Cyclodextrin metal organic framework as well as preparation method and application thereof

Abstract

According to the cyclodextrin metal organic framework and the preparation method and application thereof, ultrasonic assistance is replaced with oscillation, the preparation method is low in equipment requirement, small in loss and smaller in energy consumption, the preparation cost is greatly saved, and CD-MOF prepared through the method has the advantages of being small in particle size and uniform in particle size; and the nano-scale size can be easily achieved by additionally adding methanol, so that a foundation is laid for subsequent researches such as drug loading and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of material preparation, and in particular relates to a cyclodextrin metal organic framework and a preparation method and application thereof. Background Art

[0002] In recent years, pesticide controlled-release systems have attracted much attention. Metal-organic frameworks (MOFs) are one of the fastest-growing porous materials and have gradually been used as pesticide carriers to achieve synergistic and controlled-release effects. Cyclodextrin metal-organic frameworks (CD-MOFs) are considered to be a green, renewable new material due to their low material cost and good biocompatibility. They have the potential to become multifunctional pesticide carriers in agricultural applications. Currently, there is relatively little research and development work on related technologies, which is related to the problems of CD-MOF such as the complicated preparation process and easy disintegration in aqueous environments. Therefore, it is of great significance to simplify the preparation process of CD-MOF, achieve efficient loading of pesticides, solve the problems of poor water stability of CD-MOF, and expand its application as a pesticide carrier in rice disease control.

[0003] The main synthesis methods for cyclodextrin metal-organic frameworks currently include the classic vapor diffusion method, solvothermal method, microwave-assisted method, etc. Although these methods can effectively prepare cyclodextrin metal-organic frameworks under laboratory conditions, they also have problems such as difficulty in scalable production, large particle size distribution, high cost, and high energy consumption. Therefore, more green, efficient, environmentally friendly and large-scale production-suitable CD-MOF synthesis processes are needed, which will help promote CD-MOF from laboratory to industrial production and provide a solid foundation for its application in related fields.

[0004] Cyclodextrin materials are widely used in the field of medicine due to their good properties. For example, their good biocompatibility reduces safety risks, can be used to solubilize poorly soluble drugs to improve the bioavailability of drugs, and their unique structure is conducive to achieving controlled release and targeted delivery of drugs. Compared with medicine, pesticides do not have high safety requirements, and too high solubility is not conducive to the efficacy of most pesticides. Therefore, in certain cases, the increase in solubility will have a counterproductive effect. In addition, due to cost reasons, cyclodextrin materials are not widely used in the field of pesticides. Therefore, screening suitable agents is more critical for the application of cyclodextrin materials in the field of pesticides. The present invention has successfully screened pesticides such as pyraclostrobin and achieved their loading on cyclodextrin metal-organic frameworks through a series of exploratory tests, effectively improving the prevention effect, improving its resistance to adverse environments such as ultraviolet radiation, and achieving controlled release. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention aims to provide a cyclodextrin metal organic framework and a preparation method and application thereof, which are specifically achieved through the following technical solutions:

[0006] The first aspect of the present invention provides a method for preparing a cyclodextrin metal organic framework, which comprises the following steps:

[0007] 1) Dissolve γ-CD and KOH in water, shake with a multi-tube shaker or magnetically stir, then filter. Collect the filtrate and add it to methanol to form a milky white solution.

[0008] 2) placing the solution from step 1) in a water bath at 60° C. and stirring with a magnetic stirrer until the solution becomes clear;

[0009] 3) Pour the clarified solution from step 2) into a centrifuge tube, add PEG20000, stir magnetically or shake with a multi-tube shaker until the solution is mixed, then pour the solution into a beaker and place it in a water bath at 60°C for 20 minutes to induce the formation of a white precipitate;

[0010] 4) After the water bath, the precipitation solution was allowed to stand for 2 h, centrifuged at 5000 rpm for 5 min, and the precipitate was collected;

[0011] 5) Wash the precipitate by centrifugation with ethanol 2-3 times, place the product after centrifugal dispersion in a vacuum drying oven, and dry it at 50° C. under vacuum conditions for 1-3 hours to obtain a cyclodextrin metal-organic framework material.

