Text

theses

ETD doctoral

The application of lab-on-a-chip or microfluidic technologies to perform protein assays is an emerging field and has the potential to be used for point-of-care devices. High-sensitivity and general-use biosensors play a crucial role in achieving this goal. The quantification of protein provides a crucial perspective of pathology, drug treatment, and understanding of the disease.

Label-free electronic affinity-based immunosensing is an attractive candidate as a platform technology for analyzing biomarkers due to the ease of miniaturization and the minimal use of reagents. Electronic-based sensing approaches, however, have lagged behind their optical counterparts in terms of detection limit, selectivity, and reliability. In addition, the matrix-dependent nature of electronic sensing modalities makes the analysis of biomarkers in high salt concentration samples, such as the serum, difficult due to charge screening.
In this dissertation, I present a novel impedance-based nanowell biosensor and its application in multiple novel solutions for detecting protein biomarkers in purified buffers and serum matrixes using a micro-sized biochip. I discuss sensor fabrication, sample preparation, theoretical considerations, data analysis, and various experiments.

In the first chapter, I introduce the fundamental perspective of protein studies and protein quantification and summarize and review the gold standard and state-of-the-art techniques of protein quantification. Next, I introduce the impedance-based biosensors used in protein detection. In the second chapter, I introduce the theory and modeling of the proposed nanowell sensor, including the systematic analysis, determination of the parameters, results of the simulations, and the derivation of the formula. In the third chapter, I propose the nanowell-based label-free assay for the quantitative assessment of cytokine levels, present the results of a series of experiments, and discuss the validity and novelty of the technique. In the fourth chapter, I present multiplexed protein assay measurements achieved using an embedded microprocessor. The standard titration curves of multiple proteins are also presented, followed by the correlation analysis between the nanowell sensor and the Luminex technique and the results of the nanowell sensor to the characteristic biological parameters. In the fifth chapter, I present the most recent results on the analysis of mouse clinical samples with inflammatory arthritis. The results of different experiments with different treatments, a comparison between the standard titration curves of different techniques, and the correlation curves of all samples are presented in this chapter. And in the sixth chapter, the results of human clinical samples including the titration curve of different biomarkers, cytokine levels of different patient samples were introduced.

ETD_11149

Ph.D.

Includes bibliographical references

doi:10.7282/t3-a85d-bg81

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