Highly Sensitive and Selective Fluorescence “Turn-On” Detection of Pb (II) Based on Fe ₃O ₄@Au–FITC Nanocomposite

Abstract

New nanocomposites, Fe ₃O ₄@Au–FITC, were prepared and explored to develop a fluorescent detection of Pb ²⁺. The Fe ₃O ₄@AuNPs–FITC nanocomposites could be etched by Pb ²⁺ in the presence of Na ₂S ₂O ₃, leading to fluorescence recovery of FITC quenched by Fe ₃O ₄@Au nanocomposites. With the increase of Pb ²⁺ concentration, the fluorescence recovery of Fe ₃O ₄@AuNPs–FITC increased gradually. Under optimized conditions, a detection limit of 5.2 nmol/L of Pb ²⁺ with a linear range of 0.02–2.0 µmol/L were obtained. The assay demonstrated negligible response to common metal ions. Recoveries of 98.2–106.4% were obtained when this fluorescent method was applied in detecting Pb ²⁺ spiked in a lake-water sample. The above results demonstrated the high potential of ion-induced nanomaterial etching in developing robust fluorescent assays.