[0012] Furthermore, in step 1), the magnetic stirring time is 10 min, and filtration is performed using a 0.45 μm filter membrane.

[0013] Furthermore, in step 1) and step 3), the shaking time is 5-15 min, and the shaking speed is 1000 rpm-2500 rpm.

[0014] Furthermore, in step 3), methanol is added simultaneously with the addition of PEG2000.

[0015] This invention significantly reduces reaction time compared to the traditional vapor diffusion method by improving the preparation method of cyclodextrin metals. Compared to the recently developed ultrasound-assisted method, the oscillation method replaces the ultrasound-assisted method, requiring less equipment, resulting in lower losses and energy consumption, significantly reducing preparation costs. The CD-MOF prepared by this method has the advantages of small and uniform particle size, and can easily be reduced to nanoscale size by adding methanol, laying the foundation for subsequent research such as drug delivery.

[0016] The second aspect of the present invention provides a cyclodextrin metal organic framework obtained by any of the above preparation methods.

[0017] The third aspect of the present invention provides the use of the cyclodextrin metal organic framework as a pesticide carrier.

[0018] Furthermore, the specific loading method of the cyclodextrin organic framework as a pesticide carrier is:

[0019] 1) Activation of cyclodextrin metal-organic framework material: The cyclodextrin metal-organic framework was added to dichloromethane, allowed to stand for 72 hours, and then centrifuged to remove the precipitate. The precipitate was then dried under vacuum at 50°C for 2 hours to obtain an activated cyclodextrin metal-organic framework material.

[0020] 2) The activated cyclodextrin metal organic framework material was added to ethanol, and the loaded agent was added at the same time. The mixture was stirred at room temperature in the dark for 8 h, and then rotary evaporated to dryness at 40° C. in a magnetic stirrer to complete the loading of the pesticide.

[0021] Furthermore, the pesticide refers to any one of carbendazim, pyraclostrobin or tricyclazole.

[0022] Through a series of exploratory experiments, the present invention successfully screened out pesticides such as pyraclostrobin and achieved their loading on a cyclodextrin metal-organic framework, effectively improving the control effect, improving its resistance to adverse environments such as ultraviolet radiation, and achieving sustained and controlled release. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Flow chart of the preparation process of gamma-cyclodextrin organic framework material by shaking method (A: shaking method 1; B: shaking method 2; C: shaking method 3);

[0024] Figure 2 The particle sizes obtained by different CD-MOF preparation methods;

[0025] Figure 3 The morphological characteristics of CD-MOF obtained by different preparation methods under scanning electron microscopy;

[0026] Figure 4 The particle size of CD-MOF particles prepared with different shaking times;

[0027] Figure 5 The particle size of CD-MOF particles prepared at different oscillation rates;

[0028] Figure 6 Comparison diagram of further optimization of particle size by adding methanol (a: without methanol; b: with methanol; c: particle size data);

[0029] Figure 7 is the drug loading capacity of CD-MOF for different commonly used fungicides;

[0030] Figure 8The effect of pyraclostrobin loading on the stability of CD-MOF in water (from left to right: γ-CD, CD-MOF, CD-MOF loaded with pyraclostrobin a: 6hb: 72h);

[0031] Figure 9 The release characteristics of pyraclostrobin loaded on cyclodextrin metal-organic framework in ethanol solutions of different concentrations;

[0032] Figure 10 The release characteristics of pyraclostrobin loaded on cyclodextrin metal-organic framework in ethanol solutions with different pH values;

[0033] Figure 11 This is the degradation curve of pyraclostrobin loaded on CD-MOF under UV light;

[0034] Figure 12 Indoor activity test of pyraclostrobin loaded on cyclodextrin metal-organic framework against rice sheath blight (a: EC50; b: inhibitory effect of different concentrations of Pyr on mycelial growth; c: inhibitory effect of different concentrations of Pyr@CD-MOF on mycelial growth);

