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Issue 10, 2015

Cyclometalated iridium(iii) complexes as lysosome-targeted photodynamic anticancer and real-time tracking agents

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Abstract

Stimuli-activatable photosensitizers (PSs) are highly desirable for photodynamic therapy (PDT) to selectively demolish tumor cells. On the other hand, lysosomes are emerging as attractive anticancer targets. Herein, four cyclometalated iridium(III)–β-carboline complexes with pH-responsive singlet oxygen (1O2) production and lysosome-specific imaging properties have been designed and synthesized. Upon visible light (425 nm) irradiation, they show highly selective phototoxicities against cancer cells. Notably, complex 2 ([Ir(N^C)2(N^N)](PF6) in which N^C = 2-phenylpyridine and N^N = 1-(2-benzimidazolyl)-β-carboline) displays a remarkably high phototoxicity index (PI = IC50 in the dark/IC50 in light) of >833 against human lung carcinoma A549 cells. Further studies show that 2-mediated PDT induces caspase-dependent apoptosis through lysosomal damage. The pH-responsive phosphorescence of complex 2 can be utilized to monitor the lysosomal integrity upon PDT, which provides a reliable and convenient method for in situ monitoring of therapeutic effect and real-time assessment of treatment outcome. Our work provides a strategy for the construction of highly effective multifunctional subcellular targeted photodynamic anticancer agents through rational structural modification of phosphorescent metal complexes.

Graphical abstract: Cyclometalated iridium(iii) complexes as lysosome-targeted photodynamic anticancer and real-time tracking agents

Supplementary files

Article information


Submitted
01 Jun 2015
Accepted
22 Jul 2015
First published
22 Jul 2015

This article is Open Access
All publication charges for this article have been paid for by the Royal Society of Chemistry

Chem. Sci., 2015,6, 5409-5418
Article type
Edge Article

Cyclometalated iridium(III) complexes as lysosome-targeted photodynamic anticancer and real-time tracking agents

L. He, Y. Li, C. Tan, R. Ye, M. Chen, J. Cao, L. Ji and Z. Mao, Chem. Sci., 2015, 6, 5409 DOI: 10.1039/C5SC01955A

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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