Nanometer pesticide, its preparation method and application

Abstract

The application provides a kind of nano pesticide and its preparation method and application, the application uses pH response type nanoparticle ZIF-90 as carrier, loads azoxystrobin as drug, to prevent and treat the rice sheath blight caused by rhizoctonia solani. When rhizoctonia solani infects rice, it will produce oxalic acid to cause the pH around the infection area to decrease, so that the ZIF-90 carrier skeleton and hyaluronic acid coating in the application decompose, release azoxystrobin, so as to target inhibit rhizoctonia solani. The application also finds that ZIF-90 and azoxystrobin have synergistic antibacterial activity, which can greatly reduce the EC 50 value of azoxystrobin on rhizoctonia solani, and the encapsulation of ZIF-90 carrier and the end-capping of hyaluronic acid can improve the photolysis stability of azoxystrobin, and also can enhance its adhesion on rice leaves, and the application has important application in agricultural disease control.

Description

Technical Field

[0001] This invention relates to the field of nanopesticide technology, and in particular to a nanopesticide, its preparation method, and its application. Background Technology

[0002] Currently, nanotechnology offers several promising strategies for reducing pesticide use and improving pesticide utilization. Controlled-release systems encapsulate pesticides in nanocarriers, enabling on-demand and site-specific release in response to microenvironments such as pH, temperature, light, glutathione, and enzymes, thus achieving efficient pesticide utilization. Furthermore, this technology can enhance leaf affinity, promote plant growth, and minimize environmental risks.

[0003] Therefore, controlled-release pesticide formulations based on nanocarriers have broad application prospects in agricultural production. Among numerous nanocarrier materials, metal-organic frameworks (MOFs) show great potential in agricultural applications due to their advantages such as high porosity, high loading capacity, easy surface functionalization, and good biocompatibility.

[0004] Generally, naked MOF-based nanopesticides suffer from drawbacks such as easy leakage, poor controlled-release performance, weak adhesion, and poor water dispersibility, which significantly reduce pesticide utilization. Furthermore, the synergistic antifungal effect of nanocarriers and pesticides can improve control efficacy, reduce pesticide dosage, and alleviate pesticide resistance. However, most reported nanopesticide carriers lack antifungal activity or exhibit weak antifungal activity. Azoxystrobin (Azo), as an antifungal agent, has limited its application in field environments due to its high photosynthetic rate and high toxicity to non-target organisms. Summary of the Invention

[0005] This invention provides a nanopesticide, its preparation method, and its application, to address the shortcomings of existing MOF-based nanopesticides, such as easy leakage, poor controlled release performance, weak adhesion, easy photodegradation of azoxystrobin, and high non-target toxicity. It provides a nanopesticide with pH responsiveness, high antibacterial activity, high light stability, and high adhesion.

[0006] In a first aspect, the present invention provides a nanopesticide, the nanopesticide comprising:

[0007] The carrier is ZIF-90 nanoparticles;

[0008] A drug, wherein the drug is encapsulated in the nanocarrier, and the drug has the effect of killing or inhibiting bacteria and / or fungi;

[0009] End-capping agent, which is used to seal the pores of the ZIF-90 nanoparticles.

[0010] Zeolite imidazole ester skeleton-90 (ZIF-90) is a product of Zn 2+ MOF nanoparticles composed of imidazole-2-carboxaldehyde (2-ICA) have advantages such as high loading efficiency, simple preparation, large surface area, and good biocompatibility. ZIF-90 nanoparticles are easily decomposed under acidic conditions, making them suitable for designing pH-responsive pesticide release systems to achieve precise targeted application of active ingredients.

[0011] This invention loads antibacterial drugs onto ZIF-90 nanoparticles and uses a capping agent to seal the pores of ZIF-90, thus developing a pH-responsive nanopesticide. This nanopesticide combines the acidic microenvironment generated during the infection of some pathogens with the acid-sensitive properties of the carrier, thereby constructing an intelligent responsive pesticide controlled-release system.

