A uniform degradation stent based on a bionic function curve and a preparation method thereof

Abstract

The application discloses a uniform degradation blood vessel stent based on a bionic function curve and a preparation method thereof, relates to the technical field of medical devices, and comprises the construction of a blood vessel stent model based on a bionic function curve, selective laser melting additive manufacturing of the blood vessel stent model and surface treatment on a zinc blood vessel stent structure. The zinc blood vessel stent structure can not only realize good mechanical support function, but also still provide strong stability in the material degradation process. The bionic configuration naturally avoids sharp corners of a traditional structure, can guide blood flow to smoothly pass, effectively inhibits the generation of turbulence and vortexes, and in addition, the subsequent degradation behavior of the metal zinc blood vessel stent structure is made more uniform through surface treatment, and local failure does not occur in the degradation process.

Description

A Uniformly Degradable Vascular Stent Based on Bionic Function Curves and Its Fabrication Method Technical Field

[0001] This invention relates to the field of medical device technology, specifically to a uniformly degradable vascular stent based on a biomimetic function curve and its preparation method. Background Technology

[0002] With the accelerating aging of the global population, the incidence of cardiovascular diseases such as atherosclerosis continues to rise, becoming a major threat to human health. Vascular stents represent the forefront of research in interventional medical devices. Stent implantation is a key technology for restoring the patency of narrowed or occluded blood vessels, aiming to provide support by being implanted in blood vessels at specific locations in the body. From non-degradable bare-metal stents to drug-eluting stents, their development has significantly suppressed early restenosis after the procedure. However, the permanently retained metal framework also brings long-term risks such as late-stage in-stent thrombosis, restriction of normal vascular vasomotor function, and impediment to subsequent revascularization.

[0003] Bioresorbable vascular stents, after fulfilling their temporary support function, can safely degrade and be absorbed by tissues in vivo, restoring the blood vessel to its natural state and function. However, during degradation, the supporting force weakens earlier than the vessel wall remodeling is completed, posing a risk of early rebound. Furthermore, whether using traditional laser cutting or emerging additive manufacturing technologies, the support structure design is still largely based on simple geometric patterns, such as rhomboid meshes. This uniform, empirical design makes it difficult to control the smooth mechanical strength during blood pulsation, and the sharp edges at the structural connections significantly disturb blood flow, generating continuous turbulence and eddies. This not only increases the risk of platelet activation and deposition but also hinders rapid endothelial cell coverage. Simultaneously, the uneven degradation behavior of biodegradable materials can lead to localized stent failure, causing the blood vessel to be punctured by sharp points or resulting in vascular narrowing due to insufficient support.

[0004] Against this backdrop, leveraging the technological advantages of additive manufacturing to draw inspiration from nature and conduct biomimetic design has become a cutting-edge direction in vascular stent research and development. Natural biological systems, through millions of years of evolution and optimization, often exhibit outstanding performance in terms of lightweight, high strength, fatigue resistance, and functional adaptability in their structures, such as bones, plant stems, and spider webs. Therefore, there is an urgent need in this field for a vascular stent structure based on biomimetic principles that fully utilizes the advantages of additive manufacturing, achieving synergistic improvements in providing excellent radial support, matching dynamic vascular deformation, promoting rapid endothelialization, maintaining long-term patency, and uniform degradation. Summary of the Invention

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a uniformly degradable vascular stent based on a biomimetic function curve, comprising the following steps:

[0006] Step 1: Construct a vascular stent model based on biomimetic function curves;

[0007] Step 2: Selective laser melting additive manufacturing is performed on the vascular stent model from Step 1 to obtain a zinc vascular stent structure.

[0008] Step 3: Perform surface treatment on the zinc vascular stent structure.

[0009] As a preferred embodiment, the specific method for constructing the vascular stent model in step 1 is as follows:

[0010] First, based on the front reference plane, one or more biomimetic function curves are drawn using the equation-driven curve function. Starting from the origin of the coordinate system, when scanning along the positive X-axis in the equation-driven curve, the point on the curve corresponding to the first local maximum point is set as point A. The first local minimum point that appears immediately after point A in the X-axis direction, and whose Y-coordinate is less than that of point A, is set as point B. Based on the curve contour, a surface stretching operation is performed to generate a continuous and smooth surface with a stretching length of L. Then, a thickening command is executed with a thickness of T to form a waveform thin-walled solid.

