Biodegradable antifungal composition as well as preparation method and application thereof

Abstract

The invention discloses a biodegradable antifungal composition as well as a preparation method and application thereof, and belongs to the technical field of antifungal products. The antifungal composition is prepared by loading cinnamyl aldehyde on cellulose and then packaging through a chitosan coating, the preparation method comprises the following steps: preparing a cellulose suspension, adding the cellulose suspension into an ethanol solution of cinnamyl aldehyde, uniformly stirring, filtering, precipitating and washing to obtain cinnamyl aldehyde cured cellulose; and adding the cinnamyl aldehyde cured cellulose into a chitosan solution, uniformly stirring, and after the cinnamyl aldehyde cured cellulose becomes yellow, filtering, precipitating and washing, and air-drying to a fixed weight, thereby obtaining the antifungal composition. The antifungal composition can be used for preparing antifungal products such as a fumigant, a coating, a soil conditioner and the like. The cinnamyl aldehyde in the antifungal composition disclosed by the invention can be kept stable and slowly released, so that the antifungal activity on plant pathogenic fungi is enhanced; the raw materials used for preparation are simple and natural, have the characteristic of degradability, and are environment-friendly.

Description

Technical Field

[0001] The present invention belongs to the technical field of antifungal products, and particularly relates to a biodegradable antifungal composition, a preparation method thereof, and an application thereof. Background Art

[0002] The widespread use of chemical fungicides has caused major environmental problems, including the persistence of chemical residues in food and soil and the enhancement of drug resistance of plant pathogens. At present, the prevention and control of agricultural diseases highly rely on chemical fungicides, which not only pollute the ecosystem but also pose risks to human health. Cinnamaldehyde, as a natural antifungal agent, is recognized for its strong biological activity, but its volatility and instability limit its practical application in the agricultural environment. Therefore, there is an urgent need for a sustainable, biodegradable and highly efficient antifungal composition that can slowly release while maintaining antifungal activity to enhance its long-term effectiveness in controlling fungi. Summary of the Invention

[0003] The present invention provides a biodegradable antifungal composition, a preparation method thereof, and an application thereof to solve the technical problems of chemical residues, enhanced drug resistance of plant pathogens, and ecological pollution existing in the use of existing fungicides. By using cellulose extracted from waste mushroom residues to stabilize cinnamaldehyde and encapsulating it in a chitosan-based polymer matrix, its antibacterial effectiveness and long-term effectiveness are improved; the antifungal combination can be used as a packaging material, fumigant, modifier, etc. for the storage and planting of plant seeds.

[0004] To solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A biodegradable antifungal composition is prepared by loading cinnamaldehyde with cellulose and then encapsulating it with a chitosan coating to obtain the antifungal composition (CeCACs).

[0006] Further, the loading content of cinnamaldehyde is 40%-85%.

[0007] Further, the concentration of the antifungal composition used is 40-115 μg / mL.

[0008] Further, the cellulose is prepared by the following method:

[0009] S1. Softening treatment: The mushroom residues are made into powder, suspended in water and soaked, filtered, and the obtained residue is soaked in sodium hydroxide solution and then filtered to obtain the softened product;

[0010] S2. Acid hydrolysis: The softened product is washed to neutral, resuspended in acetic acid, and heated at 70-100 °C, and then filtered to obtain the hydrolyzate;

[0011] S3. Alkali treatment: The hydrolyzate is added to a mixed solution containing hydrogen peroxide and sodium hydroxide, heated at 75 - 100 °C, filtered to obtain an alkali-treated product;

[0012] S4. Bleaching treatment: The alkali-treated product is washed, dispersed in a sodium hypochlorite solution for bleaching at 60 - 85 °C, filtered, and then further bleached with a hydrogen peroxide solution at 65 - 80 °C, filtered to obtain a bleached product;

[0013] S5. Ultrasonic treatment: The bleached product is added to a mixed solution containing nitric acid and hydrogen peroxide, subjected to ultrasonic treatment, the dense and obviously dispersed fibers are separated from the solution, washed to neutrality, and filtered to obtain the product.

[0014] The present invention also provides a preparation method of a biodegradable antifungal composition, comprising the following steps:

[0015] S6. Prepare a cellulose suspension, then add it to an ethanol solution of cinnamaldehyde, stir evenly, filter, wash the precipitate to obtain cinnamaldehyde-cured cellulose (CACs);

[0016] S7. The cinnamaldehyde-cured cellulose is added to a chitosan solution, stirred evenly, wait until the cinnamaldehyde-cured cellulose turns yellow, filter, wash the precipitate, and air-dry to a constant weight to obtain the antifungal composition (CeCACs).

[0017] Furthermore, in step S6, the concentration of the cellulose suspension is 5 - 15%; the mass ratio of cellulose to the volume of cinnamaldehyde is 0.67 - 2 g / mL.

[0018] Furthermore, in step S7, the concentration of the chitosan solution is 0.5 - 2%, and the mass ratio of cinnamaldehyde-cured cellulose to the volume of chitosan is 0.06 - 0.2 g / mL.

[0019] The present invention also provides an application of a biodegradable antifungal composition. Using this antifungal composition as a fumigant for fumigating before storing plant fruits;

[0020] The concentration of CeCACs in the fumigation area is 40 - 100 μg / mL.

