3D printing composite microfiber scaffold and preparation method thereof

Abstract

The invention discloses a 3D printing composite microfiber scaffold and a preparation method thereof, and relates to the fields of material processing, high polymer materials and biomedical materials. Structural design and wiredrawing path design of the microfiber scaffold are carried out through three-dimensional modeling, G-code is written to enable the length and diameter of stretched microfibers to be controllable, a customized composite microfiber scaffold with a multi-dimensional space structure is formed, microfibers and crude fibers which are smaller in size, accurate and controllable are printed in the same entity at the same time, and the production efficiency is improved. The scaffold has customizable microfiber size distribution and space structure, is beneficial to a microenvironment of cell activity, and has a wide application prospect in the field of tissue engineering scaffolds.

Description

Technical Field

[0001] The present invention relates to the fields of material processing, polymer materials and biomedical materials, and in particular to a 3D printed composite microfiber scaffold and a preparation method thereof. Background Art

[0002] Clinically, bone injury and bone defect caused by accidents or diseases is the most common trauma. In the process of repairing bone injury and bone defect, cells and tissues are involved. It is a delicate and complex regeneration process, which has high research value in the field of biomedical engineering.

[0003] Bone repair scaffolds have a wide range of clinical application potential, including fracture repair and bone defect treatment. These scaffolds are designed to mimic the structure and composition of natural bone to promote the growth of new tissue. Bone tissue regeneration scaffolds are constantly developing around the requirements of providing a microenvironment for cell life activities, providing space and raw materials for mineralization, promoting cell differentiation and bone regeneration, and playing a role in supporting and assisting various physiological functions of cell and bone tissue regeneration. They are often used in the preparation of bone tissue regeneration scaffolds to improve the biological activity of bone repair scaffolds.

[0004] In recent years, the combination of biology and engineering has greatly promoted the depth and breadth of research in the field of biomedical engineering. Bone tissue engineering mainly includes three elements: scaffolds, cells and growth factors. The three elements work together to achieve efficient simulation of natural bone repair and regeneration. Bone repair and regeneration are completed through the mechanism of bone induction (implant materials stimulate mesenchymal stem cells around the bone graft area to differentiate into chondrocytes or osteoblasts), osteoconduction (the host bone in the bone graft area combines with the surface of the implant material to guide the formation of surrounding bones) and bone formation (the material has the function of promoting osteoblast differentiation and has a bone formation effect). Traditional bone repair scaffolds are mainly made by gas foaming, particle leaching, freeze casting and other methods. The emergence of 3D printing technology has brought revolutionary breakthroughs to biomedical engineering. 3D printing technology can accurately control and prepare various complex internal and external structures, and has great potential in tissue regeneration and bone repair. Customizable fiber scaffolds have gradually become an important research direction. The combination of 3D printing technology and material surface activation to reproduce the natural process of mineral formation in organisms is an emerging research direction.

[0005] In the scaffold, the presence of fibers can play a role in mechanical enhancement. The staggered fibers can effectively improve the overall strength of the scaffold. At the same time, since the size of the fibers is closer to that of the cells, the cell adhesion and retention effects can be improved, and the overall biological properties of the scaffold can be improved. The diameter of conventional coarse fibers is usually between 200-600 μm, in which the role of the fibers is mainly to provide a certain mechanical strength through fiber reinforcement, provide mechanical support and toughening effects, but the cell adhesion environment is poor. Micron and nanofibers are closer to the cell scale, have good biological properties, and show good cell adhesion and retention effects. They can effectively promote the osteogenic differentiation of stem cells and accelerate bone regeneration. At present, micro-nano fibers are mainly prepared by electrospinning, electrostatic direct writing and other methods. The fiber diameter can reach the nanometer level. However, electrospinning can only generate disordered fiber membranes without spatial structure. Preparation methods such as electrostatic direct writing 3D printing have high requirements for equipment and high technical difficulty, and it is difficult to take into account the simultaneous printing of fibers of different sizes. Due to the small fiber diameter, the mechanical properties of micro-nano fiber scaffolds are poor, which hinders their further application in bone regeneration and repair scaffolds.

