Science.gov

Sample records for magnetic nanoparticles attached

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  2. Electrocatalytic features of a heme protein attached to polymer-functionalized magnetic nanoparticles.

    PubMed

    Krishnan, Sadagopan; Walgama, Charuksha

    2013-12-03

    Direct electron-transfer and electrocatalytic kinetics of covalently attached myoglobin (MB) films on magnetic nanoparticles (MB-MNP(covalent)), in comparison to the corresponding physisorbed films and individual components, are reported for the first time. MB-MNP(covalent) ("-" denotes a covalent linkage) was adsorbed onto a cationic poly(ethyleneimine) layer (PEI) coated high-purity graphite (HPG) electrode. Similarly, films of myoglobin physisorbed on magnetic nanoparticles (MB/MNP(adsorbed), "/" denotes a noncovalent nature), only MB, or only MNP were constructed on HPG/PEI electrodes for comparison. The observed electron-transfer rate constants (k(s), s(-1)) were in the following order: MB-MNP(covalent) (69 ± 6 s(-1)), MB/MNP(adsorbed) (37 ± 2 s(-1)), only MB (27 ± 2 s(-1)), and only MNP (16 ± 3 s(-1)). The electrocatalytic properties of these films were investigated with the aid of tert-butylhydroperoxide as a model reactant, and its reduction kinetics were examined. We observed the following order of catalytic current density: MB-MNP(covalent) > MB/MNP(adsorbed) > only MNP > only MB, in agreement with the electron-transfer (ET) rates of MB-MNP(covalent) and MB/MNP(adsorbed) films. The crucial function of MNP in favorably altering the direct ET and electrocatalytic properties of both covalently bound MB and physisorbed MB molecules are discussed. In addition, the occurrence of a highly enhanced electron-hopping mechanism in the designed covalent MB-MNP(covalent) films over the corresponding physisorbed MB/MNP(adsorbed) film is proposed. The enhanced electron-transfer rates and catalytic current density suggest the advantages of using metalloenzymes covalently attached to polymer-functionalized magnetic nanoparticles for the development of modern highly efficient miniature biosensors and bioreactors.

  3. Surface functionalization of silica-coated magnetic nanoparticles for covalent attachment of cholesterol oxidase

    NASA Astrophysics Data System (ADS)

    Šulek, Franja; Drofenik, Miha; Habulin, Maja; Knez, Željko

    2010-01-01

    A systematic approach towards the fabrication of highly functionalized silica shell magnetic nanoparticles, presently used for enzyme immobilization, is herein fully presented. The synthesis of bare maghemite (γ-Fe 2O 3) nanoparticles was accomplished by thermal co-precipitation of iron ions in ammonia alkaline solution at harsh reaction conditions, respectively. Primary surface engineering of maghemite nanoparticles was successfully performed by the proper deposition of silica onto nanoparticles surface under strictly regulated reaction conditions. Next, the secondary surface functionalization of the particles was achieved by coating the particles with organosilane followed by glutaraldehyde activation in order to enhance protein immobilization. Covalent immobilization of cholesterol oxidase was attempted afterwards. The structural and magnetic properties of magnetic silica nanocomposites were characterized by TEM and vibrating sample magnetometer (VSM) instruments. X-ray diffraction measurements confirmed the spinel structure and average size of uncoated maghemite nanoparticles to be around 20 nm in diameter. SEM-EDS spectra indicated a strong signal for Si, implying the coating procedure of silica onto the particles surface to be successfully accomplished. Fourier transform infrared (FT-IR) spectra analysis confirmed the binding of amino silane molecules onto the surface of the maghemite nanoparticles mediated Si-O-Si chemical bonds. Compared to the free enzyme, the covalently bound cholesterol oxidase retained 50% of its activity. Binding of enzyme onto chemically modified magnetic nanoparticles via glutaraldehyde activation is a promising method for developing biosensing components in biomedicine.

  4. Platinum Attachments on Iron Oxide Nanoparticle Surfaces

    SciTech Connect

    Palchoudhury, Soubantika; Xu, Yaolin; An, Wei; Turner, C. H.; Bao, Yuping

    2010-04-30

    Platinum nanoparticles supported on metal oxide surfaces have shown great potential as heterogeneous catalysts to accelerate electrochemical processes, such as the oxygen reduction reaction in fuel cells. Recently, the use of magnetic supports has become a promising research topic for easy separation and recovery of catalysts using magnets, such as Pt nanoparticles supported on iron oxide nanoparticles. The attachment of Pt on iron oxide nanoparticles is limited by the wetting ability of the Pt (metal) on ceramic surfaces. A study of Pt nanoparticle attachment on iron oxide nanoparticle surfaces in an organic solvent is reported, which addresses the factors that promote or inhibit such attachment. It was discovered that the Pt attachment strongly depends on the capping molecules of the iron oxide seeds and the reaction temperature. For example, the attachment of Pt nanoparticles on oleic acid coated iron oxide nanoparticles was very challenging, because of the strong binding between the carboxylic groups and iron oxide surfaces. In contrast, when nanoparticles are coated with oleic acid/tri-n-octylphosphine oxide or oleic acid/oleylamine, a significant increase in Pt attachment was observed. Electronic structure calculations were then applied to estimate the binding energies between the capping molecules and iron ions, and the modeling results strongly support the experimental observations.

  5. Oriented Attachment of Recombinant Proteins to Agarose-Coated Magnetic Nanoparticles by Means of a β-Trefoil Lectin Domain.

    PubMed

    Acebrón, Iván; Ruiz-Estrada, Amalia G; Luengo, Yurena; Morales, María Del Puerto; Guisán, José Manuel; Mancheño, José Miguel

    2016-11-16

    Design of generic methods aimed at the oriented attachment of proteins at the interfacial environment of magnetic nanoparticles currently represents an active field of research. With this in mind, we have prepared and characterized agarose-coated maghemite nanoparticles to set up a platform for the attachment of recombinant proteins fused to the β-trefoil lectin domain LSL150, a small protein that combines fusion tag properties with agarose-binding capacity. Analysis of the agarose-coated nanoparticles by dynamic light scattering, Fourier transform infrared spectroscopy, and thermogravimetric studies shows that decoupling particle formation from agarose coating provides better results in terms of coating efficiency and particle size distribution. LSL150 interacts with these agarose-coated nanoparticles exclusively through the recognition of the sugars of the polymer, forming highly stable complexes, which in turn can be dissociated ad hoc with the competing sugar lactose. Characterization of the complexes formed with the fusion proteins LSL-EGFP (LSL-tagged enhanced green fluorescent protein from Aquorea victoria) and LSL-BTL2 (LSL-tagged lipase from Geobacillus thermocatenolatus) provided evidence supporting a topologically oriented binding of these molecules to the interface of the agarose-coated nanoparticles. This is consistent with the marked polarity of the β-trefoil structure where the sugar-binding sites and the N- and C-terminus ends are at opposed sides. In summary, LSL150 displays topological and functional features expected from a generic molecular adaptor for the oriented attachment of proteins at the interface of agarose-coated nanoparticles.

  6. Magnetically attached sputter targets

    DOEpatents

    Makowiecki, D.M.; McKernan, M.A.

    1994-02-15

    An improved method and assembly for attaching sputtering targets to cathode assemblies of sputtering systems which includes a magnetically permeable material is described. The magnetically permeable material is imbedded in a target base that is brazed, welded, or soldered to the sputter target, or is mechanically retained in the target material. Target attachment to the cathode is achieved by virtue of the permanent magnets and/or the pole pieces in the cathode assembly that create magnetic flux lines adjacent to the backing plate, which strongly attract the magnetically permeable material in the target assembly. 11 figures.

  7. Magnetically attached sputter targets

    DOEpatents

    Makowiecki, Daniel M.; McKernan, Mark A.

    1994-01-01

    An improved method and assembly for attaching sputtering targets to cathode assemblies of sputtering systems which includes a magnetically permeable material. The magnetically permeable material is imbedded in a target base that is brazed, welded, or soldered to the sputter target, or is mechanically retained in the target material. Target attachment to the cathode is achieved by virtue of the permanent magnets and/or the pole pieces in the cathode assembly that create magnetic flux lines adjacent to the backing plate, which strongly attract the magnetically permeable material in the target assembly.

  8. Overdentures with magnetic attachments.

    PubMed

    Gillings, B R; Samant, A

    1990-10-01

    Magnets were used only occasionally for dental purposes several decades ago. Since the advent of rare earth magnet alloys, however, intraoral magnets are shaping the course of aesthetics and retention for both complete and removable partial overdentures. Their benefits include simplicity, low cost, self-adjustment, inherent stress breaking, automatic reseating after denture displacement, comparative freedom of lateral denture movement, a low potential for trauma to the retained roots, and elimination of the need for adjustment in service. The clinical procedures involved in their application do not require any special skills, and the options offered by the various manufacturers give the dentist a wide variety of choices in selecting an appropriate treatment plan. Clinical experience has shown that magnetic retention offers an economical alternative for teeth that would otherwise require expensive or extensive restorative treatment, and can be used as an effective and often superior replacement for failed bridgework. Finally, it is clear that overdenture treatment per se is a valuable option for the dentist, and the use of magnets expands this option to the retention of tooth roots that might otherwise be scheduled for extraction. The natural tooth root, even if periodontally involved, can serve as a useful aid in denture support and retention, and should be regarded as at least as good as, and in most cases superior to, an implant. It is also much less expensive.

  9. Magnetic nanoparticles for "smart liposomes".

    PubMed

    Nakayama, Yoshitaka; Mustapić, Mislav; Ebrahimian, Haleh; Wagner, Pawel; Kim, Jung Ho; Hossain, Md Shahriar Al; Horvat, Joseph; Martinac, Boris

    2015-12-01

    Liposomal drug delivery systems (LDDSs) are promising tools used for the treatment of diseases where highly toxic pharmacological agents are administered. Currently, destabilising LDDSs by a specific stimulus at a target site remains a major challenge. The bacterial mechanosensitive channel of large conductance (MscL) presents an excellent candidate biomolecule that could be employed as a remotely controlled pore-forming nanovalve for triggered drug release from LDDSs. In this study, we developed superparamagnetic nanoparticles for activation of the MscL nanovalves by magnetic field. Synthesised CoFe2O4 nanoparticles with the radius less than 10 nm were labelled by SH groups for attachment to MscL. Activation of MscL by magnetic field with the nanoparticles attached was examined by the patch clamp technique showing that the number of activated channels under ramp pressure increased upon application of the magnetic field. In addition, we have not observed any cytotoxicity of the nanoparticles in human cultured cells. Our study suggests the possibility of using magnetic nanoparticles as a specific trigger for activation of MscL nanovalves for drug release in LDDSs.

  10. Magnetically Attached Multifunction Maintenance Rover

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph; Joffe, Benjamin

    2005-01-01

    A versatile mobile telerobot, denoted the magnetically attached multifunction maintenance rover (MAGMER), has been proposed for use in the inspection and maintenance of the surfaces of ships, tanks containing petrochemicals, and other large ferromagnetic structures. As its name suggests, this robot would utilize magnetic attraction to adhere to a structure. As it moved along the surface of the structure, the MAGMER would perform tasks that could include close-up visual inspection by use of video cameras, various sensors, and/or removal of paint by water-jet blasting, laser heating, or induction heating. The water-jet nozzles would be mounted coaxially within compressed-air-powered venturi nozzles that would collect the paint debris dislodged by the jets. The MAGMER would be deployed, powered, and controlled from a truck, to which it would be connected by hoses for water, compressed air, and collection of debris and by cables for electric power and communication (see Figure 1). The operation of the MAGMER on a typical large structure would necessitate the use of long cables and hoses, which can be heavy. To reduce the load of the hoses and cables on the MAGMER and thereby ensure its ability to adhere to vertical and overhanging surfaces, the hoses and cables would be paid out through telescopic booms that would be parts of a MAGMER support system. The MAGMER would move by use of four motorized, steerable wheels, each of which would be mounted in an assembly that would include permanent magnets and four pole pieces (see Figure 2). The wheels would protrude from between the pole pieces by only about 3 mm, so that the gap between the pole pieces and the ferromagnetic surface would be just large enough to permit motion along the surface but not so large as to reduce the magnetic attraction excessively. In addition to the wheel assemblies, the MAGMER would include magnetic adherence enhancement fixtures, which would comprise arrays of permanent magnets and pole pieces

  11. Metallic magnetic nanoparticles.

    PubMed

    Hernando, A; Crespo, P; García, M A

    2005-12-22

    In this paper, we reviewed some relevant aspects of the magnetic properties of metallic nanoparticles with small size (below 4 nm), covering the size effects in nanoparticles of magnetic materials, as well as the appearance of magnetism at the nanoscale in materials that are nonferromagnetic in bulk. These results are distributed along the text that has been organized around three important items: fundamental magnetic properties, different fabrication procedures, and characterization techniques. A general introduction and some experimental results recently obtained in Pd and Au nanoparticles have also been included. Finally, the more promising applications of magnetic nanoparticles in biomedicine are indicated. Special care was taken to complete the literature available on the subject.

  12. 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

  13. Structural characterization of copolymer embedded magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Nedelcu, G. G.; Nastro, A.; Filippelli, L.; Cazacu, M.; Iacob, M.; Rossi, C. Oliviero; Popa, A.; Toloman, D.; Dobromir, M.; Iacomi, F.

    2015-10-01

    Small magnetic nanoparticles (Fe3O4) were synthesized by co-precipitation and coated by emulsion polymerization with poly(methyl methacrylate-co-acrylic acid) (PMMA-co-AAc) to create surface functional groups that can attach drug molecules and other biomolecules. The coated and uncoated magnetite nanoparticles were stored for two years in normal closed ships and than characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, vibrating sample magnetometry, and electron paramagnetic resonance spectroscopy. The solid phase transformation of magnetite to maghemite, as well as an increase in particle size were evidenced for the uncoated nanoparticles. The coated nanoparticles preserved their magnetite structure and magnetic properties. The influences of monomers and surfactant layers on interactions between the magnetic nanoparticles evidenced that the thickness of the polymer has a significant effect on magnetic properties.

  14. Biotemplated magnetic nanoparticle arrays.

    PubMed

    Galloway, Johanna M; Bramble, Jonathan P; Rawlings, Andrea E; Burnell, Gavin; Evans, Stephen D; Staniland, Sarah S

    2012-01-23

    Immobilized biomineralizing protein Mms6 templates the formation of uniform magnetite nanoparticles in situ when selectively patterned onto a surface. Magnetic force microscopy shows that the stable magnetite particles maintain their magnetic orientation at room temperature, and may be exchange coupled. This precision-mixed biomimetic/soft-lithography methodology offers great potential for the future of nanodevice fabrication.

  15. Magnetoacoustic Sensing of Magnetic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kellnberger, Stephan; Rosenthal, Amir; Myklatun, Ahne; Westmeyer, Gil G.; Sergiadis, George; Ntziachristos, Vasilis

    2016-03-01

    The interaction of magnetic nanoparticles and electromagnetic fields can be determined through electrical signal induction in coils due to magnetization. However, the direct measurement of instant electromagnetic energy absorption by magnetic nanoparticles, as it relates to particle characterization or magnetic hyperthermia studies, has not been possible so far. We introduce the theory of magnetoacoustics, predicting the existence of second harmonic pressure waves from magnetic nanoparticles due to energy absorption from continuously modulated alternating magnetic fields. We then describe the first magnetoacoustic system reported, based on a fiber-interferometer pressure detector, necessary for avoiding electric interference. The magnetoacoustic system confirmed the existence of previously unobserved second harmonic magnetoacoustic responses from solids, magnetic nanoparticles, and nanoparticle-loaded cells, exposed to continuous wave magnetic fields at different frequencies. We discuss how magnetoacoustic signals can be employed as a nanoparticle or magnetic field sensor for biomedical and environmental applications.

  16. Magnetoacoustic Sensing of Magnetic Nanoparticles.

    PubMed

    Kellnberger, Stephan; Rosenthal, Amir; Myklatun, Ahne; Westmeyer, Gil G; Sergiadis, George; Ntziachristos, Vasilis

    2016-03-11

    The interaction of magnetic nanoparticles and electromagnetic fields can be determined through electrical signal induction in coils due to magnetization. However, the direct measurement of instant electromagnetic energy absorption by magnetic nanoparticles, as it relates to particle characterization or magnetic hyperthermia studies, has not been possible so far. We introduce the theory of magnetoacoustics, predicting the existence of second harmonic pressure waves from magnetic nanoparticles due to energy absorption from continuously modulated alternating magnetic fields. We then describe the first magnetoacoustic system reported, based on a fiber-interferometer pressure detector, necessary for avoiding electric interference. The magnetoacoustic system confirmed the existence of previously unobserved second harmonic magnetoacoustic responses from solids, magnetic nanoparticles, and nanoparticle-loaded cells, exposed to continuous wave magnetic fields at different frequencies. We discuss how magnetoacoustic signals can be employed as a nanoparticle or magnetic field sensor for biomedical and environmental applications.

  17. In vivo MRI of single-wall carbon nanohorns through magnetite nanoparticle attachment

    NASA Astrophysics Data System (ADS)

    Miyawaki, Jin; Yudasaka, Masako; Imai, Hideto; Yorimitsu, Hideki; Isobe, Hiroyuki; Nakamura, Eiichi; Iijima, Sumio

    2006-03-01

    Superparamagnetic magnetite (SPM) is used as a contrast agent in magnetic resonance imaging (MRI). Thus, the SPM-attachment to carbon nanotubes (CNTs) will enable to visualize motional behaviors of CNTs in the living body through MRI. We found that the strong attachment of the SPM nanoparticles (ca. 6 nm size) to one type of CNTs, single-wall carbon nanohorns (SWNHs), could be achieved through a deposition of iron acetate clusters on SWNHs in ethanol at room temperature, followed by heat-treatment in Ar. In vivo MRI visualized that the SWNHs attached with the SPM nanoparticles accumulated in several organs of mice when injected into mice via tail veins. This simple method for the SPM-attaching on CNTs would facilitate the toxicity assessment of CNTs and the applications of CNTs in bioscience and biotechnology.

  18. Magnetic nanoparticles for theragnostics

    PubMed Central

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

    2009-01-01

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

  19. Multifunctional magnetic nanoparticles: design, synthesis, and biomedical applications.

    PubMed

    Gao, Jinhao; Gu, Hongwei; Xu, Bing

    2009-08-18

    The combination of nanotechnology and molecular biology has developed into an emerging research area: nanobiotechnology. Magnetic nanoparticles are well-established nanomaterials that offer controlled size, ability to be manipulated externally, and enhancement of contrast in magnetic resonance imaging (MRI). As a result, these nanoparticles could have many applications in biology and medicine, including protein purification, drug delivery, and medical imaging. Because of the potential benefits of multimodal functionality in biomedical applications, researchers would like to design and fabricate multifunctional magnetic nanoparticles. Currently, there are two strategies to fabricate magnetic nanoparticle-based multifunctional nanostructures. The first, molecular functionalization, involves attaching antibodies, proteins, and dyes to the magnetic nanoparticles. The other method integrates the magnetic nanoparticles with other functional nanocomponents, such as quantum dots (QDs) or metallic nanoparticles. Because they can exhibit several features synergistically and deliver more than one function simultaneously, such multifunctional magnetic nanoparticles could have unique advantages in biomedical applications. In this Account, we review examples of the design and biomedical application of multifunctional magnetic nanoparticles. After their conjugation with proper ligands, antibodies, or proteins, the biofunctional magnetic nanoparticles exhibit highly selective binding. These results indicate that such nanoparticles could be applied to biological medical problems such as protein purification, bacterial detection, and toxin decorporation. The hybrid nanostructures, which combine magnetic nanoparticles with other nanocomponents, exhibit paramagnetism alongside features such as fluorescence or enhanced optical contrast. Such structures could provide a platform for enhanced medical imaging and controlled drug delivery. We expect that the combination of unique structural

  20. 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.

  1. 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

  2. Magnetic Nanoparticles for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Jing, Ying

    Nanotechnology is revolutionizing human's life. Synthesis and application of magnetic nanoparticles is a fast burgeoning field which has potential to bring significant advance in many fields, for example diagnosis and treatment in biomedical area. Novel nanoparticles to function efficiently and intelligently are in desire to improve the current technology. We used a magnetron-sputtering-based nanocluster deposition technique to synthesize magnetic nanoparticles in gas phase, and specifically engineered nanoparticles for different applications. Alternating magnetic field heating is emerging as a technique to assist cancer treatment or drug delivery. We proposed high-magnetic-moment Fe3Si particles with relatively large magnetic anisotropy energy should in principle provide superior performance. Such nanoparticles were experimentally synthesized and characterized. Their promising magnetic properties can contribute to heating performance under suitable alternating magnetic field conditions. When thermal energy is used for medical treatment, it is ideal to work in a designed temperature range. Biocompatible and "smart" magnetic nanoparticles with temperature self-regulation were designed from both materials science and biomedicine aspects. We chose Fe-Si material system to demonstrate the concept. Temperature dependent physical property was adjusted by tuning of exchange coupling between Fe atoms through incorporation of various amount of Si. The magnetic moment can still be kept in a promising range. The two elements are both biocompatible, which is favored by in-vivo medical applications. A combination of "smart" magnetic particles and thermo-sensitive polymer were demonstrated to potentially function as a platform for drug delivery. Highly sensitive diagnosis for point-of-care is in desire nowadays. We developed composition- and phase-controlled Fe-Co nanoparticles for bio-molecule detection. It has been demonstrated that Fe70Co30 nanoparticles and giant

  3. Controlling transport and chemical functionality of magnetic nanoparticles.

    PubMed

    Latham, Andrew H; Williams, Mary Elizabeth

    2008-03-01

    A wide range of metal, magnetic, semiconductor, and polymer nanoparticles with tunable sizes and properties can be synthesized by wet-chemical techniques. Magnetic nanoparticles are particularly attractive because their inherent superparamagnetic properties make them desirable for medical imaging, magnetic field assisted transport, and separations and analyses. With such applications on the horizon, synthetic routes for quickly and reliably rendering magnetic nanoparticle surfaces chemically functional have become an increasingly important focus. This Account describes common synthetic routes for making and functionalizing magnetic nanoparticles and discusses initial applications in magnetic field induced separations. The most widely studied magnetic nanoparticles are iron oxide (Fe2O3 and Fe3O4), cobalt ferrite (CoFe 2O4), iron platinum (FePt), and manganese ferrite (MnFe 2O4), although others have been investigated. Magnetic nanoparticles are typically prepared under either high-temperature organic phase or aqueous conditions, producing particles with surfaces that are stabilized by attached surfactants or associated ions. Although it requires more specialized glassware, high-temperature routes are generally preferred when a high degree of stability and low particle size dispersity is desired. Particles can be further modified with a secondary metal or polymer to create core-shell structures. The outer shells function as protective layers for the inner metal cores and alter the surface chemistry to enable postsynthetic modification of the surfactant chemistry. Efforts by our group as well as others have centered on pathways to yield nanoparticles with surfaces that are both easily functionalized and tunable in terms of the number and variety of attached species. Ligand place-exchange reactions have been shown quite successful for exchanging silanes, acids, thiols, and dopamine ligands onto the surfaces of some magnetic particles. Poly(ethylene oxide

  4. Magnetic nanoparticles as targeted delivery systems in oncology

    PubMed Central

    Prijic, Sara; Sersa, Gregor

    2011-01-01

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

  5. 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 μg 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.

  6. 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

  7. Magnetic nanoparticles in medical nanorobotics

    NASA Astrophysics Data System (ADS)

    Martel, Sylvain

    2015-02-01

    Medical nanorobotics is a field of robotics that exploits the physics at the nanoscale to implement new functionalities in untethered robotic agents aimed for ultimate operations in constrained physiological environments of the human body. The implementation of such new functionalities is achieved by embedding specific nano-components in such robotic agents. Because magnetism has been and still widely used in medical nanorobotics, magnetic nanoparticles (MNP) in particular have shown to be well suited for this purpose. To date, although such magnetic nanoparticles play a critical role in medical nanorobotics, no literature has addressed specifically the use of MNP in medical nanorobotic agents. As such, this paper presents a short introductory tutorial and review of the use of magnetic nanoparticles in the field of medical nanorobotics with some of the related main functionalities that can be embedded in nanorobotic agents.

  8. Magnetic properties of carbon nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

    Magnetization M (T, B) of powder and glassy samples containing carbon nanoparticles is investigated in the interval of temperatures T between ~ 3 - 300 K and magnetic fields B up to 5 T. Low-field magnetization, M (T), exhibits a strong magnetic irreversibility, which is suppressed above the field of ~ 1 T. The dependence of M (B) saturates at high temperatures above B ~ 2 T, magnetic hysteresis is observed already at 300 K. The values of the saturation magnetization, the coercivity field and the maximum blocking temperature are obtained. Analysis of the experimental data gives evidence for concentration of the magnetization close to the surface of the particles, which is consistent with the origin of magnetism in nanocarbon presumably due to intrinsic disorder and surface defects.

  9. Technique to optimize magnetic response of gelatin coated magnetic nanoparticles.

    PubMed

    Parikh, Nidhi; Parekh, Kinnari

    2015-07-01

    The paper describes the results of optimization of magnetic response for highly stable bio-functionalize magnetic nanoparticles dispersion. Concentration of gelatin during in situ co-precipitation synthesis was varied from 8, 23 and 48 mg/mL to optimize magnetic properties. This variation results in a change in crystallite size from 10.3 to 7.8 ± 0.1 nm. TEM measurement of G3 sample shows highly crystalline spherical nanoparticles with a mean diameter of 7.2 ± 0.2 nm and diameter distribution (σ) of 0.27. FTIR spectra shows a shift of 22 cm(-1) at C=O stretching with absence of N-H stretching confirming the chemical binding of gelatin on magnetic nanoparticles. The concept of lone pair electron of the amide group explains the mechanism of binding. TGA shows 32.8-25.2% weight loss at 350 °C temperature substantiating decomposition of chemically bind gelatin. The magnetic response shows that for 8 mg/mL concentration of gelatin, the initial susceptibility and saturation magnetization is the maximum. The cytotoxicity of G3 sample was assessed in Normal Rat Kidney Epithelial Cells (NRK Line) by MTT assay. Results show an increase in viability for all concentrations, the indicative probability of a stimulating action of these particles in the nontoxic range. This shows the potential of this technique for biological applications as the coated particles are (i) superparamagnetic (ii) highly stable in physiological media (iii) possibility of attaching other drug with free functional group of gelatin and (iv) non-toxic.

  10. Magnetic Separation Dynamics of Colloidal Magnetic Nanoparticles

    SciTech Connect

    Kaur, M.; Huijin Zhang,; You Qiang,

    2013-01-01

    Surface functionalized magnetic nanoparticles (MNPs) are appealing candidates for analytical separation of heavy metal ions from waste water and separation of actinides from spent nuclear fuel. This work studies the separation dynamics and investigates the appropriate magnetic-field gradients. A dynamic study of colloidal MNPs was performed for steady-state flow. Measurements were conducted to record the separation time of particles as a function of magnetic field gradient. The drag and magnetic forces play a significant role on the separation time. A drop in saturation magnetization and variation of particle size occurs after surface functionalization of the MNPs; these are the primary factors that affect the separation time and velocity of the MNPs. The experimental results are correlated to a theoretical one-dimensional model.

  11. Modeling and simulation of magnetic nanoparticle sensor.

    PubMed

    Makiranta, Jarkko; Lekkala, Jukka

    2005-01-01

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

  12. Magnetism in nanoparticles: tuning properties with coatings.

    PubMed

    Crespo, Patricia; de la Presa, Patricia; Marín, Pilar; Multigner, Marta; Alonso, José María; Rivero, Guillermo; Yndurain, Félix; González-Calbet, José María; Hernando, Antonio

    2013-12-04

    This paper reviews the effect of organic and inorganic coatings on magnetic nanoparticles. The ferromagnetic-like behaviour observed in nanoparticles constituted by materials which are non-magnetic in bulk is analysed for two cases: (a) Pd and Pt nanoparticles, formed by substances close to the onset of ferromagnetism, and (b) Au and ZnO nanoparticles, which were found to be surprisingly magnetic at the nanoscale when coated by organic surfactants. An overview of theories accounting for this unexpected magnetism, induced by the nanosize influence, is presented. In addition, the effect of coating magnetic nanoparticles with biocompatible metals, oxides or organic molecules is also reviewed, focusing on their applications.

  13. Development of a Magnetic Attachment Method for Bionic Eye Applications.

    PubMed

    Fox, Kate; Meffin, Hamish; Burns, Owen; Abbott, Carla J; Allen, Penelope J; Opie, Nicholas L; McGowan, Ceara; Yeoh, Jonathan; Ahnood, Arman; Luu, Chi D; Cicione, Rosemary; Saunders, Alexia L; McPhedran, Michelle; Cardamone, Lisa; Villalobos, Joel; Garrett, David J; Nayagam, David A X; Apollo, Nicholas V; Ganesan, Kumaravelu; Shivdasani, Mohit N; Stacey, Alastair; Escudie, Mathilde; Lichter, Samantha; Shepherd, Robert K; Prawer, Steven

    2016-03-01

    Successful visual prostheses require stable, long-term attachment. Epiretinal prostheses, in particular, require attachment methods to fix the prosthesis onto the retina. The most common method is fixation with a retinal tack; however, tacks cause retinal trauma, and surgical proficiency is important to ensure optimal placement of the prosthesis near the macula. Accordingly, alternate attachment methods are required. In this study, we detail a novel method of magnetic attachment for an epiretinal prosthesis using two prostheses components positioned on opposing sides of the retina. The magnetic attachment technique was piloted in a feline animal model (chronic, nonrecovery implantation). We also detail a new method to reliably control the magnet coupling force using heat. It was found that the force exerted upon the tissue that separates the two components could be minimized as the measured force is proportionately smaller at the working distance. We thus detail, for the first time, a surgical method using customized magnets to position and affix an epiretinal prosthesis on the retina. The position of the epiretinal prosthesis is reliable, and its location on the retina is accurately controlled by the placement of a secondary magnet in the suprachoroidal location. The electrode position above the retina is less than 50 microns at the center of the device, although there were pressure points seen at the two edges due to curvature misalignment. The degree of retinal compression found in this study was unacceptably high; nevertheless, the normal structure of the retina remained intact under the electrodes.

  14. [Development and transition of magnetic attachments--a literature review].

    PubMed

    Hirata, M

    1997-12-01

    In the 1950 s, a new method of using magnets for the retainers of removable partial dentures (RPDs) was developed. It utilized magnetic attractive force instead of mechanical friction. However, the magnets used in those days were Alnico, Ferrite and/or Pt-Cobalt magnets and their retentive force was not strong enough to stabilize the dentures. Therefore, they gradually went out of use. In the middle of the 1970 s, Samarium Cobalt magnets, which have strong magnetic characteristics, were developed and introduced into dental field. In 1976, Sasaki first applied the samarium cobalt magnets to the retainers of PPDs. While in 1981, Mizutani, et al. first used well-fitted ferromagnetic alloy and the magnet for the purpose of stabilizing the RPD. Since then, many researchers have developed devices such as the magnetic retainer and the closed field magnetic attachment placed on the market in 1992. Now, as for the popular retainer of RPD, one can easily use a smaller yet stronger magnetic attachment which uses Neodium rather than Samarium Cobalt magnet.

  15. Corrosion of coupled metals in a dental magnetic attachment system.

    PubMed

    Iimuro, F T; Yoneyama, T; Okuno, O

    1993-12-01

    Implants and magnetic attachments are becoming widespread in dental treatment. Their associated use, implants and magnetic attachments, can be seen often too. In those cases, it is difficult to avoid coupling of different metals. The corrosion behavior of the metals is expected to be different depending on whether it is found in an isolated or a coupled condition. Potential corrosion couples in a dental magnetic attachment system among titanium, ferromagnetic stainless steel, gold alloy type IV, and gold-silver-palladium alloy were studied by an immersion test in 1% lactic acid for 7 days and potential/current density curves were measured. Corrosion of titanium and ferromagnetic stainless steel seemed to be accelerated by coupling with gold alloys or gold-silver-palladium alloys. On the other hand, the corrosion amount of gold alloy and gold-silver-palladium alloys were attenuated by coupling.

  16. The role of ROS generation from magnetic nanoparticles in an alternating magnetic field on cytotoxicity

    PubMed Central

    Wydra, Robert J.; Rychahou, Piotr G.; Evers, B. Mark; Anderson, Kimberly W.; Dziubla, Thomas D.; Hilt, J. Zach

    2015-01-01

    Monosaccharide coated iron oxide nanoparticles were developed to selectively target colon cancer cell lines for magnetically mediated energy delivery therapy. The nanoparticles were prepared using a coupling reaction to attach the glucose functional group to the iron oxide core, and functionality was confirmed with physicochemical characterization techniques. The targeted nanoparticles were internalized into CT26 cells at a greater extent than non-targeted nanoparticles, and the nanoparticles were shown to be localized within lysosomes. Cells with internalized nanoparticles were exposed to an AMF to determine the potential to delivery therapy. Cellular ROS generation and apoptotic cell death was enhanced with field exposure. The nanoparticle coatings inhibit the Fenton-like surface generation of ROS suggesting a thermal or mechanical effect is more likely the source of the intracellular effect. PMID:26143604

  17. [Magnetic nanoparticles and intracellular delivery of biopolymers].

    PubMed

    Kornev, A A; Dubina, M V

    2014-03-01

    The basic methods of intracellular delivery of biopolymers are present in this review. The structure and synthesis of magnetic nanoparticles, their stabilizing surfactants are described. The examples of the interaction of nanoparticles with biopolymers such as nucleic acids and proteins are considered. The final part of the review is devoted to problems physiology and biocompatibility of magnetic nanoparticles.

  18. 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.

  19. Scaling relations for magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Landeros, P.; Escrig, J.; Altbir, D.; Laroze, D.; D'Albuquerque E Castro, J.; Vargas, P.

    2005-03-01

    A detailed investigation of the scaling relations recently proposed [J. d’Albuquerque e Castro, D. Altbir, J. C. Retamal, and P. Vargas, Phys. Rev. Lett. 88, 237202 (2002)] to study the magnetic properties of nanoparticles is presented. Analytical expressions for the total energy of three characteristic internal configurations of the particles are obtained, in terms of which the behavior of the magnetic phase diagram for those particles upon scaling of the exchange interaction is discussed. The exponent η in scaling relations is shown to be dependent on the geometry of the vortex core, and results for specific cases are presented.

  20. Modeling drug release from functionalized magnetic nanoparticles actuated by non-heating low frequency magnetic field

    NASA Astrophysics Data System (ADS)

    Golovin, Y.; Golovin, D.; Klyachko, N.; Majouga, A.; Kabanov, A.

    2017-02-01

    Various plausible acceleration mechanisms of drug release from nanocarriers composed of a single-domain magnetic nanoparticle core with attached long macromolecule chains activated by low frequency non-heating alternating magnetic field (AMF) are discussed. The most important system characteristics affecting the AMF exposure impact are determined. Impact of several reasonable mechanisms is estimated analytically or obtained using numerical modeling. Some conditions providing manifold release acceleration as a result from exposure in AMF are found.

  1. Applications of Bacterial Magnetic Nanoparticles in Nanobiotechnology.

    PubMed

    Chen, Chuanfang; Wang, Pingping; Li, Linlin

    2016-03-01

    The bacterial magnetic nanoparticle (BMP) has been well researched in nanobiotechnology as a new magnetic crystal. The BMPs are extracted from magnetotactic bacteria and under precise biological control. Compared with engineered magnetic nanoparticles synthesized by chemical approaches, BMPs have the properties of large production, monodispersity, high crystallinity, and close-to-bulk magnetization, which enable BMPs to be the highly promising magnetic nanoparticles for nanobiotechnology. In this paper, we review the biomedical applications of BMPs in magnetic hyperthermia, drug treatment with tumour and bioseparation. In addition, the biodistribution and toxicity are also reviewed.

  2. Magnetic Nanoparticles in Non-magnetic CNTs and Graphene

    NASA Astrophysics Data System (ADS)

    Kayondo, Moses; Seifu, Dereje

    Magnetic nanoparticles were embedded in non-magnetic CNTs and graphene matrix to incorporate all the advantages and the unique properties of CNTs and graphene. Composites of CNTs and graphene with magnetic nanoparticles may offer new opportunities for a wide variety of potential applications such as magnetic data storage, magnetic force microscopy tip, electromagnetic interference shields, thermally conductive films, reinforced polymer composites, transparent electrodes for displays, solar cells, gas sensors, magnetic nanofluids, and magnetically guided drug delivery systems. Magnetic nanoparticles coated CNTs can also be used as an electrode in lithium ion battery to replace graphite because of the higher theoretical capacity. Graphene nanocomposites, coated with magnetic sensitive nanoparticles, have demonstrated enhanced magnetic property. We would like to acknowledge support by NSF-MRI-DMR-1337339.

  3. Recent Advances in the Application of Magnetic Nanoparticles as a Support for Homogeneous Catalysts

    PubMed Central

    Govan, Joseph; Gun’ko, Yurii K.

    2014-01-01

    Magnetic nanoparticles are a highly valuable substrate for the attachment of homogeneous inorganic and organic containing catalysts. This review deals with the very recent main advances in the development of various nanocatalytic systems by the immobilisation of homogeneous catalysts onto magnetic nanoparticles. We discuss magnetic core shell nanostructures (e.g., silica or polymer coated magnetic nanoparticles) as substrates for catalyst immobilisation. Then we consider magnetic nanoparticles bound to inorganic catalytic mesoporous structures as well as metal organic frameworks. Binding of catalytically active small organic molecules and polymers are also reviewed. After that we briefly deliberate on the binding of enzymes to magnetic nanocomposites and the corresponding enzymatic catalysis. Finally, we draw conclusions and present a future outlook for the further development of new catalytic systems which are immobilised onto magnetic nanoparticles. PMID:28344220

  4. Fighting cancer with magnetic nanoparticles and immunotherapy

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

  5. Materials science: Magnetic nanoparticles line up

    NASA Astrophysics Data System (ADS)

    Faivre, Damien; Bennet, Mathieu

    2016-07-01

    Certain bacteria contain strings of magnetic nanoparticles and therefore align with magnetic fields. Inspired by these natural structures, researchers have now fabricated synthetic one-dimensional arrays of such particles.

  6. Tumour homing and therapeutic effect of colloidal nanoparticles depend on the number of attached antibodies

    NASA Astrophysics Data System (ADS)

    Colombo, Miriam; Fiandra, Luisa; Alessio, Giulia; Mazzucchelli, Serena; Nebuloni, Manuela; de Palma, Clara; Kantner, Karsten; Pelaz, Beatriz; Rotem, Rany; Corsi, Fabio; Parak, Wolfgang J.; Prosperi, Davide

    2016-12-01

    Active targeting of nanoparticles to tumours can be achieved by conjugation with specific antibodies. Specific active targeting of the HER2 receptor is demonstrated in vitro and in vivo with a subcutaneous MCF-7 breast cancer mouse model with trastuzumab-functionalized gold nanoparticles. The number of attached antibodies per nanoparticle was precisely controlled in a way that each nanoparticle was conjugated with either exactly one or exactly two antibodies. As expected, in vitro we found a moderate increase in targeting efficiency of nanoparticles with two instead of just one antibody attached per nanoparticle. However, the in vivo data demonstrate that best effect is obtained for nanoparticles with only exactly one antibody. There is indication that this is based on a size-related effect. These results highlight the importance of precisely controlling the ligand density on the nanoparticle surface for optimizing active targeting, and that less antibodies can exhibit more effect.

  7. Tumour homing and therapeutic effect of colloidal nanoparticles depend on the number of attached antibodies

    PubMed Central

    Colombo, Miriam; Fiandra, Luisa; Alessio, Giulia; Mazzucchelli, Serena; Nebuloni, Manuela; De Palma, Clara; Kantner, Karsten; Pelaz, Beatriz; Rotem, Rany; Corsi, Fabio; Parak, Wolfgang J.; Prosperi, Davide

    2016-01-01

    Active targeting of nanoparticles to tumours can be achieved by conjugation with specific antibodies. Specific active targeting of the HER2 receptor is demonstrated in vitro and in vivo with a subcutaneous MCF-7 breast cancer mouse model with trastuzumab-functionalized gold nanoparticles. The number of attached antibodies per nanoparticle was precisely controlled in a way that each nanoparticle was conjugated with either exactly one or exactly two antibodies. As expected, in vitro we found a moderate increase in targeting efficiency of nanoparticles with two instead of just one antibody attached per nanoparticle. However, the in vivo data demonstrate that best effect is obtained for nanoparticles with only exactly one antibody. There is indication that this is based on a size-related effect. These results highlight the importance of precisely controlling the ligand density on the nanoparticle surface for optimizing active targeting, and that less antibodies can exhibit more effect. PMID:27991503

  8. Building high-coverage monolayers of covalently bound magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Williams, Mackenzie G.; Teplyakov, Andrew V.

    2016-12-01

    This work presents an approach for producing a high-coverage single monolayer of magnetic nanoparticles using "click chemistry" between complementarily functionalized nanoparticles and a flat substrate. This method highlights essential aspects of the functionalization scheme for substrate surface and nanoparticles to produce exceptionally high surface coverage without sacrificing selectivity or control over the layer produced. The deposition of one single layer of magnetic particles without agglomeration, over a large area, with a nearly 100% coverage is confirmed by electron microscopy. Spectroscopic techniques, supplemented by computational predictions, are used to interrogate the chemistry of the attachment and to confirm covalent binding, rather than attachment through self-assembly or weak van der Waals bonding. Density functional theory calculations for the surface intermediate of this copper-catalyzed process provide mechanistic insight into the effects of the functionalization scheme on surface coverage. Based on this analysis, it appears that steric limitations of the intermediate structure affect nanoparticle coverage on a flat solid substrate; however, this can be overcome by designing a functionalization scheme in such a way that the copper-based intermediate is formed on the spherical nanoparticles instead. This observation can be carried over to other approaches for creating highly controlled single- or multilayered nanostructures of a wide range of materials to result in high coverage and possibly, conformal filling.

  9. 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.

  10. 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.

  11. Bioinspired synthesis of magnetic nanoparticles

    SciTech Connect

    David, Anand

    2009-01-01

    The synthesis of magnetic nanoparticles has long been an area of active research. Magnetic nanoparticles can be used in a wide variety of applications such as magnetic inks, magnetic memory devices, drug delivery, magnetic resonance imaging (MRI) contrast agents, and pathogen detection in foods. In applications such as MRI, particle uniformity is particularly crucial, as is the magnetic response of the particles. Uniform magnetic particles with good magnetic properties are therefore required. One particularly effective technique for synthesizing nanoparticles involves biomineralization, which is a naturally occurring process that can produce highly complex nanostructures. Also, the technique involves mild conditions (ambient temperature and close to neutral pH) that make this approach suitable for a wide variety of materials. The term 'bioinspired' is important because biomineralization research is inspired by the naturally occurring process, which occurs in certain microorganisms called 'magnetotactic bacteria'. Magnetotactic bacteria use biomineralization proteins to produce magnetite crystals having very good uniformity in size and morphology. The bacteria use these magnetic particles to navigate according to external magnetic fields. Because these bacteria synthesize high quality crystals, research has focused on imitating aspects of this biomineralization in vitro. In particular, a biomineralization iron-binding protein found in a certain species of magnetotactic bacteria, magnetospirillum magneticum, AMB-1, has been extracted and used for in vitro magnetite synthesis; Pluronic F127 gel was used to increase the viscosity of the reaction medium to better mimic the conditions in the bacteria. It was shown that the biomineralization protein mms6 was able to facilitate uniform magnetite synthesis. In addition, a similar biomineralization process using mms6 and a shorter version of this protein, C25, has been used to synthesize cobalt ferrite particles. The overall

  12. Magnetic Nanoparticles in Cancer Theranostics.

    PubMed

    Gobbo, Oliviero L; Sjaastad, Kristine; Radomski, Marek W; Volkov, Yuri; Prina-Mello, Adriele

    2015-01-01

    In a report from 2008, The International Agency for Research on Cancer predicted a tripled cancer incidence from 1975, projecting a possible 13-17 million cancer deaths worldwide by 2030. While new treatments are evolving and reaching approval for different cancer types, the main prevention of cancer mortality is through early diagnosis, detection and treatment of malignant cell growth. The last decades have seen a development of new imaging techniques now in widespread clinical use. The development of nano-imaging through fluorescent imaging and magnetic resonance imaging (MRI) has the potential to detect and diagnose cancer at an earlier stage than with current imaging methods. The characteristic properties of nanoparticles result in their theranostic potential allowing for simultaneous detection of and treatment of the disease. This review provides state of the art of the nanotechnological applications for cancer therapy. Furthermore, it advances a novel concept of personalized nanomedical theranostic therapy using iron oxide magnetic nanoparticles in conjunction with MRI imaging. Regulatory and industrial perspectives are also included to outline future perspectives in nanotechnological cancer research.

  13. Magnetic Nanoparticles in Cancer Theranostics

    PubMed Central

    Gobbo, Oliviero L.; Sjaastad, Kristine; Radomski, Marek W.; Volkov, Yuri; Prina-Mello, Adriele

    2015-01-01

    In a report from 2008, The International Agency for Research on Cancer predicted a tripled cancer incidence from 1975, projecting a possible 13-17 million cancer deaths worldwide by 2030. While new treatments are evolving and reaching approval for different cancer types, the main prevention of cancer mortality is through early diagnosis, detection and treatment of malignant cell growth. The last decades have seen a development of new imaging techniques now in widespread clinical use. The development of nano-imaging through fluorescent imaging and magnetic resonance imaging (MRI) has the potential to detect and diagnose cancer at an earlier stage than with current imaging methods. The characteristic properties of nanoparticles result in their theranostic potential allowing for simultaneous detection of and treatment of the disease. This review provides state of the art of the nanotechnological applications for cancer therapy. Furthermore, it advances a novel concept of personalized nanomedical theranostic therapy using iron oxide magnetic nanoparticles in conjunction with MRI imaging. Regulatory and industrial perspectives are also included to outline future perspectives in nanotechnological cancer research. PMID:26379790

  14. Magnetic Characterization of Ferrite Nanoparticles

    NASA Astrophysics Data System (ADS)

    Bryan, Matthew; Sokol, Paul; Gumina, Greg; Bronstein, Lyudmila; Dragnea, Bogdan

    2011-03-01

    Magnetic nanoparticles (NPs) of different compositions (FeO/ Fe 3 O4 , g- Fe 2 O3 , FePt, and CoFe 2 O4) have been synthesized using high temperature organometallic routes described elsewhere. NPs (16.6 nm in diameter) of a mixed FeO/ Fe 3 O4 (wuestite/magnetite) composition were prepared by thermal decomposition or iron oleate in the presence of oleic acid as a surfactant in dodocane at 370C in argon atmosphere. After the thermal treatment of the reaction solution at 200 C under air for 2 hours these NPs are transformed into maghemite (g- Fe 2 O3) , the magnetization of which is significantly enhanced. NPs of CoFe 2 O4 (8 nm) have been prepared by simultaneous decomposition of Co(II) and Fe(III) acetylacetonates in the presence of oleic acid and oleylamine. The X-ray diffraction profile of these NPs is characteristic of cobalt ferrite. Alternatively, alloyed 1.8 nm FePt NPs prepared by simultaneous decomposition of Fe and Pt acetylacetonates in the reductive environment demonstrate a completely disordered structure, which is reflected in their magnetic properties. SQUID magnetometry was used to measure the magnetization of NPs at high and low temperatures. Zero-field cooling and field-cooling measurements were taken to demonstrate superparamagnetic behavior and an associated blocking temperature.

