Electroactive artificial ligament and methods of making and using the same

Abstract

The application provides an electroactive artificial ligament and a preparation method and application thereof, and belongs to the field of functional fibers.The electroactive artificial ligament comprises a shell knitted structure and a core piezoelectric fiber bundle.The shell knitted structure is formed by knitting of conductive yarn and elastic yarn.The core piezoelectric fiber bundle is arranged inside the shell knitted structure.The conductive yarn comprises a polyethylene terephthalate base yarn, a polydopamine intermediate layer and a conductive polymer layer.The elastic yarn is spirally or interlaced distributed along the axial direction of the artificial ligament.The conductive yarn is attached to the surface of the core piezoelectric fiber bundle to form an electrical connection.The core piezoelectric fiber bundle generates an electrical signal when compressed.The conductive yarn is used to conduct the electrical signal to the outside of the artificial ligament.The conductive yarn, the elastic yarn and the piezoelectric fiber are integrated in the core-shell structure artificial ligament, so that the artificial ligament not only provides mechanical support, but also has active bioelectricity regulation and control capability.

Description

Technical Field

[0001] This invention relates to the fields of tissue engineering, functional fibers and biomedical materials, specifically to an electroactive artificial ligament, its preparation method and application. Background Technology

[0002] Ligaments, especially the anterior cruciate ligament (ACL), play a crucial role in maintaining joint stability and motor function. ACL injuries are relatively common, and reconstruction is usually performed clinically using autologous or allogeneic transplantation. However, autologous transplantation presents challenges such as donor site injury and limited tissue availability, while allogeneic transplantation may carry risks including immune rejection, disease transmission, and decreased mechanical properties. Therefore, developing artificial ligaments that can replace natural ligaments is of significant clinical importance.

[0003] While existing artificial ligaments provide some mechanical support, they primarily function as passive fixation devices, lacking the ability to actively regulate tissue repair. This is especially true at the tendon-bone interface, where current artificial ligaments often face the following technical challenges: Healing between the artificial ligament and the bone tunnel relies mainly on passive fibrous scar tissue formation, lacking bioactive signals that induce osteogenic differentiation. This results in slow integration at the tendon-bone interface, insufficient bonding strength, and a high risk of ligament loosening or re-rupture. Existing materials lack piezoelectric response capabilities, failing to convert the mechanical stimulation generated by joint movement into electrical signals conducive to tissue regeneration. This necessitates external power sources or exogenous growth factors, increasing clinical complexity and safety risks. Some studies have attempted to introduce piezoelectric materials, but lack synergistic design with conductive pathways, preventing the effective transmission of localized piezoelectric signals to surrounding tissues and hindering the formation of a wide-area bioelectric stimulation microenvironment. Existing materials exhibit weak regulatory effects on nerve regeneration and angiogenesis, making it difficult to construct a neurovascular-bone coupling microenvironment conducive to bone integration, thus impacting long-term functional recovery. Furthermore, current functional modifications often sacrifice mechanical properties, failing to provide sufficient tensile strength and cyclic stability while simultaneously imparting stable electroactive output.

[0004] In view of this, it is necessary to design an electroactive artificial ligament, its preparation method, and its application to solve the above problems. Summary of the Invention

[0005] In view of the technical problems existing in the background art, this application provides an electroactive artificial ligament, its preparation method and application, aiming to solve the technical problems of low bone integration efficiency, slow interface healing and limited tissue reconstruction quality of existing artificial ligaments.

[0006] In a first aspect, this application provides an electroactive artificial ligament, comprising a shell braided structure and a core layer piezoelectric fiber bundle. The shell braided structure is formed by weaving conductive yarns and elastic yarns, and the core layer piezoelectric fiber bundle is disposed inside the shell braided structure. The conductive yarns comprise polyethylene terephthalate (PET) base yarns, a polydopamine intermediate layer covering the surface of the base yarns, and a conductive polymer layer covering the surface of the polydopamine intermediate layer. The conductive polymer layer is a poly(3,4-ethylenedioxythiophene) conductive layer. The core layer piezoelectric fiber bundle comprises 2 to 8 piezoelectric fibers. The piezoelectric fibers comprise a polyvinyl alcohol (PVA) matrix and glycine piezoelectric crystals dispersed in the PVA matrix. The elastic yarn is spirally or interwoven along the axial direction of the artificial ligament, and the elastic yarn is configured to generate radial contraction when the artificial ligament is subjected to axial tension, so as to apply compression to the core layer piezoelectric fiber bundle. The conductive yarn is bonded to the surface of the core layer piezoelectric fiber bundle to form an electrical connection. When the core layer piezoelectric fiber bundle is subjected to the compression, it generates an electrical signal. The conductive yarn is used to conduct the electrical signal to the outside of the artificial ligament.