[0012] Preferably, the drug in the above-mentioned nano-pesticide is azoxystrobin, pyraclostrobin, oxadiazon, azoxystrobin, fluopyram, or fluindazole, with azoxystrobin being the most preferred.

[0013] Azoxystrobin (Azo) is a highly effective, broad-spectrum methoxyacrylate fungicide with good activity against almost all fungal diseases (such as powdery mildew, rust, glume blight, net blotch, downy mildew, and rice blast). However, it is easily decomposed under light and has strong penetrability, which can easily cause leaf aging. Using ZIF-90 granules loaded with Azo can significantly improve its photostability, exhibit pH-responsive release properties, and reduce phytotoxicity.

[0014] Preferably, the capping agent in the above-mentioned nano-pesticide is selected from one or more of hyaluronic acid (HA), chitosan, tannic acid-metal ion complex, pectin, and polydopamine, with hyaluronic acid being the most preferred.

[0015] In addition to encapsulating Azo within ZIF-90 nanoparticles, hyaluronic acid can absorb ultraviolet light, further enhancing the photostability of nanomedicines. The hyaluronic acid coating also improves the wetting properties of nanoparticles on rice leaf surfaces, enhancing adhesion. Furthermore, the hyaluronic acid coating is easily decomposed in acidic environments, and when combined with ZIF-90 nanoparticles, it can effectively release Azo under acidic conditions.

[0016] Preferably, the above-mentioned nano-pesticides are powders, granules, sprays, suspensions, microcapsules, or suspensions.

[0017] Secondly, the present invention provides a method for preparing the above-mentioned nano-pesticide, comprising the following steps:

[0018] (1) The ZIF-90 nanoparticles were resuspended in a methanol solution of azoxystrobin, stirred for 10-14 h, and then washed three times by centrifugation with methanol. The precipitate was then freeze-dried under vacuum for 20-28 h to obtain Azo@ZIF-90 nanoparticles.

[0019] (2) The Azo@ZIF-90 nanoparticles and hyaluronic acid are dissolved in ultrapure water to form Azo@ZIF-90 solution and hyaluronic acid solution, respectively. The hyaluronic acid solution is slowly added to the Azo@ZIF-90 solution under stirring. The mixture is sonicated for 20-25 min, stirred at room temperature for 10-14 h, centrifuged and resuspended in ultrapure water and washed 3 times. The precipitate is then freeze-dried under vacuum for 20-28 h to obtain the final product.

[0020] The ZIF-90 nanoparticles used in the above preparation method can be prepared using any existing technology. For example, in the embodiments of the present invention, the preparation method is as follows:

[0021] (1) Dissolve imidazole-2-carboxaldehyde in N,N-dimethylformamide solution and stir until homogeneous to obtain solution 1. Disperse (CH3COO)2·Zn·2H2O in a mixed solution of N,N-dimethylformamide and ultrapure water in a volume ratio of 3:1 to 1:1 to obtain solution 2.

[0022] (2) Solution 2 was added dropwise to solution 1 under stirring and reacted for 10-20 min. Then, the solution was washed by centrifugation and resuspending with N,N-dimethylformamide, ethanol and ultrapure water respectively. The precipitate was then freeze-dried under vacuum for 20-28 h to obtain the ZIF-90 nanoparticles.

[0023] The ZIF-90 nanoparticles prepared by the above method have a particle size of about 500~700nm.

[0024] Preferably, in the above preparation method, the mass ratio of ZIF-90 nanoparticles to pyraclostrobin in step (3) is 1:2 to 2:1, preferably 1:1.

[0025] Preferably, in the above preparation method, the mass ratio of Azo@ZIF-90 nanoparticles to hyaluronic acid in step (4) is 15:1 to 25:1, preferably 20:1.

[0026] Preferably, the centrifugation speed for centrifugation resuspension in the above preparation method is 8000~12000 rpm, and the centrifugation time is 3~7 min.

[0027] Thirdly, the present invention provides ZIF-90 nanoparticles and / or the above-mentioned nanopesticides in inhibiting Rhizoctonia solani (… Rhizoctonia solani Applications during growth.

