Preparation method of silicon-based multi-cavity microcapsule with weak acid response

Abstract

The invention aims to provide a preparation method of a weak acid response silicon-based multi-cavity microcapsule which realizes on-demand diagnosis and treatment of crop virus diseases, is assembled into a multi-cavity structure through a microfluidic technology and is gated by using a pH-sensitive silane coupling agent. The preparation method comprises the following steps: taking mesoporous silicon dioxide nanoparticles as a basic unit; a multi-cavity structure is assembled through a microfluidic technology, a pH-sensitive silane coupling agent is utilized for gating, an immune resistance inducer (chitosan oligosaccharide) loaded in a cavity A is preferentially released in an explosive mode after sensing weak acid, and system resistance is started; the probiotics packaged in the chamber B are colonized under acidic triggering to compete for ecological niche; the trace elements in the chamber C are continuously supplied through the slow-release silicon substrate, so that the slow-release silicon substrate has high sensitivity to the change of the pH value and can accurately activate the immune response at the TMV infection site, the prevention effect of the potted plant is improved to 89.5%, and the slow-release silicon substrate has extremely small influence on a non-target area.

Description

Technical Field

[0001] This invention relates to the field of agriculture. Specifically, it relates to a method for preparing weakly acid-responsive silicon-based multi-chamber microcapsules. Background Technology

[0002] Plant disease infection is often accompanied by a decrease in the pH of the phyllosphere microenvironment. This specific signal provides a natural target for precision plant protection. The importance and cutting-edge nature of the plant disease microenvironment (especially pH changes) as a target lies in the application of mesoporous silica nanomaterials (MSNs) in drug delivery, particularly their pH-responsive gating design (e.g., modified with crown ethers, phthalic acid, etc.). Utilizing the modifiability of silicon-based materials, a multi-chamber system capable of sensing disease and weak acid signals and executing programmed release can be constructed, achieving unprecedented precision immune activation. This involves the explicit use of mesoporous silica nanoparticles (MSNs) and specific pH-responsive silane coupling agents (such as silanes containing carboxyl or acylhydrazone bonds). Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is to provide a method for preparing a weakly acid-responsive silicon-based multi-chamber microcapsule that enables "on-demand diagnosis and treatment" of crop viral diseases by assembling it into a multi-chamber structure using microfluidic technology and using a pH-sensitive silane coupling agent for gating.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A method for preparing a weakly acid-responsive silicon-based multi-cavity microcapsule includes the following steps: The first step is to synthesize A-aldehyde silane as an organosilanes: In a glass reactor equipped with a stirrer, thermometer and reflux condenser, anhydrous ethanol is added as a solvent, followed by 3-propyltriethoxysilane and 4-hydroxybenzaldehyde in a molar ratio of 1:1, and then dibutyltin dilaurate is added as a catalyst. The reaction is stirred at 60°C for 6-8 hours. After the reaction is completed, the solvent is removed by rotary evaporator to obtain the aldehyde-modified silane intermediate. The second step involves forming a β-hydrazone bond. The prepared aldehyde-modified silane intermediate is dissolved in methanol, and hexamethylenediamine is added dropwise as a compound containing an amino group to participate in the reaction. The reaction is stirred at room temperature for 4–6 hours. The aldehyde group reacts with the amino group to form a β-hydrazone bond -C=NN-. The methanol is then recovered by rotary evaporation to obtain the β-hydrazone-bridged organosilane precursor. The third step involves preparing nanoscale targeted silicon spheres. First, an oil phase is prepared: in a shear emulsification vessel, a complex of cyclohexane, Span 80, and Tween 80 in the oil phase is added as a surfactant. Reconfigure the aqueous phase: In another container, use ammonia as deionized water to dissolve the catalyst and amino acids as water-soluble active substances that need to be coated; Emulsification: The aqueous phase is added dropwise to the oil phase under shear at 10,000 rpm and sheared continuously for 20-30 minutes to form a transparent or translucent, thermodynamically stable oil-in-water microemulsion. The fourth step involves the formation of an interfacial hydrolysis-condensation and shell layer. The hydrazone-bridged organosilane precursor formed in the second step is added dropwise to the microemulsion obtained in the third step. The system is maintained at 30-40°C and continuously stirred for 12-24 hours, allowing the precursor to diffuse to the oil-water interface of the water core, where hydrolysis and condensation reactions occur, forming a cross-linked silica sphere shell. This shell encapsulates the active material in the water core as chamber 1, thus obtaining a microemulsion containing supported targeted silica spheres. The fifth step is demulsification and washing. Excess acetone is added to the microemulsion after the reaction to disrupt the emulsion equilibrium and cause the nanosilicon spheres to precipitate. The precipitate nanosilicon spheres are then collected by centrifugation and washed and centrifuged multiple times with a mixture of ethanol and acetone to remove surfactants and unreacted impurities. The washed nanosilicon sphere wet cake is then redispersed in deionized water or a pH-neutral buffer to form an aqueous suspension, thereby obtaining targeted silicon spheres containing active ingredients. Step 6, secondary loading and compounding, liposome preparation: Brassinolide, as an oil-soluble active ingredient, is co-dissolved with phospholipids in warm water and processed by a high-pressure homogenizer to form nanoliposomes. Then, the targeted silica sphere suspension and the nanoliposome liquid are mixed in a stirred tank. By adjusting the pH and ionic strength, the positively charged liposomes are adsorbed onto the negatively charged silica sphere surface to form chamber 2. Potassium metasilicate as water-soluble silica, surfactant, glycerol as antifreeze, and xanthan gum as thickening and stabilizing agent are added to the mixture. After stirring evenly, the mixture is circulated at 50-80 MPa using a high-pressure homogenizer until it is uniformly mixed.

