Imidacloprid nano-pesticide and preparation method thereof

Abstract

This invention discloses an imidacloprid nanopesticide and its preparation method. The preparation method includes: mixing rod-shaped silica, water, copper nitrate, and ammonia water evenly, and then carrying out a hydrothermal reaction at 130-140℃; the mass ratio of rod-shaped silica to ammonia water is 1:8-14; taking the product after the hydrothermal reaction and soaking it in hydrochloric acid solution to obtain a silicon-based template; dissolving imidacloprid in acetone, adding the silicon-based template, stirring, and then rotary evaporating the solution, followed by adding a sucrose aqueous solution and rotary evaporating again to obtain the imidacloprid nanopesticide. The pesticide of this invention has 2.9 times the adhesion to commercially available imidacloprid water-dispersible particles on pakchoi leaves, and its retention rate in simulated rainfall is 5.16 times that of commercially available imidacloprid water-dispersible particles, fully demonstrating its excellent anti-erosion performance. In addition, this nanopesticide has excellent UV resistance and aphid control capabilities.

Description

Technical Field

[0001] This invention relates to the field of nanopesticide technology, specifically to an imidacloprid nanopesticide and its preparation method. Background Technology

[0002] Traditional pesticides face a severe challenge in agricultural production due to their low utilization rate. When pesticide solutions are sprayed onto crop leaves, the hydrophobic nature of most plant leaf surfaces causes pesticide droplets to bounce and roll off, resulting in a low initial deposition rate. Furthermore, sprayed pesticides are easily washed away by rainwater or rapidly decompose under ultraviolet light, leading to significant loss of active ingredients and a short duration of effectiveness. To achieve ideal control effects, it is often necessary to increase the dosage or the number of sprays, which not only increases agricultural costs but also causes serious environmental pollution and ecological risks to soil, water sources, and non-target organisms.

[0003] In recent years, nanotechnology has been applied to pesticide delivery systems, aiming to improve pesticide utilization efficiency by loading pesticide active ingredients onto nanocarriers. Silica nanomaterials have been extensively studied due to their high specific surface area, tunable structure, and good biocompatibility. However, existing silica nanopesticides still have some problems, such as weak physical and chemical interactions with leaf surfaces, resulting in poor adhesion and insufficient resistance to rain washout; at the same time, complex preparation processes and high costs also limit their large-scale application. Therefore, developing a novel nanopesticide delivery system that can mimic the efficient adhesion mechanism of organisms, possesses strong leaf surface adhesion, is resistant to rain washout and UV degradation, and can continuously release active ingredients is of great significance for improving pesticide utilization efficiency, ensuring food security, and promoting sustainable agricultural development. Summary of the Invention The technical problem to be solved by this invention is how to improve the UV resistance, rain washout resistance and slow release performance of imidacloprid pesticides.

[0004] The present invention solves the above-mentioned technical problems through the following technical means: A method for preparing an imidacloprid nanopesticide includes the following steps: S1. A hydrothermal reaction is carried out after uniformly mixing rod-shaped silica, water, copper nitrate, and ammonia. The mass ratio of the rod-shaped silica to ammonia in the ammonia solution is 1:8-14. The temperature of the hydrothermal reaction is 130-140℃. S2. Take the product after the hydrothermal reaction and soak it in hydrochloric acid solution to obtain a silicon-based template; S3. Dissolve imidacloprid in acetone, add a silicon-based template, stir, and then rotary evaporate the solution. Add a sucrose aqueous solution and rotary evaporate to obtain the imidacloprid nanopesticide.

[0005] Preferably, the mass ratio of the rod-shaped silica to the ammonia in the ammonia water is 1:8-14; it can be one of 1:8.75, 1:9, 1:10, 1:11, 1:12, 1:13, or 1:13.57.

[0006] Preferably, in S1, the ratio of the rod-shaped silica to ammonia is 0.13 g: 5-7 mL.

[0007] Preferably, in S1, the method for preparing the rod-shaped silica includes the following steps: dissolving polyvinylpyrrolidone in n-pentanol, sequentially adding ethanol, water, sodium citrate aqueous solution, ammonia and tetraethoxysilane, mixing evenly, and allowing the reaction to stand to obtain the rod-shaped silica.

