A colorimetric and ratiometric fluorescent probe for mercury (II) in lysosome

Mercury is a highly hazardous and widespread heavy metal and can cause many severe health problems such as kidney failure, central nervous system damage with various cognitive and motor disorders, and even death. Efficient approach for the detection of mercury ion is very significant. In this work, a colorimetric and ratiometric fluorescent probe based on 4-chloro-7-nitrobenzo-2,1,3-oxadiazole (NBD-Cl) is developed by employing a photo-induced electron transfer mechanism. Furthermore, we were fortunate enough to obtain the single crystal structures before and after binding with Hg²⁺, which displays that two nitrogen atoms on amino and morpholine groups participate in the coordination and form a complex with a ratio of 2:2. And this probe displays a highly selective response to mercury (II) ions in an aqueous solution and possesses a distinguished capability for lysosome-targeting detection of Hg²⁺ without interferences in living cells. The results suggest that Hg²⁺-selective probe has good water-solubility, biocompatibility and cell-penetrability and can serve as an efficient tool for probing cellular toxicological actions that are related to Hg²⁺.