[0005] Step 7: Maturation and filtration. After homogenization, the mixture is allowed to stand at room temperature for 24-48 hours to stabilize its physicochemical properties. Then, it is filtered through a bag filter with a pore size of 1-5 μm to produce weakly acid-responsive silicon-based multi-chamber microcapsules.

[0006] The technical solution of the present invention achieves the following beneficial technical effects: 1. In summary, this system was successfully constructed as a "precision immunization delivery system driven by the disease microenvironment". By changing the gating mechanism (such as oxidation response and enzyme response), this silicon-based multi-cavity platform can be applied to a wider range of disease prevention and control. 2. By combining with drones and sensors, we can achieve "targeted delivery" based on disease prediction, truly moving towards smart agriculture; 3. By comparing the expression levels of immune genes in the local area of ​​virus infection sites and healthy tissues with those of ordinary milk preparations and non-targeted microcapsules, the precise activation ability of this system is demonstrated.

[0007] 4. It requires less dosage, has better effects, and lower environmental emissions, fully meeting the requirements of green agriculture. Attached Figure Description

[0008] none Detailed Implementation

[0009] This embodiment is applicable to soils with a wide pH range. Through targeted release, it improves soil aggregate structure, promotes crop absorption, enhances stress resistance, and improves quality.

[0010] Phase 1: The synthesis of weakly acid-sensitive silicon-based precursors serves as the chemical basis for achieving targeted functions.

[0011] First, the organosilane precursor is prepared.

[0012] Objective: To synthesize an organosilane compound whose chemical bonds break under weakly acidic conditions. This will serve as a raw material for constructing targeted silicon spherical shells.

[0013] Taking the synthesis of "hydrazone-bridged silanes" as an example: The first step is the synthesis of A-aldehyde silanes: Anhydrous ethanol is added as a solvent to a glass reactor equipped with a stirrer, thermometer, and reflux condenser.

[0014] Add 3-propyltriethoxysilane and 4-hydroxybenzaldehyde in a molar ratio of 1:1.

[0015] Dibutyltin dilaurate was added as a catalyst, and the reaction was stirred at 60°C for 6-8 hours.

[0016] After the reaction was complete, the solvent was removed by rotary evaporation to obtain the aldehyde-modified silane intermediate.

[0017] The second step is the formation of the β-hydrazone bond: The above-mentioned aldehyde silane intermediate was dissolved in methanol.

[0018] Hexamethylenediamine, a compound containing an amino group, is added dropwise slowly. It is essential to ensure that one amino group is protected or used in excess. The reaction is stirred at room temperature for 4–6 hours. The aldehyde group reacts with the amino group to form a hydrazone bond -C=NN-.

[0019] Methanol was recovered by rotary evaporation to obtain the final product—a hydrazone-bridged organosilanes precursor.

[0020] The precursor contains hydrolyzable siloxane groups and acid-sensitive hydrazone bonds.

[0021] Main equipment: glass reaction vessel with temperature control and stirring, rotary evaporator, vacuum drying oven, analytical balance.

[0022] Main materials: 3-propyltriethoxysilane isocyanate, 4-hydroxybenzaldehyde, dibutyltin dilaurate, anhydrous ethanol, methanol, hexamethylenediamine.

