Antibacterial coating of MDI-based curable resin osteogenic scaffold and preparation method thereof

Abstract

This application belongs to the field of biomedical materials and tissue engineering technology, and discloses an antibacterial coating based on MDI-cured resin osteogenic scaffold and its preparation method. It innovatively uses diphenylmethane diisocyanate (MDI) as a curing crosslinking agent. With the help of its excellent reactivity and chemical properties, a variety of antibacterial agents (including tannic acid, ornidazole and minocycline hydrochloride) are firmly bound to the surface of a 3D printed blank resin scaffold, and a coating with hydrophilicity, high efficiency antibacterial properties and low cytotoxicity is successfully constructed, which has good antibacterial effect against both Gram-positive and Gram-negative bacteria.

Description

Technical Field

[0001] This application belongs to the field of biomedical materials and tissue engineering technology, and relates to the surface antibacterial functionalization and antibacterial coating construction of 3D printed resin osteogenic scaffolds, specifically to an antibacterial coating based on MDI-cured resin osteogenic scaffold and its preparation method. Background Technology

[0002] 3D printing technology has matured in the field of bone repair scaffold fabrication, offering advantages such as rapid curing, high designability, high forming precision, and adjustable mechanical properties, making it particularly suitable for precision manufacturing for individual patients. Utilizing computer-aided design (CAD) and computed tomography (CT) data, 3D printing can construct personalized scaffolds that highly match the anatomical morphology of the defect site, achieving precise control over porosity, pore size, and pore connectivity, gradually becoming an important technological pathway for bone tissue engineering scaffold fabrication. Furthermore, this technology exhibits good compatibility with various material systems, allowing the processing of diverse biomaterials, including synthetic polymers (such as polylactic acid and polycaprolactone), bioceramics (such as hydroxyapatite and β-tricalcium phosphate), and metallic materials (such as titanium alloys and magnesium alloys). Studies have reported that 3D-printed ceramic scaffolds with biomimetic pore structures can promote cell infiltration and angiogenesis, achieving effective repair in animal skull defect models. In addition, 3D-printed ultra-high molecular weight polyethylene skull patches customized based on patient CT data have been used in complex cases, achieving anatomical reduction and functional restoration. While 3D-printed scaffolds offer significant advantages in personalization and structural control, current technologies still face several key challenges, with postoperative infection risk being particularly prominent, especially in cases involving the repair of large bone defects. Related studies have shown that pathogens can significantly disrupt the local tissue microenvironment and weaken bone regeneration capacity, leading to local microcirculatory disturbances and consequently adverse outcomes such as osteonecrosis. Simultaneously, systemic antibiotic administration often fails to achieve effective drug concentrations at the infection site, potentially causing delayed bone healing, nonunion, and even serious consequences such as amputation.

[0003] With the integration of multiple disciplines, surface coating technology, originally widely used in industrial fields, is gradually entering the research field of medical materials. In recent years, researchers have developed bio-coating materials with multiple functions such as antibacterial, anticoagulant, and anti-inflammatory properties to meet different clinical needs. Therefore, constructing functional coatings on the surface of medical materials is considered an effective strategy to enhance the anti-infection ability of osteogenic scaffolds. For 3D-printed photocurable resin osteogenic scaffolds, in order to improve their biocompatibility and osteogenic performance, studies have shown that bioactive components can be introduced through surface coating technology; combining antibiotics and other drugs with photocurable resin systems to construct drug delivery systems is expected to enable the scaffold to simultaneously exert osteogenic and antibacterial effects during bone defect repair, thereby improving the repair effect. Diphenylmethane diisocyanate (MDI) is widely used in industrial fields as a curing agent, mainly due to its high reactivity and good chemical properties. In some medical materials, MDI can be used as a curing / crosslinking component to improve the mechanical properties and stability of the materials, and has been applied in the preparation of artificial joints and medical devices. In the field of dental materials, the application of MDI is mainly focused on its use as a raw material for polyurethane materials in the manufacture of dental polymer materials, while research and application in the surface functionalization of synthetic resin-based osteogenic scaffolds are relatively limited. Although some studies have attempted to directly incorporate antibacterial components into resin osteogenic scaffolds, the material degradation characteristics and drug release behavior have limited their long-term effects to some extent. In contrast, achieving interfacial enrichment and fixation of antibacterial components through surface coating may provide a more feasible approach to solving the above problems, but there are currently no relevant publications or patents. Summary of the Invention

[0004] The purpose of this application is to solve the problems of the prior art and provide an antibacterial coating for an MDI-cured resin osteogenic scaffold and its preparation method.

