Carbohydrate crosslinker
The invention relates to a hydrogel product comprising glycosaminoglycan molecules as the swellable polymer, wherein the glycosaminoglycan molecules are covalently crosslinked via crosslinks comprising a spacer group selected from the group consisting of di-, tri-, tetra-, and oligosaccharides.
1. A process of preparing a hydrogel product comprising crosslinked hyaluronic acid (HA) molecules, the process comprising:
(a) activating carboxyl groups on the HA molecules with a coupling agent to form activated HA molecules;
(b) crosslinking the activated HA molecules via their activated carboxyl groups using diaminotrehalose to obtain crosslinked HA molecules; and
(c) hydrolyzing ester bonds in the crosslinked HA molecules via alkaline hydrolysis to obtain a hydrogel product having less than 50% non-crosslinked HA molecules by weight of the hydrogel product, and
wherein the crosslinked HA molecules are free from synthetic non-carbohydrate structures and synthetic non-carbohydrate linkers.
2. The process according to claim 1 , wherein the crosslinking provides amide bonds between HA molecules and crosslinkers.
3. The process according to claim 1 , wherein the coupling agent is a triazine-based coupling reagent.
4. The process according to claim 1 , wherein hydrolyzing the ester bonds comprises swelling the crosslinked HA molecules in an alkaline solution for at least 1 hour.
5. The process according to claim 4 , further comprising:
(d) neutralizing the crosslinked HA molecules to a neutral pH;
(e) precipitating the neutralized crosslinked HA molecules;
(f) drying the precipitated crosslinked HA molecules; and
(g) swelling the dried crosslinked HA molecules in a phosphate buffer.
6. The process according to claim 1 , wherein (a) and (b) occur simultaneously.
7. The process according to claim 4 , wherein the alkaline solution comprises a hydroxide.
8. The process according to claim 1 , wherein less than 20% by weight of the hydrogel product obtained in (c) comprises HA molecules that are not crosslinked.
9. The process according to claim 1 , wherein the crosslinked HA molecules are in the form of gel particles.
10. The process according to claim 9 , wherein the gel particles are 0.01 mm to 1 mm in size.
11. The process according to claim 1 , wherein the HA molecules, prior to crosslinking, have a molecular weight of about 1,000 kDa.