A nanofluazinam sustained-release agent and its preparation method and application

Abstract

The present invention belongs to the technical field of pesticides, and specifically relates to a nano fluazinam sustained-release agent and a preparation method and application thereof. The nano fluazinam sustained-release agent provided by the present invention comprises a sustained-release capsule dispersed in water, wherein the sustained-release capsule is a core-shell structure, the core of the core-shell structure is fluazinam original drug, and the shell of the core-shell structure is a carrier and a surfactant; the carrier material is ethyl cellulose or polylactic acid; the surfactant comprises one or more of maleic rosin polyoxypropylene oxyethylene ether sulfonate, maleic rosin octylphenol polyoxyethylene ether diester acid sodium salt, polyvinyl alcohol, polyoxyethylene ether, polyoxyethylene alcohol, polyurethane, polyethylene glycol, polyvinyl alcohol, polyvinyl ether and polyvinyl amide. The surfactant and the carrier are combined together by intermolecular forces or cross-entanglement between molecular chains, which can reduce the surface tension of the fluazinam sustained-release agent while reducing the release rate of fluazinam, so as to prolong the effective period and improve the utilization rate of the agent.

Description

Technical Field

[0001] The invention belongs to the technical field of pesticides, and specifically relates to a nano fluazinam sustained-release agent and a preparation method and application thereof. Background Art

[0002] Clubroot is considered one of the most destructive soil diseases. It causes serious damage to many cruciferous plants, such as rapeseed, kale and cabbage. Clubroot infection is the direct cause of clubroot. Clubroot has a complex life cycle. Primary infection does not cause visible symptoms to the plant. After secondary infection, secondary parasites occur in the root cortex, causing obvious deformities of the plant root system. Each secondary parasite will eventually divide in the deformed root to produce a large number of dormant spores, which enter the soil when the root tissue decomposes, completing the cycle of the pathogen. It can survive in the soil for up to 20 years, seriously affecting the cruciferous plant planting industry.

[0003] Fluazifop is a protective fungicide with broad-spectrum activity, belonging to the dinitroaniline fungicide class. Its inhibitory effect is based on the uncoupling of oxidative phosphorylation of fungal pathogens to cut off the fungus's energy-generating system, and has high fungicidal activity. Fluazifop has a relatively ideal prevention and control effect on soil diseases including cabbage clubroot and peanut root rot, and is currently a promoted agent for the prevention and control of soil diseases. Unlike fungicides with site-specific modes, the action of fluazifop is non-specific, so the possibility of screening out drug-resistant strains is small. However, the existing fluazifop has a short duration of effect as an agent for the treatment of clubroot and a low utilization rate. Summary of the invention

[0004] In view of this, the present invention provides a nano fluazinam sustained-release agent and a preparation method and application thereof. The nano fluazinam sustained-release agent provided by the present invention has a sustained-release property, prolongs the lasting effect while maintaining the efficacy, and improves the utilization rate of the agent.

[0005] In order to solve the above technical problems, the present invention provides a nano fluazinam sustained-release agent, including a sustained-release capsule dispersed in water, wherein the sustained-release capsule is a core-shell structure, the core of the core-shell structure is the fluazinam original drug, and the shell of the core-shell structure is a carrier and a surfactant; the carrier material is ethyl cellulose or polylactic acid; the surfactant includes one or more of maleic rosin polyoxypropylene oxyethylene ether sulfonate, maleic rosin octylphenol polyoxyethylene ether diester acid sodium salt, polyoxyethylene ether, polyoxyethylene alcohol, polyurethane, polyethylene glycol, polyvinyl alcohol, polyvinyl ether and polyvinyl amide.

[0006] Preferably, the mass percentage of the fluazinam original drug in the fluazinam sustained-release agent is 0.8-30%.

[0007] Preferably, the mass ratio of the carrier to the surfactant is 3:1.8-2.2.

[0008] Preferably, the fluazinam sustained-release agent is in the form of spherical particles, and the average particle size of the fluazinam sustained-release agent is 200 to 300 nm.

[0009] The present invention also provides a method for preparing the fluazinam sustained-release agent described in the above technical solution, comprising the following steps:

[0010] The fluazinam original drug, the carrier and the organic solvent are first mixed to obtain an oil phase;

[0011] secondly mixing the surfactant and water to obtain an aqueous phase;

[0012] The oil phase is added into the water phase for emulsification and then the organic solvent is removed to obtain the fluazinam sustained-release agent.

[0013] Preferably, the organic solvent comprises dichloromethane;

[0014] The mass ratio of the fluazinam original drug to the carrier is 0.8 to 10:3;

[0015] The volume ratio of the mass of the fluazinam original drug to the organic solvent is 0.8-30 g:30-100 mL;

[0016] The mass ratio of the surfactant to water is 1 to 3:50.

