A wound suture film with absorbable healing promotion function and a preparation method thereof

Abstract

This invention discloses an absorbable wound suture membrane with healing-promoting function and its preparation method. The method involves preparing an amorphous PGA membrane by pressure heat treatment to eliminate crystallization in PGA particles; obtaining SF freeze-dried powder from silkworm cocoons after degumming, dissolving, washing, purifying, and drying; mixing the amorphous PGA membrane and SF freeze-dried powder in HFIP to prepare a PGA / SF composite electrospinning solution; spinning the PGA / SF composite electrospinning solution after initially setting spinning parameters to obtain a PGA / SF composite electrospinned membrane; and finally loading active factors onto the PGA / SF composite electrospinned membrane to obtain an absorbable wound suture membrane with healing-promoting function. This invention achieves precise matching between the material degradation cycle and the epidermal-dermal regeneration stage by specifically binding growth factors to the β-sheet domain of silk fibroin, synergistically enhancing the mechanical properties of PGA, and also improves axial tensile strength.

Description

Technical Field

[0001] This invention belongs to the field of wound suture membrane technology, specifically relating to an absorbable wound suture membrane with healing-promoting function and its preparation method. Background Technology

[0002] Wound suturing is a core aspect of surgical procedures and trauma repair, directly impacting tissue healing quality and functional recovery. Ideal suture materials must meet multiple requirements: First, they must possess sufficient mechanical strength to maintain wound closure and prevent secondary tearing; second, they must dynamically adapt to the tissue healing process, providing early support while gradually degrading and being absorbed later to avoid chronic inflammation or scar hyperplasia caused by foreign body residue; more importantly, modern medicine demands a higher level of proactive intervention in healing from suture materials, directly regulating cell behavior and promoting angiogenesis and tissue regeneration through the material's own functions or loaded with active ingredients. However, traditional suture materials primarily focus on mechanical properties and degradability, offering limited functionality and failing to meet the repair needs of complex wounds (such as diabetic ulcers and burn wounds). Statistics show that approximately 15% of chronic wounds worldwide experience delayed healing or infection due to insufficient suture material functionality. Therefore, there is an urgent need to develop novel suture materials that combine mechanical adaptability, controllable degradation, and proactive healing promotion.

[0003] Currently, commonly used absorbable suture materials in clinical practice mainly include polylactic acid (PLA), polyglycolic acid (PGA), and their copolymers (such as poly(lactic-co-glycolic acid), PLGA). PLA has a relatively long degradation period (12–24 months), easily triggering a local acidic microenvironment and leading to aseptic inflammation. PGA degrades faster (4–6 weeks), but its mechanical strength decays prematurely, making it difficult to match the healing cycle of deep tissues. Furthermore, these synthetic polymers lack cell affinity and cannot provide a biomimetic microenvironment for the wound, resulting in low cell adhesion and slow proliferation. Natural materials such as collagen sutures have good biocompatibility, but their mechanical properties are poor, their degradation rate is uncontrollable, and they pose an immunogenic risk. In recent years, electrospinning technology has been used to prepare nanofiber suture membranes, mimicking the extracellular matrix (ECM) by controlling fiber morphology; however, single-material systems still struggle to achieve synergistic optimization of mechanical properties, degradation rate, and bioactivity.

[0004] To overcome the limitations of traditional materials, researchers have developed various novel suture membranes through composite modification and functionalized loading strategies. However, significant technical bottlenecks remain. For example, Chinese invention patent application CN117339012A discloses "A silk fibroin-antimicrobial peptide-guided bone tissue regeneration antimicrobial barrier membrane and its preparation method and application." This application achieves antimicrobial effects by encapsulating antimicrobial peptides within the silk fibroin molecular structure for sustained drug release. However, the sustained release time of the antimicrobial peptides is only 4 days, which may be insufficient to meet the long-term needs of bone regeneration. Annealing treatment may also affect the mechanical properties or biocompatibility of the material. Another example is Chinese invention patent application CN111744050A, which discloses "Preparation of graphene oxide-daptomycin / epidermal growth factor composite dressing and its effect on wound healing." This application not only achieves good antimicrobial effects and growth-promoting properties but also has significant benefits for wound healing. However, the binding stability of the graphene oxide membrane with dopamine and its long-term biocompatibility may affect the actual application effect of the material in the wound environment. For example, Chinese invention patent application CN108066818A discloses "a biomimetic bilayer sustained-release growth factor membrane". This application includes two layers, a positively charged layer and a negatively charged layer, which can achieve simultaneous sustained release of negatively charged and positively charged growth factors. However, this biomimetic bilayer membrane may lack an adaptive regulatory mechanism for complex physiological environments (such as dynamic pH changes or enzymatic hydrolysis), and there is a risk that the sustained-release period will become disconnected from the repair process in practical applications. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a wound suture membrane with absorbable healing-promoting function and its preparation method. By specifically binding growth factors through the β-sheet domain of silk fibroin and synergistically enhancing the mechanical properties of polyglycolic acid, the material degradation cycle is precisely matched with the epidermal-dermal regeneration stage. Furthermore, the axial tensile strength is improved to a certain extent, which helps to overcome the technical bottlenecks of asynchronous degradation and healing of traditional materials and sudden release and inactivation of growth factors.

[0006] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0007] A method for preparing an absorbable wound suture membrane with healing-promoting properties includes the following steps:

[0008] Step 1) Select polyglycolic acid particles with a set molecular weight and viscosity as one of the raw materials, and subject them to pressure heat treatment to eliminate the crystalline structure, thereby preparing an amorphous polyglycolic acid film with significantly improved solubility and processing performance.

[0009] Step 2) Select an appropriate amount of silkworm cocoons as one of the raw materials, and then perform degumming, dissolving, washing, purification and drying treatments on them in sequence to obtain silk fibroin freeze-dried powder;

[0010] Step 3) Select hexafluoroisopropanol as solvent, and mix the prepared amorphous polyglycolic acid film and the prepared silk fibroin lyophilized powder in hexafluoroisopropanol according to a certain mass ratio to prepare a polyglycolic acid / silk fibroin composite electrospinning solution.

[0011] Step 4) The prepared polyglycolic acid / silk fibroin composite electrospinning solution is loaded into a syringe and connected to an electrospinning device. After initially setting the spinning parameters, electrospinning begins. During the spinning process, the spinning parameters are adjusted to obtain a nanofiber membrane with a diameter of 200-800 nm, namely a polyglycolic acid / silk fibroin composite electrospinned membrane.

[0012] Step 5) Using a low-temperature oscillation method, a coaxial electrospinning method, or a ternary electrospinning method, the active factor is loaded onto the prepared polyglycolic acid / silk fibroin composite electrospinned membrane to obtain a polyglycolic acid / silk fibroin / active factor ternary composite electrospinned membrane, which is a wound suture membrane with absorbable healing-promoting function.

[0013] Furthermore, in step 1, the molecular weight of the polyglycolic acid particles is 12-18 kDa, and the viscosity of the polyglycolic acid particles is 1.2-1.7 dL / g.

[0014] Furthermore, in step 1, the pressure heat treatment employs a hot-pressing-liquid nitrogen quenching method. By utilizing the principle of heating followed by cooling, the crystal structure of the polyglycolic acid is eliminated, thereby significantly improving the material's solubility and processing performance. The specific method is as follows:

[0015] Polyglycolic acid granules are placed in a hot press and hot-pressed for 30 to 60 seconds at a temperature of 40 to 260°C and a pressure of 2 to 5 MPa. After hot pressing, the polyglycolic acid film is quickly transferred to a liquid nitrogen environment for quenching for 1 to 2 minutes to obtain an amorphous polyglycolic acid film.

[0016] The crystallinity of the amorphous polyglycolic acid film obtained after pressure heat treatment is significantly reduced, while its solubility and processability are significantly improved.

[0017] Furthermore, in step 2, the specific method for preparing the silk fibroin lyophilized powder is as follows:

[0018] Weigh out a certain amount of silkworm cocoons and cut them into pieces;

[0019] The degumming process is carried out using sodium carbonate. Specifically, the shredded silkworm cocoons are placed in a sodium carbonate solution and treated at 90-100℃ for 30-60 minutes to remove sericin and impurities from the surface of the silk.

[0020] Wash the degummed silk repeatedly with deionized water 5 to 8 times to remove residual sericin and alkali. Then place the washed degummed silk in a ventilated place and let it air dry naturally for 24 hours at a temperature of 25°C and a relative humidity of 50% to 60%.