[0008] Preferably, in S1, the hydrothermal reaction takes 15-30 h.

[0009] Preferably, in S1, the mass ratio of rod-shaped silicon dioxide to copper nitrate is 1:2.

[0010] Preferably, in step S2, the concentration of the hydrochloric acid solution is 0.5-2 mol / L; the soaking temperature is 25-50℃, and the soaking time is 2-6 h.

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

[0012] Preferably, in S3, the ratio of imidacloprid to acetone is 60 mg: 10 mL.

[0013] Preferably, in S3, the mass ratio of imidacloprid to silicon-based template is 1-2:1-4.

[0014] Preferably, in S3, the mass ratio of imidacloprid to silicon-based template is 1-2:1-3.

[0015] Preferably, in S3, the mass ratio of imidacloprid to silicon-based template is 2:3.

[0016] Preferably, in S3, the mass ratio of imidacloprid to sucrose is 6:5.

[0017] Preferably, in S3, the stirring temperature is room temperature and the stirring time is 1.5 h.

[0018] The present invention also proposes an imidacloprid nanopesticide, which is prepared by the aforementioned method for preparing imidacloprid nanopesticides.

[0019] Preferably, the imidacloprid nanopesticide has an imidacloprid loading rate of 19.0-39.3%.

[0020] The present invention also proposes an application of the imidacloprid nanopesticide in the control of aphids on cabbage.

[0021] This invention draws inspiration from the superior adhesion mechanisms of bacteria in the biological world. Pili are essential components of many Gram-negative pathogens, playing a crucial role in promoting bacterial interactions and attachment to host cells, and are vital for bacterial pathogenicity. Bacteria lacking pili are easily expelled through mechanisms such as mucosal cell ciliary movement, intestinal peristalsis, or urinary flushing, resulting in loss of pathogenicity. This efficient bioadhesion mechanism provides inspiration for the design of pesticide carriers. Inspired by the superior adhesion properties of intestinal colonizing bacteria, this invention designs a rod-shaped, rough-surfaced hollow silica nanocarrier, whose pili-like surface structure mimics the adhesion characteristics of intestinal bacteria. By loading imidacloprid and sucrose using a vacuum impregnation method, a bacteria-mimicking, rough-surfaced, hollow rod-shaped nanopesticide was successfully prepared. Experimental results show that the adhesion of the rough-surfaced, hollow rod-shaped nanopesticide on pakchoi leaves is 2.9 times that of commercially available imidacloprid water-dispersible particles, and its retention rate in simulated rainfall is 5.16 times that of commercially available imidacloprid water-dispersible particles, fully demonstrating its excellent anti-erosion performance. Furthermore, this nanopesticide exhibits excellent UV resistance and aphid control capabilities. The development of this rough-surfaced hollow rod-shaped nanopesticide provides a highly efficient and sustainable new strategy for the green control of agricultural pests and diseases, and is expected to significantly reduce pesticide use, lower environmental pollution, and contribute to the sustainable development of agriculture in the future. Attached Figure Description

[0022] Figure 1 (a) SEM image and (b) TEM image and energy dispersive spectroscopy of the novel biomimetic bacterial rod-shaped hollow nanopesticide of the present invention; Figure 2 The graph shows the UV resistance of pesticides in each test group of this invention. Figure 3 The graph shows the control effect of pesticides on aphids on Chinese cabbage in each test group 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 This is the XRD pattern of the silicon-based template composition in Embodiment 1 of the present 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 is an example of the effect of different imidacloprid-carrier composite ratios on the imidacloprid loading in Example 1 of the present invention. Figure 13 The slow-release curves of the 6-nanometer pesticide in Example 1 and the comparative example of the present invention are shown. Detailed Implementation

[0023] 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.

[0024] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0025] 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.

[0026] The ammonia solution mentioned below refers to ammonia solution with a mass fraction of 25%-28%.

[0027] 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, 1 mL of deionized water 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. The imidacloprid content in the solution was determined by ultraviolet spectrophotometry.

[0028] 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.

