Preparation method and application of metal organic framework nano pesticide controlled release agent

Abstract

The present invention belongs to the field of pesticide preparation, and particularly relates to a preparation method and application of a metal organic framework nano pesticide controlled release agent, comprising the following steps: dispersing a nano-sized MOF material with relatively large mesopores in an organic solvent, adding a pesticide active ingredient, loading the pesticide active ingredient into the pores of the MOF nano material, centrifuging to obtain a drug-loaded MOF nano material; dispersing the obtained product in an aqueous solution containing lignin sulfonate, stirring, centrifuging to obtain a lignin sulfonate-encapsulated MOF nano pesticide controlled release agent; dispersing the obtained product in an aqueous solution containing chitosan, stirring, centrifuging, separating, washing, and drying to obtain a target product, a lignin sulfonate and chitosan double-encapsulated MOF nano pesticide controlled release agent. The present invention has the characteristics of being suitable for large-sized pesticide molecules, simple preparation, low cost, high pesticide loading, and resistance to pesticide ultraviolet light degradation.

Description

Technical Field

[0001] The invention belongs to the field of pesticide preparations, and particularly relates to a preparation method and application of a metal organic framework nano pesticide controlled-release agent. Background Art

[0002] Food security and food safety are the basic guarantees for human survival and healthy life. Only by continuously increasing the crop yield of the existing cultivated land area can the growing demand for food and agricultural products of the global population be met. As long as there are crops, there will be harmful organisms (such as pathogens and pests), and pesticides need to be used for prevention and control. The use of pesticides plays an irreplaceable role in increasing the yield of crops and agricultural products. However, due to the drift of pesticide spray droplets, the rolling of pesticide liquid on crop leaves, rain erosion, ultraviolet photolysis, etc., the actual utilization rate of target organisms for traditional pesticide formulations is less than 0.1%. In order to cope with the extremely low pesticide utilization rate, excessive pesticides must be used to control pests and diseases, which inevitably leads to ecological environmental pollution, pesticide residues in agricultural products, and ultimately poses a serious threat to human public health. Pesticide off-target loss is a key problem of the extremely low efficiency of traditional pesticide formulations. In order to reduce the amount of pesticides used and improve the efficacy of pesticides, water-based nanopesticide controlled-release agents with small size and high specific surface area are expected to solve the key problems of traditional pesticide formulations. Nanopesticides are pesticide formulations that use nanomaterials and preparation technology to effectively and efficiently combine the original drug, carrier and adjuvant. In 2019, the International Union of Pure and Applied Chemistry (IUPAC) released the top ten emerging chemical technologies that changed the world for the first time, and nanopesticides ranked first. Water-based nanopesticide formulations can significantly improve the apparent dispersion of pesticides in water, increase the deposition and retention of pesticides on crop leaves, achieve controlled release of pesticides, improve the bioavailability of pesticides, and reduce the amount of pesticides used.

[0003] In recent years, nanopesticides based on metal organic frameworks (MOFs) have attracted great attention. MOFs are porous crystalline materials formed by coordination between metal ions / metal oxygen clusters and various organic ligands. At present, research on MOF nanopesticides is mainly based on two widely used MOF materials (e.g., ZIF-8 and UiO-66). ZIF-8 (composed of Zn 2+ and 2-methylimidazole) has a cage of 1.16 nm connected by a small window of 0.34 nm. Due to the small window aperture of ZIF-8, pesticide molecules cannot be loaded into the synthesized ZIF-8 material. Pesticide molecules can only be intercalated into the ZIF-8 material in the presence of pesticide active ingredients through the one-pot preparation of ZIF-8. IVOxygen clusters and terephthalic acid coordinated) have 1.1 nm octahedral cages and 0.8 nm tetrahedral cages, the ratio of the two is 1:2, connected by 0.6 nm triangular windows. The small size of the cage and triangular window makes it difficult to load pesticide molecules into the smaller micropores of UiO-66, and the pesticide molecules are mainly adsorbed on the surface of the UiO-66 material. These research systems do not fully utilize the pore structure of MOF materials. In addition, it is difficult to use similar MOF materials such as ZIF-8 and UiO-66 to prepare smart controlled-release nanopesticides. By selecting suitable MOF materials with large micropores (<2 nm) or mesopores (2-50 nm) size, good biocompatibility, high thermal, mechanical and chemical stability, these MOF nanomaterials can load pesticide molecules in large micropores or mesopores, and then encapsulate their surfaces to prepare MOF nanopesticide controlled-release agents.

