JPH0519807Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> This invention relates to a diffusion-limiting membrane fixing member in an enzyme electrode, and more specifically, it is suitably used to bring a diffusion-limiting membrane into close contact with the surface of an enzyme electrode. The present invention relates to a diffusion limiting membrane fixing member.

<Conventional technology> Focusing on the characteristic of being able to selectively detect extremely complex organic compounds, proteins, etc. with extremely high sensitivity, bioactive substances are immobilized on the surface of electrodes. Research and development is being carried out to measure the above-mentioned organic compounds, proteins, etc. using enzyme electrodes.

When measuring a target substance using the enzyme electrode described above, it is usually necessary to oxidize the target substance.
Since the concentration of the substance to be measured is measured by performing reduction etc. in the presence of the above-mentioned physiologically active substance and measuring the amount of produced substance or disappeared substance, the upper limit of the measurable concentration is the oxidation, This results in limitations depending on the amount of a substance that causes reduction, such as oxygen, to exist.

Focusing on this point, attempts have been made to increase the measurement limit concentration by attaching a diffusion-limiting membrane to the surface side of the immobilized enzyme membrane on which the physiologically active substance is immobilized, and by limiting the permeation rate of the substance to be measured. .

Specifically, a diffusion-limiting membrane is attached to a cap that is screwed to the base of a rod-shaped enzyme electrode, and when the cap is screwed in, the diffusion-limiting membrane is automatically brought into close contact with the immobilized enzyme membrane. There is.

By adopting such a configuration, the diffusion-limiting membrane can limit the permeation rate of the substance to be measured, making it possible to measure up to a considerably high concentration. In addition, the diffusion-limiting membrane is made removable in order to eliminate the influence of interfering substances contained in the solution to be measured (for example, an increase in the diffusion-limiting effect due to adhesion of interfering substances) and to perform a good measurement. Therefore, a screw-in mechanism using a cap is adopted.

<Problems to be solved by the invention> When the diffusion-limiting membrane fixing member with the above structure is adopted, the diffusion-limiting membrane can be replaced relatively easily. Since the solution to be measured is introduced to the diffusion limiting membrane through the relatively small opening formed, there is a problem in that it is necessary to accurately set the dropping position of the solution to be measured.

To explain in more detail, depending on the material of the diffusion limiting membrane fixing member, there are cases where the material exhibits hydrophilicity and cases where it exhibits water repellency.

If it shows hydrophilicity, not only the surface of the diffusion-limiting membrane fixing member on the side where the solution to be measured is dripped, but also the wall surface of the opening through which the solution to be measured passes through is hydrophilic. When the amount of the target solution is small, there is a problem in that a considerable amount of the target solution diffuses on the upper surface without being guided to the opening, resulting in a decrease in the utilization efficiency of the target solution.

Conversely, when water repellency is exhibited, there is a problem in that the solution to be measured does not fit into the diffusion limiting membrane fixing member, and the possibility of being smoothly guided to the diffusion limiting membrane through the relatively small openings is significantly reduced. .

<Purpose of the invention> This invention was made in view of the above-mentioned problems, and the purpose is to provide a diffusion-limiting membrane fixing member that can smoothly guide the dripped measurement target solution to the diffusion-limiting membrane. There is.

<Means for solving the problem> In order to achieve the above object, the diffusion-limiting membrane fixing member of this invention is a diffusion-limiting membrane fixing member in which a diffusion-limiting membrane is attached in a compressed state to an enzyme electrode on which a physiologically active substance is immobilized. A limiting membrane fixing member having an opening for permeation of a measurement target solution formed at a predetermined position,
The wall surface of the opening is hydrophilic, a predetermined area around the opening on one side of the diffusion-limiting membrane fixing member is water-repellent, and the diffusion-limiting membrane is fixed to the other side. .

However, the above-mentioned diffusion-limiting membrane fixing member may be water-repellent as a whole, and the wall surface of the opening may be treated to make it hydrophilic, or the member may be hydrophilic as a whole. Additionally, the lower surface of the droplet to be measured may be subjected to a water repellent treatment.

Further, it is preferable that the diffusion-limiting membrane fixing member is a flat plate having one end as a gripping portion.

