Preparation method of pesticide preparation beneficial to leaf surface adhesion and product

Abstract

The preparation method comprises the following steps: 1) dissolving polyoxyethylene polyoxypropylene in ethanol to prepare a template agent solution, adding a dopamine hydrochloride solution with the concentration of 0.5-20 mg / mL, mixing the two solutions, adding a pore-enlarging agent, carrying out ultrasonic treatment to form a uniform emulsion system, rapidly adding ammonia water drop by drop, carrying out ultrasonic treatment at the temperature of 60-80 DEG C, carrying out ultrasonic treatment at the temperature of 60-80 DEG C, and carrying out suction filtration; and continuously stirring at room temperature, reacting for 2-24 hours, centrifuging and washing to obtain the mPDA pesticide carrier. (2) dispersing the mPDA pesticide carrier obtained in the step (1) in ethanol and water, and carrying out ultrasonic treatment, so that the mPDA pesticide carrier is fully dispersed in the water to form a uniform and stable dispersion liquid; 3) adding a biopesticide into ethanol and pure water to completely dissolve the biopesticide to obtain a biopesticide solution, slowly dropwise adding the biopesticide solution into the dispersion liquid obtained in the step 2), and continuously stirring and reacting for 12-48 hours at room temperature; and 4) after the reaction is finished, collecting the precipitate, washing the precipitate with absolute ethyl alcohol, and drying the precipitate to obtain the mPDA pesticide preparation.

Description

Technical Field

[0001] This invention belongs to the field of pesticides and relates to a method for preparing a pesticide formulation that facilitates leaf adhesion and a product thereof. Background Technology

[0002] Pesticides are indispensable in agricultural production, serving as crucial "weapons" to ensure crop yields and safety. With the advancement of agricultural modernization, the application of nanotechnology in pesticide formulation has provided a new breakthrough in overcoming key technological bottlenecks in traditional formulations. Nanocarriers significantly improve pesticide application efficacy by enhancing pesticide solubility, improving formulation stability, and optimizing release kinetics. However, existing pesticide formulations still suffer from several drawbacks: insufficient leaf adhesion leading to generally low pesticide retention rates after rainwater runoff; poor photostability, with most pesticides exhibiting short half-lives under ultraviolet radiation; and inadequate sustained-release properties, resulting in initial burst release.

[0003] Currently, nanopesticide carriers are inorganic mesoporous materials (such as silica, mesoporous carbon, and alumina) and organic polymers (such as polylactic acid-glycolic acid copolymer (PLGA), chitosan, and starch-based materials). While these carriers possess high specific surface area or slow-release properties, they still suffer from poor biocompatibility and adhesion. Furthermore, although protein nanoparticles (such as zein and silk fibroin) and liposomes exhibit good adhesion and biocompatibility, their limited specific surface area restricts drug loading efficiency. Therefore, developing pesticide carriers that combine high leaf adhesion and high drug loading capacity has become a research hotspot.

[0004] Polydopamine nanospheres with mesoporous structures combine the unique properties of mesoporous materials and dopamine. Their abundant phenolic hydroxyl and amino groups on the surface enable strong interactions with plant leaves, enhancing adhesion. Simultaneously, the broad-spectrum UV absorption characteristics of polydopamine (200-800 nm) can effectively slow down the photolysis rate of pesticides. This integrated structure-function property provides a large specific surface area and abundant pore structure, which is beneficial for the efficient loading and controlled release of pesticide active ingredients. Therefore, how to fully leverage these advantages to solve existing problems in pesticide formulation remains an important direction for further exploration. Summary of the Invention

[0005] In view of this, the present invention provides a method for preparing a pesticide formulation that facilitates leaf adhesion. Specifically, the present invention provides the following technical solution:

[0006] 1. A method for preparing a pesticide formulation that facilitates leaf adhesion, comprising the following steps:

[0007] 1) Polyoxyethylene and polyoxypropylene are dissolved in ethanol to prepare a template agent solution. Dopamine hydrochloride solution with a concentration of 0.5-20 mg / mL is added. The two solutions are mixed and a pore-expanding agent is added. The mixture is ultrasonically treated to form a homogeneous emulsion system. Ammonia water is added dropwise rapidly and continuously stirred at room temperature for 2-24 hours. The mixture is then centrifuged and washed to obtain the mPDA pesticide carrier.

[0008] 2) Take the mPDA pesticide carrier from step 1), disperse it in ethanol and water, and sonicate it to fully disperse the mPDA pesticide carrier in water to form a uniform and stable dispersion.

[0009] 3) Add the biopesticide to ethanol and pure water to dissolve it completely, and obtain a biopesticide solution. Slowly add the biopesticide solution dropwise to the dispersion in step 2), and continue stirring the reaction at room temperature for 12-48 hours.

[0010] 4) After the reaction is complete, collect the precipitate, wash the precipitate with anhydrous ethanol, dry the precipitate, and obtain the mPDA pesticide formulation.

[0011] Furthermore, the mass ratio of polyoxyethylene, polyoxypropylene and dopamine in step 1) is 3:1-10:1.

[0012] Furthermore, the mass ratio of polyoxyethylene, polyoxypropylene and dopamine in step 1) is 6:1 to 1:1.

