Dual-Phosphorescent Iridium(III) Complexes Extending Oxygen Sensing from Hypoxia to Hyperoxia

Abstract

Hypoxia and hyperoxia, referring to states of biological tissues in which oxygen supply is in sufficient and excessive, respectively, are often pathological conditions. Many luminescent oxygen probes have been developed for imaging intracellular and in vivo hypoxia, but their sensitivity toward hyperoxia becomes very low. Here we report a series of iridium­(III) complexes in which limited internal conversion between two excited states results in dual phosphorescence from two different excited states upon excitation at a single wavelength. Structural manipulation of the complexes allows rational tuning of the dual-phosphorescence properties and the spectral profile response of the complexes toward oxygen. By manipulating the efficiency of internal conversion between the two emissive states, we obtained a complex exhibiting naked-eye distinguishable green, orange, and red emission in aqueous buffer solution under an atmosphere of N2, air, and O2, respectively. This complex is used for intracellular and in vivo oxygen sensing not only in the hypoxic region but also in normoxic and hyperoxic intervals. To the best of our knowledge, this is the first example of using a molecular probe for simultaneous bioimaging of hypoxia and hyperoxia.

Photoacoustic Imaging: Contrast Agents and Their Biomedical Applications

“…A lack of oxygen supply leads to hypoxia, which damages physiological function and is the pathological feature of many diseases, including cancer and ischemia . Therefore, sensing of hypoxia could guide the therapeutic regimen and could be used as a predictor of patient prognosis . Chan and co‐workers developed a hypoxia‐responsive PA‐imaging contrast agent with a N‐oxide trigger (HyP‐1), which can be reduced in conditions without oxygen, while the reduction of Hyp‐1 (absorption at 670 nm) produces a different spectral product (Red‐Hyp‐1; absorption at 760 nm) easily identified by PA imaging ( Figure A) .…”

A New Facial Homoleptic Tris‐cyclometalated Iridium(III) Complex with Oxygen‐bridged Triarylamine Units

“…In the last few decades, transition metal complexes have been widely used in the field of light‐emitting materials . In particular, phosphorescent iridium(III) complexes as optical functional materials have attracted a lot of attentions owing to their diverse chemical structures and excellent luminous properties . Especially, homoleptic tris‐cyclometalated phosphorescent iridium(III) complexes with facial structure tend to have more stable structures and better optical properties than other complexes, such as the classic facial phosphorescent iridium(III) complex fac ‐Ir(ppy) 3 (ppy=2‐phenylpyridine) (scheme ) is a famous green light emitting material, and its derivatives are very widely used.…”

Novel designed azo substituted semi-cyanine fluorescent probe for cytochrome P450 reductase detection and hypoxia imaging in cancer cells

“…Groups such as aromatic nitro group, azo group and quinone group have been applied in the designing of various hypoxic activated uorescent probes. [9][10][11][12] So far, various methods have been applied in the detection of hypoxia in the clinic, including positron emission tomography/ computed tomography (PET/CT), electron paramagnetic resonance imaging (EPRI) and so on. [13][14][15] Because it is non-invasive, and has high sensitivity and high spatiotemporal resolution, uorescence imaging is still an ideal method for hypoxia detection.…”