Zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite wound dressing and preparation method thereof

Abstract

The invention discloses a zinc-doped graphene phase carbon nitride-manganese dioxide / polymer composite wound dressing and a preparation method thereof, comprising: in-situ growing manganese dioxide on the surface of zinc-doped graphene phase carbon nitride to construct a zinc-doped graphene phase carbon nitride-manganese dioxide heterojunction composite powder, then mixing and stirring with polymer powder to obtain zinc-doped graphene phase carbon nitride-manganese dioxide / polymer composite powder, dispersing it into dichloromethane to prepare a suspension, then mixing and stirring with N, N-dimethylformamide, and finally preparing zinc-doped graphene phase carbon nitride-manganese dioxide / polymer composite wound dressing by electrostatic spinning technology. The composite wound dressing prepared by the present invention can simultaneously achieve PDT and mPTT under dual light irradiation. At the same time, mild photothermal treatment of manganese dioxide can increase catalase and GPx activity, increase the generation of reactive oxygen species, help kill bacteria, and improve anti-biofilm performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of compound material preparation, and more specifically, relates to a zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite wound dressing and a preparation method thereof. Background Art

[0002] Wound healing is a complex repair process that can be broadly divided into four phases: coagulation, inflammation, epidermal cell migration and proliferation, and epithelial formation and remodeling. The discovery of polymer composite wound dressings promotes wound healing without triggering an inflammatory response. These polymer composite wound dressings hold great promise for future applications. Compared with traditional wound dressings, polymer composite wound dressings offer advantages such as improved absorbency, selective permeability, excellent conformability, and scar-free properties. However, in clinical practice, bacteria often adhere to the surface of wound dressings, forming dense bacterial biofilms, leading to wound dressing failure. Furthermore, during biofilm formation, bacteria produce hydrogen peroxide, which weakens the immune system and enhances resistance to antibiotics and immune cells. Therefore, biofilm formation can easily lead to persistent bacterial infections, seriously threatening patients' lives and health. Therefore, developing effective methods to remove bacterial biofilms from composite wound dressings is imperative.

[0003] In order to solve the above problems, people have been committed to developing new antibacterial materials such as antimicrobial peptides and heavy metal ions to protect the public from bacterial infections. However, their high prices and potential biological toxicity limit their practical applications. Photodynamic therapy (PDT) uses photosensitizers to generate reactive oxygen species (ROS, such as 1 O2, ·OH and O2 - ), is a popular antibacterial strategy. PDT has attracted widespread attention for its ability to destroy the biofilm matrix and kill bacteria with less harm to normal tissues. Among all types of photosensitizers, two-dimensional graphene-phase carbon nitride (g-C3N4) composed of tri-s-triazine units bridged by tertiary nitrogen has broad application prospects in PDT due to its excellent biocompatibility, good stability and moderate band gap (2.7eV). At the same time, Zn doping of g-C3N4 can further improve the PDT efficiency of g-C3N4 under visible light (VL) irradiation. However, the insufficient O2 supply in bacterial biofilms limits the production of ROS in bacterial biofilms. Therefore, it is of great significance and challenge to simultaneously achieve sufficient O2 supply and ROS generation to overcome hypoxia-related resistance.

[0004] In recent years, researchers have conducted various studies to overcome hypoxia in biofilms. Catalase can decompose endogenous hydrogen peroxide (H2O2) in bacterial biofilms to produce O2, which has a significant effect on enhancing the photodynamic effect. MnO2 has excellent catalase-like activity and can consume H2O2 to achieve self-supply of O2. Excitingly, MnO2 exhibits strong light absorption in the near-infrared light region and can produce a mild photothermal effect under near-infrared light irradiation. Mild photothermal therapy (mPTT) can increase the permeability of biofilms and enhance the activity of catalase. At the same time, MnO2 also has glutathione peroxidase (GPx) activity, which consumes glutathione (GSH) in bacteria, thereby weakening the bacterial antioxidant system. However, in the prior art, there is still no research on compounding zinc-doped graphene-phase carbon nitride with manganese dioxide and incorporating it into a polymer to prepare a wound dressing. Summary of the Invention

