A thioglycolic acid modified carbon quantum dot and application thereof

Abstract

The application provides a thioglycolic acid modified carbon quantum dot, which is prepared by the following method: (1) preparing a carbon quantum dot solution by using Dicranopteris dichotoma leaves and / or Ricinus communis leaves as raw materials; (2) adding thioglycolic acid into the carbon quantum dot solution obtained in the step (1) so that the concentration of the thioglycolic acid is 0.5mmol-5mmol; after being sufficiently dissolved and mixed, the reaction is carried out at 100-140 DEG C for 1-6 hours to obtain the thioglycolic acid modified carbon quantum dot. The application finds that under suitable conditions, the inhibition effect of the thioglycolic acid modified carbon quantum dot on Ralstonia solanacearum is significantly enhanced, and the minimum inhibitory concentration and the bactericidal concentration are obviously reduced.

Description

Technical Field

[0001] This invention belongs to the field of agricultural disease control technology, specifically relating to a carbon quantum dot modified with thioglycolic acid and its application. Background Technology

[0002] Carbon quantum dots (CDs), also known as carbon dots or carbon nanodots, are a class of zero-dimensional carbon nanomaterials with significant fluorescence properties. They consist of ultrafine, dispersed, quasi-spherical carbon nanoparticles with a size of less than 10 nm. Due to their small diameter, high biocompatibility, and low toxicity, coupled with carbon being one of the most important building blocks of living organisms, they are more easily absorbed and utilized by living organisms. With increasing research on carbon quantum dots, various functionalized carbon quantum dots have been developed; for example, carbon quantum dots exhibit effective antibacterial activity.

[0003] As is well known, the properties exhibited by a substance or class of substances are often endowed by its functional groups (e.g., acids and bases). Carbon dot functionalization modification also primarily achieves a relatively stable state through the interaction between different functional groups, forming covalent, ionic, and metallic bonds, thereby altering the corresponding properties—potentially increasing or decreasing them. Therefore, suitable modifiers may enable carbon dots to achieve unprecedented levels of performance. Summary of the Invention

[0004] Therefore, the purpose of this invention is to provide thioglycolic acid-modified carbon quantum dots and their applications. Thioglycolic acid-modified carbon quantum dots can effectively enhance their inhibitory effect on Ralstonia solanacearum.

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

[0006] A carbon quantum dot modified with thioglycolic acid is prepared by the following method: (1) preparing a carbon quantum dot solution using sedge leaves and / or castor leaves as raw materials; (2) adding thioglycolic acid to the carbon quantum dot solution obtained in step (1) to make the concentration of thioglycolic acid 0.5 mmol to 5 mmol; after fully dissolving and mixing, reacting at 100℃ to 140℃ for 1 h to 6 h to obtain the carbon quantum dot modified with thioglycolic acid.

[0007] In some embodiments, carbon quantum dot solution is prepared by hydrothermal method in step (1).

[0008] Preferably, the hydrothermal method specifically involves: drying the raw material, pulverizing it into a fine powder, adding water, mixing it evenly, placing it at 150℃~250℃ for 8h~14h, centrifuging it, taking the supernatant, filtering it, and obtaining the carbon quantum dot solution.

[0009] In some embodiments, the mass ratio of the fine powder to water is 1:30 to 60.

[0010] In some embodiments, the concentration of thioglycolic acid in step (1) is 1 mmol to 3 mmol.

[0011] In some embodiments, step (2) further includes freeze-drying the reaction product.

[0012] In some embodiments, the reaction time for step (2) is 2-3 hours. Preferably, the reaction time is 2 hours.

[0013] This invention also provides the application of the thioglycolic acid-modified carbon quantum dots described above in the preparation of Ralstonia solanacearum inhibitors or in the preparation of biological agents for the prevention and control of plant diseases caused by Ralstonia solanacearum.

[0014] The present invention also provides the application of the thioglycolic acid modified carbon quantum dots as described above in the prevention and control of plant diseases caused by Ralstonia solanacearum.

[0015] The present invention also provides a Ralstonia solanacearum inhibitor, the inhibitor comprising carbon quantum dots modified with thioglycolic acid as described above.

