3D printing composite microfiber scaffold and preparation method thereof

Abstract

The application discloses a 3D printing composite micro-fiber support and a preparation method, and relates to the fields of material processing, polymer materials and biomedical materials. The application designs the structure and drawing path of the micro-fiber support through three-dimensional modeling, and writes G-code to control the length and diameter of the drawn micro-fiber, so that a customized composite micro-fiber support with a multi-dimensional space structure is formed, the micro-fiber and the coarse fiber with smaller size and accurate control are printed in the same entity, the micro-fiber has a customizable size distribution and space structure, and the micro-fiber is beneficial to the micro-environment of cell activity, so that the application has a wide application prospect in the field of tissue engineering supports.

Description

Technical Field

[0001] This invention relates to the fields of materials processing, polymer materials and biomedical materials, and specifically to a 3D printed composite microfiber scaffold and its preparation method. Background Technology

[0002] Bone injuries and defects caused by accidents or diseases are among the most common types of trauma in clinical practice. The repair process of bone injuries and defects involves cells and tissues, and is a delicate and complex regenerative process with high research value in the field of biomedical engineering.

[0003] Bone repair scaffolds have broad clinical application potential, including fracture repair and treatment of bone defects. 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 continuously evolving to meet the requirements of providing a microenvironment for cellular life activities, providing space and raw materials for mineralization, promoting cell differentiation, and facilitating bone regeneration, thus playing a supporting and assisting role in various physiological functions of cell and bone tissue regeneration. They are commonly used in the preparation of bone tissue regeneration scaffolds to enhance their bioactivity.

[0004] In recent years, the integration 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. These three elements coordinate and cooperate to achieve efficient simulation of natural bone repair and regeneration. Bone repair and regeneration are accomplished through mechanisms such as osteoinduction (the implanted material stimulates mesenchymal stem cells around the bone graft site to differentiate into chondrocytes or osteoblasts), osteoconduction (the host bone in the bone graft site combines with the surface of the implanted material, guiding surrounding bone formation), and bone formation (the material has the function of promoting osteoblast differentiation, thus playing a role in bone formation). Traditional bone repair scaffolds are mainly made by methods such as gas foaming, particle leaching, and cryogenic casting. The emergence of 3D printing technology has brought a revolutionary breakthrough to biomedical engineering. 3D printing technology can precisely control and prepare various complex internal and external structures, showing great potential in tissue regeneration and bone repair. Customizable fiber scaffolds are gradually becoming an important research direction. Utilizing 3D printing technology combined with material surface activation to reproduce the natural process of mineral formation in the body is an emerging research direction.

[0005] In scaffolds, fibers provide mechanical reinforcement. Interlaced fibers effectively enhance the overall strength of the scaffold. Furthermore, because the size of fibers is closer to that of cells, they improve cell adhesion and retention, thus enhancing the overall biological performance of the scaffold. Conventional coarse fibers typically have a diameter between 200-600 μm. Their main function is to provide mechanical strength, support, and toughening through fiber reinforcement, but they offer poor cell adhesion. Microfibers and nanofibers, being closer to the cellular scale, possess excellent biological properties, exhibiting good cell adhesion and retention, effectively promoting osteogenic differentiation of stem cells and accelerating bone regeneration. Currently, microfibers and nanofibers are mainly prepared using methods such as electrospinning and electrostatic direct writing, achieving nanometer-scale fiber diameters. However, electrospinning can only generate disordered fiber membranes without spatial structure, while methods like electrostatic direct writing 3D printing require sophisticated equipment and are technically challenging, making it difficult to simultaneously print fibers of different sizes. Due to the small fiber diameter, microfiber and nanofiber scaffolds exhibit poor mechanical properties, hindering their further application in bone regeneration and repair scaffolds.

[0006] Therefore, providing a microfiber scaffold that can simultaneously offer a favorable tissue regeneration microenvironment and certain mechanical properties, and that can be fabricated using simple techniques and manufacturing processes to create customizable microfiber scaffolds with regular spatial structures, has become a problem urgently needing to be solved by those skilled in the art. FDM 3D printing, using thermoplastic filaments as raw materials, is widely used due to its simple equipment, stable process, fast printing speed, and high raw material utilization. Thermoplastic filaments are heated and melted at the hot melt nozzle, then extruded from the nozzle and printed layer by layer on the worktable. During the printing process, the filaments are in a molten state; before the filaments solidify, the rapid movement of the nozzle can cause a "filamentation" phenomenon. Using this principle, the microfiber scaffold disclosed in this invention can be obtained. Summary of the Invention

[0007] The purpose of this invention is to provide a 3D printed composite microfiber scaffold and its preparation method. By controlling the "fiber drawing" phenomenon of FDM, the diameter of the microfibers can be controlled and printed synchronously. The prepared spatially ordered microfiber scaffold can be used as a scaffold in bone tissue regeneration and repair, providing a good cellular microenvironment and certain mechanical properties, and has good osteogenic properties.

