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Sample records for streptavidin-coated superparamagnetic beads

  1. Switchable cell trapping using superparamagnetic beads

    Energy Technology Data Exchange (ETDEWEB)

    Bryan, M. T.; Smith, K. H.; Real, M. E.; Bashir, M. A.; Fry, P. W.; Fischer, P.; Im, M.-Y.; Schrefl, T.; Allwood, D. A.; Haycock, J. W.

    2010-04-30

    Ni{sub 81}Fe{sub 19} microwires are investigated as the basis of a switchable template for positioning magnetically-labeled neural Schwann cells. Magnetic transmission X-ray microscopy and micromagnetic modeling show that magnetic domain walls can be created or removed in zigzagged structures by an applied magnetic field. Schwann cells containing superparamagnetic beads are trapped by the field emanating from the domain walls. The design allows Schwann cells to be organized on a surface to form a connected network and then released from the surface if required. As aligned Schwann cells can guide nerve regeneration, this technique is of value for developing glial-neuronal co-culture models in the future treatment of peripheral nerve injuries.

  2. Controlled torque on superparamagnetic beads for functional biosensors

    NARCIS (Netherlands)

    Janssen, X.J.A.; Schellekens, A.J.; van Ommering, K.; IJzendoorn, van L.J.; Prins, M.W.J.

    2009-01-01

    We demonstrate that a rotating magnetic field can be used to apply a controlled torque on superparamagnetic beads which leads to a tunable bead rotation frequency in fluid. Smooth rotation is obtained for field rotation frequencies many orders of magnitude higher than the bead rotation frequency. A

  3. Selective manipulation of superparamagnetic beads by a magnetic microchip

    KAUST Repository

    Gooneratne, Chinthaka Pasan; Yassine, Omar; Giouroudi, Ioanna; Kosel, Jü rgen

    2013-01-01

    In this paper, a magnetic microchip (MMC) is presented, to first trap and then selectively manipulate individual, superparamagnetic beads (SPBs) to another trapping site. Trapping sites are realized through soft magnetic micro disks made of Ni80Fe20

  4. Superparamagnetic beads in rotating magnetic fields: microfluidic experiments

    NARCIS (Netherlands)

    Den Toonder, J.M.J.; Bokdam, M.

    2008-01-01

    The effect of the Mason number, ratio of viscous and magnetic force, on suspended superparamagnetic micro sized beads was investigated experimentally. Microfluidic experiments were performed in a set-up that generates a rotating homogeneous magnetic field. In the presence of a magnetic field, the

  5. Magnet polepiece design for uniform magnetic force on superparamagnetic beads

    OpenAIRE

    Fallesen, Todd; Hill, David B.; Steen, Matthew; Macosko, Jed C.; Bonin, Keith; Holzwarth, George

    2010-01-01

    Here we report construction of a simple electromagnet with novel polepieces which apply a spatially uniform force to superparamagnetic beads in an optical microscope. The wedge-shaped gap was designed to keep ∂Bx∕∂y constant and B large enough to saturate the bead. We achieved fields of 300–600 mT and constant gradients of 67 T∕m over a sample space of 0.5×4 mm2 in the focal plane of the microscope and 0.05 mm along the microscope optic axis. Within this space the maximum force on a 2.8 μm di...

  6. Selective manipulation of superparamagnetic beads by a magnetic microchip

    KAUST Repository

    Gooneratne, Chinthaka Pasan

    2013-07-01

    In this paper, a magnetic microchip (MMC) is presented, to first trap and then selectively manipulate individual, superparamagnetic beads (SPBs) to another trapping site. Trapping sites are realized through soft magnetic micro disks made of Ni80Fe20, and SPB motion is controlled by current-carrying, tapered, conducting lines made of Au. The MMC was realized using standard microfabrication techniques and provides a cheap and versatile platform for microfluidic systems for cell manipulation. © 2013 IEEE.

  7. Structure and superparamagnetic behaviour of magnetite nanoparticles in cellulose beads

    Energy Technology Data Exchange (ETDEWEB)

    Correa, Jose R., E-mail: correa@fq.uh.cu [Department of General Chemistry, Faculty of Chemistry, University of Havana, Zapata and G, Havana City 10400 (Cuba); Bordallo, Eduardo [Sugar Cane-Cellulose Research Center, Cuba-9, Quivican (Cuba); Canetti, Dora [Department of Inorganic Chemistry, Faculty of Chemistry, University of Havana, Zapata and G, Havana City 10400 (Cuba); Leon, Vivian [Sugar Cane-Cellulose Research Center, Cuba-9, Quivican (Cuba); Otero-Diaz, Luis C. [Department of Inorganic Chemistry-1, Complutense University of Madrid, Madrid 28040 (Spain); Electron Microscopy Center, Complutense University of Madrid, Madrid 28040 (Spain); Negro, Carlos [Chemical Engineering Department, Complutense University of Madrid, Madrid 28040 (Spain); Gomez, Adrian [Electron Microscopy Center, Complutense University of Madrid, Madrid 28040 (Spain); Saez-Puche, Regino [Department of Inorganic Chemistry-1, Complutense University of Madrid, Madrid 28040 (Spain)

    2010-08-15

    Superparamagnetic magnetite nanoparticles were obtained starting from a mixture of iron(II) and iron(III) solutions in a preset total iron concentration from 0.04 to 0.8 mol l{sup -1} with ammonia at 25 and 70 {sup o}C. The regeneration of cellulose from viscose produces micrometrical spherical cellulose beads in which synthetic magnetite were embedded. The characterization of cellulose-magnetite beads by X-ray diffraction, Scanning and Transmission Electron Microscopy and magnetic measurement is reported. X-ray diffraction patterns indicate that the higher is the total iron concentration and temperature the higher is the crystal size of the magnetite obtained. Transmission Electron Microscopy studies of cellulose-magnetite beads revealed the distribution of magnetite nanoparticles inside pores of hundred nanometers. Magnetite as well as the cellulose-magnetite composites exhibit superparamagnetic characteristics. Field cooling and zero field cooling magnetic susceptibility measurements confirm the superparamagnetic behaviour and the blocking temperature for the magnetite with a mean size of 12.5 nm, which is 200 K.

  8. Hydrodynamic Torques and Rotations of Superparamagnetic Bead Dimers

    Science.gov (United States)

    Pease, Christopher; Etheridge, J.; Wijesinghe, H. S.; Pierce, C. J.; Prikockis, M. V.; Sooryakumar, R.

    Chains of micro-magnetic particles are often rotated with external magnetic fields for many lab-on-a-chip technologies such as transporting beads or mixing fluids. These applications benefit from faster responses of the actuated particles. In a rotating magnetic field, the magnetization of superparamagnetic beads, created from embedded magnetic nano-particles within a polymer matrix, is largely characterized by induced dipoles mip along the direction of the field. In addition there is often a weak dipole mop that orients out-of-phase with the external rotating field. On a two-bead dimer, the simplest chain of beads, mop contributes a torque Γm in addition to the torque from mip. For dimers with beads unbound to each other, mop rotates individual beads which generate an additional hydrodynamic torque on the dimer. Whereas, mop directly torques bound dimers. Our results show that Γm significantly alters the average frequency-dependent dimer rotation rate for both bound and unbound monomers and, when mop exceeds a critical value, increases the maximum dimer rotation frequency. Models that include magnetic and hydrodynamics torques provide good agreement with the experimental findings over a range of field frequencies.

  9. Effect of patterned micro-magnets on superparamagnetic beads in microchannels

    International Nuclear Information System (INIS)

    Guo, S S; Deng, Y L; Zhao, L B; Zhao, X-Z; Chan, H L W

    2008-01-01

    The trapping response of patterned micro-magnets (PMMs) was studied based on the parameters affecting superparamagnetic beads in microfluidic channels. Using replica moulding and electroplating technologies, the PMMs were fabricated on the microchannel bottom, which generated sufficient magnetic forces to bias the moments of magnetic particles in a flowing stream. A simplified physical principle was used to analyse the relative velocity of the magnetic particle in the confined space of a microchannel. The results revealed that the magnetic force contributed to the fluidic flow rate as well as to the hydrodynamic drag force. The relative velocity of magnetic particles was dependent on the frequency under an external magnetic field driven by an alternate current (ac) source. It showed that the magnetic gradient induced hysteresis characteristics of the transmission spectrum, associated with the interaction of superparamagnetic beads and magnetic field

  10. Preparation and Characterization of Super-paramagnetic Nano-beads for DNA Isolation

    Institute of Scientific and Technical Information of China (English)

    Xin XIE; Xu ZHANG; Bing Bin YU; wei Yang FE

    2004-01-01

    Unique coupling reagent, bis-(2-hydroxyethyl methacrylate) phosphate was used to prepare coated and functionalized superparamagnetic nanobeads, leading to a simple, effective method for coating the nanobeads. With this method, the thickness of the coating layer and the functional group contents on the nano-beads could be controlled by changing the quantity of the coated monomers. The nanobeads were characterized by means of transmission electron microscopy (TEM) and Fourier transformation infrared spectroscopy (FTIR). The carboxyl-modified magnetic nano-beads were employed to streamline the protocol of isolation of genomic DNA from the human whole blood.

  11. Ligand receptor dynamics at streptavidin-coated particle surfaces: A flow cytometric and spectrofluorimetric study

    Energy Technology Data Exchange (ETDEWEB)

    Buranda, T. [Univ. of New Mexico School of Medicine, Albuquerque, NM (United States)]|[Univ. of New Mexico, Albuquerque, NM (United States); Jones, G.M. [Univ. of New Mexico School of Medicine, Albuquerque, NM (United States); Nolan, J.P.; Keij, J. [Los Alamos National Labs., NM (United States); Lopez, G.P. [Univ. of New Mexico, Albuquerque, NM (United States); Sklar, L.A. [Univ. of New Mexico School of Medicine, Albuquerque, NM (United States)]|[Los Alamos National Lab., NM (United States)

    1999-04-29

    The authors have studied the binding of 5-((N-(5-(N-(6-(biotinoyl)amino)hexanoyl)amino)pentyl)thioureidyl)fluorescein (fluorescein biotin) to 6.2 {micro}m diameter, streptavidin-coated polystyrene beads using a combination of fluorimetric and flow cytometric methods. They have determined the average number of binding sites per bead, the extent of fluorescein quenching upon binding to the bead, and the association and dissociation kinetics. The authors estimate the site number to be {approx}1 million per bead. The binding of the fluorescein biotin ligand occurs in steps where the insertion of the biotin moiety into one receptor pocket is followed immediately by the capture of the fluorescein moiety by a neighboring binding pocket; fluorescence quenching is a consequence of this secondary binding. At high surface coverage, the dominant mechanism of quenching appears to be via the formation of nonfluorescent nearest-neighbor aggregates. At early times, the binding process is characterized by biphasic association and dissociation kinetics which are remarkably dependent on the initial concentration of the ligand. The rate constant for binding to the first receptor pocket of a streptavidin molecule is {approx}(1.3 {+-} 0.3) {times} 10{sup 7} 1{sup {minus}1} S{sup {minus}1}. The rate of binding of a second biotin may be reduced due to steric interference. The early time dissociative behavior is in sharp contrast to the typical stability associated with this system. The early time dissociative behavior is in sharp contrast to the typical stability associated with this system. The dissociation rate constant is as high as 0.05 s{sup {minus}1} shortly after binding, but decreases by 3 orders of magnitude after 3 h of binding. Potential sources for the time dependence of the dissociation rate constant are discussed.

  12. Manipulation of Superparamagnetic Beads on Patterned Exchange-Bias Layer Systems for Biosensing Applications.

    Science.gov (United States)

    Ehresmann, Arno; Koch, Iris; Holzinger, Dennis

    2015-11-13

    A technology platform based on a remotely controlled and stepwise transport of an array arrangement of superparamagnetic beads (SPB) for efficient molecular uptake, delivery and accumulation in the context of highly specific and sensitive analyte molecule detection for the application in lab-on-a-chip devices is presented. The near-surface transport of SPBs is realized via the dynamic transformation of the SPBs' magnetic potential energy landscape above a magnetically stripe patterned Exchange-Bias (EB) thin film layer systems due to the application of sub-mT external magnetic field pulses. In this concept, the SPB velocity is dramatically influenced by the magnitude and gradient of the magnetic field landscape (MFL) above the magnetically stripe patterned EB substrate, the SPB to substrate distance, the magnetic properties of both the SPBs and the EB layer system, respectively, as well as by the properties of the external magnetic field pulses and the surrounding fluid. The focus of this review is laid on the specific MFL design in EB layer systems via light-ion bombardment induced magnetic patterning (IBMP). A numerical approach is introduced for the theoretical description of the MFL in comparison to experimental characterization via scanning Hall probe microscopy. The SPB transport mechanism will be outlined in terms of the dynamic interplay between the EB substrate's MFL and the pulse scheme of the external magnetic field.

  13. Manipulation of Superparamagnetic Beads on Patterned Exchange-Bias Layer Systems for Biosensing Applications

    Directory of Open Access Journals (Sweden)

    Arno Ehresmann

    2015-11-01

    Full Text Available A technology platform based on a remotely controlled and stepwise transport of an array arrangement of superparamagnetic beads (SPB for efficient molecular uptake, delivery and accumulation in the context of highly specific and sensitive analyte molecule detection for the application in lab-on-a-chip devices is presented. The near-surface transport of SPBs is realized via the dynamic transformation of the SPBs’ magnetic potential energy landscape above a magnetically stripe patterned Exchange-Bias (EB thin film layer systems due to the application of sub-mT external magnetic field pulses. In this concept, the SPB velocity is dramatically influenced by the magnitude and gradient of the magnetic field landscape (MFL above the magnetically stripe patterned EB substrate, the SPB to substrate distance, the magnetic properties of both the SPBs and the EB layer system, respectively, as well as by the properties of the external magnetic field pulses and the surrounding fluid. The focus of this review is laid on the specific MFL design in EB layer systems via light-ion bombardment induced magnetic patterning (IBMP. A numerical approach is introduced for the theoretical description of the MFL in comparison to experimental characterization via scanning Hall probe microscopy. The SPB transport mechanism will be outlined in terms of the dynamic interplay between the EB substrate’s MFL and the pulse scheme of the external magnetic field.

  14. New Detection Modality for Label-Free Quantification of DNA in Biological Samples via Superparamagnetic Bead Aggregation

    Science.gov (United States)

    Leslie, Daniel C.; Li, Jingyi; Strachan, Briony C.; Begley, Matthew R.; Finkler, David; Bazydlo, Lindsay L.; Barker, N. Scott; Haverstick, Doris; Utz, Marcel; Landers, James P.

    2012-01-01

    Combining DNA and superparamagnetic beads in a rotating magnetic field produces multiparticle aggregates that are visually striking, and enables label-free optical detection and quantification of DNA at levels in the picogram per microliter range. DNA in biological samples can be quantified directly by simple analysis of optical images of microfluidic wells placed on a magnetic stirrer without DNA purification. Aggregation results from DNA/bead interactions driven either by the presence of a chaotrope (a nonspecific trigger for aggregation) or by hybridization with oligonucleotides on functionalized beads (sequence-specific). This paper demonstrates quantification of DNA with sensitivity comparable to that of the best currently available fluorometric assays. The robustness and sensitivity of the method enable a wide range of applications, illustrated here by counting eukaryotic cells. Using widely available and inexpensive benchtop hardware, the approach provides a highly accessible low-tech microscale alternative to more expensive DNA detection and cell counting techniques. PMID:22423674

  15. Lab-on-a-Chip Magneto-Immunoassays: How to Ensure Contact between Superparamagnetic Beads and the Sensor Surface

    Directory of Open Access Journals (Sweden)

    Andreas Hütten

    2013-09-01

    Full Text Available Lab-on-a-chip immuno assays utilizing superparamagnetic beads as labels suffer from the fact that the majority of beads pass the sensing area without contacting the sensor surface. Different solutions, employing magnetic forces, ultrasonic standing waves, or hydrodynamic effects have been found over the past decades. The first category uses magnetic forces, created by on-chip conducting lines to attract beads towards the sensor surface. Modifications of the magnetic landscape allow for additional transport and separation of different bead species. The hydrodynamic approach uses changes in the channel geometry to enhance the capture volume. In acoustofluidics, ultrasonic standing waves force µm-sized particles onto a surface through radiation forces. As these approaches have their disadvantages, a new sensor concept that circumvents these problems is suggested. This concept is based on the granular giant magnetoresistance (GMR effect that can be found in gels containing magnetic nanoparticles. The proposed design could be realized in the shape of paper-based test strips printed with gel-based GMR sensors.

  16. Rapid, highly sensitive detection of herpes simplex virus-1 using multiple antigenic peptide-coated superparamagnetic beads.

    Science.gov (United States)

    Ran, Ying-Fen; Fields, Conor; Muzard, Julien; Liauchuk, Viktoryia; Carr, Michael; Hall, William; Lee, Gil U

    2014-12-07

    A sensitive, rapid, and label free magnetic bead aggregation (MBA) assay has been developed that employs superparamagnetic (SPM) beads to capture, purify, and detect model proteins and the herpes simplex virus (HSV). The MBA assay is based on monitoring the aggregation state of a population of SPM beads using light scattering of individual aggregates. A biotin-streptavidin MBA assay had a femtomolar (fM) level sensitivity for analysis times less than 10 minutes, but the response of the assay becomes nonlinear at high analyte concentrations. A MBA assay for the detection of HSV-1 based on a novel peptide probe resulted in the selective detection of the virus at concentrations as low as 200 viral particles (vp) per mL in less than 30 min. We define the parameters that determine the sensitivity and response of the MBA assay, and the mechanism of enhanced sensitivity of the assay for HSV. The speed, relatively low cost, and ease of application of the MBA assay promise to make it useful for the identification of viral load in resource-limited and point-of-care settings where molecular diagnostics cannot be easily implemented.

  17. Superparamagnetic poly(methyl methacrylate) beads for nattokinase purification from fermentation broth.

    Science.gov (United States)

    Yang, Chengli; Xing, Jianmin; Guan, Yueping; Liu, Huizhou

    2006-09-01

    An effective method for purification of nattokinase from fermentation broth using magnetic poly(methyl methacrylate) (PMMA) beads immobilized with p-aminobenzamidine was proposed in this study. Firstly, magnetic PMMA beads with a narrow size distribution were prepared by spraying suspension polymerization. Then, they were highly functionalized via transesterification reaction with polyethylene glycol. The surface hydroxyl-modified magnetic beads obtained were further modified with chloroethylamine to transfer the surface amino-modified magnetic functional beads. The morphology and surface functionality of the magnetic beads were examined by scanning electron microscopy and Fourier transform infrared. An affinity ligand, p-aminobenzamidine was covalently immobilized to the amino-modified magnetic beads by the glutaraldehyde method for nattokinase purification directly from the fermentation broth. The purification factor and the recovery of the enzyme activity were found to be 8.7 and 85%, respectively. The purification of nattokinase from fermentation broth by magnetic beads only took 40 min, which shows a very fast purification of nattokinase compared to traditional purification methods.

  18. Observation of the dynamics of magnetically induced chains of sub-micron superparamagnetic beads in aqueous solutions by laser light scattering

    International Nuclear Information System (INIS)

    Tanizawa, Y; Tashiro, T; Sandhu, A; Ko, P J

    2013-01-01

    Optical monitoring the behaviour of magnetically induced self-assembled chains of superparamagnetic beads (SPBs) are of interest for biomedical applications such as biosensors. However, it is difficult to directly monitor magnetically induced self-assembly of sub-micron nano-beads with conventional optical microscopes. Here, we describe the optical observation of the dynamics of magnetically induced self-assembled rotating chains of 130 nm SPBs in aqueous solutions by laser light scattering. Magnetic fields of ∼1 kOe were applied to control the self-assembly chains of SPBs and their behaviour analyzed by monitoring the intensity of laser light scattered from the chain structures. We compared the light scattering from chains that were formed only by the application of external fields with chains formed by beads functionalized by EDC, where chemical reactions lead to the bonding of individual beads to form chains. The EDC experiments are a precursor to experiments on molecular recognition applications for biomedical diagnostics.

  19. Beads.

    Science.gov (United States)

    Weewish Tree, 1979

    1979-01-01

    Beads served both as ornaments and as a medium of exchange, and the Indians manufactured them from such natural sources as bones, stones, beans, nuts, animal teeth, and polished antlers. Even after the introduction of European glass beads, the Indians continued to make their favorite beads from the natural sources. (DS)

  20. In vivo biotinylation of recombinant beta-glucosidase enables simultaneous purification and immobilization on streptavidin coated magnetic particles

    DEFF Research Database (Denmark)

    Alftrén, Johan; Ottow, Kim Ekelund; Hobley, Timothy John

    2013-01-01

    Beta-glucosidase from Bacillus licheniformis was in vivo biotinylated in Escherichia coli and subsequently immobilized directly from cell lysate on streptavidin coated magnetic particles. In vivo biotinylation was mediated by fusing the Biotin Acceptor Peptide to the C-terminal of beta......-glucosidase and co-expressing the BirA biotin ligase. The approach enabled simultaneous purification and immobilization of the enzyme from crude cell lysate on magnetic particles because of the high affinity and strong interaction between biotin and streptavidin. After immobilization of the biotinylated beta...

  1. Influence of Immobilized Biomolecules on Magnetic Bead Plug Formation and Retention in Capillary Electrophoresis

    Science.gov (United States)

    Henken, Rachel L.; Chantiwas, Rattikan; Gilman, S. Douglass

    2012-01-01

    Significant changes in the formation and retention of magnetic bead plugs in a capillary during electrophoresis were studied, and it was demonstrated that these effects were due to the type of biological molecule immobilized on the surface of these beads. Three biological molecules, an antibody, an oligonucleotide and alkaline phosphatase, were attached to otherwise identical streptavidin-coated magnetic beads through biotin-avidin binding in order to isolate differences in bead immobilization in a magnetic field resulting from the type of biological molecule immobilized on the bead surface. Alkaline phosphatase also was attached to the magnetic beads using epoxy groups on the bead surfaces (instead of avidin-biotin binding) to study the impact of immobilization chemistry. The formation and retention of magnetic bead plugs were studied quantitatively using light scattering detection of magnetic particles eluting from the bead plugs and qualitatively using microscopy. Both the type of biomolecule immobilized on the magnetic bead surface and the chemistry used to link the biomolecule to the magnetic bead impacted the formation and retention of the bead plugs. PMID:22437880

  2. Electrical control of superparamagnetism

    Science.gov (United States)

    Yamada, Kihiro T.; Koyama, Tomohiro; Kakizakai, Haruka; Miwa, Kazumoto; Ando, Fuyuki; Ishibashi, Mio; Kim, Kab-Jin; Moriyama, Takahiro; Ono, Shimpei; Chiba, Daichi; Ono, Teruo

    2017-01-01

    The electric field control of superparamagnetism is realized using a Cu/Ni system, in which the deposited Ni shows superparamagnetic behavior above the blocking temperature. An electric double-layer capacitor (EDLC) with the Cu/Ni electrode and a nonmagnetic counter electrode is fabricated to examine the electric field effect on magnetism in the magnetic electrode. By changing the voltage applied to the EDLC, the blocking temperature of the system is clearly modulated.

  3. Enzyme-linked electrochemical DNA ligation assay using magnetic beads.

    Science.gov (United States)

    Stejskalová, Eva; Horáková, Petra; Vacek, Jan; Bowater, Richard P; Fojta, Miroslav

    2014-07-01

    DNA ligases are essential enzymes in all cells and have been proposed as targets for novel antibiotics. Efficient DNA ligase activity assays are thus required for applications in biomedical research. Here we present an enzyme-linked electrochemical assay based on two terminally tagged probes forming a nicked junction upon hybridization with a template DNA. Nicked DNA bearing a 5' biotin tag is immobilized on the surface of streptavidin-coated magnetic beads, and ligated product is detected via a 3' digoxigenin tag recognized by monoclonal antibody-alkaline phosphatase conjugate. Enzymatic conversion of napht-1-yl phosphate to napht-1-ol enables sensitive detection of the voltammetric signal on a pyrolytic graphite electrode. The technique was tested under optimal conditions and various situations limiting or precluding the ligation reaction (such as DNA substrates lacking 5'-phosphate or containing a base mismatch at the nick junction, or application of incompatible cofactor), and utilized for the analysis of the nick-joining activity of a range of recombinant Escherichia coli DNA ligase constructs. The novel technique provides a fast, versatile, specific, and sensitive electrochemical assay of DNA ligase activity.

  4. On-chip measurement of the Brownian relaxation frequency of magnetic beads using magnetic tunneling junctions

    DEFF Research Database (Denmark)

    Donolato, M.; Sogne, E.; Dalslet, Bjarke Thomas

    2011-01-01

    We demonstrate the detection of the Brownian relaxation frequency of 250 nm diameter magnetic beads using a lab-on-chip platform based on current lines for exciting the beads with alternating magnetic fields and highly sensitive magnetic tunnel junction (MTJ) sensors with a superparamagnetic free...

  5. Comparison between simulation and experimentally observed interactions between two magnetic beads in a fluidic system

    Energy Technology Data Exchange (ETDEWEB)

    Oduwole, Olayinka, E-mail: olayinka.oduwole@eng.ox.ac.uk; Grob, David Tim, E-mail: tim.grob@eng.ox.ac.uk; Sheard, Steve, E-mail: steve.sheard@eng.ox.ac.uk

    2016-06-01

    Continuous flow separation of magnetic particles within a microfluidic device could lead to improved performance of magnetic bead-based assays but the undesirable formation of bead clusters reduces its efficiency; this efficiency refers to the ability to separate bound magnetic beads from a mixture of particles. Such agglomerates are formed due to magnetic binding forces while hydrodynamic interactions strongly influence the particles' movement. This paper presents a model for interactions between a pair of equal sized super-paramagnetic beads suspended in water within a uniform magnetic field. To the best of our knowledge, we present for the first time a comparison between simulated trajectories and the beads' movement captured on video; the beads were suspended in a stationary fluid placed within a uniform magnetic field. In conclusion, the model is a good approximation for beads interacting with their nearest neighbours and is able to predict the trajectory pattern of these particles in a magnetic bead-based assay. Predicting the magnetically induced interaction of nearby beads will help in determining the density of beads in an assay and in avoiding agglomeration over a fixed time duration. - Highlights: • We modelled the interactions between a pair of super-paramagnetic beads suspended in water within a uniform magnetic field. • We tracked the movement of the bead pair and captured it on video. • We compared the numerical results with the video data and achieved a good agreement. • We predicted the agglomeration time as a function of the separation distance.

  6. Superparamagnetic bead interactions with functionalized surfaces characterized by an immunomicroarray

    DEFF Research Database (Denmark)

    Skottrup, Peter Durand; Hansen, Mikkel Fougt; Moresco, Jacob Lange

    2010-01-01

    optimized Polyethylene glycol-based surfaces with different end groups on the anchor molecule, 2,4,6-trichloro-1,3,5-triazine (TsT), were synthesized and compared with the standard (3-aminopropyl)triethoxysilane (APTS)/glutaraldehyde chemistry APTS/glutaraldehyde, directly linked TsT and bare H2O2-activated...

  7. Flow-orthogonal bead oscillation in a microfluidic chip with a magnetic anisotropic flux-guide array

    DEFF Research Database (Denmark)

    Van Pelt, Stijn; Derks, Roy; Matteucci, Marco

    2011-01-01

    A new concept for the manipulation of superparamagnetic beads inside a microfluidic chip is presented in this paper. The concept allows for bead actuation orthogonal to the flow direction inside a microchannel. Basic manipulation functionalities were studied by means of finite element simulations...

  8. Magnetic Bead Based Immunoassay for Autonomous Detection of Toxins

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Y; Hara, C A; Knize, M G; Hwang, M H; Venkatesteswaran, K S; Wheeler, E K; Bell, P M; Renzi, R F; Fruetel, J A; Bailey, C G

    2008-05-01

    As a step towards toward the development of a rapid, reliable analyzer for bioagents in the environment, we are developing an automated system for the simultaneous detection of a group of select agents and toxins. To detect toxins, we modified and automated an antibody-based approach previously developed for manual medical diagnostics that uses fluorescent eTag{trademark} reporter molecules and is suitable for highly multiplexed assays. Detection is based on two antibodies binding simultaneously to a single antigen, one of which is labeled with biotin while the other is conjugated to a fluorescent eTag{trademark} through a cleavable linkage. Aqueous samples are incubated with the mixture of antibodies along with streptavidin-coated magnetic beads coupled to a photo-activatable porphyrin complex. In the presence of antigen, a molecular complex is formed where the cleavable linkage is held in proximity to the photoactivable group. Upon excitation at 680 nm, free radicals are generated, which diffuse and cleave the linkage, releasing the eTags{trademark}. Released eTags{trademark} are analyzed using capillary gel electrophoresis with laser-induced fluorescence detection. Limits of detection for ovalbumin and botulinum toxoid individually were 4 ng/mL (or 80 pg) and 16 ng/mL (or 320 pg), respectively, using the manual assay. In addition, we demonstrated the use of pairs of antibodies from different sources in a single assay to decrease the rate of false positives. Automation of the assay was demonstrated on a flow-through format with higher LODs of 125 ng/mL (or 2.5 ng) each of a mixture of ovalbumin and botulinum toxoid. This versatile assay can be easily modified with the appropriate antibodies to detect a wide range of toxins and other proteins.

  9. Superparamagnetic microbead transport induced by a magnetic field on large-area magnetic antidot arrays

    Science.gov (United States)

    Ouk, Minae; Beach, Geoffrey S. D.

    2017-12-01

    A method is presented for directed transport of superparamagnetic microbeads (SPBs) on magnetic antidot patterned substrates by applying a rotating elliptical magnetic field. We find a critical frequency for transport, beyond which the bead dynamics transitions from stepwise locomotion to local oscillation. We also find that the out-of-plane (HOOP) and in-plane (HIP) field magnitudes play crucial roles in triggering bead motion. Namely, we find threshold values in HOOP and HIP that depend on bead size, which can be used to independently and remotely address specific bead populations in a multi-bead mixture. These behaviors are explained in terms of the dynamic potential energy lansdscapes computed from micromagnetic simulations of the substrate magnetization configuration. Finally, we show that large-area magnetic patterns suitable for particle transport and sorting can be fabricated through a self-assembly lithography technique, which provides a simple, cost-effective means to integrate magnetic actuation into microfluidic systems.

  10. Binding assays with streptavidin-functionalized superparamagnetic nanoparticles and biotinylated analytes using fluxgate magnetorelaxometry

    International Nuclear Information System (INIS)

    Heim, Erik; Ludwig, Frank; Schilling, Meinhard

    2009-01-01

    Binding assays based on the magnetorelaxation of superparamagnetic nanoparticles as markers are presented utilizing a differential fluxgate system. As ligand and receptor, streptavidin and biotin, respectively, are used. Superparamagnetic nanoparticles are functionalized with streptavidin and bound to two types of biotinylated analytes: agarose beads and bovine serum (BSA) proteins. The size difference of the two analytes causes a different progress of the reaction. As a consequence, the analysis of the relaxation signal is carried out dissimilarly for the two analytes. In addition, we studied the reaction kinetics of the two kinds of analytes with the fluxgate system.

  11. Aptamer-Modified Magnetic Beads in Biosensing

    Science.gov (United States)

    Scheper, Thomas; Walter, Johanna-Gabriela

    2018-01-01

    Magnetic beads (MBs) are versatile tools for the purification, detection, and quantitative analysis of analytes from complex matrices. The superparamagnetic property of magnetic beads qualifies them for various analytical applications. To provide specificity, MBs can be decorated with ligands like aptamers, antibodies and peptides. In this context, aptamers are emerging as particular promising ligands due to a number of advantages. Most importantly, the chemical synthesis of aptamers enables straightforward and controlled chemical modification with linker molecules and dyes. Moreover, aptamers facilitate novel sensing strategies based on their oligonucleotide nature that cannot be realized with conventional peptide-based ligands. Due to these benefits, the combination of aptamers and MBs was already used in various analytical applications which are summarized in this article. PMID:29601533

  12. An integrated open-cavity system for magnetic bead manipulation.

    Science.gov (United States)

    Abu-Nimeh, F T; Salem, F M

    2013-02-01

    Superparamagnetic beads are increasingly used in biomedical assays to manipulate, transport, and maneuver biomaterials. We present a low-cost integrated system designed in bulk CMOS to manipulate and separate biomedical magnetic beads. The system consists of 8 × 8 coil-arrays suitable for single bead manipulation, or collaborative multi-bead manipulation, using pseudo-parallel executions. We demonstrate the flexibility of the design in terms of different coil sizes, DC current levels, and layout techniques. In one array module example, the size of a single coil is 30 μm × 30 μm and the full array occupies an area of 248 μm × 248 μm in 0.5 μm CMOS technology. The programmable DC current source supports 8 discrete levels up to 1.5 mA. The total power consumption of the entire module is 9 mW when running at full power.

  13. Effect of algal density in bead, bead size and bead concentrations ...

    African Journals Online (AJOL)

    Effect of algal density in bead, bead size and bead concentrations on wastewater nutrient removal. ... African Journal of Biotechnology ... The bioreactor containing algal beads (4 mm diameter) with 1.5 x 106 cells bead-1 (cell stocking) at concentration of 10.66 beads ml-1 wastewater (1:3 bead: wastewater, v/v) achieved ...

  14. Magnetic bead manipulation in a sub-microliter fluid volume applicable for biosensing

    NARCIS (Netherlands)

    Derks, R.J.S.; Wimberger-Friedl, R.; Prins, M.W.J.; Dietzel, A.H.

    2007-01-01

    Magnetic actuation principles using superparamagnetic beads suspended in a fluid are studied in this paper. An exptl. setup contg. a submicroliter fluid vol. surrounded by four miniaturized electromagnets was designed and fabricated. On the basis of optical velocity measurements, the induced

  15. A String of Beads

    Science.gov (United States)

    Mead, Kelly C.

    2006-01-01

    In this article, the author relates how she designed a math activity she called Beads to use in conjunction with their school's 100th day celebration. Beads has provided her kindergarten class with many opportunities to practice a variety of math skills - counting, patterning, sorting, comparing, making sets, predicting, identifying numerals,…

  16. Degeneration of biogenic superparamagnetic magnetite.

    Science.gov (United States)

    Li, Y-L; Pfiffner, S M; Dyar, M D; Vali, H; Konhauser, K; Cole, D R; Rondinone, A J; Phelps, T J

    2009-01-01

    Magnetite crystals precipitated as a consequence of Fe(III) reduction by Shewanella algae BrY after 265 h incubation and 5-year anaerobic storage were investigated with transmission electron microscopy, Mössbauer spectroscopy and X-ray diffraction. The magnetite crystals were typically superparamagnetic with an approximate size of 13 nm. The lattice constants of the 265 h and 5-year crystals are 8.4164A and 8.3774A, respectively. The Mössbauer spectra indicated that the 265 h magnetite had excess Fe(II) in its crystal-chemistry (Fe(3+) (1.990)Fe(2+) (1.015)O(4)) but the 5-year magnetite was Fe(II)-deficient in stoichiometry (Fe(3+) (2.388)Fe(2+) (0.419)O(4)). Such crystal-chemical changes may be indicative of the degeneration of superparamagnetic magnetite through the aqueous oxidization of Fe(II) anaerobically, and the concomitant oxidation of the organic phases (fatty acid methyl esters) that were present during the initial formation of the magnetite. The observation of a corona structure on the aged magnetite corroborates the anaerobic oxidation of Fe(II) on the outer layers of magnetite crystals. These results suggest that there may be a possible link between the enzymatic activity of the bacteria and the stability of Fe(II)-excess magnetite, which may help explain why stable nano-magnetite grains are seldom preserved in natural environments.

  17. Degeneration of Biogenic Superparamagnetic Magnetite

    Energy Technology Data Exchange (ETDEWEB)

    Li, Dr. Yi-Liang [University of Tennessee, Knoxville (UTK); Pfiffner, Susan M. [University of Tennessee, Knoxville (UTK); Dyar, Dr. M Darby [Mount Holyoke College; Vali, Dr. Hojatolah [McGill University, Montreal, Quebec; Konhauser, Dr, Kurt [University of Alberta; Cole, David R [ORNL; Rondinone, Adam Justin [ORNL; Phelps, Tommy Joe [ORNL

    2009-01-01

    ABSTRACT. Magnetite crystals precipitated as a consequence of Fe(III) reduction by Shewanella algae BrY after 265 hours incubation and 5-year storage were investigated with transmission electron microscopy, M ssbauer spectroscopy and X-ray diffraction. The magnetite crystals were typically superparamagnetic with an approximate size of 13 nm. The lattice constants of the 265 hour and 5-year crystals are 8.4164 and 8.3774 , respectively. The M ssbauer spectra indicated that the 265 hour magnetite had excess Fe(II) in its crystal-chemistry (Fe3+1.9901Fe2+ 1.0149O4) but the 5-year magnetite was Fe(II)-deficient in stoichiometry (Fe3+2.3875Fe2+0.4188O4). Such crystal-hemical changes may be indicative of the degeneration of superparamagnetic magnetite through the aqueous oxidization of Fe(II) anaerobically, and the concomitant oxidation of the organic phases(fatty acid methyl esters) that were present during the initial formation of the magnetite. The observation of a corona structure on the aged magnetite corroborates the oxidation of Fe(II) on the outer layers of magnetite crystals. These results suggest that there may be a possible link between the enzymatic activity of the bacteria and the stability of Fe(II)-excess magnetite, which may help explain why stable nano-magnetite grains are seldom preserved in natural environments.

  18. Characterization of PEI-coated superparamagnetic iron oxide nanoparticles for transfection: Size distribution, colloidal properties and DNA interaction

    Energy Technology Data Exchange (ETDEWEB)

    Steitz, Benedikt [Laboratory of Powder Technology, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland); Hofmann, Heinrich [Laboratory of Powder Technology, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland); Kamau, Sarah W. [Institute of Veterinary Biochemistry and Molecular Biology, University of Zuerich, Zurich (Switzerland); Hassa, Paul O. [Institute of Veterinary Biochemistry and Molecular Biology, University of Zuerich, Zurich (Switzerland); Hottiger, Michael O. [Institute of Veterinary Biochemistry and Molecular Biology, University of Zuerich, Zurich (Switzerland); Rechenberg, Brigitte von [Musculoskeletal Research Unit, Equine Hospital, Vetsuisse Faculty Zurich, University of Zurich, Winterthurerstr. 260, 8057 Zurich (Switzerland); Hofmann-Amtenbrink, Magarethe [MatSearch, Chemin Jean Pavillard 14, 1009 Pully (Switzerland); Petri-Fink, Alke [Laboratory of Powder Technology, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland)]. E-mail: alke.fink@epfl.ch

    2007-04-15

    Superparamagnetic iron oxide nanoparticles (SPIONs) were coated with polyethylenimine. Here, we briefly describe the synthesis as well as DNA:PEI:SPION complexes and the characterization of the compounds according to their particle size, {zeta}-potential, morphology, DNA complexing ability, magnetic sedimentation, and colloidal stability. PEI coating of SPIONs led to colloidally stable beads even in high salt concentrations over a wide pH range. DNA plasmids and PCR products encoding for green fluorescent protein were associated with the described beads. The complexes were added to cells and exposed to permanent and pulsating magnetic fields. Presence of these magnetic fields significantly increased the transfection efficiency.

  19. Characterization of PEI-coated superparamagnetic iron oxide nanoparticles for transfection: Size distribution, colloidal properties and DNA interaction

    International Nuclear Information System (INIS)

    Steitz, Benedikt; Hofmann, Heinrich; Kamau, Sarah W.; Hassa, Paul O.; Hottiger, Michael O.; Rechenberg, Brigitte von; Hofmann-Amtenbrink, Magarethe; Petri-Fink, Alke

    2007-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) were coated with polyethylenimine. Here, we briefly describe the synthesis as well as DNA:PEI:SPION complexes and the characterization of the compounds according to their particle size, ζ-potential, morphology, DNA complexing ability, magnetic sedimentation, and colloidal stability. PEI coating of SPIONs led to colloidally stable beads even in high salt concentrations over a wide pH range. DNA plasmids and PCR products encoding for green fluorescent protein were associated with the described beads. The complexes were added to cells and exposed to permanent and pulsating magnetic fields. Presence of these magnetic fields significantly increased the transfection efficiency

  20. In-bead screening

    DEFF Research Database (Denmark)

    2013-01-01

    The present invention relates to screening of one-bead-one-compound (OBOC) combinatorial libraries which is useful for the discovery of compounds displaying molecular interactions with a biological or a physicochemical system, such as substrates and inhibitors of enzymes and the like. The invention...... provides a method for screening a library of compounds for their interaction with a physico- chemical or biological system and a corresponding kit for performing the method of screening a one-bead-one-compound library of compounds....

  1. Effect of algal density in bead, bead size and bead concentrations ...

    African Journals Online (AJOL)

    Laboratory experiments were performed to study nitrogen and phosphorus uptake by the unicellular green microalga Chlorella vulgaris immobilized in calcium alginate beads. Different cell stockings in beads, different bead sizes and different algal bead concentrations in wastewaters were tested. Significant higher nutrients ...

  2. A multi-purpose ultrasonic streaming mixer for integrated magnetic bead ELISAs

    International Nuclear Information System (INIS)

    Brandhoff, Lukas; Lang, Walter; Vellekoop, Michael J; Zirath, Helene; Peham, Johannes; Wiesinger-Mayr, Herbert; Salas, Mariugenia; Haller, Anna; Spittler, Andreas; Schnetz, Guntram

    2015-01-01

    We present an ultrasonic streaming mixer for disposable and on-chip magnetic bead ELISAs. The ultrasonic transducer is placed at system-level to keep cost per chip as low as possible, and is coupled to the chip by means of a solid ultrasonic horn. The system provides mixing of liquids, as well as dispersion of the superparamagnetic beads in the ELISA. Additionally it can be used clean the chamber surface from nonspecifically bound proteins during the washing steps in the ELISA protocol. Using our system the time for the ELISA protocol has been greatly reduced down to 30 min. (paper)

  3. Sangadzhi Kononov, Buddhist Prayer Beads

    OpenAIRE

    Churyumov, Anton; Kovaeva, Bair

    2016-01-01

    Prayer beads have special dividers that divide the beads into 7, 21 and 33. Apart from using in prayers, the Kalmyks also keep beads as amulets that are believed to have strong energy. After prayers, old people often bless their children and grandchildren with their beads. Such beads are also kept in families from one generation to the next. Sangadzhi believes that prayer beads store inside them the energy of mantras that have been read with them. There is an interesting story about the pray...

  4. Half bead welding technique

    International Nuclear Information System (INIS)

    Canonico, D.A.; Holz, P.P.

    1978-05-01

    The ORNL has employed the Section XI half-bead procedure for six repair welds. Table 2 identifies the repairs and the components upon which they were accomplished. The weld repairs were performed to permit us to evaluate material properties, residual stresses, weld repair procedures, and structural behavior of repaired pressure vessels. As a consequence of our study we concluded that when the half bead procedure is correctly applied: (1) there is no metallurgical degradation of the base material, (2) residual stresses of yield point magnitude will be present, and (3) the structural integrity of the pressure vessel is not impaired at Charpy V-notch upper shelf temperatures

  5. Superparamagnetic photocurable nanocomposite for the fabrication of microcantilevers

    DEFF Research Database (Denmark)

    Suter, M; Ergeneman, O; Zürcher, J

    2011-01-01

    We present a photocurable polymer composite with superparamagnetic characteristics for the fabrication of microcantilevers. Uniform distribution and low particle agglomeration (......We present a photocurable polymer composite with superparamagnetic characteristics for the fabrication of microcantilevers. Uniform distribution and low particle agglomeration (...

  6. Kinase-loaded magnetic beads for sequential in vitro phosphorylation of peptides and proteins.

    Science.gov (United States)

    Hromadkova, Lenka; Kupcik, Rudolf; Vajrychova, Marie; Prikryl, Petr; Charvatova, Andrea; Jankovicova, Barbora; Ripova, Daniela; Bilkova, Zuzana; Slovakova, Marcela

    2018-01-15

    Post-translational modifications, including phosphorylation, greatly impact the physiological function of proteins, especially those that are natively unfolded and implicated in many neurodegenerative diseases. However, structural and functional studies of such proteins require fully defined phosphorylation, including those that are not physiological. Thus, the kinases ERK2 and GSK-3β were immobilized to various superparamagnetic beads with carboxylic, aldehyde, Ni 2+ , or Co 3+ functional groups, with a view to efficiently phosphorylate peptides and proteins in vitro. Full phosphorylation of specific synthetic peptides confirmed that beads were successfully loaded with kinases. Remarkably, enzymes covalently immobilized on carboxylated SeraMag beads remained active upon reuse, with residual activity after 10 uses 99.5 ± 0.34% for GSK-3β and 36.2 ± 2.01% for ERK2. The beads were also used to sequentially phosphorylate recombinant tau, which in vivo is a biomarker of Alzheimer's disease. Thus, a system consisting of two fully active kinases immobilized to magnetic beads is demonstrated for the first time. In comparison to soluble enzymes, the beads are easier to handle, reusable, and thus low-cost. Importantly, these beads are also convenient to remove from reactions to minimize contamination of phosphorylated products or to exchange with other kinases.

  7. Microfluidic magnetic bead conveyor belt

    NARCIS (Netherlands)

    van Pelt, S.; Frijns, A.J.H.; den Toonder, J.M.J.

    2017-01-01

    Magnetic beads play an important role in the miniaturization of clinical diagnostics systems. In lab-on-chip platforms, beads can be made to link to a target species and can then be used for the manipulation and detection of this species. Current bead actuation systems utilize complex on-chip coil

  8. High frequency lateral flow affinity assay using superparamagnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lago-Cachón, D., E-mail: dlagocachon@gmail.com [Dpto. de Física, Universidad de Oviedo, Edificio Departamental Este, Campus de Viesques, 33204 Gijón (Spain); Rivas, M., E-mail: rivas@uniovi.es [Dpto. de Física, Universidad de Oviedo, Edificio Departamental Este, Campus de Viesques, 33204 Gijón (Spain); Martínez-García, J.C., E-mail: jcmg@uniovi.es [Dpto. de Física, Universidad de Oviedo, Edificio Departamental Este, Campus de Viesques, 33204 Gijón (Spain); Oliveira-Rodríguez, M., E-mail: oliveiramyriam@uniovi.es [Dpto. de Química Física y Analítica, Universidad de Oviedo, C/Julián Clavería 8, 33006 Oviedo (Spain); Blanco-López, M.C., E-mail: cblanco@uniovi.es [Dpto. de Química Física y Analítica, Universidad de Oviedo, C/Julián Clavería 8, 33006 Oviedo (Spain); García, J.A., E-mail: joseagd@uniovi.es [Dpto. de Física, Universidad de Oviedo, Escuela de Marina, Campus de Viesques, 33204 Gijón (Spain)

    2017-02-01

    Lateral flow assay is one of the simplest and most extended techniques in medical diagnosis for point-of-care testing. Although it has been traditionally a positive/negative test, some work has been lately done to add quantitative abilities to lateral flow assay. One of the most successful strategies involves magnetic beads and magnetic sensors. Recently, a new technique of superparamagnetic nanoparticle detection has been reported, based on the increase of the impedance induced by the nanoparticles on a RF-current carrying copper conductor. This method requires no external magnetic field, which reduces the system complexity. In this work, nitrocellulose membranes have been installed on the sensor, and impedance measurements have been carried out during the sample diffusion by capillarity along the membrane. The impedance of the sensor changes because of the presence of magnetic nanoparticles. The results prove the potentiality of the method for point-of-care testing of biochemical substances and nanoparticle capillarity flow studies. - Highlights: • A method for quantification of Lateral Flow Assays is proposed. • MNP induce an increase of the impedance on a RF-current carrying copper sensor. • Magnetic nanoparticles (MNP) can be detected flowing over the sensing element.

  9. High frequency lateral flow affinity assay using superparamagnetic nanoparticles

    International Nuclear Information System (INIS)

    Lago-Cachón, D.; Rivas, M.; Martínez-García, J.C.; Oliveira-Rodríguez, M.; Blanco-López, M.C.; García, J.A.

    2017-01-01

    Lateral flow assay is one of the simplest and most extended techniques in medical diagnosis for point-of-care testing. Although it has been traditionally a positive/negative test, some work has been lately done to add quantitative abilities to lateral flow assay. One of the most successful strategies involves magnetic beads and magnetic sensors. Recently, a new technique of superparamagnetic nanoparticle detection has been reported, based on the increase of the impedance induced by the nanoparticles on a RF-current carrying copper conductor. This method requires no external magnetic field, which reduces the system complexity. In this work, nitrocellulose membranes have been installed on the sensor, and impedance measurements have been carried out during the sample diffusion by capillarity along the membrane. The impedance of the sensor changes because of the presence of magnetic nanoparticles. The results prove the potentiality of the method for point-of-care testing of biochemical substances and nanoparticle capillarity flow studies. - Highlights: • A method for quantification of Lateral Flow Assays is proposed. • MNP induce an increase of the impedance on a RF-current carrying copper sensor. • Magnetic nanoparticles (MNP) can be detected flowing over the sensing element.

  10. Glass bead cultivation of fungi

    DEFF Research Database (Denmark)

    Droce, Aida; Sørensen, Jens Laurids; Giese, H.

    2013-01-01

    Production of bioactive compounds and enzymes from filamentous fungi is highly dependent on cultivation conditions. Here we present an easy way to cultivate filamentous fungi on glass beads that allow complete control of nutrient supply. Secondary metabolite production in Fusarium graminearum...... and Fusarium solani cultivated on agar plates, in shaking liquid culture or on glass beads was compared. Agar plate culture and glass bead cultivation yielded comparable results while liquid culture had lower production of secondary metabolites. RNA extraction from glass beads and liquid cultures was easier...... to specific nutrient factors. •Fungal growth on glass beads eases and improves fungal RNA extraction....

  11. Coated Aerogel Beads

    Science.gov (United States)

    Littman, Howard (Inventor); Plawsky, Joel L. (Inventor); Paccione, John D. (Inventor)

    2014-01-01

    Methods and apparatus for coating particulate material are provided. The apparatus includes a vessel having a top and a bottom, a vertically extending conduit having an inlet in the vessel and an outlet outside of the vessel, a first fluid inlet in the bottom of the vessel for introducing a transfer fluid, a second fluid inlet in the bottom of the vessel for introducing a coating fluid, and a fluid outlet from the vessel. The method includes steps of agitating a material, contacting the material with a coating material, and drying the coating material to produce a coated material. The invention may be adapted to coat aerogel beads, among other materials. A coated aerogel bead and an aerogel-based insulation material are also disclosed.

  12. Superparamagnetic relaxation of weakly interacting particles

    DEFF Research Database (Denmark)

    Mørup, Steen; Tronc, Elisabeth

    1994-01-01

    The influence of particle interactions on the superparamagnetic relaxation time has been studied by Mossbauer spectroscopy in samples of maghemite (gamma-Fe2O3) particles with different particle sizes and particle separations. It is found that the relaxation time decreases with decreasing particl...

  13. Superparamagnetic relaxation in alpha-Fe particles

    DEFF Research Database (Denmark)

    Bødker, Franz; Mørup, Steen; Pedersen, Michael Stanley

    1998-01-01

    The superparamagnetic relaxation time of carbon-supported alpha-Fe particles with an average size of 3.0 Mm has been studied over a large temperature range by the use of Mossbauer spectroscopy combined with AC and DC magnetization measurements. It is found that the relaxation time varies...

  14. Development and characterization of superparamagnetic coatings

    Directory of Open Access Journals (Sweden)

    Kuschnerus I.

    2015-09-01

    Full Text Available Since 2005, Magnetic Particle Imaging (MPI is handled as a key technology with great potential in medical applications as an imaging method [1]. The superparamagnetic iron oxide nanoparticles (SPIONs which are already used as a tracer in MPI, combined with various polymers, are being investigated in order to enhance this potential. A combination of polymers such as polyethylene (PE and polyurethane (PU and SPIONs could be used as a coating for medical devices, or added to semi-rigid polyurethane for the production of surgical instruments [2]. This would be of great interest, since the method provides high sensitivity with simultaneous high spatial resolution and three-dimensional imaging in real time. Therefore various superparamagnetic coatings were developed, tested and characterized. Finally SPIONs and various polymers were combined directly and used for MPI-compatible models.

  15. Development and characterization of superparamagnetic coatings

    OpenAIRE

    Kuschnerus I.; Lüdtke-Buzug K.

    2015-01-01

    Since 2005, Magnetic Particle Imaging (MPI) is handled as a key technology with great potential in medical applications as an imaging method [1]. The superparamagnetic iron oxide nanoparticles (SPIONs) which are already used as a tracer in MPI, combined with various polymers, are being investigated in order to enhance this potential. A combination of polymers such as polyethylene (PE) and polyurethane (PU) and SPIONs could be used as a coating for medical devices, or added to semi-rigid polyu...

  16. Superparamagnetic response of zinc ferrite incrusted nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Maldonado, K.L., E-mail: liliana.lopez.maldonado@gmail.com [Instituto de Ingeniería y Tecnología, Universidad Autónoma de Ciudad Juárez, Av. Del Charro 450 norte, 32310 Ciudad Juárez (Mexico); Presa, P. de la, E-mail: pmpresa@ucm.es [Instituto de Magnetismo Aplicado (UCM-ADIF-CSIC), PO Box 155, 28230 Las Rozas (Spain); Dpto. Física de Materiales, Univ. Complutense de Madrid, Madrid (Spain); Betancourt, I., E-mail: israelb@unam.mx [Departamento de Materiales Metálicos y Cerámicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México, D.F. 04510 (Mexico); Farias Mancilla, J.R., E-mail: rurik.farias@uacj.mx [Instituto de Ingeniería y Tecnología, Universidad Autónoma de Ciudad Juárez, Av. Del Charro 450 norte, 32310 Ciudad Juárez (Mexico); Matutes Aquino, J.A., E-mail: jose.matutes@cimav.edu.mx [Centro de Investigación en Materiales Avanzados, Miguel de Cervantes 120, 31109 Chihuahua (Mexico); Hernando, A., E-mail: antonio.hernando@externos.adif.es [Instituto de Magnetismo Aplicado (UCM-ADIF-CSIC), PO Box 155, 28230 Las Rozas (Spain); Dpto. Física de Materiales, Univ. Complutense de Madrid, Madrid (Spain); and others

    2015-07-15

    Highlights: • Incrusted nanoparticles are found at the surface of ZnFe{sub 2}O{sub 4} microparticles. • Magnetic contribution of nano and microparticles are analyzed by different models. • Langevin model is used to calculate the nanoparticles-superparamagnetic diameter. • Susceptibility and Langevin analysis and calculations agree with experimental data. - Abstract: Zinc ferrite is synthesized via mechano-activation, followed by thermal treatment. Spinel ZnFe{sub 2}O{sub 4} single phase is confirmed by X-ray diffraction. SEM micrographs show large particles with average particle size 〈D{sub part}〉 = 1 μm, with particles in intimate contact. However, TEM micrographs show incrusted nanocrystallites at the particles surface, with average nanocrystallite size calculated as 〈D{sub inc}〉 ≈ 5 nm. The blocking temperature at 118 K in the ZFC–FC curves indicates the presence of a superparamagnetic response which is attributable to the incrusted nanocrystallites. Moreover, the hysteresis loops show the coexistence of superpara- and paramagnetic responses. The former is observable at the low field region; meanwhile, the second one is responsible of the lack of saturation at high field region. This last behavior is related to a paramagnetic contribution coming from well-ordered crystalline microdomains. The hysteresis loops are analyzed by means of two different models. The first one is the susceptibility model used to examine separately the para- and superparamagnetic contributions. The fittings with the theoretical model confirm the presence of the above mentioned magnetic contributions. Finally, using the Langevin-based model, the average superparamagnetic diameter 〈D{sub SPM}〉 is calculated. The obtained value 〈D{sub SPM}〉 = 4.7 nm (∼5 nm) is consistent with the average nanocrystallite size observed by TEM.

  17. Microfabricated Passive Magnetic Bead separators

    DEFF Research Database (Denmark)

    Hansen, Mikkel Fougt; Lund-Olesen, Torsten; Smistrup, Kristian

    2006-01-01

    The use and manipulation of functionalized magnetic beads for bioanalysis in lab-on-a-chip systems is receiving growing interest. We have developed microfluidic systems with integrated magnetic structures for the capture and release of magnetic beads. The systems are fabricated in silicon by deep...

  18. bEADS

    DEFF Research Database (Denmark)

    Williams, Peter Leslie; Overholt, Daniel

    2017-01-01

    While there are a great variety of digital musical interfaces available to the working musician, few offer the level of immediate, nuanced and instinctive interaction that one finds in an acoustic shaker. bEADS is a prototype of a digital musical instrument that utilises the gestural vocabulary...... associated with shaken idiophones and expands on the techniques and sonic possibilities associated with them. By using a bespoke physically informed synthesis engine, in conjunction with accelerometer and pressure sensor data, an actuated handheld instrument has been built that allows for quickly switching...... between widely differing percussive sound textures. The prototype has been evaluated by three experts with different levels of involvement in professional music making....

  19. Nonlinear Parametric Excitation Effect Induces Stability Transitions in Swimming Direction of Flexible Superparamagnetic Microswimmers.

    Science.gov (United States)

    Harduf, Yuval; Jin, Dongdong; Or, Yizhar; Zhang, Li

    2018-04-05

    Microscopic artificial swimmers have recently become highly attractive due to their promising potential for biomedical microrobotic applications. Previous pioneering work has demonstrated the motion of a robotic microswimmer with a flexible chain of superparamagnetic beads, which is actuated by applying an oscillating external magnetic field. Interestingly, they have shown that the microswimmer's orientation undergoes a 90°-transition when the magnetic field's oscillation amplitude is increased above a critical value. This unexpected transition can cause severe problems in steering and manipulation of flexible magnetic microrobotic swimmers. Thus, theoretical understanding and analysis of the physical origins of this effect are of crucial importance. In this work, we investigate this transition both theoretically and experimentally by using numerical simulations and presenting a novel flexible microswimmer with an anisotropic superparamagnetic head. We prove that this effect depends on both frequency and amplitude of the oscillating magnetic field, and demonstrate existence of an optimal amplitude achieving maximal swimming speed. Asymptotic analysis of a minimal two-link model reveals that the changes in the swimmer's direction represent stability transitions, which are induced by a nonlinear parametric excitation.

  20. Synthesis and characterization of superparamagnetic polymeric nanocapsules

    Energy Technology Data Exchange (ETDEWEB)

    Grillo, Renato; Fraceto, Leonardo Fernandes, E-mail: renato.grillo@ymail.com [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Sorocaba, SP (Brazil); Gallo, Juan; Grando Stroppa, Daniel; Carbo-Argibay, Enrique; Banõbre-Lopez, Manuel [International Iberian Nanotechnology Laboratory, Braga (Portugal); Lima, Renata de [Universidade de Sorocaba (UNISO), SP (Brazil)

    2016-07-01

    Full text: A wide variety of applications have been considered for superparamagnetic iron oxide nanoparticles (SPIONs), such as magnetic resonance imaging, cancer therapy and remediation of contaminants [1].Polymeric nanostructures (PNS) have also received great interest as suitable encapsulating agents and carriers due to their ability to influence the delivery profile. Hybrid nanosystems have been explored as a synergic approach that combines the modified active release induced by the polymer encapsulation and the intrinsic properties from the inorganic nanoparticles [2]. In this context, poly-ε-caprolactone nanocapsules containing different concentration of ∼8 nm superparamagnetic oleic acid coated magnetite (Fe{sub 3}O{sub 4}@OA) nanoparticles were developed. Successful incorporation of the magnetic nanoparticles was confirmed by transmission electron microscopy coupled with energy dispersive X-ray (TEM-EDX). Results showed that they accumulate preferentially in the outer organic membrane of the PNS. On the other hand, scanning electron microscopy and dynamic light scattering measurements showed a significant increase in particle size from ca. 400 to 800 nm. Magnetic measurements as a function of the applied magnetic field and temperature were performed in both vibrant sample (VSM) and superconducting quantum interference device magnetometers (SQUID). Hysteresis loops showed a superparamagnetic behavior with increasing saturation magnetization as magnetite concentration was progressively incorporated into the PNS. Zero-field cooled and field-cooled (ZFC-FC) magnetic curves showed a shift of the blocking temperature to higher temperatures as the content of magnetite increases in the capsules. These results are promising and contribute to a better understanding of the interaction between magnetic nanoparticles and PNS. References: [1] L. Zhang, W. Dong, H. Sun. Nanoscale 5, 7664-7684 (2013) [2] K.T. Nguyen and Y.L. Zhao. Acc. Chem. Res. 48, 3016-3025 (2015

  1. Synthesis of magnetic hollow silica using polystyrene bead as a template

    International Nuclear Information System (INIS)

    Wu, W.; Caruntu, D.; Martin, A.; Yu, M.H.; O'Connor, C.J.; Zhou, W.L.; Chen, J.-F.

    2007-01-01

    In this paper, we report a new route to synthesize novel magnetic hollow silica nanospheres (MHSNs) using polystyrene particles as sacrificial templates, and TEOS and Fe 3 O 4 as precursors. TEM, EDS, XRD, and SQUID were applied to characterize MHSNs. TEM and EDS results show that the MHSNs consist of about 200 nm of hollow cores and ∼35 nm shells with ∼10 nm of Fe 3 O 4 nanoparticles embedded. The polystyrene beads were successfully removed by immersing the as-prepared silica nanocomposite in a toluene solution. XRD results demonstrate that the Fe 3 O 4 magnetic nanoparticles still keep spinel structure even heated at low temperature. The surface status of the polystyrene beads and Fe 3 O 4 nanoparticles has an important effect on the formation of the MHSNs. The MHSNs present a superparamagnetism at room temperature by SQUID measurement. The MHSNs have potential applications in biosystem and nanomedicine

  2. A half-ring GMR sensor for detection of magnetic beads immobilized on a circular micro-trap

    KAUST Repository

    Gooneratne, Chinthaka Pasan

    2011-11-01

    Utilizing magnetic principles in biological immunoassays is an attractive option given its ability to remotely and non-invasively manipulate and detect cells tagged with micro/nano size superparamagnetic type beads and due to the fact that even the most complex biological immunoassays will have very little magnetic effect. The presence of magnetic beads can be detected by a magnetic sensor which quantifies the amount of target cells present in the immunoassay. In order to increase the detection rate a circular conducting micro-trap is employed to attract, trap and transport the magnetic beads to the sensing area. In this research we propose a half-ring spin valve type giant magnetoresistance (GMR) sensor for the measurement of stray fields produced by 2 μm magnetic beads which are around the circular micro-trap. A couple of half-ring GMR sensors can be used to cover the entire circular border width, in order to detect the majority of the immobilized magnetic beads. Analytical and numerical analysis leading towards the fabrication of the half-ring GMR sensor are presented. DC characterization of the fabricated sensor showed a magnetoresistance of 5.9 %. Experimental results showed that the half-ring GMR sensor detected the presence of 2 μm magnetic beads. Hence, half-ring GMR sensors integrated with a circular micro-trap have great potential to be used as an effective disease diagnostic device. © 2011 IEEE.

  3. A half-ring GMR sensor for detection of magnetic beads immobilized on a circular micro-trap

    KAUST Repository

    Gooneratne, Chinthaka Pasan; Liang, Cai; Useinov, Arthur; Kosel, Jü rgen; Giouroudi, Ioanna

    2011-01-01

    Utilizing magnetic principles in biological immunoassays is an attractive option given its ability to remotely and non-invasively manipulate and detect cells tagged with micro/nano size superparamagnetic type beads and due to the fact that even the most complex biological immunoassays will have very little magnetic effect. The presence of magnetic beads can be detected by a magnetic sensor which quantifies the amount of target cells present in the immunoassay. In order to increase the detection rate a circular conducting micro-trap is employed to attract, trap and transport the magnetic beads to the sensing area. In this research we propose a half-ring spin valve type giant magnetoresistance (GMR) sensor for the measurement of stray fields produced by 2 μm magnetic beads which are around the circular micro-trap. A couple of half-ring GMR sensors can be used to cover the entire circular border width, in order to detect the majority of the immobilized magnetic beads. Analytical and numerical analysis leading towards the fabrication of the half-ring GMR sensor are presented. DC characterization of the fabricated sensor showed a magnetoresistance of 5.9 %. Experimental results showed that the half-ring GMR sensor detected the presence of 2 μm magnetic beads. Hence, half-ring GMR sensors integrated with a circular micro-trap have great potential to be used as an effective disease diagnostic device. © 2011 IEEE.

  4. Microfluidic magnetic bead conveyor belt.

    Science.gov (United States)

    van Pelt, Stijn; Frijns, Arjan; den Toonder, Jaap

    2017-11-07

    Magnetic beads play an important role in the miniaturization of clinical diagnostics systems. In lab-on-chip platforms, beads can be made to link to a target species and can then be used for the manipulation and detection of this species. Current bead actuation systems utilize complex on-chip coil systems that offer low field strengths and little versatility. We demonstrate a novel system based on an external rotating magnetic field and on-chip soft-magnetic structures to focus the field locally. These structures were designed and optimized using finite element simulations in order to create a number of local flux density maxima. These maxima, to which the magnetic beads are attracted, move over the chip surface in a continuous way together with the rotation of the external field, resulting in a mechanism similar to that of a conveyor belt. A prototype was fabricated using PDMS molding techniques mixed with iron powder for the magnetic structures. In the subsequent experiments, a quadrupole electromagnet was used to create the rotating external field. We observed that beads formed agglomerates that rolled over the chip surface, just above the magnetic structures. Field rotation frequencies between 0.1-50 Hz were tested resulting in magnetic bead speeds of over 1 mm s -1 for the highest frequency. With this, we have shown that our novel concept works, combining a simple design and simple operation with a powerful and versatile method for bead actuation. This makes it a promising method for further research and utilization in lab-on-chip systems.

  5. Permanent magnet system to guide superparamagnetic particles

    Science.gov (United States)

    Baun, Olga; Blümler, Peter

    2017-10-01

    A new concept of using permanent magnet systems for guiding superparamagnetic nano-particles on arbitrary trajectories over a large volume is proposed. The basic idea is to use one magnet system which provides a strong, homogeneous, dipolar magnetic field to magnetize and orient the particles, and a second constantly graded, quadrupolar field, superimposed on the first, to generate a force on the oriented particles. In this configuration the motion of the particles is driven predominantly by the component of the gradient field which is parallel to the direction of the homogeneous field. As a result, particles are guided with constant force and in a single direction over the entire volume. The direction is simply adjusted by varying the angle between quadrupole and dipole. Since a single gradient is impossible due to Gauß' law, the other gradient component of the quadrupole determines the angular deviation of the force. However, the latter can be neglected if the homogeneous field is stronger than the local contribution of the quadrupole field. A possible realization of this idea is a coaxial arrangement of two Halbach cylinders. A dipole to evenly magnetize and orient the particles, and a quadrupole to generate the force. The local force was calculated analytically for this particular geometry and the directional limits were analyzed and discussed. A simple prototype was constructed to demonstrate the principle in two dimensions on several nano-particles of different size, which were moved along a rough square by manual adjustment of the force angle. The observed velocities of superparamagnetic particles in this prototype were always several orders of magnitude higher than the theoretically expected value. This discrepancy is attributed to the observed formation of long particle chains as a result of their polarization by the homogeneous field. The magnetic moment of such a chain is then the combination of that of its constituents, while its hydrodynamic radius

  6. Magnetic susceptibility characterisation of superparamagnetic microspheres

    Science.gov (United States)

    Grob, David Tim; Wise, Naomi; Oduwole, Olayinka; Sheard, Steve

    2018-04-01

    The separation of magnetic materials in microsystems using magnetophoresis has increased in popularity. The wide variety and availability of magnetic beads has fuelled this drive. It is important to know the magnetic characteristics of the microspheres in order to accurately use them in separation processes integrated on a lab-on-a-chip device. To investigate the magnetic susceptibility of magnetic microspheres, the magnetic responsiveness of three types of Dynabeads microspheres were tested using two different approaches. The magnetophoretic mobility of individual microspheres is studied using a particle tracking system and the magnetization of each type of Dynabeads microsphere is measured using SQUID relaxometry. The magnetic beads' susceptibility is obtained at four different applied magnetic fields in the range of 38-70 mT for both the mobility and SQUID measurements. The susceptibility values in both approaches show a consistent magnetic field dependence.

  7. Washing effect on superparamagnetic iron oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Laura-Karina Mireles

    2016-06-01

    Full Text Available Much recent research on nanoparticles has occurred in the biomedical area, particularly in the area of superparamagnetic iron oxide nanoparticles (SPIONs; one such area of research is in their use as magnetically directed prodrugs. It has been reported that nanoscale materials exhibit properties different from those of materials in bulk or on a macro scale [1]. Further, an understanding of the batch-to-batch reproducibility and uniformity of the SPION surface is essential to ensure safe biological applications, as noted in the accompanying article [2], because the surface is the first layer that affects the biological response of the human body. Here, we consider a comparison of the surface chemistries of a batch of SPIONs, before and after the supposedly gentle process of dialysis in water.

  8. Disposal of bead ion exchange resin wastes

    International Nuclear Information System (INIS)

    Gay, R.L.; Granthan, L.F.

    1985-01-01

    Bead ion exchange resin wastes are disposed of by a process which involves spray-drying a bead ion exchange resin waste in order to remove substantially all of the water present in such waste, including the water on the surface of the ion exchange resin beads and the water inside the ion exchange resin beads. The resulting dried ion exchange resin beads can then be solidified in a suitable solid matrix-forming material, such as a polymer, which solidifies to contain the dried ion exchange resin beads in a solid monolith suitable for disposal by burial or other conventional means

  9. A novel superparamagnetic surface molecularly imprinted nanoparticle adopting dummy template: an efficient solid-phase extraction adsorbent for bisphenol A.

    Science.gov (United States)

    Lin, Zhenkun; Cheng, Wenjing; Li, Yanyan; Liu, Zhiren; Chen, Xiangping; Huang, Changjiang

    2012-03-30

    Leakage of the residual template molecules is one of the biggest challenges for application of molecularly imprinted polymer (MIP) in solid-phase extraction (SPE). In this study, bisphenol F (BPF) was adopted as a dummy template to prepare MIP of bisphenol A (BPA) with a superparamagnetic core-shell nanoparticle as the supporter, aiming to avoid residual template leakage and to increase the efficiency of SPE. Characterization and test of the obtained products (called mag-DMIP beads) revealed that these novel nanoparticles not only had excellent magnetic property but also displayed high selectivity to the target molecule BPA. As mag-DMIP beads were adopted as the adsorbents of solid-phase extraction for detecting BPA in real water samples, the recoveries of spiked samples ranged from 84.7% to 93.8% with the limit of detection of 2.50 pg mL(-1), revealing that mag-DMIP beads were efficient SPE adsorbents. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Calibration beads containing luminescent lanthanide ion complexes

    Science.gov (United States)

    The reliability of lanthanide luminescence measurements, by both flow cytometry and digital microscopy, will be enhanced by the availability of narrow-band emitting lanthanide calibration beads. These beads can also be used to characterize spectrographic instruments, including mi...

  11. Three-bead steering microswimmers

    Science.gov (United States)

    Rizvi, Mohd Suhail; Farutin, Alexander; Misbah, Chaouqi

    2018-02-01

    The self-propelled microswimmers have recently attracted considerable attention as model systems for biological cell migration as well as artificial micromachines. A simple and well-studied microswimmer model consists of three identical spherical beads joined by two springs in a linear fashion with active oscillatory forces being applied on the beads to generate self-propulsion. We have extended this linear microswimmer configuration to a triangular geometry where the three beads are connected by three identical springs in an equilateral triangular manner. The active forces acting on each spring can lead to autonomous steering motion; i.e., allowing the swimmer to move along arbitrary paths. We explore the microswimmer dynamics analytically and pinpoint its rich character depending on the nature of the active forces. The microswimmers can translate along a straight trajectory, rotate at a fixed location, as well as perform a simultaneous translation and rotation resulting in complex curved trajectories. The sinusoidal active forces on the three springs of the microswimmer contain naturally four operating parameters which are more than required for the steering motion. We identify the minimal operating parameters which are essential for the motion of the microswimmer along any given arbitrary trajectory. Therefore, along with providing insights into the mechanics of the complex motion of the natural and artificial microswimmers, the triangular three-bead microswimmer can be utilized as a model for targeted drug delivery systems and autonomous underwater vehicles where intricate trajectories are involved.

  12. Design of Superparamagnetic Nanoparticles for Magnetic Particle Imaging (MPI

    Directory of Open Access Journals (Sweden)

    Philip W. T. Pong

    2013-09-01

    Full Text Available 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.

  13. Microstructural Study on Oxygen Permeated Arc Beads

    Directory of Open Access Journals (Sweden)

    Kuan-Heng Liu

    2015-01-01

    Full Text Available We simulated short circuit of loaded copper wire at ambient atmosphere and successfully identified various phases of the arc bead. A cuprous oxide flake was formed on the surface of the arc bead in the rapid solidification process, and there were two microstructural constituents, namely, Cu-κ eutectic structure and solutal dendrites. Due to the arc bead formed at atmosphere during the local equilibrium solidification process, the phase of arc bead has segregated to the cuprous oxide flake, Cu-κ eutectic, and Cu phase solutal dendrites, which are the fingerprints of the arc bead permeated by oxygen.

