Magnetic Beads With High Saturation Magnetization

Magnetic beads with the core-shell structure of an iron core encapsulated by titanium oxide and silica shell layers were prepared. The beads, HMM-beads, exhibited soft magnetic properties with high magnetization of 105 Amiddotm
²
/kg and low coercitivity of ~4 kA/m. HMM-beads with a diameter of 3 mum showed DNA isolation performance comparable to that of conventional beads composed of iron oxides. HMM-beads with a diameter of 1 mum coupled with biotinylated anti-EpCAM antibody through Streptavidin linkers also exhibited comparable yields to conventional beads of the same diameter in respect to capturing tumor cells. The response time of the HMM-beads to a magnetic field at magnetic separation was less than one third that of conventional beads in both cases.