Nanometer hydrogel preparation for packaging small interfering RNA and preparation method of nanometer hydrogel preparation

Abstract

The invention discloses a nano hydrogel preparation for packaging small interfering RNA (Ribonucleic Acid) and a preparation method, and belongs to the technical field of nano pesticides. Gold nanoparticles and dendritic mesoporous silica nanoparticles are used as composite carriers to load small interfering RNA, then a pectin solution is used for packaging, and the nano hydrogel preparation is prepared, so that the adhesion of a medicament is greatly enhanced, and rapid permeation and targeted delivery of the medicament are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of nanopesticides, and in particular to a nano hydrogel preparation for encapsulating small interfering RNA and a preparation method thereof. Background Art

[0002] Gene interference technology (RNAi) is the complementary binding of small interfering RNA (siRNA) or miRNA to the mRNA of the target gene to form an RNA-induced silencing complex, which causes the target gene mRNA to be degraded or its translation to be inhibited, ultimately achieving the effect of inhibiting the expression of the target gene. In recent years, RNAi has been considered a new and safe green pest management strategy, which is of great significance for the development of environmentally friendly agriculture and the control of disease-carrying insects. However, due to the electrostatic repulsion on the surface of the anionic cell membrane, the main limitation of introducing exogenous small interfering RNA is that it is difficult to diffuse passively through the cell membrane; at the same time, exogenous small interfering RNA is easily degraded and is unstable in nature.

[0003] The study of nanocarrier systems is a new direction in the field of pharmaceutical formulation. By combining the unique effects of nanoparticles with the characteristics of the drugs themselves, nanomedicines possess unique properties. For example, nanocarrier systems can significantly enhance drug accumulation at the target site through size effects, targeted modification, or responsiveness to the lesion microenvironment. They can also achieve controlled drug release and reduce side effects. Furthermore, for easily degradable drugs such as small interfering RNA, DNA, and protein drugs, nanodrug carriers can protect them from degradation, preventing premature contact with the biological environment, maintaining drug activity, and improving efficacy. These factors contribute to the widespread interest and attention in the use of nanotechnology for drug delivery. However, conventional nanoaqueous solutions have poor adhesion to plant surfaces and easily slide off, resulting in the waste of most of the active ingredients and poor results in actual field applications. Summary of the Invention

[0004] In response to the above-mentioned prior art, the present invention aims to provide a nano-hydrogel formulation for encapsulating small interfering RNA (siRNA) and its preparation method. This invention utilizes gold nanoparticles and dendritic mesoporous silica nanoparticles as a composite carrier to load the siRNA, which is then encapsulated with a pectin solution. The resulting nano-hydrogel formulation significantly enhances drug adhesion, enabling rapid drug penetration and targeted delivery.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect of the present invention, a nano-hydrogel preparation encapsulating small interfering RNA is provided, which is prepared by the following method:

[0007] (1) mixing a polyethyleneimine solution and polyethylene glycol-stabilized gold nanoparticles, adding small interfering RNA, and then adding the polyethyleneimine solution to obtain a gold nanoparticle-loaded small interfering RNA nanopesticide;

[0008] (2) mixing the small interfering RNA nanopesticide loaded with gold nanoparticles with dendritic mesoporous silica, stirring, collecting the precipitate by centrifugation, and washing to obtain the RNAi nanopesticide mediated by dendritic mesoporous silica and gold nanoparticles;

[0009] (3) The RNAi nanopesticide is dispersed in a pectin solution and encapsulated to prepare a nanohydrogel preparation encapsulating small interfering RNA.

[0010] Preferably, in step (1), the concentration of the polyethyleneimine solution is 0.1-2 mg / mL. The polyethyleneimine acts as a positive electrolyte and can adsorb small interfering RNA onto the surface of gold nanoparticles.

[0011] Preferably, in step (1), the polyethylene glycol-stabilized gold nanoparticles are prepared by the following method:

[0012] The polyethylene glycol solution was added dropwise to the gold nanoparticles, stirred for 2-3 hours, centrifuged, and washed to prepare polyethylene glycol-stabilized gold nanoparticles.

[0013] The above treatment of gold nanoparticles with polyethylene glycol can prevent the aggregation of gold nanoparticles and enhance their stability in solution.

[0014] Preferably, in step (2), the ratio of the added amount of the gold nanoparticle-loaded small interfering RNA solution to the added amount of the dendritic mesoporous silica is 1 mL: (8-12) mg.

