3D printing preparation method of silver-loaded multi-walled carbon nanotube and PEG modified polylactic acid composite bone scaffold with synergistic antibacterial function of biodegradation, photothermal effect and ion release

Abstract

The invention discloses a 3D printing preparation method of a silver-loaded multi-walled carbon nanotube and PEG modified polylactic acid composite bone scaffold with a synergistic antibacterial function of biodegradation, photothermal effect and ion release. The method comprises the following steps: (1) preparing a silver-loaded multi-walled carbon nanotube (MWCNT (at) Ag) by adopting an impregnation reduction method; and (2) mixing polylactic acid (PLA), polyethylene glycol (PEG) and MWCNT (at) Ag, preparing a composite film by a solvent casting method, preparing a composite wire by a single screw extruder, and finally preparing the bone scaffold by a fused deposition modeling (FDM) 3D printing technology. PEG can improve biodegradability of the stent, MWCNT can generate a photothermal effect under irradiation of near-infrared light (NIR), the stent is endowed with a photothermal treatment function, meanwhile, the MWCNT can effectively load AgNPs, slow release of silver ions is achieved through a unique tubular structure of the MWCNT, and the antibacterial performance is remarkably improved. The scaffold integrates controllable degradation, photo-thermal antibiosis and excellent mechanical properties, is suitable for bone defect repair and infectious bone defect treatment, and has important application value in the field of bone tissue engineering.

Description

Technical Field

[0001] The present invention belongs to the field of medical materials for bone injury repair, and particularly relates to a 3D printing preparation method of a silver-loaded multi-walled carbon nanotube and PEG-modified polylactic acid composite bone scaffold with synergistic antibacterial functions of biodegradation, photothermal effect and ion release. By introducing polyethylene glycol (PEG), multi-walled carbon nanotubes (MWCNT) and silver nanoparticles (AgNPs), the scaffold is endowed with good biodegradability, photothermal effect and antibacterial properties, and is suitable for the repair of bone defects and the treatment of infectious bone defects. Background Art

[0002] Bone defect problems caused by accidental injuries, bone tumors, osteoporosis and other factors are very common in clinical practice. However, current bone implants usually only play a temporary replacement role and are difficult to effectively promote the regeneration and repair of defective bone tissue. Therefore, the design and preparation of artificial bone scaffolds have become an important research direction for solving bone defect problems. An ideal bone scaffold not only needs to provide necessary mechanical support, but also should have good biocompatibility and controllable degradation performance to promote the formation of new bone tissue. In addition, during the bone repair process, bacterial infection is a common risk, which may lead to infectious bone defects, thereby causing the lesions and failure of implants. At present, antibiotic treatment is still the main anti-infection means in clinical practice, but it has limitations such as wide drug diffusion, large toxic and side effects, low utilization efficiency and short half-life. Therefore, how to construct a bone scaffold with antibacterial function and capable of promoting bone regeneration has become the key research direction at present.

[0003] Polylactic acid (PLA) has been widely used in the field of bone tissue engineering due to its excellent biocompatibility, degradability and good processing properties. However, the mechanical properties of PLA are weak, the degradation rate is difficult to control, and there is a certain risk of bacterial infection, which limits its application as a bone scaffold material. To improve the applicability of PLA, it is particularly important to conduct modification research on it. Common modification methods include polymer blending and nano-filler reinforcement.

[0004] In terms of polymer blending, polyethylene glycol (PEG), as a polymer material with good biodegradability and strong thermal stability, can effectively improve the degradation rate of PLA when compounded with PLA, making it more suitable for bone tissue engineering. At the same time, PEG can be degraded into carbon dioxide and water by microorganisms in the natural environment, further enhancing the environmental protection of the material.

[0005] In terms of nano-filler reinforcement modification, due to their unique physical and chemical properties, nano-materials exhibit great application potential in the biomedical field. Some nano-materials can produce a photothermal effect under near-infrared light (NIR) irradiation, enabling precise local hyperthermia. In addition, optimizing the microstructure and composition of the material can achieve the controlled release of functional molecules, further enhancing the antibacterial properties of the material. Multi-walled carbon nanotubes (MWCNT) can effectively enhance the mechanical properties of bone scaffolds due to their excellent mechanical properties and ultra-high specific surface area, and produce a photothermal effect under NIR irradiation, endowing the scaffold with photothermal therapy function.

