Gold nanoprobe for detecting SARS-COV-2 antigen, preparation method therefor, and use thereof

Abstract

A gold nanoprobe for detecting a SARS-CoV-2 antigen, a preparation method therefor, and a use thereof. The preparation method comprises the following steps: S1: mixing an HAuCl4 solution boiling at standard atmospheric pressure with a sodium citrate solution, and fully reacting until the mixture becomes red to obtain gold nanospheres; S2: mixing the gold nanospheres, the HAuCl4 solution, and the sodium citrate of step S1 with hydroquinone, and fully reacting to obtain gold nanoflowers; and S3: mixing a SARS-COV-2 monoclonal antibody with the gold nanoflowers of step S2, and fully reacting to obtain gold nanoprobes. The gold nanoflowers thus prepared have a particle size of 55-75 nm, a high specific surface area, and a high extinction coefficient, thus forming a higher contrast. The gold nanoflowers and the monoclonal antibody for specifically recognizing the SARS-CoV-2 N antigen form the gold nanoprobes by means of electrostatic adsorption, thereby improving the sensitivity of test paper.

Description

A gold nanoprobe for detecting novel coronavirus antigens, and its preparation method and application Technical Field

[0001] The present invention relates to the field of biological detection technology, and specifically to a gold nanoprobe for detecting novel coronavirus antigens, and a preparation method and application thereof. Background Art

[0002] Modern healthcare systems have achieved remarkable success in preventing and controlling the novel coronavirus. Universal testing and quarantine measures have effectively blocked the virus's transmission pathways, with a key step being the use of in vitro diagnostic technology to screen for pathogen carriers. Colloidal gold immunoassays offer valuable applications in the face of the rapidly spreading novel coronavirus. While their advantages are rapid detection and ease of use, they also suffer from insufficient sensitivity, making it difficult to generate positive results when testing samples with low virus concentrations. Therefore, improving detection sensitivity is a key area for advancement and breakthroughs in colloidal gold immunoassay technology.

[0003] In colloidal gold immunoassay technology, sensitization can be achieved by screening antibodies with higher affinity, adjusting the production process for a better result, or using colorimetric reagents. Screening antibodies can improve detection sensitivity, but the investment cost and time are high, and the resulting antibodies have a narrow range of applications. Optimization of the process flow often has limited effects, and the resulting process methods are also not widely applicable. Auxiliary colorimetric reagents for sensitization may require storage conditions at low temperatures and away from light, and some components are toxic, in addition to increased costs and the cumbersome process of additional modification of colloidal gold.

[0004] Currently, there are also colloidal gold test strips that use gold nanoflowers to detect the new coronavirus. This test strip has the following disadvantages: (1) The preparation of gold nanoflowers requires strict temperature control, which has high requirements for experimental conditions; (2) The colloidal gold-labeled antibodies used need to be coupled with streptavidin and biotin to improve the affinity for the antibodies. The gold-labeled antibodies also need to be dialyzed and purified by column, and the preparation method is complicated and tedious; (3) The material requirements for the nitrocellulose membrane are high, and the nanocellulose gel needs to be pre-coated near the detection line to further amplify the detection signal. (4) The sensitivity is low, with a minimum detection limit of 2.0×10 2 TCID 50 / mL, it cannot distinguish lower concentrations of new coronavirus samples and is difficult to meet market demand.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and provide a gold nanoprobe for detecting novel coronavirus antigens, as well as a preparation method and application thereof.

[0007] The first object of the present invention is to provide a method for preparing a gold nanoprobe for detecting novel coronavirus antigens.

[0008] The second object of the present invention is to provide a gold nanoprobe prepared by the preparation method.

[0009] The third object of the present invention is to provide the use of the gold nanoprobe in the preparation of products for detecting new coronavirus antigens.

[0010] The fourth object of the present invention is to provide a test strip for detecting novel coronavirus antigens.

[0011] The fifth object of the present invention is to provide the use of the test strip in the preparation of a kit for detecting new coronavirus antigens.

[0012] The sixth object of the present invention is to provide a kit for detecting novel coronavirus antigens.