[0015] Preferably, in step (2), the dendritic mesoporous silica is prepared by the following method:

[0016] Triethanolamine, hexadecyltrimethylammonium bromide and sodium salicylate are mixed and stirred for reaction for 0.5-1.5 hours, tetraethyl orthosilicate is added, and the stirring reaction is continued for 1.5-2.5 hours. The mixture is centrifuged, the precipitate is collected and washed, and then a methanol solution containing concentrated hydrochloric acid is added to remove the template. The mixture is washed and dried to prepare dendritic mesoporous silica.

[0017] More preferably, the ratio of the added amounts of triethanolamine, hexadecyltrimethylammonium bromide, sodium salicylate and tetraethyl orthosilicate is (0.1-0.2) mL: (0.5-1.0) g: (0.2-0.4) g: (6-10) mL.

[0018] Preferably, in step (3), the concentration of the pectin solution is 0.1-10 g / L; the ratio of the added amount of RNAi nanopesticide to the pectin solution is (1-10) mg: (10-100) mL.

[0019] Preferably, in step (3), the conditions for the encapsulation treatment are: adjusting the pH of the system to 4.0-4.5, and magnetic stirring overnight.

[0020] The second aspect of the present invention provides the use of the above-mentioned nanohydrogel preparation encapsulating small interfering RNA in the following (1) or (2):

[0021] (1) Prevent and control stem-boring pests;

[0022] (2) Preparation of products for controlling stem borers.

[0023] In the above application, the trunk-boring pests include but are not limited to: longhorn beetles, wood borers, jellyfish, bark beetles and weevils.

[0024] Beneficial effects of the present invention:

[0025] (1) The nano-hydrogel preparation of the present invention utilizes dendritic mesoporous silica nanoparticles and gold nanoparticles to jointly load small interfering RNA, which significantly improves the encapsulation effect of small interfering RNA; and can also stably and slowly release small interfering RNA in the environment.

[0026] (2) The nano-hydrogel preparation of the present invention is encapsulated with pectin solution, which can enhance the adhesion performance of the agent and can be widely applied through spraying, smearing, flying and other measures; and pectin is similar to and soluble in the xylem of trees, can activate tissue cells, promote absorption and conduction, and achieve efficient, safe, green and sustainable development of agricultural and forestry pests and diseases. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 : Electron micrographs of gold nanoparticles (A), dendritic mesoporous silica nanoparticles (B), and RNAi nanobiopesticide mediated by dendritic mesoporous silica and gold nanoparticles (C) prepared by the present invention.

[0028] Figure 2 : X-ray photoelectron spectroscopy analysis diagrams of NC-Cy3-siRNA, Au-PEG@PRP NPs and Au-PEG@PRP@DMSNs NPs prepared in the present invention.

[0029] Figure 3 : Infrared spectrum analysis of DMSNs and Au-PEG@PRP@DMSNs NPs prepared in the present invention.

[0030] Figure 4: Sustained release curves of small interfering RNA from Au-PEG@PRP@DMSNs NPs prepared in the present invention at temperature conditions of 15°C (A), 25°C (B), and 35°C (C) and different pH conditions (pH = 6.0, 7.4, and 8.2).

[0031] Figure 5 : Super depth of field and magnified images of Monochamus alternatus larvae treated with the nano-hydrogel preparation prepared by the present invention (EG) and the control group (CK); in the figure, A is the mouthparts, B is the body wall, and C is the stomata.

[0032] Figure 6 : Fluorescent image of the body wall of Monochamus alternatus larvae treated with the nano-hydrogel preparation prepared by the present invention.

[0033] Figure 7 : Relative expression levels of MaCDA2b gene after contact killing of Monochamus alternatus larvae by Au-PEG@PRP@DMSNs NPs at different concentrations.

[0034] Figure 8 : Survival rate of Monochamus alternatus larvae after contact treatment with different concentrations of Au-PEG@PRP@DMSNs NPs.

[0035] Figure 9 : Comparison of the phenotypes of Monochamus alternatus larvae after contact treatment; in the figure, A, B, and C are the phenotypes of Monochamus alternatus larvae in the CK group; a, b, and c are the phenotypes of Monochamus alternatus larvae in the contact treatment group. DETAILED DESCRIPTION

[0036] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0037] Terminology Notes:

[0038] The "room temperature" in the present invention refers to a temperature of 15°C to 35°C.

