Antibacterial agent based on graphite-phase carbon nitride as well as preparation method and application of antibacterial agent

Abstract

The invention belongs to the technical field of photocatalytic materials, and particularly relates to an antibacterial agent based on graphite-phase carbon nitride and a preparation method and application thereof.The surface of graphite-phase carbon nitride is wrapped with hyaluronic acid to obtain C3N4 / HA, and then an antibacterial agent is loaded to obtain the antibacterial agent. According to the antibacterial agent, hyaluronidase is consumed by modifying hyaluronic acid, the compactness of a drug-resistant bacterium biological membrane is reduced, and an antibacterial drug can be responsively released; the biological membrane is further destroyed by utilizing the special structure of graphite-phase carbon nitride, efficient sterilization is performed through a photocatalytic therapy and a chemical therapy in combination with an antibacterial drug under light mediation, new resistance of drug-resistant bacteria is effectively avoided, and the composite material can be used for treating wound infection caused by bacteria and has further popularization value.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials technology, specifically relating to an antibacterial agent based on graphitic carbon nitride, its preparation method, and its application. Background Technology

[0002] As a vital protective barrier, the skin blocks external environmental factors, resists bacterial invasion, and buffers physical and chemical stimuli. When the skin, muscles, or mucous membranes are damaged, leading to disruption or loss of tissue integrity, a wound is formed. Wound healing typically involves four stages: hemostasis and coagulation, inflammatory response, cell migration and proliferation, and tissue remodeling. It is often accompanied by bacterial invasion, which can lead to wound infection, interfere with skin tissue repair, delay wound healing, and in severe cases, cause persistent infection at the wound site, potentially leading to systemic infection and significantly increasing the patient's morbidity and mortality risk.

[0003] Clinically, high-dose antibiotics are commonly used to treat early-stage bacterial wound infections, resulting in a relatively good prognosis. However, overuse of antibiotics leads to decreased bacterial sensitivity and even drug resistance, significantly reducing the effectiveness of antibiotic therapy. Furthermore, during infection, free bacteria adhere to the wound surface, secreting extracellular polymers such as polysaccharide matrices, lipid proteins, and fibrin, encapsulating them to form a biofilm. This biofilm, with its unique structure and microenvironment (e.g., hypoxia, nutrient deprivation, and low metabolism), greatly reduces bacterial sensitivity to the environment. This not only further enhances drug resistance within the biofilm but also significantly reduces the penetration and retention of antibiotics, leading to poor antibiotic efficacy. Simultaneously, repeated infections during treatment increase wound secretions, further worsening the condition.

[0004] Graphitic carbon nitride (g-C3N4), as a novel two-dimensional nanomaterial, possesses a sharp, sheet-like structure that can disrupt the integrity of biofilms. It also exhibits excellent visible light responsiveness, undergoing photocatalytic reactions under light to generate reactive oxygen species (ROS), causing irreversible damage to biomolecules within drug-resistant bacteria and achieving photocatalytic antibacterial efficacy without easily inducing new bacterial resistance. However, g-C3N4 alone suffers from poor water solubility, poor biocompatibility, lack of targeting, and a tendency to aggregate in vivo, limiting its clinical translational applications.

[0005] Hyaluronic acid (HA) is a natural polysaccharide with good biocompatibility and biodegradability. It can specifically bind to the CD44 receptor, which is highly expressed on the surface of tumor cells and cells in inflammatory sites, to achieve targeted delivery. At the same time, hyaluronic acid can be degraded by hyaluronidase to achieve enzyme-responsive drug release. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention proposes an antibacterial agent based on graphite-phase carbon nitride, its preparation method, and its application. It utilizes hyaluronic acid to consume hyaluronidase (HAase) within the biofilm of drug-resistant bacteria, achieving responsive release of the antibacterial drug. The structure of graphite-phase carbon nitride disrupts the biofilm, enhancing drug penetration and accumulation within it. Furthermore, it rapidly kills bacteria through a combination of phototherapy and photocatalytic therapy mediated by light, promoting the repair of infected tissues.