[0021] The degummed silk was dissolved using a lithium bromide dissolution process. Specifically, the dried degummed silk fibers were immersed in a lithium bromide solution and heated at 50–80°C for 4–6 hours to fully dissolve the silk fibers and obtain a silk fibroin solution.

[0022] The silk fibroin solution was purified by dialysis. Specifically, the prepared silk fibroin solution was placed in a dialysis bag with a molecular weight cutoff of 2000-4000 Da and dialyzed for 60-80 hours. The dialysis solution was replaced every 8 hours to remove small molecule impurities from the silk fibroin solution, thereby obtaining a clear silk fibroin solution.

[0023] The clarified silk fibroin solution was diluted and phosphate buffer was added to adjust the pH and stability of the silk fibroin solution.

[0024] The purified silk fibroin solution was dispensed into vials, flash-frozen in liquid nitrogen, and then freeze-dried in a freeze dryer for 50–80 hours to finally obtain a silk fibroin freeze-dried powder with a purity of over 95%.

[0025] Furthermore, in step 3, the specific method for preparing the polyglycolic acid / silk fibroin composite electrospinning solution is as follows:

[0026] Weigh a certain amount of the prepared amorphous polyglycolic acid film and add it to hexafluoroisopropanol solvent to prepare a polyglycolic acid solution. Place the prepared polyglycolic acid solution in a constant temperature water bath at 60-80℃ and heat and stir for 6-8 hours until the amorphous polyglycolic acid film is completely dissolved to form a uniform and transparent polyglycolic acid electrospinning solution. Then add silk fibroin lyophilized powder to the polyglycolic acid electrospinning solution at a certain mass ratio and stir at room temperature for 12-14 hours to fully disperse the silk fibroin lyophilized powder in the polyglycolic acid electrospinning solution, and obtain a semi-transparent milky white polyglycolic acid / silk fibroin composite electrospinning solution.

[0027] Alternatively, accurately weigh amorphous polyglycolic acid film and SF lyophilized powder according to a certain mass ratio; add the weighed amorphous polyglycolic acid film and silk fibroin lyophilized powder together to hexafluoroisopropanol to prepare a mixed solution; place the prepared mixed solution in a constant temperature water bath at 40-50℃ and heat and stir for 8-10 hours until the amorphous polyglycolic acid film and silk fibroin lyophilized powder are completely dissolved to obtain a stable and semi-transparent milky white polyglycolic acid / silk fibroin composite electrospinning solution;

[0028] Alternatively, weigh a certain amount of the prepared amorphous polyglycolic acid film and add it to hexafluoroisopropanol to prepare a polyglycolic acid solution; place the prepared polyglycolic acid solution in a constant temperature water bath at 60-80℃ and heat and stir for 6-8 hours until the amorphous polyglycolic acid film is completely dissolved to obtain a uniform and transparent polyglycolic acid electrospinning solution; weigh a certain amount of the prepared lyophilized silk fibroin powder and dissolve it in a formic acid / water mixed solvent to prepare a silk fibroin solution; then sonicate for 30-50 minutes to degas to ensure that the silk fibroin solution is uniform and free of bubbles; mix the polyglycolic acid electrospinning solution and the silk fibroin solution according to the mass ratio, add the emulsifier Tween-80, and sonicate for 5-8 minutes under ice bath conditions to form a stable oil-in-water emulsion, thus obtaining a semi-transparent milky white polyglycolic acid / silk fibroin composite electrospinning solution.

[0029] Furthermore, in step 4, the spinning parameters include spinning voltage, collection distance, feeding speed, ambient temperature, and ambient humidity; wherein,

[0030] Before electrospinning begins, the initial settings are as follows: spinning voltage 10–25 kV, collection distance 12–20 cm, liquid feeding rate 0.5–1.5 mL / h, ambient humidity 20–30 °C, and ambient temperature 25%–40% RH.

[0031] During electrospinning, the spinning voltage was optimized to 16–20 kV, the collection distance to 14–20 cm, the liquid feeding rate to 0.5–1.5 mL / h, the ambient humidity to 20–30 °C, and the ambient temperature to 25%–40% RH.

[0032] Furthermore, in step 5, the specific implementation of the low-temperature oscillation method is as follows:

[0033] The prepared polyglycolic acid / silk fibroin composite electrospun membrane was placed in an alkaline fibroblast growth factor solution with a concentration gradient of 20-100 μg / mL and subjected to shaking immersion at 2-6℃ for 4-48 hours to allow the alkaline fibroblast growth factor to be fully adsorbed on the fiber surface and inside the polyglycolic acid / silk fibroin composite electrospun membrane, thereby obtaining a polyglycolic acid / silk fibroin / active factor ternary composite electrospun membrane.

[0034] Furthermore, in step 5, the specific implementation of the coaxial electrospinning method is as follows:

[0035] Vascular endothelial growth factor was selected as the active ingredient. The lyophilized vascular endothelial growth factor powder and bovine serum albumin protectant were dissolved together in PBS buffer to prepare the bovine serum albumin protectant-vascular endothelial growth factor complex.

[0036] Weigh a certain amount of bovine serum albumin protectant-vascular endothelial growth factor complex and polyvinyl alcohol, add an appropriate amount of PBS buffer, and stir in a low-temperature magnetic stirrer at 3-6℃ for 4-5 hours to ensure uniform dispersion, thus obtaining a core layer drug loading solution.

[0037] Based on step 4, the polyglycolic acid / silk fibroin composite electrospinning solution is loaded into a syringe and connected to the shell channel of the coaxial nozzle through a conduit. The core layer drug-loaded solution is loaded into another syringe and connected to the core layer channel of the coaxial nozzle through a conduit.

[0038] After initially setting the spinning parameters, coaxial electrospinning was started. The polyglycolic acid / silk fibroin composite electrospinning solution formed the shell layer of nanofibers, and the core layer drug loading solution formed the core layer of nanofibers. By adjusting the spinning parameters during the coaxial spinning process, a nanofiber membrane with a core-shell structure was obtained, namely the polyglycolic acid / silk fibroin / active factor ternary composite electrospinned membrane.

[0039] After spinning, the resulting polyglycolic acid / silk fibroin / active factor ternary composite electrospun membrane is immediately placed in a dry place to remove residual solvent; then, glutaraldehyde vapor is used for crosslinking for 2-4 hours, and the staged release of vascular endothelial growth factor is achieved by controlling the degree of crosslinking.

[0040] Furthermore, in step 5, the specific implementation of the ternary electrospinning method is as follows:

[0041] Basic fibroblast growth factor was dissolved in PBS buffer to prepare an active factor solution. The active factor solution was slowly added to the polyglycolic acid / silk fibroin composite electrospinning solution and gently stirred for 30-40 minutes to complete the loading of basic fibroblast growth factor and obtain a polyglycolic acid / silk fibroin / active factor ternary composite electrospinning solution.

[0042] The prepared polyglycolic acid / silk fibroin / active factor ternary composite electrospinning solution was injected into a syringe and connected to the corresponding needle of the electrospinning equipment. Then it was left to stand for a period of time until the bubbles disappeared.

[0043] After setting the initial spinning conditions, ternary electrospinning begins. During the electrospinning process, the fiber formation process is controlled by adjusting the electric field strength and spinning distance. Finally, a nanofiber membrane with uniform thickness, low orientation, and no beading is produced, namely a polyglycolic acid / silk fibroin / active factor ternary composite electrospinned membrane.

[0044] The prepared polyglycolic acid / silk fibroin / active factor ternary composite electrospun film was exposed in a 75% ethanol atmosphere for 12-14 hours to enhance the stability of silk fibroin, and then dried at 40°C for one day to remove residual solvent.

[0045] Finally, gamma irradiation sterilization was used to ensure the sterility of the material, ultimately producing a wound suture membrane with absorbable healing-promoting function.

[0046] A wound suture membrane with absorbable healing-promoting function prepared by the above preparation method.

[0047] The key design focus of this invention is to optimize electrospinning process parameters to maintain the activity and controllable release of basic fibroblast growth factor (bFGF) in PGA and SF composite fibers. This invention emphasizes the construction of a three-dimensional nanofiber network structure, utilizing the biodegradability of PGA to provide mechanical support, the natural biocompatibility of SF to enhance cell adhesion, and extending the bioactivity cycle of bFGF through a sustained-release system carried by the fiber carrier. Ultimately, this forms a multifunctional composite membrane that combines physical barrier hemostasis, gradient release of repair-promoting factors, and guidance of tissue regeneration. The process design of this invention particularly emphasizes the optimization of spinning solution ratios and the control of electric field parameters, providing a technical foundation for the development of intelligent hemostatic materials with clinical translational potential.

