A Novel Ratiometric Fluorescent Probe Based on Ortho-Position Oxime Functionalized Perylene Diimide for Supersensitive HClO/ClO^– Recognition and Bioimaging in Cells and Zebrafish

Hypochlorous acid (HClO) or hypochlorite (ClO^-) not only is a common weak acid in daily life but also serves as a disinfectant and a key component of bleaching powder. Simultaneously, HClO/ClO^- can also participate in many pathological processes as a kind of reactive oxygen species. To address the limitations in HClO/ClO^- detection, we developed <b>PDI-O</b>, an ultrasensitive, rapid-response, and highly selective fluorescent probe, through rational molecular engineering of a perylene diimide scaffold and oxime as the recognition site. We systematically evaluated the photophysical properties and HClO/ClO^- response performance of <b>PDI-O</b> through comprehensive spectral characterization. The probe demonstrates remarkable analytical metrics: (1) dual detection modes by UV-vis and fluorescence; (2) ultrahigh sensitivity with a subnanomolar detection limit (5 pM); (3) exceptional selectivity and anti-interference ability against 16 common interferences, including ions and reactive oxygen/nitrogen analogs; (4) rapid response speed (7.5 s); (5) wide linear range (0-8.0 μΜ); and (6) convenient visual detection toward smartphone-based RGB analysis. Notably, <b>PDI-O</b> exhibits dual-function bioimaging capabilities: it enables real-time discrimination of live/dead mammalian cells while achieving zebrafish larval imaging of HClO/ClO^-. This novel ratiometric fluorescent probe establishes a new paradigm for developing precision biosensors to unravel hypochlorite-related pathophysiological cascades.