obtained from patients with urinary tract infection in two New Zealand cities were compared with those reported in the world literature and found to be similar. PMID:6114119

  11. Frequency-domain birefringence measurement of biological binding to magnetic nanoparticles

    PubMed Central

    Ku, Benjamin Y.; Chan, Mei-Lin; Ma, Zhiya; Horsley, David A.

    2010-01-01

    Optical detection of the frequency-dependent magnetic relaxation signal is used to monitor the binding of biological molecules to magnetic nanoparticles in a ferrofluid. Biological binding reactions cause changes in the magnetic relaxation signal due to an increase in the average hydrodynamic diameter of the nanoparticles. To allow the relaxation signal to be detected in dilute ferrofluids, measurements are made using a balanced photodetector, resulting in a 25 ?V/?Hz noise floor, within 50% of the theoretical limit imposed by photon shot noise. Measurements of a ferrofluid composed of magnetite nanoparticles coated with anti-IgG antibodies show that the average hydrodynamic diameter increases from 115.2 to 125.4 nm after reaction with IgG. PMID:20463913

  12. Reflective and magnetic properties of photonic polymer composite materials based on porous silicon and magnetite nanoparticles.

    PubMed

    Kim, Jihoon; Koh, Youngdae; Jang, Seunghyun; Jung, Kyoungsun; Woo, Hee-Gweon; Kim, Sungsoo; Sohn, Honglae

    2010-05-01

    Photonic polymer composite materials exhibiting both reflective and magnetic properties were prepared by the replication of rugate porous silicon (PS) using polystyrene and magnetite nanoparticle (Fe3O4). Rugate PS prepared by applying a computer-generated pseudo-sinusoidal current waveform resulted in a mirror with high reflectivity in a specific narrow spectral region and served as a template for replicating its nanostructure with polystyrene containing the magnetic nanoparticles of magnetite. The composite films replicated a sharp photonic resonance with full-width at half maximum (FWHM) of 20 nm from rugate PS in the reflectivity spectrum as well as displayed a magnetic property of magnetite nanoparticles in SQUID magnetometry. Optical characteristics of composite films indicated that the surface of polymer film had a negative structure of rugate PS. The composite films were stable in aqueous solutions for several days without any degradation. PMID:20358975

  13. Domain size correlated magnetic properties and electrical impedance of size dependent nickel ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Kamble, Ramesh B.; Varade, Vaibhav; Ramesh, K. P.; Prasad, V.

    2015-01-01

    We report here the investigations on the size dependent variation of magnetic properties of nickel ferrite nanoparticles. Nickel ferrite nanoparticles of different sizes (14 to 22 nm) were prepared by the sol-gel route at different annealing temperatures. They are characterized by TGA-DTA, XRD, SEM, TEM and Raman spectroscopy techniques for the confirmation of the temperature of phase formation, thermal stability, crystallinity, morphology and structural status of the nickel ferrite nanoparticles. The magnetization studies revealed that the saturation magnetization (Ms), retentivity (Mr) increase, while coercivity (Hc) and anisotropy (Keff) decrease as the particle size increases. The observed value of Ms is found to be relatively higher for a particle size of 22 nm. In addition, we have estimated the magnetic domain size using magnetic data and correlated to the average particle size. The calculated magnetic domain size is closely matching with the particle size estimated from XRD. Impedance spectroscopy was employed to study the samples in an equivalent circuit to understand their transport phenomena. It shows that nickel ferrite nanoparticles exhibit a non-Debye behavior with increasing particle size due to the influence of increasing disorders, surface effects, grain size and grain boundaries, etc.

  14. Polyol-process-derived CoPt nanoparticles: Structural and magnetic properties

    NASA Astrophysics Data System (ADS)

    Chinnasamy, C. N.; Jeyadevan, B.; Shinoda, K.; Tohji, K.

    2003-05-01

    We report the synthesis and magnetic properties of CoPt nanoparticles by using the polyol process. Since the reduction potential of Pt is more positive than Co, Pt is easily reduced compared to Co. Hence, CoPt nanoparticles were realized by coreducing cobalt and platinum acetylacetonate in the presence of an appropriate amount of OH ions in trimethylene glycol. X-ray diffraction and transmission electron microscopy studies showed that the as-synthesized CoPt nanoparticles had fcc structure and about 5 nm in diameter. Composition analysis reveals that the as-synthesized particles are almost equiatomic Co50Pt50. Magnetic characterization revealed that these nanoparticles are ferromagnetic at room temperature, and that the magnetization and coercivity values were 8 emu/g and 380 Oe, respectively. Differential scanning calorimetry studies showed that the ordering temperature of the as-synthesized particles was only 550 °C (peak temperature), against 825 °C of the bulk. Annealing the CoPt nanoparticles above 550 °C induced ordering with enhanced magnetic properties.

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

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

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

  16. Cobalt Zinc Ferrite Nanoparticles as a Potential Magnetic Resonance Imaging Agent: An In vitro Study

    PubMed Central

    Ghasemian, Zeinab; Shahbazi-Gahrouei, Daryoush; Manouchehri, Sohrab

    2015-01-01

    Background: Magnetic Nanoparticles (MNP) have been used for contrast enhancement in Magnetic Resonance Imaging (MRI). In recent years, research on the use of ferrite nanoparticles in T2 contrast agents has shown a great potential application in MR imaging. In this work, Co0.5Zn0.5Fe2O4 and Co0.5Zn0.5Fe2O4-DMSA magnetic nanoparticles, CZF-MNPs and CZF-MNPs-DMSA, were investigated as MR imaging contrast agents. Methods: Cobalt zinc ferrite nanoparticles and their suitable coating, DMSA, were investigated under in vitro condition. Human prostate cancer cell lines (DU145 and PC3) with bare (uncoated) and coated magnetic nanoparticles were investigated as nano-contrast MR imaging agents. Results: Using T2-weighted MR images identified that signal intensity of bare and coated MNPs was enhanced with increasing concentration of MNPs in water. The values of 1/T2 relaxivity (r2) for bare and coated MNPs were found to be 88.46 and 28.80 (mM?1 s?1), respectively. Conclusion: The results show that bare and coated MNPs are suitable as T2-weighted MR imaging contrast agents. Also, the obtained r2/r1 values (59.3 and 50) for bare and coated MNPs were in agreement with the results of other previous relevant works.

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

    PubMed

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

    2013-01-28

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

  18. Electrical and Magnetic Properties of Polymer Electrolyte PVA.LiOH Dispersed by Fe3O4 Nanoparticles

    NASA Astrophysics Data System (ADS)

    Aji, Mahardika Prasetya; Rahmawati; Masturi; Bijaksana, Satria; Khairurrijal; Abdullah, Mikrajuddin

    2011-12-01

    Nanocomposite magnetic polymer electrolyte based on poly (vinyl alcohol) (PVA) with lithium hydroxide (LiOH) dispersed by magnetite (Fe3O4) nanoparticle as inorganic filler were prepared by using an in-situ method. Ions carriers were inserted during the growth of the nanoparticles that had been contributed by a precursor. The effect upon the addition of Fe3O4 nanoparticles on the ionic conductivity of the composite polymer electrolytes was investigated, and it was proven that the ionic conductivity had been enhanced. Maximum conductivity was obtained upon addition of Fe3O4 nanoparticles, i.e. 1.81×10-3S.cm-1. The magnetic properties of nanocomposite magnetic polymer electrolyte were observed by magnetic susceptibility studies. The magnetic susceptibility data revealed that polymer electrolyte PVA.LiOH dispersed by Fe3O4 nanoparticle was found predominantly ferrimagnetism.

  19. Structural, static and dynamic magnetic properties of dextran coated ?-Fe(2)O(3) nanoparticles studied by (57)Fe NMR, Mössbauer, TEM and magnetization measurements.

    PubMed

    Fardis, M; Douvalis, A P; Tsitrouli, D; Rabias, I; Stamopoulos, D; Kehagias, Th; Karakosta, E; Diamantopoulos, G; Bakas, T; Papavassiliou, G

    2012-04-18

    The structural and magnetic properties and spin dynamics of dextran coated and uncoated ?-Fe(2)O(3) (maghemite) nanoparticles have been investigated using high resolution transmission electron microscopy (HRTEM), (57)Fe nuclear magnetic resonance (NMR), Mössbauer spectroscopy and dc magnetization measurements. The HRTEM observations indicated a well-crystallized system of ellipsoid-shaped nanoparticles, with an average size of 10 nm. The combined Mössbauer and magnetic study suggested the existence of significant interparticle interactions not only in the uncoated but also in the dextran coated nanoparticle assemblies. The zero-field NMR spectra of the nanoparticles at low temperatures are very similar to those of the bulk material, indicating the same hyperfine field values at saturation in accord with the performed Mössbauer measurements. The T(2) NMR spin-spin relaxation time of the nanoparticles has also been measured as a function of temperature and found to be two orders of magnitude shorter than that of the bulk material. It is shown that the thermal fluctuations in the longitudinal magnetization of the nanoparticles in the low temperature limit may account for the shortening and the temperature dependence of the T(2) relaxation time. Thus, the low temperature NMR results are in accord with the mechanism of collective magnetic excitations, due to the precession of the magnetization around the easy direction of the magnetization at an energy minimum, a mechanism originally proposed to interpret Mössbauer experiments in magnetic nanoparticles. The effect of the surface spins on the NMR relaxation mechanisms is also discussed. PMID:22418594

  20. Self-Assembly and Tunneling Magneto Resistance of Magnetic Nanoparticle Superlattices

    NASA Astrophysics Data System (ADS)

    Lekshmi Indira, Chaitanya; Nobile, Concetta; Bounsanti, Raffaella; D'Amone, Eliana; Cozzoli, Davide; Maruccio, Giuseppe

    2009-03-01

    Template assisted self-assembly of magnetic oxide nanostructures into systematically ordered superlattices in presence of magnetic field can offer controlled interfaces and useful properties for the fabrication of magnetically engineered tunnel junctions with application in high performance magnetic random access memories. In our work we employ magnetite, an important class of half-metallic material showing super paramagnetic behavior close to room temperature and valuable coercivity at low temperatures, as nanoparticles. The self-assembly of nanoparticle superlattices on metallic non-magnetic substrates is demonstrated. Further, enhanced spin-dependent electron transport and tunneling magneto resistance in devices with crossbar geometry is discussed. *M. P. Pileni, J. Phys. D: Appl. Phys. 41, 134002 (2008). *Z. M. Liao et al. Nano Lett. 6, 1087 (2006). *K. Yakushiji et al. Nat. Mater. 4, 57 (2005).

  1. Comparison of the effects of antibody-coated liposomes, IVIG, and anti-RBC immunotherapy in a murine model of passive chronic immune thrombocytopenia

    PubMed Central

    Deng, Rong

    2007-01-01

    The present work evaluated antibody-coated liposomes as a new treatment strategy for immune thrombocytopenic purpura (ITP) through the use of a mouse model of the disease. Effects of antimethotrexate antibody (AMI)–coated liposomes and intravenous immunoglobulin (IVIG)–coated liposomes (15, 30, 60 ?mol lipid/kg) were compared with the effects of IVIG (0.4, 1, 2 g/kg) and anti–red blood cell (anti-RBC) monoclonal antibody immunotherapy (TER119, 5, 15, 25, and 50 ?g/mouse) on MWReg30-induced thrombocytopenia. Each treatment was found to attenuate thrombocytopenia in a dose-dependent manner and, consistent with previous work, IVIG was found to increase antiplatelet antibody clearance in a dose-dependent manner. TER119 demonstrated greater effects on thrombocytopenia relative to other therapies (peak platelet counts: 224% ± 34% of initial platelet counts for 50 ?g TER119/mouse versus 160% ± 34% for 2 g/kg IVIG, 88% ± 36% for 60 ?mol lipid/kg AMI-coated liposomes, and 80% ± 25% for 60 ?mol lipid/kg IVIG-coated liposomes). However, the effects of TER119 were associated with severe hemolysis, as TER119 decreased RBC counts by approximately 50%. The present work demonstrated that antibody-coated liposomes attenuated thrombocytopenia in this model at a much lower immunoglobulin dose than that required for IVIG effects and, in contrast with TER119, antibody-coated liposomes increased platelet counts without altering RBC counts. PMID:17132715

  2. Modeling of Magnetic Nanoparticles Transport in Shale Reservoirs

    E-print Network

    An, Cheng

    2014-12-18

    Currently, the application of nanoparticles has attracted much attention due to the potential of nanotechnology to lead to evolutionary changes in the petroleum industry. The literature contains numerous references to the possible use...

  3. Colloidal stability of magnetic nanoparticles in molten salts

    E-print Network

    Somani, Vaibhav (Vaibhav Basantkumar)

    2010-01-01

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

  4. Increase of magnetic hyperthermia efficiency due to dipolar interactions in low-anisotropy magnetic nanoparticles: Theoretical and experimental results

    NASA Astrophysics Data System (ADS)

    Mehdaoui, B.; Tan, R. P.; Meffre, A.; Carrey, J.; Lachaize, S.; Chaudret, B.; Respaud, M.

