Composition for preparing coating agent and application thereof

Abstract

The invention provides a composition for preparing a coating agent and application of the composition. The composition comprises sodium deoxycholate (NaDC), polyamine and water. The seed coating agent with high film-forming property and high entrapment property can be obtained by utilizing a water-based liquid-liquid condensed phase prepared from the composition. More importantly, the raw materials of the composition are simple, non-toxic and wide in source, the method for preparing the coating agent is simple and rapid, and the obtained coating agent is good in wrapping performance. Furthermore, other seed protective agents can be wrapped in the composition, so that the composition is wide in application and has a huge application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of seed coating, and mainly relates to a composition for preparing a coating agent and application thereof. Background Art

[0002] Seeds are the foundation of crop growth and development, the very foundation of our national survival, and play an irreplaceable strategic role in agricultural production. Seed germination is highly sensitive to its surrounding environment. Soil nutrients, moisture content, pests and diseases, and temperature all influence germination and subsequent growth, ultimately impacting the yield and quality of mature crops. However, land degradation, excessive freshwater consumption, the misuse of agrochemicals, global climate change, and the spread of pests and diseases pose serious threats to seed germination and crop growth and development. Therefore, there is an urgent need to enhance seed vigor, stress resistance, and resilience to adapt to the rapidly changing agricultural production environment.

[0003] Seed coating is a common strategy in modern agriculture for protecting seedlings during their initial development. It involves evenly coating the seed coat with a coating containing nutrients, growth regulators, fungicides, insecticides, and beneficial microorganisms, forming a protective layer with specific functionality and strength. Seed coating not only shortens or prolongs seed germination time, protects crops from abiotic and biotic stresses, but also improves the effectiveness of pesticide application. Therefore, using seed coating technology to improve the seed growth microenvironment has a profound impact on increasing grain yield, quality, and safety, as well as promoting sustainable agricultural development.

[0004] Currently, seed coating mainly involves two methods: seed pelleting and seed film coating. These methods use adhesives or film-forming agents (polymers) to adhere or coat active ingredients such as nutrients, fungicides, and pesticides onto the outside of the seeds, forming a protective layer. However, these methods often involve complex preparation processes, use toxic solvents, and consume high energy. Furthermore, excessively thick coatings can hinder seed respiration and germination. Consequently, the development and widespread application of simple, efficient, low-cost, environmentally friendly, and multifunctional seed coating formulations and methods are still lacking.

[0005] In summary, the existing seed coating agents have the following technical problems:

[0006] 1. Existing seed coating methods and seed coating agents are single and cannot meet the complex and changeable seed germination and growth environment;

[0007] 2. Existing coating methods involve complex preparation processes, use toxic solvents, are energy-intensive, and excessively thick coatings can hinder seed respiration and germination.

[0008] 3. There is a lack of seed coating systems and coating methods that can simultaneously promote seed germination, resist frost, resist pathogenic fungi and be environmentally friendly.

[0009] Therefore, it is necessary to improve the existing coating agent. Summary of the Invention

[0010] In order to solve the above technical problems, the present invention provides a composition for preparing a coating agent, which comprises: bile salt sodium deoxycholate (NaDC), polyamine and water.

[0011] According to an embodiment of the present invention, the polyamine is selected from divalent, trivalent and higher polyamines, for example, at least one of spermine, spermidine, diethylenetriamine, 1,3-diaminopropane, 1,5-diaminopentane, 1,7-diaminoheptane and 1,9-diaminononane.

[0012] According to an embodiment of the present invention, the molar ratio of sodium deoxycholate to polyamine is 1:0.8 to 1:13, for example 1:1 to 1:10, such as 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10.

[0013] According to an embodiment of the present invention, the amount of water used is such that the concentration of sodium deoxycholate is 0.5-100 mM, for example 5-80 mM, such as 10 mM, 20 mM, 30 mM, 40 mM, or 50 mM.

