Functionalized Metal-Organic Framework UiO-66-NH-BQB for Selective Detection of Hydrogen Sulfide and Cysteine

Hydrogen sulfide (H₂S) is an important signaling molecule related to many diseases. Thus, H₂S has a great impact on the pathological and physiological processes in biological systems. Cysteine (l-Cys) is a building block for proteins and important metabolites. To understand their roles in the physiological metabolic procedures, the measurement of the H₂S level and identifying cysteine in the biological system is significant. In this study, through the functionalization of UiO-66-NH₂ by 4-(2,2-dicyanoethenyl)benzoic acid (BQB), a novel UiO-66-NH-BQB is successfully synthesized and used as a fluorescence probe to recognize and detect H₂S and l-Cys. The fluorescence signals of the probe are enhanced great when it is exposed to H₂S or cysteine molecules; thus, it is able to determine quantificationally the H₂S concentration in an aqueous solution. The detection limitation of the UiO-66-NH-BQB to H₂S concentration is found to be as low as 1.74 μM. The developed fluorescent probe based on UiO-66-NH-BQB displays a high selectivity and excellent biocompatibility, which is very promising for recognition and sensing of biothiols in organisms.