    2013-05-01

    When magnetic nanoparticles (MNPs) are single domain and magnetically independent, their magnetic properties and the conditions to optimize their efficiency in magnetic hyperthermia applications are now well understood. However, the influence of magnetic interactions on magnetic hyperthermia properties is still unclear. Here, we report hyperthermia and high-frequency hysteresis loop measurements on a model system consisting of MNPs with the same size but a varying anisotropy, which is an interesting way to tune the relative strength of magnetic interactions. A clear correlation between the MNP anisotropy and the squareness of their hysteresis loop in colloidal solution is observed: the larger the anisotropy, the smaller the squareness. Since low anisotropy MNPs display a squareness higher than the one of magnetically independent nanoparticles, magnetic interactions enhance their heating power in this case. Hysteresis loop calculations of independent and coupled MNPs are compared to experimental results. It is shown that the observed features are a natural consequence of the formation of chains and columns of MNPs during hyperthermia experiments: in these structures, when the MNP magnetocristalline anisotropy is small enough to be dominated by magnetic interactions, the hysteresis loop shape tends to be rectangular, which enhances their efficiency. On the contrary, when MNPs do not form chains and columns, magnetic interactions reduce the hysteresis loop squareness and the efficiency of MNPs compared to independent ones. Our finding can thus explain contradictory results in the literature on the influence of magnetic interactions on magnetic hyperthermia. It also provides an alternate explanation to some experiments where an enhanced specific absorption rate for MNPs in liquids has been found compared to the one of MNPs in gels, usually interpreted with some contribution of the brownian motion. The present work should improve the understanding and interpretation of magnetic hyperthermia experiments.

  5. Magnetic and Spin-Transport Properties of Magnetite Nanoparticles

    Microsoft Academic Search

    Kai Liu; L. Zhao; P. Klavins; Frank E. Osterloh; H. Hiramatsu; S. B. Ritchey; C. S. Fadley

    2003-01-01

    Nanoparticles of magnetite (Fe_3O_4) have been synthesized using an aqueous precipitation technique. The particles are spherical in shape, with an average size of 8-9 nm and a small size distribution, revealed by transmission electron microscopy and atomic force microscopy. Structural and chemical characterizations have been carried out by x-ray diffraction, x-ray photoelectron spectroscopy, and chemical titration. Dispersed nanoparticles displays superparamagnetic

  6. Imaging the delivery of brain-penetrating PLGA nanoparticles in the brain using magnetic resonance.

    PubMed

    Strohbehn, Garth; Coman, Daniel; Han, Liang; Ragheb, Ragy R T; Fahmy, Tarek M; Huttner, Anita J; Hyder, Fahmeed; Piepmeier, Joseph M; Saltzman, W Mark; Zhou, Jiangbing

    2015-02-01

    Current therapy for glioblastoma multiforme (GBM) is largely ineffective, with nearly universal tumor recurrence. The failure of current therapy is primarily due to the lack of approaches for the efficient delivery of therapeutics to diffuse tumors in the brain. In our prior study, we developed brain-penetrating nanoparticles that are capable of penetrating brain tissue and distribute over clinically relevant volumes when administered via convection-enhanced delivery (CED). We demonstrated that these particles are capable of efficient delivery of chemotherapeutics to diffuse tumors in the brain, indicating that they may serve as a groundbreaking approach for the treatment of GBM. In the original study, nanoparticles in the brain were imaged using positron emission tomography (PET). However, clinical translation of this delivery platform can be enabled by engineering a non-invasive detection modality using magnetic resonance imaging (MRI). For this purpose, we developed chemistry to incorporate superparamagnetic iron oxide (SPIO) into the brain-penetrating nanoparticles. We demonstrated that SPIO-loaded nanoparticles, which retain the same morphology as nanoparticles without SPIO, have an excellent transverse (T(2)) relaxivity. After CED, the distribution of nanoparticles in the brain (i.e., in the vicinity of injection site) can be detected using MRI and the long-lasting signal attenuation of SPIO-loaded brain-penetrating nanoparticles lasted over a one-month timecourse. Development of these nanoparticles is significant as, in future clinical applications, co-administration of SPIO-loaded nanoparticles will allow for intraoperative monitoring of particle distribution in the brain to ensure drug-loaded nanoparticles reach tumors as well as for monitoring the therapeutic benefit with time and to evaluate tumor relapse patterns. PMID:25403507

  7. Aerosol synthesis and surface functionalization of luminescent silicon nanoparticles, aerosol synthesis of magnetic nanoparticles, and kinetic Monte Carlo simulation of silicon nanoparticle nucleation

    NASA Astrophysics Data System (ADS)

    Li, Xuegeng

    The primary accomplishment of the research presented in this thesis is the development of a technology to produce light emitting silicon nanoparticles in macroscopic quantities by gas phase laser-driven pyrolysis of silane and post etching treatment. Theoretical exploration of the homogenous gas phase particle nucleation during pyrolysis of silane is another parallel focus of this thesis. Production of nano-scale materials by CO2 laser-driven gas phase reactions has been studied by several groups during the past two decades. The particle sizes can be controlled to below 10 nm. Although the silicon nanoparticles that are produced by this method are not photoluminescent, we have discovered that etching these particles with HF/HNO3 mixture can controllably reduce their size and passivate their surface such that they become photoluminescent. The photoluminescence can be controlled by the etching conditions. In order to obtain silicon nanoparticles with stable photoluminescence properties and stable colloidal dispersions for further applications, it is important to passivate the silicon nanoparticle surfaces and coat them with functional groups. Well-dispersed particle dispersions with stable PL were obtained after surface functionalization. This provides an important step toward the further potential applications of silicon nanoparticles. One key advantage of the gas phase laser pyrolysis process is the flexibility to make nanoparticles of different materials. Nickel and iron nanoparticles were produced successfully with controlled size distribution. Preliminary results show that this method is capable of producing metallic nanoparticles with interesting magnetic properties. Kinetic Monte Carlo simulation of particle nucleation during thermal decomposition of silane can also be used to obtain useful information about the synthesis of silicon nanoparticles. In this approach, a simulation follows the evolution of a single silicon-hydrogen cluster as it reacts with its environment and grows, possibly to eventually become a particle, or disintegrates. An improved group additivity method is used to estimate the thermochemical properties of silicon-hydrogen clusters, and thermochemically-based reactivity rules are used to estimate the rate parameters for reactions of these clusters. Useful information, such as free energy profiles, cluster size distributions, effective reaction rate constants and critical particle nucleus sizes, can be extracted from the kinetic Monte Carlo simulations.

  8. Magnetic field activated lipid-polymer hybrid nanoparticles for stimuli-responsive drug release.

    PubMed

    Kong, Seong Deok; Sartor, Marta; Hu, Che-Ming Jack; Zhang, Weizhou; Zhang, Liangfang; Jin, Sungho

    2013-03-01

    Stimuli-responsive nanoparticles (SRNPs) offer the potential of enhancing the therapeutic efficacy and minimizing the side-effects of chemotherapeutics by controllably releasing the encapsulated drug at the target site. Currently controlled drug release through external activation remains a major challenge during the delivery of therapeutic agents. Here we report a lipid-polymer hybrid nanoparticle system containing magnetic beads for stimuli-responsive drug release using a remote radio frequency (RF) magnetic field. These hybrid nanoparticles show long-term stability in terms of particle size and polydispersity index in phosphate-buffered saline (PBS). Controllable loading of camptothecin (CPT) and Fe(3)O(4) in the hybrid nanoparticles was demonstrated. RF-controlled drug release from these nanoparticles was observed. In addition, cellular uptake of the SRNPs into MT2 mouse breast cancer cells was examined. Using CPT as a model anticancer drug the nanoparticles showed a significant reduction in MT2 mouse breast cancer cell growth in vitro in the presence of a remote RF field. The ease of preparation, stability, and controllable drug release are the strengths of the platform and provide the opportunity to improve cancer chemotherapy. PMID:23149252

  9. Synthesis, Stability, Cellular Uptake, and Blood Circulation Time of Carboxymethyl-Inulin Coated Magnetic Nanoparticles

    PubMed Central

    Santiago-Rodríguez, Lenibel; Lafontaine, Moises Montalvo; Castro, Cristina; Méndez-Vega, Janet; Latorre-Esteves, Magda; Juan, Eduardo J.; Mora, Edna; Torres-Lugo, Madeline; Rinaldi, Carlos

    2013-01-01

    Iron oxide nanoparticles were coated with the biocompatible, biodegradable, non-immunogenic polysaccharide inulin by introduction of carboxyl groups into the inulin structure and conjugation with amine groups on the surface of iron oxide nanoparticles grafted with 3-aminopropyltriethoxysilane. The resulting nanoparticles were characterized by FT-IR spectroscopy, transmission electron microscopy, dynamic light scattering, zeta potential, SQUID magnetometry, and with respect to their energy dissipation rate in applied alternating magnetic fields. The nanoparticles had a hydrodynamic diameter in the range of 70 ± 10 nm and were superparamagnetic, with energy dissipation rates in the range of 58–175 W/g for an applied field frequency of 233 kHz and an applied field amplitude in the range of 20–48 kA/m. The nanoparticles were stable in a range of pH, at temperatures between 23°C and 53°C, and in short term storage in water, PBS, and culture media. The particles were non-cytotoxic to the immortalized human cancer cell lines Hey A8 FDR, A2780, MDA 468, MCF-7 and Caco-2. The nanoparticles were readily taken up by Caco-2 cells in a time and concentration dependent fashion, and were found to have a pharmacokinetic time constant of 47 ± 3 min. The small size, non-cytotoxicity, and efficient energy dissipation of the particles could make them useful for biomedical applications such as magnetic fluid hyperthermia. PMID:23914296

  10. Radiation induced structural and magnetic transformations in nanoparticle MnxZn(1-x)Fe2O4 ferrites

    NASA Astrophysics Data System (ADS)

    Naik, P. P.; Tangsali, R. B.; Sonaye, B.; Sugur, S.

    2015-07-01

    Nanoparticle magnetic materials are suitable for multiple modern high end medical applications like targeted drug delivery, gene therapy, hyperthermia and MR thermometry imaging. Majority of these applications are confined to use of Mn-Zn ferrite nanoparticles. These nanoparticles are normally left in the body after their requisite application. Preparing these nanoparticles is usually a much involved job. However with the development of the simple technique MnxZn1-xFe2O4 nanoparticles could be prepared with much ease. The nanoparticles of MnxZn1-xFe2O4 with (x=1.0, 0.7, 0.5, 0.3, 0.0) were prepared and irradiated with gamma radiation of various intensities ranging between 500 R to 10,000 R, after appropriate structural and magnetic characterization. Irradiated samples were investigated for structural and magnetic properties, as well as for structural stability and cation distribution. The irradiated nanoparticles exhibited structural stability with varied cation distribution and magnetic properties, dependent on gamma radiation dose. Surprisingly samples also exhibited quenching of lattice parameter and particle size. The changes introduced in the cation distribution, lattice constant, particle size and magnetic properties were found to be irreversible with time lapse and were of permanent nature exhibiting good stability even after several months. Thus the useful properties of nanoparticles could be enhanced on modifying the cation distribution inside the nanoparticles by application of gamma radiation.

  11. Exchange-coupled nanocomposite magnets by nanoparticle self-assembly

    Microsoft Academic Search

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

    2002-01-01

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

  12. Magnetic anisotropy and organization of nanoparticles in heads and antennae of neotropical leaf-cutter ants, Atta colombica

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oriented magnetic nanoparticles have been suggested as a good candidate for a magnetic sensor in ants. Behavioral evidence for a magnetic compass in Neotropical leafcutter ants, Atta colombica (Formicidae: Attini), motivated a study of the arrangement of magnetic particles in the ants’ four major bo...

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

    NASA Astrophysics Data System (ADS)

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

    2010-09-01

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

  14. 1H relaxation enhancement induced by nanoparticles in solutions: Influence of magnetic properties and diffusion

    NASA Astrophysics Data System (ADS)

    Kruk, D.; Korpa?a, A.; Taheri, S. Mehdizadeh; Koz?owski, A.; Förster, S.; Rössler, E. A.

    2014-05-01

    Magnetic nanoparticles that induce nuclear relaxation are the most promising materials to enhance the sensitivity in Magnetic Resonance Imaging. In order to provide a comprehensive understanding of the magnetic field dependence of the relaxation enhancement in solutions, Nuclear Magnetic Resonance 1H spin-lattice relaxation for decalin and toluene solutions of various Fe2O3 nanoparticles was investigated. The relaxation experiments were performed in a frequency range of 10 kHz-20 MHz by applying Field Cycling method, and in the temperature range of 257-298 K, using nanoparticles differing in size and shape: spherical - 5 nm diameter, cubic - 6.5 nm diameter, and cubic - 9 nm diameter. The relaxation dispersion data were interpreted in terms of a theory of nuclear relaxation induced by magnetic crystals in solution. The approach was tested with respect to its applicability depending on the magnetic characteristics of the nanocrystals and the time-scale of translational diffusion of the solvent. The role of Curie relaxation and the contributions to the overall 1H spin-lattice relaxation associated with the electronic spin-lattice and spin-spin relaxation was thoroughly discussed. It was demonstrated that the approach leads to consistent results providing information on the magnetic (electronic) properties of the nanocrystals, i.e., effective electron spin and relaxation times. In addition, features of the 1H spin-lattice relaxation resulting from the electronic properties of the crystals and the solvent diffusion were explained.