[0023] Phase 2: Construction of a "multi-cavity" structure - Preparation of nanoscale targeted silicon spheres using microemulsion polymerization technology.

[0024] Step 1: Preparation of W / O type microemulsion Objective: To create tiny “water cores” as nanoreactors in which subsequent silicon sphere synthesis will take place.

[0025] 1. Oil phase preparation: In a high-speed shear emulsification vessel, a mixture of cyclohexane, Span 80 and Tween 80 in the oil phase is added as a surfactant.

[0026] 2. Aqueous phase preparation: In another container, deammoniated water is used as the catalyst for dissolving ionized water, along with amino acids, potassium humate, trace elements, etc., as water-soluble active substances that need to be encapsulated. This will be the contents of the future "chamber 1".

[0027] 3. Emulsification: Under high-speed shearing at 10,000 rpm, the aqueous phase is slowly added dropwise to the oil phase. Shearing continues for 20–30 minutes, forming a transparent or translucent, thermodynamically stable oil-in-water microemulsion. At this point, the system contains hundreds of millions of tiny water nuclei.

[0028] Main equipment: high-speed shear emulsifier, batching tank, constant temperature water bath.

[0029] Main materials: cyclohexane, Span 80, Tween 80, ammonia, deionized water, amino acids, potassium humate, etc.

[0030] Step 2: Interfacial hydrolysis and condensation, and shell formation: Objective: To hydrolyze and condense silane precursors at the water-core interface of microemulsions to form a silica shell with hydrazone bonds that encapsulates the water core.

[0031] 1. Silane addition: Under slow stirring, the hydrazone-bridged organosilane precursor synthesized in the first stage is added dropwise to the microemulsion.

[0032] 2. Reaction: Maintain the system at 30-40℃ and continuously stir for 12-24 hours. The precursor will diffuse to the oil-water interface of the water core, undergo hydrolysis and condensation reactions, and form a cross-linked silicon spherical shell layer, which encapsulates the active material in the water core as chamber 1.

[0033] 3. Reaction complete: A microemulsion containing supported targeted silica spheres is obtained.

[0034] Main equipment: glass reactor with stirring and temperature control.

[0035] Main materials: hydrazone-bridged organosilicon precursor, W / O microemulsion.

[0036] Phase Three: Post-processing and Functional Modification Technology IV: Demulsification and Cleaning Objective: To separate synthesized silicon nanospheres from the microemulsion system.

[0037] 1. Demulsification: Add excess acetone or ethanol to the microemulsion after the reaction to disrupt the emulsion equilibrium and cause the nano-silicon spheres to precipitate.

[0038] 2. Centrifugal separation: Centrifuge using a high-speed centrifuge to collect the precipitate, i.e., nano-silicon spheres.

[0039] 3. Washing: Wash and centrifuge repeatedly with a mixture of ethanol and acetone to remove surfactants and unreacted impurities.

[0040] 4. Dispersion: The washed nano-silicon sphere wet cake is redispersed in deionized water or pH neutral buffer to form an aqueous suspension. Thus, the core functional unit, the targeted silicon sphere containing active ingredients, is obtained.

[0041] Main equipment: high-speed centrifuge, ultrasonic disperser, and vacuum filtration device.

[0042] Main materials: acetone, ethanol, deionized water.

[0043] Secondary loading and compounding are used to construct a "multi-cavity" function.

[0044] Objective: To combine other incompatible active ingredients, such as fat-soluble vitamins and essential oils, with targeted silicon spheres through physical adsorption or encapsulation to achieve a "multi-cavity" function.

[0045] 1. Preparation of liposomes / microemulsions: Oil-soluble active ingredients, such as brassinolide and vitamin E, are co-dissolved with phospholipids in warm water and then processed by a high-pressure homogenizer to form nanoliposomes.

[0046] 2. Physical mixing: The targeted silica sphere suspension and nanoliposome liquid are gently mixed in a stirred tank. By adjusting the pH and ionic strength, the positively charged liposomes are adsorbed onto the negatively charged silica sphere surface, or vice versa, thereby forming "chamber 2".

[0047] 3. Adding additives: Add water-soluble silicon (such as potassium metasilicate), surfactant, antifreeze agent (such as glycerol), and thickening and stabilizing agent (such as xanthan gum) to the mixture and stir well.

[0048] 4. Homogenization: The product is cyclically processed several times under medium pressure of 50-80 MPa using a high-pressure homogenizer to ensure that the product is uniform, stable, and not prone to stratification and sedimentation.

[0049] Main equipment: mixing tank, high-pressure homogenizer.

[0050] Main materials: Targeted silica ball suspension, phospholipids, oil-soluble active ingredients, potassium metasilicate, surfactants, glycerol, xanthan gum.

[0051] Phase 4: Finished Product Production and Quality Control.

[0052] Curing, filtration and filling Objective: To obtain the final product.

[0053] 1. Maturation: Allow the homogenized product to stand at room temperature for 24-48 hours to stabilize its physicochemical properties.

[0054] 2. Filtration: A bag filter with a pore size of 1-5μm is used to remove any small amount of large particles that may be present, ensuring product permeability.

[0055] 3. Quality Inspection: Testing pH value, viscosity, specific gravity, dilution stability, silicon content, active ingredient content, etc.

[0056] 4. Filling: Packaging is carried out using an automatic liquid filling machine.

[0057] Main equipment: storage tanks, bag filtration system, liquid filling machine, laboratory testing equipment.

[0058] Main materials: finished liquid, packaging bottles / barrels.

[0059] Summary and process flow diagram Overall process route: Organic synthesis → Weak acid-sensitive silane precursor → Microemulsion preparation (creating water core) → Interfacial polymerization (forming targeted silica spheres) → Demulsification and cleaning → Secondary compounding (constructing multi-cavity) → Homogenization and stabilization → Filtration and filling → Finished product.

[0060] Mechanism of action: 1. Wide pH adaptability: The product is a liquid and can be applied evenly in both acidic and alkaline soils. The common water-soluble silica, such as potassium metasilicate, provides immediate relief.

[0061] 2. Targeted and Long-Lasting Effect: The core nano-targeted silica spheres are stable in neutral / alkaline soils. When crop roots secrete organic acids, creating a weakly acidic rhizosphere environment, the hydrazone bonds in the silica sphere shell break, causing the shell to disintegrate.

[0062] 3. Synergistic effects: Chamber 1 is located inside the silicon sphere: it releases amino acids, humic acid, etc., to stimulate root growth and improve the rhizosphere microecology.

[0063] Chamber 2 is located on the surface / outside of the silicon sphere: oil-soluble active substances embedded in liposomes are released, regulating endogenous hormones in crops and enhancing stress resistance.

[0064] Silicon itself: deposited in crop cell walls, enhancing physical resistance; and at the same time improving soil structure.

[0065] 4. Improve quality: Through systematic regulation, it promotes the balanced absorption of nutrients and the synthesis of secondary metabolites by crops, thereby significantly improving the sugar content, vitamin C content and appearance of fruits and vegetables, and meeting the standards of organic farming.

