Antibacterial nanofiber hemodialysis membrane and method of making the same

Abstract

The application discloses an antibacterial nanofiber hemodialysis membrane and a preparation method thereof, and relates to the technical field of dialysis membranes, and comprises the following process: a surface treatment agent is obtained by mixing a chitosan derivative, heparin, dopamine, an unsaturated monomer and an initiator in a DMF / phosphate buffer mixture; a polyethersulfone nanofiber membrane is taken as a support layer, the surface treatment agent is impregnated, UV irradiation is performed, and a functional layer is formed to obtain a dialysis membrane. The application compounding cerium tris-acrylate phenanthroline hybrid CeO2, N-vinyl pyrrolidone, sodium p-styrene sulfonate and lauryl methacrylate as the unsaturated monomer, compounding the chitosan derivative, heparin and dopamine to prepare the surface treatment agent, impregnating the polyethersulfone nanofiber membrane, and performing irradiation and solidification to form the functional layer, the prepared hemodialysis membrane has high efficient anticoagulation and broad-spectrum antibacterial property, high permeability, low protein adsorption and long-term stability.

Description

Technical Field

[0001] This invention relates to the field of dialysis membrane technology, specifically to an antibacterial nanofiber hemodialysis membrane and its preparation method. Background Technology

[0002] Due to the decline in kidney function in patients with chronic kidney disease, endogenous and exogenous toxins cannot be properly excreted, leading to their accumulation in the blood. This can affect the normal function of various tissues and organs, resulting in uremia syndrome. Hemodialysis is an extracorporeal blood purification technology that removes various harmful and excess metabolic wastes and excess electrolytes from the body through diffusion and convection, achieving the purpose of purifying the blood and correcting water, electrolyte, and acid-base imbalances. During dialysis, blood and dialysate exchange substances within the dialyzer through contact with a semi-permeable membrane and concentration gradients. This causes metabolic wastes and excess electrolytes in the blood to move into the dialysate, while calcium ions and bases in the dialysate move into the blood. The hemodialysis membrane is the core component of the hemodialysis machine and plays a crucial role in the hemodialysis process; its mainstream materials include cellulose, polysulfone, polyethersulfone, polymethyl methacrylate, ethylene vinyl alcohol copolymer, and polyacrylonitrile. Hemodialysis centers are high-risk locations for hospital-acquired infections (especially bloodborne infectious diseases); dialysis patients often have characteristics such as immune system disorders and weakened immune function, making them prone to nosocomial infections and inflammatory reactions. Therefore, we propose an antibacterial nanofiber hemodialysis membrane and its preparation method. Summary of the Invention

[0003] The purpose of this invention is to provide an antibacterial nanofiber hemodialysis membrane and its preparation method, so as to solve the problems mentioned in the background art.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: an antibacterial nanofiber hemodialysis membrane, comprising a support layer and a functional layer;

[0005] Furthermore, the support layer is a polyethersulfone nanofiber membrane.

[0006] Furthermore, the functional layer is formed by impregnating a polyethersulfone nanofiber membrane with a surface treatment agent and then curing it.

[0007] Furthermore, the surface treatment agent includes the following components: sulfonated chitosan, heparin, dopamine, unsaturated monomer, and initiator.

[0008] Furthermore, the unsaturated monomer includes one or more of methyl methacrylate, vinyltriethoxysilane, N-isopropylacrylamide, methacrylic acid, styrene, N-vinylpyrrolidone, sodium p-styrenesulfonate, lauryl methacrylate, and acrylic acid-rare earth derivatives.

[0009] Furthermore, the acrylic acid-rare earth derivative is cerium phenanthroline triacrylate hybridized CeO2.

[0010] In the above technical solution, the support layer is a polyethersulfone nanofiber membrane prepared by electrospinning, which has high porosity and interconnected pores, which can significantly improve water flux and promote the diffusion and removal of medium molecular toxins; it also has good acid and alkali resistance, high temperature resistance, oxidation resistance and biocompatibility, and has a certain mechanical strength.

[0011] A method for preparing an antibacterial nanofiber hemodialysis membrane includes the following processes:

[0012] Sulfonated chitosan, heparin, dopamine, unsaturated monomers, and initiators are mixed in a DMF / phosphate buffer solution to obtain a surface treatment agent.

[0013] A polyethersulfone nanofiber membrane was used as a support layer, impregnated with a surface treatment agent, and then irradiated with UV light to form a functional layer, thus obtaining a dialysis membrane.

[0014] Furthermore, the surface treatment agent comprises the following components by weight: 5-8 parts sulfonated chitosan, 3-5 parts heparin, 2-3 parts dopamine, 20-40 parts unsaturated monomer, and 1-2 parts photoinitiator.

[0015] Furthermore, the unsaturated monomer comprises the following components by mass: 8-10 parts N-vinylpyrrolidone, 4-6 parts sodium p-styrenesulfonate, 1-2 parts cerium phenanthroline triacrylate hybrid CeO2, and 2.4-3.0 parts lauryl methacrylate.

[0016] Furthermore, the concentration of the surface treatment agent is 15–20 wt%;

[0017] The volume ratio of DMF to phosphate buffer (PBS, pH 7.4) in the mixture is 6:4.

[0018] Furthermore, the photoinitiator is benzophenone.

