Resilient foams and uses thereof

• US 10,800,905 B2
• Filed: 01/04/2019
• Issued: 10/13/2020
• Est. Priority Date: 07/24/2014
• Status: Active Grant

• Current Assignee: Smith & Nephew Incorporated (Smith & Nephew PLC)
• Original Assignee: Smith & Nephew Incorporated (Smith & Nephew PLC)
• Inventors: Delli-Santi, George T., Betre, Helawe
• Primary Examiner(s): Slifka, Colin W.
• Application Number:
  US16/240,231
• Publication Number:
  US 20190136016A1
• Time in Patent Office: 648 Days
• Field of Search: None
• CPC Class Codes: A61L 15/28 Polysaccharides or their derivatives A61L15/225 takes precedence
• CPC Class Codes: A61L 15/425 Porous materials, e.g. foams or sponges
• CPC Class Codes: A61L 15/60 Liquid-swellable gel-forming materials, e.g. super-absorbents
• CPC Class Codes: A61L 2400/04 Materials for stopping bleeding
• CPC Class Codes: A61L 2400/16 Materials with shape-memory or superelastic properties
• CPC Class Codes: A61L 27/20 Polysaccharides
• CPC Class Codes: A61L 27/52 Hydrogels or hydrocolloids
• CPC Class Codes: A61L 27/56 Porous materials, e.g. foams or sponges
• CPC Class Codes: A61L 31/042 Polysaccharides
• CPC Class Codes: A61L 31/145 Hydrogels or hydrocolloids
• CPC Class Codes: A61L 31/146 Porous materials, e.g. foams or sponges
• CPC Class Codes: C08J 2201/0484 the liquid phase being aqueous
• CPC Class Codes: C08J 2205/022 Hydrogel, i.e. a gel containing an aqueous composition
• CPC Class Codes: C08J 2205/06 Flexible foams
• CPC Class Codes: C08J 2207/10 Medical applications, e.g. biocompatible scaffolds
• CPC Class Codes: C08J 2301/08 Cellulose derivatives
• CPC Class Codes: C08J 9/28 by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum
• CPC Class Codes: C08J 9/40 Impregnation
• CPC Class Codes: C08L 1/286 substituted with acid radicals, e.g. carboxymethyl cellulose [CMC] C08L1/282 takes precedence

Abstract

Disclosed is a resilient foam and methods of making the foam. The resilient foam includes a derivatized polyanionic polysaccharide and has an open-cell structure. When the resilient foam is contacted with water, the foam forms a thixotropic hydrogel.

Claims

1. A method of preparing a resilient foam, the method comprising:

(a) obtaining a hydrogel comprising a derivatized polyanionic polysaccharide, wherein the hydrogel is a thixotropic hydrogel;

(b) subjecting the hydrogel to conditions to freeze water comprised in the hydrogel;

(c) subjecting the hydrogel from step (b) to a drying step to form an open-cell foam; and

(d) contacting the open-cell foam from step (c) with water to form the resilient foam.

2. The method of claim 1, wherein the conditions to freeze the water comprised in the hydrogel comprises subjecting the hydrogel to a temperature of 0°

C. to −

5°

C. for 1 min to 30 min.

3. The method of claim 1, wherein the drying step (b) and the freezing step (c) comprises subjecting the hydrogel in step (a) to lyophilization.

4. The method of claim 3, wherein the open-cell foam in step (d) absorbs a sufficient amount of the water contacting the open-cell foam to form the resilient foam, wherein the resilient foam is capable of being deformed upon application of pressure and returning to its original shape after removal of the pressure.

5. The method of claim 1 wherein in the derivatized polyanionic polysaccharide has a degree of substitution of less than 0.6 derivatives per monomer unit.

6. The method of claim 5, wherein the degree of substitution is between 0.2 to 0.55 derivatives per monomer unit.

7. The method of claim 5, wherein the degree of substitution is between 0.3 to 0.45 derivatives per monomer unit.

8. The method of claim 1, wherein the derivatized polyanionic polysaccharide is dissolvable in water.

9. The method of claim 1, wherein the derivatized polyanionic polysaccharide is carboxymethyl cellulose, cellulose ethyl sulfonate, carboxymethyl amylose, chondroitin-6-sulfate, chondroitin-4-sulfate, dermatan sulfate, alginate, heparin, or heparin sulfate, or any combination thereof.

10. The method of claim 1, wherein the derivatized polyanionic polysaccharide is carboxymethyl cellulose.

11. The method of claim 10, wherein the carboxymethyl cellulose compound has a molecular weight of 50 to 400 kilodaltons.

12. The method of claim 10, wherein the carboxymethyl cellulose is derived from cotton or cotton linters.

13. The method of claim 1, wherein the water comprised in the hydrogel of step (a) is in a weight ratio of the water to the derivatized polyanionic polysaccharide from 0.04 to 0.6.

14. The method of claim 1, wherein the water comprised in the resilient foam is between 20 wt. % and 60 wt. % based upon the total weigh of the resilient foam.

15. The method of claim 1, wherein at least 40 wt. % of the resilient foam is the derivatized polyanionic polysaccharide.

16. The method of claim 1, wherein the hydrogel of step (a) has a yield stress of at least 200 Pa.

17. The method of claim 1, wherein between 3 wt. % to 15 wt. % of the hydrogel is the derivatized polyanionic polysaccharide.

18. The method of claim 1 further comprising contacting water with the resilient foam to form a thixotropic hydrogel.

19. The method of claim 1, wherein the derivatized polyanionic polysaccharide is 1% or less of cross-linked polyanionic polysaccharide.