Single-layer wmos2 nanosheet and preparation method and application thereof

Abstract

The application belongs to the field of antibacterial two-dimensional nanomaterial Mxene catalysts, and particularly relates to a monolayer W@MoS2 nanosheet as well as a preparation method and application thereof. The method comprises the following steps: 1) dissolving water-soluble molybdate and water-soluble tungstate in water to obtain a mixed solution; 2) adding a sulfur source and an organic solvent to the mixed solution, and then performing reaction after mixing, and drying to obtain a powder. The monolayer W@MoS2 nanosheet has a unique two-dimensional planar structure, a large specific surface area, and good optical and electronic properties, and has high light-heat absorption in the near-infrared two region, i.e., the light-heat conversion efficiency is improved. Meanwhile, the peroxidase-like activity of the monolayer W@MoS2 nanosheet material realizes efficient light-heat amplification, can treat methicillin-resistant Staphylococcus aureus infection, and avoids heat therapy damage to normal tissues.

Description

Technical Field

[0001] This invention belongs to the field of antibacterial two-dimensional nanomaterials and Mxene catalysts, specifically relating to a single-layer W@MoS2 nanosheet, its preparation method, and its application. Background Technology

[0002] Research has revealed that Staphylococcus aureus is an infectious pathogen. Although it does not cause cellular infection, it can cause local and systemic purulent infections after entering the human circulatory system. In particular, methicillin-resistant Staphylococcus aureus (MRSA) was discovered in the 1960s. MRSA contains PBP2a, a unique characteristic of drug-resistant strains, enabling it to develop resistance to penicillin. PBP2a can be induced by β-lactam antibiotics and has a low affinity for them, thus rarely binding to these antibiotics. MRSA is ubiquitous, posing a significant challenge to effective medical treatment and infection control, making the eradication of the increasingly serious MRSA problem crucial. However, traditional antibiotic therapy has proven to have serious limitations. The World Health Organization has recognized the significant threat posed by drug-resistant bacteria to human health because these pathogens can spread rapidly and are difficult to control. Therefore, finding a new approach to treat drug-resistant bacterial infections is essential.

[0003] Photothermal therapy (PTT) is an innovative antibacterial method that uses near-infrared (NIR) light-induced photothermal agents (PTAs) to raise the temperature of bacteria and kill them. This method is characterized by being non-toxic, controllable, highly specific, and having few side effects. However, high-power treatment may damage surrounding cells and tissues, while low-power treatment can reduce the antibacterial effect. Therefore, those skilled in the art are focusing their research on novel antimicrobial materials.

[0004] Among antimicrobial materials, inorganic nanoparticles exhibit unique physicochemical properties due to their small size. Nanozymes, in particular, have been widely used in biosensing, disease treatment, pollutant degradation, and antibacterial therapy due to their inherent stability and low toxicity. Nanozymes can generate reactive oxygen species, including hydroxyl radicals, hydrogen peroxide, and singlet oxygen, through single-electron reduction reactions. Among various enzyme activities, peroxidase activity is the most prominent because it can convert low concentrations of H₂O₂ into hydroxyl radicals, thereby disrupting biofilms and killing bacteria. However, reports on inorganic nanomaterials that act as both photosensitizers (PTA) and nanozyme activities are very limited.

[0005] Among them, molybdenum disulfide nanomaterials possess peroxidase-like activity and photothermal therapy capabilities, enabling rapid and efficient bacterial clearance in vitro and wound disinfection in vivo. Although PTT has made considerable progress in the application of near-infrared light in region I, its poor penetration ability and depth still limit the clinical application of these therapies to some extent. In summary, a novel inorganic nanomaterial with nanozyme activity and photosensitive properties is a key research direction. Summary of the Invention

[0006] Based on the above, in order to eliminate highly resistant MRSA, this invention proposes a monolayer W@MoS2 nanosheet, its preparation method, and its application.

[0007] The purpose of this invention is:

[0008] I. Overcoming the problems of poor tissue penetration and low ROS catalytic activity of materials in photothermal therapy;

[0009] Second, it can effectively enhance the light and heat absorption capacity of materials and avoid damage to cell tissues during PTT antibacterial treatment;

[0010] Third, it can enhance the bactericidal effect of materials.

[0011] To achieve the above objectives, the present invention adopts the following technical solution.

[0012] A method for preparing monolayer W@MoS2 nanosheets

[0013] The method includes:

[0014] 1) Dissolve water-soluble molybdate and water-soluble tungstate in water and mix thoroughly to obtain a mixed solution;

[0015] 2) Add sulfur source and organic solvent to the mixture, mix and react, then dry to obtain powder.

