A pesticide-loaded particle with a spiky morphology, its preparation method and application

Abstract

The present invention discloses a pesticide-loaded particle with a spiky morphology, its preparation method and application, belonging to the technical field of pesticide preparation. The pesticide is loaded into the spiky particles through physical adsorption. The particle size is between 200 and 800 nm, the drug loading amount is between 10% and 20%, and the retention rate on plant leaves is 60% - 80%. The pesticide-loaded particles with a spiky morphology of the present invention have a good leaf adhesion effect, which is very obvious compared with traditional suspending agents and water-dispersible granules. The spiky morphology pesticide-loaded particles of the present invention can improve the stability of pesticides, increase the rain erosion resistance of pesticides, improve the utilization efficiency of pesticides, prolong the pesticide effective period at the same time, reduce the number of pesticide applications, so it can reduce the amount of pesticide used and protect the environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of pesticide preparation, and particularly relates to a pesticide-loaded particle with a spiky morphology, a preparation method thereof, and an application thereof. Background Art

[0002] The hazards caused by traditional pesticides have made the development of safer, more environmentally friendly, and more convenient-to-pack pesticide formulations increasingly important. It can increase the value and attractiveness of pesticide active ingredients, improve the safety of users, reduce the application frequency and total amount of pesticides, thereby reducing their adverse effects on the environment and the pesticide residue rate in agricultural products. Most government regulatory agencies, including the Chinese government, now require the use of cleaner, safer, formulations with minimal environmental impact and that can be used at the lowest dosage rate.

[0003] Traditional pesticide formulations enter the environment through various channels because they cannot effectively adhere to the target leaf surface, resulting in serious environmental problems and posing risks to human health. Only less than 0.1% of the applied pesticides can effectively act on the target organisms. Improving the adhesion of pesticides to the leaf surface can increase the deposition of pesticides on crop leaves, extend the exposure time of pesticides, improve the utilization effect of pesticides. In addition, it can effectively prevent the active ingredients of pesticides from entering the environment and the ecosystem, further damaging the environment and the ecosystem, and posing potential hazards to non-target animals, plants, and human health.

[0004] As the target surface for pesticide droplets, the interfacial structure characteristics of plant leaves have an important influence on the wetting and adhesion behavior of droplets on the surface of target crops. The surface structure of plant leaves is complex and usually consists of an outer wax layer, an inner wax layer, and a cellulose layer composed of cell walls. Its interfacial structure not only plays a role in transporting nutrients and defending against pathogen attacks, but also has an important influence on the collision, wetting, and adhesion behavior of droplets on the surface of target crops. The outer wax layer, as the outermost structure of the target surface, determines the hydrophilicity and hydrophobicity of the leaf surface, enabling the crop to overcome physical and physiological problems generated by the surrounding environment.

[0005] The spiky particles have many spikes on their surface. This morphological structure can interact with the uneven micro-structure of the leaf surface to increase the retention of the particles on the leaf surface by increasing the contact area and friction coefficient between the particles and the leaf surface. Currently, the research on such spiky particles mainly focuses on the research of conductive polymers and catalysis, and there is no application of pesticide-loaded particles with a similar particle morphology in agriculture. At the same time, the reported spiky particles have the disadvantage of poor dispersibility, which also limits their further application. Summary of the Invention

[0006] Based on the above background art, the object of the present invention is to provide a drug-loaded particle with a spiky morphology capable of loading pesticides, its preparation method and application.

[0007] The object of the present invention is achieved by the following technical solutions:

[0008] On the one hand, the present invention provides a drug-loaded particle with a spiky morphology, and the drug-loaded particle includes a carrier with a spiky morphology and a loaded pesticide.

[0009] Based on the above technical solutions, further, the drug loading amount of the drug-loaded particle is 10-20%, and the particle size of the drug-loaded particle is between 200-800 nm.

[0010] On the other hand, the present invention provides a preparation method of the above-mentioned pesticide-loaded particle with a spiky morphology, and the preparation method mainly includes the following steps:

[0011] S1: Dissolve aniline in an acidic solution, add an acidic solution of a charged polymer, add an initiator, after the reaction is completed, dialyze and centrifuge the obtained reaction solution, and take the upper solution as a well-dispersed carrier particle solution;

[0012] S2: First dissolve the pesticide with an organic solvent, add the carrier particle solution prepared in S1, shake well and let stand, and filter and collect the drug-loaded particles to obtain.

[0013] Based on the above technical solutions, further, the acid in S1 is one or a combination of two or more of sulfuric acid, hydrochloric acid, and nitric acid; the charged polymer is one or a combination of two or more of polyethyleneimine, chitosan quaternary ammonium salt, and polyacrylic acid; the initiator is ammonium persulfate.

[0014] Based on the above technical solutions, further, the average molecular weight of the chitosan quaternary ammonium salt is 1000-10000, and the degree of substitution is 60-95%.