[0035] Figure 13 The control effect of cyclodextrin metal-organic framework-loaded pyraclostrobin on rice sheath blight (a: lesion length and control efficacy; b: artificial inoculation lesions);

[0036] Figure 14 The degradation dynamics of cyclodextrin metal-organic framework-loaded pyraclostrobin in rice plants;

[0037] Figure 15 The control effect of cyclodextrin metal-organic framework loaded with carbendazim on rice panicle rot. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with the accompanying drawings to facilitate a better understanding of the present technical solution.

[0039] Example 1: Preparation and Optimization of Gamma-Cyclodextrin Metal-Organic Framework Materials

[0040] 1.1 The preparation process involved in this embodiment is as follows Figure 1 As shown, the other control processes such as the classical preparation method, ultrasound-assisted method and homogenization method were carried out according to the methods described in the corresponding literature. The corresponding literature is as follows:

[0041] SRA,FRS,F.Hiroyasu,et al.,Metal-organic frameworks from ediblenatural products[J],Angewandte Chemie(Internationaled.in English),2010,49(46):8630-8634.B.Liu,Y.He,L.Han,et al.,Microwave-assisted rapid synthesis ofγ-cyclodextrin metal–organic frameworks for size control and efficient drugloading[J],Crystal Growth&Design,2017,17(4):1654-1660.

[0042] Shen Mofei, Preparation and Antibacterial Application of Cyclodextrin Metal-Organic Framework Composites, PhD Thesis, Zhejiang University, 2022.

[0043] Y.Furukawa,T.Ishiwata,PDKSugikawa,et al.,Nano-and Microsized CubicGel Particles from Cyclodextrin Metal–Organic Frameworks[J],AngewandteChemie,2012,124(42):10718-10721.

[0044] 1.1.1 Oscillation method 1

[0045] Add 648 mg of γ-CD and 256 mg of KOH to a centrifuge tube, dissolve in 20 ml of water, shake for 10 minutes on a multi-tube shaker, pour back into a beaker, and filter with a 0.45 μm filter membrane; add 12 ml of methanol to a new beaker, add the filtered solution to form a milky white solution; place the milky white solution in a water bath at 60°C, and stir magnetically for 15 minutes until the solution becomes clear; add PEG20000 (256 mg) to the clear solution, stir magnetically until the solution is mixed, and place it in a water bath at 60°C again and let it stand for 20 minutes to induce the formation of a white precipitate; after the water bath, let the precipitate solution stand for 2 hours, centrifuge at 5000 rpm for 5 minutes, and wash with ethanol by centrifugation 2-3 times (use 20 ml of ethanol for the first time and 12 ml of ethanol thereafter); place the product after centrifugal dispersion in a vacuum drying oven and dry it at 50°C for several hours under vacuum conditions.

[0046] 1.1.2 Oscillation method 2

[0047] Dissolve 648 mg of γ-CD and 256 mg of KOH in 20 ml of water, stir magnetically for 10 minutes, and filter through a 0.45 μm filter membrane. Add 12 ml of methanol to a new beaker and add the filtered solution to form a milky white solution. Pour the solution into a centrifuge tube and shake on a multitube shaker for 10 minutes before returning it to the beaker. Place the solution in a water bath at 60°C and stir magnetically for 15 minutes until the solution becomes clear. Add PEG20000 (256 mg) to the clear solution and stir magnetically until the solution is mixed. Place the solution in a water bath at 60°C again and let it stand for 20 minutes to induce the formation of a white precipitate. After the water bath, let the precipitate stand for 2 hours and then wash and dry as described in 1.1.1.

