A composite heparin anticoagulant coating and its preparation method

Abstract

The present invention relates to the field of medical devices, and in particular to a composite heparin anticoagulant coating and a preparation method thereof. The method comprises ultraviolet light pretreatment: performing ultraviolet light pretreatment on a substrate material to induce polyethyleneimine to be grafted onto the surface of the material; directional coating: coating the surface of the substrate material with a heparin solution and fixing it with an EDC solution; and changing the coating direction midway through the coating process. The present invention introduces amino chains onto the surface of the substrate material through ultraviolet light, resulting in a positive charge on the surface, which is then combined with ionic bonds to form a heparin coating. After coating, the coating is fixed with an EDC solution, and the coating direction is changed midway through the coating process, thereby improving the stability, uniformity, hydrophilicity, and anticoagulant properties of the coating.

Description

Technical Field

[0001] The present invention relates to the field of medical devices, and in particular to a composite heparin anticoagulant coating and a preparation method thereof. Background Art

[0002] Blood-contacting medical devices often suffer from poor biocompatibility and hemocompatibility, leading to adsorption of plasma proteins on the material surface upon contact with blood, which can lead to coagulation and even thrombosis. Therefore, surface modification of polymer biomaterials used in medical devices that come into contact with human blood, and the introduction of anticoagulants to reduce platelet adhesion and prevent thrombosis, is crucial.

[0003] Polymer biomaterials used in blood-contact medical devices include polyethylene (PE), polypropylene (PP), polycarbonate (PC), poly(4-methylpentene-1) (PMP), and polyvinyl chloride (PVC). Common surface modification strategies include creating inert membrane surfaces, introducing bioactive substances, and surface biomimetic modification. However, currently, physical modification methods are often used for substrate materials, introducing active substances through coating to modify the surface, which results in poor stability and easy shedding.

[0004] Ultraviolet light grafting is the process of generating active free radicals on the surface of the grafted material under ultraviolet light irradiation, which in turn triggers the material to undergo chain growth reaction to generate grafted chains, thereby improving the hydrophilicity and biocompatibility of the material.

[0005] Heparin is a naturally occurring linear polysaccharide composed of alternating components of glucosamine, L-iduronide, N-acetylglucosamine, and D-glucuronic acid. It is primarily located within mast cell granules, providing natural anticoagulant surface activity to vascular endothelial cells. Upon contact with blood, it interacts with antithrombin III (AT III) to prevent thrombosis. Clinically, it is widely used for the prevention and treatment of thromboembolic diseases, early treatment of disseminated intravascular coagulation, and in vitro anticoagulation. Currently, heparin coating technologies fall into two main categories: physical coating and chemical covalent grafting. However, existing coating technologies suffer from poor uniformity and stability, and are susceptible to elution over time.

[0006] CN115990297 A discloses a heparin anticoagulant coating based on PTFE material and a method for preparing the heparin anticoagulant coating. The PTFE material is first treated with oxygen plasma, dopamine and APTMS are coated on the surface of the activated PTFE by dip coating to introduce active amino groups, and then a dense acrylic acid homopolymer (pHPA) is fixed. The PTFE material coated with the pHPA coating is then immersed in a heparin solution containing active carboxyl groups, incubated, and heparin grafted to obtain the heparin coating. The preparation process is relatively complicated, and the dip coating results in a low utilization rate.

[0007] CN111544646 A discloses a small-caliber artificial blood vessel with a heparin coating grafted onto its surface and a method for preparing the small-caliber artificial blood vessel. The method involves soaking a substrate surface in a dopamine solution for reaction, coating it with multiple layers of polydopamine, then grafting it with polyethyleneimine via chemical bonds. Finally, heparin is activated using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS), and the heparinized surface is obtained through amide bond bonding. Since the dopamine is physically coated on the substrate surface, the heparin coating easily falls off along with the dopamine coating. Summary of the Invention

[0008] In order to solve the above technical problems, the present invention provides a composite heparin anticoagulant coating and a preparation method thereof.

[0009] Currently, anticoagulant coatings used on medical devices often utilize physical blending and ion adsorption to coat surfactants on their surfaces, resulting in poor coating stability and uniformity. Furthermore, the coating process is often static immersion or unidirectional. Therefore, this paper proposes a method for preparing a heparin coating using UV light pretreatment followed by directional coating, improving the coating's stability, uniformity, hydrophilicity, and anticoagulant properties.

