阅读说明：本技术 聚合物全降解血管支架微尺度3d打印制备方法、装置及其应用 (Micro-scale 3D printing preparation method and device for polymer fully-degradable intravascular stent and application of micro-scale 3D printing preparation method and device ) 是由 兰红波 许权 赵佳伟 彭子龙 于 2019-09-25 设计创作，主要内容包括：本发明属于医用聚合物全降解血管支架和微纳3D打印技术领域,具体涉及一种用于聚合物全降解血管支架的微尺度3D打印方法、装置及其应用,利用单电势的电场驱动喷射微尺度3D打印技术,采用生物可降解高分子热塑材料作为打印基体材料,增强相材料和药物粉末为填料,在圆柱面基底上打印出所需要的空心、圆柱、网状聚合物全降解血管支架,可实现精确控制降解速度、力学性能、药物缓释控释的聚合物全降解血管支架的高效和低成本制造。(The invention belongs to the technical field of medical polymer fully-degradable vascular stents and micro-nano 3D printing, and particularly relates to a micro-scale 3D printing method and device for the polymer fully-degradable vascular stent and application thereof.)

1. A microscale 3D printing method for a polymer fully-degradable vascular stent is characterized by comprising the following steps:

step 1: pretreatment of print substrates

The method comprises the following steps of pretreating a substrate, wherein a cylindrical substrate is selected, and the diameter of the cylindrical substrate is determined according to the diameter of a to-be-printed intravascular stent, and the pretreatment of the substrate comprises the following steps: (1) placing the printing substrate in physiological saline for ultrasonic treatment, drying by blowing with nitrogen, then placing in medical alcohol for ultrasonic treatment, and finally drying by blowing with nitrogen; (2) sterilizing the printing substrate, wherein the sterilization is one or more of dry heat, moist heat sterilization, ultraviolet sterilization, microwave sterilization and ozone generator sterilization; (3) and coating a layer of water-soluble material on the surface of the treated printing substrate.

Step 2: guiding the vessel stent printing path program and preparing the printing material

Designing a printing path according to the structural requirements of the blood vessel stent, guiding the blood vessel stent into a printing device, preparing a printing material and loading the printing material into a printing device.

The polymer full-degradable blood vessel stent is designed into an inner-outer layer structure or a multilayer structure, the inner layer structure consists of a base material and a filler, the base material is a biological full-degradable thermoplastic high polymer material, the filler is a reinforcing phase, the base material and the filler are put into a mixing device to be uniformly mixed, the mixed material is put into a storage barrel and is placed into a composite material printing nozzle feeding template for standby; the outer layer structure material consists of a base material and a filler, the base material is a biological full-degradable thermoplastic high polymer material, the filler is medicinal powder, and the base material and the filler are respectively placed in two different feeding devices of the functionally gradient structure printing nozzle module;

and step 3: multi-nozzle microscale 3D printing intravascular stent

Printing an internal structure: the inner layer is of a skeleton structure and provides enough mechanical properties

The process of utilizing the single-potential electric field to drive the injection deposition multi-nozzle 3D printing of the multilayer vascular stent structure comprises the following steps:

3.1: printing initialization, namely moving a composite material printing nozzle module, namely a printing nozzle 1, to a printing original position to enable the composite material printing nozzle module to be positioned above the axis of a substrate, setting the temperature according to the melting point of the printing material, starting a heater to enable the printing material in a printing device to be in a molten state, and setting the temperature and the inner diameter of the heater of the printing nozzle 1 to ensure that the printing material meets the printing requirement at a nozzle;

3.2: starting the backpressure of the storage vat, supplying materials to the printing nozzle 1, starting the backpressure of the high-voltage pulse power supply and the nozzle module, extruding the printing materials to the tip of the nozzle, stretching and deforming to gradually form superfine continuous conical jet flow;

3.3: the combination of the nozzle movement and the substrate rotation realizes the manufacturing of high-precision arbitrary complex grids or patterns on the cylindrical substrate.

3.4: after printing, turning off the high-voltage power supply and the back pressure, turning off each heater, moving the printing nozzle 1 to the original point of the device, and returning the rotary workbench to the initial position;

printing an outer layer structure: the outer layer is a high-density pore drug slow-release structure

3.5: switching a functional gradient structure printing nozzle module, namely a printing nozzle 2, feeding materials to a machine barrel according to a designed proportion through two different feeding devices respectively provided with an outer layer structure base material and a filler according to the designed functional gradient structure, then matching the extrusion and injection speeds of the printing materials with the feeding speeds by adjusting the rotating speed of a screw driving motor, and setting the temperature and the inner diameter of a heater of the printing nozzle 2 according to the melting point of the printing materials to ensure that the temperature of a nozzle accurately meets the printing requirement;

3.6: starting a high-voltage power supply, adjusting the voltage value, so that the outer layer printing material extruded to the tip of the nozzle is stretched and deformed under the comprehensive action of various forces to gradually form superfine cone jet flow;

3.7: the high-precision manufacturing of the grid structure on the rod-shaped substrate is realized by combining the movement of the nozzle of the printing nozzle 2 and the rotation motion of the substrate;

3.8: after the printing of the outer layer structure is finished, the high-voltage power supply and the back pressure are closed, all heaters are closed, the printing nozzle 2 is moved to the original point of the device, and the printing substrate is taken down;

and 4, step 4: intravascular stent post-treatment

And taking the printed blood vessel out of the printing substrate, in order to avoid the damage of the blood vessel stent, integrally placing the printed blood vessel stent and the printing substrate into a solution for stripping, and finally cutting the size of the blood vessel stent.

In the step 1, the water-soluble material is PVA and the like, and the thickness of the coating is about 20-100 μm.

In the step 1, the substrate material is one or more of glass, ceramic, stainless steel, titanium alloy and cobalt-based alloy.

