A novel ratiometric fluorescent probe based on isophorone for hypochlorous acid imaging in cells and zebrafish

Hypochlorous acid (HOCl) dysregulation is implicated in inflammatory and neurodegenerative pathologies, necessitating precise tools for its real-time tracking. In this study, a novel isophorone-based ratiometric probe (IPH1) was developed for HOCl detection. IPH1 exploits HOCl-triggered oxidative cleavage of its p-aminophenyl ester moiety to release an aminoisophorone fluorophore, inducing a 90-nm ratiometric emission shift with a record 200-nm Stokes shift. IPH1 achieves ultrahigh sensitivity (LOD = 29 nM), selectivity, and rapid response (t_1/2 = 15 s). Its utility was validated through ratiometric imaging of exogenous/endogenous HOCl and MPO-derived HOCl in live cells, and real-time tracking of HOCl dynamics in zebrafish. The integration of isophorone's photophysical advantages with a rational trigger strategy provides a powerful tool for investigating HOCl biology.