Nano slow-release pesticide fertilizer with polydopamine coating and preparation method of nano slow-release pesticide fertilizer

Abstract

The invention belongs to the technical field of slow release of pesticide fertilizers, and particularly relates to a nano slow-release pesticide fertilizer with a polydopamine coating and a preparation method of the nano slow-release pesticide fertilizer. According to the nano slow-release pesticide fertilizer, a simple one-pot method is adopted, coordination assembly between zinc ions and imidazole-2-formaldehyde is utilized, a bactericide and a fertilizer are packaged in a synthesized zinc-based nano carrier ZIF-90, and finally the carrier is coated with a layer of polydopamine. The nano slow-release pesticide fertilizer is prepared from the following components in percentage by mass: 45 to 60 weight percent of zinc-based nano carrier ZIF-90, 15 to 30 weight percent of pesticide fertilizer and 5 to 15 weight percent of coating material polydopamine. The nano slow-release pesticide fertilizer prepared by the invention has the characteristics of small average particle size, good biocompatibility and environmental safety, and has a good application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of sustained-release medicinal fertilizers, and in particular relates to a nano sustained-release medicinal fertilizer with a polydopamine coating and a preparation method thereof. Background Art

[0002] Fertilizers are chemicals that can provide nutrients for crop growth and development, improve soil properties, and increase crop yield and quality. Pesticides are chemical agents used to prevent and control crop diseases and pests, regulate plant growth, and increase crop yield and quality. However, the loss of large amounts of fertilizers and pesticides not only leads to economic losses, but may also cause serious pollution of water, soil, and air, thereby threatening human health.

[0003] In order to solve this problem, the development of slow-release fertilizers is particularly critical. Compared with traditional slow-release pesticides or fertilizers, slow-release fertilizers can not only provide the nutrients required for the normal growth of crops, but also effectively kill pests, pathogens, and harmful animals and plants, thereby ensuring the healthy growth of crops and increasing the overall agricultural output. In addition, slow-release fertilizers can also improve the utilization rate of pesticides and fertilizers at the same time, reducing waste caused by excessive use. More importantly, it can prevent pesticides and fertilizers from remaining in the soil due to excessive concentrations, thereby preventing soil pollution and ensuring the sustainable use of soil.

[0004] At present, most of the slow-release fertilizers on the market are in the form of fertilizer granules. These fertilizer granules are usually prepared in the following ways: first, an inert porous material (such as zeolite) can be used as a physical carrier, the role of which is to fix the pesticide and fertilizer in the porous structure inside it; second, fertilizer particles can be used as carriers, and then the pesticide is loaded on it and a coating process is performed; third, the pesticide and fertilizer can be directly coated; finally, the pesticide active ingredient particles, compound fertilizer particles and fillers can be mixed and directly coated to prepare slow-release fertilizers. However, most of these slow-release fertilizers are prepared from non-degradable, toxic and environmentally unfriendly raw materials. Therefore, there is an urgent need to develop a degradable, non-toxic and environmentally friendly slow-release fertilizer. Summary of the invention

[0005] In view of this, in order to solve this problem, the purpose of the present invention is to provide a polydopamine-coated nano-slow-release medicinal fertilizer and a preparation method thereof, wherein the nano-slow-release medicinal fertilizer is a slow-release medicinal fertilizer with a zinc-based metal organic framework as a carrier, has good biocompatibility, is environmentally friendly and degradable, and has longer medicinal and fertilizer effects.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The first technical purpose of the present invention is to provide a polydopamine-coated nano-slow-release medicinal fertilizer, wherein the nano-slow-release medicinal fertilizer uses ZIF-90 as a carrier, the inside of the carrier wraps the medicinal fertilizer, and the outside of the carrier is coated with polydopamine; and the nano-slow-release medicinal fertilizer includes the following components by mass percentage:

[0008] 45-60wt% of zinc-based nanocarrier ZIF-90, 15-30wt% of fertilizer and 5-15wt% of polydopamine.

