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Baranchikov AE, Kopitsa GP, Yorov KE, Sipyagina NA, Lermontov SA, Pavlova AA, Kottsov SY, Garamus VM, Ryukhtin V, Ivanov VK. SiO2–TiO2 Binary Aerogels: A Small-Angle Scattering Study. RUSS J INORG CHEM+ 2021. [DOI: 10.1134/s003602362106005x] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Vasilescu C, Latikka M, Knudsen KD, Garamus VM, Socoliuc V, Turcu R, Tombácz E, Susan-Resiga D, Ras RHA, Vékás L. High concentration aqueous magnetic fluids: structure, colloidal stability, magnetic and flow properties. Soft Matter 2018; 14:6648-6666. [PMID: 30035279 DOI: 10.1039/c7sm02417g] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
This paper is an in-depth analysis devoted to two basic types of water based magnetic fluids (MFs), containing magnetite nanoparticles with electrostatic and with electro-steric stabilization, both obtained by chemical coprecipitation synthesis under atmospheric conditions. The two sets of magnetic fluid samples, one with citric acid (MF/CA) and the other with oleic acid (MF/OA) coated magnetic nanoparticles, respectively, achieved saturation magnetization values of 78.20 kA m-1 for the electrostatically and 48.73 kA m-1 for the electro-sterically stabilized aqueous ferrofluids which are among the highest reported to date. A comprehensive comparative analysis combining electron microscopy, X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy, vibrating sample magnetometry, small-angle X-ray and neutron scattering, dynamic light scattering and magneto-rheometry revealed similarities and essential differences on the microscopic and macroscopic level between the two kinds of water-based ferrofluids. While the saturation magnetization values are quite different, the hydrodynamic volume fractions of the highest concentration MF/CA and MF/OA samples are practically the same, due to the significantly different thicknesses of the particles' coating layers. The results of volume fraction dependent structure analyses over a large concentration range by small-angle X-ray and neutron scattering, correlated with magneto-rheological investigations for the electrostatically stabilized MFs, demonstrate formation of short chains of magnetic nanoparticles which are relatively stable against coagulation with increasing concentration, while for MFs with electro-steric stabilization, magnetic field and shear rate dependent loosely bound structures are observed. These particle structures in MF/OA samples manifest themselves already at low volume fraction values, which can be attributed mainly to magnetic interactions of larger size particles, besides non-magnetic interactions mediated by excess surfactant.
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Affiliation(s)
- Corina Vasilescu
- Department of Applied Chemistry and Organic and Natural Compounds Engineering, Faculty of Industrial Chemistry and Environmental Engineering, Politehnica University Timisoara, Carol Telbisz 6, 300001 Timişoara, Romania
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Balejčíková L, Garamus VM, Avdeev MV, Petrenko VI, Almásy L, Kopčanský P. The effect of solution pH on the structural stability of magnetoferritin. Colloids Surf B Biointerfaces 2017; 156:375-381. [PMID: 28551571 DOI: 10.1016/j.colsurfb.2017.05.036] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 05/06/2017] [Accepted: 05/12/2017] [Indexed: 11/29/2022]
Abstract
The structural stability of magnetoferritin, a synthetic analogue of ferritin, at various pH levels is assessed here. The structural and electrical properties of the complexes were determined by small-angle X-ray scattering (SAXS), dynamic light scattering (DLS) and zeta potential measurements. At pH 3-6 a reduction of electrostatic repulsion on the suspended colloids resulted in aggregation and sedimentation of magnetoferritin. At neutral to slightly alkaline conditions (pH 7-9) the magnetoferritin structure was stable for lower iron loadings. Higher solution pH 10-12 induced destabilization of the protein structure and dissociation of subunits. Increasing the loading factor in the MFer complex leads to decrease of the stability versus pH changes.
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Affiliation(s)
- L Balejčíková
- Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 04001 Košice, Slovakia.
| | - V M Garamus
- Helmholtz-Zentrum Geesthacht, Centre for Materials and Coastal Research, Max-Planck-Street 1, 21502 Geesthacht, Germany
| | - M V Avdeev
- Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow Region, Russia
| | - V I Petrenko
- Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow Region, Russia; Kyiv Taras Shevchenko National University, Volodymyrska Street 64, Kyiv 01033, Ukraine
| | - L Almásy
- State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010, China; Wigner Research Centre for Physics, Hungarian Academy of Sciences, H-1525, Budapest POB 49, Hungary
| | - P Kopčanský
- Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 04001 Košice, Slovakia
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Wieland DCF, Zander T, Garamus VM, Krywka C, Dedinaite A, Claesson P, Willumeit-Römer R. Complex solutions under shear and pressure: a rheometer setup for X-ray scattering experiments. J Synchrotron Radiat 2017; 24:646-652. [PMID: 28452756 DOI: 10.1107/s1600577517002648] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 02/15/2017] [Indexed: 06/07/2023]
Abstract
A newly developed high-pressure rheometer for in situ X-ray scattering experiments is described. A commercial rheometer was modified in such a way that X-ray scattering experiments can be performed under different pressures and shear. First experiments were carried out on hyaluronan, a ubiquitous biopolymer that is important for different functions in the body such as articular joint lubrication. The data hint at a decreased electrostatic interaction at higher pressure, presumably due to the increase of the dielectric constant of water by 3% and the decrease of the free volume at 300 bar.
