A Cu-MoS2 nano-enzyme with adjustable catalytic ability and morphology, and a preparation method and application thereof

Abstract

This invention discloses a Cu-MoS2 nanozyme with tunable catalytic activity and morphology, its preparation method, and its applications. The invention employs a solvothermal method to prepare an atomically dispersed Cu-MoS2 nanozyme by coordinating (NH4)2MoS4 and Cu in a DMF solution. The tunable Cu content enables the product to exhibit tunable peroxidase-like, superoxide dismutase-like, and glutathione oxidase-like activities. Simultaneously, the introduction of Cu enriches the catalytic sites on the substrate, shifting the entire catalytic process to Cu sites and enhancing the peroxidase-like activity of Cu-MoS2. Furthermore, this nanozyme exhibits excellent antibacterial properties; at a H2O2 concentration of 1 mM and a sample concentration of 50 μg / mL, it achieves an antibacterial rate of 99% against Staphylococcus aureus, potentially providing an effective solution to the persistent challenge of bacterial infections.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials technology and relates to novel nano-mimetic enzymes, specifically to a Cu-MoS2 nanozyme with tunable catalytic ability and morphology, its preparation method, and its application. Background Technology

[0002] In recent years, with the rapid development of nanotechnology, nanozymes have increasingly come into focus. Due to their diverse enzyme-like properties, tunable enzyme-like characteristics, and physicochemical stability, they can be used in various fields such as biosensors, cancer treatment, antibacterial applications, and chemical synthesis, showing great promise for development. MoS2, as a two-dimensional transition metal dichalcogenide, has attracted considerable attention in this field. Its low band gap allows it to fully utilize the solar spectrum from UV to Vis to generate photogenerated electron-hole pairs, and it can also utilize infrared light to generate heat.

[0003] As a nanozyme, MoS2 has been shown to possess a variety of enzyme-mimicking catalytic properties, such as catalase-like, peroxidase-like, superoxide dismutase-like, and glutathione oxidase-like activities. However, a major limitation of MoS2 is that its catalytic activity is mainly concentrated at the edges, and the (002) basal plane of MoS2 is almost catalytically inert, which limits the application of MoS2. Overcoming these limitations has been a focus of recent innovations.

[0004] Patent document CN115779965A introduces polydopamine as a linking bridge between MoS2 and Cu nanoparticles in the preparation method of MoS2-based nanozymes, so that small-sized Cu nanoparticles can be uniformly dispersed on the surface of MoS2. The preparation method of combining MoS2 nanosheets with Cu nanoparticles is relatively complex and has problems such as difficulty in effectively doping metal into the crystal lattice during the doping process and inability to accurately control the proportion of introduced elements. Summary of the Invention

[0005] The purpose of this invention is to provide a Cu-MoS2 nanozyme with tunable catalytic ability and morphology that can solve the problems of difficulty in effectively doping metal into the crystal lattice and the inability to precisely control the proportion of introduced elements in the existing technology. The preparation method and application of the nanozyme are also described.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows: A DMF solution of CuCl2 is added to a DMF solution of (NH4)2MoS4 at a copper-molybdenum molar ratio of 0.1 to 0.9:1, followed by ultrasonication and stirring to obtain a homogeneous mixed solution. The mixed solution is then subjected to a solvothermal reaction in a high-pressure reactor at 180-220°C for 18-24 hours. The product is then separated by centrifugation and washed to obtain Cu-MoS2 nanozymes with controllable catalytic activity and morphology.

[0007] The (NH4)2MoS4 DMF solution is prepared by adding (NH4)2MoS4 to DMF, sonicating for 10 min, and stirring for 30 min to obtain a (NH4)2MoS4 DMF solution with a concentration of 3-4 mg / mL.

[0008] The CuCl2 DMF solution is obtained by adding CuCl2 to a sufficient amount of DMF solution that can completely dissolve CuCl2 and then ultrasonically stirring.

[0009] The autoclave is a stainless steel autoclave lined with polytetrafluoroethylene.

[0010] The reaction filling rate of the solvothermal reaction is 50-60%.

[0011] The centrifugation process involves separating the product by centrifuging at 10,000 rpm for 5 minutes, followed by washing three times with deionized water and ethanol.