[0013] Further, the pore-expanding agent mentioned in step 1) is one or a mixture of several of 1,3,5-trimethylbenzene, n-decane, n-hexane, urea, polyethylene glycol, and polyvinylpyrrolidone.

[0014] Further, in step 1), the mass ratio of the pore-expanding agent to dopamine is 3:1 to 1:10, and the mass ratio of ammonia water to dopamine is 1:10 to 1:100.

[0015] Furthermore, in step 2), the volume ratio or mass ratio of ethanol to pure water is 1:2-4:1.

[0016] Furthermore, in step 2), the concentration of the mPDA pesticide carrier is 1-10 mg / mL.

[0017] Furthermore, in step 3), the mass ratio of the added biopesticide to the mPDA pesticide carrier is 10:1 to 1:10.

[0018] Furthermore, in step 3), the mass ratio of the biopesticide to the mPDA pesticide carrier is 4:1 to 1:2.

[0019] 2. The pesticide formulation prepared by the above preparation method has a usage concentration of 5-20 mg / mL and a usage volume of less than 50 μL.

[0020] The beneficial effects of this invention are as follows: Regarding adhesion performance, the mPDA pesticide formulation of this invention is regularly spherical with a uniform particle size distribution, a uniform surface mesoporous structure, and a tendency towards surface densification. It exhibits a good wetting-adhesion balance on leaf surfaces, spreading evenly and adhering firmly. Even when the bamboo leaf surface is at a 180° angle, the formulation will not drip or run off, demonstrating excellent retention, adhesion, and hydrophobic compatibility, effectively improving pesticide utilization. Therefore, the pesticide formulation prepared by this invention can improve the adhesion and retention performance of pesticides on leaf surfaces. Regarding photostability, the inherent light absorption characteristics of the mPDA pesticide carrier can effectively shield ultraviolet light, reduce photodegradation of pesticide active ingredients, and improve the weather resistance of the formulation. Therefore, the pesticide formulation of this invention enables pesticides to maintain stability under strong light conditions, prolonging the field residual effect and further improving pesticide utilization efficiency. Regarding sustained-release properties, the mesoporous structure of the mPDA pesticide carrier regulates the pesticide release rate, exhibiting continuous and stable sustained-release characteristics. This prolongs the action time of the pesticide's active ingredient, thereby improving the persistence of control effects while reducing the frequency of application and lowering environmental risks. In summary, the pesticide formulation of this invention achieves a synergistic improvement in high adhesion, photostability, and controllable sustained release, providing new ideas for the development of efficient and environmentally friendly pesticide formulations. Attached Figure Description

[0021] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following figures are provided:

[0022] Figure 1 SEM images of pesticide carriers and pesticide formulations;

[0023] Figure 2 This is a DLS diagram of pesticide carriers and pesticide formulations.

[0024] Figure 3 The contact angle of the mPDA pesticide formulation on a glass slide and fresh bamboo leaves.

[0025] Figure 4 This is an image showing the adhesion of mPDA pesticide formulations to bamboo leaves.

[0026] Figure 5 The results show the adhesion performance of different concentrations of mPDA pesticide formulations and different nanocarriers on bamboo leaves.

[0027] Figure 6 The adhesion properties of mPDA pesticide formulations of different volumes on bamboo leaves were investigated.

[0028] Figure 7 The curve shows the change in mass of mPDA pesticide formulation on bamboo leaves over time.

[0029] Figure 8The residue of different concentrations of mPDA pesticide formulations on bamboo leaves.

[0030] Figure 9 The UV absorption spectra of berberine, osthol, matrine, kasugamycin, ivermectin, and abamectin, as well as the UV absorption spectra of mPDA pesticide carriers and mPDA pesticide formulations.

[0031] Figure 10 This refers to the pesticide loading and encapsulation efficiency of mPDA pesticide formulations.

[0032] Figure 11 This is a release diagram of mPDA pesticide formulations. Detailed Implementation

[0033] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0034] Example 1: Preparation of mPDA pesticide carrier

[0035] Weigh out 100 mg of polyoxyethylene polyoxypropylene (Pluronic F-127) and dissolve it in 3 mL of ethanol to prepare a template agent solution. Add 3 mL of a 10 mg / mL dopamine hydrochloride solution to the above Pluronic F-127 solution and stir for 10 minutes to ensure that the dopamine is uniformly dispersed in the solution. Mix the two solutions and add 60 μL of 1,3,5-trimethylbenzene (TMB) as a pore-expanding agent. Sonicate for 3 minutes to form a homogeneous emulsion system. Rapidly add 300 μL of ammonia water dropwise and stir continuously at room temperature for 2 hours. Centrifuge and wash three times with anhydrous ethanol / ultrapure water (v / v = 1:1) mixture, centrifuging at 20000 g for 10 minutes each time to obtain the mPDA pesticide carrier.

[0036] Example 2: Preparation of mPDA pesticide formulation

[0037] 1) Take 4 mg of the mPDA pesticide carrier prepared in Example 1, disperse it in 2 mL of ethanol and water, and sonicate for 20 minutes to fully disperse the mPDA pesticide carrier in water and form a uniform and stable nanosphere dispersion. The sonication treatment can effectively break the agglomeration between nanospheres and ensure its uniformity in the subsequent loading process.

