A nano-encapsulated 8-hydroxyquinoline composition, and a method of making and using the same

Abstract

This invention belongs to the field of agricultural technology and relates to a nano-encapsulated 8-hydroxyquinoline composition, its preparation method, and its applications. The 8-hydroxyquinoline composition comprises core-shell structured nanoparticles; the core-shell structured nanoparticles consist of a core layer, an intermediate layer, and a shell layer from the inside out; the core layer is formed by the self-assembly of 8-hydroxyquinoline copper and a natural polymer material. The 8-hydroxyquinoline composition of this invention possesses a core-shell structure, exhibiting not only high activity but also significant sustained-release and targeted response characteristics, greatly improving the antibacterial efficiency against plant pathogens and showing broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of agricultural technology and relates to a nano-encapsulated 8-hydroxyquinoline composition, its preparation method, and its application. Background Technology

[0002] With the development of modern agriculture and the continuous expansion of crop planting areas, the demand for pesticides, as one of the key factors in ensuring crop growth, is also increasing. Due to the low utilization rate of pesticides, achieving significant effects currently relies mainly on increasing the dosage. However, the excessive use of pesticides not only pollutes the ecosystem and soil but also poses certain risks to food safety.

[0003] Controlled-release formulations (CRFs) continuously release active substances to specific targets at preset concentrations and times, making pesticide formulations more rational, efficient, safe, economical, and convenient to use. Constructing environmentally friendly pesticide delivery systems (PDS) based on multifunctional nanocarriers can effectively solve the drawback of low utilization rates of conventional pesticides, achieving water-based, nano-sized, targeted, efficient, and safe pesticide systems. Applying nanomaterials to pesticide slow-release agents can enhance pesticide adhesion and penetration, improve biological effects, control release rates, and reduce environmental impact. Quinoline copper, a commonly used pesticide fungicide, exerts its bactericidal effect by inhibiting pathogen DNA synthase through the slow release of copper ions. It has a broad bactericidal spectrum, multiple mechanisms, and high safety. However, when mixed with alkaline pesticides or foliar fertilizers containing metal ions, its efficacy may be reduced or phytotoxicity may occur. Currently, there are reports of loading pesticides onto nanocarriers to obtain nanopesticides with small particle size and strong adsorption. However, problems remain regarding the inability to simultaneously achieve controlled release and activity, high cost, and poor stability. Summary of the Invention

[0004] To address the aforementioned deficiencies, this invention provides a nano-encapsulated 8-hydroxyquinoline composition, its preparation method, and its applications. This 8-hydroxyquinoline composition has a core-shell structure, exhibiting not only strong activity but also significant sustained-release and targeted response characteristics, greatly improving antibacterial efficiency. In particular, it demonstrates significant inhibitory activity against rice sheath blight and citrus gummosis.

[0005] The purpose of this invention is to provide a nano-encapsulated 8-hydroxyquinoline composition, wherein the 8-hydroxyquinoline composition comprises core-shell structured nanoparticles; the core-shell structured nanoparticles consist of a core layer, an intermediate layer, and a shell layer from the inside out; The core layer is formed by the self-assembly of 8-hydroxyquinoline copper and natural polymer materials.

[0006] The 8-hydroxyquinoline composition of this invention is made into a core-shell structure, with the synergistic antibacterial active ingredient and copper ions forming the core, and then a dual response of intermediate and shell layers is deposited, ultimately achieving the purpose of improving sustained-release effect, increasing targeted release efficiency, and enhancing biological activity.

[0007] Preferably, in the above technical solution, the chemical structural formula of the 8-hydroxyquinoline copper is as follows: .

[0008] Preferably, in the above technical solution, the natural polymer material is corn starch or sweet potato starch with a particle size of 3-5 μm. This technical solution utilizes the property that the hydroxyl groups on the starch molecular chain can interact with the active complex through hydrogen bonds and physically encapsulate the hydrophobic complex particles, acting as a steric stabilizer to prevent the nanocore from agglomerating in subsequent steps and providing a template for the bonding of subsequent materials.