In the step 2, the geometrical shape of the intravascular stent is mainly a hollow, reticular and tubular cylindrical structure.

In the step 2, the functional gradient layer printed by the nozzle module is printed by adopting a functional gradient structure, and the functional gradient layer can be a functional gradient layer with continuously changed components and ratio, or a gradient layer containing multiple layers of components and fixed ratio, or the combination of the two layers; and each layer has a thickness of 0.5-100 μm;

the printing material comprises a base material and a filler, wherein the base material is a crushed block or powder, and the preferred base material is powder with the particle size of 10-500 mu m; the grain diameter of the medicine and the reinforcing phase in the filler is 10nm-10 mu m; the uniformity of the mixed materials of the inner layer structure and the outer layer structure can be effectively improved through the matching of the sizes of the matrix material and the filler, so that the printing stability, the excellent mechanical property and the drug slow-release and controlled-release performance are ensured;

the biodegradable thermoplastic high polymer material is one or more of polylactic acid, levorotatory polylactic acid, polyglycolic acid/polylactic acid copolymer, polycaprolactone, polyglycolic acid and polyhydroxybutyric acid; preferably, the matrix material of the inner layer structure is levorotatory polylactic acid, and the reinforcing phase of the inner layer structure is one or more of nano polymer particles, carbon fibers, a plasticizer, bioceramic and salt particles; the matrix material of the outer layer structure is polycaprolactone wire material, and the filler is various medicines, preferably rapamycin powder.

2. The micro-scale 3D printing method for the polymer fully degradable blood vessel stent according to claim 1, characterized in that: the radial change of the concentration content of the drugs in the polymer fully-degradable intravascular stent is realized by changing the doping proportion of the drugs in real time in the printing process, so that the polymer fully-degradable intravascular stent has different drug slow-release speeds in the degradation process.

3. The microscale 3D printing method for the polymer fully-degradable intravascular stent in claim 1 is technically characterized by adopting a single-potential electric field-driven jet 3D printing technology without using a grounded conductive substrate as a counter electrode. The method can ensure that metal materials such as glass, ceramics, stainless steel, titanium alloy, cobalt-based alloy and the like can be used as printing substrates, and is particularly suitable for conformal printing on curved surfaces and 3D surfaces.

4. The micro-scale 3D printing method for the polymer fully degradable blood vessel stent according to claim 3, characterized in that: by adjusting the technological parameters of the electric field driven microscale 3D printing equipment, the parameters of the line width, the porosity, the diameter and the dimension of the reticular structure of the intravascular stent are accurately regulated and controlled, and the controllable regulation of the mechanical property, the degradation speed and the drug slow-release property is realized. Wherein, the biological polymer full degradation blood vessel stent can be hollow, cylinder, net and the like, and the wire width of the stent can be 0.5 μm to 500 μm. The process parameters comprise power supply voltage, power supply duty ratio, power supply frequency, spray head back pressure, the distance between the needle point and the base material and the rotating speed of the substrate, so that the line width, the geometric shape and the porosity of the manufactured vascular stent are adjusted, the self-focusing effect of 3D printing is driven by an electric field, and the aspect ratio of the lines is changed by multilayer accumulation.

5. A microscale 3D printing device for polymer full-degradable vascular stents, characterized in that: the method comprises the following steps: the device comprises a motion module, a rotary workbench, a composite material printing spray head module, a functional gradient structure printing spray head feeding module, a composite material printing spray head feeding module, a high-voltage power supply module, a back pressure control module and a rack; the motion module is a gantry structure three-axis motion module and comprises an X axis, a Y axis and a Z axis, wherein the three axes are orthogonally arranged on stand columns of the rack, the X axis is vertically arranged on the double Y axes to form a gantry structure, and the Z axis is arranged on the X axis and is vertical to a horizontal plane; the rotary workbench is used for clamping the cylindrical base material to realize deposition molding of the printing material on the surface of the cylinder; the composite material printing spray head module is a fused deposition spray head and is used for printing thermoplastic composite materials and comprises a three-way joint, an annular heater, a connecting pipe heating block, a connecting pipe, a nozzle heating block and a nozzle; the three-way joint is respectively connected with the air pipe, the composite material printing nozzle feeding module and the nozzle 1, the three-way joint is wrapped with an annular heater, the backpressure of the printing nozzle is adjusted through a pressure regulating valve, the nozzle heating block is arranged on the nozzle 1, and the connecting pipe heating block keeps the printing material passing through the connecting pipe in a molten state; the functional gradient structure printing nozzle module is a multi-material active mixing nozzle, realizes feeding-mixing-extruding integrated printing of different printing materials by adopting a screw structure, and comprises a driving motor, a machine barrel, an annular heater, a nozzle heating block, a nozzle 2 and a single screw; the single screw is matched with the driving motor through the coupler and is coaxially arranged on the bracket with the machine barrel, the outer part of the machine barrel is wrapped with the annular heater, the nozzle 2 is arranged on the machine barrel, and the nozzle heating block can realize continuous heating of the nozzle 2; the functional gradient structure printing nozzle feeding module can supply wires, particles, powder and liquid printing materials to the printing nozzle; the composite material printing spray head feeding module adjusts the air pressure through the pressure adjusting valve to provide back pressure for the printing material, so that feeding into the composite material printing spray head is realized; the high-voltage power supply module comprises a high-voltage power supply and a signal generator, and the nozzles of the two printing spray head modules are connected with the positive pole of the high-voltage power supply.

6. The micro-scale 3D printing device for the polymer fully degradable blood vessel stent according to claim 5, wherein: the Y axis is driven by double motors, two Y-axis guide rails are kept parallel, the X, Z axis is driven by a linear motor, and the Y axis is driven by a stepping motor; the axial direction of the rotary worktable is parallel to the motion direction of the X axis; the coaxiality of the mounting hole of the rotary worktable is not less than 3 mu m.