[0038] 2) Weigh 8 mg of biological pesticide (berberine, osthol, matrine, kasugamycin, ivermectin, or abamectin), add 2 mL of ethanol and 2 mL of pure water respectively, and stir for 10 minutes to completely dissolve them to obtain a solution. Slowly add the berberine, osthol, matrine, kasugamycin, ivermectin, or abamectin solution dropwise to the dispersion of the mPDA pesticide carrier in Example 1, and continue stirring at room temperature for 12 hours. During this process, berberine molecules are loaded onto the mPDA pesticide carrier through physical adsorption, chemical bonding, and electrostatic interaction.

[0039] 3) After the reaction was completed, the product was transferred to a centrifuge tube and centrifuged at 20,000 g for 10 minutes to collect the precipitate. The precipitate was washed three times with anhydrous ethanol, and centrifuged at 20,000 g for 10 minutes after each wash to remove unloaded berberine. Then, the dispersion was dried by freeze drying to obtain the mPDA pesticide formulation.

[0040] Comparative Example 1: Preparation of Pesticide Carrier

[0041] Weigh out 50 mg of polyoxyethylene polyoxypropylene (Pluronic F-127) and dissolve it in 3 mL of ethanol to prepare a template agent solution. Add 3 mL of a 5 mg / mL dopamine hydrochloride solution to the above Pluronic F-127 solution and stir for 10 minutes to ensure that the dopamine is uniformly dispersed in the solution. Mix the two solutions and add 60 μL of 1,3,5-trimethylbenzene (TMB) as a pore-expanding agent. Sonicate for 3 minutes to form a homogeneous emulsion system. Rapidly add 300 μL of ammonia water dropwise and stir continuously at room temperature for 30 minutes. Centrifuge and wash three times with anhydrous ethanol / ultrapure water (v / v = 1:1) mixture, centrifuging at 20000 g for 10 minutes each time to obtain the pesticide carrier mPDA.

[0042] Comparative Example 2: Preparation of Pesticide Carriers

[0043] Weigh out 50 mg of polyoxyethylene polyoxypropylene (Pluronic F-127) and dissolve it in 3 mL of ethanol to prepare a template agent solution. Add 3 mL of a 5 mg / mL dopamine hydrochloride solution to the above Pluronic F-127 solution and stir for 10 minutes to ensure that the dopamine is uniformly dispersed in the solution. Mix the two solutions and add 60 μL of 1,3,5-trimethylbenzene (TMB) as a pore-expanding agent. Sonicate for 3 minutes to form a homogeneous emulsion system. Rapidly add 300 μL of ammonia water dropwise and stir continuously at room temperature for 1 hour. Centrifuge and wash three times with anhydrous ethanol / ultrapure water (v / v = 1:1) mixture, centrifuging at 20000 g for 10 minutes each time to obtain the pesticide carrier mPDA.

[0044] Comparative Example 3: Preparation of Pesticide Carriers

[0045] Weigh out 100 mg of polyoxyethylene polyoxypropylene (Pluronic F-127) and dissolve it in 3 mL of ethanol to prepare a template agent solution. Add 3 mL of a 10 mg / mL dopamine hydrochloride solution to the above Pluronic F-127 solution and stir for 10 minutes to ensure that the dopamine is uniformly dispersed in the solution. Mix the two solutions and add 60 μL of 1,3,5-trimethylbenzene (TMB) as a pore-expanding agent. Sonicate for 3 minutes to form a homogeneous emulsion system. Rapidly add 300 μL of ammonia water dropwise and allow the reaction to stand at room temperature for 2 hours (without stirring). Centrifuge and wash three times with anhydrous ethanol / ultrapure water (v / v = 1:1) mixture, centrifuging at 20000 g for 10 minutes each time to obtain the pesticide carrier mPDA.

[0046] Comparative Example 4: Preparation of Pesticide Carrier PDA

[0047] 40 mg of dopamine was uniformly dispersed in 100 mL of 0.5 MN, N-dihydroxyethylglycine (Bicine) pH 8.5 buffer solution and reacted in the dark for 12 hours. After centrifugation, the sample was washed three times with ultrapure water and centrifuged at 20000 g for 10 minutes to obtain the pesticide carrier PDA. Comparative Example 5: Preparation of pesticide carrier SiO2-DA

[0048] 1) Dissolve 1.2 g of tris(hexadecyl)methylammonium chloride (CTAC) in 24 mL of deionized water beforehand. Add 36 mL of deionized water and 0.18 g of triethanolamine (TEA) to a 100 mL round-bottom flask, add the dissolved CTAC, and stir at 400 rpm and 60 °C for 1 hour. Add 20 mL of cyclohexane containing 10% (v / v) tetraethyl orthosilicate (TEOS) dropwise along the wall, and stir at 400 rpm and 60 °C for 12 hours. Stop the reaction, let stand for 30 minutes, pour the liquid into a centrifuge tube, aspirate the upper oil phase, add an equal volume of anhydrous ethanol to the aqueous phase, centrifuge at 9000 rpm for 15 minutes, discard the supernatant, wash and collect the product, add 20 mL of ethanol solution, sonicate for 5 minutes, centrifuge at 9000 rpm for 30 minutes, discard the supernatant, and repeat the washing twice. Remove CTAC, add 20 mL of 1% hydrochloric acid-ethanol solution, sonicate for 15 minutes, centrifuge at 9000 rpm for 30 minutes, repeat washing twice, and resuspend in 20 mL of ethanol to obtain nano-silica (SiO2) with a particle size of 20-50 nm.