  15. Platinum dendritic nanoparticles with magnetic behavior

    SciTech Connect

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

    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.

  16. In vivo heating of magnetic nanoparticles in alternating magnetic field.

    PubMed

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

    2004-08-01

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

  17. [Magnetic nanoparticles as tools for cell therapy].

    PubMed

    Wilhelm, Claire; Gazeau, Florence

    2012-01-01

    Labelling living cells with magnetic nanoparticles creates opportunities for numerous biomedical applications such as Magnetic Resonance Imaging (MRI) cell tracking, cell manipulation, cell patterning for tissue engineering and magnetically-assisted cell delivery. The unique advantage of magnetic-based methods is to activate or monitor cell behavior by a remote stimulus, the magnetic field. Cell labelling methods using superparamagnetic nanoparticles have been widely developed, showing no adverse effect on cell proliferation and functionalities while conferring magnetic properties to various cell types. This paper first describes how cells can become responsive to magnetic field by safely internalizing magnetic nanoparticles. We next show how magnetic cells can be detected by MRI, giving the opportunity for non-invasive in vivo monitoring of cell migration. We exemplify the fact that MRI cell tracking has become a method of choice to follow the fate of administrated cells in cell therapy assay, whether the cells are grafted locally or administrated in the circulation. Finally we give different examples of magnetic manipulation of cells and their applications to regenerative medicine. Magnetic cell manipulation are forecasted to be more and more developed, in order to improve tissue engineering technique and assist cell-based therapies. Owing to the clinical approval of iron-oxide nanoparticles as MRI contrast agent, there is no major obstacle in the translation to human clinics of the magnetic methods summarized in this paper.

  18. Direct attachment of nanoparticle cargo to Salmonella typhimurium membranes designed for combination bacteriotherapy against tumors.

    PubMed

    Kazmierczak, Robert; Choe, Elizabeth; Sinclair, Jared; Eisenstark, Abraham

    2015-01-01

    Nanoparticle technology is an emerging approach to resolve difficult-to-manage internal diseases. It is highly regarded, in particular, for medical use in treatment of cancer due to the innate ability of certain nanoparticles to accumulate in the porous environment of tumors and to be toxic to cancer cells. However, the therapeutic success of nanoparticles is limited by the technical difficulty of fully penetrating and thus attacking the tumor. Additionally, while nanoparticles possess seeming-specificity due to the unique physiological properties of tumors themselves, it is difficult to tailor the delivery of nanoparticles or drugs in other models, such as use in cardiac disease, to the specific target. Thus, a need for delivery systems that will accurately and precisely bring nanoparticles carrying drug payloads to their intended sites currently exists. Our solution to this engineering challenge is to load such nanoparticles onto a biological "mailman" (a novel, nontoxic, therapeutic strain of Salmonella typhimurium engineered to preferentially and precisely seek out, penetrate, and hinder prostate cancer cells as the biological delivery system) that will deliver the therapeutics to a target site. In this chapter, we describe two methods that establish proof-of-concept for our cargo loading and delivery system by attaching nanoparticles to the Salmonella membrane. The first method (Subheading 1.1) describes association of sucrose-conjugated gold nanoparticles to the surface of Salmonella bacteria. The second method (Subheading 1.2) biotinylates the native Salmonella membrane to attach streptavidin-conjugated fluorophores as example nanoparticle cargo, with an alternative method (expression of membrane bound biotin target sites using autodisplay plasmid vectors) that increases the concentration of biotin on the membrane surface for streptavidin-conjugated nanoparticle attachment. By directly attaching the fluorophores to our bacterial vector through biocompatible

  19. Magnetic nanoparticle-based cancer therapy

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  20. Understanding the Role of Solvation Forces on the Preferential Attachment of Nanoparticles in Liquid

    SciTech Connect

    Welch, David A.; Woehl, Taylor J.; Park, Chiwoo; Faller, Roland; Evans, James E.; Browning, Nigel D.

    2016-01-20

    Optimization of colloidal nanoparticle synthesis techniques requires an understanding of underlying particle growth mechanisms. Non-classical growth mechanisms are particularly important as they affect nanoparticle size and shape distributions which in turn influence functional properties. For example, preferential attachment of nanoparticles is known to lead to the formation of mesocrystals, although the formation mechanism is currently not well understood. Here we employ in situ liquid cell scanning transmission electron microscopy (STEM) and steered molecular dynamics (SMD) simulations to demonstrate that the experimentally observed preference for end-to-end attachment of silver nanorods is a result of weaker solvation forces occurring at rod ends. SMD reveals that when the side of a nanorod approaches another rod, perturbation in the surface bound water at the nanorod surface creates significant energy barriers to attachment. Additionally, rod morphology (i.e. facet shape) effects can explain the majority of the side attachment effects that are observed experimentally.

  1. Understanding the Role of Solvation Forces on the Preferential Attachment of Nanoparticles in Liquid

    SciTech Connect

    Welch, David A.; Woehl, Taylor J.; Park, Chiwoo; Faller, Roland; Evans, James E.; Browning, Nigel D.

    2015-11-20

    We discuss optimization of colloidal nanoparticle synthesis techniques, which requires an understanding of underlying particle growth mechanisms. Nonclassical growth mechanisms are particularly important as they affect nanoparticle size and shape distributions, which in turn influence functional properties. For example, preferential attachment of nanoparticles is known to lead to the formation of mesocrystals, although the formation mechanism is currently not well-understood. Here we employ in situ liquid cell scanning transmission electron microscopy and steered molecular dynamics (SMD) simulations to demonstrate that the experimentally observed preference for end-to-end attachment of silver nanorods is a result of weaker solvation forces occurring at rod ends. In conclusion, SMD reveals that when the side of a nanorod approaches another rod, perturbation in the surface-bound water at the nanorod surface creates significant energy barriers to attachment. Additionally, rod morphology (i.e., facet shape) effects can explain the majority of the side attachment effects that are observed experimentally.

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

    PubMed

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

    2014-11-01

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

  3. Magnetic nanoparticles in magnetic resonance imaging and diagnostics.

    PubMed

    Rümenapp, Christine; Gleich, Bernhard; Haase, Axel

    2012-05-01

    Magnetic nanoparticles are useful as contrast agents for magnetic resonance imaging (MRI). Paramagnetic contrast agents have been used for a long time, but more recently superparamagnetic iron oxide nanoparticles (SPIOs) have been discovered to influence MRI contrast as well. In contrast to paramagnetic contrast agents, SPIOs can be functionalized and size-tailored in order to adapt to various kinds of soft tissues. Although both types of contrast agents have a inducible magnetization, their mechanisms of influence on spin-spin and spin-lattice relaxation of protons are different. A special emphasis on the basic magnetism of nanoparticles and their structures as well as on the principle of nuclear magnetic resonance is made. Examples of different contrast-enhanced magnetic resonance images are given. The potential use of magnetic nanoparticles as diagnostic tracers is explored. Additionally, SPIOs can be used in diagnostic magnetic resonance, since the spin relaxation time of water protons differs, whether magnetic nanoparticles are bound to a target or not.

  4. Heating efficiency in magnetic nanoparticle hyperthermia

    NASA Astrophysics Data System (ADS)

    Deatsch, Alison E.; Evans, Benjamin A.

    2014-03-01

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

  5. Magnetic induced heating of nanoparticle solutions

    SciTech Connect

    Murph, S. Hunyadi; Brown, M.; Coopersmith, K.; Fulmer, S.; Sessions, H.; Ali, M.

    2016-12-02

    Magnetic induced heating of nanoparticles (NP) provides a useful advantage for many energy transfer applications. This study aims to gain an understanding of the key parameters responsible for maximizing the energy transfer leading to nanoparticle heating through the use of simulations and experimental results. It was found that magnetic field strength, NP concentration, NP composition, and coil size can be controlled to generate accurate temperature profiles in NP aqueous solutions.

  6. Magnetic force microscopy of superparamagnetic nanoparticles.

    PubMed

    Schreiber, Sharon; Savla, Mayur; Pelekhov, Denis V; Iscru, Daniel F; Selcu, Camelia; Hammel, P Chris; Agarwal, Gunjan

    2008-02-01

    The use of magnetic force microscopy (MFM) to detect probe-sample interactions from superparamagnetic nanoparticles in vitro in ambient atmospheric conditions is reported here. By using both magnetic and nonmagnetic probes in dynamic lift-mode imaging and by controlling the direction and magnitude of the external magnetic field applied to the samples, it is possible to detect and identify the presence of superparamagnetic nanoparticles. The experimental results shown here are in agreement with the estimated sensitivity of the MFM technique. The potential and challenges for localizing nanoscale magnetic domains in biological samples is discussed.

  7. Prospects for nanoparticle-based permanent magnets

    SciTech Connect

    Balamurugan, B; Sellmyer, DJ; Hadjipanayis, GC; Skomski, R

    2012-09-01

    Magnetic nanoparticles smaller than similar to 15 nm in diameter and with high magnetocrystalline anisotropies K-1 >= 1 MJ m(-3) can be used as building blocks for next-generation permanent magnets. Advances in processing steps are discussed, such as self-assembly, alignment of the easy axes and appropriate nanostructuring that will enable the fabrication of densely packed nanopartide assemblies with improved permanent-magnet properties. This study also proposes an idealized nanocomposite structure for nanoparticle-based future permanent magnets with enhanced energy products. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  8. Development of Novel Magnetic Nanoparticles for Hyperthermia Cancer Therapy

    PubMed Central

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

    2013-01-01

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

  9. 3-T MRI safety assessments of magnetic dental attachments and castable magnetic alloys

    PubMed Central

    Miyata, K; Abe, Y; Ishii, T; Ishigami, T; Ohtani, K; Nagai, E; Ohyama, T; Umekawa, Y; Nakabayashi, S

    2015-01-01

    Objectives: To assess the safety of different magnetic dental attachments during 3-T MRI according to the American Society for Testing and Materials F2182-09 and F2052-06e1 standard testing methods and to develop a method to determine MRI compatibility by measuring magnetically induced torque. Methods: The temperature elevations, magnetically induced forces and torques of a ferromagnetic stainless steel keeper, a coping comprising a keeper and a cast magnetic alloy coping were measured on MRI systems. Results: The coping comprising a keeper demonstrated the maximum temperature increase (1.42 °C) for the whole-body-averaged specific absorption rate and was calculated as 2.1 W kg−1 with the saline phantom. All deflection angles exceeded 45°. The cast magnetic alloy coping had the greatest deflection force (0.33 N) during 3-T MRI and torque (1.015 mN m) during 0.3-T MRI. Conclusions: The tested devices showed minimal radiofrequency (RF)-induced heating in a 3-T MR environment, but the cast magnetic alloy coping showed a magnetically induced deflection force and torque approximately eight times that of the keepers. For safety, magnetic dental attachments should be inspected before and after MRI and large prostheses containing cast magnetic alloy should be removed. Although magnetic dental attachments may pose no great risk of RF-induced heating or magnetically induced torque during 3-T MRI, their magnetically induced deflection forces tended to exceed acceptable limits. Therefore, the inspection of such devices before and after MRI is important for patient safety. PMID:25785821

  10. Blood clot detection using magnetic nanoparticles.

    PubMed

    Khurshid, Hafsa; Friedman, Bruce; Berwin, Brent; Shi, Yipeng; Ness, Dylan B; Weaver, John B

    2017-05-01

    Deep vein thrombosis, the development of blood clots in the peripheral veins, is a very serious, life threatening condition that is prevalent in the elderly. To deliver proper treatment that enhances the survival rate, it is very important to detect thrombi early and at the point of care. We explored the ability of magnetic particle spectroscopy (MSB) to detect thrombus via specific binding of aptamer functionalized magnetic nanoparticles with the blood clot. MSB uses the harmonics produced by nanoparticles in an alternating magnetic field to measure the rotational freedom and, therefore, the bound state of the nanoparticles. The nanoparticles' relaxation time for Brownian rotation increases when bound [A.M. Rauwerdink and J. B. Weaver, Appl. Phys. Lett. 96, 1 (2010)]. The relaxation time can therefore be used to characterize the nanoparticle binding to thrombin in the blood clot. For longer relaxation times, the approach to saturation is more gradual reducing the higher harmonics and the harmonic ratio. The harmonic ratios of nanoparticles conjugated with anti-thrombin aptamers (ATP) decrease significantly over time with blood clot present in the sample medium, compared with nanoparticles without ATP. Moreover, the blood clot removed from the sample medium produced a significant MSB signal, indicating the nanoparticles are immobilized on the clot. Our results show that MSB could be a very useful non-invasive, quick tool to detect blood clots at the point of care so proper treatment can be used to reduce the risks inherent in deep vein thrombosis.

  11. Neural stem cells harvested from live brains by antibody-conjugated magnetic nanoparticles.

    PubMed

    Lui, C N P; Tsui, Y P; Ho, A S L; Shum, D K Y; Chan, Y S; Wu, C T; Li, H W; Tsang, S C Edman; Yung, K K L

    2013-11-18

    It stems from the magnetism: The extraction of stem/progenitor cells from the brain of live animals is possible using antibodies conjugated to magnetic nanoparticles (Ab-MNPs). The Ab-MNPs are introduced to a rat's brain with a superfine micro-syringe. The stem cells attach to the Ab-MNPs and are magnetically isolated and removed. They can develop into neurospheres and differentiate into different types of cells outside the subject body. The rat remains alive and healthy.

  12. Using polymers to make up magnetic nanoparticles for biomedicine.

    PubMed

    Chanana, Munish; Mao, Zhengwei; Wang, Dayang

    2009-12-01

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

  13. 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

  14. Approaches for modeling magnetic nanoparticle dynamics

    PubMed Central

    Reeves, Daniel B; Weaver, John B

    2014-01-01

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

  15. Hydrophobic interactions increase attachment of gum Arabic- and PVP-coated Ag nanoparticles to hydrophobic surfaces.

    PubMed

    Song, Jee Eun; Phenrat, Tanapon; Marinakos, Stella; Xiao, Yao; Liu, Jie; Wiesner, Mark R; Tilton, Robert D; Lowry, Gregory V

    2011-07-15

    A fundamental understanding of attachment of surface-coated nanoparticles (NPs) is essential to predict the distribution and potential risks of NPs in the environment. Column deposition studies were used to examine the effect of surface-coating hydrophobicity on NP attachment to collector surfaces in mixtures with varying ratios of octadecylichlorosilane (OTS)-coated (hydrophobic) glass beads and clean silica (hydrophilic) glass beads. Silver nanoparticles (AgNPs) coated with organic coatings of varying hydrophobicity, including citrate, polyvinylpyrrolidone (PVP), and gum arabic (GA), were used. The attachment efficiencies of GA and PVP AgNPs increased by 2- and 4-fold, respectively, for OTS-coated glass beads compared to clean glass beads. Citrate AgNPs showed no substantial change in attachment efficiency for hydrophobic compared to hydrophilic surfaces. The attachment efficiency of PVP-, GA-, and citrate-coated AgNPs to hydrophobic collector surfaces correlated with the relative hydrophobicity of the coatings. The differences in the observed attachment efficiencies among AgNPs could not be explained by classical DLVO, suggesting that hydrophobic interactions between AgNPs and OTS-coated glass beads were responsible for the increase in attachment of surface-coated AgNPs with greater hydrophobicity. This study indicates that the overall attachment efficiency of AgNPs will be influenced by the hydrophobicity of the NP coating and the fraction of hydrophobic surfaces in the environment.

  16. Blood clot detection using magnetic nanoparticles

    PubMed Central

    Khurshid, Hafsa; Friedman, Bruce; Berwin, Brent; Shi, Yipeng; Ness, Dylan B.; Weaver, John B.

    2017-01-01

    Deep vein thrombosis, the development of blood clots in the peripheral veins, is a very serious, life threatening condition that is prevalent in the elderly. To deliver proper treatment that enhances the survival rate, it is very important to detect thrombi early and at the point of care. We explored the ability of magnetic particle spectroscopy (MSB) to detect thrombus via specific binding of aptamer functionalized magnetic nanoparticles with the blood clot. MSB uses the harmonics produced by nanoparticles in an alternating magnetic field to measure the rotational freedom and, therefore, the bound state of the nanoparticles. The nanoparticles’ relaxation time for Brownian rotation increases when bound [A.M. Rauwerdink and J. B. Weaver, Appl. Phys. Lett. 96, 1 (2010)]. The relaxation time can therefore be used to characterize the nanoparticle binding to thrombin in the blood clot. For longer relaxation times, the approach to saturation is more gradual reducing the higher harmonics and the harmonic ratio. The harmonic ratios of nanoparticles conjugated with anti-thrombin aptamers (ATP) decrease significantly over time with blood clot present in the sample medium, compared with nanoparticles without ATP. Moreover, the blood clot removed from the sample medium produced a significant MSB signal, indicating the nanoparticles are immobilized on the clot. Our results show that MSB could be a very useful non-invasive, quick tool to detect blood clots at the point of care so proper treatment can be used to reduce the risks inherent in deep vein thrombosis. PMID:28289550

  17. Recent advances on surface engineering of magnetic iron oxide nanoparticles and their biomedical applications.

    PubMed

    Gupta, Ajay Kumar; Naregalkar, Rohan R; Vaidya, Vikas Deep; Gupta, Mona

    2007-02-01

    Magnetic nanoparticles with appropriate surface coatings are increasingly being used clinically for various biomedical applications, such as magnetic resonance imaging, hyperthermia, drug delivery, tissue repair, cell and tissue targeting and transfection. This is because of the nontoxicity and biocompatibility demand that mainly iron oxide-based materials are predominantly used, despite some attempts to develop 'more magnetic nanomaterials' based on cobalt, nickel, gadolinium and other compounds. For all these applications, the material used for surface coating of the magnetic particles must not only be nontoxic and biocompatible but also allow a targetable delivery with particle localization in a specific area. Magnetic nanoparticles can bind to drugs and an external magnetic field can be applied to trap them in the target site. By attaching the targeting molecules, such as proteins or antibodies, at particles surfaces, the latter may be directed to any cell, tissue or tumor in the body. In this review, different polymers/molecules that can be used for nanoparticle coating to stabilize the suspensions of magnetic nanoparticles under in vitro and in vivo situations are discussed. Some selected proteins/targeting ligands that could be used for derivatizing magnetic nanoparticles are also explored. We have reviewed the various biomedical applications with some of the most recent uses of magnetic nanoparticles for early detection of cancer, diabetes and atherosclerosis.

  18. Radiofrequency heating and magnetically induced displacement of dental magnetic attachments during 3.0 T MRI

    PubMed Central

    Miyata, K; Hasegawa, M; Abe, Y; Tabuchi, T; Namiki, T; Ishigami, T

    2012-01-01

    Objective The aim of this study was to estimate the risk of injury from dental magnetic attachments due to their radiofrequency (RF) heating and magnetically induced displacement during 3.0 T MRI. Methods To examine the magnetic attachments, we adopted the American Society for Testing and Materials F2182-02a and F2052-06 standards in two MRI systems (Achieva 3.0 T Nova Dual; Philips, Tokyo, Japan, and Signa HDxt 3.0 T; GE Healthcare, Milwaukee, WI). The temperature change was measured in a cylindrical keeper (GIGAUSS D600; GC, Tokyo, Japan) with coping of the casting alloy and a keeper with a dental implant at the maximum specific absorption rate (SAR) for 20 min. To measure the magnetically induced displacement force, three sizes of keepers (GIGAUSS D400, D600 and D1000) were used in deflection angle tests conducted at the point of the maximum magnetic field strength. Results Temperature elevations of both coping and implant were higher in the Signa system than in the Achieva system. The highest temperature changes in the keeper with implant and keeper with coping were 0.6 °C and 0.8 °C in the Signa system, respectively. The temperature increase did not exceed 1.0 °C at any location. The deflection angle (α) was not measurable because it exceeded 90°. GIGAUSS D400 required an extra 3.0 g load to constrain the deflection angle to less than 45°; GIGAUSS D600 and D1000 required 5.0 and 9.0 g loads, respectively. Conclusions Dental magnetic attachments pose no risk due to RF heating and magnetically induced displacement at 3.0 T MRI. However, it is necessary to confirm that these keepers are securely attached to the prosthesis before imaging. PMID:22499128

  19. Biological cell manipulation by magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Gertz, Frederick; Khitun, Alexander

    2016-02-01

    We report a manipulation of biological cells (erythrocytes) by magnetite (Fe3O4) nanoparticles in the presence of a magnetic field. The experiment was accomplished on the top of a micro-electromagnet consisting of two magnetic field generating contours. An electric current flowing through the contour(s) produces a non-uniform magnetic field, which is about 1.4 mT/μm in strength at 100 mA current in the vicinity of the current-carrying wire. In responses to the magnetic field, magnetic nanoparticles move towards the systems energy minima. In turn, magnetic nanoparticles drag biological cells in the same direction. We present experimental data showing cell manipulation through the control of electric current. This technique allows us to capture and move cells located in the vicinity (10-20 microns) of the current-carrying wires. One of the most interesting results shows a periodic motion of erythrocytes between the two conducting contours, whose frequency is controlled by an electric circuit. The obtained results demonstrate the feasibility of non-destructive cell manipulation by magnetic nanoparticles with micrometer-scale precision.

  20. 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...

  1. Dynamics of magnetic nano-particle assembly

    NASA Astrophysics Data System (ADS)

    Kondratyev, V. N.

    2010-11-01

    Ferromagnetically coupled nano-particle assembly is analyzed accounting for inter- and intra- particle electronic structures within the randomly jumping interacting moments model including quantum fluctuations due to the discrete levels and disorder. At the magnetic jump anomalies caused by quantization the magnetic state equation and phase diagram are found to indicate an existence of spinodal regions and critical points. Arrays of magnetized nano-particles with multiple magnetic response anomalies are predicted to display some specific features. In a case of weak coupling such arrays exhibit the well-separated instability regions surrounding the anomaly positions. With increasing coupling we observe further structure modification, plausibly, of bifurcation type. At strong coupling the dynamical instability region become wide while the stable regime arises as a narrow islands at small disorders. It is shown that exploring correlations of magnetic noise amplitudes represents convenient analytical tool for quantitative definition, description and study of supermagnetism, as well as self-organized criticality.

  2. 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

  3. Microfluidic biosensing systems using magnetic nanoparticles.

    PubMed

    Giouroudi, Ioanna; Keplinger, Franz

    2013-09-09

    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.

  4. 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

  5. Monodisperse Magnetic Nanoparticles for Theranostic Applications

    PubMed Central

    Ho, Don; Sun, Xiaolian; Sun, Shouheng

    2011-01-01

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

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

    PubMed

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

    2014-06-27

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

  7. Magnetic properties of ZnO nanoparticles.

    PubMed

    Garcia, M A; Merino, J M; Fernández Pinel, E; Quesada, A; de la Venta, J; Ruíz González, M L; Castro, G R; Crespo, P; Llopis, J; González-Calbet, J M; Hernando, A

    2007-06-01

    We experimentally show that it is possible to induce room-temperature ferromagnetic-like behavior in ZnO nanoparticles without doping with magnetic impurities but simply inducing an alteration of their electronic configuration. Capping ZnO nanoparticles ( approximately 10 nm size) with different organic molecules produces an alteration of their electronic configuration that depends on the particular molecule, as evidenced by photoluminescence and X-ray absorption spectroscopies and altering their magnetic properties that varies from diamagnetic to ferromagnetic-like behavior.

  8. Tuning the magnetism of ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Viñas, S. Liébana; Simeonidis, K.; Li, Z.-A.; Ma, Z.; Myrovali, E.; Makridis, A.; Sakellari, D.; Angelakeris, M.; Wiedwald, U.; Spasova, M.; Farle, M.

    2016-10-01

    The importance of magnetic interactions within an individual nanoparticle or between adjacent ones is crucial not only for the macroscopic collective magnetic behavior but for the AC magnetic heating efficiency as well. On this concept, single-(MFe2O4 where M=Fe, Co, Mn) and core-shell ferrite nanoparticles consisting of a magnetically softer (MnFe2O4) or magnetically harder (CoFe2O4) core and a magnetite (Fe3O4) shell with an overall size in the 10 nm range were synthesized and studied for their magnetic particle hyperthermia efficiency. Magnetic measurements indicate that the coating of the hard magnetic phase (CoFe2O4) by Fe3O4 provides a significant enhancement of hysteresis losses over the corresponding single-phase counterpart response, and thus results in a multiplication of the magnetic hyperthermia efficiency opening a novel pathway for high-performance, magnetic hyperthermia agents. At the same time, the existence of a biocompatible Fe3O4 outer shell, toxicologically renders these systems similar to iron-oxide ones with significantly milder side-effects.

  9. 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 μm) 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 α≥2), the Brownian motion seems not to affect the cloud behavior.

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

    NASA Astrophysics Data System (ADS)

    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 μm) 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 α ≥2), the Brownian motion seems not to affect the cloud behavior.

  11. Magnetic Properties of Magnetic Nanoparticles for Efficient Hyperthermia

    PubMed Central

    Obaidat, Ihab M.; Issa, Bashar; Haik, Yousef

    2015-01-01

    Localized magnetic hyperthermia using magnetic nanoparticles (MNPs) under the application of small magnetic fields is a promising tool for treating small or deep-seated tumors. For this method to be applicable, the amount of MNPs used should be minimized. Hence, it is essential to enhance the power dissipation or heating efficiency of MNPs. Several factors influence the heating efficiency of MNPs, such as the amplitude and frequency of the applied magnetic field and the structural and magnetic properties of MNPs. We discuss some of the physics principles for effective heating of MNPs focusing on the role of surface anisotropy, interface exchange anisotropy and dipolar interactions. Basic magnetic properties of MNPs such as their superparamagnetic behavior, are briefly reviewed. The influence of temperature on anisotropy and magnetization of MNPs is discussed. Recent development in self-regulated hyperthermia is briefly discussed. Some physical and practical limitations of using MNPs in magnetic hyperthermia are also briefly discussed. PMID:28347000

  12. Triggered self-assembly of magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Ye, L.; Pearson, T.; Cordeau, Y.; Mefford, O. T.; Crawford, T. M.

    2016-03-01

    Colloidal magnetic nanoparticles are candidates for application in biology, medicine and nanomanufac-turing. Understanding how these particles interact collectively in fluids, especially how they assemble and aggregate under external magnetic fields, is critical for high quality, safe, and reliable deployment of these particles. Here, by applying magnetic forces that vary strongly over the same length scale as the colloidal stabilizing force and then varying this colloidal repulsion, we can trigger self-assembly of these nanoparticles into parallel line patterns on the surface of a disk drive medium. Localized within nanometers of the medium surface, this effect is strongly dependent on the ionic properties of the colloidal fluid but at a level too small to cause bulk colloidal aggregation. We use real-time optical diffraction to monitor the dynamics of self-assembly, detecting local colloidal changes with greatly enhanced sensitivity compared with conventional light scattering. Simulations predict the triggering but not the dynamics, especially at short measurement times. Beyond using spatially-varying magnetic forces to balance interactions and drive assembly in magnetic nanoparticles, future measurements leveraging the sensitivity of this approach could identify novel colloidal effects that impact real-world applications of these nanoparticles.

  13. Triggered self-assembly of magnetic nanoparticles

    PubMed Central

    Ye, L.; Pearson, T.; Cordeau, Y.; Mefford, O. T.; Crawford, T. M.

    2016-01-01

    Colloidal magnetic nanoparticles are candidates for application in biology, medicine and nanomanufac-turing. Understanding how these particles interact collectively in fluids, especially how they assemble and aggregate under external magnetic fields, is critical for high quality, safe, and reliable deployment of these particles. Here, by applying magnetic forces that vary strongly over the same length scale as the colloidal stabilizing force and then varying this colloidal repulsion, we can trigger self-assembly of these nanoparticles into parallel line patterns on the surface of a disk drive medium. Localized within nanometers of the medium surface, this effect is strongly dependent on the ionic properties of the colloidal fluid but at a level too small to cause bulk colloidal aggregation. We use real-time optical diffraction to monitor the dynamics of self-assembly, detecting local colloidal changes with greatly enhanced sensitivity compared with conventional light scattering. Simulations predict the triggering but not the dynamics, especially at short measurement times. Beyond using spatially-varying magnetic forces to balance interactions and drive assembly in magnetic nanoparticles, future measurements leveraging the sensitivity of this approach could identify novel colloidal effects that impact real-world applications of these nanoparticles. PMID:26975332

  14. Triggered self-assembly of magnetic nanoparticles.

    PubMed

    Ye, L; Pearson, T; Cordeau, Y; Mefford, O T; Crawford, T M

    2016-03-15

    Colloidal magnetic nanoparticles are candidates for application in biology, medicine and nanomanufacturing. Understanding how these particles interact collectively in fluids, especially how they assemble and aggregate under external magnetic fields, is critical for high quality, safe, and reliable deployment of these particles. Here, by applying magnetic forces that vary strongly over the same length scale as the colloidal stabilizing force and then varying this colloidal repulsion, we can trigger self-assembly of these nanoparticles into parallel line patterns on the surface of a disk drive medium. Localized within nanometers of the medium surface, this effect is strongly dependent on the ionic properties of the colloidal fluid but at a level too small to cause bulk colloidal aggregation. We use real-time optical diffraction to monitor the dynamics of self-assembly, detecting local colloidal changes with greatly enhanced sensitivity compared with conventional light scattering. Simulations predict the triggering but not the dynamics, especially at short measurement times. Beyond using spatially-varying magnetic forces to balance interactions and drive assembly in magnetic nanoparticles, future measurements leveraging the sensitivity of this approach could identify novel colloidal effects that impact real-world applications of these nanoparticles.

  15. Nonlinear energy dissipation of magnetic nanoparticles in oscillating magnetic fields

    NASA Astrophysics Data System (ADS)

    Soto-Aquino, D.; Rinaldi, C.

    2015-11-01

    The heating of magnetic nanoparticle suspensions subjected to alternating magnetic fields enables a variety of emerging applications such as magnetic fluid hyperthermia and triggered drug release. Rosensweig (2002) [25] obtained a model for the heat dissipation rate of a collection of non-interacting particles. However, the assumptions made in this analysis make it rigorously valid only in the limit of small applied magnetic field amplitude and frequency (i.e., values of the Langevin parameter that are much less than unity and frequencies below the inverse relaxation time). In this contribution we approach the problem from an alternative point of view by solving the phenomenological magnetization relaxation equation exactly for the case of arbitrary magnetic field amplitude and frequency and by solving a more accurate magnetization relaxation equation numerically. We also use rotational Brownian dynamics simulations of non-interacting magnetic nanoparticles subjected to an alternating magnetic field to estimate the rate of energy dissipation and compare the results of the phenomenological theories to the particle-scale simulations. The results are summarized in terms of a normalized energy dissipation rate and show that Rosensweig's expression provides an upper bound on the energy dissipation rate achieved at high field frequency and amplitude. Estimates of the predicted dependence of energy dissipation rate, quantified as specific absorption rate (SAR), on magnetic field amplitude and frequency, and particle core and hydrodynamic diameter, are also given.

  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

  17. Targeted polymeric magnetic nanoparticles for brain imaging

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

  18. Thermal-driven attachment of gold nanoparticles prepared with ascorbic acid onto indium tin oxide surfaces

    NASA Astrophysics Data System (ADS)

    Aziz, Md. Abdul; Oyama, Munetaka

    2013-05-01

    Thermal-driven attachment of gold nanoparticles (AuNPs), of which size was less than 50 nm, onto the surfaces of indium tin oxide (ITO) is reported as a new phenomenon. This was permitted by preparing AuNPs via the reduction of hydrogen tetrachloroaurate (HAuCl4) with ascorbic acid (AA). While the AuNPs prepared via the AA reduction sparsely attached on the surface of ITO even at room temperature, a heat-up treatment at ca. 75 °C caused denser attachment of AuNPs on ITO surfaces. The attached density and the homogeneity after the thermal treatment were better than those of AuNP/ITO prepared using 3-aminopropyl-trimethoxysilane linker molecules. The denser attachment was observed similarly both by the immersion of ITO samples after the preparations of AuNPs by AA and by the in situ preparation of AuNPs with AA together with ITO samples. Thus, it is considered that the thermal-driven attachment of AuNPs would occur after the formation of AuNPs in the aqueous solutions, not via the growth of AuNPs on ITO surfaces. The preparation of AuNPs with AA would be a key for the thermal-driven attachment because the same attachments were not observed for AuNPs prepared with citrate ions or commercially available tannic acid-capped AuNPs.

  19. Nanocomposites of magnetic cobalt nanoparticles and cellulose

    NASA Astrophysics Data System (ADS)

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

    2008-10-01

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

  20. Galvanic corrosion between dental precious alloys and magnetic stainless steels used for dental magnetic attachments.

    PubMed

    Takahashi, Noriko; Takada, Yukyo; Okuno, Osamu

    2008-03-01

    In this study, we examined the corrosion behavior of dental precious alloys and magnetic stainless steels, namely SUS 444, SUS XM27, and SUS 447J1, used for dental magnetic attachments. Their galvanic corrosion behavior was evaluated from the viewpoint of corrosion potentials when they were in contact with each other. Rest potentials of the precious alloys were constantly higher than those of magnetic stainless steels. Since most gold alloys raised the corrosion potential more significantly than silver alloys did, silver alloys seemed to be better suited than gold alloys for combination with magnetic stainless steels. However, all corrosion potential values were sufficiently lower than the breakdown potentials of the stainless steels and existed within their passive regions. Based on the findings of this study, SUS XM27 and SUS 447J1--which exhibited higher breakdown potentials than SUS 444--emerged as the preferred choices for combination with gold alloys.

  1. Targeted diagnostic magnetic nanoparticles for medical imaging of pancreatic cancer.

    PubMed

    Rosenberger, I; Strauss, A; Dobiasch, S; Weis, C; Szanyi, S; Gil-Iceta, L; Alonso, E; González Esparza, M; Gómez-Vallejo, V; Szczupak, B; Plaza-García, S; Mirzaei, S; Israel, L L; Bianchessi, S; Scanziani, E; Lellouche, J-P; Knoll, P; Werner, J; Felix, K; Grenacher, L; Reese, T; Kreuter, J; Jiménez-González, M

    2015-09-28

    Highly aggressive cancer types such as pancreatic cancer possess a mortality rate of up to 80% within the first 6months after diagnosis. To reduce this high mortality rate, more sensitive diagnostic tools allowing an early stage medical imaging of even very small tumours are needed. For this purpose, magnetic, biodegradable nanoparticles prepared using recombinant human serum albumin (rHSA) and incorporated iron oxide (maghemite, γ-Fe2O3) nanoparticles were developed. Galectin-1 has been chosen as target receptor as this protein is upregulated in pancreatic cancer and its precursor lesions but not in healthy pancreatic tissue nor in pancreatitis. Tissue plasminogen activator derived peptides (t-PA-ligands), that have a high affinity to galectin-1 have been chosen as target moieties and were covalently attached onto the nanoparticle surface. Improved targeting and imaging properties were shown in mice using single photon emission computed tomography-computer tomography (SPECT-CT), a handheld gamma camera, and magnetic resonance imaging (MRI).

  2. Magnetic properties of Ni and Cu-Ni nanoparticles

    NASA Astrophysics Data System (ADS)

    Ganga, B. G.; Santhosh, P. N.; Thomas, P. John

    2012-06-01

    Ni and Cu-Ni nanoparticles were prepared by solution phase method and crystal phase was identified by XRD. SEM and EDX were used to analyze morphology and elemental composition of nanoparticles. Magnetic measurements indicate that Ni nanoparticles are superparamagnetic at room temperature and blocking temperature is around 103 K. Ferromagnetism is observed in the case of Cu-Ni nanoparticles with decrease in magnetization compared to Ni nanoparticles.

  3. Electrochemical analysis of gold-coated magnetic nanoparticles for detecting immunological interaction

    NASA Astrophysics Data System (ADS)

    Pham, Thao Thi-Hien; Sim, Sang Jun

    2010-01-01

    An electrochemical impedance immunosensor was developed for detecting the immunological interaction between human immunoglobulin (IgG) and protein A from Staphylococcus aureus based on the immobilization of human IgG on the surface of modified gold-coated magnetic nanoparticles. The nanoparticles with an Au shell and Fe oxide cores were functionalized by a self-assembled monolayer of 11-mercaptoundecanoic acid. The electrochemical analysis was conducted on the modified magnetic carbon paste electrodes with the nanoparticles. The magnetic nanoparticles were attached to the surface of the magnetic carbon paste electrodes via magnetic force. The cyclic voltammetry technique and electrochemical impedance spectroscopy measurements of the magnetic carbon paste electrodes coated with magnetic nanoparticles-human IgG complex showed changes in its alternating current (AC) response both after the modification of the surface of the electrode and the addition of protein A. The immunological interaction between human IgG on the surface of the modified magnetic carbon paste electrodes and protein A in the solution could be successfully monitored.

  4. Understanding the Role of Solvation Forces on the Preferential Attachment of Nanoparticles in Liquid

    DOE PAGES

    Welch, David A.; Woehl, Taylor J.; Park, Chiwoo; ...

    2015-11-20

    We discuss optimization of colloidal nanoparticle synthesis techniques, which requires an understanding of underlying particle growth mechanisms. Nonclassical growth mechanisms are particularly important as they affect nanoparticle size and shape distributions, which in turn influence functional properties. For example, preferential attachment of nanoparticles is known to lead to the formation of mesocrystals, although the formation mechanism is currently not well-understood. Here we employ in situ liquid cell scanning transmission electron microscopy and steered molecular dynamics (SMD) simulations to demonstrate that the experimentally observed preference for end-to-end attachment of silver nanorods is a result of weaker solvation forces occurring at rodmore » ends. In conclusion, SMD reveals that when the side of a nanorod approaches another rod, perturbation in the surface-bound water at the nanorod surface creates significant energy barriers to attachment. Additionally, rod morphology (i.e., facet shape) effects can explain the majority of the side attachment effects that are observed experimentally.« less

  5. Synthesis and magnetic properties of nickel nanoparticles

    NASA Astrophysics Data System (ADS)

    Singh, Jaiveer; Patel, Tarachand; Kaurav, Netram; Okram, Gunadhor S.

    2016-05-01

    Monodisperse nickel nanoparticles (Ni-NPs) were synthesized via a thermal decomposition process. The NPs were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). They were spherical with mean diameter of 4 nm. Zero field cooled (ZFC) and field cooled (FC) magnetization versus temperature data displayed interesting magnetic interactions. ZFC showed a peak at 4.49 K, indicating the super paramagnetic behavior. Magnetic anisotropic constant was estimated to be 4.62×105 erg/cm3 and coercive field was 168 Oe at 3 K.

  6. Nonlinear simulations to optimize magnetic nanoparticle hyperthermia

    SciTech Connect

    Reeves, Daniel B. Weaver, John B.

    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.

  7. Simultaneous quantification of multiple magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

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

  8. Measuring and controlling the transport of magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Stephens, Jason R.

    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

  9. Chitosan magnetic nanoparticles for drug delivery systems.

    PubMed

    Assa, Farnaz; Jafarizadeh-Malmiri, Hoda; Ajamein, Hossein; Vaghari, Hamideh; Anarjan, Navideh; Ahmadi, Omid; Berenjian, Aydin

    2016-06-01

    The potential of magnetic nanoparticles (MNPs) in drug delivery systems (DDSs) is mainly related to its magnetic core and surface coating. These coatings can eliminate or minimize their aggregation under physiological conditions. Also, they can provide functional groups for bioconjugation to anticancer drugs and/or targeted ligands. Chitosan, as a derivative of chitin, is an attractive natural biopolymer from renewable resources with the presence of reactive amino and hydroxyl functional groups in its structure. Chitosan nanoparticles (NPs), due to their huge surface to volume ratio as compared to the chitosan in its bulk form, have outstanding physico-chemical, antimicrobial and biological properties. These unique properties make chitosan NPs a promising biopolymer for the application of DDSs. In this review, the current state and challenges for the application magnetic chitosan NPs in drug delivery systems were investigated. The present review also revisits the limitations and commercial impediments to provide insight for future works.

  10. Tracking stem cells using magnetic nanoparticles

    PubMed Central

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

    2011-01-01

    Stem cell therapies offer great promise for many diseases, especially those without current effective treatments. It is believed that noninvasive imaging techniques, which offer the ability to track the status of cells after transplantation, will expedite progress in this field and help to achieve maximized therapeutic effect. Today’s biomedical imaging technology allows for real-time, noninvasive monitoring of grafted stem cells including their biodistribution, migration, survival, and differentiation, with magnetic resonance imaging (MRI) of nanoparticle-labeled cells being one of the most commonly used techniques. Among the advantages of MR cell tracking are its high spatial resolution, no exposure to ionizing radiation, and clinical applicability. In order to track cells by MRI, the cells need to be labeled with magnetic nanoparticles, for which many types exist. There are several cellular labeling techniques available, including simple incubation, use of transfection agents, magnetoelectroporation, and magnetosonoporation. In this overview article, we will review the use of different magnetic nanoparticles and discuss how these particles can be used to track the distribution of transplanted cells in different organ systems. Caveats and limitations inherent to the tracking of nanoparticle-labeled stem cells are also discussed. PMID:21472999

  11. Boosting oncolytic adenovirus potency with magnetic nanoparticles and magnetic force.

    PubMed

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

    2010-08-02

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

  12. Cross-linked magnetic nanoparticles from poly(ethylene glycol) and dodecyl grafted poly(succinimide) as magnetic resonance probes.

    PubMed

    Yang, Hee-Man; Park, Chan Woo; Lim, Sujin; Park, Sung-Il; Chung, Bong Hyun; Kim, Jong-Duk

    2011-12-14

    Cross-linked magnetic nanoparticles were developed to improve the structural stability of amphiphilic polymer coated magnetic nanoparticles. These nanoparticles show strong potential for biomedical applications such as magnetic resonance imaging (MRI).

  13. Mercury-based cobalt magnetic fluids and cobalt nanoparticles

    NASA Astrophysics Data System (ADS)

    Massart, R.; Rasolonjatovo, B.; Neveu, S.; Cabuil, V.

    2007-01-01

    This paper describes the synthesis of a magnetic and conducting liquid consisting of cobalt nanoparticles dispersed in mercury. The magnetic nanoparticles are obtained in one step by the electroreduction of a cobalt(II) solution on mercury. These particles are then extracted using an organic solution of surfactant in order to obtain a ferrofluid based on cobalt nanoparticles.

  14. Grafting single molecule magnets on gold nanoparticles.

    PubMed

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

    2014-01-29

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

  15. Bio-inspired photoresponse of porphyrin-attached gold nanoparticles on a field-effect transistor.

    PubMed

    Miyachi, Mariko; Yamanoi, Yoshinori; Nakazato, Kazuo; Nishihara, Hiroshi

    2014-09-01

    A bio-inspired photoresponse was engineered in porphyrin-attached Au nanoparticles (AuNPs) on a field-effect transistor (FET). The system mimics photosynthetic electron transfer, using porphyrin derivatives as photosensitizers and AuNPs as photoelectron counting devices. Porphyrin-protected AuNPs were immobilized onto the gate of an FET via the formation of self-assembled monolayers. Photoinduced electron transfer from the porphyrin led to single electron transfer at the Au nanoparticles, which was monitored via a changing gate voltage on the FET in the presence of organic electrolyte. The further attachment of other functional molecules to this system should enable various other potential functionalities. This article is part of a special issue entitled: photosynthesis research for sustainability: keys to produce clean energy.

  16. Oriented attachment kinetics for ligand capped nanocrystals: coarsening of thiol-PbS nanoparticles.

    PubMed

    Zhang, Jing; Wang, Yonghao; Zheng, Jinsheng; Huang, Feng; Chen, Dagui; Lan, Youzhao; Ren, Guoqiang; Lin, Zhang; Wang, Chen

    2007-02-15

    In this work, the growth kinetics of thiol-capped PbS nanoparticles was studied. Two-stage growth process was observed, which was controlled first by oriented attachment (OA) mechanism and then by the hybrid Ostwald ripening (OR) and OA mechanism. Different from the NaOH-ZnS system, where OA will occur between any two multilevel nanoparticles, an OA kinetic model only considering the attachment related to original particles was fitted well with the experimental results. Analysis reveals that this model may be a universal one to describe the OA crystal growth process of nanocrystals capped with easily destroyed ligands, such as thiol-ZnS in the previous report. The OA crystal growth characteristics determined by the surface agent were discussed and compared. We propose that with stronger surface capping, the OR growth of nanocrystals is hindered, which facilitates the size controlling via OA kinetics during nanosynthesis.

  17. Fabrication of ordered metallic and magnetic heterostructured DNA-Nanoparticle hybrids.

    PubMed

    Kinsella, Joseph M; Ivanisevic, Albena

    2008-06-01

    Here we provide a method based on enzymatically catalyzed reactions to cleave and ligate DNA molecules coated with nanoparticles to fabricate multi-component structures. This is done by simultaneously digesting two solutions of nanoparticle coated DNA, one with iron oxide particles the other gold particles, which yields short DNA fragments with complementary single stranded overhangs. When added together and re-attached using ligase enzymes multi-component nanoparticle coated structures are formed providing a novel method to fabricate complicated nanoparticle arrangements from the bottom up. We evaluated the fabrication by characterizing the samples with gel electrophoresis and magnetic force microscopy (MFM). The electrophoresis provides proof that the coated DNA molecules were digested with restriction enzymes and ligated by the T4 ligase enzymes. MFM experiments allow us to visualize the multi-component strands and analyze the magnetic versus metallic segments.

  18. Protein detection with magnetic nanoparticles in a rotating magnetic field

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  19. In situ TEM investigations of mineral growth through oriented attachment of nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, D.; Nielsen, M.; Lee, J. R.; Frandsen, C.; Banfield, J. F.; Kisailus, D.; De Yoreo, J.