[0016] In some embodiments, the concentration of the thioglycolic acid-modified carbon quantum dots in the inhibitor is [missing information].

[0017] 5 μg / ml to 50 μg / ml. Preferably, the concentration of the thioglycolic acid-modified carbon quantum dots in the inhibitor is 8 μg / ml to 40 μg / ml.

[0018] The present invention also provides a method for preventing and controlling plant diseases caused by Ralstonia solanacearum, the method comprising: spraying plants or watering plant roots with the inhibitor described above.

[0019] This invention, through research, has found that under suitable conditions, modifying *Rhizoctonia solani* leaf-carbon quantum dots and castor bean leaf-carbon quantum dots with appropriate concentrations of thioglycolic acid significantly enhances the inhibitory effect of thioglycolic acid-modified carbon quantum dots on *Rhizoctonia solani*, while significantly reducing the minimum inhibitory concentration (MIC) and bactericidal concentration (BIC). The thioglycolic acid-modified carbon quantum dots exhibit a significantly increased degree of damage to *Rhizoctonia solani*, even showing instances of breakage and hollowing out, indicating a further enhancement of the toxic effect of thioglycolic acid-modified carbon quantum dots on *Rhizoctonia solani*. This, to some extent, compensates for the limited surface morphological damage of *Rhizoctonia solani* caused by *Rhizoctonia solani* leaf-carbon quantum dots, and further strengthens the destructive effect of castor bean leaf-carbon quantum dots on the surface morphology of *Rhizoctonia solani*. Attached Figure Description

[0020] Figure 1The study aimed to evaluate the antibacterial effects of carbon quantum dots modified with different chemical reagents. The CK group represents the blank control group without carbon dot solution.

[0021] Figure 2 The effect of different concentrations of thioglycolic acid on the antibacterial effect of carbon quantum dot modified compounds was investigated. The CK group represents the blank control group without carbon dot solution.

[0022] Figure 3 The images show the UV and fluorescence absorption spectra of CDs-MQ thiolated and CDs-BM thiolated CDs.

[0023] Figure 4 The results show the antibacterial rates of CDs-MQ and CDs-BM at different concentrations.

[0024] Figure 5 The results show the effects of different concentrations of CDs-MQ and CDs-BM thiolation treatments on the growth curves of Ralstonia solanacearum. The CK group represents the blank control group without carbon dot solution.

[0025] Figure 6 The results of scanning electron microscopy analysis of Ralstonia solanacearum after CDs-MQ and CDs-BM thiolation treatments. Detailed Implementation

[0026] Unless otherwise specified, the experimental methods described in the following embodiments of the present invention are generally performed under conventional conditions. All commonly used chemical reagents used in the embodiments are commercially available products.

[0027] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0028] The terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product, or device that includes a series of steps is not limited to the steps or modules listed, but may optionally include steps not listed, or may optionally include other steps inherent to such process, method, product, or device.

[0029] In this invention, "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0030] In the following examples, the pathogen of bacterial wilt of tomato was *Ralstonia solanacearum*, belonging to the phylum Proteobacteria, class Betaproteobacteria, order Burkholderiales, family Burkholderiaceae, and genus *Ralslonia*. *Ralstonia solanacearum* has been reported to be the pathogen of bacterial wilt in more than 250 plant species, including important crops such as tomato, potato, tobacco, and peanut. All experiments were performed in quadruplicate, and results are expressed as the mean and standard deviation of the four analyses.

[0031] Example 1

[0032] 1. Preparation of carbon quantum dots modified with chemical reagents

[0033] Thioglycolic acid, dicyandiammonium, tetraethylammonium chloride, formamide, thiourea, and polyethyleneimine were selected as chemical reagents to modify carbon quantum dots (CDs-MQ) from scutellaria leaves and carbon quantum dots (CDs-BM) from castor leaves.