[0019] In the above technical solution, sulfonated chitosan provides negatively charged anticoagulant and antibacterial groups, exhibiting anticoagulant and antibacterial adhesion effects. Heparin synergistically enhances the anticoagulant effect and improves anti-Xa activity through the sulfonic acid groups of sulfonated chitosan. Dopamine (hydrochloride), as an adhesion promoter, strengthens the bonding force between the functional layer and the support layer by forming hydrogen bonds / π-π stacking with the support layer through catechol groups.

[0020] N-Vinylpyrrolidone, as a hydrophilic monomer, can reduce protein adsorption and indirectly reduce bacterial adhesion. Sodium p-styrenesulfonate can increase the surface negative charge density, interfere with bacterial cell membrane potential, inhibit metabolism, further enhance anticoagulant activity, and improve the clearance rate of medium-molecular-weight toxins (such as β2-microglobulin). Lauryl methacrylate, as a hydrophobic modifier, regulates surface microphase separation, balances hydrophilicity, prevents excessive swelling, and maintains membrane structural stability. Its hydrophobic long chain (C12) inserts into the bacterial membrane, inducing structural disintegration and improving the antibacterial ability of the functional layer. Ce-TAP@CeO2, as an antibacterial / antioxidant multifunctional filler, improves the antibacterial rate and ROS clearance rate of the functional layer. The photoinitiator benzophenone initiates the free radical polymerization of unsaturated monomers to form a functional layer with an interpenetrating three-dimensional network structure.

[0021] Furthermore, in the impregnation process, the impregnation ratio of polyethersulfone nanofiber membrane and surface treatment agent is 1g:10-15mL; the impregnation time is 5-10min; and the pressure of the extrusion roller is 0.1-0.3MPa.

[0022] Furthermore, the UV irradiation process conditions are: wavelength 365nm, light intensity 5–8mW / cm². 2 Irradiate for 5–10 minutes; then at a wavelength of 365 nm and a light intensity of 12–18 mW / cm². 2 Irradiate for 12–20 minutes.

[0023] Furthermore, the layer is dried after UV irradiation, and the thickness of the functional layer after drying is 20% to 30% of the thickness of the support layer.

[0024] In the above technical solution, the catechol groups of dopamine and the sulfone groups (-SO) of PES nanofibers 2- Hydrogen bonds are formed, and UV curing simultaneously grafts unsaturated monomers (such as NVP and SSS) onto the PES surface. The treatment agent penetrates into the interior of the fiber membrane (approximately 10–20 μm depth), forming a hydrophilic-antibacterial-anticoagulant multifunctional layer that gradually transitions from the inside out, exhibiting good biocompatibility. The micropores (1–2 μm) of the surface functional layer retain the high porosity of the support layer, increasing water flux and optimizing the permeability of the fabricated dialysis membrane. The formation of the UV-cured crosslinked network prevents component dissolution, improves the membrane's mechanical strength, and results in a dialysis membrane with excellent durability.

[0025] Furthermore, sulfonated chitosan is prepared by the following process:

[0026] Citric acid was dissolved in deionized water, chitosan was added and mixed, the temperature was raised to 58-62℃ and the reaction was carried out for 150-200 min; water was added to adjust the pH of the system to neutral, acetone was used for precipitation, and ethanol was used for washing to obtain citric acid-chitosan.

[0027] Citric acid-chitosan and glycidyl ether were mixed and reacted at 48–53 °C for 8–12 h. The mixture was cooled to room temperature and ice water was added to terminate the reaction. Acetone was added to precipitate the mixture, which was then filtered and washed. The mixture was redissolved in acetic acid solution, dialyzed, and dried under vacuum to obtain hydroxypropyl chitosan.

[0028] Hydroxypropyl chitosan and DMF / NMP mixed solvent were mixed at 0–5℃, and sulfonation reagent was added. The mixture was reacted at 25–40℃ for 30–180 min. Residual chlorosulfonic acid was quenched with 5% NaHCO3 solution, and the pH was adjusted to 3. The mixture was then dialyzed and vacuum dried to obtain sulfonated chitosan.

[0029] Furthermore, the mass ratio of chitosan to citric acid is 1:(1.2-1.3).

[0030] The ratio of citric acid to deionized water is 10–15 g / 100 mL;

[0031] Chitosan was added in solution at a concentration of 2 wt%; the solvent was a 1 wt% acetic acid solution.

[0032] Furthermore, the mass ratio of citric acid-chitosan to glycidol is 10:(4-6).

[0033] 0.1% triethylamine can be added to the system as a catalyst.

[0034] Furthermore, the sulfonating agent is a mixture of chlorosulfonic acid and pyridine in a molar ratio of 1:1;

[0035] The mass ratio of hydroxypropyl chitosan to sulfonating agent is 10:(1.5-2.3).

[0036] The ratio of hydroxypropyl chitosan to DMF / NMP mixed solvent is 10–15 g / 100 mL;

[0037] In the DMF / NMP mixed solvent, the volume ratio of DMF (N,N-dimethylformamide) to NMP (N-methylpyrrolidone) is 1:1.

[0038] In the above technical solution, the carboxyl group in citric acid undergoes an amidation reaction with the amino group in chitosan, retaining both the carboxyl and hydroxyl groups to form a polycarboxylated chitosan, which is denoted as citric acid-chitosan. The epoxy group in glycidyl alcohol undergoes ring-opening and reacts with the hydroxyl (or amino) active groups in the prepared citric acid-chitosan, introducing a hydrophilic hydroxypropyl side chain, which is denoted as hydroxypropyl chitosan. Triethylamine acts as a catalyst in the reaction, promoting the ring-opening of the epoxy group and inhibiting side reactions. The prepared hydroxypropyl chitosan is mixed with a sulfonating agent, and chlorosulfonic acid (HClSO3) and pyridine form a mild sulfonation system, attacking the hydroxyl groups (-OH) in the hydroxypropyl chitosan to generate sulfonic acid groups (-SO3H), thus obtaining sulfonated chitosan.

