Composite coating suture line and preparation method thereof

Abstract

The invention provides a composite coating suture line and a preparation method thereof, and the preparation method comprises the following steps: immersing a suture line matrix into a Tris-HCl buffer solution containing dopamine hydrochloride, and carrying out a light-shielding reaction under an oscillation condition to form a polydopamine adhesion layer; adding a silver nanoparticle dispersion liquid with the surface modified by polyvinylpyrrolidone into the buffer solution reaction system, enabling the final mass concentration of the silver nanoparticles in the reaction system to be 1.0-2.0 wt%, continuing the oscillatory reaction for 8-12 hours, enabling the silver nanoparticles to be embedded into the polydopamine matrix under the chelation effect, and obtaining the polydopamine / silver nanoparticle composite material. The suture line with the polydopamine-silver nanoparticle composite coating is obtained and immersed in polytetrafluoroethylene dispersion liquid, and ultrasonic treatment is carried out for 3-10 minutes; taking out, vertically hanging and drying; and then carrying out heat preservation and heat treatment for 0.5-2 hours to form the polydopamine-silver nanoparticle / polytetrafluoroethylene composite coating suture line. According to the invention, lasting lubrication, efficient antibiosis, high interface bonding strength and excellent wear resistance can be realized at the same time, so that tissue dragging is remarkably reduced, and postoperative infection is effectively inhibited.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of sutures, and particularly relates to a composite coated suture and a preparation method thereof. BACKGROUND

[0002] The existing sutures can be divided into three categories of twisted type, braided type and monofilament type according to structural form. The twisted type and braided type sutures have obvious grooves and burrs on the surface, which generate a large friction force when passing through the tissue, easily causing tissue drag deformation. At the same time, these groove structures are easy to retain blood, tissue fluid and bacteria due to capillary effect, thereby increasing the risk of postoperative infection. To solve this problem, monofilament sutures are widely used due to their relatively smooth surface, which can reduce friction and bacterial retention to some extent. However, monofilament sutures cannot be processed to be too thick, otherwise bending difficulty and knotting instability will occur in clinical use, limiting their application range.

[0003] In recent years, barbed monofilament sutures have been developed and used in clinical practice. This type of suture realizes knotless fixation by processing barb structures on the surface of the monofilament, thereby simplifying the surgical operation and reducing the complications related to knotting. However, the barb processing process weakens the overall tensile strength of the suture; at the same time, the barb edges still increase the tissue resistance, and bacteria cannot be avoided from gathering at the root of the barb, so the clinical application range is still limited.

[0004] In terms of antibacterial modification, the existing technology mainly adopts the following three strategies:

[0005] (1) Physical mixing of nano-silver particles. For example, Chinese patent CN106835688A discloses an antibacterial suture directly mixed with nano-silver particles in the suture and a preparation method thereof. Although this method can endow the suture with broad-spectrum antibacterial activity, the exposed nano-silver particles significantly increase the surface roughness of the suture, leading to an increase in the friction coefficient, which in turn aggravates tissue damage; and the silver particles are easy to fall off, posing a potential cytotoxicity risk.

[0006] (2) Surface coating of chitosan. For example, Chinese patent CN111514366A proposes coating a chitosan antibacterial layer on the surface of the suture. The antibacterial activity of chitosan is closely related to its concentration: at low concentrations, the antibacterial effect is insufficient, and even the degradation products of chitosan provide nutrients for bacteria, promoting bacterial reproduction; at high concentrations, the mechanical properties of the suture are significantly reduced, which is not clinically feasible.

[0007] (3) Loading of small-molecule antibacterial drugs. For example, Chinese patent CN117062634A discloses a technical solution of loading antibacterial drugs into the suture by dipping or coating. However, the burst release of antibacterial drugs and long-term use can easily lead to the emergence of drug-resistant strains, and drug residues may cause local tissue toxicity, making safety difficult to guarantee.

[0008] In view of this, the present application provides a composite coating suture and a preparation method thereof, which can simultaneously achieve long-lasting lubrication, high-efficiency antibiosis, high interfacial bonding strength and excellent wear resistance, thereby significantly reducing tissue drag and effectively inhibiting postoperative infection. SUMMARY

[0009] In view of the above problems of the prior art suture, such as high surface friction coefficient leading to tissue drag injury, groove structure easily retaining bacteria to cause infection, and existing antibacterial coating having mechanical performance decline / drug resistance / toxicity, etc., the present application provides a composite coating suture and a preparation method thereof to solve the above technical defects.

