Layered double hydroxide-based biological pesticide controlled-release preparation, and preparation method and application thereof

Abstract

The present application relates to the technical field of pesticide slow-release material, and discloses a biological pesticide controlled-release preparation based on layered double hydroxide and a preparation method and application thereof.The biological pesticide controlled-release preparation based on layered double hydroxide comprises a layered double hydroxide material and biological pesticides loaded on the surface and internal pores of the layered double hydroxide material.The biological pesticide controlled-release preparation has excellent photolysis resistance and slow-release performance, the photodegradation performance thereof within 120 min is reduced by about 49.39%, the slow-release effect is greatly increased, and the long-acting insecticidal effect of the biological pesticide is improved.Further, the preparation method of the biological pesticide controlled-release preparation is low in cost and can be used for industrial production.

Description

Technical Field

[0001] This invention relates to the field of pesticide controlled-release materials technology, and in particular to a biopesticide controlled-release formulation based on layered double hydroxides, its preparation method and application. Background Technology

[0002] Dinotefuran is a third-generation neonicotinoid pesticide launched by Mitsui Chemicals, Inc. of Japan in 2002. Its chemical name is 1-methyl-2-nitro-3-(tetrahydro-3-furanmethyl)guanidine, and its molecular formula is C7H. 14 N4O3 has a molecular weight of 202.2111 g / mol. Fipronil can be applied through foliar, seed, and soil treatments to control pests such as rice planthoppers, thrips, aphids, and black-tailed leafhoppers. Fipronil inhibits acetylcholine receptors in insects, causing severe disruption to their central nervous system, interfering with normal nerve activity, interrupting nerve stimulation transmission, leading to extreme excitement, and eventually death from paralysis. Fipronil has contact, stomach poison, systemic, osmotic, and translocative effects; it is rapidly absorbed by the roots, stems, and leaves of plants and translocates upwards to all parts of the plant. Common formulations of fipronil include soluble granules, wettable powders, and water-dispersible granules. According to data from the China Pesticide Information Network, there are a total of 261 registered products for fipronil, of which 25 are technical grade products (9.58%), 83 are suspension concentrates (31.80%), 56 are water-dispersible granules (21.46%), and 24 are wettable powders (9.20%).

[0003] Related studies have shown that although traditional fipronil formulations are widely used in the field of insecticides, they still have two major drawbacks that limit their practical application in agricultural production. First, fipronil has high water solubility, reaching up to 40 g / L in water, making it easily lost with water and causing environmental pollution. In industrial production, large amounts of glycerol, urea, and other adjuvants need to be added to control the water solubility of fipronil technical, resulting in high costs and susceptibility to temperature-related phenomena such as crystallization and paste formation, reducing its practical effectiveness. Second, fipronil is easily degraded by light in the environment, limiting its long-lasting effect.

[0004] In recent years, in order to address the limitations of dinotefuran in agricultural production, researchers have begun to focus on the development of dinotefuran sustained-release formulations. Feng et al. (Pu Feng, Jinli Chen, Chaoran Fan, et al. An eco-friendly MIL-101@CMCS double-coated dinotefuran for long-acting active release and sustainable pest control. Journal of Cleaner Production, 2020, 265:121851) prepared a MOF (Metal-Organic Frameworks) dinotefuran sustained-release formulation, using MIL-101 and carboxymethyl chitosan as a double-layer shell. The carboxymethyl chitosan outer shell is suitable for early release, while the MIL-101 inner shell can be used for later release, thus achieving a longer duration of action. However, the synthesis of this formulation requires the use of a large amount of the organic solution N,N-dimethylamide, which can easily cause environmental harm. Given that most current sustained-release formulations of fipronil are still in the preliminary exploratory stage, and have not simultaneously addressed the drawbacks of fipronil's high solubility and photodegradation, while achieving controlled-release effects, the synthesis of an environmentally friendly, safe, water-soluble, and photodegradation-resistant controlled-release formulation of fipronil is of significant strategic importance. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a controlled-release formulation of a biopesticide based on layered double hydroxides, which has excellent resistance to photodegradation and sustained-release properties, and helps to improve the long-lasting insecticidal effect of biopesticides.

[0006] The present invention also proposes a method for preparing a controlled-release formulation of a biopesticide based on layered double hydroxides as described above.

[0007] The present invention also proposes the application of the above-mentioned controlled-release formulation of biopesticide based on layered double hydroxide and its preparation method in the preparation of pesticides.

[0008] In a first aspect, the present invention provides a controlled-release formulation of a biopesticide based on layered double hydroxides, comprising a layered double hydroxide material and a biopesticide loaded on the surface and internal pores of the layered double hydroxide material.

[0009] The controlled-release biopesticide formulation based on layered double hydroxides according to embodiments of the present invention has at least the following beneficial effects:

[0010] (1) The controlled-release formulation of biopesticide based on layered double hydroxide of the present invention consists of layered double hydroxide material and biopesticide loaded on the surface and internal pores of the layered double hydroxide material. The layered double hydroxide has a large specific surface area, good stability, and a controllable pore structure (which can be obtained by adjusting the preparation conditions), so that it can adapt to the needs of different biopesticide loading materials.

[0011] (2) The controlled-release formulation of biopesticide based on layered double hydroxide of the present invention has excellent resistance to photodegradation and sustained-release properties, which helps to improve the long-term insecticidal effect of biopesticide.

[0012] In some embodiments of the present invention, the layered double hydroxide material and the biopesticide loaded on the surface and internal pores of the layered double hydroxide material constitute the core of the biopesticide controlled-release formulation.

[0013] In some embodiments of the present invention, the biopesticide release formulation further includes a polydopamine shell and / or a zein shell.

[0014] Further coating the core surface, which consists of a layered double hydroxide material and a biopesticide loaded on the surface and internal pores of the layered double hydroxide material, with a polydopamine shell and / or a zein shell helps to further enhance the anti-photodegradation and sustained-release effects of the biopesticide controlled-release formulation.

