Chitosan-based drug-loading material and application thereof in pesticide preparation
By cross-linking and gelling chitosan-based drug-loaded materials, the problem of insufficient adhesion of chitosan-based drug-loaded materials in high-humidity environments was solved, achieving efficient utilization of pesticides and effective control of downy mildew.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BENGBU GERUN BIOTECHNOLOGY CO LTD
- Filing Date
- 2026-03-11
- Publication Date
- 2026-06-12
AI Technical Summary
Existing chitosan-based pesticide-loaded materials have insufficient adhesion in high-humidity environments, leading to easy pesticide loss and making it difficult to meet the pest control needs of short-harvest crops.
By cross-linking carboxymethyl chitosan, mesoporous particle-nanocellulose hybrid fibers, and low-methoxyl pectin with humic acid to form a gel film, the adhesion and stability of pesticides can be improved when combined with calcium chloride solution for spraying.
It enhances pesticide utilization, reduces the number of re-spraying applications, improves the production efficiency of short-harvest crops, and effectively inhibits the occurrence of downy mildew.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of pesticide loading material technology, specifically a chitosan-based loading material and its application in pesticide formulations. Background Technology
[0002] Downy mildew is an obligate parasitic disease caused by *Peronospora* fungi, a type of fungus in the class Oomycetes of the subphylum Oomycetes. It can affect a variety of crops, including cucumbers, grapes, cabbage, sunflowers, and peppers. In the early stages, small, pale green, water-soaked spots appear on the leaves, which then expand into polygonal or irregular yellow spots restricted by leaf veins. Under high humidity, a white to grayish-white, frosty mold layer appears on the corresponding areas of the leaf underside. Downy mildew is particularly prevalent in greenhouse cultivation of vegetables like cucumbers, where the high humidity creates an environment conducive to its development. Greenhouse downy mildew is characterized by a short incubation period, rapid onset, and severe damage, leading to rapid yellowing and death of leaves, and even complete leaf drop, resulting in a significant decrease in yield and quality.
[0003] Commonly used chemical agents for downy mildew control include chlorothalonil smoke agents and cymoxanil aqueous solutions. However, pesticide smoke agents generate smoke at high temperatures, posing safety hazards when used in greenhouses, and the smoke residue can easily pollute the environment, leading to pathogen resistance. Aqueous pesticides, on the other hand, have short-lasting effects, making disease rebound easy. With the development of pesticide-loaded materials, research has found that chitosan molecules contain a large number of amino and hydroxyl groups, which can bind to pesticide molecules through electrostatic and hydrogen bonding forces, achieving slow-release and high-efficiency effects with low dosage.
[0004] Chinese patent application CN109929057A discloses pesticide controlled-release coating materials, drug-loaded nanomicelles, and their preparation methods. These materials utilize amphiphilic chitosan derivatives to self-assemble into 100-2500 nm spherical micelles, achieving the encapsulation of hydrophobic pesticides. This provides excellent protection and a barrier effect for the encapsulated drug, thus achieving a sustained-release function. However, similar solutions exhibit limited adhesion of spherical micelles after foliar application, leading to droplets easily bouncing off during spraying. Especially in high-humidity greenhouse environments, the micelles are more prone to loss with dew droplets, resulting in a significantly shortened effective period and requiring multiple re-sprays. This is difficult to match with the tight production schedule of short-harvest crops such as cucumbers. Summary of the Invention
[0005] The purpose of this invention is to provide a chitosan-based drug-loaded material and its application in pesticide formulations. Firstly, carboxymethyl chitosan, mesoporous particles-nanocellulose hybrid fibers, and low-methoxyl pectin are appropriately cross-linked with humic acid via hydrogen bonding to improve the stability of the drug-loaded material. After reconstitution and formulation into a drug-loaded pesticide formulation, it is sprayed simultaneously with a calcium chloride solution. Through ionic coordination cross-linking, carboxymethyl chitosan and other components rapidly form a gel film that adheres to the leaves, helping to improve pesticide utilization, reduce or avoid re-spraying, and improve the production efficiency of short-harvest crops such as cucumbers.
[0006] The objective of this invention can be achieved through the following technical solutions:
[0007] A chitosan-based drug delivery material is prepared by centrifugation and freeze-drying of chitosan-based hydrosol. The chitosan-based hydrosol comprises the following raw materials in the indicated mass percentages:
[0008] Mesoporous particles-nanocellulose hybrid fibers 0.6%-0.8%, cellulose acetate short nanofibers 0.15%-0.2%, carboxymethyl chitosan 0.1%-0.12%, low-methoxyl pectin 0.1%-0.12%, humic acid 0.01%-0.015%, with the balance being deionized water.