[0016] As a preferred option

[0017] Step 1) The water-soluble molybdate is an alkali metal molybdate and / or an alkali metal permolybdate;

[0018] Step 1) The water-soluble tungstate is an alkali metal tungstate and / or an alkali metal pertungstate, and its dosage is 0.3-0.4 g / g water-soluble molybdate;

[0019] In step 1), when dissolving the water-soluble molybdate and water-soluble tungstate, the amount of water used is 2-5 mL / g of water-soluble molybdate.

[0020] As a preferred option

[0021] The sulfur source in step 2) is thiourea, and its dosage is 0.30-0.35 g / g water-soluble molybdate;

[0022] The organic solvent in step 2) is oxalic acid, and the amount used is 5-5.5 mL / g of water-soluble molybdate.

[0023] As a preferred option

[0024] The reaction described in step 2) is carried out at a constant temperature of 180–220°C for 22–26 hours.

[0025] A monolayer W@MoS2 nanosheet.

[0026] An application of a monolayer W@MoS2 nanosheet,

[0027] The monolayer W@MoS2 nanosheets are used to participate in biochemical catalytic reactions and / or antibacterial and / or promote wound repair.

[0028] As a preferred option

[0029] The monolayer W@MoS2 nanosheets are used for in vitro antibacterial and / or wound thermal repair and / or biofilm disruption and sterilization. In this invention, a transition metal dihalide is prepared using Na2MoO4·2H2O, thiourea, and C2H2O4·2H2O as raw materials. MoS2 has a unique electronic configuration and structure, with strong covalent or ionic bonds within the layers, but loosely bonded by weak van der Waals forces between layers. This invention uses a simple and efficient hydrothermal combined method, which is environmentally friendly and easy to operate. The specific morphology and unique size of the antibacterial material ensure that it exerts a good antibacterial effect at a low concentration. It can not only deposit on the bacterial surface to cause membrane permeability and directly disrupt the cell wall, but also enter the cell to exert a good antibacterial effect by mediating reactive oxygen species. To ensure its well-defined monolayer structure and nanoscale size, this invention controls the morphology of the product by changing the raw material ratio and setting different reaction conditions.

[0030] MoS2 exhibits uniform composition, continuous growth, and low impurity levels. Its unique layered structure enhances mass transfer and ion diffusion. As the amount of molybdenum salt decreases, the thin interlayer structure tends to exfoliate into fewer or even monolayers. However, using only a small amount of molybdenum salt results in dispersed and irregularly shaped single-crystal particles, rather than continuous nanosheets. More importantly, MoS2 allows for the easy intercalation of certain molecules, atoms, or ions. When thiourea is converted to ammonium thiocyanate at high temperatures and intercalated in situ into MoS2, the interlayer spacing widens, further optimizing the electronic structure. In-situ intercalation inhibits MoS2 growth, reduces material size, exposes more active sites, and increases the exposed active edges. Excessive thiourea disrupts the monolayer structure, and excessive ammonium ion intercalation widens the MoS2 interlayer spacing. Active oxygen clusters promote nucleation, while thiourea inhibits their growth, causing the material to tend towards a flower-like or spherical shape. Testing revealed that not only did the crystals fail to grow according to their preferred orientation, leading to severe structural distortion and disjunction, but unsaturated sulfides also formed.

[0031] To ensure high yield, purity, and crystallinity of the obtained nanosheets, this invention specifies the reaction conditions. According to research by those skilled in the art, under suitable temperature conditions, MoS2 can retain the 1T phase with more active sites, resulting in a regular material morphology and clear layered structure. Too low a reaction temperature leads to product agglomeration, excessively large product particle size, weak interlayer bonding of the layered nanosheets, and structural damage, which can affect the material's application in antibacterial processes. Too high a temperature leads to the appearance of MoO2 and MoO3 in the product, significantly reducing the effective conversion rate and weakening the antibacterial activity.

[0032] MoS2 nanosheets exhibit high catalytic activity, with their active sites located at the material edges. However, their basal surface activity is poor, and using them alone leads to unstable reactive oxygen clusters that are consumed too quickly, affecting the material's antibacterial effect. To fully utilize the advantages of monolayer two-dimensional materials, this invention employs Na2WO4·2H2O atomic doping modification to stimulate active sites on the basal surface of MoS2 nanosheets, thereby enhancing their catalytic performance. Alkali metal tungsten atoms are small in size and highly reactive, allowing for effective doping into the interlayer and forming intercalation compounds. The substitution of alkali metal tungsten atoms alters the material's structure, generating new phases, providing more active centers, improving the catalytic activity of MoS2, enhancing electron transfer capabilities, and promoting the formation of 1T-type MoS2. Tungsten atoms accelerate the reversible transformation of polysulfides, preventing sulfur passivation and improving the catalytic activity of W@MoS2. Simultaneously, tungsten atom doping provides the material with more microporous structures, increasing the specific surface area and achieving a better confinement effect.