[0015] When the coating layer is a polydopamine shell, the controlled-release formulation of the biopesticide exhibits pH sensitivity under different pH conditions. For example, under a weakly acidic environment (pH=5), the cumulative release of PDA / LDH@DNF in 1 hour can reach as high as 73.65%, while under neutral (pH=7) and weakly alkaline (pH=9) conditions, the cumulative release of PDA / LDH@DNF is only 46.75% and 18.33%, respectively. Therefore, by controlling the pH value in the environment, the release of biopesticides can be controlled in real time.

[0016] Furthermore, when the coating layer is a zein shell, the prepared controlled-release biopesticide exhibits enzyme-responsive release performance. That is, in a conventional protease-free environment, the release amount of biopesticide is low due to the presence of zein; however, when it enters the insect organisms being controlled, the release rate of biopesticide is greatly increased due to the degradation effect of proteases, which helps to quickly achieve the control effect and has important application value for promoting the efficient use of pesticides.

[0017] In some embodiments of the present invention, the biopesticide includes at least one of dinotefuran, glyphosate, imidacloprid, and 2,4-D class pesticides.

[0018] In some embodiments of the present invention, the biopesticide is fipronil.

[0019] In some embodiments of the present invention, the loading rate of the biopesticide is 1-20%.

[0020] In some embodiments of the present invention, the loading rate of the biopesticide is 4-20%.

[0021] In some embodiments of the present invention, the loading rate of the biopesticide is 5-20%.

[0022] In some embodiments of the present invention, the loading rate of the biopesticide is 9-16%.

[0023] In some embodiments of the present invention, the layered double hydroxide material is a layered bimetallic hydroxide material; preferably, it is at least one of magnesium-iron type layered bimetallic hydroxide material, copper-aluminum type layered bimetallic hydroxide material, zinc-aluminum type layered bimetallic hydroxide material, nickel-aluminum type layered bimetallic hydroxide material, calcium-aluminum type layered bimetallic hydroxide material, and magnesium-aluminum type layered bimetallic hydroxide material; more preferably, it is a magnesium-aluminum type layered bimetallic hydroxide material.

[0024] A second aspect of the present invention provides a method for preparing the controlled-release formulation of a biopesticide based on layered double hydroxides as described in the first aspect, comprising the following steps:

[0025] Step S1: Prepare a mixed solution A containing divalent and / or trivalent metal salts, anionic surfactants, and biological pesticides;

[0026] Step S2: Under an inert atmosphere, mix the mixed solution A, the alkaline solution and the metal salt solution, adjust the pH value to 8.5-9, react, separate the solid and liquid, collect the precipitate, and dry it to obtain the final product.

[0027] The preparation method according to embodiments of the present invention has at least the following beneficial effects: the controlled-release formulation of biopesticide based on layered double hydroxides prepared by the method of the present invention has good controllability of pesticide loading rate. By adjusting the concentration of each substance in the mixed solution A, biopesticide controlled-release formulations with different pesticide loading rates can be prepared, reducing the abuse rate of biopesticides. Secondly, the preparation method of the biopesticide controlled-release formulation of the present invention is simple and low in cost, and can be used for industrial production.

[0028] In some embodiments of the present invention, the drying process further includes:

[0029] The dried material was dispersed in a Tris-HCl solution, and then dopamine hydrochloride was added to obtain a solution of complex I. The reaction was carried out, and the solid phase was collected after solid-liquid separation.

[0030] In some embodiments of the present invention, the drying process further includes:

[0031] The mixture was mixed with an alcohol solvent containing a cationic detergent and zein to obtain a solution of complex II. The reaction was carried out, followed by solid-liquid separation, and the solid phase was collected.

[0032] In some embodiments of the present invention, the divalent metal salt includes at least one of divalent magnesium salt, divalent nickel salt, divalent copper salt, divalent calcium salt, and divalent zinc salt.

[0033] In some embodiments of the present invention, the divalent metal salt is a divalent magnesium salt, preferably magnesium chloride.

[0034] In some embodiments of the present invention, the trivalent metal salt solution includes at least one of trivalent aluminum salt, trivalent chromium salt, and trivalent iron salt.

[0035] In some embodiments of the present invention, the trivalent metal salt solution is a trivalent aluminum salt, preferably aluminum chloride.

[0036] In some embodiments of the present invention, the anionic surfactant includes at least one of sodium carboxymethyl cellulose, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and calcium dodecylbenzene sulfonate.

[0037] In some embodiments of the present invention, the anionic surfactant is sodium dodecyl sulfate.

[0038] In some embodiments of the present invention, the alcohol solvent is an ethanol solution or a methanol solution; preferably, the volume ratio of ethanol in the ethanol solution is 75% to 85%, and the volume ratio of methanol in the methanol solution is 75% to 85%.

[0039] In some embodiments of the present invention, the concentration of divalent and / or trivalent metal salts in the mixed solution A is 0.01 to 0.08 mol / L.

[0040] In some embodiments of the present invention, the concentration of divalent and / or trivalent metal salts in the mixed solution A is 0.02 to 0.06 mol / L.

[0041] In some embodiments of the present invention, the concentration of the anionic surfactant in the mixed solution A is 0.0001 to 0.0004 mol / L.

[0042] In some embodiments of the present invention, the concentration of the anionic surfactant in the mixed solution A is 0.0001 to 0.0002 mol / L.

[0043] In some embodiments of the present invention, the concentration of the biopesticide in the mixed solution A is 0.01 to 0.20 mol / L.

[0044] In some embodiments of the present invention, the concentration of the biopesticide in the mixed solution A is 0.01 to 0.18 mol / L.

[0045] In some embodiments of the present invention, the concentration of dopamine hydrochloride in the complex I solution is 0.5 to 3 mg / mL.

[0046] In some embodiments of the present invention, the concentration of dopamine hydrochloride in the complex I solution is 0.5 to 2.5 mg / mL.

