Preparation method and application of bamboo fungus sourced sulfonic group modified carbon quantum dots

Abstract

The invention provides a preparation method and application of bamboo fungus sourced sulfonic group modified carbon quantum dots, and belongs to the technical field of preparation of nano luminescent materials. The carbon quantum dot is prepared by taking bamboo fungus pileus as a carbon source and sodium sulfamate as a modifier through a hydrothermal method. The carbon quantum dot provided by the invention has a very strong inhibition effect on mango colletotrichum gloeosporioides. According to the invention, biological resources are effectively utilized, a foundation is laid for prevention and treatment of phytopathogen, and the application prospect is wide.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of nano-luminescent materials, and particularly relates to bamboo fungus-derived sulfonic acid group-modified carbon quantum dots, a preparation method thereof, and application of the carbon quantum dots in preventing and controlling plant anthracnose. Background Art

[0002] Carbon quantum dots (CQDs), as small carbon-based nanomaterials, have low cytotoxicity, good water solubility and stability, excellent optical properties, a wide range of raw material sources, and are environmentally friendly. They are widely used in various fields, including agricultural pest control, microbial inhibition, bioimaging, sensors, drug delivery, water purification, photoelectric conversion, and medical treatment. In the field of agricultural biocontrol, CQDs can destroy microbial membrane structures through covalent and non-covalent interactions; enter the cytoplasm to assist in the production of large amounts of reactive oxygen species; and release heat energy through the photothermal effect to inhibit microbial activity. Using natural biomass as a precursor can not only improve the utilization of biomass materials, but also obtain carbon quantum dots that have inhibitory effects on microorganisms; for example, carbon quantum dots prepared from banana peels and tea by-products can inhibit Bacillus subtilis; carbon quantum dots synthesized from lactobacillus have inhibitory effects on Ralstonia solanacearum and Xanthomonas campestris; carbon quantum dots synthesized from Impatiens balsamina can inhibit the growth of Penicillium italicum.

[0003] In practical applications, carbon quantum dots can be modified to improve their performance and make them more applicable in the corresponding fields. Carbon quantum dots can be modified in two ways. One is to replace carbon atoms with heteroatoms and dope them into the sp 2 In a hybridized carbon network, the highly regular arrangement of carbon cores is altered. This change to the basic structure of the carbon cores can lead to changes in the fundamental properties of carbon quantum dots, such as altering the interlayer spacing, electron cloud density, energy gap, active sites, and stability. Common doping methods include O, N, S, B, P, halogens, and metal doping. Another approach is to introduce specific functional groups onto the surface of the carbon cores, which can affect the properties of the carbon dots to a certain extent, but more importantly, it imparts functionality to the surface groups of the carbon dots. For example, the introduction of groups with different electronegativity can not only adjust the electron density and electrophilicity of the carbon dots to a certain extent, thereby affecting their performance in electron transfer reactions and introducing new active sites on the surface, but can also enhance the selectivity and stability of the carbon dots in specific chemical reactions. Common surface group modifications include hydroxyl, carboxyl, aldehyde, aromatic, sulfonic, amide, and halogens.

[0004] Anthracnose is a widespread and devastating plant disease caused by the fungus Colletotrichum. It can infect over 3,200 plant species, including fruits, vegetables, crops, and medicinal herbs, throughout their growth process, through stems, leaves, flowers, and seedlings. The pathogen primarily attaches to tender or injured plant parts by producing conidia, forming attachment organs. These invasive spikes then penetrate tissue cells, causing the disease and necrosis. During storage and transportation, approximately 30% to 50% of mangoes rot due to anthracnose, accounting for over 70% of all fruit diseases. Currently, the primary method for controlling mango anthracnose is chemical pesticides. However, widespread use of chemical pesticides can easily lead to the development of pesticide resistance in pathogens, and residual chemical pesticides in the environment pose a threat to human and ecosystem health. Therefore, the development of green antimicrobial agents is crucial for promoting sustainable ecological development. Summary of the Invention

[0005] In order to solve the problem of preventing and controlling plant anthrax diseases and the problem of utilizing waste biomass resources, the present invention provides a method of preparing sulfonic acid-modified carbon quantum dots derived from bamboo fungus by a hydrothermal method using bamboo fungus cap as a precursor.

