A rhodamine based fluorescent probe for Hg2+ and its application to cellular imaging

A new rhodamine-based fluorescent probe (Rh-F) for detection of Hg2+ ions was synthesized, which could bind Hg2+ in aqueous ethanol (7:3, v/v) at pH 7.0 with detectable change in color and fluorescence. The response is based on a ring opening reaction and formation of a 1:1 complex, while ring-opening process of spirolactam enables large fluorescent enhancement and colorimetric change upon the addition of Hg2+. The response is reversible and linear in the range between 200 nM and 1000 nM, with a detection limit of 4.2 nM. Selectivity and competition experiments with various other metal ion revealed that Rh-F possesses highly selective fluorescent response to Hg2+. Furthermore, the probe was successfully applied to fluorescent imaging of Hg2+ in L-929 cells confirm that Rh-F can be used as a fluorescent probe for monitoring Hg2+ in living cells. (C) 2013 Elsevier B.V. All rights reserved.