[0007] As a further improvement to this application, the shell braiding structure includes 8 to 20 conductive yarns and 2 to 8 elastic yarns.

[0008] As a further improvement to this application, the elastic yarn is a thermoplastic polyurethane monofilament.

[0009] As a further improvement to this application, the glycine piezoelectric crystal is of β-glycine crystal form and / or γ-glycine crystal form.

[0010] Secondly, this application provides a method for preparing an electroactive artificial ligament as described in the first aspect, comprising the following steps: S1. Surface cleaning of polyethylene terephthalate-based yarn; S2. Immerse the cleaned polyethylene terephthalate base yarn in a dopamine solution to form a polydopamine layer on its surface; S3. The yarn obtained in step S2 is placed in a reaction solution containing 3,4-ethylenedioxythiophene monomer and oxidant for in-situ polymerization to obtain conductive yarn; S4. A polyvinyl alcohol solution and a glycine solution are mixed, and then subjected to wet spinning, salting out, freeze-thaw cycles, and drying to obtain piezoelectric fibers; S5. The conductive yarn, elastic yarn, and piezoelectric fiber obtained in step S3 are assembled into a core-shell artificial ligament by weaving, so that the elastic yarn is distributed in a spiral or interwoven manner along the axial direction of the artificial ligament.

[0011] As a further improvement of this application, in step S4, the mass concentration of the polyvinyl alcohol solution is 10-25%, and the mass concentration of the glycine solution is 5-15%; the volume ratio of the polyvinyl alcohol solution to the glycine solution is (0.5-2):1.

[0012] As a further improvement of this application, the coagulation bath of the wet spinning is a saturated ammonium sulfate solution, the salting out uses a sodium citrate solution with a concentration of 1~4 mol / L, and the freeze-thaw is carried out at -30~-10℃, with 2~5 freeze-thaw cycles.

[0013] Thirdly, this application provides the application of the electroactive artificial ligament as described in the first aspect in the preparation of implant materials for anterior cruciate ligament reconstruction, tendon-bone interface repair, and osseointegration.

[0014] The beneficial effects of this application are as follows: This application provides an electroactive artificial ligament, its preparation method, and its application. The electroactive artificial ligament includes a shell braided structure and a core layer piezoelectric fiber bundle. The shell braided structure is formed by weaving conductive yarns and elastic yarns, and the core layer piezoelectric fiber bundle is disposed inside the shell braided structure. The conductive yarn includes a polyethylene terephthalate (PET) base yarn, a polydopamine interlayer covering the surface of the base yarn, and a conductive polymer layer covering the surface of the polydopamine interlayer. The conductive polymer layer is a poly(3,4-ethylenedioxythiophene) conductive layer. The core layer piezoelectric fiber bundle... The piezoelectric fiber bundle comprises 2-8 piezoelectric fibers, each comprising a polyvinyl alcohol matrix and glycine piezoelectric crystals dispersed within the polyvinyl alcohol matrix. Elastic yarns are spirally or interwoven along the axial direction of the artificial ligament, configured to radially contract when the artificial ligament is subjected to axial tension, thereby compressing the core piezoelectric fiber bundle. Conductive yarns adhere to the surface of the core piezoelectric fiber bundle to form an electrical connection, generating an electrical signal when the core piezoelectric fiber bundle is compressed. The conductive yarns are used to conduct this electrical signal to the outside of the artificial ligament. This application integrates conductive yarns, elastic yarns, and piezoelectric fibers into a core-shell structured artificial ligament, enabling the artificial ligament to not only provide mechanical support but also possess active bioelectric regulation capabilities. This fabrication process is operable and scalable, suitable for textile processing and large-scale production.

