Plant polyphenol carbon dots with siderophore function as well as preparation method and application of plant polyphenol carbon dots
Plant polyphenol carbon dots prepared by hydrothermal synthesis solve the problem of low iron utilization in calcareous or alkaline soils, achieve efficient chelation of trivalent iron ions, promote plant absorption of iron, and improve crop yield and quality. They are green, environmentally friendly and low-cost.
Patent Information
- Application Number
- CN202511077120.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-01
- Publication Date
- 2025-10-17
AI Technical Summary
In the existing technology, the bioavailability of iron in calcareous or alkaline soils is low, leading to iron deficiency chlorosis in crops. Existing iron carriers are costly and inefficient, making it difficult to effectively improve crop yield and quality.
Plant polyphenols were used as carbon sources and plant polyphenol carbon dots with iron carrier function were prepared by hydrothermal synthesis. The particles are small and carry negative charge. Sodium sulfite was used as a reducing agent and surface modifier. The preparation process is green and environmentally friendly. The particle size is 2.86nm, the surface negative charge is -29.8mV, and it can efficiently chelate trivalent iron ions.
The prepared plant polyphenol carbon dots improve the bioavailability of iron in alkaline or calcareous soils and promote the absorption of iron by plants. They have the advantages of being green, low-cost, and easy to scale up, and can promote plant growth and increase crop yields under iron-deficient conditions.
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of carbon dot preparation, and particularly relates to a plant polyphenol carbon dot with an iron carrier function and a preparation method and application thereof. BACKGROUND
[0002] Carbon dots are a kind of zero-dimensional carbon nanomaterials with a particle size of less than 10 nm, which are composed of amorphous and crystalline carbon cores and contain different oxygen-containing functional groups such as hydroxyl and carboxyl on the surface of the carbon cores, and mainly composed of carbon, hydrogen and oxygen, and the content of carbon is relatively high. Carbon dots have become one of the research hotspots of many scholars due to their excellent optical properties, good water solubility, low toxicity and biocompatibility and many other excellent properties. Since carbon dots were discovered, various methods for synthesizing carbon dots have been developed, which can be roughly divided into two categories: "top-down" synthesis method and "bottom-up" synthesis method, including arc discharge method, electrochemical synthesis method, chemical oxidation method, combustion method, hydrothermal synthesis method, microwave synthesis method and template method. The hydrothermal synthesis method can synthesize carbon dots from a variety of precursors, and this method is simple, safe and efficient, and friendly to the environment. As a new type of zero-dimensional carbon nanomaterial, carbon dots have many excellent properties, and are widely studied in various fields. At present, carbon dots have good application prospects in the fields of biological imaging, sensors, phototherapy technology, drug carriers, environmental monitoring, chemical analysis and agriculture.
[0003] Plant polyphenols are a class of secondary metabolites with polyphenol structure widely existing in plant bodies, mainly existing in the skin, roots, leaves and fruits of plants. In recent years, the research on polyphenols involves food, medicine, chemical industry and other fields, including the chemical reaction characteristics of polyphenols with proteins, polypeptides, amino acids and metal ions and the ability of polyphenols to scavenge free radicals, which can realize the application of polyphenols in medicine, food, daily chemicals, environmental protection and other fields. However, polyphenols themselves have the characteristics of low water solubility and poor stability, which also limits the research and utilization of polyphenols.
[0004] Agriculture is the most important basic industry in the national economy. However, iron is one of the most important limiting factors of agricultural productivity, which plays an important role in photosynthesis, respiration and various metabolic processes of crops. Therefore, sufficient iron is essential for the growth and development of crops. However, nearly one-third of the soil in the world is iron-deficient, especially in calcareous or alkaline soil, iron mainly exists in the form of insoluble hydroxide, which reduces the bioavailability of iron in soil, so crops are difficult to absorb and utilize iron, and even cause iron-deficiency chlorosis, resulting in crop yield reduction and economic loss. Siderophores are compounds secreted by microorganisms and plants that can efficiently chelate ferric ions and facilitate iron element uptake. In the soil environment, siderophores can effectively mediate the competition and utilization of iron resources. However, the current natural siderophores are expensive, and their application to improve crop yield and quality in calcareous soil is costly and low in efficiency.
