A pollen-like imidacloprid nanopesticide, its preparation method and application

Abstract

This invention discloses a pollen-like imidacloprid nanopesticide, its preparation method, and its application. The preparation method includes: mixing solid silica spheres, water, copper nitrate, and ammonia solution, and then carrying out a hydrothermal reaction at 120-140℃; the mass ratio of the solid silica spheres to ammonia in the ammonia solution is 1:8 to 1:20; rinsing the product in hydrochloric acid to obtain pollen-like, rough-surfaced hollow silica; dissolving sucrose in water to form a sucrose aqueous solution; dissolving imidacloprid in acetone, adding the pollen-like, rough-surfaced hollow silica, stirring, and then rotary evaporating; adding the sucrose aqueous solution and rotary evaporating again. Compared with commercially available imidacloprid water-dispersible particles, the pesticide of this invention has 2.1 times the adhesion ability on pakchoi leaves. Under simulated rainfall conditions, the leaf retention rate of the pollen-like nanopesticide is 4.8 times that of commercially available imidacloprid water-dispersible particles. After 8 hours of UV irradiation, the imidacloprid residue rate of the pesticide of this invention is still as high as 76.8%.

Description

Technical Field

[0001] This invention relates to the field of nanopesticide technology, specifically to a pollen-like imidacloprid nanopesticide, its preparation method, and its application. Background Technology

[0002] In traditional agricultural production, pesticides play an indispensable role in ensuring crop yields and controlling pests and diseases. However, the low utilization rate of pesticides has long been a key problem hindering agricultural development. Statistics show that nearly 90% of traditionally sprayed pesticides ultimately fail to effectively target their intended targets, instead being lost to the environment through droplet bounce, wind drift, rain washout, and photodegradation, leading to serious resource waste and environmental pollution. This low utilization rate not only increases agricultural production costs, but more importantly, pesticide residues pose potential hazards to soil, water sources, and non-target organisms (such as pollinating insects, soil microorganisms, and fish), seriously threatening ecological balance and human health.

[0003] Specifically, traditional pesticide formulations, such as suspension concentrates and wettable powders, often exhibit high surface tension and the hydrophobic nature of leaf surfaces when sprayed onto plant leaves. This causes droplets to spherically form and bounce, reducing pesticide deposition on the leaves. Even if some pesticides adhere to the leaves, insufficient adhesion makes these particles easily washed away by rain or irrigation, further diminishing the duration of efficacy. Furthermore, ultraviolet radiation is a significant factor contributing to pesticide decomposition and inactivation, especially under strong sunlight, where the active ingredients rapidly degrade, shortening their field retention period. These combined issues necessitate higher application rates to achieve the desired effects, undoubtedly increasing the risk of pesticide residues and environmental pollution.

[0004] To overcome the aforementioned shortcomings of traditional pesticide formulations, nanotechnology has been gradually introduced into the field of pesticide formulation in recent years, resulting in various nanopesticide delivery systems. By encapsulating the active ingredients of pesticides in nanocarriers, the dispersibility and adhesion of pesticides on plant surfaces can theoretically be improved, and loss and degradation can be reduced to some extent. However, existing nanopesticide technologies still have significant limitations. For example, silica nanomaterials are widely used as pesticide delivery carriers due to their nanoscale size, high specific surface area, good biocompatibility, and biodegradability. Mesoporous silica structures are advantageous for achieving high pesticide loading capacities, but their actual contact area with leaf surfaces is limited, making it difficult to simultaneously achieve high pesticide loading capacity and strong adhesion. At the same time, under complex field conditions, some nanopesticides tend to release rapidly in a short time, making it difficult to achieve stable and controllable slow-release effects, thus resulting in a limited duration of efficacy. In addition, most nanopesticides also face the problem of poor photostability. Therefore, existing nano-pesticides still struggle to achieve effective synergy among key properties such as UV resistance, slow-release performance, leaf adhesion, and dispersion stability, resulting in limited overall application effects and failing to fully meet the demands of modern agriculture for efficient, long-lasting, and environmentally friendly pesticide formulations. Summary of the Invention

[0005] The technical problem to be solved by this invention is how to improve the UV resistance, rain erosion resistance and slow-release performance of imidacloprid pesticides.

[0006] The present invention solves the above-mentioned technical problems through the following technical means: A method for preparing a pollen-like imidacloprid nanopesticide includes the following steps: S1. A hydrothermal reaction is carried out after mixing solid silica spheres, water, copper nitrate, and ammonia. The mass ratio of solid silica spheres to ammonia in the ammonia solution is 1:8 - 1:20. The hydrothermal reaction temperature is 120-140℃. S2. The product after the hydrothermal reaction of S1 is immersed in hydrochloric acid and acid washed to obtain pollen-like rough hollow silica. S3. Dissolve sucrose in water to form a sucrose aqueous solution; dissolve imidacloprid in acetone, add pollen-like rough-surfaced hollow silica, stir and then rotary evaporate, then add the sucrose aqueous solution, and rotary evaporate to obtain the pollen-like imidacloprid nanopesticide.

[0007] Preferably, in S1, the mass ratio of the solid silica spheres to the ammonia in the ammonia solution is one of 1:8, 1:8.5, 1:8.65, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:19.38, or 1:20.

[0008] Preferably, in S1, solid silica spheres are prepared using the classic Stöber method.

[0009] Preferably, in S1, the mass ratio of solid silica spheres to copper nitrate is 13:17; the volume ratio of solid silica spheres to water is 0.13 g: 20-50 mL; and the volume ratio of solid silica spheres to ammonia is 0.13 g: 5-10 mL.

[0010] Preferably, in S1, the hydrothermal reaction time is 10-36 h.

[0011] Preferably, in step S2, the concentration of hydrochloric acid is 1 mol / L, the pickling temperature is 50°C, and the time is 4 h.

[0012] Preferably, in S3, the mass ratio of sucrose to imidacloprid is 5:6.

[0013] Preferably, in S3, the mass ratio of imidacloprid to pollen-like rough-surfaced hollow silica is 1-2:1-4; more preferably 2:3.

[0014] Preferably, in S3, the ratio of sucrose to water is 50 mg: 0.5 mL; and the ratio of imidacloprid to acetone is 60 mg: 10 mL.

[0015] The present invention also proposes a pollen-like imidacloprid nanopesticide, which is prepared by the aforementioned method for preparing pollen-like imidacloprid nanopesticides.

[0016] Preferably, in the pollen-like imidacloprid nanopesticide, the loading rate of imidacloprid is 22-42%.

[0017] This invention also proposes the application of the aforementioned pollen-like imidacloprid nanopesticide in the control of aphids on Chinese cabbage.

[0018] Pollen grains in nature are renowned for their excellent adhesion and erosion resistance. Their surfaces typically possess micron- or nanometer-scale rough structures, effectively increasing the contact area and friction with target surfaces, thus achieving strong adhesion. This biomimetic design concept provides a new direction for pesticide carrier development. By mimicking the structural characteristics of pollen to construct nanoscale carriers with specific roughness, it is expected to significantly improve pesticide adhesion on leaves and retention rates under rainfall conditions, thereby greatly enhancing pesticide bioavailability and ultimately achieving reduced pesticide application and lowering negative environmental impacts. This innovative approach not only effectively addresses the challenges faced by existing pesticides but also provides a new technological pathway for sustainable agricultural development.

[0019] This invention provides a method for preparing a pollen-like, rough, hollow nanopesticide and the resulting nanopesticide product. The preparation method includes: using silica spheres as templates, controlling the growth of a pollen-like rough structure on the surface through a hydrothermal reaction; then obtaining a pollen-like, rough, hollow silica carrier through acid etching; encapsulating the pesticide active ingredient imidacloprid into the hollow carrier using a modified impregnation method; and adding the adjuvant sucrose to obtain the final nanopesticide formulation. The nanopesticide prepared by this invention possesses the structural characteristics of biomimetic pollen grains. Its rough surface significantly increases the contact area and friction with crop leaves, greatly enhancing the pesticide's leaf adhesion ability and resistance to rain washout. Test results show that, compared with commercially available imidacloprid water-dispersible particles, the pollen-like nanopesticide of this invention has 2.1 times the initial adhesion ability and 4.8 times the leaf retention rate on pakchoi leaves. Meanwhile, due to the protective effect of the hollow carrier, this nano-pesticide exhibits excellent resistance to UV degradation; even after 8 hours of UV irradiation, the imidacloprid retention rate remains as high as 76.8%. This nano-pesticide can achieve better control effects with lower application concentrations, increasing the control rate against aphids on Chinese cabbage by 30.1%. This invention effectively solves the problems of low utilization, easy loss, and easy degradation of traditional pesticides, providing a new technical approach for achieving pesticide reduction and sustainable agriculture. Attached Figure Description

