Abstract
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.
Originalsprache | Englisch |
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Gradverleihende Hochschule |
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Betreuer/-in / Berater/-in |
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Datum der Bewilligung | 15 Dez. 2015 |
Publikationsstatus | Veröffentlicht - 2015 |
Research Field
- Biosensor Technologies