This thesis is focused on the design and development of an approach, allowing the fabrication of biocompatible/biodegradable self-rolled polymer tubes, which are sensitive to stimuli at physiological conditions, can be homogenously filled with cells and are able to self-assemble into a complex 3D construct with uniaxially aligned pores. These constructs are aimed to recreate the microstructure of tissues with structural anisotropy, such as of muscles and bones. The approach consists of two steps of self-assembly. As a first step, cells are adsorbed on the top of an unfolded bilayer; triggered rolling results in a parallel encapsulation of cells inside the tubes. As a second step, the formed self-rolled tubes with encapsulated cells can be assembled in a uniaxial tubular scaffold. Three polymer systems were designed and investigated in the present work in order to allow triggered folding of the bilayer. These systems allow either reversible or irreversible tube formation. The possibility to encapsulate microobjects inside self-rolled polymer tubes was demonstrated on the example of silica particles, yeast cells and mammalian cells. At conditions when bilayer film is unfolded, particles or cells were deposited from their aqueous dispersion on the top of bilayer. An appropriate change of conditions triggers folding of the bilayer and results in encapsulation of particles or cells inside the tubes. One way swelling of an active polymer allows irreversible encapsulation of cells in a way that tubes do not unroll and cells cannot escape. It was demonstrated that encapsulated cells can proliferate and divide inside the tubes for a long period of time. Since used polymers are optically transparent, encapsulated cells can be easily observed using optical and fluorescent microscopy. Reversible swelling of an active polymer provides the possibility to release encapsulated objects. It was demonstrated that in aqueous media microtubes possessing small amount of negatively charged groups on external walls self-assemble in the presence of oppositely charged microparticles that results in a formation of 3D constructs. In obtained aggregates tubes and therefore pores were well-aligned and the orientation degree was extremely high. Moreover, the approach allows the design of porous materials with complex architectures formed by tubes of different sorts. The assembly of cell-laden microtubes results in a formation of uniaxial tubular scaffold homogeneously filled with cells. The results presented in this work demonstrate that the proposed approach is of practical interest for biotechnological applications. Self-rolled tubes can be filled with cells during their folding providing the desired homogeneity of filling. Individual tubes of different diameters could be used to investigate cell behaviour in confinement in conditions of structural anisotropy as well as to mimic blood vessels. Due to their directionality tubes could be used to guide the growth of cells that is of interest for regeneration of neuronal tissue. Reversibly foldable films allow triggered capture and release of the cells that could be implemented for controlled cell delivery. In perspective, self-assembled 3D constructs with aligned pores could be used for bottom-up engineering of the scaffolds, mimicking such tissues as cortical bone and skeletal muscle, which are characterized by repeating longitudinal units. Such constructs can be also considered as a good alternative of traditional 2D flat cell culture.

This thesis is focused on the design and development of an approach, allowing the fabrication of biocompatible/biodegradable self-rolled polymer tubes, which are sensitive to stimuli at physiological conditions, can be homogenously filled with cells and are able to self-assemble into a complex 3D construct with uniaxially aligned pores. These constructs are aimed to recreate the microstructure of tissues with structural anisotropy, such as of muscles and bones. The approach consists of two steps of self-assembly. As a first step, cells are adsorbed on the top of an unfolded bilayer; triggered rolling results in a parallel encapsulation of cells inside the tubes. As a second step, the formed self-rolled tubes with encapsulated cells can be assembled in a uniaxial tubular scaffold. Three polymer systems were designed and investigated in the present work in order to allow triggered folding of the bilayer. These systems allow either reversible or irreversible