[0048] The beneficial effects of this invention are as follows:

[0049] This invention innovatively proposes the use of PGA and SF as core substrates, combined with gradient electrospinning technology, to prepare an absorbable suture membrane with healing-promoting functions. This invention achieves a precise match between the material degradation cycle (14-28 days) and the epidermal-dermal regeneration stage by specifically binding growth factors to the β-sheet domain of silk fibroin, synergistically enhancing the mechanical properties of PGA. Furthermore, it improves axial tensile strength, solving problems such as the mismatch between degradation rate and tissue regeneration cycle, poor growth factor loading stability, and insufficient mechanical properties of existing suture materials.

[0050] The wound suture membrane prepared by this invention is based on a PGA and SF composite system. By loading bFGF growth factor to construct a healing-promoting active interface, while promoting healing, the controllable degradation characteristics of PGA and the natural biocompatibility of SF work synergistically to ensure that the material is absorbed synchronously with tissue regeneration, avoiding the risk of secondary surgery.

[0051] The three-dimensional nanofiber network of the suture membrane of this invention accelerates platelet enrichment and coagulation cascade reaction through physical adsorption effect, and continuously stimulates vascular endothelial cell migration and proliferation through the sustained release mechanism of bFGF, thus simultaneously achieving mechanical hemostasis and active healing functions, shortening the repair cycle by more than 30% compared with traditional materials.

[0052] This invention employs gradient electrospinning technology to precisely control fiber diameter, pore structure, and spatial distribution of growth factors, constructing a biomimetic extracellular matrix microenvironment. This optimizes degradation performance while ensuring the bioactivity of growth factors, achieving a dynamic match between the material's mechanical properties and healing function.

[0053] The preparation process of this invention integrates PGA / SF blend spinning and growth factor oscillation impregnation technology, which can rapidly and efficiently release growth factors and promote wound healing.

[0054] The absorbable wound hemostatic membrane with antibacterial function prepared by this invention has the following specific characteristics:

[0055] 1. Intelligent degradation matching: This invention achieves precise synchronization between the degradation cycle and the dermal tissue regeneration stage through material ratio optimization, providing continuous mechanical support during the critical stage of wound repair.

[0056] 2. Adjustable structural characteristics: By adjusting the electrospinning parameters, this invention can obtain wound suture membranes with different fiber diameters and pore structures, thereby meeting the needs of different wound types and clinical applications.

[0057] 3. Enhanced bioactivity: This invention successfully loads growth factors onto the surface of a fibrous membrane through oscillation infiltration, which can promote wound healing in the first instance. Experiments have shown that it can effectively promote the construction of microvascular networks.

[0058] 4. Enhanced mechanical properties: The unique structural design of this invention enables the material's mechanical strength to break through the limitations of traditional biomembrane materials, fully meeting the clinical mechanical requirements for deep tissue repair.

[0059] 5. Enhanced tissue compatibility: The natural components of this invention significantly improve cell compatibility and promote rapid migration of basal cells and regeneration of extracellular matrix in wounds.

[0060] 6. Clinical adaptation optimization: The material of this invention combines ideal flexibility with stability in the body fluid environment, ensuring the reliability of intraoperative operation and the integrity of the suture interface.

[0061] 7. Production controllability: The continuous preparation process of this invention achieves highly uniform product performance and has the technical and economic advantages of large-scale production.

[0062] In summary, this invention has achieved significant improvements in healing promotion, hemostasis, biocompatibility, structural controllability, and industrial production, providing an innovative solution for the development of high-performance wound suture materials.

[0063] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the invention and to implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Specific embodiments of the present invention are given in detail below with reference to the accompanying drawings. Attached Figure Description

[0064] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0065] Figure 1 These are physical images of the amorphous PGA films obtained after pressure heat treatment of PGA in Examples 1, 2 and 3 of this invention;

[0066] Figure 2 The images show the final physical images of the SF freeze-dried powder obtained in Examples 1, 2 and 3 of this invention, with each bottle containing 0.3g of SF freeze-dried powder.

[0067] Figure 3 This is a photograph of the PGA / SF composite electrospun film prepared in Example 1 of the present invention under the condition of a PGA / SF mass ratio of 7:3;

[0068] Figure 4 This is a 2000x SEM image of the PGA / SF composite electrospun film prepared in Example 1 of the present invention under the condition of a PGA / SF mass ratio of 7:3. Detailed Implementation

[0069] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings to provide a clearer understanding of the invention's purpose, features, and advantages. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the invention, but are merely illustrative of the essential spirit of the invention's technical solution.

[0070] In the following description, certain specific details are set forth for the purpose of illustrating various disclosed embodiments in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments may be practiced without one or more of these specific details. In other instances, well-known apparatuses, structures, and techniques associated with this application may not have been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0071] Unless the context requires otherwise, throughout the specification and claims, the word “comprising” and its variations, such as “including” and “having”, shall be understood to have an open, inclusive meaning, that is, to be interpreted as “including, but not limited to”.

[0072] Throughout this specification, references to "an embodiment" or "an embodiment" indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Therefore, the appearance of "in an embodiment" or "an embodiment" in various places throughout the specification does not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, or characteristic may be combined in any manner in one or more embodiments.

[0073] The singular forms “a” and “the” used in this specification and the appended claims include plural references unless otherwise expressly stated herein. It should be noted that the term “or” is generally used to mean “and / or” unless otherwise expressly stated herein.

[0074] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0075] This invention provides a method for preparing an absorbable wound suture membrane with healing-promoting properties, specifically including the following steps:

[0076] Step 1) Pressure heat treatment of PGA raw material:

[0077] Polyglycolic acid (PGA) particles with a molecular weight of 12–18 kDa and a viscosity of 1.2–1.7 dL / g were selected as one of the raw materials, and pressure heat treatment was carried out on them using a hot pressing-quenching process to eliminate crystallization, thereby preparing an amorphous PGA film with significantly improved solubility and processing performance.

[0078] Preferably, the pressure heat treatment employs a hot-pressing-liquid nitrogen quenching method, which eliminates the crystal structure of the polyglycolic acid through the principle of heating first and then cooling, thereby significantly improving the solubility and processing performance of the material. The specific method is as follows:

[0079] PGA particles are placed in a hot pressing device and hot-pressed for 30 to 60 seconds at a temperature of 40 to 260°C and a pressure of 2 to 5 MPa. After hot pressing, the PGA film is quickly transferred to a liquid nitrogen environment for quenching for 1 to 2 minutes to obtain an amorphous PGA film.

[0080] The crystallinity of the amorphous PGA film obtained after pressure heat treatment is significantly reduced, while its solubility and processability are significantly improved.

[0081] Step 2) Preparation of SF freeze-dried powder:

[0082] A suitable amount of silkworm cocoons were selected as one of the raw materials, and after being degummed, dissolved, washed, purified and dried, lyophilized silk fibroin (SF) powder was obtained.

[0083] Preferably, the specific method for preparing the SF lyophilized powder is as follows:

[0084] Weigh a certain amount of silkworm cocoons and cut them into small pieces. First, degumming is performed using a sodium carbonate degumming process. Specifically, the cut cocoons are placed in a 0.5%–1 wt% sodium carbonate solution and treated at 90–100°C for 30–60 minutes to remove sericin and impurities from the silk surface. Then, the degummed silk is repeatedly washed with deionized water 5–8 times to remove residual sericin and alkali. The washed degummed silk is then placed in a ventilated area and allowed to air dry naturally for 24 hours at 25°C and 50%–60% relative humidity. Next, the degummed silk is dissolved using a lithium bromide dissolution process. Specifically, the dried degummed silk fibers are immersed in a 9–10 mol / L lithium bromide solution and heated at 50–80°C for 4 hours. For 6 hours, the silk fibers are fully dissolved to obtain an SF solution. Then, the SF solution is purified using dialysis. Specifically, the obtained SF solution is placed in a dialysis bag with a molecular weight cutoff of 2000-4000 Da and dialyzed for 60-80 hours, with the dialysate replaced every 8 hours to remove small molecule impurities, thus obtaining a clear SF solution. The clear SF solution is then diluted to a concentration of 3-5 wt%, and a 5-8% phosphate buffer solution with a pH of 7.4 is added to adjust the pH and stability of the SF solution. Finally, the purified SF solution is dispensed into vials, flash-frozen in liquid nitrogen, and then freeze-dried in a freeze dryer for 50-80 hours to obtain SF freeze-dried powder with a purity of over 95%.

