University of California

Tina Jeoh Zicari

Herbert Benson Scher

Scott Strobel

Monica C Santa-Maria

Dana Wong

Yuting Tang

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.

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

An industrially scalable microcapsule, fiber or film forming process and formulations suitable for use in conventional spray drying systems are provided. The one-step spray drying process utilizes formulations of a first ionic polymer, a second ionic polymer with an isoelectric point (pI) or acid dissociation constant (pKa) that is greater than the isoelectric point (pI) or acid dissociation constant (pKa) of the first ionic polymer and a volatile base or volatile acid. Volatilization of the volatile base or acid of the spray formulation changes the pH of the solution and changes the charge of the second ionic polymer initiating electrostatic interactions with the first ionic polymer through complex coacervation. Microcapsules formed by the complex coacervation process can stabilize bioactive components as well as control the release of the bioactive components for a variety of applications.

Microencapsulation of chemicals and bioactives by in situ complex coacervation during spray drying

Microencapsulation of bioactive and chemical cargo in a stable, cross-linked polymer matrix is presented that results in small particle sizes and is easily scaled-up for industrial applications. A formulation of a salt of an acid soluble multivalent ion, an acid neutralized with a volatile base and one or more monomers that cross-link in the presence of multivalent ions is atomized into droplets. Cross-linking is achieved upon atomization where the volatile base is vaporized resulting in a reduction of the pH of the formulation and the temporal release of multivalent ions from the salt that cross-link the monomers forming a capsule. The incorporation of additional polymers or hydrophobic compounds in the formulation allows control of hydration properties of the particles to control the release of the encapsulated compounds. The operational parameters can also be controlled to affect capsule properties such as particle-size and particle-size distribution.

Spray dry method for encapsulation of biological moieties and chemicals in polymers cross-linked by multivalent ions for controlled release applications

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Davis, CA, United States of America

Tina Jeoh Zicari