[0034] Dried sedge leaves and castor bean leaves were placed in a 60℃ oven and dried. They were then pulverized into fine powder and passed through an 80-mesh sieve. Deionized water was added at a ratio of powder to deionized water of 1:45 (mass ratio), and the mixture was stirred magnetically for 30 min. The mixture was then transferred to a 100 mL reaction vessel and incubated at 180℃ for 11 h. After natural cooling to room temperature, the mixture was centrifuged at 4000 r / min for 10 min. The supernatant was collected and filtered through a 0.22 μm filter membrane to collect CDs-MQ and CDs-BM solutions. 30 mL of CDs-MQ and CDs-BM solutions were then mixed with different amounts of chemical modification reagents in a specific ratio to prepare a 1 mmol mixture. This mixture was reacted at 100℃ for 2 h to prepare chemically modified CDs-MQ and CDs-BM. The mixtures were dialyzed through a 1000 molecular weight dialysis bag for 48 h and stored at 4℃ for later use.

[0035] Take 30 mL of carbon dot modified stock solution, freeze dry at 60 °C to obtain solid powder, weigh it and calculate the concentration of carbon dot modified stock solution.

[0036] The CDs-BM modifier was prepared at a concentration of 12 μg / ml, and the CDs-MQ modifier was prepared at a concentration of 18 μg / ml for antibacterial experiments.

[0037] The antibacterial test method is as follows:

[0038] To assess the antibacterial properties of carbon dots, we compared the effects of different carbon dot modifiers on the biomass of *Ralstonia solanacearum*. The biomass of *Ralstonia solanacearum* was evaluated by measuring the optical density (OD) of the cell suspension at 600 nm. *Ralstonia solanacearum* was grown on nutrient agar liquid medium (0.3% beef extract / 0.5% peptone / 1% glucose). Two ml of overnight-cultured *Ralstonia solanacearum* suspension and two ml of carbon dots at different concentrations were added to test tubes to obtain a 4 ml mixture. The OD 600 of *Ralstonia solanacearum* was 0.1, and the carbon dot concentration was 20 μg / ml. The mixture was incubated at 30℃ with shaking at 200 rpm for 16 h, and the absorbance was recorded at 600 nm. Since the absorbance value of the UV spectrophotometer is relatively accurate in the range of 0-1.0, this experiment, referencing relevant research and conducting preliminary experiments, ultimately set the culture time to 16 hours to ensure a high absorbance that did not exceed 1.0. In addition, we found that carbon dot concentration had a significant impact on absorbance during the experiment. Therefore, each group in this study had a separate blank control to minimize the influence of carbon dot concentration on absorbance. All experiments were performed in quadruplicate, and the results were expressed as the mean ± standard deviation of the four analyses.

[0039] Antibacterial rate = (Control OD value - Carbon point OD value) / Control OD value * 100%;

[0040] Control OD value = Control OD (final value) - Control OD (initial value);

[0041] Carbon point OD value = Carbon point OD (final value) - Carbon point OD (initial value).

[0042] The results are as follows Figure 1 As shown, when thioglycolic acid was selected as the modifier, the carbon quantum dots obtained had a significantly enhanced inhibitory effect on Ralstonia solanacearum.

[0043] 2. Effect of thioglycolic acid concentration on antibacterial effect.

[0044] 30 ml of CDs-MQ solution and CDs-BM solution were mixed with thioglycolic acid in specific ratios to prepare mixtures of 0.5 mmol, 1 mmol, 2 mmol, 3 mmol, 4 mmol, and 5 mmol. These mixtures were reacted at 100 °C for 2 h to prepare thioglycolic acid-modified *Dictamnus dasycarpus* leaf carbon quantum dots and thioglycolic acid-modified castor bean leaf carbon quantum dots. The mixtures were dialyzed through a 1000 molecular weight dialysis bag for 48 h and stored at 4 °C for later use. For the water-based thioglycolic acid group, an equal volume of deionized water was used instead of the carbon dot solution and thioglycolic acid, reacting under the same conditions.

[0045] Take 30 mL of carbon dot modified stock solution, freeze dry at 60 °C to obtain solid powder, weigh and calculate the concentration of carbon dot modified stock solution for antibacterial experiment.

