TY - JOUR A1 - Thünemann, Andreas A1 - Kubowicz, S. A1 - v. Berlepsch, H. A1 - Möhwald, H. T1 - Two-Compartment Micellar Assemblies Obtained via Aqueous Self-Organization of Synthetic Polymer Building Blocks N2 - We synthesized a symmetric linear ABCBA pentablock copolymer consisting of poly(ethylene oxide), poly(-benzyl L-glutamate), and a poly(perfluoro ether) (fluorolink). The different blocks are highly immiscible with each other and form two-compartment micelles of mainly cylindrical shape in aqueous solution with lengths in the range of 100 to 200 nm and diameters of about 24 nm. The poly(perfluoro ether) (C blocks) forms the liquidlike center of the micelles (d = 6 nm). This is surrounded by a first shell of ca. 2 nm thickness consisting of -sheets of poly(-benzyl L-glutamate) (B blocks) and a second 7 nm shell of poly(ethylene oxide) (A blocks). The A blocks provide water solubility, and the B and C blocks form separated hydrophobic compartments. This work is a contribution to the development of multicompartment micelles devoted to mimic transport proteins such as serum albumins in long-term development. KW - Micelles KW - Block-copolymers PY - 2006 DO - https://doi.org/10.1021/la0533720 SN - 0743-7463 SN - 1520-5827 VL - 22 IS - 6 SP - 2506 EP - 2510 PB - American Chemical Society CY - Washington, DC AN - OPUS4-12190 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 - JOUR A1 - Kubowicz, S. A1 - Thünemann, Andreas A1 - Weberskirch, R. A1 - Möhwald, H. T1 - Cylindrical Micelles of alpha-Fluorocarbon-omega-Hydrocarbon End-Capped Poly(N-acylethylene imine)s N2 - Micelles of ABC block copolymers with varying degrees of polymerization of the B block (n) and constant lengths of the A and C blocks were investigated by small-angle X-ray scattering (SAXS), analytical ultracentrifugation (AUC), surface tension measurements, and isothermal titration calorimetry. The copolymers consisting of hydrophilic poly(N-acylethylene imine)s, end-capped with a hydrophobic fluorocarbon and a hydrocarbon block, are polymeric surfactants ( = 35 mN/m). They form cylindrical micelles with radii of 3.0 nm (n = 35), 3.8 nm (n = 57), and 4.0 nm (n = 72). Their lengths are about 20 nm. The micelles can be doped with 1,4-diiodoperfluorobutane for the polymers with n = 57 and 72 but not for n = 35. We assume that the doped micelles form distinct fluorocarbon domains, which are able to incorporate selectively the fluorocarbon dopant. The work presented here is a contribution to the development of multicompartment micelles. KW - Micelles KW - Small-angle X-ray scattering PY - 2005 DO - https://doi.org/10.1021/la050987o SN - 0743-7463 SN - 1520-5827 VL - 21 IS - 16 SP - 7214 EP - 7219 PB - American Chemical Society CY - Washington, DC AN - OPUS4-10380 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weiss, S. I. A1 - Sieverling, N. A1 - Niclasen, M. A1 - Maucksch, Ch. A1 - Thünemann, Andreas A1 - Möhwald, H. A1 - Reinhardt, D. A1 - Rosenecker, J. A1 - Rudolph, C. T1 - Uronic acids functionalized polyethyleneimine (PEI)-polyethyleneglycol (PEG)-graft-copolymers as novel synthetic gene carriers N2 - In this study, we investigated galacturonic (GalAc)- and mannuronic (ManAc) acids as novel targeting ligands for receptor-mediated gene delivery. GalAc and ManAc were coupled to either polyethyleneimine (PEI) or PEI–polyethyleneglycol (PEG). Furthermore, lactobionic acid (LacAc), which comprises a GalAc-related carbohydrate ring, was coupled to each of the polymers through its open-chain gluconic acid moiety. The molar mass distributions of the polymers were characterized by analytical ultracentrifugation and size exclusion chromatography. PEI-conjugate–pDNA complexes were transfected into HepG2-, HeLa-, and 16HBE14o--cells. Gene expression mediated by GalAc- and LacAc-functionalized PEI-conjugates was