[0012] The Cu-MoS2 nanozyme prepared by the above method has catalytic activity and morphology that can be controlled. The Cu atoms of the Cu-MoS2 nanozyme are uniformly distributed at the atomic level on the MoS2 group, and the activity of the nanozyme can be controlled by adjusting the copper content.

[0013] When the copper-molybdenum molar ratio is 0.1~0.5:1, Cu-MoS2 nanozymes exhibit a nanorod structure formed by self-assembled nanoflowers. When the copper-molybdenum molar ratio is 0.7~0.9:1, Cu-MoS2 nanozymes exhibit a hollow nanobox structure assembled from nanoflowers.

[0014] When the copper-molybdenum molar ratio is 0.3:1, the prepared Cu-MoS2 nanozyme exhibits peroxidase-like activity; when the copper-molybdenum molar ratio is 0.7:1, the prepared Cu-MoS2 nanozyme exhibits superoxide dismutase-like activity; and when the copper-molybdenum molar ratio is 0.9:1, the prepared Cu-MoS2 nanozyme exhibits glutathione oxidase-like activity.

[0015] The Cu-MoS2 nanozyme of the present invention, with tunable catalytic ability and morphology, has antibacterial properties. The antibacterial effect is obvious when the copper-molybdenum molar ratio is 0.2~0.4:1, and the addition of H2O2 can improve the antibacterial effect.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. Effectiveness of element introduction: This invention successfully achieved uniform dispersion of Cu in the MoS2 structure with adjustable Cu doping content. ICP analysis confirmed that the Cu content in the sample matched the molar ratio used during preparation, demonstrating the precise introduction of Cu.

[0018] 2. Enhanced Catalytic Performance: At a copper-molybdenum molar ratio of 0.3:1, Cu-MoS2 nanozymes exhibited significantly enhanced catalytic activity, with its V... max and k cat The value is higher than that of pure MoS2 and other proportions of Cu-MoS2 nanozymes. This indicates that the optimized Cu content can maximize the catalytic efficiency of the nanozyme.

[0019] 3. Significant antibacterial effect: Under the condition of adding H2O2, Cu-MoS2 nanozymes (such as a copper-molybdenum molar ratio of 0.3:1) exhibit an antibacterial rate of over 99% against Staphylococcus aureus, demonstrating excellent antibacterial performance. This effect is mainly attributed to the POD activity of the nanozyme, which can effectively convert H2O2 into highly oxidizing •OH free radicals.

[0020] 4. Multifunctionality and practicality: The Cu-MoS2 nanozyme of the present invention not only has POD activity, but also exhibits SOD-like activity and GSH-OXD-like activity, which makes it possible for its wide application in the fields of biomedicine, environmental protection and energy conversion.

[0021] 5. Controllability and Stability: By adjusting the molar ratio of Cu to Mo, the morphology and properties of Cu-MoS2 nanozymes can be precisely controlled to meet the needs of different application scenarios. Simultaneously, the prepared nanozymes exhibit good stability, ensuring their reliability and durability in practical applications.

[0022] In summary, this technical solution provides a method for preparing Cu-MoS2 nanozymes with high catalytic activity, significant antibacterial effect, multifunctionality, controllability, and stability, which has broad practical value and application prospects. Attached Figure Description

[0023] Figure 1 XRD patterns of MoS2 and Cx-M;

[0024] Figure 2 ICP spectra of MoS2 and Cx-M;

[0025] Figure 3 TEM images of MoS2 and Cx-M;

[0026] Figure 4 The EDS spectrum of C3-M prepared for Example 1;

[0027] Figure 5 HRTEM spectra of MoS2 and Cx-M;

[0028] Figure 6 Aberration-corrected scanning transmission microscopy (Ac-STEM) image of C3-M prepared in Example 1.

[0029] Figure 7 The change of absorbance of NBT treated with 20 μg / mL MoS2 and Cx-M over time at a wavelength of 680 nm;

[0030] Figure 8 The scavenging rates of superoxide anions by MoS2 and Cx-M;

[0031] Figure 9 Images of NBT processed with MoS2 and Cx-M at different times;

[0032] Figure 10 The scavenging rates of GSH by MoS2 and Cx-M;

[0033] Figure 11 Photographs showing the growth of Staphylococcus aureus treated with 100 μg / mL MoS2 and Cx-M in the absence of H2O2 and with the addition of H2O2; Detailed Implementation

[0034] The specific content of the present invention will be further explained in detail below with reference to the embodiments.

