S-type three-dimensional carbon nitride / copper sulfide nanosphere heterojunction and preparation method and application thereof

Abstract

The invention discloses an S-type three-dimensional carbon nitride / copper sulfide nanosphere heterojunction as well as a preparation method and application thereof, and belongs to the field of antibacterial application of nano materials. The three-dimensional porous carbon nitride not only can increase photocatalytic active sites, but also can improve close contact with copper sulfide. The copper sulfide nanospheres and the three-dimensional porous nanosheets construct an S-shaped heterojunction, and efficient separation of photo-induced electrons and hole pairs can be driven under the action of a built-in electric field, band edge bending and coulomb force. The S-type three-dimensional carbon nitride / copper sulfide nanosphere heterojunction can generate more active oxygen species to inactivate bacteria through a photocatalysis-Fenton-like reaction; in addition, the photothermal effect of copper sulphide has a certain auxiliary sterilization effect. Under the conditions of visible light irradiation and trace hydrogen peroxide, the inactivation rates of the S-type three-dimensional carbon nitride / copper sulfide nanosphere heterojunction on staphylococcus aureus and escherichia coli are up to 99.5% and 99.7% respectively, and meanwhile, the S-type three-dimensional carbon nitride / copper sulfide nanosphere heterojunction has a remarkable treatment effect on wounds infected by staphylococcus aureus.

Description

Technical Field

[0001] The present invention belongs to the technical field of antibacterial applications of nanomaterials, and particularly relates to an S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction and a preparation method and application thereof. Background Art

[0002] In recent years, bacterial infections caused by pathogenic microorganisms have posed a significant threat to the natural environment and human health. While antibiotics can effectively prevent and treat bacterial infections, their extensive use can lead to the emergence of drug-resistant bacteria and inactivate antibiotics. Therefore, the search for a simple, efficient, and environmentally friendly new sterilization technology is of great practical significance.

[0003] Photocatalytic technology based on semiconductor materials plays an important role in bacterial inactivation due to its broad inactivation potential and environmental friendliness. Carbon nitride, a two-dimensional semiconductor material composed of carbon and nitrogen, can generate reactive oxygen species with oxidative properties when exposed to visible light. These species can destroy bacterial cell membranes, proteins, lipids, and other intracellular substances, thereby inactivating the bacteria.

[0004] Although carbon nitride-based materials have broad application prospects in photocatalytic antibacterial applications, there are still many challenges, such as low light utilization efficiency, dependence on light, and limited concentration of reactive oxygen species generated. Summary of the Invention

[0005] In order to solve the above problems, in the first aspect, the present invention proposes a method for preparing an S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction, comprising the following steps: Cyanuric acid and melamine are subjected to supramolecular self-assembly in ultrapure water, and the obtained supramolecular self-assembly product is pre-freeze-dried after removing impurities, and then heated to a specific temperature and kept warm, and then cooled to obtain a three-dimensional porous carbon nitride nanosheet; A thioacetamide solution is added dropwise to a soluble copper salt solution, and the reaction is carried out in a water bath. The water bath reaction product is centrifuged, washed, and dried to obtain copper sulfide nanospheres. The amount of thioacetamide used in the present invention is not specifically limited. Generally, the amount of thioacetamide is more than twice the amount of the soluble copper salt solution.

[0006] Three-dimensional porous carbon nitride nanosheets and copper sulfide nanospheres are mixed in a mass ratio of 5:2-4, ethylene glycol is added for ultrasonic dispersion, and then a hydrothermal reaction is performed. The hydrothermal reaction product is centrifuged, washed, and dried to obtain an S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction. Specifically, the mass ratio of the three-dimensional porous carbon nitride nanosheets to the copper sulfide nanospheres is 5:2, 5:3, or 5:4, preferably 5:3.

[0007] Furthermore, the molar ratio of cyanuric acid to melamine is 1:0.5-2. Specifically, the molar ratio of cyanuric acid to melamine is 1:0.5, 1:1, 1:1.2, 1:1.8, 1:2, and preferably 1:1.

