A self-expanding medical suture and its preparation method

Abstract

This invention provides a self-expanding medical suture and its preparation method. The preparation steps involve first preparing a liquid prepolymer polymer solution, which has the ability to be photocured and crosslinked. Then, the prepolymer polymer is coated onto the surface of a commercially available ordinary medical vascular suture using an impregnation-lift method. Finally, the prepolymer polymer on the suture surface coating is crosslinked by photocuring to form a network crosslinked structure with swelling capacity. The resulting self-expanding medical suture has mechanical and operational properties comparable to the original suture, such as breaking strength, ease of use, and toughness. The coating material has good biocompatibility, and the immune rejection reaction is controllable when applied to tissues, resulting in high safety.

Description

Technical Field

[0001] This invention relates to the field of medical sutures and their preparation methods, and particularly to a self-expanding medical suture and its preparation method. Background Technology

[0002] Surgical suturing is an essential step in the vast majority of vascular surgeries. When using medical sutures to suture or anastomose blood vessels, each time the needle passes through the vessel wall, it leaves a needle prick. When the diameter ratio of the needle to the suture (needle diameter ratio) is large—meaning the needle diameter is significantly larger than the suture diameter—the suture cannot tightly fill the needle prick, allowing blood to seep out. Significant bleeding can obstruct the surgeon's view, hindering accurate positioning and making delicate vascular suturing or anastomosis procedures difficult. Furthermore, if the patient's constitution or underlying medical conditions make intraoperative bleeding difficult to control, bleeding from the suture or anastomosis site may require additional blood transfusions, posing a safety risk and potentially increasing treatment costs. Currently, most commonly used medical sutures employ perforated needle technology. The diameter of the suture needle is inevitably larger than that of the suture. However, the medical sutures used for vascular suturing are mostly 5-0 sutures or even smaller sutures, with a diameter of only about 0.1 mm. But in order to ensure the maneuverability of the suture needle during suturing, the penetrating power of the tissue, and to consider the difficulty of the manufacturing process, it is difficult to match the diameter of the suture needle with that of the suture. As a result, the needle diameter ratio of medical sutures used for vascular suturing is often between 2:1 and 3:1, which can easily lead to the problem of blood seeping from the needle hole during vascular suturing / anastomosis.

[0003] Therefore, overcoming the problem of needle hole bleeding during vascular suturing or anastomosis caused by the large needle diameter of current medical sutures, and providing a medical suture that can appropriately increase the needle diameter ratio to seal the needle holes during vascular suturing or anastomosis, thereby reducing the risk of bleeding, is of profound significance.

[0004] A search of existing technologies revealed that Ethicon, Inc. possesses a Hemo-seal™ technology, which involves cutting the tip of the suture to reduce its volume, allowing it to be fitted with piercing needles with smaller apertures (correspondingly smaller needle diameters). Medical sutures produced using this method have a significantly lower needle diameter ratio compared to ordinary medical sutures, which can reduce the incidence of needle hole bleeding during vascular suturing or anastomosis to some extent.

[0005] However, this technique has some drawbacks: 1) Cutting the suture tip and reducing the volume of the suture in that area reduces the mechanical strength of that area and the connection strength between the needle and thread, increasing the risk of suture breakage and needle-thread separation during use; 2) The principle of reducing the needle diameter ratio in this method is to match the suture with a smaller diameter needle. However, a smaller needle diameter is not conducive to the surgeon's clamping, puncture, and suturing operations during surgery, and the usability of medical sutures is affected to some extent; 3) The needle diameter ratio of medical sutures produced by this method can only approach 1:1 infinitely, and it is difficult to reach or slightly reduce it below 1:1. That is, the suture cannot completely fill the needle hole left by the blood vessel wall through which the needle passes, and the risk of bleeding cannot be completely controlled. Summary of the Invention

[0006] Therefore, this invention proposes a self-expanding medical suture and its preparation method to solve the above problems.

[0007] The technical solution of this invention is achieved as follows: A method for preparing a self-expanding medical suture includes the following steps:

[0008] S1. Synthesis of polyethylene glycol-methacrylate prepolymer:

[0009] Dissolve 0.25–3 parts of polyethylene glycol (PEG) in 5–30 parts of solvent (5–10% w / v), and under a nitrogen atmosphere of 4–6 kPa, add a linker or react directly to graft methacrylate derivatives onto the polyethylene glycol backbone to synthesize polyethylene glycol-methacrylate prepolymer.

