A molecularly imprinted composite membrane for selectively separating phenylethanoid glycosides and a preparation method and application thereof

Abstract

The application provides a molecular imprinting composite film for selectively separating phenylethanoid glycosides, wherein the matrix of the molecular imprinting composite film is polypropylene, polyethersulfone, polycarbonate, cellulose acetate or polyvinylidene fluoride; and a verbascoside imprinting layer or a trilobatin imprinting layer is synthesized on the surface of the composite film. Compared with the prior art, the application has the following advantages: the composite film provided by the application has a coral-like structure, and has the advantages of easy recycling, no pollution, low energy consumption, excellent separation performance, application in continuous separation process and the like, and effectively solves the problems of few types, low purity, difficult recycling, high energy consumption and secondary pollution; the composite film is a molecular imprinting composite film for efficiently separating phenylethanoid glycosides, which is designed by combining the molecular imprinting technology and the membrane separation method in the technical field of separation of effective components of natural products, and is expected to provide a new application idea and method for high-efficiency separation of phenylethanoid glycosides in effective components of natural products.

Description

Technical Field

[0001] This invention relates to the field of materials separation technology, specifically to a molecularly imprinted composite membrane for selectively separating phenylethanol glycosides, its preparation method, and its application. Technical Background

[0002] Cistanche tubulosa is a perennial parasitic plant belonging to the genus Cistanche in the family Orobanchaceae, often parasitizing the roots of plants in the genus Tamarix. It is edible and possesses nourishing medicinal value. Modern research indicates that it has various effects, including anti-Alzheimer's disease, anti-aging, anti-fatigue, and immune function regulation, as well as kidney-tonifying, essence-boosting, dryness-moistening, and laxative effects. It has broad development and application prospects in medicine, health care, and food. Studies show that the bioactive components in cultivated and wild Cistanche tubulosa are basically the same, mainly consisting of phenylethanoid glycosides, polysaccharides, oligosaccharides, flavonoids, polyphenols, and proteins.

[0003] Currently, the main methods for separating and purifying phenylethanol glycosides include macroporous adsorption resin method, high-speed countercurrent chromatography, membrane separation method, and molecular imprinting technology. Membrane separation method can highly enrich the effective components of natural products, reduce impurities, and efficiently improve product purity. It has the advantages of mild operating conditions, high selectivity, and low energy consumption. However, the membrane materials available for the purification of phenylethanol glycosides are limited in their variety, susceptibility to contamination, and low product purity. Therefore, it is necessary to design novel molecular imprinted composite membranes for the efficient separation of phenylethanol glycosides. Summary of the Invention

[0004] To address the aforementioned technical limitations, this invention proposes a molecularly imprinted composite membrane for selectively separating phenylethanol glycosides, its preparation method, and its application; it overcomes the deficiencies and defects mentioned in the background art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The inventive point of this invention is to provide a molecularly imprinted composite membrane for selectively separating phenylethanoid glycosides. The matrix of the molecularly imprinted composite membrane is polyvinylidene fluoride (PVDF), and a verbascoside (ACT) imprinted layer is synthesized on the surface of the composite membrane. The matrix can also be polyacrylonitrile, polyethersulfone, polycarbonate, cellulose acetate, etc. Alternatively, another active component of phenylethanoid glycosides, echinacoside, can be used as the target molecule to prepare an echinacoside imprinted layer and synthesize it on the surface of the composite membrane.

[0007] Optionally, in the above-mentioned molecularly imprinted composite membrane for selectively separating phenylethanol glycosides, the filler of the composite membrane is amphiphilic multinuclear nanospheres (ANMS).

[0008] The second inventive point of this invention is to provide a method for preparing the above-mentioned molecularly imprinted composite membrane for selectively separating phenylethanol glycosides, comprising the following steps:

[0009] S1. Preparation of emulsifier: After drying, silica (SiO2) nanoparticles were dispersed in toluene, methyltrimethoxysilane and triethylamine were added, and the mixture was ultrasonically dispersed and dissolved. The mixture was then refluxed under nitrogen. The refluxed product was centrifuged, washed with toluene, and dried to obtain methyl-functionalized silica particle emulsifier.

