Application of curcumin carbon nanodots in the prevention and treatment of wheat scab

Abstract

This invention discloses the application of turmeric carbon nanodots in the control of wheat scab. The application of turmeric carbon nanodots in the control of wheat scab was carried out under natural light irradiation conditions. The turmeric carbon nanodots were prepared by a method comprising the following steps: 1) taking turmeric powder and drying it for later use; 2) subjecting the system of the turmeric powder and solvent to a hydrothermal reaction, centrifuging after the reaction, and collecting the supernatant; 3) purifying the supernatant and drying it to obtain the turmeric carbon nanodots. This invention uses the naturally occurring herbaceous plant turmeric as a precursor and combines it with carbon nanodot technology to prepare turmeric CDs. Turmeric is widely available and easy to obtain. The prepared turmeric CDs have excellent antibacterial ability against Fusarium graminearum spores and a good control effect on wheat scab, without adversely affecting the growth of wheat seedlings. It is expected to be an ideal agricultural green fungicide with great market application prospects.

Description

Technical Field

[0001] This invention belongs to the field of pesticide technology, and in particular relates to the application of carbon nanodots in the control of wheat scab. Background Technology

[0002] Fusarium head blight, a fungal disease caused by Fusarium graminearum, poses a serious threat to global food security and human and animal health. Commonly used methods for controlling Fusarium head blight involve spraying pesticides, which are highly toxic. To avoid pesticide residues, ensure food security, and address the shortcomings of traditional Fusarium head blight control technologies—such as slow effectiveness of agricultural control, difficulty in breeding resistant varieties, and environmental pollution and increased pathogen resistance from long-term use of chemical reagents—there is an urgent need to develop highly efficient, environmentally friendly new green pesticides to replace existing commercially available varieties.

[0003] Carbon nanodots (CDs) are newly discovered spherical carbon particles, typically smaller than 10 nm in size. They possess advantages such as a wide range of synthetic raw materials, diverse synthesis methods, high fluorescence intensity, broad fluorescence range, low biotoxicity, and good photobleaching tolerance, leading to their widespread application in fields such as biofluorescence imaging, chemical detection, biological detection, photocatalysis, and drug loading. Carbon nanodots obtained using different raw materials or preparation methods exhibit different structures, compositions, and properties, resulting in diverse applications. The preparation of carbon nanodots is broadly categorized into two types based on the raw materials: "top-down" and "bottom-up" methods. The "bottom-up" method utilizes small-sized organic molecules or oligomers (citric acid, malic acid, glucose, etc.) as raw materials, employing methods such as chemical oxidation, combustion, template formation, hydrothermal synthesis, or microwave synthesis to prepare carbon nanodots. In recent years, a "green synthesis method" has emerged within the hydrothermal synthesis approach, using natural biological resources such as bananas and lemon juice as raw materials to prepare carbon nanodots. Additionally, natural raw materials such as sweet peppers, milk, and bovine serum albumin have also been used in research on the hydrothermal preparation of carbon nanodots. Compared with traditional agricultural disease control measures, CDs can rapidly and efficiently kill a variety of bacteria and fungi, with multiple targets, making it difficult for pathogens to develop resistance. As an emerging bactericidal material, most researchers have explored the bactericidal effects and mechanisms of CDs against bacteria. However, due to the more complex structure of fungi (especially multicellular fungi), there are relatively few reports on their fungicidal effects, and there are currently no reports on the application of CDs in the control of Fusarium head blight. Summary of the Invention

[0004] The purpose of this invention is to provide the application of turmeric carbon nanodots in the control of wheat scab. These turmeric carbon nanodots (CDs) are prepared using the naturally occurring herbaceous plant turmeric as a precursor via a hydrothermal method. They exhibit excellent antibacterial activity against Fusarium graminearum spores and show good control effects against wheat scab, without adversely affecting the growth of wheat seedlings. This invention is the first to combine CDs with agricultural production, which not only meets the development requirements of "green agriculture" but also further expands the application of CDs in the agricultural field, especially in the control of wheat diseases.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides the use of turmeric carbon nanodots in any of the following or in the preparation of products having any of the following functions;

[0007] A1. Prevention and control of plant diseases caused by Fusarium graminearum;

[0008] A2. Prevention and control of wheat scab;

[0009] A3. Kills Fusarium spores;

[0010] A4. Inhibits Fusarium graminearum;

[0011] A5. Inhibits the growth of Fusarium graminearum spores;

[0012] A6. Inhibits the germination of Fusarium graminearum spores;

[0013] The application was performed under natural light conditions.

