Highly sensitive and fast responsive ratiometric fluorescent probe for Cu2+ based on a naphthalimide-rhodamine dyad and its application in living cell imaging

Based on fluorescent resonance energy transfer (FRET), we developed a ratiometric fluorescent probe 1 for sensing Cu2+. As expected, probe 1 exhibited high selectivity and excellent sensitivity in both absorbance and fluorescence detection of Cu2+ in aqueous solution. A significant color change from pale yellow to pink could be observed, enabling naked-eye detection of Cu2+. Furthermore, fluorescence imaging experiment of Cu2+ in living MGC-803 cells demonstrated its value of practical applications in biological systems.