Synthesis and living cell imaging of a novel fluorescent sensor for selective cupric detection

Copper is an important element indispensable for human life and health. Many copper-determining probes have been created for exploring its functional behavior in various cell types but few of them contains both fluorescent and colorimetric characters. In the present study, we developed a set of copper probes by synthesizing several novel thiophene-based Schiff bases in order to make a suitable sensor for quantifying and imaging copper in living cells. We find that the ligand FS-1 has a splendid selectivity and affinity toward Cu²⁺ among the common divalent metal ions. Living cell imaging show that FS-1 has a robust and repetitive fluorescence response in the presence of Cu²⁺ only in the cytosolic space of Hepg2 cell and not in the other cells examined. These data suggest that we have developed a new copper probe that can be used as a Cu²⁺ fluorescent and colorimetric sensor for in vivo and in vitro copper studies.