Method for manufacture of lactate biosensing strip

• US 7,364,873 B2
• Filed: 12/06/2005
• Issued: 04/29/2008
• Est. Priority Date: 01/15/2003
• Status: Expired due to Fees

• Current Assignee: Council of Scientific & Industrial Research
• Original Assignee: Council of Scientific & Industrial Research
• Inventors: Sharma, Rajendra Kumar, Chaubey, Asha, Malhotra, Bansi Dhar, Pandey, Manoj Kumar, Pande, Krishan Kant, Rajesh, Saini, Krishan Kumar
• Primary Examiner(s): GITOMER, RALPH J
• Application Number:
  US11/294,488
• Publication Number:
  US 20070087399A1
• Time in Patent Office: 875 Days
• Field of Search: 435/25
• US Class Current: 435/25
• CPC Class Codes: C12Q 1/005 involving specific analytes or enzymes including groups of enzymes, e.g. oxydases; C12Q1/004 takes precedence
• CPC Class Codes: Y10S 435/817 Enzyme or microbe electrode

Abstract

We provide a lactate biosensing strip comprising a working electrode and a reference electrode, the two electrodes being deposited on an electrically insulated base support, the working electrode being formed by immobilizing lactate oxidase and an electron mediator on an inorganic graphite matrix and the graphite layer being deposited on a silver layer of the working electrode and the reference electrode being formed by depositing silver chloride on a silver layer of the reference electrode.

Claims

1. A method for preparing a lactate biosensing strip comprising an electrically insulated base support (1), a pair of isolated first and second silver layers deposited thereon (2), a pair of graphite layers, each one of said pair of graphite layers being deposited on one respective silver layer and electrically connected to said respective silver layer (2), the first silver layer being covered fully by the respective graphite layer, the second silver layer being covered partly in the middle thereof with the respective graphite layer after leaving the terminal and working zone uncovered, a Ag/AgCl electrode (4) provided on top of the working zone of said second silver electrode layer, lactate oxidase deposited with an electron mediator on the working zone of graphite layer covering the first silver layer (5), the silver/silver chloride electrode (4) and enzyme with mediator layer working electrode (5) being supported on said support (1), the working zone of silver/silver chloride reference electrode (4) and working electrode (5) being covered with a hydrophilic membrane, said lactate biosensing strip being disposable, said method comprising:

(a) depositing a pair of silver layers on an electrically insulated base support;

(b) depositing two graphite layers on each of said two silver layers, each of said two silver layers being deposited with one graphite layer, a first graphite layer completely covering the first silver layer, and the second graphite layer covering the second silver layer only in part of the surface thereof that is away from the surface facing the base support;

(c) depositing a silver chloride layer on the second silver layer on the part thereof that is not deposited with a graphite layer to obtain a silver/silver chloride electrode;

(d) adsorbing physically lactate oxidase enzyme with an electron mediator on the first graphite deposited silver layer to obtain a working electrode; and

(e) applying an outer hydrophilic membrane on said first reference electrode and second working electrode to obtain a pair of electrodes on an electrically insulated base support in a single assembly.

2. The method as claimed in claim 1, wherein the electrically insulated base support is polyvinyl chloride.

3. The method as claimed in claim 1, wherein the silver layer is applied by screen-printing.

4. The method as claimed in claim 1, wherein the graphite layer is applied by screen-printing.

5. The method as claimed in claim 1, further comprising testing a sample which is an aqueous lactate solution or blood sample in an amount of 25 to 30 μ

L.

6. The method as claimed in claim 1, wherein the electron mediator is potassium ferricyanide or ferrocene.

7. The method as claimed in claim 1, wherein a working zone of an electrode is a target area used for dispensing an analyte sample.

8. The method as claimed in claim 1, wherein a connecting terminal of the reference electrode is an area used for connecting the reference electrode to an electrometer.

9. The method as claimed in claim 1, wherein the hydrophilic membrane is made of nylon or polyester.

10. A method for preparing a two electrode biosensing strip for measuring lactate, said method comprising:

(a) depositing a pair of silver layers on an electrically insulated base support;

(b) depositing a pair of graphite layers on said silver layers, each of said silver layers being deposited with one graphite layer, a first graphite layer completely covering the first silver layer, and a second graphite layer covering only a part of the second silver layer that is away from the surface facing the base support;

(c) depositing a silver chloride layer on a part of the second silver layer that is not deposited with a graphite layer to obtain a reference electrode;

(d) adsorbing physically lactate oxidase with an electron mediator on the first graphite layer to obtain a working electrode; and

(e) covering said reference electrode and said working electrode with a hydrophilic membrane to obtain said two-electrode biosensing strip in a single assembly.

11. The method as claimed in claim 10, wherein the electrically insulated base support is polyvinyl chloride.

12. The method as claimed in claim 10, wherein each silver layer is applied by screen-printing.

13. The method as claimed in claim 10, wherein each graphite layer is applied by screen-printing.

14. The method as claimed in claim 10, further comprising testing a sample which is an aqueous lactate solution or blood sample in an amount of 25 to 30 μ

L.

15. The method as claimed in claim 10, wherein the electron mediator is potassium ferricyanide or ferrocene.

16. The method as claimed in claim 10, wherein a working zone of an electrode is a target area used for dispensing an analyte sample.

17. The method as claimed in claim 10, wherein a connecting terminal of the reference electrode is an area used for connecting the reference electrode to an electrometer.

18. The method as claimed in claim 10, wherein the hydrophilic membrane is made of nylon or polyester.