tube formation. The possibility to encapsulate microobjects inside self-rolled polymer tubes was demonstrated on the example of silica particles, yeast cells and mammalian cells. At conditions when bilayer film is unfolded, particles or cells were deposited from their aqueous dispersion on the top of bilayer. An appropriate change of conditions triggers folding of the bilayer and results in encapsulation of particles or cells inside the tubes. One way swelling of an active polymer allows irreversible encapsulation of cells in a way that tubes do not unroll and cells cannot escape. It was demonstrated that encapsulated cells can proliferate and divide inside the tubes for a long period of time. Since used polymers are optically transparent, encapsulated cells can be easily observed using optical and fluorescent microscopy. Reversible swelling of an active polymer provides the possibility to release encapsulated objects. It was demonstrated that in aqueous media microtubes possessing small amount of negatively charged groups on external walls self-assemble in the presence of oppositely charged microparticles that results in a formation of 3D constructs. In obtained aggregates tubes and therefore pores were well-aligned and the orientation degree was extremely high. Moreover, the approach allows the design of porous materials with complex architectures formed by tubes of different sorts. The assembly of cell-laden microtubes results in a formation of uniaxial tubular scaffold homogeneously filled with cells. The results presented in this work demonstrate that the proposed approach is of practical interest for biotechnological applications. Self-rolled tubes can be filled with cells during their folding providing the desired homogeneity of filling. Individual tubes of different diameters could be used to investigate cell behaviour in confinement in conditions of structural anisotropy as well as to mimic blood vessels. Due to their directionality tubes could be used to guide the growth of cells that is of interest for regeneration of neuronal tissue. Reversibly foldable films allow triggered capture and release of the cells that could be implemented for controlled cell delivery. In perspective, self-assembled 3D constructs with aligned pores could be used for bottom-up engineering of the scaffolds, mimicking such tissues as cortical bone and skeletal muscle, which are characterized by repeating longitudinal units. Such constructs can be also considered as a good alternative of traditional 2D flat cell culture.

Die Menschheit steht vor der großen Herausforderung der Energieversorgung des 21. Jahrhundert. Nirgendwo ist diese noch dringlicher geworden als im Bereich der Energiespeicherung und Umwandlung. Konventionelle Energie kommt hauptsächlich aus fossilen Brennstoffen, die auf der Erde nur begrenzt vorhanden sind, und hat zu einer starken Belastung der Umwelt geführt. Zusätzlich nimmt der Energieverbrauch weiter zu, insbesondere durch die rasante Verbreitung von Fahrzeugen und verschiedener Kundenelektronik wie PCs und Mobiltelefone. Alternative Energiequellen sollten vor einer Energiekrise entwickelt werden. Die Gewinnung erneuerbarer Energie aus Sonne und Wind sind auf jeden Fall sehr wichtig, aber diese Energien sind oft nicht gleichmäßig und andauernd vorhanden. Energiespeichervorrichtungen sind daher von großer Bedeutung, weil sie für eine Stabilisierung der umgewandelten Energie sorgen. Darüber hinaus ist es eine enttäuschende Tatsache, dass der Akku eines Smartphones jeglichen Herstellers heute gerade einen Tag lang ausreicht, und die Nutzer einen zusätzlichen Akku zur Hand haben müssen. Die tragbare Elektronik benötigt dringend Hochleistungsenergiespeicher mit höherer Energiedichte. Der erste Teil der vorliegenden Arbeit beinhaltet Lithium-Ionen-Batterien unter Verwendung von einzelnen aufgerollten Siliziumstrukturen als Anoden, die durch nanotechnologische Methoden hergestellt werden. Eine Lab-on-Chip-Plattform wird für die Untersuchung der elektrochemischen Kinetik, der elektrischen Eigenschaften und die von dem Lithium verursachten strukturellen Veränderungen von einzelnen Siliziumrohrchen als Anoden in einer Lithium-Ionen-Batterie vorgestellt. In dem zweiten Teil wird ein neues Design und die Herstellung von flexiblen on-Chip, Festkörper Mikrosuperkondensatoren auf Basis von MnOx/Au-Multischichten vorgestellt, die mit aktueller Mikroelektronik kompatibel sind. Der Mikrosuperkondensator erzielt