A nanocarrier and its preparation method and application

Abstract

The present invention discloses a nanocarrier, its preparation method, and application. The structural formula of the nanocarrier is one of the following structures: #imgabs0#, wherein n1=20 and n2=10. The present invention utilizes polymerization-induced self-assembly combined with RAFT polymerization to prepare nanoassemblies with varying surface charges. This polymer is amphiphilic and biocompatible. The addition of nano-adjuvants DMA, TOG, and MAA with varying charges enhances the penetration of the agent within pine wood, effectively resolving the drawbacks of traditional punch-hole injection of emamectin benzoate, which suffers from poor fluidity and penetration within pine wood.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of pesticide nanocarriers, and in particular to a nanocarrier, a preparation method thereof, and an application thereof. Background Art

[0002] Pine wilt disease, also known as pine wilt, is a disease caused by the parasitoid pine nematode parasitizing and feeding on susceptible pine trees, leading to their death. Due to its rapid onset and high mortality rate, it is known as the "cancer" of pine trees, causing large tracts of pine forest dieback and causing enormous losses to my country's pine forest resources. Furthermore, as the pine nematode's adaptability increases, pine wilt disease is gradually spreading to pine forests at high altitudes or in low-temperature areas, posing a serious threat to my country's ecological security. Emamectin benzoate is a widely used agent for the prevention and control of pine wilt disease. Abamectin is a 16-membered macrolide compound produced by fermentation of soil-derived Streptomyces avermitilis. It has high efficacy, low toxicity, and a broad spectrum of biological activity against insects, mites, and nematodes. It has multiple homologues, of which avermectin B1a has the advantages of high activity and low toxicity, making it the primary target for industrialization. Emamectin benzoate is a derivative derived from avermectin B1a and B1b homologues by Merck, USA. Its insecticidal activity in the laboratory is several times greater than that of natural avermectin and has lower toxicity to mammals. Research has shown that avermectin and emamectin benzoate are highly effective, long-lasting, and environmentally friendly pesticides. However, when traditional chemical pesticides are applied to leaves, emamectin benzoate is lost and degraded due to external factors such as rain, UV radiation, and temperature, resulting in low utilization, poor efficacy, and inefficiency. Therefore, it is crucial to develop nano-delivery systems that can enhance the insecticidal efficacy of pesticides while also improving their resistance to adverse weather conditions and reducing environmental risks. Nanomaterials, due to their unique structure, size, and physicochemical properties, have attracted widespread attention in the fields of gene and drug delivery and targeted release. Summary of the Invention

[0003] The technical problem to be solved by the present invention is how to improve the anti-scouring and anti-ultraviolet capabilities of pesticides.

[0004] The present invention solves the above technical problems through the following technical means:

[0005] A nanocarrier having a structural formula of one of the following structures:

[0006]

[0007] Among them, n1=20, n2=10.

[0008] Preferably, the nanocarrier is methacrylic acid MAA or dimethylaminoethyl methacrylate DMA or TOG One of the monomers is used as a monomer, which undergoes a reversible addition-fragmentation-transfer polymerization reaction with a chain transfer agent, 4-cyano-4-(thiobenzoyl)valeric acid, to obtain a hydrophilic macromolecular chain transfer agent; and then the obtained hydrophilic macromolecular chain transfer agent is reacted with benzyl methacrylate BMA to obtain the nanocarrier.

[0009] Preferably, in the process of preparing the hydrophilic macromolecular chain transfer agent, AIBN is used as an initiator and THF is used as a solvent; in the process of reacting with BMA, AIBN is used as an initiator and methanol is used as a solvent.

[0010] The present invention also provides a method for preparing the nanocarrier, comprising the following steps:

[0011] S1, methacrylic acid MAA or dimethylaminoethyl methacrylate DMA or One of TOG, a chain transfer agent 4-cyano-4-(thiobenzoyl)valeric acid, an initiator and a solvent are mixed, and after freeze-thaw cycles under an inert gas atmosphere, a hydrophilic macromolecular chain transfer agent is obtained by heating the mixture.

[0012] S2. Mixing a hydrophilic macromolecular chain transfer agent, benzyl methacrylate (BMA), an initiator, and a solvent, performing a freeze-thaw cycle under an inert gas atmosphere, and then heating the mixture for reaction to obtain the nanocarrier.

