Two-layer analyte sensor

1. An analyte sensor comprising:

a sensing membrane comprising:

a crosslinked network comprising one or more proteins and crosslinks, wherein

the proteins are crosslinked through carbon-nitrogen double bonds between amine group nitrogen atoms on the proteins and carbon atoms on the crosslinks; and

an analyte sensing component embedded in the crosslinked network;

a protective membrane adjacent to a surface of the sensing membrane, comprising

backbone chains comprising:

first methacrylate-derived units, each having a hydrophilic side chain;

second methacrylate-derived units, each having a hydrophilic side chain comprising one or more alkylene oxide unit; and

third methacrylate-derived units; and

hydrophilic crosslinks between the third methacrylate-derived units in different backbone chains, wherein the hydrophilic crosslinks comprise poly(alkylene oxide).

2. The analyte sensor of claim 1 , wherein in the crosslinks of the sensing membrane are C 2 -C 6 alkyl.

3. The analyte sensor of claim 1 , wherein the crosslinks of the sensing membrane comprise one or more alkylene oxide unit.

4. The analyte sensor of claim 1 , wherein the proteins of the sensing membrane are bovine serum albumin.

5. The analyte sensor of claim 1 , wherein the analyte sensing component of the sensing membrane comprises glucose oxidase.

6. The analyte sensor of claim 1 , wherein the sensing membrane is adjacent to a surface of an electrode.

7. The analyte sensor of claim 6 , wherein the sensing membrane is between the electrode and the protective membrane.

8. The analyte sensor of claim 1 , wherein the first methacrylate-derived units of the protective membrane have the structure of formula (IIa):

wherein

X is —O—, —NR″— or —S—;

y is 0-10; and

R 1 is hydrogen, —C 1 -C 12 alkyl, —C 1 -C 12 alkyl-OH, —SiR″ 3 , —C(O)—C 1 -C 12 alkyl, —C 1 -C 12 alkyl-C(O)OR″, wherein R″ is —C 1 -C 12 alkyl.

9. The analyte sensor of claim 8 , wherein the first methacrylate-derived units of the protective membrane have the structure:

10. The analyte sensor of claim 1 , wherein the second methacrylate-derived units of the protective membrane have the structure of formula (III):

wherein

Y is —O—, —NR″— or —S—;

R 2 is hydrogen, —C 1 -C 12 alkyl, —SiR″ 3 , —C(O)—C 1 -C 12 alkyl, —C 1 -C 12 alkyl-C(O)OR″,

where R″ is hydrogen or —C 1 -C 12 alkyl; and

x is 1-10.

11. The analyte sensor of claim 1 , wherein the second methacrylate-derived units of the protective membrane have the structure of formula: (III):

wherein

Y is —O—, —NR″— or —S—;

R 2 is hydrogen, —C 1 -C 12 alkyl, —SiR″ 3 , —C(O)—C 1 -C 12 alkyl, —C 1 -C 12 alkyl-C(O)OR″,

where R″ is hydrogen or —C 1 -C 12 alkyl; and

x is an average value of from 2 to about 250.

12. The analyte sensor of claim 1 , wherein the protective membrane has a thickness of about 20 μm.

13. The analyte sensor of claim 1 , wherein

the proteins of the sensing membrane are BSA;

the crosslinks of the sensing membrane are C 2 -C 6 alkyl;

the analyte sensing component of the sensing membrane comprises glucose oxidase.

14. The analyte sensor of claim 1 , wherein

the first methacrylate-derived units of the protective membrane are derived from 2-hydroxyethylmethacrylate;

the second methacrylate-derived units of the protective membrane have the structure of formula (III):

wherein

Y is —O—, —NR″— or —S—;

R 2 is hydrogen, —C 1 -C 12 alkyl, —SiR″ 3 , —(O)—C 1 -C 12 alkyl-C(O)OR″, where R″ is hydrogen or —C 1 -C 12 alkyl; and

x is an average value of from about 10 to about 15; and

the hydrophilic crosslinks of the protective membrane have the structure of formula (IVa):

wherein z is 2-10.

15. The analyte sensor of claim 1 , wherein

the proteins of the sensing membrane are BSA;

the crosslinks of the sensing membrane are C 5 alkyl;

the analyte sensing component of the sensing membrane comprises glucose oxidase;

the first methacrylate-derived units of the protective membrane are derived from 2-hydroxyethylmethacrylate;

the second methacrylate-derived units of the protective membrane have the structure of formula (III):

wherein x is an average value of from about 10 to about 15; and

the hydrophilic crosslinks of the protective membrane have the structure of formula (IVa):

wherein z is 2-10.

16. The analyte sensor of claim 1 , wherein the hydrophilic crosslinks of the protective membrane have the structure of formula (IVa):

wherein z is an average value of from about 2 to about 250.

17. The analyte sensor of claim 1 , wherein

the first methacrylate-derived units of the protective membrane are derived from 2-hydroxyethylmethacrylate;

the second methacrylate-derived units of the protective membrane have the structure of formula (III):

wherein

Y is —O—, —NR″— or —S—;

R 2 is hydrogen, —C 1 -C 12 alkyl, —SiR″ 3 , —C(O)—C 1 -C 12 alkyl, —C 1 -C 12 alkyl-C(O)OR″, where R″ is hydrogen or —C 1 -C 12 alkyl; and

x is an average value of from about 10 to about 15; and

the hydrophilic crosslinks of the protective membrane have the structure of formula (IVa):

wherein z is an average value of from about 2 to about 250.

18. A method for manufacturing an analyte sensor, the method comprising:

forming a sensing mixture comprising one or more proteins, a crosslinking agent, and an analyte sensing component, wherein the proteins have one or more amine functional groups;

depositing the sensing mixture onto a surface of an electrode;

curing the deposited sensing mixture to provide a sensing membrane;

forming a copolymer mixture comprising an initiator, a first methacrylate monomer having a hydrophilic side chain comprising one or more alkylene oxide unit, a dimethacrylate monomer, and a second methacrylate monomer having a hydrophilic side chain, wherein the dimethacrylate monomer comprises two terminal methacrylate groups tethered by a hydrophilic linker comprising poly(alkylene oxide);

depositing the copolymer mixture onto a surface of the sensing membrane; and

curing the deposited copolymer mixture to provide a protective membrane.