[0021] The present invention also provides an application of a biodegradable antifungal composition. Using this antifungal composition as a packaging material for preparing seed coatings;

[0022] Carboxymethyl cellulose is also added to this packaging material, with a concentration of 0.3 - 0.8%;

[0023] The concentration of CeCACs is 85 - 110 μg / mL;

[0024] The dosage of the packaging material is 5 - 20 g / kg.

[0025] The present invention also provides an application of a biodegradable antifungal composition. Using this antifungal composition as a soil conditioner, the dosage is 15 - 40 g / m 2 .

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The antifungal composition of the present invention first loads cinnamaldehyde on cellulose and then encapsulates it with chitosan as a coating. During use, cinnamaldehyde can remain stable and be slowly released, having a long service life and enhancing the antifungal activity against phytopathogenic fungi.

[0028] The cellulose of the present invention is prepared from waste mushroom residues. The prepared cellulose has good heat resistance and can improve the waste utilization rate; both the used cinnamaldehyde and chitosan can be decomposed, having the characteristics of environmental protection.

[0029] In addition, the antifungal composition can be made into a fumigant for the storage of seeds and fruits, having better and broader antifungal properties; in addition, it can also be used as different types of products such as seed coating and soil conditioner to meet the usage requirements of different occasions. Specific Embodiments

[0030] To better understand the present invention, it is described in conjunction with the following examples. These examples belong to the protection scope of the present invention, but do not limit the protection scope of the present invention.

[0031] A biodegradable antifungal composition is prepared by loading cinnamaldehyde on cellulose and then encapsulating it with chitosan coating to obtain the antifungal composition (CeCACs).

[0032] The loading content of cinnamaldehyde is 40% - 85%.

[0033] The concentration of the antifungal composition used is 40 - 115 μg / mL.

[0034] Cellulose is prepared by the following method:

[0035] S1. Softening treatment: The mushroom residues are made into powder, suspended in water for soaking, filtered, and the obtained residue is soaked in sodium hydroxide solution and then filtered to obtain the softened product;

[0036] S2. Acid hydrolysis: The softened product is washed to neutrality, resuspended in acetic acid, and heated at 70 - 100 °C, filtered to obtain the hydrolyzate;

[0037] S3. Alkali treatment: The hydrolyzate is added to a mixed solution containing hydrogen peroxide and sodium hydroxide, heated at 75 - 100 °C, filtered to obtain the alkali-treated product;

[0038] S4. Bleaching treatment: The alkali-treated product is washed, dispersed in a sodium hypochlorite solution at 60 - 85 °C for bleaching, filtered, and then further bleached with a hydrogen peroxide solution at 65 - 80 °C, followed by filtration to obtain the bleached product;

[0039] S5. Ultrasonic treatment: The bleached product is added to a mixed solution containing nitric acid and hydrogen peroxide, and ultrasonic treatment is carried out to separate the dense and significantly dispersed fibers from the solution, followed by washing until neutral and then filtration to obtain the product.

[0040] A method for preparing a biodegradable antifungal composition, comprising the following steps:

[0041] S6. Prepare a cellulose suspension, then add it to an ethanol solution of cinnamaldehyde, stir evenly, filter, wash the precipitate to obtain cinnamaldehyde-cured cellulose (CACs);

[0042] S7. Add the cinnamaldehyde-cured cellulose to a chitosan solution, stir evenly, wait until the cinnamaldehyde-cured cellulose turns yellow, filter, wash the precipitate, and air-dry to a constant weight to obtain the antifungal composition (CeCACs).

[0043] In step S6, the concentration of the cellulose suspension is 5 - 15%, and the mass ratio of cellulose to the volume of cinnamaldehyde is 0.67 - 2 g / mL.

[0044] In step S7, the concentration of the chitosan solution is 0.5 - 2%, and the mass ratio of cinnamaldehyde-cured cellulose to the volume of chitosan is 0.06 - 0.2 g / mL.

[0045] An application of a biodegradable antifungal composition, using the antifungal composition as a fumigant for fumigating before storing plant fruits;

[0046] The concentration of CeCACs in the fumigation area is 40 - 100 μg / mL.

[0047] An application of a biodegradable antifungal composition, using the antifungal composition as a packaging material for preparing seed coatings;

[0048] The packaging material also adds carboxymethyl cellulose with a concentration of 0.3 - 0.8%;

[0049] The concentration of CeCACs is 85 - 110 μg / mL;

[0050] The dosage of the packaging material is 5 - 20 g / kg.

[0051] An application of a biodegradable antifungal composition, using the antifungal composition as a soil conditioner with a dosage of 15 - 40 g / m 2 .

[0052] Example 1

[0053] A biodegradable antifungal composition, in which cinnamaldehyde is loaded on cellulose and then encapsulated with a chitosan coating to obtain the antifungal composition (CeCACs).

[0054] The loading content of cinnamaldehyde is 40%-85%.

[0055] The concentration of the antifungal composition used is 40-115 μg / mL.

