The Synthesis And Bio-application Of Magnetic Fluorescent Nanocomposites

As a novel nanoparticles, magnetic fluorescent composite nanoparticles not only has excellent magnetic properties, can be rapid response to external magnetic field and magnetic targeting migration; but also has good fluorescence properties, can be used as a fluorescent probe for a variety of biological molecules marking and tracing. The development of multi-functional magnetic fluorescent nanoparticles will replace the application mode of single nanoparticles, which can be used in more complex and more practical biomedical applications, such as the separation and detection of large biological molecules, enrichment and detection of trace DAN, drug delivery and tumor therapy, and so on. In this paper, we focuses on the preparation of high-quality water-soluble magnetic fluorescent nanoparticles and magnetic fluorescent encoded composite microspheres, and applied to a wide range of biological monitoring and analysis, summarized as follows:In the chapter 1, Firstly, we described the extraordinary physical and chemical properties of the iron oxide and the quantum dots and developments in methods for their synthesis and biological application in detail. And then, we focused on the synthesis and applications of new kinds of nanoparticles, magnetic fluorescent composite nanaoparticles. Finally, we provided the significance and contents of this dissertationIn the chapter 2, we studied the synthesis of aqueous magnetic fluorescent composite, and it as a new kind of fluorescent probe was used in the fluoimmunoassay for the detection of chicken virus. In the first section, a simple synthesis method of small size (about 50 nm in diameter), magnetic and fluorescent bi-functional silica composite nanoparticles (CdTe-Fe3O4/SiO2) were developed. And the optical property, magnetic property, size, stability and dispersion characterization of the bi-functional composite nanoparticles were studied. By modifying the surface of CdTe-FeO4/SiO2 with amino and methylphosphonate groups, biologically functionalized and monodisperse CdTe-Fe3O4/SiO2 composite nanoparticles can be obtained. In the second section, based on this amino-oriented CdTe-Fe3O4/SiO2, we established a new method for microbeads-immunoassay, through specific binding between the antibody-antigen, we succeeded in fluoroimmunoassays detection and separation of Newcastle disease virus (NDV) antigen and Avian virus arthritis virus (AVAV) antigenand. The experiment results illustrated that the fluorescent magnetic composite nanoparticles can be used as fluorescent probes and an excellent separation means for the detection and separation of a various of biological molecules.In the chapter 3, we introduce a new method for detection and purification of trace DNA. In this chapter, the amino functional CdTe-Fe3O4/SiO2 were used to carried out on the enrichment, separation and detection of trace pathogenic DNA, and according to the different melting temperature to complete the separation of target DNA with a base mutation target DNA. This new method not only provides a new method for the detection and purification of the mutation DNA, but also provides a new and effective nanotechnology for enrichment, detection and purification of other trace biological molecules.In the chapter 4, we studied the synthesis of aqueous magnetic fluorescent encoding microspheres, and it as a new kind of fluorescent probe was used in the multi-fluoimmunoassay for the detection and separation of equine virus. In the first section, we introduce the preparation method of magnetic fluorescent encoding microspheres. Magnetic fluorescent encoding microspheres was dual-core-shell structure, which based on the amino-functional CdTe-Fe3O4/SiO2 and coated the two kinds of quantum dots and Fe3O4. In this study, the size, magnetic, fluorescent encoding characteristics, the stability in different pH and salt concentration of the magnetic fluorescent encoding microspheres were also studied in detail. In the section two, we construct a new multi-fluorescent immunoassay method based on the magnetic fluorescent encoding microspheres. By this method, the equine influenza virus (EIV) and equine infectious anemia virus (EIAV) were detected and separated successfully. Combination with competitive immunoassay method, we complete multi-immunoassay detection and separation of label-free EIV and EIAV in the actual sample. Though the experiments, we get that this method is sensitive, convenient and effective and can be used for other antigens detection and separation.In the chapter5, we studied the preparation of a new type of magnetic fluorescent chitosan polymer drug carrier, and application in drug release, targeted drug delivery, cancer cell markers and treatment. Drug targeting transport and tumor labeling and treatment are the important application of magnetic fluorescent composite nanoparticles. In this chapter, we synthesized the CdTe-Fe3O4/SiO2 carboxymethyl chitosan microspheres by conjugation the CdTe-Fe3O4/SiO2 with the carboxymethyl chitosan, then the anti-cancer drug doxorubicin was adsorption on the microspheres; furthmore, through the polymerization of carboxymethyl chitosan and polyacrylic acid to increase the water-soluble of drug carrier, so that it can be applied to the tumor cell therapy applications. In this experiment, this new type of magnetic fluorescent chitosan polymer drug carrier showed excellent fluorescent marker effects and the ability of magnetic targeting transport. When it was used in the co-culture with human prostate cancer cells PC3M, which demonstrated excellent control ability of drug release and treatment of cancer.