A wireless electro-stimulating carbon nanotube surgical suture for promoting tendon healing

Abstract

The present application relates to a kind of radio stimulation carbon nanotube surgical suture for promoting tendon healing and its preparation method and application, the carbon nanotube surgical suture is formed by the drafting, washing, drying and twisting of multiple carbon nanotube composite fibers.The carbon nanotube surgical suture of the present application has good electrical conductivity, flexibility, tensile strength and suture operation performance, can respond to external electromagnetic field, and produce electric stimulation in the local tendon injury through human coupling and capacitive coupling related mechanism, thereby promoting tenocyte proliferation migration, collagen fiber deposition and orderly arrangement, improve the structure repair quality and mechanical function recovery level after tendon injury.

Description

Technical Field

[0001] This invention belongs to the field of medical suture materials technology, and specifically relates to a radio-stimulated carbon nanotube surgical suture for promoting tendon healing. Background Technology

[0002] Tendons are important dense connective tissues connecting skeletal muscles and bone tissue. Their main function is to transmit the mechanical force generated by muscle contraction and maintain limb movement. Due to the long-term high tension and repetitive stretching, tendons are prone to rupture or tearing in sports injuries, sharp object cuts, traffic accidents, degenerative diseases, and surgical-related injuries. After tendon injury, surgical suturing is usually required to restore its anatomical continuity. However, compared with tissues such as skin and muscles, tendon tissue has a lower cell density, relatively insufficient blood supply, and a slower metabolic rate, resulting in limited spontaneous repair capacity after injury. This often leads to slow healing, disordered collagen fiber arrangement, scar formation, tendon adhesions, and re-rupture. Therefore, how to promote high-quality tendon healing while providing reliable mechanical fixation is a crucial problem that urgently needs to be solved in the field of tendon repair.

[0003] Existing medical sutures used for tendon closure mainly include nylon, polypropylene, polyester, polyethylene, polydioxanone, polylactic acid absorbable sutures, and ultra-high molecular weight polyethylene sutures. These sutures can meet the mechanical fixation requirements of tendon closure to a certain extent, but their function is primarily limited to passive support, making it difficult to actively regulate cellular behavior and the regenerative microenvironment at the site of tendon injury. During tendon healing, the migration, proliferation, and differentiation of tendon cells and tendon-derived stem / progenitor cells, as well as the synthesis and remodeling of the extracellular matrix, are crucial for the restoration of tendon mechanical properties. Traditional sutures lack the ability to effectively regulate these biological processes, thus failing to meet the functional recovery requirements in the repair of complex tendon injuries.

[0004] Electrical stimulation, as an important physical and biological regulatory tool, has been shown to influence membrane potential, ion channel opening, calcium ion signaling, cell migration direction, cell proliferation, and extracellular matrix synthesis in various cells. For tendon repair, appropriate intensity of electrical stimulation holds promise for promoting tendon cell activity, regulating collagen deposition and arrangement, and enhancing tissue remodeling in the injured area, thereby improving tendon healing quality. However, current electrical stimulation therapies typically rely on external leads, electrode pads, implantable electrodes, or dedicated power supply devices, which present challenges such as complex operation, high risk of infection, poor patient compliance, difficulty in long-term application to deep injury sites, and the potential need for secondary surgery for removal. Especially in tendon suturing scenarios, ideal electrical stimulation materials should simultaneously possess good suture mechanical properties, flexibility, knot stability, tissue compatibility, and local electrical stimulation function.

[0005] Carbon nanotubes possess excellent electrical conductivity, mechanical strength, and aspect ratio, making them important candidate materials for constructing conductive fibers and flexible bioelectronic materials. Wet spinning can assemble carbon nanotubes into continuous fibers, giving them both conductive networks and mechanical load-bearing capacity. However, in practical medical suture applications, pure carbon nanotube fibers may still suffer from insufficient fiber structural stability, processability, knotting performance, and long-term service stability.

[0006] Therefore, there is an urgent need to develop a functional surgical suture that can provide the high-strength mechanical support required for tendon suture and generate electrical stimulation at the injury site based on wireless power supply. This would enable continuous or phased electrical modulation of the tendon injury site without implanting a power source or adding complex wire connections, thereby promoting tendon tissue healing and mechanical function recovery. Summary of the Invention

[0007] To address the problems of existing tendon suture materials primarily serving a dynamic fixation function and lacking active bioelectric regulation capabilities, as well as the reliance on external leads or implanted power sources and the complexity of clinical applications of existing electrical stimulation devices, this invention provides a radio-stimulated carbon nanotube surgical suture for promoting tendon healing, along with its preparation method and applications.

[0008] This invention provides a radio-stimulated carbon nanotube surgical suture for promoting tendon healing. The suture is formed from multiple carbon nanotube composite fibers through stretching, washing, drying, and twisting. The carbon nanotube composite fibers are obtained by combining carbon nanotubes and polyimide. The radio-stimulated carbon nanotube surgical suture utilizes the conductive properties of carbon nanotubes to give the suture conductivity and flexible electrical response capabilities. Figure 3 As shown.

[0009] The radio-stimulated carbon nanotube surgical suture can respond to external electromagnetic fields through electromagnetic induction and capacitive coupling, and generate electrical stimulation between the suture and the local tissue of the tendon injury.

[0010] The radio-stimulated carbon nanotube surgical suture has a multi-strand twisted structure, which is used to improve the tensile strength, flexibility, knotting stability and suturing performance of the suture.

[0011] Depend on Figure 1 and Figure 2As shown, the core working principle of the radio-stimulated carbon nanotube surgical suture of this invention is as follows: Utilizing the excellent conductivity of carbon nanotube fibers and the difference in dielectric properties and electrical response between the suture and human tissue, under the influence of an external electromagnetic field, a potential difference is formed between the suture and the local tissue of the tendon injury through electromagnetic induction and capacitive coupling, thereby generating radio-stimulation in the tendon injury area. This electrical stimulation can act on tendon repair-related cells and the local regenerative microenvironment, promoting tendon cell proliferation and migration, extracellular matrix deposition, orderly arrangement of collagen fibers, and restoration of tendon mechanical properties.

[0012] Depend on Figure 4 As shown, the present invention also provides a method for preparing radio-stimulated carbon nanotube surgical sutures for promoting tendon healing, comprising the following steps: S1. Disperse carbon nanotubes in chlorosulfonic acid and stir to obtain a carbon nanotube dispersion; S2. Add polyimide powder to the carbon nanotube dispersion and mix evenly to obtain a dispersion system; then, under continuous stirring, add dry sodium nitrite powder in batches to the above dispersion system, and exhaust the tail gas in a fume hood. After the reaction is completed, filter and collect the product, wash it with deionized water until the filtrate is neutral, and then freeze dry it to obtain pretreated carbon nanotubes. S3. The pretreated carbon nanotubes are redispersed in chlorosulfonic acid and stirred to obtain carbon nanotube spinning solution; S4. The carbon nanotube spinning solution is extruded into a coagulation bath through a spinneret, causing the spinning solution to undergo phase transformation and solidify to form carbon nanotube composite fibers. S5. The obtained carbon nanotube composite fibers are continuously stretched and washed with water to remove residual solvent and improve fiber orientation. S6. After drying the washed carbon nanotube composite fibers, twist them to obtain radio-stimulated carbon nanotube surgical sutures for promoting tendon healing.

[0013] Preferably, the solid content of carbon nanotubes in the carbon nanotube dispersion in step S1 is 0.1-3 wt%, more preferably 0.5-1.5 wt%, and even more preferably 0.9 wt%.

[0014] Preferably, the stirring time in step S1 is 1-4 days, more preferably 2 days.

[0015] Preferably, the amount of polyimide added in step S2 is 1-20% of the mass of carbon nanotubes, more preferably 3-10%, and even more preferably 5%. The polyimide is used to improve the structural stability, fatigue resistance, tensile strength, and sewing stability of the carbon nanotube composite fiber.

[0016] Preferably, the amount of sodium nitrite added in step S2 is 0.1-20% of the mass of carbon nanotubes, and more preferably 1-10%.

[0017] Preferably, the solid content of carbon nanotubes in the carbon nanotube spinning solution in step S3 is 0.1-3 wt%, more preferably 0.5-1.5 wt%, and even more preferably 0.9 wt%.

[0018] Preferably, the stirring time in step S3 is 3-7 days, more preferably 4-5 days.

[0019] Preferably, the spinneret in step S4 is a multi-hole spinneret, and the number of holes in the multi-hole spinneret is 2-30, more preferably a ten-hole spinneret.

[0020] Preferably, the coagulation bath in step S4 is an acetone coagulation bath.

[0021] Preferably, the continuous drawing in step S5 is completed by a multi-roller drawing system, and more preferably by a five-roller drawing system.

[0022] Preferably, the twisting in step S6 is completed by a twisting machine, and carbon nanotube surgical sutures with different twists are obtained by adjusting the twisting speed, so as to control the tensile strength, elongation at break, flexibility, surface roughness and electrical stimulation output performance of the suture; the twist range is less than 400 r / m.

[0023] The present invention also provides the application of radio-stimulated carbon nanotube surgical sutures for promoting tendon healing in the preparation of medical suture materials for tendon injury repair.

[0024] Preferably, the tendon injury includes at least one of tendon rupture, partial tendon tear, or tendon defect. After the radio-stimulated carbon nanotube surgical suture is used to suture the tendon injury site, it provides electrical stimulation to the injured area under the action of an external electromagnetic field to promote tendon cell proliferation and migration, collagen fiber deposition, orderly arrangement of collagen fibers, and restoration of tendon mechanical properties.

[0025] Beneficial effects (1) The radio-stimulated carbon nanotube surgical suture of the present invention has both suture fixation and electrical stimulation therapy functions. It can not only provide mechanical fixation for tendon rupture as a surgical suture, but also generate electrical stimulation at the site of tendon injury under the action of external electromagnetic field, thereby actively regulating the tendon healing process.

[0026] (2) This invention utilizes the excellent conductivity of carbon nanotubes to give the suture good conductivity and flexible electrical response. Compared with traditional insulated sutures, this suture can participate in the regulation of the local electrical microenvironment, providing electrical stimulation cues for tendon injury repair.

[0027] (3) The present invention improves the structural stability, mechanical strength and processing stability of carbon nanotube composite fibers by modifying them with polyimide, making them more suitable for suturing and repairing high-tension tissues such as tendons.

[0028] (4) The present invention uses porous wet spinning, multi-roller drawing and twisting process to make carbon nanotube composite fibers form an oriented, multi-strand and adjustable twist structure, which is beneficial to improve the tensile strength, knotting stability, flexibility and sewing performance of the suture.

[0029] (5) The radio-stimulated carbon nanotube surgical suture of the present invention does not require the implantation of batteries or percutaneous leads. It can achieve local radio stimulation through the action of external electromagnetic fields, reducing the risk of infection, operational complexity and secondary removal risk of traditional electrical stimulation devices.

[0030] (6) The radio-stimulated carbon nanotube surgical suture of the present invention can promote tendon cell proliferation and migration, collagen fiber deposition and orderly arrangement of collagen fibers, thereby helping to improve the quality of structural repair and mechanical function recovery after tendon injury. Attached Figure Description

[0031] Figure 1 This is a schematic diagram illustrating the principle of how the radio-stimulated carbon nanotube surgical suture prepared in this invention, used to promote tendon healing, generates electrical stimulation at the site of tendon injury under the action of an external electromagnetic field.

[0032] Figure 2 The circuit diagram illustrates the principle of the radio-stimulated carbon nanotube surgical suture prepared in this invention for promoting tendon healing, which generates electrical stimulation at the site of tendon injury under the action of an external electromagnetic field.

[0033] Figure 3 This is a schematic diagram of the structure of the radio-stimulated carbon nanotube surgical suture prepared according to the present invention for promoting tendon healing.

[0034] Figure 4 This is a schematic diagram illustrating the preparation process of the radio-stimulated carbon nanotube surgical suture for promoting tendon healing, as described in this invention.

[0035] Figure 5 The image shows the scanning electron microscope results of the carbon nanotube surgical sutures with different twists in Example 1.

[0036] Figure 6 Figure 1 shows the tensile properties of carbon nanotube surgical sutures with different twists in Example 1; Figure a shows the stress-strain curves of sutures with twists of 0, 200 r / m, and 400 r / m; Figure b shows the fatigue curve of the suture with a twist of 200 r / m.

[0037] Figure 7The graph shows the effect of radio-stimulated carbon nanotube surgical sutures prepared in Examples 1, 1, 2 and 3 for promoting tendon healing on the proliferation and migration ability of cultured tendon cells in vitro.

[0038] Figure 8 The images show the immunofluorescence staining results of tendon cells after treatment in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3.

[0039] Figure 9 The images show the HE and Masson staining results of rat Achilles tendon tissues after treatment in Examples 1, 1, 2, and 3.

[0040] Figure 10 The image shows the arrangement of collagen fibers in the Achilles tendon of rats after treatment in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3.

[0041] Figure 11 Figure 1 shows the biomechanical test results of the Achilles tendon of rats after treatment in Example 1 and Comparative Example 2. Figure 2a shows the statistical graph of the maximum load on the Achilles tendon of rats in different treatment groups at different times; Figure 2b shows the statistical graph of the stiffness of the Achilles tendon of different rats at different times. Detailed Implementation

[0042] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0043] The present invention will be further described in detail below with reference to the embodiments.

[0044] The raw materials used in the embodiments of this invention are sourced from the following sources: Carbon nanotubes (CNTs) were purchased from Jiangsu Tiannai Technology Co., Ltd.

[0045] Chlorosulfonic acid was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0046] Polyimide (PI) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0047] Sodium nitrite was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0048] Acetone was purchased from Beijing Tongguang Fine Chemical Co., Ltd.

[0049] The deionized water is the standard deionized water used in the laboratory.

[0050] Example 1 This embodiment provides a method for preparing radio-stimulated carbon nanotube surgical sutures for promoting tendon healing, including the following steps: S1. Carbon nanotubes were dispersed in chlorosulfonic acid and stirred for 2 days to obtain a carbon nanotube dispersion with a solid content of 0.9 wt%. S2. Add polyimide powder (5% of the carbon nanotube mass) to the carbon nanotube dispersion and mix evenly to obtain a dispersion system. Then, under continuous stirring, slowly add 5% of the carbon nanotube mass of dry sodium nitrite powder to the dispersion system in batches, and exhaust the tail gas in a fume hood. After the reaction is completed, collect the product by filtration, wash it with deionized water until the filtrate is neutral, and then freeze dry it to obtain pretreated carbon nanotubes. S3. The pretreated carbon nanotubes are redispersed in chlorosulfonic acid and stirred for 4-5 days to obtain a carbon nanotube spinning solution with a solid content of 0.9 wt%. S4. The carbon nanotube spinning solution is extruded into an acetone coagulation bath through a ten-hole spinneret, so that the spinning solution undergoes phase transformation and solidifies to form carbon nanotube composite fibers. S5. The obtained carbon nanotube composite fibers are continuously stretched by a five-roller stretching system and thoroughly washed with deionized water to remove residual solvent and improve fiber orientation. S6. After drying the washed carbon nanotube composite fibers, twist them using a twisting machine to control the twist at 200 r / m, thus obtaining radio-stimulated carbon nanotube surgical sutures for promoting tendon healing.

[0051] This embodiment also provides a method for applying radio-stimulated carbon nanotube surgical sutures to promote tendon healing, as detailed below: A rat model of Achilles tendon transection was established. The transectioned Achilles tendon was sutured using radio-stimulated carbon nanotube surgical sutures. An electromagnetic field was generated by connecting a radio frequency / microwave signal generator (MODEL 835) to a power amplifier (LZY-22+) / (ATA-7050, Antexin). Rats were exposed to the electromagnetic field at a distance of 30–40 cm from the transmitter (23.8 dBm, 50 Hz) for 2 hours daily, allowing the sutures to provide radio-stimulated treatment to the Achilles tendon injury site to promote tendon tissue repair.

[0052] Example 2 The difference from Example 1 is that a twisting machine was used for the final twisting process, and the twist was controlled to be 0 r / m to obtain a low-twist radio-stimulated carbon nanotube surgical suture.

[0053] Example 3 The difference from Example 1 is that a twisting machine was used for the final twisting process, and the twist was controlled at 400 r / m to obtain a high-twist radio-stimulated carbon nanotube surgical suture.

[0054] Comparative Example 1 The transverse Achilles tendon of rats was sutured using the radio-stimulated carbon nanotube surgical suture from Example 1. The rats were fed under normal conditions without electromagnetic field exposure.

[0055] Comparative Example 2 The transverse Achilles tendon of rats was sutured using commercially available tendon suture (Mousse 4-0 suture, 15×60 cm). The rats were housed under normal conditions and were not exposed to electromagnetic fields.

[0056] Comparative Example 3 The transverse Achilles tendon of rats was sutured using commercially available tendon sutures (Mousse 4-0 sutures, 15×60 cm). The rats were then exposed to an adjustable electromagnetic field for 2 hours daily to receive electromagnetic field exposure treatment.

[0057] Experiment 1 Structural and mechanical property testing of carbon nanotube surgical sutures with different twists: Low-twist, medium-twist (200 r / m), and high-twist carbon nanotube surgical sutures were prepared respectively. The surface morphology of the sutures was observed using a scanning electron microscope, and the maximum tensile strength of the sutures was tested using an electronic tensile tester.

[0058] Specific results are shown in Table 1 and Figure 5-6 .

[0059] Table 1 From Table 1 and Figure 5-6 The displayed data shows that: Depend on Figure 5 It can be seen that carbon nanotube surgical sutures with different twists can all form a continuous fiber structure. Among them, the medium twist group has a more uniform and dense fiber arrangement; the low twist group has a relatively loose structure; and the high twist group shows obvious fiber entanglement.

[0060] Depend on Figure 6 It can be seen that medium twist (200 r / m) carbon nanotube surgical sutures have the best tensile properties, and their maximum load-bearing capacity is significantly better than that of the low twist group and the high twist group, indicating that a moderate degree of twisting is beneficial to improving the structural stability and mechanical properties of the suture.

[0061] Experiment 2 The effects of radio-induced carbon nanotube surgical sutures on the biological behavior of cultured tendon cells in vitro: Tendon cells were cultured in vitro and set up in the following four groups: Example 1: Adding carbon nanotube surgical sutures and applying external electromagnetic field stimulation.

[0062] Comparative Example 1: Adding carbon nanotube surgical sutures but without electromagnetic field stimulation; Comparative Example 2: Normal culture; Comparative Example 3: Applying external electromagnetic field stimulation; After a certain period of culture, scratch assay and immunofluorescence staining were used to evaluate tendon cell proliferation, migration, and phenotypic changes. Specific results are shown in [link to results]. Figure 7-8 .

[0063] Depend on Figure 7 It can be seen that the proliferation and migration capacity of tendon cells in the Example 1 group were significantly higher than those in other groups.

[0064] Depend on Figure 8 It can be seen that the expression level of tendon-related proteins was significantly increased in the group of Example 1, indicating that radio-stimulated carbon nanotube surgical sutures can promote tendon cell activation and the formation of tendon repair-related phenotypes.

[0065] Experiment 3 The effect of radiofrequency stimulation of carbon nanotube surgical sutures on Achilles tendon repair in rats: A rat Achilles tendon transection model was established, and the rats were treated using the methods described in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3, respectively.

[0066] Postoperatively, tissue samples were taken at specified time points. The Achilles tendon repair effect was evaluated using HE staining, Masson staining, collagen fiber arrangement analysis, and biomechanical testing. Specific results are detailed below. Figure 9-11 .

[0067] Depend on Figure 9 It can be seen that the Achilles tendon tissue in the Example 1 group had less inflammation, more complete tissue continuity, and more obvious collagen deposition; while the collagen arrangement in the other comparative groups was disordered and the infiltration of inflammatory cells was more obvious.

[0068] Depend on Figure 10 It can be seen that the collagen fibers in the first group of Examples are arranged more regularly and orderly, while the collagen fibers in the other groups are arranged more randomly.

[0069] Depend on Figure 11 It can be seen that the maximum load and mechanical recovery effect of the Achilles tendon tissue in Example 1 group were significantly better than those in other groups.

[0070] The above results demonstrate that the radio-stimulated carbon nanotube surgical suture in Example 1 can promote Achilles tendon tissue repair, improve collagen reconstruction quality and mechanical function recovery level under the action of an external electromagnetic field.

[0071] The specific embodiments of the present invention are merely illustrative of the invention and are not intended to limit it. Those skilled in the art can make modifications to these embodiments without contributing any inventive step after reading this specification, but such modifications are protected by patent law as long as they fall within the scope of the claims of the present invention.

Claims

1. A method for preparing radio-stimulated carbon nanotube surgical sutures for promoting tendon healing, characterized in that, Includes the following steps: S1. Disperse carbon nanotubes in chlorosulfonic acid and stir to obtain a carbon nanotube dispersion; S2. Add polyimide powder to the carbon nanotube dispersion and mix evenly to obtain a dispersion system; Subsequently, under continuous stirring, dry sodium nitrite powder was added to the above dispersion system in batches, and the tail gas was removed in a fume hood. After the reaction was completed, the product was collected by filtration and washed with deionized water until the filtrate was neutral. Then, it was freeze-dried to obtain pretreated carbon nanotubes. S3. The pretreated carbon nanotubes are redispersed in chlorosulfonic acid and stirred to obtain carbon nanotube spinning solution; S4. The carbon nanotube spinning solution is extruded into a coagulation bath through a spinneret, causing the spinning solution to undergo phase transformation and solidify to form carbon nanotube composite fibers. S5. The obtained carbon nanotube composite fibers are continuously stretched and washed with water to remove residual solvent and improve fiber orientation. S6. After drying the washed carbon nanotube composite fibers, twist them to obtain radio-stimulated carbon nanotube surgical sutures.

2. The preparation method according to claim 1, characterized in that, The solid content of carbon nanotubes in the carbon nanotube dispersion in step S1 is 0.1-3 wt%.

3. The preparation method according to claim 1, characterized in that, The amount of polyimide added in step S2 is 1-20% of the mass of the carbon nanotubes.

4. The preparation method according to claim 1, characterized in that, The amount of sodium nitrite added in step S2 is 0.1-20% of the mass of the carbon nanotubes.

5. The preparation method according to claim 1, characterized in that, The solid content of carbon nanotubes in the carbon nanotube spinning solution in step S3 is 0.1-3 wt%.

6. The preparation method according to claim 1, characterized in that, The spinneret in step S4 is a multi-hole spinneret; the coagulation bath is an acetone coagulation bath.

7. The preparation method according to claim 1, characterized in that, The continuous drawing in step S5 is accomplished by a multi-roller drawing system.

8. The preparation method according to claim 1, characterized in that, The twisting in step S6 is completed by a twisting machine, and carbon nanotube surgical sutures with different twists are obtained by adjusting the twisting speed; the twist range is less than 400 r / m.

9. The preparation method according to claim 1, characterized in that, The application of radio-stimulated carbon nanotube surgical sutures in step S6 in the preparation of medical suture materials for tendon injury repair.

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