[0006] Therefore, providing a microfiber scaffold that can simultaneously provide a good tissue regeneration microenvironment and certain mechanical properties, and can prepare a customizable microfiber scaffold with a regular spatial structure through simple technology and manufacturing process, has become a problem that technicians in this field urgently need to solve. FDM 3D printing uses thermoplastic linear materials as raw materials, with simple equipment, stable process, fast printing speed, and high raw material utilization rate, so it is widely used. The thermoplastic wire is heated and melted into a molten state at the hot melt nozzle, extruded from the nozzle, and printed layer by layer on the workbench. During the printing process, the wire is in a molten state. When the wire has not yet solidified, the rapid movement of the nozzle will cause a "wire drawing" phenomenon. Using this principle, the microfiber scaffold disclosed in the present invention can be obtained. Summary of the invention

[0007] The purpose of the present invention is to provide a 3D printed composite microfiber scaffold and a preparation method thereof, which can realize the control of microfiber diameter and synchronous printing by controlling the FDM "wire drawing" phenomenon. The prepared spatially structured microfiber scaffold can be used as a scaffold in bone tissue regeneration and repair, provide a good cell microenvironment and certain mechanical properties, and have good osteogenic properties.

[0008] The 3D printed composite microfiber scaffold provided by the present invention comprises a mineralized microfiber scaffold with pure microfibers inside and a composite fiber scaffold with a surrounding scaffold constructed of coarse fibers.

[0009] In some embodiments of the present invention, the 3D printed microfiber scaffold is made of a thermoplastic polymer material.

[0010] Preferably, the 3D printed composite microfiber scaffold can be made of one or two materials selected from the group consisting of polylactic acid, polycaprolactone, and polyetheretherketone.

[0011] In some embodiments of the present invention, the 3D printed composite microfiber scaffold uses a melt extrusion 3D printer.

[0012] Preferably, the 3D printed composite microfiber scaffold uses a dual-nozzle melt extrusion type 3D printer, the printer has two independent nozzles, each nozzle is set with a nozzle temperature, an extruder retraction speed, a printing speed and a filling density;

[0013] Preferably, the main fiber diameter in the 3D printed composite microfiber scaffold is 200-600 μm;

[0014] Preferably, the diameter of the microfibers in the 3D printed composite microfiber scaffold is 20-180 μm;

[0015] Preferably, the diameter of the microfibers in the 3D printed composite microfiber scaffold is 50-100 μm.

[0016] In order to achieve the above-mentioned purpose of preparing the 3D printed composite microfiber scaffold, the preparation scheme adopted by the present invention is as follows:

[0017] S1. Construction and path setting of microfiber scaffold model:

[0018] The microfiber scaffold model is designed by modeling and the path is set by G-code. The specific steps include:

[0019] S11. 3D modeling of fiber scaffold;

[0020] S12. Slicing the model: importing the 3D fiber scaffold model modeled in S11 into 3D printing slicing software (such as Ultimaker Cura), performing preliminary setting of printing parameters, and slicing the printed model;

[0021] S13. Writing G-code for the slicing program: Find the area code that needs microfiber printing in the G-code obtained after slicing, and insert and write the microfiber printing code according to different microfiber lengths, spacing distances, thicknesses, arrangement methods and other performance requirements;

[0022] S2. Microfiber support printing support

[0023] S21. Printing of the bracket body: directly use the FDM printer to run the G-code obtained through the slicing program to print the bracket body;

[0024] S22. Preparation of microfibers: Under the control of the G-code code, the nozzle stops extrusion after printing an end point on the main support, and the nozzle does not perform a retraction operation. Then the nozzle moves quickly according to the preset microfiber printing path, and drives to the other end point corresponding to the microfiber on the main support. After the material deposited by the printing nozzle is stretched to the appropriate position, the nozzle continues printing to achieve the preparation of microfibers.

[0025] S23. Preparation of microfiber scaffolds: The structure adopts a microfiber printing in each layer in the G-code code, and the microfiber direction between layers is 90°, thereby forming a multi-layer microfiber scaffold with an orthogonal structure;

[0026] In some embodiments of the present invention, the microfibrous scaffold is calcium phosphate deposited in an orderly manner on the microfibrous scaffold to obtain a biomimetic mineralized microfibrous scaffold, which can enhance the ability of bone tissue repair and regeneration.