[0056] Cellulose is prepared by the following method:

[0057] S1. Softening treatment: Mushroom residue is made into powder, suspended in water and soaked, filtered, and the obtained residue is soaked in sodium hydroxide solution and then filtered to obtain the softened product;

[0058] S2. Acid hydrolysis: The softened product is washed to neutrality, resuspended in acetic acid, and heated at 70 °C, filtered to obtain the hydrolyzate;

[0059] S3. Alkali treatment: The hydrolyzate is added to a mixed solution containing hydrogen peroxide and sodium hydroxide, heated at 75 °C, filtered to obtain the alkali-treated product;

[0060] S4. Bleaching treatment: The alkali-treated product is washed, dispersed in sodium hypochlorite solution at 60 °C for bleaching, filtered and then further bleached with hydrogen peroxide solution at 65 °C, filtered to obtain the bleached product;

[0061] S5. Ultrasonic treatment: The bleached product is added to a mixed solution containing nitric acid and hydrogen peroxide, ultrasonically treated, the dense and obviously dispersed fibers are separated from the solution, and then washed to neutrality and filtered to obtain the product.

[0062] A preparation method of a biodegradable antifungal composition includes the following steps:

[0063] S6. Prepare a cellulose suspension, then add it to an ethanol solution of cinnamaldehyde, stir evenly, filter, wash the precipitate to obtain cinnamaldehyde-cured cellulose (CACs);

[0064] S7. The cinnamaldehyde-cured cellulose is added to a chitosan solution, stirred evenly, wait until the cinnamaldehyde-cured cellulose turns yellow, filter, wash the precipitate, and air-dry to a constant weight to obtain the antifungal composition (CeCACs).

[0065] In step S6, the concentration of the cellulose suspension is 5%; the mass ratio of cellulose to the volume of cinnamaldehyde is 2 g / L.

[0066] In step S7, the concentration of the chitosan solution is 0.5%, and the mass ratio of cinnamaldehyde-cured cellulose to the volume of chitosan is 0.06 g / mL.

[0067] Example 2

[0068] A biodegradable antifungal composition is prepared by loading cinnamaldehyde on cellulose and then encapsulating it with a chitosan coating to obtain the antifungal composition (CeCACs).

[0069] The loading content of cinnamaldehyde is 40%-85%.

[0070] The concentration of the antifungal composition used is 40-115 μg / mL.

[0071] Cellulose is prepared by the following method:

[0072] S1. Softening treatment: The mushroom residue is made into powder, suspended in water and soaked, filtered, and the obtained residue is soaked in sodium hydroxide solution and then filtered to obtain the softened product;

[0073] S2. Acid hydrolysis: The softened product is washed to neutral, resuspended in acetic acid, and heated at 80°C, filtered to obtain the hydrolyzate;

[0074] S3. Alkali treatment: The hydrolyzate is added to a mixed solution containing hydrogen peroxide and sodium hydroxide, heated at 85°C, filtered to obtain the alkali-treated product;

[0075] S4. Bleaching treatment: The alkali-treated product is washed, dispersed in sodium hypochlorite solution for bleaching at 65°C, filtered and then further bleached with hydrogen peroxide solution at 70°C, filtered to obtain the bleached product;

[0076] S5. Ultrasonic treatment: The bleached product is added to a mixed solution containing nitric acid and hydrogen peroxide, ultrasonically treated, the dense and obviously dispersed fibers are separated from the solution, washed to neutral, and filtered to obtain the product.

[0077] A preparation method of a biodegradable antifungal composition includes the following steps:

[0078] S6. Prepare a cellulose suspension, then add it to an ethanol solution of cinnamaldehyde, stir evenly, filter, wash the precipitate to obtain cinnamaldehyde-cured cellulose (CACs);

[0079] S7. Add the cinnamaldehyde-cured cellulose to a chitosan solution, stir evenly, wait until the cinnamaldehyde-cured cellulose turns yellow, filter, wash the precipitate, and air-dry to a constant weight to obtain the antifungal composition (CeCACs).

[0080] In step S6, the concentration of the cellulose suspension is 8%; the mass ratio of cellulose to the volume of cinnamaldehyde is 1.3 g / mL.

[0081] In step S7, the concentration of the chitosan solution is 0.8%, and the mass ratio of cinnamaldehyde-cured cellulose to the volume of chitosan is 0.08 g / mL.

[0082] Example 3

[0083] A biodegradable antifungal composition is prepared by loading cinnamaldehyde on cellulose and then encapsulating it with a chitosan coating to obtain the antifungal composition (CeCACs).

[0084] The loading content of cinnamaldehyde is 40%-85%.

[0085] The concentration of the antifungal composition used is 40-115 μg / mL.

[0086] Cellulose is prepared by the following method:

[0087] S1. Softening treatment: Mushroom residues are made into powder, suspended in water and soaked at 85°C for 2 h, filtered, and the obtained residue is soaked in 4% NaOH at a solid-liquid ratio of 1:10 at 80°C for 2 h, and then filtered to obtain the softened product;

[0088] S2. Acid hydrolysis: The softened product is washed with distilled water until the pH is 7 neutral, suspended in 50% acetic acid at a solid-liquid ratio of 1:50, and heated at 80°C for 2 h, filtered to obtain the hydrolyzate;

[0089] S3. Alkali treatment: The hydrolyzate is added to 300 mL of a mixed solution containing 5 wt.% H2O2 and 4 wt.% NaOH, heated at 85°C for 1 h, filtered to obtain the alkali-treated product;

[0090] S4. Bleaching treatment: The alkali-treated product is washed, then dispersed in a 4.5% NaOCl solution at 70°C for 1 h for bleaching, and further bleached with a 7.5% H2O2 solution at 70°C for 1 h to obtain a cream-colored bleached product;

[0091] S5. Ultrasonic treatment: The bleached product is added to a solution containing 1% HNO3 and 50 mL of 1.5% H2O2, ultrasonically treated for 2 h, the dense and obviously dispersed fibers are separated from the solution, and washed with NaOH solution and H2O until the pH is 7, filtered to obtain the product.

