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In this paper, we present the design, development, and characteristics of the novel aerosol mass spectrometer ERICA (ERC Instrument for Chemical composition of Aerosols; ERC – European Research Council) and selected results from the first airborne field deployment. The instrument combines two well-established methods of real-time in situ measurements of fine particle chemical composition. The first method is the laser desorption and ionization technique, or laser ablation technique, for single-particle mass spectrometry (here with a frequency-quadrupled Nd:YAG laser at λ = 266 nm). The second method is a combination of thermal particle desorption, also called flash vaporization, and electron impact ionization (like the Aerodyne aerosol mass spectrometer). The same aerosol sample flow is analyzed using both methods simultaneously, each using time-of-flight mass spectrometry. By means of the laser ablation, single particles are qualitatively analyzed (including the refractory components), while the flash vaporization and electron impact ionization technique provides quantitative information on the non-refractory components (i.e., particulate sulfate, nitrate, ammonia, organics, and chloride) of small particle ensembles. These techniques are implemented in two consecutive instrument stages within a common sample inlet and a common vacuum chamber. At its front end, the sample air containing the aerosol particles is continuously injected via an aerodynamic lens. All particles which are not ablated by the Nd:YAG laser in the first instrument stage continue their flight until they reach the second instrument stage and impact on the vaporizer surface (operated at 600 ∘C). The ERICA is capable of detecting single particles with vacuum aerodynamic diameters (dva) between ∼ 180 and 3170 nm (d50 cutoff). The chemical characterization of single particles is achieved by recording cations and anions with a bipolar time-of-flight mass spectrometer. For the measurement of non-refractory components, the particle size range extends from approximately 120 to 3500 nm (d50 cutoff; dva), and the cations are detected with a time-of-flight mass spectrometer. The compact dimensions of the instrument are such that the ERICA can be deployed on aircraft, at ground stations, or in mobile laboratories. To characterize the focused detection lasers, the ablation laser, and the particle beam, comprehensive laboratory experiments were conducted. During its first deployments the instrument was fully automated and operated during 11 research flights on the Russian high-altitude research aircraft M-55 Geophysica from ground pressure and temperature to 20 km altitude at 55 hPa and ambient temperatures as low as −86 ∘C. In this paper, we show that the ERICA is capable of measuring reliably under such conditions.

Die Prävalenz von Alkohol in der heutigen Gesellschaft ist unumstritten, wodurch sich vielfältige Fragestellungen ergeben, welche oftmals nicht alleinig durch die Messung einer Blutalkoholkonzentration beantwortet werden können. Aufgrund dessen nahm die Bedeutung von spezifischen Abbauprodukten des Ethanols, auch Alkoholbiomarker genannt, in den letzten Jahren stetig zu, da ein Alkoholkonsum durch deren Messung deutlich länger nachweisbar ist. Dafür ist eine verlässliche und robuste Analytik der verschiedenen Biomarker zur Beantwortung diverser Fragestellungen, z.B. im Rahmen der Abstinenzkontrolle, unerlässlich. Aus diesem Grund war das Ziel dieser Arbeit die Entwicklung, Etablierung, Validierung und Anwendung einer neuartigen und spezifischen Multimethode zum Nachweis diverser Alkoholbiomarker wie Ethylglucuronid, Ethylsulfat, N-Acetyltaurin und 16:0/18:1 Phosphatidylethanol. Nach einer erfolgreichen Methodenentwicklung und -validierung entsprechend der Richtlinien der GTFCh konnten alle vier Biomarker mit einer sehr guten Intensität und Reproduzierbarkeit qualitativ nachgewiesen und quantitativ bestimmt werden. Anschließend wurde die Methode im Rahmen verschiedener Studien angewendet, um forensisch und analytisch verwertbare Ergebnisse zu gewinnen. Es ergaben sich Anwendungsgebiete aus der Leichentoxikologie, Pharmakokinetik sowie der klinischen Diagnostik. Zusätzlich wurde geklärt, inwieweit eine Anwendung von NAcT als Alkoholbiomarker sinnvoll ist, wobei die erhaltenen Ergebnisse eine Anwendung nicht unterstützen. Um die Eignung der Methode zur Untersuchung von postmortalem Blut zu testen, wurden 31 Proben gemessen, in denen zuvor hohe Blutalkoholkonzentrationen nachgewiesen werden konnten. Die hierdurch ermittelten Ergebnisse bestätigten die Anwendbarkeit der Methode für postmortales Probenmaterial. Aufgrund der Bestimmung mehrerer Alkoholbiomarker kann eine Alkoholisierung vor dem Tod von einer durch postmortal gebildetes EtOH verursachten Verfälschung der BAK unterschieden werden. Durch die parallele Bestimmung der drei Alkoholbiomarker Ethylglucuronid, Ethylsulfat und 16:0/18:1 Phosphatidylethanol steigt die Aussagekraft der erhobenen Ergebnisse. Zusätzlich wurden zwei Trinkversuche am Institut für Rechts- und Verkehrsmedizin in Heidelberg durchgeführt, in welchem Probanden eine individuelle Alkoholmenge aufgenommen haben, um eine vorgegebene Blutalkoholkonzentration zu erreichen. Über den ersten Versuchstag und einem Zeitfenster von sieben Tagen wurden in definierten Abständen Blut- und Urinproben erhoben, um die Verlässlichkeit der entwickelten Multimethode und die Pharmakokinetiken der einzelnen Biomarker zu untersuchen. Ein weiteres Ziel dieses Studiendesigns war die Ermittlung eines physiologischen Grundwertes für N-Acetyltaurin, da diese Substanz im menschlichen Körper endogen gebildet wird. Es konnte belegt werden, dass N-Acetyltaurin den Ansprüchen eines Biomarkers zum Nachweis eines Alkoholkonsums nicht gerecht werden kann, da die individuellen Schwankungen zu stark sind und keine nachvollziehbare Pharmakokinetik aufgezeigt werden konnte. Im Gegensatz hierzu konnte für die bereits etablierten Biomarker Ethylglucuronid und Ethylsulfat erneut bestätigt werden, dass diese in der Matrix Urin eine entsprechend gute Möglichkeit bieten, in Abhängigkeit von der aufgenommenen Dosis, einen vorangegangen Alkoholkonsum verlässlich nachzuweisen. Der Biomarker 16:0/18:1 Phosphatidylethanol, welcher nur in Vollblut nachgewiesen werden kann, deckt ein noch größeres Nachweisfenster ab und kann auch ein einmaliges, länger zurückliegendes Trinkgeschehen belegen. Dieser Biomarker ist bisher in der forensischtoxikologischen Analytik in Deutschland zum Nachweis einer Alkoholabstinenz nicht etabliert. Mittels der im Rahmen dieser Arbeit validierten Methode ist es nun möglich, den Biomarker 16:0/18:1 Phosphatidylethanol im Rahmen des Abstinenzprogrammes am IRVM analytisch zu bestimmen und in die Beurteilung mit einfließen zu lassen. In einem weiteren Projekt wurde die neu entwickelte Methode zum Nachweis der drei anwendbaren Biomarker im Entzugskontext verwendet. Das Kollektiv bestand aus Blutproben, die zu Beginn und Ende eines Entzugsaufenthaltes im Krankenhaus Salem abgenommen und auf ihre Biomarkerkonzentrationen untersucht wurden. Dabei konnte gezeigt werden, dass Ethylglucuronid und Ethylsulfat innerhalb der Klinikaufenthalte unabhängig von dem Parameter der Lebersteifigkeit im Blut komplett abgebaut wurden. Da Phosphatidylethanol in den Erythrozytenmembranen akkumuliert und nur sehr langsam abgebaut wird, war dieser Biomarker auch zum Ende des Entzugs bei nahezu allen Patienten nachweisbar. Im Falle dieses Alkoholbiomarkers konnte durch einen Kruskal-Wallis-Test gezeigt werden, dass es keinen Zusammenhang zwischen dem Abbau und der Lebersteifigkeit gab. Zusammenfassend lässt sich feststellen, dass die in dieser Arbeit entwickelte analytische Multimethode vielfältige Möglichkeiten bietet, um ein sehr breites Spektrum von Fragestellungen im Bereich der Forensischen Toxikologie beantworten zu können.

We report on the developments that enabled the field deployment of a fully-automated aerosol mass spectrometer, specially designed for high-altitude measurements on unpressurised aircraft. The merits of the two main categories of real-time aerosol mass spectrometry, i.e. (a) single particle laser desorption and ionization, and (b) continuous thermal desorption / electron impact ionization of aerosols, have been integrated into one compact apparatus with the aim to perform in-situ real-time analysis of aerosol chemical composition. The demonstrated instrument, named ERICA (European Research council Instrument for the Chemical composition of Aerosols), operated successfully aboard the high-altitude research aircraft M-55 Geophysica at altitudes up to 20 km, while being exposed to ambient conditions of very low atmospheric pressure and temperature. A primary goal of those field deployments was the in-situ study of the Asian Tropopause Aerosol Layer (ATAL). During 11 research flights, the instrument operated for more than 49 hours and collected chemical composition information of more than 150,000 single particles combined with quantitative chemical composition analysis of aerosol particle ensembles. This paper presents in detail the technical characteristics of the main constituent parts of the instrument, as well as the design considerations for its integration into the aircraft and its autonomous operation in the upper troposphere and lower stratosphere (UT/LS). Additionally, system performance data from the first field deployments of the instrument are presented and discussed, together with exemplary mass spectrometry data collected during those flights.

The extraordinary mechanical and charge transport properties of semiconducting single-walled carbon nanotubes (SWNTs) make them a promising material for solution-processable, flexible and stretchable electronics. Many of these remarkable features are even obtained in randomly-oriented SWNT networks that are compatible with established large-scale thin-film processes based on printing techniques or optical lithography. Given the enormous progress in the purification of solely semiconducting nanotubes as well as in the preparation of SWNT networks with a uniform and defined morphology in recent years, their widespread application as active layers in field-effect transistors (FETs) has become feasible. Likewise, this progress raised subsequent questions of what key parameters determine the charge transport processes across these networks and how they can further be optimized. This thesis investigates charge transport and its limitations in polymer-sorted semiconducting SWNT networks with a focus on the precise nanotube network composition. The employed FET geometry enabled a reproducible and undistorted analysis of composition- and temperature- dependent transport parameters such as the charge carrier mobility. A comparison between nanotube networks with various selected or even precisely defined SWNT species distributions and average tube diameters reveals that additional energy barriers created at the junctions of adjacent nanotubes with different diameters result in inferior transport properties. While the network charge transport was formerly considered to be solely limited by the charge transfer across these inter-nanotube junctions, the results of this work imply that also the transport within each individual SWNT is important. The specific diameter dependence of this intra-nanotube transport can rationalize the substantially higher carrier mobilities observed for large-diameter networks with a certain SWNT bandgap distribution compared to monochiral networks that contain only a single small-diameter nanotube species. These findings suggest that composition optimizations for SWNT network FETs with maximum carrier mobilities should aim at monochiral large-diameter nanotubes. Aside from insights into the underlying transport mechanisms, this work demonstrates a novel approach to intentionally modify charge transport in semiconducting SWNT network FETs by adding photochromic spiropyran compounds to the dielectric layer. The strong impact of the spiropyran and its photoinduced isomerization to merocyanine on the charge carrier mobilities give these transistors the properties of basic optical memory devices. Upon UV illumination the carrier mobilities are severely reduced until their recovery is induced by annealing or illumination with visible light. This implemented light responsiveness illustrates the fundamental suitability of SWNT network FETs for multifunctional applications beyond integrated circuits.

Metal microfibers have a wide range of industrial applications, e.g. as filters, fiber-reinforced composites, electrodes, catalysts, sensors, or magnetic shielding materials. In this project, we modified melt-spinning device and its experimental parameters to fabricate metal microfibers. It was shown for the first time that metal microfibers down to 5 μm could be fabricated using a melt spinning device. The size and circularity of formed fibers could be controlled by experimental parameters.e.g. slit distance to the wheel, chamber pressure, slit size, wheel speed. The mechanism of fiber formation relies on two main steps; i)thin film formation on the rotating wheel ii)spontaneous breaking of the film to smaller widths, dewetting the wheel. It was shown that this process is reproducible and could be used for different classes of materials. e.g. intermetallic alloys, conventional alloys, metal elements and amorphous alloys. The modification of the melt spinning device leads to higher quenching rates up to 108!C/s. The high quenching rate made it possible to make fully amorphous stainless steel fibers for the very first time. Heat-treatment of amorphous stainless steel leads to dual-phase microstructure (nanocrystals embedded together with a glassy phase) which was responsible for its ultra-high hardness value, 14GPa. This value is 7 times higher than the original stainless steel hardness. Thus, the technique opens new possibilities for working with conventional and amorphous alloys e.g. mechanically improved conventional alloy microfibers/ribbons, introducing new alloy microstructures.

