Chlorination-induced pKa decrease: an improved strategy to design ratiometric hypochlorite fluorescent probes with ideally high selectivity

Abstract

Based on the selective ClO⁻-triggered chlorination reaction and the subsequent pK_a decrease of phenols, a new strategy was developed for rationally designing ratiometric ClO⁻ fluorescent probes with high selectivity. By investigating the fluorescence responses of 6-cyano-2-naphthol toward ClO⁻ and the pK_a-dependent response mechanism, we developed a rapid, sensitive and selective two-photon ratiometric fluorescent probe, Naph-DFOB, to detect ClO⁻. This probe displayed a ratiometric fluorescence change (from 509 nm to 628 nm) toward ClO⁻ and was successfully applied to image intracellular ClO⁻ in living cells with two-photon excitation. Using Naph-DFOB as a useful tool, the investigation of lipopolysaccharide (LPS)-induced acute lung injury in a mouse model was effectively performed.