[0011] Next, use the bending command to perform three-dimensional spatial modeling on the corrugated thin-walled solid, with bending angles ranging from -220° to -200°. Using point A as a reference, construct reference plane one parallel to the front reference plane, and perform the solid extrusion cut command based on reference plane one to cut off the structure at both ends of the bent corrugated thin-walled solid. Then, perform solid mirroring operation with reference plane one as the plane of symmetry to construct a closed ring solid.

[0012] Using point B as a reference, construct reference plane two parallel to the upper reference plane, and perform a solid stretching and cutting command based on reference plane two to preserve the structure of the closed ring solid on the side where point A is located. Then, perform solid mirroring operation with reference plane two as the plane of symmetry to construct the biomimetic equation vascular stent monomer BEVS-1 with dimensions a1×b1×c1.

[0013] Finally, with the top-view reference plane as a reference, a linear array operation was performed on the biomimetic equation vascular stent BEVS-1 along the direction perpendicular to the top-view reference plane, with an array spacing of c1, to finally construct the biomimetic equation vascular stent BEVS-2, i.e., the vascular stent model.

[0014] Preferred biomimetic function curves include:

[0015] A function curve that mimics the spiral growth pattern of ivy or grapevines and the spiral direction of arteries themselves. , , ,in The helix radius represents the bending radius of the vascular stent model, which depends on the actual needs of the blood vessel. For angle parameters, 0≤ ≤4π, The axial variation rate of the pitch. The radial variation rate of the pitch. For the helical density coefficient 0.1≤ ≤0.5;

[0016] The function curves, mimicking coral skeletons or plant root systems, are based on a torus as the fundamental surface, with height perturbations based on fractal noise functions applied to its surface. ,in For standard torus points, For the disturbance amplitude, 0 ≤ ≤0.1, to avoid thrombosis. For the perturbation frequency, 3≤ ≤12, controlling microstructure density, and These are the coordinates of a point on the standard torus.

[0017] The function curves, mimicking the skeleton of radiolarians or the capsid of viruses, are expressed using polar coordinate equations. , Based on the radius, For modulation depth, These are coefficients used to adjust the overall symmetry.

[0018] The function curves, mimicking the vortex blood flow channels at the aortic root and the spiral structure inside a conch shell, were used to modify the cylindrical parametric equations. , , ,in The inner radius of the stent depends on the actual needs of the blood vessel. and These are the axial and circumferential angle parameters, respectively, 0≤ ≤2π, The distortion factor is 0.1≤ ≤0.8;

[0019] The function curves simulating the undulating surface of intestinal villi were generated using explicit equations. ,in, , The radial coefficient controls the sparsity of the two sine curves. , For wavelength, Phase difference;

[0020] The function curve mimicking the DNA double helix and snake movement is based on a gradually varying frequency helical curve, but with its radius also exhibiting periodic changes. , ,in, The average helix radius depends on vascular demand. To modulate the amplitude, 0.1 ≤ ≤0.4mm, For the frequency of radius change, 1 ≤ ≤6;

[0021] The sine-cosine superposition function curve uses an equation-driven curve function to simultaneously plot two equation curves. The sine curve is... The cosine curve is ,in, The main amplitude, 0.2≤ ≤0.8mm, For secondary amplitude, 0.05 ≤ ≤0.3mm, Main frequency, 1≤ ≤5rad / mm, For the second frequency, 5≤ ≤15rad / mm, For phase difference, 0 ≤ ≤2π.

[0022] Preferably, L ranges from 0.2 to 0.8 mm, and T ranges from 0.2 to 0.8 mm.

[0023] As a preferred option, the laser processing parameters selected in step 2 are as follows:

[0024] The laser scanning power is 80W, the scanning spacing is 40μm, the scanning speed is 600mm / s, the layer thickness is 30μm, and argon gas is used for atmosphere protection throughout the processing.