[0033] The exogenous active sites and graphene-like layered structure endow monolayer W@MoS2 nanosheets with peroxidase-like activity, enabling them to locally catalyze low concentrations of hydrogen peroxide and generate hydroxyl radicals. They exhibit high photothermal conversion efficiency and photothermal stability under near-infrared light irradiation. Through their peroxidase-like active sites, they accelerate intrabacterial oxidation reactions, consuming antioxidant biomolecules and leading to the accumulation of highly antibacterial reactive oxygen species.

[0034] Monolayer W@MoS2 nanosheets possess antibacterial drug carrier properties and photodynamic antibacterial activity, making them suitable for preparing inhibitors of drug-resistant bacteria, inhibitors of drug-resistant bacterial biofilms, and therapeutic agents for subcutaneous drug-resistant bacterial abscesses. The material activates oxygen atoms through sensitization with specific wavelengths of light, resulting in an O→Mo charge transition. The activated high-energy oxygen state exerts a bactericidal effect. Testing revealed that the photothermal performance and efficiency of the W@MoS2 prepared in this invention are significantly improved. This significant improvement in photothermal performance enhances the effectiveness of chemical kinetics, overcoming the shortcomings of insufficient chemodynamic therapy and producing a stronger synergistic antibacterial effect. Photothermal therapy using W@MoS2 can effectively prevent bacterial resistance and reduce damage to cells and tissues, providing a feasible strategy for the effective treatment of wounds infected with methicillin-resistant Staphylococcus aureus (MRSA), and also providing a reliable direction for the design and application of two-dimensional nanomaterial Mxene catalysts.

[0035] The beneficial effects of this invention are as follows:

[0036] (1) The monolayer W@MoS2 nanosheet material based on the two-dimensional nanomaterial Mxene has peroxidase-like catalytic activity, which can effectively overcome the problems of poor tissue penetration of photothermal therapy and low ROS catalytic activity of the material.

[0037] (2) Monolayer W@MoS2 nanosheets have a unique two-dimensional planar structure with a large specific surface area, exhibiting good optical and electronic properties. They have high photothermal absorption in the near-infrared II region, which means that the photothermal conversion efficiency is improved. At the same time, the peroxidase-like activity of monolayer W@MoS2 nanosheets enables efficient photothermal amplification, which can be used to treat methicillin-resistant Staphylococcus aureus infection and avoids thermal damage to normal tissues.

[0038] (3) Monolayer W@MoS2 nanosheets can achieve both mild antibacterial properties and good antibacterial effect. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the synthesis mode of monolayer W@MoS2 nanosheets.

[0040] Figure 2 The image shows the characterization of the monolayer W@MoS2 nanosheets in Example 1.

[0041] Figure 3 The image shows the photothermal and nanoenzyme performance test results of the monolayer W@MoS2 nanosheets in Example 1.

[0042] Figure 4 This is a graph showing the antibacterial properties of the monolayer W@MoS2 nanosheets in Example 1.

[0043] Figure 5 This is a tissue wound characterization diagram of a single-layer W@MoS2 nanosheet in Example 1.

[0044] The present invention will be further described clearly and in detail below with reference to specific embodiments and the accompanying drawings. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0045] Unless otherwise specified, all raw materials used in the embodiments of the present invention are commercially available or obtainable by those skilled in the art; unless otherwise specified, all methods used in the embodiments of the present invention are methods mastered by those skilled in the art.

[0046] Example 1

[0047] A method for preparing monolayer W@MoS2 nanosheets, the method comprising:

[0048] 1) Dissolve 10g Na2MoO4·2H2O and 3g Na2WO4·2H2O in 30mL of water and mix well to obtain a mixed solution;

[0049] 2) Add 3g of thiourea and 15mL of C2H2O4·2H2O to the mixture, mix, and keep at a constant temperature of 180℃ for 26h, then dry to obtain powder.

[0050] The characterization of the monolayer W@MoS2 nanosheets of this invention is as follows.

[0051] 1. TEM analysis and EDS analysis:

[0052] The morphology of the material in this example was analyzed using a dual-beam electron microscope (DB500).

[0053] 2. UV-vis-NIR analysis:

[0054] The photothermal properties of the material in this example were tested using a Cary 5000UV-Vis-NIR spectrophotometer.

[0055] 3. Biocatalytic performance analysis:

[0056] 3,3′,5,5′-tetramethylbenzidine (TMB) and o-phenylenediamine (OPD) were used as probes to monitor hydroxyl radicals and analyze catalytic performance in the presence of hydrogen peroxide, respectively.