[0010] The technical scheme adopted by the present application to solve the technical problems is as follows:

[0011] In a first aspect, the present application provides a preparation method of a composite coating suture, which comprises the following steps:

[0012] S1, immerse the suture substrate into a Tris-HCl buffer solution containing dopamine hydrochloride, and react under oscillation conditions in the dark for 1-3 hours to form a polydopamine adhesion layer; add a silver nanoparticle dispersion solution with a surface modified by polyvinylpyrrolidone to the buffer reaction system, so that the final mass concentration of the silver nanoparticles in the reaction system is 1.0-2.0 wt%, and continue to oscillate for 8-12 hours to enable the silver nanoparticles to be embedded in the polydopamine matrix through chelation, thereby obtaining a suture with a polydopamine-silver nanoparticle composite coating;

[0013] S2, immerse the suture with the polydopamine-silver nanoparticle composite coating obtained in step S1 into a polytetrafluoroethylene dispersion solution, and treat with ultrasonic waves for 3-10 minutes; after taking out, vertically hang and dry in an environment with a temperature of 25-30℃ and a relative humidity of <50% for 24-48 hours; then heat to 300-340℃ at a rate of 4-6℃ / min, and heat treat for 0.5-2 hours to form a suture with a polydopamine-silver nanoparticle / polytetrafluoroethylene composite coating.

[0014] Preferably, before step S1, the suture substrate is further subjected to a pretreatment step: ultrasonic cleaning of the suture substrate in anhydrous ethanol at a frequency of 40-60 kHz for 5-15 minutes, and then vacuum drying at 40-60℃ for 1-2 hours.

[0015] Preferably, in step S1, the concentration of the Tris-HCl buffer solution is 8-12 mM, and the pH value is 8.2-8.8, and the pH value is adjusted by using a 0.1-1 M NaOH solution.

[0016] Preferably, in step S1, the concentration of dopamine hydrochloride in the buffer is 1.5-2.5 mg / mL, and the dissolution is performed at 20-30℃ with magnetic stirring for 10-30 minutes until complete dissolution.

[0017] Preferably, in step S1, the oscillation reaction is performed in a constant temperature oscillator at a temperature of 35-39℃ and a rotation speed of 120-180 rpm, and the light-proof condition is achieved by wrapping the reaction container with aluminum foil.

[0018] Preferably, in step S1, after the reaction is completed, the suture with polydopamine-silver nanoparticle composite coating is washed, including the following three stages: first, rinsing with deionized water for 30-60 seconds, then washing with ultrapure water under 40 kHz ultrasonic conditions for 1-2 minutes, and finally rinsing with anhydrous ethanol for 10-20 seconds.

[0019] Preferably, in step S2, the polytetrafluoroethylene dispersion is pretreated before use: first, water bath ultrasonic dispersion at 25-35℃ for 5-15 minutes, and then filtered through a 200-400 mesh screen to remove agglomerates.

[0020] Preferably, in step S2, the heat treatment is performed in a muffle furnace, and the oxygen concentration in the furnace is controlled at 18-22%, and after the heat treatment is completed, the furnace is cooled to below 50℃ and taken out.

[0021] Preferably, after step S2, a post-treatment step is included: the obtained composite coating suture is irradiated under a UV lamp for 15-30 minutes for surface sterilization, and then vacuum packaged.

[0022] In a second aspect, the present application provides a composite coating suture, which is prepared by any of the above-mentioned preparation methods, and has a polydopamine-silver nanoparticle / polytetrafluoroethylene composite coating on the surface, and the composite coating includes a polydopamine-silver nanoparticle intermediate layer combined with the suture substrate and a polytetrafluoroethylene outer layer covering the intermediate layer.

[0023] In summary, compared with the prior art, the composite coating suture and its preparation method provided by the present application have the following beneficial effects:

[0024] (1) The lubrication performance is significantly improved: the outer layer of polytetrafluoroethylene gives the suture a persistent low-friction surface, greatly reducing the resistance during tissue passage and effectively reducing tissue drag and damage.

