JP7272583B2 - Method for surface treatment of membrane for immunochromatographic assay - Google Patents

Description

The present invention relates to a surface treatment method for immunochromatographic assay membranes.

Immunochromatographic assays are widely used as simple immunoassays using antigen-antibody reactions. Immunochromatographic assays are easy to operate and can be measured in a short period of time, so they are widely used for clinical examinations and diagnoses that require prompt reporting, such as pregnancy diagnosis and confirmation of influenza infection. Patent document 1).

Porous membranes made of cellulose esters such as cellulose nitrate and cellulose acetate are generally used for immunochromatographic assays. However, it is known that dust composed of cellulose ester is simultaneously formed as particulate impurities in the membrane formation process when manufacturing such a membrane, and that these dusts are present on the upper surface side of the membrane. In immunochromatographic assays, specimens move through the membrane due to capillary action, so the presence of dust in the membrane may affect test performance. Furthermore, there is a possibility of causing contamination of the manufacturing process in the manufacture of the test kit, and removing such dust from the membrane is a problem.

In order to solve this problem, it has been proposed to cast a cellulose ester polymer solution on a support and then mechanically brush the surface of the membrane while rinsing it with a cleaning solution to remove dust from the membrane (see, for example, Patent Document 1).

U.S. Pat. No. 7,807,475

Yuriko Koyama, Kei Sugita, "Protein detection method using immunochromatography", Bunseki, 170 (2018)

By brushing the surface of the cast film before drying as described in Patent Document 1, impurities can be removed from the membrane together with the cellulose ester particles. However, it was pointed out that the amount of surfactant in the membrane was reduced, adversely affecting the hydrophilic properties. Attempting to compensate for the loss of surfactant by an additional step increases manufacturing costs and can affect the variability of the final membrane quality.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for removing dust from an immunochromatographic assay membrane without causing any inconvenience.

In order to achieve the above objects, the present inventors have made intensive studies and found that the amount of dust on the surface is reduced by treating the surface of an immunochromatographic assay membrane using a flexible sheet having a specific surface. can be reduced to further improve the uniformity of the membrane surface. That is, the present invention is a method for surface treatment of an immunochromatographic assay membrane, wherein a flexible sheet having one surface coated with a pressure-sensitive adhesive or adhesive is brought into close contact with the surface of the immunochromatographic assay membrane, In the surface treatment method, the flexible sheet is peeled off from the surface of the immunochromatographic assay membrane.

INDUSTRIAL APPLICABILITY According to the present invention, dust can be removed from an immunochromatographic assay membrane without any inconvenience, and the surface uniformity of the membrane can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is photographs showing immunochromatographic measurement results of membranes before and after surface treatment using a flexible sheet having a pressure-sensitive adhesive or adhesive applied to one side, and Fig. 1(a) shows Examples 1 to 9 and Comparative Fig. 1(b) is a photograph of the negative specimens of Examples 1 to 9 and Comparative Example 1 after the total amount of the test liquid was sucked up and dried. Fig. 2 shows the results of immunochromatographic measurement of a membrane before and after surface treatment using a flexible sheet having a pressure-sensitive adhesive or an adhesive applied to one surface, showing the results of sucking up the entire amount of a positive sample test solution and drying. (a) are photographs of Examples 12 to 14 and Comparative Example 1, FIG. 2(b) are photographs of Examples 10, 15 to 18 and Comparative Example 2, and FIG. 2(c) are photographs of Examples 11 and 19 22, which is a photograph of Comparative Example 3. Fig. 3 shows the results of immunochromatographic measurement of a membrane before and after surface treatment using a flexible sheet having one surface coated with a pressure-sensitive adhesive or adhesive, and is a photograph after sucking up the entire amount of the test solution of a negative specimen and drying. (a) are photographs of Examples 12 to 14 and Comparative Example 1; FIG. 3(b) are photographs of Examples 10, 15 to 18 and Comparative Example 2; FIG. 3(c) are photographs of Examples 11 and 19 22, which is a photograph of Comparative Example 3. SEM photographs of Sample 1 before and after surface treatment using a flexible sheet having one surface coated with a pressure-sensitive adhesive or adhesive, FIG. FIG. 4(b) is a photograph of Example 9 after surface treatment, and FIG. 4(c) is a photograph of Comparative Example 1 (untreated). SEM photographs of Sample 2 before and after surface treatment using a flexible sheet having one surface coated with a pressure-sensitive adhesive or adhesive, FIG. FIG. 5(b) is a photograph of Example 17 after surface treatment, and FIG. 5(c) is a photograph of Comparative Example 2 (untreated). Fig. 6(a) shows SEM photographs of Sample 3 before and after surface treatment using a flexible sheet having one surface coated with a pressure-sensitive adhesive or adhesive; FIG. 6(b) is a photograph of Example 21 after surface treatment, and FIG. 6(c) is a photograph of Comparative Example 3 (untreated).

