JP3451517B2 - Planar type enzyme sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a planar enzyme sensor used as a sensor for detecting a liquid component in a biochemical measuring instrument such as a urine measuring instrument.

[0002]

2. Description of the Related Art A urine meter using this type of planar enzyme sensor is shown in FIG.
An external perspective view of the back side (b)] is available. This urine measuring device 1 detects urine components (urine sugar, etc.) by utilizing the function of an enzyme, and a sensor main body 3 is detachably attached to a measuring device main body 2 and is attached to the front side of the measuring device main body 2. Display unit (LC for displaying measured values (urine sugar, etc.) and various instructions
D) 4 is provided, and a battery cover 5 is provided on the head of the measuring device main body 2.
Is detachably attached. Sensor body 3
Is a sensor holder 6 containing a planar enzyme sensor.
And the sensor cap 7 inserted into the sensor holder 6
Consists of. Further, the measuring device main body 2 has a built-in circuit board on which various electronic components are mounted, a battery, and the like. In such a urine measuring device 1, when urine is applied to the detecting portion (opening) 6a of the sensor holder 6, the measured value is automatically displayed on the display portion 4.

The planar type enzyme sensor has a structure as shown in, for example, FIG. 3 (a cross-sectional view of the detecting portion 6a of the sensor holder 6). The planar enzyme sensor 30 shown here comprises an insulating film 31 as an insulating substrate, a metal electrode 32 made of a thin film of platinum, gold or silver as a hydrogen peroxide electrode, and an immobilized enzyme film 33. Further, the immobilized enzyme film 33 includes a lower protective film 34 and an enzyme film 35.
And an upper protective film 36 and a surface protective film 37.

[0004]

In the planar type enzyme sensor 30 as described above, when a sample (urine) enters from the detecting portion 6a of the sensor holder 6, glucose in the urine is converted into the enzyme of the immobilized enzyme membrane 33. Permeate the membrane 35. By the way, when the electrode interfering substance in the sample permeates to the metal electrode 32 and adheres to the electrode surface, the characteristics are deteriorated. Therefore, the lower protective film 34, which is a polymer film, limits the permeation of the electrode interfering substance in the sample. There is. In addition to the role of limiting the permeation of the electrode interfering substance in the sample, the lower protective film 34 is required to have a function of selectively permeating hydrogen peroxide generated by the enzyme reaction in the enzyme film 35. As the protective film 34, a cellulose film is usually used. However, although a polymer membrane such as a cellulose membrane can selectively permeate hydrogen peroxide, it has a problem that the permeation amount of an electrode interfering substance in a sample cannot be sufficiently limited.

On the other hand, the upper protective film 36 of the immobilized enzyme film 33.
The surface protection film 37 is also made of a polymer film, and its micropores serve to limit the amount of glucose permeated into the enzyme film 35. However, in a normal polymer film, it is difficult to obtain a uniform permeation amount because the size of the micropores varies, and even if an attempt is made to form a dense film to solve this problem, a normal polymer film does not work. , There is a problem.

Therefore, the present invention has been made by paying attention to such problems, and the lower layer related to the hydrogen peroxide electrode limits the permeation of the electrode interfering substance in the sample and the selective permeation of hydrogen peroxide. It is an object of the present invention to provide a planar-type enzyme sensor which is excellent in the above-mentioned property and whose upper layer related to the enzyme film is excellent in uniform glucose permeability.

[0007]

In order to achieve the above object, a planar type enzyme sensor according to claim 1 of the present invention comprises:
A hydrogen peroxide electrode is formed on an insulating substrate, and a polymer film is coated on this hydrogen peroxide electrode and further heated to form
Then , an immobilized enzyme membrane was provided on this polymer membrane , and this immobilized
At least one side of the enzyme membrane was covered with a polymer membrane
The other side of the polycarbonate membrane is the immobilized enzyme membrane side
It is characterized by being provided .

In this enzyme sensor, since the polymer film on the hydrogen peroxide electrode is formed not only by coating but also by heating, the permeation of the electrode interfering substance in the sample is maintained while maintaining the permeability of hydrogen peroxide. Can be sufficiently limited. That is, the performance of the polymer film is further improved by the heat treatment. In particular, by using an ion exchange membrane as the polymer membrane (claim 2 ), better characteristics can be obtained.

Further , in this enzyme sensor, the immobilized enzyme membrane is used.
Polycarbonate coated on at least one side with a polymer film
Carbonate film (hereinafter abbreviated as PC film) is formed
Therefore, the glucose permeation amount becomes uniform. That is, PC film
Has a uniform size of micropores and permeates glucose.
Variation is improved.

