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Forschung - Research

Group Prof. E. Donath

Research interests

The research focuses on the understanding of organization and functioning of soft matter nanoscale materials with a special focus on biopolymers.

Polyelectrolyte multilayers are step-wise assembled on colloids or cells employing the electrostatic as well as other types of interaction between the multilayer constituents. As layer constituents various materials can substitute one ore more polyelectrolyte layers. Nanocomposite multilayers with tailored biological, physical and chemical properties can be engineered.

The colloidal core or biological cell can be removed resulting in hollow shells with ultrathin layers. These novel colloidal structures are investigated with respect to their physical, chemical and biological properties. A wide variety of methods is employed to study the thermodynamical, mechanical, electrical and permeability properties of the multilayer composites.

Properties, organization and application of ultrathin polyelectrolyte multilayers on colloids, cells and capsules. Design of Artificial Cells.

Scheme of a polyelectrolyte-lipid-protein composite particle
Scheme of a polyelectrolyte-lipid-protein composite particle

The encapsulation of various materials with multifunctional layers is an issue with great practical significance in areas, such as drug delivery, sensing and advanced materials.

Of special interest is the fabrication of bio-nanocomposites aiming on artificial nanoscale structures with in-built biological functions. For example, lipid layers can be combined with polyelctrolyte multilayer cushions as replicals of cells.

The hollow shells can be used as nanoreaction cages and templates for precipitation and crystallization. This area of research is closely related to the understanding of biomimetic principles.

Achievements

Ultrathin polyelectrolyte multilayers were stepwise deposited onto a variety of colloidal particles, including biological cells and a number of soluble colloids. The driving force of the multilayer assembling is the electrostatic attraction and entropy increase at each step of macroion adsorption.

Microelectrophoresis, single particle light scattering and fluorescence spectroscopy have been applied for controlling the regularity of the multilayer assembly process. Light Scattering and fluorescence intensity increased linearily with the number of adsorbed layers. Layer thickness increments of as small as 1 nm can be assessed with single particle light scattering performed on a custom-made device. Fluorescence energy transfer measurements between labelled layer constituents provided an insight into the nanoscale topology of multilayers. Small angle neutron scattering has been applied to directly measure the layer thickness on colloidal particles.

Weakly cross-linked melamine formaldehyde (MF) particles, various organic dye crystals, silica and biological cells are used as templates for the production of hollow polyelectrolyte shells. These novel structures are obtained after removal of the templating core. Hollow polyelectrolyte capsules with diameters ranging from 0.1 to 10 microns and wall thicknesses from few to tens of nanometers, respectively, were obtained. Scanning and transmission electron microscopy, as well as confocal microscopy were employed to characterize the morphology of coated colloids and capsules. Electrorotation was employed to measure the conductance and capacitance of capsules. Scanning force microscopy (SFM) was used to investigate the texture and thickness of the capsule walls. Single capsules were mounted on a SFM cantilever, which was subsequently used for characterizing interaction forces. It was shown that the layer structure can be influenced by annealing at elevated temperatures. Osmotic pressure differences were created between the capsule interior and the bulk. The resulting capsule wall deformatiuon was used to measure the mechanical properties of the ultrathin film. Confocal laser scanning microscopy (CLSM) is a key technique to visualize the capsule morphology as well as the distribution compounds between the interior and the bulk. With CLSM as well as with spectroscopy techniques the permeability properties of the layers were studied. It was shown that the permeability can be tuned by the pH value, by the electrolyte concentration and annealing. This is an important means for controlling encapsulation.

To date a large variety of materials ranging from inorganics and nanoparticles to synthetic and biopolymers have been introduced into the hollow capsules by means of permeability control, controlled precipitation, capsule wall decomposition, and synthesis. Synthesis of polymers was performed by making use of the exclusion properties of the shell wall. Monomers can pass the wall while the synthesized polymer remains confined. Layers with interesting optical properties were obtained when dyes were used as layer materials. By controlling the topology of nucleation it became possible to selectively fill the capsules with solid low molecular weight materials. The intercalation of lipid bilayers into the polyelectrolyte multilayer system was a major step forward to an "artificial cell". These novel colloidal structures may have wide-ranging applications as containers for a large class of materials, as templates for nanocomposites, or as cages for chemical reactions. The polymer capsule wall composition can be tailored to meet various multipurpose requirements.

Tired of so many text lines?
Try this! Capsules for Drug Delivery
A presentation by Prof. Dr. Edwin Donath
... or this ...Von supramolekularen Strukturen zu Wirkstoffträgern und künstlichen Zellen
Another presentation by Prof. Dr. Edwin Donath - in deutsch :-)
... or this!Posters
Compilation of recent conference posters

Projects

Fabrikation und Charakterisierung von kolloidalen Biokompositen unter Verwendung von viralen Bauelementen

Ziel dieses Forschungsprojektes ist es, authentische Protein- und Peptidfunktionen auf kolloidale Träger und Arrays zu übertragen und deren Struktur, Funktion und Stabilität zu untersuchen. Im medizinischen Bereich sollen damit diagnostische und immunologische Anwendungen anvisiert werden.