[0025] Preferably, step 3 specifically includes the following steps:

[0026] Step 3.1: Prepare the surface treatment solution by uniformly mixing nitric acid (1-8 mol / L), hydrochloric acid (4-8 mol / L), and deionized water, wherein the volume ratio of nitric acid, hydrochloric acid, and deionized water is 20-60:20-40:60-0, and the total volume ratio is 100. Place the prepared surface treatment solution in a beaker and place the beaker in a magnetically stirred water bath, setting the temperature to a constant 20°C.

[0027] Step 3.2: Hold the zinc vascular stent structure obtained in step 2 with tweezers and immerse it in the surface treatment solution. Set the rotation speed of the magnetic stirring rotor to 100-300 r / min. Start timing from the moment the zinc vascular stent structure is immersed in the surface treatment solution. The immersion time is 30s-2min.

[0028] Step 3.3: Remove the zinc vascular stent structure and place it in anhydrous ethanol for ultrasonic cleaning for 5-30 minutes. After cleaning, dry it to complete the surface treatment.

[0029] The present invention also provides a uniformly degradable vascular stent based on a biomimetic function curve, which is prepared by the method described above.

[0030] The present invention has the following beneficial effects:

[0031] This scheme utilizes biomimetic function curves to construct a main supporting spiral and auxiliary connecting spirals, followed by spatial interweaving, bending, and arraying to form a complete cylindrical zinc vascular stent structure. This zinc vascular stent structure not only provides excellent mechanical support but also maintains strong stability during material degradation. The biomimetic configuration naturally avoids the sharp corners of traditional structures, guiding blood flow smoothly and effectively suppressing turbulence and eddies. Simultaneously, a chemical solution is used for surface treatment, making the surface smooth to avoid irritating blood vessels and regulating the degradation behavior of the biodegradable material, ensuring more uniform degradation and preventing localized failure during the degradation process. Attached Figure Description

[0032] Figure 1 is a schematic flowchart of the method for preparing a uniformly degradable vascular stent based on a biomimetic function curve in this invention.

[0033] Figure 2 is a schematic diagram of the design process of the vascular stent model in this invention;

[0034] Figure 3 shows the surface microscopic electron microscopy observations of the zinc vascular stent structure before and after surface treatment in this invention; where (a) is the surface morphology of the zinc vascular stent structure after additive manufacturing, and (b) is the surface morphology of the zinc vascular stent structure after surface treatment.

[0035] Figure 4 shows the electron microscopic observations of the zinc vascular stent structures before and after surface treatment in the present invention after immersion in simulated body fluid for 28 days; where (c) is the degradation morphology after additive manufacturing and (d) is the degradation morphology after surface treatment. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0038] Example 1: Referring to Figure 1, a method for preparing a uniformly degradable vascular stent based on a biomimetic function curve includes the following steps:

[0039] Step 1: Construct a vascular stent model based on biomimetic function curves;

[0040] Step 2: Selective laser melting additive manufacturing is performed on the vascular stent model from Step 1 to obtain a zinc vascular stent structure.

[0041] Step 3: Perform surface treatment on the zinc vascular stent structure.

[0042] The specific construction method of the vascular stent model in step 1 is as follows:

[0043] First, based on the front reference plane, one or more biomimetic function curves are drawn using the equation-driven curve function. Starting from the origin of the coordinate system, when scanning along the positive X-axis in the equation-driven curve, the point on the curve corresponding to the first local maximum point (i.e., the peak) is set as point A. The first local minimum point (i.e., the trough) that appears immediately after point A in the X-axis direction, and whose Y-coordinate is less than that of point A, is set as point B. This point selection rule is applicable to different biomimetic function curves. Based on the curve contour, a surface stretching operation is performed to generate a continuous and smooth surface with a stretching length of L. Then, a thickening command is executed with a thickness of T to form a waveform thin-walled solid.

