Cell imaging of dopamine receptor using agonist labeling iridium(III) complex

Kasipandi Vellaisamy, Guodong Li, Chung Nga Ko, Hai Jing Zhong, Sarwat Fatima, Hiu Yee Kwan, Chun Yuen Wong, Daniel Wai Jing Kwong*, Weihong Tan*, Chung Hang Leung*, Edmond Dik Lung Ma*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

104 Citations (Scopus)


Dopamine receptor expression is correlated with certain types of cancers, including lung, breast and colon cancers. In this study, we report luminescent iridium(iii) complexes (11-14) as intracellular dopamine receptor (D1R/D2R) cell imaging agents. Complexes 11 and 13, which are conjugated with a dopamine receptor agonist, showed superior cell imaging characteristics, high stability and low cytotoxicity (>100 μM) in A549 lung cancer cells. siRNA knockdown and dopamine competitive assays indicated that complexes 11 and 13 could selectively bind to dopamine receptors (D1R/D2R) in A549 cells. Fluorescence lifetime microscopy demonstrated that complex 13 has a longer luminescence lifetime at the wavelength of 560-650 nm than DAPI and other chromophores in biological fluids. The long luminescence lifetime of complex 13 not only provides an opportunity for efficient dopamine receptor tracking in biological media, but also enables the temporal separation of the probe signal from the intense background signal by fluorescence lifetime microscopy for efficient analysis. Complex 13 also shows high photostability, which could allow it to be employed for long-term cellular imaging. Furthermore, complex 13 could selectively track the internalization process of dopamine receptors (D1R/D2R) in living cells. To the best of our knowledge, complex 13 is the first metal-based compound that has been used to monitor intracellular dopamine receptors in living cells.

Original languageEnglish
Pages (from-to)1119-1125
Number of pages7
JournalChemical Science
Issue number5
Early online date19 Dec 2017
Publication statusPublished - 7 Feb 2018

Scopus Subject Areas

  • Chemistry(all)


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