Preparation method and application of carbon nanodots for preventing and treating wheat diseases

Abstract

The invention relates to the related technical field of wheat disease prevention and control, in particular to a preparation method and application of carbon nanodots for wheat disease prevention and control, semen cassiae is used as a precursor, ethyl alcohol is used as a reaction solvent, the semen cassiae and the ethyl alcohol are mixed according to the mass ratio of 1: 2-1: 10 to obtain a mixed precursor, then the mixed precursor is placed in a reaction kettle to be sealed, and the carbon nanodots are prepared at the heating temperature of 140-180 DEG C for 1-2 h. The preparation method comprises the following steps: adding carbon nanodots into a reaction kettle, reacting for 2-8 hours, filtering the reacted solution to remove reaction residues, reserving the solution, putting the solution into a drying box, drying at 60 DEG C to obtain powder, re-dispersing the dried powder by using deionized water, dialyzing by using a dialysis bag with the molecular weight of 500 for 12 hours, and freeze-drying a sample by using a freeze-drying machine to obtain the carbon nanodot powder capable of being used for preventing and treating wheat diseases. The carbon nanodots can effectively generate active oxygen under excitation of visible light, disease fungi can be killed through a photophysical process, generation of drug resistance can be reduced to the maximum extent, and the disease incidence rate of wheat in the field can be effectively reduced by spraying the carbon nanodot solution to wheat.

Description

A method for preparing carbon nanodots for wheat disease control and its application Technical Field

[0001] This invention relates to the technical field of wheat disease control, and in particular to a method for preparing and applying carbon nanodots for wheat disease control. Background Technology

[0002] Wheat is a vital staple crop in my country, and Henan Province, as the largest wheat-producing area in the country, accounts for more than a quarter of the national output, playing a crucial role in ensuring national food security. However, in recent years, wheat scab, caused by Fusarium, has become increasingly prevalent, leading to ear rot and shriveled grains. This not only causes severe yield reduction but also threatens human and animal health due to fungal toxin contamination, becoming a major bottleneck restricting the sustainable development of the wheat industry. Currently, my country's control of fungal diseases such as wheat scab still mainly relies on chemical pesticides. Although this method is effective quickly, it has many increasingly prominent drawbacks: over-reliance on chemical control leads to increasing pesticide resistance in pathogens; excessive use not only increases production costs but also damages the farmland ecological environment, affecting soil health and biodiversity; furthermore, pesticide residues directly threaten food quality and consumer health. Therefore, developing green, efficient, and pesticide-free novel antimicrobial control technologies has become an urgent task.

[0003] Photodynamic sterilization, as a green and highly efficient novel antibacterial technology, has shown broad application prospects in the field of sterilization in recent years. Its principle is based on the use of photosensitizers to generate reactive oxygen species (such as singlet oxygen and hydroxyl radicals) under specific wavelengths of light excitation, thereby causing irreversible damage to the cell membranes, proteins, and nucleic acids of pathogenic microorganisms, ultimately achieving highly efficient sterilization. Compared with traditional chemical pesticides, photodynamic sterilization has significant advantages such as high efficiency, environmental friendliness, no pesticide residues, and low likelihood of inducing drug resistance, making it highly compatible with the current strategic direction of sustainable agricultural development.

[0004] Carbon nanodots, as a novel photosensitive material, possess numerous advantages, such as abundant precursors, low manufacturing cost, and tunable photoelectron transfer capabilities, making them an ideal candidate for new photosensitive materials. However, most carbon nanodots exhibit significant effects on bacteria but limited efficacy against fungi, thus restricting their application in the control of wheat scab. Therefore, there is an urgent need to develop carbon nanodot materials that are visible light responsive, have strong binding affinity to pathogenic fungi, and produce high levels of reactive oxygen species, providing new avenues for combating wheat fungal diseases. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing carbon nanodots for the prevention and control of wheat diseases, and to solve the problem that most carbon nanodots in the prior art have significant effects on bacteria but limited effects on fungi, thus limiting their application in the prevention and control of wheat scab.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing carbon nanodots for wheat disease control, comprising the following steps:

[0007] Step S1: Using cassia seeds as a precursor and ethanol as a reaction solvent, mix the two in a mass ratio of 1:2 to 1:10 to obtain the mixed precursor.

