Antibacterial, anti-pollution and high-flux polyethersulfone membrane for polypeptide separation and purification

Abstract

The invention relates to an antibacterial, anti-pollution and high-flux polyethersulfone membrane for polypeptide separation and purification, which is prepared by the following steps: dissolving a base material in a solvent, adding a pore-forming agent and a synthesized modifier, and heating and stirring until a yellow transparent membrane casting solution is formed; the modifier is mainly synthesized and prepared from amino acid hydrochloride. The D-A modifier is blended with the base material, the solvent and the pore-forming agent, so that the blending modification effect is achieved. In the experiment, the antibacterial anti-pollution high-flux polyethersulfone membrane for polypeptide separation and purification is prepared by adopting a phase inversion process. The method has the advantages that the synthesis conditions of the modifier are mild, and the method is simple; due to the addition of the modifier, hydrophilic modification of the surface of the membrane is realized, the antibacterial and anti-pollution performance and flux of the membrane are also obviously improved, long-term stable operation of the membrane is facilitated, and the membrane has relatively good transmittance to polypeptide and a very good rejection rate to macromolecular impurities; the prepared antibacterial, anti-pollution and high-flux polyether sulfone membrane separated and purified by the polypeptide has wide application.

Description

Technical Field

[0001] The present invention relates to an antibacterial and anti-fouling high-flux polyethersulfone membrane for polypeptide separation and purification, belonging to the technical field of separation membrane preparation. The modified membrane has the advantages of high pure water flux, good polypeptide permeability, good anti-fouling and antibacterial effects, and is suitable for polypeptide separation and other fields. Background Art

[0002] With the development of bioengineering technology, a large number of bioengineering products continue to emerge. In recent years, based on genetic engineering technology research, a new class of peptides and protein series substances have been developed and manufactured. Peptides have strong activity and can be widely used in many medical fields such as drugs, vaccines, and clinical research. However, the separation and purification technology in the preparation process of peptides has always been one of the main reasons for its high cost. Traditional peptide separation technologies include salting out, gel filtration, isoelectric precipitation, affinity chromatography, etc. These traditional methods have the disadvantages of high water consumption and high energy consumption. Applying membrane separation technology to the separation and purification of peptides can greatly reduce energy consumption and improve economic benefits.

[0003] Polyethersulfone is a thermoplastic polymer material with excellent comprehensive performance. Through the phase separation method, polyethersulfone can be made into a semipermeable membrane material with a porous structure. The polyethersulfone membrane exhibits excellent antioxidant properties, thermal stability, anti-hydrolysis and good mechanical properties. The membrane structure of the polyethersulfone membrane prepared by phase separation will be affected by multiple factors during the preparation process, including the concentration of the polyethersulfone casting solution, the type of solvent, the type of modifier added, the operating temperature and the type of coagulation bath. Polyethersulfone membranes are used in clinical hemodialysis, plasma separation, industrial wastewater treatment, oil-water separation, ultrafiltration clarification of sugarcane molasses, refined edible oil and other fields. However, due to its hydrophobicity, polyethersulfone membranes are prone to adsorb impurities such as non-polar solutes, colloidal particles and microorganisms when used for a long time in the water environment system, resulting in reduced membrane flux, unstable separation performance, and shortened service life of the polyethersulfone membrane.

[0004] Polyethersulfone membranes with anti-fouling, antibacterial and high-throughput properties can be widely used in actual production. At present, the anti-fouling and protein retention effects of polyethersulfone membranes in the separation process have been studied at home and abroad, but there are few studies on the application of polyethersulfone membranes in biomanufacturing products such as peptides. Therefore, it is necessary to prepare an antibacterial, anti-fouling, high-throughput hydrophilic modified polyethersulfone membrane with good protein retention performance, while meeting the requirements of peptide separation and purification. Summary of the invention

[0005] The purpose of the present invention is to address the problem that the current membrane is easily contaminated and cannot meet the requirements of membrane separation well, and to prepare an antibacterial and anti-fouling high-flux polyethersulfone membrane for polypeptide separation and purification. The method for preparing the hydrophilic modified polyethersulfone membrane has the advantages of high flux, good anti-fouling performance, good polypeptide permeation effect, etc. It is suitable for membrane separation process and can ensure excellent separation effect and long-term stable operation.