The immunochromatographic assay membrane (hereinafter also simply referred to as membrane) surface-treated by the method according to the present invention is made of cellulose ester that adsorbs proteins. Specific examples of such membranes include membranes for immunochromatography manufactured by Toyo Roshi Kaisha, Ltd.

The membrane is porous and often has nitrocellulose dust attached to its surface. Nitrocellulose dust may be present in the pores of the membrane. In the present invention, it was possible to reduce the nitrocellulose powder by treating the surface of the membrane with a given flexible sheet. Furthermore, it has become possible to improve the uniformity of the surface of the membrane.

The membrane is preferably backside fixed to a plastic support prior to surface treatment. Plastic supports include those that are large enough to allow the membrane to be placed thereon and that are self-fixating. The material of the plastic support is not particularly limited, and for example, a support made of polyethylene terephthalate (PET) can be used.

The membrane may be secured on the back to the plastic support by double-sided tape. Alternatively, a solution (dope) in which cellulose ester is dissolved in an organic solvent can be used to immobilize the membrane on the plastic support. In this case, the membrane is immobilized on the plastic support by coating the surface of the plastic support with the solution and evaporating the solvent.

A flexible sheet having one surface coated with a pressure-sensitive adhesive or adhesive is brought into close contact with the surface of the membrane fixed to the plastic support. Specifically, flexible sheets include adhesive tapes and laminated films. The flexible sheet is preferably sized to completely cover the surface of the membrane.

The adhesive tape has an adhesive surface in which an adhesive is applied to a base material. The material of the plastic sheet or nonwoven fabric used for the adhesive tape can be selected from, for example, polystyrene, polyethylene, polypropylene, polyester, regenerated cellulose, and the like. Suitable adhesives for adhesive tapes include, for example, rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, and the like.

A laminate film has an adhesive surface in which a heat-adhesive adhesive is applied to a base material. The material of the plastic sheet used for the laminate film can be selected from, for example, polystyrene, polyethylene, polypropylene, polyester, and the like. Suitable adhesives for laminate films include, for example, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid Copolymer (EMAA), polyethylene (PE), ionomer polyethylene, etc. or combinations thereof.

(Surface treatment using adhesive tape)
The adhesive surface of the adhesive tape coated with the adhesive is placed on the surface of the membrane, and the membrane and the adhesive tape are pressure-bonded using nip rolls. After that, the adhesive tape is peeled off from the surface of the membrane. It is preferable that the adhesive tape be peeled off at a uniform speed.

The adhesive strength of the adhesive tape is generally about 1 to 20 N/24 mm. By peeling the adhesive tape adhered by the adhesive force from the surface of the membrane, the nitrocellulose dust moves from the surface of the membrane to the adhesive surface of the adhesive tape. Furthermore, nitrocellulose dust present inside the pores of the membrane can also migrate to the adhesive tape. The amount of nitrocellulose dust on the membrane is reduced and the surface uniformity of the membrane is enhanced.

(Surface treatment using laminate film)
When a laminate film is used, the adhesive surface of the laminate film coated with the adhesive is placed on the surface of the membrane, and the membrane and laminate film are heated using a heating nip roll at 70 to 120°C, preferably 80 to 110°C. crimp. After that, the laminate film is peeled off from the surface of the membrane. It is preferable that the laminate film be peeled at a uniform speed.

As with the adhesive tape, when a laminate film is used, the nitrocellulose dust moves from the surface of the membrane to the adhesive surface of the laminate film by peeling off from the surface of the membrane. Nitrocellulose dust present inside the pores of the membrane can also migrate to the laminate film. The amount of nitrocellulose dust on the membrane is reduced and the surface uniformity of the membrane is enhanced.

In the method of the present invention, the surface of the membrane is treated by a simple operation of peeling off the flexible sheet after closely contacting the membrane with a flexible sheet coated with a pressure-sensitive adhesive or adhesive. The method of the present invention makes it possible to remove the dust in the membrane without any inconvenience, and also to improve the uniformity of the surface of the membrane.