[0017] Preferably, the volume ratio of the oil phase to the water phase is 3 to 10:10.

[0018] Preferably, the emulsification is carried out under ultrasonic conditions, the power of the ultrasound is 500-600W, and the time of the ultrasound is 10-20 minutes.

[0019] Preferably, the removal of the organic solvent is carried out under stirring, the stirring speed is 500 to 620 r / min, and the stirring time is 18 to 24 h.

[0020] The present invention also provides the use of the fluazinam sustained-release agent described in the above technical solution or the fluazinam sustained-release agent prepared by the preparation method described in the above technical solution in preventing and treating clubroot.

[0021] The present invention provides a nano fluazinam sustained-release agent, comprising a sustained-release capsule dispersed in water, wherein the sustained-release capsule is a core-shell structure, wherein the core of the core-shell structure is fluazinam original drug, and the shell of the core-shell structure is a carrier and a surfactant; the carrier material is ethyl cellulose or polylactic acid; the surfactant comprises one or more of maleic rosin polyoxypropylene oxyethylene ether sulfonate, maleic rosin octylphenol polyoxyethylene ether diester acid sodium salt, polyoxyethylene ether, polyoxyethylene alcohol, polyurethane, polyethylene glycol, polyvinyl alcohol, polyvinyl ether and polyvinyl amide. In the present invention, the surfactant and the carrier are combined together by intermolecular forces or cross-entanglement between molecular chains, and the surface tension of the fluazinam sustained-release agent can be reduced while reducing the release rate of fluazinam, which is beneficial for the fluazinam sustained-release agent to be better retained on the surface of plant leaves or dispersed in the soil, so as to prolong the lasting period and improve the utilization rate of the agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a comparison chart of the particle size and PDI of the sustained-release preparations prepared in Examples 3 and 8 and Comparative Examples 1 to 4;

[0023] Figure 2 A comparison chart of the particle size and PDI of the sustained-release preparations prepared in Examples 11 to 15;

[0024] Figure 3 are SEM images of the sustained-release agents prepared in Examples 11 to 15, wherein a is the SEM image of Example 12, b is the SEM image of Example 13, c is the SEM image of Example 14, d is the SEM image of Example 15, and e is the SEM image of Example 11;

[0025] Figure 4 This is a TEM image of the fluazinam sustained-release preparation prepared in Example 11;

[0026] Figure 5 This is a SEM image of the fluazinam sustained-release preparation prepared in Example 11;

[0027] Figure 6 This is a comparison curve of the cumulative release between Example 11 and the commercially available fluazinam suspension;

[0028] Figure 7 This is a comparison chart of the particle size and PDI of the fluazinam sustained-release preparation prepared in Example 11 under different storage conditions, wherein a is a comparison chart of the results stored at 0±2°C, b is a comparison chart of the results stored at 25±2°C, and c is a comparison chart of the results stored at 54±2°C;

[0029] Figure 8The figures are actual pictures of the cultivated Chinese cabbage 45 days after the application of the medicine, wherein a and b are actual pictures of the Chinese cabbage applied with the fluazinam sustained-release suspension of Example 11 at a mass concentration of 100 mg / L, c and d are actual pictures of the Chinese cabbage applied with the fluazinam sustained-release suspension of Example 11 at a mass concentration of 50 mg / L, and e and f are actual pictures of the Chinese cabbage treated with clean water. DETAILED DESCRIPTION

[0030] The present invention provides a nano fluazinam sustained-release agent, comprising a sustained-release capsule dispersed in water, wherein the sustained-release capsule is a core-shell structure, wherein the core of the core-shell structure is fluazinam original drug, and the shell of the core-shell structure is a carrier and a surfactant. In the present invention, the carrier material is ethyl cellulose or polylactic acid; the surfactant comprises one or more of maleic rosin polyoxypropylene oxyethylene ether sulfonate, maleic rosin octylphenol polyoxyethylene ether diester acid sodium salt, polyoxyethylene ether, polyoxyethylene alcohol, polyurethane, polyethylene glycol, polyvinyl alcohol, polyvinyl ether and polyvinyl amide, preferably two of maleic rosin polyoxypropylene oxyethylene ether sulfonate (MRES), maleic rosin octylphenol polyoxyethylene ether diester acid sodium salt, polyoxyethylene ether, polyoxyethylene alcohol, polyurethane, polyethylene glycol, polyvinyl alcohol (PVA), polyvinyl ether and polyvinyl amide. In the present invention, when the surfactant includes two or more of the above-mentioned specific substances, the first specific substance is maleic rosin polyoxypropylene oxyethylene ether sulfonate or maleic rosin octylphenol polyoxyethylene ether diester acid sodium salt, and the second specific substance is polyoxyethylene ether, polyoxyethylene alcohol, polyurethane, polyethylene glycol, polyvinyl alcohol, polyvinyl ether or polyvinyl amide. The mass ratio of the first specific substance to the second specific substance is preferably 3:1 to 9, more preferably 3:3 to 6.

