Ultrafiltration membrane based on metalloporphyrin modification

Abstract

The invention discloses a hydrophilic polyethersulfone ultrafiltration membrane based on metalloporphyrin coordination modification as well as a preparation method and application of the hydrophilic polyethersulfone ultrafiltration membrane. According to the ultrafiltration membrane, a membrane casting solution is prepared by blending a polyether sulfone base material, an organic solvent, a pore-foaming agent and tetra (4-aminophenyl) porphyrin, and the membrane casting solution is cured and formed in a coagulating bath containing ferric ions through a phase inversion process. The preparation method is characterized in that porphyrin compounds and iron ions are subjected to an in-situ coordination reaction in the phase inversion process to form a stable metalloporphyrin complex network structure, and the prepared ultrafiltration membrane has the following advantages that the hydrophilicity is increased, and the pure water flux is increased; the protein rejection rate is not less than 95%; the antibacterial property and the anti-pollution property are excellent. The process is simple and controllable, and the obtained membrane material has important application value in the field of biological medicine separation.

Description

Technical Field

[0001] The present invention relates to a hydrophilic ultrafiltration membrane, particularly a metalloporphyrin-modified ultrafiltration membrane with high protein retention, belonging to the technical field of polymer separation membranes. Through a specific modification process, this ultrafiltration membrane combines high-purity water flux, excellent selectivity, and good anti-fouling and antibacterial properties, making it widely applicable to protein separation and purification processes in the biopharmaceutical field. Background Art

[0002] In recent years, the rapid development of genetic engineering technology has greatly promoted the research, development, and production of peptide and protein biopharmaceuticals. These bioactive molecules have demonstrated significant application value in areas such as drug development, vaccine preparation, and clinical diagnostics. However, the separation and purification of protein products still faces significant technical bottlenecks. Traditional purification methods, such as salting out, gel filtration, isoelectric precipitation, and affinity chromatography, generally suffer from high energy and water consumption, complex operations, and other issues, resulting in high production costs.

[0003] Membrane separation technology, due to its high efficiency and energy-saving characteristics, offers a promising solution for protein purification. Polyethersulfone (PES), a thermoplastic polymer with excellent performance, can be used to prepare porous ultrafiltration membranes through a phase inversion method. PES membranes are widely used in bioseparation due to their outstanding antioxidant properties, thermal stability, and mechanical strength. However, the inherent hydrophobicity of PES makes the membrane surface susceptible to protein fouling, leading to a series of problems such as decreased flux, increased energy consumption, and shortened service life. Therefore, there is an urgent need to improve the hydrophobicity of PES ultrafiltration membranes through material modification techniques.

[0004] Prior research on hydrophilic modification of PES membranes has primarily focused on optimizing a single property, such as improving antifouling resistance or increasing flux, but has struggled to simultaneously achieve high protein retention, high flux, and long-lasting antimicrobial performance. In particular, there are relatively few reports on PES membranes that simultaneously optimize both protein retention and pure water flux, limiting their application in high-end bioseparation applications.

[0005] Tetrakis(4-aminophenyl)porphyrin (TAPP) is a functional porphyrin derivative with a unique structure, containing four aminophenyl groups within its molecule. The amino groups of TAPP can construct a hydrophilic network on the membrane surface through hydrogen bonding, effectively reducing hydrophobic interactions between proteins and the membrane surface, thereby reducing nonspecific adsorption and significantly improving the membrane's anti-fouling properties and long-term stability. Furthermore, TAPP's rigid molecular structure inhibits rapid polymer aggregation during phase separation, inducing the formation of a more uniform microporous structure, optimizing pore size distribution, and achieving a balance between water flux and retention accuracy. The hydrogen bonding between the amino groups and the PES molecular chains also slows the phase separation kinetics, promoting the formation of a denser cortex and a more open support layer, thereby enhancing the membrane's permselectivity. Furthermore, the amino groups, acting as active sites, can be used to introduce other functional groups through chemical reactions such as acylation, cross-linking, grafting, or coordination, further optimizing the membrane's overall performance.