[0039] The sulfonic acid groups (-SO3H) in sulfonated chitosan provide a negative charge, mimicking the structure of heparin. This negative charge repels platelets and plasma proteins, thereby inhibiting the activation of coagulation factors and improving the anticoagulant effect of the dialysis membrane. Residual amino groups (-NH4+) 3+ Through electrostatic adsorption, it interacts with bacterial cell membranes, disrupting their integrity and achieving antibacterial properties of the dialysis membrane. Simultaneously, the sulfonic acid and hydroxyl groups are hydrophilic, synergistically enhancing the hydrophilicity of the functional layer surface, reducing protein adsorption, and inhibiting bacterial adhesion and biofilm formation.

[0040] Furthermore, the cerium phenanthroline triacrylate hybrid CeO2 (Ce-TAP@CeO2) is prepared by the following process:

[0041] Acrylic acid was dissolved in dimethyl sulfoxide, and nano-cerium oxide and 1,10-phenanthroline were added sequentially. The mixture was heated to 50-60°C and reacted for 1-2 hours. The mixture was then filtered under reduced pressure, washed 2-3 times with ethanol, recrystallized with acetone / ethyl ether, and dried under vacuum at 40-50°C for 6-12 hours to obtain cerium-hybridized phenanthroline triacrylate CeO2.

[0042] Furthermore, the mass ratio of nano-cerium oxide (CeO2), acrylic acid, and 1,10-phenanthroline is 1:(0.35–0.45):(0.5–0.7).

[0043] The particle size of nano-cerium oxide is 20–50 nm.

[0044] Furthermore, the amount of dimethyl sulfoxide (DMSO) used is 14.3 to 16.7 times the mass of acrylic acid.

[0045] Furthermore, the acrylic acid contains 0.05 wt% of the polymerization inhibitor 4-methoxyphenol, and the reaction is carried out under nitrogen protection;

[0046] Pretreatment before adding nano-cerium oxide: ultrasonic dispersion at 300W power for 30 minutes to avoid agglomeration.

[0047] In the above technical solution, the nitrogen atom of 1,10-phenanthroline (Phen) reacts with the CeO2 surface Ce... 3+ / Ce 4+ Coordination, and simultaneously the carboxyl group (-COOH) of acrylic acid with Ce 3+ A chelating bond is formed, generating a ternary complex, Ce-O-CO-CH=CH2, which is then loaded onto the surface of nano-cerium dioxide to form Ce-TAP@CeO2, denoted as cerium phenanthroline triacrylate hybrid CeO2, exhibiting good adsorption for urea and other substances. The carbon-carbon double bond (C=C) of acrylic acid is retained, providing active sites for subsequent polymerization.

[0048] Compared to acrylic acid-rare earth ion derivatives (such as cerium phenanthroline triacrylate), cerium phenanthroline triacrylate hybrid CeO2 introduces hybrid ions CeO2, and the surface of CeO2 (particle size <50nm) contains oxygen vacancies (Ce... 3+ / Ce 4+ The CeO2 nanoparticles, filled with Phen and acrylic acid, reduce surface defects and enhance stability. Residual oxygen vacancies catalyze the generation of ROS (·OH, H2O2), initiating a redox cycle that inhibits biofilm formation and enhances antibacterial properties; it also neutralizes free radicals and reduces oxidative stress. Simultaneously, the nano-CeO2 dispersed within the polymer network of the functional layer effectively improves membrane strength.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0050] The present invention describes a method for preparing an antibacterial nanofiber hemodialysis membrane. This method uses N-vinylpyrrolidone, sodium p-styrene sulfonate, cerium phenanthroline triacrylate hybrid CeO2, and lauryl methacrylate as unsaturated monomers, compounded with sulfonated chitosan, heparin, and dopamine to prepare a surface treatment agent. This agent is then used to impregnate a polyethersulfone nanofiber membrane, followed by irradiation curing to form a functional layer. The resulting hemodialysis membrane exhibits high anticoagulation and broad-spectrum antibacterial properties, high permeability, low protein adsorption, and long-term stability. Detailed Implementation

[0051] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] In the following specific implementation,

[0053] Support layer: Polyethersulfone nanofiber membrane was prepared by electrospinning technology, with a porosity of 60%, a thickness of 50 μm, and a fiber diameter of 300-400 nm;

[0054] Chitosan: Deacetylation degree 95%, viscosity: 100-200 mPa·s;

[0055] Chitosan was added in solution at a concentration of 2 wt%; the solvent was a 1 wt% acetic acid solution.

[0056] The particle size of nano-cerium oxide is 20-50 nm;

[0057] Before adding nano-cerium oxide, it was ultrasonically dispersed for 30 minutes at a power of 300W;

[0058] Before adding the phenanthroline cerium hybrid CeO2 triacrylate to the treatment agent, it was ultrasonically dispersed for 5 minutes at 300W power.