[0006] The antibacterial and anti-fouling high-flux polyethersulfone membrane for polypeptide separation and purification prepared by the present invention is first modified by a blending modification method, and then the casting liquid is prepared by a phase separation method, comprising the following steps: Step 1): The substances involved in the synthesis step of the DA modifier are composed of the following mass percentages: polyvinyl alcohol 0.5-2%, dimethyl sulfoxide 12.5-20%, amino acid hydrochloride 2-3%, and acetone 75-85%. Mix and dissolve polyvinyl alcohol and dimethyl sulfoxide at 55-65 °C and adjust the pH to 3-4 with aqueous sulfuric acid solution. Add the weighed amino acid hydrochloride to the above solution and ultrasonicate for 5-10 min until completely dissolved; with the help of light-induced technology, irradiate with an ultraviolet lamp with a wavelength of 365 nm for 15-30 min; stir in an oil bath at 120-130 °C for 16-24 h; add acetone solution to the filtrate obtained by vacuum filtration; filter again and perform Soxhlet extraction on the filter residue. Soak the filter residue in acetone extract and siphon at 80-84 °C until the acetone extract is clear to obtain a DA modifier; vacuum dry and grind into powder; Step 2): The casting solution is prepared by the following components in mass percentage: 15-20% polyethersulfone, 40-60% pore-forming agent, 0.25-1% DA modified material, and the remainder is solvent. The substrate is a hydrophobic polymer, which is dissolved in a solvent and then the pore-forming agent is added and heated and stirred. After dissolution, the DA modified material prepared in (1) is dissolved in the solvent and added, and stirring is continued until a transparent casting solution is formed, and it is allowed to stand for degassing and standby; Step 3) Preparation of modified membrane: Spread the casting solution in step (2) into a thin layer using a scraper and immerse it in a phase inversion solution for phase inversion. The thickness of the thin layer formed by spreading the casting solution is 150-250 µm. Wash the solidified membrane with pure water until there is no obvious foam in the washing solution to obtain an antibacterial and anti-fouling high-flux hydrophilic modified polyethersulfone membrane, which is then immersed in a phase inversion solution for storage.

[0007] Preferably, the stirring time of D-arginine hydrochloride in step 1) is 16-24 h.

[0008] Preferably, the amino acid hydrochloride material in step 1) is one or more of D-arginine hydrochloride, L-arginine hydrochloride, and lysine hydrochloride.

[0009] Preferably, the solvent in step 2) can be one of N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone.

[0010] Preferably, the pore-forming agent in step 2) can be one of polyethylene glycol (MW=400-8000), hydroxypropyl cellulose and polyvinyl pyrrolidone.

[0011] Preferably, the mass percentage of the DA modifier in step 2) is 0.25-1%.

[0012] Preferably, the phase conversion liquid in step 3) is one of ethanol aqueous solutions with an ethanol volume fraction of 0%, 20%, 40%, 60%, 80%, and 100%.

[0013] The invention discloses an antibacterial and anti-fouling high-flux polyethersulfone membrane for separating and purifying polypeptides, characterized in that the pure water flux of the composite membrane is 600-800 L·m -2 ·h -1 , bovine serum albumin retention rate ≥ 99%, polypeptide permeability ≥ 99%, and has obvious antibacterial effect. Beneficial Effects

[0014] Compared with the prior art, the present invention modifies the membrane by a blending method, dissolves the modified monomer in the casting solution, greatly improves its stability, and then prepares a modified polyethersulfone membrane with high flux, good antifouling and antibacterial properties, good polypeptide permeability, and good long-term stability by a non-solvent-induced phase transformation method. The introduction of ammonium ions into the substrate enhances its hydrophilicity and improves its antifouling performance, thereby ensuring the stability of the membrane in long-term operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Scanning electron microscope image of the dense surface of the polyethersulfone modified membrane of Example 1 of the present invention Figure 2 Scanning electron microscope image of the dense surface of the polyethersulfone modified membrane of the present invention Figure 3 SEM image of the cross section of the polyethersulfone modified membrane of Example 5 of the present invention Figure 4 The casting solution of the polyethersulfone modified membrane of the embodiment of the present invention Implementation

