Pyraclostrobin drug-loaded microspheres as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of pesticide preparations, and particularly relates to kresoxim-methyl drug-loaded microspheres as well as a preparation method and application thereof. The 9% pyraclostrobin drug-loaded microspheres (Pyr (at) COzein) are prepared by modifying a Zein-pesticide emulsifier 500 # complex with n-caprylic alcohol, and the n-caprylic alcohol has a synergistic effect on pyraclostrobin, so that not only can the defect of a sustained and controlled release preparation in the aspect of fast-acting sterilization be made up, but also the use dosage of pyraclostrobin can be reduced, the risk of pesticide residue can be reduced, and the drug-loaded microspheres have a good application prospect. The ecological safety is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of pesticide formulations, and particularly relates to a kresoxim-methyl-loaded microsphere and its preparation method and application. Background Art

[0002] As an important disease in rice production, rice blast seriously threatens global food security. Pyraclostrobin, as a broad-spectrum fungicide of the methoxyacrylate class, inhibits the electron transfer of mitochondrial respiratory chain complex III, interferes with the energy metabolism of pathogenic bacteria, and shows excellent control efficacy against Magnaporthe oryzae. However, traditional pyraclostrobin formulations (such as emulsifiable concentrates) have significant defects: its active ingredient is easily degraded by ultraviolet rays on the leaf surface, with a short half-life; rainfall scouring causes a large amount of pesticide loss, and the bioavailability is less than 30%; at the same time, pyraclostrobin has a relatively high acute toxicity to aquatic organisms (such as zebrafish), presenting significant ecological risks.

[0003] In recent years, the pesticide sustained-release and controlled-release system based on natural polymer materials has received much attention. Zein has become an ideal carrier for the pesticide delivery system due to its unique self-assembly characteristics, biodegradability, and drug-loading ability. Research shows that the Zein-based drug-loading system can encapsulate pesticide molecules through hydrophobic interaction and delay the release of active ingredients, but its single component has problems such as poor stability and low drug-loading efficiency. In the prior art, the performance is often improved by surfactant composite modification. For example, Nongru 500# can improve the emulsibility of Zein, but the composite system still faces technical bottlenecks such as the contradiction between the slow-release rate and the quick-acting bactericidal property, and poor erosion resistance due to insufficient interfacial binding force.

[0004] It is worth noting that the application of synergists provides a new idea for reducing pesticide dosage and increasing efficiency. n-Octanol is a kind of co-surfactant, which has been proven to have antibacterial effects on some pathogenic bacteria. However, the prior art mostly uses simple physical mixing methods, which have problems such as easy volatilization of synergistic components and poor compatibility with carriers, and it is difficult to achieve precise loading and stable release of synergistic components in nano-carriers. How to integrate n-octanol into the Zein-Nongru 500# composite system through molecular design to construct an intelligent drug-loading system with both slow-release characteristics and quick-acting bactericidal functions has become the key to breaking through the existing technical bottlenecks.

[0005] In summary, developing a new type of drug-loading microsphere system based on the modification of natural materials and the synergistic effect of integrating synergists, while improving the leaf retention and photo-stability of pyraclostrobin, and reducing its toxicity to non-target organisms, is of great significance for achieving precise pesticide control and sustainable agricultural development. Summary of the Invention

[0006] Aiming at the problems existing in the prior art, the present invention provides a pyraclostrobin-loaded microsphere, a preparation method thereof and an application thereof. In the present invention, pyraclostrobin is used as the test pesticide, and n-octanol is used to modify the complex formed by zein and agricultural emulsifier 500# to construct a 9% pyraclostrobin loading system (Pyr@COzein). The synergistic effect of n-octanol on pyraclostrobin in Pyr@COzein, the foliar application performance of Pyr@COzein and the safety to non-target organisms are comprehensively evaluated, providing new ideas for the prevention and control of foliar diseases by pesticide sustained-release systems.

