Bifunctionalized core-shell structured Fe₃O₄-Zr/Eu MOF achieves highly selective detection and rapid removal of gossypol

Gossypol (Gsp) is a polyphenolic phytotoxin that can cause serious harm to human health and the environment. Therefore, it is necessary to develop a multifunctional sensing material that can efficiently detect and remove Gsp. Herein, a new strategy based on Fe₃O₄ coated with Zr/Eu metal-organic framework (MOF) is proposed for highly selective detection and rapid removal of Gsp. The Zr metal node can efficiently catalyze the formation of boronic esters and C=N bonds between the o-hydroxy and aldehyde groups in Gsp and the amino and boric acid groups on the ligands, thus triggering the fluorescence quenching of Eu³⁺. Owing to the synergistic participation of the o-hydroxy and aldehyde characteristic functional groups, the Fe₃O₄-Zr/Eu MOF exhibits remarkable selectivity and sensitivity, with a LOD (limit of detection) as low as 0.39 nmol/L. Visual detection of Gsp reached 1.93 nmol/L. The accuracy of the material was verified through the classical liquid chromatograph mass spectrometer (LC-MS) analytical method. The maximum Langmuir adsorption amount of Fe₃O₄-Zr/Eu MOF is 157.21 mg/g for Gsp. The detection and removal of Gsp in cottonseed, cottonseed oil and river water as well as the recovery and cyclic adsorption experiments all validated the outstanding application potential of the Fe₃O₄-Zr/Eu MOF in the detection and removal of Gsp within actual samples.