Preparation and Characterization of the Water-dispersible Magnetic Fluorescent Particles Containing Rare Earth Prepared by Ligand Exchange Reaction

After utilizing coprecipitation method and subsequent modification with oleic acid, oil-based Fe3O4 magnetic nanoparticles with a narrow size distribution were obtained. And a kind of amphiphilic polymer containing rare earth was synthesized by using poly (ethylene glycol) methacrylate, methacryloxy propyl trimethoxyl silane and a complex Eu (AA)(3) Phen as monomers. The oil-based magnetic Fe3O4 nanoparticles were then used as cores, and modified with the amphiphilic polymer via ligand exchange reaction to prepare water-based magnetic fluorescent particles (PMNPs). The morphology, molecular structure, superparamagnetic and fluorescent properties of the particles were characterized by nuclear magnetic resonance spectrometer (NMR), FTIR spectrometer (FEIR), transmission electron microscope (TEM), photon correlation spectroscopy (PCS), X-ray diffractometer (XRD), vibrating sample magnetometer (VSM), fluorescence spectrometer and thermo gravimetric analyzer (TGA). Results showed that the amphiphilic polymer was coated onto the surface of magnetic Fe3O4 nanoparticles effectively and evenly. The magnetic fluorescent particles had a good dispersibility in water phase and can keep a uniform particle size. The average diameter of the particles was just around 45 nm. The particles also had a saturation magnetization of 2. 3 A.m(2)/kg at room temperature, and the rare earth Eu3+ in these PMNPs had obvious characteristic emission spectra at 594 nm and 619 nm with a excitation spectra at 327 nm.