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EP-4735157-A2 - POROUS ALPHA-1,3-GLUCAN COMPOSITIONS

EP4735157A2EP 4735157 A2EP4735157 A2EP 4735157A2EP-4735157-A2

Abstract

Compositions are disclosed herein comprising an aerogel or a hydrogel. The aerogel or hydrogel comprises water-insoluble alpha-glucan and metal oxide. At least about 50% of the glycosidic linkages of the water-insoluble alpha-glucan are alpha-1,3 linkages, and the metal oxide is selected from calcium oxide, magnesium oxide, titanium dioxide, or any other suitable metal oxide. Methods of producing aerogels and hydrogels are also disclosed, as well as methods of using these materials, such as in absorption techniques. Other types of materials containing water-insoluble alpha-glucan are also disclosed.

Inventors

  • RASAKI, Sefiu A.
  • BRYANT, STEVEN L.
  • TRIFKOVIC, MILANA
  • BEHABTU, NATNAEL
  • LENGES, CHRISTIAN PETER

Assignees

  • Nutrition & Biosciences USA 4, Inc.

Dates

Publication Date
20260506
Application Date
20240627

Claims (20)

  1. 1. A composition comprising an aerogel, wherein the aerogel comprises a waterinsoluble alpha-glucan and a metal oxide, wherein at least about 50% of the glycosidic linkages of the insoluble alpha-glucan are alpha-1 ,3 linkages, and wherein the metal oxide is calcium oxide (CaO), magnesium oxide (MgO), or titanium dioxide (TiC>2).
  2. 2. The composition of claim 1 , wherein at least about 90% of the glycosidic linkages of the water-insoluble alpha-glucan are alpha-1 ,3 glycosidic linkages.
  3. 3. The composition of claim 1 , wherein the water-insoluble alpha-glucan has a weight-average degree of polymerization (DPw) of at least about 10.
  4. 4. The composition of claim 3, wherein the DPw is at least about 400.
  5. 5. The composition of claim 1 , wherein the metal oxide is said titanium dioxide (TiO 2 ).
  6. 6. The composition of claim 1 , wherein the aerogel comprises less than about 20 wt% of the metal oxide, optionally wherein the balance of the mass of the aerogel is of the water-insoluble alpha-glucan.
  7. 7. The composition of claim 1 , wherein the metal oxide interacts with the waterinsoluble alpha-glucan via hydrogen bonding.
  8. 8. The composition of claim 1 , wherein the aerogel has been comminuted.
  9. 9. The composition of claim 1 , wherein the aerogel further comprises water or an aqueous liquid, typically wherein the water or aqueous liquid was absorbed by the aerogel, optionally wherein the aerogel is under load.
  10. 10. The composition of claim 1 , wherein the composition is a personal care product, household care product, medical product, pharmaceutical product, or industrial product, and/or the composition is an absorbent product.
  11. 11. An aqueous caustic solution comprising (i) an aqueous caustic solvent, (ii) a water-insoluble alpha-glucan, and (iii) a metal hydroxide, wherein at least about 50% of the glycosidic linkages of the water-insoluble alphaglucan are alpha-1 ,3 glycosidic linkages, wherein the water-insoluble alpha-glucan is dissolved in the aqueous caustic solvent and the metal hydroxide is not dissolved in the aqueous caustic solvent, and wherein the metal hydroxide is calcium hydroxide, magnesium hydroxide, or titanium hydroxide.
  12. 12. The aqueous caustic solution of claim 11 , wherein at least about 90% of the glycosidic linkages of the water-insoluble alpha-glucan are alpha-1 ,3 glycosidic linkages.
  13. 13. The aqueous caustic solution of claim 11 , wherein the water-insoluble alphaglucan has a weight-average degree of polymerization (DPw) of at least about 10.
  14. 14. The aqueous caustic solution of claim 11 , wherein aqueous caustic solvent comprises at least one alkali hydroxide.
  15. 15. A method of producing an aerogel, said method comprising: (a) providing an aqueous caustic solution according to claim 11 , (b) putting the aqueous caustic solution into a desired form, (c) chemically or ionically modifying the aqueous caustic solvent such that the water-insoluble alpha-glucan and the metal hydroxide are undissolved in the solvent, whereby a hydrogel is produced, and (d) removing all of the water, or most of the water, from the hydrogel, whereby an aerogel is produced.
  16. 16. The method of claim 15, wherein step (a) comprises combining a salt of the metal hydroxide with an aqueous caustic solution in which the water-insoluble alphaglucan is dissolved, typically wherein the salt is provided as dissolved in an aqueous solution, and the metal hydroxide precipitates out of solution upon being combined with the aqueous caustic solution.
  17. 17. The method of claim 15, wherein step (c) comprises reducing the pH of the caustic solution to a pH that renders the water-insoluble alpha-glucan to be undissolved in the solvent.
  18. 18. The method of claim 15, wherein step (c) further comprises keeping the solution still during formation of the hydrogel.
  19. 19. The method of claim 15, wherein step (d) comprises freeze-drying or supercritical drying the hydrogel to form the aerogel.
  20. 20. An absorption method that comprises contacting a composition according to claim 1 with an aqueous liquid-comprising composition, wherein the composition absorbs aqueous liquid from said aqueous liquid-comprising composition.

