Small-molecule NIR chemosensor for detecting hypochlorous acid within biosystem and visualizing cell deaths.

Hypochlorous acid (HOCl), an essential endogenous reactive oxygen species, is integral to various physiological and pathological processes. It is a crucial biomarker linked to inflammation and hepatic damage. The application of near-infrared fluorescence probes for in vivo biological imaging has increased recently, due to their little tissue damage and superior tissue penetration. This paper presents the synthesis of a novel near-infrared fluorescence probe, NS-Id, for the sensitive detection of HOCl. The NS-Id probe exhibits remarkable selectivity, elevated sensitivity (51 nM), and ultrafast response (20 s) to HOCl at an emission wavelength of 591 nm. Furthermore, it has been effectively utilized for visualizing HOCl in both cells and zebrafish. We also proved its capacity to monitor viscosity changes during cell deaths (apoptosis or ferroptosis) at an emission wavelength of 562 nm. These findings underscore the extensive applicability of NS-Id, establishing it as a potential chemical tool for real-time, selective monitoring of HOCl and viscosity.