[0025] (2) The antibacterial activity is persistent and efficient: the polydopamine-silver nanoparticle intermediate layer can continuously release antibacterial factors during clinical use, maintaining broad-spectrum and efficient inhibition of common pathogenic bacteria, and significantly reducing the risk of postoperative infection.

[0026] (3) Interface bonding strength is significantly improved: polydopamine is used as "molecular glue" to firmly anchor polytetrafluoroethylene with the substrate, and the coating is tightly combined with the substrate, and there is no hidden danger of falling off during suturing and knotting.

[0027] (4) Wear resistance is greatly enhanced: the composite structure effectively inhibits the expansion of polytetrafluoroethylene microcracks, so that the coating remains intact after repeated friction, prolonging the effective service life of the suture.

[0028] (5) Excellent biological safety: the materials used are medical grade, and silver nanoparticles are stably embedded by polydopamine, without free particle release; no small molecule drugs, avoiding cytotoxicity and drug resistance problems

[0029] (6) Strong process compatibility: mild preparation conditions, suitable for a variety of absorbable and non-absorbable suture substrates, simple process steps, easy to scale up production and clinical promotion. BRIEF DESCRIPTION OF DRAWINGS

[0030] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments made with reference to the accompanying drawings:

[0031] Figure 1 is a preparation method flow chart of the composite coated suture according to the present application;

[0032] Figure 2 is a scanning electron microscope image of PDA and PTFE film on the suture substrate according to the present application. DETAILED DESCRIPTION

[0033] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific examples described herein are merely intended to explain the related application, and not to limit the application. In addition, it should be noted that only parts related to the application are shown in the drawings for ease of description.

[0034] It should be noted that the embodiments and features in the embodiments in the present application can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and examples.

[0035] Figure 1 shows the preparation method flow chart of the composite coated suture of the present application, as shown in Figure 1 The preparation method of the composite coated suture of the present application includes the following steps:

[0036] S1, immerse the suture base into Tris-HCl buffer solution containing dopamine hydrochloride, and react for 1-3 hours under oscillation condition in dark, to form polydopamine adhesion layer; add polyvinylpyrrolidone modified silver nanoparticles dispersion (preferably, the particle size of silver nanoparticles is 15-30 nm) into the reaction system of buffer solution, so that the final mass concentration of silver nanoparticles in the reaction system is 1.0-2.0 wt%, and continue to oscillate for 8-12 hours, so that the silver nanoparticles are embedded into the base through catechol group chelation of polydopamine, to obtain suture with polydopamine-silver nanoparticle composite coating.

[0037] Before step S1, the pre-treatment step of suture base is further included: place the suture base in anhydrous ethanol, ultrasonic clean for 5-15 minutes under the frequency of 40-60 kHz, and then vacuum dry at 40-60℃ for 1-2 hours.

[0038] In step S1, the suture base is one of polyglycolic acid, polylactic acid, poly-p-dioxanone, polypropylene or silk thread. The concentration of Tris-HCl buffer solution is 8-12 mM, and the pH value is 8.2-8.8, and the pH value is adjusted by 0.1-1 M NaOH solution. The concentration of dopamine hydrochloride in the buffer solution is 1.5-2.5 mg / mL, and the magnetic stirring is performed at 20-30℃ for 10-30 minutes until complete dissolution. The oscillation reaction is carried out in a constant temperature oscillator, the temperature is 35-39℃, the rotation speed is 120-180 rpm, and the light-proof condition is realized by wrapping the reaction container with aluminum foil. After the reaction is completed, the suture with polydopamine-silver nanoparticle composite coating is cleaned, including the following three stages: first, rinse with deionized water for 30-60 seconds, then clean with ultrapure water under 40 kHz ultrasonic condition for 1-2 minutes, and finally rinse with anhydrous ethanol for 10-20 seconds to quickly dehydrate and promote drying.

[0039] S2, immerse the suture with polydopamine-silver nanoparticle composite coating obtained in step S1 into polytetrafluoroethylene dispersion, and ultrasonic treat for 3-10 minutes; after taking out, vertically hang dry in the environment of 25-30℃ and relative humidity <50% for 24-48 hours; then heat to 300-340℃ at the rate of 4-6℃ / min, and heat treat for 0.5-2 hours, to form polydopamine-silver nanoparticle / polytetrafluoroethylene composite coating suture.