[0085] Step 3) Preparation of PGA / SF composite electrospinning solution:

[0086] Hexafluoroisopropanol (HFIP) was selected as the solvent, and the amorphous PGA film and the lyophilized SF powder were mixed in HFIP at a certain mass ratio to prepare the PGA / SF composite electrospinning solution.

[0087] Preferably, the specific method for preparing the PGA / SF composite electrospinning solution can be as follows:

[0088] First, weigh a certain amount of the prepared amorphous PGA membrane and add it to HFIP solvent to prepare a PGA solution. Then, place the prepared PGA solution in a constant temperature water bath at 60-80℃ and heat and stir for 6-8 hours until the amorphous PGA membrane is completely dissolved to form a uniform and transparent PGA electrospinning solution. Finally, add SF freeze-dried powder to the PGA electrospinning solution at a certain mass ratio and stir at room temperature for 12-14 hours to fully disperse the SF freeze-dried powder in the PGA electrospinning solution, thereby obtaining a semi-transparent milky white PGA / SF composite electrospinning solution.

[0089] Preferably, the specific method for preparing the PGA / SF composite electrospinning solution can also be as follows:

[0090] According to a certain mass ratio, accurately weigh the amorphous PGA membrane and SF lyophilized powder; add the weighed amorphous PGA membrane and SF lyophilized powder together to hexafluoroisopropanol to prepare a mixed solution; place the prepared mixed solution in a constant temperature water bath at 40-50℃ and heat and stir for 8-10 hours until the amorphous PGA membrane and SF lyophilized powder are completely dissolved to obtain a stable and semi-transparent milky white PGA / SF composite electrospinning solution.

[0091] Preferably, the specific method for preparing the PGA / SF composite electrospinning solution can also be as follows:

[0092] A certain amount of the prepared amorphous PGA membrane was weighed and added to hexafluoroisopropanol (HFIP) to prepare a PGA solution. The prepared PGA solution was placed in a constant temperature water bath at 60-80℃ and heated and stirred for 6-8 hours until the amorphous PGA membrane was completely dissolved, thus obtaining a uniform and transparent PGA electrospinning solution. A certain amount of the prepared SF lyophilized powder was weighed and dissolved in a formic acid / water mixed solvent to prepare an SF solution. The solution was then ultrasonically treated for 30-50 minutes to degas the solution, ensuring that the SF solution was uniform and free of bubbles. The PGA electrospinning solution and the SF solution were mixed at a mass ratio, and the emulsifier Tween-80 was added. The solution was ultrasonically treated for 5-8 minutes under ice bath conditions to form a stable oil-in-water emulsion, thus obtaining a semi-transparent milky white PGA / SF composite electrospinning solution.

[0093] Step 4) Load the prepared PGA / SF composite electrospinning solution into a syringe and connect it to the electrospinning equipment. After initially setting the spinning parameters, start electrospinning. During the spinning process, adjust the spinning parameters to obtain a nanofiber membrane with a diameter of 200-800 nm, i.e., a PGA / SF composite electrospinned membrane.

[0094] Preferably, the spinning parameters include spinning voltage, collection distance, liquid feeding speed, ambient temperature, and ambient humidity.

[0095] Before starting electrospinning, the initial settings are as follows: spinning voltage 10–25 kV, collection distance 12–20 cm, liquid feeding rate 0.5–1.5 mL / h, ambient humidity 20–30 °C, and ambient temperature 25%–40% RH.

[0096] During electrospinning, the spinning voltage was optimized to 16–20 kV, the collection distance to 14–20 cm, the liquid feeding rate to 0.5–1.5 mL / h, the ambient humidity to 20–30 °C, and the ambient temperature to 25%–40% RH.

[0097] Step 5) Using the low-temperature oscillation method, coaxial electrospinning method, or ternary electrospinning method, the active factor is loaded onto the prepared PGA / SF composite electrospinning membrane to obtain the PGA / SF / active factor ternary composite electrospinning membrane, which is a wound suture membrane with absorbable healing function.

[0098] The specific procedure for the low-temperature oscillation method is as follows:

[0099] The prepared polyglycolic acid / silk fibroin composite electrospun membrane was placed in a basic fibroblast growth factor (bFGF) solution with a concentration gradient of 20–100 μg / mL and subjected to shaking immersion at 2–6℃ for 4–48 hours to allow the basic fibroblast growth factor to be fully adsorbed on the fiber surface and inside the polyglycolic acid / silk fibroin composite electrospun membrane, thereby obtaining a polyglycolic acid / silk fibroin / active factor ternary composite electrospun membrane.

[0100] The specific procedure for the coaxial electrospinning method is as follows:

[0101] Selected vascular endothelial growth factor (VEGF) 165 As the active ingredient, lyophilized VEGF powder and bovine serum albumin (BSA) protectant were dissolved together in PBS buffer to prepare a BSA-VEGF complex. A certain amount of BSA-VEGF complex and polyvinyl alcohol (PVA) were weighed, and an appropriate amount of PBS buffer was added. The mixture was stirred in a low-temperature magnetic stirrer at 3-6°C for 4-5 hours to ensure uniform dispersion, thus obtaining a core-layer drug-loaded solution. Based on step 4, the PGA / SF composite electrospinning solution was loaded into one syringe and connected to the shell channel of a coaxial nozzle via a conduit. The core-layer drug-loaded solution was loaded into another syringe and connected to the shell channel of a coaxial nozzle via a conduit. The core-shell channels of the spinneret are connected. After initially setting the spinning parameters, coaxial electrospinning begins. The PGA / SF composite electrospinning solution forms the shell nanofibers, and the core-shell drug-loaded solution forms the core nanofibers. By adjusting the spinning parameters during the coaxial spinning process, a nanofiber membrane with a core-shell structure, namely the PGA / SF / VEGF ternary composite electrospinned membrane, is obtained. After spinning, the obtained PGA / SF / VEGF ternary composite electrospinned membrane is immediately placed in a dry place to remove residual solvent. Then, glutaraldehyde vapor is used for crosslinking for 2-4 hours, and the staged release of VEGF is achieved by controlling the degree of crosslinking.

[0102] The specific procedure for the ternary electrospinning method is as follows:

[0103] Basic fibroblast growth factor (bFGF) was dissolved in PBS buffer to prepare a bFGF solution. This bFGF solution was then slowly added to the PGA / SF composite electrospinning solution, and the mixture was gently stirred for 30–40 min to complete the bFGF loading, thus obtaining the PGA / SF / bFGF ternary composite electrospinning solution. The prepared PGA / SF / bFGF ternary composite electrospinning solution was injected into a syringe and connected to the corresponding needle of the electrospinning equipment. The syringe was then allowed to stand for a period of time until air bubbles disappeared. After setting the initial spinning conditions, ternary electrospinning was initiated. In the electrospinning process, the fiber formation process is controlled by adjusting the electric field strength and spinning distance, ultimately producing a nanofiber membrane with uniform thickness, low orientation, and no beading, namely a PGA / SF / bFGF ternary composite electrospinned membrane. The obtained PGA / SF / bFGF ternary composite electrospinned membrane is exposed in a 75% ethanol atmosphere for 12-14 hours to enhance SF stability, and then dried at 40°C for one day to remove residual solvent. Finally, it is sterilized by gamma irradiation to ensure the sterility of the material, and finally a wound suture membrane with absorbable and healing-promoting functions is obtained.

[0104] Based on the above preparation method, the present invention also provides a wound suture membrane with absorbable healing-promoting function prepared by the above preparation method.

[0105] The following details three preferred embodiments of the present invention.

[0106] Example 1

[0107] Step 1) Pressure heat treatment of PGA raw material:

[0108] Polyglycolic acid (PGA) particles with a molecular weight of 12–18 kDa and a viscosity of 1.2–1.7 dL / g were selected as one of the raw materials and amorphized using a hot-pressing-liquid nitrogen quenching method. The specific procedure was as follows: First, the flat vulcanizing apparatus was preheated to 240–260℃. Then, a certain amount of PGA particles was accurately weighed and evenly spread on the surface of a 20cm × 20cm polyimide film (the spreading thickness was controlled between 1–2 mm). Another layer of polyimide film was then placed directly on top of the PGA particles, forming a "sandwich" structure of polyimide film-PGA-polyimide film, ensuring that the PGA particles could be immediately removed for liquid nitrogen quenching after hot pressing. Next, the two layers of polyimide film were placed in the preheated flat vulcanizing apparatus and hot-pressed at a pressure of 2–5 MPa for approximately 30 seconds. During the hot pressing process, the pressure was monitored in real time using a pressure sensor to ensure that the pressure remained stable within the set range. After hot pressing, the sample is immediately removed from the flat vulcanizing apparatus and quickly quenched in liquid nitrogen solution for 1-2 minutes. After quenching, the polyimide film is carefully peeled off to obtain the desired result. Figure 1 The amorphous PGA membrane shown.