[0015] Based on the above technical solutions, further, the mass ratio of aniline, initiator, and charged polymer in S1 is 1:(0.5-2):(1-10).

[0016] Based on the above technical solutions, further, the concentration of the acid in S1 is 1-10 M; the final concentration of the charged polymer in the reaction system is 0.01-0.5 g / mL.

[0017] Based on the above technical solutions, further, the reaction conditions in S1 are to react at -15°C - 0°C for 12-48 h.

[0018] Based on the above technical solutions, further, the pesticide described in S2 is one or a combination of two or more of azoxystrobin, carbendazim, jinggangmycin, abamectin, difenoconazole, mandipropamid, and thiophanate-methyl.

[0019] Based on the above technical solutions, further, the organic solvent described in S2 is one or a combination of two or more of methanol, ethanol, and acetonitrile.

[0020] Based on the above technical solutions, further, the mass ratio of the carrier particles to the pesticide described in S2 is 1:1 to 4:1.

[0021] Based on the above technical solutions, further, the volume ratio of the organic solvent to the carrier particle solution in S2 is 1:4 to 2:1.

[0022] Based on the above technical solutions, further, the standing time in S2 is 6 to 12 h.

[0023] On the other hand, the present invention provides a pesticide composition comprising the above pesticide-loaded particles.

[0024] The present invention also provides the application of the above pesticide-loaded particles or pesticide composition in controlling crop pests and diseases.

[0025] The beneficial effects of the present invention compared with the prior art are as follows:

[0026] (1) The spiky pesticide-loaded polyaniline particles of the present invention have a particle size of 200 - 500 nm, with an obvious spiky morphology, good dispersibility, and a strong interaction with the micro-structure on the leaf surface. They can increase the contact area and friction coefficient between the pesticide-loaded particles and the leaf surface. Compared with traditional pesticide formulations, the adhesion amount can be increased by 25%, improving the utilization rate of pesticides.

[0027] (2) The present invention innovatively loads pesticides on particles with a spiky morphology. The drug loading amount can reach 17%. Compared with the application of conventional pesticides, it can reduce the diffusion, degradation, and loss of pesticides in the environment, while prolonging the pesticide efficacy period, reducing the number of pesticide applications, reducing the amount of pesticides used, and protecting the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention, the drawings related to the embodiments will be briefly introduced below.

[0029] Figure 1 It is a scanning electron micrograph of the carrier particles in Example 1.

[0030] Figure 2 It is a scanning electron micrograph of the carrier particles in Example 2.

[0031] Figure 3It is the result graph of the retention rate of the drug in the drug-loaded particles in Example 3 on the leaf surface.

[0032] Figure 4 It is the bright-field and dark-field microscope pictures of the fluorescently labeled particles in Example 3. Detailed implementation manners

[0033] The present invention will be described in detail below in conjunction with embodiments. However, the implementation manners of the present invention are not limited thereto. Obviously, the embodiments described below are only partial embodiments of the present invention. For those skilled in the art, without creative efforts, obtaining other similar embodiments will fall within the protection scope of the present invention.

[0034] Unless otherwise specified, the raw materials of the present invention are commercially available.

[0035] Example 1

[0036] A preparation method of a pesticide-loaded particle with a spiky morphology mainly includes the following steps:

[0037] S1: Prepare particles with a spiky morphology: First, prepare a 5M sulfuric acid solution. Weigh 0.25 g of ammonium persulfate (APS) and put it into 2 mL of the prepared sulfuric acid solution and stir to dissolve. Weigh 0.6 g of chitosan quaternary ammonium salt and add it to 5 mL of sulfuric acid solution and stir to dissolve at room temperature for 4 h. The dissolved APS solution and chitosan quaternary ammonium salt solution are placed in an environment at -10°C to cool. Measure 0.2 mL of aniline and dissolve it with 2.8 mL of sulfuric acid solution, stir until the white solid disappears, add it to the cooled chitosan quaternary ammonium salt solution and mix evenly. Finally, add the APS solution and react at -10°C for 24 h.

[0038] The prepared particle solution is first dialyzed in an environment at -4°C. When the pH is neutral, centrifuge at 1500 r / min for 5 min with a horizontal centrifuge, retain the upper liquid, add deionized water to the lower solid, shake and centrifuge again. The same operation is carried out multiple times until the upper liquid turns light green. The upper liquid obtained by centrifugation is filtered through a filter paper to remove the residual solid, and a well-dispersed carrier particle solution is obtained. Scanning electron microscope detection shows that the spiky morphology particle diagram is as Figure 1 shown. It can be seen from the figure that the particle surface has a needle-like structure and good dispersibility, and the particle size is about 500 nm.

[0039] S2: Prepare azoxystrobin-loaded particles: Weigh 5 mg of azoxystrobin, add 20 mL of methanol and dissolve it by ultrasonic treatment. Then add the spiky particle solution with a known concentration. The mass ratio of the carrier particles to the mass of azoxystrobin is 1:1. Make up the volume to 100 mL with deionized water and place it at room temperature for 12 h.

