Preparation Of Magnetic Silica Composite Microspheres And Its Application In DNA And Protein Separation

Design and synthesis of nanostructured magnetic materials have become a particularly important area of research and are attracting a growing interest because of the potential applications such as bioseparation,diagnostic analysis,immunoassay and so on.Amid these,magnetic silica composite microspheres have attracted more interest in the past decade due to their unique advantages.Based on the background and our group researches on the preparation and functionalization of magnetic polymer microspheres,the monodispersive superparamagnetic microspheres were prepared and applied in separation of biomaromolecules:1.The preparation of monodispersed silica microspheres embedded with superparamagnetic nanoparticles by miniemulsion and the application for plasmid DNA purification have been investigated.Systematical investigations such as the dosages of catalyst and iron oxide nanoparticles,were conducted on the influence of reaction conditions on the morphologies,stabilities and bio-application of the superparamagnetic microspheres.Under the optimized condition,the prepared composite microspheres have the character of monodispersity and quick magnetic response.This characteristic is critical for the application in biomolecular separations.The separation experiment for plasmid DNA showed that the composite microspheres were robust compared with commercialized agent, 2.The magnetic composite microspheres with high magnetic content(62.1wt%) have been prepared by miniemulsion method.Then,through coating the iron oxide-silica mirospheres with mesoporous or amorphous silica shell by sol-gel method,core-shell magnetic silica microspheres are formed and the surface of microsphere became more biocompatible.This is the first time the mesoporous silica shells were coated on the magnetic microsheres embedded with magnetic nanoparticles.The mesoporous and amorphous core-shell magnetic micr0spheres were applied in the separation of plasmid DNA and the results were compared and analyzed.3.High-magnetization silica core/shell microspheres were prepared at first,and then grafted with polyacrylic acid flexible chains and applied in the selective separation of lysozyme.First,we synthesize submicron-size Fe₃O₄ clusters. Second,the core/shell Fe₃O₄@silica microspheres with controllable shell thickness were prepared by sol-gel method.Third,the Fe₃O₄@Silica microspheres were grafted with polyacrylic acid flexible chains to form Fe₃O₄@silica-g-PAA microspheres and greatly improved the adsorptive capacity for iysozyme.With relative high adsorptive capacity,the Fe₃O₄@silica-g-PAA microspheres possess faster magnetic response and shorter equilibrium time compared with previous magnetic adsorbents.This is very significant for the development of scaling-up bioseparation.