[0046] Using different concentrations of thioglycolic acid as a control: thioglycolic acid was prepared into mixed solutions of 0.5 mmol, 1 mmol, 2 mmol, 3 mmol, 4 mmol and 5 mmol with water. After incubation at 100℃ for 2 h, the solutions were filtered through a 0.22 μm filter membrane, dialyzed through a 1000 molecular weight dialysis bag for 48 h, and freeze-dried at 60℃ to obtain a solid powder. The solid powder was weighed and prepared to a concentration of 15 μg / ml for antibacterial experiments.

[0047] like Figure 2 As shown, mixtures prepared from freeze-dried solid powders of 0.5 mmol, 1 mmol, and 2 mmol of thioglycolic acid aqueous solution significantly promoted the growth of *Ralstonia solanacearum* at a concentration of 15 μg / ml. When the amount of thioglycolic acid added as a modifying agent reached 4 mmol and 5 mmol, the different mixtures at 15 μg / ml showed significant inhibitory effects on *Ralstonia solanacearum*; when the amount of thioglycolic acid added reached 5 mmol, its inhibitory effect was comparable to that of CDs-BM at 12 μg / ml and CDs-MQ at 18 μg / ml. This indicates that thioglycolic acid exhibits a promoting effect at low concentrations and an inhibitory effect at high concentrations on *Ralstonia solanacearum*. However, when the concentration of thioglycolic acid was moderate at 3 mmol, it showed neither significant inhibitory nor significant promoting effects on *Ralstonia solanacearum*.

[0048] Compared to the unmodified form, at a concentration of 18 μg / ml, CDs-MQ showed significantly better inhibitory effects against Ralstonia solanacearum only at 0.5 mmol of thioglycolic acid. The other five thioglycolic acid levels (1 mmol, 2 mmol, 3 mmol, 4 mmol, and 5 mmol) were significantly superior to CDs-MQ, peaking at 3 mmol, approaching 100%. At a concentration of 12 μg / ml, CDs-BM showed significantly better inhibitory effects than CDs-BM at all six thioglycolic acid levels (0.5 mmol, 1 mmol, 2 mmol, 3 mmol, 4 mmol, and 5 mmol), reaching as high as 96% at 3 mmol.

[0049] To ensure a significant improvement in the antibacterial properties of the carbon dot modified compounds, and to eliminate the influence of the modifying reagent, thioglycolic acid, the modification conditions of 100℃ for 2h + 3mmol thioglycolic acid were determined for subsequent research. The prepared carbon dot modified compounds were abbreviated as CDs-MQ thio and CDs-BM thio.

[0050] 3. UV and fluorescence absorption spectra of CDs-MQ thiolated and CDs-BM thiolated CDs

[0051] The ultraviolet absorption spectra of the prepared carbon dots were measured using a spectrophotometer from Shanghai Metash Instruments Co., Ltd. The excitation wavelengths of the prepared carbon quantum dots were measured using a Hitachi F-4600 fluorescence spectrophotometer.

[0052] UV absorption spectrum of carbon dot modified compounds Figure 3 Compared with the unmodified carbon dots, a showed more UV absorption peaks, and the position of the maximum absorption peak appeared significantly earlier, while the intensity was slightly weaker.

[0053] Fluorescence absorption spectrum of carbon dot modified products Figure 3 Compared with the unmodified carbon dots, b to d showed a significant increase in fluorescence intensity, up to 450%, but the positions of the maximum absorption peaks were very close. This may be due to the functional groups attached to thioglycolic acid, which enhanced the fluorescence intensity of the carbon dots.

[0054] Example 2: Determination of Antibacterial Rate

[0055] CDs-MQ thiolated and CDs-BM thiolated were prepared at different concentrations (0 μg / ml, 1 μg / ml, 2 μg / ml, 4 μg / ml, 8 μg / ml, 12 μg / ml, 18 μg / ml, 24 μg / ml, 30 μg / ml) for antibacterial experiments.

