Amphiphilic lipotic acid derivatives, methods for their preparation and use

Abstract

The present disclosure provides an amphiphilic lipolic acid derivative, a preparation method and application thereof, and belongs to the technical field of pesticides. The amphiphilic lipolic acid derivative is assembled by lipolic acid and amino acid / amino acid derivative through salt bridge, wherein the molar ratio of lipolic acid and amino acid / amino acid derivative is 1:1. The amphiphilic lipolic acid derivative forms an amphiphilic structure with a hydrophobic core and a hydrophilic surface layer through self-assembly, and the hydrophobic core can load hydrophobic pesticide molecules through hydrophobic interaction to form a carrier-free nano-pesticide without using other potentially harmful carrier materials or organic solvents.

Description

Technical Field

[0001] This disclosure relates to the field of pesticide technology, and in particular to an amphiphilic polythioctic acid derivative, its preparation method and application, and more specifically to an amphiphilic polythioctic acid derivative and its preparation method, a carrier-free nanopesticide and its preparation method and its application in agricultural sterilization. Background Technology

[0002] In agricultural production, most pesticides are prone to splashing and ejection during spraying due to the complex micro / nano structure, waxy layer, anisotropic wettability, and superhydrophobic properties of crop leaves. This results in less than 40% of the pesticide actually reaching the target crop surface, and less than 1% of the active ingredient reaching the target pest site. This off-target loss and the need for repeated reapplication not only significantly increase agricultural production costs but also exacerbate environmental damage.

[0003] To improve pesticide foliar affinity and deposition efficiency, various solutions have been explored. On one hand, strategies such as nanofibers, polymers, supramolecular hydrogels, surfactants, condensed phases, and supramolecular self-assembly are employed to suppress droplet bouncing and splashing on superhydrophobic leaf surfaces. Simultaneously, pesticide carriers tailored to plant surface roughness and micro / nanostructures are designed to enhance targeted deposition and retention. On the other hand, commercially available formulations such as emulsifiable concentrates and microemulsions have been developed for hydrophobic pesticides to achieve dispersion and application in aqueous phases. However, these methods often require the use of hazardous solvents such as toluene and xylene during production, and necessitate the addition of large amounts of thickeners and wetting / dispersing agents, posing significant risks to the environment and human health. Furthermore, while existing nanopesticides offer advantages in delivery efficiency, they still suffer from prominent issues such as difficult carrier degradation, harmful adjuvants, complex preparation processes, and potential environmental risks, requiring further optimization and improvement. Summary of the Invention

[0004] In view of this, the main objective of this disclosure is to provide an amphiphilic polythioctic acid derivative, its preparation method and application, in order to at least partially solve at least one of the aforementioned technical problems.

[0005] To achieve the above objectives, the technical solution disclosed herein is as follows:

[0006] In one aspect of this disclosure, an amphiphilic polylipoic acid derivative is provided, which is assembled from lipoic acid and an amino acid / amino acid derivative via a salt bridge, wherein the molar ratio of lipoic acid to amino acid / amino acid derivative is 1:1.

[0007] In a second aspect of this disclosure, a method for preparing the above-mentioned amphiphilic polythioctic acid derivative is provided, comprising:

[0008] Lipoic acid is dissolved in water with amino acids or amino acid derivatives and reacted with stirring at 40℃~70℃ to obtain amphiphilic polylipoic acid derivatives.

[0009] According to a third aspect of this disclosure, a carrier-free nanopesticide is provided, comprising nanoparticles formed by self-assembly of the aforementioned amphiphilic polythiooctanoic acid derivative and a hydrophobic pesticide.

[0010] According to the fourth aspect of this disclosure, a method for preparing the above-mentioned carrier-free nanopesticide is provided, comprising: stirring and mixing an amphiphilic polythiooctanoic acid derivative and an alcohol solution of a hydrophobic drug in water under conditions of pH 6.8 to 7.5 to form an initial product; and dialysis the initial product with water as a medium to obtain the carrier-free nanopesticide.

[0011] According to the fifth aspect of this disclosure, an application of the above-mentioned nanopesticide in agricultural sterilization is provided.