[0092] A preparation method of a biodegradable antifungal composition includes the following steps:

[0093] S6. Add the suspension of cellulose prepared in step S4 to an anhydrous ethanol solution, then add cinnamaldehyde, stir evenly, incubate overnight, filter, and wash the precipitate with anhydrous ethanol to remove the unloaded aldehyde substances to obtain cinnamaldehyde-cured cellulose (CACs);

[0094] S7. Add the cinnamaldehyde-cured cellulose to a chitosan solution, stir evenly, wait until the cinnamaldehyde-cured cellulose turns yellow, filter, wash the precipitate, and air-dry at 25°C to a constant weight to obtain the antifungal composition (CeCACs).

[0095] In step S6, the concentration of the cellulose suspension (mass / volume) is 10%; the volume ratio of the cellulose mass to cinnamaldehyde is 1 g / mL.

[0096] In step S7, the concentration of the chitosan solution is 1%, and the volume ratio of the cinnamaldehyde-cured cellulose mass to chitosan is 0.1 g / mL.

[0097] Example 4

[0098] A biodegradable antifungal composition, in which cinnamaldehyde is loaded on cellulose and then encapsulated with a chitosan coating to obtain the antifungal composition (CeCACs).

[0099] The loading content of cinnamaldehyde is 40%-85%.

[0100] The concentration at which the antifungal composition is used is 40-115 μg / mL.

[0101] Cellulose is prepared by the following method:

[0102] S1. Softening treatment: The mushroom residue is made into powder, suspended in water and soaked, filtered, and the obtained residue is soaked in sodium hydroxide solution and then filtered to obtain the softened product;

[0103] S2. Acid hydrolysis: The softened product is washed to neutrality, resuspended in acetic acid, and heated at 95°C, filtered to obtain the hydrolyzate;

[0104] S3. Alkali treatment: The hydrolyzate is added to a mixed solution containing hydrogen peroxide and sodium hydroxide, heated at 90°C, filtered to obtain the alkali-treated product;

[0105] S4. Bleaching treatment: The alkali-treated product is washed, dispersed in sodium hypochlorite solution at 80°C for bleaching, filtered, and then further bleached with hydrogen peroxide solution at 75°C, filtered to obtain the bleached product;

[0106] S5. Ultrasonic treatment: The bleached product is added to a mixed solution containing nitric acid and hydrogen peroxide, ultrasonically treated, the dense and obviously dispersed fibers are separated from the solution, and then washed to neutrality and filtered to obtain.

[0107] A method for preparing a biodegradable antifungal composition, comprising the following steps:

[0108] S6. Prepare a cellulose suspension, then add it to an ethanol solution of cinnamaldehyde, stir evenly, filter, wash the precipitate to obtain cinnamaldehyde-cured cellulose (CACs);

[0109] S7. Add the cinnamaldehyde-cured cellulose into the chitosan solution, stir evenly. Wait until the cinnamaldehyde-cured cellulose turns yellow, then filter, wash the precipitate, and air-dry it to a constant weight to obtain the antifungal composition (CeCACs).

[0110] In step S6, the concentration of the cellulose suspension is 13%; the mass ratio of cellulose to the volume of cinnamaldehyde is 0.8 g / mL.

[0111] In step S7, the concentration of the chitosan solution is 1.5%, and the mass ratio of cinnamaldehyde-cured cellulose to the volume of chitosan is 0.15 g / mL.

[0112] Example 5

[0113] A biodegradable antifungal composition is prepared by loading cinnamaldehyde on cellulose and then encapsulating it with a chitosan coating to obtain the antifungal composition (CeCACs).

[0114] The loading content of cinnamaldehyde is 40% - 85%.

[0115] The concentration at which the antifungal composition is used is 40 - 115 μg / mL.

[0116] Cellulose is prepared by the following method:

[0117] S1. Softening treatment: Make the mushroom residue into powder, suspend it in water and soak, filter, soak the obtained residue in sodium hydroxide solution, and then filter to obtain the softened product;

[0118] S2. Acid hydrolysis: Wash the softened product to neutral, re-suspend it in acetic acid, and heat it at 100 °C, then filter to obtain the hydrolyzate;

[0119] S3. Alkali treatment: Add the hydrolyzate into the mixed solution containing hydrogen peroxide and sodium hydroxide, heat it at 100 °C, then filter to obtain the alkali-treated product;

[0120] S4. Bleaching treatment: Wash the alkali-treated product, disperse it in sodium hypochlorite solution at 85 °C for bleaching, filter, and then further bleach it with hydrogen peroxide solution at 80 °C, and filter to obtain the bleached product;

[0121] S5. Ultrasonic treatment: Add the bleached product into the mixed solution containing nitric acid and hydrogen peroxide, perform ultrasonic treatment, separate the dense and obviously dispersed fibers from the solution, then wash to neutral and filter to obtain it.

