Preparation method of PPDO composite material and preparation method of absorbable suture line with barbs

Abstract

The invention discloses a preparation method of a PPDO composite material and an absorbable suture line with barbs, and belongs to the technical field of medical biomaterials.Silica-based Janus particles are prepared through a one-pot method and serve as active interfaces after being coated with polydopamine, ZIF-8 crystal shells are guided to grow in situ, epigallocatechin gallate is synchronously encapsulated, and the absorbable suture line with the barbs is prepared. The preparation method comprises the following steps: preparing antibacterial composite particles, compounding the antibacterial composite particles, poly (p-dioxanone), polylactic acid, quinazarin and acetyl tributyl citrate through a melt blending process to obtain a PPDO composite material, carrying out melt spinning and stretching heat setting on the PPDO composite material to prepare the antibacterial absorbable suture line, and carrying out mechanical cutting and eversion process processing to obtain the antibacterial absorbable suture line. The absorbable suture line with the barbs, which has excellent mechanical strength and long-acting antibacterial property, is obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of medical biomaterials, and particularly relates to a PPDO composite material and a preparation method of absorbable suture with barbs. BACKGROUND

[0002] Absorbable suture is a kind of medical material suitable for the healing rule of human body tissue. After implantation, it is gradually degraded into carbon dioxide, water or amino acid and other harmless substances through enzymatic or hydrolysis reaction, and is finally completely absorbed by the human body, without the need for postoperative suture removal, and is widely used in surgery, obstetrics and gynecology, plastic surgery and the like.

[0003] However, the ordinary absorbable suture has low initial tensile strength, and the strength will decrease after several days of degradation, so it cannot support tissues with high tension such as skin and tendon. Although the strength of the synthetic material is improved, the degradation period does not match the tissue healing speed, which easily leads to premature rupture or long-term foreign body retention. The new absorbable suture, such as poly-p-dioxanone (PPDO), is an aliphatic polyester material with excellent biocompatibility, bioabsorbability and biodegradability. The mechanical properties and degradation rate can be precisely balanced through molecular structure regulation, so that the suture can maintain sufficient tensile strength while ensuring synchronous degradation after complete tissue healing, thereby significantly improving the clinical applicability and safety.

[0004] A Chinese patent application with the publication number CN116410448A discloses a poly-p-dioxanone and a preparation method and application thereof. In the application, p-dioxanone, a stabilizer and a catalyst are mixed to obtain a uniform activation mixture through activation treatment, and then the activation mixture is subjected to a polymerization reaction under a protective gas to obtain poly-p-dioxanone. The poly-p-dioxanone is used as a raw material to prepare a suture.

[0005] However, the suture prepared by using pure poly-p-dioxanone as a raw material is difficult to withstand the huge tensile force of bones and tendons or the continuous pulsatile stress of the cardiovascular system for a long time, and has a risk of rupture, which forces the patient to undergo a second surgery, and in severe cases, endangers the patient's life. SUMMARY

[0006] The purpose of the present application is to provide a PPDO composite material and a preparation method of absorbable suture with barbs. A silica-based Janus particle is used as a structural reinforcement core, and then polydopamine is coated and loaded with ZIF-8 and a synergistic antibacterial agent to obtain an antibacterial composite particle. When the antibacterial composite particle is applied to a PPDO / PLA composite material, the composite material not only maintains excellent mechanical properties and processing stability, but also has long-term antibacterial function. Finally, a suture with high strength and bioabsorbability is obtained through a melt spinning and mechanical cutting eversion process.

[0007] The purpose of the present application can be achieved by the following technical solutions:

[0008] A PPDO composite material comprising the following raw materials in parts by mass:

[0009] Poly-p-dioxanone 48-54 parts, polylactic acid 24 parts, antibacterial composite particles 2-3 parts, quinizarin 0.1-0.2 parts, and acetyl tri-butyl citrate 5 parts.

[0010] Further, the antibacterial composite particles are prepared by the following steps:

[0011] Step one: by one-pot method, hydrolysis and condensation of tetraethyl orthosilicate to form a silica inorganic framework, followed by free radical polymerization to graft polystyrene chains in sequence and secondary polymerization to obtain silica-based Janus particles;

[0012] Step two: coating the silica-based Janus particles with polydopamine by dopamine oxidation self-polymerization, obtaining polydopamine-coated Janus microparticles; then chelating zinc ions with this layer, and coordinating with 2-methyl imidazole to self-assemble on the surface of the microparticles to grow a ZIF-8 crystal shell, and coating epigallocatechin gallate in it to obtain antibacterial composite particles.