[0012] The amphiphilic polythioctic acid derivative disclosed herein is an amphiphilic polymer with a hydrophobic core and a hydrophilic surface structure, formed by the assembly of thioctic acid and amino acid derivatives via salt bridging. Its hydrophobic core can effectively encapsulate hydrophobic pesticide molecules, while the hydrophilic surface not only provides the system with aqueous dispersion stability but also possesses good interfacial adhesion and film-forming stability. This derivative requires no additional carrier or harmful adjuvants and can self-assemble with hydrophobic pesticides through hydrophobic interactions to form stable carrier-free nanoparticles, promoting pesticide spread and wetting on leaf surfaces. This reduces pesticide off-target losses and application costs, and avoids the environmental risks of toxic solvents and recalcitrant carriers from the source. Attached Figure Description

[0013] Figure 1 This is a schematic diagram illustrating the assembly principle of the amphiphilic polythiooctanoic acid derivative disclosed herein.

[0014] Figure 2 This disclosure provides a method for preparing carrier-free nanopesticides.

[0015] Figure 3 The in-situ Raman spectra of the amphiphilic polythiooctanoic acid derivatives in Examples 1 to 3 and Comparative Example 1 of this disclosure are shown below.

[0016] Figure 4 The fluorescence indicator diagrams are shown for the amphiphilic polythiooctanoic acid derivatives in Examples 1 to 3 and Comparative Example 1 of this disclosure.

[0017] Figure 5 Examples 1 to 3 and Comparative Example 1 of this disclosure illustrate the adhesion effect of the amphiphilic polythiooctanoic acid derivatives on the glass surface.

[0018] Figure 6a These are macroscopic photographs of the carrier-free nanopesticides in Examples 4 to 9;

[0019] Figure 6b This is a comparison chart of the particle size of carrier-free nanopesticides in Examples 4 to 9;

[0020] Figure 7 The diagram shows a comparison of the equilibrium surface tension of the amphiphilic polythiooctanoic acid derivatives in Examples 1-3 and Comparative Example 1, the carrier-free nanopesticides in Examples 7 and 10-11, and water. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments.

[0022] The endpoints and any values ​​of the ranges disclosed in this disclosure are not limited to the precise ranges or values, and such ranges or values ​​should be understood to include values ​​close to such ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this disclosure.

[0023] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0024] In agricultural production, hydrophobic pesticides are generally prone to splashing and ejection during spraying due to the micro / nano structure, waxy layer and superhydrophobic properties of crop leaves, resulting in low target deposition rates. In addition, traditional pesticide formulations require the use of harmful solvents and adjuvants, posing environmental and health risks. Existing nanopesticides also face problems such as difficult carrier degradation and complex preparation.

[0025] In realizing this disclosure, it was discovered that amphiphilic molecular multilevel assemblies based on self-assembly technology possess interfacial adaptability and drug loading capacity. Their dissipation mechanism, capable of withstanding significant deformation, can conformally adhere to leaf surfaces to enhance interfacial deposition. Furthermore, their flexible controllability of chemical composition and structure, as well as their sensitive response to environmental stimuli, provide a new direction for pesticide formulation development. However, it is necessary to regulate the selection of building blocks in these amphiphilic molecular multilevel assemblies to control important properties such as wettability and deposition properties.

[0026] Extensive research has led to the present disclosure of an amphiphilic polylipoic acid derivative, its preparation method, and its applications. Using lipoic acid (TA) as the building block, this method overcomes the limitation of TA's poor water solubility by constructing a structurally tunable amphiphilic polylipoic acid derivative (PTAX) in situ through salt-bridge interactions (carboxyl-amino interactions) between TA and amino acids / amino acid derivatives. As a vitamin-like biomass molecule, lipoic acid not only possesses strong antioxidant and UV photolysis resistance, protecting pesticide active ingredients, but also undergoes disulfide ring-opening polymerization under heat / light stimulation to form a stable polymeric structure, endowing the assembly with unique interfacial adhesion and stability. Furthermore, this disclosure further utilizes the hydrophobic and electrostatic interactions between PTAX and hydrophobic pesticide molecules to self-assemble stable carrier-free spherical nanoparticles without the addition of harmful solvents or carrier materials, by controlling the ratio of PTAX to hydrophobic pesticide molecules. It significantly improves the spreading, wetting, and deposition effects of pesticides on hydrophobic leaf surfaces, reduces off-target losses and the number of repeated applications, and avoids the environmental and health risks caused by harmful solvents and adjuvants from the source. At the same time, the carrier-free design solves the problems of difficult carrier degradation and potential environmental risks of traditional nanopesticides. While simplifying the preparation process, it provides innovative and practical technical support for the ecological and efficient development of agriculture.

