Amphiphilic double-sided nanoparticles, methods of making and using the same

Abstract

The application provides an amphiphilic double-sided nanoparticle and a preparation method and application thereof. The amphiphilic double-sided nanoparticle can improve the stability of Pickering emulsion, meanwhile, can improve the effective deposition of a pesticide on a plant leaf, realizes quick-acting prevention and treatment, and has a good application prospect.

Description

Technical Field

[0001] This invention relates to the field of pesticides, specifically to pesticides, and particularly to a Pickering emulsion containing amphiphilic Janus nanoparticles, its preparation method, and its application. Background Technology

[0002] Wheat, as a major global food crop, plays a crucial role in meeting growing food demand and promoting economic growth. However, wheat stem base rot, a widespread fungal disease primarily caused by *Fusarium graminearum*, poses a serious threat to global wheat production. This pathogen rapidly infects the stem base and spreads upwards to the ear, infecting and damaging the vascular bundles, thus hindering the transport of water and nutrients. This leads to reduced tillering, increased stem brittleness, and ultimately severe yield losses. Due to the current lack of widely applicable resistant varieties, chemical control remains the primary means of controlling wheat stem base rot. According to data from the Food and Agriculture Organization of the United Nations, pesticide application has reduced global food losses by approximately 30% to 40%. However, developing green, efficient, and sustainable pesticide formulations remains a significant challenge. During application, traditional formulations suffer significant losses, with only about 40% of the pesticide deposited on the surface of the target crop. Of this, approximately 80% is concentrated in the upper and middle canopy of the wheat plant, while less than 2% reaches the stem base. Furthermore, adverse weather conditions, especially rainfall, can severely reduce the adhesion of pesticide solutions to leaf surfaces, ultimately leading to bioavailability of active ingredients on target organisms as low as 0.1%. To achieve effective disease control, it is often necessary to increase the frequency and dosage of pesticide application. This practice not only results in significant resource waste but also poses serious risks to food safety and ecological integrity.

[0003] Nanoparticle delivery technology provides an important pathway to improve the target accessibility and utilization efficiency of pesticide active ingredients and has been widely used in the control of plant diseases and pests. However, most functional nanocarriers still face challenges such as limited drug loading capacity, stringent preparation and application conditions, and high costs for large-scale production. Introducing a small amount of solid nanoparticles into traditional high-drug-loading emulsifiable concentrate systems and using them to replace or partially replace molecular surfactants in the preparation of Pickering emulsions provides a feasible strategy to balance the interfacial function of nanomaterials with the feasibility of manufacturing conventional formulations. For example, the paper "Empowering alkali lignin with high performance inpickering emulsion by selective phenolation for the protection and controlled-release of agrochemicals" (J Clean Prod, 2022, 339) discloses the use of lignin nanoparticles to stabilize avermectin-pickerlin emulsion, improving the active ingredient's resistance to UV and oxidative degradation and enhancing its leaf adhesion. The paper "Selenium-Doped Biomass-Based Nanoparticles Drive Agricultural Emulsions toward a Novel "Offense-Defense Integration" Strategy" (Advanced Functional Materials, 2025) discloses the construction of propiconazole-pickerlin emulsion using selenium-doped zein nanoparticles, achieving multifunctional pesticide delivery and effective control of Botrytis cinerea. These studies demonstrate that particle-stabilized emulsions can reshape the interfacial properties and leaf surface delivery behavior of pesticide droplets, but their stability and functional limits are still constrained by the interfacial structure of the particles used.

[0004] Specifically, isotropic particles lack directional constraints on wettability at the oil-water interface, making them prone to interfacial rearrangement or desorption. To maintain emulsion stability, it is often necessary to increase the particle dosage or introduce additional surfactants, thereby increasing formulation complexity and potentially weakening the functional expression of particles during leaf surface deposition, adhesion, and penetration. In contrast, amphiphilic Janus nanoparticles possess a spatially separated hydrophilic-hydrophobic chemical composition, enabling orientation-selective adsorption at the oil-water interface and inhibiting particle migration and droplet co-aggregation through a higher interfacial desorption energy barrier. Their interfacial adsorption energy is three times that of isotropic particles with similar composition, making them suitable as highly efficient solid emulsifiers. However, existing research mainly focuses on the contribution of Janus particles to the formation and storage stability of Pickering emulsions. There is still a lack of systematic understanding of how Janus particles determine the deposition, retention, and transepidermal delivery of active ingredients on target leaves by regulating the bulk rheological properties of the pesticide solution, droplet dynamic impact behavior, and the interaction between the pesticide solution and the leaf interface. Therefore, it is of great scientific significance and application value to develop Janus particle-stabilized pesticide formulations that combine high pesticide loading capacity, low dependence on molecular adjuvants, stable spray performance, and efficient foliar delivery. Summary of the Invention

[0005] This invention provides a solid foundation for the preparation of stable pesticide Pickering emulsions (JNPs PE) by constructing amphiphilic bifacial (Janus) nanoparticles to replace traditional molecular adjuvants.

[0006] The specific technical solution of this invention is to improve an amphiphilic bifacial (Janus) nanoparticle, wherein the amphiphilic bifacial (Janus) nanoparticle is mPEG-P-MSNs@PS JNPs (polyethylene glycol modified polydopamine-doped silica@polystyrene Janus nanoparticles).

[0007] This invention also provides a method for preparing mPEG-P-MSNs@PS JNPs (polyethylene glycol-modified polydopamine-doped silica@polystyrene Janus nanoparticles), characterized by comprising the following steps:

[0008] Step 1) Preparation of PS (polystyrene) nanoparticles

[0009] Step 2) Preparation of P-MSNs@PS NPs (polydopamine-doped silica@polystyrene nanoparticles);

[0010] Step 3) Preparation of P-MSNs@PS JNPs (polydopamine-doped silica@polystyrene Janus (double-sided) nanoparticles);

[0011] Step 4) Preparation of mPEG-P-MSNs@PS JNPs (polyethylene glycol modified polydopamine-doped silica@polystyrene Janus (double-sided) nanoparticles).

[0012] In addition, the present invention also provides a Pickering emulsion comprising pesticide, mPEG-P-MSNs@PS JNPs and solvent, wherein the solvent is water and / or an organic solvent, preferably, the water is deionized water.

[0013] This invention also provides the application of the Pickering emulsion of this invention in the prevention and control of plant diseases.

[0014] Beneficial effects

[0015] 1. The amphiphilic Janus nanoparticles provided by this invention are mPEG-P-MSNs@PS JNPs (polyethylene glycol modified polydopamine-doped silica@polystyrene Janus nanoparticles), which can replace ordinary additives to obtain stable Pickering emulsions.

[0016] 2. The Pickering emulsion containing mPEG-P-MSNs@PS JNPs (polyethylene glycol-modified polydopamine-doped silica@polystyrene Janus nanoparticles) of the present invention has storage stability and high efficiency of leaf-surface interface, effectively inhibiting the breakage and rebound of spray droplets on wheat leaves, increasing effective deposition and leaf adhesion.