[0010] S2. Preparation of filler: The methyl-functionalized silica particle emulsifier obtained in step S1 is dispersed in toluene to obtain solution A; hexadecyltrimethylammonium chloride (CTAC) and polyazidepropane (PEI) are added to ultrapure water and ultrasonically dispersed to obtain solution B; solutions A and B are mixed evenly to obtain Pickering emulsion, and then tetramethoxysilane (TMOS) and bis(triethoxysilyl)ethane (BTEE) are added, with a total silicon content of 2.8 mmol. The reaction is stirred, the reaction product is centrifuged and washed with toluene, and the obtained product is dried to obtain filler ANMS;

[0011] S3. Preparation of the blend membrane: PVDF powder, polyvinylpyrrolidone (PVP) and the filler ANMS prepared in step S2 are dissolved in N-methylpyrrolidone (NMP), stirred in an oil bath, allowed to stand for degassing, and then scraped into a membrane. The scraped membrane is placed in deionized water for phase inversion reaction to obtain the ANMS@PVDF blend membrane. The blend membrane is stored in deionized water for later use.

[0012] S4. Preparation of composite membrane: ACT, 4-vinylpyridine (4-VP) and acetonitrile were mixed and stirred to prepare a prepolymer complex solution. The ANMS@PVDF blend membrane, ethylene glycol dimethacrylate (EGDMA) and azobisisobutyronitrile (AIBN) prepared in step S3 were added to this solution. After purging with nitrogen, a two-step temperature imprinting polymerization reaction was carried out in a constant temperature oil bath. The product was washed with deionized water and finally ACT was washed away with eluent to obtain the final product, molecularly imprinted composite membrane.

[0013] Optionally, in the above preparation method, in step S1, the drying temperature of SiO2 nanoparticles is 110-130℃, the drying time is 3-5h, the ultrasonic dispersion power is 200-250W, the ultrasonic dispersion time is 0.5-3min, the reflux temperature is 110-130℃, the time is 3-5h, the centrifugation speed of the reflux product is 7500-9000 rpm, the centrifugation time is 4-7min, and the product is washed with toluene 3-5 times.

[0014] Optionally, in the above preparation method, in step S1, the ratio of SiO2 nanoparticles, toluene for dispersion, methyltrimethoxysilane and triethylamine is (1.4g-1.6g):(8-10ml):(0.605-0.624g):(0.450-0.465g).

[0015] Optionally, in the above preparation method, in step S2, the ultrasonic dispersion power of solution B is 200-250 watts, the ultrasonic dispersion time is 0.5-3 minutes, the stirring temperature of the mixture is 35-45℃, the stirring time is 23-25 ​​hours, the centrifugation speed of the reaction product is 7500-9000 rpm, the centrifugation time is 4-7 minutes, the product is washed with toluene 4-6 times, the drying temperature is 35-45℃, and the drying time is 10-13 hours.

[0016] Optionally, in the above preparation method, in step S2, the ratio of methyl-functionalized silica particle emulsifier to toluene for dispersing in solution A is (0.10-0.15g):(30-50ml); in solution B, the ratio of hexadecyltrimethylammonium chloride, polyazidepropane, and ultrapure water is (0.0750-0.0800g):(0.4-0.5g):(1.5000-1.5300g); and the ratio of tetramethoxysilane to bis(triethoxysilyl)ethane is (0.2710-0.2720g):(0.1806-0.1810g).

[0017] Optionally, in the above preparation method, in step S3, the oil bath temperature is 45-55℃, the stirring time is 24-25h, the standing degassing temperature is 45-55℃, and the time is 12-14h; the ratio of PVDF powder, PVP, filler ANMS and NMP is (3.0-4.0g):(0.1-0.2g):(0.1-0.4g):(22-24g).

[0018] Optionally, in the above preparation method, in step S4, the mixing and stirring time is 12-14 h, the nitrogen gas is introduced for 20-40 min, the two-step temperature imprinting polymerization reaction is carried out in an oil bath at 40-50℃ for 16-18 h and in an oil bath at 55-60℃ for 6-8 h, the washing with ethanol and deionized water is at least 3-5 times, the eluent is methanol / acetic acid (9:1, v / v), and the elution time is 2-12 h; the ratio of ACT, 4-VP, acetonitrile, ANMS@PVDF blend membrane prepared in step S3, EGDMA and AIBN is (0.1-0.3 mmol): (4-6 mmol: (80-100 ml): (3-4 pieces): (6-7 mmol): (0.1-0.2 mmol).