Since the treated membrane is made of nitrocellulose and is porous, it may be affected by environmental factors such as temperature and humidity. Temperature and humidity also affect the performance of flexible sheets. In order not to hinder the movement of the nitrocellulose powder from the surface of the membrane to the flexible sheet, the surface treatment of the present invention is desirably performed in an environment with a temperature of about 5 to 35° C. and a relative humidity of about 45 to 85%. be

The present invention will be specifically described below based on examples, but these do not limit the object of the present invention, and the present invention is not limited to these examples. The manufacturing method and testing method of the membranes shown in the examples are as follows.

1. Production of Membrane First, an immunochromatographic assay membrane to be subjected to surface treatment was produced by the following method.
Specifically, 4.6% by mass of nitrocellulose resin, 0.2% by mass of cellulose acetate resin, 43.7% by mass of acetone, 46.2% by mass of propanol, 2.0% by mass of isopropyl alcohol, and 3.4% by mass of water. % by mass was placed in a tank and stirred to obtain a uniform membrane-forming solution. Thereafter, the membrane-forming solution was cast on a support (polyester film) heated to 33° C. in an atmosphere adjusted to a humidity of 55%, and the solvent was evaporated to solidify the membrane-forming solution. Then, it was dried to obtain a membrane.
Sodium dodecylbenzenesulfonate was added to the resulting membrane to obtain sample 1. A test piece having a width of 10 mm and a length of 50 mm was cut out from sample 1, and water was sucked up from one end of the test piece in the length direction. As a result, it took 109 seconds for water to be sucked up to a height of 40 mm.

Furthermore, 4.2% by mass of nitrocellulose resin, 0.1% by mass of cellulose acetate resin, 42.7% by mass of acetone, 45.2% by mass of propanol, 7.3% by mass of isopropyl alcohol, and 6.1% by mass of water It was placed in a tank and stirred to obtain a uniform membrane-forming solution. After that, a sample 2 was obtained in the same manner as the sample 1. A test piece having a width of 10 mm and a length of 50 mm was cut from sample 2, and water was sucked up from one end of the test piece in the length direction. As a result, it took 72 seconds for water to be sucked up to a height of 40 mm.

Furthermore, 4.7% by weight of nitrocellulose resin, 0.2% by weight of cellulose acetate resin, 44.3% by weight of acetone, 46.8% by weight of propanol, 7.3% by weight of isopropyl alcohol, and 2.0% by weight of water was placed in a tank and stirred to form a uniform membrane-forming solution. Thereafter, in an atmosphere adjusted to a humidity of 55%, the film-forming solution was cast onto a polyester film as a support heated to 35°C. Except for this, Sample 3 was obtained in the same manner as described above. A test piece having a width of 10 mm and a length of 50 mm was cut from sample 2, and water was sucked up from one end of the test piece in the length direction. As a result, it took 180 seconds for water to be sucked up to a height of 40 mm.

2. Change in amount of dust By treating the surface of the membrane with the method of the present invention, the amount of cellulose ester dust in the membrane is reduced. A reduction in the amount of dust can be confirmed indirectly by the following method. Specifically, the absorbance of the extract obtained from the membrane before and after the surface treatment is measured, and the change in the amount of nitrocellulose dust on the membrane can be determined from the change in absorbance.

First, six membrane test pieces (5 mm×40 mm) are prepared. A test piece before surface treatment is placed in a test tube, and 5 mL of 0.05% sodium dodecylbenzenesulfonate (SDBS) is added. The mixture is stirred for 20 seconds with a vortex mixer to obtain an extract, and its absorbance (560 nm) is measured with a spectrophotometer.
For the surface-treated membrane, an extract is obtained as a test piece in the same manner, the absorbance is measured in the same manner, and the dust change rate is calculated by the following formula.

ダスト変化率の値が１より小さい場合、表面処理によってメンブレンにおける粉が減少したものと判断できる。

If the value of the dust change rate is less than 1, it can be determined that the dust on the membrane has been reduced by the surface treatment.