[0017] 3. The Pickering emulsion of mPEG-P-MSNs@PS JNPs (polyethylene glycol modified polydopamine-doped silica@polystyrene Janus nanoparticles) of the present invention allows pesticides to be effectively deposited on plant leaves, increasing the efficiency of in vivo transport and the accumulation of active ingredients in the base of wheat stems and roots, thereby achieving rapid and effective prevention and control. Attached Figure Description

[0018] Figure 1 Scanning electron microscopy images showing the effect of tetrahydrofuran volume fraction and stirring time on the formation of polyethylene glycol-modified polydopamine-doped silica@polystyrene bifacial nanoparticles.

[0019] Figure 2 (a) Scanning electron microscope (SEM) image of polydopamine-doped silica@polystyrene double-sided nanoparticles; (b) Transmission electron microscope (TEM) image of polydopamine-doped silica@polystyrene double-sided nanoparticles; (c) Scanning electron microscope (SEM) image of polyethylene glycol-modified polydopamine-doped silica@polystyrene double-sided nanoparticles; (d) Energy dispersive spectroscopy (EDS) image of polydopamine-doped silica@polystyrene double-sided nanoparticles.

[0020] Figure 3Particle size distribution of the polystyrene portion and the polydopamine-doped silica portion of polyethylene glycol-modified polydopamine-doped silica@polystyrene double-sided nanoparticles.

[0021] Figure 4 Optical microscopic images of a polydopamine-doped silica@polystyrene double-sided nanoparticle-stabilized difenoconazole-pickerlin emulsion (JNPs PE) with different oil phase mass fractions: (a1) ωo=1 / 5, (a2) ωo=2 / 5, (a3) ​​ωo=1 / 2, (a4) ωo=3 / 5, (a5) ωo=4 / 5. (The mass fraction ω is an internationally accepted standard symbol used to represent the ratio of solute mass to total solution mass; here, ωo refers to the proportion of the oil phase to the total formulation mass.)

[0022] Figure 5 Macroscopic images of JNPs PE prepared from polydopamine-doped silica@polystyrene bifacial nanoparticle-stabilized phenyl ether tebuconazole Pickering emulsion (JNPs PE) with different oil phase mass fractions.

[0023] Figure 6 Viscosity curves of Pickering emulsion JNPs PE prepared from 0.5 wt% polyethylene glycol-modified polydopamine-doped silica@polystyrene bifacial nanoparticles at different oil phase mass fractions.

[0024] Figure 7 Droplet size distribution of JNPs PE emulsion prepared from polydopamine-doped silica@polystyrene double-sided nanoparticles modified with polyethylene glycol.

[0025] Figure 8 (a) Turbiscan stability index, (b) steady-state viscosity curve, and (c) Zeta potential plot of phenyl ether tebuconazole Pickering emulsion JNPs PE prepared under conditions of fixed oil-water ratio (ωo=0.4) and different concentrations of polyethylene glycol-modified polydopamine-doped silica@polystyrene double-sided nanoparticles.

[0026] Figure 9 Images of difenoconazole emulsions stabilized at the same concentration (1.2 wt%) by hydrophobic PS NPs (polystyrene nanoparticles), hydrophilic mPEG-P-MSNs@PS NPs (polyethylene glycol-modified polydopamine-doped silica@polystyrene nanoparticles), or nonionic surfactant EL-40, and the corresponding optical microscopy images.

[0027] Figure 10 Macroscopic phenotypic and optical micrographs of polydopamine-doped silica@polystyrene bifacial nanoparticle-stabilized phenyl ether tebuconazole pickering emulsion JNPs PE (ωo=2 / 5) after storage at different temperatures (0, 20, 40 and 60 °C) for 1 day and 15 days.

[0028] Figure 11 Dynamic behavior of diluted difenoconazole-pickerlin emulsion (JNPs PE droplets) on the upper surface of wheat leaves.

[0029] Figure 12 Dynamic behavior of diluted difenoconazole-pickerlin emulsion (JNPs PE) droplets impacting rice, tobacco, and corn leaves.

[0030] Figure 13 Scanning electron micrograph of wheat leaf surface deposits after application of difenoconazole-pickerlin emulsion (JNPs PE).

[0031] Figure 14 The difenoconazole content in wheat leaves before and after simulated rainfall was measured after applying two emulsion dilutions.

[0032] Figure 15 The content of difenoconazole in different tissues of wheat after application of two emulsion dilutions: (a) leaves, (b) stems, (c) roots.

[0033] Figure 16 (a) Images of the antibacterial activity of commercially available difenoconazole aqueous emulsion (DIF-EW) and difenoconazole-pickerlin emulsion (JNPs PE) at different concentrations against Fusarium graminearum after 6 days of treatment. (b) Dose-response curves of the corresponding inhibition rates against Fusarium graminearum after 6 days of treatment with commercially available difenoconazole aqueous emulsion (DIF-EW) and difenoconazole-pickerlin emulsion (JNPs PE) at different concentrations.

[0034] Figure 17 Twenty-four hours after inoculation with Fusarium spore suspension, 12 days after foliar spraying with commercially available difenoconazole emulsion (DIF-EW) and difenoconazole pickerine emulsion (JNPs PE): (a) disease index, (b) disease severity index.

[0035] Figure 18 Twenty-four hours after inoculation with Fusarium graminearum spore suspension, foliar spraying was performed with commercially available difenoconazole emulsion (DIF-EW) and difenoconazole pickerine emulsion (JNPs PE) or water, and wheat plant phenotypic images were obtained 12 days after application.

[0036] Figure 19Dose-response curves of relative survival of HL-7702 cells after treatment with different concentrations of commercially available difenoconazole aqueous emulsion (DIF-EW) and difenoconazole pickerine emulsion (JNPs PE) for 24 hours. Detailed Implementation

[0037] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprising of," etc., will be understood to include the stated components or steps, without excluding other substances or steps.

[0038] In this invention, wt% represents the mass percentage of the component in the total mass of the system.

[0039] In this invention, vol% represents the volume percentage of the component in the total mass of the system.

[0040] The present invention DIF-EW refers to a commercially available difenoconazole water emulsion.

[0041] The present invention refers to DIF-PE, which represents a difenoconazole-pickerlin emulsion.

[0042] This invention TF leaf- stem , the transport factor from leaves to stem.

[0043] This invention TF leaf- stoot , the transport factor from leaves to roots.

[0044] Furthermore, to better illustrate the present invention, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In some embodiments, materials, methods, and means well-known to those skilled in the art are not described in detail in order to highlight the spirit of the invention.

[0045] This invention first provides an amphiphilic bifacial nanoparticle, characterized in that the amphiphilic Janus (bifacial) nanoparticle is mPEG-P-MSNs@PS JNPs (polyethylene glycol-modified polydopamine-doped silica@polystyrene bifacial nanoparticles). The amphiphilic bifacial nanoparticles of this invention, mPEG-P-MSNs@PS JNPs (polyethylene glycol-modified polydopamine-doped silica@polystyrene bifacial nanoparticles), can significantly improve the stability of Pickle emulsions.