    2012-12-01

    The growth of crystals through aggregation and coalescence of nanoparticles is now recognized as a widespread phenomenon in biomineral, biomimetic and natural systems, and during synthetic production of nanoparticles and nanowires. The resulting crystals often exhibit complex forms ranging from quasi-one-dimensional chains to 3D hierarchical and self-similar superstructures. Yet the final structure typically diffracts as a single crystal, implying that the primary particles aligned during growth. When coalignment is accompanied by coalescence, this growth process is often referred to as oriented attachment (OA). OA is now recognized as an important mechanism of crystal growth in many materials in the environment. However, the pathway by which OA occurs has not been established. Although the preservation of primary particle morphology and formation of twins and stacking faults at particle-particle boundaries strongly suggest a sequence of whole particle alignment followed by interface elimination, atom-by-atom reorientation via dislocation and grain-boundary migration after attachment are another potential mechanism. If indeed the primary particles align before attachment, the dynamics of that process and the forces that drive it have yet to be revealed. To achieve this understanding we are investigating crystal nucleation and oriented attachment in a number of systems, such as iron oxides and oxyhydroxide as well as titanium dioxide, through in situ and ex situ TEM. We performed high-resolution TEM using a fluid cell to directly observe oriented attachment of iron oxyhydroxide nanoparticles. The particles undergo continuous rotation and interaction until they find a perfect lattice match. A sudden jump to contact then occurs over less than 1 nanometer, followed by lateral atom-by-atom addition initiated at the contact point. Interface elimination proceeds at a rate consistent with the curvature dependence of the Gibbs free energy. Measured translational and

  20. DLVO Approximation Methods for Predicting the Attachment of Silver Nanoparticles to Ceramic Membranes.

    PubMed

    Mikelonis, Anne M; Youn, Sungmin; Lawler, Desmond F

    2016-02-23

    This article examines the influence of three common stabilizing agents (citrate, poly(vinylpyrrolidone) (PVP), and branched poly(ethylenimine) (BPEI)) on the attachment affinity of silver nanoparticles to ceramic water filters. Citrate-stabilized silver nanoparticles were found to have the highest attachment affinity (under conditions in which the surface potential was of opposite sign to the filter). This work demonstrates that the interaction between the electrical double layers plays a critical role in the attachment of nanoparticles to flat surfaces and, in particular, that predictions of double-layer interactions are sensitive to boundary condition assumptions (constant charge vs constant potential). The experimental deposition results can be explained when using different boundary condition assumptions for different stabilizing molecules but not when the same assumption was assumed for all three types of particles. The integration of steric interactions can also explain the experimental deposition results. Particle size was demonstrated to have an effect on the predicted deposition for BPEI-stabilized particles but not for PVP.

  1. Magnetic properties of nanocomposites formed by magnetic nanoparticles embedded in a non-magnetic matrix: a simulation approach.

    PubMed

    Serna, J Ceballos; Restrepo-Parra, E; Rojas, J C Riaño

    2012-06-01

    In this work, simulations of magnetic properties of nanocomposites formed by magnetic nanoparticles embedded in a non magnetic matrix are presented. These simulations were carried by means of the Monte Carlo Method and Heisenberg model. Properties as magnetization and Hysteresis loops were obtained varying different parameters as the nanoparticle size, distance between nanoparticles and temperature. The model employed includes interaction between ions belonging to each nanoparticle and also the interaction between nanoparticles. Results show that the magnetization and the coercive force decrease as a function of the nanoparticles distance.

  2. Magnetic nanoparticles as gene delivery agents: enhanced transfection in the presence of oscillating magnet arrays

    NASA Astrophysics Data System (ADS)

    McBain, S. C.; Griesenbach, U.; Xenariou, S.; Keramane, A.; Batich, C. D.; Alton, E. W. F. W.; Dobson, J.

    2008-10-01

    Magnetic nanoparticle-based gene transfection has been shown to be effective in combination with both viral vectors and with non-viral agents. In these systems, therapeutic or reporter genes are attached to magnetic nanoparticles which are then focused to the target site/cells via high-field/high-gradient magnets. The technique has been shown to be efficient and rapid for in vitro transfection and compares well with cationic lipid-based reagents, producing good overall transfection levels with lower doses and shorter transfection times. In spite of its potential advantages (particularly for in vivo targeting), the overall transfection levels do not generally exceed those of other non-viral agents. In order to improve the overall transfection levels while maintaining the advantages inherent in this technique, we have developed a novel, oscillating magnet array system which adds lateral motion to the particle/gene complex in order to promote transfection. Experimental results indicate that the system significantly enhances overall in vitro transfection levels in human airway epithelial cells compared to both static field techniques (p<0.005) and the cationic lipids (p<0.001) tested. In addition, it has the previously demonstrated advantages of magnetofection—rapid transfection times and requiring lower levels of DNA than cationic lipid-based transfection agents. This method shows potential for non-viral gene delivery both in vitro and in vivo.

  3. 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

  4. Mechanistic Insights to the Influence of Adsorbed Organic Macromolecules on Nanoparticle Attachment Efficiency in Porous Media

    NASA Astrophysics Data System (ADS)

    Phenrat, T.; Song, J.; Cisneros, C. M.; Schoenfelder, D. P.; Illangasekare, T. H.; Tilton, R. D.; Lowry, G. V.

    2009-12-01

    Assessing the potential risks of natural or engineered nanoparticles to the environment and human health requires the ability to predict their mobility in porous media such as groundwater aquifers or sand filters used in water treatment. Semi-empirical correlations to predict the collision efficiency of electrostatically stabilized nanoparticles are available; however, they are not applicable to nanoparticles coated with natural organic matter (NOM) or polymeric surface coatings because the existing correlations do not account the electrosteric repulsions and lubrication afforded by coatings that inhibit or reverse nanoparticle attachment to surfaces. Regression analysis of published data on the collision efficiency of NOM-coated latex and hematite particles, and on new data collected for poly(styrene sulfonate)-, carboxy methyl cellulose, and polyaspartate-coated hematite and titanium dioxide nanoparticles was used to develop an empirical correlation of the collision efficiency of NOM- and polymer-coated nanomaterials and dimensionless parameters including the adsorbed layer-electrokinetic parameter (NLEK) representing electrosteric repulsions and lubrication afforded by adsorbed NOM or polyelectrolyte. An empirical correlation with three dimensionless parameters can predict the measured collision efficiency on coated metal oxide nanoparticles over a wide dynamic range in particle type, coating type, and solution conditions (~80 data points). This study indicates that including the adsorbed NOM and polymer layer properties of the properties is essential for understanding the transport and fate of NOM- and polymer-coated natural and manufactured nanomaterials in porous media.

  5. Biomedical tools based on magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  6. Reorientation Response of Magnetic Microspheres Attached to Gold Electrodes Under an Applied Magnetic Field

    NASA Astrophysics Data System (ADS)

    De Los Santos Valladares, L.; Dominguez, A. Bustamante; Aguiar, J. Albino; Reeve, R. M.; Mitrelias, T.; Langford, R. M.; Azuma, Y.; Barnes, C. H. W.; Majima, Y.

    2013-08-01

    In this work, we report the mechanical reorientation of thiolated ferromagnetic microspheres bridging a pair of gold electrodes under an external magnetic field. When an external magnetic field (7 kG) is applied during the measurement of the current-voltage characteristics of a carboxyl ferromagnetic microsphere (4 μm diameter) attached to two gold electrodes by self-assembled monolayers (SAMs) of octane dithiol (C8H18S2), the current signal is distorted. Rather than due to magnetoresistance, this effect is caused by a mechanical reorientation of the ferromagnetic sphere, which alters the number of SAMs between the sphere and the electrodes and therefore affects conduction. To study the physical reorientation of the ferromagnetic particles, we measure their hysteresis loops while suspended in a liquid solution.

  7. Acute and subchronic toxicity analysis of surface modified paclitaxel attached hydroxyapatite and titanium dioxide nanoparticles.

    PubMed

    Venkatasubbu, Gopinath Devanand; Ramasamy, S; Gaddam, Pramod Reddy; Kumar, J

    2015-01-01

    Nanoparticles are widely used for targeted drug delivery applications. Surface modification with appropriate polymer and ligands is carried out to target the drug to the affected area. Toxicity analysis is carried out to evaluate the safety of the surface modified nanoparticles. In this study, paclitaxel attached, folic acid functionalized, polyethylene glycol modified hydroxyapatite and titanium dioxide nanoparticles were used for targeted drug delivery system. The toxicological behavior of the system was studied in vivo in rats and mice. Acute and subchronic studies were carried out. Biochemical, hematological, and histopathological analysis was also done. There were no significant alterations in the biochemical parameters at a low dosage. There was a small change in alkaline phosphatase (ALP) level at a high dosage. The results indicate a safe toxicological profile.

  8. Functionalized magnetic nanoparticles for biomedical applications.

    PubMed

    Gudovan, Dragoș; Balaure, Paul Cătălin; Mihăiescu, Dan Eduard; Fudulu, Adrian; Purcăreanu, Bogdan; Radu, Mihai

    2015-01-01

    Functionalized magnetic nanoparticles followed two main directions in the field of biomedical applications: one direction is as image enhancing agents for magnetic resonance imaging (MRI) and the other is as drugdelivery devices for various biologically-active substances. A third field which just emerges in nanomedicine is the field of the so-called theranostic devices which combines in the same delivery vehicle both the therapeutic agent and the contrast substance. The advantages of using nanoparticles instead of larger carriers for delivery of both drug and image contrast enhancing agents will be highlighted throughout this review article. Despite the ever increasing number of articles reporting both in vitro and in vivo studies carried out on functionalized magnetic nanoparticles and envisaging their potential biomedical applications, only few formulations reached the phase of clinical trials and even fewer became marketed products. The perspectives in the field are open, since new drugs require new delivery devices and possibly new means of functionalization. At the same time, the field of nanomedicine also provides the opportunity to better exploit drugs that are already in clinical use by improving their bioavailability through appropriate nanoformulations.

  9. Phosphonate-anchored monolayers for antibody binding to magnetic nanoparticles.

    PubMed

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

    2011-10-04

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

  10. Fabrication of an Implant-Supported Orbital Prosthesis with Bar-Magnetic Attachment: A Clinical Report

    PubMed Central

    Aalaei, Shima; Abolhassani, Abolhassan; Nematollahi, Fatemeh; Beyabanaki, Elaheh; Mangoli, Amir Ali

    2015-01-01

    Implant-supported craniofacial prostheses are made to restore defective areas in the face and cranium. This clinical report describes a technique for fabrication of an orbital prosthesis with three adjacent implants in the left lateral orbital rim of a 60-year-old woman. Selection of appropriate attachment system (individual magnetic abutments versus bar-clip attachment) for implant-supported orbital prostheses depends upon the position of implants. Bar-magnetic attachment has been selected as the retention mechanism in the present case. PMID:27559354

  11. Fabrication of an Implant-Supported Orbital Prosthesis with Bar-Magnetic Attachment: A Clinical Report.

    PubMed

    Aalaei, Shima; Abolhassani, Abolhassan; Nematollahi, Fatemeh; Beyabanaki, Elaheh; Mangoli, Amir Ali

    2015-12-01

    Implant-supported craniofacial prostheses are made to restore defective areas in the face and cranium. This clinical report describes a technique for fabrication of an orbital prosthesis with three adjacent implants in the left lateral orbital rim of a 60-year-old woman. Selection of appropriate attachment system (individual magnetic abutments versus bar-clip attachment) for implant-supported orbital prostheses depends upon the position of implants. Bar-magnetic attachment has been selected as the retention mechanism in the present case.

  12. Thermoinduced magnetic moment in akaganéite nanoparticles

    NASA Astrophysics Data System (ADS)

    Urtizberea, A.; Luis, F.; Millán, A.; Natividad, E.; Palacio, F.; Kampert, E.; Zeitler, U.

    2011-06-01

    It is shown that akaganéite β-FeOOH provides a good model material to experimentally investigate thermoinduced magnetic moments in antiferromagnetic nanoparticles. We characterize the magnetic properties, exchange field, anisotropy field, and antiferromagnetic susceptibility of bulk akaganéite. In the nanoparticles, we find a drastic enhancement of the antiferromagnetic susceptibility, a phenomenon first predicted by Néel. Also, we find that akaganéite nanoparticles possess a thermoinduced magnetic moment.

  13. Magnetic behavior of biosynthesized Co3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Diallo, A.; Doyle, T. B.; Mothudi, B. M.; Manikandan, E.; Rajendran, V.; Maaza, M.

    2017-02-01

    This contribution reports for the 1st time on the magnetic behavior of CO3O4 nanoparticles synthesized by a "green" process using an Aspalathus linearis' leaves natural extract. More accurately magnetic behavior of CO3O4 nanoparticles successfully biosynthesized was investigated using vibrating sample magnetometer. The magnetization behavior for the samples manifests a combination of size dependent antiferromagnetic and paramagnetic behaviors, respectively, for the core and shell of the nanoparticles.

  14. Magnetic nanoparticle-based drug delivery for cancer therapy.

    PubMed

    Tietze, Rainer; Zaloga, Jan; Unterweger, Harald; Lyer, Stefan; Friedrich, Ralf P; Janko, Christina; Pöttler, Marina; Dürr, Stephan; Alexiou, Christoph

    2015-12-18

    Nanoparticles have belonged to various fields of biomedical research for quite some time. A promising site-directed application in the field of nanomedicine is drug targeting using magnetic nanoparticles which are directed at the target tissue by means of an external magnetic field. Materials most commonly used for magnetic drug delivery contain metal or metal oxide nanoparticles, such as superparamagnetic iron oxide nanoparticles (SPIONs). SPIONs consist of an iron oxide core, often coated with organic materials such as fatty acids, polysaccharides or polymers to improve colloidal stability and to prevent separation into particles and carrier medium [1]. In general, magnetite and maghemite particles are those most commonly used in medicine and are, as a rule, well-tolerated. The magnetic properties of SPIONs allow the remote control of their accumulation by means of an external magnetic field. Conjugation of SPIONs with drugs, in combination with an external magnetic field to target the nanoparticles (so-called "magnetic drug targeting", MDT), has additionally emerged as a promising strategy of drug delivery. Magnetic nanoparticle-based drug delivery is a sophisticated overall concept and a multitude of magnetic delivery vehicles have been developed. Targeting mechanism-exploiting, tumor-specific attributes are becoming more and more sophisticated. The same is true for controlled-release strategies for the diseased site. As it is nearly impossible to record every magnetic nanoparticle system developed so far, this review summarizes interesting approaches which have recently emerged in the field of targeted drug delivery for cancer therapy based on magnetic nanoparticles.

  15. Modular Fabrication of Polymer Brush Coated Magnetic Nanoparticles: Engineering the Interface for Targeted Cellular Imaging.

    PubMed

    Oz, Yavuz; Arslan, Mehmet; Gevrek, Tugce N; Sanyal, Rana; Sanyal, Amitav

    2016-08-03

    Development of efficient and rapid protocols for diversification of functional magnetic nanoparticles (MNPs) would enable identification of promising candidates using high-throughput protocols for applications such as diagnostics and cure through early detection and localized delivery. Polymer brush coated magnetic nanoparticles find use in many such applications. A protocol that allows modular diversification of a pool of parent polymer coated nanoparticles will lead to a library of functional materials with improved uniformity. In the present study, polymer brush coated parent magnetic nanoparticles obtained using reversible addition-fragmentation chain transfer (RAFT) polymerization are modified to obtain nanoparticles with different "clickable" groups. In this design, trithiocarbonate group terminated polymer brushes are "grafted from" MNPs using a catechol group bearing initiator. A postpolymerization radical exchange reaction allows installation of "clickable" functional groups like azides and maleimides on the chain ends of the polymers. Thus, modified MNPs can be functionalized using alkyne-containing and thiol-containing moieties like peptides and dyes using the alkyne-azide cycloaddition and the thiol-ene conjugation, respectively. Using the approach outlined here, a cell surface receptor targeting cyclic peptide and a fluorescent dye are attached onto nanoparticle surface. This multifunctional construct allows selective recognition of cancer cells that overexpress integrin receptors. Furthermore, the approach outlined here is not limited to the installation of azide and maleimide functional groups but can be expanded to a variety of "clickable" groups to allow nanoparticle modification using a broad range of chemical conjugations.

  16. 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 μg of streptavidin, 128 μg of PAPP-A, and 125 μg 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.

  17. Drug embedded PVP coated magnetic nanoparticles for targeted killing of breast cancer cells.

    PubMed

    Rose, P Arsula; Praseetha, P K; Bhagat, Madhulika; Alexander, Princy; Abdeen, Sunitha; Chavali, Murthy

    2013-10-01

    Magnetic drug targeting is a drug delivery system that can be used in loco-regional cancer treatment. Coated magnetic particles, called carriers, are very useful for delivering chemotherapeutic drugs. Magnetic carriers were synthesized by co-precipitation of iron oxide followed by coating with polyvinyl pyrrolidone (PVP). Characterization was performed using X-ray diffraction, TEM, TGA, FTIR and UV-Vis Spectroscopy. Magnetite (Fe3O4) remained as the core of the carrier. The amount of PVP bound to the iron oxide nanoparticles was estimated by thermogravimetric analysis (TGA) and the attachment of PVP to the iron oxide nanoparticles confirmed by FTIR analysis. The loading efficiency of Epirubicin hydrochloride onto the PVP coated and uncoated iron oxide nanoparticles was measured at intervals such as 1 hr and 24 hrs by UV-Vis Spectroscopy. The binding of Epirubicin hydrochloride to the PVP coated and uncoated iron oxide nanoparticles were confirmed by FTIR analysis. The present findings showed that Epirubicin hydrochloride loaded PVP coated iron oxide nanoparticles are promising for magnetically targeted drug delivery. The drug displayed increased cell cytotoxicity at lower concentrations when conjugated with the nanoparticles than being administered conventionally as individual drugs.

  18. Magnetic nanoparticles: essential factors for sustainable environmental applications.

    PubMed

    Tang, Samuel C N; Lo, Irene M C

    2013-05-15

    In recent years, there has been an increasing use of engineered magnetic nanoparticles for remediation and water treatments, leading to elevated public concerns. To this end, it is necessary to enhance the understanding of how these magnetic nanoparticles react with contaminants and interact with the surrounding environment during applications. This review aims to provide a holistic overview of current knowledge of magnetic nanoparticles in environmental applications, emphasizing studies of zero-valent iron (nZVI), magnetite (Fe3O4) and maghemite (γ-Fe2O3) nanoparticles. Contaminant removal mechanisms by magnetic nanoparticles are presented, along with factors affecting the ability of contaminant desorption. Factors influencing the recovery of magnetic nanoparticles are outlined, describing the challenges of magnetic particle collection. The aggregation of magnetic nanoparticles is described, and methods for enhancing stability are summarized. Moreover, the toxicological effects owing to magnetic nanoparticles are discussed. It is possible that magnetic nanoparticles can be applied sustainably after detailed consideration of these discussed factors.

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

    PubMed

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

    2012-09-10

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

  20. Ac magnetic susceptibility study of in vivo nanoparticle biodistribution

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

  1. Dynamic Hysteresis in Compacted Magnetic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Chowdary, Krishna M.

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

  2. Covalent attachment of nanoparticles to copolymer surfaces to control structure-property relationships

    NASA Astrophysics Data System (ADS)

    McConnell, Marla D.

    Interest in functional nanoparticles has increased in recent years, because their small size gives them unique properties. Surface assembly of nanoparticles is particularly appealing, because it can create surfaces with tunable wetting and optical properties. This thesis presents a novel method for the covalent assembly of silica nanoparticles on random copolymer films via covalent bonding, and the subsequent analysis of the wetting and optical properties of these functionalized surfaces. First, the kinetics of the covalent attachment of amine-modified silica nanoparticles to poly(styrene-ran-acrylic acid) were investigated. The surface swelling of the copolymer films upon exposure to reaction solvents was studied with in situ AFM. The films' surface roughness controlled the nanoparticle attachment kinetics, as well as the final nanoparticle coverage. For particle diameters on the order of the roughness features, 70% surface coverage was achieved, while particles with diameters much larger than the surface features reached only 30% coverage. The wetting properties of the nanoparticle surfaces were investigated as a function of particle coverage and diameter. At low coverages of small particles, the surfaces exhibited Wenzel-type wetting behavior. At high particle coverages, the surfaces showed Cassie-type wetting. Finally, the particles were observed to sink into the polymer film with increasing reaction time. This sinking, as well as the magnitude of the contact angles achieved at high particle coverages, led to the hypothesis that polymer chains wet onto the surface of the silica particles. Core-shell Janus particles were prepared by electrostatic assembly of gold nanoparticles on the unprotected surfaces of the silica particles. The plasmon resonance absorption of the gold particles underwent a red shift upon formation of closely-packed networks on the silica particle surfaces. By applying gold, chromium, and gold:palladium coatings to the Janus particles and

  3. Ultralow field magnetization reversal of two-body magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, Fei; Lu, Jincheng; Lu, Xiaofeng; Tang, Rujun; Sun, Z. Z.

    2016-08-01

    Field induced magnetization reversal was investigated in a system of two magnetic nanoparticles with uniaxial anisotropies and magnetostatic interaction. By using the micromagnetic simulation, ultralow switching field strength was found when the separation distance between the two particles reaches a critical small value (on nanometer scale) in the perpendicular configuration where the anisotropic axes of the two particles are perpendicular to the separation line. The switching field increases sharply when the separation is away from the critical distance. The ultralow field switching phenomenon was missed in the parallel configuration where both the anisotropic axes are aligned along the separation line of the two particles. The micromagnetic results are consistent with the previous theoretical prediction [J. Appl. Phys. 109, 104303 (2011)] where dipolar interaction between two single-domain magnetic particles was considered. Our present simulations offered further proofs and possibilities for the low-power applications of information storage as the two-body magnetic nanoparticles might be implemented as a composite information bit.

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

    PubMed

    Lee, Jong-Chul; Lee, Sangyoup

    2013-09-01

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

  5. Controlling the density and site of attachment of gold nanoparticles onto the surface of carbon nanotubes.

    PubMed

    Kumar, Suresh; Kaur, Inderpreet; Dharamvir, Keya; Bharadwaj, Lalit M

    2012-03-01

    A facile method for controlling the density and site of attachment of gold nanoparticles onto the surface of carbon nanotubes is demonstrated. Nitric acid based oxidation was carried out to create carboxylic groups exclusively at the ends of carbon nanotubes, whereas oxidation using a mixture of nitric and sulfuric acid with varied reaction time was carried out to control the population of carboxylic groups on the side walls of nanotubes. In turn, 4-aminothiophenol modified gold nanoparticles were covalently interfaced to these carboxylated multi-walled carbon nanotubes in the presence of a zero length cross-linker, 1-ethylene-3-(3-dimethylaminopropyl) carbodiimide. Raman spectroscopic results showed increase in height of disorder band with each of these successive steps, indicating the increase in degree of functionalization of the carbon nanotubes. Fourier transformed infrared spectroscopic analysis affirmed the functionalization of nanostructures and the formation of nanohybrid. Transmission electron and field emission scanning electron microscopic analysis ascertained the attachment of gold nanoparticles to the ends and side walls of the multi-walled carbon nanotubes. The new hybrid nanostructures may find applications in electronic, optoelectronic, and sensing devices.

  6. 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

    2015-06-08

    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.

  7. Magnetic nanoparticles for applications in oscillating magnetic field

    SciTech Connect

    Peeraphatdit, Chorthip

    2009-01-01

    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

  8. Protein-functionalized magnetic iron oxide nanoparticles: time efficient potential-water treatment

    NASA Astrophysics Data System (ADS)

    Okoli, Chuka; Boutonnet, Magali; Järås, Sven; Rajarao-Kuttuva, Gunaratna

    2012-10-01

    Recent advances in nanoscience suggest that the existing issues involving water quality could be resolved or greatly improved using nanomaterials, especially magnetic iron oxide nanoparticles. Magnetic nanoparticles have been synthesized for the development and use, in association with natural coagulant protein for water treatment. The nanoparticles size, morphology, structure, and magnetic properties were characterized by transmission electron microscope, X-ray diffraction, and superconducting quantum interference device magnetometry. Purified Moringa oleifera protein was attached onto microemulsions-prepared magnetic iron oxide nanoparticles (ME-MION) to form stable protein-functionalized magnetic nanoparticles (PMO+ME-MION). The turbidity removal efficiency in both synthetic and surface water samples were investigated and compared with the commonly used synthetic coagulant (alum) as well as PMO. More than 90 % turbidity could be removed from the surface waters within 12 min by magnetic separation of PMO+ME-MION; whereas gravimetrically, 70 % removal in high and low turbid waters can be achieved within 60 min. In contrast, alum requires 180 min to reduce the turbidity of low turbid water sample. These data support the advantage of separation with external magnetic field (magnetophoresis) over gravitational force. Time kinetics studies show a significant enhancement in ME-MION efficiency after binding with PMO implying the availability of large surface of the ME-MION. The coagulated particles (impurities) can be removed from PMO+ME-MION by washing with mild detergent or cleaning solution. To our knowledge, this is the first report on surface water turbidity removal using protein-functionalized magnetic nanoparticle.

  9. Cellulase immobilization on magnetic nanoparticles encapsulated in polymer nanospheres.

    PubMed

    Lima, Janaina S; Araújo, Pedro H H; Sayer, Claudia; Souza, Antonio A U; Viegas, Alexandre C; de Oliveira, Débora

    2017-04-01

    Immobilization of cellulases on magnetic nanoparticles, especially magnetite nanoparticles, has been the main approach studied to make this enzyme, economically and industrially, more attractive. However, magnetite nanoparticles tend to agglomerate, are very reactive and easily oxidized in air, which has strong impact on their useful life. Thus, it is very important to provide proper surface coating to avoid the mentioned problems. This study aimed to investigate the immobilization of cellulase on magnetic nanoparticles encapsulated in polymeric nanospheres. The support was characterized in terms of morphology, average diameter, magnetic behavior and thermal decomposition analyses. The polymer nanospheres containing encapsulated magnetic nanoparticles showed superparamagnetic behavior and intensity average diameter about 150 nm. Immobilized cellulase exhibited broader temperature stability than in the free form and great reusability capacity, 69% of the initial enzyme activity was maintained after eight cycles of use. The magnetic support showed potential for cellulase immobilization and allowed fast and easy biocatalyst recovery through a single magnet.

  10. Inverted Linear Halbach Array for Separation of Magnetic Nanoparticles.

    PubMed

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

    2013-07-01

    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.

  11. 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

  12. 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.

  13. Attaching Copper Wires to Magnetic-Reed-Switch Leads

    NASA Technical Reports Server (NTRS)

    Kamila, Rudolf

    1987-01-01

    Bonding method reliably joins copper wires to short iron-alloy leads from glass-encased dry magnetic-reed switch without disturbing integrity of glass-to-metal seal. Joint resistant to high temperatures and has low electrical resistance.

  14. 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.

  15. Magnetic nanoparticles for biomedical NMR-based diagnostics

    PubMed Central

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

    2010-01-01

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

  16. Magnetorelaxometry assisting biomedical applications of magnetic nanoparticles.

    PubMed

    Wiekhorst, Frank; Steinhoff, Uwe; Eberbeck, Dietmar; Trahms, Lutz

    2012-05-01

    Due to their biocompatibility and small size, iron oxide magnetic nanoparticles (MNP) can be guided to virtually every biological environment. MNP are susceptible to external magnetic fields and can thus be used for transport of drugs and genes, for heat generation in magnetic hyperthermia or for contrast enhancement in magnetic resonance imaging of biological tissue. At the same time, their magnetic properties allow one to develop sensitive and specific measurement methods to non-invasively detect MNP, to quantify MNP distribution in tissue and to determine their binding state. In this article, we review the application of magnetorelaxometry (MRX) for MNP detection. The underlying physical properties of MNP responsible for the generation of the MRX signal with its characteristic parameters of relaxation amplitude and relaxation time are described. Existing single and multi-channel MRX devices are reviewed. Finally, we thoroughly describe some applications of MRX to cellular MNP quantification, MNP organ distribution and MNP-based binding assays. Providing specific MNP signals, a detection limit down to a few nanogram MNP, in-vivo capability in conscious animals and measurement times of a few seconds, MRX is a valuable tool to improve the application of MNP for diagnostic and therapeutic purposes.

  17. 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.

  18. Photo-Switching of Magnetization in Iron Nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

  19. Biochemical and biomedical applications of multifunctional magnetic nanoparticles: a review

    NASA Astrophysics Data System (ADS)

    Huang, Shih-Hung; Juang, Ruey-Shin

    2011-10-01

    Nanotechnology offers tremendous potential for future medical diagnosis and therapy. Various types of nanoparticles have been extensively studied for numerous biochemical and biomedical applications. Magnetic nanoparticles are well-established nanomaterials that offer controlled size, ability to be manipulated by an external magnetic field, and enhancement of contrast in magnetic resonance imaging. As a result, these nanoparticles could have many applications including bacterial detection, protein purification, enzyme immobilization, contamination decorporation, drug delivery, hyperthermia, etc. All these biochemical and biomedical applications require that these nanoparticles should satisfy some prerequisites including high magnetization, good stability, biocompatibility, and biodegradability. Because of the potential benefits of multimodal functionality in biomedical applications, in this account highlights some general strategies to generate magnetic nanoparticle-based multifunctional nanostructures. After these magnetic nanoparticles are conjugated with proper ligands (e.g., nitrilotriacetate), polymers (e.g., polyacrylic acid, chitosan, temperature- and pH-sensitive polymers), antibodies, enzymes, and inorganic metals (e.g., gold), such biofunctional magnetic nanoparticles exhibit many advantages in biomedical applications. In addition, the multifunctional magnetic nanoparticles have been widely applied in biochemical fields including enzyme immobilization and protein purification.

  20. Magnetic-Field-Assisted Assembly of Anisotropic Superstructures by Iron Oxide Nanoparticles and Their Enhanced Magnetism.

    PubMed

    Jiang, Chengpeng; Leung, Chi Wah; Pong, Philip W T

    2016-12-01

    Magnetic nanoparticle superstructures with controlled magnetic alignment and desired structural anisotropy hold promise for applications in data storage and energy storage. Assembly of monodisperse magnetic nanoparticles under a magnetic field could lead to highly ordered superstructures, providing distinctive magnetic properties. In this work, a low-cost fabrication technique was demonstrated to assemble sub-20-nm iron oxide nanoparticles into crystalline superstructures under an in-plane magnetic field. The gradient of the applied magnetic field contributes to the anisotropic formation of micron-sized superstructures. The magnitude of the applied magnetic field promotes the alignment of magnetic moments of the nanoparticles. The strong dipole-dipole interactions between the neighboring nanoparticles lead to a close-packed pattern as an energetically favorable configuration. Rod-shaped and spindle-shaped superstructures with uniform size and controlled spacing were obtained using spherical and polyhedral nanoparticles, respectively. The arrangement and alignment of the superstructures can be tuned by changing the experimental conditions. The two types of superstructures both show enhancement of coercivity and saturation magnetization along the applied field direction, which is presumably associated with the magnetic anisotropy and magnetic dipole interactions of the constituent nanoparticles and the increased shape anisotropy of the superstructures. Our results show that the magnetic-field-assisted assembly technique could be used for fabricating nanomaterial-based structures with controlled geometric dimensions and enhanced magnetic properties for magnetic and energy storage applications.

  1. In vitro and in vivo anticancer activity of surface modified paclitaxel attached hydroxyapatite and titanium dioxide nanoparticles.

    PubMed

    Venkatasubbu, G Devanand; Ramasamy, S; Reddy, G Pramod; Kumar, J

    2013-08-01

    Targeted drug delivery using nanocrystalline materials delivers the drug at the diseased site. This increases the efficacy of the drug in killing the cancer cells. Surface modifications were done to target the drug to a particular receptor on the cell surface. This paper reports synthesis of hydroxyapatite and titanium dioxide nanoparticles and modification of their surface with polyethylene glycol (PEG) followed by folic acid (FA). Paclitaxel, an anticancer drug, is attached to functionalized hydroxyapatite and titanium dioxide nanoparticles. The pure and functionalised nanoparticles are characterised with XRD, TEM and UV spectroscopy. Anticancer analysis was carried out in DEN induced hepatocarcinoma animals. Biochemical, hematological and histopathological analysis show that the surface modified paclitaxel attached nanoparticles have an higher anticancer activity than the pure paclitaxel and surface modified nanoparticles without paclitaxel. This is due to the targeting of the drug to the folate receptor in the cancer cells.

  2. 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).

  3. Nonlinear Susceptibility Magnitude Imaging of Magnetic Nanoparticles.

    PubMed

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

    2015-03-15

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

  4. 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

  5. Towards magnetic-enhanced cellular uptake, MRI and chemotherapeutics delivery by magnetic mesoporous silica nanoparticles.

    PubMed

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

    2012-10-01

    A type of nanoparticle with three functional modalities was prepared with the aim of providing a multifunctional drug delivery system. The nanoparticle was 50 nm in size, with 2.7 nm mesopores and a magnetic nanocrystal core, which was further doped with FITC to enable the tracking of cellular uptake. We demonstrated that the internalization of the nanoparticles in tumor cells could be enhanced by applying an external magnetic field and furthermore, this kind of nanoparticle could be used in magnetic targeted drug delivery. With high transverse relaxivity, the magnetic nanoparticles shortened proton relaxation time and induced high magnetic resonance imaging contrast in tumor cells. Studies on anticancer drug loading and delivery capacity of anticancer drugs also showed that this type of nanoparticles could load water-soluble doxorubicin, and produce a prominent inhibitive effect against tumor cells. Taken together, the presented nanoparticles could become a promising agent in cancer theranostics.

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

    NASA Astrophysics Data System (ADS)

    Balakrishnan, Srinivasan

    Magnetic nanoparticles have recently attracted much attention for potential biomedical applications such as targeted drug delivery, magnetic resonance imaging contrast agents and hyperthermia treatment of cancerous cells. Future research on biomedical applications also includes use of magnetic nanoparticles for cell and DNA separation. By functionalizing magnetic nanoparticles with cells or DNA selective biomolecules, the particles attach to the target and are removed from the sample upon passing through magnetic field gradients. The field gradients apply a force that attracts the particles given by the equation F = ∇(m · B), where m is the magnetization of the MNP, and B is the applied magnetic field. This type of magnetic manipulation is potential for in vivo applications such as targeted drug delivery, magnetic resonance imaging contrast enhancement and hyperthermia treatment of cancer. The magnitude of the field gradients of magnetic nanoparticles are significantly reduced due to the inverse square law dependence of magnetic field strength and subsequently the forces set up are reduced. Although the research in this field has focused primarily on iron oxide nanoparticles, these oxide nanoparticles have a low magnetization that renders them ineffective, at the distances required for in vivo applications, due to the reduced forces felt by the nanoparticles. Successful implementation of such magnetic nanoparticles based system in vivo may require higher magnetization. The aim of this proposal is to synthesize high magnetization Fe-based MNPs functionalized with artificial proteins. The research described in this dissertation focuses on synthesis, size control, structural and magnetic characterization and associated experimental studies to characterize their properties for application in magnetic fluid hyperthermia and magnetic resonance imaging applications. The method used for the synthesis of the Fe-based nanoparticles is the conventional borohydride

  7. Removal of Radioactive Cesium Using Prussian Blue Magnetic Nanoparticles

    PubMed Central

    Jang, Sung-Chan; Hong, Sang-Bum; Yang, Hee-Man; Lee, Kune-Woo; Moon, Jei-Kwon; Seo, Bum-Kyoung; Huh, Yun Suk; Roh, Changhyun

    2014-01-01

    Radioactive cesium (137Cs) has inevitably become a human concern due to exposure from nuclear power plants and nuclear accident releases. Many efforts have been focused on removing cesium and the remediation of the contaminated environment. In this study, we elucidated the ability of Prussian blue-coated magnetic nanoparticles to eliminate cesium from radioactive contaminated waste. Thus, the obtained Prussian blue-coated magnetic nanoparticles were then characterized and examined for their physical and radioactive cesium adsorption properties. This Prussian blue-coated magnetic nanoparticle-based cesium magnetic sorbent can offer great potential for use in in situ remediation. PMID:28344255

  8. Fe-based nanoparticles as tunable magnetic particle hyperthermia agents

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  9. Size and property bimodality in magnetic nanoparticle dispersions: single domain particles vs. strongly coupled nanoclusters.

    PubMed

    Wetterskog, E; Castro, A; Zeng, L; Petronis, S; Heinke, D; Olsson, E; Nilsson, L; Gehrke, N; Svedlindh, P

    2017-03-23

    The widespread use of magnetic nanoparticles in the biotechnical sector puts new demands on fast and quantitative characterization techniques for nanoparticle dispersions. In this work, we report the use of asymmetric flow field-flow fractionation (AF4) and ferromagnetic resonance (FMR) to study the properties of a commercial magnetic nanoparticle dispersion. We demonstrate the effectiveness of both techniques when subjected to a dispersion with a bimodal size/magnetic property distribution: i.e., a small superparamagnetic fraction, and a larger blocked fraction of strongly coupled colloidal nanoclusters. We show that the oriented attachment of primary nanocrystals into colloidal nanoclusters drastically alters their static, dynamic, and magnetic resonance properties. Finally, we show how the FMR spectra are influenced by dynamical effects; agglomeration of the superparamagnetic fraction leads to reversible line-broadening; rotational alignment of the suspended nanoclusters results in shape-dependent resonance shifts. The AF4 and FMR measurements described herein are fast and simple, and therefore suitable for quality control procedures in commercial production of magnetic nanoparticles.

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

    NASA Astrophysics Data System (ADS)

    Beveridge, Jacob S.

    Magnetic nanoparticles uniquely combine superparamagnetic behavior with dimensions that are smaller than or the same size as molecular analytes. The integration of magnetic nanoparticles with analytical methods has opened new avenues for sensing, purification, and quantitative analysis. Applied magnetic fields can be used to control the motion and properties of magnetic nanoparticles; in analytical chemistry, use of magnetic fields provides methods for manipulating and analyzing species at the molecular level. The ability to use applied magnetic fields to control the motion and properties of magnetic nanoparticles is a tool for manipulating and analyzing species at the molecular level, and has led to applications including analyte handing, chemical sensors, and imaging techniques. This is clearly an area where significant growth and impact in separation science and analysis is expected in the future. In Chapter 1, we describe applications of magnetic nanoparticles to analyte handling, chemical sensors, and imaging techniques. Chapter 2 reports the purification and separation of magnetic nanoparticle mixtures using the technique developed in our lab called differential magnetic catch and release (DMCR). This method applies a variable magnetic flux orthogonal to the flow direction in an open tubular capillary to trap and controllably release magnetic nanoparticles. Magnetic moments of 8, 12, and 17 nm diameter CoFe2O4 nanoparticles are calculated using the applied magnetic flux density and experimentally determined force required to trap 50% of the particle sample. Balancing the relative strengths of the drag and magnetic forces enable separation and purification of magnetic CoFe2 O4 nanoparticle samples with < 20 nm diameters. Samples were characterized by transmission electron microscopy to determine the average size and size dispersity of the sample population. DMCR is further demonstrated to be useful for separation of a magnetic nanoparticle mixture, resulting

  11. Biomedical and environmental applications of magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

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

    PubMed Central

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

    2009-01-01

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

  13. 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

  14. Extraordinary Hall-effect in colloidal magnetic nanoparticle films

    NASA Astrophysics Data System (ADS)

    Ben Gur, Leah; Tirosh, Einat; Segal, Amir; Markovich, Gil; Gerber, Alexander

    2017-03-01

    Colloidal nickel nanoparticles (NPs) coated with polyvinylpyrrolidone (PVP) were synthesized. The nanoparticle dispersions were deposited on substrates and dried under mild heating to form conductive films. The films exhibited very small coercivity, nearly metallic conductivity, and a significant extraordinary Hall effect signal. This method could be useful for preparing simple, printed magnetic field sensors with the advantage of relatively high sensitivity around zero magnetic field, in contrast to magnetoresistive sensors, which have maximal field sensitivity away from zero magnetic field.

  15. Peptide-functionalized magnetic nanoparticles for cancer therapy applications

    NASA Astrophysics Data System (ADS)

    Hauser, Anastasia Kruse

    Lung cancer is one of the leading causes of cancer deaths in the United States. Radiation and chemotherapy are conventional treatments, but they result in serious side effects and the probability of tumor recurrence remains high. Therefore, there is an increasing need to enhance the efficacy of conventional treatments. Magnetic nanoparticles have been previously studied for a variety of applications such as magnetic resonance imaging contrast agents, anemia treatment, magnetic cell sorting and magnetically mediated hyperthermia (MMH). In this work, dextran coated iron oxide nanoparticles were developed and functionalized with peptides to target the nanoparticles to either the extracellular matrix (ECM) of tumor tissue or to localize the nanoparticles in subcellular regions after cell uptake. The magnetic nanoparticles were utilized for a variety of applications. First, heating properties of the nanoparticles were utilized to administer hyperthermia treatments combined with chemotherapy. The nanoparticles were functionalized with peptides to target fibrinogen in the ECM and extensively characterized for their physicochemical properties, and MMH combined with chemotherapy was able to enhance the toxicity of chemotherapy. The second application of the nanoparticles was magnetically mediated energy delivery. This treatment does not result in a bulk temperature rise upon actuation of the nanoparticles by an alternating magnetic field (AMF) but rather results in intracellular damage via friction from Brownian rotation or nanoscale heating effects from Neel relaxations. The nanoparticles were functionalized with a cell penetrating peptide to facilitate cell uptake and lysosomal escape. The intracellular effects of the internalized nanoparticles alone and with activation by an AMF were evaluated. Iron concentrations in vivo are highly regulated as excess iron can catalyze the formation of the hydroxyl radical through Fenton chemistry. Although often a concern of using iron

  16. Promising iron oxide-based magnetic nanoparticles in biomedical engineering.

    PubMed

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

    2012-12-01

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

  17. Composite Materials with Magnetically Aligned Carbon Nanoparticles Having Enhanced Electrical Properties and Methods of Preparation

    NASA Technical Reports Server (NTRS)

    Hong, Haiping (Inventor); Peterson, G.P. (Bud) (Inventor); Salem, David R. (Inventor)

    2016-01-01

    Magnetically aligned carbon nanoparticle composites have enhanced electrical properties. The composites comprise carbon nanoparticles, a host material, magnetically sensitive nanoparticles and a surfactant. In addition to enhanced electrical properties, the composites can have enhanced mechanical and thermal properties.

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

    PubMed

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

    2015-03-21

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

  19. Magnetic nanoparticle-based cancer nanodiagnostics

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  20. Oxidation and magnetic properties of lead nanoparticles in different matrices

    NASA Astrophysics Data System (ADS)

    Sarkar, A.; Chadha, R.; Mukherjee, T.; Kapoor, S.

    2009-04-01

    A systematic study was conducted for in situ synthesis of fine Pb nanoparticles in aqueous gelatin solution and in pre-organized gel of polyacrylamide. The Pb nanoparticles stabilized by gelatin or trapped in polyacrylamide matrix transfer electron to O 2 and methyl viologen (paraquat; 1,1'-dimethyl-4,4'-dipyridinium dichloride; MV 2+(Cl -) 2). Lead nanoparticles were probed for their magnetic characteristics by superconducting quantum interference device (SQUID) magnetometer and display superconductivity with a critical temperature T c of about 7.1 K. The magnetization measurements reveal the superconducting behaviour of Pb nanoparticles prepared in aqueous gelatin stabilized sol and corroborates the results obtained from electron transfer reactions.

  1. Size control of magnetic carbon nanoparticles for drug delivery.

    PubMed

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

    2010-02-01

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

  2. Attempt to remove peanut allergens from peanut extracts, using IgE-attached magnetic beads.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Immunoglobulin E (IgE) antibodies from sera of peanut-allergic individuals are known to bind specifically to major peanut allergens, Ara h 1 and Ara h 2. The objective of this study was to determine the efficiency of magnetic beads (Dynabeads) attached with IgE antibodies in the removal of major pea...

  3. Measurement of Nanoparticle Magnetic Hyperthermia Using Fluorescent Microthermal Imaging

    NASA Astrophysics Data System (ADS)

    Zheng, Xiaowan; van Keuren, Edward

    Nanoparticle magnetic hyperthermia uses the application of an AC magnetic field to ferromagnetic nanoparticles to elevate the temperature of cancer cells. The principle of hyperthermia as a true cell-specific therapy is that tumor cells are more sensitive to high temperature, so it is of great importance to control the locality and magnitude of the temperature differences. One technique to measure temperature variations on microscopic length scales is fluorescent microthermal imaging (FMI). Since it is the local temperature that is measured in FMI, effects such as heating due to nearby field coils can be accounted for. A dye, the rare earth chelate europium thenoyltrifluoroacetonate (Eu:TTA), with a strong temperature-dependent fluorescence emission has been incorporated into magnetic nanoparticles dispersed in a polymer films. FMI experiments were carried out on these samples under an applied high frequency magnetic field. Preliminary results show that FMI is a promising technique for characterizing the local generation of heat in nanoparticle magnetic hyperthermia.

  4. 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.

  5. Amine-functionalized magnetic nanoparticles for rapid capture and removal of bacterial pathogens.

    PubMed

    Huang, Yan-Feng; Wang, Ya-Fan; Yan, Xiu-Ping

    2010-10-15

    Interest in magnetic nanoparticles for capturing bacteria arises from a variety of attributes, including the similar size of nanoparticles, magnetic behavior, and attached biomolecules such as proteins and nucleotide probes. Here we report the application of amine-functionalized magnetic nanoparticles (AF-MNPs) for rapid and efficient capture and removal of bacterial pathogens. The AF-MNPs are used without the need for any further modifications with affinity biomolecules. The positive charges on the surface of AF-MNPs can promote strong electrostatic interaction with negatively charged sites on the surface of bacterial pathogens to exhibit efficient adsorptive ability. The hydrophobic interaction between the pendant propyl group of the amine functionality and the bacteria also plays a supplementary role. The amine groups on the surface of the magnetic nanoparticle are robust and inexpensive ligands to ensure a high binding affinity to at least eight different species of Gram-positive and Gram-negative bacteria. The amount of AF-MNPs, pH of phosphate buffer solution, and ionic strength are crucial in mediating fast and effective interactions between AF-MNPs and bacteria. The AF-MNPs allow rapid removal of bacteria from water samples, food matrixes, and a urine sample with efficiency from 88.5% to 99.1%. Though amino group offers less specificity/selectivity than biomolecules such as antibodies, AF-MNPs are attractive for capturing a wide range of bacteria.

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

    PubMed

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

    2008-09-10

    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-gamma) on negatively charged magnetic nanoparticles prepared by three different methods, including coprecipitation, decomposition in organic media, and laser pyrolysis. To facilitate IFN-gamma adsorption, magnetic nanoparticles were surface modified by distinct molecules to achieve high negative charge at pH 7, maintaining small aggregate size and stability in biological media. We analyzed carboxylate-based coatings and studied the colloidal properties of the resulting dispersions. Finally, we incubated the magnetic dispersions with IFN-gamma and determined optimal conditions for protein adsorption onto the particles, as well as the release capacity at different pH and as a function of time. Particles prepared by decomposition in organic media and further modified with dimercaptosuccinic acid showed the most efficient adsorption/release capacity. IFN-gamma adsorbed on these nanoparticles would allow concentration of this protein or other biomolecules at specific sites for treatment of cancer or other diseases.

  7. Microfluidic magnetic switching valves based on aggregates of magnetic nanoparticles: Effects of aggregate length and nanoparticle sizes

    NASA Astrophysics Data System (ADS)

    Jiemsakul, Thanakorn; Manakasettharn, Supone; Kanharattanachai, Sivakorn; Wanna, Yongyuth; Wangsuya, Sujint; Pratontep, Sirapat

    2017-01-01

    We demonstrate microfluidic switching valves using magnetic nanoparticles blended within the working fluid as an alternative microfluidic flow control in microchannels. Y-shaped microchannels have been fabricated by using a CO2 laser cutter to pattern microchannels on transparent poly(methyl methacrylate) (PMMA) sheets covered with thermally bonded transparent polyvinyl chloride (PVC) sheets. To examine the performance of the microfluidic magnetic switching valves, an aqueous magnetic nanoparticle suspension was injected into the microchannels by a syringe pump. Neodymium magnets were then employed to attract magnetic nanoparticles and form an aggregate that blocked the microchannels at a required position. We have found that the maximum volumetric flow rate of the syringe pump that the magnetic nanoparticle aggregate can withstand scales with the square of the external magnetic flux density. The viscosity of the fluid exhibits dependent on the aggregate length and the size of the magnetic nanoparticles. This microfluidic switching valve based on aggregates of magnetic nanoparticles has strong potentials as an on-demand flow control, which may help simplifying microfluidic channel designs.