[0047] In some embodiments of the present invention, the alkaline solution comprises NaOH solution and / or KOH solution. Preferably, the alkaline solution is NaOH solution.

[0048] In some embodiments of the present invention, the concentration of the NaOH solution is 0.1 to 0.2 mol / L.

[0049] In some embodiments of the present invention, the concentration of the NaOH solution is 0.1 to 0.15 mol / L.

[0050] In some embodiments of the present invention, the metal salt solution includes NaCl solution and / or KCl solution. Preferably, the metal salt solution is NaCl solution.

[0051] In some embodiments of the present invention, the concentration of the NaCl solution is 0.8 to 1.5 mol / L.

[0052] In some embodiments of the present invention, the concentration of the NaCl solution is 0.8–1.2 mol / L.

[0053] In some embodiments of the present invention, the mass ratio of the zein to the layered double hydroxide / biopesticide composite material in the complex II solution is 0.2 to 2.0:1.

[0054] In some embodiments of the present invention, the mass ratio of the zein to the layered double hydroxide / biopesticide composite material in the complex II solution is 0.2 to 1.5:1.

[0055] In some embodiments of the present invention, the pH value of the Tris-HCl solution is 8 to 8.6; preferably 8.2 to 8.6; more preferably 8.5.

[0056] In some embodiments of the present invention, the drying temperature is 55–65°C.

[0057] In some preferred embodiments of the present invention, the drying temperature is 60°C.

[0058] In some embodiments of the present invention, the drying time is 12 to 36°C.

[0059] In some preferred embodiments of the present invention, the drying time is 24°C.

[0060] In some embodiments of the present invention, unless otherwise specified, the solvent of the solution is water, preferably deionized water.

[0061] A third aspect of the present invention provides the application of the preparation method of the controlled-release biological pesticide formulation based on layered double hydroxides described in the first aspect or the controlled-release biological pesticide formulation based on layered double hydroxides described in the second aspect in the preparation of pesticides.

[0062] In some embodiments of the present invention, the pesticide includes a biological pesticide slow-release agent.

[0063] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0064] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0065] Figure 1 The images show the FTIR spectra of DNF, MgAl-LDHs, and LDH@DNF with different drug loading rates in embodiments of the present invention.

[0066] Figure 2 The images show the FTIR spectra of PDA / LDH@DNF coated with different dopamine hydrochloride in the embodiments of the present invention.

[0067] Figure 3 The images show the FTIR spectra of Zein / LDH@DNF coated with different zein proteins in embodiments of the present invention.

[0068] Figure 4 The images are SEM images, where a represents LDH; b represents LDH@DNF; c represents PDA / LDH@DNF; and d represents Zein / LDH@DNF.

[0069] Figure 5 This is a statistical chart showing the photodegradation rate of different pesticide formulations in the embodiments of the present invention.

[0070] Figure 6 This is a graph showing the statistical results of the mortality rate of fall armyworm larvae using different materials in an embodiment of the present invention.

[0071] Figure 7 The following are statistical results of DNF concentration in the leachate of different drug loading systems in embodiments of the present invention.

[0072] Figure 8 The leaching rate statistics are for different drug loading systems in the embodiments of the present invention. Detailed Implementation

[0073] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0074] The terms "preferred," "more preferably," etc., used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0075] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0076] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0077] In the description of this invention, magnesium chloride hexahydrate (MgCl2·6H2O) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., with product number M813913;

[0078] Aluminum chloride hexahydrate (AlCl3·6H2O) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., product number A801040;

[0079] Sodium chloride (NaCl) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., product number S805275;

[0080] Sodium hydroxide (NaOH) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., product number S817968;

[0081] Sodium dodecyl sulfate (C 12 H 25 SO4Na, SDS) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., product number S348686;

[0082] fipronil technical (C7H) 14 N4O3 (DNF) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., product number D832561;

[0083] Dopamine hydrochloride (C8H) 11 NO2·HCl was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., product number D806618;

[0084] Zein was purchased from Shanghai Maclean Biotechnology Co., Ltd., product number Z822847.

[0085] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0086] (I) LDH@DNF prepared from different fipronil

[0087] Example 1

[0088] This embodiment provides a method for preparing LDH material (LDH@DNF) loaded with DNF pesticide, specifically including the following steps:

[0089] Step S1: Prepare a mixed solution containing 0.04 mol / L MgCl2, 0.02 mol / L AlCl3, 0.0002 mol / L sodium dodecyl sulfate and 0.01 mol / L dinotefuran, denoted as solution A;

[0090] Step S2: Prepare a 0.12 mol / L NaOH solution, denoted as solution B.

[0091] Step S3: Prepare a NaCl solution with a concentration of 1 mol / L, denoted as solution C;

[0092] Step S4: Under the condition of N2 purging, slowly add solution A and solution B dropwise into solution C, adjust the pH of the solution to 8.5-9, continuously stir at room temperature and age with nitrogen gas for 2 hours, then obtain a white precipitate by multiple centrifugation and washing, and dry in a vacuum drying oven at 60℃ for 24 hours to obtain LDH@DNF.

[0093] Example 2

[0094] This embodiment provides a method for preparing LDH material (LDH@DNF) loaded with DNF pesticide. The difference between this method and Example 1 is that the concentration of fipronil in solution A is 0.02 mol / L, while the other conditions remain the same.

[0095] Example 3

[0096] This embodiment provides a method for preparing LDH material (LDH@DNF) loaded with DNF pesticide. The difference between this method and Example 1 is that the concentration of fipronil in solution A is 0.03 mol / L, while the other conditions remain the same.

[0097] Example 4

[0098] This embodiment provides a method for preparing LDH material (LDH@DNF) loaded with DNF pesticide. The difference between this method and Example 1 is that the concentration of fipronil in solution A is 0.04 mol / L, while the other conditions remain the same.