[0028] Rhizoctonia solani is a plant pathogenic fungus that releases oxalic acid, creating an acidic environment that allows the release of Azo from the aforementioned nanopesticide. This invention discovers that ZIF-90 nanoparticles themselves also have an inhibitory effect on the growth of Rhizoctonia solani. Loading Azo onto ZIF-90 synergistically enhances the inhibitory effect of Azo on Rhizoctonia solani, thereby reducing its EC50 content. 50 The value decreased from 7.5 mg / L to 0.6 mg / L.

[0029] Fourthly, the present invention provides a method for treating or preventing rice sheath blight, specifically, applying the aforementioned nano-pesticide to rice fields, wherein the rice sheath blight is caused by Rhizoctonia solani.

[0030] The nanopesticide Azo@ZIF-90@HA provided by this invention can protect Azo through ZIF-90 nanoparticle carrier and end-capping agent HA, improving its light resistance. Furthermore, the nanopesticide itself has good adhesion ability, effectively resisting rainwater erosion and increasing the drug's duration of action. In the acidic environment caused by Rhizoctonia solani, the release of Azo effectively inhibits its growth, and its EC50-EC50 effect on Rhizoctonia solani hyphal growth is significant. 50 The value was 2.3 μg / mL, which significantly reduced the diameter of rice sheath blight lesions in the application group.

[0031] The nanopesticide Azo@ZIF-90@HA provided by this invention loads the antifungal drug Azo onto ZIF-90 nanoparticles and blocks them with hyaluronic acid. It exhibits pH-responsive properties and excellent antifungal activity, light resistance, and adhesion. Its drug release rate reaches 100% within 70 hours at pH 5, and it inhibits the EC50 growth of Rhizoctonia solani mycelium. 50 The value was 2.3 μg / mL. After 50 h of irradiation, its photolysis rate was 55.1%, and the photolysis half-life was 1.7 times longer than that of Azo alone. It had a smaller contact angle on the surface of rice leaves, and the residue rate after rainwater washing was 24.4% higher than that of Azo alone. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 This invention provides morphological characterization of Azo@ZIF-90@HA nanoparticles and their intermediate products, wherein... Figure 1The AC values ​​are scanning electron microscope images of ZIF-90, Azo@ZIF-90, and Azo@ZIF-90@HA, respectively. Figure 1 D and E are transmission electron microscopy images of Azo@ZIF-90 and Azo@ZIF-90@HA.

[0034] Figure 2 This invention provides the particle size distribution of Azo@ZIF-90@HA nanoparticles and their intermediate products, wherein... Figure 2 The AC values ​​are the particle size distributions of ZIF-90, Azo@ZIF-90, and Azo@ZIF-90@HA, respectively.

[0035] Figure 3 The results show the release rate curves of the Azo@ZIF-90@HA nanoparticles provided by this invention under different pH conditions.

[0036] Figure 4 The results show the photodegradation resistance of the Azo, Azo@ZIF-90, and Azo@ZIF-90@HA nanoparticles provided by this invention.

[0037] Figure 5 These are the adhesion performance results of Azo SC, Azo@ZIF-90, and Azo@ZIF-90@HA nanoparticles provided by this invention, wherein... Figure 5 A represents the measured blade contact angle. Figure 5 B represents the residual rate against rainwater erosion.

[0038] Figure 6 The results show the inhibition rate of Azo@ZIF-90@HA nanoparticles and their intermediate products on the mycelial growth of Rhizoctonia solani provided by this invention, wherein... Figure 6 A represents the inhibition rate results for Azo, Azo@ZIF-90, and Azo@ZIF-90@HA nanoparticles. Figure 6 B represents the inhibition rate results of ZIF-90@HA, ZIF-90@, and HA.

[0039] Figure 7 This invention provides the results of the inhibition rate of different concentrations of Azo on the mycelial growth of Rhizoctonia solani under the synergistic effect of ZIF-90, wherein... Figure 7 A represents the apparent result. From left to right, the concentrations of Azo in the culture dishes are 0.625, 1.25, 2.5, 5, and 10 mg / L. Figure 7 B represents the statistical result.