[0048] 1.1.3 Oscillation method 3

[0049] Dissolve 648 mg of γ-CD and 256 mg of KOH in 20 ml of water, stir magnetically for 10 minutes, and filter with a 0.45 μm filter membrane; add 12 ml of methanol to a new beaker and add the filtered solution to form a milky white solution; place the solution in a water bath at 60°C and stir magnetically for 15 minutes until the solution becomes clear; pour the clear solution into a centrifuge tube, add PEG20000 (256 mg), and shake on a multi-tube shaker for 10 minutes; pour the solution into a beaker and place it in a water bath at 60°C again for 20 minutes to induce the formation of a white precipitate; after the water bath, let the precipitate solution stand for 2 hours, centrifuge at 5000 rpm for 5 minutes, and wash and dry according to the method described in 1.1.1.

[0050] 1.2 Comparative analysis of CD-MOFs prepared by different methods

[0051] The particle sizes of CD-MOF obtained by different preparation methods are as follows Figure 2 As shown, the resulting particle sizes ranged from 500 to 1200 nm, significantly smaller than those reported in most literature. The three oscillation methods produced the smallest CD-MOF particle sizes, followed by the ultrasound-assisted method, the homogenization method, and the basic preparation method. The oscillation method had the smallest standard deviation among the various methods, demonstrating good reproducibility. Therefore, the oscillation method was the most ideal CD-MOF preparation method in this study, with oscillation method 3 being the most optimal, achieving particle sizes less than 500 nm.

[0052] The morphological characteristics of CD-MOF synthesized by different preparation methods are as follows: Figure 3As shown, all methods obtained typical cubic crystals. The crystals obtained by the basic preparation method were irregular in shape and uneven in size. The ultrasonic-assisted method produced more broken particles, which may be related to the crystal breakage under ultrasound. The cracks caused by the crystal breakage can also be clearly observed. The crystals obtained by the homogenization method also have the problem of uneven size and a large number of broken particles. The CD-MOF crystals obtained by the three oscillation methods are obviously more regular in shape and uniform in size. Among them, the crystal edges obtained by oscillation method 1 are clearer, and the crystals obtained by oscillation method 3 have good consistency in size.

[0053] 1.3 Optimization of preparation process

[0054] 1.3.1 Optimization of oscillation time

[0055] The particle size data of CD-MOF particles prepared at different shaking times are as follows: Figure 4 As shown in the figure, as the shaking time increases from 5 minutes to 15 minutes, the particle size shows a significant downward trend. When the shaking time is 10 minutes and 15 minutes, the particle size is less than 500nm. Although the particle size of 15 minutes is smaller than that of 10 minutes, considering that the size difference is not obvious and does not reach a significant level, 10 minutes is determined to be the optimal shaking time based on the convenience of operation and cost.

[0056] 1.3.2 Optimization of oscillation rate

[0057] The present invention tested the particle size of CD-MOF prepared at oscillation speeds of 1000 rpm, 2000 rpm and 2500 rpm, and the results were as follows: Figure 5 As shown in the figure, the experimental results show that at an oscillation speed of 1000 rpm, the particle size is approximately 600 nm. As the oscillation speed increases, the particle size shows a clear downward trend. At an oscillation speed of 2500 rpm, the particle size can reach below 400 nm and is relatively stable. However, 2500 rpm is almost the limit of the equipment, and if the oscillation speed is further increased, the sample heating phenomenon becomes increasingly serious, increasing the probability of synthesis failure. Therefore, 2500 rpm is determined to be the optimal oscillation speed.

[0058] 1.3.3 Further optimization of CD-MOF particle size

[0059] According to the oscillation-assisted method, the particle size of CD-MOF can be controlled to 400-500nm. Taking into account the advantage of the small size effect, the present invention adds 1.5 times the volume of methanol relative to the original solution on this basis, successfully reducing the particle size to below 200nm (such as Figure 6 As shown in the electron microscope photograph, the particle size is significantly reduced after adding methanol, while the crystals can still maintain the basic cubic shape.

[0060] 1.4 Summary of the preparation process of gamma-cyclodextrin metal-organic framework materials by oscillation method

[0061] Through a series of research and development, the present invention has determined that the oscillation method is the optimal CD-MOF synthesis method. At the same time, the optimal oscillation time and oscillation rate are obtained through experiments, and the particle size is further optimized by adding methanol.