[0044] Next, use the bend command to perform three-dimensional spatial modeling on the corrugated thin-walled solid, with a bending angle of -220° to -200°. Using point A as a reference, construct reference plane one parallel to the front view reference plane (construct reference plane one parallel to the front view reference plane through point A). Then, use the solid extrusion cut command based on reference plane one to cut off the structure at both ends of the bent corrugated thin-walled solid. Finally, use reference plane one as the plane of symmetry to perform a solid mirroring operation to construct a closed ring solid.

[0045] Using point B as a reference, construct reference plane two parallel to the upper reference plane (construct reference plane two parallel to the upper reference plane through point B), and perform a solid stretching and cutting command based on reference plane two to preserve the structure of the closed ring solid on the side where point A is located. Then, perform a solid mirroring operation with reference plane two as the plane of symmetry to construct the biomimetic equation vascular stent monomer BEVS-1 with dimensions a1×b1×c1.

[0046] Finally, with the top-view reference plane as a reference, a linear array operation was performed on the biomimetic equation vascular stent BEVS-1 along the direction perpendicular to the top-view reference plane, with an array spacing of c1, to finally construct the biomimetic equation vascular stent BEVS-2, i.e., the vascular stent model.

[0047] Among them, biomimetic function curves include the following seven types:

[0048] (i) The function curve mimics the spiral growth pattern of ivy or grapevines and the spiral direction of arteries themselves, imitating the spiral growth pattern of ivy or grapevines and the anatomical characteristics of arteries themselves being spiral-oriented. , , ,in The helix radius represents the bending radius of the vascular stent model, which depends on the actual needs of the blood vessel. For the angle parameter, 0 ≤ t ≤ 4π. The axial variation rate of the pitch. The radial variation rate of the pitch. The spiral density coefficient (0.1≤ ≤0.5); Controllable helical main pitch and Together, they control the frequency and amplitude of the wave-like undulations superimposed upon it. By adjusting... The radial support range of the zinc vascular stent structure can be controlled; adjustment The density of the spirals can be altered, thereby regulating the flexibility and support uniformity of the zinc vascular stent structure; adjusting and Periodically varying curvature can be introduced to simulate the torsion of natural blood vessels, further optimizing hemodynamics.

[0049] (ii) The function curves mimicking the coral skeleton or plant root system imitate the complex fractal branching structure of the coral skeleton or plant root system to provide a huge specific surface area, promote cell adhesion and tissue integration, and apply a high degree of perturbation based on the fractal noise function to the surface of the circular torus as the base surface. ,in For standard torus points, For the disturbance amplitude, 0 ≤ ≤0.1, to avoid thrombosis. For the disturbance frequency (3≤ ≤12), controlling microstructure density, and The coordinates of a point on the standard torus; by adjusting It can control surface roughness and pore depth, affecting the endothelial cell adhesion ability and regulating... The density and scale of micropore distribution can be controlled to achieve a multi-level structure from macro to micro, optimizing mechanical interlocking and nutrient penetration.

[0050] (iii) The function curves mimicking the radiolarian skeleton or viral capsid mimic the five-fold symmetry and quasi-crystalline structure present in the radiolarian skeleton or viral capsid. Such structures have extremely high stability and filling efficiency in nature. Polar coordinate equations are used. , The quasi-crystalline symmetry orders are 5, 8, and 10, etc. Based on the radius, To modulate the depth and control the unevenness of the vascular stent after its formation, It is also a coefficient, which can adjust the overall symmetry to a certain extent; by choosing different symmetry orders... Structures with different anisotropic mechanical properties can be designed to match the deformation requirements of blood vessels in different directions. It controls the degree of undulation in the zinc vascular stent structure, affecting its resistance to rupture.

[0051] (iv) The function curves mimicking the vortex blood flow channels at the aortic root and the internal spiral structure of a conch shell are designed to guide laminar flow and eliminate dead flow zones during blood flow. The cylindrical parametric equations are modified as follows: , , ,in The inner radius of the stent depends on the actual needs of the blood vessel. and Here are the parameters, axial and circumferential angle parameters, respectively, 0 ≤ ≤2π, The distortion factor is 0.1≤ ≤0.8; Adjustment It can change the degree of distortion of the zinc vascular stent structure, thereby optimizing the shear stress distribution of the internal flow field, minimizing turbulent energy loss, and achieving excellent antithrombotic performance.