[0014] According to an embodiment of the present invention, the composition further comprises seed protectants, such as plant growth regulators, fungicides, insecticides and biological agents, for example, nutrients such as indolebutyric acid (IA) and gibberellin (GB).

[0015] The present invention also provides use of the composition described above in preparing a seed coating agent.

[0016] The present invention also provides a method for preparing a seed coating agent using the above composition, comprising:

[0017] Aqueous solutions of NaDC and polyamine are prepared separately and then mixed to obtain a liquid-liquid coacervate phase.

[0018] The present invention also provides a method for preparing coated seeds using the composition as described above, comprising:

[0019] Aqueous solutions of NaDC and polyamine are prepared separately and then mixed to obtain a liquid-liquid coacervate phase; seeds are immersed in the liquid-liquid coacervate phase and then taken out to obtain the product.

[0020] According to an embodiment of the present invention, the above operation is carried out at 0-50°C, such as 0-30°C.

[0021] According to an embodiment of the present invention, the molar ratio of NaDC to polyamine is 1:0.8 to 1:13, for example 1:1 to 1:10, such as 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10.

[0022] According to an embodiment of the present invention, the concentrations of the aqueous solutions of NaDC and polyamines are the same or different and are independently 0.5-100 mM; for example 5-80 mM; such as 10 mM, 20 mM, 30 mM, 40 mM, 50 mM.

[0023] According to an embodiment of the present invention, the soaking time is more than 5 seconds, for example, 10 seconds to 12 hours.

[0024] According to an embodiment of the present invention, the seeds are any plant seeds existing in nature, for example, crop seeds, such as wheat seeds and cowpea seeds.

[0025] According to an embodiment of the present invention, the method further comprises the step of taking out the seeds and drying them after soaking.

[0026] The present invention also provides coated seeds prepared by the above method.

[0027] The composition of the present invention has the following advantages:

[0028] 1. The preparation is simple, and the formula can be adjusted through simple blending and compounding; 2. The raw materials are environmentally friendly and safe, and the seed coating agent is prepared using bio-friendly surfactants and polyamines; 3. The method for preparing the coating using the composition is novel and unique, and a seed coating agent with high film-forming and high encapsulation properties can be obtained using a water-based liquid-liquid coacervate phase; 4. The speed of coating seeds using the composition is fast, and the coating process can be completed by soaking the seeds in the water-based liquid-liquid coacervate phase prepared by the composition for 5 seconds; 5. The coating system prepared by the composition can effectively improve the seed growth microenvironment, and at the same time has the functions of promoting seed germination and growth, resisting plant pathogens and antifreeze. In addition, the high encapsulation performance of the liquid-liquid coacervate phase is used to encapsulate other active ingredients to give the seed coating agent more functions.

[0029] In summary, the present invention creatively utilizes a water-based liquid-liquid coacervate phase to produce a seed coating agent with high film-forming and high encapsulation properties. More importantly, the composition of the present invention utilizes simple, non-toxic, and widely available raw materials, and the preparation method is simple and rapid, resulting in excellent encapsulation performance. Furthermore, the composition can also be used to encapsulate other seed protection agents, thus possessing a wide range of applications and promising prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1Turbidity curves and phase boundaries of sodium deoxycholate / polyamines. (a) Turbidity curves of sodium deoxycholate titrated with spermidine or spermine at concentrations of 5 / 10 / 20 / 30 / 40 / 50 mM. (b) Phase boundaries of phase transitions of sodium deoxycholate / spermidine and sodium deoxycholate / spermine mixtures.

[0031] Figure 2 Liquid-liquid coacervates of sodium deoxycholate and spermidine or spermine. (a) Chemical structures of sodium deoxycholate, spermidine, and spermine. (b) Cryo-transmission electron microscopy image of micelles in a 20 mM sodium deoxycholate solution. (c) Optical microscopy and (d) cryo-scanning electron microscopy images of coacervate droplets in a 20 mM sodium deoxycholate / 20 mM spermidine or spermine mixed solution.

