A nanogel for enhancing downward translocation and penetration of tebuconazole and a preparation method thereof

Abstract

The application discloses a kind of nanogel of enhancing pentazocine downward conduction penetration and preparation method thereof, belong to chemical pesticide technical field.The application obtains oil phase by mixing pentazocine, N-methyl pyrrolidone, isobutyl methacrylate, ammonium persulfate, deionized water is mixed to obtain aqueous phase, after two phases are mixed, under stirring, drop into n-butyl alcohol and C-2 emulsifier, by nitrogen, heating reaction obtains nanogel.The average particle size of nanogel prepared in the application is about 25 nm, can significantly reduce the surface tension of liquid medicine, improve its wetting and spreading property on hydrophobic crop leaf surface, effectively inhibit liquid drop bounce and roll;At the same time, ultra-small particle size enhances the downward conduction penetration ability of liquid medicine in wheat plant, and gives pentazocine excellent anti photolysis and slow-release performance.Compared with commercially available suspending agent, the product of the application has better inhibition effect on hordeum vulgare, and has good safety to non-target organism, has wide application prospect in the field of pesticide reduction and efficiency increase.

Description

Technical Field

[0001] This invention belongs to the field of chemical pesticide technology, specifically relating to a nanogel that enhances the downward conduction and permeation of tebuconazole and its preparation method. Background Technology

[0002] Wheat is one of the most widely planted and highest-yielding food crops globally, and its stable and high yields are of paramount strategic importance. However, throughout its entire growth cycle, wheat is frequently attacked by various fungal diseases, especially Fusarium head blight, which not only severely reduces wheat yields but also produces mycotoxins that significantly degrade grain quality, threatening human and animal health. Currently, chemical control remains the most direct and effective means of controlling wheat diseases due to its advantages of rapid effectiveness and relatively controllable costs.

[0003] While chemical pesticides have played an indispensable role in ensuring agricultural harvests, traditional pesticide formulations (such as emulsifiable concentrates and wettable powders) generally suffer from low effective utilization rates. Due to poor wetting and spreading properties of pesticide solutions on crop leaves, large amounts of the solution drift, bounce, or run off into the soil and water bodies during spraying, resulting not only in significant resource waste but also serious non-point source pollution and the risk of pesticide residue exceeding standards. Therefore, utilizing modern nanotechnology to construct novel drug delivery systems, improving the dispersibility of hydrophobic drugs and enhancing their adhesion and penetration capabilities on crop surfaces, has become an important approach to improving pesticide formulations.

[0004] Tebuconazole, a highly effective triazole fungicide, is widely used to control fungal diseases such as wheat scab. However, in practical agricultural applications, existing commercial tebuconazole formulations still have many limitations, severely restricting their efficacy and safety. Firstly, regarding physicochemical properties and stability, tebuconazole has poor water solubility and is sensitive to light, easily undergoing photodegradation under natural light, leading to a shortened effective period. This often necessitates increasing application frequency or dosage to maintain efficacy. Secondly, regarding deposition and translocation on target crops, wheat leaves have significant hydrophobic properties due to the waxy layer. Traditional formulations have high surface tension, making it difficult for the sprayed droplets to spread on the leaf surface, easily causing bouncing and rolling, resulting in significant pesticide loss. Simultaneously, existing formulations typically have large particle sizes, making it difficult to penetrate the dense wheat canopy and translocate downwards, failing to effectively cover the lower parts of the plant where pathogens thrive, creating blind spots in disease control. In addition, in terms of environmental and biological safety, traditional emulsifiable concentrates and other formulations usually contain large amounts of organic solvents such as benzene or high concentrations of adjuvants. This not only poses a high risk of toxicity to non-target aquatic organisms, but long-term use may also cause phytotoxicity to crop growth.