[0006] Silver nanoparticles (AgNPs) have become important materials for bone scaffold functionalization due to their broad-spectrum antibacterial properties. MWCNT can effectively load AgNPs and achieve the slow release of silver ions through its unique tubular structure, significantly enhancing the antibacterial performance. Summary of the Invention

[0007] Aiming at the problems of slow degradation rate, insufficient mechanical properties and lack of antibacterial function in existing polylactic acid (PLA) bone scaffolds, the present invention provides a preparation method of a 3D-printed polylactic acid composite bone scaffold with biodegradation, photothermal effect and ion release synergistic antibacterial properties. By introducing polyethylene glycol (PEG), multi-walled carbon nanotubes (MWCNT) and silver nanoparticles (AgNPs), the present invention endows the scaffold with excellent biodegradability, photothermal effect and antibacterial properties. Specifically, the present invention uses fused deposition modeling (FDM) 3D printing technology to print PLA, PEG and silver-loaded multi-walled carbon nanotube (MWCNT@Ag) composite materials into bone scaffolds. Multi-walled carbon nanotubes (MWCNT) as a carrier can effectively load silver nanoparticles (AgNPs) and achieve the slow release of silver ions through its unique tubular structure, thereby endowing the scaffold with a long-term antibacterial function. Under near-infrared light (NIR) irradiation, multi-walled carbon nanotubes (MWCNT) can produce a photothermal effect, causing a local temperature increase, effectively inhibiting the growth of bacteria and tumor cells. The introduction of polyethylene glycol (PEG) significantly improves the biodegradability of the scaffold, making it more suitable for bone tissue engineering. The 3D-printed polylactic acid composite bone scaffold provided by the present invention has biodegradability, photothermal effect and antibacterial properties, and is suitable for the repair of bone defects and the treatment of infectious bone defects, with broad application prospects.

[0008] To achieve the above technical objectives, the present invention adopts the following technical solutions.

[0009] A 3D printing preparation method of a silver-loaded multi-walled carbon nanotube and PEG-modified polylactic acid composite bone scaffold with biodegradation, photothermal effect and ion release synergistic antibacterial functions, comprising the following steps:

[0010] 1) Generate silver-loaded multi-walled carbon nanotubes by the impregnation reduction method.

[0011] 2) Prepare the PLA / PEG / MWCNT@Ag composite film by the solvent casting method.

[0012] 3) Prepare the PLA / PEG / MWCNT@Ag composite filament from the composite film obtained in step 2) by a single-screw extruder.

[0013] 4) Prepare the 3D-printed PLA / PEG / MWCNT@Ag composite scaffold from the composite filament obtained in step 3) by means of fused deposition modeling (FDM) 3D printing.

[0014] In a preferred embodiment, the inner diameter of the multi-walled carbon nanotubes is 3 - 5 nm, the outer diameter is 8 - 15 nm, the length is 5 - 15 μm, and the purity is not less than 98%.

[0015] In a preferred embodiment, in the method of the present invention, the silver-loaded multi-walled carbon nanotubes are generated by the impregnation reduction method in step 1): 3 g of multi-walled carbon nanotubes are ultrasonically dispersed in 300 mL of deionized water for 30 min to obtain a multi-walled carbon nanotube dispersion; 1.6 g of silver nitrate is added to 100 mL of deionized water and magnetically stirred at 60 °C for 30 min to obtain a silver nitrate solution; the silver nitrate solution is added to the multi-walled carbon nanotube dispersion, ultrasonically dispersed for 30 min, and then 1.2 g of ascorbic acid is added and magnetically stirred at 60 °C for 3 h; the silver-loaded multi-walled carbon nanotubes precipitate is obtained by centrifugal separation at a centrifugal speed of 5000 revolutions per minute and a centrifugation time of 5 min, and the centrifugation, washing, and resuspension processes are repeated 3 times with absolute ethanol and then dried in vacuo to obtain silver-loaded multi-walled carbon nanotubes (MWCNT@Ag).