[0013] In order to achieve the above object, the present invention is implemented through the following scheme:

[0014] A method for preparing a gold nanoprobe for detecting novel coronavirus antigens comprises the following steps:

[0015] S1: Mix HAuCl4 solution boiling under standard atmospheric pressure with sodium citrate solution and allow to react fully until it turns red to obtain gold nanospheres;

[0016] S2: Mix the gold nanospheres, HAuCl4 solution, sodium citrate and hydroquinone prepared in step S1 and allow them to react fully to obtain gold nanoflowers;

[0017] S3: Mix the SARS-CoV-2 monoclonal antibody with the gold nanoflowers from step S2 and allow them to react fully to obtain gold nanoprobes.

[0018] Preferably, in step S1, the mass ratio of HAuCl4 to sodium citrate is 10:7-50.

[0019] More preferably, in step S1, the mass ratio of HAuCl4 to sodium citrate is 10:27.

[0020] Preferably, in step S2, the mass ratio of gold nanospheres to HAuCl4 is 1:129-259.

[0021] More preferably, in step S2, the mass ratio of gold nanospheres to HAuCl4 is 1:129.

[0022] Preferably, in step S3, the novel coronavirus monoclonal antibody is a novel coronavirus N protein monoclonal antibody.

[0023] More preferably, the SARS-CoV-2 N protein monoclonal antibody is the commercially available SC2N-118 antibody.

[0024] More preferably, the pH of the gold nanoflowers in step S2 is adjusted to 8.5-10.0, mixed with the SC2N-118 antibody, fully reacted, blocked with casein, and then solid-liquid separated to obtain the gold nanoprobe.

[0025] More preferably, the mass ratio of gold nanoflowers to SC2N-118 antibody is 100:11-46.

[0026] More preferably, the mass ratio of gold nanoflowers to SC2N-118 antibody is 100:23.

[0027] More preferably, the reaction time is 13 to 17 minutes.

[0028] More preferably, the reaction time is 15 min.

[0029] More preferably, the solid-liquid separation is carried out by centrifugation at 0-4°C and 5500-6500g for 13-17 minutes.

[0030] More preferably, the solid-liquid separation is performed by centrifugation at 4°C and 6000g for 15 min.

[0031] The gold nanoprobe prepared by the preparation method.

[0032] The use of the gold nanoprobe in the preparation of products for detecting novel coronavirus antigens.

[0033] A test strip for detecting novel coronavirus antigens, wherein the conjugate pad of the test strip is coated with the gold nanoprobe.

[0034] Preferably, the coating concentration of the gold nanoprobe is 0.76-3.04 mg / mL.

[0035] More preferably, the coating concentration of the gold nanoprobe is 3.04 mg / mL.

[0036] More preferably, the gold nanoprobe is redissolved in a redissolving solution and then coated on the test strip, wherein the redissolving solution is a borate buffer solution containing 0.9-1.1% (w / v) BSA, 2.9-3.1% (w / v) sucrose and 0.04-0.06% (w / v) sodium azide at a concentration of 10 mM and a pH of 7.4.

[0037] More preferably, the reconstitution solution is a borate buffer solution containing 1% (w / v) BSA, 3% (w / v) sucrose and 0.05% (w / v) sodium azide with a concentration of 10 mM and a pH of 7.4.

[0038] Preferably, the detection area of ​​the test strip is coated with monoclonal antibodies against the new coronavirus.

[0039] More preferably, the coating amount of the novel coronavirus monoclonal antibody is 1.4-1.6 mg / mL.

[0040] More preferably, the coating amount of the novel coronavirus monoclonal antibody is 1.5 mg / mL.

[0041] More preferably, the novel coronavirus monoclonal antibody is a novel coronavirus N protein monoclonal antibody.

[0042] More preferably, the novel coronavirus monoclonal antibody is the commercially available SC2N-113 antibody.

[0043] Preferably, the quality control area of ​​the test strip is coated with goat anti-rabbit polyclonal antibodies.

[0044] More preferably, the coating amount of the goat anti-rabbit polyclonal antibody is 0.9-1.1 mg / mL.

[0045] More preferably, the coating amount of the goat anti-rabbit polyclonal antibody is 1 mg / mL.

