title: Design and synthesis of a luminescent cyclometalated iridium(III) complex having N,N-diethylamino group that stains acidic intracellular organelles and induces cell death by photoirradiation.
abstract: Cyclometalated iridium(III) complexes have received considerable attention and are important candidates for use as luminescent probes for cellular imaging because of their potential photophysical properties. We previously reported that fac-Ir(atpy)(3)4 (atpy = 2-(5'-amino-4'-tolyl)pyridine) containing three amino groups at the 5'-position of the atpy ligand shows a maximum red emission (at around 600 nm) under neutral and basic conditions and a green emission (at 531 nm) at acidic pH (pH 3-4). In this Article, we report on the design and synthesis of a new pH-sensitive cyclometalated Ir(III) complex containing a 2-(5'-N,N-diethylamino-4'-tolyl)pyridine (deatpy) ligand, fac-Ir(deatpy)(3)5. The complex exhibits a considerable change in emission intensity between neutral and slightly acidic pH (pH 6.5-7.4). Luminescence microscopic studies using HeLa-S3 cells indicate that 5 can be used to selectively stain lysosome, an acidic organelle in cells. Moreover, complex 5 is capable of generating singlet oxygen in a pH-dependent manner and inducing the death of HeLa-S3 cells upon photoirradiation at 377 or 470 nm.
authors.affiliation: Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510 Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Moromizato
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Hisamatsu
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Suzuki
authors.forename: Yasuki
authors.initials: Y
authors.lastname: Matsuo
authors.forename: Ryo
authors.initials: R
authors.lastname: Abe
authors.forename: Shin
authors.initials: S
authors.lastname: Aoki
mesh_terms: D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D016923:Cell Death / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor; D005021:Ethylamines / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007495:Iridium / Q000737:chemistry*; D049408:Luminescent Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D008163:Luminescent Measurements; D015394:Molecular Structure; D015388:Organelles / Q000737:chemistry*; D055668:Photochemical Processes; D013329:Structure-Activity Relationship; D014407:Tumor Cells, Cultured; D014466:Ultraviolet Rays
chemical_list: D000970:Antineoplastic Agents; D005021:Ethylamines; D049408:Luminescent Agents; D007495:Iridium