A method for preparing a 3D printed sliding buckle infant bioabsorbable vascular stent

Abstract

The present invention relates to the field of vascular stent preparation, and specifically to a method for preparing a 3D printed sliding buckle infant bioabsorbable vascular stent. Draw a vascular stent model, set the model length, diameter, thickness, and grid shape of the stent main grid structure, and generate a model file; input the model file into computer slicing software, select printing materials, set process parameters in layers, design the printing path, and generate a data file; input the data file into a 3D printer for printing. The present invention significantly improves the radial support force of the vascular stent by optimizing the process parameters and steps, meets the requirements of clinical use, and provides a new way to treat vascular stenosis diseases related to congenital heart disease in infants and young children.

Description

Technical Field

[0001] The invention relates to the field of vascular stent preparation, and in particular to a method for preparing a 3D printed sliding buckle infant bioabsorbable vascular stent. Background Art

[0002] Stent implantation is increasingly used in the clinical treatment of vascular stenosis associated with congenital heart disease, such as aortic coarctation, pulmonary artery stenosis, pulmonary atresia combined with ventricular septal defect, and residual vascular obstruction after surgery. Compared with balloon angioplasty, the support provided by stents can effectively prevent arterial elastic recoil, reduce arterial wall damage, and significantly reduce the incidence of postoperative aneurysms and restenosis. Bioresorbable stents have greater advantages than permanent metal stents. After implantation in the body, they gradually degrade and disappear, providing temporary support for narrowed blood vessels, adapting to the growth of blood vessels in children, and avoiding the formation of fixed stenosis. However, there is still a large gap in the research field of bioresorbable stents for vascular stenosis associated with congenital heart disease in infants and young children.

[0003] 3D printing is currently a hot topic in the research of absorbable stent preparation technology. It has the characteristics of fast and low cost, and can tailor-make vascular stents of specific size and complex structure for patients. Among them, the equipment and operation of the molten deposition manufacturing process are simple, and it is suitable for a variety of absorbable polymers, such as polydioxanone, polylactic acid, polycaprolactone, etc., so it is more widely used in the field of vascular stents. Polydioxanone is a degradable aliphatic polyether ester with good mechanical properties and biocompatibility, and a moderate degradation cycle, which is more compatible with the vascular remodeling cycle. Therefore, it is a very potential candidate material for preparing bioabsorbable vascular stents for infants and young children. However, since the modulus and strength of polymer materials are much lower than those of metal stent materials such as stainless steel, cobalt-chromium alloy, etc., the radial support force of polymer stents is inferior to that of metal stents, and it cannot resist the elastic retraction of the vascular wall, causing stenosis or even stent collapse and fracture, thereby limiting its further clinical application. The prior art (CN101972181A) proposes a sliding buckle bioabsorbable stent design. Although this structure improves the radial support force of the stent (higher than the polymer braided structure stent), it is still lower than the commercial metal stent and cannot meet the clinical use requirements. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes a method for preparing a 3D printed sliding buckle infant bioabsorbable vascular stent. The process method adopts the fused deposition manufacturing technology in 3D printing, and by optimizing the process parameters, the radial support force of the sliding buckle infant bioabsorbable vascular stent is significantly improved, providing a new way to treat vascular stenosis related to congenital heart disease in infants.

[0005] The present invention specifically adopts the following technical solutions:

[0006] S1: Draw a sliding buckle infant bioabsorbable vascular stent model in a computer modeling software, set the model length, diameter, thickness, and grid shape of the stent main grid structure, and generate a model file.

[0007] S2: Input the model file into the computer slicing software, select the printing material, set the process parameters in layers, design the printing path, and generate the data file. Process parameters: 1-2 nozzles, nozzle diameter 0.2-0.4mm, nozzle temperature 70-230℃, substrate temperature 20-90℃, printing layer thickness 0.05-0.15mm, printing speed 20-100mm / s, cooling fan status on or off.

[0008] S3: Input the data file into the 3D printer for printing.

[0009] Furthermore, the printing material is at least one of polydioxanone (PPDO), polylactic acid (PLA), and polycaprolactone (PCL).

