A responsive nanopesticide delivery system and its preparation method and application

Abstract

The present invention establishes a pyraclostrobin-methyl thiophanate dual-drug pH-responsive nanopesticide delivery system encapsulated with copper ions and natural product tannic acid coordination complexes, which is used to control the release of pyraclostrobin and thiophanate methyl. The nano delivery system of the present invention has a loading capacity of more than 92% for fungicides, has significantly improved photostability, and is 85 times that of commercially available pyraclostrobin. The responsive nanopesticide delivery system can improve the deposition efficiency and adhesion ability on crop leaves. Under natural conditions, the long-term control efficiency is 5.9 times that of commercially available suspensions, and has a controlled release effect, realizing the fixed-point targeted release of fungicides. Therefore, the responsive nanopesticide delivery system in the present invention has great potential in enhancing the targeting and persistence of active ingredients, has a simple preparation process, is green and controllable, and is suitable for industrial large-scale production.

Description

Technical Field

[0001] The invention belongs to the technical field of pesticides and relates to a responsive nano pesticide delivery system and a preparation method and application thereof. Background Art

[0002] Pesticides are widely used to control the occurrence and spread of plant diseases, pests, and weeds in modern agriculture, effectively improving crop yields and quality. However, only 0.1% of the active ingredients reach the harmful biological targets, while 90-99.9% of the active ingredients are lost to the surrounding environment due to droplet drift, biodegradation, surface runoff, photolysis, and evaporation. The low efficiency of pesticide use has caused several adverse effects on the environment, such as water and soil pollution, increased resistance of target organisms, and reduced biodiversity. Encapsulation of pesticides in polymer carriers provides a new approach to improve their utilization efficiency by minimizing the risks of pesticides to the environment, which can reduce degradation, enhance stability, reduce non-target toxicity, and effectively prolong the persistence of pesticides. The construction of stimulus-responsive release pesticide delivery systems such as enzymes, pH, temperature, and light can maximize the synergistic effect of pesticide release characteristics and pest control dosage requirements. Unfortunately, the release rate of active ingredients in pesticide microcapsules is difficult to control, and most polymer shells used to prepare pesticide microcapsules can induce secondary pollution in the environment.

[0003] Tannic acid is one of the secondary metabolites of plants, which is widely distributed in many plant tissues and plays an important role in plant defense against harmful pests. As a water-soluble natural polyphenol compound, the catechol groups in tannic acid can coordinate with copper ions to form a metal-phenol network, which can be deposited onto the surface of nanomaterials under weak alkaline conditions. In addition, the coordination bonds of metal-phenols can be decomposed under acidic conditions and show pH-responsive properties. More importantly, the complexation process between tannic acid and copper ions is very fast through liquid chemistry and does not contain pollutants or toxic substances, which is a simple and green coating material.

[0004] Pyraclostrobin is one of the urea fungicides and has been widely used to control major plant pathogens in cereals and other crops, including rice sheath blight, wheat powdery mildew, cucumber Fusarium wilt, and tomato gray mold. Common formulations of pyraclostrobin include emulsifiable concentrates, water-dispersible granules, and suspension concentrates. However, the instability of pyraclostrobin in sunlight makes it difficult to control the occurrence and spread of plant diseases in the long term. In addition, the high toxicity of pyraclostrobin to aquatic organisms limits its practical application.

[0005] CN202110185073.2, CN201610788850.1 and CN201010170358.0 describe fungicide compositions or capsules of pyraclostrobin and thiophanate-methyl, but their photostability is basically the same as that of a single agent, they are easily photolyzed, have no controlled-release properties, and have a short half-life; CN201510220325.5 and CN201110191806.X disclose controlled-release granular fertilizers containing pyraclostrobin and thiophanate-methyl, but they have a large particle size and are only suitable for soil application. They have poor leaf adhesion and are easily washed away by rainwater, polluting the environment. They also contain difficult-to-biodegrade materials such as asphalt, paraffin, polyurethane resin, and graphene, which cause severe environmental pollution and are not economical.

