Preparation method and application of ZnO-ZIF-8 composite material loaded with honokiol

Abstract

The invention discloses a preparation method and application of a ZnO-ZIF-8 composite material loaded with honokiol, belonging to the technical field of agricultural plant protection. The method comprises the following steps: (1) mixing 2-methylimidazole and N,N-dimethylformamide to obtain a preheating solution; preparing a zinc oxide suspension from nano zinc oxide; (2) preparing a mixed solution from honokiol; (3) preparing a sodium alginate solution from sodium alginate, and then heating the sodium alginate solution, the mixed solution, the preheating solution and the zinc oxide suspension for reaction for 2 hours, collecting the precipitate by centrifugation and drying to obtain a ZnO-ZIF-8 composite material loaded with honokiol. The composite material prepared by the invention solves the problems of low honokiol loading rate and poor control effect under acidic conditions, and the prepared composite material can reduce the harm to soil or animals and plants.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural plant protection, and in particular to a preparation method and application of a ZnO-ZIF-8 composite material loaded with honokiol. Background Art

[0002] Ralstonia solanacearum is an important bacterial plant pathogen with a wide distribution range, with more than 50 families and more than 200 species of hosts, including potatoes, peanuts, tobacco, papaya, tomatoes, etc. It is reported that the pathogen attaches to the roots of plants, then gathers on the xylem blood vessels, over-secretes cell wall degrading enzymes and extracellular polysaccharides to block the vascular system, and eventually leads to the death of the host. In addition, the bacterial wilt pathogen can adapt to acidic conditions. When the soil pH is lower than 5.5, the outbreak rate of bacterial wilt disease is greatly increased. Therefore, the development of a drug that can effectively control bacterial wilt disease under acidic conditions is of great significance in agricultural production.

[0003] Zinc oxide is harmful to microorganisms and has been widely used as a fungicide. When the particle size is reduced to nanometer size, nano zinc oxide can interact with the bacterial surface or enter the bacteria, and exhibit a unique bactericidal mechanism, resulting in light-induced release of reactive oxygen species (ROS), formation of hydrogen peroxide and release of zinc ions to cause mechanical damage to bacteria, thereby achieving the purpose of sterilization. In addition, in agriculture, zinc oxide can be used as an enhancer to enhance the absorption of macronutrient fertilizers by plants. However, when zinc oxide is used as a fungicide, if it is applied to crops in large quantities, it will not only cause excessive trace elements in the soil, but also cause heavy metal pollution in the soil, thereby causing enrichment and endangering human or animal health. If zinc-containing water is used to irrigate crops, it will also cause uneven plant emergence or short plants, and at the same time make the soil inactive, reduce the number of bacteria, weaken the action of microorganisms in the soil, and cause zinc pollution. Therefore, it is usually necessary to load zinc oxide with agents to reduce its content while improving the bactericidal performance. Honokiol is an active ingredient extracted and separated from the traditional Chinese medicine Magnolia officinalis. It has pharmacological properties such as antibacterial, antioxidant, anti-inflammatory, anti-tumor and neuroprotective. Its antibacterial mechanism includes damage to bacterial cell membranes and cell walls, increased cell membrane permeability or cell wall dissolution, leading to leakage of cell components, structural damage and changes in bacterial cell morphology. Honokiol has a bactericidal effect. It has a good bactericidal effect within a high concentration range in the laboratory, but its actual bactericidal effect is significantly reduced in the field. If it is directly loaded on zinc oxide nanoparticles, the loading rate is low, and the virus prevention and control effect for actual agricultural production is low.

[0004] Although both magnolia officinalis and zinc oxide have certain preventive and therapeutic effects on bacterial wilt, considering the characteristics of bacterial wilt that is prone to break out under acidic conditions, the composite material obtained by directly loading magnolia officinalis on zinc oxide not only has a low loading rate, but also has poor effect on preventing and controlling bacterial wilt under acidic conditions. Therefore, there is an urgent need for a composite material loaded with magnolia officinalis to prevent and control bacterial wilt under acidic conditions. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a preparation method and application of a ZnO-ZIF-8 composite material loaded with magnolol, so as to solve the problems of low loading rate of magnolol and poor control effect under acidic conditions, and at the same time, the prepared composite material can reduce the harm to soil or animals and plants.