[0005] Therefore, developing a novel tebuconazole nanodelivery system that is simple to prepare, can simultaneously achieve high resistance to photodegradation, excellent leaf surface affinity, ultra-small particle size to enhance permeability, and good environmental and biological safety has become an urgent technical problem to be solved in the field of pesticide formulation. Summary of the Invention

[0006] In view of this, the present invention aims to provide a nanogel that enhances the downward conduction and permeation of tebuconazole and its preparation method.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing a nanogel that enhances the downward conduction and permeation of tebuconazole, comprising the following steps: S1. Tebuconazole, N-methylpyrrolidone, and isobutyl methacrylate are mixed evenly to obtain an oil phase; S2. Mix ammonium persulfate and deionized water thoroughly to form the aqueous phase; S3. After mixing the oil phase and the water phase evenly, n-butanol and C-2 emulsifier are added dropwise while stirring. Then, nitrogen gas is introduced and the temperature is raised to react and obtain the nanogel formulation of tebuconazole.

[0008] Preferably, the ratio of tebuconazole, N-methylpyrrolidone, and isobutyl methacrylate in S1 is (1-1.3):(1):(1-1.3). Preferably, the ratio of ammonium persulfate to deionized water in S2 is 1:6266.

[0009] Preferably, the ratio of oil phase to water phase in S3 is 1:(1-1.5).

[0010] Preferably, the stirring speed in step S3 is 200-500 rpm.

[0011] Preferably, the ratio of n-butanol to C-2 emulsifier in S3 is 1:(2.25-2.5). The amounts of n-butanol and C-2 emulsifier added are 8% and 18% of the system mass, respectively. The C-2 emulsifier is a compound of 80% tristyrene-phenol polyoxyethylene ether and 20% alkyl sulfate.

[0012] Preferably, the temperature of the heating reaction in S3 is 65°C, and the reaction time is 6 hours.

[0013] The present invention also provides nanogels prepared by the above-described preparation method.

[0014] It contains at least the following beneficial technical effects: Compared to commercially available suspensions (TEB SC), this invention improves the storage stability and UV resistance of the nanogel system. The smaller particle size slows down droplet retraction and rebound rates, enhances affinity for leaf surfaces, and effectively inhibits droplet rebound. Due to the structural characteristics of TINF, pH-controlled release of TEB is achieved. TINF significantly enhances the downward transport efficiency of TEB within plants and its antibacterial activity against Fusarium graminearum. Attached Figure Description

[0015] Figure 1 For the multiple light scattering stability of nanogels, (A) TINF; (B) TEB SC; (C) TSI value; Figure 2 (A) TEM; (B) Particle size distribution of nanogel particles; Figure 3 (A) Fluorescence intensity; (B) TEB SC; (C) Stem transport factor; The downward transport of nanogels and commercial formulations is shown. Figure 4 The release of the nanogel at different pH values; Figure 5 The bouncing behavior of the nanogel droplets; Figure 6 This image shows the inhibitory effect of nanogel microemulsion on Fusarium graminearum, the causal agent of wheat blight. Detailed Implementation

[0016] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0017] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0018] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0019] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0020] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0021] Unless otherwise specified, "room temperature" and "normal temperature" in this invention refer to 25±2℃.

[0022] Unless otherwise specified, all raw materials or instruments used in the following embodiments of the present invention are commercially available.

[0023] Example 1 This embodiment provides a method for preparing a nanogel that enhances the downward conduction and permeation of tebuconazole, specifically including the following steps: S1. Tebuconazole, N-methylpyrrolidone, and isobutyl methacrylate are mixed evenly in a ratio of 1.2:1:1.2 to obtain the oil phase; S2. Mix ammonium persulfate and deionized water at a ratio of 1:6266 to form the aqueous phase; S3. After mixing the oil phase and the aqueous phase evenly at a ratio of 1:1.3, n-butanol and C-2 emulsifier are added dropwise while stirring. The C-2 emulsifier is a compound of 80% tristyrene-phenylphenol polyoxyethylene ether and 20% alkyl sulfate, and the ratio of n-butanol to C-2 emulsifier is 1:2.25. Then, nitrogen gas is introduced and the temperature is raised to 65°C. The reaction is carried out for 6 hours to obtain the nanogel formulation of tebuconazole.