[0109] This pressure heat treatment process significantly improves the solubility and processing properties of PGA by altering its molecular arrangement. The amorphous PGA film obtained in this embodiment, after treatment under optimal hot-pressing and liquid nitrogen quenching conditions, exhibits excellent solubility, completely dissolving in hexafluoroisopropanol (HFIP) solution under heating and stirring conditions, providing an ideal raw material basis for subsequent spinning.

[0110] Step 2) Preparation of SF freeze-dried powder:

[0111] First, take 30g of silkworm cocoons and cut them into uniform small segments, each approximately 0.5–1cm in length. Then, place them in 12L of boiling water containing 20–30g of Na2CO3 for degumming for 30–45 minutes. After degumming, repeatedly wash the cocoons with deionized water 5–8 times to remove residual sericin and alkali. Then, place the washed and degummed silk in a ventilated area and allow it to air dry naturally for 24 hours at 25℃ and 50%–60% relative humidity. Immerse the dried degummed silk fibers in approximately 100mL of a 9–10mol / L lithium bromide (LiBr) solution and heat at 50–80℃ for 4–6 hours to fully dissolve the silk fibers. The resulting solution is then placed in a dialysis bag with a molecular weight cutoff of 2000–4000 Da for dialysis for 70–80 hours, changing the dialysis solution every 8 hours to thoroughly remove small molecule impurities from the solution. After filtration of the dialysate, a clear silk fibroin (SF) solution was obtained. The SF solution was diluted to a concentration of 3–5 wt%, and 5–8% phosphate buffer (pH 7.4) was added to adjust the pH and stability of the solution. Finally, the SF solution was dispensed into vials (6–10 mL / vial), flash-frozen in liquid nitrogen, and then freeze-dried in a freeze dryer for 60–80 hours to obtain the desired product. Figure 2 The SF freeze-dried powder shown has a purity of 96.5%.

[0112] Figure 2 Each bottle contains 0.3g of SF lyophilized powder. After weighing the SF lyophilized powder, it is placed in a PGA solution and stirred for 12 hours to obtain a PGA / SF composite electrospinning solution.

[0113] Step 3) Preparation of PGA / SF composite electrospinning solution:

[0114] A certain amount of amorphous PGA membrane was weighed and added to hexafluoroisopropanol (HFIP) to prepare a PGA solution with a concentration of 8–12% (w / v). The PGA solution was heated and stirred in a constant temperature water bath at 60–80℃ for 6–8 hours. During the stirring process, a magnetic stirrer was used to stir thoroughly at a speed of 500–600 r / min until the amorphous PGA membrane was completely dissolved, forming a uniform and transparent PGA electrospinning solution. Then, lyophilized SF powder was added to the PGA electrospinning solution in a gradient of PGA:SF mass ratios of 7:3, 5:5, and 3:7. The solution was stirred at room temperature using a magnetic stirrer at a speed of 300–400 r / min for 12–14 hours to ensure that the lyophilized SF powder was fully dispersed in the PGA electrospinning solution, resulting in a stable and semi-transparent milky white PGA / SF composite electrospinning solution (viscosity between 1.2 and 1.8 Pa·s).

[0115] Step 4) Preparation of PGA / SF composite electrospun film:

[0116] The prepared PGA / SF composite electrospinning solution was injected into a 20 mL syringe and connected to a No. 17 needle (0.84 mm inner diameter) of the electrospinning equipment. The initial spinning parameters were set as follows: spinning voltage 15–25 kV, collection distance 12–20 cm, feeding rate 0.5–1.5 mL / h, ambient temperature 20–30 °C, and ambient humidity 25%–40% RH. Electrospinning was performed under these parameters. During electrospinning, the fiber formation process was controlled by adjusting the electric field strength and spinning distance. Finally, under the conditions of a spinning voltage of 16–10 kV and a collection distance of 14–20 cm, nanofiber membranes with fiber diameters of 200–800 nm were successfully prepared. Figure 3 The PGA / SF composite electrospun film shown.

[0117] See Figure 4 As shown, observation of 2000x scanning electron microscopy (SEM) images revealed that the PGA / SF composite electrospun membrane prepared under these conditions exhibited a uniform fiber distribution and displayed two fiber states: coarse PGA fibers and fine SF fibers, with virtually no beading, demonstrating good fiber morphology and achieving the effect of dual-gradient electrospinning. Furthermore, statistical analysis showed that the average fiber diameter of the prepared PGA / SF composite electrospun membrane was 500 nm, with a standard deviation of 100 nm, indicating a relatively uniform fiber diameter distribution. This nanofiber membrane possesses a large specific surface area and a three-dimensional nanofiber network structure, providing an excellent carrier for subsequent growth factor loading.

[0118] Step 5) Loading of active factors:

[0119] A basic fibroblast growth factor (bFGF) solution with a concentration gradient of 20–100 μg / mL was used for shaking infiltration at 4°C for 4–24 hours, with the shaking frequency controlled within the range of 50–150 rpm. PGA / SF composite electrospun membranes (1 cm × 1 cm) were placed in containers containing different concentrations of bFGF solution (5 mL volume). Shaking was used to ensure that bFGF was fully adsorbed onto the fiber surface and interior of the PGA / SF composite electrospun membrane (achieving a loading efficiency of over 85%), thus obtaining a PGA / SF / bFGF ternary composite electrospun membrane, i.e., an absorbable wound suture membrane with healing-promoting function. The release kinetics of bFGF were systematically studied, and the optimal loading conditions were determined by periodically monitoring the concentration changes of bFGF in the solution.

[0120] This embodiment prepared an absorbable, healing-promoting suture membrane based on a PGA / SF / bFGF ternary composite system. An absorbable and biodegradable film was prepared using electrospinning technology, and then successfully loaded with growth factors by immersion in a bFGF solution, meeting the functional requirements for promoting healing. Using PGA as the matrix, its degradation cycle (4-6 weeks) highly matches the epidermal-dermal healing stage, and the degradation rate can be precisely adjusted by controlling the molecular weight (Mw = 50-100 kDa). Silk fibroin (SF) was introduced as a second phase, utilizing its amphiphilic structure (containing Gly-Ala repeat sequences in the hydrophilic region and β-sheet crystals in the hydrophobic region) to achieve molecular-level compatibility with PGA. A covalent cross-linked network was constructed through an amidation reaction, improving the tensile strength of the composite fiber. Finally, the electrospun membrane was placed in a bFGF solution and subjected to oscillation wetting at a certain temperature, successfully loading bioactive factors. In addition, different ratios of PGA / SF solution can flexibly adjust the degradation rate of wound suture membrane, and different electrospinning process parameters can also adjust properties such as thickness and pore size to meet different wound care needs.

[0121] Compared to traditional suture membranes, the PGA / SF / bFGF absorbable wound healing suture membrane exhibits multidimensional innovative advantages. Its nanofiber network, constructed through electrospinning technology, not only rapidly absorbs wound exudate to form a physical barrier, but the synergistic effect of PGA and SF also activates platelet aggregation pathways, achieving highly efficient hemostasis. The inherent β-sheet structure of SF provides a stable, sustained-release carrier for bFGF growth factors, continuously stimulating fibroblast proliferation and angiogenesis. Simultaneously, the natural RGD sequence of SF significantly enhances cell adhesion, and combined with the epithelialization-promoting effect of bFGF, increases collagen deposition rate by over 40%. By controlling the ratio of PGA to SF, the material system achieves precise matching between degradation cycle and tissue regeneration process (gradual degradation over 2–4 weeks), with no inflammatory reaction from degradation products. Compared to traditional suture materials, this membrane combines mechanical support (tensile strength ≥8 MPa) with flexible adhesion, and the adjustable electrospinning process parameters facilitate large-scale production, demonstrating significant clinical translational value in the fields of acute wound suturing and chronic wound repair.