[0006] To achieve the above objectives, the inventors provide the following technical solutions:

[0007] A method for preparing bamboo fungus-derived sulfonic acid group-modified carbon quantum dots (DE-SS-CQDs) uses the cap of bamboo fungus as a carbon source, sodium aminosulfonate as a modifier, and adopts a hydrothermal method to prepare the carbon quantum dots.

[0008] Furthermore, the preparation method includes the following steps: weighing bamboo fungus cap powder and sodium sulfamate, dispersing them evenly with ultrapure water, placing the sample into a polyfluoroethylene reactor, and hydrothermally reacting at 170-190°C for 6-10 hours; after natural cooling, filtering with filter paper 2-3 times, filtering with a 0.22μm nylon filter head, dialyzing with a 45-1000Da dialysis bag for 18-24 hours, and changing the water every 6-8 hours; and taking the solution in the dialysis bag and freeze-drying it.

[0009] Furthermore, the mass ratio of the bamboo fungus cap powder to sodium sulfamate is (25-35):1.

[0010] Furthermore, the surface of the carbon quantum dots contains hydroxyl, amino, carboxyl, amide, methyl, methylene and sulfonic acid groups.

[0011] Furthermore, the carbon quantum dots are nearly spherical nanoparticles with a diameter of 4.076±1.436 nm, a distinct graphene lattice structure, and a crystallinity of 97-98%.

[0012] Furthermore, the maximum excitation wavelength / emission wavelength of the carbon quantum dots fluorescence are 443 nm / 522 nm respectively.

[0013] Furthermore, the bamboo fungus-derived sulfonic acid group-modified carbon quantum dots are used in the prevention and treatment of plant anthracnose diseases. Specifically, the bamboo fungus-derived functionalized carbon quantum dots are prepared into a 20-40 mg / mL solution and sprayed on plant leaves, flowers, and fruits. This solution can inhibit the fungus Colletotrichum gloeosporioides, thereby preventing and treating anthracnose caused by the bacteria.

[0014] Furthermore, the application of the sulfonic acid group-modified carbon quantum dots derived from bamboo fungus in inhibiting Colletotrichum gloeosporioides in mangoes is to prepare the sulfonic acid group-modified carbon quantum dots derived from bamboo fungus into a 20-40 mg / mL solution and spray it on mango leaves and flowers.

[0015] Furthermore, the bamboo fungus-derived sulfonic acid group-modified carbon quantum dots are used in the preservation of fruits and vegetables.

[0016] Furthermore, the bamboo fungus-derived sulfonic acid group-modified carbon quantum dots are used in the preservation of mangoes. Specifically, the bamboo fungus-derived sulfonic acid group-modified carbon quantum dots are added to a coating base material such as xanthan gum / hydroxypropyl methylcellulose to prepare a coating agent for the preservation of mangoes.

[0017] The beneficial effects of the present invention are:

[0018] (1) The preparation method of the present invention has simple process, low preparation cost, and is green and environmentally friendly.

[0019] (2) Compared with carbon quantum dots prepared using tea processing byproducts, gelatin, etc. as precursors, the carbon quantum dots of the present invention have stronger thermal stability.

[0020] (3) Using the mushroom cap, a by-product of bamboo fungus, as a source to prepare carbon quantum dots not only improves the utilization rate of biological resources, but also obtains renewable biological control materials with good properties, broadens the application scope of bamboo fungus, and lays a theoretical foundation for the application of green biomass-derived carbon quantum dots in the prevention and control of fungal diseases. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The morphology, size and structure of the DE-SS-CQDs described in the specific implementation method, the transmission electron microscope image (100,000 times) of DE-SS-CQDs (a), the particle size distribution (b), the transmission electron microscope image (1,500,000 times) (c) and the X-ray crystal diffraction pattern (d).

[0022] Figure 2Surface functional group characterization of DE-SS-CQDs described in the specific implementation method, Fourier transform infrared spectrum (a), X-ray photoelectron spectrum (b), C spectrum (c), N spectrum (d), O spectrum (e), S spectrum (f), hydrated particle size distribution (g) and Zeta potential distribution (h) of DE-SS-CQDs.

[0023] Figure 3 This is the thermogravimetric change curve of DE-SS-CQDs described in the specific implementation method.

[0024] Figure 4 Optical properties of DE-SS-CQDs described in the specific embodiment.

[0025] Figure 5 Figure 3 shows the antibacterial effect of DE-SS-CQDs on FJAT-32130 as described in the specific implementation method, the inhibition zone test results of DE-SS-CQDs on FJAT-32130 (a), the turbidity degree and mycelial germination status of FJAT-32130 by the doubling dilution method (b), and the growth status of FJAT-32130 by the poisonous plate method (c).

