A small molecule modified UiO series MOFs for simultaneous detection of Fe³⁺ and Zn²

Iron and zinc are two metal ions with important roles in biology, industry and the environment, however, the excess or deficiency of both Fe³⁺ and Zn²⁺ can have negative effects on organisms and environment. Therefore, the development of efficient method for simultaneous detection of Fe³⁺ and Zn²⁺ provides timely information on metal content, simplifies operations and improves efficiency. In this work, a small molecule (COOH-BPEA) of recognizing Zn²⁺ modified the four metal-organic-framework (MOF) (UiO-66-X(66, OH, NH₂ and OH/NH₂)) was developed for the simultaneous detection of Fe³⁺ and Zn²⁺. The fluorescence signal of the small molecule is enhanced by small molecule chelating Zn²⁺ to block the photoinduced electron transfer (PET) effect. The fluorescence signals of the UiO series MOFs were quenched through Fe³⁺ with electron transfer and static quenching effect (SQE). It's worth mentioning that the emission wavelengths of the small molecules and MOFs did not interfere with each other. The UiO-66-NH₂@BPEA with optimal performance was selected by fluorescence spectra for the detection of Fe³⁺ and Zn²⁺ with detection limit of 0.175 μM and 0.021 μM, respectively. The nanoprobe provides a fast response (less than 1 min) for both Fe³⁺ and Zn²⁺. Finally, we applied it to the simultaneous detection of Fe³⁺ and Zn²⁺ in environmental water, human serum and cell lysates.