Porous chitosan-azoxystrobin nano slow-release agent as well as preparation method and application thereof

Abstract

The invention belongs to the field of pesticide preparation, and particularly relates to a porous chitosan-azoxystrobin nano slow-release agent as well as a preparation method and application thereof. Comprising the following steps: S1, weighing paraffin, Span-80 and Tween-80, stirring and mixing, and heating and stirring to obtain an oil phase; s2, weighing azoxystrobin raw medicine, water, 1% acetic acid and chitosan, and stirring and mixing to obtain a water phase; and S3, slowly dripping the water phase into the oil phase, and mixing and emulsifying to obtain the emulsion. And S4, slowly adding glutaraldehyde l and anhydrous acetic acid into the emulsion, and continuously heating and stirring at 60 DEG C for 1 hour to obtain the porous chitosan-azoxystrobin nano slow-release agent emulsion. And S5, centrifuging the emulsion, and alternately washing with petroleum ether, dichloromethane or trichloromethane to obtain the porous chitosan-azoxystrobin nano slow-release agent. According to the invention, porous chitosan nanoparticles with uniform morphology and particle size are prepared at room temperature by adopting an interfacial polymerization method, and when the porous chitosan nanoparticles are used in the field, the lasting period of the pesticide can be prolonged, the pesticide application frequency is reduced, and the pesticide application amount is reduced.

Description

Technical Field

[0001] The invention belongs to the field of pesticide preparation, and specifically relates to a porous chitosan-azoxystrobin nano sustained-release agent and a preparation method and application thereof. Background Art

[0002] Azoxystrobin is a methoxyacrylate fungicide with the characteristics of high efficiency, systemicity and broad spectrum, and has been widely used in crop disease prevention and control. At present, the market dosage forms are mainly water-dispersible granules and suspensions, which have problems such as low effective utilization rate and short effective period, and a new formulation processing strategy is urgently needed.

[0003] Entering the 21st century, nanomaterials, with their excellent physical and chemical properties, have shown broad application prospects in the fields of agricultural production and plant nutrition. Domestic and foreign scholars have conducted multi-faceted research and exploration on nanopesticides. Studies have shown that nanopesticides can be divided into two categories. One is metal-based nanoparticles, which release metal particles by dissolution and show strong antibacterial activity through cytotoxicity and oxidative stress; the other is nanocarriers (such as nanocapsules, nanoparticles, etc.) that can carry pesticides for delivery, and most nanocarriers have high biocompatibility and strong stimulant responsiveness, which can achieve controlled release of pesticides and minimize the negative impact of pesticides on the environment. At present, there is no report on the sustained-release nanoparticle technology of myclobutanil. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a method for preparing a porous chitosan-azoxystrobin nano sustained-release agent, comprising the following steps:

[0005] (1) Weigh paraffin, Span-80, and Tween-80, heat and stir to obtain an oil phase;

[0006] (2) weighing azoxystrobin technical, water, 1% acetic acid, and chitosan, stirring and mixing to obtain an aqueous phase;

[0007] (3) slowly dripping the water phase into the oil phase, mixing and emulsifying to obtain an emulsion;

[0008] (4) adding glutaraldehyde and anhydrous acetic acid to the emulsion, and continuing heating and stirring to obtain a porous chitosan-azoxystrobin nano sustained-release agent emulsion;

[0009] (5) The emulsion is centrifuged and washed alternately with petroleum ether, dichloromethane or chloroform to obtain a porous chitosan-azoxystrobin nano sustained-release agent.

[0010] Furthermore, the volume mass ratio of the paraffin, Span-80, Tween-80, myclobutanil technical and chitosan is 80ml:1g:1g:0.5-1.5g:0.4g; the volume ratio of the paraffin, water, 1% acetic acid, glutaraldehyde and anhydrous acetic acid is 80:10:10:2:2.

[0011] Furthermore, the volume mass ratio of the paraffin, Span-80, Tween-80, azoxystrobin technical and chitosan is 80 ml: 1 g: 1 g: 1 g: 0.4 g.

[0012] Furthermore, the heating and stirring in step (1) is at 40° C. and 400 r / min for 30 min.

[0013] Furthermore, in step (3), the mixed emulsification reaction speed is 500-800 r / min, and the reaction time is 30-90 min.

[0014] Furthermore, in step (3), the mixed emulsification reaction speed is 600 r / min and the reaction time is 60 min.

[0015] The invention also provides a porous chitosan-azoxystrobin nano sustained-release agent, which is prepared by the above preparation method.

[0016] The present invention also provides a high sustained-release pesticide, the porous chitosan-azoxystrobin nano sustained-release agent.

[0017] The present invention has the following beneficial effects:

[0018] The present invention prepares porous chitosan nanoparticles to carry azoxystrobin through a low-cost synthesis method to achieve the purpose of nano-formulation and controlled release of azoxystrobin. The porous chitosan nanoparticles with uniform morphology and particle size are prepared at room temperature by interfacial polymerization. The porous chitosan nanoparticles are used to carry the broad-spectrum fungicide azoxystrobin. The use of the nanoparticles in the field can prolong the effective period of the agent, reduce the number of applications, and reduce the amount of application. DETAILED DESCRIPTION

[0019] Now, various exemplary embodiments of the present invention are described in detail. The methods in the examples are conventional methods unless otherwise specified, and the reagents used are conventional commercially available reagents or reagents prepared by conventional methods unless otherwise specified. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, features and embodiments of the present invention.