[0008] Furthermore, during the preparation of three-dimensional porous carbon nitride nanosheets, the temperature is raised to 520-580°C and then maintained for 3-5 hours. Specifically, the temperature can be raised to 520, 530, 535, 550, 570, 580°C, preferably 550°C; the holding time can be 3, 3.5, 4, 4.8, or 5 hours.

[0009] Furthermore, in the process of preparing copper sulfide nanospheres, the soluble copper salt is selected from one of copper nitrate, copper chloride, copper sulfate and copper acetate monohydrate.

[0010] Furthermore, the water bath temperature during the preparation of copper sulfide nanospheres is 80-100°C, specifically, 80, 85, 90, 95, or 100°C.

[0011] Furthermore, in the process of preparing the S-type three-dimensional carbon nitride / copper sulfide nanosphere heterojunction: The temperature of the hydrothermal reaction is 150°C-200°C; specifically, the temperature of the hydrothermal reaction can be 150, 160, 168, 175, 180, 196, or 200°C.

[0012] The holding time of the hydrothermal reaction is 20-28 hours; specifically, the holding time can be 20, 21, 24, or 28 hours.

[0013] The drying conditions are 50-70° C. and 12-24 h of drying time. Specifically, the drying temperature can be 50, 56, 60, 65, or 70° C.; and the drying time can be 12, 18, 20, or 24 h.

[0014] In a second aspect, the present invention proposes an S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction, wherein the heterojunction is composed of three-dimensional porous carbon nitride nanosheets and supported copper sulfide nanospheres; Copper sulfide nanospheres form an S-type heterojunction on the surface of three-dimensional porous carbon nitride nanosheets.

[0015] In a third aspect, the present invention proposes the use of the S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction in the preparation of an antibacterial agent for killing Gram-positive bacteria and / or Gram-negative bacteria.

[0016] In a fourth aspect, the present invention proposes the use of the S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction in the preparation of a drug for treating wound healing caused by Gram-positive bacteria and / or Gram-negative bacteria.

[0017] Furthermore, the drug performs antibacterial and / or wound healing activities through a photocatalytic-Fenton-like effect; specifically, the following processes are involved in exerting therapeutic effects: It produces photocatalytic antibacterial effect under visible light irradiation; Catalyzes hydrogen peroxide to produce a Fenton-like reaction in the wound microenvironment.

[0018] Beneficial effects of the present invention: The three-dimensional porous carbon nitride prepared by the present invention can not only increase the photocatalytic active sites, but also improve the close contact with copper sulfide; the narrow band gap characteristics of copper sulfide extend the light response range to the near-infrared region, and have a photothermal effect; the built-in electric field, band edge bending and Coulomb force of the S-type heterojunction can drive the efficient separation of photogenerated electron and hole pairs.

[0019] The S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction prepared by this invention can generate more reactive oxygen species through a photocatalytic Fenton-like reaction. Furthermore, the photothermal effect of copper sulfide has a certain auxiliary sterilization effect. Under visible light irradiation and trace amounts of hydrogen peroxide, the inactivation rates against Staphylococcus aureus and Escherichia coli reached 99.5% and 99.7%, respectively. The device is also effective in treating wounds infected with Staphylococcus aureus, and exhibits excellent biocompatibility and non-toxicity.