[0005] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0006] To achieve these objectives and other advantages of the present invention, a zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite wound dressing and a preparation method thereof are provided. Manganese dioxide is first grown in situ on the surface of zinc-doped graphene-phase carbon nitride to construct a zinc-doped graphene-phase carbon nitride-manganese dioxide heterojunction composite powder. The powder is then mixed and stirred uniformly with a polymer powder to obtain a zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite powder. The powder is then dispersed in dichloromethane to form a suspension, which is then mixed and stirred with N,N-dimethylformamide. Finally, the zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite wound dressing is prepared by electrospinning technology.

[0007] Preferably, the polymer powder is at least one of polylactic acid, polyglycolic acid, polylactic acid-hydroxyglycolic acid copolymer, polycaprolactone, and polydioxanone.

[0008] Preferably, in the zinc-doped graphene phase carbon nitride-manganese dioxide / polymer composite wound dressing, the mass fraction of zinc-doped graphene phase carbon nitride-manganese dioxide is 1 to 20 wt%, the mass fraction of the polymer is 80 to 99 wt%, the particle size of the polymer powder is 40 to 60 μm, and the particle size of the zinc-doped graphene phase carbon nitride-manganese dioxide heterojunction composite powder is 4 to 10 μm.

[0009] A method for preparing a zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite wound dressing comprises the following steps:

[0010] Step 1: placing melamine in a muffle furnace and heating it from room temperature to a first temperature for a first preset time to obtain a block, then grinding it into powder, and then continuing to heat the powder at the first temperature for a first preset time to obtain graphene-phase carbon nitride nanosheets;

[0011] Step 2: dissolving the prepared graphene-phase carbon nitride nanosheets in deionized water at a mass volume ratio of 0.97 g of graphene-phase carbon nitride nanosheets to deionized water to 20-40 mL, and ultrasonically treating for a second preset time; subsequently, adding zinc acetate according to a first mass ratio of graphene-phase carbon nitride nanosheets to zinc acetate, and stirring at a second temperature until the liquid is completely volatilized; then drying the resulting product, placing the product in a muffle furnace at a first temperature for a first preset time, and finally obtaining zinc-doped graphene-phase carbon nitride nanosheets;

[0012] Step 3, dissolving the prepared zinc-doped graphene-phase carbon nitride nanosheets in deionized water, the mass volume ratio of the zinc-doped graphene-phase carbon nitride nanosheets to deionized water is 20 mg: 2-4 mL, and ultrasonically treating for a second preset time, recorded as solution A; then weighing manganese chloride according to the second mass ratio of zinc-doped graphene-phase carbon nitride nanosheets to manganese chloride and dissolving it in deionized water, the mass volume ratio of manganese chloride to deionized water is 148.5 mg: 30-50 mL, recorded as solution B; then mixing solution A and solution B evenly, adding tetramethylammonium hydroxide and hydrogen peroxide at a fifth temperature and stirring for a fourth preset time, then collecting the brown precipitate by centrifugation, washing three times with deionized water, washing three times with methanol, and drying the resulting product to obtain a zinc-doped graphene-phase carbon nitride-manganese dioxide composite heterojunction powder;

[0013] Step 4. According to the third preset mass ratio, a certain amount of zinc-doped graphene phase carbon nitride-manganese dioxide heterojunction powder and polymer powder are weighed and evenly mixed, dispersed into dichloromethane with a fourth preset mass ratio to form a suspension, and then mixed with N,N-dimethylformamide and stirred for 3 hours, wherein the mass ratio of dichloromethane to N,N-dimethylformamide is 4:1, and finally, a zinc-doped graphene phase carbon nitride-manganese dioxide / polymer composite wound dressing is prepared by electrospinning technology.

[0014] Preferably, in step 1, the first temperature is 550° C., and the first preset time is 4 hours.

[0015] Preferably, in step 2, the second preset time is 30 minutes, the first preset mass ratio is 0.97:0.03, and the second temperature is 80°C.

