Betaine-based surfactant composite sodium alginate pesticide nano-carrier and preparation method thereof

Abstract

This invention discloses a betaine-based surfactant-sodium alginate pesticide nanocarrier, its preparation method, and its application, relating to the field of pesticide adjuvant technology. The betaine-based surfactant-sodium alginate pesticide nanocarrier of this invention comprises the following self-assembled components: a surfactant and sodium alginate; the mass ratio of the surfactant to sodium alginate is 1:(0.1~1); the surfactant is a betaine-coupled long-chain aliphatic hydrocarbon cationic surfactant. This invention obtains the nanocarrier by combining a synthesized surfactant with natural high-molecular-weight sodium alginate through a self-assembly process. This composite system not only holds promise as a highly efficient pesticide nanocarrier, improving the absorption and translocation efficiency of pesticides from the root surface to the vascular system, but also, due to its specific chemical structure and biological activity, exhibits a positive promoting effect on plant seed germination and early growth.

Description

Technical Field

[0001] This invention relates to the field of pesticide adjuvant technology, and more specifically, to a betaine-based surfactant composite sodium alginate pesticide nanocarrier and its preparation method. Background Technology

[0002] As a crucial component of pesticide formulations, pesticide adjuvants primarily function to improve the solubility, stability, wetting and spreading properties, penetration, and targeted delivery of active ingredients, thereby significantly enhancing pesticide utilization efficiency and control efficacy. However, traditional pesticide adjuvants, especially some synthetic surfactants, have revealed problems such as environmental residues, biotoxicity, and potential ecological risks during long-term use, making it difficult to meet the growing demands of modern agriculture for green and sustainable development. Therefore, developing novel, environmentally friendly pesticide adjuvants that are highly efficient, low in toxicity, easily degradable, and multifunctional has become a research hotspot and important direction in the field of pesticide formulation.

[0003] Quaternary ammonium salts (QASs), as cationic surfactants or solute promoters, are widely used in commercial products such as agrochemical auxiliaries, disinfectants, cosmetics, and pharmaceuticals. In crop protection, QASs offer excellent emulsification, dispersion, and adsorption properties to enhance pesticide efficacy. However, traditional single-chain quaternary ammonium salts often exhibit high biotoxicity and poor degradability. Betaine-type amphoteric surfactants, due to their unique molecular structure, maintain good compatibility and low irritation under different pH conditions and typically possess superior biodegradability. Combining the mild properties of betaine-type surfactants with the efficient penetration and adsorption capabilities of quaternary ammonium cations holds promise for developing novel surfactants with more balanced performance. However, simple small-molecule surfactants, when used as pesticide carriers, still suffer from drawbacks such as short duration of action, easy loss, and limited loading and controlled-release capabilities for active ingredients. On the other hand, natural polymers such as sodium alginate (SA), due to their wide availability, renewability, excellent biocompatibility, and biodegradability, have been extensively studied as drug delivery carriers. However, it is often not very efficient at loading hydrophobic pesticides, and its ability to penetrate plant epidermis and transmembrane transport is weak, which limits its direct application in efficient pesticide delivery systems. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a betaine-based surfactant-composite sodium alginate pesticide nanocarrier, its preparation method, and its application. This invention is prepared by combining a synthesized surfactant with natural high-molecular-weight sodium alginate via a self-assembly process. The surfactant provides excellent penetration and transmembrane transport capabilities, while sodium alginate forms a stable nanocarrier structure, achieving protection and controlled release of the active ingredient. This composite system not only holds promise as a highly efficient pesticide nanocarrier, improving the absorption and transport efficiency of pesticides from the root surface to the vascular system, but also, due to its specific chemical structure and biological activity, positively promotes plant seed germination and early growth. While solving the environmental risks of traditional adjuvants and the efficiency and functional limitations of carrier systems, this invention provides an innovative technical solution for developing next-generation high-performance green pesticide formulations.

