Rosamine-based fluorescent sensor with femtomolar affinity for the reversible detection of a mercury ion.

A Hg(2+)-selective fluorescent sensor, RosHg, has been developed based on a rosamine platform. RosHg exhibited a ∼20-fold increase in fluorescence emission upon binding with Hg(2+), and the enhanced fluorescence was immediately decreased when glutathione was added to a solution of the Hg-RosHg complex. The dissociation constant for the Hg(2+) complex was determined to be 0.10 fM by using a set of Hg(2+)/Mg(2+)/ethylenediaminetetraacetic acid buffer solutions. Confocal microscopy experiments demonstrated that this sensor can monitor changes of the Hg(2+) level in the mitochondria of living cells.