Theses and Dissertations from UMD

Permanent URI for this communityhttp://hdl.handle.net/1903/2

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM

More information is available at Theses and Dissertations at University of Maryland Libraries.

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2014 - 20172

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    Bio-Derived Microscale Containers for Disease Treatment and Diagnostics
    (2017) Liu, James; Raghavan, Srinivasa R; Chemical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Micro-erythrosomes (mERs) are microscale containers (3 to 5 µm in diameter) derived from red blood cells (RBCs, also called erythrocytes). They are prepared by removing hemoglobin from RBCs and resuspending the empty structures in buffer. In this work, we focus on adding new functionalities to mERs, with both therapeutics and diagnostics in mind. In our main study, we demonstrate the use of mERs as “Killer Cells” to attack cancer. mERs are loaded with the enzyme glucose oxidase (GOx) and then incubated in vitro with a strain of head and neck cancer cells (15B). In the presence of glucose from external media, the Killer Cells generate hydrogen peroxide (H2O2). H2O2 is a reactive oxygen species (ROS) which induces the cancer cells to undergo apoptosis (programmed cell death). We find a reduction in 15B cell viability of over 80%. In ancillary studies, we explore strategies for the long-term retention of solutes in mERS. Specifically, the cationic biopolymer chitosan is adsorbed to the surfaces of mERs, and the anionic biopolymer alginate is encapsulated in their cores. Both strategies are able to extend the diffusion time for loaded solutes. Additionally, we have attempted to adapt mERs for use as MRI contrast agents by incorporating lipids containing gadolinium into the membrane. These studies lay the foundation for many mER applications and demonstrate their versatility.
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    Finite-Discrete Element Method Simulations of Colliding Red Blood Cells
    (2014) Warner, Benjamin; Solares, Santiago D; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The implantation of artificial heart valves can lead to a large decline in red blood cell life. There has been much research in the last few years dedicated to understanding the cause of this decline. One theory states that collisions at large velocity can lead to spontaneous hemolysis which leads to the premature recycling of cells by the body. Currently, there is no suitable method for modeling the complex intersection interaction of blood cells in a computer code. The Finite-Discrete Element Method (FDEM) is a relatively new computer modeling technique that seeks to combine modeling of continuum-based deformability and discontinuum based motion and element interaction. This thesis utilizes FDEM to model the collision of erythrocytes with other erythrocytes. A method of approximating volume of arbitrary discrete element meshes is proposed and tested for general colliding bodies for accuracy. Red Blood cell simulations are presented with experimentally verifiable data to allow for validation of the model. Future steps are presented for further development of themodel for more specialized applications, such as sedimentation and resting contact. The volume-based FDEM method appears to recreate reasonable results for colliding deformable bodies.