[0062] The method involves dissolving 648 mg of γ-CD and 256 mg of KOH in 20 ml of water, stirring magnetically for 10 minutes, and then filtering through a 0.45 μm filter membrane. 12 ml of methanol is added to a new beaker, followed by the filtered solution, to form a milky white solution. The solution is placed in a 60°C water bath and stirred magnetically for 15 minutes until the solution becomes clear. The clarified solution is poured into a centrifuge tube, 256 mg of PEG20000 is added, and the solution is shaken for 10 minutes using a multi-tube shaker. The solution is then poured into a beaker and placed in a 60°C water bath again, allowing it to stand for 20 minutes to induce the formation of a white precipitate. After the water bath, the precipitate is allowed to stand for 2 hours and then centrifuged at 5000 rpm for 5 minutes. To further reduce the particle size to the nanometer level, 32 ml of methanol is added simultaneously with the addition of PEG2000 to further reduce the particle size.

[0063] This invention focuses on improving the synthesis process of cyclodextrin metal-organic framework (CD-MOF), aiming to solve many problems of existing synthesis methods, such as complicated procedures and long time consumption, so as to promote CD-MOF from laboratory to industrial production.

[0064] Compared to the classic vapor diffusion method, the improved preparation process of this invention significantly reduces reaction time. While the vapor diffusion method is effective for synthesizing CD-MOFs in laboratory preparation, its long reaction time severely limits its efficiency in large-scale production. Shortening reaction time not only improves production efficiency but also reduces equipment time and labor investment, thereby lowering production costs. This is of great significance for industrial large-scale production.

[0065] In terms of energy consumption and equipment requirements, the present invention adopts the oscillation method instead of the ultrasound-assisted method, which has obvious advantages. Although the ultrasound-assisted method is an emerging synthesis method, it has high equipment requirements, large equipment losses and high energy consumption. The oscillation method, on the other hand, has simple equipment, is easy to operate, has low equipment losses and lower energy consumption. This makes the synthesis process more environmentally friendly and in line with the concept of sustainable development. It also reduces the initial equipment investment cost and long-term operating cost of industrial production, and improves the feasibility and cost-effectiveness of the process.

[0066] Particle size is crucial to the performance and application of CD-MOF. The CD-MOF prepared by the method of the present invention has the advantages of small and uniform particle size, and can also reach nanoscale size by additionally adding methanol. Small and uniform CD-MOF has unique advantages in applications such as drug delivery. In the field of pharmaceutical research and development, nanoscale CD-MOF as a drug carrier can increase drug loading and encapsulation efficiency, enhance drug stability, and improve drug release properties, achieving precise drug delivery and controlled release, improving drug efficacy and reducing toxic side effects, providing a higher-quality material foundation for drug research and development.

[0067] Example 2: Loading of common fungicides on cyclodextrin metal-organic frameworks

[0068] 2.1 Loading Method

[0069] The CD-MOF material prepared according to the method of Example 1 was added with 20 ml of dichloromethane, allowed to stand for 72 hours, centrifuged to remove the precipitate, and dried under vacuum at 50°C for 2 hours. 0.5 g of the activated CD-MOF material was weighed and added to 25 ml of ethanol. At the same time, 0.2 g of the reagent was weighed. The mixture was stirred at room temperature in the dark for 8 hours, then placed in a magnetic stirrer at 40°C and rotary evaporated to dryness at level 2.

[0070] 2.2 Loading of different fungicides on CD-MOF

[0071] The loading of common fungicides on CD-MOF was successfully achieved by room temperature stirring method, and the loading rate was as follows: Figure 7 As shown in the figure, the highest loading rates for carbendazim, pyraclostrobin, and tricyclazole were achieved, reaching 27.9%, 23.3%, and 19.9%, respectively. Tebuconazole, trifloxystrobin, and azoxystrobin were next, with loading rates all below 20%. Prochloraz and jinggangmycin had the lowest loading rates, at approximately 6% and 3%, respectively. This suggests that CD-MOF exhibits significant selectivity for the type of pesticide loaded, achieving high loading rates only for some pesticides, such as carbendazim, pyraclostrobin, and tricyclazole.

