Ratiometric Fluorescence Detection of Piceatannol With Fluorescent Eu-MOF and MnO₂ Nanosheets

Eu-MOF with rhomboid structure and strong fluorescence was successfully synthesized in this work. By combining fluorescent Eu-MOF with peroxidase mimic MnO₂ nanosheets, a novel ratiometric fluorescence sensing method was developed for the sensitive detection of piceatannol (PCT), a naturally occurring stilbene-type polyphenolic compound. The sensing mechanism relies on the strong antioxidant ability of PCT, which reductively decomposes MnO₂ nanosheets into Mn²⁺ and results in the attenuation of the fluorescence intensity of the o-phenylenediamine (OPD) oxidation product and the concomitant recovery of Eu-MOF fluorescence. Consequently, the ratio of fluorescence intensity at two distinct wavelengths is changed with the varying of PCT concentrations, facilitating the sensitive detection of PCT. The results showed that the fluorescence intensity ratio (F₄₃₀/F₅₆₀) exhibited a linear relationship with the concentration of PCT within the range of 0.125-6.25 μM, with an actual detection limit of 0.05 μM. The method was successfully applied to the detection of PCT concentration in the extracellular fluid of RAW 264.7 cells and is expected to provide a promising approach for monitoring the pharmacokinetics of PCT.