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Affiliation(s)
- D C F Wieland
- Institute for Materials Research, Helmholtz Zentrum Geesthacht, Max-Planck-Strasse 1, Geesthacht 21502, Germany
| | - T Zander
- Institute for Materials Research, Helmholtz Zentrum Geesthacht, Max-Planck-Strasse 1, Geesthacht 21502, Germany
| | - V M Garamus
- Institute for Materials Research, Helmholtz Zentrum Geesthacht, Max-Planck-Strasse 1, Geesthacht 21502, Germany
| | - C Krywka
- Institute for Materials Research, Helmholtz Zentrum Geesthacht, Max-Planck-Strasse 1, Geesthacht 21502, Germany
| | - A Dedinaite
- Department of Chemistry, Surface and Corrosion Science, KTH Royal Institute of Technology, Drottning Kristinas väg 51, Stockholm 10044, Sweden
| | - P Claesson
- Department of Chemistry, Surface and Corrosion Science, KTH Royal Institute of Technology, Drottning Kristinas väg 51, Stockholm 10044, Sweden
| | - R Willumeit-Römer
- Institute for Materials Research, Helmholtz Zentrum Geesthacht, Max-Planck-Strasse 1, Geesthacht 21502, Germany
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von Gundlach AR, Garamus VM, Willey TM, Ilavsky J, Hilpert K, Rosenhahn A. Use of small-angle X-ray scattering to resolve intracellular structure changes of Escherichia coli cells induced by antibiotic treatment. J Appl Crystallogr 2016; 49:2210-2216. [PMID: 27980516 PMCID: PMC5139998 DOI: 10.1107/s1600576716018562] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 11/19/2016] [Indexed: 12/22/2022] Open
Abstract
The application of small-angle X-ray scattering (SAXS) to whole Escherichia coli cells is challenging owing to the variety of internal constituents. To resolve their contributions, the outer shape was captured by ultra-small-angle X-ray scattering and combined with the internal structure resolved by SAXS. Building on these data, a model for the major structural components of E. coli was developed. It was possible to deduce information on the occupied volume, occurrence and average size of the most important intracellular constituents: ribosomes, DNA and proteins. E. coli was studied after treatment with three different antibiotic agents (chloramphenicol, tetracycline and rifampicin) and the impact on the intracellular constituents was monitored.
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Affiliation(s)
- A. R. von Gundlach
- Analytical Chemistry – Biointerfaces, Ruhr-University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | - V. M. Garamus
- Helmholtz-Zentrum Geesthacht, Zentrum für Material- und Küstenforschung GmbH, Max-Planck-Strasse 1, 21502 Geesthacht, Germany
| | - T. M. Willey
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - J. Ilavsky
- X-ray Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, USA
| | - K. Hilpert
- Institute of Infection and Immunity, St George’s University of London (SGUL), Cranmer Terrace, London SW17 0RE, UK
| | - A. Rosenhahn
- Analytical Chemistry – Biointerfaces, Ruhr-University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
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Wieland DCF, Garamus VM, Zander T, Krywka C, Wang M, Dedinaite A, Claesson PM, Willumeit-Römer R. Studying solutions at high shear rates: a dedicated microfluidics setup. J Synchrotron Radiat 2016; 23:480-486. [PMID: 26917136 DOI: 10.1107/s1600577515024856] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 12/28/2015] [Indexed: 06/05/2023]
Abstract
The development of a dedicated small-angle X-ray scattering setup for the investigation of complex fluids at different controlled shear conditions is reported. The setup utilizes a microfluidics chip with a narrowing channel. As a consequence, a shear gradient is generated within the channel and the effect of shear rate on structure and interactions is mapped spatially. In a first experiment small-angle X-ray scattering is utilized to investigate highly concentrated protein solutions up to a shear rate of 300000 s(-1). These data demonstrate that equilibrium clusters of lysozyme are destabilized at high shear rates.
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Affiliation(s)
- D C F Wieland
- Institute for Materials Research, Helmholtz-Zentrum Geestacht: Centre for Materials and Coast Research, Max-Planck-Strasse 1, Geesthacht 21502, Germany
| | - V M Garamus
- Institute for Materials Research, Helmholtz-Zentrum Geestacht: Centre for Materials and Coast Research, Max-Planck-Strasse 1, Geesthacht 21502, Germany
| | - T Zander
- Institute for Materials Research, Helmholtz-Zentrum Geestacht: Centre for Materials and Coast Research, Max-Planck-Strasse 1, Geesthacht 21502, Germany
| | - C Krywka
- Institute for Materials Research, Helmholtz-Zentrum Geestacht: Centre for Materials and Coast Research, Max-Planck-Strasse 1, Geesthacht 21502, Germany
| | - M Wang
- Department of Chemistry, Surface and Corrosion Science, KTH Royal Institute of Technology, Drottning Kristinas väg 51, Stockholm 10044, Sweden
| | - A Dedinaite
- Department of Chemistry, Surface and Corrosion Science, KTH Royal Institute of Technology, Drottning Kristinas väg 51, Stockholm 10044, Sweden
| | - P M Claesson
- Department of Chemistry, Surface and Corrosion Science, KTH Royal Institute of Technology, Drottning Kristinas väg 51, Stockholm 10044, Sweden
| | - R Willumeit-Römer
- Institute for Materials Research, Helmholtz-Zentrum Geestacht: Centre for Materials and Coast Research, Max-Planck-Strasse 1, Geesthacht 21502, Germany
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von Gundlach AR, Garamus VM, Gorniak T, Davies HA, Reischl M, Mikut R, Hilpert K, Rosenhahn A. Small angle X-ray scattering as a high-throughput method to classify antimicrobial modes of action. Biochim Biophys Acta 2015; 1858:918-25. [PMID: 26730877 DOI: 10.1016/j.bbamem.2015.12.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 12/17/2015] [Accepted: 12/20/2015] [Indexed: 10/22/2022]
Abstract
Multi-drug resistant bacteria are currently undermining our health care system worldwide. While novel antimicrobial drugs, such as antimicrobial peptides, are urgently needed, identification of new modes of action is money and time consuming, and in addition current approaches are not available in a high throughput manner. Here we explore how small angle X-ray scattering (SAXS) as high throughput method can contribute to classify the mode of action for novel antimicrobials and therefore supports fast decision making in drug development. Using data bases for natural occurring antimicrobial peptides or predicting novel artificial peptides, many candidates can be discovered that will kill a selected target bacterium. However, in order to narrow down the selection it is important to know if these peptides follow all the same mode of action. In addition, the mode of action should be different from conventional antibiotics, in consequence peptide candidates can be developed further into drugs against multi-drug resistant bacteria. Here we used one short antimicrobial peptide with unknown mode of action and compared the ultrastructural changes of Escherichia coli cells after treatment with the peptide to cells treated with classic antibiotics. The key finding is that SAXS as a structure sensitive tool provides a rapid feedback on drug induced ultrastructural alterations in whole E. coli cells. We could demonstrate that ultrastructural changes depend on the used antibiotics and their specific mode of action. This is demonstrated using several well characterized antimicrobial compounds and the analysis of resulting SAXS curves by principal component analysis. To understand the result of the PCA analysis, the data is correlated with TEM images. In contrast to real space imaging techniques, SAXS allows to obtain nanoscale information averaged over approximately one million cells. The measurement takes only seconds, while conventional tests to identify a mode of action require days or weeks per single substance. The antimicrobial peptide showed a different mode of action as all tested antibiotics including polymyxin B and is therefore a good candidate for further drug development. We envision SAXS to become a useful tool within the high-throughput screening pipeline of modern drug discovery. This article is part of a Special Issue entitled: Antimicrobial peptides edited by Karl Lohner and Kai Hilpert.
