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  • 1.
    Agthe, Michael
    et al.
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Wetterskog, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Bergström, Lennart
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Following the Assembly of Iron Oxide Nanocubes by Video Microscopy and Quartz Crystal Microbalance with Dissipation Monitoring2017In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 33, no 1, p. 303-310Article in journal (Refereed)
    Abstract [en]

    We have studied the growth of ordered arrays by evaporation-induced self-assembly of iron oxide nanocubes with edge lengths of 6.8 and 10.1 nm using video microscopy (VM) and quartz crystal microbalance with dissipation monitoring (QCM-D). Ex situ electron diffraction of the ordered arrays demonstrates that the crystal axes of the nanocubes are coaligned and confirms that the ordered arrays are mesocrystals. Time-resolved video microscopy shows that growth of the highly ordered arrays at slow solvent evaporation is controlled by particle diffusion and can be described by a simple growth model. The growth of each mesocrystal depends only on the number of nanoparticles within the accessible region irrespective of the relative time of formation. The mass of the dried mesocrystals estimated from the analysis of the bandwidth-shift-to-frequency-shift ratio correlates well with the total mass of the oleate-coated nanoparticles in the deposited dispersion drop.

  • 2. Ahrentorp, Fredrik
    et al.
    Astalan, Andrea
    Blomgren, Jakob
    Jonasson, Christian
    Wetterskog, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Lak, Aidin
    Ludwig, Frank
    Van IJzendoorn, Leo J.
    Westphal, Fritz
    Gruettner, Cordula
    Gehrke, Nicole
    Gustafsson, Stefan
    Olsson, Eva
    Johansson, Christer
    Effective particle magnetic moment of multi-core particles2015In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 380, p. 221-226Article in journal (Refereed)
    Abstract [en]

    In this study we investigate the magnetic behavior of magnetic multi-core particles and the differences in the magnetic properties of multi-core and single-core nanoparticles and correlate the results with the nanostructure of the different particles as determined from transmission electron microscopy (TEM). We also investigate how the effective particle magnetic moment is coupled to the individual moments of the single-domain nanocrystals by using different measurement techniques: DC magnetometry, AC susceptometry, dynamic light scattering and TEM. We have studied two magnetic multi-core particle systems BNF Starch from Micromod with a median particle diameter of 100 am and FeraSpin R from nanoPET with a median particle diameter of 70 nm - and one single-core particle system - SHP25 from Ocean NanoTech with a median particle core diameter of 25 nm. (C) 2014 Elsevier B.V. All rights reserved.

  • 3.
    Bender, Philipp
    et al.
    Univ Cantabria, E-39005 Santander, Spain..
    Fock, Jeppe
    Tech Univ Denmark, DK-2800 Lyngby, Denmark..
    Frandsen, Cathrine
    Tech Univ Denmark, DK-2800 Lyngby, Denmark..
    Hansen, Mikkel F.
    Tech Univ Denmark, DK-2800 Lyngby, Denmark..
    Balceris, Christoph
    TU Braunschweig, D-38106 Braunschweig, Germany..
    Ludwig, Frank
    TU Braunschweig, D-38106 Braunschweig, Germany..
    Posth, Oliver
    Phys Tech Bundesanstalt, D-10587 Berlin, Germany..
    Wetterskog, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Bogart, Lara K.
    UCL, London W1S 4BS, England..
    Southern, Paul
    UCL, London W1S 4BS, England..
    Szczerba, Wojciech
    Bundesanstalt Mat Forsch & Prufung, D-12205 Berlin, Germany.;AGH Univ Sci & Technol, PL-30059 Krakow, Poland..
    Zeng, Lunjie
    Chalmers Univ Technol, S-41296 Gothenburg, Sweden..
    Witte, Kerstin
    Univ Rostock, D-18059 Rostock, Germany.;Micromod Partikeltechnol GmbH, D-18119 Rostock, Germany..
    Grüttner, Cordula
    Micromod Partikeltechnol GmbH, D-18119 Rostock, Germany..
    Westphal, Fritz
    Micromod Partikeltechnol GmbH, D-18119 Rostock, Germany..
    Honecker, Dirk
    Inst Laue Langevin, F-38042 Grenoble, France..
    Gonzalez-Alonso, David
    Univ Cantabria, E-39005 Santander, Spain..
    Fernandez Barquin, Luis
    Univ Cantabria, E-39005 Santander, Spain..
    Johansson, Christer
    RISE Acreo, S-40014 Gothenburg, Sweden..
    Relating Magnetic Properties and High Hyperthermia Performance of Iron Oxide Nanoflowers2018In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 5, p. 3068-3077Article in journal (Refereed)
    Abstract [en]