  14. Magnetic bead detection using nano-transformers

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyung Kwon; Ahn, Doyeol [Institute of Quantum Information Processing and Systems, University of Seoul, 90 Jeonnong, Dongdaemun, Seoul 130-743 (Korea, Republic of); Hwang, Jong Seung; Hwang, Sung Woo, E-mail: dahn@uos.ac.kr [Research Center for Time-domain Nano-functional Devices and School of Electrical Engineering, Korea University, 5-1 Anam, Sungbuk, Seoul 136-701 (Korea, Republic of)

    2010-11-19

    A novel scheme to detect magnetic beads using a nano-scale transformer with a femtoweber resolution is reported. We have performed a Faraday's induction experiment with the nano-transformer at room temperature. The transformer shows the linear output voltage responses to the sinusoidal input current. When magnetic beads are placed on the transformer, the output responses are increased by an amount corresponding to the added magnetic flux from the beads when compared with the case of no beads on the transformer. In this way, we could determine whether magnetic beads are on top of the transformer in a single particle level.

  15. Magnetic bead detection using nano-transformers.

    Science.gov (United States)

    Kim, Hyung Kwon; Hwang, Jong Seung; Hwang, Sung Woo; Ahn, Doyeol

    2010-11-19

    A novel scheme to detect magnetic beads using a nano-scale transformer with a femtoweber resolution is reported. We have performed a Faraday's induction experiment with the nano-transformer at room temperature. The transformer shows the linear output voltage responses to the sinusoidal input current. When magnetic beads are placed on the transformer, the output responses are increased by an amount corresponding to the added magnetic flux from the beads when compared with the case of no beads on the transformer. In this way, we could determine whether magnetic beads are on top of the transformer in a single particle level.

  16. Direct friction measurement in draw bead testing

    DEFF Research Database (Denmark)

    Olsson, David Dam; Bay, Niels; Andreasen, Jan Lasson

    2005-01-01

    The application of draw beads in sheet metal stamping ensures controlled drawing-in of flange parts. Lubrication conditions in draw beads are severe due to sliding under simultaneous bending. Based on the original draw bead test design by Nine [1] comprehensive studies of friction in draw beads...... have been reported in literature. A major drawback in all these studies is that friction is not directly measured, but requires repeated measurements of the drawing force with and without relative sliding between the draw beads and the sheet material. This implies two tests with a fixed draw bead tool...... and a freely rotating tool respectively, an approach, which inevitably implies large uncertainties due to scatter in the experimental conditions. In order to avoid this problem a new draw bead test is proposed by the authors measuring the friction force acting on the tool radius directly by a build...

  17. Developement of Spherical Polyurethane Beads

    Institute of Scientific and Technical Information of China (English)

    K. Maeda; H. Ohmori; H. Gyotoku

    2005-01-01

    @@ 1Results and Discussion We established a new method to produce the spherical polyurethane beads which have narrower distribution of particle size. This narrower distribution was achieved by the polyurethane prepolymer which contains ketimine as a blocked chain-extending agent. Firstly, the prepolymer is dispersed into the aqueous solution containing surfactant. Secondaly, water comes into the inside of prepolymer as oil phase. Thirdly, ketimine is hydrolyzed to amine, and amine reacts with prepolymer immediately to be polyurethane.Our spherical polyurethane beads are very suitable for automotive interior parts especially for instrument panel cover sheet producing under the slush molding method, because of good process ability, excellent durability to the sunlight and mechanical properties at low temperature. See Fig. 1 ,Fig. 2 and Fig. 3 (Page 820).

  18. Acceleration of superparamagnetic particles with magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Stange, R., E-mail: Robert.stange@tu-dresden.de; Lenk, F.; Bley, T.; Boschke, E.

    2017-04-01

    High magnetic capture efficiency in the context of Biomagnetic Separation (BMS) using superparamagnetic particles (SMPs) requires efficient mixing and high relative velocities between cellular and other targets and SMPs. For this purpose, batch processes or microfluidic systems are commonly used. Here, we analyze the characteristics of an in-house developed batch process experimental setup, the Electromagnetic Sample Mixer (ESM) described earlier. This device uses three electromagnets to increase the relative velocity between SMPs and targets. We carry out simulations of the magnetic field in the ESM and in a simpler paradigmatic setup, and thus were able to calculate the force field acting on the SMPs and to simulate their relative velocities and fluid dynamics due to SMP movement. In this way we were able to show that alternate charging of the magnets induces a double circular stream of SMPs in the ESM, resulting in high relative velocities of SMPs to the targets. Consequently, due to the conservation of momentum, the fluid experiences an acceleration induced by the SMPs. We validated our simulations by microscopic observation of the SMPs in the magnetic field, using a homemade apparatus designed to accommodate a long working-distance lens. By comparing the results of modeling this paradigmatic setup with the experimental observations, we determined that the velocities of the SMPs corresponded to the results of our simulations. - Highlights: • Investigation of a batch process setup for complex forming at Biomagnetic Separation. • Simulation of fluid flow characteristics in this Electro Magnetic Samplemixer. • Simulation of relative velocities between magnetic particles and fluid in the setup. • Simulation of fluid flow induced by the acceleration of magnet particles. • Validation of magnetic fields and flow characteristics in paradigmatic setups. • Reached relative velocity is higher than the sedimentation velocity of the particles • Alternating

  19. Plasma Antenna Based on Superparamagnetic Nanoparticles

    Science.gov (United States)

    Papadopoulos, K.

    2017-12-01

    A novel plasma antenna for space or ground based generation and injection of whistler and Alfven waves is presented. The new antenna concept is based on recently manufactured, small (10-60 nm radius), single domain, non-interacting magnetic grains with uniaxial magnetic anisotropy, known as superparamagnetic nanoparticles (SPN), dispersed in low viscosity, non-conducting media. SPNs can be described as ensembles of non-interacting magnetic moments μ with energy E=-μB when driven by a magnetic field B, similar to ordinary paramagnets, with exception that SPNs are composed by many thousands of magnetic atoms and as result have susceptibilities comparable to ferromagnets but with zero coercivity. The Langevin function accurately describes the dynamic behavior of the magnetization in the presence of low frequency AC fields since the characteristic mechanical (Brownian) and magnetic (Neel) relaxation times are shorter than 10msecs. For ground-based applications the grains are suspended in low viscosity carrier liquids, such as water or benzne and are known as ferrofluids. For space based applications, such as wave injection from CubeSats they can be dispersed as dust in vacuum containers. Agglomeration is avoided by coating the grains by coating their surface by an appropriate surfactant molecule. The ensemble of magnetic grains is driven to rotation at the desired VLF or ELF frequency by a pair of Helmholtz like coils surrounding the grain container. The near field electric field associated with rotating magnetic field then drives currents such as were observed in Rotating Magnetic Field experiments at the UCLA/LAPD chamber [Gigliotti et al., Phys. of Plasmas 16:092106; Karavaev et al., Phys. of Plasmas 17(1):012102,2010]. The magnetic moment of the AC coil is amplified by the susceptibility χ of the SPN ensemble that depending on the grain size and material can reach values of 104-105. Preliminary estimates indicate that less than 1 kg of SPN grains and power of

  20. Comparison of non-magnetic and magnetic beads in bead-based assays

    NARCIS (Netherlands)

    Hansenová Maňásková, S.; van Belkum, A.; Endtz, H.P.; Bikker, F.J.; Veerman, E.C.I.; van Wamel, W.J.B.

    2016-01-01

    Multiplex bead-based flow cytometry is an attractive way for simultaneous, rapid and cost-effective analysis of multiple analytes in a single sample. Previously, we developed various bead-based assays using non-magnetic beads coated with Staphylococcus aureus and Streptococcus pneumoniae antigens

  1. Beautiful Beads: A Lesson in Making Beads with Friendly Clay. AMACO[R] Lesson.

    Science.gov (United States)

    Gamble, Harriet; Gamble, David

    This lesson resource includes a brief summary of the history of bead making and historic fascination with beads as adornment. A focus on design elements, color theory, craftsmanship, and technical skill in bead making is encouraged. The plan includes lesson goals and objectives; background preparation; a glossary of terms; a list of supplies; and…

  2. A giant magnetoresistance ring-sensor based microsystem for magnetic bead manipulation and detection

    KAUST Repository

    Gooneratne, Chinthaka P.

    2011-03-28

    In this paper a novel spin valvegiant magnetoresistance(GMR) ring-sensor integrated with a microstructure is proposed for concentrating, trapping, and detecting superparamagnetic beads (SPBs). Taking advantage of the fact that SPBs can be manipulated by an external magnetic field, a unique arrangement of conducting microrings is utilized to manipulate the SPBs toward the GMR sensing area in order to increase the reliability of detection. The microrings are arranged and activated in such a manner so as to enable the detection of minute concentrations of SPBs in a sample. Precise manipulation is achieved by applying current sequentially to the microrings. The fabricated ring-shaped GMR element is located underneath the innermost ring and has a magnetoresistance of approximately 5.9%. By the performed experiments it was shown that SPBs could be successfully manipulated toward the GMR sensing zone.

  3. A giant magnetoresistance ring-sensor based microsystem for magnetic bead manipulation and detection

    KAUST Repository

    Gooneratne, Chinthaka P.; Giouroudi, Ioanna; Liang, Cai; Kosel, Jü rgen

    2011-01-01

    In this paper a novel spin valvegiant magnetoresistance(GMR) ring-sensor integrated with a microstructure is proposed for concentrating, trapping, and detecting superparamagnetic beads (SPBs). Taking advantage of the fact that SPBs can be manipulated by an external magnetic field, a unique arrangement of conducting microrings is utilized to manipulate the SPBs toward the GMR sensing area in order to increase the reliability of detection. The microrings are arranged and activated in such a manner so as to enable the detection of minute concentrations of SPBs in a sample. Precise manipulation is achieved by applying current sequentially to the microrings. The fabricated ring-shaped GMR element is located underneath the innermost ring and has a magnetoresistance of approximately 5.9%. By the performed experiments it was shown that SPBs could be successfully manipulated toward the GMR sensing zone.

  4. Moessbauer studies of superparamagnetic ferrite nanoparticles for functional application

    Energy Technology Data Exchange (ETDEWEB)

    Mazeika, K., E-mail: kestas@ar.fi.lt; Jagminas, A.; Kurtinaitiene, M. [SSRI Center for Physical Sciences and Technology (Lithuania)

    2013-04-15

    Nanoparticles of CoFe{sub 2}O{sub 4} and MnFe{sub 2}O{sub 4} prepared for functional applications in nanomedicine were studied using Moessbauer spectrometry. Superparamagnetic properties of nanoparticles of different size and composition were compared applying collective excitations and multilevel models for the description of the Moessbauer spectra.

  5. Magnetic tweezers with high permeability electromagnets for fast actuation of magnetic beads

    Energy Technology Data Exchange (ETDEWEB)

    Chen, La; Offenhäusser, Andreas; Krause, Hans-Joachim [Institute of Bioelectronics (ICS-8/PGI-8), Forschungszentrum Jülich GmbH, 52425 Jülich (Germany)

    2015-04-15

    As a powerful and versatile scientific instrument, magnetic tweezers have been widely used in biophysical research areas, such as mechanical cell properties and single molecule manipulation. If one wants to steer bead position, the nonlinearity of magnetic properties and the strong position dependence of the magnetic field in most magnetic tweezers lead to quite a challenge in their control. In this article, we report multi-pole electromagnetic tweezers with high permeability cores yielding high force output, good maneuverability, and flexible design. For modeling, we adopted a piece-wise linear dependence of magnetization on field to characterize the magnetic beads. We implemented a bi-linear interpolation of magnetic field in the work space, based on a lookup table obtained from finite element simulation. The electronics and software were custom-made to achieve high performance. In addition, the effects of dimension and defect on structure of magnetic tips also were inspected. In a workspace with size of 0.1 × 0.1 mm{sup 2}, a force of up to 400 pN can be applied on a 2.8 μm superparamagnetic bead in any direction within the plane. Because the magnetic particle is always pulled towards a tip, the pulling forces from the pole tips have to be well balanced in order to achieve control of the particle’s position. Active video tracking based feedback control is implemented, which is able to work at a speed of up to 1 kHz, yielding good maneuverability of the magnetic beads.

  6. Streptavidin-coated gold nanoparticles: critical role of oligonucleotides on stability and fractal aggregation

    Directory of Open Access Journals (Sweden)

    Roberta D'Agata

    2017-01-01

    Full Text Available Gold nanoparticles (AuNPs exhibit unique properties that can be modulated through a tailored surface functionalization, enabling their targeted use in biochemical sensing and medical diagnostics. In particular, streptavidin-modified AuNPs are increasingly used for biosensing purposes. We report here a study of AuNPs surface-functionalized with streptavidin-biotinylated oligonucleotide, focussing on the role played by the oligonucleotide probes in the stabilization/destabilization of the functionalized nanoparticle dispersion. The behaviour of the modified AuNP dispersion as a consequence of the competitive displacement of the biotinylated oligonucleotide has been investigated and the critical role of displaced oligonucletides in triggering the quasi one-dimensional aggregation of nanoparticles is demonstrated for the first time. The thorough understanding of the fundamental properties of bioconjugated AuNPs is of great importance for the design of highly sensitive and reliable functionalized AuNP-based assays.

  7. Fused Bead Analysis of Diogenite Meteorites

    Science.gov (United States)

    Mittlefehldt, D.W.; Beck, B.W.; McSween, H.Y.; Lee, C.T. A.

    2009-01-01

    Bulk rock chemistry is an essential dataset in meteoritics and planetary science [1]. A common method used to obtain the bulk chemistry of meteorites is ICP-MS. While the accuracy, precision and low detection limits of this process are advantageous [2], the sample size used for analysis (approx.70 mg) can be a problem in a field where small and finite samples are the norm. Fused bead analysis is another bulk rock analytical technique that has been used in meteoritics [3]. This technique involves forming a glass bead from 10 mg of sample and measuring its chemistry using a defocused beam on a microprobe. Though the ICP-MS has lower detection limits than the microprobe, the fused bead method destroys a much smaller sample of the meteorite. Fused bead analysis was initially designed for samples with near-eutectic compositions and low viscosities. Melts generated of this type homogenize at relatively low temperatures and produce primary melts near the sample s bulk composition [3]. The application of fused bead analysis to samples with noneutectic melt compositions has not been validated. The purpose of this study is to test if fused bead analysis can accurately determine the bulk rock chemistry of non-eutectic melt composition meteorites. To determine this, we conduct two examinations of the fused bead. First, we compare ICP-MS and fused bead results of the same samples using statistical analysis. Secondly, we inspect the beads for the presence of crystals and chemical heterogeneity. The presence of either of these would indicate incomplete melting and quenching of the bead.

  8. Using permalloy based planar hall effect sensors to capture and detect superparamagnetic beads for lab on a chip applications

    International Nuclear Information System (INIS)

    Volmer, Marius; Avram, Marioara

    2015-01-01

    Experimental studies have been carried out on planar Hall effect (PHE) sensors used to detect magnetic nanoparticles employed as labels for biodetection applications. Disk shaped sensors, 1 mm diameter, were structured on Permalloy film, 20 nm thick. To control the sensor magnetisation state and thus the field sensitivity and linearity, a DC biasing field has been applied parallel to the driving current. Maghemite nanoparticles (10 nm) functionalised with Polyethylene glycol (PEG) 6000 were immobilised over the sensor surface using particular magnetisation state and applied magnetic fields. In order to obtain a higher response from the magnetic nanoparticles, it was used a detection setup which allows the application of magnetic fields larger than 100 Oe but avoiding saturation of the PHE signal. Based on this setup, two field scanning methods are presented in this paper. During our experiments, low magnetic moments, of about 1.87×10 −5 emu, have been easily detected. This value corresponds to a mass of 9.35 µg of maghemite nanoparticles functionalised with PEG 6000. The results suggest that this type of structure is feasible for building low cost micrometer sized PHE sensors to be used for high-resolution bio sensing applications. - Highlights: • Disk-shaped Permalloy planar Hall effect sensors have been obtained and tested. • Two field scanning methods have been proposed. • The magnetic nanoparticles can be trapped on the sensor surface. • High detection sensitivity has been obtained

  9. Near-infrared-responsive, superparamagnetic Au@Co nanochains

    Directory of Open Access Journals (Sweden)

    Varadee Vittur

    2017-08-01

    Full Text Available This manuscript describes a new type of nanomaterial, namely superparamagnetic Au@Co nanochains with optical extinctions in the near infrared (NIR. The Au@Co nanochains were synthesized via a one-pot galvanic replacement route involving a redox-transmetalation process in aqueous medium, where Au salt was reduced to form Au shells on Co seed templates, affording hollow Au@Co nanochains. The Au shells serve not only as a protective coating for the Co nanochain cores, but also to give rise to the optical properties of these unique nanostructures. Importantly, these bifunctional, magneto-optical Au@Co nanochains combine the advantages of nanophotonics (extinction at ca. 900 nm and nanomagnetism (superparamagnetism and provide a potentially useful new nanoarchitecture for biomedical or catalytic applications that can benefit from both activation by light and manipulation using an external magnetic field.

  10. Intracellular Delivery of siRNA by Polycationic Superparamagnetic Nanoparticles

    Directory of Open Access Journals (Sweden)

    Betzaida Castillo

    2012-01-01

    Full Text Available The siRNA transfection efficiency of nanoparticles (NPs, composed of a superparamagnetic iron oxide core modified with polycationic polymers (poly(hexamethylene biguanide or branched polyethyleneimine, were studied in CHO-K1 and HeLa cell lines. Both NPs demonstrated to be good siRNA transfection vehicles, but unmodified branched polyethyleneimine (25 kD was superior on both cell lines. However, application of an external magnetic field during transfection (magnetofection increased the efficiency of the superparamagnetic NPs. Furthermore, our results reveal that these NPs are less toxic towards CHO-K1 cell lines than the unmodified polycationic-branched polyethyleneimine (PEI. In general, the external magnetic field did not alter the cell’s viability nor it disrupted the cell membranes, except for the poly(hexamethylene biguanide-modified NP, where it was observed that in CHO-K1 cells application of the external magnetic field promoted membrane damage. This paper presents new polycationic superparamagnetic NPs as promising transfection vehicles for siRNA and demonstrates the advantages of magnetofection.

  11. Effects of Superparamagnetic Nanoparticle Clusters on the Polymerase Chain Reaction

    Directory of Open Access Journals (Sweden)

    Toshiaki Higashi

    2012-04-01

    Full Text Available The polymerase chain reaction (PCR method is widely used for the reproduction and amplification of specific DNA segments, and a novel PCR method using nanomaterials such as gold nanoparticles has recently been reported. This paper reports on the effects of superparamagnetic nanoparticles on PCR amplification without an external magnetic field, and clarifies the mechanism behind the effects of superparamagnetic particle clusters on PCR efficiency by estimating the structures of such clusters in PCR. It was found that superparamagnetic nanoparticles tend to inhibit PCR amplification depending on the structure of the magnetic nanoparticle clusters. The paper also clarifies that Taq polymerase is captured in the spaces formed among magnetic nanoparticle clusters, and that it is captured more efficiently as a result of their motion from heat treatment in PCR thermal cycles. Consequently, Taq polymerase that should be used in PCR is reduced in the PCR solution. These outcomes will be applied to novel PCR techniques using magnetic particles in an external magnetic field.

  12. Atomic layer deposition of superparamagnetic and ferrimagnetic magnetite thin films

    International Nuclear Information System (INIS)

    Zhang, Yijun; Liu, Ming; Ren, Wei; Zhang, Yuepeng; Chen, Xing; Ye, Zuo-Guang

    2015-01-01

    One of the key challenges in realizing superparamagnetism in magnetic thin films lies in finding a low-energy growth way to create sufficiently small grains and magnetic domains which allow the magnetization to randomly and rapidly reverse. In this work, well-defined superparamagnetic and ferrimagnetic Fe 3 O 4 thin films are successfully prepared using atomic layer deposition technique by finely controlling the growth condition and post-annealing process. As-grown Fe 3 O 4 thin films exhibit a conformal surface and poly-crystalline nature with an average grain size of 7 nm, resulting in a superparamagnetic behavior with a blocking temperature of 210 K. After post-annealing in H 2 /Ar at 400 °C, the as-grown α−Fe 2 O 3 sample is reduced to Fe 3 O 4 phase, exhibiting a ferrimagnetic ordering and distinct magnetic shape anisotropy. Atomic layer deposition of magnetite thin films with well-controlled morphology and magnetic properties provides great opportunities for integrating with other order parameters to realize magnetic nano-devices with potential applications in spintronics, electronics, and bio-applications

  13. Blood Compatibility of Sulfonated Cladophora Nanocellulose Beads

    Directory of Open Access Journals (Sweden)

    Igor Rocha

    2018-03-01

    Full Text Available Sulfonated cellulose beads were prepared by oxidation of Cladophora nanocellulose to 2,3-dialdehyde cellulose followed by sulfonation using bisulfite. The physicochemical properties of the sulfonated beads, i.e., high surface area, high degree of oxidation, spherical shape, and the possibility of tailoring the porosity, make them interesting candidates for the development of immunosorbent platforms, including their application in extracorporeal blood treatments. A desired property for materials used in such applications is blood compatibility; therefore in the present work, we investigate the hemocompatibility of the sulfonated cellulose beads using an in vitro whole blood model. Complement system activation (C3a and sC5b-9 levels, coagulation activation (thrombin-antithrombin (TAT levels and hemolysis were evaluated after whole blood contact with the sulfonated beads and the results were compared with the values obtained with the unmodified Cladophora nanocellulose. Results showed that neither of the cellulosic materials presented hemolytic activity. A marked decrease in TAT levels was observed after blood contact with the sulfonated beads, compared with Cladophora nanocellulose. However, the chemical modification did not promote an improvement in Cladophora nanocellulose hemocompatibility in terms of complement system activation. Even though the sulfonated beads presented a significant reduction in pro-coagulant activity compared with the unmodified material, further modification strategies need to be investigated to control the complement activation by the cellulosic materials.

  14. Blood Compatibility of Sulfonated Cladophora Nanocellulose Beads.

    Science.gov (United States)

    Rocha, Igor; Lindh, Jonas; Hong, Jaan; Strømme, Maria; Mihranyan, Albert; Ferraz, Natalia

    2018-03-07

    Sulfonated cellulose beads were prepared by oxidation of Cladophora nanocellulose to 2,3-dialdehyde cellulose followed by sulfonation using bisulfite. The physicochemical properties of the sulfonated beads, i.e., high surface area, high degree of oxidation, spherical shape, and the possibility of tailoring the porosity, make them interesting candidates for the development of immunosorbent platforms, including their application in extracorporeal blood treatments. A desired property for materials used in such applications is blood compatibility; therefore in the present work, we investigate the hemocompatibility of the sulfonated cellulose beads using an in vitro whole blood model. Complement system activation (C3a and sC5b-9 levels), coagulation activation (thrombin-antithrombin (TAT) levels) and hemolysis were evaluated after whole blood contact with the sulfonated beads and the results were compared with the values obtained with the unmodified Cladophora nanocellulose. Results showed that neither of the cellulosic materials presented hemolytic activity. A marked decrease in TAT levels was observed after blood contact with the sulfonated beads, compared with Cladophora nanocellulose. However, the chemical modification did not promote an improvement in Cladophora nanocellulose hemocompatibility in terms of complement system activation. Even though the sulfonated beads presented a significant reduction in pro-coagulant activity compared with the unmodified material, further modification strategies need to be investigated to control the complement activation by the cellulosic materials.

  15. Improved Peak Capacity for Capillary Electrophoretic Separations of Enzyme Inhibitors with Activity-Based Detection Using Magnetic Bead Microreactors

    Science.gov (United States)

    Yan, Xiaoyan; Gilman, S. Douglass

    2010-01-01

    A technique for separating and detecting enzyme inhibitors was developed using capillary electrophoresis with an enzyme microreactor. The on-column enzyme microreactor was constructed using NdFeB magnet(s) to immobilize alkaline phosphatase-coated superparamagnetic beads (2.8 μm diameter) inside a capillary before the detection window. Enzyme inhibition assays were performed by injecting a plug of inhibitor into a capillary filled with the substrate, AttoPhos. Product generated in the enzyme microreactor was detected by laser-induced fluorescence. Inhibitor zones electrophoresed through the capillary, passed through the enzyme microreactor, and were observed as negative peaks due to decreased product formation. The goal of this study was to improve peak capacities for inhibitor separations relative to previous work, which combined continuous engagement electrophoretically mediated microanalysis (EMMA) and transient engagement EMMA to study enzyme inhibition. The effects of electric field strength, bead injection time and inhibitor concentrations on peak capacity and peak width were investigated. Peak capacities were increased to ≥20 under optimal conditions of electric field strength and bead injection time for inhibition assays with arsenate and theophylline. Five reversible inhibitors of alkaline phosphatase (theophylline, vanadate, arsenate, L-tryptophan and tungstate) were separated and detected to demonstrate the ability of this technique to analyze complex inhibitor mixtures. PMID:20024913

  16. High heat generation ability in AC magnetic field for nano-sized magnetic Y3Fe5O12 powder prepared by bead milling

    International Nuclear Information System (INIS)

    Aono, Hiromichi; Ebara, Hiroki; Senba, Ryota; Naohara, Takashi; Maehara, Tsunehiro; Hirazawa, Hideyuki; Watanabe, Yuji

    2012-01-01

    Nano-sized magnetic Y 3 Fe 5 O 12 ferrite having a high heat generation ability in an AC magnetic field was prepared by bead milling. A commercial powder sample (non-milled sample) of ca. 2.9 μm in particle size did not show any temperature enhancement in the AC magnetic field. The heat generation ability in the AC magnetic field improved with a decrease in the average crystallite size for the bead-milled Y 3 Fe 5 O 12 ferrites. The highest heat ability in the AC magnetic field was for the fine Y 3 Fe 5 O 12 powder with a 15-nm crystallite size (the samples were milled for 4 h using 0.1 mmφ beads). The heat generation ability of the excessively milled Y 3 Fe 5 O 12 samples decreased. The main reason for the high heat generation property of the milled samples was ascribed to an increase in the Néel relaxation of the superparamagnetic material. The heat generation ability was not influenced by the concentration of the ferrite powder. For the samples milled for 4 h using 0.1 mmφ beads, the heat generation ability (W g −1 ) was estimated using a 3.58×10 −4 fH 2 frequency (f/kHz) and the magnetic field (H/kA m −1 ), which is the highest reported value of superparamagnetic materials. - Highlights: ► The nano-sized Y 3 Fe 5 O 12 powder prepared by bead-milling has the highest heat generation ability in an AC magnetic field. ► The heat generation properties are ascribed to an increase in the Néel relaxation of the superparamagnetic material. ► The heat ability (W g −1 ) can be estimated using 3.58×10 −4 fH 2 (f=kHz, H=kA m −1 ). ► This is an expectable material for use in a drug delivery system for the thermal coagulation therapy of cancer tumors.

  17. The Beads of Translation: Using Beads to Translate mRNA into a Polypeptide Bracelet

    Science.gov (United States)

    Dunlap, Dacey; Patrick, Patricia

    2012-01-01

    During this activity, by making beaded bracelets that represent the steps of translation, students simulate the creation of an amino acid chain. They are given an mRNA sequence that they translate into a corresponding polypeptide chain (beads). This activity focuses on the events and sites of translation. The activity provides students with a…

  18. Enhanced pulsed magneto-motive ultrasound imaging using superparamagnetic nanoclusters

    International Nuclear Information System (INIS)

    Mehrmohammadi, M; Qu, M; Emelianov, S Y; Yoon, K Y; Johnston, K P

    2011-01-01

    Recently, pulsed magneto-motive ultrasound (pMMUS) imaging augmented with ultra-small magnetic nanoparticles has been introduced as a tool capable of imaging events at molecular and cellular levels. The sensitivity of a pMMUS system depends on several parameters, including the size, geometry and magnetic properties of the nanoparticles. Under the same magnetic field, larger magnetic nanostructures experience a stronger magnetic force and produce larger displacement, thus improving the sensitivity and signal-to-noise ratio (SNR) of pMMUS imaging. Unfortunately, large magnetic iron-oxide nanoparticles are typically ferromagnetic and thus are very difficult to stabilize against colloidal aggregation. In the current study we demonstrate improvement of pMMUS image quality by using large size superparamagnetic nanoclusters characterized by strong magnetization per particle. Water-soluble magnetic nanoclusters of two sizes (15 and 55 nm average size) were synthesized from 3 nm iron precursors in the presence of citrate capping ligand. The size distribution of synthesized nanoclusters and individual nanoparticles was characterized using dynamic light scattering (DLS) analysis and transmission electron microscopy (TEM). Tissue mimicking phantoms containing single nanoparticles and two sizes of nanoclusters were imaged using a custom-built pMMUS imaging system. While the magnetic properties of citrate-coated nanoclusters are identical to those of superparamagnetic nanoparticles, the magneto-motive signal detected from nanoclusters is larger, i.e. the same magnetic field produced larger magnetically induced displacement. Therefore, our study demonstrates that clusters of superparamagnetic nanoparticles result in pMMUS images with higher contrast and SNR.

  19. In situ hybridization of superparamagnetic iron-biomolecule nanoparticles.

    Science.gov (United States)

    Moghimi, Nafiseh; Donkor, Apraku David; Mohapatra, Mamata; Thomas, Joseph Palathinkal; Su, Zhengding; Tang, Xiaowu Shirley; Leung, Kam Tong

    2014-07-23

    The increase in interest in the integration of organic-inorganic nanostructures in recent years has promoted the use of hybrid nanoparticles (HNPs) in medicine, energy conversion, and other applications. Conventional hybridization methods are, however, often long, complicated, and multistepped, and they involve biomolecules and discrete nanostructures as separate entities, all of which hinder the practical use of the resulting HNPs. Here, we present a novel, in situ approach to synthesizing size-specific HNPs using Fe-biomolecule complexes as the building blocks. We choose an anticancer peptide (p53p, MW 1.8 kDa) and an enzyme (GOx, MW 160 kDa) as model molecules to demonstrate the versatility of the method toward different types of molecules over a large size range. We show that electrostatic interaction for complex formation of metal hydroxide ion with the partially charged side of biomolecule in the solution is the key to hybridization of metal-biomolecule materials. Electrochemical deposition is then used to produce hybrid NPs from these complexes. These HNPs with controllable sizes ranging from 30 nm to 3.5 μm are found to exhibit superparamagnetic behavior, which is a big challenge for particles in this size regime. As an example of greatly improved properties and functionality of the new hybrid material, in vitro toxicity assessment of Fe-GOx HNPs shows no adverse effect, and the Fe-p53p HNPs are found to selectively bind to cancer cells. The superparamagnetic nature of these HNPs (superparamagnetic even above the size regime of 15-20 nm!), their biocompatibility, and the direct integration approach are fundamentally important to biomineralization and general synthesis strategy for bioinspired functional materials.

  20. Fluxgate magnetorelaxometry of superparamagnetic nanoparticles for hydrogel characterization

    International Nuclear Information System (INIS)

    Heim, Erik; Harling, Steffen; Poehlig, Kai; Ludwig, Frank; Menzel, Henning; Schilling, Meinhard

    2007-01-01

    A new characterization method for hydrogels based on the relaxation behavior of superparamagnetic nanoparticles (MNPs) is proposed. MNPs are incorporated in the hydrogel to examine its network properties. By analyzing their relaxation behavior, incorporated and mobile nanoparticles can be studied. In the case of mobile nanoparticles, the microviscosity of the hydrogel can be determined. Thus, this method allows the studying of gelation as well as the degradation process of hydrogels. Furthermore, the hydrogel can have any shape (e.g. microspheres or larger blocks) and no sample preparation is needed, avoiding artefacts

  1. Superparamagnetic perpendicular magnetic tunnel junctions for true random number generators

    Science.gov (United States)

    Parks, Bradley; Bapna, Mukund; Igbokwe, Julianne; Almasi, Hamid; Wang, Weigang; Majetich, Sara A.

    2018-05-01

    Superparamagnetic perpendicular magnetic tunnel junctions are fabricated and analyzed for use in random number generators. Time-resolved resistance measurements are used as streams of bits in statistical tests for randomness. Voltage control of the thermal stability enables tuning the average speed of random bit generation up to 70 kHz in a 60 nm diameter device. In its most efficient operating mode, the device generates random bits at an energy cost of 600 fJ/bit. A narrow range of magnetic field tunes the probability of a given state from 0 to 1, offering a means of probabilistic computing.

  2. ADSORPTION AND RELEASING PROPERTIES OF BEAD CELLULOSE

    Institute of Scientific and Technical Information of China (English)

    A. Morales; E. Bordallo; V. Leon; J. Rieumont

    2004-01-01

    The adsorption of some dyes on samples of bead cellulose obtained in the Unit of Research-Production "Cuba 9"was studied. Methylene blue, alizarin red and congo red fitted the adsorption isotherm of Langmuir. Adsorption kinetics at pH = 6 was linear with the square root of time indicating the diffusion is the controlling step. At pH = 12 a non-Fickian trend was observed and adsorption was higher for the first two dyes. Experiments carried out to release the methylene blue occluded in the cellulose beads gave a kinetic behavior of zero order. The study of cytochrome C adsorption was included to test a proteinic material. Crosslinking of bead cellulose was performed with epichlorohydrin decreasing its adsorption capacity in acidic or alkaline solution.

  3. Bead Capture on Magnetic Sensors in a Microfluidic System

    DEFF Research Database (Denmark)

    Østerberg, Frederik Westergaard; Dalslet, Bjarke Thomas; Damsgaard, Christian Danvad

    2009-01-01

    The accumulation of magnetic beads by gravitational sedimentation and magnetic capture on a planar Hall-effect sensor integrated in a microfluidic channel is studied systematically as a function of the bead concentration, the fluid flow rate, and the sensor bias current. It is demonstrated...... that the sedimentation flux is proportional to the bead concentration and has a power law relation to the fluid flow rate. The mechanisms for the bead accumulation are investigated and it is found that gravitational sedimentation dominates the bead accumulation, whereas the stability of the sedimented beads against...

  4. Cooling Rates of Lunar Volcanic Glass Beads

    Science.gov (United States)

    Hui, Hejiu; Hess, Kai-Uwe; Zhang, Youxue; Peslier, Anne; Lange, Rebecca; Dingwell, Donald; Neal, Clive

    2016-01-01

    It is widely accepted that the Apollo 15 green and Apollo 17 orange glass beads are of volcanic origin. The diffusion profiles of volatiles in these glass beads are believed to be due to degassing during eruption (Saal et al., 2008). The degree of degassing depends on the initial temperature and cooling rate. Therefore, the estimations of volatiles in parental magmas of lunar pyroclastic deposits depend on melt cooling rates. Furthermore, lunar glass beads may have cooled in volcanic environments on the moon. Therefore, the cooling rates may be used to assess the atmospheric condition in an early moon, when volcanic activities were common. The cooling rates of glasses can be inferred from direct heat capacity measurements on the glasses themselves (Wilding et al., 1995, 1996a,b). This method does not require knowledge of glass cooling environments and has been applied to calculate the cooling rates of natural silicate glasses formed in different terrestrial environments. We have carried out heat capacity measurements on hand-picked lunar glass beads using a Netzsch DSC 404C Pegasus differential scanning calorimeter at University of Munich. Our preliminary results suggest that the cooling rate of Apollo 17 orange glass beads may be 12 K/min, based on the correlation between temperature of the heat capacity curve peak in the glass transition range and glass cooling rate. The results imply that the parental magmas of lunar pyroclastic deposits may have contained more water initially than the early estimations (Saal et al., 2008), which used higher cooling rates, 60-180 K/min in the modeling. Furthermore, lunar volcanic glass beads could have been cooled in a hot gaseous medium released from volcanic eruptions, not during free flight. Therefore, our results may shed light on atmospheric condition in an early moon.

  5. Beads from Inhumation Rite Burials of Gnezdovo Burial Mound

    Directory of Open Access Journals (Sweden)

    Dobrova Olga P.

    2017-12-01

    Full Text Available The beads from 33 inhumation burials at Gnezdovo burial mound are examined in the article. The beads (total 367 were crafted from stretched tube (258, stretched stick (3, winding (45, press molding (2 pcs., welding (2 pcs., and mosaic beads (9 pcs.. The burial mound contains virtually no broken beads, including the settlement's most common yellow glass beads. Besides glass beads, cornelian, crystal, amber and faience beads have been registered among the burial mound material, as well as beads crafted with metal. Apart from beads, grave inventories contained a series of pendants with a bead strung on a wire ring. The considered complexes contain five pendants of this type. Besides Gnezdovo, similar pendants have been discovered in Kiev, Timerev, Pskov and Vladimir barrows. A comparison between bead sets from Gnezdovo and Kiev burial mounds allows to conclude that the general composition and occurrence frequency of beads is identical for these burials. At the same time, beads crafted with rock crystal, cornelian and metal are more frequently discovered in Kiev inhumations.

  6. Synthesis of superparamagnetic nanoparticles dispersed in spherically shaped carbon nanoballs

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, E.M.M., E-mail: e.ibrahim@science.sohag.edu.eg; Hampel, Silke; Thomas, Juergen; Haase, Diana; Wolter, A. U. B.; Khavrus, Vyacheslav O.; Taeschner, Christine; Leonhardt, Albrecht; Buechner, Bernd [Leibniz Institute of Solid State and Material Research (Germany)

    2012-09-15

    In this work, carbon nanoballs in spherical shape with diameter 70 {+-} 2 nm containing well-dispersed superparamagnetic magnetite/maghemite Fe{sub 3}O{sub 4}/{gamma}-Fe{sub 2}O{sub 3} nanoparticles of 5-10 nm in size were synthesised by a facile route using the radio frequency (rf) plasma in order to assist the pyrolysis of ferrocene. Ferrocene was placed in an inductively coupled rf plasma field without additional thermal heating to activate simultaneous sublimation and pre-pyrolysis processes. During this plasma activation, the resultant derivatives were carried by an argon gas stream into the hot zone of a resistance furnace (600 Degree-Sign C) for complete thermal decomposition. The deposition of the nanoballs could be observed in the hot zone of the furnace at a temperature of 600 Degree-Sign C. The synthesised nanoballs are highly dispersible in solvents that make them particularly suitable for different applications. Their morphology, composition and structure were characterized by high-resolution scanning and transmission electron microscopy, including selected area electron diffraction, electron energy loss spectroscopy and X-ray diffraction. Magnetic measurements demonstrated that the nanoballs possess superparamagnetic characteristics.

  7. Synthesis and super-paramagnetic properties of neodymium ferrites nanorods

    Energy Technology Data Exchange (ETDEWEB)

    El moussaoui, H. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Laboratoire of Magnetism and the Physics of the High Energies, URAC 12, Departement of Physique, Faculty of Science, Mohammed V- Agdal University, BP 1014, Rabat (Morocco); Mounkachi, O., E-mail: o.mounkachi@mascir.com [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Masrour, R. [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, Route Sidi Bouzid, BP 63, 46000 Safi (Morocco); Hamedoun, M., E-mail: hamedoun@hotmail.com [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Hlil, E.K. [Institut Néel, CNRS-UJF, B.P. 166, 38042 Grenoble Cedex (France); Benyoussef, A. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Laboratoire of Magnetism and the Physics of the High Energies, URAC 12, Departement of Physique, Faculty of Science, Mohammed V- Agdal University, BP 1014, Rabat (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco)

    2013-12-25

    Highlights: •Magnetic properties of Neodymium nanorods depend on calcination temperature. •The as-synthesized Nd ferrite nanorods are superparamagnetic at room temperature. •The blocking temperature is higher than room temperature. -- Abstract: In this work we report the microstructural characterization and the magnetic properties of neodymium ferrites (NdFe{sub 2}O{sub 4}) nanorods prepared by well controlled co-precipitation method. The effect of annealing temperature on the structure, morphology and magnetic properties of NdFe{sub 2}O{sub 4} has been investigated. The transmission electron microscopy (TEM) observations revealed that the as-prepared nanoparticles have rods-like shape with the average diameter ranging from 5 to 14 nm and uniform length. The magnetic measurements show that the as-synthesized nanorods have a superparamagnetic behavior at room temperature, with a blocking temperature of 360 K and magnetic anisotropy constant of 2.8 × 10{sup 5} ergs/cm{sup 3}. The magnetization and coercitivity at room temperature are increased from 26 to 34 emu/g and from 151 to 171 Oe with increasing annealing temperature from 400 to 600 °C, respectively.

  8. Highly fluorescent and superparamagnetic nanosystem for biomedical applications

    Science.gov (United States)

    Cabrera, Mariana P.; E Cabral Filho, Paulo; Silva, Camila M. C. M.; Oliveira, Rita M.; Geraldes, Carlos F. G. C.; Castro, M. Margarida C. A.; Costa, Benilde F. O.; Henriques, Marta S. C.; Paixão, José A.; Carvalho, Luiz B., Jr.; Santos, Beate S.; Hallwass, Fernando; Fontes, Adriana; Pereira, Giovannia A. L.

    2017-07-01

    This work reports on highly fluorescent and superparamagnetic bimodal nanoparticles (BNPs) obtained by a simple and efficient method as probes for fluorescence analysis and/or contrast agents for MRI. These promising BNPs with small dimensions (ca. 17 nm) consist of superparamagnetic iron oxide nanoparticles (SPIONs) covalently bound with CdTe quantum dots (ca. 3 nm). The chemical structure of the magnetic part of BNPs is predominantly magnetite, with minor goethite and maghemite contributions, as shown by Mössbauer spectroscopy, which is compatible with the x-ray diffraction data. Their size evaluation by different techniques showed that the SPION derivatization process, in order to produce the BNPs, does not lead to a large size increase. The BNPs saturation magnetization, when corrected for the organic content of the sample, is ca. 68 emu g-1, which is only slightly reduced relative to the bare nanoparticles. This indicates that the SPION surface functionalization does not change considerably the magnetic properties. The BNP aqueous suspensions presented stability, high fluorescence, high relaxivity ratio (r 2/r 1 equal to 25) and labeled efficiently HeLa cells as can be seen by fluorescence analysis. These BNP properties point to their applications as fluorescent probes as well as negative T 2-weighted MRI contrast agents. Moreover, their potential magnetic response could also be used for fast bioseparation applications.

  9. exploring traditional glass bead making techniques in jewellery

    African Journals Online (AJOL)

    User

    Glass bead making techniques and their mass production will help the individual ... communicate cultural values in a symbolic lan- guage which ..... Surface of most of the new beads were rough ... tourism potential to be developed further to.

  10. Fungal cultivation on glass-beads

    DEFF Research Database (Denmark)

    Droce, Aida; Sørensen, Jens Laurids; Giese, Henriette

    Transcription of various bioactive compounds and enzymes are dependent on fungal cultivation method. In this study we cultivate Fusarium graminearum and Fusarium solani on glass-beads with liquid media in petri dishes as an easy and inexpensive cultivation method, that resembles in secondary...... metabolite production to agar-cultivation but with an easier and more pure RNA-extraction of total fungal mycelia....

  11. Study on the etched carnelian beads unearthed in China

    Institute of Scientific and Technical Information of China (English)

    Deyun Zhao

    2014-01-01

    Etched carnelian beads originated in the Indus Civilization;this kind of ornaments and its manufacturing techniques were spread to the whole Eurasia Continent.The etched carnelian beads unearthed in China can be classified into four types,the comparisons of which to their foreign counterparts may reveal their different sources and diffusion routes.The etched carnelian beads and their glass imitations unearthed in China had influences to the making of the glass "eye beads" in

  12. Metal-Containing Polystyrene Beads as Standards for Mass Cytometry.

    Science.gov (United States)

    Abdelrahman, Ahmed I; Ornatsky, Olga; Bandura, Dmitry; Baranov, Vladimir; Kinach, Robert; Dai, Sheng; Thickett, Stuart C; Tanner, Scott; Winnik, Mitchell A

    2010-01-01

    We examine the suitability of metal-containing polystyrene beads for the calibration of a mass cytometer instrument, a single particle analyser based on an inductively coupled plasma ion source and a time of flight mass spectrometer. These metal-containing beads are also verified for their use as internal standards for this instrument. These beads were synthesized by multiple-stage dispersion polymerization with acrylic acid as a comonomer. Acrylic acid acts as a ligand to anchor the metal ions within the interior of the beads. Mass cytometry enabled the bead-by-bead measurement of the metal-content and determination of the metal-content distribution. Beads synthesized by dispersion polymerization that involved three stages were shown to have narrower bead-to-bead variation in their lanthanide content than beads synthesized by 2-stage dispersion polymerization. The beads exhibited insignificant release of their lanthanide content to aqueous solutions of different pHs over a period of six months. When mixed with KG1a or U937 cell lines, metal-containing polymer beads were shown not to affect the mass cytometry response to the metal content of element-tagged antibodies specifically attached to these cells.

  13. A Controlled Drug-Delivery Experiment Using Alginate Beads

    Science.gov (United States)

    Farrell, Stephanie; Vernengo, Jennifer

    2012-01-01

    This paper describes a simple, cost-effective experiment which introduces students to drug delivery and modeling using alginate beads. Students produce calcium alginate beads loaded with drug and measure the rate of release from the beads for systems having different stir rates, geometries, extents of cross-linking, and drug molecular weight.…

  14. Assessment of the Problems of Manual Automobile Tyre Bead ...

    African Journals Online (AJOL)

    The tyre-rim bead bond must be broken to carry out repairs on a failed automobile tyre. The use of the locally fabricated manual bead breaking equipment as it is being practiced today by commercial tyre repair artisans in Nigeria is characterized by drudgery. This article reports a study of the local manual bead breaking ...

  15. New Nanoparticles Dispersing Beads Mill with Ultra Small Beads and its Application

    International Nuclear Information System (INIS)

    Inkyo, M; Tahara, T; Imajyo, Y

    2011-01-01

    Two of the major problems related to nanoparticle dispersion with a conventional beads mill are re-agglomeration and damage to the crystalline structure of the particles. The Ultra Apex Mill was developed to solve these problems by enabling the use of ultra-small beads with a diameter of less than 0.1mm. The core of this breakthrough development is centrifugation technology which allows the use of beads as small as 0.015mm. When dispersing agglomerated nanoparticles the impulse of the small beads is very low which means there is little influence on the particles. The surface energy of the nanoparticles remains low so the properties are not likely to change. As a result, stable nanoparticle dispersions can be achieved without re-cohesion. The Ultra Apex Mill is superior to conventional beads mills that are limited to much larger bead sizes. The technology of the Ultra Apex Mill has pioneered practical applications for nanoparticles in various fields: composition materials for LCD screens, ink-jet printing, ceramic condensers and cosmetics.

  16. Friction of N-bead macromolecules in solution: Effects of the bead-solvent interaction

    International Nuclear Information System (INIS)

    Uvarov, Alexander; Fritzsche, Stephan

    2006-01-01

    The role of the bead-solvent interaction has been studied for its influence on the dynamics of an N-bead macromolecule which is immersed into a solution. Using a Fokker-Planck equation for the phase-space distribution function of the macromolecule, we show that all the effects of the solution can be treated entirely in terms of the friction tensors which are assigned to each pair of interacting beads in the chain. For the high-density as well as for the critical solvent, the properties of these tensors are discussed in detail and are calculated by using several (realistic) choices of the bead-solvent potential. From the friction tensors, moreover, an expression for the center-of-mass friction coefficient of a (N-bead) chain macromolecule is derived. Numerical data for this coefficient for 'truncated' Lennard-Jones bead-solvent potential are compared with results from molecular dynamic simulations and from the phenomenological theoretical data as found in the literature

  17. Experimental study of the biological properties of 188Re-Hepama-1 biologic superparamagnetic nanoparticles

    International Nuclear Information System (INIS)

    Feng Yanlin; Tan Jiaju; Sun Jing; Wen Guanghua; Wu Xiaolian; Liang Sheng; Xia Jiaoyun

    2007-01-01

    Objective: To investigate a new biologic-superparamagnetic nanoparticles's characteristics of immunological activity, biological distributing in vivo, targeting and inhibiting tumor effect. Methods: The experimental group 188 Re-Hepama-l-superparamagnetic nanoparticles, and control groups, including 188 ReO 4 - , 188 Re-Hepama-1, and 188 Re-superparamagnetic nanoparticles, were set up. The distributions were measured after injection 4 h and 24 h by caudal vein of Kuming mice. The magnetic targeting experiments in vivo were clone with and without magnetic field in liver after injection in New Zealand rabbit. The inhibiting tumor effect on hepatic cancer cell lines SMMC-7721 of the above four 188 Re labeled products were measured by mono nuclear cell direct cytotoxicity assay method. Results: After injection 4 h and 24 h by vein, the liver taking was highest in group 188 Re-Hepama-l-superparamagnetic nanoparticles. The radiative activity in liver in magnetism zoo was higher than in non magnetism zoo in 188 Re- Hepama-1-superparamagnetic nanoparticles after applying magnetic field in left lobe of liver, and the ratio of in magnetism zoo to non magnetism zoo was 1.87. And the half effective inhibition radioactive concentrations (IC 50 ) in 188 Re-Hepama-l-superparamagnetic nanoparticles was one forth of 188 ReO 4 - . Conclusion: 188 Re- Hepama-l-superparamagnetic nanoparticles showed its fine stability in intro, good immunological activity and significant liver target. (authors)

  18. Bead-bead interaction parameters in dissipative particle dynamics: Relation to bead-size, solubility parameter, and surface tension

    Science.gov (United States)

    Maiti, Amitesh; McGrother, Simon

    2004-01-01

    Dissipative particle dynamics (DPD) is a mesoscale modeling method for simulating equilibrium and dynamical properties of polymers in solution. The basic idea has been around for several decades in the form of bead-spring models. A few years ago, Groot and Warren [J. Chem. Phys. 107, 4423 (1997)] established an important link between DPD and the Flory-Huggins χ-parameter theory for polymer solutions. We revisit the Groot-Warren theory and investigate the DPD interaction parameters as a function of bead size. In particular, we show a consistent scheme of computing the interfacial tension in a segregated binary mixture. Results for three systems chosen for illustration are in excellent agreement with experimental results. This opens the door for determining DPD interactions using interfacial tension as a fitting parameter.

  19. Activity of an enzyme immobilized on superparamagnetic particles in a rotational magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Mizuki, Toru; Watanabe, Noriyuki; Nagaoka, Yutaka [Bio-Nano Electronics Research Centre, Toyo University, Saitama 350-8585 (Japan); Fukushima, Tadamasa [Shimadzu GLC Ltd., Phenomenex Support Centre, Tokyo 110-0016 (Japan); Morimoto, Hisao; Usami, Ron [Bio-Nano Electronics Research Centre, Toyo University, Saitama 350-8585 (Japan); Maekawa, Toru, E-mail: maekawa@toyonet.toyo.ac.jp [Bio-Nano Electronics Research Centre, Toyo University, Saitama 350-8585 (Japan)

    2010-03-19

    We immobilize {alpha}-amylase extracted from Bacillus Iicheniformis on the surfaces of superparamagnetic particles and investigate the effect of a rotational magnetic field on the enzyme's activity. We find that the activity of the enzyme molecules immobilized on superparamagnetic particles increases in the rotational magnetic field and reaches maximum at a certain frequency. We clarify the effect of the cluster structures formed by the superparamagnetic particles on the activity. Enzyme reactions are enhanced even in a tiny volume of solution using the present method, which is very important for the development of efficient micro reactors and micro total analysis systems ({mu}-TAS).

  20. Genotoxicity of Superparamagnetic Iron Oxide Nanoparticles in Granulosa Cells

    Directory of Open Access Journals (Sweden)

    Marina Pöttler

    2015-11-01

    Full Text Available Nanoparticles that are aimed at targeting cancer cells, but sparing healthy tissue provide an attractive platform of implementation for hyperthermia or as carriers of chemotherapeutics. According to the literature, diverse effects of nanoparticles relating to mammalian reproductive tissue are described. To address the impact of nanoparticles on cyto- and genotoxicity concerning the reproductive system, we examined the effect of superparamagnetic iron oxide nanoparticles (SPIONs on granulosa cells, which are very important for ovarian function and female fertility. Human granulosa cells (HLG-5 were treated with SPIONs, either coated with lauric acid (SEONLA only, or additionally with a protein corona of bovine serum albumin (BSA; SEONLA-BSA, or with dextran (SEONDEX. Both micronuclei testing and the detection of γH2A.X revealed no genotoxic effects of SEONLA-BSA, SEONDEX or SEONLA. Thus, it was demonstrated that different coatings of SPIONs improve biocompatibility, especially in terms of genotoxicity towards cells of the reproductive system.

  1. Potential toxicity of superparamagnetic iron oxide nanoparticles (SPION

    Directory of Open Access Journals (Sweden)

    Neenu Singh

    2010-09-01

    Full Text Available Superparamagnetic iron oxide nanoparticles (SPION are being widely used for various biomedical applications, for example, magnetic resonance imaging, targeted delivery of drugs or genes, and in hyperthermia. Although, the potential benefits of SPION are considerable, there is a distinct need to identify any potential cellular damage associated with these nanoparticles. Besides focussing on cytotoxicity, the most commonly used determinant of toxicity as a result of exposure to SPION, this review also mentions the importance of studying the subtle cellular alterations in the form of DNA damage and oxidative stress. We review current studies and discuss how SPION, with or without different surface coating, may cause cellular perturbations including modulation of actin cytoskeleton, alteration in gene expression profiles, disturbance in iron homeostasis and altered cellular responses such as activation of signalling pathways and impairment of cell cycle regulation. The importance of protein–SPION interaction and various safety considerations relating to SPION exposure are also addressed.

  2. Superparamagnetic bimetallic iron-palladium nanoalloy: synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Nazir, Rabia; Mazhar, Muhammad [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Akhtar, M Javed; Nadeem, M; Siddique, Muhammad [Physics Division, PINSTECH, PO Nilore, Islamabad 44000 (Pakistan); Shah, M Raza [HEJ Research Institute of Chemistry, University of Karachi, Karachi 75270 (Pakistan); Khan, Nawazish A [Material Science Laboratory, Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Mehmood, Mazhar [National Centre for Nanotechnology, PIEAS, Islamabad 45650 (Pakistan); Butt, N M [Pakistan Science Foundation, Islamabad 44000 (Pakistan)], E-mail: mazhar42pk@yahoo.com

    2008-05-07

    Iron-palladium nanoalloy in the particle size range of 15-30 nm is synthesized by the relatively low temperature thermal decomposition of coprecipitated [Fe(Bipy){sub 3}]Cl{sub 2} and [Pd(Bipy){sub 3}]Cl{sub 2} in an inert ambient of dry argon gas. The silvery black Fe-Pd alloy nanoparticles are air-stable and have been characterized by EDX-RF, XRD, AFM, TEM, magnetometry, {sup 57}Fe Moessbauer and impedance spectroscopy. This Fe-Pd nanoalloy is in single phase and contains iron sites having up to 11 nearest-neighboring atoms. It is superparamagnetic in nature with high magnetic susceptibility, low coercivity and hyperfine field.

  3. Multifunctional superparamagnetic nanoparticles for enhanced drug transport in cystic fibrosis

    Science.gov (United States)

    Armijo, Leisha M.; Brandt, Yekaterina I.; Rivera, Antonio C.; Cook, Nathaniel C.; Plumley, John B.; Withers, Nathan J.; Kopciuch, Michael; Smolyakov, Gennady A.; Huber, Dale L.; Smyth, Hugh D.; Osinski, Marek

    2012-10-01

    Iron oxide colloidal nanoparticles (ferrofluids) are investigated for application in the treatment of cystic fibrosis lung infections, the leading cause of mortality in cystic fibrosis patients. We investigate the use of iron oxide nanoparticles to increase the effectiveness of administering antibiotics through aerosol inhalation using two mechanisms: directed particle movement in the presence of an inhomogeneous static external magnetic field and magnetic hyperthermia. Magnetic hyperthermia is an effective method for decreasing the viscosity of the mucus and biofilm, thereby enhancing drug, immune cell, and antibody penetration to the affected area. Iron oxide nanoparticles of various sizes and morphologies were synthesized and tested for specific losses (heating power). Nanoparticles in the superparamagnetic to ferromagnetic size range exhibited excellent heating power. Additionally, iron oxide / zinc selenide core/shell nanoparticles were prepared, in order to enable imaging of the iron oxide nanoparticles. We also report on synthesis and characterization of MnSe/ZnSeS alloyed quantum dots.

  4. Relaxometry imaging of superparamagnetic magnetite nanoparticles at ambient conditions

    Science.gov (United States)

    Finkler, Amit; Schmid-Lorch, Dominik; Häberle, Thomas; Reinhard, Friedemann; Zappe, Andrea; Slota, Michael; Bogani, Lapo; Wrachtrup, Jörg

    We present a novel technique to image superparamagnetic iron oxide nanoparticles via their fluctuating magnetic fields. The detection is based on the nitrogen-vacancy (NV) color center in diamond, which allows optically detected magnetic resonance (ODMR) measurements on its electron spin structure. In combination with an atomic-force-microscope, this atomic-sized color center maps ambient magnetic fields in a wide frequency range from DC up to several GHz, while retaining a high spatial resolution in the sub-nanometer range. We demonstrate imaging of single 10 nm sized magnetite nanoparticles using this spin noise detection technique. By fitting simulations (Ornstein-Uhlenbeck process) to the data, we are able to infer additional information on such a particle and its dynamics, like the attempt frequency and the anisotropy constant. This is of high interest to the proposed application of magnetite nanoparticles as an alternative MRI contrast agent or to the field of particle-aided tumor hyperthermia.

  5. Superparamagnetic nanoparticle-inclusion microbubbles for ultrasound contrast agents

    International Nuclear Information System (INIS)

    Yang Fang; Li Yixin; Chen Zhongping; Gu Ning; Li Ling; Wu Junru

    2008-01-01

    We have developed a new type of ultrasound (US) contrast agent, consisting of a gas core, a layer of superparamagnetic iron oxide Fe 3 O 4 nanoparticles (SPIO) and an oil in water outermost layer. The newly developed US contrast agent microbubbles have a mean diameter of 760 nm with a polydisperity index (PI) of 0.699. Our in vitro and in vivo experiments have shown that they have the following advantages compared to gas-encapsulated microbbubbles without SPIO inclusion: (1) they provide better contrast for US images; (2) the SPIO-inclusion microbubbles generate a higher backscattering signal; the mean grey scale is 97.9, which is 38.6 higher than that of microbubbles without SPIO; and (3) since SPIO can also serve as a contrast agent of magnetic resonance images (MRI) in vitro, they can be potentially used as contrast agents for double-modality (MRI and US) clinical studies.

  6. Deviation from the superparamagnetic behaviour of fine-particle systems

    CERN Document Server

    Malaescu, I

    2000-01-01

    Studies concerning superparamagnetic behaviour of fine magnetic particle systems were performed using static and radiofrequency measurements, in the range 1-60 MHz. The samples were: a ferrofluid with magnetite particles dispersed in kerosene (sample A), magnetite powder (sample B) and the same magnetite powder dispersed in a polymer (sample C). Radiofrequency measurements indicated a maximum in the imaginary part of the complex magnetic susceptibility, for each of the samples, at frequencies with the magnitude order of tens of MHz, the origin of which was assigned to Neel-type relaxation processes. The static measurements showed a Langevin-type dependence of magnetisation M and of susceptibility chi, on the magnetic field for sample A. For samples B and C deviations from this type of dependence were found. These deviations were analysed qualitatively and explained in terms of the interparticle interactions, dispersion medium influence and surface effects.

  7. Superparamagnetic iron oxide nanoparticles (SPIONs) for targeted drug delivery

    Science.gov (United States)

    Garg, Vijayendra K.; Kuzmann, Erno; Sharma, Virender K.; Kumar, Arun; Oliveira, Aderbal C.

    2016-10-01

    Studies of superparamagnetic iron oxide nanoparticles (SPIONs) have been extensively carried out. Since the earlier work on Mössbauer studies on SPIONs in 1970s, many biomedical applications and their uses in innovative methods to produce new materials with improved performance have appeared. Applications of SPIONs in environmental remediation are also forthcoming. Several different methods of synthesis and coating of the magnetic particles have been described in the literature, and Mössbauer spectroscopy has been an important tool in the characterization of these materials. It is quite possible that the interpretation of the Mössbauer spectra might not be entirely correct because the possible presence of maghemite in the end product of SPIONs might not have been taken into consideration. Nanotechnology is an emerging field that covers a wide range of new technologies under development in nanoscale (1 to 100 nano meters) to produce new products and methodology.

  8. Magnetic characterization of superparamagnetic nanoparticles pulled through model membranes.

    Science.gov (United States)

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

    2007-01-04

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

  9. Synthesis and magnetic properties of superparamagnetic CoAs nanostructures

    Science.gov (United States)

    Desai, P.; Ashokaan, N.; Masud, J.; Pariti, A.; Nath, M.

    2015-03-01

    This article provides a comprehensive guide on the synthesis and characterization of superparamagnetic CoAs nanoparticles and elongated nanostructures with high blocking temperature, (TB), via hot-injection precipitation and solvothermal methods. Cobalt arsenides constitute an important family of magnetically active solids that find a variety of applications ranging from magnetic semiconductors to biomedical imaging. While the higher temperature hot-injection precipitation technique (300 °C) yields pure CoAs nanostructures, the lower temperature solvothermal method (200 °C) yields a mixture of CoAs nanoparticles along with other Co-based impurity phases. The synthesis in all these cases involved usage of triphenylarsine ((C6H5)3As) as the As precursor which reacts with solid Co2(CO)8 by ligand displacement to yield a single source precursor. The surfactant, hexadecylamine (HDA) further assists in controlling the morphology of the nanostructures. HDA also provides a basic medium and molten flux-like conditions for the redox chemistry to occur between Co and As at elevated temperatures. The influence of the length of reaction time was investigated by studying the evolution of product morphology over time. It was observed that while spontaneous nucleation at higher temperature followed by controlled growth led to the predominant formation of short nanorods, with longer reaction time, the nanorods were further converted to nanoparticles. The size of the nanoparticles obtained, was mostly in the range of 10-15 nm. The key finding of this work is exceptionally high coercivity in CoAs nanostructures for the first time. Coercivity observed was as high as 0.1 T (1000 Oe) at 2 K. These kinds of magnetic nanostructures find multiple applications in spintronics, whereas the superparamagnetic nanoparticles are viable for use in magnetic storage, ferrofluids and as contrast enhancing agents in MRI.

  10. The control of beads diameter of bead-on-string electrospun nanofibers and the corresponding release behaviors of embedded drugs

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tingxiao [Key Laboratory of Textile Science and Technology (Donghua University), Ministry of Education of China, Shanghai 201620 (China); College of Textiles, Donghua University, Shanghai 201620 (China); Ding, Xin, E-mail: xding@dhu.edu.cn [Key Laboratory of Textile Science and Technology (Donghua University), Ministry of Education of China, Shanghai 201620 (China); College of Textiles, Donghua University, Shanghai 201620 (China); Tian, Lingling, E-mail: lingling_tian@nus.edu.sg [Center of Nanofibers & Nanotechnology, Department of Mechanical Engineering, National University of Singapore, 117576 (Singapore); Hu, Jiyong; Yang, Xudong [Key Laboratory of Textile Science and Technology (Donghua University), Ministry of Education of China, Shanghai 201620 (China); College of Textiles, Donghua University, Shanghai 201620 (China); Ramakrishna, Seeram [Center of Nanofibers & Nanotechnology, Department of Mechanical Engineering, National University of Singapore, 117576 (Singapore); Guangdong-Hongkong-Macau Institute of CNS Regeneration (GHMICR), Jinan University, Guangzhou 510632 (China)

    2017-05-01

    Bead-on-string nanofibers, with appropriate control of the beads diameter, are potential fibrous structures for efficient encapsulation of particle drugs in micron scales and could achieve controlled drug release for tissue engineering applications. In this study, the beads diameter of electrospun bead-on-string nanofibers was controlled by adjusting the concentration of spinning polymer, poly (lactic-co-glycolic acid) (PLGA), and the solvent ratio of chloroform to acetone. The images of the scanning electron microscopy (SEM) suggested that bead-on-string nanofibers could be successfully obtained only with a certain range of PLGA solution concentration. Moreover, with the decrease in the solvent ratio of chloroform to acetone, the range was left-shifted towards a smaller concentration. In addition, increase in the PLGA solution concentration within the range the beads diameter became greater and the shape of the beads changed from oval to slender when increasing the PLGA concentration within the range. The bead-on-string nanofibers with different beads diameter were further used to load micro-particle drugs of tetracycline hydrochloride, as a model drug, to examine the release behavior of nanofibers scaffold. The release profiles of drug loaded bead-on-string nanofibers demonstrated the possibility to alleviate the burst drug release by means of beads diameter control. - Highlights: • Bead diameter of bead-on-string electrospun nanofibers was controlled by varying solvent ratio and polymer concentration. • The effect of the addition of particle drugs on BD of bead-on-string electrospun nanofibers was studied. • The corresponding release behaviors of nanofibers with different BD loading micro-particle drugs were investigated. • Bead-on-string nanofibers with bigger BD could alleviate the initial burst release.

  11. The control of beads diameter of bead-on-string electrospun nanofibers and the corresponding release behaviors of embedded drugs

    International Nuclear Information System (INIS)

    Li, Tingxiao; Ding, Xin; Tian, Lingling; Hu, Jiyong; Yang, Xudong; Ramakrishna, Seeram

    2017-01-01

    Bead-on-string nanofibers, with appropriate control of the beads diameter, are potential fibrous structures for efficient encapsulation of particle drugs in micron scales and could achieve controlled drug release for tissue engineering applications. In this study, the beads diameter of electrospun bead-on-string nanofibers was controlled by adjusting the concentration of spinning polymer, poly (lactic-co-glycolic acid) (PLGA), and the solvent ratio of chloroform to acetone. The images of the scanning electron microscopy (SEM) suggested that bead-on-string nanofibers could be successfully obtained only with a certain range of PLGA solution concentration. Moreover, with the decrease in the solvent ratio of chloroform to acetone, the range was left-shifted towards a smaller concentration. In addition, increase in the PLGA solution concentration within the range the beads diameter became greater and the shape of the beads changed from oval to slender when increasing the PLGA concentration within the range. The bead-on-string nanofibers with different beads diameter were further used to load micro-particle drugs of tetracycline hydrochloride, as a model drug, to examine the release behavior of nanofibers scaffold. The release profiles of drug loaded bead-on-string nanofibers demonstrated the possibility to alleviate the burst drug release by means of beads diameter control. - Highlights: • Bead diameter of bead-on-string electrospun nanofibers was controlled by varying solvent ratio and polymer concentration. • The effect of the addition of particle drugs on BD of bead-on-string electrospun nanofibers was studied. • The corresponding release behaviors of nanofibers with different BD loading micro-particle drugs were investigated. • Bead-on-string nanofibers with bigger BD could alleviate the initial burst release.

  12. Biosorption of americium by alginate beads

    International Nuclear Information System (INIS)

    Borba, Tania Regina de; Marumo, Julio Takehiro; Goes, Marcos Maciel de; Ferreira, Rafael Vicente de Padua; Sakata, Solange Kazumi

    2009-01-01

    The use of biotechnology to remove heavy metals from wastes plays great potential in treatment of radioactive wastes and therefore the aim of this study was to evaluate the biosorption of americium by alginate beads. Biosorption has been defined as the property of certain biomolecules to bind and remove selected ions or other molecules from aqueous solutions. The calcium alginate beads as biosorbent were prepared and analyzed for americium uptaking. The experiments were performed in different solution activity concentrations, pH and exposure time. The results suggest that biosorption process is more efficient at pH 4 and for 75, 150, 300 Bq/mL and 120 minutes were necessary to remove almost 100% of the americium-241 from the solution. (author)

  13. RF Bead Pull Measurements of the DQW

    CERN Document Server

    Jaume, Guillaume

    2015-01-01

    This report was written within the framework of the CERN Summer Student Program. It is focused on the Radio Frequency study of the Double Quarter Wave Crab Cavity [1] considered for the crab-crossing scheme of the LHC Luminosity upgrade [2]. HFSS simulation [3] and Bead-Pull Measurements technique were used for the characterization of the higher-order terms of the main deflecting mode.

  14. Spray drying of bead resins: feasibility tests

    International Nuclear Information System (INIS)

    Gay, R.L.; Grantham, L.F.; Jones, L.J.

    1984-01-01

    Rockwell International has developed a volume reduction system for low-level reactor wastes based on drying the wastes in a heated-air spray dryer. The drying of slurries of sodium sulfate, boric acid, and powdered ion exchange resins was demonstrated in previous tests. The drying of bead ion exchange resins can be especially difficult due to the relatively large size of bead resins (about 500 to 800 microns) and their natural affinity for water. This water becomes part of the pore structure of the resins and normally comprises 50 t 60 wt % of the resin weight. A 76-cm-diameter spray dryer was used for feasibility tests of spray drying of cation and anion bead resins. These resins were fed to the dryer in the as-received form (similar to dewatered resins) and as slurries. A dry, free-flowing product was produced in all the tests. The volume of the spray-dried product was one-half to one-third the volume of the as-received material. An economic analysis was made of the potential cost savings that can be achieved using the Rockwel spray dryer system. In-plant costs, transportation costs, and burial costs of spray-dried resins were compared to similar costs for disposal of dewatered resins. A typical utility producing 170 m 3 (6,000 ft 3 ) per year of dewatered resins can save $600,000 to $700,000 per year using this volume reduction system

  15. Investigation properties of superparamagnetic nanoparticles and magnetic field-dependent hyperthermia therapy

    Science.gov (United States)

    Hedayatnasab, Z.; Abnisa, F.; Daud, W. M. A. Wan

    2018-03-01

    The application of superparamagnetic nanoparticles as heating agents in hyperthermia therapy has made a therapeutic breakthrough in cancer treatment. The high efficiency of this magnetic hyperthermia therapy has derived from a great capability of superparamagnetic nanoparticles to generate focused heat in inaccessible tumors being effectively inactivated. The main challenges of this therapy are the improvement of the induction heating power of superparamagnetic nanoparticles and the control of the hyperthermia temperature in a secure range of 42 °C to 47 °C, at targeted area. The variation of these hyperthermia properties is principally dependent on the magnetic nanoparticles as well as the magnetic field leading to enhance the efficiency of magnetic hyperthermia therapy at targeted area and also avoid undue heating to healthy cells. The present study evaluates the magnetic hyperthermia therapy through the determination of superparamagnetic nanoparticles properties and magnetic field’ parameters.

  16. Discrete dipole approximation simulation of bead enhanced diffraction grating biosensor

    International Nuclear Information System (INIS)

    Arif, Khalid Mahmood

    2016-01-01

    We present the discrete dipole approximation simulation of light scattering from bead enhanced diffraction biosensor and report the effect of bead material, number of beads forming the grating and spatial randomness on the diffraction intensities of 1st and 0th orders. The dipole models of gratings are formed by volume slicing and image processing while the spatial locations of the beads on the substrate surface are randomly computed using discrete probability distribution. The effect of beads reduction on far-field scattering of 632.8 nm incident field, from fully occupied gratings to very coarse gratings, is studied for various bead materials. Our findings give insight into many difficult or experimentally impossible aspects of this genre of biosensors and establish that bead enhanced grating may be used for rapid and precise detection of small amounts of biomolecules. The results of simulations also show excellent qualitative similarities with experimental observations. - Highlights: • DDA was used to study the relationship between the number of beads forming gratings and ratio of first and zeroth order diffraction intensities. • A very flexible modeling program was developed to design complicated objects for DDA. • Material and spatial effects of bead distribution on surfaces were studied. • It has been shown that bead enhanced grating biosensor can be useful for fast detection of small amounts of biomolecules. • Experimental results qualitatively support the simulations and thus open a way to optimize the grating biosensors.

  17. Investigation of superparamagnetism in pure and chromium substituted cobalt nanoferrite

    Energy Technology Data Exchange (ETDEWEB)

    Raghasudha, M., E-mail: raghasudha_m@yahoo.co.in [Department of Chemistry, University College of Science, Osmania University, Hyderabad 500007, Telangana (India); Ravinder, D. [Department of Physics, University College of Science, Osmania University, Hyderabad 500007, Telangana (India); Veerasomaiah, P. [Department of Chemistry, University College of Science, Osmania University, Hyderabad 500007, Telangana (India)

    2016-12-15

    Nanostructured magnetic materials with the chemical composition CoFe{sub 2}O{sub 4} and CoCr{sub 0.9}Fe{sub 1.1}O{sub 4} were synthesized through Citrate-gel chemical synthesis with a crystallite size of 6.5 nm and 10.7 nm respectively. Structural characterization of the samples was performed by X-ray diffraction analysis and magnetic properties were studied using Vibrating Sample Magnetometer (VSM). Magnetization measurements as a function of applied magnetic field ±10 T at various temperatures 5 K, 25 K, 310 K and 355 K were carried out. Field cooled (FC) and Zero field cooled (ZFC) magnetization measurements under a magnetic field of 100 Oe for temperature ranging from 5–400 K were studied. The blocking temperature (T{sub b}) for both the ferrites was observed to be around 355 K. Below blocking temperature they showed ferromagnetic behavior and above which they are superparamagnetic in nature that favors their application in the biomedical field. The substitution of paramagnetic Cr{sup 3+} ions for magnetic Fe{sup 3+} ion in cobalt ferrite has resulted in a decrease in magnetization and the coercivity of the samples. CoCr{sub 0.9}Fe{sub 1.1}O{sub 4} nanoferrites with observed low coercivity of 338 Oe make them desirable in high frequency transformers due to their very soft magnetic behavior. - Highlights: • Particle size of CoFe{sub 2}O{sub 4} and CoCr{sub 0.9}Fe{sub 1.1}O{sub 4} is 6.5 nm and 10.7 nm respectively. • At 5 K and 25 K the materials were ferromagnetic in nature with high coercivity. • Materials show superparamagnetic behavior above room temperature. • Blocking temperature is at around 355 K where coercivity and remanence are zero. • Materials are suitable for hyperthermia cancer therapy.