[0016] Preferably, in step three, the second preset mass ratio is 1.34:1, the fifth temperature is 25°C, and the fourth preset time is 12h; the mass volume ratio of the zinc-doped graphene-phase carbon nitride nanosheets to tetramethylammonium hydroxide is 1g:30mL, the mass volume ratio of the zinc-doped graphene-phase carbon nitride nanosheets to hydrogen peroxide is 1g:7.5mL, and the concentration of hydrogen peroxide is 60mM; the centrifugal speed is 7000-8000r / min, and the time is 4-6min.

[0017] Preferably, in step 4, the third preset mass ratio is 1-20:80-99, and the fourth preset mass ratio is 0.4-0.6:4.32-7.52.

[0018] Preferably, in step four, the electrospinning technology is used to prepare the wound dressing, and the obtained material is placed in an electrospinning system for spinning, the spinning machine voltage is 15-19 kV, the ambient temperature is 25-35 ° C, the humidity is 45-65%, the pushing speed is 0.007 mm / s, and the distance between the needle and the contact surface is 4 cm.

[0019] Preferably, the prepared zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite wound dressing is applied to a novel skin wound implant material.

[0020] The present invention has at least the following beneficial effects: the wound dressing obtained by the present invention has low toxicity, low cost, and good porosity, which is conducive to killing bacteria on the wound dressing and promoting cell regeneration. In addition, it has the advantages of fast and efficient near-infrared light combined with visible light anti-biofilm and antibacterial properties. The wound dressing of the present invention can simultaneously achieve PDT and mPTT under dual light irradiation, MnO2 continuously catalyzes H2O2 to generate O2, and ZnCN uses sufficient O2 to generate under VL irradiation. 1 O2 and ·OH enhance the PDT effect. Mild photothermal treatment with MnO2 further enhances the activities of catalase and GPx, increasing the production of reactive oxygen species, thereby successfully eliminating bacterial biofilms.

[0021] In summary, the zinc-doped graphene phase carbon nitride-manganese dioxide / polymer powder prepared in the present invention, the electrospinning technology used, and the zinc-doped graphene phase carbon nitride-manganese dioxide content in the composite material are the results of the inventor's multiple experiments and creative work. The present invention controls the content of zinc-doped graphene phase carbon nitride-manganese dioxide and adjusts the electrospinning process parameters to prepare a zinc-doped graphene phase carbon nitride-manganese dioxide / polymer wound dressing to address the problem of bacterial infection of related dressings, and has broad application value in the biomedical field.

[0022] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a scanning electron micrograph of the ZnCN-MnO2 / PLLA composite wound dressing prepared in Example 1;

[0024] Figure 2 This is a product picture of the ZnCN-MnO2 / PLLA composite wound dressing prepared in Example 1;

[0025] Figure 3 This is a diagram showing the antibacterial biofilm effect of PLLA wound dressing;

[0026] Figure 4 This is a diagram showing the antibacterial biofilm effect of the ZnCN-MnO2 / PLLA composite wound dressing prepared in Example 1;

[0027] Figure 5 This is a diagram showing the antibacterial effect of PLLA wound dressing;

[0028] Figure 6 This is a diagram showing the antibacterial effect of the ZnCN-MnO2 / PLLA composite wound dressing prepared in Example 1;

[0029] Figure 7 This is a diagram showing the cell regeneration effect of PLLA wound dressing;

[0030] Figure 8 This is a diagram showing the cell regeneration effect of the ZnCN-MnO2 / PLLA composite wound dressing prepared in Example 1. DETAILED DESCRIPTION

[0031] The present invention will be described in further detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0032] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0033] Example 1:

[0034] Step 1: Preparation of graphene-phase carbon nitride nanosheets (g-C3N4): Pour melamine powder into an alumina crucible, then cover the crucible with a lid and place the crucible in a muffle furnace for high-temperature calcination at a heating rate of 5°C / min. Raise the furnace temperature from room temperature to 550°C and maintain it at the current temperature for 4 hours. After cooling to room temperature, remove the crucible from the furnace to obtain a pale yellow block. After grinding, calcine it again at 550°C for 4 hours to obtain graphene-phase carbon nitride nanosheets (g-C3N4).