[0027] According to one aspect of the present disclosure, an amphiphilic polylipoic acid derivative is provided, which is assembled from lipoic acid and an amino acid / amino acid derivative via a salt bridge, wherein the molar ratio of lipoic acid to amino acid / amino acid derivative is 1:1.

[0028] According to embodiments of this disclosure, lipoic acid molecules themselves contain hydrophobic groups such as long-chain alkyl groups and disulfide five-membered rings, and have poor water solubility. When lipoic acid is mixed with amino acids / amino acid derivatives in a 1:1 molar ratio, the carboxyl group (-COOH) of lipoic acid reacts with the amino group (-NH3) of the amino acid / amino acid derivatives. + Electrostatic interactions are generated, forming stable salt bridges that drive the rapid assembly of the two molecules. During this process, lipoic acid molecules undergo disulfide ring-opening polymerization to form a polylipoic acid backbone, while the originally dispersed hydrophobic groups of lipoic acid spontaneously aggregate due to hydrophobic interactions, forming a dense hydrophobic core region that retains its hydrophobic properties. Amino acids / amino acid derivatives are rich in hydrophilic groups, such as hydroxyl (-OH), guanidinyl (e.g., in arginine), and quaternary ammonium salt groups (e.g., in trimethylglycine). These hydrophilic groups are directionally exposed on the surface of the assembly, forming a continuous hydrophilic interface that, together with the hydrophobic core, constructs an amphiphilic polylipoic acid derivative with a hydrophobic core and a hydrophilic outer layer.

[0029] The hydrophobic core of amphiphilic polythioctic acid derivatives can specifically bind to hydrophobic drug molecules through hydrophobic interactions, thereby achieving drug loading; the hydrophilic surface can form hydrogen bonds and electrostatic interactions with the aqueous medium, giving the amphiphilic polythioctic acid derivatives good dispersion stability in the aqueous system, avoiding problems such as aggregation and stratification, while enhancing its adhesion to interfaces such as hydrophobic crop leaves, laying the foundation for the efficient deposition and action of subsequent pesticides.

[0030] According to embodiments of this disclosure, the amino acid / amino acid derivative includes any one of arginine, lysine, and trimethylglycine. In practical applications, the type of amino acid / amino acid derivative can be selected according to requirements to adapt to the loading requirements of different hydrophobic pesticides and the characteristics of different crop leaves, flexibly controlling the amphiphilicity, interfacial adhesion, and other properties of the assembly.

[0031] Figure 1 This is a schematic diagram illustrating the assembly principle of the amphiphilic polythiooctanoic acid derivative disclosed herein.

[0032] like Figure 1 As shown, all three amino acids / amino acid derivatives mentioned above contain a highly polar amino group (-NH3). + Furthermore, the amino groups exhibit high dissociation stability, rapidly forming strong electrostatic salt bridges with the carboxyl groups (-COOH) of thioctic acid. Simultaneously, all three molecules are rich in highly hydrophilic groups such as hydroxyl and guanidinyl (arginine), further enhancing the surface hydrophilicity of the amphiphilic polythioctic acid derivatives. Moreover, arginine, lysine, and trimethylglycine are all non-toxic and readily biodegradable, preventing the introduction of harmful chemical components and ensuring the environmental friendliness of the amphiphilic polythioctic acid derivatives and subsequent nano-pesticide formulations from the source.