[0007] The technical solution adopted in this invention: An antibacterial agent based on graphitic carbon nitride, characterized in that the antibacterial agent comprises graphitic carbon nitride nanosheets as the core material, first coating the surface of the graphitic carbon nitride nanosheets with hyaluronic acid to obtain C3N4 / HA nanoparticles, and then loading antibacterial drugs onto the surface of the C3N4 / HA nanoparticles.

[0008] In one optional embodiment, the hyaluronic acid has a molecular weight range of 10. 3 ~10 7 Da.

[0009] In one optional embodiment, the mass ratio of hyaluronic acid to graphitic carbon nitride is (1~10):1.

[0010] In one optional embodiment, the mass ratio of the graphitic carbon nitride to the antibacterial drug is (5~20):1.

[0011] In one optional embodiment, the antibacterial drug is a drug with broad-spectrum bactericidal activity against Gram-negative and Gram-positive bacteria, including but not limited to at least one of clarithromycin, rifampin (abbreviated as Rif), metronidazole, and azithromycin.

[0012] The present invention also provides a method for preparing the aforementioned antibacterial agent, comprising the following steps: S1: Add graphitic carbon nitride to hyaluronic acid aqueous solution, sonicate for 0.5-5 h, centrifuge to collect the supernatant, filter to obtain C3N4 / HA nanoparticle suspension; S2: Dissolve the antibacterial drug in dimethyl sulfoxide (DMSO) to obtain an antibacterial drug solution. Add the antibacterial drug solution to a C3N4 / HA nanoparticle suspension to obtain a nanoparticle suspension loaded with the antibacterial drug. Remove the free antibacterial drug from the suspension to obtain the antibacterial agent.

[0013] The present invention also provides the use of the aforementioned antibacterial agent in the preparation of a medicament for treating wound infections caused by drug-resistant bacteria.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The hyaluronic acid layer of the antibacterial agent provided by the present invention can consume hyaluronidase in the biofilm of drug-resistant bacteria, reduce the compactness of the biofilm, and responsively release the antibacterial drug dispersed on the surface in the form of nanoparticles. Then, the graphitic carbon nitride with a sharp sheet-like structure is exposed, which can further destroy the integrity of the biofilm structure, form pores of various shapes, and promote the further accumulation of drugs in infected tissues.

[0015] 2. After the antibacterial agent of the present invention is enriched in the biofilm, the graphitic carbon nitride will catalyze the oxygen in the surrounding environment to undergo a photochemical reaction to generate ROS after being irradiated by a laser of a certain wavelength. This causes irreversible damage to the biomolecules of drug-resistant bacteria. When used in combination with antibacterial drugs, drug-resistant bacteria can be quickly killed by combining photocatalytic therapy with chemical therapy, completely disintegrating the biofilm and effectively preventing the emergence of new resistance in drug-resistant bacteria.

[0016] 3. This invention facilitates long-distance transportation and long-term storage of drugs, and it can be directly applied to the treatment of infected wounds. It is simple to operate, has significant efficacy, and has value for further promotion. Attached Figure Description

[0017] Figure 1 The particle size and potential diagrams of g-C3N4 and Rif@C3N4 / HA of the present invention are shown. Figure 2 This is a comparison chart of the particle sizes of metronidazole@C3N4 / HA, clarithromycin@C3N4 / HA, and azithromycin@C3N4 / HA of the present invention; Figure 3 Transmission electron microscope (TEM) images of g-C3N4 and Rif@C3N4 / HA of the present invention; Figure 4 Stability comparison of C3N4 / HA prepared for HA of different molecular weights; Figure 5 This is a drug release curve of Rif@C3N4 / HA according to the present invention; Figure 6 A comparison of fluorescence intensities of g-C3N4, C3N4 / HA, and Rif@C3N4 / HA under laser irradiation; Figure 7 The biofilm removal effects of HA, Rif, g-C3N4, C3N4 / HA and Rif@C3N4 / HA are shown in the figure. Figure 8 Image showing the effect of HA, Rif, g-C3N4, C3N4 / HA and Rif@C3N4 / HA on the area of ​​wound infection treated with drug-resistant bacteria; Figure 9The graph shows the changes in hyaluronidase content in wounds infected with drug-resistant bacteria after treatment with HA, Rif, g-C3N4, C3N4 / HA, and Rif@C3N4 / HA, respectively. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be further described clearly and completely below with reference to the accompanying drawings. It should be noted that the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0019] To make the inventive objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be further described in detail below with reference to the accompanying drawings: In order to better understand the above-mentioned objectives, features, and advantages of this invention, the advantages of this invention will be further illustrated below by comparing the embodiments with the accompanying drawings and specific implementation methods.