[0013] Further, the silica-based Janus particles are prepared by the following steps:

[0014] The surfactant and deionized water are added to the reaction kettle, stirred and dissolved, then tetraethyl orthosilicate, (3-mercaptopropyl) trimethoxysilane, and n-hexadecane are added, stirred at 100-200 rpm for 20-30 min, the pH value is adjusted to 9 with sodium hydroxide, and reacted at 60-70°C for 4-5 h. Then, under nitrogen protection, styrene and 2,2-azobisisobutyronitrile are added dropwise, stirred and dispersed at 100-200 rpm for 4-5 h, polymerized at 70-80°C for 12-14 h, then a methyl methacrylate mixture is added dropwise under nitrogen protection, reacted at 70-80°C for 16-18 h, centrifuged and filtered, washed, and vacuum dried to constant weight to obtain silica-based Janus particles.

[0015] Further, the amount ratio of the surfactant, deionized water, tetraethyl orthosilicate, (3-mercaptopropyl) trimethoxysilane, n-hexadecane, styrene, 2,2-azobisisobutyronitrile, and methyl methacrylate mixture is 0.03-0.05 g: 200-300 mL: 10-15 g: 2.6-3.2 g: 2-2.6 g: 20-26 g: 0.05-0.1 g: 11.28-16.48 g.

[0016] Further, the surfactant is any one of cetyltrimethylammonium bromide or sodium dodecyl sulfate.

[0017] Further, the methyl methacrylate mixed solution is obtained by mixing methyl methacrylate, styrene and 2,2-azobisisobutyronitrile according to a mass ratio of 30-48:15-22:0.1-0.2.

[0018] Further, the polydopamine-coated Janus microparticles are prepared by the following steps:

[0019] The silica-based Janus particles are added into deionized water, ultrasonically dispersed, and then the pH value is adjusted to 8.5 by sodium hydroxide, and then dopamine hydrochloride powder and anhydrous ethanol are added, and the mixture is stirred at 500-600 rpm for 24-26 h, and then the product is centrifuged and filtered, and the precipitate is washed and vacuum dried to constant weight to obtain the polydopamine-coated Janus microparticles.

[0020] Further, the silica-based Janus particles, deionized water, dopamine hydrochloride powder and anhydrous ethanol are used in a ratio of 3-5 g:500-600 mL:0.4-0.6 g:250-300 mL.

[0021] Further, the antibacterial composite particles are prepared by the following steps:

[0022] The polydopamine-coated Janus microparticles, zinc salt and deionized water are added into a reaction kettle, and after the zinc nitrate hexahydrate is completely dissolved, the mixture is ultrasonically dispersed for 10-20 min, and then 2-methylimidazole and epigallocatechin gallate are dissolved in methanol and added into the reaction kettle, and the mixture is stirred for 1-2 min, and then centrifuged at 8000-9000 rpm for 20-30 min, and then filtered, and the filter cake is washed with methanol for 3-5 times, and then freeze-dried for 48-50 h to obtain the antibacterial composite particles.

[0023] Further, the polydopamine-coated Janus microparticles, zinc salt, deionized water, 2-methylimidazole, epigallocatechin gallate and methanol are used in a ratio of 0.8-1.2 g:4.2-5.2 g:140-200 mL:9.24-12.14 g:140-200 mg:280-350 mL.

[0024] Further, the zinc salt is any one of zinc acetate, zinc chloride and zinc nitrate hexahydrate.

[0025] Further, the PPDO composite material is prepared by the following steps:

[0026] The poly-p-dioxanone, polylactic acid, antibacterial composite particles, alizarin and acetyl tri-butyl citrate are added into a reaction kettle, and the mixture is stirred for 10-20 min, and then vacuumed for 10-20 min at room temperature, and then the system is heated to 140-150℃ and kept at a constant temperature for melt blending for 10-20 min under the protection of nitrogen atmosphere to obtain the PPDO composite material.

[0027] Furthermore, the ratio of poly(p-dioxanone), polylactic acid, antibacterial composite particles, quinone zirconia, and tributyl acetyl citrate is 48-54g: 24g: 2-3g: 0.1-0.2g: 5g.