[0046] Preferably, the sample pad of the test strip is obtained by soaking in a sample treatment solution, and the sample treatment solution consists of an aqueous solution of 5.9-6.1% (w / v) sucrose, 1.9-2.1% (w / v) trehalose, 0.09-0.11% (v / v) Tween-20 and 0.4-0.6% (w / v) BSA.

[0047] More preferably, the sample treatment solution consists of an aqueous solution of 6% (w / v) sucrose, 2% (w / v) trehalose, 0.1% (v / v) Tween-20 and 0.5% (w / v) BSA.

[0048] The use of the test strip in the preparation of a kit for detecting novel coronavirus antigens.

[0049] A kit for detecting novel coronavirus antigens, comprising the test strip.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] (1) The gold nanoflowers used in the present invention do not require strict temperature control, and the preparation method is simple and easy to operate. The experimental conditions are not high.

[0052] (2) The immune probe in the novel coronavirus antigen test paper is formed by electrostatic adsorption of gold nanoflowers and monoclonal antibodies that specifically recognize the novel coronavirus N antigen, and has higher detection sensitivity than using gold nanospheres.

[0053] (3) The gold nanoflowers prepared by the present invention have a particle size of 55 to 75 nm, a high specific surface area and a high extinction coefficient, which makes the detection line appear purple-black and can form a higher contrast relative to the nitrocellulose membrane in the background.

[0054] (4) The immune probe prepared by the gold nanoflowers in the present invention further improved the detection sensitivity and achieved effective detection of the new coronavirus pseudovirus sample (Brazilian strain, about 7.8125TCID) diluted 128,000 times 50 / mL), and the method is simple and easy, suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 shows the assembled colloidal gold immunochromatographic test strip.

[0056] Figure 2 shows the color development of the negative control test strip.

[0057] Figure 3 shows the color development of the test strip of the new coronavirus pseudovirus sample after being diluted 16,000 times.

[0058] Figure 4 shows the color development of the test strip of the new coronavirus pseudovirus sample after being diluted 32,000 times.

[0059] Figure 5 shows the color development of the test strip of the new coronavirus pseudovirus sample after being diluted 64,000 times.

[0060] Figure 6 shows the color development of the test strip of the new coronavirus pseudovirus sample after being diluted 12,800 times. DETAILED DESCRIPTION

[0061] The present invention is further described in detail below with reference to the accompanying drawings and specific examples. The examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods used in the following examples are conventional methods unless otherwise specified; the materials and reagents used are commercially available unless otherwise specified.

[0062] SC2N-118 and SC2N-113 antibodies were purchased from Hangzhou Boyue Biotechnology Co., Ltd.

[0063] Example 1 Preparation of gold nanoflowers

[0064] The synthesis of gold nanoflowers using the seed growth method is divided into two steps: preparing gold seeds (gold nanospheres) and generating nanoflowers.

[0065] 1. Preparation of gold seeds

[0066] Scheme (1): 100 mL of 0.01% (w / v) HAuCl4 solution was heated to boiling (100-101 kPa) under vigorous stirring (400-800 rpm), and 2.7 mL of 1% (w / v) sodium citrate aqueous solution was added. After the solution turned red, it was heated and boiled for 10 minutes to obtain gold seeds with a particle size of 20 nm.

[0067] Scheme (2): The amount of 1% (w / v) sodium citrate aqueous solution used was 0.7 mL, and the other reaction parameters were the same as those of scheme (1) for preparing gold seeds.

[0068] Scheme (3): The amount of 1% (w / v) sodium citrate aqueous solution used was 5 mL, and the other reaction parameters were the same as those of scheme (1) for preparing gold seeds.

[0069] 2. Preparation of gold nanoflowers with a particle size of 55 nm:

[0070] Take 100 mL of ultrapure water, add 750 μL of 1% (w / v) HAuCl4 solution, 1 mL of gold seeds with a particle size of 20 nm synthesized in scheme (1), 220 μL of 1% (w / v) sodium citrate and 1 mL of 30 mM hydroquinone in sequence at room temperature (20-26°C) and vigorous stirring (400-800 rpm), and continue stirring and reacting for 30 minutes to obtain gold nanoflowers with a particle size of 55 nm.