Polyelectrolyte-Lipid Wechselwirkung auf kolloidalen Biokompositen

Ziel der geplanten Untersuchungen ist es, maßgeschneiderte Lipidschichten auf Polyelektrolytmultischichten aufzubringen. Dazu ist ein weit über den bisherigen Wissensstand hinausgehendes Verständnis der Lipid-Polyelektrolytwechselwirkung notwendig. Die Lipidschichten dienen als Basis für die weitere Ausrüstung mit biologischen Funktionen.

Mechanische Eigenschaften von Viren - Relevanz für Fusionsprozesse

Ziel dieser Untersuchungen ist es, mit Kraftmikroskopie die mechanischen Eigenschaften und die Stabilität von viralen Kapsiden und Viren zu messen und in Bezug zu Fusionskompetenz und der Verwendung von Viren und viralen Partikeln als Bauelemente für Komposite zu bringen. Zum Beispiel geht mit der Fusion von lipidbehüllten Viren im Endosom die Freisetzung des Genoms in das Zytoplasma einher. Dieser Prozess beinhaltet die Destabilisierung des Kapsids. Darüber ist wenig bekannt, obwohl dieser Prozess ein entscheidender Schritt bei der Infektion auf zellulärer Ebene ist.

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Future Plans

While in the past success in the field of capsule fabrication and layer engineering has often been achieved empirically, now a deeper understanding of the basis of the astonishing multilayer versatility regarding their functions and properties is clearly necessary. Research will be conducted among other questions toward

  • the understanding of the layer permeability. It is interesting to know how the permeability for various substances depends on the properties of the layer building constituents. Answering this question will help to understand the molecular details of the layer organization. It is still not clear how the various substances pass the multilayer. While some substances may diffuse through the layer, others may permeate predominantly across defects.
  • Once the mechanism of permeability is understood the problem, of how the permeability can be (reversibly) controlled, can be adressed. Until now it was possible to change the permeability by pH, salt concentration and temperature for a limited number of systems. To understand the relationship between the interaction of the layer forming constituents and the permeability needs future work..
  • The dynamics of the layer constituents is poorly understood. New approaches are necessary to address this important question..
  • The layer structure is fabricated by controlling the sequence of adsorption. Clearly, the system is characterized by low entropy. By investigating entropically driven layer structure changes we will able to learn about the strenght of intermolecular forces in the layer. The stability of the layer is an important issue concerning future application..

It is challenging to fabricate capsules with biological functions, i. e. "artificial cells". To achieve this goal booth the interior and the capsule wall will be engineered accordingly. Until know some biomodifications have been already accomplished. It was possible to intercalate one or more lipid bilayers into the multilayer wall. Enzymes have been introduced both into the wall as well as into the capsule interior. However, the intergration of the biologhically most important membrane functions, such as transfer of mass, information and energy has not been attempted yet. To reach this aim will require concentrated efforts to understand

  • the properties of the bilayer sandwiched between neighbouring polyelectrolyte layers. Little is know about the coupling, the curvature and the phase state. It will be important to vary the composition to arrive at a bilayer state most suitable for the subsequent incorporation of membrane functions.
  • It is important to understand how the function of membrane proteins will be imfluenced by the polymeric support. Biological polyelectrolytes will play a major role for the reconstruction of the "artificial cell".

Much work remains to be done to understand the precipitation and crystallization processes in the presence of capsules as templates. While it is evident that the localization of the nucleation side is decisive,

  • ways of how to control the start of the process have to be explored.
  • Very little is known about the influence of substance permeation on the efficiency of the precipitation process and the morphology of the growing inside precipitate or crystal.
  • These studies have a close relation to biomimetic principles. Biological systems employ both, template control as well as rate control for building up astonishingly variable and superior nanocomposites out of a limited number of materials. Hence, future work should be directed to employ the versatility of the shell wall and the possibility to reversibly control its function for mimicking the synthesis of biocomposite materials.

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Research Techniques

  • Electrophoresis
  • Dynamic light scattering
  • Single Particle Light Scattering
  • Small Angle Neutron Scattering
  • Small and Wide Angle X-Ray Scattering
  • UV-VIS and Fluorescence Spectroscopy (Förster Energy Transfer)
  • NMR Spectroscopy
  • Infrared Spectroscopy
  • Scanning Force Microscopy (Molecular Force Spectroscopy)
  • Transmission and Scanning Electron Microscopy, Freeze Fracturing
  • Confocal Laser Scanning Microscopy
  • Fluorescence Correlation Spectroscopy
  • Micromechanics

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Collaborations

Within the institute:

  • Dr. D. Huster: NMR-Untersuchungen zur Kapselstruktur und Permeabilität
  • Dr. U. Reibetanz / Dr. J. Leßig: Lipidschichten auf Polyelektrolytkapseln

with external groups:

  • G. Brzesinsky (Max-Planck-Institute of Colloids and Surfaces): Polyelectrolyte-Lipid interaction - Artificial Cells
  • H. Riegler (Max-Planck-Institute of Colloids and Surfaces): Adhesion and Interaction
  • H. Bäumler (Humboldt-Universität, Charité): Biological Cells as templates
  • F. Kremer (Universität Leipzig): Capsule and colloid Interactions
  • S. Bruzzano (Fraunhofer Institute of Applied Polymer Research): Functional Polymers
  • M. Egger (University Bern): Membrane proteins as layer constituents
  • R. Bernhardt (University Saarbrücken): Membrane proteins as layer constituents
  • G. Fuhr (Fraunhofer Institute of Biomedical Techniques): Electrorotation and Electromanipulation
  • A. Herrmann (Humboldt-University Berlin): Membrane proteins as layer constituents
  • K. Überla (Ruhr University Bochum): Viral membrane proteins as layer constituents
  • K. H. Lerche (microparticles GmbH): New template materials
  • N. Buske (Berlin Heart GmbH): Superparamagnetic particles as layer constituents
  • A. Voigt (Capsulution Nanoscience AG): Practical applications
  • H. Auweter (BASF): Encapsulation of dyes and drugs
  • S. Hofmann (Bayer AG): Encapsulation of drugs

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Curriculum vitae of Prof. Dr. Edwin Donath

  • 2001 appointed as professor to Leipzig University, Institute of Medical Physics and Biophysics
  • Since 1997 member of research staff of the Max Planck Institute of Colloids and Interfaces , Department Interfaces
  • 1996 Research staff member at Rostock University, School of Medicine, Biophysics
  • 1991 - 1995 C2 at Humboldt University Berlin, Department of Biophysics, "Physical Chemistry of Biological Interfaces"
  • 1987-1990 Dozent of Biophysics, Humboldt University Berlin, Department of Biophysics
  • 1984 Habilitation and Venia Legendi at Humboldt-University. Thesis topic: Interaction of Biological Interfaces and Fusion of Biomembranes.
  • 1979 PhD in Biophysics at Humboldt University. Thesis: Electrokinetics at Biological Interfaces
  • 1974 Diploma in physics (Lipid Membrane Ion Transport) at Moscow State University

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Group members

NameTitelRaumTelefone-mail

Head

Edwin Donath   Prof. Dr. rer. nat. habil. 251 97 15704 edwin.donath@medizin.uni-leipzig.de

Group members

Thomas Beruda   cand. med. dent. 255.3 97 15776 t.beruda@helimail.de
Luis Cuellar   Dipl.-Phys. 255.1 97 15761 luis.cuellar@medizin.uni-leipzig.de
Irina Estrela-Lopis   Dr. rer. nat. 252 97 15702 irina.estrela-lopis@medizin.uni-leipzig.de
Felix Meinhövel   cand. med. dent. 255.3 97 15776 Felix.Meinhoevel@medizin.uni-leipzig.de
Elke Typlt   Dipl.-Biochem. (BTA) 250 97 15725 elke.typlt@medizin.uni-leipzig.de

Former group members

NameTitelnowe-mail
Christian Bitterlich   Dipl.-Phys.
Martin Fischlechner   Dr. rer. nat. University of Cambridge martin.fischlechner@medizin.uni-leipzig.de
David Halozan   Dr. rer. nat. University of Maribor, Maribor, Slovenia david.halozan@uni-mb.si
Guido Köhler   Dr. rer. nat. Sächsische LehmbauGruppe koehlerg@lehmbaugruppe.de
Stefano Leporatti   Dr. rer. nat. National Nanotechnology Laboratory, University of Lecce, Italien stefano.leporatti@unile.it
Benedikt Maas   cand. med. dent. benhuman@gmx.de
Stephan Meyer   cand. med. dent.
Sergio Moya   Dr. rer. nat.  Department of Advanced Materials, Centro de Investigacion en Quimica Aplicada (CIQA), Saltillo, Mexico smoya@ciqa.mx
Christopher Rosche   cand. med. dent.
Andreas Schnäckel   cand. med. dent.