[0006] This invention innovatively introduces a porphyrin compound into the membrane system and adds a specific concentration of trivalent iron ions to the coagulation bath to form a metalloporphyrin complex. This complex effectively modulates the membrane pore structure during film formation, resulting in a modified ultrafiltration membrane that exhibits both excellent protein retention and high water flux, as well as long-lasting antifouling and antibacterial properties. This technological breakthrough provides new insights into the design and preparation of high-performance protein separation membranes. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide an ultrafiltration membrane modified based on metalloporphyrin to improve the current situation in which the protein retention and pure water flux of the ultrafiltration membrane cannot be optimized simultaneously in the existing process.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is: an ultrafiltration membrane based on metalloporphyrin modification, the specific steps of which are as follows: (1) Preparation of casting solution Calculated by mass percentage, 15-20% of the substrate, 15-30% of the porogen, and 1-10% of the porphyrin compound are dissolved in the remaining solvent, stirred at 60-80° C. for 6-12 hours to form a homogeneous transparent solution, and allowed to stand for degassing; (2) Preparation of coagulation bath Dissolve ferric chloride in deionized water and adjust the Fe³⁺ concentration to 200-500 mmol / L; (3) Film forming process The casting liquid was scraped onto a glass plate at a speed of 30-50 mm / s to form a 100-250 μm liquid film. After pre-evaporation for 5-105 s in a 50-80% humidity environment, the film was immersed in a coagulation bath for curing for 10-50 min and washed with deionized water to obtain a composite ultrafiltration membrane.

[0009] Preferably, the porogen is one of polyethylene glycol (MW=400-8000), hydroxypropyl cellulose, and polyvinyl pyrrolidone.

[0010] Preferably, the substrate is one of polysulfone, polyethersulfone, polyphenylsulfone, sulfonated polyethersulfone or polyacrylonitrile.

[0011] Preferably, the blended material for forming the metal porphyrin complex is one of tetracarboxyphenylporphyrin, meso-tetrakis-(4-(Boc-threonine)aminophenyl)porphyrin, and tetrakis(4-aminophenyl)porphyrin.

[0012] Preferably, the solvent is one of N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone.

[0013] The invention discloses an ultrafiltration membrane based on metalloporphyrin modification, characterized in that an Fe-porphyrin coordination structure exists on the surface; the pure water flux is ≥1800 L·m -2 ·h -1 bar -1 ; Molecular weight cut-off 30-55 kDa; Protein retention rate ≥95%. Beneficial effects

[0014] This invention innovatively introduces tetrakis(4-aminophenyl)porphyrin (TAPP) into a polyethersulfone (PES) membrane system. Combined with the coordination effect of trivalent iron (Fe³⁺), a modified PES ultrafiltration membrane with a unique structure was successfully prepared using a non-solvent-induced phase separation method. During the phase inversion process, TAPP molecules react with Fe³⁺ to form a stable metalloporphyrin complex (Fe-TAPP), which simultaneously migrates toward the membrane surface driven by chemical potential. This unique migration behavior results in a more compact arrangement of the PES polymer segments, significantly optimizing the membrane pore structure, as demonstrated by the following: (1) Optimization of finger-shaped pore structure The finger-like pores inside the membrane are more regular in shape and the pore size distribution is more uniform, forming a more open porous structure, reducing ineffective pores, and improving mass transfer efficiency. The optimized pore structure significantly increases pure water flux and reduces operating energy consumption.

[0015] (2) Excellent protein retention rate A denser separation layer is formed on the membrane surface, enhancing the efficient retention of target proteins.

[0016] (3) Long-lasting anti-pollution performance The amino groups of TAPP enhance the hydrophilicity of the membrane surface and reduce protein adsorption. The Fe-TAPP complex inhibits microbial growth by releasing metal ions, thereby extending the service life of the membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Cross-sectional SEM image of the modified membrane of Example 3 of the present invention DETAILED DESCRIPTION

[0018] The present invention will be further described below with reference to specific embodiments. Example

[0019] Step 1): Preparation of casting solution: by mass percentage, 15% polyethersulfone, 30% polyethylene glycol (MW = 400), 1% tetrakis (4-aminophenyl) porphyrin is dissolved in the balance solvent N, N-dimethylacetamide; stirring at 60 ° C for 12 hours to form a homogeneous transparent solution, and standing to degas; Step 2): Preparation of coagulation bath: dissolve ferric chloride in deionized water and adjust the Fe³⁺ concentration to 300 mmol / L; Step 3) Membrane Formation: The casting solution was applied to a glass plate at a speed of 30 mm / s to form a 250 μm film. After pre-evaporation for 55 seconds in a 50% humidity environment, the film was immersed in a coagulation bath for 10 minutes and then washed with deionized water to obtain a composite ultrafiltration membrane. The composite membrane had a pure water flux of 1600 L·m -2 ·h -1 , protein retention rate>99.7%. The molecular weight cut-off reaches 45kDa, and the flux recovery rate reaches 95%. Example

