3D printing degradable biomimetic external tracheal stent and preparation method thereof

Abstract

The application provides a 3D-printed degradable external tracheal stent, which comprises an outer layer of high-modulus degradable material and an elastic inner layer of low-modulus degradable material, and is initially in a plate-shaped form prepared by 3D printing in an integrated manner, is shaped into a C-shaped cylindrical shape suitable for the tracheal wall after being enclosed by heat bending, and is connected in an axial sliding manner without being separated from each other through a sliding structure; the inner layer can slide and elastically reset in an axial reciprocating damping manner along with the tracheal wall, and can be coupled to deform in a radial and axial manner, and meanwhile, a double-curved surface structure is adopted for the inner and outer walls, and the original design of the functional layered structure and the interlayer follow-up coupled deformation can effectively imitate the natural physiological curvature and mechanical characteristics of the human trachea; and the application further provides a tracheal stent preparation method, which adopts 3D printing, heat bending shaping, sliding assembly, electrostatic spinning repair layer and sterile packaging processes, and solves the defects of the mechanical performance contradiction, single function and limited mass production of the prior art stent.

Description

Technical Field

[0001] This invention belongs to the field of medical device technology, specifically relating to a 3D-printed biodegradable biomimetic gas tube stent and its preparation method. Background Technology

[0002] The trachea is the core physiological passage of the human respiratory system. Its tracheal wall is composed of C-shaped cartilaginous rings, elastic fibers, smooth muscle, and mucosal ciliary tissue. According to the physiological environment of the trachea, the C-shaped cartilaginous rings mainly provide radial mechanical support to elastically maintain the airway's normal opening. Smooth muscle and connective tissue provide axial and radial elasticity, allowing the trachea to expand and contract appropriately with breathing and neck movements. The mucosal ciliary system completes the airway's self-cleaning and defense functions. From a mechanical perspective, its overall structure achieves a balance between maintaining patency and adapting to radial and axial dynamic movements. In clinical practice, factors such as congenital developmental abnormalities, chest and neck trauma, surgical resection of airway tumors, and long-term inflammatory degenerative changes can easily cause the loss of the number and thickness of tracheal cartilaginous rings, disordered arrangement of elastic fibers, and large-area defects in the tracheal wall tissue. This can lead to tracheomalacia, airway collapse, and stenosis, inducing persistent dyspnea, intractable cough, and wheezing. In severe cases, it can be life-threatening.

[0003] The current mainstream clinical solution is the implantation of artificial tracheal stents, which are divided into endovascular stents and external stents. Intravascular stents are prone to causing excessive granulation tissue growth, mucus retention, and airway obstruction, and they lack the ability to provide external support and repair for long tracheal wall defects. External tracheal stents, on the other hand, have become the preferred clinical approach because they can wrap and support the airway from the outside, do not encroach on the airway lumen, and are suitable for repairing long defects. Most existing external tracheal stents adopt a simulated C-shaped cylindrical structure and can be divided into non-degradable stents (metallic or non-metallic) and biodegradable stents. Compared with non-degradable stents, biodegradable stents have advantages such as better biocompatibility, absorbability without retention in the body, lower risk of infection, no need for secondary surgery for removal, and superior biomimetic mechanical properties, making them a research and development trend.

[0004] The invention patent with application number CN202511779728.3 discloses a biodegradable modular tracheal stent, which includes several coaxially arranged annular ribs and a mesh-like soft body connecting the ribs. The soft body enables the axial length of the stent body to be adjustable and axially bent. It also includes a connecting part, which includes a first connector at both ends of the stent body and a second connector that matches the first connector. The first connector and the second connector cooperate to achieve axially detachable connection between multiple stent bodies. This invention mainly uses the soft body coaxially arranged between the ribs to achieve the purpose of axial bending deformation of the stent. However, the axial bending deformation technology of this stent mainly relies on the elastic material properties of the soft body. Moreover, the adjacent ribs are spaced apart. Under mechanical stress such as repeated airway movement and friction of secretions, they are prone to radial misalignment or lateral dislocation in the cross-sectional direction due to inconsistent radial shear stress. This can lead to a decrease in the performance of the soft body material or even breakage. The overall structural stability of the stent is somewhat insufficient.

[0005] In summary, existing biodegradable tracheal stents still have certain technical shortcomings:

[0006] 1) Mechanical performance contradictions: Existing stent structures cannot balance the repetitive contradictions between radial support and expansion and contraction, as well as axial expansion and contraction and bending compressive stress. They cannot match the dynamic coupling deformation characteristics brought about by human breathing fluctuations, coughing vibrations, neck movements and children's growth and development. Postoperative complications such as stent structure instability, slippage and dislocation, stress concentration at both ends, abnormal granulation tissue proliferation, and local compression necrosis are likely to occur.

[0007] 2) The structure and function are singular, resulting in large clinical surgical trauma and complicated procedures. The stent design focuses on mechanical support function and does not consider the tissue repair of tracheal wounds or the replacement of mucosal defects. For cases with large-area defects in the tracheal wall or missing mucosal layer, it is necessary to first perform free flap or autologous tissue transplantation to repair the tracheal wound, and then implant the stent for fixation. The treatment is completed in two independent surgeries, which has a long operation cycle, high operation difficulty, large trauma and increased probability of postoperative infection.

[0008] 3) Molding and manufacturing processes struggle to balance large-scale mass production with personalized clinical adaptation. Mature biodegradable polymer tracheal stents primarily utilize 3D printing to achieve gradient pores and heterogeneous porous structures for molding and preparation, with electrospinning and coating used to complete the overall fabrication. However, each patient's CT image data must be precisely modeled and printed individually to achieve personalized customization, making it difficult to standardize and mass-produce for adaptation. This limits its industrial mass production, commercialization, and clinical adoption.

[0009] In summary, conventional techniques in this field cannot overcome the aforementioned mechanical contradictions, limited functionality, and production constraints. There is an urgent need to research a new structural design for an external tracheal stent that is compatible with both mass production and personalized manufacturing processes. Summary of the Invention

[0010] This application provides a 3D-printed biodegradable biomimetic tracheal stent and its preparation method to solve the problems of mechanical contradictions, limited functionality, and limited mass production of existing tracheal stents.