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

    PubMed Central

    Arami, Hamed; Krishnan, Kannan M.

    2014-01-01

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

  16. Novel magnetic fibrin hydrogel scaffolds containing thrombin and growth factors conjugated iron oxide nanoparticles for tissue engineering

    PubMed Central

    Ziv-Polat, Ofra; Skaat, Hadas; Shahar, Abraham; Margel, Shlomo

    2012-01-01

    Novel tissue-engineered magnetic fibrin hydrogel scaffolds were prepared by the interaction of thrombin-conjugated iron oxide magnetic nanoparticles with fibrinogen. In addition, stabilization of basal fibroblast growth factor (bFGF) was achieved by the covalent and physical conjugation of the growth factor to the magnetic nanoparticles. Adult nasal olfactory mucosa (NOM) cells were seeded in the transparent fibrin scaffolds in the absence or presence of the free or conjugated bFGF-iron oxide nanoparticles. The conjugated bFGF enhanced significantly the growth and differentiation of the NOM cells in the fibrin scaffolds, compared to the same or even five times higher concentration of the free bFGF. In the presence of the bFGF-conjugated magnetic nanoparticles, the cultured NOM cells proliferated and formed a three-dimensional interconnected network composed mainly of tapered bipolar cells. The magnetic properties of these matrices are due to the integration of the thrombin- and bFGF-conjugated magnetic nanoparticles within the scaffolds. The magnetic properties of these scaffolds may be used in future work for various applications, such as magnetic resonance visualization of the scaffolds after implantation and reloading the scaffolds via magnetic forces with bioactive agents, eg, growth factors bound to the iron oxide magnetic nanoparticles. PMID:22419873

  17. Preparation of magnetic gelatin nanoparticles and investigating the possible use as chemotherapeutic agent.

    PubMed

    Y?lmaz, Habibe; Sanl?er, Senay Hamarat

    2013-04-01

    Iron oxide nanoparticles coated with gelatin trough two-step desolvation method and characterized. SEM analyse showed that the nanoparticles are spherical and TEM image showed that the iron oxide nanoparticles encapsulated with gelatin. Also FTIR, TG and magnetization analyses exhibited that iron oxide nanoparticles encapsulated as well. Drug loading by adsorption studied under various conditions as different temperature, contact time and initial cisplatin concentration. Also, Langmuir, Freundlich and Dubinin-Raduskevich adsorption isotherm curves were constracted and constants were calculated. In vitro drug release was performed at pH 5 and 7.4 and hyperthermic drug release investigated at 42°C and compared with non-hyperthermic drug release. PMID:23305120

  18. Magnetic properties of iron-oxide passivated iron nanoparticles synthesized by a gas condensation technique

    NASA Astrophysics Data System (ADS)

    Baker, Colin C.

    Gas phase synthesis processes involve the generation of metal atoms through various means, and the homogeneous nucleation and subsequent condensation and coagulation of nanoparticles. Inert gas condensation (IGC) is a desirable process for the synthesis of metal nanoparticles because it is a relatively simple process capable of producing large quantities of nanoparticles, and since it utilizes vacuum deposition, it offers high purity particles and does not require hazardous chemicals. In this research, the results of the IGC synthesis of iron nanoparticles are presented. The iron nanoparticles are passivated in-situ by slowly introducing oxygen into the chamber to form ferrimagnetic Fe3O4 gamma-Fe2O3 shell/alpha-Fe ferromagnetic core nanoparticles. The magnetic properties of these particles are investigated as a function of passivation layer thickness and particle concentration. The oxide-passivated particles exhibit an exchange bias when cooled below a blocking temperature, which depends on the thickness of the oxide layer present. It was found that the exchange bias increased with oxide thickness. Similarly the blocking temperature also increased with oxide layer thickness. The blocking temperature in all cases, however, was found to be much lower than the Neel temperature for Fe-oxides. The nanoparticles also exhibit a spin glass transition below a characteristic freezing temperature, as evident by a sharp increase in the magnetic moment of the samples. Fe nanoparticle-polymer composite films were also obtained by spin casting mixtures of nanoparticles and polymethylmethacrylate (PMMA). The magnetic properties of these composites were compared to those of particles compressed into pellets. It was observed that when the particles were dispersed into the nanocomposite, the coercivity was increased, suggesting a heightened anisotropy barrier. Similarly, the magnetic relaxation results indicated that the particles dispersed in the PMMA exhibited significantly reduced relaxations through the entire temperature range, as compared to the non-dispersed compressed pellets. It is hoped that this research will result in a greater understanding of the interaction effects between magnetic species. The Fe-oxide/Fe shell/core interactions, may give researchers a better understanding of short-range exchange interactions, while Fe/PMMA composites may elucidate the nature and scope of longer-range dipolar interactions.

  19. Morphology and magnetic flux distribution in superparamagnetic, single-crystalline Fe{sub 3}O{sub 4} nanoparticle rings

    SciTech Connect

    Takeno, Yumu [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Murakami, Yasukazu, E-mail: murakami@tagen.tohoku.ac.jp, E-mail: kannanmk@uw.edu; Shindo, Daisuke [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Center for Emergent Matter Science, RIKEN, Wako 351-0198 (Japan); Sato, Takeshi [Hitachi High-Technologies Corporation, 1040 Ichige, Hitachinaka-shi, Ibaraki 312-0033 (Japan); Tanigaki, Toshiaki [Center for Emergent Matter Science, RIKEN, Wako 351-0198 (Japan); Central Research Laboratory, Hitachi, Ltd., Hatoyama 350-0395 (Japan); Park, Hyun Soon [Center for Emergent Matter Science, RIKEN, Wako 351-0198 (Japan); Department of Materials Science and Engineering, Dong-A University, Busan 604-714, Republic of South Korea (Korea, Republic of); Ferguson, R. Matthew [LodeSpin Labs, P.O. Box 95632, Seattle, Washington 91845 (United States); Krishnan, Kannan M., E-mail: murakami@tagen.tohoku.ac.jp, E-mail: kannanmk@uw.edu [Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195-2120 (United States)

    2014-11-03

    This study reports on the correlation between crystal orientation and magnetic flux distribution of Fe{sub 3}O{sub 4} nanoparticles in the form of self-assembled rings. High-resolution transmission electron microscopy demonstrated that the nanoparticles were single-crystalline, highly monodispersed, (25?nm average diameter), and showed no appreciable lattice imperfections such as twins or stacking faults. Electron holography studies of these superparamagnetic nanoparticle rings indicated significant fluctuations in the magnetic flux lines, consistent with variations in the magnetocrystalline anisotropy of the nanoparticles. The observations provide useful information for a deeper understanding of the micromagnetics of ultrasmall nanoparticles, where the magnetic dipolar interaction competes with the magnetic anisotropy.

  20. Effect of magnetic dipolar interactions on nanoparticle heating efficiency: Implications for cancer hyperthermia

    PubMed Central

    Branquinho, Luis C.; Carrião, Marcus S.; Costa, Anderson S.; Zufelato, Nicholas; Sousa, Marcelo H.; Miotto, Ronei; Ivkov, Robert; Bakuzis, Andris F.

    2013-01-01

    Nanostructured magnetic systems have many applications, including potential use in cancer therapy deriving from their ability to heat in alternating magnetic fields. In this work we explore the influence of particle chain formation on the normalized heating properties, or specific loss power (SLP) of both low- (spherical) and high- (parallelepiped) anisotropy ferrite-based magnetic fluids. Analysis of ferromagnetic resonance (FMR) data shows that high particle concentrations correlate with increasing chain length producing decreasing SLP. Monte Carlo simulations corroborate the FMR results. We propose a theoretical model describing dipole interactions valid for the linear response regime to explain the observed trends. This model predicts optimum particle sizes for hyperthermia to about 30% smaller than those previously predicted, depending on the nanoparticle parameters and chain size. Also, optimum chain lengths depended on nanoparticle surface-to-surface distance. Our results might have important implications to cancer treatment and could motivate new strategies to optimize magnetic hyperthermia. PMID:24096272

  1. On the surface magnetism induced atypical ferromagnetic behavior of cerium oxide (CeO2) nanoparticles

    NASA Astrophysics Data System (ADS)

    Sakara, M.; Arumugam, S.; Tripathy, S.; Balakumar, S.

    2012-06-01

    An investigation was made on the intrinsic ferromagnetic behavior of nano sized cerium oxide (ceria). The nanosized ceria was prepared by modified sol gel method with crystallite size around 7nm. Structural analysis was done by XRD which showed a single phase, impurity free fluorite type crystal structured of nano ceria. The morphological analysis by FESEM technique showed agglomerated nature of nanoparticles due to their high surface energy. The surface and bulk information was obtained from UV and visible Raman analysis. From Raman studies it was observed that the large surface defect which was the prime reason for the induced surface magnetism in the nano ceria. From magnetization studies by VSM, it was found that if magnetism was associated with the surface defects of the material. The ferromagnetic behavior of nanosized ceria is still under debate. An attempt has taken to explain the same with emphasizing the surface magnetism of ceria nanoparticles.

  2. Inter-particle interactions and magnetism in manganese-zinc ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Poddar, P.; Srikanth, H.; Morrison, S. A.; Carpenter, E. E.

    2005-03-01

    Manganese-zinc ferrite (Mn xZn 1-xFe 2O 4) nanoparticles were synthesized by reverse micelle technique using two different surfactant media—(1) bis-(2-ethylhexl) sodium sulfosuccinate (AOT) and (2) mix of nonylphenol poly(oxyethylene) 5 and nonylphenol poly(oxyethylene) 9 (NP) followed by annealing of precursors to remove the surfactant coating and to obtain better crystalline phase. A comparison of the magnetic properties showed distinct differences in blocking temperature, coercivity and saturation magnetization. Radio-frequency (RF) transverse susceptibility (TS) measurements were in agreement with the static magnetization data. Our precise TS measurements further revealed features associated with anisotropy fields that were dependent on the grain size, crystallinity and inter-particle interactions. Overall, we have demonstrated that RF TS is an excellent probe of the dynamic magnetization and influence of effects such as crystallinity and inter-particle interactions in soft ferrite nanoparticles.

  3. Pattern Recognition of Cancer Cells Using Aptamer-Conjugated Magnetic Nanoparticles

    PubMed Central

    Bamrungsap, Suwussa; Chen, Tao; Shukoor, Mohammed Ibrahim; Chen, Zhuo; Sefah, Kwame; Chen, Yan; Tan, Weihong

    2012-01-01

    Biocompatible magnetic nanosensors based on reversible self-assembly of dispersed magnetic nanoparticles into stable nanoassemblies have been used as effective magnetic relaxation switches (MRSw) for the detection of molecular interactions. We report, for the first time, the design of MRSw based on aptamer-conjugated magnetic nanoparticles (ACMNPs). The ACMNPs capitalize on the ability of aptamers to specifically bind target cancer cells, as well as the large surface area of MNPs to accommodate multiple aptamer binding events. The ACMNPs can detect as few as 10 cancer cells in 250 ?L of sample. The ACMNPs’ specificity and sensitivity are also demonstrated by detection in cell mixtures and complex biological media, including fetal bovine serum (FBS), human plasma, and whole blood. Furthermore, by using an array of ACMNPs, various cell types can be differentiated through pattern recognition, thus creating a cellular molecular profile which will allow clinicians to accurately identify cancer cells at the molecular and single cell level. PMID:22424140

  4. Functionalized magnetic nanoparticles for sample preparation in proteomics and peptidomics analysis.

    PubMed

    Li, Yan; Zhang, Xiangmin; Deng, Chunhui

    2013-11-01

    Sample preparation is a fundamental step in the proteomics and peptidomics workflow. Due to their good biocompatibility, superparamagnetic property, and high binding capacity, magnetic nanoparticles (MNPs) functionalized with different active moieties have been widely applied in recent years in various sample preparation procedures in proteomics and peptidomics analysis. The magnetic cores of the MNPs facilitate elegant handling using only magnetic devices and their small diameters are advantageous for increasing the sensitivity when using subsequent mass spectrometry (MS) analysis or gel electrophoresis. This review mainly focuses on overviewing present advances in the preparation and application of functionalized magnetic nanoparticles for sample preparation in proteomics and peptidomics analysis, including protein digestion, enrichment of low-abundance peptides/proteins and specific enrichment of peptides/proteins with post-translational modifications, such as phosphorylation and glycosylation. PMID:23933677

  5. Antibacterial properties of Ag nanoparticle loaded multilayers and formation of magnetically directed antibacterial microparticles.