[0016] The present invention is further described below in conjunction with specific embodiments. Example

[0017] Step 1): Preparation of DA modifier: The substances involved in the synthesis step of DA modifier are composed of the following substances, 2.2 g of polyvinyl alcohol, 50 ml of dimethyl sulfoxide, 9.1 g of D-arginine hydrochloride, and 300 ml of acetone. Mix and dissolve polyvinyl alcohol and dimethyl sulfoxide at 65 °C and adjust the pH to 3.5 with aqueous sulfuric acid solution. Add the weighed amino acid hydrochloride to the above solution and ultrasonicate for 10 min until completely dissolved; with the help of light-induced technology, irradiate with an ultraviolet lamp with a wavelength of 365 nm for 20 min; stir in an oil bath at 120 °C for 24 h; add acetone solution to the filtrate obtained by vacuum filtration; filter again and perform Soxhlet extraction on the filter residue. Soak the filter residue in acetone extract and siphon at 80 °C until the acetone extract is clear to obtain the DA modifier; vacuum dry and grind into powder; Step 2): The casting solution is prepared from the following components: 17 g of polyethersulfone as the substrate, 43 g of polyethylene glycol (MW=400) as the pore-forming agent, 0.25 g of DA modified material, and the remaining amount of solvent N,N-dimethylacetamide. Dissolve it in the solvent and then add the pore-forming agent and heat and stir. After dissolving, dissolve the DA modified material prepared in (1) in the solvent and add it, continue stirring until a transparent casting solution is formed, and let it stand for degassing and standby; Step 3) Preparation of modified membrane: Use a scraper with a speed of 30 mm / s to spread the casting liquid in step (2) into a thin layer and then immerse it in a phase transformation liquid for phase transformation. The phase transformation liquid is pure water. The thickness of the thin layer formed by spreading the casting liquid is 250µm. The solidified membrane is washed with pure water until there is no obvious foam in the washing liquid to obtain an antibacterial and anti-fouling high-flux hydrophilic modified polyethersulfone membrane, which is then immersed in a phase transformation liquid for storage.

[0018] The pure water flux of the composite membrane is 600 L·m -2 ·h -1 , BSA retention rate ≥99.1%, polypeptide permeability ≥99.3%. The membrane was placed on the surface of a culture medium containing Gram-negative Escherichia coli and Staphylococcus aureus for cultivation. It can be observed that the number of Escherichia coli and Staphylococcus aureus colonies decreased successively, and an inhibition zone was formed near the membrane, indicating that the membrane has a good antibacterial effect. The SEM image of the dense surface of the membrane is shown in Figure 1 shown. Example

[0019] Step 1): Preparation of DA modifier: The substances involved in the synthesis step of DA modifier are composed of the following substances, 2.2 g of polyvinyl alcohol, 50 ml of dimethyl sulfoxide, 9.0 g of D-arginine hydrochloride, and 300 ml of acetone. Mix and dissolve polyvinyl alcohol and dimethyl sulfoxide at 55 °C and adjust the pH to 3 with aqueous sulfuric acid solution. Add the weighed amino acid hydrochloride to the above solution and ultrasonicate for 5 min until completely dissolved; with the help of light-induced technology, irradiate with an ultraviolet lamp with a wavelength of 365 nm for 30 min; stir in an oil bath at 120 °C for 20 h; add acetone solution to the filtrate obtained by vacuum filtration; filter again and perform Soxhlet extraction on the filter residue. Soak the filter residue in acetone extract and siphon at 81 °C until the acetone extract is clear to obtain the DA modifier; vacuum dry and grind into powder; Step 2): The casting solution is prepared from the following components: 15 g of polyethersulfone as the substrate, 45 g of polyethylene glycol (MW=6000) as the pore-forming agent, 0.5 g of DA modified material, and the remaining amount is the solvent N,N-dimethylformamide. Dissolve it in the solvent and then add the pore-forming agent and heat and stir. After dissolving, dissolve the DA modified material prepared in (1) in the solvent and add it, continue stirring until a transparent casting solution is formed, and let it stand for degassing and standby; Step 3) Preparation of modified membrane: Use a scraper with a speed of 10 mm / s to spread the casting liquid in step (2) into a thin layer and then immerse it in a phase transformation liquid for phase transformation. The phase transformation liquid is an ethanol aqueous solution with a volume fraction of 40% ethanol. The thickness of the thin layer formed by spreading the casting liquid is 250 µm. The solidified membrane is washed with pure water until there is no obvious foam in the washing liquid to obtain an antibacterial and anti-fouling high-flux hydrophilic modified polyethersulfone membrane, which is then immersed in a phase transformation liquid for storage.