[0066] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A method for preparing a weakly acid-responsive silicon-based multi-cavity microcapsule, characterized in that, Includes the following steps: The first step is to synthesize A-aldehyde silane as an organosilanes: In a glass reactor equipped with a stirrer, thermometer and reflux condenser, anhydrous ethanol is added as a solvent, followed by 3-propyltriethoxysilane and 4-hydroxybenzaldehyde in a molar ratio of 1:1, and then dibutyltin dilaurate is added as a catalyst. The reaction is stirred at 60°C for 6-8 hours. After the reaction is completed, the solvent is removed by rotary evaporator to obtain the aldehyde-modified silane intermediate. The second step involves forming a β-hydrazone bond. The prepared aldehyde-modified silane intermediate is dissolved in methanol, and hexamethylenediamine is added dropwise as a compound containing an amino group to participate in the reaction. The reaction is stirred at room temperature for 4–6 hours. The aldehyde group reacts with the amino group to form a β-hydrazone bond -C=NN-. The methanol is then recovered by rotary evaporation to obtain the β-hydrazone-bridged organosilane precursor. The third step involves preparing nanoscale targeted silicon spheres. First, an oil phase is prepared: in a shear emulsification vessel, a complex of cyclohexane, Span 80, and Tween 80 in the oil phase is added as a surfactant. Reconfigure the aqueous phase: In another container, use ammonia as deionized water to dissolve the catalyst and amino acids as water-soluble active substances that need to be coated; Emulsification: The aqueous phase is added dropwise to the oil phase under shear at 10,000 rpm and sheared continuously for 20-30 minutes to form a transparent or translucent, thermodynamically stable oil-in-water microemulsion. The fourth step involves the formation of an interfacial hydrolysis-condensation and shell layer. The hydrazone-bridged organosilane precursor formed in the second step is added dropwise to the microemulsion obtained in the third step. The system is maintained at 30-40°C and continuously stirred for 12-24 hours, allowing the precursor to diffuse to the oil-water interface of the water core, where hydrolysis and condensation reactions occur, forming a cross-linked silica sphere shell. This shell encapsulates the active material in the water core as chamber 1, thus obtaining a microemulsion containing supported targeted silica spheres. The fifth step is demulsification and washing. Excess acetone is added to the microemulsion after the reaction to disrupt the emulsion equilibrium and cause the nanosilicon spheres to precipitate. The precipitate nanosilicon spheres are then collected by centrifugation and washed and centrifuged multiple times with a mixture of ethanol and acetone to remove surfactants and unreacted impurities. The washed nanosilicon sphere wet cake is then redispersed in deionized water or a pH-neutral buffer to form an aqueous suspension, thereby obtaining targeted silicon spheres containing active ingredients. Step 6, secondary loading and compounding, liposome preparation: Brassinolide, as an oil-soluble active ingredient, is co-dissolved with phospholipids in warm water and processed by a high-pressure homogenizer to form nanoliposomes. Then, the targeted silica sphere suspension and the nanoliposome liquid are mixed in a stirred tank. By adjusting the pH and ionic strength, the positively charged liposomes are adsorbed onto the negatively charged silica sphere surface to form chamber 2. Potassium metasilicate as water-soluble silicon, surfactant, glycerol as antifreeze, and xanthan gum as thickening and stabilizing agent are added to the mixture. After stirring evenly, the mixture is circulated at 50-80 MPa using a high-pressure homogenizer until it is evenly mixed. Step 7: Maturation and filtration. After homogenization, the mixture is allowed to stand at room temperature for 24-48 hours to stabilize its physicochemical properties. Then, it is filtered through a bag filter with a pore size of 1-5 μm to produce weakly acid-responsive silicon-based multi-chamber microcapsules.

2. The method for preparing weakly acid-responsive silicon-based multi-cavity microcapsules according to claim 1, characterized in that, In the second step, the amino compound added must ensure that one of the amino groups is protected or used in excess.

3. The method for preparing weakly acid-responsive silicon-based multi-cavity microcapsules according to claim 2, characterized in that, The organosilane precursor contains a hydrolyzable siloxane group and an acid-sensitive hydrazone bond.

4. The method for preparing weakly acid-responsive silicon-based multi-cavity microcapsules according to claim 1, characterized in that, The water-soluble active substances include amino acids, potassium humate, and trace elements.

5. The method for preparing weakly acid-responsive silicon-based multi-cavity microcapsules according to claim 1, characterized in that, The fourth step involves hydrolyzing and condensing the silane precursor at the water-core interface of the microemulsion, thereby encapsulating the water core with silica containing hydrazone bonds to form a shell.

6. The method for preparing weakly acid-responsive silicon-based multi-cavity microcapsules according to claim 1, characterized in that, The fifth step is used to separate the synthesized silicon nanospheres from the microemulsion system.

7. The method for preparing weakly acid-responsive silicon-based multi-cavity microcapsules according to claim 6, characterized in that, The additive in the demulsification reaction is acetone or ethanol, which disrupts the emulsion balance to cause the nano-silicon spheres to precipitate.

8. The method for preparing weakly acid-responsive silicon-based multi-cavity microcapsules according to claim 1, characterized in that, The sixth step is used to combine incompatible fat-soluble vitamins or essential oil active ingredients with targeted silicon spheres through physical adsorption or encapsulation to achieve multi-cavity functionality.

9. The method for preparing weakly acid-responsive silicon-based multi-cavity microcapsules according to claim 1, characterized in that, It also includes quality inspection and filling, with tests performed on pH value, viscosity, specific gravity, dilution stability, silicon content, and active ingredient content.

10. The method for preparing weakly acid-responsive silicon-based multi-cavity microcapsules according to claim 1, characterized in that, The process flow is as follows:

1. Organic synthesis, 2. Weak acid sensitive silane precursor, 3. Microemulsion preparation, i.e., creating water cores, 4. Interfacial polymerization, i.e. forming targeted silicon spheres, 5. Demulsification and cleaning, 6. Secondary compounding, i.e. constructing multi-cavity, 7. Homogenization and stabilization, 8. Filtration and filling, 9. Finished product.