Highly water-soluble BODIPY-based fluorescent probes for sensitive fluorescent sensing of zinc(ii)

A zinc(ii) chelator bis(pyridin-2-ylmethyl)amine moiety has been incorporated into three different highly water-soluble dyes, 2-formyl-BODIPY, 2,6-diformyl BODIPY, and 2,6-diformyl-1,7-distyryl-BODIPY, at 2-position and 2,6-positions, resulting in three highly water-soluble BODIPY-based fluorescent probes A, B and C for zinc(ii) ions. Fluorescent probes A and B display sensitive fluorescent responses with significant fluorescence enhancement to zinc(ii) ions at pH 7.0 while fluorescent probe C shows two distinct measurable fluorescent signals at 521 nm and 661 nm, and displays ratiometric responses to zinc(ii) ions with fluorescence quenching at 661 nm and fluorescence enhancement at 521 nm. These three fluorescent probes exhibit excellent sensitive and selective responses to zinc(ii) ions. Intracellular zinc(ii) concentration could be monitored in cancer cells with fluorescent probe C.