7. The micro-scale 3D printing device for the polymer fully degradable blood vessel stent according to claim 5, wherein: the effective stroke of the X axis is 0-200mm, the positioning precision is not less than +/-2 mu m, the repeated positioning precision is not less than +/-1 mu m, the maximum speed is 100mm/s, and the maximum acceleration is 1000m/s²(ii) a The effective travel of the Z axis is 0-100 μm, the positioning accuracy is not less than +/-2 μm, the repeated positioning accuracy is not less than +/-1 μm, the maximum speed is 50mm/s, and the maximum acceleration is 1000m/s²(ii) a The effective stroke of the Y axis is 0-200mm, the positioning precision is not less than +/-2 mu m, the repeated positioning precision is not less than +/-1 mu m, the maximum speed is 100mm/s, and the maximum acceleration is 1000m/s²(ii) a Preferably, the second printing nozzle adopts a screw structure, the mixing and pressure supply extrusion of printing materials are realized by the screw, and the diameter of the screw is 10-20 mm; preferably, the printing nozzle is a glass needle or a stainless steel nozzle which is treated by a Wuzang needle or a gold spraying conductive treatment, and the inner diameter range of the nozzle1-200μm。

8. Use of a microscale 3D printing device for polymeric fully-degradable vascular stents according to any one of claims 5 to 7 for printing polymeric fully-degradable vascular stents.

Technical Field

The invention belongs to the technical field of medical polymer fully-degradable intravascular stents and micro-nano 3D printing, and particularly relates to a micro-scale 3D printing method and device for the polymer fully-degradable intravascular stents and application thereof.

Background

Cardiovascular disease is the leading killer leading to human death, and statistically, the number of deaths worldwide at 1/3 is from cardiovascular disease. In recent years, a stent-graft, which is an interventional operation for supporting a blood vessel and compressing plaque in the lumen of the blood vessel and preventing rebound of the blood vessel and protrusion of intimal plaque into the blood vessel by implanting a stent into a body, has been developed as one of the most effective methods for treating cardiovascular stenosis rate diseases, and is widely used in the fields of coronary heart disease, cardiovascular disease, cerebrovascular disease, visceral vessel, peripheral vessel, and the like. Vascular stents are mainly classified into four types: balloon stents (first generation), bare metal stents (second generation), Stent graft (third generation), Biodegradable Vascular stents (fourth generation, Biodegradable Vascular Stent, BVS). The fourth generation biodegradable stent can be slowly degraded in the blood vessel of the human body and is completely absorbed by the tissue, and the common biodegradable stent can be completely dissolved after two years, has little influence on the human body and is a currently accepted safer and more effective stent. The polymer full-degradable blood vessel stent is the most studied one of the biodegradable blood vessel stents, relates to the multidisciplinary and multi-field such as clinical medicine, biological subject, manufacturing process and material, and the core technology thereof is always in the monopoly situation abroad, and belongs to the advanced medical technology. An ideal polymer-based biodegradable vascular stent should have the following basic characteristics: (1) is non-toxic and has good biocompatibility; (2) has certain mechanical strength and compliance; (3) the biodegradable and degradable regulator is provided; (4) has three-dimensional porous structure (reasonable geometric characteristics and void structure) to facilitate cell adhesion, growth and proliferation; (5) has better blood compatibility. At present, there are various methods for manufacturing polymer fully degradable vascular stents, such as: various manufacturing techniques such as electrospinning, Fused Deposition Modeling (FDM), laser cutting, thermally induced phase separation, and self-assembly, however, these techniques or solutions all have limitations at present. (1) Electrostatic spinning: the polymer solution or melt is sprayed under the action of a high-voltage electrostatic field to form polymer micro jet flow to prepare the nano fiber for spinning processing. The jet flow of the traditional electrostatic spinning process for manufacturing the vascular stent is disordered and uncontrollable, so that the uniform and controllable manufacturing of the pore structure of the vascular stent is difficult to realize, and meanwhile, the jet flow is a fine wire with the diameter of nanometer, so that the formed structure has the defect of poor mechanical property; (2) fused deposition forming: the method has the advantages that the speed of printing the vascular stent by the FDM process is high, controllable adjustment of parameters such as structures, shapes and porosity of various vascular stents can be realized, the problems that the surface smoothness of the manufactured vascular stent is poor and accurate printing cannot be realized still exist, the accurate extrusion amount of materials is difficult to control in the traditional FDM process, certain influence is exerted on the minimum molding size and the printing accuracy (the diameter is 2-4 mm, the hollow, cylindrical and net-shaped structures) of the vascular stent, meanwhile, the radial support performance is weak, and a large amount of supports are required to be added for printing the complex net-shaped structures and are difficult to remove; (3) laser cutting (engraving): the method generally adopted by the forming intravascular stent is mainly used for processing a metal intravascular stent, and the method also reports that the intravascular stent is manufactured by cutting a polylactic acid material by femtosecond laser, the laser cutting has inevitable problems of heat affected zone, insufficient surface quality and the like, and a subsequent complex treatment process is needed, so that the production cost of the intravascular stent is increased, and the intravascular stent is expensive; (4) the thermally induced phase separation is easy to generate a compact cortex layer and closed holes when the vascular stent is prepared, so that the performance of the vascular stent has uncontrollable adverse effects and the like; (5) self-assembly is a technology that many similar individuals spontaneously combine to form coherent and stable high-level structures without external instructions, basic structural units (molecules, nano materials, substances with micrometer or larger scale) spontaneously form ordered structures, nanofibers (a few nanometers) which are thinner than electrostatic spinning can be realized, the manufacturing precision is higher, but the process complexity is higher, and meanwhile, the more precise manufacturing technology is involved, the cost is high, and the production efficiency is low. Therefore, the existing technologies are difficult to meet the performance requirements of the ideal polymer fully-degradable vascular stent, and especially, matching the degradability and drug slow release (controllable drug release) of the polymer fully-degradable vascular stent faces a greater challenge. The development of a new method for manufacturing a high-performance polymer-based biodegradable intravascular stent which is nontoxic and nonirritating and has good mechanical strength, absorbability, chemical stability, degradability and biocompatibility is urgently needed.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a high-efficiency and low-cost manufacturing method for a polymer fully-degradable intravascular stent, which can accurately control the degradation speed, the mechanical property and the drug slow-release and controlled-release by using a microscale 3D printing method and a device thereof. The method is characterized in that a single-potential electric field-driven jet microscale 3D printing technology is utilized for the first time, a biodegradable high-polymer thermoplastic material is used as a printing base material, a reinforcing phase material and medicine powder are used as fillers, and the required hollow, cylindrical and reticular polymer fully-degradable intravascular stent is printed on a cylindrical surface substrate.