[0049] 2) Disperse 40 mg of the prepared SiO2 evenly in 20 mL of 0.5 MN, N-dihydroxyethylglycine (Bicine) pH=8.5 buffer solution, add 200 μL of 50 mg / mL dopamine solution, react for 12 hours, centrifuge and wash three times with ultrapure water, centrifuge at 20000 g for 10 minutes to obtain pesticide carrier SiO2-DA.

[0050] Comparative Example 6: Preparation of pesticide carrier nCaCO3-DA

[0051] 1) Add 0.3 g / mL of polyaspartic acid (PASP) solution to 500 mL of 0.1 M CaCl2 reaction solution. Mix the two solutions for 30 minutes to allow the PASP to react with the CaCl2. 2+ To form a polymer precursor solution, add 25 mg / mL of polyacrylic acid (PAA) solution to 500 mL of 0.1 M Na₂CO₃ reaction solution. Mix the two solutions for 30 minutes to allow the PAA to react with the CO₃²⁻. 2- A polymer precursor solution was formed. The feed rates were set at 165 L / min and 180 L / min, respectively, and pumped into a centrifugal rotating packed bed at a frequency of 35.008 Hz. The reactants were collected. The resulting product was centrifuged at 8500 rpm for 20 min, washed, and dried to obtain nano-calcium carbonate (nCaCO3) with a particle size of 50-100 nm.

[0052] 2) Disperse 80 mg of the prepared nCaCO3 evenly in 40 mL of 0.5 MN, N-dihydroxyethylglycine (Bicine) pH=8.5 buffer solution, add 400 μL of 50 mg / mL dopamine solution, react for 12 hours, centrifuge, wash 3 times with ultrapure water, centrifuge at 20000 g for 10 minutes to obtain the pesticide carrier nCaCO3-DA.

[0053] Comparative Example 7: Preparation of pesticide carrier nHAP-DA

[0054] 1) Prepare a 0.1 mol / L CaCl2 solution, a 0.06 mol / L Na2HPO4·12H2O solution, a 15 mg / mL polyaspartic acid (PASP) solution, and a 25 mg / mL polyacrylic acid (PAA) solution. Mix the PASP solution and CaCl2 solution at a volume ratio of 10:1 and chelate for 30 minutes, denoted as solution A. Mix the PAA solution and Na2HPO4·12H2O solution at a volume ratio of 5:1 and chelate for 30 minutes, denoted as solution B. Keep the volumes of CaCl2 solution and Na2HPO4·12H2O solution the same. Place solutions A and B separately at the inlet of a centrifuge, with a feed flow rate ratio of 11:12 and a rotation speed of 2500 rpm / min. Collect the samples at the outlet. Place the above sample in a centrifuge at 8500 rpm / min for 10 minutes, discard the liquid, and wash with water three times to obtain nano-hydroxyapatite (nHAP) with a particle size of 50-100 nm.

[0055] 2) Disperse 80 mg of the prepared nHAP evenly in 40 mL of 0.5 MN, N-dihydroxyethylglycine (Bicine) pH=8.5 buffer solution, add 400 μL of 50 mg / mL dopamine solution, react for 12 hours, centrifuge, wash 3 times with ultrapure water, centrifuge at 20000 g for 10 minutes to obtain the pesticide carrier nHAP-DA.

[0056] Test Example 1 Morphological Characterization

[0057] The mPDA pesticide carrier prepared in Example 1, the mPDA pesticide formulation prepared in Example 2, the mPDA pesticide carrier prepared in Comparative Example 1, the mPDA pesticide carrier prepared in Comparative Example 2, and the mPDA pesticide carrier prepared in Comparative Example 3 were prepared into a 0.5 mg / mL solution. After ultrasonic treatment, 5 μL was pipetted onto a silicon wafer (10 × 10 mm) and dried. After gold sputtering, the morphology was measured on a Japanese ultra-high resolution field emission scanning electron microscope (SEM) SU8600 series.

[0058] Figure 1 SEM images of the pesticide carrier and pesticide formulation are shown. The results indicate that the mPDA pesticide carrier prepared in Example 1 is a regular sphere with a uniformly distributed honeycomb-like mesoporous structure on its surface. Figure 1 a) The mPDA pesticide formulation prepared in Example 2 (i.e., the pesticide loaded onto the mPDA pesticide carrier) exhibits a regular spherical structure, but the mesoporous structure disappears after pesticide loading, and the surface tends to become denser. Figure 1 b).

[0059] The mPDA pesticide carrier prepared in Comparative Example 1 had an irregular morphology and no mesopores. Figure 1 c). This is because, in the preparation of the pesticide carrier in Comparative Example 1, the stirring time after adding ammonia was only 30 minutes, which is too short, far less than the 2-24 hours claimed in this invention. Since the oxidative polymerization of dopamine under alkaline conditions requires sufficient time to complete the reaction, insufficient reaction time will lead to incomplete polymerization of the monomers, forming amorphous aggregates instead of spherical shapes.

