Detection test strip as well as preparation method and application thereof
By using covalent cross-linking to fix the antibodies on the detection line and the quality control line, the problem of easy signal loss in the prior art is solved, high sensitivity, accuracy and repeatability are achieved, and detection time is shortened.
Patent Information
- Application Number
- CN202510278595.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-10
- Publication Date
- 2025-07-18
AI Technical Summary
In the existing immunochromatography detection methods, the color-developing signals of the detection line and the quality control line are easily washed away by liquid during the chromatography process, resulting in poor sensitivity, accuracy and repeatability of the detection results, and a long detection time.
The antibodies on the detection line and the quality control line are fixed by covalent cross-linking through polymer materials (such as aminochitosan) and crosslinking agents (such as polyethylene glycol diglycidyl ether), and the antibodies are protected by binding protecting agents (such as polypeptides or polyamino acids) to avoid signal loss during chromatography.
It improves the sensitivity, accuracy and repeatability of the detection results, shortens the detection time, and ensures the stability of the detection signal.
Smart Images
Figure FT_1 
Figure FT_2 
Figure FT_3
Abstract
Description
Technical Field
[0001] The present invention relates to the field of detection technology, in particular to a detection test strip and a preparation method and application thereof. Background Art
[0002] Oxidized low-density lipoprotein is an important atherogenic lipoprotein. As an independent risk factor for atherosclerosis, it plays an important role in the occurrence and development of atherosclerosis. It can induce vascular endothelial cell damage, induce the adhesion of monocytes and endothelial cells, and play a role in the formation of foam cells and the stability of plaques. Currently, the detection methods on the market are mainly immunochromatography, enzyme-linked immunosorbent assay, immunoturbidimetry and chemiluminescence. Among them, immunochromatography detection is particularly fast, easy to operate and low in cost, and has received more attention. However, under the existing technology, the color development of the test line and the quality control line will cause signal loss due to the continuous chromatography of the liquid, thereby affecting the sensitivity, accuracy and repeatability of the test results.
[0003] Specifically, in the prior art, antibodies at the test line and the quality control line are mostly fixed by non-valent effects (hydrophobic effect, electrostatic effect, hydrogen bond, dipole effect, etc.). This fixation method will cause the fixed antibodies to be more or less washed away by the sample and diluent mixture due to the uninterrupted chromatography during the chromatography process, resulting in the loss of the detection signal, ultimately affecting the sensitivity, accuracy and repeatability of the test results, and also prolonging the detection time. Therefore, it is necessary to further study the immunochromatographic detection method. Summary of the invention
[0004] One of the purposes of the present invention is to provide a test strip with good sensitivity, accuracy and repeatability.
[0005] The present invention provides a test strip, which comprises a sample membrane, a marking membrane, a detection membrane and a driving membrane which are overlapped in sequence, wherein an antibody 1 marked with a signal material is attached to the marking membrane, the detection membrane comprises a detection line and a quality control line, the detection line is coated with an antibody 2 which can specifically bind to a substance to be tested, and the quality control line is coated with a secondary antibody which can specifically bind to the antibody 1; The coating of the antibody 2 is achieved by attaching a fixing solution containing the antibody 2 to the detection line position of the detection membrane and then drying it; The coating of the secondary antibody is achieved by attaching a fixing solution containing the secondary antibody to the quality control line position of the detection membrane and then drying it; The fixing liquid also includes a polymer material, a protective agent and a cross-linking agent; the polymer material is amino chitosan, the protective agent is one of polypeptides, polyamino acids or substances containing protein components, and the cross-linking agent is polyethylene glycol diglycidyl ether.
[0006] In the present invention, by introducing specific fixed components on the test line and the quality control line, and utilizing the specific cross-linking effect between the components, the detection antibody at the test line and the quality control antibody at the quality control line are respectively fixed on the test line and the quality control line in a covalent cross-linking manner. On the one hand, the effective fixation of the antibody is achieved, avoiding the washing away of the detection signal by the liquid during the continuous chromatography process. On the other hand, the loss of immunoreactivity during the chemical fixation of the antibody is reduced, ultimately ensuring the sensitivity, accuracy, and repeatability of the detection result, and at the same time shortening the detection time (the signal can reach the peak earlier).