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Affiliation(s)
- A R von Gundlach
- Analytical Chemistry - Biointerfaces, Ruhr-University Bochum, NC4, Universitätsstr, 150, 44780 Bochum, Germany
| | - V M Garamus
- Helmholtz-Zentrum Geesthacht, Zentrum für Material- und Küstenforschung GmbH, Max-Planck-Straße 1, 21502 Geesthacht, Germany
| | - T Gorniak
- Analytical Chemistry - Biointerfaces, Ruhr-University Bochum, NC4, Universitätsstr, 150, 44780 Bochum, Germany
| | - H A Davies
- Life Health and Chemical Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA, United Kingdom
| | - M Reischl
- Institute for Applied Computer Science (IAI), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - R Mikut
- Institute for Applied Computer Science (IAI), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - K Hilpert
- Institute of Infection and Immunology, St. George's University of London (SGUL), Cranmer Terrace, London SW17 0RE, United Kingdom
| | - A Rosenhahn
- Analytical Chemistry - Biointerfaces, Ruhr-University Bochum, NC4, Universitätsstr, 150, 44780 Bochum, Germany
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Chuvashova IG, Vanetsev AS, Gaitko OM, Kopitsa GP, Garamus VM, Orlovskii YV, Tret’yakov YD. Effect of synthesis conditions of the micro- and mesostructure of monodisperse Y(OH)CO3 powders. Dokl Chem 2012. [DOI: 10.1134/s0012500812100011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Avdeev MV, Blagoveshchenskii NM, Garamus VM, Novikov AG, Puchkov AV. Investigation of the tripoli porous structure by small-angle neutron scattering. CRYSTALLOGR REP+ 2011. [DOI: 10.1134/s1063774511070042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Filippov SK, Porsch B, Sergeeva OY, Olifirenko AS, Lesnichin SB, Domnina NS, Komarova EA, Lezov AV, Garamus VM, Walterova Z, Stepanek P. Molecular properties of hybrid macromolecular antioxidants: dextran hydrophobically modified by sterically hindered phenols. Eur Phys J E Soft Matter 2011; 34:123. [PMID: 22105139 DOI: 10.1140/epje/i2011-11123-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 10/25/2011] [Indexed: 05/31/2023]
Abstract
The conformation properties of clinically relevant hybrid macromolecular antioxidants (dextran hydrophobically modified by sterically hindered phenols) in aqueous solution were characterized by a combination of dynamic light scattering (DLS), size exclusion chromatography (SEC), and small-angle neutron scattering (SANS). We were able to split and analyze separately two different types of polydispersity -polydispersity over molecular weights and the one over substitution degree. The properties of the hybrid macromolecules are determined by the number of hydrophobic antioxidants in a single molecule. An insertion of hydrophobic groups into a hydrophilic chain changes the conformation of a single conjugate macromolecule. We have established that with the increasing of a number of hydrophobic antioxidant groups, a conformational transition occurs where a single conjugate undergoes a transition from a Gaussian coil conformation to a more compact structure.
