Epoxy group modified zwitterionic polymer / heparin composite coating and preparation method thereof

Abstract

The invention discloses an epoxy group modified zwitterionic polymer / heparin composite coating and a preparation method thereof. The preparation method comprises the following steps: firstly, constructing an amino-containing adhesion layer on the surface of a substrate by adopting a dip-coating method; then, the substrate is soaked in a mixed solution of the zwitterionic polymer and the heparin, and grafting of the zwitterionic polymer and the heparin on the surface of the medical material is completed through incubation. The coating provided by the invention has excellent hydrophilicity, can form a hydration layer, provides a physical barrier, and remarkably prevents adhesion and colonization of microorganisms. The inhibition rate of the coating on escherichia coli and staphylococcus aureus exceeds 99%, protein adhesion is remarkably reduced in an anti-protein adhesion experiment, and the coating is simple in strategy design, has a potential application prospect in the aspect of preventing blood contact catheter related infection and thrombosis, and has a wide application prospect. The complication occurrence rate and the medical care cost can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of development of antibacterial and anticoagulant coating materials, and relates to an epoxy group-modified zwitterionic polymer / heparin composite coating and a preparation method thereof. Background Art

[0002] Medical devices play an indispensable role in clinical surgery, especially those that come into contact with blood, such as intravascular stents, extracorporeal circulation tubes, central venous catheters, and indwelling needles. Among them, the use of medical catheters accounts for more than 70%, and their main materials are polyvinyl chloride (PVC) and polyurethane (PU). However, the biocompatibility and blood compatibility of these materials are poor. During the process of intervention, use, and retention, medical catheters are prone to cause bacterial adhesion and proliferation, forming biofilms, and then leading to infection. In addition, when in direct contact with blood, it will activate the coagulation reaction caused by foreign matter, leading to plasma protein adsorption, activation of coagulation factors or platelets, and then promote the conversion of soluble fibrin into insoluble fibrin, ultimately causing serious complications such as coagulation and inflammation, and even endangering the patient's life. Therefore, it is of great significance to construct a coating with antibacterial and anticoagulant properties on the surface of medical catheters.

[0003] At present, intravenous injection of antibiotics and anticoagulants is a common method for preventing infection and thrombosis-related complications, but excessive anticoagulants and antibiotics may lead to problems such as antibiotic resistance, postoperative bleeding and thrombocytopenia. Studies have shown that zwitterions have excellent biocompatibility and blood compatibility. Its coating can form a hydration layer at the interface between the coating and the tissue, thereby having antifouling properties against proteins, red blood cells and bacteria, and has been widely used in the antibacterial and anticoagulant functionalization of biomaterials. For example, a Chinese patent application with publication number CN 114652904 A discloses a method for preparing a zwitterion hydrogel coating for anticoagulation, which has a complex preparation process, requires pretreatment of the substrate, and the hydrogel coating is easy to swell and lose water. This type of coating is combined with the substrate through physical action, has poor mechanical stability, is easy to fall off during use, and is difficult to control in thickness. Therefore, how to prepare an antibacterial and anticoagulant coating with high mechanical stability, controllable thickness, strong adhesion, and not easy to fall off on the surface of the substrate has become an urgent problem to be solved for the substrate. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides an epoxy group-modified zwitterionic polymer / heparin composite coating and a preparation method thereof, thereby solving the technical problems in the prior art that the zwitterionic hydrogel coating has poor mechanical stability when combined with a substrate, is easy to fall off during use, and has difficulty in controlling thickness.

[0005] The present invention is achieved through the following technical solutions: A method for preparing an epoxy group-modified zwitterionic polymer / heparin composite coating comprises the following steps: dissolving dopamine hydrochloride and polyethyleneimine in an aqueous solution of tris(hydroxymethyl)aminomethane hydrochloride) to prepare an aqueous solution, and immersing a substrate in the aqueous solution to prepare a substrate having an amino group-containing adhesion layer deposited thereon; The zwitterionic monomer and the epoxy group-containing monomer are added to a mixed solvent of N,N-dimethylformamide and water, and after being completely mixed and degassed, a thermal initiator is added, mixed and reacted to obtain an epoxy-modified zwitterionic polymer; The epoxy-modified zwitterionic polymer and heparin are dissolved in a carbodiimide aqueous solution for activation, and then the substrate deposited with the amino-containing adhesion layer is immersed in the activated aqueous solution for immersion reaction to obtain the epoxy-modified zwitterionic polymer / heparin composite coating.