[0010] Furthermore, the printing process is fused deposition manufacturing.

[0011] Further, the grid shape is printed as a square, rectangle, hexagon, rhombus, triangle or negative Poisson's ratio shape.

[0012] Preferably, the diameter of the stent is 6-10 mm and the thickness of the stent is 0.3 mm.

[0013] Furthermore, the vascular stent is printed in layers. Preferably, the vascular stent is printed in three layers.

[0014] Furthermore, when the printing material is polydioxanone, the process parameters are set as nozzle diameter 0.2 mm, nozzle temperature 150-190° C., substrate temperature 70-90° C., printing layer thickness 0.1 mm, and printing speed 100 mm / s.

[0015] Furthermore, when the printing material is polylactic acid, the process parameters are set as nozzle diameter 0.2 mm, nozzle temperature 190-230°C, substrate temperature 20-60°C, printing layer thickness 0.1 mm, and printing speed 100 mm / s.

[0016] Furthermore, when the printing material is polycaprolactone, the process parameters are set as nozzle diameter 0.2 mm, nozzle temperature 70-130°C, substrate temperature 20-60°C, printing layer thickness 0.1 mm, and printing speed 100 mm / s.

[0017] In a preferred embodiment of the present invention, polydioxanone is selected as the preparation material, the model length is set to 25 mm, the model diameter is 8 mm, the model thickness is 0.3 mm, the grid shape is printed as a square, a single nozzle is used, the nozzle diameter is 0.2 mm, the nozzle temperature is 180°C, the substrate temperature is 90°C, the printing thickness is 0.1 mm, the printing speed is 100 mm / s, and the cooling fan is in the off state.

[0018] In a preferred embodiment of the present invention, polydioxanone is selected as the preparation material, the model length is set to 25 mm, the model diameter is 8 mm, the model thickness is 0.3 mm, the grid shape is printed as a square, a single nozzle is used, the nozzle diameter is 0.2 mm, the nozzle temperature is 190°C, the substrate temperature is 80°C, the printing thickness is 0.1 mm, the printing speed is 100 mm / s, and the cooling fan is in the off state.

[0019] In a preferred embodiment of the present invention, polydioxanone is selected as the preparation material, the model length is set to 25 mm, the model diameter is 8 mm, the model thickness is 0.3 mm, the grid shape is printed as a diamond, a single nozzle is used, the nozzle diameter is 0.2 mm, the nozzle temperature is 180°C, the substrate temperature is 90°C, the printing thickness is 0.1 mm, the printing speed is 100 mm / s, and the cooling fan is in the off state.

[0020] In a preferred embodiment of the present invention, polylactic acid is selected as the preparation material, the model length is set to 25 mm, the model diameter is 8 mm, the model thickness is 0.3 mm, the grid shape is printed as a square, a single nozzle is used, the nozzle diameter is 0.2 mm, the nozzle temperature is 205°C, the substrate temperature is 60°C, the printing thickness is 0.1 mm, the printing speed is 100 mm / s, and the cooling fan is in the on state.

[0021] In a preferred embodiment of the present invention, polylactic acid is selected as the preparation material, the model length is set to 25 mm, the model diameter is 8 mm, the model thickness is 0.3 mm, and it is printed in 3 layers. The grid shape is printed as a square, a single nozzle is used, the nozzle diameter is 0.2 mm, the nozzle temperature is 190°C when printing the bottom layer, the nozzle temperature is 205°C when printing the middle layer, the nozzle temperature is 230°C when printing the top layer, the substrate temperature is 50°C, the printing thickness is 0.1 mm, the printing speed is 100 mm / s, and the cooling fan is on.

[0022] In a preferred embodiment of the present invention, polylactic acid and polycaprolactone are selected as preparation materials, the model length is set to 25 mm, the model diameter is 8 mm, the model thickness is 0.3 mm, and it is printed in 3 layers. The middle layer of the vascular stent is printed with polycaprolactone material, the top and bottom layers are printed with polylactic acid material, the grid shape is printed as a square, two nozzles are used, the diameter of the nozzle is 0.2 mm, the nozzle temperature is 205°C when printing the bottom layer, the nozzle temperature is 80°C when printing the middle layer, the nozzle temperature is 230°C when printing the top layer, the substrate temperature is 30°C, the printing thickness is 0.1 mm, the printing speed is 100 mm / s, and the cooling fan is in the on state.