[0009] Preferably, in the above technical solution, the intermediate layer is a mesoporous silica transition layer with a pore size of 3-5 nm and a particle size of 50-60 nm. This invention deposits mesoporous silica in the intermediate layer to reinforce the structure, forming a first adjustable barrier to control the initial release efficiency, while simultaneously providing reaction sites for subsequent shell modification.

[0010] Preferably, in the above technical solution, the shell layer is a stimulus-responsive polymer shell layer, composed of an amphiphilic polymer and a hydrophobically modified cellulose derivative; the amphiphilic polymer is Pluronic F127; and the hydrophobically modified cellulose derivative is hydrophobically modified ethyl cellulose. Specifically, Pluronic F127 is a commercially available product from Meiluo Technology; the hydrophobically modified ethyl cellulose can be produced using conventional methods. The amphiphilic polymer and hydrophobically modified cellulose derivative of this invention, as a responsive shell layer, can release substances based on pH changes in the disease microenvironment and enzyme-sensitive substrates, achieving precise release with dual responses, avoiding non-targeted release, and reducing the dosage.

[0011] This invention also provides a method for preparing a nano-encapsulated 8-hydroxyquinoline composition, the method comprising the following steps: Step 1: Core Layer Construction: First, dissolve 8-hydroxyquinoline in an aqueous ethanol solution and heat to 50-60℃. Add anhydrous copper sulfate and react for 5-6 hours. Then, add pregelatinized starch to the above reaction system and react for 2-3 hours under weakly acidic conditions and stirring. Add an appropriate amount of crosslinking agent and continue the reaction for 20-30 minutes. Cool to obtain a suspension. First, coordinate and assemble 8-hydroxyquinoline with copper ions to form active ingredients and synergistic antibacterial mechanisms. Then, interact with the hydroxyl groups on the starch molecular chain through hydrogen bonds to form a coating, which plays a steric stabilizing role and can prevent the subsequent aggregation of active ingredients. Finally, use a trace amount of crosslinking agent to form a crosslinking network between starch molecules to enhance the mechanical strength of the core and prevent it from disintegrating during subsequent stirring.

[0012] Step 2, Intermediate Layer Deposition: The suspension obtained in Step 1 is placed in an ice-water bath, an appropriate amount of chitosan is added, and the mixture is stirred evenly. Tetraethyl silicate ethanol solution is slowly added dropwise using a constant pressure dropping funnel. After the addition is complete, the mixture is placed at room temperature, and an appropriate amount of ammonia is added and the reaction is continuously stirred for 3-4 hours. The mixture is then centrifuged, the precipitate is collected, and the precipitate is washed with ethanol solution to obtain nanoparticles with a deposited mesoporous silica transition layer. These nanoparticles are dispersed in phosphate buffer solution and sonicated for 5-10 minutes to obtain a nanoparticle dispersion system. First, amino-rich chitosan is adsorbed on the core layer surface and carries a positive charge, which can effectively adsorb negatively charged silica oligomers and deposit them directionally on their surface. Then, under the catalysis of ammonia, disordered mesoporous channels are formed in the silica network using starch and chitosan as templates. The formed mesoporous silica can not only increase the mechanical strength and stability of the nanoparticles, but also form the first regulatory barrier for drug release, controlling the initial release rate. At the same time, the silanol groups on the silica surface can provide reaction sites for the subsequent shell layer.

