| 其他摘要 | Different kinds of multifunctional nanocomposites ultra-small Fe3O4 nanoparticles, magnetic/ polyamidoamine (PAMAM) dendrimers cation nanocomposites and magnetic/ fluorescent nanocomposites were prepared by using the co-precipitation method, sol-gel method, chemical combination and thiol coordination method. Magnetic Fe3O4 nanoparticles with different sizes were prepared by using co-precipitation method by controlling protecting agent and reaction condition. The surface of Fe3O4 nanoparticles were modified by the sol-gel method in which tetraethylorthosilicate as a modifier. Then, Fe3O4@SiO2 nanospheres with different shell thickness were formed. At last, with the modifying of 3-mercatopropyl-trimethoxysilane and 3-aminopropyl-triethoxy silane, Fe3O4@SiO2-NH2 and Fe3O4@SiO2-SH nanospheres were obtained. Fe3O4@SiO2-NH2 nanospheres and PAMAM dendrimers were combined by amidation reaction to form Fe3O4-PAMAM cation nanocomposites. Fe3O4@SiO2-SH nanospheres and CdSe/ZnS quantum dots were assembled by thiol coordination method to form Fe3O4@SiO2-CdSe/ZnS nanocomposites. The phase constitution, particles morphologies, microstructure and the binding energy of the elements of the different kinds of nanocapsules and the structure characteristics of the macro-aggregates have been studied by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), Scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), X-ray energy diffraction spectrum (EDS) in details. The magnetic characteristics, chemical activities, fluorescent and dispersion of the nanocomposites were measured by superconducting quantum interface devices (SQUID), infrared spectroscopy (IR), fluorescence spectroscopy (FL) and atom force microscope (AFM). Possibility of these nanocomposites for application of magnetic resonance imaging (MRI), gene delivery and cell separation was discussed.
Ultra-small Fe3O4 nanoparticles with uniform distribution were prepared by using the co-precipitation method in which the polyvinylpyrrolidone (PVP) serves as a protecting agent. PVP molecules played the role of preventing the aggregation and restricting the size of Fe3O4 nanoparticles. The particles’ size was determined by the dripping rate. When the dripping rate decreased from 1.4 to 0.35 mL/min, the size of the Fe3O4 particles decreased from 6.5 to 1.9 nm. The as-prepared Fe3O4 nanoparticles with diameter from 6.5 to 1.9 nm were homogeneous and well dispersed. In vivo results for magnetic resonance imaging and magnetic targeting showed that the PVP-Fe3O4 particles could be concentrated at the target area and obviously exhibited negative contrast enhancement for lung, liver, spleen, kidney and marrow. The PVP-Fe3O4 particles prepared by the present method have encouraging applications in MRI and magnetic delivery of drug and should be investigated further.
Fe3O4-PAMAM nanocomposites were prepared by using chemical combination by amidation reaction. The magnetic iron-oxide nanoparticles functionalized by amino groups and the PAMAM G5.0 dendrimers terminated by amino groups were combined with the hydrophilic spacer of PEG biscarboxylate by amidation to form nanocomposites. Such nanocomposites with the diameter 180 nm showed excellent dispersion, hydrophilicity and terminated amino groups. These terminated amino groups can further bind gene molecules, therefore, Fe3O4-PAMAM nanocomposites have excellent foreground in magnetic target gene delivery.
The magnetic Fe3O4 particles and CdSe/ZnS quantum dots (QDs) were assembled by sol-gel method and thiol coordination method to form magnetic/fluorescent nanocomposites with a magnetic core of iron oxide Fe3O4 and a shell of CdSe/ZnS quantum dots. The carboxy groups covering outside resulted in the chemical activity and water solubility of the nanocomposites. It was interesting that the nanocomposites with a mean diameter of 25 nm and exhibited well magnetic response, photostability and they could be separated from the solution easily. In addition, the nanocomposites could further react with some ligands with amino groups such as 1-N-[O-b-d-Galactopyranosyl-(1,4)-d-gluconamide]-2-N-methylamine magnetic/ fluorescent nanocomposites to form special target. Such magnetic/ fluorescent nanocomposites can separate hepG cells expressing asialoglycoprotein and benefit for lung cancer diagnosis. |
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