[0020] I. Preparation of Antibacterial Agents Based on Graphite Phase Carbon Nitride

[0021] Example 1 400mg HA (molecular weight: 10) 3 Add Da to 20 mL of deionized water to obtain an aqueous solution of HA.

[0022] 400 mg g-C3N4 was added to an HA aqueous solution and sonicated in a cell sonicator at 4°C and 100 W for 2 h (2 s sonication per 4 s interval). The supernatant was then collected by high-speed centrifugation. The supernatant was filtered through a microporous membrane to remove unbound material, yielding a C3N4 / HA nanosuspension.

[0023] Weigh 20 mg of Rif and dissolve it in 2 mL of DMSO to prepare a 10 mg / mL Rif solution, which is then refrigerated for later use. Add 400 μL of Rif to a 2 mL C3N4 / HA nanoparticle suspension, and remove the free drug by passing it through a G-25 dextran gel column to obtain Rif@C3N4 / HA.

[0024] Example 2 100mg HA (molecular weight: 10) 7 Add Da to 100 mL of deionized water to obtain an aqueous solution of HA.

[0025] 10 mg g-C3N4 was added to an HA aqueous solution and sonicated for 4 h at 4 °C and 200 W in a cell sonicator (2 s per sonication, with a 4 s interval). The supernatant was then collected by high-speed centrifugation. The supernatant was filtered through a microporous membrane to remove unbound material, yielding a C3N4 / HA nanosuspension.

[0026] Weigh 10 mg of metronidazole and dissolve it in 10 mL of DMSO to prepare a 1 mg / mL metronidazole solution, which is then refrigerated for later use. Add 200 μL of metronidazole to 10 mL of C3N4 / HA nanoparticle suspension, and remove the free drug by passing it through a G-25 dextran gel column to obtain metronidazole@C3N4 / HA.

[0027] Example 3 200mg HA (molecular weight: 10) 4 Add Da to 20 mL of deionized water to obtain an aqueous solution of HA.

[0028] 40 mg g-C3N4 was added to an HA aqueous solution and sonicated in a cell sonicator at 4°C and 300 W for 0.5 h (2 s sonication per 4 s interval). The supernatant was then collected by high-speed centrifugation. The supernatant was filtered through a microporous membrane to remove unbound material, yielding a C3N4 / HA nanosuspension.

[0029] Weigh 40 mg of clarithromycin and dissolve it in 10 mL of DMSO to prepare a 4 mg / mL clarithromycin solution, which is then refrigerated for later use. Add 30 μL of clarithromycin to 1 mL of C3N4 / HA nanoparticle suspension, and remove the free drug by passing it through a G-25 dextran gel column to obtain clarithromycin@C3N4 / HA.

[0030] Example 4 50 mg of HA (molecular weight: 10) 6 Add Da to 10 mL of deionized water to obtain an aqueous solution of HA.

[0031] 20 mg g-C3N4 was added to an HA aqueous solution and sonicated for 1.5 h at 4 °C and 200 W in a cell sonicator (2 s per sonication, with a 4 s interval). The supernatant was then collected by high-speed centrifugation. The supernatant was filtered through a microporous membrane to remove unbound material, yielding a C3N4 / HA nanosuspension.