[0099] Example 5

[0100] This embodiment provides a method for preparing LDH material (LDH@DNF) loaded with DNF pesticide. The difference between this method and Example 1 is that the concentration of fipronil in solution A is 0.05 mol / L, while the other conditions remain the same.

[0101] Example 6

[0102] This embodiment provides a method for preparing LDH material (LDH@DNF) loaded with DNF pesticide. The difference between this method and Example 1 is that the concentration of fipronil in solution A is 0.06 mol / L, while the other conditions remain the same.

[0103] Example 7

[0104] This embodiment provides a method for preparing LDH material (LDH@DNF) loaded with DNF pesticide. The difference between this method and Example 1 is that the concentration of fipronil in solution A is 0.08 mol / L, while the other conditions remain the same.

[0105] Example 8

[0106] This embodiment provides a method for preparing LDH material (LDH@DNF) loaded with DNF pesticide. The difference between this method and Example 1 is that the concentration of fipronil in solution A is 0.10 mol / L, while the other conditions remain the same.

[0107] Example 9

[0108] This embodiment provides a method for preparing LDH material (LDH@DNF) loaded with DNF pesticide. The difference between this method and Example 1 is that the concentration of fipronil in solution A is 0.12 mol / L, while the other conditions remain the same.

[0109] Example 10

[0110] This embodiment provides a method for preparing LDH material (LDH@DNF) loaded with DNF pesticide. The difference between this method and Example 1 is that the concentration of fipronil in solution A is 0.14 mol / L, while the other conditions remain the same.

[0111] (II) Preparation of LDH@DNF materials from different layered double hydroxides

[0112] Example 11

[0113] This embodiment provides a method for preparing LDH material (LDH@DNF) loaded with DNF pesticide. The difference between this method and Example 9 is that MgCl2 in solution A is replaced with CaCl2, while the rest of the additives remain the same.

[0114] Example 12

[0115] This embodiment provides a method for preparing an LDH material (LDH@DNF) loaded with DNF pesticide. The difference between this method and Example 9 is that AlCl3 in solution A is replaced with FeCl3, while the rest of the additives remain the same.

[0116] (III) PDA / LDH@DNF coated with different dopamine hydrochloride

[0117] Example 13

[0118] This embodiment provides a method for preparing PDA / LDH@DNF, specifically including the following steps:

[0119] Step S1: Prepare a mixed solution containing 0.04 mol / L MgCl2, 0.02 mol / L AlCl3, 0.0002 mol / L sodium dodecyl sulfate and 0.12 mol / L dinotefuran, denoted as solution A;

[0120] Step S2: Prepare a 0.12 mol / L NaOH solution, denoted as solution B.

[0121] Step S3: Prepare a NaCl solution with a concentration of 1 mol / L, denoted as solution C;

[0122] Step S4: Under the condition of N2 introduction, slowly add solution A and solution B dropwise into solution C, adjust the pH of the solution to 8.5-9, stir continuously, age for 2 hours, and then obtain a white precipitate by multiple centrifugation and washing. Dry in a vacuum drying oven at 60℃ for 24 hours to obtain LDH@DNF.

[0123] Step S5: Prepare a Tris-HCl solution with pH=8.5. Add an appropriate amount of LDH@DNF to the Tris-HCl solution and sonicate for 10 minutes. Then add dopamine hydrochloride to a final concentration of 0.5 mg / mL and stir (500 rpm) at room temperature in the dark for 24 hours. Then wash the product by multiple centrifugations (1000 rpm, 10 min) to obtain a brown-black precipitate and freeze-dry it at -40℃ for 1-2 days to obtain PDA / LDH@DNF coated with a polydopamine outer membrane.

[0124] Example 14

[0125] This embodiment provides a method for preparing PDA / LDH@DNF, which differs from Example 13 in that: in step S5, the concentration of dopamine hydrochloride in the mixed solution is 1 mg / mL, and the other conditions are the same.

[0126] Example 15

[0127] This embodiment provides a method for preparing PDA / LDH@DNF, which differs from Example 13 in that: in step S5, the concentration of dopamine hydrochloride in the mixed solution is 1.5 mg / mL, and the other conditions are the same.

[0128] Example 16

[0129] This embodiment provides a method for preparing PDA / LDH@DNF, which differs from Example 13 in that: in step S5, the concentration of dopamine hydrochloride in the mixed solution is 2.0 mg / mL, and the other conditions are the same.

[0130] Example 17

[0131] This embodiment provides a method for preparing PDA / LDH@DNF, which differs from Example 13 in that: in step S5, the concentration of dopamine hydrochloride in the mixed solution is 2.5 mg / mL, and the other conditions are the same.

[0132] (iv) Zein / LDH@DNF coated with different zein proteins

[0133] Example 18

[0134] This embodiment provides a method for preparing Zein / LDH@DNF, specifically including the following steps:

[0135] Step S1: Prepare a mixed solution containing 0.04 mol / L MgCl2, 0.02 mol / L AlCl3, 0.0002 mol / L sodium dodecyl sulfate and 0.12 mol / L dinotefuran, denoted as solution A;

[0136] Step S2: Prepare a 0.12 mol / L NaOH solution, denoted as solution B.

[0137] Step S3: Prepare a NaCl solution with a concentration of 1 mol / L, denoted as solution C;

[0138] Step S4: Under the condition of N2 introduction, slowly add solution A and solution B dropwise into solution C, adjust the pH of the solution to 8.5-9, stir continuously, age for 2 hours, and then obtain a white precipitate by multiple centrifugation and washing. Dry in a vacuum drying oven at 60℃ for 24 hours to obtain LDH@DNF.

[0139] Step S5: Prepare an 85% ethanol aqueous solution containing 0.1% CTAB, add an appropriate amount of zein, and stir until completely dissolved. Then, take an appropriate amount of the LDH@DNF prepared above and disperse it in the solution, wherein the mass ratio of zein to LDH@DNF is 0.5:1. Stir at room temperature for 1 hour, then wash by multiple centrifugations (1000 rpm, 10 min) to obtain a light yellow precipitate and freeze-dry it to obtain Zein / LDH@DNF coated with a zein outer membrane.

