Preparation method and application of an iron-based polyphenol carbon dot composite material

Abstract

This invention provides a method for preparing an iron-based polyphenol carbon dot composite material, comprising: mixing a ferric chloride hexahydrate solution with a nano-ferric oxide dispersion and stirring to obtain a reaction solution; adding a tannic acid solution to the reaction solution, heating, transferring the reacted solution to a dialysis bag for dialysis and centrifugation, collecting the solid, and obtaining the iron-based polyphenol carbon dot composite material. The iron-based polyphenol carbon dot composite material prepared by the above method can be used to promote soybean seed germination and seedling growth under abiotic stress. Specifically, the method involves: dissolving the iron-based polyphenol carbon dot composite material in a solvent to prepare a seed soaking solution; and immersing soybean seeds in the seed soaking solution. The Fe2O3@FeTA-CDs synthesized by this invention have advantages such as simple preparation process, high yield, low cost, and good material dispersibility. This invention, combined with seed treatment technology, can significantly promote soybean seed germination, growth, and stress resistance, and has advantages such as simple operation, significant effect, low cost, and ease of promotion.

Description

Technical Field

[0001] This invention belongs to the field of crop cultivation technology, specifically relating to a method for preparing and applying an iron-based polyphenol carbon dot composite material. Background Technology

[0002] Human activities and climate change are exacerbating the impact of extreme abiotic stresses such as drought, salt stress, and low temperatures on plants. These stressors severely affect plant physiological and biochemical processes, hindering growth and development, and consequently causing significant losses in yield and biodiversity. Therefore, exploring methods to improve crop germination rates and resilience to adversity is crucial for increasing crop yields and developing sustainable ecosystems.

[0003] Soybeans are one of the world's most important dual-purpose crops, serving as both a source of high-quality plant protein and edible oil for humans, and a crucial source of feed protein for livestock. Currently, soybean applications are diversified, extending beyond traditional food processing and oil extraction into a intensive processing industry chain, with increasingly widespread applications in protein products, biofuels, and pharmaceuticals. However, against the backdrop of global climate change, frequent extreme stresses severely restrict soybean growth, development, and production potential. Drought, salinity, and high temperatures can delay or even inhibit seed germination, leading to uneven emergence. These stresses further inhibit cell elongation, resulting in stunted plants, wilted leaves, and reduced leaf area, thus lowering photosynthetic efficiency. Especially during flowering, pod formation, and grain filling stages, abiotic stresses can cause significant flower and pod drop, hindered grain filling, decreased 100-grain weight, and ultimately, a sharp reduction in yield. Simultaneously, extreme abiotic stresses can also affect the nitrogen-fixing activity of rhizobia, reducing nitrogen supply and exacerbating premature plant senescence. Therefore, improving the germination rate and stress resistance of soybeans, and enhancing their ability to survive under extreme climatic conditions, is crucial for maintaining their growth, development, yield, and quality.

[0004] Based on this, the present invention provides an iron-based polyphenol carbon dot composite material, which is used to promote soybean seed germination and growth under abiotic stresses such as drought and salinity. It can effectively alleviate the adverse effects of extreme abiotic stresses on soybean seed growth and improve the stress resistance of soybeans, in order to contribute to the promotion of sustainable agricultural development. Summary of the Invention

[0005] This invention addresses the problems existing in the prior art by providing a method for preparing an iron-based polyphenol carbon dot composite material, and the application of this iron-based polyphenol carbon dot composite material in promoting soybean seed germination and seedling growth under abiotic stress, which can improve the germination rate of soybean seeds and the seedling vigor index under abiotic stress.

[0006] The present invention adopts the following technical solution:

[0007] This invention provides a method for preparing an iron-based polyphenol carbon dot composite material, comprising the following steps: S1. Mix the ferric chloride hexahydrate solution with the nano ferric oxide dispersion, stir and react to obtain the reaction solution; S2. Add tannic acid solution to the reaction solution, heat to react, transfer the reaction solution to a dialysis bag for dialysis, centrifuge the dialyzed liquid, collect the solid, and obtain iron-based polyphenol carbon dot composite material.

