Method of forming a molded protein matrix for use in a sensor

• US 7,435,569 B2
• Filed: 08/03/2004
• Issued: 10/14/2008
• Est. Priority Date: 10/23/2001
• Status: Expired due to Term

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Shah, Rajiv, Reghabi, Bahar, Zhang, Yanan, Montalvo, Rudy
• Primary Examiner(s): Naff; David M
• Application Number:
  US10/911,172
• Publication Number:
  US 20050006807A1
• Time in Patent Office: 1,533 Days
• Field of Search: None
• US Class Current: 435/177
• CPC Class Codes: C07K 1/1077 by covalent attachment of residues other than amino acids or peptide residues, e.g. sugars, polyols, fatty acids
• CPC Class Codes: C12Q 1/54 involving glucose or galactose
• CPC Class Codes: Y10S 435/817 Enzyme or microbe electrode

Abstract

A method for formulating and immobilizing a protein and a protein matrix formed by the method. The protein matrix preparation method results in a physically and chemically stable protein matrix that has low swelling, non-leaching, high activity, and high mechanical strength properties. The method includes cross-linking and hardening the protein mixture and using a mold to form a protein into a desired shape and size.

Claims

1. A method of forming a molded protein matrix comprising the steps of:

combining a protein mixture with a first cross-linking reagent;

placing the combined protein mixture and first cross-linking reagent into a mold;

incubating the combined protein mixture and cross-linking reagent in the mold to form a cross-linked and molded protein matrix;

exposing the cross-linked and molded protein matrix to a second cross-linking reagent to further cross-link the protein matrix thereby forming a hardened molded protein matrix,

wherein the second cross-linking reagent is in a vapor phase; and

contacting the protein matrix with a solution comprising a cross-linking reagent after exposing the protein matrix to the vapor phase cross-linking reagent.

2. A method according to claim 1, wherein exposing the protein matrix to a vapor phase cross-linking agent comprises exposing the protein matrix to a vapor phase that is approximately 12.5% (w/w) glutaraldehyde for approximately 16 hours.

3. A method according to claim 1, wherein incubating the protein matrix comprises maintaining the combined protein mixture and cross-linking reagent at approximately room temperature for approximately two hours.

4. A method according to claim 1, wherein contacting the protein matrix with a solution comprising a cross-linking reagent comprises submerging the protein matrix in a buffered solution that is approximately 2.5% (w/w) glutaraldehyde for approximately one hour.

5. A method according to claim 1, wherein the protein mixture comprises glucose oxidase and human serum albumin.

6. A method according to claim 1, wherein the first or second cross-linking reagent is glutaraldehyde.

7. A method according to claim 5, wherein the first or second cross-linking reagent is glutaraldehyde.

8. A method according to claim 1, wherein the first or second cross-linking reagent is selected from a group consisting of glutaraldehyde, disuccinimidyl suberate (DSS), and 1-Ethyl-3 (3-Dimethylaminopropyl) Carbodiimide (EDC).

9. A method according to claim 5, wherein the glucose oxidase has a concentration that is between approximately 67,000 U/ml and 150,000 U/ml.

10. A method according to claim 5, wherein the human serum albumin has a concentration that is between approximately 23% (w/v) and 32.5% (w/v).

11. A method according to claim 9, wherein the human serum albumin has a concentration that is between approximately 23% (w/v) and 32.5% (w/v).

12. A method according to claim 1, wherein the mold is configured to form the protein matrix into at least one elongated rope-like structure.

13. A method according to claim 12, wherein the method further comprises cutting the at least one elongated rope-like structure into pieces.

14. A method according to claim 12, wherein the elongated rope-like structure is semi-cylindrical.

15. A method according to claim 1, wherein the mold comprises:

a block with a surface wherein the surface has at least one recess in it; and

wherein the combined protein mixture and first cross-linking reagent is placed in the recess when it is placed into the mold.

16. A method according to claim 15, wherein the recess comprises at least one channel.

17. A method according to claim 16, wherein the recess is semi-cylindrical.

18. A method according to claim 16, wherein the recess comprises multiple intersecting channels.

19. A method according to claim 1, wherein the method further comprises adding silicone to the protein mixture, prior to forming a hardened molded protein matrix.

20. A method according to claim 19, wherein adding silicone to the protein mixture comprises:

obtaining silicone particles; and

adding the silicone particles to the protein mixture.

21. A method according to claim 20, wherein the volume of the silicone particles is less than 20% of the volume of the protein mixture.

22. A method according to claim 20, wherein adding the silicone particles to the protein mixture occurs prior to the protein mixture being placed into the mold.

23. A method according to claim 1, further comprising washing the hardened molded protein matrix.

24. A method according to claim 1, further comprising cutting the hardened molded protein matrix into at least two pieces after removing the protein mixture from the mold.

25. A protein matrix formed according to the method of claim 1.