Fluorescent Biomass-Based Platform for Detection of ClO^- in Cells and Water-Soluble Systems

The generation and presence of excessive hypochlorous acid derivative ionic form (ClO^-) could cause various diseases, such as arteriosclerosis, DNA damage, and cardiovascular illness. It is a critical need to develop a highly sensitive sensor for reliable detection of ClO^- in cells and water-soluble systems. In this work, a hydroxyl group has been introduced into the compound 2-amino-3-(((E)-4-(2-(2-(2-hydroxyethoxy)ethyl)-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinolin-6-yl)benzylidene)amino)maleonitrile (NDC) to increase its solubility in water, at the same time, the hydrazone unit was designed as a specific recognition group for the "off-on" fluorescence probe of ClO^-. The probe NDC presents high selectivity, sensitivity, anti-interference, and low detection limit (67 nM) for ClO^-. The recognition mechanism that ClO^- breaks the C=N bond and forms the fluorescent compound 4-(2-(2-(2-hydroxyethoxy)ethyl)-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinolin-6-yl)benzaldehyde (ND-3) has been confirmed by time-of-flight mass spectrometry. The probe NDC presents a good performance in the actual test of water samples and can be designed as the test papers for the quick and convenient detection of ClO^- range from 0 to 1 μM. Moreover, the practical application was demonstrated by the successful imaging of endogenous and exogenous ClO^- in HeLa cells. Our fluorescent biomass-based platform opens vast possibilities for repeatability, sensitivity, and selectivity detection of ClO^- in cells and water-soluble systems.