Highly Sensitive and Selective Fluorescent Probes for the Detection of HOCl/OCl^- Based on Fluorescein Derivatives

Developing highly sensitive and selective methods for HOCl/OCl^- detection is of significant interest. In this work, two fluorescent probes based on mono- and bis-formylated fluorescein, FN-1 and FN-2, were developed. The probes exhibit rapid response and high selectivity to HOCl/OCl^- over other reactive oxygen species (ROS)/reactive nitrogen species (RNS). Furthermore, a good linearity between the fluorescent intensity at 529 nm and the concentration of HOCl/OCl^- in the range 0-10 μM were presented. The probes FN-1 and FN-2 showed detection limits as low as 0.21 and 0.23 μM, respectively. The confocal laser scanning micrographs of HeLa cells confirmed cell permeability of the two probes and their abilities to detect HOCl/OCl^- in living cells. Compared to compound FN-1, FN-2 has lower background fluorescence and a higher speed of the reaction with HOCl/OCl^- which made it a better option for the detection of HOCl/OCl^- in aqueous solution.