[0010] S2, Dip-in Lift Coating:

[0011] 0.25–10 parts of the above-mentioned polyethylene glycol-methacrylate prepolymer and 0.01–3 parts of photoinitiator (0.05–1% w / v) were dissolved in 5–30 parts of solvent to obtain a coating solution (5–25% w / v); then, the prepolymer was coated on the surface of commercially available ordinary medical vascular sutures by dip-coating at a lifting speed of 1–20 cm / min to obtain a pre-crosslinked suture.

[0012] S3, Photocuring Crosslinking:

[0013] Exposed the pre-crosslinked suture to ultraviolet light at 190–380 nm (~12 mW / cm²). -2 Photopolymerization is carried out for 1-5 minutes, and the prepolymer on the suture surface spontaneously crosslinks to form a network structure. After drying, a self-expanding medical suture is obtained.

[0014] Preferably, the concentration of the polyethylene glycol solution in step S1 is 5% to 10%.

[0015] Preferably, the solvent includes, but is not limited to, tetrahydrofuran (THF), toluene, chloroform, xylene, and dimethyl sulfoxide (DMSO).

[0016] Preferably, the linker in step S1 includes, but is not limited to, succinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 2-hydroxypropane-1,2,3-tricarboxylic acid, 1-hydroxypropane-1,2,3-tricarboxylic acid, 1-propene-1,2,3-tricarboxylic acid, propane-1,2,3-tricarboxylic acid, 2-hydroxybutane-1,2,4-tricarboxylic acid, 1-hydroxybutane-1,2,4-tricarboxylic acid, 1-butene-1,2,4-tricarboxylic acid, and benzene-1,3,5-tricarboxylic acid.

[0017] Preferably, the concentration of the coating solution in step S2 is 5-25% w / v.

[0018] Preferably, the concentration of the photoinitiator in step S2 is 0.05–1% w / v.

[0019] Preferably, step S1, which synthesizes the polyethylene glycol-methacrylate prepolymer, involves dissolving 0.15 parts of polyethylene glycol with an average molecular weight of 5000 and 0.35 parts of adipic acid in 10 parts of anhydrous tetrahydrofuran (5% w / v) under a nitrogen atmosphere at a pressure of 5 kPa. The mixture is stirred at 800 rpm for 1 h in a water bath at 70°C. The pressure is then reduced to 3 kPa, and the reaction is continued for 15 h. Then, 3 parts of glycerol are added under a nitrogen atmosphere, and the reaction is continued for 30 h. Finally, 10 parts of diethyl ether are added to precipitate the product, and the product is dried at room temperature for 48 h to obtain PEGAG. One part of PEGAG was dissolved in 20 parts of anhydrous THF (5% w / v), then 4 parts of ethyl 2-aminomethacrylate (AEMA) and 0.02 parts of catalyst Sn(Oct)2 (0.1% w / v) were added. The solution was stirred at 25°C for 6 hours under a nitrogen atmosphere, and then 10 parts of diethyl ether were added to precipitate the product. The product was then dried in a vacuum oven for 3 days to obtain the photocurable pre-crosslinked polymer PEGAG-A.

[0020] Preferably, the method for synthesizing the polyethylene glycol-methacrylate prepolymer in step S1 further includes dissolving 1 part of polyethylene glycol with an average molecular weight of 8000 and 2 parts of 2-hydroxypropane-1,2,3-tricarboxylic acid (CA) in 20 parts of DMSO (15% w / v) under a nitrogen atmosphere of 5 kPa, and stirring at 900 rpm for 1 h in an 80°C water bath. The pressure is then reduced to 3 kPa, and the reaction is continued with stirring for 15 h. After cooling to room temperature, 1 part of N-hydroxysuccinimide (NHS) and 2 parts of 1-ethyl 3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) are added to activate the carboxylic acid groups. After stirring for 2 h, 4 parts of 2-aminomethacrylate (AEMA) are added, and the mixture is continuously stirred at room temperature for 24 hours. The mixture is then purified by dialysis with deionized water (MWCO: 3500) for 3 days. Finally, it is filtered, evaporated, and lyophilized to obtain the photocurable pre-crosslinked polymer PEGC-A.