[0004] Abamectin (AVM) is a biological pesticide produced by fermentation of Streptomyces griseus in Streptomyces. It stimulates the release of γ-aminobutyric acid, which has an inhibitory effect on arthropod nerve conduction, interferes with neurophysiological activities, paralyzes and kills pests. However, avermectin with a 16-membered macrolide structure has disadvantages such as poor water solubility and easy ultraviolet degradation, which affects the insecticidal effect of avermectin. Emamectin benzoate (emamectin benzoate) is a new type of highly effective semi-synthetic antibiotic insecticide synthesized from avermectin, and its mechanism of action is basically the same as that of avermectin. Emamectin benzoate has the characteristics of ultra-high efficiency, low toxicity, low residue, and pollution-free biological pesticides. It has been widely used in the prevention and control of various pests on crops such as vegetables, fruit trees, tobacco, tea, cotton, and soybeans. Compared with avermectin, the insecticidal activity is increased by 3 orders of magnitude, and it does not harm beneficial insects in the process of pest control. However, emamectin benzoate still has the disadvantages of poor water solubility and easy ultraviolet degradation. High-efficiency cypermethrin is a broad-spectrum insecticide that is non-systemic but has contact and stomach poisoning effects. It interacts with the sodium channels of pests to destroy their nervous system functions. Since avermectin and emamectin benzoate are biological pesticides, the insecticidal process is slow. For crops that have already suffered a large number of insect pests, avermectin or emamectin benzoate is used in combination with high-efficiency cypermethrin. It has good rapid effect, a wider spectrum of insecticidal effects, low price, and a long lasting effect. Pyraclostrobin is a broad-spectrum fungicide that inhibits mitochondrial respiration and ultimately causes cell death. It has protective, therapeutic, penetrating, systemic conductivity and rainwater erosion resistance. It has a long lasting effect and a wide range of applications. In addition to having a direct effect on pathogens, pyraclostrobin can also increase the absorption of nitrogen by crops, thereby promoting rapid growth of crops and increasing crop yields, thereby achieving the goal of high crop yields. However, if pyraclostrobin is used in excessive amounts, it will lead to excessive growth and late maturity of crops. It is worth pointing out that avermectin, emamectin benzoate, cypermethrin and pyraclostrobin all have relatively large molecular sizes. Only MOF nanocarriers with larger mesoporous structures can effectively load them into the pores to prepare nanoformulations. This also brings about the problems of encapsulation on the surface of larger mesoporous MOFs and premature leakage of pesticides. Summary of the invention

[0005] The present invention aims to overcome the shortcomings of the prior art and provide a method for preparing a metal organic framework nano pesticide controlled-release agent which is particularly suitable for large-sized pesticide molecules, has simple preparation, low cost, high pesticide loading, resists pesticide ultraviolet light degradation, and can promote pesticide reduction and efficiency enhancement, and its application.

[0006] To solve the above technical problems, the present invention is achieved as follows:

[0007] A method for preparing a metal organic framework nano pesticide controlled release agent comprises the following steps:

[0008] Step 1: Dispersing the metal organic framework nanomaterial in an organic solvent A, adding the pesticide active ingredient, stirring at room temperature, loading the pesticide active ingredient into the pores of the metal organic framework nanomaterial, and centrifuging to obtain the drug-loaded metal organic framework nanomaterial;

[0009] Step 2: dispersing the drug-loaded metal organic framework nanomaterial obtained in step 1 in an aqueous solution containing lignin sulfonate, stirring at room temperature, and centrifuging to obtain a lignin sulfonate-encapsulated metal organic framework nanopesticide controlled-release agent;

[0010] Step 3: Disperse the lignin sulfonate encapsulated metal organic framework nanopesticide obtained in step 2 in an aqueous solution containing chitosan, stir at room temperature, centrifuge, separate, wash and dry to obtain the target product, lignin sulfonate and chitosan double encapsulated metal organic framework nanopesticide controlled release agent.

[0011] Furthermore, the metal organic framework nanomaterial in step 1 is PCN-777 nanoparticles or NU-1000 nanoparticles.

[0012] Furthermore, the method for preparing the PCN-777 nanoparticles comprises the following steps: 2 8H 2 O and organic ligand 2,4,6-tris(4′-carboxyphenyl)-1,3,5-triazine are dissolved in organic solvent B in a molar ratio of 10 to 2:1, 10 to 55 molar equivalents of trifluoroacetic acid of the organic ligand are added, mixed evenly, placed in a reaction kettle, reacted at 110 to 160° C. for 5 to 24 h, cooled to room temperature, centrifuged, washed with organic solvent B and organic solvent A, respectively, and dried to obtain PCN-777 nanoparticles.

[0013] Furthermore, the method for preparing the NU-1000 nanoparticles comprises the following steps: 4 and an organic ligand 1,3,6,8-tetrakis(4′-carboxyphenyl)pyrene are dissolved in an organic solvent B at a molar ratio of 20 to 5:1, 1000 to 4000 molar equivalents of acetic acid of the organic ligand are added, and water is added at a volume ratio of acetic acid to water of 5:0 to 3, mixed evenly, placed in a reaction kettle, reacted at 70 to 120° C. for 0.3 to 3 h, cooled to room temperature, centrifuged, solvent exchanged with organic solvent B and organic solvent A respectively, and dried to obtain NU-1000 nanoparticles.

[0014] Furthermore, the organic solvent A is at least one of ethanol and acetone.

[0015] Furthermore, the organic solvent B is at least one of dimethylformamide or diethylformamide.

[0016] Furthermore, the active ingredient of the pesticide is one of avermectin, avermectin benzoate, high-efficiency cypermethrin, and pyraclostrobin, or a mixture of two or more thereof.