[0009] It should be noted that dopamine is an endogenous nitrogen-containing organic compound that can be polymerized to form polydopamine. The schematic diagram of its synthesis is as follows:

[0010]

[0011] Polydopamine has strong adhesion and chemical activity, and can react with a variety of functional groups. Although research has developed medicinal fertilizer products with good sustained-release effects, these products often require the use of polymer materials as templates and then attach polydopamine to their surfaces, which undoubtedly puts higher requirements on the safety of medicinal fertilizer raw materials. ZIF-90, as a type of metal organic framework material (MOFs), is composed of zinc ions and imidazole-2-carboxaldehyde, and has the characteristics of good biocompatibility, high loading efficiency, good sustained-release performance, and large specific surface area. As a drug fertilizer delivery carrier, ZIF-90 shows great application potential.

[0012] Optionally, the pesticide fertilizer is composed of a fungicide and a fertilizer in a mass ratio of 5:3; the fungicide is one or more combinations of lothiocarb, tebuconazole, and difenoconazole, and the fertilizer is one or more combinations of urea, ammonium bicarbonate, potassium chloride, ammonium chloride, nitrophosphate, superphosphate, and ammonium phosphate.

[0013] Optionally, the polydopamine is composed of dihydroxyindole, indoledione and dopamine basic units.

[0014] The second technical purpose of the present invention is to provide a method for preparing the nano slow-release medicinal fertilizer with polydopamine coating as described above.

[0015] The preparation method of the polydopamine-coated nano slow-release fertilizer comprises the following steps:

[0016] 1) The zinc-based nanocarrier ZIF-90 encapsulating the fertilizer was prepared by a simple one-pot method:

[0017] A certain amount of zinc acetate and medicinal fertilizer are added to N, N-dimethylformamide solution to obtain solution A; an appropriate amount of imidazole-2-carboxaldehyde is dissolved in N, N-dimethylformamide solution to obtain solution B; solution B is added to solution A under stirring, reacted for a period of time, the obtained mixture is collected by centrifugation, washed three times with methanol, and finally dried to obtain the zinc-based nanocarrier ZIF-90 with the medicinal fertilizer encapsulated inside.

[0018] 2) The polydopamine coated on the outside of the carrier is synthesized by cross-linking reaction of carboxyl and amino groups using a coupling agent:

[0019] The zinc-based nanocarrier ZIF-90 with internally encapsulated medicinal fertilizer prepared in step 1) is dispersed in water, hydrogen peroxide is added, reacted at room temperature for 1 hour, centrifuged and washed with water to obtain the carboxylated zinc-based nanocarrier ZIF-90 encapsulating medicinal fertilizer; 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride is added to the aqueous solution of the zinc-based nanocarrier ZIF-90 encapsulating the medicinal fertilizer (solution C), activated for 1 hour, and then the dopamine hydrochloride aqueous solution containing N-hydroxysuccinimide (solution D) is added to solution C, and the mixed solution is reacted for 24 hours under stirring; finally, the polydopamine-coated nano slow-release medicinal fertilizer is obtained by centrifugation, washing and drying.

[0020] Optionally, in step 1), the ratio of zinc acetate to imidazole-2-carboxaldehyde added is 2:3 (w / w); and the volume ratio of solution A to solution B is 1:1.

[0021] Further, the reaction system conditions in step 1) are 25°C, a rotation speed of 300 rpm and an addition rate of 4 mL / min. Optionally, in step 2), the molar concentration of hydrogen peroxide is 20.5 mmol / L, the mass ratio of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride to N-hydroxysuccinimide is 5:3, and the mass ratio of dopamine to carboxylated zinc-based nanocarrier ZIF-90 encapsulating medicinal fertilizer is 1:4.

[0022] Furthermore, in the step 2), the volume ratio of solution C to solution D is 5:3.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1) The present invention has developed a polydopamine-coated nano slow-release fertilizer, which uses ZIF-90 as a carrier, the inside of the carrier wraps the fertilizer, and the outside of the carrier is coated with polydopamine. The fertilizer is encapsulated in the zinc-based nanocarrier ZIF-90, which prolongs the time of drug and fertilizer effects, avoids the waste of fertilizers and pesticides, improves their utilization efficiency, and has an intelligent controlled release effect.

[0025] 2) The present invention uses the zinc-based nanocarrier ZIF-90 as the main material of the nano slow-release fertilizer, which has good biocompatibility and can provide the essential micronutrient zinc and important nutrient element nitrogen for plant growth and development, improve soil fertility and promote plant growth.