[0016] In a preferred embodiment, in the method of the present invention, the PLA / PEG / MWCNT@Ag composite film is prepared by the solvent casting method in step 2): 85 wt% - 97.5 wt% of PLA is dissolved in dichloromethane and stirred with a magnetic stirrer at 40 °C for 1 h to obtain a PLA solution. 2.5 wt% - 15 wt% of PEG is dissolved in the PLA solution. Then it is stirred with a magnetic stirrer at 40 °C for 1 h to obtain a PLA / PEG mixed solution. 2 wt% - 6 wt% of the MWCNT@Ag powder in the PLA / PEG / MWCNT@Ag mixed solution is ultrasonically dispersed in dichloromethane for 30 min and then added to the PLA-PEG mixed solution, and stirred with a magnetic stirrer at 40 °C for 2 - 3 h to obtain a PLA / PEG / MWCNT@Ag mixed solution. The mixed solution is placed in a tray and dried at room temperature for 12 h to volatilize the solvent, obtaining the PLA / PEG / MWCNT@Ag composite film.

[0017] In a preferred embodiment, the molecular weight of the PEG is 1000.

[0018] In a preferred embodiment, the inventors found that when the PEG content is too low, the degradation rate of the bone scaffold is not significantly promoted, while when the PEG content is too high, the mechanical properties of the bone scaffold will be reduced.

[0019] In a preferred embodiment, the inventors found that when the MWCNT@Ag content is too low, the antibacterial property of the bone scaffold is not significantly promoted, and when the MWCNT@Ag content is too high, the biological properties of the bone scaffold will be reduced.

[0020] In a preferred embodiment, in the method of the present invention, in step 3), the PLA / PEG / MWCNT@Ag composite filament is prepared by a single-screw extruder: the PLA / PEG / MWCNT@Ag composite film is dried and cut into sheet materials, and dried in an environment of 50 °C for 12 - 24 hours. The dried sheet materials are used to prepare composite filaments for fused deposition modeling (FDM) 3D printing by a single-screw extruder. The extrusion section temperature of the single-screw extruder is set at 165 - 170 °C, and the plasticizing section temperature is 170 - 180 °C. Filaments with an average filament diameter of 1.65 - 1.85 mm are obtained by controlling the extrusion speed and the traction speed.

[0021] In a preferred embodiment, in the method of the present invention, in step 4), the 3D printed PLA / PEG / MWCNT@Ag composite scaffold is prepared by the method of fused deposition modeling (FDM) 3D printing: The key parameters of the FDM technology include: nozzle size 0.2 - 0.4 mm, layer height 0.1 - 0.2 mm, printing speed 20 - 40 mm / s, extrusion temperature 180 - 210 °C, printing platform temperature 40 - 60 °C, and a filling rate of 100%.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] By introducing polyethylene glycol (PEG), the degradation rate of the polylactic acid (PLA) scaffold is significantly increased, making it more in line with the requirements of bone tissue engineering.

[0024] Multi-walled carbon nanotubes (MWCNT) produce a photothermal effect under near-infrared light (NIR) irradiation, endowing the scaffold with a photothermal therapy function. This function can effectively inhibit bacterial growth and provide a new solution for the repair of bone defects and the treatment of infectious bone defects.

[0025] Multi-walled carbon nanotubes (MWCNT) as a carrier can effectively load AgNPs and achieve the slow release of silver ions through its unique tubular structure, thereby significantly enhancing the anti-infection ability of the scaffold and effectively preventing and treating bacterial infections during the repair of bone defects.

[0026] The introduction of multi-walled carbon nanotubes (MWCNT) significantly enhances the mechanical properties of the scaffold, improves the tensile strength and compressive strength of the scaffold, and makes it more suitable for the repair of bone defects.

[0027] By combining the FDM 3D printing technology and the solvent casting method, the preparation process is simple and easy for large-scale production. This process can not only precisely control the pore structure and mechanical properties of the scaffold, but also achieve personalized customization of complex shapes to meet the clinical needs of different patients. Description of the Drawings

[0028] Figure 1 Scaffold morphologies of Example 1 and Comparative Examples 1-3.

[0029] Figure 2 Tensile strengths of Example 1 and Comparative Examples 1-3.

[0030] Figure 3 Compressive strengths of Example 1 and Comparative Examples 1-3.

[0031] Figure 4 Mass loss of the bone scaffolds prepared in Example 1 and Comparative Examples 1-3 after 7 days of degradation.