[0040] Example 2

[0041] The steps were the same as those in Example 1, except that the addition amount of quaternary ammonium chitosan was changed to 0.8 g, and the size of the particles obtained by scanning electron microscopy characterization was about 200 nm. The experimental results are as Figure 2 shown.

[0042] Example 3

[0043] Drug loading detection in Example 1: Take 10 mL of the drug-loaded particle solution prepared in S2, filter it with a filter membrane, and detect the filtrate by high-performance liquid chromatography at 254 nm. The drug loading of the drug-loaded particles was calculated to be 17%.

[0044] Example 4

[0045] Adhesion detection of the drug-loaded particle solution prepared in Example 1 on the leaf surface: Measure 100 mL of the drug-loaded particle solution of Example 1, filter and collect the drug-loaded particles, and prepare them into 2.5 mg / mL (calculated as azoxystrobin). Use a spray gun to evenly spray it on the cucumber leaves, and place the droplets on the surface of the dry leaves at room temperature. After drying, cut the cucumber leaves in half, cover a part of the cucumber leaves with plastic wrap, and rinse the other part with 100 mL of deionized water, and place the droplets at room temperature to dry. After calculating the leaf area with image J, cut the two parts of the cucumber leaves into pieces, soak them in dichloromethane for 12 h, then volatilize dichloromethane at room temperature, remove the cucumber leaves, add 0.2 mL of methanol to dissolve the solid for 1 h, detect the content of azoxystrobin by HPLC, calculate the retention rate of the drug-loaded particles on the leaves after rinsing with deionized water, and at the same time use azoxystrobin suspension concentrate and azoxystrobin water dispersible granules respectively according to the above method to detect the retention rate of azoxystrobin on the leaves. The experimental results are as Figure 3 shown. The retention rate of the drug-loaded particles in Example 3 on the leaves was 81.5%, which was significantly higher than that of azoxystrobin water dispersible granules by 22.67% and azoxystrobin suspension concentrate by 57%.

[0046] Example 5

[0047] Fluorescent labeling of spiky polyaniline particles: 1 mg each of 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC), N-hydroxysuccinimide (NHS), and rhodamine B (RB) was dissolved in 2 mL of water, activated in the dark for 5 h, centrifuged to remove the undissolved solids, and the supernatant was added to 8 mL of the carrier particle solution and reacted for 12 h. The solution was dialyzed for 3 days and observed with a fluorescence microscope. The experimental results are as Figure 4 shown. In the bright-field micrograph, black carrier particles can be seen. By comparing the bright-field and dark-field pictures, it can be found that most of the particles have fluorescence.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A drug-loaded granule, characterized in that, The drug-loaded particles include a carrier with a spiky morphology and a loaded pesticide; The drug loading of the drug-loaded particles is 10-20%, and the particle size of the drug-loaded particles is between 200-800 nm; The preparation method of the drug-loaded particles comprises the following steps: S1: Dissolve aniline in an acidic solution, add an acidic solution of a charged polymer, add an initiator, after the reaction is completed, dialyze and centrifuge the obtained reaction solution, and take the upper layer solution as a well-dispersed carrier particle solution; S2: First dissolve the pesticide in an organic solvent, add the carrier particle solution prepared in S1, shake well and let stand, filter and collect the drug-loaded particles to obtain; The charged polymer described in S1 is one or a combination of two or more of polyethyleneimine, quaternary ammonium salt of chitosan, and polyacrylic acid, and the initiator is ammonium persulfate; the mass ratio of aniline, initiator and charged polymer is 1:(0.5-2):(1-10); The pesticide described in S2 is one or a combination of two or more of azoxystrobin, carbendazim, jinggangmycin, abamectin, difenoconazole, mandipropamid, and thiophanate-methyl; the organic solvent is one or a combination of two or more of methanol, ethanol, and acetonitrile.

2. The drug-loaded particles according to claim 1, wherein The acid described in S1 is one or a combination of two or more of sulfuric acid, hydrochloric acid, and nitric acid; the average molecular weight of the quaternary ammonium salt of chitosan is 1000-10000, and the degree of substitution is 60-95%.

3. The drug-loaded particles according to claim 1, wherein The concentration of the acid described in S1 is 1-10M; the final concentration of the charged polymer in the reaction system is 0.01-0.5g / mL.

4. The drug-loaded particles according to claim 1, characterized in that, The reaction conditions in S1 are to react at -15°C - 0°C for 12-48h.

5. The drug-loaded particles according to claim 1, wherein The mass ratio of the carrier particles to the pesticide in S2 is 1:1~4:1; the volume ratio of the organic solvent to the carrier particle solution is 1:4~2:1; the standing time is 6~12h.

6. A pesticide composition comprising the drug-loaded particles according to claim 1 or 2.

7. Use of the drug-loaded particles according to claim 1 or 2 and the pesticide composition according to claim 6 in controlling crop pests and diseases.

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