[0056] like Figure 4 As shown in Figure a, CDs-BM at thiolated concentrations of 1 μg / ml–4 μg / ml did not show any inhibitory effect on Ralstonia solanacearum, indicating that low concentrations of carbon dots had no significant inhibitory effect on the pathogen. CDs-BM at thiolated concentrations of 8 μg / ml–30 μg / ml showed a significant inhibitory effect on Ralstonia solanacearum, with inhibition rates of 61%, 95%, and 96% at 8 μg / ml, 12 μg / ml, and 18 μg / ml, respectively, compared to 45%, 87%, and 98% for CDs-BM. These inhibition rates were increased by 16% and 8% at concentrations of 8 μg / ml and 12 μg / ml, respectively. When the inhibition rate is 90% and 95%, the actual OD values ​​obtained are only 0.07 and 0.035, respectively, which may be due to some random error. Therefore, when the inhibition rate is ≥95%, it is considered that the concentration of carbon dots at this concentration completely inhibits Ralstonia solanacearum, that is, the thiolated concentration of CDs-BM is ≥12μg / ml, which completely inhibits Ralstonia solanacearum.

[0057] like Figure 4As shown in b, CDs-MQ thiolated concentrations of 1 μg / ml to 4 μg / ml all showed negative inhibition, indicating that low concentrations of CDs-MQ thiolated fungi have a slight promoting effect on the growth of Ralstonia solanacearum. CDs-MQ thiolated concentrations of 8 μg / ml to 30 μg / ml showed significant inhibitory effects on Ralstonia solanacearum, with inhibition rates of 45%, 68%, and 96% at 8 μg / ml, 12 μg / ml, and 18 μg / ml, respectively. Compared to CDs-MQ's 31%, 59%, and 77%, these rates increased by 24%, 9%, and 19%, respectively. Therefore, CDs-MQ thiolated concentrations ≥18 μg / ml showed complete inhibition against Ralstonia solanacearum.

[0058] Compared with unmodified carbon dots, the two carbon dot modifications, CDs-BM thiolated and CDs-MQ thiolated, showed significantly improved inhibitory effects on Ralstonia solanacearum.

[0059] Example 3 Growth Curve Measurement

[0060] Based on the antibacterial rate at different concentrations, four concentrations were set up to further investigate the effect of carbon dot modifiers on the growth cycle of Ralstonia solanacearum at different concentrations.

[0061] Depend on Figure 5 As shown in Figure a, CDs-BM thiocyanate at concentrations of 4 μg / ml and 8 μg / ml had no significant effect on the logarithmic phase of *Ralstonia solanacearum*, consistent with the control group, but the final growth was significantly inhibited. At concentrations of 12 μg / ml and 18 μg / ml, the logarithmic phase of *Ralstonia solanacearum* was not significantly affected, showing a significant difference from the control group, and the final growth remained at an extremely low level. Figure 5 As shown in b, CDs-MQ thiocyanate at concentrations of 8 μg / ml and 12 μg / ml had no significant effect on the logarithmic growth phase of *Ralstonia solanacearum*, consistent with the control group, but the final growth was significantly inhibited. At concentrations of 18 μg / ml and 24 μg / ml, the logarithmic growth phase of *Ralstonia solanacearum* was not significantly affected, showing a large difference from the control group, and the final growth was extremely low. In summary, the inhibitory effect of carbon dot modifiers gradually increased with increasing concentration, significantly affecting all growth stages of *Ralstonia solanacearum*.

[0062] Example 4: Determination of MIC and MBC of Ralstonia solanacearum using carbon dots

[0063] The determination of the minimum inhibitory concentration (MIC) differed slightly from the guidelines of the Clinical and Laboratory Standards Institute (CLSI). Ralstonia solanacearum cultured overnight for 24 hours was centrifuged at 5000 rpm to collect the cells, resuspended in 0.1M PBS buffer, and gradually diluted to prepare a cell suspension with an optical density of 0.1 at 600 nm. Since the inhibition rate had already been determined in Example 2, this experiment selected multiple concentrations near 100% inhibition rate for testing. Specifically, 2 ml of cell suspension was mixed with multiple concentrations of carbon dot culture medium, resulting in a final 4 ml culture system with carbon dot concentrations of 40 μg / ml, 35 μg / ml, 30 μg / ml, 25 μg / ml, 20 μg / ml, 15 μg / ml, 10 μg / ml, and 5 μg / ml. The culture was incubated at 30℃ and 200 rpm for 24 hours, and the OD600 value was measured using a microplate reader. The lowest concentration at which no indicator bacteria growth was observed (considering factors such as random error, i.e., OD 600 growth ≤ 0.05) was taken as the minimum inhibitory concentration (MIC) of carbon dots against Ralstonia solanacearum. Each experiment was repeated 5 times.