  8. Bacterially synthesized ferrite nanoparticles for magnetic hyperthermia applications.

    PubMed

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

    2014-11-07

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

  9. Inhalable Magnetic Nanoparticles for Targeted Hyperthermia in Lung Cancer Therapy

    PubMed Central

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

    2015-01-01

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

  10. Functionalization of polydopamine coated magnetic nanoparticles with biological entities

    NASA Astrophysics Data System (ADS)

    Mǎgeruşan, Lidia; Mrówczyński, Radosław; Turcu, Rodica

    2015-12-01

    New hybrid materials, obtained through introduction of cysteine, lysine and folic acid as biological entities into polydopamine-coated magnetite nanoparticles, are reported. The syntheses are straight forward and various methods were applied for structural and morphological characterization of the resulting nanoparticles. XPS proved a very powerful tool for surface chemical analysis and it evidences the functionalization of polydopamine coated magnetite nanoparticles. The superparamagnetic behavior and the high values of saturation magnetization recommend all products for further application where magnetism is important for targeting, separation, or heating by alternative magnetic fields.

  11. Magnetic properties of superparamagnetic nanoparticles loaded into silicon nanotubes

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  12. Dynamics of magnetic nanoparticles in viscoelastic media

    NASA Astrophysics Data System (ADS)

    Remmer, Hilke; Roeben, Eric; Schmidt, Annette M.; Schilling, Meinhard; Ludwig, Frank

    2017-04-01

    We compare different models for the description of the complex susceptibility of magnetic nanoparticles in an aqueous gelatin solution representing a model system for a Voigt-Kelvin scheme. The analysis of susceptibility spectra with the numerical model by Raikher et al. [7] is compared with the analysis applying a phenomenological, modified Debye model. The fit of the models to the measured data allows one to extract the viscoelastic parameter dynamic viscosity η and shear modulus G. The experimental data were recorded on single-core thermally blocked CoFe2O4 nanoparticles in an aqueous solution with 2.5 wt% gelatin. Whereas the dynamic viscosities obtained by fitting the model - extended by distributions of hydrodynamic diameters and viscosities - agree very well, the derived values for the shear modulus show the same temporal behavior during the gelation process, but vary approximately by a factor of two. To verify the values for viscosity and shear modulus obtained from nanorheology, macrorheological measurements are in progress.

  13. Radiolabeled theranostics: magnetic and gold nanoparticles

    PubMed Central

    Same, Saeideh; Aghanejad, Ayuob; Akbari Nakhjavani, Sattar; Barar, Jaleh; Omidi, Yadollah

    2016-01-01

    Introduction: Growing advances in nanotechnology have facilitated the applications of newly emerged nanomaterials in the field of biomedical/pharmaceutical sciences. Following this trend, the multifunctional nanoparticles (NPs) play a significant role in development of advanced drug delivery systems (DDSs) such as diapeutics/theranostics used for simultaneous diagnosis and therapy. Multifunctional radiolabeled NPs with capability of detecting, visualizing and destroying diseased cells with least side effects have been considered as an emerging filed in presentation of the best choice in solving the therapeutic problems. Functionalized magnetic and gold NPs (MNPs and GNPs, respectively) have produced the potential of nanoparticles as sensitive multifunctional probes for molecular imaging, photothermal therapy and drug delivery and targeting. Methods: In this study, we review the most recent works on the improvement of various techniques for development of radiolabeled magnetic and gold nanoprobes, and discuss the methods for targeted imaging and therapies. Results: The receptor-specific radiopharmaceuticals have been developed to localized radiotherapy in disease sites. Application of advanced multimodal imaging methods and related modality imaging agents labeled with various radioisotopes (e.g., 125I, 111In, 64Cu, 68Ga, 99mTc) and MNPs/GNPs have significant effects on treatment and prognosis of cancer therapy. In addition, the surface modification with biocompatible polymer such as polyethylene glycol (PEG) have resulted in development of stealth NPs that can evade the opsonization and immune clearance. These long-circulating agents can be decorated with homing agents as well as radioisotopes for targeted imaging and therapy purposes. Conclusion: The modified MNPs or GNPs have wide applications in concurrent diagnosis and therapy of various malignancies. Once armed with radioisotopes, these nanosystems (NSs) can be exploited for combined multimodality imaging with

  14. Physical and magnetic properties of magnetic nanoparticle arrays

    NASA Astrophysics Data System (ADS)

    Mohtasebzadeh, Abdul Rahman

    Using Scanning Electron Microscope (SEM) , Atomic Force Microscope (AFM) and Vibrating Sample Magnetometer (VSM) I studied magnetic-field directed selfassembly of magnetic nanoparticles into patterned arrays on the surface of perpendicular magnetic recording media. A controllable machine was used to coat super paramagnetic nano particles onto the surface of perpendicular recording media for different time intervals. Self assembled nano particles on the surface of the media, were transferred to a polymer layer to observe physical properties. Results from imaging shows that the average width and height of arrays is increasing as a function of time. Width of arrays with assembly time varies from 100nm at 5 minutes to 500nm at 120 minutes. Similarly, height changes from 13nm at 5 minutes to 37nm at 120 minutes. Therefore the pattern aspect ratio changes from 8:1 at 5 minutes to 14:1 at 120 minutes. For large widths compared with pattern spacing, array interaction appears as a slope change in VSM hysteresis loops. The hypothesis is that the difference in slope as a function of time for two cases; patterns oriented parallel and perpendicular to the external field is caused by array interaction; in other words wider patterns interact with each other more than narrower patterns.

  15. Immobilization of bovine catalase onto magnetic nanoparticles.

    PubMed

    Doğaç, Yasemin İspirli; Teke, Mustafa

    2013-01-01

    The scope of this study is to achieve carrier-bound immobilization of catalase onto magnetic particles (Fe₃O₄ and Fe₂O₃NiO₂ · H₂O) to specify the optimum conditions of immobilization. Removal of H2O2 and the properties of immobilized sets were also investigated. To that end, adsorption and then cross-linking methods onto magnetic particles were performed. The optimum immobilization conditions were found for catalase: immobilization time (15 min for Fe₃O₄; 10 min for Fe2O₃NiO₂ · H₂O), the initial enzyme concentration (1 mg/mL), amount of magnetic particles (25 mg), and glutaraldehyde concentration (3%). The activity reaction conditions (optimum temperature, optimum pH, pH stability, thermal stability, operational stability, and reusability) were characterized. Also kinetic parameters were calculated by Lineweaver-Burk plots. The optimum pH values were found to be 7.0, 7.0, and 8.0 for free enzyme, Fe₃O₄-immobilized catalases, and Fe₂O₃NiO₂ · H₂O-immobilized catalases, respectively. All immobilized catalase systems displayed the optimum temperature between 25 and 35°C. Reusability studies showed that Fe₃O₄-immobilized catalase can be used 11 times with 50% loss in original activity, while Fe2O₃NiO₂ · H₂O-immobilized catalase lost 67% of activity after the same number of uses. Furthermore, immobilized catalase systems exhibited improved thermal and pH stability. The results transparently indicate that it is possible to have binding between enzyme and magnetic nanoparticles.

  16. Magnetic nanoparticles: surface effects and properties related to biomedicine applications.

    PubMed

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

    2013-10-25

    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 μm), 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.

  17. Magnetic nanoparticles for bio-analytical applications

    NASA Astrophysics Data System (ADS)

    Yedlapalli, Sri Lakshmi

    Magnetic nanoparticles are widely being used in various fields of medicine, biology and separations. This dissertation focuses on the synthesis and use of magnetic nanoparticles for targeted drug delivery and analytical separations. The goals of this research include synthesis of biocompatible surface modified monodisperse superparamagnetic iron oxide nanoparticles (SPIONs) by novel techniques for targeted drug delivery and use of SPIONs as analytical sensing tools. Surface modification of SPIONs was performed with two different co-polymers: tri block co-polymer Pluronics and octylamine modified polyacrylic acid. Samples of SPIONs were subsequently modified with 4 different commercially available, FDA approved tri-block copolymers (Pluronics), covering a wide range of molecular weights (5.75-14.6 kDa). A novel, technically simpler and faster phase transfer approach was developed to surface modify the SPIONs with Pluronics for drug delivery and other biomedical applications. The hydrodynamic diameter and aggregation properties of the Pluronic modified SPIONs were studied by dynamic light scattering (DLS). The coverage of SPIONs with Pluronics was supported with IR Spectroscopy and characterized by Thermo gravimetric Analysis (TGA). The drug entrapment capacity of SPIONs was studied by UV-VIS spectroscopy using a hydrophobic carbocyanine dye, which serves as a model for hydrophobic drugs. These studies resulted in a comparison of physical properties and their implications for drug loading capacities of the four types of Pluronic coated SPIONs for drug delivery assessment. These drug delivery systems could be used for passive drug targeting. However, Pluronics lack the functional group necessary for bioconjugation and hence cannot achieve active targeting. SPIONs were functionalized with octylamine modified polyacrylic acid-based copolymer, providing water solubility and facile biomolecular conjugation. Epirubicin was loaded onto SPIONs and the drug entrapment was

  18. Ultrasensitive detection and molecular imaging with magnetic nanoparticles.

    PubMed

    Yang, Jian; Gunn, Jonathan; Dave, Shivang R; Zhang, Miqin; Wang, Y Andrew; Gao, Xiaohu

    2008-02-01

    Recent advances in nanotechnology have produced a variety of nanoparticles ranging from semiconductor quantum dots (QDs), magnetic nanoparticles (MNPs), metallic nanoparticles, to polymeric nanoparticles. Their unique electronic, magnetic, and optical properties have enabled a broad spectrum of biomedical applications such as ultrasensitive detection, medical imaging, and specific therapeutics. MNPs made from iron oxide, in particular, have attracted extensive interest and have already been used in clinical studies owing to their capability of deep-tissue imaging, non-immunogenesis, and low toxicity. In this Research Highlight article, we attempt to highlight the recent breakthroughs in MNP synthesis based on a non-hydrolytic approach, nanoparticle (NP) surface engineering, their unique structural and magnetic properties, and current applications in ultrasensitive detection and imaging with a special focus on innovative bioassays. We will also discuss our perspectives on future research directions.

  19. Synthesis of a novel biocompatible nanocomposite of graphene oxide and magnetic nanoparticles for drug delivery.

    PubMed

    Aliabadi, Majid; Shagholani, Hamidreza; Yunessnia Lehi, Arash

    2017-05-01

    The combination of imaging and delivery systems through nanoscale material have been used to create new nanoparticle formulations for biological applications. Here, a magnetic nanocomposite consisting of superparamagnetic iron oxide nanoparticles (SPIONs), graphene oxide (GO), chitosan and poly(vinyl alcohol) (PVA) as biocompatible polymers was synthesized for applying in drug delivery and imaging agent. The nanocomposite was studied by various techniques including XRD, TEM, FE-SEM, FT-IR and VSM. SPIONs had an average diameter size about 10nm and showed superparamagnetic behavior. Also, TEM and SEM images showed that these nanoparticles successfully attached on the surface of GO sheets. Finally, 5-fu was loaded onto these nanocomposite particles in order to study of entrapment efficiency and drug release behavior of nanocomposite particles. They showed high drug entrapment efficiency and more and faster drug release in acidic pH.

  20. Direct measurement of electrostatic fields using single Teflon nanoparticle attached to AFM tip

    PubMed Central

    2013-01-01

    Abstract A single 210-nm Teflon nanoparticle (sTNP) was attached to the vertex of a silicon nitride (Si3N4) atomic force microscope tip and charged via contact electrification. The charged sTNP can then be considered a point charge and used to measure the electrostatic field adjacent to a parallel plate condenser using 30-nm gold/20-nm titanium as electrodes. This technique can provide a measurement resolution of 250/100 nm along the X- and Z-axes, and the minimum electrostatic force can be measured within 50 pN. PACS 07.79.Lh, 81.16.-c, 84.37. + q PMID:24314111

  1. Mass production of magnetic nickel nanoparticle in thermal plasma reactor

    SciTech Connect

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

    2014-04-24

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

  2. Synthesis and bio-functionalization of magnetic nanoparticles for medical diagnosis and treatment.

    PubMed

    Schladt, Thomas D; Schneider, Kerstin; Schild, Hansjörg; Tremel, Wolfgang

    2011-06-28

    The synthesis of multifunctional magnetic nanoparticles (NPs) is a highly active area of current research located at the interface between materials science, biotechnology and medicine. By virtue of their unique physical properties magnetic nanoparticles are emerging as a new class of diagnostic probes for multimodal tracking and as contrast agents for MRI. Furthermore, they show great potential as carriers for targeted drug and gene delivery, since reactive agents, such as drug molecules or large biomolecules (including genes and antibodies), can easily be attached to their surface. On the other hand, the fate of the nanoparticles inside the body is mainly determined by the interactions with its local environment. These interactions strongly depend upon the size of the magnetic NPs but also on the individual surface characteristics, like charge, morphology and surface chemistry. This review not only summarizes the most common synthetic approaches for the generation of magnetic NPs, it also focuses on different surface modification strategies that are used today to enhance the biocompatibility of these NPs. Finally, key considerations for the application of magnetic NPs in biomedicine, as well as various examples for the utilization in multimodal imaging and targeted gene delivery are presented.

  3. Tailored magnetic nanoparticles for optimizing magnetic fluid hyperthermia.

    PubMed

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

    2012-03-01

    Magnetic Fluid Hyperthermia (MFH) is a promising approach towards adjuvant cancer therapy that is based on the localized heating of tumors using the relaxation losses of iron oxide magnetic nanoparticles (MNPs) in alternating magnetic fields (AMF). In this study, we demonstrate optimization of MFH by tailoring MNP size to an applied AMF frequency. Unlike conventional aqueous synthesis routes, we use organic synthesis routes that offer precise control over MNP size (diameter ∼10 to 25 nm), size distribution, and phase purity. Furthermore, the particles are successfully transferred to the aqueous phase using a biocompatible amphiphilic polymer, and demonstrate long-term shelf life. A rigorous characterization protocol ensures that the water-stable MNPs meet all the critical requirements: (1) uniform shape and monodispersity, (2) phase purity, (3) stable magnetic properties approaching that of the bulk, (4) colloidal stability, (5) substantial shelf life, and (6) pose no significant in vitro toxicity. Using a dedicated hyperthermia system, we then identified that 16 nm monodisperse MNPs (σ-0.175) respond optimally to our chosen AMF conditions (f = 373 kHz, H₀ = 14 kA/m); however, with a broader size distribution (σ-0.284) the Specific Loss Power (SLP) decreases by 30%. Finally, we show that these tailored MNPs demonstrate maximum hyperthermia efficiency by reducing viability of Jurkat cells in vitro, suggesting our optimization translates truthfully to cell populations. In summary, we present a way to intrinsically optimize MFH by tailoring the MNPs to any applied AMF, a required precursor to optimize dose and time of treatment.

  4. Synthesis of magnetic cytosine-imprinted chitosan nanoparticles

    NASA Astrophysics Data System (ADS)

    Lee, Mei-Hwa; Ahluwalia, Arti; Chen, Jian-Zhou; Shih, Neng-Lang; Lin, Hung-Yin

    2017-02-01

    Molecularly imprinted polymer nanoparticles incorporating magnetic nanoparticles (MNPs) have been investigated for their selective adsorption properties. Here we describe the synthesis and characterization of magnetic cytosine-imprinted chitosan nanoparticles (CIPs) for gene delivery. In particular, CIPs carrying the mammalian expression plasmid of enhanced green fluorescent protein were prepared by the co-precipitation of MNPs, chitosan and a template nucleobase (cytosine). The results show that the selective reabsorption of cytosine to magnetic CIPs was at least double that of non-imprinted polymers and other nucleobases (such as adenine and thymine). The gene carrier CIPs were used for the transfection of human embryonic kidney 293 cells showing dramatic increase their efficiency with that of conventional chitosan nanoparticles. Furthermore, the gene carrier magnetic CIPs also exhibit low toxicity compared to that of commercially available cationic lipids.

  5. 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...

  6. Synthesis of magnetic cytosine-imprinted chitosan nanoparticles.

    PubMed

    Lee, Mei-Hwa; Ahluwalia, Arti; Chen, Jian-Zhou; Shih, Neng-Lang; Lin, Hung-Yin

    2017-02-24

    Molecularly imprinted polymer nanoparticles incorporating magnetic nanoparticles (MNPs) have been investigated for their selective adsorption properties. Here we describe the synthesis and characterization of magnetic cytosine-imprinted chitosan nanoparticles (CIPs) for gene delivery. In particular, CIPs carrying the mammalian expression plasmid of enhanced green fluorescent protein were prepared by the co-precipitation of MNPs, chitosan and a template nucleobase (cytosine). The results show that the selective reabsorption of cytosine to magnetic CIPs was at least double that of non-imprinted polymers and other nucleobases (such as adenine and thymine). The gene carrier CIPs were used for the transfection of human embryonic kidney 293 cells showing dramatic increase their efficiency with that of conventional chitosan nanoparticles. Furthermore, the gene carrier magnetic CIPs also exhibit low toxicity compared to that of commercially available cationic lipids.

  7. 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...

  8. 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

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

    PubMed

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

    2015-02-07

    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.

  10. Engineering of magnetic DNA nanoparticles for tumor-targeted therapy

    NASA Astrophysics Data System (ADS)

    Hosseinkhani, Hossein; Chen, Yi-Ru; He, Wenjie; Hong, Po-Da; Yu, Dah-Shyong; Domb, Abraham J.

    2013-01-01

    This study aims to engineer novel targeted delivery system composed of magnetic DNA nanoparticles to be effective as an efficient targeted gene therapy vehicle for tumor therapy. A polysaccharide, dextran, was chosen as the vector of plasmid DNA-encoded NK4 that acts as an HGF-antagonist and anti-angiogenic regulator for inhibitions of tumor growth, invasion, and metastasis. Spermine (Sm) was chemically introduced to the hydroxyl groups of dextran to obtain dextran-Sm. When Fe2+ solution was added to the mixture of dextran-Sm and a plasmid DNA, homogenous DNA nanoparticles were formed via chemical metal coordination bonding with average size of 230 nm. Characterization of DNA nanoparticles was performed via dynamic light scattering measurement, electrophoretic light scattering measurement, as well as transmission electron microscope. DNA nanoparticles effectively condensed plasmid DNA into nanoparticles and enhanced the stability of DNA, while significantly improved transfection efficiency in vitro and tumor accumulation in vivo. In addition, magnetic DNA nanoparticles exhibited high efficiency in antitumor therapy with regards to tumor growth as well as survival of animals evaluated in the presence of external magnetic field. We conclude that the magnetic properties of these DNA nanoparticles would enhance the tracking of non-viral gene delivery systems when administrated in vivo in a test model. These findings suggest that DNA nanoparticles effectively deliver DNA to tumor and thereby inhibiting tumor growth.

  11. Single-domain magnetic nanoparticles in an alternating magnetic field as mediators of local deformation of the surrounding macromolecules

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    The forces, deformations, and stresses generated in macromolecules attached to single-domain magnetic nanoparticles under the influence of a low-frequency (nonheating) magnetic field have been analyzed analytically and numerically. It has been shown that, in bioactive macromolecules, an alternating magnetic field with an induction of 0.1-1.0 T and a circular frequency of ≲104 s-1 can induce forces up to several hundred piconewtons, absolute deformations up to a few tens of nanometers, as well as compressive and shear stresses exceeding 107 Pa. These mechanical stimuli are sufficient for a significant change of interatomic distances in active centers, conformation of macromolecules, and even a breaking of some bonds, which makes it possible to develop a new technological platform for targeted delivery of drugs, remote control of their activity, and cancer-cell destruction.

  12. Bacterially synthesized ferrite nanoparticles for magnetic hyperthermia applications

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  13. Synthesis and application of magnetic chitosan nanoparticles in oilfield

    NASA Astrophysics Data System (ADS)

    Lian, Qi; Zheng, Xuefang

    2016-01-01

    The novel magnetic Co0.5Mn0.5Fe2O4-chitosan nanoparticles has the advantage of excellent biodegradation and a high level of controllability. The Co0.5Mn0.5Fe2O4-chitosan nanoparticles was prepared successfully. The size of the Co0.5Mn0.5Fe2O4-chitosan nanoparticles were all below 100 nm. The saturated magnetization of the Co0.5Mn0.5Fe2O4-chitosan nanoparticles could reach 80 emu/g and showed the characteristics of superparamagnetism at the same time. The image of TEM and SEM electron microscopy showed that the cubic-shape magnetic Co0.5Mn0.5Fe2O4 particles were encapsulated by the spherical chitosan nanoparticles. The evaluation on the interfacial properties of the product showed that the interfacial tension between crude oil and water could be reduce to ultra-low values as low as 10-3 mN/m when the magnetic Co0.5Mn0.5Fe2O4-chitosan nanoparticle was used in several blocks in Shengli Oilfield without other additives. Meanwhile, the magnetic Co0.5Mn0.5Fe2O4-chitosan nanoparticles possessed good salt-resisting capacity.

  14. Application of magnetic nanoparticles in smart enzyme immobilization.

    PubMed

    Vaghari, Hamideh; Jafarizadeh-Malmiri, Hoda; Mohammadlou, Mojgan; Berenjian, Aydin; Anarjan, Navideh; Jafari, Nahideh; Nasiri, Shahin

    2016-02-01

    Immobilization of enzymes enhances their properties for efficient utilization in industrial processes. Magnetic nanoparticles, due to their high surface area, large surface-to-volume ratio and easy separation under external magnetic fields, are highly valued. Significant progress has been made to develop new catalytic systems that are immobilized onto magnetic nanocarriers. This review provides an overview of recent developments in enzyme immobilization and stabilization protocols using this technology. The current applications of immobilized enzymes based on magnetic nanoparticles are summarized and future growth prospects are discussed. Recommendations are also given for areas of future research.

  15. Enhanced magnetic anisotropy in cobalt-carbide nanoparticles

    SciTech Connect

    El-Gendy, AA; Qian, MC; Huba, ZJ; Khanna, SN; Carpenter, EE

    2014-01-13

    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. (C) 2014 AIP Publishing LLC.

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

    PubMed

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

    2014-11-10

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

  17. Sequential repetitive chemical reduction technique to study size-property relationships of graphene attached Ag nanoparticle

    NASA Astrophysics Data System (ADS)

    Haider, M. Salman; Badejo, Abimbola Comfort; Shao, Godlisten N.; Imran, S. M.; Abbas, Nadir; Chai, Young Gyu; Hussain, Manwar; Kim, Hee Taik

    2015-06-01

    The present study demonstrates a novel, systematic and application route synthesis approach to develop size-property relationship and control the growth of silver nanoparticles (AgNPs) embedded on reduced graphene oxide (rGO). A sequential repetitive chemical reduction technique to observe the growth of silver nanoparticles (AgNPs) attached to rGO, was performed on a single solution of graphene oxide (GO) and silver nitrate solution (7 runs, R1-R7) in order to manipulate the growth and size of the AgNPs. The physical-chemical properties of the samples were examined by RAMAN, XPS, XRD, SEM-EDAX, and HRTEM analyses. It was confirmed that AgNPs with diameter varying from 4 nm in first run (R1) to 50 nm in seventh run (R7) can be obtained using this technique. A major correlation between particle size and activities was also observed. Antibacterial activities of the samples were carried out to investigate the disinfection performance of the samples on the Gram negative bacteria (Escherichia coli). It was suggested that the sample obtained in the third run (R3) exhibited the highest antibacterial activity as compared to other samples, toward disinfection of bacteria due to its superior properties. This study provides a unique and novel application route to synthesize and control size of AgNPs embedded on graphene for various applications.

  18. Nanoaperture optical tweezer with magnetic force characterization of magnetic nanoparticles (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Xu, Haitian; Jones, Steven; Choi, Byoung-Chul; Gordon, Reuven

    2016-09-01

    Double nanohole optical tweezers allow for trapping of nanoparticles down to single digit nanometer range, including individual proteins, viruses, DNA fragments and quantum dots. Here we demonstrate dual magnetic force / optical force analysis for the characterization of magnetic nanoparticles. From this single platform we can isolate individual nanoparticles and determine their size, permeability, remanence and permittivity. This is of interest for characterizing magnetic nanoparticles in mixtures, isolating ones of desired characteristics and pick-and-place assembly of magnetic nanoparticles in nanoscale magnetic devices. The magnetic nanoparticle is characterized by analysis of the optical transmission through a double-nanohole aperture with an applied magnetic gradient force. The optical transmission step at trapping, autocorrelation of transmission intensity, distribution of transmission values and variations with applied magnetic field amplitude provide information of individual magnetic nanoparticles that allows for determining their individual material characteristics. The values obtained agree well with past published values for iron oxide, and the size distribution over repeated measurements matches well with scanning electron microscope characterization (and manufacturer specifications).

  19. Preparation of silica coated cobalt ferrite magnetic nanoparticles for the purification of histidine-tagged proteins

    NASA Astrophysics Data System (ADS)

    Aygar, Gülfem; Kaya, Murat; Özkan, Necati; Kocabıyık, Semra; Volkan, Mürvet

    2015-12-01

    Surface modified cobalt ferrite (CoFe2O4) nanoparticles containing Ni-NTA affinity group were synthesized and used for the separation of histidine tag proteins from the complex matrices through the use of imidazole side chains of histidine molecules. Firstly, CoFe2O4 nanoparticles with a narrow size distribution were prepared in an aqueous solution using the controlled co-precipitation method. In order to obtain small CoFe2O4 agglomerates, oleic acid and sodium chloride were used as dispersants. The CoFe2O4 particles were coated with silica and subsequently the surface of these silica coated particles (SiO2-CoFe2O4) was modified by amine (NH2) groups in order to add further functional groups on the silica shell. Then, carboxyl (-COOH) functional groups were added to the SiO2-CoFe2O4 magnetic nanoparticles through the NH2 groups. After that Nα,Nα-Bis(carboxymethyl)-L-lysine hydrate (NTA) was attached to carboxyl ends of the structure. Finally, the surface modified nanoparticles were labeled with nickel (Ni) (II) ions. Furthermore, the modified SiO2-CoFe2O4 magnetic nanoparticles were utilized as a new system that allows purification of the N-terminal His-tagged recombinant small heat shock protein, Tpv-sHSP 14.3.

  20. Cobalt oxide magnetic nanoparticles-chitosan nanocomposite based electrochemical urea biosensor

    NASA Astrophysics Data System (ADS)

    Ali, A.; Israr-Qadir, M.; Wazir, Z.; Tufail, M.; Ibupoto, Z. H.; Jamil-Rana, S.; Atif, M.; Khan, S. A.; Willander, M.

    2015-04-01

    In this study, a potentiometric urea biosensor has been fabricated on glass filter paper through the immobilization of urease enzyme onto chitosan/cobalt oxide (CS/Co3O4) nanocomposite. A copper wire with diameter of 500 µm is attached with nanoparticles to extract the voltage output signal. The shape and dimensions of Co3O4 magnetic nanoparticles are investigated by scanning electron microscopy and the average diameter is approximately 80-100 nm. Structural quality of Co3O4 nanoparticles is confirmed from X-ray powder diffraction measurements, while the Raman spectroscopy has been used to understand the chemical bonding between different atoms. The magnetic measurement has confirmed that Co3O4 nanoparticles show ferromagnetic behavior, which could be attributed to the uncompensated surface spins and/or finite size effects. The ferromagnetic order of Co3O4 nanoparticles is raised with increasing the decomposition temperature. A physical adsorption method is adopted to immobilize the surface of CS/Co3O4 nanocomposite. Potentiometric sensitivity curve has been measured over the concentration range between 1 × 10-4 and 8 × 10-2 M of urea electrolyte solution revealing that the fabricated biosensor holds good sensing ability with a linear slope curve of 45 mV/decade. In addition, the presented biosensor shows good reusability, selectivity, reproducibility and resistance against interferers along with the stable output response of 12 s.

  1. Magnetic resonance in ferromagnetic films, multilayers and nanoparticle composites

    NASA Astrophysics Data System (ADS)

    Noginova, Natalia; Bates, Brittany; Greene, Nicole

    2014-03-01

    Incorporation of magnetic materials into metamaterial systems provides an opportunity to tune microwave permeability with external magnetic field. We studied magnetically dependent microwave properties of polymer composites with iron oxide nanoparticles, ferromagnetic films and ferromagnetic/dielectric multilayers. We show that the permeability of such systems can be magnetically tuned from positive to negative values in the range of ferromagnetic resonance, strongly affecting wave propagation. Strong changes in mu-metal permeability in low field range provides an additional possibility of tuning.

  2. 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 μm), 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

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

    NASA Astrophysics Data System (ADS)

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

    2011-04-01

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

  4. Amine-functionalized magnetic mesoporous silica nanoparticles for DNA separation

    NASA Astrophysics Data System (ADS)

    Sheng, Wei; Wei, Wei; Li, Junjian; Qi, Xiaoliang; Zuo, Gancheng; Chen, Qi; Pan, Xihao; Dong, Wei

    2016-11-01

    We report a modified approach for the functionalized magnetic mesoporous silica nanoparticles (MMSN) using polymer microspheres incorporated with magnetic nanoparticles in the presence of cetyltrimethylammonium bromide (CTAB) and the core-shell magnetic silica nanoparticles (MSN). These particles were functionalized with amino groups via the addition of aminosilane directly to the particle sol. We then evaluate their DNA separation abilities and find the capacity of DNA binding significantly increased (210.22 μg/mg) compared with normal magnetic silica spheres (138.44 μg/mg) by using an ultraviolet and visible spectrophotometer (UV). The morphologies, magnetic properties, particle size, pore size, core-shell structure and Zeta potential are characterized by Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), Transmission electron microscopy (TEM), Powder X-ray diffraction (XRD), and dynamic light scattering (DLS). This work demonstrates that our MMSN own an excellent potential application in bioseparation and drug delivery.

  5. The influence of the number and the type of magnetic attachment on the retention of mandibular mini implant overdenture

    PubMed Central

    2017-01-01

    PURPOSE The aim of this study was to compare the retention of mini implant overdenture by the number, the type of magnetic attachment, and the directions of applied dislodging force. MATERIALS AND METHODS The experimental groups were designed by the number and type of magnetic attachment. Twenty samples were tested with Magden implants. Each attachment was composed of the magnet assembly in overdenture sample and the abutment keeper in a mandibular model. Dislodging forces were applied to the overdenture samples (50.0 mm/min) in 3 directions. The loading was repeated 10 times in each direction. The values of dislodging force were analyzed statistically using SPSS at 95% level of confidence. RESULTS The retentive force of group 2 was greater than that of group 1 in both types of attachment in every direction (P < .05). Oblique retentive force of flat type magnetic attachment was higher than that of cushion type attachment in both groups (P < .05). In group 1, oblique retentive force showed the highest and anterior-posterior retentive force showed the lowest value in both attachment types (P < .05). In group 2, both types of attachment showed the lowest retentive force with anteriorposterior direction of dislodging force (P <.05). CONCLUSION Proper retentive properties for implant overdenture were obtained, regardless of the number and type of magnetic attachment. In both types of magnetic attachment, the greater retentive force was attained with more implants. Oblique retentive force of flat type magnetic attachment was greater than that of cushion type. Among all subgroups, anterior-posterior retentive force was the lowest among three different directions of dislodging force. PMID:28243387

  6. Magnetic Properties of Fe Oxide Nanoparticles Produced by Laser Pyrolysis for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    García, M. A.; Bouzas, V.; Costo, R.; Veintemillas, S.; Morales, P.; García-Hernández, M.; Alexandrescu, R.; Morjan, I.; Gasco, P.

    2010-10-01

    We report on the magnetic characterization of Fe oxide nanoparticles by laser pyrolysis and the relationship between the preparation conditions and the magnetic response. It is shown that controlling the preparation conditions during the pyrolisis allows tuning the nanoparticles morphology and structure and consequently the magnetic properties of the nanoparticles. The nanoparticles are loaded into solid lipid nanoparticles without degradation nor significant modification of the magnetic properties.

  7. 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.

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

    PubMed

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

    2013-09-11

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

  9. Design of Superparamagnetic Nanoparticles for Magnetic Particle Imaging (MPI)

    PubMed Central

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

    2013-01-01

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

  10. 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.

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

    PubMed

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

    2013-12-04

    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.

  12. Fabrication and characterization of magnetic nanoparticle composite membranes

    NASA Astrophysics Data System (ADS)

    Cruickshank, Akeem Armand

    To effectively and accurately deliver drugs within the human body, both new designs and components for implantable micropumps are being studied. Designs must ensure high biocompatibility, drug compatibility, accuracy and small power consumption. The focus of this thesis was to fabricate a prototype magnetic nanoparticle membrane for eventual incorporation into a biomedical pump and then determine the relationship between this membrane deflection and applied pneumatic or magnetic force. The magnetic nanoparticle polymer composite (MNPC) membranes in this study were composed of crosslinked polydimethylsiloxane (PDMS) and iron oxide nanoparticles (IONPs). An optimal iron oxide fabrication route was identified and particle size in each batch was approximately 24.6 nm. Once these nanoparticles were incorporated into a membrane (5 wt. %), the nanoparticle formed agglomerates with an average diameter of 2.26 +/-1.23 microm. Comparisons between the 0 and 5 wt. % loading of particles into the membranes indicated that the elastic modulus of the composite decreased with increasing particle concentration. The pressure- central deflection of the membranes could not be predicated by prior models and variation between magnetic and pneumatic pressure-deflection curves was quantified. Attempts to fabricate membranes with above 5 wt. % nanoparticles were not successful (no gelation). Fourier Transform Infrared (FTIR) spectroscopy results suggest that excess oleic acid on the nanoparticles prior to mixing might have prevented crosslinking.

  13. Magnetic nanoparticles for medical applications: Progress and challenges

    NASA Astrophysics Data System (ADS)

    Doaga, A.; Cojocariu, A. M.; Constantin, C. P.; Hempelmann, R.; Caltun, O. F.

    2013-11-01

    Magnetic nanoparticles present unique properties that make them suitable for applications in biomedical field such as magnetic resonance imaging (MRI), hyperthermia and drug delivery systems. Magnetic hyperthermia involves heating the cancer cells by using magnetic particles exposed to an alternating magnetic field. The cell temperature increases due to the thermal propagation of the heat induced by the nanoparticles into the affected region. In order to increase the effectiveness of the treatment hyperthermia can be combined with drug delivery techniques. As a spectroscopic technique MRI is used in medicine for the imaging of tissues especially the soft ones and diagnosing malignant or benign tumors. For this purpose ZnxCo1-xFe2O4 ferrite nanoparticles with x between 0 and 1 have been prepared by co-precipitation method. The cristallite size was determined by X-ray diffraction, while the transmission electron microscopy illustrates the spherical shape of the nanoparticles. Magnetic characterizations of the nanoparticles were carried out at room temperature by using a vibrating sample magnetometer. The specific absorption rate (SAR) was measured by calorimetric method at different frequencies and it has been observed that this value depends on the chemical formula, the applied magnetic fields and the frequency. The study consists of evaluating the images, obtained from an MRI facility, when the nanoparticles are dispersed in agar phantoms compared with the enhanced ones when Omniscan was used as contrast agent. Layer-by-layer technique was used to achieve the necessary requirement of biocompatibility. The surface of the magnetic nanoparticles was modified by coating it with oppositely charged polyelectrolites, making it possible for the binding of a specific drug.

  14. Magnetic nanoparticles for medical applications: Progress and challenges

    SciTech Connect

    Doaga, A.; Cojocariu, A. M.; Constantin, C. P.; Caltun, O. F.; Hempelmann, R.

    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.

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

    SciTech Connect

    Picraux, Samuel T; Manandhar, Pradeep; Nazaretski, E; Thompson, J

    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.

  16. Neural correlates of attachment trauma in borderline personality disorder: a functional magnetic resonance imaging study.

    PubMed

    Buchheim, Anna; Erk, Susanne; George, Carol; Kächele, Horst; Kircher, Tilo; Martius, Philipp; Pokorny, Dan; Ruchsow, Martin; Spitzer, Manfred; Walter, Henrik

    2008-08-30

    Functional imaging studies have shown that individuals with borderline personality disorder (BPD) display prefrontal and amygdala dysfunction while viewing or listening to emotional or traumatic stimuli. The study examined for the first time the functional neuroanatomy of attachment trauma in BPD patients using functional magnetic resonance imaging (fMRI) during the telling of individual stories. A group of 11 female BPD patients and 17 healthy female controls, matched for age and education, told stories in response to a validated set of seven attachment pictures while being scanned. Group differences in narrative and neural responses to "monadic" pictures (characters facing attachment threats alone) and "dyadic" pictures (interaction between characters in an attachment context) were analyzed. Behavioral narrative data showed that monadic pictures were significantly more traumatic for BPD patients than for controls. As hypothesized BPD patients showed significantly more anterior midcingulate cortex activation in response to monadic pictures than controls. In response to dyadic pictures patients showed more activation of the right superior temporal sulcus and less activation of the right parahippocampal gyrus compared to controls. Our results suggest evidence for potential neural mechanisms of attachment trauma underlying interpersonal symptoms of BPD, i.e. fearful and painful intolerance of aloneness, hypersensitivity to social environment, and reduced positive memories of dyadic interactions.

  17. Magnetoelectric Effect and Magnetodielectric Effect in Magnetic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kim, Hyungsuk

    Nano-sized magnetic particles represent considerable interests in modern science because their properties are advantageous to applications such as data storage and medical science. In particular, superparamagnetism is a magnetic property which is found in nano-sized (approximately less than 20 nm) ferromagnetic or ferrimagnetic particles. Studies have shown that superparamagnetic material shows ferromagnetic magnetization only with an external magnetic field; without an external magnetic field, it loses magnetic properties even at ambient temperature overcoming its intrinsic anisotropy energy. From a magnetic memory standpoint, as bit size decreases, superparamagnetism is a major obstacle to thermal stability due to this volatility, resulting in a loss of information. If it is possible to modulate the superparamagnetic properties of magnetic nanoparticles, this might provide a solution to this critical issue. In this dissertation, we studied the modulation of superparamagnetic properties by applying an electric field on a magnetoelectric composite composed of magnetic nanoparticles and a piezoelectric substrate. The magnetoelectric effect might present an additional solution to memory device in terms of reducing writing energy by using an electric field rather than an electric current. Additionally, for systems lacking a significant magnetoelectric coupling (for instance, magnetic nanoparticles incased in polymer resin), the relationship between the dielectric constant, which is intrinsically related to ferroelectric order, and magnetic anisotropy energy was investigated.

  18. Magnetic Composite Thin Films of Fe xO y Nanoparticles and Photocrosslinked Dextran Hydrogels

    NASA Astrophysics Data System (ADS)

    Brunsen, Annette; Utech, Stefanie; Maskos, Michael; Knoll, Wolfgang; Jonas, Ulrich

    2012-04-01

    Magnetic hydrogel composites are promising candidates for a broad field of applications from medicine to mechanical engineering. Here, surface-attached composite films of magnetic nanoparticles (MNP) and a polymeric hydrogel (HG) were prepared from magnetic iron oxide nanoparticles and a carboxymethylated dextran with photoreactive benzophenone substituents. A blend of the MNP and the dextran polymer was prepared by mixing in solution, and after spin-coating and drying the blend film was converted into a stable MNP-HG composite by photocrosslinking through irradiation with UV light. The bulk composite material shows strong mobility in a magnetic field, imparted by the MNPs. By utilizing a surface layer of a photoreactive adhesion promoter on the substrates, the MNP-HG films were covalently immobilized during photocrosslinking. The high stability of the composite was documented by rinsing experiments with UV-Vis spectroscopy, while surface plasmon resonance and optical waveguide mode spectroscopy was employed to investigate the swelling behavior in dependence of the nanoparticle concentration, the particle type, and salt concentration.

  19. Spatiotemporal control of microtubule nucleation and assembly using magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  20. Sensing gyroscopic properties of rotating magnetic nanoparticles in solution

    NASA Astrophysics Data System (ADS)

    Krug, Brian Gerald

    A new sensor using magnetic nanoparticles and rotating magnetic fields has been developed. By spinning the nanoparticles in a rotating magnetic field, it is feasible to infer angular position and inertia if an external force is applied to the system. The nanoparticles are treated as a multitude of miniature gyroscopes whose overall effect can be combined as one single gyroscope. Two sensors were built to test the feasibility, both containing Fe3O4 nanoparticles. The typical input current was 250 milliamps. When the sensor deviated from its magnetic axis by a small angle, the input current changed between 1 and 2 milliamps from the maximum input current Nanoparticles immersed in water had a more dramatic response than those suspended in toluene. The response was not completely predictable as some interactions during a disturbance were not accounted for. The sensor was effective if the angle changes are at 100 Hz or slower frequencies. When the sensor was returned to its original starting state at the end of a test, the output did not always return to the starting state output. This was attributed to not driving the magnetic nanoparticles hard enough into saturation. The proposed sensor design is simple to construct, easy to control, and its position is easy to obtain. The output is predictable and has a relatively useful bandwidth for most portable applications. It has environmental limitations and low signal constraints, but both can be overcome with better materials and filtering techniques.

  1. Photodegradation of Eosin Y Using Silver-Doped Magnetic Nanoparticles

    PubMed Central

    Alzahrani, Eman

    2015-01-01

    The purification of industrial wastewater from dyes is becoming increasingly important since they are toxic or carcinogenic to human beings. Nanomaterials have been receiving significant attention due to their unique physical and chemical properties compared with their larger-size counterparts. The aim of the present investigation was to fabricate magnetic nanoparticles (MNPs) using a coprecipitation method, followed by coating with silver (Ag) in order to enhance the photocatalytic activity of the MNPs by loading metal onto them. The fabricated magnetic nanoparticles coated with Ag were characterised using different instruments such as a scanning electron microscope (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDAX) spectroscopy, and X-ray diffraction (XRD) analysis. The average size of the magnetic nanoparticles had a mean diameter of about 48 nm, and the average particle size changed to 55 nm after doping. The fabricated Ag-doped magnetic nanoparticles were used for the degradation of eosin Y under UV-lamp irradiation. The experimental results revealed that the use of fabricated magnetic nanoparticles coated with Ag can be considered as reliable methods for the removal of eosin Y since the slope of evaluation of pseudo-first-order rate constant from the slope of the plot between ln⁡(Co/C) and the irradiation time was found to be linear. Ag-Fe3O4 nanoparticles would be considered an efficient photocatalyst to degrade textile dyes avoiding the tedious filtration step. PMID:26617638

  2. Magnetically responsive nanoparticles for drug delivery applications using low magnetic field strengths.

    PubMed

    McGill, Shayna L; Cuylear, Carla L; Adolphi, Natalie L; Osiński, Marek; Smyth, Hugh D C

    2009-03-01

    The purpose of this study is to investigate the potential of magnetic nanoparticles for enhancing drug delivery using a low oscillating magnetic field (OMF) strength. We investigated the ability of magnetic nanoparticles to cause disruption of a viscous biopolymer barrier to drug delivery and the potential to induce triggered release of drug conjugated to the surfaces of these particles. Various magnetic nanoparticles were screened for thermal response under a 295-kHz OMF with an amplitude of 3.1 kA/m. Based on thermal activity of particles screened, we selected the nanoparticles that displayed desired characteristics for evaluation in a simplified model of an extracellular barrier to drug delivery, using lambda DNA/HindIII. Results indicate that nanoparticles could be used to induce DNA breakage to enhance local diffusion of drugs, despite low temperatures of heating. Additional studies showed increased diffusion of quantum dots in this model by single-particle tracking methods. Bimane was conjugated to the surface of magnetic nanoparticles. Fluorescence and transmission electron microscope images of the conjugated nanoparticles indicated little change in the overall appearance of the nanoparticles. A release study showed greater drug release using OMF, while maintaining low bulk heating of the samples (T = 30 degrees C). This study indicates that lower magnetic field strengths may be successfully utilized for drug delivery applications as a method for drug delivery transport enhancement and drug release switches.

  3. Probing magnetic and gold nanoparticles by using MAClevers® as ultrasensitive sensors.

    PubMed

    Nakamura, Marcelo; Araki, Koiti; Toma, Henrique E

    2010-12-01

    Magnetic AFM probes known as MAClevers® were employed for sensing picogram amounts of magnetic nanoparticles, based on the cantilever frequency shifts resulting from the magnetically induced adsorption of mass. By using organothiol functionalized magnetic nanoparticles, this analytical strategy was successfully extended to the detection of gold nanoparticles, as confirmed by confocal Raman microscopy.

  4. Magnetic properties of heat treated bacterial ferrihydrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Balaev, D. A.; Krasikov, A. A.; Dubrovskiy, A. A.; Popkov, S. I.; Stolyar, S. V.; Bayukov, O. A.; Iskhakov, R. S.; Ladygina, V. P.; Yaroslavtsev, R. N.

    2016-07-01

    The magnetic properties of ferrihydrite nanoparticles, which are products of vital functions of Klebsiella oxitoca bacteria, have been studied. The initial powder containing the nanoparticles in an organic shell was subjected to low-temperature (T=160 °C) heat treatment for up to 240 h. The bacterial ferrihydrite particles exhibit a superparamagnetic behavior. Their characteristic blocking temperature increases from 26 to 80 K with the heat treatment. Analysis of the magnetization curves with regard to the magnetic moment distribution function and antiferromagnetic contribution shows that the low-temperature heat treatment enhances the average magnetic moment of a particle; i.e., the nanoparticles coarsen, probably due to their partial agglomeration during heat treatment. It was established that the blocking temperature nonlinearly depends on the particle volume. Therefore, a model was proposed that takes into account both the bulk and surface magnetic anisotropy. Using this model, the bulk and surface magnetic anisotropy constants KV≈1.7×105 erg/cm3 and KS≈0.055 erg/cm2 have been determined. The effect of the surface magnetic anisotropy of ferrihydrite nanoparticles on the observed magnetic hysteresis loops is discussed.

  5. Synthesis and Magnetic Properties of CoPt Nanoparticles

    NASA Astrophysics Data System (ADS)

    Trung, Truong Thanh; Nhung, Do Thi; Nam, Nguyen Hoang; Luong, Nguyen Hoang

    2016-07-01

    Magnetic nanoparticles CoPt were prepared by the chemical reduction of cobalt (II) chloride and chloroplatinic acid, then the samples were ultrasonicated for 2 h. After annealing at various temperatures from 400°C to 700°C for 1 h, the samples showed hard magnetic properties with coercivity up to 1.15 kOe at room temperature.

