Core‐Shell Upconversion Nanoparticle@Metal–Organic Framework Fluorescent Nanoprobes for the Detection of Ferric Ions and Ferrous Ions

Abstract In this study, we report a core‐shell fluorescent nanoprobe consisting of upconversion nanoparticles (UCNPs) NaGdF 4 : Yb 3+ , Er 3+ and metal‐organic frameworks (MOFs) ZIF‐8. ZIF‐8 can specifically bind to ferric ions (Fe 3+ ) to change the ultraviolet‐visible absorption spectrum of the probe, as a result the fluorescence of the probe was quenched and achieve the detection of Fe 3+ . At the same time, since rhodamine B (RhB) can quench the fluorescence of this probe, by introducing ferrous ions (Fe 2+ ) and hydrogen peroxide, based on Fenton reaction, the fluorescence signal of this probe can be recovered after the degradation of RhB, so it also can be used to detect Fe 2+ . Importantly, as the first report of UCNP@MOF probes for detecting Fe 3+ and Fe 2+ , respectively, this method exhibits a good selectivity and anti‐interference capability. Finally, it was used to detect Fe 3+ and Fe 2+ in the serum with excellent recoveries.