[0035] This invention employs a solvothermal method to prepare atomically dispersed Cu-MoS2 nanozymes by coordinating (NH4)2MoS4 and Cu in DMF solution. The adjustable Cu content enables Cu-MoS2 to exhibit tunable peroxidase-like, superoxide dismutase-like, and glutathione oxidase-like activities. The introduction of Cu leads to strong bonding between Cu and S, and electron cloud overlap between Cu and Mo, resulting in a significant shift of Cu electrons towards S and Mo. This causes substantial changes in the electronic structures of S and Mo, optimizing electronic regulation and endowing Cu-MoS2 with excellent superoxide dismutase-like activity. Simultaneously, the introduction of Cu enriches the catalytic sites on the substrate, shifting the entire catalytic process towards Cu sites and enhancing the peroxidase-like activity of Cu-MoS2.

[0036] The Cu-MoS2 nanozyme prepared by this invention achieves a uniform atomic distribution of Cu atoms on the MoS2 matrix, and the copper content is adjustable, thus allowing for precise control of the nanozyme activity. Specifically, with changes in Cu doping amount, the Cu-MoS2 nanozyme exhibits different structures and morphologies. Undoped MoS2 exhibits a sheet-like structure. When the copper-molybdenum molar ratio is 10-50%, the Cu-MoS2 nanozyme exhibits a nanorod structure formed by self-assembled nanoflowers. When a large amount of Cu is incorporated (copper-molybdenum molar ratio of 70-90%), the Cu-MoS2 nanozyme exhibits a hollow nanobox structure assembled from nanoflowers.

[0037] When the copper-molybdenum molar ratio is 30%, the prepared Cu-MoS2 nanozyme exhibits good peroxidase-like activity; when the copper-molybdenum molar ratio is 70%, the prepared Cu-MoS2 nanozyme exhibits good superoxide dismutase-like activity; and when the copper-molybdenum molar ratio is 90%, the prepared Cu-MoS2 nanozyme exhibits good glutathione oxidase-like activity. The Cu-MoS2 nanozyme prepared at a copper-molybdenum molar ratio of 30% shows the best antibacterial effect, achieving an antibacterial rate of 99% against Staphylococcus aureus at an H2O2 concentration of 1 mM and a sample concentration of 50 μg / mL.

[0038] Example 1

[0039] 1) Add (NH4)2MoS4 to DMF, sonicate for 10 min, stir for 30 min to obtain a DMF solution of (NH4)2MoS4 with a concentration of 3.125 mg / mL. Add CuCl2 to a sufficient amount of DMF solution that can completely dissolve CuCl2 and sonicate to obtain a DMF solution of CuCl2.

[0040] 2) Add CuCl2 DMF solution to (NH4)2MoS4 DMF solution at a copper-molybdenum molar ratio of 0.3:1, then sonicate and stir until homogeneous to obtain a mixed solution;

[0041] 3) The mixed solution was transferred to a polytetrafluoroethylene-lined stainless steel autoclave at a filling ratio of 60%. After solvothermal reaction in the autoclave at 200°C for 20 hours, the product was separated by centrifugation at 10,000 rpm for 5 minutes and washed three times with deionized water and ethanol to obtain Cu-MoS2 nanozymes with a Cu:Mo molar ratio of 0.3:1.

[0042] Example 2

[0043] 1) Add (NH4)2MoS4 to DMF, sonicate for 10 min, stir for 30 min to obtain a DMF solution of (NH4)2MoS4 with a concentration of 3.125 mg / mL. Add CuCl2 to a sufficient amount of DMF solution that can completely dissolve CuCl2 and sonicate to obtain a DMF solution of CuCl2.

[0044] 2) Add CuCl2 DMF solution to (NH4)2MoS4 DMF solution at a copper-molybdenum molar ratio of 0.5:1, then sonicate and stir until homogeneous to obtain a mixed solution;

[0045] 3) The mixed solution was transferred to a polytetrafluoroethylene-lined stainless steel autoclave at a filling ratio of 50%. After solvothermal reaction in the autoclave at 180°C for 22 hours, the product was separated by centrifugation at 10,000 rpm for 5 minutes and washed three times with deionized water and ethanol to obtain Cu-MoS2 nanozymes with a Cu:Mo molar ratio of 0.5:1.

