Two-photon fluorescent probes of biological Zn(II) derived from 7-hydroxyquinoline.

A new fluorescent probe for monitoring Zn(2+) was synthesized based on the structure of 7-hydroxyquinoline. Compared with 8-substituted quinolines, the new probe exhibited higher selectivity for Zn(2+) over Cd(2+). Its fluorescence enhancement (14-fold) and nanomolar range sensitivity (K(d) = 0.117 nM) were favorable toward biological applications. Experiments also showed that a cell-permeable derivative of the new probe was potentially useful for two-photon imaging in living cells.