Biocompatible Ir(III) Complexes as Oxygen Sensors for Phosphorescence Lifetime Imaging
Ilya S. Kritchenkov,
Anastasia I. Solomatina,
Daria O. Kozina,
Vitaly V. Porsev,
Victor V. Sokolov,
Marina V. Shirmanova,
Maria M. Lukina,
Anastasia D. Komarova,
Vladislav I. Shcheslavskiy,
Tatiana N. Belyaeva,
Ilia K. Litvinov,
Anna V. Salova,
Elena S. Kornilova,
Daniel V. Kachkin,
Sergey P. Tunik
Affiliations
Ilya S. Kritchenkov
Institute of Chemistry, St. Petersburg State University, Universitetskii av., 26, 198504 St. Petersburg, Russia
Anastasia I. Solomatina
Institute of Chemistry, St. Petersburg State University, Universitetskii av., 26, 198504 St. Petersburg, Russia
Daria O. Kozina
Institute of Chemistry, St. Petersburg State University, Universitetskii av., 26, 198504 St. Petersburg, Russia
Vitaly V. Porsev
Institute of Chemistry, St. Petersburg State University, Universitetskii av., 26, 198504 St. Petersburg, Russia
Victor V. Sokolov
Institute of Chemistry, St. Petersburg State University, Universitetskii av., 26, 198504 St. Petersburg, Russia
Marina V. Shirmanova
Institute of Experimental Oncology and Biomedical Technologies, Privolzhskiy Research Medical University, Minin and Pozharsky sq. 10/1, 603005 Nizhny Novgorod, Russia
Maria M. Lukina
Institute of Experimental Oncology and Biomedical Technologies, Privolzhskiy Research Medical University, Minin and Pozharsky sq. 10/1, 603005 Nizhny Novgorod, Russia
Anastasia D. Komarova
Institute of Experimental Oncology and Biomedical Technologies, Privolzhskiy Research Medical University, Minin and Pozharsky sq. 10/1, 603005 Nizhny Novgorod, Russia
Vladislav I. Shcheslavskiy
Institute of Experimental Oncology and Biomedical Technologies, Privolzhskiy Research Medical University, Minin and Pozharsky sq. 10/1, 603005 Nizhny Novgorod, Russia
Tatiana N. Belyaeva
Institute of Cytology of the Russian Academy of Sciences, Tikhoretsky av. 4, 194064 St. Petersburg, Russia
Ilia K. Litvinov
Institute of Cytology of the Russian Academy of Sciences, Tikhoretsky av. 4, 194064 St. Petersburg, Russia
Anna V. Salova
Institute of Cytology of the Russian Academy of Sciences, Tikhoretsky av. 4, 194064 St. Petersburg, Russia
Elena S. Kornilova
Institute of Cytology of the Russian Academy of Sciences, Tikhoretsky av. 4, 194064 St. Petersburg, Russia
Daniel V. Kachkin
Faculty of Biology, St. Petersburg State University, Universitetskaya emb., 7/9, 199034 St. Petersburg, Russia
Sergey P. Tunik
Institute of Chemistry, St. Petersburg State University, Universitetskii av., 26, 198504 St. Petersburg, Russia
Synthesis of biocompatible near infrared phosphorescent complexes and their application in bioimaging as triplet oxygen sensors in live systems are still challenging areas of organometallic chemistry. We have designed and synthetized four novel iridium [Ir(N^C)2(N^N)]+ complexes (N^C–benzothienyl-phenanthridine based cyclometalated ligand; N^N–pyridin-phenanthroimidazol diimine chelate), decorated with oligo(ethylene glycol) groups to impart these emitters’ solubility in aqueous media, biocompatibility, and to shield them from interaction with bio-environment. These substances were fully characterized using NMR spectroscopy and ESI mass-spectrometry. The complexes exhibited excitation close to the biological “window of transparency”, NIR emission at 730 nm, and quantum yields up to 12% in water. The compounds with higher degree of the chromophore shielding possess low toxicity, bleaching stability, absence of sensitivity to variations of pH, serum, and complex concentrations. The properties of these probes as oxygen sensors for biological systems have been studied by using phosphorescence lifetime imaging experiments in different cell cultures. The results showed essential lifetime response onto variations in oxygen concentration (2.0–2.3 μs under normoxia and 2.8–3.0 μs under hypoxia conditions) in complete agreement with the calibration curves obtained “in cuvette”. The data obtained indicate that these emitters can be used as semi-quantitative oxygen sensors in biological systems.