[0006] The present invention solves the above technical problems by the following technical means:

[0007] A method for preparing a ZnO-ZIF-8 composite material loaded with honokiol, the method comprising the following steps:

[0008] (1) mixing 2-methylimidazole and N,N-dimethylformamide, stirring and dissolving, and then preheating to obtain a preheated solution for standby use; mixing nano zinc oxide with water to prepare a zinc oxide suspension for standby use;

[0009] (2) mixing honokiol with hexadecyltrimethylammonium bromide, N,N-dimethylformamide, and polyethylene glycol to prepare a mixed solution for standby use;

[0010] (3) mixing sodium alginate with water to prepare a sodium alginate solution with a concentration of 0.5-1 g / ml, then mixing the sodium alginate solution with the mixed solution, adjusting the pH to 7.5-8, adding N-hydroxysuccinimide, stirring for 5-10 minutes, adding the preheated solution and zinc oxide suspension, heating the reaction for 2 hours, and collecting the precipitate by centrifugation;

[0011] (4) Mixing the obtained precipitate with water, adjusting the pH to 8-9, stirring for 5-10 minutes and then standing for 10-12 hours, collecting the precipitate by centrifugation, and drying to obtain a ZnO-ZIF-8 composite material loaded with honokiol.

[0012] The invention adopts a solvent method to prepare a ZnO-ZIF-8 composite material loaded with honokiol, but the honokiol loading rate is low when the composite material is prepared by a common solvent method. Therefore, the invention prepares a pH-sensitive hydrogel containing honokiol by mixing a sodium alginate solution with a mixed solution mixed with honokiol and polyethylene glycol, and then reacting with N-hydroxysuccinimide. Then, the pore size of the synthesized ZnO-ZIF-8 particles is blocked in advance during the heating reaction process, thereby preventing excess organic solvent from entering the particle pore size and affecting the specific surface area of ​​the composite material. Subsequently, the pH is adjusted to alkaline-degrade the gel during the standing process, thereby retaining the honokiol in the pore size of the ZnO-ZIF-8 particles and improving the loading rate.

[0013] At the same time, since the outbreak condition of Ralstonia solanacearum is acidic, and when the pH value is less than 5.5, the outbreak rate is greatly improved, and the composite material prepared by the present invention will dissociate under acidic conditions, releasing the encapsulated honokiol and nano zinc oxide, which has the effect of sustained release and sterilization, prolongs the sterilization time, and improves the sterilization effect.

[0014] Furthermore, the mass ratio of the 2-methylimidazole to N,N-dimethylformamide is 1:100.

[0015] Furthermore, the mass concentration of zinc oxide in the zinc oxide suspension is 0.4%.

[0016] Furthermore, the mass ratio of honokiol, hexadecyltrimethylammonium bromide, N,N-dimethylformamide and polyethylene glycol is 100:90:15:(8-12).

[0017] Furthermore, the mass ratio of the sodium alginate to N-hydroxysuccinimide is 1:(0.05-0.1).

[0018] Furthermore, the temperature of the preheated solution is 65-75°C.

[0019] Furthermore, the heating reaction in step (3) is carried out at 70-75° C. for 2 h.

[0020] Furthermore, the mass ratio of the sodium alginate solution: the mixed solution: the preheated solution: the zinc oxide suspension is 1:2:1:1.

[0021] The invention also discloses a prepared ZnO-ZIF-8 composite material loaded with honokiol for preventing and treating bacterial wilt, especially for preventing and treating Ralstonia solanacearum.

[0022] Beneficial effects:

[0023] The present invention prepares a nanocomposite material ZnO-ZIF-8 loaded with honokiol and having a significant effect for treating tobacco bacterial wilt. At the same time, the problems of low honokiol loading and poor treatment effect under acidic conditions are solved. The composite material can reduce the abuse of heavy metal ions in agriculture, can not only reduce the metal content but also improve the bactericidal effect, reduce the harm to plants and soil, and has good application prospects in agriculture. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 : TEM image of composite materials;

[0025] Figure 2 : SEM images of composite materials;

[0026] Figure 3 : Honokiol growth curve determination diagram;

[0027] Figure 4 : Example 1 growth curve determination diagram;

[0028] Figure 5 : Comparative Example 1 growth curve determination diagram;

[0029] Figure 6 : Comparative Example 2 growth curve determination diagram;

[0030] Figure 7 : Comparative Example 3 growth curve determination diagram;

[0031] Figure 8 : Example 1 in vitro antibacterial plate diagram;

[0032] Fig. 9 : In vitro antibacterial plate diagram of comparative example 3. DETAILED DESCRIPTION

[0033] The present invention will be described in detail below with reference to specific embodiments and accompanying drawings:

[0034] The sodium alginate selected in the present invention has a viscosity of 200-210 mPa·s at 25°C.