[0010] Specifically, the method for preparing the composite heparin anticoagulant coating provided in the first aspect of the present invention comprises:

[0011] 1) UV pretreatment: The substrate material is pretreated with UV light to initiate polyethyleneimine (PEI) grafting onto the surface of the material.

[0012] 2) Directional coating: A heparin solution is applied to the surface of the substrate material and fixed with an EDC solution; the coating direction is changed midway. This method uses ultraviolet light to introduce amino chains onto the surface of the substrate material, imparting a positive charge to the surface. Heparin then ionically bonds with the amino chains to form a heparin coating. However, this ionically bonded heparin coating cannot be preserved for long periods of time due to hydrophilic protein binding and blood flow. After coating, the coating is fixed with an EDC solution to enhance stability, and the coating direction is changed midway, improving the coating's stability, uniformity, hydrophilicity, and anticoagulant properties.

[0013] The present invention realizes uniform coating of the heparin coating and enhances the stability of the coating by using the heparin solution and the EDC solution to cyclically flush the base material and change the direction.

[0014] Preferably, the heparin solution is circulated at room temperature for 1-4 hours, and the circulatory direction is changed and the circulatory direction is continued for 1-4 hours. For example, the circulatory time and the circulatory time after changing the circulatory direction can be 1 hour, 1.5 hours, 1.8 hours, 2 hours, 2.2 hours, 2.5 hours, 3 hours, 3.5 hours, 3.8 hours, 4 hours, etc., and any value and range therebetween.

[0015] More preferably, the EDC solution is circulated and flushed at room temperature for 0.5-2 h, and the circulation direction is changed and then the circulation is continued for 0.5-2 h.

[0016] More preferably, the flow rate of the heparin solution and / or EDC solution for circulatory flushing is 0.05-0.5 LPM, for example, the flow rate is 0.08 LPM, 0.09 LPM, 0.1 LPM, 0.2 LPM, 0.3 LPM, 0.4 LPM, etc., and any values and ranges therebetween.

[0017] The flow rate within the preferred range enables the heparin and EDC solutions to fully contact the surface of the substrate material, ensuring their uniform coating and reaction.

[0018] More preferably, the solvent of the heparin solution and / or the EDC solution is disodium hydrogen phosphate-citric acid buffer solution.

[0019] More preferably, the mass fraction of the heparin solution is 0.05%-0.3%, and the pH is 2-5. For example, the mass fraction is 0.05%, 0.06%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.28%, 0.3%, etc., and any values and ranges therebetween.

[0020] Further preferably, the mass fraction of the EDC solution is 0.002‰-0.03‰ and the pH is 2-6. For example, the mass fraction is 0.002‰, 0.003‰, 0.004‰, 0.005‰, 0.006‰, 0.008‰, 0.009‰, 0.01‰, 0.015‰, 0.02‰, 0.025‰, 0.028‰, 0.03‰, etc., and any values and ranges therebetween. A heparin solution with a mass fraction of 0.05%-0.3% and a pH of 2-5 is prepared with a sodium hydrogen phosphate-citric acid buffer solution to ensure better heparin function. The EDC solution has a mass fraction of 0.002‰-0.03‰ and a pH of 2-6 and is also prepared with a sodium hydrogen phosphate-citric acid buffer solution to better ensure reaction activity and efficiency.

[0021] Preferably, the ultraviolet light pretreatment in step 1) includes plasma-ultraviolet pretreatment or ultraviolet-ozone pretreatment.

[0022] In the present invention, UV pretreatment involves modifying the surface of the substrate material under UV irradiation, initiating PEI grafting onto the surface of the material, and pre-treating the material to improve its hydrophilicity and bioactivity. Preferably, the substrate material is UV pretreated without a photosensitizer, and free radicals or oxygen-containing groups are generated on the surface of the material through plasma-UV or UV-ozone treatment.

[0023] Preferably, the plasma-UV pretreatment comprises:

[0024] 1) Place the substrate material in an argon plasma environment for treatment.

[0025] 2) Treating the treated substrate material in an environment containing O2.

[0026] 3) Mixing the PEI solution with the substrate material and reacting them under UV irradiation. This method treats the substrate material in an argon plasma environment to generate free radicals on its surface. The treated substrate material is then exposed to air (O2 environment) to form peroxide groups on the surface. This substrate is then placed in the PEI solution. Under UV irradiation, the peroxide groups decompose into free radical initiating substances that are grafted onto the surface to form grafted chains.