[0017] Furthermore, the mass ratio of the metal organic framework nanomaterial to the pesticide active ingredient in step 1 is 1:0.5-10; and the concentration of the pesticide active ingredient in the organic solvent A is 4-100 g / L.

[0018] Furthermore, the lignin sulfonate is at least one of sodium lignin sulfonate or calcium lignin sulfonate; the mass ratio of the lignin sulfonate to chitosan is 1:0-5; the mass ratio of the metal organic framework nanomaterial to the lignin sulfonate is 1:0.2-5.

[0019] The product obtained by the preparation method of the above metal organic framework nano pesticide controlled release agent is used in pesticide control to control the release of pesticides through environmental factors; the environmental factors are one or a combination of two or more of pH value, laccase, phosphate, and phytic acid.

[0020] The present invention discloses a preparation method and pesticide controlled release method of a MOF nanopesticide controlled release agent which is particularly suitable for large-sized pesticide molecules, has simple preparation, low cost, high pesticide loading, and resistance to pesticide ultraviolet degradation. Highly stable zeolite-type mesoporous PCN-777 (composed of Zr IV Oxygen clusters and 2,4,6-tris(4′-carboxyphenyl)-1,3,5-triazine) have a large mesoporous cage of 3.5 nm, and NU-1000 (composed of Zr IV Oxygen clusters and 1,3,6,8-tetrakis(4′-carboxyphenyl)pyrene) have larger mesoporous cages of 3 nm. These MOF materials with larger mesopores can load larger pesticide molecules, prepare nanopesticide controlled release agents, prevent pesticide UV degradation, improve the control effect on target organisms, and reduce toxicity to non-target organisms. So far, there are no reports on PCN-777 materials as drug or pesticide nanocarriers, nor on NU-1000 materials as pesticide nanocarriers. Lignin is a natural polymer and one of the components of plant cell walls. Its content is second only to cellulose and chitin. There are active groups such as aromatic groups, phenolic hydroxyl groups, alcoholic hydroxyl groups, carbonyl groups, and conjugated double bonds in the molecular structure of lignin. Most of the applications of lignin are in the form of lignin sulfonates. Sodium lignin sulfonate and calcium lignin sulfonate are non-toxic, soluble in water, have strong dispersibility, low cost, and are environmentally friendly. Through strong coordination (MOF surface coordination unsaturated Zr IVLignosulfonate is encapsulated on the surface of drug-loaded PCN-777 or NU-1000 nanoparticles through electrostatic interaction (MOF surface positive charge and lignin sulfonate anion), thereby preparing lignin sulfonate-encapsulated MOF nanopesticide controlled-release agent. Further, through the electrostatic interaction and hydrogen bonding between chitosan and lignin sulfonate, chitosan is encapsulated on the surface of drug-loaded MOF nanoparticles encapsulated by lignin sulfonate, thereby preparing MOF nanopesticide controlled-release agent double-encapsulated by lignin sulfonate and chitosan. Double encapsulation can obtain better pesticide encapsulation performance and prevent pesticide leakage in advance. The organic ligands and lignin sulfonates of MOF nanomaterials have obvious absorption of ultraviolet light and can resist the ultraviolet degradation of pesticides loaded in the MOF pores. According to the characteristics of pests and diseases, the properties of lignin sulfonate, the properties of MOF materials, and the physiological environment of crops, the present invention discloses several stimulus-responsive pesticide controlled release methods: pH (crops, pathogens, pests), laccase (polyphenol oxidase; plant cell walls, pathogens, pests), phosphate (plants), phytic acid (inositol hexaphosphate; plants). The preparation method of the MOF nanopesticide controlled release agent of the present invention is particularly suitable for large-sized pesticide molecules (including drug molecules smaller than the mesoporous channels), and has the advantages of simple preparation, low cost, high pesticide loading, and resistance to pesticide ultraviolet degradation, which promotes the reduction of pesticide application and increases its efficiency, and solves the key problems faced by traditional pesticide preparations.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. PCN-777 has a larger mesoporous cage of 3.5 nm, and NU-1000 has a larger mesoporous cage of 3 nm. The preparation of these MOF nanomaterials with larger mesopores is particularly suitable for loading larger pesticide molecules (avermectin, emamectin benzoate, high-efficiency cypermethrin, pyraclostrobin, etc.), preparing MOF nanopesticide controlled-release agents, improving the control effect on target organisms, reducing toxicity to non-target organisms, and achieving the purpose of reducing pesticides and increasing their efficiency.

[0023] 2. The phenolic hydroxyl groups of lignin sulfonate coordinate with the unsaturated Zr on the MOF surface IVThe strong multiple coordination between the sites, the electrostatic interaction between the sulfonate ions of lignin sulfonate and the positively charged MOF surface, etc., make the lignin sulfonate firmly encapsulated on the surface of drug-loaded PCN-777 or NU-1000 nanoparticles, and the prepared lignin sulfonate encapsulated MOF nanopesticide controlled release agent can achieve the purpose of pesticide controlled release. Furthermore, a MOF nanopesticide controlled release agent with dual encapsulation of lignin sulfonate and chitosan was prepared, which can obtain better pesticide encapsulation performance, prevent pesticides from leaking prematurely, and meet the purpose of pesticide controlled release. Both lignin sulfonate and chitosan are polymers derived from nature, which are non-toxic, low-cost and environmentally friendly.