  18. Ferroferric oxide/polystyrene (Fe3O4/PS superparamagnetic nanocomposite via facile in situ bulk radical polymerization

    Directory of Open Access Journals (Sweden)

    2010-03-01

    Full Text Available Organo-modified ferroferric oxide superparamagnetic nanoparticles, synthesized by the coprecipitation of superparamagnetic nanoparticles in presence of oleic acid (OA, were incorporated in polystyrene (PS by the facile in situ bulk radical polymerization by using 2,2-azobisisobutyronitrile (AIBN as initiator. The transmission electron microscopy (TEM analysis of the resultant uniform ferroferric oxide/polystyrene superparamagnetic nanocomposite (Fe3O4/PS showed that the superparamagnetic nanoparticles had been dispersed homogeneously in the polymer matrix due to the surface grafted polystyrene, confirmed by Fourier transform infrared (FT-IR spectroscopy and thermogravimetric analysis (TGA. The superparamagnetic property of the Fe3O4/PS nanocomposite was testified by the vibrating sample magnetometer (VSM analysis. The strategy developed is expected to be applied for the large-scale industrial manufacturing of the superparamagnetic polymer nanocomposite.

  19. HPMA and HEMA copolymer bead interactions with eukaryotic cells

    Directory of Open Access Journals (Sweden)

    Cristina D. Vianna-Soares

    2004-09-01

    Full Text Available Two different hydrophilic acrylate beads were prepared via aqueous suspension polymerization. Beads produced of a hydroxypropyl methacrylate (HPMA and ethyleneglycol methacrylate (EDMA copolymer were obtained using a polyvinyl alcohol suspending medium. Copolymers of 2hydroxyethyl methacrylate (HEMA, methyl methacrylate (MMA and ethyleneglycol methacrylate (EDMA beads were obtained using magnesium hydroxide as the suspending agent. Following characterization by scanning electron microscopy (SEM, nitrogen sorption analysis (NSA and mercury intrusion porosimetry (MIP, the beads were cultured with monkey fibroblasts (COS7 to evaluate their ability to support cell growth, attachment and adhesion. Cell growth behavior onto small HPMA/EDMA copolymer beads and large HEMA/MMA/EDMA copolymer beads is evaluated regarding their hidrophilicity/hidrophobicity and surface roughness.

  20. Microarray of DNA probes on carboxylate functional beads surface

    Institute of Scientific and Technical Information of China (English)

    黄承志; 李原芳; 黄新华; 范美坤

    2000-01-01

    The microarray of DNA probes with 5’ -NH2 and 5’ -Tex/3’ -NH2 modified terminus on 10 um carboxylate functional beads surface in the presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) is characterized in the preseni paper. it was found that the microarray capacity of DNA probes on the beads surface depends on the pH of the aqueous solution, the concentra-tion of DNA probe and the total surface area of the beads. On optimal conditions, the minimum distance of 20 mer single-stranded DNA probe microarrayed on beads surface is about 14 nm, while that of 20 mer double-stranded DNA probes is about 27 nm. If the probe length increases from 20 mer to 35 mer, its microarray density decreases correspondingly. Mechanism study shows that the binding mode of DNA probes on the beads surface is nearly parallel to the beads surface.

  1. Microarray of DNA probes on carboxylate functional beads surface

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The microarray of DNA probes with 5′-NH2 and 5′-Tex/3′-NH2 modified terminus on 10 m m carboxylate functional beads surface in the presence of 1-ethyl-3-(3-dimethylaminopropyl)- carbodiimide (EDC) is characterized in the present paper. It was found that the microarray capacity of DNA probes on the beads surface depends on the pH of the aqueous solution, the concentration of DNA probe and the total surface area of the beads. On optimal conditions, the minimum distance of 20 mer single-stranded DNA probe microarrayed on beads surface is about 14 nm, while that of 20 mer double-stranded DNA probes is about 27 nm. If the probe length increases from 20 mer to 35 mer, its microarray density decreases correspondingly. Mechanism study shows that the binding mode of DNA probes on the beads surface is nearly parallel to the beads surface.

  2. Configurational Statistics of Magnetic Bead Detection with Magnetoresistive Sensors

    DEFF Research Database (Denmark)

    Henriksen, Anders Dahl; Ley, Mikkel Wennemoes Hvitfeld; Flyvbjerg, Henrik

    2015-01-01

    Magnetic biosensors detect magnetic beads that, mediated by a target, have bound to a functionalized area. This area is often larger than the area of the sensor. Both the sign and magnitude of the average magnetic field experienced by the sensor from a magnetic bead depends on the location...... of the bead relative to the sensor. Consequently, the signal from multiple beads also depends on their locations. Thus, a given coverage of the functionalized area with magnetic beads does not result in a given detector response, except on the average, over many realizations of the same coverage. We present...... a systematic theoretical analysis of how this location-dependence affects the sensor response. The analysis is done for beads magnetized by a homogeneous in-plane magnetic field. We determine the expected value and standard deviation of the sensor response for a given coverage, as well as the accuracy...

  3. Single-cell nanotoxicity assays of superparamagnetic iron oxide nanoparticles.

    Science.gov (United States)

    Eustaquio, Trisha; Leary, James F

    2012-01-01

    Properly evaluating the nanotoxicity of nanoparticles involves much more than bulk-cell assays of cell death by necrosis. Cells exposed to nanoparticles may undergo repairable oxidative stress and DNA damage or be induced into apoptosis. Exposure to nanoparticles may cause the cells to alter their proliferation or differentiation or their cell-cell signaling with neighboring cells in a tissue. Nanoparticles are usually more toxic to some cell subpopulations than others, and toxicity often varies with cell cycle. All of these facts dictate that any nanotoxicity assay must be at the single-cell level and must try whenever feasible and reasonable to include many of these other factors. Focusing on one type of quantitative measure of nanotoxicity, we describe flow and scanning image cytometry approaches to measuring nanotoxicity at the single-cell level by using a commonly used assay for distinguishing between necrotic and apoptotic causes of cell death by one type of nanoparticle. Flow cytometry is fast and quantitative, provided that the cells can be prepared into a single-cell suspension for analysis. But when cells cannot be put into suspension without altering nanotoxicity results, or if morphology, attachment, and stain location are important, a scanning image cytometry approach must be used. Both methods are described with application to a particular type of nanoparticle, a superparamagnetic iron oxide nanoparticle (SPION), as an example of how these assays may be applied to the more general problem of determining the effects of nanomaterial exposure to living cells.

  4. Detection of ''beading faults'' in welded tubes

    International Nuclear Information System (INIS)

    Mondot, J.

    In the steel tube industry the word ''beading'' refers to a highly localised leak affecting the welded zone. During the pneumatic test its flow rate is generally very low no more than a few thousandths of a mm 3 /second. Detection of such a fault by this test is consequently slow, and those which are choked or at the limit of leakage may escape detection. For greater safety, the tube technician is now using non-destructive testing methods such as eddy-currents and ultrasonics [fr

  5. Creating nanoshell on the surface of titanium hydride bead

    Directory of Open Access Journals (Sweden)

    PAVLENKO Vyacheslav Ivanovich

    2016-12-01

    Full Text Available The article presents data on the modification of titanium hydride bead by creating titanium nanoshell on its surface by ion-plasma vacuum magnetron sputtering. To apply titanium nanoshell on the titanium hydride bead vacuum coating plant of multifunctional nanocomposite coatings QVADRA 500 located in the center of high technology was used. Analysis of the micrographs of the original surface of titanium hydride bead showed that the microstructure of the surface is flat, smooth, in addition the analysis of the microstructure of material surface showed the presence of small porosity, roughness, mainly cavities, as well as shallow longitudinal cracks. The presence of oxide film in titanium hydride prevents the free release of hydrogen and fills some micro-cracks on the surface. Differential thermal analysis of both samples was conducted to determine the thermal stability of the initial titanium hydride bead and bead with applied titanium nanoshell. Hydrogen thermal desorption spectra of the samples of the initial titanium hydride bead and bead with applied titanium nanoshell show different thermal stability of compared materials in the temperature range from 550 to 860о C. Titanium nanoshells applied in this way allows increasing the heat resistance of titanium hydride bead – the temperature of starting decomposition is 695о C and temperature when decomposition finishes is more than 1000о C. Modified in this way titanium hydride bead can be used as a filler in the radiation protective materials used in the construction or upgrading biological protection of nuclear power plants.

  6. Microchannel conductivity measurements in microchip for on line monitoring of dephosphorylation rates of organic phosphates using paramagnetic-beads linked alkaline phosphatase.

    Science.gov (United States)

    Kechadi, Mohammed; Sotta, Bruno; Gamby, Jean

    2015-01-01

    This paper presents the use of polymer coated microelectrodes for the realtime conductivity monitoring in a microchannel photoablated through the polymer without contact. Based on this strategy, a small conductometry sensor has been developed to record in time conductivity variation when an enzymatic reaction occurs through the channel. The rate constant determination, k2, for the dephosphorylation of organic phosphate-alkaline phosphatase-superparamagnetic beads complex using chemically different substrates such as adenosine monoesterphosphate, adenosine diphosphate and adenosine triphosphate was taken as an example to demonstrate selectivity and sensivity of the detection scheme. The k2 value measured for each adenosine phosphate decreases from 39 to 30 s(-1) in proportion with the number (3, 2 and 1) of attached phosphate moiety, thus emphasizing the steric hindrance effect on kinetics. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Magnetoviscoelastic characteristics of superparamagnetic oxides (Fe, Ni) based ferrofluids

    Science.gov (United States)

    Katiyar, Ajay; Dhar, Purbarun; Nandi, Tandra; Das, Sarit K.

    2017-08-01

    Ferrofluids have been popular among the academic and scientific communities owing to their intelligent physical characteristics under external stimuli and are in fact among the first nanotechnology products to be employed in real world applications. However, studies on the magnetoviscoelastic behavior of concentrated ferrofluids, especially of superparamagnetic oxides of iron and nickel are rare. The present article comprises the formulation of magneto-colloids utilizing the three various metal oxides nanoparticles viz. Iron (II, III) oxide (Fe3O4), Iron (III) oxide (Fe2O3) and Nickel oxide (NiO) in oil. Iron (II, III) oxide based colloids demonstrate high magnetoviscous characteristics over the other oxides based colloids under external magnetic fields. The maximum magnitude of yield stress and viscosity is found to be 3.0 kPa and 2.9 kPa.s, respectively for iron (II, III) oxide based colloids at 2.6 vol% particle concentration and 1.2 T magnetic field. Experimental investigations reveal that the formulated magneto-nanocolloids are stable, even in high magnetic fields and almost reversible when exposed to rising and drop of magnetic fields of the same magnitude. Observations also reveal that the elastic behavior dominates over the viscous behavior with enhanced relaxation and creep characteristics under the magnetic field. The effect of temperature on viscosity and yield stress of magneto-nanocolloids under magnetic fields has also been discussed. Thus, the present findings have potential applications in various fields such as electromagnetic clutch and brakes of automotive, damping, sealing, optics, nanofinishing etc.

  8. TiO2 beads and TiO2-chitosan beads for urease immobilization

    International Nuclear Information System (INIS)

    Ispirli Doğaç, Yasemin; Deveci, İlyas; Teke, Mustafa; Mercimek, Bedrettin

    2014-01-01

    The aim of the present study is to synthesize TiO 2 beads for urease immobilization. Two different strategies were used to immobilize the urease on TiO 2 beads. In the first method (A), urease enzyme was immobilized onto TiO 2 beads by adsorption and then crosslinking. In the second method (B), TiO 2 beads were coated with chitosan-urease mixture. To determine optimum conditions of immobilization, different parameters were investigated. The parameters of optimization were initial enzyme concentration (0.5; 1; 1.5; 2 mg/ml), alginate concentration (1; 2; 3%), glutaraldehyde concentration (1; 2; 3% v/v) and chitosan concentration (2; 3; 4 mg/ml). The optimum enzyme concentrations were determined as 1.5 mg/ml for A and 1.0 mg/ml for B. The other optimum conditions were found 2.0% (w/v) for alginate concentration (both A and B); 3.0 mg/ml for chitosan concentration (B) and 2.0% (v/v) for glutaraldehyde concentration (A). The optimum temperature (20-60 °C), optimum pH (3.0-10.0), kinetic parameters, thermal stability (4–70 °C), pH stability (4.0-9.0), operational stability (0-230 min) and reusability (20 times) were investigated for characterization. The optimum temperatures were 30 °C (A), 40 °C (B) and 35 °C (soluble). The temperature profiles of the immobilized ureases were spread over a large area. The optimum pH values for the soluble urease and immobilized urease prepared by using methods (A) and (B) were found to be 7.5, 7.0, 7.0, respectively. The thermal stabilities of immobilized enzyme sets were studied and they maintained 50% activity at 65 °C. However, at this temperature free urease protected only 15% activity. - Highlights: • TiO 2 and TiO 2 -chitosan beads for urease immobilization have been prepared and characterized. • The beads used in this work are good matrices for the immobilization of urease. • The immobilized urease was shown to have good properties and stabilities (pH and thermal stability, operational stability). • The 50

  9. Bead Collage: An Arts-Based Research Method

    Science.gov (United States)

    Kay, Lisa

    2013-01-01

    In this paper, "bead collage," an arts-based research method that invites participants to reflect, communicate and construct their experience through the manipulation of beads and found objects is explained. Emphasizing the significance of one's personal biography and experiences as a researcher, I discuss how my background as an…

  10. Growth and morphology of thermophilic dairy starters in alginate beads.

    Science.gov (United States)

    Lamboley, Laurence; St-Gelais, Daniel; Champagne, Claude P; Lamoureux, Maryse

    2003-06-01

    The aim of this research was to produce concentrated biomasses of thermophilic lactic starters using immobilized cell technology (ICT). Fermentations were carried out in milk using pH control with cells microentrapped in alginate beads. In the ICT fermentations, beads represented 17% of the weight. Some assays were carried out with free cells without pH control, in order to compare the ICT populations with those of classical starters. With Streptococcus thermophilus, overall populations in the fermentor were similar, but maximum bead population for (8.2 x 10(9) cfu/g beads) was 13 times higher than that obtained in a traditional starter (4.9 x 10(8) cfu/ml). For both Lactobacillus helveticus strains studied, immobilized-cell populations were about 3 x 10(9) cfu/g beads. Production of immobilized Lb. bulgaricus 210R strain was not possible, since no increases in viable counts occurred in beads. Therefore, production of concentrated cell suspension in alginate beads was more effective for S. thermophilus. Photomicrographs of cells in alginate beads demonstrated that, while the morphology of S. thermophilus remained unchanged during the ICT fermentation, immobilized cells of Lb. helveticus appeared wider. In addition, cells of Lb. bulgaricus were curved and elongated. These morphological changes would also impair the growth of immobilized lactobacilli.

  11. Towards a programmable magnetic bead microarray in a microfluidic channel

    DEFF Research Database (Denmark)

    Smistrup, Kristian; Bruus, Henrik; Hansen, Mikkel Fougt

    2007-01-01

    to use larger currents and obtain forces of longer range than from thin current lines at a given power limit. Guiding of magnetic beads in the hybrid magnetic separator and the construction of a programmable microarray of magnetic beads in the microfluidic channel by hydrodynamic focusing is presented....

  12. Towards Hypoxia-responsive Drug-eluting Embolization Beads.

    Science.gov (United States)

    Ashrafi, Koorosh; Heaysman, Clare L; Phillips, Gary J; Lloyd, Andrew W; Lewis, Andrew L

    2017-05-30

    Drug release from chemoembolization microspheres stimulated by the presence of a chemically reducing environment may provide benefits for targeting drug resistant and metastatic hypoxic tumours. A water-soluble disulfide-based bifunctional cross-linker bis(acryloyl)-(l)-cystine (BALC) was synthesised, characterised and incorporated into a modified poly(vinyl) alcohol (PVA) hydrogel beads at varying concentrations using reverse suspension polymerisation. The beads were characterised to confirm the amount of cross-linker within each formulation and its effects on the bead properties. Elemental and UV/visible spectroscopic analysis confirmed the incorporation of BALC within the beads and sizing studies showed that in the presence of a reducing agent, all bead formulations increased in mean diameter. The BALC beads could be loaded with doxorubicin hydrochloride and amounts in excess of 300mg of drug per mL of hydrated beads could be achieved but required conversion of the carboxylic acid groups of the BALC to their sodium carboxylate salt forms. Elution of doxorubicin from the beads demonstrated a controlled release via ionic exchange. Some formulations exhibited an increase in size and release of drug in the presence of a reducing agent, and therefore demonstrated the ability to respond to an in vitro reducing environment. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  13. Concepts for increasing gentamicin release from handmade bone cement beads

    NARCIS (Netherlands)

    Rasyid, Hermawan N; van der Mei, Henny C; Frijlink, Henderik W; Soegijoko, Soegijardjo; Van Horn, Jim R; Busscher, Hendrik; Neut, Daniëlle

    2009-01-01

    BACKGROUND AND PURPOSE: Commercial gentamicin-loaded bone cement beads (Septopal) constitute an effective delivery system for local antibiotic therapy. These beads are not available in all parts of the world, and are too expensive for frequent use in others. Thus, orthopedic surgeons worldwide make

  14. Beaded Fiber Mats of PVA Containing Unsaturated Heteropoly Salt

    Institute of Scientific and Technical Information of China (English)

    Guo Cheng YANG; Yan PAN; Jian GONG; Chang Lu SHAO; Shang Bin WEN; Chen SHAO; Lun Yu QU

    2004-01-01

    Poly(vinyl alcohol) (PVA) fiber mats containing unsaturated heteropoly salt was prepared for the first time. IR, X-ray diffraction and SEM photographs characterized the beaded fiber mats.The viscoelasticity and the conductivity of the solution were the key factors that influence the formation of the beaded fiber mats.

  15. Optimization of weld bead geometry of MS plate

    Indian Academy of Sciences (India)

    The considered specimen was checked to harmonize the optimum setting between input factors, for example, welding current, open circuit voltage, and thickness of plate, with respect to obtaining prosperous weld strength as well as bead geometry quality characteristics, for example, tensile strength, bead width, ...

  16. SparseBeads data: benchmarking sparsity-regularized computed tomography

    DEFF Research Database (Denmark)

    Jørgensen, Jakob Sauer; Coban, Sophia B.; Lionheart, William R. B.

    2017-01-01

    -regularized reconstruction. A collection of 48 x-ray CT datasets called SparseBeads was designed for benchmarking SR reconstruction algorithms. Beadpacks comprising glass beads of five different sizes as well as mixtures were scanned in a micro-CT scanner to provide structured datasets with variable image sparsity levels...

  17. Entrapment of laurel lipase in chitosan hydrogel beads.

    Science.gov (United States)

    Yagar, Hulya; Balkan, Ugur

    2017-08-01

    Laurel seed lipase was entrapped within chitosan beads with ionotropic gelatin method using tripolyphosphate (TPP) as multivalent covalent counter ion. Immobilization yield was 78%. First, optimum immobilization conditions were determined, and morphology of chitosan beads was characterized by scanning electron microscopy. Optimum pH and temperature were evaluated as 6.0 and 40 °C, respectively. The immobilized beads saved about 55% of its activities at 60° while saved about 32% at 70 °C for 30 min. V max /K m values were determined as 31.75 and 2.87 using olive oil as substrate for immobilized beads and free enzyme, respectively. Immobilized beads showed the activities during 30 days at +4 °C.

  18. A NOVEL APPROACH TO SYNTHESIZE CHITOSAN BEADS CROSSLINKED BY EPICHLOROHYDRIN

    Institute of Scientific and Technical Information of China (English)

    WANG Yongjian; BAI Shu; SUN Yan

    2001-01-01

    The present investigation describes a novel method for preparing spherical chitosan particles based on crosslinking with epichlorohydrin. Certain amount of pre-crosslinking agent was added to form chitosan gels by traditional inverse phase suspension polymerization. Then the gels were crosslinked by epichlorohydrin at basic condition to obtain chitosan beads. The effects of reaction conditions, such as crosslinking time, the amount of crosslinking agent and the NaOtt concentration,on the physical properties of the chitosan beads were investigated. The beads were found to have more amino groups in the polymer chains than the beads crosslinked by glutaraldehyde. The capacity for copper ions is as high as 40mg/g. The beads have good mechanical strength and can be reused.

  19. A NOVEL APPROACH TO SYNTHESIZE CHITOSAN BEADS CROSSLINKED BY EPICHLOROHYDRIN

    Institute of Scientific and Technical Information of China (English)

    WANGYongjina; BAIShu; 等

    2001-01-01

    The present investigation describes a novel method for preparing spherical chitosan particles based on crosslinking with epichlorohydrin.Certain amount of pre-crosslinking agent was added to form chitosan gels by traditional inverse phase suspension polymerization.Then the gels were crosslinked by epichlorohydrin at basic condition to obtain chitosan beads.The effects of reaction conditions,such as crosslinking time,the amount of crosslinking agent and the NaOH concentration,on the physical properties of the chitosan beads were investigated.The beads were found to have more amino groups in the polymer chains than the beads crosslinked by glutaraldehyde.The capacity for copper ions in as high as 40mg/g,The beads have good mechanical strength and can be reused.

  20. Bead magnetorelaxometry with an on-chip magnetoresistive sensor

    DEFF Research Database (Denmark)

    Dalslet, Bjarke Thomas; Damsgaard, Christian Danvad; Donolato, Marco

    2011-01-01

    Magnetorelaxometry measurements on suspensions of magnetic beads are demonstrated using a planar Hall effect sensor chip embedded in a microfluidic system. The alternating magnetic field used for magnetizing the beads is provided by the sensor bias current and the complex magnetic susceptibility...... spectra are recorded as the 2nd harmonic of the sensor response. The complex magnetic susceptibility signal appears when a magnetic bead suspension is injected, it scales with the bead concentration, and it follows the Cole-Cole expression for Brownian relaxation. The complex magnetic susceptibility...... signal resembles that from conventional magnetorelaxometry done on the same samples apart from an offset in Brownian relaxation frequency. The time dependence of the signal can be rationalized as originating from sedimented beads....

  1. Graphene Oxide Conjugated Magnetic Beads for RNA Extraction.

    Science.gov (United States)

    Pham, Xuan-Hung; Baek, Ahruem; Kim, Tae Han; Lee, Sang Hun; Rho, Won-Yeop; Chung, Woo-Jae; Kim, Dong-Eun; Jun, Bong-Hyun

    2017-08-04

    A magnetic material that consists of silica-coated magnetic beads conjugated with graphene oxide (GO) was successfully prepared for facile ribonucleic acid (RNA) extraction. When the GO-modified magnetic beads were applied to separate the RNA from the lysed cell, the cellular RNAs were readily adsorbed to and readily desorbed from the surface of the GO-modified magnetic beads by urea. The amount of RNA extracted by the GO-modified magnetic beads was ≈170 % as much as those of the control extracted by a conventional phenol-based chaotropic solution. These results demonstrate that the facile method of RNA separation by using GO-modified magnetic beads as an adsorbent is an efficient and simple way to purify intact cellular RNAs and/or microRNA from cell lysates. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Oxytetracycline removal from water by novel microbial embedding gel beads

    Science.gov (United States)

    Wu, Nan; Pan, Peng; Zeng, Ming; Wang, Wei; Xu, Chenshan; Zhang, Zongpeng; Liu, Xinyuan; Wang, Yichao

    2018-01-01

    As a common antibiotic in aquatic environment, excessive oxytetracycline (OTC) is urgent to be removed due to its great biological toxicity. Compared with the traditional activated sludge, microbial embedding can enhance the treating efficiency. In this study, novel microbial embedding gel beads were produced with the additional agent of cyclodextrin (CD). Results show that CD could increase the mass transfer of OTC into gel beads, possibly because of its strong affinity for organic matters. In terms of OTC biodegradation, gel beads with CD were comparable to gel beads without CD, while the former’s sucrose removal efficiency was higher than the latter. The biodegradation of OTC only occurred in the presence of sucrose. The respiration test also confirmed these findings. Overall, the produced novel gel beads modified with CD could improve the removal performance of OTC.

  3. Design of systems for handling radioactive ion exchange resin beads

    International Nuclear Information System (INIS)

    Shapiro, S.A.; Story, G.L.

    1979-01-01

    The flow of slurries in pipes is a complex phenomenon. There are little slurry data available on which to base the design of systems for radioactive ion exchange resin beads and, as a result, the designs vary markedly in operating plants. With several plants on-line, the opportunity now exists to evaluate the designs of systems handling high activity spent resin beads. Results of testing at Robbins and Meyers Pump Division to quantify the behavior of resin bead slurries are presented. These tests evaluated the following slurry parameters; resin slurry velocity, pressure drop, bead degradation, and slurry concentration effects. A discussion of the general characteristics of resin bead slurries is presented along with a correlation to enable the designer to establish the proper flowrate for a given slurry composition and flow regime as a function of line size. Guidelines to follow in designing a resin handling system are presented

  4. Multiple functionalities of Ni nanoparticles embedded in carboxymethyl guar gum polymer: catalytic activity and superparamagnetism

    International Nuclear Information System (INIS)

    Sardar, Debasmita; Sengupta, Manideepa; Bordoloi, Ankur; Ahmed, Md. A.; Neogi, S.K.; Bandyopadhyay, Sudipta; Jain, Ruchi; Gopinath, Chinnakonda S.; Bala, Tanushree

    2017-01-01

    Highlights: • Ni nanoparticles were synthesized in polymer to form Ni-Polymer composite. • Ni nanoparticles retain their superparamagnetism in the composite. • Ni-Polymer composites showed catalytic activity. - Abstract: Composites comprising of metallic nanoparticles in polymer matrices have allured significant importance due to multifunctionalities. Here a simple protocol has been described to embed Ni nanoparticles in carboxymethyl guar gum (CMGG) polymer. The composite formation helps in the stabilization of Ni nanoparticles which are otherwise prone towards aerial oxidation. Further the nanoparticles retain their superparamagnetic nature and catalytic capacity. Ni-Polymer composite catalyses the reduction of 4-Nitrophenol to 4-Aminophenol very efficiently in presence of NaBH_4, attaining a complete conversion under some experimental conditions. Ni-Polymer composite is well characterized using UV–vis spectroscopy, FTIR, XPS, powder XRD, TGA, SEM and TEM. A detailed magnetic measurement using superconducting quantum interference device-vibrating sample magnetometer (SQUID-VSM) reveals superparamagnetic behaviour of the composite.

  5. Metallic gold beads in hyaluronic acid

    DEFF Research Database (Denmark)

    Pedersen, Dan Sonne; Tran, Thao Phuong; Smidt, Kamille

    2013-01-01

    . In conclusion, our findings support that bio-liberation of gold from metallic gold surfaces have anti-inflammatory properties similar to classic gold compounds, warranting further studies into the pharmacological potential of this novel gold-treatment and the possible synergistic effects of hyaluronic acid....... by exploiting macrophage-induced liberation of gold ions (dissolucytosis) from gold surfaces. Injecting gold beads in hyaluronic acid (HA) as a vehicle into the cavities of the brain can delay clinical signs of disease progression in the MS model, experimental autoimmune encephalitis (EAE). This study...... investigates the anti-inflammatory properties of metallic gold/HA on the gene expression of tumor necrosis factor (Tnf-α), Interleukin (Il)-1β, Il-6, Il-10, Colony-stimulating factor (Csf)-v2, Metallothionein (Mt)-1/2, Bcl-2 associated X protein (Bax) and B cell lymphoma (Bcl)-2 in cultured J774 macrophages...

  6. On-chip signal amplification of magnetic bead-based immunoassay by aviating magnetic bead chains.

    Science.gov (United States)

    Jalal, Uddin M; Jin, Gyeong Jun; Eom, Kyu Shik; Kim, Min Ho; Shim, Joon S

    2017-11-06

    In this work, a Lab-on-a-Chip (LOC) platform is used to electromagnetically actuate magnetic bead chains for an enhanced immunoassay. Custom-made electromagnets generate a magnetic field to form, rotate, lift and lower the magnetic bead chains (MBCs). The cost-effective, disposable LOC platform was made with a polymer substrate and an on-chip electrochemical sensor patterned via the screen-printing process. The movement of the MBCs is controlled to improve the electrochemical signal up to 230% when detecting beta-type human chorionic gonadotropin (β-hCG). Thus, the proposed on-chip MBC-based immunoassay is applicable for rapid, qualitative electrochemical point-of-care (POC) analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Inhibitive Effect of antibiotic-loaded beads to cure chronic osteomyelitis in developing country : Hand-made vs commercial beads

    NARCIS (Netherlands)

    Rasyid, Hcrmawan N.; Van Horn, Jim R.; Van der Mei, Henny C.; Soegijoko, Sooegijardjo; Busscher, Henk J.; Neut, Danielle; Ibrahim, F; Osman, NAA; Usman, J; Kadri, NA

    2007-01-01

    Local antibiotic-loaded beads have been approved for standard treatment of orthopaedic pathogens, especially chronic osteomyelitis. Septopal (R), the only commercial local antibiotic bead available on the market, is expensive and contains only gentamicin. This study aimed to compare the in vitro

  8. Energy efficient bead milling of microalgae: Effect of bead size on disintegration and release of proteins and carbohydrates.

    Science.gov (United States)

    Postma, P R; Suarez-Garcia, E; Safi, C; Yonathan, K; Olivieri, G; Barbosa, M J; Wijffels, R H; Eppink, M H M

    2017-01-01

    The disintegration of three industry relevant algae (Chlorella vulgaris, Neochloris oleoabundans and Tetraselmis suecica) was studied in a lab scale bead mill at different bead sizes (0.3-1mm). Cell disintegration, proteins and carbohydrates released into the water phase followed a first order kinetics. The process is selective towards proteins over carbohydrates during early stages of milling. In general, smaller beads led to higher kinetic rates, with a minimum specific energy consumption of ⩽0.47kWhkg DW -1 for 0.3mm beads. After analysis of the stress parameters (stress number and stress intensity), it appears that optimal disintegration and energy usage for all strains occurs in the 0.3-0.4mm range. During the course of bead milling, the native structure of the marker protein Rubisco was retained, confirming the mildness of the disruption process. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  9. DWPF GLASS BEADS AND GLASS FRIT TRANSPORT DEMONSTRATION

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, D; Bradley Pickenheim, B

    2008-11-24

    DWPF is considering replacing irregularly shaped glass frit with spherical glass beads in the Slurry Mix Evaporator (SME) process to decrease the yield stress of the melter feed (a non-Newtonian Bingham Plastic). Pilot-scale testing was conducted on spherical glass beads and glass frit to determine how well the glass beads would transfer when compared to the glass frit. Process Engineering Development designed and constructed the test apparatus to aid in the understanding and impacts that spherical glass beads may have on the existing DWPF Frit Transfer System. Testing was conducted to determine if the lines would plug with the glass beads and the glass frit slurry and what is required to unplug the lines. The flow loop consisted of vertical and horizontal runs of clear PVC piping, similar in geometry to the existing system. Two different batches of glass slurry were tested: a batch of 50 wt% spherical glass beads and a batch of 50 wt% glass frit in process water. No chemicals such as formic acid was used in slurry, only water and glass formers. The glass beads used for this testing were commercially available borosilicate glass of mesh size -100+200. The glass frit was Frit 418 obtained from DWPF and is nominally -45+200 mesh. The spherical glass beads did not have a negative impact on the frit transfer system. The transferring of the spherical glass beads was much easier than the glass frit. It was difficult to create a plug with glass bead slurry in the pilot transfer system. When a small plug occurred from setting overnight with the spherical glass beads, the plug was easy to displace using only the pump. In the case of creating a man made plug in a vertical line, by filling the line with spherical glass beads and allowing the slurry to settle for days, the plug was easy to remove by using flush water. The glass frit proved to be much more difficult to transfer when compared to the spherical glass beads. The glass frit impacted the transfer system to the point

  10. DWPF GLASS BEADS AND GLASS FRIT TRANSPORT DEMONSTRATION

    International Nuclear Information System (INIS)

    Adamson, D.; Pickenheim, Bradley

    2008-01-01

    DWPF is considering replacing irregularly shaped glass frit with spherical glass beads in the Slurry Mix Evaporator (SME) process to decrease the yield stress of the melter feed (a non-Newtonian Bingham Plastic). Pilot-scale testing was conducted on spherical glass beads and glass frit to determine how well the glass beads would transfer when compared to the glass frit. Process Engineering Development designed and constructed the test apparatus to aid in the understanding and impacts that spherical glass beads may have on the existing DWPF Frit Transfer System. Testing was conducted to determine if the lines would plug with the glass beads and the glass frit slurry and what is required to unplug the lines. The flow loop consisted of vertical and horizontal runs of clear PVC piping, similar in geometry to the existing system. Two different batches of glass slurry were tested: a batch of 50 wt% spherical glass beads and a batch of 50 wt% glass frit in process water. No chemicals such as formic acid was used in slurry, only water and glass formers. The glass beads used for this testing were commercially available borosilicate glass of mesh size -100+200. The glass frit was Frit 418 obtained from DWPF and is nominally -45+200 mesh. The spherical glass beads did not have a negative impact on the frit transfer system. The transferring of the spherical glass beads was much easier than the glass frit. It was difficult to create a plug with glass bead slurry in the pilot transfer system. When a small plug occurred from setting overnight with the spherical glass beads, the plug was easy to displace using only the pump. In the case of creating a man made plug in a vertical line, by filling the line with spherical glass beads and allowing the slurry to settle for days, the plug was easy to remove by using flush water. The glass frit proved to be much more difficult to transfer when compared to the spherical glass beads. The glass frit impacted the transfer system to the point

  11. Magnetoviscoelastic characteristics of superparamagnetic oxides (Fe, Ni) based ferrofluids

    Energy Technology Data Exchange (ETDEWEB)

    Katiyar, Ajay, E-mail: ajay_k@ric.drdo.in [Research and Innovation Centre (DRDO), IIT Madras Research Park, Chennai 600113 (India); Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Dhar, Purbarun [Department of Mechanical Engineering, Indian Institute of Technology Ropar, Rupnagar, Punjab 140001 (India); Nandi, Tandra [Defence Materials and Stores Research and Development Establishment (DRDO), G.T. Road, Kanpur 208013 (India); Das, Sarit K. [Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Department of Mechanical Engineering, Indian Institute of Technology Ropar, Rupnagar, Punjab 140001 (India)

    2017-08-15

    Highlights: • The magnetoviscous effect in ferrofluids in the presence of magnetic field is investigated. • Oxides of Fe and Ni are dispersed in oil to formulate the ferrofluids. • Drastic enhancement in the yield stress and viscosity under the magnetic field is observed for Fe{sub 3}O{sub 4}-based ferrofluids. • Viscoelastic properties of the formulated ferrofluids demonstrate the strong function of magnetic field. • The increase in temperature reduces the magneto-viscous effect in ferrofluids under the magnetic field. - Abstract: Ferrofluids have been popular among the academic and scientific communities owing to their intelligent physical characteristics under external stimuli and are in fact among the first nanotechnology products to be employed in real world applications. However, studies on the magnetoviscoelastic behavior of concentrated ferrofluids, especially of superparamagnetic oxides of iron and nickel are rare. The present article comprises the formulation of magneto-colloids utilizing the three various metal oxides nanoparticles viz. Iron (II, III) oxide (Fe{sub 3}O{sub 4}), Iron (III) oxide (Fe{sub 2}O{sub 3}) and Nickel oxide (NiO) in oil. Iron (II, III) oxide based colloids demonstrate high magnetoviscous characteristics over the other oxides based colloids under external magnetic fields. The maximum magnitude of yield stress and viscosity is found to be 3.0 kPa and 2.9 kPa.s, respectively for iron (II, III) oxide based colloids at 2.6 vol% particle concentration and 1.2 T magnetic field. Experimental investigations reveal that the formulated magneto-nanocolloids are stable, even in high magnetic fields and almost reversible when exposed to rising and drop of magnetic fields of the same magnitude. Observations also reveal that the elastic behavior dominates over the viscous behavior with enhanced relaxation and creep characteristics under the magnetic field. The effect of temperature on viscosity and yield stress of magneto

  12. Measuring and modeling the magnetic settling of superparamagnetic nanoparticle dispersions.

    Science.gov (United States)

    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

  13. Superparamagnetic nanoparticles for enhanced magnetic resonance and multimodal imaging

    Science.gov (United States)

    Sikma, Elise Ann Schultz

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

  14. Calcium Pectinate Beads Formation: Shape and Size Analysis

    Directory of Open Access Journals (Sweden)

    Boon-Beng Lee

    2014-04-01

    Full Text Available The aim of this study was to investigate the inter-relationship between process variables and the size and shape of pectin solution droplets upon detachment from a dripping tip as well as Ca-pectinate beads formed after gelation via image analysis. The sphericity factor (SF of the droplets was generally smaller than 0.05. There was no specific trend between the SF of the droplets and the pectin concentration or the dripping tip radius. The SF the beads formed from high-concentration pectin solutions and a small dripping tip was smaller than 0.05. The results show that the Reynolds number and Ohnesorge number of the droplets fall within the operating region for forming spherical beads in the shape diagram, with the exception to the lower boundary. The lower boundary of the operating region has to be revised to Oh = 2.3. This is because the critical viscosity for Ca-pectinate bead formation is higher than that of Ca-alginate beads. On the other hand, the radius of the droplets and beads increased as the dripping tip radius increased. The bead radius can easily be predicted by Tate’s law equation.

  15. Self-organizing magnetic beads for biomedical applications

    International Nuclear Information System (INIS)

    Gusenbauer, Markus; Kovacs, Alexander; Reichel, Franz; Exl, Lukas; Bance, Simon; Özelt, Harald; Schrefl, Thomas

    2012-01-01

    In the field of biomedicine magnetic beads are used for drug delivery and to treat hyperthermia. Here we propose to use self-organized bead structures to isolate circulating tumor cells using lab-on-chip technologies. Typically blood flows past microposts functionalized with antibodies for circulating tumor cells. Creating these microposts with interacting magnetic beads makes it possible to tune the geometry in size, position and shape. We developed a simulation tool that combines micromagnetics and discrete particle dynamics, in order to design micropost arrays made of interacting beads. The simulation takes into account the viscous drag of the blood flow, magnetostatic interactions between the magnetic beads and gradient forces from external aligned magnets. We developed a particle–particle particle–mesh method for effective computation of the magnetic force and torque acting on the particles. - Highlights: ► We propose to use self-organized bead structures to isolate circulating tumor cells. ► Flexible ways are important to get a high probability of catching cancer cells. ► The beads make it possible to tune the geometry in size position and shape.

  16. Ecohydraulics of Strings and Beads in Bedrock Rivers

    Science.gov (United States)

    Wohl, E.

    2016-12-01

    Twenty years ago, Jack Stanford and others described rivers in bedrock canyons as resembling beads on a string when viewed in planform. The beads are relatively wide, low gradient river segments with floodplains, whereas the strings are the intervening steep, narrow river segments with minimal floodplain development. This pattern of longitudinal variations in channel and valley morphology along bedrock canyon rivers is very common, from small channels to major rivers such as the Colorado. Basic understanding of river ecosystems, as well as limited studies, indicates that the beads are more retentive and biologically productive. Although both strings and beads can provide habitat for diverse organisms, strings are more likely to serve as migration corridors, whereas beads provide spawning and nursery habitat, facilitate lateral (channel-floodplain) and vertical (channel-hyporheic) exchanges and associated habitat diversity, and retain dissolved and particulate organic matter. Recognition of the different characteristics and functions of strings and beads can be used to identify their spatial distribution along a river or within a river network and the hydraulically driven processes that sustain channel form, water quality, and biota within strings and beads. Diverse modeling approaches can then be used to quantify the fluxes of water and sediment needed to maintain these hydraulically driven processes. This conceptual framework is illustrated using examples from mountain streams in the Southern Rockies and canyon rivers in the southwestern United States.

  17. Simulation of non-linear coaxial line using ferrite beads

    International Nuclear Information System (INIS)

    Furuya, S.; Matsumoto, H.; Tachi, K.; Takano, S.; Irisawa, J.

    2002-01-01

    A ferrite sharpener is a non-linear coaxial line using ferrite beads, which produces high-voltage, high-dV/dt pulses. We have been examining the characteristics of ferrite sharpeners experimentally, varying various parameters. Also we have made the simulation of the ferrite sharpener and compared the predictions with the experimental results in detail to analyze the characteristics of the sharpener. In this report, calculating the magnetization M of the ferrite bead, we divide the bead into n sections radially instead of adopting M at the average radius in the previous report. (author)

  18. Random glycopeptide bead libraries for seromic biomarker discovery

    DEFF Research Database (Denmark)

    Kracun, Stjepan Kresimir; Cló, Emiliano; Clausen, Henrik

    2010-01-01

    have developed a random glycopeptide bead library screening platform for detection of autoantibodies and other binding proteins. Libraries were build on biocompatible PEGA beads including a safety-catch C-terminal amide linker (SCAL) that allowed mild cleavage conditions (I(2)/NaBH(4) and TFA...... to other tumor glycoforms by on-bead enzymatic glycosylation reactions with recombinant glycosyltransferases. Hence, we have developed a high-throughput flexible platform for rapid discovery of O-glycopeptide biomarkers and the method has applicability in other types of assays such as lectin...

  19. A High-Throughput SU-8Microfluidic Magnetic Bead Separator

    DEFF Research Database (Denmark)

    Bu, Minqiang; Christensen, T. B.; Smistrup, Kristian

    2007-01-01

    We present a novel microfluidic magnetic bead separator based on SU-8 fabrication technique for high through-put applications. The experimental results show that magnetic beads can be captured at an efficiency of 91 % and 54 % at flow rates of 1 mL/min and 4 mL/min, respectively. Integration...... of soft magnetic elements in the chip leads to a slightly higher capturing efficiency and a more uniform distribution of captured beads over the separation chamber than the system without soft magnetic elements....

  20. A two-channel detection method for autofluorescence correction and efficient on-bead screening of one-bead one-compound combinatorial libraries using the COPAS fluorescence activated bead sorting system

    International Nuclear Information System (INIS)

    Hintersteiner, Martin; Auer, Manfred

    2013-01-01

    One-bead one-compound combinatorial library beads exhibit varying levels of autofluorescence after solid phase combinatorial synthesis. Very often this causes significant problems for automated on-bead screening using TentaGel beads and fluorescently labeled target proteins. Herein, we present a method to overcome this limitation when fluorescence activated bead sorting is used as the screening method. We have equipped the COPAS bead sorting instrument with a high-speed profiling unit and developed a spectral autofluorescence correction method. The correction method is based on a simple algebraic operation using the fluorescence data from two detection channels and is applied on-the-fly in order to reliably identify hit beads by COPAS bead sorting. Our method provides a practical tool for the fast and efficient isolation of hit beads from one-bead one-compound library screens using either fluorescently labeled target proteins or biotinylated target proteins. This method makes hit bead identification easier and more reliable. It reduces false positives and eliminates the need for time-consuming pre-sorting of library beads in order to remove autofluorescent beads. (technical note)

  1. K Basin sludge/resin bead separation test report

    International Nuclear Information System (INIS)

    Squier, D.M.

    1998-01-01

    The K Basin sludge is an accumulation of fuel element corrosion products, organic and inorganic ion exchange materials, canister gasket materials, iron and aluminum corrosion products, sand, dirt and minor amounts of other organic material. The sludge will be collected and treated for storage and eventual disposal. This process will remove the large solid materials by a 1/4 inch screen. The screened material will be subjected to nitric acid in a chemical treatment process. The organic ion exchange resin beads produce undesirable chemical reactions with the nitric acid. The resin beads must be removed from the bulk material and treated by another process. An effective bead separation method must extract 95% of the resin bead mass without entraining more than 5% of the other sludge component mass. The test plan I-INF-2729, ''Organic Ion Exchange Resin Separation Methods Evaluation,'' proposed the evaluation of air lift, hydro cyclone, agitated slurry and elutriation resin bead separation methods. This follows the testing strategy outlined in section 4.1 of BNF-2574, ''Testing Strategy to Support the Development of K Basins Sludge Treatment Process''. Engineering study BNF-3128, ''Separation of Organic Ion Exchange Resins from Sludge,'' Rev. 0, focused the evaluation tests on a method that removed the fine sludge particles by a sieve and then extracted the beads by means of a elutriation column. Ninety-nine percent of the resin beads are larger than 125 microns and 98.5 percent are 300 microns and larger. Particles smaller than 125 microns make up the largest portion of sludge in the K Basins. Eliminating a large part of the sludge's non-bead component will reduce the quantity that is lifted with the resin beads in the elutriation column. Resin bead particle size distribution measurements are given in Appendix A The Engineering Testing Laboratory conducted measurements of a elutriation column's ability to extract resin beads from a sieved, non-radioactive sludge

  2. Characterizing and quantifying superparamagnetic magnetite particles in serpentinized mantle peridotite observed in continental ophiolite complexes.

    Science.gov (United States)

    Ortiz, E.; Vento, N. F. R.; Tominaga, M.; Beinlich, A.; Einsle, J. F.; Buisman, I.; Ringe, E.; Schrenk, M. O.; Cardace, D.

    2017-12-01

    Serpentinization of mantle peridotite has been recognized as one of the most important energy factories for the deep biosphere. To better evaluate the habitability of the deep biosphere, it is crucial to understand the link between in situ peridotite serpentinization processes and associated magnetite and hydrogen production. Previous efforts in correlating magnetite and hydrogen production during serpentinization processes are based primarily on laboratory experiments and numerical modeling, being challenged to include the contribution of superparamagnetic-sized magnetites (i.e., extremely fine-grained magnetite, petrographically observed as a "pepper flake" like texture in many natural serpentinized rock samples). To better estimate the abundance of superparamagnetic grains, we conducted frequency-dependent susceptibility magnetic measurements at the Institute of Rock Magnetism on naturally serpentinized rock samples from the Coast Range Ophiolite Microbial Observatory (CROMO) in California, USA and the Atlin Ophiolite (British Columbia). In addition, we conducted multiscale EDS phase mapping, BackScattered Electron (BSE) scanning, FIB-nanotomography and STEM-EELS to identify and quantify the superparamagnetic minerals that contribute to the measured magnetic susceptibility signals in our rock samples. Utilizing a multidisciplinary approach, we aim to improve the estimation of hydrogen production based on the abundance of magnetite, that includes the contribution of superparamagnetic particle size magnetite, to ultimately provide a more accurate estimation of bulk deep-biomass hosted by in situ serpentinization processes.

  3. Mössbauer studies of superparamagnetic ferrite nanoparticles for functional application

    International Nuclear Information System (INIS)

    Mažeika, K.; Jagminas, A.; Kurtinaitienė, M.

    2013-01-01

    Nanoparticles of CoFe 2 O 4 and MnFe 2 O 4 prepared for functional applications in nanomedicine were studied using Mössbauer spectrometry. Superparamagnetic properties of nanoparticles of different size and composition were compared applying collective excitations and multilevel models for the description of the Mössbauer spectra.

  4. Spin-lock MR enhances the detection sensitivity of superparamagnetic iron oxide particles

    NARCIS (Netherlands)

    Moonen, R.P.M.; van der Tol, P.; Hectors, S.J.C.G.; Starmans, L.W.E.; Nicolaij, K.; Strijkers, G.J.

    2015-01-01

    Purpose To evaluate spin-lock MR for detecting superparamagnetic iron oxides and compare the detection sensitivity of quantitative T1ρ with T2 imaging. Methods In vitro experiments were performed to investigate the influence of iron oxide particle size and composition on T1ρ. These comprise T1ρ and

  5. Spin-lock MR enhances the detection sensitivity of superparamagnetic iron oxide particles

    NARCIS (Netherlands)

    Moonen, Rik P. M.; van der Tol, Pieternel; Hectors, Stefanie J. C. G.; Starmans, Lucas W. E.; Nicolay, Klaas; Strijkers, Gustav J.

    2015-01-01

    To evaluate spin-lock MR for detecting superparamagnetic iron oxides and compare the detection sensitivity of quantitative T1ρ with T2 imaging. In vitro experiments were performed to investigate the influence of iron oxide particle size and composition on T1ρ . These comprise T1ρ and T2 measurements

  6. Oxidative stress response in neural stem cells exposed to different superparamagnetic iron oxide nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Pongrac, I. M.; Pavičić, I.; Milić, M.; Brkić Ahmed, L.; Babič, Michal; Horák, Daniel; Vinković Vrček, I.; Gajović, S.

    2016-01-01

    Roč. 11, 26 April (2016), s. 1701-1715 ISSN 1176-9114 R&D Projects: GA ČR(CZ) GC16-01128J EU Projects: European Commission(XE) 316120 - GLOWBRAIN Institutional support: RVO:61389013 Keywords : superparamagnetic iron oxide nanoparticles * biocompatibility * oxidative stress Subject RIV: CD - Macromolecular Chemistry

  7. On-Chip Magnetic Bead Manipulation and Detection Using a Magnetoresistive Sensor-Based Micro-Chip: Design Considerations and Experimental Characterization

    KAUST Repository

    Gooneratne, Chinthaka Pasan; Kodzius, Rimantas; Li, Fuquan; Foulds, Ian G.; Kosel, Jü rgen

    2016-01-01

    The remarkable advantages micro-chip platforms offer over cumbersome, time-consuming equipment currently in use for bio-analysis are well documented. In this research, a micro-chip that includes a unique magnetic actuator (MA) for the manipulation of superparamagnetic beads (SPBs), and a magnetoresistive sensor for the detection of SPBs is presented. A design methodology, which takes into account the magnetic volume of SPBs, diffusion and heat transfer phenomena, is presented with the aid of numerical analysis to optimize the parameters of the MA. The MA was employed as a magnetic flux generator and experimental analysis with commercially available COMPEL™ and Dynabeads® demonstrated the ability of the MA to precisely transport a small number of SPBs over long distances and concentrate SPBs to a sensing site for detection. Moreover, the velocities of COMPEL™ and Dynabead® SPBs were correlated to their magnetic volumes and were in good agreement with numerical model predictions. We found that 2.8 μm Dynabeads® travel faster, and can be attracted to a magnetic source from a longer distance, than 6.2 μm COMPEL™ beads at magnetic flux magnitudes of less than 10 mT. The micro-chip system could easily be integrated with electronic circuitry and microfluidic functions, paving the way for an on-chip biomolecule quantification device

  8. On-Chip Magnetic Bead Manipulation and Detection Using a Magnetoresistive Sensor-Based Micro-Chip: Design Considerations and Experimental Characterization

    KAUST Repository

    Gooneratne, Chinthaka Pasan

    2016-08-26

    The remarkable advantages micro-chip platforms offer over cumbersome, time-consuming equipment currently in use for bio-analysis are well documented. In this research, a micro-chip that includes a unique magnetic actuator (MA) for the manipulation of superparamagnetic beads (SPBs), and a magnetoresistive sensor for the detection of SPBs is presented. A design methodology, which takes into account the magnetic volume of SPBs, diffusion and heat transfer phenomena, is presented with the aid of numerical analysis to optimize the parameters of the MA. The MA was employed as a magnetic flux generator and experimental analysis with commercially available COMPEL™ and Dynabeads® demonstrated the ability of the MA to precisely transport a small number of SPBs over long distances and concentrate SPBs to a sensing site for detection. Moreover, the velocities of COMPEL™ and Dynabead® SPBs were correlated to their magnetic volumes and were in good agreement with numerical model predictions. We found that 2.8 μm Dynabeads® travel faster, and can be attracted to a magnetic source from a longer distance, than 6.2 μm COMPEL™ beads at magnetic flux magnitudes of less than 10 mT. The micro-chip system could easily be integrated with electronic circuitry and microfluidic functions, paving the way for an on-chip biomolecule quantification device

  9. On-Chip Magnetic Bead Manipulation and Detection Using a Magnetoresistive Sensor-Based Micro-Chip: Design Considerations and Experimental Characterization

    Directory of Open Access Journals (Sweden)

    Chinthaka P. Gooneratne

    2016-08-01

    Full Text Available The remarkable advantages micro-chip platforms offer over cumbersome, time-consuming equipment currently in use for bio-analysis are well documented. In this research, a micro-chip that includes a unique magnetic actuator (MA for the manipulation of superparamagnetic beads (SPBs, and a magnetoresistive sensor for the detection of SPBs is presented. A design methodology, which takes into account the magnetic volume of SPBs, diffusion and heat transfer phenomena, is presented with the aid of numerical analysis to optimize the parameters of the MA. The MA was employed as a magnetic flux generator and experimental analysis with commercially available COMPEL™ and Dynabeads® demonstrated the ability of the MA to precisely transport a small number of SPBs over long distances and concentrate SPBs to a sensing site for detection. Moreover, the velocities of COMPEL™ and Dynabead® SPBs were correlated to their magnetic volumes and were in good agreement with numerical model predictions. We found that 2.8 μm Dynabeads® travel faster, and can be attracted to a magnetic source from a longer distance, than 6.2 μm COMPEL™ beads at magnetic flux magnitudes of less than 10 mT. The micro-chip system could easily be integrated with electronic circuitry and microfluidic functions, paving the way for an on-chip biomolecule quantification device.

  10. In vitro transcription of a torsionally constrained template

    DEFF Research Database (Denmark)

    Bentin, Thomas; Nielsen, Peter E

    2002-01-01

    of torsionally constrained DNA by free RNAP. We asked whether or not a newly synthesized RNA chain would limit transcription elongation. For this purpose we developed a method to immobilize covalently closed circular DNA to streptavidin-coated beads via a peptide nucleic acid (PNA)-biotin conjugate in principle...

  11. On-chip Brownian relaxation measurements of magnetic nanobeads in the time domain

    DEFF Research Database (Denmark)

    Østerberg, Frederik Westergaard; Rizzi, Giovanni; Hansen, Mikkel Fougt

    2013-01-01

    the time and frequency domain methods on Brownian relaxation detection of clustering of streptavidin coated magnetic beads in the presence of different concentrations of biotin-conjugated bovine serum albumin and obtain comparable results. In the time domain, a measurement is carried out in less than 30 s...

  12. Efficient functionalization of poly(styrene) beads immobilized metal ...

    Indian Academy of Sciences (India)

    Three types of new bead-shaped heterogeneous nanoparticle (NP) catalysts were synthesized by sim- plified procedures .... and Ag+-doped titanium. Therefore, removal ..... References. 1. Storhoff J J, Elghanian R, Mucic R C, Mirkin C A and.

  13. An approach to implement virtual channels for flowing magnetic beads

    International Nuclear Information System (INIS)

    Tang, Shih-Hao; Chiang, Hung-Wei; Hsieh, Min-Chien; Chang, Yen-Di; Yeh, Po-Fan; Tsai, Jui-che; Shieh, Wung-Yang

    2014-01-01

    This work demonstrates the feasibility of a novel microfluidic system with virtual channels formed by ‘walls’ of magnetic fields, including collecting channels, transporting channels and function channels. The channels are defined by the nickel patterns. With its own ferromagnetism, nickel can be magnetized using an external magnetic field; the nickel structures then generate magnetic fields that can either guide or trap magnetic beads. A glass substrate is sandwiched between the liquid containing magnetic beads and the chip with nickel structures, preventing the liquid from directly contacting the nickel. In this work, collecting channels, transporting channels and function channels are displayed sequentially. In the collecting channel portion, channels with different shapes are compared. Next, in the transporting channel portion we demonstrate I-, S- and Y-shaped channels can steer magnetic beads smoothly. Finally, in the function channel portion, a switchable trapping channel implemented with a bistable mechanism performs the passing and blocking of a magnetic bead. (paper)

  14. Standard specification for beaded process glass pipe and fittings

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2002-01-01

    1.1 This specification covers chemically resistant, low expansion Type-I borosilicate glass, Class A, (see Specification E 438) used to manufacture beaded end flanged-glass pipe and fittings for pressure and vacuum applications.

  15. Influence of recycled polystyrene beads on cement paste properties

    Directory of Open Access Journals (Sweden)

    Maaroufi Maroua

    2018-01-01

    Full Text Available In order to keep up with the requirements of sustainable development, there is a growing interest towards reducing the energy consumption in the construction and rehabilitation of buildings and the promotion of recycling waste in building materials. The use of recycled polystyrene beads in cement-based materials composition constitutes a solution to improve the insulation in buildings. This allows also limiting landfill by reusing the polystyrene waste. The aim of this study is to compare some properties and performances of a cement paste containing polystyrene beads to a reference paste designed with only the same cement. An experimental campaign was conducted and the obtained results showed that adding recycled polystyrene beads to a cement paste improves its hygro-thermal properties. Further studies are however necessary to better understand the real role of the polystyrene beads in the heat and mass transfers.

  16. TiO₂ beads and TiO₂-chitosan beads for urease immobilization.

    Science.gov (United States)

    Ispirli Doğaç, Yasemin; Deveci, Ilyas; Teke, Mustafa; Mercimek, Bedrettin

    2014-09-01

    The aim of the present study is to synthesize TiO2 beads for urease immobilization. Two different strategies were used to immobilize the urease on TiO2 beads. In the first method (A), urease enzyme was immobilized onto TiO2 beads by adsorption and then crosslinking. In the second method (B), TiO2 beads were coated with chitosan-urease mixture. To determine optimum conditions of immobilization, different parameters were investigated. The parameters of optimization were initial enzyme concentration (0.5; 1; 1.5; 2mg/ml), alginate concentration (1; 2; 3%), glutaraldehyde concentration (1; 2; 3% v/v) and chitosan concentration (2; 3; 4 mg/ml). The optimum enzyme concentrations were determined as 1.5mg/ml for A and 1.0mg/ml for B. The other optimum conditions were found 2.0% (w/v) for alginate concentration (both A and B); 3.0mg/ml for chitosan concentration (B) and 2.0% (v/v) for glutaraldehyde concentration (A). The optimum temperature (20-60°C), optimum pH (3.0-10.0), kinetic parameters, thermal stability (4-70°C), pH stability (4.0-9.0), operational stability (0-230 min) and reusability (20 times) were investigated for characterization. The optimum temperatures were 30°C (A), 40°C (B) and 35°C (soluble). The temperature profiles of the immobilized ureases were spread over a large area. The optimum pH values for the soluble urease and immobilized urease prepared by using methods (A) and (B) were found to be 7.5, 7.0, 7.0, respectively. The thermal stabilities of immobilized enzyme sets were studied and they maintained 50% activity at 65°C. However, at this temperature free urease protected only 15% activity. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Sensitive detection of nucleic acids by PNA hybridization directed co-localization of fluorescent beads

    DEFF Research Database (Denmark)

    Shiraishi, Takehiko; Deborggraeve, Stijn; Büscher, Philippe

    2011-01-01

    )avidin-coated fluorescent beads, differing in size and color [green beads (1 µm) and red beads (5.9 µm)], thereby allowing distinct detection of each PNA probe by conventional fluorescence microscopy. These two PNA beads showed easily detectable co-localization when simultaneously hybridizing to a target nucleic acid...

  18. Ferrite bead effect on Class-D amplifier audio quality

    OpenAIRE

    Haddad , Kevin El; Mrad , Roberto; Morel , Florent; Pillonnet , Gael; Vollaire , Christian; Nagari , Angelo

    2014-01-01

    International audience; This paper studies the effect of ferrite beads on the audio quality of Class-D audio amplifiers. This latter is a switch-ing circuit which creates high frequency harmonics. Generally, a filter is used at the amplifier output for the sake of electro-magnetic compatibility (EMC). So often, in integrated solutions, this filter contains ferrite beads which are magnetic components and present nonlinear behavior. Time domain measurements and their equivalence in frequency do...

  19. Plasma membrane isolation using immobilized concanavalin A magnetic beads.

    Science.gov (United States)

    Lee, Yu-Chen; Srajer Gajdosik, Martina; Josic, Djuro; Lin, Sue-Hwa

    2012-01-01

    Isolation of highly purified plasma membranes is the key step in constructing the plasma membrane proteome. Traditional plasma membrane isolation method takes advantage of the differential density of organelles. While differential centrifugation methods are sufficient to enrich for plasma membranes, the procedure is lengthy and results in low recovery of the membrane fraction. Importantly, there is significant contamination of the plasma membranes with other organelles. The traditional agarose affinity matrix is suitable for isolating proteins but has limitation in separating organelles due to the density of agarose. Immobilization of affinity ligands to magnetic beads allows separation of affinity matrix from organelles through magnets and could be developed for the isolation of organelles. We have developed a simple method for isolating plasma membranes using lectin concanavalin A (ConA) magnetic beads. ConA is immobilized onto magnetic beads by binding biotinylated ConA to streptavidin magnetic beads. The ConA magnetic beads are used to bind glycosylated proteins present in the membranes. The bound membranes are solubilized from the magnetic beads with a detergent containing the competing sugar alpha methyl mannoside. In this study, we describe the procedure of isolating rat liver plasma membranes using sucrose density gradient centrifugation as described by Neville. We then further purify the membrane fraction by using ConA magnetic beads. After this purification step, main liver plasma membrane proteins, especially the highly glycosylated ones and proteins containing transmembrane domains could be identified by LC-ESI-MS/MS. While not described here, the magnetic bead method can also be used to isolate plasma membranes from cell lysates. This membrane purification method should expedite the cataloging of plasma membrane proteome.

  20. Preparation of Bio-beads and Their Atrazine Degradation Characteristics

    Institute of Scientific and Technical Information of China (English)

    BI Hai-tao; ZHANG Lan-ying; LIU Na; ZHU Bo-lin

    2011-01-01

    Screened atrazine-mineralizing bacterium-Pseudomonas W4 was embedded inside an improved PVAH3BO3 embedment matrix to make bio-beads to degrade atrazine. The atrazine degradation characteristics were studied. The preparation procedure of bio-beads was as follows: (1) preparing a mixture of 100, 12.5, 10, 1.5 and 1 g/L PVA, bentonite(Ca), activated carbon powder, sodium alginate and centrifuged Pseudomonas W4 bacterium, respectively; (2) the mixture was dropped into a gently stirred cross linker solution(pH=6.7) and cured at 10 ℃ for 24 h.The optimal atrazine degradation conditions by bio-beads were as follows: pH=7, the auxiliary carbon source was glucose, and the concentration of glucose was greater than 325 mg/L. The bio-beads demonstrated stronger tolerance ability than the free microorganism to the increase of PCBs, hydrogen ion and hydroxide ion. SEM images show the uniform distribution of the microorganism inside bio-beads and the porous cross-linked structure of bio-beads which provides excellent mass transfer capacity.

  1. Effects of agitation rate on aggregation during beads-to-beads subcultivation of microcarrier culture of human mesenchymal stem cells.

    Science.gov (United States)

    Takahashi, Iori; Sato, Keigo; Mera, Hisashi; Wakitani, Shigeyuki; Takagi, Mutsumi

    2017-06-01

    With the aim to utilize human mesenchymal stem cells (hMSCs) grown in large scale for regenerative medicine, effects of agitation rate on aggregation during beads-to-beads subcultivation of microcarrier culture of hMSCs were studied. hMSCs could attach and grew on surface-type microcarriers of Cytodex 1, whereas almost no cell elongation and growth were observed on porous type microcarriers of Cytopores. The percentages of aggregated Cytodex 1 microcarriers at an agitation rate of 60 and 90 rpm were lower than that at 30 rpm, which was the lowest agitation rate necessary for the suspension of Cytodex 1 microcarriers, and the cells grew fastest at 60 rpm. hMSC could be subcultivated on Cytodex 1 by the beads-to-beads method at both 30 and 60 rpm without trypsinization. However, agitation at 60 rpm resulted in a markedly lower percentage of aggregated microcarriers not only before but also after subcultivation. The percentages of CD90- and CD166-positive cells among cells grown on Cytodex 1 at 60 rpm (91.5 and 87.6 %) were comparable to those of cells grown in the pre-culture on dishes. In conclusion, hMSCs could be subcultivated on Cytodex 1 by beads-to-beads method maintaining the expressions of the cell surface antigens CD90 and CD166, while adjusting agitation rate could decrease the microcarrier aggregation.

  2. Gd3+ doped Mn-Zn soft ferrite nanoparticles: Superparamagnetism and its correlation with other physical properties

    Science.gov (United States)

    Thakur, Prashant; Sharma, Rohit; Sharma, Vineet; Barman, P. B.; Kumar, Manoj; Barman, Dipto; Katyal, S. C.; Sharma, Pankaj

    2017-06-01

    Superparamagnetic nanoparticles are very important in biomedicine due to their various applications like drug delivery, gene delivery in the body and also used for hyperthermia. In the present work, superparamagnetic nanoparticles of Mn0.5Zn0.5GdxFe2-xO4 (x = 0, 0.025, 0.050, 0.075, 0.1) ferrites have been prepared by co-precipitation method. Thorough characterizations (XRD, FTIR, FE-SEM, EDS, VSM and fluorescence spectroscopy) have proved the formation of cubical spinel superparamagnetic nanoparticles of soft ferrites. A cation distribution has been proposed for the determination of various important theoretical parameters for these samples. With the addition of Gd3+ nanoparticles have shown the superparamagnetism at room temperature confirmed by VSM analysis. Photoluminescence (PL) spectra shows a blue shift (for x = 0.025, 0.075) which may be due to quantum confinement.

  3. Enhanced bio-compatibility of ferrofluids of self-assembled superparamagnetic iron oxide-silica core-shell nanoparticles

    Digital Repository Service at National Institute of Oceanography (India)

    Narayanan, T.N.; Mary, A.P.R.; Swalih, P.K.A.; Kumar, D.S.; Makarov, D.; Albrecht, M.; Puthumana, J.; Anas, A.; Anantharaman, A.

    -interacting, monodispersed and hence the synthesis of such nanostructures has great relevance in the realm of nanoscience. Silica-coated superparamagnetic iron oxide nanoparticles based ferrofluids were prepared using polyethylene glycol as carrier fluid by employing a...

  4. Use of antibiotic beads to salvage infected breast implants.

    Science.gov (United States)

    Sherif, Rami D; Ingargiola, Michael; Sanati-Mehrizy, Paymon; Torina, Philip J; Harmaty, Marco A

    2017-10-01

    When an implant becomes infected, implant salvage is often performed where the implant is removed, capsulectomy is performed, and a new implant is inserted. The patient is discharged with a PICC line and 6-8 weeks of intravenous (IV) antibiotics. This method has variable success and subjects the patient to long-term systemic antibiotics. In the 1960s, the use of antibiotic-impregnated beads for the treatment of chronic osteomyelitis was described. These beads deliver antibiotic directly to the site of the infection, thereby eliminating the complications of systemic IV antibiotics. This study aimed to present a case series illustrating the use of STIMULAN calcium sulfate beads loaded with vancomycin and tobramycin to increase the rate of salvage of the infected implant and forgo IV antibiotics. A retrospective analysis was performed of patients who were treated at Mount Sinai Hospital for implant infection with salvage and antibiotic beads. Twelve patients were identified, 10 of whom had breast cancer. Comorbidities included hypertension, smoking, and immunocompromised status. Infections were noted anywhere from 5 days to 8 years postoperatively. Salvage was successful in 9 out of the 12 infected implants using antibiotic bead therapy without home IV antibiotics. The use of antibiotic beads is promising for salvaging infected breast implants without IV antibiotics. Seventy-five percent of the implants were successfully salvaged. Of the three patients who had unsalvageable implants, one was infected with antibiotic-resistant Rhodococcus that was refractory to bead therapy and one was noncompliant with postoperative instructions. Copyright © 2017 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

  5. Two Contrasting Failure Modes of Enteric Coated Beads.

    Science.gov (United States)

    Shi, Galen H; Dong, Xia; Lytle, Michelle; Kemp, Craig A J; Behme, Robert J; Hinds, Jeremy; Xiao, Zhicheng

    2018-04-09

    This study aimed to elucidate the mechanisms and kinetics of coating failure for enteric coated beads exposed to high-humidity conditions at different storage temperatures. Enteric coated beads were placed on high-humidity conditions (75 to 98% relative humidity (RH)) in the temperature range of 5 to 40°C. These stability samples of beads were tested for acid dissolution and water activity and also analyzed with SEM, X-ray CT, and DMA. Exposure of enteric coated beads to high humidity led to increased gastric release of drug which eventually failed the dissolution specification. SEM showed visible cracks on the surface of beads exposed to 5°C/high humidity and fusion of enteric beads into agglomerates at 40°C/high humidity. In a non-destructive time elapse study, X-ray CT demonstrated swelling of microcrystalline cellulose cores, crack initiation, and propagation through the API layer within days under 5°C/98% RH storage conditions and ultimately fracture through the enteric coating. DMA data showed a marked reduction in T g of the enteric coating materials after exposure to humidity. At 5°C/high humidity, the hygroscopic microcrystalline cellulose core absorbed moisture leading to core swelling and consequent fracture through the brittle API and enteric layers. At 40°C (high humidity) which is above the T g of the enteric polymer, enteric coated beads coalesced into agglomerates due to melt flow of the enteric coating. We believe it is the first report on two distinct failure models of enteric coated dosage forms.

  6. Confocal nanoscanning, bead picking (CONA): PickoScreen microscopes for automated and quantitative screening of one-bead one-compound libraries.

    Science.gov (United States)

    Hintersteiner, Martin; Buehler, Christof; Uhl, Volker; Schmied, Mario; Müller, Jürgen; Kottig, Karsten; Auer, Manfred

    2009-01-01

    Solid phase combinatorial chemistry provides fast and cost-effective access to large bead based libraries with compound numbers easily exceeding tens of thousands of compounds. Incubating one-bead one-compound library beads with fluorescently labeled target proteins and identifying and isolating the beads which contain a bound target protein, potentially represents one of the most powerful generic primary high throughput screening formats. On-bead screening (OBS) based on this detection principle can be carried out with limited automation. Often hit bead detection, i.e. recognizing beads with a fluorescently labeled protein bound to the compound on the bead, relies on eye-inspection under a wide-field microscope. Using low resolution detection techniques, the identification of hit beads and their ranking is limited by a low fluorescence signal intensity and varying levels of the library beads' autofluorescence. To exploit the full potential of an OBS process, reliable methods for both automated quantitative detection of hit beads and their subsequent isolation are needed. In a joint collaborative effort with Evotec Technologies (now Perkin-Elmer Cellular Technologies Germany GmbH), we have built two confocal bead scanner and picker platforms PS02 and a high-speed variant PS04 dedicated to automated high resolution OBS. The PS0X instruments combine fully automated confocal large area scanning of a bead monolayer at the bottom of standard MTP plates with semiautomated isolation of individual hit beads via hydraulic-driven picker capillaries. The quantification of fluorescence intensities with high spatial resolution in the equatorial plane of each bead allows for a reliable discrimination between entirely bright autofluorescent beads and real hit beads which exhibit an increased fluorescence signal at the outer few micrometers of the bead. The achieved screening speed of up to 200,000 bead assayed in less than 7 h and the picking time of approximately 1 bead

  7. Processes Leading to Beaded Channels Formation in Central Yakutia

    Science.gov (United States)

    Tarbeeva, A. M.; Lebedeva, L.; Efremov, V. S.; Krylenko, I. V.; Surkov, V. V.

    2017-12-01

    Beaded channels, consisting of deepened and widened pools and connecting narrow runs, are common fluvial forms in permafrost regions. Recent studies have shown that beaded channels are very important for connecting alluvial rivers with headwater lakes allowing fish passage and foraging habitats, as well as regulating river runoff. Beaded channels are known as typical thermokarst landforms; however, there is no evidence of their origin and formative processes. Geomorphological analyzes of beaded channels have been completed in several permafrost regions including field observations of Shestakovka River in Central Yakutia. The study aims to recognize the modern exogenic processes and formative mechanisms of beaded river channels. We show that beaded channel of Shestakovka River form in the perennially frozen sand with low ice content, leading us to hypothesize that thermokarst is not the main process of formation. Due to the significant volume of water, the pools don't freeze over entirely during winters, even under harsh climatic conditions. As a result, lenses of pressurized water remain under surface ice underlain by perennially thawed sediments. The presence of thawed sediments under the pools and frozen sediments under the runs leads to uneven thermoerosion of the riverbed during floods, providing the beaded form of the channel. In addition, freezing of pools during winter leads to pressure increasing under ice cover and formation of ice mounds, which crack several times during winter leading to disturbance of riverbanks. Many 1st to 3rd order streams have a specific transitional meandering-to-beaded form resembling the shape of unconfined meandering rivers, but consisting of pools and runs. However, such channels exhibit no evidences of present-day erosion of concave banks and sediment accumulation at the convex banks as typically being observed in normally meandering rivers. Such forms of channels indicates that their formation occurred by the greater channel

  8. Recent advances in synthesis and surface modification of superparamagnetic iron oxide nanoparticles with silica

    International Nuclear Information System (INIS)

    Sodipo, Bashiru Kayode; Aziz, Azlan Abdul

    2016-01-01

    Research on synthesis of superparamagnetic iron oxide nanoparticles (SPION) and its surface modification for biomedical applications is of intense interest. Due to superparamagnetic property of SPION, the nanoparticles have large magnetic susceptibility, single magnetic domain and controllable magnetic behaviour. However, owing to easy agglomeration of SPION, surface modification of the magnetic particles with biocompatible materials such as silica nanoparticle has gained much attention in the last decade. In this review, we present recent advances in synthesis of SPION and various routes of producing silica coated SPION. - Highlights: • We present recent advances in synthesis of SPION and various routes of producing silica coated SPION • The synthetic routes of producing SPION can be classified into three: physical, chemical and biological methods. • The chemical method is the most cited method of producing SPION and it sub-classified into liquid and gas phase. • The techniques of producing silica coated SPION is grouped into seeded and non-seeded methods.