[0020] Figure 1 (a) SEM image and (b) TEM image and energy spectrum of the pollen-like surface rough hollow nanopesticide of the present invention; Figure 2 These are UV resistance graphs for pesticides in Example 1 and Comparative Examples 2-3 of the present invention. Figure 3 The diagram shows the control effect of pesticides on aphids on Chinese cabbage in Example 1 and Comparative Examples 2-3 of this invention. Figure 4 Here is a SEM image of the nano-pesticide in Example 2 of this invention; Figure 5 Here is a SEM image of the nano-pesticide in Example 3 of this invention; Figure 6 Here is a SEM image of the nano-pesticide in Comparative Example 4 of this invention; Figure 7 Here is a SEM image of the nano-pesticide in Comparative Example 5 of this invention; Figure 8 The images show the XRD patterns of copper silicate before pickling and silicon dioxide template after pickling in Example 1 of this invention. Figure 9 This is Example 1 of the present invention and XRD pattern of the drug components; Figure 10 This is Example 1 of the present invention and the infrared spectrum of the drug components; Figure 11 This is Example 1 of the present invention and the Raman spectrum of the drug components; Figure 12 This illustrates the effect of different imidacloprid-carrier composite ratios on the loading of the nano-pesticide imidacloprid in Example 1 of the present invention. Figure 13 The diagram shows the sustained-release effect of pesticides on imidacloprid in Example 1 and Comparative Example 6 of this invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. 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.

[0022] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0023] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0024] The performance testing method is as follows: Evaluation of pesticide adhesion to leaves and resistance to rain washout: At room temperature, 0.5 mL of pesticide solution (imidacloprid content 0.4 mg / mL) was sprayed onto the leaves of Chinese cabbage at a 30° angle to the horizontal. After the droplets on the leaf surface dried, deionized water (1 mL each time) was sprayed onto the leaf surface twice to simulate rain washout. After air drying, the leaves were immersed in 10 mL of deionized water, shaken on a shaker for two hours, soaked overnight, and then sonicated to fully extract the pesticide components from the leaf surface into the water. Finally, the imidacloprid content in the solution was determined by ultraviolet spectrophotometry.

[0025] UV radiation resistance measurement test: Each group prepared an acetone solution with an imidacloprid concentration of 1 g / L. 40 μL of the solution was spread on a 2 cm × 2 cm glass slide and air-dried. The slide was then irradiated for 8 hours at a height of 20 cm from a UV lamp (UV wavelength 254 nm, 6 W). Afterward, the slide was removed and placed in 20 mL of deionized water and thoroughly sonicated. The imidacloprid concentration in the solution was measured using a UV spectrophotometer. Each experiment was repeated three times, and the average value was taken.

[0026] Experiment on the preventive effect of nano-pesticides on plants: A 10 mg / L aqueous solution of imidacloprid was prepared using either technical grade imidacloprid, commercially available imidacloprid water dispersible granules (70% imidacloprid content), or a pollen-like, rough-surfaced, hollow nano-pesticide. The solutions were sprayed onto infested plants, and the number of aphids on the plants was counted 3 and 7 days after spraying. Each treatment was repeated three times. The aphid control effect was calculated using the following formula:

[0027] Where C a P represents the number of insects in the control area before treatment. a The number of insects in the treated area after treatment.

[0028] The mass fraction of ammonia in the following description is 25-28%.