[0046] This invention also provides a method for preparing mPEG-P-MSNs@PS JNPs (polyethylene glycol-modified polydopamine-doped silica@polystyrene bifacial nanoparticles), characterized by comprising the following steps:

[0047] Step 1) Preparation of PS (polystyrene) nanoparticles;

[0048] Step 2) Preparation of P-MSNs@PS NPs (polydopamine-doped silica@polystyrene nanoparticles):

[0049] Step 3) Preparation of P-MSNs@PS JNPs (polydopamine-doped silica@polystyrene double-sided nanoparticles);

[0050] Step 4) Preparation of mPEG-P-MSNs@PS JNPs (polyethylene glycol-modified polydopamine-doped silica@polystyrene double-sided nanoparticles).

[0051] Preferably, the preparation of PS (polystyrene) nanoparticles in step one above includes the following steps:

[0052] a) Dissolve sodium dodecyl sulfate in water, then add styrene, sonicate the mixture, and stir to obtain a styrene microemulsion.

[0053] b) Add the styrene microemulsion obtained in step a) and potassium persulfate to the reaction vessel and react. After the reaction is complete, wash the product with water to obtain PS nanoparticles.

[0054] Preferably, step two above (P-MSNs@PS NPs, polydopamine-doped silica@polystyrene nanoparticles) includes the following steps:

[0055] c) Stir the polystyrene nanoparticles, hexadecyltrimethylammonium bromide, ethanol, water and ammonia at 25-50°C to ensure the system is fully mixed and homogeneous;

[0056] d) Slowly add tetraethoxysilane and dopamine hydrochloride to the mixture obtained in step c), and react at 20-40℃ for 1-5 h to obtain P-MSNs@PS NPs (polydopamine-doped silica@polystyrene nanoparticles).

[0057] Preferably, the preparation of P-MSNs@PS JNPs (polydopamine-doped silica@polystyrene double-sided nanoparticles) in step three above includes the following steps:

[0058] e) P-MSNs@PS NPs (polydopamine-doped silica@polystyrene nanoparticles) were dispersed in a tetrahydrofuran aqueous solution containing sodium dodecyl sulfate and stirred. Ethanol was then added to inhibit further expansion of the polystyrene. After standing, the mixture was centrifuged and washed with deionized water and ethanol. Preferably, the tetrahydrofuran aqueous solution was 40% (vol%), and the stirring time was 6 h. The study found that the volume ratio of the tetrahydrofuran aqueous solution and the stirring time affected the morphology of P-MSNs@PS JNPs (polydopamine-doped silica@polystyrene bifacial nanoparticles).

[0059] g) Disperse the particles obtained in step e) in an ethanol solution of ammonium nitrate and reflux at 40-80°C for 1-8 hours to remove hexadecyltrimethylammonium bromide.

[0060] Preferably, the preparation of mPEG-P-MSNs@PS JNPs (polyethylene glycol-modified polydopamine-doped silica@polystyrene double-sided nanoparticles) in step four above includes the following steps;

[0061] h) P-MSNs@PS NPs were dispersed in an ethanol solution containing 3-aminopropyltrimethoxysilane, refluxed, and then washed with anhydrous ethanol to obtain P-MSNs@PS NPs with amino functionalized surfaces.

[0062] i) Stir the particulate dispersion obtained in step h) in an aqueous solution of tetrahydrofuran containing sodium dodecyl sulfate, then add ethanol to inhibit further expansion of polystyrene, let stand, centrifuge, and wash with deionized water and ethanol.

[0063] j) Disperse the particles obtained in step i) in an ethanol solution of ammonium nitrate and reflux at 40-80°C for 1-8 hours to remove hexadecyltrimethylammonium bromide.

[0064] k) The particles obtained in step j) are dispersed in a weakly alkaline buffer solution containing ethanol, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide and methoxy-polyethylene glycol-carboxyl (mPEG-COOH) are added and stirred. The amine groups on the polydopamine-doped silica (P-MSNs) hemispheres are coupled with the carboxyl groups of the methoxy-polyethylene glycol-carboxyl group. Finally, the particles are washed with water and ethanol in sequence to obtain polyethylene glycol-modified P-MSNs@PS JNPs (mPEG-P-MSNs@PS JNPs).

[0065] This invention also provides a Pickering emulsion comprising a pesticide, mPEG-P-MSNs@PS JNPs (polyethylene glycol-modified polydopamine-doped silica@polystyrene double-sided nanoparticles), and a solvent, wherein the solvent is water and / or an organic solvent. Preferably, the pesticide is difenoconazole. Preferably, the content of mPEG-P-MSNs@PS JNPs (polyethylene glycol-modified polydopamine-doped silica@polystyrene double-sided nanoparticles) in the above-mentioned Pickering emulsion is 0.1-10 wt%, preferably 0.3-2 wt%, more preferably 0.3 wt%, 0.5 wt%, 0.7 wt%, 0.9 wt%, 1.2 wt%, and most preferably 1.2 wt%. (wt% represents the mass percentage of the component in the total mass of the system). Studies have found that the amount of mPEG-P-MSNs@PSJNPs (polyethylene glycol-modified polydopamine-doped silica@polystyrene bi-sided nanoparticles) added affects the quality of Pickering emulsions.

[0066] This invention also provides an application of the Pickering emulsion of this invention in the prevention and control of plant diseases. The plant disease in question is wheat stem rot.

[0067] The present invention will be further described below with reference to the embodiments and accompanying drawings. Raw materials not specifically mentioned in the embodiments can be obtained by purchasing them from the market.

[0068] Sodium dodecyl sulfate (SDS, ≥99.0%) and Nile red (95%) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0069] Ammonia water (NH3·H2O, 28 wt%) and anhydrous ethanol (EtOH) were purchased from Zhiyuan Chemical Reagent Co., Ltd.

[0070] N-(2-hydroxyethyl)piperazine-N′-(2-ethanesulfonic acid) (HEPES) was purchased from Beijing Coolplay Technology Co., Ltd.

[0071] Solvent oil No. 200 (S-200) was purchased from Jiangsu Hualun Chemical Co., Ltd.

[0072] The technical grade difenoconazole (DIF, 96%) was purchased from Shandong Dongtai Agrochemical Co., Ltd.

[0073] Potassium persulfate (KPS, ≥99.0%), anhydrous calcium chloride (CaCl2), anhydrous magnesium sulfate (MgSO4), and anhydrous sodium chloride (NaCl) were purchased from Sinopharm Chemical Reagent Co., Ltd.

[0074] Cleanert C18 adsorbent and Cleanert PSA adsorbent were purchased from Tianjin Bona Aier Technology Co., Ltd.

[0075] Polyoxyethylene castor oil (EL-40) was purchased from Xingtai Yancheng Chemical Additives Co., Ltd.

[0076] The 40% difenoconazole water emulsion was purchased from Shandong Heyi Biotechnology Co., Ltd.

[0077] The size and microstructure of nanoparticles and wheat leaf surfaces were observed using a scanning electron microscope (SEM, SU 8010, Hitachi, Japan) at an accelerating voltage of 10 kV.

[0078] The morphology and internal microstructure of the nanoparticles were characterized by transmission electron microscopy (TEM, JEM-1400, JEOL, Japan), and the spatial distribution of elements in the sample was analyzed by combining the accompanying energy-dispersive X-ray spectroscopy module.