[0032] Figure 5 Photothermal effects of the bone scaffolds prepared in Example 1 and Comparative Examples 1-3. Figure 6 Survival of Escherichia coli in the bone scaffolds prepared in Example 1 and Comparative Examples 1-3 with and without near-infrared light irradiation. Detailed Description of the Invention

[0034] The following further describes the specific embodiments of the present invention in conjunction with specific examples, but the content of the present invention is not limited thereto.

[0035] Example 1

[0036] 1) Ultrasonically disperse 3 g of multi-walled carbon nanotubes in 300 mL of deionized water for 30 min to obtain a multi-walled carbon nanotube dispersion; add 1.6 g of silver nitrate to 100 mL of deionized water and magnetically stir at 60 °C for 30 min to obtain a silver nitrate solution; add the silver nitrate solution to the multi-walled carbon nanotube dispersion, ultrasonically disperse for 30 min, then add 1.2 g of ascorbic acid and magnetically stir at 60 °C for 3 h; centrifuge and separate at a centrifugation speed of 5000 revolutions per minute and a centrifugation time of 5 min to obtain a silver-loaded multi-walled carbon nanotube precipitate. Repeat the centrifugation, washing, and resuspension processes 3 times with absolute ethanol and then vacuum dry to obtain silver-loaded multi-walled carbon nanotubes (MWCNT@Ag).

[0037] 2) Dissolve 54 g of polylactic acid (PLA) in dichloromethane (DCM), and stir for 1 hour at 40 °C using a magnetic stirrer to obtain a PLA solution. Dissolve 6 g of polyethylene glycol (PEG) in the PLA solution, and stir for 1 hour at 40 °C using a magnetic stirrer to obtain a PLA / PEG mixed solution. Ultrasonically disperse 3.15 g of MWCNT@Ag obtained in step 1 in dichloromethane (DCM) for 30 min, then add it to the PLA / PEG mixed solution, and then stir for 2 - 3 hours at 40 °C using a magnetic stirrer to obtain a PLA / PEG / MWCNT@Ag mixed solution. Place the mixed solution in a tray and dry it at room temperature for 12 hours to allow the solvent to evaporate, obtaining a PLA / PEG / MWCNT@Ag composite film.

[0038] 3) Cut the composite film prepared in step 2 into small pieces, and use a single-screw extruder to produce PLA / PEG / MWCNT@Ag filaments. The set parameters of the single-screw extruder are as follows: the temperature of the extrusion section is set at 175 °C, and the temperature of the plasticizing section is 180 °C. The average filament diameter of the produced PLA / PEG / MWCNT@Ag is 1.75 mm.

[0039] 4) Use CAD software to design a porous structure scaffold with a size of 10×10×10 mm, a pore diameter of 0.8 mm, a rod diameter of 0.8 mm, and a porosity of 50%, and export it in STL format. Slice the STL file and import it into an FDM printer to prepare a PLA / PEG / MWCNT@Ag composite scaffold. The key parameters of the FDM technology include a nozzle size of 0.4 mm, a layer height of 0.2 mm, a printing speed of 20 mm / s, an extrusion temperature of 200 °C, a printing platform temperature of 40 °C, and a filling rate of 100%.

[0040] Observation of the scaffold morphology found that the surface color of the PLA / PEG / MWCNT@Ag composite scaffold changed from the original white to black, and the surface of the scaffold became rough from smooth.

[0041] Through mechanical property test experiments, it was found that the tensile strength of the PLA / PEG / MWCNT@Ag composite scaffold was 70 MPa, and the compressive strength was 19 MPa.

[0042] Through degradation property test experiments, it was found that the mass loss of the PLA / PEG / MWCNT@Ag composite scaffold in a PBS solution containing 0.3 mg / mL after 7 days of degradation was 13.55%.

[0043] Through the photothermal performance test experiment, it was found that the PLA / PEG / MWCNT@Ag composite scaffold could rapidly heat up to 53.7°C under the irradiation of 808 nm near-infrared light with an intensity of 0.2 w / cm² for 60 s, and basically stabilized at 60.6°C under the irradiation for 5 min. In PBS solution, the PLA / PEG / MWCNT@Ag composite scaffold could heat up to 46.1°C under the irradiation of 808 nm near-infrared light with an intensity of 0.6 w / cm² for 60 s, and basically stabilized at 52.1°C under the irradiation for 5 min. It showed strong photothermal performance.