[0029] Experiment on the preventive effect of nano-pesticides on plants: A 10 mg / L aqueous solution of imidacloprid was prepared using technical grade imidacloprid, commercially available imidacloprid water dispersible granules, and a hollow nano-pesticide with a rough surface resembling bacterial rods. The solutions were sprayed onto infested plants, and the number of aphids on the plants was recorded 3 and 7 days after spraying. Each treatment was repeated 3 times. The aphid control effect was calculated using the following formula:

[0030] Where C a P represents the number of insects in the control area before control measures are implemented. a The number of insects in the treated area after treatment.

[0031] Comparative Example 1 Pure deionized water was used as a comparison.

[0032] Comparative Example 2 Imidacloprid technical grade (purity ≥97%) was used as a comparison.

[0033] Comparative Example 3 Imidacloprid water dispersible agent (containing 70% active ingredient by mass) was used as a comparison.

[0034] Example 1 Preparation of imidacloprid nanopesticides: Synthesis of silicon-based templates: 15 g of polyvinylpyrrolidone (PVP) was completely dissolved in 150 mL of n-pentanol. Then, 15 mL of anhydrous ethanol, 4.2 mL of deionized water, 1.5 mL of 0.18 M sodium citrate aqueous solution, 3.4 mL of ammonia (25%-28% by mass), and 1.5 mL of tetraethoxysilane (TEOS) were added sequentially. After each addition, the mixture was stirred for 3 minutes to ensure thorough mixing. The resulting reaction mixture was allowed to stand for 16 hours and then centrifuged. The resulting precipitate was washed repeatedly with deionized water and ethanol, and dried at 60 °C to obtain rod-shaped silica.

[0035] 0.13 g of the above-mentioned rod-shaped silica was dispersed in 20 mL of deionized water to obtain a silica solution. Simultaneously, 0.26 g of copper nitrate trihydrate was dissolved in 30 mL of deionized water, followed by the addition of 7 mL of ammonia to obtain a copper solution. The silica and copper solutions were mixed thoroughly, and the resulting mixture was subjected to a hydrothermal reaction at 140 °C for 24 hours. After the reaction, the product was centrifuged, washed repeatedly with deionized water and ethanol, and dried at 60 °C. The XRD pattern of the obtained product is shown below. Figure 8 As shown in Figure a, all peaks are clearly attributed to copper silicate (JCPDS 03-0219). Next, 1.0 g of the dried product was placed in hydrochloric acid solution (1 mol / L), soaked and stirred at 50°C for 4 hours to remove the copper component. It was then centrifuged again, washed repeatedly with deionized water and ethanol, and dried at 60°C to obtain a rough-surfaced rod-shaped hollow silica template, i.e., the silicon-based template. The XRD pattern of this silicon-based template is shown in Figure a. Figure 8 As shown in b, the corresponding JCPDS card number is 01-0438, which is... Figure 8 It can be seen that the composition of the rod-shaped support has changed from copper silicate to silicon dioxide (silicon-based template).

[0036] Synthesis of Bacterial Rod-Shaped Hollow Nanopesticides with Rough Surfaces. A modified impregnation method was used to synthesize the nanopesticide formulation. 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 was completely dissolved in 10 mL of acetone. 90 mg of a rough-surfaced hollow silica template 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 the pre-prepared sucrose aqueous solution was added. Rotary evaporation continued until the solvent was completely removed, yielding the final bacterial rod-shaped hollow nanopesticide with rough surface, namely the imidacloprid nanopesticide.

[0037] The morphology of hollow nanopesticides with rough, bacterial rod-like surfaces is as follows: Figure 1 As shown, the pesticide exhibits good monodispersity and its surface has numerous bacterial hair-like structures. These hair-like structures provide the pesticide with more contact sites on the crop leaves, thereby significantly increasing 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 (EDS) image of the pesticide, where N, C, and Cl are characteristic elements of imidacloprid, indicating that imidacloprid is relatively uniformly dispersed throughout the rod-shaped silicon-based carrier. Table 1 shows that the initial imidacloprid deposition amount of the hollow nanopesticide with a rough surface resembling bacterial rods reached 5.32 μg / cm³. 2 Even after two simulated rain washes, the residual imidacloprid level remained as high as 2.22 μg / cm³. 2The residual amount of commercially available imidacloprid dispersant (Comparative Example 3) on the leaf surface after two simulated rain washes was only 0.43 μg / cm³. 2 Therefore, the novel biomimetic bacterial rod-shaped hollow nano-pesticide has 5.16 times the resistance to rain erosion compared to traditional commercially available imidacloprid dispersants, demonstrating its excellent leaf surface adhesion ability.