[0026] 3) The present invention uses polydopamine as a multifunctional coating to improve the utilization efficiency of fertilizers, reduce the impact on the environment, and contribute to the sustainable development of modern agriculture. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0028] Figure 1 is a SEM image of the zinc-based nanocarrier ZIF-90 prepared by the present invention;

[0029] Figure 2 is the SEM image of the zinc-based nanocarrier ZIF-90 after polydopamine coating. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The word "embodiment" used here as an "exemplary" does not necessarily mean that any embodiment described is superior to or better than other embodiments. Unless otherwise specified, the performance index tests in the embodiments of this application are performed using conventional test methods in the art. It should be understood that the terms described in this application are only used to describe specific implementation methods and are not used to limit the content disclosed in this application.

[0032] Unless otherwise specified, the technical and scientific terms used in this document have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs; other experimental methods and technical means not specifically specified in this application refer to experimental methods and technical means commonly used by ordinary technicians in this field.

[0033] In order to better illustrate the content of the present application, numerous specific details are provided in the specific examples below. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In the embodiments, some methods, means, instruments, equipment, etc. well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present application.

[0034] Under the premise of no conflict, the technical features disclosed in the embodiments of the present application can be combined arbitrarily, and the resulting technical solutions belong to the contents disclosed in the embodiments of the present application.

[0035] The invention discloses a nano slow-release medicinal fertilizer with a polydopamine coating and a preparation method thereof.

[0036] In order to better understand the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as a limitation of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above invention content are also considered to fall within the protection scope of the present invention.

[0037] Example 1

[0038] (1) 0.2 g of zinc acetate, 0.5 g of lothiocarbamide and 0.3 g of urea were added to 20 mL of N, N-dimethylformamide solution and ultrasonicated for 5 minutes to fully dissolve them to obtain solution A; 0.3 g of imidazole-2-carboxaldehyde was dissolved in 20 mL of N, N-dimethylformamide solution to obtain solution B; solution B was added to solution A at 25°C, 300 rpm and 4 mL / min, and stirring was continued for 30 minutes after the addition was completed. The resulting mixture was collected by centrifugation, washed three times with methanol, and finally dried to obtain a zinc-based nanocarrier with drug fertilizer encapsulated inside, which was labeled as LJ-ZIF-90.

[0039] (2) dissolving 0.41 mmol of hydrogen peroxide in 20 mL of distilled water to obtain a hydrogen peroxide solution; dispersing 0.1 g of LJ-ZIF-90 in 30 mL of water, adding the hydrogen peroxide solution thereto under magnetic stirring, reacting for 24 hours, collecting the product by centrifugation, washing with water, and finally drying to obtain carboxylated LJ-ZIF-90;

[0040] (3) 0.6 g of carboxylated LJ-ZIF-90 was dispersed in 50 mL of water, 0.6 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was added thereto, and the mixture was activated for 1 hour to obtain solution C; 0.15 g of dopamine hydrochloride and 0.36 g of N-hydroxysuccinimide were dissolved in 30 mL of water until they were completely dissolved to obtain solution D; solution D was added to solution C under stirring at 400 rpm, and after reacting for 24 hours, the precipitate was collected by centrifugation, washed with water, and finally dried to obtain a polydopamine-coated nano-sustained-release fertilizer.

[0041] Example 2

[0042] (1) 0.2 g of zinc acetate, 0.5 g of clofothionil, 0.1 g of urea and 0.2 g of ammonium phosphate were added to 20 mL of N, N-dimethylformamide solution and ultrasonicated for 5 minutes to fully dissolve them to obtain solution A; 0.3 g of imidazole-2-carboxaldehyde was dissolved in 20 mL of N, N-dimethylformamide solution to obtain solution B; solution B was added to solution A at 25°C, 300 rpm and 4 mL / min, and stirring was continued for 30 minutes after the addition was completed. The resulting mixture was collected by centrifugation, washed three times with methanol, and finally dried to obtain a zinc-based nanocarrier with drug fertilizer encapsulated inside, which was labeled as LJ-ZIF-90.