[0033] According to an embodiment of the second aspect of this disclosure, a method for preparing the above-mentioned amphiphilic polythioctic acid derivative is provided, comprising: dissolving thioctic acid and an amino acid / amino acid derivative in water, and stirring the reaction at 40°C to 70°C to obtain the amphiphilic polythioctic acid derivative.

[0034] According to embodiments of this disclosure, lipoic acid and amino acids / amino acid derivatives are dissolved in an alcohol solution. The alcohol medium simultaneously enhances the solubility of both raw materials, ensuring sufficient molecular contact. The mixture is then stirred at a temperature of 40°C to 70°C. This temperature range accelerates the formation of stable salt bridges between the carboxyl groups of lipoic acid and the amino groups of the amino acids / amino acid derivatives, driving orderly molecular assembly and ultimately yielding an amphiphilic polylipoic acid derivative. This preparation method features mild reaction conditions and a simple, controllable process. Using an alcohol solvent, it eliminates the need for harmful additives and stringent reaction conditions, thus avoiding the environmental and health risks associated with traditional formulations.

[0035] According to embodiments of this disclosure, the stirring speed is 300 rpm to 500 rpm, for example, 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, etc.; the stirring time is 30 min to 5 h, for example, 30 min, 1 h, 2 h, 3 h, 4 h, 5 h, etc. By adjusting the stirring parameters and reaction time, uniform dispersion of raw materials and efficient intermolecular collisions are ensured, guaranteeing salt bridge formation and full reaction.

[0036] According to an embodiment of the third aspect of this disclosure, a carrier-free nanopesticide is provided, comprising nanoparticles formed by self-assembly of the aforementioned amphiphilic polythiooctanoic acid derivative and a hydrophobic pesticide.

[0037] According to embodiments of this disclosure, the amphiphilic polythiooctanoic acid derivative has a structure with a hydrophobic core and a hydrophilic surface. When mixed with a hydrophobic pesticide, the hydrophobic pesticide molecules interact with the hydrophobic microregions of the derivative core and spontaneously aggregate. Simultaneously, the hydrophilic groups on the derivative surface can form stable hydrogen bonds and electrostatic interactions with the aqueous medium, driving the system to self-assemble into stable nanoparticles. This carrier-free nanopesticide can achieve hydrophobic pesticide loading without the need for other carrier materials or harmful adjuvants. Furthermore, the hydrophilic groups on the surface enhance the wetting, adhesion, and deposition effects of the pesticide on hydrophobic leaf surfaces, reducing off-target losses during pesticide spraying.

[0038] According to embodiments of this disclosure, the molar ratio of the amphiphilic polythioctic acid derivative to the hydrophobic drug is 1:1 to 1:80, for example, 1:1, 1:51:10, 1:20, 1:40, 1:80, etc. More preferably, it is 1:1 to 1:40. This wide ratio range allows for flexible adaptation to the molecular structures and hydrophobic strengths of different hydrophobic pesticides. In practical applications, the pesticide loading can be adjusted according to the performance requirements of carrier-free nanopesticides. This allows for sufficient encapsulation of large-molecule, highly hydrophobic pesticides when using a higher ratio, while avoiding excessive damage to the assembly structure by small-molecule, weakly hydrophobic pesticides when using a lower ratio. Ultimately, while ensuring pesticide efficacy, improving leaf deposition rate, and reducing off-target losses, the derivative dosage is rationally controlled, taking into account multiple requirements such as formulation loading efficiency, dispersion stability, and production cost optimization.

[0039] According to embodiments of this disclosure, the average particle size of the nanoparticles is less than 1 μm, for example, it can be 900 nm, 700 nm, 500 nm, 300 nm, 100 nm, 50 nm, etc. The smaller particle size ensures that the carrier-free nanopesticides of this disclosure are stably dispersed in an aqueous system, are not prone to aggregation and sedimentation, and are easy to spray evenly; at the same time, the small particle size characteristic can significantly increase the contact area between the nanoparticles and the crop leaf surface. Combined with the hydrophilic groups on the surface of the amphiphilic polythiooctanoic acid derivative, the wetting and adhesion effect of the particles on the hydrophobic leaf surface can be further improved, reducing pesticide loss and off-target loss during spraying.

