Long-wavelength, reaction-based, fluorescent sensors for HNO and mobile zinc

Abstract

Chapter 1. Introduction A variety of inorganic molecules and ions participate in complex biological signaling networks. Three of these species are nitric oxide (NO), nitroxyl (HNO), and mobile zinc. Maintaining the homeostasis of these signaling molecules is vital and a deeper comprehension of their roles could help in understanding the pathology of specific diseases associated with their dysregulation. One method used to monitor levels of these analytes in biological samples is fluorescence microscopy. Shifting the fluorescence emission to longer wavelengths would improve these already existing probes. Having access to red and near-infrared (NIR) sensors is particularly useful for investigating the interplay of multiple analytes using fluorescence microscopy in conjunction with other probes that emit at shorter wavelengths. Chapter 2. Synthesis and Characterization of a Fluorescent Sensor with a Dihydrothioxanthene Fluorophore and a Quinoline Based Cu(II) Binding Site A NIR probe designed to detect NO was synthesized and its photophysical properties were fully characterized. Analysis of the photophysics of this sensor revealed that the quinoline-binding site might be quenching the fluorescence of the fluorophore and preventing a turn-on response upon addition of NO. Chapter 3. Synthesis, Characterization, and Implementation of a Near-Infrared Fluorescent Sensor for Detection of Nitroxyl (HNO) A NIR sensor for the detection of HNO was synthesized, fully characterized, and used in live HeLa cells to detect exogenously applied HNO. This probe is selective for HNO over thiols and many other biologically relevant analytes. This sensor was used in combination with the green, zinc-specific probe ZP1 to investigate the relationship between exogenously applied HNO and the release of mobile zinc in HeLa cells. Chapter 4. Characterization and Targeting of a Red Zinc Sensor To investigate the levels of mobile zinc in specific cellular organelles, attempts were made to target a red zinc-specific probe to acidic vesicles, the mitochondria, and the nucleus. A combination of peptide-based and small molecule-based targeting approaches was explored, including the vesicle-targeting R9 peptide, the mitochondria-targeting triphenylphosphonium ion, and the DNA-binding Hoechst dye.