Red-Emissive Carbon Dots from Sustainable Biomass for Selective Sensing and Imaging of Hypochlorous Acid in Swimming Pool Water and Cells

Hypochlorous acid (HClO) detection is crucial for public health surveillance and the early diagnosis of related diseases. Currently, carbon dot (CD)-based fluorescent probes for HClO detection face issues such as insufficient green synthesis, a short fluorescence wavelength, and a lack of in-depth mechanistic studies. To address the above challenges, in this work, the biomass lotus leaf was used as the carbon source, and red fluorescent lotus leaf CDs (L-CDs) were green-synthesized. The probe exhibited high selectivity and sensitivity for HClO, with a detection limit of 0.44 μM. This method was successfully applied to detecting HClO in real water samples and the fluorescence imaging of endogenous and exogenous HClO in living cells. Through the combination of density functional theory calculations and experiments, the structure of L-CDs was speculated, and the oxidation and chlorination reactions with HClO were revealed from the perspectives of molecular structure and electron orbitals. This study introduced a new method for the sensitive detection of HClO, offering further insight into the mechanism of HClO detection by CDs.