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Iridium(III) Anthraquinone Complexes as Two‐Photon Phosphorescence Probes for Mitochondria Imaging and Tracking under Hypoxia
Author(s) -
Sun Lingli,
Chen Yu,
Kuang Shi,
Li Guanying,
Guan Ruilin,
Liu Jiangping,
Ji Liangnian,
Chao Hui
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201600310
Subject(s) - phosphorescence , iridium , photochemistry , chemistry , mitochondrion , anthraquinone , singlet oxygen , fluorescence , biophysics , oxygen , biology , biochemistry , optics , organic chemistry , catalysis , physics
Abstract In the present study, four mitochondria‐specific and two‐photon phosphorescence iridium(III) complexes, Ir1 – Ir4 , were developed for mitochondria imaging in hypoxic tumor cells. The iridium(III) complex has two anthraquinone groups that are hypoxia‐sensitive moieties. The phosphorescence of the iridium(III) complex was quenched by the functions of the intramolecular quinone unit, and it was restored through two‐electron bioreduction under hypoxia. When the probes were reduced by reductase to hydroquinone derivative products under hypoxia, a significant enhancement in phosphorescence intensity was observed under one‐ ( λ =405 nm) and two‐photon ( λ =720 nm) excitation, with a two‐photon absorption cross section of 76–153 GM at λ =720 nm. More importantly, these probes possessed excellent specificity for mitochondria, which allowed imaging and tracking of the mitochondrial morphological changes in a hypoxic environment over a long period of time. Moreover, the probes can visualize hypoxic mitochondria in 3D multicellular spheroids and living zebrafish through two‐photon phosphorescence imaging.