[0009] Furthermore, the preparation method of chitosan-based drug-loaded materials is as follows:
[0010] Mesoporous particles-cellulose nanofiber hybrids and cellulose acetate short nanofibers were mixed and ultrasonically dispersed in 50 times their mass of deionized water for 10-20 min. The mixture was then added to a stirred tank. Carboxymethyl chitosan and low-methoxyl pectin were dissolved in 100 times their mass of deionized water and added to the stirred tank. The mixture was stirred at 40-50℃ and 300-500 r / min for 30-60 min. Humic acid was then dissolved in 100 times its mass of deionized water and added to the stirred tank. Deionized water was added as needed, and the mixture was stirred for another 20-30 min to obtain a chitosan-based hydrosol.
[0011] The preparation method of chitosan-based drug-loaded materials is more specifically as follows:
[0012] 0.6wt%-0.8wt% of mesoporous particles-nanocellulose hybrid fibers and 0.15wt%-0.2wt% of cellulose acetate short nanofibers were mixed and ultrasonically dispersed in 50 times their mass of deionized water for 10-20 min. The mixture was then transferred to a stirred tank. 0.1wt%-0.12wt% of carboxymethyl chitosan and 0.1wt%-0.12wt% of low-methoxyl pectin were dissolved in 100 times their mass of deionized water and added to the stirred tank. The mixture was stirred at 40-50℃ and 300-500 r / min for 30-60 min. 0.01wt%-0.015wt% of humic acid was dissolved in 100 times its mass of deionized water and added to the stirred tank. The mixture was then brought to 100wt% with deionized water and stirred for another 20-30 min to obtain the chitosan-based hydrosol.
[0013] Furthermore, the centrifugation conditions for chitosan-based hydrosols are: 8000 r / min for 10-15 min.
[0014] Furthermore, the preparation method of mesoporous particle-cellulose nanofiber hybrid fiber is as follows:
[0015] Step 1: Using hexadecyltrimethylammonium bromide as a structure directing agent and 1,2-bis(triethoxysilyl)ethane as a silicon source, mesoporous nano-silica was grown in situ on one side of nano-copper oxide to prepare mesoporous nano-silica-copper oxide composite particles.
[0016] Step 2: Using dibutyltin dilaurate as a catalyst, propyltriethoxysilane isocyanate is grafted onto the surface of nanocellulose fibers via carbamylation to obtain modified nanocellulose fibers. Then, the grafted siloxane is hydrolyzed and bonded to the hydroxyl groups of the mesoporous nanosilica-copper oxide composite particles to prepare mesoporous particle-nanocellulose hybrid fibers.
[0017] Furthermore, the mesoporous nano-silica-copper oxide composite particles were prepared through the following steps:
[0018] Nano-copper oxide, hexadecyltrimethylammonium bromide, 25wt% ammonia, anhydrous ethanol, and deionized water were added to a reaction vessel and stirred at 35-40℃ and 300-500 rpm for 30-40 min, followed by ultrasonic dispersion for 10-15 min. Then, 1,2-bis(triethoxysilyl)ethane was added to the reaction vessel and stirring was continued for 4-5 h. The mixture was centrifuged at 8000 rpm for 10-15 min. The precipitate was washed sequentially with acid and 90%wt ethanol aqueous solution, and then vacuum dried at 60-80℃ to obtain mesoporous nano-silica-copper oxide composite particles.
[0019] The acid solution is prepared by mixing 36wt% hydrochloric acid and anhydrous ethanol at a volume ratio of 1:500.
[0020] The acid wash should be performed 3-5 times, and the ethanol-water solution wash should be performed until the final wash solution is neutral.
[0021] The ratio of nano-copper oxide, hexadecyltrimethylammonium bromide, ammonia, anhydrous ethanol, deionized water, and 1,2-bis(triethoxysilyl)ethane is 40-50 mg: 1-1.2 g: 30-35 mL: 35-40 mL: 50-60 mL: 32-40 μL.
[0022] Furthermore, the modified cellulose nanofibers are prepared through the following steps:
[0023] The IPTS solution was transferred to a reaction vessel, and nanocellulose fibers and dibutyltin dilaurate were added. The mixture was stirred at 60-70℃ and 200-300 r / min for 4-4.5 h. After filtration, the filter cake was washed 2-3 times with ethyl acetate and freeze-dried to obtain modified nanocellulose fibers.
[0024] The IPTS solution is prepared by dissolving propyltriethoxysilane isocyanate (IPTS) in dimethyl sulfoxide.
[0025] The ratio of IPTS solution, nanocellulose fiber, and dibutyltin dilaurate is 8-10 mL: 1 g: 0.11-0.13 g.
[0026] Furthermore, the mesoporous particle-cellulose nanofiber hybrid fiber was prepared through the following steps:
[0027] Mesoporous nano-silica-copper oxide composite particles and deionized water were added to a reaction vessel and ultrasonically dispersed for 10-20 min. Then, modified nanocellulose fibers were added to the reaction vessel and stirred at 80-85℃ for 8-10 h. After naturally cooling to room temperature, the mixture was centrifuged and filtered. The filter cake was washed 2-3 times with deionized water and freeze-dried to obtain mesoporous particle-nanocellulose hybrid fibers.
[0028] The ratio of mesoporous nano-silica, deionized water and modified nano-cellulose fibers is 0.1g:20mL:1-1.5g.
[0029] This invention also provides the application of a chitosan-based drug-loaded material in pesticide formulations, and the specific application method is as follows:
[0030] Step 1: Mix pesticide, glycerin and deionized water at a mass ratio of 10:1:100, stir at 600-1000 r / min for 10-15 min to obtain pesticide dispersion;
[0031] Step 2: Mix the chitosan-based drug-loaded material and deionized water at a mass ratio of 1:50, stir at 150-200 ml / min for 5-10 min, and redissolve the chitosan-based drug-loaded material to obtain the redissolved drug-loaded sol;
[0032] Step 3: Add the pesticide dispersion to the flask, and add an equal volume of the reconstituted pesticide-loaded sol to the flask while stirring at 300-500 r / min. After the addition is complete, continue stirring for 3-5 min, and degas under reduced pressure at room temperature and -0.08 MPa for 3-5 min to obtain the pesticide-loaded formulation.
[0033] Step 4: Store the pesticide-loaded sol and 0.3wt%-0.4wt% calcium chloride solution in the two storage compartments of the pesticide spraying equipment with dual nozzles, and then spray them onto the plant leaves simultaneously through the pesticide spraying equipment.
[0034] The beneficial effects of this invention are:
[0035] 1. The chitosan-based drug-loaded material of this invention is a freeze-dried product, which facilitates storage. This drug-loaded material uses mesoporous particles-nanocellulose hybrid fibers and short cellulose acetate nanofibers as a supporting framework, and is appropriately cross-linked through carboxymethyl chitosan, low-methoxyl pectin, and a suitable concentration of humic acid. This cross-linking does not affect reconstitution and application, but also improves the suspension stability of the drug-loaded material and pesticide formulation, reducing or avoiding particle sedimentation. When formulated into a drug-loaded pesticide formulation and sprayed simultaneously with calcium chloride solution, the low-methoxyl pectin responds rapidly to calcium ions, increasing the ionic cross-linking rate and helping carboxymethyl chitosan and other components quickly form a gel film and adhere to the leaves. This helps improve pesticide utilization, reduces or avoids re-spraying, and improves the production efficiency of short-harvest crops such as cucumbers.
[0036] 2. The chitosan-based drug-loaded material of this invention will not affect the normal growth of crops after loading pesticides and spraying. The short cellulose acetate nanofibers and mesoporous particles-nanocellulose hybrid fibers work together to provide spatial support and structural reinforcement. Within a certain growth period, the flexibility of the gel membrane reduces the degree of rupture caused by leaf growth and increased leaf area, thereby reducing the living space of harmful bacteria.
[0037] 3. Mesoporous particle-nanocellulose hybrid fibers, through grafting and bonding of mesoporous nano-silica-copper oxide composite particles and nanocellulose fibers, synergistically utilize hydrogen bonds and other forces to help the raw materials disperse evenly, thereby improving the suspension stability of pesticide formulations. The three-dimensional network composed of mesoporous particles and nanocellulose hybrid fibers can adsorb and fix pesticide particles. Nano-copper oxide has a contact killing effect and good biocompatibility, which helps to synergistically inhibit the growth and reproduction of harmful fungi such as *Peronospora cucumeroides*, improving the control effect of downy mildew.
[0038] 4. The low-methoxyl pectin and calcium ions in the chitosan-based drug-loaded material of this invention have better cross-linking effects, which helps to improve the gelation film formation rate, avoid solid sedimentation and droplet detachment, thereby increasing the stability of the drug-loaded pesticide formulation gel film. The growth and reproduction of *Peronospora cucumeroides* releases pectinase, and low-methoxyl pectin has a higher affinity for pectinase, which, after decomposition, facilitates the targeted release of pesticides. Detailed Implementation
[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0040] Example 1: A chitosan-based drug-loaded material, prepared by the following steps:
[0041] S1: 4g of nano-copper oxide, 100g of hexadecyltrimethylammonium bromide as a template agent, 3L of 25% ammonia solution, 3.5L of anhydrous ethanol, and 5L of deionized water were added to a reaction vessel. The mixture was stirred at 35℃ and 300r / min for 30min and then ultrasonically dispersed for 10min. 3.2mL of 1,2-bis(triethoxysilyl)ethane was then added to the reaction vessel, and stirring continued for 4h. The mixture was centrifuged at 8000r / min for 10min. The precipitate was washed sequentially with acid and 90%wt ethanol aqueous solution, and then vacuum dried at 60℃ to obtain mesoporous nano-silica-copper oxide composite particles. The acid solution was prepared by mixing 36wt% hydrochloric acid and anhydrous ethanol at a volume ratio of 1:500. The acid washing was performed three times, and the ethanol aqueous solution was used until the final wash solution was neutral.
[0042] S2: Propyltriethoxysilane isocyanate (IPTS) was prepared into a 0.5 mol / L IPTS solution using dimethyl sulfoxide; 240 mL of IPTS solution was transferred to a reaction vessel, and then 30 g of nanocellulose fibers and 3.3 g of dibutyltin dilaurate as a catalyst were added to the reaction vessel. The mixture was stirred at 60 °C and 200 r / min for 4 h, filtered, and the filter cake was washed twice with ethyl acetate and freeze-dried to obtain modified nanocellulose fibers.
[0043] S3: Add 2g of mesoporous nano-silica-copper oxide composite particles and 400mL of deionized water to the reactor and ultrasonically disperse for 10min. Then add 20g of modified nanocellulose fiber to the reactor and stir the reaction at 80℃ for 8h. After naturally cooling to room temperature, centrifuge and filter. Wash the filter cake twice with deionized water and freeze-dry to obtain mesoporous particle-nanocellulose hybrid fiber.
[0044] S4: Mix 6g of mesoporous particle-nanocellulose hybrid fiber and 1.5g of cellulose acetate short nanofibers and ultrasonically disperse them in 50 times their mass of deionized water for 10min. Then transfer the mixture to a stirred tank. Dissolve 1g of carboxymethyl chitosan and 1g of low-methoxyl pectin in 100 times their mass of deionized water and add them to the stirred tank. Stir at 40℃ and 300r / min for 30min. Then dissolve 0.1g of humic acid in 100 times their mass of deionized water and add it to the stirred tank. Make up the mass of the mixture with deionized water to 1000g and continue stirring for 20min. Centrifuge the obtained chitosan-based hydrosol at 8000r / min for 10min, remove the supernatant, and freeze-dry the remaining colloid to obtain the chitosan-based drug-loaded material.
[0045] Example 2: A chitosan-based drug-loaded material, prepared by the following steps:
[0046] S1: 4.5 g of nano-copper oxide, 110 g of hexadecyltrimethylammonium bromide as a template agent, 3.2 L of 25% ammonia solution, 3.8 L of anhydrous ethanol, and 5.5 L of deionized water were added to a reaction vessel. The mixture was stirred at 38 °C and 400 rpm for 35 min and ultrasonically dispersed for 12 min. Then, 3.5 mL of 1,2-bis(triethoxysilyl)ethane was added to the reaction vessel, and stirring was continued for 4.5 h. The mixture was centrifuged at 8000 rpm for 12 min. The precipitate was washed successively with acid and 90% wt% ethanol aqueous solution, and dried under vacuum at 70 °C to obtain mesoporous nano-silica-copper oxide composite particles. The acid solution was prepared by mixing 36 wt% hydrochloric acid and anhydrous ethanol at a volume ratio of 1:500. The acid washing was performed 4 times, and the ethanol aqueous solution was used for washing until the final washing solution was neutral.
[0047] S2: Propyltriethoxysilane isocyanate (IPTS) was prepared into a 0.5 mol / L IPTS solution using dimethyl sulfoxide; 270 mL of IPTS solution was transferred to a reaction vessel, and then 30 g of nanocellulose fibers and 3.6 g of dibutyltin dilaurate as a catalyst were added to the reaction vessel. The mixture was stirred at 65 °C and 250 r / min for 4.2 h, filtered, and the filter cake was washed twice with ethyl acetate and freeze-dried to obtain modified nanocellulose fibers.
[0048] S3: Add 2g of mesoporous nano-silica-copper oxide composite particles and 400mL of deionized water to the reactor and ultrasonically disperse for 15min. Then add 25g of modified nanocellulose fiber to the reactor and stir the reaction at 82℃ for 9h. After naturally cooling to room temperature, centrifuge and filter. Wash the filter cake twice with deionized water and freeze-dry to obtain mesoporous particle-nanocellulose hybrid fiber.
[0049] S4: Mix 7g of mesoporous particle-nanocellulose hybrid fiber and 1.8g of cellulose acetate short nanofibers and ultrasonically disperse them in 50 times their mass of deionized water for 15min. Then transfer the mixture to a stirred tank. Dissolve 1.1g of carboxymethyl chitosan and 1.1g of low-methoxyl pectin in 100 times their mass of deionized water and add them to the stirred tank. Stir at 45℃ and 400r / min for 45min. Dissolve 0.12g of humic acid in 100 times their mass of deionized water and add it to the stirred tank. Make up the mass of the mixture with deionized water to 1000g and continue stirring for 25min. Centrifuge the obtained chitosan-based hydrosol at 8000r / min for 12min, remove the supernatant, and freeze-dry the remaining colloid to obtain the chitosan-based drug-loaded material.
[0050] Example 3: A chitosan-based drug-loaded material, prepared by the following steps:
[0051] S1: 5g of nano-copper oxide, 120g of hexadecyltrimethylammonium bromide as a template agent, 3.5L of 25% ammonia solution, 4L of anhydrous ethanol, and 6L of deionized water were added to a reaction vessel. The mixture was stirred at 40℃ and 500r / min for 40min and ultrasonically dispersed for 15min. Then, 4mL of 1,2-bis(triethoxysilyl)ethane was added to the reaction vessel and stirring was continued for 5h. The mixture was centrifuged at 8000r / min for 15min. The precipitate was washed successively with acid solution and 90%wt ethanol aqueous solution, and dried under vacuum at 80℃ to obtain mesoporous nano-silica-copper oxide composite particles. The acid solution was prepared by mixing 36wt% hydrochloric acid and anhydrous ethanol at a volume ratio of 1:500. The acid washing was performed 5 times, and the ethanol aqueous solution was used for washing until the final washing solution was neutral.
[0052] S2: Propyltriethoxysilane isocyanate (IPTS) was prepared into a 0.5 mol / L IPTS solution using dimethyl sulfoxide; 300 mL of IPTS solution was transferred to a reaction vessel, and then 30 g of nanocellulose fibers and 3.9 g of dibutyltin dilaurate as a catalyst were added to the reaction vessel. The mixture was stirred at 70 °C and 300 r / min for 4.5 h, filtered, and the filter cake was washed three times with ethyl acetate and freeze-dried to obtain modified nanocellulose fibers.
[0053] S3: Add 2g of mesoporous nano-silica-copper oxide composite particles and 400mL of deionized water to the reactor and ultrasonically disperse for 20min. Then add 30g of modified nanocellulose fibers to the reactor and stir the reaction at 85℃ for 10h. After naturally cooling to room temperature, centrifuge and filter. Wash the filter cake three times with deionized water and freeze-dry to obtain mesoporous particle-nanocellulose hybrid fibers.
[0054] S4: Mix 8g of mesoporous particle-nanocellulose hybrid fiber and 2g of cellulose acetate short nanofibers and ultrasonically disperse them in 50 times their mass of deionized water for 10-20 min. Then transfer the mixture to a stirred tank. Dissolve 1.2g of carboxymethyl chitosan and 1.2g of low-methoxyl pectin in 100 times their mass of deionized water and add them to the stirred tank. Stir at 50℃ and 500r / min for 60 min. Dissolve 0.15g of humic acid in 100 times their mass of deionized water and add it to the stirred tank. Make up the mass of the mixture with deionized water to 1000g and continue stirring for 30 min. Centrifuge the obtained chitosan-based hydrosol at 8000r / min for 15 min, remove the supernatant, and freeze-dry the remaining colloid to obtain the chitosan-based drug-loaded material.
[0055] A method for applying chitosan-based drug-loaded materials is provided:
[0056] Step 1: Mix chlorothalonil powder (i.e., pesticide, particle size ≤2μm), glycerin and deionized water at a mass ratio of 10:1:100, and stir at 600r / min (600-1000r / min optional) for 10min (10-15min optional) to obtain pesticide dispersion; glycerin is used as a humectant.
[0057] Step 2: Mix the chitosan-based drug-loaded material and deionized water at a mass ratio of 1:50, stir at 150 r / min (150-200 r / min optional) for 5 min (5-10 min optional), and redissolve the chitosan-based drug-loaded material to obtain the redissolved drug-loaded sol.
[0058] Step 3: Add 50 mL of pesticide dispersion to the flask, and add 50 mL of reconstituted pesticide-loaded sol to the flask under stirring conditions of 300 r / min (300-500 r / min optional). After the addition is complete, continue stirring for 3-5 min, and degas under reduced pressure at room temperature and -0.08 MPa for 3 min (3-5 min optional) to obtain the pesticide-loaded formulation.
[0059] Step 4: Store pesticide-loaded sol and calcium chloride solution with a mass concentration of 0.3wt% (0.3wt%-0.4wt% optional) in the two storage compartments of the pesticide spraying equipment with dual nozzles, and spray the pesticide onto the cucumber leaves using the pesticide spraying equipment.