[0011] To address the aforementioned technical problems, this application provides a 3D-printed biodegradable biomimetic gas duct external support, fabricated through a functional layered configuration, interlayer sliding coupling deformation, and standardized prefabrication and hot bending shaping processes. This support achieves a dynamic coupling deformation biomimetic functional balance of radial mechanical support and expansion / contraction, as well as axial expansion / contraction and bending compliance, and is fabricated using standardized 3D printing and hot bending forming. The support includes:

[0012] The outer layer is made of a high-modulus biodegradable material, and the inner layer is made of a low-modulus biodegradable material. Both layers are initially 3D printed as a single pre-formed plate, which is then heat-bent and shaped into a C-shaped tube to fit the tracheal wall. The outer layer has several radial through-holes for sutures to pass through. The outer layer includes a middle section and extensions connecting the two ends of the middle section along its axial direction. The axial length of the middle section is not less than the axial length of the inner layer. It also includes biodegradable sliding structures on the inner wall of the middle section and the outer wall of the inner layer, enabling a continuous axial sliding connection between the outer and inner layers. During implantation, the sutures... The outer layer is sutured to the tracheal wall through the through-hole on the extension segment, and the inner layer is sutured to the tracheal wall through the through-hole on the middle segment. That is, the sutures of the outer layer and the inner layer to the tracheal wall do not cross each other, so as to avoid obstructing their sliding function. After the operation, the inner layer can accompany the tracheal wall to perform axial reciprocating damped sliding and elastic reduction, axial bending and circumferential torsion, and radial and axial expansion and contraction coupling deformation relative to the middle segment. The unique structural design of this functional layered configuration and interlayer follow-up coupling deformation can effectively adapt to the physiological and mechanical environment of the tracheal stent and solve the mechanical contradiction between the radial support and axial compliance of the stent.

[0013] The outer layer, made of a high-modulus biodegradable material, primarily provides stable radial mechanical support to prevent tracheal collapse and serves as a mounting base for the inner layer and sliding structure. The initial outer layer is designed as a plate-like structure, facilitating rapid 3D standardized printing. Compared to three-dimensional printing, this plate-like planar form offers higher yield and printing efficiency. Several through-holes facilitate the passage of sutures when the inner layer is sutured to the tracheal wall, preventing the outer layer from being sutured together. Suturing the inner and outer layers together would restrict the sliding function of the inner layer. Furthermore, it reduces the weight of the stent and lessens pressure on surrounding tracheal tissues. The through-holes are preferably in the form of square or diamond-shaped holes, with the diameter determined based on the balance requirements of the radial mechanical support strength of the outer layer and the suture area of ​​the inner layer. The C-shaped cylindrical design adapts to the physiological structure of the trachea, facilitating stent implantation and fixation, while also reserving space for radial expansion of the trachea, preventing excessive pressure on the trachea from the stent.

[0014] The inner layer, made of a low-modulus biodegradable material with good elasticity, functions primarily to conform to the tracheal wall. It dynamically couples with the tracheal wall, allowing for axial sliding, expansion, contraction, and radial expansion, reducing friction between the stent and the tracheal wall and preventing damage. After being heat-bent and enclosed, the inner layer slides coaxially with the middle section, forming a double-layer stent structure. The inner diameter of the inner layer matches the outer diameter of the tracheal wall, ensuring a tight fit after implantation and enabling dynamic coupling deformation. Simultaneously, the axial length of the inner layer is less than that of the middle section, preventing sutures between the inner layer and the extended section of the tracheal wall, and allowing for sliding space within the inner layer.

[0015] The core purpose of the sliding structure design is to resolve the mechanical contradictions of existing stents and achieve an organic combination of strong radial support in the outer layer and axial flexible compliance in the inner layer. When a person breathes, coughs, or moves their neck, the trachea will undergo axial expansion, contraction, bending, and radial expansion coupled deformation. The inner layer moves synchronously with the tracheal wall. The deformation stress is offset by the low modulus elastic deformation of the inner layer itself and the sliding combination with the outer layer, avoiding relative friction and stress concentration between the stent and the tracheal wall, thereby reducing the risk of postoperative complications such as slippage, dislocation, and granulation tissue hyperplasia.

[0016] Furthermore, the sliding structure includes a slide rail, a sliding rib, and a damping elastomer;

[0017] The slide rails are installed on the inner wall of the middle section along the axial sliding direction. There are at least three slide rails, which are arranged at circumferential intervals along the middle section. The purpose of designing three or more slide rails is to ensure the sliding stability between the inner layer and the middle section, so as to avoid circumferential displacement and jamming of the inner layer during the sliding process, and to ensure that the inner layer can slide smoothly along the axial direction. The length of the slide rail is adapted to the axial length of the middle section, and the extension sections at both ends of the slide rail form a natural limiting structure.

[0018] The sliding ribs, which slide in conjunction with the slide rails, are set on the outer wall of the inner layer. The number and position of the sliding ribs correspond to the number and position of the slide rails, ensuring that each sliding rib can be accurately embedded in the corresponding slide rail to achieve stable sliding. Since the length of the inner layer is less than the length of the middle section, after the sliding ribs and slide rails are installed and matched, a relative sliding space is formed between the two ends of the sliding ribs and the extension section.

[0019] The damping elastomer is filled in the sliding space and is used to elastically constrain the reciprocating sliding length of the sliding edge. The specific sliding length can be reasonably set according to different application scenarios for children and adults. The damping elastomer is always in contact with the end of the adjacent sliding edge, effectively realizing the axial sliding control and elastic reset of the sliding edge, avoiding collision between the sliding edge and the extension section, and improving the stability of the sliding structure.

[0020] Furthermore, the sliding edge includes a base extending along the sliding direction of the inner layer and embedded in the inner layer at several intervals, and sub-sliding edges fixedly set on the base, that is, segmented into several sub-sliding edges, which can disperse the sliding stress of the sliding edge, avoid stress concentration between the sliding edge and the slide rail, and improve the elastic compliance of the sliding edge; the length of the sub-sliding edge along the sliding direction is 5~10mm, and the spacing between adjacent sub-sliding edges is not less than 4mm. The setting of its length dimension and adjacent spacing dimension can enable the sliding edge to adapt to the radial expansion and contraction deformation of the inner layer during the sliding process, avoid the sliding edge from hindering the radial and axial expansion and contraction deformation of the inner layer, and avoid the sliding edge from breaking or getting stuck due to the deformation of the inner layer; at the same time, the spacing between adjacent sub-sliding edges can reserve deformation space for the inner layer and avoid stress concentration.

[0021] Furthermore, when the outer layer is plate-shaped, the slide rail is a rectangular groove with an open top. When the outer layer is hot-bent into a C-shaped cylindrical shape on one side of the slide rail, both groove walls of the rectangular groove slide rail are bent and inclined in opposite directions, naturally forming a V-shaped groove slide rail with a small opening and a large bottom. The cross-sectional shape of the sliding edge matches the V-shaped groove slide rail. This innovative design cleverly combines the transformation of the outer layer from plate-shaped to C-shaped cylindrical shape, enabling the rectangular groove to simultaneously transform into a V-shaped groove without secondary processing.