[0014] The turmeric carbon nanodots were prepared by a method comprising the following steps:

[0015] 1) Take turmeric powder, dry it, and set it aside for later use;

[0016] 2) The reaction system consisting of the turmeric powder and solvent is subjected to a hydrothermal reaction. After the reaction is complete, the mixture is centrifuged and the supernatant is collected.

[0017] 3) The supernatant was purified and dried to obtain the turmeric carbon nanodots.

[0018] In the above applications, the solvent can be anhydrous ethanol or N,N dimethylformamide;

[0019] The temperature of the hydrothermal reaction can be 120-180℃, preferably 140-160℃, such as 160℃;

[0020] The hydrothermal reaction can take 2 to 6 hours, specifically 5 hours.

[0021] In the above applications, the ratio of turmeric powder to solvent is 1g:(4-20)mL, preferably 1g:20mL.

[0022] In the above applications, the centrifugation speed is 5000-10000 rpm and the time is 5-10 minutes, such as centrifuging at 10000 rpm for 10 minutes;

[0023] The purification was performed using silica gel column chromatography.

[0024] In the above applications, the turmeric carbon nanodots exist in the form of an aqueous solution with a concentration of 0 to 0.5 g / L, but not 0, preferably 0.01 to 0.5 g / L, more preferably 0.05 to 0.5 g / L, even more preferably 0.1 to 0.5 g / L, and most preferably 0.5 g / L.

[0025] In a second aspect, the present invention provides the use of a bactericidal composition comprising turmeric carbon nanodots in any of the following or in the preparation of a product having any of the following functions;

[0026] A1. Prevention and control of plant diseases caused by Fusarium graminearum;

[0027] A2. Prevention and control of wheat scab;

[0028] A3. Kills Fusarium spores;

[0029] A4. Inhibits Fusarium graminearum;

[0030] A5. Inhibits the growth of Fusarium graminearum spores;

[0031] A6. Inhibits the germination of Fusarium graminearum spores;

[0032] The application was performed under natural light conditions.

[0033] The turmeric carbon nanodots were prepared by a method comprising the following steps:

[0034] 1) Take turmeric powder, dry it, and set it aside for later use;

[0035] 2) The reaction system consisting of the turmeric powder and solvent is subjected to a hydrothermal reaction. After the reaction is complete, the mixture is centrifuged and the supernatant is collected.

[0036] 3) The supernatant was purified and dried to obtain the turmeric carbon nanodots.

[0037] In the above applications, the solvent is anhydrous ethanol or N,N dimethylformamide;

[0038] The temperature of the hydrothermal reaction can be 120-180℃, preferably 140-160℃, such as 160℃;

[0039] The hydrothermal reaction can take 2 to 6 hours, specifically 5 hours.

[0040] In the above applications, the ratio of turmeric powder to solvent can be 1g:(4-20)mL, specifically 1g:20mL;

[0041] The centrifugation speed is 5000-10000 rpm, and the time is 5-10 minutes, such as centrifuging at 10000 rpm for 10 minutes;

[0042] The purification was performed using silica gel column chromatography.

[0043] In the above applications, the bactericidal composition further includes excipients and / or bactericidal components that can be compounded with the turmeric carbon nanodots.

[0044] The natural light exposure mentioned in any of the above items can specifically refer to natural light exposure on a sunny day.

[0045] The Fusarium graminearum mentioned above can specifically refer to the standard wild-type strain of Fusarium graminearum, PH-1.

[0046] The products described above may be agricultural fungicides or compound agricultural fungicides. The formulation of the agricultural fungicide or compound agricultural fungicide is not limited, and may include any one of the following: suspension concentrate, wettable powder, emulsifiable concentrate, water-dispersible granules, microemulsion, water-in-oil emulsion, suspension concentrate, and microcapsule suspension.

[0047] The present invention has the following beneficial effects:

[0048] The mechanism of action of this invention is as follows: Turmeric CDs can utilize photocatalysis to convert natural light energy resources into ROS. Through multiple ROS and their synergistic effects, turmeric CDs can quickly and efficiently kill Fusarium graminearum. On the other hand, the multiple ROS produced by turmeric CDs can promote the growth of wheat plants and increase wheat yield to a certain extent.

