In Situ Assembled Europium Complexes on Alumina Fibers for Highly Selective Fluorescent Sensing of Fe ³⁺

ABSTRACT Iron is an essential trace element, and its excessive Fe 3+ accumulation induces oxidative stress and leads to severe biological toxicity. The development of highly sensitive and selective platforms for Fe 3+ detection is therefore crucial in biomedical and environmental monitoring. Alumina fiber, an important inorganic non‐metallic material, exhibits excellent thermal resistance, oxidation stability, and chemical durability. In this work, a fluorescent alumina fiber (AF@(Eu)BTC) is successfully constructed by In Situ assembling europium complexes onto the surface of alumina fibers. The lanthanide complexes are uniformly distributed as fine particles on the fiber surface. Under UV excitation, AF@(Eu)BTC exhibits a strong red emission at 614 nm, corresponding to the 5 D 0 → 7 F 2 transition of Eu 3+ . The fluorescence is significantly quenched in the presence of Fe 3 + ions. The detection limits (LOD) for Fe 3+ are determined to be 0.060 µM in aqueous solution and 0.085 µM in ethanol solution. This work demonstrates a new strategy for constructing highly sensitive fluorescent platforms for Fe 3+ detection and offers new prospects for the application of functionalized alumina fibers in sensing technologies.