[0057] The characterization results are as follows.

[0058] like Figure 2 As shown, W@MoS2 has a monolayer structure composed of a large number of nano-metals and exhibits some wrinkling, possessing the common characteristics of monolayer nanosheets. W@MoS2 exhibits polycrystalline properties, with corresponding planes displaying distinct diffraction rings. Mo, S, and W elements coexist. C, Mo, W, S, and O are present in the sample. The characteristic binding energies of Mo 3d3 / 2 and Mo 3d5 / 2 are 232.5 eV and 229.4 eV, respectively, confirming the presence of Mo. 4+ The existence of W·4f 7 / 2 and W·4f 5 / 2 The binding energies were 31.75 eV and 33.95 eV, respectively, and the appearance of the W·5P5 / 2 peak verified that W 4+ The presence of [a specific component / electrode] was also observed. Furthermore, the S 2p phase of divalent sulfur ions was found at 162.25 eV. 1 / 2 and S2p 3 / 2 These characterization results demonstrate that the present invention has successfully prepared monolayer W@MoS2 nanosheets.

[0059] like Figure 3 As shown, W@MoS2 has a wide absorption range for NIR-II laser energy, which is directly proportional to the increase of W@MoS2 concentration. Different concentrations (0, 50, 100 μg / mL) of W@MoS2 were used, and the laser energy was increased by 1064 nm and 1.0 W·cm⁻¹. -2 After 6 minutes of irradiation, the temperature of W@MoS2 was found to increase significantly with increasing concentration, irradiation time, and laser power density, reaching a maximum at 1.0 W·cm⁻¹. -2 Under these conditions, the temperature of 100 μg / mL W@MoS2 rose to 49 °C. This indicates that W@MoS2 exhibits good photothermal properties under NIR-II light irradiation.

[0060] To further evaluate the photothermal efficiency, the W@MoS2 suspension was tested in the near-infrared II region (1064 nm, 1.0 W·cm⁻¹). -2 Five heating / cooling cycles were performed at 6 min (6 hours), and the photothermal performance remained stable throughout the cycles. The heating / cooling curves showed a photothermal conversion efficiency (η) of 36.9%. These results indicate that W@MoS2 exhibits high photothermal conversion efficiency under NIR-II conditions.

[0061] The absorbance of TMB at 652 nm increased with increasing W@MoS2 concentration and near-infrared II exposure (1064 nm, 1.0 W·cm⁻¹). -2 The efficiency increased from 0 to 10 min. This indicates the inherent biocatalytic activity of W@MoS2, with a significant increase in catalytic efficiency due to improved reaction kinetics.

[0062] The catalytic activity of the catalyst was further evaluated using OPD. A phenomenon similar to TMB was observed using the OPD probe, confirming and demonstrating the intrinsic biocatalytic activity of W@MoS2. To further verify that NIR-II can enhance biocatalysis, the activity of W@MoS2 and the OPD absorbance at 420 nm were compared in the presence and absence of NIR-II. This indicates that ROS yield is significantly increased in the presence of NIR-II. Compared to MoS2, W@MoS2 exhibits better biocatalytic activity and photothermal effect.

[0063] The performance of the material in this example was tested using the following methods.

[0064] I) In vitro bactericidal properties:

[0065] Ia) Prepare a solution of 100 μL of methicillin-resistant Staphylococcus aureus to a concentration of 10. 6 A bacterial suspension of CFU / mL was dropped into a well plate, and a 0.1 mmol / L hydrogen peroxide solution was prepared. 0.1 mL of hydrogen peroxide was added per milliliter of bacterial suspension, the bacterial concentration was measured, and the sterilization rate of the material was calculated.

[0066] Ib) Prepare a solution of 100 μL of methicillin-resistant Staphylococcus aureus to a concentration of 10. 6 CFU / mL bacterial suspension was added dropwise to the well plate. A 100 μg / mL W@MoS2 aqueous solution was prepared using W@MoS2 and water. 0.1 mL of W@MoS2 aqueous solution was added per milliliter of bacterial suspension. The solution was then analyzed at a wavelength of 1064 nm and an intensity of 1 W·cm⁻¹. -2 The material was irradiated with laser for 6 minutes and cultured at 37-38℃ for 12 hours. The bacterial concentration was measured, and the sterilization rate of the material was calculated.

[0067] Ic) Mix the above 0.1 mmol / L hydrogen peroxide and 100 μg / mL W@MoS2 aqueous solution, repeat the test, detect the bacterial concentration, and calculate the sterilization rate of the material.