[0027] Preferably, in step 1), the PMP hollow fiber membrane is placed in an argon plasma environment for treatment for 10-15 minutes.

[0028] Preferably, in step 2), the treatment is carried out in air for 10-15 minutes.

[0029] Preferably, in step 3), the solvent of the PEI solution is a phosphate buffer solution with a configuration mass fraction of 1%-16%; the reaction is carried out in an ice-water bath at a stirring speed of 35-75 rpm, and the reaction time is 20-30 min.

[0030] Preferably, after step 3), the method further comprises washing with deionized water for 12-24 hours and freeze-drying.

[0031] Preferably, the UV-ozone pretreatment comprises:

[0032] 1) Place the substrate material under a low-pressure mercury vapor lamp for activation.

[0033] 2) Mix the PEI solution with the substrate material and react under UV irradiation.

[0034] In the present invention, the substrate material is placed under a low-pressure mercury vapor lamp, and the surface of the substrate material is activated to generate a series of oxygen-containing groups, which in turn trigger PEI grafting to generate graft chains on the surface.

[0035] Preferably, in step 1), the low-pressure mercury vapor lamp emits ultraviolet light with wavelengths of 253.7 nm and 184.9 nm; and the activation treatment time is 10-20 min.

[0036] Preferably, in step 2), the solvent of the PEI solution is a phosphate buffer solution with a mass fraction of 1%-16%; the reaction is carried out in an ice-water bath at a stirring speed of 35-75 rpm, and the reaction time is 20-30 min.

[0037] Preferably, after step 2), the method further comprises washing with deionized water for 12-24 hours and freeze-drying.

[0038] Preferably, the substrate material is a PMP hollow fiber membrane.

[0039] As a specific embodiment, the plasma-ultraviolet pretreatment comprises the following steps:

[0040] S1. Place the PMP hollow fiber membrane in an argon plasma environment for 10-15 min to generate free radicals on the PMP surface.

[0041] S2. The PMP hollow fiber membrane with free radicals generated on the surface is exposed to air for 10-15 minutes (O2 environment), and peroxide groups are formed on the surface of the hollow fiber membrane.

[0042] S3. Prepare a PEI solution with a mass fraction of 1-16% using phosphate buffered saline (PBS).

[0043] S4. Transfer a PEI solution with a mass fraction of 1%-16% into a three-necked flask, then move the PMP hollow fiber membrane into the three-necked flask, introduce nitrogen into the flask for 15-30 minutes, exhaust all oxygen, turn on the UV lamp, and keep the entire process in an ice-water bath and a dynamic environment (set the stirring speed to 50 rpm) for 20-30 minutes.

[0044] S5. Take out the PMP hollow fiber membrane, wash it with deionized water for 12-24 hours to remove the unreacted substances and the generated copolymers, and finally place it in a freeze drying box for freeze drying.

[0045] As a specific embodiment, the ultraviolet-ozone pretreatment comprises the following steps:

[0046] S1. After the PMP hollow fiber membrane is placed under a low-pressure mercury vapor lamp (which can simultaneously emit ultraviolet light with wavelengths of 253.7 nm and 184.9 nm) for 10-20 minutes, the surface of the PMP hollow fiber membrane is activated and a series of oxygen-containing groups are generated.

[0047] S2. Use PBS to prepare a PEI solution with a mass fraction of 1-16%.

[0048] S3. Transfer the PEI solution with a mass fraction of 1-16% into a three-necked flask, then move the PMP hollow fiber membrane into the three-necked flask, introduce nitrogen into the flask for 15-30 minutes, exhaust all oxygen, turn on the UV lamp, and keep the whole process in an ice-water bath and a dynamic environment (set the stirring speed to 50 rpm) for 20-30 minutes.

[0049] S4. Take out the PMP hollow fiber membrane, wash it with deionized water for 12-24 hours to remove the unreacted substances and the generated copolymers, and finally place it in a freeze drying box for freeze drying.

[0050] The second aspect of the present invention provides a composite heparin anticoagulant coating prepared by the above preparation method.

[0051] A third aspect of the present invention provides the use of the composite heparin anticoagulant coating obtained by the above-mentioned preparation method in blood-contact medical devices.