[0022] Furthermore, it also includes a repair layer fixed to the inner wall of the inner layer. The repair layer is a composite patch prepared by electrospinning. The composite patch is loaded with anti-inflammatory factors and epithelial cell induction regeneration factors. It is used to cover the tracheal wall wound to achieve early anti-inflammatory effect and continuously induce mucosal epithelial regeneration. It has the function of flap or autologous tissue transplantation repair, thus forming a three-layer scaffold application modality. It can realize the combination of flap transplantation repair and scaffold implantation into one, effectively solving the single function problems of existing technology such as long cycle, high operation difficulty, large trauma and high postoperative infection probability and infection risk.

[0023] Furthermore, to address the technical challenge of matching the stent degradation sequence with tissue repair needs, the degradation cycles of the repair layer, inner layer, and outer layer increase in a gradient from the inside out. The tracheal wound repair process is mainly divided into three stages: inflammation control, mucosal regeneration, and tissue stabilization. The gradient time-series degradation design can achieve precise matching between the degradation rate of each stent layer and each stage of tissue repair.

[0024] Furthermore, to mimic the natural physiological curvature and mechanical characteristics of the human trachea, the axial cross-section of both the outer wall of the outer layer and the inner wall of the inner layer is wavy. The wavy inner wall and the outer wall combine to form a hyperboloid structure, which facilitates the fit between the outer layer and the soft tissue around the trachea and the fit between the inner layer and the tracheal wall, enhancing the anti-displacement effect of the stent while avoiding pressure damage.

[0025] Furthermore, to avoid the need for a second surgery to remove it, the biodegradable material of the tracheal stent is a biodegradable polymer material, including at least two of the following: polyhydroxyalkanoate (PHA) and its copolymers, polycaprolactone (PCL) and its copolymers, polyglycolic acid (PGA) and its copolymers, polybutylene succinate (PBS) and its copolymers, polyvinyl alcohol (PVA) and its copolymers, polylactic acid (PLA) and its copolymers, polylactic acid-glycolic acid copolymer (PLGA), and polydioxanone (PDO) and its copolymers. The specific material can be matched and selected according to the functional design needs such as different elastic moduli, mechanical properties and degradation rates.

[0026] This invention provides a method for fabricating a 3D-printed biodegradable biomimetic gas endovascular stent, achieving both large-scale mass production and personalized clinical customization, comprising the following steps:

[0027] S1. Pre-printing: Construct a three-dimensional model according to the preset structure and size parameters of the inner and outer layers. The outer layer printing material is selected as polycaprolactone (PCL)-chondrocyte mixture, and the inner layer printing material is selected as polydioxanone (PDO)-anti-inflammatory drug mixture. The outer layer is printed by fused deposition modeling (FDM) 3D printing and the inner layer is printed by solution extrusion (DIW) 3D printing, respectively. After shaping, a plate-shaped outer layer and inner layer are obtained.

[0028] S2. Hot bending and shaping: Based on the set support diameter, C-shaped opening size, and material softening temperature requirements, select the corresponding size of the molding die and the appropriate medical temperature-controlled heating tool for the softening temperature. The softening temperature of PCL is 60~70℃, and the softening temperature of PDO is 50~60℃ to ensure that the material is fully softened. During the bending and enclosing process, the printed plate-shaped outer or inner layer is attached to the molding die and slowly bent into a C-shape. Then, it is cooled and shaped. The cooling time is 15~30 minutes. After shaping, a C-shaped cylindrical outer and inner layer is obtained.

[0029] S3. Double-layer stent preparation: The outer and inner layers are slidably connected by sliding structures on the C-shaped outer and inner layers to ensure that the inner layer can achieve axial reciprocating damped sliding without disengaging from the outer layer along the axial direction. The sliding length is controlled within a set range, thus obtaining a double-layer stent.

[0030] S4. Spinning Repair Layer: A sheet-like repair layer is prepared using an electrospinning process. The raw material is GelMA hydrogel loaded with vascular endothelial growth factor (VEGF) and endothelial progenitor cells. After spinning, a sheet-like repair layer of a set thickness is obtained.

[0031] S5. Preparation of three-layer scaffold: Apply gelatin-chitosan composite quick-setting adhesive to the inner wall of the inner layer of the double-layer scaffold obtained in step S3. The coating thickness is 10~50μm. Then, attach the sheet-like repair layer to the inner wall of the inner layer and press and hold for 50~90s to complete the fixation between the repair layer and the inner layer, thus obtaining a three-layer scaffold.

[0032] S6. Post-processing and packaging: The double-layer stent obtained in step S3 or the triple-layer stent obtained in step S5 is sterilely dried to remove moisture and impurities from the surface of the stent. After drying, it is packaged with medical sterile packaging materials to obtain the finished double-layer or triple-layer stent.

[0033] In step S4, an appropriate amount of gelatin microspheres can be added to the hydrogel. The gelatin microspheres can act as a sustained-release carrier for the factors, further prolonging the release time of anti-inflammatory factors and epithelial cell-inducing regeneration factors, thereby improving the wound repair effect.

[0034] The beneficial effects of the embodiments of this application, which differ from the prior art, are as follows:

[0035] 1. The tracheal stent of this application provides stable radial mechanical support through a high-modulus outer layer and achieves axial flexible compliance through a low-modulus elastic inner layer. The two are connected by a sliding structure. The inner layer can achieve axial reciprocating damped sliding and elastic reset along with the tracheal wall, as well as radial and axial expansion and contraction coupling deformation. This effectively counteracts the stress generated by the dynamic deformation of the trachea, avoids displacement and stress concentration between the stent and the tracheal wall, solves the mechanical contradiction of existing stents that cannot balance rigidity and flexibility, reduces the incidence of postoperative complications such as stent dislocation, granulation tissue proliferation, and local compression necrosis, and adapts to the tracheal morphology and dynamic deformation needs of different patients.

[0036] 2. The sliding structure of the tracheal stent of this application adopts an innovative design of segmented sliding ribs, adaptive V-shaped sliding fit, and damping elastomer filling the sliding space. The segmented sliding ribs can disperse sliding stress and adapt to the axial reciprocating damping sliding and reset of the inner layer, as well as the radial and axial expansion and contraction coupling deformation. The V-shaped groove slide rail is cleverly combined with the thermal bending shape change of the outer layer, without the need for additional secondary processing. The damping elastomer can effectively realize the axial sliding control and compliant reset of the sliding ribs, and its structure has high stability.

[0037] 3. The repair layer of the tracheal stent in this application is loaded with anti-inflammatory factors and epithelial cell-inducing regeneration factors, which can directly cover the tracheal wall wound, achieving early anti-inflammatory and continuous mucosal regeneration. No secondary surgery is required for wound repair, effectively simplifying the surgical procedure, shortening the surgical cycle, reducing the difficulty of surgical operation, patient trauma and postoperative infection probability. It is especially suitable for complex cases with large-area defects in the tracheal wall and missing mucosal layer.