[0071] 3. The steps for preparing gold nanoflowers with a particle size of 75 nm are as follows:

[0072] Take 100 mL of ultrapure water, add 750 μL of 1% (w / v) HAuCl4 solution, 0.5 mL of gold seeds with a particle size of 20 nm synthesized in scheme (1), 220 μL of 1% (w / v) sodium citrate and 1 mL of 30 mM hydroquinone in sequence at room temperature (20-26°C) and vigorous stirring (400-800 rpm), continue stirring and reacting for 30 minutes to obtain gold nanoflowers with a particle size of 75 nm.

[0073] Example 2 Gold nanoprobes and binding pads prepared under different conditions

[0074] 1. Preparation of gold nanoprobes

[0075] 1. Experimental Group 1:

[0076] (1) Take 1 mL of the 55 nm gold nanoflowers prepared in Example 1 and place them in a 1.5 mL centrifuge tube. Add 10 μL of 0.2 M K2CO3 and rotate and mix at room temperature (20-26°C) for 10 min to obtain gold nanoflowers with a pH of 9.0.

[0077] (2) Mix the gold nanoflowers with pH 9.0 in step (1) and 10 μg of monoclonal antibody SC2N-118 (concentration 2 mg / mL, dosage 5 μL), rotate and mix at room temperature (20-26°C) for 15 minutes to obtain gold nanoflowers labeled with monoclonal antibody SC2N-118.

[0078] (3) Mix the gold nanoflowers labeled with the monoclonal antibody SC2N-118 from step (2) and 50 μL of 1% (w / v) casein solution, and rotate and mix at room temperature (20-26°C) for 15 minutes to block the excess binding sites on the gold nanoflowers and the labeled monoclonal antibody SC2N-118, thereby obtaining the blocked gold nanoflowers labeled with the monoclonal antibody SC2N-118.

[0079] (4) The gold nanoflowers labeled with the monoclonal antibody SC2N-118 after blocking in step (3) were centrifuged at 4°C, 6000g for 15 min, the supernatant was discarded, mixed with 100 μL of the reconstitution solution and gently blown to redissolve to obtain a 0.76 mg / mL gold nanoprobe reconstitution solution, which was stored at 4°C for later use; the reconstitution solution consisted of 1% (w / v) BSA, 3% (w / v) sucrose and 0.05% (w / v) sodium azide in borate buffer (10 mM, pH 7.4).

[0080] (5) The gold nanoprobe complex solution from step (4) was evenly sprayed onto an 8 mm wide glass fiber membrane at a spraying rate of 5 μL / cm to obtain a glass fiber membrane sprayed with gold nanoprobes. The glass fiber membrane sprayed with gold nanoprobes was dried in an oven at 37°C for 12-16 hours to obtain a conjugate pad.

[0081] 2. Experimental Group 2:

[0082] The amount of the reconstitution solution used was 25 μL, and a 3.04 mg / mL gold nanoprobe reconstitution solution was obtained. Other preparation methods were the same as those of experimental group 1.

[0083] 3. Experimental Group 3:

[0084] The gold nanoflowers were the 75 nm gold nanoflowers prepared in Example 1, and the other preparation methods were the same as those in Experimental Group 1.

[0085] 4. Experimental Group 4:

[0086] The gold nanoflowers were the 75 nm gold nanoflowers prepared in Example 1. The amount of the reconstitution solution was 25 μL, and a 3.04 mg / mL gold nanoprobe reconstitution solution was obtained. The other preparation methods were the same as those of Experimental Group 1.

[0087] 5. Experimental Group 5:

[0088] The dosage of monoclonal antibody SC2N-118 was set to 5 μg, and other preparation methods were the same as those of experimental group 4.

[0089] 6. Experimental Group 6:

[0090] The dosage of monoclonal antibody SC2N-118 was set to 20 μg, and other preparation methods were the same as those of experimental group 4.

[0091] 7. Control group:

[0092] (1) The 55 nm gold nanoflowers were replaced with gold nanospheres, and the amount of the reconstitution solution was 100 μL to obtain a 1 mg / mL gold nanoprobe reconstitution solution. The other preparation methods were the same as those of experimental group 1.