[0035] Example 1: Preparation of ZnO-ZIF-8 composite material loaded with honokiol

[0036] (1) mixing 1 g of 2-methylimidazole and 100 g of N,N-dimethylformamide, stirring and dissolving, and then preheating to obtain a preheated solution at 70° C., which is kept warm for later use; mixing nano zinc oxide with a particle size of 100-200 nm with water to prepare a zinc oxide suspension with a mass concentration of 0.4%, which is set aside;

[0037] (2) 100 g of honokiol was mixed with 90 g of hexadecyltrimethylammonium bromide, 15 g of N,N-dimethylformamide, and 8 g of polyethylene glycol to prepare a mixed solution for standby use;

[0038] (3) Sodium alginate was mixed with water to prepare a sodium alginate solution with a mass concentration of 1 g / ml, and then the sodium alginate solution and the mixed solution were mixed at a mass ratio of 1:2, and N-hydroxysuccinimide was added after adjusting the pH to 7.5, wherein the mass ratio of sodium alginate to N-hydroxysuccinimide was 1:0.05, and after stirring for 10 minutes, a preheated solution and a zinc oxide suspension of the same mass as the sodium alginate solution were added respectively, and the mixture was heated at 70°C for 2 hours, and the precipitate was collected by centrifugation;

[0039] (4) The obtained precipitate was mixed with water, the pH was adjusted to 8, the mixture was stirred for 5 min and then allowed to stand for 12 h, the precipitate was collected by centrifugation, and dried at 60° C. overnight to obtain a ZnO-ZIF-8 composite material loaded with honokiol.

[0040] The prepared ZnO-ZIF-8 composite material loaded with honokiol was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Figure 1-Figure 2 As shown, analysis Figure 1-Figure 2 The results show that:

[0041] From the TEM and SEM images of the composite material, it can be seen that the composite material is an irregular sphere, divided into a core-shell structure, with the core inside and the outer layer being a shell wrapped outside. The size of the composite material is between 200-300nm, the inner layer is composed of zinc oxide balls with a relatively thick thickness, and the outer shell is wrapped by ZIF-8 and loaded with magnolia bark phenol.

[0042] Example 2: Preparation of ZnO-ZIF-8 composite material loaded with honokiol

[0043] (1) Mix 1 g of 2-methylimidazole and 100 g of N,N-dimethylformamide, stir and dissolve, and then preheat to obtain a preheated solution at 75° C., which is kept warm for later use; mix nano zinc oxide with water to prepare a zinc oxide suspension with a mass concentration of 0.4%, which is set aside;

[0044] (2) 100 g of honokiol was mixed with 90 g of hexadecyltrimethylammonium bromide, 15 g of N,N-dimethylformamide, and 10 g of polyethylene glycol to prepare a mixed solution for standby use;

[0045] (3) Sodium alginate was mixed with water to prepare a sodium alginate solution with a mass concentration of 1 g / ml, and then the sodium alginate solution and the mixed solution were mixed at a mass ratio of 1:2, and N-hydroxysuccinimide was added after adjusting the pH to 8, wherein the mass ratio of sodium alginate to N-hydroxysuccinimide was 1:0.08, and after stirring for 10 minutes, a preheated solution and a zinc oxide suspension of the same mass as the sodium alginate solution were added respectively, and the mixture was heated at 75°C for 2 hours, and the precipitate was collected by centrifugation;

[0046] (4) The obtained precipitate was mixed with water, the pH was adjusted to 8.5, the mixture was stirred for 5 min and then allowed to stand for 12 h, the precipitate was collected by centrifugation, and dried at 60° C. overnight to obtain a ZnO-ZIF-8 composite material loaded with honokiol.