[0064] The minimum bactericidal concentration (MBC) was determined by treating bacterial cells with carbon dot concentrations of 70 μg / ml, 65 μg / ml, 60 μg / ml, 55 μg / ml, 50 μg / ml, 45 μg / ml, 40 μg / ml, 35 μg / ml, 30 μg / ml, 25 μg / ml, 20 μg / ml, 15 μg / ml, and 10 μg / ml for 24 h. The cells were then centrifuged and resuspended in 0.1 M PBS buffer to remove drug stress. They were then inoculated into fresh, sterile NA liquid medium and incubated at 30°C and 200 rpm for up to 36 h. The absorbance (OD 600 increase ≤ 0.05) was measured as the minimum bactericidal concentration. Each experiment was repeated five times.

[0065] The MIC and MBC of carbon dots against Ralstonia solanacearum were tested using the above methods. The results of the enzyme-linked immunosorbent assay (ELISA) readings (Table 1) show that the minimum inhibitory concentrations (MICs) of CDs-BM (thiolated) and CDs-MQ (thiolated) were 15 μg / ml and 20 μg / ml, respectively, with minimum bactericidal rates (MBCs) of 35 μg / ml and 45 μg / ml, respectively. Compared to the MIC of CDs (castor bean leaf) at 20 μg / ml and the MBC at 50 μg / ml, the MIC and MBC of CDs-BM (thiolated) decreased by 5 μg / ml and 15 μg / ml, respectively. Compared to the MIC of CDs (Dictamnus dasycarpus leaf) at 25 μg / ml and the MBC at 65 μg / ml, the MIC and MBC of CDs-MQ (thiolated) decreased by 5 μg / ml and 20 μg / ml, respectively.

[0066] Table 1

[0067]

[0068] Example 5: Morphological analysis of Ralstonia solanacearum under scanning electron microscopy

[0069] like Figure 6 a-b, normal Ralstonia solanacearum is a short, stem-like bacterium with a textured surface, single-celled, rounded ends, 0.9-2.0 μm long and 0.5-0.8 μm wide. When Ralstonia solanacearum is treated with 12 μg / ml CDs-BM for 24 h, the cells are small, with obvious surface depressions, significant swelling near both ends in the middle, and severe cell membrane damage. Figure 6 c~d). When Ralstonia solanacearum was treated with CDs-MQ at a concentration of 18 μg / ml for 24 h, the cell membrane of Ralstonia solanacearum was extensively damaged, cell membrane-related functions were paralyzed, some cells split into two halves or were extensively damaged, exposing internal organelles, and even a considerable number of cells had blurred basic morphology and were not easily identifiable. Figure 6 e~f).

[0070] Overall, after modification with chemical reagents, the antibacterial effects of CDs-BM thiolated and CDs-MQ thiolated carbon dots were significantly enhanced, and the damage to the cell membrane and internal structure of Ralstonia solanacearum was more severe. This may be one of the reasons for the improved inhibitory effect on the growth of Ralstonia solanacearum.

[0071] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0072] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. The application of thioglycolic acid-modified carbon quantum dots in the preparation of Ralstonia solanacearum inhibitors or in the preparation of biological agents for the prevention and control of plant diseases caused by Ralstonia solanacearum, wherein the thioglycolic acid-modified carbon quantum dots are prepared by the following method: (1) preparing a carbon quantum dot solution using scutellaria baicalensis leaves and / or castor bean leaves as raw materials; (2) adding thioglycolic acid to the carbon quantum dot solution obtained in step (1) to make the concentration of thioglycolic acid 0.5 mmol to 5 mmol; after fully dissolving and mixing, reacting at 100℃ to 140℃ for 1 h to 6 h, and finally freeze-drying; In step (1), carbon quantum dot solution is prepared by hydrothermal method. The hydrothermal method is as follows: the raw material is dried, crushed into fine powder, water is added, mixed evenly, and placed at 150℃~250℃ for 8h~14h. After centrifugation, the supernatant is taken and filtered to obtain the solution.