[0020] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 The X-ray diffraction patterns of the S-shaped three-dimensional porous carbon nitride / copper sulfide nanosphere heterojunction (SCN@CuS-2) material prepared in Example 2 of the present invention and the three-dimensional porous carbon nitride (SCN) and copper sulfide nanosphere (CuS) materials prepared in the comparative example are shown; Figure 2 The transmission electron microscope image of the SCN@CuS-2 material prepared in Example 2 of the present invention is shown; Figure 3The UV-visible absorption spectra of the SCN@CuS-2 material prepared in Example 2 of the present invention and the SCN and CuS materials prepared in the comparative example are shown; Figure 4 The Fourier transform infrared spectra of the SCN@CuS-2 material prepared in Example 2 of the present invention and the SCN and CuS materials prepared in the comparative example are shown; Figure 5 The steady-state photoluminescence spectra of the SCN@CuS-2 material prepared in Example 2 of the present invention and the SCN and CuS materials prepared in the comparative example are shown; Figure 6 The near-infrared thermal images of the SCN@CuS-2 material prepared in Example 2 and the SCN and CuS materials prepared in the comparative example are shown; Figure 7 The figures show the scanning electron microscopy and transmission electron microscopy comparison images of Staphylococcus aureus and Escherichia coli after sterilization in Example 1 of the present invention; wherein a and b respectively represent the scanning electron microscopy and transmission electron microscopy images of Staphylococcus aureus after the sterilization experiment of the SCN@CuS-2 group; c and d respectively represent the scanning electron microscopy and transmission electron microscopy images of Escherichia coli after the sterilization experiment of the SCN@CuS-2 group; Figure 8A The figure shows the plate coating of Staphylococcus aureus in each experimental group in Application Example 1 of the present invention; Figure 8B The antibacterial rate results of the materials in each experimental group against Staphylococcus aureus in Application Example 1 of the present invention are shown; Figure 8C The figure shows the plate coating diagram of Escherichia coli in each experimental group in Application Example 1 of the present invention; Figure 8D The results of the antibacterial rate of the materials in each experimental group against Escherichia coli in Example 1 of the present invention are shown; Figure 9A The results of using DMPO to capture superoxide radicals in the SCN@CuS-2 material prepared in Example 2 are shown; Figure 9B The results of using DMPO to capture hydroxyl radicals in the SCN@CuS-2 material prepared in Example 2 are shown; Figure 10 The results of in vivo antibacterial and wound healing experiments of SCN@CuS-2 prepared in Application Example 2 of the present invention are shown; Figure 11 The hemolysis rates of the S-type SCN@CuS-2 heterojunction prepared in Example 1 of the present invention at different concentrations are shown. DETAILED DESCRIPTION

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0024] Example 1 A method for preparing an S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction antibacterial agent comprises the following steps: (1) Weigh 5.04 g of cyanuric acid and 5.16 g of melamine, transfer them to a 250 mL beaker, add 135 mL of ultrapure water, and stir continuously at 400 r / min for 10 h at room temperature to allow the precursors to fully complex. Subsequently, the suspension was separated by centrifugation (8000 r / min, 10 min), and the precipitate was ultrasonically washed twice with deionized water to remove impurities. The precipitate was pre-frozen at low temperature and freeze-dried for 12 h to obtain a white dry powder. The powder was evenly ground and transferred to a 50 mL crucible. The temperature was raised to 550 °C at a rate of 5 °C / min and kept at this temperature for 4 h. The mixture was cooled to room temperature to obtain light yellow loose three-dimensional porous carbon nitride nanosheets (SCN).

[0025] (2) Weigh copper acetate monohydrate (200.0 mg, 1 mmol) and place it in a 100 mL beaker. Add 30 mL of ultrapure water and sonicate for half an hour. Dissolve thioacetamide (150.3 mg, 2 mmol) in 10 mL of ultrapure water. Heat the copper acetate in a 90°C water bath, slowly add the thioacetamide solution dropwise, and continue stirring in the water bath until the solution evaporates. Stop heating, centrifuge, wash, and dry to obtain black solid copper sulfide nanospheres (CuS). The amount of thioacetamide used in the present invention is not specifically limited. Generally, the amount of thioacetamide can be more than twice the amount of copper acetate monohydrate.