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Affiliation(s)
- S K Filippov
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
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Aksenov VL, Avdeev MV, Shulenina AV, Zubavichus YV, Veligzhanin AA, Rosta L, Garamus VM, Vekas L. Neutron and synchrotron radiation scattering by nonpolar magnetic fluids. CRYSTALLOGR REP+ 2011. [DOI: 10.1134/s1063774511050026] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Petrenko VI, Avdeev MV, Garamus VM, Aksenov VL, Rosta L, Bulavin LA. Formation of LC-phase in concentrated solutions of monocarboxylic acids by SANS. Acta Crystallogr A 2011. [DOI: 10.1107/s0108767311089999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Knaapila M, Evans RC, Gutacker A, Garamus VM, Torkkeli M, Adamczyk S, Forster M, Scherf U, Burrows HD. Solvent dependent assembly of a polyfluorene-polythiophene "rod-rod" block copolyelectrolyte: influence on photophysical properties. Langmuir 2010; 26:5056-5066. [PMID: 20085283 DOI: 10.1021/la903520w] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We report the solvent-driven assembly of a polyelectrolytic polyfluorene-polythiophene diblock copolymer-poly[9,9-bis(2-ethylhexyl)fluorene]-b-poly[3-(6-trimethylammoniumhexyl)thiophene] (PF2/6-b-P3TMAHT)-in tetrahydrofuran (THF), water, their 1:1 mixture and in subsequently prepared thin films, as investigated using a combination of scattering, microscopic and photoluminescence techniques. In solution PF2/6-b-P3TMAHT forms large (>100 nm) aggregates which undergo a transition from objects with surface fractal interface (THF) to ones with a significant planar component due to the presence of the 2-dimensionally merged ribbon-like aggregates or fused walls of the observed vesicular aggregates [THF-water (1:1)]. In THF-water and water the blocks are loosely segregated into P3TMAHT and PF2/6 rich domains, with PF2/6 dominating the aggregate interior. Depending on solvent, the spun films contain either aggregates with a crystalline interior (THF) or large 200 nm-2 microm vesicular aggregates embedded in a featureless matrix (THF-water and water). Structural variations are concomitant with distinctive solvatochromic changes in the photophysical properties including a color change from deep red (THF) to pale orange (THF-water and water) in solution, a decrease in fluorescence quantum yield with increasing water content, and a shift from photoluminescence of individual PF2/6 blocks (THF) to efficient PF2/6 --> P3TMAHT energy transfer (THF-water and water).
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Affiliation(s)
- M Knaapila
- Department of Physics, Institute for Energy Technology, NO-2027 Kjeller, Norway.
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Avdeev MV, Bica D, Vékás L, Aksenov VL, Feoktystov AV, Marinica O, Rosta L, Garamus VM, Willumeit R. Comparative structure analysis of non-polar organic ferrofluids stabilized by saturated mono-carboxylic acids. J Colloid Interface Sci 2009; 334:37-41. [PMID: 19376524 DOI: 10.1016/j.jcis.2009.03.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Revised: 03/17/2009] [Accepted: 03/18/2009] [Indexed: 11/16/2022]
Abstract
The structure of ferrofluids (magnetite in decahydronaphtalene) stabilized with saturated mono-carboxylic acids of different chain lengths (lauric, myristic, palmitic and stearic acids) is studied by means of magnetization analysis and small-angle neutron scattering. It is shown that in case of saturated acid surfactants, magnetite nanoparticles are dispersed in the carrier approximately with the same size distribution whose mean value and width are significantly less as compared to the classical stabilization with non-saturated oleic acid. The found thickness of the surfactant shell around magnetite is analyzed with respect to stabilizing properties of mono-carboxylic acids.
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Affiliation(s)
- M V Avdeev
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, 141980 Dubna, Moscow Reg., Russia.
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Knaapila M, Stepanyan R, Torkkeli M, Garamus VM, Galbrecht F, Nehls BS, Preis E, Scherf U, Monkman AP. Control over phase behavior and solution structure of hairy-rod polyfluorene by means of side-chain length and branching. Phys Rev E Stat Nonlin Soft Matter Phys 2008; 77:051803. [PMID: 18643093 DOI: 10.1103/physreve.77.051803] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Indexed: 05/26/2023]
Abstract
We present guidelines on how the solution structure of pi -conjugated hairy-rod polyfluorenes is controlled by the side-chain length and branching. First, the semiquantitative mean-field theory is formulated to predict the phase behavior of the system as a function of side-chain beads (N). The phase transition at N=N{ *} separates a lyotropic phase with solvent coexistence (N<N{ *}) and a metastable membrane phase (N>N{ *}). The membrane phase transforms into the isotropic phase of dissolved rodlike polymers at the temperature T_{mem}{ *}(N), which decreases both with N and with the degree of side-chain branching. This picture is complemented by polymer demixing with the transition temperature T_{IN}{ *}(N), which decreases with N . For N<N{ *}, the lyotropic phase turns isotropic with increasing T at T_{IN}{ *} . For N>N{ *}, stable membranes are predicted for T_{IN}{ *}<T<T_{mem}{ *} and metastable membranes with nematic coexistence for T<T_{IN}{ *}. Second, in experiment, samples of poly(9,9-dialkylfluorene) with N=6-10 were mixed in methylcyclohexane. For N=8 the side-chain branching was controlled by (9,9-dioctylfluorene)/(9,9-bis(2-ethylhexyl)fluorene) (F8/F2/6) random copolymers. The proportion of F8 to F2/6 repeat units was 100:0, 95:5, 90:10, 50:50, and 0:100. In accordance with the theory, lyotropic, membrane, and isotropic phases with the corresponding phase transitions were observed. For N<N{ *} approximately 6 only the lyotropic phase is present for attainable temperatures. The membrane and isotropic phases are present for N>N{ *}. T_{mem}{ *}(N) decreases from 340 K to 280 K for N > or = 8 . For copolymers, the membrane phase is found when the fraction of F8 units is at least 90%, T_{mem}{ *} decreasing with this fraction. The membrane phase contains three material types: loose sheets of two polymer layers, a better packed beta phase, and dissolved polymer. For N > or = 7 and T<T_{mem}{ *} the tendency for membrane formation becomes stronger with increasing temperature.
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Affiliation(s)
- M Knaapila
- Department of Physics, Institute for Energy Technology, P.O. Box 40, NO-2027 Kjeller, Norway.
