PDO-based antibacterial suture and preparation method thereof

Abstract

This invention provides an antibacterial suture based on PDO and its preparation method. The preparation method involves taking polydioxanone (PDO) sutures, performing barbed or herringbone molding to obtain sutures with barbed or herringbone structures on the surface, followed by freeze-setting and plasma surface pretreatment. The plasma-pretreated sutures are then placed in a supercritical reactor with a supercritical CO2-antibacterial agent fluid system to obtain sutures coated with antibacterial agent. This invention overcomes the technical bottlenecks of traditional impregnation, spraying, and steam methods in the preparation of antibacterial coatings. By utilizing the high permeability of supercritical fluids and the synergistic effect of freezing, combined with plasma surface modification and freeze crystallization processes, the adhesion between the antibacterial coating and the PDO substrate is significantly improved, preventing coating peeling during use and extending the antibacterial period. Simultaneously, it achieves uniform coverage of the antibacterial agent on complex structural surfaces such as barbs and herringbone patterns, as well as deep within grooves, ensuring the consistency and stability of product performance.

Description

Technical Field This invention belongs to the field of medical device technology, specifically relating to an antibacterial suture based on PDO and its preparation method. Background Technology PDO (polydioxanone) antibacterial sutures have significant value in clinical applications, and their antibacterial properties mainly depend on the preparation process of the surface antibacterial coating. Currently, the commonly used methods for preparing antibacterial coatings include impregnation and steam methods, but both have significant shortcomings in terms of large-scale production, coating quality, and bonding strength.

[0001] The impregnation method involves immersing PDO sutures in a solution containing an antibacterial agent (such as triclosan), relying on surface tension to allow the coating to adhere to the suture surface. This process has the following drawbacks: First, the production process relies on manual operation, requiring multiple steps such as impregnation, lifting, and drying. The batch processing capacity is limited, typically not exceeding 1000 sutures, and each batch processing cycle is at least 30 minutes, making it difficult to meet the needs of large-scale clinical applications. Second, the PDO suture surface has strong hydrophobicity, and the barbs or herringbone-like structure create a masking effect, resulting in uneven coating thickness distribution. Coating tends to accumulate at the barb tips, while the coating is thinner at the base and in the groove areas due to difficulty in solution penetration, with thickness deviations reaching ±15% or more, leading to batch-to-batch fluctuations in antibacterial performance. Third, the PDO material surface lacks active functional groups, and the coating mainly relies on physical adsorption for adhesion. The adhesion strength is typically less than 0.5 N / cm, making it prone to detachment under the influence of body fluids or tissue traction, resulting in an effective antibacterial period that is difficult to exceed 14 days.

[0002] The steam method involves heating an antibacterial agent to volatilize it into vapor, which then condenses on the PDO seam surface to form a coating. This process has several limitations: First, it requires a sealed, high-pressure environment (pressure not less than 0.5 MPa), resulting in high equipment costs, complex operation, and extremely stringent requirements for packaging sealing. Poor sealing can easily lead to antibacterial agent leakage, affecting the coating's load stability. Second, the steam distribution within the reaction vessel is uneven, with a thicker coating near the heat source and a thinner coating further away. In mass production, the thickness deviation can reach ±20% or more. Furthermore, steam penetration is insufficient in complex structural areas such as barb gaps and herringbone grooves, resulting in a coating coverage rate typically not exceeding 60%. Third, the coating formed by steam condensation only bonds to the PDO surface through van der Waals forces, with an adhesion strength not exceeding 0.4 N / cm, leading to a high risk of detachment and difficulty in achieving long-lasting antibacterial effects.