[0052] The beneficial effects of the present invention are at least:

[0053] (1) The present invention generates free radicals or oxygen-containing groups on the surface of the substrate material by ultraviolet excitation, and then grafts substances onto the surface to modify its hydrophilicity and biocompatibility, thereby improving the stability of the coating.

[0054] (2) The present invention does not require a photosensitizer. Free radicals or oxygen-containing groups are generated on the surface of the substrate material by plasma-ultraviolet or ultraviolet-ozone. The heparin coating prepared by grafting the material and coating it with a heparin solution has a good anticoagulant effect.

[0055] (3) The present invention changes the coating direction during coating, which can achieve coating uniformity, increase heparin coverage, and improve the hydrophilicity and anticoagulant effect of the heparin coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0057] Figure 1 This is a diagram of the plasma-UV pretreatment concept provided by an embodiment of the present invention.

[0058] Figure 2 This is a diagram of the UV-ozone pretreatment process provided by an embodiment of the present invention.

[0059] Figure 3 The water contact angle graphs of the PMP hollow fiber membrane surface before and after UV pretreatment provided in the embodiments of the present invention, wherein (a) is a water contact angle graph of the untreated PMP hollow fiber membrane, (b) is a water contact angle graph of the PMP hollow fiber membrane after plasma-UV pretreatment (Example 1), and (c) is a water contact angle graph of the PMP hollow fiber membrane after UV-ozone pretreatment (Example 2).

[0060] Figure 4 Figures 2A and 2B show the toluidine blue staining verification results provided in the embodiments of the present invention, wherein (a) is a staining picture of an untreated PMP hollow fiber membrane, (b) is a staining picture of a PMP hollow fiber membrane directly coated with heparin, (c) is a staining picture of a PMP hollow fiber membrane (Example 1) that was pretreated with plasma-UV and then coated with heparin, and (d) is a staining picture of a PMP hollow fiber membrane (Example 2) that was pretreated with UV-ozone and then coated with heparin.

[0061] Figure 5 The water contact angle graphs of the heparin coatings provided in the embodiments of the present invention, wherein (a) is a water contact angle graph of the PMP hollow fiber membrane directly coated with heparin, (b) is a water contact angle graph of the PMP hollow fiber membrane after plasma-UV pretreatment and then heparin coating (Example 1), and (c) is a water contact angle graph of the PMP hollow fiber membrane after UV-ozone pretreatment and then heparin coating (Example 2).

[0062] Figure 6 This is a test of the anticoagulant effect of the heparin coating prepared in the examples of the present invention, wherein (a) is a picture of the untreated PMP hollow fiber membrane after being in contact with blood for 6 hours, (b) is a picture of the PMP hollow fiber membrane directly coated with heparin after being in contact with blood for 6 hours, (c) is a picture of the PMP hollow fiber membrane (Example 1) pretreated with plasma-UV and then coated with heparin after being in contact with blood for 6 hours, and (d) is a picture of the PMP hollow fiber membrane (Example 2) pretreated with UV-ozone and then coated with heparin after being in contact with blood for 6 hours.

[0063] Figure 7 These are the staining results of the heparin coating prepared by directional coating in an embodiment of the present invention, wherein (a) is a staining picture of the front and back sides of the PMP hollow fiber membrane after unidirectional coating after pretreatment, and (b) is a staining picture of the front and back sides of the PMP hollow fiber membrane after directional coating after pretreatment.

[0064] Figure 8The figures show the staining results of the heparin coating using cyclic flushing and reverse flushing at different flow rates in this embodiment, where (a) is a staining picture of the PMP hollow fiber membrane using cyclic flushing and reverse flushing at a flow rate of 1 LPM, and (b) is a staining picture of the PMP hollow fiber membrane using cyclic flushing and reverse flushing at a flow rate of 0.3 LPM.

[0065] Figure 9 The figures show the staining results of the heparin-coated membrane after cyclic flushing and reverse flushing at different times in this embodiment, wherein (a) is a staining picture of the PMP hollow fiber membrane after cyclic flushing and reverse flushing for 0.5 h each, and (b) is a staining picture of the PMP hollow fiber membrane after cyclic flushing and reverse flushing for 2 h each.

[0066] Figure 10 The figures show the staining results of the heparin coatings coated with heparin solutions of different concentrations in this example, wherein (a) is a staining picture of the PMP hollow fiber membrane coated with 0.03% heparin solution, and (b) is a staining picture of the PMP hollow fiber membrane coated with 0.3% heparin solution.

