A method for preparing surgical suture

Abstract

The present invention relates to the technical field of new biomedical materials, and specifically discloses a method for preparing a medical surgical suture, the steps of which are as follows: S1: melt-blending the raw materials for preparing the surgical suture and then performing heat stretching to obtain primary fiber filaments; S2: cold-stretching the unshaped primary fiber filaments along the fiber orientation direction so that the diameter of the primary fiber filaments after cold stretching meets the diameter specification of the surgical suture, and then removing the tensile load to obtain filaments; S3: fixing the two ends of the filaments with a clamp, and then performing thermoplastic shaping treatment on the filaments under the protection of a supercritical fluid to obtain a single-strand surgical suture. The surgical suture prepared by the present invention has good mechanical properties, tissue compatibility and biodegradability, can meet consumers' requirements for degradable sutures, and has broad market prospects.

Description

Technical Field

[0001] The invention relates to the technical field of new biomedical materials, and in particular to a method for preparing a surgical suture. Background Art

[0002] Medical surgical sutures are essential medical materials for suturing wounds after surgery. Surgical sutures usually include soluble and insoluble types. Non-biodegradable sutures cannot be absorbed by the body and have varying degrees of tissue reaction. Suturing the epidermis, especially the local skin, will leave scars. However, biodegradable sutures are easily absorbed or excreted after being degraded in the body tissue, avoiding the pain caused by secondary surgery to the patient, reducing the chance of wound infection, and leaving small scars. Therefore, biodegradable medical sutures are attracting more and more attention.

[0003] The price of hot wire drawing equipment is relatively high, the processing process is relatively complicated, and it requires experienced technicians to operate the equipment, resulting in relatively high costs; the corresponding production process can often only produce sutures of one diameter. Changing the process to produce sutures of different diameters is not suitable for this type of production equipment. The diameter of the sutures used in surgery ranges from thick to thin, and the sizes are varied. Being able to use a simple device to produce sutures of different diameters is the direction of modern production technology innovation. Summary of the invention

[0004] In view of the problems and shortcomings in the prior art, the present invention aims to provide a method for preparing a surgical suture.

[0005] To achieve the purpose of the invention, the technical solution adopted by the present invention is as follows:

[0006] A first aspect of the present invention provides a method for preparing a single-strand surgical suture, comprising the following steps:

[0007] S1: melt-blending raw materials for preparing surgical sutures and then heat-stretching them to obtain primary fiber filaments;

[0008] S2: cold-stretching the primary fiber filaments along the fiber orientation direction according to the diameter specification of the prepared surgical suture, so that the diameter of the primary fiber filaments after cold-stretching meets the diameter specification of the surgical suture, and then removing the tensile load to obtain filaments;

[0009] S3: Fixing the two ends of the filament with a clamp, and then performing thermoplastic shaping treatment on the filament under the protection of a supercritical fluid to obtain a single-strand surgical suture.

[0010] According to the above preparation method, preferably, in step S3, the thermoplastic setting temperature is 25-45° C. and the time is 24 hours.

[0011] According to the above preparation method, preferably, in step S3, the supercritical fluid is carbon dioxide and / or nitrogen; the pressure of the supercritical fluid is 10-17 MPa. More preferably, the supercritical fluid is carbon dioxide.

[0012] According to the above preparation method, preferably, in step S1, the temperature of melt blending is 70-200°C; and the temperature of heat stretching is 70-200°C.

[0013] According to the above preparation method, preferably, in step S2, the temperature of the cold stretching treatment is 15-25° C. More preferably, the temperature of the cold stretching treatment is 25° C.

[0014] According to the above preparation method, preferably, in step S2, the stretching ratio of the cold stretching treatment is 1.2 to 3, and the stretching rate is 1 to 5 mm / min. More preferably, the stretching rate is 1 mm / min.

[0015] According to the above preparation method, preferably, the raw material includes a polymer matrix, and the polymer matrix is ​​PCL (polycaprolactone), polylactic acid or PLCL (poly-L-lactide-caprolactone).

[0016] According to the above preparation method, preferably, the raw material further comprises a fiber-forming phase substance, and the fiber-forming phase substance accounts for 5% to 40% of the total weight of the polymer matrix. More preferably, the fiber-forming phase substance accounts for 20% to 30% of the total weight of the polymer matrix.

[0017] According to the above preparation method, preferably, the raw material further comprises a processing aid, and the processing aid accounts for 1-10% of the total weight of the polymer matrix. More preferably, the processing aid accounts for 3-5% of the total weight of the polymer matrix.