[0038] 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 the novel biomimetic bacterial rod-shaped hollow nanoparticles with rough surfaces was compared with that of commercially available imidacloprid technical, commercially available imidacloprid water dispersible agent, and biomimetic bacterial rod-shaped hollow nanoparticles within 8 hours. After 8 hours of UV irradiation, the imidacloprid retention rate (active ingredient) of the novel biomimetic bacterial rod-shaped hollow nanoparticles was still as high as 69.9%, 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 biomimetic bacterial rod-shaped hollow nanoparticles.

[0039] Figure 3 To compare the control efficacy of different treatments against aphids on Chinese cabbage, the novel biomimetic bacterial rod-shaped hollow nano-pesticide achieved a 100% control rate within 3 days. Seven days after application, the control rate of imidacloprid technical was 65.2%, commercially available imidacloprid was 62.1%, and the novel biomimetic bacterial rod-shaped hollow nano-pesticide was 93.7%. Therefore, the biomimetic bacterial rod-shaped hollow nano-pesticide is significantly more effective than commercially available imidacloprid in controlling aphids on Chinese cabbage, increasing the control rate by 31.6%.

[0040] 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.

[0041] 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- (2980cm) -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 -1 The NO absorption band at [location missing]. These FT-IR results further strongly demonstrate the successful synthesis of silicon-based nanopesticides.

[0042] 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 attributable 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.

[0043] In the pesticide preparation process, by changing the mass of the added rough-surfaced rod-shaped hollow silica template, the mass ratio of the template to imidacloprid was 1:1, 2:1, 3:1, and 4:1, respectively, resulting in nano-pesticides with different composite ratios.

[0044] Figure 12 To investigate the effect of different imidacloprid-carrier composite ratios on the imidacloprid loading of the nano-pesticide 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 to allow the drug components to be fully released into the solution. The imidacloprid content in the solution was then measured. As shown in the figure, when the carrier:imidacloprid mass ratio was 4:1, 3:1, 2:1, 3:2, and 1:1, the imidacloprid loading was 19.0%, 24.8%, 36.9%, 39.3%, and 36.6%, respectively. When the imidacloprid-carrier composite ratio was 2:3, the imidacloprid loading of the nano-pesticide reached a maximum of 39.3%. Therefore, 2:3 is the preferred optimal composite ratio of imidacloprid and carrier.

[0045] Example 2 Preparation of imidacloprid nanopesticide: Following the preparation method in Example 1, after obtaining a rod-shaped silica template, 0.13 g of the rod-shaped silica template was dispersed in 20 mL of deionized water to obtain a silica solution. 0.26 g of copper nitrate trihydrate was dissolved in 30 mL of deionized water, and then 5 mL of ammonia was added to obtain a copper solution. The silica solution and copper solution were mixed thoroughly, and the resulting mixture was subjected to a hydrothermal reaction at 140 °C for 24 hours. The product was then centrifuged, washed multiple times 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 multiple times with deionized water and ethanol, and dried again at 60 °C to obtain a rough-surfaced rod-shaped hollow silica template. The further synthesis method of the nanopesticide remained unchanged from Example 1.

[0046] The morphology of the synthesized nanopesticide in this embodiment is as follows: Figure 4 As shown, the rod-shaped carrier is covered with spiky 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 4.62 μg / cm³. 2 After two simulated rain washes, the residual imidacloprid level was still as high as 1.92 μg / cm³. 2 Its leaf surface adhesion is much higher than that of imidacloprid technical and commercially available imidacloprid water dispersible agent.

[0047] Example 3 Preparation of imidacloprid nanopesticide: Following the preparation method in Example 1, after obtaining a rod-shaped silica template, 0.13 g of the rod-shaped silica template was dispersed in 20 mL of deionized water to obtain a silica solution. 0.26 g of copper nitrate trihydrate was dissolved in 30 mL of deionized water, and then 7 mL of ammonia was added to obtain a copper solution. The silica solution and copper solution were mixed thoroughly, and the resulting mixture was subjected to a hydrothermal reaction at 130°C for 24 hours. The product was then centrifuged, washed multiple times 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 multiple times with deionized water and ethanol, and dried again at 60°C to obtain a rough-surfaced rod-shaped hollow silica template. The further synthesis method of the nanopesticide remained unchanged from Example 1.

