Laccase-responsive termite-killing nano capsule as well as preparation method and application thereof

Abstract

The invention discloses a laccase-responsive termite-killing nano capsule as well as a preparation method and application thereof. The preparation method comprises the following steps: dissolving the imidacloprid powder in a cosolvent to obtain an imidacloprid solution, dispersing the carboxylated organic metal framework in the cosolvent to obtain an organic metal framework solution, mixing and stirring the two obtained solutions, and then centrifugally drying to obtain the imidacloprid nano-capsule. An imidacloprid-loaded carboxylated organic metal framework is obtained; the preparation method comprises the following steps: preparing a nano capsule, dissolving the nano capsule in a citric acid buffer solution, adding an aqueous solution of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and an aqueous solution of N-hydroxysuccinimide, adding an aqueous solution of sodium lignin sulfonate, stirring, centrifuging and drying to obtain the nano capsule. The nano capsule provided by the invention can be specifically released under the action of laccase in intestinal tracts of termites, can be directly sprayed on body surfaces of the termites, cannot cause quick knockdown of the termites, and has a good virus transmission effect.

Description

Technical Field

[0001] The invention relates to the technical field of nano material synthesis, and in particular to a method for synthesizing a laccase-responsive termite-killing nano capsule material and an application thereof in preventing and controlling termites. Background Art

[0002] Termites are recognized as important agricultural and forestry pests worldwide, causing serious economic losses to human production and life. So far, chemical control is still the main means of termite control, but most of the chemical pesticides are lost in the fields during use, and long-term use will also have a serious impact on non-target organisms and the ecological environment.

[0003] Stimuli-responsive pesticide delivery systems based on nanotechnology show great potential in improving the efficacy and safety of pesticides. Therefore, the development and application of nanopesticides have received widespread attention. Among them, metal organic frameworks (MOFs) have the characteristics of large specific surface area, adjustable pores and modifiable surface, and are therefore widely used in gas storage and separation, molecular sensing, drug delivery systems, water pollutant remediation and catalysis. Yao et al. (Research Progress on Antibacterial Properties of Metal Organic Framework (MOF)-Based Hydrogels, [J]. Journal of Chemical Engineering, 2024, 487, 150641.) discussed the application of MOF-based antibacterial hydrogels in wound treatment and food packaging.

[0004] However, the existing metal framework lacks the ability to control the release of pesticides, which may lead to deficiencies in improving the efficiency of pesticide use and reducing the negative impact of pesticides. Therefore, how to improve the efficiency of nanopesticide use and reduce the harm caused by nanopesticides to the environment is an urgent problem to be solved. Summary of the invention

[0005] The technical problem to be solved by the present invention is how to prepare a termite nanocapsule material that responds to laccase, in order to solve the problems of drug loss, non-target accumulation and environmental pollution when chemical pesticides are used to control termites in the wild. Therefore, a method for synthesizing a termite nanocapsule material that responds to laccase and its application in controlling termites are proposed. While effectively controlling termites, the use efficiency of nanopesticides is improved, and the goal of being very environmentally friendly is achieved.

[0006] The present invention solves the above technical problems through the following technical solutions:

[0007] 1. Laccase-responsive termite-killing nanocapsules:

[0008] The termite-killing nanocapsule of the present invention is mainly prepared from imidacloprid powder (IMI), organic metal framework (MOF, UiO-66-COOH) and sodium lignin sulfonate (SL).

[0009] The mass relationship between the organic metal framework and sodium lignin sulfonate is 1:2-4.

[0010] The mass of the imidacloprid powder is 30 to 100 mg / kg of the total mass of the termite-killing nanocapsule.

[0011] The particle size of the carboxylated organic metal framework is 108 nm, and the pore size of the internal mesopores is 6.59 nm.

[0012] 2. A method for preparing laccase-responsive termite-killing nanocapsules, the method comprising the following steps:

[0013] S1. Dissolving imidacloprid powder in a first cosolvent to obtain an imidacloprid solution with a concentration of 5 to 50 mg / mL; preferably, the mass ratio of imidacloprid powder to the first cosolvent is 1:40.