[0046] Example 3

[0047] 1) Add (NH4)2MoS4 to DMF, sonicate for 10 min, stir for 30 min to obtain a DMF solution of (NH4)2MoS4 with a concentration of 3.125 mg / mL. Add CuCl2 to a sufficient amount of DMF solution that can completely dissolve CuCl2 and sonicate to obtain a DMF solution of CuCl2.

[0048] 2) Add CuCl2 DMF solution to (NH4)2MoS4 DMF solution at a copper-molybdenum molar ratio of 0.7:1, then sonicate and stir until homogeneous to obtain a mixed solution;

[0049] 3) The mixed solution was transferred to a polytetrafluoroethylene-lined stainless steel autoclave at a filling ratio of 55%. After solvothermal reaction in the autoclave at 200°C for 19 hours, the product was separated by centrifugation at 10,000 rpm for 5 minutes and washed three times with deionized water and ethanol to obtain Cu-MoS2 nanozymes with a Cu:Mo molar ratio of 0.7:1.

[0050] Example 4

[0051] 1) Add (NH4)2MoS4 to DMF, sonicate for 10 min, stir for 30 min to obtain a DMF solution of 4 mg / mL (NH4)2MoS4, add CuCl2 to a sufficient amount of DMF solution that can completely dissolve CuCl2 and sonicate to obtain a DMF solution of CuCl2.

[0052] 2) Add CuCl2 DMF solution to (NH4)2MoS4 DMF solution at a copper-molybdenum molar ratio of 0.1:1, then sonicate and stir until homogeneous to obtain a mixed solution;

[0053] 3) The mixed solution was transferred to a polytetrafluoroethylene-lined stainless steel autoclave at a filling ratio of 58%. After solvothermal reaction in the autoclave at 220°C for 18 hours, the product was separated by centrifugation at 10,000 rpm for 5 minutes and washed three times with deionized water and ethanol to obtain Cu-MoS2 nanozymes with a Cu:Mo molar ratio of 0.1:1.

[0054] Example 5

[0055] 1) Add (NH4)2MoS4 to DMF, sonicate for 10 min, stir for 30 min to obtain a DMF solution of (NH4)2MoS4 with a concentration of 3 mg / mL. Add CuCl2 to a sufficient amount of DMF solution that can completely dissolve CuCl2 and sonicate to obtain a DMF solution of CuCl2.

[0056] 2) Add CuCl2 DMF solution to (NH4)2MoS4 DMF solution at a copper-molybdenum molar ratio of 0.9:1, then sonicate and stir until homogeneous to obtain a mixed solution;

[0057] 3) The mixed solution was transferred to a polytetrafluoroethylene-lined stainless steel autoclave at a filling ratio of 52%. After solvothermal reaction in the autoclave at 190°C for 23 hours, the product was separated by centrifugation at 10,000 rpm for 5 minutes and washed three times with deionized water and ethanol to obtain Cu-MoS2 nanozymes with a Cu:Mo molar ratio of 0.9:1.

[0058] Example 6

[0059] 1) Add (NH4)2MoS4 to DMF, sonicate for 10 min, stir for 30 min to obtain a DMF solution of (NH4)2MoS4 with a concentration of 3.5 mg / mL. Add CuCl2 to a sufficient amount of DMF solution that can completely dissolve CuCl2 and sonicate to obtain a DMF solution of CuCl2.

[0060] 2) Add CuCl2 DMF solution to (NH4)2MoS4 DMF solution at a copper-molybdenum molar ratio of 0.4:1, then sonicate and stir until homogeneous to obtain a mixed solution;

[0061] 3) The mixed solution was transferred to a polytetrafluoroethylene-lined stainless steel autoclave at a filling ratio of 52%. After solvothermal reaction in the autoclave at 210°C for 19 hours, the product was separated by centrifugation at 10,000 rpm for 5 minutes and washed three times with deionized water and ethanol to obtain Cu-MoS2 nanozymes with a Cu:Mo molar ratio of 0.4:1.

[0062] Example 7

[0063] 1) Add (NH4)2MoS4 to DMF, sonicate for 10 min, stir for 30 min to obtain a DMF solution of (NH4)2MoS4 with a concentration of 3.8 mg / mL. Add CuCl2 to a sufficient amount of DMF solution that can completely dissolve CuCl2 and sonicate to obtain a DMF solution of CuCl2.

