Series in MICROSYSTEMS
edited by P. A. Besse,
R. S. Popovic,
Kristopher A. Pataky
Stencil Lithography and Inkjet Printing as
New Tools for Life Sciences Research
2011. XIV, 172 p.; € 64,00. ISBN 3-86628-395-4
This thesis manuscript describes the application of micro and nanotechnology to produce three toolkits for life-sciences research. The first technique presented is nanostencil lithography for patterning cellular adhesion sites with the ultimate goal of studying mechanosensitive gene expression. Nanostencil lithography is a shadow-mask micro and nanopatterning technique that was adapted for patterning metal on silicone rubber (PDMS) in the course of this work. Once a specific material contrast is present on the substrate, the patterns can be chemically functionalized using highly selective surface modification techniques. In this work, Au micro and nanopatterns were rendered cell-adhesive by grafting a thiolated peptide (presenting an RGD moiety) to their surfaces. The micro and nanopatters were used to study whether geometric confinement could prevent a mammalian cell’s primary ‘focal contacts’ from developing into mature ‘focal adhesions’. Au micro and nanopatters were successfully created on PDMS, glass, and even polytetrafluoroethylene.
The second part of this manuscript focuses on 3D bioprinting. Recently, 3D printing has received attention as a possible means of assembling heterogeneous tissue mimetics and ultimately entire organs. However, to date no one has shown true 3D printing of hydrogels in a ‘block by block’ manner analogous to industrial rapid prototyping systems. One of the main hurdles is the fact that printed hydrogels tend to show complete spreading on other printed hydrogels (or, like spreads on like). This work details how the material properties of a hydrogel system can be optimized to obtain 3D hydrogel printing analogous to a rapid prototyping system. It goes on to show that this optimized printing process enables the fabrication of branched microvasculature - a previously undemonstrated but key requirement in the engineering of bulk tissues and organs.
The final part of this manuscript describes the creation of an X-ray microcollimator to study subcellular and subnucleolar damage responses in cells. While many molecular biologists use ionizing radiation (commonly from X-ray tubes) to induce damage in cells, current X-ray microcollimators only work well with costly synchrotron radiation sources. During the course of this thesis, an X-ray microcollimator was developed that is compatible with conventional X-ray tube setups. The device collimates 20 - 30 keV X-rays into irradiation stripes between 0.5 and 10 µm in diameter. Results with the microcollimator show that it is effective in limiting X-ray damage to single sub-cellular and sub-nucleolar stripe zones.
Keywords: BioMEMS, biomaterials, nanopatterning, surface modification, ionizing radiation, microcollimator, bioprinting, inkjet, hydrogels, tissue engineering, life sciences.
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