JP6134615B2 - Absorption pad - Google Patents

Description

  The present invention relates to an absorption pad, and more particularly to an absorption pad suitable for a test kit using an immunochromatography method.

  There is an immunochromatography method as a method for easily examining various diseases using a body fluid such as blood, serum, or pharyngeal wipe as a specimen. The immunochromatography test kit using this method mainly consists of a chromatographic medium (membrane), a sample dropping part (sample pad), a labeling reagent holding part (conjugate pad), and an absorption part (absorption pad). In this method, various diseases are examined using antigen-antibody reaction.

  As the absorbent pad, generally used are nonwoven fabrics of cotton and glass fibers, nonwoven fabrics such as superabsorbent fibers, nonwoven fabrics using fibers in which superabsorbent polymer particles are contained in hydrophilic fibers, and the like.

JP 2009-63482 A JP 2012-189346 A

  In the examination by the above immunochromatography method, it has been conventionally required to determine a disease quickly and accurately. In order to make the determination quickly and accurately, it is necessary to shorten the analysis time and to eliminate the ambiguity of the determination due to blurring of the determination portion of the chromatographic medium.

  In response to such a demand, an absorbent pad made of cotton or glass fiber non-woven fabric has liquid return after liquid absorption, which causes ambiguity in judgment due to bleeding of the judgment section, and does not necessarily satisfy the above demand. It was.

  In addition, the absorption pad containing the superabsorbent fiber has a low absorption rate of the liquid sample, and the liquid sample is not sufficiently absorbed by the absorption pad within a prescribed reaction time (about 10 to 15 minutes). For this reason, there is a problem that a positive signal appearing in the determination part is blotted by an excessive liquid sample remaining on the chromatographic medium, or a background signal is increased because a colored labeling substance is not sufficiently collected. .

  In addition, in order to increase the absorption rate of a liquid sample, it has been studied to use an absorption pad in which superabsorbent polymer particles are sprayed on cellulose fibers or pulp fibers. However, in the case of such an absorbent pad, it is difficult to make the fiber density uniform and the spray amount uniform, and the water absorption speed tends to vary between products, so it is difficult to obtain stable performance.

  Then, this invention aims at provision of the absorption pad which can perform the determination of the disease rapidly and correctly using the test kit by an immunochromatography method.

  The present invention realizes shortening of the analysis time of the immunochromatography method and accurate determination of the disease by using the sponge body of the integral structure having hydrophilicity for the absorption pad which is a component of the immunochromatography test kit. It is. The monolithic sponge body is a single structure body in which continuous pores having a uniform and fine pore diameter are formed, and is a resin porous body that absorbs liquid in the continuous pores.

  Since a sponge body in which continuous pores having a uniform and fine pore diameter are formed is used for the absorption pad, the absorption rate of the liquid sample is increased by capillary action, and the liquid sample is difficult to return from the sponge body. .

The smaller the average pore diameter of the sponge body, the faster the water absorption speed of the liquid sample due to the capillary phenomenon is promoted, and the liquid sample is less likely to return. Therefore, the average pore diameter of the sponge body is 10 by pressing as described later. It is preferable that the thickness is reduced to μm or less.

  Accordingly, it is possible to quickly and accurately determine a disease using an immunochromatographic test kit.

  In addition, since the absorbent pad is a monolithic sponge body having no fibers, the manufacturing environment is not deteriorated due to the dropping of the fibers, and the manufacturing environment of the test kit can be kept clean.

  The water retention capacity of the sponge body is preferably 70% or more, and the water absorption speed of the sponge body is preferably 2.0 mg / min or more.

  If the porosity of the sponge body is lower than 40%, the amount of liquid sample that can be absorbed (water retention rate) is remarkably reduced, and if it exceeds 95%, the practical strength is poor, so the porosity of the sponge body is 40% or more. 95% or less is suitable.

  The sponge body may be a polyvinyl acetal resin porous body having vinyl alcohol in the molecular chain.

  A nonionic surfactant may be used as a hydrophilizing agent for enhancing the hydrophilicity of the sponge body. The nonionic surfactant may be added to the raw material for producing the sponge body, or may be attached to the produced sponge body by spraying or the like. Alternatively, the nonionic surfactant may be adhered to the sponge body by immersing the produced sponge body in a nonionic surfactant solution (chemical solution).