[0003] In summary, existing coating preparation technologies for PDO antibacterial sutures still have significant technical bottlenecks in terms of production efficiency, coating uniformity, and adhesion. There is an urgent need to develop a new preparation process that can achieve efficient, uniform, and firmly loaded antibacterial coatings. Summary of the Invention The purpose of this invention is to address the shortcomings of existing technologies by providing an antibacterial suture based on PDO and its preparation method. Using PDO suture as the substrate, the invention employs an integrated process of structured molding, freeze-setting, surface modification, functional assembly, supercritical CO2-assisted freeze deposition, and crystallization loading to solve the problems of poor coating adhesion, insufficient uniformity, and low mass production adaptability of existing impregnation and steam methods.

[0004] The present invention adopts the following technical solution: This invention provides a method for preparing PDO-based antibacterial sutures, comprising the following steps: taking polydioxanone sutures and performing barbed or herringbone molding to obtain sutures with barbed or herringbone structures on the surface; freezing and shaping the sutures after molding; performing plasma surface pretreatment on the frozen and shaped sutures; and placing the plasma-pretreated sutures into a supercritical reactor containing a supercritical CO2-antibacterial agent fluid system to obtain sutures coated with antibacterial agents.

[0005] Furthermore, the method for preparing the supercritical CO2-antibacterial agent fluid system in the supercritical reactor is as follows: the antibacterial agent is added to the supercritical reactor with temperature control function, CO2 is introduced, the supercritical reactor is closed and the vacuum is evacuated to a vacuum degree of 0.01 MPa; then the supercritical reactor is heated to the CO2 critical temperature (31.1℃) at a rate of 2~3℃ / min, and pressurized to 7.38~12 MPa at a rate of 2~3 MPa / min, and stirred for 30 min to completely dissolve the antibacterial agent, forming a uniform supercritical CO2-antibacterial agent fluid system.

[0006] Furthermore, the amount of antibacterial agent added is 1-5 wt% of the suture weight; the antibacterial agent is triclosan.

[0007] Furthermore, after the suture is placed in the supercritical reactor, it is placed on a special fixture inside the reactor. The temperature of the supercritical reactor is lowered to -5~0℃ and held for 30 minutes. The purpose is to use the low temperature to further expand the micro-nano pores (formed by plasma pretreatment) on the surface of the suture, while inhibiting the movement of PDO molecular chains to avoid substrate deformation or thermal degradation in subsequent processes. The temperature inside the supercritical reactor is maintained at -5~0℃, and the pressure inside the reactor is 7.38~12 MPa. The suture undergoes periodic dynamic movement in the supercritical reactor for 1.5~2 hours, allowing the supercritical CO2-antibacterial agent fluid system to fully contact the suture. Supercritical CO2 has both the high permeability of a gas and the solubility of a liquid, and can carry triclosan deep into the micro-nano pores and deep barbs and herringbone grooves on the surface of the suture. The penetration depth is significantly improved compared to the immersion method, achieving deep and uniform loading of the antibacterial agent. Subsequently, the temperature of the supercritical reactor is lowered to -10~-15℃, and then the pressure is increased at 0.01~0.1 MPa / min. The pressure is slowly reduced to atmospheric pressure, and the supercritical CO2 instantly turns into gas and escapes. Triclosan rapidly precipitates and deposits in the pores of the wire and on the surface of the structure at low temperature, avoiding the surface agglomeration and masking effect problems of traditional spraying and impregnation methods. Finally, the reactor temperature is maintained at -10~-15℃ for 45~60 minutes to crystallize the deposited triclosan and form a stable crystal structure. This crystal structure forms physical intercalation and weak chemical bonding with the pores and active groups of PDO, significantly improving the adhesion between the coating and the substrate, preventing the loss of antibacterial agent, and allowing the antibacterial agent to adhere to the seam.

[0008] Furthermore, the polydioxanone thread is barbed using a CNC precision barbing machine. The angle of the barbs is 140°~170°, the depth of the barbs is 0.15~0.40 of the thread diameter, and the density of the barbs is 10~20 per cm.

[0009] Furthermore, the polydioxanone wire is formed using a fishbone forming machine, with the angle between the formed fishbone and the wire being 20°~60°, the width being 2~4 times the wire diameter, and the density being 4~12 pieces / cm.