[0072] Example 3: Effect of Cyclodextrin Metal-Organic Framework Loading on the Performance of Pyraclostrobin

[0073] 3.1 Effect of pyraclostrobin loading on the stability of CD-MOF in water

[0074] As a pesticide carrier, CD-MOF is too water-soluble, which is not conducive to achieving sustained and controlled release, nor is it conducive to the effectiveness of the drug. Our research found that CD-MOF loaded with pyraclostrobin is almost insoluble in water and is suspended in water. Figure 8After 6 hours of stirring and rest, the pyraclostrobin-loaded CD-MOF remained suspended, but the γ-CD had completely dissolved, and the unloaded CD-MOF had also largely dissolved. After 72 hours of rest, the unloaded CD-MOF had almost completely dissolved, while the pyraclostrobin-loaded CD-MOF mostly precipitated at the bottom of the beaker, with some suspended and the majority remaining undissolved.

[0075] 3.2 Release patterns of pyraclostrobin loaded on CD-MOF in ethanol solutions of different concentrations

[0076] After using cyclodextrin metal organic framework material to load pyraclostrobin, its release pattern in ethanol solutions of different concentrations was studied. The results are as follows Figure 9 shown.

[0077] from Figure 9 It can be seen that Pyr@CD-MOF is not easily released in 20% ethanol, and the maximum release amount after 90 hours is less than 10%. When the ethanol content is increased to above 40%, the maximum release amount of pyraclostrobin can increase to more than 50%, and the release amount increases with the increase of ethanol content, reaching about 60% in 80% ethanol solution.

[0078] 3.3 Effect of pH on the release of pyraclostrobin loaded on CD-MOF

[0079] After pyraclostrobin was loaded on CD-MOF, its release pattern in 50% ethanol solution with different pH values ​​was studied. Figure 10 Overall, pH has little effect on the release of Pyr@CD-MOF within the pH range of 5.0-8.0, with release trends remaining roughly consistent. Release at pH 5.0 and 7.0 is nearly identical, reaching approximately 65%. However, at pH 8.0, pyraclostrobin release is slower, reaching only approximately 60%, and its maximum release is also lower than the previous two. This may be due to the CD-MOF's greater stability in weakly alkaline environments.

[0080] 3.4 Study on the photostability of pyraclostrobin loaded on CD-MOF

[0081] The present invention detects the degradation curve of pyraclostrobin under ultraviolet light, and the results are as follows Figure 11 As shown in Figure 2, after loading onto CD-MOF, the degradation rate of pyraclostrobin under UV radiation significantly slowed. After 9 hours of UV radiation, unloaded pyraclostrobin was no longer detectable, while pyraclostrobin loaded onto CD-MOF became undetectable after 13 hours.

[0082] 3.5 Summary

[0083] Loading pyraclostrobin can greatly improve the stability of CD-MOF in water. The release rate of the loaded pyraclostrobin in water is low, but the release rate is greatly accelerated after adding ethanol, and the release amount increases with the increase of ethanol content. The effect of pH on the release of pyraclostrobin loaded in CD-MOF is relatively limited. Compared with slightly acidic and neutral environments, its release amount is slower in a slightly alkaline environment (pH = 8.0) and the maximum release amount is also smaller. This may be related to the fact that CD-MOF is more stable in a weak alkaline environment. UV decomposition tests show that loading on CD-MOF can greatly improve the UV radiation stability of pyraclostrobin.