[0005] To solve the technical problem, the technical solution of this application is: a method for preparing an antibacterial coating for an MDI-cured resin osteogenic scaffold, comprising the following steps: Step 1: Using polyethylene glycol diacrylate and 3,3-dimethicone as the resin matrix, add diluent, and mix with photoinitiator and dispersant. Stir to uniformly disperse the components to obtain a photocurable resin slurry; wherein the weight ratio of polyethylene glycol diacrylate, 3,3-dimethicone, diluent, photoinitiator and dispersant is 12~16:26~30:5~9:0.1~0.5:0.1~0.5; Step 2: Use CAD software and slicing software to generate printing files for the resin support to be printed; Step 3: Pour the photocurable resin slurry into the polymer material tank, then import the printing file into the digital light processing 3D printing equipment to create a blank resin support. Step 4: Immerse the blank resin scaffold in a diphenylmethane diisocyanate solution for surface modification to obtain the modified resin scaffold. Step 5: Dissolve the antibacterial agent in N,N-dimethylformamide to prepare an antibacterial coating solution. The antibacterial agent is a polyphenolic antibacterial agent, a nitroimidazole antibacterial agent, or a tetracycline antibacterial agent. The weight ratio of the antibacterial agent to N,N-dimethylformamide is 0.075~1:1. Step 6: Immerse the modified resin scaffold in an antibacterial coating solution and cure it in an oven at 45~60℃ to obtain a resin scaffold with an antibacterial coating grafted on its surface.

[0006] Preferably, in step 1, the number average molecular weight of polyethylene glycol diacrylate is 1000, the purity of 3,3-dimethacrylic acid is ≥97%, the diluent is polypropylene glycol, the photoinitiator is 2,4,6-trimethylbenzoyl diphenylphosphine oxide, and the dispersant is DCA-1228.

[0007] Preferably, in step 1, the weight ratio of polyethylene glycol diacrylate, 3,3-dimethicone, diluent, photoinitiator and dispersant is 14:28:7:0.3:0.5.

[0008] Preferably, step 2 specifically involves: designing a three-dimensional model of the resin support to be printed in CAD software, exporting it as an STL file, importing the STL file into slicing software, setting printing parameters, and generating a printing file.

[0009] Preferably, step 3 specifically involves: pouring the photocurable resin slurry into the polymer material tank, importing the printing file into the digital light processing 3D printing equipment, curing it layer by layer with ultraviolet light until printing is complete, removing the printed part from the platform after printing, cleaning the printed part in isopropanol to remove uncured resin, and then curing it again under ultraviolet light to ensure that the resin is completely polymerized, thus obtaining a blank resin scaffold.

[0010] Preferably, the surface modification time in step 4 is 20~24h.

[0011] Preferably, in step 5: the polyphenolic antibacterial agent is tannic acid, the nitroimidazole antibacterial agent is ornidazole, and the tetracycline antibacterial agent is minocycline hydrochloride.

[0012] Preferably, the weight ratio of tannic acid to N,N-dimethylformamide is 0.16:1, the weight ratio of ornidazole to N,N-dimethylformamide is 1:1, and the weight ratio of minocycline hydrochloride to N,N-dimethylformamide is 0.075:1.

[0013] Preferably, step 6 specifically involves: immersing the modified resin scaffold in an antibacterial coating solution and curing it in an oven at 45-60°C for 0.5-1.5 hours; then washing the scaffold alternately with anhydrous ethanol and distilled water to remove residual solution from the surface; and finally air-drying it to obtain a resin scaffold with an antibacterial coating grafted onto its surface.

[0014] Preferably, an antibacterial coating based on an MDI-cured resin osteogenic scaffold is provided, wherein the antibacterial coating is prepared by the aforementioned method for preparing an MDI-cured resin osteogenic scaffold antibacterial coating.