[0040] In step S2, the polytetrafluoroethylene dispersion liquid is pretreated before use: first ultrasonic dispersion in water bath at 25-35℃ for 5-15 minutes, then filtered through a 200-400 mesh screen to remove agglomerates. The heat treatment is carried out in a muffle furnace, and the oxygen concentration in the furnace is controlled at 18-22%. After the heat treatment is completed, the sample is taken out after the furnace is cooled to below 50℃. After step S2, a post-treatment step is included: the obtained composite coating suture is irradiated under a UV lamp for 15-30 minutes for surface sterilization, and then vacuum packaged.

[0041] The application also provides a composite coating suture prepared by any of the above preparation methods, wherein the surface of the composite coating suture has a polydopamine-silver nanoparticle / polytetrafluoroethylene composite coating, and the composite coating comprises a polydopamine-silver nanoparticle intermediate layer combined with the suture substrate and a polytetrafluoroethylene outer layer covering the intermediate layer.

[0042] The thickness of the polydopamine-silver nanoparticle intermediate layer is 80-150 nm, and the silver nanoparticles are uniformly distributed in the polydopamine matrix with a distribution density of 500-2000 / μm 2 The thickness of the polytetrafluoroethylene outer layer is 0.5-2 μm, the surface roughness Ra is <0.1 μm, and the bonding strength with the intermediate layer is ≥5 MPa.

[0043] Example 1

[0044] The present embodiment provides a preparation method of a composite coating suture, and the specific steps are as follows:

[0045] S1, take 5-0 PGA absorbable monofilament suture (wire diameter 0.15 mm) as the substrate, and first pretreat it: ultrasonic cleaning in anhydrous ethanol at a frequency of 40 kHz for 10 minutes, and then vacuum drying at 50℃ for 1.5 hours.

[0046] Prepare a Tris-HCl buffer solution with a concentration of 10 mM and pH = 8.5, and add dopamine hydrochloride to make the concentration 2 mg / mL. Stir magnetically at 25℃ for 20 minutes until completely dissolved. Immerse the pretreated suture in the solution and place it in a constant temperature oscillator at 37℃ and 150 rpm in the dark for 2 hours. Then add PVP modified silver nanoparticle dispersion liquid (concentration 3.2 mg / mL, particle size 20±5 nm) drop by drop to make the mass concentration of AgNPs in the system 1.0%, and continue to react under the same conditions for 10 hours. After the reaction is completed, rinse with deionized water for 45 seconds, ultrapure water ultrasonic cleaning (40 kHz) for 1.5 minutes, anhydrous ethanol rinsing for 15 seconds, and finally air dry in a clean air at 25℃ for 12 hours to obtain a PDA-AgNPs coating suture.

[0047] S2, the suture is immersed in a 10 wt% PTFE dispersion (preferably DuPont TM DISP 30, pretreated by 10 minutes of ultrasonic treatment in a 30 °C water bath and sieved through a 300 mesh screen), is ultrasonically treated for 5 minutes at a power of 100 W and a frequency of 40 kHz. After removal, the suture is hung vertically to dry in an environment of 25 °C and 45% relative humidity for 24 hours, then transferred to a muffle furnace and heated to 300 °C at a rate of 5 °C / min, and held at 300 °C for 1 hour. The furnace is then allowed to cool to room temperature. Finally, the resulting composite coated suture is sterilized by irradiation under a UV lamp for 20 minutes, and vacuum packaged.

[0048] The product of this example is tested for performance:

[0049] 1. Abrasion resistance test: A YG(B)401E fiber friction and wear tester is used to wind the composite coated suture around a 5 mm diameter stainless steel rubbing column at a certain tension, and a 2 N radial load is applied to the rubbing column. The composite coated suture is reciprocally rubbed at a frequency of 200 times / min, and the number of cycles at which the composite coated suture is broken is recorded. The result shows that the number of cycles at which the composite coated suture is broken is 3520.

[0050] 2. Lubricity test: A UMT-TriboLab friction and wear tester is used to fix the composite coated suture sample, and a standard medical silicone rubber sheet (Shore A hardness 50) is used to press the sample at a force of 2.5 N. The composite coated suture is vertically pulled at a speed of 500 mm / min, and the dynamic friction force is recorded and the average friction coefficient is calculated. The result shows that the friction coefficient is 0.13.

