Date of Award

Winter 2013

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biomedical Engineering

First Advisor

June Feng

Abstract

In this work, microfluidic devices were developed for enriching post-translational modified proteins. Post-translational modifications (PTM) of proteins play essential roles in cellular physiology and disease. The identification of protein substrates and detection of modification site helps understand PTM-mediated regulation in essential biological pathways and functions in various diseases. However, PTM proteins are typically present only at trace levels, making them difficult to identify in mass spectrometry based proteomics. This work study is about the design, fabrication and testing of the microfluidic device for the enrichment of abundant amount of PTMs. Carbonylated protein is used as a representative PTM to illustrate the wide application of this method for any PTMs converted into a tractable tag after derivatization. The surface topography, surface functional group mapping and elemental composition changes after each modification step of the treatment process were systematically measured qualitatively and quantitatively. Quantitative study of capture efficiency and elution efficiency of the device was also studied. Furthermore, there are also ideas that this proteome enrichment device can be assembled with other lab-on-a-chip components for follow-up protein analysis. For example, coupling with mass spectrometry will allow automatic low-volume fraction deposition on mass spectrometry.

As a part of the microfluidic device designing, this work also aims at optimizing the operating parameters and geometric parameters of microfluidic devices with microscale posts. The operating parameters studied are Reynolds number, Peclet number, Damköhler number, and equilibrium reaction constant. These parameters encompass the influence of velocity, diffusivity, density, viscosity, hydraulic diameter, inlet concentration of species and forward and backward reaction constants. This work theoretically analyzes the influence of the above mentioned operating parameters using finite element analysis software COMSOL Multiphysics 4.2.a. The results of this study would improve the design of microfluidic devices used for chemical reactions as well as that used for protein enrichment.

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