Phosphorescent sensor for biological mobile zinc
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Author(s)
You, Youngmin
Lee, Sumin
Kim, Tae Hee
Ohkubo, Kei
Chae, Weon-Sik
Fukuzumi, Shunichi
Jhon, Gil-Ja
Nam, Wonwoo
Lippard, Stephen J.
Date Issued
October 2011
Journal
Journal of the American Chemical Society
Publisher
American Chemical Society (ACS)
Citation
You, Youngmin et al. “Phosphorescent Sensor for Biological Mobile Zinc.” Journal of the American Chemical Society 133.45 (2011): 18328–18342.
Version
Author's final manuscript
Abstract
A new phosphorescent zinc sensor (ZIrF) was constructed, based on an Ir(III) complex bearing two 2-(2,4-difluorophenyl)pyridine (dfppy) cyclometalating ligands and a neutral 1,10-phenanthroline (phen) ligand. A zinc-specific di(2-picolyl)amine (DPA) receptor was introduced at the 4-position of the phen ligand via a methylene linker. The cationic Ir(III) complex exhibited dual phosphorescence bands in CH[subscript 3]CN solutions originating from blue and yellow emission of the dfppy and phen ligands, respectively. Zinc coordination selectively enhanced the latter, affording a phosphorescence ratiometric response. Electrochemical techniques, quantum chemical calculations, and steady-state and femtosecond spectroscopy were employed to establish a photophysical mechanism for this phosphorescence response. The studies revealed that zinc coordination perturbs nonemissive processes of photoinduced electron transfer and intraligand charge-transfer transition occurring between DPA and phen. ZIrF can detect zinc ions in a reversible and selective manner in buffered solution (pH 7.0, 25 mM PIPES) with K[subscript d] = 11 nM and pK[subscript a] = 4.16. Enhanced signal-to-noise ratios were achieved by time-gated acquisition of long-lived phosphorescence signals. The sensor was applied to image biological free zinc ions in live A549 cells by confocal laser scanning microscopy. A fluorescence lifetime imaging microscope detected an increase in photoluminescence lifetime for zinc-treated A549 cells as compared to controls. ZIrF is the first successful phosphorescent sensor that detects zinc ions in biological samples.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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Creative Commons Attribution-Noncommercial-Share Alike 3.0
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DOI of Published Version
https://doi.org/10.1021/ja207163r