[0010] Furthermore, the cryogenic setting specifically involves placing the formed suture in a low-temperature environment of -50 to -70°C for 1 to 2 hours, followed by a slow temperature increase to room temperature at a rate of 1°C / min. The purpose of cryogenic setting is to rapidly fix the structural morphology at low temperatures, suppress the springback of PDO molecular chains, avoid structural deformation in subsequent processes, and control the dimensional accuracy error of the barbs and herringbone structure within ±0.01mm, while also providing a structural basis for subsequent coating loading.

[0011] Furthermore, the plasma surface pretreatment specifically involves using a low-temperature radio frequency plasma processor (13.56MHz) with an O2 / Ar mixed gas at a volume ratio of 1:2 to 1:4 as the working gas. O2 is used to introduce active groups such as hydroxyl and carboxyl groups onto the material surface, while Ar is used to enhance the surface etching effect. The cryogenically shaped suture is continuously fed through the plasma treatment chamber at a speed of 2–5 mm / s and treated for 30–90 s at a power of 80–150 W. After plasma surface pretreatment, the water contact angle of the suture surface is reduced, and the surface hydrophilicity and density of active groups are increased, thereby enhancing the adhesion between the subsequent antibacterial coating and the substrate.

[0012] Furthermore, after the suture undergoes plasma surface pretreatment, the process includes needle insertion and coil welding. Specifically, an automatic needle insertion machine is used, with a servo motor controlling the crimping force to 0.6~1.0kN, to mechanically crimp the suture needle to one end of the suture. The crimping depth is controlled at 0.2~0.3mm to ensure the connection strength meets requirements. Subsequently, a 20~30 kHz ultrasonic welding machine is used to weld the tail coil at the other end of the suture, setting the welding parameters to power 20~200 W, time 0.5~2 s, and pressure 0.1~0.3 MPa. High-frequency vibration causes localized melting and bonding of the PDO, improving the coil's breaking strength.

[0013] (ii) The present invention also provides an antibacterial suture based on PDO, which is prepared by the preparation method described above.

[0014] The beneficial effects of this invention are: This invention achieves high-precision fixation and surface activation of complex PDO suture structures through the synergistic effect of cryo-setting and plasma pretreatment. Cryo-setting effectively stabilizes the geometric dimensions of microstructures such as barbs and herringbone patterns, preventing deformation during subsequent processing. Plasma pretreatment introduces active groups on the material surface and forms micro- and nano-scale anchoring points, providing the structural foundation and chemical conditions for strong coating adhesion. The synergistic combination of these two techniques fundamentally solves the technical challenges of maintaining structural precision and poor adhesion between the coating and substrate in traditional processes.

[0015] This invention further employs an innovative loading process combining supercritical CO2 and freezing, overcoming the limitations of traditional impregnation and steam methods in terms of coating quality. This process utilizes the high permeability of supercritical fluids, combined with cryogenic deposition and cryo-crystallization, to fully accommodate the heat-sensitive nature of PDO materials and achieve deep, uniform loading of the antibacterial agent into the suture surface and micro / nano pores. Compared to traditional methods, this process significantly improves coating coverage and thickness uniformity, effectively avoiding surface agglomeration and masking effects.