[0093] Example 3 Preparation of colloidal gold immunochromatographic test strips for detecting novel coronavirus and testing their sensitivity

[0094] 1. Experimental Methods

[0095] 1. Preparation method

[0096] (1) Preparation of conjugate pad: The resuspended gold nanoprobes from Experimental Groups 1 to 4 and the control group of Example 2 were uniformly sprayed onto an 8 mm wide glass fiber membrane using a gold spraying apparatus at a spraying rate of 5 μL / cm to obtain a glass fiber membrane sprayed with gold nanoprobes. The glass fiber membrane sprayed with gold nanoprobes was dried in a 37°C oven for 12 to 16 hours to obtain a conjugate pad.

[0097] (2) Preparation of sample pad: Soak an 18 mm wide glass fiber membrane in a sample treatment solution for 1 hour to obtain a sample treatment solution-soaked glass fiber membrane. Dry the sample treatment solution-soaked glass fiber membrane in a 50°C oven for 10 hours to obtain a sample pad. The sample treatment solution consists of an aqueous solution of 6% (w / v) sucrose, 2% (w / v) trehalose, 0.1% (v / v) Tween-20, and 0.5% (w / v) BSA.

[0098] (3) Preparation of antibody-coated nitrocellulose membrane: Use a PVC base plate with self-adhesive tape (upper 15 mm + middle 25 mm + lower 20 mm) and stick a 25 cm wide nitrocellulose membrane (flow rate 130 s) in the middle of the PVC base plate.

[0099] Dilute goat anti-rabbit polyclonal antibody to 1 mg / mL with Antibody Diluent 1. Streak the control line (C line) of the nitrocellulose membrane with 1 mg / mL goat anti-rabbit polyclonal antibody at a rate of 1 mL / cm using a streak meter. Dilute SC2N-113 monoclonal antibody to 1.5 mg / mL with Antibody Diluent 2. Streak the test line (T line) of the nitrocellulose membrane with 1.5 mg / mL SC2N-113 monoclonal antibody at a rate of 1 μL / cm using a streak meter to obtain a streaked nitrocellulose membrane.

[0100] The nitrocellulose membrane with the lines was placed in an oven at 50°C and dried for 10 hours to obtain a PVC base plate with the antibody-coated nitrocellulose membrane.

[0101] Antibody diluent 1 consisted of 1% (w / v) sucrose, 0.3% (w / v) trehalose, 1% (v / v) methanol, and 0.01% (w / v) PEG20000 in PBS (10 mM, pH 7.4). Antibody diluent 2 consisted of 3% (w / v) sucrose, 1% (w / v) trehalose, 3% (v / v) methanol, and 0.05% (w / v) PEG20000 in PBS (10 mM, pH 7.4).

[0102] (4) Assembling colloidal gold immunochromatographic test strips: As shown in Figure 1, absorbent paper (i.e., absorbent pad), nitrocellulose membrane, conjugate pad, and sample pad are sequentially attached to the PVC base plate, with each part overlapping by 1 to 2 mm. Among them, the quality control line (C line) is on the side close to the absorbent pad, and the detection line (T line) is on the side close to the conjugate pad. According to the above steps, a PVC base plate with a nitrocellulose membrane coated with an antibody is prepared. One end of the PVC base plate is stacked with absorbent paper, and the other end is stacked with a conjugate pad and a sample pad in sequence, wherein the conjugate pad is between the nitrocellulose membrane and the sample pad. The test strip is cut into 3 mm widths.

[0103] By the above method, a colloidal gold immunochromatographic test strip for the new coronavirus was prepared using the resuspended gold nanoprobes of experimental groups 1 to 4 and the control group in Example 2.

[0104] 2. Sample determination method: Dilute the new coronavirus positive reference (Brazilian strain, 10 6 TCID 50 / mL, purchased from Nanjing Baikang Biotechnology Co., Ltd.), using the sample diluent as a negative control, a two-fold dilution method was used for gradient dilution, with dilutions of 16,000-fold, 32,000-fold, 64,000-fold, and 128,000-fold, respectively. 50 μL of the diluted sample was added to the sample pad of different colloidal gold immunochromatographic test strips and allowed to stand for 15-30 minutes. The test results were directly interpreted or photographed and recorded. The sample diluent was a 20 mM boric acid solution containing 0.1% (v / v) Tween-20 and 0.05% (v / v) ProClin-300, pH 7.4.

