Magnetic particles for use in separations
AssigneeAdvanced Magnetics, Inc.
InventorsRoy A. Whitehead, Mark S. Chagnon, Ernest V. Groman, Lee Josephson
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Abstract
A process is provided for the preparation of magnetic particles to which a wide variety of molecules may be coupled. The magnetic particles can be dispersed in aqueous media without rapid settling and conveniently reclaimed from media with a magnetic field. Preferred particles do not become magnetic after application of a magnetic field and can be redispersed and reused. The magnetic particles are useful in biological systems involving separations.
Claims11
A coupled magnetically-responsive particle comprising a magnetic metal oxide core generally surrounded by a coat of polymeric silane to which molecules of at least one type of bioaffinity adsorbent are covalently coupled, a mass of the uncoupled particles being dispersable in aqueous media to form an aqueous dispersion having (a) a fifty-percent-turbidity-decrease settling time of greater than about 1.5 hours in the absence of a magnetic field, and (b) a ninety-five-percent-turbidity-decrease separation time of less than about 10 minutes in the presence of a magnetic field, the magnetic field being applied to the aqueous dispersion by bringing a vessel containing a volume of the dispersion into contact with a pole face of a permanent magnet, the permanent magnet having a volume which is less than the volume of the aqueous dispersion in the vessel.
A coupled magnetically-responsive particle comprising a superparamagnetic iron oxide core generally surrounded by a coat of polymeric silane to which molecules of at least one type of bioaffinity adsorbent are covalently coupled, the iron oxide core including a group of crystals of iron oxide, the uncoupled particle having a mean diameter as measured by light scattering between about 0.1.mu. and about 1.5.mu. and a surface area as measured by nitrogen gas adsorption of at least about 100 m.sup.2 /gm, a mass of the uncoupled particles being dispersable in aqueous media to form an aqueous dispersion having (a) a fifty-percent-turbidity-decrease settling time of greater than about 1.5 hours in the absence of a magnetic field, and (b) a ninety-five-percent-turbidity-decrease separation time of less than about 10 minutes in the presence of a magnetic field, the magnetic field being applied to the aqueous dispersion by bringing a vessel containing a volume of the dispersion into contact with a pole face of a permanent magnet, the permanent magnet having a volume which is less than the volume of the aqueous dispersion in the vessel.
A coupled magnetically-responsive particle comprising a ferromagnetic metal oxide core generally surrounded by a coat of polymeric silane to which molecules of at least one type of bioaffinity adsorbent are covalently coupled, the metal oxide core including a group of crystals of metal oxide, the uncoupled particle having a mean diameter as measured by light scattering between about 0.1.mu. and about 1.5.mu. and a surface area as measured by nitrogen gas adsorption of at least about 100 m.sup.2 /gm, a mass of the uncoupled particles being dispersable in aqueous media to form an aqueous dispersion having (a) a fifty-percent-turbidity-decrease settling time of greater than about 1.5 hours in the absence of a magnetic field, and (b) a ninety-five-percent-tubidity-decrease separation time of less than about 10 minutes in the presence of a magnetic field, the magnetic field being applied to the aqueous dispersion by bringing a vessel containing a volume of the dispersion into contact with a pole face of a permanent magnet, the permanent magnet having a volume which is less than the volume of the aqueous dispersion in the vessel.
Dependencies are inferred from the claim text.