[0068] Id) Mix the above 0.1 mmol / L hydrogen peroxide and 100 μg / mL W@MoS2 aqueous solution, and repeat the test at a wavelength of 1064 nm and an intensity of 1 W·cm. -2 The material was irradiated with laser for 6 minutes and cultured at 37-38℃ for 12 hours. The bacterial concentration was measured, and the sterilization rate of the material was calculated.

[0069] The results are as follows.

[0070] Sterilization rate (Ia) Sterilization rate (Ib) Sterilization rate (Ic) Sterilization rate (Id) 31.4％ 34.7％ 39.6％ 44.1％

[0071] Prior to testing, the inhibitory effect of different concentrations of hydrogen peroxide (0.0025, 0.05, 0.1, 0.2, 0.4, and 0.8 μg / mL) on methicillin-resistant Staphylococcus aureus (MRSA) was investigated. The results showed that 0.1 mmol / L of hydrogen peroxide was sufficient to produce good antibacterial activity. Similarly, the results for W@MoS2 aqueous solution showed that 100 μg / mL of W@MoS2 aqueous solution was sufficient to produce good antibacterial activity. Furthermore, hydrogen peroxide can easily affect wound healing efficiency; therefore, its conversion to ·OH is necessary.

[0072] Based on the results in the table above, it can be analyzed that W@MoS2 has significant photothermal activity and indeed possesses nanozyme properties, capable of decomposing H2O2 into ·OH, thus proving its bactericidal ability. Simultaneously, the colony count in group Id) was significantly reduced, indicating that the photothermal effect can promote nanozyme activity, thereby producing higher bactericidal activity.

[0073] II) Wound thermal damage repair test:

[0074] A mouse dorsal cell abscess model was established and divided into 5 groups (I: PBS buffer, II: 100 μg / mL MoS2 + 0.1 mmol / L H2O2 aqueous solution, with a coordination strength of 1 W·cm). -2 NIR-II is denoted as MoS2+H2O2+NIR-II; III is denoted as W@MoS2+0.1mmol / L H2O2 aqueous solution; IV is denoted as W@MoS2+H2O2 aqueous solution; the auxiliary coordination strength is 1W·cm. -2 The NIR-II, denoted as W@MoS2+NIR-II, has a complexing strength of 100 μg / mL W@MoS2+0.1 mmol / L H2O2 aqueous solution and a complexing strength of 1 W·cm. -2 The NIR-II of PBS (denoted as W@MoS2+H2O2+NIR-II) was obtained, and the local temperature changes of PBS and W@MoS2 under 1064nm near-infrared irradiation were recorded by a thermal imager.

[0075] The results are as follows.

[0076] In a wound thermal injury repair test, rat body weight changes were recorded for 7 days, with no significant abnormalities observed. After 6 minutes of irradiation, the wound temperature rapidly increased from 28℃ to 49.8℃, while the temperature change in the PBS group was not significant, indicating that W@MoS2 possesses excellent photothermal properties. Figure 5 As shown in the representative wound photographs on days 0, 1, 3, 5, and 7, all mice developed wound infections during treatment. However, compared to the PBS group, the MoS2+H2O2 group did not accelerate wound healing, and wound symptoms remained evident on day 7. The PBS group still exhibited significant abscesses and slow wound healing, while the W@MoS2+H2O2+NIR-II treatment group showed the fastest wound healing and minimal edema. These results indicate that the temperature increase caused by 1064nm laser irradiation is unlikely to burn normal cell tissue, and that 50℃ is close to the optimal temperature for enzymatic reactions.

[0077] Wound healing occurred on day 5 in both the W@MoS2+H2O2 and W@MoS2+NIR-II groups, with varying degrees of enhancement on day 7. The relative wound area in the W@MoS2+H2O2+NIR-II group was significantly smaller than that in the PBS group, indicating that the W@MoS2+H2O2+NIR-II group promoted abscess healing. After 7 days of treatment, the colony plots and quantitative colony count analysis of the W@MoS2+H2O2+NIR-II group showed the lowest bacterial count compared to other groups, indicating...

[0078] The W@MoS2+H2O2+NIR-II group accelerated wound healing through effective antibacterial activity. In conclusion, the W@MoS2+H2O2+NIR-II method, with the synergistic effect of PTT and peroxidase, can be effectively used to treat wound lesions infected by drug-resistant bacteria.