[0048] The morphology of the synthesized nanopesticide in this embodiment is as follows: Figure 5 As shown, the rod-shaped carrier exhibits good dispersibility and is also covered with spiky structures, effectively increasing the contact area with crop leaves and thus improving the leaf adhesion rate of pesticides. Its initial imidacloprid deposition reached 4.81 μg / cm³. 2 After two simulated rain washes, the residual imidacloprid content was still as high as 1.81 μg / cm³. 2Its leaf surface adhesion is much higher than that of imidacloprid technical and commercially available imidacloprid water dispersible agent.

[0049] Comparative Example 4 Pesticide Preparation: Following the same preparation method as in Example 1, after obtaining the rod-shaped silica template, 0.13 g of the rod-shaped silica template was dispersed in 20 mL of deionized water to obtain a silica solution. 0.26 g of copper nitrate trihydrate was dissolved in 30 mL of deionized water, and then 1 mL of ammonia was added to obtain a copper solution. The silica solution and copper solution were mixed thoroughly, and the resulting mixture was subjected to a hydrothermal reaction at 140°C for 24 hours. The product was then centrifuged, washed multiple times 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 multiple times with deionized water and ethanol, and dried again at 60°C. The further preparation method of the nano-pesticide remained unchanged from Example 1.

[0050] The morphology of the nanopesticide synthesized in this comparative example is as follows: Figure 6 As shown, although the rod-shaped carrier exhibits good dispersibility, its surface contains only a few relatively short protrusions, failing to effectively increase the contact area with crop leaves and thus barely improving the pesticide's leaf adhesion rate. Its initial imidacloprid deposition amount was 2.92 μg / cm³. 2 After two simulated rain washes, the residual imidacloprid was only 0.82 μg / cm³. 2 Its leaf surface adhesion amount is only slightly higher than that of imidacloprid technical and commercially available imidacloprid water dispersible agent.

[0051] Comparative Example 5 Pesticide preparation: Following the same preparation method as in Example 1, after obtaining the rod-shaped silica template, 0.13 g of the rod-shaped silica template was dispersed in 20 mL of deionized water to obtain a silica solution. 0.26 g of copper nitrate trihydrate was dissolved in 30 mL of deionized water, and then 7 mL of ammonia was added to obtain a copper solution. The silica solution and copper solution were mixed thoroughly, and the resulting mixture was subjected to a hydrothermal reaction at 90°C for 24 hours. The product was then centrifuged, washed multiple times 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 multiple times with deionized water and ethanol, and dried again at 60°C. The further preparation method of the nano-pesticide remained unchanged from Example 1.

[0052] The morphology of the nanopesticide synthesized in this comparative example is as follows: Figure 7 As shown, although the rod-shaped carrier exhibits good dispersibility, its surface lacks almost no spiky structures, failing to effectively increase the contact area with crop leaves and thus providing virtually no improvement in pesticide adhesion to leaves. Its initial imidacloprid deposition rate was 2.83 μg / cm³.2 After two simulated rain washes, the residual imidacloprid was only 0.78 μg / cm³. 2 Its leaf surface adhesion amount is almost equivalent to that of imidacloprid technical and commercially available imidacloprid water dispersible agent, failing to achieve the expected effect of high adhesion of the carrier.

[0053] Comparative Example 6 The only difference from Example 1 is that sucrose was not used in the synthesis of the nanopesticide. Specifically, the steps included: 60 mg of imidacloprid was completely dissolved in 10 mL of acetone. 90 mg of a rough-surfaced, rod-shaped hollow silica template 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 until the solvent was completely removed, yielding the final biomimetic bacterial rod-shaped, rough-surfaced, hollow nanopesticide.

[0054] Table 1. Pesticide leaf adhesion performance of each group

[0055] The results showed that in Comparative Example 6 without added sucrose, the initial imidacloprid deposition amount was 3.45 μg / cm³. 2 After two simulated rain washes, the residual imidacloprid was 1.21 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.

