TY - JOUR A1 - Thünemann, Andreas A1 - Schütt, D. A1 - Kaufner, L. A1 - Pison, U. A1 - Möhwald, H. T1 - Maghemite Nanoparticles Protectively Coated with Poly(ethylene imine) and Poly(ethylene oxide)-block-poly(glutamic acid) N2 - Superparamagnetic iron oxide particles (SPIO) of maghemite were prepared in aqueous solution and subsequently stabilized with polymers in two layer-by-layer deposition steps. The first layer around the maghemite core is formed by poly(ethylene imine) (PEI), and the second one is formed by poly(ethylene oxide)-block-poly(glutamic acid) (PEO-PGA). The hydrodynamic diameter of the particles increases stepwise from Dh = 25 nm (parent) via 35 nm (PEI) to 46 nm (PEI plus PEO-PGA) due to stabilization. This is accompanied by a switching of their -potentials from moderately positive (+28 mV) to highly positive (+50 mV) and finally slightly negative (-3 mV). By contrast, the polydispersity indexes of the particles remain constant (ca. 0.15). Mössbauer spectroscopy revealed that the iron oxide, which forms the core of the particles, is only present as Fe(III) in the form of superparamagnetic maghemite nanocrystals. The magnetic domains and the maghemite crystallites were found to be identical with a size of 12.0 ± 0.5 nm. The coated maghemite nanoparticles were tested to be stable in water and in physiological salt solution for longer than 6 months. In contrast to novel methods for magnetic nanoparticle production, where organic solvents are necessary, the procedure proposed here can dispense with organic solvents. Magnetic resonance imaging (MRI) experiments on living rats indicate that the nanoparticles are useful as an MRI contrast agent. KW - Polymer KW - Polyelectrolyte KW - Mössbauer PY - 2006 U6 - https://doi.org/10.1021/la052990d SN - 0743-7463 SN - 1520-5827 VL - 22 IS - 5 SP - 2351 EP - 2357 PB - American Chemical Society CY - Washington, DC AN - OPUS4-12119 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thünemann, Andreas A1 - Schütt, D. A1 - Sachse, R. A1 - Schlaad, H. A1 - Möhwald, H. T1 - Complexes of Poly(ethylene oxide)-block-Poly(L-glutamate) and Diminazene KW - Polymers KW - Nanoparticles KW - Proteins PY - 2006 SN - 0743-7463 SN - 1520-5827 VL - 22 IS - 5 SP - 2323 EP - 2328 PB - American Chemical Society CY - Washington, DC AN - OPUS4-12117 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schütt, D. A1 - Thünemann, Andreas T1 - Nanopartikel aus PEO-Polyglutaminsäure für die medizinische Anwendung T2 - Workshop des Kompetenznetzwerks Bioaktive Oberflächen, Technische Universität Berlin (Inst. f. Werkstoffwissenschaften und -technologien) CY - Berlin, Germany DA - 2005-11-18 PY - 2005 AN - OPUS4-11514 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schütt, D. A1 - Jentzen, V. A1 - Thünemann, Andreas A1 - Möhwald, H. T1 - Nanocarrier for Medical Applications T2 - Fachtagung des Max-Planck-Instituts für Kolloid- und Grenzflächenforschung und des Fraunhofer Instituts für Angewandte Polymerforschung, Surfactant-directed Complex Formation in Supramolecular Chemistry CY - Potsdam, Germany DA - 2004-01-09 PY - 2004 AN - OPUS4-4991 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -