A Ratiometric Fluorescent Detection Platform Using G‐CDs@[Ru(bpy)₃]²⁺ for the Specific Detection of Hypochlorite and Live Cell Imaging

Hypochlorite (ClO − ), an essential reactive oxygen species (ROS) in physiological processes, is identified to be closely connected with oxidative stress and related diseases. Meanwhile, ClO − is a commonly‐used disinfector for water treatment, and in public places, under acidic conditions, it's easily decomposed into hypertoxic chlorine gas. Since the strong oxidizing property of ClO − , many oxidizing agents may disturb the ClO − detection. Specific and accurate detection of ClO − with superior sensitivity is a challenge. In this work, a sensing platform for rapid, sensitive, and specific ClO − detection is constructed using green fluorescent carbon dots (G‐CDs), with a linear detection range of 0.5–11 µ m and a detection limit of 0.233 µ m . Moreover, introducing a red fluorescent tripyridinium ruthenium ([Ru(bpy) 3 ] 2+ ) as a reference, a ratiometric fluorescence nanoprobe G‐CDs@[Ru(bpy) 3 ] 2+ is prepared and shows favorable intracellular imaging of exogenous and endogenous ClO − . With G‐CDs@[Ru(bpy) 3 ] 2+ ‐based test paper microarrays and a color recognition APP, a smartphone‐based sensing system for point‐of‐care testing of ClO − is also fabricated. In summary, this work proposed a versatile and economical smartphone‐based sensing system that featured reliability and simplicity, and suggested its potential applications in environmental water quality monitoring and live cell imaging.