A carbon dot with photocatalytic sterilization and immune induction functions and its preparation method and application

Abstract

The present invention belongs to the field of biological functional materials, and specifically relates to a carbon dot with photocatalytic sterilization and immune induction functions, and a preparation method and application thereof. Aniline compounds and amino acids are dissolved in deionized water, concentrated sulfuric acid is added, and after hydrothermal reaction, green fluorescent carbon dots with a size of less than 5nm can be obtained. The carbon dots will generate a variety of free radicals after being irradiated with ultraviolet light and visible light, and have extremely strong oxidizing properties. The carbon dots of the present invention can be used in the preparation of bactericides and can also be used as plant immune inducers.

Description

Technical Field

[0001] The present invention belongs to the field of biological functional materials, and specifically relates to a carbon dot with photocatalytic sterilization and immune induction functions, and a preparation method and application thereof. Background Art

[0002] Existing fungicides are prone to drug resistance in pathogens. In addition, the preparation methods of existing polypeptide and protein plant immune inducers are complex, costly, and there are few types of chemical immune inducers. There is a lack of immune inducers that are efficient, simple to synthesize, and low in synthesis cost. Carbon dots are a type of zero-dimensional carbon nanomaterials with a size of less than 10nm. Because of their low biotoxicity, good biocompatibility, small size, unique fluorescence properties, etc., carbon dots have attracted widespread attention in plant growth and abiotic stress. At present, there are few photocatalytic carbon dots, and the existing photocatalytic carbon dots are mainly used for photodynamic therapy. For example, Chinese patent CN106390119B discloses a method for synthesizing copper-containing photothermal nanomaterials and their applications. The invention uses o-phenylenediamine and L-cysteine ​​as raw materials, and uses a hydrothermal synthesis method to prepare fluorescent carbon dots with good stability and water solubility in one step, and the carbon dots and copper-containing salt solutions are simply mixed to prepare copper-containing nanomaterials with excellent photothermal properties. The invention ultimately obtains a new type of photothermal nanomaterial with good water dispersibility, low toxicity and excellent photothermal performance for photothermal treatment of tumors. However, there are fewer photosensitivity carbon dots induced by visible light. Summary of the invention

[0003] The present invention mainly provides a carbon dot having both photocatalytic sterilization and immune induction functions:

[0004] A carbon dot with photocatalytic bactericidal and immune induction functions is obtained by hydrothermal reaction of aniline compounds and sulfur-containing amino acids under the action of concentrated sulfuric acid.

[0005] Furthermore, the aniline compound is o-phenylenediamine; and the amino acid is any one of L-cystine and D-cystine.

[0006] Furthermore, the diameter of the carbon dots is 2 to 5 nm.

[0007] Furthermore, the excitation wavelength of the carbon dots is 424 nm.

[0008] The present invention also provides a low-cost preparation method of the above carbon dots, and the technical scheme is as follows:

[0009] A method for preparing the above-mentioned carbon dots with photocatalytic sterilization and immune induction functions comprises the following steps:

[0010] a. Add an aniline compound into deionized water to prepare a 30-95 mmol / L aniline compound solution, dissolve the sulfur-containing amino acid in the aniline compound solution, add concentrated sulfuric acid after dissolution, and stir to mix;

[0011] b. Transfer the mixed solution to a polytetrafluoroethylene reactor for hydrothermal reaction to obtain the product.

[0012] Furthermore, the molar ratio of the sulfur-containing amino acid to the aniline compound is 1:(2-7).

[0013] Furthermore, the molar ratio of the sulfur-containing amino acid to concentrated sulfuric acid is 1:(90-140).

[0014] Furthermore, the temperature of the hydrothermal reaction is 150-180° C., and the time is 3-6 hours.

[0015] The present invention also provides the use of the above-mentioned carbon dots with photocatalytic sterilization and immune induction functions in antibacterial products and / or preparations, wherein the pathogenic microorganisms are microorganisms that can be killed by active oxygen.

[0016] Furthermore, the pathogenic microorganisms are pathogenic fungi and oomycetes.

[0017] The present invention also provides the use of the above-mentioned carbon dots with photocatalytic sterilization and immune induction functions in plant immune induction products and / or preparations, in which the active oxygen generated by the carbon dots under light catalysis induces plants to produce immune stimulation.

[0018] By adopting the above scheme, the method of the present invention has the following advantages:

[0019] 1. The carbon dots with photocatalytic sterilization and immune induction functions of the present invention are synthesized by a one-step hydrothermal method, with a lattice spacing of 0.26 nm, a body color of dark green at high concentrations and light green at low concentrations. The synthesis process is simple and easy to operate, and the synthesis cost is low.