[0032] Figure 3 Cross-section of the coating obtained by immersing cowpea seeds in 10 mM sodium deoxycholate / 10 mM spermidine and 10 mM sodium deoxycholate / 10 mM spermine liquid-liquid coacervate phases.

[0033] Figure 4 The sodium deoxycholate / polyamine liquid-liquid coacervate shortens seed treatment time. Germination (a), germination rate (b), and sprout length (c) of wheat and cowpea seeds treated at 25°C on day 4. Numbers 1-6 in each panel represent the following seed treatments: 1) three water soaks for 4 hours; 2) soaks with a 3 mg / L commercial adjuvant for 4 hours; 3) soaks with a solution containing a plant growth hormone (gibberellic acid or indolebutyric acid) for 10 seconds; 4) soaks with a solution containing a plant growth hormone (100 mg / L gibberellin or indolebutyric acid) for 4 hours; 5) soaks with 10 mM sodium deoxycholate / 10 mM spermidine plus a plant growth hormone (100 mg / L gibberellin or indolebutyric acid) for 10 seconds; and 6) soaks with 10 mM sodium deoxycholate / 10 mM spermine plus a plant growth hormone (100 mg / L gibberellin or indolebutyric acid) for 10 seconds.

[0034] Figure 5 The anti-plant pathogen activity of sodium deoxycholate / polyamine liquid-liquid coacervates was tested on days 0, 1, 3, and 5 against water, corresponding concentrations of sodium deoxycholate, spermidine, spermine, sodium deoxycholate / spermidine, and sodium deoxycholate / spermine.

[0035] Figure 6Effects of sodium deoxycholate / polyamine solution-liquid coagulation on chilling stress in cowpea seeds. (a) Cowpea seed germination experiments were conducted on days 0, 2, and 4 with corresponding concentrations of commercial plant antifreeze, sodium deoxycholate / spermidine, sodium deoxycholate / spermine, and a blank control. (b) Germination rate and sprout length of cowpea seeds treated with different methods at 25°C for 4 days. Numbers 1-5 in each panel represent seeds treated with the following methods: 1) untreated; 2) frozen; 3) 6 mg / L commercial plant antifreeze; 4) 10 mM sodium deoxycholate / 10 mM spermidine; and 5) 10 mM sodium deoxycholate / 10 mM spermine. Cowpea seeds were frozen at -7°C for 7 days before germination. DETAILED DESCRIPTION

[0036] In order to further understand the present invention, the scheme provided by the present invention is described in detail below in combination with comparative examples and embodiments, but the present invention is not limited to these embodiments. Any other changes, replacements or combined simplifications made under the core idea of ​​the patent of the present invention are within the scope of protection of the patent of the present invention.

[0037] Example 1

[0038] Preparation and Characterization of Sodium Deoxycholate / Polyamine Liquid-Liquid Coacervates

[0039] First, NaDC and polyamine solutions of the same concentration (10 mM, 20 mM, 30 mM, 40 mM, 50 mM) were prepared respectively, and then mixed in a 1:1 volume ratio to obtain a liquid-liquid coacervate phase.

[0040] The polyamines are spermine and spermidine.

[0041] To determine the phase boundary of the sodium deoxycholate / spermidine (or spermine) mixed solution, 100 mM sodium deoxycholate was titrated into the spermidine or spermine solution, and the turbidity change was used to monitor the phase change of the system. Figure 1 As shown. Figure 1 It can be seen that with the addition of sodium deoxycholate, the turbidity of the sodium deoxycholate / spermidine (or spermine) mixed solution experienced a slow and rapid increase, and finally reached a maximum value and remained unchanged. Accordingly, from the turbidity change, it can be seen that the sodium deoxycholate / spermidine (or spermine) mixed solution experienced four phase zones: single phase, soluble complex, liquid-liquid coacervate phase and precipitation.