[0013] Preferably, in S1 and S2, the inert gas atmosphere is a nitrogen atmosphere; the heating reaction temperature is 70° C., and the time is 24 h.

[0014] Preferably, in S1, the mass of the chain transfer agent 4-cyano-4-(thiobenzoyl)valeric acid is methacrylic acid MAA or dimethylaminoethyl methacrylate DMA or The mass of the initiator is 3.5-11% of one of the mass of the chain transfer agent 4-cyano-4-(thiobenzoyl) valeric acid; the amount ratio of the chain transfer agent 4-cyano-4-(thiobenzoyl) valeric acid to the solvent is 35-112 mg: 5 mL.

[0015] Preferably, in S2, the mass ratio of the hydrophilic macromolecular chain transfer agent to benzyl methacrylate (BMA) is 1:1-6; the weight of the initiator is 0.2-0.55% of the mass of the hydrophilic macromolecular chain transfer agent; and the amount ratio of benzyl methacrylate (BMA) to the solvent is 0.1-1.1 g:0.6-2 ml.

[0016] The present invention also proposes an application of the nanocarrier in pesticide production.

[0017] Preferably, the pesticide is emamectin benzoate.

[0018] The present invention also provides an emamectin benzoate preparation containing the nanocarrier.

[0019] Preferably, the emamectin benzoate preparation is prepared from nanocarriers, water and emamectin benzoate.

[0020] Preferably, the usage ratio of the nanocarrier to emamectin benzoate is 40 ml:30 mg.

[0021] The invention also provides an application of the emamectin benzoate preparation on pine trees.

[0022] The advantages of the present invention are:

[0023] (1) Nanoassemblies with different surface charges were prepared by combining polymerization-induced self-assembly with RAFT polymerization. These polymers are amphiphilic and biocompatible.

[0024] (2) Compared with traditional nanocarriers, the present invention adopts the addition of nano-additives with hydrophilic groups and different charges to improve the adhesion and UV resistance of the formula to the pine needle surface, thereby achieving high adhesion and high retention rate of nanomaterials on the pine needle surface.

[0025] (3) The present invention adds nano-additives DMA, TOG and MAA with different charges to improve the penetration of the agent into the pine wood. This effectively solves the problem of poor fluidity and poor penetration of emamectin benzoate in the pine wood during traditional punch injection. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 : is the H NMR spectrum of the PAA monomer prepared in Example 1 of the present invention;

[0027] Figure 2 1H NMR spectrum of PAA-PBMA (PABs) prepared in Example 1 of the present invention;

[0028] Figure 3 1H NMR spectrum of PTOG-PBMA (POBs) prepared in Example 1 of the present invention;

[0029] Figure 4 This is the H-NMR spectrum of PDMA-PBMA (PCBs) prepared in Example 1 of the present invention;

[0030] Figure 5 Gel permeation chromatography of PTOG (OH), PAA (Anion), PDMA (Cation), POBs (no charge carrier), PABs (negatively charged carrier), and PCBs (positively charged carrier) prepared in Example 1 of the present invention;

[0031] Figure 6The Fourier transform spectra of PTOG (OH), PAA (Anion), and PDMA (Cation) prepared in Example 1 of the present invention are shown in FIG.

[0032] Figure 7 Fourier transform spectra of AVM (free emamectin benzoate), POBs, PABs, and PCBs prepared in Example 1, and AVM@POBs (uncharged carrier loaded with emamectin benzoate), AVM@PABs (negatively charged carrier loaded with emamectin benzoate), and AVM@PCBs (positively charged carrier loaded with emamectin benzoate) prepared in Example 2;

[0033] Figure 8 Dynamic light scattering curves of POBs, PABs, PCBs prepared in Example 1 and AVM@POBs, AVM@PABs, AVM@PCBs prepared in Example 2 of the present invention;

[0034] Figure 9 TGA thermograms (upper figure) and DTG thermograms (lower figure) of POBs, PABs, and PCBs prepared in Example 1 of the present invention and AVM@POBs, AVM@PABs, and AVM@PCBs prepared in Example 2;

[0035] Figure 10 Zeta potential changes of AVM and POBs, PABs, PCBs prepared in Example 1, and AVM@POBs, AVM@PABs, AVM@PCBs prepared in Example 2;

[0036] Figure 11 The encapsulation efficiency of the uncharged carrier, negatively charged carrier, and positively charged carrier for AVM prepared in Example 1 of the present invention;