[0020] 2. The present invention uses cystine as a reaction precursor substance and utilizes the disulfide bond of cystine to promote the transfer of electrons and the generation of active oxygen.

[0021] 3. The carbon dots with photocatalytic sterilization and immune induction functions of the present invention can produce 1 O2, O2 ·- and · There are three types of reactive oxygen species, namely, ions, oxygen, and OH, and they can be generated under visible light or ultraviolet light.

[0022] 4. The carbon dots of the present invention can control the amount of active oxygen produced, so that the carbon dots have both bactericidal activity and immune induction ability, and have the functions of preventing and controlling plant diseases.

[0023] 5. The carbon dots of the present invention can effectively kill fungal and bacterial plant pathogens including Phytophthora capsici, Botrytis cinerea and Sclerotinia sclerotiorum, and the carbon dots have an immunostimulatory effect on plants, can induce plants to produce immune responses, and enhance plant disease resistance.

[0024] 6. The carbon dots of the present invention are zero-dimensional and have a size of less than 5 nm, which can shorten the time required for material degradation while improving the biological safety and photocatalytic activity of the material.

[0025] 7. The visible light catalytic and metal-free properties of the carbon dots of the present invention can avoid their own pollution to the environment. They have good biocompatibility, water solubility and degradability, and can be better applied to the prevention and treatment of plant fungal diseases. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 1 is the excitation and emission spectra of the carbon dots obtained in Example 1.

[0027] Figure 2 It is the ultraviolet absorption spectrum of the carbon dots obtained in Example 1 before and after photocatalysis.

[0028] Figure 3 This is a morphology picture of the carbon dots obtained in Example 1 under a high-resolution transmission electron microscope.

[0029] Figure 4 This is the morphology of the carbon dots obtained in Example 1 under an atomic force microscope.

[0030] Figure 5 This is the signal spectrum of the carbon dots obtained in Example 1 generating various active oxygen species under photocatalysis.

[0031] Figure 6 This is a comparison chart of the antibacterial ability test of the carbon dots obtained in Example 1 against Botrytis cinerea, Phytophthora capsici and Sclerotinia sclerotiorum.

[0032] Figure 7 This is a comparison chart of the immune induction test of the carbon dots obtained in Example 1 on tobacco leaves. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Embodiment 1:

[0035] Add 0.3 g of o-phenylenediamine and 0.1 g of L-cystine or D-cystine to 30 mL of ultrapure water, stir evenly, then add 3 mL of 98 wt% concentrated sulfuric acid, stir until the solution becomes clear, transfer to a 100 mL polytetrafluoroethylene reactor, place in an oven, set the oven temperature to 180 ° C, and react for 180 min to obtain a dark green solution.

[0036] Depend on Figure 1 It can be seen that the excitation wavelength of the product is 424 nm. Figure 2 In the figure, the ultraviolet absorption spectrum of the carbon dots before irradiation is mainly distributed in 200-400 nm, the absorption spectrum after photocatalysis is broadened to 200-500 nm, and the absorption spectrum intensity near 450 nm gradually increases, which shows that the carbon dots of the present invention can be catalyzed under visible light or ultraviolet light. Figure 3 and Figure 4 It can be seen that the lattice spacing of carbon dots is 0.26nm, the size distribution is 2 to 5nm, and the height is about 2nm.

[0037] The fluorescent carbon dots obtained in Example 1 were diluted 100 times with ultrapure water, and the paramagnetic spectrum signals of active oxygen were collected under different illumination times. The results are as follows: Figure 5 As shown, carbon dots produced a variety of reactive oxygen species under photocatalysis.

[0038] Embodiment 2:

[0039] 0.3g o-phenylenediamine and 0.1g L-cystine or D-cystine were added to 30mL ultrapure water, stirred evenly, and then 2mL 98wt% concentrated sulfuric acid was added. After stirring until the solution was clear and transparent, it was transferred to a 100mL polytetrafluoroethylene reactor and placed in an oven at 180°C for 180min.

[0040] Example 3

[0041] Add 0.2g o-phenylenediamine and 0.1g L-cystine or D-cystine to 30mL ultrapure water, stir evenly, then add 2mL 98wt% concentrated sulfuric acid, stir until the solution is clear and transparent, transfer to a 100mL polytetrafluoroethylene reactor, place in an oven, set the oven temperature to 150°C, and react for 5h.