[0020] The pure water flux of the composite membrane is 630 L·m -2 ·h -1 , BSA retention rate ≥99.2%, polypeptide permeability ≥99.3%. The membrane was placed on the surface of a culture medium containing Gram-negative Escherichia coli and Staphylococcus aureus for culture. It was observed that the colony counts of Escherichia coli and Staphylococcus aureus decreased successively, and an inhibition zone was formed near the membrane, indicating that the membrane had a good antibacterial effect. Example

[0021] Step 1): Preparation of DA modifier: The substances involved in the synthesis step of DA modifier are composed of the following substances, 2.2 g of polyvinyl alcohol, 50 ml of dimethyl sulfoxide, 9.2 g of L-arginine hydrochloride, and 300 ml of acetone. Mix and dissolve polyvinyl alcohol and dimethyl sulfoxide at 60 °C and adjust the pH to 4 with aqueous sulfuric acid. Add the weighed amino acid hydrochloride to the above solution and ultrasonicate for 6 min until completely dissolved; with the help of light-induced technology, irradiate with an ultraviolet lamp with a wavelength of 365 nm for 15 min; stir in an oil bath at 130 °C for 16 h; add acetone solution to the filtrate obtained by vacuum filtration; filter again and perform Soxhlet extraction on the filter residue. Soak the filter residue in acetone extract and siphon at 82 °C until the acetone extract is clear to obtain the DA modifier; vacuum dry and grind into powder; Step 2): The casting solution is prepared from the following components: 17 g of polyethersulfone as the substrate, 43 g of polyethylene glycol (MW=8000) as the pore-forming agent, 0.75 g of DA modified material, and the remaining amount of dimethyl sulfoxide as the solvent. Dissolve it in the solvent and then add the pore-forming agent and heat and stir. After dissolving, dissolve the DA modified material prepared in (1) in the solvent and add it, continue stirring until a transparent casting solution is formed, and let it stand for degassing and standby; Step 3) Preparation of modified membrane: Use a scraper with a speed of 20 mm / s to spread the casting liquid in step (2) into a thin layer and then immerse it in a phase transformation liquid for phase transformation. The phase transformation liquid is an ethanol aqueous solution with a volume fraction of 60% ethanol. The thickness of the thin layer formed by spreading the casting liquid is 175 µm. The solidified membrane is washed with pure water until there is no obvious foam in the washing liquid to obtain an antibacterial and anti-fouling high-flux hydrophilic modified polyethersulfone membrane, which is then immersed in a phase transformation liquid for storage.

[0022] The pure water flux of the composite membrane is 612 L·m -2 ·h -1 , BSA retention rate ≥99.4%, polypeptide permeability ≥99.2%, the membrane was placed on the surface of a culture medium containing Gram-negative Escherichia coli and Staphylococcus aureus for cultivation, and it was observed that the number of Escherichia coli and Staphylococcus aureus colonies decreased successively, and an inhibition zone was formed near the membrane, indicating that the membrane has a good antibacterial effect. The SEM image of the dense surface of the membrane is shown in Figure 2 shown. Example