[0005] One objective of this invention is to provide a betaine-based surfactant composite sodium alginate pesticide nanocarrier.

[0006] The betaine-based surfactant composite sodium alginate pesticide nanocarrier of the present invention comprises the following self-assembled components:

[0007] Surfactants and sodium alginate (SA); The mass ratio of the surfactant to sodium alginate is 1:(0.1~1); The surfactant is a betaine-coupled long-chain aliphatic hydrocarbon-based cationic surfactant.

[0008] Betaine is an important metabolite in plants, with its functional group being a quaternary ammonium salt. It enhances plant resistance to various environmental stresses through osmotic regulation and cell protection, playing a crucial role in improving plant stress resistance. On the other hand, higher fatty alcohols (HFAs) are emerging as multifunctional bioactive compounds, capable of enhancing plants' ability to resist various abiotic and biotic stresses. For example, lauryl alcohol can significantly improve plant tolerance to abiotic stresses by regulating stomatal closure to conserve water and promoting the synthesis and deposition of epidermal waxes on leaves. Therefore, this invention designs and prepares novel adjuvants using betaine and naturally derived esters as the backbone. This not only improves pesticide application performance but also enhances plant resistance and avoids the residual risks arising from the degradation of adjuvants into chemical fragments through ester hydrolysis in the field or within the plant.

[0009] In a preferred embodiment of the present invention: The mass ratio of the surfactant to sodium alginate is 1:(0.4~0.5).

[0010] In a preferred embodiment of the present invention: The betaine coupled with a long-chain aliphatic hydrocarbon-based cationic surfactant , , At least one of them, where R is C 12 H 24 Or C 14 H 28 a is 5 or 6, and b is 4 or 6.

[0011] In a preferred embodiment of the present invention: The It is prepared by reacting raw materials including bromoalkane, betaine, and solvent; preferably, The molar ratio of the bromoalkane to betaine is (1~2):1, preferably (1.25~1.5):1; and / or, The ratio of the solvent to the total mass of bromoalkane and betaine is (1.5~5):1, preferably (2~3.5):1; and / or, The bromoalkane is 7-(bromomethyl)pentadecane; and / or, The solvent is acetonitrile; and / or, The reaction temperature is 70-120℃, preferably 80-90℃, and / or the reaction time is 4h-8h, preferably 5h-6h.

[0012] In a preferred embodiment of the present invention: The It is prepared by reacting raw materials including alkyl sulfonic acid, betaine, alkyl alcohol and solvent; preferably, The molar ratio of the alkyl alcohol, betaine, and alkyl sulfonic acid is 2:(0.5~2):2, preferably 2:(1~1.2):2; and / or, The ratio of the solvent to the total mass of the alkyl alcohol, betaine, and alkyl sulfonic acid is (1~4):1, preferably (2~3):1; and / or, The alkyl sulfonic acid is methane sulfonic acid; and / or, The alkyl alcohol is 7-tetradecanoic acid and / or 9-heptadecanoic acid; and / or, The solvent is acetonitrile; and / or, The reaction temperature is 120~140℃, preferably 130~135℃, and / or the reaction time is 4h-8h, preferably 5h-6h.

[0013] In a preferred embodiment of the present invention: The It is prepared by reacting raw materials including bromoalkane, betaine, and solvent; preferably, The molar ratio of the bromoalkane to betaine is (1~2):1, preferably (1~1.5):1; and / or, The ratio of the solvent to the total mass of bromoalkane and betaine is (1.5~5):1, preferably (2~3.5):1; and / or, The bromoalkane is 1,12-dibromododecane and / or 1,14-dibromotetradecane; and / or, The solvent is acetonitrile; and / or, The reaction temperature is 70-120℃, preferably 80-90℃, and / or the reaction time is 4h-8h, preferably 5h-6h.