    We investigated, in depth, the interrelations among structure, magnetic properties, relaxation dynamics and magnetic hyperthermia performance of magnetic nanoflowers. The nanoflowers are about 39 nm in size, and consist of densely packed iron oxide cores. They display a remanent magnetization, which we explain by the exchange coupling between the cores, but we observe indications for internal spin disorder. By polarized small-angle neutron scattering, we unambiguously confirm that, on average, the nano flowers are preferentially magnetized along one direction. The extracted discrete relaxation time distribution of the colloidally dispersed particles indicates the presence of three distinct relaxation contributions. We can explain the two slower processes by Brownian and classical Neel relaxation, respectively. The additionally observed very fast relaxation contributions are attributed by us to the relaxation of disordered spins within the nanoflowers. Finally, we show that the intrinsic loss power (ILP, magnetic hyperthermia performance) of the nanoflowers measured in colloidal dispersion at high frequency is comparatively large and independent of the viscosity of the surrounding medium. This concurs with our assumption that the observed relaxation in the high frequency range is primarily a result of internal spin relaxation, and possibly connected to the disordered spins within the individual nanoflowers.

  • 4.
    Gavilan, Helena
    et al.
    ICMM CSIC, Inst Ciencia Mat Madrid, Dept Energy Environm & Hlth, Sor Juana Ines de la Cruz 3, Madrid 28049, Spain..
    Kowalski, Anja
    Micromod Partikeltechnol GmbH, Friedrich Barnewitz Str 4, D-18119 Rostock, Germany..
    Heinke, David
    NanoPET Pharma GmbH, D-10115 Berlin, Germany..
    Sugunan, Abhilash
    Swedish Res Inst, Box 5607, SE-11486 Stockholm, Sweden..
    Sommertune, Jens
    Swedish Res Inst, Box 5607, SE-11486 Stockholm, Sweden..
    Varon, Miriam
    Tech Univ Denmark, Dept Phys, DK-2800 Lyngby, Denmark..
    Bogart, Lara K.
    UCL, Healthcare Biomagnet Lab, 21 Albemarle St, London W1S 4BS, England..
    Posth, Oliver
    Phys Tech Bundesanstalt, Abbestr 2-12, D-10587 Berlin, Germany..
    Zeng, Lunjie
    Chalmers, Dept Appl Phys, SE-41296 Gothenburg, Sweden..
    Gonzalez-Alonso, David
    Univ Cantabria, Dept CITIMAC, E-39005 Santander, Spain..
    Balceris, Christoph
    TU Braunschweig, Inst Elect Measurement & Fundamental Elect Engn, D-38106 Braunschweig, Germany..
    Fock, Jeppe
    Tech Univ Denmark, Dept Micro & Nanotechnol, DK-2800 Lyngby, Denmark..
    Wetterskog, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Frandsen, Cathrine
    Tech Univ Denmark, Dept Phys, DK-2800 Lyngby, Denmark..
    Gehrke, Nicole
    NanoPET Pharma GmbH, D-10115 Berlin, Germany..
    Gruettner, Cordula
    Micromod Partikeltechnol GmbH, Friedrich Barnewitz Str 4, D-18119 Rostock, Germany..
    Fornara, Andrea
    Swedish Res Inst, Box 5607, SE-11486 Stockholm, Sweden..
    Ludwig, Frank
    TU Braunschweig, Inst Elect Measurement & Fundamental Elect Engn, D-38106 Braunschweig, Germany..
    Veintemillas-Verdaguer, Sabino
    ICMM CSIC, Inst Ciencia Mat Madrid, Sor Juana Ines de la Cruz 3, Madrid 28049, Spain..
    Johansson, Christer
    RISE Acreo, POB 53071, SE-40014 Gothenburg, Sweden..
    Puerto Morales, M.
    ICMM CSIC, Inst Ciencia Mat Madrid, Dept Energy Environm & Hlth, Sor Juana Ines de la Cruz 3, Madrid 28049, Spain..
    Colloidal Flower-Shaped Iron Oxide Nanoparticles: Synthesis Strategies and Coatings2017In: Particle & particle systems characterization, ISSN 0934-0866, E-ISSN 1521-4117, Vol. 34, no 7, article id 1700094Article in journal (Refereed)
    Abstract [en]