[0007] The present invention is realized through the following technical solutions: A preparation method of a pyraclostrobin-loaded microsphere, comprising the following steps: S1. Accurately weigh zein, agricultural emulsifier 500#, cyclohexanone, n-octanol, pyraclostrobin and water, and fully mix and dissolve them to obtain an oil phase; S2. Accurately weigh sodium lignosulfonate and dissolve it in deionized water to obtain an aqueous phase; S3. Add the oil phase to the aqueous phase, and perform shear homogenization with a shear emulsification homogenizer to obtain a pyraclostrobin-loaded microsphere preparation, denoted as Pyr@COzein.

[0008] Further, the mass ratio of zein to agricultural emulsifier 500# is 1:1. As an anionic surfactant, agricultural emulsifier 500# can reduce the interfacial tension of zein particles, and the two form a uniform complex through electrostatic interaction; Further, the mass fraction of n-octanol in the preparation is 3-7%.

[0009] Further, the mass ratio of cyclohexanone to n-octanol is 3:1.

[0010] Further, the mass ratio of agricultural emulsifier 500# to sodium lignosulfonate is 10:1.

[0011] Further, the conditions for shear homogenization are shear homogenization for 3 min under the condition of 14000 r / min.

[0012] Further, the mass fraction of pyraclostrobin in the preparation is 9%.

[0013] The present invention also provides a pyraclostrobin-loaded microsphere prepared by using the above preparation method, and the Pyr@COzein-loaded microsphere is a coexistence system of micro-nano particles.

[0014] The present invention also provides an application of the pyraclostrobin-loaded microsphere in the prevention and control of Magnaporthe oryzae.

[0015] The beneficial technical effects of the present invention: (1) Through the molecular synergistic effect of n-octanol and pyraclostrobin, the bactericidal activity of the present invention is significantly improved, and the synergistic efficiency coefficient reaches 2.66. The EC 50 value (6.57 μg / L) is reduced by 41.5% compared with the original drug (11.24 μg / L), breaking through the bottleneck of the insufficient quick-acting property of the traditional slow-release system and realizing the synergistic effect of "slow-release - quick-acting" dual functions.

[0016] (2) The drug-loaded microspheres of the present invention have a coexisting structure of micro-nano particles (nanoparticles 848 nm, micron particles 9.12 μm). Through the multi-scale interface anchoring effect, the retention rate of foliar pesticides is increased by 1.45 times compared with emulsifiable concentrate (PyrEC) (residual 50.84% vs 23.38% after 10 minutes of flushing). Combining with the light shielding effect of the carrier, the anti-photolysis performance is increased by 2.05 times (residual 53.80% vs 28.17% after 6 hours), significantly extending the prevention and control window period.

[0017] (3) The controllable biodegradable characteristics of the carrier material of the present invention avoid environmental residues. At the same time, the microsphere encapsulation increases the acute toxicity LC 50 value of pyraclostrobin to zebrafish from 42.96 μg / L (PyrEC) to 67.37 μg / L, reducing the ecological risk by 36.8%.

[0018] (4) The drug-loaded microspheres of the present invention have no significant effect on the physiological indexes such as the fresh weight and plant height of rice plants (p<0.05), and realize target disease-oriented delivery through the pH-responsive release mechanism (72-hour cumulative release rate 78.3%). Under the simulated rainfall - strong light combined stress, it still maintains a 75% control effect, which is 1 time higher than that of emulsifiable concentrate (37.5%).

[0019] The present invention realizes the molecular-level synergistic integration of pesticide synergists and natural carrier materials for the first time, providing an integrated solution with high efficiency, low risk, and environmental intelligent response for foliar disease prevention and control. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 For the basic performance characterization of Pyr@COzein; (A) Appearance of the preparation; (B) SEM; (C) TEM; (D) Particle size distribution; (E) FTIR spectrum; (F) TGA curve; (G) Release curve and encapsulation efficiency.

