Nitrocellulose membrane with backing as well as preparation method and application of nitrocellulose membrane

Abstract

The invention provides a nitrocellulose membrane with a backing as well as a preparation method and application of the nitrocellulose membrane, and belongs to the technical field of high polymer materials. The preparation method of the nitrocellulose membrane with the backing comprises the following steps: S10, dissolving nitrocellulose, a pore-foaming agent and a hydrophilic polymer in DMF (Dimethyl Formamide) and / or DMA (Dimethyl Formamide), and filtering and degassing to obtain a uniform and stable nitrocellulose membrane casting solution; s20, the nitrocellulose membrane casting solution is subjected to membrane scraping forming on a backing made of a PVC material, and a precursor membrane is obtained; s30, performing phase splitting on the precursor film in a solution to obtain a semi-wet film; and S40, washing and drying the semi-wet membrane to obtain the nitrocellulose membrane with the backing. The nitrocellulose membrane with the backing has the characteristics of uniform and controllable aperture, good hydrophilicity, strong protein binding capacity, large-scale production and the like, and has a wide application prospect in the field of in-vitro diagnostic reagents.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a nitrocellulose membrane with a backing, a preparation method and an application thereof. Background Art

[0002] Nitrocellulose Membrane (also known as NC membrane) is a type of functional membrane material with cellulose derivative nitrocellulose as the main material. Since the nitrate group on nitrocellulose has a strong dipole property and has a strong non-specific adsorption effect on macromolecules such as proteins, it can efficiently fix biological molecules. Therefore, NC membrane is used as a solid phase carrier and plays an important role in the field of colloidal gold immunochromatography detection. In addition, NC membrane can also be used in molecular biology and biochemistry fields such as cell culture, biosensors, molecular hybridization and immunoblotting.

[0003] The preparation process of nitrocellulose membrane is mainly as follows: first, dissolve nitrocellulose particles in an organic solvent, add a certain proportion of surfactant, stir and configure into a uniform casting liquid; then the casting liquid passes through a roller to form a thin film and spread it on a flat carrier; dry and shape it through a certain process; finally harvest and cut to obtain a nitrocellulose membrane product. Patent CN114768545A discloses a nitrocellulose microporous membrane and a continuous preparation method thereof. Using a simple conventional process, a protein adsorbent with good compatibility with nitrocellulose is added during the preparation of the casting liquid to prepare an NC membrane with good protein binding ability. Patent CN114130373A discloses a nitrocellulose membrane and a preparation method thereof. Using a simple conventional process, a hydrotalcite with a special layered structure is added during the preparation of the casting liquid to prepare an NC membrane with a multi-aperture support layer structure. Patent CN113150334A discloses a nitrocellulose membrane preparation process. In the preparation process, by improving the surfactant treatment process, the influence of bubbles and impurities on the NC membrane during the production process is reduced, thereby preparing a NC membrane with higher quality. As the main component of immunochromatography, NC membrane is not only the solid support carrier of the test line T line and the control line C line, but also the area where antigens and antibodies react. Its quality directly affects the performance indicators of in vitro diagnostic reagents. The methods for detecting the quality of NC membranes include "water soaking performance" and "spot test", and the test results are related to the pore size and hydrophilicity of the membrane. The membrane with a small pore size has a large specific surface area, a large amount of bound protein, and a slow chromatography speed. The gold-labeled complex takes a long time to pass through the T line, the reaction is sufficient, and the sensitivity is high. But at the same time, the membrane with a small pore size has a slow plate running speed, a high chance of non-specific binding, and is prone to false positives. Therefore, NC membranes with appropriate pore sizes are required for the detection of different test objects.

[0004] Nitrocellulose membrane is a kind of cellulose derivative. It has a certain hydrophilicity but it is not good. It needs to be improved by treating with surfactants during the preparation process. However, surfactants are small molecules and will be lost during the storage of NC membranes, resulting in reduced hydrophilicity and uneven hydrophilicity of NC membranes. Moreover, surfactant solutions are prone to bubbles, which will accumulate on the surface of NC membranes during continuous production, affecting the quality of NC membranes. Therefore, in order to obtain NC membranes with stable quality and controllable pore size, it is necessary to improve the preparation process of NC membranes to achieve the adjustment of pore size and hydrophilicity of NC membranes during the preparation process. Summary of the invention

[0005] The present invention is made to solve the above problems, and aims to provide a nitrocellulose membrane with backing and a preparation method and application thereof.