[0031] In the present invention, the mass ratio of the carrier to the surfactant is preferably 3:1.8-2.2, more preferably 3:2.

[0032] In the present invention, the mass percentage of the fluazinam original drug in the fluazinam sustained-release agent is preferably 0.8-30%, more preferably 2-10%. In the present invention, the mass concentration of the fluazinam original drug is preferably above 90%, more preferably 95-98%.

[0033] In the present invention, the fluazinam sustained-release agent is preferably spherical particles, and the average particle size of the fluazinam sustained-release agent is preferably 200 to 300 nm, more preferably 200 to 250 nm.

[0034] The fluazinam sustained-release agent provided by the present invention has a longer sustained-release performance, which is beneficial to prolonging the lasting effect while maintaining the efficacy, and is beneficial to reducing the number of soil application of the drug, which meets the expectations of the soil application method.

[0035] The present invention also provides a method for preparing the fluazinam sustained-release agent described in the above technical solution, comprising the following steps:

[0036] The fluazinam original drug, the carrier and the organic solvent are first mixed to obtain an oil phase;

[0037] secondly mixing the surfactant and water to obtain an aqueous phase;

[0038] The oil phase is added into the water phase for emulsification and then the organic solvent is removed to obtain the fluazinam sustained-release agent.

[0039] In the present invention, the fluazinam original drug, a carrier and an organic solvent are first mixed to obtain an oil phase. In the present invention, the organic solvent preferably includes dichloromethane.

[0040] In the present invention, the mass ratio of the fluazinam technical and the carrier is preferably 0.8-10:3, more preferably 2-8:3. In the present invention, the mass ratio of the fluazinam technical and the volume ratio of the organic solvent is preferably 0.8-30 g:30-100 mL, more preferably 0.8-3 g:30-40 mL.

[0041] In the present invention, the first mixing is preferably carried out under stirring conditions, and the stirring is preferably magnetic stirring. The present invention has no special requirements on the speed and time of the stirring, as long as the stirring can be uniform. In the present invention, the oil phase system is uniform and free of impurities.

[0042] The present invention secondly mixes the surfactant and water to obtain an aqueous phase. In the present invention, the water is preferably deionized water. In the present invention, the mass ratio of the surfactant to water is preferably 1 to 3:50, more preferably 1 to 1.1:50.

[0043] In the present invention, the second mixing is preferably carried out under stirring conditions, and the stirring is preferably magnetic stirring. The present invention has no special requirements on the speed and time of the stirring, as long as it can be mixed evenly. In the present invention, the aqueous phase system is uniform and free of impurities.

[0044] After obtaining the oil phase and the water phase, the present invention adds the oil phase to the water phase for emulsification and then removes the organic solvent to obtain the fluazinam sustained-release agent. In the present invention, the volume ratio of the oil phase to the water phase is preferably 3 to 10:10, more preferably 3 to 4:10. In the present invention, the oil phase is preferably added to the water phase during the emulsification process. In the present invention, the addition rate of the oil phase to the water phase is preferably dropwise addition.

[0045] In the present invention, the emulsification is preferably carried out under ultrasonic conditions, the power of the ultrasound is preferably 500-600W, more preferably 550-600W; the time of the ultrasound is preferably 10-20min, more preferably 15-20min. In the present invention, the ultrasound is preferably interval ultrasound, specifically the ultrasound time includes the working time and the intermittent time of the cycle in sequence, the working time in each cycle is preferably 2min, and the intermittent time in each cycle is preferably 2min.

[0046] In the present invention, the emulsification is preferably carried out in an ultrasonic cell disruptor.

[0047] In the present invention, the organic solvent is preferably removed under stirring, the stirring speed is preferably 500-620 r / min, more preferably 550-580 r / min; the stirring time is preferably 18-24 h, more preferably 20-22 h. In the present invention, the organic solvent is volatilized during the stirring process.

[0048] The present invention also provides the use of the fluazinam sustained-release agent described in the above technical solution or the fluazinam sustained-release agent prepared by the preparation method described in the above technical solution in preventing and treating clubroot. The present invention has no special limitation on the application method, and the conventional method in the art can be used.