[0038] 4. The tracheal stent of this application adopts a hyperboloid biomimetic structure design of inner and outer walls, which conforms to the natural physiological curvature and mechanical characteristics of the human trachea. It can accurately adapt to the anatomical shape of the trachea, ensuring that the stent fits tightly to the outer wall of the trachea after implantation and the force is evenly distributed. This not only enhances the anti-displacement effect of the stent and ensures the stability of tracheal support, but also effectively reduces the pressure and stimulation of the stent on the normal tissues around the trachea, and improves the implantation fit and biocompatibility.

[0039] 5. The tracheal stent of this application has a hollowed-out perforated structure on the outer layer. The structure is regular and mechanically balanced, and it has good cutability and sutureability. It can be slidably connected with the inner layer to form a double-layer stent mode, or a repair layer can be added to form a triple-layer stent mode. It can also be used alone as a single-layer stent mode. Its application mode can be flexibly switched, which makes it convenient for surgeons to quickly select the appropriate mode according to the location and length of the tracheal lesion and individual anatomical differences during surgery, so as to meet the personalized surgical needs of different patients and effectively improve the convenience and adaptability of surgery.

[0040] 6. The tracheal stent fabrication of this application initially presents the outer and inner layers as a pre-fabricated 3D-printed plate, enabling standardized mass printing, reducing manufacturing costs, and facilitating industrial mass production. Simultaneously, through heat bending and shaping, the length and width dimensions of the plate-shaped outer and inner layers can be precisely cut to meet the patient's individual size requirements, achieving personalized clinical fit. The product can be delivered as a finished stent in a cylindrical assembly form or as a semi-finished product in a plate form, solving the technical problem of balancing mass production and personalized customization in existing stents, and improving the stent's versatility. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0042] Figure 1 This is an exploded structural diagram of an embodiment of the 3D-printed biodegradable biomimetic gas tube external support of the present invention;

[0043] Figure 2 This is a schematic diagram of an embodiment of the outer plate-like form of the present invention;

[0044] Figure 3 for Figure 2 A schematic diagram of the A-A section structure;

[0045] Figure 4 for Figure 2 Schematic diagram of the B-B section structure;

[0046] Figure 5 for Figure 4 Schematic diagram of the C-shaped cylindrical structure after hot bending;

[0047] Figure 6 This is a schematic diagram of another embodiment of the outer C-shaped cylindrical form of the present invention;

[0048] Figure 7 This is a schematic diagram of an embodiment of the inner plate-like morphology of the present invention;

[0049] Figure 8 for Figure 7 A schematic diagram of the C-C section structure in the diagram;

[0050] Figure 9 for Figure 7 A schematic diagram of the right-side view structure in the diagram;

[0051] Figure 10 for Figure 9 Schematic diagram of the C-shaped cylindrical structure after hot bending;

[0052] Figure 11 This is a radial cross-sectional view of an embodiment of the double-layer support structure of the present invention;

[0053] Figure 12 This is an axial cross-sectional view of an embodiment of the double-layer support structure of the present invention;

[0054] Figure 13 This is an assembly structure rendering of an embodiment of the double-layer bracket of the present invention;

[0055] Figure 14 This is a radial cross-sectional view of an embodiment of the three-layer support structure of the present invention;

[0056] Figure 15 This is a schematic diagram of the axial cross-sectional structure of an embodiment of the three-layer support of the present invention.

[0057] The markings in the diagram are as follows: 1—outer layer, 11—middle section, through hole—111, 12—extension section, 13—flexible membrane layer, 14—fiber filament, 2—inner layer, 3—repair layer, 4—sliding structure, 41—slide rail, 42—sliding ridge (421—base, 422—sub-sliding ridge), 43—damping elastomer, 5—tracheal wall. Detailed Implementation

[0058] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It is understood that the specific embodiments described herein are only for explaining this application and not for limiting it. Furthermore, it should be noted that, for ease of description, only the parts related to this application are shown in the accompanying drawings, not all structures. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0059] In the description of this application, it should be understood that the terms "center," "axial," "radial," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0060] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0061] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0062] 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 mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0063] This application provides a 3D-printed biodegradable biomimetic tracheal stent and its implantation method, which solves the problem that existing tracheal stents cannot balance the contradictions between repeated dynamic radial support and expansion, as well as axial expansion and bending compressive stress, and the problem of large-scale mass production and individualized clinical adaptation.

[0064] Example 1

[0065] like Figures 1-13 As shown in Figure 15, a 3D-printed biodegradable biomimetic gas duct scaffold includes a high-modulus biodegradable outer layer 1 and a low-modulus biodegradable elastic inner layer 2. Both outer layer 1 and inner layer 2 are initially 3D-printed as a single prefabricated plate. The outer layer 1 uses a polycaprolactone (PCL)-chondrocyte mixture, with PCL having a molecular weight of 80,000~100,000 and chondrocytes added at an amount of 5 × 10⁻⁶. 5The inner layer 2 uses a mixture of polydioxanone (PDO) and dexamethasone, with PDO having a molecular weight of 40,000-50,000 and dexamethasone added at 0.5 mg / g. The plate-like outer layer 1 and inner layer 2 are softened by heating and bent into a C-shaped cylindrical form suitable for the tracheal wall 5. The outer layer 1 has several radial through-holes, including a middle section 11 and extension sections 12 integrally connected to both axial ends of the middle section 11. Preferably, the middle section 11 is a frame structure with several rectangular grid-like perforated through-holes 111. The through-holes 111 can be arranged according to the overall structure, such as... Figure 2 or Figure 6 As shown, without limitation, and the axial length of the intermediate segment 11 is not less than the axial length of the inner layer 2, the extension segment 12 is used for suturing and connecting the tracheal wall 5, and also includes a flexible membrane layer 13 disposed on the inner wall of the extension segment 12 and a plurality of flexible fiber filaments 14 disposed on the flexible membrane layer 13. The flexible fiber filaments 14 are beneficial to improving the adsorption or adhesion between the extension segment 12 and the tracheal wall 5, enhancing the anti-displacement effect of the stent. The flexible membrane layer 13 can avoid rigid contact with the tracheal wall, and preferably, anti-proliferation, repair-promoting, and anti-inflammatory drug molecules are added to the material of the flexible membrane layer 13 to further improve the postoperative efficacy; also includes a flexible membrane layer 13 disposed on the inner wall of the intermediate segment 11. The outer wall of the inner layer 2 has a biodegradable sliding structure. The sliding structure 4 enables the outer layer 1 and the inner layer 2 to slide axially without separating. After connection, it becomes a finished double-layer bracket. The sliding space length of the inner layer 2 can be regarded as the length difference between the inner layer 2 and the middle section 11. In one embodiment, the finished product dimensions are as follows: the overall axial length of the double-layer bracket is 50mm, the inner diameter or channel diameter is 20mm, the C-shaped opening angle is 25°, the axial length of the middle section 11 is 34mm, the rectangular grid-shaped through hole 111 on the middle section 11 is 10mm×4mm, the axial length of the inner layer 2 is 30mm, and the axial length of the extension section 12 is 8mm.