[0010] and However, PC film, because it has a very micropores, transmission amount of glucose clogged changes (decreases) easily. In order to prevent this, at least one surface side (upper surface side) of the PC film is covered with a polymer film. In particular, by using a film composed of albumin and glutaraldehyde as the polymer film (claim 4 ), more excellent clogging prevention and glucose permeability are exhibited. That is, it is possible to further improve the function of preventing clogging while maintaining the original performance of the PC film.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on embodiments. A cross-sectional view of the planar type enzyme sensor according to the embodiment is shown in FIG. The planar enzyme sensor 10 shown here is built in the sensor holder 6 of the urine measuring device 1 as shown in FIG. As described above, in the urine measuring device 1, the sensor main body 3 is detachably attached to the measuring device main body 2, and the display unit 4 for displaying the measured value of urine sugar and the like and various instructions on the front side of the measuring device main body 2. Is provided, and the battery cover 5 is detachably attached to the head of the measuring device main body 2. The sensor main body 3 is composed of a sensor holder 6 containing a planar enzyme sensor, and a sensor cap 7 inserted into the sensor holder 6. A calibration switch 8 for calibrating the enzyme sensor is provided on the back side of the measuring device body 2.

This planar type enzyme sensor 10 comprises a polyimide film (PI film) 11 as an insulating substrate.
And a pair of metal electrodes 12 as hydrogen peroxide electrodes and 2
It is composed of a polymer film 13 composed of layers, an immobilized enzyme film 14 composed of two layers, a polymer adhesive film 15, and a polycarbonate film (PC film) 16 covered with a polymer film 17. The insulating substrate may use ceramics or other resin films instead of the PI film 11.

The pair of metal electrodes 12 formed on the PI film 11 catches the increase and decrease of oxygen and hydrogen peroxide due to the enzymatic reaction in the enzyme film 14 as a change in oxidation current. Various metals are used as the electrode, but platinum (Pt) is mainly used as the working electrode, and the reference electrode (counter electrode) is used.
For this, gold (Au), platinum (Pt), silver (Ag), or the like is used.

The polymer film 13 formed on the metal electrode 12 is formed by coating the metal electrode 12 and further heating it. As the polymer material used, a cation exchange membrane is preferable. Among the cation exchange membranes, especially Nafion made by DuPont
(Product name) is most suitable. An ion exchange membrane such as Nafion is superior to a polymer membrane such as a cellulose membrane in suppressing permeation of an electrode interfering substance in a sample and selective permeation of hydrogen peroxide.

The polymer film is coated on the metal electrode 12 and then heat-treated. For example, when nafion is used as the polymer material, about 170 is used.
Heat at 60 ° C for about 60 minutes. This heat treatment further improves the inherent properties of the material as compared with the case of coating alone. The polymer film 13 is composed of two layers in FIG.
There is no limit to the number of layers. However, as the film thickness of the polymer film 13 is larger, the permeation of the electrode interfering substance in the sample can be more restricted. Therefore, regardless of the number of layers, whether it is one layer or a plurality of layers, the total thickness of the enzyme sensor is taken into consideration. It is preferable to increase the thickness.

The immobilized enzyme membrane 14 formed on the polymer membrane 13 may be an ordinary one, such as a cross-linking method using a cross-linking material having a functional group, an encapsulation method in which a gel lattice or a polymer is coated. Is formed using. For example, when glucose oxidase is used as the enzyme, the enzymatic reaction is Glucose + O ₂ → gluconic acid + H ₂ O ₂ , and oxygen (O ₂ ) is consumed (decreased) with the decomposition of glucose, resulting in excess. Hydrogen oxide (H ₂ O ₂ ) is generated (increased) and gluconic acid is generated (pH decreased).
Although the immobilized enzyme membrane 14 is also composed of two layers in FIG. 1,
This may also be increased or decreased as appropriate.

PC film 1 provided on the immobilized enzyme film 14
6 is fixed to the enzyme film 14 by a polymer adhesive film 15. One side (upper surface side) and the other surface side (lower surface side) of the PC film 16, that is, the entire peripheral surface is covered with the polymer film 17. As a material for the polymer film 17, there is a protein immobilization film or the like, but it is preferable to form it by using albumin and glutaraldehyde. Albumin is effective for the wet diffusion of urine components and the permeation of glucose, while preventing the clogging of the uniformly sized micropores which is a characteristic of the PC membrane 16, while utilizing the original characteristics of the PC membrane 16. It can prevent clogging.