[0014] S2, dispersing the carboxylated organic metal framework in the first co-solvent and ultrasonicating for 10 minutes to obtain an organic metal framework solution with a concentration of 0.5 to 6.25 mg / mL, and stirring at room temperature;

[0015] S3, mixing the imidacloprid solution described in step S1 and the organic metal framework solution described in step S2 with stirring for 24 hours, and obtaining a carboxylated organic metal framework loaded with imidacloprid after centrifugal drying;

[0016] Preferably, the carboxylated organic metal framework and imidacloprid original drug are dissolved in a first cosolvent, and the drug-loaded organic metal framework is obtained by stirring and centrifugal drying.

[0017] S4. Dissolve the carboxylated organic metal framework loaded with imidacloprid described in step S3 in a citric acid buffer solution, then add an aqueous solution of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride EDC and an aqueous solution of N-hydroxysuccinimide NHS, and finally add an aqueous solution of sodium lignin sulfonate. After stirring and centrifugal drying, the responsive laccase material IMI@UiO-66@SL loaded with imidacloprid is obtained, that is, the termite-killing nanocapsule is obtained, and the termite nanocapsule is a powder.

[0018] Since the external carboxyl groups of the organic metal framework react with the hydroxyl groups of sodium lignin sulfonate through ester bonds to generate a material that can respond to laccase, this material can accelerate the hydrolysis of sodium lignin sulfonate in the presence of laccase, thereby improving the release efficiency.

[0019] The first auxiliary solvent in steps S1 and S2 is anhydrous ethanol.

[0020] In the step S4, the volume ratio of the citric acid buffer, the aqueous solution of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride EDC, the aqueous solution of N-hydroxysuccinimide NHS and the aqueous solution of sodium lignin sulfonate is 2:1:1:4; the mass ratio relationship between the 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride EDC, N-hydroxysuccinimide NHS and sodium lignin sulfonate SL is: 575.1:345.27:300.

[0021] The carboxylated metal organic framework (MOF, UiO-66-COOH) was prepared in the following manner:

[0022] K1, dissolve zirconium tetrachloride ZrCl4 and trimellitic acid H3BTC in sterile double distilled water ddH 2 O to obtain a mixed solution;

[0023] K2. The mixed solution described in step K1 is placed in a reactor environment at 100° C. for reaction reflux for 24 hours to obtain a polymer, and then the polymer is centrifuged and dried under vacuum conditions for 24 hours to obtain a carboxylated organic metal framework (MOF, UiO-66-COOH) having a large specific surface area, controllable pores and modifiable surface.

[0024] 3. An application of the termite-killing nanocapsule in termite control.

[0025] 4. A method for killing termites using the termite killing nano capsule, the method comprising the following steps:

[0026] Q1. Add the termite-killing nanocapsule IMI@UiO-66@SL into distilled water, perform ultrasonic treatment for 10 minutes, and then place at room temperature for 5 minutes to obtain a termite-killing nanocapsule solution with a concentration of 0.2 to 5.0 ppm;

[0027] Q2. Place the termite-killing nanocapsule solution described in step Q1 in the termite living environment or directly apply it to the termites, so that the termites are exposed to the termite-killing nanocapsule solution. Then the nanocapsule solution enters the body of the termite. Since there is laccase in the termite intestine, the termite nanocapsule is specifically released under the action of laccase in the termite intestine.

[0028] More specifically, yellow-breasted Reticulitermes can be placed on dry filter paper containing a solution of the termite-killing nanocapsule IMI@UiO@66@SL at 28°C and observed for 5 days.

[0029] The beneficial effects of the present invention are:

[0030] 1. The present application utilizes a carboxylated organic metal framework and sodium lignin sulfonate to carry out an esterification reaction, and the sodium lignin sulfonate is coated on the outside of the carboxylated organic metal framework to form a material for preparing a laccase-responsive material.

[0031] 2. In the actual application of preventing and controlling termites, the laccase material of the present application is spread in the area where termites are infested, and the termites bring the material into the nest through their body surface or mouth. When the material is swallowed into the digestive tract by termites through feeding or cleaning behavior, the laccase in the termites will decompose the sodium lignin sulfonate outside the material, and the loaded drug will be released at this time, playing a role in killing termites. This has a certain protective effect on other non-target insects.