[0006] Preferably, dopamine hydrochloride and polyethyleneimine are dissolved in a tris(hydroxymethylaminomethane) hydrochloride aqueous solution to form an aqueous solution, and the substrate is immersed in the aqueous solution to obtain a substrate deposited with an amino-containing adhesion layer. Specifically, dopamine hydrochloride and polyethyleneimine are dissolved in a tris(hydroxymethylaminomethane) hydrochloride aqueous solution in a mass ratio of (10-4):(1-3), the pH value of the aqueous solution is adjusted to 5-10, and then the substrate is immersed in the solution for 12-48 hours. After being taken out and cleaned, the substrate deposited with an ammonia-containing adhesion layer is obtained.

[0007] Preferably, the carbodiimide is at least one of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide, N-hydroxysuccinimide and morpholineethanesulfonic acid hydrate.

[0008] Preferably, the zwitterionic monomer is any one of 2-methacryloyloxyethyl phosphorylcholine, methacrylic acid carboxylic acid betaine and methacrylic acid sulfobetaine.

[0009] Preferably, the epoxy monomer is glycidyl methacrylate or allyl glycidyl methacrylate.

[0010] Preferably, the molar ratio of the zwitterionic monomer to the epoxy monomer is (1-9):(9-1).

[0011] Preferably, a thermal initiator is added and reacted after mixing, specifically: after adding the thermal initiator, mixing for 10 to 40 minutes, then placing the reactants at 25 to 80° C. for reaction for 3 to 8 hours, and terminating the reaction in an ice bath.

[0012] Preferably, after the epoxy-modified zwitterionic polymer and heparin are dissolved in an aqueous solution of carbodiimide, the concentration of the zwitterionic polymer is 2-20 mg / mL, and the concentration of the heparin is 2-10 mg / mL.

[0013] Preferably, the activation temperature is 20-65° C. and the activation time is 10-40 min.

[0014] An epoxy group-modified zwitterionic polymer / heparin composite coating is prepared by the above method.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: The invention discloses a preparation method of an epoxy group-modified zwitterionic polymer / heparin composite coating. The method firstly forms an amino-containing adhesion layer on the surface of a substrate by reacting dopamine hydrochloride and polyethyleneimine in a tris(hydroxymethylaminomethane) hydrochloride aqueous solution, and the dopamine hydrochloride and polyethyleneimine produce a synergistic effect. The dopamine hydrochloride and polyethyleneimine are dissolved in the tris(hydroxymethylaminomethane) hydrochloride aqueous solution, and an amino-containing adhesion layer is formed on the surface of the substrate, thereby providing abundant amino functional groups for subsequent polymerization reaction. The amino functional groups not only help the grafting of zwitterionic polymer and heparin, but also can be chemically bonded with epoxy groups, thereby significantly improving the adhesion of the coating. Then, the epoxy group-modified zwitterionic polymer and heparin are deposited on the surface of the amino-containing adhesion layer by polymerization reaction. Heparin, as a natural anticoagulant, can be combined with a variety of coagulation factors to inhibit coagulation reaction. The heparin in the coating can continuously play an anticoagulant role and effectively prevent thrombosis. During the deposition process of the epoxy-modified zwitterionic polymer and heparin, the epoxy group can bond with the amino group in the adhesion layer to form a stable chemical bond. This chemical bonding not only enhances the binding force between the zwitterionic polymer and the substrate, but also ensures that the heparin molecules can be firmly fixed in the coating and are not easy to fall off. In addition to chemical bonding, there is also an electrostatic bonding effect between heparin and the epoxy-modified zwitterionic polymer. The heparin molecule carries a negative charge, while the epoxy-modified zwitterionic polymer carries a positive charge, so there is a strong electrostatic attraction between the two. This electrostatic bonding further enhances the adhesion between heparin and the coating, ensuring that heparin can continue to play an anticoagulant role. In addition, the epoxy-modified zwitterionic polymer has excellent hydrophilicity and can form a hydration layer in an aqueous solution, providing a physical barrier and significantly preventing the adhesion and colonization of microorganisms. The experimental results show that the inhibition rate of the coating on Escherichia coli and Staphylococcus aureus exceeds 99%, and the protein adhesion is significantly reduced in the anti-protein adhesion experiment. Due to the use of chemical bonding and electrostatic bonding mechanisms, the coating can maintain a stable structure and performance during long-term use and is not prone to falling off or degradation. The coating has excellent antibacterial and anti-protein adhesion properties, and can significantly reduce the risk of blood-contact catheter-related infection. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 It is a schematic diagram of the structure of the coating surface of the present invention; Figure 2 The infrared spectrum (FT-IR) of the composite anticoagulation coating prepared in Examples 1 to 3 of the present invention; Figure 3 The water contact angle test diagram of the composite anticoagulation coating prepared in Examples 1 to 3 of the present invention; Figure 4 This is a test diagram of the heparin grafting amount of Examples 2, 4 and 5 of the present invention; Figure 5 Blank, PVC and Example 5 antibacterial rate test graph; Figure 6 The figures are anticoagulation test images of PVC and Example 6 after extracorporeal blood circulation, wherein (a) is an electronic photograph of PVC and Example 6 after extracorporeal blood circulation; and (b) is a scanning electron microscope image of surface thrombus.