[0067] Figure 11 The figures show the staining results of the heparin coating fixed with EDC solutions of different concentrations in this example, where (a) is a staining picture of the PMP hollow fiber membrane fixed with 0.001‰ EDC solution, and (b) is a staining picture of the PMP hollow fiber membrane fixed with 0.03‰ EDC solution. DETAILED DESCRIPTION

[0068] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0069] It should be understood that the following examples are merely illustrative and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope that the present invention is intended to protect. Unless otherwise indicated, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods. Those in which specific techniques or conditions are not specified in the examples are all conventional methods or are carried out according to the techniques or conditions described in the literature in this field, or are carried out according to the product instructions. Those whose manufacturers are not specified for the reagents and instruments used are all conventional products that can be purchased through regular channels.

[0070] The implementation steps of the present invention are as follows, taking PMP hollow fiber membrane as an example:

[0071] Example 1

[0072] This embodiment provides a method for preparing a heparin coating by plasma-ultraviolet pretreatment of a PMP hollow fiber membrane and then directional coating. Figure 1 ), the steps are as follows.

[0073] S1. Place the PMP hollow fiber membrane in an argon plasma environment for 10 min to generate free radicals on the PMP surface.

[0074] S2. The PMP hollow fiber membrane with free radicals generated on the surface was exposed to air for 15 min (O2 environment), and peroxide groups were formed on the surface of the hollow fiber membrane.

[0075] S3. Use PBS to prepare a 10% PEI solution.

[0076] S4. Transfer the 10% PEI solution into a three-necked flask, then move the PMP hollow fiber membrane into the three-necked flask, introduce nitrogen into the flask for 20 minutes to expel all oxygen, turn on the UV lamp, and keep the entire process in an ice-water bath and a dynamic environment (set the stirring speed to 50 rpm) for 25 minutes.

[0077] S5. The PMP hollow fiber membrane was taken out and washed with deionized water for 24 h to remove unreacted substances and generated copolymers, and finally placed in a freeze drying oven for freeze drying.

[0078] S6. Build a coating circuit device.

[0079] S7. Use sodium hydrogen phosphate-citrate buffer solution to prepare a heparin solution with a mass fraction of 0.3% and a pH of 3-4.

[0080] S8. Circulate and flush at a flow rate of 0.3 LPM for 2 hours at room temperature. After changing the circulation direction, continue to circulate and flush for 2 hours.

[0081] S9. Remove the solution from the circuit.

[0082] S10. Prepare an EDC solution with a mass fraction of 0.03‰ and a pH of 5-6 using disodium hydrogen phosphate-citric acid buffer solution.

[0083] S11. Circulate and flush at a flow rate of 0.3 LPM for 0.5 h at room temperature. After changing the circulation direction, continue circulating and flushing for 0.5 h.

[0084] S12. Remove the solution from the circuit.

[0085] S13. Place the coated object in an oven and dry for 8 hours.

[0086] Example 2

[0087] This embodiment provides a method for preparing a heparin coating by UV-ozone pretreatment of a PMP hollow fiber membrane and directional coating. Figure 2 ), the steps are as follows.

[0088] S1. After the PMP hollow fiber membrane was placed under a low-pressure mercury vapor lamp (which can simultaneously emit ultraviolet light with wavelengths of 253.7 nm and 184.9 nm) for 15 minutes, the surface of the PMP hollow fiber membrane was activated and a series of oxygen-containing groups were generated.

[0089] S2. Use PBS to prepare a 10% PEI solution.

[0090] S4. Transfer the 10% PEI solution into a three-necked flask, then move the PMP hollow fiber membrane into the three-necked flask, introduce nitrogen into the flask for 20 minutes to expel all oxygen, turn on the UV lamp, and keep the entire process in an ice-water bath and a dynamic environment (set the stirring speed to 50 rpm) for 25 minutes.

[0091] S5. The PMP hollow fiber membrane was taken out and washed with deionized water for 24 h to remove unreacted substances and generated copolymers, and finally placed in a freeze drying oven for freeze drying.

[0092] S6. Build a coating circuit device.

[0093] S7. Use sodium hydrogen phosphate-citrate buffer solution to prepare a heparin solution with a mass fraction of 0.3% and a pH of 3-4.