  A sponge body may be generated by a pore-generating agent extraction method. By using the pore-generating agent extraction method, variation in pore diameter can be suppressed.

  The sponge body may be pressed to reduce the thickness of the sponge body. By pressing and reducing the thickness of the sponge body, the expansion ratio of the sponge body can be increased, and the effect of preventing reversion can be enhanced. The press rate (volume change rate before and after pressing) is preferably 75% or less (the volume after pressing is 75% or less of the volume before pressing).

  According to the present invention, it is possible to quickly and accurately determine a disease using an immunochromatographic test kit.

It is a figure which shows the test | inspection kit which concerns on one Embodiment of this invention, (a) is a top view, (b) is a side view. It is a contrast table which shows the measurement result of the water absorption performance of each absorption pad, water retention performance, a pore diameter, and a porosity.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a test kit (a test kit for immunochromatography) 1 according to this embodiment includes a chromatographic medium (membrane) 2 as a detection member, a sample pad (sample dropping part) 3 as a sampling member, and a label A reagent holding member (conjugate pad) 4, an absorption pad 5 as an absorption member, and a base 6 as a support member are provided. The test kit 1 is used in an immunochromatography method in which body fluids such as blood, serum, and pharyngeal wiping fluid are used as specimens, and various diseases are easily examined using an antigen-antibody reaction.

  The test kit 1 is a rectangular thin plate as a whole, and is configured by adhering a chromatographic medium 2, a sample pad 3, a reagent holding member 4, and an absorption pad 5 to the upper surface of a base 6. The base 6 has a thin plate shape, and the chromatographic medium 2 overlaps the upper surface of the central portion of the base 6 in the longitudinal direction. The base 6 is not particularly limited as long as it is a liquid-impermeable material such as polyethylene terephthalate, and can be appropriately selected according to the application.

  The sample pad 3 overlaps the upper surface of the base 6 on the upstream side (right side in FIG. 1) in the liquid sample development direction (movement direction). The sample pad 3 may have a structure that does not protrude from the tip of the base 6 (the right end in FIG. 1), or a structure that protrudes. The sample pad 3 is a nonwoven fabric containing pulp, for example.

  In detection of a substance to be detected in a liquid sample using the detection kit 1, a liquid sample is dropped on the sample pad 3 or a body fluid (for example, tear fluid, blood, etc.) is directly brought into contact with the sample pad 3. A liquid sample is collected. The liquid sample absorbed by the sample pad 3 moves to the downstream side (left side in FIG. 1) in the developing direction by a capillary phenomenon, and further moves to the labeling reagent holding member 4 by the capillary phenomenon.

  The labeling reagent holding member 4 overlaps the upper surface of the base 6 between the chromatographic medium 2 and the sample pad 3. The downstream end of the labeling reagent holding member 4 overlaps the upper surface of the upstream end of the chromatographic medium 2, and the downstream end of the sample pad 3 overlaps the upper surface of the labeling reagent holding member 4.

  The labeling reagent holding member 4 holds, for example, a labeling reagent in which an antibody that specifically binds to a substance to be detected is labeled with a gold colloid. The labeling reagent is eluted in the liquid sample that has moved from the sample pad 3 by capillary action, and binds to the substance to be detected in the liquid sample in the process of moving the liquid sample further downstream to form a conjugate.

  The labeling reagent is not particularly limited as long as it specifically binds to the substance to be detected, but no special device is required to determine the presence or absence of the substance to be detected, and red coloring can be easily confirmed visually. Since it can do, it is preferable that it is labeled with colloidal gold.

  The chromatographic medium 2 is composed of a porous chromatography member (for example, a nitrocellulose film or a cellulose acetate film). A detection reagent that specifically binds to the substance to be detected (for example, the same antibody as that of the labeling reagent) is immobilized on the chromatographic medium 2. The detection reagent is fixed in the form of a line perpendicular to the longitudinal direction of the detection kit 1 in the detection reagent fixing part 7 on the chromatographic medium 2, and the detection reagent fixing part 7 is captured by capturing the conjugate. A red line will appear. By visually confirming this line, it can be determined that the substance to be detected is present in the liquid sample.