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Publications

  • I. Estrela-Lopis, J.J. Iturri Ramos, E. Donath, S.E. Moya: Spectroscopic studies on the competitive interaction between polystyrene sodium sulfonate with polycations and the N-tetradecyl trimethyl ammonium bromide surfactant. J Phys Chem B. 14 (2010) 84-91
  • JJ. Iturri Ramos, I. Llarena, L. Fernandez, S.E. Moya, E. Donath: Controlled Stripping of Polyelectrolyte Multilayers by Quaternary Ammonium Surfactants. Macromol. Rapid Commun. 30 (2009) 1756-1761
  • D. Halozan, U. Reibetanz, M. Brumen, E. Donath: Polyelectrolyte microcapsules and coated CaCO3 particles as fluorescence activated sensors in flowmetry. Colloids and Surfaces A: Physicochem. Eng. Aspects 342 (2009) 115–121. 
  • A. Bunge, M. Fischlechner, M. Loew, A. Arbuzova, A. Herrmann, D. Huster: Characterization of Lipid Bilayers Adsorbed on Spherical LbL-Support. Soft Matter 5 (2009) 3331 - 3339
  • E. Donath: Biosensors: Viruses for ultrasensitive assays. Nat Nanotechnol. 4 (2009) 215-216. 
  • J. Irigoyen, S.E. Moya, J.J. Iturri, I. Llarena, O. Azzaroni, E. Donath: Specific Zeta-Potential Response of Layer by Layer Coated Colloidal Particles Triggered by Polyelectrolyte Ion Interactions. Langmuir 25 (2009) 3374-3380
  • I. Estrela-Lopis, S. Leporatti, D. Clemens, E. Donath: Polyelectrolyte Multilayer Hollow Capsules Studied by Small Angle Neutron Scattering (SANS). Soft Matter 5 (2009) 214 - 219
  • M. Fischlechner, M. Zaulig, S. Meyer, I. Estrela-Lopis, L. Cuéllar, J.Irigoyen, P. Pescador, M. Brumen, P. Messner, S. Moya, E. Donath: Lipid layers on polyelectrolyte multilayer supports, Soft Matter 4 (2008) 2245-2258
  • S. Meyer, P. Pescador, E. Donath: Fluorescence boost in polyelectrolyte multilayer architectures. J. Phys. Cem. C 112 (2008) 1427-1434
  • D. Halozan, G.B. Sukhorukov, M. Brumen, E. Donath, H. Möhwald: Donnan equilibrium and osmotic pressure in hollow polyelectrolyte microcapsules. Acta Chim. Slov. 54 (2007) 598-604
  • M. Fischlechner, U. Reibetanz, M. Zaulig, D. Enderlein, J. Romanova, S. Leporatti, S. Moya, E. Donath: Fusion of Enveloped Virus Nanoparticles with Polyelectrolyte-Supported Lipid Membranes for the Design of Bio/Nonbio Interfaces. Nano Letters 7 (2007) 3540-3546
  • S. E. Moya, O. Azzaroni, T. Kelby, E. Donath, W. T. S. Huck: Explanation for the Apparent Absence of Collapse of Polyelectrolyte Brushes in the Presence of Bulky Ions. J. Phys. Chem. B. 111 (2007) 7034-7040
  • I. Estrela-Lopis, S. Leporatti, E. Typlt, D. Clemens, E. Donath: Small Angle Neutron Scattering Investigations (SANS) of Polyelectrolyte Multilayer Capsules Templated on Human Red Blood Cells. Langmuir 23 (2007) 7209-7215
  • U. Reibetanz, D. Halozan, M. Brumen, E. Donath: Flow cytometry of HEK 293T cells interacting with polyelectrolyte multilayer capsules containing fluorescein-labeled poly(acrylic acid) as a pH sensor. Biomacromolecules 8 (2007) 1927-1933
  • M. Fischlechner, E. Donath: Viruses as Building Blocks for Materials and Devices. Angew. Chem. Int. Ed. 46 (2007) 3184-3193
  • G. Köhler, S.E. Moya, S. Leporatti, C. Bitterlich, E. Donath: Stability and fusion of lipid layers on polyelectrolyte multilayer supports studied by colloidal force spectroscopy. Eur. Biophys. J. 36 (2007) 337-347
  • A. Schnäckel, S. Hiller, U. Reibetanz, E. Donath: Fluorescent bead arrays by means of layer-by-layer polyelectrolyte adsorption. Soft Matter 3 (2007) 200-206
  • L. Toellner, M. Fischlechner, B. Ferko, R. M. Grabherr, E. Donath: Virus-Coated LbL-Colloids as a novel multiplex suspension array for the detection and quantification of virus-specific antibodies. Clin. Chem. 52 (2006) 1575-1583
  • U. Reibetanz, C. Claus, E. Typlt, J. Hofmann, E. Donath: Defoliation and Plasmid Delivery with Layer-by-Layer Coated Colloids. Macromol. Biosci. 6 (2006) 153-160
  • S. Leporatti, A. Gerth, G. Köhler, B. Kohlstrunk, S. Hauschildt, E. Donath: Elasticity and adhesion of resting and lipopolysaccharide-stimulated macrophages. FEBS Letters 580 (2006) 450-454
