Preparation method and device of high-orientation-degree electrostatic spinning nanofiber absorbable surgical suture

Abstract

The invention discloses a preparation method of a high-orientation-degree electrostatic spinning nanofiber absorbable surgical suture. The preparation method comprises the following steps of (1) preparing a spinning solution, (2) preparing an orientation nanofiber bundle, (3) preparing a strip, (4) preparing a nanofiber line and (5) performing hot drawing treatment. Two conductive conveying belts which move in opposite directions are vertically and oppositely arranged below the electrostatic spinning nozzle in parallel, a receiving area used for adhering nanofibers which are consistent or similar in arrangement direction is formed between the two conductive conveying belts, and a whipping area is formed between the electrostatic spinning nozzle and the tops of the conductive conveying belts. The bottom of the receiving area is provided with a collecting plate which is used for intercepting the nanofibers adhered and fixed between the two conductive conveying belts and flatly laying, accumulating and stacking the nanofibers to form oriented nanofiber bundles. The nanofibers are arranged in the yarn in an ordered height orientation manner, and the mechanical property and the overall structural stability can be greatly improved under the condition of the same specification of yarn diameter.

Description

Technical Field

[0001] The invention belongs to the technical field of tissue engineering and biomanufacturing materials, and in particular relates to a preparation method and a device for a highly oriented electrostatically spun nanofiber absorbable surgical suture. Background Art

[0002] As we all know, medical materials have the characteristics of high added value. From the current market situation, since some high-end medical materials rely more on imports, they are usually priced relatively high. For China, it is urgent to develop a domestic high-end medical materials industry and obtain corresponding independent intellectual property rights.

[0003] Surgical sutures are an indispensable type of medical equipment in surgical operations. They are special threads used in surgical operations or trauma treatment for ligation and hemostasis, suture and tissue suture, and play a vital role in the early stages of wound healing. Common surgical sutures can be divided into non-absorbable sutures and absorbable sutures. The former need to be removed after surgery to prevent tissue infection, while the latter can be degraded in the body environment without secondary treatment, which greatly improves the patient experience and recovery effect. It is a major trend in the development of surgical sutures in the future. In order to meet the needs of surgical operations or trauma treatment, surgical suture fibers need to have the following properties:

[0004] 1. Mechanical properties: Sutures need to have good mechanical properties, including sufficient strength and toughness, to ensure that they will not break easily during surgery.

[0005] 2. Biocompatibility: Suture materials should be non-toxic and non-irritating, be well compatible with human tissues, and reduce inflammatory reactions and other adverse reactions.

[0006] 3. Absorbability: The sutures should gradually degrade over a certain period of time and eventually be absorbed by the human body to avoid secondary surgery for removal.

[0007] 4. Controllable drug release: For drug-loaded sutures, it is necessary to be able to achieve controlled drug release and release different doses of drugs according to different stages of wound healing.

[0008] At present, a large number of articles have shown that nano-scale fiber sutures have biological properties that traditional micron-scale fiber sutures lack, namely, they simulate the extracellular matrix structure and provide a good bionic microenvironment for cell activities, thereby effectively promoting cell adhesion, proliferation, migration and differentiation, and achieving rapid healing and regeneration of damaged tissues or wounds. It can be seen that the yarn obtained by twisting ultrafine fibers prepared by electrospinning technology can be made into high-strength and high-toughness sutures with good mechanical properties and biocompatibility, which can meet the basic requirements of surgical sutures. At present, the technology for preparing surgical sutures based on nanofiber yarns has made great progress, such as the following patents:

[0009] CN116808278A discloses a drug-loaded suture and a preparation method thereof, comprising a substrate and a drug loaded on the surface of the substrate; the substrate has a skin-core structure, and the core layer of the substrate is polylactic acid filaments; the skin layer of the substrate is a nanofiber membrane, and the nanofiber membrane is composed of polycaprolactone and polyglycolide; the mass percentage of the polyglycolide in the nanofiber membrane is 10 to 90%.

[0010] CN108193342A discloses a method for preparing a drug-loaded nanofiber core-spun yarn for absorbable surgical sutures, comprising adding antibacterial and anti-inflammatory drugs to a hexafluoroisopropanol solution of chitosan, silk fibroin, and polylactic acid, and mixing them evenly to form a spinning precursor; using a degradable surgical suture as the core yarn; and adopting an electrostatic spinning method to prepare a uniform and continuous drug-loaded nanofiber core-spun yarn. The present invention adopts an electrostatic spinning method to prepare a drug-loaded nanofiber core-spun yarn for surgical sutures, which has a simple process and is convenient to operate. The surface of the prepared yarn is evenly coated with nanofibers.