[0020] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0021] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0022] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0023] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0024] 1. Test methods

[0025] 1. Preparation and characterization of porous chitosan-azoxystrobin nano-sustained release agent

[0026] (1) Weigh 80 ml of paraffin, 1 g of Span-80, and 1 g of Tween-80, stir and mix, and heat and stir at 40°C, 400 r / min for 30 min to obtain an oil phase. Weigh 0.5-1.5 g of azoxystrobin original drug, 10 ml of water, 10 ml of 1% acetic acid, and 0.4 g of chitosan, stir and mix to obtain an aqueous phase. Slowly drop the aqueous phase into the oil phase, mix and emulsify at 500-800 r / min for 30-90 min to obtain an emulsion. Slowly add 2 ml of glutaraldehyde and 2 ml of anhydrous acetic acid to the emulsion, continue heating and stirring at 60°C for 1 h to obtain a porous chitosan-azoxystrobin nano sustained-release agent emulsion. Centrifuge the emulsion at 7500-8500 r for 5 min, and wash alternately with petroleum ether, dichloromethane or chloroform to obtain a porous chitosan-azoxystrobin nano sustained-release agent.

[0027] (2) The prepared porous chitosan-myclobutanil nano sustained-release agent was analyzed for morphology and structure using atomic force microscopy, fluorescence spectrophotometer, Fourier transform infrared spectrometer, X-ray diffractometer, etc.

[0028] 2. Study on the sustained-release performance of porous chitosan-myclobutanil nano sustained-release agent under different conditions.

[0029] (1) Weigh 1.00 g of porous chitosan-azoxystrobin nano sustained-release agent sample and place it in 500 mL of release medium (acetonitrile: water = 20:80, add 0.3% 602#), and stir at 500 rpm. Sampling 0.5 mL at different time intervals, after dilution, filter with 0.22 μm organic filter membrane, and analyze the content of porous chitosan-azoxystrobin nano sustained-release agent by HPLC. At the same time, add 0.5 mL of release medium to the original water environment to maintain a constant volume of the release medium.

[0030] (2) Design different temperature gradients, pH gradients and core-to-wall ratios to test the release performance of the sustained-release agent.

[0031] 2. Results Analysis

[0032] 1. Preparation and characterization of porous chitosan-azoxystrobin nano-sustained release agent

[0033] (1) When the amount of azoxystrobin technical drug added was 1g, the fluorescence intensity of the porous chitosan-azoxystrobin nano sustained-release agent reached a maximum value. When the amount of azoxystrobin technical drug added was increased, the fluorescence intensity did not change significantly. From the perspective of energy consumption, 1g was selected as the optimal amount of raw material added. When the emulsification reaction time of the water phase and the oil phase was 60min and the reaction speed was 600r, the fluorescence intensity reached the maximum value. When the reaction time was increased or the speed was increased, the fluorescence intensity began to decrease. Therefore, the emulsification reaction time of 60min and the speed of 600r were selected as the optimal reaction conditions.

[0034] (2) Stable chitosan-azoxystrobin capsules were prepared under the optimal preparation conditions, and the morphology of the capsules was observed by scanning electron microscopy. The capsules were regular spherical, with smooth and complete outer walls and good dispersion effect.

[0035] 2. Study on the sustained-release performance of porous chitosan-myclobutanil nano sustained-release agent under different conditions.

[0036] The release study of porous chitosan-azoxystrobin nano sustained-release agent under different conditions showed that when the temperature gradually increased, the release rate of the sustained-release agent increased, but the rate of the sustained-release agent was slower than other commercially available preparations. The release curve showed that the capsule sustained-release agent had obvious sustained-release properties.

[0037] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a porous chitosan-azoxystrobin nano sustained-release agent, characterized in that: The following steps are involved: (1) Weigh paraffin, Span-80, and Tween-80, heat and stir to obtain an oil phase; (2) weighing azoxystrobin technical, water, 1% acetic acid, and chitosan, stirring and mixing to obtain an aqueous phase; (3) slowly dripping the water phase into the oil phase, mixing and emulsifying to obtain an emulsion; (4) adding glutaraldehyde and anhydrous acetic acid to the emulsion, and continuing heating and stirring to obtain a porous chitosan-azoxystrobin nano sustained-release agent emulsion; (5) The emulsion is centrifuged and washed alternately with petroleum ether, dichloromethane or chloroform to obtain a porous chitosan-azoxystrobin nano sustained-release agent.

2. The preparation method according to claim 1, characterized in that: The volume mass ratio of the paraffin, Span-80, Tween-80, myclobutanil original drug and chitosan is 80ml:1g:1g:0.5-1.5g:0.4g; the volume ratio of the paraffin, water, 1% acetic acid, glutaraldehyde and anhydrous acetic acid is 80:10:10:2:

2.

3. The preparation method according to claim 2, characterized in that: The volume mass ratio of the paraffin, Span-80, Tween-80, azoxystrobin technical and chitosan is 80ml:1g:1g:1g:0.4g.

4. The preparation method according to claim 1, characterized in that: The heating and stirring in step (1) is 40° C. and 400 r / min for 30 min.

5. The preparation method according to claim 1, characterized in that: The mixed emulsification reaction speed in step (3) is 500-800 r / min, and the reaction time is 30-90 min.

6. The preparation method according to claim 5, characterized in that: The mixed emulsification reaction speed in step (3) is 600 r / min and the reaction time is 60 min.

7. A porous chitosan-azoxystrobin nano sustained-release agent, characterized in that: Prepared by the preparation method according to any one of claims 1 to 6.

8. A high sustained-release pesticide, characterized in that: It comprises the porous chitosan-azoxystrobin nano sustained-release agent as claimed in claim 7.