[0006] Therefore, it is urgent to develop an intelligent pesticide delivery system with simple process, environmental friendliness, low cost, mild reaction conditions and long-lasting efficacy. Summary of the invention

[0007] In order to solve the deficiencies of the prior art, the purpose of the present invention is to provide a responsive nanopesticide delivery system and its preparation method and application, using copper ions and tannic acid coordination complexes as shell structures to prepare pH-responsive pesticide delivery responsive nanopesticide delivery systems for controlling the release of thiophanate-methyl and pyraclostrobin. The responsive nanopesticide delivery system in this study has significantly improved photostability, rainwater erosion resistance, biological activity and non-target biological safety.

[0008] In order to achieve these purposes and other advantages according to the present invention, a responsive nanopesticide delivery system is provided, wherein the responsive nanopesticide delivery system is a core-shell structure, wherein the core of the core-shell structure is a nanocrystal, and the shell is a metal-phenolic shell layer;

[0009] The nanocrystal is a co-crystal of pyraclostrobin and thiophanate-methyl;

[0010] The metal-phenolic shell layer is a coordination complex of copper ions and tannic acid.

[0011] Preferably, in the nanocrystals, the molar ratio of pyraclostrobin to thiophanate-methyl is 1:(1-2).

[0012] Preferably, the preparation method of the nanocrystals comprises: dispersing pyraclostrobin and thiophanate-methyl in deionized water containing sodium dodecylbenzene sulfonate to form a suspension, then grinding-ultrasonication cycle, and washing with water three times to obtain nanocrystals;

[0013] Preferably, the grinding is carried out in a grinder;

[0014] Preferably, the auxiliary grinding method is to use a solvent for auxiliary grinding, the solvent is water, and the mass ratio of the sum of the mass of pyraclostrobin and thiophanate-methyl to the mass of water is 1:(100-500);

[0015] Preferably, the grinding-ultrasound cycle comprises: grinding the suspension for 15-30 minutes, then stopping the grinding, ultrasonicating for 10-30 minutes, and repeating this process 3-5 times;

[0016] Preferably, in the deionized water containing sodium dodecylbenzene sulfonate, the concentration of sodium dodecylbenzene sulfonate is 0.1-0.5%.

[0017] Preferably, the method for preparing nanocrystals further comprises sequentially washing and solid-liquid separation of the mixture obtained after grinding and ultrasonication;

[0018] Preferably, the cleaning solvent is water, and the number of cleanings is 3-5 times;

[0019] Preferably, the solid-liquid separation method is centrifugation, the centrifugal speed is 10000-12000 rpm, and the centrifugal time is 5-10 min.

[0020] Preferably, using Cu-kα radiation, the X-ray powder diffraction spectrum of the responsive nano pesticide delivery system has sharp new diffraction peaks that are clearly distinguished from pyraclostrobin and thiophanate-methyl.

[0021] The preparation method of the responsive nanopesticide delivery system of the present invention comprises:

[0022] The nanocrystal dispersion is added to the tannic acid solution and vortexed, and then a copper chloride solution and an alkaline buffer solution are added to obtain a responsive nanopesticide delivery system.

[0023] Preferably, the nanocrystal dispersion is obtained by dispersing the nanocrystals in deionized water and shaking;

[0024] Preferably, the mass concentration of nanocrystals in the nanocrystal dispersion is 1-5%;

[0025] Preferably, the vortex time is 10-60s;

[0026] Preferably, the vortex speed is 100-300 rpm.

[0027] Preferably, the solvent of the tannic acid solution is water, and the concentration of the tannic acid solution is 12-24 mM;

[0028] Preferably, the added volume of the tannic acid solution is 0.1-2.4% of the volume of the nanocrystal dispersion;

[0029] Preferably, the copper ion solution comprises a copper chloride solution;

[0030] Preferably, in the copper ion solution, the concentration of copper ions is 12-24 mM;

[0031] Preferably, the added volume of the copper ion solution is 3-5 times the volume of the tannic acid solution.