[0021] Figure 2 For the bioactivity determination results of Pyr@COzein; Figure 3 For the determination results of the erosion resistance performance of Pyr@COzein; Figure 4 For the determination results of the anti-photolysis performance of Pyr@COzein; Figure 5 Determination of the control effect before and after flushing and photolysis of Pyr@COzein: (A) Control effect of Pyr@COzein before and after flushing and photolysis; (B) Infection status of leaves before and after flushing and photolysis; Figure 6 Note on the greenhouse control effect of Pyr@COzein: (A) Greenhouse control effect of Pyr@COzein under light conditions; (B) Greenhouse control effect of Pyr@COzein under light-rain conditions; (C) Infection status of leaves under different days of light / light-rain conditions; Figure 7 Diagram for the determination of the plant safety of Pyr@COzein; Figure 8 Diagram for the determination results of the zebrafish safety of Pyr@COzein; Figure 9 Diagram for the evaluation results of the carrier degradation behavior of Pyr@COzein. Specific implementation mode

[0022] Test materials Table 1. Purity and source of test materials

[0023] Example 1 First, 2.50 g of Zein, 2.50 g of agricultural emulsion 500#, 7.50 g of cyclohexanone, 2.50 g of n-octanol, 4.55 g of pyraclostrobin, and 1.00 g of water, which were accurately weighed, were fully mixed and dissolved to obtain an oil phase; 0.25 g of sodium lignosulfonate was accurately weighed and dissolved in 29.20 g of deionized water to obtain an aqueous phase. The oil phase was added to the aqueous phase, and shear homogenization was carried out for 3 min at 14000 r / min using a shear emulsification homogenizer to obtain a 9% pyraclostrobin-loaded microsphere preparation, denoted as Pyr@COzein-1.

[0024] Example 2 First, 2.50 g of Zein, 2.50 g of agricultural emulsion 500#, 7.50 g of cyclohexanone, 1.50 g of n-octanol, 4.55 g of pyraclostrobin, and 1.00 g of water, which were accurately weighed, were fully mixed and dissolved to obtain an oil phase; 0.25 g of sodium lignosulfonate was accurately weighed and dissolved in 29.20 g of deionized water to obtain an aqueous phase. The oil phase was added to the aqueous phase, and shear homogenization was carried out for 3 min at 14000 r / min using a shear emulsification homogenizer to obtain a 9% pyraclostrobin-loaded microsphere preparation, denoted as Pyr@COzein-2.

[0025] Example 3 First, 2.50 g of Zein, 2.50 g of agricultural emulsion 500#, 7.50 g of cyclohexanone, 2.0 g of n-octanol, 4.55 g of pyraclostrobin, and 1.00 g of water were accurately weighed and fully mixed and dissolved to obtain an oil phase; 0.25 g of sodium lignosulfonate was accurately weighed and dissolved in 29.20 g of deionized water to obtain an aqueous phase. The oil phase was added to the aqueous phase, and shear homogenization was carried out at 14000 r / min for 3 min using a shear emulsification homogenizer to obtain a 9% pyraclostrobin-loaded microsphere preparation, denoted as Pyr@COzein-3.

[0026] (1)Characterization of the basic properties of the drug-loaded microspheres: In this invention, n-octanol was used to modify the complex formed by Zein and agricultural emulsion 500# to prepare 9% pyraclostrobin-loaded microspheres (Pyr@COzein). The appearance of the preparation is as Figure 1 shown in A. The particle size measurement results are as Figure 1 shown in D and Table 2. The results show that Pyr@COzein is a coexistence system of micro- and nano-particles. The average sizes of the nanoparticles and microparticles prepared in Example 1 are 848 nm and 9.12 μm, respectively. The average sizes of the nanoparticles and microparticles prepared in Example 2 are 715 nm and 21.23 μm, respectively. The average sizes of the nanoparticles and microparticles prepared in Example 3 are 598 nm and 16.24 μm, respectively. As the amount of n-octanol increases, the overall particle size of the micro-formulation shows a downward trend because n-octanol belongs to a co-surfactant, and an increase in its amount can effectively reduce the particle size of the formulation.

