An immunochromatographic test kit for detecting a viscous sample

Abstract

The present application relates to the field of immunochromatography, and particularly relates to an immunochromatographic detection kit for detecting viscous samples. The present application provides a sample pad treatment liquid, characterized in that the sample pad treatment liquid comprises at least the following components: S-carboxymethyl-L-cysteine, a buffer, a surfactant, and a blocking agent. The sample pad treatment liquid of the present application can enhance the anti-interference ability of the immunochromatographic detection kit for different viscous samples and prolong the actual effective period thereof with relatively simple components, and long-term guarantee that the detection performance and color development quality of the immunochromatographic detection kit prepared based thereon remain at a very high level.

Description

Technical Field

[0001] This invention relates to the field of immunochromatography, and more specifically to an immunochromatographic assay kit for detecting viscous samples. Background Technology

[0002] Due to its simplicity, speed, and low cost, immunochromatography has wide applications in many fields, such as disease diagnosis, pesticide residues, pregnancy control, pet disease control, and disease prevention and control. However, because immunochromatographic testing generally does not involve special sample processing, traditional immunochromatographic test kits can be affected by certain types of samples (such as viscous samples), leading to abnormal results. For example, highly viscous oropharyngeal swab samples for respiratory tract testing have complex compositions and are rich in mucins, which can cause tracer particle aggregation during testing, resulting in problems such as NC membrane blockage, unclean background, or false positives; the same applies to vaginal / cervical swab samples.

[0003] While traditional immunochromatographic assay kits can adjust sample pH and filter large particles to some extent, the sample pads still present challenges with viscous samples such as oropharyngeal swabs. Chinese patent application CN117129691A discloses a test strip for detecting human chorionic gonadotropin (hCG) in saliva, wherein the sample pad is treated with a sample pad treatment solution (containing Tris, casein, Tween-20, NaCl, dodecyltrimethylammonium bromide, 4-nonylphenyl-polyethylene glycol, borax, polyvinylpyrrolidone, dithiothreitol, and L-cysteine). Although the disclosed sample pad treatment solution can eliminate false positives in saliva sample testing to some extent, it still suffers from problems such as complex composition and short shelf life. Summary of the Invention

[0004] In a first aspect, the present invention provides a sample pad treatment solution, characterized in that the sample pad treatment solution comprises at least the following components: S-carboxymethyl-L-cysteine, buffer solution, surfactant, and blocking agent.

[0005] In some embodiments, the mass fraction of the S-carboxymethyl-L-cysteine ​​includes 0.1%-5%.

[0006] As used herein, a buffer solution refers to a solution prepared from a buffer reagent and a solvent, generally a combination of a strong acid and a weak organic acid, a weak acid and its salt, a weak acid and a basic salt, a strong base and a weak organic acid, a strong acid and a weak base, or a strong base and a weak acid. The solvent is typically water.

[0007] In some embodiments, the buffer solution may be one or more of phosphate buffer, borate buffer, and tris(hydroxymethyl)glycine buffer.

[0008] In some embodiments, the concentration of the buffer solution includes 25 mM to 200 mM.

[0009] In some embodiments, the buffer solution is a tris(hydroxymethyl)methylglycine (Tricine) buffer solution.

[0010] In some embodiments, the pH of the sample pad treatment solution includes 7.6-8.4.

[0011] In some embodiments, the surfactant includes one or more of Triton X-100, Tween20, Tween80, S9, NP-40, and CHAPS.

[0012] In some embodiments, the mass fraction of the surfactant includes 0.1-5.0%.

[0013] In some embodiments, the sealing agent includes one or more of BSA, CASEIN, CASEIN-Na, gelatin, and skim milk powder.

[0014] In some embodiments, the mass fraction of the sealant includes 0.1-5.0%.

[0015] In some embodiments, the sample pad treatment solution further includes a preservative.

[0016] In some embodiments, the preservative includes one or more of ProClin 150, ProClin 200, ProClin 300, and ProClin 950.

[0017] In some embodiments, the preservative has a mass fraction of 0.02-0.2%.

[0018] In some embodiments, the sample pad treatment solution further includes neutral inorganic salts.

[0019] In some embodiments, the neutral inorganic salt includes sodium chloride and / or potassium chloride.

[0020] In some embodiments, the concentration of the neutral inorganic salt includes 25-200 mM.

[0021] In some embodiments, the sample pad treatment solution comprises the following components: S-carboxymethyl-L-cysteine, buffer solution, surfactant, blocking agent, preservative, and neutral inorganic salt.