[0027] Preferably, in step S22, the idle speed of the nozzle is set to 6000-9000 mm / min through the G-code code, so that microfibers of different diameters can be prepared.

[0028] Preferably, in step S22, the print nozzle temperature is set to 235-245°C through the G-code code.

[0029] The microfiber scaffold prepared by the present invention is immersed in a sodium hydroxide aqueous solution for 4-10 hours, or a mixed solution of a sodium hydroxide aqueous solution and ethanol (v / v=1 / 1) for 6-12 hours, taken out and rinsed with deionized water three times, frozen at -20°C overnight, and then freeze-dried. The microfiber scaffold treated with surface alkali is then incubated in a simulated body fluid with a calcium and phosphate ion concentration 10 times that of human plasma for 1-4 hours, and then freeze-dried to obtain a mineralized microfiber scaffold.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention utilizes the "drawing" phenomenon that occurs in the FDM printer, and through the setting of parameters and paths, the "drawing" phenomenon is successfully controlled by G-code code writing. Through the controllable "drawing" phenomenon, microfibers with a diameter of 20-180μm can be prepared using an ordinary FDM printer. Compared with electrostatic direct writing or modified customized high-precision 3D printers, the present invention has greatly improved the equipment requirements and technical difficulty. At the same time, the use of 3D printing additive manufacturing technology to prepare microfibers solves the problem of disordered arrangement of microfibers prepared by electrospinning, and solves the problem of no spatial structure of microfibers prepared by electrospinning. Through additive manufacturing technology, the scaffold can be modeled to prepare a customizable microfiber scaffold with an orderly arrangement of spatial structure. Compared with a single-layer electrospinning fiber membrane, this 3D printed microfiber scaffold prepared based on FDM upgrades the fiber structure from a two-dimensional planar structure to a three-dimensional structure, increases the load of the scaffold on cells, and provides an environment that is more biomimetic to the physiological environment of natural cells, thereby improving the efficiency of tissue repair. In this way, this 3D printed microfiber scaffold can break the technical barriers for the preparation of customizable microfiber scaffolds with orderly arrangement of spatial structures, greatly reducing equipment requirements and technical difficulty.

[0032] In addition, the composite microfiber scaffold designed by the present invention that combines coarse and fine fibers has significant advantages in bone tissue engineering. Compared with other fiber scaffolds with a single structure, the composite microfiber scaffold designed by the present invention is structurally formed by stacking coarse and fine fibers layer by layer, which can fully simulate the multilayer structure of the tissue; the arrangement, diameter and orientation of the fibers in each layer can be accurately controlled. Uniformly arranged microfibers (diameter 20-180 μm) are superimposed on the coarse fibers (diameter 200-600 μm) of the orthogonal structure. Since the size scale of cells (20 μm) is closer to the size scale of microfibers than the size scale of coarse fibers, cells are easy to adhere to thinner microfibers and maintain a higher proliferation rate. In addition, cells span the pores to form cell sheets, and gradually migrate to the coarse fibers to cover the entire scaffold. Compared with traditional coarse fiber scaffolds, the composite microfiber scaffold designed by the present invention that combines coarse and fine fibers can provide a microenvironment that is more conducive to cell adhesion. At the same time, due to the diameter of the microfibers, current microfiber scaffolds generally do not have good mechanical properties. In the composite microfiber scaffold designed by the present invention, the main coarse fiber scaffold can provide certain mechanical properties, and protect the microfibers inside and between layers as a support, preventing the microfiber scaffold from structural deformation or collapse. In this way, the 3D printed microfiber scaffold prepared based on FDM provides a certain mechanical strength and a cell microenvironment that is conducive to cell adhesion, improving the poor cell adhesion environment of traditional coarse fiber scaffolds and the low mechanical strength of ordinary microfiber scaffolds. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Attached Figure 1 This is the appearance diagram of the 3D printed composite microfiber scaffold of Example 1.

[0034] Attached Figure 2 This is an SEM image of the microfiber effect in the 3D printed composite microfiber microfiber scaffold of Example 1.

