Heterodinuclear Metal Complex Probe For Detecting Hypoxia

Molecular Oxygen (dioxygen) is one of the pivotal metabolites in aerobic organisms, and is imperative for maintaining the vital activity in almost all living cells. Oxygen deprivation (hypoxia), which is the result of inadequate oxygen supply, is closely connected with various diseases and occurs in tumor microenvironments. Hypoxia is a distinguished feature of malignant solid tumors, and the exploration of sensors which can accurately diagnose the oxygen level will be beneficial to estimate the malignant degree of tumor and subsequently execute more effective personalized treatment. Phosphorescence imaging of metal coordination complexes have attracted a great deal of attention because of their various advantages, which include high Stokes shifts, color-tunable luminescence, pronounced photostability, long emission lifetimes. Since the ground state of O2 is a triplet state, the emission of triplet excited state of the transition metal complexes can be quenched by collision with 02, enabling the metal complexes to monitor the oxygen content. However, majority of metal complex luminescence probes monitor the oxygen content with the intensity variation at one wavelength, which can be affected by the concentration of probes, exciting light intensity, and instrument performance. To overcome these problems, two metal complexes were synthesized with dual emission, and ratiometric monitored the oxygen variation in living systems.The heterodinuclear ruthenium and iridium metal complex [Ru(bpy)3-(CH2)10-Ir(F2ppy)2(bpy)]3+(RuIr) was employed to ratiometric monitor oxygen fluctuation in cells and mouse. There was efficient Forster resonance energy transfer(LRET) in [Ru(bpy)3-(CH2)10-Ir(F2ppy)2(bpy)]3+, and [Ir(F2ppy)2(bpy)]+ transfered majority of energy to [Ru(bpy)3]3+, making the luminescence of [Ir(F2ppy)2(bpy)]+ weak and insensitive to oxygen, while the luminescence of [Ru(bpy)3]3+ was stong and sensitive to oxygen. With increase in oxygen concentration, the luminescence of [Ir(F2ppy)2(bpy)]+ahnost unchanged, while that of [Ru(bpy)3]3+ gradually reduced, the probe could be used in ratiomeric detection oxygen variation. It was found that the probe can accurately respond to the fluctuation of oxygen concentration in living systems, demonstrating the probe has good biological application ability.A heterodinuclear near-infrared metal complex [Os(bpy)3-(CH2)12-Ir(F2ppy)2]3+ (OsIr) with dual emission was designed and synthesized. The cell experiments indicated that OsIr can penetrate into the cell, which suggested OsIr has the potential to monitor the oxygen variation in living systems.