[0007] Specifically, the high molecular material of the present invention provides a fixation carrier, which is fixed on the test line and the quality control line through specific chain entanglement and cross-linking with the membrane material molecules. The protective agent can protect the antibodies at the test line and the quality control line. The cross-linking agent can perform specific intermolecular and intramolecular cross-linking on these components. The antibodies include the detection antibody (antibody 1) and the quality control antibody (secondary antibody). Among them, the detection antibody is distributed on the test line, and the quality control antibody is distributed on the quality control line. Taking the double antibody sandwich method as an example, the test line is used to capture the antigen captured by the detection antibody 1 labeled with the signal substance, and the quality control line is used to capture the detection antibody 1 labeled with the signal substance that has not captured the antigen. Through the test strip of the present invention, the accurate detection of the antigen substance can be effectively achieved.
[0008] In the present invention, the molecular weight of chitosan amine is 5000 - 100000 Da, and the degree of amination is 10% - 40%. The molecular weight of polyamino acid is 2000 - 50000 Da, and the molecular weight of polyethylene glycol diglycidyl ether is 2000 - 20000 Da. If the degree of amination of chitosan amine decreases, its water solubility will be affected.
[0009] In the test strip of the present invention, the concentration of chitosan amine in the fixing solution is 0.08 - 0.12%, the concentration of the protective agent is 0.04 - 0.06%, the concentration of polyethylene glycol diglycidyl ether is 0.8 - 1.2%, and the solvent is PBS with a pH of 7.5 - 7.7 and a concentration of 9 - 11 mM.
[0010] In the test strip of the present invention, when preparing the test line, the concentration of antibody 2 in the fixing solution is 0.5 - 0.7 mg / mL, and the attachment amount of the fixing solution containing antibody 2 is 0.07 - 0.09 μL / cm 2 ; When preparing the quality control line, the concentration of the secondary antibody in the fixing solution is 0.8 - 1.2 mg / mL, and the attachment amount of the fixing solution containing the secondary antibody is 0.008 - 0.012 μL / cm 2 。
[0011] In the present invention, the concentrations of each component are appropriate, which can balance the cost and the detection effect.
[0012] In the test strip of the present invention, the overlapping width of the sample membrane and the labeled membrane is 1.8 - 2.2 mm; the overlapping width of the labeled membrane and the detection membrane is 1.8 - 2.2 mm; the overlapping width of the detection membrane and the driving membrane is 3.8 - 4.2 mm; the detection line is 8 - 12 mm away from the edge of the labeled membrane near the detection line, and the quality control line is 8 - 12 mm away from the edge of the driving membrane near the quality control line; The length of the sample membrane is 13 - 17 mm, the length of the labeled membrane is 8 - 12 mm, the length of the detection membrane is 23 - 27 mm, and the length of the driving membrane is 28 - 32 mm; the width of the test strip is 3.8 - 4.2 mm; the sample membrane, the labeled membrane, the detection membrane, and the driving membrane that are overlapped in sequence are integrally attached to the PVC substrate.
[0013] Those skilled in the art can also adjust the size of the test strip of the present invention according to the detection and product requirements.
[0014] In the test strip of the present invention, the materials of the sample membrane and the labeled membrane are independently glass fiber, filter paper, non-woven fabric, or polyester fiber; the material of the detection membrane is nitrocellulose or polyester fiber; the material of the driving membrane is cellulose; the signal material on the labeled membrane is fluorescent dye, fluorescent microsphere, colloidal gold, or colored latex microsphere; The polyamino acid is polylysine, polyserine, polyasparagine, polyglutamic acid, or polytyrosine; the substance containing protein components is bovine serum albumin, fetal bovine serum, casein, gelatin, or skim milk powder.
[0015] In the present invention, the protective agent is preferably a polypeptide rich in amino groups, polyamino acid, or a substance containing protein components, and more preferably a substance containing protein components rich in amino groups, so as to facilitate its stable protective effect on antibodies at the detection line or the quality control line.
[0016] In the test strip of the present invention, the sample membrane is obtained by dipping it in a treatment solution and then drying; The labeled membrane is obtained by first dipping it in a treatment solution and then drying, and then attaching a solution containing antibody 1 labeled with a signal material and then drying; The treatment solution includes 0.008 - 0.012% of Tween 20, and the solvent is PBS with a pH of 7.5 - 7.7 and a concentration of 9 - 11 mM; The solution containing antibody 1 labeled with a signal material also includes 9 - 11% of trehalose, 0.08 - 0.12% of BSA, and 0.08 - 0.12% of Tween 20. The concentration of antibody 1 labeled with a signal material in the solution is 0.08 - 0.12%, and the attachment amount of the solution containing antibody 1 labeled with a signal material on the labeled membrane is 0.8 - 1.2 μL / cm 2 .