[0060] The mPDA pesticide carrier prepared in Comparative Example 2 showed improved shape regularity, but mesoporous structures were still not formed. Figure 1 d). This is because, in the preparation of the pesticide carrier in Comparative Example 2, the stirring time after adding ammonia was only 1 hour, which is too short, far less than the 2-24 hours claimed in this invention. Due to the insufficient reaction time, amorphous aggregates were formed instead of spherical shapes.

[0061] Furthermore, because the mPDA pesticide carrier forms a mesoporous template through micelle self-assembly, the critical micelle concentration (CMC) and its dosage of the template agent determine the pore structure. When the dosage of the template agent (polyoxyethylene polyoxypropylene, 50 mg) in Comparative Examples 1 and 2 is insufficient, the micelles cannot form a continuous phase, resulting in the absence of mesopores.

[0062] The mPDA pesticide carrier prepared in Comparative Example 3 initially showed a spherical structure and a small number of mesopores, but the mesopores were unevenly distributed and had poor regularity. Figure 1 e). Analysis: The reaction time was sufficient (reaching 2 hours), and dopamine under alkaline conditions underwent oxidative polymerization, forming well-defined spheres. The amount of template agent (polyoxyethylene polyoxypropylene, 100 mg) was within the appropriate range, resulting in a mesoporous structure. However, due to the lack of stirring after the addition of ammonia, the template agent and monomers were unevenly distributed. Micelles, constrained by Brownian motion, formed regional aggregations, which also affected the local concentration of dopamine, leading to inconsistent polymerization rates and the formation of disordered channels.

[0063] Test Example 2 Particle Size Characterization

[0064] The mPDA pesticide carrier prepared in Example 1 or the mPDA pesticide formulation prepared in Example 2 was prepared into a 0.5 mg / mL solution, dispersed in phosphate buffer (10 mM, pH 7.0), and its particle size was determined on a Zetasizer Nano ZS 90.

[0065] Figure 2 This is a DLS diagram of pesticide carriers and pesticide formulations. Figure 2 a is the mPDA pesticide carrier prepared in Example 1. Figure 2 b represents the mPDA pesticide formulation prepared in Example 2 (i.e., the pesticide loaded onto the mPDA pesticide carrier). Figure 2 As can be seen, the average particle size of the mPDA pesticide carrier is 145 nm. Figure 2 a) The average particle size of mPDA pesticide formulations is 205 nm. Figure 2 b) and the particle size distribution is uniform (PDI less than 0.2).

[0066] Test Example 3: Contact Angle Measurement

[0067] Using an Optical Surface Analyser OSA60SO contact angle measuring instrument and workstation, volume parameters were set, and the mPDA pesticide formulation prepared in Example 2 was dropped onto glass slides and fresh bamboo leaves at room temperature (25℃±1℃). A pesticide solution was added as a control. Droplet morphology was measured and recorded. The software automatically fitted the Young-Laplace equation to calculate the static contact angle. Five different sites were measured for each sample, and the average value was taken.

[0068] Figure 3 The contact angles of the mPDA pesticide formulation on a glass slide and fresh bamboo leaves are shown. The results indicate that the pesticide formulation prepared in Example 2 has a contact angle of approximately 30° on the glass slide, lower than the pesticide's 38.88°, indicating good wettability. On the bamboo leaf surface, the contact angle is 70°, lower than the pesticide's 80.87°, demonstrating that the pesticide formulation of this invention has superior hydrophobic compatibility compared to traditional pesticide solutions.

[0069] Test Example 4: Adhesion Measurement on Bamboo Leaves

[0070] Gently rinse the bamboo leaves with ultrapure water to remove dust, then blow dry. Add 50 μL of the mPDA pesticide formulation prepared in Example 2. The added pesticide solution serves as a control. Use a Canon EOS 5D Mark IV to photograph and observe the two formulations at leaf tilt angles of 0°, 30°, 60°, 90°, and 180°.

[0071] Figure 4 This is an adhesion diagram of mPDA pesticide formulations on bamboo leaves. From... Figure 4 As can be seen, the mPDA pesticide formulation of the present invention did not drip or run off the bamboo leaf surface at a temperature ranging from 0 to 180°, while the pesticide solution dripped and ran off at a temperature of 90°. This data indicates that the mPDA pesticide formulation of the present invention has extremely strong adhesion.

[0072] Figure 5 The results show the adhesion performance of different concentrations of mPDA pesticide formulations and different nanocarriers on bamboo leaves.

[0073] The adhesion properties of different concentrations of mPDA pesticide formulations prepared in Example 2 (20 mg / mL, 10 mg / mL, 5 mg / mL, 2.5 mg / mL, 1 mg / mL, and 0 mg / mL) were evaluated. The specific procedure was as follows: different concentrations of mPDA pesticide formulations were dropped onto the surface of bamboo leaves, and the leaf tilt angle was adjusted from 0° to 180°. Continuous photography was conducted using a Canon EOS 5D Mark IV camera during the angle change process. The maximum tilt angle at which the formulation did not drip or run off was used as the core evaluation index. The statistical results are shown below. Figure 5 As shown in a.