[0043] (2) dissolving 0.41 mmol of hydrogen peroxide in 20 mL of distilled water to obtain a hydrogen peroxide solution; dispersing 0.1 g of LJ-ZIF-90 in 30 mL of water, adding the hydrogen peroxide solution thereto under magnetic stirring, reacting for 24 hours, collecting the product by centrifugation, washing with water, and finally drying to obtain carboxylated LJ-ZIF-90;

[0044] (3) 0.6 g of carboxylated LJ-ZIF-90 was dispersed in 50 mL of water, 0.6 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was added thereto, and the mixture was activated for 1 hour to obtain solution C; 0.15 g of dopamine hydrochloride and 0.36 g of N-hydroxysuccinimide were dissolved in 30 mL of water until they were completely dissolved to obtain solution D; solution D was added to solution C under stirring at 400 rpm, and after reacting for 24 hours, the precipitate was collected by centrifugation, washed with water, and finally dried to obtain a polydopamine-coated nano-sustained-release fertilizer.

[0045] Example 3

[0046] (1) 0.2 g of zinc acetate, 0.5 g of tebuconazole, 0.15 g of urea and 0.15 g of potassium chloride were added to 20 mL of N, N-dimethylformamide solution and ultrasonicated for 5 minutes to fully dissolve them to obtain solution A; 0.3 g of imidazole-2-carboxaldehyde was dissolved in 20 mL of N, N-dimethylformamide solution to obtain solution B; solution B was added to solution A at 25°C, 300 rpm and 4 mL / min, and stirring was continued for 30 minutes after the addition was completed. The resulting mixture was collected by centrifugation, washed three times with methanol, and finally dried to obtain a zinc-based nanocarrier with drug fertilizer encapsulated inside, which was marked as LJ-ZIF-90.

[0047] (2) dissolving 0.41 mmol of hydrogen peroxide in 20 mL of distilled water to obtain a hydrogen peroxide solution; dispersing 0.1 g of LJ-ZIF-90 in 30 mL of water, adding the hydrogen peroxide solution thereto under magnetic stirring, reacting for 24 hours, collecting the product by centrifugation, washing with water, and finally drying to obtain carboxylated LJ-ZIF-90;

[0048] (3) 0.6 g of carboxylated LJ-ZIF-90 was dispersed in 50 mL of water, 0.6 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was added thereto, and the mixture was activated for 1 hour to obtain solution C; 0.15 g of dopamine hydrochloride and 0.36 g of N-hydroxysuccinimide were dissolved in 30 mL of water until they were completely dissolved to obtain solution D; solution D was added to solution C under stirring at 400 rpm, and after reacting for 24 hours, the precipitate was collected by centrifugation, washed with water, and finally dried to obtain a polydopamine-coated nano-sustained-release fertilizer.

[0049] Example 4

[0050] (1) 0.2 g of zinc acetate, 0.5 g of tebuconazole and 0.3 g of potassium chloride were added to 20 mL of N, N-dimethylformamide solution, and ultrasonicated for 5 minutes to fully dissolve them to obtain solution A; 0.3 g of imidazole-2-carboxaldehyde was dissolved in 20 mL of N, N-dimethylformamide solution to obtain solution B; solution B was added to solution A at 25°C, 300 rpm and 4 mL / min, and stirring was continued for 30 minutes after the addition was completed. The resulting mixture was collected by centrifugation, washed three times with methanol, and finally dried to obtain a zinc-based nanocarrier with drug fertilizer encapsulated inside, which was marked as LJ-ZIF-90.

[0051] (2) dissolving 0.41 mmol of hydrogen peroxide in 20 mL of distilled water to obtain a hydrogen peroxide solution; dispersing 0.1 g of LJ-ZIF-90 in 30 mL of water, adding the hydrogen peroxide solution thereto under magnetic stirring, reacting for 24 hours, collecting the product by centrifugation, washing with water, and finally drying to obtain carboxylated LJ-ZIF-90;

[0052] (3) 0.6 g of carboxylated LJ-ZIF-90 was dispersed in 50 mL of water, 0.6 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was added thereto, and the mixture was activated for 1 hour to obtain solution C; 0.15 g of dopamine hydrochloride and 0.36 g of N-hydroxysuccinimide were dissolved in 30 mL of water until they were completely dissolved to obtain solution D; solution D was added to solution C under stirring at 400 rpm, and after reacting for 24 hours, the precipitate was collected by centrifugation, washed with water, and finally dried to obtain a polydopamine-coated nano-sustained-release fertilizer.