[0035] Attached Figure 3 This is an SEM image of the microfiber effect in the 3D printed composite microfiber microfiber scaffold of Example 2.

[0036] Attached Figure 4 This is an SEM image of the microfiber effect in the 3D printed composite microfiber microfiber scaffold of Example 3.

[0037] Attached Figure 5 This is an SEM image of the microfiber effect in the 3D printed composite microfiber microfiber scaffold of Example 4.

[0038] Attached Figure 6 This is an SEM image of the microfiber effect in the 3D printed composite microfiber microfiber scaffold of Example 5.

[0039] Attached Figure 7 This is an SEM image of the microfiber effect in the 3D printed composite microfiber microfiber scaffold of Example 6.

[0040] Attached Figure 8 This is a graph showing the TGA thermogravimetric analysis results of the mineralization effect of the microfiber scaffolds with different surface treatments and different mineralization incubation times in Example 1.

[0041] Attached Fig. 9 This is a graph showing the results of investigating the mechanical tensile properties of the microfiber scaffolds surface-treated under different conditions and the microfiber scaffolds after mineralization in Example 1. DETAILED DESCRIPTION

[0042] To make the purpose, technical scheme and advantages of the embodiment of the present invention clearer, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the illustrations in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the art without making creative work are within the scope of protection of the present invention. If the specific conditions are not indicated in the embodiment, it is carried out according to the normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0043] In order to achieve the above-mentioned purpose of preparing the 3D printed microfiber scaffold, the preparation scheme adopted by the present invention is as follows:

[0044] Example 1

[0045] A 3D printed microfiber scaffold preparation scheme is as follows:

[0046] S1. Construction and path setting of microfiber scaffold model:

[0047] Design the microfiber scaffold model through modeling and set the path through G-code code; including:

[0048] S11. 3D modeling of fiber scaffold;

[0049] S12. Slicing the model: importing the 3D fiber scaffold model modeled in S11 into 3D printing slicing software (such as Ultimaker Cura), performing preliminary setting of printing parameters, and slicing the printed model;

[0050] S13. Write G-code for the slicing program: Find the area code where microfiber printing is required in the G-code obtained after slicing, set the printing nozzle temperature to 235°C and the nozzle idle speed to 9000mm / min through the G-code, and obtain microfibers with a diameter of 20μm;

[0051] S2. Microfiber support printing support

[0052] S21. Printing of the bracket body: directly use the FDM printer to run the G-code obtained through the slicing program to print the bracket body;

[0053] S22. Preparation of microfibers: Under the control of the G-code code, the nozzle stops extrusion after printing an end point on the main support, and the nozzle does not perform a retraction operation. Then the nozzle moves quickly according to the preset microfiber printing path, and drives to the other end point corresponding to the microfiber on the main support. After the material deposited by the printing nozzle is stretched to the appropriate position, the nozzle continues printing to achieve the preparation of microfibers.

[0054] S23. Preparation of microfiber scaffolds: The structure adopts a microfiber printing in each layer in the G-code code, and the microfiber direction between layers is 90°, thereby forming a multi-layer microfiber scaffold with an orthogonal structure;

[0055] Example 2

[0056] The difference from Example 1 is that:

[0057] In step S13, the temperature of the printing nozzle is set to 235°C through the G-code code, and the idle speed of the nozzle is set to 7000 mm / min, so that microfibers with a diameter of 60 μm can be obtained;

[0058] The rest is consistent with Example 1.

[0059] Example 3

[0060] The difference from Example 1 is that:

[0061] In step S13, the temperature of the printing nozzle is set to 235°C through the G-code code, and the idle speed of the nozzle is set to 6000 mm / min, so that microfibers with a diameter of 80 μm can be obtained;

[0062] In step S3, the microfiber scaffolds printed in S23 were subjected to surface alkali treatment with 0.5 mol / L sodium hydroxide aqueous solution for 4 h.

[0063] Example 4

[0064] The difference from Example 1 is that:

[0065] In step S13, the temperature of the printing nozzle is set to 240°C through the G-code code, and the idle speed of the nozzle is set to 7000 mm / min, so that microfibers with a diameter of 100 μm can be obtained;

[0066] The rest is consistent with Example 1.