[0015] Compared with the prior art, the advantages of this application are: (1) This application innovatively utilizes diphenylmethane diisocyanate (MDI) as a curing crosslinking agent. With the help of its excellent reactivity and chemical properties, a variety of antibacterial agents (including tannic acid, ornidazole and minocycline hydrochloride) are firmly bound to the surface of a 3D printed blank resin scaffold, and a coating with hydrophilic, highly efficient antibacterial properties and low cytotoxicity is successfully constructed, which has a good antibacterial effect on both Gram-positive and Gram-negative bacteria. (2) In this application, when modifying the surface of blank resin scaffold, the scaffold is first immersed in MDI solution and then immersed in antibacterial coating solution to complete the surface modification of the scaffold and covalent binding with antibiotics. The operation method is simple and reliable, which greatly reduces the technical sensitivity of constructing functional coatings. (3) Compared with existing scaffolds that load antibacterial drugs only through physical adsorption or simple impregnation, this application constructs an antibacterial layer through surface curing reaction, which can improve the fixation stability and coating continuity of antibacterial components on the scaffold surface, while not significantly damaging the original morphology and structure of the scaffold, thereby obtaining an osteogenic scaffold that has both antibacterial and biocompatibility. Attached Figure Description

[0016] Figure 1 This is a flowchart of a method for preparing an antibacterial coating for an MDI-cured resin osteogenic scaffold according to this application; Figure 2 This is a schematic diagram illustrating the preparation method of an antibacterial coating for an osteogenic scaffold based on MDI-cured resin according to this application. Figure 3 These are images showing the Staphylococcus aureus coating results of each group of scaffolds in Example 1 of this application; Figure 4 These are images showing the E. coli coating results of each group of scaffolds in Example 1 of this application; Figure 5 These are laser confocal microscopy results (Staphylococcus aureus) of each group of scaffolds in Example 2 of this application. Figure 6These are laser confocal microscopy results (E. coli) of each group of scaffolds in Example 2 of this application. Figure 7 This is an SEM image of Staphylococcus aureus on the scaffold in group ae in Example 3 of this application; Figure 8 This is an SEM image of Escherichia coli on the scaffold in the ae group of the third application example of this application. Detailed Implementation

[0017] The present application is described in detail below with reference to the accompanying drawings and specific embodiments, but the present application is not limited to these embodiments. The present application covers any alternatives, modifications, equivalent methods, and solutions made within the spirit and scope of the present application. To provide the public with a thorough understanding of the present application, specific details are described in detail in the following embodiments, but those skilled in the art will fully understand the present application even without these detailed descriptions.

[0018] like Figure 1 As shown, this application discloses a method for preparing an antibacterial coating based on an MDI-cured resin osteogenic scaffold, comprising the following steps: Step 1: Using polyethylene glycol diacrylate and 3,3-dimethicone as the resin matrix, add diluent, and mix with photoinitiator and dispersant. Stir to uniformly disperse the components to obtain a photocurable resin slurry; wherein the weight ratio of polyethylene glycol diacrylate, 3,3-dimethicone, diluent, photoinitiator and dispersant is 12~16:26~30:5~9:0.1~0.5:0.1~0.5; Step 2: Use CAD software and slicing software to generate printing files for the resin support to be printed; Step 3: Pour the photocurable resin slurry into the polymer material tank, then import the printing file into the digital light processing 3D printing equipment to create a blank resin support. Step 4: Immerse the blank resin scaffold in a diphenylmethane diisocyanate solution for surface modification to obtain the modified resin scaffold. Step 5: Dissolve the antibacterial agent in N,N-dimethylformamide to prepare an antibacterial coating solution. The antibacterial agent is a polyphenolic antibacterial agent, a nitroimidazole antibacterial agent, or a tetracycline antibacterial agent. The weight ratio of the antibacterial agent to N,N-dimethylformamide is 0.075~1:1. Step 6: Immerse the modified resin scaffold in an antibacterial coating solution and cure it in an oven at 45~60℃ to obtain a resin scaffold with an antibacterial coating grafted on its surface.

[0019] The photocurable resin slurry is used to prepare an osteogenic scaffold substrate with a preset structure; the MDI pretreatment step is used to form a reaction interface on the scaffold surface that is conducive to the fixation of antibacterial components, thereby improving the bonding stability between the coating and the scaffold surface, which is different from the simple physical adsorption method; the antibacterial components are dissolved in organic solvents and then surface treated, which is conducive to the uniform distribution of antibacterial drugs and the formation of a continuous coating; the subsequent cleaning and drying steps help to remove unbound components, improve the coating uniformity, repeatability and safety of use.

[0020] Preferably, in step 1, the number average molecular weight of polyethylene glycol diacrylate is 1000, the purity of 3,3-dimethacrylic acid is ≥97%, the diluent is polypropylene glycol, the photoinitiator is 2,4,6-trimethylbenzoyl diphenylphosphine oxide, and the dispersant is DCA-1228.

[0021] The photoinitiator is selected from acylphosphine oxide photoinitiators, preferably 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and the dispersant is selected from dispersants that can improve the dispersion stability of photocurable resin slurries, preferably DCA-1228.

