Infoscience

Thesis

Stencil Lithography and Inkjet Printing as New Tools for Life Sciences Research

This thesis work focuses on applying microtechnology to produce three toolkits for life-sciences research. The first technique presented is nanostencil lithography for patterning cell adhesions. Nanostencil lithography is a shadow-mask micro and nanopatterning technique that was adapted for patterning on silicone rubber (PDMS) in the course of this work. Once a specific material contrast is present on the substrate, the patterns can be 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'. Micro and nanopatters were successfully created on both PDMS, glass, and even polytetra fluoroethylene. The second part of this work 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 manner analogous to an industrial rapid prototyping system. One of the main hurdles at this point remains the fact that printed hydrogels tend to show complete spreading on other printed hydrogels (or, like spreads on like). This work details how the materials properties of a hydrogel system can be optimized to get 3D hydrogel printing analogous to a rapid prototyping system. It goes on to show how an optimized printing process can permit the printing of branched vasculature – a key requirement in tissue engineering applications. The final part of this work focused on creating an X-ray microcollimator to study subcellular (and sub-nuclear) 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 IR damage to single stripe lengths. This work was initially funded by the SNF project: 205321-112323, and later by a SystemsX demonstration fund.

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