[0014] The fourth objective of this invention is to provide a method for preparing a betaine-based surfactant composite sodium alginate pesticide nanocarrier as described in one objective of this invention.

[0015] The preparation method of the betaine-based surfactant composite sodium alginate pesticide nanocarrier of the present invention includes: An aqueous solution of sodium alginate was added dropwise to an aqueous solution of a surfactant, and the mixture was stirred to react, thus obtaining the pesticide nanocarrier.

[0016] In a preferred embodiment of the present invention: The concentration of the aqueous solution of sodium alginate is 0.1-0.6 mg / mL, preferably 0.3-0.4 mg / mL; and / or, The concentration of the aqueous solution of the surfactant is 0.1-0.5 mg / mL, preferably 0.15-0.4 mg / mL.

[0017] In a preferred embodiment of the present invention: The dropping rate is 0.2-1 mL / min, and / or the rotation speed is 300-800 rpm; and / or, The stirring reaction is carried out at a speed of 300-800 rpm and / or for a time of 10-50 min.

[0018] The following solutions can be adopted: (1) Prepare an aqueous solution of surfactant with a concentration of 0.1-0.5 mg / mL, sonicate for 10 minutes and set aside for use; (2) Prepare an aqueous solution of SA with a concentration of 0.1-0.6 mg / mL, and homogenize the aqueous solution in a high-speed homogenizer at 10000 rpm for 3 min to obtain a fully dissolved aqueous solution of SA for later use; (3) The aqueous solution of SA is slowly and evenly added to the aqueous solution of surfactant under magnetic stirring at 300-800 rpm. After the addition is completed, magnetic stirring is continued for 10-50 min to form a betaine-based surfactant composite sodium alginate pesticide nanocarrier.

[0019] This invention uses the zwitterionic framework of betaine and long-chain alkane structures as raw materials to synthesize betaine-coupled long-chain aliphatic hydrocarbon cationic surfactants of different chain lengths. The synthesized betaine-coupled long-chain aliphatic hydrocarbon cationic surfactants are then self-assembled with sodium alginate. Through electrostatic attraction and hydrophobic interactions between the surfactant carbon chains, stable nanoparticle pesticide nanocarriers with uniform size are formed. These pesticide nanocarriers significantly promote plant seed germination and early growth. Confocal microscopy observation confirms that they promote the absorption and translocation of active ingredients from the plant root surface to the vascular system, making them highly efficient pesticide nanocarriers. Furthermore, acute toxicity experiments in zebrafish show that these pesticide nanocarriers have low toxicity to aquatic animals, aligning with the development trend of green pesticides. The novel pesticide nanocarriers provided by this invention combine environmental friendliness and high functional efficiency, offering a reliable solution for developing new green pesticide formulations.

[0020] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships, such as A and / or B. Specifically, it can mean that A and B can be included at the same time, A can exist alone, or B can exist alone, and any of the above three situations can be met. Attached Figure Description