[0005] Therefore, there is an urgent need to provide a preparation and application of plant polyphenol carbon dots with siderophore function. SUMMARY
[0006] In view of the above technical problems, the present application provides a plant polyphenol carbon dot with siderophore function, a preparation method and application thereof. The plant polyphenol carbon dot prepared by the preparation method of the present application has the advantages of small particle size, carrying negative charge, low toxicity, good biocompatibility, low cost, high yield and simple process, and has good application prospect in efficient chelation of ferric ions and facilitation of iron element uptake.
[0007] To achieve the above-mentioned purpose, the present application provides the following technical solutions:
[0008] One of the technical solutions of the present application is:
[0009] A preparation method of a plant polyphenol carbon dot with siderophore function, comprising the following steps:
[0010] Dissolving plant polyphenol and sodium sulfite in water to obtain a mixed solution;
[0011] The mixed solution is subjected to hydrothermal reaction, cooling, centrifugation, filtration, dialysis and freeze-drying in sequence to obtain the plant polyphenol carbon dot.
[0012] Beneficial effects: firstly, the plant polyphenol and sodium sulfite are dissolved in water to form a mixed solution according to a certain mass ratio. The plant polyphenol is a natural polyphenolic compound with abundant phenolic hydroxyl and carboxyl functional groups, which is an ideal carbon source and functional precursor. Sodium sulfite acts as a reducing agent and surface modifier, which helps to control the formation of carbon nuclei and the introduction of surface functional groups during the reaction. The synergistic effect of the two provides a good chemical basis for the formation of carbon dots. In addition, the selection of plant polyphenol as a carbon source not only realizes the reuse of biological waste, but also makes the entire synthesis process green, environmentally friendly and non-toxic side effects; the hydrothermal synthesis method is a mild, efficient and environmentally friendly preparation method. After the reaction is completed, cooling, centrifugation and filtration are carried out to remove unreacted raw materials, by-products and large particle impurities, so as to obtain a pure carbon dot solution. This step helps to improve the uniformity and purity of the product, and provides quality assurance for subsequent application; dialysis can effectively remove small molecular impurities and inorganic salts in the solution that do not participate in the reaction, and further purify the carbon dot product. Long-term dialysis ensures the high purity and good biocompatibility of the final product, laying a foundation for its application in the fields of agriculture and biology; freeze-drying treatment is not only conducive to the long-term preservation and transportation of the product, but also facilitates the quantitative use in subsequent applications. Low-temperature operation during freeze-drying avoids the destruction of the structure and function of the carbon dots, ensuring the stability of their performance.
[0013] In summary, the synergistic effect of each step in the preparation method disclosed in the present application fully utilizes the advantages of plant polyphenol as a carbon source, and successfully prepares plant polyphenol carbon dots with excellent performance by combining the efficiency and controllability of the hydrothermal synthesis method. The average particle size of the obtained carbon dots can reach 2.86nm, the surface carries negative charges (ζ=-29.8mV), has good water solubility, biocompatibility, low toxicity and high efficient chelation of trivalent iron. These characteristics make it have broad application prospects in improving the bioavailability of iron in alkaline or calcareous soil, promoting plant absorption of iron elements, and have the advantages of green, low cost and easy scale production.
[0014] Optionally, the mass ratio of the plant polyphenol to sodium sulfite is 1:(0.1-5).
[0015] Optionally, the total concentration of plant polyphenol and sodium sulfite in the mixed solution is 10mg / mL.
[0016] Optionally, the temperature of the hydrothermal reaction is 160-200℃, and the time of the hydrothermal reaction is 6-12h.
[0017] Beneficial effects: In the present application, the carbonization and crosslinking of plant polyphenol molecules are effectively promoted at 160-200 DEG C for 6-12 hours, forming carbon dots with nanostructure and introducing a large number of oxygen-containing functional groups on the surface. This process not only improves the water solubility and stability of carbon dots, but also provides abundant active sites for subsequent chelation of metal ions (such as Fe 3+ ) and other metal ions. In addition, the hydrothermal method is simple in operation, good in repeatability, and suitable for large-scale production.