[0028] The present invention also provides a method for preparing a barbed absorbable suture, comprising the following steps:

[0029] The above-mentioned PPDO composite material was melt-spun at 145℃ and 1.1MPa nitrogen pressure. The nascent fibers were quenched in an ice-water bath for 5 minutes and then stretched and oriented 6 times at room temperature. After heat setting at 70℃ for 6 hours, an antibacterial absorbable suture was obtained and installed on a winding machine. The forward button was pressed to start moving forward. The cutter cutting angle was set to 160°, the relative cutting depth to 20%, and the barb spacing to 1mm. Mechanical cutting was performed in a spiral arrangement. During the cutting process, an outward turning process was applied simultaneously. When the cutter returned, it moved upward by 0.01mm to turn the bottom of the barb outward at an outward turning angle of 170°, resulting in a barbed absorbable suture.

[0030] The beneficial effects of this invention are:

[0031] 1. This invention constructs a multi-level functional structure of "silica Janus core - polydopamine interlayer - ZIF-8 antibacterial shell", integrating inorganic reinforcement, interfacial compatibility and antibacterial ability in PPDO composite material. The silica-based Janus particles achieve efficient enhancement of mechanical properties through anisotropic structure, the polydopamine layer plays a dual role of interfacial adhesion and metal ion chelation, and the ZIF-8 shell achieves antibacterial release to the infection microenvironment by encapsulating the natural antibacterial agent EGCG. Finally, by combining melt spinning and mechanical outward turning processes, a barbed absorbable suture with excellent mechanical strength, long-lasting antibacterial effect and reliable tissue fixation is prepared.

[0032] 2. The silica-based Janus particles in this invention, as highly efficient nano-reinforcers, significantly improve the interfacial compatibility and bonding force with the polymer matrix through asymmetric surface chemistry, thereby enhancing the mechanical strength and toughness of the material. They also provide conditions for subsequent polydopamine coating and in-situ growth of the ZIF-8 antibacterial shell, forming the core foundation for achieving the "structural reinforcement-synergistic antibacterial" function. At the same time, their uniform dispersion in the matrix effectively ensures the stability of the composite material during processing and the consistency of the finished product.

[0033] 3. The polydopamine-coated Janus microparticles in this invention coat the surface of silica-based Janus particles with polydopamine. As a strong "molecular bridge," polydopamine significantly enhances the interfacial bonding force between the particles and the polymer matrix through its universal adhesion properties, effectively improving the mechanical properties of the material. Furthermore, it utilizes the abundant functional groups on the surface to precisely chelate zinc ions, laying the foundation for the heterogeneous nucleation and directional growth of the ZIF-8 shell, and synergistically enhancing the stability of the entire antibacterial system.

[0034] 4. The antibacterial composite particles of this invention construct a core-shell structure of "ZIF-8 metal-organic framework shell encapsulating natural antibacterial agent EGCG". On the one hand, it utilizes the dissociable properties of ZIF-8 in a weakly acidic infection microenvironment to achieve synergistic drug release of EGCG and zinc ions, providing long-lasting and precise antibacterial effects. On the other hand, through the in-situ encapsulation effect of ZIF-8 channels, it effectively protects the activity of heat-sensitive EGCG during processing. At the same time, its bottom layer of polydopamine-modified Janus structure ensures a firm bond between the particles and the polymer matrix. While endowing the material with strong antibacterial function, it synergistically enhances the overall mechanical properties and structural stability, ultimately achieving a unity of high antibacterial efficiency, long-lasting effect, and material enhancement. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments in the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1: This example provides a barbed absorbable suture, which is prepared by the following method:

[0037] S1: Add 0.03g sodium dodecyl sulfate and 200mL deionized water to a reaction vessel and stir to dissolve. Then add 10g tetraethyl orthosilicate, 2.6g (3-mercaptopropyl)trimethoxysilane and 2g n-hexadecane. Stir mechanically at 100rpm for 20min. Adjust the pH to 9 with sodium hydroxide and react at 60℃ for 4h. Cool to room temperature and add 20g styrene and 0.05g 2,2-azobisisobutyronitrile dropwise under nitrogen protection. After stirring and dispersing at 100rpm for 4h, polymerize at 70℃ for 12h. Then add 11.28g methyl methacrylate mixture dropwise under nitrogen protection and react at 70℃ for 16h. Centrifuge and filter. Wash the precipitate three times alternately with ethanol and deionized water and vacuum dry for 20min to obtain silica-based Janus particles with an average particle size of 520nm.