[0021] Figure 1 The above is the 1H NMR spectrum of the betaine coupled with a long-chain aliphatic hydrocarbon cationic surfactant prepared in Example 1 of this invention. Figure 1 middle 1 H NMR (600 MHz, Methanol- d 4) δ 4.19 (s, 2H), 3.67 (s, 2H), 3.38 (s, 9H), 1.72 – 1.68 (m, 1H), 1.29 (s, 24H), 0.91 – 0.90 (m, 6H); Figure 2 The carbon NMR spectrum of the betaine coupled with a long-chain aliphatic hydrocarbon cationic surfactant prepared in Example 1 of this invention; Figure 2 middle 13 C NMR (151 MHz, Methanol- d 4) δ 166.20, 67.79, 64.35, 54.70,34.59, 34.14, 30.77, 30.46, 29.98, 29.61, 29.30, 27.01; Figure 3 The 1H NMR spectrum of the betaine coupled with a long-chain aliphatic hydrocarbon cationic surfactant prepared in Example 2 of this invention; Figure 3 middle 1 H NMR (500 MHz, Methanol- d 4) δ 4.72 (t, J = 9.0 Hz, 1H), 4.41 (s, 2H), 3.35 (s, 9H), 2.86 (s, 3H), 1.75 - 1.69 (m, 4H), 1.40 - 1.28 (m, 18H), 0.89 (t, J = 5.4 Hz, 6H); Figure 4 The carbon NMR spectrum of the betaine coupled with a long-chain aliphatic hydrocarbon cationic surfactant prepared in Example 2 of this invention; Figure 4 middle 13 C NMR (125 MHz, Methanol- d 4) δ 162.61, 68.27, 56.42, 49.04,35.71, 28.59, 26.57, 24.19, 23.97, 19.97, 17.42, 8.84; Figure 5 The 1H NMR spectrum of the betaine coupled with a long-chain aliphatic hydrocarbon cationic surfactant prepared in Example 3 of this invention; Figure 5 middle 1 H NMR (500 MHz, Methanol- d 4) δ 4.74 – 4.66 (m, 1H), 4.37 (d, J =16.3 Hz, 2H), 3.33 (s, 9H), 2.87 (s, 3H), 1.73 - 1.66 (m, 4H), 1.46 - 1.18 (m, 24H), 0.89 - 0.84 (m, 6H); Figure 6 The carbon NMR spectrum of the betaine coupled with a long-chain aliphatic hydrocarbon cationic surfactant prepared in Example 3 of this invention; Figure 6 middle 13 C NMR (125 MHz, Methanol- d 4) δ 168.99, 73.32, 61.54, 54.27, 40.94, 34.00, 32.01, 29.66, 29.02, 25.22, 22.69, 14.05; Figure 7 The 1H NMR spectrum of the betaine coupled with a long-chain aliphatic hydrocarbon cationic surfactant prepared in Example 4 of this invention; Figure 7 middle 1 H NMR (600 MHz, Chloroform-d) δ 5.00 (s, 4H), 4.16 (t, J = 7.0Hz, 4H), 3.68 (s, 18H), 1.84 (p, J = 7.0 Hz, 4H), 1.64 (p, J = 6.7 Hz, 4H), 1.26 (s, 12H); Figure 8 The 1H NMR spectrum of the betaine coupled with a long-chain aliphatic hydrocarbon cationic surfactant prepared in Example 5 of this invention; Figure 8 middle 1 H NMR (600 MHz, Methanol- d 4) δ 4.42 (s, 4H), 4.27 (t, J = 6.7 Hz,4H), 3.36 (s, 18H), 1.85 (dt, J = 14.5, 6.8 Hz, 4H), 1.71 (p, J = 6.7 Hz, 4H),1.31 (s, 16H); Figure 9 This is a scanning electron microscope image of the pesticide nanocarrier prepared in Example 4 of the present invention. Figure 10 This is a scanning electron microscope image of the pesticide nanocarrier prepared in Example 5 of the present invention. Figure 11 The diagram shows the effect of the pesticide nanocarriers prepared in Examples 1-5 of this invention on cotton germination. Figure 12 The graph shows the effect of the pesticide nanocarriers prepared in Examples 1-5 of this invention on the fresh weight of cotton. Figure 13 The graph shows the effect of the pesticide nanocarriers prepared in Examples 1-5 of this invention on the dry weight of cotton roots. Figure 14 This is a diagram showing the effect of the pesticide nanocarrier prepared in Example 4 of the present invention on cotton root growth; Figure 15 Microscopic images of the pesticide nanocarrier prepared in Example 4 of this invention entering cotton root tip cells at different times. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0023] All raw materials used in the embodiments of this invention are commercially available products.