[0047] Example 3: Preparation of ZnO-ZIF-8 composite material loaded with honokiol

[0048] (1) Mix 1 g of 2-methylimidazole and 100 g of N,N-dimethylformamide, stir and dissolve, and then preheat to obtain a preheated solution at 65° C., which is kept warm for later use; mix nano zinc oxide with water to prepare a zinc oxide suspension with a mass concentration of 0.4%, which is set aside;

[0049] (2) 100 g of honokiol was mixed with 90 g of hexadecyltrimethylammonium bromide, 15 g of N,N-dimethylformamide, and 12 g of polyethylene glycol to prepare a mixed solution for standby use;

[0050] (3) Sodium alginate was mixed with water to prepare a sodium alginate solution with a mass concentration of 0.5 g / ml, and then the sodium alginate solution and the mixed solution were mixed at a mass ratio of 1:2, and N-hydroxysuccinimide was added after adjusting the pH to 8, wherein the mass ratio of sodium alginate to N-hydroxysuccinimide was 1:0.1, and after stirring for 5 minutes, a preheated solution and a zinc oxide suspension of the same mass as the sodium alginate solution were added respectively, and the reaction was heated at 75° C. for 2 hours, and the precipitate was collected by centrifugation;

[0051] (4) The obtained precipitate was mixed with water, the pH was adjusted to 9, the mixture was stirred for 10 min and then allowed to stand for 10 h, the precipitate was collected by centrifugation, and dried at 60° C. overnight to obtain a ZnO-ZIF-8 composite material loaded with honokiol.

[0052] Comparative Example 1:

[0053] This comparative example is in contrast to Example 1, and the difference is that the composite material is directly prepared by a solvent method. The specific preparation method is as follows:

[0054] (1) Mix 1 g of 2-methylimidazole and 100 g of N,N-dimethylformamide, stir and dissolve, and then preheat to obtain a preheated solution at 70° C., which is kept warm for later use; mix nano zinc oxide with water to prepare a zinc oxide suspension with a mass concentration of 0.4%, which is set aside;

[0055] (2) 100 g of honokiol was mixed with 90 g of hexadecyltrimethylammonium bromide and 15 g of N,N-dimethylformamide to prepare a mixed solution for standby use;

[0056] (3) The mixed solution, the preheated solution and the zinc oxide suspension were mixed in a mass ratio of 2:1:1, heated at 70°C for 2 h, the precipitate was collected by centrifugation, and dried at 60°C overnight to obtain a ZnO-ZIF-8 composite material loaded with magnolol.

[0057] Comparative Example 2:

[0058] This comparative example is in contrast to Example 1, the difference being that the composite material is prepared directly using sodium alginate gel without using polyethylene glycol and N-hydroxysuccinimide. The specific preparation method is as follows:

[0059] (1) Mix 1 g of 2-methylimidazole and 100 g of N,N-dimethylformamide, stir and dissolve, and then preheat to obtain a preheated solution at 70° C., which is kept warm for later use; mix nano zinc oxide with water to prepare a zinc oxide suspension with a mass concentration of 0.4%, which is set aside;

[0060] (2) 100 g of honokiol was mixed with 90 g of hexadecyltrimethylammonium bromide and 15 g of N,N-dimethylformamide to prepare a mixed solution for standby use;

[0061] (3) Sodium alginate was mixed with water to prepare a sodium alginate solution with a mass concentration of 1 g / ml, and then the sodium alginate solution and the mixed solution were mixed at a mass ratio of 1:2, and after stirring for 10 minutes, the preheated solution and zinc oxide suspension with the same mass as the sodium alginate solution were added respectively, and the mixture was heated at 70° C. for 2 hours, and the precipitate was collected by centrifugation;

[0062] (4) The obtained precipitate was mixed with water, the pH was adjusted to 8, the mixture was stirred for 5 min and then allowed to stand for 12 h, the precipitate was collected by centrifugation, and dried at 60° C. overnight to obtain a ZnO-ZIF-8 composite material loaded with honokiol.