[0032] The product of the present invention can be directly sprayed on the surface of termites, has a slow effect, will not cause rapid knockdown of termites, and can complete 1-2 times of poison transmission, with a good poison transmission effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the synthesis of laccase-responsive termite-killing nanocapsules.

[0034] Figure 2 This is a Fourier transform infrared spectrum of the carboxylated organic metal framework obtained in Example 1 of the present application.

[0035] Figure 3 These are scanning electron microscopy images and transmission electron microscopy images of the carboxylated organic metal framework obtained in Example 1 of the present application.

[0036] Figure 4 This is a graph showing the particle size and internal pore size of the carboxylated organic metal framework obtained in Example 1 of the present application, wherein A represents the particle size and B represents the pore size.

[0037] Figure 5 This is a thermogravimetric diagram of the termite-killing nanocapsule obtained in Example 5 of the present application.

[0038] Figure 6 This is a graph showing the in vitro drug release rate of the termite-killing nanocapsules obtained in Example 5 of the present application.

[0039] Table 1 is a table showing the mortality of termites treated with cellulase materials at different concentrations in the examples of the present application.

[0040] Table 2 is a table showing the mortality of termites under treatment with different concentrations of products in the comparative examples of this application. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0043] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0044] Embodiments of the present invention are as follows:

[0045] Embodiment 1:

[0046] The synthesis process of laccase-responsive termite-killing nanocapsules Figure 1 As shown,

[0047] S1. 9.6 g zirconium tetrachloride (ZrCl 4 ) and 8.8 g trimellitic acid (H 3 BTC) add 200 mL of sterile double distilled water (ddH 2 O, reflux at 100 °C for 24 h, centrifuge and vacuum dry to obtain a carboxylated organic metal framework;

[0048] The product prepared in step S1 is subjected to Fourier transform infrared spectroscopy analysis, and the obtained spectrum is as follows: Figure 2 As shown in the figure, it can be seen that the absorption characteristic peak of Zr-O appears at 656cm-1; the absorption characteristic peak of Zr4+ and H 3 The characteristic absorption peak of aromatic C=C in BTC and the characteristic absorption peak of carboxylic acid carbonyl C=O appeared at 1587cm-1, which proved that the prepared material was in line with expectations.

[0049] The product prepared in step S1 was measured by scanning electron microscopy and transmission electron microscopy, and the results obtained were as follows: Figure 3 As shown, Figure 3 -A is a scanning electron microscope image, Figure 3 -B is a transmission electron microscope image. It can be seen that the material forms a nano-microsphere morphology with a hollow interior.

[0050] The particle size and internal pore size of the product prepared in step S1 were measured, and the results were as follows: Figure 4 As shown, Figure 3-A particle size is consistent with the electron microscopy results, which is about 108nm, and the pore size is Figure 3 -B shows that it is 6.59nm.

[0051] S2, dissolving the imidacloprid original drug of the required mass to meet the material drug loading amount in anhydrous ethanol of the corresponding mass ratio to obtain an imidacloprid solution with a concentration of 25 mg / mL;

[0052] S3, dispersing 500 mg of the carboxylated organic metal framework obtained in step S1 in anhydrous ethanol and ultrasonicating for 10 min to obtain an organic metal framework solution with a concentration of 6.25 mg / mL, and stirring at room temperature;

[0053] S4, mixing the imidacloprid solution obtained in step S2 and the organic metal framework solution obtained in step S3 at room temperature for 24 hours, and centrifugally drying to obtain a carboxylated organic metal framework loaded with imidacloprid;

[0054] S5. Dissolve the product in step S4 in citric acid buffer, add an aqueous solution of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and an aqueous solution of N-hydroxysuccinimide (NHS) to the solution, and finally add an aqueous solution of sodium lignin sulfonate (SL), and obtain a material responsive to imidacloprid loaded with laccase by stirring and centrifugal drying.

[0055] Example 2

[0056] This embodiment provides a synthesis method for increasing the drug loading of a material, which differs from Embodiment 2 in that the mass of imidacloprid accounts for 30 mg / kg of the total mass of the termite-killing nanocapsule.