[0122] A preparation method of a biodegradable antifungal composition includes the following steps:

[0123] S6. Prepare a cellulose suspension, then add it into the ethanol solution of cinnamaldehyde, stir evenly, filter, wash the precipitate to obtain cinnamaldehyde-cured cellulose (CACs);

[0124] In step S7, cinnamaldehyde-cured cellulose was added to the chitosan solution and stirred evenly. Wait until the cinnamaldehyde-cured cellulose turns yellow, then filter, wash the precipitate, and air-dry it to a constant weight to obtain the antifungal composition (CeCACs).

[0125] In step S6, the concentration of the cellulose suspension was 15%; the mass ratio of cellulose to the volume of cinnamaldehyde was 0.67 g / mL.

[0126] In step S7, the concentration of the chitosan solution was 2%, and the mass ratio of cinnamaldehyde-cured cellulose to the volume of chitosan was 0.2 g / mL.

[0127] Comparative Example 1

[0128] Same as Example 3, but the raw material of the antifungal composition lacked the chitosan coating, and step S7 was missing in the preparation method, to obtain CeCA.

[0129] Comparative Example 2

[0130] Same as Example 3, the cellulose preparation step was omitted, and the cellulose in the raw material and preparation method of the antifungal composition was replaced with gum arabic in equal amount, with a mass concentration of 1%, to obtain CeCAGa.

[0131] Experiment

[0132] I. Experiment Preparation

[0133] 1. Main raw materials and reagents: Mushroom residue, sourced from the Subtropical Crops Research Institute of Guangxi Zhuang Autonomous Region; Gum arabic, chitosan, and cinnamaldehyde were all commercially available products.

[0134] Fusarium oxysporum, Aspergillus flavus, Aspergillus niger, and Fusarium solani were all sourced from the strains stored in the Subtropical Crops Research Institute of Guangxi Zhuang Autonomous Region.

[0135] Tebuconazole suspension, with an active ingredient of 430 g / L, commercially available.

[0136] 2. Main equipment: Fourier transform infrared spectrometer (FTIR), IRTracer-100, Shimadzu, Japan; PerkinElmer thermal gravimetric analysis (TGA), PerkinElmer STA600, Waltham, USA; Contact angle measuring instrument, JY-82B Kruss DSA, Germany; Scanning electron microscope (SEM), Carl Zeiss, Germany; Colony counter, LC-JKQ-1, Shanghai Lichen; Microplate reader, Infinite 200pro, Thermo Fisher Scientific, USA; Ultraviolet spectrophotometer, SPECTRONIC 200, Thermo Fisher Scientific, USA.

[0137] 3. Using the preparation methods of Example 3, Comparative Example 1, and Comparative Example 2 of the present invention, CeCACs, CeCA, and CeCAGa were obtained respectively.

[0138] II. Sustained-release test

[0139] 1. Sample description

[0140] Weigh CeCACs, CeCA, CeCAGa, and CA respectively, and label them as #1, #2, #3, and #4. Take 7 samples for each group, with each sample weighing 2 g, to ensure that the cinnamaldehyde content in each group is the same.

[0141] 2. Test procedure

[0142] The pre-weighed weights of the products in each group were placed in an open container at room temperature (relative humidity 40%-50%). The content of cinnamaldehyde in the samples was tested starting from 0 d, and the result was recorded as C i ; Subsequently, it was tested every 5 d, and one sample from each group was used each time, and the result was recorded as C f ; During the test, the samples were first dispersed in absolute ethanol, ultrasonically treated for 30 min, and then the supernatant after treatment was taken; the remaining cinnamaldehyde content retained in the samples of each group was tested with a UV spectrophotometer (296 nm) for the supernatant.

[0143] Calculation formula:

[0144] Retention rate (%) = C f / C i × 100%

[0145] where, C i = initial cinnamaldehyde loading amount;

[0146] C f = amount of cinnamaldehyde retained after a specific time of air exposure.

[0147] 3. Result analysis

[0148] As can be seen from Table 1, the release of #1 is relatively slower than that of #2. The retention rate at 15 d is 78.8% for #1 and 50.0% for #2; at 30 d, the retention rate of #1 is 63.5%, while that of #2 is 41.00%; compared with #3, #1 has a higher retention rate. The retention rate of #3 at 30 d is only 32.2%; from the data, it can be seen that under the same conditions, CeCACs of the present invention have a higher retention rate.

[0149] Table 1 CA retention rate (%) of each group in the sustained-release test

[0150]

[0151]

[0152] It can be seen that the present application loads CA on Ce and then encapsulates it with a Cs coating, which plays a positive role in the sustained release of CA and significantly prolongs the sustained release period.

[0153] This is because cellulose has a lamellar structure. After the addition of cinnamaldehyde, the lamellar layers unfold, and the interaction between the two destroys the hydrogen bonds of cellulose, allowing CA to be better loaded on cellulose, and the two form a strong bond; and the chitosan coating used for encapsulation wraps up CeCA, which can achieve the slow release of CA during use, avoiding overall release and shortening the action time.

[0154] In addition, water contact angle measurements showed that cellulose fibers are highly hydrophilic, with a water contact angle of about 22°; after fixing chitosan acid (CA), the contact angle reached 63°, indicating that the absorption of CA did not make cellulose fibers hydrophobic, thus making CeCACs have a good dispersion effect in aqueous solution. After chitosan coating treatment, the water contact angle reached about 80°, ensuring that CeCACs can still be well dispersed in water and remain stable in an aqueous environment.