[0040] According to embodiments of this disclosure, the hydrophobic pesticide includes any one of spinosad, pyraclostrobin, ethoxysulfuron, and imidacloprid. In practical applications, a suitable hydrophobic pesticide can be selected based on the type of pest or disease being controlled, the crop variety, etc.

[0041] For example, when the hydrophobic drug is spinosad (SSD), the positively charged amino group in the SSD molecule can generate additional electrostatic interactions with the negatively charged carboxyl group at the tail of the amphiphilic polythioctic acid derivative (PTAX). This interaction forms a synergistic effect with the hydrophobic interaction, promoting intermolecular entanglement and further facilitating the self-assembly of the system to form nanoparticles with uniform particle size and stable structure.

[0042] Figure 2 This disclosure provides a method for preparing carrier-free nanopesticides.

[0043] According to an embodiment of the fourth aspect of this disclosure, such as Figure 2 As shown, a method for preparing the above-mentioned carrier-free nanopesticide is provided, comprising: stirring and mixing an amphiphilic polythiooctanoic acid derivative and an alcohol solution of a hydrophobic drug in water under conditions of pH 6.8-7.5 to form an initial product; and dialysis the initial product with water as a medium to obtain the carrier-free nanopesticide.

[0044] According to embodiments of this disclosure, a near-neutral pH range of 6.8–7.5 ensures the stability of the amphiphilic structure of the "hydrophobic core-hydrophilic surface" formed by the salt bridge-dependent formation of the amphiphilic polythiooctanoic acid derivative, preventing assembly dissociation and protecting the molecular structure of the hydrophobic pesticide, thus preventing its efficacy from being reduced due to hydrolysis and decomposition in acidic or alkaline environments. Furthermore, the hydrophobic core of the derivative interacts with the hydrophobic pesticide molecules, promoting spontaneous aggregation of pesticide molecules towards the core. Simultaneously, the electrostatic synergistic effect between the derivative and some pesticide molecules further drives the self-assembly of the system, forming stable nanoparticles. Moreover, this preparation method is simple, requiring no additional pH adjusters or adjuvants, significantly simplifying the operation steps while mitigating the risk of pesticide damage to crops from reagent residues.

[0045] According to an embodiment of the fourth aspect of this disclosure, an application of the above-mentioned nanopesticide in agricultural sterilization is provided.

[0046] According to embodiments of this disclosure, the hydrophobic core of carrier-free nanopesticides can effectively encapsulate hydrophobic bactericidal components. At the same time, due to their small particle size and hydrophilic surface structure, they can significantly improve the wetting, adhesion and deposition effects on crop leaves, effectively reducing pesticide loss. Furthermore, this nanopesticide does not require carrier materials or harmful adjuvants, and there is no risk of residual pollution after spraying. It can improve bactericidal efficiency, reduce the frequency and amount of pesticide application in the field, and ensure the safety of crops and the ecological environment.

[0047] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments. Unless otherwise specified, all methods described in the embodiments are conventional and can be performed according to the techniques or conditions described in the literature or the product manual.

[0048] The α-lipoic acid (LA, 99%), arginine, lysine, and betaine used in the embodiments of this disclosure were all purchased from Adamas (Shanghai, China). Sodium hydroxide (NaOH, ≥96%) was purchased from Maclean Chemical Reagent Co., Ltd. (Shanghai, China). All reagents were used without further purification.

[0049] Example 1:

[0050] Example 1 of this disclosure provides an amphiphilic polythiooctanoic acid derivative 1. The preparation method of this amphiphilic polythiooctanoic acid derivative 1 is as follows.

[0051] In an aqueous solution, α-lipoic acid and arginine were mixed at a molar ratio of 1:1 and stirred at 50°C for 3 hours to form the initial product.

[0052] The initial product was dialyzed with water to obtain amphiphilic polythiooctanoic acid derivative 1 (PTAA).

[0053] Example 2:

[0054] Example 2 of this disclosure provides an amphiphilic polythiooctanoic acid derivative 2. The preparation method of this amphiphilic polythiooctanoic acid derivative 2 is as follows.