[0060] Comparative Example 1: The difference from Example 3 is that cellulose acetate short nanofibers are not added in step S4, while the other steps remain unchanged, and a drug-loaded material is prepared.
[0061] Comparative Example 2: The difference from Example 3 is that mesoporous particles-nanocellulose hybrid fibers are not added in step S4, while the other steps remain unchanged, and a drug-loaded material is prepared.
[0062] Comparative Example 3: The difference from Example 3 is that in step S1, no nano-copper oxide is added, and mesoporous nano-silica is prepared to replace the mesoporous nano-silica-copper oxide composite particles in step S3. The remaining steps remain unchanged to prepare the drug-loaded material.
[0063] Comparative Example 4: The difference from Example 3 is that, without step S3, 2g of mesoporous nano-silica-copper oxide composite particles and 30g of nano-cellulose fibers were directly mixed as mesoporous particle-nano-cellulose hybrid fibers in step S4, while the other steps remained unchanged, to prepare the drug-loaded material.
[0064] Comparative Example 5: The difference from Example 3 is that in step S4, low-methoxyl pectin is replaced with high-methoxyl pectin, while the other steps remain unchanged, and a drug-loaded material is prepared.
[0065] Comparative Example 6: The difference from Example 3 is that in step S4, the amount of humic acid was increased to 1.5g, while the other steps remained unchanged, and the drug-loaded material was prepared.
[0066] Comparative Example 7: The difference from Example 3 is that humic acid will not be added in step S4, while the remaining steps remain unchanged, and a drug-loaded material is prepared.
[0067] In the examples and comparative examples, the nano-copper oxide was designated YM-CuO, branded by Yumu Nano, with catalog number YM-CuO-N80 and an average particle size of 80 nm; the 1,2-bis(triethoxysilyl)ethane was designated CT11929, and the propyltriethoxysilane was designated CAS number 24801-88-5, branded by Xinyuhong; the nano-cellulose fiber was designated TL003, branded by Tianlu Nano, with a diameter of 4-10 nm and a length of 100-500 nm. The surface functional groups contain hydroxyl and carboxyl groups; the average diameter of the short cellulose acetate nanofibers is 700 nm and the average length is 1.8 μm; the CAS number of carboxymethyl chitosan is 83512-85-0, and the brand is Kemic; the CAS number of low-methoxyl pectin is 9000-69-5, and the brand is Luofu Biotechnology; the model of high-methoxyl pectin is XH5280VDY7V2, and the brand is Shenghe Chemical; the purity of humic acid is 98%, the CAS number is 1415-93-6, and the brand is Xiya Reagent.
[0068] The short nanofibers of cellulose acetate were obtained by electrospinning of cellulose acetate (Mn=30000, CAS: 9004-35-7, brand: Shanghai Aladdin). The specific method of electrospinning was as follows: cellulose acetate was dissolved in an organic solvent (dimethyl sulfoxide: acetone = 2:3 (v / v)) to prepare a spinning solution with a concentration of 18wt%. The solution was spun using an electrospinning machine (model PS-2+, brand Pansi Technology) at a humidity of 35% and a temperature of 25℃. The voltage of the electrospinning was 20kV, the flow rate of the spinning solution was 1mL / h, and the distance between the No. 21 flat needle and the collector was 15cm. The fiber membrane collected by the collector was crushed, dispersed and homogenized with deionized water. The homogenizer (model T25, brand IKA) was used at a speed of 12000r / min for 30min. The homogenized product was freeze-dried to obtain the short nanofibers of cellulose acetate.
[0069] Performance tests were conducted on the drug-loaded materials used in the examples and comparative examples:
[0070] The fungal spores of *Pseudomonas cucumeris* were cultured on PDA medium at 28°C for 3 days. Pathogen blocks with a diameter of 5 mm were then collected for later use.
[0071] PDA medium composition: potato, derived from its extract: 200 g / L; glucose: 20 g / L; agar: 15.0 g / L; pH (25℃) 5.6.
[0072] Different drug-loaded materials are formulated into drug-loaded pesticide formulations according to the application method of this application, for later use.
[0073] The pesticide dispersion was diluted with deionized water by one-tenth and used as the original pesticide control group; another deionized water was used as the blank control group.
[0074] Cucumbers (variety: Yuanfengyuan No. 6) were cultivated in pots in a greenhouse. Two-leaf stage cucumber seedlings with similar growth conditions were selected as experimental plants, totaling 12 groups with 100 plants in each group. Following the method in step 4 of the application, the pesticide formulations and samples from the control group and blank control group in the examples and comparative examples were sprayed on both sides of the cucumber leaves in each group, ensuring uniform and consistent spraying.