[0059] Example 1: A method for preparing an antibacterial nanofiber hemodialysis membrane, comprising the following processes:

[0060] Step 1: Dissolve citric acid in deionized water, add chitosan and mix, heat to 58℃ and react for 200 min; add water to adjust the pH of the system to neutral, precipitate with acetone, wash with ethanol to obtain citric acid-chitosan; the mass ratio of chitosan to citric acid is 1:1.2; the ratio of citric acid to deionized water is 10 g / 100 mL.

[0061] Citric acid-chitosan and glycidyl ether were mixed and reacted at 48°C for 12 h; the mixture was cooled to room temperature and ice water was added to terminate the reaction; acetone was added to precipitate the mixture, which was then filtered and washed; the mixture was redissolved in acetic acid solution, dialyzed, and dried under vacuum to obtain hydroxypropyl chitosan; the mass ratio of citric acid-chitosan to glycidyl ether was 10:4; 0.1% triethylamine was added to the system as a catalyst;

[0062] Hydroxypropyl chitosan and a DMF / NMP mixed solvent were mixed at 3°C, and a sulfonating agent was added. The mixture was reacted at 25°C for 180 min. Residual chlorosulfonic acid was quenched with 5% NaHCO3 solution, and the pH was adjusted to 3. The mixture was then dialyzed and vacuum dried to obtain sulfonated chitosan. The sulfonating agent was a mixture of chlorosulfonic acid and pyridine in a molar ratio of 1:1. The mass ratio of hydroxypropyl chitosan to the sulfonating agent was 10:1.5. The ratio of hydroxypropyl chitosan to the DMF / NMP mixed solvent was 10 g / 100 mL. The volume ratio of DMF to NMP in the DMF / NMP mixed solvent was 1:1.

[0063] Step 2: Dissolve acrylic acid in dimethyl sulfoxide, add nano-cerium oxide and 1,10-phenanthroline sequentially, heat to 50°C, and react for 2 hours; filter under reduced pressure, wash twice with ethanol, recrystallize with acetone / ethyl ether, and dry under vacuum at 40°C for 12 hours to obtain cerium phenanthroline triacrylate hybrid CeO2; the mass ratio of nano-cerium oxide, acrylic acid, and 1,10-phenanthroline is 1:0.35:0.5; the amount of dimethyl sulfoxide is 14.3 times the mass of acrylic acid; the acrylic acid contains 0.05 wt% polymerization inhibitor 4-methoxyphenol, and the reaction is carried out under nitrogen protection;

[0064] Step 3: Dissolve sulfonated chitosan in a DMF / phosphate buffer solution and heparin in a phosphate buffer solution. Mix the two solutions under light-protected conditions and stir at 200 rpm for 30 min. Add dopamine (hydrochloride) and stir for 10 min. Under a nitrogen atmosphere, add unsaturated monomers and stir for 120 min. Add photoinitiator and stir for 30 min. Add the DMF / phosphate buffer solution to obtain a 15 wt% surface treatment agent. Then filter through a 0.45 μm filter membrane and adjust the pH. The concentration was 6.5; the surface treatment agent consisted of the following components by weight: 5 parts sulfonated chitosan, 3 parts heparin, 2 parts dopamine, 20 parts unsaturated monomer, and 1 part photoinitiator benzophenone; the unsaturated monomer consisted of the following components by weight: 8 parts N-vinylpyrrolidone, 4 parts sodium p-styrene sulfonate, 1 part cerium phenanthroline triacrylate hybrid CeO2, and 2.4 parts lauryl methacrylate; the volume ratio of DMF to phosphate buffer (PBS, pH 7.4) was 6:4; the amount of DMF / phosphate buffer mixture added in both additions was the same;

[0065] Step 4: Use a polyethersulfone nanofiber membrane as a support layer, impregnate it with a surface treatment agent. The impregnation ratio of polyethersulfone nanofiber membrane to surface treatment agent is 1g:10mL; the impregnation time is 5min; the extrusion roller pressure is 0.1MPa; UV irradiation is performed. The UV irradiation process conditions are: under nitrogen atmosphere protection, wavelength 365nm, light intensity 8mW / cm², irradiation for 5min; then wavelength 365nm, light intensity 15mW / cm². 2 Irradiate for 12 minutes to form a functional layer and obtain a dialysis membrane.

[0066] Example 2: A method for preparing an antibacterial nanofiber hemodialysis membrane, comprising the following processes:

[0067] Step 1: Dissolve citric acid in deionized water, add chitosan and mix, heat to 60℃ and react for 180 min; add water to adjust the pH of the system to neutral, precipitate with acetone, wash with ethanol to obtain citric acid-chitosan; the mass ratio of chitosan to citric acid is 1:1.25; the ratio of citric acid to deionized water is 12 g / 100 mL.

[0068] Citric acid-chitosan and glycidyl ether were mixed and reacted at 50°C for 10 h; the mixture was cooled to room temperature and ice water was added to terminate the reaction; acetone was added to precipitate the mixture, which was then filtered and washed; the mixture was redissolved in acetic acid solution, dialyzed, and dried under vacuum to obtain hydroxypropyl chitosan; the mass ratio of citric acid-chitosan to glycidyl ether was 10:5; 0.1% triethylamine was added to the system as a catalyst;

[0069] Hydroxypropyl chitosan and a DMF / NMP mixed solvent were mixed at 3°C, and a sulfonating agent was added. The mixture was reacted at 32°C for 90 min. Residual chlorosulfonic acid was quenched with 5% NaHCO3 solution, and the pH was adjusted to 3. The mixture was dialyzed and vacuum dried to obtain sulfonated chitosan. The sulfonating agent was a mixture of chlorosulfonic acid and pyridine in a molar ratio of 1:1. The mass ratio of hydroxypropyl chitosan to the sulfonating agent was 10:1.9. The ratio of hydroxypropyl chitosan to formamide was 12 g / 100 mL. The volume ratio of DMF to NMP in the DMF / NMP mixed solvent was 1:1.