[0032] Weigh 20 mg of azithromycin and dissolve it in 10 mL of DMSO to prepare a 2 mg / mL azithromycin solution, which is then refrigerated for later use. Add 50 μL of azithromycin to 1 mL of C3N4 / HA nanoparticle suspension, and remove the free drug by passing it through a G-25 dextran gel column to obtain azithromycin@C3N4 / HA.

[0033] Comparative Example 1 HA has a molecular weight of 10. 2 Da, the other steps are the same as in Example 1.

[0034] Comparative Example 2 HA has a molecular weight of 10. 8 Da, the other steps are the same as in Example 1.

[0035] II. Performance testing and efficacy testing of antibacterial agents

[0036] 1. Particle size and potential characterization determination g-C3N4, as well as Rif@C3N4 / HA obtained in Example 1, metronidazole@C3N4 / HA obtained in Example 2, clarithromycin@C3N4 / HA obtained in Example 3, and azithromycin@C3N4 / HA obtained in Example 4, were diluted with deionized water to form a suspension with a graphitic carbon nitride concentration of 10 μg / mL. Then, their particle size and zeta potential were measured at 25 °C.

[0037] Figure 1 Particle size and potential diagrams for g-C3N4 and Rif@C3N4 / HA are shown below. Figure 1 As shown, the particle sizes of g-C3N4 and Rif@C3N4 / HA are 180.3±7.4 nm and 211.7±3.1 nm, respectively; the potential of g-C3N4 is -11.4±2.1 mV, and the potential of Rif@C3N4 / HA is -32.2±1.4 mV. The results indicate that the particle size of Rif@C3N4 / HA is increased compared to g-C3N4. This is because HA forms a hydration layer on the outer surface of g-C3N4, and the drug loading also increases the hydration particle size. Furthermore, the HA-modified g-C3N4 surface has a large number of ionized carboxyl groups, exhibiting a strong negative charge, thus the potential value of Rif@C3N4 / HA is lower than that of g-C3N4, indicating successful HA modification.

[0038] Figure 2 The particle size comparison chart shows that of metronidazole@C3N4 / HA, clarithromycin@C3N4 / HA, and azithromycin@C3N4 / HA is as follows. Figure 2 As shown, the particle sizes of metronidazole@C3N4 / HA, clarithromycin@C3N4 / HA, and azithromycin@C3N4 / HA are 320.9±3.7 nm, 496.3±5.2 nm, and 663.1±12.4 nm, respectively. This indicates that the particle size of the antibacterial agent obtained in this invention is between 210 and 700 nm.

[0039] 2. Morphological determination g-C3N4 and Rif@C3N4 / HA obtained according to Example 1 were dropped onto the surface of a copper mesh, dried, and then their morphology was measured under a transmission electron microscope.

[0040] Figure 3 The images show transmission electron microscopy (TEM) images of g-C3N4 and Rif@C3N4 / HA, with image a being an TEM image of g-C3N4 and image b being an TEM image of Rif@C3N4 / HA. Image a shows that g-C3N4 exhibits a two-dimensional sheet-like structure with surface wrinkles, which is conducive to disrupting the integrity of biofilms. Combined with image b, it can be seen that the surface morphology of Rif@C3N4 / HA is similar to that of g-C3N4, indicating that encapsulating HA and loading antibacterial drugs did not significantly alter the structure of g-C3N4.

[0041] 3. Stability Test g-C3N4 and C3N4 / HA-10 prepared in Example 3 were compared. 4 C3N4 / HA-10 prepared in Comparative Example 1 2 C3N4 / HA-10 prepared in Comparative Example 2 8 The particles were diluted with PBS to the same concentration (C3N4 concentration was 20 μg / mL), and the particle size distribution was measured at the initial time and 48 hours later. The results are shown in Table 1.

[0042] Table 1. Particle size distribution (nm) of C3N4 / HA prepared from g-C3N4 and HA of different molecular weights.