[0018] Optionally, the molecular weight cut-off of the dialysis bag used in the dialysis process is 200 Da, and the dialysis time is 72-96 h.
[0019] Beneficial effects: In the present application, the dialysis process using a dialysis bag with a molecular weight cut-off of 200 Da for 72-96 h can effectively remove small molecular impurities and inorganic salts in the solution that do not participate in the reaction, further purifying the carbon dot product. Long-term dialysis ensures the high purity and good biocompatibility of the final product, laying a foundation for its application in the fields of agriculture and biology.
[0020] Optionally, the conditions in the freeze-drying process are as follows:
[0021] Freeze-drying at a temperature of-50 to-60 DEG C for 48-72 h.
[0022] Beneficial effects: In the present application, the carbon dot solution is converted into a solid powder by freeze-drying at-50 to-60 DEG C for 48-72 h. Freeze-drying treatment is not only conducive to long-term preservation and transportation of the product, but also facilitates quantitative use in subsequent applications. Low-temperature operation during freeze-drying avoids the destruction of the structure and function of carbon dots, ensuring the stability of their performance.
[0023] Technical solution two of the present application:
[0024] A plant polyphenol carbon dot with siderophore function is prepared by the above preparation method.
[0025] Optionally, the average particle size of the plant polyphenol carbon dot with siderophore function is 2.86 nm.
[0026] Optionally, the negative charge of the plant polyphenol carbon dot with siderophore function is-29.8 mV.
[0027] Technical solution three of the present application:
[0028] The above-mentioned plant polyphenol carbon dot with siderophore function is used for promoting plant growth, characterized in that the plant polyphenol carbon dot with siderophore function is chelated with trivalent iron to promote the growth of plants under iron deficiency conditions.
[0029] Compared with the prior art, the present application has the following advantages and technical effects:
[0030] (1) The present application uses plant polyphenols (bark extract) as a carbon source, reuses biological waste, and greenly synthesizes plant polyphenol carbon dots, thereby reducing production costs, being green and pollution-free, and having no toxic side effects.
[0031] (2) The present application uses a hydrothermal synthesis method to prepare plant polyphenol carbon dots, which has the advantages of simple operation, high efficiency, and can be produced on a large scale, and the prepared plant polyphenol carbon dots have good water solubility.
[0032] (3) The particle size and charge of the carbon dots will affect the absorption of plants, and carbon dots with small particle size and negative charge are more easily absorbed and transported into the plant body. The plant polyphenol carbon dots prepared by the present application have an average particle size of 2.86 nm and carry negative charges (ζ = -29.8 mV). Therefore, the plant polyphenol carbon dots prepared by the present application have the advantage of entering the plant body.
[0033] (4) The plant polyphenol carbon dots prepared by the present application can efficiently chelate trivalent iron ions and have the ability to reduce trivalent iron to divalent iron, and can dissolve trivalent iron from alkaline or lime soils. BRIEF DESCRIPTION OF DRAWINGS
[0034] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute improper limitations on the present application. In the drawings:
[0035] Figure 1 The TEM characterization diagram of the plant polyphenol carbon dots prepared for Example 1 of the present application, and the HRTEM diagram and particle size distribution diagram are shown in the inserted figures;
[0036] Figure 2 The XRD diagram of the plant polyphenol carbon dots prepared for Example 1 of the present application;
[0037] Figure 3 The FTIR spectrum of the plant polyphenol carbon dots prepared for Example 1 of the present application;
[0038] Figure 4 The XPS total spectrum (a) and high-resolution spectra of C1s (b), O1s (c) and S2p (d) of the plant polyphenol carbon dots prepared for Example 1 of the present application;
[0039] Figure 5 The Zeta potential diagram of the plant polyphenol carbon dots prepared for Example 1 of the present application;
[0040] Figure 6The fluorescence spectrum of the plant polyphenol carbon dots prepared in Example 1 of the present application; wherein (a) is the excitation spectrum and emission spectrum of the plant polyphenol, (b) is the emission spectrum of the plant polyphenol carbon dots under different excitation wavelengths;
[0041] Figure 7 The cytotoxicity result graph of the plant polyphenol carbon dots prepared in Example 1 of the present application;