  Further, a control reagent that specifically binds to the labeling reagent (for example, an antibody that recognizes an antibody possessed by the labeling reagent) is immobilized on the chromatographic medium 2. The control reagent is fixed in a line perpendicular to the longitudinal direction of the detection kit 1 in the control reagent fixing unit 8. The control reagent fixing unit 8 is located on the downstream side of the detection reagent fixing unit 7 on the chromatographic medium 2.

  When the control reagent captures the labeling reagent, a red line appears in the control reagent fixing portion 8. By visually confirming this line, it can be seen that the liquid sample has moved to the control reagent fixing part 8, and it can be determined that the liquid sample has passed through the detection reagent fixing part 7.

  The absorbent pad 5 is composed of a sponge body having a hydrophilic structure. The monolithic sponge body is a single structure body in which continuous pores having uniform and fine pore diameters are formed, and is a resin porous body that expands by absorbing liquid in the continuous pores.

  Thus, since the sponge body in which continuous pores having a uniform and fine pore diameter are formed is used for the absorption pad 5, the absorption rate of the liquid sample is increased by capillary action. Further, since the sponge body expands when the liquid sample is absorbed, the liquid sample is unlikely to return from the absorption pad 5 to the chromatographic medium 2, and the determination part (detection reagent fixing part 7 and control reagent fixing part 8) is blotted by the return liquid. Is suppressed, and accurate determination becomes possible.

  Therefore, the determination of the disease using the test kit 1 can be performed quickly and accurately.

  In addition, since the absorbent pad 5 is an integral structure sponge body that does not have fibers, the manufacturing environment due to fiber dropping does not deteriorate, and the manufacturing environment of the test kit 1 can be maintained clean.

  The sponge body of the present embodiment is made of a polyvinyl acetal resin porous material (PVAt resin porous material) having vinyl alcohol in the molecular chain and excellent in water absorption and water retention.

  The PVAt porous resin material is, for example, a mixture of one or more polyvinyl alcohols (raw materials) having an average polymerization degree of 500 to 3000 and a saponification degree of 80% or more to form an aqueous solution. Mineral acids and starch as a pore-generating agent are added, and these mixed solutions are poured into a predetermined mold, reacted at 40 to 80 ° C. and taken out from the mold, and then the pore-generating agent and the like are removed by washing with water. Can be obtained. Thus, since the PVAt-based resin porous material is generated using the pore generating agent extraction method in which continuous pores are formed by extraction of the pore generating agent, variations in the pore diameter can be suppressed.

  In addition, the absorbent pad 5 is obtained by slicing a block of a dry PVAt-based resin porous material to a predetermined thickness, and the obtained thin plate-shaped PVAt-based resin porous material has a predetermined size and shape by die cutting or the like It is manufactured by processing.

  A nonionic surfactant may be used as a hydrophilizing agent that increases the hydrophilicity of the PVAt-based resin porous material. The nonionic surfactant may be added to the raw material for producing the PVAt resin porous material (previously contained in polyvinyl alcohol as a raw material), and adhered to the produced PVAt resin porous material by spraying or the like. You may let them. Moreover, the nonionic surfactant may be attached to the PVAt resin porous material by immersing the produced PVAt resin porous material in a nonionic surfactant solution (chemical solution).

  As the PVAt-based resin porous material, those having a porosity of 40% to 95% and an average pore diameter of 20 μm or less are preferable.

  If the porosity is less than 40%, the amount of the absorbable liquid sample (water retention rate) is remarkably reduced, and if the porosity exceeds 95%, the practical strength is poor and none is suitable for this application. . Further, when the average pore diameter exceeds 20 μm, the increase in the water absorption speed of the liquid sample due to the capillary phenomenon is slowed down, and the liquid sample is easily returned.

  The porosity is measured with a dry automatic densimeter by measuring the true volume of a dry rectangular parallelepiped PVAt-based resin porous material sufficiently dried by a drier. From the apparent volume and true volume of the rectangular parallelepiped, the following formula is obtained: This is the value calculated in (1).

  Porosity (%) = (apparent volume−true volume) / apparent volume × 100 (1)

  The average pore diameter is an average value of the diameters of a plurality of pores present in the internal structure of the PVAt-based resin porous material. In the present embodiment, the pore diameter corresponding to the mode of the distribution is defined as the average pore diameter in the pore diameter distribution curve measured by a mercury porosimeter (manufactured by Yuasa Ionics Co., Ltd., Autoscan-33). .

