A Water-Soluble Fluorescent Probe Based on Porphyrin Derivative 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 solution and living cells. 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 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.