[0008] The 3D printed composite microfiber scaffold provided by the present invention consists of a mineralized microfiber scaffold with a pure microfiber interior 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 thermoplastic polymer material.

[0010] Preferably, the 3D printed composite microfiber scaffold can be prepared from one or two of the following materials: polylactic acid, polycaprolactone, and polyetheretherketone.

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

[0012] Preferably, the 3D printed composite microfiber scaffold uses a dual-nozzle melt extrusion 3D printer, which has two independent nozzles, each with its own nozzle temperature, extruder retraction speed, printing speed and infill density.

[0013] Preferably, the diameter of the main fiber 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] To achieve the aforementioned objective of fabricating 3D-printed composite microfiber scaffolds, the fabrication scheme employed in this invention is as follows:

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

[0018] The microfiber scaffold model is designed through modeling and the path is set using G-code; the specific operation steps include:

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

[0020] S12. Slice the model: Import the 3D fiber scaffold model created in S11 into 3D printing slicing software (such as Ultimaker Cura), set the initial printing parameters, and slice the printed model.

[0021] S13. Write G-code for the slicing program: Find the area code that needs to be printed with microfibers in the G-code obtained after slicing, and insert and write the microfiber printing code according to the performance requirements such as different microfiber length, spacing, thickness, and arrangement.

[0022] S2. Microfiber scaffold printing scaffold

[0023] S21. Printing of the main body of the bracket: The main body of the bracket is printed by directly running the G-code obtained through the slicing program using an FDM printer;

[0024] S22. Microfiber preparation: Under the control of G-code, the nozzle pauses extrusion after printing to one end of the main support. The nozzle does not perform a retraction operation. Then, the nozzle moves quickly according to the preset microfiber printing path, runs empty to the other end of the main support corresponding to the microfiber, stretches the material deposited by the printing nozzle to a suitable position, and then the nozzle continues printing to achieve microfiber preparation.

[0025] S23. Fabrication of microfiber scaffolds: The structure is formed by printing microfibers one layer at a time in G-code, with the microfiber orientation between layers at 90°, thus forming an orthogonal multilayer microfiber scaffold.

[0026] In some embodiments of the present invention, the microfiber scaffold is formed by the orderly deposition of calcium phosphate on the microfiber scaffold, resulting in a biomimetic mineralized microfiber scaffold that can enhance the ability of bone tissue to repair and regenerate.

[0027] Preferably, in step S22, the no-load speed of the nozzle is set to 6000-9000 mm / min using G-code, which can enable the preparation of microfibers of different diameters.

[0028] Preferably, in step S22, the printing nozzle temperature is set to 235-245℃ using G-code.

[0029] The microfiber scaffold prepared according to this invention is immersed in an aqueous sodium hydroxide solution for 4-10 hours, or in a mixed solution of sodium hydroxide solution and ethanol (v / v = 1 / 1) for 6-12 hours. It is then removed, rinsed three times with deionized water, frozen overnight at -20°C, and then freeze-dried. The microfiber scaffold, after surface alkali treatment, is incubated in a simulated body fluid with a calcium and phosphorus ion concentration 10 times that of human blood 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] This invention utilizes the "fiber-drawing" phenomenon observed in FDM printers. By setting parameters and paths, and through G-code programming, this "fiber-drawing" phenomenon can be successfully controlled. This controllable "fiber-drawing" phenomenon allows for the fabrication of microfibers with diameters ranging from 20-180 μm using ordinary FDM printers. Compared to electrostatic direct-write printing or modified high-precision 3D printers, this invention significantly improves upon traditional methods in terms of equipment requirements and technical difficulty. Furthermore, the use of 3D printing additive manufacturing technology for microfiber fabrication solves the problems of disordered arrangement and lack of spatial structure in electrospinning-based microfibers. Additive manufacturing technology allows for scaffold modeling, enabling the fabrication of customizable microfiber scaffolds with ordered spatial arrangements. Compared to single-layer electrospun fiber membranes, this FDM-based 3D-printed microfiber scaffold elevates the fiber structure from a two-dimensional planar structure to a three-dimensional structure, increasing the scaffold's load-bearing capacity for cells. The environment it provides is more biomimetic to the physiological environment of natural cells, thus improving tissue repair efficiency. Thus, this 3D-printed microfiber scaffold can break through the technical barriers to the fabrication of customizable microfiber scaffolds with ordered spatial structures, greatly reducing equipment requirements and technical difficulty.

