CN111631213A

CN111631213A - Drug-loaded gel and preparation method thereof

Info

Publication number: CN111631213A
Application number: CN202010573051.9A
Authority: CN
Inventors: 曹冲; 黄啟良; 宋玉莹; 郑丽; 曹立冬; 李凤敏; 赵鹏跃
Original assignee: Institute of Plant Protection of Chinese Academy of Agricultural Sciences
Current assignee: Institute for pesticide control, Ministry of agriculture and rural areas; Institute of Plant Protection of Chinese Academy of Agricultural Sciences
Priority date: 2020-06-22
Filing date: 2020-06-22
Publication date: 2020-09-08
Anticipated expiration: 2040-06-22
Also published as: CN111631213B

Abstract

The invention provides a drug-loaded gel and a preparation method thereof, belonging to the technical field of pesticide preparations. The drug-loaded gel provided by the invention comprises a gel carrier and a water-soluble herbicide loaded on the gel carrier, wherein the gel carrier is network fibers formed by cross-linking folic acid and zinc ions; the loading amount of the water-soluble herbicide in the drug-loaded gel is 0.15-0.36 wt%. The invention takes network fiber formed by crosslinking folic acid and zinc ions as a gel carrier, and can effectively inhibit evaporation and drift of water-soluble herbicide fog drops. The results of the examples of the present invention show that, with water and dicamba-KOH solution as a control, the evaporation inhibition rate of the dicamba-KOH solution is 0% at 35 ℃, while the evaporation inhibition rate of the dicamba gel provided by the present invention is 45.98%, which indicates that the dicamba gel has a significant evaporation inhibition effect; furthermore, the amount of drift of the dicamba gel was significantly lower than that of the dicamba-KOH solution.

Description

Drug-loaded gel and preparation method thereof

Technical Field

The invention relates to the technical field of pesticide preparations, in particular to a drug-loaded gel and a preparation method thereof.

Background

With the rapid development of hardware equipment and a flight control system of the plant protection unmanned aerial vehicle, the spraying uniformity and stability of the plant protection unmanned aerial vehicle are further improved, and the control is more intelligent and simple. However, the development of the matched special pesticide for flight control is lagged, and most of the current plant protection unmanned aerial vehicles are directly sprayed with conventional formulations, so that the problems of pesticide evaporation and drift are outstanding.

Disclosure of Invention

The invention aims to provide a drug-loaded gel and a preparation method thereof, and the drug-loaded gel provided by the invention can effectively inhibit the evaporation and drift of dicamba droplets.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a drug-loaded gel, which comprises a gel carrier and a water-soluble herbicide loaded on the gel carrier, wherein the gel carrier is network fibers formed by cross-linking folic acid and zinc ions; the loading amount of the water-soluble herbicide in the drug-loaded gel is 0.15-0.36 wt%.

Preferably, the content of zinc ions in the drug-loaded gel is 0.09-0.14 wt%.

Preferably, the water-soluble herbicide comprises dicamba, glyphosate, 2, 4D-sodium salt, or methoxone.

The invention provides a preparation method of the drug-loaded gel in the technical scheme, which comprises the following steps:

dissolving folic acid in an alkaline aqueous solution to obtain a folic acid-alkali solution;

dissolving a water-soluble herbicide in the folic acid-alkali solution to obtain the herbicide-folic acid-alkali solution;

and (3) mixing the herbicide-folic acid-alkali solution, zinc nitrate and water in a vortex manner, and standing to obtain the drug-loaded gel.

Preferably, the alkaline substance in the alkaline aqueous solution comprises KOH or NaOH, and the pH value of the folic acid-alkali solution is 10-13.

Preferably, the concentration of folic acid in the folic acid-alkali solution is 0.045-0.055 mol/L.

Preferably, the concentration of the water-soluble herbicide in the herbicide-folic acid-alkali solution is 0.25-0.30 mol/L.

Preferably, the dosage ratio of the zinc nitrate to the water is (0.5-0.6) mmol: 9.4 mL.

Preferably, the rotational speed of the vortex mixing is 1000-8000 rpm, and the time is 20-40 s; the standing time is 0.5-1.5 h.

Preferably, the vortex mixing and the standing are independently carried out at 15-35 ℃.