[0067] Example 5

[0068] The difference from Example 1 is that:

[0069] In step S13, the temperature of the printing nozzle is set to 230°C through the G-code code, and the idle speed of the nozzle is set to 8000 mm / min, so that microfibers with a diameter of 120 μm can be obtained;

[0070] The rest is consistent with Example 1.

[0071] Example 6

[0072] The difference from Example 1 is that:

[0073] In step S13, the temperature of the printing nozzle is set to 230°C through the G-code code, and the idle speed of the nozzle is set to 6000 mm / min, so that microfibers with a diameter of 150 μm can be obtained;

[0074] The rest is consistent with Example 1.

[0075] Example 7

[0076] The difference from Example 1 is that:

[0077] In step S13, the temperature of the printing nozzle is set to 230°C through the G-code code, and the idle speed of the nozzle is set to 5000 mm / min, so that microfibers with a diameter of 180 μm can be obtained;

[0078] The rest is consistent with Example 1.

Claims

1. A 3D printed composite microfiber scaffold, characterized in that: It includes a mineralized microfiber scaffold with pure microfibers inside and a composite fiber scaffold with a peripheral scaffold constructed by coarse fibers.

2. The 3D printed composite microfiber scaffold according to claim 1, characterized in that: It can be prepared from one or two thermoplastic polymer materials selected from polylactic acid, polycaprolactone and polyetheretherketone.

3. The 3D printed composite microfiber scaffold according to claim 1, characterized in that: The diameter of the coarse fibers in the scaffolds was 200-600 μm.

4. The 3D printed composite microfiber scaffold according to claim 1, characterized in that: The diameter of microfibers in the scaffolds ranged from 20 to 180 μm.

5. The composite microfiber scaffold prepared by 3D printing according to claim 1, characterized in that: The diameter of microfibers in the scaffolds is 20-100 μm.

6. The composite microfiber scaffold prepared by 3D printing according to claim 1, characterized in that: The diameter of microfibers in the scaffolds was 20-60 μm.

7. The 3D printed composite microfiber scaffold according to any one of claims 1 to 6, characterized in that: The microfiber scaffold preparation method comprises: S1. Construction and path setting of microfiber scaffold model: The microfiber scaffold model is designed by modeling and the path is set by G-code. The specific steps include: S11. 3D modeling of fiber scaffold; S12. Slicing the model: importing the 3D fiber scaffold model modeled in S11 into 3D printing slicing software (such as Ultimaker Cura), performing preliminary setting of printing parameters, and slicing the printed model; S13. Write G-code for the slicing program: Find the area code that needs microfiber printing in the G-code code obtained after slicing, and insert and write the microfiber printing temperature, printing speed, and path control code according to different microfiber length, spacing distance, thickness, arrangement and other performance requirements; S2. Microfiber support printing support S21. Printing of the bracket body: directly use the FDM printer to run the G-code obtained through the slicing program to print the bracket body; S22. Preparation of microfibers: Under the control of the G-code code, the nozzle stops extrusion after printing an end point on the main support, and the nozzle does not perform a retraction operation. Then the nozzle moves quickly along the preset microfiber printing path, and drives to the other end point corresponding to the microfiber on the main support. After the material deposited by the printing nozzle is stretched to the preset position, the nozzle continues printing to achieve the preparation of microfibers. S23. Preparation of microfiber scaffold: The structure adopts the printing of microfibers in each layer in the G-code code, and the direction of microfibers between layers is 90°, thereby forming a multi-layer microfiber scaffold with an orthogonal structure.

8. The method for preparing a 3D printed composite microfiber scaffold according to claim 7, characterized in that: In S13, the printing nozzle temperature is 235-245° C., and the printing speed is set to 6000-9000 mm / min.

9. The method for preparing a 3D printed composite microfiber scaffold according to claim 7, characterized in that: In S13, the printing speed is set to 6000-9000 mm / min.

10. The method for preparing a 3D printed composite microfiber scaffold according to claim 7, characterized in that: In S23, the microfiber support structure is formed by printing microfibers once in each layer in the G-code code, and the direction of the microfibers between layers is 90 degrees, thereby forming a multi-layer microfiber support with an orthogonal structure.

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