[0053] Example 5

[0054] (1) 0.2 g of zinc acetate, 0.5 g of difenoconazole, 0.2 g of urea and 0.1 g of superphosphate were added to 20 mL of N, N-dimethylformamide solution and ultrasonicated for 5 minutes to fully dissolve them to obtain solution A; 0.3 g of imidazole-2-carboxaldehyde was dissolved in 20 mL of N, N-dimethylformamide solution to obtain solution B; solution B was added to solution A at 25°C, 300 rpm and 4 mL / min, and stirring was continued for 30 minutes after the addition was completed. The resulting mixture was collected by centrifugation, washed three times with methanol, and finally dried to obtain a zinc-based nanocarrier with drug fertilizer encapsulated inside, which was marked as LJ-ZIF-90.

[0055] (2) dissolving 0.41 mmol of hydrogen peroxide in 20 mL of distilled water to obtain a hydrogen peroxide solution; dispersing 0.1 g of LJ-ZIF-90 in 30 mL of water, adding the hydrogen peroxide solution thereto under magnetic stirring, reacting for 24 hours, collecting the product by centrifugation, washing with water, and finally drying to obtain carboxylated LJ-ZIF-90;

[0056] (3) 0.6 g of carboxylated LJ-ZIF-90 was dispersed in 50 mL of water, 0.6 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was added thereto, and the mixture was activated for 1 hour to obtain solution C; 0.15 g of dopamine hydrochloride and 0.36 g of N-hydroxysuccinimide were dissolved in 30 mL of water until they were completely dissolved to obtain solution D; solution D was added to solution C under stirring at 400 rpm, and after reacting for 24 hours, the precipitate was collected by centrifugation, washed with water, and finally dried to obtain a polydopamine-coated nano-sustained-release fertilizer.

[0057] Example 6

[0058] (1) 0.2 g of zinc acetate, 0.5 g of difenoconazole, and 0.3 g of superphosphate were added to 20 mL of N, N-dimethylformamide solution, and ultrasonicated for 5 minutes to fully dissolve them to obtain solution A; 0.3 g of imidazole-2-carboxaldehyde was dissolved in 20 mL of N, N-dimethylformamide solution to obtain solution B; solution B was added to solution A at 25°C, 300 rpm, and 4 mL / min. After the addition, stirring was continued for 30 minutes, the resulting mixture was collected by centrifugation, washed three times with methanol, and finally dried to obtain a zinc-based nanocarrier with drug fertilizer encapsulated inside, which was labeled as LJ-ZIF-90.

[0059] (2) dissolving 0.41 mmol of hydrogen peroxide in 20 mL of distilled water to obtain a hydrogen peroxide solution; dispersing 0.1 g of LJ-ZIF-90 in 30 mL of water, adding the hydrogen peroxide solution thereto under magnetic stirring, reacting for 24 hours, collecting the product by centrifugation, washing with water, and finally drying to obtain carboxylated LJ-ZIF-90;

[0060] (3) 0.6 g of carboxylated LJ-ZIF-90 was dispersed in 50 mL of water, 0.6 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was added thereto, and the mixture was activated for 1 hour to obtain solution C; 0.15 g of dopamine hydrochloride and 0.36 g of N-hydroxysuccinimide were dissolved in 30 mL of water until they were completely dissolved to obtain solution D; solution D was added to solution C under stirring at 400 rpm, and after reacting for 24 hours, the precipitate was collected by centrifugation, washed with water, and finally dried to obtain a polydopamine-coated nano-sustained-release fertilizer.

[0061] Example 7

[0062] (1) 0.1 g of zinc acetate, 0.5 g of clofothionil, 0.1 g of urea and 0.2 g of ammonium phosphate were added to 20 mL of N, N-dimethylformamide solution and ultrasonicated for 5 minutes to fully dissolve them to obtain solution A; 0.3 g of imidazole-2-carboxaldehyde was dissolved in 20 mL of N, N-dimethylformamide solution to obtain solution B; solution B was added to solution A at 25°C, 300 rpm and 4 mL / min, and stirring was continued for 30 minutes after the addition was completed. The resulting mixture was collected by centrifugation, washed three times with methanol, and finally dried to obtain a zinc-based nanocarrier with drug fertilizer encapsulated inside, which was labeled as LJ-ZIF-90.