[0049] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0050] Sources of materials and instruments in the embodiments: fluazinam technical (>98%), Jiangsu Suli Fine Chemical Co., Ltd.; Nongru 600 and Nongru 700, Beijing Jinyue Biotechnology Co., Ltd.; castor oil polyoxyethylene ether EL-40, Hai'an Petrochemical Plant, Jiangsu Province; polycarboxylates, Shijiazhuang Kaifa Chemical Pharmaceutical Co., Ltd.; polyvinyl alcohol, Beijing Feimo Biotechnology Co., Ltd.; maleic rosin polyoxypropylene oxyethylene ether sulfonate, Jiangsu Qingyu Chemical Technology Co., Ltd.; ethyl cellulose, Sigma-Aldrich (Shanghai) Trading Co., Ltd.; dichloromethane, Beijing Zhongchuang Hongda Technology Co., Ltd.; 50% fluazinam suspension, Japan Ishihara Industry Co., Ltd.; 500g / L fluazinam suspension, Zhejiang Tianfeng Bioscience Co., Ltd.; deionized water was prepared by Elix Essential 5 pure water machine (15.0MΩ·cm, TOC≤4ppb); dialysis bag MD34 (8000D), Beijing Runzekang Biotechnology Co., Ltd.; silicon wafer, Beijing Huike Tongchuang Scientific Instrument Co., Ltd.; copper mesh, Wuhan Prolog Technology Co., Ltd.

[0051] Ultrasonic cell disruptor (JY92-IIN, Ningbo Xinzhi Biotechnology Co., Ltd.); magnetic stirrer (RCH-3, Tokyo Rikkigi Co., Ltd., Japan); analytical balance (ME204E, Mettler-Toledo International Trading (Shanghai) Co., Ltd.); ultrasonic cleaner (SB5200DT, Ningbo Xinzhi Biotechnology Co., Ltd.); cantilever stirrer (EUROSTAR 60, IKA Instrument Equipment Co., Ltd.); high-speed refrigerated centrifuge (ST16R, Thermo Fisher Scientific Inc., USA); transmission electron microscope (HT7700, Hitachi, Tokyo Hitachi Co., Ltd.); scanning electron microscope (SU-8010, Tokyo Hitachi Co., Ltd.); precision balance (ME204E, Mettler-Toledo International Trading (Shanghai) Co., Ltd.); vacuum coater (ETD-800, Beijing Yilibotong Technology Development Co., Ltd.).

[0052] Example 1

[0053] 3.25 g of fluazinam original drug, 3 g of polylactic acid and 40 mL of dichloromethane were mixed under magnetic stirring to obtain an oil phase;

[0054] 2 g of maleic rosin octylphenol polyoxyethylene ether sodium ester and 100 g of deionized water were mixed under magnetic stirring to obtain an aqueous phase;

[0055] The aqueous phase was placed in an ultrasonic cell disruptor, and the oil phase was added dropwise to the aqueous phase under ultrasonic conditions (ultrasonic power of 580 W, cyclic operation and intermittence, working time of 2 min and intermittent time of 2 min), and then emulsified for 15 min, and stirred for 20 h at a speed of 600 r / min to remove dichloromethane to obtain a fluazinam sustained-release agent.

[0056] Example 2

[0057] The fluazinam sustained-release preparation was prepared according to the method of Example 1, except that polylactic acid was replaced by ethyl cellulose.

[0058] Example 3

[0059] The fluazinam sustained-release agent was prepared according to the method of Example 1, except that the maleic rosin octylphenol polyoxyethylene ether diester acid sodium salt was replaced by maleic rosin polyoxypropylene oxyethylene ether sulfonate.

[0060] Example 4

[0061] The fluazinam sustained-release agent was prepared according to the method of Example 1, except that the sodium salt of maleic rosin octylphenol polyoxyethylene ether diester acid was replaced by polyoxyethylene ether.

[0062] Example 5

[0063] The fluazinam sustained-release agent was prepared according to the method of Example 1, except that the sodium salt of maleic rosin octylphenol polyoxyethylene ether diester acid was replaced by polyoxyethylene alcohol.

[0064] Example 6

[0065] The fluazinam sustained-release agent was prepared according to the method of Example 1, except that the sodium salt of maleic rosin octylphenol polyoxyethylene ether diester acid was replaced by polyurethane.

[0066] Example 7

[0067] The fluazinam sustained-release preparation was prepared according to the method of Example 1, except that the sodium salt of maleic rosin octylphenol polyoxyethylene ether diester acid was replaced by polyethylene glycol.

[0068] Example 8

[0069] The fluazinam sustained-release agent was prepared according to the method of Example 1, except that the sodium salt of maleic rosin octylphenol polyoxyethylene ether diester acid was replaced by polyvinyl alcohol.

[0070] Example 9

[0071] The fluazinam sustained-release agent was prepared according to the method of Example 1, except that the sodium salt of maleic rosin octylphenol polyoxyethylene ether diester acid was replaced by polyethylene ether.

[0072] Example 10

[0073] The fluazinam sustained-release agent was prepared according to the method of Example 1, except that the sodium salt of maleic rosin octylphenol polyoxyethylene ether diester acid was replaced by polyvinyl amide.

[0074] Embodiment 11

[0075] The fluazinam sustained-release agent was prepared according to the method of Example 1, except that the maleic rosin octylphenol polyoxyethylene ether sodium diester was replaced by a mixture of polyvinyl alcohol and maleic rosin polyoxypropylene oxyethylene ether sulfonate in a mass ratio of 2:1.

