Dopamine nanoparticles for relieving plant salt stress and preparation method thereof

Abstract

The invention belongs to the technical field of agricultural nanoparticle preparations, and relates to a dopamine nanoparticle for relieving plant salt stress and a preparation method thereof. And adding the double-ligand chelated dopamine solution into the lignin-based nano-particle suspension, and stirring to obtain the lignin-based nano-particle suspension. According to the invention, metal ions are adopted as a connecting bridge and are respectively chelated with dopamine and ethylenediamine tetraacetic acid salt, so that double-ligand chelated dopamine is obtained, and the self-polymerization behavior of dopamine is inhibited. The invention also provides a method for loading dopamine by using lignin-based nanoparticles. The self-polymerization of the dopamine is further inhibited; the adsorption of the soil on the dopamine is reduced, and the utilization rate of the dopamine is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural nanoparticle preparations and relates to dopamine nanoparticles for alleviating plant salt stress and a preparation method thereof. Background Art

[0002] In agricultural planting worldwide, the area and degree of soil salinization are increasing year by year, seriously threatening food security and the ecological environment. In recent years, the application of exogenous growth regulators such as dopamine, brassinolide and strigolactone to improve the salt stress tolerance of plants has received widespread attention. Compared with brassinolide and strigolactone, dopamine is low in price and easy to expand synthetic production. However, due to its active chemical properties, dopamine is very likely to undergo irreversible self-polymerization during use to form polydopamine, which reduces the utilization rate of dopamine by plants. Therefore, delaying the self-polymerization of dopamine and applying it to alleviate plant salt stress has become an urgent problem to be solved. At present, there is no report on improving its utilization rate by inhibiting the self-polymerization of dopamine. Summary of the invention

[0003] The present invention utilizes the chelation of metal ions to inhibit the self-aggregation of dopamine; at the same time, in order to reduce the adsorption of dopamine by soil, lignin-based nanoparticles loaded with chelated dopamine are constructed to improve the delivery efficiency of dopamine. The dopamine nanoparticles prepared by the present invention have a simple preparation method and can be used to improve the salt tolerance of plants, which is of great significance for the comprehensive transformation and utilization of saline-alkali land in my country.

[0004] In order to achieve the above object, the present invention is implemented by adopting the following technical solutions: The invention provides a method for preparing a chelate for inhibiting dopamine self-polymerization. The method comprises mixing a metal ion solution and an ethylenediaminetetraacetate solution evenly, and then adding a dopamine solution to obtain a double-ligand chelated dopamine solution.

[0005] Preferably, the metal ion is Al 3+ , Fe 3+ , Fe 2+ Mg 2+ 、Zn 2+ , Mn 2+ , Cu 2+ Any one of the above, wherein the ethylenediaminetetraacetate salt is any one or more of ethylenediaminetetraacetic acid disodium, ethylenediaminetetraacetic acid tetrasodium, ethylenediaminetetraacetic acid dipotassium, ethylenediaminetetraacetic acid sodium iron, ethylenediaminetetraacetic acid tripotassium salt, and ethylenediaminetetraacetic acid disodium zinc; the molar ratio of metal ion: ethylenediaminetetraacetic acid salt: dopamine is 1: (0.1-5): (0.1-5), and preferably the molar ratio of metal ion: ethylenediaminetetraacetic acid salt: dopamine is 1: (0.1-1): (0.1-2).

[0006] The present invention also provides a method for preparing dopamine nanoparticles for alleviating plant salt stress, which comprises adding the above-prepared dual-ligand chelated dopamine solution to a lignin-based nanoparticle suspension under stirring, and continuing to stir to obtain the dopamine nanoparticles; the steps for preparing the lignin-based nanoparticle suspension are as follows: (1) The cationic component is dissolved in an organic solvent and stirred evenly as the oil phase, and deionized water is added under stirring to form an oil-in-water emulsion A.

[0007] (2) The anionic component including lignin sulfonate is dissolved in deionized water to obtain solution B.

[0008] (3) Add emulsion A to solution B under stirring and mix well to obtain a lignin-based nanoparticle suspension.

[0009] Preferably, the mass ratio of the dual-ligand chelated dopamine solution to the lignin-based nanoparticle suspension is 1:(0.1-20).

[0010] Preferably, in step (1), the cationic component is a primary amine salt, a secondary amine salt, a tertiary amine salt or a quaternary ammonium salt, and the mass ratio of the cationic component to the organic solvent is 1:(2-40). Among them, the primary amine salt is preferably dodecylamine hydrochloride or octadecylamine hydrochloride; the secondary amine salt is preferably dioctadecylamine hydrochloride; the tertiary amine salt is preferably N,N-dimethyloctadecylamine hydrochloride; the quaternary ammonium salt is preferably dodecyldimethylbenzylammonium chloride, tetradecyldimethylbenzylammonium chloride, octadecyldimethylbenzylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride or octadecyltrimethylammonium chloride. The organic solvent is any one of cyclohexanone, N,N-dimethylformamide, ethanol, methanol, dichloromethane and xylene. The mass ratio of the oil phase to deionized water is 1:1-30.