[0021] Preferably, the method for synthesizing the polyethylene glycol-methacrylate prepolymer in step S1 further includes dissolving 2 parts of polyethylene glycol with an average molecular weight of 10000 Da and 4 parts of 5-demethylborene-2-carboxylic acid in 20 parts of chloroform (10% w / v), and adding 1 part of 4-(dimethylamino)pyridine (DMAP). The solution is heated to 45°C, and 0.4 parts of dibutyl dicarbonate (Boc2O) is added to the flask using a syringe. After 20 hours, cold water is added to quench the reaction. Then, sodium chloride (1 g of sodium chloride per 100 mL of solution) is added, and the reactants are precipitated in 10 parts of supercooled (4°C) acetone. The precipitate is filtered and dissolved in 20 parts of deionized water to obtain the PEG-Nor pre-crosslinked polymer, which is stored at 20°C until use.

[0022] Furthermore, the self-expanding medical suture has a porous mesh structure, which reaches swelling equilibrium after 10 minutes of contact with liquid, with a swelling rate of 200%.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] The self-expanding medical suture prepared by this invention involves first preparing a liquid prepolymer polymer solution. This prepolymer polymer possesses photocurable cross-linking capabilities. Subsequently, the prepolymer polymer is coated onto the surface of a commercially available ordinary medical vascular suture using an impregnation-lift method. Finally, photocuring is employed to cross-link the prepolymer polymer on the suture surface coating, forming a network cross-linked structure with swelling capacity. This invention, by forming a coating on the suture surface, endows the suture with the ability to appropriately expand in volume upon entering tissue and contacting liquid, effectively reducing the needle diameter ratio. In vascular anastomosis / suturing applications, it can tightly fill the needle holes caused by needle punctures, achieving a watertight seal and preventing blood leakage. Furthermore, this preparation method does not damage or alter the intrinsic properties of the original suture; therefore, the self-expanding suture possesses mechanical and operational properties comparable to the original suture, such as breaking strength, ease of use, and toughness. The coating material exhibits good biocompatibility, with controllable immune rejection reactions when applied to tissue, resulting in high safety. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the photocuring crosslinking synthesis of hydrogels.

[0026] Figure 2 This is a schematic diagram of the synthesis of PEGAG-A in Example 1;

[0027] Figure 3 This is a schematic diagram of the synthesis of PEGC-A in Example 2;

[0028] Figure 4 This is a schematic diagram of the PEG-Nor synthesis in Example 3;

[0029] Figure 5 SEM images of the hydrogel;

[0030] Figure 6 This is a swelling trend chart for self-expanding medical sutures. Detailed Implementation

[0031] To better understand the technical content of this invention, specific embodiments are provided below to further illustrate the invention.

[0032] Unless otherwise specified, the experimental methods used in the embodiments of this invention are all conventional methods.

[0033] Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available.

[0034] Example 1

[0035] 1. Synthesis of polyethylene glycol-methacrylate prepolymer:

[0036] Under a nitrogen atmosphere of 5 kPa, 0.15 parts of polyethylene glycol with an average molecular weight of 5000 and 0.35 parts of adipic acid (AA) were dissolved in 10 parts of anhydrous THF tetrahydrofuran (5% w / v), and the mixture was stirred at 800 rpm for 1 h in a water bath at 70 °C. The pressure was then reduced to 3 kPa, and the reaction was continued with stirring for 15 h. Then, 3 parts of glycerol were added under a nitrogen atmosphere, and the reaction was continued with stirring for 30 h. Finally, 10 parts of diethyl ether were added to precipitate the product, and the product was dried at room temperature for 48 h to obtain PEGAG. One part of PEGAG was dissolved in 20 parts of anhydrous THF (5% w / v), then 4 parts of ethyl 2-aminomethacrylate (AEMA) and 0.02 parts of catalyst Sn(Oct)2 (0.1% w / v) were added. The solution was stirred at 25°C for 6 hours under a nitrogen atmosphere, and then 10 parts of diethyl ether were added to precipitate the product. The product was then dried in a vacuum oven for 3 days to obtain the photocurable pre-crosslinked polymer PEGAG-A.

[0037] 2. Dip-and-lift coating:

[0038] One part of PEGAG-A and 0.01 part of 2-hydroxy-2-methyl-1-phenyl-1-propanone (0.05% w / v) were dissolved in 10 parts of deionized water (10% w / v); then, PEGAG-A was coated onto the surface of polypropylene suture (Hainan Baimaike Medical Technology Co., Ltd.) with a specification of 5-0 and a thread diameter of approximately 0.100-0.149 mm (hereinafter the same) by dip-coating and lifting at a lifting speed of 3 cm / min to obtain pre-crosslinked suture.