[0017] The present invention also provides a method for preparing the above-mentioned test strip. First, the sample membrane, the labeled membrane, the detection membrane, and the driving membrane are prepared separately, and then they are assembled.
[0018] The present invention also provides a fixing solution for antibodies, which comprises antibodies to be fixed, a polymer material, a protective agent, and a cross-linking agent; the polymer material is amino chitosan, the protective agent is one of polypeptide, polyamino acid, or a substance containing protein components, and the cross-linking agent is polyethylene glycol diglycidyl ether; preferably, the concentration of the antibodies to be fixed in the fixing solution is 0.5 - 1.5 mg / mL, the concentration of amino chitosan is 0.08 - 0.12%, the concentration of the protective agent is 0.04 - 0.06%, the concentration of polyethylene glycol diglycidyl ether is 0.8 - 1.2%, and the solvent is PBS with a pH of 7.5 - 7.7 and a concentration of 9 - 11 mM.
[0019] The fixing solution of the present invention can be used for the preparation of test strips, thereby improving the accuracy of detection results.
[0020] The present invention also provides the application of the above-mentioned test strip or fixing solution in improving the color development stability of immunochromatographic assay.
[0021] The present invention also provides a method for detecting an antigen, which uses the above-mentioned test strip and performs detection by immunochromatography.
[0022] The beneficial effects of the present invention are at least as follows: The present invention avoids the detection signal of the analyte being washed away by the liquid during the continuous chromatography process, ultimately ensuring the sensitivity, accuracy, and repeatability of the detection results, and at the same time shortening the detection time. Description of the Drawings
[0023] Figure 1 It is a schematic structural diagram of the test strip.
[0024] Figure 2 It is a linear fitting diagram of the detection results.
[0025] Figure 3 It is the result of the change of T / C value with the detection time. Detailed Embodiments
[0026] The preferred embodiments of the present invention will be described in detail below in conjunction with the examples. It should be understood that the following examples are given only for the purpose of illustration and are not used to limit the scope of the present invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from the purpose and spirit of the present invention.
[0027] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods. The materials, reagents, etc. used in the following examples can be obtained from commercial sources or prepared by conventional methods in the art unless otherwise specified. In the specific implementation part of the present invention, the molecular weight of amino chitosan is 20,000 Da, the degree of amination is 15%, the molecular weight of polylysine is 10,000 Da, and the molecular weight of polyethylene glycol diglycidyl ether is 6,000 Da.
[0028] Example 1 This example provides a test strip of the present invention and its application, specifically as follows: The test strip includes a sample membrane, a labeled membrane, a detection membrane, and a driving membrane. The detection membrane includes a detection line and a quality control line. Among them, the materials of the sample membrane and the labeled membrane are both glass fiber, the material of the detection membrane is nitrocellulose, and the material of the driving membrane is cellulose.
[0029] The sample membrane (size 30 cm × 15 mm) is treated by dip coating with a treatment solution. The treatment solution is 10 mM PBS (pH 7.6) containing 0.01% Tween 20. Soak for 5 s, lift it up and place it on a flat plate, and air dry at room temperature for 24 h.