[0066] During implantation, the outer layer 1 is sutured first. The extension segment 12 is the area where the outer layer 1 is sutured to the tracheal wall 5. The outer layer 1 and the tracheal wall 5 are sutured together through the through-hole 111 on the extension segment 12. Then, the inner layer 2 is sutured, passing through the through-hole 111 on the middle segment 11 to suture together with the tracheal wall 5. During the suturing process, it is necessary to avoid suturing the middle segment 11 and the inner layer 2 together. Postoperatively, the outer layer 1 provides the main radial mechanical support and overall structural stability of the stent. The inner layer 2 can undergo axial reciprocating damped sliding and repositioning, axial bending and circumferential torsion, and radial and axial expansion and contraction coupling deformation relative to the middle segment 11 along with the tracheal wall 5. The axial reciprocating damping sliding function of inner layer 2, combined with the elasticity and extensibility of its own material, can effectively adapt to the radial and axial dynamic and repetitive coupling deformation requirements of the tracheal wall 5. The axial bending, circumferential torsion, and radial expansion of inner layer 2 can be achieved by utilizing the elasticity and extensibility of its material. In summary, by adopting a functional layered configuration with double-layer sliding of inner layer 2 and outer layer 1, interlayer follow-up coupling deformation design, and the mechanical support of high-modulus outer layer 1 and the elasticity and extensibility of low-modulus inner layer 2, the decoupling of the overall mechanical support and compliant function of the stent is fundamentally achieved, thereby effectively adapting to the physiological and mechanical environment of the trachea.

[0067] In one preferred embodiment, the stent is designed to mimic the natural physiological curvature and mechanical characteristics of the human trachea, precisely adapting to the anatomical shape of the trachea. This ensures that the stent fits tightly against the tracheal wall 5 after implantation, with uniform stress distribution. The axial cross-sections of the outer wall of the outer layer 1 and the inner wall of the inner layer 2 are both wavy. The wavy inner wall and outer wall together form a hyperboloid structure. This hyperboloid structure also facilitates the fit between the outer layer 1 and the soft tissues around the trachea, as well as the fit between the inner layer 2 and the tracheal wall 5, enhancing the stent's anti-displacement effect. At the same time, it further buffers the stress between the stent and the tracheal wall 5, preventing pressure damage.

[0068] In one preferred embodiment, the biodegradable material of the tracheal stent is a biodegradable polymer material, including at least two of the following: polyhydroxyalkanoate (PHA) and its copolymers, polycaprolactone (PCL) and its copolymers, polyglycolic acid (PGA) and its copolymers, polybutylene succinate (PBS) and its copolymers, polyvinyl alcohol (PVA) and its copolymers, polylactic acid (PLA) and its copolymers, polylactic acid-glycolic acid copolymer (PLGA), and polydioxanone (PDO) and its copolymers. The inner layer 1 and the outer layer 2 have different elastic moduli. To meet functional design requirements such as mechanical properties and degradation rate adaptation, different materials are preferred for matching. To ensure the stability of the sliding connection structure, the sliding structure 4 can be made of the same material as the outer layer 1. The entire structure is made of biodegradable material, which can form long-term temporary support for the narrowed trachea and maintain the normal airway diameter. After the stent is implanted, it can adapt to the tracheal tissue repair and regeneration process. As the body's own tracheal tissue gradually grows in and completes remodeling and repair, the stent can be gradually degraded and absorbed in sync, without the need for a second surgery to remove it, effectively avoiding the trauma risk and postoperative complications caused by a second surgery.

[0069] Regarding the manufacturing of the product in this embodiment, the finished product quality or pass rate and printing efficiency of the plate-shaped outer layer 1 and inner layer 2 3D printing are significantly higher than those of the C-shaped cylindrical three-dimensional form. Furthermore, plate-shaped planar printing eliminates the need for the waste of materials such as structural supports required for three-dimensional printing, resulting in lower costs and suitability for mass production. It is easy to imagine that dedicated shaping aids can be configured to facilitate hot bending, such as temperature-controlled heating sources and standardized conforming molds. Specifically, the product deliverable can be a standard prefabricated plate-shaped outer layer 1 and inner layer 2 semi-finished product, which simplifies packaging and storage and is suitable for personalized customization needs. Clinically, the dimensions of the plate-shaped outer layer 1 and inner layer 2 can be precisely cut according to the size data of tracheal CT images, and then, with the aid of hot bending, a personalized double-layer stent can be quickly shaped and slidably connected. Alternatively, the product deliverable can be an assembled double-layer stent finished product, with finished products divided into standard series specifications according to different lengths and diameters. When clinical needs arise, the appropriate model can be selected and applied directly based on its suitability, thus effectively solving the problem of existing technologies struggling to balance mass production and personalized customization.

[0070] Example 2

[0071] This embodiment, based on Embodiment 1, further provides a three-layer support structure design scheme, as detailed below:

[0072] like Figures 1-15As shown, to address the technical issues of existing stents having limited function and requiring secondary surgery to repair tracheal wounds, a repair layer 3 is also included, fixed to the inner wall of the inner layer 2. Repair layer 3 is a composite patch prepared by electrospinning, loaded with anti-inflammatory factors and epithelial cell-inducing regeneration factors. This is used to cover the tracheal wall 5 wound to achieve early anti-inflammatory effects and continuously induce mucosal epithelial regeneration. The electrospinning process can prepare a fibrous membrane structure with uniform pore size and large specific surface area. This structure has a high similarity to the structure of human mucosal tissue, facilitating adhesion to the tracheal wall 5 wound and promoting factor loading and sustained release. The loaded anti-inflammatory factors... Inflammatory factors and epithelial cell-inducing regeneration factors, such as dexamethasone and other anti-inflammatory factors, can be used to achieve early anti-inflammatory effects after covering the tracheal wall wound, inhibiting the inflammatory response of the wound, reducing granulation tissue proliferation, and creating a favorable microenvironment for mucosal regeneration. Epithelial cell-inducing regeneration factors, such as vascular endothelial growth factor (VEGF) and keratinocyte growth factor (KGF), can be used to continuously induce the proliferation and differentiation of tracheal mucosal epithelial cells, promote wound healing, and achieve regeneration and repair of the tracheal mucosa, thereby forming a three-layer scaffold structure that eliminates the need for secondary surgery for wound repair, reducing surgical trauma and infection risks.