[0022] In some embodiments, the sample pad treatment solution comprises the following components: 25mM-200mM buffer, 0.1%-5% (mass fraction) S-carboxymethyl-L-cysteine, 25-200 mM neutral inorganic salt, 0.1-5.0% (mass fraction) surfactant, 0.1-5% (mass fraction) blocking agent, and 0.02-0.2% (mass fraction) preservative.

[0023] In some embodiments, the sample pad treatment solution comprises the following components: 25 mM-200 mM tris(hydroxymethyl)methylglycine buffer, 0.1%-5% (mass fraction) S-carboxymethyl-L-cysteine, 25-200 mM NaCl, 0.1-5.0% (mass fraction) BSA, 0.1-5% (mass fraction) Triton X-100 and 0.02-0.2% (mass fraction) ProClin300.

[0024] In some embodiments, the concentration of the tris(hydroxymethyl)methylglycine buffer is 50 mM.

[0025] In some embodiments, the mass fraction of the S-carboxymethyl-L-cysteine ​​is 2%.

[0026] In some embodiments, the sealant has a mass fraction of 0.5%.

[0027] In some embodiments, the concentration of the neutral inorganic salt is 150 mM.

[0028] In some embodiments, the preservative has a mass fraction of 0.05%.

[0029] Secondly, the present invention provides a sample pad, characterized in that the sample pad is obtained by treating it with the above-mentioned sample pad treatment solution.

[0030] In some embodiments, the processing method specifically includes: wetting and / or coating the glass fiber membrane with the sample pad treatment solution, and then drying the glass fiber membrane to obtain the sample pad.

[0031] In some embodiments, the drying method includes drying at 37°C ± 1°C for 8-24 hours.

[0032] Thirdly, the present invention provides a test strip for detecting viscous samples, the test strip comprising the sample pad described above.

[0033] Fourthly, the present invention provides an immunochromatographic assay kit for detecting viscous samples, characterized in that the immunochromatographic assay kit includes a test strip, the test strip including a base plate, a sample pad, a conjugate pad, a nitrocellulose membrane and an absorbent pad disposed on the base plate in sequence.

[0034] As used herein, a viscous sample refers to a biological sample containing a certain amount of mucin. In some embodiments, the viscous sample may also contain pathogenic microorganisms, such as one or more of bacteria, viruses, fungi, and parasites. In some embodiments, the viscous sample is secreted from sites such as the mouth, nasal cavity, eyes, gastrointestinal tract, vagina, and respiratory tract. In some embodiments, the viscous sample includes oropharyngeal swab samples, nasopharyngeal swab samples, vaginal secretion samples, sputum samples, or saliva samples.

[0035] In some embodiments, the immunochromatographic assay kit is used to detect pathogenic microorganisms that cause respiratory and / or reproductive system infections, such as influenza A virus, influenza B virus, respiratory syncytial virus, rhinovirus, adenovirus, parainfluenza virus, coronavirus, metapneumovirus, bocavirus, human papillomavirus, mycoplasma pneumoniae, chlamydia pneumoniae, streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, gonococcus, Candida albicans, Bordetella pertussis, and Mycobacterium tuberculosis.

[0036] In some embodiments, the conjugate pad is provided with colloidal gold-labeled antibody-1 for the specific detection of pathogenic microorganisms.

[0037] In some embodiments, the nitrocellulose membrane is provided with detection lines and control lines.

[0038] In some embodiments, the detection line is provided with antibody-2 for the specific detection of pathogenic microorganisms.

[0039] In some embodiments, the specific pathogens detected by antibody-1 and antibody-2 are the same.

[0040] In some embodiments, the immunochromatographic assay kit is used to detect respiratory viruses.

[0041] In some embodiments, the immunochromatographic assay kit is used to detect the novel coronavirus.

[0042] In some embodiments, the binding pad is provided with colloidal gold-labeled antibody-1 for the specific detection of the novel coronavirus.

[0043] In some embodiments, the detection line is provided with antibody-2 for the specific detection of the novel coronavirus.

[0044] In some embodiments, the quality control line is provided with goat anti-mouse antibodies.

[0045] In some embodiments, the detection line is prepared using an antibody-2 solution with a specific detection rate of 0.5-1 mg / mL for the novel coronavirus.

[0046] In some embodiments, the quality control line is prepared using a 0.5-1 mg / mL sheep anti-mouse antibody solution.