[0043] As shown in Table 1, the initial particle size of g-C3N4 was only 180.3 nm, but it increased to 381.9 nm after 48 hours, which was an excessive increase. Using molecular weights of 10... 3 10 7 10 4 and 10 6 The C3N4 / HA prepared by Da showed a particle size that was almost identical to the initial size after 48 hours; while the particle size obtained by using a molecular weight of 10... 2 The C3N4 / HA obtained from Da showed a 70% increase in particle size after 48 hours, using a molecular weight of 10. 8 The particle size of C3N4 / HA obtained from Da's HA increased by 46% after 48 hours.

[0044] Figure 4 Stability test chromatograms of C3N4 / HA prepared for different molecular weights are shown below. Figure 4 As shown, unmodified g-C3N4 readily aggregates in PBS solution, exhibiting poor stability; HA with different molecular weights (molecular weight: 10) was used. 2 10 4 and 10 8 After modification, C3N4 / HA-10 is obtained. 2 C3N4 / HA-104 and C3N4 / HA-10 8 The initial average particle size of all three was approximately 210 nm; after storage in PBS solution for 48 h, C3N4 / HA-10 2 and C3N4 / HA-10 8 The average particle size has increased to around 350 nm. Unstable particle size can lead to loss of colloidal stability, non-specific drug leakage, and uncontrolled drug release. It can also cause aggregate accumulation toxicity, hindering subsequent research and clinical translation. Meanwhile, C3N4 / HA-10... 4 The average particle size remained stable, still around 210 nm after 48 hours.

[0045] The results showed that selecting molecules with a molecular weight of 10 3 ~10 7 C3N4 / HA prepared from HA within the Da range can provide g-C3N4 with extremely strong anti-agglomeration ability and improve the solution stability of the drug.

[0046] 4. Drug release test The Rif@C3N4 / HA (Rif concentration of 1 mg / mL) obtained in Example 1 was resuspended in phosphate buffer and phosphate buffer containing HAase (100 mg / mL), respectively, with a pH of 5.5. The solutions were placed in a shaker and shaken (100 rpm / min). Samples were then taken at 0, 2, 4, 8, 12, 24, and 48 hours, and the absorbance of the samples at 477 nm was detected using a spectrometer to calculate the drug release behavior.

[0047] Figure 5 The drug release curve for Rif@C3N4 / HA is shown below. Figure 5 It is evident that in the HAase-free medium, only a small amount of Rif@C3N4 / HA is released; in the HAase-containing medium, the concentration of Rif increases with the extension of incubation time, and the cumulative release of Rif reaches 29.6% and 59.4% at 2 and 24 hours, respectively. This is because HAase can degrade HA, which is beneficial for the release of antibacterial drugs and the killing of pathogens.

[0048] 5. Photocatalytic performance test 5 mL of g-C3N4 and the C3N4 / HA and Rif@C3N4 / HA obtained in Example 1 were thoroughly mixed with 100 μL of singlet oxygen green fluorescent probe SOSG (5 μM) reagent. The mixture was irradiated with a 440 nm laser for 3 min, and then the release behavior of reactive oxygen species was detected by fluorescence spectroscopy. The excitation wavelength was 504 nm and the generation wavelength was 525 nm.

[0049] Figure 6The image shows the photocatalytic effect of Rif@C3N4 / HA under laser irradiation, as follows: Figure 6 As shown, the g-C3N4 group showed no obvious fluorescence signal without laser irradiation; after 3 minutes of irradiation with a 440nm laser, the g-C3N4, C3N4 / HA, and Rif@C3N4 / HA groups all showed obvious fluorescence signals, and the fluorescence intensities among the three were similar, indicating that the surface-modified HA and the antibacterial drug-loaded Rif@C3N4 / HA effectively maintained the photocatalytic performance of g-C3N4.