[0027] Table 2. Particle sizes of the drug-loaded microspheres prepared in Examples 1-3

[0028] The morphology of Pyr@COzein-1 prepared in Example 1 is as Figure 1 shown in B and C. The results show that Pyr@COzein-1 has good dispersibility, and the particles maintain a uniform and plump spherical structure. The results of Fourier transform infrared spectroscopy (FTIR) are as Figure 1 shown in E. The characteristic peaks of zein are the amide I band and amide II band at 1540 cm -1 and 1654 cm -1 respectively, and the characteristic peak of pyraclostrobin is the C-Cl stretching vibration peak at 741 cm -1 respectively. These characteristic peaks were all detected in the drug-loaded microspheres, indicating that Pyr@COzein-1 was successfully prepared and loaded with pyraclostrobin. The results of the thermal degradation curve show that ( Figure 1F), compared with the original drug directly exposed to high temperature conditions, at the same temperature, the weight loss of pyraclostrobin loaded on the drug-loaded microspheres was significantly reduced, indicating that Pyr@COzein-1 has an obvious thermal protection effect on pyraclostrobin, indirectly proving the effective loading of the drug-loaded microspheres on pyraclostrobin.

[0029] (2)Evaluation of the indoor antibacterial biological activity of Pyr@COzein The mycelial growth rate method was used to determine the sensitivity of Magnaporthe oryzae to the drug-loaded microspheres of Pyr@COzein. The compounding ratio of pyraclostrobin and n-octanol was 9:5. N-octanol, the original drug of pyraclostrobin, and pyraclostrobin·n-octanol were all dissolved in acetone and added to the PDA medium after dilution with acetone. Five concentration gradients of 1 μg / L, 2 μg / L, 4 μg / L, 8 μg / L, and 16 μg / L were set in the experiment, and the antibacterial concentrations of n-octanol alone were set at 25 mg / L, 50 mg / L, 100 mg / L, 200 mg / L, and 400 mg / L. A sterile puncher was used to cut a 5-mm-diameter agar disc from the edge of the Magnaporthe oryzae colony and inoculate it in the center of the drug-containing PDA plate with the mycelial side facing down. All plates were placed in a constant temperature incubator at 27 °C and cultured in the dark for 7 d. The colony diameter was measured by the cross-cross method, and the mycelial growth inhibition rate and synergistic coefficient were calculated according to the formula. Each treatment was repeated 4 times.

[0030]

[0031] The synergistic coefficient (SR) of n-octanol on pyraclostrobin was calculated by the following formula:

[0032] A and B represent each component respectively, and a and b are the proportions of each component in the fungicide formulation. The effect of the fungicide compounding was analyzed according to the SR value. If SR is greater than 1.5, it is a synergistic effect; if SR is less than 1.5, it is an antagonistic effect.

[0033] The pesticide sustained-release control system can achieve continuous and precise control of diseases, but its slow-release characteristics may lead to a decrease in the rapid bactericidal effect. To solve this key problem, n-octanol was introduced into the drug-loading system in this invention, and the key role of n-octanol in the drug-loaded microspheres was evaluated. The antibacterial effect of Pyr@COzein on Magnaporthe oryzae showed that ( Figure 2 Table 3, Table 4), n-octanol has good antibacterial activity, and the EC of n-octanol, Pyr, PyrEC, pyraclostrobin·n-octanol, Pyr@COzein-1, Pyr@COzein-2, and Pyr@COzein-3 against Magnaporthe oryzae 50The values are 144.59 mg / L, 11.24 μg / L, 10.31 μg / L, 9.50 μg / L, 6.57 μg / L, 8.54 μg / L, and 7.8 μg / L respectively.

[0034] The co - efficiency (SR) was used to evaluate the synergistic effect between different agents. The results showed that n - octanol had a synergistic effect on pyraclostrobin, showing better antibacterial activity than PyrEC, making up for the deficiency of the slow - release preparation in the rapid control of diseases. The synergistic coefficient of pyraclostrobin·n - octanol was 1.84, and the synergistic coefficient of Pyr@COzein was 2.66. The synergistic effect of nanoparticles in Pyr@COzein further enhanced the bactericidal activity against Magnaporthe oryzae.