[0016] Furthermore, each process step of this invention is compatible with CNC automated equipment, enabling continuous production throughout the entire process and significantly improving single-batch processing capacity to meet the actual needs of large-scale mass production. Through the comprehensive application of the above-mentioned technical means, the final PDO antibacterial suture is significantly superior to existing technologies in terms of coating adhesion, thickness uniformity, antibacterial durability, and production yield, providing clinical applications with more stable and reliable antibacterial suture products. Attached Figure Description Figure 1 This is a schematic diagram showing the barb angle and depth of the barbed antibacterial suture prepared in Example 1 of the present invention; Figure 2 This is a schematic diagram showing the barb angle and depth of the fishbone antibacterial suture prepared in Example 2 of the present invention; The labels in the attached diagram are: 1. Barb; 2. Fish bone. Detailed Implementation To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0017] Example 1 This invention provides a method for preparing PDO-based antibacterial sutures, the steps of which are as follows: Step 1: Barb Forming Take poly(p-dioxanone) wire (PDO) with a diameter of 0.3 mm (d1=0.3 mm). The PDO wire was fixed at the CNC precision burring machine station. The burring parameters were set as follows: burr angle a1 = 155°, burr depth h1 = 0.08 mm, burr density 15 burrs / cm, feed speed 8 mm / s, and burring pressure 0.5 MPa. After starting the machine, the wire surface was automatically cut and shaped according to the preset program. After the above processing, the burr structure was free of cracks and defects, the dimensional deviation did not exceed 0.02 mm, and the mechanical properties of the wire were retained at a rate of not less than 95%.

[0018] Step 2: Freezing and setting The barbed sutures were placed in an ultra-low temperature freezer and kept at -60℃ for 1.5 hours, then slowly heated to room temperature at a rate of 1℃ / min. After this treatment, the barb structure on the suture surface remained stable, the dimensional accuracy error was controlled within ±0.008mm, and no springback deformation occurred.

[0019] Step 3: Plasma Surface Pretreatment A 13.56MHz radio frequency plasma treatment instrument was used, with an O2 / Ar mixture of 1:3 volume ratio as the working gas and a total gas flow rate of 30 sccm. The cryogenically shaped PDO wire was continuously fed through the plasma treatment chamber at a speed of 3 mm / s and treated for 60 seconds at a power of 120W. After this treatment, the water contact angle on the wire surface decreased from 75° to 31°, and the surface hydroxyl density increased by 48% compared to the untreated state, providing sufficient active sites for the firm adhesion of subsequent coatings.

[0020] Step 4: Assembly of functional components An automated needle-feeding machine, controlled by a servo motor with a crimping force of 0.8 kN, mechanically crimped a 3 / 8 arc, 16 mm long suture needle to one end of the suture. The crimping depth was controlled to 0.25 mm to ensure the needle-suture connection strength met clinical requirements. Subsequently, a tail coil was welded to the other end of the suture using a 25 kHz ultrasonic welding machine, with welding parameters set as follows: power 150 W, welding time 1 s, and pressure 0.2 MPa. The breaking strength of the welded coil met relevant standards.

[0021] Step 5: Applying antibacterial agent to the supercritical reactor The antibacterial agent (triclosan) was added to the supercritical reactor at a rate of 3 wt% of the suture mass. Food-grade CO2 was introduced, and the supercritical reactor was closed and evacuated to a vacuum level of 0.01 MPa. Subsequently, the supercritical reactor was heated to the CO2 critical temperature (31.1 °C) at a rate of 3 °C / min and pressurized to 10 MPa at a rate of 3 MPa / min. The reactor was stirred for 30 min to completely dissolve the antibacterial agent and form a homogeneous supercritical CO2-triclosan fluid system.

[0022] The assembled suture was placed in a fixture inside a supercritical reactor. The temperature of the supercritical reactor was lowered to -5°C and held for 30 minutes. Maintaining the temperature at -5°C and the pressure at 10 MPa, the suture underwent periodic dynamic movement within the reactor for 1.8 hours to ensure full contact between the supercritical CO2-antibacterial agent fluid system and the suture. The temperature of the supercritical reactor was then lowered to -12°C, followed by a depressurization to atmospheric pressure at a rate of 0.05 MPa / min, allowing triclosan to deposit on the surface and within the pores of the suture. Finally, the reactor temperature was maintained at -12°C for 50 minutes for cryogenic crystallization. After this process, triclosan was uniformly deposited on the tip, root, and surface of the barb, with a coating thickness of 10–12 μm and a thickness deviation controlled within ±2 μm (i.e., ≤±3%), and no surface agglomeration occurred.

[0023] Step Six: Automatic Winding and Packaging An automatic winding machine evenly winds the antibacterial sutures into a winding box, which is then sealed in a cleanroom environment. Nitrogen gas is used for protection during packaging, and the sutures are sealed in aluminum foil bags. After this packaging process, the suture surface coating shows no wear, and the product integrity reaches 100%. Final product performance testing results show that the coating adhesion is 1.3 N / cm, the thickness deviation is ±2%, and the 30-day inhibition rate against Staphylococcus aureus is 92%. All indicators meet the clinical requirements for antibacterial sutures used in surgical sutures.

[0024] Example 2 This invention provides a method for preparing PDO-based antibacterial sutures, the steps of which are as follows: Step 1: Fishbone Shaping Take poly(p-dioxanone) wire (PDO), with a diameter of 0.4 mm (d2=0.4 mm) and a molecular weight of 120,000 Da (tensile strength 6.5 N). The fishbone forming machine, equipped with a temperature-controlled double-roller die and an accuracy of ±0.01mm, was used for processing. The forming parameters were set as follows: V-groove angle a2 = 40°, groove width h2 = 1.2mm, groove density 8 grooves / cm, roller temperature 68℃, pressure 0.3MPa, and roller speed 5mm / s. The wire was continuously passed through the double-roller die for forming, and then air-cooled at a cooling rate of 5℃ / s for final shaping. After this process, the fishbone groove structure showed no deformation, with a dimensional deviation not exceeding 0.01mm, and exhibited good structural stability.

[0025] Step 2: Freezing and setting The herringbone-shaped suture was placed in an ultra-low temperature freezer and kept at -70℃ for 2 hours, then slowly heated to room temperature at a rate of 1℃ / min. After the above treatment, the herringbone structure on the surface of the suture remained stable, the dimensional accuracy error was controlled within ±0.009mm, and no springback deformation occurred.

[0026] Step 3: Plasma Surface Pretreatment A 13.56MHz radio frequency plasma processor was used, with an O2 / Ar mixture of 1:3 volume ratio as the working gas and a total gas flow rate of 30 sccm. The cryogenically shaped PDO wire was continuously fed through the plasma processing chamber at a speed of 3 mm / s and processed for 60 seconds at a power of 120W. After this treatment, the water contact angle on the wire surface was 30°, and the density of active groups in the herringbone grooves was 10% higher than that on the surface, which is beneficial for the adhesion of the groove coating.

[0027] Step 4: Assembly of functional components An automated needle-feeding machine, controlled by a servo motor with a crimping force of 0.9 kN, mechanically crimped a 3 / 8 arc, 16 mm long suture needle to one end of the suture. The crimping depth was controlled to 0.25 mm to ensure the needle-suture connection strength met clinical requirements. Subsequently, a tail coil was welded to the other end of the suture using a 25 kHz ultrasonic welding machine, with welding parameters set as follows: power 160 W, welding time 1.2 s, and pressure 0.25 MPa. The breaking strength of the welded coil met relevant standards.

[0028] Step 5: Applying antibacterial agent to the supercritical reactor The antibacterial agent (triclosan) was added to the supercritical reactor at a rate of 5 wt% of the suture mass. Food-grade CO2 was introduced, and the supercritical reactor was closed and evacuated to a vacuum level of 0.01 MPa. Subsequently, the supercritical reactor was heated to the CO2 critical temperature (31.1 °C) at a rate of 3 °C / min and pressurized to 12 MPa at a rate of 3 MPa / min. The reactor was stirred for 30 min to completely dissolve the antibacterial agent and form a homogeneous supercritical CO2-triclosan fluid system.