[0020] Step 1): Preparation of casting solution: by mass percentage, polyethersulfone 16%, polyethylene glycol (MW = 400) 25%, tetrakis (4-aminophenyl) porphyrin 2% is dissolved in the balance solvent N, N-dimethylacetamide; stir at 70 ° C for 12 hours to form a homogeneous transparent solution, and stand to degas; Step 2): Preparation of coagulation bath: dissolve ferric chloride in deionized water and adjust the Fe³⁺ concentration to 200 mmol / L; Step 3) Membrane Formation: The casting solution was applied to a glass plate at a speed of 40 mm / s to form a 250 μm film. After pre-evaporation for 65 seconds in a 60% humidity environment, the film was immersed in a coagulation bath for 20 minutes and then washed with deionized water to obtain a composite ultrafiltration membrane. The pure water flux of the composite membrane was 1400 L·m -2 ·h -1 The protein retention rate is >98.7%, the molecular weight cut-off reaches 40kDa, and the flux recovery rate reaches 96%. Example

[0021] Step 1): Preparation of casting solution: by mass percentage, polyethersulfone 17%, polyethylene glycol (MW = 400) 20%, tetrakis (4-aminophenyl) porphyrin 3% is dissolved in the balance solvent N, N-dimethylacetamide; stirring at 80 ° C for 10 hours to form a homogeneous transparent solution, and standing to degas; Step 2): Preparation of coagulation bath: dissolve ferric chloride in deionized water and adjust the Fe³⁺ concentration to 250 mmol / L; Step 3) Membrane Formation: The casting solution was applied to a glass plate at a speed of 50 mm / s to form a 250 μm film. After pre-evaporation for 70 seconds in a 70% humidity environment, the film was immersed in a coagulation bath for 15 minutes and then washed with deionized water to obtain a composite ultrafiltration membrane. The pure water flux of the composite membrane was 1500 L·m -2 ·h -1 , protein retention rate>97.8%. The molecular weight cut-off reaches 35kDa, and the flux recovery rate reaches 92%. Example

[0022] Step 1): Preparation of casting solution: by mass percentage, polyethersulfone 17%, polyethylene glycol (MW = 400) 22%, tetrakis (4-aminophenyl) porphyrin 3% is dissolved in the balance solvent N, N-dimethylacetamide; stir at 60 ° C for 12 hours to form a homogeneous transparent solution, and stand to degas; Step 2): Preparation of coagulation bath: dissolve ferric chloride in deionized water and adjust the Fe³⁺ concentration to 350 mmol / L; Step 3) Membrane Formation: The casting solution was applied to a glass plate at a speed of 45 mm / s to form a 250 μm film. After pre-evaporation for 68 seconds in a 65% humidity environment, the film was immersed in a coagulation bath for 22 minutes and then washed with deionized water to obtain a composite ultrafiltration membrane. The pure water flux of the composite membrane was 1450 L·m -2 ·h -1 , protein retention rate>98.8%. The molecular weight cut-off reaches 50kDa, and the flux recovery rate reaches 94%. Example

[0023] Step 1): Preparation of casting solution: by mass percentage, polyethersulfone 18%, polyethylene glycol (MW = 400) 23%, tetrakis (4-aminophenyl) porphyrin 4% is dissolved in the balance solvent N, N-dimethylacetamide; stirring at 80 ° C for 10 hours to form a homogeneous transparent solution, and standing to degas; Step 2): Preparation of coagulation bath: dissolve ferric chloride in deionized water and adjust the Fe³⁺ concentration to 280 mmol / L; Step 3) Membrane Formation: The casting solution was applied to a glass plate at a speed of 50 mm / s to form a 250 μm film. After pre-evaporation for 66 seconds in a 75% humidity environment, the film was immersed in a coagulation bath for 12 minutes and then washed with deionized water to obtain a composite ultrafiltration membrane. The pure water flux of the composite membrane was 1680 L·m -2 ·h -1 , protein retention rate>97.8%. The molecular weight cut-off reaches 55kDa, and the flux recovery rate reaches 93%. Example

[0024] Step 1): Preparation of casting solution: by mass percentage, polyethersulfone 18%, polyethylene glycol (MW = 400) 23%, tetrakis (4-aminophenyl) porphyrin 4% is dissolved in the balance solvent N, N-dimethylacetamide; stir at 70 ° C for 11 hours to form a homogeneous transparent solution, and stand to degas; Step 2): Preparation of coagulation bath: Dissolve ferric chloride in deionized water and adjust the Fe³⁺ concentration to 400 mmol / L; Step 3) Membrane forming process: The casting solution was applied to a glass plate at a speed of 50 mm / s to form a 250 μm film. After pre-evaporation for 68 seconds in a 70% humidity environment, the film was immersed in a coagulation bath for 15 minutes and then washed with deionized water to obtain a composite ultrafiltration membrane. The pure water flux of the composite membrane was 1650 L·m- 2 ·h -1 , protein retention rate>96.9%. The molecular weight cut-off reaches 45kDa, and the flux recovery rate reaches 95%. Example