[0047] Compared with the prior art, the beneficial effects of the present invention include at least the following aspects:

[0048] While existing technologies attempt to add additional functional substances to the sample pad processing solution to improve the sample applicability of immunochromatographic products, they still face limitations. Firstly, their ability to process special samples (such as viscous samples) is very limited. Existing immunochromatographic assay kits are still susceptible to interference from viscous samples, leading to false positives, unclean backgrounds, and other serious issues affecting result interpretation. Secondly, unlike the approach of pre-treating viscous samples, immunochromatographic products typically require a shelf life of 12 to 24 months, placing higher demands on the stability of functional substances on the sample pad. Especially for immunochromatographic products exported by sea, the impact of the high temperatures of shipping containers on the stability of the immunochromatographic products must be considered, specifically requiring the products to be stable at 55°C for at least 14 days.

[0049] The results of this invention, which uses heat preservation to infer the shelf life of immunochromatographic products at room temperature (e.g., stability at 55°C for one month is equivalent to stability at room temperature for 24 months), show that sample pad treatment solutions containing conventional functional substances (e.g., dithiothreitol, tris(2-carboxyethyl)phosphine, L-cysteine) can reduce false positives in viscous samples in the short term, but as the storage time increases (especially at higher temperatures), the functional substances in the sample pad treatment solution gradually become ineffective, and may even show no difference from the control group without added functional substances.

[0050] This invention creatively utilizes S-carboxymethyl-L-cysteine ​​as a functional ingredient in the sample pad treatment solution. It has been discovered that S-carboxymethyl-L-cysteine ​​can effectively lyse mucins and reduce sample viscosity, while significantly improving the immunochromatographic assay kit's resistance to interference with viscous samples (specifically, eliminating false positive signals and improving background in viscous samples), and preventing oxidation-induced failure of the immunochromatographic assay kit. This further ensures the long-term resistance to interference and shelf life (e.g., more than 12 months at room temperature) of the immunochromatographic assay kit for viscous samples, avoiding common problems such as tracer particle aggregation, membrane blockage, false positives, and unclean background. Furthermore, this invention also finds that the combined use of specific concentrations of S-carboxymethyl-L-cysteine ​​and Tricine buffer can synergistically enhance the immunochromatographic assay kit's resistance to interference with viscous samples, completely eliminating false positive signals while maintaining the overall effectiveness (e.g., sensitivity) and efficiency (e.g., chromatography speed) of the immunochromatographic assay kit.

[0051] Based on this, the sample pad treatment solution of the present invention can enhance the anti-interference ability of the immunochromatographic detection kit against different viscous samples (e.g., oropharyngeal swab samples, nasopharyngeal swab samples, vaginal secretion samples, sputum samples, or saliva samples) with a relatively simplified composition and extend its actual shelf life, and ensure that the detection performance and color development quality of the immunochromatographic detection kit prepared based on it remain at a high level for a long time. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. The elements or parts in the drawings are not necessarily drawn to scale. Obviously, the drawings described below are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0053] Figure 1 The image shows the test results for Example 4. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0055] In this document, the terms "upper," "lower," "inner," "outer," "front," "rear," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0056] In this document, "and / or" includes any and all combinations of one or more of the listed related items.

[0057] In this article, "multiple" means two or more, that is, it includes two, three, four, five, etc.

[0058] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0059] As used in this specification, the term "about" typically means + / -5% of the value, more typically + / -4% of the value, more typically + / -3% of the value, more typically + / -2% of the value, even more typically + / -1% of the value, and even more typically + / -0.5% of the value.

[0060] In this specification, certain embodiments may be disclosed in a range-bound format. It should be understood that this "range-bound" description is merely for convenience and brevity and should not be construed as a rigid limitation on the disclosed range. Therefore, the description of a range should be considered as having specifically disclosed all possible subranges and the individual numerical values ​​within those ranges. For example, a description of the range 1-6 should be considered as having specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and the individual numbers within those ranges, such as 1, 2, 3, 4, 5, and 6. This rule applies regardless of the breadth of the range.

[0061] Example 1

[0062] The functional substances dithiothreitol (DTT), tris(2-carboxyethyl)phosphine (TCEP), L-cysteine ​​and S-carboxymethyl-L-cysteine ​​were prepared into sample pad treatment solutions according to the formulations in Table 1. The solutions were then uniformly applied to glass fibers (200*300 mm) at a rate of 20-40 mL per sheet and dried in an oven at 37°C to prepare the sample pads.