3. Measurement of Adhesive Strength of Adhesive Tape The adhesive strength of the adhesive tape was measured as 180° peeling adhesive strength against a test plate according to JIS Z0237 "Adhesive tape/adhesive sheet test method". Specifically, a 24 mm wide adhesive tape is attached to a SUS304 test plate using a pressure roller with a mass of 2 kg, and one end of the adhesive tape is fixed to a chuck of a universal testing machine (AGS-H manufactured by Shimadzu Corporation). bottom. By operating the tester at a speed of 300 mm / min, the adhesive tape is peeled off from the test plate, and the average of the test force in the range peeled off by 50 mm from the point displaced by 25 mm from the start of operation Adhesion strength (N / 24 mm) and

4. Immunochromatographic measurement Immunochromatographic measurement is a system in which human chorionic gonadotropin (hCG) is measured as a substance to be detected, and is performed by a half-strip method in which an absorption pad is attached to the membrane and a mixed solution of labeled antibody and hCG is developed.

(1) Preparation of Detection Line and Control Line on Chromatography Medium As a medium for immunochromatography, a cellulose ester membrane lined with a polyester sheet having a thickness of 100 μm and prepared by the method described above was used. A detection line in which an hCG-recognizing antibody was immobilized as a capture antibody and a control line in which a mouse IgG-recognizing antibody as a labeling antibody was immobilized were set on this membrane.
ah. Test Line Antibody Solution The anti-hCG antibody was diluted with 50 mM phosphate buffer (pH 7.0) to give a test line antibody solution with a concentration of 0.5 mg/mL.
stomach. Antibody solution for control line A goat anti-mouse IgG antibody was diluted with phosphate-buffered saline (PBS) (pH 7.0) to a concentration of 0.5 mg/mL as an antibody solution for the control line. .
hare. Spotting on a chromatographic medium Above a. stomach. was applied to a cellulose ester membrane as a chromatography medium using an immunochromatographic dispensing system XYZ3060 manufactured by BioDot, and dried at 50° C. for 30 minutes.
workman. Blocking treatment The membrane of c above is impregnated with a 0.5% by mass casein solution (pH 8.5) containing 0.3% by mass of boric acid and 0.095% by mass of sodium azide, and is heated at 50°C for 30 minutes. dried.
E. Washing Treatment The membrane in D above was immersed in 50 mM Tris-HCl (pH 7.5) containing 0.5% by mass of sucrose and 0.01% sodium dodecylbenzenesulfonate at room temperature for 30 minutes, removed and washed at 50°C. and dried for 30 minutes.

(2) Preparation of Labeled Antibody Solution 1 mL of 50 mM phosphate buffer (pH 7.5) was added to 9 mL of colloidal gold solution (manufactured by BBI Solutions: EMGC40) and stirred, and 1.1 mL of 50 μg/mL solution of hCG recognition antibody was added. The mixture was added and stirred and allowed to stand at room temperature for 10 minutes. Furthermore, 0.5 mL of 1% by mass polyethylene glycol (average molecular weight 20000) and 10% by mass bovine serum albumin (BSA) were added and stirred.

After that, centrifugation is performed at 7500×g for 15 minutes, the supernatant is removed to leave 1 mL, and 1% by weight BSA, 0.05% by weight polyethylene glycol (average molecular weight 20,000), 150 mM sodium chloride, 0.05% by weight. 20 mL of 20 mM Tris-HCl (pH 8.2) containing 0.95% by mass of sodium azide was added and stirred.
Centrifugation was then performed at 7500×g for 15 minutes. Remove the supernatant to leave 1 mL, 1 wt% BSA, 0.05 wt% polyethylene glycol (average molecular weight 20000), 150 mM sodium chloride, 0.095 wt to an absorbance of 6.0 at 520 nm. 20 mM Tris-HCl (pH 8.2) containing 10% sodium azide was added and stirred to prepare a labeled antibody solution.

(3) Preparation of substance to be detected The hCG reagent (standard substance) was dissolved in PBS containing 1 mass% BSA, diluted to 50 mIU/mL, and used as a positive sample. PBS containing 1 mass % BSA without hCG reagent was used as a negative sample.

(4) Immunochromatographic measurement conditions The medium for immunochromatographic measurement prepared in (1) above and an absorbent pad (filter paper No. 590 manufactured by Toyo Roshi Kaisha, Ltd.) were attached to the backing sheet, and a test strip cut to a width of 5 mm with a cutter was cut. was used to perform immunochromatographic measurements by the half-strip method.
5 μL of the labeled antibody solution in (2) above and 100 μL of the test substance solution in (3) above were mixed, and the mixed solution was sucked up from the lower end of the membrane of the test strip. After 10 minutes and 20 minutes from the start of sucking up, the red coloration of the colloidal gold in the detection line and control line on the test strip was measured using an immunochromatographic reader to measure the intensity of the coloration.