[0011] CN115839028A discloses an antibacterial surgical suture and its preparation method and application. The method uses amphiphilic molecules to encapsulate the fluorescent molecule DTPM with aggregation-induced emission characteristics to prepare AIE nanofibers; then, maleic anhydride on the surface of the nanofiber and the thiol reactive group on the cysteine ​​in the polypeptide sequence are subjected to addition reaction, and a bioactive polypeptide chain is introduced on the AIE nanofiber to prepare an AIE nanofiber with a positive charge and a hydrophilic surface structure; the surgical suture is subjected to plasma etching to enhance its surface hydrophilicity; finally, the polypeptide-functionalized AIE nanofiber is adsorbed on the surface of four surgical sutures through hydrophilic interaction and electrostatic interaction, and finally a surface-functionalized surgical suture is prepared.

[0012] CN 116427042 A discloses a method and device for producing nanofiber yarn by centrifugal method. The method comprises: in the process of preparing nanofiber by centrifugal spinning, the horizontal outward airflow generated by the rotation of a spinning disk is converted into a spiral airflow field to draw and twist the spinning liquid sprayed from a spinneret to obtain the nanofiber yarn; the device comprises a spinning disk (4), a receiving device, a driving device and a self-twisting device (5); the spinning disk (4) comprises a vertical cylindrical barrel I, a spinning liquid storage cavity is arranged inside the cylindrical barrel I, a spinneret connected to the spinning liquid storage cavity is arranged on the circumference of the cylindrical barrel I, and the liquid outlet direction of the spinneret is horizontal; the self-twisting device (5) comprises a horizontal cylindrical tube I, a horizontal cylindrical tube II, a rolling ball (5-1), a fan blade (5-4), a wind collecting cover and a wind gathering cover (5-2).

[0013] Although the above patented technologies provide a nanofiber surface for sutures, which can promote cell adhesion, proliferation, migration and differentiation, they still use micron fibers as the core structure or adsorption structure. Neither the skin-core design nor the nanofiber adsorption can ensure the stability of the overall structure of the suture. The nanofiber layer is easy to fall off, the nanofibers are arranged in a disorderly manner, and the adsorption amount is random. The method of collecting and twisting the yarn by centrifugal means, although the overall stability of the overall structure is improved compared with the skin-core structure, cannot guarantee the high orientation of the large number of nanofibers that make up the yarn. In other words, the arrangement of the nanofibers is also disorderly, and thus it cannot guarantee that its mechanical properties meet the requirements of surgical sutures. Moreover, the overall process flow of the above technologies is cumbersome and complex, which is not conducive to industrial production. Therefore, how to prepare surgical sutures that meet actual use needs based on nanofiber structures, so that they have bionic characteristics while ensuring structural stability, so that the sutures can promote wound healing and assist in repair and regeneration during use, has become a difficult problem that technicians in the field of absorbable nanofiber surgical sutures need to solve urgently. Summary of the invention

[0014] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a method and device for preparing highly oriented electrostatically spun nanofiber absorbable surgical sutures, which can make the arrangement of nanofibers in yarn highly oriented and orderly, and can greatly improve the mechanical properties and overall structural stability under the condition of the same wire diameter.

[0015] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a highly oriented electrospun nanofiber absorbable surgical suture, comprising the following steps:

[0016] 1. Preparation of spinning solution

[0017] (1) dissolving a certain amount of absorbable polymer in an organic solvent, stirring the mixture under magnetic force and allowing it to stand for a certain period of time to prepare a spinning precursor of a certain concentration for later use;

[0018] 2. Preparation of Oriented Nanofiber Bundles

[0019] (2) spinning the spinning precursor obtained in step (1) through an electrospinning device under certain spinning conditions to adhere and fix the continuously produced nanofibers;

[0020] (3) screening and intercepting the nanofibers with the same or similar arrangement directions among the adhered and fixed nanofibers;

[0021] (4) flattening and accumulating the nanofibers obtained by screening and interception to obtain an oriented nanofiber bundle horizontally spread along the radial direction of the nanofibers;

[0022] 3. Preparation of strips

[0023] (5) cutting the oriented nanofiber bundle obtained in step (4) into strips of a certain width along the arrangement direction of the fibers for later use;

[0024] 4. Preparation of Nanofiber Wires

[0025] (6) Fixing one end of the cut strip and twisting the other end clockwise or counterclockwise to form a nanofiber wire;

[0026] 5. Hot drawing treatment

[0027] (7) thermally stretching the nanofiber wire obtained in step (6), and then naturally cooling it to room temperature;

[0028] (8) Obtain absorbable surgical sutures.