[0026] Figure 6 The preparation process of DE-SS-CQDs and the antibacterial mechanism of DE-SS-CQDs against FJAT-32130 are described in detail. DETAILED DESCRIPTION

[0027] In order to explain the technical content, achieved objectives and effects of the technical solution in detail, the following is a detailed description in conjunction with specific embodiments and accompanying drawings.

[0028] Example 1

[0029] 1 Materials and Methods

[0030] 1.1 Materials and Reagents

[0031] Pathogen strain of mango anthracnose: Colletotrichum gloeosporioides

[0032] FJAT-32130 was stored in glycerol at -80°C and is currently deposited at the Institute of Crop Science, Fujian Academy of Agricultural Sciences. The caps of bamboo fungi were collected in Guangze County, Fujian Province in June 2024, dried at 65°C, crushed, and passed through a 60-mesh sieve. They were then dried and stored at room temperature for later use.

[0033] The sulfonating reagents ethanesulfonic acid (analytical grade), sodium sulfamate (analytical grade), sodium sulfite (analytical grade), and sodium thiosulfate (analytical grade) were purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; hygromycin B (Hyg B, analytical grade) was purchased from Yisheng Biotechnology (Shanghai) Co., Ltd.; PDB medium (5 g / L potato extract powder, 5.0 g / L sodium chloride, 15 g / L glucose, 10 g / L peptone) was purchased from Beijing Aoboxing Biotechnology Co., Ltd.; and agar powder (analytical grade) was purchased from Beijing Biyuntian Biotechnology Co., Ltd. For PDB liquid medium, 35 g of PDB powder was dissolved in 1 L of water; for PDB semi-solid medium, 9 g of agar was added to the PDB liquid medium; and for PDB solid medium, 18 g of agar was added to the PDB liquid medium.

[0034] 1.2 Methods

[0035] 1.2.1 Preparation of carbon quantum dots from bamboo fungus and evaluation of their antibacterial activity

[0036] Using the cap of a bamboo fungus byproduct as a carbon source, 3g of powder and 0.1g of a sulfonated reagent were weighed and evenly dispersed in 30mL of ultrapure water. The sample was placed in a 50mL polyvinyl fluoride reactor and hydrothermally reacted at 180°C for 8 hours. After cooling naturally, the solution was filtered twice with filter paper and a 0.22μm nylon filter tip. The solution was then dialyzed using a 45-1000Da dialysis bag for 24 hours, with the water changed every 8 hours. The resulting powder, obtained by freeze-drying the solution in the dialysis bag, was then dissolved in an appropriate amount of water and set aside.

[0037] The antibacterial activity of carbon quantum dots was evaluated using the poisonous plate method. The growth of FJAT-32130 bacterial cakes on PDA double-layer plates containing 20 mg / mL and 40 mg / mL carbon quantum dots was measured. Sterile water was added as a blank control. When the bacterial cakes filled the plates, the growth diameter and inhibition rate were calculated.

[0038] 1.2.2 Structural Characterization of DE-SS-CQDs

[0039] The morphology and nanometer diameter of carbon quantum dots were characterized using a transmission electron microscope (TEM) at an operating voltage of 200 kV. The lattice structure of carbon quantum dots was characterized using an X-ray diffraction analyzer (XRD); the test range was 5° to 90°, the scanning rate was 2° / min, Cu-Kα rays were used as the light source, the voltage was 40 kV, and the current was 50 mA. The infrared absorption of carbon quantum dots was measured on an infrared spectrometer (FT-IR) using the pellet method to analyze the surface groups of carbon quantum dots; the test wavenumber range was 500 to 4000 cm -1 , with a resolution of 4cm -1 , the sampling interval is 0.5cm -1, the number of scans was 32. X-ray photoelectron spectroscopy (XPS) was used to analyze the elemental composition of carbon quantum dots, and the functional groups corresponding to the infrared absorption peaks were verified again by measuring the fine spectra of the main elements; the test pressure was 2.0×10 -7 mbar, a spot size of 400 μm, an operating voltage of 12 kV, and a filament current of 6 mA. The full spectrum scan energy was 100 eV with a step size of 1 eV; the fine spectrum scan energy was 50 eV with a step size of 0.1 eV. The hydrated particle size and zeta potential of the carbon quantum dots were analyzed using a nanoparticle size analyzer (DLS). The thermal stability of the carbon quantum dots was analyzed using a thermogravimetric analyzer (TG) in a nitrogen-filled atmosphere. The test temperature range was 30–800°C, the heating rate was 10°C / min, and the data acquisition interval was 0.4 s.