[0024] Example 2 This embodiment provides a method for preparing a nanogel that enhances the downward conduction and permeation of tebuconazole, specifically including the following steps: S1. Tebuconazole, N-methylpyrrolidone, and isobutyl methacrylate are mixed evenly in a 1:1:1 ratio to obtain the oil phase; S2. Mix ammonium persulfate and deionized water at a ratio of 1:6266 to form the aqueous phase; S3. After mixing the oil phase and the water phase in a 1:1 ratio, n-butanol and C-2 emulsifier are added dropwise while stirring. The C-2 emulsifier is a compound of 80% tristyrene-phenylphenol polyoxyethylene ether and 20% alkyl sulfate, and the ratio of n-butanol to C-2 emulsifier is 1:2.4. Then, nitrogen gas is introduced and the temperature is raised to 65°C. The reaction is carried out for 6 hours to obtain the nanogel formulation of tebuconazole.

[0025] Example 3 This embodiment provides a method for preparing a nanogel that enhances the downward conduction and permeation of tebuconazole, specifically including the following steps: S1. Tebuconazole, N-methylpyrrolidone, and isobutyl methacrylate are mixed evenly in a ratio of 1.3:1:1.3 to obtain the oil phase; S2. Mix ammonium persulfate and deionized water at a ratio of 1:6266 to form the aqueous phase; S3. After mixing the oil phase and the aqueous phase evenly at a ratio of 1:1.5, n-butanol and C-2 emulsifier are added dropwise while stirring. The C-2 emulsifier is a compound of 80% tristyrene-phenylphenol polyoxyethylene ether and 20% alkyl sulfate, and the ratio of n-butanol to C-2 emulsifier is 1:2.5. Then, nitrogen gas is introduced and the temperature is raised to 65°C. The reaction is carried out for 6 hours to obtain the nanogel formulation of tebuconazole.

[0026] Experimental Example 1 2. Performance Testing This embodiment tests the physical stability of the nanogel prepared in Example 1.

[0027] Using TurBiscan Lab Expert The multi-scattering stability of the samples was determined using a multiple light scattering analyzer. Approximately 20 mL of undiluted gel sample was poured into a cylindrical glass cell. The length of the sample (approximately 40 mm) was scanned using a measuring probe, with measurements taken every 40 μm from the bottom to the top of the cell to obtain the transmittance values. All samples were scanned every 1 hour at 25°C for a total of 24 hours to obtain stability characteristic maps. The Turbiscan stability index (TSI) was calculated using TurBiscan Easysoft software. A commercially available 430 g / L tebuconazole suspension was used as a control.

[0028] like Figure 1 As shown, the results indicate that during the 24-hour storage period, the backscattered light intensity of the nanogel formulation (TINF) remained unchanged over time, indicating that the particles did not aggregate, settle, or change in size. In contrast, the backscattered light intensity of the commercial suspension concentrate (TEB SC) changed significantly at both the bottom and top of the solution, indicating that the pesticide particles underwent stratification and sedimentation. The TSI value of TINF was less than 0.2, significantly lower than that of TEB SC, demonstrating that the nanogel formulation has good suspension stability.

[0029] Experimental Example 2 3. Particle size determination This embodiment measures the particle size of the nanogel prepared in Example 1.

[0030] The particle size of the gel samples was measured using a nanolaser particle size analyzer, with the test repeated five times and the average value calculated. Simultaneously, the sample morphology was observed using a transmission electron microscope.

[0031] like Figure 2 As shown, the results indicate that TINF exhibits a significant Tyndall effect, with the particle size, polydispersity index (PDI), and Zeta potential of TINF measured by dynamic light scattering (DLS) being 25.27 nm, 0.166, and -28.63 mV, respectively. Transmission electron microscopy (TEM) results show that the TINF particles are uniformly distributed and do not aggregate.