[0035] Table 3. Mycelial inhibition rate (%) of different agents against Magnaporthe oryzae in rice and EC 50

[0036] Table 4. Mycelial inhibition rate (%) of different concentrations of n - octanol against Magnaporthe oryzae in rice and EC 50

[0037] (3)Determination of the erosion - resistant performance of Pyr@COzein - 1 The long - term efficacy of the drug - loaded microspheres depends not only on their good slow - release performance but also on the retention ability of the drug - loaded microspheres in the natural environment. For the pesticide foliar delivery system, improving the erosion - resistant performance of the preparation is a key parameter for effective control. In this study, by simulating strong rainfall conditions, the leaf retention stability of Pyr@COzein - 1 was systematically evaluated. The results of the residual amount of pyraclostrobin on rice leaves showed that ( Figure 3 ) Pyr@COzein - 1 showed good erosion - resistant effects. There were significant differences in the pesticide residue rates of PyrEC and Pyr@COzein - 1 on the surface of rice leaves. After 2 minutes of flushing, the pesticide residue rates of PyrEC and Pyr@COzein - 1 on the leaves were 25.50% and 62.66% respectively, and decreased to 23.38% and 50.84% respectively after 10 minutes of flushing. This was because Pyr@COzein - 1 had a relatively high adhesion force, reducing the loss of pesticides caused by rainwater flushing.

[0038] (4)Determination of the photolysis - resistant performance of Pyr@COzein - 1 To evaluate the photostability of pyraclostrobin in the loaded state, the photolysis - resistant performance of Pyr@COzein - 1 was determined in this invention. The results of the residual amount of pyraclostrobin on the glass slide showed that ( Figure 4), The anti-photodegradation ability of Pyr@COzein-1 is significantly better than that of PyrEC. Experimental data shows that after 30 min of ultraviolet irradiation, the pesticide residue rates of PyrEC and Pyr@COzein-1 are 56.50% and 86.91% respectively, and they drop to 28.17% and 53.80% respectively after 6 h, indicating that Pyr@COzein-1 can effectively shield ultraviolet radiation, enhance the photostability of pyraclostrobin, and improve the foliar retention performance of pyraclostrobin.

[0039] (5)Control effect of Pyr@COzein-1 after flushing and photolysis Considering that the control effect of fungicides is related to their exposure state and retention amount on the leaf surface, the present invention evaluated the in vitro control effects of PyrEC and Pyr@COzein-1 on Magnaporthe oryzae before and after flushing and ultraviolet degradation treatments. Before and after 2 min of flushing and 0.5 h of ultraviolet irradiation, the infection state of rice leaves by Magnaporthe oryzae was as Figure 5 shown. The results show that under different treatments (unflushed / photolyzed, flushed, photolyzed), the control effect of Pyr@COzein-1 on Magnaporthe oryzae is significantly higher than that of PyrEC. The control effects of Pyr@COzein-1 on rice blast are 87.5%, 83.33% and 83.33% respectively, which are significantly higher than the control effects of PyrEC of 58.33%, 29.16% and 33.33%. The experimental results show that under strong light and rainfall conditions, the rapid loss of the active ingredient in PyrEC leads to a decrease in its control effect. Pyr@COzein-1 has good photostability and foliar retention performance for pyraclostrobin, and its foliar steady-state retention performance is strong, and it can still maintain a good control effect under complex environmental conditions.