[0018] Among them, 1. substrate, 2. adhesion layer, 3. functional layer DETAILED DESCRIPTION In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0019] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0020] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0021] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0022] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0023] The present invention provides a method for preparing an epoxy group-modified zwitterionic polymer / heparin composite coating, comprising the following steps: S1: dissolving the mussel-inspired adhesion material, i.e., dopamine hydrochloride and polyethyleneimine, in a tris(hydroxymethylaminomethane) hydrochloride aqueous solution to prepare an aqueous solution, and immersing a substrate in the aqueous solution to obtain a substrate having an amino-containing adhesion layer deposited thereon; specifically, the dopamine hydrochloride and polyethyleneimine are dissolved in a tris(hydroxymethylaminomethane) hydrochloride aqueous solution in a mass ratio of (10-4):(1-3), and the pH value of the aqueous solution is adjusted to 5-10 using sodium hydroxide and hydrochloric acid, and then the substrate is immersed in the solution for 12-48 hours, and after being taken out and cleaned, the substrate having an ammonia-containing adhesion layer deposited thereon is obtained.

[0024] The substrate may be a medical material, specifically, a medical material in contact with blood, such as a medical catheter, a vascular stent, and a heart valve.

[0025] S2: adding zwitterionic monomer and epoxy-containing monomer in a molar ratio of (1-9):(9-1) to a mixed solvent of N,N-dimethylformamide and water, wherein the volume ratio of N,N-dimethylformamide to water in the mixed solvent is 1:3, and after complete mixing and degassing, adding 1-5 wt% of thermal initiator, mixing for 10-40 minutes, reacting at 25-80°C for 3-8 hours, and terminating the reaction in an ice bath. After the reaction is completed, dialyzing with distilled water for 1-7 days, and finally freeze-drying to obtain an epoxy-modified zwitterionic polymer; Wherein, the thermal initiator includes any one of azobisisobutyronitrile, azobisisoheptanenitrile, azobisisobutylamidine hydrochloride, potassium persulfate and ammonium persulfate.

[0026] S3: The epoxy-modified zwitterionic polymer and heparin with a molecular weight of 3000-8000 kD are dissolved in an aqueous solution of carbodiimide (WSC), and activated at 20-65°C for 10-40 min, wherein the concentration of the epoxy-modified zwitterionic polymer is 2-20 mg / mL, and the concentration of heparin is 2-20 mg / mL. Then, the substrate deposited with the amino-containing adhesion layer is immersed in the activated aqueous solution, and the reaction is carried out at 25-65°C for 6-48 h to obtain the epoxy-modified zwitterionic polymer / heparin composite coating.

[0027] The carbodiimide is at least one of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide, N-hydroxysuccinimide and morpholineethanesulfonic acid hydrate. The concentration of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide is 0.5-2 mg / mL, the concentration of N-hydroxysuccinimide is 0.1-0.6 mg / mL, and the concentration of morpholineethanesulfonic acid hydrate is 8-10 mg / mL.

[0028] The zwitterionic monomer is any one of 2-methacryloyloxyethyl phosphorylcholine, methacrylic acid carboxylic acid betaine and methacrylic acid sulfonic acid betaine.

[0029] The epoxy monomer is glycidyl methacrylate or allyl glycidyl methacrylate.