  9. Imaging pathobiology of carotid atherosclerosis with ultrasmall superparamagnetic particles of iron oxide: an update.

    Science.gov (United States)

    Sadat, Umar; Usman, Ammara; Gillard, Jonathan H

    2017-07-01

    To provide brief overview of the developments regarding use of ultrasmall superparamagnetic particles of iron oxide in imaging pathobiology of carotid atherosclerosis. MRI is a promising technique capable of providing morphological and functional information about atheromatous plaques. MRI using iron oxide particles, called ultrasmall superparamagnetic iron oxide (USPIO) particles, allows detection of macrophages in atherosclerotic tissue. Ferumoxytol has emerged as a new USPIO agent, which has an excellent safety profile. Based on the macrophage-selective properties of ferumoxytol, there is increasing number of recent reports suggesting its effectiveness to detect pathological inflammation. USPIO particles allow magnetic resonance detection of macrophages in atherosclerotic tissue. Ferumoxytol has emerged as a new USPIO agent, with an excellent safety profile. This has the potential to be used for MRI of the pathobiology of atherosclerosis.

  10. Recent advances in synthesis and surface modification of superparamagnetic iron oxide nanoparticles with silica

    Energy Technology Data Exchange (ETDEWEB)

    Sodipo, Bashiru Kayode, E-mail: bashirsodipo@gmail.com [School of Physics, Universiti Sains Malaysia, 11800 Pulau Pinang (Malaysia); Nano-Biotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 Pulau Pinang (Malaysia); Aziz, Azlan Abdul [School of Physics, Universiti Sains Malaysia, 11800 Pulau Pinang (Malaysia); Nano-Biotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 Pulau Pinang (Malaysia)

    2016-10-15

    Research on synthesis of superparamagnetic iron oxide nanoparticles (SPION) and its surface modification for biomedical applications is of intense interest. Due to superparamagnetic property of SPION, the nanoparticles have large magnetic susceptibility, single magnetic domain and controllable magnetic behaviour. However, owing to easy agglomeration of SPION, surface modification of the magnetic particles with biocompatible materials such as silica nanoparticle has gained much attention in the last decade. In this review, we present recent advances in synthesis of SPION and various routes of producing silica coated SPION. - Highlights: • We present recent advances in synthesis of SPION and various routes of producing silica coated SPION • The synthetic routes of producing SPION can be classified into three: physical, chemical and biological methods. • The chemical method is the most cited method of producing SPION and it sub-classified into liquid and gas phase. • The techniques of producing silica coated SPION is grouped into seeded and non-seeded methods.

  11. Superparamagnetic and ferrimagnetic behavior of nanocrystalline ZnO(MnO)

    Science.gov (United States)

    Kuryliszyn-Kudelska, I.; Dobrowolski, W.; Arciszewska, M.; Romčević, N.; Romčević, M.; Hadžić, B.; Sibera, D.; Narkiewicz, U.

    2018-04-01

    We have studied the magnetic properties of nanocrystals of ZnO:MnO prepared by traditional wet chemistry method. The detailed structural and morphological characterization was performed. The results of systematic measurements of AC magnetic susceptibility as a function of temperature and frequency as well as DC magnetization are reported. We observed two different types of magnetic behavior depending on the concentration doping. For samples with low nominal content (up to 30 wt% of MnO), superparamagnetic behavior was observed. We attribute the observed superparamagnetism to the presence of nanosized ZnMnO3 phase. For nanocrystals doped above nominal 60 wt% of MnO ferrimagnetism was detected with TC at around 42 K. This magnetic behavior we assign to the presence of nanosized Mn3O4 phase.

  12. A functionalized superparamagnetic iron oxide colloid as a receptor directed MR contrast agent

    International Nuclear Information System (INIS)

    Josephson, L.; Groman, E.V.; Menz, E.; Lewis, J.M.; Bengele, H.

    1990-01-01

    We have synthesized a surface functionalized superparamagnetic iron oxide colloid whose clearance from the vascular compartment was inhibited by asialofetuin but not fetuin. Unlike other particulate or colloidal magnetic resonance (MR) contrast agents, the agent of the current communication is not withdrawn from the vascular compartment by cells of the macrophage-monocyte phagocytic system, as indicated by its selective increase in hepatic relaxation rates. Because of this we refer to this colloid as a hepatic selective (HS) MR contrast agent. At 20 mumol Fe/kg the HS MR agent darkened MR images of liver. The HS MR agent exhibited no acute toxicity when injected into rats at 1800 mumol Fe/kg. Based on these observations, surface functionalized superparamagnetic iron oxide colloids may be the basis of MR contrast agents internalized by receptor mediated endocytosis generally, and by the asialoglycoprotein receptor in particular

  13. Environmentally Compatible Synthesis of Superparamagnetic Magnetite (Fe3O4 Nanoparticles with Prehydrolysate from Corn Stover

    Directory of Open Access Journals (Sweden)

    Chunming Zheng

    2013-12-01

    Full Text Available An environmentally compatible and size-controlled method has been employed for synthesis of superparamagnetic magnetite nanoparticles with prehydrolysate from corn stover. Various characterizations involving X-ray diffraction (XRD, standard and high-resolution transmission electron microscopy (TEM and HRTEM, selected area electron diffraction (SAED, and thermogravimetric analysis (TGA have integrally confirmed the formation of magnetite nanoparticles with homogeneous morphology and the formation mechanism of magnetite only from ferric precursor. Organic materials in the prehydrolysate act as a bifunctional agent: (1 a reducing agent to reduce ferric ions to prepare magnetite with the coexistence of ferric and ferrous ions; and (2 a coating agent to prevent particle growth and agglomeration and to promote the formation of nanoscale and superparamagnetic magnetite. The size of the magnetite nanoparticles can be easily controlled by tailoring the reducing sugar concentration, reaction time, or hydrothermal temperature.

  14. Splenic red pulp macrophages are intrinsically superparamagnetic and contaminate magnetic cell isolates.

    Science.gov (United States)

    Franken, Lars; Klein, Marika; Spasova, Marina; Elsukova, Anna; Wiedwald, Ulf; Welz, Meike; Knolle, Percy; Farle, Michael; Limmer, Andreas; Kurts, Christian

    2015-08-11

    A main function of splenic red pulp macrophages is the degradation of damaged or aged erythrocytes. Here we show that these macrophages accumulate ferrimagnetic iron oxides that render them intrinsically superparamagnetic. Consequently, these cells routinely contaminate splenic cell isolates obtained with the use of MCS, a technique that has been widely used in immunological research for decades. These contaminations can profoundly alter experimental results. In mice deficient for the transcription factor SpiC, which lack red pulp macrophages, liver Kupffer cells take over the task of erythrocyte degradation and become superparamagnetic. We describe a simple additional magnetic separation step that avoids this problem and substantially improves purity of magnetic cell isolates from the spleen.

  15. Multiple functionalities of Ni nanoparticles embedded in carboxymethyl guar gum polymer: catalytic activity and superparamagnetism

    Science.gov (United States)

    Sardar, Debasmita; Sengupta, Manideepa; Bordoloi, Ankur; Ahmed, Md. A.; Neogi, S. K.; Bandyopadhyay, Sudipta; Jain, Ruchi; Gopinath, Chinnakonda S.; Bala, Tanushree

    2017-05-01

    Composites comprising of metallic nanoparticles in polymer matrices have allured significant importance due to multifunctionalities. Here a simple protocol has been described to embed Ni nanoparticles in carboxymethyl guar gum (CMGG) polymer. The composite formation helps in the stabilization of Ni nanoparticles which are otherwise prone towards aerial oxidation. Further the nanoparticles retain their superparamagnetic nature and catalytic capacity. Ni-Polymer composite catalyses the reduction of 4-Nitrophenol to 4-Aminophenol very efficiently in presence of NaBH4, attaining a complete conversion under some experimental conditions. Ni-Polymer composite is well characterized using UV-vis spectroscopy, FTIR, XPS, powder XRD, TGA, SEM and TEM. A detailed magnetic measurement using superconducting quantum interference device-vibrating sample magnetometer (SQUID-VSM) reveals superparamagnetic behaviour of the composite.

  16. Magnetic composites based on hybrid spheres of aluminum oxide and superparamagnetic nanoparticles of iron oxides

    International Nuclear Information System (INIS)

    Braga, Tiago P.; Vasconcelos, Igor F.; Sasaki, Jose M.; Fabris, J.D.; Oliveira, Diana Q.L. de; Valentini, Antoninho

    2010-01-01

    Materials containing hybrid spheres of aluminum oxide and superparamagnetic nanoparticles of iron oxides were obtained from a chemical precursor prepared by admixing chitosan and iron and aluminum hydroxides. The oxides were first characterized with scanning electron microscopy, X-ray diffraction, and Moessbauer spectroscopy. Scanning electron microscopy micrographs showed the size distribution of the resulting spheres to be highly homogeneous. The occurrence of nano-composites containing aluminum oxides and iron oxides was confirmed from powder X-ray diffraction patterns; except for the sample with no aluminum, the superparamagnetic relaxation due to iron oxide particles were observed from Moessbauer spectra obtained at 298 and 110 K; the onset six line-spectrum collected at 20 K indicates a magnetic ordering related to the blocking relaxation effect for significant portion of small spheres in the sample with a molar ratio Al:Fe of 2:1.

  17. Transarterial chemoembolization with drug-eluting beads in hepatocellular carcinoma

    Science.gov (United States)

    Nam, Hee Chul; Jang, Bohyun; Song, Myeong Jun

    2016-01-01

    Transarterial chemoembolization (TACE) is a widely used standard treatment for patients with hepatocellular carcinoma (HCC) who are not suitable candidates for curative treatments. The rationale for TACE is that intra-arterial chemotherapy using lipiodol and chemotherapeutic agents, followed by selective vascular embolization, results in a strong cytotoxic effect as well as ischemia (conventional TACE). Recently, drug-eluting beads (DC Beads®) have been developed for transcatheter treatment of HCC to deliver higher doses of the chemotherapeutic agent and to prolong contact time with the tumor. DC Beads® can actively sequester doxorubicin hydrochloride from solution and release it in a controlled sustained fashion. Treatment with DC Beads® substantially reduced the amount of chemotherapeutic agent that reached the systemic circulation compared with conventional, lipiodol-based regimens, significantly reducing drug-related adverse events. In this article, we describe the treatment response, survival, and safety of TACE used with drug-eluting beads for the treatment of HCC and discuss future therapeutic possibilities. PMID:27833376

  18. Surface imprinted beads for the recognition of human serum albumin.

    Science.gov (United States)

    Bonini, Francesca; Piletsky, Sergey; Turner, Anthony P F; Speghini, Adolfo; Bossi, Alessandra

    2007-04-15

    The synthesis of poly-aminophenylboronic acid (ABPA) imprinted beads for the recognition of the protein human serum albumin (HSA) is reported. In order to create homogeneous recognition sites, covalent immobilisation of the template HSA was exploited. The resulting imprinted beads were selective for HSA. The indirect imprinting factor (IF) calculated from supernatant was 1.6 and the direct IF, evaluated from the protein recovered from the beads, was 1.9. The binding capacity was 1.4 mg/g, which is comparable to commercially available affinity materials. The specificity of the HSA recognition was evaluated with competitive experiments, indicating a molar ratio 4.5/1 of competitor was necessary to displace half of the bound HSA. The recognition and binding of the imprinted beads was also tested with a complex sample, human serum and targeted removal of HSA without a loss of the other protein components was demonstrated. The easy preparation protocol of derivatised beads and a good protein recognition properties make the approach an attractive solution to analytical and bio-analytical problems in the field of biotechnology.

  19. Removal of Uranium from Aqueous Solution by Alginate Beads

    Directory of Open Access Journals (Sweden)

    Jing Yu

    2017-04-01

    Full Text Available The adsorption of uranium (VI by calcium alginate beads was examined by batch experiments. The effects of environmental conditions on U (VI adsorption were studied, including contact time, pH, initial concentration of U (VI, and temperature. The alginate beads were characterized by using scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. Fourier transform infrared spectra indicated that hydroxyl and alkoxy groups are present at the surface of the beads. The experimental results showed that the adsorption of U (VI by alginate beads was strongly dependent on pH, the adsorption increased at pH 3∼7, then decreased at pH 7∼9. The adsorption reached equilibrium within 2 minutes. The adsorption kinetics of U (VI onto alginate beads can be described by a pseudo first-order kinetic model. The adsorption isotherm can be described by the Redlich-Peterson model, and the maximum adsorption capacity was 237.15 mg/g. The sorption process is spontaneous and has an exothermic reaction.

  20. Removal of uranium from aqueous solution by aliginate beads

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Jing; Wang, Jian Long [Collaborative Innovation Center for Advanced Nuclear Energy Technology, INET, Tsinghua University, Beijing (China); Jiang, Yizhou [Northwest Institute of Nuclear Technology, Xian (China)

    2017-04-15

    The adsorption of uranium (VI) by calcium alginate beads was examined by batch experiments. The effects of environmental conditions on U (VI) adsorption were studied, including contact time, pH, initial concentration of U (VI), and temperature. The alginate beads were characterized by using scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. Fourier transform infrared spectra indicated that hydroxyl and alkoxy groups are present at the surface of the beads. The experimental results showed that the adsorption of U (VI) by alginate beads was strongly dependent on pH, the adsorption increased at pH 3∼7, then decreased at pH 7∼9. The adsorption reached equilibrium within 2 minutes. The adsorption kinetics of U (VI) onto alginate beads can be described by a pseudo first-order kinetic model. The adsorption isotherm can be described by the Redlich-Peterson model, and the maximum adsorption capacity was 237.15 mg/g. The sorption process is spontaneous and has an exothermic reaction.

  1. Controlled antiseptic release by alginate polymer films and beads.

    Science.gov (United States)

    Liakos, Ioannis; Rizzello, Loris; Bayer, Ilker S; Pompa, Pier Paolo; Cingolani, Roberto; Athanassiou, Athanassia

    2013-01-30

    Biodegradable polymeric materials based on blending aqueous dispersions of natural polymer sodium alginate (NaAlg) and povidone iodine (PVPI) complex, which allow controlled antiseptic release, are presented. The developed materials are either free standing NaAlg films or Ca(2+)-cross-linked alginate beads, which properly combined with PVPI demonstrate antibacterial and antifungal activity, suitable for therapeutic applications, such as wound dressing. Glycerol was used as the plasticizing agent. Film morphology was studied by optical and atomic force microscopy. It was found that PVPI complex forms well dispersed circular micro-domains within the NaAlg matrix. The beads were fabricated by drop-wise immersion of NaAlg/PVPI/glycerol solutions into aqueous calcium chloride solutions to form calcium alginate beads encapsulating PVPI solution (CaAlg/PVPI). Controlled release of PVPI was possible when the composite films and beads were brought into direct contact with water or with moist media. Bactericidal and fungicidal properties of the materials were tested against Escherichia coli bacteria and Candida albicans fungi. The results indicated very efficient antibacterial and antifungal activity within 48 h. Controlled release of PVPI into open wounds is highly desired in clinical applications to avoid toxic doses of iodine absorption by the wound. A wide variety of applications are envisioned such as external and internal wound dressings with controlled antiseptic release, hygienic and protective packaging films for medical devices, and polymer beads as water disinfectants. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. Fluorescent detection of C-reactive protein using polyamide beads

    Science.gov (United States)

    Jagadeesh, Shreesha; Chen, Lu; Aitchison, Stewart

    2016-03-01

    Bacterial infection causes Sepsis which is one of the leading cause of mortality in hospitals. This infection can be quantified from blood plasma using C - reactive protein (CRP). A quick diagnosis at the patient's location through Point-of- Care (POC) testing could give doctors the confidence to prescribe antibiotics. In this paper, the development and testing of a bead-based procedure for CRP quantification is described. The size of the beads enable them to be trapped in wells without the need for magnetic methods of immobilization. Large (1.5 mm diameter) Polyamide nylon beads were used as the substrate for capturing CRP from pure analyte samples. The beads captured CRP either directly through adsorption or indirectly by having specific capture antibodies on their surface. Both methods used fluorescent imaging techniques to quantify the protein. The amount of CRP needed to give a sufficient fluorescent signal through direct capture method was found suitable for identifying bacterial causes of infection. Similarly, viral infections could be quantified by the more sensitive indirect capture method. This bead-based assay can be potentially integrated as a disposable cartridge in a POC device due to its passive nature and the small quantities needed.

  3. Quantum interference oscillations of the superparamagnetic blocking in an Fe8 molecular nanomagnet

    OpenAIRE

    Burzurí, E.; Luis, F.; Montero, O.; Barbara, B.; Ballou, R.; Maegawa, S.

    2013-01-01

    We show that the dynamic magnetic susceptibility and the superparamagnetic blocking temperature of an Fe8 single molecule magnet oscillate as a function of the magnetic field Hx applied along its hard magnetic axis. These oscillations are associated with quantum interferences, tuned by Hx, between different spin tunneling paths linking two excited magnetic states. The oscillation period is determined by the quantum mixing between the ground S=10 and excited multiplets. These experiments enabl...

  4. Whole tissue AC susceptibility after superparamagnetic iron oxide contrast agent administration in a rat model

    International Nuclear Information System (INIS)

    Lazaro, Francisco Jose; Gutierrez, Lucia; Rosa Abadia, Ana; Soledad Romero, Maria; Lopez, Antonio; Jesus Munoz, Maria

    2007-01-01

    A magnetic AC susceptibility characterisation of rat tissues after intravenous administration of superparamagnetic iron oxide (Endorem ( R)), at the same dose as established for Magnetic Resonance Imaging (MRI) contrast enhancement in humans, has been carried out. The measurements reveal the presence of the contrast agent as well as that of physiological ferritin in liver and spleen while no traces have been magnetically detected in heart and kidney. This preliminary work opens suggestive possibilities for future biodistribution studies of any type of magnetic carriers

  5. Intrinsically superparamagnetic Fe-hydroxyapatite nanoparticles positively influence osteoblast-like cell behaviour

    Science.gov (United States)

    2012-01-01

    Background Superparamagnetic nanoparticles (MNPs) have been progressively explored for their potential in biomedical applications and in particular as a contrast agent for diagnostic imaging, for magnetic drug delivery and more recently for tissue engineering applications. Considering the importance of having safe MNPs for such applications, and the essential role of iron in bone remodelling, this study developed and analysed novel biocompatible and bioreabsorbable superparamagnetic nanoparticles, that avoid the use of poorly tolerated magnetite based nanoparticles, for bone tissue engineering applications. Results MNPs were obtained by doping hydroxyapatite (HA) with Fe ions, by directly substituting Fe2+ and Fe3+ into the HA structure yielding superparamagnetic bioactive phase. In the current study, we have investigated the effects of increasing concentrations (2000 μg/ml; 1000 μg/ml; 500 μg/ml; 200 μg/ml) of FeHA MNPs in vitro using Saos-2 human osteoblast-like cells cultured for 1, 3 and 7 days with and without the exposure to a static magnetic field of 320 mT. Results demonstrated not only a comparable osteoblast viability and morphology, but increased in cell proliferation, when compared to a commercially available Ha nanoparticles, even with the highest dose used. Furthermore, FeHA MNPs exposure to the static magnetic field resulted in a significant increase in cell proliferation throughout the experimental period, and higher osteoblast activity. In vivo preliminary results demonstrated good biocompatibility of FeHA superparamagnetic material four weeks after implantation into a critical size lesion of the rabbit condyle. Conclusions The results of the current study suggest that these novel FeHA MNPs may be particularly relevant for strategies of bone tissue regeneration and open new perspectives for the application of a static magnetic field in a clinical setting of bone replacement, either for diagnostic imaging or magnetic drug delivery

  6. A method for synthesis and functionalization of ultrasmall superparamagnetic covalent carriers based on maghemite and dextran

    International Nuclear Information System (INIS)

    Mornet, Stephane; Portier, Josik; Duguet, Etienne

    2005-01-01

    A new generation of susceptibility contrast agents for MRI and based on maghemite cores covalently bonded to dextran stabilizing macromolecules was investigated. The multistep preparation of these versatile ultrasmall superparamagnetic iron oxides (VUSPIO) consisted of colloidal maghemite synthesis, surface modification by aminopropylsilane groups, and coupling of partially oxidized dextran via Schiff's bases and secondary amine bonds. The dextran corona might be easily derivatized, e.g. by PEGylation

  7. Monodisperse superparamagnetic nanoparticles by thermolysis of Fe(III) oleate and mandelate complexes

    Czech Academy of Sciences Publication Activity Database

    Patsula, Vitalii; Petrovský, Eduard; Kovářová, Jana; Konefal, Rafal; Horák, Daniel

    2014-01-01

    Roč. 292, č. 9 (2014), s. 2097-2110 ISSN 0303-402X R&D Projects: GA ČR GAP206/12/0381; GA MŠk 7E12053 EU Projects: European Commission(XE) 246513 - NADINE Institutional support: RVO:61389013 ; RVO:67985530 Keywords : superparamagnetic * nanoparticles * iron oxide Subject RIV: CD - Macromolecular Chemistry; DE - Earth Magnetism, Geodesy, Geography (GFU-E) Impact factor: 1.865, year: 2014

  8. A facile method to prepare superparamagnetic iron oxide and hydrophobic drug-encapsulated biodegradable polyurethane nanoparticles

    OpenAIRE

    Cheng,Kuo-Wei; Hsu,Shan-hui

    2017-01-01

    Kuo-Wei Cheng, Shan-hui Hsu Institute of Polymer Science and Engineering, College of Engineering, National Taiwan University, Taipei, Taiwan, Republic of China Abstract: Superparamagnetic iron oxide nanoparticles (SPIO NPs) have a wide range of biomedical applications such as in magnetic resonance imaging, targeting, and hyperthermia therapy. Aggregation of SPIO NPs can occur because of the hydrophobic surface and high surface energy of SPIO NPs. Here, we developed a facile method to encaps...

  9. Tissue Plasminogen Activator Binding to Superparamagnetic Iron Oxide Nanoparticle—Covalent Versus Adsorptive Approach

    Science.gov (United States)

    Friedrich, Ralf P.; Zaloga, Jan; Schreiber, Eveline; Tóth, Ildikó Y.; Tombácz, Etelka; Lyer, Stefan; Alexiou, Christoph

    2016-06-01

    Functionalized superparamagnetic iron oxide nanoparticles are frequently used to develop vehicles for drug delivery, hyperthermia, and photodynamic therapy and as tools used for magnetic separation and purification of proteins or for biomolecular imaging. Depending on the application, there are various possible covalent and non-covalent approaches for the functionalization of particles, each of them shows different advantages and disadvantages for drug release and activity at the desired location.

  10. Processing of superparamagnetic iron contrast agent ferucarbotran in transplanted pancreatic islets

    Czech Academy of Sciences Publication Activity Database

    Zacharovová, K.; Berková, Z.; Jirák, D.; Herynek, V.; Vancová, Marie; Dovolilová, E.; Saudek, F.

    2012-01-01

    Roč. 7, č. 6 (2012), s. 485-493 ISSN 1555-4309 Institutional research plan: CEZ:AV0Z60220518 Keywords : magnetic resonance imaging * pancreatic islets * transplantation * superparamagnetic iron oxide nanoparticles * ferucarbotran * β cells * diabetes * immunohistochemistry * transmission electron microscopy Subject RIV: CE - Biochemistry Impact factor: 2.872, year: 2012 http://onlinelibrary.wiley.com/doi/10.1002/cmmi.1477/full

  11. Spectroscopic and magnetic studies of highly dispersible superparamagnetic silica coated magnetite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Tadyszak, Krzysztof [NanoBioMedical Centre, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznań (Poland); Institute of Molecular Physics Polish Academy of Sciences, ul. Mariana Smo.luchowskiego 17, 60-179 Poznań (Poland); Kertmen, Ahmet, E-mail: ahmet.kertmen@pg.gda.pl [Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk (Poland); Coy, Emerson [NanoBioMedical Centre, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznań (Poland); Andruszkiewicz, Ryszard; Milewski, Sławomir [Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk (Poland); Kardava, Irakli; Scheibe, Błażej; Jurga, Stefan [NanoBioMedical Centre, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznań (Poland); Chybczyńska, Katarzyna, E-mail: katarzyna.chybczynska@ifmpan.poznan.pl [Institute of Molecular Physics Polish Academy of Sciences, ul. Mariana Smo.luchowskiego 17, 60-179 Poznań (Poland)

    2017-07-01

    Highlights: • Superparamagnetic core-shell nanoparticles of Fe{sub 2}O{sub 3}@Silica were obtained. • Magnetic response was studied by DC, AC magnetometry and EPR spectroscopy. • Nanoparticles show magnetite structure with a well-defined Verwey transition. • Samples show no inter particle magnetic interactions or agglomeration. - Abstract: Superparamagnetic behavior in aqueously well dispersible magnetite core-shell Fe{sub 3}O{sub 4}@SiO{sub 2} nanoparticles is presented. The magnetic properties of core-shell nanoparticles were measured with use of the DC, AC magnetometry and EPR spectroscopy. Particles where characterized by HR-TEM and Raman spectroscopy, showing a crystalline magnetic core of 11.5 ± 0.12 nm and an amorphous silica shell of 22 ± 1.5 nm in thickness. The DC, AC magnetic measurements confirmed the superparamagnetic nature of nanoparticles, additionally the EPR studies performed at much higher frequency than DC, AC magnetometry (9 GHz) have confirmed the paramagnetic nature of the nanoparticles. Our results show the excellent magnetic behavior of the particles with a clear magnetite structure, which are desirable properties for environmental remediation and biomedical applications.

  12. Treatment of Aqueous Bromate by Superparamagnetic BiOCl-Mediated Advanced Reduction Process

    Directory of Open Access Journals (Sweden)

    Xiaowei Liu

    2017-05-01

    Full Text Available Bromate ( BrO 3 − contamination in drinking water is a growing concern. Advanced reduction processes (ARPs are reportedly promising in relieving this concern. In this work, UV/superparamagnetic BiOCl (BiOCl loaded onto superparamagnetic hydroxyapatite assisted with small molecule carboxylic acid (formate, citrate, and acetate, a carboxyl anion radical ( CO 2 • − -based ARP, was proposed to eliminate aqueous BrO 3 − . Formate and citrate were found to be ideal CO 2 • − precursor, and the latter was found to be safe for practical use. BrO 3 − (10 μg·L−1, WHO guideline for drinking water can be completely degraded within 3 min under oxygen-free conditions. In this process, BrO 3 − degradation was realized by the reduction of CO 2 • − (major role and formyloxyl radical (minor role in bulk solution. The formation mechanism of radicals and the transformation pathway of BrO 3 − were proposed based on data on electron paramagnetic resonance monitoring, competitive kinetics, and degradation product analysis. The process provided a sustainable decontamination performance (<5% deterioration for 10 cycles and appeared to be more resistant to common electron acceptors (O2, NO 3 − , and Fe3+ than hydrated electron based-ARPs. Phosphate based-superparamagnetic hydroxyapatite, used to support BiOCl in this work, was believed to be applicable for resolving the recycling problem of other metal-containing catalyst.

  13. MRI in acute cerebral ischaemia: perfusion imaging with superparamagnetic iron oxide in a rat model

    International Nuclear Information System (INIS)

    Forsting, M.; Reith, W.; Doerfler, A.; Kummer, R. von; Hacke, W.; Sartor, K.

    1994-01-01

    An imaging technique capable of detecting ischaemic cerebral injury at an early stage could improve diagnosis in acute or transient cerebral ischaemia. We compared the ability of superparamagnetically contrast-enhanced MRI and conventional T2-weighted MRI to detect ischaemic injury early after unilateral occlusion of the middle cerebral artery in 12 male Wistar rats. Permanent vessel occlusion was achieved by a transvascular approach, which has the advantage of not requiring a craniectom. At 45-60 min after the procedure, the animals had conventional T2-weighted MRI before and after administration of a superparamagnetic contrast agent (iron oxide particles). Unenhanced images were normal in all animals. After administration of iron oxide particles, the presumed ischaemic area was clearly visible, as relatively increased signal, in all animals; this high signal area corresponded to the area of ischaemic brain infarction seen on histological studies. Our results suggest that superparamagnetic iron particles may significantly reduce the interval between an ischaemic insult and the appearance of parenchymal changes on MRI. (orig./UWA)

  14. SEPARATION OF CELL POPULATIONS BY SUPER-PARAMAGNETIC PARTICLES WITH CONTROLLED SURFACE FUNCTIONALITY

    Directory of Open Access Journals (Sweden)

    Lootsik M. D.

    2014-02-01

    Full Text Available The recognition and isolation of specific mammalian cells by the biocompatible polymer coated super-paramagnetic particles with determined surface functionality were studied. The method of synthesis of nanoscaled particles on a core of iron III oxide (Fe2O3, magemit coated with a polymer shell containing reactive oligoperoxide groups for attachment of ligands is described. By using the developed superparamagnetic particles functionalized with peanut agglutinin (PNA we have separated the sub-populations of PNA+ and PNA– cells from ascites of murine Nemeth-Kellner lymphoma. In another type of experiment, the particles were opsonized with proteins of the fetal calf serum that improved biocompatibility of the particles and their ingestion by cultivated murine macrophages J774.2. Macrophages loaded with the particles were effeciently separated from the particles free cells by using the magnet. Thus, the developed surface functionalized superparamagnetic particles showed to be a versatile tool for cell separation independent on the mode of particles’ binding with cell surface or their engulfment by the targeted cells.

  15. Thermal treatment to enhance saturation magnetization of superparamagnetic Ni nanoparticles while maintaining low coercive force

    Science.gov (United States)

    Ishizaki, Toshitaka; Yatsugi, Kenichi; Akedo, Kunio

    2018-05-01

    Superparamagnetic nanoparticles capped by insulators have the potential to decrease eddy current and hysteresis losses. However, the saturation magnetization ( M s) decreases significantly with decreasing the particle size. In this study, superparamagnetic Ni nanoparticles having the mean size of 11.6 ± 1.8 nm were synthesized from the reduction of Ni(II) acetylacetonate in oleylamine with the addition of trioctylphosphine, indicating the coercive force ( H c) less than 1 Oe. Thermal treatments of the Ni nanoparticles were investigated as a method to enhance the M s. The results indicated that the M s was enhanced by an increase of the Ni mass ratio with increasing thermal treatment temperature. However, the decomposition behavior of the capping layers indicated that their alkyl chains actively decomposed at temperatures above 523 K to form Ni3P via reaction between Ni and P, resulting in particle growth with a significant increase in the H c. Therefore, the optimal temperature was determined to be 473 K, which increased the Ni ratio without formation of Ni3P while maintaining particle sizes with superparamagnetic properties. Further, the M s could be improved by 22% (relative to the as-synthesized Ni nanoparticles) after thermal treatment at 473 K while maintaining the H c to be less than 1 Oe.

  16. Conjugating folate on superparamagnetic Fe3O4@Au nanoparticles using click chemistry

    International Nuclear Information System (INIS)

    Shen, Xiaofang; Ge, Zhaoqiang; Pang, Yuehong

    2015-01-01

    Gold-coated magnetic core@shell nanoparticles, which exhibit magneto-optical properties, not only enhance the chemical stability of core and biocompatibility of surface, but also provide a combination of multimodal imaging and therapeutics. The conjugation of these tiny nanoparticles with specific biomolecules allows researchers to target the desired location. In this paper, superparamagnetic Fe 3 O 4 @Au nanoparticles were synthesized and functionalized with the azide group on the surface by formation of self-assembled monolayers. Folate (FA) molecules, non-immunogenic target ligands for cancer cells, are conjugated with alkyne and then immobilized on the azide-terminated Fe 3 O 4 @Au nanoparticles through copper(I)-catalyzed azide-alkyne cycloaddition (click reaction). Myelogenous leukemia K562 cells were used as a folate receptor (FR) model, which can be targeted and extracted by magnetic field after interaction with the Fe 3 O 4 @Au–FA nanoparticles. - Graphical abstract: Self-assembled azide-terminated group on superparamagnetic Fe 3 O 4 @Au nanoparticles followed by click reaction with alkyne-functionalized folate, allowing the nanoparticles target folate receptor of cancer cells. - Highlights: • Azidoundecanethiol was coated on the superparamagnetic Fe 3 O 4 @Au nanoparticles by forming self-assembled monolayers. • Alkyne-terminated folate was synthesized from a reaction between the amine and the carboxylic acid. • Conjugation of Fe 3 O 4 @Au nanoparticles with folate was made by copper-catalyzed azide-alkyne cycloaddition click chemistry

  17. Multiple functionalities of Ni nanoparticles embedded in carboxymethyl guar gum polymer: catalytic activity and superparamagnetism

    Energy Technology Data Exchange (ETDEWEB)

    Sardar, Debasmita [Department of Chemistry, University of Calcutta, 92 A.P.C. Road, Kolkata 700009 (India); Sengupta, Manideepa; Bordoloi, Ankur [Nano Catalysis, Catalytic Conversion and Process Division, CSIR—Indian Institute of Petroleum (IIP), Mohkampur, Dehradun 248005 (India); Ahmed, Md. A.; Neogi, S.K.; Bandyopadhyay, Sudipta [Department of Physics, University of Calcutta, 92 A.P.C. Road, Kolkata 700009 (India); Jain, Ruchi; Gopinath, Chinnakonda S. [Catalysis Division and Center of Excellence on Surface Science, CSIR—National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411 008 (India); Bala, Tanushree, E-mail: tanushreebala@gmail.com [Department of Chemistry, University of Calcutta, 92 A.P.C. Road, Kolkata 700009 (India)

    2017-05-31

    Highlights: • Ni nanoparticles were synthesized in polymer to form Ni-Polymer composite. • Ni nanoparticles retain their superparamagnetism in the composite. • Ni-Polymer composites showed catalytic activity. - Abstract: Composites comprising of metallic nanoparticles in polymer matrices have allured significant importance due to multifunctionalities. Here a simple protocol has been described to embed Ni nanoparticles in carboxymethyl guar gum (CMGG) polymer. The composite formation helps in the stabilization of Ni nanoparticles which are otherwise prone towards aerial oxidation. Further the nanoparticles retain their superparamagnetic nature and catalytic capacity. Ni-Polymer composite catalyses the reduction of 4-Nitrophenol to 4-Aminophenol very efficiently in presence of NaBH{sub 4}, attaining a complete conversion under some experimental conditions. Ni-Polymer composite is well characterized using UV–vis spectroscopy, FTIR, XPS, powder XRD, TGA, SEM and TEM. A detailed magnetic measurement using superconducting quantum interference device-vibrating sample magnetometer (SQUID-VSM) reveals superparamagnetic behaviour of the composite.

  18. A Pneumatic Actuated Microfluidic Beads-Trapping Device

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Guocheng; Cai, Ziliang; Wang, Jun; Wang, Wanjun; Lin, Yuehe

    2011-08-20

    The development of a polydimethylsiloxane (PDMS) microfluidic microbeads trapping device is reported in this paper. Besides fluid channels, the proposed device includes a pneumatic control chamber and a beads-trapping chamber with a filter array structure. The pneumatic flow control chamber and the beads-trapping chamber are vertically stacked and separated by a thin membrane. By adjusting the pressure in the pneumatic control chamber, the membrane can either be pushed against the filter array to set the device in trapping mode or be released to set the device in releasing mode. In this paper, a computational fluid dynamics simulation was conducted to optimize the geometry design of the filter array structure; the device fabrication was also carried out. The prototype device was tested and the preliminary experimental results showed that it can be used as a beads-trapping unit for various biochemistry and analytical chemistry applications, especially for flow injection analysis systems.

  19. Bead-based screening in chemical biology and drug discovery

    DEFF Research Database (Denmark)

    Komnatnyy, Vitaly V.; Nielsen, Thomas Eiland; Qvortrup, Katrine

    2018-01-01

    libraries for early drug discovery. Among the various library forms, the one-bead-one-compound (OBOC) library, where each bead carries many copies of a single compound, holds the greatest potential for the rapid identification of novel hits against emerging drug targets. However, this potential has not yet...... been fully realized due to a number of technical obstacles. In this feature article, we review the progress that has been made towards bead-based library screening and applications to the discovery of bioactive compounds. We identify the key challenges of this approach and highlight key steps needed......High-throughput screening is an important component of the drug discovery process. The screening of libraries containing hundreds of thousands of compounds requires assays amanable to miniaturisation and automization. Combinatorial chemistry holds a unique promise to deliver structural diverse...

  20. The dispersion of fine chitosan particles by beads-milling

    Science.gov (United States)

    Rochima, Emma; Utami, Safira; Hamdani, Herman; Azhary, Sundoro Yoga; Praseptiangga, Danar; Joni, I. Made; Panatarani, Camellia

    2018-02-01

    This research aimed to produce fine chitosan particles from a crab shell waste by beads-milling method by two different concentration of PEG as dispersing agent (150 and 300 wt. %). The characterization was performed to obtain the size and size distribution, the characteristics of functional groups and the degree of deacetylation. The results showed that the chitosan fine particles was obtained with a milling time 120 minutes with the best concentration of PEG 400 150 wt. %. The average particle size of the as-prepared suspension is 584 nm after addition of acetic acid solution (1%, v/v). Beads milling process did not change the glucosamine and N-acetylglucosamine content on chitosan structure which is indicated by degree of deacetylation higher than 70%. It was concluded that beads milling process can be applied to prepare chitosan fineparticles by proper adjustment in the milling time, pH and dosage of dispersing agent.

  1. Development of multifunctional chitosan beads for fluoride removal

    Energy Technology Data Exchange (ETDEWEB)

    Viswanathan, Natrayasamy [Department of Chemistry, Gandhigram Rural University, Gandhigram 624 302, Tamilnadu (India); Sairam Sundaram, C. [Department of Science and Humanities, Karaikal Polytechnic College, Karaikal 609 609, Puducherry (India); Meenakshi, S., E-mail: drs_meena@rediffmail.com [Department of Chemistry, Gandhigram Rural University, Gandhigram 624 302, Tamilnadu (India)

    2009-08-15

    Chitosan beads (CB) which have negligible defluoridation capacity (DC) have been chemically modified by introducing multifunctional groups, viz., NH{sub 3}{sup +} and COOH groups by means of protonation and carboxylation in order to utilize both amine and hydroxyl groups for fluoride removal. The protonated cum carboxylated chitosan beads (PCCB) showed a maximum DC of 1800 mg F{sup -}/kg whereas raw chitosan beads displayed only 52 mg F{sup -}/kg. Sorption process was found to be independent of pH and slightly influenced in the presence of other common anions. The fluoride sorption on modified forms was reasonably explained by Freundlich and Langmuir isotherms. The sorbents were characterised by FTIR and SEM with EDAX analysis. The sorption process follows pseudo-second-order and intraparticle diffusion kinetic models. The suitability of PCCB has been tested with field sample collected from a nearby fluoride endemic area.

  2. The Surface Imprinted Polystyrene Beads Prepared via Emulsion Templates

    Institute of Scientific and Technical Information of China (English)

    Guo Xiang CHENG; Guang Ling PEI; Ling Gang ZENG; Li Yong ZHANG; Chao LIU

    2004-01-01

    In this paper, the surface imprinted cross-linked polystyrene beads were prepared via suspension polymerization with styrene (St), divinylbezene (DVB), polyvinyl alcohol (PVA1788), the mixture of Span 85 and xylene or the mixture of Span 85 and paraffin as monomer, cross-linking agent, dispersion stabilizer and templates, respectively. The results indicate that there are dense cavities on the surface of beads, and the diameter and density of cavity are related with the composition and amount of emulsion template. The forming mechanism of cavity from thermodynamics and dynamics was proposed.

  3. Corrosion of ancient glass beads found in Southern Thailand

    International Nuclear Information System (INIS)

    Won-in, K; Thongkam, Y; Intarasiri, S; Kamwanna, T; Dararutana, P

    2012-01-01

    Glass has been used as ornaments and decorations in Thailand for several hundred years. The archaeological resources suggested that the ancient glass beads excavated in southern Thailand were made more than 1300 years ago. Initial findings revealed that there were number of difference in shade between the glass beads of difference colors. Energy dispersive X-ray spectrometer (EDS) system attached with scanning electron microscope (SEM) and particle-induced X-ray emission spectroscopy (PIXE) were firstly used to study the surface corrosion of the samples. SEM micrographs showed more corroded and flaked microstructure. These were contributed to the interaction of both the ground water and its dissolved chemical compounds.

  4. Residual gentamicin-release from antibiotic-loaded polymethylmethacrylate beads after 5 years of implantation

    NARCIS (Netherlands)

    Neut, D; van de Belt, H; van Horn, [No Value; van der Mei, HC; Busscher, HJ

    In infected joint arthroplasty, high local levels of antibiotics are achieved through temporary implantation of non-biodegradable gentamicin-loaded polymethylmethacrylate beads. Despite their antibiotic release, these beads act as a biomaterial surface to which bacteria preferentially adhere, grow

  5. Exploring Traditional Glass Bead Making Techniques in Jewellery ...

    African Journals Online (AJOL)

    Exploring traditional glass bead making techniques in jewellery in some prominent areas in Ghana is a means to exposing the area for metal and ceramic artists and other related fields of discipline such as aesthetics and criticism to complement their form of ... Keywords: livelihood, vitreous, glass bottles, furnace, threading ...

  6. Glass bead transformation method for gram-positive bacteria

    OpenAIRE

    Rattanachaikunsopon, Pongsak; Phumkhachorn, Parichat

    2009-01-01

    A simple, inexpensive and reproducible transformation method was developed for Gram-positive bacteria. It was based on agitation of bacterial protoplasts with glass beads in the presence of DNA and polyethylene glycol. By using this method, introduction of pGK12 into protoplasts of several strains of Gram-positive bacteria was achieved.

  7. Collection Development: From Beads to Bangles (Jewelry Making)

    Science.gov (United States)

    Hanrahan, Katie

    2010-01-01

    Jewelry making began exploding as a hobby about ten years ago, largely because the flush economy gave individuals more leisure time and disposable income. Jewelry classes, bead stores, and special events have multiplied like craft shows at Christmas time. While the recent economic downturn has slowed the growth of the hobby, it is still as popular…

  8. Evaluation of double drop beads pavement edge lines.

    Science.gov (United States)

    2009-08-01

    This report presents an evaluation of Double Drop Bead (DDB) edge lines used on ALDOT-maintained highways. It compares DDB to three other pavement marking types in terms of service lives, life-cycle costs, and both dry-night retroreflectivity and wet...

  9. Removal of organic dyes by magnetic alginate beads.

    Science.gov (United States)

    Rocher, Vincent; Siaugue, Jean-Michel; Cabuil, Valérie; Bee, Agnès

    2008-02-01

    This study deals with the development of a clean and safe process for water pollution remediation. We have synthesized a magnetic adsorbent in order to develop a solid-phase extraction process assisted by a magnetic field. To follow an 'ecoconception' approach, magnetic beads containing magnetic nanoparticles and activated carbon are prepared with a biopolymer extracted from algae, sodium alginate. The use of renewable bioresources of low cost and those disposable in large amount allows the development of a product with a low impact on the environment. The adsorption properties of activated carbon and magnetic properties of iron oxide nanoparticles are combined to produce an interesting magnetic composite. Synthesis and characterization of the magnetic beads have been reported. Their adsorption capacity was investigated by measuring the removal of two dyes (methylene blue and methyl orange) of different charges from aqueous solutions. The efficiency of the beads has been compared with that of non-encapsulated activated carbon. The effects of initial dye concentration, pH and calcium content of the beads have been studied. Adsorption kinetics experiments have been carried out and the data have been well fitted by a pseudo-second-order equation.

  10. StoryBeads: Preserving indigenous knowledge through tangible interaction design

    CSIR Research Space (South Africa)

    Reitsma, L

    2013-09-01

    Full Text Available in technology adoption. The study resulted in a recording device that fits the target group’s oral tradition and is based on a concept in which oral stories are recorded and associated with tangible beads that can be incorporated into traditional beadwork...

  11. Continuous removal and recovery of lead by alginate beads, free ...

    African Journals Online (AJOL)

    This study examines the possibility of using Chlorella vulgaris cells in repeated lead adsorption/desorption cycles. Alginate beads and immobilized with algal cells were more effective and suitable than free cells. Consistently high lead removal (>90%) and recovery (about 100%) were achieved. Lead adsorption was mainly ...

  12. 485 assessment of the problems of manual automobile tyre bead

    African Journals Online (AJOL)

    eobe

    rim bead bond must be broken to carry out repairs on a failed automobile tyre. ... engine will not be transformed into the motion of the vehicle. It provides the only point of contact between ..... Popular Mechanic 162 (6): 62. http://books.google.

  13. Low-cost commercial glass beads as dosimeters in radiotherapy

    International Nuclear Information System (INIS)

    Jafari, S.M.; Bradley, D.A.; Gouldstone, C.A.; Sharpe, P.H.G.; Alalawi, A.; Jordan, T.J.; Clark, C.H.; Nisbet, A.; Spyrou, N.M.

    2014-01-01

    Recent developments in advanced radiotherapy techniques using small field photon beams, require small detectors to determine the delivered dose in steep dose gradient fields. Commercially available glass jewellery beads exhibit thermoluminescent properties and have the potential to be used as dosimeters in radiotherapy due to their small size ( 60 Co gamma rays over doses ranging from 1 to 2500 cGy. A thermoluminescence (TL) system and an electron paramagnetic resonance (EPR) system were employed for read out. Both the TL and EPR studies demonstrated a radiation-induced signal, the sensitivity of which varied with bead colour. White coloured beads proved to be the most sensitive for both systems. The smallest and therefore least sensitive bead sizes allowed measurement of doses of 1 cGy using the TL system while that for the EPR system was approximately 1000 cGy. The fading rate was found to be 10% 30 days after irradiation with both readout systems. The dose response is linear with measured dose over the dose range 1 to 2500 cGy, with an R 2 correlation coefficient of greater than 0.999. The batch-to-batch reproducibility of a set of dosimeters after a single irradiation was found to be 3% (1 SD). The reproducibility of individual dosimeters was found to be 1.7%. No measurable angular dependence was found (results agreed within 1%). Dose rate response was found to agree within 1% for dose rates of 100 to 600 cGy/min. These results demonstrate the potential use of glass beads as TL dosimeters over the dose range commonly applied in radiotherapy. - Highlights: • We examined the dosimetric properties of a low cost commercially produced glass seed beads. • Glass beads are available in small size of 1–3 mm, suitable for dosimetry of small radiation fields. • The results demonstrate a mean reproducibility of 0.23% (2 SD), batch homogeneity of within 5%. • Dose response was linear over wide dose range tested for 1 cGy to kGy. • Improved fading effect of 10

  14. Gd3+ doped Mn-Zn soft ferrite nanoparticles: Superparamagnetism and its correlation with other physical properties

    International Nuclear Information System (INIS)

    Thakur, Prashant; Sharma, Rohit; Sharma, Vineet; Barman, P.B.; Kumar, Manoj; Barman, Dipto; Katyal, S.C.; Sharma, Pankaj

    2017-01-01

    Highlights: • Superparamagnetic nanoparticles of Gd doped Mn-Zn spinel ferrites synthesized by co-precipitation. • XRD and FTIR studies justify the formation of cubical spinel structure. • Maximum saturation magnetization and magnetic moment at x = 0.025. • PL spectra shows blue shift for x = 0.025, 0.075 and may be attributed to quantum confinement. - Abstract: Superparamagnetic nanoparticles are very important in biomedicine due to their various applications like drug delivery, gene delivery in the body and also used for hyperthermia. In the present work, superparamagnetic nanoparticles of Mn 0.5 Zn 0.5 Gd x Fe 2-x O 4 (x = 0, 0.025, 0.050, 0.075, 0.1) ferrites have been prepared by co-precipitation method. Thorough characterizations (XRD, FTIR, FE-SEM, EDS, VSM and fluorescence spectroscopy) have proved the formation of cubical spinel superparamagnetic nanoparticles of soft ferrites. A cation distribution has been proposed for the determination of various important theoretical parameters for these samples. With the addition of Gd 3+ nanoparticles have shown the superparamagnetism at room temperature confirmed by VSM analysis. Photoluminescence (PL) spectra shows a blue shift (for x = 0.025, 0.075) which may be due to quantum confinement.

  15. Gd{sup 3+} doped Mn-Zn soft ferrite nanoparticles: Superparamagnetism and its correlation with other physical properties

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Prashant; Sharma, Rohit; Sharma, Vineet; Barman, P.B. [Department of Physics & Materials Science, Jaypee University of Information Technology, Waknaghat, Solan, Himachal Pradesh 173234 (India); Kumar, Manoj [Department of Physics & Materials Science, Jaypee Institute of Information Technology, Noida 201307 (India); Barman, Dipto [Gwangju Institute of Science & Technology, Gwangju (Korea, Republic of); Department of Computer Science & Engineering, Jaypee University of Information Technology, Waknaghat, Solan, Himachap Pradesh 173234 (India); Katyal, S.C. [Department of Physics & Materials Science, Jaypee Institute of Information Technology, Noida 201307 (India); Sharma, Pankaj, E-mail: pankaj.sharma@juit.ac.in [Department of Physics & Materials Science, Jaypee University of Information Technology, Waknaghat, Solan, Himachal Pradesh 173234 (India)

    2017-06-15

    Highlights: • Superparamagnetic nanoparticles of Gd doped Mn-Zn spinel ferrites synthesized by co-precipitation. • XRD and FTIR studies justify the formation of cubical spinel structure. • Maximum saturation magnetization and magnetic moment at x = 0.025. • PL spectra shows blue shift for x = 0.025, 0.075 and may be attributed to quantum confinement. - Abstract: Superparamagnetic nanoparticles are very important in biomedicine due to their various applications like drug delivery, gene delivery in the body and also used for hyperthermia. In the present work, superparamagnetic nanoparticles of Mn{sub 0.5}Zn{sub 0.5}Gd{sub x}Fe{sub 2-x}O{sub 4} (x = 0, 0.025, 0.050, 0.075, 0.1) ferrites have been prepared by co-precipitation method. Thorough characterizations (XRD, FTIR, FE-SEM, EDS, VSM and fluorescence spectroscopy) have proved the formation of cubical spinel superparamagnetic nanoparticles of soft ferrites. A cation distribution has been proposed for the determination of various important theoretical parameters for these samples. With the addition of Gd{sup 3+} nanoparticles have shown the superparamagnetism at room temperature confirmed by VSM analysis. Photoluminescence (PL) spectra shows a blue shift (for x = 0.025, 0.075) which may be due to quantum confinement.

  16. Evaluation of umbilical cord mesenchymal stem cells labeling with superparamagnetic iron oxide nanoparticles coated with dextran and complexed with Poly-L-Lysine

    International Nuclear Information System (INIS)

    Sibov, Tatiana Tais; Mamani, Javier Bustamante; Pavon, Lorena Favaro; Cardenas, Walter Humberto; Gamarra, Lionel Fernel; Miyaki, Liza Aya Mabuchi; Marti, Luciana Cavalheiro; Sardinha, Luiz Roberto; Oliveira, Daniela Mara de

    2012-01-01

    Objective: The objective of this study was to evaluate the effect of the labeling of umbilical cord vein derived mesenchymal stem cells with superparamagnetic iron oxide nanoparticles coated with dextran and complexed to a non-viral transfector agent transfector poly-L-lysine. Methods: The labeling of mesenchymal stem cells was performed using the superparamagnetic iron oxide nanoparticles/dextran complexed and not complexed to poly-L-lysine. Superparamagnetic iron oxide nanoparticles/dextran was incubated with poly-L-lysine in an ultrasonic sonicator at 37 deg C for 10 minutes for complex formation superparamagnetic iron oxide nanoparticles/dextran/poly-L-lysine by electrostatic interaction. Then, the mesenchymal stem cells were incubated overnight with the complex superparamagnetic iron oxide nanoparticles/dextran/poly-L-lysine and superparamagnetic iron oxide nanoparticles/dextran. After the incubation period the mesenchymal stem cells were evaluated by internalization of the complex superparamagnetic iron oxide nanoparticles/dextran/polyL-lysine and superparamagnetic iron oxide nanoparticles/dextran by Prussian Blue stain. Cellular viability of labeled mesenchymal stem cells was evaluated by cellular proliferation assay using 5,6-carboxyfluorescein-succinimidyl ester method and apoptosis detection by Annexin V- Propidium Iodide assay. Results: mesenchymal stem cells labeled with superparamagnetic iron oxide nanoparticles/ dextran without poly-L-lysine not internalized efficiently the superparamagnetic iron oxide nanoparticles due to its low presence detected within cells. Mesenchymal stem cells labeled with the complex superparamagnetic iron oxide nanoparticles/dextran/polyL-lysine efficiently internalized the superparamagnetic iron oxide nanoparticles due to greater presence in the cells interior. The viability and apoptosis assays demonstrated that the mesenchymal stem cells labeled and not labeled respectively with the superparamagnetic iron oxide

  17. 49 CFR 173.221 - Polymeric beads, expandable and Plastic molding compound.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Polymeric beads, expandable and Plastic molding... Than Class 1 and Class 7 § 173.221 Polymeric beads, expandable and Plastic molding compound. (a) Non-bulk shipments of Polymeric beads (or granules), expandable, evolving flammable vapor and Plastic...

  18. Ionically crosslinked alginate–carboxymethyl cellulose beads for the delivery of protein therapeutics

    International Nuclear Information System (INIS)

    Kim, Min Sup; Park, Sang Jun; Gu, Bon Kang; Kim, Chun-Ho

    2012-01-01

    Highlights: ► We prepared Fe 3+ crosslinked alginate–carboxymethyl cellulose (AC) beads. ► Different surface and inner morphology of AC beads were observed on volume of CMC. ► AC beads showed minimum swelling degree in acidic condition. ► Protein release from AC beads was to control in gastrointestinal condition. - Abstract: We developed Fe 3+ -crosslinked alginate–carboxymethyl cellulose (AC) beads in various volume ratios by dropping an AC solution into a ferric chloride solution to form protein therapeutic carrier beads. Scanning electron microscopy revealed that the roughness and pore size of the crosslinked beads increased with the volume ratio of the carboxymethyl cellulose. Fourier transform-infrared analysis revealed the formation of a three-dimensional bonding structure between the anionic polymeric chains of AC and the Fe 3+ ions. The degree of swelling and the release profile of albumin from the beads were investigated under simulated gastrointestinal conditions (pH 1.2, 4.5, and 7.4). The Fe 3+ -crosslinked AC beads displayed different degrees of swelling and albumin release for the various AC volume ratios and under various pH conditions. An in vitro release test was used to monitor the controlled release of albumin from the AC beads under simulated gastrointestinal conditions over 24 h. The Fe 3+ -crosslinked AC beads protected and controlled the release of protein, demonstrating that such beads present a promising protein therapeutic carrier for the oral delivery.

  19. Flow Cytometry-Based Bead-Binding Assay for Measuring Receptor Ligand Specificity

    NARCIS (Netherlands)

    Sprokholt, Joris K.; Hertoghs, Nina; Geijtenbeek, Teunis B. H.

    2016-01-01

    In this chapter we describe a fluorescent bead-binding assay, which is an efficient and feasible method to measure interaction between ligands and receptors on cells. In principle, any ligand can be coated on fluorescent beads either directly or via antibodies. Binding between ligand-coated beads

  20. Magnetization of large polystyrene peptide beads for capturing and expanding cancer cells

    International Nuclear Information System (INIS)

    Marik, Jan; Lau, D.H.; Song Aimin; Wang Xiaobing; Liu Ruiwu; Lam, K.S.

    2003-01-01

    A method is described for preparation of large magnetic polystyrene beads coupled with peptide ligands for surface receptors of lung cancer cells. We have demonstrated the feasibility of using these magnetic peptide beads for capturing and enriching lung cancer cells spiked into blood. These magnetic peptide beads potentially can be used to efficiently isolate cancer cells from body fluids

  1. DTDGA impregnated XAD-16 beads for separation and recovery of palladium from acidic wastes

    International Nuclear Information System (INIS)

    Singh, Krishan Kant; Kanagare, Anant B.; Bairwa, K.K.; Manmohan Kumar; Bajaj, Parma N.; Ruhela, Ritesh; Singh, Ajoy K.; Hubli, Rajendra C.

    2014-01-01

    In the present study DTDGA extractant impregnated XAD16 polymeric beads (DTDGA- XAD16) were synthesized by wet chemical method and the beads were characterized by various techniques viz. FT-IR, Optical microscopy, SEM and TGA. The DTDGA-XAD 16 beads were evaluated for separation and recovery of palladium from high level waste solutions (HLW)

  2. Process and device for fabrication of ice beads and application to abrasive blasting with ice beads for surface treatments

    International Nuclear Information System (INIS)

    Barnier, M.; Manificat, A.; Perroud, P.

    1989-01-01

    A device is described for cleaning and decontamination by abrasive blasting with ice beads. It comprises a water injector, with many holes, at the top of a column feeded with cold gas where solidification of water droplets begins, solidification is completed in a cooling liquids, ice is extracted by a screw and pushed to the projection nozzle with cold gas [fr

  3. A facile method to prepare superparamagnetic iron oxide and hydrophobic drug-encapsulated biodegradable polyurethane nanoparticles

    Directory of Open Access Journals (Sweden)

    Cheng K

    2017-03-01

    Full Text Available Kuo-Wei Cheng, Shan-hui Hsu Institute of Polymer Science and Engineering, College of Engineering, National Taiwan University, Taipei, Taiwan, Republic of China Abstract: Superparamagnetic iron oxide nanoparticles (SPIO NPs have a wide range of biomedical applications such as in magnetic resonance imaging, targeting, and hyperthermia therapy. Aggregation of SPIO NPs can occur because of the hydrophobic surface and high surface energy of SPIO NPs. Here, we developed a facile method to encapsulate SPIO NPs in amphiphilic biodegradable polymer. Anionic biodegradable polyurethane nanoparticles (PU NPs with ~35 nm size and different chemistry were prepared by waterborne processes. SPIO NPs were synthesized by chemical co-precipitation. SPIO NPs were then added to the aqueous dispersion of PU NPs, followed by application of high-frequency (~20 kHz ultrasonic vibration for 3 min. This method rendered SPIO-PU hybrid NPs (size ~110 nm suspended in water. SPIO-PU hybrid NPs contained ~50–60 wt% SPIO and retained the superparamagnetic property (evaluated by a magnetometer as well as high contrast in magnetic resonance imaging. SPIO-PU NPs also showed the ability to provide cell hyperthermic treatment. Using the same ultrasonic method, hydrophobic drug (Vitamin K3 [VK3] or (9-(methylaminomethylanthracene [MAMA] could also be encapsulated in PU NPs. The VK3-PU or MAMA-PU hybrid NPs had ~35 nm size and different release profiles for PUs with different chemistry. The encapsulation efficiency for VK3 and MAMA was high (~95% without burst release. The encapsulation mechanism may be attributed to the low glass transition temperature (Tg and good mechanical compliance of PU NPs. The new encapsulation method involving waterborne biodegradable PU NPs is simple, rapid, and effective to produce multimodular NP carriers. Keywords: superparamagnetic iron oxide, polyurethane, drug release, hybrid nanoparticles

  4. Quantum Interference Oscillations of the Superparamagnetic Blocking in an Fe8 Molecular Nanomagnet

    Science.gov (United States)

    Burzurí, E.; Luis, F.; Montero, O.; Barbara, B.; Ballou, R.; Maegawa, S.

    2013-08-01

    We show that the dynamic magnetic susceptibility and the superparamagnetic blocking temperature of an Fe8 single molecule magnet oscillate as a function of the magnetic field Hx applied along its hard magnetic axis. These oscillations are associated with quantum interferences, tuned by Hx, between different spin tunneling paths linking two excited magnetic states. The oscillation period is determined by the quantum mixing between the ground S=10 and excited multiplets. These experiments enable us to quantify such mixing. We find that the weight of excited multiplets in the magnetic ground state of Fe8 amounts to approximately 11.6%.

  5. Toxicity of superparamagnetic iron oxide nanoparticles: Research strategies and implications for nanomedicine

    International Nuclear Information System (INIS)

    Li Lei; Jiang Ling-Ling; Zeng Yun; Liu Gang

    2013-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) are one of the most versatile and safe nanoparticles in a wide variety of biomedical applications. In the past decades, considerable efforts have been made to investigate the potential adverse biological effects and safety issues associated with SPIONs, which is essential for the development of next-generation SPIONs and for continued progress in translational research. In this mini review, we summarize recent developments in toxicity studies on SPIONs, focusing on the relationship between the physicochemical properties of SPIONs and their induced toxic biological responses for a better toxicological understanding of SPIONs. (topical review - magnetism, magnetic materials, and interdisciplinary research)

  6. Formation of magnetite nanoparticles at low temperature: from superparamagnetic to stable single domain particles.

    Directory of Open Access Journals (Sweden)

    Jens Baumgartner

    Full Text Available The room temperature co-precipitation of ferrous and ferric iron under alkaline conditions typically yields superparamagnetic magnetite nanoparticles below a size of 20 nm. We show that at pH  =  9 this method can be tuned to grow larger particles with single stable domain magnetic (> 20-30 nm or even multi-domain behavior (> 80 nm. The crystal growth kinetics resembles surprisingly observations of magnetite crystal formation in magnetotactic bacteria. The physicochemical parameters required for mineralization in these organisms are unknown, therefore this study provides insight into which conditions could possibly prevail in the biomineralizing vesicle compartments (magnetosomes of these bacteria.

  7. Low temperature synthesis, magnetic and electrical properties of iron-magnesium superparamagnetic nanoalloy

    Energy Technology Data Exchange (ETDEWEB)

    Nazir, Rabia [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Mazhar, Muhammad [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan)], E-mail: mazhar42pk@yahoo.com; Akhtar, Muhammad Javed; Nadeem, Muhammad; Siddique, Muhammad [Physics Division, Pinstech, P.O. Nilore, Islamabad (Pakistan); Shah, Raza [HEJ Research Institute of Chemistry, University of Karachi, Karachi 75270 (Pakistan); Hasanain, S. Khurshid [Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    2009-06-24

    A low temperature chemical approach which beats the miscibility barrier of Fe and Mg has been designed to synthesize Fe-Mg{sub 2} nanoalloy and tested to result nanoparticles of average 30 nm size. The nanoalloy is amorphous in nature and characterized by XPRD, AFM, magnetometery, Moessbauer and impedance spectroscopies. The result of magnetic measurement suggests the sample to be superparamagnetic as evidenced by the {sup 57}Fe Moessbauer spectroscopy. The two Mg atoms occupy different positions around iron resulting in two phase system as shown by Moessbauer and impedance spectroscopies.

  8. Low temperature synthesis, magnetic and electrical properties of iron-magnesium superparamagnetic nanoalloy

    International Nuclear Information System (INIS)

    Nazir, Rabia; Mazhar, Muhammad; Akhtar, Muhammad Javed; Nadeem, Muhammad; Siddique, Muhammad; Shah, Raza; Hasanain, S. Khurshid

    2009-01-01

    A low temperature chemical approach which beats the miscibility barrier of Fe and Mg has been designed to synthesize Fe-Mg 2 nanoalloy and tested to result nanoparticles of average 30 nm size. The nanoalloy is amorphous in nature and characterized by XPRD, AFM, magnetometery, Moessbauer and impedance spectroscopies. The result of magnetic measurement suggests the sample to be superparamagnetic as evidenced by the 57 Fe Moessbauer spectroscopy. The two Mg atoms occupy different positions around iron resulting in two phase system as shown by Moessbauer and impedance spectroscopies.

  9. Superparamagnetic nanoparticles for biomedical applications: Possibilities and limitations of a new drug delivery system

    Energy Technology Data Exchange (ETDEWEB)

    Neuberger, Tobias [Musculoskeletal Research Unit, Equine Hospital, Vetsuisse Faculty Zurich, University of Zurich, Winterthurerstr. 260, 8057 Zurich (Switzerland); Schoepf, Bernhard [Musculoskeletal Research Unit, Equine Hospital, Vetsuisse Faculty Zurich, University of Zurich, Winterthurerstr. 260, 8057 Zurich (Switzerland); Hofmann, Heinrich [Laboratory of Powder Technology, Institute of Materials, Swiss Federal Institute of Technology, EPFL, 1015 Lausanne (Switzerland); Hofmann, Margarete [MatSearch Pully, Chemin Jean Pavillard, 14, CH-1009 Pully (Switzerland); Rechenberg, Brigitte von [Musculoskeletal Research Unit, Equine Hospital, Vetsuisse Faculty Zurich, University of Zurich, Winterthurerstr. 260, 8057 Zurich (Switzerland)]. E-mail: bvonrechenberg@vetclinics.unizh.ch

    2005-05-15

    Nanoparticles can be used in biomedical applications, where they facilitate laboratory diagnostics, or in medical drug targeting. They are used for in vivo applications such as contrast agent for magnetic resonance imaging (MRI), for tumor therapy or cardiovascular disease. Very promising nanoparticles for these applications are superparamagnetic nanoparticles based on a core consisting of iron oxides (SPION) that can be targeted through external magnets. SPION are coated with biocompatible materials and can be functionalized with drugs, proteins or plasmids. In this review, the characteristics and applications of SPION in the biomedical sector are introduced and discussed.

  10. Superparamagnetic nanoparticles for biomedical applications: Possibilities and limitations of a new drug delivery system

    International Nuclear Information System (INIS)

    Neuberger, Tobias; Schoepf, Bernhard; Hofmann, Heinrich; Hofmann, Margarete; Rechenberg, Brigitte von

    2005-01-01

    Nanoparticles can be used in biomedical applications, where they facilitate laboratory diagnostics, or in medical drug targeting. They are used for in vivo applications such as contrast agent for magnetic resonance imaging (MRI), for tumor therapy or cardiovascular disease. Very promising nanoparticles for these applications are superparamagnetic nanoparticles based on a core consisting of iron oxides (SPION) that can be targeted through external magnets. SPION are coated with biocompatible materials and can be functionalized with drugs, proteins or plasmids. In this review, the characteristics and applications of SPION in the biomedical sector are introduced and discussed

  11. Incorporation and release of drug into/from superparamagnetic iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Maver, Uros; Bele, Marjan [National Institute of Chemistry Slovenia, Hajdrihova 19, 1000 Ljubljana (Slovenia); Makovec, Darko; Campelj, Stanislav [Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Jamnik, Janko [National Institute of Chemistry Slovenia, Hajdrihova 19, 1000 Ljubljana (Slovenia); Gaberscek, Miran [National Institute of Chemistry Slovenia, Hajdrihova 19, 1000 Ljubljana (Slovenia)], E-mail: miran.gaberscek@ki.si

    2009-10-15

    The aim of this study was to attach a model drug (naproxen) onto superparamagnetic iron oxide nanoparticles (SPION). First, SPION were coated with thin layer of silica that contained micropores. We demonstrated that such surface functionalization could be optimized by the use of citric acid which prevented SPION agglomeration during the procedure. HRTEM investigation showed a uniform 1-2-nm-thick silica coating around SPION. This coating did not affect significantly the magnetic properties of the SPION. Into the coated SPION we successfully incorporated about 30 wt% of naproxen. The latter was readily released after immersion into a testing solution. The composites could be interesting for potential use in diagnostics.

  12. Incorporation and release of drug into/from superparamagnetic iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Maver, Uros; Bele, Marjan; Makovec, Darko; Campelj, Stanislav; Jamnik, Janko; Gaberscek, Miran

    2009-01-01

    The aim of this study was to attach a model drug (naproxen) onto superparamagnetic iron oxide nanoparticles (SPION). First, SPION were coated with thin layer of silica that contained micropores. We demonstrated that such surface functionalization could be optimized by the use of citric acid which prevented SPION agglomeration during the procedure. HRTEM investigation showed a uniform 1-2-nm-thick silica coating around SPION. This coating did not affect significantly the magnetic properties of the SPION. Into the coated SPION we successfully incorporated about 30 wt% of naproxen. The latter was readily released after immersion into a testing solution. The composites could be interesting for potential use in diagnostics.

  13. Strategies for enumeration of circulating microvesicles on a conventional flow cytometer: Counting beads and scatter parameters.

    Science.gov (United States)

    Alkhatatbeh, Mohammad J; Enjeti, Anoop K; Baqar, Sara; Ekinci, Elif I; Liu, Dorothy; Thorne, Rick F; Lincz, Lisa F

    2018-01-01

    Enumeration of circulating microvesicles (MVs) by conventional flow cytometry is accomplished by the addition of a known amount of counting beads and calculated from the formula: MV/μl = (MV count/bead count) × final bead concentration. We sought to optimize each variable in the equation by determining the best parameters for detecting 'MV count' and examining the effects of different bead preparations and concentrations on the final calculation. Three commercially available bead preparations (TruCount, Flow-Count and CountBright) were tested, and MV detection on a BD FACSCanto was optimized for gating by either forward scatter (FSC) or side scatter (SSC); the results were compared by calculating different subsets of MV on a series of 74 typical patient plasma samples. The relationship between the number of beads added to each test and the number of beads counted by flow cytometry remained linear over a wide range of bead concentrations ( R 2 ≥ 0.997). However, TruCount beads produced the most consistent (concentration variation = 3.8%) calculated numbers of plasma CD41 + /Annexin V + MV, which were significantly higher from that calculated using either Flow-Count or CountBright ( p beads by FSC and 0.16 μm beads by SSC, but there were significantly more background events using SSC compared with FSC (3113 vs. 470; p = 0.008). In general, sample analysis by SSC resulted in significantly higher numbers of MV ( p beads provided linear results at concentrations ranging from 6 beads/μl to 100 beads/μl, but TruCount was the most consistent. Using SSC to gate MV events produced high background which negatively affected counting bead enumeration and overall MV calculations. Strategies to reduce SSC background should be employed in order to reliably use this technique.

  14. Induced movement of the magnetic beads and DNA-based dumbbell in a micro fluidic channel

    Science.gov (United States)

    Babić, B.; Ghai, R.; Dimitrov, K.

    2007-12-01

    We have explored controlled movement of magnetic beads and a dumbbell structure composed of DNA, a magnetic and a non-magnetic bead in a micro fluidic channel. Movement of the beads and dumbbells is simulated assuming that a net force is described as a superposition between the magnetic and hydrodynamic drag forces. Trajectories of beads and dumbbells are observed with optical light microscopy. The experimentally measured data show a good agreement with the simulations. This dynamical approach offers the prospect to stretch the DNA within the dumbbell and investigate its conformational changes. Further on, we demonstrate that short sonication can reduce multiple attachments of DNA to the beads.

  15. Stability of alginate-titanium dioxide based photocatalyst beads for water treatment application under UV irradiation

    OpenAIRE

    WENG HOONG LAM

    2017-01-01

    Immobilizing TiO2 photocatalyst in alginate beads has been considered to be a green approach for the separation and recycling of the photocatalyst in UV water treatment. However, the feasibility of using alginate beads in industry is largely dependent on their photo-stability during operation. This study aimed to provide a better understanding on the degradation of alginate/TiO2 beads under UV irradiation and to improve beads stability. The beads stability can be improved by increasing the al...

  16. Compositional characterization of sintered (U,Th)O2 pellets by EDXRF using fused bead specimens

    International Nuclear Information System (INIS)

    Sanjay Kumar, S.; Dhara, Sangita; Misra, N.L.; Aggarwal, S.K.

    2015-01-01

    Fused bead specimens were used for analyzing sintered (U,Th)O 2 pellets by Energy Dispersive X-Ray Fluorescence (EDXRF) spectrometry. The bead specimens of calibration mixtures U 3 O 8 and ThO 2 were made by fusing them in Lithium Tetraborate/Metaborate fusion mixtures using a fusion bead machine. The EDXRF spectra of these beads were used for making calibration plot for U% determination in (U+Th) amounts. Using these calibration plots and EDXRF spectra of bead of sintered (U,Th)O 2 pellets, U% in these pellets was successfully determined. (author)

  17. A sonochemical approach to the direct surface functionalization of superparamagnetic iron oxide nanoparticles with (3-aminopropyl)triethoxysilane.

    Science.gov (United States)

    Sodipo, Bashiru Kayode; Aziz, Azlan Abdul

    2014-01-01

    We report a sonochemical method of functionalizing superparamagnetic iron oxide nanoparticles (SPION) with (3-aminopropyl)triethoxysilane (APTES). Mechanical stirring, localized hot spots and other unique conditions generated by an acoustic cavitation (sonochemical) process were found to induce a rapid silanization reaction between SPION and APTES. FTIR, XPS and XRD measurements were used to demonstrate the grafting of APTES on SPION. Compared to what was reported in literature, the results showed that the silanization reaction time was greatly minimized. More importantly, the product displayed superparamagnetic behaviour at room temperature with a more than 20% higher saturation magnetization.

  18. Smooth and rapid microwave synthesis of MIL-53(Fe) including superparamagnetic γ-Fe2O3 nanoparticles

    Science.gov (United States)

    Wengert, Simon; Albrecht, Joachim; Ruoss, Stephen; Stahl, Claudia; Schütz, Gisela; Schäfer, Ronald

    2017-12-01

    MIL-53(Fe) linked to superparamagnetic γ-Fe2O3 nanoparticles was created using time-efficient microwave synthesis. Intermediates as well as the final product have been characterized by Dynamic Light Scattering (DLS), Infrared Spectroscopy (FTIR) and Thermal Gravimetric Analysis (TGA). It is found that this route allows the production of Fe nanoparticles with typical sizes of about 80 nm that are embedded inside the metal-organic structures. Detailed magnetization measurements using SQUID magnetometry revealed a nearly reversible magnetization loop indicating essentially superparamagnetic behavior.

  19. A planar conducting microstructure to guide and confine magnetic beads to a sensing zone

    KAUST Repository

    Gooneratne, Chinthaka Pasan

    2011-08-01

    A novel planar conducting microstructure is proposed to transport and confine magnetic micro/nano beads to a sensing zone. Manipulation and concentration of magnetic beads are achieved by employing square-shaped conducting micro-loops, with a few hundred nano-meters in thickness, arranged in a unique fashion. These microstructures are designed to produce high magnetic field gradients which are directly proportional to the force applied to manipulate the magnetic beads. Furthermore, the size of the microstructures allows greater maneuverability and control of magnetic beads than what could be achieved by permanent magnets. The aim of the microstructures is to guide magnetic beads from a large area and confine them to a smaller area where for example quantification would take place. Experiments were performed with different concentrations of 2 μm diameter magnetic beads. Experimental results showed that magnetic beads could be successfully guided and confined to the sensing zone. © 2011 Elsevier B.V. All rights reserved.