[0076] Example 12

[0077] The fluazinam sustained-release agent was prepared according to the method of Example 1, except that the maleic rosin octylphenol polyoxyethylene ether sodium diester was replaced by a mixture of polyvinyl alcohol and maleic rosin polyoxypropylene oxyethylene ether sulfonate in a mass ratio of 3:1.

[0078] Embodiment 13

[0079] The fluazinam sustained-release agent was prepared according to the method of Example 1, except that the maleic rosin octylphenol polyoxyethylene ether sodium diester was replaced by a mixture of polyvinyl alcohol and maleic rosin polyoxypropylene oxyethylene ether sulfonate in a mass ratio of 1:1.

[0080] Embodiment 14

[0081] The fluazinam sustained-release agent was prepared according to the method of Example 1, except that the maleic rosin octylphenol polyoxyethylene ether sodium diester was replaced by a mixture of polyvinyl alcohol and maleic rosin polyoxypropylene oxyethylene ether sulfonate in a mass ratio of 1:2.

[0082] Embodiment 15

[0083] The fluazinam sustained-release agent was prepared according to the method of Example 1, except that the maleic rosin octylphenol polyoxyethylene ether sodium diester was replaced by a mixture of polyvinyl alcohol and maleic rosin polyoxypropylene oxyethylene ether sulfonate in a mass ratio of 1:3.

[0084] Comparative Example 1

[0085] The fluazinam sustained-release agent was prepared according to the method of Example 1, except that maleic rosin octylphenol polyoxyethylene ether diester acid was replaced by Nongru 600.

[0086] Comparative Example 2

[0087] The fluazinam sustained-release agent was prepared according to the method of Example 1, except that maleic rosin octylphenol polyoxyethylene ether diester acid was replaced by Nongru 700.

[0088] Comparative Example 3

[0089] The fluazinam sustained-release agent was prepared according to the method of Example 1, except that the maleic rosin octylphenol polyoxyethylene ether diester acid was replaced by castor oil polyoxyethylene ether EL-40.

[0090] Comparative Example 4

[0091] The fluazinam sustained-release agent was prepared according to the method of Example 1, except that the maleic rosin octylphenol polyoxyethylene ether diester acid was replaced by polycarboxylate.

[0092] EXCEL 2019 and IBM SPSS Statistics 25 were used to analyze and process the experimental data, and some test results were expressed as "mean ± standard deviation". Origin 2018 was used to process the experimental data and convert the data into intuitive images including bar charts and line charts. In the process of processing the indoor efficacy data, the DMRT method was used to analyze the significance of the difference.

[0093] Characterization of systems prepared with different ratios of PVA and MRES:

[0094] PVA is a non-ionic surfactant with high surface activity and can be used together with other ionic surfactants. MRES is an ionic surfactant that can effectively inhibit particle agglomeration and maintain the stability of the system. The particle size and PDI of the sustained-release agents prepared in Examples 3, 8 and Comparative Examples 1 to 4 were measured using a laser particle size analyzer, and a comparison chart of the particle size and PDI of the sustained-release agents prepared in Examples 3, 8 and Comparative Examples 1 to 4 was drawn, as shown in FIG. Figure 1 shown.

[0095] Depend on Figure 1 It can be seen that the average particle size and PDI of the sustained-release preparations prepared in Examples 3 and 8 are both in a good state, with the average particle size being between 200 and 230 nm and the PDI value being less than 0.3.

[0096] The particle size and PDI of the sustained-release agents prepared in Examples 11 to 15 were measured using a laser particle size analyzer, and a comparison chart of the particle size and PDI of the sustained-release agents prepared in Examples 11 to 15 was drawn, as shown in FIG. Figure 2 shown.

[0097] Depend on Figure 2 It can be seen that the average particle size and PDI of the sustained-release preparations prepared in Examples 11 to 15 are in a good state, with an average particle size of 200 to 300 nm, and a PDI value of less than 0.3, and the differences between them are not obvious.

[0098] The morphological characteristics of the sustained-release agents prepared in Examples 11 to 15 were observed using a scanning electron microscope, and SEM images were obtained. Figure 3 As shown, a is the SEM image of Example 12, b is the SEM image of Example 13, c is the SEM image of Example 14, d is the SEM image of Example 15, and e is the SEM image of Example 11. Figure 3 It can be seen that the fluazinam sustained-release preparations prepared in Examples 11 to 15 also present smooth spheres of uniform size and good dispersibility, and are in a good state.