[0064] 2) Add CuCl2 DMF solution to (NH4)2MoS4 DMF solution at a copper-molybdenum molar ratio of 0.8:1, then sonicate and stir until homogeneous to obtain a mixed solution;

[0065] 3) The mixed solution was transferred to a polytetrafluoroethylene-lined stainless steel autoclave at a filling ratio of 53%. After solvothermal reaction in the autoclave at 185°C for 23 hours, the product was separated by centrifugation at 10,000 rpm for 5 minutes and washed three times with deionized water and ethanol to obtain Cu-MoS2 nanozymes with a Cu:Mo molar ratio of 0.8:1.

[0066] Example 8

[0067] 1) Add (NH4)2MoS4 to DMF, sonicate for 10 min, stir for 30 min to obtain a DMF solution of (NH4)2MoS4 with a concentration of 3.25 mg / mL. Add CuCl2 to a sufficient amount of DMF solution that can completely dissolve CuCl2 and sonicate to obtain a DMF solution of CuCl2.

[0068] 2) Add CuCl2 DMF solution to (NH4)2MoS4 DMF solution at a copper-molybdenum molar ratio of 0.6:1, then sonicate and stir until homogeneous to obtain a mixed solution;

[0069] 3) The mixed solution was transferred to a polytetrafluoroethylene-lined stainless steel autoclave at a filling ratio of 57%. After solvothermal reaction in the autoclave at 205°C for 24 hours, the product was separated by centrifugation at 10,000 rpm for 5 minutes and washed three times with deionized water and ethanol to obtain Cu-MoS2 nanozymes with a Cu:Mo molar ratio of 0.6:1.

[0070] Example 9

[0071] 1) Add (NH4)2MoS4 to DMF, sonicate for 10 min, stir for 30 min to obtain a DMF solution of (NH4)2MoS4 with a concentration of 3.75 mg / mL. Add CuCl2 to a sufficient amount of DMF solution that can completely dissolve CuCl2 and sonicate to obtain a DMF solution of CuCl2.

[0072] 2) Add CuCl2 DMF solution to (NH4)2MoS4 DMF solution at a copper-molybdenum molar ratio of 0.2:1, then sonicate and stir until homogeneous to obtain a mixed solution;

[0073] 3) The mixed solution was transferred to a polytetrafluoroethylene-lined stainless steel autoclave at a filling ratio of 54%. After solvothermal reaction in the autoclave at 220°C for 18 hours, the product was separated by centrifugation at 10,000 rpm for 5 minutes and washed three times with deionized water and ethanol to obtain Cu-MoS2 nanozymes with a Cu:Mo molar ratio of 0.2:1.

[0074] The products prepared in the examples were tested experimentally, and the results are as follows.

[0075] XRD spectra of Cu-MoS2 nanozymes at different concentrations demonstrate the retention of the MoS2 peak positions (e.g., Figure 1 (As shown). Furthermore, the increase in (010) intensity and the small angular migration of (110) indicate that the additional element was successfully introduced while the underlying MoS2 crystal structure was preserved.

[0076] ICP results (such as) Figure 2 As shown in the figure, the Cu content in the prepared sample is consistent with the molar ratio of Cu to Mo added during the preparation process. The results indicate that in DMF solution, Cu ions can coordinate with (NH4)2MoS4, and no polymerization or precipitation will occur in the aqueous solution system. The coordinated Cu can be successfully retained in Cu-MoS2.

[0077] Morphological images of Cu-MoS2 nanozymes with different Cu:Mo ratios (Cu:Mo = 10%, 30%, 50%, 70%, 90%) were observed by TEM (e.g., ...). Figure 3 As shown, with the increase of the Cu to Mo molar ratio, its morphology changed significantly. MoS2 without Cu dopant exhibited a plate-like stacked structure. Figure 3 a) When a portion of Cu element is incorporated (Cu:Mo = 10~50%), Figure 3 (b, c, d) Cu-MoS2 nanozymes exhibit a nanorod structure formed by self-assembled nanoflowers. When a large amount of Cu is incorporated (Cu:Mo = 70~90%), the structure shows improvement. Figure 3(e, f) The Cu-MoS2 nanozyme exhibits a hollow nanobox structure assembled from nanoflowers. This may be due to [Cu(DMF)] n During the solvothermal process, a solvation reaction occurs as the temperature increases. At this time, some CuCl2 may exist in a molecular state, or even precipitate cubic CuCl2 nanocrystals, becoming a growth template for Cu-MoS2. [Cu(DMF)] n The participation of the solvent causes the precipitated CuCl2 solvate to leave a hollow box structure, which opens up possibilities for subsequent applications of the material (such as drug loading).