[0070] Step 2: Dissolve acrylic acid in dimethyl sulfoxide, add nano-cerium oxide and 1,10-phenanthroline sequentially, heat to 55℃, and react for 1.5 h; filter under reduced pressure, wash three times with ethanol, recrystallize with acetone / ethyl ether, and dry under vacuum at 45℃ for 9 h to obtain cerium phenanthroline triacrylate hybrid CeO2; the mass ratio of nano-cerium oxide, acrylic acid, and 1,10-phenanthroline is 1:0.40:0.6; the amount of dimethyl sulfoxide is 15.5 times the mass of acrylic acid; the acrylic acid contains 0.05 wt% polymerization inhibitor 4-methoxyphenol, and the reaction is carried out under nitrogen protection;

[0071] Step 3: Dissolve sulfonated chitosan in a DMF / phosphate buffer mixture and heparin in a phosphate buffer mixture. Mix the two under light-protected conditions and stir at 200 rpm for 30 min. Add dopamine (hydrochloride) and stir for 10 min. Under a nitrogen atmosphere, add unsaturated monomers and stir for 120 min. Add photoinitiator and stir for 30 min. Add DMF / phosphate buffer mixture to obtain a surface treatment agent with a concentration of 18 wt%. Then filter through a 0.45 μm filter membrane and adjust the pH to 7. 0; The surface treatment agent comprises the following components by weight: 6.5 parts sulfonated chitosan, 4.5 parts heparin, 2.5 parts dopamine, 30 parts unsaturated monomer, and 1.5 parts photoinitiator benzophenone; The unsaturated monomer comprises the following components by weight: 9 parts N-vinylpyrrolidone, 5 parts sodium p-styrene sulfonate, 1.5 parts cerium phenanthroline triacrylate hybrid CeO2, and 2.7 parts lauryl methacrylate; DMF / phosphate buffer (PBS, pH 7.4) = 6:4; The amounts of DMF / phosphate buffer mixture added in both additions are the same;

[0072] Step 4: Use a polyethersulfone nanofiber membrane as the support layer, impregnate it with a surface treatment agent. The impregnation ratio of polyethersulfone nanofiber membrane to surface treatment agent is 1g:12mL; the impregnation time is 8min; the extrusion roller pressure is 0.2MPa; UV irradiation is performed. The UV irradiation process conditions are: under nitrogen atmosphere protection, wavelength 365nm, light intensity 9mW / cm², irradiation for 8min; then wavelength 365nm, light intensity 18mW / cm². 2 Irradiate for 18 minutes to form a functional layer and obtain a dialysis membrane.

[0073] Example 3: A method for preparing an antibacterial nanofiber hemodialysis membrane, comprising the following processes:

[0074] Step 1: Dissolve citric acid in deionized water, add chitosan and mix, heat to 62℃ and react for 150 min; add water to adjust the pH of the system to neutral, precipitate with acetone, wash with ethanol to obtain citric acid-chitosan; the mass ratio of chitosan to citric acid is 1:1.3; the ratio of citric acid to deionized water is 15 g / 100 mL.

[0075] Citric acid-chitosan and glycidyl ether were mixed and reacted at 53°C for 8 hours. The mixture was cooled to room temperature and ice water was added to terminate the reaction. Acetone was added to precipitate the mixture, which was then filtered and washed. The mixture was redissolved in acetic acid solution, dialyzed, and dried under vacuum to obtain hydroxypropyl chitosan. The mass ratio of citric acid-chitosan to glycidyl ether was 10:6. 0.1% triethylamine was added to the system as a catalyst.

[0076] Hydroxypropyl chitosan and a DMF / NMP mixed solvent were mixed at 3°C, and a sulfonating agent was added. The mixture was reacted at 40°C for 30 min. Residual chlorosulfonic acid was quenched with 5% NaHCO3 solution, and the pH was adjusted to 3. The mixture was dialyzed and vacuum dried to obtain sulfonated chitosan. The sulfonating agent was a mixture of chlorosulfonic acid and pyridine in a molar ratio of 1:1. The mass ratio of hydroxypropyl chitosan to the sulfonating agent was 10:2.3. The ratio of hydroxypropyl chitosan to formamide was 15 g / 100 mL. The volume ratio of DMF to NMP in the DMF / NMP mixed solvent was 1:1.

[0077] Step 2: Dissolve acrylic acid in dimethyl sulfoxide, add nano-cerium oxide and 1,10-phenanthroline sequentially, heat to 60℃, and react for 1 h; filter under reduced pressure, wash three times with ethanol, recrystallize with acetone / ethyl ether, and dry under vacuum at 50℃ for 6 h to obtain cerium phenanthroline triacrylate hybrid CeO2; the mass ratio of nano-cerium oxide, acrylic acid, and 1,10-phenanthroline is 1:0.45:0.7; the amount of dimethyl sulfoxide is 16.7 times the mass of acrylic acid; the acrylic acid contains 0.05 wt% polymerization inhibitor 4-methoxyphenol, and the reaction is carried out under nitrogen protection;