[0035] Step 2, preparation process of zinc-doped graphene-phase carbon nitride nanosheets (ZnCN): ultrasonically disperse 0.97g g-C3N4 in 30mL deionized water for 30min; add 0.03g zinc acetate to the above solution, continue stirring at 80°C until the water in the beaker is completely evaporated, collect the light yellow powder, dry it in a drying oven at 60°C for 6h, put the powder into a crucible, put it into a muffle furnace, heat it to 550°C at a heating rate of 5°C / min, and keep it warm for 4h. After natural cooling, collect the powder and grind it into fine powder to obtain ZnCN;

[0036] Step 3: In situ growth of MnO2 on the ZnCN surface: First, 200 mg of ZnCN powder was added to 30 mL of deionized water and ultrasonicated for 30 min to obtain solution A. Subsequently, 148.5 mg of MnCl2·4H2O was dissolved in 40 mL of deionized water to obtain solution B. Solution A and solution B were mixed evenly. Then, 6 mL of TMA.OH and 1.5 mL of 60 mM H2O2 solution were added to the above solution, and the mixture was slowly stirred at 25 ° C for 12 h. After centrifugation at 7000 r / min for 5 min, the brown precipitate was collected, washed three times with deionized water and three times with methanol, and freeze-dried to prepare ZnCN-MnO2 composite powder;

[0037] Step 4: Mix the ZnCN-MnO2 composite powder and left-rotating polylactic acid (PLLA) powder in a mass ratio of 1:99 (the content of ZnCN-MnO2 is 1%) to obtain 600 mg of ZnCN-MnO2 / PLL A composite powder, then add 7.52 g of dichloromethane and 1.88 g of N, N-dimethylformamide and stir for 3 hours; then spin the obtained material in an electrospinning system with a spinning machine voltage of 15-19 kV, an ambient temperature of 29°C, a humidity of 55%, a pushing speed of 0.007 mm / s, and a distance between the needle and the contact surface of 4 cm. After drying, a zinc-doped graphene phase carbon nitride-manganese dioxide / polymer (ZnCN-MnO2 / PLLA) composite wound dressing is obtained, and its scanning electron microscope image is as shown below. Figure 1 shown.

[0038] The bacterial biofilm integrity test was conducted using the ZnCN-MnO2 / PLLA composite wound dressing prepared in this example and the existing PLLA wound dressing: 50 μL of bacterial suspension (1×10 6 CFU / mL) was inoculated into 200 μL LB bacterial solution (96-well plate) and co-cultured at 37°C for 48 h. Bacterial biofilms were formed after ZnCN-MnO2 / PLLA composite wound dressings and PLLA wound dressings were placed separately. After incubation for 48 h, the wounds were irradiated with 660 nm VL + 808 nm NIR dual light for 30 min. In order to evaluate the destruction of the biofilm formed by bacteria in the composite dressing, the samples were stained with crystal violet. After removing the bacterial suspension from the 96-well plate, the biofilm on the plate was rinsed with 200 μL PBS solution and fixed with 200 μL anhydrous ethanol. After 30 minutes, anhydrous ethanol was removed from the 96-well plate and 200 μL (1%) crystal violet (CV) was added to the 96-well plate for staining. Finally, after the crystal violet staining solution was naturally dried, the bacterial biofilm was photographed with a digital camera. Figure 3 This is the antibacterial biofilm effect of PLLA wound dressing. Figure 4 This is a diagram showing the anti-bacterial biofilm effect of the ZnCN-MnO2 / PLLA composite wound dressing. It can be seen that the composite wound dressing obtained by this invention has good anti-biofilm performance.