  • O. Azzaroni, S.E. Moya, A.A. Brown, Z. Zheng, E. Donath, W.T.S. Huck: Polyelectrolyte Brushes as Ink Nanoreservoirs for Microcontact Printing of Ionic Species with PDMS Stamps. Adv. Func. Mat. 16 (2006) 1037-1042
  • R. Georgieva, S. E. Moya, H. Bäumler, H. Möhwald, E. Donath: Controlling ionic conductivity in lipid polyelectrolyte composite capsules by cholesterol. J. Phys. Chem. B 109 (2005) 18025-18030
  • M. Fischlechner, L. Toellner, P. Messner, R. Grabherr, E. Donath: Virus Engineered Colloidal Particles - A Novel Surface Display System. Angew. Chem. Int. Ed. 45 (2006) 784-789
  • D. Lenz, M.J. Barten, S. Hiller, A. Tárnok, U. Sack: Regenerative and predictive medicine of cardiovascular disease: The 9th Leipziger Workshop and the 2nd International Workshop on slide based cytometry. Cytometry Part A 64 (2005) 110-114
  • S. Hiller, A., Schnäckel, E. Donath: Polyelectrolyte coated particles as fluorescence markers for FACS characterization of cells. Cytometry Part A. 64A (2005) 119
  • M. Fischlechner, O. Zschörnig, J. Hofmann, E. Donath: Engineering Virus Functionalities on Colloidal Polyelectrolyte Lipid Composites. Angew Chem Int Ed Engl. 44 (2005) 2892-2895
  • S. Leporatti, R. Sczech, H. Riegler, S. Bruzzano, J. Storsberg, F. Loth, W. Jaeger, A. Laschewsky, S. Eichhorn, E. Donath: Interaction forces between cellulose microspheres and ultrathin cellulose films monitored by colloidal probe microscopy-effect of wet strength agents. J. Colloid Interface Sci. 281 (2005) 101-111
  • I. Estrela-Lopis, G. Brezesinski, H. Möhwald: Miscibility of DPPC and DPPA in monolayers at the air/water interface. Chem. Phys. Lipids 131 (2004) 71-80
  • R. Georgieva, S. Moya, E. Donath, H. Bäumler: Permeability and Conductivity of red blood cell templated polyelectrolyte capsules coated with supplementary layers. Langmuir 20 (2004) 1895 - 1900
  • S. Hiller, S. Leporatti, A. Schnäckel, E. Typlt, E. Donath: Protamine assembled in multilayers on colloidal particles can be exchanged and released. Biomacromolecules 5 (2004) 1580-1587
  • S. E. Moya, R. Georgieva, H. Bäumler, W. Richter, E. Donath: Composite Lipid Polyelectrolyte Capsules Templated on Red Blood Cells - Fabrication and Structural Characterization. Med. Biol. Eng. Comput. 41 (2003) 504-508.
  • S. Moya, W. Richter, S. Leporatti, H. Bäumler, E. Donath: Freeze-Fracture Electron Microscopy of Lipid Membranes on Colloidal Polyelectrolyte Multilayer Coated Supports. Biomacromolecules Biomacromolecules 4 (2003) 808-814.
  • C. Gao, S. Leporatti, S. Moya, E. Donath, H. Möhwald: Swelling and Shrinking of Polyelectrolyte Microcapsules in Response to Changes in Temperature and Ionic Strength. Chem. Eur. J. 9 (2003) 915-920
  • E. Donath, S. Moya, B. Neu, G. B. Sukhorukov, R. Georgieva, A. Voigt, H. Bäumler, H. Kiesewetter, H. Möhwald: Hollow polymer shells from biological templates: Fabrication and potential applications. Chem. Eur. J. 8 (2002) 5481-5485
  • Z. Dai, L. Dähne, E. Donath, H. Möhwald: Downhill energy transfer via ordered multichromophores light-harvesting capsules. J. Phys. Chem. B 106 (2002) 11501-11508
  • G. Ibarz, L. Dähne, E. Donath, H. Möhwald: Controlled permeability of polyelectrolyte capsules via defined annealing. Chem. Mat. 14 (2002) 4059-4062
  • C. Gao, E. Donath, H. Möhwald, J. Shen: Spontaneous Deposition of water-soluble substances into microcapsules: Phenomenon, mechanism, and application. Angew. Chem. 114 (2002) 3943-3947
  • H. Möhwald, H. Lichtenfeld, S. Moya, A. Voigt, G. B. Sukhorukov, S. Leporatti, L. Dähne, I. Radtchenko, A. A. Antipov, C. Gao, E. Donath: From polymeric films to nanocapsules. In "Adsorption and aggregation of surfactants in solution", Marcel Dekker, New York, (Eds. K. L. Mittal, D. O. Shah) pp. 91-104 (2002). ISBN 0-824-70843-1.
  • I. Estrela-Lopis, S. Leporatti, S. Moya, A. Brandt, E. Donath, H. Möhwald: SANS measurements of polyelectrolyte multilayer thickness on colloidal templates. Langmuir 18 (2002) 7861-7866
  • V. N. Shilov, A. V. Delgado, F. Gonzalez-Caballero, C. Große, E. Donath: Suspensions in an alternating external electric field: Dielectric and electrorotation spectroscopies. In: Interfacial Electrokinetics and Electrophoresis, (Ed. A. V. Delgado), 2001, Marcel Dekker New York, pp. 329-367
