JPS612060A - Biosensor - Google Patents

Abstract

PURPOSE:To obtain a sensor having high detecting sensitivity and high response speed by providing a filter for removing disturbance for measurement having about 5-15mum pore size to a working electrode. CONSTITUTION:A spacer 1 consisting of a soft material, etc. is sandwiched by substrates 2 and 3 and a hole 1a is provided to the center of the spacer 1. Holes 2a to be used as an inlet and outlet for a soln. to be measured are provided to both ends of the substrate 2 and a plate-shaped counter electrode 2c consisting of platinum, etc. is fixed to the inside flank of the substrate 2. The working electrode 3a fixed with enzyme such as glucose oxidase or a physiologically active material such as miroorganisms by means of a crosslinking agent such as albumin to the plate-shaped electrode body consisting of platinum, etc. is fixed to the inside flank of the substrate 3 in such a manner that the surface fixed with the physiologically active material faces the inside. The filter 5 consisting of a porous material such as polycarbonate having the pore size within a 5- 15mum range is provided to the surface of the electrode 3a. The disturbance of the measurement by a disturbing material is thus obviated and the detecting sensitivity and response speed are increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a biosensor equipped with a filter.

[Background technology]

Some biosensors include a working electrode in which a physiologically active substance is fixed to a conductive substrate (electrode body) and a counter electrode.

When using such a biosensor, it is necessary to protect the biosensor from interference from various components (matrix) other than the substance to be measured in the sample solution. However, such protective measures must not reduce detection sensitivity or slow response speed.

[Purpose of the invention]

This invention was made in view of these circumstances,
The aim is to provide a biosensor with high detection sensitivity and fast response speed.

[Disclosure of the invention]

To prevent the biosensor from being affected by the interfering substances, it is preferable to attach a filter for removing interfering substances to the biosensor so that the substance to be measured passes through but the substances interfering with the measurement do not pass through.

However, the detection sensitivity of the biosensor must not be lowered and the response speed must not be slowed down due to the attachment of the interfering substance removal filter.

Therefore, in order to achieve the above object by improving the filter, the inventors first investigated the reason why the detection sensitivity and response speed of a biosensor equipped with the filter become low. As a result, we found that it is important to make the pore size of the filter appropriate. In other words, if the pore diameter of the filter is as small as 0.1 to 1 μm, it will be difficult for the substance to be measured to pass through the filter, so it needs to be made larger, but if it is too large, the filter will not be effective. It is.

The inventors have further investigated the range of pore diameters that allow the substance to be measured to pass through easily, while preventing interfering substances from passing through. As a result, we found the following.

In other words, interfering substances include relatively small proteins and relatively large blood cells such as red blood cells, but physiologically active substances are usually fixed to the electrode body by a cross-linking agent, so the network structure created by the cross-linking agent This prevents proteins etc. from passing through.

Therefore, it has been found that it is not necessarily necessary to use a filter with a small pore size that does not allow passage of proteins, etc., but it is sufficient to use a filter with a pore size that does not allow blood cells to pass through. It was also found that the pore diameter through which the substance to be measured can easily pass, but through which blood cells and the like have difficulty, is 5 to 15 μm. Based on these findings, the inventors discovered that if a filter with a pore size of 5 to 15 μm is attached to at least the working electrode, the detection sensitivity of the biosensor increases and the response speed increases. This invention was completed here.

Therefore, the present invention includes a working electrode to which a physiologically active substance is immobilized and a counter electrode thereof, and at least the working electrode is provided with a filter for removing measurement interfering substances, and the pore size of the interfering substance removing filter is 5 to 15 μm. The gist is a biosensor with certain characteristics. The present invention will be explained in detail below.

FIG. 1 and FIG. 2 show an embodiment of the biosensor according to the present invention.

In the biosensor shown in FIG. 1, a spacer l made of a soft material or the like is sandwiched between substrates 2.3.

A horizontally long hole 1a is provided in the center of the spacer l.

One hole 2a is provided on each side of the substrate 2 to serve as an inlet/outlet for a solution to be measured. A cylindrical protrusion 2b is provided at the outer end of the hole 2a, and a tube 4 is connected to the protrusion 2b.A plate-shaped counter electrode 2C made of platinum or the like is provided on the inner surface of the substrate 2. Fixed - On the inner surface of the substrate 3, a plate-shaped electrode body made of platinum or the like is fixed with an enzyme such as glucose oxidase, a physiologically active substance such as a microorganism, or a crosslinking agent such as albumin or glutaraldehyde. A working electrode 3a is fixed with the physiologically active substance fixing surface facing inward, and the surface of the working electrode 3a is made of a porous material such as polycarbonate and has a pore diameter of 5 to 15 μm (preferably 8 μm). A filter 5 having a diameter of 12 μml is provided.The space created by covering the upper and lower surfaces of the hole 1a of the spacer with the substrate 3.4 becomes a passage 6 through which the solution to be measured flows. Both ends are connected to holes 2a and 2a of the substrate 2, respectively.