[0008] Furthermore, the mass ratio of the nano-ferric oxide, ferric chloride hexahydrate, and tannic acid is 0.5~1 g: 0.1~0.2 g: 1.25~2.5 g.

[0009] Furthermore, the ferric chloride hexahydrate solution is prepared by dissolving ferric chloride hexahydrate in deionized water, with a concentration of 4.0~8.0 g / L; the tannic acid solution is prepared by dissolving tannic acid in deionized water, with a concentration of 12.5~25.0 g / L; and the nano-ferric oxide dispersion is prepared by ultrasonically dispersing nano-ferric oxide particles in an ethanol solution, with a concentration of 5.0~10.0 g / L.

[0010] Furthermore, in step S1, the stirring reaction time is 20-60 min, preferably 30 min.

[0011] Furthermore, in step S2, the heating reaction temperature is 180~250 °C, preferably 200 °C, and the reaction time is 12~48 h, preferably 24 h.

[0012] Furthermore, in step S2, the dialysis time is 48~72 h.

[0013] (ii) The present invention also provides the application of the iron-based polyphenol carbon dot composite material prepared by the above preparation method in promoting soybean seed germination and seedling growth under abiotic stress.

[0014] Furthermore, the application method is as follows: dissolve the iron-based polyphenol carbon dot composite material in a solvent to prepare a soaking solution; place soybean seeds in the soaking solution for soaking treatment.

[0015] Furthermore, the concentration of the iron-based polyphenol carbon dot composite material in the soaking solution is greater than 0 and not greater than 100 mg / L, more preferably 25 mg / L; the ratio of soybean seeds to the soaking solution is 1 g: 3~20 mL, preferably 1 g: 5 mL; the soaking time is 12~48 h, preferably 24 h, and the soaking temperature is 20~30 °C.

[0016] Furthermore, the abiotic stress is at least one of salt stress, drought stress, low temperature stress, or heavy metal stress.

[0017] The beneficial effects of this invention are: The iron-based polyphenol carbon dot composite material (Fe2O3@FeTA-CDs) provided by this invention has a simple preparation process, requiring no complex equipment or harsh reaction conditions, and is easy to scale up for production. This material exhibits good dispersibility in water, forming a stable and uniform seed soaking solution, which is beneficial for its uniform application in seed treatment. Due to its short preparation process and controllable raw material costs, this method is highly cost-effective and suitable for promotion in agricultural production. Under drought and saline-alkali stress conditions, experimental results showed that this material significantly improved the germination rate, shoot length, and seed vigor index of soybean seeds. This indicates that Fe2O3@FeTA-CDs can effectively alleviate the inhibition of seed germination caused by osmotic stress and ion toxicity, and promote early seedling growth. This material is effective, easy to operate, and economically feasible, showing great potential for application and promotion. Attached Figure Description

[0018] Figure 1 Scanning electron microscope image of Fe2O3@FeTA-CDs prepared in Example 1; Figure 2 The effects of different concentrations of Fe2O3@FeTA-CDs on soybean seed germination and growth under normal growth conditions were investigated. Among them, (A) represents germination rate; (B) represents sprout length; and (C) represents vigor index. Figure 3 Example 3 illustrates the effects of different treatment groups on soybean seed germination and growth under drought stress, where (A) represents germination rate; (B) represents sprout length; and (C) represents vigor index. Figure 4 Example 4 illustrates the effects of different treatment groups under salt stress on soybean seed germination and growth, where (A) represents germination rate; (B) represents sprout length; and (C) represents vigor index. Figure 5 This is a comparison of germination lengths of Fe2O3@FeTA-CDs and deionized water under normal conditions, drought stress, and salt stress. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1 This invention provides a method for preparing an iron-based polyphenol carbon dot composite material, comprising the following steps: 1.0 g of nano-ferric oxide particles were ultrasonically dispersed in 100 mL of ethanol solution (50%) and stirred to obtain a nano-ferric oxide dispersion with a concentration of 10.0 g / L; 0.2 g of ferric chloride hexahydrate was dissolved in 25 mL of deionized water to obtain a ferric chloride hexahydrate solution with a concentration of 8.0 g / L; 2.0 g of tannic acid was dissolved in 100 mL of deionized water to obtain a tannic acid solution with a concentration of 20.0 g / L.