  • R. Georgieva, S. Moya, M. Hin, R. Mitlöhner, E. Donath, H. Kiesewetter, H. Möhwald, H. Bäumler: Permeation of macromolecules into polyelectrolyte microcapsules. Biomacromolecules 3 (2002) 517-524
  • Z. Dai, L. Dähne, E. Donath, H. Möhwald: Mimicking photosynthetic two-step energy transfer in Cyanine triads assembled into capsules. Langmuir 18 (2002) 4553-4555
  • C. Gao, S. Moya, E. Donath, H. Möhwald: Melamine formaldehyde core decomposition as the key step controlling capsule integrity: Optimizing the polyelectrolyte capsule fabrication. Macromol. Chem. Phys. 203 (2002) 953-960
  • Z. Dai, H. Zastrow, S. Leporatti, E. Donath, H. Möhwald, B. Peng: Synthesis and encapsulation of N,N,N´,N´- Tetrakis[p-di(n-butyl) aminophenyl]-p-benzoquinone-bis(imonium hexafluoroantimonate). J. Disper. Sci. Technol. 23 (2002) 555-562
  • G. Ibarz, L. Dähne, E. Donath, H. Möhwald: Resealing of polyelectrolyte capsules after core removal. Macromol. Rapid Commun. 23 (2002) 474-478
  • G. Berth, A. Voigt, H. Dautzenberg, E. Donath, H. Möhwald: Polyelectrolyte complexes and layer-by-layer capsules from chitosan/chitosan sulfate. Biomacromolecules 3 (2002) 579-590
  • G. B. Sukhorukov, A. S. Susha, S. Davies, S. Leporatti, E. Donath, J. Hartmann, H. Möhwald: Precipitation of inorganic salts inside hollow micrometer-sized polyelectrolyte shells. J. Coll. Interface Sci. 247 (2002) 251-254
  • D. Jung, J.-D. Hong, A. Voigt, S. Leporatti, L. Dähne, E. Donath, H. Möhwald: Photochromic hollow shells. Photoizomerization of benzene polyionene in solution and in multilayer assemblies on planar and spherical surfaces. Colloids & Surfaces 198-200 (2002) 483-489.
  • A. A. Antipov, G. B. Sukhorukov, S. Leporatti, I. L. Radtchenko, E. Donath, H. Möhwald: Polyelectrolyte Multilayer Capsule Permeability Control. Colloids and Surfaces A 198-200 (2002) 535-541.
  • C. Peyratout, E. Donath, L. Dähne: Investigation of pseudoisocyanine aggregates formed on polystyrenesulfonate. Photochem. Photobiol. Sci. 1 (2002) 87-91
  • C. Peyratout, E. Donath, L. Dähne: Electrostatic interactions of cationic dyes with negatively charged polyelectrolytes in aqueous solution. J. Photochem. Photobiol. A 142 (2001) 51-57
  • X. Qiu, E. Donath, H. Möhwald: Permeability of Ibuprofen in various polyelectrolyte multilayers. Macromol. Mat. Eng. 286 (2001) 591-597
  • N. G. Balabushevitch, G. B. Sukhorukov, N. A. Moroz, D. V. Volodkin, N. L. Larionova, E. Donath, H. Möhwald: Encapsulation of proteins by layer-by-layer adsorption of polyelectrolytes onto protein aggregates: Factors regulating the protein release.Biotechn. Bioeng. 76 (2001) 207-213
  • X. Qiu, S. Leporatti, E. Donath, H. Möhwald: Studies on the drug release properties of polysaccharide multilayer encapsulated ibuprofen microparticles. Langmuir 17 (2001) 5357-5380
  • C. Gao, S. Moya, H. Lichtenfeld, A. Casoli, H. Fiedler, E. Donath, H. Möhwald: The decomposition process of melamine formaldehyde cores - the key step in the fabrication of ultrathin polyelectrolyte multilayer capsules. Macromol. Mater. Eng. 286 (2001) 355-361
  • G. Ibarz, L. Dähne, E. Donath, H. Möhwald: Smart micro- and nanocontainers for storage, transport and release. Adv. Mater. 13 (2001) 1324-1327
  • L. Dähne, S. Leporatti, E. Donath. H. Möhwald: Fabrication of micro reaction cages with tailored properties. J. Amer. Chem. Soc. 123 (2001) 5431-5436
  • Z. Dai, A. Voigt, E. Donath, H. Möhwald: Novel encapsulated functional dye particles based on alternately adsorbed multi-layers of active oppositely charged macromolecular species. Macromol. Rapid Commun. 22 (2001) 756-762
  • Z. Dai, A. Voigt, S. Leporatti, E. Donath, H. Möhwald: Layer-by-layer self-assembly of polyelectrolyte and low molecular weight species into capsules. Adv. Mater. 13 (2001)1339-1342
  • H. Möhwald, H. Lichtenfeld, S. Moya, A. Voigt, G. Sukhorukov, S. Leporatti, L. Dähne, A. Antipov, C. Y. Gao, E. Donath: From polymeric films to nanocapsules. Stud. Surf. Sci. Catal. 132 (2001) 485-490