[0084] After loading pyraclostrobin, the CD-MOF significantly improved its stability in water. This allows the composite material to be more stable in the water environment of rice cultivation, ensuring the effective efficacy of the fungicide. The release rate of loaded pyraclostrobin in water is low, but ethanol significantly accelerates its release rate, and the release rate increases with increasing ethanol content. This property provides the possibility of tailoring drug release to meet specific needs in practical applications. For example, when rapid drug efficacy is required, this can be achieved by adding an appropriate amount of ethanol. The pH has a limited effect on the release of pyraclostrobin from CD-MOF, but the release rate is lower and slower in a slightly alkaline environment (pH = 8.0). This is speculated to be related to the CD-MOF's greater stability in weakly alkaline environments. Therefore, the impact of this factor on drug efficacy in different acid-base environments should be considered during rice cultivation. UV decomposition experiments show that CD-MOF significantly improves the UV stability of pyraclostrobin, which is particularly critical in rice cultivation environments, where strong sunlight radiation shortens the effective life of the fungicide. Loaded pyraclostrobin can better cope with this challenge.

[0085] Overall, the use of CD-MOF-loaded pyraclostrobin meets the unique fungicide requirements of rice in many aspects, providing valuable research directions for developing more efficient, safe, and economical rice fungicide formulations. Further research is needed to investigate the effectiveness of this composite material in actual rice fields, as well as its long-term effects on aquatic organisms and the ecological environment, to advance its application from laboratory research to widespread agricultural production practice.

[0086] Example 4: Comparison of the effect of pyraclostrobin on the indoor antibacterial activity of CD-MOF

[0087] The indoor toxicity of pyraclostrobin loaded on cyclodextrin metal organic framework to rice sheath blight pathogen was tested by colony growth inhibition method. Figure 12 As shown. Pyr EC 50 is 0.503 μg / ml, while the EC of Pyr@CD-MOF 50The difference between the two is only 0.05 μg / ml. Therefore, compared with the unloaded pyraclostrobin, the EC of pyraclostrobin loaded on the cyclodextrin metal organic framework material is 50 Has decreased.

[0088] Example 5: CD-MOF loading can enhance the control effect of pyraclostrobin on rice sheath blight

[0089] This example measured the control effect of cyclodextrin metal organic framework loaded with pyraclostrobin on rice sheath blight. The results are as follows Figure 13 The control lesion had the longest length, with an average length of 10.4 cm, followed by the lesion with only CD-MOF at 7.4 cm, the lesion with pyraclostrobin at only 4.5 cm, and the lesion with CD-MOF loaded with pyraclostrobin at the shortest length, only 3.1 cm ( Figure 13 a), the length of lesions in each treatment was significantly different ( Figure 13 b). Test results showed that cyclodextrin metal-organic frameworks (CD-MOFs) have a certain inhibitory effect on rice sheath blight. Since cyclodextrin itself is non-toxic, there are currently no reports of CD-MOFs inhibiting plant diseases. This may be because cyclodextrins regulate the physiological metabolism of rice plants, inducing systemic resistance in rice and increasing the activity of disease-resistance-related enzymes in the rice body, such as peroxidase and polyphenol oxidase. This enhances rice resistance to sheath blight by affecting the microbial community structure in the soil, increasing the number of microorganisms beneficial to rice, and inhibiting the growth of the sheath blight pathogen. At the same dosage level, pyraclostrobin loaded on the cyclodextrin metal-organic framework was significantly more effective than pyraclostrobin alone, with a synergistic coefficient of 0.48, demonstrating a significant synergistic effect.

[0090] Example 6: Effect of cyclodextrin metal-organic frameworks on the degradation dynamics of pyraclostrobin loaded therein

[0091] By collecting samples on the day of spraying and 1, 3, 6, 15, 20, and 25 days later, the degradation dynamics of unloaded pyraclostrobin and pyraclostrobin loaded on CD-MOF in rice were detected. The results are as follows: Figure 14As shown in the results, it was found that pyraclostrobin residues were still detectable within the first 20 days after application, but no residues were detected after 25 days. In the unloaded state, the residual amount of pyraclostrobin after 20 days of application was only 1.43-3.19% of the sprayed amount, with a first-order kinetic equation of y = 0.8266e-0.184x (R2 = 0.9543) and a half-life of 3.72 days. However, the residual amount of pyraclostrobin loaded on CD-MOF after 20 days of application was 3.65-5.39% of the sprayed amount, with a first-order kinetic equation of y = 0.9539e-0.136x (R2 = 0.9468), and a half-life of 5.09 days.