[0052] (v) The function curve of the undulating surface of intestinal villi is simulated to increase the surface area and promote substance exchange and cell attachment. Explicit equations are used to write the equations. ,in, , The radial coefficient controls the sparsity of the two sine curves. , For wavelength (0.5≤ ≤2mm, 0.5≤ ≤2mm), The phase difference is achieved by superimposing multiple sine waves of different frequencies and phases to form a complex periodic profile, which is then adjusted... , (Amplitude) and , (Wavelength) allows for the design of surface morphologies with multi-scale fluctuations, which can both interfere with the laminar flow trajectory of platelets and provide cells with diverse anchoring points.

[0053] (vi) Inspired by the function curves of DNA double helix and snake movement, combining the stability of DNA double helix with the flexibility of snake movement, the radius of the helix is ​​made to change periodically based on the gradually varying frequency helix curve. , ,in, The average helix radius depends on vascular demand. To modulate the amplitude, 0.1 ≤ ≤0.4mm, For the frequency of radius change, 1 ≤ ≤6; parameters and By controlling the amplitude and frequency of radial fluctuations, this design can better adapt to vascular pulsation without increasing material usage, by significantly improving the axial compressibility and resilience of the zinc vascular stent structure.

[0054] (vii) Sine-Cosine Superposition Function Curve: This function uses equation-driven curve plotting to simultaneously draw two equation curves. The sine curve is... The cosine curve is ,in, The main amplitude is 0.2–0.8 mm. The amplitude is secondary (0.05–0.3 mm). Main frequency (1-5 rad / mm). This is the secondary frequency (5-15 rad / mm). The phase difference is (0 to 2π).

[0055] Zinc vascular stent structures are constructed using parametric modeling methods. The core of this method is to generate spatial curves or surfaces using different mathematical equations, and then form the final vascular stent model through a series of feature operations (such as stretching, bending, and arraying). The modeling process has high flexibility and adjustability, and the macroscopic morphology and micromechanical properties of the stent can be precisely controlled by modifying the equation parameters.

[0056] The laser processing parameters selected in step 2 are as follows (pure zinc powder material prepared by gas atomization method is used):

[0057] The laser scanning power is 80W, the scanning spacing is 40μm, the scanning speed is 600mm / s, the layer thickness is 30μm, and argon gas is used for atmosphere protection throughout the processing.

[0058] Step 3 specifically includes the following steps:

[0059] Step 3.1: Prepare the surface treatment solution by uniformly mixing nitric acid (1-8 mol / L), hydrochloric acid (4-8 mol / L), and deionized water, wherein the volume ratio of nitric acid, hydrochloric acid, and deionized water is 20-60:20-40:60-0 (the sum of the volume ratios of the three substances is 100). Place the prepared surface treatment solution in a beaker and place the beaker in a magnetically stirred water bath, setting the temperature to a constant 20°C.

[0060] Step 3.2: Hold the zinc vascular stent structure obtained in step 2 with tweezers and immerse it in the surface treatment solution. Set the rotation speed of the magnetic stirring rotor to 100-300 r / min. Start timing from the moment the zinc vascular stent structure is immersed in the surface treatment solution. The immersion time is 30s-2min.

[0061] Step 3.3: Remove the zinc vascular stent structure and place it in anhydrous ethanol for ultrasonic cleaning for 5-30 minutes. After cleaning, dry it to complete the surface treatment.

[0062] Example 2: This example uses the biomimetic function curve-based uniform degradation vascular stent fabrication method described in Example 1 to prepare a zinc vascular stent structure. The specific construction method of the vascular stent model based on the biomimetic function curve in step 1 is as follows:

[0063] Referring to Figure 2, the sine-cosine superposition function curve is selected as the basic equation. Based on the foresight reference plane, the equation-driven curve function is used to simultaneously plot two equation curves:

[0064] The sine curve is ;

[0065] The cosine curve is ;

[0066] Among them, the principal amplitude =0.5mm, secondary amplitude =0.2mm, main frequency =1, frequency =6, phase difference =0.