[0105] 3. Interpretation method: If the quality control line (C line) does not show color, it is an invalid test result; if the quality control line (C line) shows color and the test line (T line) shows color, it is a positive result; if the quality control line (C line) shows color and the test line (T line) does not show color, it is a negative result.

[0106] 2. Experimental Results

[0107] As shown in Table 1, the test strip prepared with the gold nanoflowers in Experimental Group 4 of Example 2 can still clearly display and detect the novel coronavirus pseudovirus sample (Brazilian strain, 7.8125 TCID) diluted 128,000 times. 50 / mL).

[0108] The color development of the negative control test strip is shown in Figure 2. The new coronavirus pseudovirus sample (Brazilian strain, 62.5TCID 50 The color development of the test strip (10000 times diluted 1000 times) is shown in Figure 3. The new coronavirus pseudovirus sample (Brazilian strain, 31.25TCID 50 The color development of the test strip (10000 times diluted 1000 times) is shown in Figure 4. The new coronavirus pseudovirus sample (Brazilian strain, 15.625TCID 50 The color development of the test strip ( / mL) is shown in Figure 5. The new coronavirus pseudovirus sample (Brazilian strain, 7.8125TCID) after 128,000-fold dilution 50 The color development of the test strip (100 μg / mL) is shown in Figure 6. In Example 2, experimental groups 1 and 3, while using lower amounts of gold nanoprobes than the control group, exhibited superior detection line intensity and sensitivity. Increasing the gold nanoflower probe dosage by fourfold increased sensitivity by a further twofold compared to the original dosage, with no false positives. The specific test results are summarized in Table 1.

[0109] The above results show that the colloidal gold immunochromatographic test strips for detecting the new coronavirus prepared with the gold nanoflowers of Example 1 have high sensitivity, and the detection line is purple-black, which can produce a stronger visual contrast with the white nitrocellulose membrane background. Among them, the test strips prepared with 75nm gold nanoflowers can effectively detect the new coronavirus pseudovirus sample (Brazilian strain, about 7.8125TCID) diluted 128,000 times. 50 / mL), showing a clear weak positive.

[0110] Table 1 Sensitivity test Note: “-” indicates negative; “- / +” indicates the T line is sometimes present and sometimes absent; “+” indicates a clear weak positive; “++” indicates a positive; “+++” indicates a strong positive.

[0111] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art will readily appreciate that other variations or modifications may be made based on the above descriptions and concepts. It is not necessary and impossible to provide an exhaustive list of all possible implementations. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a gold nanoprobe for detecting novel coronavirus antigens, characterized in that: The following steps are involved: S1: Mix the boiling HAuCl4 solution under standard atmospheric pressure with the sodium citrate solution and allow them to react fully until they turn red to obtain gold nanospheres; S2: mixing the gold nanospheres, HAuCl4 solution, sodium citrate and hydroquinone prepared in step S1 and reacting them sufficiently to obtain gold nanoflowers; S3: Mix the monoclonal antibody of the new coronavirus with the gold nanoflowers from step S2 and allow them to react fully to obtain gold nanoprobes.

2. The preparation method according to claim 1, characterized in that: In step S1, the mass ratio of HAuCl4 to sodium citrate is 10:7-50.

3. The preparation method according to claim 1, characterized in that: In step S2, the mass ratio of gold nanospheres to HAuCl4 is 1:129-259.

4. The preparation method according to claim 1, characterized in that: In step S3, the SARS-CoV-2 monoclonal antibody is a SARS-CoV-2 N protein monoclonal antibody.

5. The gold nanoprobe prepared by the preparation method according to any one of claims 1 to 4.

6. Use of the gold nanoprobe described in claim 5 in the preparation of products for detecting new coronavirus antigens.

7. A test strip for detecting novel coronavirus antigen, characterized in that: The conjugate pad of the test strip is coated with the gold nanoprobe according to claim 5.

8. The test strip according to claim 7, characterized in that: The coating concentration of the gold nanoprobe is 0.76-3.04 mg / mL.

9. Use of the test strip according to claim 7 in preparing a kit for detecting novel coronavirus antigens.

10. A kit for detecting novel coronavirus antigens, characterized in that: The kit comprises the test strip according to claim 7.

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