[0006] The invention provides a method for preparing a nitrocellulose membrane with a backing, which has the following characteristics and comprises the following steps: S10, dissolving nitrocellulose, a porogen and a hydrophilic polymer in DMF and / or DMAC according to (10-50) wt%: (1-30) wt%: (1-15) wt% and filtering and degassing to obtain a uniform and stable nitrocellulose membrane casting solution, wherein the porogen comprises polyvinyl pyrrolidone and / or polyethylene glycol, and the hydrophilic polymer comprises sulfonated polyether sulfone, polyaniline or polyacrylamide. Any one or more; S20, scraping the nitrocellulose casting liquid on a PVC backing with a thickness of 0.06mm to 0.10mm to form a film to obtain a precursor film; S30, phase-separating the precursor film in the solution to obtain a semi-wet film; S40, washing and drying the semi-wet film to obtain a nitrocellulose membrane with a backing, wherein the nitrocellulose membrane with a backing is a microporous membrane, and the micropore size of the nitrocellulose membrane with a backing can be controlled by adjusting the amount of the porogen, and the hydrophilic property of the nitrocellulose membrane with a backing can be controlled by adjusting the amount of the hydrophilic polymer.

[0007] The method for preparing the nitrocellulose membrane with backing provided by the present invention may also have the following characteristics: wherein, in step S10, the degassing treatment method is to stand for more than 4 hours for degassing.

[0008] The method for preparing the nitrocellulose membrane with backing provided by the present invention may also have the following characteristics: wherein, in step S20, the tool used for film scraping is a scraper with a film scraping thickness of 0.38 mm.

[0009] The method for preparing the nitrocellulose membrane with backing provided by the present invention may also have the following characteristics: wherein, in step S30, the solution comprises an aqueous solution of any one or more of DMF, DMAC, isopropanol or ethanol with a concentration not exceeding 25 wt %.

[0010] The method for preparing the nitrocellulose membrane with backing provided by the present invention may also have the following characteristics: wherein, in step S40, the washing method is a water bath at 20° C. to 50° C. for at least 30 seconds.

[0011] The present invention also provides a nitrocellulose membrane with a backing, which has the following characteristics: it is prepared by any of the aforementioned methods for preparing a nitrocellulose membrane with a backing, wherein the nitrocellulose membrane with a backing comprises: a backing made of PVC material with a thickness of 0.06 mm to 0.10 mm; and a nitrocellulose membrane, which is covered on the backing and is made of nitrocellulose and a hydrophilic polymer.

[0012] The present invention also provides an application of a nitrocellulose membrane with a backing in an in vitro diagnostic reagent having different requirements on the pore size of the NC membrane.

[0013] Functions and Effects of the Invention

[0014] The present invention provides a method for preparing a nitrocellulose membrane with a backing, which can well control the pore size of the membrane during the membrane preparation process by adjusting the dosage of a porogen. The prepared nitrocellulose membrane has the characteristics of uniform pore size and controllable size, and is suitable for in vitro diagnostic reagents with different requirements for the pore size of the NC membrane.

[0015] The present invention provides a method for preparing a nitrocellulose membrane with a backing, by adding a hydrophilic high molecular polymer into the casting solution, which can effectively adjust the hydrophilicity of the NC membrane and solve the foaming problem in the production process on the one hand, and on the other hand, compared with small molecule surfactants, the hydrophilic high molecular polymer is not easy to be lost, thereby ensuring the quality stability of the NC membrane during storage.

[0016] The preparation method of the nitrocellulose membrane with backing of the invention has simple conditions and process and is easy for large-scale production.

