Nano mimetic enzyme as well as preparation method and application thereof

Abstract

The invention discloses a nano mimetic enzyme as well as a preparation method and application thereof. The nano-mimic is of a nano-cloud structure formed by stacking irregular spheres and rods, and the nano-cloud structure is a one-dimensional, two-dimensional or three-dimensional system. The preparation method of the nano mimic enzyme comprises the following steps: 1) dissolving a copper salt and a manganese salt in deionized water to obtain a mixed solution; 2) adding hydrogen peroxide into the mixed solution to obtain a Cu < 2 + > / Mn < 3 + > mixed solution A; 3) adding the alkaline solution B into the Cu < 2 + > / Mn < 3 + > mixed solution A, stirring and mixing to obtain a mixed brown turbid solution, and standing and aging; and (4) precipitating and separating the aged turbid liquid in the step (3), cleaning, drying and grinding to obtain the nano mimic enzyme. The nano mimetic enzyme suspension is applied to watermelon seed priming. The nano enzyme mimetic suspension disclosed by the invention is applied to preparation of antibacterial drugs. The nano mimic enzyme can promote seed germination and growth, and has a remarkable inhibition effect on watermelon bacterial germs, namely fruit blotch germs or watermelon fungal germs, namely wilt germs.

Description

Technical Field

[0001] The invention belongs to the field of agriculture and relates to a nano-mimetic enzyme and a preparation method and application thereof. Background Art

[0002] As one of the most widely planted horticultural crops in the world, watermelon occupies an important position in fruit production and consumption. In China, watermelon production is absolutely dominant, and China is one of the world's major watermelon producers. According to the FAO database, in 2018, the global watermelon harvest area and production ranked among the top in the world, and the production ranked first in the world's fruit production. At present, watermelon seed germination and disease problems are important factors affecting watermelon yield and quality. In addition to watermelon, these problems also exist in crops such as corn in monocotyledonous plants and cotton and tomatoes in dicotyledonous plants.

[0003] In this context, it is particularly important to conduct in-depth research on these problems and find solutions. Therefore, we turned our attention to the nanotechnology industry. At present, Cu-based nanomaterials are easily oxidized in the air, resulting in changes in surface properties and affecting their application performance; Mn-based nanomaterials have poor dispersion in water, which will limit their use. The effects of these two nanomaterials used alone are unstable and the cost is high, making them difficult to promote and use. Summary of the invention

[0004] In order to solve at least one of the above technical problems, the purpose of the present invention is to provide a nano-enzyme for promoting seed germination, a preparation method and an application.

[0005] The invention provides a nano-enzyme, wherein the nano-enzyme is in a nano-cloud structure composed of irregular spherical and rod-shaped stacks; the nano-cloud structure is a one-dimensional, two-dimensional or three-dimensional system.

[0006] In the above-mentioned nanoenzyme, the nanoenzyme contains Cu, Mn, and O elements. The molar ratio of the Cu element in the nanoenzyme can be 70-90%, the molar ratio of the Mn element is 10-30%, the molar ratio of the O element is 0.5-1%, and the molar ratio of the Mn element to the Cu element is 1:4; the nanoenzyme contains residual C, S, and H elements, and their molar ratio is 0-1%.

[0007] In the present invention, the nanoenzyme CuMn-LDHs has the characteristics of large specific surface area, uniform metal ion composition, good thermal stability, excellent synergistic effect, etc.

[0008] In the present invention, the layered oxide nanoenzyme CuMn-LDHs particles have antibacterial properties, and the antibacterial carrier is LDH. LDH itself contains mineral components that have an inhibitory effect on some microorganisms. At the same time, the LDH microstructure has abundant voids and surface areas, and has extremely strong adsorption, which can improve and maintain the stability and durability of the antibacterial agent as well as high activity; the copper in the CuMn-LDHs particles has antibacterial and antimicrobial properties, and the copper ions have the ability to kill bacteria, viruses and other microorganisms; the manganese in the CuMn-LDHs particles is an important antioxidant, which has a positive effect on cell protection and resistance to oxidative damage, but in some cases may also have a certain impact on the survival and reproduction of some microorganisms.

