Issue 2, 2016

An ultrasensitive near-infrared ratiometric fluorescent probe for imaging mitochondrial polarity in live cells and in vivo

Abstract

Mitochondrial polarity is a crucial characteristic of these indispensable organelles, and tremendously impacts cellular events. Herein, we describe a new mitochondria-targeting fluorescent probe MCY-BF2 that is singularly sensitive and specifically responsive to mitochondrial polarity. The pull–push system in the conjugated structure of MCY-BF2 is responsible for the polarity-ultrasensitivity due to the excited state intramolecular charge transfer (ICT). By combining with cardiolipin, MCY-BF2 preferentially accumulates in mitochondria. Because the fluorescence emission wavelengths exhibit an obvious red-shift with increasing media polarity, the fluorescence intensity ratio at two different wavelengths versus the solvent dielectric constant can quantify the mitochondrial polarity. Experimental results demonstrate that the fluorescent intensity of MCY-BF2 in a non-polar solvent, dioxane, is 120 times higher than that in a polar solvent, dimethyl sulfoxide. As the first near-infrared (NIR) and most sensitive fluorescent imaging probe for polarity, MCY-BF2 can locate exclusively in mitochondria in various cells and discriminate polarity differences between normal and cancer cells. Also, the intrinsic polarity variance at different developmental stages in Caenorhabditis elegans (C. elegans) was reported here for the first time. Interestingly, the embryonic development stage has a more non-polar environment with a dielectric constant of 7.20, and in contrast the polarity at the young adult stage changes to 10.07. In addition, in vivo imaging results suggest that the tumor tissues of mice have an obviously lower polarity than that in normal tissues. Altogether, the merits of the NIR property, high sensitivity and moderate Stokes shift all greatly promote the accuracy of imaging. This probe will be a promising tool for studying biological processes and the pathological mechanism of polarity-related diseases.

Graphical abstract: An ultrasensitive near-infrared ratiometric fluorescent probe for imaging mitochondrial polarity in live cells and in vivo

Supplementary files

Article information

Article type
Edge Article
Submitted
28 Oct 2015
Accepted
19 Nov 2015
First published
23 Nov 2015
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, 1588-1593

An ultrasensitive near-infrared ratiometric fluorescent probe for imaging mitochondrial polarity in live cells and in vivo

H. Xiao, P. Li, W. Zhang and B. Tang, Chem. Sci., 2016, 7, 1588 DOI: 10.1039/C5SC04099J

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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