[0022] The diluent is used to reduce the viscosity of the system, ensure photopolymerization and printing, and not affect subsequent MDI processing and antibacterial coating construction.

[0023] Preferably, photocurable acrylate / methacrylate resins can also be used as resin matrices.

[0024] Preferably, in step 1, the weight ratio of polyethylene glycol diacrylate, 3,3-dimethicone, diluent, photoinitiator and dispersant is 14:28:7:0.3:0.5.

[0025] Preferably, step 2 specifically involves: designing a three-dimensional model of the resin support to be printed in CAD software, exporting it as an STL file, importing the STL file into slicing software, setting printing parameters, and generating a printing file.

[0026] Preferably, step 3 specifically involves: pouring the photocurable resin slurry into the polymer material tank, importing the printing file into the digital light processing 3D printing equipment, curing it layer by layer with ultraviolet light until printing is complete, removing the printed part from the platform after printing, cleaning the printed part in isopropanol to remove uncured resin, and then curing it again under ultraviolet light to ensure that the resin is completely polymerized, thus obtaining a blank resin scaffold.

[0027] Preferably, the surface modification time in step 4 is 20~24h.

[0028] Preferably, in step 5: the polyphenolic antibacterial agent is tannic acid, the nitroimidazole antibacterial agent is ornidazole, and the tetracycline antibacterial agent is minocycline hydrochloride.

[0029] Preferably, the weight ratio of tannic acid to N,N-dimethylformamide is 0.16:1, the weight ratio of ornidazole to N,N-dimethylformamide is 1:1, and the weight ratio of minocycline hydrochloride to N,N-dimethylformamide is 0.075:1.

[0030] Preferably, step 6 specifically involves: immersing the modified resin scaffold in an antibacterial coating solution and curing it in an oven at 45-60°C for 0.5-1.5 hours; then washing the scaffold alternately with anhydrous ethanol and distilled water to remove residual solution from the surface; and finally air-drying it to obtain a resin scaffold with an antibacterial coating grafted onto its surface.

[0031] Preferably, an antibacterial coating based on an MDI-cured resin osteogenic scaffold is provided, wherein the antibacterial coating is prepared by the aforementioned method for preparing an MDI-cured resin osteogenic scaffold antibacterial coating.

[0032] Example 1 Step 1: Preparation of UV-curable resin slurry; Polyethylene glycol diacrylate (PEGDA, Mn=1000; Sinopharm Chemical Reagent Co., Ltd.) and 3,3-dimethacrylic acid (purity ≥97%; Beijing Huawi Ruike Chemical Technology Co., Ltd.) were used as the resin matrix. Polypropylene glycol (PPG, Mn=200; Shanghai Maclean Company) was added as a diluent, and mixed with photoinitiator 2,4,6-trimethylbenzoyl diphenylphosphine oxide (TPO, AR grade; Sinopharm Chemical Reagent Co., Ltd.) and dispersant DCA-1228. The components were uniformly dispersed by thorough stirring to obtain a photocurable resin slurry with a set solid content. The weight ratio of polyethylene glycol diacrylate, 3,3-dimethacrylic acid, diluent, photoinitiator and dispersant was 12:26:5:0.1:0.5.

[0033] Step 2: Design and slicing of the 3D model of the support frame; A 3D structural model of the resin support to be printed was designed using CAD software and exported as an STL file. The STL file was then imported into slicing software, printing parameters were set, and a print file was generated. Before printing, the printing platform was leveled, and the Z-axis zero point position was calibrated.

[0034] Step 3: DLP printing and post-processing of blank resin scaffolds; The above-mentioned photocurable resin slurry was added to the polymer material tank, and the printing file was imported into the digital light processing (DLP) 3D printing equipment (S300+, UnionTech Co., Ltd.). The printing was cured layer by layer by ultraviolet light until the printing was completed. After printing, the printed part was removed and peeled off from the platform. The printed part was placed in isopropanol (purity ≥99%, Sinopharm Chemical Reagent Co., Ltd.) for cleaning to remove uncured resin on the surface. If necessary, ultrasonic cleaning was used to enhance the cleaning effect. The cleaned printed part was then placed in an ultraviolet curing device for secondary curing to ensure that the resin was fully cured and to improve the mechanical properties, resulting in a blank 3D printed resin scaffold.

[0035] Step 4: Surface treatment of blank resin support; The blank resin scaffold, after being fully photocured, was immersed in a solution containing diphenylmethane diisocyanate (MDI) and reacted for 24 hours under set conditions to achieve surface modification of the scaffold.