In recent years, hydrogels developed to promising tools for biomedical and industrial applications. For biomedical approaches hydrogels, possess the capacity to immobilize and release cells, they offer the desired 3D environment to induce cell specific behaviour or serves as a drug delivery system. Moreover, they can be used for tissue engineering approaches by mimicking the ECM. In this thesis, a novel hybrid double cross-linked hydrogel is presented and designed based on the bottom-up approach of synthetic biology. It consists of simultaneously formed chemical and physical cross-links and made out of two components: (1) thiol functionalized HA (74 kDa) (HA-DTPH) and (2) ionic crosslinker (Cl+). HA-DTPH provides the chemical cross-link by forming disulphide bonds and the ionic cross-linker forms physical cross-links, such as hydrogen bonds and salt bridges. Three different ionic cross-linker were used: (1) deacetylated disaccharide unit of HA (dHA+) (2) charged glucosamine (GluA+) and (3) ammonium chloride (NH4+). These ionic cross-linker were chosen due to their biocompatibility and ability to form physical cross-links, such as hydrogen bonds and salt bridges. The increasing capacity to form hydrogen bonds from NH4+ to dHA+ enabled us to study the influence of the physical cross-link on the hydrogel properties. I could show that the disulphide bond formation was enhanced, by adding an ionic cross-linker and led to the formation of stable hydrogels. Under the same reaction conditions, HA-DTPH without an ionic cross-linker, needed further oxidation with hydrogen peroxide to result in a stable hydrogel (HA-DTPH-Ox.). By varying the degree of thiolation on HA and additionally by varying the type and concentrations of the used ionic cross-linker, the mechanical stiffness, swelling properties and response to external stimuli were tuneable. Varying the degree of modification and used ionic cross-linker enables a specific adjustment of the hydrogels specifically the hydrogel suitable for cell studies with mechanical range of 0.1 Pa to 8 kPa. Furthermore, swelling ratios of HA-DTPH-Cl+ hydrogels are highly influenced by the ionic strength and pH. Remarkably HA- DTPH- dHA+ hydrogels upon incubation in a solution of pH 7 showed a feedback loop swelling behaviour. At the swollen state of the hydrogel, the ionic cross-linker dHA+, leaked out of the hydrogel network, acidified the solution, which resulted in shrinking of the hydrogel. Biological properties like enzymatic degradability showed that the half-live of HA-DTPH-Cl+ hydrogels are increasing with increasing capacity of the ionic cross-linker to form hydrogen bonds. Moreover, due to the absence of any toxic agent during the hydrogel formation the hydrogel system was used for live cell applications such as cell encapsulation or cell adhesion studies. To conclude, a hybrid double cross-linked hydrogel system could be presented, mimicking the ECM, in a minimal model and a critical influence of physical cross-links is observed from results obtained by characterizing the physical and biochemical properties by investigating the gels’ swelling capability, response to environmental changes and sensitivity to hyaluronidases. Depending on the desired biomedical application, these hydrogel systems can be tuned in regards to their stiffness, swelling behavior and degradability enabling applications in 3D tissue engineering, drug delivery and regenerative medicine.

Verbindungen des Phosphors spielen eine Schlüsselrolle als Flammschutzmittel FSM)für Polymere und Coatings, da sie aufgrund der chemischen Vielseitigkeit von Phosphor, aus Gründen der Nachhaltigkeit und nicht zuletzt einer hohen Effektivität auch bei niedrigen Beladungen zunehmend halogenierte FSM substituieren. Das Ziel dieser Dissertation war die Entwicklung neuer phosphorbasierter FSM für Epoxidharze, die über mindestens zwei Phosphoratome mit idealerweise unterschiedlichen Substitutionsmustern verfügen, sodass wichtige Struktur-Eigenschaftsbeziehungen hergestellt werden können. Dazu wurden vor allem Derivate des 9,10-Dihydro-10-oxa-phosphaphenanthren-10-oxids (DOPO), einem wichtigen gasphasenaktiven FSM, dargestellt. Das erste Synthesekonzept beinhaltete zunächst die Darstellung N-phosphorylierter Iminophosphorane mittels Staudinger-Reaktion durch die Umsetzung von Phosphoryla- ziden mit verschiedenen trivalenten Phosphorverbindungen (Phosphine, Phosphonite und Phosphite). Die thermischen Stabilitäten betreffende Untersuchungen bestätigten, dass phosphin-basierte N-phosphorylierte Iminophosphorane wie z.B. DOPO-N=PPh3 thermisch stabiler sind als deren phosphitstämmige Analoga wie z.B. DOPO-N=P(OPh)3. Diese zunehmende thermische Stabilität spiegelt sich in den entsprechenden Winkeln und Abständen der N-phosphorylierten Iminophosphorane wider. Das zweite Synthesekonzept hatte die Erweiterung der Staudinger-Reaktion von DOPO-N3 mit pentavalenten Phosphorverbindungen des Typs RR‘(O)P-H zum Ziel. Mit Hilfe der Röntgenkristallstrukturanalyse wurden den Produkten Imidodiphosphorstrukturen (R2(O)P-NH-P(O)R2) zugewiesen. In einem dritten Synthesekonzept wurden ausgehend vom Vinylphosphonsäuredimethylester (VPADME) und unterschiedlichen P-H-Verbindungen zunächst mittels Phospha-Michael-Addition Phosphonsäureester dargestellt. Diese wurden zu den entsprechenden freien Phosphonsäuren hydrolysiert und anschließend in die korrespondie- renden Melaminsalze überführt. Zur Untersuchung der FSM-Wirkung wurden ausgewählte Verbindungen dieser Stoffklassen in unterschiedliche Epoxidharze eingearbeitet - einem Diglycidylether von Bisphenol A (DGEBA) und einem glycidierten Phenolnovolak (DEN 438) und jeweils mit Dicyandiamid (D) als Härter sowie Fenuron (F) als Beschleuniger ausgehärtet. Dabei wurde die Reaktivität gegenüber der Oxirangruppe eingehend untersucht. Es wurde gezeigt, dass sich alle VPADME-stämmigen ethylenverbrückten Bisphosphorverbindungen, die Iminophosphorane DOPO-N=P(OMe)3 und DOPO-N=P(OPh)3 sowie die Imidodiphosphorverbindung DOPO-NH-DOPO reaktiv in die Epoxidharzmatrix einarbeiten lassen. Alle flammgeschützten Epoxidharze wurden auf ihre Materialeigenschaften und Brennbarkeit untersucht und unter Berücksichtigung der Substitutionsmuster an den Phosphoratomen bewertet. Zusätzlich wurden die Flammschutzmechanismen ausgewählter FSM in DGEBA/D/F und DEN 438/D/F mittels Cone-Kalorimetrie untersucht. Die Flammschutztests ergaben, dass die DOPO-stämmigen N-phosphorylierten Iminophosphorane vor allem in dem Harzsystem DEN 438/D/F einen guten Flammschutz bewirken. Allen voran bewirkte DOPO-N=PPh3 aufgrund seiner primären Gasphasenaktivität in diesem Harzsystem den besten Flammschutz, der sämtliche Referenzverbindungen übertraf. In DGEBA/D/F zeigte der ethylenverbrückte Bisphosphonsäurester (EBBPE) aufgrund seiner primären Aktivität in der kondensierten Phase sehr gute Flammschutzeigenschaften, die denen gängiger Referenzverbindungen entsprechen. Mit dieser Arbeit wurde gezeigt, dass sich phosphororganische Verbindungen, die über mindestens zwei Phosphoratome mit unterschiedlichen Substitutionsmustern verfügen, in einer Eintopfreaktion in guten Ausbeuten herstellbar sind und sehr gute Brandschutzergebnisse in unterschiedlichen Epoxidharzen erzielen.

Thanks to their extremely high mobilities, semiconducting carbon nanotubes (CNTs) are a promising material for high speed electronics. Beyond that, CNT networks are inherently flexible and stretchable and can be processed from dispersions resulting in devices with still remarkable electronic properties. They can fulfill many of the various requirements for novel applications including fast switching speeds and high currents at low drive voltages. Depending on the intended use, one or another device property might be more important. CNT networks, processes, and architectures can be tailored to yield devices that can serve the respective purpose. Highly purified semiconducting CNTs are, however, still rather expensive and direct-write techniques are thus preferred to enable variable designs and reduce manufacturing costs. In this work, aerosol-jet printing is investigated as a deposition technique for CNTs that works with small ink volumes but can also be upscaled by parallelization and integrated into high-throughput roll-to-roll printing processes. After the development of printable inks, it is shown that the printing process itself has no influence on the quality of the CNTs although sonication is used to transfer the ink into an aerosol. The electronic properties of CNT networks incorporated in an established transistor structure exhibit reproducibility comparable to other deposition techniques. Moreover, additive manufacturing enables the deposition of several layers on top of each other to increase the overall film thickness up to optically dense films visible to the naked eye. Field-effect mobilities and on-conductances increase and the hysteresis decreases for thicker films compared to dense but thin networks. Based on these findings, CNT films are printed with a thickness of 50–600 nm and vertical charge transport is demonstrated. These films are subsequently sandwiched between electrodes and electrolyte-gating results in doping of CNT films throughout electrode overlap areas of several hundred µm2. The vertical device architecture decouples the printing accuracy from the critical device dimensions while supporting high currents for a small footprint. A comparison of different printed electrode materials reveals the superior properties of printed metals over mixed (metallic and semiconducting) CNTs. Electrodes based on inkjet-printed gold nanoparticles are additionally used on flexible substrates and stable device performance even after several hundred bending cycles is demonstrated for vertical and lateral CNT network transistors. These all-printed devices are promising for further development of electronic circuits that do not require high operating frequencies but rather flexibility, high-currents, and small footprints.

Tay-Sachs disease (TSD) is an autosomal-recessive genetic disorder which results in the dysfunction of the metabolic enzyme hexosaminidase A (HexA). It leads to severe lysosomal storage of acidic glycosphingolipid, namely ganglioside GM2, and early fatalities for humans with the infantile on-set form. Despite fifty years of research, to date there is no effective treatment beyond palliative care. It was found that mouse models of HexA deficiency display only moderate GM2 accumulation, which was connected with a late onset neuronal phenotype. Therefore neuraminidases were investigated as possible bypass enzymes for the degradation of GM2 and offer a new opportunity for therapeutic approaches in humans. However, to assess the extent of side effects for such a therapeutic bypass, the substrate specificity and ganglioside (GG) turnover has to be defined in detail. This work presents the development of an HILIC based LC MS2 method as well as mass spectrometry imaging (MSI) using DESI (QqQ)MS2 and MALDI TOF to monitor GG pattern changes in mouse brains. The HILIC MS2 analysis of mouse brain tissue with neuraminidase 3 or 4 deficiency in the background of TSD as well as combined knockouts of GG synthesis enzymes revealed an overlapping but distinct substrate processing for the neuraminidases Neu3 and Neu4. MSI of the same tissue samples displayed similar patterns in spatial neural GM2 accumulation that suggest rather a broad distribution of these sialidases in mouse brain. Proposed neuroinflammation and demyelination in mouse brains of TSD led to a modulated HILIC MS2 method with which hexosylceramide isomer separation of GG precursor β-glucosylceramide (β-GlcCer) and prominent myelin sheath component β-galactosylceramide (β-GalCer) was achieved. Decreased levels of β-GalCer as a marker for demyelination in brains of TSD combined with neuraminidase deficiency could not be observed at the age of 6 month. Furthermore, proof of concept study and screening of various WT mouse tissues revealed the adaptability of this method. Even α-anomeric HexCers could be separated from mammalian β-anomers. In contrast to the mentioned β-HexCers, invariant natural killer T cells are activated most effectively when recognizing galactosylceramide with an α-glycosidic linkage appearing on the cell surface receptor CD1d of antigen presenting cells. One natural bacterial source of this compound in contact with our body is Bacteroides fragilis, a bacterial member of the human gut microbiome. This work highlights the detection and separation of α-GalCer(d17:0;h17:0) in B.fragilis and three other bacteria of the human gut microbiome β-HexCers. Very recent preliminary studies indicate the identification of an α-glycosidic GalCer in the mouse microbiome with the proposed structure of BdS α-GalCer(d18:0;h16:0).

Cell adhesion is essential for the formation and functional integrity of tissues and organs in multicellular organisms. In vertebrates, the epithelium is a specialized tissue that maintains a protective barrier around organs. Epithelial cells are attached to the extracellular matrix and form tight connections with each other via E-cadherin mediated multiprotein complexes called adherens junctions (AJs). In this thesis, I present a method for light-induced dissociation of dimerizer-mediated AJs. This is the first optochemical tool which allows to control the formation and disassembly of adhesion complexes inside living cells with high spatiotemporal precision. The applied dimerizers are bifunctional small molecules that combine ligands of self-labeling protein tags like Halo and SNAP tag, via a photocleavable linker. These synthetic molecules induce dimeric complexes of proteins expressed as fusion constructs with the respective self-labelling tag inside living cells. The complexes are efficiently disassembled by cleaving the dimerizers with light. To utilize photocleavable dimerizers in the context of cell adhesion, I first established a covalent-covalent binding dimerizer to ensure mechanical stability against mechanical forces acting on the induced protein complexes. I showed the potential to control the formation of adhesions complexes via retention, recruitment and complementation approaches for different target proteins. For example, I replaced the catenin binding sites on E-cadherin with a Halo tag and coexpressed them with SNAP-tagged a-catenin that was deficient of the b-catenin binding site. The dimerizer-mediated E-cadherin-a-catenin complexes could restore the epithelial phenotype of human epidermoid carcinoma cells (A431 cells) when induced in a-catenin KOs, but not in E-cadherin deficient A431D cells. I could show that the lack of AJ formation in A431D cells is associated with the failure of recruiting b-catenin. In a-catenin KOs -catenin was indirectly recruited to the dimerizer-mediated E-cadherin-a-catenin complex via lateral clustering with endogenous E-cadherin. This in turn led to the formation of AJ complexes, which are the coupling points for the contractile actomyosin network between epithelial cells. Moreover, the a-catenin KO phenotype could be restored upon light induced dissociation of the dimerizer-mediated AJs via exposure to near UV light. When using a 405 nm laser to cleave the dimerizers, I was able to target the AJs between two adjacent cells with subcellular precision or to create patterns of deactivated cell-cell adhesion in epithelial monolayers. Furthermore, I could prove the mechanical functionality of the reconstituted AJs by performing a correlation analysis of collective monolayer migration and traction force microscopy. Herein, I demonstrated the application of photocleavable dimerizers to study the cellular response to AJ assembly and disassembly at different scales of space and time. Photocleavable dimerizers present several advantages for applications in living cells. Since the proteinprotein interaction depends on external addition of the dimerizers and can be reliably abrogated by breaking the molecule, the setup offers two binary switches for the formation of AJ complexes, virtually without any basal activity. Furthermore, the system is bioorthogonal and light is a trigger that allows to dissociate the protein complexes at subcellular and subsecond resolution. The possibility to combine it with specialized imaging techniques like traction force microscopy renders it a powerful tool to study the mechanobiology of AJs and its contribution to processes in epithelial cell layers like cellular jamming and unjamming, collective migration and stress propagation. This new method will help to gain new insights in the dynamic regulation of cell adhesion in fundamental pathophysiological processes like embryonal development, wound healing or cancer metastasis.

Lignin und Lignocellulose haltige Restbiomassen sind vielversprechende Rohstoffe zur Gewinnung von Treibstoffen und Grundstoffen für die chemische Industrie. Bislang konnte dieses große Potential aufgrund fehlender Verfahren allerdings noch nicht abgerufen werden. Im Rahmen dieser Arbeit gelang es jedoch nach dem Vorbild der direkten Verflüssigung von Braunkohle ein Verfahren zu entwickeln, welches erstmals eine effiziente Umwandlung von Lignin und Restbiomassen zu flüssigen Rohstoffen für die Herstellung von Treibstoffen und aromatischen Grundchemikalien ermöglicht. Zur Realisierung einer Parameterstudie und zur Untersuchung des Prozesses wurden Versuchsanlagen im Labormaßstab, sowie im Technischen Maßstab entwickelt und erprobt. Die Hydrogenolyse von technischen Ligninen konnte damit, sowohl im Labormaßstab, als auch in Technikumsmaßstab erfolgreich realisiert werden. Beim Einsatz von technischen Ligninen aus der Papierindustrie konnten die Ausbeuten an organischem Flüssigprodukt auf über 70 m.% optimiert werden. Den größten Einfluss auf die Umsetzung zeigte die Wahl der Reaktionstemperatur. Es konnte nachgewiesen werden, dass eine gezielte Steuerung der Zusammensetzung des Produktes durch Wahl der Temperatur möglich ist. Das organische Flüssigprodukt besteht zum überwiegenden Teil aus aromatischen Komponenten. Bei Reaktionstemperaturen unter 400 °C erhält man größere Anteile an Methoxy- sowie Hydroxy-substituierte Aromaten, während für Temperaturen über 400 °C der Anteil der sauerstoffhaltigen funktionellen Gruppen sukzessive abnimmt, bis bei 500 °C fast ausschließlich Benzen und dessen Alkylderivate vorliegen. Als wirksame Katalysatoren konnten Eisen- und Molybdänkomponenten identifiziert werden. Besonders Eisen-Schwefelmineralien wie Pyrrhotit sind dabei aufgrund der leichten und günstigen Verfügbarkeit für den Einsatz in einem großtechnischen Prozess geeignet. Da die eigentliche Spaltung der Ligninstruktur vorwiegend thermisch stattfindet, beläuft sich die Wirkung des Katalysators vor allem auf den Transfer von Wasserstoff aus der Gasphase und dessen Bereitstellung in aktivierter Form zur Absättigung der radikalischen, thermochemischen Fraktionierungsprodukte und verhindert so eine Polymerisierung zu koksartigen Feststoffprodukten. Bei der Umsetzung ausgewählter, biogener Reststoffe konnten Flüssigproduktausbeuten von bis zu 65 m.% erreicht werden. Bedingt durch die enthaltenen Polysaccharide entstehen bei der Hydrogenolyse von Biomassen mehr aliphatische Produkte, sowie Kohlenstoffoxide. Basierend auf den experimentellen Ergebnissen konnte eine theoretische Maßstabsvergrößerung durchgeführt werden. Die Auslegung der Anlage erfolgte für eine gemeinsame Verarbeitung von Lignin und erdölstämmigem Vakuumdestillationsrückstand mit einer Kapazität von 500 kt/a. Daraus ergibt sich ein Durchsatz von 65,5 t/h. Das empfohlene Anlagenbudget wurde mit 360 Mio. EUR berechnet. Dabei entfallen die Hauptkosten auf das Reaktionssystem, gefolgt von der Vakuum-Flash-Kolonne und dem Kreislaufgassystem. Die ökologische Bewertung des Verfahrens ergab eine starke Abhängigkeit des Treibhauspotentials und des kumulierten nicht-regenerativen Energieaufwandes von der Art der Wasserstoffquelle. Besonders die Biomassevergasung, als auch die Wasserelektrolyse mit regenerativ gewonnenem Überschussstrom zeigen in Zukunft das Potential die Ökobilanz des Prozesses deutlich zu verbessern, ohne gleichzeitig die Kosten erheblich zu steigern.

The investigation into how life evolved and cellular complexity developed is an ongoing and highly researched pursuit in science. The central goal of my thesis was to develop a bio-inspired synthetic cell model in order to address this important topic. Towards this end, polymer-stabilized water-in-oil droplets were used as cell-sized compartments for the assembly and testing of specific sets of bioactive components. Moreover, an automated, droplet-based microfluidic technology was implemented for high throughput production of these cell-like compartments and their subsequent manipulation. To resemble the eukaryotic cell architecture, I established a highly-tunable method for the on-demand creation of synthetic cell systems in the form of 3D-supported lipid bilayers, multicompartment systems or free-standing giant unilamellar vesicles (GUVs). To accomplish this, small unilamellar vesicles were encapsulated into polymer-stabilized water-in-oil droplets. By tuning the charge of the inner droplet interface, adsorption of lipids can either be inhibited, leading to multicompartment systems, or induced, leading to the formation of droplet-stabilized giant unilamellar vesicles (dsGUVs) or a combination of multicompartment systems and dsGUVs. Following assembly, the successful release of free-standing GUVs from the polymer shell and the oil phase into physiological conditions was demonstrated. This paves the way towards future applications in which synthetic cell interactions with a physiological environment are crucial. Another significant achievement in this thesis was the assembly of a cellular motility module by the reconstitution of actin cytoskeletal networks and adhesion membrane receptors within droplet-based synthetic cells. These disparate cytoskeletal and adhesive elements were united in the lipid membrane structure of dsGUVs. I showed that this module was able to recapitulate key mechanisms in cell migration – namely cytoskeletal pushing and contractile forces. To date, such synthetic cells containing both cytoskeletal and adhesion-associated functional modules capable of self-propulsion has never been demonstrated. Remarkably, this minimal but functional set of building blocks allowed for the generation of autonomous motion in synthetic cells, and led to the analysis of the mechanism behind this self-propulsion. The powerful microfluidic technology and synthetic cell-like compartments presented in this thesis have the potential for widespread and diverse employment in synthetic biology as they allow for the use of varied sets of both synthetic and natural building blocks. I believe that the scientific achievements presented in this thesis will be of great interest to researchers in fundamental biology, bioengineering and biochemistry.

Microfluidics combines principles of science and technology, and enables the user to handle, process and manipulate fluids of very small volumes. This technology permits the integration of multiple laboratory applications into one single microfabricated chip, requires minimal manual user intervention and sample consumption, and allows enhanced data analysis speed and precision. Due to these numerous advantages, the potential for this technology to be applied in fundamental biophysical and biomedical research is vast. The major aim of this thesis was to explore the capacities of microfluidics, particularly droplet-based microfluidic technology in the following topics: 1) Mimicry of the immune system cellular environment, with the ultimate goal of programing T cells for adoptive T cell therapy; 2) Bottom-up assembly of minimal synthetic cells. Towards this end, a novel approach to form gold-nanostructured and specifically biofunctionalized water-in-oil droplets was developed. This thesis highlights the advanced properties of nanostructured droplets to serve as 3D antigen presenting cell (APC) surrogates for T-cell stimulation. The combination of flexible biofunctionalization and pliable physical droplet properties work in tandem, providing a flexible and modular system that closely models in situ APC-T cell interactions. The research within this thesis focused also on the dissection of complex cellular sensory machinery implementing an automated droplet-based microfluidic approach. Towards this goal, nanostructured droplets as cell-sized compartments and droplet-based pico-injection technology were used to achieve the bottom-up assembly of the minimal number of proteins required for a “simple synthetic cell.” While the applied methodology has a potential for assembly of a wide range of subcellular functional units, the focus in this thesis was on the reconstitution of the actomyosin cortex. Successful optimization of the biochemical and biophysical conditions within the droplets allowed to achieve precise control over the actin polymerization and actomyosin network organization by their linkage to the droplets periphery. These experimental steps were also necessary to generate signaling events including myosin-driven droplet migration and self-propulsion with reduced molecular complexity compared to living cells.

Die vielversprechenden Ergebnisse von Alphastrahlern in der gezielten Alphatherapie (TAT) zur Behandlung von Krebs bereiten ein enormes Interesse für Fortschritte in der Forschung der Radionuklid-Produktion und in der Herstellung und Untersuchung von Radioimmunokonjugaten. Zum einen soll der hohe Bedarf therapiegeeigneter Radionuklide gedeckt sein, zum anderen ist es unabdingbar die Eigenschaften der Radioimmunokonjugate zu kennen, um ihr Verhalten in vivo einschätzen zu können. Ziel der vorgelegten Doktorarbeit war die Untersuchung von 2,9-Dicarboxy-1,10- phenanthrolin (DCP) bzw. seiner Derivate 4,7-Bisphenyl-2,9-dicarboxy-1,10-phenanthrolin (DPDCP) und 4,7-Bis(chlorosulfophenyl)-2,9-dicarboxy-1,10-phenanthrolin (BCPDA) hinsichtlich ihrer Komplexierungseigenschaften mit dem Uranyl-Kation.U-230 ist aufgrund seiner optimalen Zerfallseigenschaften im Blickpunkt des Interesses. Mit einer Halbwertszeit von 20.2 Tagen zerfällt es in einer Kaskade und generiert dabei fünf Alpha-Teilchen, die mit einer kumulativen Energie von 34.2 MeV eine hohe zytotoxische Wirkung verursachen können. Der Komplex UO2-DCP bzw. UO2-BCPDA sollte bezüglich seiner Eignung für den Einsatz in der TAT untersucht werden. Blickpunkt waren zunächst die thermodynamischen Eigenschaften des Komplexes, sowie seine analytische Charakterisierung und anschließend die Entwicklung eines effizienten und reproduzierbaren Protokolls für die Kopplung des monoklonalen Antikörpers MabThera® mit dem Liganden DCP, bzw. seiner Derivate BCPDA und 5-Isothiocyanato-2,9-dicarboxy-1,10-phenanthrolin (DCP-NCS) mit anschließender Evaluierung der Uran markierten Konjugate in vitro. Dabei wurde vor allem die zeitabhängige Stabilität unter dem Einfluss verschiedener potenzieller konkurrierender Liganden und im Blutserum untersucht. Außerdem wurde die Bindungsaffinität des schon etablierteren Komplexsystems Ac-225-DOTA-MabThera® an Zellen untersucht. Zunächst wurden die Protonierungskonstanten des Liganden BCPDA mittels der pH-abhängigen Änderung der Absorption mit der UV-Spektroskopie bestimmt. Die ermittelten pKs-Werte von 4.71 und 2.68 in 0.1 M NaClO4 stimmen mit den literaturbekannten Werten des unsubstituierten Liganden DCP überein, welche von Dean et al. untersucht worden waren. Dieses Ergebnis zeigt, dass die Derivatisierung des DCP mit Chlorosulfophenylgruppen keinen Einfluss auf die komplexierenden Eigenschaften der Carboxylgruppen ausübt. Um eine quantitative Aussage über die Stabilität des Liganden mit dem Uranyl-Kation machen zu können, ist die Kenntnis der Stabilitätskonstante eine wichtige Voraussetzung. Diese wurde durch Verwendung der beiden Urantracer U-230 und U-237 und den unterschiedlichen analytischen Methoden Instant Thin Layer Chromatography (ITLC) und dem Kationenaustauscherharz AG MP-50 auf log K 7.4 ± 0.2 in 0.1 M NaClO4 bestimmt. Eine Ionenstärkekorrektur mit der Davies-Gleichung ergab log K 8.2 ± 0.2 bei der Ionenstärke 0. Um die thermodynamischen und kinetischen Eigenschaften des Komplexes beurteilen zu können, wurde der Komplex unter dem Einfluss verschiedener potenzieller konkurrierender Liganden untersucht. Hierfür wurde die Bildung der ternären Komplexe UO2-BCPDA-OH− und UO2-BCPDA-CO2−3 in Abhängigkeit vom pH Wert mit UV-Spektroskopie untersucht. Für die Bildung des ternären Komplexes UO2-BCPDA-OH− konnte in Abhängigkeit vom pH-Wert eine Änderung der Absorption beobachtet werden. Durch Auswertung mit Hilfe einer Steigungsanalyse wurde mit steigendem pH-Wert die Anlagerung einer Hydroxogruppe an den binären UO2-BCPDA Komplex beobachtet. Es konnte unter Vorbehalt eine Bruttokomplexbildungskonstante von log K = 13.2 ± 0.2 in 0.1 M NaClO4 geschätzt werden. Die Bildung des ternären Carbonatokomplexes wurde mit einem erhöhten Partialdruck von CO2 und der damit verbundenen Gleichgewichtskonzentration in Lösung in Abhängigkeit vom pH-Wert untersucht. Hier kam es zunächst zur Bildung des ternären Komplexes. Bei höheren pH-Werten wurde die Dissoziation des UO2-BCPDA Komplexes zugunsten der Bildung des UO2(CO3)34−-Komplexes beobachtet. Zum besseren Verständnis der Komplexierungseigenschaften von UO2-DCP und UO2-DPDCP wurden unterschiedliche Addukte synthetisiert und mit Kristallstrukturanalyse, NMR, IR- und UV-Spektroskopie charakterisiert. Zunächst ist es gelungen das Polymer [UO2-DCP]n mit Hilfe einer einfachen Extraktion zu synthetisieren. Auf analoge Weise wurde mit dem Liganden DPDCP das Tetramer [UO2-DPDCP]4 hergestellt. Die Herstellung und Charakterisierung dieser und weiterer ternärer Kristalle gab ein tieferes Verständnis für das Verhalten des Komplexes unter dem Einfluss verschiedener Liganden, auch in Lösung, und dessen bemerkenswerte kinetische Stabilität. Die Komplexe UO2-DCP, UO2-DPDCP, UO2-BCPDA und die entsprechenden Konjugate UO2-DCP-MabThera® und UO2-BCPDA-MabThera® wurden in vitro untersucht. UO2-DCP und UO2-DPDCP zeigen im Blutserum keine Dissoziation. Eine suggerierte Dissoziation von UO2-BCPDA, UO2-DCP-MabThera® und UO2-BCPDA-MabThera® kann mit Schwierigkeiten der analytischen Methode und der dichten Matrix des Blutserums erklärt werden. Das durchgeführte Zellbindungsexperiment von Ac-225-DOTA-MabThera® an den Lymphomzellen K422 zeigte eine Bindungsaffinität im nanomolaren Bereich an die Zellen. Dieses Radioimmunokonjugat mit dem Antikörper MabThera®, welcher auch für das neue System UO2-DCP untersucht wird, hat somit eine starke Affinität zu den Zellen. Die Untersuchungen und durchgeführten Experimente zeigen, dass das untersuchte System UO2-DCP durchaus Potenzial für den Einsatz in der TAT besitzt, da der Komplex sich durch eine bemerkenswerte kinetische Stabilität auszeichnet. Es sollten jedoch noch weitere Experimente durchgeführt werden, um die Stabilität der Radioimmunokonjugate im Blutserum zu untermauern. Letztendlich muss auch die Immunoreaktivität der hergestellten Radioimmunokonjugate, die Affinität an Zellen, sowie die Zytotoxizität von U-230-DCP-MabThera® bzw. U-230-BCPDA-MabThera® untersucht werden.

Among the different biofouling species, barnacles resemble a specific threat as they are difficult to remove, able to damage fouling release coatings and increase the drag force of ships. Additionally, barnacles are a good model system for research on permanent underwater adhesion strategies. This study aims to understand and compare the spatial organization and the chemistry of the adhesive secreted by two different species (Balanus amphitrite and Balanus improvisus) of cyprid larvae and juvenile barnacles for settlement. Raman spectromicroscopy and synchrotron based X-ray microprobe fluorescence analysis have been applied for the in-situ and ex-situ investigation of juvenile barnacle cement chemistry. Confocal Raman spectromicroscopy revealed the chemical heterogeneity of the barnacle baseplate and allowed to distinguish three regions of various chemical compositions. The adhesive of cyprids was different from the one of larvae and analyzed in detail from the metamorphosis to the age of fourteen days. The results of these studies provided information on the chemical composition and morphological structure of both barnacle species at different life stages.

The synthesis of commercially relevant organic carbonates from CO2 can contribute to a sustainable utilization of this greenhouse gas. The catalytically controlled reaction with epoxides leads to the production of cyclic carbonates and aliphatic polycarbonates. In this work, we succeeded in finding innovative homogeneous catalysts for this task. The foundation was a very variable ligand system closely related to the salen compounds with an N2O2 framework, that was converted with the metals iron, zinc and aluminum to the corresponding metal complexes. The various combinations of ligand and metal yielded 66 different potential catalysts, of which some structures were investigated via x-ray structure analysis. High-pressure experiments were carried out to test the catalysts’ performance, allowing some insights in the relationship between structure and catalytic activity. The conversions were documented by means of the test substrates propylene oxide and cyclohexene oxide. Additionally a wider range of epoxides has been tested in some promising cases. One result is, that the control of the product spectrum via selection of the optimal epoxide-catalyst-combination is possible. The most active iron(III) catalyst was able to produce quantitative yields of propylene carbonate from propylene oxide without the addition of a cocatalyst. With the zinc catalysts the same result was possible, also under mild reaction conditions (40 ◦C, 2 bar CO2, cocatalyst Bu4NI). However, the aluminum catalysts were suitable for the quantitative conversion of cyclohexene oxide to fully alternating polycarbonates. Another important finding is, that the contributing nucleophiles in the reaction have a decisive influence on the formation of the product, regardless if they came from the catalyst itself or from a cocatalyst. While the more nucleophile and according to the HSAB-concept softer iodide anion ismore suitable for the synthesis of cyclic carbonates, the anions bromide and chloride are rather successful in the synthesis of polycarbonates. By the analysis of the many catalytic test results and additional kinetic measurements via in situ FT-IR spectroscopy, it was possible to postulate mechanisms for the different new catalysts of this work.