[0023] Step 1): Preparation of DA modifier: The substances involved in the synthesis step of DA modifier are composed of the following substances, 2.2 g of polyvinyl alcohol, 50 ml of dimethyl sulfoxide, 9.1 g of lysine hydrochloride, and 300 ml of acetone. Mix and dissolve polyvinyl alcohol and dimethyl sulfoxide at 63 °C and adjust the pH to 3.5 with aqueous sulfuric acid solution. Add the weighed amino acid hydrochloride to the above solution and ultrasonicate for 7 min until completely dissolved; with the help of light-induced technology, irradiate with an ultraviolet lamp with a wavelength of 365 nm for 20 min; stir in an oil bath at 125 °C for 24 h; add acetone solution to the filtrate obtained by vacuum filtration; filter again and perform Soxhlet extraction on the filter residue. Soak the filter residue in acetone extract and siphon at 83 °C until the acetone extract is clear to obtain the DA modifier; vacuum dry and grind into powder; Step 2): The casting solution is prepared from the following components: 17 g of polyethersulfone as the substrate, 43 g of polyvinylpyrrolidone as the pore-forming agent, 0.875 g of DA modified material, and the remaining amount of solvent N,N-dimethylacetamide. Dissolve it in the solvent and then add the pore-forming agent and heat and stir. After dissolution, dissolve the DA modified material prepared in (1) in the solvent and add it, continue stirring until a transparent casting solution is formed, and let it stand for degassing and standby; Step 3) Preparation of modified membrane: Use a scraper with a speed of 15 mm / s to spread the casting liquid in step (2) into a thin layer and then immerse it in a phase transformation liquid for phase transformation. The phase transformation liquid is an ethanol aqueous solution with a volume fraction of 80% ethanol. The thickness of the thin layer formed by spreading the casting liquid is 225 µm. The solidified membrane is washed with pure water until there is no obvious foam in the washing liquid to obtain an antibacterial and anti-fouling high-flux hydrophilic modified polyethersulfone membrane, which is then immersed in a phase transformation liquid for storage.

[0024] The pure water flux of the composite membrane is 716 L·m -2 ·h -1 , BSA retention rate ≥99.6%, polypeptide permeability ≥99.3%. The membrane was placed on the surface of a culture medium containing Gram-negative Escherichia coli and Staphylococcus aureus for culture. It was observed that the colony counts of Escherichia coli and Staphylococcus aureus decreased successively, and an inhibition zone was formed near the membrane, indicating that the membrane had a good antibacterial effect. Example

[0025] Step 1): Preparation of DA modifier: The substances involved in the synthesis step of DA modifier are composed of the following substances, 2.2 g of polyvinyl alcohol, 50 ml of dimethyl sulfoxide, 9.1 g of D-arginine hydrochloride, and 300 ml of acetone. Mix and dissolve polyvinyl alcohol and dimethyl sulfoxide at 64 °C and adjust the pH to 3.3 with aqueous sulfuric acid solution. Add the weighed amino acid hydrochloride to the above solution and ultrasonicate for 10 min until completely dissolved; with the help of light-induced technology, irradiate with an ultraviolet lamp with a wavelength of 365 nm for 20 min; stir in an oil bath at 120-130 °C for 24 h; add acetone solution to the filtrate obtained by vacuum filtration; filter again and perform Soxhlet extraction on the residue. Soak the residue in acetone extract and siphon at 83 °C until the acetone extract is clear to obtain the DA modifier; vacuum dry and grind into powder; Step 2): The casting solution is prepared from the following components: 20 g of polyethersulfone as the substrate, 40 g of polyethylene glycol (MW=400) as the pore-forming agent, 1 g of DA modified material, and the remaining amount is solvent N-methylpyrrolidone. Dissolve it in the solvent and then add the pore-forming agent and heat and stir. After dissolving, dissolve the DA modified material prepared in (1) in the solvent and add it, continue stirring until a transparent casting solution is formed, and let it stand for degassing and standby; Step 3) Preparation of modified membrane: Use a scraper with a speed of 25 mm / s to spread the casting liquid in step (2) into a thin layer and then immerse it in a phase transformation liquid for phase transformation, the phase transformation liquid is ethanol. The thickness of the thin layer formed by spreading the casting liquid is 250µm. The solidified membrane is washed with pure water until there is no obvious foam in the washing liquid to obtain an antibacterial and anti-fouling high-flux hydrophilic modified polyethersulfone membrane, which is then immersed in a phase transformation liquid for storage.