lower than for PEI. In contrast, gene expression mediated by ManAc-functionalized PEI-conjugates was up to three orders of magnitude higher than for the other tested PEI-conjugates, in particular for negatively charged gene vectors at low N/P ratios, independent of the cell line. Pre-incubation of cells with an excess of ManAc before transfection significantly inhibited transfection rates only for ManAc-functionalized PEI-conjugates. Coupling of methyl-α-D-mannuronic acid to PEI resulted in significantly lower transfection rates than for ManAc-PEI based complexes. Together with fluorescence microscopy images of fluorescein-labelled ManAc-functionalized dextrans and FACS analyses of cells, these results demonstrate that receptor-mediated endocytosis of ManAc–PEI-conjugate–pDNA complexes via ManAc-specific receptors was involved in gene transfer. In conclusion, ManAc-modification of PEI-polymers represents a novel strategy for receptor-mediated gene delivery which could be promising for in vivo application. KW - Gene therapy KW - Gene transfer KW - Polyethylene oxide KW - Nanoparticle PY - 2006 DO - https://doi.org/10.1016/j.biomaterials.2005.11.011 SN - 0142-9612 VL - 27 IS - 10 SP - 2302 EP - 2312 PB - Elsevier CY - Oxford AN - OPUS4-11678 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rocha, S. A1 - Krastev, R. A1 - Thünemann, Andreas A1 - Carmo Pereira, M. A1 - Möhwald, H. A1 - Brezesinski, G. T1 - Adsorption of Amyloid beta-Peptide at Polymer Surfaces: A Neutron Reflectivity Study KW - Beta amyloid KW - Neutron reflectivity PY - 2005 SN - 1439-4235 SN - 1439-7641 IS - 6 SP - 2527 EP - 2534 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-11562 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 DO - 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 - Rocha, S. A1 - Thünemann, Andreas A1 - do Carmo Pereira, M. A1 - Coelho, M. A1 - Möhwald, H. A1 - Brezesinski, G. T1 - Influence of fluorinated and hydrogenated nanoparticles on the structure and fibrillogenesis of amyloid beta-peptide N2 - Peptide aggregation in amyloid fibrils is implicated in the pathogenesis of several diseases such as Alzheimer's disease. There is a strong correlation between amyloid fibril formation and a decrease in conformational stability of the native state. Amyloid-β peptide (Aβ), the aggregating peptide in Alzheimer's disease, is natively unfolded. The deposits found in Alzheimer's disease are composed of Aβ fibrillar aggregates rich in β-sheet structure. The influence of fluorinated complexes on the secondary structure and fibrillogenesis of Aβ peptide was studied by circular dichroism (CD) spectroscopy and transmission electron microscopy (TEM). CD spectra show that complexes of polyampholyte and fluorinated dodecanoic acid induce a-helix structure in Aβ, but their hydrogenated analogous lead to β-sheet formation and aggregation. The fluorinated nanoparticles with highly negative zeta potential and hydrophobic fluorinated core have the fundamental characteristics to prevent Aβ fibrillogenesis. KW - Amyloid beta-peptide KW - Circular dichroism KW - Conformation analysis KW - Electron microscopy KW - Fluorinated complexes KW - Nanoparticles PY - 2008 DO - https://doi.org/10.1016/j.bpc.2008.06.010 SN - 0301-4622 SN - 1873-4200 VL - 137 IS - 1 SP - 35 EP - 42 PB - Elsevier CY - Amsterdam AN - OPUS4-17810 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rocha, S. A1 - Thünemann, Andreas A1 - Pereira, M.C. A1 - Coelho, M.A.N. A1 - Möhwald, H. A1 - Brezesinski, G. T1 - The Conformation of B18 Peptide in the Presence of Fluorinated and Alkylated Nanoparticles KW - Small-angle-X-ray scattering KW - Circular dichroism PY - 2005 SN - 1439-4227 SN - 1439-7633 VL - 6 SP - 1 EP - 4 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-6064 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -