Preparation method and application of intelligent polysaccharide-based nano reticular drug carrier microcapsule

Abstract

The invention discloses a preparation method of an intelligent polysaccharide-based nano reticular drug carrier microcapsule and application of the intelligent polysaccharide-based nano reticular drug carrier microcapsule in pesticide preparation. The preparation method comprises the following steps: dispersing nano-clay in water to prepare a water phase, and dissolving an active compound in a solvent to prepare an oil phase; adding the water phase into the oil phase to obtain Pickering emulsion; the preparation method comprises the following steps: adding Pickering emulsion, an anionic polysaccharide aqueous solution and a cationic polysaccharide aqueous solution into the Pickering emulsion, carrying out cross-linking reaction for multiple times, and stirring to obtain the polysaccharide-based nano reticular drug carrier microcapsule. The preparation method is simple and convenient, can be completed only through two steps of emulsification and crosslinking, and is efficient and rapid in preparation process. And addition of a synthetic emulsifier or a small molecular surfactant is avoided while high-efficiency preparation is realized. The method disclosed by the invention is simple and low in cost, and the obtained drug-loaded microcapsule has relatively high encapsulation efficiency and good controlled-release and slow-release performance, and has a wide application prospect in the field of modern agriculture.

Description

Technical Field

[0001] The present invention relates to a preparation method and application of an intelligent polysaccharide-based nano-network drug carrier microcapsule, belonging to the technical field of drug carriers. Background Art

[0002] In agricultural production, emulsifiable concentrates are favored due to their wide applicability and simple preparation process. This preparation mainly consists of the original pesticide, solvent, and emulsifier, and can be completed by stirring in a reaction kettle. Due to its low cost and remarkable effect, emulsifiable concentrates occupy a large share in the market. However, during the preparation process of emulsifiable concentrates, to ensure their stability, a certain amount of emulsifier is usually added. Although these emulsifiers help improve the stability of emulsifiable concentrates, they may also bring a series of problems. On the one hand, they may cause environmental pollution; on the other hand, long-term exposure may also have an adverse impact on human health. In addition, the use of emulsifiers may also increase production costs. In recent years, the agricultural science and technology community has begun to explore the use of new materials to replace traditional emulsifiers to reduce environmental pollution and human health risks. Among them, materials such as halloysite and diatomite are used to prepare Pickering emulsions, which not only have good stability but also can reduce the impact on the environment and human body to a certain extent.

[0003] In the fields of medicine, cosmetics, food, etc., it is a highly promising strategy to use a variety of organic and inorganic materials to construct Pickering emulsions to achieve the controlled release and sustained release functions of drugs. Pickering emulsions are emulsions stabilized by solid particles, which can be organic or inorganic materials such as nano-silica, clay, cellulose, etc. Through reasonable selection and design, these materials can regulate the stability, release rate, and biocompatibility of the emulsion, so as to meet the specific requirements of different fields. Chinese Patent Application CN118562152A discloses a preparation method of Pickering emulsion. Specifically, the electrostatic self-assembly of cellulose nanocrystals and amino-terminated polymer ligands at the oil-water interface can better stabilize aromatic compounds with different structures. This self-assembly process is driven by electrostatic forces and forms a stable and controllable emulsion, overcoming the defect of poor stability of existing aroma compound emulsions, and the preparation method is simple and fast. Chinese Patent Application CN118044507A provides a Pickering emulsion stabilized by phytic acid-modified starch and protein composite colloidal particles. The preparation of this Pickering emulsion can be achieved only through one-step emulsification, which is simple, convenient, time-consuming, and energy-consuming; while efficiently preparing, it avoids introducing synthetic emulsifiers or small molecule surfactants, and also greatly reduces the protein content required in the Pickering emulsion. The obtained Pickering emulsion has good nutrient release characteristics and can be applied to the fields of medicine, cosmetics, food, etc. However, the preparation method of the Pickering emulsion in the patent application CN118562152A mainly maintains the stability of the emulsion through the electrostatic self-assembly of cellulose nanocrystals and amino-terminal polymer ligands at the oil-water interface. Although this method achieves the stability of the emulsion to a certain extent, its production process is relatively complex, the components used are not green and environmentally friendly enough, and the functional efficiency is also relatively single. Therefore, there is an urgent need to develop a green, low-cost, multi-functional, easily deformable, and excellent stability Pickering emulsion microcapsule system to meet the needs of green and efficient prevention and control of harmful organisms. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: how to efficiently encapsulate the active ingredients of pesticides to achieve the precise delivery of pesticides and effectively control crop diseases and pests.

[0005] To solve the above technical problems, the technical solution of the present invention is: to provide a preparation method of an intelligent polysaccharide-based nano-network drug carrier microcapsule, including the following steps:

[0006] Step 1): Preparation of Pickering emulsion stabilized by nano-clay: The Pickering emulsion is composed of an aqueous phase and a solvent oil. The specific method is as follows:

[0007] Preparation of the aqueous phase: Disperse nano-clay in deionized water at a ratio of 3 mg: 100 L;

[0008] Preparation of the oil phase: Dissolve the technical material in a solvent at a ratio of 10 mg: 30 L;

[0009] Add the aqueous phase to the oil phase at a volume ratio of 7:3, and shear and mix under a homogenizing shear machine to obtain a Pickering emulsion stabilized by nano-clay;

[0010] Step 2): Preparation of the multi-layer nano-networked capsule shell: Crosslink an anionic polysaccharide aqueous solution and a cationic polysaccharide aqueous solution multiple times in sequence to form a multi-layer capsule shell. The specific method is as follows:

[0011] Dissolve the anionic polysaccharide in deionized water at a ratio of 0.1 - 10 mg: 100 L to prepare an anionic polysaccharide aqueous solution;

[0012] Dissolve the cationic polysaccharide in deionized water at a ratio of 0.01 - 5 mg: 100 L to prepare a cationic polysaccharide aqueous solution;

[0013] Add the Pickering emulsion, the anionic polysaccharide aqueous solution, and the cationic polysaccharide aqueous solution to the Pickering emulsion in a mass ratio of 1 - 9: 0.05 - 10: 0.05 - 10 in the order of first adding the anionic polysaccharide aqueous solution and then adding the cationic polysaccharide aqueous solution, and stir to obtain a polysaccharide-based nano-network drug carrier microcapsule.

[0014] Preferably, the nano-clay is at least one of attapulgite, kaolin, halloysite, and bentonite.

[0015] Preferably, the solvent is at least one of n-hexane, methanol, cyclohexanone, dichloromethane, toluene, and xylene.

[0016] Preferably, the technical material contains a pesticidal active ingredient, including a bactericide or an insecticide.

[0017] More preferably, the bactericide includes at least one of tebuconazole, pyraclostrobin, iprodione, boscalid, and prothioconazole; the insecticide includes at least one of lambda-cyhalothrin, emamectin benzoate, clothianidin, and thiamethoxam.

[0018] Preferably, the cationic polysaccharide includes at least one of alginate, carrageenan, pectin, xanthan gum, sodium lignosulfonate, and sodium alkali lignosulfonate.

[0019] Preferably, the cationic polysaccharide includes at least one of chitosan, chitosan oligosaccharide, guar gum, chitin, and water-soluble protein.

[0020] The present invention also provides the application of the intelligent polysaccharide-based nano-networked drug carrier microcapsule prepared by the above preparation method in the preparation of pesticides.

[0021] The present invention uses clay to prepare emulsions, demonstrating significant advantages in many aspects. First of all, the clay raw material has fine particles, is easy to obtain, and comes from nature (such as aluminosilicate minerals), featuring economic practicality and environmental friendliness. Clay not only has strong adsorption capacity and modifiability, but also can stabilize emulsion droplets and prevent stratification. In addition, through chemical modification, clay can be transformed into amphiphilic materials, further enhancing the stability of the emulsion. The rough structure on the clay surface enables it to firmly adhere to the plant leaf surface, increasing the residence time of the pesticide active ingredient on the leaf surface while reducing environmental pollution. Most importantly, as a natural mineral raw material, the use of clay is safe and environmentally friendly, and no emulsifiers and surfactants need to be added during the preparation process, reducing environmental risks. The natural clay surface has rough and porous characteristics, which enable it to effectively adsorb polysaccharide molecules. In the aqueous phase, anionic and cationic polysaccharide molecules spontaneously crosslink through electrostatic interaction and hydrogen bonding to form a double-network hybrid gel layer. This gel layer coats the clay-based stable water-oil interface to form a nano-network capsule shell. Through multiple crosslinkings, this capsule shell can form a multi-layer structure, not only significantly improving the encapsulation rate of the pesticide active ingredient, but also enabling intelligent release according to environmental stimuli (such as pH, temperature, etc.). The reinforced coating of the polysaccharide hydrogel layer endows the microcapsule shell with excellent mechanical strength and deformation ability. This enables the microcapsule to transform from a "spherical" shape to a "pancake" shape on the crop leaf surface, significantly enhancing the leaf surface adhesion of the microcapsule and improving its ability to resist rain erosion. The flexibility and adjustability of the gel network enable it to adapt to the morphology and surface structure of different leaf surfaces, increasing the contact area between the microcapsule and the plant surface, thereby improving the residence time and coverage effect of the drug. In addition, the hydrogel network structure can form a self-repairing and protective layer under ultraviolet light irradiation, further enhancing the ultraviolet resistance of the microcapsule and preventing the drug components from degrading or becoming ineffective in sunlight. Therefore, the special structure of the gel layer not only optimizes the release and delivery of the drug, but also enhances the environmental adaptability of the microcapsule, providing technical support for achieving more efficient pesticide control and long-term protection.

[0022] This method aims to overcome problems such as large amounts of surfactants used in traditional formulations, difficult degradation of auxiliaries, and high costs, and provides a more environmentally friendly solution. The drug carrier uses clay with a nano-network structure as a stabilizer. By introducing polysaccharide molecules with opposite charges at the oil-water interface and utilizing layer-by-layer self-assembly technology and hydrogen bonding to promote the polymerization reaction, a Pickering emulsion microcapsule system with a multi-layer polymer shell is formed, thereby efficiently encapsulating the active ingredient of the pesticide. The microcapsules obtained by this preparation method not only have excellent stability but also possess intelligent controlled-release characteristics, and can respond to environmental stimuli (such as pH, temperature, light, etc.) to achieve precise release of the pesticide. Through the reinforcement coating of the polysaccharide hydrogel layer, the outer shell of the microcapsule not only has good mechanical strength and deformation ability, enabling it to change from a "spherical" shape to a "pancake" shape on the crop leaf surface, significantly enhancing the leaf surface adhesion of the microcapsule, but also improving the ability to resist rain erosion. This deformation ability stems from the flexibility and adjustability of the gel network structure, which can effectively adapt to different leaf surface morphologies and surface structures, increase the contact area between the microcapsule and the plant surface, thereby increasing the residence time and coverage effect of the drug. In addition, the structure of the hydrogel network can form a self-repairing and protective layer under ultraviolet light irradiation, further enhancing the resistance of the microcapsule to ultraviolet light and preventing the degradation or inactivation of the drug components under light. Therefore, the special structure of the gel layer not only optimizes the release and delivery of the drug but also enhances the environmental adaptability of the microcapsule, providing a technical guarantee for achieving more efficient pesticide control and long-term protection. In addition, by finely regulating the composition and wall void structure of the polysaccharide-based nano-network shell, the leakage of pesticide components can be effectively prevented, thereby further enhancing the biocompatibility and environmental friendliness of the microcapsule. The microcapsule formulation provided by the present invention has significant environmentally friendly advantages and has broad application prospects in precise pesticide delivery and environmental protection.

[0023] The present invention uses clay with a nano-network structure as a stabilizer. By introducing polysaccharide molecules with opposite charges at the oil-water interface and utilizing layer-by-layer self-assembly technology and hydrogen bonding to promote the polymerization reaction, a Pickering emulsion microcapsule system with a multi-layer polymer shell is formed. Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. Improve the effective utilization rate of pesticides: Using the Pickering emulsion as a template, a polysaccharide-based shell is coated layer by layer on the water-oil interface of the emulsion through electrostatic self-assembly technology. The shell layer can also achieve intelligent release of pesticides according to environmental stimuli (such as pH, temperature, light, etc.).

[0025] 2. The preparation process is simple: During the preparation process, there is no need to modify the materials. It can be prepared only through one-step emulsification and simple electrostatic self-assembly. The production cost is reduced and the preparation efficiency is improved.

[0026] 3. Environmental advantages: The raw materials required for the clay-stabilized polysaccharide drug-loaded microcapsules are all natural degradable materials. Emulsifiers and surfactants are not added during the preparation process, which not only reduces the environmental pressure but also enhances the safety of chemical control for the ecological environment.

[0027] In summary, the present invention provides a method for preparing a nano-clay-stabilized polysaccharide-based drug-loaded microcapsule. The preparation process of the drug-loaded microcapsule is simple and convenient, and can be completed only through two steps of emulsification and cross-linking, with high efficiency and speed. While achieving high-efficiency preparation, the addition of synthetic emulsifiers or small molecule surfactants is avoided. The method of the present invention is simple and low-cost, and the obtained drug-loaded microcapsules have a high encapsulation rate and good controlled and sustained release properties, showing broad application prospects in the field of modern agriculture. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is the cumulative release experimental graph of Examples 1-4;

[0029] Figure 2 It is the digital graph of the wheat scab control experiment of the prothioconazole technical and prothioconazole commercial agent in Examples 1-4;

[0030] Figure 3 It is the bar graph of the growth inhibition rate of the prothioconazole technical and prothioconazole commercial agent in Examples 1-4;

[0031] Figure 4 It is the digital graph of the product obtained in Example 1;

[0032] Figure 5 It is the microscopic graph of the product obtained in Example 1 stored at room temperature;

[0033] Figure 6 It is the bar graph of the product obtained in Example 1 stored at room temperature;

[0034] Figure 7 It is the cumulative release line graph of the product obtained in Example 1;

[0035] Figure 8 It is the retention bar graph of the prothioconazole technical and prothioconazole commercial agent in Example 1;

[0036] Figure 9 It is the bar graph of the leaf surface contact angle of the prothioconazole technical and prothioconazole commercial agent in Example 1;

[0037] Figure 10 It is the digital graph of the leaf surface contact angle of the prothioconazole technical and prothioconazole commercial agent in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] To make the present invention more obvious and understandable, preferred embodiments are described in detail below in conjunction with the accompanying drawings.

[0039] Example 1

[0040] Dissolve a certain mass of tebuconazole technical in a certain volume of cyclohexanone to prepare a solution with a mass concentration of 1 mg / L. At the same time, take a certain mass of attapulgite and disperse it in an aqueous solution to prepare an aqueous phase with a mass concentration of 0.3 mg / L. Then, select 1% (m / v) sodium alginate aqueous solution as the anionic ionic polysaccharide aqueous solution and 1% (m / v) chitosan oligosaccharide aqueous solution as the cationic polysaccharide aqueous solution. Next, add the aqueous phase and the oil phase to a container in a volume ratio of 7:3 and shear at a speed of 10,000 revolutions per minute for 3 minutes to form a clay Pickering emulsion. After that, the emulsion is first mixed and stirred with 1% (m / v) sodium alginate aqueous solution in a volume ratio of 8:2 for 30 minutes, and then mixed and stirred with 1% (m / v) chitosan oligosaccharide aqueous solution in a volume ratio of 9:1 to prepare a layer of capsule shell structure. Finally, by repeating the above process, that is, adding sodium alginate and chitosan oligosaccharide in the same proportion in sequence again for reaction, two more layers can be further constructed, and repeating again can prepare a three-layer capsule shell.