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Knaapila M, Dias FB, Garamus VM, Almásy L, Torkkeli M, Leppänen K, Galbrecht F, Preis E, Burrows HD, Scherf U, Monkman AP. Influence of Side Chain Length on the Self-Assembly of Hairy-Rod Poly(9,9-dialkylfluorene)s in the Poor Solvent Methylcyclohexane. Macromolecules 2007. [DOI: 10.1021/ma0715728] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. Knaapila
- MAX-lab, Lund University, POB 118, SE-22100 Lund, Sweden, Department of Physics, University of Durham, South Road, DH1 3LE Durham, United Kingdom, GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany, Department of Engineering Physics and Mathematics, Helsinki University of Technology, POB 2200, FI-02015 TKK, Finland, Department of Physical Sciences, POB 64, FI-00014, University of Helsinki, Finland, Fachbereich Chemie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097
| | - F. B. Dias
- MAX-lab, Lund University, POB 118, SE-22100 Lund, Sweden, Department of Physics, University of Durham, South Road, DH1 3LE Durham, United Kingdom, GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany, Department of Engineering Physics and Mathematics, Helsinki University of Technology, POB 2200, FI-02015 TKK, Finland, Department of Physical Sciences, POB 64, FI-00014, University of Helsinki, Finland, Fachbereich Chemie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097
| | - V. M. Garamus
- MAX-lab, Lund University, POB 118, SE-22100 Lund, Sweden, Department of Physics, University of Durham, South Road, DH1 3LE Durham, United Kingdom, GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany, Department of Engineering Physics and Mathematics, Helsinki University of Technology, POB 2200, FI-02015 TKK, Finland, Department of Physical Sciences, POB 64, FI-00014, University of Helsinki, Finland, Fachbereich Chemie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097
| | - L. Almásy
- MAX-lab, Lund University, POB 118, SE-22100 Lund, Sweden, Department of Physics, University of Durham, South Road, DH1 3LE Durham, United Kingdom, GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany, Department of Engineering Physics and Mathematics, Helsinki University of Technology, POB 2200, FI-02015 TKK, Finland, Department of Physical Sciences, POB 64, FI-00014, University of Helsinki, Finland, Fachbereich Chemie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097
| | - M. Torkkeli
- MAX-lab, Lund University, POB 118, SE-22100 Lund, Sweden, Department of Physics, University of Durham, South Road, DH1 3LE Durham, United Kingdom, GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany, Department of Engineering Physics and Mathematics, Helsinki University of Technology, POB 2200, FI-02015 TKK, Finland, Department of Physical Sciences, POB 64, FI-00014, University of Helsinki, Finland, Fachbereich Chemie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097
| | - K. Leppänen
- MAX-lab, Lund University, POB 118, SE-22100 Lund, Sweden, Department of Physics, University of Durham, South Road, DH1 3LE Durham, United Kingdom, GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany, Department of Engineering Physics and Mathematics, Helsinki University of Technology, POB 2200, FI-02015 TKK, Finland, Department of Physical Sciences, POB 64, FI-00014, University of Helsinki, Finland, Fachbereich Chemie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097
| | - F. Galbrecht
- MAX-lab, Lund University, POB 118, SE-22100 Lund, Sweden, Department of Physics, University of Durham, South Road, DH1 3LE Durham, United Kingdom, GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany, Department of Engineering Physics and Mathematics, Helsinki University of Technology, POB 2200, FI-02015 TKK, Finland, Department of Physical Sciences, POB 64, FI-00014, University of Helsinki, Finland, Fachbereich Chemie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097
| | - E. Preis
- MAX-lab, Lund University, POB 118, SE-22100 Lund, Sweden, Department of Physics, University of Durham, South Road, DH1 3LE Durham, United Kingdom, GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany, Department of Engineering Physics and Mathematics, Helsinki University of Technology, POB 2200, FI-02015 TKK, Finland, Department of Physical Sciences, POB 64, FI-00014, University of Helsinki, Finland, Fachbereich Chemie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097
| | - H. D. Burrows
- MAX-lab, Lund University, POB 118, SE-22100 Lund, Sweden, Department of Physics, University of Durham, South Road, DH1 3LE Durham, United Kingdom, GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany, Department of Engineering Physics and Mathematics, Helsinki University of Technology, POB 2200, FI-02015 TKK, Finland, Department of Physical Sciences, POB 64, FI-00014, University of Helsinki, Finland, Fachbereich Chemie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097
| | - U. Scherf
- MAX-lab, Lund University, POB 118, SE-22100 Lund, Sweden, Department of Physics, University of Durham, South Road, DH1 3LE Durham, United Kingdom, GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany, Department of Engineering Physics and Mathematics, Helsinki University of Technology, POB 2200, FI-02015 TKK, Finland, Department of Physical Sciences, POB 64, FI-00014, University of Helsinki, Finland, Fachbereich Chemie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097
| | - A. P. Monkman
- MAX-lab, Lund University, POB 118, SE-22100 Lund, Sweden, Department of Physics, University of Durham, South Road, DH1 3LE Durham, United Kingdom, GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany, Department of Engineering Physics and Mathematics, Helsinki University of Technology, POB 2200, FI-02015 TKK, Finland, Department of Physical Sciences, POB 64, FI-00014, University of Helsinki, Finland, Fachbereich Chemie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097
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Halacheva S, Rangelov S, Garamus VM. Structure and Interactions in Large Compound Particles Formed by Polyglycidol-Based Analogues to Pluronic Copolymers in Aqueous Solution. Macromolecules 2007. [DOI: 10.1021/ma071151q] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- S. Halacheva
- Institute of Polymers, Bulgarian Academy of Sciences, Acad. G. Bonchev 103-A, 1113 Sofia, Bulgaria, and GKSS Research Centre, Max-Planck Strasse 1, D-21502 Geesthacht, Germany
| | - S. Rangelov
- Institute of Polymers, Bulgarian Academy of Sciences, Acad. G. Bonchev 103-A, 1113 Sofia, Bulgaria, and GKSS Research Centre, Max-Planck Strasse 1, D-21502 Geesthacht, Germany
| | - V. M. Garamus
- Institute of Polymers, Bulgarian Academy of Sciences, Acad. G. Bonchev 103-A, 1113 Sofia, Bulgaria, and GKSS Research Centre, Max-Planck Strasse 1, D-21502 Geesthacht, Germany