[0063] Table 1

[0064]

[0065] The prepared sample pads are stacked with a gold pad and an NC membrane, then cut to form test strips, which are then inserted into a cartridge to form a test kit with testing function. The kits containing different sample pads are subjected to aging tests at 55℃ for 0 days, 1 week, 2 weeks, and 4 weeks. Kits aged for different times are used to test viscous oropharyngeal swab samples (samples 1-5) from healthy individuals to evaluate the effectiveness of each sample pad in treating viscous oropharyngeal swabs after different aging times.

[0066] Table 2

[0067]

[0068] Note: C1-C10 indicates the color development depth of the chromatographic test strips; the larger the number, the darker the color. A positive result is indicated when the color development depth of the T band is above C1, while "-" indicates no color development. Background evaluation criteria include: a clean sample pad background (no red) is rated "good"; a red background on the sample pad that does not affect the interpretation of the results is rated "fair"; and a red background on the sample pad that affects the interpretation of the results is rated "poor".

[0069] As shown in Table 2, although sample pads treated with L-cysteine, tris(2-carboxyethyl)phosphine, or dithiothreitol as functional substances can reduce false positive signals to some extent in the short term, they cannot completely eliminate false positive signals (this is reflected in the color depth of the T-chromogenic band being below C1). Furthermore, with prolonged storage time, the number of false positive signals on the sample pads treated with the above-mentioned sample pad solutions increases, and the background becomes increasingly unclean, severely affecting the interpretation of experimental results.

[0070] Sample pads treated with S-carboxymethyl-L-cysteine ​​as the functional ingredient exhibit superior thermal stability and better false-positive signal elimination. Furthermore, the false-positive signal elimination effect does not decrease with prolonged storage time, resulting in a longer effective shelf life (e.g., over one year). In other words, compared to L-cysteine, tris(2-carboxyethyl)phosphine, and dithiothreitol, S-carboxymethyl-L-cysteine ​​enhances the immunochromatographic assay kit's resistance to interference from viscous samples (e.g., viscous oropharyngeal swab samples) by reducing false positives, improving background cleanliness, and maintaining the sensitivity of the immunochromatographic assay kit. This may be because the introduction of carboxymethyl (-CH2COOH) at the thiol (-SH) position of L-cysteine ​​alters the chemical environment of cysteine. On the one hand, the carboxymethyl group can provide long-term protection for the thiol group in space, making it difficult for oxidants and other reactants to approach the thiol group. On the other hand, the electronic effect of the carboxymethyl group may also affect the electron cloud distribution of the thiol group, making it less likely to lose electrons and be oxidized. This ensures the stability of S-carboxymethyl-L-cysteine ​​and its long-term resistance to interference from viscous samples (such as viscous oropharyngeal swab samples).

[0071] Example 2

[0072] Prepare a COVID-19 antigen immunochromatographic assay kit according to the following protocol.

[0073] 2.1 Preparation of sample pad treatment solution and sample pad:

[0074] Prepare the sample pad treatment solution according to the formula in Table 3.

[0075] Table 3

[0076]

[0077] The prepared sample pad treatment solution was uniformly applied to each sheet of glass fiber (200*300 mm) at a rate of 20-40 mL, and then dried in an oven at 37°C to prepare the sample pad.

[0078] 2.2 Preparation of the gold-labeled pad:

[0079] Adjust the pH of the colloidal gold solution to 7.6, add the COVID-19 antigen-specific monoclonal antibody 1# to the colloidal gold solution, let stand for 10 minutes, then centrifuge to collect the precipitate, dilute it, spread it onto a glass fiber pad, and dry it in an oven at 37°C to prepare the gold-labeled pad.

[0080] 2.3 Preparation of the coating membrane:

[0081] The COVID-19 antigen-specific monoclonal antibody 2# and goat anti-mouse antibody were diluted to 0.5 mg / mL and 1 mg / mL, respectively, using coating diluent. The membrane was then etched at the T and C lines of the NC membrane using a membrane etcher and dried in an oven to prepare the coated membrane.

[0082] 2.4 The coating membrane, gold label pad, and sample pad prepared in the above steps are stacked, then cut to form test strips, which are then inserted into the cartridge to form a test kit with testing function.

[0083] The COVID-19 antigen immunochromatographic assay kits containing control sample pads, sample pad 1#, sample pad 2#, and sample pad 3# were used to test viscous oropharyngeal swab samples from 40 randomly selected healthy individuals and 3 positive quality controls. The results are shown in Tables 4-1 and 4-2.