[0041] Example 2

[0042] In the process of preparing the clay Pickering emulsion, first prepare the oil phase: dissolve a certain mass of tebuconazole technical in a certain volume of cyclohexanone to prepare a solution with a mass concentration of 1 mg / L. Then, prepare the aqueous phase: take a certain mass of attapulgite and disperse it in water to prepare an aqueous phase with a mass concentration of 0.3 mg / L. Next, add the aqueous phase and the oil phase to a container in a volume ratio of 7:3 and shear at a speed of 10,000 revolutions per minute for 3 minutes to prepare the clay Pickering emulsion.

[0043] Example 3

[0044] In the process of preparing the clay Pickering emulsion and its capsule shell structure, first prepare the oil phase: dissolve a certain mass of tebuconazole technical in a certain volume of cyclohexanone to prepare a solution with a mass concentration of 1 mg / L. Then, prepare the aqueous phase: take a certain mass of attapulgite and disperse it in water to prepare an aqueous phase with a mass concentration of 0.3 mg / L. At the same time, prepare the anionic polysaccharide aqueous solution and the cationic polysaccharide aqueous solution, and select 1% (m / v) sodium alginate aqueous solution and 1% (m / v) chitosan oligosaccharide aqueous solution respectively. Next, add the aqueous phase and the oil phase to a container in a volume ratio of 7:3 and shear at a speed of 10,000 revolutions per minute for 3 minutes to prepare the clay Pickering emulsion. Next, mix and stir this clay Pickering emulsion with 1% (m / v) sodium alginate aqueous solution in a volume ratio of 8:2 for 30 minutes, and then mix and stir with 1% (m / v) chitosan oligosaccharide aqueous solution in a volume ratio of 9:1. Through this series of steps, a layer of capsule shell structure can be prepared.

[0045] Example 4

[0046] Take a certain mass of tebuconazole technical and dissolve it in cyclohexanone to prepare a solution with a mass concentration of 1 mg / L. Then, disperse a certain mass of attapulgite in water to prepare a suspension with a mass concentration of 0.3 mg / L. Next, select an aqueous sodium alginate solution with a mass fraction of 1% (m / v) and an aqueous chitosan oligosaccharide solution with a mass fraction of 1% (m / v) as the capsule shell layer. Subsequently, add the above-mentioned aqueous phase and oil phase to a container in a volume ratio of 7:3 and shear at a speed of 10,000 revolutions per minute for 3 minutes to prepare a clay Pickering emulsion. Then, mix the emulsion with an aqueous sodium alginate solution of 1% (m / v) in a volume ratio of 8:2 and stir for 30 minutes, and then mix it with an aqueous chitosan oligosaccharide solution of 1% (m / v) in a volume ratio of 9:1 and stir to form a layer of capsule shell. Finally, add sodium alginate and chitosan oligosaccharide again in the above volume ratio sequence for reaction to prepare a structure with two layers of capsule shells.

[0047] Among Examples 1-4, the encapsulation efficiency of the polysaccharide microcapsules prepared in Example 1 is the highest and the control effect on Gibberella zeae is the best. The performance of the polysaccharide microcapsules in Example 1 was measured.

[0048] (1) Experimental method

[0049] Determination of encapsulation efficiency: The encapsulation efficiency of the preparations prepared in Examples 1-4 was measured. Respectively take 0.1 g of the preparations prepared in Examples 1-4, dissolve and make up to 10 mL with deionized water, and then add 3 mL of n-hexane. Place this system on a rolling bed and rotate it at 60 rpm / min for 5 min. Take down this system and pipette 0.5 mL of the n-hexane layer. After nitrogen blowing, redissolve it with an equal volume of methanol, filter through a membrane and inject it into the liquid phase for determination. Record the mass of free tebuconazole as M_free. Then take 0.1 g of the emulsions prepared in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3, dissolve and make up to 10 mL with methanol, place it in an ultrasonic bath and ultrasonically extract for 20 min, take 0.5 mL, filter through a membrane and inject it into the liquid phase for determination. Record the total amount of tebuconazole as M_total. Calculate the encapsulation efficiency with the following formula:

[0050]

[0051] (2) Data analysis

[0052] The test results are as Figure 1 shown. It can be seen that the encapsulation efficiency of the polysaccharide microcapsules in Example 1 is the highest at 76.3%, indicating that the polysaccharide microcapsules in Example 1 have good encapsulation performance.

