A novel core-shell upconversion nanoparticles@zirconium-based metal organic framework fluorescent nanoprobe for efficient continuous detection of trace methylene blue and ferrous ions

Herein, we have synthesized Gd2O3:Yb,[email protected]2 (UiO-66-NH2 represent a zirconium-based metal organic framework [Zr6O4(OH)4(ata)12], ata: 2‐aminoterephthalate) core-shell composites to develop an upconversion fluorescent nanoprobe for efficient detection of trace methylene blue (MB) and ferrous ions (Fe2+). Due to the fluorescence of the nanoprobe can be quenched by MB based on inner filter effect, but gradually recover when contact with ·OH, which is generated from the reaction between H2O2 and Fe2+, we have achieved the detection of Fe2+. The detection linear range is from 1.78 to 15.8 μM, and the limit of detection (LOD) is 0.071 μM. Besides, in this process, we also simultaneously realize the detection of MB. The linear range of MB turn-off detection is 0–42.6 μM, and the LOD is 0.41 μM. To our knowledge, no example of using upconversion fluorescence probe for continuous detection of trace MB and Fe2+ has been reported for now, and test results are superior compared with most reported Fe2+ probes. Moreover, the combinations of upconversion nanoparticles (UCNPs) and the metal-organic frameworks (MOFs) have enhanced the selectivity and sensitivity of the probe towards MB and Fe2+. Therefore, we believe the designed upconversion fluorescent nanoprobe is a promising efficient tool in detecting MB and diagnose Fe2+ related diseases in the future.