Entwicklung eines maskenlosen Fotolithographiesystems zum Einsatz im Rapid Prototyping in der Mikrofluidik und zur gezielten Oberflächenfunktionalisierung

In dieser Arbeit wurde eine auf einem Mikrospiegelarray basierende, maskenlose Lithographieanlage entwickelt und aufgebaut, mit welcher Einzelbilder nahtlos nebeneinander projiziert werden. Es wurden über Abformprozesse und direktlithographisch aus verschiedenen Polymeren cm² große Mikrofluidikchips mit 50 µm Kanälen in wenigen Stunden hergestellt. Zudem wurden biochemische Ligandenmuster in 256 verschiedenen Dichtegraden in wenigen Sekunden auf 5 mm² Fläche mit wenige µm großen Pixeln erzeugt

Long-Term Stability of Polymer-Coated Surface Transverse Wave Sensors for the Detection of Organic Solvent Vapors

Arrays with polymer-coated acoustic sensors, such as surface acoustic wave (SAW) and surface transverse wave (STW) sensors, have successfully been applied for a variety of gas sensing applications. However, the stability of the sensors’ polymer coatings over a longer period of use has hardly been investigated. We used an array of eight STW resonator sensors coated with different polymers. This sensor array was used at semi-annual intervals for a three-year period to detect organic solvent vapors of three different chemical classes: a halogenated hydrocarbon (chloroform), an aliphatic hydrocarbon (octane), and an aromatic hydrocarbon (xylene). The sensor signals were evaluated with regard to absolute signal shifts and normalized signal shifts leading to signal patterns characteristic of the respective solvent vapors. No significant time-related changes of sensor signals or signal patterns were observed, i.e., the polymer coatings kept their performance during the course of the study. Therefore, the polymer-coated STW sensors proved to be robust devices which can be used for detecting organic solvent vapors both qualitatively and quantitatively for several years

Entwicklung eines maskenlosen Fotolithographiesystems zum Einsatz im Rapid Prototyping in der Mikrofluidik und zur gezielten Oberflächenfunktionalisierung

In this work, a maskless lithography device based on a micro-mirror array was designed and built. Single projection frames are seamlessly projected next to each other. Microfluidic chips of several cm² size comprising channels of 50 µm have been built of various polymers via direct lithography and casting. Also, bio-chemical ligand patterns comprising 256 different ligand densities have been created in a few seconds on a 5 mm² substrate with pixel sizes of a few µm

Capnocytophaga canimorsus. interaction with the innate immune system

We show that Capnocytophaga canimorsus strain 5 (Cc5) is even more resistant to phagocytosis and killing by murine macrophages (J774.1) and human polymorphonuclear neutrophils (PMNs) than Yersinia enterocolitica, which is known as a model bacterium for resistance against phagocytosis due to its type 3 secretion system (Grosdent et al., 2002). We observed that Cc5 even becomes completely resistant to phagocytosis at high multiplicity of infection (moi of 50). In addition, we demonstrate that the Cc5 transposon mutant Y1C12, identified during a serum sensitivity screen, has an increased sensitivity to phagocytosis and killing by either murine macrophages or human PMNs even in the unopsonized state. This indicated that not an increased susceptibility for antibody binding or complement deposition led to an increased phagocytosis of the mutant, but that rather the outer surface was more readily recognized by the phagocytes. Furthermore, we demonstrate that Cc5 induces the formation of neutrophil extracellular traps upon infection of human PMNs in vitro and that Cc5 is trapped and killed within neutrophil extracellular traps, indicating sensitivity of Cc5 towards antimicrobial peptides present in PMN granules. Analysis of serum resistance in Cc5 revealed that serum resistance is probably linked to its lipopolysaccharide, which prevents deposition of the membrane attack complex on the bacterial surface. Moreover, we have observed that upon growth in the presence of cells, Cc5 releases or modifies factor(s) in the medium, which interfere with the killing ability of macrophages. Investigating the underlying mechanism, we could show that Cc5 does not affect phagosome maturation, but blocks the oxidative burst. This capacity was shown to depend on the release of the zinc metallopeptidase pitrilysin by Cc5. First analyses on the prevalence of the hypothetical virulence factors serum resistance and interference with the oxidative burst indicated that C. canimorsus strains might display strain variability. While 59% of the strains (50% of case strains, 61% of dog isolates) were able to block the killing ability of macrophages, 60% of the strains were highly serum resistant (100% of case strains, 54% of dog isolates). However, serum resistance could not be directly linked to a specific polysaccharide structure in C. canimorsus. November 2009, Salome Casutt-Meye