[0051] 3. Coating interfacial shear strength test: A microsphere debonding method is used to vertically embed a single composite coated suture in an epoxy resin microsphere (about 3 mm in diameter) and cure. A diamond probe is used to push the end of the fiber at a rate of 0.5 mm / min, and the maximum debonding force F is recorded. The interfacial shear strength (IFSS) is calculated by the formula τ = F / (π x d x L) (where d is the diameter of the composite coated suture and L is the length of the composite coated suture embedded in the resin). The result shows that the interfacial shear strength is 5.8 MPa.

[0052] 4. Antibacterial performance test: According to GB / T 20944.3-2008 "Evaluation of antibacterial properties of textiles Part 3: Shake flask method", Staphylococcus aureus (ATCC 6538) and Escherichia coli (ATCC 25922) are used as test bacteria. 0.75 g of the composite coated suture sample is added to a flask containing 5 mL of bacterial suspension (concentration of 1.0 x 10^5-10^6 CFU / mL), and after 4 hours of contact at 37 °C with shaking at 150 rpm, the bacterial liquid is taken for viable bacterial count. The result shows that the antibacterial rate against Staphylococcus aureus and Escherichia coli is >99.5%.

[0053] Example 2

[0054] The difference between this example and Example 1 is that the mass concentration of AgNPs in the system is 2.0%, the PTFE dispersion liquid concentration is 2wt%, and the heat treatment temperature is 340°C. Specifically, the silver nanoparticle dispersion liquid is added in step S1 to make the mass concentration 2.0%; in step S2, 2wt% PTFE dispersion liquid is used, and the temperature is raised to 340°C at 5°C / min during heat treatment and kept for 1 hour. The rest of the steps and parameters are the same as in Example 1.

[0055] The performance test of the product of this example was carried out, and the performance test method was the same as in Example 1. The results showed that the abrasion resistance test showed that the abrasion cycle number was 8980 times; the friction coefficient was 0.10; the interfacial shear strength of the coating was 6.5 MPa; and the antibacterial rates of Staphylococcus aureus and Escherichia coli were both >99.8%.

[0056] Example 3

[0057] The difference between this example and Example 1 is that the mass concentration of AgNPs in the system is 1.5%, the PTFE dispersion liquid concentration is 5wt%, and the heat treatment temperature is 320°C. Specifically, the silver nanoparticle dispersion liquid is added in step S1 to make the mass concentration 1.5%; in step S2, 5wt% PTFE dispersion liquid is used, and the temperature is raised to 320°C at 5°C / min during heat treatment and kept for 1 hour. The rest of the steps and parameters are the same as in Example 1.

[0058] The performance test of the product of this example was carried out, and the performance test method was the same as in Example 1. The results showed that the abrasion resistance test showed that the abrasion cycle number was 6250 times; the friction coefficient was 0.09; the interfacial shear strength of the coating was 6.2 MPa; and the antibacterial rates of the two test bacteria were both >99.6%.

[0059] Comparative Example 1

[0060] This comparative example provides a suture coated only with a PDA coating: except that no AgNPs nanoparticles and subsequent PTFE coating steps are added, the rest of the steps are the same as in Example 1. That is, only the PDA (dopamine solution) deposition in step S1 is carried out for 2 hours, and the product is obtained after washing and drying after the reaction is completed.

[0061] The performance test of the product of this comparative example was carried out, and the performance test method was the same as in Example 1. The results showed that the abrasion resistance test showed that the abrasion cycle number was 3010 times; the friction coefficient was 0.35; the interfacial shear strength of the coating was 2.8 MPa; and the antibacterial rates of Staphylococcus aureus and Escherichia coli were 85.5% and 82.3%, respectively.

[0062] Comparative Example 2

[0063] This comparative example provides a suture coated with PTFE coating only: omitting step S1, directly performing step S2 PTFE (polytetrafluoroethylene) coating on the pretreated suture substrate (concentration 10wt%, heat treatment 320℃), and the rest of the parameters are the same as example 1.

[0064] The performance test of the product of this comparative example was performed, and the performance test method was the same as example 1. The results showed that the number of grinding and breaking cycles was 3500 times; the friction coefficient was 0.12; the interfacial shear strength of the coating was 2.1 MPa; and the antibacterial rates of the two test bacteria were both <10%.