[0074] Figure 5 'a' represents the statistical analysis of the maximum tilt angle at which different concentrations of mPDA pesticide formulations do not drip or run off onto bamboo leaves. From... Figure 5As shown in Figure a, the results indicate that the mPDA pesticide formulation prepared in Example 2 can maintain a 180° non-drip and non-bleeding state on the bamboo leaf surface at high concentrations of 20 mg / mL, 10 mg / mL, and 5 mg / mL, confirming its excellent and stable leaf surface adhesion ability. However, at low concentrations of 2.5 mg / mL and 1 mg / mL, dripping and bleeding only occurred at a 90° tilt, indicating that the adhesion ability decreases significantly with decreasing concentration. High concentrations of mPDA pesticide formulations (5-20 mg / mL) can reduce pesticide loss due to rainwater runoff and prolong the residual effect.

[0075] To demonstrate the superior adhesion performance of the mPDA pesticide formulation prepared in Example 2, leaf adhesion performance tests were conducted under the same conditions as those of the pesticide carriers prepared in the comparative examples (nCaCO3, SiO2, nHAP, PDA, nCaCO3-DA, SiO2-DA, nHAP-DA). The specific procedures were as follows: pesticide carriers of different concentrations were dropped onto the surface of bamboo leaves, and the leaf tilt angle was adjusted from 0° to 180°. Continuous photography was performed using a Canon EOS 5D Mark IV camera during the angle change process. The maximum tilt angle at which the formulation did not drip or run off was used as the core evaluation index. The statistical results are shown below. Figure 5 As shown in b.

[0076] Figure 5 b represents the adhesion properties of different nanocarriers on bamboo leaves. From... Figure 5 As can be seen from b:

[0077] The PDA prepared in Comparative Example 4 could maintain a 180° angle without dripping or flowing off the bamboo leaf surface at concentrations of 20 mg / mL and 10 mg / mL. However, when the concentration was reduced to 5 mg / mL, the droplets began to drip and flow off the bamboo leaf surface when tilted at 90°. Its adhesion performance decreased with decreasing concentration.

[0078] The nCaCO3 (20 mg / mL) prepared in Comparative Example 5 dripped off the bamboo leaf surface at a 90° angle.

[0079] The SiO2 (20 mg / mL) prepared in Comparative Example 6 dripped off the bamboo leaf surface at a 70° angle.

[0080] The nHAP (20 mg / mL) prepared in Comparative Example 7 dripped off the bamboo leaf surface at an angle of 80°.

[0081] This indicates that the inherent surface properties of different inorganic nanomaterials (such as hydrophilicity / hydrophobicity, surface charge, etc.) directly affect their adhesion stability on the blade surface.

[0082] After modifying the above-mentioned nCaCO3, SiO2, and nHAP with dopamine, the resulting nCaCO3-DA, SiO2-DA, and nHAP-DA were tested:

[0083] The nCaCO3-DA (20 mg / mL) prepared in Comparative Example 5 could maintain a 180° angle on the bamboo leaf surface without dripping or flowing away. However, when the concentration was reduced to 10 mg / mL, it dripped and flowed away when the bamboo leaf surface was at a 90° angle.

[0084] The SiO2-DA (20 mg / mL) prepared in Comparative Example 6 dripped off the bamboo leaf surface at an angle of 110°.

[0085] The nHAP-DA (20 mg / mL) prepared in Comparative Example 7 was dripped and lost when the surface of the bamboo leaf was at 90°.

[0086] Therefore, sufficient material concentration is a crucial prerequisite for maintaining the high adhesion performance after dopamine modification. The adhesion ability of all three nanomaterials was enhanced to varying degrees after modification. However, their adhesion ability is still insufficient compared to mPDA pesticide formulations.

[0087] In summary, compared with conventional nanocarriers and nanocarriers modified only with dopamine, the mPDA pesticide formulation prepared by this patent has significant advantages in leaf adhesion performance.

[0088] Test Example 5: Study on the effect of pesticide formulation volume on adhesion properties

[0089] In practical spraying applications, spraying will produce droplets of different sizes, and the droplet volume will affect the adhesion effect of pesticides. In order to investigate the effect of the volume of the mPDA pesticide formulation prepared in Example 2 of this invention on its adhesion performance, a systematic adhesion performance test was carried out using a 20 mg / mL concentration formulation as the object. Figure 6 The adhesion properties of mPDA pesticide formulations of different volumes on bamboo leaves were investigated.

[0090] Figure 6 The results showed that when the volume of the mPDA pesticide formulation prepared in Example 2 was in the range of 0-50 μL, it maintained stable adhesion to the bamboo leaf surface when tilted at 180° without dripping or running off. However, when the volume increased to 60 μL, dripping and running off occurred when the bamboo leaf surface was tilted at 90°. Further observation revealed that as the formulation volume continued to increase, the critical tilt angle for dripping and running off gradually decreased, indicating that its adhesion stability on the leaf surface was significantly negatively correlated with the formulation volume.

[0091] The results demonstrate that the mPDA pesticide formulation prepared in Example 2 has extremely strong leaf adhesion ability within the volume range (≤50μL) and can resist gravity to maintain adhesion; however, beyond this volume threshold, gravity exceeds the adhesion force threshold, causing the formulation to easily fall off.

