Controllable Preparation And Biological Activity Of Heterogeneous Magnetic Nanoparticles

In the past decade, the synthesis of superparamagnetic nanoparticles had beenwidely used not only based on scientific interest, but also have many technical aspectsof the application, including: MRI contrast enhancement, tissue repair, immune,biological detoxification, hyperthermia, drug delivery and cell separation. Biologicalrequirements for all applications of nanoparticles have high magnetization, and anarrower particle size of less than100nm particle size distribution. These applicationsalso require magnetic nanoparticles with specific surface groups, biocompatible,non-toxic, provide specific targeted drug delivery platform. Such magneticnanoparticles can bind to, proteins, enzymes, antibodies or nucleic acids to locate theorgan, tissue or tumor site by the action of an external magnetic field.In this thesis, a systematic study of the contents of two steps: preparation andcharacterization of magnetic nanoparticles and composites; magnetic-fluorescent andother multi-modal biological probes used in biomedical imaging biological targeting aDetails are as follows: Dumbbell-like Fe3O4-Au magnetic composite nanoparticleswere prepared using decomposition of Fe(CO)5to grow on the surface of the Auseeds in1-octadecene solvent pyrolysis, the diameter of Au nanoparticles in2-8nm,Fe3O4diameter of the nanoparticles is about4-20nm. Retaining in the compositeparticles of surface Au nanoparticles have ion absorption properties of Fe3O4magneticnanoparticles to form a dumbbell-like structure due to the growth of Fe3O4nanoparticles is formed on the Au seeds and the growth can be affected by the solvent.Dumbbell-like Fe3O4-Au nanoparticles coated with the amphiphilic, biocompatiblepolymerized PMAL were prepared.In FeC136H2O and FeC124H2O as the starting material, the smaller particle size and better dispersion were prepared by coprecitation. Fe3O4magneticnanoparticles were coated by ammonium citrate and polyethylene glycol (PEG), thewater-solubility of coated nanoparticles had improved; the dispersivity had increasedbecause that the eledtrostatic repulsive force between particles incressed after modified.On this basis, using Fe3O4nanoparticles were producted by hydrothermal disperse inglucose. Usually, an carbon coating on the surface of magnetic nanoparticles providesbetter protection against external environment, and gives magnetic nanoparticles withnovel properties such as biocompatible, conductivity. DLS、TEM、FTIR、UV、VSMwere used to investigate the characterization of magnetic nanoparticles.The water-soluble quantum dots were coated on the surface of Dumbbell-likeFe3O4-Au magnetic nanoparticles by the method of electrostatic to reachmulti-modality imaging purposes. Fe3O4nanoparticles can be MRI imaging, Aunanoparticles can be near-infrared imaging, load quantum dot can be fluorescenceimaging. By EDC/NHS cross-linking nucleic acid with amino groups to identifyingthe cells specificity. And the fluorescent and magnetic properties of the nanoparticleswere characterized by TEM、Confocal. The results show that multi-modal magneticfluorescent probes were prepared with high transfection efficiency, multi-dimensionalimaging, greatly increasing the effectiveness of detection. And achieve a specific effecton the recongnition to tumor cells.