[0049] This invention utilizes a hydrothermal method with naturally occurring turmeric as a precursor, combined with carbon nanodot technology, to prepare turmeric CDs through a series of physicochemical methods. These turmeric CDs exhibit excellent photoelectron conversion performance, good chemical stability and biocompatibility, low cytotoxicity, and are economical and easy to prepare. Furthermore, turmeric is widely available and readily accessible. The prepared turmeric CDs demonstrate excellent antibacterial activity against Fusarium graminearum spores, showing good control of wheat scab in the field without adversely affecting wheat seedling growth. Therefore, they hold great promise as an ideal green agricultural fungicide with significant market application potential. Attached Figure Description

[0050] Figure 1Material properties characterization of the turmeric CD prepared in Example 1: (A) Transmission electron microscope image; (B) Fourier transform infrared spectrum; (CF) X-ray photoelectron spectrum and sub-spectral images of C, N, and O corresponding to the spectral peaks.

[0051] Figure 2 The particle size distribution of turmeric CDs prepared in Example 1 is shown in the statistical diagram.

[0052] Figure 3 The effect of turmeric CDs on the survival rate of Fusarium graminearum spores under different light conditions in Example 2: (A) dark treatment; (B) natural light irradiation on sunny days.

[0053] Figure 4 To investigate the effects of turmeric CDs and their corresponding concentrations of curcumin on the spore viability of Fusarium graminearum in Example 2 after treatment for 30 minutes under different light conditions (dark treatment and natural light irradiation on sunny days): (A) Turmeric CDs treatment group; (B) Curcumin treatment group with the same concentration.

[0054] Figure 5 The effect of turmeric CDs on the growth of Fusarium graminearum in Example 3: (A) Photograph of mycelial growth; (B) Microscopic image of spore germination; (C) Mycelial growth inhibition rate; (D) Spore germination rate.

[0055] Figure 6 The images show the diseased wheat ears after treatment with different concentrations of turmeric CDs in Example 4.

[0056] Figure 7 The effects of turmeric CDs on wheat seedling growth in Example 5: (A) Photograph of wheat after 14 days of growth; (B) Plant height; (C) Fresh weight; (D) Dry weight; (E) Chlorophyll content; (F) SOD activity; (G) Changes in POD activity. Detailed Implementation

[0057] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0058] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified. All quantitative experiments in the following examples were performed in triplicate, and the results were averaged.

[0059] The turmeric used in the following examples was purchased from the medicinal herb market, and turmeric blocks of good quality were selected.

[0060] The Fusarium graminearum strain used in the following examples is the standard wild-type strain PH-1 (Li et al., 2017), which was provided by an associate researcher in our laboratory and is described in “Li,B.,Liu,L.,Li,Y.,et al.(2017).The fgvps39-fgvam7-fgsso1 complex mediates vesicle trafficking and is important for the development and virulence of fusarium graminearum.Molecular plant-microbe interactions:MPMI,30(5),MPMI11160242R.”, which is available to the public from Zhengzhou University.

[0061] Example 1: Preparation of turmeric CDs

[0062] Turmeric blocks were ground into powder. The turmeric powder was dried in a drying oven for 24 hours. 1 g of turmeric powder was weighed and placed in a reaction vessel, followed by the addition of 20 mL of anhydrous ethanol. The mixture was stirred thoroughly and then placed in a heating oven at 160°C for 5 hours. After the reaction temperature dropped to room temperature, the resulting suspension was transferred to a 50 mL test tube and centrifuged at 10,000 rpm for 10 minutes. The supernatant was collected to remove large particulate impurities. The resulting crude turmeric carbon dot solution was then purified by silica gel column chromatography to obtain a pure carbon dot solution. This purified solution was dried in an oven until the solvent completely evaporated and then stored at 25°C for later use. Characterization results are shown below. Figure 1 See the particle size distribution chart. Figure 2 In this embodiment, turmeric CDs were successfully prepared with an average particle size of 2.71 nm.