[0018] According to the above preparation method, preferably, the fiber-forming phase material is polylactic acid; and the processing aid is PLCL.

[0019] According to the above preparation method, preferably, the raw material consists of a polymer matrix and a fiber-forming phase material, the polymer matrix is ​​PLCL, and the fiber-forming phase material is polylactic acid; the polylactic acid accounts for 40% of the total weight of PLCL.

[0020] According to the above preparation method, preferably, the raw material consists of a polymer matrix and a fiber-forming phase material, the polymer matrix is ​​PCL, and the fiber-forming phase material is polylactic acid; the polylactic acid accounts for 20% of the total weight of PCL.

[0021] According to the above preparation method, preferably, the raw material consists of a polymer matrix, a fiber-forming phase material and a processing aid; more preferably, the polymer matrix is ​​PCL, the fiber-forming phase material is polylactic acid, and the processing aid is PLCL; the polylactic acid accounts for 20% of the total weight of PCL, and the PLCL accounts for 5% of the total weight of PCL.

[0022] According to the above preparation method, preferably, in step S3, the distance between the two clamps is 1.01 to 1.2 times the original length of the filament in that direction. More preferably, the distance between the two clamps is 1.1 times the original length of the filament in that direction.

[0023] According to the above preparation method, preferably, in step S1, a twin-screw extruder is used for melt blending, and the screw speed of the twin-screw extruder is 90-110 rpm.

[0024] According to the above preparation method, preferably, in step S1, the heat stretching is performed by using a high-speed roller, and the angular velocity of the high-speed roller is 90-110 rad / min.

[0025] A second aspect of the present invention provides a surgical suture prepared using the preparation method described in the first aspect.

[0026] Compared with the prior art, the present invention has the following positive and beneficial effects:

[0027] (1) The polymer raw material of the present invention is prepared by melt blending, extrusion and hot stretching to obtain primary fiber filaments, and then the primary fiber filaments are subjected to 1.2-3 times cold drawing at room temperature. The cold drawing can not only improve the orientation of macromolecules in the suture, but also further improve the crystal structure, induce the oriented crystallization of macromolecules, and improve the mechanical properties of the suture; therefore, after two stretching treatments, a drawn filament with mechanical properties (ultimate tensile stress, elongation at break, elastic modulus) that is better than that of existing commercially available single-strand medical surgical sutures can be obtained.

[0028] (2) The present invention performs thermoplastic shaping on the cold-drawn filaments under the protection of supercritical carbon dioxide fluid, and the supercritical CO 2 The introduction of can reduce the degree of hydrogen bonding of macromolecular materials in the filaments, induce the crystallization of macromolecular materials, further improve the crystallinity of macromolecular materials, and enhance the tensile strength of the suture; moreover, thermoplastic setting can make the polymer molecules transform from an unbalanced conformation to a balanced conformation, thereby eliminating internal stress and improving the dimensional stability of the suture.

[0029] (3) The surgical suture prepared by the present invention preferably uses a polymer matrix, a fiber-forming phase material and a processing aid as raw materials. During the melt extrusion and hot stretching process, the fiber-forming phase material is stretched in situ to form nanofibers with a relatively large aspect ratio inside the polymer primary fiber filaments, thereby increasing the orientation degree of the primary fiber filaments. The increase in the orientation degree causes the macromolecules to be arranged regularly along the axial direction, and the intermolecular force is strong, so the strength is also increased accordingly. The processing aid can play a volume-increasing role, improve the interface between the polymer matrix and the fiber-forming phase material, and further improve the mechanical strength of the surgical suture.

[0030] More preferably, the present invention utilizes the complementary advantages of composite materials, uses PCL (polycaprolactone) as a polymer matrix, and adds polylactic acid (PLA), a fiber-forming phase material, to PCL (polycaprolactone) to improve the crystallinity and mechanical properties of PCL materials; moreover, the present invention uses PLCL as a processing aid, and PLCL, as a copolymer of PCL and PLA, can play a good volume expansion effect, improve the interface between PCL and PLA, and further improve the mechanical strength. Therefore, the present invention forms a complementary advantage effect by blending three materials of PCL, PLA, and PLCL, which not only plays the good plasticity and flexibility of PCL, but also plays the advantage of high strength of PLA. The prepared surgical suture has good mechanical properties, tissue compatibility and biodegradability, which can meet the requirements of consumers for degradable sutures and has broad market prospects.

[0031] (4) The surgical suture preparation method of the present invention can prepare surgical suture products with different diameters and lengths by adjusting the stretching ratios of hot stretching and cold stretching, thereby meeting the demand for sutures with different wire diameters; moreover, the processing equipment of the medical surgical suture of the present invention is simple, economical, and the process is simple and flexible. Sutures of different diameters can be produced on the same machine without changing the preparation process; and the production energy consumption is low.