[0073] As a preferred embodiment, nano-hydroxyapatite can be added to the repair layer 3. Nano-hydroxyapatite is similar to the inorganic components of human tissue and has excellent biocompatibility and bioactivity. It can enhance the cell adhesion ability of the repair layer 3, promote the proliferation and differentiation of epithelial cells, further accelerate the repair of mucosal wounds, and improve the mechanical stability of the repair layer 3.

[0074] In a preferred embodiment, the degradation cycles of the repair layer 3, inner layer 2, and outer layer 1 increase in a gradient from the inside to the outside. The repair layer 3 directly adheres to the wound surface, making it suitable for degradation to be completed in the early stages of wound healing, thus avoiding long-term retention that could affect mucosal regeneration. The inner layer 2 is suitable for gradual degradation after mucosal regeneration, providing short-term support for the mucosal tissue, while gradually losing its function as the tracheal tissue recovers. The outer layer 1 needs to provide long-term stable radial support for the tracheal tissue until the tracheal cartilage and connective tissue are repaired and have self-supporting capabilities, after which it gradually degrades, ensuring that the scaffold can always provide effective support and protection throughout the entire repair process. The gradient degradation can be achieved by selecting biodegradable materials with different degradation rates, combined with existing publicly available technologies, and adjusting parameters such as the molecular weight and porosity of the material, which will not be elaborated here, thereby achieving a gradient increase in the degradation cycle.

[0075] In practice, the degradation cycle of each layer can be adjusted according to the patient's age and differences in tissue repair ability: for pediatric patients, the degradation cycle of repair layer 3, inner layer 2 and outer layer 1 should be adapted to the characteristics of children's rapid tissue repair and rapid growth and development; for elderly patients, it should be adapted to the characteristics of elderly patients' slow tissue repair.

[0076] Example 3

[0077] This embodiment, based on Embodiment 1, further provides a sliding structure design scheme, as detailed below:

[0078] like Figures 1-11 As shown, the sliding structure 4 includes a slide rail 41, a sliding rib 42, and a damping elastomer 43;

[0079] Four slide rails 41 are installed on the inner wall of the intermediate section 11 along the axial sliding direction. They are arranged circumferentially along the intermediate section 11, with one slide rail on each side near the C-shaped opening of the intermediate section 11 and two slide rails spaced at the center of the intermediate section 11 to prevent circumferential displacement or jamming of the inner layer during sliding and to ensure smooth axial sliding of the inner layer 2. The length of the slide rail 41 is adapted to the axial length of the intermediate section 11, that is, the slide rail 41 runs through the entire intermediate section 11. The extension sections 12 at both ends of the slide rail 41 form a natural end limiting structure, eliminating the need for additional limiting structures. The specific number of slide rails 41 can be adjusted according to the diameter of the stent. For stents with smaller diameters, such as those suitable for pediatric patients, three slide rails can be installed. For stents with larger diameters, five slide rails can be installed to ensure sliding stability and the stability of the connection structure between the inner layer 2 and the outer layer 1.

[0080] The sliding rib 42, which slides in conjunction with the slide rail 41, is set on the outer wall of the inner layer 2. The number and position of the sliding rib 42 correspond to the number and position of the slide rail 41, ensuring that each sliding rib 42 can be accurately embedded in the corresponding slide rail 41 to achieve stable sliding. Since the length of the inner layer 2 is less than the length of the middle section 11, after the sliding rib 42 and the slide rail 41 are installed and matched, a relative sliding space is formed between the two ends of the sliding rib 42 and the extension section 12. This sliding space provides a sliding length range for the axial reciprocating damped sliding of the sliding rib 42.

[0081] The damping elastomer 43, made of a biodegradable material, is filled within the sliding space. It elastically constrains the axial sliding length of the sliding rib 42 by 5 mm, and the damping elastomer 43 always contacts the end of the adjacent sliding rib 42, effectively controlling the axial sliding of the sliding rib 42 and providing elastic reset. The damping elastomer 43 can be made of flexible materials such as biodegradable hydrogel, ensuring biocompatibility with the overall stent material. It can degrade synchronously with the stent, leaving no residue in the body. The axial sliding length of the sliding rib 42 can be set according to the different tracheal sizes required for children and adults, aiming to adapt to the axial expansion and contraction of the human trachea during breathing, coughing, and neck movements. The damping elastomer 43 serves two purposes: firstly, it flexibly constrains the sliding length of the sliding rib 42; secondly, it provides elastic reset force after the sliding rib 42 slides, ensuring the stent always adheres to the tracheal wall 5 and preventing stent displacement due to excessive sliding of the sliding rib 42. Simultaneously, the damping elastomer 43 also acts as a buffer, reducing collisions between the sliding rib 42 and the extension segment 12, thus improving the stability of the sliding structure. The specific working principle is as follows: During the axial tensile deformation of the tracheal wall 5, when the deformation force is less than the sliding resistance of the sliding rib 42, the inner layer 2 uses its own elastic properties to elongate and adapt to the deformation of the tracheal wall 5. When the deformation force is greater than the sliding resistance of the sliding rib 42, the sliding rib 42 will drive the inner layer 2 to slide axially along with the tracheal wall 5. At this time, the damping elastic body 43 at one end of the sliding rib 42 is compressed, and the damping elastic body 43 at the other end is stretched. When resetting, the damping elastic bodies 43 at both ends of the sliding rib 42 form an elastic resultant force, which helps the inner layer 2 to return to its original position, greatly avoiding displacement friction between the tracheal wall 5 and the inner layer 2.

[0082] Example 4

[0083] like Figures 7-12 , Figure 11 As shown, this embodiment, based on embodiment three, further provides a design scheme for the sliding edge 42 and the slide rail 41, as detailed below:

[0084] The sliding rib 42 adopts a segmented structural design, including a number of spaced bases 421 extending along the sliding direction of the inner layer 2 and built into the inner layer 2, and sub-sliding ribs 422 fixedly connected to the bases 421. The segmented design can disperse sliding stress, avoid stress concentration between the sliding rib 42 and the slide rail 41, and improve the compliance of the sliding rib 42. Specifically, the base 421 is built into the inner layer 2 and extends along the sliding direction of the inner layer 2, which plays the role of fixing the sub-sliding ribs 422, while enhancing the connection strength between the sub-sliding ribs 422 and the inner layer 2, preventing the sub-sliding ribs 422 from falling off during sliding. Preferably, the sub-sliding ribs 422 and the base 421 are made of the same high-modulus biodegradable material as the outer layer 1, which can ensure the stability of the sliding structure 4. The length of the sub-sliding ribs 422 along the sliding direction is 8mm, and the spacing between adjacent sub-sliding ribs 422 is 6mm, so as to ensure the radial expansion, axial bending and circumferential torsional coupling deformation capability of the inner layer 2, and also to avoid stress concentration that could cause the sliding ribs 42 to break or get stuck.

