Fluorescence Enhancement Method for Enrofloxacin Extraction by Core–Shell Magnetic Microspheres

Abstract

In this work, we present novel kinds of γ-Fe2O3@SiO2-NH2-CMC/MOF5 and γ-Fe2O3@SiO2-NH2-CMC/IRMOF3 magnetic metal–organic framework (MOF) nanoparticles which possess both magnetic characteristics and fluorescent properties. Here, [Zn4O(bdc)3] (MOF-5, bdc=1,4-benzenedicarboxylate) is a kind of shell. IRMOF3, a known MOF with a cubic topology prepared from Zn(NO3)2⋅4H2O and 2-amino-1,4-benzene dicarboxylic acid, is another kind of shell which is attractive due to its highly porous, crystalline structure and the presence of non-coordinating amino groups on the benzenedicarboxylate (bdc) linker, which are amenable to post-synthetic modification. γ-Fe2O3@SiO2-NH2-CMC magnetic nanoparticles (MNPs) could be prepared by covalent modification of sodium carboxymethyl cellulose (CMC). The structure of γ-Fe2O3 nanoparticles could be determined by X-ray powder diffraction (XRD). X-ray photoelectron spectroscopy (XPS) spectra could be used for the characterisation of γ-Fe2O3@SiO2-NH2, γ-Fe2O3@SiO2-NH2-CMC, γ-Fe2O3@SiO2-NH2-CMC/MOF5, and γ-Fe2O3@SiO2-NH2-CMC/IRMOF3 nanoparticles. Magnetic solid-phase extraction (MSPE) of enrofloxacin (Enr) experiments exhibited that, for γ-Fe2O3@SiO2-NH2-CMC/IRMOF3, the best effects of adsorption could be obtained at pH 4 and 6, while elution conditions of 0.1mol L−1 NaOH and 1% sodium dodecyl sulfate could achieve the best elution effect. The addition of Tb3+ ions could sensitise the fluorescence of Enr. At the same time, via the addition of Tb3+ ions, coordination could occur between nanoparticles and Tb3+ ions, which could be verified by XPS.