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Krainova EA, Avdeev MV, Merkushina KV, Rodionov AI, Garamus VM, Willumait R. Structural studies of a carbonizate obtained from solid cellulose-containing waste by sulfuric acid carbonization. RUSS J APPL CHEM+ 2007. [DOI: 10.1134/s1070427207100126] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Timchenko AA, Shiryaev VM, Fedorova YY, Kihara H, Kimura K, Willumeit R, Garamus VM, Selivanova OM. Conformation of Thermus thermophilus ribosomal protein S1 in solution at different ionic strengths. Biophysics (Nagoya-shi) 2007. [DOI: 10.1134/s0006350907020030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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20
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Timchenko AA, Shiriaev VM, Fedorova II, Kihara K, Kimura K, Willumeit R, Garamus VM, Selivanova OM. [Conformation of the ribosomal protein S1 of Thermus thermophilus in solution under different ionic conditions]. Biofizika 2007; 52:216-22. [PMID: 17477047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The structure of protein SI of Thermus thermophilus (M = 61 kDa) in solution at low and moderate ionic strengths (0 M and 100 mM NaCl, respectively) has been studied by small-angle X-ray and neutron scattering. It was found that protein S1 has a globular conformation under both ionic conditions. The modelling of different packing of six homologous domains of S1 on the basis of the NMR-resolved structure of one domain showed that the best fit of calculated scattering patterns from such complexes to experimental ones is observed at a compact package of the domains. The calculated value of the radius of gyration of the models is 28-29 angtroms, which is characteristic for globular proteins with a molecular mass of about 60 kDa. It was found that protein S1 has a tendency to form associates, and the type of the associate depends on ionic strength. These associates have, in general, two or three monomers at a moderate ionic strength, while at a low ionic strength the number of monomers exceeds three and they are packed in a compact manner. Strongly elongated associates were observed in neutron experiments at a moderate ionic strength in heavy water. The association of protein molecules was also confirmed by the data of dynamic light scattering. From these data, the translational diffusion coefficient of protein S1 at a moderate ionic strength was calculated to be (D20,w = (2.7 +/- 0.1) x 10(-7)cm2/s). This value is essentially smaller than the expected value (D20,w = (5.8 - 6.0) x 10(-7)cm2/s) for the S1 monomer in the globular conformation, indicating the association of protein molecules under equilibrium conditions.
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21
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Knaapila M, Garamus VM, Dias FB, Almásy L, Galbrecht F, Charas A, Morgado J, Burrows HD, Scherf U, Monkman AP. Influence of Solvent Quality on the Self-Organization of Archetypical Hairy Rods−Branched and Linear Side Chain Polyfluorenes: Rodlike Chains versus “Beta-Sheets” in Solution. Macromolecules 2006. [DOI: 10.1021/ma060886c] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. Knaapila
- Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK; GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany; Research Institute for Solid State Physics and Optics, P.O. Box 49, Budapest-1525, Hungary; Macromolekulare Chemie, Institut für Polymertechnologie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097 Wuppertal, Germany; Instituto de Telecomunicações, Instituto Superior Técnico, Av. Rovisco Pais, P-1049-001 Lisboa, Portugal; and Departamento de
| | - V. M. Garamus
- Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK; GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany; Research Institute for Solid State Physics and Optics, P.O. Box 49, Budapest-1525, Hungary; Macromolekulare Chemie, Institut für Polymertechnologie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097 Wuppertal, Germany; Instituto de Telecomunicações, Instituto Superior Técnico, Av. Rovisco Pais, P-1049-001 Lisboa, Portugal; and Departamento de
| | - F. B. Dias
- Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK; GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany; Research Institute for Solid State Physics and Optics, P.O. Box 49, Budapest-1525, Hungary; Macromolekulare Chemie, Institut für Polymertechnologie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097 Wuppertal, Germany; Instituto de Telecomunicações, Instituto Superior Técnico, Av. Rovisco Pais, P-1049-001 Lisboa, Portugal; and Departamento de
| | - L. Almásy
- Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK; GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany; Research Institute for Solid State Physics and Optics, P.O. Box 49, Budapest-1525, Hungary; Macromolekulare Chemie, Institut für Polymertechnologie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097 Wuppertal, Germany; Instituto de Telecomunicações, Instituto Superior Técnico, Av. Rovisco Pais, P-1049-001 Lisboa, Portugal; and Departamento de
| | - F. Galbrecht
- Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK; GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany; Research Institute for Solid State Physics and Optics, P.O. Box 49, Budapest-1525, Hungary; Macromolekulare Chemie, Institut für Polymertechnologie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097 Wuppertal, Germany; Instituto de Telecomunicações, Instituto Superior Técnico, Av. Rovisco Pais, P-1049-001 Lisboa, Portugal; and Departamento de
| | - A. Charas
- Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK; GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany; Research Institute for Solid State Physics and Optics, P.O. Box 49, Budapest-1525, Hungary; Macromolekulare Chemie, Institut für Polymertechnologie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097 Wuppertal, Germany; Instituto de Telecomunicações, Instituto Superior Técnico, Av. Rovisco Pais, P-1049-001 Lisboa, Portugal; and Departamento de
| | - J. Morgado
- Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK; GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany; Research Institute for Solid State Physics and Optics, P.O. Box 49, Budapest-1525, Hungary; Macromolekulare Chemie, Institut für Polymertechnologie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097 Wuppertal, Germany; Instituto de Telecomunicações, Instituto Superior Técnico, Av. Rovisco Pais, P-1049-001 Lisboa, Portugal; and Departamento de
| | - H. D. Burrows
- Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK; GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany; Research Institute for Solid State Physics and Optics, P.O. Box 49, Budapest-1525, Hungary; Macromolekulare Chemie, Institut für Polymertechnologie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097 Wuppertal, Germany; Instituto de Telecomunicações, Instituto Superior Técnico, Av. Rovisco Pais, P-1049-001 Lisboa, Portugal; and Departamento de
| | - U. Scherf
- Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK; GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany; Research Institute for Solid State Physics and Optics, P.O. Box 49, Budapest-1525, Hungary; Macromolekulare Chemie, Institut für Polymertechnologie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097 Wuppertal, Germany; Instituto de Telecomunicações, Instituto Superior Técnico, Av. Rovisco Pais, P-1049-001 Lisboa, Portugal; and Departamento de
| | - A. P. Monkman
- Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK; GKSS Research Centre, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany; Research Institute for Solid State Physics and Optics, P.O. Box 49, Budapest-1525, Hungary; Macromolekulare Chemie, Institut für Polymertechnologie, Bergische Universität Wuppertal, Gauss-Strasse 20, D-42097 Wuppertal, Germany; Instituto de Telecomunicações, Instituto Superior Técnico, Av. Rovisco Pais, P-1049-001 Lisboa, Portugal; and Departamento de
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Thiesen PH, Rosenfeld H, Konidala P, Garamus VM, He L, Prange A, Niemeyer B. Glycolipids from a colloid chemical point of view. J Biotechnol 2006; 124:284-301. [PMID: 16707183 DOI: 10.1016/j.jbiotec.2006.03.032] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2005] [Revised: 02/24/2006] [Accepted: 03/29/2006] [Indexed: 11/23/2022]
Abstract
Glycolipids are a group of compounds with a broad range of applications. Two types of glycolipids (alkylpolyglycosides and gangliosides) were examined with regard to their physicochemical properties. Despite their structural differences, they have in common that they are amphiphilic molecules and able to aggregate to form monolayers, bilayers, micelles, lyothropic mesophases or vesicles. The structures of glycolipid micelles were investigated by different experimental techniques in addition to molecular dynamic simulations. The knowledge of the physicochemical properties of gangliosides enables a better understanding of their biological functions. Structural features were obtained for the monosialogangliosides GM1, GM2 and GT1b from bovine brain by means of mass spectrometry. Further the aggregation behaviour was determined by small-angle neutron and dynamic light scattering experiments. Interaction studies of these compounds were carried out by means of surface plasmon resonance using gangliosides incorporated liposomes. They were used as model membranes that interact with the lectins WGA, RCA and HPA. The interaction of lectins immobilized to a modified silicon surface was investigated by in-situ ellipsometry.
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Affiliation(s)
- P H Thiesen
- Helmut-Schmidt-University/University of the Federal Armed Forces Hamburg, Germany
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Avdeev MV, Aksenov VL, Balasoiu M, Garamus VM, Schreyer A, Török G, Rosta L, Bica D, Vékás L. Comparative analysis of the structure of sterically stabilized ferrofluids on polar carriers by small-angle neutron scattering. J Colloid Interface Sci 2006; 295:100-7. [PMID: 16102775 DOI: 10.1016/j.jcis.2005.07.048] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2004] [Revised: 05/13/2005] [Accepted: 07/23/2005] [Indexed: 11/20/2022]
Abstract
Results of experiments on small-angle neutron scattering from ferrofluids on polar carriers (pentanol, water, methyl-ethyl-ketone), with double-layer sterical stabilization of magnetic nanoparticles, are reported. Several types of spatial structural organization are observed. The structure of highly stable pentanol-based samples is similar to that of stable ferrofluids based on organic non-polar carriers (e.g., benzene) with mono-layer covered magnetic nanoparticles. At the same time, the effect of the interparticle interaction on the scattering is stronger in polar ferrofluids because of the structural difference in the surfactant shell. The structure of the studied methyl-ethyl-ketone- and water-based ferrofluids essentially different from the previous case. The formation of large (>100 nm in size) elongated or fractal aggregates, respectively, is detected even in the absence of external magnetic field, which corresponds to weaker stability of these types of ferrofluids. The structure of the fractal aggregates in water-based ferrofluids does not depend on the particle concentration, but it is sensitive to temperature. A temperature increase results in a decrease in their fractal dimension reflecting destruction of the aggregates. In addition, in water-based ferrofluids these aggregates consist of small (radius approximately 10 nm) and temperature-stable primary aggregates.
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Affiliation(s)
- M V Avdeev
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia.
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Zbytovská J, Kiselev MA, Funari SS, Garamus VM, Wartewig S, Neubert R. Influence of phytosphingosine-type ceramides on the structure of DMPC membrane. Chem Phys Lipids 2005; 138:69-80. [PMID: 16202987 DOI: 10.1016/j.chemphyslip.2005.08.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2005] [Revised: 08/09/2005] [Accepted: 08/17/2005] [Indexed: 11/26/2022]
Abstract
The present paper describes the influence of the ceramides with phytosphingosine base, N-stearoylphytosphingosine (Cer[NP]) and alpha-hydroxy-N-stearoylphytosphingosine (Cer[AP]), on the structure and properties of multilamellar (MLVs) and unilamellar vesicles (ULVs) of dimyristoylphosphatidylcholine (DMPC). The lamellar repeat distance, D, has been measured at various temperatures using small angle X-ray diffraction. The incorporation of ceramides into the DMPC membrane causes larger D compared to pure DMPC membrane. For both ceramide types, at 32 degrees C, there is a linear relationship between the D value and the ceramide concentration. However, there is no such dependence at 13 or 60 degrees C. Unlike Cer[AP], Cer[NP] induces a new phase with a repeat distance of 38.5A. The membrane thickness and the vesicle radius of ULVs in water and in sucrose solution were calculated from small angle neutron scattering curves. Phytosphingosine ceramides increase both the membrane thickness and the radius in comparison to pure DMPC ULVs. The stability of ULVs in time was studied by dynamic light scattering. Both ceramides induce an aggregation of the ULVs into micrometer sized non-multilamellar structures in pure water. Presence of sucrose in the environment averts the vesicle aggregation.