[0023] In a preferred embodiment of the present invention, polylactic acid and polycaprolactone are selected as preparation materials, the model length is set to 25 mm, the model diameter is 8 mm, the model thickness is 0.3 mm, and it is printed in 3 layers. The middle layer of the vascular stent is printed with polycaprolactone material, the top and bottom layers are printed with polylactic acid material, the grid shape is printed as a square, two nozzles are used, the diameter of the nozzle is 0.2 mm, the nozzle temperature is 190°C when printing the bottom layer, the nozzle temperature is 130°C when printing the middle layer, the nozzle temperature is 210°C when printing the top layer, the substrate temperature is 40°C, the printing thickness is 0.1 mm, the printing speed is 100 mm / s, and the cooling fan is in the on state.

[0024] In a preferred embodiment of the present invention, polydioxanone is selected as the preparation material, the model length is set to 25 mm, the model diameter is 10 mm, the model thickness is 0.3 mm, the grid shape is printed as a square, a single nozzle is used, the nozzle diameter is 0.2 mm, the nozzle temperature is 180°C, the substrate temperature is 80°C, the printing thickness is 0.1 mm, the printing speed is 100 mm / s, and the cooling fan is in the off state.

[0025] The present invention also provides a sliding buckle bioabsorbable vascular stent for infants and young children, which is printed using the above-mentioned preparation method.

[0026] The vascular stent comprises: a stent frame, a stent body, and a tooth structure; before implantation, the stent is in the shape of an unfolded sheet, the head of which is a hollow stent frame, and the tail of which is a stent body and a tooth structure; the size of the stent frame is adapted to the stent body and the tooth structure, allowing the stent tail to penetrate; when the stent tail penetrates the stent frame and is rolled up, the stent frame slides through balloon expansion, passes over the inner teeth and stops at the gap between the two teeth, thereby fastening into a tubular shape; the tooth structure comprises inner teeth and outer teeth, the inner teeth and the outer teeth protrude from the edge of the stent body, and the inner teeth There is a gap between the outer teeth, and they are opposite to each other; the outer teeth are higher than the inner teeth, and the outer contour angles of the inner and outer teeth are rounded, so that the tail of the bracket can easily pass through the bracket frame, and the bracket frame can slide smoothly and not easily damaged; the inner and outer teeth are higher than the inner edge of the bracket frame, so that the bracket frame stops after sliding to the gap between the two teeth, and the bracket is not easy to disengage; the inner and outer teeth have multiple slope shapes, and from the head to the tail of the bracket, the slope angle of the inner teeth is from large to small, and the slope angle of the outer teeth is from small to large.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] Absorbable polymer materials are used as materials for preparing biological vascular stents for infants and young children, which have good mechanical properties, biocompatibility, and bioabsorbability. Optimizing process parameters can improve the crystallinity of absorbable polymer materials and the degree of adhesion between extruded filaments and layers in melt deposition manufacturing, thereby improving the modulus and strength of the material, and then improving the radial support force of the stent. Compared with the overall printing in the prior art, layered printing can print a variety of materials, and different process parameters are set according to the melting point and thermal decomposition temperature of different materials to improve the crystallinity of the material and the degree of adhesion between extruded layers and filaments in melt deposition manufacturing, thereby improving the modulus and strength, and then improving the radial support force of the stent. The radial support force of the sliding buckle infant bioabsorbable vascular stent prepared by this method is higher than that of commercial balloon-expandable metal stents, and can meet the radial force requirements of stents used in clinical practice, providing a new way to treat vascular stenosis diseases related to congenital heart disease in infants and young children.

[0029] Instruction Manual

[0030] Figure 1 This is a flow chart of a method for preparing a 3D printed sliding buckle infant bioabsorbable vascular stent in a specific embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the structure of the sliding buckle bioabsorbable vascular stent for infants and young children printed by the preparation method of the present invention. Specific embodiments

[0032] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are part of the embodiments of the present invention, rather than all the embodiments.

