A dipicolylamine-based fluorescent probe for visual detection of pyrophosphate using paper test strips and live cell imaging

Pyrophosphate (PPi) is a key biological anion in environmental monitoring and biological research, and its rapid and in situ detection is of great significance. In this work, a novel dipicolylamine-based fluorescent probe ZnL was designed and synthesized for highly selective and sensitive detection of PPi. In aqueous buffer under physiological pH, the probe exhibited an obvious turn-off fluorescence response toward PPi over other competing anions, with a limit of detection (LOD) of 0.13 μM. For practical on-site detection, ZnL was immobilized on filter paper to prepare portable paper test strips, enabling visual detection of PPi in lake water and bovine serum samples. Quantitative analysis using the G/B ratio showed good linearity, and the standard addition method gave satisfactory recoveries ranging from 97.81% to 116.69%. In addition, ZnL displayed low cytotoxicity and excellent cell permeability, allowing fluorescence imaging of exogenous PPi in MCF-7 cells. This integrated platform combining solution detection, paper-based visual sensing, and live-cell imaging demonstrates that ZnL serves as a powerful and reliable tool for rapid and in-situ monitoring of PPi in environmental and biological samples.