[0079] The pore structure parameters of nanoparticles were determined using a fully automated specific surface area and pore size analyzer (ASAP 2460, Micromeritics, USA). The specific surface area was calculated based on the Brunauer–Emmett–Teller (BET) model, and the pore size distribution was obtained using the Barrett–Joyner–Halenda (BJH) method.

[0080] The hydrated particle size and polydispersity index (PDI) of nanoparticles were determined using a BeNano 180 zeta and a particle size analyzer (Bettersize BT-9300H, China).

[0081] The elemental composition and chemical bonding state of the sample surface were analyzed using X-ray photoelectron spectroscopy (XPS, K-Alpha, Thermo Scientific, USA).

[0082] Fourier transform infrared spectroscopy (FTIR, Nicolet 6700, Thermo Scientific, USA) was used to analyze the functional group characteristics of the samples, with the scan wavenumber range set to 400–4000 cm⁻¹. −1 .

[0083] Example 1 Preparation of polystyrene nanoparticles (PS NPs)

[0084] 40 mg of sodium dodecyl sulfate was dissolved in 20 g of water, and then 1.5 g of styrene was added. The mixture was sonicated for 5 min and stirred for 40 min to obtain a styrene microemulsion. The styrene microemulsion and 40 mg of potassium persulfate were then added to a three-necked flask and reacted at 80 °C under N2 (nitrogen) for 10 h. After the reaction was completed, the product was washed three times with water to obtain polystyrene nanoparticles.

[0085] Example 2: Preparation of polydopamine-doped silica@polystyrene nanoparticles (P-MSNs@PS NPs):

[0086] 1.05 ml of polystyrene nanoparticles (PS NPs) (50 mg / ml), 0.58 g of cetyltrimethylammonium bromide, 19.65 mL of ethanol, 51.55 mL of water, and 0.45 mL of ammonia were stirred at 30 °C for 30 min to ensure thorough mixing. Then, 450 μL of tetraethoxysilane and 30 mg of dopamine hydrochloride were slowly added to the mixture, and the reaction was carried out at 30 °C for 2 h, thereby forming a polydopamine-doped silica shell on the surface of the PS NPs. The resulting polydopamine-doped silica@polystyrene nanoparticles (P-MSNs@PS NPs) were washed three times with ethanol.

[0087] Example 3 Preparation of polydopamine-doped silica@polystyrene bifacial nanoparticles (P-MSNs@PS JNPs)

[0088] 150 mg of polydopamine-doped silica@polystyrene nanoparticles (P-MSNs@PS NPs) were dispersed in 100 mL of a 35% (vol%) tetrahydrofuran aqueous solution containing 1.8 g sodium dodecyl sulfate. The mixture was stirred at 360 rpm for 3 hours, followed by the addition of 200 mL of ethanol to inhibit further expansion of the polystyrene. After standing for 30 min, the mixture was centrifuged and washed three times with deionized water and ethanol. The expansion efficiency of the polystyrene was observed. By selecting appropriate tetrahydrofuran content and stirring time, snowman-shaped bifacial nanoparticles, namely polydopamine-doped silica@polystyrene bifacial nanoparticles (P-MSNs@PS JNPs), could be obtained. These particles were then dispersed in 20 mg / mL... -1 The ammonium nitrate was refluxed at 60°C for 4 hours in an ethanol solution to remove hexadecyltrimethylammonium bromide. This process was repeated three times to ensure complete extraction of hexadecyltrimethylammonium bromide.

[0089] Example 4-11 Preparation of polydopamine-doped silica@polystyrene bifacial nanoparticles (P-MSNs@PS JNPs)

[0090] The preparation methods of Examples 4-11 are the same as those of Example 3, except that the concentration of tetrahydrofuran aqueous solution and the stirring time are adjusted.

[0091] Table 1 Effect of changes in reaction conditions on the products

[0092]

[0093] Example 12 Preparation of polyethylene glycol-modified polydopamine-doped silica@polystyrene bifacial nanoparticles (mPEG-P-MSNs@PS JNPs)

[0094] 600 mg of polydopamine-doped silica@polystyrene nanoparticles (P-MSNs@PS NPs) were dispersed in 240 mL of an ethanol solution containing 2% (vol%) 3-aminopropyltrimethoxysilane, refluxed at 60 °C for 12 h, and washed three times with anhydrous ethanol to obtain P-MSNs@PS NPs with amino functionalized surfaces. The amino functionalized P-MSNs@PS NPs were then dispersed in 100 mL of a 40% (vol%) tetrahydrofuran aqueous solution containing 1.8 g sodium dodecyl sulfate, stirred at 360 rpm for 6 h, followed by the addition of 200 mL of ethanol to inhibit further expansion of the polystyrene. After standing for 30 min, the mixture was centrifuged and washed three times with deionized water and ethanol to obtain snowman-shaped double-sided nanoparticles, namely polydopamine-doped silica@polystyrene double-sided nanoparticles (P-MSNs@PS JNPs). These bifacial nanoparticles were then dispersed in 20 mg mL -1 The ammonium nitrate was refluxed at 60°C for 4 h in an ethanol solution to remove hexadecyltrimethylammonium bromide. This process was repeated three times to ensure complete extraction of hexadecyltrimethylammonium bromide. The resulting particles were further dispersed in a weakly alkaline buffer solution containing ethanol, and 124.6 mg of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, 74.8 mg of N-hydroxysuccinimide, and 500 mg of methoxy-polyethylene glycol-carboxyl (mPEG-COOH) were added. The mixture was stirred for 24 h, allowing the amine groups on the polydopamine-doped silica (P-MSNs) hemispheres to couple with the carboxyl groups of the methoxy-polyethylene glycol-carboxyl group. Finally, the particles were washed sequentially with water and ethanol to obtain polyethylene glycol-modified polydopamine-doped silica@polystyrene bifacial nanoparticles (mPEG-P-MSNs@PS JNPs).

[0095] Example 13 Preparation of polyethylene glycol-modified polydopamine-doped silica@polystyrene nanoparticles (mPEG-P-MSNs@PSs NPs)

[0096] 200 mg of polydopamine-doped silica@polystyrene bifacial nanoparticles (P-MSNs@PS NPs) were dispersed in 240 mL of an ethanol solution containing 2% (vol%) 3-aminopropyltrimethoxysilane, refluxed at 60 °C for 12 h, and washed three times with anhydrous ethanol to obtain polydopamine-doped silica@polystyrene bifacial nanoparticles with amino functionalized surfaces. These particles were then dispersed in 20 mg / mL... -1 The ammonium nitrate was refluxed at 60°C for 4 hours in an ethanol solution to remove hexadecyltrimethylammonium bromide. This process was repeated three times to ensure complete extraction of hexadecyltrimethylammonium bromide. The obtained particles were further dispersed in a weakly alkaline buffer solution containing ethanol, and 124.6 mg of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, 74.8 mg of N-hydroxysuccinimide, and 500 mg of methoxy-polyethylene glycol-carboxyl (mPEG-COOH) were added. The mixture was stirred for 24 h, and the amine groups on the polydopamine-doped silica (P-MSNs) were coupled with the carboxyl groups of the methoxy-polyethylene glycol-carboxyl group. Finally, the particles were washed with water and ethanol in sequence to obtain isotropic polyethylene glycol-modified polydopamine-doped silica (mPEG-P-MSNs) shell uniformly coated with polystyrene nanoparticles (PS NPs), namely polyethylene glycol-modified polydopamine-doped silica@polystyrene nanoparticles (mPEG-P-MSNs@PS NPs).

