Construction of a bi-functional ratiometric fluorescent probe for detection of endoplasmic reticulum viscosity and ONOO- in cells and zebrafish

Viscosity and ONOO- are two important factors that affect the physiological activities and functions of endoplasmic reticulum (ER). Therefore, the detection of changes in viscosity and ONOO- levels is important to the study of related physiological and pathological processes. In this work, a new bi-functional fluorescent probe WND-1 for simultaneous detection of ER viscosity and ONOO- fluctuations in different channels was developed. The novel probe has good viscosity responsiveness. With the increase of viscosity, the ratio of fluorescence intensity (I638/I453) showed a good linear correlation with viscosity log values. In addition, the probe also has the ability to specifically detect ONOO- changes, and its limit of detection (LOD) value was 0.93 μM. WND-1 also has the advantages of high anti-interference, low cytotoxicity, good ER localization and rapid response. Notably, it not only can be used for ratiometric fluorescence detection of viscosity in cells and zebrafish, but also can simultaneously detect viscosity and ONOO- in different channels. Additionally, with WND-1, we also found that ONOO- could induce an increase in viscosity in the ER. This may help to facilitate the study of related physiopathological processes.