[0078] The elemental distribution in the EDS spectrum of C3-M prepared in Example 1 was uniform (e.g., Figure 4 (as shown) Figure 4 (a) is a mixed elemental distribution diagram of Cu, Mo, and S in C3-M. Figure 4 (b, c, and d) correspond to the elemental distribution diagrams of Cu, Mo, and S, respectively, indicating that the method successfully prepared a uniform dispersion of Cu. As shown in Table 1, the molar ratio of S to Mo remained at approximately 2:1 and did not increase or decrease due to the addition of Cu, proving that no new Cu-related compounds were formed.

[0079] Table 1 shows the elemental ratios of MoS2 and Cx-M obtained by SEM combined with EDS.

[0080]

[0081] The prepared materials were further observed using HRTEM (e.g., Figure 5 (as shown) Figure 5 The HRTEM images corresponding to (a, a1)MoS2, (b, b1)C1-M, (c, c1)C3-M, (d, d1)C5-M, (e, e1)C7-M, and (f, f1)C9-M are shown in the figure. The lattice fringe width was measured to be 0.62 nm, belonging to the (002) crystal plane. In the figure, the width of the smaller fringe in the (100) crystal plane increased from 0.27 nm to 0.28 nm, which is consistent with the shift of the diffraction angle of the (110) crystal plane to a smaller angle in the XRD. With the increase of Cu addition, the connectivity of the (002) crystal plane groups became more complete, and it became increasingly difficult to observe the interruption in the figure, and it became easier to observe the base fringe in the figure. This was confirmed by the enhanced intensity of the (010) crystal plane in the XRD, which may be due to the chelation effect of Cu with (NH4)2MoS4, which promotes Cu to help MoS2 crystallize.

[0082] The POD activity of MoS2 and Cu-MoS2 nanozymes was analyzed by the change of absorbance over time in a TMB colorimetric experiment using MoS2 and Cu-MoS2 nanozymes prepared at different concentrations, and the Vo was calculated. max and K m The initial reaction rate of MoS2 and Cu-MoS2 nanozymes prepared at different concentrations with H2O2 was obtained by calculation, along with the substrate concentration. The calculated nanozyme kinetic parameters are shown in Table 2.

[0083] Table 2 Apparent Michaelis constants (K) of MoS2 and Cx-M m ), maximum reaction rate (V max ) and catalytic constant (k cat )

[0084]

[0085] Cu-MoS2 nanozymes with a copper-molybdenum molar ratio of 30% exhibit high Vo max and k cat This value indicates that the Cu-MoS2 nanozymes prepared within this ratio range exhibit the best catalytic performance. With the introduction of Cu, the catalytic sites on the material substrate become more abundant, and the entire catalytic process shifts to the Cu sites. At the same time, the morphology of Cu-MoS2 nanozymes with a 30% copper-molybdenum molar ratio does not change significantly, and its impact on substrate adsorption is relatively small. This is also the reason why Cu-MoS2 nanozymes with a 30% copper-molybdenum molar ratio have better overall kinetic parameters.

[0086] C3-M was observed using aberration-corrected scanning transmission microscopy (Ac-STEM). Based on the results and atomic images of Cu-MoS2, the basal plane ( Figure 6 (a) and its (002) crystal plane orientation ( Figure 6 (e) Select the S1, S2, and S3 regions, where Cu is densely distributed and well dispersed, for more detailed observation. In HAADF-STEM images, due to the nature of Z-contrast, elements with higher atomic numbers produce brighter signal intensity than elements with lower atomic numbers. At the same time, due to the difference in depth of field, the signal intensity of atoms with greater depth of field may be weakened.