    PubMed

    Lee, Daeyeon; Cohen, Robert E; Rubner, Michael F

    2005-10-11

    Antibacterial coatings based on hydrogen-bonded multilayers containing in situ synthesized Ag nanoparticles were created on planar surfaces and on magnetic colloidal particles. We report the antibacterial properties of these coatings, determined using a disk-diffusion (Kirby-Bauer) test, as a function of the film thickness and the concentration of Ag nanoparticles in the hydrogen-bonded multilayers. The zone of inhibition (ZoI) determined by the disk-diffusion test increases as the thickness of the multilayer film is increased. Results obtained for the values of the ZoI as a function of film thickness can be described adequately with a simple diffusion model (i.e., the square of the zone of inhibition (ZoI) depended linearly on the logarithm of the thickness of the silver-loaded films). This observation suggests that, in order to incrementally increase the ZoI, an exponentially increasing amount of Ag is required within the multilayers. In general, there was no statistically significant correlation between the zone of inhibition and the number of Ag loading and reduction cycles. The duration of sustained release of antibacterial Ag ions from these coatings, however, could be prolonged by increasing the total supply of zerovalent silver in the films via multiple loading and reduction cycles. These results indicate that the release of silver is controlled by an oxidation mechanism at the surface of the nanoparticles and that repeated loading and reduction of silver leads preferentially to growth of the existing silver nanoparticles in the film as opposed to nucleation of new Ag nanoparticles. We also show that magnetic microspheres coated with silver nanoparticle loaded hydrogen-bonded multilayer thin films can be used to deliver antibacterial agents to specific locations. The minimum inhibitory concentration (MIC) of nanocomposite coated microspheres was determined by the agar dilution technique: antibacterial magnetic microspheres with higher concentrations of Ag nanoparticles exhibited lower MIC values. PMID:16207049

  6. Effect of spatial confinement on magnetic hyperthermia via dipolar interactions in Fe?O? nanoparticles for biomedical applications.

    PubMed

    Sadat, M E; Patel, Ronak; Sookoor, Jason; Bud'ko, Sergey L; Ewing, Rodney C; Zhang, Jiaming; Xu, Hong; Wang, Yilong; Pauletti, Giovanni M; Mast, David B; Shi, Donglu

    2014-09-01

    In this work, the effect of nanoparticle confinement on the magnetic relaxation of iron oxide (Fe3O4) nanoparticles (NP) was investigated by measuring the hyperthermia heating behavior in high frequency alternating magnetic field. Three different Fe3O4 nanoparticle systems having distinct nanoparticle configurations were studied in terms of magnetic hyperthermia heating rate and DC magnetization. All magnetic nanoparticle (MNP) systems were constructed using equivalent ~10nm diameter NP that were structured differently in terms of configuration, physical confinement, and interparticle spacing. The spatial confinement was achieved by embedding the Fe3O4 nanoparticles in the matrices of the polystyrene spheres of 100 nm, while the unconfined was the free Fe3O4 nanoparticles well-dispersed in the liquid via PAA surface coating. Assuming the identical core MNPs in each system, the heating behavior was analyzed in terms of particle freedom (or confinement), interparticle spacing, and magnetic coupling (or dipole-dipole interaction). DC magnetization data were correlated to the heating behavior with different material properties. Analysis of DC magnetization measurements showed deviation from classical Langevin behavior near saturation due to dipole interaction modification of the MNPs resulting in a high magnetic anisotropy. It was found that the Specific Absorption Rate (SAR) of the unconfined nanoparticle systems were significantly higher than those of confined (the MNPs embedded in the polystyrene matrix). This increase of SAR was found to be attributable to high Néel relaxation rate and hysteresis loss of the unconfined MNPs. It was also found that the dipole-dipole interactions can significantly reduce the global magnetic response of the MNPs and thereby decrease the SAR of the nanoparticle systems. PMID:25063092

  7. Effect of spatial confinement on magnetic hyperthermia via dipolar interactions in Fe3O4 nanoparticles for biomedical applications

    SciTech Connect

    Sadat, M E [University of Cincinnati; Patel, Ronak [University of Cincinnati; Sookoor, Jason [University of Cincinnati; Bud'ko, Sergey L [Ames Laboratory; Ewing, Rodney C [Stanford University; Zhang, Jiaming [Stanford University; Xu, Hong [Shanghai Jiao Tong University; Wang, Yilong [Tongji University School of Medicine; Pauletti, Giovanni M [University of Cincinnati; Mast, David B [University of Cincinnati; Shi, Donglu [University of Cincinnati

    2014-09-01

    In this work, the effect of nanoparticle confinement on the magnetic relaxation of iron oxide (Fe3O4) nanoparticles (NP) was investigated by measuring the hyperthermia heating behavior in high frequency alternating magnetic field. Three different Fe3O4 nanoparticle systems having distinct nanoparticle configurations were studied in terms of magnetic hyperthermia heating rate and DC magnetization. All magnetic nanoparticle (MNP) systems were constructed using equivalent ~10nm diameter NP that were structured differently in terms of configuration, physical confinement, and interparticle spacing. The spatial confinement was achieved by embedding the Fe3O4 nanoparticles in the matrices of the polystyrene spheres of 100 nm, while the unconfined was the free Fe3O4 nanoparticles well-dispersed in the liquid via PAA surface coating. Assuming the identical core MNPs in each system, the heating behavior was analyzed in terms of particle freedom (or confinement), interparticle spacing, and magnetic coupling (or dipole-dipole interaction). DC magnetization data were correlated to the heating behavior with different material properties. Analysis of DC magnetization measurements showed deviation from classical Langevin behavior near saturation due to dipole interaction modification of the MNPs resulting in a high magnetic anisotropy. It was found that the Specific Absorption Rate (SAR) of the unconfined nanoparticle systems were significantly higher than those of confined (the MNPs embedded in the polystyrene matrix). This increase of SAR was found to be attributable to high Néel relaxation rate and hysteresis loss of the unconfined MNPs. It was also found that the dipole-dipole interactions can significantly reduce the global magnetic response of the MNPs and thereby decrease the SAR of the nanoparticle systems.

  8. Applications of exchange coupled bi-magnetic hard/soft and soft/hard magnetic core/shell nanoparticles

    NASA Astrophysics Data System (ADS)

    López-Ortega, Alberto; Estrader, Marta; Salazar-Alvarez, German; Roca, Alejando G.; Nogués, Josep

    2015-02-01

    The applications of exchange coupled bi-magnetic hard/soft and soft/hard ferromagnetic core/shell nanoparticles are reviewed. After a brief description of the main synthesis approaches and the core/shell structural-morphological characterization, the basic static and dynamic magnetic properties are presented. Five different types of prospective applications, based on diverse patents and research articles, are described: permanent magnets, recording media, microwave absorption, biomedical applications and other applications. Both the advantages of the core/shell morphology and some of the remaining challenges are discussed.

  9. Design and fabrication of magnetic nanoparticles for targeted drug delivery and imaging

    PubMed Central

    Veiseh, Omid; Gunn, Jonathan; Zhang, Miqin

    2009-01-01

    Magnetic nanoparticles (MNPs) represent a class of non-invasive imaging agents that have been developed for magnetic resonance (MR) imaging. These MNPs have traditionally been used for disease imaging via passive targeting, but recent advances have opened the door to cellular-specific targeting, drug delivery, and multi-modal imaging by these nanoparticles. As more elaborate MNPs are envisioned, adherence to proper design criteria (e.g. size, coating, molecular functionalization) becomes even more essential. This review summarizes the design parameters that affect MNP performance in vivo, including the physicochemical properties and nanoparticle surface modifications, such as MNP coating and targeting ligand functionalizations that can enhance MNP management of biological barriers. A careful review of the chemistries used to modify the surfaces of MNPs is also given, with attention paid to optimizing the activity of bound ligands while maintaining favorable physicochemical properties. PMID:19909778

  10. Magnetic and nonmagnetic nanoparticles from a group of uniform materials based on organic salts.

    PubMed

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

    2009-10-27

    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 degrees C), while others have melting points above the conventional 100 degrees 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 particles ranging from 14 to 198 nm were achieved by manipulation of the reagent concentration, for example. Controllable formation of this new breed of nanoparticles is important for numerous potential applications and will open up interesting new opportunities in drug delivery, magnetic resonance imaging, and protein separations, among other areas. PMID:19780529

  11. Nano-objects for addressing the control of nanoparticle arrangement and performance in magnetic hyperthermia.

    PubMed

    Andreu, Irene; Natividad, Eva; Solozábal, Laura; Roubeau, Olivier

    2015-02-24

    One current challenge of magnetic hyperthermia is achieving therapeutic effects with a minimal amount of nanoparticles, for which improved heating abilities are continuously pursued. However, it is demonstrated here that the performance of magnetite nanocubes in a colloidal solution is reduced by 84% when they are densely packed in three-dimensional arrangements similar to those found in cell vesicles after nanoparticle internalization. This result highlights the essential role played by the nanoparticle arrangement in heating performance, uncontrolled in applications. A strategy based on the elaboration of nano-objects able to confine nanocubes in a fixed arrangement is thus considered here to improve the level of control. The obtained specific absorption rate results show that nanoworms and nanospheres with fixed one- and two-dimensional nanocube arrangements, respectively, succeed in reducing the loss of heating power upon agglomeration, suggesting a change in the kind of nano-object to be used in magnetic hyperthermia. PMID:25658023

  12. Impulsion of induced magnetic field for Brownian motion of nanoparticles in peristalsis

    NASA Astrophysics Data System (ADS)

    Akbar, Noreen Sher; Raza, M.; Ellahi, R.

    2015-05-01

    In the present study, we examined the effect of induced magnetic field for the peristaltic flow of four different nanoparticles with the base fluid water in the presence of Brownian motion, in a vertical asymmetric channel. The mathematical formulation is presented. Exact solutions have been evaluated for the resulting equations. The obtained expressions for velocity, temperature, pressure gradient and magnetic force function are described through graphs for various pertinent parameters. The streamlines are drawn for some physical quantities to discuss the trapping phenomenon.

  13. Liquid-crystalline elastomer-nanoparticle hybrids with reversible switch of magnetic memory.

    PubMed

    Haberl, Johannes M; Sánchez-Ferrer, Antoni; Mihut, Adriana M; Dietsch, Hervé; Hirt, Ann M; Mezzenga, Raffaele

    2013-03-25

    A stimuli-responsive material is synthesized that combines the actuation potential of liquid-crystalline elastomers with the anisotropic magnetic properties of ellipsoidal iron oxide nanoparticles. The resulting nanocomposite exhibits unique shape-memory features with magnetic information, which can be reversibly stored and erased via parameters typical of soft materials, such as high deformations, low stresses, and liquid-crystalline smectic-isotropic transition temperatures. PMID:23359417

  14. Magnetic properties and formation of Sr ferrite nanoparticle and Zn, Ti\\/Ir substituted phases

    Microsoft Academic Search

    Qingqing Fang; Yanmei Liu; Ping Yin; Xiaoguang Li

    2001-01-01

    Strontium hexaferrite nanoparticles are prepared by the chemical sol–gel route. Specific saturation magnetization ?s and coercive field strength Hc are determined depending on the heat treatment of the gel and iron\\/strontium ratio in the starting solution. These ultrafine powders with single-domain behavior have specific saturation magnetization ?s=74emu\\/g and coercive field strength Hc=6.4kOe. Experimental results show that it is necessary to

  15. Biocompatible surfactin-stabilized superparamagnetic iron oxide nanoparticles as contrast agents for magnetic resonance imaging

    Microsoft Academic Search

    Zhenyu Liao; Hanjie Wang; Xiaodong Wang; Chunling Wang; Xiufeng Hu; Xiaohong Cao; Jin Chang

    2010-01-01

    We have reported the ability of Bacillus natto TK-1 to produce surfactin which shows strong antitumor activity and appears less toxic to the normal cells. This report describes the use of the natural surfactin to stabilize superparamagnetic iron oxide nanoparticles (SPION) which can serve as a sensitive contrast agent for magnetic resonance imaging (MRI). The results showed that the organic

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

    E-print Network

    Dunin-Borkowski, Rafal E.

    Calixarene-stabilised cobalt nanoparticle rings: Self-assembly and collective magnetic properties 10 October 2008) Calixarenes can be used to promote the self-assembly of thermoremanent cobalt. This strategy was used many years ago using ferrite memory cores for data registry (2, 3), prior to the advent

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

    E-print Network

    Volinsky, Alex A.

    synthesis [8], microemulsion [9], chemical co-precipitation [10], oxidation of Fe (OH)2 by H2O2 [11], R and collected. An appropriate amount of hydrogen peroxide (H2O2) was added to the filtrate so that all ironFe3O4 magnetic nanoparticles synthesis from tailings by ultrasonic chemical co-precipitation Shen

  18. Electronic and Magnetic Structure of Fe Nanoparticle Embedded in FeAl

    NASA Astrophysics Data System (ADS)

    Wang, Yang; Stocks, G. Malcolm; Rusanu, Aurelian; Nicholson, Don M. C.; Eisenbach, Markus; Faulkner, J. S.

