Cholesterol sensor containing electrodes, cholesterol dehydrogenase, nicotinamide adenine dinucleotide and oxidized electron mediator

• US 6,214,612 B1
• Filed: 03/03/1997
• Issued: 04/10/2001
• Est. Priority Date: 03/07/1996
• Status: Expired due to Term

• Current Assignee: Panasonic Healthcare Holdings Co., Ltd.
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Iwata, Junko, Yamamoto, Tomohiro, Ikeda, Shin, Yoshioka, Toshihiko, Nankai, Shiro
• Primary Examiner(s): Naff, David M.
• Application Number:
  US08/806,801
• Time in Patent Office: 1,499 Days
• Field of Search: 435/11, 435/25, 435/26, 435/287.1, 435/287.3, 435/817, 204/403
• US Class Current: 435/287.1
• 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

A cholesterol sensor for quantitative determination of cholesterol is provided containing an electrode system and a reaction reagent system. The electrode system contains a measuring electrode such as a carbon electrode and a counter electrode, and the reaction reagent system contains cholesterol dehydrogenase, nicotinamide adenine dinucleotide and an oxidized electron mediator. Electron mediators include ferricyanide, 1,2-naphthoquinone-4-sulfonate, 2,6-dichlorophenol indophenol, dimethylbenzoquinone, 1-methoxy-5-methylphenazinium sulfate, methylene blue, gallocyanine, thionine, phenazine methosulfate and Meldola'"'"'s blue. Diaphorase, cholesterol esterase and a surfactant may also be present. The electrode system is on an insulating base plate, and the base plate has a covering member containing a groove that is a sample supplying channel which extends from an end of the base plate to the electrode system. A reaction layer containing the reagent system in dry form and a layer of a hydrophilic polymer is provided on the base plate or the covering member, or on both the electrode system and covering member so as to be exposed to the sample supplying channel. During operation, the electron mediator is reduced in conjunction with oxidation of cholesterol in a sample by cholesterol dehydrogenase, and an amount of current required to electrochemically re-oxidize the electron mediator is directly proportional to a quantity of cholesterol present in the sample.

Claims

1. A cholesterol sensor comprising an electrode system including a measuring electrode and a counter electrode, and a reaction reagent system, wherein said reaction reagent system contains at least cholesterol dehydrogenase, nicotinamide adenine dinucleotide and an oxidized electron mediator, which is at least one selected from the group consisting of a 1,2-naphthoquinone-4-sulfonate, 1-methoxy-5-methylphenazinium sulfate, Meldola'"'"'s blue, thionine, and dimethyl benzoquinone.

2. A cholesterol sensor comprising an insulating base plate, an electrode system including a measuring electrode and a counter electrode, said electrode system provided on said insulating base plate, and a dry reaction layer provided on or near said electrode system, wherein said reaction layer contains at least cholesterol dehydrogenase, nicotinamide adenine dinucleotide and an oxidized electron mediator, which is at least one selected from the group consisting of a 1,2-naphthoquinone-4-sulfonate, 1-methoxy-5-methylphenazinium sulfate, Meldola'"'"'s blue, thionine, and dimethyl benzoquinone.

3. The cholesterol sensor in accordance with claim 2, wherein said reaction reagent system contains diaphorase.

4. The cholesterol sensor in accordance with claim 2, wherein said reaction reagent system contains cholesterol esterase and a surfactant.

5. A cholesterol sensor comprising an insulating base plate, an electrode system including a measuring electrode and a counter electrode which are provided on said insulating base plate, a covering member having a groove which is placed on said insulating base plate for defining a sample supplying channel which is extended from an end of said base plate to said electrode system, and a reaction layer provided on said base plate or said covering member so as to be exposed to said sample supplying channel and including a reaction reagent system, said reaction reagent system being dry, wherein said reaction reagent system contains at least cholesterol dehydrogenase, nicotinamide adenine dinucleotide and an oxidized electron mediator, which is at least one selected from the group consisting of a 1,2-naphthoquinone-4-sulfonate, 1-methoxy-5-methylphenazinium sulfate, Meldola'"'"'s blue, thionine, and dimethyl benzoquinone.

6. The cholesterol sensor in accordance with claim 5, wherein said reaction layer is divided so as to be provided on both of said electrode system and said covering member.

7. The cholesterol sensor in accordance with claim 5, wherein said reaction layer contains a layer including a hydrophilic polymer in at least part of said reaction layer.

8. The cholesterol sensor in accordance with claim 5, wherein said reaction layer contains a layer including a hydrophilic polymer and an electron mediator in a mixed state, in at least part of said reaction layer.

9. The cholesterol sensor in accordance with claim 5, wherein said measuring electrode comprises carbon.