eine maximale Energiedichte von 1,75 mW h cm-3 und eine maximale Leistungsdichte von 3,44 W cm-3. Weiterhin wird ein flexibler und faserartig verwebter Superkondensator mit einem Cu-Draht als Substrat vorgestellt. Diese Dissertation wurde im Rahmen des Forschungsprojekts GRK 1215 "Rolled-up Nanotechnologie für on-Chip Energiespeicherung" 2010-2013, finanziell unterstützt von der International Research Training Group (IRTG), und dem PAKT Projekt "Elektrochemische Energiespeicherung in autonomen Systemen, no. 49004401" 2013-2014, angefertigt. Das Ziel der Projekte war die Entwicklung von fortschrittlichen Energiespeichermaterialien für die nächste Generation von Akkus und von flexiblen Superkondensatoren, um das Problem der Energiespeicherung zu addressieren. Hier bedanke ich mich sehr, dass IRTG mir die Möglichkeit angebotet hat, die Forschung in Deutschland stattzufinden. / Human beings are facing the grand energy challenge in the 21st century. Nowhere has this become more urgent than in the area of energy storage and conversion. Conventional energy is based on fossil fuels which are limited on the earth, and has caused extensive environmental pollutions. Additionally, the consumptions of energy are still increasing, especially with the rapid proliferation of vehicles and various consumer electronics like PCs and cell phones. We cannot rely on the earth’s limited legacy forever. Alternative energy resources should be developed before an energy crisis. The developments of renewable conversion energy from solar and wind are very important but these energies are often not even and continuous. Therefore, energy storage devices are of significant importance since they are the one stabilizing the converted energy. In addition, it is a disappointing fact that nowadays a smart phone, no matter of which brand, runs out of power in one day, and users have to carry an extra mobile power pack. Portable electronics demands urgently high-performance energy storage devices with higher energy density. The first part of this work involves lithium-ion micro-batteries utilizing single silicon rolled-up tubes as anodes, which are fabricated by the rolled-up nanotechnology approach. A lab-on-chip electrochemical device platform is presented for probing the electrochemical kinetics, electrical properties and lithium-driven structural changes of a single silicon rolled-up tube as an anode in lithium ion batteries. The second part introduces the new design and fabrication of on chip, all solid-state and flexible micro-supercapacitors based on MnOx/Au multilayers, which are compatible with current microelectronics. The micro-supercapacitor exhibits a maximum energy density of 1.75 mW h cm-3 and a maximum power density of 3.44 W cm-3. Furthermore, a flexible and weavable fiber-like supercapacitor is also demonstrated using Cu wire as substrate. This dissertation was written based on the research project supported by the International Research Training Group (IRTG) GRK 1215 "Rolled-up nanotech for on-chip energy storage" from the year 2010 to 2013 and PAKT project "Electrochemical energy storage in autonomous systems, no. 49004401" from 2013 to 2014. The aim of the projects was to design advanced energy storage materials for next-generation rechargeable batteries and flexible supercapacitors in order to address the energy issue. Here, I am deeply indebted to IRTG for giving me an opportunity to carry out the research project in Germany. September 2014, IFW Dresden, Germany Wenping Si

Die Menschheit steht vor der großen Herausforderung der Energieversorgung des 21. Jahrhundert. Nirgendwo ist diese noch dringlicher geworden als im Bereich der Energiespeicherung und Umwandlung. Konventionelle Energie kommt hauptsächlich aus fossilen Brennstoffen, die auf der Erde nur begrenzt vorhanden sind, und hat zu einer starken Belastung der Umwelt geführt. Zusätzlich nimmt der Energieverbrauch weiter zu, insbesondere durch die rasante Verbreitung von Fahrzeugen und verschiedener Kundenelektronik wie PCs und Mobiltelefone. Alternative Energiequellen sollten vor einer Energiekrise entwickelt werden. Die Gewinnung erneuerbarer Energie aus Sonne und Wind sind auf jeden Fall sehr wichtig, aber diese Energien sind oft nicht gleichmäßig und andauernd vorhanden. Energiespeichervorrichtungen sind daher von großer Bedeutung, weil sie für eine Stabilisierung der umgewandelten Energie sorgen. Darüber hinaus ist es eine enttäuschende Tatsache, dass der Akku