Issue 5, 2016

Phosphorescent soft salt for ratiometric and lifetime imaging of intracellular pH variations

Abstract

In contrast to traditional short-lived fluorescent probes, long-lived phosphorescent probes based on transition-metal complexes can effectively eliminate unwanted background interference by using time-resolved luminescence imaging techniques, such as photoluminescence lifetime imaging microscopy. Hence, phosphorescent probes have become one of the most attractive candidates for investigating biological events in living systems. However, most of them are based on single emission intensity changes, which might be affected by a variety of intracellular environmental factors. Ratiometric measurement allows simultaneous recording of two separated wavelengths instead of measuring mere intensity changes and thus offers built-in correction for environmental effects. Herein, for the first time, a soft salt based phosphorescent probe has been developed for ratiometric and lifetime imaging of intracellular pH variations in real time. Specifically, a pH sensitive cationic complex (C1) and a pH insensitive anionic complex (A1) are directly connected through electrostatic interaction to form a soft salt based probe (S1), which exhibits a ratiometric phosphorescent response to pH with two well-resolved emission peaks separated by about 150 nm (from 475 to 625 nm). This novel probe was then successfully applied for ratiometric and lifetime imaging of intracellular pH variations. Moreover, quantitative measurements of intracellular pH fluctuations caused by oxidative stress have been performed for S1 based on the pH-dependent calibration curve.

Graphical abstract: Phosphorescent soft salt for ratiometric and lifetime imaging of intracellular pH variations

Supplementary files

Article information

Article type
Edge Article
Submitted
01 Dec 2015
Accepted
04 Feb 2016
First published
04 Feb 2016
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2016,7, 3338-3346

Phosphorescent soft salt for ratiometric and lifetime imaging of intracellular pH variations

Y. Ma, H. Liang, Y. Zeng, H. Yang, C. Ho, W. Xu, Q. Zhao, W. Huang and W. Wong, Chem. Sci., 2016, 7, 3338 DOI: 10.1039/C5SC04624F

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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