[0017] The nitrocellulose membrane with backing provided by the present invention has the characteristics of uniform and controllable pore size, good hydrophilicity, strong protein binding ability and large-scale production, and has broad application prospects in the field of in vitro diagnostic reagents. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a flowchart of a method for preparing a nitrocellulose membrane with a backing according to an embodiment of the present invention;

[0019] Figure 2 1 is a comparison of the capillary migration speeds of samples 1, 11, 12 and 13 of the test examples of the present invention. DETAILED DESCRIPTION

[0020] In order to make the technical means, creative features, objectives and effects of the present invention easy to understand, the following examples and drawings specifically describe a nitrocellulose membrane with a backing and its preparation method and application.

[0021] <Example>

[0022] Figure 1 The present invention is a flowchart of a method for preparing a nitrocellulose membrane with a backing according to an embodiment of the present invention.

[0023] like Figure 1 As shown, this embodiment provides a method for preparing a nitrocellulose membrane with a backing, comprising the following steps:

[0024] S10, dissolving nitrocellulose, a porogen and a hydrophilic polymer in DMF and / or DMAC in the ratio of (10-50) wt %: (1-30) wt %: (1-15) wt %, filtering and standing for more than 4 hours for degassing to obtain a uniform and stable nitrocellulose casting solution,

[0025] Wherein, the porogen includes polyvinyl pyrrolidone and / or polyethylene glycol, and the hydrophilic polymer includes any one or more of sulfonated polyether sulfone, polyaniline or polyacrylamide;

[0026] S20, using a scraper with a scraping thickness of 0.38 mm to scrape the nitrocellulose casting solution onto a PVC backing with a thickness of 0.06 mm to 0.10 mm to form a precursor film;

[0027] S30, separating the precursor film into an aqueous solution of any one or more of DMF, DMAC, isopropanol or ethanol with a concentration not exceeding 25 wt % to obtain a semi-wet film;

[0028] S40, the semi-wet membrane was washed in a 20°C water bath for 30 seconds and then dried to obtain a nitrocellulose membrane with backing

[0029] This embodiment also provides a nitrocellulose membrane with a backing, which is prepared by the preparation method of the nitrocellulose membrane with a backing in this embodiment.

[0030] The nitrocellulose membrane with backing provided in this embodiment comprises: a backing made of PVC material with a thickness of 0.06 mm to 0.10 mm; and a nitrocellulose membrane, which is covered on the backing and is made of nitrocellulose and a hydrophilic polymer.

[0031] Specifically, the specific parameters of the preparation process of the backing nitrocellulose membrane in this embodiment are selected as follows: in step S10, the mass of nitrocellulose is 200g, the porogen is 300g of polyethylene glycol-400, and the hydrophilic polymer is 10g of sulfonated polyethersulfone (sulfonation degree ≥30%), and the above three are dissolved in 490g of DMAC, and the dissolution method is mechanical stirring dissolution at room temperature; in step S20, the scraping film thickness of the scraper is 0.38mm; in step S30, the solution used for phase separation is a 25wt% ethanol aqueous solution, and the immersion time is 3min.

[0032] <Test example>

[0033] In this test example, 15 kinds of films were prepared using the method for preparing a nitrocellulose membrane with a backing provided in the embodiment, which were respectively recorded as samples 1 to 15. The specific parameter selection of the preparation process of samples 1 to 15 is shown in Table 1.

[0034] Table 1 (Specific parameter selection during the preparation of samples 1 to 15)

[0035]

[0036] This test example also refers to the prior art "Example 1 in Chinese Patent CN114130373A" and "Example 2 in Chinese Patent CN114130373A" to prepare two films, which are respectively recorded as Sample 16 and Sample 17.

[0037] This test example performs the following performance characterization tests on samples 1 to 17:

[0038] (1) Use a stopwatch to record the time (in seconds) it takes for purified water to "climb" from the bottom of the membrane to the 4 cm top through capillary action to test the capillary migration rate of the membrane.

[0039] (2) The capillary migration effect of the membrane was evaluated by observing the rising state of the liquid surface during the capillary migration experiment.

[0040] (3) The pore size of the membrane was tested according to the standard GB / T 38949-2020 “Standard particle method for determination of pore size of porous membranes”.

[0041] (4) The protein retention rate of the membrane was determined using bovine serum albumin (BSA). BSA with a molecular weight of 67,000 g / mol was dissolved in a NaCl solution (0.2 mol / L) to prepare a BSA solution. The solution was poured into an ultrafiltration cup and filtered through a nitrocellulose membrane at 0.2 MPa. The retention rate of the membrane for BSA was calculated based on the bovine serum albumin standard curve using the retention rate.

