Synthesis And Application Of Optical Oxygen Probe Based On Ruthenium Containing Conjugated Polymer

Oxygen is an important energy source and signaling molecule in creatures.Hypoxia is related to many diseases,especially in tumor tissues.It plays an important role in the prediction and decision-making for chemoresistance,angiogenesis,radioresistance,vasculogenesis,invasiveness,metastasis and resistance to cell death.Optical oxygen probes are the best methods to solve real-time biomedical imaging sensing in vitro and in vivo.Among them,the transition metal complex as the core of optical sensing develops fast and is the most widely used detection method in the past decade.Compared with iridium,platinum and metal porphyrin complexes,although the ruthenium complexes have inferior luminous intensity or luminescence lifetime,they have been studied a lot because of their stablility and easy metabolism.Therefore,the synthesis of ruthenium complex oxygen probe with excellent optical properties and oxygen sensitivity has an important application prospect.In this article,we innovatively designed and synthesized a main chain conjugated polymer optical oxygen probe with polyfluorene as the energy donor and tris?2,2'-bipyridyl?ruthenium as the oxygen sensitive core.The high absorption factor of polyfluorene and the coordination change of the complex by main chain polymerization greatly improved the optical performance of the ruthenium complex.The main content of the paper is as follows:1.Combining the design of the synthetic route of the ruthenium containing main chain conjugated polymer with the synthetic experiment results,it was found that the synthesized polymer had excellent energy transfer effect and was free of aggregation-caused-quenching only when the ruthenium complex monomer was polymerized onto the polyfluorene?-conjugated main chain by Suzuki cross-coupling at a one-to-one feed ratio.The structure was verified by FT-IR and ¹H NMR.The number-average molecular weight of the polymer was 8604 and the degree of polymerization was 9.2.Optical characterization discovered that comparing with the small molecule of ruthenium terpyridine,the polymer's emission intensity under 380nm excitation increased by 3.65 times and its quantum yield increased to 8.19%.Besides,the luminescence lifetime increased from 145ns to 250ns and the absorption was widened.The results above all proved the existence of energy transfer and the greatly improved luminous performance of ruthenium complex.3.After Ru?bpy?₃-PFO was prepared as a optical oxygen probe by reprecipitation method,it had a spherical morphology and the average particle size was 90 nm.The optical properties did not change much.The oxygen sensitivity factor after fitting the change of the luminescence peak intensity with the dissolved oxygen concentration to the Stern-Volmer curve was 0.10702,which was significantly higher than that of the small molecule and the branched-coordinated ruthenium complex.It was found that the emission intensity of the probe was less affected by temperature and that the repeatability of responsiveness was great.Its excellent hypoxic imaging ability has potential application value for cancer diagnosis.