[0097] Example 14 Preparation of mPEG-P-MSNs@PS JNPs-stabilized difenoconazole-pickerlin emulsion

[0098] Using deionized water containing 25 mg of polyethylene glycol-modified polydopamine-doped silica@polystyrene nanoparticles (mPEG-P-MSNs@PS NPs) as the aqueous phase and S-200, an aromatic solvent containing difenoconazole, as the oil phase, the contents of difenoconazole (15 wt%) and polyethylene glycol-modified polydopamine-doped silica@polystyrene nanoparticles (mPEG-P-MSNs@PS NPs) (0.5 wt%) were fixed. The mass ratio of oil phase to water phase was 2:3. The water / oil mixture was sheared for 3 min at speed 5 using a homogenizer (T 10basic Ultra turrax, IKA, Germany) to obtain a difenoconazole Pickering emulsion (JNPs PE) prepared from polyethylene glycol-modified polydopamine-doped silica@polystyrene nanoparticles (mPEG-P-MSNs@PS NPs).

[0099] Examples 15-22 Preparation of polyethylene glycol-modified polydopamine-doped silica@polystyrene nanoparticles (mPEG-P-MSNs@PS NPs) stabilized phenoxymethyl azole pickerling emulsion

[0100] The preparation methods of Examples 15-22 are the same as those of Example 14, except that the mass ratio of oil phase / water phase and the content of polyethylene glycol modified polydopamine-doped silica@polystyrene nanoparticles (mPEG-P-MSNs@PS NPs) are adjusted.

[0101] Table 2. Adjusting parameters for Pickering emulsion

[0102]

[0103] Example 23 Preparation of polystyrene nanoparticle (PS NPs) stabilized phenyl ether tebuconazole pickering emulsion

[0104] Using 3 g of deionized water containing 60 mg of polystyrene nanoparticles (PS NPs) as the aqueous phase and 2 g of S-200 aromatic solvent containing difenoconazole as the oil phase, with fixed difenoconazole content (15 wt%) and PS NPs content (1.2 wt%), and an oil / water phase mass ratio of 2:3, the water / oil mixture was sheared for 3 min at speed 5 using a homogenizer (T 10 basic Ultra turrax, IKA, Germany) to obtain a difenoconazole Pickering emulsion prepared from PS NPs.

[0105] Example 24 Preparation of a polyethylene glycol-modified polydopamine-doped silica@polystyrene nanoparticle (mPEG-P-MSNs@PS NPs) stabilized benzyl ether benzoyl ether pickerel emulsion

[0106] Using 3 g of deionized water containing 60 mg of polyethylene glycol-modified polydopamine-doped silica@polystyrene nanoparticles (mPEG-P-MSNs@PS NPs) as the aqueous phase and 2 g of S-200 aromatic solvent containing difenoconazole as the oil phase, with fixed difenoconazole content (15 wt%) and polyethylene glycol-modified polydopamine-doped silica@polystyrene nanoparticles (mPEG-P-MSNs@PS NPs) content (1.2 wt%), the oil / water phase mass ratio was 2:3. The water / oil mixture was sheared for 3 min at speed 5 using a homogenizer (T10 basic Ultra turrax, IKA, Germany) to obtain a difenoconazole Pickering emulsion prepared from polyethylene glycol-modified polydopamine-doped silica@polystyrene nanoparticles (mPEG-P-MSNs@PS NPs).

[0107] Example 25 Preparation of EL-40 stabilized difenoconazole-pickerlin emulsion

[0108] Using 3 g of deionized water containing 60 mg EL-40 as the aqueous phase and 2 g of S-200, an aromatic solvent containing difenoconazole, as the oil phase, with fixed difenoconazole content (15 wt%) and EL-40 content (1.2 wt%), and an oil / water phase mass ratio of 2:3, the water / oil mixture was sheared for 3 min at speed 5 using a homogenizer (T 10 basic Ultra turrax, IKA, Germany) to obtain a difenoconazole-pickerlin emulsion prepared with EL-40.

[0109] Test example:

[0110] 1. Morphological examination of polydopamine-doped silica@polystyrene double-sided nanoparticles (P-MSNs@PS JNPs):

[0111] The morphology of the polydopamine-doped silica@polystyrene nanoparticles (P-MSNs@PSNPs) obtained in Example 2 was controlled under the conditions of tetrahydrofuran concentration and stirring time as in Examples 3-11. The results were observed using scanning electron microscopy. Figure 1 It is evident that the swelling efficiency of the PS (polystyrene) core increases with the increase of treatment time or concentration of polydopamine-doped silica@polystyrene nanoparticles (P-MSNs@PS NPs) in tetrahydrofuran aqueous solution. However, low concentrations of tetrahydrofuran and shorter treatment times result in ineffective escape of the PS core or a small volume after escape, while high concentrations of tetrahydrofuran and longer treatment times lead to excessive expansion of the PS core after escape. Therefore, the tetrahydrofuran concentration and stirring time have a significant impact on the swelling efficiency of PS (polystyrene). Among them, the highest polystyrene core dissolution rate and the best swelling effect were obtained under the conditions of 40 vol% tetrahydrofuran and 6 h treatment time. The snowman-shaped polydopamine-doped silica@polystyrene bifacial nanoparticles (P-MSNs@PS JNPs) with relatively uniform morphology were obtained. This ensures that the bifacial nanoparticles have both hydrophobic polystyrene (PS) and hydrophilic polydopamine-doped silica (P-MSNs) parts. The uniformity of morphology can effectively ensure that the amphiphilic effect of the bifacial nanoparticles is basically consistent.

[0112] The polydopamine-doped silica@polystyrene bifacial nanoparticles (P-MSNs@PSJNPs) prepared in Example 7 were shown by scanning electron microscopy and transmission electron microscopy to have a connected, contrast-differential biphase asymmetric morphology. Figure 2 a and Figure 2b). Elemental distribution analysis results from transmission electron microscopy and energy-dispersive X-ray spectroscopy show that ( Figure 2 d), the N, Si and O signals representing the polydopamine-doped silica (P-MSNs) shell are limited to only one side of the particle, while the C signal representing the polystyrene (PS) portion is distributed throughout the particle, confirming that the Janus (two-sided) structure of Example 7 originates from the directional outward escape and expansion of the PS core through a single gap in the shell, rather than the random aggregation of the two types of particles.