[0029] In the method for preparing the above-mentioned highly oriented electrospun nanofiber absorbable surgical suture, in the step (1), the absorbable polymer is any one of polycaprolactone, polyglycolide, poly-L-lactic acid, gelatin, and collagen, the organic solvent is hexafluoroisopropanol, and the concentration of the spinning precursor is 6%-21%.

[0030] In the above-mentioned method for preparing highly oriented electrospun nanofiber absorbable surgical sutures, in the step (2), the electrospinning voltage is ±12 kV, the spinning precursor extrusion rate is 0.8 mL / h, the collection time is 15 min, the spinning temperature is 20° C., and the relative humidity is 35%.

[0031] In the above method for preparing highly oriented electrospun nanofiber absorbable surgical sutures, in step (5), the nanofiber bundle is cut to a width of 3 cm.

[0032] In the above method for preparing highly oriented electrospun nanofiber absorbable surgical sutures, in step (6), the degree of twisting is 7 turns / cm.

[0033] In the above method for preparing highly oriented electrospun nanofiber absorbable surgical sutures, in step (7), the hot stretching temperature is 60° C., the hot stretching force is 20N, and the fiber is stretched to twice its initial length.

[0034] A preparation device for highly oriented electrospun nanofiber absorbable surgical sutures, comprising a spinning device having a liquid supply box, a high voltage power supply and an electrospinning nozzle, wherein two conductive conveyor belts moving in opposite directions are arranged vertically and relatively parallel below the electrospinning nozzle for adhering and fixing nanofibers formed by jetting fine streams and driving them to move downward, a receiving area for adhering nanofibers with consistent or similar arrangement directions is formed between the two conductive conveyor belts, a whipping area is formed between the electrospinning nozzle and the top of the conductive conveyor belt, a collecting plate for intercepting and flattening the nanofibers adhered and fixed between the two conductive conveyor belts to accumulate and stack to form an oriented nanofiber bundle is arranged at the bottom of the receiving area, and further comprising:

[0035] A cutting mechanism for cutting the formed oriented nanofiber bundle into strips of a certain width along the arrangement direction of the fibers;

[0036] A twisting mechanism for fixing one end of the cut strip and twisting the other end clockwise or counterclockwise to form a nanofiber line;

[0037] A stretching and shaping mechanism for thermally stretching nanofiber wires.

[0038] In the above device, the collecting plate is arranged between the two conductive conveyor belts and is vertically disposed with respect to the two conductive conveyor belts.

[0039] In the above device, the width of the collecting plate is ≥ the width of the conductive conveyor belt, and the length of the collecting plate is ≤ the spacing between the two conductive conveyor belts.

[0040] In the above-mentioned device, the height of the conductive conveyor belt is 30 cm, the width is 10 cm, the distance between the two conductive conveyor belts is 20 cm, the rotation speed of the conductive conveyor belt is 60 cm / min, the length of the collecting plate is 18 cm, the width is 15 cm, and the distance between the electrospinning nozzle and the collecting plate is 45 cm.

[0041] The advantages of the preparation method and device of the highly oriented electrostatically spun nanofiber absorbable surgical suture of the present invention are: a pair of mutually opposed and parallel conductive conveyor belts are used to overlap and collect the nanofibers generated by electrostatic spinning. Due to the width limit of the conductive conveyor belt, only the nanofibers within the fixed tilt angle range can be retained between the two conductive conveyor belts, and the nanofibers with a large tilt angle cannot adhere to the two conductive conveyor belts and are abandoned. At the same time, a collection plate perpendicular to it is set between the conveyor belts. When the conveyor belts run in opposite directions, the nanofiber webs retained between the conveyor belts move with the conveyor belts until they are intercepted by the collection plate. After a period of accumulation, an oriented nanofiber bundle with the same or similar fiber arrangement direction is formed on the collection plate. Subsequently, the two-dimensional nanofiber bundle is twisted into a three-dimensional linear structure with a tight structure according to demand, and the orientation and crystallinity of the nanofibers are further enhanced by a hot stretching process, so as to obtain a nanofiber surgical suture with excellent mechanical properties and biosafety. Therefore, by adopting the electrostatic spinning web laying-twisting molding process and the hot stretching process, an integrated nanofiber surgical suture with a high degree of orientation can be obtained, and the suture structure is complete and stable, the process flow is simple, and the operation and regulation are flexible. The absorbable nanofiber surgical suture produced by the present invention breaks through the limitations of traditional micron fiber surgical sutures, can orient and arrange the nanofibers in the same direction and ensure that the mechanical properties meet the use requirements, further improving the therapeutic effect of surgical sutures. The present invention is composed of integrated nanofibers, and has high orientation, uniform structure, strong mechanical properties, degradability and excellent biosafety, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of the preparation process of the highly oriented electrospun nanofiber absorbable surgical suture of the present invention;