[0040] Figure 8 The results show the therapeutic effects of Azo SC, Azo@ZIF-90, and Azo@ZIF-90@HA nanoparticles provided by this invention on rice sheath blight at 5 and 7 days. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0042] Example 1: Synthesis of Azo@ZIF-90@HA

[0043] This embodiment provides the synthesis of Azo@ZIF-90@HA nanoparticles.

[0044] First, ZIF-90 particles are synthesized. The specific steps are as follows:

[0045] (1) Dissolve 961 mg imidazole-2-carboxaldehyde (2-ICA) in 200 mL N,N-dimethylformamide solution and stir magnetically for 15 min at room temperature;

[0046] (2) Disperse 0.55 g (CH3COO)2·Zn·2H2O in 100 mL of a mixed solution of N,N-dimethylformamide and ultrapure water (volume ratio 3:2);

[0047] (3) Then, the (CH3COO)2·Zn·2H2O solution was added dropwise to the imidazole-2-formaldehyde solution under stirring. After stirring magnetically at room temperature for 15 min, the solution was washed by centrifugation and resuspension with N,N-dimethylformamide, ethanol and ultrapure water, respectively. Each time, ultrasonic resuspension was used. Then, the solution was centrifuged at 10,000 rpm for 5 min. Finally, the solution was freeze-dried under vacuum for 24 h to obtain ZIF-90 nanoparticles.

[0048] Then, Azo@ZIF-90 particles were synthesized, and the specific steps are as follows:

[0049] (1) The prepared ZIF-90 nanoparticles (250 mg) were suspended in 20 mg / mL azoxystrobin methanol solution (12.5 mL). After stirring magnetically for 12 h at room temperature, Azo@ZIF-90 solution was obtained. The solution was centrifuged and resuspended in methanol and washed three times. Each time, ultrasonic resuspension was used. Then, the solution was centrifuged at 10000 rpm for 5 min. Finally, Azo@ZIF-90 nanoparticles were obtained by vacuum freeze-drying for 24 h.

[0050] Finally, Azo@ZIF-90@HA particles were synthesized, and the specific steps are as follows:

[0051] (1) Disperse 1 g of Azo@ZIF-90 nanoparticles in 20 mL of ultrapure water, and dissolve 50 mg of hyaluronic acid in 10 mL of ultrapure water;

[0052] (2) Hyaluronic acid solution was slowly added to Azo@ZIF-90 solution under magnetic stirring at room temperature. The mixture was sonicated for 20 min, stirred at room temperature for 12 h, centrifuged and resuspended in ultrapure water for 3 times, and ultrasonic resuspension was used each time. Then it was centrifuged at 10,000 rpm for 5 min, and finally obtained Azo@ZIF-90@HA nanoparticles by vacuum freeze drying for 24 h.

[0053] Example 2 Characterization of Azo@ZIF-90@HA

[0054] This embodiment provides morphological characterization of ZIF-90, Azo@ZIF-90, and Azo@ZIF-90@HA nanoparticles.

[0055] An appropriate amount of sample powder was added to a centrifuge tube containing deionized water to prepare a suspension of 250 μg / mL. Then, the suspension was placed in an ultrasonic homogenizer (500W, 30 minutes) for ultrasonication to ensure that the sample powder was uniformly dispersed in the deionized water.

[0056] A 5 μL drop of sample suspension was pipetted onto a support grid and allowed to air dry at room temperature for 12 hours to immobilize the nanoparticles. The prepared sample was stored in a desiccator to prevent moisture or other contamination. The microstructure of the sample was observed and photographed using scanning and transmission electron microscopy. The results are shown below. Figure 1 As shown in the figure. The particle size distribution of the nanoparticles was analyzed using GraphPad software, and the results are as follows. Figure 2 As shown.

