Epoxy Enhanced Polymer Membrane to Increase Durability of Biosensors

• US 20060289307A1
• Filed: 08/24/2005
• Published: 12/28/2006
• Est. Priority Date: 08/24/2004
• Status: Active Grant

• Current Assignee: University of South Florida (State University System of Florida)
• Original Assignee: University of South Florida (State University System of Florida)
• Inventors: Moussy, Francis, Yu, Bazhang
• Granted Patent: US 7,534,330 B2
• Time in Patent Office: Days
• US Class Current: 204/403.10
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors
• CPC Class Codes: C12Q 1/006 for glucose
• CPC Class Codes: Y10T 428/31511 Of epoxy ether
• CPC Class Codes: Y10T 428/31529 Next to metal

Abstract

The present invention provides a polymer membrane enhanced with cured epoxy resin for use as the outer membrane of biosensors. The membrane includes approximately 30-80% epoxy resin adhesives, 10-60% polymer such as poly(vinyl chloride), polycarbonate and polyurethane and 0-30% plasticizers and 5-15% surface modifier reagent such as polyethylene oxide-containing block copolymers. Utilizing the polymer membrane of the present invention, a three-layered sensing element has been developed. This sensing element will be particularly useful for miniaturized biosensors used for in vitro blood measurements or for continuous in vivo monitoring such as implantable biosensors. This element includes an enzyme layer, an interference-eliminating layer and the novel polymer member of the present invention as the outer polymer layer. This novel sensing element shows excellent response characteristics in solutions and has an extremely long lifetime. This technology is particularly useful for improving the lifetime of implantable biosensors.

Claims

1. A coating for an implantable biosensor comprising an epoxy polymer membrane, the epoxy polymer membrane comprising an epoxy resin adhesive and a polymer whereby the epoxy polymer membrane increases the durability of the biosensor.

2. The coating of claim 1 wherein the epoxy polymer membrane comprises about 30% to about 80% by weight of polymer and about 10% to about 60% by weight of epoxy resin adhesive.

3. The coating of claim 2 wherein the epoxy polymer membrane further comprises about 5% to about 15% by weight of polyethylene oxide-containing block copolymer.

4. The coating of claim 2 further comprising up to about 30% by weight of one or more plasticizers.

5. The coating of claim 4 wherein the one or more plasticizers is selected from the group consisting of dibutyl phthalate, butyl sebacate and triphenyl phosphate.

6. The coating of claim 1 wherein the epoxy polymer membrane comprises about 40% to about 70% by weight of polymer, about 30% to about 50% by weight of epoxy resin adhesive, about 5% to about 10% by weight of polyethylene oxide-containing block copolymer and up to about 30% by weight of a plasticizer.

7. The coating of claim 1 wherein the epoxy resin adhesive is selected from the group consisting of heat-curable epoxy resin adhesives, light-curable epoxy resin adhesives and radiation-curable epoxy resin adhesives.

8. The coating of claim 1 wherein the epoxy resin adhesive is a heat-curable epoxy resin adhesive which can be cured at a temperature less than 120°

C.

9. The coating of claim 1 wherein the epoxy resin adhesive is selected from the group consisting single component epoxy resin adhesives, two component epoxy resin adhesives and multiple component epoxy resin adhesives.

10. The coating of claim 1 wherein the polymer is selected from the group consisting of polyurethane, polyester, phosphorylcholine-containing copolymer, polydimethylsiloxane, polycarbonate, poly(vinyl chloride), cellulose acetate, polyallylamine-polyaziridine, polyvinylidene chlorides, polyvinylidene-acrylonitrile copolymer, polyacrylate, polymethylacrylate and polystyrene.

11. A multilayered sensing element for biosensors comprising:

an immobilized enzyme layer formed on an electrode surface; and

an epoxy polymer layer external to the immobilized enzyme layer.

12. The multilayered sensing element of claim 11 wherein the epoxy polymer layer is about 30% to about 80% by weight of polymer and about 10% to about 60% by weight of epoxy resin adhesive.

13. The multilayered sensing element of claim 12 wherein the epoxy polymer layer further comprises about 5% to about 15% by weight of polyethylene oxide-containing block copolymer.

14. The multilayered sensing element of claim 12 wherein the epoxy polymer layer further comprises up to about 30% by weight of one or more plasticizers.

15. The multilayered sensing element of claim 11 further comprising an interference-eliminating layer spaced between the immobilized enzyme layer and the epoxy polymer layer.

16. The multilayered sensing element of claim 15 wherein the interference-eliminating layer is a persulfonate ionomer.

17. The multilayered sensing element of claim 11 wherein the enzyme of the immobilized enzyme layer is selected from the group consisting of glucose oxidase and lactate oxidase.

18. A multilayered coil-type implantable glucose sensor comprising:

an immobilized glucose oxidase enzyme layer adjacent to the surface of a coiled wire; and

an epoxy polymer layer;

the epoxy polymer layer external to the immobilized glucose oxidase enzyme layer.

19. The glucose sensor of claim 18 wherein the enzyme layer is immobilized by the technique selected from the group consisting of electropolymerization, chemical cross-linking and electropolymerization followed by chemical cross-linking.

20. The glucose sensor of claim 18 wherein the coiled wire is a platinum-iridium wire.

21. The multilayered sensing element of claim 18 wherein the epoxy polymer layer is about 35% to about 80% by weight polymer, 10% to about 60% by weight of epoxy resin adhesive and about 5% to about 15% by weight polyethylene oxide-containing block copolymer.

22. The multilayered sensing element of claim 21 wherein the epoxy polymer further comprises up to about 30% by weight of one or more plasticizers.

23. The multilayered sensing element of claim 21 further comprising an interference-eliminating layer between the immobilized enzyme layer and the epoxy polymer layer.

24. The multilayered sensing element of claim 23 wherein the interference-eliminating layer is a persulfonate ionomer.