[0032] Furthermore, the composite microfiber scaffold combining coarse and fine fibers designed in this invention has significant advantages in bone tissue engineering. Compared to other single-structure fiber scaffolds, the composite microfiber scaffold designed in this invention is structurally formed by the layering of coarse and fine fibers, which can fully simulate the multi-layered structure of tissue; the arrangement, diameter, and orientation of fibers in each layer can be precisely controlled. Uniformly arranged microfibers (20-180 μm in diameter) are superimposed on orthogonal coarse fibers (200-600 μm in diameter). Since the size scale of cells (20 μm) is closer to that of microfibers than that of coarse fibers, cells easily adhere to the finer microfibers and maintain a high proliferation rate. In addition, cells cross the pores to form cell sheets and gradually migrate to the coarse fibers, covering the entire scaffold. Compared to traditional coarse fiber scaffolds, the composite microfiber scaffold combining coarse and fine fibers designed in this invention can provide a more favorable microenvironment for cell adhesion. Meanwhile, due to the diameter of the microfibers, current microfiber scaffolds generally lack good mechanical properties. In the composite microfiber scaffold combining coarse and fine fibers designed in this invention, the main coarse fiber scaffold provides certain mechanical properties, acting as a support to protect the internal and interlayer microfibers and prevent structural deformation or collapse of the microfiber scaffold. Thus, this FDM-based 3D-printed microfiber scaffold simultaneously provides a certain level of mechanical strength and a cellular microenvironment conducive to cell adhesion, improving upon the problems of poor cell adhesion environment in traditional coarse fiber scaffolds and low mechanical strength in ordinary microfiber scaffolds. Attached Figure Description

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

[0034] Appendix Figure 2 This is a SEM image showing the effect of microfibers on the 3D-printed composite microfiber scaffold in Example 1.

[0035] Appendix Figure 3 This is a SEM image showing the effect of microfibers on the 3D-printed composite microfiber scaffold in Example 2.

[0036] Appendix Figure 4 This is a SEM image showing the effect of microfibers on the 3D-printed composite microfiber scaffold in Example 3.

[0037] Appendix Figure 5 This is a SEM image showing the effect of microfibers on the 3D-printed composite microfiber scaffold in Example 4.

[0038] Appendix Figure 6 This is a SEM image showing the effect of microfibers on the 3D-printed composite microfiber scaffold in Example 5.

[0039] Appendix Figure 7 This is a SEM image showing the effect of microfibers on the 3D-printed composite microfiber scaffold in Example 6.

[0040] Appendix Figure 8 The image shows the TGA thermogravimetric analysis results of the mineralization effect of microfiber scaffolds with different surface treatments and different mineralization incubation times in Example 1.

[0041] Appendix Figure 9 The figure shows the results of the mechanical tensile properties of microfiber scaffolds with different surface treatments and mineralized microfiber scaffolds in Example 1. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the example figures. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0043] To achieve the aforementioned objective of fabricating 3D-printed microfiber scaffolds, the fabrication scheme employed in this invention is as follows:

[0044] Example 1

[0045] The following is a method for fabricating 3D-printed microfiber scaffolds:

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

[0047] The microfiber scaffold model was designed through modeling and the path was set using G-code; including:

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

[0049] S12. Slice the model: Import the 3D fiber scaffold model created in S11 into 3D printing slicing software (such as Ultimaker Cura), set the initial printing parameters, and slice the printed model.

[0050] S13. Write G-code for the slicing program: Find the area code that needs to be printed with microfibers in the G-code obtained after slicing. Set the printing nozzle temperature to 235℃ and the nozzle idle speed to 9000mm / min through the G-code to obtain microfibers with a diameter of 20μm.

[0051] S2. Microfiber scaffold printing scaffold

[0052] S21. Printing of the main body of the bracket: The main body of the bracket is printed by directly running the G-code obtained through the slicing program using an FDM printer;

[0053] S22. Microfiber preparation: Under the control of G-code, the nozzle pauses extrusion after printing to one end of the main support. The nozzle does not perform a retraction operation. Then, the nozzle moves quickly according to the preset microfiber printing path, runs empty to the other end of the main support corresponding to the microfiber, stretches the material deposited by the printing nozzle to a suitable position, and then the nozzle continues printing to achieve microfiber preparation.