[0113] The morphology and particle size of the polyethylene glycol-modified polydopamine-doped silica@polystyrene bifaceted nanoparticles (mPEG-P-MSNs@PS JNPs) synthesized under the conditions of Example 12 were characterized by scanning electron microscopy and a particle size analyzer. The results showed that there were no significant changes in particle size and morphology, but... Figure 2 Scanning electron microscopy (SEM) images show that its surface has become rough. According to... Figure 3 The particle size distribution shows that the amphiphilic polyethylene glycol-modified polydopamine-doped silica@polystyrene bifacial nanoparticles (mPEG-P-MSNs@PS JNPs) are snowman-shaped bifacial nanoparticles composed of a 43.63±0.47 nm hydrophobic polystyrene portion and a 97.43±0.48 nm polyethylene glycol-modified polydopamine-doped silica portion, with relatively uniform particle size.

[0114] 2. Stability Test

[0115] The difenoconazole-pickerlin emulsions (JNPs PE) prepared in Examples 14-18 using the oil / aqueous phase were observed using an optical microscope, and the results are as follows: Figure 4 The results show that when the oil phase mass fraction is lower than the water phase mass fraction (ωo < ωw), the system forms regularly shaped oil-in-water dispersed phase droplets. As ωo increases, the number of particles available for interfacial coverage in the continuous phase per unit volume decreases, while the probability of oil droplet aggregation increases, leading to a gradual increase in the average droplet size. When ωo > ωw, the system undergoes a phase inversion and forms a water-in-oil emulsion. This transformation is related to the continuous phase transition caused by the change in phase volume composition ratio, and also reflects the synergistic regulatory effect of particle wettability and interfacial coverage on emulsion type. Figure 5The phenotypic graphs showed that all formulations maintained good macroscopic stability during a 3-month storage period. With increasing ω, the degree of water separation in the difenoconazole-pickerlin emulsion (JNPs PE) decreased. This trend may be related to non-covalent interactions such as π–π stacking and hydrogen bonding between aromatic molecules in the oil phase and polyethylene glycol-modified polydopamine-doped silica@polystyrene bifacial nanoparticles (mPEG-P-MSNs@PS JNPs). The shear viscosity of the difenoconazole-pickerlin emulsion (JNPs PE) prepared in 14–19 was tested using a rheometer (MCR 502, Anton Paar, Austria). At a constant temperature of 25°C, 1 ml of sample was tested using PP25 parallel plates (25 mm diameter, 1 mm gap) at shear rates ranging from 0.1 to 100 s⁻¹. The results showed that the viscosity of the difenoconazole-pickerlin emulsion (JNPs PE) increased with increasing oil phase mass fraction. Figure 6 This indicates that the non-covalent interaction and the increase in system viscosity jointly reduce the droplet migration rate, thereby weakening gravitational stratification and dispersed phase droplet collisions. The above results show that emulsion stability increases with increasing oil phase mass fraction. When ωo is greater than 25%, no water separation occurs, and when ωo exceeds 50%, the formulation reverses from an oil-in-water type to an oil-in-water type. Given that the subsequent pesticide delivery system needs to consider the amount of oil phase, environmental impact, and emulsion stability, under the premise of emulsion stability, a difenoconazole-pickerlin emulsion (JNPs PE) with a lower ωo content was selected for subsequent experiments.

[0116] The difenoconazole-pickerlin emulsions (JNPs-PE) prepared in Examples 14 and 20-22 were observed using an optical microscope, and the results are as follows: Figure 7 The results show that as the particle concentration increases, the average particle size of the dispersed phase droplets decreases, and the particle size distribution gradually narrows. When the particle content is 1.2 wt%, the average minimum particle size of the dispersed phase droplets is approximately 2.39 μm. This is because a higher particle concentration can increase the coverage rate and degree of particles at the nascent oil / water phase interface, inhibiting droplet aggregation after formation, thus facilitating the acquisition of emulsions with smaller particle sizes and more uniform distribution.

[0117] The colloidal stability of the difenoconazole-pickerlin emulsions (JNPs PE) prepared in Examples 14 and 20-23 was evaluated using a Turbiscan Lab Tower (Formulation, France). Samples were injected into vials, and the detector scanned along the glass cylinder within the sample from the bottom (0 mm) to the top (approximately 50 mm) at 25°C every 500 s for 5 hours. The Turbiscan Stability Index (TSI) was calculated by monitoring the backscattered light signal (BS) and transmittance (T) of the sample to reflect the stability of the sample over a short period. A smaller slope in the stability kinetic curve indicates better sample stability. The formula for calculating the TSI is as follows:

[0118]

[0119] Where n is the number of scans, Xi is the average backscatter intensity measured per minute, and X BS This is the average value for all Xi. The results are as follows: Figure 8 The results showed that the TSI of emulsions with different particle contents was less than 1 and further decreased with increasing particle concentration, indicating that the systems with different mPEG-P-MSNs@PS JNPs contents all had good storage stability, and the stability increased with increasing particle content.

[0120] The shear viscosity of the difenoconazole-pickerlin emulsions (JNPs PE) prepared in 14 and 20-22 was tested using a rheometer (MCR 502, Anton Paar, Austria). The viscosity was measured in 1 ml samples at shear rates ranging from 0.1 to 100 s⁻¹ under isothermal conditions of 25°C using parallel PP25 plates (25 mm diameter, 1 mm gap). The results are as follows: Figure 8 As shown in b, the viscosity of the system increases with the increase of mPEG-P-MSNs@PS JNPs content. Simultaneously, particle size analysis shows that the absolute value of the Zeta potential gradually increases with the increase of mPEG-P-MSNs@PS JNPs content. Figure 8 c) The above results collectively indicate that a dense nanoparticle spatial network is formed between the free mPEG-P-MSNs@PS JNPs in the aqueous phase and the particle layer at the oil / aqueous phase interface. The non-covalent interactions such as hydrogen bonds and electrostatic repulsion between particles are enhanced, which inhibits droplet migration and aggregation, effectively prevents gravitational stratification and phase separation, and further enhances the stability of the emulsion.

[0121] Following the methods of Examples 23-25, emulsions were prepared using the same amount (1.2 wt%) of hydrophobic PS NPs (prepared in Example 1), hydrophilic mPEG-P-MSNs@PS NPs (prepared in Example 12), and nonionic surfactant EL-40. Figure 9 Isotropic PS NPs and mPEG-P-MSNs@PS NPs cannot be stably anchored at the oil / aqueous interface, and both emulsions undergo phase separation within a short time. Although EL-40 can adhere to the oil / aqueous interface to form spherical dispersed droplets, it cannot suppress Austronstein ripening of the droplets, leading to a decrease in the number of small-diameter droplets, a significant increase in the average particle size, and gravitational stratification of the emulsion. In contrast, the mPEG-P-MSNs@PS JNPs-stable emulsion (JNPs PE) exhibits excellent storage stability in the range of 0–60°C. Figure 10 ).