[0026] The pure water flux of the composite membrane is 646 L·m -2 ·h -1 , BSA retention rate ≥99.5%, polypeptide permeability ≥99.3%. The membrane was placed on the surface of a culture medium containing Gram-negative Escherichia coli and Staphylococcus aureus for cultivation. It can be observed that the number of Escherichia coli and Staphylococcus aureus colonies decreased successively, and an inhibition zone was formed near the membrane, indicating that the membrane has a good antibacterial effect. The SEM image of the dense surface of the membrane is shown in Figure 3 shown. Example

[0027] Step 1): Preparation of DA modifier: The substances involved in the synthesis step of DA modifier are composed of the following substances, 2.2 g of polyvinyl alcohol, 50 ml of dimethyl sulfoxide, 9.1 g of D-arginine hydrochloride, and 300 ml of acetone. Mix and dissolve polyvinyl alcohol and dimethyl sulfoxide at 60 °C and adjust the pH to 3.5 with aqueous sulfuric acid solution. Add the weighed amino acid hydrochloride to the above solution and ultrasonicate for 10 min until completely dissolved; with the help of light-induced technology, irradiate with an ultraviolet lamp with a wavelength of 365 nm for 20 min; stir in an oil bath at 123 °C for 24 h; add acetone solution to the filtrate obtained by vacuum filtration; filter again and perform Soxhlet extraction on the residue. Soak the residue in acetone extract and siphon at 83 °C until the acetone extract is clear to obtain the DA modifier; vacuum dry and grind into powder; Step 2): The casting solution is prepared from the following components: 17 g of polyethersulfone as the substrate, 43 g of polyethylene glycol (MW=400) as the pore-forming agent, 0.75 g of DA modified material, and the remaining amount of solvent N,N-dimethylacetamide. Dissolve it in the solvent and then add the pore-forming agent and heat and stir. After dissolving, dissolve the DA modified material prepared in (1) in the solvent and add it, continue stirring until a transparent casting solution is formed, and let it stand for degassing and standby; Step 3) Preparation of modified membrane: Use a scraper with a speed of 18 mm / s to spread the casting liquid in step (2) into a thin layer and then immerse it in a phase transformation liquid for phase transformation. The phase transformation liquid is an ethanol aqueous solution with a volume fraction of 20% ethanol. The thickness of the thin layer formed by spreading the casting liquid is 200 µm. The solidified membrane is washed with pure water until there is no obvious foam in the washing liquid to obtain an antibacterial and anti-fouling high-flux hydrophilic modified polyethersulfone membrane, which is then immersed in a phase transformation liquid for storage.

[0028] The pure water flux of the composite membrane is 612 L·m -2 ·h -1 , BSA retention rate ≥99.6%, polypeptide permeability ≥99.8%. The membrane was placed on the surface of a culture medium containing Gram-negative Escherichia coli and Staphylococcus aureus for culture. It was observed that the colony counts of Escherichia coli and Staphylococcus aureus decreased successively, and an inhibition zone was formed near the membrane, indicating that the membrane had a good antibacterial effect. Example

[0029] Step 1): Preparation of DA modifier: The substances involved in the synthesis step of DA modifier are composed of the following substances, 2.2 g of polyvinyl alcohol, 50 ml of dimethyl sulfoxide, 9.1 g of D-arginine hydrochloride, and 300 ml of acetone. Mix and dissolve polyvinyl alcohol and dimethyl sulfoxide at 65 °C and adjust the pH to 3.5 with aqueous sulfuric acid solution. Add the weighed amino acid hydrochloride to the above solution and ultrasonicate for 10 min until completely dissolved; with the help of light-induced technology, irradiate with an ultraviolet lamp with a wavelength of 365 nm for 20 min; stir in an oil bath at 128 °C for 24 h; add acetone solution to the filtrate obtained by vacuum filtration; filter again and perform Soxhlet extraction on the residue. Soak the residue in acetone extract and siphon at 83 °C until the acetone extract is clear to obtain the DA modifier; vacuum dry and grind into powder; Step 2): The casting solution is prepared from the following components: 17 g of polyethersulfone as the substrate, 43 g of polyethylene glycol (MW=400) as the pore-forming agent, 0.5 g of DA modified material, and the remaining amount of solvent N,N-dimethylacetamide. Dissolve it in the solvent and then add the pore-forming agent and heat and stir. After dissolving, dissolve the DA modified material prepared in (1) in the solvent and add it, continue stirring until a transparent casting solution is formed, and let it stand for degassing and standby; Step 3) Preparation of modified membrane: Use a scraper with a speed of 30 mm / s to spread the casting liquid in step (2) into a thin layer and then immerse it in a phase transformation liquid for phase transformation. The phase transformation liquid is an ethanol aqueous solution with a volume fraction of 20% ethanol. The thickness of the thin layer formed by spreading the casting liquid is 200 µm. The solidified membrane is washed with pure water until there is no obvious foam in the washing liquid to obtain an antibacterial and anti-fouling high-flux hydrophilic modified polyethersulfone membrane, which is then immersed in a phase transformation liquid for storage.