[0011] Preferably, the anion component of step (2) can be lignin sulfonate alone, or lignin sulfonate can be used in combination with any one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and acrylic acid-sodium styrene sulfonate copolymer; the lignin sulfonate is preferably sodium lignin sulfonate or calcium lignin sulfonate.

[0012] The present invention utilizes the chelation effect of metal ions and hydroxyl groups, uses metal ions as connecting bridges, and chelates with dopamine and ethylenediaminetetraacetate respectively, and obtains the biligand chelated dopamine, which inhibits the self-polymerization of dopamine. Subsequently, the cationic component is emulsified and dispersed in the aqueous phase using the water-in-oil emulsion as a template to form a cationic water-in-oil emulsion; it is added to the aqueous phase containing the anionic component, and spherical particles are formed by the electrostatic force between the anions and cations. Subsequently, the biligand chelated dopamine is added to the system, and the electrostatic adsorption effect of the chelated dopamine and the lignin-based particles is utilized to obtain the lignin-based nanoparticles loaded with dopamine. The formation of particles does not require the input of energy (high-speed shearing, ultrasound, etc.), and particles with controllable particle size can be obtained only by relying on the spontaneous emulsification ability of the amphiphilic molecules in the system. This feature is conducive to reducing the investment in equipment required in industrial production.

[0013] Compared with the prior art, the advantages and positive effects of the present invention are: 1. The present invention uses metal ions as connecting bridges to chelate with dopamine and ethylenediaminetetraacetate respectively to obtain double-ligand chelated dopamine, thereby inhibiting the self-aggregation behavior of dopamine.

[0014] 2. The present invention also proposes to use lignin-based nanoparticles to load dopamine, which further inhibits the self-aggregation of dopamine, reduces the adsorption of dopamine by the soil, and improves the utilization rate of dopamine. Moreover, the lignin-based carrier is easily degraded in the environment and will not cause new environmental pollution.

[0015] 3. In the process proposed by the present invention, the formation of particles does not require the input of additional high energy (high-speed shearing, ultrasound, etc.). Microcapsule particles with controllable particle size can be obtained only by relying on the spontaneous emulsification ability of the amphiphilic molecules in the system and the electrostatic force between anions and cations. This feature is conducive to reducing the investment in equipment required in industrial production and is suitable for large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The transmission electron microscope image of the nanoparticles obtained in the present invention.

[0017] Figure 2 This is the infrared spectrum of dopamine and dual-ligand chelated dopamine. DETAILED DESCRIPTION

[0018] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described below in conjunction with specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0019] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein. Therefore, the present invention is not limited to the specific embodiments of the following disclosure.

[0020] Example 1 (1) Weigh 0.3 g of disodium ethylenediaminetetraacetate and 0.075 g of zinc sulfate heptahydrate and dissolve them in 10 mL of deionized water, then mix the two aqueous solutions under magnetic stirring at 400 rpm to obtain an ethylenediaminetetraacetic acid / zinc solution. Then weigh 0.08 g of dopamine hydrochloride (CAS No.: 62-31-7) and dissolve it in 10 mL of deionized water, then add it to the ethylenediaminetetraacetic acid / zinc solution to prepare a dual-ligand chelated dopamine solution.

[0021] Take appropriate amounts of dopamine and dual-ligand chelated dopamine (when testing, freeze-dry the dual-ligand chelated dopamine solution in step (1) at -60°C for 24 hours to obtain a solid) and perform infrared characterization respectively, such as Figure 2 As shown, in the spectrum of dopamine, 3340 cm -1 is the stretching vibration peak of phenolic hydroxyl group, 3033 cm -1 is the stretching vibration peak of NH, 1506 cm -1 The peaks of benzene ring and phenolic hydroxyl group appear in the spectrum of dopamine with double ligand chelate, but the intensity is significantly reduced, which indicates that zinc combines with phenolic hydroxyl group of dopamine to form a coordination bond, thus forming dopamine with double ligand chelate.