[0155] 3. Antifungal Test

[0156] 1. Sample Description

[0157] CeCACs, CeCA, CeCAGa, tebuconazole suspension, active ingredient 430 g / L, commercially available; marked as #1, #2, #3, 4#, 3 samples were taken from each group.

[0158] 2. Experimental process

[0159] Plant fungal pathogens: Fusarium oxysporum, Aspergillus flavus, Aspergillus niger and Fusarium solani. When culturing, Fusarium oxysporum and Fusarium solani use commercially available potato dextrose agar (PDA), and Aspergillus flavus and Aspergillus niger use commercially available Czapek medium.

[0160] Fusarium oxysporum and Fusarium solani were cultured at 25°C, and Aspergillus flavus and Aspergillus niger were cultured at 28°C. All of the above were cultured under weak light conditions for 7 days. Then, bacterial suspensions were prepared with sterile saline and the concentration of the bacterial suspensions was adjusted to about 1×10 7 CFU / mL.

[0161] Serial dilution of CeCACs, CeCA, CeCAGa, and tebuconazole was performed in 96-well plates using culture medium to obtain gradient concentrations of the samples: 1500, 750, 375, 187.5, 93.7, 46.8, 23.4, 11.7 μg / mL, with 3 replicates for each concentration.

[0162] Inoculation of bacterial suspension: An appropriate amount of bacterial suspension was added to each well to make the final bacterial suspension concentration 1×10 5 CFU / mL. At the same time, growth control wells without samples and blank control wells without bacterial suspension were set up.

[0163] Seal the 96-well plates and incubate at an appropriate temperature. Fusarium oxysporum and Fusarium solani are generally incubated at 25°C, and Aspergillus flavus and Aspergillus niger are incubated at 28°C for 48 hours.

[0164] After incubation, use a microplate reader to measure the absorbance (OD value) of each well. Taking the OD value of the growth control well as a reference, judge the inhibitory effect of the drug on fungal growth.

[0165] Record the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of each group.

[0166] 3. Result analysis

[0167] The MIC and MFC of each group are shown in Table 2.

[0168] From the data comparison of #1 and #2, #3 in Table 2, it can be seen that the MIC of CeCACs prepared in the present invention against Fusarium oxysporum, Fusarium solani, Aspergillus flavus, and Aspergillus niger are 46.8, 46.8, 93.7, 46.8 μg / mL respectively, which are significantly less than those of CeCA and CeCAGa, showing its better inhibitory effect; from the data comparison of #1 and #4, the minimum inhibitory concentration of CeCACs of the present invention is also significantly less than that of tebuconazole.

[0169] The reason may be that the antifungal effect of CA plays a role through multiple mechanisms, including disrupting the plasma membrane, inhibiting ergosterol biosynthesis, reducing mitochondrial membrane potential, and generating excessive reactive oxygen species (ROS), ultimately leading to cell death similar to apoptosis. The significant antifungal efficacy of CeCACs may stem from the synergistic effect between CA and chitosan (Cs). Positively charged chitosan enhances the binding to the negatively charged fungal cell surface, thereby enhancing the overall antifungal effect of the compound. Chitosan affects the regulation of genes related to cell wall and membrane homeostasis, resulting in cell wall proliferation and structural strengthening.

[0170] Table 2 MIC and MFC concentrations of each group (μg / mL)

[0171]

[0172] IV. Packaging Material Test

[0173] 1. Sample Description

[0174] Peanut seeds, purchased from the market.

[0175] CeCACs was prepared according to Example 3; CeCAGa was prepared according to Comparative Example 2; carboxymethyl cellulose (CMC), with a concentration of 0.5%, was purchased from the market; tebuconazole suspension, with an active ingredient of 430 g / L, was purchased from the market.

[0176] 2. Test Procedure

[0177] For peanut seeds, plump, intact, and not contaminated by fungi were selected and divided into 4 groups, with 20 seeds (about 26 g) in each group; the first group (#1) used 0.5% CMC containing 100 μg / mL CeCACs as the packaging material to treat the seeds; the second group (#2) used 0.5% CMC containing 100 μg / mL CeCAGa as the packaging material to treat the seeds; the third group (#3) used 0.5% CMC containing 100 μg / mL tebuconazole suspension as the packaging material to treat the seeds; the fourth group (#4) used 0.5% CMC as the packaging material; the fifth group (#5) was treated without packaging material.

[0178] The peanut seeds of each group were added to the packaging material, stirred evenly, fished out and dried, then sown on a seedbed with perlite and peat soil as the mixed substrate, and then covered with a thin layer of soil; the growth of peanut seeds in each group was observed 12 days after sowing, and the germination rate, seedling length, root length, and fresh weight of each group were measured and recorded with a ruler and a balance, and the average value was taken.

[0179] It can be seen from the data in Table 4 that each group had a good germination rate, and the treatment with the packaging material did not have an adverse effect on the germination and growth of peanut seeds. The germination rate, seedling length, root length, and fresh weight of the CeCACs group were better than those of other groups after treatment. The reason may be the pretreatment effect of the seeds. In the initial hydration stage of pretreatment, the seeds will produce stress memory and enhance their adaptability to the subsequent growth stage.

