Selectively permeable coated membrane

1. An implantable analyte sensor comprising a biointerface membrane permitting selective diffusion of an analyte therethrough, said membrane comprising a nanoporous substrate and a coating on said nanoporous substrate restricting a pore size of the nanoporous substrate, said coating comprising a plurality of bio-compatible polymer chains, whereby each polymer chain is covalently attached at one chain end thereof to a surface of the nanoporous substrate via a 5-(2-bromo-2-methylpropanamido)-2-hydroxybenzoic acid group and whereby the polymer chains are formed by a surface-initiated controlled polymerization process from the nanoporous substrate.

2. The sensor according to claim 1 , wherein the sensor is a glucose sensor.

3. The sensor according to claim 1 , wherein the polymer chains are formed by polymerisation of one or more monomer selected from the group consisting of 2-hydroxyethyl methacrylate, glycidyl methacrylate, (polyethylene glycol) methacrylate, (polyethylene glycol) methylether methacrylate, ethylene glycol dimethacrylate, and poly(ethylene glycol)dimethacrylate.

4. The sensor according to claim 3 , wherein the polymer chains are composed of poly(poly(ethylene glycol) methacrylate) chains.

5. The sensor according to claim 1 , wherein the substrate is a nanoporous alumina substrate.

6. The sensor according to claim 5 , wherein the nanoporous substrate has a pore size of at least 20 nm and no more than 100 nm.

7. The sensor according to claim 1 , wherein the nanoporous substrate has a pore size of at least 2 nm and no more than 200 nm.

8. The sensor according to claim 1 , wherein the coating of the nanoporous substrate has a thickness of at least 10 nm and no more than 100 nm.

9. The sensor according to claim 1 , wherein the membrane has a pore size in the range of from 0.1 nm to 10 nm.

10. The implantable analyte sensor according to claim 1 , wherein said polymer chains comprise water soluble monomers.

11. A bio-interface membrane for an analyte sensor permitting selective diffusion of an analyte therethrough comprising:

a nanoporous substrate and a coating on said nanoporous substrate, said coating comprising a plurality of bio-compatible polymer chains, whereby each polymer chain is covalently attached at one chain end thereof to a surface of the nanoporous substrate via a 5-(2-bromo-2-methylpropanamido)-2-hydroxybenzoic acid group and whereby the polymer chains are formed by a surface-initiated controlled polymerization process from the nanoporous substrate, said coating restricting a pore size of the pores of the nanoporous substrate so as to provide selective diffusion of the analyte through the membrane.

12. The membrane according to claim 11 , wherein the analyte is glucose.

13. The membrane according to claim 11 , wherein the polymer chains are formed by polymerisation of one or more monomer selected from the group consisting of 2-hydroxyethyl methacrylate, glycidyl methacrylate, (polyethylene glycol) methacrylate, (polyethylene glycol) methylether methacrylate, ethylene glycol dimethacrylate, and poly(ethylene glycol)dimethacrylate.

14. The membrane according to claim 13 , wherein the polymer chains are composed of poly(poly(ethylene glycol) methacrylate) chains.

15. The membrane according to claim 11 , wherein the substrate is a nanoporous alumina substrate.

16. The membrane according to claim 15 , wherein the nanoporous substrate has a pore size of at least 20 nm and no more than 100 nm.

17. The membrane according to claim 11 , wherein the nanoporous substrate has a pore size of at least 2 nm and no more than 200 nm.

18. The membrane according to claim 11 , wherein the coating of the nanoporous substrate has a thickness of at least 10 nm and no more than 100 nm.

19. The membrane according to claim 11 , wherein the membrane has a pore size in the range of from 0.1 nm to 10 nm.

20. The membrane according to claim 11 , wherein said polymer chains comprise water soluble monomers.

21. A method for the preparation of a selectively permeable biointerface membrane for use in an analyte sensor, comprising chemically binding a monolayer of an initiator group onto a surface of a nanoporous substrate, and subsequently carrying out a polymerisation by a surface-initiated controlled polymerization process from the monolayer of said initiator group to form a coating on the nanoporous substrate comprising a plurality of bio-compatible polymer chains, whereby each polymer chain is attached at one chain end thereof to a surface of the nanoporous substrate via a 5-(2-bromo-2-methylpropanamido)-2-hydroxybenzoic acid group, said coating restricting a pore size of the nanoporous substrate so as to provide selective diffusion of an analyte through the membrane, wherein said surface-initiated controlled polymerization process comprises surface initiated atom transfer radical polymerisation.

22. The method according to claim 21 , wherein the nanoporous substrate is a nanoporous alumina substrate.

23. The method according to claim 22 , wherein the nanoporous substrate has a pore size of at least 20 nm and no more than 100 nm.

24. The method according to claim 21 , wherein the nanoporous substrate has a pore size of at least 2 nm and no more than 200 nm.

25. The method according to claim 21 , wherein the coating of the nanoporous substrate has a thickness of at least 10 nm and no more than 100 nm.

26. The method according to claim 21 , wherein the thickness of the nanoporous coating is controlled by controlling the length of time of the polymerisation.

27. The method according to claim 21 , wherein the polymer chains are formed by polymerisation of one or more monomer selected from the group consisting of 2-hydroxyethyl methacrylate, glycidyl methacrylate, (polyethylene glycol) methacrylate, (polyethylene glycol) methylether methacrylate, ethylene glycol dimethacrylate, and poly(ethylene glycol)dimethacrylate.

28. The method according to claim 27 , wherein the polymer chains are composed of poly(poly(ethylene glycol) methacrylate) chains.

29. The method according to claim 21 , wherein said polymer chains comprise water soluble monomers.