METHODS OF MAKING HYALURONIC ACID/COLLAGEN COMPOSITIONS
Hyaluronic acid and collagen may be crosslinked in aqueous solution as described herein. The crosslinked macromolecular matrices obtained in this process may be used as a hydrogel for implants and fillers for human aesthetic and therapeutic products.
1 - 10 . (canceled)
11 . A method of crosslinking hyaluronic acid and collagen comprising:
dissolving a hyaluronic acid and a collagen in an aqueous solution to form an aqueous pre-reaction solution, wherein the aqueous pre-reaction solution further comprises a salt or has a pH less than about 4; and
modifying the aqueous pre-reaction solution to form a crosslinking reaction mixture comprising:
the hyaluronic acid;
the collagen;
a water soluble carbodiimide;
an N-hydroxysuccinimide or an N-hydroxysulfosuccinimide; and
the salt; and
wherein the crosslinking reaction has a higher pH than the aqueous pre-reaction solution; and
allowing the crosslinking reaction mixture to react to thereby crosslink the hyaluronic acid and the collagen.
12 . The method of claim 11 , wherein modifying the aqueous pre-reaction solution to form a crosslinking reaction mixture comprises increasing the pH of the aqueous pre-reaction solution and allowing a substantial amount of fiber formation to occur before adding the water soluble carbodiimide.
13 . The method of claim 11 , wherein modifying the aqueous pre-reaction solution to form a crosslinking reaction mixture comprises adding the water soluble carbodiimide to the aqueous pre-reaction solution before substantially any fiber formation occurs.
14 . The method of claim 11 , wherein the salt comprises sodium chloride at a concentration of about 80 mM to about 330 mM in the crosslinking reaction mixture.
15 . The method of claim 11 , wherein the water soluble carbodiimide is 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide at a concentration of about 20 mM to about 100 mM in the crosslinking reaction mixture.
16 . The method of claim 11 , wherein the crosslinking reaction mixture further comprises a non-coordinating buffer having a concentration of about 10 mM to about 1 M.
17 . The method of claim 11 , further comprising particulating the crosslinked macromolecular matrix through a mesh having a pore size of about 10 microns to 100 microns.
18 . The method of claim 11 , further comprising sterilizing the crosslinked molecular matrix by dialysis;
wherein the dialysis is against a sterile phosphate buffer solution comprising phosphate buffer, potassium chloride, and sodium chloride, wherein the sterile phosphate buffer solution is substantially isosmotic with respect to human physiological fluid; and
wherein the dialysis is through a membrane having a molecular weight cutoff of about 5,000 daltons to about 100,0000 daltons.
19 - 24 . (canceled)