  As the PVAt-based resin porous material, a material having a water absorption speed of 2.0 mg / min or more and a water holding power of 70% or more is preferable. This is because, when the water absorption rate is less than 2.0 mg / min or when the water retention capacity is less than 70%, it is difficult to quickly and accurately determine the disease. In addition, the measuring method of a water absorption speed | rate and a water retention capacity is mentioned later.

  Further, the PVAt-based resin porous material may be pressed and the sponge body may be reduced in thickness by pressing from the thickness direction. By pressing the PVAt-based resin porous material to reduce the thickness, the expansion ratio of the PVAt-based resin porous material can be increased, and the effect of preventing reversion can be enhanced. The press rate (volume change rate before and after pressing) is preferably 75% or less (the volume after pressing is 75% or less of the volume before pressing).

  Further, as the sponge body, a resin other than the PVAt resin porous material may be used.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not limited to a following example.

(Water absorption performance)
As shown in the comparison table of FIG. 2, Examples 1 and 2 and Comparative Examples 1 to 5 according to the present invention are prepared as an absorption pad, and members other than the absorption pad (chromatographic medium, sample pad, labeling reagent) A test kit as shown in FIG. 1 was prepared by using a common member as a holding member and a base, and changing only the absorption pad. The width D of the test kit is 5 mm, the total length of the test kit (the total length of the base 6) L1 is 70 mm, the total length L2 of the chromatographic medium 2 is 35 mm, the total length L3 of the sample pad 3 is 20 mm, and the total length of the labeling reagent holding member 4 L4 is 10 mm, the total length L5 of the absorption pad 5 is 25 mm, the length L6 of the overlapping range between the labeling reagent holding member 4 and the chromatographic medium 2 is 5 mm, and the length L7 of the overlapping range between the absorbing pad 5 and the chromatographic medium 2 Is 5 mm.

Examples 1 and 2 are both PVAt-based resin porous materials having an average pore diameter of 20 μm or less. Example 1 is obtained by pressing Example 2 (Example 2 is obtained by omitting the press process of Example 1), and Example 1 and Example 2 except for the presence or absence of a press. Are the same. Since the average pore diameter of Example 1 is 7.48 μm (10 μm or less) and the average pore diameter of Example 2 is 13.38 μm , the average pore diameter of Example 1 is that of Example 2 by pressing. It can be seen that it is smaller than the average pore diameter (0.56 times that of Example 2).

  Comparative Example 1 is a PVAt-based resin porous material having an average pore diameter exceeding 20 μm. The average pore diameter of Comparative Example 1 is 63.67 μm, which is about 8.5 times that of Example 1 and about 4.8 times that of Example 2.

  Comparative Example 2 is a cellulosic fiber material filter paper, Comparative Example 3 is the same cellulosic fiber material as Comparative Example 2, and Comparative Examples 4 and 5 are both glass fiber materials.

  The water absorption rate is the weight reached by the absorbent pad per unit time (1 minute) of the dedicated extract dropped in a predetermined amount (100 μL) on the sample pad of the sample kit. Even if the members other than the absorbent pad are the same, the water absorption speed varies depending on the performance of the absorbent pad. Therefore, the water absorption performance of the absorbent pad (long or short judgment time) can be evaluated by the water absorption speed, and the water absorption speed is fast ( The faster the determination is possible, the higher the weight reached per unit time).

  In measuring the water absorption rate, 100 μL (microliter) of the test sample extract was dropped on the sample pad for each of the sample kits, and when 10 minutes had passed since the dropping, the absorbent pad was removed from the base and weighed (before drying). Weight) A1 was measured, and after the absorbent pad was dried in a dryer at a temperature of 60 ° C. for 12 hours, the weight (weight after drying) A2 was measured.

  From the weight A1 before drying, the weight A2 after drying, and the development time (10 minutes), the absorption rate (mg / min) was calculated by the following formula (2).