[0024]

Example 1

[0025]

[0026] Preparation of pesticide nanocarriers: The prepared 2-[(2-heptylnonyl)oxy]-N,N,N-trimethyl-2-oxoethane-1-ammonium bromide was dissolved in 1 mL of methanol solution, and then 49 mL of distilled water was added to prepare an aqueous solution of surfactant with a concentration of 0.20 mg / mL. The solution was then sonicated for 10 minutes before use.

[0027] Homogenize 10 mL of a 0.20 mg / mL SA aqueous solution in a high-speed homogenizer at 10,000 rpm for 3 min to obtain a fully dissolved SA aqueous solution for later use.

[0028] The above 10 mL SA aqueous solution was uniformly added dropwise at a rate of 0.5 mL / min to 50 mL surfactant aqueous solution under magnetic stirring at 500 rpm. After the addition was completed, magnetic stirring was continued for 30 min to form a betaine-based surfactant composite sodium alginate pesticide nanocarrier.

[0029]

Example 2

[0030]

[0031] Preparation of pesticide nanocarriers: The prepared trimethyl[2-oxo-2-(tetradecane-7-yloxy)ethyl]nitromethanesulfonate was dissolved in 1 mL of methanol solution, and then 49 mL of distilled water was added to prepare an aqueous solution of surfactant with a concentration of 0.20 mg / mL. The solution was then sonicated for 10 minutes before use.

[0032] Homogenize 10 mL of a 0.20 mg / mL SA aqueous solution in a high-speed homogenizer at 10,000 rpm for 3 min to obtain a fully dissolved SA aqueous solution for later use.

[0033] The above 10 mL SA aqueous solution was uniformly added dropwise at a rate of 0.5 mL / min to 50 mL surfactant aqueous solution under magnetic stirring at 500 rpm. After the addition was completed, magnetic stirring was continued for 30 min to form a betaine-based surfactant composite sodium alginate pesticide nanocarrier.

[0034]

Example 3

[0035]

[0036] Preparation of pesticide nanocarriers: The prepared 2-(heptadecane-9-oxy)-N,N,N-trimethyl-2-oxoethane-1-ammonium methanesulfonate was dissolved in 1 mL of methanol solution, and then 49 mL of distilled water was added to prepare an aqueous solution of surfactant with a concentration of 0.20 mg / mL. The solution was then sonicated for 10 minutes before use.

[0037] Homogenize 10 mL of a 0.20 mg / mL SA aqueous solution in a high-speed homogenizer at 10,000 rpm for 3 min to obtain a fully dissolved SA aqueous solution for later use.

[0038] The above 10 mL SA aqueous solution was uniformly added dropwise at a rate of 0.5 mL / min to 50 mL surfactant aqueous solution under magnetic stirring at 500 rpm. After the addition was completed, magnetic stirring was continued for 30 min to form a betaine-based surfactant composite sodium alginate pesticide nanocarrier.

[0039]

Example 4

[0040]

[0041] Preparation of pesticide nanocarriers: The prepared 1,12-bis(trimethylammonium acetoxy)dodecane dibromide was dissolved in 1 mL of methanol solution, and then 49 mL of distilled water was added to prepare an aqueous solution of surfactant with a concentration of 0.20 mg / mL. The solution was then sonicated for 10 minutes before use.

[0042] Homogenize 10 mL of a 0.40 mg / mL SA aqueous solution in a high-speed homogenizer at 10,000 rpm for 3 min to obtain a fully dissolved SA aqueous solution for later use.

[0043] The above 10 mL SA aqueous solution was uniformly added dropwise at a rate of 0.5 mL / min to 50 mL surfactant aqueous solution under magnetic stirring at 500 rpm. After the addition was completed, magnetic stirring was continued for 30 min to form a betaine-based surfactant composite sodium alginate pesticide nanocarrier.

[0044]

Example 5

[0045]

[0046] Preparation of pesticide nanocarriers: The prepared 1,14-bis(trimethylammonium acetoxy)tetradecane dibromide was dissolved in 1 mL of methanol solution, and then 49 mL of distilled water was added to prepare an aqueous solution of surfactant with a concentration of 0.20 mg / mL. The solution was then sonicated for 10 minutes before use.

