Characterization and application of magnetic P (St-co-MAA-co-AM)/SiO₂ composite microspheres

A sol–gel procedure was used to cover the magnetic P (St-co-MAA-co-AM) microspheres with a SiO₂ layer, forming MMS/SiO₂ composite micospheres. The composite spheres were synthesized by a two-step process. First, magnetic P (St-co-MAA-co-MA) microspheres (MMS) were prepared by microemulsion polymerization of styrene (St), methacrylic acid (MAA) and acryamide (AM) in the presence of magnetic fluid. In the next step, MMS/SiO₂ spheres were obtained by addition of tetraethyl orthsilicate (TEOS) to the mixture of MMS, ammonium hydroxide and ethanol. The morphology, structure and properties of the MMS/SiO₂ were characterized and the results indicate that the MMS/SiO₂ spheres are about 2 μm in size with superparamagnetic behavior. The surface of the MMS/SiO₂ spheres was functioned with –COOH successfully. Bioconjugation to IgG was also studied.