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Affiliation(s)
- J Zbytovská
- Department of Pharmacy, Martin-Luther-University Halle-Wittenberg, Wolfgang-Langenbeck Str. 4, D-06120 Halle/Saale, Germany.
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Prado LASDA, Goerigk G, Ponce ML, Garamus VM, Wittich H, Willumeit R, Schulte K, Nunes SP. Characterization of proton-conducting organic-inorganic polymeric materials by ASAXS. ACTA ACUST UNITED AC 2005. [DOI: 10.1002/polb.20576] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Bastardo LA, Garamus VM, Bergström M, Claesson PM. The Structures of Complexes between Polyethylene Imine and Sodium Dodecyl Sulfate in D2O: A Scattering Study. J Phys Chem B 2004; 109:167-74. [PMID: 16851000 DOI: 10.1021/jp046837o] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The association between a highly branched polyelectrolyte with ionizable groups, polyethylene imine (PEI), and an anionic surfactant, sodium dodecyl sulfate (SDS), has been investigated at two pH values, using small-angle neutron and light scattering. The scattering data allow us to obtain a detailed picture of the association structures formed. Small-angle neutron scattering (SANS) measurements in solutions containing highly charged PEI at low pH and low SDS concentrations indicate the presence of disklike aggregates. The aggregates change to a more complex three-dimensional structure with increasing surfactant concentration. One pronounced feature in the scattering curves is the presence of a Bragg-like peak at high q-values observed at a surfactant concentration of 4.2 mM and above. This scattering feature is attributed to the formation of a common well-ordered PEI/SDS structure, in analogue to what has been reported for other polyelectrolyte-surfactant systems. Precipitation occurred at the charge neutralization point, and X-ray diffraction measurements on the precipitate confirmed the existence of an ordered structure within the PEI/SDS aggregates, which was identified as a lamellar internal organization. Polyethylene imine has a low charge density in alkaline solutions. At pH 10.1 and under conditions where the surfactant was contrast matched, the SANS scattering curves showed only small changes with increasing surfactant concentration. This suggests that the polymer acts as a template onto which the surfactant molecules aggregate. Data from both static light scattering and SANS recorded under conditions where SDS and to a lower degree PEI contribute to the scattering were found to be consistent with a structure of stacked elliptic bilayers. These structures increased in size and became more compact as the surfactant concentration was increased up to the charge neutralization point.
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Affiliation(s)
- L A Bastardo
- Department of Chemistry, Surface Chemistry, Drottning Kristinas väg 51, Royal Institute of Technology, SE-10044 Stockholm, Sweden.
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Milkereit G, Garamus VM, Veermans K, Willumeit R, Vill V. Synthesis and mesogenic properties of a Y-shaped glyco-glycero-lipid. Chem Phys Lipids 2004; 131:51-61. [PMID: 15210364 DOI: 10.1016/j.chemphyslip.2004.03.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2003] [Revised: 03/24/2004] [Accepted: 03/31/2004] [Indexed: 11/20/2022]
Abstract
We synthesised a new glyco-glycero-lipid [1,3-di-O-(beta-D-glucopyranosyl)-2-deoxy-2-amino-N-palmitoyl-sn-glycerol] with a Y-shaped structure bearing two sugar head groups and only one fatty acid chain. Instead of an ester linkage between the glycerol and the fatty acid an amido function was introduced. The mesogenic properties were investigated using polarising microscopy and are discussed with respect to similar compounds. The lyotropism was measured using the contact preparation method and small-angle neutron-scattering.
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Affiliation(s)
- G Milkereit
- Institute of Organic Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
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Avdeev MV, Khokhryakov AA, Tropin TV, Andrievsky GV, Klochkov VK, Derevyanchenko LI, Rosta L, Garamus VM, Priezzhev VB, Korobov MV, Aksenov VL. Structural features of molecular-colloidal solutions of C60 fullerenes in water by small-angle neutron scattering. Langmuir 2004; 20:4363-8. [PMID: 15969139 DOI: 10.1021/la0361969] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Highly stable and reproducible molecular-colloidal water solutions of C60 fullerenes (FWS) obtained by transferring fullerenes from an organic solution into an aqueous phase with the help of ultrasonic treatment are investigated by means of small-angle neutron scattering (SANS). A polydispersity in the size of detected particles up to 84 nm is revealed. These particles are slightly anisotropic and have a characteristic size of approximately 70 nm. Along with it, there are some indications that a significant part of fullerenes composes particles with the size of the order of 1 nm. The contrast variation based on mixtures of light and heavy water shows that the mean scattering length density of the particles is close to that of the packed fullerene associates as well as that the characteristic size of possible fluctuations of the scattering length density within the particles does not exceed 2 nm. A smooth surface resulting in the Porod law for the scattering is detected. A number of models discussed in the literature are considered with respect to the SANS data.
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Affiliation(s)
- M V Avdeev
- Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia
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Nadutov VM, Garamus VM. Small-Angle Neutron Scattering and Mossbauer Effect in Austenitic N- and C-containing steels. Acta Crystallogr A 2000. [DOI: 10.1107/s0108767300025095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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