An ultra-rapid and highly sensitive fluorescent probe for HClO: dual-responsive detection, cellular imaging and...

Hypochlorous acid (HClO), a key reactive oxygen species (ROS), plays a dual role in biological systems: it serves as an essential molecule in immune defense, yet it can also induce pathological damage under conditions of metabolic imbalance. Therefore, HClO detection, particularly at extremely low concentration in organisms, is of great importance. In this study, we developed a novel naphthalimide-derived fluorescent probe, named NAP-S, for HClO detection by leveraging the intramolecular charge transfer (ICT) property. The probe exhibited record-breaking response time (572 ms), high sensitivity (with a detection limit of 8.3 nM), strong anti-interference capability, excellent selectivity, robust stability, and broad pH adaptability (2-14). Moreover, it has been successfully applied to determine HClO concentration in real water samples and for smartphone-based analysis. Bioimaging experiments further demonstrated that NAP-S can be effectively used to monitor both endogenous and exogenous HClO levels in living HeLa cells and zebrafish, highlighting its potential for biological applications.