[0037] Figure 12 Transmission electron microscopy and atomic force microscopy images of POBs, PABs, and PCBs prepared in Example 1 of the present invention, and AVM@POBs, AVM@PABs, and AVM@PCBs prepared in Example 2;

[0038] Figure 13 Contact angle bar graphs of AVM and AVM@POBs, AVM@PABs, and AVM@PCBs prepared in Example 2;

[0039] Figure 14 Contact angle images of AVM and AVM@POBs, AVM@PABs, and AVM@PCBs prepared in Example 2;

[0040] Figure 15 Retention rates of a series of fluorescence images of AVM and AVM@POBs, AVM@PABs, and AVM@PCBs prepared in Example 2;

[0041] Figure 16 Fluorescence micrographs of the nanocarriers POBs, PABs, and PCBs prepared in Example 1 of the present invention after being stained with the fluorescent dye FITC and then subjected to 10 ml and 20 ml of simulated rainwater;

[0042] Figure 17 The AVM concentration was detected by HPLC before and after simulated rainwater flushing of pine needles sprayed with AVM and AVM@POBs, AVM@PABs, and AVM@PCBs prepared in Example 2;

[0043] Figure 18 The AVM residues after UV irradiation of pine needles sprayed with AVM and AVM@POBs, AVM@PABs, and AVM@PCBs prepared in Example 2 for 0.5 h, 1 h, 1.5 h, 2 h, 3 h, and 5 h;

[0044] Figure 19 The AVM residues within 5 days of pine needles sprayed with AVM and AVM@POBs, AVM@PABs, and AVM@PCBs prepared in Example 2 for field experiments;

[0045] Figure 20 This is the NMR spectrum of TOG prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in 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 part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0047] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0048] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the field or according to the product instructions.

[0049] Example 1

[0050] A method for preparing a nanocarrier comprises preparing PTOG using TOG and CTA, preparing PAA using MAA and CTA, and preparing PDMA using DMA and CTA through reversible addition-fragmentation transfer polymerization. The three polymers are then reacted with BMA to generate an uncharged carrier PTOG-PBMA, a negatively charged carrier PAA-PBMA, and a positively charged carrier PDMA-PBMA. The technical route is as follows:

[0051]

[0052] (1) Preparation of amphiphilic block polymer PTOG-PBMA (POBs) (without charge carrier)

[0053] Step 1: Dissolve tetraethylene glycol (5g, 4.44mL) and triethylamine (2.61g, 3.59mL) in 30mL of dichloromethane and pass nitrogen for about 10 minutes to obtain a mixed solution; dilute methacryloyl chloride (2.69g, 2.49mL) with 20mL of dichloromethane and add it dropwise to the above mixed solution using a dropping funnel. React at room temperature for 18h, and then purify by silica gel column chromatography to obtain pure product TOG. The reaction of methacryloyl chloride with tetraethylene glycol produces TOG with a double bond at one end. The synthesized product is characterized by nuclear magnetic hydrogen spectrum (1H-NMR). The results are as follows Figure 20 shown.

[0054] Step 2: Chain transfer agent 4-cyano-4-(thiobenzoyl)valeric acid (CTA) (35 mg), TOG (1 g), and initiator AIBN (5.2 mg) were dissolved in 5 mL of THF, added to an ampoule, and freeze-thawed three times under a nitrogen atmosphere. The reaction was carried out in an oil bath at 70°C for 24 h to obtain a hydrophilic macromolecular chain transfer agent PTOG.

[0055] Step 3: PTOG (60 mg), BMA (100 mg), and AIBN (0.24 mg) were dissolved in 666 μL methanol, freeze-thawed three times in a nitrogen atmosphere, and reacted in an oil bath at 70°C for 24 h to obtain the amphiphilic block polymer PTOG-PBMA (POBs).