    The assembly of magnetic cores into regular structures may notably influence the properties displayed by a magnetic colloid. Here, key synthesis parameters driving the self-assembly process capable of organizing colloidal magnetic cores into highly regular and reproducible multi-core nanoparticles are determined. In addition, a self-consistent picture that explains the collective magnetic properties exhibited by these complex assemblies is achieved through structural, colloidal, and magnetic means. For this purpose, different strategies to obtain flower-shaped iron oxide assemblies in the size range 25-100 nm are examined. The routes are based on the partial oxidation of Fe(OH)(2), polyol-mediated synthesis or the reduction of iron acetylacetonate. The nanoparticles are functionalized either with dextran, citric acid, or alternatively embedded in polystyrene and their long-term stability is assessed. The core size is measured, calculated, and modeled using both structural and magnetic means, while the Debye model and multi-core extended model are used to study interparticle interactions. This is the first step toward standardized protocols of synthesis and characterization of flower-shaped nanoparticles.

  • 5.
    Herlitschke, M.
    et al.
    DESY, FS PE, D-22607 Hamburg, Germany.;Forschungszentrum Julich, JCNS, JARA FIT, D-52425 Julich, Germany.;Forschungszentrum Julich, PGI, JARA FIT, D-52425 Julich, Germany.;Univ Liege, Fac Sci, B-4000 Liege, Belgium..
    Disch, S.
    Univ Cologne, Dept Chem, D-50939 Cologne, Germany.;Inst Laue Langevin, F-38042 Grenoble, France..
    Sergueev, I.
    DESY, FS PE, D-22607 Hamburg, Germany..
    Schlage, K.
    DESY, FS PE, D-22607 Hamburg, Germany..
    Wetterskog, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Bergstrom, L.
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Hermann, R. P.
    Forschungszentrum Julich, JCNS, JARA FIT, D-52425 Julich, Germany.;Forschungszentrum Julich, PGI, JARA FIT, D-52425 Julich, Germany.;Univ Liege, Fac Sci, B-4000 Liege, Belgium.;Oak Ridge Natl Lab, Mat Sci & Technol Div, Oak Ridge, TN 37831 USA..
    Spin disorder in maghemite nanoparticles investigated using polarized neutrons and nuclear resonant scattering2016In: International Conference On Polarised Neutrons For Condensed Matter Investigations (PNCMI 2014), 2016Conference paper (Refereed)
    Abstract [en]

    The manuscript reports the investigation of spin disorder in maghemite nanoparticles of different shape by a combination of polarized small -angle neutron scattering (SANSPOL) and nuclear forward scattering (NFS) techniques. Both methods are sensitive to magnetization on the nanoscale. SANSPOL allows for investigation of the particle morphology and spatial magnetization distribution and NFS extends this nanoscale information to the atomic scale, namely the orientation of the hyperfine field experienced by the iron nuclei. The studied nanospheres and nanocubes with diameters of 7.4nm and 10.6 nm, respectively, exhibit a significant spin disorder. This effect leads to a reduction of the magnetization to 44 % and 58% of the theoretical maghemite bulk value, observed consistently by both techniques.