[0042] Figure 8 The chelation graph of the plant polyphenol carbon dots prepared in Example 1 of the present application and trivalent iron ions; wherein (a) is the fluorescence intensity F / F0 ratio of the plant polyphenol carbon dots mixed with six single metal ions, (b) is the fluorescence intensity F / F0 ratio of the plant polyphenol carbon dots after adding other metal ions and Fe 3+ , (c) is the fluorescence graph of the chelation ability comparison of the plant polyphenol carbon dots and EDTA and trivalent iron ions, (d) is the ultraviolet absorption graph;
[0043] Figure 9 The iron melting graph of the plant polyphenol carbon dots prepared in Example 1 of the present application and EDTA;
[0044] Figure 10 The plant polyphenol carbon dots prepared in Example 1 of the present application promote the growth of lettuce after chelation with iron, wherein (a) is the growth of lettuce, (b) is the height of lettuce, (c) is the root length of lettuce, (d) is the biomass of lettuce;
[0045] Figure 11 The plant polyphenol carbon dots prepared in Example 1 of the present application improve the chlorophyll content of lettuce after chelation with iron. DETAILED DESCRIPTION
[0046] The various illustrative embodiments of the present application will now be described in detail below, which should not be considered as limiting the present application, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present application.
[0047] It should be understood that the terms described in the present application are only for describing the specific embodiments, and are not used to limit the present application. In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or stated range and any other stated value or intermediate value within the stated range is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.
[0048] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as those of ordinary skill in the art to which the application relates. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described. All documents mentioned herein are incorporated by reference to disclose and describe in full the methods and / or materials which are described therein. In case of conflict between the content of the specification and that of any document incorporated herein by reference, the content of the specification prevails.
[0049] Many modifications and variations of the present application described in the specification are possible without departing from the scope or spirit of the application. Other implementations of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application. The specification and examples are illustrative only.
[0050] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" and the like are open-ended terms that are intended to mean "including but not limited to".
[0051] The purpose of the present application is to provide a preparation and application of plant polyphenol carbon dots with iron carrier function. By taking advantage of the characteristics of plant polyphenols that can react with metal ions, plant polyphenol carbon dots with good water solubility and high efficiency of chelating trivalent iron ions are prepared.
[0052] The present application discloses a preparation method of plant polyphenol carbon dots with iron carrier function, comprising the following steps:
[0053] (1) Dissolve sodium sulfite in water as a solvent;
[0054] (2) Put plant polyphenols into the above solvent and ultrasonic to dissolve, then perform hydrothermal reaction in a high-pressure reaction kettle, centrifuge and filter the obtained solution after cooling to room temperature;
[0055] (3) Dialyze the filtrate obtained in step (2), freeze-dry the dialysate to obtain plant polyphenol carbon quantum dots.
[0056] In some optional embodiments, the plant polyphenols are derived from bark extract, which are purchased from Daxing'anling Lingge Cold Zone Biotechnology Co., Ltd.
[0057] In some optional embodiments, the mass ratio of plant polyphenols to sodium sulfite is 1:(0.1-5), and the solution concentration is 10 mg / mL.
[0058] In some optional embodiments, the temperature of hydrothermal reaction is 160-200℃, and the time is 6-12h.
[0059] In some alternative embodiments, the dialysis bag has a molecular weight cut-off of 200 Da, and the dialysis time is 72-96 h.
[0060] The freeze-drying temperature is -50 to -60 DEG C, and the freeze-drying time is 48-72 h.
[0061] The application further provides the plant polyphenol carbon dots prepared by the preparation method and application thereof in efficient chelation of trivalent iron ions in alkaline soil or lime soil.
[0062] In the application, the ''room temperature'' refers to 20-30 DEG C unless otherwise specified.
[0063] The raw materials used in the application are commercially available.
[0064] The technical solutions of the application are further described below through examples.
[0065] Example 1
[0066] A preparation method of plant polyphenol carbon dots with siderophore function comprises the following steps:
[0067] First, sodium sulfite and plant polyphenols with a mass ratio of 1:1 are dissolved in 60 mL of deionized water in sequence, and the mixture is ultrasonically treated until the plant polyphenols are dissolved, the total concentration of the plant polyphenols and sodium sulfite in the mixture is 10 mg / mL, then the mixed solution obtained by ultrasonic treatment is poured into a 100 mL polytetrafluoroethylene liner, the reaction kettle is placed in a forced air drying oven, and a hydrothermal reaction is carried out at 180 DEG C for 8 h; after the temperature of the reaction kettle decreases to room temperature, the reaction product is centrifuged at 10,000 r for 7 min in a centrifuge, the supernatant is taken and dialyzed in a dialysis bag with a molecular weight cut-off of 200 Da for 72 h, and the solution obtained after dialysis is freeze-dried (the freeze-drying temperature is -60 DEG C, and the freeze-drying time is 48 h) to prepare the plant polyphenol carbon dots.
[0068] Example 2
[0069] The difference from example 1 is that the mass ratio of plant polyphenols to sodium sulfite is 1:0.5, the freeze-drying temperature is -60 DEG C, and the freeze-drying time is 50 h.
[0070] The other preparation processes are the same as those in example 1.
[0071] Example 3
[0072] The difference from example 1 is that the mass ratio of plant polyphenols to sodium sulfite is 1:2, the freeze-drying temperature is -56 DEG C, and the freeze-drying time is 60 h.
[0073] The other preparation processes are the same as those in example 1.
[0074] Effect verification
[0075] 1. The plant polyphenol carbon dots prepared in Example 1 were characterized using various methods:
[0076] (1) The morphology of plant polyphenol carbon dots was observed by transmission electron microscopy (TEM).
[0077] Figure 1 TEM characterization of the plant polyphenol carbon dots prepared in Example 1 of the present invention, with the insets being the HRTEM image and the particle size distribution diagram; Figure 1 It can be seen that the plant polyphenol carbon dots are evenly distributed spherical particles with an average particle size of 2.86 nm. The HRTEM image shows that the lattice spacing of the plant polyphenol carbon dots is 0.21 nm, corresponding to the (100) crystal plane of graphite.
[0078] (2) X-ray diffraction (XRD) was used to characterize the surface structure of plant polyphenol carbon dots.
[0079] Figure 2 This is the XRD pattern of the plant polyphenol carbon dots prepared in Example 1 of the present invention; the X-ray diffraction (XRD) pattern shows that the plant polyphenol carbon dots have a broad peak at 20°, which is classified as an amorphous carbon phase, confirming that the plant polyphenol carbon dots have an amorphous surface structure.
[0080] (3) The chemical composition of plant polyphenol carbon dots was characterized by FTIR.
[0081] Figure 3 This is the FTIR spectrum of the plant polyphenol carbon dots prepared in Example 1 of the present invention; Figure 3 It can be seen from the FTIR spectrum that at 3420 cm -1 A typical strong absorption band is observed at 1619 cm, corresponding to the stretching vibration of OH. -1 The peak at 1189 cm is attributed to the absorption peak of C=O stretching vibration. -1 The peak at 1040 cm corresponds to the stretching vibration absorption of C-S and C-O bonds. -1 were assigned to -SO, CO, and COC bonds. The results indicate that plant polyphenol carbon dots have abundant functional groups, which contributes to their application in biology.
[0082] (4) The elemental composition and elemental chemical state of plant polyphenol carbon dots were characterized by X-ray photoelectron spectroscopy (XPS).