[0038] The methyl methacrylate mixture is obtained by mixing methyl methacrylate, styrene, and 2,2-azobisisobutyronitrile in a mass ratio of 30:15:0.1.

[0039] A one-pot method is used to form a silica inorganic framework by hydrolysis and condensation of tetraethyl orthosilicate. Polystyrene chains are first covalently grafted onto the inorganic framework through free radical polymerization. Then, a second polymerization is carried out by adding methyl methacrylate and styrene to obtain core-shell structured silica-based Janus particles.

[0040] S2: Add 3g of silica-based Janus particles to 500mL of deionized water, disperse by ultrasonication, adjust the pH to 8.5 with sodium hydroxide, add 0.4g of dopamine hydrochloride powder and 250mL of anhydrous ethanol, stir at 500rpm for 24h, centrifuge and filter the product, wash the precipitate three times with anhydrous ethanol, and vacuum dry for 30min to obtain polydopamine-coated Janus microparticles.

[0041] By utilizing the oxidative self-polymerization of dopamine under weakly alkaline conditions, a 15 nm thick polydopamine adhesive layer with amino groups was constructed on the surface of silica-based Janus particles.

[0042] S3: Add 0.8g of polydopamine-coated Janus microparticles, 4.2g of zinc nitrate hexahydrate and 140mL of deionized water to the reaction vessel. Stir until the zinc nitrate hexahydrate is completely dissolved and then ultrasonically disperse for 10min. Then, dissolve 9.24g of 2-methylimidazole and 140mg of epigallocatechin gallate in 280mL of methanol and add it to the reaction vessel. Stir for 1min, centrifuge at 8000rpm for 20min, filter, wash the filter cake three times with methanol, and freeze-dry for 48h to obtain antibacterial composite particles with an average particle size of 680nm.

[0043] The abundant functional groups on the surface of the polydopamine layer can pre-chelate zinc ions, which then coordinate with 2-methylimidazole to self-assemble, forming heterogeneous nucleation and growth on the surface of the microparticles to form the ZIF-8 crystal shell. At the same time, epigallocatechin gallate, with its phenolic hydroxyl group and conjugated aromatic ring structure, is in situ encapsulated in the pores or interfaces of ZIF-8 through π-π stacking and hydrogen bonding.

[0044] S4: Add 48g of poly(p-dioxanone), 24g of polylactic acid, 2g of antibacterial composite particles, 0.1g of quinone zirconia and 5g of acetylated tributyl citrate to a reaction vessel, stir for 10min, vacuum at room temperature for 10min, and heat the system to 140℃ under nitrogen atmosphere protection and melt-blend at a constant temperature for 10min to obtain PPDO composite material.

[0045] S5: Transfer the PPDO composite material to the reactor barrel, install a 1.00mm diameter spinneret, and melt spin spin at 145℃ and 1.1MPa nitrogen pressure. After the nascent fibers are rapidly cooled in an ice-water bath for 5 minutes, they are stretched and oriented 6 times at room temperature and heat-set at 70℃ for 6 hours to obtain antibacterial absorbable sutures. Install the antibacterial absorbable sutures on a winding machine, press the forward button to start moving forward, set the cutter cutting angle to 160°, the relative cutting depth to 20%, and the barb spacing to 1mm, and perform mechanical cutting in a spiral arrangement (density 7 barbs / circumference). During the cutting process, apply an outward turning process simultaneously. When the cutter returns, it moves upward by 0.01mm to turn the bottom of the barbs outward at an outward turning angle of 170° to obtain barbed absorbable sutures.

[0046] Example 2: This example provides a barbed absorbable suture. The difference from Example 1 is that in step S1, hexadecyltrimethylammonium bromide is used instead of sodium dodecyl sulfate to prepare PPDO composite material and barbed absorbable suture.

[0047] Example 3: This example provides a barbed absorbable suture, which differs from Example 1 in that the ratio of sodium dodecyl sulfate, deionized water, tetraethyl orthosilicate, (3-mercaptopropyl)trimethoxysilane, n-hexadecane, styrene, 2,2-azobisisobutyronitrile, and methyl methacrylate mixture in step S1 is 0.05g:300mL:15g:3.2g:2.6g:26g:0.1g:16.48g.