    2006-03-01

    Magnetic nanostructures are of great scientific interest because of their potential applications in a wide range of technologies - data storage, magneto-electronics, permanent magnets, smart drug delivery, etc. Unfortunately magnetic nanostructures present substantial theoretical challenges due to the need to treat the electronic interactions quantum mechanically whilst dealing with a, still, large number of atoms. In this presentation, we discuss our recent studies of magnetic nanoparticles using the Locally Self-consistent Multiple Scattering (LSMS) method, an order-N ab initio method capable of treating tens of thousands of atoms. In particular, we show results for a Fe nanoparticle embedded in a stoichiometric B2-FeAl binary alloy. The Fe nanoparticle, has the shape of a BCC Wigner-Seitz cell, contains 4,409 Fe atoms, and measures about 5 nm across the diagonal corners. Including the surrounding matrix the calculation involves 16,000 atoms. We show results for the moment and charge distribution within nanoparticle, on the facets, and in the FeAl matrix.

  19. Nanoparticle-DNA-polymer composites for hepatocellular carcinoma cell labeling, sensing, and magnetic resonance imaging.

    PubMed

    Leung, Ken Cham-Fai; Lee, Siu-Fung; Wong, Chi-Hin; Chak, Chun-Pong; Lai, Josie M Y; Zhu, Xiao-Ming; Wang, Yi-Xiang J; Sham, Kathy W Y; Cheng, Christopher H K

    2013-12-15

    This paper describes comparative studies and protocols in (1) self-assembling of ultrasmall superparamagnetic iron oxide nanoparticle (NP), circular plasmid DNA, and branched polyethylenimine (PEI) composites; (2) magnetofection; (3) gene delivery, (4) magnetic resonance imaging (MRI), and (5) cytotoxicity of the composites toward hepatocellular carcinoma HepG2 cells. PMID:23811300

  20. Structural, magnetic, dielectric and optical properties of nickel ferrite nanoparticles synthesized by co-precipitation method

    NASA Astrophysics Data System (ADS)

    Joshi, Seema; Kumar, Manoj; Chhoker, Sandeep; Srivastava, Geetika; Jewariya, Mukesh; Singh, V. N.

    2014-11-01

    Nickel ferrite nanoparticles were synthesized by wet chemical co-precipitation method and the corresponding temperature dependent structural, magnetic and optical properties of these nanoparticles have been investigated. X-ray diffraction patterns show the single phase cubic spinal crystal structure belonging to the space group Fd3m. The average crystallite size varies in the range 8-20 nm with varying sintering temperature. Raman spectroscopy exhibits a doublet-like peak behaviour which indicates the presence of mixed spinel structure. The saturation magnetization, coercivity and remanence increase with increasing sintering temperature from 250 to 550 °C. The non-saturation and low values of magnetization at high fields indicate the strong surface effects to magnetization in NiFe2O4 nanoparticles. The g-value calculated from electron spin resonance spectrum indicates the transfer of divalent metallic ion from octahedral to tetrahedral site (i.e. mixed spinel structure). The dielectric permittivity, loss tangent and ac conductivity measurements show strong temperature dependence at all frequencies. The observed ac conductivity response suggests that the conduction in ferrite nanoparticles is due to feeble polaron hopping between Fe3+/Fe2+ ions. Room temperature UV-vis diffuse spectra indicate that NiFe2O4 is an indirect band gap material with band gap ranges from 1.27 to 1.47 eV with varying sintering temperature. The photoluminescence study clearly indicates that the Ni2+ ions occupy both octahedral and tetrahedral sites confirming mixed spinel structure.

  1. Catalytically active bovine serum amine oxidase bound to fluorescent and magnetically drivable nanoparticles

    PubMed Central

    Sinigaglia, Giulietta; Magro, Massimiliano; Miotto, Giovanni; Cardillo, Sara; Agostinelli, Enzo; Zboril, Radek; Bidollari, Eris; Vianello, Fabio

    2012-01-01

    Novel superparamagnetic surface-active maghemite nanoparticles (SAMNs) characterized by a diameter of 10 ± 2 nm were modified with bovine serum amine oxidase, which used rhodamine B isothiocyanate (RITC) adduct as a fluorescent spacer-arm. A fluorescent and magnetically drivable adduct comprised of bovine serum copper-containing amine oxidase (SAMN–RITC–BSAO) that immobilized on the surface of specifically functionalized magnetic nanoparticles was developed. The multifunctional nanomaterial was characterized using transmission electron microscopy, infrared spectroscopy, mass spectrometry, and activity measurements. The results of this study demonstrated that bare magnetic nanoparticles form stable colloidal suspensions in aqueous solutions. The maximum binding capacity of bovine serum amine oxidase was approximately 6.4 mg g?1 nanoparticles. The immobilization procedure reduced the catalytic activity of the native enzyme to 30% ± 10% and the Michaelis constant was increased by a factor of 2. We suggest that the SAMN–RITC–BSAO complex, characterized by a specific activity of 0.81 IU g?1, could be used in the presence of polyamines to create a fluorescent magnetically drivable H2O2 and aldehydes-producing system. Selective tumor cell destruction is suggested as a potential future application of this system. PMID:22619559

  2. Internal magnetic field effects on the photochemistry of a xanthone derivate covalently anchored to magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Alvaro, Mercedes; Cabeza, Jose F.; Carbonell, Esther; Garcia, Hermenegildo

    2005-07-01

    Irradiation of azaxanthone in the presence of colloidal magnetite nanoparticles gives rise to the generation of the corresponding azaxanthone triplet, whose lifetime is influenced by internal magnetic field effects. In contrast, covalent tethering between magnetite and azaxanthone promotes photoinduced electron transfer leading to the observation of azaxanthone radical anion.

  3. Iron oxide nanoparticle encapsulated diatoms for magnetic delivery of small molecules to tumors.

    PubMed

    Todd, Trever; Zhen, Zipeng; Tang, Wei; Chen, Hongmin; Wang, Geoffrey; Chuang, Yen-Jun; Deaton, Kayley; Pan, Zhengwei; Xie, Jin

    2014-02-21

    Small molecules can be co-loaded with iron oxide nanoparticles onto diatoms. With an external magnetic field, the diatoms, after systemic administration, can be attracted to tumors. This study suggests a great potential of diatoms as a novel and powerful therapeutic vehicle. PMID:24424277

  4. Catalytically active bovine serum amine oxidase bound to fluorescent and magnetically drivable nanoparticles.

    PubMed

    Sinigaglia, Giulietta; Magro, Massimiliano; Miotto, Giovanni; Cardillo, Sara; Agostinelli, Enzo; Zboril, Radek; Bidollari, Eris; Vianello, Fabio

    2012-01-01

    Novel superparamagnetic surface-active maghemite nanoparticles (SAMNs) characterized by a diameter of 10 ± 2 nm were modified with bovine serum amine oxidase, which used rhodamine B isothiocyanate (RITC) adduct as a fluorescent spacer-arm. A fluorescent and magnetically drivable adduct comprised of bovine serum copper-containing amine oxidase (SAMN-RITC-BSAO) that immobilized on the surface of specifically functionalized magnetic nanoparticles was developed. The multifunctional nanomaterial was characterized using transmission electron microscopy, infrared spectroscopy, mass spectrometry, and activity measurements. The results of this study demonstrated that bare magnetic nanoparticles form stable colloidal suspensions in aqueous solutions. The maximum binding capacity of bovine serum amine oxidase was approximately 6.4 mg g(-1) nanoparticles. The immobilization procedure reduced the catalytic activity of the native enzyme to 30% ± 10% and the Michaelis constant was increased by a factor of 2. We suggest that the SAMN-RITC-BSAO complex, characterized by a specific activity of 0.81 IU g(-1,) could be used in the presence of polyamines to create a fluorescent magnetically drivable H(2)O(2) and aldehydes-producing system. Selective tumor cell destruction is suggested as a potential future application of this system. PMID:22619559

  5. Interparticle interaction effects on magnetic behaviors of hematite (?-Fe2O3) nanoparticles

    NASA Astrophysics Data System (ADS)

    Can, Musa Mutlu; F?rat, Tezer; Özcan, ?adan

    2011-07-01

    The interparticle magnetic interactions of hematite (?-Fe2O3) nanoparticles were investigated by temperature and magnetic field dependent magnetization curves. The synthesis were done in two steps; milling metallic iron (Fe) powders in pure water (H2O), known as mechanical milling technique, and annealing at 600 °C. The crystal and molecular structure of prepared samples were determined by X-ray powder diffraction (XRD) spectra and Fourier transform infrared (FTIR) spectra results. The average particle sizes and the size distributions were figured out using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The magnetic behaviors of ?-Fe2O3 nanoparticles were analyzed with a vibrating sample magnetometer (VSM). As a result of the analysis, it was observed that the prepared ?-Fe2O3 nanoparticles did not perform a sharp Morin transition (the characteristic transition of ?-Fe2O3) due to lack of unique particle size distribution. However, the transition can be observed in the wide temperature range as “a continuously transition”. Additionally, the effect of interparticle interaction on magnetic behavior was determined from the magnetization versus applied field (?(M)) curves for 26±2 nm particles, dispersed in sodium oxalate matrix under ratios of 200:1, 300:1, 500:1 and 1000:1. The interparticle interaction fields, recorded at 5 K to avoid the thermal interactions, were found as ?1082 Oe for 26±2 nm particles.

  6. Submicrometer Hall sensors for detection of magnetic nanoparticles in biomolecular sensing

    NASA Astrophysics Data System (ADS)

    Mihajlovic, Goran; Xiong, P.; von Molnar, S.; Ohtani, K.; Ohno, H.; Field, M.; Sullivan, G. J.

    2006-03-01

    Significant progress has been made in the recent years in synthesis and biomolecular functionalization of magnetic nanoparticles. These magnetic bio-nanolabels can be utilized as protein or gene markers in biomolecular sensing assays, in contrast to the much larger micron sized magnetic beads that are usually limited to cell labeling. However, the low magnetic moments of individual nanoparticles (10^4-10^5 ?B) render their sensitive detection still a challenging task. In order to address this issue we are developing miniaturized Hall sensors from InAs/AlSb quantum well semiconductor heterostructures with active Hall cross areas down to 300 nm x 300 nm. Our preliminary characterization measurements performed at room temperature show functional devices with magnetic field resolution < 100 ?T/?Hz at frequencies above 100 Hz, yielding a moment sensitivity ˜ 10^5 ?B. In addition to the progress in improving the moment sensitivity of the submicrometer Hall detectors, we will also present efforts in device integration with on-chip microcoils for the generation of local magnetic excitation fields. Results on nanoparticle detection will also be presented.

  7. Magnetic nanoparticle-peptide conjugates for in vitro and in vivo targeting and extraction of cancer cells.

    PubMed

    Scarberry, Kenneth E; Dickerson, Erin B; McDonald, John F; Zhang, Z John

    2008-08-01

    Magnetic cobalt spinel ferrite nanoparticles coated with biocompatible polygalacturonic acid were functionalized with ligands specific for targeting expressed EphA2 receptors on ovarian cancer cells. By using such magnetic nanoparticle-peptide conjugates, targeting and extraction of malignant cells were achieved with a magnetic field. Targeting ovarian cancer cells with receptor specific peptide-modified magnetic nanoparticles resulted in cell capture from a flow stream in vitro and from the peritoneal cavity of mice in vivo. Successful removal of metastatic cancer cells from the abdominal cavity and circulation using magnetic nanoparticle conjugates indicate the feasibility of a dialysis-like treatment and may improve long-term survival rates of ovarian cancer patients. This approach can be applied for fighting other cancers, such as leukemia, once the receptors on malignant cells are identified and the efficacy of targeting ligands is established. PMID:18611005

  8. Enhanced magnetic behaviors of CoPt nanoparticles by addition of SiO{sub 2}

    SciTech Connect

    Wang, Yaxin; Zhang, Xiaolong; Liu, Yang; Jiang, Yuhong [Institute of Condensed State Physics, Jilin Normal University, Siping 136000 (China); Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University (China); Zhang, Yongjun, E-mail: zhangyongjunwyx@126.com [Institute of Condensed State Physics, Jilin Normal University, Siping 136000 (China); Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University (China); Yang, Jinghai [Institute of Condensed State Physics, Jilin Normal University, Siping 136000 (China); Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University (China)

    2014-05-01

    Equiatomic L1{sub 0} CoPt alloy nanoparticles (NPs) with various contents of SiO{sub 2} are synthesized by the simple sol–gel method. The SiO{sub 2} additions restrain the growth of grain and hinder the agglomeration formation. The coercivity increases first and then decreases with SiO{sub 2} addition. Compared to the 0 ?l-SiO{sub 2} CoPt NPs, the higher ordering degree and better magnetic properties are obtained by the addition of amount 10 ?l SiO{sub 2} in our sample. And the coercivity is two times as large as that of 0 ?l-SiO{sub 2} NPs. When the addition of SiO{sub 2} is more than 10 ?l, the deteriorated magnetic properties are ascribed to the transformation from hard magnetically phase to soft magnetically phase due to the decrease of particle size. - Graphical abstract: L1{sub 0} CoPt alloy nanoparticles with various contents of SiO{sub 2} are synthesized by sol–gel method. The effects of SiO{sub 2} on the structure and magnetic properties of CoPt nanoparticles are investigated. - Highlights: • The L1{sub 0} CoPt–SiO{sub 2} nanoparticles (NPs) were synthesized by sol–gel method. • Effects of SiO{sub 2} content on the structure and magnetic properties were investigated. • The addition of SiO{sub 2} restrained the growth of particle size. • CoPt–10 ?l SiO{sub 2} NPs showed a higher ordering degree and better magnetic properties.

