Encapsulation by cross-linking of anionic polymers by pH induced dissociation of cation-chelate complexes

Patent metadata

Field	Value
Publication number	US-12018135-B2
Application number	US-202117336766-A
Country	US
Kind code	B2
Filing date	Jun 2, 2021
Priority date	Dec 4, 2018
Publication date	Jun 25, 2024
Grant date	Jun 25, 2024

Abstract

Microencapsulation methods are provided using encapsulant, fiber or film forming compositions of a cross-linkable anionic polymer, a multivalent cation salt, a chelating agent, and a volatile base. During the formation of this composition, the generally acidic chelating agent is titrated with a volatile base to an elevated pH to improve ion-binding capability. Multivalent cations are sequestered in cation-chelate complexes. Cross-linkable polymers in this solution will remain freely dissolved until some disruption of equilibrium induces the release of the free multivalent cations from the cation-chelate complex. Vaporization of the volatile base drops the pH of the solution causing the cation-chelate complexes to dissociate and liberate multivalent cations that associate with the anionic polymer to form a cross-linked matrix. During spray-drying, the formation of a wet particle, polymer cross-linking, and particle drying occur nearly simultaneously.

First claim

What is claimed is:

1. A method of cross-linking polymer molecules, the method comprising:
(a) providing a solution of an acidic chelating agent with a volatile base;
(b) adding at least one source of multivalent cations to form cation-chelate complexes in the solution;
(c) mixing molecules of at least one anionic polymer with the solution of cation-chelate complexes and volatile base; and
(d) vaporizing the volatile base of the solution, thereby disassociating the cation-chelate complexes and releasing multivalent cations and cross-linking the polymer molecules with said multivalent cations.

2. The method of claim 1 , said acidic chelating agent solution further comprising a weak acid buffer.

3. The method of claim 2 , wherein said weak acid is an acid selected from the group consisting of benzoic acid, lactic acid, ascorbic acid, adipic acid, acrylic acid, glutaric acid, ascorbic acid, gallic acid, caffeic acid, L-Tartaric acid, D-Tartaric acid, malic acid, fumaric acid and maleic acid.

4. The method of claim 1 , wherein said chelating agent is selected from the group of chelating agents consisting of maleic acid oligomer (MAO), Phytic acid, Citric acid, hyaluronic acid and Nitrilotriacetic acid (NTA).

5. The method of claim 1 , wherein said chelating agent is selected from the group of chelating agents consisting of thioglycolic acid, 2,3, dihydroxybenzoic acid, tripolyphosphate, polyacrylic acid, acrylic acid copolymers and maleic acid copolymers.

6. The method of claim 1 , wherein said volatile base is ammonium hydroxide.

7. The method of claim 1 , wherein said volatile base is selected from the group of volatile amine bases consisting of methylamine, trimethylamine, ethylamine, diethylamine and triethylamine, isobutylamine, N, N-diisopropylethylamine, morpholine, piperazine, and ethylenediamine.

8. The method of claim 1 , wherein said source of multivalent cations is a metal salt selected from the group of multivalent metal salts consisting of calcium chloride, magnesium chloride and ferric chloride.

9. The method of claim 1 , wherein said source of multivalent cations is a trivalent metal salt selected from the group of metal salts consisting of aluminum chloride (AlCl 3 ), chromium chloride (CrCl 3 ) or ferric chloride (FeCl 3 ).

10. The method of claim 1 , wherein said polymer is selected from the group of polymers consisting of alginates, carboxymethylcellulose, carrageenan, hyaluronic acid, polygalacturonates, collagen, soy proteins and whey proteins.

11. The method of claim 1 , further comprising controlling volatile base vaporization temperatures to control rate of disassociation of cation-chelate complexes and release of multivalent cations.

12. The method of claim 1 , further comprising controlling a degree of polymer cross-linking with chelating agent concentration and multivalent ion concentration.

Assignees

• Univ California

Inventors

• Scher Herbert B
• Strobel Scott
• Zicari Tina Jeoh
• Wong Dana

Classifications

• C08K2003/162

  Calcium, strontium or barium halides, e.g. calcium, strontium or barium chloride · CPC title

• C08K5/5357

  cyclic · CPC title

• C08K5/095

  Carboxylic acids containing halogens · CPC title

• C08K3/28

  Nitrogen-containing compounds · CPC title

• C08K3/16

  Halogen-containing compounds · CPC title