[0030] like Figure 1 As shown, the epoxy group-modified zwitterionic polymer / heparin composite coating of the present invention is composed of a substrate 1, an adhesive layer 2 and a functional layer 3 sequentially deposited on the substrate 1. The adhesive layer 2 is an amino adhesive layer, which is composed of a mussel-inspired adhesive material dopamine hydrochloride and a polyethyleneimine cross-linking layer; the functional layer is composed of an epoxy group-modified zwitterionic polymer and heparin; the epoxy group-modified zwitterionic polymer is prepared by a free radical polymerization method; The general structural formula of the epoxy group-modified zwitterionic polymer prepared in the present invention is as follows (I):

[0031] In the formula, R1 and R2 are H or CH3, R3 is a related functional group of phosphorylcholine (PC), sulfobetaine (SB) or carboxybetaine (CB), and R4 is a related functional group of an epoxy-containing monomer; x=300~1000, y=100~800.

[0032] Mussel-inspired dopamine hydrochloride, as a universal adhesive material, can easily adhere to the surface of materials of various shapes and sizes. Grafted zwitterionic polymers and heparin can effectively change the surface hydrophobicity of medical materials, form a hydrophilic surface and establish a hydration layer, thereby preventing microbial adhesion and enhancing antibacterial and anticoagulant properties. This method does not require complex surface treatment. The covalent bonding of the hydrophilic zwitterionic polymer and the heparin composite coating is achieved through the mussel biomimetic adhesion layer constructed in the aqueous solution, which fundamentally solves the problem of coating shedding due to insufficient adhesion.

[0033] The invention discloses an epoxy group-modified zwitterionic polymer / heparin composite coating and a preparation method thereof, which mainly comprises an adhesive layer, a zwitterionic polymer and a heparin composite layer. The specific steps are as follows: first, an amino-containing adhesive layer is constructed on the surface of a medical material by a dip coating method to obtain a medical material containing an amino-containing adhesive layer; then, the medical material coated with the amino-containing adhesive layer is immersed in a mixed solution of an epoxy group-modified zwitterionic polymer and heparin for incubation, thereby realizing the grafting of the oxygen group-modified zwitterionic polymer and heparin on the surface of the medical material. The invention provides a composite coating with excellent biocompatibility and blood compatibility, which combines a zwitterionic polymer with anti-biological contamination and heparin with excellent anticoagulant effect, and significantly improves the anticoagulant effect and antibacterial performance of the composite coating by combining a biologically inert zwitterionic polymer with a biologically active heparin. The invention achieves excellent durability by grafting and fixing the zwitterionic polymer and heparin composite coating on the surface of the material. The composite anticoagulant coating of the invention has broad application prospects in the field of biomedical engineering.

[0034] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0035] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0036] Example 1 Step 1: construct an amino-containing adhesion layer on the surface of a medical PVC sheet by dip coating, specifically: dopamine hydrochloride and polyethyleneimine are dissolved in a 50 mmol tris(hydroxymethyl)aminomethane hydrochloride aqueous solution at a mass ratio of 1:1, and the pH value is adjusted to 8.5 with sodium hydroxide and hydrochloric acid to prepare a solution with a concentration of 2 mg / mL of dopamine hydrochloride and polyethyleneimine, and the solution is immersed in the PVC sheet and deposited at 25°C for 24 h. Afterwards, it is rinsed three times with deionized water to remove the components that are not firmly bonded.

[0037] Step 2, methacrylic acid sulfobetaine and methacrylate glycidyl ester were added to a mixed solvent of N,N-dimethylformamide and deionized water in a volume ratio of 1:3 at a molar ratio of 1:9, and the mixture was thoroughly mixed and degassed. Subsequently, 3 wt% of a thermal initiator was added to the solution and mixed for another 20 min. The solution was reacted at 60°C for 5 h, the reaction was terminated in an ice bath, dialyzed with distilled water for 7 days, and freeze-dried to obtain a zwitterionic polymer.

[0038] Step 3, immersing the PVC sheet containing the amino adhesive layer obtained in step 1 in a WSC solution containing 2 mg / mL zwitterionic polymer and 2 mg / mL heparin, and reacting at 25° C. for 24 hours.

[0039] Example 2 Step 1 is the same as step 1 in Example 1.