[0009] In the present invention, the composition and structure of the nano-enzyme CuMn-LDHs are controllable. The CuMn-LDHs nanoparticles do not have a fixed chemical composition. The element types and composition ratios of the main layer plates, the types and quantities of interlayer anions, and the two-dimensional pore structure can be adjusted in a wide range as needed to obtain materials with special structures and properties; changing its composition and structure can change the color of CuMn-LDHs.

[0010] The present invention provides a method for preparing the above-mentioned nano-enzyme mimetic, comprising the following steps:

[0011] 1) dissolving copper salt and manganese salt in deionized water to obtain a mixed solution;

[0012] 2) Adding hydrogen peroxide to the mixed solution to obtain Cu 2+ / Mn 3+ Mixed solution A;

[0013] 3) Add alkaline solution B to the Cu 2+ / Mn 3+ The mixed solution A was stirred to obtain a mixed brown turbid solution, and then allowed to stand for aging;

[0014] 4) The precipitate of the aged turbid liquid in step 3) is separated, washed, dried and ground to obtain the nano-mimetic enzyme.

[0015] In the above preparation method, the copper salt is selected from at least one of copper sulfate, copper chloride and copper nitrate;

[0016] The manganese salt is manganese sulfate and / or manganese chloride;

[0017] The molar ratio of copper to manganese in the copper salt and the manganese salt may be 2.5 to 3.5:1, specifically 3:1.

[0018] In the present invention, the copper salt and the manganese salt are preferably copper nitrate and manganese sulfate.

[0019] In the above preparation method, the alkaline solution B is a solution containing OH - The alkali and carbonate or bicarbonate are added to deionized water and dissolved;

[0020] The OH-containing - The mass ratio of the alkali to the carbonate or bicarbonate may be 1:0.8-1.5;

[0021] The OH-containing - The base includes sodium hydroxide or potassium hydroxide, the carbonate includes sodium carbonate or potassium carbonate, and the bicarbonate includes sodium bicarbonate or potassium bicarbonate.

[0022] In the present invention, the alkaline solution B is preferably prepared by dissolving sodium hydroxide and sodium bicarbonate, sodium hydroxide and potassium carbonate, sodium hydroxide and potassium bicarbonate, potassium hydroxide and sodium carbonate, potassium hydroxide and sodium bicarbonate, potassium hydroxide and potassium bicarbonate in deionized water.

[0023] In the above preparation method, in step 3), in step 3), the dropping speed of the alkaline solution B is 5 to 15 mL / min, specifically 10 mL / min, 5 to 10 mL / min, 10 to 15 mL / min;

[0024] The stirring rate may be 450-750 rpm, specifically 500 rpm, 450-500 rpm, 500-750 rpm;

[0025] In step 3), the static aging time can be 2h to 12h, specifically 7h, 2h to 7h, 7h to 12h. The change of aging time can control the size of the nano-enzyme.

[0026] In the above preparation method, in step 4), the washing is carried out using deionized water;

[0027] The drying temperature may be 60-80°C, specifically 80°C or 70-80°C.

[0028] The present invention also provides the nano-enzyme prepared by the above method.

[0029] The present invention also provides a nano-enzyme mimetic suspension, which is an aqueous suspension of the nano-enzyme mimetic, wherein the nano-enzyme mimetic is dispersed in the aqueous phase of the suspension.

[0030] In the present invention, the concentration of the nano-enzyme in the suspension is saturated or slightly precipitated.

[0031] The nano-mimetic enzyme suspension of the present invention is applied to watermelon seed priming.

[0032] In the above application, the watermelon seed priming is to promote the germination and growth rate of watermelon seeds; the concentration of the nano-mimetic enzyme suspension can be 200±5 mg / L.

[0033] The nano-mimetic enzyme suspension of the present invention is used in preparing medicines for inhibiting watermelon bacterial pathogens such as fruit spot pathogens or watermelon fungal pathogens such as wilt pathogens.