[0021] Ferric chloride hexahydrate solution was mixed with nano-ferric oxide dispersion and stirred continuously for 30 min to allow the reaction to proceed fully, resulting in a reaction solution. Tannic acid solution was slowly added dropwise to the reaction solution while stirring continuously. The resulting mixture was transferred to a reaction vessel and reacted at 200 °C for 24 h. The resulting solution was then transferred to a dialysis bag and dialyzed continuously until the physicochemical properties of the solution outside the dialysis bag no longer changed. The dialyzed liquid was centrifuged, the solid was collected, washed with water and ethanol, and then freeze-dried to obtain the iron-based polyphenol carbon dot composite material (Fe2O3@FeTA-CDs).

[0022] Figure 1 This is a scanning electron microscope (SEM) image of Fe2O3@FeTA-CDs. (Source: [Insert image here]) Figure 1 It can be seen that the synthesized Fe2O3@FeTA-CDs are spherical in shape, with a rough surface, good dispersibility, and a particle size of about 50 nm.

[0023] Example 2—Germination test of Fe2O3@FeTA-CDs soaking solution of different concentrations The iron-based polyphenol carbon dot composite material prepared in Example 1 was used to conduct a soybean seed germination test. The specific method is as follows: 1. Preparation of soaking solution: A certain amount of Fe2O3@FeTA-CDs prepared in Example 1 was weighed using an analytical balance and dissolved in deionized water. The solution was then ultrasonically dispersed for 30 minutes to prepare suspensions with concentrations of 25, 50, and 100 mg / L, respectively, resulting in three different concentrations of soaking solution.

[0024] 2. Germination Experiment Using soybean variety "Huaxia 21" as the experimental material, uniformly sized and plump soybean seeds were selected, while shriveled and damaged seeds were removed. The selected soybean seeds were disinfected with 5% sodium hypochlorite for 10 min, and then rinsed thoroughly with deionized water. The seeds were then soaked in Fe2O3@FeTA-CDs suspensions at concentrations of 25, 50, and 100 mg / L for 24 h, with a seed mass to soaking solution volume ratio of 1 g: 5 mL.

[0025] After soaking, the seeds were removed, rinsed with deionized water, and then placed in petri dishes (15 cm in diameter) lined with filter paper. Ten seeds were placed in each petri dish, and 3 mL of deionized water was added. Each treatment was set up in quadruplicate, and the seeds were placed in a dark incubator at 25 °C for 7 days to germinate. The germination rate and vigor index of soybean seeds for each treatment were recorded.

[0026] The statistical method is as follows: Germination rate: A seed is considered to have germinated if its bud or root length exceeds half the length of the seed. The germination rate is calculated by counting the proportion of germinated seeds out of all soybean seeds in the petri dish.

[0027] Vigor Index: The seed vigor index is calculated by measuring the bud and root length of the seedlings with a millimeter ruler. Seed vigor index = (root length + bud length) × germination rate (cm).

[0028] Figure 2 The effect of different concentrations of Fe2O3@FeTA-CDs on the germination and growth of soybean seeds under normal growth conditions in Example 1 is shown. (A) is the germination rate; (B) is the length of the bean sprout; and (C) is the vigor index.

[0029] Depend on Figure 2 It can be seen that soaking soybean seeds with different concentrations of Fe2O3@FeTA-CDs generally increased the germination rate, showing a trend that lower concentrations had a better promoting effect than higher concentrations, with 25 mg / L showing the best performance and a germination rate of over 90%. Figure 2 A). From Figure 2 As shown in Figure B, the 25 mg / L Fe2O3@FeTA-CDs treatment significantly increased the length of bean sprouts, by 27.4% compared to the control. Simultaneously, the 25 mg / L Fe2O3@FeTA-CDs treatment significantly improved the seed vigor index, increasing it by 47.2% compared to the control. Figure 2 C). Figure 5It is clearly evident that, compared to the water-initiated group, treatment with 25 mg / L Fe2O3@FeTA-CDs significantly increased soybean sprout length. When the Fe2O3@FeTA-CDs concentration reached 50 mg / L and 100 mg / L, the sprout length and vigor index decreased slightly compared to 25 mg / L. Therefore, within a certain concentration range, Fe2O3@FeTA-CDs soaking treatment can promote soybean seed germination and growth. Based on these results, 25 mg / L was ultimately selected as the optimal concentration for subsequent experiments.