In order to achieve the purpose, the invention adopts the following technical scheme: a microscale 3D printing method for a polymer fully-degradable vascular stent comprises the following steps:

step 1: pretreatment of print substrates

The method comprises the following steps of pretreating a substrate, wherein a cylindrical substrate is selected, and the diameter of the cylindrical substrate is determined according to the diameter of a to-be-printed intravascular stent, and the pretreatment of the substrate comprises the following steps: (1) placing the printing substrate in physiological saline for ultrasonic treatment, drying by blowing with nitrogen, then placing in medical alcohol for ultrasonic treatment, and finally drying by blowing with nitrogen; (2) sterilizing the printed substrate; (3) and coating a layer of water-soluble material on the surface of the treated printing substrate.

Step 2: guiding the vessel stent printing path program and preparing the printing material

Designing a printing path according to the structural requirements of the blood vessel stent, guiding the blood vessel stent into a printing device, preparing a printing material and loading the printing material into a printing device.

The polymer full-degradable intravascular stent is designed into an inner layer structure and an outer layer structure or a multilayer structure, the inner layer structure is composed of a base material and a filler, the base material is a biological full-degradable thermoplastic high polymer material, the filler is mainly a reinforcing phase, the base material and the filler are put into a mixing device to be uniformly mixed, the mixed material is put into a storage barrel and is placed into a composite material printing nozzle feeding module for standby; the outer layer structure material consists of a base material and a filler, the base material is a biological full-degradable thermoplastic high polymer material, the filler is mainly medicine powder, and the base material and the filler are respectively placed in two different feeding devices of the functionally gradient structure printing nozzle module;

and step 3: multi-nozzle microscale 3D printing intravascular stent

Printing an internal structure: the inner layer is of a skeleton structure and provides enough mechanical properties

The process of utilizing the single-potential electric field to drive the injection deposition multi-nozzle 3D printing of the multilayer vascular stent structure comprises the following steps:

3.1: printing initialization, namely moving a composite material printing nozzle module, namely a printing nozzle 1, to a printing original position to enable the composite material printing nozzle module to be positioned above the axis of a substrate, setting the temperature according to the melting point of the printing material, starting a heater to enable the printing material in a printing device to be in a molten state, and setting the temperature and the inner diameter of the heater of the printing nozzle 1 to ensure that the printing material meets the printing requirement at a nozzle;

3.2: starting the backpressure of the storage vat, supplying materials to the printing nozzle 1, starting the backpressure of the high-voltage pulse power supply and the nozzle module, extruding the printing materials to the tip of the nozzle, stretching and deforming to gradually form superfine continuous conical jet flow;

3.3: the combination of the nozzle movement and the substrate rotation realizes the manufacturing of high-precision arbitrary complex grids or patterns on the cylindrical substrate.

3.4: after printing, turning off the high-voltage power supply and the back pressure, turning off each heater, moving the printing nozzle 1 to the original point of the device, and returning the rotary workbench to the initial position;

printing an outer layer structure: the outer layer is a high-density pore drug slow-release structure

3.5: switching a functional gradient structure printing nozzle module, namely a printing nozzle 2, feeding materials to a machine barrel according to a designed proportion through two different feeding devices respectively provided with an outer layer structure base material and a filler according to the designed functional gradient structure, then matching the extrusion and injection speeds of the printing materials with the feeding speeds by adjusting the rotating speed of a screw driving motor, and setting the temperature and the inner diameter of a heater of the printing nozzle 2 according to the melting point of the printing materials to ensure that the temperature of a nozzle accurately meets the printing requirement;

3.6: starting a high-voltage power supply, adjusting the voltage value, so that the outer layer printing material extruded to the tip of the nozzle is stretched and deformed under the comprehensive action of various forces to gradually form superfine cone jet flow;

3.7: the high-precision manufacturing of the grid structure on the rod-shaped substrate is realized by combining the movement of the nozzle of the printing nozzle 2 and the rotation motion of the substrate;

3.8: after the printing of the outer layer structure is finished, the high-voltage power supply and the back pressure are closed, all heaters are closed, the printing nozzle 2 is moved to the original point of the device, and the printing substrate is taken down;

and 4, step 4: intravascular stent post-treatment

And taking the printed blood vessel out of the printing substrate, in order to avoid the damage of the blood vessel stent, integrally placing the printed blood vessel stent and the printing substrate into a solution for stripping, and finally cutting the size of the blood vessel stent.

Further, in the step 1, the substrate material is selected from metal materials such as glass, ceramics, stainless steel, titanium alloy, cobalt-based alloy and the like, and the disinfection and sterilization method adopts one or more of the above.

Further, in the step 1, the water-soluble material is PVA and the like, and the thickness of the coating is about 20-100 μm.

Further, in the step 1, the sterilization manner includes, but is not limited to, heat sterilization (dry heat sterilization, wet heat sterilization), radiation sterilization (ultraviolet sterilization, microwave sterilization, ozone generator sterilization, etc.), and one or more methods thereof are adopted.