[0140] Example 19

[0141] This embodiment provides a method for preparing Zein / LDH@DNF, which differs from Example 18 in that: in step S5, the mass ratio of zein to LDH@DNF is 1:1, and the remaining steps are the same.

[0142] Example 20

[0143] This embodiment provides a method for preparing Zein / LDH@DNF, which differs from Example 18 in that: in step S5, the mass ratio of zein to LDH@DNF is 1.5:1, and the remaining steps are the same.

[0144] Comparative Example 1

[0145] This comparative example provides an LDH material, which differs from Example 1 in that: fipronil was not added to solution C in step S1, while the other steps are the same.

[0146] Detection Example 1: Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy

[0147] First, Fourier transform infrared spectroscopy analysis was performed on the LDH@DNF prepared in Examples 1-10, the PDA / LDH@DNF prepared in Examples 13-17, and the Zein / LDH@DNF prepared in Examples 18-20, respectively.

[0148] The Fourier transform infrared spectra of LDH@DNF obtained in Examples 1-10 are as follows: Figure 1 As shown, DNF represents the fipronil pesticide group, and LDH represents the layered double hydroxide material group prepared using Comparative Example 1. The results show that the absorption peak of -OH and the peak at 1620 cm⁻¹ can be observed in the Fourier transform infrared spectra of LDH@DNF prepared in Examples 1-10. -1 and 1230cm -1 –NO2 absorption peak at 1420 cm⁻¹ -1 The CN absorption peak indicates that the present invention has successfully prepared a layered double hydroxide material (LDH@DNF) loaded with fipronil pesticide.

[0149] The Fourier transform infrared spectra of the PDA / LDH@DNF prepared in Examples 13-17 are as follows: Figure 2 As shown in the results, the detection results indicate that at 3400cm... -1 An absorption peak of the -OH group in the o-diphenol structure was detected at 1620 cm⁻¹. -1 An absorption peak of the aromatic ring was detected at 1500 cm⁻¹. -1 The detection of an imino-NH absorption peak indicates that the present invention has successfully prepared a layered double hydroxide material (PDA / LDH@DNF) loaded with dinotefuran pesticide and coated with a polydopamine outer membrane.

[0150] Fourier transform infrared spectra of Zein / LDH@DNF in Examples 18-20 are as follows: Figure 3 As shown in the results, the measurement depth is 3308cm. -1 An absorption peak of the NH group of the amide group -CO-NH- was detected at 1660 cm⁻¹. -1 An absorption peak for the C=O group of the amide group -CO-NH- was detected at the position.

[0151] Furthermore, the LDH, LDH@DNF, PDA / LDH@DNF, and Zein / LDH@DNF prepared in the embodiments of the present invention were observed by scanning electron microscopy, and the results are as follows. Figure 4 As shown.

[0152] The above results demonstrate that the corresponding DNF composite material based on layered double hydroxides was successfully prepared using the method of the present invention.

[0153] Example 2: Drug loading rate detection

[0154] This test example examines the drug loading rates of LDH@DNF prepared in Examples 1-10, PDA / LDH@DNF prepared in Examples 13-17, and Zein / LDH@DNF prepared in Examples 18-20. The specific testing methods are as follows:

[0155] The loading of fipronil was determined using UV-Vis spectrophotometry. 20 mg of LDH@DNF and PDA / LDH@DNF were added to 40 mL of HCl solution (pH = 1) and sonicated for 10 minutes until completely dissolved. A suitable amount of solution was then measured at 265 nm. The concentration of fipronil in the solution was calculated based on the standard curve. The loading content of the composite material was then calculated using the following formula:

[0156] LC(%)=V(C1-C0) / W×100%;

[0157] Where C0 (mg / L) represents the initial concentration of fipronil in the solution, C1 (mg / L) represents the concentration of fipronil in the solution after the reaction, V (mL) represents the total volume of the solution, and W (g) represents the mass of the composite material.

[0158] The drug loading determination process for Zein / LDH@DNF is as follows: 20 mg of Zein / LDH@DNF is added to 20 mL of aqueous solution containing 1 mg / mL protease, shaken for 10 minutes, 40 mL of HCl solution (pH=1) is added, and the solution is sonicated for 10 minutes to completely dissolve it. Then, an appropriate amount of solution is taken and its absorbance is measured at a wavelength of 265 nm. The drug loading is calculated using the above formula.

[0159] The drug loading rate test results of LDH@DNF prepared in Examples 1 to 10 are shown in Table 1.

[0160] Table 1: Drug loading rate detection results of LDH@DNF

[0161] Example 1 0.01 1.19±0.02 Example 2 0.02 2.76±0.12 Example 3 0.03 4.58±0.28 Example 4 0.04 5.31±0.69 Example 5 0.05 5.90±1.21 Example 6 0.06 6.70±0.32 Example 7 0.08 9.16±0.25 Example 8 0.10 12.24±0.49 Example 9 0.12 15.56±0.84 Example 10 0.14 14.53±0.62

[0162] As can be seen from the table, the highest drug loading rate of LDH@DNF was achieved when the concentration of dinotefuran (DNF) in solution A was 0.12 mol / L, with an average loading rate of 15.56%. However, when the DNF concentration was too high, the affinity of LDHs for dinotefuran reached saturation, and the excess DNF molecules blocked the pores of the MgAl-LDHs material, leading to a decrease in drug loading.

[0163] The drug loading rate test results of PDA / LDH@DNF prepared in Examples 13-17 are shown in Table 2.