  20. Improvement of removal characteristics for uranium by immobilization of diphosil powder into alginate bead

    International Nuclear Information System (INIS)

    Kim, K. J.; Kang, I. S.; Lee, Y. H.; Son, J. S.; Hong, K. P.

    2003-01-01

    Chemical wastes containing small amounts of uranium can not be disposed of them as industrial wastes. Especially for the removal of uranium, In this study, the method of immobilizing Diphosil powder within alginate beads is adopted to make a bead from powdered resin. Sodium alginate bead itself showed a capability to uptake uranium to above 60%, but the value was decreased to below 30% after equilibrium. The rate of uranium adsorption increased with increasing content of Diphosil in sodium alginate bead. Diphosil resin itself showed very fast uptake of uranium from early stages, and then the rates were leveled off. Diphosil bead showed a improved capability to uptake uranium considering Diphosil content in the bead, and a considerable potential for further applications of a continuous process by using a bead form of Diphosil

  1. Separation of yttrium using carbon nanotube doped polymeric beads impregnated with D2EHPA

    International Nuclear Information System (INIS)

    Dasgupta, Kinshuk; Yadav, Kartikey K.; Singh, D.K.; Anitha, M.; Singh, H.

    2013-01-01

    Di-2-ethylhexyl phosphoric acid impregnated polyethersulfone based composite beads in combination with additives such as polyvinyl alcohol (PVA) and multiwalled carbon nanotube (MWCNT) has been prepared by non-solvent phase inversion method. The synthesized beads were characterized by scanning electron microscopy, thermogravimetry and infra-red spectroscopy. Effect of additives on bead morphology, solvent impregnation capacity, extractability and stability has been examined to compare their suitability for yttrium recovery from acidic medium. Microstructural investigation as well as experimental findings confirmed the role of additives in modifying the pore structures in beads, responsible for varied degree of yttrium extraction. Further the role of metal ion concentration in aqueous phase on its recovery by polymeric beads was also evaluated. Among the tested beads PES/D2EHPA/MWCNT/PVA beads were found to be superior for Y(Ill) extraction. (author)

  2. Bead Capture and Release on a Magnetic Sensor in a Microfluidic System

    DEFF Research Database (Denmark)

    Dalslet, Bjarke Thomas; Damsgaard, Christian Danvad; Freitas, S.C.

    Planar Hall effect magnetic sensors for detection of biological agents using surface treated magnetic beads are integrated with a fluid injection system. The response of the sensors is used to evaluate bead capture rates for different bead concentrations c and fluid flow rates Q, and to monitor...... subsequent removal of the beads. It is found that the capture rate scales directly with c and that it depends linearly on Q. At low Q the capture rate is only partially due to gravitational sedimentation of beads. At higher Q an additional term proportional to Q becomes important, which is attributed...... to capture of beads by the magnetic fields near the sensor. It is shown that beads can be washed off the sensor surface....

  3. On the occurrence of ‘bead lightning’ phenomena in long laboratory sparks

    Energy Technology Data Exchange (ETDEWEB)

    Vayanganie, S.P.A., E-mail: amilavayanganie@gmail.com [Atmospheric Physics and Lightning Research Group, University of Colombo, Colombo 03 (Sri Lanka); Cooray, V.; Rahman, Mahbubur; Hettiarachchi, Pasan; Diaz, Oscar [Lightning Research Group, The Ångström Laboratory Division of Electricity, Department of Engineering Sciences, Uppsala University, Box 534, SE-751 21 Uppsala (Sweden); Fernando, M. [Atmospheric Physics and Lightning Research Group, University of Colombo, Colombo 03 (Sri Lanka)

    2016-02-22

    The formation of bead lightning, where the lightning channel appears to break up into luminous fragments, is still an object of speculation. Here we report similar observations in laboratory discharges. Analysis of time resolved photographs shows that the discharge channel exhibits a ‘bead pattern’ in the decaying stage of the discharge and the occurrence of loops in the channel sections where the bead pattern is observed. This result presents the first evidence that the rapid cooling of non-uniform channel sections could lead to the formation of beads. It is suggested that periodically occurring non-uniform channel sections could explain the bead pattern of lightning discharges. - Highlights: • For the first time, the occurrence of bead patterns in the channel of laboratory sparks was reported. • Depending on the geometry some regions of the channel decays faster than the other sections. • A possible mechanism for the occurrence of beads in decaying states of lightning flashes is proposed.

  4. On the chemical variability of Middelburg glass beads and rods

    International Nuclear Information System (INIS)

    Karklins, K.; Kottman, J.; Hancock, R.G.V.; Sempowski, M.L.; Nohe, A.W.; Moreau, J.-F.; Aufreiter, S.; Kenyon, I.

    2001-01-01

    Forty-three glass samples from a late 16th-early 17th century, glass beadmaking house in Middelburg, the Netherlands, were selected for maximum colouring variability, including plain and multi-coloured varieties. The glass chemistries were quite diverse, within each colour grouping. For each single colour of glass, anticipated colouring elements (copper for turquoise blue, cobalt for dark blue, manganese for rose, and tin for white) were used, with the exception of two beads that were opacified wih antimony rather than with tin. Multi-coloured glass glasses (chevron beads) produced chemistries that match the mixing of the different coloured glasses. In some cases, low relative amounts of some inter-mixed glasses were not detectable against the composition of the major glass component. (author). 16 refs., 3 tabs

  5. Frictionless Demonstration Using Fine Plastic Beads For Teaching Mechanics

    International Nuclear Information System (INIS)

    Ishii, K.; Kagawa, K.; Khumaeni, A.; Kurniawan, K. H.

    2010-01-01

    New equipment for demonstrating laws of mechanics have successfully been constructed utilizing fine sphere plastic beads (0.3 mm in diameter). Fine plastic beads function as ball bearings to reduce the friction between the object and the plate surface. By this method, a quantitative measurement of energy conservation law has successfully been carried out with a small error of less 3%. The strong advantage of this frictionless method is that we can always use the same objects like Petri dishes for demonstrating many kinds of mechanics laws, such as the first, second, and the third laws of motion, momentum conservation law, and energy conservation law. This demonstration method surely has a beneficial effect for students, who can then understand mechanics laws systematically with a unified concept and no confusion.

  6. Methodological Study of Cell Separation with Domestic Immunomagnetic Beads

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    To establish the method of cell separation with domestic immuomagnetic beads, three methods were investigated. Direct method, SPA method and Biotin-Avidin method were applied to separate cell strain Hut-78 and CD4 positive cells. Separation rate of strain Hut-78 was more than 90 % in direct method. Detachment rate with papain was over 95 %. Cell activity was well retained. SPA method and Biotin-Avidin methods were also effective, but the direct method was superior to the other two techniques. Before separated by the direct method, CD4 positive cells constituted 46.4 %±6.4 % of mononuclear cells (MNC), but in eliminated suspension there was only 6.2 %±2.3 % CD4 positive cells left. In the separated part, 80.6 %±7.2 % of the cells combined with the beads. It is concluded that the direct method in separating cells had high sensitivity and specificity.

  7. Bead perturbation measurement for the KEK linac cavity

    International Nuclear Information System (INIS)

    Okumura, Shoji; Swenson, D.A.

    1975-03-01

    The axial electric field in the KEK linac cavity is measured by a bead perturbation method. The beat signal of around 1 kHz is generated with the rf signals from the cavity in self-excitation and from a signal generator whose output frequency is fixed. The period of the beat signal is measured by a counter in order to detect the small change in the resonant frequency of the cavity due to a bead perturbation. The counting data are transferred to a mini-computer after each period of the beat signal. The average fields of each gap are calculated in the computer and they are displayed on a storage oscilloscope. It takes about 50 seconds to complete the whole process of the measurement. The measuring system and the results obtained are described in this paper. (auth.)

  8. Plasticity of an Amorphous Assembly of Elastic Gel Beads

    Science.gov (United States)

    Grosshans, D.; Knaebel, A.; Lequeux, F.

    1995-01-01

    We have studied the rheological properties of an assembly of swollen gel beads in a lack of solvent. The system is an amorphous assembly of packed soft spheres in a given volume. We have studied the plastic behavior of the system, and interpreted it in terms of bead rearrangements within the assembly. Nous avons étudié les propriétés rhéologiques d'un assemblage de billes de gel gonflées en défaut de solvant. Le système est donc une assemblée amorphe de sphères molles écrasées à volume total constant. Nous avons étudié divers aspects du comportement plastique et nous l'avons interprété en termes de réorganisations de billes dans l'assemblage.

  9. Water dispersible superparamagnetic Cobalt iron oxide nanoparticles for magnetic fluid hyperthermia

    Energy Technology Data Exchange (ETDEWEB)

    Salunkhe, Ashwini B. [Centre for advanced materials research, Department of Physics, Savitribai Phule Pune University, Pune 411007 (India); Soft matter and molecular biophysics group, Department of Applied Physics, University of Santiago de Compostela, Santiago de Compostela (Spain); Khot, Vishwajeet M. [Department of Physics and Astronomy, University College London (United Kingdom); Ruso, Juan M. [Soft matter and molecular biophysics group, Department of Applied Physics, University of Santiago de Compostela, Santiago de Compostela (Spain); Patil, S.I., E-mail: patil@physics.unipune.ac.in [Centre for advanced materials research, Department of Physics, Savitribai Phule Pune University, Pune 411007 (India)

    2016-12-01

    Superparamagnetic nanoparticles of Cobalt iron oxide (CoFe{sub 2}O{sub 4}) are synthesized chemically, and dispersed in an aqueous suspension for hyperthermia therapy application. Different parameters such as magnetic field intensity, particle concentration which regulates the competence of CoFe{sub 2}O{sub 4} nanoparticle as a heating agents in hyperthermia are investigated. Specific absorption rate (SAR) decreases with increase in the particle concentration and increases with increase in applied magnetic field intensity. Highest value of SAR is found to be 91.84 W g{sup −1} for 5 mg. mL{sup −1} concentration. Oleic acid conjugated polyethylene glycol (OA-PEG) coated CoFe{sub 2}O{sub 4} nanoparticles have shown superior cyto-compatibility over uncoated nanoparticles to L929 mice fibroblast cell lines for concentrations below 2 mg. mL{sup −1}. Present work provides the underpinning for the use of CoFe{sub 2}O{sub 4} nanoparticles as a potential heating mediator for magnetic fluid hyperthermia. - Highlights: • Superparamagnetic, water dispersible CoFe{sub 2}O{sub 4} NPs were synthesized by simple and cost effective Co precipitation route. • Effect of coating on various physical and chemical properties of CoFe{sub 2}O{sub 4} NPs were studied. • The effect of coating on induction heating as well as biocompatibility of NPs were studied.

  10. Green synthesis of soya bean sprouts-mediated superparamagnetic Fe3O4 nanoparticles

    International Nuclear Information System (INIS)

    Cai Yan; Shen Yuhua; Xie Anjian; Li Shikuo; Wang Xiufang

    2010-01-01

    Superparamagnetic Fe 3 O 4 nanoparticles were first synthesized via soya bean sprouts (SBS) templates under ambient temperature and normal atmosphere. The reaction process was simple, eco-friendly, and convenient to handle. The morphology and crystalline phase of the nanoparticles were determined from scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and X-ray diffraction (XRD) spectra. The effect of SBS template on the formation of Fe 3 O 4 nanoparticles was investigated using X-ray photoemission spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR). The results indicate that spherical Fe 3 O 4 nanoparticles with an average diameter of 8 nm simultaneously formed on the epidermal surface and the interior stem wall of SBS. The SBS are responsible for size and morphology control during the whole formation of Fe 3 O 4 nanoparticles. In addition, the superconducting quantum interference device (SQUID) results indicate the products are superparamagnetic at room temperature, with blocking temperature (T B ) of 150 K and saturation magnetization of 37.1 emu/g.

  11. Green synthesis of soya bean sprouts-mediated superparamagnetic Fe 3O 4 nanoparticles

    Science.gov (United States)

    Cai, Yan; Shen, Yuhua; Xie, Anjian; Li, Shikuo; Wang, Xiufang

    2010-10-01

    Superparamagnetic Fe 3O 4 nanoparticles were first synthesized via soya bean sprouts (SBS) templates under ambient temperature and normal atmosphere. The reaction process was simple, eco-friendly, and convenient to handle. The morphology and crystalline phase of the nanoparticles were determined from scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and X-ray diffraction (XRD) spectra. The effect of SBS template on the formation of Fe 3O 4 nanoparticles was investigated using X-ray photoemission spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR). The results indicate that spherical Fe 3O 4 nanoparticles with an average diameter of 8 nm simultaneously formed on the epidermal surface and the interior stem wall of SBS. The SBS are responsible for size and morphology control during the whole formation of Fe 3O 4 nanoparticles. In addition, the superconducting quantum interference device (SQUID) results indicate the products are superparamagnetic at room temperature, with blocking temperature ( TB) of 150 K and saturation magnetization of 37.1 emu/g.

  12. Novel environmentally friendly synthesis of superparamagnetic magnetite nanoparticles using mechanochemical effect

    International Nuclear Information System (INIS)

    Iwasaki, Tomohiro; Kosaka, Kazunori; Watano, Satoru; Yanagida, Takeshi; Kawai, Tomoji

    2010-01-01

    A novel method for synthesizing superparamagnetic magnetite nanoparticles in water system via coprecipitation under an environmentally friendly condition has been developed. In this method, an almost neutral suspension containing ferrous hydroxide and goethite is used as the starting suspension and subjected to a ball-milling treatment. The product was characterized by transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, dynamic light scattering, superconducting quantum interference device magnetometry, and Moessbauer spectroscopy. The mechanochemical effect generated by the ball-milling treatment promoted the reaction between ferrous hydroxide and goethite even at room temperature, resulting in the formation of homogeneous magnetite nanoparticles. Simultaneously, it also contributed to crystallize the formed magnetite nanoparticles while inhibiting the particle growth. This resulted in the formation of ultrafine magnetite nanoparticles of about 10 nm having a single crystal structure. This method could provide ferromagnetic magnetite nanoparticles with superparamagnetism under the moderate condition without neither heating nor any additives such as surfactant and organic solvent.

  13. Dextran-coated superparamagnetic amorphous Fe–Co nanoalloy for magnetic resonance imaging applications

    International Nuclear Information System (INIS)

    An, Lu; Yu, Yanrong; Li, Xuejian; Liu, Wei; Yang, Hong; Wu, Dongmei; Yang, Shiping

    2014-01-01

    Graphical abstract: A dextran-coated Fe–Co nanoalloy was developed serving as a sensitive contrast agent for magnetic resonance imaging applications. - Highlights: • Amorphous Fe–Co nanoalloy was prepared via wet chemical reduction approach. • The Fe–Co nanoalloy is water-soluble, stable, and biocompatible. • The Fe–Co nanoalloy is superparamagnetic. • The Fe–Co nanoalloy exhibits T 2 -weighted MR enhancement both in vitro and in vivo. - Abstract: For magnetic resonance imaging applications, a facile approach for water-soluble dextran coated amorphous Fe–Co nanoalloy was developed. The as-synthesized nanoalloy had a diameter of 9 nm with a narrow size distribution and showed superparamagnetic property with a saturated magnetization (Ms) of 25 emu/g. In vitro cytotoxicity test revealed that it was biocompatible at a concentration below 120 μg/mL. It can be uptaken by HeLa cells effectively and resulted in the obvious T 2 effect after internalization. Biodistribution studies in conjunction with inductively coupled plasma-atomic emission spectroscopy (ICP-AES) confirmed that Fe–Co nanoalloy was preferentially accumulated in lung and spleen after intravenous injection for 4 h. In vivo MRI, dextran-coated Fe–Co nanoalloy can serve as a sensitive contrast agent for MR imaging, especially in the spleen, so we believe that it maybe hold great promise for diagnosis of splenic disease by appropriately functionalizing their surface

  14. Cotunneling enhancement of magnetoresistance in double magnetic tunnel junctions with embedded superparamagnetic NiFe nanoparticles

    International Nuclear Information System (INIS)

    Dempsey, K.J.; Arena, D.; Hindmarch, A.T.; Wei, H.X.; Qin, Q.H.; Wen, Z.C.; Wang, W.X.; Vallejo-Fernandez, G.; Han, X.F.; Marrows, C.H.

    2010-01-01

    Temperature and bias voltage-dependent transport characteristics are presented for double magnetic tunnel junctions (DMTJs) with self-assembled NiFe nanoparticles embedded between insulating alumina barriers. The junctions with embedded nanoparticles are compared to junctions with a single barrier of comparable size and growth conditions. The embedded particles are characterized using x-ray absorption spectroscopy, transmission electron microscopy, and magnetometry techniques, showing that they are unoxidized and remain superparamagnetic to liquid helium temperatures. The tunneling magnetoresistance (TMR) for the DMTJs is lower than the control samples, however, for the DMTJs an enhancement in TMR is seen in the Coulomb blockade region. Fitting the transport data in this region supports the theory that cotunneling is the dominant electron transport process within the Coulomb blockade region, sequential tunneling being suppressed. We therefore see an enhanced TMR attributed to the change in the tunneling process due to the interplay of the Coulomb blockade and spin-dependent tunneling through superparamagnetic nanoparticles, and develop a simple model to quantify the effect, based on the fact that our nanoparticles will appear blocked when measured on femtosecond tunneling time scales.

  15. Magnetic and relaxometric properties of polyethylenimine-coated superparamagnetic MRI contrast agents

    International Nuclear Information System (INIS)

    Corti, M.; Lascialfari, A.; Marinone, M.; Masotti, A.; Micotti, E.; Orsini, F.; Ortaggi, G.; Poletti, G.; Innocenti, C.; Sangregorio, C.

    2008-01-01

    Novel systems to be employed as superparamagnetic contrast agents (CA) for magnetic resonance imaging (MRI) have been synthesized. These compounds are composed of an iron oxide magnetic core coated by polyethylenimine (PEI) or carboxylated polyethylenimine (PEI-COOH). The aim of the present work was to prepare and study new nanostructured systems (with better or at least comparable relaxivities, R 1 and R 2 , with respect to the commercial ones) with controlled, almost monodisperse average dimensions and shape, as candidates for molecular targeting. By means of atomic force microscopy (AFM) measurements we determined the average diameter, of the order of 200 nm, and the shape of the particles. The superparamagnetic behavior was assessed by SQUID measurements. From X-ray data the estimated average diameters of the magnetic cores were found to be ∼5.8 nm for PEI-COOH60 and ∼20 nm for the compound named PEI25. By NMR-dispersion (NMRD), we found that PEI-COOH60 presents R 1 and R 2 relaxivities slightly lower than Endorem. The experimental results suggest that these novel compounds can be used as MRI CA

  16. Dextran-coated superparamagnetic amorphous Fe–Co nanoalloy for magnetic resonance imaging applications

    Energy Technology Data Exchange (ETDEWEB)

    An, Lu; Yu, Yanrong; Li, Xuejian; Liu, Wei [The Key Laboratory of Resource Chemistry of Ministry of Education and Shanghai Key Laboratory of Rare Earth Functional Materials, Department of Chemistry, Shanghai Normal University, Shanghai 200234 (China); Yang, Hong, E-mail: yanghong@shnu.edu.cn [The Key Laboratory of Resource Chemistry of Ministry of Education and Shanghai Key Laboratory of Rare Earth Functional Materials, Department of Chemistry, Shanghai Normal University, Shanghai 200234 (China); Wu, Dongmei [Shanghai Key Laboratory of Magnetic Resonance, Department of Physics, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062 (China); Yang, Shiping, E-mail: shipingy@shnu.edu.cn [The Key Laboratory of Resource Chemistry of Ministry of Education and Shanghai Key Laboratory of Rare Earth Functional Materials, Department of Chemistry, Shanghai Normal University, Shanghai 200234 (China)

    2014-01-01

    Graphical abstract: A dextran-coated Fe–Co nanoalloy was developed serving as a sensitive contrast agent for magnetic resonance imaging applications. - Highlights: • Amorphous Fe–Co nanoalloy was prepared via wet chemical reduction approach. • The Fe–Co nanoalloy is water-soluble, stable, and biocompatible. • The Fe–Co nanoalloy is superparamagnetic. • The Fe–Co nanoalloy exhibits T{sub 2}-weighted MR enhancement both in vitro and in vivo. - Abstract: For magnetic resonance imaging applications, a facile approach for water-soluble dextran coated amorphous Fe–Co nanoalloy was developed. The as-synthesized nanoalloy had a diameter of 9 nm with a narrow size distribution and showed superparamagnetic property with a saturated magnetization (Ms) of 25 emu/g. In vitro cytotoxicity test revealed that it was biocompatible at a concentration below 120 μg/mL. It can be uptaken by HeLa cells effectively and resulted in the obvious T{sub 2} effect after internalization. Biodistribution studies in conjunction with inductively coupled plasma-atomic emission spectroscopy (ICP-AES) confirmed that Fe–Co nanoalloy was preferentially accumulated in lung and spleen after intravenous injection for 4 h. In vivo MRI, dextran-coated Fe–Co nanoalloy can serve as a sensitive contrast agent for MR imaging, especially in the spleen, so we believe that it maybe hold great promise for diagnosis of splenic disease by appropriately functionalizing their surface.

  17. New magnetic nanobiocomposite based in galactomannan/glycerol and superparamagnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Souza, N.D.G.; Freire, R.M.; Cunha, A.P. [Grupo de Química de Materiais Avançados (GQMAT), Departamento de Química Analítica e Físico-Química, Universidade Federal do Ceará – UFC, Campus do Pici, CP 12100, CEP 60451-970 Fortaleza, CE (Brazil); Silva, M.A.S. da [LOCEM – Laboratório de Telecomunicações e Ciência e Engenharia de Materiais, Departamento de Física, Universidade Federal do Ceará, Fortaleza, CE (Brazil); Mazzetto, S.E. [Grupo de Química de Materiais Avançados (GQMAT), Departamento de Química Analítica e Físico-Química, Universidade Federal do Ceará – UFC, Campus do Pici, CP 12100, CEP 60451-970 Fortaleza, CE (Brazil); Sombra, A.S.B. [LOCEM – Laboratório de Telecomunicações e Ciência e Engenharia de Materiais, Departamento de Física, Universidade Federal do Ceará, Fortaleza, CE (Brazil); Denardin, J.C. [Departamento de Física, Universidad de Santiago de Chile, USACH, Av. Ecuador 3493, Santiago (Chile); and others

    2015-04-15

    In this study, magnetic nanobiocomposites were prepared in different proportions and produced with galactomannan (GM), magnetic nanoparticles of NiZn and glycerol (GL). The microstructure and morphology of the samples were characterized by Scanning Electron Microscopy (SEM), X-ray powder diffraction, Fourier transform infrared (FTIR) spectroscopy, Thermal analysis (TG) and Differential scanning calorimetry (DSC). The magnetic and dielectric behavior of the films was studied by Vibrating sample magnetometer (VSM) and Impedance spectroscopy. The results showed efficient incorporation of NiZn in the polymer matrix. The degradation profiles presented thermal events that were confirmed by endothermic and exothermic processes from DSC measurements. Films presented saturation magnetization (M{sub s}) range from 6 to 17 emu/g and superparamagnetic behavior. It was observed that the values of dielectric constant increased as a function of the nanoparticles concentration in the bionacomposite. Thus, this kind of biocomposite could be used as a versatile magnetic-dielectric in microwave devices. - Highlights: • Incorporation of inorganic nanoparticles in the galactomannan/glycerol polymer matrix. • All nanobiocomposites presented superparamagnetic behavior. • It can be employed as a versatile material, due to their flexible and dielectric-magnetic features.

  18. Chondroitin sulfate-capped super-paramagnetic iron oxide nanoparticles as potential carriers of doxorubicin hydrochloride.

    Science.gov (United States)

    Mallick, Neha; Anwar, Mohammed; Asfer, Mohammed; Mehdi, Syed Hassan; Rizvi, Mohammed Moshahid Alam; Panda, Amulya Kumar; Talegaonkar, Sushama; Ahmad, Farhan Jalees

    2016-10-20

    Chondroitin-4-sulfate (CS), a glycosaminoglycan, was used to prepare CS-capped super-paramagnetic iron oxide nanoparticles, which were further employed for loading a water-soluble chemotherapeutic agent (doxorubicin hydrochloride, DOX). CS-capped SPIONs have potential biomedical application in cancer targeting. The optimized formulation had a hydrodynamic size of 91.2±0.8nm (PDI; 0.228±0.004) and zeta potential of -49.1±1.66mV. DOX was loaded onto the formulation up to 2% (w/w) by physical interaction with CS. TEM showed nano-sized particles having a core-shell structure. XRD confirmed crystal phase of iron oxide. FT-IR conceived the interaction of iron oxide with CS as bidentate chelation and also confirmed DOX loading. Vibration sample magnetometry confirmed super-paramagnetic nature of nanoparticles, with saturation magnetization of 0.238emug(-1). In vitro release profile at pH 7.4 showed that 96.67% of DOX was released within 24h (first order kinetics). MTT assay in MCF7 cells showed significantly higher (p<0.0001) cytotoxicity for DOX in SPIONs than DOX solution (IC50 values 6.294±0.4169 and 11.316±0.1102μgmL(-1), respectively). Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mandel, K., E-mail: karl-sebastian.mandel@isc.fraunhofer.de [Fraunhofer Institute for Silicate Research, ISC, Neunerplatz 2, 97082 Würzburg (Germany); University Würzburg, Chair of Chemical Technology of Materials Synthesis, Röntgenring 11, 97070 Würzburg (Germany); Hutter, F., E-mail: frank.hutter@isc.fraunhofer.de [Fraunhofer Institute for Silicate Research, ISC, Neunerplatz 2, 97082 Würzburg (Germany); Gellermann, C., E-mail: carsten.gellermann@isc.fraunhofer.de [Fraunhofer Institute for Silicate Research, ISC, Neunerplatz 2, 97082 Würzburg (Germany); Sextl, G., E-mail: gerhard.sextl@isc.fraunhofer.de [Fraunhofer Institute for Silicate Research, ISC, Neunerplatz 2, 97082 Würzburg (Germany); University Würzburg, Chair of Chemical Technology of Materials Synthesis, Röntgenring 11, 97070 Würzburg (Germany)

    2013-04-15

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

  20. Molecularly Imprinted Polymer Beads-Synthesis, Evaluation and Applications

    OpenAIRE

    Zhou, Tongchang

    2016-01-01

    Molecularly imprinted polymers (MIPs) are artificial receptors designed for the selective recognition of template molecules. These polymers have been applied in analytical separations, as chemical sensors and in drug delivery system due to their low cost and high stability. In recent years MIP beads, especially those with good selectivity in aqueous solution, have become attractive as they can be potentially used as selective adsorbents for the solid phase extraction (SPE) and chromatographic...

  1. Hot wire TIG temper bead welding for nuclear repairs

    International Nuclear Information System (INIS)

    Lambert, J.A.; Gilston, P.F.

    1989-08-01

    A preliminary assessment has been carried out to determine the suitability of the hot wire tungsten inert gas (TIG) welding process for the repair of thick section, ferritic steel nuclear pressure vessels. The objective has been to identify a hot wire TIG temper bead procedure, suitable for repairs without post weld heat treatment. This procedure involves depositing two weld layers with carefully selected welding parameters such that overlapping thermal cycles produce a refined and tempered heat affected zone, HAZ, microstructure. (author)

  2. HOM identification by bead pulling in the Brookhaven ERL cavity

    CERN Document Server

    Hahn, H; Jain, Puneet; Johnson, Elliott C; Xu, Wencan

    2014-01-01

    Exploratory measurements of the Brookhaven Energy Recovery Linac (ERL) cavity at superconducting temperature produced a long list of high order modes (HOMs). The niobium 5-cell cavity is terminated at each end with HOM ferrite dampers that successfully reduce the Q-factors to levels required to avoid beam break up (BBU) instabilities. However, a number of un-damped resonances with Q≥106 were found at 4 K and their mode identification forms the focus of this paper. The approach taken here consists of bead pulling on a copper (Cu) replica of the ERL cavity with dampers involving various network analyzer measurements. Several different S21 transmission measurements are used, including those taken from the fundamental input coupler to the pick-up probe across the cavity, others between beam-position monitor probes in the beam tubes, and also between probes placed into the cells. The bead pull technique suitable for HOM identification with a metallic needle or dielectric bead is detailed. This paper presents the...

  3. Chitosan and chemically modified chitosan beads for acid dyes sorption

    Institute of Scientific and Technical Information of China (English)

    AZLAN Kamari; WAN SAIME Wan Ngah; LAI KEN Liew

    2009-01-01

    The capabilities of chitosan and chitosan-EGDE (ethylene glycol diglycidyl ether) beads for removing Acid Red 37 (AR 37) and Acid Blue 25 (AB 25) from aqueous solution were examined. Chitosan beads were cross-linked with EGDE to enhance its chemical resistance and mechanical strength. Experiments were performed as a function of pH, agitation period and concentration of AR 37 and AB 25. It was shown that the adsorption capacities of chitosan were comparatively higher than chitosan-EGDE for both acid dyes. This is mainly because cross-linking using EGDE reduces the major adsorption sites -NH3+ on chitosan. Langmuir isotherm model showed best conformity compared to Freundlich and BET. The kinetic experimental data agreed very well to the pseudo second-order kinetic model. The desorption study revealed that after three cycles of adsorption and desorption by NaOH and HCl, both adsorbents retained their promising adsorption abilities. FT-IR analysis proved that the adsorption of acid dyes onto chitosan-based adsorbents was a physical adsorption. Results also showed that chitosan and chitosan-EGDE beads were favourable adsorbers and could be employed as low-cost alternatives for the removal of acid dyes in wastewater treatment.

  4. Universal approach for selective trace metal determinations via sequential injection-bead injection-lab-on-valve using renewable hydrophobic bead surfaces as reagent carriers

    DEFF Research Database (Denmark)

    Long, Xiangbao; Miró, Manuel; Hansen, Elo Harald

    2005-01-01

    involves the use of poly(styrene-divinylbenzene) beads containing pendant octadecyl moieties (C18-PS/DVB), which are preimpregnated with a selective organic metal chelating agent prior to the automatic manipulation of the beads in the microbore conduits of the LOV unit. By adapting this approach...

  5. Preparation of Glutaraldehyde Cross-Linked Chitosan Beads Under Microwave Irradiation and Properties of Urease Immobilized onto the Beads

    Institute of Scientific and Technical Information of China (English)

    LIANG Zupei; FENG Yaqing; MENG Shuxian; ZHANG Weihong

    2005-01-01

    The glutaraldehyde cross-linked chitosan beads were prepared under microwave irradiation and urease was immobilized onto the beads. The activity and the yield of enzyme activity of the immobilized urease were 10.83 U/g carrier and 47.7%, respectively. The optimum conditions of immobilization were 1% of glutaraldehyde volume fraction, 10 mg/g of urease/beads weight ratio, 24 h of the processing time and pH 6.5 of the reaction medium for immobilization. The properties of the immobilized urease were investigated and compared with those of the free enzyme. The optimum pH values were 6.5 and 7.0 for the immobilized and free urease, respectively. The optimum temperature was 60 ℃ for the free urease, while it shifted to 65 ℃ for the immobilized enzyme. The Michaelis constant K m was 9.1 mmol/L for the immobilized and 12.5 mmol/L for the free urease. The immobilized urease retained 40% of its initial enzyme activity even after 10 repeated uses. The immobilized urease stored at 4 ℃ retained 46% of its initial activity even after 35 d.

  6. Preparation and characterization of chitosan/cashew gum beads loaded with Lippia sidoides essential oil

    Energy Technology Data Exchange (ETDEWEB)

    Paula, Haroldo C.B., E-mail: hpaula@ufc.br [Department of Analytical and Physical Chemistry, Federal University of Ceara, UFC, Fortaleza-CE (Brazil); Sombra, Fernanda Matoso; Cavalcante, Rafaela de Freitas; Abreu, Flavia O.M.S. [Department of Analytical and Physical Chemistry, Federal University of Ceara, UFC, Fortaleza-CE (Brazil); Paula, Regina C.M. de [Department of Organic and Inorganic Chemistry, Federal University of Ceara, UFC, Fortaleza-CE (Brazil)

    2011-03-12

    Beads based on chitosan (CH) and cashew gum (CG), were prepared and loaded with an essential oil with larvicide activity (Lippia sidoides - Ls). CH and CH-CG beads were characterized by scanning electron microscopy (SEM), infrared and UV-VIS spectroscopy, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), as well as, regarding their larvicide loading, swelling, in vitro and in vivo release kinetics. The oil encapsulation was evidenced by FTIR analysis and LS loading ranges from 2.4% to 4.4%. CH beads duly showed swelling degree (Q) values from 4.0 to 6.7, reaching equilibrium after 30 min, whereas crosslinked CH-CG beads showed lower swelling values, from 0.4 to 3.8, exhibiting a longer equilibrium time. Liquid transport parameters have revealed diffusion coefficient for CH-CG beads, as low as 2 x 10{sup -15} m{sup 2}/s. TGA and DSC revealed that CH:CG crosslinked beads are more thermally stable than CH beads. In vitro release follows a non-Fickian diffusion profile for both bead types, however, and a prolonged release being achieved only after beads crosslinking. In vivo release showed that both CH and CH-CG presented a prolonged larvicide effect. These aforesaid results, indicate that CH-CG beads loaded with LS are efficient for A. aegypti larval control.

  7. Preparation and characterization of chitosan/cashew gum beads loaded with Lippia sidoides essential oil

    International Nuclear Information System (INIS)

    Paula, Haroldo C.B.; Sombra, Fernanda Matoso; Cavalcante, Rafaela de Freitas; Abreu, Flavia O.M.S.; Paula, Regina C.M. de

    2011-01-01

    Beads based on chitosan (CH) and cashew gum (CG), were prepared and loaded with an essential oil with larvicide activity (Lippia sidoides - Ls). CH and CH-CG beads were characterized by scanning electron microscopy (SEM), infrared and UV-VIS spectroscopy, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), as well as, regarding their larvicide loading, swelling, in vitro and in vivo release kinetics. The oil encapsulation was evidenced by FTIR analysis and LS loading ranges from 2.4% to 4.4%. CH beads duly showed swelling degree (Q) values from 4.0 to 6.7, reaching equilibrium after 30 min, whereas crosslinked CH-CG beads showed lower swelling values, from 0.4 to 3.8, exhibiting a longer equilibrium time. Liquid transport parameters have revealed diffusion coefficient for CH-CG beads, as low as 2 x 10 -15 m 2 /s. TGA and DSC revealed that CH:CG crosslinked beads are more thermally stable than CH beads. In vitro release follows a non-Fickian diffusion profile for both bead types, however, and a prolonged release being achieved only after beads crosslinking. In vivo release showed that both CH and CH-CG presented a prolonged larvicide effect. These aforesaid results, indicate that CH-CG beads loaded with LS are efficient for A. aegypti larval control.

  8. Elution of Clindamycin and Enrofloxacin From Calcium Sulfate Hemihydrate Beads In Vitro.

    Science.gov (United States)

    Phillips, Heidi; Boothe, Dawn M; Bennett, R Avery

    2015-11-01

    To compare the in vitro elution characteristics of clindamycin and enrofloxacin from calcium sulfate hemihydrate beads containing a single antibiotic, both antibiotics, and each antibiotic incubated in the same eluent well. Experimental in vitro study. Calcium sulfate hemihydrate beads were formed by mixing with clindamycin and/or enrofloxacin to create 4 study groups: (1) 160 mg clindamycin/10 beads; (2) 160 mg enrofloxacin/10 beads; (3) 160 mg clindamycin + 160 mg enrofloxacin/10 beads; and (4) 160 mg clindamycin/5 beads and 160 mg enrofloxacin/5 beads. Chains of beads were formed in triplicate and placed in 5 mL phosphate buffered saline (PBS; pH 7.4 and room temperature) with constant agitation. Antibiotic-conditioned PBS was sampled at 14 time points from 1 hour to 30 days. Clindamycin and enrofloxacin concentrations in PBS were determined using high-performance liquid chromatography. Eluent concentrations from clindamycin-impregnated beads failed to remain sufficiently above minimum inhibitory concentration (MIC) for common infecting bacteria over the study period. Enrofloxacin eluent concentrations remained sufficiently above MIC for common wound pathogens of dogs and cats and demonstrated an atypical biphasic release pattern. No significant differences in elution occurred as a result of copolymerization of the antibiotics into a single bead or from individual beads co-eluting in the same eluent well. Clindamycin-impregnated beads cannot be recommended for treatment of infection at the studied doses; however, use of enrofloxacin-impregnated beads may be justified when susceptible bacteria are cultured. © Copyright 2015 by The American College of Veterinary Surgeons.

  9. Comparison of four supports for adsorption of reactive dyes by immobilized Aspergillus fumigatus beads

    Institute of Scientific and Technical Information of China (English)

    WANG Bao-e; HU Yong-you

    2007-01-01

    Four materials, sodium carboxymethylcellulose (Na-CMC), sodium alginate (SA), polyvinyl alcohol (PVA), and chitosan (CTS), were prepared as supports for entrapping fungus Aspergillus fumigatus. The adsorption of synthetic dyes, reactive brilliant blue KN-R, and reactive brilliant red K-2BP, by these immobilized gel beads and plain gel beads was evaluated. The adsorption efficiencies of reactive brilliant red K-2BP and reactive brilliant blue KN-R by CTS immobilized beads were 89.1% and 93.5% in 12 h, respectively. The adsorption efficiency by Na-CMC immobilized beads was slightly lower than that of mycelial pellets. But the dye culture mediums were almost completely decolorized in 48 h using the above-mentioned two immobilized beads (exceeding 95%). The adsorption efficiency by SA immobilized beads exceeded 92% in 48 h. PVA-SA immobilized beads showed the lowest adsorption efficiency, which was 79.8% for reactive brilliant red K-2BP and 92.5% for reactive brilliant blue KN-R in 48 h. Comparing the adsorption efficiency by plain gel beads, Na-CMC plain gel beads ranked next to CTS ones. SA and PVA-SA plain gel beads hardly had the ability of adsorbing dyes. Subsequently, the growth of mycelia in Na-CMC and SA immobilized beads were evaluated. The biomass increased continuously in 72 h. The adsorption capacity of reactive brilliant red K-2BP and reactive brilliant blue KN-R by Na-CMC immobilized beads was 78.0 and 86.7 mg/g, respectively. The SEM micrographs show that the surface structure of Na-CMC immobilized bead is loose and finely porous, which facilitates diffusion of the dyes.

  10. Methodology description for detection of cellular uptake of PVA coated superparamagnetic iron oxide nanoparticles (SPION) in synovial cells of sheep

    International Nuclear Information System (INIS)

    Schoepf, Bernhard; Neuberger, Tobias; Schulze, Katja; Petri, Alke; Chastellain, Matthieu; Hofmann, Margarete; Hofmann, Heinrich; Rechenberg, Brigitte von

    2005-01-01

    The detection of superparamagnetic iron oxide nanoparticles (SPION) in synoviocytes is reported. Synoviocytes were incubated for 2, 12, 24 and 48 h with 1.5 mg/ml of PVA coated SPION under the influence of magnets (12 h). Particles were well tolerated by the synoviocytes, were easily detected using the Turnbulls and Prussian blue reactions between 12 and 24 h

  11. Methodology description for detection of cellular uptake of PVA coated superparamagnetic iron oxide nanoparticles (SPION) in synovial cells of sheep

    Energy Technology Data Exchange (ETDEWEB)

    Schoepf, Bernhard [Musculoskeletal Research Unit, Equine Hospital, Vetsuisse Faculty Zurich, University of Zurich, Winterthurerstr. 260, 8057 Zurich (Switzerland); Neuberger, Tobias [Musculoskeletal Research Unit, Equine Hospital, Vetsuisse Faculty Zurich, University of Zurich, Winterthurerstr. 260, 8057 Zurich (Switzerland); Schulze, Katja [Musculoskeletal Research Unit, Equine Hospital, Vetsuisse Faculty Zurich, University of Zurich, Winterthurerstr. 260, 8057 Zurich (Switzerland); Petri, Alke [Powder Technology Laboratory, Institute of Materials, Swiss Federal Institute of Technology Lausanne, EPFL, MX-D Ecublens, 1015 Lausanne (Switzerland); Chastellain, Matthieu [Powder Technology Laboratory, Institute of Materials, Swiss Federal Institute of Technology Lausanne, EPFL, MX-D Ecublens, 1015 Lausanne (Switzerland); Hofmann, Margarete [MatSearch, Ch. Jean Pavillard 14, 1009 Pully (Switzerland); Hofmann, Heinrich [Powder Technology Laboratory, Institute of Materials, Swiss Federal Institute of Technology Lausanne, EPFL, MX-D Ecublens, 1015 Lausanne (Switzerland); Rechenberg, Brigitte von [Musculoskeletal Research Unit, Equine Hospital, Vetsuisse Faculty Zurich, University of Zurich, Winterthurerstr. 260, 8057 Zurich (Switzerland)]. E-mail: bvonrechenberg@vetclinics.unizh.ch

    2005-05-15

    The detection of superparamagnetic iron oxide nanoparticles (SPION) in synoviocytes is reported. Synoviocytes were incubated for 2, 12, 24 and 48 h with 1.5 mg/ml of PVA coated SPION under the influence of magnets (12 h). Particles were well tolerated by the synoviocytes, were easily detected using the Turnbulls and Prussian blue reactions between 12 and 24 h.

  12. Safeguards Analytical Laboratory evaluation program. Part 1. Resin bead mass spectrometry. Part 2. Results of a resin bead field experiment-Tastex-J

    International Nuclear Information System (INIS)

    Walker, R.L.; Smith, D.H.; Carter, J.A.; Musick, W.R.; Donohue, D.L.; Deron, S.; Asakura, Y.; Kagami, K.; Irinouchi, S.; Masui, J.

    1981-01-01

    The first part of this report covers background of resin bead spectrometry and the new batch resin bead method. In the original technique, about ten anion resin beads in the nitrate form were exposed to the diluted sample solution. The solution was adjusted to be a 8 M HNO 3 and to have about 1 μg U per bead. Up to 48 hours of static contact between beads and solution was required for adsorption of 1 to 3 ng Pu and U per bead to be achieved. Under these conditions, contamination was a problem at reprocessing facilities. The new batch techniques reduces the risk of contamination by handling one hundred times more U in the final diluted sample which is exposed to a proportionately larger number of beads. Moreover, it only requires ten minutes adsorption time to provide about 1000 purified samples for mass spectrometry. The amounts of Pu and U adsorbed versus time were determined and results are tabulated. The second part of this report briefly summarizes results of resin bead field tests completed at the Power Reactor and Nuclear Fuel Development Corporation (PNC) reprocessing plant in Tokai-mura, Japan. Both methods, the original small-sample resin bead and the batch technique, were investigated on spent fuel solutions. Beads were prepared at PNC and distributed to IAEA and ORNL along with dried residues for conventional mass spectrometric analysis at IAEA. Parallel measurements were made at PNC using their normal measuring routines. The U and Pu measurements of all resin and those of PNC are in excellent agreement for the batch method. Discrepancies were noted in the U measurements by the original method

  13. Targeting experimental orthotopic glioblastoma with chitosan-based superparamagnetic iron oxide nanoparticles (CS-DX-SPIONs).

    Science.gov (United States)

    Shevtsov, Maxim; Nikolaev, Boris; Marchenko, Yaroslav; Yakovleva, Ludmila; Skvortsov, Nikita; Mazur, Anton; Tolstoy, Peter; Ryzhov, Vyacheslav; Multhoff, Gabriele

    2018-01-01

    Glioblastoma is the most devastating primary brain tumor of the central nervous system in adults. Magnetic nanocarriers may help not only for a targeted delivery of chemotherapeutic agents into the tumor site but also provide contrast enhancing properties for diagnostics using magnetic resonance imaging (MRI). Synthesized hybrid chitosan-dextran superparamagnetic nanoparticles (CS-DX-SPIONs) were characterized using transmission electron microscopy (TEM) and relaxometry studies. Nonlinear magnetic response measurements were employed for confirming the superparamagnetic state of particles. Following in vitro analysis of nanoparticles cellular uptake tumor targeting was assessed in the model of the orthotopic glioma in rodents. CS-DX-SPIONs nanoparticles showed a uniform diameter of 55 nm under TEM and superparamagentic characteristics as determined by T 1 (spin-lattice relaxation time) and T 2 (spin-spin relaxation time) proton relaxation times. Application of the chitosan increased the charge from +8.9 to +19.3 mV of the dextran-based SPIONs. The nonlinear magnetic response at second harmonic of CS-DX-SPIONs following the slow change of stationary magnetic fields with very low hysteresis evidenced superparamagnetic state of particles at ambient temperatures. Confocal microscopy and flow cytometry studies showed an enhanced internalization of the chitosan-based nanoparticles in U87, C6 glioma and HeLa cells as compared to dextran-coated particles. Cytotoxicity assay demonstrated acceptable toxicity profile of the synthesized nanoparticles up to a concentration of 10 μg/ml. Intravenously administered CS-DX-SPIONs in orthotopic C6 gliomas in rats accumulated in the tumor site as shown by high-resolution MRI (11.0 T). Retention of nanoparticles resulted in a significant contrast enhancement of the tumor image that was accompanied with a dramatic drop in T 2 values ( P chitosan-dextran magnetic particles demonstrated high MR contrast enhancing properties for the

  14. FUZZY REGRESSION MODEL TO PREDICT THE BEAD GEOMETRY IN THE ROBOTIC WELDING PROCESS

    Institute of Scientific and Technical Information of China (English)

    B.S. Sung; I.S. Kim; Y. Xue; H.H. Kim; Y.H. Cha

    2007-01-01

    Recently, there has been a rapid development in computer technology, which has in turn led todevelop the fully robotic welding system using artificial intelligence (AI) technology. However, therobotic welding system has not been achieved due to difficulties of the mathematical model andsensor technologies. The possibilities of the fuzzy regression method to predict the bead geometry,such as bead width, bead height, bead penetration and bead area in the robotic GMA (gas metalarc) welding process is presented. The approach, a well-known method to deal with the problemswith a high degree of fuzziness, is used to build the relationship between four process variablesand the four quality characteristics, respectively. Using these models, the proper prediction of theprocess variables for obtaining the optimal bead geometry can be determined.

  15. Polymerase chain reaction system using magnetic beads for analyzing a sample that includes nucleic acid

    Science.gov (United States)

    Nasarabadi, Shanavaz [Livermore, CA

    2011-01-11

    A polymerase chain reaction system for analyzing a sample containing nucleic acid includes providing magnetic beads; providing a flow channel having a polymerase chain reaction chamber, a pre polymerase chain reaction magnet position adjacent the polymerase chain reaction chamber, and a post pre polymerase magnet position adjacent the polymerase chain reaction chamber. The nucleic acid is bound to the magnetic beads. The magnetic beads with the nucleic acid flow to the pre polymerase chain reaction magnet position in the flow channel. The magnetic beads and the nucleic acid are washed with ethanol. The nucleic acid in the polymerase chain reaction chamber is amplified. The magnetic beads and the nucleic acid are separated into a waste stream containing the magnetic beads and a post polymerase chain reaction mix containing the nucleic acid. The reaction mix containing the nucleic acid flows to an analysis unit in the channel for analysis.

  16. Modeling of welded bead profile for rapid prototyping by robotic MAG welding

    Institute of Scientific and Technical Information of China (English)

    CAO Yong; ZHU Sheng; WANG Tao; WANG Wanglong

    2009-01-01

    As a deposition technology, robotic metal active gas(MAG) welding has shown new promise for rapid prototyping (RP) of metallic parts. During the process of metal forming using robotic MAG welding, sectional profile of single-pass welded bead is critical to formed accuracy and quality of metal pans. In this paper, the experiments of single-pass welded bead for rapid prototyping using robotic MAG welding were carried out. The effect of some edge detectors on the cross-sectional edge of welded bead was discussed and curve fitting was applied using leat square fitting. Consequently, the mathematical model of welded bead profile was developed. The experimental results show that good shape could be obtained under suitable welding parameters. Canny operawr is suitable to edge detection of welded bead profile, and the mathematical model of welded bead profile developed is approximately parabola.

  17. Magnetic measurements of suspended functionalised ferromagnetic beads under DC applied fields

    International Nuclear Information System (INIS)

    De Los Santos V, Luis; Llandro, Justin; Lee, Dongwook; Mitrelias, Thanos; Palfreyman, Justin J.; Hayward, Thomas J.; Cooper, Jos; Bland, J.A.C.; Barnes, Crispin H.W.; Arroyo C, Juan L.; Lees, Martin

    2009-01-01

    In this work, a simple technique to obtain the hysteresis loops of magnetic beads (Spherotech Inc.) in liquid suspension is presented. The magnetic measurements were taken in a DC Magnetic Property Measurement System (MPMS-SQUID sensor). Samples were based on ferromagnetic beads (surface-functionalized NH 2 , mean diameter 4.32 μm) prepared in three conditions: dry, suspended in sucrose solution and in suspension after functionalization with fluorophore. Special small containers (1.3 cm long) made of non magnetic plastic were designed to hold the beads in liquid. The results indicate that the bead's remnant magnetization is half of the value at maximum applied field in all cases. However, due to the additional degrees of rotational freedom, beads suspended in a liquid do not present coercivity. The use of ferromagnetic beads and magnetic elements of different architectures for applications in bioassays is also discussed.

  18. Impact of Spherical Frit Beads on Simulated DWPF Slurries

    International Nuclear Information System (INIS)

    SMITH, MICHAEL

    2005-01-01

    It has been shown that the rheological properties of simulated Defense Waste Processing Facility (DWPF) melter feed with the glass former frit as mostly (90 weight percent) solid spherical particles (referred to as beads) were improved as the feed was less viscous as compared to DWPF melter feed that contained the normal irregular shaped frit particles. Because the physical design of the DWPF Slurry Mix Evaporator (SME), Melter Feed Tank (MFT), and melter feed loop are fixed, the impact of changing the rheology might be very beneficial. Most importantly, higher weight percent total solids feed might be processed by reducing the rheological properties (specifically yield stress) of the feed. Additionally, if there are processing problems, such as air entrainment or pumping, these problems might be alleviated by reducing the rheological properties, while maintaining targeted throughputs. Rheology modifiers are chemical, physical, or a combination of the two and can either thin or thicken the rheology of the targeted slurry. The beads are classified as a physical rheological modifier in this case. Even though the improved rheological properties of the feed in the above mentioned DWPF tanks could be quite beneficial, it is the possibility of increased melt rate that is the main driver for the use of beaded glass formers. By improving the rheological properties of the feed, the weight percent solids of the feed could be increased. This higher weight percent solids (less water) feed could be processed faster by the melter as less energy would be required to evaporate the water, and more would be available for the actual melting of the waste and the frit. In addition, the use of beads to thin the feed could possibly allow for the use of a lower targeted acid stoichiometry in the feed preparation process (if in fact acid stoichiometry is being driven by feed rheology as opposed to feed chemistry). Previous work by the Savannah River National Laboratory (SRNL) with the lab

  19. Porphyrin synthesized from cashew nut shell liquid as part of a novel superparamagnetic fluorescence nanosystem

    Energy Technology Data Exchange (ETDEWEB)

    Clemente, C. S.; Ribeiro, V. G. P.; Sousa, J. E. A.; Maia, F. J. N.; Barreto, A. C. H. [Universidade Federal do Ceara, Laboratorio de Produtos e Tecnologia em Processos (LPT) (Brazil); Andrade, N. F. [Universidade Federal do Ceara, Departamento de Fisica (Brazil); Denardin, J. C. [Universidad de Santiago de Chile (USACH), Departamento de Fisica (Chile); Mele, G. [Universita del Salento, Dipartimento di Ingegneria dell' Innovazione (Italy); Carbone, L. [NNL, Istituto Nanoscienze UOS Lecce (Italy); Mazzetto, S. E. [Universidade Federal do Ceara, Laboratorio de Produtos e Tecnologia em Processos (LPT) (Brazil); Fechine, P. B. A., E-mail: fechine@ufc.br [Universidade Federal do Ceara (UFC), Grupo de Quimica de Materiais Avancados (GQMAT), Departamento de Quimica Analitica e Fisico-Quimica (Brazil)

    2013-06-15

    Magnetic Fe{sub 3}O{sub 4} nanoparticles with average size approximately 11 nm were first oleic acid coated to interact with the meso-porphyrin derivative from CNSL. This procedure produced a novel superparamagnetic fluorescent nanosystem (SFN) linked by van der Waals interactions. This system was characterized by transmission electron microscope, infrared spectroscopy, thermogravimetric analysis, magnetic measurements, UV-Vis absorption, and fluorescence emission measurements. These results showed that SFN has good thermal stability, excellent magnetization, and nanosized dimensions ({approx}13 nm). It exhibited emission peaks at 668 and 725 nm with a maximum emission at 467 nm of excitation wavelength. The type of interaction between porphyrin and magnetic nanoparticles allowed to obtain a material with interesting optical properties which might be used as an imaging agent for contrast in cells as well as heterogeneous photocatalysis.

  20. Bio-inspired synthesis and characterization of superparamagnetic particles; Sintese e caracterizacao bioinspirada de particulas superparamagneticas

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Vinicius F., E-mail: vfc_mg@yahoo.com.br [Universidade Federal de Itajuba (UNIFEI), MG (Brazil); Queiroz, Alvaro A.A. [Universidade Federal de Itajuba (UNIFEI), MG (Brazil). Centro de Estudos e Inovacao em Materiais Biofuncionais Avancados

    2012-08-15

    This paper discusses the bio-inspired synthesis of type YFeAl ferrites encapsulated into polyglycerol dendrimers (PGLD) generation 3. The structure and morphological properties of the system YFeAl/PGLD was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The magnetic properties were studied through the techniques of Moessbauer spectroscopy and magnetization. The cytotoxicity of the nanoparticles encapsulated in dendrimers PGLD G3 at the cell membrane was studied against mammalian cell line CHO.K1 measuring the amount of lactate dehydrogenase (LDH) released by the cell damage. Microscopy TEM and XRD analysis indicate that spherical nanoparticles were obtained highly crystalline and monodisperse with size 20 nmsuperparamagnetic behavior of the system YFeAl/PGLD. The cytotoxicity results indicated that YFeAl / PGLD nano system is suitable for use in nano medicine. (author)

  1. Relaxometry and Dephasing Imaging of Superparamagnetic Magnetite Nanoparticles Using a Single Qubit

    Science.gov (United States)

    Schmid-Lorch, Dominik; Häberle, Thomas; Reinhard, Friedemann; Zappe, Andrea; Slota, Michael; Bogani, Lapo; Finkler, Amit; Wrachtrup, Jörg

    2015-08-01

    To study the magnetic dynamics of superparamagnetic nanoparticles we use scanning probe relaxometry and dephasing of the nitrogen-vacancy (NV) center in diamond, characterizing the spin-noise of a single 10-nm magnetite particle. Additionally, we show the anisotropy of the NV sensitivity's dependence on the applied decoherence measurement method. By comparing the change in relaxation (T 1 ) and dephasing (T 2 ) time in the NV center when scanning a nanoparticle over it, we are able to extract the nanoparticle's diameter and distance from the NV center using an Ornstein-Uhlenbeck model for the nanoparticle's fluctuations. This scanning-probe technique can be used in the future to characterize different spin label substitutes for both medical applications and basic magnetic nanoparticle behavior.

  2. Magnetic field strength requirements to capture superparamagnetic nanoparticles within capillary flow

    International Nuclear Information System (INIS)

    Hallmark, B.; Darton, N. J.; James, T.; Agrawal, P.; Slater, N. K. H.

    2010-01-01

    This article reports the development of a model, with supporting experimental data, which can predict the magnitude of the magnetic flux required to capture superparamagnetic nanoparticles flowing through a plastic capillary micro array. The model takes into account the shape of the magnetic field, the magnetically induced aggregation of the nanoparticles and a criterion to determine whether nanoparticles are held at the capillary wall or not. It was found that the model gave a semi-quantitative match to experimental data showing that, once steered out of the core of the fluid flow, nanoparticles could be held at a capillary wall within a weaker region of magnetic field. This result may have implications for the design of magnets for use in magnetic directed therapy in addition to having implications concerning the design of nanoparticle dosage regimes.

  3. 188Re labeled MPEG-modified superparamagnetic nanogels: preparation and preliminary application in mice

    International Nuclear Information System (INIS)

    Sun Hanwen; Gong Peijun; Liu Xiuqing; Hong Jun; Xu Dongmei; Zhang Chunfu; Wang Yongxian; Yao Side

    2005-01-01

    Superparamagnetic poly(acrylamide) magnetic nanogels produced via photochemical method have been developed. After Hoffmann degradation of carbonyl, the nanogels with amino groups, or poly(acrylamide-vinyl amine) magnetic nanogels, were also obtained. And the magnetic nanogels were further modified by methoxy poly(ethylene glycol) (MPEG) for higher dispersibility and stability. The MPEG-modified magnetic nanogels were characterized by X-ray diffraction (XRD), photo correlation spectroscopy (PCS) and scanning electron microscopy (SEM), respectively. The MPEG-modified magnetic nanogels were labeled by 188 Re radiopharmaceuticals and intravenously injected into tails of mice in the presence and absence of a 0.5 T external magnetic field targeted on the bellies. The radioactivity distribution was monitored in vivo. In the absence of magnetic field, the radioactivity was mainly distributed in liver, spleen, kidney, stomach and lung. In the presence of the magnetic field, the radioactivity was mainly accumulated on the targeted point, verifying the magnetically targeted character. (authors)

  4. The correlation between superparamagnetic blocking temperatures and peak temperatures obtained from ac magnetization measurements

    International Nuclear Information System (INIS)

    Madsen, Daniel Esmarch; Moerup, Steen; Hansen, Mikkel Fougt

    2008-01-01

    We study the correlation between the superparamagnetic blocking temperature T B and the peak positions T p observed in ac magnetization measurements for nanoparticles of different classes of magnetic materials. In general, T p = α+βT B . The parameters α and β are different for the in-phase (χ') and out-of-phase (χ'') components and depend on the width σ V of the log-normal volume distribution and the class of magnetic material (ferromagnetic/antiferromagnetic). Consequently, knowledge of both α and β is required if the anisotropy energy barrier KV and the attempt time τ 0 are to be reliably obtained from an analysis based solely on the peak positions

  5. Facile synthesis of polymer-enveloped ultrasmall superparamagnetic iron oxide for magnetic resonance imaging

    International Nuclear Information System (INIS)

    Hong Jun; Xu Dongmei; Yu Jiahui; Gong Peijun; Ma Hongjuan; Yao Side

    2007-01-01

    Ultrasmall superparamagnetic iron oxide (USPIO) with synthetic polymer, based on magnetite core, was synthesized via facile photochemical in situ polymerization. A possible mechanism of photochemical in situ polymerization was proposed. The obtained polymer-enveloped UPSIO was characterized by transmission electron microscopy (TEM), photo-correlation spectroscopy (PCS), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric (TG) analysis and vibrating sampling magnetometer (VSM) measurement. Properties such as ultrasmall particle size, hydrophilicity, strong magnetization and surface characteristics, which are desirable for magnetic resonance imaging (MRI) contrast agents, were evaluated in detail. The resultant USPIO-based MRI contrast agent holds considerable promise in molecular MR tracking, MR immune imaging, cell tracking and targeted intracellular hyperthermia, etc

  6. The Effect of pH and Time on The Stability of Superparamagnetic Maghemite Nanoparticle Suspensions

    Directory of Open Access Journals (Sweden)

    Nurdin Irwan

    2016-01-01

    Full Text Available Maghemite (γ-Fe2O3 nanoparticles have been synthesized using a chemical co-precipitation method. The morphology and particle size is characterized using Transmission Electron Microscopy (TEM, and magnetic characterization using Alternating Gradient Magnetometry (AGM. The stability of the maghemite nanoparticles suspension were studied at different pH and time of storage. Dynamic Light Scattering (DLS and Zeta Potential were conducted to determine the stability of the suspensions. TEM observation showed that the particles size is 9.6 nm and have spherical morphology. The particles showed superparamagnetic behavior with saturation magnetization 25.5 emu/g. The suspensions are stable in the acidic condition at pH 4 and alkaline condition at pH 10. The suspensions remain stable after 4 weeks of storage.

  7. Superparamagnetic adsorbents for high-gradient magnetic fishing of lectins out of legume extracts

    DEFF Research Database (Denmark)

    Heebøll-Nielsen, Anders; Dalkiær, M.; Hubbuch, Jürgen

    2004-01-01

    This work presents the development, testing, and application in high-gradient magnetic fishing of superparamagnetic supports for adsorption of lectins. Various approaches were examined to produce affinity, mixed mode, and hydrophobic charge induction type adsorbents. In clean monocomponent systems...... affinity supports created by direct attachment of glucose or maltose to amine-terminated iron oxide particles could bind concanavalin A at levels of up to approximate to 280 mg g(-1) support with high affinity (approximate to 1 muM dissociation constants). However, the best performance was delivered......-linked adsorbents supplied sufficient competition to dissolved sugars to selectively bind concanavalin A in an extract of jack beans. The dextran-linked supports were employed in a high-gradient magnetic fishing experiment, in which concanavalin A was purified to near homogeneity from a crude, unclarified extract...

  8. Equilibrium magnetization and microstructure of the system of superparamagnetic interacting particles: numerical simulation

    CERN Document Server

    Pshenichnikov, A F

    2000-01-01

    The Monte Carlo method is used to study the equilibrium magnetization of a 3D system of superparamagnetic particles taking into account the steric and dipole-dipole interparticle interactions. Two types of systems are considered: magnetic fluids and solidified ferrocolloids containing randomly spatially distributed particles with negligible energy of magnetic anisotropy. The results of numerical simulations confirm the universality of Langevin susceptibility as a main dimensionless parameter determining the influence of interparticle interactions on the magnetization of the system for moderate values of the aggregation parameter. The obtained results are in good agreement with theoretical and experimental data. At large values of the aggregation parameter, the clustering of particles in magnetic fluids is observed resulting in a reduction of their magnetization as compared to solidified systems. It is shown that the magnetization of solidified systems can be well described by the modified effective field appr...

  9. Cellular uptake of folate-conjugated lipophilic superparamagnetic iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Woo, Kyoungja; Moon, Jihyung; Choi, Kyu-Sil; Seong, Tae-Yeon; Yoon, Kwon-Ha

    2009-01-01

    We prepared five folate-conjugated lipophilic superparamagnetic iron oxide nanoparticles (F 5 -Liposuperparamagnetic iron oxide nanoparticles(SPIONs), 5.5 and 11 nm) and investigated their cellular uptake with KB cells, which is one of the representative folate-receptor over-expressing human epidermoid carcinoma cells, using MRI. The cellular uptake tests with the respective 5.5 and 11 nm F 5 -LipoSPIONs at a fixed particle concentration showed appreciable amount of receptor-mediated uptakes and the specificity was higher in 5.5 nm SPIONs, due to its higher folic acid (FA) density, without inhibition. However, the numbers of the particles taken up under FA inhibition were similar, irrespective of their sizes.

  10. Synthesis of carboxyl superparamagnetic ultrasmall iron oxide (USPIO) nanoparticles by a novel flocculation-redispersion process

    International Nuclear Information System (INIS)

    Cheng Changming; Kou Geng; Wang Xiaoliang; Wang Shuhui; Gu Hongchen; Guo Yajun

    2009-01-01

    We report a novel flocculation-redispersion method to synthesize and purify the biocompatible superparamagnetic ultrasmall iron oxide (USPIO) nanoparticles coated with carboxyl dextran derivative. First, USPIO nanoparticles were synthesized and flocculated to form the large clusters through bridging effect of polyvinyl alcohol (PVA) during coprecipitation process. Then the flocculated USPIO was separated and purified from the solution conveniently through magnetic sedimentation. Finally, USPIO in the clusters were released again and well dispersed through electrostatic repelling effect of citric acid with the aid of ultrasonic. The dispersed carboxyl-functionalized USPIO was conjugated with the monoclonal antibodies. And it has been proved that the antibodies anchored on USPIO still retained their bioactivity after the conjugation. These results implied that the USPIO synthesized have good potential as active targeting molecular probe in biomedical application.

  11. Synthesis and characterization of superparamagnetic nanoparticles obtained by precipitation in inverse microemulsion for biomedical applications

    International Nuclear Information System (INIS)

    Puca Pacheco, Mercedes; Guerrero Aquino, Marco; Tacuri Calanchi, Enrique; Lopez Campos, Raul G.

    2013-01-01

    In this work the preparation of nanoparticles of magnetite by methods of precipitation in inverse microemulsions and the conventional method 'Chemical Co-precipitation' is reported. Magnetite nanoparticles were characterized by X-ray diffraction, Moessbauer spectroscopy and vibrating sample magnetometer (VSM). The results showed that the nanoparticles obtained by the method of precipitation in inverse microemulsion showed a superparamagnetic behavior and had a particle average diameter of 9 nm, while by the conventional method 'Chemical Co-precipitation' were 17 nm. In addition, other benefits observed in the application of the method of precipitation in inverse microemulsion with regard to the conventional method is that it allowed obtaining spheroidal magnetite nanoparticles, monodisperse and with magnetic and chemical properties which might have better results in medical applications. (author)

  12. Equilibrium magnetization and microstructure of the system of superparamagnetic interacting particles: numerical simulation

    International Nuclear Information System (INIS)

    Pshenichnikov, A.F.; Mekhonoshin, V.V.

    2000-01-01

    The Monte Carlo method is used to study the equilibrium magnetization of a 3D system of superparamagnetic particles taking into account the steric and dipole-dipole interparticle interactions. Two types of systems are considered: magnetic fluids and solidified ferrocolloids containing randomly spatially distributed particles with negligible energy of magnetic anisotropy. The results of numerical simulations confirm the universality of Langevin susceptibility as a main dimensionless parameter determining the influence of interparticle interactions on the magnetization of the system for moderate values of the aggregation parameter. The obtained results are in good agreement with theoretical and experimental data. At large values of the aggregation parameter, the clustering of particles in magnetic fluids is observed resulting in a reduction of their magnetization as compared to solidified systems. It is shown that the magnetization of solidified systems can be well described by the modified effective field approximation within the whole investigated range of parameters

  13. Cellular uptake of folate-conjugated lipophilic superparamagnetic iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Kyoungja [Nano-Materials Research Center, Korea Institute of Science and Technology, P. O. Box 131, Cheongryang, Seoul 130-650 (Korea, Republic of)], E-mail: kjwoo@kist.re.kr; Moon, Jihyung [Nano-Materials Research Center, Korea Institute of Science and Technology, P. O. Box 131, Cheongryang, Seoul 130-650 (Korea, Republic of); Department of Materials Science and Engineering, Korea University, 5-1, Anam-Dong, Sungbook-Ku, Seoul, 136-713 (Korea, Republic of); Choi, Kyu-Sil [Division of Molecular Imaging, Samsung Biomedical Research Institute, Samsung Medical Center, 50 Ilwon-Dong, Kangnam-Ku, Seoul 135-710 (Korea, Republic of); Seong, Tae-Yeon [Department of Materials Science and Engineering, Korea University, 5-1, Anam-Dong, Sungbook-Ku, Seoul, 136-713 (Korea, Republic of); Yoon, Kwon-Ha [Institute for Radiological Imaging Science, Wonkwang University School of Medicine, 344-2, Shinyong, Iksan, Jeonbuk 570-749 (Korea, Republic of)

    2009-05-15

    We prepared five folate-conjugated lipophilic superparamagnetic iron oxide nanoparticles (F{sub 5}-Liposuperparamagnetic iron oxide nanoparticles(SPIONs), 5.5 and 11 nm) and investigated their cellular uptake with KB cells, which is one of the representative folate-receptor over-expressing human epidermoid carcinoma cells, using MRI. The cellular uptake tests with the respective 5.5 and 11 nm F{sub 5}-LipoSPIONs at a fixed particle concentration showed appreciable amount of receptor-mediated uptakes and the specificity was higher in 5.5 nm SPIONs, due to its higher folic acid (FA) density, without inhibition. However, the numbers of the particles taken up under FA inhibition were similar, irrespective of their sizes.

  14. Superparamagnetic Bifunctional Bisphosphonates Nanoparticles: A Potential MRI Contrast Agent for Osteoporosis Therapy and Diagnostic

    Directory of Open Access Journals (Sweden)

    Y. Lalatonne

    2010-01-01

    Full Text Available A bone targeting nanosystem is reported here which combined magnetic contrast agent for Magnetic Resonance Imaging (MRI and a therapeutic agent (bisphosphonates into one drug delivery system. This new targeting nanoplatform consists of superparamagnetic γFe2O3 nanoparticles conjugated to 1,5-dihydroxy-1,5,5-tris-phosphono-pentyl-phosphonic acid (di-HMBPs molecules with a bisphosphonate function at the outer of the nanoparticle surface for bone targeting. The as-synthesized nanoparticles were evaluated as a specific MRI contrast agent by adsorption study onto hydroxyapatite and MRI measurment. The strong adsorption of the bisphosphonates nanoparticles to hydroxyapatite and their use as MRI T2∗ contrast agent were demonstrated. Cellular tests performed on human osteosarcoma cells (MG63 show that γFe2O3@di-HMBP hybrid nanomaterial has no citoxity effect in cell viability and may act as a diagnostic and therapeutic system.

  15. Current status of superparamagnetic iron oxide contrast agents for liver magnetic resonance imaging.

    Science.gov (United States)

    Wang, Yi-Xiang J

    2015-12-21

    Five types of superparamagnetic iron oxide (SPIO), i.e. Ferumoxides (Feridex(®) IV, Berlex Laboratories), Ferucarbotran (Resovist(®), Bayer Healthcare), Ferumoxtran-10 (AMI-227 or Code-7227, Combidex(®), AMAG Pharma; Sinerem(®), Guerbet), NC100150 (Clariscan(®), Nycomed,) and (VSOP C184, Ferropharm) have been designed and clinically tested as magnetic resonance contrast agents. However, until now Resovist(®) is current available in only a few countries. The other four agents have been stopped for further development or withdrawn from the market. Another SPIO agent Ferumoxytol (Feraheme(®)) is approved for the treatment of iron deficiency in adult chronic kidney disease patients. Ferumoxytol is comprised of iron oxide particles surrounded by a carbohydrate coat, and it is being explored as a potential imaging approach for evaluating lymph nodes and certain liver tumors.

  16. Mechanism of Dimercaptosuccinic Acid Coated Superparamagnetic Iron Oxide Nanoparticles with Human Serum Albumin.

    Science.gov (United States)

    Zhao, Lining; Song, Wei; Wang, Jing; Yan, Yunxing; Chen, Jiangwei; Liu, Rutao

    2015-12-01

    To research the mechanism of dimercaptosuccinic acid coated-superparamagnetic iron oxide nanoparticles (SPION) with human serum albumin (HSA), the methods of spectroscopy, molecular modeling calculation, and calorimetry were used in this paper. The inner filter effect of the fluorescence intensity was corrected to obtain the accurate results. Ultraviolet-visible absorption and circular dichroism spectra reflect that SPION changed the secondary structure with a loss of α-helix and loosened the protein skeleton of HSA; the activity of the protein was also affected by the increasing exposure of SPION. Fluorescence lifetime measurement indicates that the quenching mechanism type of this system was static quenching. The isothermal titration calorimetry measurement and molecular docking calculations prove that the predominant force of this system was the combination of Van der Waals' force and hydrogen bonds. © 2015 Wiley Periodicals, Inc.

  17. Colloidal stability of superparamagnetic iron oxide nanoparticles in the central nervous system: a review.

    Science.gov (United States)

    Champagne, Pierre-Olivier; Westwick, Harrison; Bouthillier, Alain; Sawan, Mohamad

    2018-06-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) consist of nanosized metallic-based particles with unique magnetic properties. Their potential in both diagnostic and therapeutic applications in the CNS is at the source of an expanding body of the literature in recent years. Colloidal stability of nanoparticles represents their ability to resist aggregation and is a central aspect for the use of SPION in biological environment such as the CNS. This review gives a comprehensive update of the recent developments and knowledge on the determinants of colloidal stability of SPIONs in the CNS. Factors leading to aggregate formation and the repercussions of colloidal instability of SPION are reviewed in detail pertaining to their use in the CNS.

  18. Detection of the immunologic rejection after xeno-islet transplantation: a study by MR imaging enhanced with superparamagnetic iron oxide marking CD4+ T cell antibody

    International Nuclear Information System (INIS)

    Nie Wei; Tang Yiya; Rong Pengfei; Ye Bin; Ye Zheng; Tong Qiongjuan; Wang Wei

    2008-01-01

    Objective: To evaluate the feasibility of the diagnosis of the early immunologic rejection after xeno-islet transplantation by MR imaging enhanced with superparamagnetic iron oxide (SPIO) marking CD4 + T cell antibody. Methods: Two thousand neonatal porcine islets (NPI)were transplanted under the left renal capsule of BALB/C nude mice. When the grafts could be observed by MRI, 10 7 human PBMC was intraperitoneal injected to nude mouse models to reconstitute the human immunologic system, 20 mice were reconstituted. Before and 3,7,14 days after reconstitution of human immunologic system on BALB/C nude mice, MRI imaging was performed half an hour after intravenous injection of nano-immunomagnetic beads via vena caudatis to observe the grafts' MRI signal. BALB/C nude mice were sacrificed after MRI scanning immediately, the histopathologic examination was assessed on grafts, the results were compared with MRI results. And calculate the sensitivity, specificity, Youden index number and coincidence of the MRI for immunologic rejection. Results: Grafts can be observed by MRI 3 weeks after islet cell transplantation (before immunologic rejection modeling), there is no abnormal MRI signal detected in nude mice' graft region after microbeads injected. Seven days after building of immunologic rejection model, MRI hypo-signal in graft site is shown in the T 2 WI sequence after nano-bioprober injected. Histopathologic assessments were employed on grafts in nude mice immediately (HE and immunohistochemistry staining), the results shown that there are a lot of T lymphocyts infiltrated in graft region, implying the occurrence of immunologic rejection. And the sensitivity, specificity, Youden index number and coincidence is: (72.96±0.24)%, 100%, 0.73±0.24, (88.46±0.13)% respectively. The correct Kappa between the MRI and the imunohistochemistry staining was 0.76. Conclusion: The cellular immunological rejection to xeno-islet grarts can be assessed with nano-bioprobe with anti-CD4

  19. SparseBeads data: benchmarking sparsity-regularized computed tomography

    Science.gov (United States)

    Jørgensen, Jakob S.; Coban, Sophia B.; Lionheart, William R. B.; McDonald, Samuel A.; Withers, Philip J.