[0055] In an aqueous solution, α-lipoic acid and lysine were mixed at a molar ratio of 1:1 and stirred at 50°C for 3 hours to form the initial product.

[0056] The initial product was dialyzed with water to obtain amphiphilic polythiooctanoic acid derivative 2 (PTAL).

[0057] Example 3:

[0058] Example 3 of this disclosure provides an amphiphilic polythiooctanoic acid derivative 3. The preparation method of this amphiphilic polythiooctanoic acid derivative 3 is as follows.

[0059] In an aqueous solution, α-lipoic acid and trimethylglycine were mixed at a molar ratio of 1:1 and stirred at 50°C for 3 hours to form the initial product.

[0060] The initial product was dialyzed with water to obtain amphiphilic polythiooctanoic acid derivative 3 (PTAB).

[0061] Comparative Example 1

[0062] Comparative Example 1 of this disclosure provides an amphiphilic polythiooctanoic acid derivative 4. The preparation method of this amphiphilic polythiooctanoic acid derivative 4 is as follows.

[0063] 0.15 mol lipoic acid and 0.15 mol NaOH were stirred for 3 h to obtain a homogeneous solution, which was then freeze-dried to obtain sodium lipoate (TAN).

[0064] TAN was dissolved in water and stirred at 50°C for 3 hours to obtain sodium polythiooctanoate (PTAN).

[0065] Figure 3 The images show the in-situ Raman spectra of the amphiphilic polythiooctanoic acid derivatives in Examples 1 to 3 and Comparative Example 1 of this disclosure.

[0066] like Figure 3 As shown, at 2909 cm -1 The stretching vibration peak of the carbon-hydrogen (CH) bond at 511 cm⁻¹, and the peak at 511 cm⁻¹. -1 The characteristic peak of the stretching vibration of the disulfide bond (SS) at the location indicates that polythioctic acid derivatives were prepared in Examples 1 to 3 and Comparative Example 1.

[0067] The aggregation behavior and drug loading potential of the amphiphilic polythioctic acid derivatives in Examples 1-3 and Comparative Example 1 were demonstrated using aggregation-induced emission fluorescent molecular indicators.

[0068] Figure 4 The images show fluorescence indicators of the amphiphilic polythiooctanoic acid derivatives in Examples 1 to 3 and Comparative Example 1 of this disclosure.

[0069] like Figure 4 As shown, under UV irradiation for 0–24 h, droplets of amphiphilic polythioctic acid derivatives containing aggregation-induced luminescence (AIL) fluorescent molecules all exhibited distinct blue fluorescence. This indicates that the hydrophobic fluorescent molecules successfully entered and aggregated in the hydrophobic microregions of PTAA, PTAL, PTAB, and PTAN, thereby inducing luminescence. This verifies that the above derivatives all possess amphiphilic properties and the ability to encapsulate hydrophobic active ingredients.

[0070] Furthermore, by observing the film-forming and adhesion behavior of the amphiphilic polythiooctanoic acid derivatives on solid surfaces in Examples 1-3 and Comparative Example 1, their interfacial retention capacity in practical applications was tested.

[0071] Figure 5 Examples 1 to 3 and Comparative Example 1 of this disclosure illustrate the adhesion effect of the amphiphilic polythiooctanoic acid derivatives on the glass surface.

[0072] like Figure 5 As shown, after drying, the PTAA film obtained in Example 1 exhibited good transparency and integrity, achieving strong adhesion to the glass surface without cracking or detachment. The films of Example 2 (PTAL) and Example 3 (PTAB) also exhibited similar good adhesion properties. In contrast, the PTAN film obtained in Comparative Example 1 showed significant cracking after drying and detached from the substrate. This indicates that the PTAA, PTAL, and PTAB derivatives obtained by amino acid modification in this disclosure have better interfacial adhesion and film-forming stability than PTAN, which is beneficial for promoting the persistent deposition and retention of pesticide droplets on the hydrophobic leaf surfaces of target crops and reducing runoff caused by rainwater erosion.

[0073] Example 4

[0074] Embodiment 4 of this disclosure provides a carrier-free nanopesticide 1, and the preparation method of the carrier-free nanopesticide 1 is as follows.

[0075] Under pH 7.5 conditions, the amphiphilic polythioctic acid derivative PTAA prepared in Example 1 was mixed with a methanol solution of spinosad (SSD) in water by stirring, wherein the molar ratio of PTAA to SSD was 1:1 to obtain carrier-free nanopesticide 1.

[0076] Example 5

[0077] Embodiment 5 of this disclosure provides a carrier-free nanopesticide 2, and the preparation method of the carrier-free nanopesticide 2 is as follows.

[0078] At a pH of 7.5, the amphiphilic polythioctic acid derivative PTAA prepared in Example 1 was mixed with a methanol solution of spinosad (SSD) in water by stirring, wherein the molar ratio of PTAA to SSD was 1:5, to obtain carrier-free nanopesticide 2.

[0079] Example 6

[0080] Embodiment 6 of this disclosure provides a carrier-free nanopesticide 3, and the preparation method of the carrier-free nanopesticide 3 is as follows.

[0081] At a pH of 7.5, the amphiphilic polythioctic acid derivative PTAA prepared in Example 1 was mixed with spinosad (SSD) at a molar ratio of 1:10 to obtain carrier-free nanopesticide 3.

[0082] Example 7

[0083] Embodiment 7 of this disclosure provides a carrier-free nanopesticide 4, and the preparation method of the carrier-free nanopesticide 4 is as follows.

[0084] At a pH of 7.5, the amphiphilic polythioctic acid derivative PTAA prepared in Example 1 was mixed with a methanol solution of spinosad (SSD) in water by stirring, wherein the molar ratio of PTAA to SSD was 1:20, to obtain carrier-free nanopesticide 4.

[0085] Example 8

[0086] Embodiment 8 of this disclosure provides a carrier-free nanopesticide 5, and the preparation method of the carrier-free nanopesticide 5 is as follows.

[0087] At a pH of 7.5, the amphiphilic polythioctic acid derivative PTAA prepared in Example 1 was mixed with a methanol solution of spinosad (SSD) in water by stirring, wherein the molar ratio of PTAA to SSD was 1:40 to obtain carrier-free nanopesticide 5.

[0088] Example 9

[0089] This disclosure provides a carrier-free nanopesticide 6, and the preparation method of the carrier-free nanopesticide 6 is as follows.

[0090] At a pH of 7.5, the amphiphilic polythioctic acid derivative PTAA prepared in Example 1 was mixed with a methanol solution of spinosad (SSD) in water by stirring, wherein the molar ratio of PTAA to SSD was 1:80, to obtain carrier-free nanopesticide 6.

[0091] Example 10

[0092] This disclosure provides a carrier-free nanopesticide 7, and the preparation method of the carrier-free nanopesticide 7 is as follows.

[0093] At a pH of 7.5, the amphiphilic polythioctic acid derivative PTAL prepared in Example 2 was mixed with a methanol solution of spinosad (SSD) in water by stirring, wherein the molar ratio of PTAL to SSD was 1:20, to obtain carrier-free nanopesticide 7.

[0094] Example 11

[0095] This disclosure provides a carrier-free nanopesticide 8, and the preparation method of the carrier-free nanopesticide 8 is as follows.

[0096] Under pH 7.5 conditions, the amphiphilic polythioctic acid derivative PTAB prepared in Example 1 was mixed with a methanol solution of spinosad (SSD) in water by stirring, wherein the molar ratio of PTAB to SSD was 1:20, to obtain carrier-free nanopesticide 8.

[0097] Comparative Example 2

[0098] Comparative Example 2 of this disclosure provides a carrier-free nanopesticide 9, and the preparation method of the carrier-free nanopesticide 9 is as follows.

[0099] Under pH 7.5 conditions, the amphiphilic polythioctic acid derivative PTAN prepared in Comparative Example 1 was mixed with a methanol solution of spinosad (SSD) in water by stirring, wherein the molar ratio of PTAN to SSD was 1:20, to obtain carrier-free nanopesticide 9.