  • C. Gao, S. Leporatti, S. Moya, E. Donath, H. Möhwald: Stability and Mechanical Properties of polyelectrolyte capsules obtained by stepwise assembly of Poly(styrenesulfonate sodium salt) and Poly(diallyldimethyl Ammonium Chloride) onto Melamin resin particles. Langmuir 17 (2001) 3491-3495
  • I. Estrela-Lopis, G.Brezesinski, H. Möhwald: Dipalmitoyl-phosphatidyl-choline/phospholipase D interactions investigated with polarization-modulated infrared reflection absorption spectroscopy. Biophysical Journal. 80 (2001) 749-754
  • S. Moya, L. Dähne, A. Voigt, S. Leporatti, E. Donath, H. Möhwald: Polyelectrolyte multilayer capsules templated on biological cells: core oxidation influences layer chemistry. Colloids & Surfaces 183-185 (2001) 27-40
  • B. Neu, A. Voigt, R. Mitlöhner, S. Leporatti, C.Y. Gao, E. Donath, H. Kiesewetter, H. Möhwald, H.J. Meiselman, H. Bäumler: Biological cells as template for hollow microcapsules. J. Microencapsul. 18 (2001) 385-395
  • A. A. Antipov, B. B. Sukhorukov, E. Donath, H. Möhwald: Sustained release properties of polyelectrolyte multilayers capsules. J. Phys. Chem. B 105 (2001) 2281-2284
  • A. Voigt, N. Buske, G. B. Sukhorukov, A. A. Antipov, S. Leporatti, H. Lichtenfeld, H. Bäumler, E. Donath, H. Möhwald: Novel polyelectrolyte multilayer micro-and nanocapsules as magnetic carriers. J. Magn. Mat. Magn. 225 (2001) 59-66
  • C. Gao, E. Donath, S. Moya, V. Dudnik, H. Möhwald: Elasticity of hollow polyelectrolyte capsules prepared by the layer-by-layer technique. Eur. Phys. J. E 5 (2001) 21-27
  • G. B. Sukhorukov, A. A. Antipov, A. Voigt, E. Donath, H. Möhwald: pH-controlled macromolecule encapsulation in and release from polyelectrolyte multilayer capsules. Macromol. Rapid. Commun. 22 (2001) 44-46
  • S. Leporatti, C. Gao, A. Voigt, E. Donath, H. Möhwald: Shrinking of ultrathin polyelectrolyte multilayer capsules upon annealing: A confocal laser scanning microscopy and scanning force microscopy study. Eur. Phys. J. E 5 (2001)13-20
  • A. Voigt, E. Donath, H. Möhwald: Preparation of microcapsules of strong polyelectrolyte couples by one-step complex surface precipitation. Macromol. Mater. Eng. 282 (2000) 13-16
  • I. L Radtchenko, G. B. Sukhorukov, S. Leporatti, G. B. Khomutov, E. Donath, H. Möhwald: Assembly of alternated multivalent ion/polyelectrolyte layers on colloidal particles. Stability of the multilayers and encapsulation of macromolecules into polyelectrolyte capsules. J. Coll. Interface Sci. 230 (2000) 272-280
  • R. Georgieva, S. Moya, C. Reichle, S. Leporatti, B. Neu, H. Bäumler, E. Donath, H. Möhwald: Conductance and capacitance of polyelectrolyte and lipid-polyelectrolyte composite capsules as measured by electrorotation. Langmuir 16 (2000) 7075-7081
  • C. Gao, S. Leporatti, E. Donath, H. Möhwald: Surface texture of Poly(styrenesulfonate sodium salt) and Poly(diallyldimethyl ammonium chloride) micron-sized multilayer capsules: A scanning force and confocal microscopy study. J. Phys. Chem. B 104 (2000) 7144-7149
  • S. Moya, E. Donath, G. B. Sukhorukov, M. Auch, H. Bäumler, H. Lichtenfeld, H. Möhwald: Lipid coating on polyelectrolyte surface modified colloidal particles and polyelectrolyte capsules. Macromolecules 33 (2000) 4538-4544
  • S. Leporatti, A. Voigt, R. Mitlöhner, G. B. Sukhorukov, E. Donath, H. Möhwald: Scanning force microscopy investigation of polyelectrolyte nano- and microcapsule wall texture. Langmuir 16 (2000) 4059-4063
  • G. B. Sukhorukov, L. Dähne, J. Hartmann, E. Donath, H. Möhwald: Controlled precipitation of dyes into hollow polyelectrolyte capsules based on colloids and biocolloids. Adv. Mater. 12 (2000) 112-115
  • G. B. Sukhorukov, E. Donath, S. Moya, A. S. Susha, A. Voigt, J. Hartmann, H. Möhwald: Microencapsulation by means of step-wise adsorption of polyelectrolytes. J. Microencapsulation, 17 (2000) 177-185
  • S. Leporatti, G. Brezesinski, H. Mohwald: Coexistence of phases in monolayers of branched-chain phospholipids investigated by scanning force microscopy Colloids & Surfaces 161 (2000) 159-171
  • A. Holzwarth, S. Leporatti, H. Riegler: Molecular ordering and domain morphology of molecularly thin triacontane films at SiO2/air interfaces. Europhysics Letters., 52 (2000) 653-659