[0013] Step 3: Shell coating: The amphiphilic polymer and hydrophobically modified cellulose derivative are dispersed in acetone, and an appropriate amount of p-carboxybenzaldehyde is added. The mixture is reacted at 50-60℃ for 3-4 hours with stirring. The mixture is then added dropwise to the nanoparticle dispersion system from Step 2, and the temperature is raised to 65-70℃ for 20-30 minutes. After the reaction is completed, the mixture is cooled to room temperature, and an appropriate amount of adipic acid dihydrazide is added and reacted for 2-3 hours. The mixture is then centrifuged, washed, and freeze-dried to obtain the 8-hydroxyquinoline composition. The amphiphilic polymer Pluronic F127 of this invention is a PEO-PPO-PEO triblock copolymer. When the temperature is higher than its critical micelle temperature, the hydrophobic PPO segments aggregate with each other, driving the entire molecule to oriented on the hydrophobic surface of the nanoparticles, forming a dense polymer shell. The hydrazone bond formed by the introduced aldehyde group and the subsequent hydrazide group can be rapidly hydrolyzed and broken under the weakly acidic conditions after plant pathogen infection, resulting in shell dissociation and pH-triggered release. At the same time, the polysaccharide bonds of the introduced ethyl cellulose and the unsubstituted starch or chitosan are specifically degraded by enzymes such as cellulase and chitinase secreted by plant pathogens, achieving enzyme-triggered release. Ultimately, the slow and precise release of the 8-hydroxyquinoline composition is achieved, which can reduce leakage at non-target sites, reduce the risk of phytotoxicity and cost.

[0014] Preferably, in step one of the above technical solution, the molar ratio of 8-hydroxyquinoline to anhydrous copper sulfate is 1:1; the mass ratio of starch to 8-hydroxyquinoline is 4-5:1; the 8-hydroxyquinoline is pre-dissolved in 10 times its weight of a 50% ethanol solution before addition; the starch is pre-dissolved in 20-25 times its volume of 60°C hot water for pregelatinization; the weak acid condition is pH=6.5±0.2; the crosslinking agent is a 0.5% glutaraldehyde aqueous solution, and the amount used is 25% of the starch mass.

[0015] Preferably, in step two of the above technical solution, the amount of chitosan used is 0.4-0.5 times the mass of 8-hydroxyquinoline; the chitosan is first dissolved in a 1% acetic acid solution before being added to the system; the tetraethyl silicate ethanol solution is a mixed solution of tetraethyl silicate and ethanol in a volume ratio of 1:2, and the dropping rate is 0.5 mL / min; the volume-to-mass ratio of tetraethyl silicate to 8-hydroxyquinoline is 2-4 mL:1 g; and the amount of ammonia added is 1 / 4 of the volume of tetraethyl silicate.

[0016] Preferably, in step three of the above technical solution, the mass ratio of the amphiphilic polymer to the hydrophobic modified cellulose derivative is 1:0.2-0.3; the amount of p-carboxybenzaldehyde is 1 / 10 of the total weight of the amphiphilic polymer and the hydrophobic modified cellulose derivative; the amount of adipic dihydrazide added is equivalent to the amount of p-carboxybenzaldehyde; the freeze-drying temperature is -40-50℃, and the time is 24-48h.

[0017] The present invention also provides the application of the above-mentioned 8-hydroxyquinoline composition in the prevention and control of bacterial or fungal diseases of plants.

[0018] Advantages compared to existing technologies: This invention designs an 8-hydroxyquinoline composition into a core-shell structure. First, 8-hydroxyquinoline is coordinated and assembled with copper ions to form an active ingredient and a synergistic antibacterial mechanism. Mixing with starch improves its stability. Then, a mesoporous silica transition layer is deposited on the surface of the core layer to form the first regulatory barrier for drug release, controlling the initial release rate. At the same time, the silanol groups on the silica surface can also provide reaction sites for subsequent shell layers. Finally, pH-sensitive units and enzyme-sensitive units are introduced on the surface of the intermediate layer to form a shell structure with dual pH / enzyme response characteristics, achieving precise targeted release.