[0039] As previously mentioned, RNAi is considered a novel, safe, and green pest management strategy, with significant implications for understanding insect biology, developing environmentally friendly agriculture, and controlling disease-carrying insects. However, a major limitation of introducing exogenous small interfering RNA is the difficulty of passively diffusing through the cell membrane due to electrostatic repulsion on the surface of anionic cell membranes. Furthermore, exogenous small interfering RNA is highly susceptible to degradation and unstable, limiting its application in RNAi-based pest management. Conventional nano-aqueous agents exhibit poor adhesion to plant surfaces and easily slip, resulting in a significant waste of the active ingredient and poor results in actual field applications.

[0040] Based on this, the present invention has developed a new nanohydrogel formulation for encapsulating small interfering RNA. The present invention first uses polyethyleneimine to treat polyethylene glycol-stabilized gold nanoparticles, complexing the small interfering RNA to the surface of the gold nanoparticles through the interaction between positive and negative charges. Dendritic mesoporous silica nanoparticles are then dispersed therein, and the small interfering RNA loaded on the gold nanoparticles is physically adsorbed into the ultra-large pores of the dendritic mesoporous silica, achieving the co-loading of the small interfering RNA by the dendritic mesoporous silica and gold nanoparticles. Compared with using gold nanoparticles or dendritic mesoporous silica alone to load small interfering RNA, the co-loading of small interfering RNA by dendritic mesoporous silica and gold nanoparticles has a synergistic effect on the encapsulation effect (encapsulation efficiency and loading rate) of small interfering RNA.

[0041] Furthermore, the present invention co-loads small interfering RNA with dendritic mesoporous silica and gold nanoparticles and encapsulates them with a pectin solution. The property of pectin to form a hydrogel under acidic conditions is utilized to encapsulate and prepare a nano hydrogel preparation. Through the encapsulation of the pectin solution, the preparation has good adhesion and can release small interfering RNA in a controlled manner. It is suitable for preventing and controlling agricultural and forestry pests and diseases, and can be widely used through spraying, smearing, flying and other measures to achieve efficient, safe, green and sustainable development of agricultural and forestry pests and diseases.

[0042] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below with reference to specific embodiments.

[0043] The test materials used in the examples of the present invention are all conventional test materials in the field and can be purchased through commercial channels. Experimental methods without detailed conditions were carried out in accordance with conventional test methods or the operating instructions recommended by the supplier.

[0044] The CAS number of polyethylene glycol is 25322-68-3; the CAS number of polyethyleneimine is 9002-98-6; the CAS number of pectin is 9000-69-5.

[0045] The sequence of the small interfering RNA that interferes with the chitin deacetylase gene (MaCDA2b, GenBank: KY914480.1) of Monochamus alternatus is:

[0046] Sense:GCUCCUACGACGAUUGGUU(dT)(dT)

[0047] Antisense:AACCAUCGUCGUAGGAGC(dT)(dT)

[0048] Example 1: Preparation of Nanohydrogel Formulation Encapsulating Small Interfering RNA

[0049] 1. Preparation of small interfering RNA nanopesticides loaded with gold nanoparticles:

[0050] (1) Add 50 mL of 0.01% (mass fraction) chloroauric acid solution to a three-necked round-bottom flask, place it in an oil bath at 160°C and stir magnetically for 30 min until the liquid boils. Add 1.5 mL of 1% (mass fraction) trisodium citrate solution and react for 20 min. When the solution turns bright red, remove it and place it in ice water to cool to room temperature to obtain gold nanoparticles.

[0051] (2) 2.5 mL of 0.5 mg / mL polyethylene glycol solution was added dropwise to the gold nanoparticles, magnetically stirred for 2 h, centrifuged (4 °C, 14,000 rpm, 30 min), and washed three times with ultrapure water to remove excess polyethylene glycol to obtain polyethylene glycol-stabilized gold nanoparticles (Au-PEG).

[0052] (3) Take 50 mL of the polyethylene glycol-stabilized gold nanoparticles prepared above, add 25 mL of polyethyleneimine solution (1 mg / mL), and sonicate in an ice bath for 30 min. Centrifuge and wash three times with DEPC water to remove excess polyethyleneimine.

[0053] (4) Add 100 μg of small interfering RNA that interferes with the chitin deacetylase gene of Monochamus alternatus (MaCDA2b, GenBank: KY914480.1) to the system of step (3), sonicate in an ice bath in the dark for 30 min, centrifuge, and wash twice with DEPC water to remove free small interfering RNA.