Further, in the step 2, the geometrical shape of the vascular stent is mainly a hollow and reticular (tubular) cylindrical structure.

Further, in the step 2, the printing material mainly comprises a base material and a filler, wherein the base material comprises high polymer materials such as polylactic acid, levorotatory polylactic acid, polyglycolic acid/polylactic acid copolymer, polycaprolactone, polyglycolic acid, polyhydroxybutyric acid and the like; the filler comprises various medicaments for accelerating the growth and the repair of tissues and the like, such as rapamycin, everolimus, paclitaxel, chitosan, dex and the like; the reinforcing item is used for improving the mechanical property and the service life of the bracket, such as nano polymer particles, carbon fibers, a plasticizer, biological ceramics, salt particles and the like. By mixing the matrix material and the filler, a composite material having certain functions and mechanical properties can be prepared.

Further, the matrix material may be one or more of the above, and the filler may be one or more of the above.

Further, the base material and the filler in the printing material can be crushed blocks or powder, and the preferred base material is powder with the particle size of 10-500 mu m; the grain diameter of the medicine and the reinforcing phase in the filler is 10nm-10 μm. The uniformity of the mixed materials of the inner layer structure and the outer layer structure can be effectively improved through the matching of the sizes of the matrix material and the filler, so that the printing stability, the mechanical property and the uniformity of the sustained and controlled release of the medicine are ensured.

Further, in step 3, when the vessel stent to be printed is of a single-layer structure, only one printing nozzle may be selected to operate, and the vessel stent of the single-layer structure is printed.

Furthermore, the filler of the inner layer structure is a plasticizer or nano polymer particles or salt particles, preferably salt particles, the structural characteristics of the salt particles can be improved, the salt particles can be dissolved in water by soaking the aqueous solution in the post-treatment process to form a porous structure in the inner layer, the degradation speed of the salt particles can be accelerated to be matched with the degradation speed of the outer layer structure under the condition of not influencing the mechanical characteristics of the salt particles, and the adverse influence caused by too low degradation speed of the inner layer structure is avoided.

Further, in the step 3, a single-potential electric field driven jet 3D printing technology is adopted when the vascular stent is manufactured, and a grounded conductive substrate is not required to be used as a counter electrode. The method can ensure that metal materials such as glass, ceramics, stainless steel, titanium alloy, cobalt-based alloy and the like can be used as printing substrates, and is particularly suitable for conformal printing on curved surfaces and 3D surfaces.

Further, in step 3, the microscale 3D printing device may adjust the line width, the geometry, the porosity, and the like of the fabricated vascular stent by changing printing process parameters (voltage, distance between the nozzle and the substrate, duty ratio, frequency, back pressure, substrate rotation speed, and the like), and may realize the microscale high aspect ratio line structure by multilayer stacking by using the self-alignment effect of the electric field-driven jet 3D printing.

Further, in the step 3, the functional gradient layer printed by the functional gradient structure printing nozzle module may be a functional gradient layer with continuously changed components and ratio, or a gradient layer with fixed components and ratio, or a combination of the two; and the thickness of each layer is 2-100 μm.

Further, in the step 3, the micro-scale 3D printing blood vessel stent should be in a dust-free and sterile environment.

Further, in the step 4, the specific processing method is to put the printed blood vessel stent and the substrate into a solution to be soaked for several minutes, which may be an aqueous solution or other solutions with the same function, to dissolve the water-soluble material on the surface of the substrate into the aqueous solution, then manually peel off the blood vessel stent, and finally, dry the blood vessel stent.

Another object of the present invention is to provide a multi-nozzle micro-scale 3D printing apparatus for polymer fully degradable blood vessel stent, comprising: the device comprises a moving module, a rotary workbench, a composite material printing spray head module (printing spray head 1), a functional gradient structure printing spray head module (printing spray head 2), a functional gradient structure printing spray head feeding module, a composite material printing spray head feeding module, a high-voltage power supply module, a back pressure control module and a rack; the motion module is a gantry structure three-axis motion module and comprises an X axis, a Y axis and a Z axis, wherein the three axes are orthogonally arranged on stand columns of the rack, the X axis is vertically arranged on the double Y axes to form a gantry structure, and the Z axis is arranged on the X axis and is vertical to a horizontal plane; the rotary workbench is used for clamping the cylindrical base material to realize deposition molding of the printing material on the surface of the cylinder; the composite material printing spray head module is a fused deposition spray head and is used for printing thermoplastic composite materials and comprises a three-way joint, an annular heater, a connecting pipe heating block, a connecting pipe, a nozzle heating block and a nozzle; the three-way joint is respectively connected with the air pipe, the composite material printing nozzle feeding module and the nozzle 1, the three-way joint is wrapped with an annular heater, the backpressure of the printing nozzle is adjusted through a pressure regulating valve, the nozzle heating block is arranged on the nozzle 1, and the connecting pipe heating block keeps the printing material passing through the connecting pipe in a molten state; the functional gradient structure printing nozzle module is a multi-material active mixing nozzle, realizes feeding-mixing-extruding integrated printing of different printing materials by adopting a screw structure, and comprises a driving motor, a machine barrel, an annular heater, a nozzle heating block, a nozzle 2 and a single screw; the single screw is matched with the driving motor through the coupler and is coaxially arranged on the bracket with the machine barrel, the outer part of the machine barrel is wrapped with the annular heater, the nozzle 2 is arranged on the machine barrel, and the nozzle heating block can realize continuous heating of the nozzle 2; the functional gradient structure printing nozzle feeding module can supply printing materials in the forms of wires, particles, powder, liquid and the like to the printing nozzle; the composite material printing spray head feeding module adjusts the air pressure through the pressure adjusting valve to provide back pressure for the printing material, so that feeding into the composite material printing spray head is realized; the high-voltage power supply module comprises a high-voltage power supply and a signal generator, and the nozzles of the two printing spray head modules are connected with the positive pole of the high-voltage power supply.