<Function> With the diffusion-limiting membrane fixing member configured as described above, when the diffusion-limiting membrane is attached in a crimped state to the enzyme electrode on which a physiologically active substance is immobilized, the diffusion-limiting membrane is positioned near the opening. When the solution to be measured is dropped onto the membrane fixing member, the solution to be measured is guided to the diffusion limiting membrane through the opening as described below. That is, since the upper surface of the diffusion-limiting membrane fixing member is water-repellent, the solution to be measured does not diffuse at all, and if left as it is, it will continue to remain at the dropping position.
However, since the wall surface of the opening is hydrophilic, diffusion occurs only in this portion, and as a result, all of the dripped solution to be measured is smoothly guided to the diffusion limiting membrane through the opening.

In the case where the diffusion limiting membrane fixing member is water repellent as a whole and the wall surface of the opening is subjected to hydrophilic treatment, or
The same effect as described above can be achieved even when the entire surface is hydrophilic and the lower surface of the droplet to be measured is treated to be water repellent.

Furthermore, if the diffusion-limiting membrane fixing member is a flat plate material with one end as a gripping part, the same effect as above can be achieved, and the diffusion-limiting membrane can be easily attached and removed with one hand. can be done.

<Examples> Hereinafter, examples will be described in detail with reference to the accompanying drawings showing examples.

Fig. 1 is a plan view showing an embodiment of the diffusion-limiting membrane fixing member of this invention, and Fig. 2 is a longitudinal cross-sectional view. A rectangular engagement recess 2 is formed in the center of the long side of the substantially rectangular thin plate 1, and
One short side 3 is formed into an arc shape. A circular opening 4 is formed centered at a position corresponding to the center of the short side 3, and a recess with a radius of curvature equal to the surface of the enzyme electrode 6, which will be described later, is formed over a predetermined range including the opening 4. 41 is formed. Further, a diffusion limiting film 5 is attached to a predetermined position of the thin plate 1 by adhesive or the like so as to cover the opening 4 and the recess 41. Note that the grip portion 11 is located closer to the other short side.

Furthermore, the thin plate 1 having the above structure is made of hydrophilic polyester, and the surface opposite to the side where the recess 41 is formed is treated with fluorine.
Alternatively, water repellency is imparted by applying silicon treatment. However, the range to which water repellency is imparted may be at least a predetermined range centered on the opening 4.

Fig. 3 is a plan view showing the main parts of the biosensor, and Fig. 4 is a longitudinal cross-sectional view. Engaging portions 7 and 8 are provided at opposing positions with 6 in between. More specifically, the engaging portion 7 has an engaging recess 71 whose inner deep portion is formed into an arcuate surface having the same radius of curvature as the short side 3, and the engaging recess 71 71, and a stopper 71a for restricting rotation of the thin plate 1 is provided at a predetermined position near the end of the engagement recess 71. Note that the protrusion 72 may be wide enough to cover the entire width of the engagement recess 71, or
The width may be narrower than the full width of. Also,
The engaging portion 8 has a raised portion 81 having a width approximately equal to the width of the engaging recess 2, and an upper restricting protrusion 82 extending in one direction from the upper portion of the raised portion 81.
The surface of the enzyme electrode 6 is formed into a substantially arcuate surface, and an immobilized enzyme membrane 61 including a selectively permeable membrane is attached thereto.

When attaching a diffusion-limiting membrane to a biosensor having the above configuration, insert the short side 3 of the thin plate 1 into the engagement recess 71 with the diffusion-limiting membrane 5 positioned on the bottom surface (however, in this state , the center of the opening 4 and the center of the enzyme electrode 6 are shifted as shown in FIG. While forcibly bending the thin plate 1, the thin plate 1 is rotated in the direction in which the engaging recess 2 engages with the engaging part 8, and the upper regulating protrusion 82 of the engaging part 8 prevents the thin plate 1 from restoring. By setting the diffusion-limiting membrane 5 in the state shown in FIG. 5B (see FIG. 5B), the diffusion-limiting membrane 5 can be brought into close contact with the enzyme electrode 6 while maintaining an accurate relative positional relationship. To explain in more detail, the enzyme electrode 6
The recess 41 directly faces the immobilized enzyme membrane 61 attached to the surface, and since the recess 41 has the same radius of curvature as the surface of the enzyme electrode 6, Uniform contact force acts,
It is possible to ensure that the diffusion-limiting membrane 5 and the immobilized enzyme membrane 61 are in full contact with each other, and it is also possible to reliably prevent excessive pressure from being applied to any part of the membrane.