[0047] Homogenize 10 mL of an aqueous solution of 0.40 mg / mL SA in a high-speed homogenizer at 10,000 rpm for 3 min to obtain a fully dissolved aqueous solution of SA for later use.

[0048] The above 10 mL SA aqueous solution was slowly and uniformly added dropwise to 50 mL surfactant aqueous solution at a rate of 0.5 mL / min under magnetic stirring at 500 rpm. After the addition was completed, magnetic stirring was continued for 30 min to form a betaine-based surfactant composite sodium alginate pesticide nanocarrier.

[0049] The pesticide nanocarriers obtained in the above examples were subjected to acute toxicity tests in zebrafish according to the methods in GB / T 13267-1991. The specific test procedures are as follows: 1) Acute toxicity test of zebrafish (1) Selection and domestication of zebrafish Select healthy adult zebrafish (6-7 months old), with uniform body length (≤7cm), and free from disease or external injuries. Before the experiment, acclimate them in a constant temperature aquarium (28.5±0.5℃) for 7 days, using a 14-hour light / 10-hour dark cycle, pH 7.0-7.5, dissolved oxygen ≥4mg / L, and feed them twice a day at fixed times and in fixed quantities.

[0050] (2) Preparation of test solvent The pesticide adjuvant was serially diluted with deionized water, and more than 5 concentration groups were set up (geometric interval ≤ 2.2), and a blank control group (normal feeding water) was set up.

[0051] (3) Setting the exposure concentration gradient In terms of experimental design, a preliminary experiment was conducted, preparing three concentrations of drug solution: 20 mg / L, 10 mg / L, and 1 mg / L. Domesticated zebrafish were then placed in each solution to determine the maximum mortality concentration range. Based on the preliminary experiment results, the formal experiment included at least five different concentrations of the test substance and a control group. Each group was repeated at least three times, with 10 fish placed in each group. A semi-static method was used, and the experimental drug solution was changed every 24 hours to ensure the accuracy and reliability of the experimental data.

[0052] (4) Median lethal concentration (LC50) 50 )calculate Median lethal concentration (LC50) 50 The concentration-mortality rate (LC) can be calculated using either graphical or statistical methods. Graphical methods rely on the concentration-mortality curve for visual determination. Statistical methods use the probability unit method, converting the mortality rate to probability units and the concentration to a logarithm. A linear regression equation is then constructed, and the concentration corresponding to a probability unit of 5 is calculated as LC. 50 .

[0053] Median lethal concentration (LC50) 50 The calculation formula is:

[0054] in, Logarithmic concentration of the highest dose group Logarithm of the ratio between adjacent dose groups : The sum of mortality rates for each group.

[0055] The results are shown in Table 1 below. The LC-100 of the pesticide nanocarrier prepared in Example 1 50 =13.994; LC-13.994 of the pesticide nanocarrier prepared in Example 250 =8.641; LC-100 of the pesticide nanocarrier prepared in Example 3 50 =5.480; LC-100 of the pesticide nanocarrier prepared in Example 4 50 =17.055; LC-17.055 of the pesticide nanocarrier prepared in Example 5 50 =15.155. Referring to Part 28 of GB 30000.28-2013 Chemical Classification and Labelling Specification, the pesticide nanocarriers prepared in the embodiments of the present invention have low toxicity, and the pesticide nanocarriers in Examples 1, 4 and 5 have even lower toxicity, making them excellent materials for the development of green pesticide adjuvants.