Preferably, the mounting base is kept horizontal, and the gantry structure columns are equal in height and perpendicular to the mounting base.

Preferably, the Y-axis is driven by a double motor and the two Y-axis guide rails are kept parallel.

Preferably, the X, Z axis is driven by a linear motor and the Y axis is driven by a stepping motor.

Preferably, the effective X-axis stroke is 0-200mm, and the positioning is carried outThe precision is not less than +/-2 mu m, the repeated positioning precision is not less than +/-1 mu m, the maximum speed is 100mm/s, and the maximum acceleration is 1000m/s²(ii) a The effective travel of the Z axis is 0-100 μm, the positioning accuracy is not less than +/-2 μm, the repeated positioning accuracy is not less than +/-1 μm, the maximum speed is 50mm/s, and the maximum acceleration is 1000m/s²。

Preferably, the effective stroke of the Y axis is 0-200mm, the positioning precision is not less than +/-2 mu m, the repeated positioning precision is not less than +/-1 mu m, the maximum speed is 100mm/s, and the maximum acceleration is 1000m/s²。

Preferably, the coaxiality of the mounting holes of the rotary table is not less than 3 μm.

Preferably, the rotary table axis is parallel to the X-axis motion direction.

Preferably, the three-way joint of the print head 1 is made of an insulating material, such as glass, ceramic, and the like.

Preferably, the printing nozzle 1 feeding module adopts high-pressure high-purity inert gas to provide back pressure, the inert gas includes but is not limited to nitrogen, helium, argon, and the like, and the control range of the back pressure is as follows: 0.1-8 bar.

Preferably, the feed module is entirely surrounded by the ring heater.

Preferably, the material of the feed module and the material of the printing module connecting tube may be glass, ceramic, metal, etc., and the connecting tube may be equipped with a heating block.

Preferably, the printing nozzle 2 can realize the printing of a functional gradient structure, is provided with double feed inlets, and can realize the printing of materials in various forms such as silk materials, particles, powder, liquid and the like.

Preferably, the printing nozzle 2 adopts a screw structure, the mixing and pressure supply extrusion of printing materials are realized by the screw, and the diameter of the screw is 10-20 mm.

Preferably, the printing nozzle is a hidden needle, a glass needle (needle is sprayed with gold and is subjected to conductive treatment), a stainless steel nozzle and the like, and the inner diameter of the nozzle ranges from 1 to 200 mu m.

Preferably, the power supply adopts a high-voltage pulse power supply, the output pulse voltage is continuously adjustable from 0 kV to 5kV, and the output pulse frequency is from 0Hz to 3000 Hz.

Another object of the present invention is an application of the microscale 3D printing device for polymer fully-degradable vascular stents in printing polymer fully-degradable vascular stents.

Advantageous effects

The method, the device and the application thereof provided by the invention combine the advantages of the electric field driving jet 3D printing technology to realize the efficient and low-cost manufacture of the high-performance and structure-controllable polymer fully-degradable intravascular stent. It has the following significant advantages:

(1) the method adopts a single-potential electric field driving jet microscale 3D printing technology as a vascular stent manufacturing technology, a printing nozzle is connected with a high-voltage power supply, the manufacturing of the vascular stent with the microscale characteristic structure is realized by utilizing the diameter-reducing effect of an electrohydrodynamic Taylor cone, and the high-resolution printing of high-viscosity materials (biodegradable thermoplastic high polymer materials) can be realized under the action of electrostatic field tension (changing traditional pressure driving into tension driving).

(2) The manufacturing of the high-performance multifunctional intravascular stent is realized by adopting a plurality of spray heads (multiple materials), different materials are accurately sprayed and deposited by adopting a multi-spray head structure and the structure is formed according to the mechanical property, the degradation speed, the slow release and the controlled release of the drug and the like required by the intravascular stent, and the integrated manufacturing of shape control and controllability is realized.

(3) The method adopts a biodegradable thermoplastic high polymer material as a printing matrix material, such as polylactic acid, levorotatory polylactic acid, polyglycolic acid/polylactic acid copolymer, polycaprolactone, polyglycolic acid, polyhydroxybutyric acid and the like, and simultaneously prepares a composite material by adding medicaments (accelerating tissue growth, repair and the like) and enhancing items (enabling the manufactured vascular stent to achieve mechanical properties such as required strength, supporting force and the like), thereby solving the problems that the existing vascular stent has lower strength, is not matched with the mechanical property and the degradation speed, and particularly is difficult to realize accurate sustained release and controlled release of the medicaments.

(4) The material gradient change of the performance of the manufactured polymer fully-degradable intravascular stent on the space is realized by changing the proportion of additives of printing materials in the printing process of the printing nozzle with the screw rod structure, for example, the radial change of the concentration (content) of the drugs in the polymer fully-degradable intravascular stent is realized by changing the doping proportion of the drugs in real time in the printing process, so that the polymer fully-degradable intravascular stent has different drug slow-release speeds in the degradation process. Solves the difficult problems of accurate slow release and controlled release of the blood vessel stent medicament.

(5) By adjusting the technological parameters (power supply voltage, power supply duty ratio, power supply frequency, nozzle backpressure, needle point-substrate distance, substrate rotating speed and the like) of the electric field driven microscale 3D printing equipment, parameters such as the line width, the porosity, the diameter, the mesh structure size and the like of the intravascular stent can be accurately regulated and controlled, so that the controllable regulation of mechanical property, degradation speed and drug slow-release performance is realized.

(6) The cylindrical material is used as a printing substrate, the rotary motion of the cylindrical substrate is combined with the three-axis motion of a printing nozzle, and the efficient and low-cost manufacture of the hollow, cylindrical and reticular biopolymer full-degradable intravascular stent with high precision and high resolution (the minimum line width is 0.5 mu m) is realized on a cylindrical surface.