[0024] 3. The pesticide loading in the MOF nanopesticide controlled-release agent doubly encapsulated by lignin sulfonate and chitosan is 25% (mass percentage). The high pesticide loading enables low-concentration MOF nanopesticide controlled-release formulations to achieve the effect of preventing and controlling pests and diseases, reducing the production cost of users and the difficulty of formulation and spraying.

[0025] 4. The organic ligands and lignin sulfonates of MOF nanomaterials have obvious absorption of ultraviolet light, which can resist the ultraviolet light degradation of pesticides loaded in the MOF pores and improve the effective utilization rate of pesticides.

[0026] 5. According to the characteristics of pests and diseases, the properties of lignin sulfonates, the properties of MOF materials, and the physiological environment of crops, the present invention discloses several stimulus-responsive pesticide controlled release methods: pH (acidic, alkaline), laccase, phosphate, and phytic acid, to achieve the pesticide controlled release use of MOF nanopesticide controlled-release agents, improve the prevention and control effect on target organisms, and reduce toxicity to non-target organisms.

[0027] 6. The preparation method of the MOF nanopesticide controlled-release agent of the present invention is particularly suitable for large-sized pesticide molecules and has the advantages of simple preparation, low cost, high pesticide loading, and resistance to pesticide ultraviolet light degradation. It promotes the reduction of pesticide application and increases its efficiency, and solves the key problems faced by traditional pesticide preparations. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 To prepare the organic ligand 2,4,6-tris(4′-carboxyphenyl)-1,3,5-triazine (H 3 Chemical structure of TATB).

[0029] Figure 2 Scanning electron microscope (SEM) photos of the PCN-777 nanoparticles (a) prepared in Example 1 and the avermectin PCN-777 nanopesticide controlled-release agent (b) double-encapsulated by sodium lignin sulfonate and chitosan prepared in Example 4.

[0030] Figure 3 The X-ray diffraction (XRD) diagrams are of the PCN-777 nanoparticles prepared in Example 1, the PCN-777 nanoparticles loaded with avermectin prepared in Example 3, and the avermectin PCN-777 nanopesticide controlled-release agent double-encapsulated with sodium lignin sulfonate and chitosan prepared in Example 4.

[0031] Figure 4 The dynamic light scattering (DLS) particle size distribution diagram of the PCN-777 nanoparticles prepared in Example 1 and the avermectin PCN-777 nanopesticide controlled-release agent double-encapsulated by sodium lignin sulfonate and chitosan prepared in Example 4.

[0032] Figure 5 The zeta potential (zeta) diagrams are of the PCN-777 nanoparticles prepared in Example 1, the PCN-777 nanoparticles loaded with avermectin prepared in Example 3, the sodium lignin sulfonate encapsulated avermectin PCN-777 nanopesticide controlled-release agent prepared in Example 3, and the sodium lignin sulfonate and chitosan double encapsulated avermectin PCN-777 nanopesticide controlled-release agent prepared in Example 4.

[0033] Figure 6 The nitrogen adsorption-desorption isotherms (a) and the corresponding pore size distribution (b) of the PCN-777 nanoparticles prepared in Example 1, the PCN-777 nanoparticles loaded with avermectin prepared in Example 3, and the avermectin PCN-777 nanopesticide controlled-release agent double-encapsulated with sodium lignin sulfonate and chitosan prepared in Example 4.

[0034] Figure 7 The thermogravimetric analysis (GTA) curves of the PCN-777 nanoparticles prepared in Example 1, the PCN-777 nanoparticles loaded with avermectin prepared in Example 3, and the avermectin PCN-777 nanopesticide controlled-release agent double-encapsulated with sodium lignin sulfonate and chitosan prepared in Example 4.

[0035] Figure 8 Sodium lignin sulfonate, chitosan, avermectin original drug, organic ligand (H 3 TATB), PCN-777 nanoparticles prepared in Example 1, and the UV-visible absorption spectra of the avermectin PCN-777 nanopesticide controlled-release agent double-encapsulated by sodium lignin sulfonate and chitosan prepared in Example 4.

[0036] Fig. 9 The UV degradation curve of the active ingredient of avermectin in the avermectin original drug and the avermectin PCN-777 nano pesticide controlled-release agent double-encapsulated with sodium lignin sulfonate and chitosan prepared in Example 4 (Example 9).

[0037] Fig.10 a~d are respectively the pesticide controlled release curves of the avermectin PCN-777 nano pesticide controlled release agent double-encapsulated by sodium lignin sulfonate and chitosan prepared in Example 4 in response to pH value (acidic, alkaline), laccase, phosphate, and phytic acid (PA) stimulation (Example 10).

[0038] Fig.11 Chemical structure of 1,3,6,8-tetrakis(4′-carboxyphenyl)pyrene, an organic ligand used to prepare NU-1000.