[0065] Comparative example 3

[0066] This comparative example provides a suture coated with PDA-AgNPs composite coating (without PTFE outer layer): the preparation steps are exactly the same as step S1 in example 1, i.e. no step S2 PTFE coating is performed.

[0067] The performance test of the product of this comparative example was performed, and the performance test method was the same as example 1. The results showed that the number of grinding and breaking cycles was 3500 times; the friction coefficient was 0.12; the interfacial shear strength of the coating was 2.1 MPa; and the antibacterial rates of the two test bacteria were both <10%.

[0068] The following table is a summary of the performance test results of each example and comparative example (all results are the average of three independent tests):

[0069]

[0070] The test results of the above examples and comparative examples show that the composite coating suture preparation method provided by the present application can obtain products with excellent lubricity, antibacterial property, high bonding strength and wear resistance by adjusting the process conditions within a wide parameter range. Example 2 (AgNPs 2.0%, PTFE 2wt%, 340℃) shows the best overall performance, with wear resistance more than 2.5 times that of the comparative example, friction coefficient reduced to 0.10, interfacial bonding strength reached 6.5 MPa, and antibacterial rate more than 99.8%. The two end values (example 1 and 2) and the middle value (example 3) all show significantly better overall performance than the comparative example, fully demonstrating the effectiveness and reliability of the method described in the present application, providing comprehensive performance improvement for sutures, and having significant clinical application value.

[0071] Figure 2 Scanning electron microscope (SEM) images of the composite coating of the present application at different preparation stages and different components are provided, which directly show the surface morphology, particle distribution and interfacial bonding of the coating, as follows:

[0072] Figure 2(A) shows the morphology of the surface of the pure polydopamine (PDA) coating. It can be seen that PDA is uniformly deposited in the form of dots on the suture surface, forming a continuous thin film, which provides a good foundation for the embedding of silver nanoparticles and the covering of PTFE in the subsequent process.

[0073] Figure 2 (B) is the surface of the PDA composite coating containing 2.0wt% silver nanoparticles (AgNPs). Figure 2 Compared with (A), the AgNPs (bright white particles) are uniformly embedded in the PDA matrix without obvious agglomeration, indicating that PDA effectively disperses and stabilizes AgNPs, and the two form a dense and antibacterial composite intermediate layer.

[0074] Figure 2 (C) and Figure 2 (D) respectively shows the cross-sectional structure of the interface between PDA and PTFE coating. Figure 2 (C) is the interface between pure PDA and PTFE, and it can be seen that there is a clear but tightly bonded interface between the two layers; Figure 2 (D) is the interface between PDA containing 2.0wt% AgNPs and PTFE, and the presence of AgNPs further enhances the mechanical interlocking and bonding force between the PDA layer and PTFE. There is no cracking or peeling at the interface, indicating that the composite structure has good compatibility and stability.

[0075] Figure 2 (E) and Figure 2 (F) respectively shows the surface morphology after PTFE completely covers. Figure 2 (E) is the surface of PTFE-covered pure PDA, and PTFE is in the form of a typical porous film, which is continuous and complete; Figure 2 (F) is the surface of PTFE-covered PDA+2.0wt% AgNPs composite coating, and the PTFE layer is more dense and smooth, without cracks or AgNPs seepage, indicating that PTFE successfully encapsulates the intermediate layer, forming a lubricated surface with low friction coefficient.

[0076] These electron microscope results also fully confirm that the present application realizes the uniformity, density and good interface bonding of the coating through the composite structure design of PDA-AgNPs intermediate layer and PTFE outer layer, and endows the suture with excellent lubricity, antibacterial property and durability.

[0077] Pure PTFE as a kind of self-lubricating polymer, although the friction coefficient is low, but PTFE creep is large, the shear strength between the lamellar crystals in PTFE microstructure is low when wear occurs, the crack propagation on the internal interface will cause delamination wear mechanism, so its wear performance is poor; In addition, due to the stable chemical properties of PTFE, the adhesion strength between the thin film and the substrate surface is weak. The lack of wear resistance and adhesion strength limits the application of thin PTFE film in many fields.

[0078] The addition of nano-silver improves the wear resistance of polytetrafluoroethylene coating, the addition of polydopamine improves the adhesion strength of polytetrafluoroethylene and suture substrate, and both have antibacterial properties, so that the suture has antibacterial effect, and polytetrafluoroethylene is a low-friction solid lubricant, which can reduce the drag force when the suture passes through the tissue, so the composite coating makes the suture have the dual characteristics of lubrication and antibacterial. The synergistic effect of the three not only improves the performance of the composite coating, but also makes it have antibacterial properties.

