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Published online: 15 October 2008 | doi:10.1038/nchina.2008.240

Fluorescent spectroscopy: Mercury exposed

Felix Cheung

Introduction

© (2008) Wiley Interscience

Mercury ions (Hg²⁺) can enter the human body through the skin and lungs, causing serious damage to the brain and kidneys. Fluorescence spectroscopy has become the tool of choice for sensing and imaging the biological effects of Hg²⁺ in living cells; the technique determines the degree of cellular damage by the change in the fluorescence intensity in cells that have been stained with fluorescent sensors. Yi Xiao at Dalian University of Technology and co-workers¹ have developed a sensor that can selectively detect amounts of Hg²⁺ on the scale of parts per billion.

Typical fluorescent sensors give off light with a single emission peak, the intensity of which can be affected by factors such as probe concentration. These sensors are therefore no good for quantitative measurements.

Xiao and co-workers developed a BODIPY–rhodamine system (BODIPY and rhodamine are both fluorescent sensors) that has two characteristic peaks. In the presence of Hg²⁺, the emission peak of the system changes from 514 nm (the characteristic peak of BODIPY; pictured top) to 589 nm (the characteristic peak of rhodamine; pictured bottom) through a mechanism known as fluorescence resonance energy transfer. The intensity ratio of the two characteristic peaks is independent of probe concentration and can be used for calibration prior to quantitative measurements.

The sensor can be dissolved in water as well as organic solvents — an important property that ensures the sensor gets inside the cell for intracellular fluorescent imaging. The researchers have shown that, in experiments, the probe can be used in the Hg²⁺ imaging of living cells.

The authors of this work are from:
State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian, China; Laboratory of Chemical Biology, East China University of Science and Technology, Shanghai, China.

Reference

1. Zhang, X., Xiao, Y. & Qian, X. A ratiometric fluorescent probe based on FRET for imaging Hg²⁺ ions in living cells. Angew. Chem. Int. Ed. doi: 10.1002/anie.200803246 (2008). | Article |