[0039] Fig.12 This is a scanning electron microscope (SEM) photograph of the NU-1000 nanoparticles prepared in Example 2.

[0040] Fig.13 This is the X-ray diffraction (XRD) pattern of the NU-1000 nanoparticles prepared in Example 2.

[0041] Fig.14 This is the zeta potential (zeta) diagram of the NU-1000 nanoparticles prepared in Example 2.

[0042] Fig.15 The nitrogen adsorption-desorption isotherm curve (a) and the corresponding pore size distribution (b) of the NU-1000 nanoparticles prepared in Example 2. DETAILED DESCRIPTION

[0043] In order to make those skilled in the art better understand the technical solution of the present invention, the present invention is further described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. These embodiments should be understood to be only used to illustrate the present invention and not to limit the protection scope of the present invention. After reading the contents recorded in the present invention, all other embodiments obtained after various changes or modifications made to the present invention based on the technical solution and embodiments of the present invention also fall within the scope of protection of the claims of the present invention.

[0044] Example 1: Preparation of PCN-777 Nanoparticles

[0045] ZrOCl 2 8H 2O (360 mg) and organic ligand 2,4,6-tris(4′-carboxyphenyl)-1,3,5-triazine (90 mg) were ultrasonically dissolved in 12 mL dimethylformamide, 0.4 mL trifluoroacetic acid (equivalent to 26 molar equivalents of organic ligand) was added, and the mixture was ultrasonically mixed for 10 min. The resulting mixed solution was placed in a stainless steel reactor with a polytetrafluoroethylene substrate and reacted at 140°C for 12 h. After the reaction was completed, it was cooled to room temperature, centrifuged, washed several times with dimethylformamide and acetone, and dried to obtain white PCN-777 nanoparticles.

[0046] Example 2: Preparation of NU-1000 nanoparticles

[0047] ZrCl 4 (8 mg) and organic ligand 1,3,6,8-tetrakis(4′-carboxyphenyl)pyrene (2 mg) were dissolved in 2 mL dimethylformamide, 0.4 mL acetic acid (equivalent to 2330 molar equivalents of organic ligand) was added, and then 0.2 mL water was added, and the mixture was ultrasonically mixed for 15 min. The resulting mixed solution was placed in a stainless steel reactor with a polytetrafluoroethylene substrate and reacted at 90°C for 1 h. After the reaction was completed, it was cooled to room temperature, centrifuged, and the solvent was exchanged several times with dimethylformamide and ethanol, respectively, and yellow NU-1000 nanoparticles were obtained after drying.

[0048] Example 3: Preparation of Avermectin PCN-777 Nanopesticide Controlled Release Agent Encapsulated by Sodium Lignosulfonate

[0049] The synthesized PCN-777 nanoparticles (140 mg) were dispersed in 25 mL of acetone or ethanol, 500 mg of avermectin active ingredient was added, and the mixed solution was stirred at room temperature in the dark for 24 h. Centrifugation was performed to obtain PCN-777 nanoparticles loaded with avermectin. Subsequently, the drug-loaded PCN-777 nanoparticles were immediately dispersed in 25 mL of an aqueous solution containing sodium lignin sulfonate (6 mg / mL), and the mixed solution was stirred at room temperature in the dark for 24 h. Then centrifugation was performed to remove the unbound sodium lignin sulfonate, and freeze-dried to obtain the sodium lignin sulfonate-encapsulated avermectin PCN-777 nanopesticide controlled release agent.

[0050] Example 4: Preparation of Avermectin PCN-777 Nanopesticide Controlled Release Agent Dually Encapsulated by Sodium Lignosulfonate and Chitosan

[0051] The sodium lignin sulfonate encapsulated Avermectin PCN-777M nano-pesticide controlled-release agent obtained in Example 3 was immediately dispersed in 25 mL of an aqueous solution (6 mg / mL) containing chitosan without drying, and the mixed solution was stirred at room temperature for 15 minutes. Then, it was centrifuged, separated, washed, unbound chitosan was removed, and freeze-dried to obtain a sodium lignin sulfonate and chitosan double-encapsulated Avermectin PCN-777 nano-pesticide controlled-release agent.

[0052] Example 5: Preparation of Nano-pesticide Controlled Release Agent of Emamectin Benzoate PCN-777 Dually Encapsulated by Sodium Lignosulfonate and Chitosan

[0053] Except that the active ingredient of emamectin benzoate is used instead of the active ingredient of avermectin, the rest of the preparation method is the same as that of Example 3 and Example 4.

[0054] Example 6: Preparation of PCN-777 nanopesticide controlled-release agent containing emamectin benzoate and high-efficiency cypermethrin double-encapsulated by sodium lignin sulfonate and chitosan

[0055] The preparation method is the same as that in Example 5, except that the active ingredients of emamectin benzoate and highly effective cypermethrin (mass ratio 9:1) are used instead of the pure active ingredient of emamectin benzoate.