[0048] Example 4: This example provides a barbed absorbable suture, which differs from Example 1 in that the ratio of silica-based Janus particles, deionized water, dopamine hydrochloride powder and anhydrous ethanol in step S2 is 5g:600mL:0.6g:300mL.

[0049] Example 5: This example provides a barbed absorbable suture. The difference from Example 1 is that zinc acetate and zinc chloride are used instead of zinc nitrate hexahydrate in step S3 to prepare PPDO composite material and barbed absorbable suture.

[0050] Example 6: This example provides a barbed absorbable suture, which differs from Example 1 in that the ratio of polydopamine-coated Janus microparticles, zinc nitrate hexahydrate, deionized water, 2-methylimidazole, epigallocatechin gallate, and methanol in step S3 is 1.2g:5.2g:200mL:12.14g:200mg:350mL.

[0051] The barbed absorbable sutures prepared in Examples 1-6 of this application were sterilized using ethylene oxide at a concentration of 250 mg / L for 4 hours. The sterilized sutures can be used for wound closure. Poly(p-dioxanone) was selected from Wuhan Shuer Biotechnology Co., Ltd., brand name Shuer, model name whshuer; polylactic acid was selected from Suzhou Chuangyuxuan Plastic Raw Materials Co., Ltd., brand name Total, grade name LX530; the remaining raw materials were commercially available products.

[0052] Comparative Example 1: The difference from Example 1 is that n-hexadecane is not added in step S1, while the other steps remain unchanged, and PPDO composite material and barbed absorbable suture are prepared.

[0053] Comparative Example 2: The difference from Example 1 is that step S2 is omitted and in step S3, polydopamine-coated Janus microparticles are replaced with silica-based Janus particles. The remaining steps remain unchanged, and PPDO composite material and barbed absorbable sutures are prepared.

[0054] Comparative Example 3: The difference from Example 1 is that zinc nitrate hexahydrate is not added in step S3, while the other steps remain unchanged, and PPDO composite material and barbed absorbable suture are prepared.

[0055] The barbed absorbable sutures prepared in Examples 1-6 and Comparative Examples 1-3 were cut into 10cm pieces for sampling, and mechanical and antibacterial tests were performed. The specific test methods are as follows:

[0056] Mechanical properties: Referring to GB / T3916-2013 "Determination of breaking strength and elongation at break of single yarn in packaged textiles", a single yarn electronic tensile tester was used, with the tensile rate set to 20 mm / min, to test the breaking strength and elongation at break of the sample.

[0057] Antibacterial performance: Referencing GB / T20944.1-2007 "Evaluation of Antimicrobial Properties of Textiles - Part 1: Agar Diffusion Method", the bacterial strains used were Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. The experimental method involved inoculating approximately 1 mL of bacterial suspension (1 × 10⁸ CFU / mL) onto an agar plate and incubating it at 37°C for 120 h. If the inhibitory concentration was reached, no microbial growth would occur, and a clear inhibitory area would appear around the circular sample. At least three measurements were taken for each sample, and the average value was used as the test result.

[0058] The results are shown in Table 1:

[0059] Table 1 Performance Test Results of Barbed Absorbable Sutures

[0060] Item Example 1 Example 2 Example 3 Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Breaking strength / N 160.8 157.6 158.3 159.2 158.2 158.7 133.6 145.3 156.7 Breaking elongation / % 55.2 52.3 54.1 55.0 53.2 53.9 48.3 51.8 52.1 Bacteriostatic rate against E. coli 99.9 99.8 99.7 99.7 99.8 99.6 88.3 67.8 16.2 Bacteriostatic rate against S. aureus 99.9 99.6 99.2 99.7 99.3 99.6 86.2 65.3 17.5

[0061] As shown in Table 1, the barbed absorbable sutures prepared in Examples 1-6 are significantly superior to those in Comparative Examples 1-3. These examples utilize silica-based Janus particles as the structural core, followed by polydopamine coating to construct an intermediate layer with both strong adhesion and abundant functional groups. This functional layer pre-chelates zinc ions, allowing for heterogeneous nucleation and growth of ZIF-8 crystal shells on the particle surface. Simultaneously, the natural antibacterial agent epigallocatechin gallate is in situ coated into its pores or interfaces, ultimately yielding antibacterial composite particles. These particles, melt-blended with matrix materials such as poly(p-dioxanone) and polylactic acid, collectively endow the PPDO composite material with excellent mechanical strength, long-lasting antibacterial properties, and enhanced processing stability.