[0164] Table 2: Drug loading rate test results of PDA / LDH@DNF

[0165] Example 13 0.5 4.92±0.02 Example 14 1.0 5.89±0.11 Example 15 1.5 8.03±0.10 Example 16 2.0 10.17±0.16 Example 17 2.5 9.11±0.25

[0166] As can be seen from the table above, after further treatment with different concentrations of dopamine hydrochloride, the drug loading rate of the prepared PDA / LDH@DNF decreased to varying degrees compared with the drug loading rate of LDH@DNF prepared in Example 9. This may be because the polydopamine polymerization reaction needs to be carried out in Tris-HCl solution (pH = 8.5), and DNF in LDH@DNF will be slowly released into the solution, resulting in the loss of the coating. Furthermore, as can be seen from the table, when the concentration of dopamine hydrochloride is 2.0 mg / mL, the decrease in drug loading rate is the lowest, still maintaining a drug loading rate of 10.17%.

[0167] The drug loading rate of Zein / LDH@DNF prepared in Examples 18-20 is shown in Table 3.

[0168] Table 3: Results of drug loading rate detection for Zein / LDH@DNF

[0169] Example 18 0.5 8.56±0.11 Example 19 1.0 11.85±0.49 Example 20 1.5 12.07±0.32

[0170] As can be seen from the table above, when zein was further treated, the decrease in drug loading rate was less than that after dopamine hydrochloride treatment, and when the mass ratio of zein to LDH@DNF was 1.5:1, the drug loading rate remained at 12.07%.

[0171] Test Example 3: Environmental Response Release Performance Test

[0172] 1. pH-responsive release performance

[0173] This test example examines whether the PDA / LDH@DNF prepared in Example 16 has pH-responsive release performance. Specifically, the PDA / LDH@DNF prepared in Example 16 was placed in solutions with different pH values ​​(5, 7, and 9) for treatment, and the diffusion of DNF to the outside world was detected during the process.

[0174] The results showed that under weakly acidic conditions (pH=5), the cumulative release of PDA / LDH@DNF reached 73.65% within 1 hour. This burst release phenomenon was attributed to the rapid dissolution of the outer layer of PDA under weakly acidic conditions, causing some of the DNF loaded on the MgAl-LDHs surface to diffuse rapidly into the external solution environment driven by the concentration gradient. In the same timeframe, the cumulative release of PDA / LDH@DNF under neutral (pH=7) and weakly alkaline (pH=9) conditions was only 46.75% and 18.33%, respectively. The burst release phenomenon was less pronounced under weakly acidic conditions because the dissolution of PDA under neutral and weakly alkaline conditions was slower than under weakly acidic conditions, thus reducing the diffusion rate of DNF to the outside environment. The release of PDA / LDH@DNF reached equilibrium around 4 hours, at which point the cumulative release under weakly acidic conditions reached 84.86%, while at pH 7 and 9, the cumulative release of DNF ultimately reached only 59.59% and 33.44%, respectively.

[0175] Therefore, it can be seen that the PDA / LDH@DNF sustained-release system prepared in this invention exhibits pH sensitivity under different pH conditions.

[0176] 2. Enzyme response release performance

[0177] This test example examined the release performance of Zein / LDH@DNF prepared in Example 19 in response to the enzyme. The specific method was as follows: 0.1 g of Zein / LDH@DNF was added to 300 mL of aqueous solution, and 0.1 g of papain was added. The solution was shaken at room temperature for 2 hours. At regular intervals, 1 mL of sample was taken and the same volume of solution was added. The content of fipronil in the sample was determined using a UV-Vis spectrophotometer (265 nm), and the cumulative release rate was calculated.

[0178] The formula for cumulative release rate is as follows:

[0179]

[0180] Among them, C t (mg / L) and V t (L) represents the concentration of fipronil and the volume of solution taken at time t, V0(L) represents the total volume of solution, and m0(g) represents the total mass of fipronil.

[0181] The results showed that when the drug-loaded formulation is ingested by insects and enters their bodies, it rapidly disintegrates within the insects due to the hydrolytic action of proteases, achieving an enzyme-responsive release effect. In this test case, when protease was added to the release medium, Zein / LDH@DNF exhibited a faster release, with a cumulative release rate reaching 37.52% at 30 minutes, significantly higher than the 15.98% cumulative release rate without protease in the same timeframe. After 2 hours of release experiments, the release of Zein / LDH@DNF gradually reached equilibrium, at which point the cumulative release rate with protease reached 46.77%, while in the absence of protease, the cumulative release rate of Zein / LDH@DNF after 2 hours was approximately 24.69%.

[0182] Therefore, the Zein / LDH@DNF sustained-release system prepared by this invention exhibits enzyme-responsive release performance. In the presence of protease, Zein / LDH@DNF shows a faster release, while in the absence of protease, its cumulative release amount decreases significantly.

[0183] Test Example 4: Resistance to Photolysis Test

[0184] This test example examines the photodegradation rate of LDH@DNF (Example 8), PDA / LDH@DNF (Example 16), and Zein / LDH@DNF (Example 19) prepared according to this invention, as well as DNF technical material (Hurui 20% fipronil soluble granules, purchased from Mitsui Chemicals ARGO Co., Ltd., Japan) and commercially available DNF formulations. The specific test methods are as follows:

[0185] A certain amount of DNF technical, commercially available DNF formulation, LDH@DNF, PDA / LDH@DNF, and Zein / LDH@DNF were added to 100 mL of water to prepare a mixed solution with an equivalent concentration of 10 mg / L of fipronil. The solution was placed under a UV lamp (wavelength 254 nm) to ensure sufficient irradiation. The residual concentration of fipronil in the solution was measured at regular intervals, and the degradation rate of fipronil was calculated using the following formula:

[0186] D% = V(C0-C1) / W × 100%;

[0187] Where C0 (mg / L) represents the initial concentration of fipronil in the solution, C1 (mg / L) represents the concentration of fipronil in the solution after the reaction, V (mL) represents the total volume of the solution, and W (g) represents the total mass of fipronil.

[0188] The test results are shown in Table 4 and Figure 5 As shown.