The invention provides a drug-loaded gel, which comprises a gel carrier and a water-soluble herbicide loaded on the gel carrier, wherein the gel carrier is network fibers formed by cross-linking folic acid and zinc ions; the loading amount of the water-soluble herbicide in the drug-loaded gel is 0.15-0.36 wt%. The network-shaped fiber formed by crosslinking folic acid and zinc ions is used as a gel carrier to load the water-soluble herbicide, so that the particle size of spray droplets of the liquid medicine can be increased, the evaporation and drift of the droplets are effectively inhibited, the utilization rate of pesticides is improved, and the cost is reduced. The results of the examples of the present invention show that, with water and dicamba-KOH solution as a control, the evaporation inhibition rate of the dicamba-KOH solution is 0% at 35 ℃, while the evaporation inhibition rate of the dicamba gel provided by the present invention is 45.98%, which indicates that the dicamba gel has a significant evaporation inhibition effect; furthermore, the amount of drift of the dicamba gel was significantly lower than that of the dicamba-KOH solution.

Drawings

FIG. 1 is a cryo-scanning electron micrograph of dicamba gel prepared in example 1;

FIG. 2 is a graph showing the results of rheological measurements on dicamba gel;

FIG. 3 is a graph showing the results of measuring the wettability of dicamba gel;

FIG. 4 is a layout view of a wind tunnel test device and a mist collection line;

FIG. 5 is a diagram of the droplet size distribution of the spray solution at different locations below the spray head;

FIG. 6 is a chromatogram of dicamba prodrug;

FIG. 7 is a graph showing the results of testing the amount of drift deposition of droplets of dicamba gel and dicamba-KOH solution at different locations using a droplet collection line;

FIG. 8 is a layout view of a wind tunnel test device and a fog droplet collecting card;

FIG. 9 is a graph showing the results of testing the amount of drift deposition of droplets from different positions using a droplet collection card to collect dicamba gel and a dicamba-KOH solution.

Detailed Description

The invention provides a drug-loaded gel, which comprises a gel carrier and a water-soluble herbicide loaded on the gel carrier, wherein the gel carrier is network fibers formed by cross-linking folic acid and zinc ions; the loading amount of the water-soluble herbicide in the drug-loaded gel is 0.15-0.36 wt%, and preferably 0.25-0.36 wt%. In the invention, the content of zinc ions in the drug-loaded gel is preferably 0.09-0.14 wt%, and preferably 0.10-0.12 wt%. In the present invention, the water-soluble herbicide preferably comprises dicamba, glyphosate, 2, 4D-sodium salt or methoxone; in the embodiment of the invention, dicamba is specifically taken as an example to illustrate the structure and performance of the drug-loaded gel provided by the invention.

In the invention, the pterin ring on folic acid tends to form tetramer through hydrogen bond, the tetramer can form nano-fiber through pi-pi accumulation, zinc ions crosslink the nano-fiber into fiber with larger size, and further crosslink to form fiber network with regularly arranged porous structure; the network-shaped fiber formed by crosslinking folic acid and zinc ions is used as a gel carrier, so that the particle size of the spray droplets of the liquid medicine can be increased, the evaporation and drift of the droplets can be effectively inhibited, the utilization rate of pesticides can be improved, and the cost can be reduced.

The folic acid is dissolved in an alkaline aqueous solution to obtain a folic acid-alkali solution. In the invention, the alkaline substance in the alkaline aqueous solution preferably comprises KOH or NaOH, and the pH value of the folic acid-alkali solution is preferably 10-13; the concentration of folic acid in the folic acid-alkali solution is preferably 0.045-0.055 mol/L, and more preferably 0.05 mol/L. In the invention, the concentration of the alkaline substance in the alkaline aqueous solution is preferably 0.45-0.55 mol/L, more preferably 0.5mol/L, and the alkaline aqueous solution with the concentration can ensure that the pH value of the folic acid-alkali solution is within the range of 10-13, which is beneficial to ensuring the full dissolution of folic acid. The method for dissolving folic acid in the alkaline aqueous solution is not particularly limited, and the folic acid and the alkaline aqueous solution are directly mixed to fully dissolve folic acid.

After the folic acid-alkali solution is obtained, the water-soluble herbicide is dissolved in the folic acid-alkali solution to obtain the herbicide-folic acid-alkali solution. In the invention, the concentration of the water-soluble herbicide in the herbicide-folic acid-alkali solution is preferably 0.25-0.30 mol/L, and more preferably 0.27 mol/L. The mode of dissolving the water-soluble herbicide in the folic acid-alkali solution is not particularly limited, and an ultrasonic mixing mode can be specifically adopted.