[0099] Morphological characterization of fluazinam sustained-release preparation:

[0100] The morphology was observed using a transmission electron microscope: The solid fluazinam nano sustained-release agent prepared in Example 11 obtained by centrifugation during the determination of the particle size and dispersibility of the fluazinam sustained-release agent was diluted with deionized water to a concentration of about 0.005% (w / w). The diluted solution was placed under ultrasonic conditions and oscillated to dissolve until it was evenly dispersed. 4 μL of the solution was added dropwise to a 300-mesh carbon film copper grid and spread evenly, and then left at room temperature. After the sample droplets dried naturally, they were placed in a transmission electron microscope, and the morphology of the fluazinam nano sustained-release agent was observed under an accelerating voltage of 80 kV to obtain a TEM image, as shown in FIG. Figure 4As shown, c and d are TEM images of different regions of the fluazinam nano sustained-release agent.

[0101] The morphology was observed using a scanning electron microscope: the solid fluazinam nano sustained-release agent prepared in Example 11 obtained by centrifugation during the determination of the particle size and dispersibility of the fluazinam sustained-release agent was diluted with deionized water to a concentration of about 0.05% (w / w). The diluted solution was placed under ultrasonic conditions and oscillated to dissolve until it was evenly dispersed. 8 μL of the solution was added dropwise to the smooth surface of the silicon wafer and spread evenly, and then left at room temperature. After the sample droplets dried naturally, the silicon wafer containing the drug was placed in a high vacuum coating instrument to coat the sample surface with a layer of metal film. Finally, the silicon wafer was placed in a scanning electron microscope, and the morphology of the fluazinam nano sustained-release agent was observed under an accelerating voltage of 3 kV to obtain a SEM image, as shown in the figure. Figure 5 As shown, a and b are SEM images of different areas of the fluazinam nano sustained-release agent.

[0102] Combination Figure 4 and Figure 5 It can be seen that the fluazinam sustained-release agent prepared in Example 11 presents spherical particles with relatively uniform particle size. The particles are smooth in appearance and regular in shape, and there is no agglomeration or severe adhesion between the spheres. The dispersibility of the spherical particles in the field of view of scanning / transmission electron microscopy is good. At the same time, it was found by scanning electron microscopy and transmission electron microscopy that the average size of the nanoparticles is about 200nm.

[0103] Release performance determination of fluazinam sustained-release preparation:

[0104] The release performance of the fluazinam sustained-release agent was determined by the dialysis bag method using 50% ethanol aqueous solution as the simulated release medium and 50% commercially available fluazinam suspension as the control. The specific operation method is as follows.

[0105] Sample preparation: Accurately measure the fluazinam sustained-release agent (suspension) prepared in Example 11 and 50% commercial fluazinam suspension, and place them in two dialysis bags with a molecular weight cut-off of 8000Da and treated. Add 10mL of 50% ethanol aqueous solution to each of the two dialysis bags, and seal the two ends of the dialysis bags firmly with sealing clips, and then place them in 250mL brown reagent bottles. Add 90mL of 50% ethanol aqueous solution to each of the two reagent bottles, immerse the dialysis bags in the ethanol aqueous solution, and the total amount of the solution system in the brown reagent bottle is 100mL. After the brown reagent bottle is sealed, it is transferred to a 25°C constant temperature shaking table and shaken at 300r / min. Take out 5mL of dialysate from the reagent bottle on time according to the set time, and simultaneously supplement 5mL of fresh ethanol aqueous solution with a concentration of 50% in the bottle, so that the solution system in the reagent bottle remains 100mL.

[0106] Standard curve determination: 10 mg of sealed fluazinam original drug standard was diluted with 50% ethanol aqueous solution and fixed to 50 mL to prepare a mother solution with a concentration of 200 μg / mL. Slightly oscillate under ultrasonic conditions to ensure complete dissolution to a uniform and stable state. At room temperature, the prepared mother solution was diluted step by step with 50% ethanol aqueous solution to 5 different concentrations. The specific concentration gradient is: 40 μg / mL, 20 μg / mL, 10 μg / mL, 5 μg / mL, 2.5 μg / mL. First, 3 mL of 50% ethanol aqueous solution was added to the quartz dish as a control and zeroed. Then, the prepared standard solution was added in order from low to high concentration, and its absorbance value was measured at a wavelength of 240 nm using an ultraviolet spectrophotometer. Each sample was measured 3 times and its average value was calculated. After the determination of each concentration of the sample is completed, the quartz dish must be cleaned before the determination of the next concentration standard can be carried out. Finally, the absorbance value obtained by measurement and calculation was linearly fitted with the corresponding standard concentration to obtain the standard curve of fluazinam in 50% ethanol aqueous solution and its correlation. The linear equation is y=0.430930x-0.00711645, and its correlation coefficient R 2 is 0.9999.

[0107] Release value determination: 5 mL of dialysate was taken out on time according to the set time and numbered. The absorbance value of the dialysate was measured by ultraviolet spectrophotometer at a wavelength of 240 nm. The release amount of fluazinam at different times was calculated based on the absorbance value of the dialysate at different times and the standard curve. On this basis, the cumulative release rate was calculated. The results are listed in Table 1, and the cumulative release curve was drawn, as shown in Table 1. Figure 6 shown.