[0015] The piezoelectric fibers in this application can generate electrical signals in situ under periodic mechanical stimulation from bodily movement, forming continuous bioelectric stimulation without the need for an external power source. The conductive yarns construct an efficient electronic transmission pathway, which can effectively conduct the electrical signals generated by the piezoelectric fibers to the tendon-bone interface, expanding the range of electrical stimulation. The core-shell structure design takes into account both axial tensile strength and piezoelectric output. The shell provides mechanical strength and resilience, while the core provides electrical activity, which can simultaneously promote osteogenic differentiation, nerve regeneration, and angiogenesis at the tendon-bone interface, thereby constructing a neurovascular-bone coupling microenvironment conducive to bone integration.

[0016] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0018] Figure 1 This is an electron microscope image of the conductive yarn provided in Embodiment 1 of this application; Figure 2 The energy spectrum of the conductive yarn provided in Embodiment 1 of this application; Figure 3 The electrical performance test results of the conductive yarn provided in Embodiment 1 of this application; Figure 4 This is an electron microscope image of a piezoelectric fiber provided in Embodiment 1 of this application; Figure 5 The energy spectrum of the piezoelectric fiber provided in Embodiment 1 of this application; Figure 6 This is a test diagram of the piezoelectric properties of the piezoelectric fiber provided in Embodiment 1 of this application; Figure 7 This is an electron micrograph of the electroactive artificial ligament provided in Embodiment 1 of this application; Figure 8 The mechanical performance test results of the electroactive artificial ligament provided in Embodiment 1 of this application; Figure 9 The cell compatibility test results of the electroactive artificial ligament provided in Example 1 of this application; Figure 10 This is a graph showing the expression of osteogenic induction-alkaline phosphatase in the electroactive artificial ligament provided in Example 1 of this application. Figure 11 Micro-CT bone integration image of the electroactive artificial ligament provided in Example 1 of this application one month after implantation; Figure 12 This is a diagram of electrical signals generated during knee flexion movement in vivo by the electroactive artificial ligament provided in Embodiment 1 of this application. Detailed Implementation

[0019] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0021] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0022] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0023] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0024] While existing artificial ligaments can provide some mechanical support, they primarily function as passive fixation devices and lack the ability to actively regulate tissue repair. This is especially true at the tendon-bone interface, where current artificial ligaments often suffer from low osseointegration efficiency, slow interface healing, and limited tissue reconstruction quality, making it difficult to achieve long-term functional recovery comparable to natural tissue. Furthermore, existing artificial ligaments lack effective signal transduction pathways, failing to convert mechanical stimulation into bioelectrical signals to promote osteogenic differentiation, neurovascularization, and osseointegration.

[0025] To address the technical problems of existing artificial ligaments that only provide mechanical support, lack active biological regulation functions, and have low integration efficiency at the tendon-bone interface, this application provides an electroactive artificial ligament, its preparation method, and its application. By integrating conductive yarns, elastic yarns, and piezoelectric fibers into a core-shell structured artificial ligament, the artificial ligament simultaneously possesses mechanical support, piezoelectric response, and conductive transmission capabilities. During bodily movement, it can generate and transmit electrical signals in situ to actively regulate osteogenic differentiation and neurovascular reconstruction at the tendon-bone interface, thereby enhancing the osseointegration capacity and long-term functional reconstruction effect of the artificial ligament.

[0026] In a first aspect, embodiments of this application provide an electroactive artificial ligament, comprising a shell braided structure and a core piezoelectric fiber bundle. The shell braided structure is formed by braiding conductive yarns and elastic yarns, and the core piezoelectric fiber bundle is disposed inside the shell braided structure. The conductive yarns include polyethylene terephthalate base yarns, a polydopamine intermediate layer covering the surface of the base yarns, and a conductive polymer layer covering the surface of the polydopamine intermediate layer. Among them, the elastic yarn is spirally or interwoven along the axial direction of the artificial ligament. The elastic yarn is configured to generate radial contraction when the artificial ligament is subjected to axial tension, so as to apply compression to the piezoelectric fiber bundle of the core layer. The conductive yarn is bonded to the surface of the core layer piezoelectric fiber bundle to form an electrical connection. When the core layer piezoelectric fiber bundle is compressed, it generates an electrical signal. The conductive yarn is used to conduct the electrical signal to the outside of the artificial ligament.

