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This study reports an activatable iridium(III) complex probe for phosphorescence/time-gated luminescence detection of cysteine (Cys) in vitro and in vivo. The probe, [Ir(ppy) 2 (NTY-bpy)](PF 6 ) [ppy: 2-phenylpyridine; NTY-bpy: 4-methyl-4'-(2-nitrovinyl)-2,2'-bipyridine], is developed by incorporating a strong electron-withdrawing group, nitroolefin, into a bipyridine ligand of the Ir III complex. The luminescence of the probe is quenched owing to the intramolecular charge transfer (ICT) process, but switched on by a specific recognition reaction between the probe and Cys. [Ir(ppy) 2 (NTY-bpy)](PF 6 ) shows high sensitivity and selectivity for Cys detection and good biocompatibility. The long-lived emission of [Ir(ppy) 2 (NTY-bpy)](PF 6 ) allows time-gated luminescence analysis of Cys in cells and human sera. These properties make it convenient for the phosphorescence and time-gated luminescence imaging and flow cytometry analysis of Cys in live samples. The Cys images in cancer cells and inflamed macrophage cells reveal that [Ir(ppy) 2 (NTY-bpy)](PF 6 ) is distributed in mitochondria after cellular internalization. Visualizations and flow cytometry analysis of mitochondrial Cys levels and Cys-mediated redox activities of live cells are achieved. By using [Ir(ppy) 2 (NTY-bpy)](PF 6 ) as a probe, in vivo sensing and imaging of Cys in D. magna, zebrafish, and mice are then demonstrated., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The progression of Alzheimer's disease (AD) is accompanied by the increase of copper ions (Cu2+) concentration and decrease of hydrogen sulfide (H 2 S) level in brain tissue, thus, reversible detection of Cu2+ and H 2 S is regarded as an important strategy for the diagnosis and intervention of AD. However, reliable tools for reversible tracking of Cu2+ and H 2 S and demonstrate their dynamic changes in AD are still lacking. Herein, this work developed a novel NIR Ir(III) complex-based probe, named NIR-Ir-DA, for reversible tracking of Cu2+ and H 2 S in AD cells and brain tissues. The newly prepared NIR luminescence probe exhibited fast response, high sensitivity and selectivity, good biocompatibility, which makes it to be used for reversible sensing of Cu2+ and H 2 S in multiple cycles in living cells and assessing AD progression in vitro and in vivo. Furthermore, using NIR-Ir-DA as a probe, we screened the theaflavin-3,3′-digallate (TF3) from polyphenols with an outstanding ability to reduce neuroinflammation, which would be greatly beneficial for AD therapy. These results indicated that NIR-Ir-DA could be a useful tool for understanding the role of "Cu2+-H 2 S seesaw" phenomenon in amyloid-β deposition, as well as for assessing AD progression and screening anti-AD drugs. [Display omitted] • A NIR Ir(III) complex probe for reversible detection of Cu2+ and H 2 S was developed. • Fast response, high sensitivity and selectivity towards Cu2+ and H 2 S was achieved. • Reversible detection of Cu2+ and H 2 S in multiple cycles in living nerve cells. • Assess AD progression in vitro and in vivo was successfully demonstrated. • Screen anti-AD drugs through visualization of the "Cu2+-H 2 S seesaw" phenomenon.. [ABSTRACT FROM AUTHOR]

This study reports an activatable iridium(III) complex probe for phosphorescence/time‐gated luminescence detection of cysteine (Cys) in vitro and in vivo. The probe, [Ir(ppy)2(NTY‐bpy)](PF6) [ppy: 2‐phenylpyridine; NTY‐bpy: 4‐methyl‐4′‐(2‐nitrovinyl)‐2,2′‐bipyridine], is developed by incorporating a strong electron‐withdrawing group, nitroolefin, into a bipyridine ligand of the IrIII complex. The luminescence of the probe is quenched owing to the intramolecular charge transfer (ICT) process, but switched on by a specific recognition reaction between the probe and Cys. [Ir(ppy)2(NTY‐bpy)](PF6) shows high sensitivity and selectivity for Cys detection and good biocompatibility. The long‐lived emission of [Ir(ppy)2(NTY‐bpy)](PF6) allows time‐gated luminescence analysis of Cys in cells and human sera. These properties make it convenient for the phosphorescence and time‐gated luminescence imaging and flow cytometry analysis of Cys in live samples. The Cys images in cancer cells and inflamed macrophage cells reveal that [Ir(ppy)2(NTY‐bpy)](PF6) is distributed in mitochondria after cellular internalization. Visualizations and flow cytometry analysis of mitochondrial Cys levels and Cys‐mediated redox activities of live cells are achieved. By using [Ir(ppy)2(NTY‐bpy)](PF6) as a probe, in vivo sensing and imaging of Cys in D. magna, zebrafish, and mice are then demonstrated. An activatable probe specific for Cys detection in the mitochondria of inflamed live cells and organisms is developed based on a unique IrIII complex. The probe, [Ir(ppy)2(NTY‐bpy)]+ [ppy: 2‐phenylpyridine; NTY‐bpy: 4‐methyl‐4′‐(2‐nitrovinyl)‐2,2′‐bipyridine], is capable of phosphorescence/time‐gated luminescence analysis of Cys in buffer, human sera, and live cells. Visualization of Cys‐mediated redox activities in mitochondria of inflamed cells and Cys in Daphnia magna, zebrafish, and mice are demonstrated (see figure). [ABSTRACT FROM AUTHOR]

An activatable iridium(III) complex probe for phosphorescence/time‐gated luminescence detection of cysteine (Cys) in vitro and in vivo is reported. The probe, [Ir(ppy)2(NTY‐bpy)][(PF6)] features large Stokes shift, long‐lived emission, good biocompatibility, high sensitivity and selectivity for Cys detection. Compound [Ir(ppy)2(NTY‐bpy)][(PF6)] is mitochondria targetable, which makes it convenient for the determination of Cys‐mediated redox activities in mitochondria. In vivo sensing and imaging of Cys in D. magna, zebrafish, and mice are demonstrated. More information can be found in the Full Paper by R. Zhang, W. Zhang, J. Yuan et al. on page 1498. [ABSTRACT FROM AUTHOR]