    2017-12-01

    Sparsity regularization (SR) such as total variation (TV) minimization allows accurate image reconstruction in x-ray computed tomography (CT) from fewer projections than analytical methods. Exactly how few projections suffice and how this number may depend on the image remain poorly understood. Compressive sensing connects the critical number of projections to the image sparsity, but does not cover CT, however empirical results suggest a similar connection. The present work establishes for real CT data a connection between gradient sparsity and the sufficient number of projections for accurate TV-regularized reconstruction. A collection of 48 x-ray CT datasets called SparseBeads was designed for benchmarking SR reconstruction algorithms. Beadpacks comprising glass beads of five different sizes as well as mixtures were scanned in a micro-CT scanner to provide structured datasets with variable image sparsity levels, number of projections and noise levels to allow the systematic assessment of parameters affecting performance of SR reconstruction algorithms6. Using the SparseBeads data, TV-regularized reconstruction quality was assessed as a function of numbers of projections and gradient sparsity. The critical number of projections for satisfactory TV-regularized reconstruction increased almost linearly with the gradient sparsity. This establishes a quantitative guideline from which one may predict how few projections to acquire based on expected sample sparsity level as an aid in planning of dose- or time-critical experiments. The results are expected to hold for samples of similar characteristics, i.e. consisting of few, distinct phases with relatively simple structure. Such cases are plentiful in porous media, composite materials, foams, as well as non-destructive testing and metrology. For samples of other characteristics the proposed methodology may be used to investigate similar relations.

  20. Butyl acetate synthesis using immobilized lipase in calcium alginate beads

    International Nuclear Information System (INIS)

    Mohd Zulkhairi Abdul Rahim; Lee, Pat M.; Lee, Kong H.

    2008-01-01

    The esterification reaction of acetic acid and n-butanol using immobilized lipase encapsulated in calcium alginate beads (Lipase - CAB) and in chitosan coated calcium alginate beads (Lipase-CCAB) in n-hexane under mild reaction conditions were studied. Effects of temperature and substrate concentration (acetic acid and n-butanol) using Lipase - CAB, Lipase - CCAB and free lipase on the esterification reaction and their thermal stability towards esterification reaction were investigated. Results of temperature studies showed that the butyl acetate conversion increased with increase of temperature and reached the highest yield of about 70% around 50 degree Celsius for both immobilized systems but the yield of product catalyzed by free enzyme decreased as temperature was increased. Thermal stabilities studies showed that the Lipase-CCAB and Lipase-CAB were stable throughout the temperature range of 30-60 degree Celsius. However, free lipase became less stable at temperatures higher than 50 degree Celsius. The substrates, n-butanol and acetic acid exerted different effects on the esterification reaction and the reaction was favoured by higher acetic acid concentration than butanol. Kinetics parameters, Km and Vmax values for both substrates and the specific activities of the three enzyme system were also determined. The beads morphology was examined using SEM. Batch-wise operational stability studies for both immobilized systems demonstrated that the immobilized lipase performed better in the batch wise reactor system than the continuous bioreactor system and that the immobilized lipase remained active for at least 5 cycles of batch wise esterification reactions. (author)

  1. Microscope-controlled glass bead blasting: a new technique

    Directory of Open Access Journals (Sweden)

    Peter Kotschy

    2011-01-01

    Full Text Available Peter Kotschy1, Sascha Virnik2, Doris Christ3, Alexander Gaggl21Private Practice, Vienna, Austria; 2Department of Oral and Maxillofacial Surgery, Central Hospital, Klagenfurt, Austria; 3Klagenfurt, AustriaObjective: The aim of periodontal therapy is the healing of periodontal inflammation; the protection of the attachment and the alveolar bone; and the regeneration of the periodontal structures. In the therapy of periodontitis, supra- and subgingival scaling and root planing plays a main role. The procedure described combines perfect root cleaning without scaling and root planing and minimal invasive periodontal surgery without a scalpel.Material and methods: Glass beads of 90 µm were used with the kinetic preparation unit PrepStart® under a pressure of 0.5–5 bar. This technique was practised only under visual control using the OPMI® PRO Magis microscope. Seven examinations were carried out at baseline after 3, 6, 12, 18, 24, and 36 months.Results: Time shows a statistically significant influence on all of the considered target variables (P < 0.0001 for all. As the according estimate is negative, probing depth decreases over time. The major decrease seems to be during the first 6 months. Considering probing depth, plaque on the main effect root shows significant influence (again, P < 0.0001 for all. Observations with high probing depth at the beginning were faster than those with low probing depth. The same characteristic appears by attachment level. Patients with more loss of attachment show more gain.Conclusions: Using microscope-controlled glass bead blasting results in a perfectly clean root surface using visual control (magnification 20×. Microscope-controlled glass bead blasting is therefore a good alternative to periodontal surgery.Keywords: periodontal therapy, microscope, periodontitis

  2. Salt and divalent cations affect the flexible nature of the natural beaded chromatin structure

    DEFF Research Database (Denmark)

    Christiansen, Gunna; Griffith, J

    1977-01-01

    Cl or 0.6M NaCL, and is compact in 0.01 M NaCl solutions if histone H 1 is present. Even high concentrations of urea did not alter the fundamental beaded structure, consisting of 110A beads of 200 base pair content, each joined by thin DNA bridges of 50 base pairs. The physical bead observed by EM...

  3. Fabrication of micromagnetic beads with molecular recognition/electron-transfer peptides for the sensing of ovalbumin

    Energy Technology Data Exchange (ETDEWEB)

    Sugawara, Kazuharu, E-mail: kzsuga@maebashi-it.ac.jp [Maebashi Institute of Technology, Gunma, 371-0816 (Japan); Kuramitz, Hideki [Department of Environmental Biology and Chemistry, Graduate School of Science and Engineering for Research, University of Toyama, Toyama, 930-8555 (Japan); Shinohara, Hiroki [Maebashi Institute of Technology, Gunma, 371-0816 (Japan)

    2017-03-15

    Electrochemical sensing of ovalbumin (OVA) was performed using magnetic beads with OVA recognition (RNRCKGTDVQAW)/electron-transfer (YYYYC) peptides. The focus of this study was to construct a highly sensitive and regenerative tool for OVA detection based on the interaction between a protein and peptide-1(RNRCKGTDVQAWYYYYC). The peptide-1 was introduced to the bead through four types of cross-linking reagents. Magnetic beads of different sizes with N-(6-maleimidocaproyloxy)sulfosuccinimide (Sulfo-EMCS) were also prepared. An oxidation peak due to tyrosine residues at 0.65 V depended on the distance of the electron-transfer peptide from the bead surface and on the surface area of the magnetic beads that contacted the electrode surface. The response of the electro-transfer peptide moiety was decreased because the protein was accumulated via the recognition peptide on the beads. When using Sulfo-EMCS and beads that were 6.0–6.9 μm in diameter, the calibration curve of OVA was linear and ranged from 8.0 × 10{sup −13} to 2.0 × 10{sup −11} M. To regenerate the magnetic beads, the measurements were achieved after removal of the OVA using a denaturing reagent. When OVA was added to fetal bovine serum containing a complex matrix, OVA was recovered at a rate of 98–100%. Consequently, these magnetic beads could be a powerful tool for the sensing of OVA in real samples. - Highlights: • Ovalbumin recognition/electron-transfer peptides were immobilized on magnetic beads. • The accumulation of the protein through the peptides on the beads caused the change of electrode response. • The magnetic beads could be reused for sensing of ovalbumin.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    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 (Fe 3 O 4 ) (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. - Highlights: • Homogeneous field yields an aggregation of particles along the lines of the field. • Additional electromagnet field rotates the

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

    Energy Technology Data Exchange (ETDEWEB)

    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 (Fe{sub 3}O{sub 4}) (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. - Highlights: • Homogeneous field yields an aggregation of particles along the lines of the field. • Additional electromagnet field rotates the

  6. Synthesis of superparamagnetic δ-FeOOH nanoparticles by a chemical method

    Energy Technology Data Exchange (ETDEWEB)

    Nishida, Naoki, E-mail: nnishida@rs.tus.ac.jp [Department of Chemistry, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan); Amagasa, Shota [Department of Chemistry, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan); Kobayashi, Yoshio [Department of Engineering Science, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585 (Japan); Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Yamada, Yasuhiro [Department of Chemistry, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan)

    2016-11-30

    Highlights: • The spherical δ-FeOOH nanoparticles were synthesized by a chemical reaction of FeCl{sub 2}. • The δ-FeOOH nanoparticles showed superparamagnetic behavior. • A mixture of Fe{sub 3}O{sub 4} and Fe(OH){sub 2} were rapidly oxidized into δ-FeOOH nanoparticles. - Abstract: δ-FeOOH nanoparticles were synthesized via the oxidation of precipitates obtained from the reaction of FeCl{sub 2} and N{sub 2}H{sub 4} in the presence of sodium tartrate and gelatin in an alkaline condition. These δ-FeOOH particles were subsequently examined using transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), powder X-ray diffraction (XRD), Mössbauer spectroscopy, and superconducting quantum interference device (SQUID) assessment. The average size of the δ-FeOOH nanoparticles was below 10 nm, and these particles exhibited superparamagnetic behavior as a result of this small size. The precursors of the δ-FeOOH nanoparticles were also characterized as a means of elucidating the reaction mechanism. Precipitates prior to oxidation upon rinsing with water and ethanol were analyzed by obtaining XRD patterns and Mössbauer spectra of wet and frozen samples, respectively. The precipitates obtained by the reaction of FeCl{sub 2} and N{sub 2}H{sub 4} were found to consist of a mixture of Fe{sub 3}O{sub 4} and Fe(OH){sub 2}, and it is believed that these species then rapidly oxidized into δ-FeOOH nanoparticles.

  7. Efficient synthesis of superparamagnetic magnetite nanoparticles under air for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Saxena, Namita, E-mail: saxenanamita@yahoo.com [School of Nano Sciences, Central University of Gujarat, Gandhinagar 382030 (India); Singh, Man, E-mail: mansingh50@hotmail.com [School of Chemical Sciences, Central University of Gujarat, Gandhinagar 382030 (India)

    2017-05-01

    The facile co-precipitation process of synthesising Superparamagnetic Iron Oxide Nanoparticles (SPIONs) especially magnetite was investigated and simplified, to develop a reproducible and scaled up synthesis process under air, for producing particles with enhanced percentage of magnetite, thus eliminating the crucial and complicated need of using the inert atmosphere. Presence of magnetite was confirmed by XRD, TEM, and Raman spectroscopy. Efficiency of synthesising magnetite was increased up to approx. ∼58 wt%, under air with no other phases but maghemite present. Alkali concentration was optimised, and particles with better magnetisation values were synthesised. The approximate weight percentage of magnetite was calculated using the simple and rapid XRD peak deconvolution method. Higher pH values from 13 to14 were investigated in the study while alkali concentration was varied from 0.5 to 4 M. 1Molar NaOH with a final pH of 13.4 was found to be optimum. Well crystallised particles with approx. 6–12 nm size, narrow size distribution and cubo-spheroidal shape were synthesised. Particles were Superparamagnetic with high values of saturation magnetisation of up to 68 emu/g and negligible values of remanence and coercivity. A reaction yield of up to 62% was obtained. Hydrophilic coated particles were produced in a single, one step facile process for biomedical applications, using optimised parameters of pH and alkali concentration obtained in the study. Single domain particles with good magnetisation formed stable aqueous dispersions. FTIR, UV-Visible and DLS were used to confirm the coating and dispersion stabilities of the particles. These particles have the requisite properties required for application in different biomedical fields.

  8. Different approaches to analyze the dipolar interaction effects on diluted and concentrated granular superparamagnetic systems

    Energy Technology Data Exchange (ETDEWEB)

    Moscoso-Londoño, O., E-mail: omoscoso@ifi.unicamp.br [Instituto de Física ‘Gleb Wataghin’, Universidade Estadual de Campinas (UNICAMP), CEP13083-859 Campinas, São Paulo (Brazil); Tancredi, P. [Laboratorio de Sólidos Amorfos, INTECIN, Facultad de Ingeniería, Universidad de Buenos Aires (UBA), CONICET, C1063ACV Buenos Aires (Argentina); Muraca, D. [Instituto de Física ‘Gleb Wataghin’, Universidade Estadual de Campinas (UNICAMP), CEP13083-859 Campinas, São Paulo (Brazil); Centro de Ciencias Naturais e Humanas, Universidade Federal do ABC (UFABC), Av. Dos Estados, 5001, Santo André, SP (Brazil); Mendoza Zélis, P.; Coral, D.; Fernández van Raap, M.B. [Instituto de Física, Universidad Nacional de La Plata (UNLP), CONICET, CC.67, 1900 La Plata, Buenos Aires (Argentina); Wolff, U.; Neu, V.; Damm, C. [IFW Dresden, Leibniz Institute for Solid State and Materials Research, Dresden, Helmholtzstrasse 20, 01069 Dresden (Germany); Oliveira, C.L.P. de [Instituto de Física, Universidade de São Paulo, São Paulo 05314970 (Brazil); Pirota, K.R. [Instituto de Física ‘Gleb Wataghin’, Universidade Estadual de Campinas (UNICAMP), CEP13083-859 Campinas, São Paulo (Brazil); and others

    2017-04-15

    Controlled magnetic granular materials with different concentrations of magnetite nanoparticles immersed in a non-conducting polymer matrix were synthesized and, their macroscopic magnetic observables analyzed in order to advance towards a better understanding of the magnetic dipolar interactions and its effects on the obtained magnetic parameters. First, by means of X-ray diffraction, transmission electron microscopy, small angle X-ray scattering and X-ray absorption fine structure an accurate study of the structural properties was carried out. Then, the magnetic properties were analyzed by means of different models, including those that consider the magnetic interactions through long-range dipolar forces as: the Interacting Superparamagnetic Model (ISP) and the Vogel-Fulcher law (V-F). In systems with larger nanoparticle concentrations, magnetic results clearly indicate that the role played by the dipolar interactions affects the magnetic properties, giving rise to obtaining magnetic and structural parameters without physical meaning. Magnetic parameters as the effective anisotropic constant, magnetic moment relaxation time and mean blocking temperature, extracted from the application of the ISP model and V-F Law, were used to simulate the zero-field-cooling (ZFC) and field-cooling curves (FC). A comparative analysis of the simulated, fitted and experimental ZFC/FC curves suggests that the current models depict indeed our dilute granular systems. Notwithstanding, for concentrated samples, the ISP model infers that clustered nanoparticles are being interpreted as single entities of larger magnetic moment and volume, effect that is apparently related to a collective and complex magnetic moment dynamics within the cluster. - Highlights: • Nanoparticle architecture into matrices determines the composite magnetic response. • Magnetically diluted or compacted systems are useful to study magnetism at nanoscale. • Particle aggregation into the matrices was examined

  9. The force analysis for superparamagnetic nanoparticles-based gene delivery in an oscillating magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Jiajia [State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, No. 28 Xianning West Road, Xi’an, Shaanxi Province 710049 (China); Shi, Zongqian, E-mail: zqshi@mail.xjtu.edu.cn [State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, No. 28 Xianning West Road, Xi’an, Shaanxi Province 710049 (China); Jia, Shenli [State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, No. 28 Xianning West Road, Xi’an, Shaanxi Province 710049 (China); Zhang, Pengbo [Department of Anesthesiology, Second Affiliated Hospital of Xi’an Jiaotong University School of Medicine, No.157 West 5 Road, Xi’an, Shaanxi Province 710004 (China)

    2017-04-01

    Due to the peculiar magnetic properties and the ability to function in cell-level biological interaction, superparamagnetic nanoparticles (SMNP) have been being the attractive carrier for gene delivery. The superparamagnetic nanoparticles with surface-bound gene vector can be attracted to the surface of cells by the Kelvin force provided by external magnetic field. In this article, the influence of the oscillating magnetic field on the characteristics of magnetofection is studied in terms of the magnetophoretic velocity. The magnetic field of a cylindrical permanent magnet is calculated by equivalent current source (ECS) method, and the Kelvin force is derived by using the effective moment method. The results show that the static magnetic field accelerates the sedimentation of the particles, and drives the particles inward towards the axis of the magnet. Based on the investigation of the magnetophoretic velocity of the particle under horizontally oscillating magnetic field, an oscillating velocity within the amplitude of the magnet oscillation is observed. Furthermore, simulation results indicate that the oscillating amplitude plays an important role in regulating the active region, where the particles may present oscillating motion. The analysis of the magnetophoretic velocity gives us an insight into the physical mechanism of the magnetofection. It's also helpful to the optimal design of the magnetofection system. - Highlights: • We compare the results of the ECS method and FEA method with the commercial software, Ansys. • We analyze the physic mechanism of the oscillating motion of the particles in the presence of an oscillating magnet. • We discuss the influence of the oscillating amplitude of the magnet on the behavior of the particle.

  10. High blocking temperature in SnO{sub 2} based super-paramagnetic diluted magnetic semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Mounkachi, O., E-mail: o.mounkachi@mascir.com [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble cedex 9 (France); Salmani, E. [LMPHE, associé au CNRST (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco); El Moussaoui, H. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); Masrour, R. [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, Safi (Morocco); Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble cedex 9 (France); Hamedoun, M. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); Ez-Zahraouy, H. [LMPHE, associé au CNRST (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco); Hlil, E.K. [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble cedex 9 (France); Benyoussef, A. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); LMPHE, associé au CNRST (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco)

    2014-11-25

    Highlights: • Simple doping, (Sn,Fe)O{sub 2} exhibits a soft ferromagnetism at low temperature. • High blocking temperature was observed for Cu doped (Sn,Fe)O{sub 2} nanocrystalline. • Experimental results are confirmed by ab initio calculations. - Abstract: (Fe,Cu)-doped SnO{sub 2} nanocrystals was synthesized using the co-precipitation method. Magnetic Properties Measurement System (MPMS) revealed that for simple doping, Fe-doped SnO{sub 2} soft ferromagnetism at low temperature appears, while the ferromagnetic phase is stable at temperature higher than room temperature for Cu co-doping element. The ferromagnetism is significantly enhanced by the Cu addition to Fe-doped SnO{sub 2}, according to the ZFC and FC magnetizations and the hysteresis loops. The evidences for the existence of superparamagnetism are characterized and high blocking temperature super-paramagnetism in (Fe,Cu)-doped SnO{sub 2} nanocrystals was observed. Based on first-principles calculations, we have investigated electronic structures and magnetic properties of Fe-doped SnO{sub 2} and (Fe,Cu)-doped SnO{sub 2} with and without defect with LDA and LDA-SIC approximations. The results suggest that the oxygen vacancies (V{sub O}) play a critical role in the activation of ferromagnetism in Fe doped SnO{sub 2}. For (Fe,Cu)-doped SnO{sub 2} the results exhibit that Cu strongly influences on the magnetic properties of these doped systems which are in good agreement with the experimental observations. Electronic structure show that the presence of Cu promote the ferromagnetic bound magnetic polaron interaction through the carriers introduce by d (Cu)

  11. Preparation, Characterization and Tests of Incorporation in Stem Cells of Superparamagnetic Iron Oxide

    International Nuclear Information System (INIS)

    Haddad, P S; Britos, T N; Li, L M; Li, L D S

    2015-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) have been produced and used as contrast-enhancing agents in magnetic resonance imaging (MRI) for diagnostic use in a wide range of maladies including cardiovascular, neurological disorders, and cancer. The reasons why these SPIONs are attractive for medical purposes are based on their important and unique features. The large surface area of the nanoparticles and their manipulation through an external magnetic field are features that allow their use for carrying a large number of molecules such as biomolecules or drugs. In this scenario, the present work reports on the synthesis and characterization of SPIONs and in vitro MRI experiments to increase their capacity as probes for MRI applications on stem cells therapy. Initially, the SPIONs were prepared through the co-precipitation method using ferrous and ferric chlorides in acidic solution. The SPIONs were coated with two thiolmolecules such as mercaptosuccinic acid (MSA) and cysteine (Cys) (molar ratio SPIONs:ligand = 1:20), leading to the formation of a stable aqueous dispersion of thiolated nanoparticles (SH-SPIONs). The SH-SPIONs were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). The results showed that the SH-SPIONs have a mean diameter of 14 nm and display superparamagnetic behavior at room temperature. Preliminary tests of incorporation of SH-SPIONs were evaluated stem cells. The results showed that the thiolated nanoparticles have no toxic effects for stem cells and successfully internalized and enhance the contrast in MRI. (paper)

  12. A facile method to prepare superparamagnetic iron oxide and hydrophobic drug-encapsulated biodegradable polyurethane nanoparticles.

    Science.gov (United States)

    Cheng, Kuo-Wei; Hsu, Shan-Hui

    2017-01-01

    Superparamagnetic iron oxide nanoparticles (SPIO NPs) have a wide range of biomedical applications such as in magnetic resonance imaging, targeting, and hyperthermia therapy. Aggregation of SPIO NPs can occur because of the hydrophobic surface and high surface energy of SPIO NPs. Here, we developed a facile method to encapsulate SPIO NPs in amphiphilic biodegradable polymer. Anionic biodegradable polyurethane nanoparticles (PU NPs) with ~35 nm size and different chemistry were prepared by waterborne processes. SPIO NPs were synthesized by chemical co-precipitation. SPIO NPs were then added to the aqueous dispersion of PU NPs, followed by application of high-frequency (~20 kHz) ultrasonic vibration for 3 min. This method rendered SPIO-PU hybrid NPs (size ~110 nm) suspended in water. SPIO-PU hybrid NPs contained ~50-60 wt% SPIO and retained the superparamagnetic property (evaluated by a magnetometer) as well as high contrast in magnetic resonance imaging. SPIO-PU NPs also showed the ability to provide cell hyperthermic treatment. Using the same ultrasonic method, hydrophobic drug (Vitamin K3 [VK3]) or (9-(methylaminomethyl) anthracene [MAMA]) could also be encapsulated in PU NPs. The VK3-PU or MAMA-PU hybrid NPs had ~35 nm size and different release profiles for PUs with different chemistry. The encapsulation efficiency for VK3 and MAMA was high (~95%) without burst release. The encapsulation mechanism may be attributed to the low glass transition temperature (Tg) and good mechanical compliance of PU NPs. The new encapsulation method involving waterborne biodegradable PU NPs is simple, rapid, and effective to produce multimodular NP carriers.

  13. [Development of new magnetic bead separation and purification instrument].

    Science.gov (United States)

    Xu, Yingyuan; Chen, Yi

    2014-05-01

    The article describes the development of new magnetic bead separation and purification instrument. The main application of the instrument is to capture tubercle bacillus from sputum. It is a pretreatment instrument and provides a new platform to help doctors to diagnose bacillary phthisis. Not only could it be used for tubercle bacillus capturing, but also for gene, protein and cell separating and purification. Because the controller of the instrument is 16-bit single chip microcomputer, the cost could be greatly reduced and it will be widely used in China.

  14. PRELIMINARY STUDY ON RETRO-REFLECTIVE COATED PAPER BASED ON MICRO-GLASS BEADS

    Institute of Scientific and Technical Information of China (English)

    YulongWang; ChuanshanZhao; TaoZhang

    2004-01-01

    High-reflectivity micro-glass bead, as a kind ofretro-reflective material, is widely used in reflectivefabric or film and other reflective coatings. But it israrely used in coated paper. The retro-reflectivetheory of micro-bead is described. Also the effect ofsize of micro-bead, dosage of binder and differentcolor layers on reflective properties of coated paperare discussed in this article. The results show that itsretro-reflective efficiency is good, equally toreflective fabric or film when the micro-glass bead isused in coated paper.

  15. Effect of formulation of alginate beads on their mechanical behavior and stiffness

    Institute of Scientific and Technical Information of China (English)

    Eng-Seng Chan; Tek-Kaun Lim; Wan-Ping Voo; Ravindra Pogaku; Beng Ti Tey; Zhibing Zhang

    2011-01-01

    The aim of this work was to determine the effect of formulation of alginate beads on their mechanical behavior and stiffness when compressed at high speed. The alginate beads were formulated using different types and concentrations of alginate and gelling cations and were produced using an extrusiondripping method. Single wet beads were compressed at a speed of 40 mm/min, and their elastic limits were investigated, and the corresponding force versus displacement data were obtained. The Young's moduli of the beads were determined from the force versus displacement data using the Hertz's contact mechanics theory. The alginate beads were found to exhibit plastic behavior when they were compressed beyond 50% with the exception of copper-alginate beads for which yield occured at lower deformation.Alginate beads made of higher guluronic acid contents and gelling cations of higher chemical affinity were found to have greater stiffness. Increasing the concentration of alginate and gelling ions also generated a similar effect. At such a compression speed, the values of Young's modulus of the beads were found to be in the range between 250 and 900 kPa depending on the bead formulation.

  16. PRELIMINARY STUDY ON RETRO-REFLECTIVE COATED PAPER BASED ON MICRO-GLASS BEADS

    Institute of Scientific and Technical Information of China (English)

    Yulong Wang; Chuanshan Zhao; Tao Zhang

    2004-01-01

    High-reflectivity micro-glass bead, as a kind of retro-reflective material, is widely used in reflective fabric or film and other reflective coatings. But it is rarely used in coated paper. The retro-reflective theory of micro-bead is described. Also the effect of size of micro-bead, dosage of binder and different color layers on reflective properties of coated paper are discussed in this article. The results show that its retro-reflective efficiency is good, equally to reflective fabric or film when the micro-glass bead is used in coated paper.

  17. Enhancing the antimony sorption properties of nano titania-chitosan beads using epichlorohydrin as the crosslinker.

    Science.gov (United States)

    Nishad, Padala Abdul; Bhaskarapillai, Anupkumar; Velmurugan, Sankaralingam

    2017-07-15

    Antimony is classified as a pollutant of priority importance by USEPA. We have earlier reported the synthesis of nano-titania impregnated epichlorohydrin crosslinked chitosan (TA-Cts-Epi) beads, in a format suitable for large scale applications with high sorption capacity for antimony. To understand the sorption mechanism, and to fine tune the bead composition, the effect of crosslinking density on the swelling and sorption properties of the beads was investigated in detail. Epichlorohydrin effected significant changes in physical and sorption properties of the beads. The antimony sorption capacity of the TA-Cts-Epi beads prepared by crosslinking 0.3g non-crosslinked titania-chitosan beads (TA-Cts-NCL) with 6.4mmol epichlorohydrin was 493μmol/g, while those crosslinked with 0.64mmol showed a capacity of 133μmol/g. Whereas, TA-Cts-NCL beads showed a capacity of 75μmol/g. The increase in uptake capacity with increase in crosslinking demonstrated the active involvement of the epichlorohydrin moieties in antimony binding leading to enhanced sorption. Apart from altering the stability, swelling behaviour and sorption kinetics of the beads, crosslinking significantly increased the uptake of the anionic species via electrostatic interactions. Epichlorohydrin crosslinked chitosan beads prepared without TiO 2 also showed similar behaviour. The results demonstrated the involvement of chitosan, TiO 2 and epichlorohydrin in sorption. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. On-chip measurements of Brownian relaxation vs. concentration of 40nm magnetic beads

    DEFF Research Database (Denmark)

    Østerberg, Frederik Westergaard; Rizzi, Giovanni; Hansen, Mikkel Fougt

    2012-01-01

    We present on-chip Brownian relaxation measurements on a logarithmic dilution series of 40 nm beads dispersed in water with bead concentrations between 16 mu g/ml and 4000 mu g/ml. The measurements are performed using a planar Hall effect bridge sensor at frequencies up to 1 MHz. No external fields...... are needed as the beads are magnetized by the field generated by the applied sensor bias current. We show that the Brownian relaxation frequency can be extracted from fitting the Cole-Cole model to measurements for bead concentrations of 64 mu g/ml or higher and that the measured dynamic magnetic response...... is proportional to the bead concentration. For bead concentrations higher than or equal to 500 mu g/ml, we extract a hydrodynamic diameter of 47(1) nm for the beads, which is close to the nominal bead size of 40 nm. Furthermore, we study the signal vs. bead concentration at a fixed frequency close to the Brownian...

  19. Fluctuations of cytoskeleton-bound microbeads-the effect of bead-receptor binding dynamics

    International Nuclear Information System (INIS)

    Metzner, C; Raupach, C; Mierke, C T; Fabry, B

    2010-01-01

    The cytoskeleton (CSK) of living cells is a crosslinked fiber network, subject to ongoing biochemical remodeling processes that can be visualized by tracking the spontaneous motion of CSK-bound microbeads. The bead motion is characterized by anomalous diffusion with a power-law time evolution of the mean square displacement (MSD), and can be described as a stochastic transport process with apparent diffusivity D and power-law exponent β: MSD ∼ D (t/t 0 ) β . Here we studied whether D and β change with the time that has passed after the initial bead-cell contact, and whether they are sensitive to bead coating (fibronectin, integrin antibodies, poly-L-lysine, albumin) and bead size (0.5-4.5 μm). The measurements are interpreted in the framework of a simple model that describes the bead as an overdamped particle coupled to the fluctuating CSK network by an elastic spring. The viscous damping coefficient characterizes the degree of bead internalization into the cell, and the spring constant characterizes the strength of the binding of the bead to the CSK. The model predicts distinctive signatures of the MSD that change with time as the bead couples more tightly to the CSK and becomes internalized. Experimental data show that the transition from the unbound to the tightly bound state occurs in an all-or-nothing manner. The time point of this transition shows considerable variability between individual cells (2-30 min) and depends on the bead size and bead coating. On average, this transition occurs later for smaller beads and beads coated with ligands that trigger the formation of adhesion complexes (fibronectin, integrin antibodies). Once the bead is linked to the CSK, however, the ligand type and bead size have little effect on the MSD. On longer timescales of several hours after bead addition, smaller beads are internalized into the cell more readily, leading to characteristic changes in the MSD that are consistent with increased viscous damping by the

  20. Ormosil Beads for Insulation of Ground Cryogenic Storage Tanks, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Organically modified silica (Ormosil) aerogel beads developed at Aspen Aerogels, Inc. offer several advantages for retrofitting perlite insulation in NASA's ground...

  1. The bead on a rotating hoop revisited: an unexpected resonance

    Science.gov (United States)

    Raviola, Lisandro A.; Véliz, Maximiliano E.; Salomone, Horacio D.; Olivieri, Néstor A.; Rodríguez, Eduardo E.

    2017-01-01

    The bead on a rotating hoop is a typical problem in mechanics, frequently posed to junior science and engineering students in basic physics courses. Although this system has a rich dynamics, it is usually not analysed beyond the point particle approximation in undergraduate textbooks, nor empirically investigated. Advanced textbooks show the existence of bifurcations owing to the system's nonlinear nature, and some papers demonstrate, from a theoretical standpoint, its points of contact with phase transition phenomena. However, scarce experimental research has been conducted to better understand its behaviour. We show in this paper that a minor modification to the problem leads to appealing consequences that can be studied both theoretically and empirically with the basic conceptual tools and experimental skills available to junior students. In particular, we go beyond the point particle approximation by treating the bead as a rigid spherical body, and explore the effect of a slightly non-vertical hoop's rotation axis that gives rise to a resonant behaviour not considered in previous works. This study can be accomplished by means of digital video and open source software. The experience can motivate an engaging laboratory project by integrating standard curriculum topics, data analysis and experimental exploration.

  2. Porous chitosan beads of superior mechanical properties for the covalent immobilization of enzymes.

    Science.gov (United States)

    Wahba, Marwa I

    2017-12-01

    Porous chitosan beads of superior mechanical properties were produced via a two stepped treatment process. First, the chitosan ionotropic gelation solution was supplemented with Na 2 CO 3 , which acted as a porogen. Afterwards, the beads were chemically cross-linked with glutaraldehyde. This treatment also caused the produced porous chitosan beads to acquire higher observed activities of immobilized β-d-galactosidase (β-gal). The observed activities of the β-gal immobilized onto the 0.2M and the 0.35M Na 2 CO 3 treated beads were 1.63 and 1.91 fold respectively, higher than the activity offered by the control beads. Nevertheless, both the control beads and the 0.2M Na 2 CO 3 beads caused the optimum pH range of β-gal to shift from 4.6-5.1 to ∼2.7-5. The enzyme's optimum temperature shifted from 55 to 60°C after its immobilization onto the control chitosan beads whereas the β-gal immobilized onto the 0.2M Na 2 CO 3 chitosan beads exhibited a temperature optimum of 55-60°C. The reusability study revealed the superiority of the 0.2M Na 2 CO 3 treated beads which retained 59.1% of their initial activity during the 13th enzymatic cycle. On the other hand, the control chitosan beads were fragmented and lost their activity after only four enzymatic cycles. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Chinese and Venetian glass beads excavated from Fais Island in Micronesia

    International Nuclear Information System (INIS)

    Intoh, Michiko

    1997-01-01

    Full text: Over 830 glass beads were excavated from a late prehistoric cemetery site on Fais Island in the Caroline Islands, Micronesia In one of the 13 excavated burials a young woman had more that 310 glass beads around her wrist. Bone collagen from this burial was dated by AMS to 387 + 64 BP. The associated glass beads were classified into three groups based on colour and size. A sample from each group was examined for evidence of manufacturing technique. The chemical composition was determined using an X-ray microanalyser. The first group consisted of more than 300 pale green, transparent glass beads which are less than 2 mm in diameter. The chemical composition is high in PbO (75.22%) while low in MgO. Such a high lead content is characteristic of Chinese glass. The manufacturing technique could not be determined because the surfaces were too eroded. The second group contains several yellow, translucent glass beads. The chemical composition is also high in PbO (54.8%) and low in MgO. The beads were made by winding. The combination of winding and high lead strongly indicates that the beads were made in China. The third group had only one white, translucent glass bead. It has particular white stripes which suggest that it is a 'gooseberry' bead which was made in Venice between the sixteenth and eighteenth centuries. In conclusion, both Chinese and Venetian glass beads co-existed on Fais Island around the time of European contact. They are likely to have been brought in from an area which had access to both beads. Island South-East Asia is tentatively considered to be the source area

  4. Two kinds of ketoprofen enteric gel beads (CA and CS-SA using biopolymer alginate

    Directory of Open Access Journals (Sweden)

    Bingchao Cheng

    2018-03-01

    Full Text Available To obtain expected rapid-release and sustained-release of ketoprofen gel beads, this paper adopted biopolymer alginate to prepare alginate beads and chitosan-alginate gel beads. Formulation factors were investigated and optimized by the single factor test. The release of ketoprofen from calcium alginate gel beads in pH 1.0 hydrochloric acid solution was less than 10% during 2 h, then in pH6.8 was about 95% during 45 min, which met the requirements of rapid-release preparations. However, the drug release of chitosan-alginate gel beads in pH1.0 was less than 5% during 2 h, then in pH6.8 was about 50% during 6 h and reached more than 95% during 12 h, which had a good sustained-release behavior. In addition, the release kinetics of keteprofen from the calcium alginate gel beads fitted well with the Korsmeyer–Peppas model and followed a case-II transport mechanism. However, the release of keteprofen from the chitosan-alginate gel beads exhibited a non-Fickian mechanism and based on the mixed mechanisms of diffusion and polymer relaxation from chitosan-alginate beads. In a word, alginate gel beads of ketoprofen were instant analgesic, while chitosan-alginate gel beads could control the release of ketoprofen during gastro-intestinal tract and prolong the drug's action time. Keywords: Gel beads, Enteric rapid-release, Enteric sustained-release, Ketoprofen

  5. Viscosity of dilute suspensions of rigid bead arrays at low shear: accounting for the variation in hydrodynamic stress over the bead surfaces.

    Science.gov (United States)

    Allison, Stuart A; Pei, Hongxia

    2009-06-11

    In this work, we examine the viscosity of a dilute suspension of irregularly shaped particles at low shear. A particle is modeled as a rigid array of nonoverlapping beads of variable size and geometry. Starting from a boundary element formalism, approximate account is taken of the variation in hydrodynamic stress over the surface of the individual beads. For a touching dimer of two identical beads, the predicted viscosity is lower than the exact value by 5.2%. The methodology is then applied to several other model systems including tetramers of variable conformation and linear strings of touching beads. An analysis is also carried out of the viscosity and translational diffusion of several dilute amino acids and diglycine in water. It is concluded that continuum hydrodynamic modeling with stick boundary conditions is unable to account for the experimental viscosity and diffusion data simultaneously. A model intermediate between "stick" and "slip" could possibly reconcile theory and experiment.

  6. Electronic phase separation in insulating (Ga, Mn) As with low compensation: super-paramagnetism and hopping conduction

    Science.gov (United States)

    Yuan, Ye; Wang, Mao; Xu, Chi; Hübner, René; Böttger, Roman; Jakiela, Rafal; Helm, Manfred; Sawicki, Maciej; Zhou, Shengqiang

    2018-03-01

    In the present work, low compensated insulating (Ga,Mn)As with 0.7% Mn is obtained by ion implantation combined with pulsed laser melting. The sample shows variable-range hopping transport behavior with a Coulomb gap in the vicinity of the Fermi energy, and the activation energy is reduced by an external magnetic field. A blocking super-paramagnetism is observed rather than ferromagnetism. Below the blocking temperature, the sample exhibits a colossal negative magnetoresistance. Our studies confirm that the disorder-induced electronic phase separation occurs in (Ga,Mn)As samples with a Mn concentration in the insulator-metal transition regime, and it can account for the observed superparamagnetism and the colossal magnetoresistance.

  7. Use of magnetic beads for Gram staining of bacteria in aqueous suspension.

    Science.gov (United States)

    Yazdankhah, S P; Sørum, H; Larsen, H J; Gogstad, G

    2001-12-01

    A Gram staining technique was developed using monodisperse magnetic beads in concentrating bacteria in suspension for downstream application. The technique does not require heat fixation of organisms, electrical power, or a microscope. Gram-negative and Gram-positive bacteria were identified macroscopically based on the colour of the suspension. The bacteria concentrated on magnetic beads may also be identified microscopically.

  8. Chemical–physical characterisation of Early Iron Age glass beads from Central Europe

    Energy Technology Data Exchange (ETDEWEB)

    Agua, F.; Conde, J.F.; Kobylińska, U.; Kobyliński, Z.; García-Heras, M.; Villegas, M.A.

    2017-07-01

    Archaeological excavation of the Institute of Archaeology and Ethnology (Polish Academy of Sciences, PAN) at several Iron Age sites located in West Poland and South Germany has allowed the recovery of an important set of coloured glass beads mostly decorated (6th–4th centuries BC). The present paper summarises the results obtained through the chemical and microstructural characterisation of such beads. The research was carried out by binocular microscope observations, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry and visible spectrophotometry. The main objective was to attain information on the production technology and conservation state of these beads. The results indicated that all them were produced with soda lime silicate glass, even though two groups can be separated: (i) beads containing high MgO percentages made from plant ashes as an alkaline source, and (ii) beads containing low MgO percentages made from natron as an alkaline source. As regards decorations, opaque white was obtained from tin oxide, turquoise blue from Cu2+-ions, and opaque yellow from lead antimonate. Additionally, results showed microstructural and microcrystalline differences between some glass beads studied here and other glass beads from Mediterranean areas, dated in the same chronological period. This fact pointed out the valuable role given to these beads by Iron Age communities from Central Europe. (Author)

  9. OBT analysis method using polyethylene beads for limited quantities of animal tissue

    International Nuclear Information System (INIS)

    Kim, S.B.; Stuart, M.

    2015-01-01

    This study presents a polyethylene beads method for OBT determination in animal tissues and animal products for cases where the amount of water recovered by combustion is limited by sample size or quantity. In the method, the amount of water recovered after combustion is enhanced by adding tritium-free polyethylene beads to the sample prior to combustion in an oxygen bomb. The method reduces process time by allowing the combustion water to be easily collected with a pipette. Sufficient water recovery was achieved using the polyethylene beads method when 2 g of dry animal tissue or animal product were combusted with 2 g of polyethylene beads. Correction factors, which account for the dilution due to the combustion water of the beads, are provided for beef, chicken, pork, fish and clams, as well as egg, milk and cheese. The method was tested by comparing its OBT results with those of the conventional method using animal samples collected on the Chalk River Laboratories (CRL) site. The results determined that the polyethylene beads method added no more than 25% uncertainty when appropriate correction factors are used. - Highlights: • Polyethylene beads method for OBT determination in animal tissues and animal products were determined. • The method reduces process time. • The polyethylene beads method added no more than 25% uncertainty when appropriate correction factors are used

  10. Magnetic nanoparticle-loaded alginate beads for local micro-actuation of in vitro tissue constructs.

    Science.gov (United States)

    Alshehri, Awatef M; Wilson, Otto C; Dahal, Bishnu; Philip, John; Luo, Xiaolong; Raub, Christopher B

    2017-11-01

    Magnetic nanoparticles (MNPs) self-align and transduce magnetic force, two properties which lead to promising applications in cell and tissue engineering. However, the toxicity of MNPs to cells which uptake them is a major impediment to applications in engineered tissue constructs. To address this problem, MNPs were embedded in millimeter-scale alginate beads, coated with glutaraldehyde cross-linked chitosan, and loaded in acellular and MDA-MB-231 cancer cell-seeded collagen hydrogels, providing local micro-actuation under an external magnetic field. Brightfield microscopy was used to assess nanoparticle diffusion from the bead. Phase contrast microscopy and digital image correlation were used to track collagen matrix displacement and estimate intratissue strain under magnetic actuation. Coating the magnetic alginate beads with glutaraldehyde-chitosan prevents bulk diffusion of nanoparticles into the surrounding microenvironment. Further, the beads exert force on the surrounding collagen gel and cells, resulting in intratissue strains of 0-10% tunable with bead dimensions, collagen density, and distance from the bead. Cells seeded adjacent to the embedded beads are subjected to strain gradients without loss of cell viability over two days culture. This study describes a simple way to fabricate crosslinked magnetic alginate beads to load in a collagen tissue construct without direct exposure of the construct to nanoparticles. The findings are significant to in vitro studies of mechanobiology in enabling precise control over dynamic mechanical loading of tissue constructs. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Sustained multiple organ ischaemia after transarterial chemoembolization with drug-eluting beads for hepatocellular carcinoma.

    Science.gov (United States)

    Kim, Young Woon; Kwon, Jung Hyun; Nam, Soon Woo; Jang, Jeong Won; Jung, Hyun Suk; Shin, Yu Ri; Park, Eun Su; Shim, Dong Jae

    2018-02-01

    Transarterial chemoembolization (TACE) with drug-eluting beads (DC beads) may enhance drug delivery to tumours and reduce systemic toxicity. TACE with DC beads leads to significantly fewer serious side-effects compared with conventional TACE. A 66-year-old man with hepatocellular carcinoma (HCC) complained of continuous abdominal pain 1 month after TACE with DC beads. At the time of TACE, angiography revealed severe stenosis of both hepatic arteries. The diagnostic work up on admission suggested severe bile duct injury with regional bile duct dilatation, segmental liver and spleen infarction, necrotizing pancreatitis, as well as gastric and duodenal ulcers. The pathology specimens of the duodenum contained DC beads that had passed through small vessels in the connective tissue. The patient's condition appeared to improve after 2 weeks of antibiotic treatment and supportive care, but new multifocal liver and spleen infarction subsequently developed. After 2 months, he was well enough to be discharged. His HCC partially responded to the TACE with DC beads but eventually progressed and he died after 11 months. The present case report highlights unexpected ongoing multiple organ ischaemia in a 66-year-old man treated for HCC using TACE with DC beads. The use of TACE with DC beads should be carefully considered in patients with vascular strictures or aberrant blood supply.

  12. EXPERIMENTAL TESTING OF DRAW-BEAD RESTRAINING FORCE IN SHEET METAL FORMING

    Institute of Scientific and Technical Information of China (English)

    J.H. Yang; J. Chen; D.N. He; X. Y. Ruan

    2003-01-01

    Due to complexities of draw-bead restraining force calculated according to theory anddepending on sheet metal forming properties experiment testing system, a simplifiedmethod to calculate draw-bead restraining force is put forward by experimental methodin cup-shaped drawing process. The experimental results were compared with numer-ical results and proved agreement. It shows the method is effective.

  13. Evaluation of the Seismic Characterision of Select Engineered Nanoparticles in Saturated Glass Beads

    Science.gov (United States)

    A laboratory testing apparatus was developed for the study of seismic body wave propagation through nanoparticles dispersed in pore fluid that is essentially saturating glass beads. First, the responses of water-saturated glass bead specimens were studied to establish baseline si...

  14. Preparation of chitosan/amino multiwalled carbon nanotubes nanocomposite beads for bilirubin adsorption in hemoperfusion.

    Science.gov (United States)

    Zong, Wenhui; Chen, Jian; Han, Wenyan; Chen, Jie; Wang, Yue; Wang, Weichao; Cheng, Guanghui; Ou, Lailiang; Yu, Yaoting

    2018-01-01

    Chitosan-carbon nanotube composite beads combines the advantages of chitosan in forming a stable biocompatible framework and carbon nanotube that provide nanometer effects (high strength and high specific surface area etc.). In this study, chitosan/amino multiwalled carbon nanotubes (CS/AMWCNT) composite beads was prepared by phase-inversion method, in which CS and AMWCNT was crosslinked by ethylene glycol diglycidyl ether (EGDE). The CS/AMWCNT nanocomposite beads produced has been characterized by BET, SEM, TGA, and Raman spectroscopy which exhibited enhanced thermal stability due to the incorporation of AMWCNT. Mechanical test results showed that mechanical strength of the CS/AMWCNT composite beads was significantly enhanced when comparing to unmodified chitosan beads, the breakage percentage decreased from 34.1% to 0.67%. The adsorption capacity for bilirubin was measured in PBS and BSA solutions, and the CS/AMWCNT composite beads with 5 wt% AMWCNT showed much higher adsorption capacity (12.7 mg/g in PBS and 7.6 mg/g in BSA) to bilirubin than chitosan beads (8.5 mg/g in PBS and 4.2 mg/g in BSA). Our nanocomposite beads with excellent hemocompatibility has a high potential application in blood purification as an efficient adsorbent for bilirubin. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 96-103, 2018. © 2016 Wiley Periodicals, Inc.

  15. Tunable bead-on-string microstructures fabricated by mechano-electrospinning

    International Nuclear Information System (INIS)

    Bu Ningbin; Huang Yongan; Deng Huixu; Yin Zhouping

    2012-01-01

    In this paper, bead-on-string microstructures are fabricated by the mechano-electrospinning (MES) process in a continuously tunable manner. The thin jet is pulled onto the substrate by the stable electric field force and tunable mechanical drawing force, and then the bead-on-string structures are generated by means of the force exerted on the jet, which changes from capillary force and resisting viscosity force to friction force at the contact point in the horizontal direction. In a stable bead-on-string formation process, one cycle can be divided into three stages from the point of view of the jet behaviour: being anchored, being stretched, and skipping. The bead size and the bead gap are continuously tunable through the MES process. The fabrication mechanisms of the bead-on-string microstructure are uncovered through theoretical analysis and experimental characterization. When a critical velocity is achieved, the jet directly falls on the substrate without accumulation since the mechanical drawing force in the horizontal direction overtakes the capillary force, which leads the bead-on-string microstructures to a continuous fibre line. It is a flexible and highly controllable method to fabricate bead-on-string microstructures.

  16. Concanavalin A immobilized magnetic poly(glycidyl methacrylate) beads for prostate specific antigen binding.

    Science.gov (United States)

    Idil, Neslihan; Perçin, Işık; Karakoç, Veyis; Yavuz, Handan; Aksöz, Nilüfer; Denizli, Adil

    2015-10-01

    The aim of this study was to prepare Concanavalin A (Con A) immobilized magnetic poly(glycidyl methacrylate) (mPGMA) beads for prostate specific antigen (PSA) binding and to study binding capacities of the beads using lectin-glycoprotein interactions. Firstly, iron oxide nanoparticles were synthesized by co-precipitation method and then, beads were synthesized by dispersion polymerization in the presence of iron oxide nanoparticles. Con A molecules were both covalently immobilized onto the beads directly and through the spacer arm (1,6-diaminohexane-HDMA). The total PSA and free PSA binding onto the mPGMA-HDMA-Con A beads were higher than that of the mPGMA-Con A beads. Maximum PSA binding capacity was observed as 91.2 ng/g. Approximately 45% of the bound PSA was eluted by using 0.1 M mannose as elution agent. The mPGMA-HDMA-Con A beads could be reused without a remarkable decrease in the binding capacities after 5 binding-desorption cycles. Serum fractions were analyzed using SDS-PAGE. The mPGMA-HDMA-Con A beads could be useful for the detection of PSA and suggested as a model system for other glycoprotein biomarkers. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. In vivo cleansing efficacy of biodegradable exfoliating beads assessed by skin bioengineering techniques.

    Science.gov (United States)

    Kitsongsermthon, J; Duangweang, K; Kreepoke, J; Tansirikongkol, A

    2017-11-01

    The plastic microbeads, used in many cleansers, will be banned in cosmetic and personal care products within 2017 since they are non-degradable and can disturb the living organisms in water reservoirs. Various choices of biodegradable beads are commercially available, but their efficacy has not been proven yet. This study aimed to compare the cleansing efficacy in dirt and sebum removal aspects of three types of exfoliating beads. The gel scrubs with polyethylene (PE) beads, mannan beads or wax beads, were formulated and evaluated for their stability. The in vivo evaluation was done in 38 healthy volunteers and the skin irritation, efficacy for dirt and sebum removal were measured by Mexameter ® , Colorimeter ® , and Sebumeter ® , respectively. The selected gel scrubs did not cause an irritation in any volunteers. The differences in dirt residues between before and after scrubbing were not statistically significant among three gel scrubs and the similar result was also reported in the sebum removal study. All gel scrubs demonstrated the comparable cleansing efficacy in term of dirt and sebum removal. Thus, mannan beads and wax beads may be replaced non-biodegradable PE beads to achieve the similar cleansing effect. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  18. Capture of DNA in microfluidic channel using magnetic beads: increasing capture efficiency with integrated microfluidic mixer

    DEFF Research Database (Denmark)

    Lund-Olesen, Torsten; Dufva, Hans Martin; Hansen, Mikkel Fougt

    2007-01-01

    We have studied the hybridization of target DNA in solution with probe DNA on magnetic beads immobilized on the channel sidewalls in a magnetic bead separator. The hybridization is carried out under a liquid flow and is diffusion limited. Two systems are compared: one with a straight microfluidic...... place on the surface in a microfluidic system....

  19. Intraarticular application of superparamagnetic nanoparticles and their uptake by synovial membrane-an experimental study in sheep

    Energy Technology Data Exchange (ETDEWEB)

    Schulze, Katja [Musculoskeletal Research Unit, Equine Hospital, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich (Switzerland); Koch, Annette [Department of Chemistry and Applied BioSciences, Swiss Federal Institute of Technology Zurich (ETH Zurich), Winterthurerstrasse 190, 8057 Zurich (Switzerland); Schoepf, Bernhard [Musculoskeletal Research Unit, Equine Hospital, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich (Switzerland); Petri, Alke [Laboratory of Powder Technology, Swiss Federal Institute of Technology (EPFL), Lausanne (Switzerland); Steitz, Benedikt [Laboratory of Powder Technology, Swiss Federal Institute of Technology (EPFL), Lausanne (Switzerland); Chastellain, Mathieu [Laboratory of Powder Technology, Swiss Federal Institute of Technology (EPFL), Lausanne (Switzerland); Hofmann, Margarethe [MatSearch, Chemin Jean Pavillard 14, 1009 Pully (Switzerland); Hofmann, Heinrich [Laboratory of Powder Technology, Swiss Federal Institute of Technology (EPFL), Lausanne (Switzerland); Rechenberg, Brigitte von [Musculoskeletal Research Unit, Equine Hospital, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich (Switzerland)]. E-mail: bvonrechenberg@vetclinics.unizh.ch

    2005-05-15

    A superparamagnetic iron oxide nanoparticle, coated with polyvinyl alcohol (PVA-SPION) and its fluorescently functionalized analogue (amino-PVA-Cy3.5-SPION) were compared in vivo as proof of principle for future use in magnetic drug targeting in inflammatory joint diseases. They were injected either intraarticularly or periarticularly and their uptake by cells of the synovial membrane was evaluated. Uptake was completed in 48 h and was enforced by an extracorporally applied magnet.

  20. Self-assembly of a superparamagnetic raspberry-like silica/iron oxide nanocomposite using epoxy-amine coupling chemistry.

    Science.gov (United States)

    Cano, Manuel; de la Cueva-Méndez, Guillermo

    2015-02-28

    The fabrication of colloidal nanocomposites would benefit from controlled hetero-assembly of ready-made particles through covalent bonding. Here we used epoxy-amine coupling chemistry to promote the self-assembly of superparamagnetic raspberry-like nanocomposites. This adaptable method induced the covalent attachment of iron oxide nanoparticles sparsely coated with amine groups onto epoxylated silica cores in the absence of other reactants.

  1. Intraarticular application of superparamagnetic nanoparticles and their uptake by synovial membrane-an experimental study in sheep

    International Nuclear Information System (INIS)

    Schulze, Katja; Koch, Annette; Schoepf, Bernhard; Petri, Alke; Steitz, Benedikt; Chastellain, Mathieu; Hofmann, Margarethe; Hofmann, Heinrich; Rechenberg, Brigitte von

    2005-01-01

    A superparamagnetic iron oxide nanoparticle, coated with polyvinyl alcohol (PVA-SPION) and its fluorescently functionalized analogue (amino-PVA-Cy3.5-SPION) were compared in vivo as proof of principle for future use in magnetic drug targeting in inflammatory joint diseases. They were injected either intraarticularly or periarticularly and their uptake by cells of the synovial membrane was evaluated. Uptake was completed in 48 h and was enforced by an extracorporally applied magnet

  2. Polymerized serum albumin beads for use as slow-release adjuvants

    International Nuclear Information System (INIS)

    Martin, M.E.D.

    1987-02-01

    Experimental vaccines have been made by covalently bonding virus particles into polymerized rabbit serum albumin beads. Using Nodamura virus as a model antigen, these model vaccines induced specific humoral antibody production, comparable with that achieved using Freund's adjuvants. Virus specific antibodies were also induced when Nodamura virus was covalently attached to the bead surface using different crosslinkers. However, when poliovirus type 2 (Sabin strain) was polymerized into beads, the levels of neutralizing antibodies were insignificant compared with control aqueous vaccines. The synthetic immunostimulator, muramyl dipeptide, was included with bead vaccines in an attempt to potentiate the immune response. Immunostimulation is achieved by a slow release of antigen coinciding with the gradual breakdown of bead structure. Methods used include radio-iodination and radioimmunoassay. 65 figs., 6 tabs., 173 refs

  3. Preparation and Characterization of Highly Spherical Silica-titania Aerogel Beads with High Surface Area

    Directory of Open Access Journals (Sweden)

    YU Yu-xi

    2017-02-01

    Full Text Available The silica-titania aerogel beads were synthesized through sol-gel reaction followed by supercritical drying, in which TEOS and TBT as co-precursors, EtOH as solvents, HAC and NH3·H2O as catalysts. The as-prepared aerogel beads were characterized by SEM,TEM,XRD,FT-IR,TG-DTA and nitrogen adsorption-desorption. The results indicate that the diameter distribution of beads are between 1-8mm, the average diameter of beads is 3.5mm. The aerogel beads have nanoporous network structure with high specific surface area of 914.5m2/g, and the TiO2 particles are distributed in the aerogel uniformly, which keep the anatase crystal under high temperature.

  4. Investigation on rare earth magnets recycling by organophosphoric extractant encapsulated polymeric beads for separation of dysprosium

    International Nuclear Information System (INIS)

    Yadav, Kartikey K.; Singh, D.K.; Kain, V.

    2017-01-01

    Rare earth elements (REEs) are a basic requirement of the electronics and new industries including green technology. In the present work an organophosphoric extractant encapsulating polyethersulfone (PES) beads has been developed and employed for dysprosium (Dy) separation from aqueous stream. Polyethersulfonic beads encapsulating PC88A were prepared by phase inversion method. During the synthesis of the beads, preparatory parameters were also optimized to obtain best suited beads which were subsequently characterized for their encapsulation capacity and micro structural investigation. The results obtained in the present investigation suggested that PES/PVAJPC88A composite beads could be used for separation of rare earths from aqueous medium obtained from the solubilisation of magnetic scrap materials

  5. Predicting of bead undercut defects in high-speed gas metal arc welding (GMAW)

    Institute of Scientific and Technical Information of China (English)

    Wen-jing XU; Chuan-song WU; De-gang ZOU

    2008-01-01

    In the gas metal arc welding (GMAW) process, when the welding speed reaches a certain threshold, there will be an onset of weld bead undercut defects which limit the further increase of the welding speed. Establishing a mathematical model for high-speed GMAW to predict the tendency of bead undercuts is of great significance to pre-vent such defects. Under the action of various forces, the transferred metal from filler wire to the weld pool, and the geometry and dimension of the pool itself decide if the bead undercut occurs or not. The previous model simpli-fied the pool shape too much. In this paper, based on the actual weld pool geometry and dimension calculated from a numerical model, a hydrostatic model for liquid metal surface is used to study the onset of bead undercut defects in the high-speed welding process and the effects of dif-ferent welding parameters on the bead undercut tendency.

  6. Speciation-dependent studies on removal of arsenic by iron-doped calcium alginate beads

    International Nuclear Information System (INIS)

    Banerjee, Anupam; Nayak, Dalia; Lahiri, Susanta

    2007-01-01

    This work aims to study the differential attitude of Fe-doped calcium alginate (Fe-CA) beads towards As(III) and As(V) compounds so that speciation-dependent environmentally sustainable methodologies can be developed for removal of arsenic from contaminated water. Throughout the experiment, 76 As has been used as precursor of stable arsenic. The affinity of As(V) towards the Fe-CA beads is greater than that of As(III). Removal efficiency of Fe-CA beads for As(V) increases with increasing number of beads and longer shaking times. At pH 3, 30 Fe-CA beads remove As(V) completely from a solution containing 20 mg kg -1 As(V). The technique has been successfully applied to the ground water collected from an arsenic-contaminated area

  7. Hierarchically templated beads with tailored pore structure for phosphopeptide capture and phosphoproteomics

    DEFF Research Database (Denmark)

    Wierzbicka, Celina; Torsetnes, Silje B.; Jensen, Ole N.

    2017-01-01

    Two templating approaches to produce imprinted phosphotyrosine capture beads with a controllable pore structure are reported and compared with respect to their ability to enrich phosphopeptides from a tryptic peptide mixture. The beads were prepared by the polymerization of urea-based host monomers...... and crosslinkers inside the pores of macroporous silica beads with both free and immobilized template. In the final step the silica was removed by fluoride etching resulting in mesoporous polymer replicas with narrow pore size distributions, pore diameters ≈ 10 nm and surface area > 260 m2 g-1. The beads displayed...... pronounced phosphotyrosine affinity and selectivity in binding tests using model peptides in acetonitrile rich solutions with a performance surpassing solution polymerized bulk imprinted materials. Tests of the beads for the enrichment of phosphopeptides from tryptic digests of twelve proteins revealed both...

  8. Formulation of Synthesized Zinc Oxide Nanopowder into Hybrid Beads for Dye Separation

    Directory of Open Access Journals (Sweden)

    H. Shokry Hassan

    2014-01-01

    Full Text Available The sol-gel prepared zinc oxide nanopowder was immobilized onto alginate-polyvinyl alcohol polymer blend to fabricate novel biocomposite beads. Various physicochemical characterization techniques have been utilized to identify the crystalline, morphological, and chemical structures of both the fabricated zinc oxide hybrid beads and their corresponding zinc oxide nanopowder. The thermal stability investigations demonstrate that ZnO nanopowder stability dramatically decreased with its immobilization into the polymeric alginate and PVA matrix. The formulated beads had very strong mechanical strength and they are difficult to be broken up to 1500 rpm. Moreover, these hybrid beads are chemically stable at the acidic media (pH < 7 especially within the pH range of 2–7. Finally, the applicability of the formulated ZnO hybrid beads for C.I. basic blue 41 (BB41 decolorization from aqueous solution was examined.

  9. The Role of an Aggrecan 32mer Fragment in Post-Traumatic Osteoarthritis

    Science.gov (United States)

    2017-10-01

    streptavidin-coated AlphaLISA donor beads and incubate for 30 minutes.  Read sample absorbance at 615nm on the PerkinElmer Enspire plate reader. 11...HRPO approval within the next six months. Nothing to report 15 Significant changes in use or care of human subjects, vertebrate animals ...human subjects, vertebrate animals , biohazards, and/or select agents during the reporting period. If required, were these changes approved by the

  10. Subtle cytotoxicity and genotoxicity differences in superparamagnetic iron oxide nanoparticles coated with various functional groups

    Directory of Open Access Journals (Sweden)

    Hong SC

    2011-12-01

    Full Text Available Seong Cheol Hong1,*, Jong Ho Lee1,*, Jaewook Lee1, Hyeon Yong Kim1, Jung Youn Park2, Johann Cho3, Jaebeom Lee1, Dong-Wook Han11Department of Nanomedical Engineering, BK21 Nano Fusion Technology Division, College of Nanoscience and Nanotechnology, Pusan National University, 2Department of Biotechnology Research, National Fisheries Research and Development Institute, Busan, 3Electronic Materials Lab, Samsung Corning Precision Materials Co, Ltd, Gumi City, Gyeongsangbukdo, Korea*These authors contributed equally to this workAbstract: Superparamagnetic iron oxide nanoparticles (SPIONs have been widely utilized for the diagnosis and therapy of specific diseases, as magnetic resonance imaging (MRI contrast agents and drug-delivery carriers, due to their easy transportation to targeted areas by an external magnetic field. For such biomedical applications, SPIONs must have multifunctional characteristics, including optimized size and modified surface. However, the biofunctionality and biocompatibility of SPIONs with various surface functional groups of different sizes have yet to be elucidated clearly. Therefore, it is important to carefully monitor the cytotoxicity and genotoxicity of SPIONs that are surfaced-modified with various functional groups of different sizes. In this study, we evaluated SPIONs with diameters of approximately 10 nm and 100~150 nm, containing different surface functional groups. SPIONs were covered with –O-groups, so-called bare SPIONs. Following this, they were modified with three different functional groups – hydroxyl (–OH, carboxylic (–COOH, and amine (–NH2 groups – by coating their surfaces with tetraethyl orthosilicate (TEOS, (3-aminopropyltrimethoxysilane (APTMS, TEOS-APTMS, or citrate, which imparted different surface charges and sizes to the particles. The effects of SPIONs coated with these functional groups on mitochondrial activity, intracellular accumulation of reactive oxygen species, membrane integrity

  11. Oxidative stress response in neural stem cells exposed to different superparamagnetic iron oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Pongrac IM

    2016-04-01

    Full Text Available Igor M Pongrac,1 Ivan Pavičić,2 Mirta Milić,2 Lada Brkič Ahmed,1 Michal Babič,3 Daniel Horák,3 Ivana Vinković Vrček,2 Srećko Gajović1 1School of Medicine, Croatian Institute for Brain Research, University of Zagreb, 2Institute for Medical Research and Occupational Health, Zagreb, Croatia; 3Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic Abstract: Biocompatibility, safety, and risk assessments of superparamagnetic iron oxide nanoparticles (SPIONs are of the highest priority in researching their application in biomedicine. One improvement in the biological properties of SPIONs may be achieved by different functionalization and surface modifications. This study aims to investigate how a different surface functionalization of SPIONs – uncoated, coated with D-mannose, or coated with poly-L-lysine – affects biocompatibility. We sought to investigate murine neural stem cells (NSCs as important model system for regenerative medicine. To reveal the possible mechanism of toxicity of SPIONs on NSCs, levels of reactive oxygen species, intracellular glutathione, mitochondrial membrane potential, cell-membrane potential, DNA damage, and activities of SOD and GPx were examined. Even in cases where reactive oxygen species levels were significantly lowered in NSCs exposed to SPIONs, we found depleted intracellular glutathione levels, altered activities of SOD and GPx, hyperpolarization of the mitochondrial membrane, dissipated cell-membrane potential, and increased DNA damage, irrespective of the surface coating applied for SPION stabilization. Although surface coating should prevent the toxic effects of SPIONs, our results showed that all of the tested SPION types affected the NSCs similarly, indicating that mitochondrial homeostasis is their major cellular target. Despite the claimed biomedical benefits of SPIONs, the refined determination of their effects on various cellular functions

  12. Superparamagnetic poly(methyl methacrylate) nanoparticles surface modified with folic acid presenting cell uptake mediated by endocytosis

    Energy Technology Data Exchange (ETDEWEB)

    Feuser, Paulo Emilio [Federal University of Santa Catarina, Department of Chemical Engineering and Food Engineering (Brazil); Jacques, Amanda Virtuoso [Federal University of Santa Catarina, Department of Clinical Analyses (Brazil); Arévalo, Juan Marcelo Carpio; Rocha, Maria Eliane Merlin [Federal University of Paraná, Department of Biochemistry and Molecular Biology (Brazil); Santos-Silva, Maria Claudia dos [Federal University of Santa Catarina, Department of Clinical Analyses (Brazil); Sayer, Claudia; Araújo, Pedro H. Hermes de, E-mail: pedro.h.araujo@ufsc.br [Federal University of Santa Catarina, Department of Chemical Engineering and Food Engineering (Brazil)

    2016-04-15

    The encapsulation of superparamagnetic nanoparticles (MNPs) in polymeric nanoparticles (NPs) with modified surfaces can improve targeted delivery and induce cell death by hyperthermia. The goals of this study were to synthesize and characterize surface modified superparamagnetic poly(methyl methacrylate) with folic acid (FA) prepared by miniemulsion polymerization (MNPsPMMA-FA) and to evaluate their in vitro cytotoxicity and cellular uptake in non-tumor cells, murine fibroblast (L929) cells and tumor cells that overexpressed folate receptor (FR) β, and chronic myeloid leukemia cells in blast crisis (K562). Lastly, hemolysis assays were performed on human red blood cells. MNPsPMMA-FA presented an average mean diameter of 135 nm and a saturation magnetization (Ms) value of 37 emu/g of iron oxide, as well as superparamagnetic behavior. The MNPsPMMA-FA did not present cytotoxicity in L929 and K562 cells. Cellular uptake assays showed a higher uptake of MNPsPMMA-FA than MNPsPMMA in K562 cells when incubated at 37 °C. On the other hand, MNPsPMMA-FA showed a low uptake when endocytosis mechanisms were blocked at low temperature (4 °C), suggesting that the MNPsPMMA-FA uptake was mediated by endocytosis. High concentrations of MNPsPMMA-FA showed hemocompatibility when incubated for 24 h in human red blood cells. Therefore, our results suggest that these carrier systems can be an excellent alternative in targeted drug delivery via FR.

  13. Superparamagnetic poly(methyl methacrylate) nanoparticles surface modified with folic acid presenting cell uptake mediated by endocytosis

    International Nuclear Information System (INIS)

    Feuser, Paulo Emilio; Jacques, Amanda Virtuoso; Arévalo, Juan Marcelo Carpio; Rocha, Maria Eliane Merlin; Santos-Silva, Maria Claudia dos; Sayer, Claudia; Araújo, Pedro H. Hermes de

    2016-01-01

    The encapsulation of superparamagnetic nanoparticles (MNPs) in polymeric nanoparticles (NPs) with modified surfaces can improve targeted delivery and induce cell death by hyperthermia. The goals of this study were to synthesize and characterize surface modified superparamagnetic poly(methyl methacrylate) with folic acid (FA) prepared by miniemulsion polymerization (MNPsPMMA-FA) and to evaluate their in vitro cytotoxicity and cellular uptake in non-tumor cells, murine fibroblast (L929) cells and tumor cells that overexpressed folate receptor (FR) β, and chronic myeloid leukemia cells in blast crisis (K562). Lastly, hemolysis assays were performed on human red blood cells. MNPsPMMA-FA presented an average mean diameter of 135 nm and a saturation magnetization (Ms) value of 37 emu/g of iron oxide, as well as superparamagnetic behavior. The MNPsPMMA-FA did not present cytotoxicity in L929 and K562 cells. Cellular uptake assays showed a higher uptake of MNPsPMMA-FA than MNPsPMMA in K562 cells when incubated at 37 °C. On the other hand, MNPsPMMA-FA showed a low uptake when endocytosis mechanisms were blocked at low temperature (4 °C), suggesting that the MNPsPMMA-FA uptake was mediated by endocytosis. High concentrations of MNPsPMMA-FA showed hemocompatibility when incubated for 24 h in human red blood cells. Therefore, our results suggest that these carrier systems can be an excellent alternative in targeted drug delivery via FR.

  14. Superparamagnetic poly(methyl methacrylate) nanoparticles surface modified with folic acid presenting cell uptake mediated by endocytosis

    Science.gov (United States)

    Feuser, Paulo Emilio; Jacques, Amanda Virtuoso; Arévalo, Juan Marcelo Carpio; Rocha, Maria Eliane Merlin; dos Santos-Silva, Maria Claudia; Sayer, Claudia; de Araújo, Pedro H. Hermes

    2016-04-01

    The encapsulation of superparamagnetic nanoparticles (MNPs) in polymeric nanoparticles (NPs) with modified surfaces can improve targeted delivery and induce cell death by hyperthermia. The goals of this study were to synthesize and characterize surface modified superparamagnetic poly(methyl methacrylate) with folic acid (FA) prepared by miniemulsion polymerization (MNPsPMMA-FA) and to evaluate their in vitro cytotoxicity and cellular uptake in non-tumor cells, murine fibroblast (L929) cells and tumor cells that overexpressed folate receptor (FR) β, and chronic myeloid leukemia cells in blast crisis (K562). Lastly, hemolysis assays were performed on human red blood cells. MNPsPMMA-FA presented an average mean diameter of 135 nm and a saturation magnetization (Ms) value of 37 emu/g of iron oxide, as well as superparamagnetic behavior. The MNPsPMMA-FA did not present cytotoxicity in L929 and K562 cells. Cellular uptake assays showed a higher uptake of MNPsPMMA-FA than MNPsPMMA in K562 cells when incubated at 37 °C. On the other hand, MNPsPMMA-FA showed a low uptake when endocytosis mechanisms were blocked at low temperature (4 °C), suggesting that the MNPsPMMA-FA uptake was mediated by endocytosis. High concentrations of MNPsPMMA-FA showed hemocompatibility when incubated for 24 h in human red blood cells. Therefore, our results suggest that these carrier systems can be an excellent alternative in targeted drug delivery via FR.

  15. Ultrasmall cationic superparamagnetic iron oxide nanoparticles as nontoxic and efficient MRI contrast agent and magnetic-targeting tool

    Science.gov (United States)

    Uchiyama, Mayara Klimuk; Toma, Sergio Hiroshi; Rodrigues, Stephen Fernandes; Shimada, Ana Lucia Borges; Loiola, Rodrigo Azevedo; Cervantes Rodríguez, Hernán Joel; Oliveira, Pedro Vitoriano; Luz, Maciel Santos; Rabbani, Said Rahnamaye; Toma, Henrique Eisi; Poliselli Farsky, Sandra Helena; Araki, Koiti

    2015-01-01

    Fully dispersible, cationic ultrasmall (7 nm diameter) superparamagnetic iron oxide nanoparticles, exhibiting high relaxivity (178 mM−1s−1 in 0.47 T) and no acute or subchronic toxicity in Wistar rats, were studied and their suitability as contrast agents for magnetic resonance imaging and material for development of new diagnostic and treatment tools demonstrated. After intravenous injection (10 mg/kg body weight), they circulated throughout the vascular system causing no microhemorrhage or thrombus, neither inflammatory processes at the mesentery vascular bed and hepatic sinusoids (leukocyte rolling, adhesion, or migration as evaluated by intravital microscopy), but having been spontaneously concentrated in the liver, spleen, and kidneys, they caused strong negative contrast. The nanoparticles are cleared from kidneys and bladder in few days, whereas the complete elimination from liver and spleen occurred only after 4 weeks. Ex vivo studies demonstrated that cationic ultrasmall superparamagnetic iron oxide nanoparticles caused no effects on hepatic and renal enzymes dosage as well as on leukocyte count. In addition, they were readily concentrated in rat thigh by a magnet showing its potential as magnetically targeted carriers of therapeutic and diagnostic agents. Summarizing, cationic ultrasmall superparamagnetic iron oxide nanoparticles are nontoxic and efficient magnetic resonance imaging contrast agents useful as platform for the development of new materials for application in theranostics. PMID:26251595

  16. On-chip measurements of Brownian relaxation of magnetic beads with diameters from 10 nm to 250 nm

    DEFF Research Database (Denmark)

    Østerberg, Frederik Westergaard; Rizzi, Giovanni; Hansen, Mikkel Fougt

    2013-01-01

    We demonstrate the use of planar Hall effect magnetoresistive sensors for AC susceptibility measurements of magnetic beads with frequencies ranging from DC to 1 MHz. This wide frequency range allows for measuring Brownian relaxation of magnetic beads with diameters ranging from 10 nm to 250 nm....... Brownian relaxation is measured for six different magnetic bead types and their hydrodynamic diameters are determined. The hydrodynamic diameters are found to be within 40% of the nominal bead diameters. We discuss the applicability of the different bead types for volume-based biosensing with respect...... to sedimentation, magnetic trapping, and signal per bead. Among the investigated beads, we conclude that the beads with a nominal diameter of 80 nm are best suited for future on-chip volume-based biosensing experiments using planar Hall effect sensors....