[0019] The third inventive point of this invention is to provide the application of the above-mentioned molecularly imprinted composite membrane and the molecularly imprinted composite membrane prepared by the above-mentioned preparation method in the separation of phenylethanol glycosides, wherein the molecularly imprinted composite membrane has a coral-like structure and the phenylethanol glycosides are verbascosides.

[0020] Molecularly imprinted composite membranes with a coral-like structure constructed based on amphiphilic multinuclear nanospheres possess a dendritic and porous surface, optimizing exposed imprinted cavities and sites, and improving the adsorption capacity and selectivity of verbascoside. Furthermore, the amphiphilic multinuclear nanospheres, with their large specific surface area and porous structure, can increase the imprinting area, thereby introducing more imprinting sites and improving the separation and purification of verbascoside from phenylethanol glycosides. Simultaneously, the amino groups of the hydrophilic daughter cores of the amphiphilic multinuclear nanospheres can couple with the molecularly imprinted polymer via hydrogen bonds, providing more imprinting sites for verbascoside. Molecular imprinting technology is a highly efficient molecular recognition technique with advantages such as high selectivity and simple operation, making it one of the more ideal methods for separating the effective components of natural products.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] This invention provides a molecularly imprinted composite membrane for selectively separating phenylethanoid glycosides, its preparation method, and its application. The composite membrane has a coral-like structure and possesses advantages such as easy material recovery, no pollution, low energy consumption, excellent separation performance, and applicability to continuous separation processes. It effectively solves the shortcomings and disadvantages of limited variety, low purity, difficult recovery, high energy consumption, and susceptibility to secondary pollution. This composite membrane is a molecularly imprinted composite membrane designed by combining molecular imprinting technology with membrane separation in the field of natural product active ingredient separation technology. It is expected to provide new application ideas and methods for the efficient separation of phenylethanoid glycosides from natural product active ingredients.

[0023] Prior to this invention, no composite membranes with a coral-like structure had been reported. The molecularly imprinted composite membrane with a coral-like structure has a dendritic and porous surface. The increased area of ​​the imprinted layer on the membrane surface and the increased number of imprinted cavities and sites result in the molecularly imprinted composite membrane having higher adsorption and separation performance for verbascoside.

[0024] This invention utilizes the molecularly imprinted composite membrane to separate phenylethanoid glycosides from *Cistanche tubulosa*. The adsorption capacity of verbascoside reached 110.95 mg / g, and the adsorption capacity of echinacoside reached 21.53 mg / g, with a selectivity of 5.15. In the permeability selectivity experiment, the permeability coefficient of verbascoside was 0.0068 cm⁻¹. 2 ·h -1 The permeability coefficient of echinacoside is 0.0686 cm⁻¹. 2 ·h -1The penetration selection factor is 10.04. Attached Figure Description

[0025] Figure 1 The chemical formula for the synthesis of a molecularly imprinted composite membrane for selectively separating phenylethanol glycosides is shown in one embodiment of the present invention.

[0026] Figure 2 This is a microscopic image (SEM image) of the coral-like structure of a molecularly imprinted composite membrane for the selective separation of phenylethanol glycosides according to an embodiment of the present invention.

[0027] Figure 3 The image shows the microstructure (SEM) of the prior art (i.e., the prior art) mentioned in Comparative Example 3. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below. However, it should be understood that the description herein is merely illustrative and not intended to limit the scope of the invention.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. All reagents and instruments used herein are commercially available, and the characterization methods involved are described in relevant prior art and will not be repeated herein.

[0030] To further understand the present invention, the present invention will be described in detail below with reference to the preferred embodiments.

[0031] Example 1

[0032] A coral-like molecularly imprinted composite membrane for selectively separating phenylethanol glycosides is proposed, which utilizes the specific recognition function of the phenylethanol glycoside molecularly imprinted membrane to separate and purify phenylethanol glycosides from Cistanche tubulosa.

[0033] The method for preparing a coral-like molecularly imprinted composite membrane for separating phenylethanol glycosides includes the following steps:

[0034] Step 1: 1.5 g of SiO2 nanoparticles were dried at 120 °C for 4 h, and then dispersed in 8 mL of toluene. 0.612 g of methyltrimethoxysilane and 0.455 g of triethylamine were weighed and added sequentially to the above solution, and then sonicated to disperse and dissolve. Next, the mixture was refluxed under N2 atmosphere for 4 h (120 °C). After reflux, the resulting product was centrifuged, washed four times with toluene, and dried to obtain methyl-functionalized SiO2 particles.