[0032] (5) The degradable suture produced by the present invention belongs to biomedical textiles, which is a frontier field in the textile field and has the characteristics of high-tech content and high added value. It is of great significance to promote the industrial upgrading of the local traditional textile industry and the creation of income for enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the process of preparing a single-strand surgical suture of the present invention;

[0034] Figure 2 This is a diagram showing the diameter detection result of the surgical suture prepared in Example 1 of the present invention;

[0035] Figure 3 This is a diagram of the crystallization state of the single-strand surgical suture of the present invention during the supercritical fluid thermoplastic shaping process. DETAILED DESCRIPTION

[0036] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0037] The experimental methods in the following examples without specifying specific conditions all adopt conventional techniques in the art or follow the conditions recommended by the manufacturers; the reagents or instruments used without specifying the manufacturers are all conventional products that can be obtained commercially.

[0038] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the present invention is further described in detail through specific embodiments, but the scope of the present invention is not limited thereto.

[0039] Embodiment 1:

[0040] A method for processing a single-strand surgical suture (eg Figure 1 As shown), comprising the following steps:

[0041] S1: Dry the raw materials for preparing surgical sutures and mix them evenly, and melt blend them through a twin-screw extruder; the temperature settings of the twin-screw extruder from the barrel to the die are 170°C, 190°C, 190°C and 180°C, respectively, and the speed of the twin-screw extruder is 80rpm. After the blend exits the die of the twin-screw extruder, a high-speed roller is used for heat stretching to obtain primary fiber filaments, which are cooled in a water bath and then wound and collected on a roller. During the heat stretching, the speed of the high-speed roller is 90rad / min; the temperature of the heat stretching is 180°C.

[0042] The raw material consists of a polymer matrix, a fiber-forming phase material and a processing aid, wherein the polymer matrix is ​​PCL, the fiber-forming phase material is PLA, and the processing aid is PLCL; PLA accounts for 20% of the total weight of PCL, and PLCL accounts for 5% of the total weight of PCL.

[0043] S2: According to the diameter specification of the prepared surgical suture, at room temperature, the primary fiber filaments are cold stretched using a universal stretching machine along the fiber orientation direction, so that the diameter of the primary fiber filaments after cold stretching meets the diameter specification standard of surgical suture 7-0, and then the tensile load is removed to obtain filaments. The stretching ratio of the cold stretching treatment is 1.2-3, and the stretching rate is 1 mm / min.

[0044] S3: Fix the two ends of the filament with a clamp (the distance between the two clamps is 1.1 times the original length of the filament in that direction), and then 2The filaments are subjected to thermoplastic shaping treatment under protection to obtain a single-strand surgical suture (the specification of the surgical suture is 7-0). 2 The pressure is 10-17 MPa, the thermoplastic setting temperature is 30°C, and the time is 24 hours.

[0045] Figure 2 This is a graph showing the diameter test results of the surgical suture prepared in Example 1 of the present invention. Figure 2 It can be seen that the diameter of the surgical suture prepared by the present invention is 0.066 mm, and the diameter specification meets the "7-0" surgical suture standard specified by the United States Pharmacopeia Committee USP.

[0046] Embodiment 2:

[0047] The content of Example 2 is basically the same as that of Example 1, except that:

[0048] In step S1: the raw material consists of a polymer matrix and a fiber-forming phase material, the polymer matrix is ​​PCL, and the fiber-forming phase material is PLA; PLA accounts for 20% of the total weight of PCL.

[0049] Embodiment 3:

[0050] The content of Example 3 is basically the same as that of Example 1, except that:

[0051] In step S1: the temperature settings of the twin-screw extruder from the barrel to the die are 80°C, 85°C, 85°C and 75°C respectively, and the speed of the twin-screw extruder is 90rpm; during hot stretching, the speed of the roller is 110rad / min; the hot stretching temperature is 75°C; the raw material is PCL.

[0052] Embodiment 4:

[0053] The content of Example 4 is basically the same as that of Example 1, except that:

[0054] In step S1: the speed of the twin-screw extruder is 90 rpm; during hot stretching, the speed of the roller is 100 rad / min. The raw material consists of a polymer matrix and a fiber-forming phase material, the polymer matrix is ​​PLCL, and the fiber-forming phase material is PLA; PLA accounts for 40% of the total weight of PLCL.