[0036] Step 5: Preparation of the antibacterial coating solution; Tannic acid powder (AR grade, Beijing Huawi Ruike Chemical Technology Co., Ltd.), ornidazole powder (purity ≥98%, Anaiji (Shanghai) Pharmaceutical Chemical Co., Ltd.), and minocycline hydrochloride powder (purity ≥98%; Beijing Huawi Ruike Chemical Technology Co., Ltd.) were dissolved in 2 mL of N,N-dimethylformamide solution (DMF, AR grade; Sinopharm Chemical Reagent Co., Ltd.). The weight ratio of antibacterial agent to N,N-dimethylformamide was 0.075~1:1 to prepare different antibacterial coating solutions.

[0037] Step 6: Curing and cross-linking reaction, cleaning and drying; The modified resin scaffold treated with MDI obtained in step 4 was immersed in the antibacterial coating solution obtained in step 5 and cured in an oven at 60°C for 1.5 hours to allow the antibacterial components to cure and crosslink with the scaffold surface under the mediation of MDI. After the reaction, the scaffold surface was rinsed with alternating shaking of anhydrous ethanol and distilled water to remove residual solution. Finally, it was air-dried to obtain a 3D printed resin-based osteogenic scaffold with an antibacterial coating grafted on the surface.

[0038] Example 2 Step 1: Preparation of UV-curable resin slurry; Polyethylene glycol diacrylate (PEGDA, Mn=1000; Sinopharm Chemical Reagent Co., Ltd.) and 3,3-dimethacrylic acid (purity ≥97%; Beijing Huawi Ruike Chemical Technology Co., Ltd.) were used as the resin matrix. Polypropylene glycol (PPG, Mn=200; Shanghai Maclean Company) was added as a diluent, and mixed with photoinitiator 2,4,6-trimethylbenzoyl diphenylphosphine oxide (TPO, AR grade; Sinopharm Chemical Reagent Co., Ltd.) and dispersant DCA-1228. The components were uniformly dispersed by thorough stirring to obtain a photocurable resin slurry with a set solid content. The weight ratio of polyethylene glycol diacrylate, 3,3-dimethacrylic acid, diluent, photoinitiator and dispersant was 16:30:9:0.5:0.5.

[0039] Step 2: Design and slicing of the 3D model of the support frame; A 3D structural model of the resin support to be printed was designed using CAD software and exported as an STL file. The STL file was then imported into slicing software, printing parameters were set, and a print file was generated. Before printing, the printing platform was leveled, and the Z-axis zero point position was calibrated.

[0040] Step 3: DLP printing and post-processing of blank resin scaffolds; The above-mentioned photocurable resin slurry was added to the polymer material tank, and the printing file was imported into the digital light processing (DLP) 3D printing equipment (S300+, UnionTech Co., Ltd.). The printing was cured layer by layer by ultraviolet light until the printing was completed. After printing, the printed part was removed and peeled off from the platform. The printed part was placed in isopropanol (purity ≥99%, Sinopharm Chemical Reagent Co., Ltd.) for cleaning to remove uncured resin on the surface. If necessary, ultrasonic cleaning was used to enhance the cleaning effect. The cleaned printed part was then placed in an ultraviolet curing device for secondary curing to ensure that the resin was fully cured and to improve the mechanical properties, resulting in a blank 3D printed resin scaffold.

[0041] Step 4: Surface treatment of blank resin support; The blank resin scaffold, after being fully photocured, was immersed in a solution containing diphenylmethane diisocyanate (MDI) and reacted for 20 hours under set conditions to achieve surface modification of the scaffold.

[0042] Step 5: Preparation of the antibacterial coating solution; Tannic acid powder (AR grade, Beijing Huawi Ruike Chemical Technology Co., Ltd.), ornidazole powder (purity ≥98%, Anaiji (Shanghai) Pharmaceutical Chemical Co., Ltd.), and minocycline hydrochloride powder (purity ≥98%; Beijing Huawi Ruike Chemical Technology Co., Ltd.) were dissolved in 2 mL of N,N-dimethylformamide solution (DMF, AR grade; Sinopharm Chemical Reagent Co., Ltd.). The weight ratio of tannic acid to N,N-dimethylformamide was 0.16:1, the weight ratio of ornidazole to N,N-dimethylformamide was 1:1, and the weight ratio of minocycline hydrochloride to N,N-dimethylformamide was 0.075:1, thus preparing different antibacterial coating solutions.

[0043] Step 6: Curing and cross-linking reaction, cleaning and drying; The modified resin scaffold treated with MDI obtained in step 4 was immersed in the antibacterial coating solution obtained in step 5 and cured in an oven at 45°C for 0.5 h to allow the antibacterial components to cure and crosslink with the scaffold surface under the mediation of MDI. After the reaction, the scaffold surface was rinsed with alternating shaking of anhydrous ethanol and distilled water to remove residual solution. Finally, it was air-dried to obtain a 3D printed resin-based osteogenic scaffold with an antibacterial coating grafted on the surface.

[0044] Example 3 Step 1: Preparation of UV-curable resin slurry; Polyethylene glycol diacrylate (PEGDA, Mn=1000; Sinopharm Chemical Reagent Co., Ltd.) and 3,3-dimethacrylic acid (purity ≥97%; Beijing Huawi Ruike Chemical Technology Co., Ltd.) were used as the resin matrix. Polypropylene glycol (PPG, Mn=200; Shanghai Maclean Company) was added as a diluent, and mixed with photoinitiator 2,4,6-trimethylbenzoyl diphenylphosphine oxide (TPO, AR grade; Sinopharm Chemical Reagent Co., Ltd.) and dispersant DCA-1228. The components were uniformly dispersed by thorough stirring to obtain a photocurable resin slurry with a set solid content. The weight ratio of polyethylene glycol diacrylate, 3,3-dimethacrylic acid, diluent, photoinitiator and dispersant was 14:28:7:0.3:0.5.

[0045] Step 2: Design and slicing of the 3D model of the support frame; A 3D structural model of the resin support to be printed was designed using CAD software and exported as an STL file. The STL file was then imported into slicing software, printing parameters were set, and a print file was generated. Before printing, the printing platform was leveled, and the Z-axis zero point position was calibrated.

[0046] Step 3: DLP printing and post-processing of blank resin scaffolds; The above-mentioned photocurable resin slurry was added to the polymer material tank, and the printing file was imported into the digital light processing (DLP) 3D printing equipment (S300+, UnionTech Co., Ltd.). The printing was cured layer by layer by ultraviolet light until the printing was completed. After printing, the printed part was removed and peeled off from the platform. The printed part was placed in isopropanol (purity ≥99%, Sinopharm Chemical Reagent Co., Ltd.) for cleaning to remove uncured resin on the surface. If necessary, ultrasonic cleaning was used to enhance the cleaning effect. The cleaned printed part was then placed in an ultraviolet curing device for secondary curing to ensure that the resin was fully cured and to improve the mechanical properties, resulting in a blank 3D printed resin scaffold.

[0047] Step 4: Surface treatment of blank resin support; The blank resin scaffold, after being fully photocured, was immersed in a solution containing diphenylmethane diisocyanate (MDI) and reacted for 22 hours under set conditions to achieve surface modification of the scaffold.

[0048] Step 5: Preparation of the antibacterial coating solution; Tannic acid powder (AR grade, Beijing Huawi Ruike Chemical Technology Co., Ltd.), ornidazole powder (purity ≥98%, Anaiji (Shanghai) Pharmaceutical Chemical Co., Ltd.), and minocycline hydrochloride powder (purity ≥98%; Beijing Huawi Ruike Chemical Technology Co., Ltd.) were dissolved in 2 mL of N,N-dimethylformamide solution (DMF, AR grade; Sinopharm Chemical Reagent Co., Ltd.). The weight ratio of tannic acid to N,N-dimethylformamide was 0.16:1, the weight ratio of ornidazole to N,N-dimethylformamide was 1:1, and the weight ratio of minocycline hydrochloride to N,N-dimethylformamide was 0.075:1, thus preparing different antibacterial coating solutions.

[0049] Step 6: Curing and cross-linking reaction, cleaning and drying; The modified resin scaffold treated with MDI obtained in step 4 was immersed in the antibacterial coating solution obtained in step 5 and cured in an oven at 50°C for 1 hour to allow the antibacterial components to cure and crosslink with the scaffold surface under the mediation of MDI. After the reaction, the scaffold surface was rinsed with alternating shaking of anhydrous ethanol and distilled water to remove residual solution. Finally, it was air-dried to obtain a 3D printed resin-based osteogenic scaffold with an antibacterial coating grafted on the surface.