(7) The printing structure has high resolution, the printing line width is adjustable from several micrometers to hundreds of micrometers, and the printing structure has the characteristics of no limitation on the structure and the geometric dimension of the bracket and uniform and controllable porosity;

(8) the concentration of the drug loaded on the vascular stent is changed in a gradient manner in space, so that the slow release speed of the drug can be adjusted along with the degradation process of the polymer full-degradation vascular stent, the neointimal hyperplasia can be effectively inhibited, the restenosis rate can be reduced, and the target vascular revascularization rate can be reduced;

(9) improving the mechanical property of the polymer fully-degradable vascular stent by adding various enhancing items into the printing material;

(10) the printing substrate is wrapped by the water-soluble material, so that the adhesion effect of the printing material on the substrate is obviously improved, and the printed intravascular stent is convenient to take out of the printing substrate, so that the intravascular stent is prevented from being damaged;

(11) the method is suitable for printing various biodegradable polymer materials, and the printing material range is wide.

The invention can be applied to blood vessel stents, and can also be applied to hollow pipeline stents such as bile duct stents, urethral stents, ureteral stents, esophageal stents, tracheal stents, renal stents and the like.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application.

FIG. 1 is a flow chart of the method for printing the polymer fully degradable blood vessel stent of the invention.

Fig. 2 is a schematic diagram of the overall structure of a micro-scale 3D printer for manufacturing a polymer fully-degradable blood vessel stent according to an embodiment of the present invention.

Fig. 3 is a schematic structural diagram of a functionally graded printing nozzle and its feeding module according to an embodiment of the present invention.

Fig. 4 is a schematic structural diagram of a composite material print head according to an embodiment of the invention.

Fig. 5 is a schematic diagram of the inner and outer layer structure of the printed polymer fully degradable blood vessel stent of the embodiment of the invention.

Fig. 6 is a pictorial view of a blood vessel stent printed on a glass rod by the method and the device thereof.

Fig. 7 is a pictorial view of a blood vessel stent printed on a glass rod by the method and the device thereof.

Fig. 8 is a pictorial view of a vascular stent manufactured by the method and apparatus of the present invention.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

Examples of the embodiments

Referring to fig. 2, a schematic diagram of an overall structure of a micro-scale 3D printer for manufacturing a polymer fully-degradable vascular stent includes: the printing device comprises a moving module 1, a rotary workbench 2, a composite material printing nozzle module (printing nozzle 1)3, a functional gradient structure printing nozzle module (printing nozzle 2)4, a functional gradient structure printing nozzle feeding module 5, a composite material printing nozzle feeding module 6, a high-voltage power supply module 7, a backpressure control module 8 and a rack 9. The motion module 1 comprises an X axis 101, a double Y axis 102 and a Z axis 103, wherein the double Y axis 102 is arranged on a stand column 902 of the frame 9, the X axis 101 is vertically arranged on the double Y axis 102 to form a gantry structure, and the Z axis 103 is arranged on the X axis 101 and is vertical to a horizontal plane; the rotary worktable 2 mainly comprises a base plate 201, a bearing 202, a clamping head 203, a fixed bracket 204 and a motor 205. The clamping head 203 is arranged on the fixed support 204 through a bearing 202, meanwhile, the clamping head 203 is matched with the motor 205 through a coupler, the motor 205 is arranged on the fixed support 204, the fixed support 204 is fixed with a bottom plate 901 of the frame 9 through a bottom plate 201, and the axial direction of the rotary worktable 2 is parallel to the X axis 101; the composite material printing spray head (spray head 1)3 is positioned above the rotary worktable 2, is arranged on a bracket of the Z axis 103, and comprises a three-way joint 301, a ring heater 302, a connecting pipe heating block 303, a connecting pipe 304, a nozzle heating block 305 and a nozzle 306. The three-way joint 301 is respectively connected with an air pipe 803 of the backpressure control module 8, the composite material printing spray head feeding module 6 and the nozzle 306, the annular heater 302 is wrapped outside the three-way joint 301, one end of the air pipe 803 is connected with an air port of the three-way joint 301, the other end of the air pipe 803 is connected with the pressure regulating valve 801, the nozzle heating block 305 is installed on the nozzle 306, and the connecting pipe heating block 303 is installed on the connecting pipe 304; the functionally graded structure printing head (head 2)4 is located above the rotary table 2, is mounted on a bracket of the Z-axis 103, and comprises a driving motor 401, a cylinder 402, a ring heater 403, a nozzle heating block 404, a nozzle 405, and a single screw 406. The single screw 406 is matched with the driving motor 401 through a coupler and is coaxially arranged on the bracket with the cylinder 402, the cylinder 402 is wrapped with the annular heater 403, the nozzle 405 is arranged on the cylinder 402, and the nozzle heating block can realize continuous heating of the nozzle 405. The composite material printing spray head (spray head 1)3 and the functional gradient structure printing spray head (spray head 2)4 keep the spray nozzles at the same horizontal height; the functional gradient structure printing nozzle feeding module 5 changes the component proportion of the composite material by changing the feeding speeds of the material 1 feeding device 501 and the material 2 feeding device 502 in the printing process, so that the printing structure presents gradient change in space; the composite material printing spray head feeding module 6 adjusts the air pressure through the pressure adjusting valve 802 to provide back pressure for printing materials, feeding into the composite material printing spray head 3 is achieved, the composite material printing spray head feeding module and the composite material printing spray head feeding module are communicated through a connecting pipe 304, and the composite material printing spray head feeding module 6 is wrapped with an annular heater and is installed on a support of the Z shaft 103; the high-voltage power supply module 7 comprises a high-voltage power supply 701 and a signal generator 702, and the nozzles of the two printing spray head modules are connected with the positive pole of the high-voltage power supply 701.