[0039] 3. Photocuring crosslinking:

[0040] The pre-crosslinked suture obtained above was subjected to 380nm ultraviolet light (~12mWcm). -2 Photopolymerization for 2 minutes, i.e., cross-linking to form a hydrogel on the surface of commercially available ordinary medical vascular sutures, and then drying to obtain a self-expanding medical suture.

[0041] Example 2

[0042] 1. Synthesis of polyethylene glycol-methacrylate prepolymer:

[0043] Under a nitrogen atmosphere of 5 kPa, 1 part of polyethylene glycol with an average molecular weight of 8000 and 2 parts of 2-hydroxypropane-1,2,3-tricarboxylic acid (CA) were dissolved in 20 parts of DMSO (15% w / v), and the mixture was stirred at 900 rpm for 1 h in a water bath at 80 °C. The pressure was then reduced to 3 kPa, and the reaction was continued with stirring for 15 h. After cooling to room temperature, 1 part of N-hydroxysuccinimide (NHS) and 2 parts of 1-ethyl 3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) were added to activate the carboxylic acid groups. After stirring for 2 h, 4 parts of ethyl 2-aminomethacrylate (AEMA) were added, and the mixture was continuously stirred at room temperature for 24 hours. The mixture was then purified by dialysis with deionized water (MWCO: 3500) for 3 days. The purified polymer was then filtered, evaporated, and lyophilized to obtain the photocurable pre-crosslinked polymer PEGC-A.

[0044] 2. Dip-and-lift coating:

[0045] Two parts of PEGC-A and 0.02 parts of 1-hydroxycyclohexylphenyl ketone (0.05% w / v) were dissolved in 10 parts of deionized water (20% w / v); then, PEGC-A was coated onto the surface of the polypropylene suture by dip-coating at a lifting speed of 4 cm / min to obtain a pre-crosslinked suture.

[0046] 3. Photocuring crosslinking:

[0047] The pre-crosslinked sutures obtained above were photopolymerized under 360nm ultraviolet light (~12mWcm-2) for 3 minutes, which crosslinked the sutures on the surface of commercially available ordinary medical vascular sutures to form hydrogels. After drying, self-expanding medical sutures were obtained.

[0048] Example 3

[0049] 1. Synthesis of polyethylene glycol-methacrylate prepolymer:

[0050] Two parts of polyethylene glycol with an average molecular weight of 10,000 and four parts of 5-demethylborene-2-carboxylic acid were dissolved in 20 parts of chloroform (10% w / v), and one part of 4-(dimethylamino)pyridine (DMAP) was added. The solution was heated to 45°C, and 0.4 parts of dibutyl dicarbonate (Boc₂O) were added to the flask using a syringe. After 20 h, cold water was added to quench the reaction. Then, sodium chloride (1 g per 100 mL of solution) was added, and the reactants were precipitated in 10 parts of supercooled (4°C) acetone. The precipitate was filtered and dissolved in 20 parts of deionized water to obtain the PEG-Nor pre-crosslinked polymer, which was stored at 20°C until use.

[0051] 2. Dip-and-lift coating:

[0052] One part of PEG-Nor and 0.01 part of 2-hydroxy-2-methyl-1-(4-methoxy)phenyl-1-propanone (0.05% w / v) were mixed to obtain a coating solution (5% w / v); then, PEG-Nor was coated on the surface of polypropylene sutures by dip-coating at a lifting speed of 15 cm / min to obtain pre-crosslinked sutures.

[0053] 3. Photocuring crosslinking:

[0054] The pre-crosslinked sutures obtained above were photopolymerized under 340nm ultraviolet light (~12mWcm-2) for 4 minutes, which crosslinked the sutures on the surface of commercially available ordinary medical vascular sutures to form hydrogels. After drying, self-expanding medical sutures were obtained.

[0055] Effect test:

[0056] 1. Appearance test of self-expanding medical sutures:

[0057] The scanning electron microscope image of the self-expanding medical suture manufactured according to Example 1 is shown in... Figure 5 In China, self-expanding medical sutures exhibit a porous, cross-linked network structure.