[0057] Depend on Figure 1 It can be seen that both Azo@ZIF-90 and Azo@ZIF-90@HA have good monodispersity and regular cubic crystal morphology. The surface of Azo@ZIF-90 is relatively smooth, while the surface of Azo@ZIF-90@HA, which incorporates hyaluronic acid, is rougher and has obvious protrusions.

[0058] Depend on Figure 2 As can be seen from the particle size distribution calculated using scanning electron microscopy (SEM) images of the samples, the average particle sizes of ZIF-90, Azo@ZIF-90, and Azo@ZIF-90@HA were 642, 780, and 850 nm, respectively. Compared to ZIF-90, the increased particle size of Azo@ZIF-90 and Azo@ZIF-90@HA demonstrates the successful loading of azoxystrobin and the successful encapsulation of hyaluronic acid.

[0059] Example 3: Release performance of Azo@ZIF-90@HA

[0060] This example studies the cumulative release rate of azoxystrobin from Azo@ZIF-90@HA nanoparticles under different pH conditions.

[0061] Azo@ZIF-90@HA nanoparticles were placed in a dialysis bag (MWCO, 3500 Da), which was then placed in phosphate buffer solutions at pH 5, 7, and 9. At specific time intervals, 1 mL of the release solution was removed and the same volume of release solution was added simultaneously to ensure a constant volume of release medium. The cumulative release rate of the sample was calculated using the following formula:

[0062]

[0063] In the formula, Ve is the volume of the solution taken out at time n (1 mL); Cn (mg / L) is the concentration of the sample in the solution taken out at time n; V0 is the total volume of the release medium (200 mL); and mp is the loading mass (mg) of pyraclostrobin in Azo@ZIF-90@HA.

[0064] The samples were analyzed using high-performance liquid chromatography (HPLC). The mobile phase was acetonitrile and 0.1% formic acid aqueous solution (80:20, v / v). The flow rate was 1 mL / min, and the UV detector wavelength was 235 nm. The results are as follows: Figure 3 As shown.

[0065] Depend on Figure 3 It was found that the release rate of Azo@ZIF-90@HA increased with decreasing pH, which is attributed to the decomposition of the ZIF-90 backbone and hyaluronic acid coating under acidic conditions. Compared with neutral (pH 7) and alkaline (pH 9) conditions, the cumulative release rate of Azo@ZIF-90@HA increased by 35.9% and 128.7% respectively after 60 h of treatment in an acidic environment (pH 5). At pH 5, the cumulative release rate of both Azo@ZIF-90 and Azo@ZIF-90@HA reached 100.0% after approximately 70 h, indicating that they have acid-responsive release characteristics and can release the active ingredient on demand when diseases occur, achieving targeted delivery of the active ingredient and thus improving the effective utilization rate of pesticides.

[0066] Example 4: Drug loading rate of Azo@ZIF-90@HA

[0067] This embodiment tested the drug loading rate of Azo@ZIF-90@HA nanoparticles.

[0068] 15 mg of Azo@ZIF-90@HA nanoparticles were placed in a 25 mL volumetric flask, and 200 μL of phosphoric acid was added to dissolve the Azo@ZIF-90@HA nanoparticles. Then, methanol was added to bring the volume to 25 mL, and the mixture was sonicated for 5 min. 1 mL of the final solution was filtered through a 0.22 μm filter into a vial. The azoxystrobin content was determined by high-performance liquid chromatography (HPLC). The mobile phase was acetonitrile and 0.1% formic acid aqueous solution (80:20, v / v). The flow rate was 1 mL / min, and the UV detector wavelength was 235 nm. The experiment was repeated three times. The drug loading rate was calculated using the following formula:

[0069]

[0070] In the formula, C (mg / mL) is the concentration of azoxystrobin, V (25 mL) is the total volume of the final solution, and W (mg) is the precise weight of the nanoparticles. The drug loading rate of Azo@ZIF-90@HA was measured to be 22.2%.