[0040] Step 2, methacrylic acid sulfobetaine and methacrylate glycidyl ester were added to a mixed solvent of N,N-dimethylformamide and deionized water in a volume ratio of 1:3 in a molar ratio of 3:7, and the mixture was thoroughly mixed and degassed. Subsequently, 3 wt% of a thermal initiator was added to the solution and mixed for another 20 minutes. The solution was reacted at 60°C for 5 hours, the reaction was terminated in an ice bath, dialyzed with distilled water for 7 days, and freeze-dried to obtain a zwitterionic polymer.

[0041] Step 3 is the same as step 3 in Example 1.

[0042] Example 3 Step 1 is the same as step 1 in Example 1.

[0043] Step 2, methacrylic acid sulfobetaine and methacrylate glycidyl ester were added to a mixed solvent of N,N-dimethylformamide and deionized water in a volume ratio of 1:3 at a molar ratio of 5:5, and the mixture was thoroughly mixed and degassed. Subsequently, 3 wt% of a thermal initiator was added to the solution and mixed for another 20 minutes. The solution was reacted at 60°C for 5 hours, the reaction was terminated in an ice bath, dialyzed with distilled water for 7 days, and freeze-dried to obtain a zwitterionic polymer.

[0044] Step 3 is the same as step 3 in Example 1.

[0045] Figure 2 The FT-IR test diagram of the composite anticoagulation coating prepared in Examples 1 to 3 of the present invention shows that the 1540-1695 cm -1 The range belongs to the stretching vibration peak of the carbon-carbon double bond. The disappearance of the peak signal in this range proves that the monomer has undergone polymerization reaction under the conditions of 60°C with azobisisobutylamidine hydrochloride (AIBA) as the initiator. 1726 cm -1 and 1482 cm-1 The absorption peaks at are the stretching vibration peaks of the ester group C=O and -CH 2 -N + Characteristic absorption peak of 1184 cm -1 and 1039cm -1 The absorption peaks at 3 Compared with the original PVC, the surface of the deposited PVC has asymmetric stretching vibration peaks of S=O and symmetric stretching vibration peaks at 3000~3750 cm -1 There are obvious absorption peaks in the range, which are the characteristic absorption peaks of NH, -NH2 and -OH.

[0046] Figure 3 The test results of the surface water contact angle of the composite coatings prepared in Examples 1 to 3 show that the water contact angles of the composite anticoagulation coatings prepared in Examples 1 to 3 are all less than 90 degrees, indicating that the coating surface is hydrophilic and has wettability.

[0047] Example 4 Step 1 is the same as step 1 in Example 1.

[0048] Step 2 is the same as step 2 in Example 2.

[0049] Step 3, immersing the PVC sheet containing the amino adhesive layer obtained in step 1 in a WSC solution containing 2 mg / mL zwitterionic polymer and 2 mg / mL heparin, and reacting at 25° C. for 12 hours.

[0050] Example 5 Step 1 is the same as step 1 in Example 1.

[0051] Step 2 is the same as step 2 in Example 2.

[0052] Step 3, immersing the PVC sheet containing the amino adhesive layer obtained in step 1 in a WSC solution containing 2 mg / mL zwitterionic polymer and 2 mg / mL heparin, and reacting at 25° C. for 48 hours.

[0053] Figure 4 This is a test diagram of the heparin grafting amount of Examples 2, 4 and 5. The heparin grafting amount is related to the grafting time, and the reaction is saturated after 24 hours.

[0054] Figure 5 The antibacterial performance test diagram of the composite anticoagulant coating prepared in Example 5 of the present invention is shown in Figure 5. During the experiment, it was compared with a culture medium containing only a culture medium (marked as a blank group) and a culture medium containing PVC (marked as a PVC group). The plate colony counting method was used to select Gram-negative bacteria (Escherichia coli, E. coli ) and Gram-positive bacteria (Staphylococcus aureus,S. aureus ) for quantitative evaluation. The figure shows the growth of colonies on agar plates. It can be seen from the figure that the number of colonies in the coating group is significantly reduced compared with the blank group and the PVC group, showing excellent antibacterial properties. The temperature of the antibacterial experiment was 37°C and the time was 24h.

[0055] Example 6 Step 1 is the same as step 1 in Example 2.

[0056] Step 2 is the same as step 2 in Example 2.

[0057] Step 3 is the same as step 3 in Example 2.