Description

TITLE POROUS ALPHA-1 , 3-GLUCAN COMPOSITIONS This application claims the benefit of U.S. Provisional Appl. Nos. 63/511 ,292 (filed June 30, 2023), 63/511 ,286 (filed June 30, 2023), and 63/573,627 (filed April 3, 2024), which are each incorporated herein by reference in their entirety. FIELD The present disclosure is in the field of polysaccharides. For example, the disclosure pertains to porous compositions that comprise insoluble alpha-glucan having alpha-1 ,3 glycosidic linkages. Aerogels and hydrogels are examples of porous compositions herein. BACKGROUND Driven by a desire to use polysaccharides in various applications, researchers have explored for polysaccharides that are biodegradable and that can be made economically from renewably sourced feedstocks. One such polysaccharide is alpha- 1 ,3-glucan, an insoluble glucan polymer characterized by having alpha-1 , 3-glycosidic linkages. This polymer has been prepared, for example, using a glucosyltransferase enzyme isolated from Streptococcus salivarius (Simpson et al., Microbiology 141 : 1451 - 1460, 1995). Also for example, U.S. Patent No. 7000000 disclosed the preparation of a spun fiber from enzymatically produced alpha-1 ,3-glucan. Various other glucan materials have also been studied for developing new or enhanced applications. For example, U.S. Patent Appl. Publ. No. 2015/0232819 discloses enzymatic synthesis of several insoluble glucans having mixed alpha-1 ,3 and -1 ,6 linkages. An aerogel is a solid-state porous material derived from a gel that has been treated to replace its liquid contents with air. Generally, aerogels can contain at least about 99 wt% air, therefore qualifying them as ultra-light weight materials. Aerogels are useful in applications of absorption/adsorption, drug delivery and catalysis, for example, due to their high surface area and porosity, while their insulating properties also render them useful in thermal insulation and packaging applications. Different glucan polymers such as cellulose and chitosan have previously been tested in synthesizing aerogels, but these and other polysaccharides-based aerogels have generally been found to be prone to issues of structural discontinuity, uneven pore distribution, and formation of large pores that can cause significant shrinkage, structure collapse, and brittleness. These features can negatively impact the water retention capacity of an aerogel. Thus, aerogels made with formulations that allow better functionality are desired. Aerogels comprising alpha-1 , 3-glucan are disclosed herein, for example, to help address this need. SUMMARY In one embodiment, the present disclosure concerns a composition comprising an aerogel, wherein the aerogel comprises at least a water-insoluble alpha-glucan and a metal oxide, wherein at least about 50% of the glycosidic linkages of the insoluble alphaglucan are alpha-1 ,3 linkages, and wherein the metal oxide is calcium oxide (CaO), magnesium oxide (MgO), or titanium dioxide (TiC>2). In another embodiment, the present disclosure concerns an aqueous caustic solution comprising (i) an aqueous caustic solvent, (ii) a water-insoluble alpha-glucan, and (iii) a metal hydroxide, wherein at least about 50% of the glycosidic linkages of the water-insoluble alpha-glucan are alpha-1 ,3 glycosidic linkages, wherein the waterinsoluble alpha-glucan is dissolved in the aqueous caustic solvent and the metal hydroxide is not dissolved in the aqueous caustic solvent, and wherein the metal hydroxide is calcium hydroxide, magnesium hydroxide, or titanium hydroxide. In another embodiment, the present disclosure concerns a method/process of producing an aerogel herein, the method comprising: (a) providing an aqueous caustic solution herein, (b) putting the aqueous caustic solution into a desired form, (c) chemically or ionically modifying the aqueous caustic solvent such that the waterinsoluble alpha-glucan and the metal hydroxide are undissolved in the solvent, whereby a hydrogel is produced, and (d) removing all of the water, or most of the water, from the hydrogel, whereby an aerogel is produced. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 : This figure represents the typical scheme used herein for synthesizing hybrid hydrogels and hybrid aerogels. Refer to Examples. FIG. 2: SEM imaging of neat glucan aerogel (a) and hybrid aerogels having magnesium oxide (b), calcium oxide (c), or titanium oxide (d). Each image contains a 50- .m reference bar and an inset image with a 5- .m reference bar. Refer to Examples. FIG. 3: Water absorption by hybrid glucan and neat glucan aerogels over time. The inset chart shows water absorption of the aerogels under load. Key: neat glucan (main chart: triangles of lowest line, as indicated; inset chart: diamonds of lowest line, as indicated), MgO-glucan (circles), CaO-glucan (triangles), TiO2-glucan (squares). Refer to Examples. FIG. 4: Saline absorption by hybrid glucan and neat glucan aerogels over time. The inset chart shows saline abso