[0040] (6)Antibacterial activity of Pyr@COzein-1 in greenhouse pot experiments Based on the good anti-flushing effect and photostability of Pyr@COzein-1, the pot control effect of Pyr@COzein-1 on Magnaporthe oryzae was evaluated. The results show that under the condition of not simulating rain flushing ( Figure 6 A), Pyr@COzein-1 showed a good long-lasting effect. The control effects of PyrEC and Pyr@COzein-1 on rice blast in the first 5 days were both above 80%, with no significant difference; on the 7th day after spraying, the control effect of Pyr@COzein-1 was significantly higher than that of PyrEC. The control effect of PyrEC on rice blast dropped to 68.75%, and the control effect of Pyr@COzein-1 on Magnaporthe oryzae remained at 87.5%. Under the condition of simulating rain flushing ( Figure 6B), similar to the non-rainfall group, there was no significant difference in the control efficacy of PyrEC and Pyr@COzein-1 in the first 5 days, but there was a certain downward trend compared with the non-rainfall group, and the control efficacy against rice blast was about 75%; at the 7th day, the protective effect of PyrEC on rice decreased significantly, and the control efficacy was only 37.5%, and the rice leaves were severely infected ( Figure 6 C), the control efficacy of Pyr@COzein-1 still remained at 75%, which was 1 time higher than that of PyrEC, indicating that Pyr@COzein-1 significantly prolonged the retention amount of pyraclostrobin on the leaves and improved the utilization rate of pyraclostrobin under simulated natural condition stress.

[0041] (7)Safety of Pyr@COzein-1 to plants In the process of optimizing the performance of pesticide delivery systems, systematic evaluation of their crop safety and environmental compatibility is crucial. In this invention, the safety of Pyr@COzein-1 to rice plants was systematically evaluated by measuring the key physiological indexes of rice plants. As Figure 7 shown, under the treatment conditions of different concentrations of PyrEC and Pyr@COzein-1, the growth of rice plants showed no obvious abnormality. Compared with the clear water control, there was no significant difference in the fresh weight, dry weight, plant height and root length of rice plants in the Pyr@COzein-1 group (p<0.05). The research results show that while maintaining excellent antibacterial activity, Pyr@COzein has no adverse effect on the physiological growth of rice seedlings, showing good crop safety.

[0042] (8)Determination of the safety of Pyr@COzein-1 to non-target organisms The high biological activity of pesticides is often accompanied by potential harm to non-target organisms, which raises important considerations for their environmental safety. In this invention, the ecological toxicity of Pyr@COzein-1 to non-target organism zebrafish was evaluated. The results of the death of zebrafish under the treatment of different concentrations of PyrEC and Pyr@COzein-1 show that ( Figure 8 , Table 5), the LC 50 values of PyrEC and Pyr@COzein-1 to zebrafish are 42.96 μg / L and 67.37 μg / L respectively, indicating that through the drug-loaded microsphere encapsulation technology, the direct contact between pyraclostrobin and zebrafish is blocked, and the acute toxicity of pyraclostrobin to zebrafish is significantly reduced. This finding provides an important experimental basis for evaluating the environmental safety of pesticide-loaded microspheres.

[0043] Table 5. Mortality rate (%) of zebrafish and LC 50

[0044] Degradation behavior of Pyr@COzein-1 carrier The degradability of proteins in the environment makes them a green drug-loading material with broad application prospects, avoiding the potential long-term pollution problems caused by traditional synthetic materials. An appropriate amount of sample diluent was evenly smeared on the glass slides respectively. After natural drying, the glass slides were placed in 50 mL centrifuge tubes containing blank, 30 mL deionized water, and 30 mL soil bacterial solution (the soil was mixed with water, shaken well, filtered to remove impurities, and then the bacterial solution was diluted to 1×103 cfu / mL). After 24 h, they were taken out. After natural drying, an imaging microscope was used to observe and record the microscopic morphology of the drug-loaded microspheres.

[0045] The degradation results of Pyr@COzein-1 under simulated natural environment show that ( Figure 9 ), in a dry environment, Pyr@COzein-1 can still maintain its original morphological structure at 24 h; when the drug-loaded microspheres are in an aqueous environment, the drug-loaded microspheres are significantly degraded, and only a large carrier skeleton remains after 24 h; microorganisms such as bacteria in the soil will accelerate the degradation process of the carrier, and the carrier is completely degraded after 24 h. The research results show that the compound modification of zein with Nongru 500# does not change the inherent biodegradable properties of zein, and the Zein-Nongru 500# composite system as a pesticide loading material is environmentally safe.