[0008] Step S2: Mix the precursors from step S1, place them in a sealed reactor, and react at a heating temperature of 140℃-180℃ for 2-8 hours.

[0009] Step S3: Filter the solution after the reaction to remove the reaction residue, keep the solution, and then put it in a drying oven to dry at 60°C to obtain powder;

[0010] Step S4: The dried powder is redispersed with deionized water, dialyzed with a dialysis bag with a molecular weight of 500 for 12 hours, and then freeze-dried using a freeze dryer to obtain carbon nanoparticle powder that can be used for the prevention and control of wheat diseases.

[0011] Preferably, the ethanol in step S1 is anhydrous ethanol, 95% ethanol, or 75% ethanol.

[0012] Preferably, the carbon nanoparticle powder has an average particle size of 3.4 nanometers.

[0013] Preferably, the carbon nanodots can generate reactive oxygen species (hydroxyl radicals, superoxide anions, and singlet oxygen) under visible light excitation.

[0014] An application of carbon nanodots for the prevention and control of wheat diseases, wherein the wheat fungal disease is Fusarium head blight caused by Fusarium graminearum.

[0015] Preferably, the application method is as follows: the carbon nanodots are prepared into an aqueous solution and sprayed onto wheat plants, and activated by natural light or artificial visible light (natural light is used in field experiments; artificial visible light is used in laboratory sterilization experiments, with simulated sunlight generated by an Xe lamp light source and an AM1.5 filter) to achieve photodynamic sterilization.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] 1. Using cassia seeds as a carbon source precursor, its unique biomass components form carbon nanodots with high targeting specificity to fungal cell structures during the carbonization process. These carbon nanodots can not only be efficiently excited by visible light to generate reactive oxygen species, but also effectively penetrate and destroy the cell wall and cell membrane of Fusarium graminearum, thereby significantly improving the control effect against wheat scab and successfully overcoming the technical bottleneck of poor inhibition effect of existing carbon nanodot materials against fungal diseases.

[0018] 2. This carbon nanodot solution can effectively kill Fusarium graminearum (the main pathogenic fungus of Fusarium head blight) under sunlight. When sprayed on wheat, it can effectively reduce the incidence of wheat diseases in the field. Attached Figure Description

[0019] Figure 1 is a transmission electron microscope image of the carbon nanodots of the present invention;

[0020] Figure 2 is an X-ray photoelectron spectrum of the carbon nanodots of the present invention;

[0021] Figure 3 shows the types of reactive oxygen species in carbon nanodots under visible light excitation using EPR according to the present invention.

[0022] Figure 4 shows the performance of singlet oxygen generation from carbon nanodots detected by the singlet oxygen probe in this invention.

[0023] Figure 5 shows the bactericidal performance of the carbon nanodots of the present invention against Fusarium graminearum;

[0024] Figure 6 shows the results of the control of wheat scab by carbon nanodots of the present invention in the field. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Please refer to Figures 1-6. This invention provides a technical solution: a method for preparing carbon nanodots for wheat disease control, comprising the following steps:

[0027] Step S1: Using cassia seeds as a precursor and ethanol as a reaction solvent, mix the two in a mass ratio of 1:2 to 1:10 to obtain the mixed precursor.

[0028] Step S2: Mix the precursors from step S1, place them in a sealed reactor, and react at a heating temperature of 140℃-180℃ for 2-8 hours.

[0029] Step S3: Filter the solution after the reaction to remove the reaction residue, keep the solution, and then put it in a drying oven to dry at 60°C to obtain powder;

[0030] Step S4: The dried powder is redispersed with deionized water, dialyzed with a dialysis bag with a molecular weight of 500 for 12 hours, and then freeze-dried using a freeze dryer to obtain carbon nanoparticle powder that can be used for the prevention and control of wheat diseases.

[0031] Furthermore, in step S1, the ethanol is: anhydrous ethanol, 95% ethanol, or 75% ethanol.

[0032] Furthermore, the average particle size of the carbon nanodot powder is 3.4 nanometers.