[0063] Example 2: Evaluation of the killing effect of turmeric CDs on Fusarium graminearum spores

[0064] Experimental Methods: The plate count method was used to evaluate the bactericidal effect of turmeric CDs aqueous solution on Fusarium graminearum spores. Fusarium graminearum frozen at -80℃ was activated on fresh potato dextrose agar (PDA) solid medium, cultured at 28℃ in the dark for 3 days, and then stored at 4℃ for later use.

[0065] Before each experiment, a section of the colony was cut from the edge and transferred to 100 ml of sodium carboxymethyl cellulose (CMC) liquid medium, and cultured at 28°C and 180 rpm for 5 days. After filtering the culture with sterile filter cloth, the culture was centrifuged at 6000 rpm for 10 min, and the spores were washed twice with sterile water, resuspended, and used for later use.

[0066] For the bactericidal test of turmeric CDs, the turmeric CDs solution was diluted with sterile water to concentrations of 0, 0.01, 0.05, 0.1, 0.2, 0.3, and 0.5 g / L, with 0 serving as the control group. 1.5 mL of turmeric CDs solution was transferred to a 1.5 mL centrifuge tube, and spore suspension was added. The spores were counted using a hemocytometer to achieve a final concentration of 2.7 × 10⁻⁶ spores. 5 CFU mL -1 Afterwards, the samples were placed in the dark and under natural light for 4 hours. Samples were taken after 0, 15, 30, 45, 60, 90, 180, and 240 minutes. For the sterilization test of turmeric CDs and its equivalent concentration of curcumin, the turmeric CDs solution was diluted with sterile water to concentrations of 0, 0.05, 0.1, 0.2, 0.3, and 0.5 g / L, respectively, and labeled as Control, CDs-0.05, CDs-0.1, CDs-0.2, CDs-0.3, and CDs-0.5. At the same time, the equivalent concentration of curcumin solution was labeled as Control, Cur-0.05, Cur-0.1, Cur-0.2, Cur-0.3, and Cur-0.5, respectively. Both groups of turmeric CDs and curcumin solutions were placed in 1.5 mL centrifuge tubes with the same spore concentration, and samples were taken after treatment in the dark and under light for 30 minutes.

[0067] Take 100 μL of the treated spore suspension and perform serial dilutions with sterile water. Spread each 100 μL of diluted spore suspension evenly onto a PDA solid culture dish. Incubate the PDA plates at 28°C in the dark for 36 h, then count the colonies. Spread three plates for each dilution gradient, and repeat the experiment three times.

[0068] Experimental results: The inactivation rate of turmeric CDs against Fusarium graminearum spores was as follows: Figure 3 As shown. In dark environments, turmeric CDs do not have the ability to kill Fusarium graminearum spores, see... Figure 3 (A), but as Figure 3 As shown in (B), under natural light on a sunny day, irradiation with 0.3 g / L turmeric CDs for only 30 minutes resulted in a spore concentration of 2.7 × 10⁻⁶ spores per mL. 5 CFU / mL of *Fusarium graminearum* spores were completely inactivated. Irradiation with 0.1 g / L turmeric CDs for 30 minutes under light reduced the spore count by 3.1 log values. Even after extending the treatment time to 60 minutes, 0.1 g / L turmeric CDs still completely killed *Fusarium graminearum* spores. These results indicate that turmeric CDs possess excellent photoelectron conversion properties and exhibit superior antibacterial activity against *Fusarium graminearum* under natural light.

[0069] To further compare the effects of turmeric CDs and curcumin on the survival of Fusarium graminearum spores, turmeric CDs and an equivalent concentration of curcumin were used to treat Fusarium graminearum spores for 30 minutes under both dark and light conditions. The experimental results are as follows: Figure 4 As shown in the figure. Compared with the control group (5.41 Log), under dark conditions, turmeric CDs had no inactivation effect on Fusarium graminearum spores, while treatment with curcumin Cur-0.5 for 30 minutes reduced the Log value by 0.64, which may be related to the toxicity of curcumin itself. However, under light conditions, turmeric CDs-0.05, 0.1, and 0.2 reduced the Log value of Fusarium graminearum spores to 2.97, 2.20, and 2.10, respectively. When the concentration of turmeric CDs increased to 0.3 g / L, it could completely inactivate the Fusarium graminearum spores in the control group. Meanwhile, in the corresponding curcumin treatment groups, after 30 minutes of treatment with curcumin (Cur = 0.05, 0.1, and 0.2), the Log values ​​of *Fusarium graminearum* spores only decreased by 5.29, 5.13, and 3.95, respectively. When the curcumin concentration in the treatment groups increased to 0.3 and 0.5, the Log values ​​of *Fusarium graminearum* spores were only reduced to 3.70 and 3.53, respectively. These results indicate that although curcumin also has an inactivating effect on *Fusarium graminearum* spores, its inactivation effect is far lower than that of turmeric CDs. This may be related to the good photoelectron conversion performance and superior solubility of turmeric CDs. In summary, turmeric CDs can significantly inactivate *Fusarium graminearum* spores under light conditions, thus providing a theoretical basis for the control of Fusarium head blight in the field.