[0027] In the technical solution of this application embodiment, conductive yarn is used to construct the electrical signal transmission path in the artificial ligament, and elastic yarn is used to endow the shell with a certain recoverable deformation capability, and to convert the deformation into compression or squeezing of the piezoelectric fiber bundle in the core layer when the artificial ligament is stretched. The piezoelectric fiber bundle in the core layer, as a piezoelectric response unit, generates electrical signals when subjected to mechanical stimulation such as stretching, compression or bending. The electrical signals are led out through the conductive yarn in the shell layer and transmitted to the surrounding tissue outside the ligament, thereby forming a local bioelectric stimulation microenvironment and realizing in-situ electrical stimulation of the surrounding tissue.

[0028] Furthermore, in some embodiments, the conductive polymer layer is a poly(3,4-ethylenedioxythiophene) conductive layer.

[0029] In the technical solution of this application embodiment, the conductive yarn adopts a three-layer composite structure of polyethylene terephthalate (PET) base yarn, polydopamine (PDA) interlayer, and poly(3,4-ethylenedioxythiophene) (PEDOT) conductive layer. The PET base provides high-strength mechanical support, the PDA interlayer firmly anchors the conductive layer to the base surface through strong adhesion, and the PEDOT conductive layer endows the yarn with excellent electrical conductivity and stable electrochemical properties. This structure helps the conductive yarn to form a low-impedance, highly stable electrical connection with the surface of the core piezoelectric fiber bundle, thereby achieving efficient transmission of piezoelectric signals.

[0030] Furthermore, in some embodiments, the shell braided structure includes 8 to 20 conductive yarns and 2 to 8 elastic yarns; the core piezoelectric fiber bundle includes 2 to 8 piezoelectric fibers.

[0031] In the technical solution of this application embodiment, the shell layer helps to maintain sufficient mechanical support, while the elastic yarn can generate moderate and uniform radial contraction when stretched axially, thereby applying ideal compressive stress to the core layer; a sufficient number of conductive yarns helps the electrical signals generated by the piezoelectric fiber bundles in the core layer to be efficiently and stably exported, thereby achieving a synergistic balance between mechanical adaptability and electroactive output of the artificial ligament.

[0032] Furthermore, in some embodiments, the piezoelectric fiber comprises a polyvinyl alcohol matrix and glycine piezoelectric crystals dispersed in the polyvinyl alcohol matrix; the glycine piezoelectric crystals are β-glycine crystals and / or γ-glycine crystals.

[0033] In the technical solution of this application embodiment, the core layer piezoelectric fiber bundle includes a polyvinyl alcohol (PVA) matrix and glycine piezoelectric crystals. Through wet spinning, coagulation bath confinement, stretching orientation, salting out, and freeze-thaw treatment, glycine forms a piezoelectric active crystalline phase in the PVA network, mainly composed of β-glycine and accompanied by a small amount of γ-glycine, thereby obtaining piezoelectric fibers with both high mechanical and piezoelectric properties.

[0034] Furthermore, in some embodiments, the elastic yarn is a thermoplastic polyurethane monofilament.

[0035] In the technical solution of this application embodiment, the elastic yarn is a thermoplastic polyurethane (TPU) monofilament, which is interwoven and / or spirally distributed along the axial direction of the artificial ligament. When the artificial ligament is stretched as a whole, the TPU monofilament can drive the outer yarn to shrink radially, thereby squeezing the piezoelectric fiber bundle in the inner core layer and enhancing the piezoelectric output signal.