[0056] Example 7: Preparation of Pyraclostrobin PCN-777 Nanopesticide Controlled Release Agent Dually Encapsulated by Calcium Lignosulfonate and Chitosan

[0057] Except that pyraclostrobin is used as the active ingredient instead of avermectin, and calcium lignin sulfonate is used instead of sodium lignin sulfonate, the rest of the preparation method is the same as that of Example 3 and Example 4.

[0058] Example 8: Preparation of Avermectin NU-1000 Nanopesticide Controlled Release Agent Dually Encapsulated by Sodium Lignosulfonate and Chitosan

[0059] Except that NU-1000 nanoparticles are used instead of PCN-777 nanoparticles, the rest of the preparation method is the same as that of Example 3 and Example 4.

[0060] Example 9: UV degradation of avermectin PCN-777 nanopesticide controlled release agent double encapsulated by sodium lignin sulfonate and chitosan

[0061] 200 mg of sodium lignin sulfonate and chitosan double-encapsulated avermectin PCN-777 nanopesticide controlled release agent was dispersed in 10 mL of water. 1 mL of the nanopesticide dispersion was ultrasonically homogenized and spread on the surface of each culture dish with a diameter of 6 cm, and placed in the dark to dry naturally. Then, the culture dish with the nanopesticide controlled release agent was placed 20 cm away from a 254 nm ultraviolet lamp (36 W) for irradiation. After different times of ultraviolet light irradiation, the culture dishes with the nanopesticide controlled release agent were taken out one by one, washed and extracted with acetone, and the undegraded avermectin was determined by high performance liquid chromatography.

[0062] Example 10: Pesticide controlled release from nanopesticide controlled release agent

[0063] Multiple portions of sodium lignin sulfonate and chitosan double-encapsulated avermectin PCN-777 nanopesticide controlled-release agent (30 mg) prepared in Example 4 were weighed, dispersed in 2 mL of an aqueous solution containing ethanol (ethanol / water, 1:4, v / v) and 0.1% Tween-80, respectively, encapsulated in different dialysis bags (MWCO, 8000), and then placed in 148 mL of an aqueous solution containing ethanol (ethanol / water, 1:4, v / v) and 0.1% Tween-80 with different pH values ​​(pH 5.0, pH 7.0, pH 9.0), different contents of laccase (0.8 and 1.5 U / mL, pH 5.0), different concentrations of phosphate (1 and 3 mM, pH 7.0), and different concentrations of phytic acid (1 and 3 mM, pH 7.0). At different time intervals, 1 mL of the released sample solution was taken out and an equal volume of the corresponding fresh solution was added to keep the total volume unchanged. The content of the released pesticide active ingredient was determined by high performance liquid chromatography. Finally, the released pesticide was expressed by the cumulative release rate of the pesticide.

[0064] Figure 1 The chemical structure of 2,4,6-tris(4′-carboxyphenyl)-1,3,5-triazine, an organic ligand for preparing PCN-777.

[0065] Figure 2 Scanning electron microscope photos show that the PCN-777 nanoparticles prepared in Example 1 are polyhedral in shape with an average size of about 250 nm; the avermectin PCN-777 nanopesticide controlled-release agent (AVM@PCN-777@SL / CS) double-encapsulated with sodium lignin sulfonate and chitosan prepared in Example 4 maintains a polyhedral shape with an average size of about 250 nm.

[0066] Figure 3The X-ray diffraction (XRD) pattern of the PCN-777 nanoparticles prepared in Example 1 perfectly matches the theoretically fitted XRD pattern, confirming that the structure of the obtained nanoparticles is PCN-777; after pesticide loading, sodium lignin sulfonate and chitosan encapsulation, the MOF structure of the PCN-777 nanoparticles loaded with avermectin (AVM@PCN-777) prepared in Example 3 and the avermectin PCN-777 nanopesticide controlled release agent doubly encapsulated with sodium lignin sulfonate and chitosan (AVM@PCN-777@SL / CS) prepared in Example 4 remains unchanged, but the introduction of these amorphous phase substances causes the corresponding XRD diffraction peak intensity to gradually decrease.

[0067] Figure 4 The dynamic light scattering particle size distribution shows that the average hydration diameter of the PCN-777 nanoparticles prepared in Example 1 is 271 nm, and the average hydration diameter of the avermectin PCN-777 nanopesticide controlled-release agent doubly encapsulated with sodium lignin sulfonate and chitosan prepared in Example 4 is 308 nm, indicating the encapsulation of sodium lignin sulfonate and chitosan on the surface of PCN-777 nanoparticles.

[0068] Figure 5 The zeta potential of the PCN-777 nanoparticles prepared in Example 1 is 30.9 mV, indicating that there are coordination unsaturated Zr IV site; the zeta potential of the PCN-777 nanoparticles loaded with avermectin prepared in Example 3 was 14.5 mV, indicating the loading of the pesticide; the zeta potential of the sodium lignin sulfonate-encapsulated avermectin PCN-777 nanopesticide controlled-release agent (AVM@PCN-777@SL) prepared in Example 3 was -21.4 mV, indicating that sodium lignin sulfonate was encapsulated on the surface of the drug-loaded PCN-777 nanoparticles; the zeta potential of the avermectin PCN-777 nanopesticide controlled-release agent double-encapsulated with sodium lignin sulfonate and chitosan prepared in Example 4 was 29.9 mV, indicating that chitosan was further encapsulated on the surface of the drug-loaded PCN-777 nanoparticles encapsulated with sodium lignin sulfonate.