[0062] The significant decrease in fracture strength and elongation at break in Comparative Example 1 is likely due to the absence of hexadecane, which prevents the formation of silica-based Janus particles with an asymmetric structure. Hexadecane acts as a crucial phase separation inducer in this process, forcing the hydrophobic monomer and silane coupling agent to align and react by forming oil-phase microregions in the reaction system. This is essential for achieving the core-shell anisotropic structure (Janus characteristics). Without this component, only ordinary composite particles with uniform surface chemistry are generated. These particles, acting as a reinforcing phase, exhibit poor interfacial compatibility and weak anchoring effect in the polymer matrix. This not only significantly reduces stress transfer efficiency, making the material prone to crack initiation and rapid propagation under stress, but also indirectly affects the uniformity of subsequent functionalization modifications, thus collectively leading to a significant deterioration in mechanical properties.

[0063] In Comparative Example 3, the inhibition rates of Escherichia coli and Staphylococcus aureus were significantly reduced, which may be due to...

[0064] The absence of zinc nitrate hexahydrate prevented the construction of the ZIF-8 metal-organic framework functional shell. The lack of zinc ions prevented ZIF-8 from coordinating and self-assembling with 2-methylimidazole, resulting not only in the loss of ZIF-8's own slow-release zinc ion antibacterial ability, but more importantly, depriving the natural antibacterial agent EGCG of its porous carrier and protective shell. This prevented effective loading, in-situ encapsulation, and synergistic release within the infection microenvironment, ultimately leading to the complete destruction of its antibacterial mechanism and performance degradation.

[0065] In Comparative Example 2, the fracture strength, elongation at break, antibacterial rate against *E. coli*, and antibacterial rate against *Staphylococcus aureus* all decreased, possibly due to the absence of a polydopamine coating layer, which disrupted the crucial bridge between structural reinforcement and antibacterial function. The polydopamine coating layer not only enhances the interfacial bonding between Janus particles and the polymer matrix with its excellent adhesion, thereby improving mechanical properties, but more importantly, its abundant surface functional groups are the only guarantee for the pre- and efficient chelation of zinc ions. The absence of this step prevents subsequent effective heterogeneous nucleation on the particle surface and the growth of a complete and robust ZIF-8 antibacterial shell. Therefore, the absence of ZIF-8 directly causes a sharp drop in antibacterial ability, while the absence of the polydopamine coating layer leads to the dual failure of interfacial bonding and antibacterial function, ultimately resulting in a simultaneous decline in mechanical properties and antibacterial rate.

[0066] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A PPDO composite material, characterized in that, The following raw materials are included by weight: 48-54 parts of polydioxanone, 24 parts of polylactic acid, 2-3 parts of antibacterial composite particles, 0.1-0.2 parts of quinone zirconia, and 5 parts of tributyl acetylacetonate; The antibacterial composite particles are prepared through the following steps: Step 1: Tetraethyl orthosilicate is hydrolyzed and condensed to form a silica inorganic framework using a one-pot method. Subsequently, polystyrene chains are grafted onto the framework via free radical polymerization and a secondary polymerization is carried out to obtain silica-based Janus particles. Step 2: Dopamine is oxidatively polymerized to coat the surface of silica-based Janus particles, resulting in polydopamine-coated Janus microparticles. Then, this layer is used to chelate zinc ions, which coordinate with 2-methylimidazole to form a self-assembly, growing a ZIF-8 crystal shell on the surface of the microparticles. Epigallocatechin gallate is then coated into the shell to obtain antibacterial composite particles.

2. The PPDO composite material according to claim 1, characterized in that, The specific preparation method of the silica-based Janus particles is as follows: Surfactant and deionized water were added to a reaction vessel and stirred to dissolve. Then tetraethyl orthosilicate, (3-mercaptopropyl)trimethoxysilane and n-hexadecane were added and stirred at 100-200 rpm for 20-30 min. The pH was adjusted to 9 with sodium hydroxide and the reaction was carried out at 60-70℃ for 4-5 h. After cooling, styrene and 2,2-azobisisobutyronitrile were added dropwise under nitrogen protection and dispersed by stirring at 100-200 rpm for 4-5 h. Polymerization was carried out at 70-80℃ for 12-14 h. Then, a mixture of methyl methacrylate was added dropwise under nitrogen protection and the reaction was carried out at 70-80℃ for 16-18 h. After centrifugation and filtration, the mixture was washed and vacuum dried to constant weight to obtain silica-based Janus particles.

