Multifunctional Fluorescent Nanoprobe for Sequential Detections of Hg²⁺ Ions and Biothiols in Live Cells

Herein, we report an amphiphilic fluorescent probe consisting of a dansyl fluorophore as a reporter and a hydrophobic cetyl chain bridged by a triazole unit. The cetyl-based probe can self-assemble to form nanoaggregates in aqueous solution, as confirmed by Tyndall effect, dynamic light scattering (DLS), and transmission electron microscopy (TEM) measurements. This probe exhibited an “on–off” fluorescence quenching response toward Hg 2+ ions in aqueous solution over other tested metal ions. In contrast, the analogous methyl-based probe barely exhibits Hg 2+ ion sensing behavior under the same conditions. Moreover, the resulting complex of the cetyl-based probe and Hg 2+ ( 1 -Hg 2+, 1:1 stoichiometry) exhibited an efficient fluorescence “off-on” sensing for thiol-containing amino acids, including cysteine (Cys), homocysteine (Hcy), and glutathione (GSH). This nanoprobe exhibited minimal cytotoxicity with excellent cell permeability and was efficiently tested for the imaging of intracellular Hg 2+ and cysteine in live cells.