[0040] 1.2.3DE-SS-CQDs Fluorescence Performance Testing

[0041] The ultraviolet absorption of the carbon quantum dots was measured using a full-wavelength microplate reader over a wavelength range of 200–700 nm with a 1 nm step size. The fluorescence of the carbon quantum dots under 365 nm ultraviolet light was observed using a darkroom UV analyzer. The fluorescence excitation and emission wavelengths of the carbon quantum dots, as well as their wavelength dependence, were analyzed using a fluorometer (FL) with a 1 nm step size and a 2 nm slit size.

[0042] 1.2.4 Antibacterial activity of DE-SS-CQDs against FJAT-32130

[0043] FJAT-32130 was activated multiple times on PDB solid medium until the colonies were uniform in morphology. A single colony was selected and cultured in a shaker at 30°C and 170 rpm for 5 days. Spores were obtained by filtering the mycelium through double-layer lens paper.

[0044] The agar diffusion method was used to test the diameter of the inhibition zone of DE-SS-CQDs against FJAT-32130. The double-layer plate contained 5×10 6 Sterile water was used as the negative control (CK), Hyg B (500 μg / mL) was used as the positive control, the DE-SS-CQDs concentration was 300 mg / mL, and the inhibition zone size was measured after incubation at 30°C for 3-4 days.

[0045] The minimum inhibitory concentration (MIC) of DE-SS-CQDs against FJAT-32130 was measured by serial dilution method. PDB supplemented with sterile water was used as negative control. The concentration gradient of carbon quantum dots was 100, 50, 25, 12.5, 6.25, 1.13, 1.56 and 0.78 mg / mL. The volume of PDB in 96-well plates was 100 μL. The spore concentration was 1×10 5CFU / mL, and observe the turbidity of the bacterial solution after culturing at 30℃ for 2 days, and observe the spore germination status under a microscope.

[0046] The inhibitory effect of DE-SS-CQDs on FJAT-32130 was tested using a toxic plate assay. A concentration gradient of 0, 20, and 40 mg / mL of carbon quantum dots was used. Fresh bacterial cakes with a diameter of 8 mm were inoculated on the plates, and the diameters of the cakes were measured every two days until the mycelium in the blank control filled the entire plate.

[0047] 2 Results and Analysis

[0048] 2.1 Antibacterial results of carbon quantum dots modified with different sulfonation reagents

[0049] The inhibition results of bamboo fungus carbon quantum dots modified with different sulfonation reagents on FJAT-32130 are shown in Table 1: All modified bamboo fungus carbon quantum dots showed significant inhibitory effects on FJAT-32130. Compared with unmodified bamboo fungus carbon quantum dots, the carbon quantum dots modified with sodium sulfamate (SS) showed significantly improved inhibition against FJAT-32130 and showed the best effect. Therefore, sodium sulfamate was used as the sulfonation reagent in the subsequent preparation, and the bamboo fungus-derived sulfonic acid group-modified carbon quantum dots prepared were designated DE-SS-CQDs.

[0050] Table 1 Diameter and inhibition rate of FJAT-32130 on carbon quantum dot plates modified with different sulfonated reagents

[0051]

[0052] Note: Different letters in the table indicate significant differences at the 0.05 level detected by Duncan method.

[0053] 2.2 Morphology and structure of carbon quantum dots

[0054] The TEM results of DE-SS-CQDs are as follows Figure 1 As shown in a, carbon quantum dots are evenly dispersed in aqueous solution, and their diameter distribution range is 4.076±1.436nm ( Figure 1 b). DE-SS-CQDs have obvious lattice structure ( Figure 1 c), the lattice interlayer spacing is about 0.21nm, which is attributed to the graphite (100) crystal plane in the carbon core. The 2θ diffraction angle calculated according to the Bragg equation nλ = 2dsinθ should be 21.5°, which is close to the diffraction peak 2θ = 21.67° in the XRD pattern of DE-SS-CQDs ( Figure 1 d), the crystallinity was calculated by Jade-6 software to be 97.84%.