[0122] 3. The effect of JNPs PE system on leaf droplet bouncing effect

[0123] The JNPs PE prepared in Examples 14 and 20-22 were diluted 750-fold to the recommended field dosage (8 g / mu), with commercially available difenoconazole emulsion (DIF-EW) diluted to the same concentration as a control group. The dynamic process of droplet impact on wheat seedling leaves was recorded using a high-speed camera (FASTCAMMini UX100, Photron, Japan) at a frame rate of 8000 frames / second and a shutter speed of 1 / 20000 second. The syringe needle was positioned vertically 35 cm above the upper epidermis of the wheat leaf to ensure that droplets from different formulations were released from the same height and with the same initial velocity, guaranteeing a consistent impact velocity. The impact behavior of the JNPs PE prepared in Example 22 (1.2 wt% mPEG-P-MSNs@PS JNPs) diluted 750-fold on rice, tobacco, and maize leaves was observed using the same parameters. The results showed that higher mPEG-P-MSNs@PS JNPs content significantly suppressed the rebound height and fragmentation of spray droplets, and enabled droplets to reach stable spreading more quickly. This may be due to enhanced interactions between particles and between particles and the aqueous phase, which dissipates some of the impact kinetic energy through viscous dissipation, weakening the capillary driving force and inertial forces that dominate droplet retraction, as well as behaviors such as fragmentation, splashing, and even rebound. Figure 11 When the mPEG-P-MSNs@PS JNPs content is higher than 0.9wt%, it not only reduces the tendency of spray droplets to retract, break, and detach from the leaf surface, but also promotes the droplets to transition from a dynamic impact state to a stable spreading state more quickly. This allows the JNPs PE dilution to remain on the leaves of wheat, rice, tobacco, and corn in the form of a liquid film or droplets, demonstrating good versatility. Figure 12 ).

[0124] 4. Determination of the effects of JNPs PE system on leaf deposition and adhesion.

[0125] To analyze the retention of the formulation on the target leaf surface, a rain simulation experiment was conducted. At the wheat seedling stage, diluted solutions of JNPs PE and DIF-EW prepared in Example 22 (active ingredient diluted to twice the field recommended high dose, 400 mg / L) were applied at room temperature. One hour after application, wheat leaves were collected and fixed on glass slides at a 30° angle. The leaves were vertically rinsed with deionized water from a height of 10 cm at a flow rate of 5 mL / min for 30 min to simulate rainfall. Unrinsed leaves served as a control for initial deposition. The content of difenoconazole in rinsed and unrinsed leaves was determined using high-performance liquid chromatography-mass spectrometry (HPLC-MS / MS, QTRAP 5500, AB SCIEX, USA).

[0126] Detection by high performance liquid chromatography-tandem mass spectrometry showed that, under the same application conditions, the deposition amount of JNPs PE prepared in Example 22 on wheat leaves was 42.72% higher than that of the commercially available difenoconazole water-in-oil emulsion control group DIF-EW. Figure 14 As the water content in the pesticide solution deposited on the wheat leaves gradually decreases, the particle layer maintaining the stability of the oil / water phase interface gradually becomes unstable. When the water evaporates, the mPEG-P-MSNs@PS JNPs at the oil / water phase interface can no longer be anchored. They adhere to or embed together with the mPEG-P-MSNs@PS JNPs that were originally free in the aqueous phase, forming a drug film adhesion layer on the wheat leaf surface with its lamellar morphology of epidermal wax and epidermal hairs. Figure 13 This resulted in JNPs PE exhibiting a 64.90% improvement in rainwater erosion resistance compared to the control group DIF-EW. Figure 14 The improved deposition and retention properties of the drug solution provide a good interfacial basis for subsequent foliar absorption and in vivo transport.

[0127] 5. Effect of JNPs PE system on the transport of difenoconazole in wheat.

[0128] Diluted solutions of JNPs PE and DIF-EW prepared in Example 22 (active ingredient diluted to twice the field recommended high dose, 400 mg / L) were applied to wheat seedlings at room temperature. Wheat leaves, stems, and roots were collected at 0.5, 1, 3, 6, and 10 days after application. The content of difenoconazole in leaves, stems, and roots was determined by high-performance liquid chromatography-tandem mass spectrometry. The results showed that the JNPs PE treatment group and the DIF-EW control group exhibited similar spatiotemporal dose distribution patterns over 10 days. The difenoconazole content in leaves decreased over time, possibly due to translocation to the stem and intra-tissue metabolic degradation. In the stem, the content initially increased and then decreased under the dynamic balance of continuous input and translocation / degradation to the roots, while in the roots, it showed a continuous accumulation trend. However, the difenoconazole content in all parts of wheat in the JNPs PE group was significantly higher than that in the DIF-EW group at different time points. Figure 15 The translocation assessment of both revealed that the translocation factor (TF) from leaves to stems was higher in the JNPs PE treatment group. leaf- stem (0.20-0.87) and DIF-EW group (TF leaf- stem The values ​​were similar (0.18–0.83), but the translocation factor (TF) from leaves to roots in the JNPs PE treatment group was significantly higher. leaf- stoot The F100 (0.012–0.11) level was significantly higher than that of the DIF-EW group (TF). leaf- stoot (0.0074–0.055) Figure 15 This phenomenon further explains that the increased accumulation of difenoconazole in the rhizome and the improved efficiency of translocation to the roots may be mainly due to JNPs PE improving leaf deposition and transleaf translocation, rather than changing the physicochemical properties of difenoconazole.

[0129] 6. Effects of the JNPs PE system on the control of wheat stem rot

[0130] Using a commercially available water-in-oil emulsion (DIF-EW) with similar physicochemical properties as a control, *Fusarium graminearum* was selected as the test bacterium, and the antibacterial activity of JNPs PE was evaluated using the PDA plate method. Different concentrations of JNPs PE and DIF-EW prepared in Example 22 were added to melted solid PDA medium to prepare PDA medium with concentration gradients of difenoconazole of 0.1 mg / L, 0.2 mg / L, 0.4 mg / L, 0.8 mg / L, and 1.6 mg / L. Sterile water was used as the control group instead of the emulsion-treated PDA medium. Mycelial cakes were obtained using a 5 mm punch and inoculated into the center of solidified PDA plates. The plates were sealed with sealing film and inverted in a 25°C incubator for 6 days. Each treatment was repeated 5 times. Finally, the colony diameter (S) was measured using the cross-cross method. A virulence regression equation, EC50 value, and correlation coefficient R² were fitted based on the concentration gradient and mycelial growth inhibition rate. The inhibition rate (IR) was calculated using the following formula:

[0131]

[0132] Where d1 (mm) is the colony diameter of the control group, d2 (mm) is the colony diameter of the treatment group, and d0 (mm) is the inner diameter of the punch. The smaller the EC50 value, the stronger the antifungal activity of the formulation.

[0133] The results are as follows Figure 16 As shown in a, 16b, and Table 1, the EC50 value of JNPs PE (0.4638 mg / L) is similar to that of DIF-EW (0.4765 mg / L), indicating that the introduction of JNPs did not significantly alter the inherent virulence of DIF against the pathogen. Therefore, the difference in subsequent efficacy can mainly be attributed to the regulation of leaf deposition by the formulation, rather than changes in the original antibacterial ability of the active ingredient.