[0029] Example 1 Pesticide preparation: Synthesis of Pollen-like Rough-surfaced Hollow Silica Template: The synthesis of pollen-like rough-surfaced hollow silica templates consists of two steps: First, solid silica spheres are prepared using the classic Stöber method. Specifically, 24 mL of ammonia water (25-28% by mass) is added to 81 mL of ethanol, and the mixture is magnetically stirred at 700 rpm for 10 minutes. Then, 4.2 mL of tetraethyl orthosilicate (TEOS) is slowly added dropwise, and the reaction continues for 2 hours. After the reaction is complete, the product is centrifuged and washed alternately with deionized water and anhydrous ethanol to remove unreacted substances and byproducts. The resulting product is dried at 60°C to obtain silica solid sphere powder. Subsequently, the target pollen-like hollow structure was synthesized: 0.13 g of the above-mentioned solid silica spheres were weighed and dispersed in 20 mL of deionized water to obtain a silica solution; 0.17 g of copper nitrate trihydrate was dissolved in 30 mL of deionized water, then 5 mL of ammonia was added and mixed with the silica solution. The mixture was transferred to a high-pressure reactor and subjected to a hydrothermal reaction at 140 °C for 24 hours. After the hydrothermal reaction was completed, the product was collected, centrifuged, washed with deionized water and ethanol, and dried at 60 °C. Its XRD pattern is shown below. Figure 8 As shown in Figure a. 1.0 g of the dried product was immersed in hydrochloric acid solution (1 mol / L) and stirred at 50°C for 4 hours to remove the Cu component. The product was then centrifuged again, washed repeatedly with water and ethanol, and dried a second time at 60°C to obtain the target pollen-like, rough-surfaced hollow silica template, as shown in Figure a. Figure 8 As shown in Figure b, the composition of the pollen-like carrier has changed from copper silicate to silicon dioxide (silicon-based template).

[0030] Synthesis of Pollen-like Rough-surface Hollow Nanopesticides: A modified impregnation method was used to synthesize nanopesticide formulations. First, 50 mg of sucrose was dissolved in 0.5 mL of deionized water to form a sucrose aqueous solution. Separately, 60 mg of imidacloprid (IMI) was completely dissolved in 10 mL of acetone. 90 mg of pollen-like rough-surface hollow silica was added to the imidacloprid solution, and the mixture was stirred at room temperature for 1.5 h. Subsequently, the solution was rotary evaporated under reduced pressure, and then the pre-prepared sucrose aqueous solution was added. Rotary evaporation continued until the solvent was completely removed, yielding pollen-like rough-surface hollow nanopesticides, i.e., pollen-like imidacloprid nanopesticides.

[0031] The morphology of pollen-like, rough-surfaced, hollow nanopesticides is as follows: Figure 1 As shown, the pesticide exhibits good monodispersity and has numerous pollen-like spiny structures on its surface. These spiny structures provide the pesticide with more contact sites on the crop leaves, thereby significantly enhancing its interaction with the crop leaves. This allows the pesticide to adhere efficiently to the crop leaves and effectively resist rain washout. Figure 1 (b) shows the TEM image and energy dispersive spectroscopy image of the pesticide, where N, C and Cl are characteristic elements of imidacloprid, indicating that imidacloprid is relatively uniformly dispersed on the entire pollen-like silica-based carrier.

[0032] Comparative Example 1 Pure deionized water was used as a comparison.

[0033] Comparative Example 2 Imidacloprid technical grade (purity ≥97%) was used as a pesticide.

[0034] Comparative Example 3 Commercially available imidacloprid water dispersible agent (containing 70% active ingredient by mass) was used as a pesticide.

[0035] As shown in Table 1, the initial imidacloprid deposition amount of the pollen-like, rough-surfaced, hollow nanoparticle pesticide reached 3.89 μg / cm³. The evaluation of pesticide foliar adhesion and resistance to rain washout was conducted. 2 Even after two simulated rain washes, the residual imidacloprid level remained as high as 2.05 μg / cm³. 2 The initial imidacloprid deposition of the commercially available imidacloprid dispersant (Comparative Example 3) was 1.82 μg / cm³. 2 After two simulated rain washes, the amount of imidacloprid residue on the leaf surface was only 0.43 μg / cm³. 2 Experimental results showed that the initial spray deposition amount and rain erosion resistance of the pollen-like surface rough hollow nano-pesticide were 2.1 times and 4.8 times that of commercially available imidacloprid dispersant, respectively, demonstrating excellent leaf surface adhesion performance.