[0050] 6. Anti-biofilm effect test Methicillin-resistant Staphylococcus aureus (MRSA) bacterial suspension (10 9 CFU / mL was mixed with TSB medium at a ratio of 1:100 and added to a 24-well plate, and incubated at 37°C for 12 h. Unattached bacteria were gently washed three times with sterile PBS to harvest the MRSA biofilm. Then, PBS, HA, Rif, g-C3N4, and C3N4 / HA and Rif@C3N4 / HA (Rif concentration 10 μg / mL) obtained in Example 1 were added to the wells. After adding the drugs, the plates were incubated at 37°C for 1 h, followed by blue light irradiation for 30 min. Subsequently, 200 μL of 1% crystal violet dye was added to each well for staining for 30 min, followed by washing three times with PBS and drying at 37°C. 200 μL of 33% glacial acetic acid was added to each well. Finally, the absorbance was measured at 595 nm to quantitatively analyze the biofilm ablation effect. The formula for calculating the biofilm clearance rate is:

[0051] Figure 7 The biofilm removal effects of HA, Rif, g-C3N4, C3N4 / HA, and Rif@C3N4 / HA are shown in the figure. Figure 7As shown, at the same dosage, HA had almost no anti-biofilm effect; free drug Rif could not efficiently penetrate the biofilm, resulting in a low drug concentration within the biofilm and failing to exert its excellent bactericidal effect, with a biofilm clearance rate of only 14.3%, which was unsatisfactory; g-C3N4, due to its sharp, plate-like structure, could disrupt the integrity of the biofilm, increasing its accumulation within the biofilm, and under light conditions, it would undergo a photocatalytic reaction to generate a large amount of ROS, thereby killing drug-resistant bacteria, achieving a biofilm clearance rate of 37.1%; C3N4 / HA can enhance drug accumulation by consuming hyaluronidase within the biofilm, and then ablate the biofilm under light-mediated irradiation, achieving a clearance rate of 45.9%. Compared with free HA and g-C3N4, the biofilm clearance ability is significantly improved, indicating that modifying g-C3N4 surface with HA can achieve a synergistic effect. Compared with free drugs Rif, g-C3N4 and C3N4 / HA, Rif@C3N4 / HA combined with chemotherapy and photocatalytic therapy under blue light irradiation can efficiently clear MRSA biofilms, with a clearance rate of over 92%.

[0052] 7. Efficacy test of treatment for drug-resistant bacterial wound infections To induce neutropenia in mice, cyclophosphamide (150 mg / kg) was injected intraperitoneally for three consecutive days before establishing the wound infection model. Mice were anesthetized with 4% chloral hydrate (40 mg / kg), their backs were shaved and prepared, and after alcohol disinfection, a circular wound approximately 5 mm in diameter was created. 50 μL of MRSA (10 mg / kg) was then instilled into the wound. 7 A wound infection model was constructed using bacterial suspensions containing CFU / mL. The bacteria were then treated with PBS, HA, Rif, g-C3N4, and C3N4 / HA and Rif@C3N4 / HA (Rif concentration 10 μg / mL) obtained in Example 1, respectively, and then subjected to blue light (10 mW / cm²). 2 Irradiate for 30 minutes, and monitor the wound healing of mice after treatment.

[0053] Figure 8 The image shows the therapeutic effects of HA, Rif, g-C3N4, C3N4 / HA, and Rif@C3N4 / HA on wound infections caused by drug-resistant bacteria. Figure 8As shown, the infected wounds of mice in the PBS and HA groups healed slowly, with more than 75% of the wound area remaining after 14 days of treatment. After treatment with free Rif and light-mediated g-C3N4 and C3N4 / HA, the healing effect of the infected wounds was significantly better than that of the PBS group. This is because both chemotherapy and photocatalytic therapy can kill some drug-resistant bacteria, thereby promoting the healing of infected wounds. Compared with other groups, mice treated with Rif@C3N4 / HA showed the best wound healing effect, with a wound healing rate of >90% at the end of treatment. This is because under light conditions, Rif@C3N4 / HA can work synergistically with photocatalytic therapy and chemotherapy to kill pathogens, disintegrate the biofilm of drug-resistant bacteria, and thus accelerate the repair of infected wounds.