[0033] The purpose of the present invention is to provide a method for preparing a 3D printed sliding buckle infant bioabsorbable vascular stent, and to improve the radial support force of the infant bioabsorbable vascular stent by optimizing the process parameters of fused deposition manufacturing to meet the requirements of clinical use.

[0034] See also Figure 2 The slide buckle infant bioabsorbable vascular stent prepared by the fused deposition manufacturing technology in the 3D printing of the present invention comprises a stent frame 1, a stent body 2, and a tooth structure 3. The head of the stent is a hollow stent frame 1, and the tail is a stent body 2 and a tooth structure 3. The size of the stent frame 1 is adapted to the stent body 2 and the tooth structure 3, and the stent body 2 is a square grid structure. The tooth structure 3 is located on the upper and lower sides of the tail end of the stent body 2, and is composed of inner teeth 4 and outer teeth 5 with multiple inclination angles. The inner teeth 4 and the outer teeth 5 are opposite in direction, and there is a gap between the two teeth, and the gap width is slightly larger than the width of the stent frame 1. From the head to the tail direction of the stent, the slope inclination angle of the inner teeth 4 is from large to small, and the slope inclination angle of the outer teeth 5 is from small to large, and the outer teeth 5 are higher than the inner teeth 4, and both the inner teeth 4 and the outer teeth 5 are higher than the inner edge of the stent frame 1.

[0035] The working principle of the above-mentioned vascular stent is as follows: the stent is in the form of an unfolded sheet before implantation. When in use, the stent body 2 and the tooth structure 3 are inserted into the stent frame 1, rolled up, and placed in a delivery sheath. When implanted in the body and delivered to the diseased blood vessel, as the balloon expands, the stent frame 1 gradually slides along the upper and lower edges of the stent body 2 and passes over the inner teeth 4. After the balloon is removed, the stent frame 1 will not move back or slide further to the tail due to the obstruction of the inner teeth 4 and the outer teeth 5, and the position is fixed in the gap between the inner teeth 4 and the outer teeth 5. The stent is thus tubular and maintains a fixed diameter, providing radial support for the stenotic blood vessel.

[0036] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with a number of embodiments.

[0037] Example 1

[0038] Step 1: Draw a sliding buckle infant bioabsorbable vascular stent model in a computer modeling software, set the model length to 25 mm, diameter to 8 mm, thickness to 0.3 mm, and the grid shape of the stent main body grid structure to a square, and generate a model file.

[0039] Step 2: Input the model file into the computer slicing software, select polydioxanone as the printing material, design the printing path, and generate a data file; at the same time, set the nozzle temperature to 180°C, the substrate temperature to 90°C, the printing thickness to 0.1mm, the printing speed to 100mm / s, and turn off the cooling fan.

[0040] Step 3: Input the data file into the 3D printer for printing. The printer uses a single nozzle with a nozzle diameter of 0.2mm.

[0041] Example 2

[0042] Step 1: Draw a sliding buckle infant bioabsorbable vascular stent model in a computer modeling software, set the model length to 25 mm, diameter to 8 mm, thickness to 0.3 mm, and the grid shape of the stent main body grid structure to a square, and generate a model file.

[0043] Step 2: Input the model file into the computer slicing software, select polydioxanone as the printing material, design the printing path, and generate a data file; at the same time, set the nozzle temperature to 190°C, the substrate temperature to 80°C, the printing thickness to 0.1mm, the printing speed to 100mm / s, and turn off the cooling fan.

[0044] Step 3: Input the data file into the 3D printer for printing. The printer uses a single nozzle with a nozzle diameter of 0.2mm.

[0045] Example 3

[0046] Step 1: Draw a sliding buckle infant bioabsorbable vascular stent model in a computer modeling software, set the model length to 25 mm, diameter to 8 mm, thickness to 0.3 mm, and the grid shape of the stent main grid structure to a diamond, and generate a model file.