[0026] (3) 100 mg of SCN and 60 mg of CuS were placed in a 50 mL polytetrafluoroethylene hydrothermal reactor. 25 mL of ethylene glycol was added and ultrasonicated for 0.5 h, followed by stirring for 1 h. After completion, the reaction mixture was kept at 180 °C for 24 h. After cooling to room temperature, the product was centrifuged and washed, and dried at 60 °C overnight to obtain the S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction SCN@CuS, which was designated as SCN@CuS-1.

[0027] Example 2 A method for preparing an S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction antibacterial agent comprises the following steps: (1) Weigh 5.04 g of cyanuric acid and 5.16 g of melamine, transfer them to a 250 mL beaker, add 135 mL of ultrapure water, and stir continuously at 400 r / min for 10 h at room temperature to allow the precursors to fully complex. Subsequently, the suspension was separated by centrifugation (8000 r / min, 10 min), and the precipitate was ultrasonically washed twice with deionized water to remove impurities. The precipitate was pre-frozen at low temperature and freeze-dried for 12 h to obtain a white dry powder. The powder was evenly ground and transferred to a 50 mL crucible. The temperature was raised to 550 °C at a rate of 5 °C / min and kept at this temperature for 4 h. The mixture was cooled to room temperature to obtain light yellow loose three-dimensional porous carbon nitride nanosheets (SCN).

[0028] (2) Weigh copper acetate monohydrate (200.0 mg, 1 mmol) into a 100 mL beaker, add 30 mL of ultrapure water, and sonicate for half an hour. Dissolve thioacetamide (150.3 mg, 2 mmol) in 10 mL of ultrapure water. Heat the copper acetate in a 90°C water bath, slowly add the thioacetamide solution dropwise, and continue stirring in the water bath until the solution evaporates. Stop heating, centrifuge, wash, and dry to obtain black solid copper sulfide nanospheres (CuS).

[0029] (3) 100 mg of SCN and 40 mg of CuS were placed in a 50 mL polytetrafluoroethylene hydrothermal reactor. 25 mL of ethylene glycol was added and ultrasonicated for 0.5 h, followed by stirring for 1 h. The reaction mixture was then kept at 180°C for 24 h. After cooling to room temperature, the product was centrifuged, washed, and dried at 60°C overnight to obtain the product SCN@CuS, designated SCN@CuS-2.

[0030] Example 3 A method for preparing an S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction antibacterial agent comprises the following steps: (1) Weigh 5.04 g of cyanuric acid and 5.16 g of melamine, transfer them to a 250 mL beaker, add 135 mL of ultrapure water, and stir continuously at 400 r / min for 10 h at room temperature to allow the precursors to fully complex. Subsequently, the suspension was separated by centrifugation (8000 r / min, 10 min), and the precipitate was ultrasonically washed twice with deionized water to remove impurities. The precipitate was pre-frozen at low temperature and freeze-dried for 12 h to obtain a white dry powder. The powder was evenly ground and transferred to a 50 mL crucible. The temperature was raised to 550 °C at a rate of 5 °C / min and kept at this temperature for 4 h. The mixture was cooled to room temperature to obtain light yellow loose three-dimensional porous carbon nitride nanosheets (SCN).

[0031] (2) Weigh copper acetate monohydrate (200.0 mg, 1 mmol) into a 100 mL beaker, add 30 mL of ultrapure water, and sonicate for half an hour. Dissolve thioacetamide (150.3 mg, 2 mmol) in 10 mL of ultrapure water. Heat the copper acetate in a 90°C water bath, slowly add the thioacetamide solution dropwise, and continue stirring in the water bath until the solution evaporates. Stop heating, centrifuge, wash, and dry to obtain black solid copper sulfide nanospheres (CuS).

[0032] (3) 100 mg of SCN and 80 mg of CuS were placed in a 50 mL polytetrafluoroethylene hydrothermal reactor. 25 mL of ethylene glycol was added and ultrasonicated for 0.5 h, followed by stirring for 1 h. The reaction mixture was then kept at 180°C for 24 h. After cooling to room temperature, the product was centrifuged, washed, and dried at 60°C overnight to obtain the product SCN@CuS, designated SCN@CuS-3.