After the herbicide-folic acid-alkali solution is obtained, the herbicide-folic acid-alkali solution, zinc nitrate and water are mixed in a vortex mode and then stand to obtain the drug-loaded gel. In the invention, the dosage ratio of the zinc nitrate to the water is preferably (0.5-0.6) mmol: 9.4mL, more preferably 0.54 mmol: 9.4 mL. According to the invention, zinc nitrate is preferably dissolved in a portion of the water to obtain a zinc nitrate solution, and the zinc nitrate solution, the remaining water and the herbicide-folic acid-alkali solution are then mixed by vortexing. In the invention, the concentration of the zinc nitrate solution is preferably 0.08-0.12 mol/L, and more preferably 0.1 mol/L.

In the invention, the rotation speed of the vortex mixing is preferably 1000-8000 rpm, and more preferably 5000-8000 rpm; the time is preferably 20 to 40s, and more preferably 30 s. In the invention, the standing time is preferably 0.5-1.5 h, and more preferably 1 h. In the invention, the vortex mixing and the standing are preferably independently carried out at 15-35 ℃, more preferably independently carried out at 20-30 ℃, and particularly can be carried out at room temperature, i.e. no additional heating or cooling is needed; in the examples of the present invention, vortex mixing and standing were carried out specifically at 25 ℃.

In the invention, during the standing process, the system gradually forms uniform and transparent gel; the invention preferably controls the content of each component in the range, can load the water-soluble herbicide into a hydrogel system formed by crosslinking folic acid and zinc ions, and is favorable for forming drug-loaded gel with stable performance.

The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The test plants and test reagents used in the examples were as follows:

test plants: chenopodium album, an annual herbaceous plant, commonly found in roadsides, wastelands and fields, is a difficult weed to remove. The chenopodium quinoa seeds used for the experiment are provided by plant protection research institute of Chinese academy of agricultural sciences, and are firstly soaked in gibberellic acid solution (with the concentration of 0.1 wt%) for 24 hours to break seed dormancy, then the seeds are sowed in flowerpots, 3-5 seeds are sowed in each flowerpot, and the seeds are cultured in a greenhouse. The greenhouse culture conditions are controlled as follows: photoperiod 14 h; the relative humidity is 65-80%; the day and night temperatures were 33 ℃ and 26 ℃ respectively.

Test reagents: 97% Dicamba (Dicamba) crude drug, purchased from Jiangsu Changqing agro-chemical GmbH; folic acid hydrate (C)₁₉H₁₉N₇O₆·xH₂O) purity of>98 percent of the total weight of the product, purchased from Taishiai (Shanghai) chemical industry development Limited company; potassium hydroxide (KOH), purity>85% of the total weight of the composition, purchased from Guangzhou Kogyo, Tianjin; zinc nitrate hydrate (Zn (NO)₃)₂·xH₂O) purity of 98% from alatin reagent company; the experimental water is ultrapure water.

Example 1

Dissolving 10mmol of KOH in 20mL of water to obtain KOH aqueous solution; dissolving 1mmol of folic acid hydrate in the KOH aqueous solution to obtain a clear and transparent folic acid-KOH solution; mixing 5.4mmol of dicamba with a folic acid-KOH solution, and carrying out ultrasonic treatment until the dicamba is completely dissolved to obtain a dicamba-folic acid-KOH solution;

0.6mL of dicamba-folic acid-KOH solution, 0.54mL of 0.1mol/L zinc nitrate aqueous solution and 8.86mL of water are mixed, and the mixture is vortexed at room temperature (25 ℃) and 8000rpm for 30s and then is kept stand for 1h to obtain dicamba gel (namely the dicamba-loaded folic acid/zinc nitrate hydrogel).

Comparative example

Control 1 was dicamba-KOH solution: the dicamba-containing aqueous solution is obtained by mixing dicamba and a KOH aqueous solution, wherein the concentration of the dicamba is 3.6g/L, and the concentration of the KOH is 1.68 g/L;

control 2 was water.

Characterization and Performance testing

And (3) characterization: the microstructure of dicamba gel is observed by using a Cryo-scanning electron microscope (Cryo-SEM), a scanning electron microscope Cryo-transmission system (QuorumPP 3010T in British) is combined with a Hitachi cold field emission scanning electron microscope SU8010, a sample is frozen and fixed in liquid nitrogen mud, the sample is broken under a vacuum low-temperature environment and then sublimated under a vacuum-75 ℃ condition, and the sample is placed on a cold table of the scanning electron microscope for observation through the Cryo-transmission system after the frozen sample preparation is completed.

