Turn-on fluorescence ferrous ions detection based on MnO2 nanosheets modified upconverion nanoparticles

A turn on upconversion fluorescence probe based on the combination of similar to 32 nm NaYF4: Yb/Tm nanoparticles and MnO2 nanosheets has been established for rapid, sensitive detection of Fe2+ ions levels in aqueous solutions and serum. X-ray diffraction (XRD), transmission electron microscopy (TEM), absorption and emission spectra have been used to characterize the crystal structure, morphology and optical properties of the samples. MnO2 nanosheets on the surface of UCNPs act as a fluorescence quencher, resulting in the quenching of the blue fluorescence (with excitation/emission maximum of 980/476 nm) via fluorescence resonance energy transfer from upconversion nanoparticles to MnO2 nanosheets. With the adding of Fe2+, upconversion fluorescence of the nanocomposites recovers due to the reduction of MnO2 to Mn2+. Because of the low background of the probe offered by upconversion fluorescence, this probe can be used for detecting Fe2+ in aqueous solutions in the range of 0.1-22 mu M with detection limit of 0.113 mu M. The developed method has also been applied to detect 10 mu M Fe2+ ions in serum with recoveries ranging from 97.6 to 105.3% for the five serum samples. Significantly, the probe shows fast response and stable signal, which is beneficial for long-time dynamic sensing. Thus, the proposed strategy holds great potential for disease diagnosis and treatment. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

A novel upconversion fluorescence probe based on the combination of NaYF4: Yb/Tm nanoparticles and MnO2 nanosheets has been developed for rapid and sensitive detection of Fe2+ ions in aqueous solutions and serum. The probe showed fast response, stable signal, and great potential for disease diagnosis and treatment using fluorescence resonance energy transfer and quenching mechanisms.