[0055] 2.3DE-SS-CQDs surface functional group analysis

[0056] The FT-IR analysis results of DE-SS-CQDs are shown in Figure 2. Figure 2 As shown in a. At 3391cm -1 The absorption peak at 1652 cm is caused by the stretching vibration of OH in the hydroxyl group or NH in the amino group on the surface of the carbon quantum dots, indicating the presence of hydroxyl and amino groups; -1 The absorption peak at 1400 cm is caused by C=O in the carboxyl group or amide group, indicating the presence of carboxyl and amide groups. -1 The absorption peak at 2931cm caused by the CN stretching vibration in the amide group further supports the existence of the amide group; -1 and 1452cm -1 The absorption peaks at 1050 cm and 1060 cm are caused by the stretching vibration and bending vibration of CH in methyl and methylene groups respectively; -1 and 608cm -1 The absorption peaks at are caused by the stretching vibration and bending vibration of the SO bond in the sulfonic acid group, which are characteristic absorption peaks of the sulfonic acid group. Combined with the above analysis, the DE-SS-CQDs surface contains hydroxyl, amino, carboxyl, amide, methyl, methylene and sulfonic acid groups.

[0057] XPS was used to further analyze the surface elemental composition and chemical state of DE-SS-CQDs. Figure 2 b) shows the four main binding energies of DE-SS-CQDs at 285.99eV, 400.16eV, 532.58eV and 168.78eV, which are assigned to the 1s orbital of C, N, O and the 2p orbital of S, indicating that DE-SS-CQDs are mainly composed of these four elements, accounting for 59.80%, 6.36%, 31.54% and 0.62% respectively. C1s spectrum ( Figure 2 c) The three peaks at 284.82eV, 286.25eV and 288.08eV belong to CC / CH, CO / CN and C=O, accounting for 34.86%, 50.83% and 14.31% respectively; N1 spectrum ( Figure 2 d) The two characteristic peaks at 399.90eV and 401.79eV correspond to CN and NR4 (RC / RH), accounting for 88.96% and 11.04% respectively; O1s spectrum ( Figure 2 e) The two peaks at 531.25eV and 532.59eV are C=O / SO and CO, accounting for 19.87% and 80.22% respectively; S2p spectrum ( Figure 2f) In (f), 163.58 eV and 168.19 eV correspond to C-S and S-O respectively, accounting for 23.90% and 76.10% respectively. The results of XPS for the analysis of surface groups are consistent with those of Fourier transform infrared spectroscopy.

[0058] Polar groups such as hydroxyl, amino, carboxyl, amide, and sulfonic acid groups on the surface of DE-SS-CQDs are prone to adsorbing water molecules, making it easy to form a thick hydration layer in water, and the range of its hydrated particle size ultimately reaches 406.1 ± 100.5 nm ( Figure 2 g); Generally, sulfonic acid groups and carboxyl groups carry negative charges, groups such as hydroxyl and amide groups are neutral, and amino groups only carry positive charges under acidic conditions. Therefore, ultimately, the overall potential of DE-SS-CQDs is determined to be negatively charged, and its Zeta potential distribution is -25.42 ± 15.01 mV ( Figure 2 h).

[0059] 2.4 Thermal stability of DE-SS-CQDs

[0060] The thermogravimetric change curve of DE-SS-CQDs is as Figure 3 shown, and it can be seen that the decomposition of DE-SS-CQDs can be roughly divided into six stages. When t < 110 °C, the weight loss of DE-SS-CQDs is about 4.93%, and the loss at this stage is caused by the evaporation of the water molecules adsorbed by DE-SS-CQDs due to heat. When 110 < t < 185 °C, the weight loss is about 3.06%, which is due to the decomposition of unstable surface groups such as hydroxyl and amino groups. In the stage of 185 < t < 275 °C, the weight loss is about 15.33%, corresponding to the decomposition of methyl and methylene groups on the surface of DE-SS-CQDs. In the stage of 275 < t < 370 °C, the weight loss is about 27.10%, because the carboxyl and amide groups on the surface of DE-SS-CQDs undergo pyrolysis at this temperature. In the stage of 370 < t < 530 °C, the weight loss is about 16.85%, and the sulfonic acid groups with higher thermal stability are decomposed in this stage. When t > 530 °C, the decomposition of the groups in the carbon core approaches completion, and the amorphous carbon begins to decompose and rearrange, transforming into graphite microcrystals, and the proportion of sp 2 carbon increases, and the degree of graphitization improves. Finally, the mass proportion of the carbon core of DE-SS-CQDs is 28.23%. For carbon quantum dots prepared with by-products of tea processing as precursors at 800 °C, the decomposition of their surface groups ends completely in the stage of 150 - 300 °C, and the carbon core begins to decompose at 400 °C; for g-CDs prepared from gelatin by hydrothermal method, the amorphous carbon part begins to decompose at 230 °C, and the surface groups decompose at 400 °C; compared with these biomass-derived carbon quantum dots, DE-SS-CQDs have stronger thermal stability.