[0058] 2. Study on the swelling properties of hydrogels:

[0059] Five self-expanding medical sutures (each with a needle diameter of 0.24 mm) prepared in Examples 1, 2, and 3 were placed in phosphate-buffered saline (PBS, pH = 7.4) and swollen at 37°C for 20 min. During this period, the diameter of the sutures was measured under a microscope at 0 min, 1 min, 2 min, 5 min, 10 min, 15 min, and 20 min.

[0060] The results are shown in Table 1 below. Figure 6 :

[0061] Table 1. Thread diameter and needle diameter ratio after suture swelling at different observation points.

[0062]

[0063] The self-expanding medical sutures prepared in Examples 1, 2, and 3 generally reach swelling equilibrium after 10 minutes, with a swelling rate of up to 200%, and the needle diameter ratio after swelling equilibrium is close to 1. This indicates that the self-expanding sutures prepared by this method can appropriately swell when the suture comes into contact with liquid, reducing the needle diameter ratio and filling the needle holes left after the suture needle punctures the tissue.

[0064] 3. Bleeding rate test:

[0065] Using expanded polytetrafluoroethylene (ePTFE) artificial blood vessels, a clinical procedure was simulated. After anastomosis sutures were used, the leakage rate of the suture needle holes was measured. A 10cm long ePTFE artificial blood vessel was taken and then installed on the plastic fittings at both ends of the fixation frame and secured with clips. A transverse incision was then made in the middle, followed by anastomosis using polypropylene sutures and self-expanding medical sutures from Example 1. The spacing between each needle hole was approximately 1mm during suturing. All anastomosis procedures were performed by the same surgeon.

[0066] The fabricated vascular anastomosis model was connected to an extracorporeal circulation model to test the bleeding rate during suturing using polypropylene sutures and the self-expanding medical sutures prepared in Example 1. The extracorporeal circulation model consisted of a reservoir for filtering and collecting leaked blood, a computer-integrated data acquisition system, an oxygenator, and a heat exchanger. To simulate clinical conditions, the difference between systolic and diastolic blood pressure was set to 40 mmHg, the pulse pattern to be 120 / 80 mmHg, and the pulse rate to be 72 beats / min. Simulated blood was used in the model. Bleeding rate data were collected within 10 minutes post-suturing using the computer-integrated data acquisition system.

[0067] The bleeding rate results are shown in Table 2 below:

[0068]

[0069] Polypropylene sutures have a high needle hole leakage rate. Data shows that the needle hole leakage rate is greatly reduced after using self-expanding medical sutures, resulting in significant clinical benefits.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a self-expanding medical suture, characterized in that: Includes the following steps: S1. Synthesis of polyethylene glycol-methacrylate prepolymer: Dissolve 0.25-3 parts of polyethylene glycol in 5-30 parts of solvent with a concentration of 5-10% w / v, add a linker under a nitrogen atmosphere of 4-6 kPa, and graft the methacrylate derivative onto the polyethylene glycol backbone to synthesize polyethylene glycol-methacrylate prepolymer. S2, Dip-in Lift Coating: Dissolve 0.25-10 parts of the above-mentioned polyethylene glycol-methacrylate prepolymer and 0.01-3 parts of a photoinitiator with a concentration of 0.05-1% w / v in 5-30 parts of solvent to obtain a coating solution with a concentration of 5-25% w / v; then, apply the prepolymer to the surface of commercially available ordinary medical vascular sutures by dip-coating method at a lifting speed of 1-20 cm / min to obtain a pre-crosslinked suture; S3, Photocuring Crosslinking: The pre-crosslinked suture was applied at 190~380nm and 12mWcm. -2 Photopolymerization under ultraviolet light for 1-5 minutes causes the prepolymer on the suture surface to spontaneously crosslink and form a network structure. After drying, a self-expanding medical suture is obtained. The linker in step S1 includes at least one of succinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 2-hydroxypropane-1,2,3-tricarboxylic acid, 1-hydroxypropane-1,2,3-tricarboxylic acid, 1-propene-1,2,3-tricarboxylic acid, propane-1,2,3-tricarboxylic acid, 2-hydroxybutane-1,2,4-tricarboxylic acid, 1-hydroxybutane-1,2,4-tricarboxylic acid, 1-butene-1,2,4-tricarboxylic acid, and benzene-1,3,5-tricarboxylic acid. When the linker is selected from one or more of succinic acid, adipic acid, pimelic acid, azelaic acid, and sebacic acid, glycerol needs to be added under a nitrogen atmosphere to carry out the reaction.