[0063] (2) dissolving 0.41 mmol of hydrogen peroxide in 20 mL of distilled water to obtain a hydrogen peroxide solution; dispersing 0.1 g of LJ-ZIF-90 in 30 mL of water, adding the hydrogen peroxide solution thereto under magnetic stirring, reacting for 24 hours, collecting the product by centrifugation, washing with water, and finally drying to obtain carboxylated LJ-ZIF-90;

[0064] (3) 0.6 g of carboxylated LJ-ZIF-90 was dispersed in 50 mL of water, 0.6 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was added thereto, and the mixture was activated for 1 hour to obtain solution C; 0.15 g of dopamine hydrochloride and 0.36 g of N-hydroxysuccinimide were dissolved in 30 mL of water until they were completely dissolved to obtain solution D; solution D was added to solution C under stirring at 400 rpm, and after reacting for 24 hours, the precipitate was collected by centrifugation, washed with water, and finally dried to obtain a polydopamine-coated nano-sustained-release fertilizer.

[0065] Example 8

[0066] (1) 0.2 g of zinc acetate, 0.5 g of tebuconazole, 0.15 g of urea and 0.15 g of potassium chloride were added to 20 mL of N, N-dimethylformamide solution and ultrasonicated for 5 minutes to fully dissolve them to obtain solution A; 0.3 g of imidazole-2-carboxaldehyde was dissolved in 20 mL of N, N-dimethylformamide solution to obtain solution B; solution B was added to solution A at 40°C, 300 rpm and 4 mL / min, and stirring was continued for 30 minutes after the addition was completed. The resulting mixture was collected by centrifugation, washed three times with methanol, and finally dried to obtain a zinc-based nanocarrier with drug fertilizer encapsulated inside, which was marked as LJ-ZIF-90.

[0067] (2) dissolving 0.41 mmol of hydrogen peroxide in 20 mL of distilled water to obtain a hydrogen peroxide solution; dispersing 0.1 g of LJ-ZIF-90 in 30 mL of water, adding the hydrogen peroxide solution thereto under magnetic stirring, reacting for 24 hours, collecting the product by centrifugation, washing with water, and finally drying to obtain carboxylated LJ-ZIF-90;

[0068] (3) 0.6 g of carboxylated LJ-ZIF-90 was dispersed in 50 mL of water, 0.6 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was added thereto, and the mixture was activated for 1 hour to obtain solution C; 0.15 g of dopamine hydrochloride and 0.36 g of N-hydroxysuccinimide were dissolved in 30 mL of water until they were completely dissolved to obtain solution D; solution D was added to solution C under stirring at 400 rpm, and after reacting for 24 hours, the precipitate was collected by centrifugation, washed with water, and finally dried to obtain a polydopamine-coated nano-sustained-release fertilizer.

[0069] Example 9

[0070] (1) 0.2 g of zinc acetate, 0.5 g of difenoconazole, 0.2 g of urea and 0.1 g of superphosphate were added to 20 mL of N, N-dimethylformamide solution and ultrasonicated for 5 minutes to fully dissolve them to obtain solution A; 0.3 g of imidazole-2-carboxaldehyde was dissolved in 20 mL of N, N-dimethylformamide solution to obtain solution B; solution B was added to solution A at 25°C, 300 rpm and 4 mL / min, and stirring was continued for 30 minutes after the addition was completed. The resulting mixture was collected by centrifugation, washed three times with methanol, and finally dried to obtain a zinc-based nanocarrier with drug fertilizer encapsulated inside, which was marked as LJ-ZIF-90.

[0071] (2) dissolving 0.41 mmol of hydrogen peroxide in 20 mL of distilled water to obtain a hydrogen peroxide solution; dispersing 0.1 g of LJ-ZIF-90 in 30 mL of water, adding the hydrogen peroxide solution thereto under magnetic stirring, reacting for 24 hours, collecting the product by centrifugation, washing with water, and finally drying to obtain carboxylated LJ-ZIF-90;

[0072] (3) 0.6 g of carboxylated LJ-ZIF-90 was dispersed in 50 mL of water, 0.6 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was added thereto, and the mixture was activated for 1 hour to obtain solution C; 0.30 g of dopamine hydrochloride and 0.36 g of N-hydroxysuccinimide were dissolved in 30 mL of water until they were completely dissolved to obtain solution D; solution D was added to solution C under stirring at 400 rpm, and after reacting for 24 hours, the precipitate was collected by centrifugation, washed with water, and finally dried to obtain a polydopamine-coated nano-sustained-release fertilizer.