[0084] Table 4-1

[0085]

[0086] Table 4-2

[0087]

[0088] As shown in Table 4-2, the COVID-19 antigen immunochromatographic assay kits prepared with different sample pad treatment solutions as shown in Table 3 all detected positive control samples of varying intensities well. However, as shown in Table 4-1, the test results of samples from healthy individuals revealed that the COVID-19 antigen immunochromatographic assay kit based on the control sample pad had the highest false positive rate and the background was often unclean. The COVID-19 antigen immunochromatographic assay kits using sample pads with S-carboxymethyl-L-cysteine ​​as the functional substance (e.g., sample pad 1#, sample pad 2#) showed a significant reduction in false positive results. When S-carboxymethyl-L-cysteine ​​was used in combination with Tricine buffer (i.e., sample pad 3#), the false positive result of the COVID-19 antigen immunochromatographic assay kit decreased to 0, meaning the false positive signal was completely eliminated, and the cleanliness of the background was significantly improved.

[0089] Example 3

[0090] Prepare the COVID-19 antigen immunochromatographic assay kit according to the following protocol (the method is the same as in Example 2).

[0091] Preparation Example 1: The sample pad treatment solution consists of: 25mM Tricine buffer, 150mM NaCl, 0.2% Triton X-100, 0.1% S-carboxymethyl-L-cysteine, 0.5% BSA, 0.05% Proclin 300, pH 7.6.

[0092] Preparation Example 2: The difference between this preparation example and Preparation Example 1 is that 50mM PB buffer was used.

[0093] Preparation Example 3: The difference between this preparation example and Preparation Example 1 is that 50mM borate buffer was used.

[0094] Preparation Example 4: The difference between this preparation example and Preparation Example 1 is that 5% S-carboxymethyl-L-cysteine ​​was used.

[0095] Preparation Example 5: The difference between this preparation example and Preparation Example 1 is that 200mM Tricine buffer was used.

[0096] Comparative Example 1: The difference between this comparative example and Preparation Example 1 is that S-carboxymethyl-L-cysteine ​​is not used.

[0097] Comparative Example 2: The difference between this comparative example and Preparation Example 1 is that 6% S-carboxymethyl-L-cysteine ​​was used.

[0098] The COVID-19 antigen immunochromatographic assay kits prepared using the sample pads prepared according to the above scheme were used to test viscous oropharyngeal swab samples from 4 healthy individuals and 1 positive quality control sample. The results are shown in Table 5.

[0099] Table 5

[0100]

[0101] The results of Comparative Example 1 show that, without the addition of S-carboxymethyl-L-cysteine, viscous oropharyngeal swab samples 1#-4# produced varying degrees of false positive signals and had unclean backgrounds, severely affecting the interpretation of the results. Preparation Example 1, however, demonstrates that adding 0.1% S-carboxymethyl-L-cysteine ​​significantly improved the anti-interference ability of the immunochromatographic assay kit, eliminating false positive signals in viscous oropharyngeal swab samples 1#-4# and significantly improving the background.

[0102] As can be seen from Preparation Examples 1, 2, and 3, when the sample pad treatment solution uses 25 mM Tricine as the buffer, its combination with 0.1% S-carboxymethyl-L-cysteine ​​can further enhance the anti-interference ability of the immunochromatographic assay kit. As can be seen from Preparation Examples 1 and 5, using 50 mM-200 mM Tricine as the buffer and combining it with S-carboxymethyl-L-cysteine ​​can enhance the anti-interference ability of the immunochromatographic assay kit and completely eliminate false positive signals.

[0103] As can be seen from Preparation Examples 1 and 4 and Comparative Example 2, when the concentration of S-carboxymethyl-L-cysteine ​​in the sample pad treatment solution exceeds 5%, the anti-interference ability of the immunochromatographic assay kit does not decrease. However, the slight decrease in the intensity of the T-band during positive control detection indicates that a high concentration of S-carboxymethyl-L-cysteine ​​in the sample pad treatment solution may lead to a slight decrease in the sensitivity of the immunochromatographic assay kit (a concentration of Tricine above 200 mM may also lead to the above result).

[0104] Example 4

[0105] Prepare the sample pad treatment solution according to the following formula. Evenly wet and coat each sheet of glass fiber (200*300 mm) with the solution at a rate of 20-40 mL, and dry in an oven at 37°C to prepare the sample pad. The sample pad treatment solution consists of: 50 mM Tricine buffer, 150 mM NaCl, 0.2% Triton X-100, 2% S-carboxymethyl-L-cysteine, 0.5% BSA, 0.05% Proclin 300, pH 7.6.