FIG. 1 is a cryo-SEM of the dicamba gel prepared in example 1, wherein a and b are cryo-SEM at 1.00k and 2.50k magnifications, respectively. As can be seen from fig. 1, the lyophilized dicamba gel has a regularly arranged porous structure, and is connected by a scaffold formed by nanofibers. This is related to the specific structure of the folate molecule, specifically, the pterin ring on folic acid tends to form tetramers through hydrogen bonding, the tetramers can form nanofibers through pi-pi stacking, and zinc ions crosslink the nanofibers into larger size fibers, which are further crosslinked to form a fiber network.

The dicamba gel provided by the invention has a pore structure with larger pore diameter and a slightly loose structure, so that the dicamba gel is more favorable for atomizing the drug-loaded gel into fog drops by a spraying device, and the situation that the spray head is blocked by liquid medicine due to too high system viscosity is avoided.

And (3) performance testing:

1 rheological Properties

A small piece of dicamba gel was taken with a small spoon and placed on the sample stage of a physica MCR301 rheometer with a PP50 rotor as the rotor, 25mm flat holder and 1mm measuring distance. Carrying out dynamic stress scanning in a stress range mode with the frequency of 1Hz and the pressure of 0.1-10 Pa; carrying out dynamic frequency scanning in a frequency range mode with stress of 1Pa and 0.1-10 Hz; controlling the shear rate from 0.1s^-1Increased to 10s^-1Then again from 10s^-1Reduced to 0.1s^-1Measuring the change of the dicamba gel viscosity along with the shear rate through a continuous flow experiment; four cycles of continuous strain step measurements were performed at a frequency of 1Hz, 0.8% strain for 60s, and 80% strain for 30s to determine the shear thinning and self-healing properties of dicamba gel. All the above tests were carried out at 25 ℃.

FIG. 2 is a graph showing the results of rheological measurements on dicamba gels. In FIG. 2, a is a pressure scan of dicamba gel at a fixed frequency of 1Hz, resulting in a range of linear viscoelastic regions; the results show that the dicamba gel can withstand a maximum stress around 10 Pa. B in FIG. 2 is a frequency scan of dicamba gel at a fixed stress of 1 Pa; the results show the storage modulusThe (elastic modulus, G ') and the loss modulus (viscous modulus, G') are substantially independent of the frequency (f), whereas G 'is an order of magnitude larger than G' over the entire frequency range studied. C in fig. 2 is a test result of the continuous flow experiment, and d in fig. 2 is a test result of the continuous strain step measurement experiment; the experimental results show that the shear rate is from 0.1s^-1Increased to 10s^-1When the viscosity of the dicamba gel became small, the shear rate was subsequently varied from 10s^-1Reduced to 0.1s^-1The viscosity of the dicamba gel increased again to the initial value; the dicamba gel was subjected to step measurements of alternately high strain at 80% and low strain at 0.8%, the structure of the dicamba gel was destroyed under high strain and then returned to the original state under low strain, and multiple cycles of measurements were performed with the results consistent. This demonstrates that the dicamba gel provided by the present invention has shear thinning and self-healing properties within an acceptable range. The drug-loaded gel provided by the invention has the characteristics of shear self-repair, the drug-loaded gel cannot be influenced by the shear force during spray atomization, atomized fog drops can still keep higher viscosity, and the crosslinked nano fibers in the fog drops cannot be influenced, so that a better spraying effect is ensured.

2 wetting Property

The contact angles of dicamba gel, dicamba-KOH solution and water on chenopodium quinoa leaves were determined by the sitting-drop method at 25 ℃ using a contact angle measuring instrument OCA20(DataPhysics, germany). Selecting a growing chenopodium quinoa plant, carefully washing leaves with consistent sizes under water flow to remove surface dust, airing to be dry, sticking the leaves on a glass slide by using a double-sided adhesive tape, putting the glass slide into a constant-temperature sample tank, setting a program to enable an injector to automatically inject 4 mu L of liquid drops on the chenopodium quinoa leaves, quickly shooting a picture by using a CCD (charge coupled device) camera and transmitting the picture to a computer, and determining the value of a contact angle by using an L-Y method (Laplace-Young).