[0032] Preferably, the alkaline buffer is a MOPS buffer, and the pH of the suspension after adding the MOPS buffer is 7.8-9.2.

[0033] Preferably, the preparation method further comprises sequentially performing solid-liquid separation and washing on the mixed solution obtained by adding tannic acid solution, copper chloride solution and alkaline buffer solution;

[0034] Preferably, the solid-liquid separation method is centrifugation, the centrifugal speed is 10000-12000 rpm, and the centrifugal time is 5-10 min.

[0035] Application of the responsive nanopesticide delivery system of the present invention in the preparation of agricultural fungicides and plant disease control;

[0036] Preferably, the plant comprises corn, citrus, cotton, grape, banana, peanut, soybean, beet, vegetable, sunflower or lawn;

[0037] Preferably, the disease comprises any one of downy mildew, late blight, blight, damping-off, powdery mildew, rust or anthracnose.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. The dual-drug nanocrystals obtained by co-crystallization of pyraclostrobin and thiophanate-methyl have properties that are completely different from the physical mixtures in the prior art, and significantly improve the light and heat stability of pyraclostrobin.

[0040] 2. The responsive nanopesticide delivery system of the present invention has a higher drug loading, better stability, and greatly improved leaf adhesion. In addition, it has a stimulus-responsive release, which can achieve targeted and fixed-point release of fungicides, a long half-life, avoid repeated application of pesticides, reduce environmental pollution, and significantly improve the utilization efficiency of pesticides. The bioavailability is greatly increased, and the bactericidal performance is significantly improved compared to commercially available pesticide compositions, and the biological activity is higher.

[0041] 3. Preparation of the responsive nanopesticide delivery system is a green preparation process. The responsive nanopesticide delivery system can be assembled in water. The process is simple, low-cost, and mild. It can be further developed for large-scale production. Tannic acid and copper ions in the raw materials play an important role in plant defense, are environmentally friendly, and are inexpensive. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is the SEM image of the responsive nanopesticide delivery system;

[0043] Figure 2 is the powder X-ray diffraction pattern of the responsive nanopesticide delivery system;

[0044] Figure 3 is the infrared spectrum of the responsive nanopesticide delivery system;

[0045] Figure 4 are the DSC and TG graphs of the responsive nanopesticide delivery system;

[0046] Figure 5 This is a graph showing the pH responsiveness test results of the responsive nanopesticide delivery system;

[0047] Figure 6 This is a photo-stability test result diagram of the responsive nanopesticide delivery system;

[0048] Figure 7 This is a test result of the rain washability of the responsive nanopesticide delivery system. DETAILED DESCRIPTION

[0049] It should be noted that the following detailed descriptions are all exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those generally understood by those of ordinary skill in the art to which the present invention belongs. The technical scheme of the present invention is further illustrated below by specific embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0050] Example 1

[0051] Pyraclostrobin (PYR)-thiophanate-methyl (TM) nanocrystals (MiniCer, NETZSCH, Germany) were prepared in a ball mill by a mechanochemical method. PYR (0.5 mmol) and TM (1 mmol) were dispersed in 53.6 mL of deionized water containing 0.1% (w / v) sodium dodecylbenzene sulfonate (SDS), and the resulting suspension of 10 zirconia balls with a diameter of 5 mm was added to a stainless steel tank. The suspension was first ground for 20 min, then the grinding was stopped and ultrasonicated for 20 min. The grinding-ultrasonication process was repeated three times. The nanocrystals were washed three times with deionized water and centrifuged at 10,000 rpm for 5 minutes.

[0052] 20 mg of PYR-TM nanocrystals were dispersed in 2 g of deionized water and shaken at 100 rpm for 10 s. Then 20 μL of tannic acid solution (12 mM) was injected into the suspension and vortexed at 100 rpm for 10 s. During the rapid vortexing, 60 μL of copper chloride solution (12 mM) was added. After vortexing at 100 rpm for 10 s, MOPS buffer (0.1 M, pH 8.0) was added to increase the pH to 7.8. The suspension was centrifuged at 10,000 rpm for 5 min and washed with water 3 times to remove excess copper chloride and tannic acid to obtain a responsive nanopesticide delivery system.