In this state, as shown in FIG. It is possible to reliably prevent diffusion in the opening 4.
Since the wall surface of the thin plate itself is hydrophilic in nature, it can be diffused along the wall surface. Therefore, the solution 9 to be measured reaches the diffusion-limiting membrane 5 through the opening 4, and the diffusion of the substance to be measured is restricted, and the solution 9 is guided to the immobilized enzyme membrane 61 with its concentration reduced to a certain extent. Therefore, even if the concentration of the substance to be measured in the solution to be measured is high, the concentration of the substance to be measured can be measured based on a considerably low concentration.

Further, after the measurement is completed, the thin plate 1 can be easily removed by operating the thin plate 1 in the opposite manner to the above-mentioned mounting operation.

In the above embodiment, a case was explained in which a hydrophilic material was used as the thin plate 1, but a water-repellent material was used as the thin plate 1, and the inner surface of the opening 4 was subjected to hydrophilic treatment by corona discharge or the like. Similarly to the above-mentioned embodiment, the measurement target solution 9 dropped onto the thin plate 1 can be smoothly guided to the opening 4, and the spotting can be performed very easily.

Furthermore, in these cases, the edge portion of the opening 4 may be tapered on the side opposite to the recess 41, or the opening 4 itself may be formed in a shape that gradually expands upward.

Further, it is also possible to adopt a configuration in which the diffusion limiting film 5 is attached without forming the recess 41.

Furthermore, the structure of the diffusion-limiting membrane fixing member is not limited to the above embodiment, and as shown in FIG. 6, it may have a cap shape that is removable from the enzyme electrode 6. Even in
Spotting can be done very easily.

<Effects of the device> As described above, this device provides hydrophilicity to the wall surface of the opening of the member in which the aperture for permeation of the solution to be measured is formed, and imparts water repellency to the surface onto which the solution to be measured is dripped. This makes it possible to reliably prevent the dripped solution to be measured from diffusing away from the aperture and to diffuse it intensively towards the aperture, making spotting significantly easier. It has the unique practical effect of being able to.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing an embodiment of the diffusion-limiting membrane fixing member of this invention, Fig. 2 is a longitudinal sectional view, Fig. 3 is a plan view showing the main parts of the biosensor, and Fig. 4 is a longitudinal sectional view. , FIG. 5 is a diagram for explaining the mounting operation, and FIG. 6 is a longitudinal sectional view showing another embodiment. 1... Thin plate, 4... Opening, 5... Diffusion limiting membrane.

Claims (1)

[Claims for Utility Model Registration] 1. A diffusion-limiting membrane fixing member for attaching a diffusion-limiting membrane under pressure to an enzyme electrode on which a physiologically active substance is immobilized, which has an opening at a predetermined position for permeation of a solution to be measured. In addition, the wall surface of the opening is hydrophilic, a predetermined area around the opening on one side of the diffusion-limiting membrane fixing member is water-repellent, and the diffusion-limiting membrane is fixed to the other side. A diffusion-limiting membrane fixing member for an enzyme electrode, characterized in that: 2. Diffusion limiting membrane fixing in the enzyme electrode according to claim 1 of the above-mentioned utility model registration claim, wherein the diffusion limiting membrane fixing member is water repellent as a whole and the wall surface of the opening has been subjected to hydrophilic treatment. Element. 3. Immobilization of the diffusion-limiting membrane in the enzyme electrode according to claim 1 of the above-mentioned utility model registration claim, wherein the diffusion-limiting membrane is hydrophilic as a whole, and the lower surface of the droplet to be measured is treated to be water-repellent. Element. 4. Claim 1 of the above-mentioned utility model registration, in which the diffusion-limiting membrane fixing member is a flat plate material with one end as a gripping part.
A diffusion-limiting membrane fixing member in an enzyme electrode according to any one of items 1 to 3.