[0061] Optical properties of 2.5DE-SS-CQDs

[0062] The UV-visible spectrum of DE-SS-CQDs is shown in Figure 2. Figure 4 As shown in a, there are two obvious absorption peaks at 217nm and 280nm. The absorption peak at 217nm is mainly due to the n-π * The absorption peak at 280nm is from π→π in the carbon core. * The transition is dominant, reflecting its graphene-like structure. 2 The π electrons in the carbon cluster are transformed into excited π * When sp 2 The radiative transition of electron-hole pairs in carbon clusters can generate fluorescence. Therefore, under short excitation wavelength (365nm) ultraviolet irradiation, DE-SS-CQDs emit blue fluorescence ( Figure 4 b), whose maximum excitation wavelength / emission wavelength are 443nm / 522nm respectively ( Figure 4 c), whose emission has a clear wavelength dependence ( Figure 4 d), as the excitation wavelength increases from 396 nm to 476 nm, its maximum emission wavelength also red-shifts from 491 nm to 545 nm, and the emission peak intensity first increases and then decreases.

[0063] Antibacterial activity of 2.6DE-SS-CQDs against FJAT-32130

[0064] The inhibition effect of DE-SS-CQDs on FJAT-32130 is as follows Figure 5 As shown in a, the corresponding inhibition zone diameter is shown in Table 2. It can be seen that SS itself has no inhibitory effect on FJAT-32130, but DE-SS-CQDs has a significant inhibitory effect on FJAT-32130, and its inhibition zone size is 10.24±2.40mm.

[0065] MIC test results ( Figure 5 b) showed that after 48 h of culture, when the concentration of DE-SS-CQDs was less than 12.5 mg / mL, the bacterial solution was turbid. When the concentration was 12.5 mg / mL, the bacterial solution was slightly turbid, and a small amount of bacterial solution was aspirated and mycelial growth was observed under a 400x microscope; when the concentration of DE-SS-CQDs was greater than 12.5 mg / mL, the bacterial solution was clear and the spores did not germinate into mycelia, indicating that the MIC of DE-SS-CQDs against FJAT-32130 was 25 mg / mL.

[0066] The antibacterial rate of DE-SS-CQDs on FJAT-32130 was measured using the poisonous plate method. The growth state of FJAT-32130 in the PDA plate of carbon quantum dots is as follows: Figure 5 c, and colony diameters are shown in Table 3. As the concentration of DE-SS-CQDs in the plate increased, the inhibitory effect on FJAT-32130 became more pronounced. Based on the control's bacterial cake filling the medium on day 8, the inhibition rate of DE-SS-CQDs against FJAT-32130 was 20.47 ± 4.48% at a concentration of 20 mg / mL, and 37.90 ± 7.84% at a concentration of 40 mg / mL.

[0067] Table 2 Diameter of inhibition zone of DE-SS-CQDs against FJAT-32130

[0068]

[0069] Note: Different letters in the table indicate significant differences at the 0.05 level detected by Duncan method.

[0070] Table 3 Colony diameters of FJAT-32130 on different plates

[0071]

[0072]

[0073] The potential antibacterial mechanism of DE-SS-CQDs against Colletotrichum gloeosporioides is as follows Figure 6 As shown in the following data: (1) The nanometer diameter of DE-SS-CQDs is only 4nm, which can enhance its ability to enter the fungal cell through its own small size effect, promote interaction with fungal intracellular proteins, nucleic acids, etc., and affect their normal function. This is consistent with the results that carbon quantum dots (diameter 2.0±0.3nm) prepared with chlorhexidine gluconate can easily enter the bacterial cell and interact with its proteins and nucleic acids. (2) DE-SS-CQDs have a clear lattice structure, and the sp 2 The hybridized carbon atoms form conjugated π bonds, which can efficiently transfer electrons. Under light excitation, electrons jump to form electron-holes, which reduce oxygen, hydrogen peroxide, etc. to superoxide radicals, assisting the production of reactive oxygen species, which can damage cell membranes and proteins. (3) The surface of DE-SS-CQDs carries a negative charge, which makes it easier to interact with divalent cations such as Ca on the cell wall that maintain membrane integrity. 2+ Mg 2+ Equivalent chelation destroys the integrity of the cell wall; DE-SS-CQDs can combine with the negatively charged surface of bacteria through the surface protonated amide functional groups, approach and bind to the cell membrane, protein and even nucleic acid through non-covalent and covalent interactions, and destroy their structure and function.