[0039] The antibacterial experiment was conducted using the ZnCN-MnO2 / PLLA composite wound dressing prepared in this example and the existing PLLA wound dressing: First, the ZnCN-MnO2 / PLLA composite wound dressing prepared in this example and the PLLA wound dressing were immersed in 1×10 6 CFU / mL of bacterial solution was cultured at 37°C for 24 hours, then irradiated under near-infrared light for 15 minutes, 1 μL of bacterial solution was taken out and diluted 10,000 times, 100 μL of the diluted bacterial solution was dropped onto the agar plate, and mixed evenly using the spread plate method. After the agar plate was incubated at 37°C for 12 hours, the colonies on the agar plate were photographed with a digital camera. Figure 5 This is the antibacterial effect diagram of PLLA wound dressing. Figure 6 This is the antibacterial effect diagram of the ZnCN-MnO2 / PLLA composite wound dressing. It can be seen that the composite wound dressing obtained by this invention has good antibacterial properties and the number of bacterial particles is significantly smaller.

[0040] The ZnCN-MnO2 / PLLA composite wound dressing prepared in this example and the existing PLLA wound dressing were used to conduct a cytotoxicity experiment to observe the cell regeneration effect. The specific steps were as follows: 240 mg of the ZnCN-MnO2 / PLLA composite wound dressing and the PLLA wound dressing were respectively immersed in a 15 mL centrifuge tube containing 7 mL of DMEM culture medium solution, and cultured at 37°C and 5% CO2 for 24 hours. The culture medium was then extracted into a new 15 mL centrifuge tube, and the extracts of different dressings were placed in a 4°C environment for subsequent experiments. The seeding density in each well of a 96-well plate was 1×10 4 150 μL of mBMSCs cell suspension at 150 cells / mL was incubated for 1 day, and 150 μL of the extract was replaced in each well. The incubation continued for 3 days, and the extract was replaced every other day. Calcein-AM (Shanghai, China) and propylene iodide (PI, Shanghai, China) were used to evaluate the live / dead staining of mBMSCs. AM / PI stain was prepared according to the volume ratio of AM:PI:PBS = 1 μL:1 μL:1000 μL. 150 μL of AM / PI stain was added to a 96-well plate. After incubation in the dark at room temperature for 30 minutes, the wells were washed twice with PBS. The treated 96-well plate was placed under a fluorescence microscope (BX53F2, OLYMPUS, Tokyo, Japan), and the morphology and number of live / dead mBMSCs were observed by photographing. Figure 7 This is the cell regeneration effect diagram of PLLA wound dressing. Figure 8 This is a diagram of the cell regeneration effect of the ZnCN-MnO2 / PLLA composite wound dressing prepared in Example 1. It can be seen that the cells cultured with the composite wound dressing obtained by this invention have no obvious cytotoxicity and the cell reproduction is in good condition. The zinc-doped graphene phase carbon nitride-manganese dioxide / polymer composite wound dressing prepared by the present invention has good wound healing performance.

[0041] Example 2:

[0042] Step 1: Preparation of graphene-phase carbon nitride nanosheets (g-C3N4): Pour melamine powder into an alumina crucible, then cover the crucible with a lid and place the crucible in a muffle furnace for high-temperature calcination at a heating rate of 5°C / min. Raise the furnace temperature from room temperature to 550°C and maintain it at the current temperature for 4 hours. After cooling to room temperature, remove the crucible from the furnace to obtain a pale yellow block. After grinding, calcine it again at 550°C for 4 hours to obtain graphene-phase carbon nitride nanosheets (g-C3N4).

[0043] Step 2, preparation process of zinc-doped graphene-phase carbon nitride nanosheets (ZnCN): ultrasonically disperse 0.97g g-C3N4 in 30mL deionized water for 30min; add 0.03g zinc acetate to the above solution, continue stirring at 80°C until the water in the beaker is completely evaporated, collect the light yellow powder, dry it in a drying oven at 60°C for 6h, put the powder into a crucible, put it into a muffle furnace, heat it to 550°C at a heating rate of 5°C / min, and keep it warm for 4h. After natural cooling, collect the powder and grind it into fine powder to obtain ZnCN;