[0134] To test the in vivo control effect of JNPs PE, wheat seedlings were inoculated with a spore suspension (2×10⁻⁶). 5 Twenty-four hours after spraying (sporangia / mL), the control effects of different formulations on wheat stem rot were observed by foliar spraying with diluted JNPs PE and DIF-EW solutions prepared in Example 22 (diluted to the recommended field dose, 200 mg / L). All wheat plants were cultured in a greenhouse at 25°C, 50-60% relative humidity, and a light / dark cycle of 14 h / 10 h. Each treatment was repeated four times. The susceptibility of each wheat plant was statistically analyzed 12 days after spraying. The disease index and control efficacy were evaluated using the following formula:

[0135]

[0136]

[0137] The results showed that the JNPs PE group exhibited effective disease suppression, with a disease index of 16.95, significantly lower than that of the DIF-EW control group (31.07). Figure 17 a). The JNPs PE group showed an approximately 26.30% higher prevention and control effect compared to the DIF-EW control group ( Figure 17 b and Figure 18 ).

[0138] Considering the potential inhalation exposure risk from droplets formed during foliar spraying, the CCK-8 assay was used to evaluate the cytotoxicity of JNPs PE prepared in Example 22 against normal human hepatocytes HL-7702 cells. HL-7702 cells in logarithmic growth phase were sprayed at 8 × 10⁻⁶ cells / year. 3Cells were seeded in 96-well plates and incubated overnight at 37°C with 5% CO2 in a WCI-180, Wiggens, China until adherence. Subsequently, cells were treated with gradient concentrations of JNPs PE and DIF EW (2.34375, 4.6875, 9.375, 18.75, 37.5, 75, 150 ppm), with complete culture medium as a negative control, and incubated for another 24 h. After treatment, the supernatant was discarded, and cells were gently washed three times with PBS. 100 μL of complete culture medium containing 10% CCK-8 reagent was added to each well, and the cells were incubated at 37°C with 5% CO2 for 2 h. The absorbance at 450 nm was measured using a microplate reader (SPARK 10M, Tecan, Switzerland).

[0139] The results showed that the half-maximal inhibitory concentration (IC50) of JNPs PE was higher than 150 mg / L. −1 It was significantly higher than DIFEW's 57.75 mg L. −1 This indicates that JNPs PE exhibited low cytotoxicity in this in vitro model. Figure 19 (and Table 2).

[0140] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An amphiphilic bifacial nanoparticle, characterized in that, The amphiphilic double-sided nanoparticles are polyethylene glycol-modified polydopamine-doped silica@polystyrene double-sided nanoparticles.

2. A method for preparing polyethylene glycol-modified polydopamine-doped silica@polystyrene bifacial nanoparticles, characterized in that, Includes the following steps: Step 1) Preparation of polystyrene nanoparticles; Step 2) Preparation of polydopamine-doped silica@polystyrene nanoparticles; Step 3) Preparation of polydopamine-doped silica@polystyrene double-sided nanoparticles; Step 4) Preparation of polyethylene glycol-modified polydopamine-doped silica@polystyrene double-sided nanoparticles.

3. The method for preparing polyethylene glycol-modified polydopamine-doped silica@polystyrene bifacial nanoparticles according to claim 2, characterized in that, Step 1) The preparation of polystyrene nanoparticles includes the following steps: a) Dissolve sodium dodecyl sulfate in water, then add styrene, sonicate the mixture, and stir to obtain a styrene microemulsion. b) Add the styrene microemulsion obtained in step a) and potassium persulfate to the reaction vessel and react. After the reaction is complete, wash the product with water to obtain polystyrene nanoparticles.

4. The method for preparing polyethylene glycol-modified polydopamine-doped silica@polystyrene bifacial nanoparticles according to claim 2 or 3, characterized in that, Step 2) The preparation of polydopamine-doped silica@polystyrene nanoparticles includes the following steps: c) Stir the polystyrene nanoparticles, hexadecyltrimethylammonium bromide, ethanol, water and ammonia at 25-50°C to ensure the system is fully mixed and homogeneous; d) Slowly add tetraethoxysilane and dopamine hydrochloride to the mixture obtained in step c), and react at 20-40℃ for 1-5 h to obtain polydopamine-doped silica@polystyrene nanoparticles.

5. The method for preparing polyethylene glycol-modified polydopamine-doped silica@polystyrene bifacial nanoparticles according to claim 4, characterized in that, Step 3) The preparation of polydopamine-doped silica@polystyrene double-sided nanoparticles includes the following steps: e) Disperse polydopamine-doped silica@polystyrene nanoparticles in a tetrahydrofuran aqueous solution containing sodium dodecyl sulfate and stir. Then add ethanol to inhibit further expansion of polystyrene. After standing, centrifuge and wash with deionized water and ethanol. g) Disperse the particles obtained in step e) in an ethanol solution of ammonium nitrate and reflux at 40-80°C for 1-8 hours to remove hexadecyltrimethylammonium bromide.

6. The method for preparing polyethylene glycol-modified polydopamine-doped silica@polystyrene bifacial nanoparticles according to claim 4, characterized in that, Step 4) The preparation of polyethylene glycol-modified polydopamine-doped silica@polystyrene double-sided nanoparticles includes the following steps; h) Polydopamine-doped silica@polystyrene nanoparticles were dispersed in an ethanol solution containing 3-aminopropyltrimethoxysilane, and after reflux reaction, washed with anhydrous ethanol to obtain polydopamine-doped silica@polystyrene nanoparticles with amino functionalized surface. i) Disperse the polydopamine-doped silica@polystyrene nanoparticles with amino functionalized surfaces obtained in step h) in an aqueous solution of tetrahydrofuran containing sodium dodecyl sulfate and stir. Then add ethanol to inhibit further expansion of polystyrene. After standing, centrifuge and wash with deionized water and ethanol to obtain amino functionalized polydopamine-doped silica@polystyrene bi-sided nanoparticles without removal of hexadecyltrimethylammonium bromide. j) Disperse the particles obtained in step i) in an ethanol solution of ammonium nitrate, and reflux at 40-80°C for 1-8 hours to remove hexadecyltrimethylammonium bromide, thereby obtaining polydopamine-doped silica@polystyrene bi-sided nanoparticles with amino functionalization. k) The particles obtained in step j) are dispersed in a weakly alkaline buffer solution containing ethanol, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide and methoxy-polyethylene glycol-carboxyl groups are added. The mixture is stirred, and the amine groups on the polydopamine-doped silica hemispheres are coupled with the carboxyl groups of the methoxy-polyethylene glycol-carboxyl groups. Finally, the mixture is washed with water and ethanol in sequence to obtain polyethylene glycol-modified polydopamine-doped silica@polystyrene bi-sided nanoparticles.

7. A Pickering emulsion, characterized in that, The invention comprises pesticides, polyethylene glycol-modified polydopamine-doped silica@polystyrene double-sided nanoparticles, and a solvent, wherein the solvent is water and solvent oil.

8. The Pickering emulsion according to claim 7, characterized in that, The pesticide in question is difenoconazole.

9. The Pickering emulsion according to claim 7 or 8, characterized in that, The content of the polyethylene glycol-modified polydopamine-doped silica@polystyrene double-sided nanoparticles is 0.1-10 wt%.

10. The use of Pickering emulsion according to any one of claims 7-9 in the prevention and control of plant diseases.

11. The application according to claim 10, characterized in that, The plant disease mentioned is wheat stem base rot.

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