[0087] Figure 6 (b) is a magnified view of the S1 selection area, in which you can see some relatively bright spots above the geometric center of the three Mo atoms. These bright spots are Cu atoms, and are marked with coils. Figure 6 (c) is a magnified view of the S2 selection area. It can be seen that some Cu atoms are located directly above the Mo atoms. The L1 box was used to select them, and the L2 box was used to select the Mo atoms in MoS2 without Cu atoms. Figure 6 (d) shows the atomic intensity distribution in L1 and L2. It can be seen that the maximum intensities of the two bright spots in L1 are almost identical, suggesting that the Cu atoms are in the same state. In L2, there is no significant difference in the maximum intensity, indicating that there is no Cu atom incorporation at that location. Meanwhile, to rule out the possibility that this phenomenon is a result of MoS2 layer growth, the orientation of the (002) crystal plane was observed. In the S3 region ( Figure 6 (f) Numerous bright spots were observed between the MoS2 layers, and their states varied. Some bright spots were directly above the Mo atoms (solid line circles), while others were slightly shifted (dashed line circles). Combined with modeling observations ( Figure 6 (g) In Cu-MoS2, Cu atoms have two possible positions. The first is that Cu is at the symmetry center of the three S atoms, perpendicular to the Mo atoms. The second is that Cu is at the symmetry center of the three Mo atoms, but not above the Mo atoms. Rotating the model to the (002) direction reveals that the Cu atom directly above the Mo atoms remains directly above them from this perspective, while the Cu atom at the geometric center of the three Mo atoms is slightly offset and not directly above the Mo atoms. This is consistent with the situation in the magnified detail of the S3 region, where there is some offset when observed in the (002) direction. This positional relationship remains consistent regardless of model rotation in this crystal plane observation direction, indicating that Cu is atomically dispersed in MoS2 and the dispersion is relatively uniform. Furthermore, studies have shown that Cu sites are highly favorable for the adsorption and desorption of H atoms, making it easier for H2O2 to adsorb and desorb at Cu sites, thus enhancing the activity of the POD enzyme.

[0088] Figure 7 The SOD-like activity after treatment with Cu-MoS2 nanozymes prepared at different concentrations and using the NBT optical method was measured. Figure 8 As shown, Cu-MoS2 nanozymes with a copper-molybdenum molar ratio of 30-70% still maintain low absorbance after light irradiation, while Cu-MoS2 nanozymes with a copper-molybdenum molar ratio of 90% have relatively good low absorbance.

[0089] Calculate the superoxide anion scavenging rate (e.g.) Figure 8 After further analysis, it was found that Cu-MoS2 nanozymes with a copper-molybdenum molar ratio of 70% exhibited excellent superoxide anion removal efficiency, reaching 91.40%, followed by Cu-MoS2 nanozymes with a copper-molybdenum molar ratio of 30-50%, at approximately 90%. The removal efficiency of Cu-MoS2 nanozymes with a copper-molybdenum molar ratio of 90% decreased to 60.47%. This may be attributed to the decrease in specific surface area with changes in morphology and Cu content.

[0090] After the NBT light exposure experiment, take reaction photos of each sample treatment (e.g., Figure 9 This study aimed to more closely observe the excellent SOD-like activity of MoS2 and Cu-MoS2 nanozymes prepared at different concentrations. Notably, neither MoS2 nor Cu-MoS2 nanozymes with a 10% copper-molybdenum molar ratio exhibited strong SOD-like activity. XPS analysis suggested that the bond between Cu and MoS2 is a special state. The migration of Cu electron clouds to S and Mo makes it easier for Cu to gain electrons, while Mo more easily loses electrons, which may endow it with SOD activity. During the reaction, Cu... 2+ With •O 2- It combines to gain an electron and is oxidized to oxygen, while Mo 4+ With •O 2- Cu loses an electron and is reduced to H₂O₂. In the final stage of the reaction, Cu transfers the gained electron to a Mo atom through its electron cloud overlapping with Mo and S. Cu and Mo then return to their ground state, completing the catalytic process.

[0091] As the Cu concentration decreased, the GSH scavenging rate decreased from 83.18% to 82.71%. Figure 10 As shown. However, with increasing Cu concentration, the GSH-OXD-like activity increased again. The Cu-MoS2 nanozyme with a copper-molybdenum molar ratio of 90% exhibited the strongest GSH-OXD-like activity, with a maximum GSH scavenging rate of 91.49%. In addition, the GSH scavenging rates of other samples were all above 80%. This is because the addition of a small amount of Cu occupies the active sulfur sites at the edge of MoS2. Although Cu is an excellent GSH scavenging site, it may not be as effective as sulfur sites, leading to a decrease in performance at low concentrations. However, with further introduction of Cu, the (002) crystal plane of MoS2 is activated, and the Cu sites make a significant contribution to the performance improvement.