2. The method for preparing a self-expanding medical suture as described in claim 1, characterized in that: In step S1, the concentration of the polyethylene glycol solution is 5% to 10%.

3. The method for preparing a self-expanding medical suture as described in claim 1, characterized in that: The solvent includes at least one of anhydrous tetrahydrofuran, toluene, chloroform, xylene, and dimethyl sulfoxide.

4. The method for preparing a self-expanding medical suture as described in claim 1, characterized in that: The concentration of the coating solution in step S2 is 5~25% w / v.

5. The method for preparing a self-expanding medical suture as described in claim 1, characterized in that: In step S2, the concentration of the photoinitiator is 0.05~1%w / v.

6. The method for preparing a self-expanding medical suture as described in claim 1, characterized in that: The synthesis of the polyethylene glycol-methacrylate prepolymer in step S1 specifically involves dissolving 0.15 parts of polyethylene glycol with an average molecular weight of 5000 and 0.35 parts of adipic acid in 10 parts of anhydrous tetrahydrofuran at a concentration of 5% w / v under a nitrogen atmosphere at a pressure of 5 kPa. The mixture is stirred at 800 rpm for 1 hour in a 70°C water bath. The pressure is then reduced to 3 kPa, and the reaction is continued with stirring for 15 hours. Next, 3 parts of glycerol are added under a nitrogen atmosphere, and the reaction is continued with stirring for 30 hours. Finally, 10 parts of diethyl ether are added... The product was precipitated and dried at room temperature for 48 hours to obtain PEGAG. One part of PEGAG was dissolved in 20 parts of anhydrous tetrahydrofuran (THF) at a concentration of 5% w / v, and then 4 parts of ethyl 2-aminomethacrylate and 0.02 parts of stannous octoate catalyst at a concentration of 0.1% w / v were added. The solution was stirred at 25°C for 6 hours under a nitrogen atmosphere, and then 10 parts of diethyl ether were added to precipitate the product. The product was then dried in a vacuum oven for 3 days to obtain the photocurable pre-crosslinked polymer PEGAG-A.

7. The method for preparing a self-expanding medical suture as described in claim 1, characterized in that: The method for synthesizing the polyethylene glycol-methacrylate prepolymer in step S1 further includes dissolving 1 part of polyethylene glycol with an average molecular weight of 8000 and 2 parts of 2-hydroxypropane-1,2,3-tricarboxylic acid in 20 parts of dimethyl methacrylate at a concentration of 15% w / v under a nitrogen atmosphere of 5 kPa. The reaction is carried out by stirring at 900 rpm for 1 h in a water bath at 80 °C. The pressure is then reduced to 3 kPa and the reaction is continued by stirring for 15 h. After cooling to room temperature, 1 part of N-hydroxysuccinimide and 2 parts of 1-ethyl 3-(3-dimethylaminopropyl)carbodiimide hydrochloride are added to activate the carboxylic acid groups. After stirring for 2 h, 4 parts of 2-aminomethacrylate are added. After stirring continuously at room temperature for 24 h, the mixture is purified by dialysis with MWCO:3500 deionized water for 3 days. Then, the mixture is filtered, evaporated and lyophilized to obtain the photocurable pre-crosslinked polymer PEGC-A.

8. The method for preparing a self-expanding medical suture as described in claim 1, characterized in that: The step S1, which synthesizes the polyethylene glycol-methacrylate prepolymer, can also be replaced by synthesizing a PEG-Nor precrosslinked polymer. This involves dissolving 2 parts of polyethylene glycol with an average molecular weight of 10,000 Da and 4 parts of 5-norbornene-2-carboxylic acid in 20 parts of chloroform with a concentration of 10% w / v, adding 1 part of 4-(dimethylamino)pyridine, heating the solution to 45°C, adding 0.4 parts of dibutyl dicarbonate to the flask using a syringe, and after 20 hours, adding cold water to quench the reaction, then adding sodium chloride, and precipitating the reactants in 10 parts of acetone supercooled to 4°C. After filtering the precipitate, dissolve it in 20 parts of deionized water to obtain the PEG-Nor precrosslinked polymer, which is stored at 20°C until use.

9. The self-expanding medical suture prepared by the preparation method according to any one of claims 1-3, characterized in that: The self-expanding medical suture has a porous mesh structure and reaches swelling equilibrium after 10 minutes of contact with liquid, with a swelling rate of 200%.

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