[0047] Step 2: Input the model file into the computer slicing software, select polydioxanone as the printing material, design the printing path, and generate a data file; at the same time, set the nozzle temperature to 180°C, the substrate temperature to 80°C, the printing thickness to 0.1mm, the printing speed to 100mm / s, and turn off the cooling fan.

[0048] Step 3: Input the data file into the 3D printer for printing. The printer uses a single nozzle with a nozzle diameter of 0.2mm.

[0049] Example 4

[0050] Step 1: Draw a sliding buckle infant bioabsorbable vascular stent model in a computer modeling software, set the model length to 25 mm, diameter to 8 mm, thickness to 0.3 mm, and the grid shape of the stent main body grid structure to a square, and generate a model file.

[0051] Step 2: Input the model file into the computer slicing software, select polylactic acid as the printing material, design the printing path, and generate a data file; at the same time, set the nozzle temperature to 205°C, the substrate temperature to 60°C, the printing thickness to 0.1mm, the printing speed to 100mm / s, and turn on the cooling fan.

[0052] Step 3: Input the data file into the 3D printer for printing. The printer uses a single nozzle with a nozzle diameter of 0.2mm.

[0053] Example 5

[0054] Step 1: Draw a sliding buckle infant bioabsorbable vascular stent model in a computer modeling software, set the model length to 25 mm, diameter to 8 mm, thickness to 0.3 mm, and the grid shape of the stent main body grid structure to a square, and generate a model file.

[0055] Step 2: Input the model file into the computer slicing software, select polylactic acid as the printing material, print in 3 layers, design the printing path, and generate a data file; at the same time, set the nozzle temperature to 190°C when printing the bottom layer, the nozzle temperature to 205°C when printing the middle layer, and the nozzle temperature to 230°C when printing the top layer, set the substrate temperature to 60°C, the printing thickness to 0.1mm, the printing speed to 100mm / s, and turn on the cooling fan.

[0056] Step 3: Input the data file into the 3D printer for printing. The printer uses a single nozzle with a nozzle diameter of 0.2mm.

[0057] Example 6

[0058] Step 1: Draw a sliding buckle infant bioabsorbable vascular stent model in a computer modeling software, set the model length to 25 mm, diameter to 8 mm, thickness to 0.3 mm, and the grid shape of the stent main body grid structure to a square, and generate a model file.

[0059] Step 2: Input the model file into the computer slicing software, select polylactic acid and polycaprolactone as the printing materials, divide it into 3 layers, the middle layer is printed with polycaprolactone material, the top and bottom layers are printed with polylactic acid material, design the printing path, and generate the data file; at the same time, set the nozzle temperature to 205°C when printing the bottom layer, 80°C when printing the middle layer, and 230°C when printing the top layer, set the substrate temperature to 30°C, the printing thickness to 0.1mm, the printing speed to 100mm / s, and turn on the cooling fan.

[0060] Step 3: Input the data file into the 3D printer for printing. The printer uses two nozzles to print simultaneously, and the nozzle diameter is 0.2mm.

[0061] Example 7

[0062] Step 1: Draw a sliding buckle infant bioabsorbable vascular stent model in a computer modeling software, set the model length to 25 mm, diameter to 8 mm, thickness to 0.3 mm, and the grid shape of the stent main body grid structure to a square, and generate a model file.

[0063] Step 2: Input the model file into the computer slicing software, select polylactic acid and polycaprolactone as the printing materials, divide it into 3 layers, the middle layer is printed with polycaprolactone material, the top and bottom layers are printed with polylactic acid material, design the printing path, and generate the data file; at the same time, set the nozzle temperature to 190°C when printing the bottom layer, 130°C when printing the middle layer, and 210°C when printing the top layer, set the substrate temperature to 40°C, the printing thickness to 0.1mm, the printing speed to 100mm / s, and turn on the cooling fan.

[0064] Step 3: Input the data file into the 3D printer for printing. The printer uses two nozzles to print simultaneously, and the nozzle diameter is 0.2mm.

[0065] Example 8

[0066] Step 1: Draw a sliding buckle infant bioabsorbable vascular stent model in a computer modeling software, set the model length to 25 mm, diameter to 10 mm, thickness to 0.3 mm, and the grid shape of the stent main body grid structure to a square, and generate a model file.