[0053] Example 2

[0054] Pyraclostrobin (PYR)-thiophanate-methyl (TM) nanocrystals (MiniCer, NETZSCH, Germany) were prepared in a ball mill by a mechanochemical method. PYR (0.5 mmol) and TM (1 mmol) were dispersed in 160.77 g of deionized water containing 0.3% (w / v) sodium dodecylbenzene sulfonate (SDS), and the resulting suspension of 10 zirconia balls with a diameter of 5 mm was added to a stainless steel tank. The suspension was first ground for 20 min, then the grinding was stopped and ultrasonicated for 20 min. The grinding-ultrasonication process was repeated three times. The nanocrystals were washed with deionized water 4 times and centrifuged at 11,000 rpm for 8 minutes to obtain nanocrystals.

[0055] 20 mg of PYR-TM nanocrystals were dispersed in 0.8 g of deionized water and shaken at 300 rpm for 10 s. Then 24 μL of tannic acid solution (18 mM) was injected into the suspension and vortexed at 300 rpm for 10 s. During the rapid vortexing, 60 μL of copper chloride solution (72 mM) was added. After vortexing at 350 rpm for 30 s, MOPS buffer (0.1 M, pH 8.0) was added to increase the pH to 8.5. The suspension was centrifuged at 11,000 rpm for 8 min and washed with water 4 times to remove excess copper chloride and tannic acid to obtain a responsive nanopesticide delivery system.

[0056] Example 3

[0057] Pyraclostrobin (PYR)-thiophanate-methyl (TM) nanocrystals (MiniCer, NETZSCH, Germany) were prepared in a ball mill by a mechanochemical method. PYR (0.5 mmol) and TM (1 mmol) were dispersed in 267.95 g of deionized water containing 0.5% (w / v) sodium dodecylbenzene sulfonate (SDS), and the resulting suspension of 10 zirconia balls with a diameter of 5 mm was added to a stainless steel tank. The suspension was first ground for 20 min, then the grinding was stopped and ultrasonicated for 20 min. The grinding-ultrasonication process was repeated three times. The nanocrystals were washed with deionized water 5 times and centrifuged at 12,000 rpm for 10 minutes.

[0058] 20 mg of PYR-TM nanocrystals were dispersed in 10 g of deionized water and shaken at 100 rpm for 60 s. Then 500 μL of tannic acid solution (24 mM) was injected into the suspension and vortexed at 300 rpm for 10 s. During the rapid vortexing, 3000 μL of copper chloride solution (24 mM) was added. After vortexing at 300 rpm for 10 s, MOPS buffer (0.1 M, pH 8.0) was added to increase the pH to 9.2. The suspension was centrifuged at 12,000 rpm for 10 min and washed with water 3 times to remove excess copper chloride and tannic acid to obtain a responsive nanopesticide delivery system.

[0059] The obtained responsive nanopesticide delivery system was characterized as follows:

[0060] (1) The microscopic morphology of the responsive nanopesticide delivery system was observed using a scanning electron microscope (G300, Zeiss, Germany). Figure 1 As shown, the responsive nanopesticide delivery system has uniform particle size distribution and regular morphology.

[0061] (2) The powder diffractometer used was D / MAX2500 produced by Rigaku Corporation of Japan. The test conditions were: Cu Kα target test, voltage 40 kV, current 100 mA, scanning wavelength The continuous scanning test was performed at a scanning speed of 8° / min. After the data were collected, Jade 7.0 software was used for data analysis. The powder diffraction spectrum of the responsive nanopesticide delivery system is shown in Figure 2. Figure 2 As shown, it indicates that the responsive nanopesticide delivery system has diffraction peaks that are completely different from those of pyraclostrobin and thiophanate-methyl.