[0094] S8. Circulate and flush at a flow rate of 0.3 LPM for 2 hours at room temperature. After changing the circulation direction, continue to circulate and flush for 2 hours.

[0095] S9. Remove the solution from the circuit.

[0096] S10. Prepare an EDC solution with a mass fraction of 0.03‰ and a pH of 5-6 using disodium hydrogen phosphate-citric acid buffer solution.

[0097] S11. Circulate and flush at a flow rate of 0.3 LPM for 0.5 h at room temperature. After changing the circulation direction, continue circulating and flushing for 0.5 h.

[0098] S12. Remove the solution from the circuit.

[0099] S13. Place the coated object in an oven and dry for 8 hours.

[0100] Example 3

[0101] The same treatment method as in Example 1 was used, except that the flow rates of the circulating flushing and the reverse flushing were changed to 1 LPM during the heparin coating.

[0102] Example 4

[0103] The same treatment method as in Example 2 was used, except that the time for the cyclic flushing and reverse flushing was changed to 0.5 h during the heparin coating.

[0104] Example 5

[0105] The same treatment method as in Example 1 was used, except that the heparin solution during coating was 0.03%.

[0106] Example 6

[0107] The same treatment method as in Example 2 was used, except that the concentration of the EDC solution used to fix the coating was 0.001‰.

[0108] Comparative Example 1

[0109] The same treatment method was used as in Example 1 and Example 2, except that the PMP hollow fiber membrane was directly coated with heparin without UV pretreatment.

[0110] Comparative Example 2

[0111] The same treatment method as in Example 1 was used, except that after the PMP hollow fiber membrane was UV pretreated, heparin was only coated in one direction.

[0112] Testing and Characterization

[0113] (1) Hydrophilic properties of PMP hollow fiber membranes before and after UV pretreatment (Examples 1 and 2).

[0114] The results are as follows Figure 3 As shown in the figure, the contact angle of water on the surface of PMP before and after pretreatment was tested at room temperature, which verified that PMP is a hydrophobic material. After pretreatment, the water contact angle decreased from 95.5° to 90.3° (or 89.8°), indicating that the hydrophilicity of PMP was improved after grafting.

[0115] (2) After UV pretreatment and heparin coating, the uniformity and coverage of the heparin coating changed (Examples 1 and 2).

[0116] The heparin coating coverage was tested using the toluidine blue staining method. When the dye was adsorbed onto the negatively charged heparin surface, the color of the dye changed from blue to purple. Figure 4As shown, when heparin coating was performed directly without UV pretreatment (Comparative Example 1), the staining result was not obvious, showing a light blue-purple color, indicating that only a small amount of heparin coating adhered to the surface of the PMP hollow fiber and the coating effect was poor. However, after UV pretreatment and coating, the surface of the PMP hollow fiber was uniformly purple, indicating that the heparin coating evenly covered its surface, indicating that UV pretreatment before coating facilitates the adhesion of the heparin coating to the PMP surface.

[0117] (3) Hydrophilic properties of heparin coatings prepared after UV pretreatment combined with heparin coating (Examples 1 and 2).

[0118] The results are as follows Figure 5 As shown, the water contact angles of the PMP hollow fiber membrane that was directly coated with heparin without UV pretreatment (Comparative Example 1) and the PMP hollow fiber membrane that was coated after UV pretreatment were tested at room temperature. It can be seen from the figure that after heparin coating after pretreatment, the water contact angle decreased from 87.4° to 75.1° (or 74.7°), indicating that the heparin coating formed by UV pretreatment of the grafted material and then coating has better hydrophilicity and can increase the coating effect of the heparin coating.

[0119] (4) Anticoagulant properties of heparin coating after UV pretreatment (Examples 1 and 2).

[0120] The anticoagulant effect of the heparin coating was tested by coagulation experiments. Figure 6 As shown in the figure, a large number of spotted thrombi are attached to the surface of the untreated PMP hollow fiber membrane (Comparative Example 1) after 6 hours of contact with blood. A small amount of thrombi are also formed on the surface of the fiber membrane that is directly coated with heparin without UV pretreatment after 6 hours of contact with blood. However, only a few spotted thrombi are formed on the surface of the fiber membrane that is coated after UV pretreatment after 6 hours of contact with blood. This shows that the heparin coating formed after UV pretreatment has the best anticoagulant effect and has better anticoagulant performance.