  6. Mathematical modelling for trajectories of magnetic nanoparticles in a blood vessel under magnetic field

    NASA Astrophysics Data System (ADS)

    Sharma, Shashi; Katiyar, V. K.; Singh, Uaday

    2015-04-01

    A mathematical model is developed to describe the trajectories of a cluster of magnetic nanoparticles in a blood vessel for the application of magnetic drug targeting (MDT). The magnetic nanoparticles are injected into a blood vessel upstream from a malignant tissue and are captured at the tumour site with help of an applied magnetic field. The applied field is produced by a rare earth cylindrical magnet positioned outside the body. All forces expected to significantly affect the transport of nanoparticles were incorporated, including magnetization force, drag force and buoyancy force. The results show that particles are slow down and captured under the influence of magnetic force, which is responsible to attract the magnetic particles towards the magnet. It is optimized that all particles are captured either before or at the centre of the magnet (z≤0) when blood vessel is very close proximity to the magnet (d=2.5 cm). However, as the distance between blood vessel and magnet (d) increases (above 4.5 cm), the magnetic nanoparticles particles become free and they flow away down the blood vessel. Further, the present model results are validated by the simulations performed using the finite element based COMSOL software.

  7. Microfluidic separation of magnetic nanoparticles on an ordered array of magnetized micropillars

    NASA Astrophysics Data System (ADS)

    Orlandi, G.; Kuzhir, P.; Izmaylov, Y.; Alves Marins, J.; Ezzaier, H.; Robert, L.; Doutre, F.; Noblin, X.; Lomenech, C.; Bossis, G.; Meunier, A.; Sandoz, G.; Zubarev, A.

    2016-06-01

    Microfluidic separation of magnetic particles is based on their capture by magnetized microcollectors while the suspending fluid flows past the microcollectors inside a microchannel. Separation of nanoparticles is often challenging because of strong Brownian motion. Low capture efficiency of nanoparticles limits their applications in bioanalysis. However, at some conditions, magnetic nanoparticles may undergo field-induced aggregation that amplifies the magnetic attractive force proportionally to the aggregate volume and considerably increases nanoparticle capture efficiency. In this paper, we have demonstrated the role of such aggregation on an efficient capture of magnetic nanoparticles (about 80 nm in diameter) in a microfluidic channel equipped with a nickel micropillar array. This array was magnetized by an external uniform magnetic field, of intensity as low as 6-10 kA/m, and experiments were carried out at flow rates ranging between 0.3 and 30 μ L /min . Nanoparticle capture is shown to be mostly governed by the Mason number Ma, while the dipolar coupling parameter α does not exhibit a clear effect in the studied range, 1.4 < α < 4.5. The capture efficiency Λ shows a strongly decreasing Mason number behavior, Λ ∝M a-1.78 within the range 32 ≤ Ma ≤ 3250. We have proposed a simple theoretical model which considers destructible nanoparticle chains and gives the scaling behavior, Λ ∝M a-1.7 , close to the experimental findings.

  8. Microfluidic separation of magnetic nanoparticles on an ordered array of magnetized micropillars.

    PubMed

    Orlandi, G; Kuzhir, P; Izmaylov, Y; Alves Marins, J; Ezzaier, H; Robert, L; Doutre, F; Noblin, X; Lomenech, C; Bossis, G; Meunier, A; Sandoz, G; Zubarev, A

    2016-06-01

    Microfluidic separation of magnetic particles is based on their capture by magnetized microcollectors while the suspending fluid flows past the microcollectors inside a microchannel. Separation of nanoparticles is often challenging because of strong Brownian motion. Low capture efficiency of nanoparticles limits their applications in bioanalysis. However, at some conditions, magnetic nanoparticles may undergo field-induced aggregation that amplifies the magnetic attractive force proportionally to the aggregate volume and considerably increases nanoparticle capture efficiency. In this paper, we have demonstrated the role of such aggregation on an efficient capture of magnetic nanoparticles (about 80 nm in diameter) in a microfluidic channel equipped with a nickel micropillar array. This array was magnetized by an external uniform magnetic field, of intensity as low as 6-10 kA/m, and experiments were carried out at flow rates ranging between 0.3 and 30 μL/min. Nanoparticle capture is shown to be mostly governed by the Mason number Ma, while the dipolar coupling parameter α does not exhibit a clear effect in the studied range, 1.4 < α < 4.5. The capture efficiency Λ shows a strongly decreasing Mason number behavior, Λ∝Ma^{-1.78} within the range 32 ≤ Ma ≤ 3250. We have proposed a simple theoretical model which considers destructible nanoparticle chains and gives the scaling behavior, Λ∝Ma^{-1.7}, close to the experimental findings.

  9. Nonequilibrium magnetic response of anisotropic superparamagnetic nanoparticles and possible artifacts in magnetic particle imaging.

    PubMed

    Mamiya, Hiroaki; Jeyadevan, Balachandran

    2015-01-01

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

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

    PubMed Central

    Mamiya, Hiroaki; Jeyadevan, Balachandran

    2015-01-01

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

  11. 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.

  12. A magnonic gas sensor based on magnetic nanoparticles.

    PubMed

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

    2015-06-07

    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.

  13. Magnetic nanoparticles coated with polyaniline to stabilize immobilized trypsin

    NASA Astrophysics Data System (ADS)

    Maciel, J. C.; D. Mercês, A. A.; Cabrera, M.; Shigeyosi, W. T.; de Souza, S. D.; Olzon-Dionysio, M.; Fabris, J. D.; Cardoso, C. A.; Neri, D. F. M.; C. Silva, M. P.; Carvalho, L. B.

    2016-12-01

    It is reported the synthesis of magnetic nanoparticles via the chemical co-precipitation of Fe 3+ ions and their preparation by coating them with polyaniline. The electronic micrograph analysis showed that the mean diameter for the nanoparticles is ˜15 nm. FTIR, powder X-ray diffraction and Mössbauer spectroscopy were used to understand the chemical, crystallographic and 57Fe hyperfine structures for the two samples. The nanoparticles, which exhibited magnetic behavior with relatively high spontaneous magnetization at room temperature, were identified as being mainly formed by maghemite ( γFe2O3). The coated magnetic nanoparticles (sample labeled "mPANI") presented a real ability to bind biological molecules such as trypsin, forming the magnetic enzyme derivative (sample "mPANIG-Trypsin"). The amount of protein and specific activity of the immobilized trypsin were found to be 13±5 μg of protein/mg of mPANI (49.3 % of immobilized protein) and 24.1±0.7 U/mg of immobilized protein, respectively. After 48 days of storage at 4 ∘C, the activity of the immobilized trypsin was found to be 89 % of its initial activity. This simple, fast and low-cost procedure was revealed to be a promising way to prepare mPANI nanoparticles if technological applications addressed to covalently link biomolecules are envisaged. This route yields chemically stable derivatives, which can be easily recovered from the reaction mixture with a magnetic field and recyclable reused.

  14. The Colloidal Stability of Magnetic Nanoparticles in Ionic Liquids

    DTIC Science & Technology

    2015-08-03

    Final 3. DATES COVERED (From - To) 14 May 2014 – 13 May 2015 4. TITLE AND SUBTITLE The Colloidal Stability of Magnetic Nanoparticles in...DATE 11 SEP 2015 2. REPORT TYPE Final 3. DATES COVERED 14-05-2014 to 13-05-2015 4. TITLE AND SUBTITLE The Colloidal Stability of Magnetic...Rev. 8-98) Prescribed by ANSI Std Z39-18 Final Report for AOARD Grant 144062 “The Colloidal Stability of Magnetic Nanoparticles in Ionic Liquids

  15. Dynamic analysis of magnetic nanoparticles crossing cell membrane

    NASA Astrophysics Data System (ADS)

    Pedram, Maysam Z.; Shamloo, Amir; Ghafar-Zadeh, Ebrahim; Alasty, Aria

    2017-01-01

    Nowadays, nanoparticles (NPs) are used in a variety of biomedical applications including brain disease diagnostics and subsequent treatments. Among the various types of NPs, magnetic nanoparticles (MNPs) have been implemented by many research groups for an array of life science applications. In this paper, we studied MNPs controlled delivery into the endothelial cells using a magnetic field. Dynamics equations of MNPs were defined in the continuous domain using control theory methods and were applied to crossing the cell membrane. This study, dedicated to clinical and biomedical research applications, offers a guideline for the generation of a magnetic field required for the delivery of MNPs.

  16. Enhancement in magnetic properties of magnesium substituted bismuth ferrite nanoparticles

    SciTech Connect

    Xu, Jianlong; Xie, Dan E-mail: RenTL@mail.tsinghua.edu.cn; Teng, Changjiu; Zhang, Xiaowen; Zhang, Cheng; Sun, Yilin; Ren, Tian-Ling E-mail: RenTL@mail.tsinghua.edu.cn; Zeng, Min; Gao, Xingsen; Zhao, Yonggang

    2015-06-14

    We report a potential way to effectively improve the magnetic properties of BiFeO{sub 3} (BFO) nanoparticles through Mg{sup 2+} ion substitution at the Fe-sites of BFO lattice. The high purity and structural changes induced by Mg doping are confirmed by X-ray powder diffractometer and Raman spectra. Enhanced magnetic properties are observed in Mg substituted samples, which simultaneously exhibit ferromagnetic and superparamagnetic properties at room temperature. A physical model is proposed to support the observed ferromagnetism of Mg doped samples, and the superparamagnetic properties are revealed by the temperature dependent magnetization measurements. The improved magnetic properties and soft nature obtained by Mg doping in BFO nanoparticles demonstrate the possibility of BFO nanoparticles to practical applications.

  17. Enhancement in magnetic properties of magnesium substituted bismuth ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Xu, Jianlong; Xie, Dan; Teng, Changjiu; Zhang, Xiaowen; Zhang, Cheng; Sun, Yilin; Ren, Tian-Ling; Zeng, Min; Gao, Xingsen; Zhao, Yonggang

    2015-06-01

    We report a potential way to effectively improve the magnetic properties of BiFeO3 (BFO) nanoparticles through Mg2+ ion substitution at the Fe-sites of BFO lattice. The high purity and structural changes induced by Mg doping are confirmed by X-ray powder diffractometer and Raman spectra. Enhanced magnetic properties are observed in Mg substituted samples, which simultaneously exhibit ferromagnetic and superparamagnetic properties at room temperature. A physical model is proposed to support the observed ferromagnetism of Mg doped samples, and the superparamagnetic properties are revealed by the temperature dependent magnetization measurements. The improved magnetic properties and soft nature obtained by Mg doping in BFO nanoparticles demonstrate the possibility of BFO nanoparticles to practical applications.

  18. Magnetic domains and surface effects in hollow maghemite nanoparticles

    SciTech Connect

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

    2008-09-30

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

  19. 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

  20. Measuring Cytokine Concentrations Using Magnetic Spectroscopy of Nanoparticle Brownian Relaxation

    NASA Astrophysics Data System (ADS)

    Khurshid, Hafsa; Shi, Yipeng; Weaver, John

    The magnetic particle spectroscopy is a newly developed non-invasive technique for obtaining information about the nanoparticles' micro environment. In this technique the nanoparticles' magnetization, induced by an alternating magnetic field at various applied frequencies, is processed to analyze rotational freedom of nanoparticles. By analyzing average rotational freedom, it is possible to measure the nanoparticle's relaxation time, and hence get an estimate of the temperature and viscosity of the medium. In molecular concentration sensing, the rotational freedom indicates the number of nanoparticles that are bound by a selected analyte. We have developed microscopic nanoparticles probes to measure the concentration of selected molecules. The nanoparticles are targeted to bind the selected molecule and the resulting reduction in rotational freedom can be quantified remotely. Previously, sensitivity measurements has been reported to be of the factor of 200. However, with our newer perpendicular field setup (US Patent Application Serial No 61/721,378), it possible to sense cytokine concentrations as low as 5 Pico-Molar in-vitro. The excellent sensitivity of this apparatus is due to isolation of the drive field from the signal so the output can be amplified to a higher level. Dartmouth College.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  3. [Assemble of magnetic nanoparticles into the structure of cisplatin liposome].

    PubMed

    Wang, Lu; Yang, Cai-qin; Wang, Jing

    2011-05-01

    Effects of different procedures of magnetic nanoparticles into the liposome structure on the distribution of magnetic particles in the liposome were investigated. Magnetic liposomes with high-encapsulating rate of cisplatin (CDDP) were obtained. Fe3O4 magnetic nanoparticles which was modified by organic functional group on surface was synthesized by an one-step modified hydrothermal method. The CDDP magnetic liposomes were prepared by a film scattering-ultrasonic technique and the concentrations of CDDP in the liposomes were measured by graphite furnace atomic absorbance spectroscopy. Magnetic liposomes with different microstructure were prepared by the two different procedures, where the magnetic particles were combined with phospholipid before the film preparation to form liposome in procedure I, and drug solution and the magnetic particles were mixed before hydrating the lipids film to form liposome in procedure II. The liposome structure was observed by transmission electron microscope (TEM). The CDDP magnetic liposomes were prepared by the optimized method which was selected by orthogonal test. Encapsulation rate of the magnetic particles distributed in the phospholipid bilayer through the procedure I was 34.90%. While liposome, produced by the procedure II technique, contained magnetic particles in the interior aqueous compartment, which encapsulation rate was 28.34%. Encapsulation rates of both I and II were higher than that of conventional liposome. The release profile of all the three different liposomes in vitro fitted with a first-order equation. Because of distribution of magnetic particles in the phospholipid bilayer, the skeleton of phospholipid bilayer was changed. The releasing tl/2 of magnetic liposomes produced by the procedure I technique is 9 h, which is shorter than that of the other two liposomes. Assemble of magnetic nanoparticles into the structure of liposome was succeeded by the procedure I, which showed superiority than by procedure II

  4. Enhanced drug transport through alginate biofilms using magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

  5. Tailoring magnetic PLGA nanoparticles suitable for doxorubicin delivery

    NASA Astrophysics Data System (ADS)

    Tansık, Gülistan; Yakar, Arzu; Gündüz, Ufuk

    2014-01-01

    One of the main problems of current cancer chemotherapy is the lack of selectivity of anti-cancer drugs to tumor cells, which leads to systemic toxicity and adverse side effects. In order to overcome these limitations, researches on controlled drug delivery systems have gained much attention. Nanoscale-based drug delivery systems provide tumor targeting. Among many types of nanocarriers, superparamagnetic nanoparticles with their biocompatible polymer coatings can be targeted to an intented site by an external magnetic field. Thus, the drug can be carried to the targeted site safely. The aim of this study is to prepare poly( dl-lactic- co-glycolic acid) (PLGA)-coated magnetic nanoparticles and load anti-cancer drug, doxorubicin to them. For this purpose, magnetite (Fe3O4) iron oxide nanoparticles were synthesized as a magnetic core material (MNP) and then coated with oleic acid. Oleic acid-coated MNP (OA-MNP) was encapsulated into PLGA. Effects of different OA-MNP/PLGA ratios on magnetite entrapment efficiency were investigated. Doxorubicin-loaded magnetic polymeric nanoparticles (DOX-PLGA-MNP) were prepared. After the characterization of prepared nanoparticles, their cytotoxic effects on MCF-7 cell line were studied. PLGA-coated magnetic nanoparticles (PLGA-MNP) had a proper size and superparamagnetic character. The highest magnetite entrapment efficiency of PLGA-MNP was estimated as 63 % at 1:8 ratio. Cytotoxicity studies of PLGA-MNP did not indicate any notable cell death between the concentration ranges of 2 and 125 μg/ml. Drug loading efficiency was estimated as 32 %, and it was observed that DOX-PLGA-MNP showed significant cytotoxicity on MCF-7 cells compared to PLGA-MNP. The results showed that prepared nanoparticles have desired size and superparamagnetic characteristics without serious toxic effects on cells. These nanoparticles may be suitable for targeted drug delivery applications.

  6. Silica-coated nanocomposites of magnetic nanoparticles and quantum dots.

    PubMed

    Yi, Dong Kee; Selvan, S Tamil; Lee, Su Seong; Papaefthymiou, Georgia C; Kundaliya, Darshan; Ying, Jackie Y

    2005-04-13

    Quantum dots (QDs) and magnetic nanoparticles (MPs) are of interest for biological imaging, drug targeting, and bioconjugation because of their unique optoelectronic and magnetic properties, respectively. To provide for water solubility and biocompatibility, QDs and MPs were encapsulated within a silica shell using a reverse microemulsion synthesis. The resulting SiO2/MP-QD nanocomposite particles present a unique combination of magnetic and optical properties. Their nonporous silica shell allows them to be surface modified for bioconjugation in various biomedical applications.

  7. A Two-Magnet System to Push Therapeutic Nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    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.

  8. A Two-Magnet System to Push Therapeutic Nanoparticles.

    PubMed

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

    2010-12-01

    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.

  9. 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

  10. Magnetic relaxation in a suspension of antiferromagnetic nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2008-09-01

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

  11. Progress in applications of magnetic nanoparticles in biomedicine

    NASA Astrophysics Data System (ADS)

    Pankhurst, Q. A.; Thanh, N. T. K.; Jones, S. K.; Dobson, J.

    2009-11-01

    A progress report is presented on a selection of scientific, technological and commercial advances in the biomedical applications of magnetic nanoparticles since 2003. Particular attention is paid to (i) magnetic actuation for in vitro non-viral transfection and tissue engineering and in vivo drug delivery and gene therapy, (ii) recent clinical results for magnetic hyperthermia treatments of brain and prostate cancer via direct injection, and continuing efforts to develop new agents suitable for targeted hyperthermia following intravenous injection and (iii) developments in medical sensing technologies involving a new generation of magnetic resonance imaging contrast agents, and the invention of magnetic particle imaging as a new modality. Ongoing prospects are also discussed.

  12. A portable Hall magnetometer probe for characterization of magnetic iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Araujo, Jefferson F. D. F.; Costa, Mateus C.; Louro, Sonia R. W.; Bruno, Antonio C.

    2017-03-01

    We have built a portable Hall magnetometer probe, for measuring magnetic properties of iron oxide nanoparticles, that can be used for bulk materials and liquid samples as well. The magnetometer probe consists of four voltage-programmable commercial Hall sensors and a thin acrylic plate for positioning the sensors. In order to operate, it needs to be attached to a pole of an electromagnet and connected to an AD converter and a computer. It acquires a complete magnetization curve in a couple of minutes and has a magnetic moment sensitivity of 3.5×10-7 Am2. We tested its performance with magnetic nanoparticles containing an iron oxide core and having coating layers with different sizes. The magnetization results obtained were compared with measurements performed on commercial stand-alone magnetometers, and exhibited errors of about ±0.2 Am2/kg (i.e 0.4%) at saturation and below 0.5 Am2/kg (i.e. 10%) at remanence.

  13. Cobalt-based Magnetic Nanoparticles: Design, Synthesis and Characterization

    NASA Astrophysics Data System (ADS)

    Zamanpour, Mehdi

    The ever-increasing desire for more energy attainable from a smaller volume of matter has driven researchers to explore advanced materials at the molecular or even atomic size scale. Magnetic materials at the nanometer size scale have been the subject of enormous research effort worldwide for more than half a century. Different magnetic nanoparticles have shown different behavior in the absence and presence of an external magnetic field, which has led them to be categorized as soft (easy to demagnetize) or hard (resistive against demagnetization) magnets. Applications range from medical and biomedical devices to magnetic recording media and magnetic sensing have emphasized the importance of this class of materials. Soft magnetic phases have found application in power generation and magnetic targeted drug delivery, while hard magnets have been subject of extensive research for application as energy storage media. Discovery of the exchange-coupling phenomenon between the spins of two adjacent hard and soft magnetic phases which means taking advantage of both high magnetic moment of the soft phase as well as high coercivity of the hard phase has attracted scientists to develop advanced materials for energy storage with no usage of fossil fuels: clean energy. In this Dissertation, synthesis of pure phase, soft FeCo nanoparticles with high magnetic moment and hard phase CoxC nanoparticles possessing high coercivity is reported. The polyol method (chemical co-precipitating at polyhydric alcohol as reducing agent) is used to make FeCo and Co xC nanoparticles and the effects of important reaction kinetics parameters on the structure and magnetic properties of the products are studied. Careful analysis of correlations between these parameters and the properties of the magnetic particles has made synthesis of FeCo and CoxC nanoparticles with desired properties possible. Fabrication of MnAlC-FeCo heterostructures as a rare earth-free alternative for high-performance permanent

  14. Waved albatrosses can navigate with strong magnets attached to their head.

    PubMed

    Mouritsen, Henrik; Huyvaert, Kathryn P; Frost, Barrie J; Anderson, David J

    2003-11-01

    The foraging excursions of waved albatrosses Phoebastria irrorata during incubation are ideally suited for navigational studies because they navigate between their Galápagos breeding site and one specific foraging site in the upwelling zone of Peru along highly predictable, straight-line routes. We used satellite telemetry to follow free-flying albatrosses after manipulating magnetic orientation cues by attaching magnets to strategic places on the birds' heads. All experimental, sham-manipulated and control birds, were able to navigate back and forth from Galápagos to their normal foraging sites at the Peruvian coast over 1000 km away. Birds subjected to the three treatments did not differ in the routes flown or in the duration and speed of the trips. The interpretations and implications of this result depend on which of the current suggested magnetic sensory mechanisms is actually being used by the birds.

  15. Collective magnetic response of CeO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Coey, Michael; Ackland, Karl; Venkatesan, Munuswamy; Sen, Siddhartha

    2016-07-01

    The magnetism of nanoparticles and thin films of wide-bandgap oxides that include no magnetic cations is an unsolved puzzle. Progress has been hampered by both the irreproducibility of much of the experimental data, and the lack of any generally accepted theoretical explanation. The characteristic signature is a virtually anhysteretic, temperature-independent magnetization curve that saturates in an applied field that is several orders of magnitude greater than the magnetization. It would seem as if a tiny volume fraction, <~0.1%, of the samples is magnetic and that the energy scale is unusually high for spin magnetism. Here we investigate the effect of dispersing 4 nm CeO2 nanoparticles with powders of γAl2O3, sugar or latex microspheres. The saturation magnetization, Ms ≍ 60 A m-1 for compact samples, is maximized by 1 wt% lanthanum doping. Dispersing the CeO2 nanopowder reduces its magnetic moment by up to an order of magnitude, and there is a characteristic length scale of order 100 nm for the magnetism to appear in CeO2 nanoparticle clusters. The phenomenon is explained in terms of a giant orbital paramagnetism that appears in coherent mesoscopic domains due to resonant interaction with zero-point fluctuations of the vacuum electromagnetic field. The theory explains the observed temperature-independent magnetization curve and its doping and dispersion dependence, based on a length scale of 300 nm that corresponds to the wavelength of a maximum in the ultraviolet absorption spectrum of the magnetic CeO2 nanoparticles. The coherent domains occupy roughly 10% of the sample volume.

  16. Magnetic properties of ferritin and akaganeite nanoparticles in aqueous suspension

    NASA Astrophysics Data System (ADS)

    Koralewski, Marceli; Pochylski, Mikołaj; Gierszewski, Jacek

    2013-09-01

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

  17. Detection of molecules and cells using nuclear magnetic resonance with magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Rümenapp, Christine; Gleich, Bernhard; Mannherz, Hans Georg; Haase, Axel

    2015-04-01

    For the detection of small molecules, proteins or even cells in vitro, functionalised magnetic nanoparticles and nuclear magnetic resonance measurements can be applied. In this work, magnetic nanoparticles with the size of 5-7 nm were functionalised with antibodies to detect two model systems of different sizes, the protein avidin and Saccharomyces cerevisiae as the model organism. The synthesised magnetic nanoparticles showed a narrow size distribution, which was determined using transmission electron microscopy and dynamic light scattering. The magnetic nanoparticles were functionalised with the according antibodies via EDC/NHS chemistry. The binding of the antigen to magnetic nanoparticles was detected through the change in the NMR T2 relaxation time at 0.5 T (≈21.7 MHz). In case of a specific binding the particles cluster and the T2 relaxation time of the sample changes. The detection limit in buffer for FITC-avidin was determined to be 1.35 nM and 107 cells/ml for S. cerevisiae. For fluorescent microscopy the avidin molecules were labelled with FITC and for the detection of S. cerevisiae the magnetic nanoparticles were additionally functionalised with rhodamine. The binding of the particles to S. cerevisiae and the resulting clustering was also seen by transmission electron microscopy.

  18. The unusual magnetism of nanoparticle LaCoO3

    DOE PAGES

    Durand, A. M.; Belanger, D. P.; Hamil, T. J.; ...

    2015-04-15

    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≈85K 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,more » with the core region exhibiting the AFM crossover and with FM in the interface region near surfaces and impurity phases.« less

  19. Multiplex immunoassays of equine virus based on fluorescent encoded magnetic composite nanoparticles.

    PubMed

    Wang, Guannan; Gao, Yuan; Huang, Hui; Su, Xingguang

    2010-09-01

    A new detection format for multiplexed analysis based on fluorescent encoded magnetic composite nanoparticles is presented. Two kinds of virus were analyzed by this new method: equine influenza virus (EIV) and equine infectious anemia virus (EIAV). Firstly, EIV antigen and EIAV antigen were conjugated to two kinds of fluorescent encoded magnetic composite nanoparticles, while the green-emitting CdTe quantum dots (QDs) were attached to the antibody of EIV and EIAV. Then both green-emitting CdTe QD-labeled antibodies and antigens labeled with fluorescent encoded magnetic composite nanoparticles were used to form an immunoassay system for the detection of EIV and EIAV antigens. The method is time-saving and has higher sensitivity (1.3 ng mL(-1) for EIV antigens and 1.2 ng mL(-1) for EIAV antigens) than the conventional methods. A competitive immunoassay method based on this analysis system was used to detect EIV and EIAV antigens in spiked serum samples with satisfactory results.

  20. Manipulation and light-induced agglomeration of carbon nanotubes through optical trapping of attached silver nanoparticles.

    PubMed

    Shi, Chao; Zhang, Yi; Gu, Claire; Seballos, Leo; Zhang, Jin Z

    2008-05-28

    A simple experimental method has been demonstrated for manipulating multi-walled carbon nanotube (MWCNT) bundles through the optical trapping of attached silver nanoparticles (SNPs). In our experiments, without the SNPs, the MWCNTs cannot be trapped due to their irregular shapes and large aspect ratio. However, when mixed with SNPs, the MWCNTs can be successfully trapped along with the SNPs using a TEM(00) mode laser at 532 nm. This is attributed to the optical trapping of the SNPs and attractive interaction or binding between the SNPs and MWCNTs due to electrostatic and van der Waals forces. Therefore, optical manipulation of MWCNT bundles is achieved through the manipulation of the attached silver nanoparticles/aggregates. In addition, we have observed the phenomenon of light-induced further agglomeration of SNPs/MWCNTs which could potentially be exploited for fabricating patterned MWCNT films for future nanoscale devices and other applications.

  1. Vancomycin architecture dependence on the capture efficiency of antibody-modified microbeads by magnetic nanoparticles.

    PubMed

    Kell, Arnold J; Simard, Benoit

    2007-03-28

    We show that the ability to control the architecture/orientation of vancomycin on the surface of magnetic nanoparticles has a drastic effect on the ability of the nanoparticles to magnetically confine vancomycin-antibody modified polystyrene microbeads.

  2. 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

  3. Magnetic nanoparticles for enhancing the effectiveness of ultrasonic hyperthermia

    NASA Astrophysics Data System (ADS)

    Józefczak, A.; Kaczmarek, K.; Hornowski, T.; Kubovčíková, M.; Rozynek, Z.; Timko, M.; Skumiel, A.

    2016-06-01

    Ultrasonic hyperthermia is a method of cancer treatment in which tumors are exposed to an elevated cytotoxic temperature using ultrasound (US). In conventional ultrasonic hyperthermia, the ultrasound-induced heating in the tumor is achieved through the absorption of wave energy. However, to obtain appropriate temperature in reasonable time, high US intensities, which can have a negative impact on healthy tissues, are required. The effectiveness of US for medical purposes can be significantly improved by using the so-called sonosensitizers, which can enhance the thermal effect of US on the tissue by increasing US absorption. One possible candidate for such sonosensitizers is magnetic nanoparticles with mean sizes of 10-300 nm, which can be efficiently heated because of additional attenuation and scattering of US. Additionally, magnetic nanoparticles are able to produce heat in the alternating magnetic field (magnetic hyperthermia). The synergetic application of ultrasonic and magnetic hyperthermia can lead to a promising treatment modality.

  4. Physical justification for negative remanent magnetization in homogeneous nanoparticles.

    PubMed

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

    2014-09-03

    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.

  5. Influence of surface heterogeneities on reversibility of fullerene (nC60) nanoparticle attachment in saturated porous media.

    PubMed

    Shen, Chongyang; Zhang, Mengjia; Zhang, Shuzhen; Wang, Zhan; Zhang, Hongyan; Li, Baoguo; Huang, Yuanfang

    2015-06-15

    This study systematically investigated influence of surface roughness and surface chemical heterogeneity on attachment and detachment of nC60 nanoparticles in saturated porous media by conducting laboratory column experiments. Sand and glass beads were employed as a model collectors to represent a different surface roughness. The two collectors were treated by washing with only deionized water or by using acids to extensively remove chemical heterogeneities. Results show that both attachment and detachment were more in the acid-treated sand than those in the acid-treated glass beads. The greater attachment and detachment were attributed to the reason that sand surfaces have much more nanoscale asperities, which facilitates particle attachment atop of them at primary minima and subsequent detachment upon reduction of ionic strength. No detachment was observed if the water-washed collectors were employed, demonstrating that the couple of chemical heterogeneity with nanoscale roughness causes irreversible attachment in primary minima. Whereas existing studies frequently represented surface rough asperities as regular geometries (e.g., hemisphere, cone, pillar) for estimating influence of surface roughness on Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energies, our theoretical calculations indicate that the assumptions could underestimate both attachment and detachment because these geometries cannot account for surface curvature effects.

  6. Single-nanoparticle-terminated tips for scanning probe microscopy.

    PubMed

    Vakarelski, Ivan U; Higashitani, Ko

    2006-03-28

    We have developed a wet-chemistry procedure to attach a 10-40 nm colloidal gold nanoparticle to the top of a scanning probe microscopy (SPM) probe tip, making experiments of single nanoparticle interaction possible. This procedure of particle attachment is flexible and can be modified to attach nanoparticles of different kinds and sizes. The single-nanoparticle-terminated tips also have potential in various other applications, such as probes of enhanced sensitivity for optical and magnetic modes SPM.

  7. Fiber magnetic-field sensor based on nanoparticle magnetic fluid and Fresnel reflection.

    PubMed

    Chen, Luan Xiong; Huang, Xu Guang; Zhu, Jia Hu; Li, Guang Can; Lan, Sheng

    2011-08-01

    A simple fiber sensor for magnetic field measurement based on nanoparticle Fe(3)O(4) magnetic fluid and relative Fresnel reflection is presented. The sensor includes only a light source, three couplers, two photodetectors, and two fiber sensing ends. Magnetic fields at different concentrations of magnetic fluid are measured. Magnetic fluid with high concentration can be used for the measurement of weak magnetic fields, while low concentration fluid is used for the measurement of strong magnetic fields. The temperature dependence of the sensor is also addressed.

  8. Switching of magnetization by nonlinear resonance studied in single nanoparticles

    NASA Astrophysics Data System (ADS)

    Thirion, Christophe; Wernsdorfer, Wolfgang; Mailly, Dominique

    2003-08-01

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

  9. Magnetic nanoparticles supported ionic liquids improve firefly luciferase properties.

    PubMed

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

    2014-03-01

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

  10. Magnetic conjugated polymer nanoparticles as bimodal imaging agents.

    PubMed

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

    2010-07-21

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

  11. A novel strategy for functionalizable photoluminescent magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  12. Unconventional Magnetism in Low Carrier Density Systems and Nanoparticle Composites

    SciTech Connect

    Meigan C Aronson

    2008-06-14

    Under the auspices of this funding, we have developed a program to synthesize and characterize highly monodispersed magnetic nanoparticles. We have been particularly interested in the origin of the exchange bias effect, which occurs in compound nanoparticles with a ferromagnetic core and an antiferromagnetic shell, and have mostly focused on Co/CoO core-shell nanoparticles. The exchange bias effect involves exchange coupling between the core moment and the antiferromagnetic shell which stabilizes the core moment, which would otherwise be quickly reorienting in ferromagnetic particles of this size.

  13. Copper nanoparticles functionalized PE: Preparation, characterization and magnetic properties

    NASA Astrophysics Data System (ADS)

    Reznickova, A.; Orendac, M.; Kolska, Z.; Cizmar, E.; Dendisova, M.; Svorcik, V.

    2016-12-01

    We report grafting of copper nanoparticles (CuNP) on plasma activated high density polyethylene (HDPE) via dithiol interlayer pointing out to the structural and magnetic properties of those composites. The as-synthesized Cu nanoparticles have been characterized by high-resolution transmission electron microscopy (HRTEM/TEM) and UV-vis spectroscopy. Properties of pristine PE and their plasma treated counterparts were studied by different experimental techniques: X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy, energy dispersive X-ray spectroscopy (EDS), zeta potential, electron spin resonance (ESR) and SQUID magnetometry. From TEM and HRTEM analyses, it is found that the size of high purity Cu nanoparticles is (12.2 ± 5.2) nm. It was determined that in the CuNPs, the copper atoms are arranged mostly in the (111) and (200) planes. Absorption in UV-vis region by these nanoparticles is ranging from 570 to 670 nm. EDS revealed that after 1 h of grafting are Cu nanoparticles homogeneously distributed over the whole surface and after 24 h of grafting Cu nanoparticles tend to aggregate slightly. The combined investigation of magnetic properties using ESR spectrometry and SQUID magnetometry confirmed the presence of copper nanoparticles anchored on PE substrate and indicated ferromagnetic interactions.

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

    PubMed Central

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

    2013-01-01

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

  15. Ferrohydrodynamic modeling of magnetic nanoparticle harmonic spectra for magnetic particle imaging

    PubMed Central

    Dhavalikar, Rohan; Maldonado-Camargo, Lorena; Garraud, Nicolas; Rinaldi, Carlos

    2015-01-01

    Magnetic Particle Imaging (MPI) is an emerging imaging technique that uses magnetic nanoparticles as tracers. In order to analyze the quality of nanoparticles developed for MPI, a Magnetic Particle Spectrometer (MPS) is often employed. In this paper, we describe results for predictions of the nanoparticle harmonic spectra obtained in a MPS using three models: the first uses the Langevin function, which does not take into account finite magnetic relaxation; the second model uses the magnetization equation by Shliomis (Sh), which takes into account finite magnetic relaxation using a constant characteristic time scale; and the third model uses the magnetization equation derived by Martsenyuk, Raikher, and Shliomis (MRSh), which takes into account the effect of magnetic field magnitude on the magnetic relaxation time. We make comparisons between these models and with experiments in order to illustrate the effects of field-dependent relaxation in the MPS. The models results suggest that finite relaxation results in a significant drop in signal intensity (magnitude of individual harmonics) and in faster spectral decay. Interestingly, when field dependence of the magnetic relaxation time was taken into account, through the MRSh model, the simulations predict a significant improvement in the performance of the nanoparticles, as compared to the performance predicted by the Sh equation. The comparison between the predictions from models and experimental measurements showed excellent qualitative as well as quantitative agreement up to the 19th harmonic using the Sh and MRSh equations, highlighting the potential of ferrohydrodynamic modeling in MPI. PMID:26576063

  16. Multifunctional magnetic nanoparticles modified with polyethylenimine and folic acid for biomedical theranostics.

    PubMed

    Yoo, Hyunhee; Moon, Seung-Kwan; Hwang, Taewon; Kim, Yong Seok; Kim, Joo-Hwan; Choi, Sung-Wook; Kim, Jung Hyun

    2013-05-21

    This paper describes the preparation of magnetic nanoparticles modified with polyethylenimine (PEI)-folic acid (PF) conjugate and their potential biomedical applications. Magnetic nanoparticles modified with (3-(2-aminoethylamino)propyltrimethoxysilane) (AEAPS) were first prepared using a ligand exchange method to provide biocompatibility and hydrophilicity, and further conjugated with PF to carry gene and enhance specific uptake into cancer cells. We demonstrated the feasibility of the multifunctional magnetic nanoparticles as contrast agents in magnetic resonance imaging (MRI) and as gene carriers for gene delivery. In vitro results revealed that the cytotoxicity of the multifunctional magnetic nanoparticles was lower compared to that of pristine magnetic nanoparticles. Furthermore, we demonstrated the specific uptake of the magnetic nanoparticles modified with PF to KB cells using WI-38 cells as comparison by confocal microscopy. The PF-modified magnetic nanoparticles can potentially be employed as theranostic nanoplatforms for targeted gene delivery to cancer cells and simultaneous magnetic resonance imaging.

  17. Harmonics based detection of magnetic nanoparticle dynamics for multiparameter biosensing

    NASA Astrophysics Data System (ADS)

    Rauwerdink, Adam M.

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

  18. T1-T2 Dual-modal MRI contrast agents based on superparamagnetic iron oxide nanoparticles with surface attached gadolinium complexes

    NASA Astrophysics Data System (ADS)

    Szpak, Agnieszka; Fiejdasz, Sylwia; Prendota, Witold; Strączek, Tomasz; Kapusta, Czesław; Szmyd, Janusz; Nowakowska, Maria; Zapotoczny, Szczepan

    2014-11-01

    Dual-mode MRI contrast agents consisting of superparamagnetic iron oxide nanoparticle (SPION) cores and gadolinium ions associated with the ionic chitosan protecting layer were synthesized and studied. Gadolinium ions were introduced into the coating layer via direct complex formation on the nanoparticles surface, covalent attachment or electrostatically driven deposition of the preformed Gd complex. The modified SPIONs having hydrodynamic diameters ca. 100 nm form stable, well-defined dispersions in water and have excellent magnetic properties. Physiochemical properties of those new materials were characterized using e.g., FTIR spectroscopy, dynamic light scattering, X-ray fluorescence, TEM, and vibrating sample magnetometry. They behave as superparamagnetics and shorten both T1 and T2 proton relaxation times, thus influencing both r1 and r2 relaxivity values that reach 53.7 and 375.5 mM-1 s-1, respectively, at 15 MHz. The obtained materials can be considered as highly effective contrast agents for low-field MRI, particularly useful at permanent magnet-based scanners.

  19. Magnetic nanoparticle and magnetic field assisted siRNA delivery in vitro.

    PubMed

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

    2015-01-01

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

  20. Cubic versus spherical magnetic nanoparticles: the role of surface anisotropy.

    PubMed

    Salazar-Alvarez, G; Qin, J; Sepelák, V; Bergmann, I; Vasilakaki, M; Trohidou, K N; Ardisson, J D; Macedo, W A A; Mikhaylova, M; Muhammed, M; Baró, M D; Nogués, J

    2008-10-08

    The magnetic properties of maghemite (gamma-Fe2O3) cubic and spherical nanoparticles of similar sizes have been experimentally and theoretically studied. The blocking temperature, T(B), of the nanoparticles depends on their shape, with the spherical ones exhibiting larger T(B). Other low temperature properties such as saturation magnetization, coercivity, loop shift or spin canting are rather similar. The experimental effective anisotropy and the Monte Carlo simulations indicate that the different random surface anisotropy of the two morphologies combined with the low magnetocrystalline anisotropy of gamma-Fe2O3 is the origin of these effects.

  1. Magnetic fluid hyperthermia: focus on superparamagnetic iron oxide nanoparticles.

    PubMed

    Laurent, Sophie; Dutz, Silvio; Häfeli, Urs O; Mahmoudi, Morteza

    2011-08-10

    Due to their unique magnetic properties, excellent biocompatibility as well as multi-purpose biomedical potential (e.g., applications in cancer therapy and general drug delivery), superparamagnetic iron oxide nanoparticles (SPIONs) are attracting increasing attention in both pharmaceutical and industrial communities. The precise control of the physiochemical properties of these magnetic systems is crucial for hyperthermia applications, as the induced heat is highly dependent on these properties. In this review, the limitations and recent advances in the development of superparamagnetic iron oxide nanoparticles for hyperthermia are presented.

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

    PubMed

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

    2013-12-15

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

  3. A novel electrode surface fabricated by directly attaching gold nanoparticles onto NH2+ ions implanted-indium tin oxide substrate

    NASA Astrophysics Data System (ADS)

    Liu, Chenyao; Jiao, Jiao; Chen, Qunxia; Xia, Ji; Li, Shuoqi; Hu, Jingbo; Li, Qilong

    2010-12-01

    A new type of gold nanoparticle attached to a NH2+ ion implanted-indium tin oxide surface was fabricated without using peculiar binder molecules, such as 3-(aminopropyl)-trimethoxysilane. A NH 2/indium tin oxide film was obtained by implantation at an energy of 80 keV with a fluence of 5 × 10 15 ions/cm 2. The gold nanoparticle-modified film was characterized by X-ray photoelectron spectroscopy, scanning electron microscopy and electrochemical techniques and compared with a modified bare indium tin oxide surface and 3-(aminopropyl)-trimethoxysilane linked surface, which exhibited a relatively low electron transfer resistance and high electrocatalytic activity. The results demonstrate that NH2+ ion implanted-indium tin oxide films can provide an important route to immobilize nanoparticles, which is attractive in developing new biomaterials.

  4. Thermal activation in statistical clusters of magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Hovorka, O.

    2017-02-01

    This article presents a kinetic Monte-Carlo study of thermally activated magnetisation dynamics in clusters of statistically distributed magnetic nanoparticles. The structure of clusters is assumed to be of fractal nature, consistently with recent observations of magnetic particle aggregation in cellular environments. The computed magnetisation relaxation decay and frequency-dependent hysteresis loops are seen to significantly depend on the fractal dimension of aggregates, leading to accelerated magnetisation relaxation and reduction in the size of hysteresis loops as the fractal dimension increases from one-dimensional-like to three-dimensional-like clusters. Discussed are implications for applications in nanomedicine, such as magnetic hyperthermia or magnetic particle imaging.

  5. Effects of nanoparticle coatings on the activity of oncolytic adenovirus-magnetic nanoparticle complexes.

    PubMed

    Tresilwised, Nittaya; Pithayanukul, Pimolpan; Holm, Per Sonne; Schillinger, Ulrike; Plank, Christian; Mykhaylyk, Olga

    2012-01-01

    Limitations to adenovirus infectivity can be overcome by association with magnetic nanoparticles and enforced infection by magnetic field influence. Here we examined three core-shell-type iron oxide magnetic nanoparticles differing in their surface coatings, particle sizes and magnetic properties for their ability to enhance the oncolytic potency of adenovirus Ad520 and to stabilize it against the inhibitory effects of serum or a neutralizing antibody. It was found that the physicochemical properties of magnetic nanoparticles are critical determinants of the properties which govern the oncolytic productivities of their complexes with Ad520. Although high serum concentration during infection or a neutralizing antibody had strong inhibitory influence on the uptake or oncolytic productivity of the naked virus, one particle type was identified which conferred high protection against both inhibitory factors while enhancing the oncolytic productivity of the internalized virus. This particle type equipped with a silica coating and adsorbed polyethylenimine, displaying a high magnetic moment and high saturation magnetization, mediated a 50% reduction of tumor growth rate versus control upon intratumoral injection of its complex with Ad520 and magnetic field influence, whereas Ad520 alone was inefficient. The correlations between physical properties of the magnetic particles or virus complexes and oncolytic potency are described herein.

  6. 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.

  7. Nuclear-Targeted Multifunctional Magnetic Nanoparticles for Photothermal Therapy.

    PubMed

    Peng, Haibao; Tang, Jing; Zheng, Rui; Guo, Guannan; Dong, Angang; Wang, Yajun; Yang, Wuli

    2017-01-27

    The pursuit of multifunctional, innovative, more efficient, and safer cancer treatment has gained increasing interest in the research of preclinical nanoparticle-mediated photothermal therapy (PTT). Cell nucleus is recognized as the ideal target for cancer treatment because it plays a central role in genetic information and the transcription machinery reside. In this work, an efficient nuclear-targeted PTT strategy is proposed using transferrin and TAT peptide (TAT: YGRKKRRQRRR) conjugated monodisperse magnetic nanoparticles, which can be readily functionalized and stabilized for potential diagnostic and therapeutic applications. The monodisperse magnetic nanoparticles exhibit high photothermal conversion efficiency (≈37%) and considerable photothermal stability. They also show a high magnetization value and transverse relaxivity (207.1 mm(-1) s(-1) ), which could be applied for magnetic resonance imaging. The monodisperse magnetic nanoparticles conjugated with TAT peptides can efficiently target the nucleus and achieve the imaging-guided function, efficient cancer cells killing ability. Therefore, this work may present a practicable strategy to develop subcellular organelle targeted PTT agents for simultaneous cancer targeting, imaging, and therapy.

  8. Structure and magnetism in Cr-embedded Co nanoparticles.

    PubMed

    Baker, S H; Kurt, M S; Roy, M; Lees, M R; Binns, C

    2016-02-03

    We present the results of an investigation into the atomic structure and magnetism of 2 nm diameter Co nanoparticles embedded in an antiferromagnetic Cr matrix. The nanocomposite films used in this study were prepared by co-deposition directly from the gas phase, using a gas aggregation source for the Co nanoparticles and a molecular beam epitaxy (MBE) source for the Cr matrix material. Co K and Cr K edge extended x-ray absorption fine structure (EXAFS) experiments were performed in order to investigate atomic structure in the embedded nanoparticles and matrix respectively, while magnetism was investigated by means of a vibrating sample magnetometer. The atomic structure type of the Co nanoparticles is the same as that of the Cr matrix (bcc) although with a degree of disorder. The net Co moment per atom in the Co/Cr nanocomposite films is significantly reduced from the value for bulk Co, and decreases as the proportion of Co nanoparticles in the film is decreased; for the sample with the most dilute concentration of Co nanoparticles (4.9% by volume), the net Co moment was 0.25 μ B/atom. After field cooling to below 30 K all samples showed an exchange bias, which was largest for the most dilute sample. Both the structural and magnetic results point towards a degree of alloying at the nanoparticle/matrix interface, leading to a core/shell structure in the embedded nanoparticles consisting of an antiferromagnetic CoCr alloy shell surrounding a reduced ferromagnetic Co core.

  9. An update on clinical applications of magnetic nanoparticles for increasing the resolution of magnetic resonance imaging.

    PubMed

    Zeinali Sehrig, Fatemeh; Majidi, Sima; Asvadi, Sahar; Hsanzadeh, Arash; Rasta, Seyed Hossein; Emamverdy, Masumeh; Akbarzadeh, Jamshid; Jahangiri, Sahar; Farahkhiz, Shahrzad; Akbarzadeh, Abolfazl

    2016-11-01

    Today, technologies based on magnetic nanoparticles (MNPs) are regularly applied to biological systems with diagnostic or therapeutic aims. Nanoparticles made of the elements iron (Fe), gadolinium (Gd) or manganese (Mn) are generally used in many diagnostic applications performed under magnetic resonance imaging (MRI). Similar to molecular-based contrast agents, nanoparticles can be used to increase the resolution of imaging while offering well biocompatibility, poisonousness and biodistribution. Application of MNPs enhanced MRI sensitivity due to the accumulation of iron in the liver caused by discriminating action of the hepatobiliary system. The aim of this study is about the use, properties and advantages of MNPs in MRI.

