Utilization of the Phosphorescence of Inorganic and Organometallic Transition Metal Polypyridine Complexes in the Design of New Molecular Probes and Bioimaging Reagents for Nitric Oxide

The aim of this project is the design of novel phosphorescent inorganic and organometallic transition metal polypyridine complexes for use as a new generation of molecular probes and bioimaging reagents for nitric oxide. Nitric oxide is a free radical that serves as a messenger molecule in the cardiovascular, neurotransmission, and immune systems. Since it plays a key role in various important physiological and pathological processes, accurate and sensitive detection of nitric oxide is required. Among the many methods available, fluorescent nitric oxide probes have been attracting tremendous interest due to the rapid development of and advances in confocal laser microscopy, which allows real-time bioimaging with high spatial and temporal resolution. Whilst a number of fluorescent probes have been developed, applications of phosphorescent transition metal complexes in nitric oxide sensing and bioimaging are just emerging and consequently this area is still unexplored. We believe that phosphorescent inorganic and organometallic transition metal complexes are attractive choices as nitric oxide probes owing to their highly environment-sensitive emission properties, high photostability that minimizes photobleaching, and long emission lifetimes that enable the probes to be studied by fluorescence lifetime imaging microscopy with enhanced sensitivity.In this project, we will design new nitric oxide probes and bioimaging reagents derived from phosphorescent inorganic and organometallic transition metal complexes. Various probes will be developed and their reactivity toward nitric oxide will be investigated. Additionally, the cellular uptake, cytotoxicity, intracellular nitric oxide sensing, and bioimaging properties of the probes will also be examined. The favorable photophysical properties of phosphorescent inorganic and organometallic transition metal complexes, together with the strategic design of nitric oxide-specific ligands, will render the proposed probes a novel generation of biological tools that can be utilized in a range of sensing and bioimaging applications.