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The Surface Functionalization Of Magnetic Nanoparticles And Their Application In Protein Immobilization

Posted on:2015-04-24Degree:MasterType:Thesis
Country:ChinaCandidate:Z Y HuFull Text:PDF
GTID:2181330467464663Subject:Drug analysis
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This paper focused on the synthesis, functionalization and the applications of Fe3O4magnetic nanoparticles(i.e. MNPs) in immobilization and separation of protein.Aqueous magnetite nanoparticles were synthesized by coprecipitation method. Magnetite nanoparticles had superparamagnetism with mean diameter of15nm, and the shape of nanoparticles was spherical. Fe3O4MNPs were not very stable under ambient conditions and tended to agglomerating. Based on the rich hydroxyl groups, the surfaces of Fe3O4MNPs were modified with sodium citrate. With rich carboxyl on the surface, Fe3O4-CA MNPs had good dispersion stability in water.Fe3O4@(PS-co-PAA) magnetic polymer microspheres was synthesized by dispersion polymerization method. The magnetic content was17%, through the magnetic filter, Fe3O4@(PS-co-PAA) magnetic polymer microspheres with excellent magnetic responsiveness could be obtained. But the water dispersion stability of the prepared magnetic microspheres was bad, which limited their further application. By using the carbodiimide method, Fe3O4-CA-PEI magnetic particles were synthesized and the preparation conditions were optimized.To characterize the dispersion stability and magnetic responsiveness of magnetic particles in aqueous solution, the concept of modulus of ultraviolet absorbancy degree was introduced. Several factors of were investigated, including the amount of Fe3O4-CA MPs and PEI usage, the molecular weight of PEI, the usage of sealing reagent and so on. Results of experiments showed that adding active Fe3O4-CA MPs partially by two times under shaking and using sealing reagent could obviously improve particle size distribution of Fe3O4-CA-PEI magnetic particles.The size of Fe3O4-CA-PEI magnetic particle decreased with the decrease of the molecular weight of PEI. When compared with a certain kind of medical magnetic particles, Fe3O4-CA-PEI (PEI Mw=1800) magnetic particle had better dispersion stability and magnetic responsiveness.Transmission electron microscopy (TEM) showed that the size of Fe3O4-CA-PEI magnetic particles ranged from tens of nanometers to hundreds of nanometers, as well as the medical magnetic particles, and the prepared magnetic particles were in different shapes. Thermogravimetric analysis (TGA) showed that Fe3O4content of Fe3O4-CA-PEI magnetic particles as high as91.87%.Fe3O4-CA-PEI-PAA-NHS magnetic particles were used as fixed carrier, bovine serum albumin (BSA) as the model protein, the fixed action of Fe3O4-CA-PEI-PAA-NHS for BSA was examined. The result showed that the best fixed time was60min, and the maximum capacity of BSA was1908mg/g. On this basis, antibodies were fixed on magnetic particles successfully and the prepared magnetic particles were expected to be used for immunoassay.
Keywords/Search Tags:Magnetic Nanoparticles, Surface Functionalization, Polyethylene Imine, Protein Immobilization
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