A sensitive fluorescent probe for imaging biothiol in zebrafish

Due to their highly significant biological activities, in vivo monitoring biothiols, including glutathione (GSH), cysteine (Cys), and homocysteine (Hcy), draws great attention. Among them, GSH is the representative nonprotein thiol inside the cell with the high abundance, protecting cells from oxidative stress and toxins. In this work, we developed a fluorescent probe NI for sensitive mapping endogenous biothiol distribution in zebrafish. We used 1,8-naphthalimide scaffold as easy modifiable fluorophore and 2-thiophenecarbonxyl as recognition moiety. After the cleavage of ester bond by GSH addition, NI exhibited strong emission with large Stokes shift (110 nm) and its LOD is 0.120 μM. We also studied the difference of kinetic response of GSH over Cys and Hcy. Finally, the described probe was successfully applied in sensing endogenous biothiol in zebrafish, showing its potential utility in vivo imaging.