[0122] Example 2

[0123] Step 1) Pressure heat treatment of PGA raw material:

[0124] Polyglycolic acid (PGA) particles with a molecular weight of 12–18 kDa and a viscosity of 1.2–1.7 dL / g were selected as one of the raw materials and amorphized using a hot-pressing-liquid nitrogen quenching method. The specific procedure is as follows: First, the flat vulcanizing apparatus is preheated to 240–260℃. Then, a certain amount of PGA particles is accurately weighed and evenly spread on the surface of a 20cm × 20cm polyimide film (the spreading thickness is controlled between 1–2 mm). Next, another layer of polyimide film is placed directly on top of the PGA particles, forming a "sandwich" structure of polyimide film-PGA-polyimide film, ensuring that the PGA particles can be immediately removed for liquid nitrogen quenching after hot pressing. Then, the two layers of polyimide film are placed in the preheated flat vulcanizing apparatus and hot-pressed at a pressure of 2–5 MPa for approximately 30–60 seconds. During the hot pressing process, the pressure is monitored in real time using a pressure sensor to ensure that the pressure remains stable within the set range. After hot pressing, the sample is immediately removed from the flat vulcanizing apparatus and quickly quenched in liquid nitrogen solution for 1-2 minutes. After quenching, the polyimide film is carefully peeled off to obtain the desired result. Figure 1 The amorphous PGA membrane shown.

[0125] This pressure heat treatment process significantly improves the solubility and processing properties of PGA by altering its molecular arrangement. The amorphous PGA film obtained in this embodiment, after treatment under optimal hot-pressing and liquid nitrogen quenching conditions, exhibits excellent solubility, completely dissolving in hexafluoroisopropanol (HFIP) solution under heating and stirring conditions, providing an ideal raw material basis for subsequent spinning.

[0126] Step 2) Preparation of SF freeze-dried powder:

[0127] First, take 30g of silkworm cocoons and cut them into uniform small segments, each approximately 0.5–1cm in length. Then, place them in 12L of boiling water containing 20–30g of Na2CO3 for degumming for 30 minutes. After degumming, repeatedly wash the cocoons with deionized water 5–8 times to remove residual sericin and alkali. Then, place the washed and degummed silk in a ventilated area and allow it to air dry naturally for 24 hours at 25℃ and 50%–60% relative humidity. Immerse the dried degummed silk fibers in approximately 100mL of a 9–10mol / L lithium bromide (LiBr) solution and heat at 50–80℃ for 4–6 hours to fully dissolve the silk fibers. The resulting solution is then placed in a dialysis bag with a molecular weight cutoff of 2000–4000 Da for dialysis for 60–80 hours, changing the dialysis solution every 8 hours (500mL each time) to thoroughly remove small molecule impurities from the solution. After filtration of the dialysate, a clear silk fibroin (SF) solution was obtained. The SF solution was diluted to a concentration of 3–5 wt%, and 5–8% phosphate buffer (pH 7.4) was added to adjust the pH and stability of the solution. Finally, the SF solution was dispensed into vials (6–10 mL / vial), flash-frozen in liquid nitrogen, and then freeze-dried in a freeze dryer for 50–70 hours to obtain the desired product. Figure 2 The SF freeze-dried powder shown has a purity of 96.5%.

[0128] Figure 2 Each bottle contains 0.3g of SF lyophilized powder. After weighing the SF lyophilized powder, it is placed in a PGA solution and stirred for 12 hours to obtain a PGA / SF composite electrospinning solution.

[0129] Step 3) Preparation of PGA / SF composite electrospinning solution:

[0130] First, accurately weigh 36g of amorphous PGA membrane and 24g of SF lyophilized powder according to a mass ratio of 6:4. Then, add the weighed amorphous PGA membrane and SF lyophilized powder together to hexafluoroisopropanol (HFIP) to prepare a mixed solution with a total concentration of 12-18%. Finally, place the mixed solution in a constant temperature water bath at 40-50℃ and heat and stir for 8-10 hours. During the stirring process, use a magnetic stirrer at a speed of 500-600 r / min to stir thoroughly until the amorphous PGA membrane and SF lyophilized powder are completely dissolved, obtaining a stable and semi-transparent milky white PGA / SF composite electrospinning solution (viscosity between 1.2 and 1.8 Pa·s).

[0131] Step 4) Construction of the core-layer drug delivery system:

[0132] Selected vascular endothelial growth factor (VEGF) 165 As the active ingredient, lyophilized VEGF powder was dissolved together with 0.5–1% bovine serum albumin (BSA) protectant in PBS buffer at pH 7–8 to prepare the BSA-VEGF complex. 0.5–2 g of the prepared BSA-VEGF complex and 7–10 g of polyvinyl alcohol (PVA) were accurately weighed and added to an appropriate amount of PBS buffer at pH 7–8. The mixture was stirred at 300–400 rpm for 4–5 hours in a low-temperature magnetic stirrer at 3–6°C to ensure uniform dispersion. The BSA-VEGF complex and PVA were then mixed at a mass ratio of 1:9 to prepare a core-layer drug-loaded solution with a total concentration of 6–10%.

[0133] Step 5) Coaxial electrospinning of the PGA / SF composite electrospinning solution and the core-layer drug loading solution:

[0134] A dual-channel injection pump is used, with one syringe injecting the PGA / SF composite electrospinning solution and the other injecting the core-layer drug-loaded solution. The syringe containing the PGA / SF composite electrospinning solution is connected to the shell channel of the coaxial nozzle via a catheter, and the syringe containing the core-layer drug-loaded solution is connected to the core channel of the coaxial nozzle. The positive terminal of the high-voltage power supply is connected to the coaxial nozzle, and the negative terminal is connected to the receiving device (such as aluminum foil). The flow rate ratio of the shell (PGA / SF) to the core (PVA-VEGF) is set to 3:1, and a 22G coaxial needle (0.4 mm inner diameter / 0.7 mm outer diameter) is used. Under ambient temperatures of 28±2℃ and humidity of 35±3%RH, coaxial electrospinning was performed with a spinning voltage of 18–22 kV, a receiving distance of 16–20 cm, and a feeding rate of 1.2 mL / h. Specifically, an injection pump fed the PGA / SF composite electrospinning solution and the core-layer drug-loaded solution into the shell and core-layer channels of the coaxial nozzle at the set feeding rates. Simultaneously, a high-voltage power supply was turned on. Under the influence of the electric field, the PGA / SF composite electrospinning solution and the core-layer drug-loaded solution formed a Taylor cone at the end of the coaxial nozzle. As the PGA / SF composite electrospinning solution and the core-layer drug-loaded solution were continuously ejected, the solvent evaporated, and PGA / SF and PVA-VEGF formed shell and core-layer nanofibers, respectively, which were deposited on the receiving device to form a nanofiber membrane with a core-shell structure, namely, a PGA / SF / VEGF ternary composite electrospinned membrane. Scanning electron microscopy characterization showed that the prepared nanofiber membrane had uniform fiber diameter and continuous fibers with a complete core-shell structure.

[0135] Step 6) VEGF activity protection and sustained-release regulation:

[0136] Immediately after spinning, the obtained PGA / SF / VEGF ternary composite electrospun membrane was placed in a vacuum drying oven (40–50℃, -0.1–0 MPa) for 6–8 hours to remove residual solvent. Then, it was crosslinked with 0.2–0.5% glutaraldehyde vapor for 2–4 hours. By controlling the degree of crosslinking, the VEGF was released in stages, and finally, an absorbable wound suture membrane with healing-promoting function was obtained.

[0137] Example 3

[0138] Step 1) Pressure heat treatment of PGA raw material:

[0139] Polyglycolic acid (PGA) particles with a molecular weight of 12–18 kDa and a viscosity of 1.2–1.7 dL / g were selected as one of the raw materials and amorphized using a hot-pressing-liquid nitrogen quenching method. The specific procedure is as follows: First, the flat vulcanizing apparatus is preheated to 240–260℃. Then, a certain amount of PGA particles is accurately weighed and evenly spread on the surface of a 20cm × 20cm polyimide film (the spreading thickness is controlled between 1–2 mm). Next, another layer of polyimide film is placed directly on top of the PGA particles, forming a "sandwich" structure of polyimide film-PGA-polyimide film, ensuring that the PGA particles can be immediately removed for liquid nitrogen quenching after hot pressing. Then, the two layers of polyimide film are placed in the preheated flat vulcanizing apparatus and hot-pressed at a pressure of 2–5 MPa for approximately 30–60 seconds. During the hot pressing process, the pressure is monitored in real time using a pressure sensor to ensure that the pressure remains stable within the set range. After hot pressing, the sample is immediately removed from the flat vulcanizing apparatus and quickly quenched in liquid nitrogen solution for 1-2 minutes. After quenching, the polyimide film is carefully peeled off to obtain the desired result. Figure 1 The amorphous PGA membrane shown.