[0042] Figure 2(a) Chemical structures of sodium deoxycholate, spermidine, and spermine. (b) Cryo-transmission electron microscopy image of micelles in a 20 mM sodium deoxycholate solution. (c) Optical microscopy and (d) cryo-scanning electron microscopy images of coacervate droplets in a 20 mM sodium deoxycholate / 20 mM spermidine or spermine mixed solution, along with magnified images of their nanoscale network microstructure.

[0043] Depend on Figure 2 It can be seen that the assembly structure of 20mM sodium deoxycholate is a micelle structure ( Figure 2 b), and when mixed with 20 mM spermidine or spermine, a liquid-liquid condensate phase can be formed, and condensate phase droplets can be observed under an optical microscope ( Figure 2 c) By Figure 2 d It can be seen that the interior of the condensed phase droplets presents a network-like micro-nano structure, which lays the foundation for the efficient encapsulation of seed protectants (such as plant growth regulators) in the liquid-liquid condensed phase.

[0044] Example 2

[0045] Application of sodium deoxycholate / polyamine liquid-liquid coacervate as seed coating agent

[0046] After soaking wheat or cowpea seeds in sodium deoxycholate / polyamine liquid coacervate, a thin film can be formed on the surface of the seed coat. Figure 3 As shown, a scanning electron microscope image of the cross section of the coating agent shows that the liquid-liquid coacervate coating agent of the present invention forms a thin layer on the surface of the cowpea seeds with good film-forming properties, and the thickness of the thin layer is about 3 to 8 μm. Current hydrogel seed coatings also use a three-dimensional polymer network structure to achieve high loading rate and film-forming properties, but the problem is that the high viscosity may cause the coating to be too thick, thereby inhibiting seed respiration and germination. However, the coating layer formed on the seed surface by the liquid-liquid coacervate of the present application is only a few microns thick, which has no effect on seed respiration and germination, and the coating effect is better.

[0047] Example 3

[0048] Application of sodium deoxycholate / polyamine liquid-liquid coacervate phase encapsulating plant growth regulators to promote seed germination and growth

[0049] The liquid-liquid coacervate of the present invention can efficiently encapsulate seed protective agents, giving the seed coating agent additional functions. For example, treating seeds with a liquid-liquid coacervate of sodium deoxycholate / spermidine (spermine) encapsulated with a plant growth regulator (gibberellic acid or indolebutyric acid) can promote seed germination and growth and shorten seed treatment time. Figure 4 As shown, the germination and growth of wheat and cowpea seeds after soaking in water, commercial adjuvant and gibberellin for 4 hours on the 4th day were compared ( Figure 4(a) Wheat and cowpea seeds were treated with sodium deoxycholate / polyamine coacervate containing gibberellins and sodium deoxycholate / polyamine coacervate containing indolebutyric acid, respectively. The growth of seeds treated for only 10 seconds was significantly better than that of the above four control groups ( Figure 4 Groups 5 and 6 in a). Figure 4 As shown in Figures a and c, the germination rate of wheat increased significantly by ~10%, and the length of seedling sprouts increased by ~14%. The germination rate of cowpea increased by ~7%, and the length of sprouts increased by ~85%. This indicates that the sodium deoxycholate / polyamine liquid-liquid coacervate, as a carrier of growth hormone, can retain more growth hormone on the seed coat surface, thereby promoting seed germination and growth. Furthermore, compared to prolonged soaking, the liquid-liquid coacervate coating material of the present invention can shorten seed processing time and improve seed coating efficiency.