[0035] Step 2: Weigh 0.12 g of the synthesized methyl-functionalized SiO2 particles (emulsifier) ​​and disperse them in 40 mL of toluene to form solution A. Add 0.075 g of CTAC and 0.4 g of PEI to 1.525 g of ultrapure water and sonicate to disperse and dissolve them to form solution B. Next, mix solution A and solution B thoroughly to form a Pickering emulsion. Then, add TMOS and BTEE (total silicon content 2.8 mmol) and stir at 40 °C for 24 h. After the reaction is complete, centrifuge the product and wash it several times with toluene. Finally, dry at 40 °C for 12 h to obtain ANMS.

[0036] Step 3: Dissolve 3.5g of PVDF powder, 0.1g of PVP and 0.3g of ANMS in 23g of NMP, mechanically stir in an oil bath at 50℃ for 24h, and then let stand at 50℃ for 12h for degassing.

[0037] Step 4: After the above reaction is completed, use a casting knife to remove the casting solution and start scraping the membrane. Place the scraped membrane in deionized water to carry out the phase inversion reaction. Finally, store the obtained ANMS@PVDF blend membrane in deionized water for later use.

[0038] Step 5: 0.25 mmol of ACT, 6 mmol of 4-VP, and 80 mL of acetonitrile were sequentially added to a round-bottom flask, and the mixture was stirred overnight for 12 h to prepare a prepolymerized complex. Then, ANMS@PVDF blend membrane, 6 mmol of EGDMA, and 0.1 mmol of AIBN were added to the above mixture, and nitrogen gas was purged for 30 min to remove oxygen. After nitrogen purging, the flask was placed in a constant-temperature oil bath and reacted at 50 °C for 18 h, followed by a two-step temperature-imprinted polymerization reaction at 55 °C for 6 h. After the reaction, the product was washed with deionized water at least three times.

[0039] Step 6: Wash away the ACT from the membrane obtained in Step 5 with an eluent to obtain the molecularly imprinted composite membrane.

[0040] In Step 6, the eluent is methanol and acetic acid, with a mixing ratio of 9:1 (v / v), and the elution time is 10 hours.

[0041] In Step 5, phenylethanol glycosides serve as template molecules, including but not limited to ACT.

[0042] Example 2

[0043] Preparation of ACT-type molecularly imprinted membranes: An ANMS@PVDF blend membrane was prepared by dissolving 3.5 g of PVDF powder and 0.1 g of PVP in 23 g of NMP with 0.1 g of ANMS. 0.2 mmol of ACT, 6 mmol of 4-VP, and 80 mL of acetonitrile were added sequentially to a round-bottom flask, and the mixture was stirred overnight for 12 h to prepare a prepolymerized complex. Then, the ANMS@PVDF blend membrane, 6 mmol of EGDMA, and 0.1 mmol of AIBN were added to the above mixture, and nitrogen gas was purged for 30 min to remove oxygen. After nitrogen purging, the flask was placed in a constant-temperature oil bath and reacted at 50 °C for 18 h, followed by a two-step temperature-imprinted polymerization reaction at 55 °C for 6 h. After the reaction, the product was washed with deionized water at least three times and then placed in a container. That is, an ACT-type molecularly imprinted membrane was obtained, and the ACT was washed off the membrane with an elution buffer for 12 hours.

[0044] Adsorption experiment of ACT-based molecularly imprinted membrane on 0.5 mg / mL crude ACT extract (≥50%): The eluted imprinted membrane was placed in a 50 mL Erlenmeyer flask, and 20 mL of 0.5 mg / mL crude ACT extract was added. The flask was sealed and placed on a shaker at 150 rpm for 24 h at 30 °C. The ACT content after adsorption was determined by HPLC. The adsorption capacity of ACT was 55.87 mg / g.

[0045] Example 3

[0046] The preparation method is the same as in Example 1, except that the amount of ANMS added is 0.2g.

[0047] The prepared molecularly imprinted membrane was used to separate phenylethanol glycosides, and its adsorption capacity for ACT was 86.60 mg / g.

[0048] Example 4

[0049] The preparation method is the same as in Example 1, except that the amount of ANMS added is 0.3g.