  • I. Estrela-Lopis, G. Brezesinski, H. Mohwald: Influence of model membrane structure on phospholipase D activity. Physical Chemistry Chemical Physics., 2 (2000) 4600-4604
  • A. Voigt, H. Lichtenfeld, H. Zastrow, E. Donath, H. Bäumler, H. Möhwald: Membrane filtration for microencapsulation and microcapsules fabrication by layer-by-layer polyelectrolyte adsorption. Ind. Eng. Chem. Res. 38 (1999) 4037-4043
  • G. B. Sukhorukov, M. Brumen, E. Donath, H. Möhwald: Hollow Polyelectrolyte Shells: Exclusion of Polymers and Donnan Equilibrium. J. Phys. Chem. B 31 (1999) 6434-6440
  • S. Moya, G. B. Sukhorukov, M. Auch, E. Donath and H. Möhwald: Microencapsulation of Organic Solvents in Polyelectrolyte Multilayer Micron-sized Shells. J. Colloid Interface Sci. 216 (1999) 297-302
  • E. Donath, G. B. Sukhorukov, H. Möhwald: Polyelektrolytkapseln im Submikrometer- und Mikrometerbereich. Herstellung und Eigenschaften. Nachr. Chem. Tech. Lab. 47 (1999) 400-405
  • F. Caruso, H. Lichtenfeld, E. Donath, H. Möhwald: Investigation of Electrostatic Interactions in Polyelectrolyte Multilayer Films: Binding of Anionic Fluorescent Probes to Layers Assembled onto Colloids. Macromolecules 32 (1999) 2317-2328
  • H. Bäumler, B. Neu, S. Iovtchev, A. Budde, H. Kiesewetter, R. Latza, E. Donath: Electroosmosis and polymer depletion layers near surface conducting particles are detectable by low frequency electrorotation. Colloids Surfaces A: Physicochem. Eng. Aspects 149 (1999) 389-396
  • H. Möhwald, H. Lichtenfeld, S. Moya, A. Voigt, H. Bäumler, G. Soukhorukov, F. Caruso, E. Donath: From polymeric films to nanoreactors. Macromol. Symp.145 (1999) 75-81
  • H. Bäumler, B. Neu, E. Donath, H. Kiesewetter: Basic phenomena of red blood cell rouleaux formation. Biorheology. 36 (1999) 439-442
  • C. DeWolf, S. Leporatti, C. Kirsch, R. Klinger, G. Brezesinski: Phase separation in phosphatidylinositol/phosphatidylcholine mixed monolayers. Chemistry & Physics of Lipids 97 (1999) 129-138
  • E. Donath, G. B. Sukhorukov, F. Caruso, S. A. Davis, H. Möhwald: Novel hollow polymer shells by colloid-templated assembly of polyelectrolytes. Angew. Chem. Int. Ed. 37 (1998) 2202-2205, Angew. Chem. 110 (1998) 2324-2327
  • F. Caruso, E. Donath, H. Möhwald, R. Georgieva: Fluorescence studies of the binding of anionic derivatives of pyrene and fluorescein to cationic polyelectrolytes in aqueous solution. Macromolecules 31 (1998) 7365-7377
  • G. B. Sukhorukov, E. Donath, S. Davies, H. Lichtenfeld, F. Caruso, V. I. Popov, H. Möhwald: Step-wise polyelectrolyte assembly on particle surfaces - A novel approach to colloid design. Polym. Adv. Technol. 9 (1998) 759-767
  • B. Neu, R.Georgieva, H. Bäumler, N. V. Shilov, E. Knippel, E., Donath: Low- frequency dispersion of surface conducting particles as measured by means of electrorotation. Colloids and Surfaces A 140 (1998) 325-332
  • F. Caruso, E. Donath, H. Möhwald: Influence of Polyelectrolyte Multilayer Coatings on Förster Resonance Energy Transfer between 6-Carboxyfluorescein and Rhodamine B-Labelled Particles in Aqueous Solutions. J. Phys. Chem. B 102 (1998) 2011-2016
  • R. Georgieva, B. Neu, V. M. Shilov, E. Knippel, A. Budde, R. Latza, E. Donath, H. Kiesewetter, H. Bäumler: Low Frequency Electrorotation of Fixed Red Blood Cells. Biophys. J. 74 (1998), 2114-2120.
  • G. B. Sukhorukov, E. Donath, H. Lichtenfeld, E. Knippel, M. Knippel, A. Budde, H. Möhwald: Layer-by-Layer Self Assembly of Polyelectrolytes on Colloidal Particles. Colloids Surfaces A 137 (1998) 253 - 266
  • S. Leporatti, F.Bringezu, G. Brezesinski, H. Mohwald: Condensed phases of branched-chain phospholipid monolayers investigated by scanning force microscopy. Langmuir. 14 (1998) 7503-7510
  • E. Donath, D. Walther, V. N. Shilov, E. Knippel, A. Budde, K. Lowack, C. A. Helm, H. Möhwald: Nonlinear Hairy Layer Theory of Electrophoretic Fingerprinting Applied to Consecutive Layer by Layer Polyelectrolyte Adsorption onto Charged Polystyrene Latex Particles. Langmuir 13 (1997) 5294 - 5305