Easily accessible and highly selective “Turn-on” fluorescent sensor for imaging cadmium in living cells

A new schiff base of phenothiazine derivative was designed for ratiometric sensing of Cd2+ selectively. Upon the addition of Cd2+ to the solution of phenothiazine derivative, the fluorescence intensity of it was enhanced in a linear fashion and the maximum fluorescence peak exhibited a blue shift from 575 nm to 525 nm. This ratiometric fluorescent sensor displays a very high sensitivity(detection limits were 0.34 and 1.0 μmol/L of Cd2+ using the visual fluorescence changes and UV-Vis changes, respectively), a rapid response time(<10 s) and high selectivity for Cd2+ over other transition metal ions. Moreover, the living cells image experiments also demonstrate the value of the sensor in fluorescent visualization of Cd2+ in the environmental and biological systems.