[0189] Table 4: Photodegradation rate (%) of various pesticide formulations

[0190]

[0191] The results showed that under ultraviolet light irradiation, the DNF technical material underwent rapid photodegradation, with a degradation rate of 83.46% after 120 minutes of irradiation. The photodegradation rate of commercially available DNF formulations also reached 67.82%. The three drug-loaded systems, LDH@DNF, PDA / LDH@DNF, and Zein / LDH@DNF, all exhibited good resistance to photodegradation, with degradation rates of 42.46%, 32.93%, and 46.11% under ultraviolet light irradiation, respectively. This is because DNF is located in the interlayer structure of LDHs, which slows down the rate of degradation of DNF under light irradiation. In addition, PDA / LDH@DNF showed significantly better resistance to photodegradation than LDH@DNF and Zein / LDH@DNF. This result indicates that the addition of PDA can further alleviate the photodegradation of DNF. This may be because PDA is brownish-black and coats the outer surface of LDH@DNF. Firstly, it can prevent ultraviolet light from directly contacting DNF molecules. Secondly, it can absorb ultraviolet light and convert it into heat that is harmless to the drug, thus slowing down photodegradation, improving the stability of DNF to ultraviolet light, and prolonging the duration of DNF's effect.

[0192] Test Example 5: Long-lasting insecticidal effect test

[0193] This test example examines the long-lasting insecticidal effects of the LDH@DNF (Example 8), PDA / LDH@DNF (Example 16), and Zein / LDH@DNF (Example 19) prepared according to the present invention, as well as the LDH material, DNF technical (Hurui 20% fipronil soluble granules, purchased from Mitsui Chemicals ARGO Co., Ltd., Japan), and commercially available DNF formulations prepared in Comparative Example 1. The specific test methods are as follows:

[0194] The fall armyworm (Spodoptera frugiperda) was selected as the experimental insect for insecticide efficacy experiments. Seven experimental groups were set up: blank control group, LDH group, DNF technical group, commercially available DNF formulation group, LDH@DNF group, PDA / LDH@DNF group, and Zein / LDH@DNF group. Eight healthy and active fall armyworm larvae of uniform growth were used in each group, with 5g of feed added and DNF added at a rate of 5mg / g of feed. The dosage of different materials was calculated based on the drug loading of commercially available DNF formulation, LDH@DNF, PDA / LDH@DNF, and Zein / LDH@DNF (as shown in Table 5). Each experimental group included three replicates. The experiment lasted for 24 hours, and the health status of the fall armyworm larvae was observed and recorded every 6 hours.

[0195] Table 5: Pesticide Formulation Dosage

[0196] LDH 135.7 0 DNF original medicine 25.0 25.00 Commercially available DNF preparations 125.0 25.00 LDH@DNF 160.7 25.00 PDA / LDH@DNF 245.8 25.00 Zein / LDH@DNF 211.0 25.00

[0197] The test results are shown in Table 6 and Figure 6 As shown.

[0198] Table 6: Insecticide efficacy (%) of various pesticide formulations

[0199]

[0200] The results showed that the insecticidal toxicity of DNF technical and commercially available DNF formulation was the fastest-acting. After adding DNF technical and commercially available DNF formulation to the feed, fall armyworm larvae exhibited extreme excitement and continuous wriggling and twisting within 2 hours, indicating that DNF had been rapidly absorbed into the larvae's bodies. This DNF inhibited the acetylcholinesterase receptors of the pests, causing severe disorders in the central nervous system, which further led to the death of the pests due to extreme nerve excitation. At 6 hours, the mortality rates of the pests in the DNF technical and commercially available DNF formulation experimental groups were 81.25% and 68.75%, respectively. Within 12 hours, the mortality rate of the pests in the DNF technical and commercially available DNF formulation experimental groups reached 100%, with all fall armyworm larvae dying. LDH@DNF showed slightly slower insecticidal efficacy against fall armyworm larvae than DNF technical and commercially available DNF formulations. The mortality rate was 43.75% at 6 hours and reached 87.5% within 12 hours, indicating a slightly lower efficacy than DNF technical and commercially available DNF formulations. This suggests that LDH@DNF exhibits slow-release properties compared to DNF technical and commercially available DNF formulations. PDA / LDH@DNF and Zein / LDH@DNF also had a slower onset of action, with mortality rates of 18.75% and 31.25% respectively at 6 hours, 75% and 81.25% at 18 hours, and reaching 100% after 24 hours. The slower insecticidal efficacy of PDA / LDH@DNF and Zein / LDH@DNF compared to DNF technical, commercially available DNF formulations, and LDH@DNF is mainly due to their slow-release effects. Furthermore, in the early stage of the experiment (within 6 hours), the insecticidal rate of Zein / LDH@DNF (31.25%) was slightly higher than that of PDA / LDH@DNF (18.75%). This may be because after the fall armyworm larvae ingested the feed containing Zein / LDH@DNF drug-loaded particles, the protease inside the pest promoted the release of DNF from the Zein / LDH@DNF drug-loaded system. Therefore, the insecticidal efficiency of the Zein / LDH@DNF experimental group was faster than that of the PDA / LDH@DNF experimental group.

[0201] The above results demonstrate that the LDH@DNF, PDA / LDH@DNF, and Zein / LDH@DNF sustained-release drug delivery systems prepared in this invention all have a slow release effect while ensuring the insecticidal efficacy of DNF.