  10. Taking a hard line with biotemplating: cobalt-doped magnetite magnetic nanoparticle arrays.

    PubMed

    Bird, Scott M; Galloway, Johanna M; Rawlings, Andrea E; Bramble, Jonathan P; Staniland, Sarah S

    2015-04-28

    Rapid advancements made in technology, and the drive towards miniaturisation, means that we require reliable, sustainable and cost effective methods of manufacturing a wide range of nanomaterials. In this bioinspired study, we take advantage of millions of years of evolution, and adapt a biomineralisation protein for surface patterning of biotemplated magnetic nanoparticles (MNPs). We employ soft-lithographic micro-contact printing to pattern a recombinant version of the biomineralisation protein Mms6 (derived from the magnetotactic bacterium Magnetospirillum magneticum AMB-1). The Mms6 attaches to gold surfaces via a cysteine residue introduced into the N-terminal region. The surface bound protein biotemplates highly uniform MNPs of magnetite onto patterned surfaces during an aqueous mineralisation reaction (with a mean diameter of 90 ± 15 nm). The simple addition of 6% cobalt to the mineralisation reaction maintains the uniformity in grain size (with a mean diameter of 84 ± 14 nm), and results in the production of MNPs with a much higher coercivity (increased from ≈ 156 Oe to ≈ 377 Oe). Biotemplating magnetic nanoparticles on patterned surfaces could form a novel, environmentally friendly route for the production of bit-patterned media, potentially the next generation of ultra-high density magnetic data storage devices. This is a simple method to fine-tune the magnetic hardness of the surface biotemplated MNPs, and could easily be adapted to biotemplate a wide range of different nanomaterials on surfaces to create a range of biologically templated devices.

  11. β-Lactoglobulin (BLG) binding to highly charged cationic polymer-grafted magnetic nanoparticles: effect of ionic strength.

    PubMed

    Qin, Li; Xu, Yisheng; Han, Haoya; Liu, Miaomiao; Chen, Kaimin; Wang, Siyi; Wang, Jie; Xu, Jun; Li, Li; Guo, Xuhong

    2015-12-15

    Poly(2-(methacryloyloxy)ethyltrimethyl ammonium chloride) (PMATAC) modified magnetic nanoparticles (NPs) with a high zeta potential of ca. 50mV were synthesized by atom transfer radical polymerization (ATRP). The prepared NPs consist of a magnetic core around 13nm and a PMATAC shell around 20nm attached on the surface of magnetic nanoparticles. Thermodynamic binding parameters between β-lactoglobulin and these polycationic NPs were investigated at different ionic strengths by high-resolution turbidimetry, dynamic light scattering (DLS), and isothermal titration calorimetry (ITC). Both turbidity and ITC show that binding affinities for BLG display a non-monotonic ionic strength dependence trend and a maximum appears at ionic strength of 50mM. Such observation should arise from the coeffects of protein charge anisotropy visualized by DelPhi electrostatic modeling and the strong electrostatic repulsion among highly charged NPs at a variety of ionic strengths.

  12. Versatile magnetometer assembly for characterizing magnetic properties of nanoparticles

    NASA Astrophysics Data System (ADS)

    Araujo, J. F. D. F.; Bruno, A. C.; Louro, S. R. W.

    2015-10-01

    We constructed a versatile magnetometer assembly for characterizing iron oxide nanoparticles. The magnetometer can be operated at room temperature or inside a cryocooler at temperatures as low as 6 K. The magnetometer's sensor can be easily exchanged and different detection electronics can be used. We tested the assembly with a non-cryogenic commercial Hall sensor and a benchtop multimeter in a four-wire resistance measurement scheme. A magnetic moment sensitivity of 8.5 × 10-8 Am2 was obtained with this configuration. To illustrate the capability of the assembly, we synthesized iron oxide nanoparticles coated with different amounts of a triblock copolymer, Pluronic F-127, and characterized their magnetic properties. We determined that the polymer coating does not affect the magnetization of the particles at room temperature and demonstrates that it is possible to estimate the average size of coating layers from measurements of the magnetic field of the sample.

  13. Versatile magnetometer assembly for characterizing magnetic properties of nanoparticles.

    PubMed

    Araujo, J F D F; Bruno, A C; Louro, S R W

    2015-10-01

    We constructed a versatile magnetometer assembly for characterizing iron oxide nanoparticles. The magnetometer can be operated at room temperature or inside a cryocooler at temperatures as low as 6 K. The magnetometer's sensor can be easily exchanged and different detection electronics can be used. We tested the assembly with a non-cryogenic commercial Hall sensor and a benchtop multimeter in a four-wire resistance measurement scheme. A magnetic moment sensitivity of 8.5 × 10(-8) Am(2) was obtained with this configuration. To illustrate the capability of the assembly, we synthesized iron oxide nanoparticles coated with different amounts of a triblock copolymer, Pluronic F-127, and characterized their magnetic properties. We determined that the polymer coating does not affect the magnetization of the particles at room temperature and demonstrates that it is possible to estimate the average size of coating layers from measurements of the magnetic field of the sample.

  14. Versatile magnetometer assembly for characterizing magnetic properties of nanoparticles

    SciTech Connect

    Araujo, J. F. D. F.; Bruno, A. C.; Louro, S. R. W.

    2015-10-15

    We constructed a versatile magnetometer assembly for characterizing iron oxide nanoparticles. The magnetometer can be operated at room temperature or inside a cryocooler at temperatures as low as 6 K. The magnetometer’s sensor can be easily exchanged and different detection electronics can be used. We tested the assembly with a non-cryogenic commercial Hall sensor and a benchtop multimeter in a four-wire resistance measurement scheme. A magnetic moment sensitivity of 8.5 × 10{sup −8} Am{sup 2} was obtained with this configuration. To illustrate the capability of the assembly, we synthesized iron oxide nanoparticles coated with different amounts of a triblock copolymer, Pluronic F-127, and characterized their magnetic properties. We determined that the polymer coating does not affect the magnetization of the particles at room temperature and demonstrates that it is possible to estimate the average size of coating layers from measurements of the magnetic field of the sample.

  15. Cell labeling with magnetic nanoparticles: opportunity for magnetic cell imaging and cell manipulation.

    PubMed

    Kolosnjaj-Tabi, Jelena; Wilhelm, Claire; Clément, Olivier; Gazeau, Florence

    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.

  16. Structural and magnetic properties of L10 -FePt nanoparticles aligned by external magnetic field

    NASA Astrophysics Data System (ADS)

    Tamada, Yoshinori; Yamamoto, Shinpei; Nasu, Saburo; Ono, Teruo

    2008-12-01

    We investigated structural and magnetic properties of the easy-axis aligned L10 -FePt nanoparticles by the combined use of x-ray diffraction (XRD), magnetization, and F57e Mössbauer measurements. The L10 -FePt nanoparticles were fixed in a polystyrene matrix by performing free radical polymerization of styrene under an aligning external magnetic field. Mössbauer spectrum of the L10 -FePt nanoparticles/polystyrene composite showed tremendous decrease in the second and fifth absorption lines under the condition that the incident γ ray was parallel to the aligning field. This result indicates that the easy axes of the L10 -FePt nanoparticles in the composite have a strong preferred orientation with a finite distribution. We estimated the distribution of easy-axis orientation by using the Mössbauer hyperfine parameters, which is in good agreement with that determined by the XRD rocking curve.

  17. The Colloidal Stability of Magnetic Nanoparticles in Ionic Liquids

    DTIC Science & Technology

    2014-09-01

    SEP 2014 2. REPORT TYPE Final 3. DATES COVERED 06-03-2013 to 05-06-2014 4. TITLE AND SUBTITLE The Colloidal Stability of Magnetic...DATES COVERED (From - To) 6 Mar 2013 – 5 June 2014 4. TITLE AND SUBTITLE The Colloidal Stability of Magnetic Nanoparticles in Ionic Liquids...Polymers and Colloids , Chemistry F11, The University of Sydney, NSW 2006, Australia. - Phone : +61 2 9351 6973 - Fax : +61 2 9351 851 Period of

  18. Synthesis and characterizations of novel magnetic and plasmonic nanoparticles

    NASA Astrophysics Data System (ADS)

    Dahal, Naween

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

  19. Magnetic nanoparticles for thermal lysis and application in cancer treatment

    NASA Astrophysics Data System (ADS)

    Das, Sumana; Javvaji, Brahmanandam; Veerla, Sarath Chandra; Roy Mahapatra, D.

    2016-03-01

    Chemotherapy and radiation-therapy are conventional treatment procedure of cancer. Though radiation therapy is very common practice for cancer treatment, it has limitations including incomplete and non specific destruction. Heating characteristics of magnetic nanoparticle (MNP) is modelled using molecular dynamics simulation setup. This model would give an understanding for the treatment of cancer cell through MNP associated radiation-therapy. In this paper, alternating magnetic field driven heat generation of MNP is studied using classical molecular dynamics. Temperature is measured as an ensemble average of velocity of the atoms. Temperature stabilization is achieved. Under this simulation setting with certain parameters, 45°C temperature was obtained in our simulations. Simulation data would be helpful for experimental analysis to treat cancerous cell in presence of MNP under exposure to radiofrequency. The in vitro thermal characteristics of magnetite nanoparticles using magnetic coil of various frequencies (5, 7.5, 10 and 15 kHz), the saturation temperature was found at 0.5 mg/mL concentration. At frequency 50 kHz the live/dead and MTT assay was performed on magnetite nanoparticles using MC3T3 cells for 10 min duration. Low radio frequency (RF) radiation induced localized heat into the metallic nanoparticles which is clearly understood using the molecular dynamics simulation setup. Heating of nanoparticle trigger the killing of the tumor cells, acts as a local therapy, as it generates less side effects in comparison to other treatments like chemotherapy and radiation therapy.

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

    PubMed

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

    2012-07-24

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

  1. Engineering spatial gradients of signaling proteins using magnetic nanoparticles.

    PubMed

    Bonnemay, L; Hostachy, S; Hoffmann, C; Gautier, J; Gueroui, Z

    2013-11-13

    Intracellular biochemical reactions are often localized in space and time, inducing gradients of enzymatic activity that may play decisive roles in determining cell's fate and functions. However, the techniques available to examine such enzymatic gradients of activity remain limited. Here, we propose a new method to engineer a spatial gradient of signaling protein concentration within Xenopus egg extracts using superparamagnetic nanoparticles. We show that, upon the application of a magnetic field, a concentration gradient of nanoparticles with a tunable length extension is established within confined egg extracts. We then conjugate the nanoparticles to RanGTP, a small G-protein controlling microtubule assembly. We found that the generation of an artificial gradient of Ran-nanoparticles modifies the spatial positioning of microtubule assemblies. Furthermore, the spatial control of the level of Ran concentration allows us to correlate the local fold increase in Ran-nanoparticle concentration with the spatial positioning of the microtubule-asters. Our assay provides a bottom-up approach to examine the minimum ingredients generating polarization and symmetry breaking within cells. More generally, these results show how magnetic nanoparticles and magnetogenetic tools can be used to control the spatiotemporal dynamics of signaling pathways.

  2. Magnetic nanoparticles: A multifunctional vehicle for modern theranostics.

    PubMed

    Angelakeris, M

    2017-02-20

    Magnetic nanoparticles provide a unique multifunctional vehicle for modern theranostics since they can be remotely and non-invasively employed as imaging probes, carrier vectors and smart actuators. Additionally, special delivery schemes beyond the typical drug delivery such as heat or mechanical stress may be magnetically triggered to promote certain cellular pathways. To start with, we need magnetic nanoparticles with several well-defined and reproducible structural, physical, and chemical features, while bio-magnetic nanoparticle design imposes several additional constraints. Except for the intrinsic requirement for high quality of magnetic properties in order to obtain the maximum efficiency with the minimum dose, the surface manipulation of the nanoparticles is a key aspect not only for transferring them from the growth medium to the biological environment but also to bind functional molecules that will undertake specific targeting, drug delivery, cell-specific monitoring and designated treatment without sparing biocompatibility and sustainability in-vivo. The ability of magnetic nanoparticles to interact with matter at the nanoscale not only provides the possibility to ascertain the molecular constituents of a disease, but also the way in which the totality of a biological function may be affected as well. The capacity to incorporate an array of structural and chemical functionalities onto the same nanoscale architecture also enables more accurate, sensitive and precise screening together with cure of diseases with significant pathological heterogeneity such as cancer. This article is part of a Special Issue entitled "Recent Advances in Bionanomaterials" Guest Editor: Dr. Marie-Louise Saboungi and Dr. Samuel D. Bader.

  3. Theoretical studies to elucidate the influence of magnetic dipolar interactions occurring in the magnetic nanoparticle systems, for biomedical applications

    NASA Astrophysics Data System (ADS)

    Osaci, M.; Cacciola, M.

    2016-02-01

    In recent years, the study of magnetic nanoparticles has been intensively developed not only for their fundamental theoretical interest, but also for their many technological applications, especially biomedical applications, ranging from contrast agents for magnetic resonance imaging to the deterioration of cancer cells via hyperthermia treatment. The theoretical and experimental research has shown until now that the magnetic dipolar interactions between nanoparticles can have a significant influence on the magnetic behaviour of the system. But, this influence is not well understood. It is clear that the magnetic dipolar interaction intensity is correlated with the nanoparticle concentration, volume fraction and magnetic moment orientations. In this paper, we try to understand the influence of magnetic dipolar interactions on the behaviour of magnetic nanoparticle systems, for biomedical applications. For the model, we considered spherical nanoparticles with uniaxial anisotropy and lognormal distribution of the sizes. The model involves a simulation stage of the spatial distribution and orientation of the nanoparticles and their easy axes of magnetic anisotropy, and an evaluation stage of the Néel relaxation time. To assess the Néel relaxation time, we are going to discretise and adapt, to the local magnetic field, the Coffey analytical solution for the equation Fokker-Planck describing the dynamics of magnetic moments of nanoparticles in oblique external magnetic field. There are three fundamental aspects of interest in our studies on the magnetic nanoparticles: their spatial & orientational distributions, concentrations and sizes.

  4. Enzymatic conversion of magnetic nanoparticles to a non-magnetic precipitate: a new approach to magnetic sensing.

    PubMed

    Kolhatkar, Arati G; Jamison, Andrew C; Nekrashevich, Ivan; Kourentzi, Katerina; Litvinov, Dmitri; Brazdeikis, Audrius; Willson, Richard C; Randall Lee, T

    2016-09-21

    Magnetic sensing utilizes the detection of biomolecule-conjugated magnetic nanoparticles (MNPs). Our new strategy offers a novel approach to magnetic sensing where in situ conversion produces a "loss of signal" in the sensing device. This report demonstrates the enzymatic conversion of Fe3O4 MNPs to a non-magnetic precipitate via reduction by l-ascorbic acid generated by the action of alkaline phosphatase.

  5. Corrosion characteristics of ferric and austenitic stainless steels for dental magnetic attachment.

    PubMed

    Endo, K; Suzuki, M; Ohno, H

    2000-03-01

    The corrosion behaviors of four ferric stainless steels and two austenitic stainless steels were examined in a simulated physiological environment (0.9% NaCl solution) to obtain basic data for evaluating the appropriate composition of stainless steels for dental magnetic attachments. The corrosion resistance was evaluated by electrochemical techniques and the analysis of released metal ions by atomic absorption spectrophotometry. The surface of the stainless steels was analyzed by X-ray photoelectron spectroscopy (XPS). The breakdown potential of ferric stainless steels increased and the total amount of released metal ions decreased linearly with increases in the sum of the Cr and Mo contents. The corrosion rate of the ferric stainless steels increased 2 to 6 times when they were galvanically coupled with noble metal alloys but decreased when coupled with commercially pure Ti. For austenitic stainless steels, the breakdown potential of high N-bearing stainless steel was approximately 500 mV higher than that of SUS316L, which is currently used as a component in dental magnetic attachments. The enriched nitrogen at the alloy/passive film interface may be effective in improving the localized corrosion resistance.

  6. Electro-magnetic Templates with Magnetic Nanoparticles for Cell-based Assays

    NASA Astrophysics Data System (ADS)

    Gertz, Frederick; Khitun, Alexander

    We discuss the possibility of a specially designed electro-magnetic template with magnetic nanoparticles for cell-based-assays. There is an urgent need for a special type of hardware allowing for biological cell manipulation. We have developed an original technique of using electro-magnetic templates with magnetic nanoparticles for biological cell manipulation. The essence of this approach is to generate a non-uniform magnetic field profile using a system of electric current carrying wires. The gradient of the magnetic field results in the movement of the nanoparticles towards the magnetic energy minima. In turn, the flow of magnetic nanoparticles drags biological cells in the same direction. We present experimental data on biological cells (erythrocytes) manipulations by magnetite (Fe3O4) on specially designed templates The results show controlled biological cell motion and destruction via haemolysis. This technique allows us to capture and to move cells located in the vicinity (10-20 microns) of the current-carrying wires. One of the most interesting results shows a periodic motion of erythrocytes between the two conducting contours, which frequency is controlled by the electric circuit. The obtained results demonstrate the feasibility of cell manipulation which can be utilized in cell-based assays.

  7. 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.

  8. Particle size- and concentration-dependent separation of magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Witte, Kerstin; Müller, Knut; Grüttner, Cordula; Westphal, Fritz; Johansson, Christer

    2017-04-01

    Small magnetic nanoparticles with a narrow size distribution are of great interest for several biomedical applications. When the size of the particles decreases, the magnetic moment of the particles decreases. This leads to a significant increase in the separation time by several orders of magnitude. Therefore, in the present study the separation processes of bionized nanoferrites (BNF) with different sizes and concentrations were investigated with the commercial Sepmag Q system. It was found that an increasing initial particle concentration leads to a reduction of the separation time for large nanoparticles due to the higher probability of building chains. Small nanoparticles showed exactly the opposite behavior with rising particle concentration up to 0.1 mg(Fe)/ml. For higher iron concentrations the separation time remains constant and the measured Z-average decreases in the supernatant at same time intervals. At half separation time a high yield with decreasing hydrodynamic diameter of particles can be obtained using higher initial particle concentrations.

  9. Tailoring magnetic properties of core/shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Zeng, Hao; Sun, Shouheng; Li, J.; Wang, Z. L.; Liu, J. P.

    2004-08-01

    Bimagnetic FePt /MFe2O4(M =Fe,Co) core/shell nanoparticles are synthesized via high-temperature solution phase coating of 3.5nm FePt core with MFe2O4 shell. The thickness of the shell is controlled from 0.5 to 3nm. An assembly of the core/shell nanoparticles shows a smooth magnetization transition under an external field, indicating effective exchange coupling between the FePt core and the oxide shell. The coercivity of the FePt /Fe3O4 particles depends on the volume ratio of the hard and soft phases, consistent with previous theoretical predictions. These bimagnetic core/shell nanoparticles represent a class of nanostructured magnetic materials with their properties tunable by varying the chemical composition and thickness of the coating materials.

  10. Horseradish peroxidase-immobilized magnetic mesoporous silica nanoparticles as a potential candidate to eliminate intracellular reactive oxygen species

    NASA Astrophysics Data System (ADS)

    Shen, Yajing; Zhang, Ye; Zhang, Xiang; Zhou, Xiuhong; Teng, Xiyao; Yan, Manqing; Bi, Hong

    2015-02-01

    Horseradish peroxidase-immobilized magnetic mesoporous silica nanoparticles (MMSNs-HRP) have been synthesized by a NHS/EDC coupling between the amino groups of horseradish peroxidase (HRP) and the carboxyl groups on the MMSNs surface. It is found that the immobilized HRP on MMSNs still retain high activity and the MMSNs-HRP can eliminate the reactive oxygen species (ROS) in Chinese hamster ovary (CHO) cells induced by the addition of H2O2 aqueous solution. Further, the fluorescent MMSN-HRP-CD nanoparticles have been prepared by attaching biocompatible, fluorescent carbon dots (CDs) to MMSNs-HRP. We have also investigated the effect of an applied magnetic field on cellular uptake of MMSNs-HRP-CDs and found that the internalization of MMSNs-HRP-CDs by CHO cells could be enhanced within 2 hours under the magnetic field. This work provides us with a novel and efficient method to eliminate ROS in living cells by using HRP-immobilized nanoparticles.Horseradish peroxidase-immobilized magnetic mesoporous silica nanoparticles (MMSNs-HRP) have been synthesized by a NHS/EDC coupling between the amino groups of horseradish peroxidase (HRP) and the carboxyl groups on the MMSNs surface. It is found that the immobilized HRP on MMSNs still retain high activity and the MMSNs-HRP can eliminate the reactive oxygen species (ROS) in Chinese hamster ovary (CHO) cells induced by the addition of H2O2 aqueous solution. Further, the fluorescent MMSN-HRP-CD nanoparticles have been prepared by attaching biocompatible, fluorescent carbon dots (CDs) to MMSNs-HRP. We have also investigated the effect of an applied magnetic field on cellular uptake of MMSNs-HRP-CDs and found that the internalization of MMSNs-HRP-CDs by CHO cells could be enhanced within 2 hours under the magnetic field. This work provides us with a novel and efficient method to eliminate ROS in living cells by using HRP-immobilized nanoparticles. Electronic supplementary information (ESI) available: TEM image of CDs, BET XRD

  11. Magnetic moment of a single metal nanoparticle determined from the Faraday effect

    NASA Astrophysics Data System (ADS)

    Szczytko, Jacek; Vaupotič, Nataša; Madrak, Karolina; Sznajder, Paweł; Górecka, Ewa

    2013-03-01

    Optical properties of a composite material made of ferromagnetic metal nanoparticles embedded in a dielectric host are studied. We constructed an effective dielectric tensor of the composite material taking into account the orientational distribution of nanoparticle magnetic moments in external magnetic field. A nonlinear dependence of the optical rotation on magnetic field resulting from the reorientation of nanoparticles is demonstrated. The theoretical findings were applied to the magneto-optical experimental data of cobalt ferromagnetic nanoparticles embedded in a dielectric liquid host. The dependence of the Faraday rotation on Co-based ferromagnetic nanoparticles was measured as a function of the external magnetic field, varying the size of nanoparticles and the wavelength of light. The proposed approach enables quantitative determination of the magnetic moment and the plasma frequency of a single nanoparticle, and from this the size of the nonmagnetic shell of magnetic nanoparticles.

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

    PubMed Central

    2011-01-01

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

  13. Exploiting Size-Dependent Drag and Magnetic Forces for Size-Specific Separation of Magnetic Nanoparticles

    PubMed Central

    Rogers, Hunter B.; Anani, Tareq; Choi, Young Suk; Beyers, Ronald J.; David, Allan E.

    2015-01-01

    Realizing the full potential of magnetic nanoparticles (MNPs) in nanomedicine requires the optimization of their physical and chemical properties. Elucidation of the effects of these properties on clinical diagnostic or therapeutic properties, however, requires the synthesis or purification of homogenous samples, which has proved to be difficult. While initial simulations indicated that size-selective separation could be achieved by flowing magnetic nanoparticles through a magnetic field, subsequent in vitro experiments were unable to reproduce the predicted results. Magnetic field-flow fractionation, however, was found to be an effective method for the separation of polydisperse suspensions of iron oxide nanoparticles with diameters greater than 20 nm. While similar methods have been used to separate magnetic nanoparticles before, no previous work has been done with magnetic nanoparticles between 20 and 200 nm. Both transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis were used to confirm the size of the MNPs. Further development of this work could lead to MNPs with the narrow size distributions necessary for their in vitro and in vivo optimization. PMID:26307980

  14. Magnetic Properties of Iron Oxide Nanoparticles Obtained by Laser Evaporation

    NASA Astrophysics Data System (ADS)

    Novoselova, Iu. P.; Samatov, O. M.; Kupriyanova, G. S.; Murzakaev, A. M.; Safronov, A. P.; Kurlyandskaya, G. V.

    2017-01-01

    The paper concentrates on a synthesis of spherical magnetic particles obtained by laser evaporation under various process conditions. Depending on the process conditions, which include the pressure in a process chamber, laser pulse duration, mean laser power, and the type of power gas, the stoichiometry of the material ranges from Fe 2.70 O 4 to Fe 2.84 O 4 , while the average diameter of nanoparticles ranges between 10-23 nm. The nanoparticles have an inverse spinel structure. In terms of the magnetic properties, the samples are a superparamagnetic ensemble. The spherical shape of the majority of nanoparticles as well as the existence of merely one magnetic phase are verified by the characteristics of microwave absorption. A relatively high saturation magnetization and a narrow size distribution of small nanoparticles obtained at 700 mmHg working pressure, 100 ms pulse duration, and 200 W laser power allow the authors to consider these conditions to be the most optimum for the nanopowder synthesis and recommend them for biological applications.

  15. 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

    2013-11-04

    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.

  16. 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.

  17. Tracking iron oxide nanoparticles in plant organs using magnetic measurements

    NASA Astrophysics Data System (ADS)

    Govea-Alcaide, E.; Masunaga, S. H.; De Souza, A.; Fajardo-Rosabal, L.; Effenberger, F. B.; Rossi, L. M.; Jardim, R. F.

    2016-10-01

    Common bean plants were grown in soil and irrigated with water solutions containing different concentrations of Fe_3{O}_4 nanoparticles (NPs) with a mean diameter close to 10 nm. No toxicity on plant growth has been detected as a consequence of Fe deficiency or excess in leaves. In order to track the Fe_3{O}_4 NPs, magnetization measurements were performed in soils and in three different dried organs of the plants: roots, stems, and leaves. Some magnetic features of both temperature and magnetic field dependence of magnetization M( T, H) arising from Fe_3{O}_4 NPs were identified in all the three organs of the plants. Based on the results of saturation magnetization M_s at 300 K, the estimated number of Fe_3{O}_4 NPs was found to increase from 2 to 3 times in leaves of common bean plants irrigated with solutions containing magnetic material. The combined results indicated that M( T, H) measurements, conducted in a wide range of temperature and applied magnetic fields up to 70 kOe, constitute a useful tool through which the uptake, translocation, and accumulation of magnetic nanoparticles by plant organs may be monitored and tracked.

  18. Strong and moldable cellulose magnets with high ferrite nanoparticle content.

    PubMed

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

    2014-11-26

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

  19. Core loss and magnetic susceptibility of superparamagnetic Fe nanoparticle assembly

    NASA Astrophysics Data System (ADS)

    Kin, Masane; Kura, Hiroaki; Ogawa, Tomoyuki

    2016-12-01

    Toroidal-shaped high-density Fe nanoparticle assemblies (FNAs) were fabricated by molding different sized Fe nanoparticles (NPs), and the effect of the magnetic behavior of the FNAs on the core loss and the magnetic susceptibility was investigated. An FNA with 4.3 nm diameter Fe NPs exhibits superparamagnetism at room temperature while an FNA with 6.4 nm diameter Fe NPs doesn't exhibit superparamagnetism at room temperature. AC magnetization curves at 1, 10 and 100 kHz were measured to evaluate the core loss of the toroidal-shaped FNAs. Both FNAs exhibited no significant eddy current loss, which suggests that surfactants on the NP surface effectively act to electrically insulate the NPs, and the NPs are not sintered together when the FNAs are molded. The AC magnetization curves had no hysteresis for the FNA with 4.3 nm diameter Fe NPs, i.e., the core loss was minimal for the superparamagnetic FNA. The magnetic susceptibility of the superparamagnetic FNA with 4.3 nm Fe NPs was 12 times higher than that estimated from Langevin theory due to the effect of strong magnetic dipole interaction. These results suggest that the superparamagnetic FNA has potential as a magnetic core material that exhibits low core loss and high magnetic susceptibility, even at high frequency.

  20. Nanosecond-resolved temperature measurements using magnetic nanoparticles.

    PubMed

    Xu, Wenbiao; Liu, Wenzhong; Zhang, Pu

    2016-05-01

    Instantaneous and noninvasive temperature measurements are important when laser thermotherapy or welding is performed. A noninvasive nanosecond-resolved magnetic nanoparticle (MNP) temperature measurement system is described in which a transient change in temperature causes an instantaneous change in the magnetic susceptibilities of the MNPs. These transient changes in the magnetic susceptibilities are rapidly recorded using a wideband magnetic measurement system with an upper frequency limit of 0.5 GHz. The Langevin function (the thermodynamic model characterizing the MNP magnetization process) is used to obtain the temperature information. Experiments showed that the MNP DC magnetization temperature-measurement system can detect a 14.4 ns laser pulse at least. This method of measuring temperature is likely to be useful for acquiring the internal temperatures of materials irradiated with lasers, as well as in other areas of research.

  1. Fluorescent magnetic nanoparticles with specific targeting functions for combinded targeting, optical imaging and magnetic resonance imaging.

    PubMed

    Chen, Yung-Chu; Chang, Wen-Hsiang; Wang, Shian-Jy; Hsieh, Wen-Yuan

    2012-01-01

    Superparamagnetic iron oxides nanoparticles possess specific magnetic properties to be an efficient contrast agent for magnetic resonance imaging (MRI) to enhance the detection and characterization of tissue lesions within the body. To endow specific properties to nanoparticles that can target cancer cells and prevent recognition by the reticuloendothelial system (RES), the surface of the nanoparticles was modified with folic-acid-conjugated poly(ethylene glycol) (FA-PEG). In this study, we investigated the multifunctional fluorescent magnetic nanoparticles (IOPFC) that can specifically target cancer cells and be monitored by both MRI and optical imaging. IOPFC consists of an iron oxide superparamagnetic nanoparticle conjugated with a layer of PEG, which was terminal modified with either Cypher5E or folic acid molecules. The core sizes of IOPFC nanoparticles are around 10 nm, which were visualized by transmission electron microscope (TEM). The hysteresis curves, generated with superconducting quantum interference device (SQUID) magnetometer analysis, demonstrated that IOPFC nanoparticles are superparamagnetic with insignificant hysteresis. IOPFC displays higher intracellular uptake into KB and MDA-MB-231 cells due to the over-expressed folate receptor. This result is confirmed by laser confocal scanning microscopy (LCSM) and atomic flow cytometry. Both in vitro and in vivo MRI studies show better IOPFC uptake by the KB cells (folate positive) than the HT1080 cells (folate negative) and, hence, stronger T 2-weighted signals enhancement. The in vivo fluorescent image recorded at 20 min post injection show strong fluorescence from IOPFC which can be observed around the tumor region. This multifunctional nanoparticle can assess the potential application of developing a magnetic nanoparticle system that combines tumor targeting, as well as MRI and optical imaging.

  2. Magnetic Properties of Nanoparticle Matrix Composites

    DTIC Science & Technology

    2015-06-02

    been optimized for each composition of Fe-Pt and their spin isomers have been studied to find the magnetic moments of the lowest energy structures ...numbers in brackets below the structures refer to the energy (eV) relative to the lowest energy isomer and the magnetic moment (µB). Red (blue) balls...Approved for public release; distribution is unlimited. Distribution is unlimited structures . The magnetic moments increase systematically by 4µB when a

  3. Enhanced dielectric and magnetic properties of polystyrene added CoFe2O4 magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Vadivel, M.; Babu, R. Ramesh; Ramamurthi, K.; Arivanandhan, M.

    2017-03-01

    In this work, a facile chemical synthesis of polystyrene (PS) added cobalt ferrite (CoFe2O4) magnetic nanoparticles by co-precipitation method is reported and the role of PS concentrations (1, 2, 3, 4 and 5 wt%) on the structural, morphological, dielectric and magnetic properties of CoFe2O4 nanoparticles is investigated. Formation of single phase cubic inverse spinel structure is confirmed by X-ray diffraction and Raman spectral analyses. Transmission electron microscopy studies show that the size of CoFe2O4 nanoparticles can be controlled by varying of PS concentration. Dielectric constant is enhanced due to increase in the PS concentrations in CoFe2O4 nanoparticles. Vibrating sample magnetometer measurements elucidate the enhanced saturation magnetization, coercivity and remanent magnetization in 1, 2 and 3 wt% of PS added CoFe2O4 nanoparticles. Hence the results obtained in this work evidently show that the addition of PS as a surfactant in the synthesis of CoFe2O4 nanoparticles remarkably modify the size of the particles.

  4. Magnetic nanoparticles and nanocomposites for remote controlled therapies.

    PubMed

    Hauser, Anastasia K; Wydra, Robert J; Stocke, Nathanael A; Anderson, Kimberly W; Hilt, J Zach

    2015-12-10

    This review highlights the state-of-the-art in the application of magnetic nanoparticles (MNPs) and their composites for remote controlled therapies. Novel macro- to nano-scale systems that utilize remote controlled drug release due to actuation of MNPs by static or alternating magnetic fields and magnetic field guidance of MNPs for drug delivery applications are summarized. Recent advances in controlled energy release for thermal therapy and nanoscale energy therapy are addressed as well. Additionally, studies that utilize MNP-based thermal therapy in combination with other treatments such as chemotherapy or radiation to enhance the efficacy of the conventional treatment are discussed.

  5. Synthesis, Structural, Electrical and Magnetic Studies of Ni- Ferrite Nanoparticles

    NASA Astrophysics Data System (ADS)

    Godbole, Bhavana; Badera, Nitu; Shrivastava, S. B.; Jain, Deepti; Chandra, L. S. Sharath; Ganesan, V.

    Mono-dispersed NiFe2O4 nanoparticles have been synthesized using a stable ferric salt of FeCl3 with co-precipitation technique, for study of their structural, morphological and magnetic properties. The XRD pattern conforms the formation of FCC structure with the lattice constant 8.31Ao. The crystallite size was found to increase with the bath temperature ranging from 33 nm to 55 nm. The AFM results revealed that uniform disc shaped particles were obtained. The resistivity measurements show a metal like to semiconductor transition, which depends on the size of the grains. The magnetic study reveals that saturation magnetization increases with the grain thickness.

  6. Probing magnetic and electric optical responses of silicon nanoparticles

    SciTech Connect

    Permyakov, Dmitry; Sinev, Ivan; Markovich, Dmitry; Samusev, Anton; Belov, Pavel; Ginzburg, Pavel; Valuckas, Vytautas; Kuznetsov, Arseniy I.; Luk'yanchuk, Boris S.; Miroshnichenko, Andrey E.; Neshev, Dragomir N.; Kivshar, Yuri S.

    2015-04-27

    We study experimentally both magnetic and electric optically induced resonances of silicon nanoparticles by combining polarization-resolved dark-field spectroscopy and near-field scanning optical microscopy measurements. We reveal that the scattering spectra exhibit strong sensitivity of electric dipole response to the probing beam polarization and attribute the characteristic asymmetry of measured near-field patterns to the excitation of a magnetic dipole mode. The proposed experimental approach can serve as a powerful tool for the study of photonic nanostructures possessing both electric and magnetic optical responses.

  7. Chemically Functional Alkanethiol Derivitized Magnetic Nanoparticles

    DTIC Science & Technology

    2003-01-01

    agents in medical imaging technologies7, and ’spintronics’ 8 (i.e., spin-based data transfer and storage). For example, Co and FePt nanoparticles have been...with a personal computer. Pt microelectrodes (25pin diameter) were created by flame-sealing Pt microwire (Alfa Aesar) in glass capillaries. The sealed

  8. Dynamics of nanoparticle agglomeration in a magnetic fluid in a varying magnetic field

    NASA Astrophysics Data System (ADS)

    Usanov, D. A.; Postel'ga, A. E.; Bochkova, T. S.; Gavrilin, V. N.

    2016-03-01

    It is found that the dependence of the magnetic nanoparticle agglomerate length in a magnetic fluid on the applied magnetic field has three characteristic segments: a substantial increase in the agglomerate length with the magnetic field in the range of weak fields, a segment with an insignificant increase in the average length of agglomerates upon an increase in the field, and a sharp increase in the agglomerate length with a further increase in the field. It is shown that the agglomerate length increases in the range of strong magnetic fields due to a decrease in the spacing between adjacent agglomerates down to their complete coalescence. The total number of agglomerates decreases thereby.

  9. Rapid and Efficient Protein Digestion using Trypsin Coated Magnetic Nanoparticles under Pressure Cycles

    SciTech Connect

    Lee, Byoungsoo; Lopez-Ferrer, Daniel; Kim, Byoung Chan; Na, Hyon Bin; Park, Yong Il; Weitz, Karl K.; Warner, Marvin G.; Hyeon, Taeghwan; Lee, Sang-Won; Smith, Richard D.; Kim, Jungbae

    2011-01-01

    Trypsin-coated magnetic nanoparticles (EC-TR/NPs), prepared via a simple crosslinking of the enzyme to magnetic nanoparticles, were highly stable and could be easily captured using a magnet after the digestion was complete. EC-TR/NPs showed a negligible loss of trypsin activity after multiple uses and continuous shaking, while a control sample of covalently-attached trypsin on NPs resulted in a rapid inactivation under the same conditions due to the denaturation and autolysis of trypsin. Digestions were carried out on a single model protein, a five protein mixture, and a whole mouse brain proteome, and also compared for digestion at atmospheric pressure and 37 ºC for 12 h, and in combination with pressure cycling technology (PCT) at room temperature for 1 min. In all cases, the EC-TR/NPs performed equally as well or better than free trypsin in terms of the number of peptide/protein identifications and reproducibility across technical replicates. However, the concomitant use of EC-TR/NPs and PCT resulted in very fast (~1 min) and more reproducible digestions.

  10. Direct electrochemistry of Phanerochaete chrysosporium cellobiose dehydrogenase covalently attached onto gold nanoparticle modified solid gold electrodes.

    PubMed

    Matsumura, Hirotoshi; Ortiz, Roberto; Ludwig, Roland; Igarashi, Kiyohiko; Samejima, Masahiro; Gorton, Lo

    2012-07-24

    Achieving efficient electrochemical communication between redox enzymes and various electrode materials is one of the main challenges in bioelectrochemistry and is of great importance for developing electronic applications. Cellobiose dehydrogenase (CDH) is an extracellular flavocytochrome composed of a catalytic FAD containing dehydrogenase domain (DH(CDH)), a heme b containing cytochrome domain (CYT(CDH)), and a flexible linker region connecting the two domains. Efficient direct electron transfer (DET) of CDH from the basidiomycete Phanerochaete chrysosporium (PcCDH) covalently attached to mixed self-assembled monolayer (SAM) modified gold nanoparticle (AuNP) electrode is presented. The thiols used were as follows: 4-aminothiophenol (4-ATP), 4-mercaptobenzoic acid (4-MBA), 4-mercaptophenol (4-MP), 11-mercapto-1-undecanamine (MUNH(2)), 11-mercapto-1-undecanoic acid (MUCOOH), and 11-mercapto-1-undecanol (MUOH). A covalent linkage between PcCDH and 4-ATP or MUNH(2) in the mixed SAMs was formed using glutaraldehyde as cross-linker. The covalent immobilization and the surface coverage of PcCDH were confirmed with surface plasmon resonance (SPR). To improve current density, AuNPs were cast on the top of polycrystalline gold electrodes. For all the immobilized PcCDH modified AuNPs electrodes, cyclic voltammetry exhibited clear electrochemical responses of the CYT(CDH) with fast electron transfer (ET) rates in the absence of substrate (lactose), and the formal potential was evaluated to be +162 mV vs NHE at pH 4.50. The standard ET rate constant (k(s)) was estimated for the first time for CDH and was found to be 52.1, 59.8, 112, and 154 s(-1) for 4-ATP/4-MBA, 4-ATP/4-MP, MUNH(2)/MUCOOH, and MUNH(2)/MUOH modified electrodes, respectively. At all the mixed SAM modified AuNP electrodes, PcCDH showed DET only via the CYT(CDH). No DET communication between the DH(CDH) domain and the electrode was found. The current density for lactose oxidation was remarkably increased by

  11. Magnetic nanoparticle transport within flowing blood and into surrounding tissue

    PubMed Central

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

    2011-01-01

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

  12. Size and compositionally controlled manganese ferrite nanoparticles with enhanced magnetization

    NASA Astrophysics Data System (ADS)

    Vamvakidis, K.; Sakellari, D.; Angelakeris, M.; Dendrinou-Samara, C.

    2013-06-01

    A facile solvothermal approach was used to synthesize stable, superparamagnetic manganese ferrite nanoparticles with relatively small sizes (<10 nm) and enhanced magnetic features. Tetraethylene glycol has been used in all the syntheses as a biocompatible and stabilizing agent. By varying the oxidation state of manganese precursor, Mn(acac)2 to Mn(acac)3, different sizes, 8 and 5 nm, of MnFe2O4 nanoparticles were obtained respectively, while by tailoring the synthetic conditions iron-rich Mn0.77Fe2.23O4 nanoparticles have been isolated with identical sizes and enhanced saturation magnetization. The magnetization values increased from 58.2 to 68.3 Am2/kg and from 53.3 to 60.2 Am2/kg for the nanoparticles of 8 and 5 nm, respectively. Blocking temperature ( T B), ranging from 80 to 180 K, and anisotropy constant ( K eff), ranging from 1.5 × 105 to 4.9 × 105 J/m3, were found higher for the iron-rich samples and associated with size and composition effects.

  13. Magnetic properties of iron nanoparticles prepared by exploding wire technique.

    PubMed

    Alqudami, Abdullah; Annapoorni, S; Lamba, Subhalakshmi; Kothari, P C; Kotnala, R K

    2007-06-01

    Nanoparticles of iron were prepared in distilled water using very thin iron wires and sheets, by the electro-exploding wire technique. Transmission electron microscopy reveals the size of the nanoparticles to be in the range 10 to 50 nm. However, particles of different sizes can be segregated by using ultrahigh centrifuge. X-ray diffraction studies confirm the presence of the cubic phase of iron. These iron nanoparticles were found to exhibit fluorescence in the visible region in contrast to the normal bulk material. The room temperature hysteresis measurements upto a field of 1.0 tesla were performed on a suspension of iron particles in the solution as well as in the powders obtained by filtration. The hysteresis loops indicate that the particles are superparamagnetic in nature. The saturation magnetizations was approximately 60 emu/gm. As these iron particles are very sensitive to oxygen a coating of non-magnetic iron oxide tends to form around the particles giving it a core-shell structure. The core particle size is estimated theoretically from the magnetization measurements. Suspensions of iron nanoparticles in water have been proposed to be used as an effective decontaminant for ground water.

  14. Magnetic manipulation of superparamagnetic nanoparticles in a microfluidic system for drug delivery applications

    NASA Astrophysics Data System (ADS)

    Agiotis, L.; Theodorakos, I.; Samothrakitis, S.; Papazoglou, S.; Zergioti, I.; Raptis, Y. S.

    2016-03-01

    Magnetic nanoparticles (MNPs), such as superparamagnetic iron oxide nanoparticles (SPIONS), have attracted major interest, due to their small size and unique magnetic properties, for drug delivery applications. In this context, iron oxide nanoparticles of magnetite (Fe3O4) (150 nm magnetic core diameter), were used as drug carriers, aiming to form a magnetically controlled nano-platform. The navigation capabilities of the iron oxide nanoparticles in a microfluidic channel were investigated by simulating the magnetic field and the magnetic force applied on the magnetic nanoparticles inside a microfluidic chip. The simulations have been performed using finite element method (ANSY'S software). The optimum setup which intends to simulate the magnetic navigation of the nanoparticles, by the use of MRI-type fields, in the human circulatory system, consists of two parallel permanent magnets to produce a homogeneous magnetic field, in order to ensure the maximum magnetization of the magnetic nanoparticles, an electromagnet for the induction of the magnetic gradients and the creation of the magnetic force and a microfluidic setup so as to simulate the blood flow inside the human blood vessels. The magnetization of the superparamagnetic nanoparticles and the consequent magnetic torque developed by the two permanent magnets, together with the mutual interactions between the magnetized nanoparticles lead to the creation of rhabdoid aggregates in the direction of the homogeneous field. Additionally, the magnetic gradients introduced by the operation of the electromagnet are capable of directing the aggregates, as a whole, to the desired direction. By removing the magnetic fields, the aggregates are disrupted, due to the super paramagnetic nature of the nanoparticles, avoiding thus the formation of undesired thrombosis.

  15. Magnetically enhanced high-specificity virus detection using bio-activated magnetic nanoparticles with antibodies as labeling markers.

    PubMed

    Yang, S Y; Wang, W C; Lan, C B; Chen, C H; Chieh, J J; Horng, H E; Hong, Chin-Yih; Yang, H C; Tsai, C P; Yang, C Y; Cheng, I C; Chung, W C

    2010-03-01

    This study describes magnetically driven suppression of cross-reactions among molecules. First, the magnetic nanoparticles are coated with bio-probes and dispersed in liquid. The bio-probes can then bind with homologous or heterologous bio-targets. When alternating-current (ac) magnetic fields are applied, magnetic nanoparticles rotate driven by ac magnetic fields. Thus, the bio-targets bound on the surface of magnetic nanoparticles experience a centrifugal force. The centrifugal force can be manipulated by adjusting the angular frequency of the rotating magnetic nanoparticles. The angular frequency is determined by the applied ac magnetic field frequency. Since the binding force for good binding is much higher than that of poor binding, frequency manipulation is needed for the centrifugal force to be higher than the poor-binding force but lower than the good-binding force. Therefore, poor binding which contributes to cross reactions between molecules can be suppressed efficiently by control of the ac magnetic field frequency.

  16. Origin of reduced magnetization and domain formation in small magnetite nanoparticles

    PubMed Central

    Nedelkoski, Zlatko; Kepaptsoglou, Demie; Lari, Leonardo; Wen, Tianlong; Booth, Ryan A.; Oberdick, Samuel D.; Galindo, Pedro L.; Ramasse, Quentin M.; Evans, Richard F. L.; Majetich, Sara; Lazarov, Vlado K.

    2017-01-01

    The structural, chemical, and magnetic properties of magnetite nanoparticles are compared. Aberration corrected scanning transmission electron microscopy reveals the prevalence of antiphase boundaries in nanoparticles that have significantly reduced magnetization, relative to the bulk. Atomistic magnetic modelling of nanoparticles with and without these defects reveals the origin of the reduced moment. Strong antiferromagnetic interactions across antiphase boundaries support multiple magnetic domains even in particles as small as 12–14 nm. PMID:28393876

  17. Characterizing and imaging magnetic nanoparticles by optical magnetometry

    NASA Astrophysics Data System (ADS)

    Weis, A.; Colombo, S.; Dolgovskiy, V.; Grujić, Z. D.; Lebedev, V.; Zhang, J.

