Integration of Cd:ZnS QDs into ZIF-8 for enhanced selectivity toward Cu2+detection

Metal-organic frameworks (MOFs) have been extensively studied for enhancing the performances of fluorescent probes based on the host-guest chemistry, while the selectivity enhancement of fluorescent probes through integration into MOFs is still relatively rare. In this work, Cd:ZnS QDs were integrated into ZIF-8 that could specifically interact with Cu(2+)for fluorescence sensing. The fluorescence of Cd:ZnS QDs was quenched by Cu(2+)based on cation exchange, while this phenomenon was also observed in the presence of Mn2+, Co(2+)and Ni2+. By contrast, only Cu(2+)induced the fluorescence quenching of Cd:ZnS QDs@ZIF-8 as a result of its specific interaction with ZIF-8. In addition, Cd:ZnS QDs@ZIF-8 displayed a fast response of 1 min and a low detection limit of 16 nM toward Cu2+, and moreover, it was successfully applied to detecting Cu(2+)in water samples with spiked recoveries ranging from 90.1 to 109.8%. These results indicate that integration into ZIF-8 is an efficient strategy to enhance the selectivity of fluorescent probes toward Cu2+.