[0180] The seedlings coated only with carboxymethyl cellulose (CMC) and the seedlings treated with the CeCACs group showed slightly enhanced growth and vitality compared with the seedlings of the control group and the tebuconazole group. This may be because CMC provided additional carbon for the seedlings; the growth of the CeCAGa group was weaker than that of the CMC group and the CeCACs group. This may be because after the packaging material treatment and planting, the rapid dissolution of arabic gum after the decomposition of chitosan caused the exposure and volatilization of cinnamaldehyde, which affected the absorption of the seedlings; while the CeCACs group had a more significant positive effect on the growth of the seedlings, which may be due to the slow release effect that made CA gradually release and promoted the growth of beneficial bacteria in the seedlings.

[0181] Table 4 Growth of peanut seeds in each group treated with packaging materials

[0182] Number Germination rate / % Seedling length / cm Root length / cm Fresh weight / g #1 100％ 10.94 20.19 5.37 #2 90％ 10.75 19.63 5.22 #3 95％ 10.52 19.61 5.04 #4 85％ 10.70 19.43 5.30 #5 85％ 10.39 18.99 5.16

[0183] 5. Fumigation test

[0184] 1. Sample Description

[0185] Aspergillus flavus and Fusarium oxysporum were from strains stored in the Guangxi Zhuang Autonomous Region Subtropical Crops Research Institute; peanut seeds were purchased commercially; Qinmi No. 9 passion fruit was purchased commercially.

[0186] CeCACs was prepared by Example 3 of the present invention, and CeCAGa was prepared by Comparative Example 2; Tebuconazole suspension, with an active ingredient of 430 g / L, was commercially available.

[0187] 2. Experimental process

[0188] Peanut seeds used a 90 mm culture dish (volume 126 mL) as a fumigation container. According to the minimum inhibitory concentration (MIC) and the volume of the fumigation container, the dosage of each antifungal agent for peanut fumigation was calculated as follows: CeCACs was 5.9 mg, CeCAGa was 23.6 mg, and tebuconazole suspension was 11.8 mg.

[0189] Peanut seeds that were plump, intact, and not contaminated by fungi were selected and divided into three groups, with four portions in each group and 15 seeds (about 16 g) in each portion. The peanut seeds in each group were first disinfected with 75% ethanol and then coated with 0.5% CMC (1×10 5 spores / mL) and dried at room temperature; then the peanut seeds were arranged on the edge of a 90 mm culture dish, and different amounts of antifungal agents were placed in a 60 mm culture dish in the center of the culture dish; wherein the antifungal agent of the first group (1#) was CeCACs, and the dosages of the four portions were 20 mg, 10 mg, 5 mg, and 0 mg respectively (control); the antifungal agent of the second group (2#) was CeCAGa, and the dosages of the four portions were 20 mg, 10 mg, 5 mg, and 0 mg respectively (control); the antifungal agent of the third group (3#) was tebuconazole, and the dosages of the four portions were 20 mg, 10 mg, 5 mg, and 0 mg respectively (control); each control group used a culture dish without antifungal agent instead of the antifungal agent.

[0190] The petri dishes were sealed with transparent tape and incubated at 25 °C for 7 days. After this period, the 60 mm petri dishes containing the antifungal agent were replaced with petri dishes containing water, and incubation was continued for 7 days; this operation was to simulate the humid conditions in an adverse storage environment. After the incubation period, the peanut seeds in each group were transferred to potato dextrose agar (PDA) plates to evaluate the survival rate of the coated spores. At the same time, the peanuts were shaken in a 0.01% Tween-80 solution to collect the spores, and then the spores were spread on 1% malt extract agar. After 24 h of plate incubation, the number of spores producing fungal colonies was counted and expressed as the spore yield per gram of peanuts.

[0191] For passion fruits, 641 mL plastic containers with lids were used as fumigation containers. According to the minimum inhibitory concentration (MIC) and the volume of the fumigation containers, the dosages of each antifungal agent for passion fruit fumigation were calculated as follows: 30 mg of CeCACs, 60.7 mg of CeCAGa; 60.7 mg of tebuconazole suspension.

[0192] Fresh, intact, and healthy passion fruit fruits were collected, surface disinfected with 75% ethanol, and then wiped with sterilized distilled water; then they were evenly divided into 3 groups, with 4 fruits in each group, each about 60 g. The fruits in each group were placed in the corresponding plastic containers, and freshly harvested Fusarium oxysporum spores were inoculated at a concentration of 1×10 5 spores / mL; different amounts of antifungal agents were added to the containers: the antifungal agent for the first group was CeCACs, and the dosages for the 4 portions were 120 mg, 60 mg, 30 mg, and 0 mg (control); the antifungal agent for the second group was CeCAGa, and the dosages for the 4 portions were 120 mg, 60 mg, 30 mg, and 0 mg (control); the antifungal agent for the third group was tebuconazole, and the dosages for the 4 portions were 120 mg, 60 mg, 30 mg, and 0 mg (control); after sealing, they were incubated at 25 °C for 7 h, and after incubation, the average lesion diameter of the fruits in each group was measured with a ruler.