[0058] Figure 6 This is a test diagram of the anticoagulant performance of the composite anticoagulant coating prepared in Example 6 of the present invention. Fresh anticoagulated rabbit blood was used to establish extracorporeal blood circulation through a peristaltic pump. After 6 hours of extracorporeal blood circulation, photos were taken for observation. From Figure a, the thrombosis on the surface of the simple PVC and the surface of the composite anticoagulant coating prepared in Example 6 can be clearly observed. There was obvious thrombosis in the PVC pipe, which caused the catheter to be blocked. Basically no thrombosis was found on the surface of the composite anticoagulant coating prepared in Example 6, and the catheter remained unobstructed. b is a scanning electron microscopic image of thrombus on the surface of the simple PVC and the composite anticoagulant coating prepared in Example 6 after extracorporeal blood circulation. After 6 hours of extracorporeal blood circulation, the surface of the catheter that was in contact with the blood was observed by scanning electron microscopy. As shown in the figure, a large amount of platelets and fibrin were adhered to the surface without the coating, resulting in the formation of thrombus, and basically no platelet and fibrin network was found on the surface with the coating, which indicates that the coating can prevent the coagulation process by reducing the coagulation response caused by the activation of foreign matter.

[0059] Example 7 A method for preparing an epoxy group-modified zwitterionic polymer / heparin composite coating comprises the following steps: S1: dissolving the mussel-inspired adhesion material, i.e., dopamine hydrochloride and polyethyleneimine, in a tris(hydroxymethylaminomethane) hydrochloride aqueous solution to prepare an aqueous solution, and immersing a substrate in the aqueous solution to obtain a substrate having an amino-containing adhesion layer deposited thereon; specifically, the dopamine hydrochloride and polyethyleneimine are dissolved in a tris(hydroxymethylaminomethane) hydrochloride aqueous solution in a mass ratio of 10:1, and the pH value of the aqueous solution is adjusted to 5 using sodium hydroxide and hydrochloric acid, and then the substrate is immersed in the solution for 12 hours. After being taken out and cleaned, the substrate having an ammonia-containing adhesion layer deposited thereon is obtained.

[0060] S2: adding zwitterionic monomer and epoxy-containing monomer in a molar ratio of 1:9 to a mixed solvent of N,N-dimethylformamide and water, wherein the volume ratio of N,N-dimethylformamide to water in the mixed solvent is 1:3, and after complete mixing and degassing, adding 1wt% of thermal initiator, mixing for 10 minutes, reacting at 80°C for 3 hours, and terminating the reaction in an ice bath. After the reaction is completed, dialyzing with distilled water for 1 day, and finally freeze-drying to obtain an epoxy-modified zwitterionic polymer; Wherein, the thermal initiator is azobisisobutyronitrile.

[0061] S3: The epoxy-modified zwitterionic polymer and heparin with a molecular weight of 3000-4000 kD are dissolved in an aqueous solution of carbodiimide (WSC), and activated at 20°C for 40 min, wherein the concentration of the epoxy-modified zwitterionic polymer is 2 mg / mL, and the concentration of heparin is 2 mg / mL, and then the substrate deposited with the amino-containing adhesion layer is immersed in the activated aqueous solution, and the immersion reaction is carried out at 25°C for 48 h to obtain the epoxy-modified zwitterionic polymer / heparin composite coating.

[0062] The carbodiimide is N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide with a concentration of 1 mg / mL.

[0063] The zwitterionic monomer is 2-methacryloyloxyethyl phosphorylcholine.

[0064] The epoxy monomer is glycidyl methacrylate.

[0065] Example 8 A method for preparing an epoxy group-modified zwitterionic polymer / heparin composite coating comprises the following steps: S1: dissolving the mussel-inspired adhesion material, i.e., dopamine hydrochloride and polyethyleneimine, in a tris(hydroxymethylaminomethane) hydrochloride aqueous solution to prepare an aqueous solution, and immersing a substrate in the aqueous solution to obtain a substrate having an amino-containing adhesion layer deposited thereon; specifically, the dopamine hydrochloride and polyethyleneimine are dissolved in a tris(hydroxymethylaminomethane) hydrochloride aqueous solution in a mass ratio of 4:3, and the pH value of the aqueous solution is adjusted to 10 using sodium hydroxide and hydrochloric acid, and then the substrate is immersed in the solution for 48 hours. After being taken out and cleaned, the substrate having an ammonia-containing adhesion layer deposited thereon is obtained.