[0025] Step 1): Preparation of casting solution: by mass percentage, 18% polyethersulfone, 25% polyethylene glycol (MW = 400), 5% tetrakis (4-aminophenyl) porphyrin is dissolved in the balance solvent N, N-dimethylacetamide; stirring at 80 ° C for 6 hours to form a homogeneous transparent solution, and standing to degas; Step 2): Preparation of coagulation bath: Dissolve ferric chloride in deionized water and adjust the Fe³⁺ concentration to 450 mmol / L; Step 3) Membrane Formation: The casting solution was applied to a glass plate at a speed of 35 mm / s to form a 250 μm film. After pre-evaporation for 60 seconds in a 55% humidity environment, the film was immersed in a coagulation bath for 25 minutes and then washed with deionized water to obtain a composite ultrafiltration membrane. The pure water flux of the composite membrane was 1550 L·m -2 ·h -1 , protein retention rate>97.6%. The molecular weight cut-off reaches 35kDa, and the flux recovery rate reaches 97%. Example

[0026] Step 1): Preparation of casting solution: by mass percentage, polyethersulfone 19%, polyethylene glycol (MW = 400) 27%, tetrakis (4-aminophenyl) porphyrin 6% is dissolved in the balance solvent N, N-dimethylacetamide; stirring at 80 ° C for 8 hours to form a homogeneous transparent solution, and standing to degas; Step 2): Preparation of coagulation bath: dissolve ferric chloride in deionized water and adjust the Fe³⁺ concentration to 500 mmol / L; Step 3) Membrane Formation: The casting solution was applied to a glass plate at a speed of 50 mm / s to form a 250 μm film. After pre-evaporation for 67 seconds in a 55% humidity environment, the film was immersed in a coagulation bath for 10 minutes and then washed with deionized water to obtain a composite ultrafiltration membrane. The pure water flux of the composite membrane was 1450 L·m -2 ·h -1 , protein retention rate>96.8%. The molecular weight cut-off reaches 45kDa, and the flux recovery rate reaches 95%.

Claims

1. A method for preparing an ultrafiltration membrane modified with metalloporphyrin, characterized in that The following steps are involved: (1) Preparation of casting solution Calculated by mass percentage, 15-20% of the substrate, 15-30% of the porogen, and 1-10% of the porphyrin compound are dissolved in the remaining solvent, stirred at 60-80° C. for 6-12 hours to form a homogeneous transparent solution, and allowed to stand for degassing; (2) Preparation of coagulation bath Dissolve ferric chloride in deionized water and adjust the Fe³⁺ concentration to 200-500 mmol / L; (3) Film forming process The casting liquid was scraped onto a glass plate at a speed of 30-50 mm / s to form a 100-250 μm liquid film. After pre-evaporation for 5-105 s in a 50-80% humidity environment, the film was immersed in a coagulation bath for curing for 10-50 min and washed with deionized water to obtain a composite ultrafiltration membrane.

2. The method according to claim 1, wherein: The porogen is polyethylene glycol (M W =400-8000), hydroxypropyl cellulose or polyvinyl pyrrolidone.

3. The method according to claim 1, wherein: The substrate is selected from polysulfone, polyethersulfone, polyphenylsulfone, sulfonated polyethersulfone or polyacrylonitrile.

4. The method according to claim 1, wherein: The porphyrin compound is selected from tetracarboxyphenylporphyrin, meso-tetrakis-(4-(Boc-threonine)aminophenyl)porphyrin or tetrakis(4-aminophenyl)porphyrin.

5. The method according to claim 1, wherein: The solvent is N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide or N-methylpyrrolidone.

6. A hydrophilic polyethersulfone ultrafiltration membrane prepared by the method according to any one of claims 1 to 5, characterized in that: There is an Fe-porphyrin coordination structure on the surface; pure water flux ≥1800 L·m -2 ·h -1 bar -1 ; Molecular weight cut-off 30-55 kDa; Protein retention rate ≥95%.

7. Use of the ultrafiltration membrane according to claim 6 in biomacromolecule separation, protein concentration or wastewater treatment.

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