[0043] Figure 2 It is a schematic structural diagram of a device for preparing absorbable surgical sutures of the present invention;

[0044] Figure 3 A schematic structural diagram of a second device for preparing absorbable surgical sutures provided in Example 7;

[0045] Figure 4 A schematic structural diagram of a third device for preparing absorbable surgical sutures provided in Example 8;

[0046] Figure 5 The electron microscope photographs of the nanofiber and absorbable nanofiber suture prepared in Example 1;

[0047] Figure 6 The electron microscope photograph of the nanofiber and absorbable nanofiber suture prepared in Example 2;

[0048] Figure 7The electron microscope photographs of the nanofiber and absorbable nanofiber suture prepared in Example 3;

[0049] Figure 8 The electron microscope photographs of the nanofibers and absorbable nanofiber sutures prepared in Example 4;

[0050] Fig. 9 The electron microscope photographs of the nanofibers and absorbable nanofiber sutures prepared in Example 5;

[0051] Fig.10 This is an electron microscope photograph of the nanofiber and absorbable nanofiber suture prepared in Example 6. DETAILED DESCRIPTION

[0052] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0053] In the present invention, unless otherwise stated, directional words such as "upper" and "lower" generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the attached drawings; while "inside" and "outside" refer to the outline of the device. In addition, in the description of this application, the term "including" means "including but not limited to". The terms first, second, third, etc. are used only as labels and do not impose numerical requirements or establish an order. The term "plurality" means "two or more".

[0054] like Figure 1 As shown, a method for preparing a highly oriented electrospun nanofiber absorbable surgical suture comprises the following steps:

[0055] 1. Preparation of spinning solution

[0056] (1) dissolving a certain amount of absorbable polymer in an organic solvent, stirring the mixture under magnetic force and standing it for a certain period of time to prepare a spinning precursor of a certain concentration for later use; the absorbable polymer is any one of polycaprolactone, polyglycolide, poly-L-lactic acid, gelatin, and collagen, and the organic solvent is hexafluoroisopropanol;

[0057] 2. Preparation of Oriented Nanofiber Bundles

[0058] (2) spinning the spinning precursor obtained in step (1) through an electrospinning device under certain spinning conditions to adhere and fix the continuously produced nanofibers;

[0059] (3) screening and intercepting the nanofibers with the same or similar arrangement directions among the adhered and fixed nanofibers;

[0060] (4) flattening and accumulating the nanofibers obtained by screening and interception to obtain an oriented nanofiber bundle horizontally spread along the radial direction of the nanofibers;

[0061] 3. Preparation of strips

[0062] (5) cutting the oriented nanofiber bundle obtained in step (4) into strips of a certain width along the arrangement direction of the fibers for later use;

[0063] 4. Preparation of Nanofiber Wires

[0064] (6) Fixing one end of the cut strip and twisting the other end clockwise or counterclockwise to form a nanofiber wire;

[0065] 5. Hot drawing treatment

[0066] (7) thermally stretching the nanofiber wire obtained in step (6), and then naturally cooling it to room temperature;

[0067] (8) Obtain absorbable surgical sutures.

[0068] like Figure 2 As shown, a device for preparing highly oriented electrospun nanofiber absorbable surgical sutures includes a spinning device having a liquid supply box 1, a high voltage power supply 2 and an electrospinning nozzle 3. Two conductive conveyor belts 5 for adhering and fixing the nanofibers 4 formed by the jet stream and driving them to move downward are arranged vertically and relatively parallel below the electrospinning nozzle 3. A receiving area 6 for adhering the nanofibers 4 with the same or similar arrangement direction is formed between the two conductive conveyor belts 5. A whipping area 7 is formed between the electrospinning nozzle 3 and the top of the conductive conveyor belt 5. The polymer droplets overcome the surface tension to form the jet stream. During the jetting process of the stream, the solvent evaporates and finally falls on the receiving device, that is, adheres to the conductive conveyor belt 5. The whipping area 7 provides an adjustment effect for the formation and adhesion of the nanofibers 4.

[0069] At the bottom of the receiving area 6, a collecting plate 8 is provided for intercepting the nanofibers 4 adhered and fixed between the two conductive conveyor belts 5 and accumulating and stacking them to form an oriented nanofiber bundle. Specifically, the collecting plate 8 is arranged between the two conductive conveyor belts 5 and is arranged vertically to the two conductive conveyor belts 5. In order to maximize the collection efficiency of the nanofibers 4 and avoid missing the nanofibers 4 adhered to the edges of the two conductive conveyor belts, the width of the collecting plate 8 is ≥ the width of the conductive conveyor belt 5. In order to avoid affecting the normal operation of the two conductive conveyor belts 5 and improve the interception and collection efficiency at the same time, the length of the collecting plate 8 is ≤ the spacing between the two conductive conveyor belts 5. The specific setting of the dimensions of the present invention is as follows: the height of the conductive conveyor belt 5 is 30 cm, the width is 10 cm, the spacing between the two conductive conveyor belts 5 is 20 cm, the rotation speed of the conductive conveyor belt 5 is 60 cm / min, the length of the collecting plate 8 is 18 cm, the width is 15 cm, and the spacing between the electrospinning nozzle 3 and the collecting plate 8 is 45 cm.

