| Magnetic fluorescent nanocomposites which integrate the unique magnetic and fluorescent properties of magnetic nanoparticles and fluorescent materials, can be widely used in biomedical and bioengineering fieds, such as multimodal optical/magnetic resonance imaging(MRI), cell labeling and separation, enzyme immobilization, tumor hyperthermia etc. In addition, by choosing different function monomers, magnetic fluorescent microspheres containing surface functional groups (such as hydroxyl, carboxyl, amino, aldehyde and epoxy groups etc.) can be synthesized. What’s more, by choosing N-isopropyl acrylamide (NIPAM) to take part in the copolymerization, multi-responsive magnetic fluorescent thermosensitive microspheres can be prepared. They can be potentially used as carriers in smart drug delivery and controlled release system, thus they are of great significance in the diagnosis and treatment of diseases.This paper describes the design and synthesis of a novel magnetic fluorescent colloidal nanocomposites containing rare earth copolymer. The morphology, size, chemical composition and structure, cytotoxicity, magnetic and fluorescent properties of the synthesized nanocomposites are characterized. Their potential application as multimodal optical/MRI imaging probes and their in vivo distribution in the SD rats are also studied. The details are summarized as follows:(1) Fe3O4nanoparticles are synthesized by traditional co-precipitation methods, followed by modification with oleic acid (OA) to obtain a oil-soluble magnetic fluid, and further modification with sodium undecylenate (NaUA) to obtain bilayer surfactant modified water-soluble magnetic fluid. The products are characterized by FTIR, TEM, TG, XRD, VSM. The results show that the synthesized and modified Fe3O4nanoparticles have cubic phase structure, and are successful modified by OA and NaUA.(2) In the presence of the above water-soluble magnetic fluid, a seed emulsifier-free polymerization technology is used to prepare fluorescent magnetic colloidal nanoparticles (FMCNPs) containing surface epoxy groups, using styrene (St), glycidyl methacrylate (GMA), rare earth complex monomer (Eu(AA)3Phen) as the monomers, and potassium peroxodisulfate (KPS) as the initiator. The morphology, hydrodynamic size and distribution of FMCNPs are characterized by TEM, SEM and PCS. The chemical composition and structure of FMCNPs are characterized by FTIR, XRD and energy dispersive X-ray spectrum (EDX). Their magnetic and fluorescent properties are characterized by VSM and fluorescence spectrophotometer. The results show that Fe3O4nanoparticles are successfully encapsulated by polymers, and the synthesized FMCNPs have uniform core-shell structure, superparamagnetism and good fluorescence properties. The cytotoxicity test of FMCNPs using MTT analysis shows that they have good cytocompatibility. The potential application of FMCNPs in multimodal optical/MRI probes is also studied, using SD rat as the animal model.(3) A similar seed emulsifier-free method is utilized to synthesize multifunctional fluorescent magnetic thermo-responsive nanoparticles (FMTNPs) in the presethe modified magnetic fluid and monomers including St, NIPAM, Eu(AA)3Phen. The synthesized FMTNPs are characterized by TEM, SEM, PCS, TQ FTIR, XRD, VSM and fluorescence spectrophotometer etc. The results show that Fe3O4nanoparticles are successfully encapsulated in FMTNPs, the produced FMTNPs have monodispersed core-shell structure and with cubic phase Fe3O4as the core and thermo-responsive polymer as the shell. FMTNPs have thermosensitivity and superparamagnetism, with a saturation magnetization up to6.45emu/g. The fluorescence spectrum of FMTNPs show the characteristic emission peaks of Eu3+at594nm and619nm, and vivid red luminescence of FMTNPs can be observed by2-photon laser scanning confocal microscope (CLSM). FMTNPs show good cytocompatibility based on the MTT assay. The in vitro and in vivo MRI studies show that FMTNPs can be used as T2contrast agents for rat liver and spleen magnetic resonance imaging. |
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