[0078] Step 3: Dissolve sulfonated chitosan in a DMF / phosphate buffer mixture, and heparin in a phosphate buffer mixture. Mix the two under light-protected conditions and stir at 200 rpm for 30 min. Add dopamine (hydrochloride) and stir for 10 min. Under a nitrogen atmosphere, add unsaturated monomers and stir for 120 min. Add photoinitiator and stir for 30 min. Add DMF / phosphate buffer mixture to obtain a 20 wt% surface treatment agent. Then filter through a 0.45 μm filter membrane and adjust the pH. H is 7.5; the surface treatment agent includes the following components by weight: 8 parts sulfonated chitosan, 5 parts heparin, 3 parts dopamine, 40 parts unsaturated monomer, and 2 parts photoinitiator benzophenone; the unsaturated monomer includes the following components by weight: 10 parts N-vinylpyrrolidone, 6 parts sodium p-styrene sulfonate, 2 parts cerium phenanthroline triacrylate hybrid CeO2, and 3.0 parts lauryl methacrylate; DMF / phosphate buffer (PBS, pH 7.4) = 6:4; the amount of DMF / phosphate buffer mixture added in both additions is the same;

[0079] Step 4: Use a polyethersulfone nanofiber membrane as a support layer, impregnate it with a surface treatment agent. The impregnation ratio of polyethersulfone nanofiber membrane to surface treatment agent is 1g:15mL; the impregnation time is 10min; the extrusion roller pressure is 0.3MPa; UV irradiation is performed under the following conditions: under nitrogen atmosphere protection, wavelength 365nm, light intensity 10mW / cm², irradiation for 10min; then wavelength 365nm, light intensity 20mW / cm². 2 Irradiate for 20 minutes to form a functional layer and obtain a dialysis membrane.

[0080] Comparative Example 1: A method for preparing an antibacterial nanofiber hemodialysis membrane, comprising the following processes:

[0081] Step 1: At 3℃, chitosan and DMF / NMP mixed solvent were mixed, and sulfonating agent was added. The mixture was reacted at 25℃ for 180 min. 5% NaHCO3 solution was added to quench residual chlorosulfonic acid, and the pH was adjusted to 3. The mixture was dialyzed and vacuum dried to obtain sulfonated chitosan. The sulfonating agent was a mixture of chlorosulfonic acid and pyridine in a molar ratio of 1:1. The mass ratio of chitosan to sulfonating agent was 10:1.5. The ratio of hydroxypropyl chitosan to formamide was 10 g / 100 mL. The volume ratio of DMF / NMP in the DMF / NMP mixed solvent was 1:1.

[0082] Steps 2-4 are the same as in Example 1, resulting in a dialysis membrane. The surface treatment agent comprises the following components by weight: 5 parts sulfonated chitosan, 3 parts heparin, 2 parts dopamine, 20 parts unsaturated monomer, and 1 part photoinitiator benzophenone. The unsaturated monomer comprises the following components by weight: 8 parts N-vinylpyrrolidone, 4 parts sodium p-styrene sulfonate, 1 part cerium phenanthroline triacrylate hybrid CeO2, and 2.4 parts lauryl methacrylate.

[0083] Comparative Example 2: A method for preparing an antibacterial nanofiber hemodialysis membrane, comprising the following processes:

[0084] Steps 1-3 are the same as steps 2-4 in Example 1, resulting in a dialysis membrane. The surface treatment agent includes the following components by mass: 5 parts chitosan, 3 parts heparin, 2 parts dopamine, 20 parts unsaturated monomer, and 1 part photoinitiator benzophenone. The unsaturated monomer includes the following components by mass: 8 parts N-vinylpyrrolidone, 4 parts sodium p-styrene sulfonate, 1 part cerium phenanthroline triacrylate hybrid CeO2, and 2.4 parts lauryl methacrylate.

[0085] Comparative Example 3: A method for preparing an antibacterial nanofiber hemodialysis membrane, comprising the following processes:

[0086] Step 1: Dissolve acrylic acid in 95% ethanol, then add lanthanum salt and 1,10-phenanthroline sequentially. Heat to 60°C and react for 4 hours. Filter under reduced pressure, wash twice with ethanol, recrystallize in acetone / ether, and dry under vacuum at 40°C for 12 hours to obtain lanthanum phenanthroline triacrylate. The mass ratio of lanthanum salt, acrylic acid, and 1,10-phenanthroline is 1:3:1. Lanthanum salt is added in the form of lanthanum nitrate solution with a concentration of 3.0 wt%. The amount of solvent used is 22 times the mass of acrylic acid. The acrylic acid contains 0.1 wt% hydroquinone as a polymerization inhibitor. The reaction is carried out under nitrogen protection.

[0087] Step 2: Dissolve chitosan in a DMF / phosphate buffer solution and heparin in phosphate buffer solution. Mix the two solutions under light-protected conditions and stir at 200 rpm for 30 min. Add dopamine (hydrochloride) and stir for 10 min. Under a nitrogen atmosphere, add unsaturated monomers and stir for 120 min. Add photoinitiator and stir for 30 min. Add the DMF / phosphate buffer solution to obtain a 15 wt% surface treatment agent. Then filter through a 0.45 μm filter membrane. The pH was adjusted to 6.5. The surface treatment agent consisted of the following components by weight: 5 parts chitosan, 3 parts heparin, 2 parts dopamine, 20 parts unsaturated monomers, and 1 part photoinitiator benzophenone. The unsaturated monomers consisted of the following components by weight: 8 parts N-vinylpyrrolidone, 4 parts sodium p-styrene sulfonate, 1 part lanthanum phenanthroline triacrylate, and 2.4 parts lauryl methacrylate. The DMF / phosphate buffer (PBS, pH 7.4) ratio was 6:4. The amounts of DMF / phosphate buffer mixture added in both additions were the same.