[0055] Embodiment 5:

[0056] The content of Example 5 is basically the same as that of Example 1, except that:

[0057] In step S1, the speed of the twin-screw extruder is 90 rpm; during the hot stretching, the speed of the roller is 110 rad / min. The raw material is PLA.

[0058] In step S3: the thermoplastic setting temperature is 65°C.

[0059] Embodiment 6:

[0060] The content of Example 6 is basically the same as that of Example 1, except that:

[0061] In step S3: the thermoplastic setting temperature is 45°C.

[0062] Embodiment 7:

[0063] The content of Example 7 is substantially the same as that of Example 1, except that:

[0064] In step S3: the thermoplastic setting temperature is 40°C.

[0065] Embodiment 8:

[0066] The content of Example 8 is basically the same as that of Example 1, except that:

[0067] In step S2: the temperature of the cold stretching treatment is 20° C., and the stretching rate of the cold stretching treatment is 5 mm / min;

[0068] In step S3: the thermoplastic setting temperature is 40°C.

[0069] Embodiment 9:

[0070] The content of Example 9 is basically the same as that of Example 3, except that:

[0071] In step S2: the temperature of the cold stretching treatment is 15° C., and the stretching rate of the cold stretching treatment is 3 mm / min;

[0072] In step S3: the thermoplastic setting temperature is 25°C.

[0073] The single-strand surgical suture prepared in Examples 1 to 5 of the present invention was tested for performance. At the same time, in order to verify the effect of the thermoplastic setting treatment under the protection of supercritical fluid on the performance of the surgical suture, the present invention conducted comparative experiments, namely, Comparative Examples 1 to 5. The contents of Comparative Examples 1 to 5 are basically the same as those of Examples 1 to 5, except that the filaments obtained after the cold stretching treatment in Comparative Examples 1 to 5 are single-strand surgical sutures, and the operation of step S3 is not performed (i.e., the filaments are not formed in the supercritical fluid CO 2 The filaments are subjected to thermoplastic shaping treatment under protection). The performance of the single-strand surgical sutures prepared in Examples 1 to 5 and Comparative Examples 1 to 5 was tested and compared with the existing commercial single-strand catgut suture (Comparative Example 6). The results are shown in Table 1.

[0074] Table 1 Performance test results of surgical sutures prepared in Examples 1 to 5

[0075]

[0076] As shown in Table 1, by comparing the embodiment with the comparative example, it can be seen that after supercritical CO 2 Atmosphere thermoplastic shaping, the ultimate tensile stress and elastic modulus of suture are improved, and the elongation at break is slightly reduced. Comparing Example 5 with Example 3, it can be seen that PLA has higher ultimate tensile stress and elastic modulus, but lower elongation at break. PLA and PCL are blended in situ fiberization (Example 2 and Comparative Example 2), in which PLA acts as a fiberization phase, and the ultimate tensile stress and elastic modulus of suture can be improved (Example 3 and Comparative Example 3). The addition of PLCL can improve the elongation at break of PLA (Example 4 and Example 5). Further, a small amount of PLCL is added to PCL / PLA as a processing aid, and PLCL can play a good capacity-increasing effect, improves the interface between PCL and PLA, and further improves the ultimate tensile stress (Example 1 and Example 2). Finally, Example 1, as the optimal component, is compared with the commercial catgut suture of Comparative 6, and has a higher ultimate tensile stress on the basis of similar elastic modulus and elongation at break.

[0077] In order to verify the effect of cold stretching treatment on the crystallinity of surgical sutures, the present invention takes the single-strand surgical suture prepared in Example 1 as an example to study the crystallization state of the surgical suture under different supercritical fluid thermoplastic setting treatment times; at the same time, the present invention also provides a comparative example 7 that is not subjected to cold stretching treatment.

[0078] The content of Comparative Example 7 is as follows:

[0079] A method for processing a single-strand surgical suture comprises the following steps:

[0080] S1: Dry the raw materials for preparing surgical sutures and mix them evenly, and melt blend them through a twin-screw extruder; the temperature settings of the twin-screw extruder from the barrel to the die are 170°C, 190°C, 190°C and 180°C, respectively, and the speed of the twin-screw extruder is 80rpm. After the blend exits the die of the twin-screw extruder, a high-speed roller is used for heat stretching to obtain primary fiber filaments with a diameter specification that meets the 7-0 standard for surgical sutures. The primary fiber filaments are cooled in a water bath and then wound and collected on a roller. During the heat stretching, the speed of the roller is 90rad / min; the temperature of the heat stretching is 180°C.

