A water-soluble fluorescent probe based on porphyrin derivatives for Cu2+ detection in aqueous solution and living cells†

Accurately tracing copper ions (Cu²⁺) is critically important in the fields of environmental protection and human body monitoring. Excessive intake of Cu²⁺ not only easily leads to diseases, but also affects human health. Therefore, it is particularly important to find an easy-to-use, effective, and highly selective probe for in situ Cu²⁺ detection in living cells. Herein, a water-soluble porphyrin derivative (WSPD) was successfully synthesized and used as a highly sensitive and selective fluorescent probe for detecting Cu²⁺ in aqueous solutions and living cells. The WSPD possesses good water solubility and photostability, large Stokes shift (>200 nm), appreciable red fluorescence and low cytotoxicity. The fluorescence signal could be rapidly quenched by Cu²⁺ with high selectivity due to the strong affinity of Cu²⁺ to the porphyrin core of the WSPD. The proposed fluorescent probe exhibited a low detection limit of 6.43 nM and a fast response time (<5 min) for Cu²⁺ detection in aqueous solution. Furthermore, it is successfully employed for the fluorescence imaging of intracellular Cu²⁺ in living cells, demonstrating its great potential in the fields of biomedical imaging and biosensing.