[0067] The superposition of these two curves forms a composite waveform surface with complex periodic characteristics. Starting from the origin of the coordinate system, when scanning along the positive X-axis in the equation-driven curve, the point on the curve corresponding to the first local maximum point (i.e., the peak) is set as point A. The first local minimum point (i.e., the trough) that appears immediately after point A in the X-axis direction, and whose Y-coordinate is less than that of point A, is set as point B. Based on the contours of the two curves, a surface stretching operation is performed to generate a continuous and smooth surface solid with a stretching length L of 0.5 mm. Then, a thickening command is executed with a thickness T of 0.5 mm to form a waveform thin-walled solid.

[0068] Next, the bend command is used to perform 3D modeling on the corrugated thin-walled solid. The bending triple axis (x, y, z) is defined as (-1.22, 10.03, 0.5), and the rotation angles (Rx, Ry, Rz) of each coordinate axis are defined as (270, 89.84, 180), with a bending angle of -214°. Using point A as a reference, a reference plane 1 is constructed parallel to the front-view reference plane. Based on the reference plane 1, a solid extrusion cut command is performed to remove the structure at both ends of the bent corrugated thin-walled solid to precisely trim the structural ends. Then, a solid mirroring operation is performed using the reference plane 1 as a plane of symmetry to construct a closed ring solid. This step transforms the open corrugated curve into a tubular structure with a continuous inner surface, eliminating the end effects that may generate turbulence.

[0069] Then, using point B as a reference, a second reference plane is constructed parallel to the upward reference plane. Based on the second reference plane, a solid stretching and cutting command is performed (to define the axial length of the biomimetic equation vascular stent monomer BEVS-1), preserving the structure of the closed circular solid on the side where point A is located. Then, using the second reference plane as the plane of symmetry, a solid mirroring operation is performed to construct the biomimetic equation vascular stent monomer BEVS-1 with dimensions a1×b1×c1. This monomer completely preserves all the geometric features of the sine-cosine composite waveform.

[0070] Finally, with the top-view reference plane as a reference, the biomimetic equation vascular stent BEVS-1 is linearly arrayed along the direction perpendicular to the top-view reference plane with an array spacing of c1, thus constructing a complete biomimetic equation vascular stent BEVS-2 that can be used clinically, i.e., a vascular stent model.

[0071] The parameters of the selected sine-cosine superposition function have clear biological and mechanical regulatory effects:

[0072] Adjusting the principal amplitude It can significantly change the amplitude of the zinc vascular stent structure, thereby regulating the stiffness of its radial support and the contact area of ​​the blood vessel.

[0073] Adjusting frequency and It can change the density of the waveform, which directly affects the flexibility of the zinc vascular stent structure and the number of support points per unit length.

[0074] Adjusting the phase difference It can change the interference mode of the superimposed two waveforms, thereby finely adjusting the microscopic undulations of the waveform surface and optimizing the disturbance of blood flow and the interaction between the zinc vascular stent structure and the vascular wall.

[0075] The final number of linear arrays in the axial direction of the BEVS-2 biomimetic vascular stent depends on the length of the target lesion vessel. Generally, the total axial length should fully cover the lesion segment with slight redundancy, and the number of arrays is usually not less than 3. This is achieved by adjusting the function parameters ( , , , , The parameters (L, T) and manufacturing parameters can be used to precisely control the mechanical behavior and hemodynamic characteristics of zinc vascular stent structures from macroscopic morphology to microscopic performance, thereby achieving personalized matching with the blood vessels of specific patients.

[0076] After the vascular stent model is designed, it is then fabricated using selective laser melting powder bed processing to obtain the zinc vascular stent structure. The zinc vascular stent structure then undergoes surface treatment, the specific steps of which are as follows:

[0077] To prepare the surface treatment solution, mix 4 mol / L nitric acid, 6 mol / L hydrochloric acid, and deionized water evenly, with a volume ratio of 40:20:40. Place the prepared surface treatment solution in a beaker and then place the beaker in a magnetically stirred water bath, setting the temperature to a constant 20°C.

