Photocontrollable Fluorogenic Probe for Visualizing Near-Membrane Hypochlorite in Live Cells

Hypochlorous acid or hypochlorite (HClO/ClO⁻) near membrane is one of the most critical reactive oxygen species (ROS). Herein, a photocontrollable fluorogenic probe for directly detecting ClO⁻ near membrane has been designed and synthesized. This probe HOCMem was constructed based on fluorescein by incorporation of a photolabile group (nitrobenzyl group), membrane-anchoring unit (cholesterol) and ClO⁻-sensitive moiety (benzoyl group). Upon the UV irradiation, the probe exhibited a significantly increased emission at 520 nm in the presence of ClO⁻. However, no fluorescence was observed with the treatment of only UV irradiation or ClO⁻. In addition, this new probe displayed a good linear relationship with the concentration of ClO⁻ ranged from 1 to 50 μM with a detection limit of 260.77 nM, as well as excellent selectivity for ClO⁻ over other analytes. Furthermore, cell-based experiments showed the low cytotoxicity of this probe and its capacity for directly detecting near-membrane ClO⁻ with light switching on/off.