[0033] Comparative Example Loose and porous three-dimensional carbon nitride nanosheets (SCN) were prepared according to the method of step (1) in Example 1, and CuS was prepared according to the method of step (2) in Example 1.

[0034] Test Example 1 The crystal structures of SCN@CuS-2, SCN and CuS were analyzed by X-ray diffraction (XRD). Figure 1 As shown, it can be seen that SCN@CuS-2 has obvious characteristic peaks of SCN and characteristic peaks of hexagonal CuS, indicating that CuS is successfully loaded with SCN.

[0035] The microstructure of SCN@CuS-2 was observed by transmission electron microscopy (TEM). Figure 2 As shown in Figure 3, it can be seen that the SCN exhibits a 3D ultrathin nanosheet structure, and the CuS nanospheres are uniformly attached to the SCN nanosheets.

[0036] The light absorption properties of SCN, CuS and SCN@CuS-2 were tested by UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). Figure 3 As shown, it can be seen that SCN@CuS-2 shows a significant increase in absorption intensity in the long wavelength region (>500nm), which can promote the efficiency of light utilization.

[0037] Fourier transform infrared spectroscopy (FTIR) was used to analyze the chemical bonds and functional groups of SCN@CuS-2, SCN and CuS. Figure 4 As shown, CuS is at 620 cm -1 The characteristic peak of Cu-S bond appears at 810 cm -11200-1800cm -1 and 3000-3500cm -1 The SCN@CuS-2 spectrum contains the characteristic absorption bands of both CuS and SCN, and no new chemical bond signals appear, indicating that no other substances have been introduced.

[0038] Steady-state photoluminescence (PL) spectroscopy was used to test the recombination efficiency of photogenerated electron-hole pairs of SCN@CuS-2, SCN, and CuS. Figure 5 As shown in Figure 3, the fluorescence emission peak intensity of SCN@CuS-2 is significantly reduced compared with that of SCN, which indicates that CuS loading optimizes the photogenerated charge separation kinetics.

[0039] Photothermal imaging was used to analyze the temperature changes of SCN@CuS-2, SCN and CuS under visible light. Figure 6 As shown, it can be seen that the temperature of SCN@CuS-2 increased from 27.6 °C to 53.4 °C after 8 min of visible light irradiation, indicating that the photothermal effect in the antibacterial process helps to inactivate bacteria.

[0040] Application Example 1 An in vitro antibacterial experiment was conducted to evaluate the sterilization performance of the materials prepared in Preparation Examples 1-3 and the Comparative Example. The specific process is as follows: Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were selected as representatives of Gram-positive and Gram-negative bacteria, respectively. 1 mg of the test materials (SCN@CuS-1, SCN@CuS-2, SCN@CuS-3, CuS) were dispersed in 18 mL of PBS buffer, and then 2 mL of pretreated bacterial solution (3 × 10 7 CFU / mL), stir in the dark for 20 min.

[0041] 3mM H₂O₂ solution was then injected into each buffer system and immediately placed under a light source (λ > 420nm, 300W, 100mW / cm²) for antibacterial testing. Appropriate amounts of the reaction bacterial suspension were pipetted at regular intervals, applied in a gradient dilution pattern, and incubated at a constant temperature for 16 hours. Antibacterial activity was assessed by colony count on a plate.

