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Doctor of Philosophy (PhD)
Dr. Christine Ann Trinkle
3D cell culture and microfluidics both represent powerful tools for replicating critical components of the cell microenvironment; however, challenges involved in integration of the two and compatibility with standard tissue culture protocols still represent a steep barrier to widespread adoption. Here we demonstrate the use of engineered surface roughness in the form of microfluidic channels to integrate 3D cell-laden hydrogels and microfluidic fluid delivery. When a liquid hydrogel precursor solution is pipetted onto a surface containing open microfluidic channels, the solid/liquid/air interface becomes pinned at sharp edges such that the hydrogel forms the “fourth wall” of the channels upon solidification. We designed Cassie-Baxter microfluidic surfaces that leverage this phenomenon, making it possible to have barrier-free diffusion between the channels and hydrogel; in addition, sealing is robust enough to prevent leakage between the two components during fluid flow, but the sealing can also be reversed to facilitate recovery of the cell/hydrogel material after culture. This method was used to culture MDA-MB-231 cells in collagen, which remained viable and proliferated while receiving media exclusively through the microfluidic channels over the course of several days.
Further modifications were made to create a multi-functional 3D cell culture platform. Gas impermeable polymer structure and deoxygenated flow were used to lower the oxygen content in the device, and the oxygen content was monitored in real-time using embedded oxygen sensors. This is particularly useful in replication of the tumor microenvironment where hypoxic conditions affect the cellular behavior and morphology. Also, by incorporating two inlets in the microfluidic device, binary concentrations of solutes were introduced into the system which created a lateral concentration gradient across the fluidic path. This allows studying of cell migration and response to various chemoattractant and drug doses. And finally, two high throughput designs to create 4-well and eight-well microfluidic devices were proposed and tested. This enables conducting more replicates of an experiment and even comparative studies on a single chip.
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This project was funded by National Science Foundation under Grant No. CMMI-1125722 (2012-2013) and Grant No. CMMI-1538782 (2015-2017). Research reported in this dissertation was supported by the University of Kentucky Center for Cancer and Metabolism, funded through the NIH/NIGMS COBRE program under Grant Number P20 GM121327 (2017-2018). This material is based upon work supported by the National Science Foundation under Cooperative Agreement No. 1849213 (2018-2021).
Torabi, Soroosh, "USE OF MICROSCALE HYDROPHOBIC SURFACE FEATURES FOR INTEGRATION OF 3D CELL CULTURE INTO MULTI-FUNCTIONAL MICROFLUIDIC DEVICES" (2021). Theses and Dissertations--Mechanical Engineering. 175.