Physical characterization of iron oxide nanoparticles in magnetoferritin L. Melnikova 1, Z. Mitroova 1, M. Timko 1, J. Kovac 1, M. Koralewski 2, M. Pochylski 2, M.V. Avdeev 3, V.I. Petrenko 3,4, V.M. Garamus 5, L. Almasy 6, P. Kopcansky 1 1 Institute of Experimental Physics, SAS, Watsonova 47, Kosice, Slovakia 2 Faculty of Physics, Adam Mickiewicz University, Umultowska 85, Poznań, Poland 3 Frank Laboratory of Neutron Physcis, Joint Institute for Nuclear Research, Dubna, Russia 4 Taras Shevchenko National University of Kyiv, Kyiv, Ukraine 5 Helmholtz-Zentrum Geesthacht, Zentrum für Material- und Küstenforschung, Geesthacht, Germany 6 Wigner Research Centre for Physics, Institute for Solid State Physics and Optics. H-1525, Budapest, P. O. Box 49, Hungary 3Fe (CH 3 ) 3 NO + 4H 2 O → Fe 3 O 4 + 2(CH 3 ) 3 N + 6H + + H 2 O 2  Magnetic protein  Iron core contains magnetic nanoparticles (Fe 3 O 4, γ−Fe 2 O 3 ) surrounded by a protein shell (apoferritin)  minimized problem of toxicity and of side effects of magnetic nanoparticles in biological systems  targeted transport of anti-cancer drugs in biomedicine  contrast medium in radiodiagnostic magnetic resonance imaging  imunomagnetic labeling of cells in molecular biology  magnetic separation techniques of cell cultures in biotechnology  nanodimensional material for catalytic chemistry  model system for mathematical simulations  study of structure and composition of iron core of magnetoferritin in relationship to neurodegenerative diseases in biophysics INTRODUCTION Fig. 5. Comparison of the reduced magnetic birefringence as a function of the square of the applied magnetic field for suspensions of ferritin, mixture of ferritin and magnetite (Fe weight proportion – 23:1), magnetoferritin, and nanoscale magnetite. RESULTS CONCLUSIONS 1.F. C. Meldrum, B.R. Heywood and S.Mann, Science 257, 522 (1992) 2.J. Galazka – Friedman, Hyper. Inter. 182, 31 (2008) 3.M. Koralewski, M. Pochylski, Z. Mitroova, M. Timko, P. Kopcansky, L. Melnikova, J. Magn. Magn. Mater. 323, 2413 (2011) 4.M. Koralewski, J.W. Kłos, M. Baranowski, Z. Mitroova, P. Kopcansky, L. Melnikova, M. Okuda, W. Schwarzacher. Nanotechnology, vol. 23 (2012) pp  Presence of superparamagnetic nanoparticles with diameter of about 5 nm are confined in the spherical protein shell.  Differences in magnetically induced optical birefringence measurements allow discrimination between a ferrihydrite or magnetite/maghemite core in synthetic magnetoferritin or biogenic ferritin, which could be a very useful in biomedicine. ACKNOWLEDGEMENTS: This work was supported from the Ministry of Science and Higher Education, within grant No N N , from the European Community's Seventh Framework Programme (FP7/ and Grant Agreement N , NMI3), the Projects No and in the frame of Structural Funds of European Union, Centre of Excellence of SAS Nanofluid and VEGA 0077 as well as APVV The work was based on experiments performed at the Swiss spallation neutron source SINQ, Paul Scherrer Institute and the Grenoble High Magnetic Field Laboratory CNRS. REFERENCES ~ 12 nm Chemical synthesis at 65°C and anaerobic alkaline conditions 1.transition of ferrous ions through the apoferritin 2.oxidation of iron ions 3.formation of magnetoferritin (magnetite inside the apoferritin) Fig. 2 Field dependence of magnetoferritin magnetization measured at room temperature using SQUID magnetometer shows superparamagnetic behavior of nanoparticles Fig. 3. Size distribution of apoferritin and magnetoferritin aqueous suspension shows, that hydrodynamic diameter is higher in case of magnetoferritin considering the thickness of electric double layer, surrounding molecules in solution. Fig. 1. TEM image of magnetoferritin shows magnetic nanocrystallites with diameter of 5 nm PropertyFerritinMagnetiteMagnetoferritin nsns -1,2 x ,69 x C CM ( mA -2 )6,973,62 x ,45 x 10 4  m (  B )( )20,690/19, /1125 Table. Obtained values of the saturation magnetic birefingence, Cotton-Mouton constant and magnetic moment of magnetic nanoparticles of different kind of disperions Fig. 4. The minima and maxima characteristic to apoferritin due to its almost ideal form of spherical shell are preserved. The spherical form of the protein is partly preserved for the case of magnetoferritin and the pronounced scattering at small q values shows aggregation of sizes larger than 200 nm.