[0042] Six groups were set up in the experiment, namely, light group, H2O2 group, CuS group, SCN@CuS-1 group, SCN@CuS-2 group, and SCN@CuS-3 group. The treatment methods of each experimental group are as follows: Illumination group: illumination only; H2O2 group: light + H2O2; CuS group: light + H2O2 + CuS; SCN@CuS-1 group: light+H2O2+SCN@CuS-1; SCN@CuS-2 group: light+H2O2+SCN@CuS-2; SCN@CuS-3 group: light+H2O2+SCN@CuS-3; All experiments were repeated three times. Before the experiment, all glassware and solutions were autoclaved at 121°C for 20 min. The bacteria in the SCN@CuS-2 group after sterilization were fixed and dehydrated, and then used for SEM and TEM analysis (e.g. Figure 7 (as shown in the figure), accurately observing the morphological changes of the bacteria. It is clearly visible that after the reaction, the edges of the membrane become shrunken and broken, indicating that its integrity and permeability are severely compromised. Significant shrinkage, depressions, and perforations are evident at the red arrows.

[0043] The calculation formula of antibacterial rate is as follows:

[0044] Among them, A represents the number of bacteria growing in the plate with the illumination time, and A0 represents the number of bacteria in the original plate.

[0045] The plates of Staphylococcus aureus and Escherichia coli in each experimental group were spread as follows Figure 8A and Figure 8C As shown in the figure, the antibacterial rates of each sample against Staphylococcus aureus and Escherichia coli were calculated by colony counting method. Under the same conditions, the antibacterial rate of 3mM H2O2 against Staphylococcus aureus was only 17.3%, while the bactericidal rates of CuS, SCN@CuS-1, SCN@CuS-2 and SCN@CuS-3 material systems against Staphylococcus aureus were 79.8%, 88.4%, 99.5% and 96.8% respectively at 8 minutes ( Figure 8B ). Similar to Staphylococcus aureus, the sterilization rates of pure light, H2O2, CuS, SCN@CuS-1, SCN@CuS-2 and SCN@CuS-3 material systems against Escherichia coli at 8 minutes were 4.5%, 19.1%, 84.3%, 85.3%, 99.7% and 97.1%, respectively. Figure 8D ).

[0046] Electron paramagnetic resonance (EPR) combined with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) was used to detect hydroxyl radicals (·OH) and superoxide anion radicals (·O2⁻) in the SCN@CuS-2 group. After the SCN@CuS-2 group system was mixed with DMPO solution (DMPO aqueous solution and DMPO methanol solution were used to detect ·OH and ·O2⁻, respectively), it was immediately transferred to the EPR quartz capillary for scanning. The results are shown in Figure 2. Figure 9A and Figure 9B As shown in Figure 2 , ·OH and ·O⁻ were detected in the SCN@CuS-2 system. ·O⁻ was generated during the photocatalytic process, while ·OH was produced by a Fenton-like reaction. Furthermore, a temperature increase indicated a photothermal effect. Taking these factors into account, the SCN@CuS-2 material system exhibits a synergistic sterilization effect of photocatalysis, Fenton-like reaction, and photothermal effect under the action of visible light and a low-concentration hydrogen peroxide solution.

[0047] Application Example 2 In vivo antibacterial experiments were conducted to evaluate the sterilization performance of the photocatalytic-Fenton-like-photothermal process of the materials prepared in Preparation Examples 1-3 and Comparative Examples. The specific process is as follows: Anesthesia was induced by inhalation anesthesia. A 1 cm puncture wound was created on the back of SPF male mice weighing about 20 g. 2 The wound was treated with Staphylococcus aureus (10 7 CFU / mL) was slowly dripped onto the wound surface. After 24 hours, wound infection could be observed, with redness, swelling, and yellow pus on the surface.

[0048] The successfully infected mice were randomly divided into five groups, and the mice that met the infection criteria were randomly divided into five groups (n=6 / group): negative control group (PBS buffer), H2O2 control group (3mM), SCN single group (50μg / mL), CuS single group (50μg / mL), and SCN@CuS-2 complex group (50μg / mL). 100μL of the corresponding preparation was topically administered daily, followed by irradiation with a xenon lamp light source (>420nm, 100mW / cm²) for 10min, and the intervention lasted for 8 consecutive days.

