Phosphorescent Conjugated Polymers Based On Non-covalent Bond Interaction:Design,Synthesis And Biological Applications

Oxygen(O2) is very important for human life. It is generally believed that hypoxia is a distinct feature of solid tumors. Detection of O2 levels in cells has become a hotspot in the field of biomedical research. As a kind of important oxygen sensor, phosphorescent probes based on transition-metal complexes are widely used for fully reversible, noninvasive and real-time monitoring of intracellular oxygen. Among these phosphorescent complexes, iridium(III) complexes have been widely used in biological hypoxia detection due to the advantages including intense phosphorescence at room temperature, significantly longer emission lifetime compared to purely organic luminophore, and tunable emission colors in the entire visible region. Compared with fluorescent molecules, conjugated polymers(CPs) exhibit many advantages: such as higher extinction coefficient, better photostability and longer Stokes shift. In addition, CPs offer a lot of binding sites to interact with analytes. Owing to the unique optical properties, CPs have recently attracted increasing attention in the biomedical field. In this thesis, a class of anionic iridium complexes have been designed, synthesized and applied in the biosensing field. Furthermore, the anionic iridium complexes were adopted to construct the non-convalent fluorescence/ phosphorescence dual-emissive solf salt with CPs for hypoxia imaging through ratiometric and lifetime imaigng. Topics include the following two aspects:1. A class of anionic transition metal iridium complexes were designed and synthesized. Compared to the neutral and cationic iridium complexes, these anionic iridium complexes exhibited special advantages, including simpler synthetic rout, higher production rate, lower biological toxicity and better biocompatibility. The complexes were further applied to sensing oxygen concentration in living cancer cells via confocal imaging and lifetime imaging. As the phosphorescence of the complexes were long-lived, the short-lived autofluorescence could be easily distinguished to improve the signal-to-noise ration and sensitivity.2. A non-convalent fluorescent/phosphorescent dual-emissive soft salt was designed and synthesized. The oxygen-sensitive anionic phosphorescent iridium complexes were linked to the oxygen-insensitive cationic conjugated fluorescence polymer through electrostatic interaction to construct the ratiomatric oxygen probe. The soft salt was further applied in the hypoxia imaging in living cells and showed high sensitive to oxygen, improved signal-to-noise ratio, low toxicity and good biocompatibility, which exhibited great potential in biosensing field.