[0073] In order to further demonstrate the beneficial effects of the present invention and to better understand the present invention, the following comparative examples and test examples are used to further illustrate the technical features disclosed in the present invention, but they should not be understood as limiting the present invention. Other improvements made by those skilled in the art based on the above invention content without creative work are also considered to fall within the scope of protection of the present invention.

[0074] Comparative Example 1

[0075] The zinc-based nanocarrier LJ-ZIF-90 encapsulating the medicinal fertilizer is not coated with a coating, and the other steps are consistent with Example 1.

[0076] Comparative Example 2

[0077] The zinc-based nanocarrier LJ-ZIF-90 encapsulating the medicinal fertilizer is not coated with a coating, and the other steps are consistent with Example 3.

[0078] Comparative Example 3

[0079] The zinc-based nanocarrier LJ-ZIF-90 encapsulating the medicinal fertilizer is not coated with a coating, and the other steps are consistent with Example 5.

[0080] 20 g of samples of Examples 1-6 and Comparative Examples 1-3 were placed in a dialysis bag (molecular weight cutoff of 10000 g / mol), sealed with a rope and placed in a 1L beaker containing 400 mL of deionized water. Samples were taken at pre-set times (1d, 5d, 10d, 20d, 40d, 60d, 80d, 100d and 120d), and the pesticide content of the samples was detected using high performance liquid chromatography. The cumulative release rate of the pesticide in water of the nano slow-release fertilizers prepared in Examples 1-9 and Comparative Examples 1-3 was statistically analyzed.

[0081] Table 1 Pesticide cumulative release rate of nano slow-release fertilizer prepared in different embodiments

[0082]

[0083]

[0084] From the results in Table 1, we can see that the cumulative release rates of the pesticides in Examples 1-9 and Comparative Examples 1-3 both increase with time, and the cumulative release rate of the pesticides in Example 1-9 is lower than that in Comparative Examples 1-3 as a whole, and the cumulative release rate of the pesticides in Comparative Examples 1-3 is close to 100% at 120 days, while the pesticides in Example 1-9 only release about 75% to 85% of the total amount. This may be because the nano slow-release fertilizer in Comparative Examples 1-3 is not coated with polydopamine, resulting in a relatively fast release rate of the pesticide, which affects the slow-release effect.

[0085] In addition, there are certain differences in the cumulative release rate of pesticides between different embodiments, which may be due to the different interactions between different pesticides and zinc-based nanocarriers and the effects of different reaction conditions on the particle size of zinc-based nanocarriers. According to relevant literature reports, the host-guest interaction between pesticides and metal organic frameworks involves coordination bonds, hydrogen bonds, electrostatic interactions, π-π interactions and other special effects (e.g., hydrophobic effects and pore filling). Sun et al. found that there are coordination bonds and electrostatic interactions between tebuconazole and zinc-based metal organic frameworks. In the report of Ma et al., there is a coordination bond between pyraclostrobin and zirconium-based metal organic frameworks. In addition, Yang et al. reported that an increase in reaction temperature will lead to a significant increase in the particle size of ZIF-90-CD, while with the increase of β-CD-NH 2 With the increase of the ratio, the morphology of ZIF-90-CD becomes rougher and obvious agglomeration occurs.

[0086] The above results show that the nano slow-release pesticide fertilizers with polydopamine coatings prepared in the examples have good slow-release effects, can release pesticides continuously for a long time, and effectively prolong the efficacy time.

[0087] based on Figure 1 and Figure 2 The results of scanning electron microscopy show that the prepared zinc-based nanocarrier ZIF-90 has a crystalline structure, a dodecahedron, and a relatively smooth surface. The zinc-based nanocarrier ZIF-90 coated with polydopamine shows a subspherical shape with a rough surface, indicating that the reaction between polydopamine and the zinc-based nanocarrier ZIF-90 is successful.