[0056] (2) Preparation of PAA-PBMA (PABs) (negatively charged carriers)

[0057] Step 1: Chain transfer agent 4-cyano-4-(thiobenzoyl)valeric acid (CTA) (56 mg), MAA (0.518 g), and initiator AIBN (8.21 mg) were dissolved in 5 mL THF, added to an ampoule, and freeze-thawed three times under a nitrogen atmosphere. The reaction was carried out in an oil bath at 70°C for 24 h to obtain a hydrophilic macromolecular chain transfer agent PAA. Its H NMR spectrum is shown in FIG. Figure 1 As shown;

[0058] Step 2: PAA (1 g), BMA (1.09 g, 1.05 ml), and AIBN (5.1 mg) were dissolved in 1970 μL methanol, and freeze-thawed for three times in a nitrogen atmosphere. The mixture was reacted in an oil bath at 70°C for 24 h to obtain an amphiphilic block polymer PAA-PBMA (PABs). The H NMR spectrum is shown in FIG. Figure 2 As shown;

[0059] (3) Synthesis of PDMA-PBMA (PCBs) (positively charged carriers)

[0060] Step 1: Chain transfer agent 4-cyano-4-(thiobenzoyl)valeric acid (CTA) (111.6 mg), DMA (1.616 ml), initiator AIBN (16.44 mg) were dissolved in 5 mL THF, added to an ampoule, and freeze-thawed three times under nitrogen atmosphere, and reacted in an oil bath at 70 ° C for 24 h to obtain a hydrophilic macromolecular chain transfer agent PDMA. Its H NMR spectrum is as follows: Figure 3 As shown;

[0061] Step 2: PDMA (1 g), BMA (1.09 g, 1.05 ml), and AIBN (2.7 mg) were dissolved in 891 μL of methanol, and the mixture was freeze-thawed three times in a nitrogen atmosphere. The mixture was reacted in an oil bath at 70°C for 24 h to obtain an amphiphilic block polymer PDMA-PBMA (PCBs). The H NMR spectrum of the obtained product was as follows: Figure 4 As shown;

[0062] (4) Characterization of PTOG-PBMA, PAA-PBMA, and PDMA-PBMA

[0063] Using CTA as a chain transfer agent, benzyl methacrylate (BMA), a positively charged monomer dimethylaminoethyl methacrylate (DMA), a negatively charged monomer methacrylic acid (MAA) and TOG as monomers, RAFT polymerization was carried out to obtain PTOG-PBMA (POBs), PAA-PBMA (PABs) and PDMA-PBMA (PCBs) polymerization products. The molecular structure and dispersibility were characterized by nuclear magnetic resonance (1H-NMR), Fourier transform infrared spectroscopy (FT-IR) and gel permeation chromatography (GPC).

[0064] By comparing the characteristic peaks in the NMR spectra, we can see Figure 2 exist Figure 1 BMA was added on the basis of Figure 4 exist Figure 3 BMA was added on this basis, which is consistent with the technical route of the synthesis of negatively charged and positively charged carriers.

[0065] Figure 5This is the gel permeation chromatography of PTOG (OH), PAA (Anion), PDMA (Cation) and POBs (no charged carrier), PABs (negatively charged carrier), and PCBs (positively charged carrier) prepared in Example 1 of the present invention; by observing the peak retention times of POBs, PABs, and PCBs and the peak retention times of OH, Anion, and Cation through the chromatography, it can be seen that POBs, PABs, and PCBs contain OH, Anion, and Cation, respectively.

[0066] Example 2

[0067] A method for preparing emamectin benzoate nanoassemblies comprises the following steps: taking 40 ml of each of the target products PTOG-PBMA, PAA-PBMA, and PDMA-PBMA obtained in Example 1, adding 30 mg of emamectin benzoate, and dropwise adding 400 ml of water with stirring to encapsulate the emamectin benzoate within the nanocarrier to obtain a nanoassembly (AVM@POBs, AVM@PABs, AVM@PCBs) solution; and characterizing the morphology and size of the nanoassemblies using transmission electron microscopy (TEM) and atomic force microscopy (AFM). Characterization methods such as thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FT-IR), and zeta potential confirm that the emamectin benzoate is successfully encapsulated within the nanoassemblies.

[0068] The obtained nanoassembly solution was collected by centrifugation, and the upper liquid was characterized by HPLC to characterize the concentration of emamectin benzoate in the solution and determine the entrapment rate of emamectin benzoate in the nanoassembly. The results are as follows: Figure 11 The solution of the lower nanoassembly is freeze-dried and collected to obtain emamectin benzoate nanoassembly.