[0036] Imidacloprid is easily decomposed under ultraviolet radiation, leading to a decrease in its efficacy. Therefore, improving the UV resistance of pesticides is one of the most effective ways to fundamentally reduce pesticide usage. Figure 2 The UV resistance of imidacloprid technical, commercially available imidacloprid water dispersible agent, and pollen-like surface rough hollow nano-pesticide was evaluated after 8 hours. After 8 hours of UV irradiation, the residual rate (active ingredient) of imidacloprid in the novel pollen-like surface rough hollow nano-pesticide was still as high as 76.8%, significantly higher than that of commercially available imidacloprid water dispersible agent (59.2%) and imidacloprid technical (44.9%), demonstrating the excellent UV resistance of the novel pollen-like surface rough hollow nano-pesticide.

[0037] Figure 3 To compare the control efficacy of different treatments against aphids on Chinese cabbage, the novel pollen-like, rough-surfaced, hollow nano-pesticide achieved a 100% control rate within 3 days. Seven days after application, the control rate of imidacloprid technical was 65.2%, compared to 62.1% for commercially available imidacloprid and 92.2% for the pollen-like, rough-surfaced, hollow nano-pesticide. Therefore, the pollen-like, rough-surfaced, hollow nano-pesticide is significantly more effective than commercially available imidacloprid in controlling aphids on Chinese cabbage, increasing the control rate by 30.1%.

[0038] Figure 9 The X-ray diffraction (XRD) pattern of the nanopesticide prepared in Example 1 is shown. In the pattern, the diffraction peaks appearing at 2θ = 19.0°, 23.7°, and 26.2° can be attributed to the characteristic diffraction peaks of sucrose. Meanwhile, the broad diffraction signal distribution between 20° and 30° is highly consistent with the characteristic diffraction peaks of amorphous silica. Notably, the clearly visible diffraction peaks at 2θ = 13.8°, 15.0°, 16.5°, and 18.5° confirm the presence of crystalline imidacloprid. In summary, the XRD analysis results strongly demonstrate the successful construction of a silicon-based nanopesticide co-supported with sucrose and imidacloprid.

[0039] Fourier transform infrared (FT-IR) spectroscopy results (Figure 10) confirmed the chemical composition of the silicon-based nanopesticide in Example 1. In the spectrum, characteristic stretching vibration peaks derived from sucrose are clearly visible, including -OH (3350 cm⁻¹). -1 -CH2- (2980 cm) -1 ) and COC (1100 cm -1 Absorption peaks such as ) were observed. Simultaneously, the characteristic signal of imidacloprid was also revealed, primarily at 1560 cm⁻¹. -1 C=C stretching vibration at 1230 cm -1 C=N stretching vibration at 1290 cm -1The NO absorption band at [location missing]. These FT-IR results further strongly demonstrate the successful synthesis of silicon-based nanopesticides.

[0040] To further confirm the composition of the synthesized silicon-based nanopesticide, we performed Raman spectroscopy analysis (Figure 11), focusing on identifying the characteristic peaks of the imidacloprid molecule. Imidacloprid was found at 986, 1267, 1575, 3047, and 3081 cm⁻¹. -1 The spectrum exhibits typical characteristic absorption peaks, which are also present in the Raman spectra of nanopesticides, confirming the efficient loading of imidacloprid onto the carrier. Furthermore, in the Raman spectrum of Example 1, distinct absorption peaks attributed to sucrose characteristic vibrations (such as 538, 2907, and 2938 cm⁻¹) were also observed. -1 This indicates that sucrose has been successfully bound to the carrier surface. In summary, the Raman and infrared spectral analysis results are highly consistent with the aforementioned characterization analyses, jointly confirming the successful preparation of the composite nanopesticide.