[0070] The device also includes: a cutting mechanism for cutting the formed oriented nanofiber bundle into strips of a certain width along the arrangement direction of the fibers; a twisting mechanism for fixing one end of the cut strip and twisting the other end clockwise or counterclockwise to form a nanofiber line; and a stretching and shaping mechanism for thermally stretching the nanofiber line. In the present invention, the twisting mechanism can select a digital yarn twist meter (Y331LN, China); the cutting mechanism can select a film cutting machine (ZX-1625VA, Zhuoxing); the stretching and shaping mechanism can select a hot stretching and shaping machine (TL018-1, Tianli Textile Machinery). Since the above mechanisms can be replaced by commonly used equipment in the existing textile field, and can achieve the functions of each step of the present invention and achieve the desired technical effects, they will not be introduced in detail.

[0071] about Figure 1 The absorbable nanofiber suture shown in the figure shows that the internal nanofibers are parallel to each other. The explanation is as follows: due to the effect of thermal stretching, the length of the nanofiber line increases, while the overall number of twisting turns remains unchanged, resulting in the degree of twisting of each centimeter of fiber decreasing until it is negligible, making the angle between the fiber and the axial direction of the nanofiber line greatly reduced, and presenting a fiber arrangement state that is highly oriented to the axial direction of the nanofiber line in the local area; at the same time, the nanofibers are tightly hugged to form a nanofiber linear structure with a smooth macroscopic surface and no obvious twist. Therefore, when one point of the absorbable nanofiber suture is magnified, although the fibers are parallel to each other, they still have a certain degree of twist. The thermal stretching step not only gives the absorbable nanofiber suture excellent mechanical properties, but also maximizes the high orientation of the nanofibers, which meets the basic performance requirements of the suture.

[0072] The nanofiber surgical suture prepared by the above method of the present invention, due to the selection effect of the conveyor belt on the nanofibers, only the fibers with an inclination angle within a specified range can be retained, and then accumulated and stacked on the collection plate layer by layer to form an oriented nanofiber bundle with a certain thickness. The two-dimensional structure can be transformed into a three-dimensional structure by using the torsion process, laying the foundation for subsequent hot stretching, and the hot stretching process can greatly promote the arrangement and formation of polymer macromolecular crystal regions, improve the fiber crystallinity and orientation, so that the suture as a fiber assembly can obtain more excellent mechanical properties. At the same time, during the hot stretching process, the nanofibers with inconsistent orientations in the suture can be further adjusted to make their orientations consistent. The absorbable polymers described in the present invention include natural absorbable polymers and synthetic absorbable polymers, specifically including spinning solutions composed of poly-L-lactic acid and polyglycolide as polymers in dichloromethane / N,N-dimethylformamide (v / v=3 / 1) as solvents, or spinning solutions composed of chitosan and polyamide as polymers in formic acid solution as solvents, or spinning solutions composed of polyacrylonitrile, polyurethane or polydioxanone as polymers in N,N-dimethylformamide as solvents, or spinning solutions composed of polyvinyl alcohol or gelatin as polymers in water (>80°C) as solvents. The preparation process described in the present invention can be widely applied to various polymers suitable for electrospinning, such as polyacrylonitrile, polyamide, polyurethane, polyvinyl alcohol, polydioxanone, cellulose, etc.

[0073] The present application is described in detail below through specific embodiments. The following embodiments are only partial embodiments of the present application and are not limitations of the present application.

[0074] Example 1

[0075] A method for preparing highly oriented electrostatically spun nanofiber absorbable surgical sutures comprises the following steps:

[0076] 1. Preparation of spinning solution

[0077] (1) dissolving a certain amount of polycaprolactone in hexafluoroisopropanol, and allowing to stand overnight with magnetic stirring to prepare a polycaprolactone spinning precursor with a concentration of 6%, which is then used for later use;

