Metal oxide electrokinetc micropumps & capillary electrophoresis of biomolecules and carbon based nanomaterials
Lassala, Ivonne M. Ferrer
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Separation science is at the center of the analytical laboratory. New technological advances and applications evolve from knowledge obtained in different research areas, such as materials sciences, chemical synthesis, and fluidics, among others. The work in this dissertation relates to two areas: (1) the development of capillary electrophoretic methodology to separate biomolecules and/or nanomaterials, and (2) the synthesis of materials suitable for electrokinetic pumping. By means of capillary electrophoresis (CE), carbon-based nanoparticles were separated based on their charge-to-size ratio, providing unprecedented separations of C-dots, revealing the complexity of these materials when synthesized. Insight into the heterogeneity of these materials as a function of synthetic parameters was studied by means of CE. It is shown that CE coupled with laser-induced photoluminescence (LIP) is an excellent analytical technique to evaluate synthetic routes to produce carbon-based nanoparticles as well as to explore their inherent characteristics. Capillary isoelectric focusing (cIEF), a variant of CE, was used to develop methodology that allows the study of the mammalian target of rapamycin (mTOR) complexes, a serine threonine protein kinase that regulates cell growth, cell proliferation, cell survival and protein synthesis. The high efficiency cIEF separation method has shown the potential for the differentiation of protein complexes similar in size and biochemical composition. A fluorescently labeled antibody was used to monitor the mTOR complexes from cell extracts via cIEF after affinity interaction between the antibody and the complexes. Because of the increased interest in developing devices capable of controlling and manipulating fluid flows within the length scale of millimeters or less, we investigated the electrokinetic pumping capabilities of the metal oxides zirconia and hafnia for the fabrication of electrokinetic micropumps (EKP). These are a type of dynamic pumping systems based on electroosmotic flow (EOF). Zirconia and hafnia monolithic materials were synthesized and their physico-chemical and electrokinetic properties were first evaluated. Evaluation of zirconia and hafnia EKPs showed that these metal oxides were superior to the typical EKPs fabricated from silica based monolithic structures. Zirconia in particular can generate electroosmotic flows to pump neat methanol at much higher flow rates than the traditional silica-based EKPs. These findings will have impact the areas of chromatography, microfluidics, and in methanol-based fuel cells.