[0054] (5) Add 50 ml of polyethyleneimine solution (1 mg / mL) to the system of step (4) above, and sonicate in an ice bath in the dark for 30 min. Centrifuge and wash three times with deionized water to obtain gold nanoparticle-loaded small interfering RNA nanopesticide (Au-PEG@PRPNPs).

[0055] 2. Preparation of dendritic mesoporous silica nanoparticles:

[0056] To a three-necked round-bottom flask, 50 mL of purified water and 121.6 μL of triethanolamine were added, incubated at 80°C, and reacted with magnetic stirring for 30 minutes. 0.76 g of hexadecyltrimethylammonium bromide and 0.336 g of sodium salicylate were added, and the reaction was continued with stirring for 1 hour. 8 mL of tetraethyl orthosilicate was added, and the reaction was continued with stirring for 2 hours. The mixture was centrifuged (4°C, 11,000 rpm, 30 minutes), and the precipitate was washed twice with anhydrous ethanol to remove unreacted material. A methanol solution containing 1.54 mL of concentrated hydrochloric acid (120 mL of methanol) was added to the precipitate, and the mixture was incubated in a 60°C water bath for 6 hours. This process was repeated three times to remove the template. The precipitate was washed twice with methanol to remove any residual hydrochloric acid, yielding a white precipitate. The white precipitate was transferred to an aqueous phase and freeze-dried to produce dendritic mesoporous silica nanoparticles (DMSNs).

[0057] 3. Preparation of RNAi nanopesticides mediated by dendritic mesoporous silica and gold nanoparticles:

[0058] Take 10 mg of the dendritic mesoporous silica nanoparticles (DMSNs) prepared in step 2 above and disperse them in 5 mL of DEPC water. Add 1 mL of the gold nanopesticide loaded with small interfering RNA (Au-PEG@PRP NPs) prepared in step 1, and stir magnetically at room temperature for 12 h. Centrifuge (4 ° C, 11000 rpm, 30 min), and wash the precipitate twice with DEPC water to obtain RNAi nanopesticide mediated by dendritic mesoporous silica and gold nanoparticles (Au-PEG@PRP@DMSNs NPs).

[0059] 4. Preparation of nanohydrogel preparations encapsulating small interfering RNA:

[0060] 10 mg of the dendritic mesoporous silica prepared above and the gold nanoparticle-mediated RNAi nanobiopesticide (Au-PEG@PRP@DMSNs NPs) were dispersed in 100 mL of 1 g / L pectin solution, the pH of the system was adjusted to 4.5, and magnetic stirring was performed overnight to obtain a nanohydrogel preparation encapsulating small interfering RNA.

[0061] Test Example 1:

[0062] 1. Electron microscopy analysis:

[0063] The gold nanoparticles, dendritic mesoporous silica nanoparticles, and dendritic mesoporous silica and gold nanoparticle-mediated RNAi nanopesticides prepared in Example 1 were observed by electron microscopy. Figure 1 shown.

[0064] 2. X-ray photoelectron spectroscopy analysis:

[0065] To facilitate analysis, the small interfering RNA in Example 1 was fluorescently labeled (NC-Cy3-siRNA), and the rest of the preparation method was the same as in Example 1.

[0066] X-ray photoelectron spectroscopy was performed on NC-Cy3-siRNA, as well as the prepared Au-PEG@PRP NPs and Au-PEG@PRP@DMSNs NPs; the results are shown in Figure 2. Figure 2 As shown, the presence of P, Au, Si, and C signals indicates the successful formation of Au-PEG@PRP@DMSNs NPs. The 84.11 eV peak of Au 4f confirms the presence of Au, the 103.7 eV peak of Si2p confirms the presence of Si, and the 126.5 eV peak of P2p confirms the presence of P element, indicating the successful loading of siRNA.

[0067] 3. Infrared spectrum analysis:

[0068] The DMSNs and Au-PEG@PRP@DMSNs NPs prepared in Example 1 were analyzed by infrared spectroscopy; the results are as follows Figure 3 As shown in the FT-IR image of DMSNs NPs, the Si-O-Si antisymmetric stretching vibration peak appears at 1091.56 cm -1 1631.61cm -1 It is the absorption characteristic peak of C=C. The characteristic peaks of the curve of Au-PEG@PRP@DMSNs NPs show all the characteristic peaks of DMSNs, which proves the successful combination of siRNA and Au-PEG@DMSNs NPs.