[0108] Table 1 Sustained release properties of fluazinam sustained release agent and commercially available fluazinam suspension in Example 11

[0109]

[0110] Combination Figure 6As can be seen from Table 1, the commercial suspension of fluazinam has a very fast release rate in 50% ethanol aqueous solution, and the cumulative release rate of 25h is close to 80%, while the cumulative release rate of fluazinam sustained-release agent is only about 30%. The cumulative release rate of the commercial suspension of fluazinam has reached 94% at 60h, which is close to complete release, but the cumulative release rate of the sustained-release agent of fluazinam is about 46% at this time, and it can continue to maintain a stable and slow release state for more than 264h. The sustained-release agent of fluazinam shows a certain rapid release state at 1 to 50h, which can achieve a certain rapid effect; at the same time, it can be released slowly and continuously at a relatively stable and balanced speed in the subsequent time, and the duration of effect can be extended to a certain extent. Therefore, the sustained-release agent of fluazinam has a longer release time and more stable slow release performance than the commercial suspension of fluazinam, and can release the active ingredient for a long time at a relatively stable speed, and has the potential to extend the duration of effect. At the same time, the release rate of the fluazinam sustained-release agent can be further adjusted by adjusting parameters such as the thickness of the capsule material and the size of the particle size, so as to achieve coordination between the released dose and the dose required for prevention and treatment.

[0111] Stability determination of fluazinam sustained-release preparation:

[0112] The test determination standards refer to the "General Rules for Pesticide Storage Stability Test at Normal Temperature" (NY / T 1427-2016) and the "National Standard for Pesticide Stability Determination Method" (GB / T 19136-2003). Accurately measure 9 groups of fluazinam sustained-release agents (suspension concentrates) prepared in Example 11 and place them in ground-mouth test tubes for sealing. The 9 groups of samples are divided into 3 parallel tests and stored at three different temperatures. The first parallel group is placed at a temperature of 0±2°C and stored for 7 consecutive days. An appropriate amount of samples are taken out every day to measure their particle size and PDI, and the average value is taken. The second parallel group is placed at a temperature of 25±2°C and stored for 14 consecutive days. An appropriate amount of samples are taken out every two days to measure their particle size and PDI, and the average value is taken. The third parallel group is placed at a temperature of 54±2°C and stored for 14 consecutive days. An appropriate amount of samples are taken out every two days to measure their particle size and PDI, and the average value is taken. The stability of the fluazinam sustained-release agent is evaluated by comparing the particle size and PDI at different times during the storage period. The results are listed in Table 2. A comparison chart is drawn based on Table 2. Figure 7 As shown, a is a comparison chart of the results stored at 0±2°C, b is a comparison chart of the results stored at 25±2°C, and c is a comparison chart of the results stored at 54±2°C.

[0113] Table 2 Stability of the fluridamole sustained-release preparation prepared in Example 11

[0114]

[0115]

[0116] Note: According to the measurement standard, the measurement is performed for 7 days at low temperature and 14 days at room temperature and high temperature, and the test is performed every other day. The blank spaces in the table are the time points where no measurement was performed.

[0117] Combining Table 2 and Figure 7 It can be seen that the fluazinam sustained-release agent can maintain relative stability under three different temperature conditions of 0°C, 25°C and 54°C, and the average particle size varies within 20nm, basically maintaining a relatively uniform level. At the same time, the PDI of the samples under different temperature conditions is less than 0.3, indicating that the fluazinam sustained-release agent can maintain good dispersibility when stored at different temperatures.

[0118] In-house efficacy determination of fluazinam extended-release formulation:

[0119] The biological activity of fluazinam sustained-release agent was determined with clubroot as the test object and cabbage of the fast-growing No. 1 variety (Beijing Zhongshu Seed Co., Ltd.) as the test crop. The soil used during the test was a seedling medium with Brassica root-root fungus, with a bacterial load of 108 dormant spores / gram of medium. Cabbage seedlings were transplanted at a planting density of 5 plants / pot and cultured in a greenhouse environment at about 20°C with a 16h photoperiod. The water content of the medium was 90% in the first 2 weeks after inoculation, and then watered as needed. With clear water as the control, it was applied at an effective ingredient dosage of 100 mg / L and 50 mg / L, respectively. Each treatment was set up with 3 replicates, each replicate was 10 seedlings, and each replicate was arranged in a random block. The soil mixing method was used to apply the medicine, and the dosage required for different concentrations of the agent was calculated. First, add the weighed agent to a small amount of water, stir and mix thoroughly, and then mix thoroughly with the substrate; then sow the germinated cabbage seeds into the bacterial substrate. No other agents for controlling pests and diseases were used in the experiment. Figure 8 As shown, a and b are the actual pictures of the cabbage applied with the fluazinam sustained-release suspension of Example 11 at a mass concentration of 100 mg / L, c and d are the actual pictures of the cabbage applied with the fluazinam sustained-release suspension of Example 11 at a mass concentration of 50 mg / L, and e and f are the actual pictures of the cabbage treated with water. A disease survey was conducted 45 days after the application of the drug, and all plants were surveyed, the natural plant height of the plants was recorded, and the incidence of clubroot was recorded according to the following grading standards.