[0030] The labeled membrane (size 30 cm × 10 mm) is treated by dip coating with a treatment solution. The treatment solution is 10 mM PBS (pH 7.6) containing 0.01% Tween 20. Soak for 5 s, lift it up and place it on a flat plate, and air dry at room temperature for 24 h. A solution containing detection antibody 1 (Ruihan (Beijing) Biotechnology Co., Ltd., oxL-03) / fluorescent microsphere conjugate is also sprayed on the labeled membrane. The conjugation of detection antibody 1 and fluorescent microspheres adopts the conventional EDC / NHS conjugation method. The specific conjugation method is as follows: 0.2 mL of 1‰ carboxylated fluorescent microspheres (200 nm) are dispersed with pH 7.0 phosphate buffer (10 mM), 0.4 mL of 10 mg / mL EDC (dissolved in 10 mM pH 7.0 phosphate buffer) and 0.4 mL of 10 mg / mL NHS (dissolved in 10 mM pH 7.0 phosphate buffer) are added and mixed evenly. After reacting for 15 minutes, 0.2 mL of 2 mg / mL detection antibody 1 is added, and the reaction is carried out at room temperature for 3 h. Centrifuge at 10,000 rpm for 15 min, and discard the supernatant to obtain the detection antibody 1 / fluorescent microsphere conjugate. When spraying the solution containing the detection antibody 1 / fluorescent microsphere conjugate, a concentration of 0.1% is used, 10 mM PBS (pH 7.6) is used as the solvent, and it also contains trehalose with a final concentration of 10%, BSA with a concentration of 0.1%, and Tween 20 with a concentration of 0.1%. The spraying amount is 1.0 μL / cm 2 . After spraying, the labeled membrane is air dried at room temperature for 72 h.
[0031] The spraying solution at the test line on the test membrane is a fixing solution containing detection antibody 2 (Ruihan (Beijing) Biotechnology Co., Ltd., oxL-05), with the concentration of antibody 2 being 0.6 mg / mL. It also contains chitosan amine with a final concentration of 0.1%, polylysine with a final concentration of 0.05%, and polyethylene glycol diglycidyl ether with a final concentration of 1%. The solvent is 10 mM PBS (pH 7.6). The spraying volume is 0.08 μL / cm 2 . After spraying, it is dried at room temperature for 72 h. The spraying solution at the control line is a fixing solution containing goat anti-mouse IgG (sigma, M6898), with the concentration of goat anti-mouse IgG being 1.0 mg / mL. It also contains chitosan amine with a final concentration of 0.1%, polylysine with a final concentration of 0.05%, and polyethylene glycol diglycidyl ether with a final concentration of 1%. The solvent is 10 mM PBS (pH 7.6). The spraying volume is 0.01 μL / cm 2 . After spraying, it is dried at room temperature for 72 h.
[0032] Driving membrane: The driving membrane is filter paper, which is used after being dried at 100 °C for 24 h.
[0033] Grouping plates and cutting strips: The sample membrane (15 mm in length), the labeling membrane (10 mm in length), the test membrane (25 mm in length), and the driving membrane (30 mm in length) are sequentially overlapped and pasted on a PVC substrate in the following way (the overlapping widths between the sample membrane and the labeling membrane, and between the labeling membrane and the test membrane are 2 mm; the overlapping width between the test membrane and the driving membrane is 4 mm). The distance from the test line to the near-test-line side edge of the labeling membrane is about 8 mm, and the distance from the control line to the near-control-line side edge of the driving membrane is about 10 mm. The combined large plate is cut into narrow strips with a width of 4.0 mm to prepare test strips. The schematic structural diagram is as Figure 1 shown.
[0034] This example also provides a control test strip. Its specific structure and preparation method are the same as above, except that when preparing the test line and the control line on the test membrane, 5% glutaraldehyde is added to the test line antibody and the control line antibody respectively, and chemical cross-linking is carried out by pre-mixing method. Then, 5% bovine serum albumin, 5% sucrose, 5% PVP, and 5% calf serum are mixed in. The solvent is 10 mM PBS (pH 7.6). The spraying volume is 0.01 μL / cm 2 . After spraying, it is dried at room temperature for 72 h.
[0035] The oxidized low-density lipoprotein reference products with concentrations of 0.2 U / L, 0.5 U / L, 1 U / L, 3 U / L, 5 U / L, 10 U / L, 50 U / L, 100 U / L, and 200 U / L were detected using the test strip of the present invention and a control test strip respectively. Each reference product was detected twice repetitively. After 10 minutes, the fluorescence intensity results at 650 nm of the test line were read, and the concentration of the analyte was calculated according to the standard curve. The test results are shown in Table 1 below. It can be seen from the results in the table that the fluorescence intensity at the test line of the control test strip is only about 64% of that at the test line of the test strip of the present invention, indicating that the antibody immobilized on the test line of the test strip of the present invention retains more immunoreactivity, thus being able to capture more fluorescent microspheres and emit higher fluorescence intensity.