  • 6.
    Josten, Elisabeth
    et al.
    Forschungszentrum Julich, JCNS, D-52425 Julich, Germany.;Forschungszentrum Julich, PGI, JARA FIT, D-52425 Julich, Germany.;Helmholtz Zentrum Dresden Rossendorf, Inst Ion Beam Phys & Mat Res, D-01328 Dresden, Germany..
    Wetterskog, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Glavic, Artur
    Forschungszentrum Julich, JCNS, D-52425 Julich, Germany.;Forschungszentrum Julich, PGI, JARA FIT, D-52425 Julich, Germany.;Paul Scherrer Inst, Lab Neutron Scattering & Imaging, CH-5232 Villigen, Switzerland..
    Boesecke, Peter
    ESRF European Synchrotron, F-38043 Grenoble, France..
    Feoktystov, Artem
    Forschungszentrum Julich, Heinz Maier Leibnitz Zentrum MLZ, JCNS, D-85747 Garching, Germany..
    Brauweiler-Reuters, Elke
    Forschungszentrum Julich, Bioelect ICS 8, Inst Complex Syst, D-52425 Julich, Germany..
    Ruecker, Ulrich
    Forschungszentrum Julich, JCNS, D-52425 Julich, Germany.;Forschungszentrum Julich, PGI, JARA FIT, D-52425 Julich, Germany..
    Salazar-Alvarez, German
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Brueckel, Thomas
    Forschungszentrum Julich, JCNS, D-52425 Julich, Germany.;Forschungszentrum Julich, PGI, JARA FIT, D-52425 Julich, Germany..
    Bergstrom, Lennart
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Superlattice growth and rearrangement during evaporation-induced nanoparticle self-assembly2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 2802Article in journal (Refereed)
    Abstract [en]

    Understanding the assembly of nanoparticles into superlattices with well-defined morphology and structure is technologically important but challenging as it requires novel combinations of in-situ methods with suitable spatial and temporal resolution. In this study, we have followed evaporation-induced assembly during drop casting of superparamagnetic, oleate-capped gamma-Fe2O3 nanospheres dispersed in toluene in real time with Grazing Incidence Small Angle X-ray Scattering (GISAXS) in combination with droplet height measurements and direct observation of the dispersion. The scattering data was evaluated with a novel method that yielded time-dependent information of the relative ratio of ordered (coherent) and disordered particles (incoherent scattering intensities), superlattice tilt angles, lattice constants, and lattice constant distributions. We find that the onset of superlattice growth in the drying drop is associated with the movement of a drying front across the surface of the droplet. We couple the rapid formation of large, highly ordered superlattices to the capillary-induced fluid flow. Further evaporation of interstitital solvent results in a slow contraction of the superlattice. The distribution of lattice parameters and tilt angles was significantly larger for superlattices prepared by fast evaporation compared to slow evaporation of the solvent.

  • 7.
    Kumar, Ankit
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Wetterskog, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Tai, Cheuk-Wai
    Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden.
    Akansel, Serkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Husain, Sajid
    Department of Physics, Indian Institute of Technology Delhi, New Delhi, India.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Brucas, Rimantas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Chaudhary, Sujeet
    Department of Physics, Indian Institute of Technology Delhi, New Delhi, India.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Effect of in situ electric-field-assisted growth on antiphase boundaries in epitaxial Fe3O4 thin films on MgO2018In: Physical Review Materials, ISSN 2475-9953, Vol. 2, no 5, article id 054407Article in journal (Refereed)
    Abstract [en]

    Antiphase boundaries (APBs) normally form as a consequence of the initial growth conditions in all spinel ferrite thin films. These boundaries result from the intrinsic nucleation and growth mechanism, and are observed as regions where the periodicity of the crystalline lattice is disrupted. The presence of APBs in epitaxial films of the inverse spinel Fe3O4 alters their electronic and magnetic properties due to strong antiferromagnetic (AF) interactions across these boundaries. We explore the effect of using in-plane in situ electric-field-assisted growth on the formation of APBs in heteroepitaxial Fe3O4(100)/MgO(100) thin films. The electric-field-assisted growth is found to reduce the AF interactions across APBs and, as a consequence, APB-free thin-film-like properties are obtained, which have been probed by electronic, magnetic, and structural characterization. The electric field plays a critical role in controlling the density of APBs during the nucleation process by providing an electrostatic force acting on adatoms and therefore changing their kinetics. This innovative technique can be employed to grow epitaxial spinel thin films with controlled AF interactions across APBs.

