Chromofluorescent Indicator for Intracellular Zn²⁺/Hg²⁺ Dynamic Exchange

The fluorescence of NABQ increases remarkably in the presence of Zn²⁺ and is quenched by Hg²⁺. As shown by confocal imaging, NABQ−Zn²⁺ can penetrate cells, where the bound Zn²⁺ is exchanged for Hg²⁺. This results in the concomitant export of Hg²⁺ from the cells, showing that NABQ can act as a Zn²⁺ carrier and as a Hg²⁺ extracting agent in living cells.