Crosslinked compounds and methods of making and using thereof

1. A method for locally administering an in-situ crosslinkable or crosslinked gel to a subject in need thereof, the method comprising:

(a) reconstituting a first composition comprising a thiol-functionalized hyaluronic acid (HA) in a buffer to form a first reconstituted composition; reconstituting a second composition comprising a thiolated collagen or a thiolated gelatin of formula (I)

where Y is a residue of collagen or gelatin, in a buffer to form a second reconstituted composition, mixing the first and second reconstituted compositions with a homobifunctional crosslinker comprising two electron-deficient vinyl groups under conditions effective to promote crosslinking of the resulting mixture, and

(b) applying or injecting the mixture from (a) onto or into a body site of the subject, wherein crosslinking of the mixture either prior to or after applying or injecting on or within the body site is effective to convert the mixture into a crosslinked hydrogel.

2. The method of claim 1 , wherein the thiol-functionalized HA is HA functionalized with acyl-hydrazide moieties having terminal thiol groups.

3. The method of claim 1 , wherein the thiol-functionalities on the thiol-functionalized HA are selected from —NH—NH—C(O)—(CH 2 ) 2 SH and —NH—N H—C(O)—(CH 2 ) 3 —SH.

4. The method of claim 3 , wherein the first composition comprising a thiol-functionalized HA prior to reconstituting is in dried form.

5. The method of claim 3 , wherein said first or second composition from step (a) further comprises a pharmaceutically acceptable excipient.

6. The method of claim 3 , wherein said applying or injecting is carried out by spraying, squirting, brushing, painting, or coating.

7. The method of claim 3 , wherein said applying or injecting is carried out by syringe with or without a needle or by cannula.

8. The method of claim 3 , wherein the body site is a nasal cavity.

9. The method of claim 3 , wherein the body site is a joint.

10. The method of claim 9 , for conducting viscosupplementation.

11. The method of claim 3 , for treating a bone or cartilage defect in said subject, wherein step (b) comprises injecting the mixture into the bone defect or into the cartilage defect in a joint.

12. The method of claim 3 , for reducing post-surgical adhesions, wherein step (b) comprises applying or injecting the mixture onto or into a tissue site.

13. The method of claim 12 , wherein said surgical tissue site is in the nasal cavity.

14. The method of claim 3 , for use in wound healing in said subject, wherein step (b) comprises applying or injecting the mixture onto or into a wound bed.

15. The method of claim 3 , wherein said hydrogel is shape-retaining.

16. The method of claim 1 , wherein the thiol-functionalized HA in step (a) possesses a molecular weight ranging from 10,000 to 1,000,000 daltons.

17. The method of claim 1 , wherein the second composition comprises a thiolated gelatin of formula (I).

18. The method of claim 1 , wherein formula (I) is

19. The method of claim 1 , wherein formula (I) is

20. The method of claim 1 , wherein the buffer is phosphate buffered saline.

21. The method of claim 1 , wherein said homobifunctional crosslinker is selected from the group consisting of a diacrylate, a dimethacrylate, a diacrylamide, and a dimethylacrylamide.

22. The method of claim 21 , wherein the crosslinker is selected from the group consisting of a polyether-diacrylate, a polyether-dimethacrylate, a polyether-diacrylamide, and a polyether-dimethylacrylamide.

23. The method of claim 22 , wherein the crosslinker is selected from the group consisting of polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polyethylene glycol diacrylamide, and polyethylene glycol diamethylacrylamide.

24. The method of claim 1 , wherein the thiol-functionalized HA is present in excess relative to the crosslinker based upon moles thiol to moles electron-deficient vinyl groups.

25. The method of claim 24 , wherein gellation occurs within an hour of the applying or injecting step.

26. The method of claim 1 , further comprising adding to the mixing step a biologically active compound, wherein cross-linking of the mixture is effective to form a hydrogel comprising the biologically active compound, and from which the biologically active compound is released in a sustained fashion.

27. The method of claim 26 , wherein the biologically active compound is a steroidal anti-inflammatory compound.

28. The method of claim 27 , for reducing post-surgical adhesions, wherein step (b) comprises applying or injecting the mixture onto or into a tissue site.

29. The method of claim 28 , wherein said tissue site is in the nasal cavity.

30. The method of claim 26 , wherein the thiol-functionalized HA in step (a) possesses a molecular weight ranging from 10,000 to 1,000,000 daltons.

31. The method of claim 26 , wherein the thiol-functionalized HA is HA functionalized with acyl-hydrazide moieties having terminal thiol groups.

32. The method of claim 26 , wherein the first composition prior to reconstituting is in dried form.

33. The method of claim 26 , wherein said first or second composition further comprises a pharmaceutically acceptable excipient.

34. The method of claim 26 , wherein said applying or injecting is carried out by spraying, squirting, brushing, painting, or coating.

35. The method of claim 26 , wherein said applying or injecting is carried out by syringe with or without a needle or by cannula.

36. The method of claim 26 , wherein the body site is a nasal cavity.

37. The method of claim 26 , wherein the body site is a joint.

38. The method of claim 26 , for treating a bone or cartilage defect in said subject, wherein step (b) comprises injecting the mixture into the bone defect or into the cartilage defect in a joint.

39. The method of claim 26 , wherein said hydrogel is shape-retaining.