[0193] 3. Result analysis

[0194] As can be seen from the data in Table 4 below, when the dosage was 20 mg in the first group, the second group, and the third group, the spore amount was 0, indicating that the inhibitory effect at a relatively high concentration was obvious; when the dosage was 10 mg, the spore amount after treating peanut seeds in the first group was 0 spores / g, and those in the second group and the third group were 0.5×10 5 spores / g and 0.5×10 5 spores / g respectively; when the dosage was 5 mg, the spore amount after treating peanut seeds in the first group was 4.3×10 5 spores / g, and those in the second group and the third group were 5.1×10 5 spores / g and 6.7×10 5per / g; It can be seen that under the same concentration, the antibacterial performance of the CeCACs of the present invention is superior to that of CeCAGa and tebuconazole, indicating that it has good antifungal potential as a fumigant.

[0195] Table 4 Spore quantity results of the peanut seed experimental group

[0196]

[0197] From the data in Table 5 below, it can be seen that in the first group, the second group, and the third group, when the dosage was 60 mg, the spore quantity was 0, indicating that the antibacterial effect at a relatively high concentration was obvious; while when the dosage was 30 mg, the lesion diameter of the passion fruits in the first group was 1.5 cm, while those in the second group and the third group were 2.7 cm and 3.1 cm respectively; It can be seen that under the same concentration, the antibacterial performance of the CeCACs of the present invention is superior to that of CeCAGa and tebuconazole, and it can be used as a fumigant for fruit storage.

[0198] Table 5 Lesion diameter results of the passion fruit experimental group

[0199]

[0200] Therefore, from the above antifungal tests, through the data comparison of the CeCACs of the present invention with CeCAGa and tebuconazole, it can be known that the CeCACs have better antifungal performance, have better antibacterial effects on Fusarium oxysporum, Aspergillus flavus, Aspergillus niger, and Fusarium solani, are superior to CeCAGa, and are superior to the antifungal agent tebuconazole used in the market.

[0201] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising a..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the element.

Claims

1. A biodegradable antifungal composition, characterized in that The cinnamaldehyde is loaded on cellulose and then encapsulated by chitosan coating to prepare the antifungal composition (CeCACs).

2. A biodegradable antifungal composition according to claim 1, characterized in that: The loading content of cinnamaldehyde is 40%-85%.

3. A biodegradable antifungal composition according to claim 2, characterized in that: The antifungal composition is used at a concentration of 40-115 μg / mL.

4. A biodegradable antifungal composition according to claim 3, characterized in that: Cellulose is prepared by the following method: S1, softening treatment: the mushroom residue is made into powder, suspended in water, soaked, filtered, the residue obtained is soaked in sodium hydroxide solution, and then filtered to obtain a softened product; S2, acid hydrolysis: the softened product is washed to neutrality, resuspended in acetic acid, heated at 70-100°C, filtered, and a hydrolyzate is obtained; S3, alkali treatment: the hydrolyzate is added to a mixed solution containing hydrogen peroxide and sodium hydroxide, heated at 75-100°C, and filtered to obtain an alkali-treated product; S4, bleaching treatment: the alkali-treated product is washed, dispersed in a sodium hypochlorite solution at 60-85°C for bleaching, filtered, and further bleached with a hydrogen peroxide solution at 65-80°C, filtered, and a bleached product is obtained; S5. Ultrasonic treatment: adding the bleached product into a mixed solution of nitric acid and hydrogen peroxide, ultrasonically treating the product to separate dense and clearly dispersed fibers from the solution, then washing the fibers to neutrality, filtering the fibers, and obtaining the product.

5. A method for preparing a biodegradable antifungal composition, characterized in that: The following steps are involved: S6, preparing a cellulose suspension, adding the suspension to an ethanol solution of cinnamaldehyde, stirring evenly, filtering, and washing the precipitate to obtain cinnamaldehyde-cured cellulose (CACs); S7, adding cinnamaldehyde solidified cellulose to the chitosan solution, stirring evenly, filtering when the cinnamaldehyde solidified cellulose turns yellow, washing the precipitate, and air-drying to a fixed weight to obtain the antifungal composition (CeCACs).

6. A method for preparing a biodegradable antifungal composition according to any one of claims 1 to 5, characterized in that: In step S6, the concentration of the cellulose suspension is 5-15%; the volume ratio of cellulose mass to cinnamaldehyde is 0.67-2 g / mL.

7. The method for preparing a biodegradable antifungal composition according to claim 6, characterized in that: In step S7, the concentration of the chitosan solution is 0.5-2%, and the volume ratio of the mass of cinnamaldehyde-cured cellulose to chitosan is 0.06-0.2 g / mL.

8. The use of a biodegradable antifungal composition according to claim 8, characterized in that: Using the antifungal composition according to any one of claims 1 to 7 as a fumigant for fumigating plant fruits before storage; The concentration of CeCACs in the fumigated area was 40-100 μg / mL.

9. Use of a biodegradable antifungal composition, characterized in that: Using the antifungal composition according to any one of claims 1 to 7 as a packaging material for preparing seed coating; The packaging material also contains carboxymethyl cellulose at a concentration of 0.3-0.8%; CeCACs concentration was 85-110 μg / mL; The amount of packaging material used is 5-20g / kg.

10. The use of a biodegradable antifungal composition according to claim 8, characterized in that: The antifungal composition according to any one of claims 1 to 7 is used as a soil conditioner in an amount of 15-40 g / m 2 .

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