[0030] The pure water flux of the composite membrane is 675 L·m -2 ·h -1 , BSA retention rate ≥99.6%, polypeptide permeability ≥99.3%. The membrane was placed on the surface of a culture medium containing Gram-negative Escherichia coli and Staphylococcus aureus for culture. It was observed that the colony counts of Escherichia coli and Staphylococcus aureus decreased successively, and an inhibition zone was formed near the membrane, indicating that the membrane had a good antibacterial effect. Example

[0031] Step 1): Preparation of DA modifier: The substances involved in the synthesis step of DA modifier are composed of the following substances, 2.2 g of polyvinyl alcohol, 50 ml of dimethyl sulfoxide, 9.1 g of D-arginine hydrochloride, and 300 ml of acetone. Mix and dissolve polyvinyl alcohol and dimethyl sulfoxide at 58 °C and adjust the pH to 3.5 with aqueous sulfuric acid solution. Add the weighed amino acid hydrochloride to the above solution and ultrasonicate for 10 min until completely dissolved; with the help of light-induced technology, irradiate with an ultraviolet lamp with a wavelength of 365 nm for 20 min; stir in an oil bath at 122 °C for 24 h; add acetone solution to the filtrate obtained by vacuum filtration; filter again and perform Soxhlet extraction on the filter residue. Soak the filter residue in acetone extract and siphon at 83 °C until the acetone extract is clear to obtain the DA modifier; vacuum dry and grind into powder; Step 2): The casting solution is prepared from the following components: 17 g of polyethersulfone as the substrate, 43 g of polyethylene glycol (MW=6000) as the pore-forming agent, 1 g of DA modified material, and the remaining amount of solvent N,N-dimethylacetamide. Dissolve it in the solvent and then add the pore-forming agent and heat and stir. After dissolving, dissolve the DA modified material prepared in (1) in the solvent and add it, continue stirring until a transparent casting solution is formed, and let it stand for degassing and standby; Step 3) Preparation of modified membrane: Use a scraper with a speed of 30 mm / s to spread the casting liquid in step (2) into a thin layer and then immerse it in a phase transformation liquid for phase transformation. The phase transformation liquid is an ethanol aqueous solution with a volume fraction of 20%. The thickness of the thin layer formed by spreading the casting liquid is 150 µm. The solidified membrane is washed with pure water until there is no obvious foam in the washing liquid to obtain an antibacterial and anti-fouling high-flux hydrophilic modified polyethersulfone membrane, which is then immersed in a phase transformation liquid for storage.

[0032] The pure water flux of the composite membrane is about 800 L·m -2 ·h -1 , BSA retention rate ≥99.8%, polypeptide permeability ≥99.5%. The membrane was placed on the surface of a culture medium containing Gram-negative Escherichia coli and Staphylococcus aureus for culture. It was observed that the colony counts of Escherichia coli and Staphylococcus aureus decreased successively, and an inhibition zone was formed near the membrane, indicating that the membrane had a good antibacterial effect.