[0050] Application Example 1: Bacterial Biofilm Coating Experiment; like Figure 2 As shown, the control stent, tannic acid coated stent, ornidazole coated stent, and minocycline hydrochloride coated stent were prepared by following the steps (the specific preparation parameters are the same as in Example 3). Step 1: 3D printing of bone scaffolds; Step 2: UV curing; Step 3: MDI solution treatment; Step 4: Immerse in different antibacterial coating solutions; Step 5: Dry at a constant temperature; Step 6: Ultrasonic cleaning; Step 7: Obtain different antibacterial coating scaffolds; b, blank resin scaffold + MDI blank coating, c, blank resin scaffold + MDI tannic acid coating, d, blank resin scaffold + MDI ornidazole coating, e, blank resin scaffold + MDI minocycline hydrochloride coating. Control groups were set up: a) blank resin scaffold, f) bacterial control group; The above-mentioned scaffolds were co-cultured with bacteria (Staphylococcus aureus and Escherichia coli). After 24 hours of co-culture, 20 μL of bacterial culture from each group was taken, diluted 10,000 times with PBS, and then 30 μL was taken and spread onto LB sterile solid culture plates. After incubating at 37°C for 24 hours, the culture plates were taken out, photographed, and the number of single colonies (CFU) was recorded. The experiment was repeated 3 times.

[0051] like Figure 3 The image shows the Staphylococcus aureus coating results of each group of scaffolds (ns: indicates no significant difference between groups). This indicates that p < 0.01; (Indicated by p < 0.001), it can be seen that scaffolds c, d, and e have a significant inhibitory effect on Staphylococcus aureus.

[0052] like Figure 4 The image shows the E. coli coating results of each group of scaffolds (ns: indicates no significant difference between groups). (Indicated by p < 0.01), it can be seen that scaffolds c, d, and e have a significant inhibitory effect on Escherichia coli.

[0053] Application Example 2: Observation using a laser confocal microscope; Take 100 μL of bacterial suspension from each group after 24 hours of culture as described in Application Example 1, place it on a coverslip in the well chamber, and stain the bacterial suspension according to the instructions of the live / dead bacteria double staining kit. Mix STY09 and PI reagents and stain each group of bacterial suspension. After adding the reagents, incubate in the dark for 15 minutes. Immediately after incubation, observe the bacterial suspension using a laser confocal microscope and record the results of different fluorescence signals.

[0054] like Figure 5 The image shows the results of laser confocal microscopy for each group of scaffolds (Staphylococcus aureus). The red arrows indicate dead bacteria. It can be seen that scaffolds c, d, and e can significantly kill Staphylococcus aureus and have a significant inhibitory effect.

[0055] like Figure 6 The image shows the results of laser confocal microscopy for each group of scaffolds (E. coli). The red arrows indicate dead bacteria. Scaffolds c, d, and e can significantly kill E. coli and have a significant inhibitory effect.

[0056] Application Example 3: Scanning Electron Microscopy (SEM) Detection; The scaffold samples from Application Example 1, cultured for 24 hours, were removed and repeatedly rinsed with PBS. Then, bacteria on the sample surface were fixed with 2.5% glutaraldehyde for 2 hours. Afterward, the samples were dehydrated for 10 minutes each at four alcohol gradients (25%, 50%, 75%, and 100%), and then dried in a vacuum oven at low temperature or air-dried. SEM sample preparation was then performed by attaching the samples to the observation stage and sputtering a gold film onto the surface. Under vacuum conditions, using a 3kV accelerating voltage as the operating condition, the optimal magnification was obtained through system adjustments to observe the bacterial morphology on the surface of each sample.

[0057] like Figure 7 As shown, the SEM images of Staphylococcus aureus on the scaffolds in group ae are shown. The red arrows indicate abnormal bacterial morphology and / or membrane rupture. It can be seen that scaffolds c, d and e can cause abnormal bacterial morphology and / or membrane rupture of Staphylococcus aureus, effectively inhibiting Staphylococcus aureus.

[0058] like Figure 8 As shown, the SEM images of Escherichia coli on the scaffolds in group ae are shown. The red arrows indicate abnormal bacterial morphology and / or membrane rupture. It can be seen that scaffolds c, d, and e can cause abnormal bacterial morphology and / or membrane rupture in Escherichia coli, effectively inhibiting Escherichia coli.

[0059] The preferred embodiments of this application have been described in detail above. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application.

[0060] Many other changes and modifications can be made without departing from the concept and scope of this application. It should be understood that this application is not limited to the specific embodiments, and the scope of this application is defined by the appended claims.

