Stimulus responsive polymers for the purification of biomolecules

1. A method of separating a target molecule from one or more impurities in a sample, where the method comprises the steps of:

(a) providing a sample comprising a target molecule and one or more impurities;

(b) contacting the sample with a soluble stimulus responsive polymer selected from the group consisting of benzyl modified polyallylamine; diphenyl modified polyallylamine; dichlorobenzyl modified polyallylamine; chlorobenzyl modified polyallylamine; hexanoic acid and tert-butyl modified polyallylamine; phenylbenzyl modified polyallylamine; benzyl modified polyethyleneimine; and benzyl modified polyvinylamine, wherein the stimulus responsive polymer is capable of binding and precipitating one or more impurities following the addition of a multivalent ion stimulus; and

(c) adding a multivalent ion stimulus selected form phosphate or citrate to the sample to precipitate complex of polymer and one or more impurities out of the sample;

thereby to separate the target molecule from one or more impurities.

2. The method of claim 1 , wherein the target molecule is a recombinant protein.

3. The method of claim 1 , wherein the target molecule is an antibody.

4. The method of claim 3 , wherein the antibody is a monoclonal antibody.

5. The method of claim 1 , wherein the one or more impurities is selected from the group consisting of host cell protein, DNA, RNA, viruses, antibody aggregates and cell culture additives.

6. The method of claim 1 , wherein the sample comprises a feedstock.

7. The method of claim 1 , wherein the sample comprises cell culture media into which the target molecule is secreted.

8. The method of claim 7 , wherein the cell culture media is a CHO cell culture media.

9. The method of claim 7 , wherein the target molecule is a monoclonal antibody.

10. The method of claim 1 , further comprising one or more chromatography steps.

11. The method of claim 1 , further comprising one or more filtration steps.

12. The method of claim 1 , further comprising the step of removing a residual amount of polymer after step (c), wherein the step comprises the use of a membrane or resin modified with a multivalent ion.

13. The method of claim 12 , wherein the multivalent ion is phosphate.