[0071] Example 5: Photolytic stability and adhesion properties of Azo@ZIF-90@HA

[0072] This embodiment tested the photolytic stability of azoxystrobin technical material Azo, Azo@ZIF-90 and Azo@ZIF-90@HA nanoparticles, as well as the adhesion properties of azoxystrobin suspension Azo SC (Nantong Taihe Chemical Co., Ltd., registration certificate number PD20131922), Azo@ZIF-90 and Azo@ZIF-90@HA nanoparticles.

[0073] Photolysis stability: Azoxystrobin technical grade (Azo), Azo@ZIF-90, and Azo@ZIF-90@HA nanoparticle samples were diluted with deionized water to a relative concentration of 100 mg / L for the active ingredient Azo. Then, 200 μL of each diluted solution was evenly spread onto a glass slide (2×4 cm). After water evaporation, the slides were exposed to ultraviolet light with an average irradiance of 25 Mw / cm. At regular intervals, the slides were removed and placed in 50 mL centrifuge tubes, then acetonitrile was added and ultrasonically extracted for 15 min. 5 mL of the extract was transferred to a 10 mL centrifuge tube, 1 g NaCl was added, vortexed for 5 min, centrifuged at 4000 r / min for 5 min, and 1 mL of the supernatant was filtered through a 0.22 μm filter membrane into a vial. The content of azoxystrobin was determined by high-performance liquid chromatography (HPLC). The photolysis residue was calculated as follows:

[0074]

[0075] In the formula, C t Ct represents the concentration of azoxystrobin at time t; C0 represents the initial concentration of azoxystrobin. The measurement results are as follows: Figure 4 As shown.

[0076] Leaf adhesion properties: The dynamic contact angle of nanoparticles on rice leaves was measured using a contact angle meter to evaluate the wettability of Azo@ZIF-90@HA. Rice leaves were washed with ultrapure water and then air-dried on glass slides. Subsequently, 5 μL of each sample solution was dropped onto the surface of the rice leaves, and the contact angle was measured after 0, 15, 45, and 60 s to analyze the wetting process. The results are as follows: Figure 5 As shown in Figure A. Rice leaves were cut into strips and soaked in a 200 mg / L sample dilution for 30 seconds. After natural drying, each leaf was tilted at a 30° angle relative to the ground. To simulate rain washing, 20 mL of deionized water was dropped onto the leaves at a rate of 20 mL / min. The washing liquid was collected, extracted, concentrated, and the content of azoxystrobin was determined by high-performance liquid chromatography. The results are shown in Figure A. Figure 5 As shown in B.

[0077] Depend on Figure 4 It was found that after 50 h of irradiation, the photolysis rates of Azo@ZIF-90 and Azo@ZIF-90@HA were 62.1% and 55.1%, respectively, which were lower than those of Azo (88.7%). Furthermore, Azo@ZIF-90@HA exhibited better UV protection against pesticides than Azo@ZIF-90, which is attributed to the presence of a hyaluronic acid coating on its shell surface, which effectively shields against ultraviolet radiation.

[0078] Depend on Figure 5 As shown in Figure A, compared with Azo SC and Azo@ZIF-90, Azo@ZIF-90@HA has a smaller contact angle on the rice leaf surface. After 60 s, the contact angle of Azo@ZIF-90@HA decreased by 49.6% and 49.7% compared with Azo@ZIF-90 and Azo, respectively, indicating that the introduction of hyaluronic acid enhanced the wetting performance of nanoparticles on the rice leaf surface. This may be due to the good dispersibility of Azo@ZIF-90@HA in aqueous solution, which allows it to be uniformly distributed and diffused on the leaf surface.

[0079] Depend on Figure 5 As shown in section B, the residue rate of Azo@ZIF-90@HA was 24.4% higher than that of Azo SC, indicating that Azo@ZIF-90@HA has better leaf adhesion properties, thus reducing pesticide loss under rainfall conditions. Furthermore, compared to Azo@ZIF-90, the residue rate of Azo@ZIF-90@HA was 48.6% higher, indicating that the introduction of hyaluronic acid can significantly improve the adhesion properties of nanoparticles and enhance their adhesion to the leaf surface.