[0034] In the above application, the minimum effective concentration of the nano-mimetic enzyme CuMn-LDHs suspension in the medicine can be 200±5 mg / L.

[0035] In the present invention, the medicine for inhibiting the watermelon fungal pathogen Fusarium wilt is a medicine for inhibiting the growth morphology of the watermelon fungal pathogen Fusarium wilt and reducing the number of spores.

[0036] The present invention has the following beneficial effects:

[0037] (1) The bactericidal properties of CuMn-LDHs and their effectiveness in preventing and controlling watermelon fruit spot are due to the fact that the LDH antimicrobial carrier can improve the stability of the antimicrobial agent, prolong its durability, and maintain the high activity of the antimicrobial agent; copper ions have the ability to kill bacteria, viruses, and other microorganisms; the antioxidant properties of manganese have a positive effect on cell protection and resistance to oxidative damage, but sometimes also have an impact on bacterial colonies; in addition, CuMn-LDHs also have properties such as controllable composition and structure, catalytic properties, infrared absorption properties, flame retardancy, memory effect, and thermal stability.

[0038] (2) Using CuMn-LDHs, which is similar to copper and manganese fertilizers, the nanoenzyme is dissolved in water to form a suspension. At a concentration of about 200±5mg / L, it can effectively promote the germination of various crop seeds and the growth of subsequent seedlings. At a concentration of 200±5mg / L, the nanoenzyme can play the role of a catalyst to increase the activity of plant antioxidant enzymes and improve plant stress resistance.

[0039] (3) The composition and structure of the nanoenzyme CuMn-LDHs of the present invention are adjustable, resulting in changes in the function of CuMn-LDHs as the composition and structure change, making CuMn-LDHs a new type of material with great research potential and application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is the TEM image of the CuMn-LDHs nanoenzyme mimicking material of Example 1; Figure 1 In the figure, a, b, c, d, and e are detailed images of the nanozymes at sizes of 0.5 μm, 2 μm, 1 μm, and 500 nm, respectively, and vector diagrams of the diameters of irregular spherical and rod-shaped nanoparticles in the nanozymes, and e represents a vector.

[0041] Figure 2 The EDS spectra and quantitative results of the CuMn-LDHs nanoenzyme material in Example 1; Figure 2 a is the EDS spectrum, and b is the quantitative results of Cu, Mn and O.

[0042] Figure 3 This is the XRD crystallization effect diagram. Figure 3 Where A is the angle between the crystal plane and the X-ray (2θ); B is the diffraction peak intensity (reflecting the diffraction ability of the corresponding crystal plane).

[0043] Figure 4 This is a diagram showing the effect of CuMn-LDHs nanoenzyme seed initiation in Example 5 of the present invention; Figure 4 a~h in the middle are comparison charts of priming effect, germination rate, overall seedling effect, seedling effect, fresh weight, dry weight, root length, and stem height, respectively.

[0044] Figure 5 This is a diagram showing the effect of CuMn-LDHs nanoenzyme seed initiation in Example 6 of the present invention; Figure 5 a~h in the middle are comparison charts of priming effect, germination rate, overall seedling effect, seedling effect, fresh weight, dry weight, root length, and stem height, respectively.

[0045] Figure 6 This is a diagram showing the effect of CuMn-LDHs nanoenzyme seed initiation in Example 7 of the present invention; Figure 6 a~h in the middle are comparison charts of priming effect, germination rate, overall seedling effect, seedling effect, fresh weight, dry weight, root length, and stem height, respectively.

[0046] Figure 7 This is a diagram showing the effect of CuMn-LDHs nanoenzyme seed initiation in Example 8 of the present invention; Figure 7 a~h in the middle are comparison charts of priming effect, germination rate, overall seedling effect, seedling effect, fresh weight, dry weight, root length, and stem height, respectively.

[0047] Figure 8 This is a diagram showing the inhibitory effect of CuMn-LDHs on watermelon fruit spot pathogen in Example 9 of the present invention.