In the biosensor shown in FIG. 2, a filter 7 having a pore diameter in the range D of 5-15 pm (preferably 8-12 μm) is also provided on the surface of the counter electrode 2c. The only difference is that it has the same structure as the one in Figure 1. In the figure, the same percentage as in FIG. 1 indicates the same thing.

The biosensor according to this invention has a pore diameter of 5 to 15 μm.
(preferably 8 to 12 μm) is provided on the working electrode, so the substance to be measured can easily pass through the filter and actively react with the physiologically active substance. Relatively large interfering substances, such as blood cells, have difficulty passing through the filter. Furthermore, relatively small interfering substances such as proteins are prevented from reaching the electrode body by the network structure created by the crosslinking agent. Therefore, the measurement is not interfered with by interfering substances, and the detection sensitivity is high.
The response speed is also fast.

In addition, as in the biosensor shown in Figure 2, the counter electrode also has a pore diameter of 5 to 15 μm (preferably 8 to 12 μm).
) If a filter is provided within the range of ), the detection sensitivity of the biosensor will be further prevented from decreasing because it will prevent relatively large interfering substances from adhering to the counter electrode.

Next, Examples and Comparative Examples will be described.

The biosensor with the configuration shown in FIG. 1 was provided with filters of the types and pore sizes shown in Table 1 to form the biosensors of Examples 1 to 3 and Comparative Example 1, and the biosensor e with the configuration shown in FIG. , the biosensor of Example 4.5 was provided with a filter of the type and pore size shown in Table 1, and the biosensor of Comparative Example 2 was the biosensor of FIG. 1 with no filter. did. However, in both cases, an electrode with glucose oxidase immobilized on a platinum plate (COD-immobilized electrode) with a crosslinking agent consisting of albumin and glutaraldehyde was used as the working electrode, and an electrode made of platinum was used as the counter electrode.

(Left below) 1. Using the biosensors of Examples 1 to 3 of Table 11 and Comparative Example 1,
Samples containing glucose were measured, and response speed and detection sensitivity were measured. The results are shown in Table 2.

(Margin below) Table 2 From Table 2, the biosensors of Examples 1 to 3 are the same as those of Comparative Example 1.
It can be seen that the response speed is faster and the detection sensitivity is higher than that of the previous one.

Using the biosensors of Examples 1 to 5 and Comparative Example 2,
The glucose concentration in blood (whole blood) was analyzed 100 times in succession to measure the rate of decrease in sensitivity of the biosensor. The results are shown in Table 2.

From Table 2, the biosensors of Examples 1 to 5 have lower sensitivity reduction rates than those of Comparative Example 2, and the biosensors of Examples 1 to
When biosensors equipped with filters of the same pore size are compared among 5, that is, Example 1 and Example 4. Example 2
When comparing Example 5 and Example 5, it was found that the counter electrode also had a pore diameter of 5 to
It can be seen that Examples 4 and 5, in which a filter within the range of 15 μm was provided, had smaller sensitivity reduction rates than Examples 1 and 2, in which such a filter was not provided on the opposite electrode. .

〔Effect of the invention〕

Since the biosensor according to the present invention is provided with a filter for removing interfering substances at least on the working electrode and has a pore diameter of 5 to 15 μm, the biosensor has high detection sensitivity and fast response speed.

[Brief explanation of drawings]

1 and 2 are longitudinal cross-sectional views of a biosensor according to the present invention, respectively. 2c...Counter electrode 3a...Working electrode 5, 7...filter agent for removing interfering substances Patent attorney Takehiko Matsumoto Figure 1 Figure 2 Procedure amendment (view 1, case display date m59'f) '*i'FM 123987 No. 2, name of the invention Biosensor 3, relationship with the case of the person making the amendment Patent applicant Location 1048 Kadoma, Kadoma City, Osaka Name (583) Matsushita Electric Works Co., Ltd. Representative 4 Um Teiyaku Iku Kobayashi 4, Agent 6, Specification to be amended 7, Contents of amendment (11 Specification, page 3, line 16, ``Is hindered.'' and 1
Between "therefore," in line 7, there is no possibility that detection sensitivity will decrease due to adsorption of proteins to the physiologically active substance immobilized on the electrode. However, since blood cells and the like pass through the network structure, a decrease in sensitivity is observed due to their adsorption. (2) On page 5, line 15 of the specification, “Substrate 3,
4" should be corrected to read "Substrates 2 and 3."

Claims (1)

[Claims] (1) A working electrode to which a physiologically active substance is immobilized and a counter electrode are provided, and at least the working electrode is provided with a filter for removing measurement interfering substances, and the pore size of the interfering substance removing filter is 5 to 15 μm. Characteristic biosensor.