[0120] Grade 0, no swelling at the root;

[0121] Level 1: Swollen roots are only attached to lateral roots, accounting for 1%-25% of the total root system;

[0122] Level 2: There are swollen roots attached to the main root, and the swollen roots on the lateral roots account for 25%-50%;

[0123] Level 3: There are swollen roots attached to the main root, and the swollen roots account for 50%-75% of the root system;

[0124] Level 4: There are root swellings attached to the main roots, and the swollen roots account for more than 75% of the root system.

[0125] The disease index was calculated based on the disease situation in combination with formula 1, and the prevention and control effect was calculated based on the disease index according to formula 2. The results are listed in Table 3.

[0126] Disease index = ∑[number of plants at each level × representative value of that level] / [total number of plants in the survey × representative value of the highest level] × 100 (Formula 1);

[0127] Preventive effect = (control disease index - treatment disease index) / control disease index × 100% Formula 2.

[0128] Table 3 Efficacy of the fluazinam sustained-release preparation prepared in Example 11

[0129]

[0130] Combining Table 3 and Figure 8 It can be seen that 45 days after application, the effective ingredient content of the fluazinam nano drug delivery system was 100 mg / L and 50 mg / L, and the prevention effect was 91.09% and 83.17% respectively. Therefore, 45 days after application, the fluazinam nano suspension still had a good prevention effect on cabbage clubroot. Since the fluazinam nano sustained-release agent has a longer sustained-release performance, it is beneficial to extend the lasting period while maintaining the efficacy, and is beneficial to reduce the number of soil application, which meets the expectations of the soil application method. At the same time, when the fluazinam nano sustained-release agent is applied at an effective dose of 100 mg / L and 50 mg / L, it is safe for the growth of cabbage.

[0131] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A nano fluazinam sustained-release agent, characterized in that: The invention comprises a sustained-release capsule dispersed in water, wherein the sustained-release capsule is a core-shell structure, the core of the core-shell structure is the fluazinam original drug, and the shell of the core-shell structure is a carrier and a surfactant; the carrier material is ethyl cellulose or polylactic acid; the surfactant comprises one or more of maleated rosin polyoxypropylene oxyethylene ether sulfonate, maleated rosin octylphenol polyoxyethylene ether diester acid sodium salt, polyoxyethylene ether, polyoxyethylene alcohol, polyurethane, polyethylene glycol, polyvinyl alcohol, polyvinyl ether and polyvinyl amide; The mass ratio of the carrier to the surfactant is 3:1.8-2.

2.

2. The fluazinam sustained-release agent according to claim 1, characterized in that: The mass percentage of the fluazinam original drug in the fluazinam sustained-release agent is 0.8-30%.

3. The fluazinam sustained-release agent according to claim 1, characterized in that: The fluazinam sustained-release agent is in the form of spherical particles, and the average particle size of the fluazinam sustained-release agent is 200 to 300 nm.

4. A method for preparing the fluazinam sustained-release preparation according to any one of claims 1 to 3, comprising the following steps: The fluazinam original drug, the carrier and the organic solvent are first mixed to obtain an oil phase; secondly mixing the surfactant and water to obtain an aqueous phase; The oil phase is added into the water phase for emulsification and then the organic solvent is removed to obtain the fluazinam sustained-release agent.

5. The preparation method according to claim 4, characterized in that: The organic solvent includes dichloromethane; The mass ratio of the fluazinam original drug to the carrier is 0.8 to 10:3; The volume ratio of the mass of the fluazinam original drug to the organic solvent is 0.8-30 g:30-100 mL; The mass ratio of the surfactant to water is 1 to 3:

50.

6. The preparation method according to claim 4, characterized in that: The volume ratio of the oil phase to the water phase is 3 to 10:

10.

7. The preparation method according to claim 4 or 6, characterized in that: The emulsification is carried out under ultrasonic conditions, the power of the ultrasound is 500-600W, and the time of the ultrasound is 10-20 minutes.

8. The preparation method according to claim 4, characterized in that: The organic solvent removal is carried out under stirring conditions, the stirring speed is 500-620 r / min, and the stirring time is 18-24 h.

9. Use of the fluazinam sustained-release agent according to any one of claims 1 to 3 or the fluazinam sustained-release agent prepared by the preparation method according to any one of claims 4 to 8 in preventing and treating clubroot.

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