Preparation of multiwall polymeric microcapsules
First Claim
1. 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.
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Accused Products
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.
442 Citations
14 Claims
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1. A method for forming multi-layered polymeric microcapsules comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification