A barbed surgical suture with radiopaque features and method of making

Abstract

The present application belongs to the field of modern textile technology, and relates to a barbed surgical suture with a radiographic function and a preparation method thereof. The barbed surgical suture is prepared by mixing and melting low-molecular-weight left-handed polylactic acid (L-PLLA) and magnetic iron oxide nanocrystals to form a radiographic-polylactic acid (L-PLLA / CM) melt as a core layer, and the skin layer is composed of high-molecular-weight left-handed polylactic acid (H-PLLA) particles. The melt is spun through a skin-core spinning nozzle, and a poly-lactic acid fiber with a barbed skin-core structure is prepared by using the periodic differential operation of the front and rear rollers of a drafting device. After heat treatment, the surgical suture with a radiographic function and controllable degradation is obtained. The surgical suture prepared by the present application has the characteristics of controllable degradation, radiography and secondary cutting-free suture, and the skin-core structure polylactic acid monofilament has excellent biocompatibility, antibacterial performance and thermal stability.

Description

Technical Field

[0001] The invention belongs to the field of modern textile technology and relates to a barbed surgical suture with an imaging function and a preparation method thereof. Background Art

[0002] Polylactic acid fiber is a biodegradable green fiber made of polylactic acid (PLA). It has excellent physical properties and is a new type of biomaterial with broad application prospects. Polylactic acid fiber has good biocompatibility and biodegradability. It can be gradually decomposed into carbon dioxide and water in the body without causing any harm to the human body. Therefore, polylactic acid fiber has great application potential in the medical field, such as making sutures and repairing tissues.

[0003] Current surgical sutures require surface cutting before use to achieve the desired suturing effect. However, the cutting process can increase bacterial infection, sharp burrs on the surface can easily cause tissue trauma, and mechanical properties can be reduced. Biocompatible and degradable surgical sutures have uncontrolled degradation times, which can leave hidden dangers within the body. Conventional angiography, which delivers contrast particles directly into the body, can easily cause complications, leading to secondary tissue infections. These issues introduce numerous inconveniences and risks to surgical procedures and postoperative recovery. Summary of the Invention

[0004] In view of the shortcomings and deficiencies of the above-mentioned prior art, the object of the present invention is to provide a barbed surgical suture with angiographic function and a preparation method thereof. The barbed surgical suture has naturally formed barbs, which can promote wound healing function, and at the same time has excellent angiographic function and a controllable degradation cycle.

[0005] In a first aspect of the present invention, a method for preparing a barbed surgical suture with angiographic function is provided, the method comprising the following steps:

[0006] S1. The granular low molecular weight L-polylactic acid and magnetic iron oxide nanocrystals are uniformly mixed to obtain a core material;

[0007] S2. The core material and the skin material are each melted into a spinning melt and then melt-extruded through a core-skin spinneret to obtain a spinning melt, wherein the skin material is a granular high molecular weight L-polylactic acid;

[0008] S3. The spinning melt is wound around the front roller in a counterclockwise direction from the upper front of the front roller, then wound around the bottom of the front roller, then wound around the rear roller in a clockwise direction, and then wound around the rear roller in a downward direction from the rear side of the rear roller and wound onto the traction roller;

[0009] S4. Controlling the front roller and the rear roller to rotate for a preset time at intervals to obtain a polylactic acid primary fiber with a barbed core-sheath structure; wherein the front roller rotates counterclockwise at a first speed; and the rear roller rotates clockwise at a second speed, wherein the second speed is greater than the first speed;

[0010] S5. The polylactic acid spun fibers are heat-stretched and then heat-treated to regulate crystallinity to obtain polylactic acid monofilaments;

[0011] S6. sterilize and dry the polylactic acid monofilament, and then cool and dry it to obtain the barbed surgical suture.

[0012] In some embodiments of the present invention, the axis of the rear roller is lower than and parallel to the axis of the front roller, and the highest position line of the rear roller is higher than or equal to the lowest position line of the front roller.

[0013] In some embodiments of the present invention, the particle size of the magnetic iron oxide nanocrystals is 10-60 nm.

[0014] In some embodiments of the present invention, in step S1, the mass ratio of low molecular weight L-polylactic acid (L-PLLA) to magnetic iron oxide nanocrystals is (2-10):1.

[0015] In some embodiments of the present invention, in step S1 of the above preparation method, the mass ratio of L-PLLA to magnetic iron oxide nanocrystals is 9:1.

[0016] In some embodiments of the present invention, in step S1, the uniform mixing is specifically: uniform mixing in a twin-screw granulator, the speed of the twin-screw granulator is 260-600 r / min, and the temperature is 190-210°C.

[0017] In some embodiments of the present invention, the molecular weight of the low molecular weight poly (L-lactic acid) is 50,000-70,000 g / mol, and the molecular weight of the high molecular weight poly (L-lactic acid) is 120,000-180,000 g / mol.

[0018] In some embodiments of the present invention, melting the core layer material and the skin layer material into spinning melts is specifically: melt-extrude the core layer material at 190-210°C, and melt-extrude the skin layer material at 220-240°C.

[0019] In some embodiments of the present invention, the diameter ratio of the sheath to the core layer of the sheath-core spinneret is (2-10):1.

[0020] In some embodiments of the present invention, in step S4, the first speed is 1-3 m / s, and the second speed is 6-12 m / s.

[0021] In some embodiments of the present invention, in step S4, the time interval is 0.3 to 1 second, and the preset time is 2 to 4 times the time interval.

[0022] In some embodiments of the present invention, in step S5, the temperature of the hot stretching is 70-90° C., and the total stretching ratio of the hot stretching is 2 times.

[0023] In some embodiments of the present invention, in step S5, the heat treatment is specifically: treating at a temperature of 110-130° C. for 10-30 minutes.

[0024] In some embodiments of the present invention, in step S5 of the preparation method, the sterilization and drying is specifically: drying at 90-100° C. in a sterilization oven for 20-30 minutes.

[0025] The second aspect of the present invention provides a barbed surgical suture with imaging function prepared by the above-mentioned preparation method.

[0026] In some embodiments of the present invention, the diameter of the barbed surgical suture is 0.3-1 mm.

[0027] In some embodiments of the present invention, the barbed surgical suture has a strength of 253 MPa to 300 MPa, a crystallinity of 60 to 85%, and a complete degradation period of 90 to 170 days.

[0028] The third aspect of the present invention provides a front and rear roller periodic stretching device, which is used to stretch the spinning melt once at a time interval to form a nascent fiber with barbs. The front and rear roller periodic stretching device includes a front roller roller, a rear roller roller, a traction roller and a controller arranged in sequence; the rear roller roller is arranged at a rear and lower position of the front roller roller, the axis of the rear roller roller is lower than the axis of the front roller roller and is parallel to the axis, the first element line of the highest position of the rear roller roller is higher than or equal to the second element line of the lowest position of the front roller roller; the axis of the traction roller is lower than the axis of the rear roller roller and is parallel to the axis.

[0029] The controller is used to control the front roller to rotate at a first speed in a counterclockwise direction at every time interval and the rear roller to rotate at a second speed in the opposite direction for a preset time.

[0030] In some embodiments of the present invention, the controller is further configured to control the surface temperature of the front roller.

[0031] In some embodiments of the present application, the axis of the front roller is horizontal, i.e. the front roller is horizontally arranged.

[0032] In some embodiments of the present application, the front roller has the same radius as the end face of the rear roller.

[0033] In some embodiments of the present application, when the front roller has the same radius as the end face of the rear roller, the distance between the first thread and the second thread in the vertical direction is 0-30 cm.

[0034] In some embodiments of the present application, when the front roller has the same radius as the end face of the rear roller, the distance between the axis of the front roller and the axis of the rear roller in the horizontal direction is 1.5R-3R, R being the radius of the end face of the front roller and the rear roller.

[0035] In a fourth aspect of the present application, a use method of the front-rear roller periodic drafting device is provided, and the use method specifically comprises:

[0036] causing the spinning melt to enter the front roller from the upper front side of the front roller in a counterclockwise direction, then to exit from the bottom of the front roller, and then to enter the rear roller in a clockwise direction, and then to exit from the rear side of the rear roller in a downward direction and to be wound on the traction roller;

[0037] controlling the front roller to rotate in a counterclockwise direction at a first speed for a preset time every other time interval, and controlling the rear roller to rotate in a reverse direction at a second speed at the same time.

[0038] In some embodiments of the present application, the use method further comprises: before causing the spinning melt to enter the front roller from the upper front side of the front roller in a counterclockwise direction, controlling the surface temperature of the front roller to be higher than the normal temperature and lower than the melting point of the surface material of the spinning melt.

[0039] Compared with the prior art, the present application has the following technical effects:

[0040] (1) The preparation method provided by the present application cleverly realizes the pre-drafting of the spinning melt before entering the front roller and the drafting of the spinning melt after entering the front roller by designing the differential speed periodic drafting of the front roller and the rear roller. The pre-drafting before entering the front roller makes the spinning melt become a coarse knot spinning melt with a bamboo joint structure, and the drafting after entering the front roller makes the protruding part of the coarse knot spinning melt deform into a hook shape under the differential speed action of the front roller and the rear roller. This method reduces the step of secondary tangent line of the single yarn, greatly reduces the number of single yarn surface spikes, has fewer production procedures, and is suitable for large-scale production.

[0041] (2) The present invention uses a contrast-enhancing-polylactic acid (L-PLLA / CM) material formed by mixing low molecular weight L-polylactic acid (L-PLLA) and magnetic iron oxide nanocrystals as the core material, and uses high molecular weight L-polylactic acid (H-PLLA) particles as the skin material. After forming a melt, it is spun through a skin-core spinneret. The prepared skin-core structured barbed surgical suture thread not only has the advantages of suturing wounds and promoting wound healing during surgery, but also avoids direct contact between contrast particles and the wound surface during contrast examination, thereby improving safety and stability and avoiding the risk of contrast particle leakage and secondary tissue infection.

[0042] (3) The present invention uses low molecular weight left-rotational polylactic acid (L-PLLA) as the main material of the core layer and high molecular weight left-rotational polylactic acid (H-PLLA) particles as the main material of the skin layer. After the two form a melt, they are spun through the skin-core spinneret. The resulting polylactic acid fiber can utilize the molecular weight difference between the skin layer material and the core layer material to adjust the heat treatment temperature to control the crystallinity of the fiber and thus control the degradation cycle of the material.

[0043] (4) The front and rear roller periodic drawing device provided by the present invention can cleverly control the rotation speed of the front and rear rollers from 0 (no rotation) to a certain speed difference between the two while controlling the surface temperature of the front roller to be slightly higher than the material drawing temperature, thereby achieving periodic drawing of the spinning melt and making the nascent fiber have barbs. The shape of the barbs can be regulated by controlling the speed and speed difference of the front and rear rollers. The structure is simple and suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Schematic diagram of the shape change of the spinning melt in the preparation method of the present invention;

[0045] Figure 2 Schematic diagram of the sheath-core spinneret structure in an embodiment of the present invention;

[0046] Figure 3 Schematic diagram of the structure of the front and rear roller periodic drafting device in an embodiment of the present invention;

[0047] Figure 4 This is a schematic structural diagram of a barbed surgical suture obtained in an embodiment of the present invention;

[0048] Figure 5 This is a schematic diagram of the core layer structure of the barbed surgical suture obtained in an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0050] The specifications and manufacturers of the various raw materials used in the examples of this application are all commercially available unless otherwise specified below:

[0051] Low molecular weight L-polylactic acid (L-PLLA) was purchased from Xiamen Anfangxuan Industrial Co., Ltd.

[0052] High molecular weight poly (L-lactic acid) (H-PLLA) was purchased from Xiamen Anfangxuan Industrial Co., Ltd.

[0053] Magnetic iron oxide nanocrystals (Fe3O4) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0054] Tensile strength test: The present invention uses the American NETZSCH INSTRON 5696 universal material testing machine to measure the tensile properties of surgical sutures. The clamping length is set to 100 mm and the tensile speed is set to 200 mm / min. Each sample is tested 5 times and the average value is taken.

[0055] Crystallinity Testing: The crystallinity of surgical sutures was tested using an X-ray diffractometer (Genesis XM, EDAX, USA). XRD testing conditions were as follows: filter: Ni, radiation source: CuKα radiation, wavelength: 0.1542 nm, scan voltage: 40 kV, scan current: 40 mA, scan time: 7 min, scan speed: 3° / min, diffraction angle (2θ): 5-50° (scan interval: 0.02°).

[0056] Degradation cycle test: A gel permeation chromatograph (Agilent PL-GPC50) was used to measure the molecular weight and molecular weight distribution of surgical sutures. A 0.1 mg / mL chloroform solution was used as the mobile phase at a flow rate of 1.0 mL / min and a column temperature of 40°C. Gel permeation chromatography (GPC) was used to test the fiber molecular weight before and after hydrolysis (hydrolysis environment pH 5, temperature 100°C, and hydrolysis time 14 days), and the complete degradation cycle of the fiber was calculated.

[0057] An embodiment of the first aspect of the present invention provides a method for preparing a barbed surgical suture with angiographic function, the method comprising the following steps:

[0058] S1. Homogeneously mixing the low molecular weight L-polylactic acid particles and the magnetic iron oxide nanocrystals to obtain a core layer material. The particle size of the magnetic iron oxide nanocrystals is preferably 10-60 nm. The mass ratio of the L-PLLA particles to the magnetic iron oxide nanocrystals is preferably (2-10):1, more preferably (8-10):1, and more preferably 9:1. The H-PLLA molecular weight is preferably 120000-180000 g / mol, more preferably 160000 g / mol, and the L-PLLA molecular weight is preferably 50000-70000 g / mol, more preferably 50000 g / mol. The L-PLLA with a low molecular weight has a low melt viscosity, which can efficiently mix the iron oxide nanocrystals, and the H-PLLA with a high molecular weight has a high degree of molecular chain entanglement, which can improve the tensile strength, toughness and tear resistance of the skin layer.

[0059] S2. After melting the core layer material and the skin layer material into a spinning melt, melt extrusion is performed through a core-skin spinneret to obtain a spinning melt, and the skin layer material is a high molecular weight L-polylactic acid in particle form.

[0060] S3. The spinning melt is wound into the front roller from the upper front of the front roller in a counterclockwise direction, then wound out from the bottom of the front roller, then wound into the rear roller in a clockwise direction, and then wound out from the rear side of the rear roller in a downward direction and wound onto the traction roller.

[0061] S4. The front roller and the rear roller are controlled to rotate for a preset time at every time interval to obtain a barb core-skin structure polylactic acid nascent fiber; wherein the rotation direction of the front roller is counterclockwise and the rotation speed is a first speed; the rotation direction of the rear roller is clockwise and the rotation speed is a second speed, and the second speed is greater than the first speed; wherein the first speed is preferably 1-3 m / s, and the second speed is preferably 6-12 m / s. The time interval is preferably set to 0.3-1 s, and the preset time is preferably set to 2-4 times the time interval.

[0062] S5. The polylactic acid nascent fiber is heat drawn, and then the crystallinity is regulated by heat treatment to obtain a polylactic acid monofilament.

[0063] S6. The polylactic acid monofilament is sterilized and dried, and then cooled and dried to obtain the controllable degradation surgical suture.

[0064] Figure 1The figure is a schematic diagram of the shape change of the spinning melt in the preparation method of the present invention. In the initial stage, the spinning melt is wound into the front roller from the upper front of the front roller in a counterclockwise direction, then wound out from the bottom of the front roller, and then wound into the rear roller in a clockwise direction, and then wound out from the rear side of the rear roller in a downward direction and wound onto the traction roller; in the preparatory stage and the completion stage, the front and rear rollers and the traction roller are controlled to start periodic operation. On the one hand, since the front and rear rollers rotate at a certain speed, the spinning melt before entering the front roller is pre-stretched into a coarse knot spinning melt with a bamboo structure. On the other hand, since the rotation speed of the rear roller is higher than that of the front roller, the front roller moves at a low speed to form a stretching force F1, which stretches the fiber to move axially in the direction opposite to the direction of fiber movement, and the rear roller moves at a high speed to form a stretching force F2, which stretches the fiber and moves axially in the same direction as the fiber movement. The stretching force F1 cooperates with the stretching force F1 to deform the protruding part of the coarse knot spinning melt into a hook shape under the differential action of the front and rear rollers. Since F2>F1, the direction of the barb formation is the same as the direction of axial movement, and the lower part of the barb is thinner than the upper part.

[0065] In some embodiments of the present invention, in step S1, the uniform mixing is specifically: uniform mixing in a twin-screw granulator, the speed of the twin-screw granulator is 260~600 r / min, and the temperature is 190~210°C, which can make the materials uniformly mixed and improve the imaging effect.

[0066] In some embodiments of the present invention, in step S2, the core layer material and the skin layer material are melted into spinning melts by melt-extruding the core layer material at 190-210°C and the skin layer material at 220-240°C, thereby forming a well-formed skin-core structure monofilament.

[0067] In some embodiments of the present invention, the Figure 2 The sheath-core spinneret of the structure shown is composed of a core layer 1 and a sheath layer 2. The ratio of the sheath diameter d2 to the core diameter d1 is preferably (2-10):1, preferably 9:1.

[0068] In some embodiments of the present invention, in step S4, the temperature of the hot stretching is 70-90° C., and the total stretching ratio of the hot stretching is 2. Hot stretching makes the fibers more uniform.

[0069] In some embodiments of the present invention, in step S4, the heat treatment is specifically performed at a temperature of 110-130°C for 10-30 minutes. This further improves the crystallinity of the fiber while preventing the melting of the barbs, stabilizes the barb structure, increases fiber strength, and regulates the degradation cycle.

[0070] In some embodiments of the present invention, in step S5 of the preparation method, the sterilization and drying is specifically performed by drying in a sterilization oven at 90-100°C for 20-30 minutes to sterilize the fiber surface for direct use in subsequent surgery.

[0071] An embodiment of the second aspect of the present invention provides a barbed surgical suture with imaging function produced by the above-mentioned production method.

[0072] like Figure 4 、 5 As shown, the barbed surgical suture has a skin-core structure, including a fiber skin layer 8, a fiber core layer 9 and barbs 11 distributed on the surface of the fiber skin layer 8, and contrast particles 10, namely magnetic iron oxide (Fe3O4) nanocrystals, are evenly distributed in the fiber core layer 9.

[0073] The skin material is high molecular weight L-polylactic acid (H-PLLA), and the core material is low molecular weight L-polylactic acid (L-PLLA) and magnetic iron oxide nanocrystals, which are mixed and melted to form a contrast-polylactic acid (L-PLLA / CM) melt as the core layer. The skin layer is composed of melted particles.

[0074] In some embodiments of the present invention, the diameter of the barbed surgical suture is 0.3-1 mm.

[0075] In some embodiments of the present invention, the strength of the controllable degradable surgical suture is 253 MPa to 300 MPa, the crystallinity is 60 to 85%, and the complete degradation period is 90 to 170 days.

[0076] like Figure 3 As shown, an embodiment of the third aspect of the present invention provides a front and rear roller periodic stretching device, which is used to stretch the spinning melt once at a time interval to form a nascent fiber with barbs, and the front and rear roller periodic stretching device includes a front roller roller 3, a rear roller roller 4, a traction roller 7 and a controller; the rear roller roller 4 is arranged at a rear and lower position of the front roller roller 3, the axis of the rear roller roller 4 is lower than the axis of the front roller roller 3 and is parallel to it, the first element line of the highest position of the rear roller roller 4 is higher than the second element line of the lowest position of the front roller roller 3 or is at the same height; the axis of the traction roller 7 is lower than the axis of the rear roller roller 4 and is parallel to it; the controller is used to control the front roller roller 3 to rotate counterclockwise at a first speed at each time interval and the rear roller roller 4 to rotate simultaneously in the opposite direction at a second speed.

[0077] In some embodiments of the present invention, the controller is further configured to control the heater to heat the front roller 3 so that the surface temperature of the front roller 3 is higher than room temperature and lower than the melting point of the surface material of the spinning melt.

[0078] In some embodiments of the present invention, the surface of the front roller 3 is provided with a spiral groove with a depth of 0.05-0.2 mm and a groove pitch of 5-10 mm. The spiral groove on the surface of the front roller 3 is used for guiding the wire.

[0079] In some embodiments of the present invention, the rear roller 4 is sprayed with a ceramic coating having a thickness of 0.1 to 0.3 mm, and the coating surface roughness Ra is preferably 1.6 to 3.2 μm. If the surface roughness of the rear roller 4 is too low, the barbs are unevenly distributed. If the surface roughness is too high, the barbs are severely worn.

[0080] In some embodiments of the present invention, a vertical distance between the first element line and the second element line is 0-30 mm.

[0081] In some embodiments of the present invention, when the radii of the end surfaces of the front roller and the rear roller are the same, the projection distance between the first axis and the second axis in the horizontal direction is 1.5R~3R, where R is the radius of the end surfaces of the front roller and the rear roller.

[0082] In some embodiments of the present invention, the first speed is 1-3 m / s, and the second speed is 6-12 m / s.

[0083] A fourth aspect of the present invention provides a method for using the front and rear roller periodic drafting device, wherein the method is as follows:

[0084] S100. The spinning melt is wound counterclockwise from the upper front of the front roller into the front roller 3, then wound out from the bottom of the front roller 3, then wound into the rear roller 4 in a clockwise direction, then wound out from the rear side of the rear roller 4 in a downward direction and wound onto the traction roller 7;

[0085] S200. Control the surface temperature of the front roller to 110~130℃;

[0086] S300. Control the front roller 3 to rotate counterclockwise at a first speed for a preset time at every time interval and control the rear roller 4 to rotate in the opposite direction at a second speed at the same time.

[0087] During the process of the front and rear roller periodic drafting device, the spinning melt in the process before the front roller roller appears as a coarse knot spinning melt 5 with a bamboo structure, and leaves the rear roller roller 4 and enters the traction roller 7 to obtain a fiber 6 with barbs.

[0088] In some embodiments of the present invention, step S100 is specifically as follows: the spinning melt is introduced into the spiral groove of the front roller roller 3 from the upper front of the front roller roller 3 in a counterclockwise direction, then wound out from the bottom of the front roller roller 3, and then wound into the rear roller roller 4 in a clockwise direction under the action of a tension of 5~20 cN, and then wound out from the rear side of the rear roller roller 4 in a downward direction.

[0089] In some embodiments of the present invention, the time interval is 0.3 to 1 second, and the preset time is 2 to 4 times the time interval.

[0090] The front and rear roller periodic drafting device provided by the present invention can adjust the drafting multiple and the barb shape by adjusting the first speed and the second speed.

[0091] The above technical implementation scheme will be illustrated by the following examples.

[0092] Example 1

[0093] (1) Weigh 18g of L-PLLA particles with a molecular weight of 53,000g / mol and 2g of magnetic iron oxide (Fe3O4) nanocrystals and mix them evenly as the core material; weigh 90g of H-PLLA particles with a molecular weight of 160,000g / mol as the skin material. The core material is melted in a twin-screw extruder at a speed of 350m / min and a temperature of 190℃ for 2min. The skin and core materials are melt extruded at a temperature of 220℃.

[0094] (2) The sheath-core melt obtained in step (1) is melt-extruded through a sheath-core spinneret with a diameter ratio of 9:1 to form a spinning melt.

[0095] (3) The spinning melt obtained in step (2) is periodically stretched by front and rear double rollers. Specifically, the surface of the front roller is provided with a spiral groove with a depth of 0.05 mm and a groove pitch of 5 mm. The diameters of the front and rear rollers are both 50 mm. The vertical distance between the first element line and the second element line is 10 mm. The surface of the rear roller is sprayed with a ceramic coating with a thickness of 0.1 mm and a surface roughness Ra of 1.6 μm. The horizontal projection distance between the axes of the front and rear rollers is 75 mm. The front roller is heated to 110° C. and rotated counterclockwise at a low speed of 3 m / s, while the rear roller rotates clockwise at a high speed of 12 m / s. The front and rear rollers are operated for 1 second at a time interval of 0.3 seconds to obtain polylactic acid primary fibers with a barbed skin-core structure.

[0096] (4) The polylactic acid spun fibers obtained in step (3) were subjected to heat drawing at 70° C., with a total drawing ratio of 2, and then heat treated at 110° C. for 20 min to obtain polylactic acid monofilaments.

[0097] (5) The polylactic acid monofilament obtained in step (4) was placed in a high-temperature sterilization box at 90°C and dried for 20 minutes.

[0098] (6) The polylactic acid monofilament obtained in step (5) was cooled and dried to room temperature to obtain a barbed surgical suture with angiographic function. Under the condition of a draft ratio of 2, the barbed surgical suture had a diameter of 0.8 mm. The tensile strength of the suture was 253 MPa and the elongation at break was 35% using an Instron universal tensile tester. The barb length was 0.1 mm and the spacing was 0.5 mm using a Korean COXEM EM-30 electron microscope. The crystallinity of the suture was 60% using an X-ray diffractometer (XRD). The fiber molecular weight before and after hydrolysis (hydrolysis environment pH 5, temperature 100°C, hydrolysis time 14 days) was tested using gel permeation chromatography (GPC), and the degradation completion period of the suture was 90 days.

[0099] Example 2

[0100] (1) Weigh 18g of L-PLLA particles with a molecular weight of 70,000 g / mol and 2g of magnetic iron oxide (Fe3O4) nanocrystals and mix them evenly as the core material; weigh 90g of H-PLLA particles with a molecular weight of 180,000 g / mol as the skin material. The core material is melted in a twin-screw extruder at a speed of 350 m / min and a temperature of 190°C for 2 minutes. The skin and core materials are melt-extruded at a temperature of 220°C.

[0101] (2) The sheath-core melt obtained in step (1) is melt-extruded through a sheath-core spinneret with a diameter ratio of 9:1 to form a spinning melt.

[0102] (3) The spinning melt obtained in step (2) is periodically drawn by a front and rear double roller. Specifically, the surface of the front roller is provided with a spiral groove with a depth of 0.05 mm and a groove pitch of 5 mm. The diameters of the front and rear rollers are both 50 mm. The vertical distance between the first element line and the second element line is 10 mm. The surface of the rear roller is sprayed with a ceramic coating with a thickness of 0.1 mm and a surface roughness Ra of 1.6 μm. The projection distance between the axes of the front and rear rollers in the horizontal direction is 150 mm. The front roller is heated to 120° C. and rotated counterclockwise at a low speed of 3 m / s, while the rear roller rotated clockwise at a high speed of 12 m / s. The front and rear rollers are operated for 1 second at a time interval of 0.5 seconds to obtain polylactic acid primary fibers with a barbed core-skin structure.

[0103] (4) The polylactic acid spun fibers obtained in step (3) were subjected to heat drawing at 70° C., with a total drawing ratio of 2, and then heat-set at 120° C. for 20 min to obtain polylactic acid monofilaments.

[0104] (5) The polylactic acid monofilament obtained in step (4) was placed in a high-temperature sterilization box at 90°C and dried for 20 minutes.

[0105] (6) The surgical suture obtained in step (5) was cooled and dried to room temperature to obtain a barbed surgical suture. Under the condition of a drafting multiple of 2, the diameter of the obtained polylactic acid monofilament was 0.8 mm. After heat treatment to improve the mechanical properties of the fiber, the tensile strength of the suture was 296 MPa and the elongation at break was 31% using an Instron universal tensile tester. The barb length was 0.1 mm and the spacing was 0.4 mm using a Korean COXEM EM-30 electron microscope. The crystallinity of the suture was 71% using an X-ray diffractometer (XRD). The fiber molecular weight before and after hydrolysis (hydrolysis environment pH 5, temperature 100°C, hydrolysis time 14 days) was tested using gel permeation chromatography (GPC), and the degradation completion period of the suture was 107 days.

[0106] Example 3

[0107] (1) Weigh 18 g of L-PLLA particles with a molecular weight of 53,000 g / mol and 2 g of magnetic iron oxide (Fe3O4) nanocrystals and mix them evenly as the core material; weigh 90 g of H-PLLA particles with a molecular weight of 160,000 g / mol as the skin material. The core material was melted in a twin-screw extruder at a speed of 350 m / min and a temperature of 190°C for 2 minutes. The skin and core materials were melt extruded at a temperature of 220°C.

[0108] (2) The sheath-core melt obtained in step (1) is melt-extruded through a sheath-core spinneret with a diameter ratio of 9:1 to form a spinning melt.

[0109] (3) The spinning melt obtained in step (2) is periodically drawn by a front and rear double roller. Specifically, the surface of the front roller is provided with a spiral groove with a depth of 0.1 mm and a groove pitch of 10 mm. The diameters of the front and rear rollers are both 60 mm. The vertical distance between the first element line and the second element line is 10 mm. The surface of the rear roller is sprayed with a ceramic coating with a thickness of 0.2 mm and a surface roughness Ra of 2 μm. The projection distance between the axes of the front and rear rollers in the horizontal direction is 90 mm. The front roller is heated to 130° C. and rotated counterclockwise at a low speed of 3 m / s, while the rear roller rotated clockwise at a high speed of 12 m / s. The front and rear rollers are operated for 1 second at a time interval of 0.3 seconds to obtain polylactic acid primary fibers with a barbed skin-core structure.

[0110] (4) The polylactic acid spun fibers obtained in step (3) were subjected to heat drawing at 70° C., with a total drawing ratio of 2 times, and then heat-set at a temperature of 130° C. for 20 minutes to obtain polylactic acid monofilaments.

[0111] (5) The polylactic acid monofilament obtained in step (4) was placed in a high-temperature sterilization box at 90°C and dried for 20 minutes.

[0112] (6) The surgical suture obtained in step (5) was cooled and dried to room temperature to obtain a barbed surgical suture. Under the condition of a draft ratio of 2, the diameter of the obtained polylactic acid monofilament was 0.8 mm. Under low draft ratio stretching, the barb length was short, measured by a Korean COXEM EM-30 electron microscope to be 0.1 mm, and the spacing was 0.4 mm. The tensile strength of the suture was 300 MPa and the elongation at break was 29% using an Instron universal tensile tester. The crystallinity of the suture was 85% using an X-ray diffractometer (XRD). The fiber molecular weight before and after hydrolysis (hydrolysis environment pH 5, temperature 100°C, hydrolysis time 14 days) was tested using gel permeation chromatography (GPC), and the degradation completion period of the suture was 170 days.

[0113] Example 4

[0114] (1) Weigh 18g of L-PLLA particles with a molecular weight of 53,000 g / mol and 2g of magnetic iron oxide (Fe3O4) nanocrystals and mix them evenly as the core material. Weigh 90g of H-PLLA particles with a molecular weight of 160,000 g / mol as the skin material. The core material is melted in a twin-screw extruder at a speed of 350 m / min and a temperature of 190°C for 2 minutes. The skin and core materials are melt-extruded at a temperature of 220°C.

[0115] (2) The sheath-core melt obtained in step (1) is melt-extruded through a sheath-core spinneret with a diameter ratio of 9:1 to form a spinning melt.

[0116] (3) The spinning melt obtained in step (2) is subjected to periodic drafting by front and rear roller pairs, specifically, the surface of the front roller pair is provided with helical grooves with a depth of 0.2 mm and a pitch of 10 mm, the diameters of the front and rear roller pairs are both 60 mm; the distance between the first and second elementary threads in the vertical direction is 20 mm, the surface of the rear roller pair is sprayed with a ceramic coating with a thickness of 0.3 mm, the surface roughness Ra of the coating is 3.2 μm, and the projection distance between the axes of the front and rear roller pairs in the horizontal direction is 180 mm. The front roller pair is heated to 110°C and rotated counterclockwise at a low speed of 3 m / s, and the rear roller pair is rotated clockwise at a high speed of 12 m / s. The front and rear roller pairs are operated for 1.5 s every 0.5 s, and a polylactic acid nascent fiber with a barb skin-core structure is obtained.

[0117] (4) The polylactic acid nascent fiber obtained in step (3) is subjected to heat drafting at 70°C, and the total drafting multiple is 2. Then the fiber is heat set at 110°C for 20 min to obtain a polylactic acid monofilament.

[0118] (5) The polylactic acid monofilament obtained in step (4) is placed in a high-temperature sterilization box at 90°C for drying for 20 min.

[0119] (6) The surgical suture obtained in step (5) is cooled and dried to room temperature to obtain a barb surgical suture. Under the condition of a drafting multiple of 4, the fiber is relatively thin, and the diameter of the obtained polylactic acid monofilament is 0.5 mm. Due to the increase in the drafting multiple, the length and interval of the barbs are increased, and the length is 0.2 mm and the interval is 3 mm as measured by a Korean COXEM EM-30 type electron microscope. The heat treatment temperature is selected to be 110°C, which can maintain the fiber free of defects and obtain good mechanical properties. The tensile strength of the suture is 286 MPa, and the elongation at break is 35% as measured by an Instron universal strength machine. The crystallinity of the suture is 75% as measured by an X-ray diffractometer (XRD). The degradation cycle of the suture is 115 days as measured by gel permeation chromatography (GPC) before and after hydrolysis (hydrolysis environment pH 5, temperature 100°C, hydrolysis time 14 days).

[0120] Example 5

[0121] (1) 18 g of L-PLLA particles with a molecular weight of 53000 g / mol and 2 g of magnetic iron oxide (Fe3O4) nanocrystals were weighed and uniformly mixed as core layer materials; 90 g of H-PLLA particles with a molecular weight of 160000 g / mol were weighed as skin layer materials. The core layer materials were formed into a melt in a twin-screw extruder at a speed of 350 m / min and a temperature of 190°C for 2 min of self-stirring time, and the core-skin materials were melt-extruded at a temperature of 220°C.

[0122] (2) The skin, core melt obtained in step (1) is formed into a spinning melt through a skin-core spinneret with a diameter ratio of 7:3.

[0123] (3) The spinning melt obtained in step (2) is subjected to periodic drafting by front and rear rollers, specifically, the surface of the front roller is provided with a spiral groove with a depth of 0.2 mm and a pitch of 10 mm, and the diameters of the front and rear rollers are both 70 mm; the distance between the first and second elementary threads in the vertical direction is 20 mm, the surface of the rear roller is sprayed with a ceramic coating with a thickness of 0.3 mm, the surface roughness Ra of the coating is 1.6 μm, and the projection distance between the axes of the front and rear rollers in the horizontal direction is 105 mm. The front roller is heated to 110°C and rotated counterclockwise at a low speed of 3 m / s, and the rear roller is rotated clockwise at a high speed of 12 m / s. The front and rear rollers are operated for 2 s at an interval of 0.5 s, and a polylactic acid nascent fiber with a barb skin-core structure is obtained.

