A rhodamine B-based probe for the detection of HOCl in lysosomes

Highlights: • A novel fluorescent probe for HOCl was developed based on rhodamine B. • The probe could monitor HOCl changes with outstanding sensitivity, selectivity and rapid response. • The probe could target lysosome with little cytotoxicity. • The probe was successfully applied to image endogenous HOCl in RAW264.7 cells. -- Abstract: A rhodamine B-based derivative (RL1) was developed as a specific fluorescent probe for HOCl. Meanwhile, morpholine moiety was introduced into the probe. It was found that the probe could display highly selective, sensitive and naked-eye detection upon the addition of HOCl. And the detection limit (LOD) was calculated to be as low as 2.8 nM. Furthermore, cellular confocal microscopic studies revealed that the introduction of morpholine moiety realized the lysosome-targeting capability. Moreover, RL1 was successfully applied for the imaging of endogenous HOCl with low cytotoxicity. Therefore, all the desirable features made probe RL1 particularly suitable for HOCl detection in aqueous buffer solution samples as well as the bio-imaging applications.