[0042] The results of the above performance characterization tests are shown in Table 2.

[0043] Table 2 (Performance characterization test results of samples 1 to 17)

[0044]

[0045]

[0046] It can be seen from samples 1, 8, 9 and 10 in Table 1 and Table 2 that the pore size of the nitrocellulose membrane with backing in this test example can be controlled by adjusting the amount of the porogen.

[0047] Figure 2 TABLE 1 Capillary migration velocity comparison of samples 1, 11, 12 and 13 of the test example of the present invention. Figure 2 As shown, the "migration speed" value of the backed nitrocellulose membrane in this test example decreases with the increase in the amount of hydrophilic polymer used (the "migration speed" value is the time taken for purified water to "climb" from the bottom of the membrane to the 4 cm top through capillary action. The lower the value, the faster the migration speed and the better the hydrophilicity of the membrane). That is, the hydrophilicity of the membrane can be controlled by adjusting the amount of hydrophilic polymer used.

[0048] As shown in Tables 1 and 2, compared with Sample 1, Sample 14 is a dense membrane with a pore size much smaller than 1 μm, while Sample 15 has poor hydrophilicity and a greater migration speed, which indicates that the pore size and hydrophilicity of the backed nitrocellulose membrane of the present invention are regulated by the porogen and the hydrophilic polymer.

[0049] It can be seen from samples 1, 16 and 17 in Table 1 and Table 2 that the backed nitrocellulose membrane in this test example has better hydrophilicity. This is because the hydrophilic agent polymer used in this test example has better hydrophilicity than general surfactants and polysulfone additives.

[0050] Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a nitrocellulose membrane with a backing, characterized in that: The following steps are involved: S10, dissolving nitrocellulose, a porogen and a hydrophilic polymer in DMF and / or DMAC in the ratio of (10-50) wt %: (1-30) wt %: (1-15) wt % and filtering and degassing to obtain a uniform and stable nitrocellulose casting solution, Wherein, the porogen includes polyvinyl pyrrolidone and / or polyethylene glycol, and the hydrophilic polymer includes any one or more of sulfonated polyether sulfone, polyaniline or polyacrylamide; S20, scraping the nitrocellulose casting solution onto a PVC backing with a thickness of 0.06 mm to 0.10 mm to form a precursor film; S30, separating the precursor film in the solution to obtain a semi-wet film; S40, washing and drying the semi-wet membrane to obtain a nitrocellulose membrane with a backing, The nitrocellulose membrane with backing is a microporous membrane, and the micropore size of the nitrocellulose membrane with backing can be controlled by adjusting the amount of the porogen, and the hydrophilic property of the nitrocellulose membrane with backing can be controlled by adjusting the amount of the hydrophilic polymer.

2. The method for preparing a nitrocellulose membrane with backing according to claim 1, characterized in that: in, In step S10, the degassing treatment method is to stand for more than 4 hours for degassing.

3. The method for preparing a nitrocellulose membrane with backing according to claim 1, characterized in that: in, In step S20, the tool used for film forming is a scraper with a film thickness of 0.38 mm.

4. The method for preparing a nitrocellulose membrane with backing according to claim 1, characterized in that: in, In step S30, the solution includes an aqueous solution of any one or more of DMF, DMAC, isopropanol or ethanol with a concentration not exceeding 25 wt%.

5. The method for preparing a nitrocellulose membrane with backing according to claim 1, characterized in that: in, In step S40, the washing method is a water bath at 20°C to 50°C for at least 30 seconds.

6. A nitrocellulose membrane with backing, characterized in that: Prepared by the method for preparing a nitrocellulose membrane with a backing according to any one of claims 1 to 5, Wherein, the nitrocellulose membrane with backing comprises: PVC backing with a thickness of 0.06mm to 0.10mm; and The nitrocellulose membrane is covered on the backing and is made of nitrocellulose and the hydrophilic polymer.

7. Use of a nitrocellulose membrane with backing as claimed in claim 6 in in vitro diagnostic reagents having different requirements on the pore size of the NC membrane.

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