[0124] (4) The polylactic acid nascent fiber obtained in step (3) is subjected to heat drawing at 70°C, and the total drawing multiple is 2 times, and then heat setting is performed at a temperature of 110°C for 20 min to obtain a polylactic acid monofilament.

[0125] (5) The polylactic acid monofilament obtained in step (4) is placed in a high-temperature sterilization box at 90°C for drying for 20 min.

[0126] (6) The surgical suture obtained in step (5) is cooled and dried to room temperature to obtain a barb surgical suture. Under the condition of a drawing multiple of 4, the fiber is relatively thin, the diameter of the obtained polylactic acid monofilament is 0.5 mm, the interval between the barbs is relatively large due to the large time interval, and the interval is 5 mm and the length of the barb is 0.2 mm as measured by a Korean COXEM EM-30 type electron microscope; the crystallinity of the fiber is improved due to the large heat contact surface area, and the tensile strength of the suture is 296 MPa and the elongation at break is 32% as measured by an Instron universal testing machine; the crystallinity of the suture is 79% as measured by an X-ray diffractometer (XRD); and the degradation completion period of the suture is 140 days as measured by gel permeation chromatography (GPC) before and after hydrolysis (hydrolysis environment pH 5, temperature 100°C, hydrolysis time 14 days).

[0127] Comparative Example 1

[0128] The core layer material in Example 1 is replaced with: 18 g of H-PLLA particles with a molecular weight of 160000 and 2 g of magnetic iron oxide (Fe3O4) nanocrystals, which are uniformly mixed as the core layer material.

[0129] The obtained barbed surgical suture has a diameter of 0.8 mm. The tensile strength of the suture is 320 MPa as determined by an Instron universal tensile tester. The crystallinity of the suture is 87% as determined by an X-ray diffractometer (XRD). The fiber molecular weight before and after hydrolysis (hydrolysis environment pH 5, temperature 100°C, hydrolysis time 14 days) is tested by gel permeation chromatography (GPC), and the degradation completion period of the suture is 200-300 days.

[0130] According to Comparative Example 1, when both the sheath and the core are made of H-PLLA particles, the degradation period is long.

[0131] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a barbed surgical suture with angiographic function, characterized in that: The preparation method comprises the following steps: S1. The granular low molecular weight L-polylactic acid and magnetic iron oxide nanocrystals are uniformly mixed to obtain a core material; S2. The core material and the skin material are each melted into a spinning melt and then melt-extruded through a core-skin spinneret to obtain a spinning melt, wherein the skin material is a granular high molecular weight L-polylactic acid; S3. The spinning melt is wound around the front roller in a counterclockwise direction from the upper front of the front roller, then wound around the bottom of the front roller, then wound around the rear roller in a clockwise direction, and then wound around the rear roller in a downward direction from the rear side of the rear roller and wound onto the traction roller; S4. Controlling the front roller and the rear roller to rotate for a preset time at intervals to obtain a polylactic acid primary fiber with a barbed core-sheath structure; wherein the front roller rotates counterclockwise at a first speed; and the rear roller rotates clockwise at a second speed, wherein the second speed is greater than the first speed; The first speed is 1-3 m / s, the second speed is 6-12 m / s, the time interval is 0.3-1 s, and the preset time is 2-4 times the time interval; S5. The polylactic acid spun fibers are heat-stretched and then heat-treated to regulate crystallinity to obtain polylactic acid monofilaments; S6. sterilize and dry the polylactic acid monofilament, and then cool and dry it to obtain the barbed surgical suture.

2. The preparation method according to claim 1, characterized in that In step S1, the mass ratio of low molecular weight L-polylactic acid to magnetic iron oxide nanocrystals is (2-10):

1.

3. The preparation method according to claim 1, characterized in that In step S1, the uniform mixing is specifically: uniform mixing in a twin-screw granulator, the speed of the twin-screw granulator is 260-600 r / min, and the temperature is 190-210°C.

4. The preparation method according to claim 1, characterized in that The molecular weight of low molecular weight poly (L-lactic acid) is 50,000-70,000 g / mol, and the molecular weight of high molecular weight poly (L-lactic acid) is 120,000-180,000 g / mol.

5. The preparation method according to claim 1, characterized in that The step of melting the core layer material and the skin layer material into spinning melts is as follows: the core layer material is melt-extruded at 190-210°C, and the skin layer material is melt-extruded at 220-240°C.

6. The preparation method according to claim 1, characterized in that In step S5, the temperature of the hot stretching is 70-90° C., and the total stretching ratio of the hot stretching is 2 times.

7. The preparation method according to claim 1, characterized in that In step S5, the heat treatment is specifically: treating at a temperature of 110-130° C. for 10-30 minutes.

8. A barbed surgical suture with imaging function prepared by the preparation method according to any one of claims 1 to 7.

Images