[0041] Following the above-mentioned method for synthesizing pollen-like, surface-rough hollow nanopesticides, the mass of the pollen-like, surface-rough hollow silica carrier added to the imidacloprid solution was varied to obtain different nanopesticides with mass ratios of imidacloprid to carrier of 1:4, 1:3, 1:2, and 1:1.

[0042] Figure 12 To investigate the effect of different imidacloprid-carrier composite ratios on the imidacloprid loading of nano-pesticides in Example 1 of this invention, 20 mg of pesticides synthesized with different composite ratios were placed in 200 ml of deionized water and magnetically stirred for 48 h until the drug components were fully released into the solution. The imidacloprid content in the solution was then measured. As shown in the figure, when the imidacloprid-carrier composite ratio is 2:3, the imidacloprid loading of the nano-pesticide reaches its maximum value. Therefore, 2:3 is the preferred optimal composite ratio of imidacloprid and carrier.

[0043] Example 2 Pesticide Preparation: Following the same preparation method as in Example 1, solid silica sphere templates were obtained. 0.13 g of solid silica spheres were dispersed in 20 mL of deionized water to obtain a silica solution. 0.17 g of copper nitrate trihydrate was dissolved in 30 mL of deionized water, and then 10 mL of ammonia was added and mixed with the silica solution. The resulting mixture was subjected to a hydrothermal reaction at 140°C for 24 hours. The product was then centrifuged, washed with deionized water and ethanol, and dried at 60°C. Subsequently, 1.0 g of the dried product was soaked in hydrochloric acid solution (1 mol / L), stirred at 50°C for 4 hours, centrifuged, washed several times with water and ethanol, and dried again at 60°C to obtain a pollen-like, rough-surfaced hollow silica template. The synthesis method of the pollen-like, rough-surfaced hollow nanopesticide remained unchanged from Example 1.

[0044] The morphology of the synthesized nanopesticide in this embodiment is as follows: Figure 4 As shown, the pollen-like carrier is covered with spiny structures, which can effectively increase the contact area with crop leaves and thus improve the leaf adhesion rate of pesticides. Its initial imidacloprid deposition reached 3.45 μg / cm³. 2 Even after two simulated rain washes, the residual imidacloprid level remained as high as 2.0 μg / cm³. 2 Its leaf surface adhesion is much higher than that of imidacloprid technical and commercially available imidacloprid water dispersible agent.

[0045] Example 3 Pesticide preparation: Following the same preparation method as in Example 1, a solid silica sphere template was obtained. 0.13 g of solid silica spheres were dispersed in 20 mL of deionized water to obtain a silica solution. 0.17 g of copper nitrate trihydrate was dissolved in 30 mL of deionized water, and then 5 mL of ammonia was added and mixed with the silica solution. The resulting mixture was subjected to a hydrothermal reaction at 120°C for 24 hours. The product was then centrifuged, washed with deionized water and ethanol, and dried at 60°C. Subsequently, 1.0 g of the dried product was soaked in hydrochloric acid solution (1 mol / L), stirred at 50°C for 4 hours, centrifuged, washed several times with water and ethanol, and dried again at 60°C to obtain a pollen-like, rough-surfaced, hollow silica template.

[0046] The method for further synthesis of pollen-like, rough-surfaced, hollow nanopesticides remains unchanged from that in Example 1.

[0047] The morphology of the synthesized nanopesticide in this embodiment is as follows: Figure 5 As shown, the pollen-like carrier is covered with spiny structures, which can effectively increase the contact area with crop leaves and thus improve the leaf adhesion rate of pesticides. Its initial imidacloprid deposition reached 3.27 μg / cm³. 2 Even after two simulated rain washes, the residual imidacloprid level remained as high as 1.71 μg / cm³. 2 Its leaf surface adhesion is much higher than that of imidacloprid technical and commercially available imidacloprid water dispersible agent.