[0019] This invention employs precise nano- and core-shell structure control technology, ensuring reliable processing. The raw materials used, such as starch, chitosan, and silica, are low-cost, biodegradable, safe, and environmentally friendly natural composite materials. This nano-8-hydroxyquinoline composition combines the intrinsic bactericidal activity of 8-hydroxyquinoline with the antibacterial properties of copper ions, significantly enhancing efficacy and providing good sustained-release properties. It enables targeted and precise release, improving bactericidal efficiency while reducing dosage and further lowering costs. Attached Figure Description

[0020] Figure 1 This is the 1H NMR spectrum of 8-hydroxyquinoline copper of the present invention; Figure 2 The inhibition rate of 8-hydroxyquinoline copper and nano-8-hydroxyquinoline copper obtained in Example 3 against Fusarium verticillata at a concentration of 3.125 mg / L is shown in the figure. Detailed Implementation

[0021] The above-described technical features of the present invention and the technical features specifically described below (such as in the embodiments) can be combined with each other to form new or preferred technical solutions. However, the present invention is not limited to these embodiments, nor are these embodiments limited in any way.

[0022] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the formulations involved in the following examples are all commercially available products that can be purchased from the market.

[0023] The present invention will be further described in detail below with reference to embodiments: Example 1: Core layer construction 36.3 g (250 mmol) of 8-hydroxyquinoline was dissolved in 10 times its volume of 67% ethanol aqueous solution, heated to 55 °C, and 40.0 g (250 mmol) of anhydrous copper sulfate was added. The reaction was allowed to proceed for 6 h. During the reaction, the solution color changed from dark green to black. Then, pregelatinized starch (150 g dissolved in 3500 mL of 60 °C hot water) was added to the above reaction system, and the reaction was allowed to proceed for 2 h under stirring at pH 6.5. 35 mL of 0.5% glutaraldehyde aqueous solution was added, and the cross-linking reaction was allowed to proceed for 30 min. The mixture was then cooled to room temperature to obtain a suspension. The main reaction process is shown below: (1) 8-Hydroxyquinoline (8-HQ) and copper ions (Cu) 2+ The coordination reaction of ) is shown in the following equation:

[0024] The proton NMR spectrum of 8-hydroxyquinoline copper (CuHq) is shown below. Figure 1 As shown, the molecular structure is as follows:

[0025] 1H NMR (500 MHz, DMSO) δ 8.96 (dd, J = 4.8, 1.6 Hz, 1H), 8.73 – 8.68(m, 1H), 7.80 (dd, J = 8.4, 4.8 Hz, 1H), 7.57 (d, J = 8.1 Hz, 1H), 7.54 –7.50 (m, 1H), 7.32 – 7.26 (m, 1H). (2) Starch molecules cross-link through glutaraldehyde, and the reaction formula is as follows:

[0026] Example 2: Intermediate layer deposition The suspension obtained in Example 1 was placed in an ice-water bath (4°C), and 15g of chitosan (dissolved in 1% acetic acid solution) was added. The mixture was stirred at 300 rpm, and a tetraethyl orthosilicate ethanol solution (75 mL tetraethyl orthosilicate and 150 mL ethanol) was slowly added dropwise at a rate of 0.5 mL / min using a constant-pressure dropping funnel. After the addition was complete, the mixture was allowed to stand at room temperature, and 18.75 mL of 25% ammonia solution was added. The mixture was stirred continuously for 4 hours, centrifuged at 12000 rpm for 10 minutes, and the precipitate was collected. The precipitate was washed twice with ethanol solution to obtain nanoparticles with a deposited mesoporous silica transition layer. These nanoparticles were then dispersed in phosphate buffer and sonicated for 5 minutes to obtain a nanoparticle dispersion system. The main reaction process is shown below: The hydrolysis and condensation of tetraethyl silicate are shown in the following reaction formula:

[0027] The hydrolysis reaction is as follows: ; The condensation reaction is: .

