US 4,407,957 AGranted

Reversible microencapsulation of a core material

AssigneeDamon Corporation

InventorFranklin Lim

Life of this patent

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Abstract

Disclosed is a process for microencapsulating a core material and subsequently releasing the core material by selectively disrupting the membranes of the microcapsules. The encapsulation technique involves the formation of a semipermeable membrane, e.g., around a droplet, through the formation of multiple ionic salt bonds between a polyionic polymer in the droplet and a crosslinking polyionic polymer which possesses multiple ionic groups of opposite charge. The membrane can be selectively disrupted by exposing it first to a solution of competing crosslinking multivalent (preferably di or trivalent) ions followed by a solution of a competing polyionic polymer of the same charge as the polymer in the original droplet. Alternatively, a mixed solution of the two competing solutions may be used together. For example, a membrane comprising anionic alginate salt bonded to cationic polymer can be selectively disrupted by exposing the membrane to a mixed solution of monatomic, multivalent cations, e.g. Ca++ ions, and a water-soluble polymer have plural anionic moieties, e.g., heparin, and subsequently sequestering the monatomic cations. The process may be used to encapsulate and subsequently release cell cultures without damage to the cells.

Claims18

Dependent claims

A method of encapsulating a core material within a protective environment and of subsequently releasing said core material, said method comprising:

encapsulating said core material by the steps of:
A. placing the core material in an aqueous medium which contains a water-soluble polymer containing anionic groups and having a first charge density;
B. forming the medium into droplets;
C. subjecting the droplets to a solution of multivalent cations to gel the droplets as discrete, shape-retaining, water-insoluble temporary capsules;
D. cross-linking surface layers of said temporary capsules to produce semipermeable membranes about said droplets by subjecting them to a first polymer containing cationic moieties reactive with the anionic groups of said water-soluble polymer;
and releasing said core material by the steps of:
E. exposing the capsules resulting from step D to a solution of monatomic, multivalent cations and a stripping polymer having plural anionic moieties, said stripping polymer having a charge density at least equal to said first charge density;
F. allowing said monatomic cations to compete with said first polymer for anionic groups on the water-soluble polymer and allowing said stripping polymer having plural anionic moieties to compete with said water-soluble polymer for cationic sites on said first polymer;
and
G. sequestering monatomic cations associated with said water-soluble polymer after step F.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 06/372,836Filed 28 Apr 1982 · continuation in part
Priority: 23 Oct 1978
Granted: 4 Oct 1983
Term ends: Not estimatedThe source records don’t support an estimate.

Classification12 codes

C12N 11/04
Enzymes or microbial cells immobilised on or in an organic carrier: entrapped within the carrier, e.g. gel or hollow fibres
A61K 9/1652
Organic macromolecular compounds: polysaccharides, e.g. alginate, cellulose derivatives; Cyclodextrin
A61K 9/5031
Organic macromolecular compounds: obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. polyethylene…
A61K 9/5073
Microcapsules having a gas, liquid or semi-solid filling; Solid microparticles or pellets surrounded by a distinct coating layer, e.g. coated…:…

Family

Serial953,413Parent of this continuation-in-part · filed 23 Oct 1978
Serial24,600Parent of this continuation-in-part · filed 28 Mar 1979
Serial243,584Parent of this continuation-in-part · filed 13 Mar 1981
US 4,352,883 AParent of this continuation-in-part
US 4,407,957 AThis patent

From the US filing history. Foreign family members aren’t listed.