[0054] 8. Hyaluronidase content test in infected tissue Mice with MRSA wound infection were treated with PBS, HA, Rif, g-C3N4, and C3N4 / HA and Rif@C3N4 / HA (Rif concentration 10 μg / mL) obtained in Example 1, respectively, and then subjected to blue light (10 mW / cm²). 2 Irradiation for 30 minutes, and on the 2nd and 7th day after treatment, infected tissue around the wound was collected, and the HAase content in the infected tissue was monitored using an ELISA kit.

[0055] Figure 9 The graph shows the changes in hyaluronidase content in wounds infected with drug-resistant bacteria after treatment with Rif@C3N4 / HA. On day 2 after treatment, the HAase content in the infected tissues of mice in the C3N4 / HA + light irradiation group and the Rif@C3N4 / HA + light irradiation group was much lower than that in the PBS, HA, Rif, and g-C3N4 + light irradiation groups, indicating that C3N4 / HA and Rif@C3N4 / HA can significantly reduce the level of HAase in infected tissues. On day 7 after treatment, although the HAase content in the C3N4 / HA + light irradiation group was still lower than that in other groups, it increased significantly. The HAase content in the Rif@C3N4 / HA + light irradiation group remained at around 4 ng / mg tissue, without a significant upward trend. This is because the combination of laser-mediated chemotherapy and photocatalytic therapy rapidly kills pathogens, effectively avoids the generation of new HAase, and is conducive to promoting the repair and healing of infected wounds.

[0056] The results showed that modifying the surface of g-C3N4 with HA can consume HAase in the biofilm of drug-resistant bacteria, significantly improving the ability to clear biofilms while maintaining photocatalytic performance, thus synergistically enhancing antibacterial ability. After loading with drugs, the ability to clear biofilms and treat wound infections was significantly enhanced. Under laser-mediated combined chemotherapy and photocatalytic therapy, pathogens were quickly killed, and the generation of new HAases was effectively avoided, which is conducive to promoting the repair and healing of infected wounds.

[0057] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0058] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. An antibacterial agent based on graphitic carbon nitride, characterized in that, The antibacterial agent comprises graphite-phase carbon nitride nanosheets as the core material. First, hyaluronic acid is coated on the surface of the graphite-phase carbon nitride nanosheets to obtain C3N4 / HA nanoparticles, and then antibacterial drugs are loaded on the surface of the C3N4 / HA nanoparticles.

2. The antibacterial agent according to claim 1, characterized in that, The molecular weight range of the hyaluronic acid is 10. 3 ~10 7 Da.

3. The antibacterial agent according to claim 1, characterized in that, The mass ratio of hyaluronic acid to graphitic carbon nitride is (1~10):

1.

4. The antibacterial agent according to claim 1, characterized in that, The mass ratio of the graphitic carbon nitride to the antibacterial drug is (5~20):

1.

5. The antibacterial agent according to claim 1, characterized in that, The antibacterial drug is a drug with broad-spectrum bactericidal activity against Gram-negative and Gram-positive bacteria, including but not limited to at least one of clarithromycin, rifampin, metronidazole, and azithromycin.

6. A method for preparing the antibacterial agent according to claim 1, characterized in that, Includes the following steps: S1: Add graphitic carbon nitride to hyaluronic acid aqueous solution, sonicate for 0.5-5 h, centrifuge to collect the supernatant, filter to obtain C3N4 / HA nanoparticle suspension; S2: Dissolve the antibacterial drug in dimethyl sulfoxide to obtain an antibacterial drug solution. Add the antibacterial drug solution to a C3N4 / HA nanoparticle suspension to obtain a drug-loaded nanoparticle suspension. Remove the free antibacterial drug from the suspension to obtain the antibacterial agent.

7. The use of the antibacterial agent as described in claim 1 in the preparation of a medicament for treating wound infections caused by drug-resistant bacteria.

Images