[0028] Example 3: Shell Coating 72g of Pluronic F127 and 20g of hydrophobically modified cellulose derivative were dispersed in 1400mL of acetone. 9.2g of p-carboxybenzaldehyde (with a catalytic amount of p-toluenesulfonic acid) was added, and the mixture was reacted at 60℃ for 3h. The mixture was then added dropwise to the nanoparticle dispersion system of Example 2 while stirring, and the temperature was raised to 65℃ for 30min. After the reaction, the mixture was cooled to room temperature, and 9.2g of adipic acid dihydrazide was added and reacted for 2h. The mixture was centrifuged at 15000rpm for 20min, washed, and freeze-dried at -50℃ for 48h to obtain the nano-8-hydroxyquinoline composition. The main reaction process is shown below: (1) The esterification / condensation reaction of Prönnicke F127 / ethyl cellulose with p-carboxybenzaldehyde is shown in the following reaction formula:

[0029] (2) The aldehyde group and the acylhydrazine group form a pH-sensitive hydrazone bond, and the reaction formula is as follows:

[0030] In the presence of plant pathogens, these pathogens release acidic liquids, creating a weakly acidic environment at the site of infection. Simultaneously, they secrete cellulase and chitinase. Therefore, the nano-8-hydroxyquinoline composition obtained in this invention, upon encountering plant pathogens, undergoes a targeted release response, thereby achieving antibacterial effects. The main mechanism of this targeted release is as follows: (1) Hydrolysis of the shell hydrazone bond

[0031] (2) Dissociation of the core CuHq complex

[0032] Example 4: Activity Verification To demonstrate the inhibitory effect of the nano-8-hydroxyquinoline copper composition of the present invention on the target fungus, the inventors conducted a bioactivity assay.

[0033] A method for testing the antibacterial activity of nano-encapsulated 8-hydroxyquinoline copper composition was developed. 0.0200 ± 0.0002 g of the target compound was weighed, dissolved in 0.4 mL of dimethyl sulfoxide, and 10 mL of a 100 mg / L stock solution was prepared. Potato dextrose agar medium was prepared and autoclaved at 121℃. Under aseptic conditions, the drug solution was added to the melted medium to prepare a drug-containing medium. The drug-containing medium was poured into Petri dishes, and pathogenic bacterial pellets with a diameter of 5 mm were inoculated. The dishes were then incubated at 25℃ under darkness. Blank and solvent controls were set up to eliminate the influence of the solvent. When the negative control colony diameter reached 60–70 mm, the colony diameter was measured, the inhibition zone diameter was calculated, and the average value was taken as the actual colony diameter.

[0034] The inhibition rate against the target fungus is calculated using the following formula:

[0035] The antibacterial activity test results of the nano-encapsulated 8-hydroxyquinoline copper composition are shown in Tables 1-2 and 2-3. Figure 2 As shown: 1. The results of the indoor antifungal activity test of 8-hydroxyquinoline compounds at a concentration of 50 mg / L are shown in Table 1.

[0036] Table 1. Results of antifungal activity test (%)

[0037] As shown in Table 1, under the condition of a concentration of 50 mg / L, the nano-8-hydroxyquinoline copper of Example 3 of this invention exhibited varying degrees of inhibitory effects on the 10 plant pathogens studied. Specifically, both 8-hydroxyquinoline and nano-8-hydroxyquinoline copper showed significant inhibitory effects on the 10 plant pathogens, with inhibition rates exceeding 50%. This indicates that the nano-8-hydroxyquinoline copper prepared in this invention, like 8-hydroxyquinoline, exhibits superior antibacterial activity in inhibiting specific plant pathogens such as pine shoot blight, rice sheath blight, rice blast, and *Potentilla chinensis*. In particular, the inhibition rate against rice sheath blight and citrus anthracnose is above 94%, demonstrating a significant antibacterial effect.

[0038] 2. The results of the indoor antifungal LC50 activity test of 8-hydroxyquinoline compounds are shown in Table 2.