[0046] In the present invention, n-octanol was used to modify the Zein-Nongru 500# complex to prepare 9% pyraclostrobin-loaded microspheres (Pyr@COzein). N-octanol has a synergistic effect on pyraclostrobin, which can not only make up for the deficiency of sustained-release and controlled-release preparations in terms of rapid bactericidal effect, but also reduce the dosage of pyraclostrobin, reduce the risk of pesticide residues, and improve ecological safety.

[0047] In the present invention, n-octanol was introduced into the pyraclostrobin sustained-release and controlled-release system to produce a synergistic effect. Compared with PyrEC, the synergistic coefficient of pyraclostrobin·n-octanol is 1.84. The synergistic effect of nanoparticles in Pyr@COzein further enhances the bactericidal activity against Magnaporthe oryzae, and the synergistic coefficient is 2.66. This result provides an important reference for the development of new pesticide formulations with high efficiency, low toxicity, and long-lasting effects.

[0048] The drug-loaded microspheres constructed using the Zein-Nongru 500# complex in the present invention do not affect the degradability of zein itself and do not cause any pollution residues; due to the adhesion effect of the drug-loaded microspheres in the early stage, a large amount of pyraclostrobin remains on the leaf surface and is photolyzed by ultraviolet light during the gradual degradation of the microspheres, which is environmentally safe. At the field application dose of Pyr@COzein, it does not cause phytotoxicity to rice plants and is safe for the plants; the results of the non-target toxicity determination of Pyr@COzein show that the loading of pyraclostrobin by the drug-loaded microspheres reduces its toxicity to zebrafish (by 0.57 times), indicating that while Pyr@COzein has high biological activity, it does not cause high harm to non-target organisms and is eco-friendly.

Claims

1. A preparation method of pyraclostrobin-loaded microspheres, characterized in that: It includes the following steps: S1. Accurately weigh zein, agricultural emulsifier 500#, cyclohexanone, n-octanol, pyraclostrobin and water, and fully mix and dissolve them to obtain an oil phase; S2. Accurately weigh sodium lignosulfonate and dissolve it in deionized water to obtain an aqueous phase; S3. Add the oil phase to the aqueous phase, and perform shear homogenization with a shear emulsification homogenizer to obtain a pyraclostrobin-loaded microsphere preparation, denoted as Pyr@COzein.

2. The preparation method of the pyraclostrobin-loaded microspheres according to claim 1, wherein: The mass ratio of Zein to agricultural emulsifier 500# is 1:

1.

3. The preparation method of the pyraclostrobin-loaded microspheres according to claim 1, characterized in that: The mass fraction of n-octanol in the preparation is 3-5%.

4. The preparation method of the pyraclostrobin-loaded microspheres according to claim 1, wherein: The mass ratio of cyclohexanone to n-octanol is 3:

1.

5. The preparation method of the pyraclostrobin-loaded microspheres according to claim 1, characterized in that: The mass ratio of agricultural emulsifier 500# to sodium lignosulfonate is 10:

1.

6. The preparation method of the pyraclostrobin-loaded microspheres according to claim 1, characterized in that: The conditions for shear homogenization are shear homogenization for 3 min under the condition of 14000 r / min.

7. The preparation method of the pyraclostrobin-loaded microspheres according to claim 1, wherein: The mass fraction of pyraclostrobin in the preparation is 9%.

8. A pyraclostrobin-loaded microsphere prepared by the preparation method according to any one of claims 1-7, characterized in that: The Pyr@COzein-loaded microspheres are a coexistence system of micro- and nano-particles.

9. Use of the pyraclostrobin-loaded microspheres prepared by the preparation method according to any one of claims 1-7 in the prevention and control of Magnaporthe oryzae.

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