[0083] Figure 4 The XPS total spectrum (a) and high-resolution spectra of C1s (b), O1s (c) and S2p (d) of the plant polyphenol carbon dots prepared in Example 1 of the present invention are shown;Figure 4 The XPS survey spectrum in Figure 19 shows that the plant polyphenol carbon dots are mainly composed of C1s (284.4 eV), O1s (531 eV) and S2p (165 eV), and the fine spectrum of C1s shows different forms of C elements, including C-C (284.8 eV), C-O (286.1 eV) and C=O (289.1 eV), and the fine spectrum of O1s shows that the forms of O elements are C-O (531.6 eV) and C=O (532.9 eV), and in the S2p spectrum, two peaks are identified, with binding energies of 167.9 eV and 169.1 eV, respectively, corresponding to the 2p2 / 1 and 2p3 / 2 peaks of S. The addition of sodium sulfite makes the plant polyphenol carbon dots contain S element, and S is a large amount of element necessary for plant growth, so it can also promote the absorption of S element by plants.
[0084] (5) The plant polyphenol carbon dots were analyzed by zeta potential.
[0085] Figure 5 The zeta potential graph of the plant polyphenol carbon dots prepared in Example 1; through potential analysis, the zeta potential measurement shows that the CDs are negatively charged (ζ = -29.8 mV), which is attributed to many hydroxyl and carboxyl groups on the surface, therefore, the negative charge of the plant polyphenol carbon dots is conducive to its entry into the plant body.
[0086] (6) The optical properties of the plant polyphenol carbon dots were characterized by fluorescence spectrum.
[0087] Figure 6 The fluorescence spectrum of the plant polyphenol carbon dots prepared in Example 1, wherein (a) is the excitation spectrum and emission spectrum of the plant polyphenol, (b) is the emission spectrum of the plant polyphenol carbon dots under different excitation wavelengths, and (c) is the fluorescence spectrum of the plant polyphenol carbon dots under different excitation wavelengths. Figure 6 It can be seen that 320 nm has the maximum excitation spectrum, and shows the maximum emission spectrum at 440 nm. In addition, when the excitation wavelength changes from 300 nm to 500 nm, the emission spectrum shows excitation dependence, which means that there are different emission points on the surface of the CDs.
[0088] II. Cytotoxicity of the plant polyphenol carbon dots prepared in Example 1:
[0089] Method for testing the cytotoxicity of plant polyphenol carbon dots: CCK-8 method was used to determine the cytotoxicity. First, blank control holes and sample addition holes were set in a 96-well plate. The blank holes were added with blank culture medium, and the control holes and sample holes were added with HepG2 cell suspension (cell density was 2×10 4The cells were incubated overnight in the cell incubator after adding PBS water seal to the 96-well four sides and placing in the cell incubator. Then, the old culture medium was aspirated, the sample wells were added with the culture medium containing the sample at a concentration of 50 / 100 / 200 μg / mL, 3 repeated groups were set for each group, the control wells were added with the normal culture medium solution, the blank wells were added with the culture medium, and the treated cells were cultured in the incubator at 37°C and 5% CO2 for 24 h. Finally, 10 μl of CCK8 solution was added after the cells reached the incubation time, the incubator was set to 37°C and 5% CO2, and the absorbance value was detected at 450 nm after incubation for 1 h.
[0090] Figure 7 The cytotoxicity result graph of the plant polyphenol carbon dots prepared in Example 1 of the present application; after calculation, the cell activity can reach 90% when the concentration of the plant polyphenol carbon dots is as high as 200 μg / mL, therefore, the results show that the plant polyphenol carbon dots have low toxicity. Figure 7 It can be seen that when the concentration of the plant polyphenol carbon dots is as high as 200 μg / mL, the cell activity can reach 90%, therefore, the results show that the plant polyphenol carbon dots have low toxicity.
[0091] III. Specific chelating ability of the plant polyphenol carbon dots prepared in Example 1 and trivalent iron ions:
[0092] The plant polyphenol carbon dots were chelated with iron: 0.2 g of plant polyphenol carbon dots and 0.1 M of ferric chloride were stirred on a magnetic stirrer for 8 h, then centrifuged, washed with deionized water for 3 times, and freeze-dried to prepare the chelate.
[0093] The chelating ability of the plant polyphenol carbon dots and trivalent iron ions was characterized by fluorescence spectrum and ultraviolet absorption graph.
