Fluorescence detection of platinum, copper, and hydrogen peroxide in live systems

Development of fluorescence detection methods for biologically relevant metal ions and reactive oxygen species are described herein. The adoption of chemical probes as a broadly used analytical technique has been slowed due to synthetic effort required to develop new probes. Furthermore, low sensitivity and selectivity of chemosensors have hindered their widespread use. Two projects are described herein; the first project use a re-engineering approach to chemical probe discovery to develop reactions for platinum and copper. The second project uses a traditional chemical synthesis to develop a probe for hydrogen peroxide. To date, there are no chemosensors that are more reactive for platinum than palladium; current chemosensors for copper are not sufficiently sensitive to detect intracellular copper. The third project developed a novel probe to selectively detect hydrogen peroxide. The most commonly used chemosensor for reactive oxygen species, dichlorodihydrofluorescein diacetate, often is erroneously used for detection of hydrogen peroxide. More recently developed probes have resolved the selectivity issue, but kinetically cannot compete with intracellular proteins. The first chapter describes the development of a platinum-selective and copper-selectve sensing method. A library screening of metals versus ligands is used to identify one ligand that was able to facilitate a reaction more efficiently with platinum than palladium. Optimizations to the method, eventually leading to the application of the chemical probe to visualize differences in cisplatin distribution in cisplatin-sensitive and cisplatin-resistant head and neck cancer cells, are described. A library screening approach also identified several ligands capable of facilitating a copper-mediated depropargylation reaction. The reaction conditions were then optimized to develop a method capable of detecting copper in mock-pharmaceutical samples and intracellular copper distributions. The second chapter describes the development of a chemosensor for hydrogen peroxide. Selectivity studies were performed with several controls to verify that the probe was selective for hydrogen peroxide over other reactive oxygen species. Kinetic studies showed that the probe reacted more rapidly with hydrogen peroxide than any currently available probe. The probe was also used to validate previous findings in a zebrafish wound-healing model using a genetically encoded sensor