Over the last decades cell biology has fundamentally transformed our understanding of biological functions and cell research has become ubiquitous in today´s scientific world. Although studying in vitro cell cultures is an essential aspect of cell biology, its technological advancements has fallen dramatically behind compared to progress made in the fields of genomics, proteomics and high-throughput testing of biochemicals. In turn, the combination ofmicrofluidics with live cell culture systems has facilitated dynamic manipulation of culture conditions to provide a microenvironment that allows formation of complex and physiological relevant artificial tissues from cultured cells. In these diagnostic systems, called assays, cell cultures of different origin are employed and their functional response to drugs and chemicals, are detected. To foster the development of next generation cell-based assays, miniaturisation, automation and integration was advanced in this thesis. The most frequently used material for microfluidic cell-based assays is poly(dimethylsiloxane) (PDMS), which comes with several limitations including high water-vapour permeability, high compliance and it does not promote direct adhesion of cells. Therefore, in this work a novel thermoset material (OSTEMER) compatible with soft lithography and reactive injection moulding was investigated as an alternative material for cell-based assays. Apart from its versatile fabrication possibilities, hydrophilicity, optical clarity, low water vapour permeability and biocompatibility, several multi-layered, membrane-integrated microdevices for barrier and 3D tissue structures have been developed and characterised. Moreover, automated fluid handling components such as a microvalves, micropumps and degassers are presented in this work. An important aspect of cell-based assays is the establishment of well-defined and reproducible test conditions. Therefore, two microdevices with an integrated mechanical actuator have been developed, characterised and applied for microfluidic migration and wound healing assays. The pneumatically-controlled membrane deflection/compression method not only generates highly reproducible injuries but also allows for repeated wounding in microfluidic environments. Additional performance analysis demonstrated that applied surface coating remain intact even after multiple wounding, while cell debris is mainly removed using laminar flow conditions. Furthermore, only a few injured cells were found at the edges along the circular cell-free areas, thus allowing reliable and reproducible cell migration of a wide range of surface sensitive anchorage dependent cell types. To additionally automate the readout of cell-based assays, a non-invasive, label-free biosensing technique was developed based on electrical cell impedance spectroscopy. Here the influence of high-k nanolayer passivationmaterials for highly polarisable electrodes was theoretically and experimentally investigated. Final practical application of the zirconiumdioxide nanolayer passivated impedimetric sensors is demonstrated for nanotoxicological investigations, where sensitivity and repeatability are crucial parameters for cell analysis. Results of the study show that the reproducible deposition of a uniformmetal oxide nanocoating improves current density distributions, has no performance drawbacks compared to open sensors and enables sensitive detection of protein-coating effects on cytotoxic silica nanoparticles as well as stem cell differentiation.
|Betreuer/-in / Berater/-in|
|Datum der Bewilligung||15 Dez. 2015|
|Publikationsstatus||Veröffentlicht - 2015|
- Biosensor Technologies