Dual-functional colorimetric fluorescent probe for sequential Cu2+ and S2− detection in bio-imaging

It is highly indispensable to detect Cu2+ and S2− because of its vital role in living organisms and the environment. In this work, a novel “on-off-on” coumarin-based colorimetric fluorescent probe L for sequential recognition of Cu2+ and S2– was strategically designed and synthesized. It displays low detection limit measured to be 2 × 10−8 M and 6 × 10−8 M respectively for Cu2+ and S2– with high selectivity and excellent sensitivity. In addition, an appropriate broad pH of 4–10 allows probe L to be applied to the biological window, and MTT experiments show that probe L has negligible cytotoxicity, which demonstrate it can be employed to determine Cu2+ and S2– in A375 cells.