Porphyrin-Based Fluorescent Probe for Nanomolar Detection of Cu2+ and Ni2+ Ions.

Copper is an indispensable trace element for maintaining metabolic homeostasis; however, the dysregulation and subsequent accumulation of Cu2+ are critically linked to neurodegenerative pathologies, including Alzheimer's disease in humans. Consequently, the development of robust analytical tools for Cu2+ monitoring is of paramount importance. Here, we report a 2,2'-dipicolylamine porphyrin (DPAP)-based fluorescent sensor designed for the precise detection of metal cations. Photophysical investigations reveal that DPAP operates via a rapid turn-off fluorescence mechanism, achieving high-performance sensing in the parts-per-million range. Notably, the probe demonstrates exceptional sensitivity with detection limits of 26.3 nM for Cu2+ and 34.8 nM for Ni2+. Interference studies demonstrated the selectivity of DPAP for Cu2+ over a diverse range of competing metal ions such as Na+, Ag+, Ni2+, Cr3+, Pb2+, Al3+, Fe2+, Cd2+, and Zn2+. These results indicate that DPAP is a sensitive and selective probe suitable for copper ion detection.