[0050] Example 4

[0051] Application of sodium deoxycholate / polyamine liquid-liquid coacervates against plant pathogens

[0052] The agar dilution method was used to study the antifungal effect of sodium deoxycholate / polyamine on the mycelial growth of Botrytis cinerea (the pathogen can be transmitted through various routes, including seed transmission. When some diseased seeds are planted, the pathogen will spread to the entire plant as the seeds grow). Each test substance was added to the PDA (potato dextrose agar) medium at a fixed concentration, and then 20 mL of these solutions were poured into a sterile culture dish (90 mm in diameter). The inoculum disk (10 mm in diameter) was removed from the side of each PDA plate that had been cultured for 7 days using a fixed diameter pipette tip. The center of the disk with mycelium was then placed upside down on a new culture dish cultured at 25°C. The experimental results are shown in the figure. Figure 5 As shown by Figure 5 It is clear that on day 5, the colonies in the blank group almost covered the entire PDA plate, and the colony growth rate in the high-concentration sodium deoxycholate and polyamine group far exceeded that in the low-concentration sodium deoxycholate / polyamine group. This shows that the mixture of sodium deoxycholate and polyamines has a very significant inhibitory effect on the plant pathogen Botrytis cinerea.

[0053] Example 5

[0054] Application of sodium deoxycholate / polyamine liquid-liquid coacervate as a coating agent to improve seed freezing resistance.

[0055] This example uses cowpea seeds to test the effect of sodium deoxycholate / polyamine liquid-liquid coacervate as a seed coating material on the relief of seeds under low temperature stress. Uniform cowpea seeds were selected for the experiment and briefly soaked in sodium deoxycholate / polyamine solution. Seeds pre-soaked three times with water and commercial plant antifreeze were used as controls. At the same time, seeds not soaked in any solution were used as blank controls. All experimental groups were treated with low-temperature freezing (-7°C, 7 days). The experimental results show that (such as Figure 6 Four days after sowing, low temperatures significantly reduced the germination rate and sprout length of untreated cowpea seeds. In contrast, cowpea seeds treated with the sodium deoxycholate / polyamine liquid-liquid coacervate significantly improved germination and growth quality, with an average germination rate 50% higher than the untreated frozen group, and sprout length increased by 2-3 times.

[0056] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A composition for preparing a coating agent, characterized in that: include: Sodium deoxycholate, polyamines, and water.

2. The composition according to claim 1, characterized in that The polyamine is selected from divalent, trivalent and higher polyamines; for example, at least one of spermine, spermidine, diethylenetriamine, 1,3-diaminopropane, 1,5-diaminopentane, 1,7-diaminoheptane and 1,9-diaminononane.

3. The composition according to claim 1 or 2, characterized in that The molar ratio of sodium deoxycholate to polyamine is 1:0.8 to 1:

13.

4. The composition according to any one of claims 1 to 3, characterized in that The amount of water used is such that the concentration of sodium deoxycholate is 0.5-100 mM.

5. The composition according to any one of claims 1 to 4, characterized in that The composition also includes seed protectants, such as plant growth regulators, fungicides, insecticides and biological agents; Preferably, the composition is prepared by mixing aqueous solutions of sodium deoxycholate and polyamines.

6. Use of the composition according to any one of claims 1 to 5 in the preparation of a seed coating agent.

7. A method for preparing a seed coating agent using the composition according to any one of claims 1 to 5, characterized in that: include: Aqueous solutions of sodium deoxycholate and polyamine are prepared separately and then mixed to obtain a liquid-liquid coacervate phase.

8. A method for preparing coated seeds using the composition according to any one of claims 1 to 5, characterized in that: include: Aqueous solutions of sodium deoxycholate and polyamine are prepared separately and then mixed to obtain a liquid-liquid coacervate phase; The seeds are soaked in the liquid-liquid coagulation phase and then taken out.

9. The method according to claim 8, characterized in that The operation of obtaining the liquid-liquid condensed phase or soaking is carried out at 0 to 50°C; Preferably, the molar ratio of sodium deoxycholate to polyamine is 1:0.8 to 1:13; Preferably, the concentrations of the aqueous solutions of sodium deoxycholate and polyamine are the same or different and are independently 0.5 to 100 mM; Preferably, the soaking time is more than 5 seconds; Preferably, the seeds are any plant seeds existing in nature.

10. Coated seeds prepared by the method of claim 8 or 9.

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