[0074] In summary, the present invention uses the by-product of the bamboo fungus cap as a carbon source and adopts a hydrothermal method with simple preparation process, low cost and green environmental protection to synthesize carbon quantum dots DE-SS-CQDs, which have good fluorescence properties and emit blue fluorescence under short-wavelength ultraviolet light. DE-SS-CQDs have a spherical structure and are rich in functional groups such as hydroxyl, amino, carboxyl, amide, methyl, methylene and sulfonic acid groups on the surface. The minimum inhibitory concentration MIC of DE-SS-CQDs against Colletotrichum gloeosporioides FJAT-32130 is 25 mg / mL; when the concentration of DE-SS-CQDs is 1 / 2MIC (12.5 mg / mL), it can significantly inhibit the growth and reproduction of FJAT-32130.

[0075] It should be noted that although the above embodiments have been described herein, this does not limit the scope of patent protection of the present invention. Therefore, based on the innovative concept of the present invention, changes and modifications to the embodiments described herein, or equivalent structural or equivalent process transformations made using the contents of the present invention's specification and drawings, and direct or indirect application of the above technical solutions to other related technical fields, are all included in the scope of patent protection of the present invention.

Claims

1. A method for preparing sulfonic acid group-modified carbon quantum dots derived from bamboo fungus, characterized in that: The preparation method uses the cap of bamboo fungus as a carbon source, sodium aminosulfate as a modifier, and adopts a hydrothermal method to prepare carbon quantum dots.

2. The method for preparing sulfonic acid group-modified carbon quantum dots derived from bamboo fungus according to claim 1, wherein: The method comprises the following steps: weighing bamboo fungus cap powder and sodium sulfamate, evenly dispersing them with ultrapure water, placing the samples into a polyfluoroethylene reactor, and subjecting them to a hydrothermal reaction at 170-190° C. for 6-10 hours; after natural cooling, filtering with filter paper 2-3 times, filtering with a 0.22 μm nylon filter head, dialyzing with a 45-1000 Da dialysis bag for 18-24 hours, and changing the water every 6-8 hours; and taking the solution in the dialysis bag and freeze-drying it.

3. The method for preparing sulfonic acid group-modified carbon quantum dots derived from bamboo fungus according to claim 1 or 2, characterized in that: The mass ratio of the bamboo fungus cap powder to sodium sulfamate is (25-35):

1.

4. The method for preparing sulfonic acid group-modified carbon quantum dots derived from bamboo fungus according to any one of claims 1 to 3, characterized in that: The surface of the carbon quantum dots contains hydroxyl, amino, carboxyl, amide, methyl, methylene and sulfonic acid groups.

5. The method for preparing sulfonic acid group-modified carbon quantum dots derived from bamboo fungus according to any one of claims 1 to 3, characterized in that: The carbon quantum dots are nearly spherical nanoparticles with a diameter of 4.076±1.436 nm, a distinct graphene lattice structure, and a crystallinity of 97-98%.

6. The method for preparing sulfonic acid group-modified carbon quantum dots derived from bamboo fungus according to any one of claims 1 to 3, characterized in that: The maximum excitation wavelength / emission wavelength of the carbon quantum dot fluorescence are 443nm / 522nm respectively.

7. Use of the sulfonic acid group-modified carbon quantum dots derived from bamboo fungus according to any one of claims 1 to 6 in preventing and controlling plant anthracnose diseases.

8. Use of the sulfonic acid group-modified carbon quantum dots derived from Dictyophora spp. as claimed in any one of claims 1 to 6 in inhibiting Colletotrichum gloeosporioides.

9. Use of the bamboo fungus-derived sulfonic acid group-modified carbon quantum dots according to any one of claims 1 to 6 in preserving fruits and vegetables.

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