Preparation Of Magnetic Polymer Microspheres And Study On Adsorption And Application Of Bioactive Substance

Magnetic microspheres means magnetic macromolecule microspheres with magnetic metal (for example: Fe, Co, Ni) or metal oxide inside. They present the characters of both magnet and macromolecule, which can combine various active groups on their surface to combine the enzyme, cell, or antibody, and such bioactive substances. These properties make the microspheres promising in applications in the field of environmental engineering and biotechnology.To obtain quick and convenient separation, magnetic microspheres should possess high magnetic responsiveness, uniform particle size, and abundant surface active groups. The research of this work focused on the preparation, characterization and primary application of magnetic microspheres: different types of magnetic microspheres are prepared by suspension cross-linking polymerization and improved micro-emulsion polymerization, characterized by scan electron microscope, X-ray diffractometer, Vibrating Samples Magnetometer, FT-IR, linked with bio-active substance, and applied preliminary. The results showed as follows:The Fe₃O₄ magnetic particles were prepared by chemical co-precipitation process. Effect of Fe2++Fe3+ concentration, precipitator concentration, ratio of precipitator and Fe2++Fe3+, and reaction temperature were researched. The prepared Fe₃O₄ magnetic particles had uniform size, complete crystal structure and strong magnetic responsiveness, whose particle size was about 20nm, specific saturation magnetization was 54.95emu/g, coercivity was 7.53Oe.Chitosan magnetic microspheres were prepared by suspension cross-linking polymerization with chitosan as monomer, and glutaraldehyde as cross-linking agent. Types and dosage of cross-linking agent, pH of reaction system, mass ratio of chitosan and Fe₃O₄ magnetic particles, and stirring speed were optimized. The prepared chitosan magnetic microspheres were spherical, biocompatible, whose particle size was 30⁵0μm. Case study of cell, yeast cells were immobilized into chitosan magnetic microspheres by swelling-adsorption method to research binding capacity of chitosan magnetic microspheres and cells. And through prepared magnetic immobilized yeast cells applied in alcohol fermentation, fermentation effect and recycle-ability of that were researched by detecting alcoholicity ferment liquor.PSt magnetic microspheres were prepared by improved micro-emulsion polymerization with St as monomer, BPO as initiator, SDS as emulsifier, alcohol/water as dispersion medium. The effects of ultrasonic dispersion, heating method and dripping method to polymerization were investigated. Some process parameters such as dosage of emulsifier, dosage of Fe₃O₄ particles, dosage of initiator and stirring speed were optimized. Prepared PSt magnetic microspheres had uniform size and strong magnetic responsiveness, whose particle size was about 20nm, internal crystal structure was complete, specific saturation magnetization was 34.93emu/g, coercivity was 7.28Oe.PSt/AA magnetic microspheres were prepared with AA as functional monomer, and PSt magnetic microspheres as skeletal material. Prepared PSt/AA magnetic microspheres had uniform size and strong magnetic responsiveness, whose particle size was 5-8μm, surface carboxyl content was 0.1031 mmol/g detected by conductometric titration, specific saturation magnetization was 29.26emu/g, coercivity was 9.07Oe. Then, PSt/AA magnetic microspheres were used in linking protein. Adsorption property of PSt/AA magnetic microspheres for bovine serum albumin was researched, effects of adsorption time and ionic strength of solution were investigated, and recycle-ability of that was studied by using appropriate eluent.PSt/AM magnetic microspheres were prepared with AM as functional monomer, and PSt magnetic microspheres as skeletal material. Prepared PSt/AM magnetic microspheres had uniform size and strong magnetic responsiveness, whose particle size was 5-8μm, surface amino content was 0.25 mmol/g detected by conductometric titration, specific saturation magnetization was 29.81emu/g, coercivity was 10.67Oe. Then, immuno-magnetic microspheres were prepared by linking PSt/AM magnetic microspheres with antibody. Convenient and quick method of competitive magnetic affinity immunoassay was established to detect human serum albumin using prepare immuno-magnetic microspheres connecting ELISA. The best working concentration of immuno-magnetic microspheres, detection range and detection limit of this method were determined, the effect of systematic error on detection result was investigated. Method of direct magnetic affinity immunoassay was established to detect Escherichia Coli using prepare immuno-magnetic microspheres. The best working concentration of immuno-magnetic microspheres and enzyme-labeled antibody, detection range and detection limit of this method were determined; the effect of ionic strength on this method was investigated.