[0070] Example 3: Evaluation of the inhibitory effect of turmeric CDs on Fusarium graminearum mycelial growth.

[0071] Experimental Methods: To evaluate the inhibitory effect of turmeric CDs on the mycelial growth of Fusarium graminearum, spores of different concentrations of turmeric CDs were treated with natural light for 30 min. First, 5 μL of the treated spore suspension was added dropwise to the center of a PDA solid culture dish. The PDA plate was then incubated at 28℃ for 72 h. The diameter of the fungal colony was then measured using the cross-sectional method. The formula for calculating the mycelial growth inhibition rate is: Inhibition rate (%) = (1 - d) / ... t / d c )×100, where d c and d t The colony diameters of the untreated and treated groups are represented respectively. Next, after centrifuging the treated spore suspension at 6000 rpm for 10 min, the spore pellet was transferred back to 10 ml of potato dextrose liquid medium (PDB) and cultured at 28℃ and 180 rpm for 4 h. Then, 10 μL of the spore suspension was taken for observation under a microscope and the spore germination rate was counted.

[0072] Experimental results: such as Figure 5As shown, turmeric CDs treatment for 30 minutes effectively inhibited mycelial growth and conidial germination of Fusarium graminearum spores. Specifically, with increasing turmeric CDs concentration, CDs visibly inhibited mycelial growth, and CDs-0.5, as the maximum treatment dose, completely inhibited normal mycelial growth. Simultaneously, after CDs treatment, the spore germination rate of Fusarium graminearum significantly decreased from 96.33% in the control group to 1.67% in the CDs-0.5 treatment group. Furthermore, CDs-0.1 significantly reduced the spore germination rate to 30.67%, and when the concentration increased to 0.2 g / L, the spore germination rate decreased to below 10%.

[0073] Example 4: Evaluation of the field control effect of turmeric CDs on wheat scab.

[0074] Experimental Methods: To evaluate the field control efficacy of turmeric CDs against wheat scab, a field trial was conducted in Xinxiang, Henan Province. Fusarium spores were collected from CMC medium cultured for 5 days and the concentration was adjusted to 10%. 6 At the wheat flowering stage, 10 μL of spore suspension was inoculated into the floret cavity between the palea and palea of ​​the florets in the middle of the flowering wheat spike. On days 0, 3, 5, and 7 after inoculation, each wheat spike in each treatment group was sprayed with 2 ml of turmeric CDs solution at concentrations of 0, 0.1, 0.3, and 0.5 g / L, respectively. The 0 group was designated as the control group. On day 14 after spore inoculation, disease surveys were conducted, and wheat spikes were randomly sampled and photographed from each plot.

[0075] Experimental results: such as Figure 6 As shown, turmeric CDs treatment effectively controlled the occurrence of wheat scab in the field in a concentration-dependent manner. With increasing turmeric CDs concentration, the number of infected sites on the wheat ears gradually decreased. These results indicate that turmeric CDs have a good control effect on wheat scab in the field, and its control effect is related to the antifungal ability of turmeric CDs against Fusarium graminearum.

[0076] Example 5: Experimental method for evaluating the safety of turmeric CDs on wheat plant growth

[0077] To assess whether turmeric CDs have a negative impact on wheat growth, a safety experiment was conducted on wheat seedlings in a greenhouse. The experiment was divided into four groups. Wheat was cultivated in the greenhouse, and on days 7, 10, and 13 of cultivation, 2 ml of turmeric CDs solution was sprayed onto each wheat plant in each treatment group at concentrations of 0, 0.1, 0.3, and 0.5 g / L, respectively. The 0 concentration was designated as the control group. On day 14 of cultivation, the plant height, fresh weight, dry weight, chlorophyll content, and the levels of superoxide dismutase (SOD) and peroxidase (POD) in the wheat plants were measured. Samples were randomly taken from each treatment group and photographed.