  17. Parallel RNA extraction using magnetic beads and a droplet array.

    Science.gov (United States)

    Shi, Xu; Chen, Chun-Hong; Gao, Weimin; Chao, Shih-Hui; Meldrum, Deirdre R

    2015-02-21

    Nucleic acid extraction is a necessary step for most genomic/transcriptomic analyses, but it often requires complicated mechanisms to be integrated into a lab-on-a-chip device. Here, we present a simple, effective configuration for rapidly obtaining purified RNA from low concentration cell medium. This Total RNA Extraction Droplet Array (TREDA) utilizes an array of surface-adhering droplets to facilitate the transportation of magnetic purification beads seamlessly through individual buffer solutions without solid structures. The fabrication of TREDA chips is rapid and does not require a microfabrication facility or expertise. The process takes less than 5 minutes. When purifying mRNA from bulk marine diatom samples, its repeatability and extraction efficiency are comparable to conventional tube-based operations. We demonstrate that TREDA can extract the total mRNA of about 10 marine diatom cells, indicating that the sensitivity of TREDA approaches single-digit cell numbers.

  18. A dynamic bead-based microarray for parallel DNA detection

    International Nuclear Information System (INIS)

    Sochol, R D; Lin, L; Casavant, B P; Dueck, M E; Lee, L P

    2011-01-01

    A microfluidic system has been designed and constructed by means of micromachining processes to integrate both microfluidic mixing of mobile microbeads and hydrodynamic microbead arraying capabilities on a single chip to simultaneously detect multiple bio-molecules. The prototype system has four parallel reaction chambers, which include microchannels of 18 × 50 µm 2 cross-sectional area and a microfluidic mixing section of 22 cm length. Parallel detection of multiple DNA oligonucleotide sequences was achieved via molecular beacon probes immobilized on polystyrene microbeads of 16 µm diameter. Experimental results show quantitative detection of three distinct DNA oligonucleotide sequences from the Hepatitis C viral (HCV) genome with single base-pair mismatch specificity. Our dynamic bead-based microarray offers an effective microfluidic platform to increase parallelization of reactions and improve microbead handling for various biological applications, including bio-molecule detection, medical diagnostics and drug screening

  19. Echicetin coated polystyrene beads: a novel tool to investigate GPIb-specific platelet activation and aggregation.

    Directory of Open Access Journals (Sweden)

    Alexey Navdaev

    Full Text Available von Willebrand factor/ristocetin (vWF/R induces GPIb-dependent platelet agglutination and activation of αIIbβ3 integrin, which also binds vWF. These conditions make it difficult to investigate GPIb-specific signaling pathways in washed platelets. Here, we investigated the specific mechanisms of GPIb signaling using echicetin-coated polystyrene beads, which specifically activate GPIb. We compared platelet activation induced by echicetin beads to vWF/R. Human platelets were stimulated with polystyrene beads coated with increasing amounts of echicetin and platelet activation by echicetin beads was then investigated to reveal GPIb specific signaling. Echicetin beads induced αIIbβ3-dependent aggregation of washed platelets, while under the same conditions vWF/R treatment led only to αIIbβ3-independent platelet agglutination. The average distance between the echicetin molecules on the polystyrene beads must be less than 7 nm for full platelet activation, while the total amount of echicetin used for activation is not critical. Echicetin beads induced strong phosphorylation of several proteins including p38, ERK and PKB. Synergistic signaling via P2Y12 and thromboxane receptor through secreted ADP and TxA2, respectively, were important for echicetin bead triggered platelet activation. Activation of PKG by the NO/sGC/cGMP pathway inhibited echicetin bead-induced platelet aggregation. Echicetin-coated beads are powerful and reliable tools to study signaling in human platelets activated solely via GPIb and GPIb-triggered pathways.

  20. Effect of Heat Input on Geometry of Austenitic Stainless Steel Weld Bead on Low Carbon Steel

    Science.gov (United States)

    Saha, Manas Kumar; Hazra, Ritesh; Mondal, Ajit; Das, Santanu

    2018-05-01

    Among different weld cladding processes, gas metal arc welding (GMAW) cladding becomes a cost effective, user friendly, versatile method for protecting the surface of relatively lower grade structural steels from corrosion and/or erosion wear by depositing high grade stainless steels onto them. The quality of cladding largely depends upon the bead geometry of the weldment deposited. Weld bead geometry parameters, like bead width, reinforcement height, depth of penetration, and ratios like reinforcement form factor (RFF) and penetration shape factor (PSF) determine the quality of the weld bead geometry. Various process parameters of gas metal arc welding like heat input, current, voltage, arc travel speed, mode of metal transfer, etc. influence formation of bead geometry. In the current experimental investigation, austenite stainless steel (316) weld beads are formed on low alloy structural steel (E350) by GMAW using 100% CO2 as the shielding gas. Different combinations of current, voltage and arc travel speed are chosen so that heat input increases from 0.35 to 0.75 kJ/mm. Nine number of weld beads are deposited and replicated twice. The observations show that weld bead width increases linearly with increase in heat input, whereas reinforcement height and depth of penetration do not increase with increase in heat input. Regression analysis is done to establish the relationship between heat input and different geometrical parameters of weld bead. The regression models developed agrees well with the experimental data. Within the domain of the present experiment, it is observed that at higher heat input, the weld bead gets wider having little change in penetration and reinforcement; therefore, higher heat input may be recommended for austenitic stainless steel cladding on low alloy steel.

  1. Echicetin Coated Polystyrene Beads: A Novel Tool to Investigate GPIb-Specific Platelet Activation and Aggregation

    Science.gov (United States)

    Petunin, Alexey; Clemetson, Kenneth J.; Gambaryan, Stepan; Walter, Ulrich

    2014-01-01

    von Willebrand factor/ristocetin (vWF/R) induces GPIb-dependent platelet agglutination and activation of αIIbβ3 integrin, which also binds vWF. These conditions make it difficult to investigate GPIb-specific signaling pathways in washed platelets. Here, we investigated the specific mechanisms of GPIb signaling using echicetin-coated polystyrene beads, which specifically activate GPIb. We compared platelet activation induced by echicetin beads to vWF/R. Human platelets were stimulated with polystyrene beads coated with increasing amounts of echicetin and platelet activation by echicetin beads was then investigated to reveal GPIb specific signaling. Echicetin beads induced αIIbβ3-dependent aggregation of washed platelets, while under the same conditions vWF/R treatment led only to αIIbβ3-independent platelet agglutination. The average distance between the echicetin molecules on the polystyrene beads must be less than 7 nm for full platelet activation, while the total amount of echicetin used for activation is not critical. Echicetin beads induced strong phosphorylation of several proteins including p38, ERK and PKB. Synergistic signaling via P2Y12 and thromboxane receptor through secreted ADP and TxA2, respectively, were important for echicetin bead triggered platelet activation. Activation of PKG by the NO/sGC/cGMP pathway inhibited echicetin bead-induced platelet aggregation. Echicetin-coated beads are powerful and reliable tools to study signaling in human platelets activated solely via GPIb and GPIb-triggered pathways. PMID:24705415

  2. Floating-bioadhesive gastroretentive Caesalpinia pulcherrima-based beads of amoxicillin trihydrate for Helicobacter pylori eradication.

    Science.gov (United States)

    Thombre, Nilima A; Gide, Paraag S

    2016-01-01

    An oral dosage form containing floating bioadhesive gastroretentive microspheres forms a stomach-specific drug delivery system for the treatment of Helicobacter pylori. To prepare and evaluate controlled release floating bioadhesive gastroretentive chitosan-coated amoxicillin trihydrate-loaded Caesalpinia pulcherrima galactomannan (CPG)-alginate beads (CCA-CPG-A), for H. pylori eradication. CCA-CPG-A beads were prepared by ionotropic gelation, using 2(3) factorial design with quantity of drug, combination of CPG with sodium alginate and concentration of calcium chloride as variables. Beads facilitated mucoadhesion to gastric mucosa with floating nature caused by chitosan coating for wide distribution throughout GIT. Developed beads were evaluated for characteristics like beads size-morphology, entrapment efficiency, DSC, XRD, FTIR, swelling ratio, in vitro mucoadhesion, in vitro drug release, in vitro floating and in vitro H. pylori growth inhibition studies. CCA-CPG-A beads were studied in Wistar rats for in vivo gastric mucoadhesion, in vivo H. pylori growth inhibition studies using PCR amplification of isolated DNA, rapid urease test. Developed beads possess drug release of 79-92%, entrapment efficiency of 65-89%, mucoadhesion of 61-89%. In vivo mucoadhesion study showed more than 85% mucoadhesion of beads even after 7th hour. In vitro-in vivo growth inhibition study showed complete eradication of H. pylori. CPG-alginate and chitosan in beads interacts with gastric mucosubstrate surface for prolonged gastric residence with floating bioadhesion mechanism for H. pylori eradication in rats. Floating bioadhesive CCA-CPG-A beads offer a promising drug delivery system for H. pylori eradication at lower dose, reduced adverse effect and enhance bioavailability.

  3. Antimony sorption properties of chitosan - nano TiO2 composite beads

    International Nuclear Information System (INIS)

    Nishad, Padala Abdul; Bhaskarapillai, Anupkumar; Velmurugan, Sankaralingam

    2015-01-01

    Routine decontamination campaigns of nuclear reactors are generally effective in removing various radionuclides such as cobalt, caesium, etc., and bring down the radiation field. However, during some of the decontamination campaigns, the radiation field at some surfaces was seen to have actually gone up. This was found to be due to lack of removal of antimony isotopes by the regular ion exchange resins used, which subsequently deposited over out of core surfaces leading to increased radiation field on those surfaces. Thus there exists a need for efficient antimony removal system. We have synthesised nano titania impregnated - epichlorohydrin crosslinked chitosan beads, which were found to have high sorption capacity for antimony. The beads, which were synthesised in formats suitable for large scale (column mode) applications, were shown to be effective sorbent of antimony in both +3 and +5 oxidation states. The sorbent exhibited complete removal of antimony from its aqueous solutions of concentration ranging from 150 ppb to 120 ppm. In order to understand the sorption mechanism and to fine tune the bead composition, the effect of crosslinker concentration used during the synthesis on the swelling and sorption properties of the beads was investigated in detail. The variation effected significant changes in physical parameters such as bead diameter, swelling ratio, equilibrium water content and true wet density. Sorption capacity, unlike with regular resins, was found to increase with increase in crosslinker amount. The antimony sorption capacity of the crosslinked beads prepared by crosslinking 0.3 g uncrosslinked beads with 6.4 mmol epichlorohydrin (crosslinker) was 493 μmol/g. Non-crosslinked beads showed a capacity of 75 μmol/g, while the crosslinked beads made with the least amount of crosslinker (0.64 mmol per 0.3 g beads) showed a capacity of 133 μmol/g. These results indicate the possible involvement of the crosslinker in the sorption. (author)

  4. [Evaluation of TB-beads assay utilizing the technique of magnetic beads--an innovative assay method for detection of acid fast bacilli].

    Science.gov (United States)

    Ohkuma, Masanori; Ikeda, Katsuyoshi; Obayashi, Konen; Ando, Yukio; Koriyama, Toyoyasu; Kimu, Minhi; Hirose, Nobuyuki; Nagasawa, Zenzo; Miyamoto, Hiroshi

    2012-01-01

    The centrifuge method with the use of Semi-Alkalin Proteinase (SAP) and NALC-NaOH, recommended by the "2007 edition of the assay guideline for detection of Mycobacterium tuberculosis," has significantly contributed to improving the sensitivities and specificities of both smear and culture tests for detection of acid fast bacilli (AFB). However, this method poses some challenges in terms of its cumbersome and time-consuming assay protocol. "TB-beads (Kyokuto Pharmaceutical Industrial Co., Ltd.)" is a newly-developed method for detection of AFB utilizing magnetic beads. We evaluated the quality of this method in comparison with the centrifuge method, focusing on the results of smear and culture tests. This evaluation study was conducted using both 5 positive and 5 negative sputum samples. The sensitivity of TB-beads for fluorescent smear tests, conducted using "Acri-stain," was almost the same as that of the centrifuge method. One advantage of TB-beads, however, was that it was very convenient to practice microscopic observation due to the clear background of the smeared glass slides. The comparison of the contamination rates between the two methods showed that TB-beads suggested significantly lower contamination rates. The centrifuge method resulted in 50% and 60% of contamination rates for HK Semisolid Isolation Medium and BacT/ALERT MP, respectively. On the other hand, the contamination rates of TB-beads for both of the culture methods were only 10%. With regard to the 5 positive sputum samples, the comparison of the detection rates between the centrifuge and TB-Beads method was made utilizing Myco Acid, Ogawa K, and BacT/ALERT MP. The TB-Beads method suggested higher detection rates for Myco Acid and Ogawa K, while there were no significant differences between the two methods for BacT/ALERT MP (16-23 days). TB-beads is an easy method that allows to simplify the process of smear tests, and contributes to significantly reducing the contamination rate of culture

  5. Neutron activation analysis of AD 1660-1930 European copper-coloured blue glass trade beads from Ontario, Canada

    International Nuclear Information System (INIS)

    Kenyon, I.; Hancock, R.G.V.; Aufreiter, S.

    1995-01-01

    Blue glass trade beads from well-dated late seventeenth- to early twentieth-century sites and collections have been analysed non-destructively by instrumental neutron activation analysis. The beads display enough variations in their elemental contents to allow us to characterize the different chemistries. The implication of these results is that similar chemical analyses of blue beads from undated archaeological sites may be used to help date the sites, since each bead chemistry has a specific earliest period. (author)

  6. Preparation of Macroporous Poly (vinyl alcohol-co-triallyl isocyanurate) Beads Bearing Aminocarboxylic Acid as Functional Groups by Suspension Polymerization

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Macroporous poly (vinyl acetate-co-triallyl isocyanurate) beads were prepared with suspension polymerization method. The copolymer beads were then transformed into poly (vinyl alcohol-co-triallyl isocyanurate) by ester exchange reaction. Aminocarboxylic acids were immobilized on the copolymer beads by the esterification of hydroxyl groups with diethyl-lenetriaminepentaacetic bisanhydride. The weak acid exchange capacities, specific surface areas and mean pore diameters of the resultant resin beads were measured.

  7. Development and evaluation of alginate-chitosan gastric floating beads loading with oxymatrine solid dispersion.

    Science.gov (United States)

    Liu, Yanhua; Chen, Lihong; Zhou, Chengming; Yang, Jianhong; Hou, Yanhui; Wang, Wenping

    2016-01-01

    Oxymatrine (OM) can be metabolized to matrine in gastrointestinal ileocecal valve after oral administration, which affects pharmacological activity and reduce bioavailability of OM. A type of multiple-unit alginate-chitosan (Alg-Cs) floating beads was prepared by the ionotropic gelation method for gastroretention delivery of OM. A solid dispersion technique was applied and incorporated into beads to enhance the OM encapsulation efficiency (EE) and sustain the drug release. The surface morphology and internal hollow structure of beads were evaluated using optical microscopy and scanning electron microscopy (SEM). The developed Alg-Cs beads were spherical in shape with hollow internal structure and had particle size of 3.49 ± 0.09 mm and 1.33 ± 0.09 mm for wet and dried beads. Over 84% of the optimized OM solid dispersion-loaded Alg-Cs beads were able to continuously float over the simulated gastric fluid for 12 h in vitro. The OM solid dispersion-loaded Alg-Cs beads showed drug EE of 67.07%, which was much higher than that of beads loading with pure OM. Compared with the immediate release of OM capsules and pure OM-loaded beads, the release of OM from solid dispersion-loaded Alg-Cs beads was in a sustained-release manner for 12 h. Prolonged gastric retention time of over 8.5 h was achieved for OM solid dispersion-loaded Alg-Cs floating beads in healthy rabbit in in vivo floating ability evaluated by X-ray imaging. The developed Alg-Cs beads loading with OM solid dispersion displayed excellent performance features characterized by excellent gastric floating ability, high drug EE and sustained-release pattern. The study illustrated the potential use of Alg-Cs floating beads combined with the solid dispersion technique for prolonging gastric retention and sustaining release of OM, which could provide a promising drug delivery system for gastric-specific delivery of OM for bioavailability enhancement.

  8. 77 FR 12311 - Guidance for Industry on Size of Beads in Drug Products Labeled for Sprinkle; Availability

    Science.gov (United States)

    2012-02-29

    ...] Guidance for Industry on Size of Beads in Drug Products Labeled for Sprinkle; Availability AGENCY: Food and... the availability of a guidance for industry entitled ``Size of Beads in Drug Products Labeled for... Evaluation and Research's (CDER's) current thinking on appropriate size ranges for beads in drug products...

  9. 76 FR 3144 - Draft Guidance for Industry on Size of Beads in Drug Products Labeled for Sprinkle; Availability

    Science.gov (United States)

    2011-01-19

    ...] Draft Guidance for Industry on Size of Beads in Drug Products Labeled for Sprinkle; Availability AGENCY... announcing the availability of a draft guidance for industry entitled ``Size of Beads in Drug Products... Evaluation and Research's (CDER's) current thinking on appropriate size ranges for beads in drug products...

  10. Visualization of antigen-specific human cytotoxic T lymphocytes labeled with superparamagnetic iron-oxide particles

    Energy Technology Data Exchange (ETDEWEB)

    Beer, Ambros J. [Technical University of Munich (TUM), Department of Nuclear Medicine, Klinikum rechts der Isar, Munich (Germany); Holzapfel, Konstantin; Settles, Marcus; Rummeny, Ernst J. [Technical University of Munich, Department of Radiology, Klinikum rechts der Isar, Munich (Germany); Neudorfer, Juliana; Kroenig, Holger; Peschel, Christian; Bernhard, Helga [TUM, Munich, Department of Hematology/Oncology, Klinikum rechts der Isar, Munich (Germany); Piontek, Guido; Schlegel, Juergen [TUM, Munich, Division of Neuropathology, Institute of Pathology, Klinikum rechts der Isar, Munich (Germany)

    2008-06-15

    New technologies are needed to characterize the migration and survival of antigen-specific T cells in vivo. In this study, we developed a novel technique for the labeling of human cytotoxic T lymphocytes with superparamagnetic iron-oxide particles and the subsequent depiction with a conventional 1.5-T magnetic resonance scanner. Antigen-specific CD8{sup +} T lymphocytes were labeled with ferucarbotran by lipofection. The uptake of ferucarbotran was confirmed by immunofluorescence microscopy using a dextran-specific antibody, and the intracellular enrichment of iron was measured by atomic absorption spectrometry. The imaging of T cells was performed by magnetic resonance on day 0, 2, 7 and 14 after the labeling procedure. On day 0 and 2 post labeling, a pronounced shortening of T2*-relaxation times was observed, which diminished after 7 days and was not detectable anymore after 14 days, probably due to the retained mitotic activity of the labeled T cells. Of importance, the antigen-specific cytolytic activity of the T cells was preserved following ferucarbotran labeling. Efficient ferucarbotran labeling of functionally active T lymphocytes and their detection by magnetic resonance imaging allows the in vivo monitoring of T cells and, subsequently, will impact the further development of T cell-based therapies. (orig.)

  11. Visualization of antigen-specific human cytotoxic T lymphocytes labeled with superparamagnetic iron-oxide particles

    International Nuclear Information System (INIS)

    Beer, Ambros J.; Holzapfel, Konstantin; Settles, Marcus; Rummeny, Ernst J.; Neudorfer, Juliana; Kroenig, Holger; Peschel, Christian; Bernhard, Helga; Piontek, Guido; Schlegel, Juergen

    2008-01-01

    New technologies are needed to characterize the migration and survival of antigen-specific T cells in vivo. In this study, we developed a novel technique for the labeling of human cytotoxic T lymphocytes with superparamagnetic iron-oxide particles and the subsequent depiction with a conventional 1.5-T magnetic resonance scanner. Antigen-specific CD8 + T lymphocytes were labeled with ferucarbotran by lipofection. The uptake of ferucarbotran was confirmed by immunofluorescence microscopy using a dextran-specific antibody, and the intracellular enrichment of iron was measured by atomic absorption spectrometry. The imaging of T cells was performed by magnetic resonance on day 0, 2, 7 and 14 after the labeling procedure. On day 0 and 2 post labeling, a pronounced shortening of T2*-relaxation times was observed, which diminished after 7 days and was not detectable anymore after 14 days, probably due to the retained mitotic activity of the labeled T cells. Of importance, the antigen-specific cytolytic activity of the T cells was preserved following ferucarbotran labeling. Efficient ferucarbotran labeling of functionally active T lymphocytes and their detection by magnetic resonance imaging allows the in vivo monitoring of T cells and, subsequently, will impact the further development of T cell-based therapies. (orig.)

  12. Synthesis, characterization and theranostic evaluation of Indium-111 labeled multifunctional superparamagnetic iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Zolata, Hamidreza; Abbasi Davani, Fereydoun; Afarideh, Hossein

    2015-01-01

    Indium-111 labeled, Trastuzumab-Doxorubicin Conjugated, and APTES-PEG coated magnetic nanoparticles were designed for tumor targeting, drug delivery, controlled drug release, and dual-modal tumor imaging. Superparamagnetic iron oxide nanoparticles (SPIONs) were synthesized by thermal decomposition method to obtain narrow size particles. To increase SPIONs circulation time in blood and decrease its cytotoxicity in healthy tissues, SPIONs surface was modified with 3-Aminopropyltriethoxy Silane (APTES) and then were functionalized with N-Hydroxysuccinimide (NHS) ester of Polyethylene Glycol Maleimide (NHS-PEG-Mal) to conjugate with thiolated 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene-3,6, 9,-triacetic acid (PCTA) bifunctional chelator (BFC) and Trastuzumab antibody. In order to tumor SPECT/MR imaging, SPIONs were labeled with Indium-111 (T 1/2 = 2.80d). NHS ester of monoethyl malonate (MEM-NHS) was used for conjugation of Doxorubicin (DOX) chemotherapeutic agent onto SPIONs surface. Mono-Ethyl Malonate allows DOX molecules to be attached to SPIONs via pH-sensitive hydrazone bonds which lead to controlled drug release in tumor region. Active and passive tumor targeting were achieved through incorporated anti-HER2 (Trastuzumab) antibody and EPR effect of solid tumors for nanoparticles respectively. In addition to in vitro assessments of modified SPIONs in SKBR3 cell lines, their theranostic effects were evaluated in HER2 + breast tumor bearing BALB/c mice via biodistribution study, dual-modal molecular imaging and tumor diameter measurements

  13. Quantification of the internalization patterns of superparamagnetic iron oxide nanoparticles with opposite charge

    Directory of Open Access Journals (Sweden)

    Schweiger Christoph

    2012-07-01

    Full Text Available Abstract Time-resolved quantitative colocalization analysis is a method based on confocal fluorescence microscopy allowing for a sophisticated characterization of nanomaterials with respect to their intracellular trafficking. This technique was applied to relate the internalization patterns of nanoparticles i.e. superparamagnetic iron oxide nanoparticles with distinct physicochemical characteristics with their uptake mechanism, rate and intracellular fate. The physicochemical characterization of the nanoparticles showed particles of approximately the same size and shape as well as similar magnetic properties, only differing in charge due to different surface coatings. Incubation of the cells with both nanoparticles resulted in strong differences in the internalization rate and in the intracellular localization depending on the charge. Quantitative and qualitative analysis of nanoparticles-organelle colocalization experiments revealed that positively charged particles were found to enter the cells faster using different endocytotic pathways than their negative counterparts. Nevertheless, both nanoparticles species were finally enriched inside lysosomal structures and their efficiency in agarose phantom relaxometry experiments was very similar. This quantitative analysis demonstrates that charge is a key factor influencing the nanoparticle-cell interactions, specially their intracellular accumulation. Despite differences in their physicochemical properties and intracellular distribution, the efficiencies of both nanoparticles as MRI agents were not significantly different.

  14. Superparamagnetic iron oxide nanoparticles labeling of bone marrow stromal (mesenchymal cells does not affect their "stemness".

    Directory of Open Access Journals (Sweden)

    Arun Balakumaran

    2010-07-01

    Full Text Available Superparamagnetic iron oxide nanoparticles (SPION are increasingly used to label human bone marrow stromal cells (BMSCs, also called "mesenchymal stem cells" to monitor their fate by in vivo MRI, and by histology after Prussian blue (PB staining. SPION-labeling appears to be safe as assessed by in vitro differentiation of BMSCs, however, we chose to resolve the question of the effect of labeling on maintaining the "stemness" of cells within the BMSC population in vivo. Assays performed include colony forming efficiency, CD146 expression, gene expression profiling, and the "gold standard" of evaluating bone and myelosupportive stroma formation in vivo in immuncompromised recipients. SPION-labeling did not alter these assays. Comparable abundant bone with adjoining host hematopoietic cells were seen in cohorts of mice that were implanted with SPION-labeled or unlabeled BMSCs. PB+ adipocytes were noted, demonstrating their donor origin, as well as PB+ pericytes, indicative of self-renewal of the stem cell in the BMSC population. This study confirms that SPION labeling does not alter the differentiation potential of the subset of stem cells within BMSCs.

  15. Magnetic anisotropy considerations in magnetic force microscopy studies of single superparamagnetic nanoparticles

    International Nuclear Information System (INIS)

    Nocera, Tanya M; Agarwal, Gunjan; Chen Jun; Murray, Christopher B

    2012-01-01

    In recent years, superparamagnetic nanoparticles (SPNs) have become increasingly important in applications ranging from solid state memory devices to biomedical diagnostic and therapeutic tools. However, detection and characterization of the small and unstable magnetic moment of an SPN at the single particle level remains a challenge. Further, depending on their physical shape, crystalline structure or orientation, SPNs may also possess magnetic anisotropy, which can govern the extent to which their magnetic moments can align with an externally applied magnetic field. Here, we demonstrate how we can exploit the magnetic anisotropy of SPNs to enable uniform, highly-sensitive detection of single SPNs using magnetic force microscopy (MFM) in ambient air. Superconducting quantum interference device magnetometry and analytical transmission electron microscopy techniques are utilized to characterize the collective magnetic behavior, morphology and composition of the SPNs. Our results show how the consideration of magnetic anisotropy can enhance the ability of MFM to detect single SPNs at ambient room temperature with high force sensitivity and spatial resolution. (paper)

  16. Synthesis, characterization and antibacterial activity of superparamagnetic nanoparticles modified with glycol chitosan

    International Nuclear Information System (INIS)

    Stephen Inbaraj, Baskaran; Tsai, Tsung-Yu; Chen, Bing-Huei

    2012-01-01

    Iron oxide nanoparticles (IONPs) were synthesized by coprecipitation of iron salts in alkali media followed by coating with glycol chitosan (GC-coated IONPs). Both bare and GC-coated IONPs were subsequently characterized and evaluated for their antibacterial activity. Comparison of Fourier transform infrared spectra and thermogravimetric data of bare and GC-coated IONPs confirmed the presence of GC coating on IONPs. Magnetization curves showed that both bare and GC-coated IONPs are superparamagnetic and have saturation magnetizations of 70.3 and 59.8 emu g −1 , respectively. The IONP size was measured as ∼8–9 nm by transmission electron microscopy, and their crystal structure was assigned to magnetite from x-ray diffraction patterns. Both bare and GC-coated IONPs inhibited the growths of Escherichia coli ATCC 8739 and Salmonella enteritidis SE 01 bacteria better than the antibiotics linezolid and cefaclor, as evaluated by the agar dilution assay. GC-coated IONPs showed higher potency against E. coli O157:H7 and Staphylococcus aureus ATCC 10832 than bare IONPs. Given their biocompatibility and antibacterial properties, GC-coated IONPs are a potential nanomaterial for in vivo applications.

  17. Oxidative stress response in neural stem cells exposed to different superparamagnetic iron oxide nanoparticles.

    Science.gov (United States)

    Pongrac, Igor M; Pavičić, Ivan; Milić, Mirta; Brkić Ahmed, Lada; Babič, Michal; Horák, Daniel; Vinković Vrček, Ivana; Gajović, Srećko

    2016-01-01

    Biocompatibility, safety, and risk assessments of superparamagnetic iron oxide nanoparticles (SPIONs) are of the highest priority in researching their application in biomedicine. One improvement in the biological properties of SPIONs may be achieved by different functionalization and surface modifications. This study aims to investigate how a different surface functionalization of SPIONs - uncoated, coated with d-mannose, or coated with poly-l-lysine - affects biocompatibility. We sought to investigate murine neural stem cells (NSCs) as important model system for regenerative medicine. To reveal the possible mechanism of toxicity of SPIONs on NSCs, levels of reactive oxygen species, intracellular glutathione, mitochondrial membrane potential, cell-membrane potential, DNA damage, and activities of SOD and GPx were examined. Even in cases where reactive oxygen species levels were significantly lowered in NSCs exposed to SPIONs, we found depleted intracellular glutathione levels, altered activities of SOD and GPx, hyperpolarization of the mitochondrial membrane, dissipated cell-membrane potential, and increased DNA damage, irrespective of the surface coating applied for SPION stabilization. Although surface coating should prevent the toxic effects of SPIONs, our results showed that all of the tested SPION types affected the NSCs similarly, indicating that mitochondrial homeostasis is their major cellular target. Despite the claimed biomedical benefits of SPIONs, the refined determination of their effects on various cellular functions presented in this work highlights the need for further safety evaluations. This investigation helps to fill the knowledge gaps on the criteria that should be considered in evaluating the biocompatibility and safety of novel nanoparticles.

  18. Ultra-small superparamagnetic particles of iron oxide in magnetic resonance imaging of cardiovascular disease

    Directory of Open Access Journals (Sweden)

    Stirrat CG

    2014-10-01

    Full Text Available Colin G Stirrat,1 Alex T Vesey,1 Olivia MB McBride,1 Jennifer MJ Robson,1 Shirjel R Alam,1 William A Wallace,2 Scott I Semple,1,3 Peter A Henriksen,1 David E Newby1 1British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK; 2Department of Pathology, University of Edinburgh, Edinburgh, UK; 3Clinical Research Imaging Centre, University of Edinburgh, Edinburgh, UK Abstract: Ultra-small superparamagnetic particles of iron oxide (USPIO are iron-oxide based contrast agents that enhance and complement in vivo magnetic resonance imaging (MRI by shortening T1, T2, and T2* relaxation times. USPIO can be employed to provide immediate blood pool contrast, or to act as subsequent markers of cellular inflammation through uptake by inflammatory cells. They can also be targeted to specific cell-surface markers using antibody or ligand labeling. This review will discuss the application of USPIO contrast in MRI studies of cardiovascular disease. Keywords: cardiac, aortic, MRI, USPIO, carotid, vascular, molecular imaging

  19. Multifunctional PEG-carboxylate copolymer coated superparamagnetic iron oxide nanoparticles for biomedical application

    Science.gov (United States)

    Illés, Erzsébet; Szekeres, Márta; Tóth, Ildikó Y.; Szabó, Ákos; Iván, Béla; Turcu, Rodica; Vékás, Ladislau; Zupkó, István; Jaics, György; Tombácz, Etelka

    2018-04-01

    Biocompatible magnetite nanoparticles (MNPs) were prepared by post-coating the magnetic nanocores with a synthetic polymer designed specifically to shield the particles from non-specific interaction with cells. Poly(ethylene glycol) methyl ether methacrylate (PEGMA) macromonomers and acrylic acid (AA) small molecular monomers were chemically coupled by quasi-living atom transfer radical polymerization (ATRP) to a comb-like copolymer, P(PEGMA-co-AA) designated here as P(PEGMA-AA). The polymer contains pendant carboxylate moieties near the backbone and PEG side chains. It is able to bind spontaneously to MNPs; stabilize the particles electrostatically via the carboxylate moieties and sterically via the PEG moieties; provide high protein repellency via the structured PEG layer; and anchor bioactive proteins via peptide bond formation with the free carboxylate groups. The presence of the P(PEGMA-AA) coating was verified in XPS experiments. The electrosteric (i.e., combined electrostatic and steric) stabilization is efficient down to pH 4 (at 10 mM ionic strength). Static magnetization and AC susceptibility measurements showed that the P(PEGMA-AA)@MNPs are superparamagnetic with a saturation magnetization value of 55 emu/g and that both single core nanoparticles and multicore structures are present in the samples. The multicore components make our product well suited for magnetic hyperthermia applications (SAR values up to 17.44 W/g). In vitro biocompatibility, cell internalization, and magnetic hyperthermia studies demonstrate the excellent theranostic potential of our product.

  20. Superparamagnetic behavior of Fe-doped SnO2 nanoparticles

    International Nuclear Information System (INIS)

    Hachisu, M.; Onuma, K.; Kondo, T.; Miike, K.; Miyasaka, T.; Mori, K.; Ichiyanagi, Y.

    2014-01-01

    SnO 2 is an n-type semiconductor with a wide band gap of 3.62 eV, and SnO 2 nanoparticles doped with magnetic ions are expected to realized new diluted magnetic semiconductors (DMSs). Realizing ferromagnetism at room temperature is important for spintronics device applications, and it is interesting that the magnetic properties of these DMS systems can be varied significantly by modifying the preparation methods or conditions. In this study, the magnetic properties of Fe-doped (3% and 5%) SnO 2 nanoparticles, prepared using our novel chemical preparation method and encapsulated in amorphous SiO 2 , were investigated. The particle size (1.8–16.9 nm) and crystal phase were controlled by the annealing temperature. X-ray diffraction confirmed a rutile SnO 2 single-phase structure for samples annealed at 1073–1373 K, and the composition was confirmed using X-ray fluorescence analysis. SQUID magnetometer measurements revealed superparamagnetic behavior of the 5%-Fe-doped sample at room temperature, although SnO 2 is known to be diamagnetic. Magnetization curves at 5 K indicated that the 3%-Fe-doped has a larger magnetization than that of the 5%-Fe-doped sample. We conclude that the magnetization of the 5%-Fe-doped sample decreased at 5 K due to the superexchange interaction between the antiferromagnetic coupling in the nanoparticle system

  1. Superparamagnetic behavior of Fe-doped SnO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Hachisu, M.; Onuma, K.; Kondo, T.; Miike, K.; Miyasaka, T.; Mori, K.; Ichiyanagi, Y. [Department of Physics, Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama, Kanagawa 240-8501 (Japan)

    2014-02-20

    SnO{sub 2} is an n-type semiconductor with a wide band gap of 3.62 eV, and SnO{sub 2} nanoparticles doped with magnetic ions are expected to realized new diluted magnetic semiconductors (DMSs). Realizing ferromagnetism at room temperature is important for spintronics device applications, and it is interesting that the magnetic properties of these DMS systems can be varied significantly by modifying the preparation methods or conditions. In this study, the magnetic properties of Fe-doped (3% and 5%) SnO{sub 2} nanoparticles, prepared using our novel chemical preparation method and encapsulated in amorphous SiO{sub 2}, were investigated. The particle size (1.8–16.9 nm) and crystal phase were controlled by the annealing temperature. X-ray diffraction confirmed a rutile SnO{sub 2} single-phase structure for samples annealed at 1073–1373 K, and the composition was confirmed using X-ray fluorescence analysis. SQUID magnetometer measurements revealed superparamagnetic behavior of the 5%-Fe-doped sample at room temperature, although SnO{sub 2} is known to be diamagnetic. Magnetization curves at 5 K indicated that the 3%-Fe-doped has a larger magnetization than that of the 5%-Fe-doped sample. We conclude that the magnetization of the 5%-Fe-doped sample decreased at 5 K due to the superexchange interaction between the antiferromagnetic coupling in the nanoparticle system.

  2. Superparamagnetic behavior of Fe-doped SnO2 nanoparticles

    Science.gov (United States)

    Hachisu, M.; Onuma, K.; Kondo, T.; Miike, K.; Miyasaka, T.; Mori, K.; Ichiyanagi, Y.

    2014-02-01

    SnO2 is an n-type semiconductor with a wide band gap of 3.62 eV, and SnO2 nanoparticles doped with magnetic ions are expected to realized new diluted magnetic semiconductors (DMSs). Realizing ferromagnetism at room temperature is important for spintronics device applications, and it is interesting that the magnetic properties of these DMS systems can be varied significantly by modifying the preparation methods or conditions. In this study, the magnetic properties of Fe-doped (3% and 5%) SnO2 nanoparticles, prepared using our novel chemical preparation method and encapsulated in amorphous SiO2, were investigated. The particle size (1.8-16.9 nm) and crystal phase were controlled by the annealing temperature. X-ray diffraction confirmed a rutile SnO2 single-phase structure for samples annealed at 1073-1373 K, and the composition was confirmed using X-ray fluorescence analysis. SQUID magnetometer measurements revealed superparamagnetic behavior of the 5%-Fe-doped sample at room temperature, although SnO2 is known to be diamagnetic. Magnetization curves at 5 K indicated that the 3%-Fe-doped has a larger magnetization than that of the 5%-Fe-doped sample. We conclude that the magnetization of the 5%-Fe-doped sample decreased at 5 K due to the superexchange interaction between the antiferromagnetic coupling in the nanoparticle system.

  3. Intracellular trafficking of superparamagnetic iron oxide nanoparticles conjugated with TAT peptide: 3-dimensional electron tomography analysis

    Energy Technology Data Exchange (ETDEWEB)

    Nair, Baiju G.; Fukuda, Takahiro; Mizuki, Toru; Hanajiri, Tatsuro [Bio-Nano Electronics Research Centre, Toyo University, Saitama 350-8585 (Japan); Maekawa, Toru, E-mail: maekawa@toyo.jp [Bio-Nano Electronics Research Centre, Toyo University, Saitama 350-8585 (Japan)

    2012-05-18

    Highlights: Black-Right-Pointing-Pointer We study the intracellular localisation of TAT-SPIONs using 3-D electron tomography. Black-Right-Pointing-Pointer 3-D images of TAT-SPIONs in a cell are clearly shown. Black-Right-Pointing-Pointer Release of TAT-SPIONs from endocytic vesicles into the cytoplasm is clearly shown. -- Abstract: Internalisation of nanoparticles conjugated with cell penetrating peptides is a promising approach to various drug delivery applications. Cell penetrating peptides such as transactivating transcriptional activator (TAT) peptides derived from HIV-1 proteins are effective intracellular delivery vectors for a wide range of nanoparticles and pharmaceutical agents thanks to their amicable ability to enter cells and minimum cytotoxicity. Although different mechanisms of intracellular uptake and localisation have been proposed for TAT conjugated nanoparticles, it is necessary to visualise the particles on a 3-D plane in order to investigate the actual intracellular uptake and localisation. Here, we study the intracellular localisation and trafficking of TAT peptide conjugated superparamagnetic ion oxide nanoparticles (TAT-SPIONs) using 3-D electron tomography. 3-D tomograms clearly show the location of TAT-SPIONs in a cell and their slow release from the endocytic vesicles into the cytoplasm. The present methodology may well be utilised for further investigations of the behaviours of nanoparticles in cells and eventually for the development of nano drug delivery systems.

  4. Intracellular trafficking of superparamagnetic iron oxide nanoparticles conjugated with TAT peptide: 3-dimensional electron tomography analysis

    International Nuclear Information System (INIS)

    Nair, Baiju G.; Fukuda, Takahiro; Mizuki, Toru; Hanajiri, Tatsuro; Maekawa, Toru

    2012-01-01

    Highlights: ► We study the intracellular localisation of TAT-SPIONs using 3-D electron tomography. ► 3-D images of TAT-SPIONs in a cell are clearly shown. ► Release of TAT-SPIONs from endocytic vesicles into the cytoplasm is clearly shown. -- Abstract: Internalisation of nanoparticles conjugated with cell penetrating peptides is a promising approach to various drug delivery applications. Cell penetrating peptides such as transactivating transcriptional activator (TAT) peptides derived from HIV-1 proteins are effective intracellular delivery vectors for a wide range of nanoparticles and pharmaceutical agents thanks to their amicable ability to enter cells and minimum cytotoxicity. Although different mechanisms of intracellular uptake and localisation have been proposed for TAT conjugated nanoparticles, it is necessary to visualise the particles on a 3-D plane in order to investigate the actual intracellular uptake and localisation. Here, we study the intracellular localisation and trafficking of TAT peptide conjugated superparamagnetic ion oxide nanoparticles (TAT-SPIONs) using 3-D electron tomography. 3-D tomograms clearly show the location of TAT-SPIONs in a cell and their slow release from the endocytic vesicles into the cytoplasm. The present methodology may well be utilised for further investigations of the behaviours of nanoparticles in cells and eventually for the development of nano drug delivery systems.

  5. Selective in vitro anticancer effect of superparamagnetic iron oxide nanoparticles loaded in hyaluronan polymeric micelles.

    Science.gov (United States)

    Smejkalová, Daniela; Nešporová, Kristina; Huerta-Angeles, Gloria; Syrovátka, Jakub; Jirák, Daniel; Gálisová, Andrea; Velebný, Vladimír

    2014-11-10

    Due to its native origin, excellent biocompatibility and biodegradability, hyaluronan (HA) represents an attractive polymer for superparamagnetic iron oxide nanoparticles (SPION) coating. Herein, we report HA polymeric micelles encapsulating oleic acid coated SPIONs, having a hydrodynamic size of about 100 nm and SPION loading capacity of 1-2 wt %. The HA-SPION polymeric micelles were found to be selectively cytotoxic toward a number of human cancer cell lines, mainly those of colon adenocarcinoma (HT-29). The selective inhibition of cell growth was even observed when the SPION loaded HA polymeric micelles were incubated with a mixture of control and cancer cells. The selective in vitro inhibition could not be connected with an enhanced CD44 uptake or radical oxygen species formation and was rather connected with a different way of SPION intracellular release. While aggregated iron particles were visualized in control cells, nonaggregated solubilized iron oxide particles were detected in cancer cells. In vivo SPION accumulation in intramuscular tumor following an intravenous micelle administration was confirmed by magnetic resonance (MR) imaging and histological analysis. Having a suitable hydrodynamic size, high magnetic relaxivity, and being cancer specific and able to accumulate in vivo in tumors, SPION-loaded HA micelles represent a promising platform for theranostic applications.

  6. Accumulation and Toxicity of Superparamagnetic Iron Oxide Nanoparticles in Cells and Experimental Animals.

    Science.gov (United States)

    Jarockyte, Greta; Daugelaite, Egle; Stasys, Marius; Statkute, Urte; Poderys, Vilius; Tseng, Ting-Chen; Hsu, Shan-Hui; Karabanovas, Vitalijus; Rotomskis, Ricardas

    2016-08-19

    The uptake and distribution of negatively charged superparamagnetic iron oxide (Fe₃O₄) nanoparticles (SPIONs) in mouse embryonic fibroblasts NIH3T3, and magnetic resonance imaging (MRI) signal influenced by SPIONs injected into experimental animals, were visualized and investigated. Cellular uptake and distribution of the SPIONs in NIH3T3 after staining with Prussian Blue were investigated by a bright-field microscope equipped with digital color camera. SPIONs were localized in vesicles, mostly placed near the nucleus. Toxicity of SPION nanoparticles tested with cell viability assay (XTT) was estimated. The viability of NIH3T3 cells remains approximately 95% within 3-24 h of incubation, and only a slight decrease of viability was observed after 48 h of incubation. MRI studies on Wistar rats using a clinical 1.5 T MRI scanner were showing that SPIONs give a negative contrast in the MRI. The dynamic MRI measurements of the SPION clearance from the injection site shows that SPIONs slowly disappear from injection sites and only a low concentration of nanoparticles was completely eliminated within three weeks. No functionalized SPIONs accumulate in cells by endocytic mechanism, none accumulate in the nucleus, and none are toxic at a desirable concentration. Therefore, they could be used as a dual imaging agent: as contrast agents for MRI and for traditional optical biopsy by using Prussian Blue staining.

  7. Effects of superparamagnetic iron oxide nanoparticles on the longitudinal and transverse relaxation of hyperpolarized xenon gas

    Science.gov (United States)

    Burant, Alex; Antonacci, Michael; McCallister, Drew; Zhang, Le; Branca, Rosa Tamara

    2018-06-01

    SuperParamagnetic Iron Oxide Nanoparticles (SPIONs) are often used in magnetic resonance imaging experiments to enhance Magnetic Resonance (MR) sensitivity and specificity. While the effect of SPIONs on the longitudinal and transverse relaxation time of 1H spins has been well characterized, their effect on highly diffusive spins, like those of hyperpolarized gases, has not. For spins diffusing in linear magnetic field gradients, the behavior of the magnetization is characterized by the relative size of three length scales: the diffusion length, the structural length, and the dephasing length. However, for spins diffusing in non-linear gradients, such as those generated by iron oxide nanoparticles, that is no longer the case, particularly if the diffusing spins experience the non-linearity of the gradient. To this end, 3D Monte Carlo simulations are used to simulate the signal decay and the resulting image contrast of hyperpolarized xenon gas near SPIONs. These simulations reveal that signal loss near SPIONs is dominated by transverse relaxation, with little contribution from T1 relaxation, while simulated image contrast and experiments show that diffusion provides no appreciable sensitivity enhancement to SPIONs.

  8. Synthesis and characterization of superparamagnetic iron oxide nanoparticles as calcium-responsive MRI contrast agents

    International Nuclear Information System (INIS)

    Xu, Pengfei; Shen, Zhiwei; Zhang, Baolin; Wang, Jun; Wu, Renhua

    2016-01-01

    Highlights: • SPIONs were conjugated with EGTA by EDC/sulfo-NHS method. • The presence of Ca"2"+ induced the aggregation of EGTA-SPIONs. • The aggregation of EGTA-SPIONs increased the T2 relaxation time. • EGTA-SPIONs can be used for the calcium imaging with MRI. - Abstract: Superparamagnetic iron oxide nanoparticles (SPIONs) as T2 contrast agents have great potential to sense calcium ion (Ca"2"+) using magnetic resonance imaging (MRI). Here we prepared calcium-responsive SPIONs for MRI, formed by combining poly(ethylene glycol) (PEG) and polyethylenimine (PEI) coated iron oxide nanoparticle (PEI/PEG-SPIONs) contrast agents with the straightforward calcium-sensing compound EGTA (ethylene glycol tetraacetic acid). EGTA was conjugated onto PEI/PEG-SPIONs using EDC/sulfo-NHS method. EGTA-SPIONs were characterized using TEM, XPS, DSL, TGA and SQUIID. DSL results show that the SPIONs aggregate in the presence of Ca"2"+. MRI analyses indicate that the water proton T2 relaxation rates in HEPES suspensions of the EGTA-SPIONs significantly increase with the calcium concentration because the SPIONs aggregate in the presence of Ca"2"+. The T2 values decreased 25% when Ca"2"+ concentration decreased from 1.2 to 0.8 mM. The aggregation of EGTA-SPIONs could be reversed by EDTA. EGTA-SPIONs have potential as smart contrast agents for Ca"2"+-sensitive MRI.

  9. Brillouin Light Scattering from Magnetic Excitations in Superparamagnetic and Ferromagnetic Co-Al-O Granular Films

    Science.gov (United States)

    Yoshihara, Akira; Maeda, Toshiteru; Kawamura, Satoshi; Nakamura, Shintaro; Nojima, Tsutomu; Takeda, Yoshihiko; Ohnuma, Shigehiro

    2018-04-01

    A systematic study of Brillouin light scattering (BLS) from superparamagnetic (SPM) and ferromagnetic (FM) Co-Al-O granular films was performed under magnetic fields of up to 4.6 kOe in the standard backscattering geometry at room temperature. The SPM and FM boundary, defined as the Co composition at which the exchange field vanishes, was found to be located at xC(Co) = 59.3 ± 1.3 at. %. From FM films we observed a pair of bulk spin-wave peaks on both the positive- and negative-frequency sides and a surface localized Damon-Eshbach peak only on the positive-frequency side under the present scattering conditions. From SPM films, a pair of broader but propagative excitation peaks with asymmetric intensity were observed on both frequency sides in a spectrum. We performed a numerical analysis of the BLS spectrum by employing the theory developed by Camley and Mills (CM) while retaining dipole and exchange couplings for FM films and only dipole coupling for SPM films. The CM theory successfully reproduced the observed spectrum for both SPM and FM films. The SPM spectrum exhibits a singlet-doublet peak structure similarly to an FM SW spectrum. The SPM peak stems from the dipole-coupled larger-amplitude precession motion of the granule magnetic moment around the external-field-induced magnetization.

  10. Control of the interparticle spacing in superparamagnetic iron oxide nanoparticle clusters by surface ligand engineering

    Science.gov (United States)

    Dan, Wang; Bingbing, Lin; Taipeng, Shen; Jun, Wu; Fuhua, Hao; Chunchao, Xia; Qiyong, Gong; Huiru, Tang; Bin, Song; Hua, Ai

    2016-07-01

    Polymer-mediated self-assembly of superparamagnetic iron oxide (SPIO) nanoparticles allows modulation of the structure of SPIO nanocrystal cluster and their magnetic properties. In this study, dopamine-functionalized polyesters (DA-polyester) were used to directly control the magnetic nanoparticle spacing and its effect on magnetic resonance relaxation properties of these clusters was investigated. Monodisperse SPIO nanocrystals with different surface coating materials (poly(ɛ-caprolactone), poly(lactic acid)) of different molecular weights containing dopamine (DA) structure (DA-PCL2k, DA-PCL1k, DA-PLA1k)) were prepared via ligand exchange reaction, and these nanocrystals were encapsulated inside amphiphilic polymer micelles to modulate the SPIO nanocrystal interparticle spacing. Small-angle x-ray scattering (SAXS) was applied to quantify the interparticle spacing of SPIO clusters. The results demonstrated that the tailored magnetic nanoparticle clusters featured controllable interparticle spacing providing directly by the different surface coating of SPIO nanocrystals. Systematic modulation of SPIO nanocrystal interparticle spacing can regulate the saturation magnetization (M s) and T 2 relaxation of the aggregation, and lead to increased magnetic resonance (MR) relaxation properties with decreased interparticle spacing. Project supported by the National Key Basic Research Program of China (Grant No. 2013CB933903), the National Key Technology R&D Program of China (Grant No. 2012BAI23B08), and the National Natural Science Foundation of China (Grant Nos. 20974065, 51173117, and 50830107).

  11. Harmonic decomposition of magneto-optical signal from suspensions of superparamagnetic nanoparticles

    Science.gov (United States)

    Patterson, Cody; Syed, Maarij; Takemura, Yasushi

    2018-04-01

    Magnetic nanoparticles (MNPs) are widely used in biomedical applications. Characterizing dilute suspensions of superparamagnetic iron oxide nanoparticles (SPIONs) in bio-relevant media is particularly valuable for magnetic particle imaging, hyperthermia, drug delivery, etc. Here, we study dilute aqueous suspensions of single-domain magnetite nanoparticles using an AC Faraday rotation (FR) setup. The setup uses an oscillating magnetic field (800 Hz) which generates a multi-harmonic response. Each harmonic is collected and analyzed using the Fourier components of the theoretical signal determined by a Langevin-like magnetization. With this procedure, we determine the average magnetic moment per particle μ , particle number density n, and Verdet constant of the sample. The fitted values of μ and n are shown to be consistent across each harmonic. Additionally, we present the results of these parameters as n is varied. The large values of μ reveal the possibility of clustering as reported in other literature. This suggests that μ is representative of the average magnetic moment per cluster of nanoparticles. Multiple factors, including the external magnetic field, surfactant degradation, and laser absorption, can contribute to dynamic and long-term aggregation leading to FR signals that represent space- and time-averaged sample parameters. Using this powerful analysis procedure, future studies are aimed at determining the clustering mechanisms in this AC system and characterizing SPION suspensions at different frequencies and viscosities.

  12. Cellulase immobilization on superparamagnetic nanoparticles for reuse in cellulosic biomass conversion

    Directory of Open Access Journals (Sweden)

    Fernando Segato

    2016-07-01

    Full Text Available Current cellulosic biomass hydrolysis is based on the one-time use of cellulases. Cellulases immobilized on magnetic nanocarriers offer the advantages of magnetic separation and repeated use for continuous hydrolysis. Most immobilization methods focus on only one type of cellulase. Here, we report co-immobilization of two types of cellulases, β-glucosidase A (BglA and cellobiohydrolase D (CelD, on sub-20 nm superparamagnetic nanoparticles. The nanoparticles demonstrated 100% immobilization efficiency for both BglA and CelD. The total enzyme activities of immobilized BglA and CelD were up to 67.1% and 41.5% of that of the free cellulases, respectively. The immobilized BglA and CelD each retained about 85% and 43% of the initial immobilized enzyme activities after being recycled 3 and 10 times, respectively. The effects of pH and temperature on the immobilized cellulases were also investigated. Co-immobilization of BglA and CelD on MNPs is a promising strategy to promote synergistic action of cellulases while lowering enzyme consumption.

  13. Application of superparamagnetic microspheres for affinity adsorption and purification of glutathione

    International Nuclear Information System (INIS)

    Wang Qiang; Guan Yueping; Yang Mingzhu

    2012-01-01

    The superparamagnetic poly-(MA–DVB) microspheres with micron size were synthesized by the modified suspension polymerization method. Adsorption of glutathione by magnetic poly-(MA–DVB) microspheres with IDA-copper was investigated. The effect of solution pH value, affinity adsorption and desorption of glutathione was studied. The results showed that the optimum pH value for glutathione adsorption was found at pH=3.5, the maximum capacity for glutathione of magnetic poly-(MA–DVB) microspheres was estimated at 42.4 mg/g by fitting the experimental data to the Langmuir equation. The adsorption equilibrium of glutathione was obtained in about 10 min and the adsorbed glutathione was desorbed from the magnetic microspheres in about 30 min using NaCl buffer solution. The magnetic microspheres could be repeatedly utilized for the affinity adsorption of glutathione. - Highlights: ► The magnetic microsphere with surface IDA–Cu groups was synthesized. ► The magnetic microspheres were applied for adsorption of GSH. ► The adsorption–desorption of glutathione was investigated. ► The maximum adsorption capacity of GSH was fitted at 42.4 mg/g.

  14. Biodistribution and Clearance of Stable Superparamagnetic Maghemite Iron Oxide Nanoparticles in Mice Following Intraperitoneal Administration

    Directory of Open Access Journals (Sweden)

    Binh T. T. Pham

    2018-01-01

    Full Text Available Nanomedicine is an emerging field with great potential in disease theranostics. We generated sterically stabilized superparamagnetic iron oxide nanoparticles (s-SPIONs with average core diameters of 10 and 25 nm and determined the in vivo biodistribution and clearance profiles. Healthy nude mice underwent an intraperitoneal injection of these s-SPIONs at a dose of 90 mg Fe/kg body weight. Tissue iron biodistribution was monitored by atomic absorption spectroscopy and Prussian blue staining. Histopathological examination was performed to assess tissue toxicity. The 10 nm s-SPIONs resulted in higher tissue-iron levels, whereas the 25 nm s-SPIONs peaked earlier and cleared faster. Increased iron levels were detected in all organs and body fluids tested except for the brain, with notable increases in the liver, spleen, and the omentum. The tissue-iron returned to control or near control levels within 7 days post-injection, except in the omentum, which had the largest and most variable accumulation of s-SPIONs. No obvious tissue changes were noted although an influx of macrophages was observed in several tissues suggesting their involvement in s-SPION sequestration and clearance. These results demonstrate that the s-SPIONs do not degrade or aggregate in vivo and intraperitoneal administration is well tolerated, with a broad and transient biodistribution. In an ovarian tumor model, s-SPIONs were shown to accumulate in the tumors, highlighting their potential use as a chemotherapy delivery agent.

  15. Phosphate recovery from wastewater using engineered superparamagnetic particles modified with layered double hydroxide ion exchangers.

    Science.gov (United States)

    Drenkova-Tuhtan, Asya; Mandel, Karl; Paulus, Anja; Meyer, Carsten; Hutter, Frank; Gellermann, Carsten; Sextl, Gerhard; Franzreb, Matthias; Steinmetz, Heidrun

    2013-10-01

    An innovative nanocomposite material is proposed for phosphate recovery from wastewater using magnetic assistance. Superparamagnetic microparticles modified with layered double hydroxide (LDH) ion exchangers of various compositions act as phosphate adsorbers. Magnetic separation and chemical regeneration of the particles allows their reuse, leading to the successful recovery of phosphate. Based upon the preliminary screening of different LDH ion exchanger modifications for phosphate selectivity and uptake capacity, MgFe-Zr LDH coated magnetic particles were chosen for further characterization and application. The adsorption kinetics of phosphate from municipal wastewater was studied in dependence with particle concentration, contact time and pH. Adsorption isotherms were then determined for the selected particle system. Recovery of phosphate and regeneration of the particles was examined via testing a variety of desorption solutions. Reusability of the particles was demonstrated for 15 adsorption/desorption cycles. Adsorption in the range of 75-97% was achieved in each cycle after 1 h contact time. Phosphate recovery and enrichment was possible through repetitive application of the desorption solution. Finally, a pilot scale experiment was carried out by treating 125 L of wastewater with the particles in five subsequent 25 L batches. Solid-liquid separation on this scale was carried out with a high-gradient magnetic filter (HGMF). Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. A rapid method for the preparation of ultrapure, functional lysosomes using functionalized superparamagnetic iron oxide nanoparticles.

    Science.gov (United States)

    Walker, Mathew W; Lloyd-Evans, Emyr

    2015-01-01

    Lysosomes are an emerging and increasingly important cellular organelle. With every passing year, more novel proteins and key cellular functions are associated with lysosomes. Despite this, the methodologies for their purification have largely remained unchanged since the days of their discovery. With little advancement in this area, it is no surprise that analysis of lysosomal function has been somewhat stymied, largely in part by the change in buoyant densities that occur under conditions where lysosomes accumulate macromolecules. Such phenotypes are often associated with the lysosomal storage diseases but are increasingly being observed under conditions where lysosomal proteins or, in some cases, cellular functions associated with lysosomal proteins are being manipulated. These altered lysosomes poise a problem to the classical methods to purify lysosomes that are reliant largely on their correct sedimentation by density gradient centrifugation. Building upon a technique developed by others to purify lysosomes magnetically, we have developed a unique assay using superparamagnetic iron oxide nanoparticles (SPIONs) to purify high yields of ultrapure functional lysosomes from multiple cell types including the lysosomal storage disorders. Here we describe this method in detail, including the rationale behind using SPIONs, the potential pitfalls that can be avoided and the potential functional assays these lysosomes can be used for. Finally we also summarize the other methodologies and the exact reasons why magnetic purification of lysosomes is now the method of choice for lysosomal researchers. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Inkjet Printing of High Aspect Ratio Superparamagnetic SU-8 Microstructures with Preferential Magnetic Directions

    Directory of Open Access Journals (Sweden)

    Loïc Jacot-Descombes

    2014-08-01

    Full Text Available Structuring SU-8 based superparamagnetic polymer composite (SPMPC containing Fe3O4 nanoparticles by photolithography is limited in thickness due to light absorption by the nanoparticles. Hence, obtaining thicker structures requires alternative processing techniques. This paper presents a method based on inkjet printing and thermal curing for the fabrication of much thicker hemispherical microstructures of SPMPC. The microstructures are fabricated by inkjet printing the nanoparticle-doped SU-8 onto flat substrates functionalized to reduce the surface energy and thus the wetting. The thickness and the aspect ratio of the printed structures are further increased by printing the composite onto substrates with confinement pedestals. Fully crosslinked microstructures with a thickness up to 88.8 μm and edge angle of 112° ± 4° are obtained. Manipulation of the microstructures by an external field is enabled by creating lines of densely aggregated nanoparticles inside the composite. To this end, the printed microstructures are placed within an external magnetic field directly before crosslinking inducing the aggregation of dense Fe3O4 nanoparticle lines with in-plane and out-of-plane directions.

  18. Synthesis, characterization, and in vitro biological evaluation of highly stable diversely functionalized superparamagnetic iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Bhattacharya, Dipsikha; Sahu, Sumanta K.; Banerjee, Indranil; Das, Manasmita; Mishra, Debashish; Maiti, Tapas K.; Pramanik, Panchanan

    2011-01-01

    In this article, we report the design and synthesis of a series of well-dispersed superparamagnetic iron oxide nanoparticles (SPIONs) using chitosan as a surface modifying agent to develop a potential T 2 contrast probe for magnetic resonance imaging (MRI). The amine, carboxyl, hydroxyl, and thiol functionalities were introduced on chitosan-coated magnetic probe via simple reactions with small reactive organic molecules to afford a series of biofunctionalized nanoparticles. Physico-chemical characterizations of these functionalized nanoparticles were performed by TEM, XRD, DLS, FTIR, and VSM. The colloidal stability of these functionalized iron oxide nanoparticles was investigated in presence of phosphate buffer saline, high salt concentrations and different cell media for 1 week. MRI analysis of human cervical carcinoma (HeLa) cell lines treated with nanoparticles elucidated that the amine-functionalized nanoparticles exhibited higher amount of signal darkening and lower T 2 relaxation in comparison to the others. The cellular internalization efficacy of these functionalized SPIONs was also investigated with HeLa cancer cell line by magnetically activated cell sorting (MACS) and fluorescence microscopy and results established selectively higher internalization efficacy of amine-functionalized nanoparticles to cancer cells. These positive attributes demonstrated that these nanoconjugates can be used as a promising platform for further in vitro and in vivo biological evaluations.

  19. Quantification of Superparamagnetic Iron Oxide (SPIO)-labeled Cells Using MRI

    Science.gov (United States)

    Rad, Ali M; Arbab, Ali S; Iskander, ASM; Jiang, Quan; Soltanian-Zadeh, Hamid

    2015-01-01

    Purpose To show the feasibility of using magnetic resonance imaging (MRI) to quantify superparamagnetic iron oxide (SPIO)-labeled cells. Materials and Methods Lymphocytes and 9L rat gliosarcoma cells were labeled with Ferumoxides-Protamine Sulfate complex (FE-PRO). Cells were labeled efficiently (more than 95%) and iron concentration inside each cell was measured by spectrophotometry (4.77-30.21 picograms). Phantom tubes containing different number of labeled or unlabeled cells as well as different concentrations of FE-PRO were made. In addition, labeled and unlabeled cells were injected into fresh and fixed rat brains. Results Cellular viability and proliferation of labeled and unlabeled cells were shown to be similar. T2-weighted images were acquired using 7 T and 3 T MRI systems and R2 maps of the tubes containing cells, free FE-PRO, and brains were made. There was a strong linear correlation between R2 values and labeled cell numbers but the regression lines were different for the lymphocytes and gliosarcoma cells. Similarly, there was strong correlation between R2 values and free iron. However, free iron had higher R2 values than the labeled cells for the same concentration of iron. Conclusion Our data indicated that in vivo quantification of labeled cells can be done by careful consideration of different factors and specific control groups. PMID:17623892

  20. Hydrogen Treatment for Superparamagnetic VO2 Nanowires with Large Room-Temperature Magnetoresistance.

    Science.gov (United States)

    Li, Zejun; Guo, Yuqiao; Hu, Zhenpeng; Su, Jihu; Zhao, Jiyin; Wu, Junchi; Wu, Jiajing; Zhao, Yingcheng; Wu, Changzheng; Xie, Yi

    2016-07-04

    One-dimensional (1D) transition metal oxide (TMO) nanostructures are actively pursued in spintronic devices owing to their nontrivial d electron magnetism and confined electron transport pathways. However, for TMOs, the realization of 1D structures with long-range magnetic order to achieve a sensitive magnetoelectric response near room temperature has been a longstanding challenge. Herein, we exploit a chemical hydric effect to regulate the spin structure of 1D V-V atomic chains in monoclinic VO2 nanowires. Hydrogen treatment introduced V(3+) (3d(2) ) ions into the 1D zigzag V-V chains, triggering the formation of ferromagnetically coupled V(3+) -V(4+) dimers to produce 1D superparamagnetic chains and achieve large room-temperature negative magnetoresistance (-23.9 %, 300 K, 0.5 T). This approach offers new opportunities to regulate the spin structure of 1D nanostructures to control the intrinsic magnetoelectric properties of spintronic materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Harmonic decomposition of magneto-optical signal from superparamagnetic Fe3O4 nanoparticles

    Science.gov (United States)

    Syed, Maarij; Patterson, Cody; Takemura, Yasushi

    Superparamagnetic nanoparticles (SPNPs) are expected to play an increasingly important role in bio-imaging and therapy. These applications rely on understanding SPNPs magnetic properties which have been successfully characterized by AC Faraday rotation (FR). AC FR is used here to build on results presented earlier by measuring solutions of surfactant-coated magnetite nanoparticles. The setup employs a He-Ne laser, polarizing components, a sinusoidal B-field, and a lock-in detection scheme to measure the SPNPs FR. Such a setup provides a novel, economical way of determining important magnetic properties of SPNPs. The main intensity signal (1f) along with higher harmonics are collected and analyzed to calculate quantities such as the Verdet constant and the magnetic moment. We hope further analysis can also reveal details of size distribution and relaxation times of SPNPs. We will present results from samples with various concentrations as well as a particular concentration subjected to a range of B-field frequencies (between 800 Hz and 14 kHz). Findings are compared to results from more traditional techniques like magnetic susceptibility measurements, magnetic force microscopy, etc. We will also address the comparative advantages of this technique and its limitations.

  2. Evolution of magnetism by rolling up hexagonal boron nitride nanosheets tailored with superparamagnetic nanoparticles.

    Science.gov (United States)

    Hwang, Da Young; Choi, Kyoung Hwan; Park, Jeong Eon; Suh, Dong Hack

    2017-02-01

    Controlling tunable properties by rolling up two dimensional nanomaterials is an exciting avenue for tailoring the electronic and magnetic properties of materials at the nanoscale. We demonstrate the tailoring of a magnetic nanocomposite through hybridization with magnetic nanomaterials using hexagonal boron nitride (h-BN) templates as an effective way to evolve magnetism for the first time. Boron nitride nanosheets exhibited their typical diamagnetism, but rolled-up boron nitride sheets (called nanoscrolls) clearly have para-magnetism in the case of magnetic susceptibility. Additionally, the Fe 3 O 4 NP sample shows a maximum ZFC curve at about 103 K, which indicates well dispersed superparamagnetic nanoparticles. The ZFC curve for the h-BN-Fe 3 O 4 NP scrolls exhibited an apparent rounded maximum blocking temperature at 192 K compared to the Fe 3 O 4 NPs, leading to a dramatic increase in T B . These magnetic nanoscroll derivatives are remarkable materials and should be suitable for high-performance composites and nano-, medical- and electromechanical-devices.

  3. Fluorescent labelling of DNA on superparamagnetic nanoparticles by a perylene bisimide derivative for cell imaging

    Energy Technology Data Exchange (ETDEWEB)

    Maltas, Esra, E-mail: maltasesra@gmail.com [Selcuk University, Faculty of Science, Department of Chemistry, 42075 Konya (Turkey); Malkondu, Sait [Selcuk University, Faculty of Science, Department of Chemistry, 42075 Konya (Turkey); Uyar, Pembegul [Selcuk University, Faculty of Science, Department of Biology, 42075 Konya (Turkey); Selcuk University, Advanced Technology Research and Application Center, Konya (Turkey); Ozmen, Mustafa [Selcuk University, Faculty of Science, Department of Chemistry, 42075 Konya (Turkey)

    2015-03-01

    N,N′-Bis[tris-(2-aminoethyl) amine]-3,4,9,10-perylenetetracarboxylic diimide (PBI-TRIS), nonfluorescent dye was used to fluorescent labelling of DNA. For this aim, (3-aminopropyl) triethoxysilane (APTS) modified superparamagnetic iron oxide nanoparticles (SPIONs) were synthesized to provide a suitable surface for binding of DNA. Amine functionalized nanoparticles showed a high immobilization capacity (82.70%) at 25 mg of nanoparticle concentration for Calf thymus DNA. Binding capacity of PBI-TRIS to DNA-SPION was also found as 1.93 μM on 25 mg of nanoparticles by using UV–vis spectroscopy. Binding of PBI-TRIS to DNA onto nanoparticles was also characterized by scanning electron microscopy and infrared spectroscopy. The confocal images of PBI-TRIS labelled DNA-SPION and breast cells were taken at 488 and 561.7 nm of excitation wavelengths. Cell image was also compared with a commercial dye, DAPI at 403.7 nm of excitation wavelength. Results showed that PBI-TRIS can be used for cell staining. - Highlights: • Functionalized SPIONs were synthesized and treated with DNA. • The binding of PBI-TRIS with DNA was studied. • The image of PBI-TRIS labelled DNA-SPION was detected by a confocal microscope.

  4. Fluorescent labelling of DNA on superparamagnetic nanoparticles by a perylene bisimide derivative for cell imaging

    International Nuclear Information System (INIS)

    Maltas, Esra; Malkondu, Sait; Uyar, Pembegul; Ozmen, Mustafa

    2015-01-01

    N,N′-Bis[tris-(2-aminoethyl) amine]-3,4,9,10-perylenetetracarboxylic diimide (PBI-TRIS), nonfluorescent dye was used to fluorescent labelling of DNA. For this aim, (3-aminopropyl) triethoxysilane (APTS) modified superparamagnetic iron oxide nanoparticles (SPIONs) were synthesized to provide a suitable surface for binding of DNA. Amine functionalized nanoparticles showed a high immobilization capacity (82.70%) at 25 mg of nanoparticle concentration for Calf thymus DNA. Binding capacity of PBI-TRIS to DNA-SPION was also found as 1.93 μM on 25 mg of nanoparticles by using UV–vis spectroscopy. Binding of PBI-TRIS to DNA onto nanoparticles was also characterized by scanning electron microscopy and infrared spectroscopy. The confocal images of PBI-TRIS labelled DNA-SPION and breast cells were taken at 488 and 561.7 nm of excitation wavelengths. Cell image was also compared with a commercial dye, DAPI at 403.7 nm of excitation wavelength. Results showed that PBI-TRIS can be used for cell staining. - Highlights: • Functionalized SPIONs were synthesized and treated with DNA. • The binding of PBI-TRIS with DNA was studied. • The image of PBI-TRIS labelled DNA-SPION was detected by a confocal microscope

  5. Magnetic separation of encapsulated islet cells labeled with superparamagnetic iron oxide nano particles.

    Science.gov (United States)

    Mettler, Esther; Trenkler, Anja; Feilen, Peter J; Wiegand, Frederik; Fottner, Christian; Ehrhart, Friederike; Zimmermann, Heiko; Hwang, Yong Hwa; Lee, Dong Yun; Fischer, Stefan; Schreiber, Laura M; Weber, Matthias M

    2013-01-01

    Islet cell transplantation is a promising option for the restoration of normal glucose homeostasis in patients with type 1 diabetes. Because graft volume is a crucial issue in islet transplantations for patients with diabetes, we evaluated a new method for increasing functional tissue yield in xenogeneic grafts of encapsulated islets. Islets were labeled with three different superparamagnetic iron oxide nano particles (SPIONs; dextran-coated SPION, siloxane-coated SPION, and heparin-coated SPION). Magnetic separation was performed to separate encapsulated islets from the empty capsules, and cell viability and function were tested. Islets labeled with 1000 μg Fe/ml dextran-coated SPIONs experienced a 69.9% reduction in graft volume, with a 33.2% loss of islet-containing capsules. Islets labeled with 100 μg Fe/ml heparin-coated SPIONs showed a 46.4% reduction in graft volume, with a 4.5% loss of capsules containing islets. No purification could be achieved using siloxane-coated SPIONs due to its toxicity to the primary islets. SPION labeling of islets is useful for transplant purification during islet separation as well as in vivo imaging after transplantation. Furthermore, purification of encapsulated islets can also reduce the volume of the encapsulated islets without impairing their function by removing empty capsules. © 2013 John Wiley & Sons A/S.

