Browsing by Author "Hosseini, Seyed Yahya"

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    3-D Bio-inspired Microenvironments for In Vitro Cell Migration
    Hosseini, Seyed Yahya (Virginia Tech, 2015-10-21)
    Cancer metastasis is the leading cause of death related to cancer diseases. Once the cancer cells depart the primary tumor site and enter the blood circulation, they spread through the body and will likely initiate a new tumor site. Therefore, understanding the cell migration and stopping the spread in the initial stage is the utmost of importance. In this dissertation, we have proposed a 3-D microenvironment that (partially) mimics the structures, complexity and circulation of human organs for cell migration studies. We have developed the tools to fabricate 3-D complex geometries in PDMS from our previously developed single-mask, single-etch technology in silicon. In this work, 3-D patterns are transferred from silicon structures to glass following anodic bonding and high temperature glass re-flow processes. Silicon is etched back thoroughly via wet etching and the glass is used as master device to create 3-D PDMS structures for use in dielectrophoresis cell sorting applications. Furthermore, this work has been modified to fabricate 3-D master devices in PDMS to create 3-D structures in collagen hydrogels to mimic native tissue structures. We have studied the interaction of endothelial cells with model geometries of blood vessels in collagen hydrogel at different concentrations to mimic the biomechanical properties of tissues varying from normal to tumor under the growth factor stimulation. Finally, we have designed and fabricated a silicon-based transmigration well with a 30um-thick membrane and 8um pores. This platform includes a deep microfluidic channel on the back-side sealed with a glass wafer. The migratory behavior of highly metastatic breast cancer cells, MDA-MB-231, is tested under different drug treatment conditions. This versatile platform will enable the application of more complex fluidic circulation profile, enhanced integration with other technologies, and running multiple assays simultaneously.