[0048] Fig. 9 This is a graph showing the inhibitory effect of CuMn-LDHs on watermelon wilt pathogen in Example 10 of the present invention; Fig. 9 In the middle, a and b are the antibacterial effect diagram of the plate and the comparison diagram of the number of spores under the electron microscope, respectively. DETAILED DESCRIPTION

[0049] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0050] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0051] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0052] The present invention is further described in detail below in conjunction with specific embodiments.

[0053] Example 1

[0054] This embodiment provides a solid nanoenzyme and a preparation method thereof, and the specific operation is as follows: a CuMn-LDHs precursor with a copper-manganese molar ratio of 3:1 is prepared at room temperature by a coprecipitation method.

[0055] (1) Dissolution of copper nitrate trihydrate and manganese sulfate monohydrate: 14.496 g of copper nitrate trihydrate and 3.3804 g of manganese sulfate monohydrate were dissolved in 200 mL of deionized water.

[0056] (2) Solution A: After the solid is completely dissolved, add an appropriate amount of hydrogen peroxide (H2O2, 10 mL) to oxidize the divalent manganese ions into trivalent manganese to prepare a Cu2+ / Mn3+ mixed solution A; at the same time, prepare an alkaline solution B.

[0057] (3) Alkaline solution B: Weigh 5.12 g of sodium hydroxide and 4.2396 g of sodium carbonate and add them to 200 mL of deionized water to prepare alkaline solution B.

[0058] (4) Mixing A and B: Stir solution A at 500 rpm, and at the same time, slowly drip alkaline solution B into solution A in a dropping funnel (dropping speed 10 mL / min). After solution B is completely added to solution A, stop stirring, and then age the mixed brown turbid solution at room temperature overnight for 7 h.

[0059] (5) Precipitation, separation, drying, and grinding: After aging, the turbid liquid was allowed to settle and the supernatant was discarded. A sufficient amount of deionized water was added for washing (repeated 3 times). After washing, the CuMn-LDHs precipitate was separated using a vacuum filtration device and then placed in an oven at 80°C for drying. After it was completely dried, it was taken out and ground into powder using a mortar and pestle, and then bagged for later use.

[0060] The solid nanozyme prepared above was tested by TEM, and its particle size was 1692±100nm. TEM images of nanozyme at 0.5μm, 2μm, 1μm, and 500nm sizes, as well as the vector diagrams of the diameters of irregular spherical and rod-shaped nanoparticles in the nanozyme, as shown in Figure 1 The energy spectrum of the composite material shows that the solid nanoenzyme prepared above mainly contains Cu (79.67%), Mn (19.39%), O (0.61%) elements, and residual C, S, and H elements (the residual molar ratio is 0.33%). Figure 2 As shown. XRD results show that the sample has low crystallinity, such as Figure 3 shown.

[0061] Example 2

[0062] In this example, the nanomaterial prepared in Example 1 was subjected to a water solubility experiment, and the specific operation was as follows:

[0063] 150 mg of nanomaterials were dispersed in 15 ml of pure water and shaken by hand for 30 min (recorded as treatment 1), and then left to stand for 1 h to observe whether precipitation occurred.

[0064] 150 mg of nanomaterials were dispersed in 15 ml of pure water and shaken on a shaker at 37°C for 30 min (referred to as treatment 2). After standing for 1 h, the nanomaterials were observed to see if any precipitation occurred.

[0065] 150 mg of nanomaterials were dispersed in 15 ml of pure water using an ultrasonic cell disruptor at 0.2 kW for 30 min (referred to as treatment 3), and then allowed to stand for 1 h to observe whether precipitation occurred.

[0066] Table 1 Water solubility test results of nanomaterials in Examples and Comparative Examples

[0067] Nanomaterials Dispersibility Precipitation Process 1 Dispersible There is precipitation, a lot of precipitation and it is concentrated Process 2 Dispersible There is precipitation, a lot of precipitation and it is concentrated Process 3 Dispersible There is precipitation, little precipitation and it is dispersed

[0068] From the results in Table 1, it can be seen that the suspensions prepared by the three treatments all have precipitation, and the precipitation of treatment 3 is slower than that of treatment 1 and treatment 2; after re-shaking, the precipitation of the three treatments is quickly suspended, and the suspension speed of treatment 3 is faster; and the precipitation after treatment 3 is more dispersed at the bottom, while the precipitation of treatment 1 and treatment 2 is more concentrated; it is recommended to use the suspension prepared by treatment 3, and shake it while using it.