[0029] The assembled suture was placed in a fixture inside a supercritical reactor. The temperature of the supercritical reactor was lowered to 0°C and held for 30 minutes. Maintaining the temperature inside the supercritical reactor at 0°C and the pressure at 12 MPa, the suture underwent periodic dynamic movement within the reactor for 2 hours to ensure full contact between the supercritical CO2-antibacterial agent fluid system and the suture. The temperature of the supercritical reactor was then lowered to -15°C, followed by a depressurization to atmospheric pressure at a rate of 0.1 MPa / min, allowing triclosan to deposit on the surface and within the pores of the suture. Finally, the reactor temperature was maintained at -15°C for 60 minutes for cryogenic crystallization. After this process, the coating completely filled the fishbone grooves (99% fill rate), with a coating thickness of 12-14 μm on both the surface and within the grooves, and a total deviation of ±2.5 μm (≤±3%).

[0030] Step Six: Automatic Winding and Packaging An automatic winding machine evenly winds the antibacterial sutures into a winding box, which is then sealed in a cleanroom environment. Nitrogen gas is used for protection during packaging, and the sutures are sealed in aluminum foil bags. After this packaging process, the suture surface coating shows no wear, and the product qualification rate reaches 100%. Final product performance testing results show that the coating adhesion is 1.4 N / cm, the thickness deviation is ±2.3%, the 30-day antibacterial rate is 93%, and the herringbone structure provides 23% better tissue holding power than ordinary sutures, making it suitable for deep tissue suturing.

[0031] This invention introduces active groups onto a PDO substrate through plasma surface pretreatment. Combined with the deep penetration of supercritical CO2-assisted cryogenic deposition and the physical interlocking effect of cryo-crystallization, a dual mechanism of chemical bonding and physical anchoring is established between the coating and the substrate. This overcomes the problem of coating detachment caused by traditional processes relying solely on physical adsorption. The resulting antibacterial sutures maintain stable coating adhesion even under conditions of bodily fluid flushing and tissue traction, and the antibacterial period covers the critical infection control phase of wound healing, meeting the clinical need for long-lasting antibacterial function.

[0032] This invention utilizes the high permeability of supercritical fluids to ensure that antibacterial agents are uniformly loaded onto complex structural areas such as the tips, roots, and grooves of barbs, effectively solving the coating thickness deviation problems caused by shielding effects or uneven steam distribution in traditional impregnation and steam methods. By adjusting the amount of antibacterial agent and the treatment time, the coating thickness can be precisely controlled according to clinical needs, enabling differentiated drug loading designs for different infection risk scenarios. This significantly improves batch-to-batch performance consistency, greatly increases production yield, and is more suitable for the quality control requirements of large-scale production.

[0033] The supercritical CO2-assisted cryodeposition and crystallization loading processes employed in this invention are completed entirely at low temperatures, avoiding the risk of thermal degradation of PDO materials caused by high-temperature steam treatment and ensuring the excellent preservation of the suture's mechanical properties. Simultaneously, the application of cryo-setting technology significantly improves the dimensional accuracy and structural stability of microstructures such as barbs and herringbone patterns, maintaining good tissue holding force during suturing and tissue healing, thus providing reliable assurance for clinical procedures and postoperative outcomes.

[0034] Each process step of this invention is compatible with CNC automated equipment, enabling continuous production from structural forming to finished product packaging. The single-batch processing capacity is significantly improved compared to the traditional impregnation method, effectively meeting the needs of large-scale clinical applications. Supercritical CO2 is recyclable, resulting in high raw material utilization. Furthermore, processes such as plasma treatment and ultrasonic welding reduce manual intervention, effectively controlling overall production costs. Automated winding and nitrogen-filled sealing packaging further avoid coating wear that may be caused by manual operation, extending the product's storage stability and laying a solid foundation for commercialization.