[0033] Furthermore, carbon nanodots can generate reactive oxygen species (hydroxyl radicals, superoxide anions, and singlet oxygen) when excited by visible light.

[0034] An application of carbon nanodots for the prevention and control of wheat diseases, specifically Fusarium head blight caused by Fusarium graminearum.

[0035] Furthermore, the application method is as follows: carbon nanodots are prepared into an aqueous solution and sprayed onto wheat plants. They are then activated by natural light or artificial visible light (natural light is used in field experiments; artificial visible light is used in laboratory sterilization experiments, with simulated sunlight generated by an Xe lamp source and an AM1.5 filter) to achieve photodynamic sterilization.

[0036] Example 1

[0037] This implementation example provides a method for preparing carbon nanodot materials for wheat disease control, including the following steps:

[0038] (1) Cassia seed is used as a precursor and ethanol is used as a reaction solvent, with a mass ratio of 1:2;

[0039] (2) Mix the precursors from step (1), place them in a reaction vessel and seal it, then place it in a drying oven and heat it to 140°C for 2 hours;

[0040] (3) Filter the solution after the reaction to remove the reaction residue, keep the solution, and dry it at 60°C to obtain powder;

[0041] (4) The dried powder was redispersed with deionized water and dialyzed for 12 hours using a dialysis bag with a molecular weight of 500. Then the sample was freeze-dried to obtain carbon nanoparticle powder that can be used for the prevention and control of wheat diseases.

[0042] Example 2

[0043] This embodiment provides a method for preparing carbon nanodot materials for wheat disease control, which is basically the same as the steps in Example 1, except that: the mass ratio of the precursor cassia seed to the reaction solvent ethanol is 1:5; in step (2), the reaction temperature is heated to 160°C and the reaction time is 4 hours; in step (3), the solution after the reaction is filtered to remove the reaction residue, and the solution is centrifuged to further remove impurities, and finally the supernatant is dried at 60°C to obtain powder; in step (4), the sample is dialyzed for 12 hours using a dialysis bag with a molecular weight of 500. Then, the sample is freeze-dried using a freeze dryer to obtain carbon nanodot powder that can be used for wheat disease control.

[0044] Example 3

[0045] This embodiment provides a method for preparing carbon nanodot materials for wheat disease control, which is basically the same as the steps in Example 1, except that: the precursor solution is replaced with 95% ethanol instead of anhydrous ethanol, and the mass ratio of the precursor cassia seed to the reaction solvent ethanol is 1:10; in step (2), the reaction temperature is heated to 180°C and the reaction time is 6 hours; the remaining steps are the same as in Example 1.

[0046] Example 4

[0047] This embodiment provides a method for preparing carbon nanodot materials for wheat disease control, which is basically the same as the steps in Example 1, except that: the precursor solution is replaced with 75% ethanol instead of anhydrous ethanol, and the mass ratio of the precursor cassia seed to the reaction solvent ethanol is 1:10; in step (2), the reaction temperature is heated to 180°C and the reaction time is 8 hours; the remaining steps are the same as in Example 1.

[0048] Example 5

[0049] This embodiment provides a method for preparing carbon nanodot materials for wheat disease control, which is basically the same as the steps in Example 1, except that: the mass ratio of the precursor cassia seed and the reaction solvent anhydrous ethanol is 1:5; in step (2), the heating reaction temperature is 160°C and the reaction time is 8 hours; the remaining steps are the same as in Example 1.

[0050] Example 6

[0051] This embodiment provides a method for applying the above-mentioned carbon nanodot material in the prevention and control of wheat scab:

[0052] (1) The carbon nanoparticle powder prepared in Example 1 was prepared into suspensions with concentrations of 0.05 mg / mL, 0.1 mg / mL and 0.3 mg / mL using deionized water, and ultrasonically treated for 20 minutes to make it uniformly dispersed; Fusarium graminearum spore suspension (concentration of about 10^6 CFU / mL) was prepared, and Fusarium graminearum spore suspension was artificially added to wheat ears (200 μL / ear) at the early flowering stage of wheat to create artificially infected wheat ears, with about 50-80 plants in each group of infected wheat ears.