2. The application of the thioglycolic acid-modified carbon quantum dots as described in claim 1 in the preparation of Ralstonia solanacearum inhibitors or in the preparation of biological agents for the prevention and control of plant diseases caused by Ralstonia solanacearum, characterized in that, The mass ratio of the fine powder to water is 1:30 to 60.

3. The application of the thioglycolic acid-modified carbon quantum dots as described in claim 1 in the preparation of Ralstonia solanacearum inhibitors or in the preparation of biological agents for the prevention and control of plant diseases caused by Ralstonia solanacearum, characterized in that, The concentration of thioglycolic acid in step (1) is 1 mmol to 3 mmol.

4. The application of thioglycolic acid-modified carbon quantum dots in the prevention and control of plant diseases caused by Ralstonia solanacearum, wherein the thioglycolic acid-modified carbon quantum dots are prepared by the following method: (1) preparing a carbon quantum dot solution using scutellaria baicalensis leaves and / or castor bean leaves as raw materials; (2) adding thioglycolic acid to the carbon quantum dot solution obtained in step (1) to make the concentration of thioglycolic acid 0.5 mmol to 5 mmol; after fully dissolving and mixing, reacting at 100℃ to 140℃ for 1 h to 6 h, and finally freeze-drying; In step (1), carbon quantum dot solution is prepared by hydrothermal method. The hydrothermal method is as follows: the raw material is dried, crushed into fine powder, water is added, mixed evenly, and placed at 150℃~250℃ for 8h~14h. After centrifugation, the supernatant is taken and filtered to obtain the solution.

5. The application of thioglycolic acid-modified carbon quantum dots as described in claim 4 in the prevention and control of plant diseases caused by Ralstonia solanacearum, characterized in that, The mass ratio of the fine powder to water is 1:30 to 60.

6. The application of thioglycolic acid-modified carbon quantum dots as described in claim 4 in the prevention and control of plant diseases caused by Ralstonia solanacearum, characterized in that, The concentration of thioglycolic acid in step (1) is 1 mmol to 3 mmol.

7. A method for preventing and controlling plant diseases caused by Ralstonia solanacearum, characterized in that, The plant roots are sprayed or irrigated with an inhibitor containing carbon quantum dots modified with thioglycolic acid. The carbon quantum dots modified with thioglycolic acid are prepared by the following method: (1) preparing a carbon quantum dot solution using sedge leaves and / or castor leaves as raw materials; (2) adding thioglycolic acid to the carbon quantum dot solution obtained in step (1) to make the concentration of thioglycolic acid 0.5 mmol to 5 mmol; after fully dissolving and mixing, reacting at 100℃ to 140℃ for 1 h to 6 h, and finally freeze-drying. In step (1), carbon quantum dot solution is prepared by hydrothermal method. The hydrothermal method is as follows: the raw material is dried, crushed into fine powder, water is added, mixed evenly, and placed at 150℃~250℃ for 8h~14h. After centrifugation, the supernatant is taken and filtered to obtain the solution.

8. The method for preventing and controlling plant diseases caused by Ralstonia solanacearum as described in claim 7, characterized in that, The mass ratio of the fine powder to water is 1:30 to 60.

9. The method for preventing and controlling plant diseases caused by Ralstonia solanacearum as described in claim 7, characterized in that, The concentration of thioglycolic acid in step (1) is 1 mmol to 3 mmol.

10. The method for preventing and controlling plant diseases caused by Ralstonia solanacearum as described in claim 7, characterized in that, The concentration of the thioglycolic acid-modified carbon quantum dots in the inhibitor is 5 μg / ml to 50 μg / ml.

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