Further, by using the polymer film 17 such as albumin, the sensitivity test of the enzyme sensor can be conducted.
That is, since the polymer film 17 can prevent dust from adhering to the PC film 16, the sensitivity of the enzyme sensor is checked, and then the enzyme sensor is shipped in a dry state. It can be used with high sensitivity, and all the enzyme sensors can be checked, increasing reliability. The PC membrane 16 covered with the polymer membrane 17 is the immobilized enzyme membrane 1 with the adhesive membrane 15 made of the same material as the polymer membrane 17 (eg albumin).
It is in close contact with 4. The polymer film 17 may be provided only on the upper surface side of the PC film 16, but by providing it on the lower surface side, not only the formation of the polymer film 17 is facilitated but also the adhesive film is used. Therefore, it is possible to reduce the number of materials and processes.

A thin and uniform film can be obtained by using a dip coating method or a spin coating method for forming each of the above films.

[0020]

As described above, according to the planar type enzyme sensor of claim 1, since the polymer film on the hydrogen peroxide electrode is formed not only by coating but also by heating, the peroxide It is possible to sufficiently limit the permeation of the electrode interfering substance in the sample while maintaining the hydrogen permeability. That is, the performance of the polymer film is further improved by the heat treatment. In particular, by using an ion exchange membrane as the polymer membrane (claim 2 ), better characteristics can be obtained.

Also, a polycarbonate membrane (PC) having at least one surface side coated with a polymer membrane on an immobilized enzyme membrane
Since the membrane is provided, not only the glucose permeation amount becomes uniform, but also the clogging of the PC membrane can be prevented.
Further, since the polymer film can prevent dust and the like from adhering to the PC film, all the enzyme sensors can be checked and the reliability of the enzyme sensors is enhanced.

In particular, as a polymer film covering the PC film,
By using a membrane composed of albumin and glutaraldehyde (claim 4 ), even better prevention of clogging and glucose permeability will be exhibited. That is,
It is possible to further improve the function of preventing clogging while maintaining the original performance of the PC film.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a detection unit in a state where a planar enzyme sensor according to an embodiment is built in a sensor holder.

FIG. 2 is a front perspective view (a) and a rear perspective view (b) of a urine measuring instrument using a planar enzyme sensor.

FIG. 3 is a transverse cross-sectional view of a detection unit in a state where a planar type enzyme sensor according to a conventional example is built in a sensor holder.

[Explanation of symbols]

1 urine meter 6 Measuring instrument body 11 PI film (insulating substrate) 12 Metal electrode (hydrogen peroxide electrode) 13 Polymer membrane 14 Immobilized enzyme membrane 15 Polymer adhesive film 16 Polycarbonate film 17 Polymer membrane

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takahide Tanaka               24, Yamanouchi-Yamanoshitamachi, Ukyo-ku, Kyoto               Omron Life Science Research Institute               Within (72) Inventor Hideki Endo               24, Yamanouchi-Yamanoshitamachi, Ukyo-ku, Kyoto               Omron Life Science Research Institute               Within (72) Inventor Misako Inoue               24, Yamanouchi-Yamanoshitamachi, Ukyo-ku, Kyoto               Omron Life Science Research Institute               Within (72) Inventor Yusaku Sakoda               24, Yamanouchi-Yamanoshitamachi, Ukyo-ku, Kyoto               Omron Life Science Research Institute               Within                (56) Reference JP-A-4-194661 (JP, A)                 JP 62-261952 (JP, A)

Claims (4)

(57) [Claims] 1. A hydrogen peroxide electrode is formed on an insulating substrate , and a polymer film is coated on the hydrogen peroxide electrode.
It is formed by heating, and an immobilized enzyme membrane is provided on this polymer membrane.On this immobilized enzyme membrane, a polycarbonate membrane coated with a polymer membrane on at least one side is immobilized enzyme membrane side on the other side. A planar-type enzyme sensor characterized by being provided as. 2. The polymer membrane coating the hydrogen peroxide electrode is an ion exchange membrane.
1 Symbol placement planar type enzyme sensor. Wherein the polycarbonate membrane is planar type enzyme sensor according to claim 1, wherein the other surface side is coated with a polymer film. 4. A polymer film covering the polycarbonate film, planar-type enzyme sensor according to claim 1 or claim 3, wherein the consisting of albumin and glutaraldehyde.