[0062] (3) Fourier transform infrared spectroscopy (FT-IR, Bruker, Germany) was used to detect the functional groups of the samples. Figure 3 As shown in the figure, the FT-IR spectrum of the responsive nanopesticide delivery system shows that after the metal phenolic network film is coated on the surface of the nanocrystal, the -1 A new broad peak appeared in the range of 1400-1600 cm-1, which was caused by the -OH stretching vibration of tannic acid. -1 The vibration bands between correspond to the stretching vibrations of tannic acid aromatic compounds, confirming the successful preparation of the responsive nanopesticide delivery system.

[0063] (4) Tested using Mettler Toledo's DSC 1 / 500 instrument, add about 20 mg of sample into a 40 μL standard aluminum crucible, seal the crucible, and place it in the furnace. High-purity nitrogen is used as protective gas (gas rate of 50 mL / min) and reaction gas (gas rate of 200 mL / min) in the furnace. The measurement temperature range is 25 to 300 °C, and the heating rate is 5 to 10 °C·min-1. The temperature and heat changes of the sample during the heating process are measured, and the results are as follows: Figure 4 As shown, the responsive nanopesticide delivery system has a melting point of 149.2°C, which is significantly higher than 62.4°C of pyraclostrobin and 145.8°C of pyraclostrobin-methyl thiophanate nanocrystals. Therefore, the responsive nanopesticide delivery system has significantly improved thermal stability.

[0064] The obtained responsive nanopesticide intelligent system was characterized as follows:

[0065] (1) pH responsive release performance:

[0066] The pH-responsive release performance of the responsive nanopesticide delivery system was studied using the dialysis bag method. Approximately 2 mL of the responsive nanopesticide delivery system suspension (15 mg / mL) was placed in a dialysis bag immersed in 100 mL of ethanol-citric acid buffer (15:85, v / v; pH 4.0, 5.3, 6.2, 7.9). At regular intervals, 1 mL of the suspension was taken out and filtered through a 0.45 μm filter membrane with the help of a calibration curve for HPLC testing to obtain the release rate under different pH conditions. The results are shown in Figure 2. Figure 5 As shown, the release rates of pyraclostrobin and thiophanate-methyl increased with decreasing pH value, showing good pH response characteristics, indicating that the responsive nanopesticide delivery system prepared by this technology has significant controlled release performance.

[0067] (2) Photostability:

[0068] In order to determine the photostability of the samples, about 50 mg of pyraclostrobin original drug and responsive nanopesticide delivery system were dispersed in water to obtain a suspension. Subsequently, 0.5 mL of each suspension was placed on a Φ10 mm glass slide. After drying, the surface was irradiated with an ultraviolet lamp (36 W, 254 nm, vertical distance 15 cm). The glass slide was removed at regular intervals, washed with methanol and transferred to a centrifuge tube, and the fungicide concentration was determined by high performance liquid chromatography. The results are shown in Figure 2. Figure 6 As shown, the photodegradation half-life of the responsive nanopesticide delivery system is 85 and 76 times that of the mixture of pyraclostrobin and thiophanate-methyl suspension concentrates and the commercial pyraclostrobin suspension concentrate, respectively, with significantly improved photostability.

[0069] (3) Rainwater resistance:

[0070] Using the immersion method, corn leaves were cut into discs and immersed in 200 mg / L pyraclostrobin suspension (PYRSC), a mixture of pyraclostrobin and thiophanate-methyl suspension (PYR-TM), and a responsive nanopesticide delivery system (PYR-TM@TA-Cu) suspension for 15 seconds. After natural drying, the discs were tilted to 30° and washed with 50 ml of deionized water. The extracts were collected and concentrated, re-dissolved with ethanol, and analyzed by high performance liquid chromatography. The results are shown in Figure 2. Figure 7 As shown in the figure, the residual rates of pyraclostrobin suspension (PYR SC), a mixture of pyraclostrobin and thiophanate-methyl suspension (PYR-TM), and a responsive nanopesticide delivery system (PYR-TM@TA-Cu) on corn leaves after leaching with 50 mL of deionized water to simulate rainwater. Under the same conditions, the loss rates of PYR SC, PYR-TM, and PYR-TM@TA-Cu were 32.34%, 48.74%, and 20.12%, respectively, indicating that PYR-TM@TA-Cu significantly improved the persistence of pesticides compared with commercial PYR.