[0069] Figure 6 The results of nitrogen adsorption-desorption isotherms showed that the BET specific surface area of ​​PCN-777 nanoparticles was 725 m 2 / g, the BET specific surface areas of PCN-777 nanoparticles loaded with avermectin and avermectin PCN-777 nanopesticide controlled release agent double encapsulated with sodium lignin sulfonate and chitosan were reduced to 26 and 19 m 2 / g, indicating that the loading of pesticides, encapsulation of sodium lignin sulfonate and chitosan led to the filling and blocking of the mesoporous channels of PCN-777. The corresponding pore size distribution diagram shows that PCN-777 nanoparticles have larger mesopores of about 3 nm, and the pore size measured by the BJH method (about 3 nm) is smaller than the 3.5 nm mesoporous cage of the PCN-777 crystal structure; the mesoporous channels of PCN-777 nanoparticles loaded with avermectin and the avermectin PCN-777 nanopesticide controlled release agent double encapsulated with sodium lignin sulfonate and chitosan are filled and blocked.

[0070] Figure 7 The thermogravimetric analysis curve of PCN-777 nanoparticles showed that the weight loss of PCN-777 nanoparticles was less than the theoretical decomposition weight loss, indicating that PCN-777 nanoparticles have unsaturated Zr IV Site; The weight loss of PCN-777 nanoparticles loaded with avermectin and avermectin PCN-777 nanopesticide controlled-release agent double-encapsulated with sodium lignin sulfonate and chitosan illustrates the loading of pesticides, sodium lignin sulfonate and chitosan encapsulation. Using high-performance liquid chromatography, the pesticide loading in the double-encapsulated MOF nanopesticide controlled-release agent is 25% (mass percentage). The high pesticide loading enables low-concentration MOF nanopesticide controlled-release formulations to achieve the effect of preventing and controlling pests and diseases, reducing the production cost of users and reducing the difficulty of formulation in preparation and spraying.

[0071] Figure 8 Sodium lignin sulfonate, chitosan, avermectin original drug, organic ligand H 3 UV-visible absorption spectra of avermectin PCN-777 nanopesticide controlled-release agent double-encapsulated by TATB, PCN-777 nanoparticles, sodium lignin sulfonate and chitosan. Sodium lignin sulfonate and organic ligands have strong absorption of ultraviolet light. Obviously, PCN-777 nanoparticles and MOF nanopesticide controlled-release agent have strong absorption of ultraviolet light, which can protect the loaded avermectin from ultraviolet light degradation by sunlight.

[0072] Fig. 9 UV degradation curve of avermectin of avermectin original drug and avermectin PCN-777 nano pesticide controlled release agent double encapsulated with sodium lignin sulfonate and chitosan (Example 9). After 72 hours of UV irradiation, only 6.6% of avermectin original drug was not degraded by UV light, while 53.0% of avermectin active ingredients in MOF nano pesticide controlled release agent were still retained, and the anti-UV degradation ability was improved by 8 times.

[0073] Fig.10a~d are respectively the premature release of the pesticide of the avermectin PCN-777 nano-pesticide controlled-release agent double-encapsulated with sodium lignin sulfonate and chitosan prepared in Example 4 without stimulation conditions, and the controlled release curve of the pesticide in response to acidic, alkaline, phosphate, and phytic acid (PA) stimulation (Example 10). In an aqueous solution containing ethanol (ethanol / water, 1:4, v / v) and 0.1% Tween-80, without any stimulation conditions, the double-encapsulated avermectin PCN-777 nano-pesticide controlled-release agent showed a lower premature release of pesticide (pH 7.0), and the cumulative release rate of pesticide in 96 hours was only 9.2% ( Fig.10 a); Under acidic conditions (pH 5.0), the cumulative pesticide release rate for 96 h was 18.9%, compared with the 96 h cumulative pesticide release rate of 21.8% of the avermectin PCN-777 nanopesticide controlled release agent encapsulated with sodium lignin sulfonate prepared in Example 3, under acidic conditions, the double encapsulated MOF nanopesticide controlled release agent mainly removed the chitosan encapsulation, the sodium lignin sulfonate encapsulation was not affected, and the pesticide release rate was low; Under alkaline conditions (pH 9.0), the cumulative pesticide release rate for 96 h was 52.5%, mainly because the PCN-777 structure was partially destroyed and the pesticide was released. Under the condition of pH 5.0, where the laccase activity was the highest, 0.8 and 1.5 U / mL laccase caused the 72 h cumulative pesticide release rate of the double encapsulated MOF nanopesticide controlled release agent to increase from 18.3% to 44.9% and 57.8%, respectively ( Fig.10 b). In the presence of phosphate, the cumulative release rates of pesticides for 96 h were 35.8% and 53.7% for 1 and 3 mM phosphate, respectively ( Fig.10 c). In the presence of phytic acid, the cumulative release rates of pesticides for 1 and 3 mM phytic acid were 44.5% and 61.6% for 96 h, respectively ( Fig.10 d).

[0074] Fig.11 Chemical structure of 1,3,6,8-tetrakis(4′-carboxyphenyl)pyrene, an organic ligand used to prepare NU-1000.

[0075] Fig.12 This is a scanning electron microscope photograph of the NU-1000 nanoparticles prepared in Example 2, which are shaped like a rugby ball and have an average major axis size of about 110 nm.

[0076] Fig.13 The XRD pattern of the NU-1000 nanoparticles prepared in Example 2 perfectly matches the theoretically fitted XRD pattern, confirming that the prepared nanoparticles are NU-1000.

[0077] Fig.14The zeta potential of the NU-1000 nanoparticles prepared in Example 2 is 28.9 mV, indicating that there are coordination unsaturated Zr IV sites, which is conducive to the coordination and encapsulation of lignin sulfonate on the surface of drug-loaded NU-1000 nanoparticles.

[0078] Fig.15 The nitrogen adsorption-desorption isotherm and pore size distribution of the NU-1000 nanoparticles prepared in Example 2. The BET specific surface area of ​​the NU-1000 nanoparticles is 1302 m 2 / g, the mesopore size measured by the BJH method (about 2.3 nm) is smaller than the 3 nm mesoporous cage of the NU-1000 crystal structure, which can load larger pesticide molecules into the NU-1000 mesoporous channels.

[0079] The above-described embodiments are only preferred embodiments of the present invention and are not intended to limit the present invention. It should be noted that for those skilled in the art, the present invention may have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention, including loading other pesticide active ingredients for the preparation of MOF nanopesticide controlled-release agents, shall be included in the scope of protection of the present invention.

Claims

1. A method for preparing a metal organic framework nano pesticide controlled release agent, It is characterized in that The following steps are involved: Step 1: dispersing the metal organic framework nanomaterial in an organic solvent A, adding the pesticide active ingredient, stirring at room temperature, loading the pesticide active ingredient into the pores of the metal organic framework nanomaterial, centrifuging, and obtaining the drug-loaded metal organic framework nanomaterial; the metal organic framework nanomaterial is PCN-777 nanoparticles; Step 2: dispersing the drug-loaded metal organic framework nanomaterial obtained in step 1 in an aqueous solution containing lignin sulfonate, stirring at room temperature, and centrifuging to obtain a lignin sulfonate-encapsulated metal organic framework nanopesticide controlled-release agent; Step 3: Disperse the lignin sulfonate encapsulated metal organic framework nanopesticide obtained in step 2 in an aqueous solution containing chitosan, stir at room temperature, centrifuge, separate, wash and dry to obtain the target product, lignin sulfonate and chitosan double encapsulated metal organic framework nanopesticide controlled release agent.

2. The method for preparing the metal organic framework nano pesticide controlled release agent according to claim 1, Features: The preparation method of the PCN-777 nanoparticles comprises the following steps: 2 8H 2 O and the organic ligand 2,4,6-tris(4′-carboxyphenyl)-1,3,5-triazine are dissolved in an organic solvent B at a molar ratio of 10 to 2:1, 10 to 55 molar equivalents of trifluoroacetic acid of the organic ligand are added, the mixture is evenly mixed, the mixture is placed in a reaction kettle, the reaction is carried out at 110 to 160° C. for 5 to 24 h, the mixture is cooled to room temperature, the mixture is centrifuged, the mixture is washed with organic solvent B and organic solvent A, respectively, and the PCN-777 nanoparticles are obtained after drying.

3. The method for preparing the metal organic framework nano pesticide controlled release agent according to claim 1, Features: The organic solvent A is at least one of ethanol and acetone.

4. The method for preparing the metal organic framework nano pesticide controlled release agent according to claim 2 or 3, Features: The organic solvent B is at least one of dimethylformamide and diethylformamide.

5. The method for preparing the metal organic framework nano pesticide controlled release agent according to claim 1, Features: The active ingredient of the pesticide is one of avermectin, avermectin benzoate, high-efficiency cypermethrin and pyraclostrobin, or a mixture of two or more thereof.

6. The method for preparing the metal organic framework nano pesticide controlled release agent according to claim 1, Features: The mass ratio of the metal organic framework nanomaterial to the pesticide active ingredient in step 1 is 1:0.5-10; the concentration of the pesticide active ingredient in the organic solvent A is 4-100 g / L.

7. The method for preparing the metal organic framework nano pesticide controlled release agent according to claim 1, It is characterized in that The lignin sulfonate is at least one of sodium lignin sulfonate and calcium lignin sulfonate; the mass ratio of the lignin sulfonate to chitosan is 1:0-5; the mass ratio of the metal organic framework nanomaterial to the lignin sulfonate is 1:0.2-5.

8. Application of the product obtained by the preparation method of the metal organic framework nano pesticide controlled release agent according to any one of claims 1 to 3 in pesticide control, It is characterized in that The release of pesticides is controlled by environmental factors; the environmental factors are one or a combination of two or more of pH value, laccase, phosphate and phytic acid.

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