[0036] Table 1 Summary Table of Test Results Example 2 In this example, the test strips of the present invention prepared in Example 1 were used to detect the oxidized low-density lipoprotein reference products with concentrations of 0.2 U / L, 0.5 U / L, 1 U / L, 3 U / L, 5 U / L, 10 U / L, 50 U / L, 100 U / L, and 200 U / L respectively. Each reference product was detected 5 times repetitively. After 10 minutes, the fluorescence intensity results at 650 nm of the test line were read, and the concentration of the analyte was calculated according to the standard curve. The test results are shown in Table 2 below. The linear fitting graph of the test results is shown in Figure 2 . The linear determination coefficient is 0.9996, and both the CV and the deviation from the reference substance do not exceed 10%. Especially, the reference substance concentrations below 5 U / L can also be accurately detected, with high sensitivity.
[0037] Table 2 Summary Table of Test Results Comparative Example 1 This comparative example provides a control test strip, whose specific structure and preparation method are the same as those in Example 1, except that when preparing the test line and the quality control line of the control strip, polyvinyl alcohol, polylysine, and polyethylene glycol diglycidyl ether are not added to the spraying solution. The sample membrane, the labeled membrane, the test membrane, and the driving membrane were assembled and cut into test strips with a width of 4.0 mm. The control test strip was used to detect the oxidized low-density lipoprotein reference products with concentrations of 0.2 U / L, 0.5 U / L, 1 U / L, 3 U / L, 5 U / L, 10 U / L, 50 U / L, 100 U / L, and 200 U / L respectively. Each reference product was detected twice repetitively. After 10 minutes, the fluorescence intensity results at 650 nm of the test line were read, and the concentration of the analyte was calculated according to the standard curve. The test results are shown in Table 3 below.
[0038] Table 3 Summary Table of Test Results Experimental Example The test strips of the present invention prepared in Example 1 and the control test strips prepared in Comparative Example 1 in this experimental example were used to detect the oxidized low-density lipoprotein reference product at 5 U / L, and the fluorescence signals of the T line were detected at the 5th minute, 10th minute, 15th minute, 20th minute, and 25th minute respectively. The results are as Figure 3 shown. In the initial stage of Comparative Example 1, as the detection time progressed, the detection signal gradually increased and reached a peak. After that, as the chromatography proceeded, the signal was gradually washed away, resulting in a decrease in the T / C value. However, the test strips of the present invention can effectively fix the detection signal and ensure that the T / C value remains constant within a longer time range.
[0039] Comparative Example 2 This comparative example provides a test strip and its application. The specific structure and preparation method of the test strip are the same as those in Example 1, except that when preparing the detection line and the quality control line, chitosan amine in the spraying solution is replaced with polyvinyl alcohol with a molecular weight of 18,000 Da. Then, the oxidized low-density lipoprotein reference substance was detected, and the results are shown in Table 4 below.
[0040] Table 4 Summary Table of Detection Results Comparative Example 3 This comparative example provides a test strip and its application. The specific structure and preparation method of the test strip are the same as those in Example 1, except that when preparing the detection line and the quality control line, polyethylene glycol diglycidyl ether in the spraying solution is replaced with polypropylene glycol diglycidyl ether with a molecular weight of 6,000 Da. Then, the oxidized low-density lipoprotein reference substance was detected, and the results are shown in Table 5 below.
[0041] Table 5 Summary Table of Detection Results Although the present invention has been described in detail with general descriptions and specific embodiments above, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.
Claims
1. A test strip, characterized in that, The test strip includes a sample membrane, a labeled membrane, a detection membrane, and a driving membrane that are sequentially overlapped. An antibody 1 labeled with a signal material is attached to the labeled membrane. The detection membrane includes a test line and a quality control line. An antibody 2 capable of specifically binding to the substance to be detected is coated on the test line, and a secondary antibody capable of specifically binding to the antibody 1 is coated on the quality control line; The coating of the antibody 2 is achieved by attaching a fixing solution containing the antibody 2 at the test line position of the detection membrane and then drying; The coating of the secondary antibody is achieved by attaching a fixing solution containing the secondary antibody at the quality control line position of the detection membrane and then drying; The fixing solution further includes a polymer material, a protective agent, and a crosslinking agent; the polymer material is chitosan amino, the protective agent is one of polypeptide, polyamino acid, or a substance containing a protein component, and the crosslinking agent is polyethylene glycol diglycidyl ether.