eines Smartphones jeglichen Herstellers heute gerade einen Tag lang ausreicht, und die Nutzer einen zusätzlichen Akku zur Hand haben müssen. Die tragbare Elektronik benötigt dringend Hochleistungsenergiespeicher mit höherer Energiedichte. Der erste Teil der vorliegenden Arbeit beinhaltet Lithium-Ionen-Batterien unter Verwendung von einzelnen aufgerollten Siliziumstrukturen als Anoden, die durch nanotechnologische Methoden hergestellt werden. Eine Lab-on-Chip-Plattform wird für die Untersuchung der elektrochemischen Kinetik, der elektrischen Eigenschaften und die von dem Lithium verursachten strukturellen Veränderungen von einzelnen Siliziumrohrchen als Anoden in einer Lithium-Ionen-Batterie vorgestellt. In dem zweiten Teil wird ein neues Design und die Herstellung von flexiblen on-Chip, Festkörper Mikrosuperkondensatoren auf Basis von MnOx/Au-Multischichten vorgestellt, die mit aktueller Mikroelektronik kompatibel sind. Der Mikrosuperkondensator erzielt eine maximale Energiedichte von 1,75 mW h cm-3 und eine maximale Leistungsdichte von 3,44 W cm-3. Weiterhin wird ein flexibler und faserartig verwebter Superkondensator mit einem Cu-Draht als Substrat vorgestellt. Diese Dissertation wurde im Rahmen des Forschungsprojekts GRK 1215 "Rolled-up Nanotechnologie für on-Chip Energiespeicherung" 2010-2013, finanziell unterstützt von der International Research Training Group (IRTG), und dem PAKT Projekt "Elektrochemische Energiespeicherung in autonomen Systemen, no. 49004401" 2013-2014, angefertigt. Das Ziel der Projekte war die Entwicklung von fortschrittlichen Energiespeichermaterialien für die nächste Generation von Akkus und von flexiblen Superkondensatoren, um das Problem der Energiespeicherung zu addressieren. Hier bedanke ich mich sehr, dass IRTG mir die Möglichkeit angebotet hat, die Forschung in Deutschland stattzufinden. / Human beings are facing the grand energy challenge in the 21st century. Nowhere has this become more urgent than in the area of energy storage and conversion. Conventional energy is based on fossil fuels which are limited on the earth, and has caused extensive environmental pollutions. Additionally, the consumptions of energy are still increasing, especially with the rapid proliferation of vehicles and various consumer electronics like PCs and cell phones. We cannot rely on the earth’s limited legacy forever. Alternative energy resources should be developed before an energy crisis. The developments of renewable conversion energy from solar and wind are very important but these energies are often not even and continuous. Therefore, energy storage devices are of significant importance since they are the one stabilizing the converted energy. In addition, it is a disappointing fact that nowadays a smart phone, no matter of which brand, runs out of power in one day, and users have to carry an extra mobile power pack. Portable electronics demands urgently high-performance energy storage devices with higher energy density. The first part of this work involves lithium-ion micro-batteries utilizing single silicon rolled-up tubes as anodes, which are fabricated by the rolled-up nanotechnology approach. A lab-on-chip electrochemical device platform is presented for probing the electrochemical kinetics, electrical properties and lithium-driven structural changes of a single silicon rolled-up tube as an anode in lithium ion batteries. The second part introduces the new design and fabrication of on chip, all solid-state and flexible micro-supercapacitors based on MnOx/Au multilayers, which are compatible with current microelectronics. The micro-supercapacitor exhibits a maximum energy density of 1.75 mW h cm-3 and a maximum power density of 3.44 W cm-3. Furthermore, a flexible and weavable fiber-like supercapacitor is also demonstrated using Cu wire as substrate. This dissertation was written based on the research project supported by the International Research Training Group (IRTG) GRK 1215 "Rolled-up nanotech for on-chip energy storage" from the year 2010 to 2013 and PAKT project "Electrochemical energy storage in autonomous systems, no. 49004401" from 2013 to 2014. The aim of the projects was to design advanced energy storage materials for next-generation rechargeable batteries and flexible supercapacitors in order to address the energy issue. Here, I am deeply indebted to IRTG for giving me an opportunity to carry out the research project in Germany. September 2014, IFW Dresden, Germany Wenping Si