title: Complexes of Ir(III)-octaethylporphyrin with peptides as probes for sensing cellular O2.
abstract: Ir(III)-porphyrins are a relatively new group of phosphorescent dyes that have potential for oxygen sensing and labeling of biomolecules. The requirement of two axial ligands for the Ir(III) ion permits simple linkage of biomolecules by a one-step ligand-exchange reaction, for example, using precursor carbonyl chloride complexes and peptides containing histidine residue(s). Using this approach, we produced three complexes of Ir(III)-octaethylporphyrin with cell-penetrating (Ir1 and Ir2) and tumor-targeting (Ir3) peptides and studied their photophysical properties. All of the complexes were stable and possessed bright, long-decay (unquenched lifetimes exceeding 45 μs) phosphorescence at around 650 nm, with moderate sensitivity to oxygen. The Ir1 and Ir2 complexes showed positive staining of a number of mammalian cell types, thus demonstrating localization similar to endoplasmic reticulum and ATP- and temperature-independent intracellular accumulation (direct translocation mechanism). Their low photo- and cytotoxicity allows intracellular oxygen to be probed.
authors.affiliation: Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria.
authors.forename: Klaus
authors.initials: K
authors.lastname: Koren
authors.forename: Ruslan I
authors.initials: RI
authors.lastname: Dmitriev
authors.forename: Sergey M
authors.initials: SM
authors.lastname: Borisov
authors.forename: Dmitri B
authors.initials: DB
authors.lastname: Papkovsky
authors.forename: Ingo
authors.initials: I
authors.lastname: Klimant
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000379:methods; D018929:Cell Culture Techniques; D056831:Coordination Complexes / Q000737:chemistry*; D006367:HeLa Cells; D006639:Histidine / Q000737:chemistry; D006801:Humans; D007495:Iridium / Q000737:chemistry*; D008163:Luminescent Measurements / Q000379:methods; D051379:Mice; D010100:Oxygen / Q000032:analysis / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry*; D013194:Staining and Labeling / Q000379:methods
chemical_list: D056831:Coordination Complexes; D010455:Peptides; D011166:Porphyrins; C488938:octaethylporphyrin; D007495:Iridium; D006639:Histidine; D010100:Oxygen