US4861627A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Preparation of multiwall polymeric microcapsules
Assignee: Massachusetts Institute of Technology
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Filing: 1987-05-01
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Granted: 1989-08-29
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Expires: 2007-05-01
Abstract
Abstract A single step method for preparation of multi-layer polymeric delivery systems. Any two or three different degradable or non-degradable polymers which are not soluble in each other at a particular concentration, as dictated by their phase diagram, can be used. The multi-layer microcapsules produced by the method are distinguished by extremely uniform dimensioned layers of polymer and actual incorporation of the substance to be delivered into the polymer layers. In the preferred embodiment of the method, two polymers are dissolved in a volatile organic solvent, the substance to be encapsulated is dispersed or dissolved in the polymer solution, the mixture is suspended in an aqueous solution and stirred, and the solvent is slowly evaporated, creating microspheres with an inner core formed by one polymer and an outer layer formed by the second polymer. In another embodiment one polymer may be formed within a layer of the other polymer by increasing the rate of evaporation of the volatile solvent.
Inventors
- 👤 Edith Mathiowitz
- 👤 Robert S. Langer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:25
CPC Classifications
A; A61; A61K; A61K9/00; A61K9/48; A61K9/50; A61K9/5089; A61K9/14; A61K9/16; A61K9/1682; A61K9/1694; Y; Y10; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2984; Y10T428/2985; Y10T428/2987; Y10T428/2989
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
105 words
A method for forming multi-layered polymeric microcapsules comprising: selecting first and second polymers, wherein the polymers are selected from the group consisting of polyanhydrides, polyorthoesters, polylactic acid, polystyrene, polyamides, ethylene vinyl acetate, polybutadiene, polyurethanes, and copolymers and combinations thereof, to form microcapsules; selecting a substance to be incorporated into said microcapsules; dissolving said polymers in a volatile solvent; adding the substance to the polymer solution; mixing the polymer and substance solution; suspending the polymer substance mixture in a nonsolvent wherein said polymers separate into distinct phases; and evaporating the volatile solvent to form microcapsules having at least one distinct polymer layer around a polymer core.
Claim 2
Independent Claim
105 words
A method for forming multi-layered polymeric microcapsules comprising: selecting first and second polymers, wherein the polymers are selected from the group consisting of polyanhydrides, polyorthoesters, polylactic acid, polystyrene, polyamides, ethylene vinyl acetate, polybutadiene, polyurethanes, and copolymers and combinations thereof, to form microcapsules; selecting a substance to be incorporated into said microcapsules; dissolving said polymers in a volatile solvent; adding the substance to the polymer solution; mixing the polymer and substance solution; suspending the polymer substance mixture in a nonsolvent wherein said polymers separate into distinct phases; and evaporating the volatile solvent to form microcapsules having at least one distinct polymer layer around a polymer core.
Claim 3
Dependent Claim
43 words
The method of claim 1 wherein the polymers are selected from the group consisting of polyanhydrides, polyorthoesters, polylactic acid, polystyrene, polyamides, ethylene vinyl acetate, polybutadiene, polyurethanes, and copolymers and combinations thereof, wherein the polymers separate on the basis of differences in molecular weight.
Claim 4
Dependent Claim
13 words
The method of claim 1 wherein the volatile solvent is an organic solvent.
Claim 5
Dependent Claim
30 words
The method of claim 1 wherein the first polymer is dissolved in a first solvent and the second polymer is dissolved in a second solvent prior to combining the polymers.
Claim 6
Dependent Claim
19 words
The method of claim 4 wherein a first substance to be incorporated is added to the first polymer solution.
Claim 7
Dependent Claim
16 words
The method of claim 5 wherein a second substance is added to the second polymer solution.
Claim 8
Dependent Claim
18 words
The method of claim 1 wherein the first and second polymers are dissolved together in a first solvent.
Claim 9
Dependent Claim
14 words
The method of claim 1 further comprising forming additional polymer layers around said microcapsules.
Claim 10
Dependent Claim
14 words
The method of claim 1 further comprising adding other polymers to the polymer-substance solution.
Claim 11
Dependent Claim
12 words
The method of claim 1 wherein said nonsolvent is an aqueous solution.
Claim 12
Dependent Claim
19 words
The method of claim 10 further comprising adding between 0 and 10% surface active agent to the aqueous solution.
Claim 13
Dependent Claim
13 words
The method of claim 11 wherein the surface active agent is an emulsifier.
Claim 14
Dependent Claim
20 words
The method of claim 1 wherein the volatile solvents are evaporated at a temperature between 0° C. and 60° C.
Claim 15
Dependent Claim
25 words
The method of claim 1 wherein said solvent is rapidly evaporated to form spheres of said first polymer within a layer of said second polymer.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-08-28 | 1993-02-27 | 1993-08-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-08-28 | 1997-02-27 | 1997-08-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-08-28 | 2001-02-27 | 2001-08-29 | $7700.00 | Window Closed / Lapsed |