[0044] Through the antibacterial performance test experiment, it was found that the survival rate of Escherichia coli on the PLA / PEG / MWCNT@Ag composite scaffold without 808 nm near-infrared light irradiation was 24.08%, and the survival rate of Escherichia coli on the PLA / PEG / MWCNT@Ag composite scaffold after 808 nm near-infrared light irradiation was 6.83%.

[0045] Comparative Example 1

[0046] 1) Dissolve 60 g of polylactic acid (PLA) in dichloromethane (DCM), and stir with a magnetic stirrer at 40°C for 1 hour to obtain a PLA solution. Place the PLA solution in a tray and dry it at room temperature for 12 hours to volatilize the solvent and obtain a PLA film.

[0047] 2) Cut the PLA film prepared in step 1 into small pieces, and use a single-screw extruder to produce PLA filaments. The set parameters of the single-screw extruder are: the temperature of the extrusion section is set to 175°C, and the temperature of the plasticizing section is 180°C. The average filament diameter of the produced PLA is 1.75 mm.

[0048] 3) Use CAD software to design a porous structure scaffold with a size of 10×10×10 mm, a pore diameter of 0.8 mm, a rod diameter of 0.8 mm, and a porosity of 50%, and export it in STL format. Slice the STL file and import it into an FDM printer to prepare a PLA composite scaffold. The key parameters of the FDM technology include a nozzle size of 0.4 mm, a layer height of 0.2 mm, a printing speed of 20 mm / s, an extrusion temperature of 200°C, a printing platform temperature of 40°C, and a filling rate of 100%.

[0049] Through the observation of the scaffold morphology, it was found that the PLA scaffold was colorless and transparent, and the surface of the scaffold was smooth.

[0050] Through the mechanical performance test experiment, it was found that the tensile strength of the PLA scaffold was 62.27 MPa, and the compressive strength was 15.07 MPa.

[0051] Through the degradation performance test experiment, it was found that the mass loss of the PLA composite scaffold in PBS solution containing 0.3 mg / mL after 7 days of degradation was 9.89%.

[0052] Through the photothermal performance test experiment, it was found that the temperature of the PLA scaffold hardly changed under the irradiation of 808 nm near-infrared light at 0.2 w / cm², which confirmed that it did not have photothermal performance.

[0053] Through the antibacterial performance test experiment, it was found that the survival rate of Escherichia coli on the PLA scaffold without 808 nm near-infrared light irradiation was 105.74%, and the antibacterial rate of the PLA scaffold after 808 nm near-infrared light irradiation against Escherichia coli was 106.52%.

[0054] Comparative Example 2

[0055] 1) Dissolve 54 g of polylactic acid (PLA) in dichloromethane (DCM), and stir with a magnetic stirrer at 40 °C for 1 hour to obtain a PLA solution. Dissolve 6 g of polyethylene glycol (PEG) in the PLA solution, and stir with a magnetic stirrer at 40 °C for 1 hour to obtain a PLA / PEG composite solution. Place the PLA / PEG solution in a tray and dry it at room temperature for 12 hours to volatilize the solvent and obtain a PLA / PEG composite film.

[0056] 2) Cut the composite film prepared in step 1 into small pieces and use a single-screw extruder to produce PLA / PEG filaments. The set parameters of the single-screw extruder are: the temperature of the extrusion section is set to 175 °C, and the temperature of the plasticizing section is 180 °C. The average filament diameter of the produced PLA / PEG is 1.75 mm.

[0057] 3) Use CAD software to design a porous structure scaffold with a size of 10×10×10 mm, a pore diameter of 0.8 mm, a rod diameter of 0.8 mm, and a porosity of 50%, and export it in STL format. Slice the STL file and import it into an FDM printer to prepare a PLA / PEG composite scaffold. The key parameters of the FDM technology include a nozzle size of 0.4 mm, a layer height of 0.2 mm, a printing speed of 20 mm / s, an extrusion temperature of 200 °C, a printing platform temperature of 40 °C, and a filling rate of 100%.

[0058] Through the observation of the scaffold morphology, it was found that the surface color of the PLA / PEG composite scaffold was colorless and transparent, and the surface of the scaffold was smooth.

[0059] Through the mechanical performance test experiment, it was found that the tensile strength of the PLA / PEG composite scaffold was 43.73 MPa, and the compressive strength was 10.35 MPa.