[0053] Antibacterial experiments on the preparation of microcapsules from tebuconazole technical and tebuconazole commercial formulations in Examples 1-4

[0054] (1) Experimental method

[0055] The growth rate method was used to determine the antibacterial activities of Examples 1-4, tebuconazole technical, and tebuconazole commercial formulation (active ingredient mass content 12.5%) against Gibberella zeae. Mycelia with a diameter of 5 mm were inoculated at the center of a potato dextrose agar medium. Examples 1 and Comparative Example 1 were mixed with a sterile molten medium to reach the required concentrations (0.5 mg / L, 1 mg / L, 2.5 mg / L, 5 mg / L, 10 mg / L), and at the same time, sterile deionized water was used as the control group. According to the growth rate of the mycelia in the control group, it was cultured at 25°C ± 2 for one week, the mycelial diameter was measured, and each treatment group was repeated 3 times. The antibacterial activity was expressed as the growth inhibition percentage (%). The calculation was as follows:

[0056]

[0057] (2) Data analysis

[0058] As shown by Figures 2-3 the polysaccharide microcapsules prepared in Example 1 of the present invention can effectively inhibit Fusarium graminearum.

[0059] Physicochemical properties of the polysaccharide microcapsules in Example 1

[0060] (1) Experimental method

[0061] Observation of the Pickering emulsion microstructure: The emulsion prepared in Example 1 was observed under an optical microscope. 20 μL of the Pickering emulsion prepared in Example 1 was dropped on a glass slide and observed under a 20-fold microscope.

[0062] Storage stability: Example 1 was stored at 25°C, and it was observed under an optical microscope every day and the particle size was measured using a micron laser particle size analyzer.

[0063] (2) Data analysis

[0064] As shown by Figures 4-6 it can be seen that the polysaccharide microcapsules prepared in Example 1 have good stability.

[0065] Cumulative release experiment of the polysaccharide microcapsules in Example 1

[0066] (1) Experimental method

[0067] The release of the polysaccharide microcapsules prepared in Example 1 was measured. 0.1 g of the polysaccharide microcapsules prepared in Example 1 was diluted and fixed to 20 mL with aqueous solutions with pH values of 5, 7, and 9 respectively, and then 10 mL of n-hexane was added. 0.1 mL of the n-hexane layer was taken at a specified time period. After the n-hexane taken out was blown with nitrogen, it was redissolved with the same volume of methanol and filtered through a membrane for liquid phase detection. The cumulative release rate was calculated using the following formula.

[0068]

[0069] (2) Data analysis

[0070] The cumulative release three-line table of the product obtained in Example 1 is shown in Table 1 as follows.

[0071] Table 1

[0072]

[0073] From Table 1, Figure 7 it can be seen that the polysaccharide microcapsules prepared in Example 1 have good controlled-release and sustained-release effects.

[0074] Leaf surface wettability experiment of polysaccharide microcapsules in Example 1

[0075] (1) Experimental method

[0076] Leaf surface retention experiment: Wheat leaves in the vigorous growth period were made into circular shapes with a diameter of 1 cm using a hole punch. The leaves were respectively immersed in the same mass of tebuconazole technical, tebuconazole commercial agent (active ingredient mass content 12.5%), and the aqueous solution of Example 1. The concentrations of both were the field recommended concentrations. After taking them out for 10 s until no more liquid droplets dripped from the leaves. Record the mass change of the liquid in the beaker before and after taking out the leaves. Calculate the leaf retention amount using the following formula:

[0077]

[0078] Among them, W1 is the final weight obtained by weighing the beaker containing the immersed leaves; W0 is the initial weight of the leaves; S is the surface area of the wheat leaves.