[0035] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions that fall within the scope of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an antibacterial suture based on PDO, characterized in that, Includes the following steps: Take polydioxanone wire and perform barbed or herringbone molding to obtain a suture with a barbed or herringbone structure on the surface. The sutures are then frozen to set their shape. Plasma surface pretreatment is performed on the sutures after freeze-setting; The sutures, after plasma surface pretreatment, were placed into a supercritical reactor containing a supercritical CO2-antibacterial agent fluid system to obtain sutures coated with antibacterial agent.

2. The method for preparing PDO-based antibacterial sutures according to claim 1, characterized in that, The method for preparing the supercritical CO2-antibacterial agent fluid system in the supercritical reactor is as follows: The antibacterial agent was added to the supercritical reactor, CO2 was introduced, and the supercritical reactor was closed and evacuated. Then the supercritical reactor was heated to the CO2 critical temperature at a rate of 2~3℃ / min and pressurized to 7.38~12Mpa at a rate of 2~3MPa / min. The reactor was stirred to completely dissolve the antibacterial agent and form a uniform supercritical CO2-antibacterial agent fluid system.

3. The method for preparing PDO-based antibacterial sutures according to claim 2, characterized in that, The amount of the antibacterial agent added is 1-5 wt% of the suture weight; The antibacterial agent is triclosan.

4. The method for preparing PDO-based antibacterial sutures according to claim 1, characterized in that, After the suture is placed into the supercritical reactor, the temperature of the supercritical reactor is lowered to -5~0℃ and kept at that temperature for 30 minutes. Maintain the temperature inside the supercritical reactor at -5~0℃ and the pressure inside the reactor at 7.38~12Mpa. Allow the suture to undergo periodic dynamic movement inside the supercritical reactor for 1.5~2 hours to ensure that the supercritical CO2-antibacterial agent fluid system is in full contact with the suture. The temperature of the supercritical reactor is lowered to -10~-15℃, and then the pressure is reduced to atmospheric pressure at a rate of 0.01~0.1MPa / min. The reactor temperature is maintained at -10~-15℃ for 45~60 minutes to allow the antibacterial agent to adhere to the suture.

5. The method for preparing PDO-based antibacterial sutures according to claim 1, characterized in that, The polydioxanone filament is barbed using a CNC precision barbing machine. The barb angle is 140°~170°, the barb depth is 0.15~0.40 of the filament diameter, and the barb density is 10~20 filaments / cm.

6. The method for preparing PDO-based antibacterial sutures according to claim 1, characterized in that, The polydioxanone wire is formed using a fishbone forming machine. The angle between the formed fishbone and the wire is 20°~60°, the width is 2~4 times the wire diameter, and the density is 4~12 pieces / cm.

7. The method for preparing PDO-based antibacterial sutures according to claim 1, characterized in that, The cryopreservation process specifically involves: The formed suture is kept in a low temperature environment of -50~-70℃ for 1~2 hours, and then slowly heated to room temperature at a rate of 1℃ / min.

8. The method for preparing PDO-based antibacterial sutures according to claim 1, characterized in that, The plasma surface pretreatment specifically includes: A low-temperature radio frequency plasma treatment instrument was used, with an O2 / Ar mixed gas with a volume ratio of 1:2 to 1:4 as the working gas. The frozen and shaped sutures were continuously transported through the plasma treatment chamber at a speed of 2 to 5 mm / s and treated for 30 to 90 s under a power of 80 to 150 W.

9. The method for preparing PDO-based antibacterial sutures according to claim 1, characterized in that, After the suture undergoes plasma surface pretreatment, the process also includes welding the needle to the coil, specifically: An automatic needle-feeding machine is used, with a servo motor controlling the crimping force to 0.6~1.0kN, to mechanically crimp the suture needle to one end of the suture, with the crimping depth controlled to 0.2~0.3 mm; then, a 20~30 kHz ultrasonic welding machine is used to weld the tail coil at the other end of the suture, with the welding parameters set as follows: power 20~200 W, time 0.5~2 s, and pressure 0.1~0.3 MPa.

10. The antibacterial suture prepared by the preparation method according to any one of claims 1 to 9.

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