[0088] Step 3 is the same as step 4 in Example 1, and a dialysis membrane is obtained.

[0089] Comparative Example 4: A method for preparing an antibacterial nanofiber hemodialysis membrane, comprising the following processes:

[0090] Step 1: Dissolve chitosan in DMF / phosphate buffer and heparin in phosphate buffer. Mix the two solutions under light-protected conditions and stir at 200 rpm for 30 min. Add dopamine (hydrochloride) and stir for 10 min. Under nitrogen atmosphere, add unsaturated monomer and stir for 120 min. Add photoinitiator and stir for 30 min. Add DMF / phosphate buffer to obtain a 15 wt% surface treatment agent. Then filter through a 0.45 μm filter membrane and adjust the pH to 6.5. The surface treatment agent consists of the following components by weight: 5 parts chitosan, 3 parts heparin, 2 parts dopamine, 20 parts unsaturated monomer, and 1 part benzophenone photoinitiator. The unsaturated monomer consists of the following components by weight: 8 parts N-vinylpyrrolidone, 4 parts sodium p-styrene sulfonate, and 2.4 parts lauryl methacrylate. The ratio of DMF / phosphate buffer (PBS, pH 7.4) is 6:4. The amount of DMF / phosphate buffer added in both steps is the same.

[0091] Step 2 is the same as step 4 in Example 1, and a dialysis membrane is obtained.

[0092] Experiment: Dialysis membranes obtained in Examples 1-3 and Comparative Examples 1-4 were used to prepare samples. Their performance was tested and the results were recorded.

[0093] Mechanical property testing: The tensile strength of the specimen was tested with reference to GB / T 1040.3 at a rate of 10 mm / min. Before the test, the specimen was equilibrated at 25℃ and 50% humidity for 24 hours.

[0094] Anticoagulation performance test: The clotting time (APTT) of the sample was tested with reference to GB / T 16886.4.

[0095] Antibacterial performance test: Using GB / T 20944.3 (shaking method) as the reference standard, the inhibition rate of the sample against *Escherichia coli* and *Staphylococcus aureus* was tested, with a bacterial concentration OD600 = 0.1 (~10). 8 (CFU / mL); and the membrane was soaked in sterile PBS as a negative control to verify the absence of false positives in antibacterial activity;

[0096] Using ASTM E2180-07 as a reference standard, the biofilm coverage of the samples was tested, and the bacterial species was Pseudomonas aeruginosa.

[0097] Albumin adsorption capacity test: Bovine serum albumin (BSA) was dissolved in phosphate buffer (PBS, 0.01M, pH=7.4) to prepare a 1.0 mg / mL BSA solution; the sample was placed in this BSA solution and incubated in a 37℃ constant temperature shaker at 60-80 rpm for 2 h; the supernatant was collected to detect the BSA concentration, and the albumin adsorption capacity (μg / cm³) was calculated. 2 );

[0098] Water flux test: Cut an effective area of ​​10cm² 2 A circular membrane sample was placed in a dialysis cell and sealed. After equilibration for 10 minutes, the volume of permeate was collected over 30 minutes, and the water flux (J) was calculated. In the experiment, the transmembrane pressure was 100 mmHg (13.3 kPa), the temperature was 37 ± 0.5 ℃, and the test solution was ultrapure water.

[0099] β2-microglobulin (β2-MG) clearance test: The β2-microglobulin clearance rate of the samples was detected using a simulated dialysis system. The blood chamber contained PBS (pH 7.4) with β2-MG (100 mg / L), and the dialysate chamber contained pure PBS (pH 7.4). The blood flow rate was 200 mL / min, and the dialysate flow rate was 500 mL / min. The experimental temperature was 37℃, and the test was conducted for 4 hours. The β2-MG concentration was determined by ELISA, and the clearance rate was calculated.

[0100] Long-term stability test: The performance degradation rate (%) was measured after simulating dialysis 100 times on the sample.

[0101] Table 1. Test data for mechanical properties, anticoagulant properties, and antibacterial properties.

[0102]

[0103] Table 2. Experimental data on adsorption properties and long-term stability.

[0104]

[0105] Based on the data in the table above, the following conclusions can be clearly drawn:

[0106] The dialysis membranes obtained in Examples 1-3 were compared with those obtained in Comparative Examples 1-4. The test results show that...

[0107] Compared with the comparative examples, the dialysis membranes obtained in Examples 1-3 exhibit superior tensile strength, clotting time, and antibacterial effect. Furthermore, their anti-protein adsorption, water flux, β2-MG clearance rate, and long-term stability remain excellent. This fully demonstrates that the present invention improves the antibacterial performance of dialysis membranes and synergistically enhances mechanical properties, anticoagulation, permeability, low protein adsorption, and long-term stability.