[0080] Example 6: Inhibitory effect of Azo@ZIF-90@HA on the mycelial growth of Rhizoctonia solani and synergistic activity of the carrier.

[0081] In this embodiment, the inhibitory effects of Azo, Azo@ZIF-90, Azo@ZIF-90@HA, ZIF-90@HA, ZIF-90, and HA on the mycelial growth of Rhizoctonia solani were determined using the mycelial growth rate method. The specific steps are as follows:

[0082] Potato dextrose agar (PDA) media containing Azo at concentrations of 0, 0.625, 1.25, 2.5, 5 and 10 mg / L, Azo@ZIF-90 and Azo@ZIF-90@HA were prepared, as well as PDA media containing 25, 50, 100, 200 and 400 mg / L of ZIF-90, HA and ZIF-90@HA, respectively.

[0083] Rhizoctonia solani (the Rhizoctonia solani used for preparing the mycelial cakes was provided by the Institute of Plant Protection, Chinese Academy of Agricultural Sciences) was cultured in 9 cm diameter Petri dishes (PDA solid medium) for 48 h. Mycelial cakes with a diameter of 5 mm were then punched from the edge of the medium using a puncher. The mycelial cakes were placed in the center of each group of PDA medium, with three replicates used for each experiment. All Petri dishes were incubated at 25℃ for 48 h. The colony diameter was measured using the cross-crossing method, and the antibacterial activity was calculated using the following formula. The results are shown below. Figure 6 As shown.

[0084]

[0085] PDA media with Azo concentrations of 0, 0.625, 1.25, 2.5, 5, and 10 mg / L were prepared, as well as the above-mentioned Azo-containing PDA media with ZIF-90 added to a final concentration of 100 mg / L. The above antibacterial experiments were then repeated to evaluate the synergistic inhibitory effect of ZIF-90 and Azo against Rhizoctonia solani. The results are as follows: Figure 7 As shown.

[0086] Depend on Figure 6 As shown in A, treatment with Azo, Azo@ZIF-90, and Azo@ZIF-90@HA for 48 h resulted in an EC50 response against Rhizoctonia solani. 50 The values ​​were 4.0, 2.8, and 2.3 mg / L, respectively. Compared with Azo, Azo@ZIF-90 and Azo@ZIF-90@HA showed better EC50 response against Rhizoctonia solani. 50 The values ​​decreased by 30.7% and 41.2% respectively, indicating that the antibacterial ability of azoxystrobin was improved after being loaded onto a nanocarrier. Figure 6As shown in B, the nanocarriers ZIF-90 and ZIF-90@HA also exhibited antibacterial activity against Rhizoctonia solani, with EC50 increasing after 48 h of treatment. 50 The values ​​were 82.3 mg / L and 86.6 mg / L, respectively. Hyaluronic acid also exhibited extremely low antibacterial activity against Rhizoctonia solani, but its EC50 values ​​were high. 50 The value is greater than 600 mg / L.

[0087] Depend on Figure 7 It can be seen that after 72 h of treatment, Azo treatment alone reduced the EC of Rhizoctonia solani. 50 The value was 7.5 mg / L, while the addition of 100 mg / L ZIF-90 to Azo solutions of various concentrations reduced the EC50 of Rhizoctonia solani. 50 The value dropped to 0.6 mg / L, and its EC 50 The value was reduced by about 11.0 times compared to the Azo treatment alone, indicating that ZIF-90 and pyraclostrobin have synergistic antibacterial activity, which can improve the bioactivity against Rhizoctonia solani and thus play a synergistic role.

[0088] Example 7: Therapeutic activity of Azo@ZIF-90@HA against rice sheath blight

[0089] This embodiment uses in vitro rice leaf inoculation to evaluate the control effect of Azo@ZIF-90@HA nanoparticles on rice sheath blight.