[0069] Performance Testing

[0070] The obtained emamectin benzoate nanoassembly was added with water and stirred evenly to obtain a 10% by mass content of the nanoassembly aqueous solution, and then the fluorescent dye fluorescein isothiocyanate was added and stirred to encapsulate the fluorescent dye fluorescein isothiocyanate (FITC) to obtain a FITC-loaded nanoassembly solution. 1 ml was taken and sprayed on the surface of 2g of Pinus massoniana leaves. After being washed by simulated rainwater with precipitation of 10mm, 24mm, and 36mm, the fluorescence retention rate was detected to evaluate the rainwater resistance of the nanoassembly. The results are shown in FIG. Figure 15 shown.

[0071] The nanocarriers prepared in Example 1 were encapsulated with the fluorescent dye fluorescein isothiocyanate (FITC) to obtain FITC-loaded nanoassemblies. The FITC-loaded nanoassemblies were prepared according to the following steps: 1 ml of the obtained emamectin benzoate nanoassemblies were dispersed in 20 ml of water, and then 0.2 mg of FITC was added to the suspension and stirred at 500 rpm for 24 h to obtain fluorescent nanoassemblies, i.e., FITC-loaded nanoassemblies (FITC@POBs, FITC@PABs, FITC@PCBs). At the same time, 0.2 mg of FITC was added to 20 ml of organic phase methanol to prepare a FITC solution. 1 ml of the FITC-loaded nanoassembly and FITC solution were respectively sprayed on 2 g of Pinus massoniana leaves. After being uniformly washed with 10 ml and 20 ml of water using a spray bottle, the fluorescence intensity of nanocarriers with different morphologies before and after rainwater washing was compared by fluorescence microscopy. The adhesion of different nanocarriers to the pine needle surface was further analyzed. The results are shown in FIG. Figure 16 As shown;

[0072] Prepare 20 mg / ml methanol solutions of the positively charged cationic nanopesticide carrier, negatively charged anionic nanopesticide carrier, and uncharged nanopesticide carrier prepared in Example 1, take 1 ml of each and put it into a test tube, then take 1 ml of methanol as the ck group, add 40 mg of emamectin benzoate to each, vortex for 1 minute to completely load the emamectin benzoate, and place them on a stirrer with pure water droplets to dilute the emamectin benzoate concentration to 20 mg / l.

[0073] Take 10ml of the diluted suspension and spray it evenly on 2g of fresh Pinus massoniana needles, marking them as cationic group, anionic group, uncharged group and ck group. After one day of absorption, take half of the samples, simulate rainwater erosion, freeze-dry and extract the liquid phase, and compare the concentration of emamectin benzoate with that of the other half of the samples that have not been washed by rainwater. Figure 17 As shown;

[0074] To study the photostability of nanopesticide carriers, emamectin benzoate solutions loaded with cations, anions, and uncharged carriers, as well as free emamectin benzoate solutions (i.e., the aforementioned solutions diluted to a concentration of 20 mg / l) were sprayed onto fresh pine needles. After the liquid on the surface of the pine needles dried, they were placed in a dark cabinet equipped with a UV lamp at a distance of 100 nm from the light source (Emax = 254 nm, 16.4 W / m 2 After irradiation for 0.5, 1, 1.5, 2, 3, and 5 hours, 2 g of pine needle samples were freeze-dried and ground, extracted with 10 ml of methanol, and the residual emamectin benzoate concentration was measured by liquid chromatography. The results are shown in the figure. Figure 18 As shown;

[0075] A group of wild Pinus massoniana trees were selected in the wild. The emamectin benzoate solution loaded with cations, anions, and charge carriers, as well as the free emamectin benzoate solution (i.e., the solution diluted to a concentration of 20 mg / l) were sprayed on the Pinus massoniana group. Each experiment was repeated five times. On the first, third, and fifth days, 2 grams of pine needles and pine branches were freeze-dried, ground into powder, and extracted with 10 ml of methanol. The emamectin benzoate content (mg / L) in the trees was determined by high-performance liquid chromatography after the first, third, and fifth days. The test results are shown in the table. Figure 19 .

[0076] Figure 7 Fourier transform spectra of AVM (free emamectin benzoate) and POBs, PABs, PCBs, AVM@POBs (no-charge carrier loaded with emamectin benzoate), AVM@PABs (negative-charge carrier loaded with emamectin benzoate), and AVM@PCBs (positive-charge carrier loaded with emamectin benzoate); Figure 7 、 Figure 6 Comparison revealed that the characteristic peaks of the AVM@POBs, AVM@PABs, and AVM@PCBs nanoformulations encompassed those of AVM and POBs, PABs, and PCBs, respectively, with no new peaks appearing. This indicates that AVM has been loaded onto POBs, PABs, and PCBs without any changes in their physicochemical properties, and that the AVM@POBs, AVM@PABs, and AVM@PCBs nanoformulations have been successfully fabricated. This result is consistent with POBs, PABs, and PCBs being good nanocarriers.