[0050] The prepared molecularly imprinted membrane was used to separate phenylethanol glycosides, and its adsorption capacity for ACT was 105.95 mg / g.

[0051] Example 5

[0052] The preparation method is the same as in Example 1, except that the amount of ANMS added is 0.4g.

[0053] The prepared molecularly imprinted membrane was used to separate phenylethanol glycosides, and its adsorption capacity for ACT was 89.45 mg / g.

[0054] Example 6

[0055] The preparation method is the same as in Example 1, except that the amount of ANMS added is 0.3g and the amount of ACT added is 0.1mmol.

[0056] The prepared molecularly imprinted membrane was used to separate phenylethanol glycosides, and its adsorption capacity for ACT was 61.59 mg / g.

[0057] Example 7

[0058] The preparation method is the same as in Example 1, except that the amount of ANMS added is 0.3g and the amount of ACT added is 0.15mmol.

[0059] The prepared molecularly imprinted membrane was used to separate phenylethanol glycosides, and its adsorption capacity for ACT was 74.45 mg / g.

[0060] Example 8

[0061] The preparation method is the same as in Example 1, except that the amount of ANMS added is 0.3g and the amount of ACT added is 0.20mmol.

[0062] The prepared molecularly imprinted membrane was used to separate phenylethanol glycosides, and its adsorption capacity for ACT was 95.28 mg / g.

[0063] Example 9

[0064] The preparation method is the same as in Example 1, except that the amount of ANMS added is 0.3g and the amount of ACT added is 0.25mmol.

[0065] The prepared molecularly imprinted membrane was used to separate phenylethanol glycosides, and its adsorption capacity for ACT was 102.36 mg / g.

[0066] Example 10

[0067] The preparation method is the same as in Example 1, except that the amount of ANMS added is 0.3g and the amount of ACT added is 0.3mmol.

[0068] The prepared molecularly imprinted membrane was used to separate phenylethanol glycosides, and its adsorption capacity for ACT was 96.12 mg / g.

[0069] Example 11

[0070] The preparation method is the same as in Example 1, except that: the amount of ANMS added is 0.3g, the amount of ACT added is 0.25mmol, and the elution time of ACT is 2h.

[0071] The prepared molecularly imprinted membrane was used to separate phenylethanol glycosides, and its adsorption capacity for ACT was 32.19 mg / g.

[0072] Example 12

[0073] The preparation method is the same as in Example 1, except that: the amount of ANMS added is 0.3g, the amount of ACT added is 0.25mmol, and the elution time of ACT is 4h.

[0074] The prepared molecularly imprinted membrane was used to separate phenylethanol glycosides, and its adsorption capacity for ACT was 47.76 mg / g.

[0075] Example 13

[0076] The preparation method is the same as in Example 1, except that: the amount of ANMS added is 0.3g, the amount of ACT added is 0.25mmol, and the elution time of ACT is 6h.

[0077] The prepared molecularly imprinted membrane was used to separate phenylethanol glycosides, and its adsorption capacity for ACT was 74.60 mg / g.

[0078] Example 14

[0079] The preparation method is the same as in Example 1, except that: the amount of ANMS added is 0.3g, the amount of ACT added is 0.25mmol, and the elution time of ACT is 8h.

[0080] The prepared molecularly imprinted membrane was used to separate phenylethanol glycosides, and its adsorption capacity for ACT was 95.28 mg / g.

[0081] Example 15

[0082] The preparation method is the same as in Example 1, except that: the amount of ANMS added is 0.3g, the amount of ACT added is 0.25mmol, and the elution time of ACT is 10h.

[0083] The prepared molecularly imprinted membrane was used to separate phenylethanol glycosides, and its adsorption capacity for ACT was 105.32 mg / g.

[0084] Example 16

[0085] The preparation method is the same as in Example 1, except that: the amount of ANMS added is 0.3g, the amount of ACT added is 0.25mmol, and the elution time of ACT is 12h.

[0086] The prepared molecularly imprinted membrane was used to separate phenylethanol glycosides, and its adsorption capacity for ACT was 98.26 mg / g.

[0087] Example 17

[0088] The preparation method for ACT-type molecularly imprinted membranes was the same as in Example 1, except that the amount of ANMS added was 0.3 g, the amount of ACT added was 0.25 mmol, and the elution time for ACT was 10 h.

