Selective and Sensitive Detection of Heavy Metal Ions in 100% Aqueous Solution and Cells with a Fluorescence Chemosensor Based on Peptide Using Aggregation-Induced Emission

A fluorescent peptidyl chemosensor for the detection of heavy metal ions in aqueous solution as well as in cells was synthesized on the basis of the peptide receptor for the metal ions using an aggregation-induced emission fluorophore. The peptidyl chemosensor (1) bearing tetraphenylethylene fluorophore showed an exclusively selective turn-on response to, Hg2+ among 16 metal ions in aqueous buffered solution containing NaCl. The peptidyl chemosensor complexed Hg2+ ions and then aggregated in aqueous buffered solution, resulting in the significant enhancement (OFF-On) of emissions at around 470 nm. The fluorescent sensor showed a highly sensitive response to Hg2+, and about 1.0 equiv of Hg2+ was enough for the saturation of the emission intensity change. The detection limit (5.3 nM, R-2 = 0.99) of 1 for Hg2+ ions was lower than the maximum allowable level of He in drinking water by EPA. Moreover, the peptidyl chemosensor penetrated live cells and detected intracellular Hg2+ ions by the turn-on response.