[0085] When the outer layer 1 of the slide rail 41 is plate-shaped, the slide rail 41 is a rectangular groove with an open top, such as... Figure 4 As shown, when the outer layer 1 is hot-bent into a C-shaped cylindrical form on one side of the slide rail 41, both groove walls of the slide rail 41 are bent and inclined in opposite directions, forming a V-shaped groove slide rail 41 with a small opening and a large bottom. Figure 5 As shown, the cross-sectional shape of the sliding rib 42 matches the V-shaped groove slide rail 41. Its design advantages are twofold: firstly, the resulting V-shaped sliding structure 4 is a classic slide rail 41 structure, requiring lower precision in the fit, which facilitates adaptation to 3D printing molding processes; secondly, this innovative design cleverly combines the transformation of the outer layer 1 from a plate-like shape to a C-shaped cylindrical shape, enabling the rectangular groove of the slide rail 41 to simultaneously transform into a V-shaped groove. This morphological change requires no additional secondary processing, simplifying the manufacturing process and reducing costs. In specific design, it is necessary to accurately calculate whether the inclination angles of the two groove walls of the slide rail 41 after hot bending meet the sliding fit requirements, and the matching sliding rib 42 needs to be set with appropriate tolerance allowances for matching.

[0086] Example 5

[0087] This embodiment, based on Embodiment 4, provides a method for fabricating a three-layer scaffold, including the following steps:

[0088] S1. Pre-printing: Construct three-dimensional models of outer layer 1 and inner layer 2 according to the set structural parameters. The printing material for outer layer 1 is selected as a mixture of polycaprolactone (PCL) and chondrocytes. PCL has the characteristics of high modulus and good biocompatibility. Adding chondrocytes can promote the fusion of the scaffold with tracheal cartilage tissue and improve the biocompatibility and support stability of the scaffold. Fused deposition modeling (FDM) 3D printing of outer layer 1 is used at a printing temperature of 120℃ and a layer thickness of 0.6mm. After printing and cooling, a plate-shaped outer layer 1 is obtained. The printing material for inner layer 2 is selected as a mixture of polydioxanone (PDO) and dexamethasone. PDO has the characteristics of low modulus and good elasticity. Adding anti-inflammatory drugs can further enhance the anti-inflammatory effect of the scaffold and reduce the risk of postoperative infection. Solution extrusion (DIW) 3D printing of inner layer 2 is used. After printing and cooling, a plate-shaped inner layer 2 is obtained. The above-mentioned fused deposition modeling 3D printing equipment and solution extrusion 3D printing equipment can be selected from existing publicly available compatible products and equipment. Specific model parameters are not described here.

[0089] S2. Hot bending and shaping: A 20mm diameter mold with an opening angle of 25° is used. The outer plate-shaped outer layer 1 is heated to 65°C and the inner layer 2 is heated to 55°C using a medical temperature-controlled heating tool. After the material is fully softened, it is bent into shape and enclosed with the mold. The outer layer 1 is bent towards the side with the slide rail 41, and the inner layer 2 is bent towards the opposite side with the slide rib 42. It is cooled at 20~25°C for 20 minutes. After shaping, a C-shaped cylindrical outer layer 1 and inner layer 2 are obtained, while ensuring that there are no defects such as deformation and wrinkles.

[0090] S3. Spinned Repair Layer 3: Electrospinning was used with parameters controlled as follows: voltage 15~25kV, receiving distance 10~15cm, spinning speed 0.9mL / h, and spinning temperature 25~30℃. GelMA hydrogel loaded with vascular endothelial growth factor (VEGF) and endothelial progenitor cells was used as raw material. GelMA (methacrylamide gelatin) has good biocompatibility, biodegradability and film-forming properties. Loading VEGF and endothelial progenitor cells can further promote the regeneration and vascularization of tracheal mucosal epithelial cells and accelerate wound repair. After spinning, a sheet-like repair layer 3 of 0.1~0.3mm was obtained. Then, it was dried at low temperature of 4~8℃ for 1~2h to fix the shape and ensure the morphological stability of repair layer 3.

[0091] S4. Three-layer support preparation: Move the openings of the C-shaped outer layer 1 in opposite directions at a certain angle, so that the V-shaped groove of the slide rail 41 opens to match the sliding edge 42. Then, precisely embed or squeeze the sliding edge 42 of the inner layer 2 into the V-shaped groove slide rail 41. Then, release the outer layer 1 to allow it to elastically return to its original C-shaped shape. Finally, fill the sliding space with biodegradable polyurethane damping elastomer 43. Before filling, a gelatin-chitosan composite quick-setting adhesive can be applied to the surface of the damping elastomer 43 to ensure that the damping elastomer 43 always adheres to the sliding edge. The ends of 42 are bonded together, and the resulting double-layer bracket is assembled. At the same time, the smoothness of the inner layer 2 is tested to ensure that the inner layer 2 can achieve axial reciprocating damped sliding of 4mm along the outer layer 1 without jamming or detachment. Next, a gelatin-chitosan composite quick-curing adhesive with a thickness of 15μm is evenly applied to the inner wall of the inner layer 2 of the double-layer bracket. Then, the sheet-like repair layer 3 is attached to the inner wall of the inner layer 2 and pressed with a pressure of 0.15MPa for 60s to ensure that the repair layer 3 is tightly bonded to the inner layer 2 without defects such as falling off or wrinkling, thus obtaining a three-layer bracket.

[0092] S5. Post-processing and packaging: The three-layer stent is placed in a 35℃ oven for sterile drying for 15 minutes to remove surface moisture and impurities, ensuring the stent is sterile. Then, it is packaged in a sterile environment using medical sterile packaging materials to obtain the packaged finished three-layer stent.

[0093] Example 6

[0094] This embodiment, based on Embodiment 1, provides a method for preparing a double-layer scaffold, including the following steps:

[0095] S1. Use CT medical imaging technology to perform tomographic scanning of the patient's diseased trachea to obtain the diameter and length of the lesion segment. The technical method for obtaining the diameter and length of the lesion segment is not limited here, and other related technical methods can also be used.

[0096] S2. Select the prefabricated plate-shaped outer layer 1 and inner layer 2 of the semi-finished product, and accurately cut the outer layer 1 and inner layer 2 with corresponding length and width dimensions according to the diameter and length dimensions of the lesion segment to obtain the plate-shaped outer layer 1 and inner layer 2 with precise dimensions.

[0097] S3. Select a mold of the corresponding specifications and a medical temperature-controlled heating tool with a suitable softening temperature to fully soften and bend the obtained plate-shaped outer layer 1 and inner layer 2 of precise size, and then cool and shape them to obtain a C-shaped cylindrical outer layer 1 and inner layer 2.