[0063] Comparative Example 3:

[0064] This comparative example is in contrast to Example 1, the difference being that no alkaline degradation step is performed. The specific preparation method is as follows:

[0065] (1) Mix 1 g of 2-methylimidazole and 100 g of N,N-dimethylformamide, stir and dissolve, and then preheat to obtain a preheated solution at 70° C., which is kept warm for later use; mix nano zinc oxide with water to prepare a zinc oxide suspension with a mass concentration of 0.4%, which is set aside;

[0066] (2) 100 g of honokiol was mixed with 90 g of hexadecyltrimethylammonium bromide, 15 g of N,N-dimethylformamide, and 8 g of polyethylene glycol to prepare a mixed solution for standby use;

[0067] (3) Sodium alginate was mixed with water to prepare a sodium alginate solution with a mass concentration of 1 g / ml, and then the sodium alginate solution and the mixed solution were mixed in a mass ratio of 1:2. After adjusting the pH to 7.5, N-hydroxysuccinimide was added, wherein the mass ratio of sodium alginate to N-hydroxysuccinimide was 1:0.05. After stirring for 10 minutes, a preheated solution and a zinc oxide suspension of equal mass to the sodium alginate solution were added respectively, and the reaction was heated at 70°C for 2 hours. The precipitate was collected by centrifugation and dried at 60°C overnight to obtain a ZnO-ZIF-8 composite material loaded with magnolol.

[0068] The present invention also conducts cell growth curve determination and in vitro antibacterial activity experiments on the composite materials prepared in Example 1 and Comparative Examples 1-3.

[0069] 1. Growth curve determination:

[0070] (1) Test bacteria: Ralstonia solanacearum (isolated from naturally diseased tobacco plants in Pengshui County, Chongqing, and now preserved in the laboratory of the Tobacco College of Guizhou University);

[0071] (2) Growth curve determination: The growth curve of Ralstonia solanacearum was measured by the optical density (OD 600 ) to measure.

[0072] First, a fresh overnight culture of Ralstonia solanacearum solution (OD 600 =1) Add to medium B (glucose: 10 g, yeast powder: 1 g, beef extract: 3 g, peptone: 5 g, add water to 1000 ml) and dilute to 10 4 Specifically, the bacterial suspension was inoculated into 30 mL of medium B in a culture bottle, and then the composite material sample and the honokiol sample of Example 1 were added to the cultured bacteria, respectively, so that the final sample concentrations in each culture bottle were 0, 25, 50, 100, and 200 μg / mL, respectively. The samples were cultured at 28° C., and samples (2 mL) were collected every 4 hours, and the cell concentration was detected at 600 nm using an ultraviolet spectrophotometer.

[0073] The results are as follows Figure 3 (Honokiol), Figure 4(Composite material) shown, analysis Figure 3 , Figure 4 The results show that:

[0074] From the growth curve of honokiol ( Figure 3 ) It can be seen that honokiol has a significant antibacterial effect on Ralstonia solanacearum, and its antibacterial effect is related to its concentration. With the increase of honokiol concentration, the inhibitory effect of honokiol on Ralstonia solanacearum gradually increases, among which 200μg / mL has the most significant effect. The growth curve of the composite material is determined ( Figure 4 ) The antibacterial effect is also dependent on concentration, and the antibacterial effect increases with the increase of concentration. However, compared with the use of magnolol alone, the antibacterial effect of the composite material is more significant. At the same concentration, the antibacterial effect of the composite material is stronger. When the concentration is 200μg / mL, OD 600 It is about 0.3, significantly lower than 0.7 of magnolol.

[0075] Based on the conclusion of the above experiment, the growth curves of Comparative Examples 1-3 were also determined. The experimental process was the same as the above method. The final sample concentrations in the culture flask were 50, 100, and 200 μg / mL, respectively. The results are as follows: Figure 5-7 As shown, the analysis results show that:

[0076] Compared with Example 1, the antibacterial effects of Comparative Examples 1-3 have all decreased, among which the effect of Comparative Example 1 has decreased most significantly, indicating that the composite material directly prepared by the solvent method has a poor loading effect and poor antibacterial ability, and cannot be well used for plant virus control. Comparative Example 2 directly uses sodium alginate gel, and does not use polyethylene glycol and N-hydroxysuccinimide to prepare the composite material, and its antibacterial effect also decreases significantly, indicating that its loading rate is also low. It can be shown that the composite material prepared by the preparation method disclosed in the present invention has a high loading rate and can achieve good antibacterial and antibacterial properties.

[0077] 2. In vitro antibacterial activity test

[0078] (1) Test strain: Ralstonia solanacearum;

[0079] (2) Composite material’s activity in inhibiting bacterial wilt:

[0080] The strain was cultured in medium B overnight and fresh bacterial suspension (OD 600 =1), which is equivalent to about 1×10 9 Colony forming unit (CFU) / mL, and then dilute the bacterial suspension to 1×10 5 CFU / mL.

