System for controlled release of biologically active compounds
First Claim
1. A system for controlled release of a biologically-active substance comprising:
- (a) microcapsules having an inner polysaccharide polymer core and an outer ionically interacting skin;
(b) a biologically-active substance; and
(c) an enzyme, said enzyme specifically degrading said core polysaccharide and not the ionically interacting skin;
wherein said biologically-active substance and said enzyme are encapsulated in said microcapsules, said enzyme degrading said core polysaccharide until the outer skin loses its integrity, the microcapsules completely break down and said biologically-active substance is released.
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Abstract
A controlled release system for delivery of a biologically-active substance. In one embodiment, there is a delayed release of a biologically-active substance. In a second embodiment, the delayed release is preceded by an initial release of biologically active substance. In other variations of the system, there are mulitple discrete releases over time or a continuous slow release combined with discrete releases. The delayed exposure is achieved through the design and construction of the system, specifically, formation of ionically-coated microcapsules around the biologically-active substance in conjunction with a microcapsule core-degrading enzyme. Release of active substance takes place in a burst at such a time as the core degrading enzyme has reduced the core to a molecular weight too low to support enough interaction with the cationic skin to maintain its integrity as a skin. In one example, microcapsules are formed of an ionically cross-linked polysaccharide, calcium alginate, which is further ionically coated with a poly-cationic skin of poly-L-lysine. The capsule coating serves a dual purpose: to control diffusion of the biologically-active substance and the core-degrading enzyme and as a substrate for the mechanism by which the biologically-active substance is released after a time delay.
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Citations
25 Claims
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1. A system for controlled release of a biologically-active substance comprising:
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(a) microcapsules having an inner polysaccharide polymer core and an outer ionically interacting skin; (b) a biologically-active substance; and (c) an enzyme, said enzyme specifically degrading said core polysaccharide and not the ionically interacting skin; wherein said biologically-active substance and said enzyme are encapsulated in said microcapsules, said enzyme degrading said core polysaccharide until the outer skin loses its integrity, the microcapsules completely break down and said biologically-active substance is released. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for controlled release of a biologically-active substance comprising:
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encapsulating the biologically-active substance and an enzyme within microcapsules, wherein said microcapsules are formed of an inner polysaccharide core and an outer ionically interacting skin, and said enzyme specifically degrades said polysaccharide core, locating said microcapsules at the site where controlled release is to occur, and reacting said encapsulated enzyme with said polysaccharide core to alter the integrity of said ionically interacting skin to completely break down the microcapsules and effect release of the biologically active substance from the microcapsules. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A method for immunizing an animal comprising:
encapsulating an antigen and an enzyme within microcapsules, wherein said microcapsules are formed of an inner core polysaccharide and an outer ionically interacting skin and said enzyme specifically degrades said core polysaccharide of the microcapsules to effect complete break down of the microcapsules and release of said encapsulated antigen, and injecting said microcapsules into the animal to be immunized. - View Dependent Claims (23, 24, 25)
Specification