[0036] Secondly, embodiments of this application provide a method for preparing an electroactive artificial ligament, comprising the following steps: S1. Surface cleaning of polyethylene terephthalate-based yarn; Specifically, the PET yarn is ultrasonically cleaned 3-5 times with anhydrous ethanol and deionized water in sequence, and then dried for later use. S2. Immerse the cleaned polyethylene terephthalate base yarn in a dopamine solution to form a polydopamine layer on its surface; Specifically, the concentration of the dopamine solution is 1-3 mg / mL; the soaking time is 8-12 hours. S3. The yarn obtained in step S2 is placed in a reaction solution containing 3,4-ethylenedioxythiophene monomer and oxidant for in-situ polymerization to obtain conductive yarn; Specifically, the mass concentration of 3,4-ethylenedioxythiophene (EDOT) monomer in the reaction solution is 0.2~1.0%, and the concentration of oxidant FeCl3·6H2O is 0.01~0.05 g / mL; S4. A polyvinyl alcohol solution and a glycine solution are mixed, and then subjected to wet spinning, salting out, freeze-thaw cycles, and drying to obtain piezoelectric fibers; Specifically, the mass concentration of the polyvinyl alcohol solution is 10-25%, and the mass concentration of the glycine solution is 5-15%; the volume ratio of the polyvinyl alcohol solution to the glycine solution is (0.5-2):1; the coagulation bath for wet spinning is a saturated ammonium sulfate solution, and the salting out uses a sodium citrate solution with a concentration of 1-4 mol / L. Freeze-thaw cycles are carried out at -30 to -10℃, and the number of freeze-thaw cycles is 2-5. S5. The conductive yarn, elastic yarn, and piezoelectric fiber obtained in step S3 are assembled into a core-shell artificial ligament by weaving, so that the elastic yarn is distributed in a spiral or interwoven manner along the axial direction of the artificial ligament.

[0037] In the technical solution of this application embodiment, firstly, impurities on the surface of the PET substrate yarn are removed by ultrasonic cleaning, and then it is immersed in a dopamine solution to react, so that a uniform and dense PDA intermediate layer is formed on the yarn surface; the PDA-modified yarn is placed in a reaction solution containing EDOT monomer and oxidant for in-situ polymerization. With the good adhesion and reactivity of the PDA layer, a continuous and highly conductive PEDOT layer is generated in-situ on the yarn surface to obtain conductive yarn; on the other hand, PVA solution and glycine solution are mixed, wet-spun and then placed in a saturated ammonium sulfate coagulation bath for forming, and then citric acid is used... Sodium solution is used for salting out to promote glycine crystallization and form a β / γ piezoelectric crystal phase. The composite structure of PVA network and glycine crystal is stabilized by freeze-thaw cycles, and finally dried to obtain piezoelectric fibers. The above-mentioned conductive yarn, thermoplastic polyurethane elastic yarn and piezoelectric fibers are assembled into a core-shell structured artificial ligament through a braiding process, and the elastic yarn is distributed in a spiral or interwoven manner along the ligament axis. This method achieves reliable integration of a conductive shell with excellent mechanical properties and a piezoelectric active core layer through synergistic optimization of process parameters in each step, providing a repeatable and controllable technical path for the large-scale preparation of artificial ligaments.

[0038] Thirdly, embodiments of this application provide the application of an electroactive artificial ligament in the preparation of implantable materials for anterior cruciate ligament reconstruction, tendon-bone interface repair, and osseointegration.