[0092] Test Example 6: Leaf Retention Test of Pesticide Formulations

[0093] Gently rinse the bamboo leaves with ultrapure water to remove dust, then blow dry. Add the mPDA pesticide formulation prepared in Example 2. The added pesticide solution serves as a control. Weigh and record the amounts within 0-6 hours. The retention amount of the pesticide formulation on the bamboo leaf surface was determined to correspond to the residual amount. Repeat 5 times, using the residual amount of the pesticide solution (without pesticide carrier loading) on ​​the leaf surface as a control. Allow the leaves to air dry, and prepare homogeneous suspensions of the pesticide formulation at different concentrations. After measuring the dry weight of the leaf surface using an electronic balance, completely immerse the leaf surface in the corresponding concentration suspension for 5 minutes, recording the mass when no more droplets fall from the leaf surface. Calculate the residual amount (R) for each experimental group using the following formula.

[0094]

[0095] Where: R represents the amount of liquid retained on the leaf surface (mg / cm³) 2 W1 represents the dry weight of the leaf surface (mg); W2 represents the wet weight of the leaf surface (mg); S represents the area of ​​the leaf surface (cm²). 2 ).

[0096] Figure 7 The graph shows the mass change of the mPDA pesticide formulation on bamboo leaves over time. Dynamic monitoring of the formulation mass change on the bamboo leaf surface over time revealed that, during a continuous observation period of 6 hours, the pesticide formulation mass loss rate was only 40%, while the pesticide solution (control) loss rate was 97%. This demonstrates that the mPDA pesticide formulation exhibits good retention stability on the leaf surface, indicating that the pesticide formulation of this invention demonstrates excellent long-lasting adhesion.

[0097] Figure 8 The residue levels of different concentrations of mPDA pesticide formulations on bamboo leaves are shown. Data from the residue measurements of different concentrations of mPDA pesticide formulations prepared in Example 2 indicate that the pesticide residue level on the bamboo leaf surface increases significantly with increasing pesticide concentration gradient.

[0098] This result indicates that there is a positive correlation between the concentration of mPDA pesticide formulations and their retention capacity on the leaf surface. Higher concentrations of formulations are more likely to form better adhesion on the bamboo leaf surface, reducing loss caused by environmental factors (such as rain erosion and leaf shaking).

[0099] Test Example 7: Determination of pesticide loading and encapsulation efficiency of pesticide formulations

[0100] The absorption wavelengths of pesticides were determined using a UV spectrophotometer. The absorbance of berberine was measured at 350 nm, osthol at 322 nm, matrine at 210 nm, ivermectin at 245 nm, abamectin at 245 nm, and kasugamycin at 205 nm. The absorbance of each standard solution was also measured. A standard curve was plotted with pesticide concentration on the x-axis and absorbance on the y-axis, and the regression equation was calculated.

[0101] Centrifugation method was used to determine the pesticide loading and encapsulation efficiency: The pesticide carrier prepared in Example 1 was co-incubated with the pesticide. The pesticide formulation obtained after incubation was centrifuged at 20,000 rpm for 10 minutes. The precipitate was the pesticide formulation of Example 2. The absorbance of the supernatant was measured to determine the unencapsulated free pesticide. The centrifugation was repeated 3 times, and the free pesticide concentration was calculated by substituting the values ​​into the standard curve.

[0102]

[0103] Among them, W drug W represents the amount of pesticide loaded. mPDA This refers to the total weight of the pesticide carrier.

[0104]

[0105] W loaded drug W represents the actual pesticide loading capacity within the nanospheres. totaldrug This refers to the total mass of pesticides.

[0106] Figure 9 The UV absorption spectra of berberine, osthol, matrine, kasugamycin, ivermectin, and abamectin, as well as the UV absorption spectra of mPDA pesticide carriers and mPDA pesticide formulations.

[0107] Figure 9 a represents the ultraviolet absorption spectra of berberine, osthol, matrine, kasugamycin, ivermectin, and abamectin. Figure 9 b shows the ultraviolet absorption spectra of the mPDA pesticide carrier and the mPDA pesticide formulation.

[0108] from Figure 9 As shown in Figure b, the mPDA pesticide carrier prepared in Example 1 exhibits strong UV-Vis absorption in the 200-800 nm range, which can effectively slow down the photolysis rate of pesticides. The mPDA pesticide formulation prepared in Example 2 shows strong UV-Vis absorption (200-800 nm) of the mPDA pesticide carrier, and also has a specific absorption peak for berberine pesticide, proving that the pesticide was successfully loaded and can effectively slow down the photolysis rate of berberine pesticides.

[0109] Most synthetic pesticides, such as organophosphates, pyrethroids, and triazoles, are highly susceptible to photochemical degradation in the UV (200-400 nm) wavelength range, leading to reduced efficacy. Therefore, the mPDA pesticide carrier of this invention can effectively slow down the photodegradation rate of pesticides.