[0039] Table 2. Results of antifungal LC50 activity test (mg / L)

[0040] As shown in Table 2, both 8-hydroxyquinoline and the nano-8-hydroxyquinoline copper of this invention exhibit strong activity in inhibiting rice sheath blight pathogens, and significantly inhibit the growth and reproduction of the pathogen even at low concentrations. Simultaneously, the inhibitory effects of both 8-hydroxyquinoline copper and nano-8-hydroxyquinoline copper on citrus anthracnose are particularly significant. Furthermore, the results of treatment with nano-8-hydroxyquinoline copper and 8-hydroxyquinoline show that the activity concentration of nano-8-hydroxyquinoline copper against various pathogens is reduced to varying degrees. These results indicate that the nano-8-hydroxyquinoline copper of this invention, after treatment with nano- and core-shell technologies, has improved its antibacterial efficiency and achieves significant antibacterial effects at low concentrations, especially in combating rice sheath blight and citrus anthracnose. This nanocomposite material is a highly promising fungicide.

[0041] 3. The inhibition rates of 8-hydroxyquinoline copper and the nano-8-hydroxyquinoline copper obtained in Example 3 against Fusarium verticillata were tested at a concentration of 3.125 mg / L. The results are as follows: Figure 2 As shown.

[0042] from Figure 2 As can be seen, taking *Fusarium verticillatum* as an example, under the condition of 3.125 mg / L, the antibacterial rate of the nano-8-hydroxyquinoline copper obtained in this invention is significantly higher than that of 8-hydroxyquinoline copper. Through experimental data analysis, it can be observed that the core-shell treated 8-hydroxyquinoline copper exhibits a more superior antibacterial effect, indicating that the application of nanotechnology and targeted regulation can effectively improve the performance of traditional pesticides. Furthermore, the nano-8-hydroxyquinoline copper of this invention still maintained an antibacterial efficiency of over 30% on the 9th day of the experiment, while the antibacterial efficiency of 8-hydroxyquinoline copper decreased significantly. This indicates that the nano-8-hydroxyquinoline copper not only has high antibacterial activity in the short term, but also extends its pesticide release cycle, which has important practical significance for agricultural production.

[0043] In summary, this invention not only successfully achieved efficient nano-encapsulation of CuHq and precise control of its core-shell structure, but also effectively extended the release cycle and directed release of pesticides through the application of nanotechnology and core-shell technology. This improved the efficiency of pesticide use, reduced the amount of pesticides used, reduced pollution, and also protected crops.

[0044] Finally, it should be emphasized that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A nano-encapsulated 8-hydroxyquinoline composition, characterized in that, The 8-hydroxyquinoline composition comprises core-shell structured nanoparticles; the core-shell structured nanoparticles consist of a core layer, an intermediate layer, and a shell layer from the inside out. The core layer is formed by the self-assembly of 8-hydroxyquinoline copper and natural polymer materials.

2. The nano-encapsulated 8-hydroxyquinoline composition according to claim 1, characterized in that, The chemical structural formula of the 8-hydroxyquinoline copper is shown below: 。 3. The nano-encapsulated 8-hydroxyquinoline composition according to claim 1, characterized in that, The natural polymer material is corn starch or sweet potato starch with a particle size of 3-5 μm.

4. The nano-encapsulated 8-hydroxyquinoline composition according to claim 1, characterized in that, The intermediate layer is a mesoporous silica transition layer with a pore size of 3-5 nm and a particle size of 50-60 nm.

5. The nano-encapsulated 8-hydroxyquinoline composition according to claim 1, characterized in that, The shell is a stimulus-responsive polymer shell, composed of an amphiphilic polymer and a hydrophobically modified cellulose derivative; the amphiphilic polymer is Pluronic F127; and the hydrophobically modified cellulose derivative is hydrophobically modified ethyl cellulose.