[0056] Furthermore, the addition of sucrose significantly improved the sustained-release performance of the nano-pesticide. 20 mg of the pesticide obtained in Example 1 (imidacloprid to carrier composite 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 taken out, and then 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 testing method for the pesticide in Comparative Example 6 was the same as that in Example 1. Figure 13As 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 biomimetic bacterial rough-surface hollow nanopesticide with excellent sustained-release properties and application stability.

[0057] This invention provides a method for preparing a rod-shaped hollow nanopesticide with a rough surface that mimics bacterial structure and exhibits excellent leaf adhesion properties. The method first prepares a rod-shaped hollow silica nanocarrier with a rough surface structure similar to bacterial pili through hydrothermal methods and acid etching. Then, using a modified impregnation method, the pesticide active ingredients imidacloprid and sucrose are loaded into the carrier, ultimately yielding a rod-shaped hollow nanopesticide with a rough surface that mimics bacteria. The method precisely controls the morphology of the nanocarrier by adjusting the reactant ratio and conditions, giving it a unique rod-shaped and rough hollow structure. This nanopesticide mimics the adhesion mechanism of bacterial pili, and through its unique rod-shaped rough surface structure, it significantly enhances adhesion to crop leaves and resistance to rain washout, while also possessing excellent resistance to UV degradation, thus achieving better insecticidal effects at lower application concentrations. The adhesion of the rod-shaped hollow nanopesticide with a rough surface that mimics bacteria prepared by this method to pakchoi leaves is 2.9 times that of commercially available imidacloprid water-dispersible particles. Under simulated rainfall conditions, the retention rate of the bacteriophage-like rod-shaped hollow nanopesticide with rough surface is 5.16 times that of commercially available imidacloprid. It also exhibits excellent resistance to UV degradation. The bacteriophage-like rod-shaped hollow nanopesticide shows superior control efficacy against aphids on Chinese cabbage compared to commercially available imidacloprid, with a control rate increase of 31.6%. This invention provides a novel, highly efficient, and sustainable nanopesticide delivery system, which is expected to significantly improve pesticide utilization efficiency, reduce dosage, and decrease environmental pollution.

[0058] 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 an imidacloprid nanopesticide, characterized in that: Includes the following steps: S1. A hydrothermal reaction is carried out after uniformly mixing rod-shaped silica, water, copper nitrate, and ammonia. The mass ratio of the rod-shaped silica to ammonia in the ammonia solution is 1:8-14. The temperature of the hydrothermal reaction is 130-140℃. S2. Take the product after the hydrothermal reaction and soak it in hydrochloric acid solution to obtain a silicon-based template; S3. Dissolve imidacloprid in acetone, add a silicon-based template, stir, and then rotary evaporate the solution. Add a sucrose aqueous solution and rotary evaporate to obtain the imidacloprid nanopesticide.

2. The method for preparing imidacloprid nanopesticide according to claim 1, characterized in that: In S1, the method for preparing the rod-shaped silica includes the following steps: dissolving polyvinylpyrrolidone in n-pentanol, adding ethanol, water, sodium citrate aqueous solution, ammonia and tetraethoxysilane in sequence, mixing evenly, and allowing the reaction to stand to obtain the rod-shaped silica.

3. The method for preparing the imidacloprid nanopesticide according to claim 1, characterized in that: In S1, the hydrothermal reaction takes 15-30 h.

4. The method for preparing imidacloprid nanopesticide according to claim 1, characterized in that: In S1, the mass ratio of rod-shaped silicon dioxide to copper nitrate is 1:

2.

5. The method for preparing the imidacloprid nanopesticide according to claim 1, characterized in that: In S2, the concentration of the hydrochloric acid solution is 0.5-2 mol / L; the soaking temperature is 25-50℃, and the soaking time is 2-6 h.

6. The method for preparing the imidacloprid nanopesticide according to claim 1, characterized in that: In S3, the ratio of imidacloprid to acetone is 60 mg: 10 mL.

7. The method for preparing imidacloprid nanopesticide according to claim 1, characterized in that: In S3, the mass ratio of imidacloprid to silicon-based template is 1-2:1-4.

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

5.

9. An imidacloprid nanopesticide, characterized in that: It is prepared by the method of preparing imidacloprid nanopesticide as described in any one of claims 1-8.

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

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