[0039] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0040] Example 1 This embodiment provides a method for preparing an electroactive artificial ligament, including the following steps: S1. The PET yarn (100D / 48F yarn specification) is ultrasonically cleaned with anhydrous ethanol and deionized water three times in sequence (40 kHz, 25℃), 15 min each time, to remove surface impurities and grease, and then dried in a vacuum drying oven at 60℃ for later use. S2. Prepare a dopamine solution with a concentration of 2 mg / mL and adjust the pH of the solution to 8.5. Immerse the cleaned PET yarn in the dopamine solution and shake it on a shaker for 10 hours. After taking it out, rinse it 5 times with deionized water and then vacuum dry it at 60℃ to obtain PET-PDA yarn with a polydopamine layer on the surface. S3. EDOT monomer and oxidant FeCl3·6H2O were dissolved in a 3:1 (v / v) mixture of anhydrous ethanol and deionized water, where the EDOT concentration was 0.4% (w / v) and the FeCl3·6H2O concentration was 0.02 g / mL. The yarn obtained in step S2 was placed in the reaction solution and reacted at room temperature for 12 h. It was then removed and washed five times alternately with deionized water and ethanol, and vacuum dried at 60 °C to obtain PET-PEDOT conductive yarn. The surface scanning electron microscopy results are shown below. Figure 1 As shown, the energy spectrum analysis is as follows: Figure 2 As shown, the surface roughness of the PET-PEDOT yarn increases, and sulfur characteristic signals appear, indicating that PEDOT has been successfully assembled onto the PET yarn surface and formed a continuous conductive layer. Further electrical performance tests were conducted on the PET-PEDOT conductive yarn, such as... Figure 3 As shown, PET-PEDOT conductive yarn has low impedance and high conductivity at 1kHz, as well as high charge storage capacity and charge injection capacity, making it suitable as a conduction path for piezoelectric signals in artificial ligaments. S4. Dissolve PVA in deionized water and stir at 95℃ for 5 hours to prepare a 20wt% PVA solution; separately dissolve glycine in deionized water to prepare a 10wt% glycine solution; mix 10mL of PVA solution with 10mL of glycine solution and stir until clear to obtain a PVA / Gly mixed solution. The mixed solution was loaded into a syringe and injected at a rate of 0.4 mL / min through an 18G needle into a saturated ammonium sulfate coagulation bath to form fibers. The nascent fibers were collected using a roller. The resulting fibers were then salted out in a 2 mol / L sodium citrate solution for 12 h. After removal, the fibers were rinsed three times with deionized water to remove residual salts. The salted-out fibers were then frozen at -20°C for 6 h, followed by thawing at room temperature for 2 h. This constituted one freeze-thaw cycle, which was repeated three times. The freeze-thawed fibers were then dried in a 60°C convection oven for 6 h to obtain PVA@Gly piezoelectric fibers. The scanning electron microscope (SEM) results of the piezoelectric fiber surface are shown below. Figure 4 As shown, the energy spectrum analysis is as follows: Figure 5 As shown, glycine has been successfully introduced into PVA fibers, and glycine mainly forms β-glycine crystals in the PVA matrix, accompanied by a small amount of γ-glycine crystals, thus endowing the fibers with piezoelectric activity. The piezoelectric properties of PVA@Gly fibers were tested using a piezoelectric response atomic force microscope and an open-circuit voltage testing system. Figure 6 As shown, a is the piezoelectric response curve, b is the curve of PVA fiber output voltage changing with time, and c is the curve of PVA@Gly fiber output voltage changing with time. It can be seen that PVA@Gly fiber can generate a stable piezoelectric response signal under periodic mechanical stimulation, making it suitable as a piezoelectric functional unit in artificial ligaments. S5. Artificial ligaments were braided using a 16-spindle braiding machine. Twelve rolls of PET-PEDOT conductive yarn and four rolls of TPU monofilament (0.3 mm in diameter) were evenly distributed on the braiding machine's yarn carrier. Four PVA@Gly piezoelectric fibers were passed through the center of the braiding machine as core threads. The braiding machine speed was set to 60 rpm, the braiding angle (angle between the yarn and the axis) to approximately 60°, and the traction speed to 0.1 m / min. This yielded a core-shell structured electroactive artificial ligament, denoted as the PPT-PG artificial ligament. The electron microscope image of the electroactive artificial ligament structure is shown below. Figure 7 As shown, a is an electron microscope image of the surface of the artificial ligament, and b is its cross-sectional view. It can be seen that the artificial ligament has a distinct core-shell structure, with the outer conductive yarn and TPU monofilament forming a woven shell, and the core layer piezoelectric fiber bundle located in the central region.

[0041] Example 2 This embodiment provides a method for preparing an electroactive artificial ligament. Compared with Example 1, the only difference is that the shell braiding structure consists of 8 conductive yarns and 2 elastic yarns, and the core piezoelectric fiber bundle consists of 2 piezoelectric fibers; the PVA solution concentration is 10%, the glycine solution concentration is 5%, and other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0042] Example 3 This embodiment provides a method for preparing an electroactive artificial ligament. Compared with Example 1, the only difference is that the shell braiding structure consists of 10 conductive yarns and 6 elastic yarns, and the core piezoelectric fiber bundle consists of 8 piezoelectric fibers; the PVA solution concentration is 25%, the glycine solution concentration is 15%, and other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0043] Comparative Example 1 Comparative Example 1 provides a method for preparing an electroactive artificial ligament. The only difference from Example 1 is that the core fiber is pure PVA fiber without the addition of glycine. That is, 12 rolls of PET-PEDOT conductive yarn, 4 rolls of TPU monofilament and 4 PVA fibers are woven to obtain a PPT-PVA artificial ligament.