[0044] Step 3: In situ growth of MnO2 on the ZnCN surface: First, 200 mg of ZnCN powder was added to 30 mL of deionized water and ultrasonicated for 30 min to obtain solution A. Subsequently, 148.5 mg of MnCl2·4H2O was dissolved in 40 mL of deionized water to obtain solution B. Solution A and solution B were mixed evenly. Then, 6 mL of TMA.OH and 1.5 mL of 60 mM H2O2 solution were added to the above solution, and the mixture was slowly stirred at 25 ° C for 12 h. After centrifugation at 7000 r / min for 5 min, the brown precipitate was collected, washed three times with deionized water and three times with methanol, and freeze-dried to prepare ZnCN-MnO2 composite powder;

[0045] Step 4. Mix the ZnCN-MnO2 composite powder and left-lactic acid (PLLA) powder in a mass ratio of 5:95 (the content of ZnCN-MnO2 is 5%) to obtain 600 mg of ZnCN-MnO2 / PLLA composite powder, then add 7.52 g of dichloromethane and 1.88 g of N,N-dimethylformamide and stir for 3 hours; then spin the resulting material in an electrospinning system with a spinning machine voltage of 15-19 kV, an ambient temperature of 29°C, a humidity of 55%, a pushing speed of 0.007 mm / s, and a distance between the needle and the contact surface of 4 cm. After drying, a zinc-doped graphene phase carbon nitride-manganese dioxide / polymer composite wound dressing is obtained.

[0046] Example 3:

[0047] Step 1: Preparation of graphene-phase carbon nitride nanosheets (g-C3N4): Pour melamine powder into an alumina crucible, then cover the crucible with a lid and place the crucible in a muffle furnace for high-temperature calcination at a heating rate of 5°C / min. Raise the furnace temperature from room temperature to 550°C and maintain it at the current temperature for 4 hours. After cooling to room temperature, remove the crucible from the furnace to obtain a pale yellow block. After grinding, calcine it again at 550°C for 4 hours to obtain graphene-phase carbon nitride nanosheets (g-C3N4).

[0048] Step 2, preparation process of zinc-doped graphene-phase carbon nitride nanosheets (ZnCN): ultrasonically disperse 0.97g g-C3N4 in 30mL deionized water for 30min; add 0.03g zinc acetate to the above solution, continue stirring at 80°C until the water in the beaker is completely evaporated, collect the light yellow powder, dry it in a drying oven at 60°C for 6h, put the powder into a crucible, put it into a muffle furnace, heat it to 550°C at a heating rate of 5°C / min, and keep it warm for 4h. After natural cooling, collect the powder and grind it into fine powder to obtain ZnCN;

[0049] Step 3: In situ growth of MnO2 on the ZnCN surface: First, 200 mg of ZnCN powder was added to 30 mL of deionized water and ultrasonicated for 30 min to obtain solution A. Subsequently, 148.5 mg of MnCl2·4H2O was dissolved in 40 mL of deionized water to obtain solution B. Solution A and solution B were mixed evenly. Then, 6 mL of TMA.OH and 1.5 mL of 60 mM H2O2 solution were added to the above solution, and the mixture was slowly stirred at 25 ° C for 12 h. After centrifugation at 7000 r / min for 5 min, the brown precipitate was collected, washed three times with deionized water and three times with methanol, and freeze-dried to prepare ZnCN-MnO2 composite powder;

[0050] Step 4. Mix the ZnCN-MnO2 composite powder and left-rotatory polylactic acid (PLLA) powder in a mass ratio of 10:90 (the content of ZnCN-MnO2 is 10%) to obtain 600 mg of ZnCN-MnO2 / PLLA composite powder, then add 7.52 g of dichloromethane and 1.88 g of N,N-dimethylformamide and stir for 3 hours; then spin the resulting material in an electrospinning system with a spinning machine voltage of 15-19 kV, an ambient temperature of 29°C, a humidity of 55%, a pushing speed of 0.007 mm / s, and a distance between the needle and the contact surface of 4 cm. After drying, a zinc-doped graphene phase carbon nitride-manganese dioxide / polymer composite wound dressing is obtained.