[0078] Experimental results: such as Figure 7 As shown in (A), it can be clearly seen that there was no significant difference in the appearance of the four wheat groups after turmeric CDs treatment. Specifically, as... Figure 7 (B)- Figure 7 As shown in (E), the results regarding plant height, fresh weight, dry weight, and chlorophyll content indicated that turmeric CDs treatment had no significant effect on the plant height, fresh weight, dry weight, and chlorophyll content of wheat seedlings, suggesting that turmeric CDs had no effect on the growth indicators of wheat seedlings. Furthermore, abiotic stress usually stimulates the production of ROS; therefore, the oxidative stress experienced by wheat seedlings can be reflected by measuring the activity of antioxidant enzymes in plants. Figure 7 (F) and Figure 7 As shown in (G), there was no significant difference in SOD and POD activities in wheat seedlings after treatment with turmeric CDs, therefore turmeric CDs do not induce oxidative stress in wheat seedlings. In summary, turmeric CDs have no adverse effects on the growth of wheat seedlings.

[0079] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including modifications made using conventional techniques known in the art that depart from the scope disclosed herein.

Claims

1. Application of turmeric carbon nanodots in any of the following or in the preparation of products having any of the following functions; A1. Prevention and control of plant diseases caused by Fusarium graminearum; A2. Prevention and control of wheat scab; A3. Kills Fusarium spores; A4. Inhibits Fusarium graminearum; A5. Inhibits the growth of Fusarium graminearum spores; A6. Inhibits the germination of Fusarium graminearum spores; The application was performed under natural light conditions. The turmeric carbon nanodots were prepared by a method comprising the following steps: 1) Take turmeric powder, dry it, and set it aside for later use; 2) The system consisting of the turmeric powder and solvent is subjected to a hydrothermal reaction. After the reaction is complete, the mixture is centrifuged and the supernatant is collected. The solvent is anhydrous ethanol or N,N dimethylformamide; The temperature of the hydrothermal reaction is 160°C; The hydrothermal reaction time is 5 hours; 3) The supernatant was purified and dried to obtain the turmeric carbon nanodots.

2. The application according to claim 1, characterized in that: The ratio of the turmeric powder to the solvent is 1g:(4~20)mL.

3. The application according to any one of claims 1-2, characterized in that: The centrifugation speed is 5000~10000 rpm, and the time is 5~10 minutes; The purification was performed using silica gel column chromatography.

4. The application according to any one of claims 1-2, characterized in that: The turmeric carbon nanodots exist in the form of an aqueous solution with a concentration of 0~0.5 g / L but not 0.

5. The use of the bactericidal composition containing turmeric carbon nanodots in any of the following or in the preparation of a product having any of the following functions; A1. Prevention and control of plant diseases caused by Fusarium graminearum; A2. Prevention and control of wheat scab; A3. Kills Fusarium spores; A4. Inhibits Fusarium graminearum; A5. Inhibits the growth of Fusarium graminearum spores; A6. Inhibits the germination of Fusarium graminearum spores; The turmeric carbon nanodots were prepared by a method comprising the following steps: 1) Take turmeric powder, dry it, and set it aside for later use; 2) The system consisting of the turmeric powder and solvent is subjected to a hydrothermal reaction. After the reaction is complete, the mixture is centrifuged and the supernatant is collected. The solvent is anhydrous ethanol or N,N dimethylformamide; The temperature of the hydrothermal reaction is 160°C; The hydrothermal reaction time is 5 hours; 3) The supernatant was purified and dried to obtain the turmeric carbon nanodots.

6. The application according to claim 5, characterized in that: The ratio of the turmeric powder to the solvent is 1g:(4~20)mL.

7. The application according to any one of claims 5-6, characterized in that: The centrifugation speed is 5000~10000 rpm, and the time is 5~10 minutes; The purification was performed using silica gel column chromatography.

8. The application according to any one of claims 5-6, characterized in that: The bactericidal composition further comprises excipients and / or bactericidal components that can be compounded with the turmeric carbon nanodots.

Images