[0057] Example 3

[0058] This embodiment provides a synthesis method for increasing the drug loading of a material, which differs from Embodiment 2 in that the mass of imidacloprid accounts for 40 mg / kg of the total mass of the termite-killing nanocapsule.

[0059] Example 4

[0060] This embodiment provides a synthesis method for increasing the drug loading of a material, which differs from Embodiment 2 in that the mass of imidacloprid accounts for 50 mg / kg of the total mass of the termite-killing nanocapsule.

[0061] Example 5

[0062] This embodiment provides a synthesis method for increasing the drug loading of a material, which differs from Embodiment 2 in that the mass of imidacloprid accounts for 60 mg / kg of the total mass of the termite-killing nanocapsule.

[0063] According to the method of Example 5, the prepared product was subjected to thermogravimetric analysis, and the thermogravimetric analysis curve was obtained as follows: Figure 5 As shown, according to the TG graph, the weight loss before 220°C may be caused by the evaporation of water, and the weight loss between 520°C and 800°C may be due to the decomposition and volatilization of imidacloprid. The loading rate of imidacloprid is about 7%.

[0064] According to the method of Example 5, the prepared product was subjected to an in vitro release test, and the in vitro release rate obtained was as follows: Figure 6 As shown, according to the release rate graph, when the pH is 7 and the stirring rate is 100 rpm / min, in the absence of laccase, the cumulative release rate of imidacloprid is 50.17% on the 5th day; in the presence of laccase, the cumulative release rate of imidacloprid is higher, reaching 74.97% on the 5th day.

[0065] According to the method of Example 5, the prepared product was used to test the biological activity of termites, and the biological activities of termites at different concentrations (0.2-5.0 mg / kg) of the product were shown in Table 1.

[0066] Table 1

[0067]

[0068]

[0069] According to the above Table 1, on the 5th day, the mortality rate of termites gradually increased with the increase of concentration.

[0070] Example 6

[0071] This embodiment provides a synthesis method for increasing the drug loading of a material, which differs from Embodiment 2 in that the mass of imidacloprid accounts for 70 mg / kg of the total mass of the termite-killing nanocapsule.

[0072] Example 7

[0073] This embodiment provides a synthesis method for increasing the drug loading of a material, which differs from Embodiment 2 in that the mass of imidacloprid accounts for 80 mg / kg of the total mass of the termite-killing nanocapsule.

[0074] Example 8

[0075] This embodiment provides a synthesis method for increasing the drug loading of a material, which differs from Embodiment 2 in that the mass of imidacloprid accounts for 90 mg / kg of the total mass of the termite-killing nanocapsule.

[0076] Example 9

[0077] This embodiment provides a synthesis method for increasing the drug loading of a material, which differs from Embodiment 2 in that the mass of imidacloprid accounts for 100 mg / kg of the total mass of the termite-killing nanocapsule.

[0078] Comparative Example 1

[0079] The carboxylated organic metal framework obtained in step S1 of Example 1 was used to perform the following treatment:

[0080] (1) dissolving 1 g of imidacloprid original drug in anhydrous ethanol to obtain an imidacloprid solution with a concentration of 25 mg / mL;

[0081] (2) dispersing 400 mg of the carboxylated organic metal framework in anhydrous ethanol and sonicating for 10 min to obtain an organic metal framework solution with a concentration of 6.25 mg / mL, and stirring at room temperature;

[0082] (3) mixing the imidacloprid solution obtained in step (1) and the organic metal framework solution obtained in step (2) at room temperature for 24 hours, and centrifugally drying to obtain a carboxylated organic metal framework loaded with imidacloprid;

[0083] Then, the termite biological activity test was carried out, and the termite biological activity of the product at different concentrations (0.2-5.0 mg / kg) was shown in Table 2.

[0084] Table 2

[0085]

[0086]

[0087] Comparing the termite biological activity results of Comparative Example 1 with those of Example 5, it can be seen that the material without the addition of sodium lignin sulfonate (SL) has a faster killing speed on termites and a faster release speed of imidacloprid, and has no better sustained-release effect.

