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.
Browse
2 results
Search Results
Item CONCENTRATION ENHANCEMENT AND DEVICE FABRICATION FOR THE IMPROVED PERFORMANCE OF GRADIENT ELUTION MOVING BOUNDARY ELECTROPHORESIS(2014) Sikorsky, Alison Anne; Fourkas, John t; Chemistry; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Many recent efforts in the field of microfluidics have been focused on reducing the size and the complexity of devices and on simplifying the methods of analysis performed with them. Gradient elution moving boundary electrophoresis (GEMBE) is a recently described counterflow electrophoresis method that was developed to simplify the analysis of ions in complex matrices. In this thesis, the improvement of the limit of detection of GEMBE and reduction of the GEMBE channel length is investigated. Integration of simple and robust device components required for the successful adaptation of many analytical methods to multiplexed and field-portable devices often has negative effects on detection sensitivity, such as in the optical detection components in a capillary electrophoresis (CE) system. One of the simplest methods to improve sensitivity in the CE field is known as sample stacking. This method involves preparing the sample in a buffer with a different concentration (and conductivity) than that of the run buffer, such that when an electric field is applied the analyte concentration is increased at the boundary between the two different buffer concentrations. A method in which the sample is prepared in a buffer at a lower concentration than the run buffer has been implemented. This method achieves a significantly greater signal enhancement than expected for sample stacking. The concentration enhancement ability of this method is demonstrated utilizing GEMBE with channel current detection. Current GEMBE device construction methods impose limitations on the minimum length of the separation channel. One technique well suited for minimizing the size of the GEMBE separation channel is multiphoton absorption polymerization (MAP). Because MAP is a non-linear optical fabrication method, polymerization is limited to a small region near the focal point of a laser beam. As a result, three-dimensional structures with small feature sizes can be easily created. The 3D capabilities of MAP have been exploited to create channels with circular cross sections and ~300 μm lengths for GEMBE. The integration of device components fabricated with MAP and molded with PMDS allows visualization of the GEMBE separations, and provides insights into the effect of channel length on GEMBE step width.Item Proteomic Analysis of Plasma Membrane Proteins from Drug Susceptible and Drug Resistant Breast Cancer Cell Lines(2004-11-08) Rahbar, Amir Mikel; Fenselau, Catherine C; Biochemistry; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Drug discovery is an important field of research in the biotechnology and pharmaceutical industries. Plasma membranes are rich in drug targets and other proteins responsible for cell signaling, transport, signal transduction, and other cellular functions. Information obtained about these proteins, and the pathways they participate in, helps to facilitate the drug discovery process. Although these plasma membrane proteins play important roles in cellular function, they are usually expressed in very low abundance and are therefore hard to identify and analyze. Comparative proteomic analysis of plasma membranes in different types of cells or different disease states of the same cell or tissue type can help to design targeted therapies specific to particular cell or tissue types and can be used in the identification of biomarkers for early disease detection. In order to be able to identify proteins in the plasma membrane it is important to start out with a plasma membrane fraction that is free of contamination from other more abundant proteins from other portions of the cell. 2D gel electrophoresis is the primary protein separation tool for use with proteomics and drug discovery, however, the inability of membrane proteins to be separated using isoelectric focusing, which is the first step in the 2D gel protocol, excludes 2D gel electrophoresis as a viable technique for the separation of membrane proteins. This thesis develops and evaluates a method to identify proteins found in the plasma membranes of mammalian cells using a modified form of the cationic colloidal silica technique for plasma membrane isolation combined with analysis of these proteins using mass spectrometry. This method is then used in combination with metabolic stable isotope labeling to identify protein expression changes between the mitoxantrone drug susceptible and drug resistant MCF-7 breast cancer cell lines.