  Absorption rate = (weight before drying A1−weight after drying A2) / development time (2)

  The measurement results of the weight A1 before drying and the weight A2 after drying and the calculation result of the water absorption rate of each example and comparative example are shown in the comparison table of FIG. As is clear from FIG. 2, the water absorption rate of Example 1 is faster than Comparative Example 4 where the water absorption rate is the fastest among the comparative examples, and the water absorption performance of Example 1 is superior to any of the comparative examples. I understand. Moreover, the water absorption speed of Example 2 is equivalent to Comparative Examples 2 and 3 whose water absorption speed is relatively fast, and it can be seen that Example 2 also has excellent water absorption performance. Moreover, the water absorption speed | velocity | rate of Comparative Examples 1 and 5 is remarkably slower than Example 2, and it turns out that water absorption performance is worse than Example 2. FIG. Moreover, since the water absorption rate of Example 1 is 2.210 mg / min and the water absorption rate of Example 2 is 1.170 mg / min, the water absorption rate of Example 1 is about twice that of Example 2. You can see that it is faster. That is, it can be seen that when the average pore diameter is reduced by half by press working, the water absorption speed is increased approximately twice.

(Water retention performance)
The water retention capacity is the weight percent of the liquid contained in the liquid that does not flow out to the outside after being left for a predetermined time, and remains inside. ) Can be evaluated, and the higher the water retention capacity (%), the more difficult it is for the liquid to return, and an accurate determination becomes possible.

  In the measurement of water retention capacity, samples of a predetermined shape (vertical 20 mm × horizontal 20 mm × predetermined thickness) were prepared for each of Examples 1 and 2 and Comparative Examples 1 to 5, and the weight (dry weight) W1 of the prepared sample. The sample was submerged in water at a temperature of 20 ° C., evacuated for 10 minutes to allow water to penetrate into the inside, and then the sample was pulled out of the water and the weight (pre-standing weight) W2 was measured. Next, the sample was submerged again in water at a temperature of 20 ° C., vacuumed for 10 minutes to allow water to penetrate into the interior, and then the sample was pulled out of the water and placed on filter paper (No. 5B for quantitative analysis, manufactured by Advantech). After standing for a predetermined time (5 minutes), the weight (weight after standing) W3 was measured.

  The initial water absorption B1 is calculated from the dry weight W1 and the weight before standing W2 by the following formula (3), and the water absorption after standing by the following formula (4) is calculated from the dry weight W1 and the weight W3 after standing. The amount B2 was calculated, and the water retention capacity was calculated by the following equation (5) from the initial water absorption amount B1 and the water absorption amount B2 after standing.

Initial water absorption B1 = weight before standing W2−dry weight W1 (3)
Water absorption after standing B2 = weight after standing W3-dry weight W1 (4)
Water retention (%) = Water absorption after standing B2 / Water absorption before standing B1 × 100 (5)

  The comparison table of FIG. 2 shows the water absorption amount B1 before standing and the water absorption amount B2 after standing and the water retention capacity of each example and comparative example. As can be seen from FIG. 2, the water retention capacity of Examples 1 and 2 is significantly higher than those of Comparative Examples 1 to 5, and the water retention performance is extremely excellent. Moreover, when Example 1 and Example 2 are compared, it turns out that water retention power increases by press work.

  In addition, this invention is not limited to the above-mentioned embodiment described as an example, and its Example, In the range which does not deviate from the technical idea which concerns on this invention even if it is other than the above-mentioned embodiment etc. If so, various changes can be made according to the design and the like.

DESCRIPTION OF SYMBOLS 1 ... Detection kit, 2 ... Chromatographic medium (detection member, membrane), 3 ... Sample pad (collection member, sample dripping part), 4 ... Labeling reagent holding member (conjugate pad), 5 ... Absorption pad (absorption member) , 6 ... Base (support member)

Claims (4)

An absorption pad used as a constituent member of an immunochromatographic test kit,
It is an integral sponge body having hydrophilicity,
The sponge body is made of a pressed polyvinyl acetal resin porous material,
The porosity of the sponge body is 40% or more and 95% or less,
The absorbent pad, wherein an average pore diameter of the sponge body is reduced to 10 μm or less by the press working. The absorbent pad according to claim 1,
An absorbent pad, wherein the sponge body has a water retention of 70% or more. The absorbent pad according to claim 1 or 2,
The absorbent pad, wherein the water absorption rate of the sponge body is 2.0 mg / min or more. The absorbent pad according to any one of claims 1 to 3 ,
The absorbent pad, wherein the sponge body is reduced in thickness by the pressing so that a volume change rate before pressing is 75% or less.

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