The method for printing the polymer fully-degradable vascular stent by adopting the structure shown in FIG. 2 comprises the following steps:

step 1: printing substrate pretreatment

The printing substrate adopts a glass rod-shaped substrate, and the diameter of the substrate is 4 mm. Firstly, placing a glass rod (printing substrate) in physiological saline, carrying out ultrasonic treatment for 30min, drying the glass rod subjected to ultrasonic treatment by nitrogen, then placing the glass rod in medical alcohol for ultrasonic treatment for 30min, and then drying the glass rod by high-purity nitrogen; sterilizing the cleaned glass rod, placing the glass rod in a pulsating vacuum pressure steam sterilizer by adopting a high-pressure steam sterilization method, and adjusting equipment parameters: steam pressure 205.8kPa (2.1 kg/cm)²) The temperature reaches over 132 ℃, the temperature is maintained for 10 minutes under the parameters, and finally the glass rod is taken out for standby.

Step 2: guiding the blood vessel stent printing path, preparing the printing material and placing the printing material in a printing device

The polymer fully-degradable intravascular stent printed in the embodiment is of an inner-layer structure and an outer-layer structure, the cylindrical surface development structures of the inner-layer structure and the outer-layer structure are shown in fig. 5, the printing line width of the inner-layer structure is 20 micrometers, the base material is levorotatory polylactic acid (PLLA), the filler is salt particles (strengthening items), the base material and the filler are put into a mixing device and are uniformly mixed at the temperature of 200-220 ℃, and the mixed printing material is put into a storage tank and is placed into a composite material printing nozzle feeding module 6 for standby; the printing line width of the outer layer structure is 2 μm, the base material is polycaprolactone (PCL, silk material), the filler is rapamycin (powder), and the base material and the filler are respectively placed in the material 1 feeding device 501 and the material 2 feeding device 502.

And step 3: microscale 3D prints intravascular stent

Printing an inner layer structure: the inner layer is of a skeleton structure and provides enough mechanical properties

(1) For printing initialization, the nozzle 306 is moved to the printing original position so as to be above the substrate axis, and the height of the nozzle 306 from the substrate is 200 μm and 500 μm. According to the melting point of the printing material with the inner layer structure, the temperature of the feeding module, the annular heater 302 of the spray head module and the heating block 303 of the connecting pipe is set to be 200 ℃, the inner diameter of the nozzle is set to be 200 mu m, the temperature of the heating block 305 of the nozzle is set to be 180 ℃, and the temperature of the nozzle 306 is ensured to accurately meet the printing requirement.

(2) Opening the back pressure of the storage barrel, adjusting the air pressure value of the pressure regulating valve 802 to be 4-5kPa, starting feeding to the composite material printing nozzle 3, opening the back pressure of the nozzle module, adjusting the air pressure value of the pressure regulating valve 801 to be 3-3.5kPa, opening the high-voltage power supply 701, adjusting the voltage value to be 1000-1200V, extruding the printing material to the tip of the nozzle 306, and stretching and deforming under the comprehensive actions of electric field force, surface tension, viscous force and the like to gradually form conical jet flow.

(3) The high-precision manufacturing of the mesh structure on the rod-shaped substrate is realized by combining the movement of the nozzle 306 and the rotation of the substrate, as shown in fig. 5(a), the printing nozzle 306 reciprocates along the X-axis direction, the moving speed is 10mm/s, the moving stroke is 50mm, the rotating table 2 keeps the rotating speed at 5r/s, and the printing thickness of the inner layer structure is 120 μm.

(4) After the printing of the inner layer structure is finished, the high voltage power supply and the back pressure are turned off, the heaters are turned off, the printing nozzle 306 is moved to the printing origin, and the rotary table 2 is returned to the initial position.

Printing an outer layer structure: the outer layer is a high-porosity drug slow-release structure, which is beneficial to cell adhesion, growth and proliferation

(1) The printing nozzle 4 with the functional gradient structure is switched, PCL and rapamycin are fed into the cylinder 402 by the material 1 feeding device 501 and the material 2 feeding device 502 according to the designed functional gradient structure in proportion (the feeding proportion can be adjusted in the printing process), the rotating speed of the screw driving motor 401 is adjusted to enable the extruding speed of the printing material to be matched with the feeding speed, the temperature of the annular heater 403 is set to be 100 ℃, the inner diameter of the nozzle is set to be 200 mu m, the temperature of the heater of the nozzle 405 is set to be 90 ℃ according to the melting point of the printing material, and the temperature of the nozzle 405 is ensured to accurately meet the printing requirement.

(2) And (3) starting a high-voltage power supply 701, adjusting the voltage value to be 1300-1600V, extruding the printing material to the tip of the nozzle 405, and stretching and deforming under the comprehensive actions of electric field force, surface tension, viscous force and the like to gradually form ultrafine cone jet flow.

(3) High-precision manufacturing of a lattice structure on a bar-shaped substrate is realized by combining the movement of the nozzle 405 and the rotation of the substrate, and as shown in fig. 5(b), the printing nozzle 405 reciprocates in the X-axis direction at a movement speed of 20mm/s and a movement stroke of 50mm, the rotation speed of the rotary table 2 is 10r/s, and the printing thickness of the outer layer structure is 100 μm.

(4) And after the printing of the outer layer structure is finished, the high-voltage power supply and the backpressure are closed, the heaters are closed, the printing nozzle is moved to the original point of the device, and the printing substrate is taken down.

And 4, step 4: intravascular stent post-treatment

The blood vessel that will print the completion is taken out from printing the base, can wholly place the blood vessel support of printing in aqueous solution (solution does not have the influence to blood vessel support and base itself, only changes the adhesion effect between blood vessel support and the base) with printing the base in order to avoid damaging the blood vessel support and peel off, simultaneously, salt granule in the inner layer structure makes the inner layer structure become porous structure (compromise mechanical properties and degradation speed simultaneously) in aqueous. Finally, the size of the blood vessel stent is cut.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.