Biomagnetic beads, 300 nm in average diameter, were prepared by encapsulating large numbers of ferrite nanoparticles in nonspecific absorption polymer. The coprecipitated ferrite particles, 9.2 nm in diameter, were grown to 12.9 nm by the hydrothermal process (200 °C for 3 h) adding sodium oleate in water. The grown-up ferrite nanoparticles were highly dispersed due to the existence of oleate on the particle surface. The saturation magnetization of ferrite particles increased from 56 to 74 emug with the growth of ferrite particles. These ferrite nanoparticles were encapsulated in a copolymer of polystyrene and poly(glycidyl methacrylate) by an emulsion polymerization method. The polymer coated ferrite beads having sphere shape of 300 nm in average diameter exhibited a saturation magnetization of 55 emug, which was five to six times larger than those of commercialized magnetic beads, in which ferrite (maghemite) nanoparticles are dispersed in polystyrene and Si O2 matrix.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)