Sustained release of encapsulated molecules

Claim 1

A method of providing controlled release of molecules encapsulated in a gelled mass with a surrounding semi-permeable membrane into a solution in which said molecules are soluble, the method comprising the steps of: A. suspending said molecules in a solution of a polyanionic polymer which can be reversibly gelled by contact with a chelatable, multivalent cationic cross-linking agent; B. gelling said polyanionic polymer by contacting said polymer with said multivalent cationic cross-linking agent to form a gelled mass with said molecules encapsulated therein; C. forming a semi-permeable membrane about said gelled mass by contacting said gelled mass with a solution of a polycationic polymer, said gelled mass within said semi-permeable membrane being in a first semi-solid gel state; D. controlling the release rate of said encapsulated molecules into said solution in which they are soluble by modifying the gel state of the gelled mass within said semi-permeable membrane from said first semi-solid gel state to a second semi-solid gel state by treating said gelled mass for a predetermined duration with a solution containing a predetermined concentration of a chelating agent, said treatment resulting in reversibly controlled modification of the gel state of said gelled mass without liquification of said gelled mass or disruption of said semi-permeable membrane, said release rate of said molecules being different from said gelled mass when in said first gel state than it is in said second gel state.

Claim 2

A method of providing controlled release of molecules encapsulated in a gelled mass with a surrounding semi-permeable membrane into a solution in which said molecules are soluble, the method comprising the steps of: A. suspending said molecules in a solution of a polyanionic polymer which can be reversibly gelled by contact with a chelatable, multivalent cationic cross-linking agent; B. gelling said polyanionic polymer by contacting said polymer with said multivalent cationic cross-linking agent to form a gelled mass with said molecules encapsulated therein; C. forming a semi-permeable membrane about said gelled mass by contacting said gelled mass with a solution of a polycationic polymer, said gelled mass within said semi-permeable membrane being in a first semi-solid gel state; D. controlling the release rate of said encapsulated molecules into said solution in which they are soluble by modifying the gel state of the gelled mass within said semi-permeable membrane from said first semi-solid gel state to a second semi-solid gel state by treating said gelled mass for a predetermined duration with a solution containing a predetermined concentration of a chelating agent, said treatment resulting in reversibly controlled modification of the gel state of said gelled mass without liquification of said gelled mass or disruption of said semi-permeable membrane, said release rate of said molecules being different from said gelled mass when in said first gel state than it is in said second gel state.

Claim 9

A method of providing controlled release of molecules encapsulated in a gelled mass with a surrounding semi-permeable membrane into a solution in which said molecules are soluble, the method comprising the steps of: A. suspending said molecules in a solution of a polyanionic polymer which can be reversibly gelled by contact with a first multivalent cationic cross-linking agent; B. gelling said polyanionic polymer by contacting said polymer with said first multivalent cationic cross-linking agent to form a gelled mass with said molecules encapsulated therein; C. forming a semi-permeable membrane about said gelled mass by contacting said gelled mass with a solution of a polycationic polymer, said gelled mass within said semi-permeable membrane being a first semi-solid gel state; D. controlling the release rate of said encapsulated molecules into said solution in which they are soluble by modifying the gel state of the gelled mass within said semi-permeable membrane from said first semi-solid gel state to a second semi-solid gel state by treating said gelled mass for a predetermined duration with a solution containing a predetermined concentration of a second multivalent cationic cross-linking agent of a different electropotential than said first multivalent cationic cross-linking agent, said treatment resulting in reversibly controlled modification of the gel state of said gelled mass without liquification of said gelled mass or disruption of said semi-permeable membrane, said release rate of said molecules being different from said gelled mass when in said first gel state than it is in said second gel state.

Claim 10

A method of providing controlled release of molecules encapsulated in a gelled mass with a surrounding semi-permeable membrane into a solution in which said molecules are soluble, the method comprising the steps of: A. suspending said molecules in a solution of a polyanionic polymer which can be reversibly gelled by contact with a first multivalent cationic cross-linking agent; B. gelling said polyanionic polymer by contacting said polymer with said first multivalent cationic cross-linking agent to form a gelled mass with said molecules encapsulated therein; C. forming a semi-permeable membrane about said gelled mass by contacting said gelled mass with a solution of a polycationic polymer, said gelled mass within said semi-permeable membrane being a first semi-solid gel state; D. controlling the release rate of said encapsulated molecules into said solution in which they are soluble by modifying the gel state of the gelled mass within said semi-permeable membrane from said first semi-solid gel state to a second semi-solid gel state by treating said gelled mass for a predetermined duration with a solution containing a predetermined concentration of a second multivalent cationic cross-linking agent of a different electropotential than said first multivalent cationic cross-linking agent, said treatment resulting in reversibly controlled modification of the gel state of said gelled mass without liquification of said gelled mass or disruption of said semi-permeable membrane, said release rate of said molecules being different from said gelled mass when in said first gel state than it is in said second gel state.