Measuring zinc in living cells.: A new generation of sensitive and selective fluorescent probes

New fluorescent indicators with nanomolar to micromolar affinities for Zn 2+ have been synthesized in wavelengths from UV to the far red. The UV light-excited indicators are ratiometric. The visible wavelength indicators are non-ratiometric and exhibit large and pH-independent fluorescence increases with increasing zinc concentrations, with little to no sensitivity to physiologically relevant Ca 2+ concentrations. Experiments in neuronal and non-neuronal cell cultures show the new indicators to retain their sensitivity to and selectivity for zinc after conversion to cell-permeable forms.