[0098] S4. By using the sliding structure on the outer layer 1 and inner layer 2 in the form of a C-shaped cylinder, the outer layer 1 and inner layer 2 are slidably connected, ensuring that the inner layer 2 can achieve axial reciprocating damped sliding without disengaging from the outer layer 1 along the axial direction, and the sliding length is controlled within the set range, thereby obtaining a double-layer support.

[0099] S5. Perform aseptic post-processing on the obtained double-layer stent, and then apply it directly to clinical use.

[0100] In clinical applications, the method for preparing tracheal stents can also utilize prefabricated plate-shaped semi-finished products of outer layer 1, inner layer 2, and repair layer 3 to simplify the preparation of a three-layer stent. The structural forms of outer layer 1, inner layer 2, and repair layer 3 are not limited, and semi-finished products with different structures, functions, and sizes can be prefabricated to meet different complex clinical needs. Furthermore, the hot bending and sliding connection assembly process is simple and flexible, making it suitable for widespread application.

[0101] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A 3D-printed biodegradable biomimetic gas tube outer support, comprising a high-modulus biodegradable outer layer and a low-modulus biodegradable elastic inner layer, characterized in that, Both the outer and inner layers are 3D printed in one piece in a plate shape. After being hot-bent and enclosed, they are shaped into a C-shaped tube that fits the air pipe wall. The outer layer has several radial through holes, and includes a middle section and extension sections connected to both ends of the middle section along the axial direction. The axial length of the middle section is not less than the axial length of the inner layer. It also includes a biodegradable sliding structure disposed on the inner wall of the intermediate section and the outer wall of the inner layer. The sliding structure enables the axial sliding connection between the outer layer and the inner layer without separation. After surgery, the inner layer can perform axial reciprocating damped sliding and elastic reset relative to the intermediate section along with the tracheal wall, as well as radial and axial expansion and contraction coupling deformation.

2. The 3D-printed biodegradable biomimetic gas tube external support according to claim 1, characterized in that, The sliding structure includes a slide rail, a slide rib, and a damping elastomer; The slide rails are disposed on the inner wall of the middle section, and there are at least three slide rails arranged at circumferential intervals along the middle section. The sliding rib, which slides in conjunction with the slide rail, is disposed on the outer wall of the inner layer. The number and position of the sliding rib correspond to the number and position of the slide rail. After the sliding rib and the slide rail are installed and fitted, a relative sliding space is formed between the two ends of the sliding rib and the extension section. The damping elastomer fills the sliding space to elastically constrain the reciprocating sliding length of the sliding edge, and the damping elastomer is always in contact with the end of the adjacent sliding edge.

3. The 3D-printed biodegradable biomimetic gas tube external support according to claim 2, characterized in that, The sliding edge includes a base extending along the sliding direction of the inner layer and built into the inner layer with a plurality of spaced bases and sub-sliding edges fixedly disposed on the bases. The length of the sub-sliding edges along the sliding direction is 5~10mm, and the spacing between adjacent sub-sliding edges is not less than 4mm.

4. The 3D-printed biodegradable biomimetic gas tube external support according to claim 2, characterized in that, When the outer layer is plate-shaped, the slide rail is a rectangular groove with an open top. When the outer layer is hot-bent into a C-shaped cylindrical shape on one side of the slide rail, the two groove walls of the rectangular groove slide rail are bent and inclined in opposite directions to form a V-shaped groove slide rail with a small opening and a large bottom. The cross-sectional shape of the sliding edge matches the V-shaped groove slide rail.

5. The 3D-printed biodegradable biomimetic gas tube external support according to claim 1, characterized in that, It also includes a repair layer fixed to the inner wall of the inner layer; The repair layer is a composite patch prepared by electrospinning, and the composite patch is loaded with anti-inflammatory factors and epithelial cell regeneration induction factors to cover the tracheal wall wound to achieve early anti-inflammatory effect and continuously induce mucosal epithelial regeneration.

6. The 3D-printed biodegradable biomimetic gas tube external support according to claim 7, characterized in that, The degradation cycles of the repair layer, inner layer, and outer layer increase in a gradient from the inside to the outside.

7. The 3D-printed biodegradable biomimetic gas tube external support according to claim 1, characterized in that, The axial cross-sections of the outer wall of the outer layer and the inner wall of the inner layer are both wavy, and the wavy inner wall and the outer wall together form a hyperboloid structure.

8. The 3D-printed biodegradable biomimetic gas tube external support according to claim 7, characterized in that, The biodegradable material of the tracheal stent is a biodegradable polymer material, including at least two of the following: polyhydroxyalkanoates and their copolymers, polycaprolactone and its copolymers, polyglycolic acid and its copolymers, polybutylene succinate and its copolymers, polyvinyl alcohol and its copolymers, polylactic acid and its copolymers, polylactic acid-glycolic acid copolymers, and polydioxanone and its copolymers.

9. The method for preparing a 3D-printed biodegradable biomimetic gas tube external scaffold according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Pre-printing: Construct a three-dimensional model according to the preset structure and size parameters of the inner and outer layers. Select a mixture of polycaprolactone and chondrocytes as the outer layer printing material and a mixture of polydioxanone and anti-inflammatory drugs as the inner layer printing material. Use fused deposition modeling (FDM) to print the outer layer and solution extrusion modeling (SOA) to print the inner layer. After printing, the outer and inner layers are in the form of plates. S2. Hot bending and shaping: Based on the set support diameter, C-shaped opening size, and material softening temperature requirements, a mold of corresponding specifications and a medical temperature-controlled heating tool with suitable softening temperature are configured to heat and soften the obtained plate-shaped outer and inner layers and bend them to form a shape. After cooling and shaping, a C-shaped cylindrical outer and inner layer is obtained. S3. Fabrication of a double-layer scaffold: The outer and inner layers are slidably connected by sliding structures on the C-shaped outer and inner layers, ensuring that the inner layer can achieve axial reciprocating damped sliding without disengaging from the outer layer along the axial direction, thus obtaining a double-layer scaffold. S4. Spinned repair layer: The sheet-like repair layer is prepared by electrospinning using GelMA hydrogel loaded with vascular endothelial growth factor and endothelial progenitor cells as raw material. The sheet-like repair layer is then dried and shaped at low temperature for later use. S5. Preparation of three-layer scaffold: Apply gelatin-chitosan composite quick-curing adhesive to the inner wall of the inner layer of the double-layer scaffold obtained in step S3, and then attach the sheet-like repair layer accordingly to complete the bonding between the repair layer and the inner layer, thus obtaining a three-layer scaffold. S6. Post-processing and packaging: The double-layer scaffold obtained in step S3 or the triple-layer scaffold obtained in step S5 is aseptically dried and then aseptically packaged to obtain the finished product.

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