[0079] III) Anti-biofilm test:

[0080] Based on test I), six sets of comparative experiments were conducted: I: PBS buffer, II: 0.1 mmol / L H2O2 aqueous solution, denoted as H2O2, III: 100 μg / mL MoS2 aqueous solution, denoted as MoS2, IV: 100 μg / mL MoS2 + 0.1 mmol / L H2O2 aqueous solution, denoted as MoS2 + H2O2, V: 100 μg / mL W@MoS2 aqueous solution, denoted as W@MoS2, VI: 100 μg / mL W@MoS2 + 0.1 mmol / L H2O2 aqueous solution, denoted as W@MoS2 + H2O2. Crystal violet was used to stain the residual biofilm, and the absorbance was measured at 590 nm to quantify the biofilm viability.

[0081] The results are as follows.

[0082] Since both PTT and nanozymes can disrupt biofilms and kill bacteria, this invention further evaluates the antibacterial ability of W@MoS2 through an anti-biofilm test. The results showed that the W@MoS2+H2O2+NIR-II group exhibited the strongest biofilm disruption effect, reducing biofilm survival rate to below 30%. Quantitative fluorescence intensity analysis using CLSM revealed that the W@MoS2+H2O2+NIR-II group showed strong red fluorescence, indicating that W@MoS2+H2O2+NIR-II effectively removed methicillin-resistant Staphylococcus aureus (MRSA). Furthermore, PBS-treated MRSA exhibited a round morphology and a smooth surface, while the MoS2+H2O2 group showed slight wrinkles but no damage. All groups containing W@MoS2 showed varying degrees of damage to the MRSA, including cell wall damage and cytoplasmic leakage. The W@MoS2+NIR-II+H2O2 group showed the most severe cell wall damage and cytoplasmic leakage. In summary, due to its nanozyme and photothermal properties, W@MoS2 has strong antibacterial potential, and the W@MoS2+H2O2+NIR-II group exhibits good anti-biofilm activity against methicillin-resistant Staphylococcus aureus.

[0083] Example 2

[0084] A method for preparing monolayer W@MoS2 nanosheets, the method comprising:

[0085] 1) Dissolve 10g Na2MoO4·2H2O and 3g Na2WO4·2H2O in 30mL of water and mix well to obtain a mixed solution;

[0086] 2) Add 3g of thiourea and 15mL of C2H2O4·2H2O to the mixture, mix, and keep at a constant temperature of 200℃ for 24h, then dry to obtain powder.

[0087] The same tests were performed on the materials in this example as in Example 1, and the results are as follows.

[0088]

[0089] This invention prepares monolayer W@MoS2 nanosheets using a simple and efficient hydrothermal combined method, resulting in high yield, purity, and crystallinity. Characterization revealed that the monolayer W@MoS2 nanosheets retain a 1T phase with more active sites, exhibiting a regular morphology and clear layered structure. Deposition on bacterial surfaces induces membrane permeability, enhancing penetration into tissue cells and improving bactericidal efficacy. Experimental results showed that within the optimal temperature range for the enzymatic reaction, W@MoS2 significantly improved the clearance of bacteria from wounds, with mouse wounds beginning to heal within 4–5 days, indicating that W@MoS2 demonstrates high activity in stimulating tissue cell proliferation and promoting wound healing.

[0090] In the anti-biofilm test, the group containing W@MoS2 showed a stronger effect on biofilm disruption, with biofilm survival rates dropping below 30%. Furthermore, methicillin-resistant Staphylococcus aureus (MRSA) exhibited significant cell wall damage and cytoplasmic leakage. Compared to Example 1, the cell structure was severely damaged, and the cell wall completely lost its supporting function, indicating that W@MoS2 has significant anti-biofilm activity against MRSA.

[0091] Based on the above experimental results, it can be concluded that the photothermal performance and efficiency of monolayer W@MoS2 nanosheets are significantly improved, thereby enhancing the effectiveness of chemical kinetics and producing a stronger synergistic antibacterial effect. Photothermal therapy using W@MoS2 can effectively prevent bacterial resistance and reduce damage to cells and tissues, providing a feasible strategy for the effective treatment of wounds infected with methicillin-resistant Staphylococcus aureus (MRSA).

[0092] Example 3

[0093] A method for preparing monolayer W@MoS2 nanosheets, the method comprising:

[0094] 1) Dissolve 10g Na2MoO4·2H2O and 3g Na2WO4·2H2O in 30mL of water and mix well to obtain a mixed solution;

[0095] 2) Add 3g of thiourea and 15mL of C2H2O4·2H2O to the mixture, mix, and keep at a constant temperature of 220℃ for 22h, then dry to obtain powder.

[0096] The same tests were performed on the materials in this example as in Example 1, and the results are as follows.

[0097]

[0098] Based on the results in the table above, it can be seen that the bactericidal effect of W@MoS2 nanosheets against methicillin-resistant Staphylococcus aureus (MRSA) is reduced. In the anti-biofilm test, the biofilm survival rate is approximately 30%, and the degree of bacterial damage is not as severe as in Example 2. This is because the higher temperature leads to the formation of MoO2 and MoO3 in the product, which reduces the effective conversion rate of the MoS2 structure, thereby weakening the antibacterial activity.