[0054] S23. Fabrication of microfiber scaffolds: The structure is formed by printing microfibers one layer at a time in G-code, with the microfiber orientation between layers at 90°, thus forming an orthogonal multilayer microfiber scaffold.

[0055] Example 2

[0056] The difference from Example 1 is that:

[0057] In step S13, the printing nozzle temperature is set to 235℃ and the nozzle idle speed is set to 7000mm / min by using G-code, which can obtain microfibers with a diameter of 60μm.

[0058] Everything else is the same as in Example 1.

[0059] Example 3

[0060] The difference from Example 1 is that:

[0061] In step S13, the printing nozzle temperature is set to 235℃ and the nozzle idle speed is set to 6000mm / min by using G-code, which can obtain microfibers with a diameter of 80μm.

[0062] In step S3, the microfiber scaffolds printed in S23 are 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 printing nozzle temperature is set to 240℃ and the nozzle idle speed is set to 7000mm / min by using G-code, which can obtain microfibers with a diameter of 100μm.

[0066] Everything else is the same as in Example 1.

[0067] Example 5

[0068] The difference from Example 1 is that:

[0069] In step S13, the printing nozzle temperature is set to 230℃ and the nozzle idle speed is set to 8000mm / min by using G-code, which can obtain microfibers with a diameter of 120μm.

[0070] Everything else is the same as in Example 1.

[0071] Example 6

[0072] The difference from Example 1 is that:

[0073] In step S13, the printing nozzle temperature is set to 230℃ and the nozzle idle speed is set to 6000mm / min by using G-code, which can obtain microfibers with a diameter of 150μm.

[0074] Everything else is the same as in Example 1.

[0075] Example 7

[0076] The difference from Example 1 is that:

[0077] In step S13, the printing nozzle temperature is set to 230℃ and the nozzle idle speed is set to 5000mm / min by using G-code, which can obtain microfibers with a diameter of 180μm.

[0078] Everything else is the same as in Example 1.

Claims

1. A method for preparing a 3D-printed composite microfiber scaffold, characterized in that, The microfiber scaffold preparation method comprises: S1. Construction of microfiber scaffold model and path setting: The microfiber scaffold model is designed by modeling and the path is set by G-code code; the specific operation steps comprise: S11. 3D modeling of fiber scaffold; S12. Slicing the model: import the 3D fiber scaffold model modeled in S11 into the 3D printing slicing software, perform preliminary setting of printing parameters, and slice the printing model; S13. G-code code writing for slicing program: find the area code that needs to be printed with microfibers 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 lengths, interval distances, thickness levels, and arrangement modes; S2. Microfiber scaffold printing scaffold S21. Scaffold main body printing: directly use the FDM printer to run the G-code code obtained through the slicing program to print the scaffold main body; S22. Preparation of microfibers: the nozzle pauses extrusion after the main scaffold is printed to an endpoint under the control of the G-code code, the nozzle does not perform a back-pulling operation, then the nozzle moves quickly according to the preset microfiber printing path, and the nozzle moves to the other endpoint corresponding to the microfiber on the main scaffold, after the material deposited by the printing nozzle is stretched to the preset position, the nozzle continues to print, realizing the preparation of microfibers, and the microfiber diameter ranges from 20 to 180 μm; S23. Preparation of microfiber scaffold: print the microfibers once in the G-code code for each layer, and the microfiber direction between layers is 90°, thereby forming a multi-layer microfiber scaffold with an orthogonal structure.

2. The method of claim 1, wherein the 3D printed composite microfiber scaffold is prepared by the steps of: In S13, the printing nozzle temperature is 235-245℃, and the printing speed is 6000-9000 mm / min.

3. The 3D printed composite microfiber scaffold prepared according to the method of claim 1, wherein, The scaffold comprises a mineralized microfiber scaffold composed of pure microfibers inside and a composite fiber scaffold composed of a peripheral scaffold constructed by thick fibers.

4. The 3D printed composite microfiber scaffold prepared according to the method of claim 1, wherein, The scaffold is made of one or two thermoplastic polymer materials selected from polylactic acid, polycaprolactone, and polyether ether ketone.

5. The 3D printed composite micro-fiber scaffold prepared by the method of claim 1, wherein, The microfiber diameter in the scaffold is 20-100 μm.

6. The 3D printed composite microfiber scaffold prepared by the method of claim 1, wherein, The microfiber diameter in the scaffold is 20-60 μm.

Images