    2017-01-01

    We review our ongoing work on deploying optical (atomic) magnetometry for measuring the magnetic response of magnetic nanoparticle (MNP) samples, yielding MNP size distributions, and other sample parameters like Néel relaxation time τ, saturation magnetisation Ms , anisotropy constant K and magnetic susceptibility χ. We address magnetorelaxation (MRX) signals, in which the decaying magnetisation M(t) following a magnetising pulse is recorded by a single atomic magnetometer or by a novel magnetic source imaging camera (MSIC) allowing spatially resolved MRX studies of distributed MNP samples. We further show that optical magnetometers can be used for a direct measurement of the M(H) and dM/dH(H) dependencies of MNP samples, the latter forming the basis for an optical magnetometer implementation of the MPI (Magnetic Particle Imaging) method. All experiments are in view of developing biomedical imaging modalities.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  19. Surface functionalized magnetic nanoparticles for cancer therapy applications

    NASA Astrophysics Data System (ADS)

    Wydra, Robert John

    Despite recent advances, cancer remains the second leading cause of deaths in the United States. Magnetic nanoparticles have found various applications in cancer research as drug delivery platforms, enhanced contrast agents for improved diagnostic imaging, and the delivery of thermal energy as standalone therapy. Iron oxide nanoparticles absorb the energy from an alternating magnetic field and convert it into heat through Brownian and Neel relaxations. To better utilize magnetic nanoparticles for cancer therapy, surface functionalization is essential for such factors as decreasing cytotoxicity of healthy tissue, extending circulation time, specific targeting of cancer cells, and manage the controlled delivery of therapeutics. In the first study, iron oxide nanoparticles were coated with a poly(ethylene glycol) (PEG) based polymer shell. The PEG coating was selected to prevent protein adsorption and thus improve circulation time and minimize host response to the nanoparticles. Thermal therapy application feasibility was demonstrated in vitro with a thermoablation study on lung carcinoma cells. Building on the thermal therapy demonstration with iron oxide nanoparticles, the second area of work focused on intracellular delivery. Nanoparticles can be appropriately tailored to enter the cell and deliver energy on the nanoscale eliminating individual cancer cells. The underlying mechanism of action is still under study, and we were interested in determining the role of reactive oxygen species (ROS) catalytically generated from the surface of iron oxide nanoparticles in this measured cytotoxicity. When exposed to an AMF, the nanoscale heating effects are capable of enhancing the Fenton-like generation of ROS determined through a methylene blue degradation assay. To deliver this enhanced ROS effect to cells, monosaccharide coated nanoparticles were developed and successfully internalized by colon cancer cell lines. Upon AMF exposure, there was a measured increase in

  20. MnZnFe nanoparticles for self-controlled magnetic hyperthermia

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  1. Intrinsic Magnetism and Collective Magnetic Properties of Size-Selected Nanoparticles

    NASA Astrophysics Data System (ADS)

    Antoniak, C.; Friedenberger, N.; Trunova, A.; Meckenstock, R.; Kronast, F.; Fauth, K.; Farle, M.; Wende, H.

    Using size-selected spherical FePt nanoparticles and cubic Fe/Fe-oxide nanoparticles as examples, we discuss the recent progress in the determination of static and dynamic properties of nanomagnets. Synchroton radiation-based characterisation techniques in combination with detailed structural, chemical and morphological investigations by transmission and scanning electron microscopy allow the quantitative correlation between element-specific magnetic response and spin structure on the one hand and shape, crystal and electronic structure of the particles on the other hand. Examples of measurements of element-specific hysteresis loops of single 18 nm sized nanocubes are discussed. Magnetic anisotropy of superparamagnetic ensembles and their dynamic magnetic response are investigated by ferromagnetic resonance as a function of temperature at different microwave frequencies. Such investigations allow the determination of the magnetic relaxation and the extraction of the average magnetic anisotropy energy density of the individual particles.

  2. Frequency-Dependent Properties of Magnetic Nanoparticle Crystals

    SciTech Connect

    Majetich, Sara

    2016-05-17

    In the proposed research program we will investigate the time- and frequency-dependent behavior of ordered nanoparticle assemblies, or nanoparticle crystals. Magnetostatic interactions are long-range and anisotropic, and this leads to complex behavior in nanoparticle assemblies, particularly in the time- and frequency-dependent properties. We hypothesize that the high frequency performance of composite materials has been limited because of the range of relaxation times; if a composite is a dipolar ferromagnet at a particular frequency, it should have the advantages of a single phase material, but without significant eddy current power losses. Arrays of surfactant-coated monodomain magnetic nanoparticles can exhibit long-range magnetic order that is stable over time. The magnetic domain size and location of domain walls is governed not by structural grain boundaries but by the shape of the array, due to the local interaction field. Pores or gaps within an assembly pin domain walls and limit the domain size. Measurements of the magnetic order parameter as a function of temperature showed that domains can exist at high temoerature, and that there is a collective phase transition, just as in an exchange-coupled ferromagnet. Dipolar ferromagnets are not merely of fundamental interest; they provide an interesting alternative to exchange-based ferromagnets. Dipolar ferromagnets made with high moment metallic particles in an insulating matrix could have high permeability without large eddy current losses. Such nanocomposites could someday replace the ferrites now used in phase shifters, isolators, circulators, and filters in microwave communications and radar applications. We will investigate the time- and frequency-dependent behavior of nanoparticle crystals with different magnetic core sizes and different interparticle barrier resistances, and will measure the magnetic and electrical properties in the DC, low frequency (0.1 Hz - 1 kHz), moderate frequency (10 Hz - 500

  3. 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.

  4. Ultrathin Interface Regime of Core-Shell Magnetic Nanoparticles for Effective Magnetism Tailoring.

    PubMed

    Moon, Seung Ho; Noh, Seung-Hyun; Lee, Jae-Hyun; Shin, Tae-Hyun; Lim, Yongjun; Cheon, Jinwoo

    2017-02-08

    The magnetic exchange coupling interaction between hard and soft magnetic phases has been important for tailoring nanoscale magnetism, but spin interactions at the core-shell interface have not been well studied. Here, we systematically investigated a new interface phenomenon termed enhanced spin canting (ESC), which is operative when the shell thickness becomes ultrathin, a few atomic layers, and exhibits a large enhancement of magnetic coercivity (HC). We found that ESC arises not from the typical hard-soft exchange coupling but rather from the large magnetic surface anisotropy (KS) of the ultrathin interface. Due to this large increase in magnetism, ultrathin core-shell nanoparticles overreach the theoretical limit of magnetic energy product ((BH)max) and exhibit one of the largest values of specific loss power (SLP), which testifies to their potential capability as an effective mediator of magnetic energy conversion.

  5. Multifunctional clickable and protein-repellent magnetic silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Estupiñán, Diego; Bannwarth, Markus B.; Mylon, Steven E.; Landfester, Katharina; Muñoz-Espí, Rafael; Crespy, Daniel

    2016-01-01

    Silica nanoparticles are versatile materials whose physicochemical surface properties can be precisely adjusted. Because it is possible to combine several functionalities in a single carrier, silica-based materials are excellent candidates for biomedical applications. However, the functionality of the nanoparticles can get lost upon exposure to biological media due to uncontrolled biomolecule adsorption. Therefore, it is important to develop strategies that reduce non-specific protein-particle interactions without losing the introduced surface functionality. Herein, organosilane chemistry is employed to produce magnetic silica nanoparticles bearing differing amounts of amino and alkene functional groups on their surface as orthogonally addressable chemical functionalities. Simultaneously, a short-chain zwitterion is added to decrease the non-specific adsorption of biomolecules on the nanoparticles surface. The multifunctional particles display reduced protein adsorption after incubation in undiluted fetal bovine serum as well as in single protein solutions (serum albumin and lysozyme). Besides, the particles retain their capacity to selectively react with biomolecules. Thus, they can be covalently bio-functionalized with an antibody by means of orthogonal click reactions. These features make the described multifunctional silica nanoparticles a promising system for the study of surface interactions with biomolecules, targeting, and bio-sensing.Silica nanoparticles are versatile materials whose physicochemical surface properties can be precisely adjusted. Because it is possible to combine several functionalities in a single carrier, silica-based materials are excellent candidates for biomedical applications. However, the functionality of the nanoparticles can get lost upon exposure to biological media due to uncontrolled biomolecule adsorption. Therefore, it is important to develop strategies that reduce non-specific protein-particle interactions without losing the

  6. 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.

  7. GMR sensors and magnetic nanoparticles for immuno-chromatographic assays

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  8. [Thermal therapy of prostate cancer using magnetic nanoparticles].

    PubMed

    Johannsen, Manfred; Gneveckow, Uwe; Taymoorian, Kasra; Cho, Chie Hee; Thiesen, Burghard; Scholz, Regina; Waldöfner, Norbert; Loening, Stefan A; Wust, Peter; Jordan, Andreas

    2007-06-01

    A novel method of interstitial heating using magnetic nanoparticles and a direct injection technique has been evaluated in human cancers in recent clinical trials. In prostate cancer, this approach was investigated in two separate phase-I-studies, employing magnetic nanoparticle thermotherapy alone and in combination with permanent seed brachytherapy. The feasibility and good tolerability was shown in both trials, using the first prototype of a magnetic field applicator. As with any other heating technique, this novel approach requires specific tools for planning, quality control and thermal monitoring, based on appropriate imaging and modelling techniques. In these first clinical trials, a newly developed method for planning and non-invasive calculations of the 3-dimensional temperature distribution based on computed tomography could be validated. Limiting factors of this approach at present are patient discomfort at high magnetic field strengths and suboptimal intratumoral distribution of nanoparticles. Until these limitations will be overcome and thermal ablation can safely be applied as a monotherapy, this treatment modality is being evaluated in combination with irradiation in patients with localized prostate cancer.

  9. Iron oxide nanoparticles for magnetically assisted patterned coatings

    NASA Astrophysics Data System (ADS)

    Dodi, Gianina; Hritcu, Doina; Draganescu, Dan; Popa, Marcel I.

    2015-08-01

    Iron oxide nanoparticles able to magnetically assemble during the curing stage of a polymeric support to create micro-scale surface protuberances in a controlled manner were prepared and characterized. The bare Fe3O4 particles were obtained by two methods: co-precipitation from an aqueous solution containing Fe3+/Fe2+ ions with a molar ratio of 2:1 and partial oxidation of ferrous ions in alkaline conditions. The products were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and magnetization measurement. They were subsequently functionalized using oleic acid, sodium oleate, or non-ionic surfactant mixtures with various hydrophilic to lipophilic balance (HLB) values. Composite nanoparticle-polymer films prepared by spraying were deposited and cured by drying on glass slides under a static magnetic field in the range of 1.5-5.5 mT. Magnetic field generated surface roughness was evidenced by optical and scanning electron microscopy. The optimum hierarchical patterning was obtained with the nanoparticles produced by partial oxidation and functionalized with hydrophobic surfactants. Possible applications may include ice-phobic composite coatings.

  10. Carbodiimide-mediated immobilization of serratiopeptidase on amino-, carboxyl-functionalized magnetic nanoparticles and characterization for target delivery

    NASA Astrophysics Data System (ADS)

    Kumar, Sandeep; Jana, Asim K.; Maiti, Mithu; Dhamija, Isha

    2014-02-01

    A hybrid biomaterial of serratiopeptidase enzyme was prepared with magnetic nanoparticles (MNPs) via carboxyl and amino-functionalization and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) for direct immobilization. The average size of prepared MNPs was found to be 15.05 ± 3.06 nm. Attachment of amino and carboxyl groups was confirmed by Fourier transform infrared spectroscopy. X-ray diffraction confirmed the purity and phase integrity of Fe3O4. The MNPs and enzyme-loaded-MNPs (EMNPs) were of saturation magnetization 58 and 50 emu g-1, respectively. Thermogravimetric analysis of EDC-MNPs and EMNPs showed the presence of organic coating over MNPs. Serratiopeptidase immobilized on amino-functionalized magnetic nanoparticles showed loss of enzyme activity due to crosslinking of enzyme, while serratiopeptidase immobilized on carboxyl-functionalized magnetic nanoparticles was better and gave 115.78 mg protein g-1 MNPs, enzyme loading 168.32 U g-1 MNPs at optimized MNPs-to-enzyme ratio 1.0 mg mg-1. In vitro and in vivo studies showed that EMNPs with magnetic targeting is more effective in drug permeation and reduction in edema than free enzyme.

  11. Numerical simulation of magnetic nanoparticles targeting in a bifurcation vessel

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  12. Stimuli-responsive magnetic nanoparticles for monoclonal antibody purification.

    PubMed

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

    2013-06-01

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

  13. Anomalous magnetic properties of mechanically milled cobalt oxide nanoparticles.

    PubMed

    Mishra, S R; Dubenko, I; Losby, J; Ghosh, l K; Khan, M; Ali, N

    2005-12-01

    Defect induced magnetic properties of CoO nanoparticles produced via mechanical ball milling have been assessed by detailed magnetic measurements. A progressive decrease in the particle size and a concomitant increase in the induced strain have been observed with the milling times. The mechanically milled nanoparticles of CoO exhibit anomalous magnetic properties such as FM hysteresis when compared with the unmilled CoO sample. The presence of weak ferromagnetism, with a highest value of magnetization of 0.532 emu/g at 10 K in the 100 h milled sample, is attributed to the uncompensated surface spins resulting from induced surface defects via mechanical milling. The ZFC coercive force, measured at 10 K, increases with milling time reaching a maximum value of 1066 Oe for the 100 h milled sample. The temperature dependent field-cooled (FC) and zero-field-cooled (ZFC) magnetic measurements indicate a presence of an exchange bias field arising from uncompensated moments generated by mechanical strain and the antiferromagnetic (AFM) core. The exchange bias field measured at 10 K reaches a value 210 Oe for the 50 h milled sample and decreases upon prolonged milling. The exchange bias field vanishes at a temperature approximately 200 K, a temperature much lower than the Neel temperature of CoO (TN approximately 291 K). The observed anomalous magnetic behavior of CoO could be interpreted in terms of the exchanged bias FM-AFM model.

  14. Structural and Magnetic Response in Bimetallic Core/Shell Magnetic Nanoparticles

    PubMed Central

    Nairan, Adeela; Khan, Usman; Iqbal, Munawar; Khan, Maaz; Javed, Khalid; Riaz, Saira; Naseem, Shahzad; Han, Xiufeng

    2016-01-01

    Bimagnetic monodisperse CoFe2O4/Fe3O4 core/shell nanoparticles have been prepared by solution evaporation route. To demonstrate preferential coating of iron oxide onto the surface of ferrite nanoparticles X-ray diffraction (XRD), High resolution transmission electron microscope (HR-TEM) and Raman spectroscopy have been performed. XRD analysis using Rietveld refinement technique confirms single phase nanoparticles with average seed size of about 18 nm and thickness of shell is 3 nm, which corroborates with transmission electron microscopy (TEM) analysis. Low temperature magnetic hysteresis loops showed interesting behavior. We have observed large coercivity 15.8 kOe at T = 5 K, whereas maximum saturation magnetization (125 emu/g) is attained at T = 100 K for CoFe2O4/Fe3O4 core/shell nanoparticles. Saturation magnetization decreases due to structural distortions at the surface of shell below 100 K. Zero field cooled (ZFC) and Field cooled (FC) plots show that synthesized nanoparticles are ferromagnetic till room temperature and it has been noticed that core/shell sample possess high blocking temperature than Cobalt Ferrite. Results indicate that presence of iron oxide shell significantly increases magnetic parameters as compared to the simple cobalt ferrite. PMID:28335200

  15. Synthesis and Characteristics of FePt Nanoparticle Films Under In Situ-Applied Magnetic Field.

    PubMed

    Qian, Xu; Gao, Mo-Yun; Li, Ai-Dong; Zhou, Xiao-Yu; Liu, Xiao-Jie; Cao, Yan-Qiang; Li, Chen; Wu, Di

    2016-12-01

    In situ external magnetic field was applied during the synthesis of FePt nanoparticles via a chemical solution method. FePt nanoparticle films were prepared on Si by a drop-coating method with and without a magnetic field. Annealing at 700 °C in reductive atmosphere was explored to obtain ferromagnetic FePt L10 phase. The effect of in situ-applied magnetic field on the structure, morphology, and magnetic properties of FePt nanoparticle films was characterized. It is found that the applied magnetic field during the chemical synthesis of FePt nanoparticles plays a key role in the crystallinity and magnetic property of FePt nanoparticle films. As-synthesized FePt nanoparticles under the magnetic field are monodispersed and can be self-assembled over a larger area by a dropping method. The applied magnetic field during the synthesis of FePt nanoparticles not only significantly improves the nanoparticles' c-axis preferred orientation but also benefits the phase transition of FePt nanoparticles from face-centered cubic to face-centered tetragonal structure during the annealing process. The FePt nanoparticle films derived under magnetic field also show some magnetic anisotropy.

  16. Synthesis and Characteristics of FePt Nanoparticle Films Under In Situ-Applied Magnetic Field

    NASA Astrophysics Data System (ADS)

    Qian, Xu; Gao, Mo-Yun; Li, Ai-Dong; Zhou, Xiao-Yu; Liu, Xiao-Jie; Cao, Yan-Qiang; Li, Chen; Wu, Di

    2016-07-01

    In situ external magnetic field was applied during the synthesis of FePt nanoparticles via a chemical solution method. FePt nanoparticle films were prepared on Si by a drop-coating method with and without a magnetic field. Annealing at 700 °C in reductive atmosphere was explored to obtain ferromagnetic FePt L10 phase. The effect of in situ-applied magnetic field on the structure, morphology, and magnetic properties of FePt nanoparticle films was characterized. It is found that the applied magnetic field during the chemical synthesis of FePt nanoparticles plays a key role in the crystallinity and magnetic property of FePt nanoparticle films. As-synthesized FePt nanoparticles under the magnetic field are monodispersed and can be self-assembled over a larger area by a dropping method. The applied magnetic field during the synthesis of FePt nanoparticles not only significantly improves the nanoparticles' c-axis preferred orientation but also benefits the phase transition of FePt nanoparticles from face-centered cubic to face-centered tetragonal structure during the annealing process. The FePt nanoparticle films derived under magnetic field also show some magnetic anisotropy.

  17. 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.

  18. Visualization of pulsatile flow for magnetic nanoparticle based therapies

    NASA Astrophysics Data System (ADS)

    Wentzel, Andrew; Yecko, Philip

    2015-11-01

    Pulsatile flow of blood through branched, curved, stenosed, dilated or otherwise perturbed vessels is more complex than flow through a straight, uniform and rigid tube. In some magnetic hyperthermia and magnetic chemo-therapies, localized regions of magnetic nanoparticle laden fluid are deliberately formed in blood vessels and held in place by magnetic fields. The effect of localized magnetic fluid regions on blood flow and the effect of the pulsatile blood flow on such magnetic fluid regions are poorly understood and difficult to examine in vivo or by numerical simulation. We present a laboratory model that facilitates both dye tracer and particle imaging velocimetry (PIV) studies of pulsatile flow of water through semi-flexible tubes in the presence of localized magnetic fluid regions. Results on the visualization of flows over a range of Reynolds and Womersley numbers and for several different (water-based) ferrofluids are compared for straight and curved vessels and for different magnetic localization strategies. These results can guide the design of improved magnetic cancer therapies. Support from the William H. Sandholm Program of Cooper Union's Kanbar Center for Biomedical Engineering is gratefully acknowledged.

  19. Bio-Magnetics Interfacing Concepts: A Microfluidic System Using Magnetic Nanoparticles for Quantitative Detection of Biological Species

    DTIC Science & Technology

    2007-11-02

    retinal damage model. B) Retinal neuroprotection by an LAU compound. C) Localization of [3H]leucine- labeled super paramagnetic nanoparticles and directed...exposed to five hours of light and returned to darkness until retinas were analyzed. [3H]leucine binding to super paramagnetic nanoparticles Ten-nm...diameter super paramagnetic nanoparticles were fabricated for us by CAMD and amino groups attached to the surfaces. Under the guidance of CAMD, we

  20. Fluorochrome-functionalized magnetic nanoparticles for high-sensitivity monitoring of the polymerase chain reaction by magnetic resonance.

    PubMed

    Alcantara, David; Guo, Yanyan; Yuan, Hushan; Goergen, Craig J; Chen, Howard H; Cho, Hoonsung; Sosnovik, David E; Josephson, Lee

    2012-07-09

    Easy to find: magnetic nanoparticles bearing fluorochromes (red) that intercalate with DNA (green) form microaggregates with DNA generated by the polymerase chain reaction (PCR). These aggregates can be detected at low cycle numbers by magnetic resonance (MR).

  1. Self-assembly of magnetic biofunctional nanoparticles

    SciTech Connect

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

    2005-05-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  3. Quantitative Characterization of Magnetic Mobility of Nanoparticle in Solution-Based Condition.

    PubMed

    Rodoplu, Didem; Boyaci, Ismail H; Bozkurt, Akif G; Eksi, Haslet; Zengin, Adem; Tamer, Ugur; Aydogan, Nihal; Ozcan, Sadan; Tugcu-Demiröz, Fatmanur

    2015-01-01

    Magnetic nanoparticles are considered as the ideal substrate to selectively isolate target molecules or organisms from sample solutions in a wide variety of applications including bioassays, bioimaging and environmental chemistry. The broad array of these applications in fields requires the accurate magnetic characterization of nanoparticles for a variety of solution based-conditions. Because the freshly synthesized magnetic nanoparticles demonstrated a perfect magnetization value in solid form, they exhibited a different magnetic behavior in solution. Here, we present simple quantitative method for the measurement of magnetic mobility of nanoparticles in solution-based condition. Magnetic mobility of the nanoparticles was quantified with initial mobility of the particles using UV-vis absorbance spectroscopy in water, ethanol and MES buffer. We demonstrated the efficacy of this method through a systematic characterization of four different core-shell structures magnetic nanoparticles over three different surface modifications. The solid nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD) and saturation magnetization (Ms). The surfaces of the nanoparticles were functionalized with 11-mercaptoundecanoic acid and bovine serum albumin BSA was selected as biomaterial. The effect of the surface modification and solution media on the stability of the nanoparticles was monitored by zeta potentials and hydrodynamic diameters of the nanoparticles. Results obtained from the mobility experiments indicate that the initial mobility was altered with solution media, surface functionalization, size and shape of the magnetic nanoparticle. The proposed method easily determines the interactions between the magnetic nanoparticles and their surrounding biological media, the magnetophoretic responsiveness of nanoparticles and the initial mobilities of the nanoparticles.

  4. Oxygen and light sensitive field-effect transistors based on ZnO nanoparticles attached to individual double-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Chanaewa, Alina; Juárez, Beatriz H.; Weller, Horst; Klinke, Christian

    2011-12-01

    The attachment of semiconducting nanoparticles to carbon nanotubes is one of the most challenging subjects in nanotechnology. Successful high coverage attachment and control over the charge transfer mechanism and photo-current generation open a wide field of new applications such as highly effective solar cells and fibre-enhanced polymers. In this work we study the charge transfer in individual double-walled carbon nanotubes highly covered with uniform ZnO nanoparticles. The synthetic colloidal procedure was chosen to avoid long-chained ligands at the nanoparticle-nanotube interface. The resulting composite material was used as conductive channel in a field-effect transistor device and the electrical photo-response was analysed under various conditions. By means of the transfer characteristics we could elucidate the mechanism of charge transfer from non-covalently attached semiconducting nanoparticles to carbon nanotubes. The role of positive charges remaining on the nanoparticles is discussed in terms of a gating effect.The attachment of semiconducting nanoparticles to carbon nanotubes is one of the most challenging subjects in nanotechnology. Successful high coverage attachment and control over the charge transfer mechanism and photo-current generation open a wide field of new applications such as highly effective solar cells and fibre-enhanced polymers. In this work we study the charge transfer in individual double-walled carbon nanotubes highly covered with uniform ZnO nanoparticles. The synthetic colloidal procedure was chosen to avoid long-chained ligands at the nanoparticle-nanotube interface. The resulting composite material was used as conductive channel in a field-effect transistor device and the electrical photo-response was analysed under various conditions. By means of the transfer characteristics we could elucidate the mechanism of charge transfer from non-covalently attached semiconducting nanoparticles to carbon nanotubes. The role of positive

  5. Methotrexate-conjugated magnetic nanoparticles for thermochemotherapy and magnetic resonance imaging of tumor

    NASA Astrophysics Data System (ADS)

    Gao, Fuping; Yan, Zixing; Zhou, Jing; Cai, Yuanyuan; Tang, Jintian

    2012-10-01

    There is significant interest in recent years in developing magnetic nanoparticles (MNPs) having multifunctional characteristics with complimentary roles. In this study, methotrexate (MTX) was conjugated on the iron oxide magnetic nanoparticles surface via a poly(ethyleneimine) self-assembled monolayer (MTX-MNPs). The novel platform combined cancer chemotherapy, hyperthermia and potential monitoring of the progression of disease through magnetic resonance imaging (MRI). The conjugation of MTX on the magnetite surface was confirmed by Fourier transform infrared spectroscopy and change of zeta potential. Transmission electron microscope (TEM) showed that MTX-MNPs were morphologically spherical. The average diameter of MTX-MNPs was 30.1 ± 5.2 nm determined by dynamic light scattering. Magnetic measurements revealed that the saturation magnetization of MTX-MNPs reached 68.8 emu/g and the nanoparticles were superparamagnetic. The MTX-MNPs had good heating properties in an alternating magnetic field. TEM results showed that a larger number of MTX-MNPs were internalized into the MCF-7 cellular cytoplasm compared with the MNPs. The MTX-MNPs demonstrated highly synergistic antiproliferative effects of simultaneous chemotherapy and hyperthermia in MCF-7 breast cancer cells. A significant negative contrast enhancement was observed with magnetic resonance phantom imaging for MCF-7 cells over L929cells, when both were cultured with the nanoconjugate. The MTX-MNPs with combined characteristics of thermochemotherapy and MRI could be of high clinical significance in the treatment of tumor.

  6. Magnetic poly(D,L-lactide) nanoparticles loaded with aliskiren: A promising tool for hypertension treatment

    NASA Astrophysics Data System (ADS)

    Antal, Iryna; Kubovcikova, Martina; Zavisova, Vlasta; Koneracka, Martina; Pechanova, Olga; Barta, Andrej; Cebova, Martina; Antal, Vitaliy; Diko, Pavel; Zduriencikova, Martina; Pudlak, Michal; Kopcansky, Peter

    2015-04-01

    In this study anti-hypertensive drug called aliskiren was encapsulated in magnetic poly(D,L-lactide) nanoparticles by the modified nanoprecipitation method. The effect of magnetite and drug concentrations on the size distribution and zeta potential of polymer nanoparticles was investigated. The optimized loadings were as follows: theoretical magnetite loading was 20 mg/100 mg polymer nanoparticles and aliskiren was encapsulated in magnetic poly(D,L-lactide) nanoparticles at theoretical loading 0.6 mg aliskiren/100 mg magnetic polymer nanoparticles. The physicochemical characteristics of nanoparticles were studied, with spherical shape of nanoparticles sized between 58 and 227 nm being one of the observed results. Differential scanning calorimetry and infrared spectroscopy confirmed that aliskiren was successfully identified in the magnetic poly(D,L-lactide) nanoparticles. The in vivo experiments indicated that encapsulated aliskiren decreased blood pressure of the studied male spontaneously hypertensive rat even more significantly than common administered drug.

  7. The dynamics of magnetic nanoparticles exposed to non-heating alternating magnetic field in biochemical applications: theoretical study

    NASA Astrophysics Data System (ADS)

    Golovin, Yuri I.; Gribanovsky, Sergey L.; Golovin, Dmitry Y.; Zhigachev, Alexander O.; Klyachko, Natalia L.; Majouga, Alexander G.; Sokolsky, Marina; Kabanov, Alexander V.

    2017-02-01

    In the past decade, magneto-nanomechanical approach to biochemical systems stimulation has been studied intensively. This method involves macromolecule structure local deformation via mechanical actuation of functionalized magnetic nanoparticles (f-MNPs) by non-heating low frequency (LF) alternating magnetic field (AMF). Specificity at cellular or molecular level and spatial locality in nanometer scale are its key advantages as compared to magnetic fluid hyperthermia. However, current experimental studies have weak theoretical basis. Several models of magneto-nanomechanical actuation of macromolecules and cells in non-heating uniform LF AMF are presented in the article. Single core-shell spherical, rod-like, and Janus MNPs, as well as dimers consisting of two f-MNPs with macromolecules immobilized on their surfaces are considered. AMF-induced rotational oscillations of MNPs can affect properties and functioning of macromolecules or cellular membranes attached to them via periodic deformations in nanometer scale. This could be widely used in therapy, in particular for targeted drug delivery, controlled drug release, and cancer cell killing. An aggregate composed of MNPs can affect associated macromolecules by force up to several hundreds of piconewton in the case of MNPs of tens of nanometers in diameter and LF AMF below 1 T. AMF parameters and MNP design requirements for effective in vitro and in vivo magneto-nanomechanical treatment are presented.

  8. 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

  9. Application of quercetin and its bio-inspired nanoparticles as anti-adhesive agents against Bacillus subtilis attachment to surface.

    PubMed

    Raie, Diana S; Mhatre, Eisha; Thiele, Matthias; Labena, A; El-Ghannam, Gamal; Farahat, Laila A; Youssef, Tareq; Fritzsche, Wolfgang; Kovács, Ákos T

    2017-01-01

    The aim of this study was directed to reveal the repulsive effect of coated glass slides by quercetin and its bio-inspired titanium oxide and tungsten oxide nanoparticles on physical surface attachment of Bacillus subtilis as an ab-initio step of biofilm formation. Nanoparticles were successfully synthesized using sol-gel and acid precipitation methods for titanium oxide and tungsten oxide, respectively (in the absence or presence of quercetin). The anti-adhesive impact of the coated-slides was tested through the physical attachment of B. subtilis after 24h using Confocal Laser Scanning Microscopy (CLSM). Here, quercetin was presented as a bio-route for the synthesis of tungsten mixed oxides nano-plates at room temperature. In addition, quercetin had an impact on zeta potential and adsorption capacity of both bio-inspired amorphous titanium oxide and tungsten oxide nano-plates. Interestingly, our experiments indicated a contrary effect of quercetin as an anti-adhesive agent than previously reported. However, its bio-inspired metal oxide proved their repulsive efficiency. In addition, quercetin-mediated nano-tungsten and quercetin-mediated amorphous titanium showed anti-adhesive activity against B. subtilis biofilm.

  10. Micro CT imaging assessment for spatial distribution of magnetic nanoparticles in an ex vivo thrombolysis model

    NASA Astrophysics Data System (ADS)

    Wang, Fu-Sheng; Chao, Tsi-Chian; Tu, Shu-Ju

    2012-03-01

    In recent nanotechnology development, iron-based magnetic nanoparticles (MNPs) have been used in several investigations on biomedical research for small animal experiments. Their important applications include targeted drug delivery for therapeutic purpose, contrast agent for magnetic resonance imaging, and hyperthermia treatment for tumors. These MNPs can be guided by an external magnetic field due to their physical characteristics of superparamagnetism. In a recent report, authors indicated that covalently bound recombinant tissue plasminogen activator (rtPA) to MNP (MNPrtPA) with preserved enzyme activity may be guided by a bar magnet and induce target thrombolysis in an embolic model in rats. Delivery of rtPA by binding the thrombolytic drug to MNPs will improve the possibility of the drug to be delivered under magnetic guidance and retained in a local targeted area in the circulation system. In this work, an ex vivo intravascular thrombolysis model was developed to study the impact of external magnetic field on the penetration of MNP-rtPA in the blood clot samples. The samples were then scanned by a micro CT system for quantification. Images of MNPs show strong contrast with their surrounding blood clot materials. The optimum drug loading was found when 0.5 mg/ml rtPA is conjugated with 10 mg SiO2-MNP where 98% drug was attached to the carrier with full retention of its thrombolytic activity. Effective thrombolysis with tPA bound to SiO2-MNP under magnetic guidance was demonstrated in our ex vivo model where substantial reduction in time for blood clot lysis was observed compared with control groups without magnetic field application.

  11. Understanding the physics of magnetic nanoparticles and their applications in the biomedical field

    NASA Astrophysics Data System (ADS)

    Laha, Suvra Santa

    The study of magnetic nanoparticles is of great interest because of their potential uses in magnetic-recording, medical diagnostic and therapeutic applications. Additionally, they also offer an opportunity to understand the physics underlying the complex behavior exhibited by these materials. Two of the most important relaxation phenomena occurring in magnetic nanoparticles are superparamagnetic blocking and spin-glass-like freezing. In addition to features attributed to superparamagnetism, these nanoparticles can also exhibit magnetic relaxation effects at very low temperatures (≤ 50 K). Our studies suggest that all structural defects, and not just surface spins, are responsible for the low-temperature glass-like relaxation observed in many magnetic nanoparticles. The characteristic dipolar interaction energy existing in an ensemble of magnetic nanoparticles does not apparently depend on the average spacing between the nanoparticles but is likely to be strongly influenced by the fluctuations in the nanoparticle distribution. Our findings revealed that incorporating a small percentage of boron can stabilize the spinel structure in Mn 3O4 nanoparticles. We have also demonstrated that the dipolar interactions between the magnetic cores can be tuned by introducing non-magnetic nanoparticles. In particular, we studied the magnetic properties of Gd-doped Fe3O4 nanoparticles, a potential applicant for T1--T2 dual-modal MRI contrast agent. We have explored the interactions of BiFeO3 nanoparticles on live cells and the binding of FITC-conjugated Fe3O 4 nanoparticles with artificial lipid membranes to investigate these materials as candidates in medical imaging. Taken together, these studies have advanced our understanding of the fundamental physical principles that governs magnetism in magnetic materials with a focus on developing these nanoparticles for advanced biomedical applications. The materials developed and studied expand the repertoire of tools available for

  12. Multifunctional fluorescent and magnetic nanoparticles for biomedical applications

    NASA Astrophysics Data System (ADS)

    Selvan, Subramanian T.

    2012-03-01

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

  13. Modeling and simulations of the removal of formaldehyde using silver nano-particles attached to granular activated carbon.

    PubMed

    Shin, SeungKyu; Song, JiHyeon

    2011-10-30

    A combined reaction, consisting of granular activated carbon (GAC) adsorption and catalytic oxidation, has been proposed to improve the removal efficiencies of formaldehyde, one of the major indoor air pollutants. In this study, silver nano-particles attached onto the surface of GAC (Ag-GAC) using the sputtering method were evaluated for the simultaneous catalytic oxidation and adsorption of formaldehyde. The evolution of CO(2) from the silver nano-particles indicated that formaldehyde was catalytically oxidized to its final product, with the oxidation kinetics expressed as pseudo-first order. In addition, a packed column test showed that the mass of formaldehyde removed by the Ag-GAC was 2.4 times higher than that by the virgin GAC at a gas retention time of 0.5s. However, a BET analysis showed that the available surface area and micro-pore volume of the Ag-GAC were substantially decreased due to the deposition of the silver nano-particles. To simulate the performance of the Ag-GAC, the homogeneous surface diffusion model (HSDM), developed for the prediction of the GAC column adsorption, was modified to incorporate the catalytic oxidation taking place on the Ag-GAC surface. The modified HSDM demonstrated that numerical simulations were consistent with the experimental data collected from the Ag-GAC column tests. The model predictions implied that the silver nano-particles deposited on the GAC reduced the adsorptive capacity due to decreasing the available surface for the diffusion of formaldehyde into the GAC, but the overall mass of formaldehyde removed by the Ag-GAC was increased due to catalytic oxidation as a function of the ratio of the surface coverage by the nano-particles.

  14. Preparation of magnetic polymer particles with nanoparticles of Fe(0).

    PubMed

    Buendía, S; Cabañas, G; Alvarez-Lucio, G; Montiel-Sánchez, H; Navarro-Clemente, M E; Corea, M

    2011-02-01

    Iron nanoparticles (Fe(0)), were encapsulated into polymethyl methacrylate (PMMA), by means of emulsion polymerization techniques in a semicontinuous process. The final average diameter of the composite particle was calculated until three times of average particle of iron particles and were stabilized with a non-ionic surfactant. They were then characterized by scanning electron microscopy and dynamic light scattering. Their magnetic properties were determined by parallel field vibrating-sample magnetometry method. The results indicated that the magnetic properties are a function of polymer concentration in the nanocomposite particle.

  15. 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.

  16. LSMO Nanoparticles Coated by Hyaluronic Acid for Magnetic Hyperthermia

    NASA Astrophysics Data System (ADS)

    Chen, Yuanwei; Wang, Ying; Liu, Xi; Lu, Mai; Cao, Jiangwei; Wang, Tao

    2016-12-01

    Magnetic hyperthermia with the treating temperature range of 41-46 °C is an alternative therapy for cancer treatment. In this article, lanthanum strontium manganates (La1- x Sr x MnO3, 0.25 ≤ × ≤ 0.35) magnetic nanoparticles coated by hyaluronic acid (HA) which possesses the ability of targeting tumor cells were prepared by a simple hydrothermal method combined with a high-energy ball milling technique. The crystal structure, morphology, magnetic properties of the HA-coated magnetic nanoparticles (MNPs), and their heating ability under alternating magnetic field were investigated. It was found the HA-coated La0.7Sr0.3MnO3, with particle diameter of 100 nm, Curie temperature of 45 °C at a concentration 6 mg/ml, gave the optimal induction heating results. The heating temperature saturates at 45.7 °C, and the ESAR is 5.7 × 10-3 W/g · kHz · (kA/m2) which is much higher than other reported results.

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

    PubMed

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

    2014-03-01

    The purpose of this study was to develop a specific targeting magnetic nanoparticle probe for magnetic resonance imaging and therapy in the form of local hyperthermia. Carboxymethyl dextran-coated ultrasmall superparamagnetic iron oxide nanoparticles with carboxyl groups were coupled to cyclic arginine-glycine-aspartic peptides for integrin α(v)β₃ targeting. The particle size, magnetic properties, heating effect, and stability of the arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide were measured. The arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide demonstrates excellent stability and fast magneto-temperature response. Magnetic resonance imaging signal intensity of Bcap37 cells incubated with arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide was significantly decreased compared with that incubated with plain ultrasmall superparamagnetic iron oxide. The preferential uptake of arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide by target cells was further confirmed by Prussian blue staining and confocal laser scanning microscopy.

  18. Multifunctional clickable and protein-repellent magnetic silica nanoparticles.

    PubMed

    Estupiñán, Diego; Bannwarth, Markus B; Mylon, Steven E; Landfester, Katharina; Muñoz-Espí, Rafael; Crespy, Daniel

    2016-02-07

    Silica nanoparticles are versatile materials whose physicochemical surface properties can be precisely adjusted. Because it is possible to combine several functionalities in a single carrier, silica-based materials are excellent candidates for biomedical applications. However, the functionality of the nanoparticles can get lost upon exposure to biological media due to uncontrolled biomolecule adsorption. Therefore, it is important to develop strategies that reduce non-specific protein-particle interactions without losing the introduced surface functionality. Herein, organosilane chemistry is employed to produce magnetic silica nanoparticles bearing differing amounts of amino and alkene functional groups on their surface as orthogonally addressable chemical functionalities. Simultaneously, a short-chain zwitterion is added to decrease the non-specific adsorption of biomolecules on the nanoparticles surface. The multifunctional particles display reduced protein adsorption after incubation in undiluted fetal bovine serum as well as in single protein solutions (serum albumin and lysozyme). Besides, the particles retain their capacity to selectively react with biomolecules. Thus, they can be covalently bio-functionalized with an antibody by means of orthogonal click reactions. These features make the described multifunctional silica nanoparticles a promising system for the study of surface interactions with biomolecules, targeting, and bio-sensing.

  19. Cellular effects of magnetic nanoparticles explored by atomic force microscopy.

    PubMed

    Mao, Hongli; Li, Jingchao; Dulińska-Molak, Ida; Kawazoe, Naoki; Takeda, Yoshihiko; Mamiya, Hiroaki; Chen, Guoping

    2015-09-01

    The investigation of subtle change of cells exposed to nanomaterials is extremely essential but also challenging for nanomaterial-based biological applications. In this study, atomic force microscopy (AFM) was employed to investigate the effects of iron-iron oxide core-shell magnetic nanoparticles on the mechanical properties of bovine articular chondrocytes (BACs). After being exposed to the nanoparticles even at a high nanoparticle-concentration (50 μg mL(-1)), no obvious difference was observed by using conventional methods, including the WST-1 assay and live/dead staining. However a significant difference of Young's modulus of the cells was detected by AFM even when the concentration of nanoparticles applied in the cell culture medium was low (10 μg mL(-1)). The difference of cellular Young's modulus increased with the increase of nanoparticle concentration. AFM was demonstrated to be a useful tool to identify the subtle change of cells when they were exposed to nanomaterials even at a low concentration.

  20. Synthesis and functionalisation of magnetic nanoparticles for hyperthermia applications.

    PubMed

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

    2013-12-01

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

  1. Size-dependent magnetic properties of iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Patsula, Vitalii; Moskvin, Maksym; Dutz, Silvio; Horák, Daniel

    2016-01-01

    Uniform iron oxide nanoparticles in the size range from 10 to 24 nm and polydisperse 14 nm iron oxide particles were prepared by thermal decomposition of Fe(III) carboxylates in the presence of oleic acid and co-precipitation of Fe(II) and Fe(III) chlorides by ammonium hydroxide followed by oxidation, respectively. While the first method produced hydrophobic oleic acid coated particles, the second one formed hydrophilic, but uncoated, nanoparticles. To make the iron oxide particles water dispersible and colloidally stable, their surface was modified with poly(ethylene glycol) and sucrose, respectively. Size and size distribution of the nanoparticles was determined by transmission electron microscopy, dynamic light scattering and X-ray diffraction. Surface of the PEG-functionalized and sucrose-modified iron oxide particles was characterized by Fourier transform infrared (FT-IR) and Raman spectroscopy and thermogravimetric analysis (TGA). Magnetic properties were measured by means of vibration sample magnetometry and specific absorption rate in alternating magnetic fields was determined calorimetrically. It was found, that larger ferrimagnetic particles showed higher heating performance than smaller superparamagnetic ones. In the transition range between superparamagnetism and ferrimagnetism, samples with a broader size distribution provided higher heating power than narrow size distributed particles of comparable mean size. Here presented particles showed promising properties for a possible application in magnetic hyperthermia.

  2. Stability of DNA-linked nanoparticle crystals: Effect of number of strands, core size, and rigidity of strand attachment

    NASA Astrophysics Data System (ADS)

    Padovan-Merhar, Olivia; Lara, Fernando Vargas; Starr, Francis W.

    2011-06-01

    Three-dimensional ordered lattices of nanoparticles (NPs) linked by DNA have potential applications in novel devices and materials, but most experimental attempts to form crystals result in amorphous packing. Here we use a coarse-grained computational model to address three factors that impact the stability of bcc and fcc crystals formed by DNA-linked NPs : (i) the number of attached strands to the NP surface, (ii) the size of the NP core, and (iii) the rigidity of the strand attachment. We find that allowing mobility in the attachment of DNA strands to the core NP can very slightly increase or decrease melting temperature TM. Larger changes to TM result from increasing the number of strands, which increases TM, or by increasing the core NP diameter, which decreases TM. Both results are consistent with experimental findings. Moreover, we show that the behavior of TM can be quantitatively described by the model introduced previously [F. Vargas Lara and F. W. Starr, Soft Matter, 7, 2085 (2011)], 10.1039/c0sm00989j.

  3. POLARIZATION OF MAGNETIC DIPOLE EMISSION AND SPINNING DUST EMISSION FROM MAGNETIC NANOPARTICLES

    SciTech Connect

    Hoang, Thiem; Lazarian, Alex

    2016-04-20

    Magnetic dipole emission (MDE) from interstellar magnetic nanoparticles is potentially an important Galactic foreground in the microwave frequencies, and its polarization level may pose great challenges for achieving reliable measurements of cosmic microwave background B-mode signal. To obtain realistic predictions for the polarization of MDE, we first compute the degree of alignment of big silicate grains incorporated with magnetic inclusions. We find that thermally rotating big grains with magnetic inclusions are weakly aligned and can achieve alignment saturation when the magnetic alignment rate becomes much faster than the rotational damping rate. We then compute the degree of alignment for free-flying magnetic nanoparticles, taking into account various interaction processes of grains with the ambient gas and radiation field, including neutral collisions, ion collisions, and infrared emission. We find that the rotational damping by infrared emission can significantly decrease the degree of alignment of small particles from the saturation level, whereas the excitation by ion collisions can enhance the alignment of ultrasmall particles. Using the computed degrees of alignment, we predict the polarization level of MDE from free-flying magnetic nanoparticles to be rather low. Such a polarization level is within the upper limits measured for anomalous microwave emission (AME), which indicates that MDE from free-flying iron particles may not be ruled out as a source of AME. We also quantify rotational emission from free-flying iron nanoparticles with permanent magnetic moments and find that its emissivity is about one order of magnitude lower than that from spinning polycyclic aromatic hydrocarbons.

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

    PubMed

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

    2010-12-01

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

  5. Size and thickness effect on magnetic structures of maghemite hollow magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Sayed, Fatima; Labaye, Yvan; Sayed Hassan, Rodaina; El Haj Hassan, Fouad; Yaacoub, Nader; Greneche, Jean-Marc

    2016-09-01

    The effect of surface anisotropy on the magnetic ground state of hollow maghemite nanoparticles is investigated using atomistic Monte Carlo simulation. The computer modeling is carried on hollow nanostructures as a function of size and shell thickness. It is found that the large contribution of the surface anisotropy imposes a "throttled" spin structure where the moments located at the outer surface tend to orient normal to the surface while those located at the inner surface appear to be more aligned. For increasing values of surface anisotropy in the frame of a radial model, the magnetic moments become radially oriented either inward or outward giving rise to a "hedgehog" configuration with nearly zero net magnetization. We also show the effect of the size of hollow nanoparticle on the spin behavior where the spin non-collinearity increases (for fixed value of surface anisotropy) as the diameter of the hollow nanoparticle increases due to the significant increase in surface-to-volume ratio, the thickness being constant. Moreover, the thickness of the hollow nanoparticle shell influences the spin configuration and thus the relation between surface anisotropy and the size or the thickness of the hollow nanoparticle is established.

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

    SciTech Connect

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

    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.

  7. Electronic measurements in an alternating magnetic field (AMF) for studying magnetic nanoparticle hyperthermia

    NASA Astrophysics Data System (ADS)

    Boekelheide, Z.; Hussein, Z. A.; Hartzell, S.

    Magnetic nanoparticle hyperthermia is a promising cancer treatment in which magnetic nanoparticles are injected into a tumor and then exposed to an alternating magnetic field (AMF). This process releases heat and damages tumor cells, but the exact mechanisms behind the effectiveness of this therapy are still unclear. Accurate sensors are required to monitor the temperature and, potentially, other parameters such as magnetic field or mechanical stress during clinical therapy or lab research. Often, optical rather than electronic temperature sensors are used to avoid eddy current self-heating in conducting parts in the AMF. However, eddy current heating is strongly dependent on the size and geometry of the conducting part, thus micro- and nano-scale electronics are a promising possibility for further exploration into magnetic nanoparticle hyperthermia. This presentation quantitatively discusses the eddy current self-heating of thin wires (thermocouples) and will also present a proof of concept thin film resistive thermometer and magnetic field sensor along with measurements of their eddy current self-heating. The results show that electronic measurements are feasible in an AMF with both thin wires and patterned thin film sensors under certain conditions.

  8. Generation and properties of antibacterial coatings based on electrostatic attachment of silver nanoparticles to protein-coated polypropylene fibers.

    PubMed

    Goli, Kiran K; Gera, Nimish; Liu, Xiaomeng; Rao, Balaji M; Rojas, Orlando J; Genzer, Jan

    2013-06-12

    We present a simple method for attaching silver nanoparticles to polypropylene (PP) fibers in a two-step process to impart antibacterial properties. Specifically, PP fibers are pretreated by the adsorption from an aqueous solution of heat-denatured lysozyme (LYS) followed by LYS cross-linking using glutaraldehyde and sodium borohydride. At neutral pH, the surface of the adsorbed LYS layer is enriched with numerous positive charges. Silver nanoparticles (AgNPs) capped with trisodium citrate are subsequently deposited onto the protein-coated PP. Nanoparticle binding is mediated by electrostatic interactions between the positively charged LYS layer and the negatively charged AgNPs. The density of AgNPs deposited on PP depends on the amount of protein adsorbed on the surface. UV-vis spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and scanning electron microscopy are employed to follow all preparation steps and to characterize the resulting functional surfaces. The antibacterial activity of the modified surfaces is tested against gram negative bacteria Escherichia coli (E. coli). Overall, our results show that PP surfaces coated with AgNPs exhibit excellent antibacterial activity with 100% removal efficiency.