[0069] Example 3

[0070] This example will provide the configuration method in Example 2 Process 3 to prepare CuMn-LDHs with a concentration of 200 mg / L. The specific operations are as follows:

[0071] The nano-mimetic enzyme suspension was prepared according to the method in treatment 3 of Example 2. 100 mg of CuMn-LDHs powder was added to a beaker containing 500 ml of sterile water, and treated with an ultrasonic cell disruptor at 0.2 kW for 30 min and set aside.

[0072] Example 4

[0073] This example provides a method for nano solution seed initiation in Example 3, and the specific steps are as follows:

[0074] The nano suspension in Example 3 and different crop seeds for seed priming are prepared for use, 25 seeds / 50 seeds are repeated for one time according to the seed conditions, and each seed is repeated 4 times. The wrapped seeds are soaked in the prepared nano suspension, stirred every 3 hours, and the seeds are fished out after 12 hours and dried for use.

[0075] Example 5

[0076] This embodiment provides a method for accelerating germination of watermelon seeds primed in Example 4, and the specific steps are as follows:

[0077] The watermelon seeds primed in Example 4 are prepared for use, and the germination experiment is carried out according to the national standard for the inspection of crop seeds (GB / T 3543.4-1995), wherein the watermelon germination method in this example is sand culture. Sand culture: 50 watermelon seeds are evenly sown on a layer of flat wet sand, and then covered with a layer of loose sand with a thickness of 10-20 mm according to the size of the seeds, and the experiment is repeated three times. Preparation of sand bed: The sand particles are uniform in size, with a diameter of 0.05-0.80 mm. The sand is washed and sterilized with high temperature before use. 1000g of sand is added with 160ml of sterile water and mixed, and evenly spread in the germination box with a thickness of about 2cm. The temperature in the artificial climate box is set at (25±1)℃, the humidity is 85%, the light intensity is 10000Lx and the light treatment is 16h / 8h (light / dark), and the cultivation is carried out for a total of 14 days. The radicle breaking through the seed coat is taken as the seed germination standard, and the germination and seedling growth are counted. As Figure 4 It shows that nanomaterials can effectively improve the germination rate of watermelon seeds as well as the fresh weight, dry weight, plant height and root length of watermelon seedlings.

[0078] Example 6

[0079] This embodiment provides a method for accelerating germination of corn seeds primed in Example 4, and the specific steps are as follows:

[0080] The primed corn seeds in Example 4 are prepared for use, and the germination experiment is carried out according to the national standard for the inspection of crop seeds (GB / T 3543.4-1995), wherein the corn germination method in this example is sand culture. Sand culture: 50 corn seeds are evenly sown on a layer of flat wet sand, and then covered with a layer of loose sand with a thickness of 10-20 mm according to the size of the seeds, and the experiment is repeated three times. Preparation of sand bed: The sand particles are uniform in size, with a diameter of 0.05-0.80 mm. The sand is washed and sterilized at high temperature before use. 1000g of sand is mixed with 160ml of sterile water, and evenly spread in the germination box with a thickness of about 2cm. The temperature in the artificial climate box is set at (25±1)℃, the humidity is 85%, the light intensity is 10000Lx and the light treatment is 16h / 8h (light / dark), and the cultivation is carried out for a total of 14 days. The radicle breaking through the seed coat is taken as the seed germination standard, and the germination and seedling growth are counted. As shown in Table 3, Figure 5 It is shown that nanomaterials can effectively improve the germination rate of corn seeds and the fresh weight, dry weight, plant height and root length of corn seedlings.