[0089] Selective adsorption experiment of ACT-based molecularly imprinted composite membrane for 0.6 mg / mL phenylethanoid glycoside standard: The eluted molecularly imprinted composite membrane was placed in a 50 mL Erlenmeyer flask, and 20 mL of 0.6 mg / mL phenylethanoid glycoside standard was added. The flask was sealed and placed on a shaker at 150 rpm for 24 h at 30 °C. The content of ACT after adsorption was determined by HPLC. The adsorption capacity of ACT reached 110.95 mg / g, and the adsorption capacity of echinacoside reached 21.53 mg / g, with a selectivity of 5.15.

[0090] Example 18

[0091] The ACT-type molecularly imprinted membrane was prepared in the same manner as the molecularly imprinted membrane prepared in Example 14.

[0092] Permeability selectivity experiment of ACT-type molecularly imprinted membrane for phenylethanoid glycoside standard: The molecularly imprinted membrane (effective membrane area measured) was fixed in an H-type permeation apparatus. 50 mL of 0.6 mg / mL phenylethanoid glycoside standard was added to one side of the feed cell, and the same volume of ultrapure water was added to the other side of the receiving cell. Magnetic stirrers were placed on both sides for sealing and stirring. The concentrations of ACT and echinacoside on both sides were determined by HPLC at regular intervals. The experiment lasted for 24 hours. The permeability coefficient of ACT was 0.0068 cm⁻¹. 2 ·h -1 The permeability coefficient of echinacoside is 0.0686 cm⁻¹. 2 ·h -1 The penetration selection factor is 10.04.

[0093] Comparative Example 1:

[0094] Preparation of ACT-type non-molecularly imprinted membranes: An ANMS@PVDF blend membrane was prepared by dissolving 3.5 g of PVDF powder and 0.1 g of PVP in 23 g of NMP with 0.3 g of ANMS. 6 mmol of 4-VP and 80 mL of acetonitrile were added sequentially to a round-bottom flask, and the mixture was stirred overnight for 12 h to prepare a prepolymerized complex. Then, the ANMS@PVDF blend membrane, 6 mmol of EGDMA, and 0.1 mmol of AIBN were added to the above mixed solution, and nitrogen gas was purged for 30 min to remove oxygen. After nitrogen purging, the flask was placed in a constant-temperature oil bath and reacted at 50 °C for 18 h, followed by a two-step temperature-imprinted polymerization reaction at 55 °C for 6 h. After the reaction, the product was washed with deionized water at least three times to obtain the ACT-type non-molecularly imprinted membrane.

[0095] Selective adsorption experiment of 0.6 mg / mL phenylethanoid glycoside standard on non-molecularly imprinted membrane: The non-molecularly imprinted membrane was placed in a 50 mL Erlenmeyer flask, 20 mL of 0.6 mg / mL phenylethanoid glycoside standard was added, and the flask was sealed and placed on a shaker at 150 rpm for 24 h at 30 °C. The content of purified ACT was determined by HPLC. The adsorption capacity of ACT after adsorption reached 29.32 mg / g, and the adsorption capacity of echinacoside reached 25.27 mg / g, with a selectivity of 1.16.

[0096] Comparative Example 2:

[0097] The ACT non-molecularly imprinted membrane was prepared in the same manner as the non-molecularly imprinted membrane prepared in Comparative Example 1.

[0098] Permeability selectivity experiment of non-molecularly imprinted membrane for phenylethanoid glycoside standard: A non-molecularly imprinted membrane (with measured effective membrane area) was fixed in an H-type permeation apparatus. 50 mL of 0.6 mg / mL phenylethanoid glycoside standard was added to one side of the feed cell, and the same volume of ultrapure water was added to the other side of the receiving cell. Both sides were sealed and stirred with magnetic stirrers. The ACT content on both sides was determined by HPLC at regular intervals. The experiment lasted for 24 hours. The ACT permeability coefficient was 0.2940 cm⁻¹. 2 ·h -1 The permeability coefficient of echinacoside is 1.0660 cm⁻¹. 2 ·h -1 The penetration selectivity factor is 3.63.

[0099] Comparing the membrane performance of the molecularly imprinted composite membrane prepared by the technical solution of this invention with that of the non-molecularly imprinted ACT membranes (Comparative Examples 1 and 2), it was found that the molecularly imprinted composite membrane prepared by the technical solution of this invention increased the adsorption capacity of verbascoside by 3.78 times, the selectivity by 4.44 times, while the permeation coefficient decreased by 43 times and the selective permeation factor increased by 2.77 times. This indicates that the molecularly imprinted composite membrane prepared by the technical solution of this invention has a significant advantage in the selective separation of verbascoside.