[0048] Comparative Example 4 Pesticide preparation: Following the preparation method of Example 1, a silica solid sphere template was obtained. 0.13 g of silica solid spheres were dispersed in 20 mL of deionized water to obtain a silica solution. 0.17 g of copper nitrate trihydrate was dissolved in 30 mL of deionized water, and then 1 mL of ammonia was added and mixed with the silica solution. The resulting mixture was subjected to a hydrothermal reaction at 120°C for 24 hours. The product was then centrifuged, washed with deionized water and ethanol, and dried at 60°C. Subsequently, 1.0 g of the dried product was soaked in hydrochloric acid solution (1 mol / L), stirred at 50°C for 4 hours, centrifuged, washed several times with water and ethanol, and dried again at 60°C. The further synthesis method of the nano-pesticide remained unchanged from Example 1.

[0049] The morphology of the nanopesticide synthesized in this comparative example is as follows: Figure 6 As shown, although the carrier exhibits good dispersibility, no spiky structures develop on its surface, thus failing to effectively increase the contact area with crop leaves and consequently providing almost no improvement in pesticide adhesion to leaves. The initial imidacloprid deposition rate was 2.42 μg / cm³. 2 After two simulated rain washes, the residual imidacloprid was only 0.53 μg / cm³. 2 Its leaf surface adhesion amount is only slightly higher than that of imidacloprid technical and commercially available imidacloprid water dispersible agent.

[0050] Comparative Example 5 Pesticide preparation: Following the same preparation method as in Example 1, solid silica sphere templates were obtained. 0.13 g of solid silica spheres were dispersed in 20 mL of deionized water to obtain a silica solution. 0.17 g of copper nitrate trihydrate was dissolved in 30 mL of deionized water, and then 5 mL of ammonia was added and mixed with the silica solution. The resulting mixture was subjected to a hydrothermal reaction at 80°C for 24 hours. The product was then centrifuged, washed with deionized water and ethanol, and dried at 60°C. Subsequently, 1.0 g of the dried product was soaked in hydrochloric acid solution (1 mol / L), stirred at 50°C for 4 hours, centrifuged, washed several times with water and ethanol, and dried again at 60°C. The further synthesis method of the nano-pesticide remained unchanged from Example 1.

[0051] The morphology of the nanopesticide synthesized in this comparative example is as follows: Figure 7 As shown, although the carriers exhibited good dispersibility, their inconsistent sizes and lack of any spiny structures on their surface prevented them from effectively increasing the contact area with crop leaves, thus barely improving the pesticide's leaf adhesion rate. The initial imidacloprid deposition rate was 2.66 μg / cm³. 2 After two simulated rain washes, the residual imidacloprid was only 0.60 μg / cm³. 2 Its leaf surface adhesion amount is almost equivalent to that of imidacloprid technical and commercially available imidacloprid water dispersible agent. It failed to achieve the expected effect of high adhesion from the carrier.

[0052] Comparative Example 6 The only difference from Example 1 is that sucrose was not used in the synthesis of the pollen-like surface-roughened hollow nanopesticide. Specifically, 60 mg of imidacloprid (IMI) was completely dissolved in 10 mL of acetone. 90 mg of pollen-like surface-roughened hollow silica was added to the imidacloprid solution, and the mixture was stirred at room temperature for 1.5 h. Subsequently, the solution was rotary evaporated under reduced pressure to obtain the pollen-like surface-roughened hollow nanopesticide.

[0053] The results showed that in Comparative Example 6, which did not contain added sucrose, the initial imidacloprid deposition amount was 2.82 μg / cm³. 2 After two simulated rain washes, the residual imidacloprid was 1.12 μg / cm³. 2 The amount of imidacloprid adhering to the leaf surface was significantly lower than in Example 1, indicating that the introduction of sucrose is beneficial to improving the leaf surface adhesion performance of nano-pesticides. This is because sucrose molecules are rich in -OH (3350 cm⁻¹) -1 -CH2- (2980 cm) -1 ) and COC (1100 cm -1 Functional groups ( ) Figure 10 It can form hydrogen bonds or intermolecular forces with the waxy layer and other polar groups on the surface of plant leaves, thereby enhancing the adhesion of nano-pesticides to the leaf surface and their resistance to rain erosion.