[0100] The appearance and particle size of the carrier-free nanopesticides in Examples 4 to 9 were tested.

[0101] Figure 6a These are macroscopic photographs of carrier-free nanopesticides from Examples 4 to 9.

[0102] Figure 6b The image shows a comparison of the particle size of carrier-free nanopesticides in Examples 4 to 9.

[0103] like Figure 6a As shown, the Tyndall effect can be used to observe the carrier-free nanopesticide systems in Examples 4 to 9. When the molar ratio of PTAA to SSD is in the range of 1:1 to 80, the system can exhibit a bright Tyndall light path. Among them, when the molar ratio is 1:20, the system exhibits the brightest Tyndall light path.

[0104] like Figure 6b As shown, by adjusting the molar ratio of PTAA to SSD, carrier-free nanopesticides have a particle size of less than 700 nm. At a molar ratio of 1:20, the nanopesticide particles have the smallest particle size.

[0105] Figure 7 The diagram shows a comparison of the equilibrium surface tension of the amphiphilic polythiooctanoic acid derivatives in Examples 1-3 and Comparative Example 1, the carrier-free nanopesticides in Examples 7 and 10-11, and water.

[0106] like Figure 7As shown, the surface tension of water is approximately 72 mN / m. The amphiphilic derivatives formed in Examples 1 (PTAA), 2 (PTAL), 3 (PTAB), and Comparative Example 1 (PTAN) have a reduced surface tension of approximately 55-65 mN / m due to their hydrophilic outer layer. The carrier-free nanopesticides in Examples 7 (PTAA / SSD), 10 (PTAL / SSD), and 11 (PTAB / SSD) exhibit a more uniform distribution and fuller exposure of polar groups on the hydrophilic surface due to the hydrophobic interaction between the hydrophobic pesticide molecule (SSD) and the hydrophobic core of the amphiphilic polythiooctanoic acid derivative. This more effectively weakens the cohesive forces between water molecules, significantly enhancing the surface activity of the system and reducing the surface tension to below 50 mN / m.

[0107] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. An amphiphilic polythiooctanoic acid derivative, characterized in that, The amphiphilic polylipoic acid derivative is assembled from lipoic acid and amino acid / amino acid derivatives via salt bridging, wherein the molar ratio of lipoic acid to amino acid / amino acid derivative is 1:

1.

2. The amphiphilic polythiooctanoic acid derivative according to claim 1, characterized in that, The amino acid / amino acid derivative includes any one of arginine, lysine, and trimethylglycine.

3. A method for preparing the amphiphilic polythiooctanoic acid derivative as described in claim 1 or 2, characterized in that, The preparation method includes: The amphiphilic polythioctic acid derivative is obtained by dissolving thioctic acid and the amino acid or amino acid derivative in water and stirring at 40℃~70℃.

4. The preparation method according to claim 3, characterized in that, The stirring speed is 300 rpm to 500 rpm, and the stirring time is 30 min to 5 h.

5. A carrier-free nanopesticide, characterized in that, The nanopesticide is formed by the self-assembly of the amphiphilic polythiooctanoic acid derivative as described in any one of claims 1 to 2 and a hydrophobic pesticide into nanoparticles.

6. The nano-pesticide according to claim 5, characterized in that, The molar ratio of the amphiphilic polythioctic acid derivative to the hydrophobic drug is 1:1 to 1:

40.

7. The nano-pesticide according to claim 5, characterized in that, The average particle size of the nanoparticles is less than 1 μm.

8. The nanopesticide according to claim 5, characterized in that, The hydrophobic agents include any one of spinosad, pyraclostrobin, ethoxysulfuron, and imidacloprid.

9. A method for preparing a carrier-free nanopesticide according to any one of claims 5 to 8, characterized in that, The preparation method includes: Under conditions of pH 6.8–7.5, the amphiphilic polythioctic acid derivative and the alcohol solution of the hydrophobic drug were stirred and mixed in water to form the initial product. The initial product was dialyzed with water to obtain a carrier-free nanopesticide.

10. The application of a nano-pesticide as described in any one of claims 5 to 8 in agricultural sterilization.

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