Magnetic particles
A magnetic particle comprises a polysaccharide matrix and a plurality of magnetic crystals dispersed in the matrix. A method for making magnetic particles comprises combining a basic solution with a metal ion solution and allowing the metal ions to oxidize to form magnetic crystals, and combining the magnetic crystals with a polysaccharide solution to form the magnetic particles.
1. A magnetic particle comprising:
an aggregate of polysaccharide coated magnetic crystals, each polysaccharide coated magnetic crystal comprising a magnetic crystal and a polysaccharide coating the magnetic crystal,
wherein the magnetic crystals comprise 75 to 83 wt % of the particle.
2. The magnetic particle of claim 1 , wherein the magnetic particle has a particle diameter of between 0.5 and 10 microns.
3. The magnetic particle of claim 1 , wherein the magnetic particle has a diameter of between 0.9 microns and 2.5 microns.
4. The magnetic particle of claim 1 , wherein the magnetic crystals comprise a transition metal oxide.
5. The magnetic particle of claim 4 , wherein the transition metal oxide is an iron oxide.
6. The magnetic particle of claim 4 , wherein the transition metal oxide comprises at least one of Fe 2 O 3 and Fe 3 O 4 .
7. The magnetic particle of claim 1 , wherein the magnetic crystals have a crystal diameter of between 5 nm and 50 nm.
8. The magnetic particle of claim 1 , wherein the polysaccharide is dextran.
9. A magnetic particle comprising an aggregate of polysaccharide coated magnetic crystals, each polysaccharide coated magnetic crystal comprising a magnetic crystal and a polysaccharide coating the magnetic crystal, the magnetic particle prepared according to a method comprising
a. combining a basic solution with a metal ion solution and allowing the metal ions to oxidize to form the magnetic crystals;
b. combining the magnetic crystals with a solution of the polysaccharide and allowing the magnetic particles to form, wherein the magnetic crystals comprise 75 to 83 wt % of the particle.
10. A method for separating a first population of cells from a second population of cells suspended in fluid the method comprising:
a. linking a plurality of magnetic particles according to claim 1 to said first population of cells;
b. placing said first and second population of cells in a magnetic field; and
c. recovering one of said first or second populations of cells.
11. The method of claim 10 , wherein said magnetic particles are linked to said first population of cells using tetrameric antibody complexes.
12. The method of claim 11 , further comprising:
d. analyzing said first population of cells by FACs, wherein a shift in a side scatter signal of the first population of cells when bound to the magnetic particles is less than 100%.