[0100] Comparative Example 3:

[0101] The patent CN 112619435 A, entitled "A Method for Preparing a Molecularly Imprinted Hybrid Membrane for Separating Phenylephrines," describes a method for preparing a molecularly imprinted hybrid membrane for separating phenylephrines by constructing an imprinted network structure within the membrane. The method involves adding 1.8 g of PEI, 0.1 g of PEI@MCM-41, 0.2 mmol of ACT molecules, 6 mmol of 4-VP as a functional monomer, 6 mmol of EGDMA as a crosslinking agent, and 0.1 mmol of AIBN as an initiator, and then performing in-situ polymerization to prepare the composite filler MIP-PEI / MCM-41. Finally, 400 mg of MIP-PEI / MCM-41, 4 g of polyvinylidene fluoride powder, 0.1 g of PVP, and 23 g of NMP are added to prepare the molecularly imprinted hybrid membrane through phase inversion.

[0102] Under the same test conditions, this molecularly imprinted hybrid membrane was applied to the separation of phenylethanoid glycosides. The adsorption capacity of ACT reached 96.24 mg / g, and the adsorption capacity of echinacoside reached 22.37 mg / g, with a selectivity of 4.440. In the permeability selectivity experiment, the permeability coefficient of verbascoside was 0.005 cm⁻¹. 2 ·h -1 The permeability coefficient of echinacoside is 0.032 cm⁻¹. 2 ·h -1 The penetration selection factor is 6.370.

[0103] The patented technology was compared with the technical solution of this invention, and the specific comparison results are shown in Table 1.

[0104] Table 1

[0105]

[0106]

[0107] As shown in Table 1, compared with the prior art, the membrane of this invention improves the adsorption capacity, selectivity, and permeation selectivity of verbascoside. The prior art uses a filler with imprinted sites mixed into the membrane to prepare a molecularly imprinted hybrid membrane. In contrast, the molecularly imprinted composite membrane of this invention constructs an imprinted layer with imprinted sites on the surface of the blended membrane, effectively reducing the probability of imprinted sites being embedded and improving the adsorption and separation performance of verbascoside by the molecularly imprinted composite membrane. Performance results show that the molecularly imprinted composite membrane of this invention increases the adsorption capacity of verbascoside by 14.71 mg / g, the selectivity by 1.16 times, and the permeation selectivity by 1.58 times compared to the molecularly imprinted hybrid membrane of the prior art.

[0108] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a molecularly imprinted composite membrane for selectively separating phenylethanoid glycosides, characterized by, The method comprises the following steps: Preparation of the emulsifier: after drying the silica nanoparticles, disperse them in toluene, add methyltrimethoxysilane and triethylamine, ultrasonic dispersion and dissolution, reflux under nitrogen environment, centrifuge the reflux product, wash with toluene, and dry to obtain the methyl-functionalized silica particle emulsifier; Preparation of the filler: disperse the methyl-functionalized silica particle emulsifier prepared in step S1 in toluene to obtain solution A; ultrasonic dispersion of cetyltrimethylammonium chloride and polyaziridine in ultrapure water to obtain solution B; mix solution A and solution B to obtain a Pickering emulsion, and then add tetramethoxysilane and bis(triethoxysilyl)ethane, stir and react, centrifuge the reaction product, wash with toluene, and dry the obtained product to obtain the filler, the amphiphilic multi-nuclear nanosphere; Preparation of the blended membrane: dissolve polyvinylidene fluoride powder, polyvinylpyrrolidone and the filler prepared in step S2 in N-methylpyrrolidone, stir in an oil bath, stand and degas, scrape the membrane after degassing, and place the scraped membrane in deionized water for phase inversion reaction to obtain the ANMS@PVDF blended membrane, which is stored in deionized water for use; Preparation of the composite membrane: mix verbascoside, 4-vinylpyridine and acetonitrile to prepare a prepolymerization complex solution, add the ANMS@PVDF blended membrane prepared in step S3, ethylene glycol dimethacrylate and azobisisobutyronitrile to the solution, introduce nitrogen, and perform two-step temperature imprinting polymerization under constant temperature oil bath to obtain the product, which is washed with deionized water, and finally washed with the eluent to remove verbascoside, thereby obtaining the final product, the molecularly imprinted composite membrane.