Claims

1. A method for preparing an antibacterial coating for an MDI-cured resin osteogenic scaffold, characterized in that, Includes the following steps: Step 1: Using polyethylene glycol diacrylate and 3,3-dimethicone as the resin matrix, add diluent, and mix with photoinitiator and dispersant. Stir to uniformly disperse the components to obtain a photocurable resin slurry; wherein the weight ratio of polyethylene glycol diacrylate, 3,3-dimethicone, diluent, photoinitiator and dispersant is 12~16:26~30:5~9:0.1~0.5:0.1~0.5; Step 2: Use CAD software and slicing software to generate printing files for the resin support to be printed; Step 3: Pour the photocurable resin slurry into the polymer material tank, then import the printing file into the digital light processing 3D printing equipment to create a blank resin support. Step 4: Immerse the blank resin scaffold in a diphenylmethane diisocyanate solution for surface modification to obtain the modified resin scaffold. Step 5: Dissolve the antibacterial agent in N,N-dimethylformamide to prepare an antibacterial coating solution. The antibacterial agent is a polyphenolic antibacterial agent, a nitroimidazole antibacterial agent, or a tetracycline antibacterial agent. The weight ratio of the antibacterial agent to N,N-dimethylformamide is 0.075~1:

1. Step 6: Immerse the modified resin scaffold in an antibacterial coating solution and cure it in an oven at 45~60℃ to obtain a resin scaffold with an antibacterial coating grafted on its surface.

2. The method for preparing an antibacterial coating for an MDI-cured resin osteogenic scaffold according to claim 1, characterized in that, In step 1, the number average molecular weight of polyethylene glycol diacrylate is 1000, the purity of 3,3-dimethylacrylic acid is ≥97%, the diluent is polypropylene glycol, the photoinitiator is 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and the dispersant is DCA-1228.

3. The method for preparing an antibacterial coating for an MDI-cured resin osteogenic scaffold according to claim 1, characterized in that, In step 1, the weight ratio of polyethylene glycol diacrylate, 3,3-dimethicone, diluent, photoinitiator, and dispersant is 14:28:7:0.3:0.

5.

4. The method for preparing an antibacterial coating for an MDI-cured resin osteogenic scaffold according to claim 1, characterized in that, Step 2 specifically involves: designing a 3D model of the resin support to be printed in CAD software, exporting it as an STL file, importing the STL file into slicing software, setting printing parameters, and generating a printing file.

5. The method for preparing an antibacterial coating for an MDI-cured resin osteogenic scaffold according to claim 1, characterized in that, Step 3 specifically involves: pouring the photocurable resin slurry into the polymer material tank, importing the printing file into the digital light processing 3D printing equipment, curing it layer by layer with ultraviolet light until printing is complete, removing the printed part from the platform after printing, cleaning the printed part in isopropanol to remove uncured resin, and then curing it a second time under ultraviolet light to ensure that the resin is completely polymerized, thus obtaining a blank resin scaffold.

6. The method for preparing an antibacterial coating for an MDI-cured resin osteogenic scaffold according to claim 1, characterized in that, The surface modification time in step 4 is 20~24h.

7. The method for preparing an antibacterial coating for an MDI-cured resin osteogenic scaffold according to claim 1, characterized in that, In step 5: the polyphenolic antibacterial agent is tannic acid, the nitroimidazole antibacterial agent is ornidazole, and the tetracycline antibacterial agent is minocycline hydrochloride.

8. The method for preparing an antibacterial coating for an MDI-cured resin osteogenic scaffold according to claim 7, characterized in that, The weight ratio of tannic acid to N,N-dimethylformamide is 0.16:1, the weight ratio of ornidazole to N,N-dimethylformamide is 1:1, and the weight ratio of minocycline hydrochloride to N,N-dimethylformamide is 0.075:

1.

9. The method for preparing an antibacterial coating for an MDI-cured resin osteogenic scaffold according to claim 1, characterized in that, Step 6 specifically involves immersing the modified resin scaffold in an antibacterial coating solution and curing it in an oven at 45-60°C for 0.5-1.5 hours. The scaffold is then washed alternately with anhydrous ethanol and distilled water to remove residual solution from the surface. Finally, it is air-dried to obtain a resin scaffold with an antibacterial coating grafted onto its surface.

10. An antibacterial coating for an MDI-cured resin osteogenic scaffold, characterized in that, The antibacterial coating of the resin osteogenic scaffold is prepared by a method for preparing an MDI-cured resin osteogenic scaffold antibacterial coating as described in any one of claims 1 to 9.

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