[0053] (2) At the early flowering stage of wheat, a handheld sprayer was used to spray the carbon nanodot solution evenly onto the wheat ears and upper leaves, with a spraying amount of about 15 liters per mu; the blank control group was sprayed with an equal amount of aqueous solution without carbon dots.

[0054] (3) After spraying, carbon nanoparticles are activated by natural sunlight, and the daily sunlight exposure time is not less than 6 hours;

[0055] (4) Spraying once every 7 days for 3 consecutive times can significantly reduce the infection rate of Fusarium graminearum.

[0056] Example 7

[0057] This embodiment verifies the bactericidal performance of carbon nanodots under artificial light:

[0058] (1) Inoculate Fusarium graminearum onto PDA plates to prepare a bacterial suspension (concentration of approximately 10^6 CFU / mL).

[0059] (2) Add the carbon nanodot solution prepared in Example 2 to each solution, so that the final concentration is between 0.05 mg / mL and 0.6 mg / mL;

[0060] (3) Use a 300 W xenon lamp equipped with an AM 1.5 filter to simulate sunlight. The light intensity is 3000 lux and the light exposure time is 30 minutes. During the light exposure, the sample is placed in an ice-water bath to eliminate the influence of temperature on the sterilization results.

[0061] (4) After the light exposure ended, the carbon nanodots were spread on a plate and cultured for 48 hours. The colony growth was observed, which confirmed that carbon nanodots have a significant photodynamic bactericidal effect.

[0062] As shown in Figure 1, the average particle size of the carbon nanodots is 3.4 nm. Figure 2 shows the X-ray photoelectron spectrum of the carbon nanodots, indicating that the main elemental components are carbon, oxygen, and nitrogen. Figure 3 uses electron paramagnetic resonance (EPR) combined with a trapping agent to detect the reactive oxygen generation performance of carbon nanodots under visible light excitation. Figure 4 shows the performance of carbon nanodots in generating singlet oxygen using a green fluorescent probe. Figure 5 shows the photodynamic killing performance of the carbon nanodots against Fusarium graminearum, indicating that under light conditions, the carbon nanodots effectively kill the main pathogen of wheat scab. Figure 6 shows the effect of carbon nanodots on the control of scab in the field after applying the carbon nanodots during the wheat flowering stage. Corresponding images were collected after 14 and 21 days. As the concentration of carbon nanodots gradually increased, the disease incidence in wheat ears gradually decreased.

[0063] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing carbon nanodots for wheat disease control, characterized in that, Includes the following steps: Step S1: Using cassia seeds as a precursor and ethanol as a reaction solvent, mix the two at a mass ratio of 1:2 to 1:10 to obtain a mixed precursor. Step S2: Mix the precursors from Step S1, place them in a reaction vessel and seal it. React at a heating temperature of 140℃-180℃ for 2-8 hours. Step S3: Filter the solution after the reaction to remove reaction residues, retain the solution, and then place it in a drying oven to dry at 60℃ to obtain powder. Step S4: Redisperse the dried powder with deionized water, dialyze it with a dialysis bag with a molecular weight of 500 for 12 hours, and then freeze-dry the sample using a freeze dryer to obtain carbon nanoparticle powder that can be used for the prevention and control of wheat diseases.

2. The method for preparing carbon nanodots for wheat disease control according to claim 1, characterized in that, The ethanol in step S1 is: anhydrous ethanol, 95% ethanol, or 75% ethanol.

3. The method for preparing carbon nanodots for wheat disease control according to claim 1, characterized in that, The average particle size of the carbon nanodot powder is 3.4 nanometers.

4. The method for preparing carbon nanodots for wheat disease control according to claim 1, characterized in that, The carbon nanodots can generate reactive oxygen species (hydroxyl radicals, superoxide anions, and singlet oxygen) when excited by visible light.

5. An application of carbon nanodots for wheat disease control, as described in any one of claims 1-4, characterized in that... The fungal disease of wheat mentioned is Fusarium head blight caused by Fusarium graminearum.

6. The application of carbon nanodots for wheat disease control according to claim 5, characterized in that, The application method is as follows: the carbon nanodots are prepared into an aqueous solution and sprayed onto wheat plants, and activated by natural light or artificial visible light to achieve photodynamic sterilization.

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