5. Surface Treatment The surface treatment of the membrane of Sample 1 was performed using a flexible sheet having one surface coated with a pressure-sensitive adhesive or adhesive. The results are shown below.

(Example 1)
Using an adhesive tape (Scotch (registered trademark) peelable tape 811 manufactured by 3M) as a flexible sheet having one surface coated with an adhesive, Sample 1 was surface-treated by the method described above. The linear pressure of the nip rolls was 0.5 kgf/cm. The adhesive of this adhesive tape was an acrylic adhesive and had an adhesive strength of 0.6 N/24 mm.

(Example 2)
Sample 1 was surface-treated in the same manner as in Example 1 using an adhesive tape (surface protection tape TSP-5B manufactured by Trusco Nakayama Co., Ltd.) as a flexible sheet having one surface coated with an adhesive. The adhesive of this adhesive tape was an acrylic adhesive and had an adhesive strength of 1.3 N/24 mm.

(Example 3)
Adhesive tape (surface protective film SPV-M-6030 for metal plates manufactured by Nitto Denko Co., Ltd.) was used as a flexible sheet with an adhesive applied to one side, and sample 1 was subjected to the same surface treatment as in Example 1. did The adhesive of this adhesive tape was an acrylic adhesive and had an adhesive strength of 2.0 N/24 mm.

(Example 4)
Sample 1 was surface-treated in the same manner as in Example 1 using an adhesive tape (Scotch (registered trademark) PTFE tape 5490 manufactured by 3M) as a flexible sheet having one surface coated with an adhesive. The adhesive of this adhesive tape was a silicone-based adhesive and had an adhesive strength of 5.4 N/24 mm.

(Example 5)
Sample 1 was surface-treated in the same manner as in Example 1 using an adhesive tape (Cellotape (registered trademark) No. 405, manufactured by Nichiban Co., Ltd.) as a flexible sheet having one surface coated with an adhesive. The adhesive of this adhesive tape was a rubber-based adhesive and had an adhesive strength of 10.5 N/24 mm.

(Example 6)
Sample 1 was surface-treated in the same manner as in Example 1 using an adhesive tape (a transparent protective tape that protects against scratches manufactured by 3M) as a flexible sheet having one surface coated with an adhesive. The adhesive of this adhesive tape was an acrylic adhesive and had an adhesive strength of 15.4 N/24 mm.

(Example 7)
Sample 1 was subjected to the same surface treatment as in Example 1 using an adhesive tape (line tape E-SD for indoor smooth floors manufactured by Nitto Denko Corporation) as a flexible sheet with an adhesive applied to one side. gone. The adhesive of this adhesive tape was a rubber-based adhesive and had an adhesive strength of 19.7 N/24 mm.

(Example 8)
Using a PET-based laminate film as a flexible sheet having an adhesive applied to one surface, Sample 1 was surface-treated by the method described above. The linear pressure of the nip roll was set to 0.5 kgf/cm, and the nip roll on the laminate film side was heated to 91°C. The adhesive for this laminate film was PE+EVA.

(Example 9)
A laminate film of a PET substrate was used as a flexible sheet having one surface coated with an adhesive, and sample 1 was subjected to the same surface treatment as in Example 8. The adhesive for this laminate film was PE+EEA.

(Comparative example 1)
1 is the membrane of Sample 1 without surface treatment using a flexible sheet with a pressure sensitive adhesive or adhesive applied to one side.

Tables 1 and 2 summarize the dust change rate and immunochromatographic measurement results of Examples 1 to 9 and Comparative Example 1. Furthermore, for Examples 1 to 9 and Comparative Example 1, the photograph after sucking up the whole amount of the test solution of the positive sample and drying is shown in FIG. b).
The amount of dust was reduced compared to Comparative Example 1 in all Examples. As a result of immunochromatographic measurement, none of the examples showed a large decrease in color development intensity as compared with Comparative Example 1, and the surface treatment did not give any problem to the immunochromatographic measurement.

Samples 1 to 3 manufactured under different manufacturing conditions were subjected to surface treatment using a flexible sheet having one surface coated with an adhesive. The results are shown below.

(Example 10)
Sample 2 was subjected to the same surface treatment as in Example 3.

(Example 11)
Sample 3 was subjected to the same surface treatment as in Example 3.

(Example 12)
Sample 1 was subjected to the same surface treatment as in Example 9, except that the temperature of the nip roll was changed to 71°C.