  9. Voltage control of magnetic hysteresis in a nickel nanoparticle

    NASA Astrophysics Data System (ADS)

    Gartland, P.; Jiang, W.; Davidovi?, D.

    2015-06-01

    The effects of voltage bias on magnetic hysteresis in single Ni particles 2 to 3 nm in diameter are measured between temperatures of 60 mK and 4.2 K by using sequential electron tunneling through the particle. While some Ni particles do not display magnetic hysteresis in tunneling current versus magnetic field, in the Ni particles that display hysteresis, the effect of bias voltage on magnetic switching field is nonlinear. The magnetic switching field changes weakly in the voltage interval ˜1 mV above the tunneling onset voltage, and rapidly decreases versus voltage above that interval. A voltage-driven mechanism explaining this nonlinear suppression of magnetic hysteresis is presented, where the key effect is a magnetization blockade due to the addition of spin-orbit anisotropy ?so to the particle by a single electron. A necessary condition for the particle to exhibit magnetization blockade is that ?so increases when the magnetization is slightly displaced from the easy axis. In that case, an electron will be energetically unable to access the particle if the magnetization is sufficiently displaced from the easy axis, which leads to a voltage interval where magnetic hysteresis is possible that is comparable to ?so/e , where e is the electronic charge. If ?so decreases vs magnetization displacement from the easy axis, there is no magnetization blockade and no hysteresis.

  10. Multi-photon excited luminescence of magnetic FePt core-shell nanoparticles

    PubMed Central

    Seemann, K.M.; Kuhn, B.

    2014-01-01

    We present magnetic FePt nanoparticles with a hydrophilic, inert, and biocompatible silico-tungsten oxide shell. The particles can be functionalized, optically detected, and optically manipulated. To show the functionalization the fluorescent dye NOPS was bound to the FePt core-shell nanoparticles with propyl-triethoxy-silane linkers and fluorescence of the labeled particles were observed in ethanol (EtOH). In aqueous dispersion the NOPS fluorescence is quenched making them invisible using 1-photon excitation. However, we observe bright luminescence of labeled and even unlabeled magnetic core-shell nanoparticles with multi-photon excitation. Luminescence can be detected in the near ultraviolet and the full visible spectral range by near infrared multi-photon excitation. For optical manipulation, we were able to drag clusters of particles, and maybe also single particles, by a focused laser beam that acts as optical tweezers by inducing an electric dipole in the insulated metal nanoparticles. In a first application, we show that the luminescence of the core-shell nanoparticles is bright enough for in vivo multi-photon imaging in the mouse neocortex down to cortical layer 5. PMID:25071977

  11. Detection of low-concentration superparamagnetic nanoparticles using an integrated radio frequency magnetic biosensor

    NASA Astrophysics Data System (ADS)

    Devkota, J.; Wang, C.; Ruiz, A.; Mohapatra, S.; Mukherjee, P.; Srikanth, H.; Phan, M. H.

    2013-03-01

    Improving the sensitivity of existing biosensors for highly sensitive detection of magnetic nanoparticles as biomarkers in biological systems is an important and challenging task. Here, we propose a method of combining the magneto-resistance (MR), magneto-reactance (MX), and magneto-impedance (MI) effects to develop an integrated magnetic biosensor with tunable and enhanced sensitivity. A systematic study of the 7 nm Fe3O4 nanoparticle concentration dependence of MR, MX, and MI ratios of a soft ferromagnetic amorphous ribbon shows that these ratios first increase sharply with increase in particle concentration (0-124 nM) and then remain almost unchanged for higher concentrations (124 nM-1240 nM). The MX-based biosensor shows the highest sensitivity. With this biosensor, ˜2.1 × 1011 7 nm Fe3O4 nanoparticles can be detected over a detection area of 2.0 × 105 ?m2, which is comparable to a superconducting quantum interference device biosensor that detects the presence of ˜1 × 108 11 nm Fe3O4 nanoparticles over a detection area of 6.8 × 104 ?m2. The proposed biosensor can detect low and various concentrations of superparamagnetic nanoparticles (below 10 nm in size), which is of practical importance in biosensing applications.

  12. Magnetic properties of Fe-oxide and (Fe, Co) oxide nanoparticles synthesized in polystyrene resin matrix

    NASA Astrophysics Data System (ADS)

    Rodak, D.; Kroll, E.; Tsoi, G. M.; Vaishnava, P. P.; Naik, R.; Wenger, L. E.; Suryanarayanan, R.; Naik, V. M.; Boolchand, P.

    2003-03-01

    Magnetic nanoparticles have potential applications ranging from drug delivery and imaging in the medical field to sensing and memory storage in technology. The preparation, structure, and physical properties of iron oxide-based nanoparticles synthesized by ion exchange in a polystyrene resin matrix have been investigated. Employing a synthesis method developed originally by Ziolo, et. al^1, nanoparticles were prepared in a sulfonated divinyl benzene polystyrene resin matrix using various aqueous solutions of (1) FeCl_2, (2) FeCl_3, (3) FeCl2 : 2FeCl3 , (4) 9FeCl2 : CoCl_2, and (5) 4FeCl2 : CoCl_2. Powder x-ray diffraction measurements were used to identify the phases present while transmission electron microscopy was used for particle size distribution determinations. SQUID magnetization measurements (field-cooled and zero-field-cooled) and Fe^57 Mössbauer effect measurements indicate the presence of ferromagnetic iron oxide phases and a superparamagnetic behavior with blocking temperatures (T_B) varying from 50 K to room temperature. Nanoparticles synthesized using a stoichiometric mixture of FeCl2 and FeCl3 exhibit the lowest TB and smallest particle size distribution. The Mössbauer effect measurements have also been used to identify the iron oxides phases present and their relative amounts in the nanoparticles ^1R.F. Ziolo, et al., Science 207, 219 (1992). *Permanent address: Kettering University, Flint, MI 48504

  13. A highly sensitive magnetic biosensor for detection and quantification of anticancer drugs tagged to superparamagnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Devkota, J.; Wingo, J.; Mai, T. T. T.; Nguyen, X. P.; Huong, N. T.; Mukherjee, P.; Srikanth, H.; Phan, M. H.

    2014-05-01

    We report on a highly sensitive magnetic biosensor based on the magneto-reactance (MX) effect of a Co65Fe4Ni2Si15B14 amorphous ribbon with a nanohole-patterned surface for detection and quantification of anticancer drugs (Curcumin) tagged to superparamagnetic (Fe3O4) nanoparticles. Fe3O4 nanoparticles (mean size, ˜10 nm) were first coated with Alginate, and Curcumin was then tagged to the nanoparticles. The detection and quantification of Curcumin were assessed by the change in MX of the ribbon subject to varying concentrations of the Fe3O4 nanoparticles to which Curcumin was tagged. A high capacity of the MX-based biosensor in quantitative analysis of Curcumin-loaded Fe3O4 nanoparticles was achieved in the range of 0-50 ng/ml, beyond which the detection sensitivity of the sensor remained unchanged. The detection sensitivity of the biosensor reached an extremely high value of 30%, which is about 4-5 times higher than that of a magneto-impedance (MI) based biosensor. This biosensor is well suited for detection of low-concentration magnetic biomarkers in biological systems.

  14. A quantitative design and analysis of magnetic nanoparticle heating systems

    E-print Network

    Khushrushahi, Shahriar Rohinton

    2006-01-01

    Magnetic particles under the influence of an alternating magnetic field act as localized heating sources due to various loss mechanisms. This effect has been extensively investigated in hypothermia studies over the past ...

  15. In situ synthesis of plate-like Fe 2 O 3 nanoparticles in porous cellulose films with obvious magnetic anisotropy

    Microsoft Academic Search

    Shilin Liu; Jinping Zhou; Lina Zhang

    2011-01-01

    Nanocomposite cellulose films with obvious magnetic anisotropy have been prepared by in situ synthesis of plate-like Fe2O3 nanoparticles in the cellulose matrix. The influence of the concentrations of FeCl2 and FeCl3 solutions on the morphology and particle size of the synthesized Fe2O3 nanoparticles as well as on the properties of the composite films has been investigated. The Fe2O3 nanoparticles synthesized

  16. Bismuth labeling for the CT assessment of local administration of magnetic nanoparticles.

    PubMed

    Veintemillas-Verdaguer, S; Luengo, Y; Serna, C J; Andrés-Vergés, M; Varela, M; Calero, Macarena; Lazaro-Carrillo, Ana; Villanueva, Angeles; Sisniega, A; Montesinos, P; Morales, M P

    2015-03-27

    Many therapeutic applications of magnetic nanoparticles involve the local administration of nanometric iron oxide based materials as seeds for magnetothermia or drug carriers. A simple and widespread way of controlling the process using x-ray computed tomography (CT) scanners is desirable. The combination of iron and bismuth in one entity will increase the atenuation of x-rays, offering such a possibility. In order to check this possibility core-shell nanocrystals of iron oxide@bismuth oxide have been synthesized by an aqueous route and stabilized in water by polyethylene glycol (PEG), and we have evaluated their ability to generate contrast by CT and magnetic resonance imaging (MRI) to measure the radiopacity and proton relaxivities using phantoms. High-resolution scanning transmission electron microscopy (STEM) revealed that the material consists of a highly crystalline 8 nm core of maghemite and a 1 nm shell of bismuth atoms either isolated or clustered on the nanocrystal's surface. The comparison of ?CT and MRI images of mice acquired in the presence of the contrast shows that when local accumulations of the magnetic nanoparticles take place, CT images are more superior in the localization of the magnetic nanoparticles than MRI images, which results in magnetic field inhomogeneity artifacts. PMID:25760138

  17. Initiation of shape-memory effect by inductive heating of magnetic nanoparticles in thermoplastic polymers

    PubMed Central

    Mohr, R.; Kratz, K.; Weigel, T.; Lucka-Gabor, M.; Moneke, M.; Lendlein, A.

    2006-01-01

    In shape-memory polymers, changes in shape are mostly induced by heating, and exceeding a specific switching temperature, Tswitch. If polymers cannot be warmed up by heat transfer using a hot liquid or gaseous medium, noncontact triggering will be required. In this article, the magnetically induced shape-memory effect of composites from magnetic nanoparticles and thermoplastic shape-memory polymers is introduced. A polyetherurethane (TFX) and a biodegradable multiblock copolymer (PDC) with poly(p-dioxanone) as hard segment and poly(?-caprolactone) as soft segment were investigated as matrix component. Nanoparticles consisting of an iron(III)oxide core in a silica matrix could be processed into both polymers. A homogeneous particle distribution in TFX could be shown. Compounds have suitable elastic and thermal properties for the shape-memory functionalization. Temporary shapes of TFX compounds were obtained by elongating at increased temperature and subsequent cooling under constant stress. Cold-drawing of PDC compounds at 25°C resulted in temporary fixation of the mechanical deformation by 50–60%. The shape-memory effect of both composite systems could be induced by inductive heating in an alternating magnetic field (f = 258 kHz; H = 30 kA·m?1). The maximum temperatures achievable by inductive heating in a specific magnetic field depend on sample geometry and nanoparticle content. Shape recovery rates of composites resulting from magnetic triggering are comparable to those obtained by increasing the environmental temperature. PMID:16537442

