Biomedical Engineering ETDs

Publication Date

Summer 7-15-2020

Abstract

Neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease,

and related tauopathies, are a global health care challenge due to the lack of early

treatment and diagnostic options. These diseases take an emotional and physical

toll on patients, caretakers, and a rather large economic toll on taxpayer-based

health care systems. The pathologies of these diseases are characterized by the

aggregation of misfolded proteins, amyloid-β (Aβ) and tau, into β-sheet rich

structures called amyloids. Research has found that the presence of protein

aggregates predates cognitive symptoms by years. Current diagnostic tools are

based on the detection of these amyloid aggregates, historically by using

histological stains to confirm disease diagnosis postmortem. This research

investigated the sensing and potential for therapeutic application of a novel class

of luminescent molecular sensors, oligo-p-phenylene ethynylenes (OPEs) in

vitro, ex vivo, and their permeability through the blood-brain barrier. First, a small

library of OPEs was tested for their amyloid aggregate sensing selectivity and

sensitivity using model proteins hen-egg white lysozyme and bovine insulin to

identify optimal sensors through fluorimetry assays (Chapter 2). The top

candidates were further tested with pathology relevant proteins: tau hexapeptide

306VQIVYK311, Aβ40, Aβ42, and α-synuclein (Chapters 3-4). From here we

moved to evaluate OPEs as histochemical markers of disease by staining

transgenic mice (rTg4510), transgenic rats (TgF344-AD), and human brain

sections from patients diagnosed with frontotemporal dementia (Chapter 5).

Next, we moved to test the OPEs blood-brain barrier permeability. We worked

towards this goal by visualizing the partition using the molecule’s equilibrium in

octanol/water phases and using a 3-D microfluidic “blood-brain barrier on a chip”

Synvivo BBB (Chapter 6). Lastly, OPEs photosensitizing properties were

studied by creating a detergent-OPE model system. Using transient absorption

and singlet oxygen chemical traps, we found that OPEs can generate singlet

oxygen through a controllable, binding induced, fluorescence-dependent,

mechanism. This targeted photosensitizing action gives OPEs potential as

therapeutic agents in photodynamic therapy applications (Chapter 8). This

research is aimed at providing a research tool for identifying patients in the early

stages of disease who would then be eligible and ideal candidates for clinical

trials and has the power to become a critical technology with broad protein

detection for researchers by providing a tool for monitoring treatment effects and

efficacy.

Language

English

Keywords

Alzheimer's Disease, Protein Aggregate Detection, Fluorescent Optical Probes, Oligomeric-p-Phenylene Ethynylene

Document Type

Dissertation

Degree Name

Biomedical Engineering

Level of Degree

Doctoral

Department Name

Biomedical Engineering

First Committee Member (Chair)

Eva Y. Chi, Ph.D.

Second Committee Member

Kiran Bhaskar, Ph.D.

Third Committee Member

David G. Whitten, Ph.D.

Fourth Committee Member

Benjamin Clark, Ph.D.

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