(Example 13)
Sample 1 was subjected to the same surface treatment as in Example 9, except that the temperature of the nip roll was changed to 82°C.

(Example 14)
Sample 1 was subjected to the same surface treatment as in Example 9, except that the temperature of the nip roll was changed to 103°C.

(Example 15)
Sample 2 was surface-treated in the same manner as in Example 12.

(Example 16)
Sample 2 was surface-treated in the same manner as in Example 13.

(Example 17)
Sample 2 was surface-treated in the same manner as in Example 9.

(Example 18)
Sample 2 was surface-treated in the same manner as in Example 14.

(Example 19)
Sample 3 was surface-treated in the same manner as in Example 12.

(Example 20)
Sample 3 was surface-treated in the same manner as in Example 13.

(Example 21)
Sample 3 was surface-treated in the same manner as in Example 9.

(Example 22)
Sample 3 was surface-treated in the same manner as in Example 14.

(Comparative example 2)
The membrane of Sample 2 without surface treatment using a flexible sheet with an adhesive or adhesive applied to one side.

(Comparative Example 3)
3 is the membrane of Sample 3 without surface treatment using a flexible sheet with an adhesive or adhesive applied to one side.

Tables 3-5 summarize the results of dust change rates and immunochromatographic measurements of Examples 10-22 and Comparative Examples 2-3. Furthermore, for Examples 10 to 22 and Comparative Examples 2 to 3, the photographs after sucking up the whole amount of the test solution of the positive sample and drying are shown in FIGS. Later photographs are shown in FIGS. 3(a)-3(c).
In all examples, the amount of dust decreased compared to the comparative example. As a result of immunochromatographic measurement, in the example using the sample 2, compared with the comparative example 2, no significant decrease in color development intensity was observed. In addition, in the example using sample 3, a large decrease in color development intensity was not observed as compared with comparative example 3. Even for cellulose ester membrane samples manufactured under different manufacturing conditions, the surface treatment using a flexible sheet coated with an adhesive on one side does not cause any problems in immunochromatographic measurement.

FIG. 4 shows surface SEM photographs of Sample 1 surface-treated with an adhesive tape or laminate film and Sample 1 not treated. FIGS. 4(a) and 4(b) are photographs of the surface of Sample 1 subjected to surface treatment in Examples 3 and 9, respectively, and FIG. 4(c) is a sample of Comparative Example 1 (untreated). 1 is a surface photograph.

FIG. 5 shows surface SEM photographs of Sample 2 surface-treated with an adhesive tape or laminate film and Sample 2 not treated. 5(a) and 5(b) are photographs of the surface of Sample 2 subjected to surface treatment in Examples 10 and 17, respectively, and FIG. 5(c) is a sample of Comparative Example 2 (untreated). 2 is a surface photograph.

FIG. 6 shows surface SEM photographs of Sample 3 surface-treated with an adhesive tape or laminate film and Sample 3 not treated. 6(a) and 6(b) are photographs of the surface of Sample 3 subjected to surface treatment in Examples 11 and 21, respectively, and FIG. 6(c) is a photograph of Comparative Example 3 (untreated product). 4 is a photograph of the surface of sample 3. FIG.

All membrane samples were shown to improve surface uniformity by treatment with adhesive tapes and laminate films.

Claims (5)

A method for surface treatment of a membrane for immunochromatographic assay, comprising:
preparing an immunochromatographic assay membrane having dust on its surface,
After adhering a flexible sheet having one side coated with an adhesive or adhesive to the surface of the immunochromatographic assay membrane,
By peeling the flexible sheet from the surface of the immunochromatographic assay membrane, the dust is moved to the surface of the flexible sheet to increase the uniformity of the surface of the immunochromatographic assay membrane. A method for surface treatment of a membrane for immunochromatographic assay. 2. The surface treatment method according to claim 1, wherein the immunochromatographic assay membrane is made of cellulose ester. 3. The surface treatment method according to claim 1, wherein the flexible sheet is adhered to the surface of the immunochromatographic assay membrane by pressure bonding or thermocompression bonding. 4. The surface treatment method according to any one of claims 1 to 3, wherein the flexible sheet is an adhesive tape having an adhesive strength of 1.0 N/24 mm or more. 4. The surface treatment method according to claim 3, wherein the flexible sheet is a laminate film, and the heating temperature of the thermocompression bonding is 70 to 120.degree.

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