  • 8.
    Legaria, E. Polido
    et al.
    Swedish Univ Agr Sci SLU, Dept Mol Sci, Box 7015, S-75007 Uppsala, Sweden..
    Saldan, I.
    Swedish Univ Agr Sci SLU, Dept Mol Sci, Box 7015, S-75007 Uppsala, Sweden..
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Wetterskog, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Gunnarsson, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Kessler, V. G.
    Swedish Univ Agr Sci SLU, Dept Mol Sci, Box 7015, S-75007 Uppsala, Sweden..
    Seisenbaeva, G. A.
    Swedish Univ Agr Sci SLU, Dept Mol Sci, Box 7015, S-75007 Uppsala, Sweden..
    Coordination of rare earth element cations on the surface of silica-derived nanoadsorbents2018In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 47, no 4, p. 1312-1320Article in journal (Refereed)
    Abstract [en]

    Silica (SiO2)-derived nanoadsorbents are a powerful and attractive tool for the extraction and separation of rare earth elements (REE) from many perspectives such as reusability, efficiency and minimum impact on the environment. In the present work, we investigated two different methods of adsorption down to the molecular level: (1) the mechanism of the coordination of different groups of REE (light, medium, heavy) with iminodiacetic acid (IDA) was revealed by exploiting models obtained from X-ray crystallography, explaining the selectivity of this type of ligand, and (2) the mechanism of the seeding of RE(OH)(3) initiated by SiO2-based nanoadsorbents was investigated by EXAFS, both individually and in combination with mechanism (1), showing the coexistence of both mechanisms. The REE loaded nanoadsorbents possess a high magnetic susceptibility. This property was studied by magnetometry to quantify the REE adsorption efficiency and compared with the values obtained from complexometry.

  • 9. Ludwig, Frank
    et al.
    Kazakova, Olga
    Fernandez Barquin, Luis
    Fornara, Andrea
    Trahms, Lutz
    Steinhoff, Uwe
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Wetterskog, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Pankhurst, Quentin A.
    Southern, Paul
    Morales, Puerto
    Hansen, Mikkel Fougt
    Frandsen, Cathrine
    Olsson, Eva
    Gustafsson, Stefan
    Gehrke, Nicole
    Luedtke-Buzug, Kerstin
    Gruettner, Cordula
    Jonasson, Christian
    Johansson, Christer
    Magnetic, Structural, and Particle Size Analysis of Single- and Multi-Core Magnetic Nanoparticles2014In: IEEE transactions on magnetics, ISSN 0018-9464, E-ISSN 1941-0069, Vol. 50, no 11, article id 5300204Article in journal (Refereed)
    Abstract [en]

    We have measured and analyzed three different commercial magnetic nanoparticle systems, both multi-core and single-core in nature, with the particle (core) size ranging from 20 to 100 nm. Complementary analysis methods and same characterization techniques were carried out in different labs and the results are compared with each other. The presented results primarily focus on determining the particle size-both the hydrodynamic size and the individual magnetic core size-as well as magnetic and structural properties. The used analysis methods include transmission electron microscopy, static and dynamic magnetization measurements, and Mossbauer spectroscopy. We show that particle (hydrodynamic and core) size parameters can be determined from different analysis techniques and the individual analysis results agree reasonably well. However, in order to compare size parameters precisely determined from different methods and models, it is crucial to establish standardized analysis methods and models to extract reliable parameters from the data.

