Methods, compositions and devices employing alginic acid hydrogels for highly specific capture and release of biological materials

1. A hydrogel composition comprising:

a plurality of alginic acid molecules;

divalent cations crosslinking the alginic acid molecules;

a plurality of branched polyethylene glycol molecules comprising a plurality of attachment points; and

one or more binding agents,

wherein the alginic acid molecules are conjugated to the branched polyethylene glycol molecules by a first of the attachment points, and the one or more binding agents are conjugated to the branched polyethylene glycol molecules by a second of the attachment points, and wherein the hydrogel composition dissolves in the presence of a chelator.

2. The composition of claim 1 , wherein the branched polyethylene glycol molecules are four-arm molecules.

3. The composition of claim 1 , wherein the one or more binding agents is an antibody, antibody fragment, peptidomimetic compound, peptide, small molecule, or nucleic acid.

4. The composition of claim 3 , wherein the antibody is selected from the group consisting of antibodies against GPR49, LGR5, CD24, FLK1, CD45, CD31, CD34, and sca-1 proteins.

5. A method of capturing and releasing target biological materials from a sample, the method comprising:

(a) providing a microfluidic device comprising one or more chambers for receiving fluids, wherein at least one of the one or more chambers comprises a surface coated with a hydrogel composition, the hydrogel composition comprising:

a plurality of alginic acid molecules; divalent cations crosslinking the alginic acid molecules; branched polyethylene glycol molecules comprising a plurality of attachment points; and one or more binding agents that bind to the target biological materials;

wherein the alginic acid molecules are conjugated to the branched polyethylene glycol molecules by a first of the attachment points, and the one or more binding agents are conjugated to the branched polyethylene glycol molecules by a second of the attachment points, and wherein the hydrogel composition dissolves in the presence of a chelator;

(b) introducing the sample comprising target and non-target biological materials into the one or more chambers under conditions effective to bind the target biological materials to the hydrogel composition; and

(c) releasing the target biological materials using a chelator.

6. The method of claim 5 , further comprising removing the unbound non-target materials from the sample prior to step (c).

7. A method of making a hydrogel composition, the method comprising:

(a) reacting branched polyethylene glycol molecules comprising a plurality of attachment points with one or more binding agents in a buffer; and

(b) reacting the branched polyethylene glycol binding agent solution with alginic acid molecules and divalent cations to form a functionalized hydrogel, the functionalized hydrogel comprising branched polyethylene glycol molecules conjugated at least one alginic acid molecule by a first of the attachment points and further conjugated to one or more binding agents by a second of the attachment points, wherein the hydrogel composition dissolves in the presence of a chelator.

8. The method of claim 7 , wherein the polyethylene glycol molecule is a four-arm molecule.

9. The method of claim 7 , wherein the one or more binding agents is an antibody, antibody fragment, peptidomimetic compound, peptide, small molecule, or a nucleic acid.

10. The method of claim 9 , wherein the antibody is selected from the group consisting of antibodies against GPR49, LGR5, CD24, FLK1, CD45, CD31, CD34, and sca-1 proteins.

11. The hydrogel composition of claim 1 , wherein the divalent cations are Ca 2+ cations.

12. The method of claim 5 , wherein the divalent cations are Ca 2+ cations.

13. The method of claim 7 , wherein the divalent cations are Ca 2+ cations.