[0054] Furthermore, the addition of sucrose significantly improved the sustained-release performance of the nano-pesticide. Specifically, 20 mg of the pesticide prepared in Example 1 (imidacloprid to carrier mass ratio of 2:3) was dissolved in 5 mL of deionized water. The resulting solution was poured into a dialysis bag, which was then placed in 195 mL of deionized water. At regular intervals, 5 mL of solution was removed, and another 5 mL of deionized water was added. The absorbance was measured using a UV spectrophotometer, and the content of the sustained-release imidacloprid was calculated. The test method for Comparative Example 6 was the same as that for Example 1; Figure 13 As shown, Example 1 with added sucrose gradually released imidacloprid over 72 hours, while Comparative Example 6 without added sucrose released almost all of the imidacloprid within 2 hours. This is because, during the material formation process, sucrose acts as an auxiliary structure and encapsulating component, which can encapsulate imidacloprid molecules in the cavities and mesoporous structures of the nanomaterial. After application, sucrose gradually dissolves and diffuses in the aqueous environment, allowing the drug molecules to be released continuously in a controlled manner, thereby prolonging the duration of efficacy, reducing the instantaneous loss of active ingredients, and endowing this type of pollen-like rough hollow nanopesticide with excellent sustained-release characteristics and application stability.

[0055] Table 1. Pesticide leaf adhesion performance of each group

[0056] This invention aims to provide a method for preparing a pollen-like, rough-surfaced, hollow nanopesticide and its product. This nanopesticide, mimicking the adhesion mechanism of pollen, significantly enhances its adhesion to crop leaves and its resistance to rain washout through its unique pollen-like rough surface structure. It also possesses excellent resistance to UV degradation, thus achieving superior insecticidal effects at lower application concentrations.

[0057] The above 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 with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a pollen-like imidacloprid nanopesticide, characterized in that: Includes the following steps: S1. A hydrothermal reaction is carried out after mixing solid silica spheres, water, copper nitrate, and ammonia. The mass ratio of solid silica spheres to ammonia in the ammonia solution is 1:8 - 1:

20. The hydrothermal reaction temperature is 120-140℃. S2. The product after the hydrothermal reaction of S1 is immersed in hydrochloric acid and acid washed to obtain pollen-like rough hollow silica. S3. Dissolve sucrose in water to form a sucrose aqueous solution; dissolve imidacloprid in acetone, add pollen-like rough-surfaced hollow silica, stir and then rotary evaporate, then add the sucrose aqueous solution, and rotary evaporate to obtain the pollen-like imidacloprid nanopesticide.

2. The method for preparing the pollen-like imidacloprid nanopesticide according to claim 1, characterized in that: In S1, solid silica spheres were prepared using the classic Stöber method.

3. The method for preparing the pollen-like imidacloprid nanopesticide according to claim 1, characterized in that: In S1, the mass ratio of solid silica spheres to copper nitrate is 13:17; the volume ratio of solid silica spheres to water is 0.13 g: 20-50 mL; and the volume ratio of solid silica spheres to ammonia is 0.13 g: 5-10 mL.

4. The method for preparing the pollen-like imidacloprid nanopesticide according to claim 1, characterized in that: In S1, the hydrothermal reaction takes 10-36 h.

5. The method for preparing the pollen-like imidacloprid nanopesticide according to claim 1, characterized in that: In S2, the concentration of hydrochloric acid is 1 mol / L, the pickling temperature is 50℃, and the time is 4 h.

6. The method for preparing the pollen-like imidacloprid nanopesticide according to claim 1, characterized in that: In S3, the mass ratio of sucrose to imidacloprid is 5:

6.

7. The method for preparing the pollen-like imidacloprid nanopesticide according to claim 1, characterized in that: In S3, the mass ratio of imidacloprid to pollen-like rough-surfaced hollow silica is 1-2:1-4.

8. A method for preparing the pollen-like imidacloprid nanopesticide according to any one of claims 1-7, characterized in that: In S3, the ratio of sucrose to water is 50 mg: 0.5 mL; the ratio of imidacloprid to acetone is 60 mg: 10 mL.

9. A pollen-like imidacloprid nanopesticide, characterized in that: It is prepared using the method for preparing pollen-like imidacloprid nanopesticides as described in any one of claims 1-8.

10. The application of the pollen-like imidacloprid nanopesticide as described in claim 9 in the control of aphids on Chinese cabbage.

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