[0032] Experimental Example 3 This embodiment examines the downward conduction ability of the nanogel prepared in Example 1 within wheat plants.

[0033] The nanogel was labeled using a fluorescent labeling method with Nile Red as a fluorescent probe. TINF and TEB SC solutions were diluted to 40 mg / L, and the diluted solution was then applied to wheat leaves with a cotton swab. The seedlings were then placed in Hoagland nutrient solution and cultured for 6, 12, and 24 h before sectioning and observation. The fluorescence intensity was measured, with commercially available 430 g / L tebuconazole suspension as a control.

[0034] The accumulation trend of the herbicide solution within the plant was characterized by transpiration factor (TF), further evaluating the transfer potential of the herbicide solution from leaves to stems and roots. Calculations were performed according to equations (1)-(2):

[0035] in C leaf , C stem and C root (mg / L) represent the concentrations of TEB in the leaves, stems, and roots, respectively.

[0036] like Figure 3 The results showed that after treating the TINF system with Nile Red (NR, a lipophilic molecule) for 6, 12, and 24 h, red fluorescence signals were detected in the roots using confocal laser scanning microscopy (CLSM), indicating that TINF had been translocated from the leaves to the roots. The fluorescence intensity of TINF and TEB SC was compared, and the results showed that the concentration of NR in the roots increased over time. Furthermore, NR-TINF exhibited the highest fluorescence intensity. TF... r / l and TF s / l The TF value characterizes the translocation capacity of TEB from leaves to roots. Within 6–24 h, the TF values ​​of the two solutions... r / l Value greater than TF s / lValues, where TF of TINF and TEB SC r / l The values ​​increased by 1.26 times and 1.44 times respectively, and the TF of TINF r / l The value is greater than TEB SC, indicating that smaller particle size enables long-distance translocation from leaves to roots, demonstrating the superiority of TINF in long-distance translocation. It significantly enhances the downward translocation and penetration capacity of tebuconazole.

[0037] Experiment Example 4 Slow release This embodiment measures the release behavior of the nanogel prepared in Example 1 at different pH values.

[0038] The dialysis bag method was used, in which the nanogel sample was placed in a dialysis bag and immersed in buffer solutions with pH values ​​of 5, 7 and 9 respectively. The concentration of tebuconazole in the release medium was measured at set time points, and the cumulative release rate was calculated.

[0039] like Figure 4 As shown, the results indicate that TINF exhibits a particularly sensitive pH response, with a significantly accelerated release rate under alkaline conditions. TINF release is rapid within the first 30 hours, with cumulative release rates reaching 41.8%, 57.5%, and 65.8% at pH 5, 7, and 9, respectively. After 30 hours, the release rate slows down as TINF gradually diffuses into the surrounding medium. The final cumulative release of TINF after 180 hours is 63.6% at pH 5, 93.3% at pH 7, and 98.7% at pH 9. This phenomenon is attributed to the fact that acidic conditions slow down the hydrolysis of IBMA ester groups, ensuring the integrity and compactness of the gel network structure, thus reducing the release rate.

[0040] Experimental Example 5 Jump test This embodiment examines the dynamic behavior of the nanogel droplets prepared in Example 1 on a hydrophobic surface.

[0041] A high-speed camera system was used to record the spreading, retraction, and bouncing process of droplets after impacting wheat leaves from a fixed height (15 cm). A commercially available 430 g / L tebuconazole suspension was used as a control.

[0042] like Figure 5As shown, the results indicate that after impacting the leaf, TEB SC droplets exhibit significant retraction and rebound, making it difficult for them to adhere to the leaf. Conversely, TINF droplets show a significantly reduced retraction rate, do not rebound from the leaf surface, and ultimately form spherical droplets that adhere to the leaf. When pesticide droplets impact wheat leaves at an angle, TEB SC droplets almost completely roll off the leaf due to insufficient adhesion. In contrast, TINF droplets exhibit good interaction with the wheat leaf, making it difficult for them to roll off and ultimately remaining on the wheat leaf.