[0056] Table 1

[0057] The pesticide nanocarriers prepared in the above embodiments were subjected to growth-promoting tests, and the specific test methods are as follows: A pot experiment was conducted to evaluate the effects of pesticide adjuvants on cotton growth. A completely randomized controlled design was used. The test material was cotton seed "Tahe 2". Five concentration gradients of pesticide nanocarriers (0, 25, 50, 100, and 200 mg / L) were set up for a total of 5 treatments. The 0 mg / L water-soaked control group (CK) was used. After surface sterilization with 75% ethanol solution, the seeds were soaked in the corresponding concentration of pesticide adjuvant solution at a liquid-to-seed ratio of 3:1 for 12 h (at 25℃ in the dark). Then, they were sown in PVC pots (20cm × 15cm) with a sterilized substrate (garden soil:vermiculite = 3:1, pH 6.8). The experiment was conducted in an artificial climate chamber with a light intensity of 600 μmol·m². -2 ·s -1 (Photoperiod 14h / d), day / night temperature 25 / 20℃, relative humidity 65%, uniform irrigation (maintaining substrate moisture content 60%±5%). 20 replicates per group, with each experiment repeated three times to ensure experimental reliability.

[0058] At 30 days, intact plants were harvested, and their fresh weight, dry weight, and root dry weight were measured. Fresh weight measurement: Plant material was quickly cut and placed in a container (kraft paper bag) of known weight. The fresh weight was then measured using an analytical balance indoors. Dry weight measurement: The fresh weight sample was placed in an oven, first blanched at 105℃ for 10-15 minutes, then the oven temperature was adjusted to 80℃ and the sample was dried to constant weight. After cooling to room temperature, the sample was weighed.

[0059] Test results are as follows Figure 11-14As shown, the results revealed a clear concentration-dependent response. Within the optimal concentration range, treatment with pesticide nanocarriers significantly promoted seedling growth. Plants treated at effective concentrations showed significant increases in biomass indicators such as fresh weight and root dry weight, far exceeding the untreated control group. This indicates that appropriate application of pesticide nanocarriers can simultaneously promote stem, leaf, and root development, bringing significant advantages to crop growth. However, when the concentration exceeded a certain threshold, an inhibitory effect on plant growth was observed, manifested as a decrease in biomass accumulation. This biphasic response characteristic—low concentration promoting growth and high concentration inhibiting growth—is consistent with a typical agonistic effect pattern. These findings provide crucial evidence for determining the optimal application dosage of pesticide nanocarriers.

[0060] The pesticide nanocarrier prepared in Example 4 above was subjected to an internal absorption test. The specific test method is as follows: FITC-labeled sodium alginate method: 1 g of sodium alginate was dissolved in 100 mL of MES buffer and magnetically stirred until completely dissolved. Excess EDC was added to the solution, and the mixture was activated at room temperature in the dark for 2 hours. Excess ethylenediamine was added dropwise, and the reaction was continued at room temperature in the dark for 12 hours. The mixture was then dialyzed and freeze-dried to obtain a white sodium alginate-ethylenediamine copolymer solid. This solid was dissolved in a carbonate buffer solution with a pH of 8.5-9.0. An alkaline environment favors the reaction of FITC with amino groups; excess FITC was dissolved in a small amount of anhydrous DMSO. The FITC DMSO solution was slowly added dropwise to the sodium alginate-ethylenediamine solution under vigorous stirring, and the reaction was carried out at room temperature in the dark for 12 hours. The mixture was then dialyzed and freeze-dried to obtain FITC-labeled sodium alginate.

[0061] Cotton hydroponics and laser confocal microscopy experimental methods: The cotton variety "Tahe No. 2" was used. Uniformly sized cotton seeds were sterilized and soaked for 24 hours to promote germination. Vigorous and uniformly developed seedlings were then transplanted into black hydroponic boxes containing 200 ml of Hoagland's nutrient solution. After 5 days of cultivation in a constant temperature and humidity chamber (28℃, 14 / 10-hour diurnal cycle), the root length of all seedlings exceeded 5 cm. During the exposure period, the roots of the seedlings were transplanted into a nutrient solution labeled with a pesticide adjuvant (25 mg / L) and fluorescent isothiocyanate. Samples were collected at 1 hour, 5 hours, and 10 hours, and root tip tissue sections were observed using a laser confocal microscope.