[0060] Through the degradation performance test experiment, it was found that the mass loss of the PLA / PEG composite scaffold in PBS solution containing 0.3 mg / mL after 7 days of degradation was 14.12%.

[0061] It was found through the photothermal performance test experiment that the temperature of the PLA / PEG scaffold hardly changed under the irradiation of 808 nm near-infrared light with a power density of 0.2 W / cm², which confirmed that it did not have photothermal performance.

[0062] It was found through the antibacterial performance test experiment that the survival rate of Escherichia coli on the PLA / PE composite scaffold without 808 nm near-infrared light irradiation was 111.58%, and the survival rate of Escherichia coli on the PLA / PEG / MWCNT@Ag composite scaffold after 808 nm near-infrared light irradiation was 112.61%.

[0063] Comparative Example 3

[0064] 1) Dissolve 54 g of polylactic acid (PLA) in dichloromethane (DCM), and stir with a magnetic stirrer at 40 °C for 1 hour to obtain a PLA solution. Dissolve 6 g of polyethylene glycol (PEG) in the PLA solution, and stir with a magnetic stirrer at 40 °C for 1 hour to obtain a PLA / PEG solution. Ultrasonically disperse 2.53 g of MWCNT@Ag obtained in step 1) in dichloromethane (DCM) for 30 min, then add it to the PLA / PEG mixed solution, and then stir with a magnetic stirrer at 40 °C for 2 - 3 hours to obtain a PLA / PEG / MWCNT mixed solution. Place the mixed solution in a tray and dry it at room temperature for 12 hours to volatilize the solvent and obtain a PLA / PEG / MWCNT composite film.

[0065] 2) Cut the composite film prepared in step 1) into small pieces, and use a single-screw extruder to produce PLA / PEH / MWCNT filaments. The set parameters of the single-screw extruder are: the temperature of the extrusion section is set to 175 °C, and the temperature of the plasticizing section is 180 °C. The average filament diameter of the produced PLA / PEG / MWCNT is 1.75 mm.

[0066] 3) Use CAD software to design a porous structure scaffold with a size of 10×10×10 mm, a pore diameter of 0.8 mm, a rod diameter of 0.8 mm, and a porosity of 50%, and export it in STL format. Slice the STL file and import it into an FDM printer to prepare a PLA / PEG / MWCN composite scaffold. The key parameters of the FDM technology include a nozzle size of 0.4 mm, a layer height of 0.2 mm, a printing speed of 20 mm / s, an extrusion temperature of 200 °C, a printing platform temperature of 40 °C, and a filling rate of 100%.

[0067] It was found through the observation of the scaffold morphology that the color of the PLA / PEG / MWCNT composite scaffold was black, and the surface of the scaffold was relatively rough.

[0068] It was found through the mechanical performance test experiment that the tensile strength of the PLA / PEG / MWCNT composite scaffold was 63.97 MPa, and the compressive strength was 18.09 MPa.

[0069] It was found through the degradation performance test experiment that the mass loss of the PLA / PEG / MWCNT composite scaffold was 14.73% after 7 days of degradation in a PBS solution containing 0.3 mg / mL.

[0070] It was found through the photothermal performance test experiment that the PLA / PEG / MWCNT composite scaffold could rapidly heat up to 48.4 °C under 60 s of irradiation with 808 nm near-infrared light at 0.2 w / cm², and basically stabilized at 54.8 °C under 5 min of irradiation, showing strong photothermal performance.

[0071] It was found through the antibacterial performance test experiment that the survival rate of Escherichia coli on the PLA / PEG / MWCNT composite scaffold without 808 nm near-infrared light irradiation was 84.55%, and the survival rate of Escherichia coli on the PLA / PEG / MWCNT@Ag composite scaffold after 808 nm near-infrared light irradiation was 71.41%.

Claims

1. A 3D printing preparation method of a composite bone scaffold of silver-loaded multi-walled carbon nanotubes and PEG-modified polylactic acid with biodegradation, photothermal effect and ion release synergistic antibacterial function, characterized in that: The following steps are involved: 1) Generation of silver-loaded multi-walled carbon nanotubes (MWCNT@Ag) by impregnation reduction method; 2) Preparation of PLA / PEG / MWCNT@Ag composite films by solvent casting method; 3) preparing the composite film obtained in step 2 into a PLA / PEG / MWCNT@Ag composite wire by a single screw extruder; 4) The composite filament obtained in step 3 was prepared into a 3D printed PLA / PEG / MWCNT@Ag composite scaffold using fused deposition modeling (FDM) 3D printing technology.