[0067] Step 2: Input the model file into the computer slicing software, select polydioxanone as the printing material, design the printing path, and generate a data file; at the same time, set the nozzle temperature to 180°C, the substrate temperature to 80°C, the printing thickness to 0.1mm, the printing speed to 100mm / s, and turn off the cooling fan.

[0068] Step 3: Input the data file into the 3D printer for printing. The printer uses a single nozzle with a nozzle diameter of 0.2mm.

[0069] A radial compression test was performed on the sliding buckle infant bioabsorbable vascular stent provided in the embodiment. The stent in the buckled state after balloon expansion was placed inside the fixture of the rolling radial loading device (not shown in the figure), which consists of a fan-shaped wedge. The effective diameter of the central opening of the rolling head is changed by the movement of the wedge, thereby compressing the stent. The test temperature is 37±2°C, and the compression rate is 0.05mm / s. The force value when the stent is compressed to 85% of the initial diameter is divided by the initial length of the stent to obtain the radial support force of the stent. As shown in Tables 1 and 2, the radial support force of the sliding buckle infant bioabsorbable vascular stent provided in the embodiment is higher than that of the commercial metal stent currently used in clinical practice, and can meet the requirements of clinical use. Therefore, the sliding buckle bioabsorbable vascular stent has broad application prospects in the field of treating vascular stenosis diseases.

[0070] Table 1 Comparison of radial support force between Examples 1-7 and commercial metal stents

[0071]

[0072] Note: The diameter of the commercial cobalt-based stent and the stainless steel stent in Table 1 is 8 cm

[0073] Table 2 Comparison of radial support force between Example 8 and commercial metal stents

[0074] Example 8 Commercial cobalt-based stents Radial support force (N / mm) 2.784 2.242

[0075] Note: The diameter of the commercial cobalt-based stent in Table 2 is 10 cm

[0076] By comparing Tables 1 and 2, it can be seen that the radial support force of the sliding buckle bioresorbable vascular stent for infants and young children prepared by optimizing process parameters and layered printing is significantly improved, and its mechanical properties are stronger than those of commercial balloon-expandable metal stents, which can meet the radial force requirements of the stent for clinical use.

[0077] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a 3D printed sliding buckle bioabsorbable vascular stent for infants and young children, characterized in that: The following steps are involved: Step 1: Draw a sliding buckle infant bioabsorbable vascular stent model in a computer modeling software, set the model length to 25 mm, diameter to 8 mm, thickness to 0.3 mm, and the grid shape of the stent main grid structure to a square, and generate a model file; Step 2: Input the model file into the computer slicing software, select polylactic acid as the printing material, print in 3 layers, design the printing path, and generate a data file; at the same time, set the nozzle temperature to 190°C when printing the bottom layer, 205°C when printing the middle layer, and 230°C when printing the top layer, set the substrate temperature to 60°C, the printing thickness to 0.1mm, the printing speed to 100mm / s, and turn on the cooling fan; Step 3: Input the data file into the 3D printer for printing. The printer uses a single nozzle with a nozzle diameter of 0.2mm; The absorbable vascular stent comprises a stent frame (1), a stent body (2), and a tooth structure (3); the stent head is a hollow stent frame (1), and the stent body (2) and the tooth structure (3) are formed at the rear end; the stent frame (1) is adapted to the stent body (2) and the tooth structure (3), and the stent body (2) is a square grid structure; the tooth structure (3) is located at the upper and lower sides of the rear end of the stent body (2), and is composed of inner teeth (4) and outer teeth (5) in a slope shape with multiple inclination angles, the inner teeth (4) and the outer teeth (5) are oriented in opposite directions, there is a gap between the two teeth, and the width of the gap is slightly greater than the width of the stent frame (1); from the stent head to the rear end, the slope angle of the inner teeth (4) decreases from large to small, and the slope angle of the outer teeth (5) increases from small to large, the outer teeth (5) are higher than the inner teeth (4), and both the inner teeth (4) and the outer teeth (5) are higher than the inner edge of the stent frame (1).

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