[0088] Therefore, it can be seen that the material of the present invention without adding sodium lignin sulfonate (SL) has a faster release speed in the environment and a higher release rate; in addition, the toxic effect after adding sodium lignin sulfonate (SL) is sustained-release compared to that without adding sodium lignin sulfonate, and is safe and friendly to the environment.

Claims

1. A laccase-responsive termite-killing nanocapsule, characterized in that: It is mainly prepared from imidacloprid powder, organic metal framework and sodium lignin sulfonate.

2. The laccase-responsive termite-killing nanocapsule according to claim 1, characterized in that: The mass relationship between the organic metal framework and sodium lignin sulfonate is 1:2-4.

3. The laccase-responsive termite-killing nanocapsule according to claim 1, characterized in that: The mass of the imidacloprid powder is 30 to 100 mg / kg of the total mass of the termite-killing nanocapsule.

4. The laccase-responsive termite-killing nanocapsule according to claim 1, characterized in that: The particle size of the carboxylated organic metal framework is 108 nm, and the pore size of the internal mesopores is 6.59 nm.

5. The method for preparing the termite-killing nanocapsule according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: S1, dissolving the imidacloprid powder in the first cosolvent to obtain an imidacloprid solution with a concentration of 5 to 50 mg / mL; S2, dispersing the carboxylated organic metal framework in the first co-solvent and ultrasonicating for 10 minutes to obtain an organic metal framework solution with a concentration of 0.5 to 6.25 mg / mL, and stirring at room temperature; S3, mixing the imidacloprid solution described in step S1 and the organic metal framework solution described in step S2 with stirring for 24 hours, and obtaining a carboxylated organic metal framework loaded with imidacloprid after centrifugal drying; S4. Dissolve the carboxylated organic metal framework loaded with imidacloprid described in step S3 in a citric acid buffer solution, then add an aqueous solution of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride EDC and an aqueous solution of N-hydroxysuccinimide NHS, and finally add an aqueous solution of sodium lignin sulfonate. After stirring and centrifuging and drying, obtain the responsive laccase material loaded with imidacloprid, that is, obtain the termite-killing nanocapsule.

6. The method for preparing the termite-killing nanocapsule according to claim 5, characterized in that: The first auxiliary solvent in steps S1 and S2 is anhydrous ethanol.

7. The method for preparing the termite-killing nanocapsule according to claim 5, characterized in that: In the step S4, the volume ratio of the citric acid buffer, the aqueous solution of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride EDC, the aqueous solution of N-hydroxysuccinimide NHS and the aqueous solution of sodium lignin sulfonate is 2:1:1:4; the mass ratio relationship between the 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride EDC, N-hydroxysuccinimide NHS and sodium lignin sulfonate SL is: 575.1:345.27:

300.

8. The method for preparing the termite-killing nanocapsule according to claim 5, characterized in that: The carboxylated organic metal framework is prepared in the following manner: K1, dissolving zirconium tetrachloride ZrCl4 and trimellitic acid H3BTC in sterile double distilled water ddH2O in a mass ratio of 1.2:1.1 to obtain a mixed solution; K2. The mixed solution described in step K1 is placed in an environment of 100° C. for reaction reflux for 24 hours to obtain a polymer, and then the polymer is centrifuged and dried under vacuum conditions for 24 hours to obtain a carboxylated organic metal framework.

9. Use of the termite-killing nanocapsule according to any one of claims 1 to 4 or the termite-killing nanocapsule prepared by the preparation method according to any one of claims 5 to 8 in termite control.

10. A method for killing termites using the termite-killing nanocapsule according to any one of claims 1 to 4 or the termite-killing nanocapsule prepared by the preparation method according to any one of claims 5 to 8, characterized in that: The method comprises the following steps: Q1, adding the termite-killing nanocapsule to distilled water, ultrasonically treating for 10 minutes, and then placing at room temperature for 5 minutes to obtain a termite-killing nanocapsule solution with a concentration of 0.2 to 5.0 ppm; Q2. Place the termite-killing nanocapsule solution described in step Q1 in the termite living environment or directly apply it to the termites, so that the termites are exposed to the termite-killing nanocapsule solution, and then the nanocapsule solution enters the body of the termite, and the termite nanocapsule is specifically released in the termite intestine.

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