A dicyanomethylene-4H-pyran-based fluorescence probe with high selectivity and sensitivity for detecting copper (II) and its bioimaging in living cells and tissue.

Copper (Cu) plays a significant role in the process of oxygenic photosynthesis in living systems. The detection of copper ion (Cu2+) is valuable and meaningful for further investigating the functions of Cu2+ under physiological and pathological conditions. In this paper, a novel fluorescence probe DCM-Cu based on the near-infrared (NIR) fluorophore dicyanomethylene-4H-pyran (DCM) was designed for Cu2+ detection. The probe DCM-Cu possessed characteristic of "turn-on" fluorescent signal in the presence of Cu2+ through the enhanced ICT process. It exhibited satisfactory sensitivity and selectivity toward Cu2+. A good linear correlation was observed between the concentrations of Cu2+ and the fluorescence intensities at 700 nm. The detection limit (LOD) of DCM-Cu toward Cu2+ was calculated to be 2.54 × 10-8 M. Importantly, DCM-Cu was successfully applied in the detection of Cu2+ in living MCF-7 cells and tumor tissue with low cytotoxicity. Therefore, this probe would have the potential to monitor cellular Cu2+ in the living system and be applied to the diagnosis of related diseases.