[0099] Example 4

[0100] A method for preparing monolayer W@MoS2 nanosheets, the method comprising:

[0101] 1) Dissolve 10g Na2MoO4·2H2O and 4g Na2WO4·2H2O in 30mL of water and mix well to obtain a mixed solution;

[0102] 2) Add 3g of thiourea and 15mL of C2H2O4·2H2O to the mixture, mix, and keep at a constant temperature of 200℃ for 24h, then dry to obtain powder.

[0103] The same tests were performed on the materials in this example as in Example 1, and the results are as follows.

[0104]

[0105] Based on the results in the table above, this example increased the amount of tungsten salt, while the amount of molybdenum salt decreased. According to research by those skilled in the art, the interlayer weakness of MoS2 causes the material to tend to peel into fewer or single layers, further resulting in dispersed and irregularly shaped single-crystal particles. In other words, the composition of the W@MoS2 nanosheets in this example is uneven, and compared to Example 2, its mass transfer and ion diffusion capabilities are poor, and its various properties are significantly reduced.

[0106] Comparative Example 1

[0107] A method for preparing monolayer W@MoS2 nanosheets, the method comprising:

[0108] 1) Dissolve 10g Na2MoO4·2H2O and 3g Na2WO4·2H2O in 30mL of water and mix well to obtain a mixed solution;

[0109] 2) Add 3g of thiourea and 15mL of C2H2O4·2H2O to the mixture, mix, and keep at a constant temperature of 160℃ for 30h, then dry to obtain powder.

[0110] The same tests were performed on the materials in this example as in Example 1, and the results are as follows.

[0111]

[0112] Based on the results in the table above, it can be seen that the bactericidal performance of W@MoS2 nanosheets is reduced, and the amount of cytoplasmic efflux is also less. This is because the lower reaction temperature leads to product aggregation, resulting in excessively large product particle sizes and weaker interlayer bonding in the layered nanosheets. This makes the structure of the material in this example prone to failure, thus affecting its application in the antibacterial process. Larger W@MoS2 particles exhibit greater stability, indicating fewer exposed active sites.

[0113] Comparative Example 2

[0114] A method for preparing monolayer MoS2 nanosheets, the method comprising:

[0115] 1) Dissolve 10g of Na2MoO4·2H2O in 30mL of water and mix well to obtain a mixed solution;

[0116] 2) Add 3g of thiourea and 15mL of C2H2O4·2H2O to the mixture, mix, and keep at a constant temperature of 200℃ for 24h, then dry to obtain powder.

[0117] The same tests were performed on the materials in this example as in Example 1, and the results are as follows.

[0118]

[0119] According to the results in the table, the MoS2 nanosheets have few active sites on their substrate. In this case, no atomic doping modification was performed, resulting in fewer active centers and poor catalytic performance. The stable 2H form of MoS2 slows down electron transfer, and sulfur readily passivates, improving the material's catalytic stability. MoS2 exhibits insufficient photothermal activity; in wound thermal damage repair tests, the MoS2+H2O2 and MoS2+H2O2+NIR-II groups showed significantly slower wound healing and more pronounced abscesses. Lasers easily burn normal cell tissue. Furthermore, the material in this case exhibits poor anti-biofilm activity, with a significantly lower degree of cell damage compared to W@MoS2 nanosheets.

[0120] Comparative Example 3

[0121] A method for preparing W@graphene, the method comprising:

[0122] 1) Disperse 10g of graphene and 3g of WCl6 in 30mL of ethanol and mix well to obtain a mixed solution;

[0123] 2) Add 3g of thiourea and 15mL of C2H2O4·2H2O to the mixture, mix, and keep at a constant temperature of 200℃ for 24h, then dry to obtain powder.

[0124] The same tests were performed on the materials in this example as in Example 1, and the results are as follows.

[0125]

[0126] The material obtained in this example is W@graphene. Although its structure is similar to that of W@MoS2 nanosheets, and it also possesses abundant exogenous active sites and a peroxidase-like structure, the surface of graphene is rich in negatively charged oxygen-containing functional groups, while W... 6+ The oxygen-containing functional groups adsorb onto the graphene surface via electrostatic interactions. After alcoholysis, WO3 is generated in situ through dehydration at high temperature. However, hydrogen bonds exist between -OH and H2O and WO3, leading to incomplete dehydration and the formation of trace amounts of WO3·xH2O impurities. The presence of COW bonds between WO3 and graphene results in numerous defects, severe edge curling of the nanosheets, and the formation of many flower-like aggregates. This leads to heterogeneous composition and poor antibacterial and anti-biofilm activity in the material.