  18. Initiation of shape-memory effect by inductive heating of magnetic nanoparticles in thermoplastic polymers.

    PubMed

    Mohr, R; Kratz, K; Weigel, T; Lucka-Gabor, M; Moneke, M; Lendlein, A

    2006-03-01

    In shape-memory polymers, changes in shape are mostly induced by heating, and exceeding a specific switching temperature, T(switch). If polymers cannot be warmed up by heat transfer using a hot liquid or gaseous medium, noncontact triggering will be required. In this article, the magnetically induced shape-memory effect of composites from magnetic nanoparticles and thermoplastic shape-memory polymers is introduced. A polyetherurethane (TFX) and a biodegradable multiblock copolymer (PDC) with poly(p-dioxanone) as hard segment and poly(epsilon-caprolactone) as soft segment were investigated as matrix component. Nanoparticles consisting of an iron(III)oxide core in a silica matrix could be processed into both polymers. A homogeneous particle distribution in TFX could be shown. Compounds have suitable elastic and thermal properties for the shape-memory functionalization. Temporary shapes of TFX compounds were obtained by elongating at increased temperature and subsequent cooling under constant stress. Cold-drawing of PDC compounds at 25 degrees C resulted in temporary fixation of the mechanical deformation by 50-60%. The shape-memory effect of both composite systems could be induced by inductive heating in an alternating magnetic field (f = 258 kHz; H = 30 kA x m(-1)). The maximum temperatures achievable by inductive heating in a specific magnetic field depend on sample geometry and nanoparticle content. Shape recovery rates of composites resulting from magnetic triggering are comparable to those obtained by increasing the environmental temperature. PMID:16537442

  19. Quantification of magnetic nanoparticles with broadband measurements of magnetic susceptibility in the frequency domain

    NASA Astrophysics Data System (ADS)

    Kodama, Kazuto; An, Zhisheng; Chang, Hong; Qiang, Xiaoke

    2015-04-01

    Measurement of low-field magnetic susceptibility over a wide band of frequencies spanning four orders of magnitude is a useful method for the assessment of the grain size distribution of ultrafine magnetic particles smaller than the SP/SSD boundary. This method has been applied to a loess/paleosol sequence at Luochuan in the Chinese Loess Plateau. The studied succession consists of sequences from the latest paleosol unit to the upper part of the loess unit, spanning the last glacial-interglacial cycle. Reconstructed grain size distributions (GSDs) consist of volume fractions on the order of 10-24 m3, and the mean GSDs are modal but with distinctive skewness among the loess, the weakly developed paleosol (weak paleosol), and the mature paleosol. This indicates that the mean volume of SP particles in this sequence tends to increase during the transition from the loess to the paleosol. An index, defined as the difference between ?130 at the lowest (130 Hz) and ?500k at the highest (500 kHz) frequencies normalized to ?130, is judged to be a more suitable index than previous frequency dependence parameters for the concentration of SP particles. This index has a strong correlation with ?130, showing a continuous 'growth curve' with the rate of increase being highest for the loess, moderate for the weak paleosol, and saturated for the paleosol. The characteristic curve suggests that smaller SP particles are preferentially formed in the earlier stage of pedogenesis rather than the later phase when even larger particles are formed in the mature paleosol. These results demonstrate that the broad-band-frequency susceptibility measurement will be useful for the quantitative assessment of magnetic nanoparticles in soils and sediments. Additionally, we point out that the measurement in the frequency domain generally requires time and may not be most suitable to routine measurements. We thus propose an alternative manner, the measurement in the time domain that can be performed by measurement of transient magnetization induced by a pulsed field. Results from preliminary measurements, coupled with simulation based on the linear response theory, suggest that the transient response in the time domain can be converted into the spectrum in the frequency domain.

  20. Magnetic properties of core-shell (1/2-3/2) nanoparticle: Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Dakir, O.; El Kenz, A.; Benyoussef, A.

    2015-05-01

    In this work, a Monte Carlo simulation, based on standard Metropolis algorithm, has been applied to investigate magnetic properties of a ferrimagnetic nanoparticle, with a cubic shape and core-shell structure. The nanoparticle is constituted of spin-1/2 in the core surrounded by spin-3/2 in the shell. It has been shown that the exchange coupling plays an important role on the phase diagrams. Some interesting features have been observed for the temperature dependence of total magnetization curves of particle. In particular, the effects of the interface coupling and the shell coupling on both the compensation temperature and the magnetization profiles are investigated. In addition, the effect of the single ion anisotropy as well as the hysteresis loops behavior has also been discussed in detail.

  1. Formulation design facilitates magnetic nanoparticle delivery to diseased cells and tissues

    PubMed Central

    Singh, Dhirender; McMillan, JoEllyn M; Liu, Xin-Ming; Vishwasrao, Hemant M; Kabanov, Alexander V; Sokolsky-Papkov, Marina; Gendelman, Howard E

    2015-01-01

    Magnetic nanoparticles (MNPs) accumulate at disease sites with the aid of magnetic fields; biodegradable MNPs can be designed to facilitate drug delivery, influence disease diagnostics, facilitate tissue regeneration and permit protein purification. Because of their limited toxicity, MNPs are widely used in theranostics, simultaneously facilitating diagnostics and therapeutics. To realize therapeutic end points, iron oxide nanoparticle cores (5–30 nm) are encapsulated in a biocompatible polymer shell with drug cargos. Although limited, the toxic potential of MNPs parallels magnetite composition, along with shape, size and surface chemistry. Clearance is hastened by the reticuloendothelial system. To surmount translational barriers, the crystal structure, particle surface and magnetic properties of MNPs need to be optimized. With this in mind, we provide a comprehensive evaluation of advancements in MNP synthesis, functionalization and design, with an eye towards bench-to-bedside translation. PMID:24646020

  2. Magnetic, dielectric and sensing properties of manganese substituted copper ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Kumar, E. Ranjith; Jayaprakash, R.; Devi, G. Sarala; Reddy, P. Siva Prasada

    2014-04-01

    Manganese substituted copper ferrite nanoparticles were synthesized by an auto-combustion technique using metal nitrates and urea for gas sensor application. The products were characterized by XRD, SEM, EDX, TEM and VSM techniques. The effect of annealing temperature on the particle size, magnetic and dielectric properties of Mn-Cu ferrite nanoparticles was analyzed. The size of the particles are in the range of ~9-45 nm. The effect of annealing on the magnetic properties is discussed with the help of variation in saturation magnetization (Ms) and coercivity (Hc) by vibrating sample magnetometer (VSM). The dielectric loss and dielectric constant have been measured in the frequency range of 100 kHz-5 MHz. Furthermore, Conductance response of Mn-Cu ferrite nanomaterial was measured by exposing the material to reducing gas like liquefied petroleum gas (LPG).

  3. Mixed magnetic phases in Co3O4 nanoparticles synthesized by co-precipitation method

    NASA Astrophysics Data System (ADS)

    Rani, Stuti; Sharma, Yogesh; Varma, G. D.

    2014-04-01

    In the present manuscript, Co3O4 nanoparticles have been synthesized with the help of co-precipitation method and studied the structural, optical and magnetic properties. X ray diffraction analysis of the synthesized samples reveals the formation of single phase cubic spinel structure with the space group Fd-3m. FESEM and TEM results indicate the formation of nano-sized particles. The optical measurement reveals the two band gaps ˜2.77 and 1.67 eV in the sample. Magnetic measurement shows weak ferromagnetic interaction in Co3O4 along with usual paramagnetic nature at room temperature. However, at low temperatures the sample shows antiferromagnetic interaction. The correlation between the structural and observed magnetic and optical properties of Co3O4 nanoparticles will be described and discussed in this paper.

  4. Formulation design facilitates magnetic nanoparticle delivery to diseased cells and tissues.

    PubMed

    Singh, Dhirender; McMillan, JoEllyn M; Liu, Xin-Ming; Vishwasrao, Hemant M; Kabanov, Alexander V; Sokolsky-Papkov, Marina; Gendelman, Howard E

    2014-03-01

    Magnetic nanoparticles (MNPs) accumulate at disease sites with the aid of magnetic fields; biodegradable MNPs can be designed to facilitate drug delivery, influence disease diagnostics, facilitate tissue regeneration and permit protein purification. Because of their limited toxicity, MNPs are widely used in theranostics, simultaneously facilitating diagnostics and therapeutics. To realize therapeutic end points, iron oxide nanoparticle cores (5-30 nm) are encapsulated in a biocompatible polymer shell with drug cargos. Although limited, the toxic potential of MNPs parallels magnetite composition, along with shape, size and surface chemistry. Clearance is hastened by the reticuloendothelial system. To surmount translational barriers, the crystal structure, particle surface and magnetic properties of MNPs need to be optimized. With this in mind, we provide a comprehensive evaluation of advancements in MNP synthesis, functionalization and design, with an eye towards bench-to-bedside translation. PMID:24646020

  5. Effect of microstrain on the magnetic properties of BiFeO{sub 3} nanoparticles

    SciTech Connect

    Mocherla, Pavana S. V.; Sudakar, C., E-mail: csudakar@iitm.ac.in [Multifunctional Materials Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Karthik, C.; Ubic, R. [Department of Materials Science and Engineering, Boise State University, 1910 University Drive, Boise, Idaho 83725 (United States); Ramachandra Rao, M. S. [Department of Physics and Nano Functional Materials Technology Centre, Indian Institute of Technology Madras, Chennai 600036 (India)

    2014-09-29

    We report on size induced microstrain-dependent magnetic properties of BiFeO{sub 3} nanoparticles. The microstrain is found to be high (??>?0.3%) for smaller crystallite sizes (d?nanoparticles. Raman spectral studies suggest straightening of the Fe-O-Fe bond angle accompanied by a decrease in FeO{sub 6} octahedral rotation for d?magnetization shows a dip around 30?nm, half the size of spin cycloid length for BiFeO{sub 3}, due to a decrease in rhombohedral distortion with crystallite size. We also observe a similar trend in the T{sub N} with respect to size indicating that the microstrain plays a significant role in controlling the magnetic property of BiFeO{sub 3}.

  6. Efficient removal of pathogenic bacteria and viruses by multifunctional amine-modified magnetic nanoparticles.

    PubMed

    Zhan, Sihui; Yang, Yang; Shen, Zhiqiang; Shan, Junjun; Li, Yi; Yang, Shanshan; Zhu, Dandan

    2014-06-15

    A novel amine-functionalized magnetic Fe3O4-SiO2-NH2 nanoparticle was prepared by layer-by-layer method and used for rapid removal of both pathogenic bacteria and viruses from water. The nanoparticles were characterized by TEM, EDS, XRD, XPS, FT-IR, BET surface analysis, magnetic property tests and zeta-potential measurements, respectively, which demonstrated its well-defined core-shell structures and strong magnetic responsivity. Pathogenic bacteria and viruses are often needed to be removed conveniently because of a lot of co-existing conditions. The amine-modified nanoparticles we prepared were attractive for capturing a wide range of pathogens including not only bacteriophage f2 and virus (Poliovirus-1), but also various bacteria such as S. aureus, E. coli O157:H7, P. aeruginosa, Salmonella, and B. subtilis. Using as-prepared amine-functionalized MNPs as absorbent, the nonspecific removal efficiency of E. coli O157:H7 or virus was more than 97.39%, while it is only 29.8% with Fe3O4-SiO2 particles. From joint removal test of bacteria and virus, there are over 95.03% harmful E. coli O157:H7 that can be removed from mixed solution with polyclonal anti-E. coli O157:H7 antibody modified nanoparticles. Moreover, the synergy effective mechanism has also been suggested. PMID:24769848

  7. Site Determination and Magnetism of Mn Doping in Protein Encapsulated Iron Oxide Nanoparticles

    SciTech Connect

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

    2010-01-11

    Soft-X-ray absorption spectroscopy, soft-X-ray magnetic circular dichroism, and alternating current magnetic susceptibility were performed on 6.7 nm iron oxide nanoparticles doped with (5-33%) Mn grown inside the horse-spleen ferritin protein cages and compared to similarly protein encapsulated pure Fe-oxide and Mn-oxide nanoparticles to determine the site of the Mn dopant and to quantify the magnetic behavior with varying Mn concentration. The Mn dopant is shown to substitute preferentially as Mn{sup +2} and prefers the octahedral site in the defected spinel structure. The Mn multiplet structure for the nanoparticles is simpler than for the bulk standards, suggesting that the nanoparticle lattices are relaxed from the distortions present in the bulk. Addition of Mn is found to alter the host Fe-oxide lattice from a defected ferrimagnetic spinel structure similar to {gamma}-Fe{sub 2}O{sub 3} to an non-ferromagnetic spinel structure with a local Fe environment similar to Fe{sub 3}O{sub 4}.

  8. A highly sensitive magnetic biosensor for detection and quantification of anticancer drugs tagged to superparamagnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Wingo, J.; Devkota, J.; Mai, T. T. T.; Nguyen, X. P.; Mukherjee, P.; Srikanth, H.; Phan, M. H.; Vietnam Academy of Science and Technology Collaboration; University of South Florida Team

    2014-03-01

    A precise detection of low concentrations of biomolecules attached to magnetic nanoparticles in complex biological systems is a challenging task and requires biosensors with improved sensitivity. Here, we present a highly sensitive magnetic biosensor based on the magneto-reactance (MX) effect of a Co65Fe4Ni2Si15B14 amorphous ribbon with nanohole-patterned surface for detection and quantification of anticancer drugs (Curcumin) tagged to Fe3O4 nanoparticles. The detection and quantification of Curcumin were assessed by the change in MX of the ribbon subject to varying concentrations of the functionalized Fe3O4 nanoparticles. A high capacity of the MX-based biosensor in quantitative analysis of the nanoparticles was achieved in the range of 0 - 50 ng/ml, beyond which the detection sensitivity (?) remained unchanged. The ? of the biosensor reached an extremely high value of 30%, which is about 4-5 times higher than that of a magneto-impedance (MI) based biosensor. This biosensor is well suited for detection of low-concentration magnetic biomarkers in biological systems. This work was supported by was supported by the Florida Cluster for Advanced Smart Sensor Technologies, USAMRMC (Grant # W81XWH-07-1-0708), and the NSF-funded REU program at the USF.