[0081] Example 7

[0082] This embodiment provides a method for accelerating germination of cotton seeds primed in Example 4, and the specific steps are as follows:

[0083] The primed cotton seeds in Example 4 are prepared for use, and the germination experiment is carried out according to the national standard for the inspection of crop seeds (GB / T 3543.4-1995), wherein the cotton germination method in this example is sand culture. Sand culture: 50 cotton seeds are evenly sown on a layer of flat wet sand, and then covered with a layer of loose sand with a thickness of 10-20 mm according to the size of the seeds, and the experiment is repeated three times. Preparation of sand bed: The sand particles are uniform in size, with a diameter of 0.05-0.80 mm. The sand is washed and sterilized with high temperature before use. 1000g of sand is added with 160ml of sterile water and mixed, and evenly spread in the germination box with a thickness of about 2cm. The temperature in the artificial climate box is set at (25±1)℃, the humidity is 85%, the light intensity is 10000Lx and the light treatment is 16h / 8h (light / dark), and the cultivation is carried out for a total of 14 days. The radicle breaking through the seed coat is taken as the seed germination standard, and the germination and seedling growth are counted. As Figure 6 It is shown that nanomaterials can effectively improve the germination rate of cotton seeds and the fresh weight, dry weight, plant height and root length of cotton seedlings.

[0084] Example 8

[0085] This example provides a method for accelerating germination of tomato seeds primed in Example 4, and the specific steps are as follows:

[0086] Prepare the tomato seeds primed in Example 4 for use, and conduct a germination experiment according to the national standard for the inspection of crop seeds (GB / T 3543.4-1995), wherein the tomato germination method in this example is paper culture. Paper culture: 50 tomato seeds are evenly sown in a flat wet paper box, using filter paper or absorbent paper with a certain strength, good texture, strong water absorption, good water retention, non-toxic and sterile, clean, free of soluble pigments or other chemicals, and a pH value of 6.0-7.5; put the prepared absorbent paper into the germination box and add water, so that it is moist to the touch and no water flows when inverted. The temperature in the artificial climate box is set at (25±1)℃, humidity at 85%, light intensity at 10000Lx, and light treatment at 16h / 8h (light / dark), and the cultivation is carried out for a total of 14 days. The germination standard is that the radicle breaks through the seed coat, and the germination and seedling growth are counted. Figure 7 It shows that nanomaterials can effectively improve the germination rate of tomato seeds and the fresh weight, dry weight, plant height and root length of tomato seedlings.

[0087] Example 9

[0088] This example provides the combination of the suspension prepared in Example 2 with a nutrient broth (NB) solid culture medium and the inhibitory effect on fruit spot pathogens. The specific operation is as follows:

[0089] A 10 g / L nano-enzyme suspension was prepared according to Example 2. The suspension was divided into five portions of different volumes: 0, 1, 2, 3, 4, and 5 ml in a clean bench. Then 45 ml of unsolidified NB culture medium (with antibiotics AMP) was added to each portion. + ), pure water was adjusted to 50 ml, poured into the culture dish, and allowed to stand for 30 minutes to prepare NB solid medium containing different concentrations of nano-enzyme 0, 200, 400, 600, 800, 1000 mg / L, and the treatment with 0 mg / L was the control treatment. Use an inoculation loop to dip the activated watermelon fruit spot disease strain Xu3-14, draw a 1 cm line in the center of the culture dish, seal it, and culture it at 28°C for 1 day to observe the growth.

[0090] The results are as follows Figure 8 As shown, compared with the control treatment, the NB solid culture medium containing nano-mimetic enzyme concentration greater than 200 mg / L can effectively inhibit the growth of fruit spot pathogens.

[0091] Example 10

[0092] This example provides the combination of the suspension prepared in Example 2 with a nutrient broth (NB) solid culture medium and the inhibitory effect on fruit spot pathogens. The specific operation is as follows:

[0093] A 10 g / L nano-enzyme suspension was prepared according to Example 2. The suspension was divided into five portions of different volumes: 0, 1, 2, 3, 4, and 5 ml in a clean bench. Then 45 ml of unsolidified PDA culture medium (with antibiotic AMP) was added to each portion. + ), pure water was adjusted to 50 ml, poured into the culture dish, and allowed to stand for 30 min to prepare PDA solid culture medium containing different concentrations of nano-enzyme 0, 200, 400, 600, 800, 1000 mg / L, and the treatment with 0 mg / L was the control treatment. Use an 8 mm puncher to transfer the bacterial cake into the culture medium with different treatments.