[0092] Figure 11 The images show the growth of Staphylococcus aureus. Staphylococcus aureus was treated with Cu-MoS2 nanozymes prepared at 50 μg / mL MoS2 and different concentrations, both with and without H2O2. Figure 11 As can be seen from (ag), in the absence of H2O2, both MoS2 and Cu-MoS2 nanozymes prepared at different concentrations exhibit limited antibacterial properties. Among them, Cu-MoS2 nanozymes with a copper-molybdenum molar ratio of 20-40% showed the best antibacterial effect, with an antibacterial rate of 65-68%. Cu-MoS2 nanozymes with a copper-molybdenum molar ratio of 60% also showed good antibacterial performance, with an antibacterial rate of 50.5%. The antibacterial rates of other samples were all below 30%. However, with the addition of 0.1 mM H2O2, the antibacterial properties of Cu-MoS2 nanozymes prepared at different concentrations were significantly improved, such as... Figure 11As shown in Figures a1-g1, this is attributed to the POD-like activity of the Cu-MoS2 nanozyme, which catalyzes the conversion of H2O2 into •OH. The generated •OH attacks the bacterial biomolecules, leading to bacterial death. The figure shows that the Cu-MoS2 nanozyme with a copper-molybdenum molar ratio of 30% exhibits the best antibacterial effect, achieving an antibacterial rate of over 99%. Cu-MoS2 nanozymes with a copper-molybdenum molar ratio of 50-90% achieve an antibacterial rate of over 90%, and the antibacterial rate of Cu-MoS2 nanozymes with a copper-molybdenum molar ratio of 10% also increases to 66.9%.

Claims

1. A method for controlling the catalytic activity and morphology of Cu-MoS2 nanozymes by adjusting the copper content, characterized in that, A mixed solution was obtained by adding a DMF solution of CuCl2 to a DMF solution of (NH4)2MoS4, followed by sonication and stirring. The mixed solution was then subjected to a solvothermal reaction in an autoclave at 180–220 °C for 18–24 hours. The product was then separated by centrifugation and washed to obtain Cu-MoS2 nanozyme. When the copper-molybdenum molar ratio is 0.1–0.5:1, Cu-MoS2 nanozymes exhibit a nanorod structure formed by self-assembled nanoflowers. When the copper-molybdenum molar ratio is 0.7–0.9:1, Cu-MoS2 nanozymes exhibit a hollow nanobox structure assembled from nanoflowers. When the copper-molybdenum molar ratio is 0.3:1, the prepared Cu-MoS2 nanozyme exhibits peroxidase-like activity. When the copper-molybdenum molar ratio is 0.7:1, the prepared Cu-MoS2 nanozyme exhibits superoxide dismutase-like activity; when the copper-molybdenum molar ratio is 0.9:1, the prepared Cu-MoS2 nanozyme exhibits glutathione oxidase-like activity.

2. The method for controlling the catalytic activity and morphology of Cu-MoS2 nanozymes by adjusting the copper content as described in claim 1, characterized in that, The (NH4)2MoS4 DMF solution is prepared by adding (NH4)2MoS4 to DMF, sonicating for 10 min, and stirring for 30 min to obtain a (NH4)2MoS4 DMF solution with a concentration of 3-4 mg / mL.

3. The method for controlling the catalytic activity and morphology of Cu-MoS2 nanozymes by adjusting the copper content as described in claim 1, characterized in that, The CuCl2 DMF solution is obtained by adding CuCl2 to a sufficient amount of DMF solution that can completely dissolve CuCl2 and then ultrasonically stirring.

4. The method for controlling the catalytic activity and morphology of Cu-MoS2 nanozymes by adjusting the copper content as described in claim 1, characterized in that, The autoclave is a stainless steel autoclave lined with polytetrafluoroethylene.

5. The method for controlling the catalytic activity and morphology of Cu-MoS2 nanozymes by adjusting the copper content as described in claim 1, characterized in that, The reaction filling rate of the solvothermal reaction is 50-60%.

6. The method for controlling the catalytic activity and morphology of Cu-MoS2 nanozymes by adjusting the copper content as described in claim 1, characterized in that, The centrifugation process involves separating the product by centrifuging at 10,000 rpm for 5 minutes, followed by washing three times with deionized water and ethanol.

Images