  6. Self-assembled superparamagnetic nanoparticles as MRI contrast agents— A review

    International Nuclear Information System (INIS)

    Su Hong-Ying; Wu Chang-Qiang; Ai Hua; Li Dan-Yang

    2015-01-01

    Recent progress of the preparation and applications of superparamagnetic iron oxide (SPIO) clusters as magnetic resonance imaging (MRI) probes is reviewed with regard to their applications in labeling and tracking cells in vivo, in diagnosis of cardiovascular diseases and tumors, and in drug delivery systems. Magnetic nanoparticles (NPs), especially SPIO nanoparticles, have long been used as MRI contrast agents and as an advantageous nanoplatform for drug delivery, taking advantage of their unique magnetic properties and ability to function at the molecular and cellular levels. Due to advances in nanotechnology, various means to control SPIO NPs’ size, composition, magnetization and relaxivity have been developed, as well as ways to usefully modify their surface. Recently, self-assembly of SPIO NP clusters in particulate carriers—such as polymeric micelles, vesicles, liposomes, and layer-by-layer (LbL) capsules—have been widely studied for application as ultrasensitive MRI probes, owing to their remarkably high spin–spin (T 2 ) relaxivity and convenience for further functionalization. (topical review)

  7. Synthesis and characterization of superparamagnetic iron oxide nanoparticles as calcium-responsive MRI contrast agents

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Pengfei [State Key Laboratory Breeding Base of Nonferrous Metals and Specific Materials Processing, School of Materials Science and Engineering, Guilin University of Technology, Jian Gan Road 12, Guilin 541004 (China); Shen, Zhiwei [Second Affiliated Hospital of Shantou University Medical College, Dong Xia North Road, Shantou 515041,China (China); Zhang, Baolin, E-mail: baolinzhang@ymail.com [State Key Laboratory Breeding Base of Nonferrous Metals and Specific Materials Processing, School of Materials Science and Engineering, Guilin University of Technology, Jian Gan Road 12, Guilin 541004 (China); Wang, Jun [State Key Laboratory Breeding Base of Nonferrous Metals and Specific Materials Processing, School of Materials Science and Engineering, Guilin University of Technology, Jian Gan Road 12, Guilin 541004 (China); Wu, Renhua, E-mail: rhwu@stu.edu.cn [Second Affiliated Hospital of Shantou University Medical College, Dong Xia North Road, Shantou 515041,China (China)

    2016-12-15

    Highlights: • SPIONs were conjugated with EGTA by EDC/sulfo-NHS method. • The presence of Ca{sup 2+} induced the aggregation of EGTA-SPIONs. • The aggregation of EGTA-SPIONs increased the T2 relaxation time. • EGTA-SPIONs can be used for the calcium imaging with MRI. - Abstract: Superparamagnetic iron oxide nanoparticles (SPIONs) as T2 contrast agents have great potential to sense calcium ion (Ca{sup 2+}) using magnetic resonance imaging (MRI). Here we prepared calcium-responsive SPIONs for MRI, formed by combining poly(ethylene glycol) (PEG) and polyethylenimine (PEI) coated iron oxide nanoparticle (PEI/PEG-SPIONs) contrast agents with the straightforward calcium-sensing compound EGTA (ethylene glycol tetraacetic acid). EGTA was conjugated onto PEI/PEG-SPIONs using EDC/sulfo-NHS method. EGTA-SPIONs were characterized using TEM, XPS, DSL, TGA and SQUIID. DSL results show that the SPIONs aggregate in the presence of Ca{sup 2+}. MRI analyses indicate that the water proton T2 relaxation rates in HEPES suspensions of the EGTA-SPIONs significantly increase with the calcium concentration because the SPIONs aggregate in the presence of Ca{sup 2+}. The T2 values decreased 25% when Ca{sup 2+} concentration decreased from 1.2 to 0.8 mM. The aggregation of EGTA-SPIONs could be reversed by EDTA. EGTA-SPIONs have potential as smart contrast agents for Ca{sup 2+}-sensitive MRI.

  8. Superparamagnetic nickel colloidal nanocrystal clusters with antibacterial activity and bacteria binding ability

    Science.gov (United States)

    Peng, Bo; Zhang, Xinglin; Aarts, Dirk G. A. L.; Dullens, Roel P. A.

    2018-06-01

    Recent progress in synthetic nanotechnology and the ancient use of metals in food preservation and the antibacterial treatment of wounds have prompted the development of nanometallic materials for antimicrobial applications1-4. However, the materials designed so far do not simultaneously display antimicrobial activity and the capability of binding and capturing bacteria and spores. Here, we develop a one-step pyrolysis procedure to synthesize monodisperse superparamagnetic nickel colloidal nanocrystal clusters (SNCNCs), which show both antibacterial activity and the ability to bind Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria, as well as bacterial spores. The SNCNCs are formed from a rapid burst of nickel nanoparticles, which self-assemble slowly into clusters. The clusters can magnetically extract 99.99% of bacteria and spores and provide a promising approach for the removal of microbes, including hard-to-treat microorganisms. We believe that our work illustrates the exciting opportunities that nanotechnology offers for alternative antimicrobial strategies and other applications in microbiology.

  9. Analysis of surface properties of fixed and live cells using derivatized agarose beads.

    Science.gov (United States)

    Navarro, Vanessa M; Walker, Sherri L; Badali, Oliver; Abundis, Maria I; Ngo, Lylla L; Weerasinghe, Gayani; Barajas, Marcela; Zem, Gregory; Oppenheimer, Steven B

    2002-01-01

    A novel assay has been developed for the histochemical characterization of surface properties of cells based on their adhesion to agarose beads derivatized with more than 100 types of molecules, including sugars, lectins and other proteins, and amino acids. The assay simply involves mixing small quantities of washed cells and beads in droplets on glass microscope slides and determining to which beads various cell types adhere. Distilled water was found to be the best medium for this assay because added ions or molecules in other media inhibit adhesion in some cases. Many cells, however, cannot tolerate distilled water. Here we show that cells fixed with either of two fixatives (1% formaldehyde or Prefer fixative) displayed similar bead-binding properties as did live cells. Specificity of cell-bead binding was tested by including specific free molecules in the test suspensions in hapten-type inhibition experiments. If a hapten compound inhibited live-cell adhesion to a specific bead, it also inhibited fixed-cell adhesion to a specific bead. The results of these experiments suggest that fixed cells display authentic surface properties, opening the door for the use of this assay with many cell types that cannot tolerate distilled water.

  10. Formation of beads-on-a-string structures during the pinch-off of viscoelastic filaments

    Science.gov (United States)

    Bhat, Pradeep; Appathurai, Santosh; Harris, Michael; Pasquali, Matteo; McKinley, Gareth; Basaran, Osman

    2009-11-01

    Breakup of liquid filaments is omnipresent in nature and technology. When a filament formed by placing a drop of syrup between a thumb and a forefinger is stretched by pulling apart the two fingers, it resembles a thinning cylinder. If the same experiment is repeated with saliva, the filament's morphology close to pinch-off resembles that of beads of several sizes interconnected by slender threads. Although there is general agreement that formation of such beads-on-a-string (BOAS) morphology only occurs for viscoelastic fluids, the mechanism behind this phenomenon remains unclear and controversial. The physics of formation of BOAS structures is probed here by simulation which reveals that viscoelasticity alone does not give rise to a small, satellite bead between two much larger main drops (beads) but that inertia is required for its formation. Viscoelasticity, however, enhances the growth of the satellite bead and delays pinch-off, which leads to a relatively long-lived, stable beaded filament. The new simulations also show the formation of second-generation sub-satellite beads in certain cases, as observed experimentally but not, heretofore, predicted theoretically.

  11. Formation of beads-on-a-string structures during break-up of viscoelastic filaments

    Science.gov (United States)

    Bhat, Pradeep P.; Appathurai, Santosh; Harris, Michael T.; Pasquali, Matteo; McKinley, Gareth H.; Basaran, Osman A.

    2010-08-01

    Break-up of viscoelastic filaments is pervasive in both nature and technology. If a filament is formed by placing a drop of saliva between a thumb and forefinger and is stretched, the filament's morphology close to break-up corresponds to beads of several sizes interconnected by slender threads. Although there is general agreement that formation of such beads-on-a-string (BOAS) structures occurs only for viscoelastic fluids, the underlying physics remains unclear and controversial. The physics leading to the formation of BOAS structures is probed by numerical simulation. Computations reveal that viscoelasticity alone does not give rise to a small, satellite bead between two much larger main beads but that inertia is required for its formation. Viscoelasticity, however, enhances the growth of the bead and delays pinch-off, which leads to a relatively long-lived beaded structure. We also show for the first time theoretically that yet smaller, sub-satellite beads can also form as seen in experiments.

  12. Development of alginate gel beads with a potential use in the treatment against acute lead poisoning.

    Science.gov (United States)

    Tahtat, Djamel; Bouaicha, Malika Nawel; Benamer, Samah; Nacer-Khodja, Assia; Mahlous, Mohamed

    2017-12-01

    The objective was to develop alginate beads that could adsorb lead ions in gastric pH, in view to preconize their use in gastric lavage following lead poisoning. The swelling measurements of both, dry and hydrated beads, were carried out in simulated gastric fluid (SGF). The sorption kinetics was examined at lead concentrations ranging from 50 to 200mg/l. Calcium released during the sorption process was investigated. The swelling rate of the dry beads increased considerably with time increase and reached the equilibrium at 736% after 240min; concerning the hydrated beads, the equilibrium swelling reached 139% after 180min. The adsorption of Pb (II) in SGF by dry beads increased with the increase of time and initial lead concentration. The adsorption kinetics of Pb ions by hydrated alginate beads indicated a rapid binding of Pb ions to the sorbent during the first 15min for all the concentrations, followed by a slow increase until the equilibrium was reached after 90min. The adsorption capacity of Pb ions increased with the increase of the storage time in water at 4°C and with the weight. The amount of Ca 2+ released by the beads increased with the increase of Pb ions a rate. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Chemical and toxicological assessment of arsenic sorption onto Fe-sericite composite powder and beads.

    Science.gov (United States)

    Kim, Jiwon; Lee, Cheongho; Lee, Seung Mok; Lalhmunsiama; Jung, Jinho

    2018-01-01

    Batch sorption and leaching of arsenic (1-30mgL -1 ) on Fe-sericite composite powder and beads were investigated in this study. Fe-sericite composite powder was made from natural sericite modified with iron, and alginate was used to transform the powder into beads. The maximum sorption capacities of the Fe-sericite composite powder (15.04 and 13.21mgg -1 for As(III) and As(V), respectively) were higher than those of the corresponding beads (9.02 and 7.11mgg -1 for As(III) and As(V), respectively) owing to the higher specific surface area of the powder. In addition, the leaching amounts of As(III) from Fe-sericite composite beads (≤ 15.03%) were higher than those of the corresponding powder (≤ 5.71%). However, acute toxicity of As(III)-sorbed Fe-sericite composite beads toward Daphnia magna was not significantly different from that of the corresponding powder (p > 0.05). Considering higher uptake of the powder particles by the daphnids, Fe-sericite composite beads seem to be a more appropriate and safer sorbent for arsenic removal in practical application. Based on Fe content, Fe-sericite composite beads had similar or higher maximum sorption capacities (71.19 and 56.11mgg -1 Fe for As(III) and As(V), respectively) than those of previously reported sorbents. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Preparation of Silk Sericin/Lignin Blend Beads for the Removal of Hexavalent Chromium Ions

    Science.gov (United States)

    Kwak, Hyo Won; Shin, Munju; Yun, Haesung; Lee, Ki Hoon

    2016-01-01

    In the present study, novel adsorbents having high adsorption capability and reusability were prepared using agricultural by-products: silk sericin and lignin. Silk sericin and lignin blend beads were successfully prepared using simple coagulation methods for the removal of hexavalent chromium (Cr(VI)) from aqueous solution. A 1 M lithium chloride (LiCl)/dimethyl sulfoxide (DMSO) solvent system successfully dissolved both sericin and lignin and had sufficient viscosity for bead preparation. Compared to the conventional sericin bead adsorbent, sericin/lignin blend beads showed higher Cr(VI) adsorption capacity. The amount of lignin added to the adsorbent greatly affected the adsorption capacity of the beads, and a 50:50 sericin/lignin blend ratio was optimal. Adsorption behavior followed the Freundlich isotherm, which means the adsorption of Cr(VI) occurred on the heterogeneous surface. Cr(VI) adsorption capability increased with temperature because of thermodynamic-kinetic effects. In addition, over 90% of Cr(VI) ions were recovered from the Cr(VI) adsorbed sericin/lignin beads in a 1 M NaOH solution. The adsorption-desorption recycling process was stable for more than seven cycles, and the recycling efficiency was 82%. It is expected that the sericin/lignin beads could be successfully applied in wastewater remediation especially for hazardous Cr(VI) ions in industrial wastewater. PMID:27598142

  15. Wax-incorporated emulsion gel beads of calcium pectinate for intragastric floating drug delivery.

    Science.gov (United States)

    Sriamornsak, Pornsak; Asavapichayont, Panida; Nunthanid, Jurairat; Luangtana-Anan, Manee; Limmatvapirat, Sontaya; Piriyaprasarth, Suchada

    2008-01-01

    The purpose of this study was to prepare wax-incorporated pectin-based emulsion gel beads using a modified emulsion-gelation method. The waxes in pectin-olive oil mixtures containing a model drug, metronidazole, were hot-melted, homogenized and then extruded into calcium chloride solution. The beads formed were separated, washed with distilled water and dried for 12 h. The influence of various types and amounts of wax on floating and drug release behavior of emulsion gel beads of calcium pectinate was investigated. The drug-loaded gel beads were found to float on simulated gastric fluid if the sufficient amount of oil was used. Incorporation of wax into the emulsion gel beads affected the drug release. Water-soluble wax (i.e. polyethylene glycol) increased the drug release while other water-insoluble waxes (i.e. glyceryl monostearate, stearyl alcohol, carnauba wax, spermaceti wax and white wax) significantly retarded the drug release. Different waxes had a slight effect on the drug release. However, the increased amount of incorporated wax in the formulations significantly sustained the drug release while the beads remained floating. The results suggest that wax-incorporated emulsion gel beads could be used as a carrier for intragastric floating drug delivery.

  16. REVIEW: CHITOSAN BASED HYDROGEL POLYMERIC BEADS – AS DRUG DELIVERY SYSTEM

    Directory of Open Access Journals (Sweden)

    Manjusha Rani

    2010-11-01

    Full Text Available Chitosan obtained by alkaline deacetylation of chitin is a non-toxic, biocompatible, and biodegradable natural polymer. Chitosan-based hydrogel polymeric beads have been extensively studied as micro- or nano-particulate carriers in the pharmaceutical and medical fields, where they have shown promise for drug delivery as a result of their controlled and sustained release properties, as well as biocompatibility with tissue and cells. To introduce desired properties and enlarge the scope of the potential applications of chitosan, graft copolymerization with natural or synthetic polymers on it has been carried out, and also, various chitosan derivatives have been utilized to form beads. The desired kinetics, duration, and rate of drug release up to therapeutical level from polymeric beads are limited by specific conditions such as beads material and their composition, bead preparation method, amount of drug loading, drug solubility, and drug polymer interaction. The present review summarizes most of the available reports about compositional and structural effects of chitosan-based hydrogel polymeric beads on swelling, drug loading, and releasing properties. From the studies reviewed it is concluded that chitosan-based hydrogel polymeric beads are promising drug delivery systems.

  17. Preparation of Silk Sericin/Lignin Blend Beads for the Removal of Hexavalent Chromium Ions

    Directory of Open Access Journals (Sweden)

    Hyo Won Kwak

    2016-09-01

    Full Text Available In the present study, novel adsorbents having high adsorption capability and reusability were prepared using agricultural by-products: silk sericin and lignin. Silk sericin and lignin blend beads were successfully prepared using simple coagulation methods for the removal of hexavalent chromium (Cr(VI from aqueous solution. A 1 M lithium chloride (LiCl/dimethyl sulfoxide (DMSO solvent system successfully dissolved both sericin and lignin and had sufficient viscosity for bead preparation. Compared to the conventional sericin bead adsorbent, sericin/lignin blend beads showed higher Cr(VI adsorption capacity. The amount of lignin added to the adsorbent greatly affected the adsorption capacity of the beads, and a 50:50 sericin/lignin blend ratio was optimal. Adsorption behavior followed the Freundlich isotherm, which means the adsorption of Cr(VI occurred on the heterogeneous surface. Cr(VI adsorption capability increased with temperature because of thermodynamic-kinetic effects. In addition, over 90% of Cr(VI ions were recovered from the Cr(VI adsorbed sericin/lignin beads in a 1 M NaOH solution. The adsorption-desorption recycling process was stable for more than seven cycles, and the recycling efficiency was 82%. It is expected that the sericin/lignin beads could be successfully applied in wastewater remediation especially for hazardous Cr(VI ions in industrial wastewater.

  18. Sodium bicarbonate-gelled chitosan beads as mechanically stable carriers for the covalent immobilization of enzymes.

    Science.gov (United States)

    Wahba, Marwa I

    2018-03-01

    The poor mechanical stability of chitosan has long impeded its industrial utilization as an immobilization carrier. In this study, the mechanical properties of chitosan beads were greatly improved through utilizing the slow rate of the sodium bicarbonate-induced chitosan gelation and combining it with the chemical cross-linking action of glutaraldehyde (GA). The GA-treated sodium bicarbonate-gelled chitosan beads exhibited much better mechanical properties and up to 2.45-fold higher observed activity of the immobilized enzyme (β-D-galactosidase (β-gal)) when compared to the GA-treated sodium tripolyphosphate (TPP)-gelled chitosan beads. The differences between the sodium bicarbonate-gelled and the TPP-gelled chitosan beads were proven visually and also via scanning electron microscopy, elemental analysis, and differential scanning calorimetry. Moreover, the optimum pH, the optimum temperature, the apparent K m , and the apparent V max of the β-gals immobilized onto the two aforementioned types of chitosan beads were determined and compared. A reusability study was also performed. This study proved the superiority of the sodium bicarbonate-gelled chitosan beads as they retained 72.22 ± 4.57% of their initial observed activity during the 13 th reusability cycle whereas the TPP-gelled beads lost their activity during the first four reusability cycles, owing to their fragmentation. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:347-361, 2018. © 2017 American Institute of Chemical Engineers.

  19. Decolourisation of dyes under electro-Fenton process using Fe alginate gel beads

    Energy Technology Data Exchange (ETDEWEB)

    Rosales, E.; Iglesias, O.; Pazos, M. [Department of Chemical Engineering, University of Vigo, Isaac Newton Building, Campus As Lagoas, Marcosende 36310, Vigo (Spain); Sanroman, M.A., E-mail: sanroman@uvigo.es [Department of Chemical Engineering, University of Vigo, Isaac Newton Building, Campus As Lagoas, Marcosende 36310, Vigo (Spain)

    2012-04-30

    Highlights: Black-Right-Pointing-Pointer Catalytic activity of Fe alginate gel beads for the remediation of wastewater was tested. Black-Right-Pointing-Pointer New electro-Fenton process for the remediation of polluted wastewater. Black-Right-Pointing-Pointer Continuous dye treatment without operational problem with high removal. - Abstract: This study focuses on the application of electro-Fenton technique by use of catalytic activity of Fe alginate gel beads for the remediation of wastewater contaminated with synthetic dyes. The Fe alginate gel beads were evaluated for decolourisation of two typical dyes, Lissamine Green B and Azure B under electro-Fenton process. After characterization of Fe alginate gel beads, the pH effect on the process with Fe alginate beads and a comparative study of the electro-Fenton process with free Fe and Fe alginate bead was done. The results showed that the use of Fe alginate beads increases the efficiency of the process; moreover the developed particles show a physical integrity in a wide range of pH (2-8). Around 98-100% of dye decolourisation was obtained for both dyes by electro-Fenton process in successive batches. Therefore, the process was performed with Fe alginate beads in a bubble continuous reactor. High color removal (87-98%) was attained for both dyes operating at a residence time of 30 min, without operational problems and maintaining particle shapes throughout the oxidation process. Consequently, the stable performance of Fe alginate beads opens promising perspectives for fast and economical treatment of wastewater polluted by dyes or similar organic contaminants.

  20. Development of a novel colorimetric sensor based on alginate beads for monitoring rainbow trout spoilage.

    Science.gov (United States)

    Majdinasab, Marjan; Hosseini, Seyed Mohammad Hashem; Sepidname, Marziyeh; Negahdarifar, Manizheh; Li, Peiwu

    2018-05-01

    Alginate is a non-toxic, renewable, and linear copolymer obtained from the brown algae Laminaria digitata that can be easily shaped into beads. Its good gel forming properties have made it useful for entrapping food and pharmaceutical ingredients. In this study, alginate beads were used in a novel application as a colorimetric sensor in food intelligent packaging. Colorimetric sensor was developed through entrapping red cabbage extract as a pH indicator in alginate beads. The pH indicator beads were used in rainbow trout packaging for monitoring fillets spoilage. Color change of beads during fish storage was measured using the CIELab method. The alginate bead colorimetric sensor is validated by measuring total volatile basic nitrogen (TVB-N) levels and microbial populations in fish samples. Moreover, peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) were evaluated during storage. Results indicated that increasing the bacterial population during storage and production of proteolytic enzymes resulted in protein degradation, accumulation of volatile amine compounds, increase in the pH and finally color change of alginate beads. The values of TVB-N, pH, PV and TBARS increased with time of storage. The results of TVB-N and microbial growth were in accordance with color change of beads and CIELab data. Therefore, the proposed system enjoys a high sensitivity to pH variations and is capable of monitoring the spoilage of fish or other protein-rich products through its wide range of color changes. The alginate beads containing the red cabbage extract can, thus, be used as a low-cost colorimetric sensor for intelligent packaging applications.

  1. Decolourisation of dyes under electro-Fenton process using Fe alginate gel beads

    International Nuclear Information System (INIS)

    Rosales, E.; Iglesias, O.; Pazos, M.; Sanromán, M.A.

    2012-01-01

    Highlights: ► Catalytic activity of Fe alginate gel beads for the remediation of wastewater was tested. ► New electro-Fenton process for the remediation of polluted wastewater. ► Continuous dye treatment without operational problem with high removal. - Abstract: This study focuses on the application of electro-Fenton technique by use of catalytic activity of Fe alginate gel beads for the remediation of wastewater contaminated with synthetic dyes. The Fe alginate gel beads were evaluated for decolourisation of two typical dyes, Lissamine Green B and Azure B under electro-Fenton process. After characterization of Fe alginate gel beads, the pH effect on the process with Fe alginate beads and a comparative study of the electro-Fenton process with free Fe and Fe alginate bead was done. The results showed that the use of Fe alginate beads increases the efficiency of the process; moreover the developed particles show a physical integrity in a wide range of pH (2–8). Around 98–100% of dye decolourisation was obtained for both dyes by electro-Fenton process in successive batches. Therefore, the process was performed with Fe alginate beads in a bubble continuous reactor. High color removal (87–98%) was attained for both dyes operating at a residence time of 30 min, without operational problems and maintaining particle shapes throughout the oxidation process. Consequently, the stable performance of Fe alginate beads opens promising perspectives for fast and economical treatment of wastewater polluted by dyes or similar organic contaminants.

  2. Note: A quartz cell with Pt single crystal bead electrode for electrochemical scanning tunneling microscope measurements.

    Science.gov (United States)

    Xia, Zhigang; Wang, Jihao; Hou, Yubin; Lu, Qingyou

    2014-09-01

    In this paper, we provide and demonstrate a design of a unique cell with Pt single crystal bead electrode for electrochemical scanning tunneling microscope (ECSTM) measurements. The active metal Pt electrode can be protected from air contamination during the preparation process. The transparency of the cell allows the tip and bead to be aligned by direct observation. Based on this, a new and effective alignment method is introduced. The high-quality bead preparations through this new cell have been confirmed by the ECSTM images of Pt (111).

  3. Magnetic composite beads for sorption of cesium ions from aqueous streams

    International Nuclear Information System (INIS)

    Shinde, Rakesh N.; Pandey, A.K.; Acharya, R.; Rajurkar, N.S.

    2014-01-01

    Magnetic separation of metal ions is one of the promising methods due to simple, fast, efficient and cost effective technology. Highly selective magnetic sorbents can be designed by immobilizing functional groups in magnetic carrier which binds to the target specific ions. In the present work chitosan-(3-aminopropyl) triethoxysilane (APTS)- copperferrocyanide (CFC) composite beads have been synthesized for sorption of 137 Cs ions from aqueous streams. Physical characterization of the best resulted polymer beads was carried out by SEM-EDX and VSM technique. Sorption of Cs ions in the various magnetic polymer beads were studied in different aqueous condition by 137 Cs (662 KeV) radiotracer assay

  4. On-chip magnetic bead-based DNA melting curve analysis using a magnetoresistive sensor

    DEFF Research Database (Denmark)

    Rizzi, Giovanni; Østerberg, Frederik Westergaard; Henriksen, Anders Dahl

    2014-01-01

    We present real-time measurements of DNA melting curves in a chip-based system that detects the amount of surface-bound magnetic beads using magnetoresistive magnetic field sensors. The sensors detect the difference between the amount of beads bound to the top and bottom sensor branches....... The beads are magnetized by the field arising from the bias current passed through the sensors. We demonstrate the first on-chip measurements of the melting of DNA hybrids upon a ramping of the temperature. This overcomes the limitation of using a single washing condition at constant temperature. Moreover...

  5. Sequential mass spectrometric analysis of uranium and plutonium employing resin bead technique

    International Nuclear Information System (INIS)

    Ramakumar, K.L.; Aggarwal, S.K.; Chitambar, S.A.; Jain, H.C.

    1985-01-01

    Sequential mass spectrometric analysis of uranium and plutonium employing anion exchange resin bead technique is reported using a high sensitive single stage magnetic analyser instrument, the routinely employed rhenium double filament assembly and 0.5M HNO 3 as a wetting agent for loading the resin beads. A precision of bettter than 0.3per cent (2sigma) is obtained on the isotopic ratio measurements. However, extreme care has to be exercised to carry the resin bead experiments under ultra clean conditions so as to avoid pick up of contamination. (author)

  6. Effect of welding current and speed on occurrence of humping bead in high-speed GMAW

    Institute of Scientific and Technical Information of China (English)

    Chen Ji; Wu Chuansong

    2009-01-01

    The developed mathematical model of humping formation mechanism in high-speed gas metal arc welding (GMAW) is used to analyze the effects of welding current and welding speed on the occurrence of humping bead. It considers both the momentum and heat content of backward flowing molten jet inside weld pool. Three-dimensional geometry of weld pool, the spacing between two adjacent humps and hump height along humping weld bead are calculated under different levels of welding current and welding speed. It shows that wire feeding rate, power intensity and the moment of backward flowing molten jet are the major factors on humping bead formation.

  7. Silica-supported Macroporous Chitosan Bead for Affinity Purification of Trypsin Inhibitor

    Institute of Scientific and Technical Information of China (English)

    Feng Na XI; Jian Min WU; Ming Ming LUAN

    2005-01-01

    Macroporous cross-linking chitosan layer coated on silica gel (CTS-SiO2) was prepared by phase inversion and polyethylene glycol (PEG) molecular imprinting methods. Formation of macroporous surface was investigated by scanning electron microscopy (SEM) and BET analysis.The prepared bead was activated by reacting with 1,2-ethylene diglycidyl ether for introducing epoxy groups, and trypsin could be efficiently immobilized on the bead as a biospecific ligand.The bead bearing trypsin was employed to purify trypsin inhibitor (TIs) from egg white as affinity adsorbent.

  8. Efficient MRI labeling of endothelial progenitor cells: design of thiolated surface stabilized superparamagnetic iron oxide nanoparticles.

    Science.gov (United States)

    Shahnaz, Gul; Kremser, Christian; Reinisch, Andreas; Vetter, Anja; Laffleur, Flavia; Rahmat, Deni; Iqbal, Javed; Dünnhaupt, Sarah; Salvenmoser, Willi; Tessadri, Richard; Griesser, Ulrich; Bernkop-Schnürch, Andreas

    2013-11-01

    The aim of this study was to design thiolated surface stabilized superparamagnetic iron oxide nanoparticles (TSS-SPIONs) for efficient internalization with high MRI sensitivity. TSS-SPIONs were developed by chelation between thiolated chitosan-thioglycolic acid (chitosan-TGA) hydrogel and iron ions (Fe(2+)/Fe(3+)). Likely, unmodified chitosan hydrogel SPIONs (UC-SPIONs) and uncoated SPIONs were used as control. Moreover, TSS-SPIONs were investigated regarding to their iron core size, hydrodynamic diameter, zeta potential, iron contents, molar relaxivities (r1 and r2), and cellular internalization. TSS-SPIONs demonstrated an iron oxide core diameter (crystallite size by XRD) of 3.1 ± 0.02 nm, a hydrodynamic diameter of 94 ± 20 nm, a zeta potential of +21 ± 5 mV, and an iron content of 3.6 ± 0.9 mg/mL. In addition, internalization of TSS-SPIONs into human endothelial progenitor cells (EPC) from umbilical cord blood was more than threefold and 17-fold higher in contrast to UC-SPIONs and SPIONs, respectively. With twofold lower incubation iron concentration of TSS-SPIONs, more than threefold higher internalization was achieved as compared to Resovist®. Also, cell viability of more than 90% was observed in the presence of TSS-SPIONs after 24h. The molar MR relaxivities (r2) value at 1.5 T was threefold higher than that of Resovist® and demonstrated that TSS-SPIONs have the potential as very effective T2 contrast-enhancement agent. According to these findings, TSS-SPIONs with efficient internalization, lower cytotoxicity, and high MRI sensitivity seem to be promising for cell tracking. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Surface functionalization of superparamagnetic nanoparticles encapsulated by chitosan for protein immobilization

    International Nuclear Information System (INIS)

    Sousa, Jose Silva de

    2010-01-01

    Nanoscience and nanotechnology have opened up numerous developments of devices and systems on the nanometer scale, with new molecular organization, properties and functions. In this context, the polymeric magnetic nanoparticles are composites formed by magnetic materials with a particle size between 1 and 100 nm combined with functional polymers. They are well-known and have been widely studied because of its applications in various technology areas. Applications on the biological and medical areas include separation and immobilization of enzymes and proteins, improved techniques of magnetic resonance imaging and diagnostic systems for controlled drug delivery. In this work, proteins were immobilized on the surface of a biopolymer combined with superparamagnetic particles of magnetite. The biopolymer chitosan was used, cross-linked and functionalized with glutaraldehyde, applicable to the biological assays. Three types of magnetic composites were obtained, which were called QM1Glu, QM2NaGlu and QM3Glu. They were characterized by X-ray diffraction, scanning electron microscopy, vibrating sample magnetometry, differential scanning calorimetry, thermogravimetry and infrared spectroscopy. They were evaluated concerning the immobilization of the proteins bovine serum albumin (BSA), collagen and trypsin. The study showed that the immobilization of proteins on the biopolymer occurred in 30 min of incubation. The magnetic composite of non functionalized chitosan (QM3) was also evaluated. For trypsin, it was found that the immobilization potential of QM3 was higher than that observed for QM3Glu. After 30 days, the trypsin of the QM3-Trip and QM3Glu-Trip was still with activity. The activity and the enzyme kinetics of the QM3Glu-Trip with the substrate BApNA were demonstrated. (author)

  10. Adsorption of superparamagnetic iron oxide nanoparticles on silica and calcium carbonate sand.

    Science.gov (United States)

    Park, Yoonjee C; Paulsen, Jeffrey; Nap, Rikkert J; Whitaker, Ragnhild D; Mathiyazhagan, Vidhya; Song, Yi-Qiao; Hürlimann, Martin; Szleifer, Igal; Wong, Joyce Y

    2014-01-28

    Superparamagnetic iron oxide (SPIO) nanoparticles have the potential to be used in the characterization of porous rock formations in oil fields as a contrast agent for NMR logging because they are small enough to traverse through nanopores and enhance contrast by shortening NMR T2 relaxation time. However, successful development and application require detailed knowledge of particle stability and mobility in reservoir rocks. Because nanoparticle adsorption to sand (SiO2) and rock (often CaCO3) affects their mobility, we investigated the thermodynamic equilibrium adsorption behavior of citric acid-coated SPIO nanoparticles (CA SPIO NPs) and poly(ethylene glycol)-grafted SPIO nanoparticles (PEG SPIO NPs) on SiO2 (silica) and CaCO3 (calcium carbonate). Adsorption behavior was determined at various pH and salt conditions via chemical analysis and NMR, and the results were compared with molecular theory predictions. Most of the NPs were recovered from silica, whereas far fewer NPs were recovered from calcium carbonate because of differences in the mineral surface properties. NP adsorption increased with increasing salt concentration: this trend was qualitatively explained by molecular theory, as was the role of the PEG grafting in preventing NPs adsorption. Quantitative disagreement between the theoretical predictions and the data was due to NP aggregation, especially at high salt concentration and in the presence of calcium carbonate. Upon aggregation, NP concentrations as determined by NMR T2 were initially overestimated and subsequently corrected using the relaxation rate 1/T2, which is a function of aggregate size and fractal dimension of the aggregate. Our experimental validation of the theoretical predictions of NP adsorption to minerals in the absence of aggregation at various pH and salt conditions demonstrates that molecular theory can be used to determine interactions between NPs and relevant reservoir surfaces. Importantly, this integrated experimental and

  11. Clinical evaluation of multishot echo planar imaging after administration of superparamagnetic iron oxide for hepatic tumors

    International Nuclear Information System (INIS)

    Sugai, Yukio; Watanabe, Yorihisa; Ito, Kazushi; Hosoya, Takaaki; Yamaguchi, Koichi

    1998-01-01

    Ten cases of hepatocellular carcinoma and three cases of metastatic liver tumor were evaluated using breath-hold multishot echo planar imaging (EPI) before and after administration of super-paramagnetic iron oxide (SPIO), and the results were compared to those with breath-hold fast multi-planar SPGR (T 1 WI) and fat-suppressed respiratory-triggered FSE (T 2 WI). Qualitative imaging evaluation of lesion detectability showed that T 2 WI was much more useful than T 1 WI as previously reported, and more useful than EPI. Quantitative evaluation showed that the signal to noise (S/N) ratios of the liver parenchyma decreased after administration of SPIO and the changes were significant on all pulse sequences. The change ratio of the S/N ratio of the liver parenchyma after administration of SPIO on EPI was significantly higher than on T 1 WI and T 2 WI. The tumor-liver contrast to noise (C/N) ratios increased after administration of SPIO and the changes were significant on T 1 WI and T 2 WI, but not on EPI. These results suggested that the tumor S/N ratio decreased after administration of SPIO on EPI. The tumor diameters on EPI were significantly reduced after administration of SPIO. Magnetization and flow artifacts on EPI were detected in all cases and caused distortion: the signal decreased in the liver parenchyma. We concluded that EPI after administration of SPIO is not currently useful compared to other pulse sequences and cannot yet replace T 2 WI. (author)

  12. The Effect of Superparamagnetic Iron Oxide Nanoparticle Surface Charge on Antigen Cross-Presentation

    Science.gov (United States)

    Mou, Yongbin; Xing, Yun; Ren, Hongyan; Cui, Zhihua; Zhang, Yu; Yu, Guangjie; Urba, Walter J.; Hu, Qingang; Hu, Hongming

    2017-01-01

    Magnetic nanoparticles (NPs) of superparamagnetic iron oxide (SPIO) have been explored for different kinds of applications in biomedicine, mechanics, and information. Here, we explored the synthetic SPIO NPs as an adjuvant on antigen cross-presentation ability by enhancing the intracellular delivery of antigens into antigen presenting cells (APCs). Particles with different chemical modifications and surface charges were used to study the mechanism of action of antigen delivery. Specifically, two types of magnetic NPs, γFe2O3/APTS (3-aminopropyltrimethoxysilane) NPs and γFe2O3/DMSA (meso-2, 3-Dimercaptosuccinic acid) NPs, with the same crystal structure, magnetic properties, and size distribution were prepared. Then, the promotion of T-cell activation via dendritic cells (DCs) was compared among different charged antigen coated NPs. Moreover, the activation of the autophagy, cytosolic delivery of the antigens, and antigen degradation mediated by the proteasome and lysosome were measured. Our results indicated that positive charged γFe2O3/APTS NPs, but not negative charged γFe2O3/DMSA NPs, enhanced the cross-presentation ability of DCs. Increased cross-presentation ability induced by γFe2O3/APTS NPs was associated with increased cytosolic antigen delivery. On the contrary, γFe2O3/DMSA NPs was associated with rapid autophagy. Overall, our results suggest that antigen delivered in cytoplasm induced by positive charged particles is beneficial for antigen cross-presentation and T-cell activation. NPs modified with different chemistries exhibit diverse biological properties and differ greatly in their adjuvant potentials. Thus, it should be carefully considered many different effects of NPs to design effective and safe adjuvants.

  13. A method for determination of [Fe3+]/[Fe2+] ratio in superparamagnetic iron oxide

    Science.gov (United States)

    Jiang, Changzhao; Yang, Siyu; Gan, Neng; Pan, Hongchun; Liu, Hong

    2017-10-01

    Superparamagnetic iron oxide nanoparticles (SPION), as a kind of nanophase materials, are widely used in biomedical application, such as magnetic resonance imaging (MRI), drug delivery, and magnetic field assisted therapy. The magnetic property of SPION has close connection with its crystal structure, namely it is related to the ratio of Fe3+ and Fe2+ which form the SPION. So a simple way to determine the content of the Fe3+ and Fe2+ is important for researching the property of SPION. This review covers a method for determination of the Fe3+ and Fe2+ ratio in SPION by UV-vis spectrophotometry based the reaction of Fe2+ and 1,10-phenanthroline. The standard curve of Fe with R2 = 0.9999 is used for determination the content of Fe2+ and total iron with 2.5 mL 0.01% (w/v) SPION digested by HCl, pH = 4.30 HOAc-NaAc buffer 10 mL, 0.01% (w/v) 1,10-phenanthroline 5 mL and 10% (w/v) ascorbic acid 1 mL for total iron determine independently. But the presence of Fe3+ interfere with obtaining the actual value of Fe2+ (the error close to 9%). We designed a calibration curve to eliminate the error by devising a series of solution of different ratio of [Fe3+]/[Fe2+], and obtain the calibration curve. Through the calibration curve, the error between the measured value and the actual value can be reduced to 0.4%. The R2 of linearity of the method is 0.99441 and 0.99929 for Fe2+ and total iron respectively. The error of accuracy of recovery and precision of inter-day and intra-day are both lower than 2%, which can prove the reliability of the determination method.

  14. Theory, simulation and experimental results of the acoustic detection of magnetization changes in superparamagnetic iron oxide

    Directory of Open Access Journals (Sweden)

    Borgert Jörn

    2011-06-01

    Full Text Available Abstract Background Magnetic Particle Imaging is a novel method for medical imaging. It can be used to measure the local concentration of a tracer material based on iron oxide nanoparticles. While the resulting images show the distribution of the tracer material in phantoms or anatomic structures of subjects under examination, no information about the tissue is being acquired. To expand Magnetic Particle Imaging into the detection of soft tissue properties, a new method is proposed, which detects acoustic emissions caused by magnetization changes in superparamagnetic iron oxide. Methods Starting from an introduction to the theory of acoustically detected Magnetic Particle Imaging, a comparison to magnetically detected Magnetic Particle Imaging is presented. Furthermore, an experimental setup for the detection of acoustic emissions is described, which consists of the necessary field generating components, i.e. coils and permanent magnets, as well as a calibrated microphone to perform the detection. Results The estimated detection limit of acoustic Magnetic Particle Imaging is comparable to the detection limit of magnetic resonance imaging for iron oxide nanoparticles, whereas both are inferior to the theoretical detection limit for magnetically detected Magnetic Particle Imaging. Sufficient data was acquired to perform a comparison to the simulated data. The experimental results are in agreement with the simulations. The remaining differences can be well explained. Conclusions It was possible to demonstrate the detection of acoustic emissions of magnetic tracer materials in Magnetic Particle Imaging. The processing of acoustic emission in addition to the tracer distribution acquired by magnetic detection might allow for the extraction of mechanical tissue parameters. Such parameters, like for example the velocity of sound and the attenuation caused by the tissue, might also be used to support and improve ultrasound imaging. However, the method

  15. Atherosclerotic imaging using 4 types of superparamagnetic iron oxides: New possibilities for mannan-coated particles

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, Keiko, E-mail: keikot@belle.shiga-medac.jp [Department of Radiology, Shiga University of Medical Science, Setatsukinowa-cho, Otsu, Shiga 520-2192 (Japan); Nitta, Norihisa, E-mail: r34nitta@yahoo.co.jp [Department of Radiology, Shiga University of Medical Science, Setatsukinowa-cho, Otsu, Shiga 520-2192 (Japan); Sonoda, Akinaga, E-mail: akinagasonoda@yahoo.co.jp [Department of Radiology, Shiga University of Medical Science, Setatsukinowa-cho, Otsu, Shiga 520-2192 (Japan); Otani, Hideji, E-mail: otani@belle.shiga-med.ac.jp [Department of Radiology, Shiga University of Medical Science, Setatsukinowa-cho, Otsu, Shiga 520-2192 (Japan); Takahashi, Masashi, E-mail: masashi@belle.shiga-med.ac.jp [Department of Radiology, Shiga University of Medical Science, Setatsukinowa-cho, Otsu, Shiga 520-2192 (Japan); Murata, Kiyoshi, E-mail: murata@belle.shiga-med.ac.jp [Department of Radiology, Shiga University of Medical Science, Setatsukinowa-cho, Otsu, Shiga 520-2192 (Japan); Shiomi, Masashi, E-mail: ieakusm@med.kobe-u.ac.jp [Institute for Experimental Animals, Kobe University School of Medicine, 7-5-1 Kusunoki-cho, Tyuoku, Kobe, Hyogo 650-0017 (Japan); Tabata, Yasuhiko, E-mail: yasuhiko@frontier.kyoto-u.ac.jp [Department of Biomaterials, Institute for Frontier Medical Sciences, Kyoto University, 53 Syogoin-Kawahara-cho, Sakyoku, Kyoto 606-8507 (Japan); Nohara, Satoshi, E-mail: s-nohara@meito-sangyo.co.jp [The Nagoya Research Laboratory, Meito Sangyo Co., Ltd., 25-5 Nishibiwajima-cho, Kiyosu, Aichi 452-0067 (Japan)

    2013-11-01

    Purpose: We used magnetic resonance imaging (MRI) and histologic techniques to compare the uptake by the rabbit atherosclerotic wall of 4 types of superparamagnetic iron oxide (SPIO) particles, i.e. SPIO, mannan-coated SPIO (M-SPIO), ultrasmall SPIO (USPIO), and mannan-coated USPIO (M-USPIO). Materials and methods: All experimental protocols were approved by our institutional animal experimentation committee. We intravenously injected 12 Watanabe heritable hyperlipidemic rabbits with one of the 4 types of SPIO (0.8 mmol Fe/kg). Two other rabbits served as the control. The rabbits underwent in vivo contrast-enhanced magnetic resonance angiography (MRA) before- and 5 days after these injections; excised aortae were subjected to in vitro MRI. In the in vivo and in vitro studies we assessed the signal intensity of the vessels at identical regions of interest (ROI) and calculated the signal-to-noise ratio (SNR). For histologic assessment we evaluated the iron-positive regions in Prussian blue-stained specimens. Results: There were significant differences in iron-positive regions where M-USPIO > USPIO, M-SPIO > SPIO, USPIO > SPIO (p < 0.05) but not between M-USPIO and M-SPIO. The difference between the pre- and post-injection SNR was significantly greater in rabbits treated with M-USPIO than USPIO and in rabbits injected with M-SPIO than SPIO (p < 0.05). On in vitro MRI scans SNR tended to be lower in M-USPIO- and M-SPIO- than USPIO- and SPIO-treated rabbits (p < 0.1). Conclusion: Histologic and imaging analysis showed that mannan-coated SPIO and USPIO particles were taken up more readily by the atherosclerotic rabbit wall than uncoated SPIO and USPIO.

  16. Biodistribution of ultra small superparamagnetic iron oxide nanoparticles in BALB mice

    International Nuclear Information System (INIS)

    Saeed Shanehsazzadeh; Mohammad Ali Oghabian; Tehran University of Medical Science, Tehran; Fariba Johari Daha; Massoud Amanlou; Allen, B.J.

    2013-01-01

    Recently ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles (NPs) have been widely used for medical applications. One of their important applications is using these particles as MRI contrast agent. While various research works have been done about MRI application of USPIOs, there is limited research about their uptakes in various organs. The aim of this study was to evaluate the biodistribution of dextran coated iron oxide NPs labelled with 99m Tc in various organs via intravenous injection in Balb/c mice. The magnetite NPs were dispersed in phosphate buffered saline and SnCl 2 which was used as a reduction reagent. Subsequently, the radioisotope 99m Tc was mixed directly into the reaction solution. The labeling efficiency of USPIOs labeled with 99m Tc, was above 99 %. Sixty mice were sacrificed at 12 different time points (From 1 min to 48 h post injections; five mice at each time). The percentage of injected dose per gram of each organ was measured by direct counting for 19 harvested organs of the mice. The biodistribution of 99m Tc-USPIO in Balb/c mice showed dramatic uptake in reticuloendothelial system. Accordingly, about 75 percent of injected dose was found in spleen and liver at 15 min post injection. More than 24 % of the NPs remain in liver after 48 h post-injection and their clearance is so fast in other organs. The results suggest that USPIOs as characterized in our study can be potentially used as contrast agent in MR Imaging, distributing reticuloendothelial system specially spleen and liver. (author)

  17. Investigation on the toxic interaction of superparamagnetic iron oxide nanoparticles with catalase

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Zehua [Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, China–America CRC for Environment and Health, Shandong Province, Shandong University, 27# Shanda South Road, Jinan 250100 (China); Liu, Hongwei [Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, China–America CRC for Environment and Health, Shandong Province, Shandong University, 27# Shanda South Road, Jinan 250100 (China); Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Hu, Xinxin; Song, Wei [Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, China–America CRC for Environment and Health, Shandong Province, Shandong University, 27# Shanda South Road, Jinan 250100 (China); Liu, Rutao, E-mail: rutaoliu@sdu.edu.cn [Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, China–America CRC for Environment and Health, Shandong Province, Shandong University, 27# Shanda South Road, Jinan 250100 (China)

    2015-03-15

    Superparamagnetic iron oxide nanoparticles (SPIONs) have been investigated for various applications in targeted drug delivery and magnetic resonance imaging. Given their clinical relevance, there is a need to understand these particles' potential cytotoxic effects and possible mechanisms of cytotoxicity. Using a variety of spectroscopic techniques, we investigated the interaction of SPIONs with catalase (CAT) in an aqueous environment. Catalase is an important enzyme that protects cells and tissues from oxidative damage by reactive oxygen species (ROS). Therefore, in this work, CAT served as a model protein for examining the physiological effects of SPIONs due to is function in eliminating H{sub 2}O{sub 2}. Synchronous fluorescence spectroscopy results showed that SPIONs have little effect on tryptophan residues in CAT. Data from circular dichroism (CD) and UV–vis spectroscopies showed that CAT α-helical content decreased from 32.4% to 29.1% in the presence of SPIONs. Moreover, a ca. 10% decrease in CAT activity was observed in the presence of SPIONs at a 20:1 particle:protein ratio. These results show that SPIONs can interact with proteins to alter both their structure and function. Further studies with CAT or other toxicologically relevant enzymes may be used for elucidating the mechanisms of SPION cytotoxicity. - Highlights: • This work established the binding mode of SPIONs with CAT on molecular level. • The interaction mechanism was explored by multiple spectroscopic techniques. • SPIONs can loosen the skeleton of protein and increase the exposure of amide moieties in the hydrophobic pocket. • SPIONs can inhibit CAT activity and trigger conformational changes in CAT.

  18. Surface modified superparamagnetic nanoparticles: Interaction with fibroblasts in primary cell culture

    Energy Technology Data Exchange (ETDEWEB)

    Chapa Gonzalez, Christian; Roacho Pérez, Jorge A.; Martínez Pérez, Carlos A.; Olivas Armendáriz, Imelda [Instituto de Ingeniería y Tecnología, Universidad Autónoma de Ciudad Juárez, Ave. Del Charro #610 norte, Col. Partido Romero, C.P. 32320 Cd. Juárez, Chihuahua, México (Mexico); Jimenez Vega, Florinda [Instituto de Ciencias Biomédicas, Universidad Autónoma de Ciudad Juárez, Anillo envolvente del PRONAF y Estocolmo, C.P. 32320 Cd. Juárez, Chihuahua, México (Mexico); Castrejon Parga, Karen Y. [Instituto de Ingeniería y Tecnología, Universidad Autónoma de Ciudad Juárez, Ave. Del Charro #610 norte, Col. Partido Romero, C.P. 32320 Cd. Juárez, Chihuahua, México (Mexico); Garcia Casillas, Perla E., E-mail: pegarcia@uacj.mx [Instituto de Ingeniería y Tecnología, Universidad Autónoma de Ciudad Juárez, Ave. Del Charro #610 norte, Col. Partido Romero, C.P. 32320 Cd. Juárez, Chihuahua, México (Mexico)

    2014-12-05

    Highlights: • An inorganic layer before an organic material shell onto MNPs improves cell viability. • The coating type and the concentration of nanoparticles directly affect cell viability. • Modified magnetite nanoparticles with organic and inorganic materials was developed. - Abstract: The development of a variety of medical applications such as drug delivery, cell labeling, and medical imaging have been possible owing to the unique features exhibited by magnetic nanoparticles. Nanoparticle–cell interaction is related to the surface aspects of nanoparticle, which may be described based on their chemistry or inorganic/organic characteristics. The coating on particle surface reduces the inter-particle interactions and provides properties such as biocompatibility. Among the coating materials used for nanoparticles employed in biomedical applications, oleic acid is one of the most utilized due to its biocompatibility. However, a major drawback with this naturally occurring fatty acid is that it is easily oxidized by cells and this reduces their performance in biomedical applications. In order to avoid the direct contact of the cell with the magnetite particle, coating with an inorganic material prior to the oleic acid shell would be effective. This would retard the magnetite dissociation thereby improve the cell viability. Here we report our investigation on the effect of surface modified magnetite nanoparticles (MNPs) on the cell viability using primary cultures incubated with those particles. We prepared magnetite nanoparticles by chemical co-precipitation method; nanoparticle surface was first modified by silanol condensation followed by chemisorption of oleic acid. All nanostructures have a particle size less than 100 nm, depending on the material coating and superparamagnetic behavior. The saturated magnetizations (M{sub s}) of the magnetite samples coated with oleic acid (MAO; 49.15 emu/g) and double shell silica-oleic acid (MSAO; 46.16 emu/g) are

  19. Investigation on the toxic interaction of superparamagnetic iron oxide nanoparticles with catalase

    International Nuclear Information System (INIS)

    Yu, Zehua; Liu, Hongwei; Hu, Xinxin; Song, Wei; Liu, Rutao

    2015-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) have been investigated for various applications in targeted drug delivery and magnetic resonance imaging. Given their clinical relevance, there is a need to understand these particles' potential cytotoxic effects and possible mechanisms of cytotoxicity. Using a variety of spectroscopic techniques, we investigated the interaction of SPIONs with catalase (CAT) in an aqueous environment. Catalase is an important enzyme that protects cells and tissues from oxidative damage by reactive oxygen species (ROS). Therefore, in this work, CAT served as a model protein for examining the physiological effects of SPIONs due to is function in eliminating H 2 O 2 . Synchronous fluorescence spectroscopy results showed that SPIONs have little effect on tryptophan residues in CAT. Data from circular dichroism (CD) and UV–vis spectroscopies showed that CAT α-helical content decreased from 32.4% to 29.1% in the presence of SPIONs. Moreover, a ca. 10% decrease in CAT activity was observed in the presence of SPIONs at a 20:1 particle:protein ratio. These results show that SPIONs can interact with proteins to alter both their structure and function. Further studies with CAT or other toxicologically relevant enzymes may be used for elucidating the mechanisms of SPION cytotoxicity. - Highlights: • This work established the binding mode of SPIONs with CAT on molecular level. • The interaction mechanism was explored by multiple spectroscopic techniques. • SPIONs can loosen the skeleton of protein and increase the exposure of amide moieties in the hydrophobic pocket. • SPIONs can inhibit CAT activity and trigger conformational changes in CAT

  20. Hyaluronan-modified superparamagnetic iron oxide nanoparticles for bimodal breast cancer imaging and photothermal therapy

    Directory of Open Access Journals (Sweden)

    Yang R

    2016-12-01

    Full Text Available Rui-Meng Yang,1,* Chao-Ping Fu,2,* Jin-Zhi Fang,1 Xiang-Dong Xu,1 Xin-Hua Wei,1 Wen-Jie Tang,1 Xin-Qing Jiang,1 Li-Ming Zhang2 1Department of Radiology, Guangzhou First People’s Hospital, Guangzhou Medical University, 2School of Materials Science and Engineering, School of Chemistry, Sun Yat-sen University, Guangzhou, China *These authors contributed equally to this work Abstract: Theranostic nanoparticles with both imaging and therapeutic abilities are highly promising in successful diagnosis and treatment of the most devastating cancers. In this study, the dual-modal imaging and photothermal effect of hyaluronan (HA-modified superparamagnetic iron oxide nanoparticles (HA-SPIONs, which was developed in a previous study, were investigated for CD44 HA receptor-overexpressing breast cancer in both in vitro and in vivo experiments. Heat is found to be rapidly generated by near-infrared laser range irradiation of HA-SPIONs. When incubated with CD44 HA receptor-overexpressing MDA-MB-231 cells in vitro, HA-SPIONs exhibited significant specific cellular uptake and specific accumulation confirmed by Prussian blue staining. The in vitro and in vivo results of magnetic resonance imaging and photothermal ablation demonstrated that HA-SPIONs exhibited significant negative contrast enhancement on T2-weighted magnetic resonance imaging and photothermal effect targeted CD44 HA receptor-overexpressing breast cancer. All these results indicated that HA-SPIONs have great potential for effective diagnosis and treatment of cancer. Keywords: iron oxide nanoparticles, surface functionalization, bioactive glycosaminoglycan, magnetic resonance imaging, cellular uptake, breast carcinoma

  1. Metallurgical investigation of wire breakage of tyre bead grade

    Directory of Open Access Journals (Sweden)

    Piyas Palit

    2015-10-01

    Full Text Available Tyre bead grade wire is used for tyre making application. The wire is used as reinforcement inside the polymer of tyre. The wire is available in different size/section such as 1.6–0.80 mm thin Cu coated wire. During tyre making operation at tyre manufacturer company, wire failed frequently. In this present study, different broken/defective wire samples were collected from wire mill for detailed investigation of the defect. The natures of the defects were localized and similar in nature. The fracture surface was of finger nail type. Crow feet like defects including button like surface abnormalities were also observed on the broken wire samples. The defect was studied at different directions under microscope. Different advanced metallographic techniques have been used for detail investigation. The analysis revealed that, white layer of surface martensite was formed and it caused the final breakage of wire. In this present study we have also discussed about the possible reason for the formation of such kind of surface martensite (hard-phase.

  2. Exploring chemical reaction mechanisms through harmonic Fourier beads path optimization.

    Science.gov (United States)

    Khavrutskii, Ilja V; Smith, Jason B; Wallqvist, Anders

    2013-10-28

    Here, we apply the harmonic Fourier beads (HFB) path optimization method to study chemical reactions involving covalent bond breaking and forming on quantum mechanical (QM) and hybrid QM∕molecular mechanical (QM∕MM) potential energy surfaces. To improve efficiency of the path optimization on such computationally demanding potentials, we combined HFB with conjugate gradient (CG) optimization. The combined CG-HFB method was used to study two biologically relevant reactions, namely, L- to D-alanine amino acid inversion and alcohol acylation by amides. The optimized paths revealed several unexpected reaction steps in the gas phase. For example, on the B3LYP∕6-31G(d,p) potential, we found that alanine inversion proceeded via previously unknown intermediates, 2-iminopropane-1,1-diol and 3-amino-3-methyloxiran-2-ol. The CG-HFB method accurately located transition states, aiding in the interpretation of complex reaction mechanisms. Thus, on the B3LYP∕6-31G(d,p) potential, the gas phase activation barriers for the inversion and acylation reactions were 50.5 and 39.9 kcal∕mol, respectively. These barriers determine the spontaneous loss of amino acid chirality and cleavage of peptide bonds in proteins. We conclude that the combined CG-HFB method further advances QM and QM∕MM studies of reaction mechanisms.

  3. A novel magnet focusing plate for matrix-assisted laser desorption/ionization analysis of magnetic bead-bound analytes.

    Science.gov (United States)

    Gode, David; Volmer, Dietrich A

    2013-05-15

    Magnetic beads are often used for serum profiling of peptide and protein biomarkers. In these assays, the bead-bound analytes are eluted from the beads prior to mass spectrometric analysis. This study describes a novel matrix-assisted laser desorption/ionization (MALDI) technique for direct application and focusing of magnetic beads to MALDI plates by means of dedicated micro-magnets as sample spots. Custom-made MALDI plates with magnetic focusing spots were made using small nickel-coated neodymium micro-magnets integrated into a stainless steel plate in a 16 × 24 (384) pattern. For demonstrating the proof-of-concept, commercial C-18 magnetic beads were used for the extraction of a test compound (reserpine) from aqueous solution. Experiments were conducted to study focusing abilities, the required laser energies, the influence of a matrix compound, dispensing techniques, solvent choice and the amount of magnetic beads. Dispensing the magnetic beads onto the micro-magnet sample spots resulted in immediate and strong binding to the magnetic surface. Light microscope images illustrated the homogeneous distribution of beads across the surfaces of the magnets, when the entire sample volume containing the beads was pipetted onto the surface. Subsequent MALDI analysis of the bead-bound analyte demonstrated excellent and reproducible ionization yields. The surface-assisted laser desorption/ionization (SALDI) properties of the strongly light-absorbing γ-Fe2O3-based beads resulted in similar ionization efficiencies to those obtained from experiments with an additional MALDI matrix compound. This feasibility study successfully demonstrated the magnetic focusing abilities for magnetic bead-bound analytes on a novel MALDI plate containing small micro-magnets as sample spots. One of the key advantages of this integrated approach is that no elution steps from magnetic beads were required during analyses compared with conventional bead experiments. Copyright © 2013 John Wiley

  4. An Attempt to Shorten Loading Time of Epirubicin into DC Beads® Using Vibration and a Sieve

    International Nuclear Information System (INIS)

    Sonoda, Akinaga; Nitta, Norihisa; Yamamoto, Takefumi; Tomozawa, Yuki; Ohta, Shinichi; Watanabe, Shobu; Murata, Kiyoshi

    2017-01-01

    PurposeWe investigated the possibility of shortening the time required for loading epirubicin into calibrated polyvinyl alcohol-based hydrogel beads (DC Beads ® ) to be used for transarterial chemoembolization.MethodAfter separating the beads suspended in phosphate-buffered saline (PBS) solution by the use of a sieve (clearance 75 µm), epirubicin hydrochloride (EH) was loaded for 20, 30, or 60 s under vibration into DC beads. The EH loading rate into conventionally prepared (control) beads, i.e., beads loaded for 30 min without vibration, and vibration-loaded beads were calculated from the residual EH concentration in the bead-depleted EH solution. The amount of EH eluted from conventionally and vibration-loaded samples into a PBS solution (pH 7.0) was measured at 15 and 30 min and 1, 2, 6, 12, and 24 h. We also recorded the inhibitory effect of the PBS solution on the loading time. Using frozen sections, the EH load in the beads was evaluated visually under a fluorescence microscope.ResultsSpectrophotometry (495 nm) showed that the loading rate was 98.98 ± 0.34, 99.02 ± 0.32, and 99.50 ± 0.11 % with 20-, 30-, and 60-s vibration, respectively. The eluted rate was statistically similar between vibration- and statically loaded (control) beads. The PBS solution hampered EH loading into the beads. Visually, the distribution of EH in conventionally and vibration-loaded DC beads was similar.DiscussionThe use of vibration and the removal of PBS solution when epirubicin hydrochloride was loaded into DC beads dramatically shortened the loading time of epirubicin hydrochloride into DC beads.

  5. An Attempt to Shorten Loading Time of Epirubicin into DC Beads{sup ®} Using Vibration and a Sieve

    Energy Technology Data Exchange (ETDEWEB)

    Sonoda, Akinaga, E-mail: akinagasonoda@yahoo.co.jp; Nitta, Norihisa [Shiga University of Medical Science, Department of Radiology (Japan); Yamamoto, Takefumi [Shiga University of Medical Science, Central Research Laboratory (Japan); Tomozawa, Yuki; Ohta, Shinichi; Watanabe, Shobu; Murata, Kiyoshi [Shiga University of Medical Science, Department of Radiology (Japan)

    2017-04-15

    PurposeWe investigated the possibility of shortening the time required for loading epirubicin into calibrated polyvinyl alcohol-based hydrogel beads (DC Beads{sup ®}) to be used for transarterial chemoembolization.MethodAfter separating the beads suspended in phosphate-buffered saline (PBS) solution by the use of a sieve (clearance 75 µm), epirubicin hydrochloride (EH) was loaded for 20, 30, or 60 s under vibration into DC beads. The EH loading rate into conventionally prepared (control) beads, i.e., beads loaded for 30 min without vibration, and vibration-loaded beads were calculated from the residual EH concentration in the bead-depleted EH solution. The amount of EH eluted from conventionally and vibration-loaded samples into a PBS solution (pH 7.0) was measured at 15 and 30 min and 1, 2, 6, 12, and 24 h. We also recorded the inhibitory effect of the PBS solution on the loading time. Using frozen sections, the EH load in the beads was evaluated visually under a fluorescence microscope.ResultsSpectrophotometry (495 nm) showed that the loading rate was 98.98 ± 0.34, 99.02 ± 0.32, and 99.50 ± 0.11 % with 20-, 30-, and 60-s vibration, respectively. The eluted rate was statistically similar between vibration- and statically loaded (control) beads. The PBS solution hampered EH loading into the beads. Visually, the distribution of EH in conventionally and vibration-loaded DC beads was similar.DiscussionThe use of vibration and the removal of PBS solution when epirubicin hydrochloride was loaded into DC beads dramatically shortened the loading time of epirubicin hydrochloride into DC beads.

  6. A control system for uniform bead in fillet arc welding on tack welds

    International Nuclear Information System (INIS)

    Kim, Jae Woong; Lee, Jun Young

    2008-01-01

    Positioning a workpiece accurately and preventing weld distortion, tack welding is often adopted before main welding in the construction of welded structures. However, this tack weld deteriorates the final weld bead profile, so that the grinding process is usually performed for a uniform weld bead profile. In this study, a control system for uniform weld bead is proposed for the fillet arc welding on tack welds. The system consists of GMA welding machine, torch manipulator, laser vision sensor for measuring the tack weld size and the database for optimal welding conditions. Experiments have been performed for constructing the database and for evaluating the control capability of the system. It has been shown that the system has the capability to smooth the bead at the high level of quality

  7. One-step isolation of plasma membrane proteins using magnetic beads with immobilized concanavalin A

    DEFF Research Database (Denmark)

    Lee, Yu-Chen; Block, Gregory; Chen, Huiwen

    2008-01-01

    We have developed a simple method for isolating and purifying plasma membrane proteins from various cell types. This one-step affinity-chromatography method uses the property of the lectin concanavalin A (ConA) and the technique of magnetic bead separation to obtain highly purified plasma membrane...... proteins from crude membrane preparations or cell lines. ConA is immobilized onto magnetic beads by binding biotinylated ConA to streptavidin magnetic beads. When these ConA magnetic beads were used to enrich plasma membranes from a crude membrane preparation, this procedure resulted in 3.7-fold enrichment...... of plasma membrane marker 5'-nucleotidase activity with 70% recovery of the activity in the crude membrane fraction of rat liver. In agreement with the results of 5'-nucleotidase activity, immunoblotting with antibodies specific for a rat liver plasma membrane protein, CEACAM1, indicated that CEACAM1...

  8. CUTANEOUS SQUAMOUS CELL CARCINOMA IN A PANTHER CHAMELEON (FURCIFER PARDALIS) AND TREATMENT WITH CARBOPLATIN IMPLANTABLE BEADS.

    Science.gov (United States)

    Johnson, James G; Naples, Lisa M; Chu, Caroline; Kinsel, Michael J; Flower, Jennifer E; Van Bonn, William G

    2016-09-01

    A 3-yr-old male panther chameleon (Furcifer pardalis) presented with bilateral raised crusted skin lesions along the lateral body wall that were found to be carcinoma in situ and squamous cell carcinoma. Similar lesions later developed on the caudal body wall and tail. A subcutaneous implantable carboplatin bead was placed in the first squamous cell carcinoma lesion identified. Additional new lesions sampled were also found to be squamous cell carcinomas, and viral polymerase chain reaction was negative for papillomaviruses and herpesviruses. Significant skin loss would have resulted from excision of all the lesions, so treatment with only carboplatin beads was used. No adverse effects were observed. Lesions not excised that were treated with beads decreased in size. This is the first description of cutaneous squamous cell carcinoma and treatment with carboplatin implantable beads in a panther chameleon.

  9. Two-phase mixed media dielectric with macro dielectric beads for enhancing resistivity and breakdown strength

    Science.gov (United States)

    Falabella, Steven; Meyer, Glenn A; Tang, Vincent; Guethlein, Gary

    2014-06-10

    A two-phase mixed media insulator having a dielectric fluid filling the interstices between macro-sized dielectric beads packed into a confined volume, so that the packed dielectric beads inhibit electro-hydrodynamically driven current flows of the dielectric liquid and thereby increase the resistivity and breakdown strength of the two-phase insulator over the dielectric liquid alone. In addition, an electrical apparatus incorporates the two-phase mixed media insulator to insulate between electrical components of different electrical potentials. And a method of electrically insulating between electrical components of different electrical potentials fills a confined volume between the electrical components with the two-phase dielectric composite, so that the macro dielectric beads are packed in the confined volume and interstices formed between the macro dielectric beads are filled with the dielectric liquid.

  10. Investigation the influence of dietary fiber on the rheological properties of alginate beads

    Directory of Open Access Journals (Sweden)

    Z. Manev

    2015-03-01

    Full Text Available Abstract. During the current investigation experiments for the preparation of alginate beads with aqueous solutions of sodium alginate, calcium lactate or calcium dichloride and dietary fiber in different concentrations: inulin with varying degrees of polymerization, wheat bran and amidated apple pectin were carried out. The sodium alginate solutions were at constant concentration 3%, while calcium salts in 7% were applied for bead formation. It was proven that the rupture force of alginate beads was always higher than the pure model system regardless of the chemical structure of dietary fibers used. In the result of the carried research the dependence at a certain concentration was established at which the rupture force and deformation of the beads increased gradually.

  11. Magnetic bead micromixer: Influence of magnetic element geometry and field amplitude

    DEFF Research Database (Denmark)

    Lund-Olesen, Torsten; Buus, Bjarke B.; Howalt, Jakob

    2008-01-01

    A scheme for the silicon microfabrication of lab-on-a-chip systems with mixing based on dynamic plugs of magnetic beads is presented. The systems consist of a microfluidic channel integrated with a number of soft magnetic elements by the sides of the channel. The elements are magnetized by a homo......A scheme for the silicon microfabrication of lab-on-a-chip systems with mixing based on dynamic plugs of magnetic beads is presented. The systems consist of a microfluidic channel integrated with a number of soft magnetic elements by the sides of the channel. The elements are magnetized...... by a homogeneous external ac magnetic field. The systems are scalable with respect to the number of magnetic bead plugs and number of parallel channels, and thus they have high potential for use in biological separation using functionalized magnetic beads. The mixing efficiency is characterized for two different...

  12. Planar Hall effect sensor bridge geometries optimized for magnetic bead detection

    DEFF Research Database (Denmark)

    Østerberg, Frederik Westergaard; Rizzi, Giovanni; Henriksen, Anders Dahl

    2014-01-01

    Novel designs of planar Hall effect bridge sensors optimized for magnetic bead detection are presented and characterized. By constructing the sensor geometries appropriately, the sensors can be tailored to be sensitive to an external magnetic field, the magnetic field due to beads being magnetized...... by the sensor self-field or a combination thereof. The sensors can be made nominally insensitive to small external magnetic fields, while being maximally sensitive to magnetic beads, magnetized by the sensor self-field. Thus, the sensor designs can be tailored towards specific applications with minimal...... of the dynamic magnetic response of suspensions of magnetic beads with a nominal diameter of 80 nm are performed. Furthermore, a method to amplify the signal by appropriate combinations of multiple sensor segments is demonstrated....

  13. Evaluation of double drop beads pavement edge lines : SPR project description.

    Science.gov (United States)

    2009-01-01

    In UTCA projects 01465 and 04405, the retroreflectivities and the life cycle costs were measured and compared for standard Alabama Department of Transportation (ALDOT) thermoplastic edge : stripes that contained only one size of retroreflective beads...

  14. STUDY ON THE SYNTHESIS AND STRUCTURE OF MACRORETICULAR BEAD PAN/PVC IPN RESINS

    Institute of Scientific and Technical Information of China (English)

    LI Yanfeng; ZHUO Renxi

    1993-01-01

    Macroreticular bead PAN/PVC IPN reans with cyano and chloro groups were synthesized by interpenetrating polymerization of acrylonitrile, or acrylonitrile and divinylbenzene into a macroporous polyvinyl chloride bead. The composition and structure of the bead IPN resins have been investigated by means of FT-IR, NMR, SEM, mercury porosimetry and elemental analysis. During the process of interpenetrating polymerization, the chain propagation obeys Bernoullian statistical law, and no grafting polymerization has been observed. The content of cyano group in the resulting IPN resins can be adjusted by the amount of acrylonitrile added. The morphology of the IPN resins basically resembles that of the polyvinyl chloride bead,whereas the pore structures vary to a certain degree

  15. Rapid bead-based immunoassay for measurement of mannose-binding lectin

    DEFF Research Database (Denmark)

    Bay, J T; Garred, P

    2009-01-01

    have been developed more automated platforms for MBL analysis is urgently needed. To pursue this, we set out to develop a flexible bead-based MBL immunoassay. Serum was obtained from 98 healthy individuals and 50 patients investigated for possible immunodeficiencies. We used the Luminex xMAP bead array...... coefficient were found be 7.88% and 5.70%, respectively. A close correlation between the new assay and a reference MBL measurement ELISA was found (rho 0.9381, P bead-based assay was less sensitive to interfering anti-murine antibodies in the blood samples than when the antibodies employed were...... used in the reference polystyrene-based ELISA. The new assay could be performed in 3 h with less than 25 microl serum required of each sample. These results show that MBL can be measured readily using a bead-based platform, which may form an efficient basis for a multiplex approach to measure different...

  16. Tumour metastasis-associated gene profiling using one-dimensional microfluidic beads array

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Great efforts have been made on the early diagnosis and molecular mechanism research of tumour metastasis in recent years. In this paper, based on the one-dimensional microfluidic beads array, a novel platform for tumour metastasis-associated genes profiling has been developed by depositing nucleic acids functional beads in the microchannel. This platform is sensitive (limit of detection: 0.02 nmol/L) and can perform mRNAs analysis without PCR. Two human colon cancer cell lines (primary and metastatic) from the same patient were used as a model, and transcriptional expression profiling of multiple tumour metastasis-associated genes in these two cell lines was successfully achieved. Furthermore, the results obtained on the beads array were validated by RT-PCR. This novel beads array has advantages of high sensitivity, little sample consumption, short assay time, low cost and high throughput capability. It holds the potential in early diagnosis and mechanism research of tumour metastasis.

  17. Polyaniline coated magnetic carboxymethylcellulose beads for selective removal of uranium ions from aqueous solution

    International Nuclear Information System (INIS)

    Yakup Arica, M.; Gulay Bayramoglu; Gazi University, Ankara

    2016-01-01

    Magnetic carboxymethylcellulose (CMC) beads were prepared via ionic cross-linking. Then CMC beads were coated with polyaniline (PANI). The results of FTIR, SEM, DTA and N 2 adsorption-desorption demonstrated that aniline was successfully grafted onto the surface of mCMC beads. The potential use of the prepared adsorbent was used for removal of U(VI) ions. The determined maximum adsorption capacities of the mCMC and mCMC-g-PANI beads for U(VI) ions were 129.4 and 386.5 mg/g dry weight at pH 4.5, respectively. The thermodynamic parameters (ΔH°, ΔS° and ΔG°) were evaluated. The adsorbent systems were regenerated using 0.1 M HCl. (author)

  18. Effect of Welding Parameters on Dilution and Weld Bead Geometry in Cladding

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The effect of pulsed gas metal arc welding (GMAW) variables on the dilution and weld bead geometry in cladding X65 pipeline steel with 316L stainless steel was studied. Using a full factorial method, a series of experiments were carried out to know the effect of wire feed rate, welding speed, distance between gas nozzle and plate, and the vertical angle of welding on dilution and weld bead geometry. The findings indicate that the dilution of weld metal and its dimension i.e. width, height and depth increase with the feed rate, but the contact angle of the bead decreases first and then increases. Meantime, welding speed has an opposite effect except for dilution. There is an interaction effect between welding parameters at the contact angle. The results also show forehand welding or decreasing electrode extension decrease the angle of contact. Finally,a mathematical model is contrived to highlight the relationship between welding variables with dilution and weld bead geometry.

  19. Asynchronous Magnetic Bead Rotation (AMBR Microviscometer for Label-Free DNA Analysis

    Directory of Open Access Journals (Sweden)

    Yunzi Li

    2014-03-01

    Full Text Available We have developed a label-free viscosity-based DNA detection system, using paramagnetic beads as an asynchronous magnetic bead rotation (AMBR microviscometer. We have demonstrated experimentally that the bead rotation period is linearly proportional to the viscosity of a DNA solution surrounding the paramagnetic bead, as expected theoretically. Simple optical measurement of asynchronous microbead motion determines solution viscosity precisely in microscale volumes, thus allowing an estimate of DNA concentration or average fragment length. The response of the AMBR microviscometer yields reproducible measurement of DNA solutions, enzymatic digestion reactions, and PCR systems at template concentrations across a 5000-fold range. The results demonstrate the feasibility of viscosity-based DNA detection using AMBR in microscale aqueous volumes.

  20. Immobilization of catalase on chitosan and amino acid- modified chitosan beads.

    Science.gov (United States)

    Başak, Esra; Aydemir, Tülin

    2013-08-01

    Bovine liver catalase was covalently immobilized onto amino acid-modified chitosan beads. The beads were characterized with SEM, FTIR, TGA and the effects of immobilization on optimum pH and temperature, thermostability, reusability were evaluated. Immobilized catalase showed the maximal enzyme activity at pH 7.0 at 30°C. The kinetic parameters, Km and Vmax, for immobilized catalase on alanine-chitosan beads and lysine-chitosan beads were estimated to be 25.67 mM, 27 mM and 201.39 μmol H2O2/min, 197.50 μmol H2O2/min, respectively. The activity of the immobilized catalase on Ala-CB and Lys-CB retained 40% of its high initial activity after 100 times of reuse.