[0088] The Nano Measurer particle size measurement software was used to perform particle size analysis on the above scanning electron microscope images. The results showed that the average particle size of the prepared zinc-based nanocarrier ZIF-90 was about 120nm, and after polydopamine coating, the average particle size increased to about 180nm, which is consistent with the scanning electron microscope results we observed earlier.

[0089] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A nano slow-release fertilizer with a polydopamine coating, characterized in that: The nano slow-release fertilizer uses ZIF-90 as a carrier, the inside of the carrier wraps the fertilizer, and the outside of the carrier is coated with polydopamine; and the nano slow-release fertilizer includes the following components by mass percentage: 45-60wt% of zinc-based nanocarrier ZIF-90, 15-30wt% of fertilizer and 5-15wt% of polydopamine.

2. The polydopamine-coated nano slow-release fertilizer according to claim 1, characterized in that: The pesticide fertilizer is composed of a fungicide and a fertilizer in a mass ratio of 5:3; the fungicide is one or more combinations of lothiocarb, tebuconazole, and difenoconazole, and the fertilizer is one or more combinations of urea, ammonium bicarbonate, potassium chloride, ammonium chloride, nitrophosphate, superphosphate, and ammonium phosphate.

3. A method for preparing the polydopamine-coated nano slow-release medicinal fertilizer as claimed in claim 1, characterized in that: The method specifically comprises the following steps: 1) The zinc-based nanocarrier ZIF-90 encapsulating the fertilizer was prepared by a simple one-pot method: Zinc acetate and medicinal fertilizer are added to N, N-dimethylformamide solution to obtain solution A; imidazole-2-carboxaldehyde is dissolved in N, N-dimethylformamide solution to obtain solution B; solution B is added to solution A under stirring, and the obtained mixture is collected by centrifugation after reaction, and washed three times with methanol, and finally dried to obtain zinc-based nanocarrier ZIF-90 with medicinal fertilizer encapsulated therein; 2) The polydopamine coated on the outside of the carrier is synthesized by cross-linking reaction of carboxyl and amino groups using a coupling agent: The zinc-based nanocarrier ZIF-90 with internally encapsulated medicinal fertilizer prepared in step 1) is dispersed in water, and hydrogen peroxide is added for reaction, followed by centrifugation and washing to obtain the carboxylated zinc-based nanocarrier ZIF-90 with encapsulated medicinal fertilizer; 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride is added to the aqueous solution of the carboxylated zinc-based nanocarrier ZIF-90 with encapsulated medicinal fertilizer (solution C), and activated for 1 hour, and then the dopamine hydrochloride aqueous solution containing N-hydroxysuccinimide (solution D) is added to solution C, and the mixed solution is reacted under stirring, and then centrifuged, washed, and dried to obtain the polydopamine-coated nano slow-release medicinal fertilizer.

4. The method for preparing the polydopamine-coated nano slow-release medicinal fertilizer according to claim 3, characterized in that: In the step 1), the ratio of zinc acetate to imidazole-2-carboxaldehyde added is 1:1 to 1:3 (w / w); the volume ratio of solution A to solution B is 1:

1.

5. The method for preparing the nano slow-release medicinal fertilizer with polydopamine coating according to claim 3 or 4, characterized in that: The reaction temperature in step 1) is 20°C to 60°C, the rotation speed is 300 rpm and the addition rate is 4 mL / min.

6. The method for preparing the polydopamine-coated nano slow-release medicinal fertilizer according to claim 3, characterized in that: In the step 2), the molar concentration of hydrogen peroxide is 20.5 mmol / L, the mass ratio of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride to N-hydroxysuccinimide is 5:3, and the mass ratio of dopamine to the carboxylated zinc-based nanocarrier ZIF-90 encapsulating the fertilizer is 1:4 to 2:

1.

7. The method for preparing the polydopamine-coated nano slow-release medicinal fertilizer according to claim 3 or 6, characterized in that: The reaction temperature in step 2) is room temperature, the reaction time of adding hydrogen peroxide is 1 hour, and the reaction time of the mixed solution is 24 hours.

8. The method for preparing the polydopamine-coated nano slow-release medicinal fertilizer according to claim 3, characterized in that: In the step 2), the volume ratio of solution C to solution D is 5:3.

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