[0043] Experimental Example 6 Control efficacy against wheat scab This embodiment measures the toxicity of the nanogel prepared in Example 1 against Fusarium graminearum, the causal agent of wheat blight.

[0044] The inhibitory effect of TINF solution on Fusarium graminearum was evaluated using the mycelial growth method. After culturing the tested strains on PDA plates for 5 days, mycelial pellets with a diameter of 5 mm were punched out and inoculated onto PDA-containing medium plates containing TINF and TEB SC at concentrations of 0.025, 0.05, 0.1, 0.2, and 0.4 mg / L. Plates without the drug and a blank gel preparation served as controls. The plates were incubated at 25°C in the dark. When the colony diameter in the control group reached 80 mm, the colony diameter of each plate was measured using the cross-crossing method. The experiment was repeated three times, and the inhibition rate was calculated according to formula (1).

[0045]

[0046] like Figure 6 As shown, to evaluate the antibacterial activity of the nanogel formulation against Fusarium graminearum, the mycelial growth rate method was used to determine the inhibitory effect, and the median lethal concentration (EC50) was calculated. 50 TEB SC, blank gel BINF and sterile water were used as controls.

[0047] The results showed that in all treatment groups, with increasing TEB concentration, both TINF and TEB SC inhibited the hyphal growth diameter of *Fusarium graminearum*, with TINF exhibiting the strongest inhibitory activity. The blank gel BINF, however, did not inhibit hyphal growth. (The results were obtained via EC...) 50 This indicates the antibacterial effects of different solutions. As shown in Table 1, the EC values ​​of TINF and TEB SC... 50 The values ​​were 0.07 mg / L (0.059–0.09, 95% confidence interval) and 0.14 mg / L (0.114–0.178, 95% confidence interval), indicating that TINF exhibited high antibacterial activity.

[0048] Table 1. Virulence effects of nanogel formulations against Fusarium graminearum

[0049] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a nanogel that enhances the downward conduction and permeation of tebuconazole, characterized in that, Includes the following steps: S1. Tebuconazole, N-methylpyrrolidone, and isobutyl methacrylate are mixed evenly to obtain an oil phase; S2. Mix ammonium persulfate and deionized water thoroughly to form the aqueous phase; S3. After mixing the oil phase and the water phase evenly, n-butanol and C-2 emulsifier are added dropwise under stirring to control the final particle size. Then, nitrogen gas is introduced and the temperature is raised to react and obtain the nanogel formulation of tebuconazole.

2. The preparation method according to claim 1, characterized in that, The volume ratio of tebuconazole, N-methylpyrrolidone, and isobutyl methacrylate in S1 is (1-1.3):(1):(1-1.3).

3. The preparation method according to claim 1, characterized in that, The volume ratio of ammonium persulfate to deionized water in S2 is 1:6266.

4. The preparation method according to claim 1, characterized in that, The volume ratio of the oil phase to the water phase in S3 is 1:(1-1.5).

5. The preparation method according to claim 1, characterized in that, The stirring speed in S3 is 200-500 rpm.

6. The preparation method according to claim 1, characterized in that, The volume ratio of n-butanol to C-2 emulsifier in S3 is 1:(2.25-2.5). The amounts of n-butanol and C-2 emulsifier added are 8% and 18% of the system mass, respectively. The C-2 emulsifier is a compound of 80% tristyrene-phenol polyoxyethylene ether and 20% alkyl sulfate.

7. The preparation method according to claim 1, characterized in that, The temperature of the heating reaction in S3 is 65°C, and the reaction time is 6 hours.

8. The nanogel prepared by the preparation method according to any one of claims 1-7.

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