Cell processing using magnetic particles

1. A method of processing sperm cells comprising the steps of:

a) forming a stream comprising the sperm cells;

b) determining whether a property of interest is present or absent in the sperm cells in the stream;

c) ablating or photodamaging a subpopulation of the sperm cells based on the presence or absence of the property of interest in the sperm cells;

d) collecting the sperm cells;

e) adding magnetic particles to the collected sperm cells to form a mixture, the magnetic particles having a diameter of 30 to 1000 nm and comprising a chargeable silicon-containing compound, the magnetic particles binding to the ablated or photodamaged subpopulation of sperm cells solely through an electrical charge interaction;

f) applying a magnetic field to the magnetic particle-bound sperm cells; and

g) removing the magnetic particle-bound subpopulation from the mixture.

2. The method of claim 1 , the magnetic particles comprising an outer layer comprising a polysaccharide, an alkylsilane, a polylactic acid, a polycaprolactone, polyhydroxybutyrate-valerate or a polyolefin.

3. The method of claim 2 , the outer layer further comprising a chargeable, or charged, moiety.

4. The method of claim 3 , the chargeable, or charged, moiety comprising a metal, an oxide, a carboxylate, an amine, an amide, a carbamide, a sulfate, a sulfonate, a sulfite, a phosphonate, a phosphate, a halide or a hydroxide.

5. The method of claim 1 , wherein the mixture has a pH of 6.5 to 8.0.

6. The method of claim 1 , wherein the mixture comprises a buffer.

7. The method of claim 1 , wherein the mixture comprises sperm cells at a concentration of 120×10 6 cells/ml to 500×10 6 cells/ml.

8. The method of claim 1 , wherein the magnetic particles are non-toxic to the sperm cells.