Compositions and methods for rapid and reversible biomolecular labeling
This disclosure provides compositions and methods for a low-avidity, high-affinity and high-specificity biomolecular interaction that is rapidly reversible under physiological conditions. The methods comprise linking biological targets (such as molecules, proteins, DNA, cells, etc.) with polymers and anti-polymer ligands and a way to reverse their binding using physiologically compatible polymeric compounds. The methods also comprise a way to combine different polymer/anti-polymer systems for orthogonal labeling. The compositions comprise labels including particles (fluorescent, magnetic, dense, etc.) conjugated to polymers or labels conjugated to anti-polymer antibodies. The compositions also comprise biomolecules (proteins, antibodies, DNA, etc.) conjugated to the polymers. These methods and compositions represent a major improvement to the state-of-the-art. They are particularly useful for separation and isolation of biological targets using particles, but have important application to other fields including fluorescent imaging.
1. A method of separating target cells from a label in a sample comprising:
1) Binding the target cells to the label through a linking system comprising (i) an antibody that binds to the target cells, (ii) an antibody that binds to a first polymer, and (iii) a label either conjugated with the first polymer or with the antibody that binds to the first polymer, the first polymer having a first molecular weight;
2) Separating the target cells bound to the label from the sample to enrich a first population of the target cells;
3) contacting the enriched cells of step 2) with a second polymer, the second polymer having a second molecular weight and specifically reversing the interaction between the antibody that binds to the first polymer and the first polymer, wherein a ratio of the first molecular weight and the second molecular weight is 10:1 or less; and
4) separating label from the target cells to obtain a second population of the target cells with increased cell purity compared to the first population of the target cells, wherein a percentage of the target cells in the second population is higher than a percentage of the target cells in the first population.
2. The method according to claim 1 wherein the first and second polymer have similar affinity for the ligand.
3. The method according to claim 1 wherein the first and second polymer are independently selected from PEG, PEG derivatives, poly(carboxybetaine), dextran, starch, heparin, chitin, cellulose, peptides and nucleic acids.
4. The method according to claim 1 wherein the label is selected from solid supports, fluorescent proteins and dyes, antibodies, enzymes, functional proteins, peptides or growth factors and radioactive or elemental tags.
5. The method according to claim 1 wherein the first polymer and second polymers are independently selected from PEG and PEG derivatives.
6. The method according to claim 1 wherein the label is a solid support.
7. The method according to claim 6 wherein the solid support comprises particles.
8. A method of separating target cells from a label in a sample, comprising:
1) Binding the target cells to a label through a linking system comprising (i) an antibody that binds to the target cells, (ii) an antibody that binds to a first polymer, and (iii) a label either conjugated with a first polymer or with the antibody that binds to the first polymer;
2) Separating the target cells bound to the label from the sample to enrich a first population of the target cells;
3) contacting the enriched cells of step 2) with a second polymer, the second polymer specifically reversing the interaction between the antibody that binds to the first polymer and the first polymer; and
4) separating label from the target cells to obtain a second population of recapturable target cells with increased cell purity compared to the first population of the target cells, wherein a percentage of the target cells in the second population is higher than a percentage of the target cells in the first population.
9. The method according to claim 8 wherein the first and second polymer have similar affinity for the ligand.
10. The method according to claim 8 wherein the first and second polymer are independently selected from PEG, PEG derivatives, poly(carboxybetaine), dextran, starch, heparin, chitin, cellulose, peptides and nucleic acids.
11. The method according to claim 8 wherein the label is selected from solid supports, fluorescent proteins and dyes, antibodies, enzymes, functional proteins, peptides or growth factors and radioactive or elemental tags.
12. The method according to claim 8 wherein the first polymer and second polymers are independently selected from PEG and PEG derivatives.
13. The method according to claim 8 wherein the label is a solid support.
14. The method according to claim 13 wherein the solid support comprises particles.
15. The method according to claim 1 wherein the concentration of the second polymer is between 0.0001 to 10% w/v.
16. The method according to claim 15 wherein the concentration of the second polymer is between 0.0001 5% w/v.
17. The method according to claim 1 wherein the range of the ratio of the first molecular weight and the second molecular weight is between 1:1 to 8:1.
18. The method according to claim 8 wherein the range of the ratio of a molecular weight of the first polymer and a molecular weight of the second polymer is between 1:1 to 8:1.
19. A method of separating target cells from a label in a sample comprising:
1) Binding the target cells to the label through a linking system comprising (i) an antibody that binds to the target cells, (ii) an antibody that binds to a first polymer, and (iii) a label either conjugated with the first polymer or with the antibody that binds to the first polymer;
2) Separating the target cells bound to the label from the sample to enrich a first population of the target cells;
3) contacting the enriched cells of step 2) with a second polymer, the second polymer specifically reversing the interaction between the antibody that binds to the first polymer and the first polymer; and
4) separating label from the target cells to obtain a second population of the target cells with increased cell purity compared to the first population of the target cells, wherein a percentage of the target cells in the second population is higher than a percentage of the target cells in the first population.
20. The method according to claim 16 wherein the concentration of the second polymer is between 0.001 to 5% w/v.