The adhesion of dicamba gel droplets to chenopodium quinoa leaves was determined by using a DCAT 21 surface tensiometer with a high sensitivity micro-electromechanical balancing system. The slide with attached chenopodium quinoa leaves was placed on a balance stage, a drop (about 10 μ L) was injected with a micro-syringe and suspended on a metal ring, and then the balance stage was moved upward at a constant speed of 0.01mm/s until the chenopodium quinoa leaves contacted the drop. The instrument starts to measure, and when the measurement is finished, the platform automatically descends at the same speed until the liquid drops are separated from the chenopodium album leaves. The software automatically records the relationship curve of the adhesion force and the distance of the liquid drop just contacting and separating from the surface of the chenopodium album leaf, and the peak data recorded by the curve is the maximum adhesion force value.

Each set of samples was measured at least five times per experiment and finally averaged.

Fig. 3 is a graph showing the results of measuring the wetting properties of dicamba gel, wherein a is the results of measuring the surface tensions of dicamba gel, dicamba-KOH solution and water, b is the results of measuring the contact angles of dicamba gel, dicamba-KOH solution and water on chenopodium quinoa leaves, c is the maximum value of the adhesion between dicamba gel, dicamba-KOH solution and droplets of water and the surfaces of chenopodium quinoa leaves, and d is the adhesion-distance curve of dicamba gel, dicamba-KOH solution and droplets of water and the surfaces of chenopodium quinoa leaves. As can be seen from a and b in FIG. 3, the surface tension and contact angle of dicamba gel, dicamba-KOH solution and water are not very different; as can be seen from c and d in fig. 3, the adhesion of the droplets of dicamba gel and dicamba-KOH solution to the surface of the chenopodium album leaves is better than that of water, and the adhesion of the droplets of dicamba gel and dicamba-KOH solution to the surface of the chenopodium album leaves is not much different.

3 Evaporation performance

The evaporation performance of dicamba gel and dicamba-KOH solution was measured by the hanging drop method at 35 ℃ using a contact angle measuring instrument OCA 20. Specifically, a program is set in a constant-temperature sample tank, an injector automatically injects about 9 mu L of liquid drops, a video optical system shoots the state of the liquid drops and transmits the state to a computer, the change condition of the volume of the liquid drops along with time within 1min is recorded by using an L-Y method (Laplace-Young), and the evaporation inhibition rate is calculated. The evaporation inhibition rate calculation formula is as follows:

R＝100％×(V0-Vi)/V0；

wherein, R: evaporation inhibition rate; v0: difference of volume change of pure water droplets within 1 min; and Vi: the drop of the sample was tested for the difference in volume change over 1 min.

The experimental result shows that the evaporation inhibition rate of the dicamba-KOH solution is 0% and the evaporation inhibition rate of the dicamba gel is 45.98% under the condition of 35 ℃, which indicates that the dicamba gel has obvious evaporation inhibition effect.

4 drift property

The test wind tunnel is located in a droplet space operation and dose transfer laboratory of university of large-scale courseware. The length of the wind tunnel working segment is 5m, the height is 1m, and the width is 2m (as shown in fig. 4 and 8). The droplet drift characteristics of dicamba gel and dicamba-KOH solution were compared under the same spray conditions and the experiment was performed in two sets, each set being repeated three times. The spray head for testing is a hollow conical atomization spray head TR005, and the spray head is 0.7m away from the ground. The test temperature was 20 ℃ and the relative humidity was 40%.

4.1 droplet size test: a hollow cone atomizing nozzle TR005 is used, mist drops 20cm, 30cm, 40cm and 50cm away from the lower part of the nozzle are collected by a Winner 318C laser mist drop particle size analyzer, the particle size of the mist drops atomized by the nozzle is analyzed, the analyzer needs to be debugged before testing, the spraying pressure is 0.3Mpa, and the height of the nozzle from the ground is 1.0 m.

Droplet size test results: the correlated relation of biological-optimum grain size exists between the grain size of fog drops and the pesticide effect. Related researches of pesticide spraying technical theory consider that thicker and larger fog drops of 100-300 mu m are suitable for spraying herbicide. Therefore, in order to investigate the atomization performance of dicamba gel, the present inventors compared it with an aqueous dicamba-KOH solution and measured the atomized particle size distribution at different positions (20cm, 30cm, 40cm, 50cm) below the spray head, and the results are shown in table 1.

TABLE 1 droplet size distribution of spray solution at different positions below the spray head

Note: v10 indicates that the volume percentage of the droplets smaller than the particle size is 10%; v50 indicates that the volume percentage of the droplets smaller than the particle size is 50%; v90 indicates that the volume percentage of the droplets having a particle size smaller than this is 90%. VAD represents the average particle size of the droplets.

