Silicone based membranes for use in implantable glucose sensors

• US 20060258761A1
• Filed: 04/14/2006
• Published: 11/16/2006
• Est. Priority Date: 05/22/2002
• Status: Abandoned Application

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Shults, Mark C., Boock, Robert, Tapsak, Mark A., Rhodes, Rathbun K., Rixman, Monica
• Time in patent office: 0 Days
• US Class Current: 521/50
• 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: A61B 5/6848 Needles
• CPC Class Codes: B01D 69/141 Heterogeneous membranes, e.g. containing dispersed material; Mixed matrix membranes
• CPC Class Codes: B01D 71/54 Polyureas; Polyurethanes
• CPC Class Codes: B01D 71/80 Block polymers
• CPC Class Codes: C08G 77/12 containing silicon bound to hydrogen C08G77/045 takes precedence
• CPC Class Codes: C08G 77/20 containing silicon bound to unsaturated aliphatic groups C08G77/045 takes precedence
• CPC Class Codes: C08G 77/46 containing polyether sequences
• CPC Class Codes: C08L 2666/14 Macromolecular compounds according to C08L59/00 - C08L87/00; Derivatives thereof
• CPC Class Codes: C08L 83/04 Polysiloxanes
• CPC Class Codes: C12Q 1/002 Electrode membranes

Abstract

Membrane systems incorporating silicone polymers are described for use in implantable analyte sensors. Some layers of the membrane system may comprise a blend of a silicone polymer with a hydrophilic polymer, for example, a triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) polymer. Such polymeric blends provide for both high oxygen solubility and aqueous analyte solubility.

Claims

1. A membrane layer for use in an analyte sensor, comprising a blend of a silicone polymer with a co-polymer comprising a polymeric hydrophobic domain and a polymeric hydrophilic domain, wherein the membrane is adapted to permit diffusion of both the analyte and oxygen therethrough.

2. The membrane layer of claim 1, wherein the silicone polymer is a dimethyl- and methylhydrogen-siloxane copolymer.

3. The membrane layer of claim 2, wherein the silicone polymer comprises vinyl substituents.

4. The membrane layer of claim 1, wherein the silicone polymer is a polymer produced by curing a MED-4840 mixture.

5. The membrane layer of claim 1, wherein the co-polymer comprises poly(ethylene oxide) and poly(propylene oxide).

6. The membrane layer of claim 5, wherein the copolymer comprises hydroxy substituents.

7. The membrane layer of claim 1, wherein the analyte is glucose.

8. The membrane layer of claim 1, wherein at least a portion of the co-polymer is cross-linked.

9. An implantable analyte sensor, comprising:

an electrode adapted to directly or indirectly detect the analyte; and

at least one membrane layer positioned over the electrode comprising a blend of a silicone polymer with a co-polymer comprising a polymeric hydrophobic domain and a polymeric hydrophilic domain.

10. The sensor of claim 9, comprising an enzyme layer positioned over the electrode, the enzyme layer comprising an enzyme for which the analyte is a substrate.

11. The sensor of claim 10, wherein the enzyme layer is one of said at least one membrane layer.

12. The sensor of claim 10, wherein one of said at least one membrane layer is positioned between the enzyme layer and tissue adjacent to the sensor when implanted.

13. The sensor of claim 10, comprising a diffusion resistance layer positioned between the enzyme layer and tissue adjacent to the sensor when implanted.

14. The sensor of claim 13, wherein at least one of the enzyme layer and the diffusion resistance layer is one of said at least one membrane layer.

15. The sensor of claim 13, wherein the diffusion resistance layer is one of said at least one membrane layer.

16. The sensor of claim 13, comprising a bioprotective layer positioned between the diffusion resistance layer and tissue adjacent to the sensor when implanted.

17. The sensor of claim 16, wherein at least one of the enzyme layer, the diffusion resistance layer, and the bioprotective layer is one of said at least one membrane layer.

18. The sensor of claim 16, wherein the bioprotective layer is one of said at least one membrane layer.

19. The sensor of claim 16, comprising a cell disruptive layer positioned between the bioprotective layer and tissue adjacent to the sensor when implanted.