2. The test strip according to claim 1, characterized in that, In the fixing solution, the concentration of chitosan amino is 0.08 - 0.12%, the concentration of the protective agent is 0.04 - 0.06%, the concentration of polyethylene glycol diglycidyl ether is 0.8 - 1.2%, and the solvent is PBS with a pH of 7.5 - 7.7 and a concentration of 9 - 11 mM.
3. The test strip according to claim 1 or 2, characterized in that, When preparing the detection line, the concentration of antibody 2 in the fixing solution is 0.5 - 0.7 mg / mL, and the attachment amount of the fixing solution containing antibody 2 is 0.07 - 0.09 μL / cm 2 ; When preparing the quality control line, the concentration of the secondary antibody in the fixing solution is 0.8 - 1.2 mg / mL, and the attachment amount of the fixing solution containing the secondary antibody is 0.008 - 0.012 μL / cm 2 .
4. The test strip according to any one of claims 1 - 3, wherein The overlapping width of the sample membrane and the labeled membrane is 1.8 - 2.2 mm; The overlapping width of the labeled membrane and the detection membrane is 1.8 - 2.2 mm; The overlapping width of the detection membrane and the driving membrane is 3.8 - 4.2 mm; The test line is 8 - 12 mm away from the edge of the labeled membrane near the test line, and the quality control line is 8 - 12 mm away from the edge of the driving membrane near the quality control line; The length of the sample membrane is 13 - 17 mm, the length of the labeled membrane is 8 - 12 mm, the length of the detection membrane is 23 - 27 mm, and the length of the driving membrane is 28 - 32 mm; the width of the test strip is 3.8 - 4.2 mm; The sequentially overlapped sample membrane, labeled membrane, detection membrane, and driving membrane are integrally attached to a PVC substrate.
5. The test strip according to any one of claims 1 - 4, wherein The materials of the sample membrane and the labeled membrane are independently glass fiber, filter paper, non - woven fabric, or polyester fiber; the material of the detection membrane is nitrocellulose or polyester fiber; the material of the driving membrane is cellulose; The signal material on the labeled membrane is a fluorescent dye, fluorescent microsphere, colloidal gold, or colored latex microsphere; The polyamino acid is polylysine, polyserine, polyasparagine, polyglutamic acid, or polytyrosine; The substance containing a protein component is bovine serum albumin, fetal bovine serum, casein, gelatin, or skim milk powder.
6. The test strip according to any one of claims 1 - 5, wherein The sample membrane is obtained by dip - coating a treatment solution and then drying; The labeled membrane is obtained by first dip - coating a treatment solution and drying, and then attaching a solution containing the antibody 1 labeled with a signal material and drying; The treatment solution includes 0.008 - 0.012% of Tween 20, and the solvent is PBS with a pH of 7.5 - 7.7 and a concentration of 9 - 11 mM. The solution containing antibody 1 labeled with a signal material further includes 9-11% trehalose, 0.08-0.12% BSA, and 0.08-0.12% Tween 20. The concentration of antibody 1 labeled with a signal material in the solution is 0.08-0.12%, and the attachment amount of the solution containing antibody 1 labeled with a signal material to the labeled membrane is 0.8-1.2 μL / cm 2 .
7. A method for preparing the test strip according to any one of claims 1-6, characterized in that, Prepare the sample membrane, labeling membrane, detection membrane and driving membrane separately first, and then assemble them.
8. A fixing solution for an antibody, characterized in that, It includes the antibody to be immobilized, polymer material, protective agent and cross-linking agent; the polymer material is amino chitosan, the protective agent is one of polypeptide, polyamino acid or substance containing protein component, and the cross-linking agent is polyethylene glycol diglycidyl ether; Preferably, the concentration of the antibody to be immobilized in the fixing solution is 0.5 - 1.5 mg / mL, the concentration of amino chitosan is 0.08 - 0.12%, the concentration of the protective agent is 0.04 - 0.06%, the concentration of polyethylene glycol diglycidyl ether is 0.8 - 1.2%, and the solvent is PBS with pH 7.5 - 7.7 and concentration of 9 - 11 mM.
9. Application of the test strip according to any one of claims 1 - 6 or the fixing solution according to claim 8 in improving the color development stability of immunochromatographic assay.
10. A method for detecting an antigen, characterized in that, Use the test strip according to any one of claims 1 - 6 for detection by immunochromatography.