| Magnetic nanoparticles have been widely used in many fields because of thesmall size effect, quantum effect and unique superparamagnetism. Especially, ironoxide nanoparticles are often favored for biomedical applications, such as proteinseparation, targeted drug delivery, cell separation, etc. Ferric oxide as magneticmicrospheres has gradually drawn more and more attention due to the goodbiocompatibility of ferric oxide for ideal magnetic microsphere, rapid magneticresponse and surface functional groups. In this paper, we studied the synthesis ofFe3O4nanoparticles, SiO2coating and functional modifications, fixed interval arm,protein ligands and the target protein separation. The main achievements are asfollows:Fe3O4nanoparticles were synthesized through the thermal decomposition ofiron-oleate. A fine adjustment of the synthetic conditions had been carried out toobtain magnetite nanoparticles, such as solvent, precursor processed temperatures,oleic acid, reaction temperatures and time, etc. XRD, TEM and VSM were employedfor modifying the characterizations of the nanoparticles. As a result, the sizes ofmonodisperse nanoparticles within6~28nm in diameter were obtained. The XRD andVSM data indicated that iron oxide nanoparticles are the spinal structure andsuperparamagnetic respectively.Fe3O4@SiO2core-shell nanoparticles were obtained by the reverse microemulsion method. The characterizations of the Fe3O4@SiO2nanoparticles had beenmodified by XRD, TEM and VSM. The results showed that the shell thickness ofFe3O4@SiO2nanoparticles are at range from20nm to30nm, the crystallinity Fe3O4nanoparticles has not been changed with the amorphous silica coated, and though thesaturation magnetization strength is weakened, it can meet the requirements ofsubsequent experiments for further functionalization. Fe3O4@SiO2nanoparticles weredecorated with3-Aminopropyl triethoxysilane, and studied on the effect of silanecoupling agent, reaction time and temperatures on the surface modification ofFe3O4@SiO2composite microspheres. Then it was characterized by nanosize Zetapotential for surface charge, we found the surface charge of the Fe3O4@SiO2composite microspheres are positive. Meanwhile, the corrosion resistances of Fe3O4nanoparticles and Fe3O4@SiO2particles were figured out that Fe3O4nanoparticles areseriously corroded by the change of quality of the two kinds of particles, but there isno obvious change for the Fe3O4@SiO2particles, which means the corrosionresistance of the Fe3O4has been enhenced by SiO2coating.The aminated Fe3O4@SiO2nanoparticles were modified by glutaraldehyde forgrafting the covalently immobilized Protein A through controlling the volume of glutaraldehyde, reaction time and temperatures. Then the negative surface charge wasdetected by nanosize Zeta potential, electricity. UV spectrophotometer resultsconfirmed that the incubation time, temperature and initial concentration of proteinwill impact on the quality of protein ligands.The protein ligands and the specificity of the IgG were combined for proteinseparation. UV spectrophotometer results figured out the quality of IgG is decided bythe incubation time and initial concentration of protein. We also found that thediameter of Fe3O4@SiO2is narrow particle size distribution with perfectsphere-shaped morphologies. These microspheres with high separable and reusableefficient may have great potential application in the field of separation. Adsorptioncapacities of microspheres of IgG are ranging from50mg/g to200mg/g. |
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