[0202] Test Example 6: Test on the slow-release effect of pesticides

[0203] This test example measures the concentration of DNF in the leachate of LDH@DNF (Example 8), PDA / LDH@DNF (Example 16), and Zein / LDH@DNF (Example 19) prepared according to the present invention, as well as in the leachate of DNF technical material (Hurui 20% fipronil soluble granules, purchased from Mitsui Chemicals ARGO Co., Ltd., Japan) and commercially available DNF formulations. The specific test methods are as follows:

[0204] 70g of soil was used to fill a polyvinyl chloride column (38mm inner diameter × 100mm height) with air-dried red soil topsoil (1-20cm) that had passed through a 2mm sieve. The bottom layer consisted of three layers of 0.15mm nylon mesh, 30g of coarse silica sand (6-8 mesh), and 15g of fine silica sand (70-110 mesh). 50ml of pure water was then added to balance the soil column. 1.5g of soil was then mixed with equal amounts of DNF technical grade, commercially available DNF formulation, LDH@DNF, PDA / LDH@DNF, and Zein / LDH@DNF (all containing 7mg DNF, i.e., a concentration of 100mg DNF / kg soil) and dispersed on the soil surface for 24 hours to equilibrate. The solution was then slowly leached using a peristaltic pump, with a total of 120mL of water added. The concentration of dinotefuran in the leachate was measured. The dosage of each pesticide formulation is shown in Table 7.

[0205] Table 7: Pesticide Formulation Dosage

[0206]

[0207]

[0208] The statistical data of DNF concentration in the leachate of different drug-loaded systems are shown in Table 8 and Figure 7 As shown.

[0209] Table 8: DNF Concentration in Leachate from Different Drug Loading Systems

[0210]

[0211]

[0212] The leaching rates of different drug loading systems are shown in Table 9 and... Figure 8 As shown.

[0213] Table 9: Leaching rates of different drug loading systems

[0214]

[0215]

[0216] The results showed that for both the DNF technical and commercially available DNF formulations, the leaching rates reached 59.92% and 79.91% respectively after leaching 40 mL; after leaching 60 mL, DNF was nearly completely leached, with leaching rates of 92.45% and 96.23% respectively; ultimately, both the DNF technical and commercially available DNF formulations achieved 100% complete leaching, which can be attributed to the high solubility of DNF and its extremely high risk of leaching loss. For the LDH@DNF formulation, the leaching rate was 60.09% after leaching 40 mL, and stabilized at 74.53% after leaching 60 mL, with a final leaching rate of 78.73%. Compared to the final leaching rates of the DNF technical and commercially available DNF formulations, the leaching rate of the LDH@DNF loading system was lower, with approximately 10% of the DNF not being lost through leaching. The leaching rates of PDA / LDH@DNF and Zein / LDH@DNF were the lowest, at 35.69% and 30.86% respectively after leaching 40 mL. After leaching 60 mL, the leaching rates were close to the leaching equilibrium, with values ​​of 42.68% and 34.68% respectively. The final leaching rates of PDA / LDH@DNF and Zein / LDH@DNF were only 45.45% and 35.28% respectively. More than half of the DNF in the drug-loaded system was not leached out due to leaching and remained in the drug-loaded system, and the leaching loss was significantly alleviated.

[0217] The above results demonstrate that the layered double hydroxide-type drug-loaded particles prepared in this invention can significantly reduce the leaching risk of DNF in soil and reduce the residue of DNF in the soil environment.

[0218] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A controlled-release formulation of a biopesticide based on layered double hydroxides, characterized in that, It comprises a core consisting of a layered double hydroxide material and a biopesticide loaded on the surface and internal pores of the layered double hydroxide material, and a zein shell covering the surface of the core; The preparation method of the controlled-release biological pesticide formulation includes the following steps: Step S1: Prepare a mixed solution A containing divalent metal salt, trivalent metal salt, anionic surfactant and the biological pesticide; Step S2: Under an inert atmosphere, mix the mixed solution A, the alkaline solution and the metal salt solution, adjust the pH value to 8.5-9, react, separate the solid and liquid, collect the precipitate and dry it; Step S3: Mix the dried material with an alcohol solvent containing hexadecyltrimethylammonium bromide and zein to obtain a complex II solution. React, separate the solid and liquid phases, collect the solid phase, and obtain the product. The biological pesticide is fipronil, and the concentration of fipronil in the mixed solution A is 0.08~0.14 mol / L; the mass ratio of zein to the dried material in the complex II solution is 0.5~1.5:

1.

2. The controlled-release formulation of biological pesticide according to claim 1, characterized in that, The loading rate of the biopesticide is 1-20%.

3. A method for preparing a controlled-release formulation of a biological pesticide as described in claim 1 or 2, characterized in that, Includes the following steps: Step S1: Prepare a mixed solution A containing divalent metal salt, trivalent metal salt, anionic surfactant and the biological pesticide; Step S2: Under an inert atmosphere, mix the mixed solution A, the alkaline solution and the metal salt solution, adjust the pH value to 8.5-9, react, separate the solid and liquid, collect the precipitate and dry it; Step S3: Mix the dried material with an alcohol solvent containing hexadecyltrimethylammonium bromide and zein to obtain a complex II solution. React, separate the solid and liquid phases, collect the solid phase, and obtain the product. The biological pesticide is fipronil, and the concentration of fipronil in the mixed solution A is 0.08~0.14 mol / L; the mass ratio of zein to the dried material in the complex II solution is 0.5~1.5:

1.

4. The preparation method according to claim 3, characterized in that, The divalent metal salt includes at least one of divalent magnesium salt, divalent nickel salt, divalent copper salt, divalent calcium salt, and divalent zinc salt; And / or, the trivalent metal salt includes at least one of trivalent aluminum salt, trivalent chromium salt, and trivalent iron salt; And / or, the anionic surfactant includes at least one of sodium carboxymethyl cellulose, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and calcium dodecylbenzene sulfonate.

5. The preparation method according to claim 4, characterized in that, The concentration of divalent and / or trivalent metal salts in the mixed solution A is 0.01~0.08 mol / L; And / or, the concentration of the anionic surfactant in the mixed solution A is 0.0001~0.0004 mol / L.

6. The application of the controlled-release biological pesticide formulation based on layered double hydroxides as described in claim 1 or 2, or the controlled-release biological pesticide formulation prepared by the preparation method as described in any one of claims 3 to 5, in the preparation of pesticides.

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