[0022] (2) Dissolve 0.5 g of octadecyl dimethyl benzyl ammonium chloride in 5 mL of dichloromethane as the oil phase, and add 20 mL of deionized water to the oil phase under magnetic stirring at 400 rpm to form an oil-in-water emulsion. Dissolve 0.5 g of sodium lignin sulfonate in 40 mL of deionized water to form an aqueous phase, and slowly add the above-mentioned oil-in-water emulsion to the sodium lignin sulfonate aqueous phase, and continue to stir at 400 rpm for more than 5 minutes to obtain a suspension containing lignin-based nanoparticles. Mix 10 mL of the lignin-based nanoparticle suspension with 10 mL of the dual ligand chelated dopamine solution, and continue to stir at 400 rpm for more than 10 minutes to prepare a suspension containing dopamine nanoparticles.

[0023] Transmission electron microscopy of dopamine nanoparticles (the suspension can be tested by drying naturally). Figure 1 As shown, the particle shape is spherical. After testing, the average particle size of the particles is 245nm, and the dopamine loading rate is 19.85%.

[0024] Example 2 The present embodiment is consistent with the embodiment 1 unless otherwise specified.

[0025] 0.35 g of disodium ethylenediaminetetraacetic acid and 0.17 g of ferric chloride hexahydrate were weighed and dissolved in 15 mL of deionized water, and then the two aqueous solutions were mixed under magnetic stirring at 400 rpm to obtain an ethylenediaminetetraacetic acid / iron solution. Subsequently, 0.15 g of dopamine hydrochloride was weighed and dissolved in 15 mL of deionized water and added to the ethylenediaminetetraacetic acid / iron solution to prepare a dual-ligand chelated dopamine.

[0026] 1 g of dodecyl dimethyl benzyl ammonium chloride was dissolved in 10 mL of cyclohexanone as the oil phase, and 50 mL of deionized water was added to the oil phase under magnetic stirring at 400 rpm to form an oil-in-water emulsion. 0.45 g of sodium lignin sulfonate and 0.05 g of sodium dodecylbenzene sulfonate were dissolved in 40 mL of deionized water to form an aqueous phase, and the above-mentioned oil-in-water emulsion was slowly added dropwise to the sodium lignin sulfonate aqueous phase and stirred to prepare lignin-based nanoparticles. 10 mL of lignin-based nanoparticle solution was mixed with 10 mL of dual ligand chelated dopamine solution and stirred to prepare a suspension containing dopamine nanoparticles.

[0027] After testing, the average particle size of the particles was 204nm and the dopamine loading rate was 23.01%.

[0028] 1. Soil adsorption test Sample preparation: Sample 1: 40 mL of 5 mmol / L dopamine aqueous solution.

[0029] Sample 2: The dual-ligand chelated dopamine solution obtained in step (1) of Example 1 was added to deionized water and fixed to 40 mL, and mixed evenly. The effective molar amount of dopamine hydrochloride in Sample 2 was the same as that in Sample 1.

[0030] Sample 3: Take the dopamine nanoparticle suspension obtained in step (2) of Example 1, add it to deionized water and make the volume to 40 mL, mix well, so that the effective molar amount of dopamine hydrochloride in Sample 3 is the same as that in Sample 1.

[0031] Take soil samples (taken from the experimental field of Shandong Agricultural University, no special requirements), pass through a 100-mesh sieve, and then weigh 10g of soil samples as a group. Weigh three groups in total, record them as a1, a2, and a3, and pour sample one into soil sample a1. Stir and mix at 2800 rpm for 15 minutes, and then centrifuge at 5000 rpm for 5 minutes. Take 5mL of the supernatant after centrifugation and pass it through a 0.22 μm organic membrane (Jiangsu Green Alliance Scientific Instrument Co., Ltd., needle filter 13, organic nylon 66), and then detect it using a UV-visible spectrophotometer. Pour sample two into soil sample a2, and sample three into soil sample a3 and treat them using the same steps, and then detect them using a UV-visible spectrophotometer.

[0032] Each of the above treatment groups was tested five times in parallel and then detected using a UV-visible spectrophotometer.

[0033] After testing, the amount of dopamine adsorbed by the soil in sample 1 reached 79.72±2.74%, the amount of dopamine adsorbed by the soil in sample 2 reached 48.96±2.19%, and the amount of dopamine adsorbed by the soil in dopamine nanoparticles in sample 3 was 33.65±0.97%. Therefore, the method proposed in the present invention can significantly reduce the adsorption of dopamine by the soil, thereby improving the utilization rate of dopamine absorbed by plants.

[0034] 2. Pear seedling experiment Select pear seedlings after 70 days of cultivation, remove those that are too short or too tall, and those with abnormal growth (such as yellow leaves), and then divide them into four large groups, each of which has three small parallel groups, each with 10 plants. The four large groups are recorded as P1-P4, and the following reagents are used for in-situ irrigation: P1: deionized water.

[0035] P2: 100mmol / L NaCl aqueous solution.