[0042] Example 4

[0043] Add 0.2g o-phenylenediamine and 0.1g L-cystine or D-cystine to 30mL ultrapure water, stir evenly, then add 2mL 98wt% concentrated sulfuric acid, stir until the solution is clear and transparent, transfer to a 100mL polytetrafluoroethylene reactor, place in an oven, set the oven temperature to 160°C, and react for 4h.

[0044] Example 5

[0045] Add 0.1 g o-phenylenediamine and 0.1 g L-cystine or D-cystine to 30 mL ultrapure water, stir evenly, then add 3 mL 98 wt% concentrated sulfuric acid, stir until the solution is clear and transparent, transfer to a 100 mL polytetrafluoroethylene reactor, place in an oven, set the oven temperature to 170 ° C, and react for 6 h.

[0046] Example sample test:

[0047] Antibacterial ability test: The bacterial cakes of Phytophthora, Sclerotinia sclerotiorum and Botrytis cinerea grown for 7 days were immersed in the carbon dot solution (3 mg / mL) of Example 1 or deionized water (control group). 4 The samples were irradiated with 100 lux for 45 min, or placed in the dark for 45 min, and then the treated bacterial cakes were inoculated on potato glucose medium. After one week of culture, the Figure 6 As shown in the mycelium growth state diagram, it can be seen that the use of fluorescent carbon dots alone and light alone have no obvious antibacterial effect. Only the simultaneous treatment of carbon dots and light has a significant bactericidal effect on Botrytis cinerea, Phytophthora capsici and Sclerotinia sclerotiorum.

[0048] Plant immune induction ability test: low concentration of carbon dots was used for immune induction treatment. The specific operation method is as follows: 1.5 mg / mL of the carbon dot solution of Example 1 was used to pre-spray tobacco leaves. After 12-24 hours of treatment, the tobacco leaves were infected with Botrytis cinerea hyphae. The infected plants were placed in an incubator at a temperature of 25°C and a humidity of 90% for 5 days to obtain Figure 7 The leaf disease pictures shown in the figure show that the carbon dot treatment reduced the incidence rate and diseased area of ​​tobacco leaves, indicating that carbon dot treatment can enhance the plant's defense ability against pathogens.

[0049] For those skilled in the art, various other corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all of these changes and deformations should fall within the protection scope of the claims of the present invention.

Claims

1. A carbon dot having photocatalytic sterilization and immune induction functions, characterized in that: The method is obtained by subjecting an aniline compound and a sulfur-containing amino acid to a hydrothermal reaction under the action of concentrated sulfuric acid; the aniline compound is o-phenylenediamine; and the amino acid is any one of L-cystine and D-cystine.

2. The carbon dots with photocatalytic sterilization and immune induction functions according to claim 1, characterized in that: The diameter of carbon dots is 2 to 5 nm.

3. The carbon dots with photocatalytic sterilization and immune induction functions according to claim 1, characterized in that: The excitation wavelength of carbon dots is 424 nm.

4. A method for preparing carbon dots with photocatalytic sterilization and immune induction functions according to claim 1, characterized in that: The following steps are involved: a. Add an aniline compound into deionized water to prepare a 30-95 mmol / L aniline compound solution, dissolve the sulfur-containing amino acid in the aniline compound solution, add concentrated sulfuric acid after dissolution, and stir to mix; b. Transfer the mixed solution to a polytetrafluoroethylene reactor for hydrothermal reaction to obtain the product.

5. The method for preparing carbon dots with photocatalytic sterilization and immune induction functions according to claim 4, characterized in that: The molar ratio of the sulfur-containing amino acid to the aniline compound is 1:(2-7); the molar ratio of the sulfur-containing amino acid to concentrated sulfuric acid is 1:(90-140).

6. The method for preparing carbon dots with photocatalytic sterilization and immune induction functions according to claim 4, characterized in that: The temperature of the hydrothermal reaction is 150-180° C. and the time is 3-6 hours.

7. Use of the carbon dots with photocatalytic sterilization and immune induction functions according to any one of claims 1 to 3 in products and / or preparations for inhibiting pathogenic microorganisms, characterized in that: The pathogenic microorganisms are microorganisms that can be killed by active oxygen.

8. The use of carbon dots with photocatalytic sterilization and immune induction functions in products and / or preparations for inhibiting pathogenic microorganisms according to claim 7, characterized in that: The pathogenic microorganism is a pathogenic fungus or an oomycete.

9. Use of the carbon dots with photocatalytic sterilization and immune induction functions according to any one of claims 1 to 3 in plant immune induction products and / or preparations, characterized in that: The reactive oxygen species produced by carbon dots under photocatalysis induces immune stimulation in plants.

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