[0110] Figure 10 This refers to the pesticide loading and encapsulation efficiency of mPDA pesticide formulations. From... Figure 10 As can be seen from the results, the mPDA pesticide carrier prepared in Example 1 of the present invention has a pesticide loading capacity of up to 73% for berberine and an encapsulation rate of up to 54%; a pesticide loading capacity of up to 73% for kasugamycin and an encapsulation rate of up to 56%; a pesticide loading capacity of up to 75% for osthol and an encapsulation rate of up to 61%; a pesticide loading capacity of up to 69% for matrine and an encapsulation rate of up to 46%; a pesticide loading capacity of up to 68% for ivermectin and an encapsulation rate of up to 42%; and a pesticide loading capacity of up to 58% for abamectin and an encapsulation rate of up to 29%. This demonstrates that the pesticide carrier of the present invention has excellent pesticide loading capacity.

[0111] Test Example 8: Determination of the in vitro release performance of pesticide formulations

[0112] A dialysis bag with a molecular weight cutoff of 8000-14000 Da was selected. 10 mg of the mPDA pesticide formulation prepared in Example 2 was accurately weighed and placed into the pretreated dialysis bag. The dialysis bag containing the pesticide formulation was placed in 50 mL of release medium, which was ethanol. Different temperatures were set to simulate the ambient temperature of different seasons and regions. At predetermined time points, 1 mL of release medium was taken as a sample, and an equal volume of fresh medium was added to maintain a constant release medium volume. After sampling, the OD value was measured at the maximum absorption wavelength using a UV spectrophotometer, and the free pesticide concentration was calculated by substituting the values ​​into a standard curve.

[0113] Figure 11 This is a release diagram of mPDA pesticide formulations. From Figure 11 It can be seen from this:

[0114] The mPDA pesticide formulation prepared in Example 2 exhibited sustained-release characteristics, with a cumulative release rate of approximately 35-85% over 72 hours. The cumulative release rates for berberine at different temperatures (25℃, 35℃, 45℃) were 37%, 58%, and 85%, respectively; for kasugamycin, 53%, 75%, and 80%; for osthol, 45%, 64%, and 79%; for matrine, 43%, 63%, and 78%; for ivermectin, 30%, 39%, and 72%; and for abamectin, 19%, 37%, and 71%. Therefore, the pesticide formulation of the present invention can achieve long-term controlled release of pesticides.

[0115] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A method for preparing a pesticide formulation that facilitates leaf adhesion, characterized in that the preparation steps are as follows: 1) Polyoxyethylene and polyoxypropylene are dissolved in ethanol to prepare a template agent solution. Dopamine hydrochloride solution with a concentration of 0.5-20 mg / mL is added. The two solutions are mixed and a pore-expanding agent is added. The mixture is ultrasonically treated to form a homogeneous emulsion system. Ammonia water is added dropwise rapidly and continuously stirred at room temperature for 2-24 hours. The mixture is then centrifuged and washed to obtain the mPDA pesticide carrier. 2) Take the mPDA pesticide carrier from step 1), disperse it in ethanol and water, and sonicate it to fully disperse the mPDA pesticide carrier in water to form a uniform and stable dispersion. 3) Add the biopesticide to ethanol and pure water to dissolve it completely, and obtain a biopesticide solution. Slowly add the biopesticide solution dropwise to the dispersion in step 2), and continue stirring the reaction at room temperature for 12-48 hours. 4) After the reaction is complete, collect the precipitate, wash the precipitate with anhydrous ethanol, dry the precipitate, and obtain the mPDA pesticide formulation.

2. The method for preparing a pesticide formulation that facilitates leaf adhesion according to claim 1 is characterized in that the mass ratio of polyoxyethylene polyoxypropylene and dopamine in step 1) is 3:1-10:

1.

3. The method for preparing a pesticide formulation that facilitates leaf adhesion according to claim 1 is characterized in that the mass ratio of polyoxyethylene polyoxypropylene and dopamine in step 1) is 6:1-1:

1.

4. The method for preparing a pesticide formulation that facilitates leaf adhesion according to claim 1 is characterized in that the pore-expanding agent in step 1) is one or a mixture of several of 1,3,5-trimethylbenzene, n-decane, n-hexane, urea, polyethylene glycol, and polyvinylpyrrolidone.

5. The method for preparing a pesticide formulation that facilitates leaf adhesion according to claim 1 is characterized in that the mass ratio of the pore-expanding agent to dopamine in step 1) is 3:1-1:10, and the mass ratio of the amount of ammonia added to dopamine is 1:10-1:

100.

6. The method for preparing a pesticide formulation that facilitates leaf adhesion according to claim 1 is characterized in that the volume ratio or mass ratio of ethanol and pure water in step 2) is 1:2-4:

1.

7. The method for preparing a pesticide formulation that facilitates leaf adhesion according to claim 1 is characterized in that the concentration of the mPDA pesticide carrier in step 2) is 1-10 mg / mL.

8. The method for preparing a pesticide formulation that facilitates leaf adhesion according to claim 1 is characterized in that the mass ratio of the amount of biological pesticide added in step 3) to the mass ratio of the mPDA pesticide carrier is 10:1 to 1:

10.

9. The method for preparing a pesticide formulation that facilitates leaf adhesion according to claim 1 is characterized in that the mass ratio of the biological pesticide to the mPDA pesticide carrier in step 3) is 4:1-1:

2.

10. The pesticide formulation prepared by any one of the preparation methods according to claims 1-9 is characterized in that the concentration of the pesticide formulation used is 5-20 mg / mL and the volume used is within 50 μL.

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