2. The production method according to claim 1, characterized by, In step S1, the drying temperature of the silica nanoparticles is 110-130°C, the drying time is 3-5h, the ultrasonic dispersion power is 200-250w, the ultrasonic dispersion time is 0.5-3min, the reflux temperature is 110-130°C, the reflux time is 3-5h, the centrifugation speed of the reflux product is 7500-9000r / min, and the centrifugation time is 4-7min, and the toluene washing is performed 3-5 times.

3. The production method according to claim 2, characterized by, In step S1, the amount of silica nanoparticles, toluene for dispersion, methyltrimethoxysilane and triethylamine is 1.4g-1.6g:8-10ml:0.605-0.624g:0.450-0.465g.

4. The method of claim 1, wherein, In step S2, the ultrasonic dispersion power of solution B is 200-250w, the ultrasonic dispersion time is 0.5-3min, the stirring temperature of the mixed solution is 35-45°C, the stirring time is 23-25h, the centrifugation speed of the reaction product is 7500-9000r / min, the centrifugation time is 4-7min, the toluene washing is performed 4-6 times, the drying temperature is 35-45°C, and the drying time is 10-13h.

5. The preparation method according to claim 4, characterized in that, The amount ratio of methyl functionalized silica particle emulsifier and toluene for dispersion in solution A of step S2 is 0.10-0.15 g:30-50 ml; the amount ratio of cetyltrimethylammonium chloride, polyaziridine and ultrapure water in solution B is 0.0750-0.0800 g:0.4-0.5 g:1.5000-1.5300 g; the amount ratio of tetramethoxysilane and bis(triethoxysilyl)ethane is 0.2710-0.2720 g:0.1806-0.1810 g.

6. The method of claim 1, wherein, In step S3, the oil bath temperature is 45-55℃, the stirring time is 24-25 h, the standing degassing temperature is 45-55℃, and the time is 12-14 h; the amount ratio of polyvinylidene fluoride powder, polyvinylpyrrolidone, filler amphiphilic multi-nuclear nanospheres and N-methylpyrrolidone is 3.0-4.0 g:0.1-0.2 g:0.1-0.4 g:22-24 g.

7. The preparation method according to claim 1, characterized in that, In step S4, the mixing and stirring time is 12-14 h, the nitrogen gas is introduced for 20-40 min, the two-step temperature imprinting polymerization reaction is 45-50℃ oil bath reaction for 16-18 h and 55-60℃ oil bath reaction for 6-8 h, respectively, the product is washed with ethanol and deionized water for at least 3-5 times, the eluent is methanol / acetic acid with a volume ratio of 9:1, and the elution time is 2-12 h; the amount ratio of verbascoside, 4-vinylpyridine, acetonitrile, ANMS@PVDF blended membrane prepared in step S3, ethylene glycol dimethacrylate and azobisisobutyronitrile is 0.1-0.3 mmol:4-6 mmol:80-100 ml:3-4 pieces:6-7 mmol:0.1-0.2 mmol.

8. The molecularly imprinted composite membrane for selectively separating phenylethanoid glycosides prepared by the preparation method of any one of claims 1 to 7, characterized in that, The matrix of the molecular imprinting composite film is polypropylene, polyether sulfone, polycarbonate, cellulose acetate or polyvinylidene fluoride; the composite film surface is synthesized with a verbascoside imprinting layer or a trichosanthin imprinting layer; the filler of the composite film is amphiphilic multi-nuclear nanospheres. 9.The molecularly imprinted composite film for selectively separating phenylethanoid glycosides according to claim 8, wherein, The matrix of the molecular imprinting composite film is polyvinylidene fluoride.

10. The molecularly imprinted composite film for selectively separating phenylethanoid glycosides according to claim 9, wherein the phenylethanoid glycoside is acteoside. The composite film surface is synthesized with a verbascoside imprinting layer.

11. The molecularly imprinted composite film prepared by the method according to any one of claims 1-7, or the use of the molecularly imprinted composite film according to any one of claims 8-10 in separating phenylethanoid glycosides, characterized in that, The molecular imprinting composite film is a coral-like structure, and the phenylethanoid glycoside is verbascoside.

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