[0079] The above description is only the preferred embodiment of the present application and the explanation of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above inventive concept. For example, the above features are replaced with the technical features disclosed in the present application (but not limited to) having similar functions to form a technical solution.

Claims

1. A method of making a composite-coated suture, characterized by, The preparation method comprises the following steps: S1, immerse the suture base into a Tris-HCl buffer solution containing dopamine hydrochloride, and react under oscillation condition in dark for 1-3 hours to form a polydopamine adhesion layer; add silver nanoparticles dispersion solution with polyvinylpyrrolidone modified surface into the buffer solution reaction system, so that the final mass concentration of silver nanoparticles in the reaction system is 1.0-2.0 wt%, and continue to oscillate for 8-12 hours to make the silver nanoparticles embedded into the polydopamine matrix through chelation, thereby obtaining a suture with polydopamine-silver nanoparticle composite coating; S2, immerse the suture with polydopamine-silver nanoparticle composite coating obtained in step S1 into a polytetrafluoroethylene dispersion solution, and treat with ultrasonic for 3-10 minutes; after taking out, vertically hang and dry for 24-48 hours in an environment with temperature of 25-30℃ and relative humidity of <50%; then heat to 300-340℃ at a temperature increasing rate of 4-6℃ / min, and heat treat for 0.5-2 hours to form a polydopamine-silver nanoparticle / polytetrafluoroethylene composite coating suture.

2. The method of claim 1, wherein the composite coating suture is prepared by the steps of: Before step S1, the suture base is pretreated by placing it into anhydrous ethanol, ultrasonic cleaning at a frequency of 40-60 kHz for 5-15 minutes, and then vacuum drying at 40-60℃ for 1-2 hours.

3. The method for preparing the composite coated suture according to claim 1, characterized in that, In step S1, the concentration of the Tris-HCl buffer solution is 8-12 mM, and the pH value is 8.2-8.8, and the pH value is adjusted by using 0.1-1 M NaOH solution.

4. The method of claim 1, wherein the composite coating suture is prepared by the steps of: In step S1, the concentration of dopamine hydrochloride in the buffer solution is 1.5-2.5 mg / mL, and the solution is completely dissolved by magnetic stirring at 20-30℃ for 10-30 minutes.

5. The method of claim 1, wherein the composite coating suture is prepared by the steps of: In step S1, the oscillation reaction is carried out in a constant temperature oscillator, the temperature is 35-39℃, the rotation speed is 120-180 rpm, and the light-proof condition is realized by wrapping the reaction container with aluminum foil.

6. The method of claim 1, wherein the composite coating suture is prepared by the steps of: In step S1, after the reaction, the suture with polydopamine-silver nanoparticle composite coating is cleaned, which comprises the following three stages: first, rinse with deionized water for 30-60 seconds, then clean with ultrapure water under 40 kHz ultrasonic condition for 1-2 minutes, and finally rinse with anhydrous ethanol for 10-20 seconds.

7. The method of claim 1, wherein the composite coating suture is prepared by the steps of: In step S2, the polytetrafluoroethylene dispersion solution is pretreated before use: first, ultrasonic dispersion in water bath at 25-35℃ for 5-15 minutes, and then filter through a 200-400 mesh screen to remove agglomerates.

8. The method of claim 1, wherein the composite-coated suture is prepared by the steps of: In step S2, the heat treatment is carried out in a muffle furnace, and the oxygen concentration in the furnace is controlled at 18-22%, and after the heat treatment, the furnace is cooled to below 50℃ before taking out.

9. The method of claim 1, wherein the composite coating suture is prepared by the steps of: After step S2, a post-treatment step is further included: irradiate the obtained composite coating suture under ultraviolet lamp for 15-30 minutes for surface sterilization, and then vacuum package.

10. A composite-coated suture, characterized by, The composite coating suture prepared by the preparation method of any one of claims 1-9 has a polydopamine-silver nanoparticle / polytetrafluoroethylene composite coating on the surface, and the composite coating comprises a polydopamine-silver nanoparticle intermediate layer combined with the suture base and a polytetrafluoroethylene outer layer covering the intermediate layer.

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