[0094] The results are as follows Fig. 9 As shown, compared with the control treatment, the PDA solid culture medium containing nanomimetic enzymes at a concentration greater than 200 mg / L changed the physiological morphology of Fusarium wilt and significantly reduced the number of sporangia.

[0095] It is necessary to point out that the above embodiments are limited to further elaboration and explanation of the technical solution of the present invention, and are not further limitations of the technical solution of the present invention. The method of the present invention is only a preferred implementation scheme, and is not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A nano-enzyme, characterized in that: The nano-enzyme mimetic is in a nano-cloud structure composed of irregular spherical and rod-shaped stacks, and the nano-cloud structure is a one-dimensional, two-dimensional or three-dimensional system.

2. The nanoenzyme according to claim 1, characterized in that The nano-mimetic enzyme contains Cu, Mn and O elements, wherein the molar ratio of Cu element in the nano-mimetic enzyme is 70-90%, the molar ratio of Mn element is 10-30%, the molar ratio of O element is 0.5-1%, and the molar ratio of Mn element to Cu element is 1:4; the nano-mimetic enzyme contains residual C, S and H elements, and the molar ratio thereof is 0-1%.

3. The method for preparing the nano-enzyme according to claim 1 or 2, characterized in that: The steps include: 1) dissolving copper salt and manganese salt in deionized water to obtain a mixed solution; 2) Adding hydrogen peroxide to the mixed solution to obtain Cu 2+ / Mn 3+ Mixed solution A; 3) Add alkaline solution B to the Cu 2+ / Mn 3+ The mixed solution A was stirred to obtain a mixed brown turbid solution, and then allowed to stand for aging; 4) The precipitate of the aged turbid liquid in step 3) is separated, washed, dried and ground to obtain the nano-mimetic enzyme.

4. The preparation method according to claim 3, characterized in that: The copper salt is selected from at least one of copper sulfate, copper chloride and copper nitrate; The manganese salt is manganese sulfate and / or manganese chloride; The molar ratio of copper to manganese in the copper salt and the manganese salt is 2.5 to 3.5:1; The alkaline solution B contains OH - The alkali and carbonate or bicarbonate are added to deionized water and dissolved; The OH-containing - The mass ratio of the alkali to the carbonate or bicarbonate is 1:0.8-1.5; The OH-containing - The base includes sodium hydroxide or potassium hydroxide, the carbonate includes sodium carbonate or potassium carbonate, and the bicarbonate includes sodium bicarbonate or potassium bicarbonate.

5. The preparation method according to claim 3 or 4, characterized in that: In step 3), the dropping speed of the alkaline solution B is 5 to 15 mL / min; The stirring rate is 450-750 rpm; In step 3), the static aging time is 2h to 12h; In step 4), the cleaning is performed using deionized water; The drying temperature is 60-80°C.

6. The nanoenzyme prepared by the preparation method according to claims 3-5.

7. A nano-enzyme suspension, characterized in that: The nano-enzyme suspension is an aqueous suspension of the nano-enzyme according to claim 1 or 2, wherein the nano-enzyme is dispersed in the aqueous phase of the suspension.

8. The use of the nano-enzyme suspension according to claim 7 in watermelon seed priming, characterized in that: The nano-mimetic enzyme promotes the germination growth rate of watermelon seeds, and the concentration of the nano-mimetic enzyme suspension is 200±5 mg / L.

9. Use of the nano-enzyme suspension according to claim 7 in the preparation of antibacterial drugs.

10. The use according to claim 9, characterized in that: The antibacterial drugs include drugs that inhibit watermelon bacterial pathogens such as fruit spot pathogens or watermelon fungal pathogens such as wilt pathogens.

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