Phosphorescent Sensor for Biological Mobile Zinc
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- 作者：Youngmin You ; Sumin Lee ; Taehee Kim ; Kei Ohkubo ; Weon-Sik Chae ; Shunichi Fukuzumi ; Gil-Ja Jhon ; Wonwoo Nam ; Stephen J. Lippard
- 刊名：Journal of the American Chemical Society
- 出版年：2011
- 出版时间：November 16, 2011
- 年：2011
- 卷：133
- 期：45
- 页码：18328-18342
- 全文大小：1450K
- 年卷期：v.133,no.45(November 16, 2011)
- ISSN：1520-5126
文摘
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 CH3CN 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 Kd = 11 nM and pKa = 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.