[0051] Example 4:

[0052] Step 1: Preparation of graphene-phase carbon nitride nanosheets (g-C3N4): Pour melamine powder into an alumina crucible, then cover the crucible with a lid and place the crucible in a muffle furnace for high-temperature calcination at a heating rate of 5°C / min. Raise the furnace temperature from room temperature to 550°C and maintain it at the current temperature for 4 hours. After cooling to room temperature, remove the crucible from the furnace to obtain a pale yellow block. After grinding, calcine it again at 550°C for 4 hours to obtain graphene-phase carbon nitride nanosheets (g-C3N4).

[0053] Step 2, preparation process of zinc-doped graphene-phase carbon nitride nanosheets (ZnCN): ultrasonically disperse 0.97g g-C3N4 in 30mL deionized water for 30min; add 0.03g zinc acetate to the above solution, continue stirring at 80°C until the water in the beaker is completely evaporated, collect the light yellow powder, dry it in a drying oven at 60°C for 6h, put the powder into a crucible, and then put it into a muffle furnace, heat it to 550°C at a heating rate of 5°C / min, and keep it warm for 4h. After natural cooling, collect the powder and grind it into fine powder to obtain ZnCN;

[0054] Step 3: In situ growth of MnO2 on the ZnCN surface: First, 200 mg of ZnCN powder was added to 30 mL of deionized water and ultrasonicated for 30 min to obtain solution A. Subsequently, 148.5 mg of MnCl2·4H2O was dissolved in 40 mL of deionized water to obtain solution B. Solution A and solution B were mixed evenly. Then, 6 mL of TMA.OH and 1.5 mL of 60 mM H2O2 solution were added to the above solution, and the mixture was slowly stirred at 25 ° C for 12 h. After centrifugation at 7000 r / min for 5 min, the brown precipitate was collected, washed three times with deionized water and three times with methanol, and freeze-dried to prepare ZnCN-MnO2 composite powder;

[0055] Step 4. Mix the ZnCN-MnO2 composite powder and left-lactic acid (PLLA) powder in a mass ratio of 20:80 (the content of ZnCN-MnO2 is 20%) to obtain 600 mg of ZnCN-MnO2 / PLLA composite powder, then add 7.52 g of dichloromethane and 1.88 g of N,N-dimethylformamide and stir for 3 hours; then spin the resulting material in an electrospinning system with a spinning machine voltage of 15-19 kV, an ambient temperature of 29°C, a humidity of 55%, a pushing speed of 0.007 mm / s, and a distance between the needle and the contact surface of 4 cm. After drying, a zinc-doped graphene phase carbon nitride-manganese dioxide / polymer composite wound dressing is obtained.

[0056] To address the significant differences in conditions among patients, the optimal therapeutic effect is achieved by adjusting the size and active ingredient ratio of the zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite wound dressing. The antimicrobial properties of the zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite wound dressing vary at different ratios. A ratio of 20:80 is the critical limit for electrospinning, at which point its antimicrobial effect is maximized. However, excessive heavy metals can lead to immune rejection in the human body. Since adults have stronger immunity than middle-aged and elderly people, a zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite wound dressing with a ratio of 20:80 can be used to enhance the antimicrobial effect for wound infections on the skin of middle-aged and elderly people.