[0030] Example 3—The effect of Fe2O3@FeTA-CDs soaking solution on soybean seed germination under drought stress The iron-based polyphenol carbon dot composite material prepared in Example 1 was used to conduct a soybean seed germination test. The specific method is as follows: A Fe2O3@FeTA-CDs suspension with a concentration of 25 mg / L was prepared according to the method in Example 1 and used as the soaking solution.

[0031] Using the soybean variety "Huaxia 21" as the experimental material, soybean seeds of uniform size and plumpness were selected, while shriveled and damaged seeds were removed. The selected soybean seeds were disinfected with 5% sodium hypochlorite for 10 minutes, and then rinsed thoroughly with deionized water.

[0032] Soybean seeds were divided into experimental group, control group, and blank group. Experimental group: drought stress + soaking in 25 mg / L Fe2O3@FeTA-CDs seed soaking solution for 24 h, material-to-liquid ratio 1 g: 5 mL; Control group: drought stress + soaking in deionized water for 24 h, material-to-liquid ratio 1 g: 5 mL; Blank group: Normal conditions + soaking in deionized water for 24 h, material-to-liquid ratio 1 g: 5 mL.

[0033] Soybean seeds from the experimental group, control group, and blank group were soaked and placed in petri dishes (15 cm in diameter) lined with filter paper, with 10 seeds in each dish. The blank group received 3 mL of deionized water, while the experimental and control groups each received 3 mL of 7.5 w / v% PEG solution. Each treatment was replicated in four places, and the seeds were germinated in a dark incubator at 25°C for 7 days. Germination rate and vigor index of soybean seeds for each treatment were calculated according to the method in Example 2.

[0034] Figure 3 Effects of Fe2O3@FeTA-CDs soaking on germination rate (A), sprout length (B), and vigor index (C) of soybean seeds under simulated drought stress in 7.5% polyethylene glycol (PEG).

[0035] Depend on Figure 3 It can be seen that drought stress significantly reduced the germination rate, sprout length, and vigor index of soybean seeds. However, treatment with 25 mg / L Fe2O3@FeTA-CDs significantly increased the germination rate of soybean seeds (8.3%). Figure 3 A) Bean sprout length (32.8%) Figure 3 B) and seed vigor index (42.5%) Figure 3 C). Figure 5 It is clearly visible that, compared to the control group, the treatment with Fe2O3@FeTA-CDs significantly increased the length of bean sprouts.

[0036] Therefore, the Fe2O3@FeTA-CDs soaking treatment improved the germination rate, sprout length, and vigor index of soybean seeds under drought stress, thus enhancing the drought resistance of soybean seeds under drought stress.

[0037] Example 4—Effect of Fe2O3@FeTA-CDs soaking solution on soybean seed germination under salt stress The iron-based polyphenol carbon dot composite material prepared in Example 1 was used to conduct a soybean seed germination test. The specific method is as follows: A Fe2O3@FeTA-CDs suspension with a concentration of 25 mg / L was prepared according to the method in Example 1 and used as the soaking solution.

[0038] Using the soybean variety "Huaxia 21" as the experimental material, soybean seeds of uniform size and plumpness were selected, while shriveled and damaged seeds were removed. The selected soybean seeds were disinfected with 5% sodium hypochlorite for 10 minutes, and then rinsed thoroughly with deionized water.

[0039] Soybean seeds were divided into experimental group, control group, and blank group. Experimental group: Salt stress + soaking in 25 mg / L Fe2O3@FeTA-CDs soaking solution for 24 h, material-to-liquid ratio 1 g: 5 mL; Control group: Salt stress + soaking in deionized water for 24 h, material-to-liquid ratio 1 g: 5 mL; Blank group: Normal conditions + soaking in deionized water for 24 h, material-to-liquid ratio 1 g: 5 mL.