3. The PPDO composite material according to claim 2, characterized in that, The ratio of the surfactant, deionized water, tetraethyl orthosilicate, (3-mercaptopropyl)trimethoxysilane, n-hexadecane, styrene, 2,2-azobisisobutyronitrile, and methyl methacrylate mixture is 0.03-0.05g: 200-300mL: 10-15g: 2.6-3.2g: 2-2.6g: 20-26g: 0.05-0.1g: 11.28-16.48g.

4. The PPDO composite material according to claim 3, characterized in that, The surfactant is either cetyltrimethylammonium bromide or sodium dodecyl sulfate; The methyl methacrylate mixture is obtained by mixing methyl methacrylate, styrene, and 2,2-azobisisobutyronitrile in a mass ratio of 30-48:15-22:0.1-0.

2.

5. The PPDO composite material according to claim 1, characterized in that, The specific preparation method of the polydopamine-coated Janus microparticles is as follows: Add silica-based Janus particles to deionized water, disperse ultrasonically, adjust the pH to 8.5 with sodium hydroxide, then add dopamine hydrochloride powder and anhydrous ethanol, stir at 500-600 rpm for 24-26 h, centrifuge and filter the product, wash the precipitate, and vacuum dry to constant weight to obtain polydopamine-coated Janus microparticles.

6. The PPDO composite material according to claim 5, characterized in that, The ratio of the silica-based Janus particles, deionized water, dopamine hydrochloride powder, and anhydrous ethanol is 3-5g: 500-600mL: 0.4-0.6g: 250-300mL.

7. The PPDO composite material according to claim 1, characterized in that, The specific preparation method of the antibacterial composite particles is as follows: Janus microparticles coated with polydopamine, zinc salt, and deionized water were added to a reaction vessel and stirred until zinc nitrate hexahydrate was completely dissolved. The mixture was then ultrasonically dispersed for 10-20 minutes. 2-methylimidazole and epigallocatechin gallate were dissolved in methanol and added to the reaction vessel. The mixture was stirred for 1-2 minutes, centrifuged at 8000-9000 rpm for 20-30 minutes, filtered, and the filter cake was washed with methanol 3-5 times and freeze-dried for 48-50 hours to obtain antibacterial composite particles.

8. The PPDO composite material according to claim 7, characterized in that, The ratio of polydopamine-coated Janus microparticles, zinc salt, deionized water, 2-methylimidazole, epigallocatechin gallate, and methanol is 0.8-1.2g: 4.2-5.2g: 140-200mL: 9.24-12.14g: 140-200mg: 280-350mL; The zinc salt is any one of zinc acetate, zinc chloride, and zinc nitrate hexahydrate.

9. The PPDO composite material according to claim 1, characterized in that, The PPDO composite material is prepared through the following steps: Poly(p-dioxanone), polylactic acid, antibacterial composite particles, quinone zirconia, and tributyl acetyl citrate were added to a reaction vessel and stirred for 10-20 minutes. The mixture was then evacuated at room temperature for 10-20 minutes. Under a nitrogen atmosphere, the system was heated to 140-150°C and melt-blended at a constant temperature for 10-20 minutes to obtain the PPDO composite material.

10. A method for preparing a barbed absorbable suture, characterized in that, Includes the following steps: PPDO composite material was melt-spun at 145℃ and 1.1MPa nitrogen pressure. The nascent fibers were quenched in an ice-water bath for 5 minutes and then stretched 6 times at room temperature. After heat setting at 70℃ for 6 hours, an antibacterial absorbable suture was obtained and installed on a winding machine. The forward button was pressed to start moving forward. The cutter cutting angle was set to 160°, the relative cutting depth to 20%, and the barb spacing to 1mm. Mechanical cutting was performed in a spiral arrangement. During the cutting process, an outward turning process was applied simultaneously. When the cutter returned, it moved upward by 0.01mm to turn the bottom of the barb outward at an outward turning angle of 170°, resulting in a barbed absorbable suture. The PPDO composite material is the PPDO composite material described in any one of claims 1-9.