Particles having a magnetic core and outer glass layer for separating biological material

TLDR: Magnetic glass particles are prepared by forming a mixture of magnetic cores with a sol formed from an alcohol and a metal alkoxide, spray-drying the mixture to coat the core with a layer of gelled sol, and heating the coated cores to obtain the magnetic glass particles.

Abstract: Magnetic glass particles are prepared containing a magnetic core coated with a glass layer having a substantially pore-free glass surface. The particles are used for separating biological material such as nucleic acids. A preferred process of preparing the particles is by forming a mixture of magnetic cores with a sol formed from an alcohol and a metal alkoxide, spray-drying the mixture to coat the cores with a layer of gelled sol, and heating the coated cores to obtain the magnetic glass particles. Preferably, the particles have an average particle size of less than 100 μm and any pores of the glass surface have a diameter of less than 10 nm. The magnetic core may be a composite material containing a mica core and magnetite particles immobilized on the mica core, and the glass layer may contain boron oxide. Magnetic core materials include magnetite (Fe3O4) and Fe2O3. In using the magnetic glass particles to separate a biological material, the particles are contacted with a fluid containing the biological material such that the biological material binds to the glass surface, and the bound biological material is separated from the fluid such as by using a magnetic field. Before applying a magnetic field, the magnetic particles may sediment when contacted with the biological material.