[0040] Soybean seeds from the experimental group, control group, and blank group were soaked and placed in petri dishes (15 cm in diameter) lined with filter paper, with 10 seeds in each dish. The blank group received 3 mL of deionized water, while the experimental and control groups each received 3 mL of 100 mM NaCl solution. Each treatment was replicated in four places, and the seeds were germinated in a dark incubator at 25°C for 7 days. The germination rate and vigor index of the soybean seeds for each treatment were calculated according to the method in Example 2.

[0041] Figure 4 Effects of soaking Fe2O3@FeTA-CDs on germination rate (A), sprout length (B), and vigor index (C) of soybean seeds under simulated salt stress of 100 mM NaCl.

[0042] Depend on Figure 4 It can be seen that salt stress significantly reduced the germination rate, sprout length, and vigor index of soybean seeds. However, after soaking in Fe2O3@FeTA-CDs, the germination rate of soybean seeds was significantly increased (9.9%). Figure 4 A) Bean sprout length (29.7%) Figure 4 B) and seed vigor index (56.6%) Figure 4 C). Figure 5 It is clearly visible that, compared to the control group, the treatment with Fe2O3@FeTA-CDs significantly increased the length of bean sprouts.

[0043] Therefore, Fe2O3@FeTA-CDs soaking treatment improved the germination rate, sprout length and vigor index of soybean seeds under salt stress, thus enhancing the growth resilience of soybean seeds under salt stress.

[0044] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an iron-based polyphenol carbon dot composite material, characterized in that, Includes the following steps: S1. Mix the ferric chloride hexahydrate solution with the nano ferric oxide dispersion, stir and react to obtain the reaction solution; S2. Add tannic acid solution to the reaction solution, heat to react, transfer the reaction solution to a dialysis bag for dialysis, centrifuge the dialyzed liquid, collect the solid, and obtain iron-based polyphenol carbon dot composite material.

2. The method for preparing the iron-based polyphenol carbon dot composite material according to claim 1, characterized in that, The mass ratio of nano-ferric oxide, ferric chloride hexahydrate, and tannic acid is 0.5~1 g: 0.1~0.2 g: 1.25~2.5 g.

3. The method for preparing the iron-based polyphenol carbon dot composite material according to claim 1, characterized in that, The ferric chloride hexahydrate solution is prepared by dissolving ferric chloride hexahydrate in deionized water, with a concentration of 4.0~8.0 g / L; The tannic acid solution is prepared by dissolving tannic acid in deionized water, and has a concentration of 12.5~25.0 g / L; The nano-ferric oxide dispersion was prepared by ultrasonically dispersing nano-ferric oxide particles in an ethanol solution, with a concentration of 5.0~10.0 g / L.

4. The method for preparing the iron-based polyphenol carbon dot composite material according to claim 1, characterized in that, In step S1, the stirring reaction time is 20~60 min.

5. The method for preparing the iron-based polyphenol carbon dot composite material according to claim 1, characterized in that, In step S2, the heating temperature is 180~250 °C and the reaction time is 12~48 h.

6. The method for preparing the iron-based polyphenol carbon dot composite material according to claim 1, characterized in that, In step S2, the dialysis time is 48-72 hours.

7. The application of the iron-based polyphenol carbon dot composite material prepared by the preparation method according to any one of claims 1 to 6 in promoting soybean seed germination and seedling growth under abiotic stress.

8. The application according to claim 7, characterized in that, The application method is as follows: Iron-based polyphenol carbon dot composite material was dissolved in a solvent to prepare a seed soaking solution; Soybean seeds are soaked in the soaking solution.

9. The application according to claim 8, characterized in that, The concentration of the iron-based polyphenol carbon dot composite material in the soaking solution is greater than 0 and not greater than 100 mg / L; The ratio of soybean seeds to soaking solution is 1 g: 3~20 mL; Soaking time is 12~48 h, and soaking temperature is 20~30 °C.

10. The application according to claim 7, characterized in that, The abiotic stress is at least one of salt stress, drought stress, low temperature stress, or heavy metal stress.

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