Biocompatible and bioabsorbable derivatized chitosan compositions
View Patent ↗The invention relates to biocompatible, bioabsorbable derivatized non-crosslinked chitosan compositions optionally crosslinked to gelatin/collagen by 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride (EDC) for biomedical use and methods of making and testing such compositions, including a modified acute systemic toxicity test. The compositions comprise derivatized chitosan reacetylated to a degree of N-deacetylation (DDA) of between about 15% and 40%. The compositions are typically bioabsorbed in about 90 days or less and can be made to bioabsorb at differing rates of speed. The compositions are initially soluble in aqueous solution below pH 6.5. The compositions have an acid content that can be adjusted between about 0% (w/w) and about 8% (w/w) to customize the composition for uses that require and/or tolerate differing levels of cytotoxicity, adhesion, composition cohesion, and cell infiltration into the composition.
1. A biocompatible, bioabsorbable deacetylated and reacetylated chitosan composition comprising a reacetylated chitosan having a molecular weight of at least about 90 kDa to about 170 kDa and a degree of N-deacetylation of between about 15% and 40% cross-linked with at least one of gelatin and collagen.
2. The composition of claim 1 , further comprising an acid content between about 0% (w/w) and 8% (w/w).
3. The composition of claim 1 , wherein the ratio of chitosan to gelatin is selected from a group consisting of about 1:1, about 2:1, and about 3:1.
4. The composition of claim 1 , wherein the composition is capable of in vivo bioabsorption in less than about 90 days.
5. The composition of claim 4 , wherein the composition is at least 85% absorbed.
6. The composition of claim 1 , wherein the composition has a degree of N-deacetylation of between about 15% to 30%.
7. The composition of claim 1 , wherein the composition comprises one of a freeze-dried sponge, a freeze-dried foam, a non-freeze-dried foam, an implant, a tissue scaffold, an implant device surface coating, a matrix, a fiber, a powder, a sheet, a film, a membrane, a nanofiber, a nanoparticle, and a hydrogel.
8. A method of making a biocompatible, bioabsorbable chitosan composition comprising:
obtaining deacetylated chitosan;
producing reacetylated chitosan from the deacetylated chitosan having a degree of N-deacetylation of between about 15% and 40%;
resolubilizing the reacetylated chitosan having a degree of N-deacetylation of between about 15% and 40% into an acidified aqueous solution;
volatilizing residual acid bound to the reacetylated chitosan having a degree of N-deacetylation of between about 15% and 40%; and
allowing an acid content between about 2% (w/w) and 8% (w/w) to remain.
9. The method of claim 8 , further comprising selecting a deacetylated chitosan starting material having a purity of at least 99%.
10. The method of claim 8 , further comprising reducing chitosan free amine functionality of deacetylated chitosan by at least one of reacetylation and derivatization of the glucosamine C-2 nitrogen with an electrophile.
11. The method of claim 8 , further comprising cross-linking the composition by combining the reacetylated chitosan acidified aqueous solution and a gelatin aqueous solution.
12. The method of claim 8 , further comprising cross-linking the reacetylated chitosan having a degree of N-deacetylation of between about 15% and 40% with at least one of gelatin and collagen.
13. The method of claim 12 , further comprising using 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride to accomplish the cross-linking.
14. The method of claim 8 , further comprising processing the composition into a form selected from a group consisting of a freeze-dried sponge, a freeze-dried foam, a non-freeze-dried foam, an implant, a tissue scaffold, an implant device surface coating, a matrix, a fiber, a powder, a sheet, a film, a membrane, a nanofiber, a nanoparticle, and a hydrogel.
15. The composition of claim 1 , further comprising an acid content between about 2% (w/w) and 5% (w/w).
16. The composition of claim 1 , wherein the composition is freeze-dried.
17. The composition of claim 1 , wherein the composition is foamed.
18. The composition of claim 1 , wherein the reacetylated chitosan has a molecular weight of about 170 kDa.
19. The method of claim 8 , further comprising allowing an acid content of between about 2% (w/w) and 5% (w/w) to remain.
20. The method of claim 8 , wherein the deacetylated chitosan has a degree of N-deacetylation of between 90% and about 100%.
21. The method of claim 8 , further comprising resolubilizing the reacetylated chitosan having a degree of N-deacetylation of between about 15% and 40% into aqueous solution using carbonic acid.
22. The method of claim 8 , further comprising at least one of freeze-drying and foaming the reacetylated chitosan having a degree of N-deacetylation of between about 15% and 40%.
23. The method of claim 8 , wherein reacetylated chitosan having a degree of N-deacetylation of between about 15% and 30% is produced and is either volatilized or washed with water.
24. A biocompatible, bioabsorbable deacetylated and reacetylated chitosan composition having a degree of N-deacetylation of between about 15% and 30%.
25. A biocompatible, bioabsorbable deacetylated and reacetylated chitosan composition having a degree of N-deacetylation of between about 15% and 40% comprising an acid content between about 2% (w/w) and 5% (w/w).
26. The method of claim 8 , wherein the deacetylated chitosan has a degree of N-deacetylation of between 95% and about 100%.
27. The composition of claim 1 , further comprising an acid content between about 1% (w/w) and 5% (w/w).
28. The composition of claim 1 , wherein the composition has a degree of N-deacetylation of between about 20% to 30%.
29. The method of claim 8 , wherein reacetylated chitosan having a degree of N-deacetylation of between about 20% and 30% is produced and is either volatilized or washed with water.
30. The composition of claim 1 , wherein the composition comprises chitosan that is initially soluble in an aqueous solution below or at about pH 6.5.