[0127] Comparative Example 4

[0128] A method for preparing monolayer W@MoS2 nanosheets, the method comprising:

[0129] 1) Dissolve 10g Na2MoO4·2H2O and 3g Na2WO4·2H2O in 30mL of water and mix well to obtain a mixed solution;

[0130] 2) Add 4g of thiourea and 15mL of C2H2O4·2H2O to the mixture, mix, and keep at a constant temperature of 200℃ for 24h, then dry to obtain powder.

[0131] The same tests were performed on the materials in this example as in Example 1, and the results are as follows.

[0132]

[0133] In this example, excessive thiourea disrupts the monolayer structure of the material. Excessive ammonium ion intercalation increases the interlayer spacing of MoS2, while reactive oxygen species promote nucleation, which is inhibited by thiourea, causing the material to tend towards a flower-like or spherical shape. Testing revealed that not only did the crystals fail to grow according to their preferred orientation, resulting in severe structural distortion and disjointing, but unsaturated sulfides also formed. While MoS2 nanosheets exhibit high catalytic activity with active sites located at the material edges, their basal surface activity is poor. Furthermore, using them alone leads to instability and rapid consumption of reactive oxygen species, negatively impacting the material's antibacterial effect.

[0134] Comparative Example 5

[0135] Commercially available Ag@MoS2 materials.

[0136] The performance of the material in Example 2 and this example was tested using the following methods.

[0137] Long-lasting antibacterial test:

[0138] Prepare a 100 μL solution of methicillin-resistant Staphylococcus aureus (MRSA) to achieve a concentration of 10. 6 CFU / mL bacterial suspension was added to wells of a plate. Materials were then prepared using PBS buffer (pH=7) to a concentration of 100 μg / mL, and divided into two groups, A and B. Group A used the W@MoS2 material from Example 2, and Group B used the Ag@MoS2 material selected in this example. The solutions were allowed to stand for 5 days. The supernatant was collected daily, and 0.1 mL of the solution was added to each well of the plate per milliliter of bacterial suspension. The survival rate of methicillin-resistant Staphylococcus aureus (MRSA) was detected and calculated.

[0139] The results are as follows.

[0140] Group A Day 1 Day 2 Day 3 Day 4 Day 5 Survival rate 0.4％ 1.0％ 4.6％ 5.7％ 8.9％ Group B Day 1 Day 2 Day 3 Day 4 Day 5 Survival rate 0.7％ 1.5％ 7.9％ 14.5％ 22.4％

[0141] Based on the results in the table above, commercially available Ag@MoS2 materials can release bactericidal ions, exhibiting good antibacterial effects in a short period. Furthermore, the materials possess a large specific surface area and good biocompatibility, promoting oxidative stress and disrupting bacterial cell walls. In particular, the formation of Ag-S bonds can slow down the release of bactericidal Ag ions within a certain timeframe. + The release of ions. But Ag + The binding of ions to MoS2 is poor, the toxicity caused by instantaneous release is difficult to resolve, and it can also aggregate, thus affecting the bactericidal effect. Moreover, the cost of this material is obviously too high, and its prospects in the field of antibacterial materials are not as good as those of the material of this invention.

Claims

1. A method for preparing monolayer W@MoS2 nanosheets, characterized in that, The method includes: 1) Dissolve water-soluble molybdate and water-soluble tungstate in water and mix thoroughly to obtain a mixed solution; 2) Add a sulfur source and an organic solvent to the mixture, mix and react, then dry to obtain powder; Step 1) The water-soluble molybdate is an alkali metal molybdate and / or an alkali metal permolybdate; Step 1) The water-soluble tungstate is an alkali metal tungstate and / or an alkali metal pertungstate, and its dosage is 0.3-0.4 g / g water-soluble molybdate; Step 2) The sulfur source is thiourea, and its dosage is 0.30-0.35 g / g water-soluble molybdate; The reaction described in step 2) was carried out at a constant temperature of 180–220 °C for 22–26 h.

2. The method for preparing a single-layer W@MoS2 nanosheet according to claim 1, characterized in that, In step 1), when dissolving the water-soluble molybdate and water-soluble tungstate, the amount of water used is 2 to 5 mL / g of water-soluble molybdate.

3. The method for preparing a single-layer W@MoS2 nanosheet according to claim 1, characterized in that, The organic solvent in step 2) is oxalic acid, and the amount used is 5-5.5 mL / g of water-soluble molybdate.

4. A monolayer W@MoS2 nanosheet prepared by any one of claims 1 to 3.

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