[0078] The zinc vascular stent structure obtained in step 2 was held with tweezers and immersed in the surface treatment solution. The rotation speed of the magnetic stirring rotor was set to 300 r / min. The immersion time was 1 min, starting from the moment the zinc vascular stent structure was immersed in the surface treatment solution.

[0079] The zinc vascular stent structure was removed and placed in anhydrous ethanol for ultrasonic cleaning for 15 minutes. After cleaning, it was dried to complete the surface treatment.

[0080] It should be noted that the formulation of the surface treatment solution depends on the surface area and precision of the workpiece being processed. Generally, hydrochloric acid accounts for no more than 40% of the total solution volume. By adjusting the ratio of nitric acid to hydrochloric acid in the solution, the overall smoothness of the surface and the processing precision of the support can be adjusted.

[0081] As shown in Figure 3, there are significant differences in the surface morphology of the zinc vascular stent structure before and after surface treatment. (a) shows the surface morphology of the zinc vascular stent structure before surface treatment (i.e., after additive manufacturing), and (b) shows the surface morphology of the zinc vascular stent structure after surface treatment. Degradation tests, as shown in Figure 4, show the degradation morphology before surface treatment (i.e., after additive manufacturing) and (d) shows the degradation morphology after surface treatment. Before and after the degradation tests, the degradation performance of different surfaces differed significantly. Before surface treatment, the degraded material was mostly concentrated in one area, while after surface treatment, the degradation pits were smaller and more dispersed, showing a better improvement in uniformity.

[0082] In summary, the zinc vascular stent structure of this invention not only provides excellent mechanical support but also maintains strong stability during material degradation. Its biomimetic configuration naturally avoids the sharp corners of traditional structures, guiding blood flow smoothly and effectively suppressing turbulence and eddies. Furthermore, surface treatment makes the subsequent degradation behavior of the zinc vascular stent structure more uniform, preventing localized failure during degradation.

[0083] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a uniformly degradable vascular stent based on a biomimetic function curve, characterized in that, The process includes the following steps: Step 1, constructing a vascular stent model based on biomimetic function curves; Step 2, performing selective laser melting additive manufacturing on the vascular stent model from Step 1 to obtain a zinc vascular stent structure; Step 3, performing surface treatment on the zinc vascular stent structure; The specific construction method of the vascular stent model in Step 1 is as follows: First, based on the front-view reference plane, one or more biomimetic function curves are drawn using the equation-driven curve function. Taking the origin of the coordinate system as the starting point, when scanning along the positive X-axis in the equation-driven curve, the point on the curve corresponding to the first local maximum point is set as point A. The first local minimum point that appears immediately after point A in the X-axis direction, and whose Y-coordinate is less than that of point A, is set as point B. Based on the curve contour, a surface stretching operation is performed to generate a continuous and smooth surface with a stretching length of L. Then, a thickening command is executed with a thickness of T to form a waveform thin-walled solid; then, a bending command is used to bend the waveform. The thin-walled solid is modeled in three dimensions with a bending angle ranging from -220° to -200°. Using point A as a reference, a reference plane one is constructed parallel to the front-view reference plane. A solid stretching and cutting command is then performed on reference plane one to remove the structures at both ends of the bent, wavy thin-walled solid. Next, a solid mirroring operation is performed using reference plane one as a plane of symmetry to construct a closed ring solid. Then, using point B as a reference, a reference plane two is constructed parallel to the upper-view reference plane. A solid stretching and cutting command is then performed on reference plane two, retaining the structure of the closed ring solid on the side where point A is located. Again, a solid mirroring operation is performed using reference plane two as a plane of symmetry to construct the biomimetic equation vascular stent unit BEVS-1 with dimensions a1×b1×c1. Finally, using the upper-view reference plane as a reference, a linear array operation is performed on the biomimetic equation vascular stent unit BEVS-1 along a direction perpendicular to the upper-view reference plane, with an array spacing of c1, ultimately constructing the biomimetic equation vascular stent BEVS-2, i.e., the vascular stent model.

