A dual-functional fluorescent probe for sequential determination of Cu2+/S2- and its applications in biological systems.

ABSTRACT

A new acylhydrazine-derived Schiff base fluorescence probe DMI based on "ON-OFF-ON" fluorescence strategy was presented in this paper. Probe DMI could detect Cu2+ selectively and sensitively with dramatic fluorescence quenching in CH3OH-PBS (v/v = 37) mixed solution. Once the complex DMI-Cu2+ interacted with S2-, 10.67-folds fluorescence increase was induced via a displacement mechanism under the same experimental conditions. The corresponding detection limits for Cu2+ and S2- were calculated to be 1.52 × 10-8 M and 1.79 × 10-8 M, respectively. The structures of DMI and DMI-Cu2+ were systematically characterized by Job's plot analysis, ESI-MS, IR, X-ray diffraction and density functional theory calculations. Furthermore, fluorescence imaging in MCF-7 cells and zebrafish demonstrated the probe DMI could act as a useful tool to monitor and track intracellular Cu2+ and S2-, which was encouraged by remarkable fluorescence performance and low cytotoxicity. Importantly, the complex DMI-Cu2+ could be applied to detect corrupt blood samples, which could estimate the time of death.