[0044] Comparative Example 2 Comparative Example 2 provides a method for preparing an electroactive artificial ligament. Compared with Example 1, the only difference is that the conductive yarn is pure PET yarn without conductive modification, and the core fiber is pure PVA fiber without added glycine. That is, 12 rolls of PET yarn, 4 rolls of TPU monofilament and 4 PVA fibers are woven to obtain a PT-PVA artificial ligament.

[0045] The mechanical properties of the artificial ligaments obtained in Example 1 and Comparative Examples 1-2 were tested, such as... Figure 8 As shown, a is the tensile fracture stress-strain curve of the artificial ligaments provided in Example 1 and Comparative Examples 1-2, and b is the cyclic tensile curve of Example 1. It can be seen that the PPT-PG artificial ligament has mechanical properties that match those of the natural anterior cruciate ligament and maintains a high stress retention rate in the cyclic tensile test.

[0046] Comparative Example 3 Comparative Example 3 provides a method for preparing an electroactive artificial ligament. Compared with Example 1, the only difference is that the shell braided structure has no elastic yarn. Other experimental parameters and conditions are basically the same as those in Example 1, and will not be repeated here.

[0047] Comparative Example 4 Comparative Example 4 provides a method for preparing an electroactive artificial ligament. The only difference from Example 1 is that the piezoelectric fiber was not subjected to salting out and freeze-thaw treatment. Other experimental parameters and conditions are basically the same as those in Example 1, and will not be repeated here.

[0048] After weaving, each group of samples was cleaned, dried, and sterilized with ethylene oxide for later use.

[0049] The mechanical properties and piezoelectric output properties of each embodiment and comparative example are shown in Table 1.

[0050] Table 1. Performance test results of the examples and comparative examples. As shown in Table 1, Example 1 exhibits the best performance in piezoelectric output, while also demonstrating superior tensile strength and elongation at break. Example 2, due to its smaller number of conductive and elastic yarns and core fibers, shows relatively lower performance across various metrics. Comparative Example 1, with a core of pure PVA and no glycine, and Comparative Example 2, lacking both conductive modification and glycine in its core, both showed low piezoelectric output, demonstrating that both piezoelectric materials and conductive pathways are indispensable for achieving high electroactive output. Comparative Example 3, lacking elastic yarn, achieved a higher piezoelectric output than Example 2, but its lack of the radial contraction mechanism of elastic yarn resulted in severe signal attenuation under dynamic cyclic loading and the absence of ligament retraction ability, making it prone to loosening and failure within the body. Comparative Example 4, with its piezoelectric fibers that underwent no salting out or freeze-thaw cycles, showed acceptable piezoelectric output performance, but its fibers rapidly dissolved glycine crystals upon contact with water, resulting in almost complete loss of wet piezoelectric activity, accompanied by a sharp drop in mechanical strength and potential biosafety hazards.

[0051] In vitro evaluation of electroactive artificial ligaments: Rat bone marrow mesenchymal stem cells were seeded onto the surfaces of different groups of materials, and their cell compatibility was evaluated by CCK-8 and live / dead staining. Figure 9 As shown, both the PPT-PG group and the PPT-PVA group have good biocompatibility, with the PPT-PG group exhibiting a better trend in cell spreading and proliferation.

[0052] Bone marrow mesenchymal stem cells were cultured in osteogenic induction medium, and alkaline phosphatase staining and alizarin red staining were performed on days 7 and 14. Simultaneously, osteogenic-related markers such as COL-I, Runx2, OPN, and OCN were detected by qRT-PCR and immunofluorescence. Figure 10 As shown, the PPT-PG group exhibited higher ALP activity, stronger mineralization capacity, and higher expression levels of osteogenic-related genes and proteins, indicating that it possesses superior osteogenic induction ability.

[0053] Application of electroactive artificial ligaments in ACL reconstruction: An anterior cruciate ligament (ACL) reconstruction model was established using SD rats. After excision of the original ACL, bone tunnels were constructed in the femur and tibia. Artificial ligament samples were fixed within these tunnels and sutured in layers. Samples were harvested at 4 and 12 weeks post-surgery. Inflammatory response at the tendon-bone interface, new bone formation, macrophage polarization, and angiogenesis were analyzed using H&E staining, Masson staining, and immunofluorescence. The bone tunnel area and bone volume volume (BV) / total volume (TV) were assessed using Micro-CT. The bone regeneration results 4 weeks after implantation of the electroactive artificial ligament are as follows: Figure 11 As shown in the results, the PPT-PG group was superior to the control group in terms of inflammation control, interfacial bone formation, angiogenesis and bone integration.