  • 10.
    Norrbo, Isabella
    et al.
    Univ Turku, Dept Chem, FI-20014 Turku, Finland;Univ Turku, Grad Sch UTUGS, Doctoral Programme Phys & Chem Sci PCS, FI-20014 Turku, Finland.
    Curutchet, Antton
    Univ Claude Bernard Lyon 1, Univ Lyon, ENS Lyon, CNRS,UMR 5182,Lab Chim, F-69342 Lyon, France.
    Kuusisto, Ari
    Solar Simulator Finland Ltd, FI-20660 Littoinen, Finland.
    Makela, Jaakko
    Univ Turku, Grad Sch UTUGS, Doctoral Programme Phys & Chem Sci PCS, FI-20014 Turku, Finland;Univ Turku, Dept Phys & Astron, FI-20014 Turku, Finland.
    Laukkanen, Pekka
    Univ Turku, Dept Phys & Astron, FI-20014 Turku, Finland.
    Paturi, Petriina
    Univ Turku, Dept Phys & Astron, Wihuri Phys Lab, FI-20014 Turku, Finland.
    Laihinen, Tero
    Univ Turku, Dept Chem, FI-20014 Turku, Finland.
    Sinkkonen, Jari
    Univ Turku, Dept Chem, FI-20014 Turku, Finland.
    Wetterskog, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mamedov, Fikret
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. Uppsala Univ, Dept Chem, SE-75120 Uppsala, Sweden.
    Le Bahers, Tangui
    Univ Claude Bernard Lyon 1, Univ Lyon, ENS Lyon, CNRS,UMR 5182,Lab Chim, F-69342 Lyon, France.
    Lastusaari, Mika
    Univ Turku, Dept Chem, FI-20014 Turku, Finland;Turku Univ, Ctr Mat & Surfaces MatSurf, FI-20014 Turku, Finland.
    Solar UV index and UV dose determination with photochromic hackmanites: from the assessment of the fundamental properties to the device2018In: Materials Horizons, ISSN 2051-6347, E-ISSN 2051-6355, Vol. 5, no 3, p. 569-576Article in journal (Refereed)
    Abstract [en]

    Extended exposure to sunlight or artificial UV sources is a major cause of serious skin and eye diseases such as cancer. There is thus a great need for convenient materials for the easy monitoring of UV doses. While organic photochromic molecules are tunable for responses under different wavelengths of UV radiation, they suffer from rather poor durability because the color changes involve drastic changes in molecular structure. Inorganic materials, on the other hand, are durable, but they have lacked tunability. Here, by combining computational and empirical data, we confirm the mechanism of coloration in the hackmanites, nature-based materials, and introduce a new technique called thermotenebrescence. With knowledge of the mechanism, we show that we can control and thus tune the energy of electronic states of synthetic hackmanites (Na,M)(8)Al6Si6O24(Cl,S)(2) so that their body color is sensitive to the solar UV index as well as UVA, UVB or UVC radiation levels. Finally, we demonstrate that it is possible to use images taken with an inexpensive cell phone to quantify the radiation dose or UV index. The hackmanite materials thus show great potential for use in portable healthcare both in everyday life and in laboratories.

  • 11.
    Tian, Bo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Han, Yuanyuan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wetterskog, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Donolato, Marco
    BluSense Diagnostics, Copenhagen, Denmark.
    Fougt Hansen, Mikkel
    Technical University of Denmark.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Strömberg, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    MicroRNA Detection through DNAzyme-Mediated Disintegration of Magnetic Nanoparticle Assemblies2018In: ACS Sensors, ISSN 2379-3694, Vol. 3, p. 1884-1891Article in journal (Refereed)
    Abstract [en]

    DNA-assembled nanoparticle superstructures offer numerous bioresponsive properties that can be utilized for point-of-care diagnostics. Functional DNA sequences such as deoxyribozymes (DNAzymes) provide novel bioresponsive strategies and further extend the application of DNA-assembled nanoparticle superstructures. In this work, we describe a microRNA detection biosensor that combines magnetic nanoparticle (MNP) assemblies with DNAzyme-assisted target recycling. The DNA scaffolds of the MNP assemblies contain substrate sequences for DNAzyme and can form cleavage catalytic structures in the presence of target DNA or RNA sequences, leading to rupture of the scaffolds and disintegration of the MNP assemblies. The target sequences are preserved during the cleavage reaction and release into the suspension to trigger the digestion of multiple DNA scaffolds. The high local concentration of substrate sequences in the MNP assemblies reduces the diffusion time for target recycling. The concentration of released MNPs, which is proportional to the concentration of the target, can be quantified by a 405 nm laser-based optomagnetic sensor. For the detection of let-7b in 10% serum, after 1 h of isothermal reaction at 50 degrees C, we found a linear detection range between 10 pM and 100 nM with a limit of detection of 6 pM. For the quantification of DNA target in buffer solution, a limit of detection of 1.5 pM was achieved. Compared to protein enzyme-based microRNA detection methods, the proposed DNAzyme-based biosensor has an increased stability, a reduced cost and a possibility to be used in living cells, all of which are valuable features for biosensing applications.

