Coumarin-Based Reversible Fluorescent Probe for Selective Detection of Cu²⁺ in Living Cells

Copper ion plays an important role in many biological processes in human body. H₂S is considered as the third gasses transmitter after carbon monoxide and nitric oxide. Here a novel ICT-based fluorescent ON-OFF-ON probe for Cu²⁺ and H₂S detection was developed. Selectivity and sensitivity of probe was confirmed in aqueous Tris-HCl buffer (10 mM, pH 7.4, containing 90% acetonitrile). Probe DF-CU shows high selectivity over other analytes. The degree of fluorescence quenching is linearly associated with the concentration of Cu²⁺ (R² = 0.9919). The limit of detection (LOD, calculated according to the 3σ/slope) for Cu²⁺ was 6.4 μM. Probe can work in almost all pH. The probe shows a very fast response to Cu²⁺ (within 10 s). Its response to copper ion could be reversed by H₂S. The complex of probe with Cu²⁺ could be used for H₂S detection. Furthermore, this ON-OFF-ON fluorescent probe successfully applied in the living cells for the detection of Cu²⁺ and H₂S.