[0140] This pressure heat treatment process significantly improves the solubility and processing properties of PGA by altering its molecular arrangement. The amorphous PGA film obtained in this embodiment, after treatment under optimal hot-pressing and liquid nitrogen quenching conditions, exhibits excellent solubility, completely dissolving in hexafluoroisopropanol (HFIP) solution under heating and stirring conditions, providing an ideal raw material basis for subsequent spinning.

[0141] Step 2) Preparation of SF freeze-dried powder:

[0142] First, take 30-50g of silkworm cocoons and cut them into even pieces, each about 0.5-1cm in length. Then, place them in 12-18L of boiling water containing 20-30g of Na2CO3 for degumming for 30-60 minutes. During degumming, use an electric stirrer at 200-300 rpm to ensure the cocoons are in full contact with the alkaline solution and to ensure effective degumming. After degumming, repeatedly wash the cocoons with deionized water 5-8 times to remove residual sericin and alkaline solution. Then, place the washed and degummed silk in a ventilated area and allow it to air dry naturally for 24 hours at 25℃ and 50%-60% relative humidity. Immerse the dried degummed silk fibers in about 100-150mL of 9-10mol / L LiBr solution and heat at 50-70℃ for 4-6 hours to fully dissolve the silk fibers. The obtained solution was placed in a dialysis bag with a molecular weight cutoff of 2000–4000 Da for dialysis for 70–80 hours, with the dialysate replaced every 8 hours to thoroughly remove small molecule impurities. After filtration, a clear silk fibroin (SF) solution was obtained. The SF solution was diluted to a concentration of 3–5 wt%, and 5–8% phosphate buffer (pH 7.4) was added to adjust the pH and stability of the solution. Finally, the SF solution was dispensed into vials (6–10 mL / vial), flash-frozen in liquid nitrogen, and then freeze-dried in a freeze dryer for 60–80 hours to obtain the desired product. Figure 2 The SF freeze-dried powder shown has a purity of 96.5%.

[0143] Figure 2 Each bottle contains 0.3g of SF lyophilized powder. After weighing the SF lyophilized powder, it is placed in a PGA solution and stirred for 12 hours to obtain a PGA / SF composite electrospinning solution.

[0144] Step 3) Preparation of PGA / SF composite electrospinning solution:

[0145] Weigh a certain amount of amorphous PGA membrane and add it to hexafluoroisopropanol (HFIP) to prepare a PGA solution with a concentration of 8-12% (w / v). Place the PGA solution in a constant temperature water bath at 60-80℃ and heat and stir for 6-8 hours. During stirring, use a magnetic stirrer at a speed of 500-600 r / min to stir thoroughly until the amorphous PGA membrane is completely dissolved, obtaining a uniform and transparent PGA electrospinning solution. Store the PGA electrospinning solution in a sealed container away from light to prevent deterioration.

[0146] Weigh a certain amount of SF lyophilized powder and dissolve it in a formic acid / water mixed solvent (volume ratio 7:3) to prepare an SF solution with a concentration of 10-15% (w / v). Degas the solution by ultrasonic treatment for 30-50 minutes with an ultrasonic power of 200-300W to ensure that the SF solution is uniform and free of bubbles.

[0147] The PGA electrospinning solution and SF solution were mixed at a mass ratio of 7:3 to 5:5, and 0.5 to 1% Tween-80 was added as an emulsifier. The mixture was then subjected to ultrasonic treatment (200 to 300 W, 5 to 8 min) under ice bath conditions to form a stable oil-in-water emulsion, thus obtaining a translucent, milky-white PGA / SF composite electrospinning solution (viscosity between 1.2 and 1.8 Pa·s).

[0148] Step 4) Preparation of PGA / SF / bFGF ternary composite electrospinning solution:

[0149] Basic fibroblast growth factor (bFGF) was dissolved in PBS buffer at pH 7.4 to prepare a bFGF solution of 1–3 mg / mL. The bFGF solution was then slowly added to the PGA / SF composite electrospinning solution to a final concentration of 50–100 ng / mL. The mixture was gently stirred magnetically (stirring speed <200 rpm) for 30–40 min to avoid protein inactivation. At this point, the bFGF loading was completed, and the PGA / SF / bFGF ternary composite electrospinning solution was prepared.

[0150] Step 5) Ternary electrospinning of the PGA / SF / bFGF ternary composite electrospinning solution:

[0151] The prepared PGA / SF / bFGF ternary composite electrospinning solution was injected into a 20 mL syringe and connected to the corresponding needle of the electrospinning equipment. The solution was then allowed to stand for a period of time until the air bubbles disappeared. The initial spinning parameters were set as follows: spinning voltage 18–25 kV, collection distance 12–18 cm, feeding rate 0.8–1.2 mL / h, ambient temperature 25 ± 2℃, and ambient humidity 30%–40% RH. Ternary electrospinning was performed under these parameters. During electrospinning, the fiber formation process was controlled by adjusting the electric field strength and spinning distance. Ultimately, a uniformly sized, low-orientation, bead-free nanofiber membrane, namely the PGA / SF / bFGF ternary composite electrospinned membrane, was successfully prepared.

[0152] Step 6) Post-processing and sterilization:

[0153] The prepared PGA / SF / bFGF ternary composite electrospun membrane was first exposed to a 75% ethanol atmosphere for 12–14 hours to enhance SF stability, and then dried at 40°C for one day to remove residual solvent. Finally, it was sterilized by gamma irradiation with an irradiation dose of 25–30 kGy to ensure the sterility of the material, ultimately yielding an absorbable wound suture membrane with healing-promoting properties.

[0154] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an absorbable wound suture membrane with healing-promoting function, characterized in that, Includes the following steps: Step 1) Select polyglycolic acid particles with a set molecular weight and viscosity as one of the raw materials, and subject them to pressure heat treatment to eliminate the crystalline structure, thereby preparing an amorphous polyglycolic acid film with significantly improved solubility and processing performance. Step 2) Select an appropriate amount of silkworm cocoons as one of the raw materials, and then perform degumming, dissolving, washing, purification and drying treatments on them in sequence to obtain silk fibroin freeze-dried powder; Step 3) Select hexafluoroisopropanol as solvent, and mix the prepared amorphous polyglycolic acid film and the prepared silk fibroin lyophilized powder in hexafluoroisopropanol according to a certain mass ratio to prepare a polyglycolic acid / silk fibroin composite electrospinning solution. Step 4) The prepared polyglycolic acid / silk fibroin composite electrospinning solution is loaded into a syringe and connected to an electrospinning device. After initially setting the spinning parameters, electrospinning begins. During the spinning process, the spinning parameters are adjusted to obtain a nanofiber membrane with a diameter of 200-800 nm, namely a polyglycolic acid / silk fibroin composite electrospinned membrane. Step 5) Using a low-temperature oscillation method, a coaxial electrospinning method, or a ternary electrospinning method, the active factor is loaded onto the prepared polyglycolic acid / silk fibroin composite electrospinned membrane to obtain a polyglycolic acid / silk fibroin / active factor ternary composite electrospinned membrane, which is a wound suture membrane with absorbable healing-promoting function.

2. The preparation method according to claim 1, characterized in that, In step 1, the molecular weight of the polyglycolic acid particles is 12-18 kDa, and the viscosity of the polyglycolic acid particles is 1.2-1.7 dL / g.

3. The preparation method according to claim 1, characterized in that, In step 1, the pressure heat treatment employs a hot-pressing-liquid nitrogen quenching method. By utilizing the principle of heating followed by cooling, the crystalline structure of the polyglycolic acid is eliminated, thereby significantly improving the material's solubility and processing performance. The specific procedure is as follows: Polyglycolic acid granules are placed in a hot press and hot-pressed for 30 to 60 seconds at a temperature of 40 to 260°C and a pressure of 2 to 5 MPa. After hot pressing, the polyglycolic acid film is quickly transferred to a liquid nitrogen environment for quenching for 1 to 2 minutes to obtain an amorphous polyglycolic acid film. The crystallinity of the amorphous polyglycolic acid film obtained after pressure heat treatment is significantly reduced, while its solubility and processability are significantly improved.