[0079] Leaf surface contact angle experiment: Wheat leaves in the vigorous growth period in the greenhouse were collected, gently rinsed with deionized water to remove various floating dust on the leaf surface, taking care not to damage the leaf structure and morphology. After natural drying, a part between the main vein and the leaf edge was cut with scissors as the test sample, and the test sample was fixed flat on the glass slide with double-sided tape. Then the prepared leaf sample was placed on the stage of the contact angle measuring instrument, and the height of the stage was adjusted so that the glass slide could completely appear in the screen field of view. Then, 5 μL of deionized water or the sample to be tested in the micro syringe was gently dropped onto the soybean leaf according to the set parameters. When the liquid droplet state on the leaf surface was stable, quickly capture the image and record the contact angle values of the tebuconazole commercial agent (active ingredient mass content 12.5%) and the aqueous solution of Example 1 with the concentration of the field recommended dose.

[0080] (2) Data analysis

[0081] From Figures 8-10 it can be seen that the polysaccharide microcapsules prepared in Example 1 have good wettability on the wheat leaf surface.

Claims

1. A method for preparing smart polysaccharide-based nano-network drug carrier microcapsules, characterized in that: The following steps are involved: Step 1): Preparation of nanoclay-stabilized Pickering emulsion: The Pickering emulsion is composed of an aqueous phase and solvent oil, and the specific method is as follows: Preparation of aqueous phase: Nanoclay was dispersed in deionized water at a ratio of 3 mg:100 L; Preparation of oil phase: Dissolve the original drug in the solvent at a ratio of 10 mg:30 L; The water phase was added to the oil phase in a volume ratio of 7:3, and sheared and mixed under a homogenizing shearing machine to obtain a nanoclay-stabilized Pickering emulsion; Step 2): Preparation of multi-layer nano-net capsule shell: Anionic polysaccharide aqueous solution and cationic polysaccharide aqueous solution are subjected to multiple cross-linking reactions in sequence to form a multi-layer capsule shell. The specific method is as follows: Dissolve anionic polysaccharide in deionized water at a ratio of 0.1-10 mg:100 L to prepare anionic polysaccharide aqueous solution; Dissolve the cationic polysaccharide in deionized water at a ratio of 0.01-5 mg:100 L to prepare a cationic polysaccharide aqueous solution; Pickering emulsion, anionic polysaccharide aqueous solution, and cationic polysaccharide aqueous solution are mixed in a mass ratio of 1-9:0.05-10: 0.05-10 is added into the Pickering emulsion according to the steps of first dropping anionic polysaccharide aqueous solution and then dropping cationic polysaccharide aqueous solution, and stirred to obtain polysaccharide-based nanonet drug carrier microcapsules.

2. The method for preparing the smart polysaccharide-based nano-network drug carrier microcapsule according to claim 1, characterized in that: The nano clay is at least one of attapulgite, kaolin, halloysite and bentonite.

3. The method for preparing the smart polysaccharide-based nano-network drug carrier microcapsule according to claim 1, characterized in that: The solvent is at least one of n-hexane, methanol, cyclohexanone, dichloromethane, toluene and xylene.

4. The method for preparing the smart polysaccharide-based nano-network drug carrier microcapsule according to claim 1, characterized in that: The technical material contains active ingredients of pesticides, including fungicides or insecticides.

5. The method for preparing the smart polysaccharide-based nano-network drug carrier microcapsule according to claim 4, characterized in that: The fungicide includes at least one of tebuconazole, pyraclostrobin, iprodione, boscalid and prothioconazole; the insecticide includes at least one of cyhalothrin, emamectin benzoate, clothianidin and thiamethoxam.

6. The method for preparing the smart polysaccharide-based nano-network drug carrier microcapsule according to claim 1, characterized in that: The cationic polysaccharide comprises at least one of alginate, carrageenan, pectin, xanthan gum, sodium lignin sulfonate and alkali sodium lignin sulfonate.

7. The method for preparing the smart polysaccharide-based nano-network drug carrier microcapsule according to claim 1, characterized in that: The cationic polysaccharide comprises at least one of chitosan, chitosan oligosaccharide, guar gum, chitin and water-soluble protein.

8. Use of the smart polysaccharide-based nano-network drug carrier microcapsules prepared by the preparation method according to any one of claims 1 to 7 in the preparation of pesticides.

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