[0054] The artificial ligament prepared in Example 1 was implanted into the knee joint of SD rats and connected to a signal acquisition device. Piezoelectric signal output was detected during simulated knee flexion and extension movements. Figure 12 As shown, the artificial ligament can generate detectable in-situ electrical signals under in vivo movement conditions, verifying its feasibility as a self-driven electroactive artificial ligament.

[0055] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. An electroactive artificial ligament, characterized in that, The device comprises a shell braided structure and a core layer piezoelectric fiber bundle. The shell braided structure is formed by weaving conductive yarns and elastic yarns, and the core layer piezoelectric fiber bundle is disposed inside the shell braided structure. The conductive yarns include polyethylene terephthalate (PET) base yarns, a polydopamine intermediate layer covering the surface of the base yarns, and a conductive polymer layer covering the surface of the polydopamine intermediate layer. The conductive polymer layer is a poly(3,4-ethylenedioxythiophene) conductive layer. The core layer piezoelectric fiber bundle includes 2 to 8 piezoelectric fibers, and the piezoelectric fibers include a polyvinyl alcohol (PVA) matrix and glycine piezoelectric crystals dispersed in the PVA matrix. The elastic yarn is spirally or interwoven along the axial direction of the artificial ligament, and the elastic yarn is configured to generate radial contraction when the artificial ligament is subjected to axial tension, so as to apply compression to the core layer piezoelectric fiber bundle. The conductive yarn is bonded to the surface of the core layer piezoelectric fiber bundle to form an electrical connection. When the core layer piezoelectric fiber bundle is subjected to the compression, it generates an electrical signal. The conductive yarn is used to conduct the electrical signal to the outside of the artificial ligament.

2. The electroactive artificial ligament according to claim 1, characterized in that, The shell braided structure includes 8 to 20 conductive yarns and 2 to 8 elastic yarns.

3. The electroactive artificial ligament according to claim 2, characterized in that, The elastic yarn is a thermoplastic polyurethane monofilament.

4. The electroactive artificial ligament according to claim 1, characterized in that, The glycine piezoelectric crystal is in the β-glycine crystal form and / or the γ-glycine crystal form.

5. A method for preparing an electroactive artificial ligament as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Surface cleaning of polyethylene terephthalate-based yarn; S2. Immerse the cleaned polyethylene terephthalate base yarn in a dopamine solution to form a polydopamine layer on its surface; S3. The yarn obtained in step S2 is placed in a reaction solution containing 3,4-ethylenedioxythiophene monomer and oxidant for in-situ polymerization to obtain conductive yarn; S4. A polyvinyl alcohol solution and a glycine solution are mixed, and then subjected to wet spinning, salting out, freeze-thaw cycles, and drying to obtain piezoelectric fibers; S5. The conductive yarn, elastic yarn, and piezoelectric fiber obtained in step S3 are assembled into a core-shell artificial ligament by weaving, so that the elastic yarn is distributed in a spiral or interwoven manner along the axial direction of the artificial ligament.

6. The method for preparing an electroactive artificial ligament according to claim 5, characterized in that, In step S4, the mass concentration of the polyvinyl alcohol solution is 10-25%, and the mass concentration of the glycine solution is 5-15%; the volume ratio of the polyvinyl alcohol solution to the glycine solution is (0.5-2):

1.

7. The method for preparing an electroactive artificial ligament according to claim 6, characterized in that, The coagulation bath for wet spinning is a saturated ammonium sulfate solution, the salting out uses a sodium citrate solution with a concentration of 1~4 mol / L, and the freeze-thaw cycle is carried out at -30~-10℃, with 2~5 freeze-thaw cycles.

8. The use of the electroactive artificial ligament according to any one of claims 1-4 in the preparation of implant materials for anterior cruciate ligament reconstruction, tendon-bone interface repair, and osseointegration.

Images