[0092] This suggests that cyclodextrin can effectively extend the residual effect of pyraclostrobin, suggesting that the mechanism by which CD-MOF enhances the efficacy of the agent may be related to its ability to slow degradation and extend its residual effect. Considering that solar radiation, such as ultraviolet rays, may be the primary cause of field agent decomposition, the specific mechanism may be related to its enhanced UV stability.

[0093] Example 7: Synergistic effect of cyclodextrin metal-organic framework loading on carbendazim in controlling rice ear rot

[0094] This example studies the control effect of cyclodextrin metal organic framework material loaded with carbendazim on rice ear rot. Figure 15 As shown, CD-MOF alone has a very limited control effect on rice ear rot, only 9.62%, while carbendazim has a control effect of 52.8%. However, CD-MOF loaded with the same amount of carbendazim significantly improves its control effect against ear rot, reaching 64.7%, with a synergistic coefficient of +7.31, demonstrating a significant synergistic effect. Therefore, cyclodextrin metal-organic framework loading significantly enhances the synergistic effect of carbendazim on rice ear rot.

Claims

1. A method for preparing a cyclodextrin metal organic framework, characterized in that: The preparation method comprises the following steps: 1) Dissolve γ-CD and KOH in water, shake with a multi-tube shaker or magnetically stir, then filter. Collect the filtrate and add it to methanol to form a milky white solution. 2) Place the solution from step 1) in a water bath at 60°C and stir magnetically until the solution becomes clear; 3) Pour the clarified solution from step 2) into a centrifuge tube, add PEG 20000, and stir magnetically or shake with a multitube shaker until the solution is thoroughly mixed. Pour the solution into a beaker and place it in a water bath at 60°C for 20 minutes to induce the formation of a white precipitate. 4) After the water bath, the precipitation solution was allowed to stand for 2 hours, centrifuged at 5000 rpm for 5 minutes, and the precipitate was collected; 5) Wash the precipitate by centrifugation with ethanol 2-3 times, place the product after centrifugal dispersion in a vacuum drying oven, and dry it at 50° C. under vacuum conditions for 1-3 hours to obtain a cyclodextrin metal-organic framework material.

2. The method for preparing a cyclodextrin metal organic framework according to claim 1, wherein In step 1), the magnetic stirring time is 10 min, and the solution is filtered using a 0.45 μm filter membrane.

3. The method for preparing a cyclodextrin metal organic framework according to claim 1, wherein The shaking time in step 1) and step 3) is 5-15 minutes, and the shaking speed is 1000 rpm-2500 rpm.

4. The method for preparing a cyclodextrin metal organic framework according to claim 1, wherein In step 3), methanol is added simultaneously with the addition of PEG2000.

5. A cyclodextrin metal-organic framework prepared by the preparation method according to any one of claims 1 to 4.

6. Use of the cyclodextrin metal organic framework as claimed in claim 5 as a pesticide carrier.

7. The use according to claim 6, characterized in that The specific loading method of cyclodextrin organic framework as pesticide carrier is: 1) Activation of CD-MOF: Add CD-MOF to dichloromethane, let it stand for 72 hours, then centrifuge to remove the precipitate, and dry it in a vacuum at 50°C for 2 hours to obtain the activated CD-MOF. 2) Take the activated cyclodextrin metal organic framework material, add it to ethanol, add the loaded agent at the same time, stir at room temperature in the dark for 8 hours, and rotary evaporate to dryness in a magnetic stirrer at 40°C to complete the loading of the pesticide.

8. The use according to claim 6 or 7, characterized in that The pesticide refers to any one of carbendazim, pyraclostrobin or tricyclazole.

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