Degree
Doctor of Philosophy (PhD)
Department
Department of Chemistry
Document Type
Dissertation
Abstract
Fluorescence imaging based on exogenous small-molecule probes may significantly impact diagnosis and treatment of cancer. However, its potential has yet to be attained due to limitations with probe selectivity and depth of image generation. Fidelity of fluorescence signal production to only those areas of tissue containing diseased cells is envisioned through use of molecular probes whose emission is altered or revealed upon a specific reaction between probe and intracellular targets. A major challenge to fulfill the great promise of fluorescence imaging for diagnosis and treatment of cancer is the development of responsive materials that signal the presence of key characteristics linked to diseased tissue and cells. A potentially impactful approach involves the use of intracellularly activated, small-molecule fluorescent probes that track and target a particular disease-linked enzyme with high selectivity and allow for visual inspection of enzyme activity presence with low levels of detection. To address this, fluorescent probes showing the capability to alter their emission energies, and amplification in their signal intensity by enzyme action, while also providing the necessary spectral window, are to be created. Efforts in the McCarley research group target the cancer biomarker hNQO1, human NAD(P)H: quinone oxidoreductase-1 enzyme, because of its overexpression in various patient-derived cancers and its cytoprotective effect on cancer cells, which is postulated to be involved with cancer treatment resistance and cellular escape mechanisms that lead to the spread of the disease. In this work, I have designed and synthesized three near-infrared fluorescent probes: Q3NCyN, Q3NNOMe, and Q3NBz, and demonstrated their ability to report on hNQO1 presence selectively and sensitively in 2-dimensional cell cultures. High selectivity of this overexpressed 2-electron-specific quinone reductase is ensured by the probes having a highly tuned quinone trigger group/motif whose reduction initiates subsequent bond-breaking release of fluorescent reporter, as demonstrated by optical and fluorescence spectroscopy. Confocal laser scanning microscopy and spinning disk microscopy experiments confirm highly selective and sensitive detection of the oxidoreductase in hNQO1-positive cell lines vs those devoid of or having limited hNQO1 expression. These probes show great potential for early tumor detection, relapses, and disease monitoring to reduce cancer mortality rates based on fluorescence imaging of cancer cells with upregulated hNQO1 enzyme.
Date
3-26-2025
Recommended Citation
Jomy, Stephy, "Visualizing Cancer Cells with High Fidelity Using Enzyme-Responsive Fluorescent Probes" (2025). LSU Doctoral Dissertations. 6703.
https://repository.lsu.edu/gradschool_dissertations/6703
Committee Chair
McCarley, Robin L.
Included in
Analytical Chemistry Commons, Medicinal-Pharmaceutical Chemistry Commons, Organic Chemistry Commons