[0094] Figure 8 The plant polyphenol carbon dots prepared in Example 1 of the present application and trivalent iron ion chelation graph, wherein (a) is the fluorescence intensity F / F0 ratio of the plant polyphenol carbon dots mixed with six single metal ions, (b) is the fluorescence intensity F / F0 ratio of the plant polyphenol carbon dots after adding other metal ions and Fe 3+ The plant polyphenol carbon dots fluorescence intensity F / F0 ratio; and the fluorescence graph (c) and ultraviolet absorption graph (d) of the plant polyphenol carbon dots and EDTA and trivalent iron ion chelating ability comparison; from Figure 8 It can be seen that calcium ions, potassium ions, etc. cannot reduce the fluorescence of the plant polyphenol carbon dots, but the fluorescence intensity is reduced after chelation with trivalent iron ions, which shows that the plant polyphenol carbon dots can specifically chelate with trivalent iron ions. At the same time, from Figure 8It can also be found that the addition of EDTA (ethylenediaminetetraacetic acid) does not affect the fluorescence intensity of the plant polyphenol carbon dots, but the addition of ferric ions reduces the fluorescence intensity, indicating that the chelating ability of the plant polyphenol carbon dots with ferric ions is stronger than that of EDTA with ferric ions; in addition, the ultraviolet absorption graph can further prove that the ultraviolet absorption curve does not decrease after the addition of EDTA. Therefore, the results show that the plant polyphenol carbon dots can specifically chelate with ferric ions, and the chelating ability is greater than that of EDTA.
[0095] Four, the iron melting ability of the plant polyphenol carbon dots prepared in Example 1:
[0096] The content of divalent iron is determined by the o-phenanthroline method. The specific test process is as follows:
[0097] First, the same mass of plant polyphenol carbon dots and EDTA is respectively cultured with the same mass of ferric hydroxide in a shaking incubator for 48h, the supernatant after culture is reacted with o-phenanthroline, and the absorption value at 510nm is determined by ultraviolet spectrophotometer, and the absorption value at 510nm of the unreacted supernatant is also determined to exclude the influence of the carbon dots themselves.
[0098] Figure 9 The iron melting graph of the plant polyphenol carbon dots prepared in Example 1 and EDTA; from Figure 9 It can be seen from the figure that the ultraviolet absorption value of the plant polyphenol carbon dots is greater than that of EDTA, so the plant polyphenol carbon dots can dissolve the insoluble iron from the ferric hydroxide and reduce it to divalent iron.
[0099] Five, the plant polyphenol carbon dots prepared in Example 1 promote the growth of lettuce under iron deficiency conditions after chelating with ferric ions.
[0100] The treatment method of the chelate of plant polyphenol carbon dots and ferric ions to lettuce seedlings:
[0101] First, select the seeds of the lettuce with full and uniform grains, soak them in 3% hydrogen peroxide solution for 20min, then sterilize them with 75% anhydrous ethanol for about 10s, and then rinse them with distilled water for 3 times. The sterilized seeds are soaked in distilled water for 24h in the dark, and then sowed in vermiculite for germination, and then transplanted when the two cotyledons of the lettuce seedlings are unfolded. Select the seedlings with similar growth to transplant into 1 / 2 Hoagland nutrient solution under iron deficiency, and cultivate in a greenhouse (cultivation conditions: 16h light per day, 8h darkness, temperature 30℃ (day) / 25℃ (night)), 4 seedlings per pot, and set three groups of repeats. After 6 cotyledons, add different concentrations (5mg L -1 , 10mg L -1 , 20mg L -1The plant polyphenol carbon dots prepared in Example 1 were chelated with ferric iron, and after 14 days of treatment, the lettuce seedlings were sampled, and various growth indicators of the lettuce seedlings were recorded.