[0077] Figure 8 Dynamic light scattering curves of POBs, PABs, PCBs prepared in Example 1 and AVM@POBs, AVM@PABs, AVM@PCBs prepared in Example 2; the particle size distributions of POBs, PABs, PCBs, AVM@POBs, AVM@PABs, AVM@PCBs were measured to be 20.65 nm, 16.13 nm, 32.87 nm, 33.38 nm, 17.69 nm, and 41.80 nm, respectively.

[0078] Figure 9 The TGA thermogram (top) and DTG thermogram (bottom) of the polymers show the smallest mass loss when the temperature is increased from 100°C to 500°C for the polymer PABs and the encapsulated AVM@PABs, indicating that the PABs nanoformulation has the best thermal stability.

[0079] Figure 10The zeta potential changes of AVM, POBs, PABs, and PCBs prepared in Example 1, and AVM@POBs, AVM@PABs, and AVM@PCBs prepared in Example 2 are shown in the zeta potential diagram. The stability of the colloidal dispersions of POBs, PABs, PCBs, and AVM@POBs, AVM@PABs, and AVM@PCBs can be observed. PCBs and their encapsulated AVM@PCBs have the lowest absolute potential values, indicating easy coagulation or aggregation and high stability.

[0080] Figure 11 The encapsulation efficiency of the uncharged carrier, negatively charged carrier, and positively charged carrier prepared in Example 1 is shown. The encapsulation efficiency of the uncharged carrier, negatively charged carrier, and positively charged carrier shows that the positively charged carrier has the highest encapsulation efficiency, almost reaching 80%, demonstrating that the positively charged carrier has a stronger pesticide encapsulation ability than the negatively charged carrier and the uncharged carrier.

[0081] Depend on Figure 12 It can be clearly observed that white spots are attached to the surfaces of AVM@POBs, AVM@PABs, and AVM@PCBs prepared in Example 2, indicating that AVM has been successfully loaded onto the surfaces of POBs, PABs, and PCBs prepared in Example 1.

[0082] Figure 13 Contact angle bar graphs of AVM and AVM@POBs, AVM@PABs, and AVM@PCBs prepared in Example 2; Figure 14 Contact angle images of AVM and AVM@POBs, AVM@PABs, and AVM@PCBs prepared in Example 2. Figure 13 、 14 The contact angles of AVM, AVM@POBs, AVM@PABs and AVM@PCBs with the surface of Masson pine needles were measured to be 99.9°, 61.6°, 53.3° and 55.8° respectively. The contact angles of the three nanocarriers are much smaller than that of pure AVM, which can increase the adsorption on the leaf surface and resist rain erosion, verifying the adhesion of the nanomaterials.

[0083] Figure 15 The retention rates of a series of fluorescence images of AVM and AVM@POBs, AVM@PABs, and AVM@PCBs prepared in Example 2; from the perspective of fluorescence retention, AVM@POBs, AVM@PABs, and AVM@PCBs all have higher retention rates than that of pure AVM, among which AVM@PABs has better retention, indicating that the nanocarrier can effectively protect the drug and prevent drug loss.

[0084] Figure 16The nanocarrier prepared in Example 1 was dyed with fluorescent dye FITC and then washed with 10ml and 20ml of simulated rainwater. Figure 16 Fluorescence results show that the positively charged carriers maintain strong fluorescence after rinsing, indicating that the carriers' strong adhesion effectively prevents the pesticide from being washed away by rainwater. The wax layer on the leaf surface is composed of higher fatty acids, alcohols, and aldehydes. Therefore, the positively charged cationic carriers interact with the negatively charged groups on the leaf surface through electrostatic attraction, improving the deposition efficiency of the pesticide on the target.