[0078] 2. Preparation of Oriented Nanofiber Bundles

[0079] (2) spinning the spinning precursor prepared in step (1) through an electrospinning device under certain spinning conditions to adhere and fix the continuously produced nanofibers; the spinning conditions are: electrospinning voltage is ±12 kV, spinning precursor extrusion speed is 0.8 mL / h, conductive conveyor belt height is 30 cm, width is 10 cm, spacing between conductive conveyor belts is 20 cm, conductive conveyor belt rotation speed is 60 cm / min, collecting plate length is 18 cm, width is 15 cm, spacing between electrospinning nozzle and collecting plate is 45 cm, collecting time is 15 min, spinning temperature is 20° C., relative humidity is 35%;

[0080] (3) screening and intercepting the nanofibers with the same or similar arrangement directions among the adhered and fixed nanofibers;

[0081] (4) flattening and accumulating the nanofibers obtained by screening and interception to obtain an oriented nanofiber bundle horizontally spread along the radial direction of the nanofibers;

[0082] 3. Preparation of strips

[0083] (5) Cut the oriented nanofiber bundle obtained in step (4) into strips with a width of 3 cm along the fiber arrangement direction for later use;

[0084] 4. Preparation of Nanofiber Wires

[0085] (6) Fix one end of the cut strip and twist the other end clockwise or counterclockwise to form a nanofiber line, with a twisting degree of 7 turns / cm;

[0086] 5. Hot drawing treatment

[0087] (7) thermally stretching the nanofiber wire obtained in step (6) at a temperature of 60° C. and a thermal stretching force of 20 N to twice its initial length, and then naturally cooling to room temperature;

[0088] (8) Obtain absorbable surgical sutures.

[0089] Example 2

[0090] The same parts as those of Example 1 are not described in detail. The difference between the present embodiment and Example 1 is that in step (1), a certain amount of polycaprolactone is dissolved in hexafluoroisopropanol to prepare a spinning solution precursor with a concentration of 9%.

[0091] Example 3

[0092] The same parts as those of Example 1-2 are not described in detail. The difference lies in that: in step (1), a certain amount of polycaprolactone is dissolved in hexafluoroisopropanol to prepare a spinning solution precursor with a concentration of 12%.

[0093] Example 4

[0094] The same parts as those of Examples 1-3 are not described again. The difference lies in that: in step (1), a certain amount of polycaprolactone is dissolved in hexafluoroisopropanol to prepare a spinning solution precursor with a concentration of 15%.

[0095] Example 5

[0096] The same parts as those of Examples 1-4 are not described in detail. The difference lies in that: in step (1), a certain amount of polycaprolactone is dissolved in hexafluoroisopropanol to prepare a spinning solution precursor with a concentration of 18%.

[0097] Example 6

[0098] The same parts as those of Examples 1-5 are not described in detail. The difference lies in that in step (1), a certain amount of polycaprolactone is dissolved in hexafluoroisopropanol to prepare a spinning solution precursor with a concentration of 21%.

[0099] Example 7

[0100] like Figure 3 As shown, this embodiment provides a second device for preparing highly oriented electrospun nanofiber absorbable surgical sutures. Figure 2 The similarities are not repeated here, and the difference lies in that a collecting conveyor belt 9 is provided at the bottom of the receiving area 6 for intercepting the nanofibers adhered and fixed between the two conductive conveyor belts 5 and flattening and accumulating them to form an oriented nanofiber bundle. The collecting conveyor belt 9 can continuously and automatically output the oriented nanofiber bundles formed by intercepting and flattening the accumulated stacking from the receiving area 6, thereby achieving the purpose of automatic output of the oriented nanofiber bundles, reducing the labor intensity of workers, improving the level of automation, and being suitable for industrial applications.

[0101] Example 8

[0102] like Figure 4 As shown, this embodiment provides a third device for preparing highly oriented electrospun nanofiber absorbable surgical sutures. Figure 2 , Figure 3The similarities are not repeated here, but the differences are as follows: a collecting conveyor belt 10 is provided at the bottom of the receiving area 6 for intercepting and paving the nanofibers adhered and fixed between the two conductive conveyor belts 5 to form an oriented nanofiber bundle, and a second conveyor belt 11 is connected to the collecting conveyor belt 10 for outputting the intercepted and paved accumulated nanofiber bundles to form an oriented nanofiber bundle, and realizing continuous overlap of the oriented nanofiber bundles along the fiber length direction. A third conveyor belt 12 associated with a cutting mechanism is provided at the output end of the second conveyor belt for the cutting process. The second conveyor belt 11 is tilted and tilted downward from the receiving area 6 to facilitate the continuous output of the oriented nanofibers along their length direction. During the output process, it can achieve the purpose of automatically overlapping the oriented nanofiber bundles, which makes it possible to prepare continuous absorbable surgical sutures. It has a simple structure and low cost, and is suitable for industrial applications.