[0090] Rice was potted in a greenhouse (25℃ / 20℃, day / night temperature, supplemental lighting from 8:00 to 18:00, 70% relative humidity). After about two months of growth, fresh rice leaves were cut, rinsed with sterile water, and placed on the surface of water agar medium. AzoSC, Azo@ZIF-90, and Azo@ZIF-90@HA were diluted with 0.1% Tween-80 aqueous solution to ensure that the concentration of the active ingredient was 200 mg / L. Rhizoctonia solani was inoculated onto rice leaves. 48 h after inoculation, the sample solution was sprayed evenly onto the rice leaves to study its therapeutic activity against Rhizoctonia solani. The plants were cultured in a constant temperature and light incubator (25℃, 12 / 12 h: light / dark, 75% humidity). The diameter of lesions was measured in two vertical directions after 5 and 7 days of culture. Sterile water served as a blank control group. Each treatment used 15 rice leaves, and each treatment was repeated 5 times. The control effect was calculated as follows:

[0091]

[0092] In the formula, D and d are the lesion diameters of the control group and the treatment group, respectively, and the results are as follows: Figure 8 As shown.

[0093] Depend on Figure 8It was found that after 5 and 7 days of treatment, the therapeutic activity of Azo@ZIF-90@HA against rice sheath blight was significantly higher than that of Azo SC and Azo@ZIF-90. On day 7, the control effect of Azo@ZIF-90@HA against rice sheath blight was 195.4% and 68.6% higher than that of Azo SC and Azo@ZIF-90, respectively, indicating that Azo@ZIF-90@HA has a better sustained control effect against rice sheath blight, thus prolonging the effective period of azoxystrobin.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A nano-pesticide, characterized in that, The nanopesticides include: The carrier is ZIF-90 nanoparticles; Azoxystrobin, wherein the azoxystrobin is encapsulated in the carrier; End-capping agent, which is used to seal the pores of the ZIF-90 nanoparticles, wherein the end-capping agent is hyaluronic acid.

2. The nanopesticide according to claim 1, characterized in that, It is available in powder, granule, spray, microcapsule, and suspension formulations.

3. The method for preparing the nano-pesticide according to claim 1 or 2, characterized in that, Includes the following steps: (1) ZIF-90 nanoparticles were resuspended in a methanol solution of azoxystrobin and stirred for 10-14 h. After centrifugation and washing three times with methanol, the precipitate was freeze-dried under vacuum for 20-28 h to obtain Azo@ZIF-90 nanoparticles. (2) The Azo@ZIF-90 nanoparticles and hyaluronic acid are dissolved in ultrapure water to form Azo@ZIF-90 solution and hyaluronic acid solution, respectively. The hyaluronic acid solution is slowly added to the Azo@ZIF-90 solution under stirring. The mixture is sonicated for 20-25 min, stirred at room temperature for 10-14 h, centrifuged and resuspended in ultrapure water and washed 3 times. The precipitate is then freeze-dried under vacuum for 20-28 h to obtain the final product.

4. The preparation method according to claim 3, characterized in that, The mass ratio of ZIF-90 nanoparticles to pyraclostrobin in step (3) is 1:2 to 2:

1.

5. The preparation method according to claim 4, characterized in that, The mass ratio of ZIF-90 nanoparticles to pyraclostrobin in step (3) is 1:

1.

6. The preparation method according to claim 3, characterized in that, In step (4), the mass ratio of the Azo@ZIF-90 nanoparticles to the hyaluronic acid is 15:1 to 25:

1.

7. The preparation method according to claim 6, characterized in that, In step (4), the mass ratio of the Azo@ZIF-90 nanoparticles to the hyaluronic acid is 20:

1.

8. The preparation method according to any one of claims 3-7, characterized in that, The centrifugation speed for centrifugation resuspension is 8000~12000 rpm, and the centrifugation time is 3~7 min.

9. The application of ZIF-90 nanoparticles and / or the nanopesticides according to claim 1 or 2 in inhibiting the growth of Rhizoctonia solani.

10. A method for treating or preventing rice sheath blight, characterized in that, The nano-pesticide described in claim 1 or 2 is applied to rice fields, wherein the rice sheath blight is caused by Rhizoctonia solani.

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