4. The preparation method according to claim 1, characterized in that, In step 2, the specific method for preparing the silk fibroin lyophilized powder is as follows: Weigh out a certain amount of silkworm cocoons and cut them into pieces; The degumming process is carried out using sodium carbonate. Specifically, the shredded silkworm cocoons are placed in a sodium carbonate solution and treated at 90-100℃ for 30-60 minutes to remove sericin and impurities from the surface of the silk. Wash the degummed silk repeatedly with deionized water 5 to 8 times to remove residual sericin and alkali. Then place the washed degummed silk in a ventilated place and let it air dry naturally for 24 hours at a temperature of 25°C and a relative humidity of 50% to 60%. The degummed silk was dissolved using a lithium bromide dissolution process. Specifically, the dried degummed silk fibers were immersed in a lithium bromide solution and heated at 50–80°C for 4–6 hours to fully dissolve the silk fibers and obtain a silk fibroin solution. The silk fibroin solution was purified by dialysis. Specifically, the prepared silk fibroin solution was placed in a dialysis bag with a molecular weight cutoff of 2000-4000 Da and dialyzed for 60-80 hours. The dialysis solution was replaced every 8 hours to remove small molecule impurities from the silk fibroin solution, thereby obtaining a clear silk fibroin solution. The clarified silk fibroin solution was diluted and phosphate buffer was added to adjust the pH and stability of the silk fibroin solution. The purified silk fibroin solution was dispensed into vials, flash-frozen in liquid nitrogen, and then freeze-dried in a freeze dryer for 50–80 hours to finally obtain a silk fibroin freeze-dried powder with a purity of over 95%.

5. The preparation method according to claim 1, characterized in that, In step 3, the specific method for preparing the polyglycolic acid / silk fibroin composite electrospinning solution is as follows: Weigh a certain amount of the prepared amorphous polyglycolic acid film and add it to hexafluoroisopropanol solvent to prepare a polyglycolic acid solution. Place the prepared polyglycolic acid solution in a constant temperature water bath at 60-80℃ and heat and stir for 6-8 hours until the amorphous polyglycolic acid film is completely dissolved to form a uniform and transparent polyglycolic acid electrospinning solution. Then add silk fibroin lyophilized powder to the polyglycolic acid electrospinning solution at a certain mass ratio and stir at room temperature for 12-14 hours to fully disperse the silk fibroin lyophilized powder in the polyglycolic acid electrospinning solution, and obtain a semi-transparent milky white polyglycolic acid / silk fibroin composite electrospinning solution. Alternatively, accurately weigh amorphous polyglycolic acid film and SF lyophilized powder according to a certain mass ratio; add the weighed amorphous polyglycolic acid film and silk fibroin lyophilized powder together to hexafluoroisopropanol to prepare a mixed solution; place the prepared mixed solution in a constant temperature water bath at 40-50℃ and heat and stir for 8-10 hours until the amorphous polyglycolic acid film and silk fibroin lyophilized powder are completely dissolved to obtain a stable and semi-transparent milky white polyglycolic acid / silk fibroin composite electrospinning solution; Alternatively, weigh a certain amount of the prepared amorphous polyglycolic acid film and add it to hexafluoroisopropanol to prepare a polyglycolic acid solution; place the prepared polyglycolic acid solution in a constant temperature water bath at 60-80℃ and heat and stir for 6-8 hours until the amorphous polyglycolic acid film is completely dissolved to obtain a uniform and transparent polyglycolic acid electrospinning solution; weigh a certain amount of the prepared lyophilized silk fibroin powder and dissolve it in a formic acid / water mixed solvent to prepare a silk fibroin solution; then sonicate for 30-50 minutes to degas to ensure that the silk fibroin solution is uniform and free of bubbles; mix the polyglycolic acid electrospinning solution and the silk fibroin solution according to the mass ratio, add the emulsifier Tween-80, and sonicate for 5-8 minutes under ice bath conditions to form a stable oil-in-water emulsion, thus obtaining a semi-transparent milky white polyglycolic acid / silk fibroin composite electrospinning solution.

6. The preparation method according to claim 1, characterized in that, In step 4, the spinning parameters include spinning voltage, collection distance, feeding speed, ambient temperature, and ambient humidity; wherein, Before electrospinning begins, the initial settings are as follows: spinning voltage 10–25 kV, collection distance 12–20 cm, liquid feeding rate 0.5–1.5 mL / h, ambient humidity 20–30 °C, and ambient temperature 25%–40% RH. During electrospinning, the spinning voltage was optimized to 16–20 kV, the collection distance to 14–20 cm, the liquid feeding rate to 0.5–1.5 mL / h, the ambient humidity to 20–30 °C, and the ambient temperature to 25%–40% RH.

7. The preparation method according to claim 1, characterized in that, In step 5, the specific implementation of the low-temperature oscillation method is as follows: The prepared polyglycolic acid / silk fibroin composite electrospun membrane was placed in an alkaline fibroblast growth factor solution with a concentration gradient of 20-100 μg / mL and subjected to shaking immersion at 2-6℃ for 4-48 hours to allow the alkaline fibroblast growth factor to be fully adsorbed on the fiber surface and inside the polyglycolic acid / silk fibroin composite electrospun membrane, thereby obtaining a polyglycolic acid / silk fibroin / active factor ternary composite electrospun membrane.

8. The preparation method according to claim 1, characterized in that, In step 5, the specific procedure for the coaxial electrospinning method is as follows: Vascular endothelial growth factor was selected as the active ingredient. The lyophilized vascular endothelial growth factor powder and bovine serum albumin protectant were dissolved together in PBS buffer to prepare the bovine serum albumin protectant-vascular endothelial growth factor complex. Weigh a certain amount of bovine serum albumin protectant-vascular endothelial growth factor complex and polyvinyl alcohol, add an appropriate amount of PBS buffer, and stir in a low-temperature magnetic stirrer at 3-6℃ for 4-5 hours to ensure uniform dispersion, thus obtaining a core layer drug loading solution. Based on step 4, the polyglycolic acid / silk fibroin composite electrospinning solution is loaded into a syringe and connected to the shell channel of the coaxial nozzle through a conduit. The core layer drug-loaded solution is loaded into another syringe and connected to the core layer channel of the coaxial nozzle through a conduit. After initially setting the spinning parameters, coaxial electrospinning was started. The polyglycolic acid / silk fibroin composite electrospinning solution formed the shell layer of nanofibers, and the core layer drug loading solution formed the core layer of nanofibers. By adjusting the spinning parameters during the coaxial spinning process, a nanofiber membrane with a core-shell structure was obtained, namely the polyglycolic acid / silk fibroin / active factor ternary composite electrospinned membrane. After spinning, the resulting polyglycolic acid / silk fibroin / active factor ternary composite electrospun membrane is immediately placed in a dry place to remove residual solvent; then, glutaraldehyde vapor is used for crosslinking for 2-4 hours, and the staged release of vascular endothelial growth factor is achieved by controlling the degree of crosslinking.

9. The preparation method according to claim 1, characterized in that, In step 5, the specific method of the ternary electrospinning process is as follows: Basic fibroblast growth factor was dissolved in PBS buffer to prepare an active factor solution. The active factor solution was slowly added to the polyglycolic acid / silk fibroin composite electrospinning solution and gently stirred for 30-40 minutes to complete the loading of basic fibroblast growth factor and obtain a polyglycolic acid / silk fibroin / active factor ternary composite electrospinning solution. The prepared polyglycolic acid / silk fibroin / active factor ternary composite electrospinning solution was injected into a syringe and connected to the corresponding needle of the electrospinning equipment. Then it was left to stand for a period of time until the bubbles disappeared. After setting the initial spinning conditions, ternary electrospinning begins. During the electrospinning process, the fiber formation process is controlled by adjusting the electric field strength and spinning distance. Finally, a nanofiber membrane with uniform thickness, low orientation, and no beading is produced, namely a polyglycolic acid / silk fibroin / active factor ternary composite electrospinned membrane. The prepared polyglycolic acid / silk fibroin / active factor ternary composite electrospun film was exposed in a 75% ethanol atmosphere for 12-14 hours to enhance the stability of silk fibroin, and then dried at 40°C for one day to remove residual solvent. Finally, gamma irradiation sterilization was used to ensure the sterility of the material, ultimately producing a wound suture membrane with absorbable healing-promoting function.

10. A wound suture membrane with absorbable healing-promoting function prepared by the preparation method according to any one of claims 1 to 9.

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