[0106] The prepared sample pad, gold pad, and NC membrane were stacked, then cut to form test strips, which were then inserted into a cartridge to create a test kit with diagnostic functionality. The kit was used to test viscous nasopharyngeal swab samples from five healthy individuals, and the results are as follows: Figure 1 As shown.

[0107] from Figure 1 The results on the left show that viscous nasopharyngeal swab samples produce varying degrees of false positive signals and have unclean backgrounds, severely affecting the interpretation of the results. The sample pad treatment solution of this invention significantly enhances the anti-interference ability of the immunochromatographic detection kit, completely eliminating false positive signals in viscous nasopharyngeal swab samples 1#-5# and significantly improving the background.

[0108] The results above show that the sample pad treatment solution of the present invention enhances the anti-interference ability of the immunochromatographic assay kit, making it suitable for the detection of different viscous samples while maintaining a high level of sensitivity.

[0109] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A sample pad, characterized in that, The sample pad is obtained by treating it with a sample pad treatment solution, which includes at least the following components: S-carboxymethyl-L-cysteine, buffer solution, neutral inorganic salt, surfactant, and blocking agent. The mass fraction of S-carboxymethyl-L-cysteine ​​is 0.1%-5%, the buffer solution is tris(hydroxymethyl)methylglycine buffer solution, and the concentration of the buffer solution is 25mM-200mM. The concentration of the neutral inorganic salt is 25-200 mM. The treatment method specifically includes: wetting and / or coating a glass fiber membrane with the sample pad treatment solution, and then drying the glass fiber membrane to obtain the sample pad.

2. The sample pad as described in claim 1, characterized in that, The pH of the sample pad treatment solution ranges from 7.6 to 8.

4.

3. The sample pad as described in claim 1, characterized in that, The surfactant includes one or more of Triton X-100, Tween20, Tween80, S9, NP-40, and CHAPS; the mass fraction of the surfactant may optionally include 0.1-5.0%.

4. The sample pad as described in claim 1, characterized in that, The sealing agent includes one or more of BSA, CASEIN, CASEIN-Na, gelatin, and skim milk powder; the mass fraction of the sealing agent may optionally include 0.1-5.0%.

5. The sample pad as described in claim 1, characterized in that, The sample pad treatment solution comprises the following components: 25mM-200mM buffer solution, 0.1%-5% (mass fraction) S-carboxymethyl-L-cysteine, 25-200 mM neutral inorganic salt, 0.1-5.0% (mass fraction) surfactant, 0.1-5% (mass fraction) blocking agent, and 0.02-0.2% (mass fraction) preservative.

6. An immunochromatographic assay kit for detecting viscous samples, characterized in that, The immunochromatographic assay kit includes a test strip, which includes a base plate, a sample pad, a conjugate pad, a nitrocellulose membrane, and an absorbent pad, which are sequentially overlapped on the base plate as described in any one of claims 1-5.

7. The kit according to claim 6, characterized in that, The conjugate pad is provided with colloidal gold-labeled antibody-1 for the specific detection of pathogenic microorganisms, and the nitrocellulose membrane is provided with detection lines and control lines.

8. The reagent kit as described in claim 6, characterized in that, The viscous samples include oropharyngeal swab samples, nasopharyngeal swab samples, vaginal secretion samples, sputum samples, or saliva samples.

9. The use of a sample pad treatment solution in the preparation of an immunochromatographic assay kit for detecting viscous samples, characterized in that, The immunochromatographic assay kit includes a test strip, which comprises a base plate, a sample pad, a conjugate pad, a nitrocellulose membrane, and an absorbent pad sequentially overlapped on the base plate. The sample pad is obtained by treating it with a sample pad treatment solution. The sample pad treatment solution comprises at least the following components: S-carboxymethyl-L-cysteine, buffer solution, neutral inorganic salt, surfactant, and blocking agent. The mass fraction of S-carboxymethyl-L-cysteine ​​is 0.1%-5%, the buffer solution is tris(hydroxymethyl)methylglycine buffer, and the concentration of the buffer solution is 25mM-200mM. The concentration of the neutral inorganic salt is 25-200mM. The treatment method specifically includes: wetting and / or coating the glass fiber membrane with the sample pad treatment solution, and then drying the glass fiber membrane to obtain the sample pad.

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