[0103] The present invention utilizes an electrospinning laying-twist forming process, and then a hot stretching process to prepare absorbable nanofiber surgical sutures under different process parameters. The test results of the mechanical properties, surface morphology and biocompatibility are as follows:

[0104] 1. Mechanical properties and surface morphology

[0105] Examples 1-6 respectively obtained 6 different concentrations (6% PCL, 9% PCL, 12% PCL, 15% PCL, 18% PCL, 21% PCL) of PCL absorbable nanofiber surgical sutures. The morphology and structure were observed using a scanning electron microscope (TESCAN VEGA3, Czech Republic). In order to improve the conductivity of the combined line, gold was sprayed on the sample surface for 160s. ImageJ software (National Institutes of Health, USA) was used to measure the average wire diameter and average fiber diameter. 100 positions were randomly selected for each sample for measurement and statistics. Its surface morphology Figure 5-10 As shown, the fiber diameter and suture diameter were measured, and the results are shown in Table 1. Analysis shows that the fibers in the obtained surgical sutures are nano-scale fibers, and the nanofibers are uniform in morphology without obvious beads. When the PCL concentration reaches 12%, the fibers are highly oriented along the axial direction of the suture, and the suture structure is uniform and smooth. As the polymer concentration increases, the fiber diameter and wire diameter gradually increase. XRD analysis was performed using a Japanese Rigaku Ultima IV type Cu Kα radiation source with a scanning rate of 8°(2θ) / min and a scanning range of 5°~60°(2θ). The crystallinity of the six PCL nanofiber surgical sutures was measured to be 43.6%, 50.3%, 54.6%, 54.3%, 55.6%, and 57.3%, respectively.

[0106] Table 1 Fiber diameters and wire diameters of six PCL nanofiber surgical sutures

[0107] sample Wire diameter(μm) Fiber diameter (nm) 6% PCL 272.5±1.5 629.3±53.5 9% PCL 379.7±1.5 735.7±25.0 12% PCL 418.1±2.3 828.4±19.4 15% PCL 446.6±5.4 887.3±2.5 18% PCL 510.2±3.5 895.1±1.3 21% PCL 640.0±5.1 902.5±1.6

[0108] The mechanical properties of 6 types of PCL nanofiber surgical sutures were tested according to YY 1116-2020, and the results are shown in Table 2.

[0109] Table 2 Mechanical properties of six PCL nanofiber surgical sutures

[0110] sample Breaking load(N) Breaking strength(MPa) Elongation at break (%) 6% PCL 4.0±0.2 69.3±9.1 152.2±11.0 9% PCL 21.5±0.8 190.0±8.0 257.2±29.5 12% PCL 26.6±0.2 193.4±3.2 292.2±8.6 15% PCL 28.9±8.9 186.2±15.5 269.1±33.4 18% PCL 27.4±4.6 130.1±10.4 315.8±24.1 21% PCL 34.7±0.9 107.8±3.0 276.5±25.2

[0111] 2. Biocompatibility

[0112] The obtained PCL nanofiber surgical sutures were subjected to an in vitro cytotoxicity test with reference to GBT 16886.5-2017, and the measured fibroblast survival rate is shown in Table 3, which proves that all the samples are non-cytotoxic.

[0113] Table 3 Cytocompatibility of six PCL nanofiber surgical sutures

[0114] sample Day 1 Day 3 6% PCL 99.8％ 99.5％ 9% PCL 99.7％ 99.5％ 12% PCL 99.9％ 99.4％ 15% PCL 99.6％ 99.4％ 18% PCL 99.8％ 98.8％ 21% PCL 99.9％ 99.4％

[0115] From the above experimental results, it can be seen that by comparing the fiber diameter, wire diameter, mechanical properties and cytotoxicity of the six PCL nanofiber surgical sutures, it can be concluded that:

[0116] The absorbable nanofiber surgical suture provided by the present invention has a uniform and smooth nanoscale appearance, excellent mechanical properties, and good cell compatibility. As the PCL concentration increases, the fiber diameter and wire diameter increase slightly, the crystallinity increases, and the breaking strength increases significantly. This is because thermal stretching can effectively promote the formation of crystal regions in polymers, increase the crystallinity of sutures, and greatly improve the fiber orientation, which is manifested as an improvement in the mechanical properties of sutures. Taking all factors into consideration, the absorbable nanofiber suture finally obtained by selecting the 12% PCL concentration used in Example 3 of the present invention has the best overall performance.

[0117] By using the electrospinning web laying technology, the disordered nanofibers can be spread and collected in a specific direction. The strip twisting method can be used to easily and efficiently convert the two-dimensional nanofiber bundles into three-dimensional nanofiber wires. The subsequent hot drawing process can further improve the structure and performance of the three-dimensional nanofiber wires, reduce the wire diameter of the nanofiber sutures, improve their crystallinity and orientation, and enhance their mechanical properties. The preparation process of the present invention has a complete and continuous structure of the nanofiber sutures, with the fibers tightly hugging each other, a stable suture structure that is not easy to separate, superior mechanical properties, and good biosafety.