  9. Magnetic Properties of Fe-alloy Catalyst Nanoparticles for Carbon Nanofiber Synthesis

    NASA Astrophysics Data System (ADS)

    Sorge, K. D.; Leventouri, Th.; Finkel, C.; Malkina, O.; Rack, P. D.; Melechko, A. V.; Fowlkes, J. D.; Klein, K. L.; Simpson, M. L.

    2006-03-01

    The magnetic properties of Fe-alloy nanoparticles, used as catalysts in vertically-aligned carbon nanofiber (VACNF) growth, has been investigated. First, Fe and Co or Ni were co-sputtered onto Si substrates in order to make a catalyst alloy film. These substrates were then placed in a plasma-enhanced CVD chamber with a substrate temperature of 700^oC and a flowing mixture of acetylene (C2H2) and ammonia (NH3) gas. During the PECVD, the catalyst film breaks into nanoparticles of 50--200 nm and VACNFs are grown. EDX shows that the catalyst nanoparticles nominally have the deposited alloy ratio. In addition, the nanoparticles are still magnetic and have a non-negligible remanence and hysteresis. Their magnetic properties are investigated by SQUID magnetometry in applied field of |H| <=50 kOe and temperatures of 5--400 K. In addition, AC susceptibility studies give energy loss characteristics of the co-synthesized VACNF system.

  10. Construction of orthogonal synchronized bi-directional field to enhance heating efficiency of magnetic nanoparticles.

    PubMed

    Chen, Shih-Wei; Lai, Jr-Jie; Chiang, Chen-Li; Chen, Cheng-Lung

    2012-06-01

    Magnetic hyperthermia using magnetic nanoparticles (MNPs) has attracted considerable attention as one of the promising tumor therapy. The study has been developed under single magnetic field. Recently, we found that the immobile MNP may generate more heat under two synchronous ac magnetic fields than traditional single and circular polarized fields based on model simulation result. According to this finding we constructed an orthogonal synchronized bi-directional field (OSB field). The system contained two LC resonant inverters (L: inductor, C: capacitor) and both vertical and transverse ac magnetic fields were generated by two Helmholtz coils. To reduce the interference, the axis directional of two coils were arranged orthogonally. The experiments showed that the heating ability of aggregated MNPs is greatly enhanced under this newly designed OSB field without increasing the strength of magnetic field. The OSB field system provides a promising way for future clinical hyperthermia. PMID:22755645

  11. Structural, electrical, magnetic and multiferroism in Dy-doped BiFeO3 nanoparticles

    NASA Astrophysics Data System (ADS)

    Lotey, Gurmeet Singh; Verma, N. K.

    2013-06-01

    Nanostructural, multifunctional, multiferroic materials possessing strong magnetoelectric coupling, open exciting multitudinous ways for designing future spintronic and data storage device applications. Pure and 15% Dy-doped BiFeO3 multiferroic nanoparticles (NPs) with size 24 and 20 nm respectively have been synthesized by sol-gel method. The effect of Dy-doping and size of synthesized nanoparticles on structural, electrical, magnetic and magnetodielectric properties have been investigated. The magnetoelectric coupling (ME) in synthesized NPs have been estimated by measuring magnetodielectric. The possible origin of enhancement in above said properties have been explained on the basis of dopant, phase purity, structural transformation and the small size synthesized NPs.

  12. Magnetic nanoparticles coated with carboxymethylated polysaccharide shells—Interaction with human cells

    NASA Astrophysics Data System (ADS)

    Wotschadlo, Jana; Liebert, Tim; Heinze, Thomas; Wagner, Kerstin; Schnabelrauch, Matthias; Dutz, Silvio; Müller, Robert; Steiniger, Frank; Schwalbe, Manuela; Kroll, Torsten C.; Höffken, Klaus; Buske, Norbert; Clement, Joachim H.

    2009-05-01

    The interaction of magnetic core shell nanoparticles with living cells depends on the structure of the shell. In this paper we demonstrate a strong difference in the cell-nanoparticle interaction depending on the backbone of carboxymethylated polysaccharides used as shell material. Carboxymethyl cellulose with its ?-1?4 linked structure and the carboxymethylated pullulan [?-1?6 linked maltotriose with ?-1?4 linkages] show a constant interaction rate with both, tumor cells and leukocytes. In contrast, carboxymethyl dextran with a ?-1?6 linked backbone exhibits a rapid interaction kinetic with tumor cells that is reduced with leukocytes as target.

  13. High-magnetic-moment core-shell-type FeCo-Au\\/Ag nanoparticles

    Microsoft Academic Search

    Jianmin Bai; Jian-Ping Wang

    2005-01-01

    We developed a physical technique combining an on-line sputtering\\/evaporation process with an integrated nanocluster deposition process to prepare core-shell-type nanoparticles. High-magnetic-moment (Fe60Co40)coreAushell and (Fe60Co40)coreAgshell superparamagnetic nanoparticles with controllable particle size of 10-20 nm and Au\\/Ag shell thickness of 1-3 nm were prepared by using this method. Au shell is not only functional for the potential biocompatibility but also the key

  14. Magnetic nanoparticle-based approaches to locally target therapy and enhance tissue regeneration in vivo

    PubMed Central

    Sensenig, Richard; Sapir, Yulia; MacDonald, Cristin; Cohen, Smadar; Polyak, Boris

    2013-01-01

    Magnetic-based systems utilizing superparamagnetic nanoparticles and a magnetic field gradient to exert a force on these particles have been used in a wide range of biomedical applications. This review is focused on drug targeting applications that require penetration of a cellular barrier as well as strategies to improve the efficacy of targeting in these biomedical applications. Another focus of this review is regenerative applications utilizing tissue engineered scaffolds prepared with the aid of magnetic particles, the use of remote actuation for release of bioactive molecules and magneto–mechanical cell stimulation, cell seeding and cell patterning. PMID:22994959

  15. One-stop Genomic DNA Extraction by Salicylic Acid Coated Magnetic Nanoparticles

    PubMed Central

    Zhou, Zhongwu; Kadam, Ulhas; Irudayaraj, Joseph

    2014-01-01

    Salicylic acid coated magnetic nanoparticles were prepared via a modified, one-step synthesis and used for a one-stop extraction of genomic DNA from mammalian cells. The synthesized magnetic particles were used for magnetic separation of cells from the media by non-specific binding of the particles, as well as extraction of genomic DNA from the lysate. The quantity and quality were confirmed by agarose gel electrophoresis and polymerase chain reaction. The entire process of extraction and isolation can be completed within 30 min. Compared to traditional methods based on centrifugation and filtration, the established method is fast, simple, reliable, and environmentally-friendly. PMID:23911528

  16. Application of magnetic nanoparticles in full-automated chemiluminescent enzyme immunoassay

    NASA Astrophysics Data System (ADS)

    Xie, Xiaomao; Ohnishi, Noriyuki; Takahashi, Yuki; Kondo, Akihiko

    2009-05-01

    The magnetic nanoparticles (MNPs) Therma-Max™ were used as a carrier to develop an automated sandwich chemiluminescent enzyme immunoassay (CLEIA) to detect thyroid-stimulating hormone (TSH) in a sensitive and specific way. The Therma-Max™ particles allow for automation because, unlike magnetic microspheres, they are completely dispersed in aqueous solution and allow for accurate automatic handling. Signal intensities detected with MNPs were 8-fold higher than those found with conventional micron-sized magnetic particles. A reproducibility study suggests that these particles allow for a stable detection method, as the coefficient of variation (CV) is less than 6% ( n=10).

  17. Stability and magnetically induced heating behavior of lipid-coated Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Allam, Ayat A.; Sadat, Md Ehsan; Potter, Sarah J.; Mast, David B.; Mohamed, Dina F.; Habib, Fawzia S.; Pauletti, Giovanni M.

    2013-10-01

    Magnetic nanoparticles that are currently explored for various biomedical applications exhibit a high propensity to minimize total surface energy through aggregation. This study introduces a unique, thermoresponsive nanocomposite design demonstrating substantial colloidal stability of superparamagnetic Fe3O4 nanoparticles (SPIONs) due to a surface-immobilized lipid layer. Lipid coating was accomplished in different buffer systems, pH 7.4, using an equimolar mixture of 1,2-dipalmitoyl- sn-glycero-3-phosphocholine (DPPC) and l-?-dipalmitoylphosphatidyl glycerol (DPPG). Particle size and zeta potential were measured by dynamic laser light scattering. Heating behavior within an alternating magnetic field was compared between the commercial MFG-1000 magnetic field generator at 7 mT (1 MHz) and an experimental, laboratory-made magnetic hyperthermia system at 16.6 mT (13.7 MHz). The results revealed that product quality of lipid-coated SPIONs was significantly dependent on the colloidal stability of uncoated SPIONs during the coating process. Greatest stability was achieved at 0.02 mg/mL in citrate buffer (mean diameter = 80.0 ± 1.7 nm; zeta potential = -47.1 ± 2.6 mV). Surface immobilization of an equimolar DPPC/DPPG layer effectively reduced the impact of buffer components on particle aggregation. Most stable suspensions of lipid-coated nanoparticles were obtained at 0.02 mg/mL in citrate buffer (mean diameter = 179.3 ± 13.9 nm; zeta potential = -19.1 ± 2.3 mV). The configuration of the magnetic field generator significantly affected the heating properties of fabricated SPIONs. Heating rates of uncoated nanoparticles were substantially dependent on buffer composition but less influenced by particle concentration. In contrast, thermal behavior of lipid-coated nanoparticles within an alternating magnetic field was less influenced by suspension vehicle but dramatically more sensitive to particle concentration. These results underline the advantages of lipid-coated SPIONs on colloidal stability without compromising magnetically induced hyperthermia properties. Since phospholipids are biocompatible, these unique lipid-coated Fe3O4 nanoparticles offer exciting opportunities as thermoresponsive drug delivery carriers for targeted, stimulus-induced therapeutic interventions.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

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

    NASA Astrophysics Data System (ADS)

    Sun, Conroy Ghin Chee

    Magnetic nanoparticles (MNPs) possess unique magnetic properties and the ability to function at the cellular and molecular level of biological interactions making them an attractive platform to serve as contrast agents for magnetic resonance imaging (MRI) and as carriers for drug delivery. Recent advances in nanotechnology have improved the ability to engineer the features and properties of MNPs allowing them to be tailored specifically for these biomedical applications. MNPs composed of metallic, oxide, and nanoalloy cores and a variety of protective coatings are being investigated for applications in the detection, diagnosis, and treatment of malignant tumors, cardiovascular disease, and neurological disease. To better address specific clinical needs, MNPs with higher magnetic moments, non-fouling surfaces, and increased functionalities are now being developed. The goal of this interdisciplinary research is to develop novel superparamagnetic nanoprobes for non-invasive cancer diagnosis and treatment. This strategy utilizes iron oxide nanoparticles coated with various biocompatible polymers, such as poly(ethylene glycol) (PEG) and chitosan, to serve as both a contrast agent for MRI and a carrier for drug delivery. In this project, we have conjugated various targeting agents, such as folic acid (FA) and chlorotoxin (CTX), to these iron oxide nanoparticles to improve their tumor specific accumulation. The folate receptor is known to be overexpressed on the surfaces of many human tumor cells, including ovarian, lung, breast, endometrial, renal, and colon cancers, while CTX binds with high affinity to gliomas, medulloblastomas, and other tumors of the neuroectodermal origin. To evaluate its effectiveness as a targeted drug carrier, methotrexate (MTX), a convention chemotherapeutic agent, was conjugated to iron oxide nanoparticles in combination with CTX. Specific tumor cell targeting of our nanoparticle system has been demonstrated through increased contrast enhancement both in vitro and in vivo in MRI experiments. The successful application of such smart molecular imaging probes will have a significant clinical impact on improved diagnosis and treatment of malignant tumors.

  20. Bioconjugation of poly(poly(ethylene glycol) methacrylate)-coated iron oxide magnetic nanoparticles for magnetic capture of target proteins

    Microsoft Academic Search

    Sung Min Kang; Insung S. Choi; Kyung-Bok Lee; Yongseong Kim

    2009-01-01

    Chemical modification of magnetic nanoparticles (MNPs) with functional polymers has recently gained a great deal of attention\\u000a because of the potential application of MNPs toin vivo andin vitro biotechnology. The potential use of MNPs as capturing agents and sensitive biosensors has been intensively investigated because\\u000a MNPs exhibit good separation-capability and binding-specificity for biomolecules after suitable surface functionalization\\u000a processes. In this