[0121] (5) Uniformity and coverage of directional heparin coating (Example 1).

[0122] The results are as follows Figure 7 As shown, the staining results show that compared with the unidirectional coating (Comparative Example 2), the coating direction is changed midway, which increases the coverage of heparin, makes the heparin coating more uniform, and improves the hydrophilicity and anticoagulant properties of the heparin coating.

[0123] (6) Uniformity and coverage of heparin coatings applied at different flow rates (Examples 1 and 3).

[0124] The results are as follows Figure 8As shown in the figure, the staining results show that the uniformity and coverage of the heparin coating are significantly improved when the flow rate of 0.3 LPM is used for coating compared with that of 1 LPM.

[0125] (7) Heparin coating uniformity and coverage at different coating times (Examples 2 and 4).

[0126] The results are as follows Figure 9 As shown in the figure, the staining results show that compared with the coating for 1 hour (0.5 hours of cyclic flushing and reverse flushing), the heparin coating coated for 4 hours (2 hours of cyclic flushing and reverse flushing) is significantly more uniform and has a higher heparin coverage.

[0127] (8) Heparin coating uniformity and coverage of heparin solutions with different concentrations (Examples 1 and 5).

[0128] The results are as follows Figure 10 As shown in the figure, the staining results show that compared with the 0.03% heparin solution, the heparin is more evenly attached to the material surface when the heparin solution with a mass concentration of 0.3% is used for coating.

[0129] (9) Uniformity and coverage of heparin coating fixed with EDC solutions of different concentrations (Examples 2 and 6).

[0130] The results are as follows Figure 11 As shown in FIG, the staining results show that, compared with the 0.001‰ EDC solution, the uniformity and coverage of the heparin coating are increased when the 0.03‰ EDC solution is used to fix the heparin coating.

[0131] Table 1 Performance test results of various embodiments

[0132]

[0133] This method utilizes plasma-UV or UV-ozone technology to stimulate the production of free radicals or oxygen-containing groups on the surface of the PMP hollow fiber membrane, which in turn triggers the formation of PEI grafted chains on the surface. This improves the hydrophilicity of the PMP hollow fiber membrane and enhances surface adhesion. It also introduces amino functional groups to promote the adhesion and binding of heparin to the surface. The heparin coating prepared by combining UV pretreatment with heparin-redirected coating is relatively uniform and exhibits excellent hydrophilic and anticoagulant properties, suggesting significant potential for application.

[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a composite heparin anticoagulant coating, characterized in that: include: 1) UV pretreatment: UV pretreatment is performed on a substrate material to initiate grafting of polyethyleneimine (PEI) onto the surface of the material; the substrate material is a PMP hollow fiber membrane; the UV pretreatment comprises: treating the substrate material in an argon plasma environment; treating the treated substrate material in an O2-containing environment; mixing a PEI solution with the substrate material and reacting them under UV irradiation; or activating the substrate material under a low-pressure mercury vapor lamp, mixing a PEI solution with the substrate material, and reacting them under UV irradiation; 2) Directional coating: a heparin solution is applied to the surface of the substrate material and fixed with an EDC solution; the coating direction is changed during the coating process.

2. The method for preparing the composite heparin anticoagulant coating according to claim 1, wherein: Use heparin solution for circulatory flushing at room temperature for 1-4 hours, then change the circulation direction and continue to circulate for 1-4 hours; and / or use EDC solution for circulatory flushing at room temperature for 0.5-2 hours, then change the circulation direction and continue to circulate for 0.5-2 hours.

3. The method for preparing the composite heparin anticoagulant coating according to claim 2, characterized in that: The flow rate of circulating flushing with heparin solution and / or EDC solution is 0.05-0.5 LPM.

4. The method for preparing the composite heparin anticoagulant coating according to any one of claims 1 to 3, characterized in that: The mass fraction of the heparin solution is 0.05%-0.3%, and the pH is 2-5; and / or the mass fraction of the EDC solution is 0.002‰-0.03‰, and the pH is 2-6.

5. The method for preparing the composite heparin anticoagulant coating according to claim 4, characterized in that: The solvent of the heparin solution and / or the EDC solution is disodium hydrogen phosphate-citric acid buffer solution.

6. The composite heparin anticoagulant coating prepared by the preparation method according to any one of claims 1 to 5.

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