[0049] A digital camera was used to record the changes in wound surface area. The pictures and morphology of the mouse wounds on days 0, 3, 6, and 8 after intervention with PBS, H2O2, CuS, SCN, and SCN@CuS-2 are shown in the figure below. Figure 10 After 8 days of treatment, the wound conditions of all mice improved overall, with the wound area of ​​the SCN@CuS-2 group decreasing most significantly.

[0050] Application Example 3 The hemolysis rate of S-type SCN@CuS-2 heterojunctions at different concentrations was tested. Mouse blood was centrifuged to collect red blood cells (RBCs) and resuspended in PBS. 20µL of the RBC suspension was then added to each test sample (380µL), vortexed, and incubated at 37°C for 2 hours. The supernatant was transferred to a 96-well plate, and the absorbance at 570nm was measured. The results are shown in Figure 2. Figure 11 As shown in the figure, the EP tubes from left to right correspond to 0.01 mg mL -1 SCN@CuS-2, 0.5 mg mL-1 SCN@CuS-2, 1 mg mL -1 SCN@CuS-2, PBS buffer and ultrapure water. It can be seen that the S-type SCN@CuS-2 heterojunctions at different concentrations are non-toxic to blood.

[0051] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction, characterized in that: The following steps are involved: Cyanuric acid and melamine are subjected to supramolecular self-assembly in ultrapure water, and the obtained supramolecular self-assembly product is pre-freeze-dried after removing impurities, and then heated to a specific temperature and kept warm, and then cooled to obtain a three-dimensional porous carbon nitride nanosheet; Adding thioacetamide solution dropwise to a soluble copper salt solution, reacting in a water bath, centrifuging the water bath reaction product, washing, and drying to obtain copper sulfide nanospheres; Three-dimensional porous carbon nitride nanosheets and copper sulfide nanospheres are mixed in a mass ratio of 5:2-4, ethylene glycol is added for ultrasonic dispersion, and then a hydrothermal reaction is carried out. The hydrothermal reaction product is centrifuged, washed and dried to obtain an S-type three-dimensional carbon nitride / copper sulfide nanosphere heterojunction.

2. The method for preparing an S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction according to claim 1, characterized in that: The molar ratio of cyanuric acid to melamine is 1:0.5-2.

3. The method for preparing an S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction according to claim 1, characterized in that: During the preparation of three-dimensional porous carbon nitride nanosheets, the temperature is raised to 520-580°C and then maintained for 3-5 hours.

4. The method for preparing an S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction according to claim 1, characterized in that: In the process of preparing copper sulfide nanospheres, the soluble copper salt is selected from one of copper nitrate, copper chloride, copper sulfate and copper acetate monohydrate.

5. The method for preparing an S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction according to claim 1, characterized in that: The water bath temperature during the preparation of copper sulfide nanospheres is 80-100°C.

6. The method for preparing an S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction according to claim 1, characterized in that: During the preparation of S-type three-dimensional carbon nitride / copper sulfide nanosphere heterojunction: The temperature of the hydrothermal reaction is 150°C-200°C; The holding time of the hydrothermal reaction is 20-28h; The drying conditions are a temperature of 50-70°C and a drying time of 12-24 hours.

7. An S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction, characterized in that: Prepared by the preparation method according to any one of claims 1 to 6, the heterojunction consists of a three-dimensional porous nanosheet structure and copper sulfide nanospheres supported on the surface of the three-dimensional porous nanosheet; Copper sulfide nanospheres form an S-type heterojunction on the surface of three-dimensional porous nanosheets.

8. Use of the S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction according to claim 7 in the preparation of an antibacterial agent for killing Gram-positive bacteria and / or Gram-negative bacteria.

9. Use of the S-shaped three-dimensional carbon nitride / copper sulfide nanosphere heterojunction according to claim 7 in the preparation of a drug for treating wounds caused by Gram-positive bacteria and / or Gram-negative bacteria.

10. The use according to claim 9, characterized in that The drug has antibacterial and / or wound healing promoting effects through a photocatalytic-Fenton-like effect.

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