[0069] Test Example 2:

[0070] The Au-PEG@PRP@DMSNs NPs prepared in Example 1 were dispersed in PBS buffer solutions with pH values ​​of 6.0, 7.4, and 8.2 and incubated in an oscillating oven at 15, 25, and 35°C. After a predetermined time, 200 μL of the sample suspension was centrifuged to obtain the supernatant. The siRNA concentration in the supernatant was measured using an ultramicrospectrophotometer, and the cumulative siRNA release rate was calculated.

[0071] The results are as follows Figure 4 As shown in the data, the siRNA in the Au-PEG@PRP@DMSNs NPs prepared by the present invention can achieve a sustained and controlled release effect, and there is no sudden release during the entire sustained release process, indicating that Au-PEG@PRP@DMSNs NPs can achieve the effect of increasing the duration of siRNA; the release of siRNA in Au-PEG@PRP@DMSNs NPs does not change significantly with temperature and pH, indicating that it can be stably released in the environment.

[0072] Test Example 3:

[0073] In order to investigate the effect of the nano-hydrogel preparation encapsulating small interfering RNA prepared by the present invention on Monochamus alternatus larvae, the small interfering RNA in Example 1 was fluorescently labeled (NC-Cy3-siRNA), and the nano-hydrogel preparation encapsulating small interfering RNA was prepared according to the method of Example 1.

[0074] The prepared nanohydrogel preparation encapsulating small interfering RNA was sprayed on the body surface of the fourth-instar pine beetle larvae as the treatment group (EG); the pine beetle larvae without any treatment were used as the control group (CK); the coverage, permeability and adhesion of the nanohydrogel preparation encapsulating small interfering RNA on the pine beetle larvae were observed using a super depth of field microscope.

[0075] The results are as follows Figure 5 As shown in the figure, compared with the control group, the mouthparts, body wall and stomata of the pine sawyer beetle larvae in the treatment group were obviously attached with nanoparticles, and the magnified image could more clearly observe the nanoparticles with obvious distribution on the body wall and stomata, which proved that the nanohydrogel preparation encapsulating small interfering RNA prepared by the present invention had good distribution and adhesion properties on the body surface of the pine sawyer beetle larvae.

[0076] The larvae of Monochamus alternatus in the treatment group were observed using a stereofluorescence microscope. Figure 6 As shown in A, the nanohydrogel preparation encapsulated with NC-Cy3-siRNA exhibited obvious red fluorescence, proving that siRNA was successfully encapsulated. Figure 6 As shown in B, the body wall of Monochamus alternatus larvae treated with the nano-hydrogel preparation has obvious red fluorescence, and the magnified image can more clearly observe the fluorescent nanoparticles attached to the body wall ( Figure 6 C). At the same time, there are multiple independent bright fluorescent particles distributed around the stomata on the side of the larvae ( Figure 6 D), the magnified image clearly shows strong red fluorescence distributed across the stomata. This corresponds to the ultra-depth-of-field microscopy observations showing the distribution of nanoparticles within the insect's body wall and stomata, demonstrating the excellent distribution of the nanohydrogel formulation within Monochamus alternatus larvae.

[0077] The fluorescence distribution in the intestinal tissue was observed to study the distribution and retention of the nanohydrogel formulation in the intestinal tissue, e.g. Figure 6 As shown in E, the entire outline of the intestinal tissue in the cross-section of the midgut of the pine alternating beetle larvae exhibits uniformly distributed fluorescence, indicating that the nanohydrogel formulation can successfully reach the intestinal tissue. This proves that the nanohydrogel formulation of the present invention can achieve the encapsulation of (MaCDA2b-siRNA) that interferes with the chitin deacetylase gene of the pine alternating beetle and enter the insect body, achieving high permeability delivery from the body wall of the stem-boring pest pine alternating beetle to the target cells.

[0078] Test Example 4:

[0079] The Au-PEG@PRP@DMSNs NPs prepared in Example 1 were prepared into three different concentrations of 4 μg / mL, 8 μg / mL, and 16 μg / mL, respectively. The four-instar pine sawyer beetle larvae were sprayed with equal volumes of 4 μg / mL, 8 μg / mL, and 16 μg / mL of Au-PEG@PRP@DMSNs NPs for contact killing (CT), and the same volume of water was sprayed as a control (CK).

