| Poly(styrene-acrylic acid) is one of important polymers.In recent years, poly(styrene-acrylic acid) microspheres with carboxyl have aroused widespread concerns from scientific research personnel due to increased market demands and strict requirements to performance of microspheres. Copolymerization of styrene with acrylic acid can result in alternative copolymer, easily used for fuctional design. It will extend the application fields of polymer materials.The former studies on the copolymer of styrene and acrylic acid mainly focused on the copolymerization methods and mechanism, and few studies on the synthesis and fuction design of copolymer microspheres were reported. In this paper, synthesis, characterization and biomedical application of magnetite/copolymer composite microspheres with the magnetic responsibility and designed fuction surface were emphasized.Magnetic fluid was prepared by chemical co-precipitation of Fe2+/Fe3+ in an alkali aqueous solution of polyethylene glycol (PEG), with stirring and nitrogen purging. The resulting magnetic colloid particles (MPS) were encapsulated by PEG with an average particle size of 10 nm. They were then dialyzed for one week and used as the polymerization seeds. Morphorlogy and size of the particles were determined by TEM, Structure and composition were characterized by IR. The effects of Fe2+/Fe3+ ratio, stirring speed, temperature, pH and dropping speed on the formation of the magnetic fluids were investigated. Average 10nm magnetic microspheres of high purity and strong magnetism were prepared The stability and magnetic responsibility of magnetic fluid was the highst with 2:3 of Fe2+/Fe3+, excessive 25% and 15ml/min of NaOH, temperature 60℃and stirring speed 1500r/min.Fe3O4/Poly(styrene-acrylic acid)composite microspheres were synthesized by dispersion copolymerization of styrene and acrylic acid with magnetite colloids as polymerization seeds, BPO as initiator ,divinyl benzene as coupling agent in the dispersion medium of alcohol /water. The magnetic particles were encapsulated by polyethylene glycol, which improved the affinity between the magnetite particles and the monomers, thus showing that the size of the microspheres, the amount of the surface carboxyls, and the magnetic content in the composite are highly dependent on magnetic particles, comonomer ratio, and dispersion medium used in the polymerization. The composite microspheres, with a diameter of 3~37μm and 0.1~0.5 mmol surface carboxyl groups/g microsphere, were obtained. Neutravidin was conjugated with the reactive surface carboxyl groups on the surface of the microspheres by covalent binding to obtain a magnetic composite avidin-based microsphere. The microspheres, loading 39~68mg/g of neutravidin, not only retain bioactivities of avidin but also provide magnetic susceptibility. They can be used as a carrier for magnetic orientation and immunomagnetic beads, which were prepared by immobilizing antibody onto the surface of magnetic composite avidin-based microspheres through the special interaction of avidin-biotin. The immunomanetic microspheres, labeled with the antibody of mammary cancer cells, were used for the negative selection procedure of magnetic activated cell sorting and their purity and the ratio of viability and recovery were assessed. The removal rate of cancer cell and the recovery rate of microspheres can be up to 70% and 98%, repectively. These microspheres will get better application prospects in the biomedical fields.
|
PDF Full Text Request