20. The sensor of claim 19, wherein at least one of the enzyme layer, the bioprotective layer, the diffusion resistance layer, and the cell disruptive layer is one of said at least one membrane layer.

21. The sensor of claim 19, wherein the cell disruptive layer is one of said at least one membrane layer.

22. The sensor of claim 19, wherein the cell disruptive layer is substantially porous.

23. The sensor of claim 19, wherein the cell disruptive layer is a silicone polymer.

24. The sensor of claim 19, comprising an electrode layer positioned between the electrode and the enzyme layer, wherein the electrode layer is adapted to maintain a layer of aqueous electrolyte at the electrode'"'"'s surface.

25. The sensor of claim 24, wherein at least one of the enzyme layer, the bioprotective layer, the diffusion resistance layer, the cell disruptive layer, and the electrode layer is one of said at least one membrane layer.

26. The sensor of claim 24, wherein the electrode layer is one of said at least one membrane layer.

27. The sensor of claim 24, wherein the electrode layer comprises a hydrogel.

28. The sensor of claim 9, wherein the silicone polymer is a dimethyl- and methylhydrogen-siloxane copolymer.

29. The sensor of claim 9, wherein the co-polymer comprises poly(ethylene oxide) and poly(propylene oxide).

30. An implantable analyte sensor, comprising:

an enzyme layer comprising an enzyme for which the analyte is a substrate; and

a bioprotective layer positioned between the enzyme layer and tissue adjacent to the sensor when implanted, wherein the bioprotective layer comprises a blend of a silicone polymer with a co-polymer comprising a polymeric hydrophobic domain and a polymeric hydrophilic domain.

31. The sensor of claim 30, further comprising a diffusion resistance layer positioned between the enzyme layer and the bioprotective layer.

32. The sensor of claim 31, wherein the diffusion resistance layer also comprises a blend of the silicone polymer with the co-polymer, wherein the ratio of the silicone polymer to the co-polymer is different in the diffusion resistance layer than in the bioprotective layer.

33. The sensor of claim 30, wherein the sensor does not comprise an additional diffusion resistance layer and the bioprotective layer is adapted to have diffusion resistance characteristics.

34. The sensor of claim 30, wherein the silicone polymer is a dimethyl- and methylhydrogen-siloxane copolymer.

35. The sensor of claim 30, wherein the co-polymer comprises poly(ethylene oxide) and poly(propylene oxide).

36. An implantable analyte sensor, comprising:

an enzyme layer comprising an enzyme for which the analyte is a substrate; and

a diffusion resistance layer positioned between the enzyme layer and tissue adjacent to the sensor when implanted, wherein the diffusion resistance layer comprises a blend of a silicone polymer with a co-polymer comprising a polymeric hydrophobic domain and a polymeric hydrophilic domain.

37. The sensor of claim 36, wherein at least a portion of the diffusion resistance layer is porous and adjacent to tissue when implanted.

38. The sensor of claim 36, wherein the ratio of the silicone elastomer to co-polymer varies within the diffusion resistance layer.

39. The sensor of claim 36, further comprising a bioprotective layer positioned between the diffusion resistance layer and tissue adjacent to the sensor when implanted.

40. The sensor of claim 39, wherein the bioprotective layer also comprises a blend of the silicone polymer with the co-polymer, wherein the ratio of the silicone polymer to the co-polymer is different in the diffusion resistance layer than in the bioprotective layer.

41. The sensor of claim 36, wherein the sensor does not comprise an additional bioprotective layer and the diffusion resistance layer is adapted to have bioprotective characteristics.

42. The sensor of claim 36, further comprising a silicone cell disruptive layer positioned between the diffusion resistance layer and tissue adjacent to the sensor when implanted.

43. The sensor of claim 36, wherein the silicone polymer is a dimethyl- and methylhydrogen-siloxane copolymer.

44. The sensor of claim 36, wherein the co-polymer comprises poly(ethylene oxide) and poly(propylene oxide).