[0080] After 72 hours of treatment, the relative expression level of MaCDA2b gene (GenBank: KY914480.1) was determined by fluorescence quantitative analysis. Figure 7 As shown in the figure, the relative expression level of MaCDA2b gene in Monochamus alternatus larvae was downregulated to varying degrees under the treatment of different concentrations of Au-PEG@PRP@DMSNs NPs (4 μg / mL, 8 μg / mL, 16 μg / mL).

[0081] After contact killing, the phenotype of Monochamus alternatus larvae was observed and the number of dead and surviving Monochamus alternatus larvae was recorded. Figure 8 As shown in the figure, the entire lethal process can last for 14 days, which is related to the slow-release effect of the prepared Au-PEG@PRP@DMSNs NPs on siMaCDA2b, which can prolong the drug's duration of effect in the worm.

[0082] The fourth-instar Monochamus alternatus larvae in the CK group molted and split from the head molting line, breaking away from the old epidermis at the cracks in the order from the head to the tail ( Figure 9 A, B, and C); while the contact treatment (CT) showed abnormal molting and mortality, specifically: the entire old epidermis of the tested Monochamus alternatus larvae began to wrinkle and shrink and could not be removed from the body surface ( Figure 9 a); or the larvae of the tested longhorn beetle cracked from the thoracic plate, with a deformed head and the old epidermis of the tail not completely shed ( Figure 9 b); or the old cuticle of the tested longhorn beetle larvae breaks off from the head and sheds to the abdomen, but fails to completely shed the old cuticle ( Figure 9 c).

[0083] The above results show that the Au-PEG@PRP@DMSNs NPs prepared in the present invention have a good control effect on the larvae of pine sawyer beetles.

[0084] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A nano hydrogel preparation encapsulating small interfering RNA, characterized in that: Prepared by the following method: (1) mixing a polyethyleneimine solution and polyethylene glycol-stabilized gold nanoparticles, adding small interfering RNA, and then adding the polyethyleneimine solution to obtain a gold nanoparticle-loaded small interfering RNA nanopesticide; (2) mixing the small interfering RNA nanopesticide loaded with gold nanoparticles with dendritic mesoporous silica, stirring, collecting the precipitate by centrifugation, and washing to obtain the RNAi nanopesticide mediated by dendritic mesoporous silica and gold nanoparticles; (3) The RNAi nanopesticide is dispersed in a pectin solution and encapsulated to prepare a nanohydrogel preparation encapsulating small interfering RNA.

2. The nano hydrogel preparation encapsulating small interfering RNA according to claim 1, characterized in that In step (1), the concentration of the polyethyleneimine solution is 0.1-2 mg / mL.

3. The nano hydrogel preparation encapsulating small interfering RNA according to claim 1, characterized in that In step (2), the ratio of the added amount of the gold nanoparticle-loaded small interfering RNA solution to the dendritic mesoporous silica is 1 mL: (8-12) mg.

4. The nano hydrogel preparation encapsulating small interfering RNA according to claim 1, characterized in that In step (2), the dendritic mesoporous silica is prepared by the following method: Triethanolamine, hexadecyltrimethylammonium bromide and sodium salicylate are mixed and stirred for reaction for 0.5-1.5 hours, tetraethyl orthosilicate is added, and the stirring reaction is continued for 1.5-2.5 hours. The mixture is centrifuged, the precipitate is collected and washed, and then a methanol solution containing concentrated hydrochloric acid is added to remove the template. The mixture is washed and dried to prepare dendritic mesoporous silica.

5. The nano hydrogel preparation encapsulating small interfering RNA according to claim 4, characterized in that The ratio of the added amounts of triethanolamine, hexadecyltrimethylammonium bromide, sodium salicylate and tetraethyl orthosilicate is (0.1-0.2) mL: (0.5-1.0) g: (0.2-0.4) g: (6-10) mL.

6. The nano hydrogel preparation encapsulating small interfering RNA according to claim 1, characterized in that In step (3), the concentration of the pectin solution is 0.1-10 g / L; the ratio of the added amount of RNAi nanopesticide to the pectin solution is (1-10) mg: (10-100) mL.

7. The nano hydrogel preparation encapsulating small interfering RNA according to claim 1, characterized in that In step (3), the encapsulation treatment conditions are: adjusting the pH of the system to 4.0-4.5 and magnetic stirring overnight.

8. Use of the nanohydrogel preparation encapsulating small interfering RNA according to any one of claims 1 to 7 in the following (1) or (2): (1) Prevent and control stem-boring pests; (2) Preparation of products for controlling stem borers.

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