[0081] According to the conclusion of Experiment 1, the composite material samples obtained in Example 1 and Comparative Example 3 were added to the bacterial suspension to obtain the following concentrations: 0, 25, 50, 100, and 200 mg / L. After the bacterial wilt cells were cultured at 30°C for 24 hours, the number of CFU on the casein peptone glucose (CPG) agar medium plate was counted to monitor the viable bacteria. The data obtained are as follows: Figure 8 (Example 1), Fig. 9 As shown in (Comparative Example 3), analysis Figure 8-Figure 9 The results show that:

[0082] From the results of the in vitro antibacterial plate, the results are consistent with the growth curve determination, and the antibacterial effect depends on the antibacterial concentration. As the concentration increases, the antibacterial effect gradually increases. However, when the concentration reaches 50 mg / L, the antibacterial effect of the composite material of Example 1 is significantly better than that of the composite material prepared in Comparative Example 3, especially when the concentration reaches 100 mg / L, the composite material prepared in Example 1 has a very significant effect in inhibiting bacterial wilt, and almost no colonies exist. This example also shows that the composite material prepared by the present invention can prevent and treat bacterial wilt at a concentration of ≥100 mg / L, and the effect is good.

[0083] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should be included in the scope of the claims of the present invention. The techniques, shapes, and structural parts not described in detail in the present invention are all known technologies.

Claims

1. A method for preparing a ZnO-ZIF-8 composite material loaded with honokiol, characterized in that: The method comprises the following steps: (1) Mix 2-methylimidazole and N,N-dimethylformamide, stir and dissolve, and then preheat to obtain a preheated solution for standby use; mix nano zinc oxide with water to prepare a zinc oxide suspension for standby use; (2) mixing honokiol with hexadecyltrimethylammonium bromide, N,N-dimethylformamide and polyethylene glycol to prepare a mixed solution for standby use; (3) Mixing sodium alginate and water to prepare a sodium alginate solution with a concentration of 0.5-1 g / ml, then mixing the sodium alginate solution with the mixed solution, adjusting the pH to 7.5-8, adding N-hydroxysuccinimide, stirring for 5-10 minutes, adding the preheated solution and zinc oxide suspension, heating the reaction for 2 hours, and collecting the precipitate by centrifugation; (4) mixing the obtained precipitate with water, adjusting the pH to 8-9, stirring for 5-10 minutes and then standing for 10-12 hours, collecting the precipitate by centrifugation, and drying to obtain a ZnO-ZIF-8 composite material loaded with honokiol; The mass ratio of the sodium alginate to N-hydroxysuccinimide is 1:(0.05-0.1).

2. A method for preparing a ZnO-ZIF-8 composite material loaded with honokiol according to claim 1, characterized in that, The mass ratio of the 2-methylimidazole to N,N-dimethylformamide is 1:

100.

3. A method for preparing a ZnO-ZIF-8 composite material loaded with honokiol according to claim 2, characterized in that, The mass concentration of zinc oxide in the zinc oxide suspension is 0.4%.

4. A method for preparing a ZnO-ZIF-8 composite material loaded with honokiol according to claim 3, characterized in that: The mass ratio of honokiol, hexadecyltrimethylammonium bromide, N,N-dimethylformamide and polyethylene glycol is 100:90:15:(8-12).

5. A method for preparing a ZnO-ZIF-8 composite material loaded with honokiol according to claim 4, characterized in that, The temperature of the preheated solution is 65-75°C.

6. A method for preparing a ZnO-ZIF-8 composite material loaded with honokiol according to claim 5, characterized in that, The heating reaction in step (3) is carried out at 70-75° C. for 2 h.

7. A method for preparing a ZnO-ZIF-8 composite material loaded with honokiol according to claim 6, characterized in that, The mass ratio of the sodium alginate solution: the mixed solution: the preheated solution: the zinc oxide suspension is 1:2:1:

1.

8. The application of the ZnO-ZIF-8 composite material loaded with honokiol prepared according to claim 1, characterized in that, The composite material is used for preventing and treating bacterial wilt caused by Ralstonia solanacearum.

9. The application of the ZnO-ZIF-8 composite material loaded with honokiol prepared according to claim 1, characterized in that, The composite material is used for preventing and controlling Ralstonia solanacearum.

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