[0033] Table 1 Comparison of the flux, macromolecular impurity retention rate and polypeptide permeability of the embodiments of the present invention and the currently available ultrafiltration membranes Ultrafiltration membrane product name <![CDATA[Pure water flux L·m -2 ·h -1 > Retention rate of macromolecular impurities (taking bovine serum albumin as an example) Peptide penetration Liter 200-280 ≥90.0% ≥97.0% DuPont 260-300 ≥95.0% ≥95.0% Koch 240-310 ≥92.0% ≥96.0% Hyde Energy 235-310 ≥95.0% ≥98.0% The present invention 600-800 ≥99.0% ≥99.0%

Claims

1. A method for preparing an antibacterial and anti-pollution high-throughput polyethersulfone membrane for polypeptide separation and purification, characterized in that: The following steps are involved: (1) Synthesis of DA modifier: The substances involved in the synthesis step of DA modifier are composed of the following mass percentages: 0.5-2% polyvinyl alcohol, 12.5-20% dimethyl sulfoxide, 2-3% amino acid hydrochloride, and 75-85% acetone. Mix and dissolve polyvinyl alcohol and dimethyl sulfoxide at 55-65°C and adjust the pH to 3-4 with aqueous sulfuric acid. Add the weighed amino acid hydrochloride to the above solution and ultrasonicate for 5-10 min until it is completely dissolved; with the help of light-induced technology, irradiate with a UV lamp with a wavelength of 365 nm for 15-30 min; stir in an oil bath at 120-130°C for 16-24 h; add acetone solution to the filtrate obtained by vacuum filtration; filter again and perform Soxhlet extraction on the residue. Soak the residue in acetone extract and siphon at 80-84°C until the acetone extract is clear to obtain the DA modifier; vacuum dry and grind into powder; (2) Preparation of casting solution: The casting solution is prepared by the following components in percentage by mass: 15-20% of substrate, 40-60% of pore-forming agent, 0.25-1% of DA modified material, and the remainder is solvent. The substrate is polyethersulfone, which is dissolved in the solvent and then the pore-forming agent is added and heated and stirred. After dissolution, the DA modified material prepared in (1) is dissolved in the solvent and added, and stirring is continued until a transparent casting solution is formed, and then allowed to stand for degassing and standby; (3) Preparation of an antibacterial and antifouling high-throughput polyethersulfone membrane for peptide separation and purification: Use a scraper to spread the casting solution in step (2) into a thin layer and then immerse it in a phase inversion solution for phase inversion. The thickness of the thin layer formed by spreading the casting solution is 150-250 µm. The solidified membrane is washed with pure water until there is no obvious foam in the washing solution to obtain an antibacterial and antifouling high-throughput hydrophilic modified polyethersulfone membrane, which is then immersed in a phase inversion solution for storage.

2. The method for preparing an antibacterial and anti-pollution high-throughput hydrophilic modified polyethersulfone membrane according to claim 1, characterized in that: The main reactant of the synthetic modifier is one of D-arginine hydrochloride, L-arginine hydrochloride and lysine hydrochloride.

3. The preparation of the casting solution according to claim 1: the pore-forming agent is one of polyethylene glycol (MW = 400-8000), hydroxypropyl cellulose and polyvinyl pyrrolidone.

4. The preparation of the casting solution according to claim 1: the solvent is one of N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone.

5. Preparation of the antibacterial and anti-fouling high-throughput hydrophilic modified polyethersulfone membrane according to claim 1: the scraper speed is set to 10-30 mm / s.

6. The preparation of the antibacterial and anti-pollution high-throughput hydrophilic modified polyethersulfone membrane according to claim 1: the phase conversion liquid is one of ethanol aqueous solutions with an ethanol volume fraction of 0%, 20%, 40%, 60%, 80%, and 100%.

7. The method for preparing an antibacterial and anti-fouling high-flux polyethersulfone membrane for polypeptide separation and purification according to any one of claims 1 to 5, wherein the prepared antibacterial and anti-fouling high-flux polyethersulfone membrane for polypeptide separation and purification is characterized in that: The pure water flux of the composite membrane is 600-800 L·m -2 ·h -1 , bovine serum albumin retention rate ≥99%, polypeptide permeability ≥95%, and has obvious antibacterial effect.

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