2. The 3D printing preparation method of the composite bone scaffold of silver-loaded multi-walled carbon nanotubes and PEG-modified polylactic acid with biodegradation, photothermal effect and ion release synergistic antibacterial function according to claim 1, characterized in that: In the step 1, multi-walled carbon nanotubes (MWCNT) are ultrasonically dispersed in deionized water, a silver nitrate solution and ascorbic acid are added, and silver-loaded multi-walled carbon nanotubes (MWCNT@Ag) are obtained by centrifugation, washing and drying.

3. The 3D printing preparation method of the composite bone scaffold of silver-loaded multi-walled carbon nanotubes and PEG-modified polylactic acid with biodegradation, photothermal effect and ion release synergistic antibacterial function according to claim 1, characterized in that: In the step 2, polylactic acid (PLA) is dissolved in dichloromethane, polyethylene glycol (PEG) and silver-loaded multi-walled carbon nanotubes (MWCNT@Ag) are added, and the mixture is stirred evenly and then dried to obtain a PLA / PEG / MWCNT@Ag composite film.

4. The 3D printing preparation method of the composite bone scaffold of silver-loaded multi-walled carbon nanotubes and PEG-modified polylactic acid with biodegradation, photothermal effect and ion release synergistic antibacterial function according to claim 1, characterized in that: In the step 3, the PLA / PEG / MWCNT@Ag composite film is cut into pieces and then used to prepare composite wires through a single screw extruder. The extrusion section temperature is 165-170° C., the plasticization section temperature is 170-180° C., and the average wire diameter of the wires is 1.65-1.85 mm.

5. The 3D printing preparation method of the composite bone scaffold of silver-loaded multi-walled carbon nanotubes and PEG-modified polylactic acid with biodegradation, photothermal effect and ion release synergistic antibacterial function according to claim 1, characterized in that: In step 4, the composite bracket is prepared by fused deposition modeling (FDM) 3D printing technology, and the key parameters include: nozzle size 0.2-0.4 mm, layer height 0.1-0.2 mm, printing speed 20-40 mm / s, extrusion temperature 180-210°C, printing platform temperature 40-60°C and 100% filling rate.

6. The 3D printing preparation method of the composite bone scaffold of silver-loaded multi-walled carbon nanotubes and PEG-modified polylactic acid with biodegradation, photothermal effect and ion release synergistic antibacterial function according to claim 1, characterized in that: The molecular weight of the polyethylene glycol (PEG) is 1000.

7. The 3D printing preparation method of the composite bone scaffold of silver-loaded multi-walled carbon nanotubes and PEG-modified polylactic acid with biodegradation, photothermal effect and ion release synergistic antibacterial function according to claim 1, characterized in that: The multi-walled carbon nanotube (MWCNT) has an inner diameter of 3-5 nm, an outer diameter of 8-15 nm, a length of 5-15 μm, and a purity of not less than 98%.

8. The 3D printing preparation method of the composite bone scaffold of silver-loaded multi-walled carbon nanotubes and PEG-modified polylactic acid with biodegradation, photothermal effect and ion release synergistic antibacterial function according to claim 1, characterized in that: The content of the silver-loaded multi-walled carbon nanotubes (MWCNT@Ag) is 2wt%-6wt%.

9. A 3D printing preparation method of a composite bone scaffold containing silver-loaded multi-walled carbon nanotubes and PEG-modified polylactic acid having synergistic antibacterial functions of biodegradation, photothermal effect and ion release according to any one of claims 1 to 8, characterized in that: The scaffold has biodegradability, photothermal effect and ion release synergistic antibacterial properties.

10. The 3D printing preparation method of the composite bone scaffold of silver-loaded multi-walled carbon nanotubes and PEG-modified polylactic acid with biodegradation, photothermal effect and ion release synergistic antibacterial function according to claim 9, characterized in that: The stent can produce a photothermal effect under near-infrared light (NIR) irradiation, the temperature can rise to 50-60°C, and can slowly release silver ions to achieve a long-lasting antibacterial effect.

Images