Roche Diagnostics Gmbh

Michael Riedling

Helmut Schmidt

Herbert Harttig

Martin Mennig

Thomas Walter

Christoph Lesniak

Jörg Kleiber

Kurt Weindel

Albert Geiger

J&ouml;rg Kleiber

Christop Lesniak

Martin Menning

Helmut K Schmidt

This invention relates to magnetic particles having a glass surface which are substantially spherical. This invention also relates to methods for making them, as well as to suspensions thereof and their uses for the purification of DNA or RNA in particular in automated processes.

Magnetic glass particles, method for their preparation and uses thereof

Magnetic particles are prepared containing a magnetic core coated with a glass layer having a substantially pore-free glass surface or having pores with a diameter of less than 10 nm. 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 &#x3bc;m. 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 (FeO) and FeO.

Method for separating biological material from a fluid using magnetic particles

Preparations of particles having a glass surface, wherein more than 75% by weight of these particles have a particle size between 0.5 &#x3bc;m and 15 &#x3bc;m and a glass surface which contains between 2 and 6 mole % zinc oxide, have proven to be particularly advantageous in processes for the purification of nucleic acids. This in particular results in an increased nucleic acid yield.

Magnetic particles for purifying nucleic acids

Magnetic particles are prepared containing a magnetic core coated with a glass layer having a substantially pore-free class surface or having pores with a diameter offices than 10 nm. 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 &#x3bc;m. 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 (FeO) and FeO.

Magnetic pigment

Preparations of particles having a glass surface, wherein more than 75% by weight of these particles have a particle size between 0.5 &mgr;m and 15 &mgr;m and a glass surface which contains between 2 and 6 mole % zinc oxide, have proven to be particularly advantageous in processes for the purification of nucleic acids. This in particular results in an increased nucleic acid yield.

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 &mgr;m 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 (Fe,O,) and Fe,O,. 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.

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Saarbrücken, Germany

Michael Riedling