[0062] The results are as follows Figure 15As shown, in the initial exposure phase (1 hour), it mainly accumulates near the cell membranes of root epidermal cells, with a shallow initial penetration. As time extends to 5 hours, it is able to penetrate the cortical tissue and successfully reach the xylem. By 10 hours, it has further accumulated in the area surrounding the vascular bundles. This demonstrates that the pesticide nanocarrier of this invention possesses excellent systemic transport capabilities. Its absorption and transport in cotton roots is a time-dependent dynamic process, primarily entering and accumulating in the vascular bundle system rapidly through the intercellular pathway, thus enabling it to carry pesticide active ingredients for long-distance transport within the plant.

Claims

1. A betaine-based surfactant composite sodium alginate pesticide nanocarrier, characterized in that... The pesticide nanocarrier comprises the following self-assembled components: Surfactants and sodium alginate; The mass ratio of the surfactant to sodium alginate is 1:(0.1~1); The surfactant is a betaine-coupled long-chain aliphatic hydrocarbon-based cationic surfactant.

2. The pesticide nanocarrier according to claim 1, characterized in that: The mass ratio of the surfactant to sodium alginate is 1:(0.4~0.5); and / or, The betaine coupled with a long-chain aliphatic hydrocarbon-based cationic surfactant , , At least one of them, where R is C 12 H 24 Or C 14 H 28 a is 5 or 6, and b is 4 or 6.

3. The pesticide nanocarrier according to claim 2, characterized in that: The It is prepared by reacting raw materials including bromoalkane, betaine, and solvent; preferably, The molar ratio of the bromoalkane to betaine is (1~2):1, preferably (1.25~1.5):1; and / or, The ratio of the solvent to the total mass of bromoalkane and betaine is (1.5~5):1, preferably (2~3.5):1; and / or, The bromoalkane is 7-(bromomethyl)pentadecane; and / or, The solvent is acetonitrile; and / or, The reaction temperature is 70℃-120℃, preferably 80-90℃, and / or the reaction time is 4h-8h, preferably 5h-6h.

4. The pesticide nanocarrier according to claim 2, characterized in that: The It is prepared by reacting raw materials including alkyl sulfonic acid, betaine, alkyl alcohol and solvent; preferably, The molar ratio of the alkyl alcohol, betaine, and alkyl sulfonic acid is 2:(0.5~2):2, preferably 2:(1~1.2):2; and / or, The ratio of the solvent to the total mass of the alkyl alcohol, betaine, and alkyl sulfonic acid is (1~4):1, preferably (2~3):1; and / or, The alkyl sulfonic acid is methane sulfonic acid; and / or, The alkyl alcohol is 7-tetradecanoic acid and / or 9-heptadecanoic acid; and / or, The solvent is acetonitrile; and / or, The reaction temperature is 120~140℃, preferably 130~135℃, and / or the reaction time is 4h-8h, preferably 5h-6h.

5. A method for preparing a betaine-based surfactant composite sodium alginate pesticide nanocarrier as described in any one of claims 1-4, characterized in that... The method includes: An aqueous solution of sodium alginate is added dropwise to an aqueous solution of a surfactant, and the mixture is stirred to react, thereby obtaining the pesticide nanocarrier; preferably, The concentration of the aqueous solution of sodium alginate is 0.1-0.6 mg / mL, preferably 0.3-0.4 mg / mL; and / or, The concentration of the aqueous solution of the surfactant is 0.1-0.5 mg / mL, preferably 0.15-0.4 mg / mL; and / or, The dropping rate is 0.2-1 mL / min, and / or the rotation speed is 300-800 rpm; and / or, The stirring reaction is carried out at a speed of 300-800 rpm and / or for a time of 10-50 min.

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