[0102] Figure 10 Figure for promoting lettuce growth after chelating the plant polyphenol carbon dots prepared in Example 1 with iron; wherein (a) is the growth of lettuce, (b) is the height of lettuce, (c) is the root length of lettuce, and (d) is the biomass of lettuce; from the figure, the effect of the chelate of plant polyphenol carbon dots and ferric iron on the growth of lettuce seedlings can be seen: after 14 days of culture by adding different concentrations of chelate into the nutrient solution, the growth of lettuce seedlings was observed, and various growth parameters of lettuce seedlings were recorded. Figure 10 It can be seen that, compared with the control group, the growth of lettuce seedlings with chelate is better, and various growth parameters of lettuce seedlings are recorded, from which Figure 10 It can be seen that, compared with the control group, the height, root length, fresh weight and dry weight of the lettuce seedlings treated with plant polyphenol carbon dots have significant differences. Specifically, compared with the control group, the height of the lettuce seedlings increased by 27.8%, 34.5% and 19.3%, respectively, the root length increased by 4.9%, 7.4% and 5.9%, respectively, and the biomass of the lettuce seedlings increased by 34.48%, 41.85% and 36.77%, respectively (p<0.05). These results show that the chelate prepared in the present application can effectively improve the iron absorption of lettuce seedlings, thereby promoting the growth of lettuce seedlings.
[0103] Six, the plant polyphenol carbon dots prepared in Example 1 were chelated with ferric iron to improve the chlorophyll content of lettuce seedlings.
[0104] Method for determining photosynthetic pigment content of lettuce seedlings:
[0105] 0.05 g of fresh leaves of lettuce seedlings were weighed, and a mixture of acetone and anhydrous ethanol was used for dark extraction for 24 h. After mixing, the supernatant was poured into a cuvette, and the absorbance values at 470 nm, 645 nm and 663 nm were measured by ultraviolet spectrophotometry to calculate the content of photosynthetic pigments.
[0106] Figure 11 Figure for improving the chlorophyll content of lettuce after chelating the plant polyphenol carbon dots prepared in Example 1 with iron, from which the effect of plant polyphenol carbon dots on the accumulation of chlorophyll content in lettuce seedlings can be seen: compared with the control group, the accumulation of photosynthetic pigment content in lettuce seedlings treated with chelate was significantly improved, increased by 38.43%, 35.92% and 46.53%, respectively. Therefore, the chelate helps the iron absorption of lettuce seedlings under iron deficiency conditions, thereby promoting the synthesis and accumulation of chlorophyll.
[0107] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.
Claims
1. A method for preparing plant polyphenol carbon dots with siderophore function, characterized in that: The following steps are involved: dissolving plant polyphenols and sodium sulfite in water to obtain a mixed solution; The mixed solution is sequentially subjected to hydrothermal reaction, cooling, centrifugation, filtration, dialysis and freeze-drying to obtain the plant polyphenol carbon dots.
2. The method for preparing plant polyphenol carbon dots with siderophore function according to claim 1, characterized in that: The mass ratio of the plant polyphenols to sodium sulfite is 1:(0.1-5).
3. The method for preparing plant polyphenol carbon dots with siderophore function according to claim 1, characterized in that: The total concentration of plant polyphenols and sodium sulfite in the mixed solution is 10 mg / mL.
4. The method for preparing plant polyphenol carbon dots with siderophore function according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 160-200° C., and the time of the hydrothermal reaction is 6-12 hours.
5. The method for preparing plant polyphenol carbon dots with siderophore function according to claim 1, characterized in that: The molecular weight cut-off of the dialysis bag used in the dialysis process is 200 Da, and the dialysis time is 72 h to 96 h.
6. The method for preparing plant polyphenol carbon dots with siderophore function according to claim 1, characterized in that: The freeze-drying process is carried out under the following conditions: freeze-drying at -50 to -60°C for 48 to 72 hours.
7. A plant polyphenol carbon dot with siderophore function, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 6.
8. The plant polyphenol carbon dots with siderophore function according to claim 7, characterized in that: The average particle size of the plant polyphenol carbon dots with siderogenicity is 2.86 nm.
9. The plant polyphenol carbon dots with siderophore function according to claim 7, characterized in that: The negative charge of the plant polyphenol carbon dots with siderophore function is -29.8 mV.
10. Use of the plant polyphenol carbon dots with siderophore function as claimed in any one of claims 7 to 9 in promoting plant growth, characterized in that: The plant polyphenol carbon dots with iron carrier function promote the growth of plants under iron-deficient conditions after chelating with trivalent iron.