[0075] The treated cucumber seedlings were transferred to an artificial greenhouse and placed in 10 rows and 10 columns for cultivation (temperature: 25℃ during the day and 20℃ at night; relative humidity: 85%) for 24 hours. The pathogenic fungal blocks were then inoculated onto the cucumber seedling leaves, and cultivation continued for 7 days. The presence of disease characteristics such as necrotic spots and mycelium on the leaves was observed, and the percentage of diseased plants in each group was recorded as the incidence rate. Then, five pots of plants were selected using a double diagonal fixed 5-point sampling method, and the average diameter of the necrotic spots was measured and calculated. The results are shown in Table 1.
[0076] Table 1. Results of the control effect of pesticide formulations on cucumber downy mildew.
[0077]
[0078] As shown in Table 1, compared with the original drug control group and the blank control group, the pesticide formulations in the examples exhibited good control effects against cucumber downy mildew and had minimal impact on the normal growth of cucumber seedlings. The presence of diseased plants in Comparative Example 2 may be due to uneven spraying, leading to pathogen infection.
[0079] Comparative Example 1, without the addition of cellulose acetate short nanofibers, showed a decreased control effect. This may be due to the lack of structural reinforcement and spatial support provided by the cellulose acetate short nanofibers, resulting in decreased gel membrane stability. In addition, the increased leaf area due to leaf growth led to gel decomposition and collapse, increasing the number of cracks and facilitating the infection of *Pseudomonas cucumeroides*.
[0080] In Comparative Example 2, the lack of addition of mesoporous particle-nanocellulose hybrid fibers significantly reduced the control effect. This was due to two factors: firstly, the lack of these fibers to load the active ingredient, leading to uneven dispersion; and secondly, the lack of their ability to enhance the stability and strength of the gel membrane structure. Comparative Example 3 also shows that the doping of nano-copper oxide can improve the control effect because nano-copper oxide has good contact killing effects and can synergistically inhibit the growth and reproduction of *Peronospora cucumeroides*.
[0081] The decreased prevention and control effect in Comparative Example 4 may be due to the lack of graft bonding between the mesoporous nano-silica-copper oxide composite particles and nano-cellulose fibers. Due to the large quality difference between the mesoporous nano-silica-copper oxide composite particles and other raw materials, sedimentation occurred, leading to a decrease in the stability of the gel membrane.
[0082] The decreased control efficacy in Comparative Example 5 is attributed to the better cross-linking effect of low-methoxyl pectin and calcium ions, which helps to increase the gel film formation rate, avoid solid sedimentation and droplet detachment, thereby increasing the stability of the pesticide-loaded gel film. Furthermore, studies have shown that the growth and reproduction of *Peronospora cucumeroides* releases pectinase, and low-methoxyl pectin has a higher affinity for pectinase, which, after decomposition, facilitates the targeted release of pesticides.
[0083] Comparative Examples 6 and 7 show that both excessively high and low humic acid concentrations can affect the control efficacy against downy mildew. Excessive humic acid concentration can lead to over-crosslinking of the pesticide-loaded material in the early stages, potentially affecting subsequent gelation with calcium ions. Without humic acid, there is no pre-crosslinking, which may reduce the stability of the pesticide-loaded material after reconstitution, causing the pesticide formulation to settle in the storage silo.
[0084] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.
[0085] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.
Claims
1. A chitosan-based drug-loaded material, characterized in that, Chitosan-based hydrosol was prepared by centrifugation and freeze-drying. The chitosan-based hydrosol comprises the following raw materials in the indicated mass percentages: Mesoporous particles-nanocellulose hybrid fibers 0.6%-0.8%, cellulose acetate short nanofibers 0.15%-0.2%, carboxymethyl chitosan 0.1%-0.12%, low-methoxyl pectin 0.1%-0.12%, humic acid 0.01%-0.015%, balance being deionized water; The preparation method of the mesoporous particle-nanocellulose hybrid fiber is as follows: Using dibutyltin dilaurate as a catalyst, propyltriethoxysilane isocyanate was grafted onto the surface of nanocellulose fibers via carbamylation to obtain modified nanocellulose fibers. The grafted siloxane was then hydrolyzed and bonded to the hydroxyl groups of mesoporous nanosilica-copper oxide composite particles to prepare mesoporous particle-nanocellulose hybrid fibers.