[0036] P3: A mixed aqueous solution of 100 mmol / L NaCl and 50 μmol / L dopamine.

[0037] P4: a mixture of 100 mmol / L NaCl and 50 μmol / L dopamine nanoparticles (Example 1) in water.

[0038] Watering was performed every other day, with a watering volume of 500 mL per group; each seedling was watered 20 times, and the plant height and root length of the 40-day seedlings were recorded. The root length was measured by Wanshen LA-S series image analyzer (Wanshen Testing Technology Co., Ltd., Hangzhou, China). The results showed that the growth status of each treatment group in each large group was basically the same. For the convenience of comparison, the root length and plant height of all plants in each large group were measured and counted. The results are shown in Table 1 below.

[0039] Table 1 Effects of dopamine on root length, plant height and growth status of pear seedlings under salt stress 3. Tomato seedling experiment Tomato (Provence) seedlings were selected after 35 days of cultivation. The seedlings that were too short or too tall, as well as those with abnormal growth conditions (such as yellowing leaves) were removed. Then they were divided into four large groups. Each large group was set up with three small parallel groups, each with 10 plants. The four large groups were recorded as R1-R4, and the following reagents were used for in-situ irrigation: R1: Water.

[0040] R2: 100mmol / L NaCl aqueous solution.

[0041] R3: A mixed aqueous solution of 100 mmol / L NaCl and 50 μmol / L dopamine.

[0042] R4: a mixture of 100 mmol / L NaCl and 50 μmol / L dopamine nanoparticles (Example 2) in water.

[0043] Watering was performed every other day, with a watering volume of 500 mL per group; each seedling was watered 20 times, and the plant height and root length of the 40-day seedlings were recorded. The root length was measured by Wanshen LA-S series image analyzer (Wanshen Testing Technology Co., Ltd., Hangzhou, China). The results showed that the growth status of each treatment group in each large group was basically the same, and the statistical results are shown in Table 2 below.

[0044] Table 2 Effects of dopamine on root length, plant height and growth status of tomato seedlings under salt stress It can be seen from the above plant experiments that when the pear seedlings and tomato seedlings are subjected to sodium chloride salt stress, the growth state is seriously affected, the leaves turn yellow, the plants are short, and even die. Dopamine has a mitigating effect on the salt stress of plants, but when used alone, the effect is limited. The dopamine nanoparticles prepared by the present invention significantly improve the effect of relieving the salt stress of pear seedlings and tomato seedlings.

[0045] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a chelate for inhibiting dopamine self-aggregation, characterized in that: The metal ion solution and the ethylenediaminetetraacetate solution are mixed evenly, and then the dopamine solution is added to obtain a double ligand chelated dopamine solution.

2. The method for preparing a chelate for inhibiting dopamine self-aggregation according to claim 1, characterized in that: The metal ion is Al 3+ , Fe 3+ , Fe 2+ Mg 2+ 、Zn 2+ , Mn 2+ , Cu 2+ Any one of the above, wherein the EDTA salt is any one or more of EDTA disodium, EDTA tetrasodium, EDTA dipotassium, EDTA sodium iron, EDTA tripotassium, and EDTA disodium zinc; the molar ratio of metal ion: EDTA salt: dopamine is 1: (0.1-5): (0.1-5).

3. A method for preparing dopamine nanoparticles for alleviating plant salt stress, characterized in that: The dual-ligand chelated dopamine solution prepared in claim 1 or 2 is added to the lignin-based nanoparticle suspension under stirring, and the stirring is continued to obtain the lignin-based nanoparticle suspension; the steps for preparing the lignin-based nanoparticle suspension are as follows: (1) dissolving the cationic component in an organic solvent and stirring the mixture evenly as the oil phase, and adding deionized water under stirring to form an oil-in-water emulsion A; (2) dissolving an anionic component including lignin sulfonate in deionized water to obtain solution B; (3) Add emulsion A to solution B under stirring and mix well to obtain a lignin-based nanoparticle suspension.

4. The method for preparing dopamine nanoparticles for alleviating plant salt stress according to claim 3, characterized in that: The mass ratio of the dual-ligand chelated dopamine solution to the lignin-based nanoparticle suspension is 1:(0.1-20).

5. The method for preparing dopamine nanoparticles for alleviating plant salt stress according to claim 3, characterized in that: In the step (1), the cationic component is a primary amine salt, a secondary amine salt, a tertiary amine salt or a quaternary ammonium salt, and the mass ratio of the cationic component to the organic solvent is 1:(2-40).

6. The method for preparing dopamine nanoparticles for alleviating plant salt stress according to claim 3, characterized in that: The anion component in step (2) further comprises sodium dodecyl sulfate and / or sodium dodecylbenzene sulfonate.

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