[0066] S2: Adding zwitterionic monomers and epoxy-containing monomers in a molar ratio of 9:1 to a mixed solvent of N,N-dimethylformamide and water, wherein the volume ratio of N,N-dimethylformamide to water in the mixed solvent is 1:3, and after complete mixing and degassing, adding 5 wt% of a thermal initiator, mixing for 40 minutes, reacting at 80°C for 3 hours, and terminating the reaction in an ice bath. After the reaction is completed, dialyzing with distilled water for 7 days, and finally freeze-drying, to obtain an epoxy-modified zwitterionic polymer; Wherein, the thermal initiator is azobisisobutylamidine hydrochloride.

[0067] S3: The epoxy-modified zwitterionic polymer and heparin with a molecular weight of 5000-8000 kD are dissolved in an aqueous solution of carbodiimide (WSC), and activated at 65°C for 10 min, wherein the concentration of the epoxy-modified zwitterionic polymer is 20 mg / mL, and the concentration of heparin is 20 mg / mL, and then the substrate deposited with the amino-containing adhesion layer is immersed in the activated aqueous solution, and the immersion reaction is carried out at 65°C for 6 h to obtain the epoxy-modified zwitterionic polymer / heparin composite coating.

[0068] The carbodiimide is 0.4 mg / mL of N-hydroxysuccinimide.

[0069] The zwitterionic monomer is methacrylic acid betaine.

[0070] The epoxy monomer is allyl glycidyl ester.

[0071] Example 9 A method for preparing an epoxy group-modified zwitterionic polymer / heparin composite coating comprises the following steps: S1: dissolving the mussel-inspired adhesion material, i.e., dopamine hydrochloride and polyethyleneimine, in a tris(hydroxymethylaminomethane) hydrochloride aqueous solution to prepare an aqueous solution, and immersing a substrate in the aqueous solution to obtain a substrate having an amino-containing adhesion layer deposited thereon; specifically, the dopamine hydrochloride and polyethyleneimine are dissolved in a tris(hydroxymethylaminomethane) hydrochloride aqueous solution in a mass ratio of 6:2, and the pH value of the aqueous solution is adjusted to 8 using sodium hydroxide and hydrochloric acid, and then the substrate is immersed in the solution for 30 hours. After being taken out and cleaned, the substrate having an ammonia-containing adhesion layer deposited thereon is obtained.

[0072] S2: adding zwitterionic monomer and epoxy-containing monomer in a molar ratio of 5:5 to a mixed solvent of N,N-dimethylformamide and water, wherein the volume ratio of N,N-dimethylformamide to water in the mixed solvent is 1:3, and after complete mixing and degassing, adding 2wt% of thermal initiator, mixing for 30 minutes, reacting at 50°C for 5 hours, and terminating the reaction in an ice bath. After the reaction is completed, dialyzing with distilled water for 3 days, and finally freeze-drying to obtain an epoxy-modified zwitterionic polymer; Wherein, the thermal initiator is ammonium persulfate.

[0073] S3: The epoxy-modified zwitterionic polymer and heparin with a molecular weight of 5000-6000 kD are dissolved in an aqueous solution of carbodiimide (WSC), and activated at 40°C for 30 min, wherein the concentration of the epoxy-modified zwitterionic polymer is 10 mg / mL, and the concentration of heparin is 10 mg / mL, and then the substrate deposited with the amino-containing adhesion layer is immersed in the activated aqueous solution, and the immersion reaction is carried out at 30°C for 20 hours to obtain the epoxy-modified zwitterionic polymer / heparin composite coating.

[0074] The carbodiimide was 9 mg / mL morpholineethanesulfonic acid hydrate.

[0075] The zwitterionic monomer is methacrylate sulfobetaine.

[0076] The epoxy monomer is glycidyl methacrylate.