2. The method for preparing a uniformly degradable vascular stent based on a biomimetic function curve according to claim 1, characterized in that, Bionic function curves include: function curves that mimic the spiral growth pattern of ivy or grapevines, as well as the spiral direction of arteries themselves. ， ， ,in The helix radius represents the bending radius of the vascular stent model, which depends on the actual needs of the blood vessel. For angle parameters, 0≤ ≤4π， The axial variation rate of the pitch. The radial variation rate of the pitch. For the helical density coefficient 0.1≤ ≤0.5; Function curves mimicking coral skeletons or plant root systems, with a torus as the base surface, and height perturbations based on fractal noise functions applied to its surface. ,in For standard torus points, For the disturbance amplitude, 0 ≤ ≤0.1, to avoid thrombosis. For the perturbation frequency, 3≤ ≤12, controlling microstructure density, and The coordinates of points on the standard torus; the function curves mimicking the radiolarian skeleton or viral capsid, using polar coordinate equations. ， Based on the radius, For modulation depth, The coefficients are used to adjust the overall symmetry; the cylindrical parametric equations are modified to resemble the function curves of the vortex blood flow channel at the aortic root and the spiral structure inside a conch shell. ， ， ,in The inner radius of the stent depends on the actual needs of the blood vessel. and These are the axial and circumferential angle parameters, respectively, 0≤ ≤2π， The distortion factor is 0.1≤ ≤0.8; The function curve simulating the undulating surface of intestinal villi was written using explicit equations. ,in, 、 The radial coefficient controls the sparsity of the two sine curves. 、 For wavelength, To represent the phase difference; mimicking the function curves of the DNA double helix and snake movement, based on a gradually varying frequency helical curve, its radius is also made to change periodically. ， ,in, The average helix radius depends on vascular demand. To modulate the amplitude, 0.1 ≤ ≤0.4mm, Let be the frequency of radius change, 1≤ ≤6; Sine-cosine superposition function curve, using the equation-driven curve function to simultaneously plot two equation curves, the sine curve is... The cosine curve is ,in, The main amplitude, 0.2≤ ≤0.8mm, For secondary amplitude, 0.05 ≤ ≤0.3mm, Main frequency, 1≤ ≤5rad / mm, For the second frequency, 5≤ ≤15rad / mm, For phase difference, 0 ≤ ≤2π。 3. The method for preparing a uniformly degradable vascular stent based on a biomimetic function curve according to claim 2, characterized in that, The range of L is 0.2 to 0.8 mm, and the range of T is 0.2 to 0.8 mm.

4. The method for preparing a uniformly degradable vascular stent based on a biomimetic function curve according to claim 3, characterized in that, The laser processing parameters selected in step 2 are as follows: laser scanning power is 80W, scanning spacing is 40μm, scanning speed is 600mm / s, layer thickness is 30μm, and argon gas is used for atmosphere protection throughout the processing.

5. The method for preparing a uniformly degradable vascular stent based on a biomimetic function curve according to claim 4, characterized in that, Step 3 specifically includes the following steps: Step 3.1, prepare the surface treatment solution by uniformly mixing nitric acid (1-8 mol / L), hydrochloric acid (4-8 mol / L), and deionized water, wherein the volume ratio of nitric acid, hydrochloric acid, and deionized water is 20-60:20-40:60-0, and the total volume ratio is 100. Place the prepared surface treatment solution in a beaker and place the beaker in a magnetically stirred water bath, setting the temperature to a constant 20℃; Step 3.2, hold the zinc vascular stent structure obtained in Step 2 with tweezers and immerse it in the surface treatment solution, setting the rotation speed of the magnetic stirring rotor to 100-300 r / min, and start timing from the moment the zinc vascular stent structure is immersed in the surface treatment solution, with an immersion time of 30s-2min; Step 3.3, remove the zinc vascular stent structure and place it in anhydrous ethanol for ultrasonic cleaning for 5-30min. After cleaning, dry it to complete the surface treatment.

6. A uniformly degradable vascular stent based on a biomimetic function curve, characterized in that, It is prepared by the method described in claim 5.

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