6. A method for preparing a nano-encapsulated 8-hydroxyquinoline composition according to any one of claims 1-5, characterized in that, The preparation method includes the following steps: Step 1, Core layer construction: First, dissolve 8-hydroxyquinoline in an aqueous ethanol solution, heat to 50-60℃, add anhydrous copper sulfate, and react for 5-6 hours. Then, add pregelatinized starch to the above reaction system and react for 2-3 hours under weakly acidic conditions and stirring. Add an appropriate amount of crosslinking agent and continue the reaction for 20-30 minutes. Cool to obtain a suspension. Step 2, Intermediate Layer Deposition: Place the suspension obtained in Step 1 in an ice-water bath, add an appropriate amount of chitosan, stir evenly, and slowly add tetraethyl silicate ethanol solution dropwise using a constant pressure dropping funnel. After the addition is complete, place at room temperature, add an appropriate amount of ammonia water, and continue stirring for 3-4 hours. Centrifuge, collect the precipitate, wash with ethanol solution to obtain nanoparticles with deposited mesoporous silica transition layer, disperse in phosphate buffer, and sonicate for 5-10 minutes to obtain nanoparticle dispersion system. Step 3: Shell coating: The amphiphilic polymer and hydrophobically modified cellulose derivative are dispersed in acetone, and an appropriate amount of p-carboxybenzaldehyde is added. The mixture is reacted at 50-60℃ for 3-4 hours with stirring. The mixture is then added dropwise to the nanoparticle dispersion system from Step 2, and the temperature is raised to 65-70℃ for 20-30 minutes. After the reaction is completed, the mixture is cooled to room temperature, and an appropriate amount of adipic acid dihydrazide is added and reacted for 2-3 hours. The mixture is then centrifuged, washed, and freeze-dried to obtain the 8-hydroxyquinoline composition.

7. The method for preparing a nano-encapsulated 8-hydroxyquinoline composition according to claim 6, characterized in that, In step one, the molar ratio of 8-hydroxyquinoline to anhydrous copper sulfate is 1:1; the mass ratio of starch to 8-hydroxyquinoline is 4-5:1; before adding 8-hydroxyquinoline, it is pre-dissolved in 10 times its weight of a 50% ethanol solution; the starch is pre-dissolved in 20-25 times its volume of 60°C hot water for pregelatinization; the weak acid condition is pH=6.5±0.2; the crosslinking agent is a 0.5% glutaraldehyde aqueous solution, and the amount used is 25% of the starch mass.

8. The method for preparing a nano-encapsulated 8-hydroxyquinoline composition according to claim 6, characterized in that, In step two, the amount of chitosan used is 0.4-0.5 times the mass of 8-hydroxyquinoline; the chitosan is dissolved in a 1% acetic acid solution before being added to the system; the tetraethyl silicate ethanol solution is a mixture of tetraethyl silicate and ethanol in a volume ratio of 1:2, and the dropping rate is 0.5 mL / min; the volume-to-mass ratio of tetraethyl silicate to 8-hydroxyquinoline is 2-4 mL:1 g; and the amount of ammonia added is 1 / 4 of the volume of tetraethyl silicate.

9. The method for preparing a nano-encapsulated 8-hydroxyquinoline composition according to claim 6, characterized in that, In step three, the mass ratio of the amphiphilic polymer to the hydrophobic modified cellulose derivative is 1:0.2-0.3; the amount of p-carboxybenzaldehyde used is 1 / 10 of the total weight of the amphiphilic polymer and the hydrophobic modified cellulose derivative; the amount of adipic dihydrazide added is equivalent to the amount of p-carboxybenzaldehyde used; the freeze-drying temperature is -40-50℃, and the time is 24-48h.

10. The use of an 8-hydroxyquinoline composition as described in any one of claims 1-9 in the prevention and control of bacterial or fungal diseases of plants.

Images