[0077] The invention relates to an epoxy group-modified zwitterionic polymer / heparin composite coating and a preparation method thereof. The coating comprises an adhesion layer, an epoxy group-modified zwitterionic polymer and a heparin composite layer. The main steps are: first, an amino-containing adhesion layer is constructed on the surface of a medical material by a dip coating method; then, the medical material is immersed in a mixed solution of zwitterionic polymer and heparin, and the zwitterionic polymer and heparin are grafted on the surface of the medical material through incubation. The coating of the invention has excellent hydrophilicity, can form a hydration layer, provide a physical barrier, and significantly prevent the adhesion and colonization of microorganisms. Experimental results show that the inhibition rate of the coating on Escherichia coli and Staphylococcus aureus exceeds 99%, and protein adhesion is significantly reduced in an anti-protein adhesion experiment. In addition, an in vitro blood circulation experiment verifies the effectiveness of the product of the invention in preventing thrombosis. The coating strategy of the invention is simple in design, has potential application prospects in preventing blood contact catheter-related infection and thrombosis, and helps to reduce the incidence of complications and medical care costs.

[0078] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing an epoxy group-modified zwitterionic polymer / heparin composite coating, characterized in that: The following steps are involved: dissolving dopamine hydrochloride and polyethyleneimine in an aqueous solution of tris(hydroxymethyl)aminomethane hydrochloride) to prepare an aqueous solution, and immersing a substrate in the aqueous solution to prepare a substrate having an amino group-containing adhesion layer deposited thereon; The zwitterionic monomer and the epoxy group-containing monomer are added to a mixed solvent of N,N-dimethylformamide and water, and after being completely mixed and degassed, a thermal initiator is added, mixed and reacted to obtain an epoxy-modified zwitterionic polymer; The epoxy-modified zwitterionic polymer and heparin are dissolved in a carbodiimide aqueous solution for activation, and then the substrate deposited with the amino-containing adhesion layer is immersed in the activated aqueous solution for immersion reaction to obtain the epoxy-modified zwitterionic polymer / heparin composite coating.

2. The method for preparing a zwitterionic polymer / heparin composite coating containing epoxy groups according to claim 1, characterized in that: Dopamine hydrochloride and polyethyleneimine are dissolved in a tris(hydroxymethylaminomethane) hydrochloride aqueous solution to prepare an aqueous solution, and a substrate is immersed in the aqueous solution to obtain a substrate deposited with an amino-containing adhesion layer. Specifically, dopamine hydrochloride and polyethyleneimine are dissolved in a tris(hydroxymethylaminomethane) hydrochloride aqueous solution in a mass ratio of (10-4):(1-3), the pH value of the aqueous solution is adjusted to 5-10, and then the substrate is immersed in the solution for 12-48 hours. After being taken out and cleaned, the substrate deposited with an amino-containing adhesion layer is obtained.

3. The method for preparing a zwitterionic polymer / heparin composite coating containing epoxy groups according to claim 1, characterized in that: The carbodiimide is at least one of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide, N-hydroxysuccinimide and morpholineethanesulfonic acid hydrate.

4. The method for preparing an epoxy group-modified zwitterionic polymer / heparin composite coating according to claim 1, characterized in that: The zwitterionic monomer is any one of 2-methacryloyloxyethyl phosphorylcholine, methacrylic acid carboxylic acid betaine and methacrylic acid sulfobetaine.

5. The method for preparing an epoxy group-modified zwitterionic polymer / heparin composite coating according to claim 1, characterized in that: The epoxy monomer is glycidyl methacrylate or allyl glycidyl methacrylate.

6. The method for preparing an epoxy group-modified zwitterionic polymer / heparin composite coating according to claim 1, characterized in that: The molar ratio of the zwitterionic monomer to the epoxy monomer is (1-9):(9-1).

7. The method for preparing an epoxy group-modified zwitterionic polymer / heparin composite coating according to claim 1, characterized in that: Add a thermal initiator and react after mixing. Specifically, after adding the thermal initiator, mix for 10 to 40 minutes, then place the reactants at 25 to 80° C. for 3 to 8 hours, and terminate the reaction in an ice bath.

8. The method for preparing an epoxy group-modified zwitterionic polymer / heparin composite coating according to claim 1, characterized in that: After the epoxy-modified zwitterionic polymer and heparin are dissolved in an aqueous solution of carbodiimide, the concentration of the zwitterionic polymer is 2-20 mg / mL, and the concentration of the heparin is 2-10 mg / mL.

9. The method for preparing a zwitterionic polymer / heparin composite coating containing epoxy groups according to claim 1, characterized in that: The activation temperature is 20-65°C and the activation time is 10-40 min.

10. An epoxy group-modified zwitterionic polymer / heparin composite coating, characterized in that: Prepared by the method according to any one of claims 1 to 9.

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