[0081] The raw material consists of a polymer matrix, a fiber-forming phase material and a processing aid, wherein the polymer matrix is ​​PCL, the fiber-forming phase material is PLA, and the processing aid is PLCL; PLA accounts for 20% of the total weight of PCL, and PLCL accounts for 5% of the total weight of PCL.

[0082] S2: Fix the two ends of the nascent fiber filament with a clamp (the distance between the two clamps is 1.1 times the original length of the filament in that direction), and then 2 The filament is subjected to thermoplastic setting treatment under protection to obtain a single-strand surgical suture, wherein the thermoplastic setting temperature is 30° C. and the time is 24 hours.

[0083] The crystallization state of the single-strand surgical suture prepared in Example 1 and Comparative Example 7 during the supercritical fluid thermoplastic shaping process is shown in the figure below: Figure 3 shown.

[0084] Depend on Figure 3 It can be seen that compared with Comparative Example 7, after cold stretching treatment, the macromolecules in the suture thread of Example 1 are oriented, inducing oriented crystallization; moreover, with the supercritical CO 2 The extension of the thermoplastic setting treatment time under the atmosphere significantly increased the crystallinity. This shows that the cold stretching treatment can induce the macromolecular orientation crystallization in the suture line, and the supercritical CO 2 Thermoplastic setting treatment can further improve the crystallinity of macromolecular materials, thereby enhancing the tensile strength of sutures.

[0085] The results of the mechanical property comparison of the single-strand surgical sutures prepared in Example 1 and Comparative Example 7 are shown in Table 2.

[0086] Table 2 Comparison of mechanical properties of single-strand surgical sutures prepared in Example 1 and Comparative Example 7

[0087]

[0088] As shown in Table 2, after cold drawing, under the same specifications, the ultimate tensile stress of Example 1 is increased by more than 6 times, the elastic modulus is increased by 4 times, and the elongation at break is reduced by 7 times compared with that of Comparative Example 7.

[0089] In order to verify the effect of cold stretching treatment on the mechanical properties of surgical sutures, the present invention takes the single-strand surgical suture preparation method recorded in Comparative Example 5 as an example, and respectively detects the ultimate tensile stress of the filaments obtained after hot stretching and cold stretching treatment in Comparative Example 5 and the ultimate tensile stress of the nascent fiber filaments obtained only by hot stretching treatment. It was found that the ultimate tensile stress of the filaments obtained after hot stretching and cold stretching treatment can reach 400.02MPa, but the ultimate tensile stress of the nascent fiber filaments obtained only by hot stretching treatment is only 53.06MPa. This shows that cold stretching treatment can greatly improve the mechanical properties of surgical sutures.

[0090] The above embodiments are intended to illustrate the essential content of the present invention, but are not intended to limit the protection scope of the present invention. Those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a single-strand surgical suture, characterized in that: The following steps are involved: S1: melt-blending raw materials for preparing surgical sutures and then heat-stretching them to obtain primary fiber filaments, wherein the raw materials include a polymer matrix, and the polymer matrix is ​​PCL, polylactic acid or PLCL; S2: cold-stretching the primary fiber filaments along the fiber orientation direction so that the diameter of the primary fiber filaments after cold-stretching meets the diameter specification of the surgical suture, and then removing the tensile load to obtain filaments; S3: Fixing the two ends of the filament with a clamp, and then performing thermoplastic shaping treatment on the filament under the protection of a supercritical fluid to obtain a single-strand surgical suture, wherein the supercritical fluid is carbon dioxide.

2. The preparation method according to claim 1, characterized in that: In step S3, the thermoplastic setting temperature is 25-45° C. and the time is 24 hours.

3. The preparation method according to claim 2, characterized in that: In step S3, the pressure of the supercritical fluid is 10-17 MPa.

4. The preparation method according to any one of claims 1 to 3, characterized in that: In step S1, the temperature of melt blending is 70-200°C; the temperature of heat stretching is 70-200°C.

5. The preparation method according to claim 4, characterized in that: In step S2, the temperature of the cold stretching treatment is 15-25°C; the stretching ratio of the cold stretching treatment is 1.2-3, and the stretching rate is 1-5 mm / min.

6. The preparation method according to claim 5, characterized in that: The raw materials also include fiber-forming phase material, and the fiber-forming phase material accounts for 5% to 40% of the total weight of the polymer matrix.

7. The preparation method according to claim 6, characterized in that: The raw materials also include processing aids, which account for 1 to 10% of the total weight of the polymer matrix.

8. The preparation method according to claim 7, characterized in that: The fiber-forming phase material is polylactic acid; and the processing aid is PLCL.

9. A surgical suture prepared by the preparation method according to any one of claims 1 to 8.

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