[0118] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Any changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention should fall within the protection scope of the present invention.

Claims

1. A method for preparing highly oriented electrospun nanofiber absorbable surgical sutures, characterized in that: The steps include:

1. Preparation of spinning solution (1) dissolving a certain amount of absorbable polymer in an organic solvent, stirring the mixture under magnetic force and allowing it to stand for a certain period of time to prepare a spinning precursor of a certain concentration for later use; 2. Preparation of Oriented Nanofiber Bundles (2) spinning the spinning precursor obtained in step (1) through an electrospinning device under certain spinning conditions to adhere and fix the continuously produced nanofibers; (3) screening and intercepting the nanofibers with the same or similar arrangement directions among the adhered and fixed nanofibers; (4) flattening and accumulating the nanofibers obtained by screening and interception to obtain an oriented nanofiber bundle horizontally spread along the radial direction of the nanofibers; 3. Preparation of strips (5) cutting the oriented nanofiber bundle obtained in step (4) into strips of a certain width along the arrangement direction of the fibers for later use; 4. Preparation of Nanofiber Wires (6) Fixing one end of the cut strip and twisting the other end clockwise or counterclockwise to form a nanofiber wire; 5. Hot drawing treatment (7) thermally stretching the nanofiber wire obtained in step (6), and then naturally cooling it to room temperature; (8) Obtain absorbable surgical sutures.

2. The method for preparing highly oriented electrospun nanofiber absorbable surgical suture according to claim 1, characterized in that: In the step (1), the absorbable polymer is any one of polycaprolactone, polyglycolide, poly-L-lactic acid, gelatin, and collagen, the organic solvent is hexafluoroisopropanol, and the concentration of the spinning precursor is 6%-21%.

3. The method for preparing highly oriented electrospun nanofiber absorbable surgical suture according to claim 1, characterized in that: In the step (2), the electrospinning voltage is ±12 kV, the spinning precursor extrusion speed is 0.8 mL / h, the collection time is 15 min, the spinning temperature is 20° C., and the relative humidity is 35%.

4. The method for preparing the highly oriented electrospun nanofiber absorbable surgical suture according to claim 1, characterized in that: In the step (5), the nanofiber bundle is cut to a width of 3 cm.

5. The method for preparing highly oriented electrospun nanofiber absorbable surgical suture according to claim 1, characterized in that: In the step (6), the degree of twisting is 7 turns / cm.

6. The method for preparing highly oriented electrospun nanofiber absorbable surgical suture according to claim 1, characterized in that: In the step (7), the hot stretching temperature is 60° C., the hot stretching force is 20 N, and the stretching is performed to twice the initial length.

7. A device for realizing the method for preparing highly oriented electrospun nanofiber absorbable surgical sutures according to any one of claims 1 to 6, comprising a spinning device having a liquid supply box, a high voltage power supply and an electrospinning nozzle, characterized in that: Two conductive conveyor belts are arranged vertically and relatively parallel below the electrospinning spinneret and are used to adhere and fix the nanofibers formed by the jet stream and drive them to move downward. A receiving area for adhering nanofibers with the same or similar arrangement directions is formed between the two conductive conveyor belts. A whipping area is formed between the electrospinning spinneret and the top of the conductive conveyor belt. A collecting plate is arranged at the bottom of the receiving area for intercepting and accumulating the nanofibers adhered and fixed between the two conductive conveyor belts to form an oriented nanofiber bundle. The invention also includes: A cutting mechanism for cutting the formed oriented nanofiber bundle into strips of a certain width along the arrangement direction of the fibers; A twisting mechanism for fixing one end of the cut strip and twisting the other end clockwise or counterclockwise to form a nanofiber line; A stretching and shaping mechanism for thermally stretching nanofiber wires.

8. The device according to claim 7, characterized in that: The collecting plate is arranged between the two conductive conveyor belts and is vertically disposed with respect to the two conductive conveyor belts.

9. The device according to claim 7, characterized in that: The width of the collecting plate is ≥ the width of the conductive conveyor belt, and the length of the collecting plate is ≤ the spacing between the two conductive conveyor belts.

10. The device according to claim 7, characterized in that: The height of the conductive conveyor belt is 30 cm, the width is 10 cm, the distance between the two conductive conveyor belts is 20 cm, the rotation speed of the conductive conveyor belt is 60 cm / min, the length of the collecting plate is 18 cm, the width is 15 cm, and the distance between the electrospinning nozzle and the collecting plate is 45 cm.

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