[0108] Compared with Example 1, the preparation process of sulfonated chitosan in the surface treatment agent in Comparative Example 1 was different; in Comparative Example 2, sulfonated chitosan was replaced with chitosan; in Comparative Example 3, sulfonated chitosan in the surface treatment agent was replaced with chitosan, and cerium phenanthroline hybrid CeO2 in the unsaturated monomer was replaced with lanthanum phenanthroline triacrylate; in Comparative Example 4, sulfonated chitosan in the surface treatment agent was replaced with chitosan, and cerium phenanthroline hybrid CeO2 was not added. The performance of the dialysis membranes obtained in Comparative Examples 1-4 deteriorated, indicating that the preparation process and the components used in the dialysis membrane of the present invention can comprehensively improve the high-efficiency anticoagulation performance, high permeability, low protein adsorption, and long-term stability while endowing it with broad-spectrum antibacterial properties.

[0109] Comparative Example 2 serves as a control with Comparative Examples 3 and 4, and can be used to verify the effects of different acrylic acid-rare earth derivatives, such as cerium phenanthroline triacrylate hybrid CeO2 and lanthanum phenanthroline triacrylate, on the performance of hemodialysis membranes. The chitosan in Comparative Example 2 lacks sulfonation modification, resulting in severely insufficient hydrophilicity, anticoagulant properties, and antiprotein adsorption capacity. Chitosan itself also exhibits weak antibacterial properties. This makes its performance significantly inferior to the examples, manifesting as easy contamination, rapid decline in flux and clearance rate, and poor antibacterial activity. The lanthanum phenanthroline triacrylate introduced in Comparative Example 3 provides some antibacterial activity and a small amount of hydrophilic groups, but its effect is far less than that of cerium phenanthroline triacrylate hybrid CeO2.

[0110] As shown above, the tensile strength, anticoagulation performance, antibacterial performance, and solute removal (β2-MG) of the dialysis membrane are significantly improved due to the synergistic enhancement of sulfonated chitosan and Ce-TAP@CeO2. Hydroxypropyl modification enhances interfacial bonding, contributing to improved mechanical strength. In samples without sulfonation or without CeO2 (Comparative Example 1 / 4), insufficient charge density hinders β2-MG adsorption, reduces solute transfer efficiency, and significantly decreases anticoagulation and antibacterial properties. Carboxymethyl chitosan (Comparative Example 3) exhibits reduced β2-MG removal due to insufficient negative charge density. The introduction of functional layers leads to a decrease in water flux, but in Examples 1-3, the decrease is controllable due to the hydrophilic modification and ordered pore structure of sulfonated chitosan. In the comparative examples, poor interfacial bonding or pore blockage (such as with unsulfonated chitosan) results in a significant decrease in flux.

[0111] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing an antibacterial nanofiber hemodialysis membrane, characterized in that: Including the following processes: Chitosan derivatives, heparin, dopamine, unsaturated monomers, and initiators are mixed in a DMF / phosphate buffer solution to obtain a surface treatment agent. A nanofiber membrane is used as a support layer, impregnated with a surface treatment agent, and then irradiated with UV light to form a functional layer, thus obtaining a dialysis membrane. The unsaturated monomer comprises the following components by mass: 8-10 parts N-vinylpyrrolidone, 4-6 parts sodium p-styrene sulfonate, 1-2 parts cerium phenanthroline triacrylate hybrid CeO2, and 2.4-3.0 parts lauryl methacrylate; The chitosan derivative is sulfonated chitosan, which is prepared by the following process: Hydroxypropyl chitosan and DMF / NMP mixed solvent were mixed at 0–5℃, and a sulfonating agent was added. The mixture was reacted at 25–40℃ for 30–180 min to obtain sulfonated chitosan. The triacrylate phenanthroline cerium hybrid CeO2 is prepared by the following process: Acrylic acid was dissolved in dimethyl sulfoxide, and nano-cerium oxide and 1,10-phenanthroline were added sequentially. The mixture was heated to 50-60°C and reacted for 1-2 hours to obtain cerium-hybridized phenanthroline triacrylate CeO2.

2. The method for preparing an antibacterial nanofiber hemodialysis membrane according to claim 1, characterized in that: The hydroxypropyl chitosan is prepared by the following process: Citric acid was dissolved in deionized water, chitosan was added and mixed, the temperature was raised to 58-62℃ and the reaction was carried out for 150-200 min to obtain citric acid-chitosan. Citric acid-chitosan and glycidol were mixed and reacted at 48-53℃ for 8-12 hours to obtain hydroxypropyl chitosan.

3. The method for preparing an antibacterial nanofiber hemodialysis membrane according to claim 1, characterized in that: The mass ratio of hydroxypropyl chitosan to sulfonating agent is 10: (1.5 to 2.3).

4. The method for preparing an antibacterial nanofiber hemodialysis membrane according to claim 2, characterized in that: The mass ratio of chitosan to citric acid is 1: (1.2 to 1.3).

5. The method for preparing an antibacterial nanofiber hemodialysis membrane according to claim 2, characterized in that: The mass ratio of citric acid, chitosan, and glycidyl is 10:(4-6).

6. The method for preparing an antibacterial nanofiber hemodialysis membrane according to claim 1, characterized in that: The process conditions for UV irradiation are: wavelength 365nm, light intensity 5-8mW / cm². 2 Irradiate for 5–10 minutes; then at a wavelength of 365 nm and a light intensity of 12–18 mW / cm². 2 Irradiate for 12–20 minutes.

7. The method for preparing an antibacterial nanofiber hemodialysis membrane according to claim 1, characterized in that: The mass ratio of nano-cerium oxide, acrylic acid, and 1,10-phenanthroline is 1:(0.35-0.45):(0.5-0.7).

8. An antibacterial nanofiber hemodialysis membrane prepared by the preparation method according to any one of claims 1-7.

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