[0085] Figure 17 HPLC analysis of AVM concentrations in pine needles sprayed with an AVM solution and the AVM@POBs, AVM@PABs, and AVM@PCBs prepared in Example 2 after simulated rainwater rinsing. The black color represents the AVM concentration before rinsing, while the gray color represents the AVM concentration after rinsing. The figure shows that the positively charged cationic carrier sample retained the highest concentration of emamectin benzoate compared to the pre-rinsing level, accounting for approximately 80% of the unrinsed sample. The uncharged carrier sample and the negatively charged anionic carrier sample each retained approximately 45% of the unrinsed level. The emamectin benzoate concentration in the ck group after rinsing remained at 26% of the original concentration.

[0086] Figure 18 The AVM residue (unit: mg / L) of pine needles sprayed with an AVM solution and AVM@POBs, AVM@PABs, and AVM@PCBs prepared in Example 2 after UV irradiation for 0.5 h, 1 h, 1.5 h, 2 h, 3 h, and 5 h. It can be seen that exposing free emamectin benzoate to UV light shortens the half-life and reduces the insecticidal effect. The photostability of nanopesticides was studied by UV protection of photosensitivity. It was demonstrated that encapsulated nanopesticides have improved photostability compared to free emamectin benzoate. Since microcapsules reduce the possibility of direct contact between pesticides and incident light, photostability can be improved through certain encapsulation methods.

[0087] Figure 19 Figure 5 shows the AVM residue in pine needles sprayed with AVM and the AVM@POBs, AVM@PABs, and AVM@PCBs prepared in Example 2 over a five-day period in a field experiment. The figure shows that positively charged cationic carriers can also improve pesticide retention in the field, effectively controlling pine wood nematodes. This suggests that the strong adhesion of positively charged cationic nanocarriers can effectively prevent pesticides from being washed away by rainwater.

[0088] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An emamectin benzoate preparation, characterized in that: It includes a nanocarrier, and the nanocarrier structural formula is the following structure: ; Among them, n1=20, n2=10.

2. Emamectin benzoate preparation according to claim 1, is characterized in that: The nanocarrier is The monomer undergoes a reversible addition-fragmentation-transfer polymerization reaction with a chain transfer agent, 4-cyano-4-(thiobenzoyl)valeric acid, to obtain a hydrophilic macromolecular chain transfer agent; and then the obtained hydrophilic macromolecular chain transfer agent reacts with benzyl methacrylate BMA to obtain the nanocarrier.

3. Emamectin benzoate preparation according to claim 2, is characterized in that: In the process of preparing the hydrophilic macromolecular chain transfer agent, AIBN is used as an initiator and THF is used as a solvent; in the process of reacting with BMA, AIBN is used as an initiator and methanol is used as a solvent.

4. The emamectin benzoate preparation according to any one of claims 1 to 3, wherein: The preparation method of the nanocarrier comprises the following steps: S1. , a chain transfer agent 4-cyano-4-(thiobenzoyl)valeric acid, an initiator and a solvent are mixed, and after freezing and thawing cycles under an inert gas atmosphere, heating reaction is performed to obtain a hydrophilic macromolecular chain transfer agent; S2. Mixing a hydrophilic macromolecular chain transfer agent, benzyl methacrylate (BMA), an initiator, and a solvent, performing a freeze-thaw cycle under an inert gas atmosphere, and then heating the mixture for reaction to obtain the nanocarrier.

5. Emamectin benzoate preparation according to claim 4, is characterized in that: In S1 and S2, the inert gas atmosphere is a nitrogen atmosphere; the heating reaction temperature is 70° C. and the time is 24 h.

6. The emamectin benzoate preparation according to claim 4, wherein: In S1, the mass of the chain transfer agent 4-cyano-4-(thiobenzoyl)valeric acid is The mass of the initiator is 3.5-11% of the mass of the chain transfer agent 4-cyano-4-(thiobenzoyl)valeric acid; the mass ratio of the chain transfer agent 4-cyano-4-(thiobenzoyl)valeric acid to the solvent is 35-112 mg:5 mL.

7. The emamectin benzoate preparation according to claim 4, wherein: In S2, the mass ratio of the hydrophilic macromolecular chain transfer agent to benzyl methacrylate (BMA) is 1:1-6; the weight of the initiator is 0.2-0.55% of the mass of the hydrophilic macromolecular chain transfer agent; and the amount ratio of benzyl methacrylate (BMA) to the solvent is 0.1-1.1 g:0.6-2 ml.

8. Use of the emamectin benzoate preparation according to any one of claims 1 to 7 in preventing and treating pine nematode disease.

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