Dicyanostilbene-derived two-photon fluorescence probe for lead ions in live cells and living tissues

A novel two-photon fluorescence probe for Pb(2+) derived from 4-methyl-2,5-dicyano-4'-amino stilbene as a two-photon fluorophore and bis[2-(2-aminophenylsulfanyls)ethyl]amine as a novel Pb(2+) ligand was developed. The probe possesses small molecule size, large two-photon absorption cross-section (1020 GM), noncytotoxic effect, long-wavelength emission at 609 nm, large Stokes shift (209 nm), excellent photostability, moderate water-solubility, good cell-permeability, and pH-insensitivity in the biologically relevant pH range. The probe can selectively detect Pb(2+) ions in live cells and living tissues without interference from other metal ions and the membrane-bound probes, and its quenching constant (K(SV)(TP)) is 7.58×10(5) M(-1).