  • 12.
    Tian, Bo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Liao, Xiaoqi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Strömberg, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Wetterskog, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Ferromagnetic Resonance Biosensor for Homogeneous and Volumetric Detection of DNA2018In: ACS Sensors, ISSN 2379-3694, Vol. 3, no 6, p. 1093-1101Article in journal (Refereed)
    Abstract [en]

    The ability to detect and analyze the state ofmagnetic labels with high sensitivity is of crucial importance fordeveloping magnetic biosensors. In this work, we demonstrate, forthefirst time, a ferromagnetic resonance (FMR) basedhomogeneous and volumetric biosensor for magnetic labeldetection. Two different isothermal amplification methods, i.e.,rolling circle amplification (RCA) and loop-mediated isothermalamplification (LAMP), are adopted and combined with a standardelectron paramagnetic resonance (EPR) spectrometer for FMRbiosensing. For the RCA-based FMR biosensor, binding of RCAproducts of a syntheticVibrio choleraetarget DNA sequence givesrise to the formation of aggregates of magnetic nanoparticles.Immobilization of nanoparticles within the aggregates leads to adecrease of the net anisotropy of the system and a concomitant increase of the resonancefield. A limit of detection of 1 pM isobtained with a linear detection range between 7.8 and 250 pM. For the LAMP-based sensing, a synthetic Zika virus targetoligonucleotide is amplified and detected in 20% serum samples. Immobilization of magnetic nanoparticles is induced by theircoprecipitation with Mg2P2O7(a byproduct of LAMP) and provides a detection sensitivity of 100 aM. The fast measurement,high sensitivity, and miniaturization potential of the proposed FMR biosensing technology makes it a promising candidate fordesigning future point-of-care devices.

  • 13.
    Tian, Bo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Strömberg, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Wetterskog, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Ferromagnetic resonance biosensor for homogeneous and volumetric detection of DNA2018Conference paper (Refereed)
  • 14.
    Tian, Bo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Wetterskog, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Qiu, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Zardán Gómez de la Torre, Teresa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Donolato, Marco
    BluSense Diagnostics, Copenhagen, Denmark.
    Fougt Hansen, Mikkel
    Technical University of Denmark.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Strömberg, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Shape anisotropy enhanced optomagnetic measurement for prostate-specific antigen detection via magnetic chain formation2017In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 98, p. 285-291Article in journal (Refereed)
    Abstract [en]

    We demonstrate a homogeneous biosensor for the detection of multivalent targets by combination of magnetic nanoparticle (MNP) chains and a low-cost 405 nm laser-based optomagnetic system. The MNP chains are assembled in a rotating magnetic field and stabilized by multivalent target molecules. The number of chains remaining in zero field is proportional to the target concentration, and can be quantified by optomagnetic measurements. The shape anisotropy of the MNP chains enhances the biosensor system in terms of providing efficient mixing, reduction of depletion effects (via magnetic shape anisotropy), and directly increasing the optomagnetic signal (via optical shape anisotropy). We achieve a limit of detection (LOD) of 5.5 pM (0.82 ng/mL) for the detection of a model multivalent molecule, biotinylated anti-streptavidin, in PBS. For the measurements of prostate-specific antigen (PSA) in 50% serum using the proposed method, we achieve an LOD of 21.6 pM (0.65 ng/mL) and a dynamic detection range up to 66.7 nM (2 µg/mL) with a sample-to-result time of approximately 20 min. The performance for PSA detection therefore well meets the clinical requirements in terms of LOD (the threshold PSA level in blood is 4 ng/mL) and detection range (PSA levels span from < 0.1–104 ng/mL in blood), thus showing great promise for routine PSA diagnostics and for other in-situ applications.

