A water-stable zinc metal-organic framework as fluorescent probe for simultaneously sensing of glutathione and cysteine

Glutathione (GSH) and cysteine (Cys) have similar structures but play different roles in biological systems, so it is important to realize simultaneously and effectively detect them in biomedical field such as disease diagnose, etc. Herein, a water-stability and spindle shape zinc metal-organic framework (Zn-DTBA) with the ligand (2′-dithiodibenzoic acid, H2DTBA) has been successfully obtained for simultaneously detecting GSH and Cys. Cys can react with the disulfide bond in H2DTBA, thereby destroying the crystal structure of Zn-DTBA and quenching the fluorescence. GSH can act on the junction between the ligand and the metal node during the detection process, causing the collapse of Zn-DTBA structure and releasing Zn2+ ion and ligand. Therefore, Zn-DTBA has different fluorescence response for GSH and Cys, and the limit of detection (LOD) for the sensing of GSH and Cys was estimated to be 0.28 and 0.76 μM respectively. In further, Zn-DTBA can be successfully applied to detect Cys and GSH in serum as well, which is conducive to expand the application range of Zn-DTBA in practical detection. This investigation indicates that Zn-DTBA can be used as a potential fluorescent probe for the future biological studies of biothiols sensing.