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Microfabrication and Silicification: the control of In Vitro and In Vivo Silica deposition and potential applications

Butler, Randall Thomas
http://rave.ohiolink.edu/etdc/view?acc_num=osu1406642409

Abstract Details

2005, Master of Science, Ohio State University, Materials Science and Engineering.
Through the control of proteins and other biomolecules, organisms such as diatoms are able to produce silica in intricate, nanoscale forms under ambient conditions. The ability to produce silica under benign conditions, termed biosilicification, stands in contrast to many current industrial processes for making inorganic materials that require extreme reaction conditions and are energy intensive. Many previous research studies have begun to reveal the mechanisms by which biosilicification occurs, and studies with proteins and other synthetic catalysts have begun to elucidate the chemical and physical influences upon silica formed in vitro. Microfabrication is the design and production of devices with characteristic dimensions on the micron scale. An increasing array of engineering tools has been used to build a variety of microdevices for a range of applications. Foremost among these tools is photolithography, which uses ultraviolet radiation to create two-dimensional patterns. Photolithography does, however, have several inherent limitations, including the types of materials and surface chemistries it can pattern. To address these limitations, the field of soft lithography has emerged. Through the use of elastomeric stamps and molds, soft lithography has enabled the patterning of a wide range of materials on many different surfaces. The work presented in this thesis represents a union of ambient silicification and microfabrication. In an effort to control the spatial and geometrical in vitro deposition of silica, the peptide poly-L-lysine (PLL) was patterned on a variety of substrates. PLL was patterned on silicon through photolithography and on metal, ceramic, and polymer substrates with soft lithography. Subsequent exposure of the PLL-substrate templates to dilute solutions of silicic acid led to the selective deposition of silica in the regions patterned with the peptide. Scanning electron microscopic examination of the reacted samples showed that the silica was consistently patterned with 10-µm resolution with a morphology that varied with the substrate material. Energy dispersive spectroscopy was used to verify that the patterned material was silica. The methods established for pattering silica were utilized to complete the early stages of the fabrication of a gas adsorption sensor. The soft lithographic technique was used to pattern silica lines on polyimide with interdigitated gold electrodes. In order to functionalize the sensor, the silica will be chemically converted to titania, a semi¬conducting ceramic whose conductivity is sensitive to the presence of gas. In addition to the gas sensor fabrication, the silica patterning principles were extended to control the deposition of gold nanoparticles from solution. Taking account of solubility, different methods were employed to pattern poly-L-tyrosine on silicon and the 3X Flag peptide on nickel. The latter template demonstrated the ability to selectively deposit gold nanoparticles. In addition to work to control in vitro silicification, microfabrication techniques were used to create devices to manipulate in vivo silicification. Through a combination of photolithography and soft lithography, membrane filters were patterned with hexagonal arrays or microwells to confine and manipulate the geometry of cells. The ability of the microreservoirs to confine cells was demonstrated with human fibroblasts. The devices are now being used with diatoms to manipulate the geometry of their silica cell walls for potential use in new micro- or nanotechnological applications. The thesis concludes with the discussion of the initial stages of the fabrication of a microfluidic mixing device. Through the inclusion of chemically converted diatoms, the micromixer should induce mixing through alternating surface charge. Results of the fabrication of micromixers with embedded diatoms are presented, and considerations for the future testing and refinement of the device are discussed. The work presented in this thesis combines microfabrication and ambient silicification. Through the utilization of microfabrication techniques, either in vitro or in vivo silicification can be controlled or diatoms can be incorporated into a microdevice. These abilities could find application in the production of new silicon-based materials or new micro- or nanotechnological devices.
Derek Hansford (Advisor)
Nitin Padture (Committee Member)
120 p.
Materials Science

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Citations

  • Butler, R. T. (2005). Microfabrication and Silicification: the control of In Vitro and In Vivo Silica deposition and potential applications [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406642409

    APA Style (7th edition)

  • Butler, Randall. Microfabrication and Silicification: the control of In Vitro and In Vivo Silica deposition and potential applications. 2005. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1406642409.

    MLA Style (8th edition)

  • Butler, Randall. "Microfabrication and Silicification: the control of In Vitro and In Vivo Silica deposition and potential applications." Master's thesis, Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406642409

    Chicago Manual of Style (17th edition)

osu1406642409
215
© 2005, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.