[0057] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite wound dressing, characterized in that: The preparation method of the zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite wound dressing comprises the following steps: Step 1: placing melamine in a muffle furnace and heating it from room temperature to a first temperature for a first preset time to obtain a block, then grinding it into powder, and then continuing to heat the powder at the first temperature for a first preset time to obtain graphene-phase carbon nitride nanosheets; Step 2: dissolving the graphene-phase carbon nitride nanosheets in deionized water at a mass volume ratio of 0.97 g of graphene-phase carbon nitride nanosheets to deionized water to 20-40 mL, and ultrasonically treating for a second preset time; then adding zinc acetate according to a first preset mass ratio of graphene-phase carbon nitride nanosheets to zinc acetate, and stirring at a second temperature until the liquid is completely volatilized; then drying the resulting product, placing the product in a muffle furnace at a first temperature for a first preset time, and finally obtaining zinc-doped graphene-phase carbon nitride nanosheets; Step 3, dissolving the zinc-doped graphene-phase carbon nitride nanosheets in deionized water, the mass volume ratio of the zinc-doped graphene-phase carbon nitride nanosheets to deionized water is 20 mg: 2~4 mL, and ultrasonically treating for a second preset time, recorded as solution A; then weighing manganese chloride according to the second preset mass ratio of the zinc-doped graphene-phase carbon nitride nanosheets to manganese chloride and dissolving it in deionized water, the mass volume ratio of manganese chloride to deionized water is 148.5 mg: 30~50 mL, recorded as solution B; then mixing solution A and solution B, adding tetramethylammonium hydroxide and hydrogen peroxide, stirring at a fifth temperature for a fourth preset time, then collecting the brown precipitate by centrifugation, washing three times with deionized water, washing three times with methanol, and drying the resulting product to obtain a zinc-doped graphene-phase carbon nitride-manganese dioxide heterojunction composite powder; Step 4. According to the third preset mass ratio, a certain amount of zinc-doped graphene phase carbon nitride-manganese dioxide heterojunction powder and polymer powder are weighed and evenly mixed, dispersed into dichloromethane with a fourth preset mass ratio to form a suspension, and then mixed with N,N-dimethylformamide and stirred for 3 hours, wherein the mass ratio of dichloromethane to N,N-dimethylformamide is 4:1, and finally, a zinc-doped graphene phase carbon nitride-manganese dioxide / polymer composite wound dressing is prepared by electrospinning technology.

2. The zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite wound dressing according to claim 1, characterized in that: In the step 4, the polymer powder is at least one of polylactic acid, polyglycolic acid, polylactic acid-hydroxyglycolic acid copolymer, polycaprolactone, and polydioxanone.

3. The zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite wound dressing according to claim 1, characterized in that: In the step 4, the particle size of the polymer powder is 40 to 60 μm, and the particle size of the zinc-doped graphene phase carbon nitride-manganese dioxide heterojunction composite powder is 4 to 10 μm.

4. The zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite wound dressing according to claim 1, wherein: In the step 1, the first temperature is 550° C., and the first preset time is 4 hours.

5. The zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite wound dressing according to claim 1, characterized in that: In the step 2, the second preset time is 30 min, the first preset mass ratio is 0.97:0.03, and the second temperature is 80°C.

6. The zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite wound dressing according to claim 1, characterized in that: In step three, the second preset mass ratio is 1.34:1, the fifth temperature is 25°C, and the fourth preset time is 12 h; the mass volume ratio of the zinc-doped graphene-phase carbon nitride nanosheets to tetramethylammonium hydroxide is 1 g:30 mL, the mass volume ratio of the zinc-doped graphene-phase carbon nitride nanosheets to hydrogen peroxide is 1 g:7.5 mL, and the hydrogen peroxide concentration is 60 mM; the centrifugal speed is 7000~8000 r / min, and the time is 4~6 min.

7. The zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite wound dressing according to claim 1, characterized in that: In the step 4, the third preset mass ratio is 1-20:80-99, and the fourth preset mass ratio is 0.4-0.6:4.32-7.

52.

8. The zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite wound dressing according to claim 1, characterized in that: In step 4, the electrospinning technology is used to prepare the wound dressing, and the obtained material is placed in an electrospinning system for spinning. The spinning machine voltage is 15-19 kV, the ambient temperature is 25-35 ° C, the humidity is 45-65%, the pushing speed is 0.007 mm / s, and the distance between the needle and the contact surface is 4 cm.

9. The zinc-doped graphene-phase carbon nitride-manganese dioxide / polymer composite wound dressing according to claim 1, characterized in that: The prepared zinc-doped graphene phase carbon nitride-manganese dioxide / polymer composite wound dressing is used as a new skin wound implant material.

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