  9. Patterned Magnetic Structures for Micro-/Nanoparticle and Cell Manipulation

    NASA Astrophysics Data System (ADS)

    Vieira, Gregory Butler

    Remote manipulation of fluid-borne magnetic particles on a surface is useful to probe, assemble, and sort microscale and nanoscale objects. By patterning magnetic structures in shapes designed to exploit local heterogeneities in thin film magnetization, we have demonstrated effective trapping mechanisms for superparamagnetic micro- and nanoparticles. The features necessary for trapping are shown to arise at domain walls or indentations in microscale and smaller magnetic wires, at the periphery of magnetized disks, and at corners of magnetized triangles. Weak (<150 Oe) in- and out-of-plane external magnetic fields modify the energy landscape of the trapped particles, allowing for the objects to be remotely maneuvered along selected routes across the surface. The mechanism is multiplexed, allowing for simultaneous manipulation of many trapped particles, and their motion is directed using a handheld user interface. Particles are able to be transported over hundreds of micrometers with velocities of upwards of 200 µm/s and average forces of up to hundreds of picoNewtons. The magnetic fields, their spatial distribution, and resulting forces are estimated by modeling magnetization of the patterned structures using micromagnetic simulation or by approximating the traps as point sources of fields. The quality of these models and their relevance for describing particle manipulation under the experimental conditions is discussed. The applicability of these techniques is demonstrated for various biological, biomolecular, and nanoscale systems. Binding of magnetic particles to cells allows for guided cell transport. Composite micelle nanostructures, only tens of nm across, are simultaneously trapped and maneuvered magnetically and tracked fluorescently, despite their small size. The implications for use of this technology in lab-on-chip devices are discussed.

  10. Direct visualization and identification of biofunctionalized nanoparticles using a magnetic atomic force microscope.

    PubMed

    Block, Stephan; Glöckl, Gunnar; Weitschies, Werner; Helm, Christiane A

    2011-09-14

    Because of its outstanding ability to image and manipulate single molecules, atomic force microscopy (AFM) established itself as a fundamental technique in nanobiotechnology. (1) We present a new modality that distinguishes single nanoparticles by the surrounding magnetic field gradient. Diamagnetic gold and superparamagnetic iron oxide nanoparticles become discernible under ambient conditions. Images of proteins, magnetolabeled with nanoparticles, demonstrate the first steps toward a magnetic analogue to fluorescence microscopy, which combines nanoscale lateral resolution of AFM with unambiguous detection of magnetic markers.

  11. Taking a hard line with biotemplating: cobalt-doped magnetite magnetic nanoparticle arrays

    NASA Astrophysics Data System (ADS)

    Bird, Scott M.; Galloway, Johanna M.; Rawlings, Andrea E.; Bramble, Jonathan P.; Staniland, Sarah S.

    2015-04-01

    Rapid advancements made in technology, and the drive towards miniaturisation, means that we require reliable, sustainable and cost effective methods of manufacturing a wide range of nanomaterials. In this bioinspired study, we take advantage of millions of years of evolution, and adapt a biomineralisation protein for surface patterning of biotemplated magnetic nanoparticles (MNPs). We employ soft-lithographic micro-contact printing to pattern a recombinant version of the biomineralisation protein Mms6 (derived from the magnetotactic bacterium Magnetospirillum magneticum AMB-1). The Mms6 attaches to gold surfaces via a cysteine residue introduced into the N-terminal region. The surface bound protein biotemplates highly uniform MNPs of magnetite onto patterned surfaces during an aqueous mineralisation reaction (with a mean diameter of 90 +/- 15 nm). The simple addition of 6% cobalt to the mineralisation reaction maintains the uniformity in grain size (with a mean diameter of 84 +/- 14 nm), and results in the production of MNPs with a much higher coercivity (increased from ~156 Oe to ~377 Oe). Biotemplating magnetic nanoparticles on patterned surfaces could form a novel, environmentally friendly route for the production of bit-patterned media, potentially the next generation of ultra-high density magnetic data storage devices. This is a simple method to fine-tune the magnetic hardness of the surface biotemplated MNPs, and could easily be adapted to biotemplate a wide range of different nanomaterials on surfaces to create a range of biologically templated devices.Rapid advancements made in technology, and the drive towards miniaturisation, means that we require reliable, sustainable and cost effective methods of manufacturing a wide range of nanomaterials. In this bioinspired study, we take advantage of millions of years of evolution, and adapt a biomineralisation protein for surface patterning of biotemplated magnetic nanoparticles (MNPs). We employ soft

  12. FEM numerical model study of heating in magnetic nanoparticles

    PubMed Central

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

    2013-01-01

    Electromagnetic heating of nanoparticles is complicated by the extremely short thermal relaxation time constants and difficulty of coupling sufficient power into the particles to achieve desired temperatures. Magnetic field heating by the hysteresis loop mechanism at frequencies between about 100 and 300 kHz has proven to be an effective mechanism in magnetic nanoparticles. Experiments at 2.45 GHz show that Fe3O4 magnetite nanoparticle dispersions in the range of 1012 to 1013 NP/mL also heat substantially at this frequency. An FEM numerical model study was undertaken to estimate the order of magnitude of volume power density, Qgen (W m−3) required to achieve significant heating in evenly dispersed and aggregated clusters of nanoparticles. The FEM models were computed using Comsol Multiphysics; consequently the models were confined to continuum formulations and did not include film nano-dimension heat transfer effects at the nanoparticle surface. As an example, the models indicate that for a single 36 nm diameter particle at an equivalent dispersion of 1013 NP/mL located within one control volume (1.0 × 10−19 m3) of a capillary vessel a power density in the neighborhood of 1017 (W m−3) is required to achieve a steady state particle temperature of 52 °C — the total power coupled to the particle is 2.44 μW. As a uniformly distributed particle cluster moves farther from the capillary the required power density decreases markedly. Finally, the tendency for particles in vivo to cluster together at separation distances much less than those of the uniform distribution further reduces the required power density. PMID:24386534

  13. FEM numerical model study of heating in magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

  14. Magnetic Properties of Ubiquitous yet Underrated Antiferromagnetic Nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  15. Synthesis and characterization of cationic lipid coated magnetic nanoparticles using multiple emulsions as microreactors

    NASA Astrophysics Data System (ADS)

    Akbaba, Hasan; Karagöz, Uğur; Selamet, Yusuf; Kantarcı, A. Gülten

    2017-03-01

    The aim of this study was to develop a novel iron oxide nanoparticle synthesis method with in-situ surface coating. For this purpose multiple emulsions were used as microreactors for the first time and magnetic iron oxide particles synthesized in the core of cationic solid lipid nanoparticles. DLS, SEM, TEM, VSM, Raman Spectrometer, XRD, and XPS techniques were performed for characterization of the magnetic nanoparticles. Obtained magnetic nanoparticles are superparamagnetic and no additional process was needed for surface adjustments. They are positively charged as a result of cationic lipid coating and has appropriate particle size (<30 nm) for drug or nucleic acid delivery. Structure analysis showed that magnetic core material is in the form of magnetite. Saturation magnetization value was measured as 15-17 emu g-1 for lipid coated magnetic nanoparticles obtained by multiple emulsion method which is reasonably sufficient for magnetic targeting.

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

    PubMed

    Wang, Guannan; Su, Xingguang

    2011-05-07

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

  17. Labeled magnetic nanoparticles assembly on polypyrrole film for biosensor applications.

    PubMed

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

    2008-05-15

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

  18. 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

  19. 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; Aktaş, 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.

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

    PubMed

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

    2012-01-01

    Both magnetic relaxometry and magnetic resonance imaging (MRI) can be used to detect and locate targeted magnetic nanoparticles, noninvasively and without ionizing radiation. Magnetic relaxometry offers advantages in terms of its specificity (only nanoparticles are detected) and the linear dependence of the relaxometry signal on the number of nanoparticles present. In this study, detection of single-core iron oxide nanoparticles by superconducting quantum interference device (SQUID)-detected magnetic relaxometry and standard 4.7 T MRI are compared. The nanoparticles were conjugated to a Her2 monoclonal antibody and targeted to Her2-expressing MCF7/Her2-18 (breast cancer cells); binding of the nanoparticles to the cells was assessed by magnetic relaxometry and iron assay. The same nanoparticle-labeled cells, serially diluted, were used to assess the detection limits and MR relaxivities. The detection limit of magnetic relaxometry was 125 000 nanoparticle-labeled cells at 3 cm from the SQUID sensors. T(2)-weighted MRI yielded a detection limit of 15 600 cells in a 150 µl volume, with r(1) = 1.1 mm(-1) s(-1) and r(2) = 166 mm(-1) s(-1). Her2-targeted nanoparticles were directly injected into xenograft MCF7/Her2-18 tumors in nude mice, and magnetic relaxometry imaging and 4.7 T MRI were performed, enabling direct comparison of the two techniques. Co-registration of relaxometry images and MRI of mice resulted in good agreement. A method for obtaining accurate quantification of microgram quantities of iron in the tumors and liver by relaxometry was also demonstrated. These results demonstrate the potential of SQUID-detected magnetic relaxometry imaging for the specific detection of breast cancer and the monitoring of magnetic nanoparticle-based therapies.

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

    PubMed Central

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

    2013-01-01

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

  2. Measurement of the nonmagnetic coating thickness of core-shell magnetic nanoparticles by controlled magnetization magnetic force microscopy

    NASA Astrophysics Data System (ADS)

    Angeloni, L.; Passeri, D.; Scaramuzzo, F. A.; Di Iorio, D.; Barteri, M.; Mantovani, D.; Rossi, M.

    2016-06-01

    Magnetic nanoparticles (MNPs) represent an interesting tool for several biomedical applications. In order to improve the dispersion stability, the biocompatibility and bio-functionality, MNPs need to be coated with non-magnetic films. The optimization of these systems requires the deep characterization not only of the magnetic core, but also of the coating features. Beside the chemical and physical properties of the coating, its thickness is another important property which can influence the size, the shape and the overall magnetic behavior of the NPs system. In this work we propose a possible method to measure the thickness of the non-magnetic coating of core-shell MNPs through the use of controlled magnetization-magnetic force microscopy (CM-MFM). A preliminary study on the applicability of the proposed method has been performed on Fe3O4 NPs coated with a Cu film.

  3. Optimization of pulse sequences in magnetic resonance lymphography of axillary lymph nodes using magnetic nanoparticles.

    PubMed

    Gharehaghaji, Nahideh; Oghabian, Mohammad Ali; Sarkar, Saeed; Amirmohseni, Saeedeh; Ghanaati, Hossein

    2009-07-01

    Magnetic resonance imaging pulse sequences have an important role in detection of lymph nodes using magnetic nanoparticles as a contrast agent. Current imaging sequences lack an optimum pulse sequence based on lymph node relaxation times after accumulation of magnetic nanoparticles. This deficiency is due to the limited information regarding the particle uptake in tissues, and their related magnetic properties used by magnetic resonance imaging. The aim of this study is to optimize the imaging pulse sequences based on in vivo measurement of relaxation times for obtaining the best contrast-enhanced images of axillary lymph nodes. In vivo studies were performed on normal rats on a 1.5 T clinical magnetic resonance imaging system. The used contrast agent was dextran coated iron oxide nanoparticles with a mean diameter of 20 nm. Relaxation time measurements were performed for enhanced (after injection) and nonenhanced axillary lymph nodes, and the surrounding tissue. Since magnetic resonance signal depends highly on tissue parameters; T1, T2, and T2*, as well as magnetic resonance acquisition parameters; repetition time and echo time, knowing the tissue characteristics is important in order to design a right magnetic resonance protocol for each application. Based on our proposed approach, the relaxivity characteristic of the lymph node after accumulation of a contrast agent and its corresponding relaxation rate is used to define optimum imaging parameters (i.e., repetition time and echo time) for maximum contrast. According to these imaging parameter values, various T1, T2, T2* and proton density weighted sequences were applied. Optimum pulse sequences were found to be T2*-weighted fast gradient echo, T1-weighted fast spoiled gradient echo and proton density-weighted fast spin echo sequences.

  4. 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

  5. Measuring and modeling the magnetic settling of superparamagnetic nanoparticle dispersions.

    PubMed

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

    2015-06-01

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

  6. Theoretical predictions for spatially-focused heating of magnetic nanoparticles guided by magnetic particle imaging field gradients

    NASA Astrophysics Data System (ADS)

    Dhavalikar, Rohan; Rinaldi, Carlos

    2016-12-01

    Magnetic nanoparticles in alternating magnetic fields (AMFs) transfer some of the field's energy to their surroundings in the form of heat, a property that has attracted significant attention for use in cancer treatment through hyperthermia and in developing magnetic drug carriers that can be actuated to release their cargo externally using magnetic fields. To date, most work in this field has focused on the use of AMFs that actuate heat release by nanoparticles over large regions, without the ability to select specific nanoparticle-loaded regions for heating while leaving other nanoparticle-loaded regions unaffected. In parallel, magnetic particle imaging (MPI) has emerged as a promising approach to image the distribution of magnetic nanoparticle tracers in vivo, with sub-millimeter spatial resolution. The underlying principle in MPI is the application of a selection magnetic field gradient, which defines a small region of low bias field, superimposed with an AMF (of lower frequency and amplitude than those normally used to actuate heating by the nanoparticles) to obtain a signal which is proportional to the concentration of particles in the region of low bias field. Here we extend previous models for estimating the energy dissipation rates of magnetic nanoparticles in uniform AMFs to provide theoretical predictions of how the selection magnetic field gradient used in MPI can be used to selectively actuate heating by magnetic nanoparticles in the low bias field region of the selection magnetic field gradient. Theoretical predictions are given for the spatial decay in energy dissipation rate under magnetic field gradients representative of those that can be achieved with current MPI technology. These results underscore the potential of combining MPI and higher amplitude/frequency actuation AMFs to achieve selective magnetic fluid hyperthermia (MFH) guided by MPI.

  7. CpG oligodeoxynucleotide-loaded PAMAM dendrimer-coated magnetic nanoparticles promote apoptosis in breast cancer cells.

    PubMed

    Taghavi Pourianazar, Negar; Gunduz, Ufuk

    2016-03-01

    One major application of nanotechnology in cancer treatment involves designing nanoparticles to deliver drugs, oligonucleotides, and genes to cancer cells. Nanoparticles should be engineered so that they could target and destroy tumor cells with minimal damage to healthy tissues. This research aims to develop an appropriate and efficient nanocarrier, having the ability of interacting with and delivering CpG-oligodeoxynucleotides (CpG-ODNs) to tumor cells. CpG-ODNs activate Toll-like receptor 9 (TLR9), which can generate a signal cascade for cell death. In our study, we utilized three-layer magnetic nanoparticles composed of a Fe3O4 magnetic core, an aminosilane (APTS) interlayer and a cationic poly(amidoamine) (PAMAM) dendrimer. This will be a novel targeted delivery system to enhance the accumulation of CpG-ODN molecules in tumor cells. The validation of CpG-ODN binding to DcMNPs was performed using agarose gel electrophoresis, UV-spectrophotometer, XPS analyses. Cytotoxicity of conjugates was assessed in MDA-MB231 and SKBR3 cancer cells based on cell viability by XTT assay and flow cytometric analysis. Our results indicated that the synthesized DcMNPs having high positive charges on their surface could attach to CpG-ODN molecules via electrostatic means. These nanoparticles with the average sizes of 40±10nm bind to CpG-ODN molecules efficiently and induce cell death in MDA-MB231 and SKBR3 tumor cells and could be considered a suitable targeted delivery system for CpG-ODN in biomedical applications. The magnetic core of these nanoparticles represents a promising option for selective drug targeting as they can be concentrated and held in position by means of an external magnetic field.

  8. Magnetization and Hysteresis of Dilute Magnetic-Oxide Nanoparticles

    NASA Astrophysics Data System (ADS)

    Skomski, Ralph; Balamurugan, B.; Sellmyer, D. J.

    2014-03-01

    Real-structure imperfections in dilute magnetic oxides tend to create small concentrations of local magnetic moments that are coupled by fairly long-range exchange interactions, mediated by p-electrons. The robustness of these interactions is caused by the strong overlap of the p orbitals, as contrasted to the much weaker interatomic exchange involving iron-series 3d electrons. The net exchange between defect moments can be positive or negative, which gives rise to spin structures with very small net moments. Similarly, the moments exhibit magnetocrystalline anisotropy, reinforced by electron hopping to and from 3d states and generally undergoing some random-anuisotropy averaging. Since the coercivity scales as 2K1/M and M is small, this creates pronounced and -- in thin films -- strongly anisotropic hysteresis loops. In finite systems with N moments, both K1 and M are reduced by a factor of order N1/2 due to random anisotropy and moment compensation, respectively, so that that typical coercivities are comparable to bulk magnets. Thermal activation readily randomizes the net moment of small oxide particles, so that the moment is easier to measure in compacted or aggregated particle ensembles. This research is supported by DOE (BES).

  9. Extracting the Shape and Size of Biomolecules Attached to a Surface as Suspended Discrete Nanoparticles.

    PubMed

    Milioni, Dimitra; Tsortos, Achilleas; Velez, Marisela; Gizeli, Electra

    2017-04-04

    The ability to derive information on the conformation of surface attached biomolecules by using simple techniques such as biosensors is currently considered of great importance in the fields of surface science and nanotechnology. Here we present a nanoshape sensitive biosensor where a simple mathematical expression is used to relate acoustic measurements to the geometrical features of a surface-attached biomolecule. The underlying scientific principle is that the acoustic ratio (ΔD/ΔF) is a measure of the hydrodynamic volume of the attached entity, mathematically expressed by its intrinsic viscosity [η]. A methodology is presented in order to produce surfaces with discretely bound biomolecules where their native conformation is maintained. Using DNA anchors we attached a spherical protein (streptavidin) and a rod-shaped DNA (47bp) to a quartz crystal microbalance (QCM) device in a suspended way and predicted correctly through acoustic measurements their conformation, i.e., shape and length. The methodology can be widely applied to draw conclusions on the conformation of any biomolecule or nanoentity upon specific binding on the surface of an acoustic wave device.

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

    DOEpatents

    Huber, Dale L.

    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.

  11. Rapid Nanoparticle Synthesis by Magnetic and Microwave Heating

    PubMed Central

    Chikan, Viktor; McLaurin, Emily J.

    2016-01-01

    Traditional hot-injection (HI) syntheses of colloidal nanoparticles (NPs) allows good separation of the nucleation and growth stages of the reaction, a key limitation in obtaining monodisperse NPs, but with limited scalability. Here, two methods are presented for obtaining NPs via rapid heating: magnetic and microwave-assisted. Both of these techniques provide improved engineering control over the separation of nucleation and growth stages of nanomaterial synthesis when the reaction is initiated from room temperature. The advantages of these techniques with preliminary data are presented in this prospective article. It is shown here that microwave assisted heating could possibly provide some selectivity in activating the nanomaterial precursor materials, while magnetic heating can produce very tiny particles in a very short time (even on the millisecond timescale), which is important for scalability. The fast magnetic heating also allows for synthesizing larger particles with improved size distribution, therefore impacting, not only the quantity, but the quality of the nanomaterials. PMID:28335212

  12. 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

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

    SciTech Connect

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

    2015-05-07

    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.

  14. 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

  15. Prediction of nanoparticle and colloid attachment on unfavorable mineral surfaces using representative discrete heterogeneity

    NASA Astrophysics Data System (ADS)

    Johnson, W. P.; Trauscht, J. S.; Pazmino, E.

    2015-12-01

    Despite several decades of research there currently exists no mechanistic theory to predict colloid attachment in porous media under environmental conditions where colloid-collector repulsion exists (unfavorable conditions for attachment). It has long been inferred that nano- to micro-scale surface heterogeneity (herein called discrete heterogeneity) drives colloid attachment under unfavorable conditions. Incorporating discrete heterogeneity into colloid-collector interaction calculations in particle trajectory simulations predicts colloid attachment under unfavorable conditions. As yet, discrete heterogeneity cannot be independently measured by spectroscopic or other approaches in ways directly relevant to colloid-surface interaction. This, combined with the fact that a given discrete heterogeneity representation will interact differently with different-sized colloids as well as different ionic strengths for a given sized colloid, suggests a strategy to back out representative discrete heterogeneity by comparison of simulations to experiments performed across a range of colloid size, solution IS, and fluid velocity. This has recently been performed for interaction of carboxylate modified polystyrene latex (CML) microsphere attachment to soda lime glass at pH 6.7 with NaCl electrolyte. However, extension to other surfaces, pH values, and electrolytes is needed. For this reason, attachment of CML (0.25, 1.1 and 2.0 µm diameters) from aqueous suspension onto a variety of unfavorable mineral surfaces (soda lime glass, muscovite and albite) was examined for multiple pH values 6.7 & 8.0), fluid velocities (1.71 × 10-3 and 5.94 ×10-3 ms-1), IS (6.0 & 20 mM), and electrolytes (NaCl, CaSO4, & multivalent mixtures). The resulting representative heterogeneities (heterodomain size and surface coverage, where heterodomain refers to nano- to micro-scale attractive domains) yielded colloid attachment predictions that were compared to predictions from existing applicable semi

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

    PubMed Central

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

    2013-01-01

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

  17. Nonaqueous magnetic nanoparticle suspensions with controlled particle size and nuclear magnetic resonance properties.

    PubMed

    Meledandri, Carla J; Stolarczyk, Jacek K; Ghosh, Swapankumar; Brougham, Dermot F

    2008-12-16

    We report the preparation of monodisperse maghemite (gamma-Fe2O3) nanoparticle suspensions in heptane, by thermal decomposition of iron(III) acetylacetonate in the presence of oleic acid and oleylamine surfactants. By varying the surfactant/Fe precursor mole ratio during synthesis, control was exerted both over the nanocrystal core size, in the range from 3 to 6 nm, and over the magnetic properties of the resulting nanoparticle dispersions. We report field-cycling 1H NMR relaxation analysis of the superparamagnetic relaxation rate enhancement of nonaqueous suspensions for the first time. This approach permits measurement of the relaxivity and provides information on the saturation magnetization and magnetic anisotropy energy of the suspended particles. The saturation magnetization was found to be in the expected range for maghemite particles of this size. The anisotropy energy was found to increase significantly with decreasing particle size, which we attribute to increased shape anisotropy. This study can be used as a guide for the synthesis of maghemite nanoparticles with selected magnetic properties for a given application.

  18. Magnetic field gradient driven self-assembly of superparamagnetic nanoparticles using programmable magnetically-recorded templates

    NASA Astrophysics Data System (ADS)

    Ye, L.; Qi, B.; Lawton, T. G.; Mefford, O. T.; Rinaldi, C.; Garzon, S.; Crawford, T. M.

    2013-03-01

    Using the enormous magnetic field gradients (100 MT/m @ z =20 nm) present near the surface of magnetic recording media, we demonstrate the fabrication of diffraction gratings with lines consisting entirely of magnetic nanoparticles assembled from a colloidal fluid onto a disk drive medium, followed by transfer to a flexible and transparent polymer thin film. These nanomanufactured gratings have line spacings programmed with commercial magnetic recording and are inherently concave with radii of curvature controlled by varying the polymer film thickness. The diffracted intensity increases non-monotonically with the length of time the colloidal fluid remains on the disk surface. In addition to comparing longitudinal and perpendicular magnetic recording, a combination of spectral diffraction efficiency measurements, magnetometry, scanning electron microscopy and inductively coupled plasma atomic emmission spectroscopy of these gratings are employed to understand colloidal nanoparticle dynamics in this extreme gradient limit. Such experiments are necessary to optimize nanoparticle assembly and obtain uniform patterned features. This low-cost and sustainable approach to nanomanufacturing could enable low-cost, high-quality diffraction gratings as well as more complex polymer nanocomposite materials assembled with single-nanometer precision.

  19. 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 (≤10⁶ 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).

  20. Magnetic Nanoparticles Cross the Blood-Brain Barrier: When Physics Rises to a Challenge

    PubMed Central

    Busquets, Maria Antònia; Espargaró, Alba; Sabaté, Raimon; Estelrich, Joan

    2015-01-01

    The blood-brain barrier is a physical and physiological barrier that protects the brain from toxic substances within the bloodstream and helps maintain brain homeostasis. It also represents the main obstacle in the treatment of many diseases of the central nervous system. Among the different approaches employed to overcome this barrier, the use of nanoparticles as a tool to enhance delivery of therapeutic molecules to the brain is particularly promising. There is special interest in the use of magnetic nanoparticles, as their physical characteristics endow them with additional potentially useful properties. Following systemic administration, a magnetic field applied externally can mediate the capacity of magnetic nanoparticles to permeate the blood-brain barrier. Meanwhile, thermal energy released by magnetic nanoparticles under the influence of radiofrequency radiation can modulate blood-brain barrier integrity, increasing its permeability. In this review, we present the strategies that use magnetic nanoparticles, specifically iron oxide nanoparticles, to enhance drug delivery to the brain.

  1. Magnetically responsive phase-change microspheres with large magnetization using ferrite nanoparticles.

    PubMed

    Du, Yufan; Wang, Yongsheng; He, Dawei; Feng, Bin; Ju, Changbin; Zhao, Huan; Fu, Ming

    2010-03-01

    Magnetically responsive phase-change microspheres were prepared and studied in this article. In the synthetic process, oleic acid was used to modify the iron oxide nanoparticles. The ferrite nanoparticles, about 10 nm in diameter, were highly dispersed due to the oleic acid on the surface of the particles, and they were encapsulated in polymethyl methacrylate (PMMA) by microemulsion polymerization with paraffin, which could be presumed from the differential scanning calorimetry (DSC) curves. According to the morphology in the scanning electron microscopy (SEM) image, the average diameter of the microspheres was about 200 nm, a large amount of nano-sized ferrite can be observed in a transmission electron microscope (TEM) image showing the structure of the microspheres. Finally, in the magnetization curve from a vibrating sample magnetometer, the saturation magnetization of microspheres was 12.2 emu/g, which was effective in the compatibility of infrared simulation and microwave absorption.

  2. Magnetic-nanoparticle-doped carbogenic nanocomposite: an effective magnetic resonance/fluorescence multimodal imaging probe.

    PubMed

    Srivastava, Sachchidanand; Awasthi, Rishi; Tripathi, Deepak; Rai, Mohit K; Agarwal, Vikas; Agrawal, Vinita; Gajbhiye, Namdeo S; Gupta, Rakesh K

    2012-04-10

    A novel and facile approach is developed to synthesize a magnetic nanoparticle (iron oxide)-doped carbogenic nanocomposite (IO-CNC) for magnetic resonance (MR)/fluorescence imaging applications. IO-CNC is synthesized by thermal decomposition of organic precursors in the presence of Fe(3) O(4) nanoparticles with an average size of 6 nm. IO-CNC shows wavelength-tunable fluorescence properties with high quantum yield. Magnetic studies confirm the superparamagnetic nature of IO-CNC at room temperature. IO-CNC shows MR contrast behavior by affecting the proton relaxation phenomena. The measured longitudinal (r(1) ) and transverse (r(2) ) relaxivity values are 4.52 and 34.75 mM(-1) s(-1) , respectively. No apparent cytotoxicity is observed and the nanocomposite shows a biocompatible nature. In vivo MR studies show both T(1) and T(2) * contrast behavior of the nanocomposite. Fluorescence imaging indicates selective uptake of IO-CNC by macrophages in spleen.

  3. Magnetic Nanoparticles with High Specific Absorption Rate at Low Alternating Magnetic Field

    PubMed Central

    Kekalo, K.; Baker, I.; Meyers, R.; Shyong, J.

    2015-01-01

    This paper describes the synthesis and properties of a new type of magnetic nanoparticle (MNP) for use in the hyperthermia treatment of tumors. These particles consist of 2–4 nm crystals of gamma-Fe2O3 gathered in 20–40 nm aggregates with a coating of carboxymethyl-dextran, producing a zetasize of 110–120 nm. Despite their very low saturation magnetization (1.5–6.5 emu/g), the specific absorption rate (SAR) of the nanoparticles is 22–200 W/g at applied alternating magnetic field (AMF) with strengths of 100–500 Oe at a frequency of 160 kHz. PMID:26884816

  4. Permanent magnetism, magnetic anisotropy, and hysteresis of thiol-capped gold nanoparticles.

    PubMed

    Crespo, P; Litrán, R; Rojas, T C; Multigner, M; de la Fuente, J M; Sánchez-López, J C; García, M A; Hernando, A; Penadés, S; Fernández, A

    2004-08-20

    We report on the experimental observation of magnetic hysteresis up to room temperature in thiol-capped Au nanoparticles with 1.4 nm size. The coercive field ranges from 860 Oe at 5 K to 250 Oe at 300 K. It is estimated that the Au atoms exhibit a magnetic moment of mu=0.036mu(B). However, Au nanoparticles with similar size but stabilized by means of a surfactant, i.e., weak interaction between protective molecules and Au surface atoms, are diamagnetic, as bulk Au samples are. The apparent ferromagnetism is consequently associated with 5d localized holes generated through Au-S bonds. These holes give rise to localized magnetic moments that are frozen in due to the combination of the high spin-orbit coupling (1.5 eV) of gold and the symmetry reduction associated with two types of bonding: Au-Au and Au-S.

  5. Effects of inter- and intra-aggregate magnetic dipolar interactions on the magnetic heating efficiency of iron oxide nanoparticles.

    PubMed

    Ovejero, J G; Cabrera, D; Carrey, J; Valdivielso, T; Salas, G; Teran, F J

    2016-04-28

    Iron oxide nanoparticles have found an increasing number of biomedical applications as sensing or trapping platforms and therapeutic and/or diagnostic agents. Most of these applications are based on their magnetic properties, which may vary depending on the nanoparticle aggregation state and/or concentration. In this work, we assess the effect of the inter- and intra-aggregate magnetic dipolar interactions on the heat dissipation power and AC hysteresis loops upon increasing the nanoparticle concentration and the hydrodynamic aggregate size. We observe different effects produced by inter- (long distance) and intra-aggregate (short distance) interactions, resulting in magnetizing and demagnetizing effects, respectively. Consequently, the heat dissipation power under alternating magnetic fields strongly reflects such different interacting phenomena. The intra-aggregate interaction results were successfully modeled by numerical simulations. A better understanding of magnetic dipolar interactions is mandatory for achieving a reliable magnetic hyperthermia response when nanoparticles are located into biological matrices.

  6. Photothermal therapy of cancer cells using magnetic carbon nanoparticles

    NASA Astrophysics Data System (ADS)

    Vardarajan, V.; Gu, L.; Kanneganti, A.; Mohanty, S. K.; Koymen, A. R.

    2011-03-01

    Photothermal therapy offers a solution for the destruction of cancer cells without significant collateral damage to otherwise healthy cells. Several attempts are underway in using carbon nanoparticles (CNPs) and nanotubes due to their excellent absorption properties in the near-infrared spectrum of biological window. However, minimizing the required number of injected nanoparticles, to ensure minimal cytotoxicity, is a major challenge. We report on the introduction of magnetic carbon nanoparticles (MCNPs) onto cancer cells, localizing them in a desired region by applying an external magnetic field and irradiating them with a near-infrared laser beam. The MCNPs were prepared in Benzene, using an electric plasma discharge, generated in the cavitation field of an ultrasonic horn. The CNPs were made ferromagnetic by use of Fe-electrodes to dope the CNPs, as confirmed by magnetometry. Transmission electron microscopy measurements showed the size distribution of these MCNPs to be in the range of 5-10 nm. For photothermal irradiation, a tunable continuous wave Ti: Sapphire laser beam was weakly focused on to the cell monolayer under an inverted fluorescence microscope. The response of different cell types to photothermal irradiation was investigated. Cell death in the presence of both MCNPs and laser beam was confirmed by morphological changes and propidium iodide fluorescence inclusion assay. The results of our study suggest that MCNP based photothermal therapy is a promising approach to remotely guide photothermal therapy.

  7. Antimicrobial applications of water-dispersible magnetic nanoparticles in biomedicine.

    PubMed

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

    2014-01-01

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

  8. Synthesis and characterization of noscapine loaded magnetic polymeric nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

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

  9. Use of a SQUID array to detect T-cells with magnetic nanoparticles in determining transplant rejection

    NASA Astrophysics Data System (ADS)

    Flynn, Edward R.; Bryant, H. C.; Bergemann, Christian; Larson, Richard S.; Lovato, Debbie; Sergatskov, Dmitri A.

    2007-04-01

    Acute rejection in organ transplant is signaled by the proliferation of T-cells that target and kill the donor cells requiring painful biopsies to detect rejection onset. An alternative non-invasive technique is proposed using a multi-channel superconducting quantum interference device (SQUID) magnetometer to detect T-cell lymphocytes in the transplanted organ labeled with magnetic nanoparticles conjugated to antibodies specifically attached to lymphocytic ligand receptors. After a magnetic field pulse, the T-cells produce a decaying magnetic signal with a characteristic time of the order of a second. The extreme sensitivity of this technique, 10 5 cells, can provide early warning of impending transplant rejection and monitor immune-suppressive chemotherapy.

  10. 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

  11. Magnetic nanoparticles to recover cellular organelles and study the time resolved nanoparticle-cell interactome throughout uptake.

    PubMed

    Bertoli, Filippo; Davies, Gemma-Louise; Monopoli, Marco P; Moloney, Micheal; Gun'ko, Yurii K; Salvati, Anna; Dawson, Kenneth A

    2014-08-27

    Nanoparticles in contact with cells and living organisms generate quite novel interactions at the interface between the nanoparticle surface and the surrounding biological environment. However, a detailed time resolved molecular level description of the evolving interactions as nanoparticles are internalized and trafficked within the cellular environment is still missing and will certainly be required for the emerging arena of nanoparticle-cell interactions to mature. In this paper promising methodologies to map out the time resolved nanoparticle-cell interactome for nanoparticle uptake are discussed. Thus silica coated magnetite nanoparticles are presented to cells and their magnetic properties used to isolate, in a time resolved manner, the organelles containing the nanoparticles. Characterization of the recovered fractions shows that different cell compartments are isolated at different times, in agreement with imaging results on nanoparticle intracellular location. Subsequently the internalized nanoparticles can be further isolated from the recovered organelles, allowing the study of the most tightly nanoparticle-bound biomolecules, analogous to the 'hard corona' that so far has mostly been characterized in extracellular environments. Preliminary data on the recovered nanoparticles suggest that significant portion of the original corona (derived from the serum in which particles are presented to the cells) is preserved as nanoparticles are trafficked through the cells.

  12. Magnetic resonance investigation of magnetic-labeled baker's yeast cells

    NASA Astrophysics Data System (ADS)

    Godoy Morais, J. P. M.; Azevedo, R. B.; Silva, L. P.; Lacava, Z. G. M.; Báo, S. N.; Silva, O.; Pelegrini, F.; Gansau, C.; Buske, N.; Safarik, I.; Safarikova, M.; Morais, P. C.

    2004-05-01

    In this study, the interaction of DMSA-coated magnetite nanoparticles (5 and 10 nm core-size) with Saccharomyces cerevisae was investigated using magnetic resonance (MR) and transmission electron microscopy (TEM). The TEM micrographs revealed magnetite nanoparticles attached externally to the cell wall. The MR data support the strong interaction among the nanoparticles supported by the cells. A remarkable shift in the resonance field was used as signature of particle attachment to the cell wall.

  13. Description and interpretation of aircraft lightning attachment electric and magnetic field measurements and video observation

    NASA Technical Reports Server (NTRS)

    Moreau, J. P.; Larigaldie, S.

    1991-01-01

    In 1988, ONERA carried out a complete airborne lightning characterization program. Among other features, the program has provided a significant amount of data from analog records of electric and magnetic field sensors to give a description of all stages of the lightning process. The initiation phase has a description of all stages of the lightning process. The initiation phase has been described in the past, so the present objective is to give a description of the other stages of the discharge, based on the observation of analog electromagnetic waveforms and of fast video (200 f/s) image processed pictures. During lightning attachment, the aircraft remains electrically connected to the lightning channel where a large variety of physical processes occur. These physical processes include recoil streamers, return strokes, and even other initiation processes of secondary discharges. Typical records of analog electromagnetic field along with relative luminosity variation of the channel, which shows that there is no extinction of the continuous current throughout the discharge process. A computation of current and potential waveforms using the transmission line formalism is presented and gives satisfactory results for the representation of two of the typical waveforms observed in the recoil streamer processes.

  14. 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

  15. 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

  16. Magnetic force microscopy of iron oxide nanoparticles and their cellular uptake.

    PubMed

    Zhang, Yu; Yang, Mo; Ozkan, Mihrimah; Ozkan, Cengiz S

    2009-01-01

    Magnetic force microscopy has the capability to detect magnetic domains from a close distance, which can provide the magnetic force gradient image of the scanned samples and also simultaneously obtain atomic force microscope (AFM) topography image as well as AFM phase image. In this work, we demonstrate the use of magnetic force microscopy together with AFM topography and phase imaging for the characterization of magnetic iron oxide nanoparticles and their cellular uptake behavior with the MCF7 carcinoma breast epithelial cells. This method can provide useful information such as the magnetic responses of nanoparticles, nanoparticle spatial localization, cell morphology, and cell surface domains at the same time for better understanding magnetic nanoparticle-cell interaction. It would help to design magnetic-related new imaging, diagnostic and therapeutic methods.

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

    PubMed Central

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

    2010-01-01

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

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

    PubMed

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

    2011-03-01

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

  19. Visible light-driven H(2) production by hydrogenases attached to dye-sensitized TiO(2) nanoparticles.

    PubMed

    Reisner, Erwin; Powell, Daniel J; Cavazza, Christine; Fontecilla-Camps, Juan C; Armstrong, Fraser A

    2009-12-30

    A study of hybrid, enzyme-modified nanoparticles able to produce H(2) using visible light as the energy source has been carried out to establish per-site performance standards for H(2) production catalysts able to operate under ambient conditions. The [NiFeSe]-hydrogenase from Desulfomicrobium baculatum (Db [NiFeSe]-H) is identified as a particularly proficient catalyst. The optimized system consisting of Db [NiFeSe]-H attached to Ru dye-sensitized TiO(2), with triethanolamine as a sacrificial electron donor, produces H(2) at a turnover frequency of approximately 50 (mol H(2)) s(-1) (mol total hydrogenase)(-1) at pH 7 and 25 degrees C, even under the typical solar irradiation of a northern European sky. The system shows high electrocatalytic stability not only under anaerobic conditions but also after prolonged exposure to air, thus making it sufficiently robust for benchtop applications.

  20. Large scale continuous synthesis of carbon-encapsulated magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Bystrzejewski, M.; Huczko, A.; Lange, H.; Baranowski, P.; Cota-Sanchez, G.; Soucy, G.; Szczytko, J.; Twardowski, A.

    2007-04-01

    Fe, Fe3C and NdC2 nanoparticles, encapsulated within carbon cages, were continuously produced during the induction thermal plasma processing of Fe14Nd2B, in the presence of methane or acetylene. The product morphology was studied by means of SEM. Further structural details were obtained from TEM, HRTEM, Raman spectroscopy and x-ray powder diffraction studies. The so-produced nanostructures have core-shell structure, with inner cavity diameters varying between 10 and 30 nm. The carbon coatings were composed of between 5 and 25 graphene layers. The carbon cages were built from sp2 carbon atoms, which protected the encapsulated nanoparticles from both oxidation and agglomeration. The plasma generated products were ferromagnetic, with maximum values of coercivity field of 600 G s, and saturation magnetization values of up to 40 emu g-1.

  1. Magnetic properties of Co Cu nanoparticles dispersed in silica matrix

    NASA Astrophysics Data System (ADS)

    de Julián Fernández, C.; Mattei, G.; Maurizio, C.; Cattaruzza, E.; Padovani, S.; Battaglin, G.; Gonella, F.; D'Acapito, F.; Mazzoldi, P.

    2005-04-01

    The magnetic properties of Co-Cu/silica nanocomposites prepared by sequential ion implantation have been investigated. The nanostructure is formed of 4 nm average size particles dispersed in silica matrix and with mainly FCC structure. The hysteresis loops at 3 K indicate that the nanoparticles have uniaxial anisotropy with values smaller than that of single Cobalt implants. The samples are characterized by a superparamagnetic behavior with blocking temperatures that depend on the Co/Cu implanted ratio, and the blocking temperature distributions are narrower than those obtained by taking into account only the particle size distribution. Results are discussed considering size effects and that the nanoparticles are formed of a Co-Cu solid solution or only of Co.

  2. Magnetic nanoparticles coated with cyclodextrins and citrate for irinotecan delivery.

    PubMed

    Monteiro, Ana P F; Caminhas, Larissa D; Ardisson, José D; Paniago, Roberto; Cortés, Maria E; Sinisterra, Rubén D

    2017-05-01

    In the present work, we study the role of different components in the formation of more stable iron oxide magnetic nanoparticles (MNPs): β-cyclodextrin (BCD), 2-hydroxypropyl-β-cyclodextrin (HP) and citrate anion. MNPs formulations were characterized by FTIR, particles size measurements, zeta potential based on dynamic light scattering principle technique, X-ray powder pattern diffraction, XPS spectroscopy, transmission electron microscopy and thermogravimetric analysis. The results showed that cyclodextrins and citrate plays a key role in order to obtain a lower size of coated MNPs and proved to be an efficient strategy to obtain a more stable colloidal dispersion, avoiding the nanoparticles oxidation, enhancing the irinotecan incorporation and release. Furthermore, citrate-coated BCD-MNPs showed the same cytotoxicity of the free IRI.

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

    PubMed

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

    2014-05-01

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

  4. Development of magnetic nanoparticle based calorimetric assay for the detection of bovine mastitis in cow milk.

    PubMed

    Chinnappan, Raja; Al Attas, Sana; Kaman, Wendy E; Bikker, Floris J; Zourob, Mohammed

    2017-04-15

    Mastitis in dairy cattle is an inflammatory reaction of the udder tissue. Mastitis increases plasmin levels, leading to an increased proteolysis of milk proteins such as casein, resulting in a significant decrease in milk quality and related dairy products. Due to its key-role in mastitis, we used plasmin proteolytic activity as a biomarker for the detection of mastitis in bovine mastitic milk. Inspired by earlier studies on protease activity using mastitic milk samples, we developed a simple colorimetric assay to distinguish mastitic milk from milk derived from healthy animals. The plasmin substrate coupled to magnetic nanoparticles form a black self-assembled monolayer on a gold sensor surface. In the presence of increased levels of plasmin, the substrate is cleaved and the peptide fragment attached to the magnetic beads, will be attracted by the magnet which is present under the sensor strips revealing the golden surface. We found the area of the golden color surface proportional to plasmin activity. The sensitivity of this method was determined to be 1 ng/ml of plasmin in vitro. Next, we tested the biosensor using mastitis positive milk of which infection is confirmed by bacterial cultures. This newly developed colorimetric biosensor has high potential in applications for the diagnosis of mastitis with potential spin offs to health, food and environmental sectors.

  5. Structural, optical, magnetic and photocatalytic properties of Co doped CuS diluted magnetic semiconductor nanoparticles

    NASA Astrophysics Data System (ADS)

    Sreelekha, N.; Subramanyam, K.; Amaranatha Reddy, D.; Murali, G.; Ramu, S.; Rahul Varma, K.; Vijayalakshmi, R. P.

    2016-08-01

    Pristine and Co doped covellite CuS nanoparticles were synthesized in aqueous solution by facile chemical co-precipitation method with Ethylene Diamine Tetra Acetic Acid (EDTA) as a stabilizing agent. EDAX measurements confirmed the presence of Co in the CuS host lattice. Hexagonal crystal structure of pure and Co doped CuS nanoparticles were authenticated by XRD patterns. TEM images indicated that sphere-shape of nanoparticles through a size ranging from 5 to 8 nm. The optical absorption edge moved to higher energies with increase in Co concentration as indicated by UV-vis spectroscopy. Magnetic measurements revealed that bare CuS sample show sign of diamagnetic character where as in Co doped nanoparticles augmentation of room temperature ferromagnetism was observed with increasing doping precursor concentrations. Photocatalytic performance of the pure and Co doped CuS nanoparticles were assessed by evaluating the degradation rate of rhodamine B solution under sun light irradiation. The 5% Co doped CuS nanoparticles provide evidence for high-quality photocatalytic activity.

  6. Magnetic nanoparticle hyperthermia enhancement of cisplatin chemotherapy cancer treatment

    PubMed Central

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

    2016-01-01

    Purpose The purpose of this study was to examine the therapeutic effect of magnetic nanoparticle hyperthermia (mNPH) combined with systemic cisplatin chemotherapy in a murine mammary adenocarcinoma model (MTGB). Materials and methods An alternating magnetic field (35.8 kA/m at 165 kHz) was used to activate 110 nm hydroxyethyl starch-coated magnetic nanoparticles (mNP) to a thermal dose of 60 min at 43 °C. Intratumoral mNP were delivered at 7.5 mg of Fe/cm3 of tumour (four equal tumour quadrants). Intraperitoneal cisplatin at 5 mg/kg body weight was administered 1 h prior to mNPH. Tumour regrowth delay time was used to assess the treatment efficacy. Results mNP hyperthermia, combined with cisplatin, was 1.7 times more effective than mNP hyperthermia alone and 1.4 times more effective than cisplatin alone (p<0.05). Conclusions Our results demonstrate that mNP hyperthermia can result in a safe and significant therapeutic enhancement for cisplatin cancer therapy. PMID:24144336

  7. Peptide-functionalized iron oxide magnetic nanoparticle for gold mining

    NASA Astrophysics Data System (ADS)

    Shen, Wei-Zheng; Cetinel, Sibel; Sharma, Kumakshi; Borujeny, Elham Rafie; Montemagno, Carlo

    2017-02-01

    Here, we present our work on preparing a novel nanomaterial composed of inorganic binding peptides and magnetic nanoparticles for inorganic mining. Two previously selected and well-characterized gold-binding peptides from cell surface display, AuBP1 and AuBP2, were exploited. This nanomaterial (AuBP-MNP) was designed to fulfill the following two significant functions: the surface conjugated gold-binding peptide will recognize and selectively bind to gold, while the magnetic nano-sized core will respond and migrate according to the applied external magnetic field. This will allow the smart nanomaterial to mine an individual material (gold) from a pool of mixture, without excessive solvent extraction, filtration, and concentration steps. The working efficiency of AuBP-MNP was determined by showing a dramatic reduction of gold nanoparticle colloid concentration, monitored by spectroscopy. The binding kinetics of AuBP-MNP onto the gold surface was determined using surface plasmon resonance (SPR) spectroscopy, which exhibits around 100 times higher binding kinetics than peptides alone. The binding capacity of AuBP-MNP was demonstrated by a bench-top mining test with gold microparticles.

  8. FEM numerical model analysis of magnetic nanoparticle tumor heating experiments.

    PubMed

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

    2014-01-01

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

  9. Monodisperse magnetite nanoparticle tracers for in vivo magnetic particle imaging

    PubMed Central

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

    2013-01-01

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