  • 15.
    Wetterskog, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Agthe, Michael
    Mayence, Arnaud
    Grins, Jekabs
    Wang, Dong
    Rana, Subhasis
    Ahniyaz, Anwar
    Salazar-Alvarez, German
    Bergstrom, Lennart
    Precise control over shape and size of iron oxide nanocrystals suitable for assembly into ordered particle arrays2014In: Science and Technology of Advanced Materials, ISSN 1468-6996, E-ISSN 1878-5514, Vol. 15, no 5, p. 055010-Article in journal (Refereed)
    Abstract [en]

    Here we demonstrate how monodisperse iron oxide nanocubes and nanospheres with average sizes between 5 and 27 nm can be synthesized by thermal decomposition. The relative importance of the purity of the reactants, the ratio of oleic acid and sodium oleate, the maximum temperature, and the rate of temperature increase, on robust and reproducible size and shape-selective iron oxide nanoparticle synthesis are identified and discussed. The synthesis conditions that generate highly monodisperse iron oxide nanocubes suitable for producing large ordered arrays, or mesocrystals are described in detail.

  • 16.
    Wetterskog, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Castro, A.
    SOLVE Res & Consultancy AB, Lund, Sweden..
    Zeng, L.
    Chalmers, Dept Appl Phys, Gothenburg, Sweden..
    Petronis, S.
    SP Tech Res Inst Sweden, SP Chem Mat & Surfaces, Boras, Sweden..
    Heinke, D.
    nanoPET Pharma GmbH, Berlin, Germany..
    Olsson, E.
    Chalmers, Dept Appl Phys, Gothenburg, Sweden..
    Nilsson, L.
    SOLVE Res & Consultancy AB, Lund, Sweden.;Lund Univ, Lund Ctr Field Flow Fractionat, Dept Food Technol Engn & Nutr, Lund, Sweden..
    Gehrke, N.
    nanoPET Pharma GmbH, Berlin, Germany..
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Size and property bimodality in magnetic nanoparticle dispersions: single domain particles vs. strongly coupled nanoclusters2017In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, no 12, p. 4227-4235Article in journal (Refereed)
    Abstract [en]

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

  • 17.
    Wetterskog, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Jonasson, Christian
    RISE Acreo, S-40014 Gothenburg, Sweden..
    Smilgies, Detlef-M.
    Cornell Univ, Cornell High Energy Synchrotron Source, Ithaca, NY 14853 USA..
    Schaller, Vincent
    Chalmers Ind Tekn, S-41288 Gothenburg, Sweden..
    Johansson, Christer
    RISE Acreo, S-40014 Gothenburg, Sweden..
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Colossal Anisotropy of the Dynamic Magnetic Susceptibility in Low-Dimensional Nanocube Assemblies2018In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, no 2, p. 1403-1412Article in journal (Refereed)
    Abstract [en]

    One of the ultimate goals of nanocrystal self-assembly is to transform nanoscale building blocks into a material that displays enhanced properties relative to the sum of its parts. Herein, we demonstrate that 1D needle shaped assemblies composed of Fe3-delta O4 nanocubes display a significant augmentation of the magnetic susceptibility and dissipation as compared to OD and 2D systems. The performance of the nanocube needles is highlighted by a colossal anisotropy factor defined as the ratio of the parallel to the perpendicular magnetization components. We show that the origin of this effect cannot be ascribed to shape anisotropy in its classical sense; as such, it has no analogy in bulk magnetic materials. The temperature-dependent anisotropy factors of the in- and out-of-phase components of the magnetization have an extremely strong particle size dependence and reach values of 80 and 2500, respectively, for the largest nanocubes in this study. Aided by simulations, we ascribe the anisotropy of the magnetic susceptibility, and its strong particle-size dependence to a synergistic coupling between the dipolar interaction field and a net anisotropy field resulting from a partial texture in the 1D nanocube needles.

1 - 17 of 17
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