[0071] (4) The control effect of fungicides on spinach leaves:

[0072] Healthy spinach leaves about 5 weeks old were sprayed with PYR-TM@TA-Cu responsive nanopesticide delivery system (300 mg / L, determined by the mass of PYR), PYR SC (300 mg / L) or a mixture of PYR SC and TM SC (PYR 300 mg / L, TM 264.85 mg / L). The treated plants were cultured at 25°C for 16h / 8h day and night. Spinach treated with clean water was used as a control. Leaves were cut off at 0, 3, and 7 days, placed in 90mm discs, and then 5mm Botrytis cinerea discs were inoculated on the back of the leaves. They were incubated in a humid environment at 28°C for 5 days, and the diameter of the infected site was measured. The results showed that after 7 days of spraying, the responsive nanopesticide delivery system still maintained good antibacterial activity, with an antibacterial efficiency of 70.7%, which was significantly higher than the 12% of the commercially available mixture of PYR SC and TM SC, and had significantly improved antibacterial rate and stability.

[0073] Comparative Example 1

[0074] Pyraclostrobin (PYR)-thiophanate-methyl (TM) nanocrystals (MiniCer, NETZSCH, Germany) were prepared in a ball mill by a mechanochemical method. PYR (0.5 mmol) and TM (1 mmol) were dispersed in 160.77 g of deionized water containing 0.3% (w / v) sodium dodecylbenzene sulfonate (SDS), and the resulting suspension of 10 zirconia balls with a diameter of 5 mm was added to a stainless steel tank. The suspension was first ground for 20 min, then the grinding was stopped and ultrasonicated for 20 min. The grinding-ultrasonication process was repeated three times. The nanocrystals were washed with deionized water 4 times and centrifuged at 11,000 rpm for 8 minutes to obtain nanocrystals.

[0075] 20 mg of PYR-TM nanocrystals were dispersed in 0.8 g of deionized water to obtain a nanocrystal suspension without metal-phenolic film. The above test was repeated, and the leaf loss rate on the surface of the rainwater erosion test was 48.74%, which was higher than the 20.12% of the responsive nanopesticide delivery system, indicating that the responsive nanopesticide delivery system has better durability than nanocrystals.

[0076] Comparative Example 2

[0077] Nanocrystals of pyraclostrobin (PYR) and thiophanate-methyl (TM) were prepared by mechanochemical method. 10 mg of PYR nanocrystals and 10 mg of TM nanocrystals were dispersed in 0.8 g of deionized water, shaken at 300 rpm for 10 s, and then 24 μL of tannic acid solution (18 mM) was injected into the suspension and vortexed at 300 rpm for 10 s. During the rapid vortexing, 60 μL of copper chloride solution (72 mM) was added. After vortexing at 350 rpm for 30 s, MOPS buffer (0.1 M, pH 8.0) was added to increase the pH to 8.5. Centrifuged at 11000 rpm for 8 min, washed with water 4 times to remove excess copper chloride and tannic acid, and obtained a drug delivery system of a mixture of pyraclostrobin (PYR) and thiophanate-methyl (TM).

[0078] After testing, under the same photostability test conditions, after 12 hours of illumination, the degradation rate of the drug delivery system of the mixture of pyraclostrobin (PYR) and thiophanate-methyl (TM) was 98.25%, that of the commercial suspension concentrate of pyraclostrobin was 98.98%, and that of the responsive nanopesticide delivery system was 20.45%, proving that the responsive nanopesticide delivery system has better photostability.