2. The chitosan-based drug-loaded material according to claim 1, characterized in that, The specific preparation method of chitosan-based drug-loaded materials is as follows: Mesoporous particles-cellulose nanofiber hybrids and cellulose acetate short nanofibers were mixed and ultrasonically dispersed in 50 times their mass of deionized water for 10-20 min. The mixture was then added to a stirred tank. Carboxymethyl chitosan and low-methoxyl pectin were dissolved in 100 times their mass of deionized water and added to the stirred tank. The mixture was stirred at 40-50℃ and 300-500 r / min for 30-60 min. Humic acid was then dissolved in 100 times its mass of deionized water and added to the stirred tank. Deionized water was added as needed, and the mixture was stirred for another 20-30 min to obtain a chitosan-based hydrosol.
3. The chitosan-based drug-loaded material according to claim 1, characterized in that, The mesoporous nano-silica-copper oxide composite particles are prepared by the following steps: Nano-copper oxide, hexadecyltrimethylammonium bromide, 25wt% ammonia, anhydrous ethanol, and deionized water were added to a reaction vessel and stirred at 35-40℃ and 300-500 rpm for 30-40 min, followed by ultrasonic dispersion for 10-15 min. Then, 1,2-bis(triethoxysilyl)ethane was added to the reaction vessel and stirring was continued for 4-5 h. The mixture was centrifuged at 8000 rpm for 10-15 min. The precipitate was washed sequentially with acid and 90%wt ethanol aqueous solution, and then vacuum dried at 60-80℃ to obtain mesoporous nano-silica-copper oxide composite particles.
4. The chitosan-based drug-loaded material according to claim 3, characterized in that, The acid washing is performed 3-5 times, and the ethanol-water solution washing is performed until the final washing solution is neutral. The acid solution is obtained by mixing 36wt% hydrochloric acid and anhydrous ethanol at a volume ratio of 1:
500.
5. The chitosan-based drug-loaded material according to claim 3, characterized in that, The ratio of the amounts of nano-copper oxide, hexadecyltrimethylammonium bromide, ammonia, anhydrous ethanol, deionized water, and 1,2-bis(triethoxysilyl)ethane is 40-50 mg: 1-1.2 g: 30-35 mL: 35-40 mL: 50-60 mL: 32-40 μL.
6. The chitosan-based drug-loaded material according to claim 1, characterized in that, The modified nanocellulose fibers are prepared through the following steps: The IPTS solution was transferred to a reaction vessel, and nanocellulose fibers and dibutyltin dilaurate were added. The mixture was stirred at 60-70℃ and 200-300r / min for 4-4.5h. The mixture was then filtered, and the filter cake was washed 2-3 times with ethyl acetate and freeze-dried to obtain modified nanocellulose fibers. The IPTS solution was prepared by dissolving propyltriethoxysilane isocyanate (IPTS) in dimethyl sulfoxide.
7. The chitosan-based drug-loaded material according to claim 6, characterized in that, The ratio of the IPTS solution, nanocellulose fiber, and dibutyltin dilaurate is 8-10 mL: 1 g: 0.11-0.13 g.
8. The chitosan-based drug-loaded material according to claim 1, characterized in that, The specific preparation steps of the mesoporous particle-nanocellulose hybrid fiber are as follows: Mesoporous nano-silica-copper oxide composite particles and deionized water were added to a reaction vessel and ultrasonically dispersed for 10-20 min. Then, modified nanocellulose fibers were added to the reaction vessel and stirred at 80-85℃ for 8-10 h. After naturally cooling to room temperature, the mixture was centrifuged and filtered. The filter cake was washed 2-3 times with deionized water and freeze-dried to obtain mesoporous particle-nanocellulose hybrid fibers.
9. A chitosan-based drug-loaded material according to claim 8, characterized in that, The ratio of mesoporous nano-silica, deionized water, and modified nano-cellulose fibers is 0.1g:20mL:1-1.5g.
10. The application of a chitosan-based drug-loaded material as described in any one of claims 1-9 in pesticide formulations, characterized in that, The specific application methods are as follows: Step 1: Mix pesticide, glycerin and deionized water at a mass ratio of 10:1:100, stir at 600-1000 r / min for 10-15 min to obtain pesticide dispersion; Step 2: Mix the chitosan-based drug-loaded material and deionized water at a mass ratio of 1:50, stir at 150-200 ml / min for 5-10 min, and redissolve the chitosan-based drug-loaded material to obtain the redissolved drug-loaded sol; Step 3: Add the pesticide dispersion to the flask, and add an equal volume of the reconstituted pesticide-loaded sol to the flask while stirring at 300-500 r / min. After the addition is complete, continue stirring for 3-5 min, and degas under reduced pressure at room temperature and -0.08 MPa for 3-5 min to obtain the pesticide-loaded formulation. Step 4: Store the pesticide-loaded sol and 0.3wt%-0.4wt% calcium chloride solution in the two storage compartments of the pesticide spraying equipment with dual nozzles, and then spray them onto the plant leaves simultaneously through the pesticide spraying equipment.