The successful application of alpha-emitters in targeted alpha therapy (TAT) goes together with developments in radionuclide production and labelling chemistry. Especially profound understanding of the coordination chemistry of the respective metal ion-ligand system is of major importance to develop protocols for the synthesis of radioimmunoconjugates and to predict the fate of radionuclides in vivo. Radioconjugates of the therapeutic alpha-emitter Ac-225 with polyamino-polycarboxyl ligands as chelating agents are being actively studied [1, 2, 3, 4]. In particular the macrocyclic ligand 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) has shown promise due to the high kinetic- and thermodynamic stability (log K > 20) of its complexes with trivalent metal cations [5]. The scope of the presented work was the experimental characterisation and evaluation of DOTA as a suitable chelator for trivalent actinides (An(III)), particularly in terms of stable binding of the long-lived alpha-emitting radionuclide Ac-225 to biomolecules for safe application in radioimmunotherapy (RIT). The project included not only basic studies to contribute to a better understanding of the complexation mechanisms and kinetics, but, based on these findings, was aimed at the development of a robust labelling protocol for facile and effective synthesis of an Ac-225-DOTA-MabThera® conjugate. In the course of the investigations, focus was set on in vitro testing of the obtained radioimmunoconjugate, in particular the evaluation of the kinetic stability in presence of competing agents as well as in human blood serum. Assessment of the antigen binding affinity of the antibody conjugate completed the work. The protocol for the design and synthesis of Ac-225 radiopharmaceuticals of McDevitt et al. provided the starting point for this study [6]. This research group developed a synthetic scheme to radiolabel DOTA-proteins with Ac-225. Later, the protocol was applied to antibodies in form of a two-step synthesis, with the first step being the Ac-225 DOTA-Bn-NCS complexation, followed by the coupling of the Ac-225-DOTA-Bn-NCS to the mAb. The idea behind this two-step approach was that, when the complexation of Ac(III) with DOTA is conducted at elevated temperatures and basic pH (first step), presumably a more stable complex is formed. However, since higher temperature / pH are known to have a negative effect on the antibody efficiency, the conjugation to the biomolecule can hence only be conducted at lower temperatures in a second step. This two-step synthesis though suffers from yields below 10 %, which is assumed to be due to the competing hydrolysis reaction of the isothiocyanate moiety occurring at the pH used during the complexation step. This makes the labelling protocol an interesting subject for further studies on how this synthesis can be improved. From the findings of McDevitt et al it was apparent that a number of variables needed to be investigated in order to improve on the low efficiency of the protocol. These studies were conducted previously and are summarised in the Diploma Thesis, S. Kannengieÿer, 2009 [7]. A one-step synthesis protocol was tested and the labelling yields for Ac-225 were found to be dependent on temperature and especially on the pH of the reaction mixture. Eventually, an optimised protocol for radiolabelling of DOTA-peptides and MabThera® with Ac-225 activities up to 2 µCi (= 74 kBq) per 100 µg mAb was established, offering labelling yields > 95 %. The present work now aimed on translation of the developed synthesis protocol to higher specific activities of clinical relevance (>10 µCi (>370 kBq) per 100 µg mAb). To gain profound knowledge about the complexation reaction mechanism and the thermodynamic and kinetic properties of the An(III)-DOTA system, the coordination chemistry was initially studied by means of time resolved laser fluorescence spectroscopy (TRLFS). Since Ac(III) has no suitable spectroscopic properties, the metal ion complexation by DOTA was investigated with Cm(III) as substitute for the trivalent actinides. A comparable study on [Eu(III)DOTA]- has been reported before [8, 9, 10]. Besides determination of the kinetic rate constants and thermodynamic parameters (log K, deltaG, deltaH, deltaS) at labelling-relevant temperatures up to 90 °C, attention was also paid to the detection of possible intermediate species which are frequently discussed in the literature [11]. TRLFS is a powerful speciation method which makes use of the excellent fluorescence properties of Eu(III) and Cm(III), both regarded as good representatives for trivalent lanthanides and actinides. With TRLFS it is possible to detect and characterise complex species in sub-micromolar concentrations without influencing the chemical equilibrium of the system. An experimental setup was chosen which allows for adjusting the concentration of the reactive DOTA species by variation of the pH of the reaction. Due to the slow kinetics of the complexation reaction at room temperature, experiments at 45 to 90 °C were conducted to identify the complex species and quantify their relative ratios by means of peak deconvolution. Based on the potentiometrically determined pKa,n values of HxDOTA(4-x)- for the respective conditions, from these ratios the conditional complex stability constants log K of [Cm(III)DOTA]- were calculated (I = 0.1, 45 to 90 °C). Application of the van't Hoff law allowed for extrapolation of the log K at 25 °C to be 22.0±0.4. The parameters deltaG, deltaH and deltaS obtained from the Gibbs Helmholtz relation indicate that the reaction is exergonic, endothermic and driven by the change of entropy. Identification and further characterisation of the involved complex species was done by comparison of the fluorescence lifetimes, which give information about the first coordination sphere of the metal cation. Furthermore, additional investigations with NMR were executed to identify and understand the mechanism related to the complex formation with DOTA-Bn-NCS. Based on the results of the NMR study, the complexation kinetics of DOTA and DOTA-Bn-NCS were further investigated and compared to gain insight into the involved reaction mechanisms. Proper understanding and interpretation of the thermodynamic behaviour of the Cm(III)-DOTA complex formation allowed for facile translation of the experimental settings to the Ac(III)-DOTA system. Since no spectroscopic methods are available for this system, Chelex cation exchange resin as well as Instant Thin Layer Chromatography (ITLC) were chosen as radiochemical speciation methods and were evaluated for their feasability. Determination and refinement of the stability constant log K of Ac(III)DOTA]- for the temperature range of 25 to 90 °C was done in analogy to the Cm(III)-DOTA system, resulting in a log K25°C = 19.5±0.4. To obtain reliable results, the protocol for the radiochemical separation of Ac-225 from Ra-225 required optimisation to ensure highest purity and quality of the radionuclide. Based on these findings, the studies on the Ac-225-labelling of DOTA-Bn-NCSMabThera® for targeted alpha therapy of Non-Hodgkins-Lymphoma were subsequently continued. The previously established protocol was modified and further optimised in order to be applicable for facile clinical synthesis of radioimmunoconjugates with higher specific activities (SA) within 20 min. In this regard, the antibody labelling kinetics were reviewed respective reaction temperature and ideal pH of the high-yield radiolabelling, which permitted further improvement of the labelling effectiveness (pH 9, 37 - 42 °C, 5 - 15 min; ave. yields 94 - 96 %, > 98 % RCP after purification). The protocol was successfully evaluated for reliability with SA up to 50 µCi (= 1.85 MBq) per 100 µg mAb. The obtained radioconjugates were assessed for their kinetic stability in different buffers as well as under physiolocigal conditions in human blood serum and proved to be satisfyingly stable over up to 30 days ( > 85 % Ac-225 still bound). Finally, a preliminary radiobiological study with cancer cells (K422 cell line, B-cell lymphoma) was conducted to determine the antigen binding afinity of the radiolabelled CD20-antibody (SA = 1 µCi (= 37 kBq)/100 µg mAb, Bmax= 8.88 nM, Kd = 52.55 nM). The results give rise to further preclinical in vitro studies. In summary, it was demonstrated that rapid, high-yield radiolabelling of DOTAchelated mAbs is possible under alkaline conditions at rather low temperatures. Under these conditions a thermodynamically and kinetically stable radioimmunoconjugates with specific activities suitable for application in clinical TAT studies is formed while the integrity of the antibody is preserved.