[0079] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A responsive nanopesticide delivery system, characterized in that: The responsive nanopesticide delivery system is a core-shell structure, wherein the core of the core-shell structure is a nanocrystal and the shell is a metal-phenolic shell layer; The nanocrystal is a co-crystal of pyraclostrobin and thiophanate-methyl; The metal-phenolic shell is a coordination complex of copper ions and tannic acid; In the nanocrystals, the molar ratio of pyraclostrobin to thiophanate-methyl is 1:(1-2); The preparation method of the nanocrystals comprises: dispersing pyraclostrobin and thiophanate-methyl in deionized water containing sodium dodecylbenzene sulfonate to form a suspension, then grinding and ultrasonication cycle, and washing with water three times to obtain the nanocrystals; The preparation method of the responsive nanopesticide delivery system comprises: The nanocrystal dispersion is added to the tannic acid solution and vortexed, and then a copper chloride solution and an alkaline buffer solution are added to obtain a responsive nanopesticide delivery system.

2. The responsive nanopesticide delivery system according to claim 1, characterized in that: The grinding is carried out in a grinding machine; The grinding is assisted by a solvent, the solvent is water, and the mass ratio of the sum of the mass of pyraclostrobin and thiophanate-methyl to water is 1:(100-500); The grinding-ultrasound cycle includes: grinding the suspension for 15-30 minutes, then stopping the grinding, ultrasonicating for 10-30 minutes, and repeating this process 3-5 times; The concentration of the sodium dodecylbenzene sulfonate in the deionized water is 0.1-0.5%.

3. The responsive nanopesticide delivery system according to claim 2, characterized in that: The method for preparing nanocrystals further comprises sequentially washing and solid-liquid separation of the mixture obtained after grinding and ultrasonication; The cleaning solvent is water, and the number of cleaning times is 3-5 times; The solid-liquid separation method is centrifugation, the centrifugal speed is 10000-12000 rpm, and the centrifugal time is 5-10 min.

4. The responsive nanopesticide delivery system according to claim 1, characterized in that: Using Cu-kα radiation, the X-ray powder diffraction spectrum of the responsive nanopesticide delivery system exhibited sharp new diffraction peaks that were clearly distinguished from pyraclostrobin and thiophanate-methyl.

5. The method for preparing the responsive nanopesticide delivery system according to any one of claims 1 to 4, characterized in that: The preparation method comprises: The nanocrystal dispersion is added to the tannic acid solution and vortexed, and then a copper chloride solution and an alkaline buffer solution are added to obtain a responsive nanopesticide delivery system.

6. The preparation method according to claim 5, characterized in that: The nanocrystal dispersion is obtained by dispersing the nanocrystals in deionized water and shaking; In the nanocrystal dispersion, the mass concentration of nanocrystals is 1-5%; The vortex time is 10-60s; The vortex speed is 100-300 rpm.

7. The preparation method according to claim 5, characterized in that: The solvent of the tannic acid solution is water, and the concentration of the tannic acid solution is 12-24 mM; The added volume of the tannic acid solution is 0.1-2.4% of the volume of the nanocrystal dispersion; In the copper chloride solution, the concentration of copper ions is 12-24 mM; The added volume of the cupric chloride solution is 3-5 times the volume of the tannic acid solution; The alkaline buffer is a MOPS buffer, and the pH of the suspension after adding the MOPS buffer is 7.8-9.

2.

8. The preparation method according to claim 5, characterized in that: The preparation method further comprises sequentially performing solid-liquid separation and washing on a mixed solution obtained by adding a tannic acid solution, a copper chloride solution and an alkaline buffer solution.

9. The preparation method according to claim 8, characterized in that: The solid-liquid separation method is centrifugation, the centrifugal speed is 10000-12000 rpm, and the centrifugal time is 5-10 min.

10. Use of the responsive nanopesticide delivery system according to any one of claims 1 to 4 in the preparation of drugs for preventing and controlling downy mildew, late blight, blight, damping-off, powdery mildew, rust and anthracnose of plants.

11. The use according to claim 10, characterized in that: The plants include corn, citrus, cotton, grapes, bananas, peanuts, soybeans, sugar beets, vegetables, sunflowers or lawns.

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