As can be seen from table 1, the droplet size of both the dicamba-KOH solution and the dicamba gel increased with increasing distance from the spray head; comparing the droplet size of water, dicamba-KOH solution and dicamba gel at the same distance, the droplet size of dicamba gel was the largest, the water order, and finally the dicamba-KOH solution. In order to highlight the difference between the particle sizes of the spray droplets of the dicamba-KOH solution and the dicamba gel more visually and vividly, the particle sizes of the droplets at different positions are used for drawing to obtain a graph 5. In fig. 5, a to d are the distribution diagrams of the droplet size at 20cm, 30cm, 40cm and 50cm from the nozzle, respectively, and it can be seen from fig. 5 and table 1 that dicamba gel can improve the droplet size distribution and increase the droplet size.

4.2 droplet collection line (polyethylene rope) collection droplet drift deposition test: polyethylene ropes were placed on a plane perpendicular to the direction of the air flow at 2m downwind from the spray head to collect airborne mist droplets (see figure 4). And 6 polyethylene ropes (marked as V1-V6) are vertically arranged from top to bottom at a spacing of 0.1m, wherein V1 is 0.1m away from the ground. One more polyethylene rope (marked as H1-H5) is arranged at a distance of 2.0m, 2.5m, 3.0m, 3.5m and 4.0m from the spray head in the horizontal direction respectively, the polyethylene ropes are used for collecting the fog drops drifting in the horizontal direction and are all 0.1m from the ground height, and the first polyethylene rope in the vertical direction is also the first polyethylene rope in the horizontal direction (namely H1 is V1). The polyethylene ropes are 2.0m in length and 2.0mm in diameter. The spraying pressure is 0.3Mpa, the wind speed is fixed at 2m/s, and the spraying time is 10 s.

Sample treatment: after the test is finished, each polyethylene rope is separately packed in a self-sealing bag, 10mL of water is added into each self-sealing bag, after the self-sealing bags are sealed, the liquid medicine is eluted by ultrasonic waves for 30min, the self-sealing bags are inverted for a plurality of times, so that the eluent completely immerses the collecting ropes to fully soak the collecting ropesEluting the fog drops collected on the collecting rope for 30min, sampling 1mL of the fog drops per bag, passing through a 0.22 mu m water system filter membrane to a sample injection vial for waiting analysis, wherein the liquid phase detection condition of dicamba is that a DAD detector detects the wavelength of 254nm, a chromatographic column eclipsplus C18 column (5 mu m × 4.6.6 mm × 150mm), the mobile phase is acetonitrile, the volume fraction of formic acid is 0.3 percent and 60: 40, the flow rate of the mobile phase is 1mL/min, a column box is 30 ℃, the sample injection volume is 5 mu L, and the quantitative analysis is carried out by adopting an external standard method, the volume fraction of the dicamba raw drug chromatogram is shown in figure 6, and the linear relation between the peak area (y) and the mass concentration (x) is 19.253x +5.2879, R is R25 x +5.2879, and the linear relation between the peak area (y) and the mass concentration (x) is 0.25-²＝99.6％。

The polyethylene rope collects the testing result of the drifting deposition amount of the fogdrop: fig. 7 is a graph showing the results of testing the drift deposition amount of dicamba gel and dicamba-KOH solution at different positions on a vertical plane and a horizontal plane, respectively, using a droplet collecting line to collect the drift deposition amount of dicamba gel and dicamba-KOH solution. From FIG. 7, it can be seen that the amount of drift of the dicamba gel was significantly lower than that of the dicamba-KOH solution.

4.3 fog drop collecting card (water sensitive paper) collecting drifting fog drop test: the water-sensitive paper is arranged at a distance of 2.0m, 2.5m, 3.0m, 3.5m and 4.0m from the nozzle in the horizontal direction at a distance of 2m from the downwind direction of the nozzle, and three pieces of water-sensitive paper are arranged at each position at a distance of 0.1m from top to bottom (as shown in figure 8). The spraying pressure is 0.3Mpa, the wind speed is fixed at 2m/s, the wind tunnel condition is 20 ℃/RH 40%, and the spraying time is 5 s.

The test result of collecting the drifting fog drops by the water-sensitive paper is as follows: the water sensitive paper is a high-sensitivity professional test paper. When the spray mist of the plant protection unmanned aerial vehicle falls on the surface of the plant protection unmanned aerial vehicle, blue spots are generated immediately, and during field spraying, the water-sensitive paper can be used for measuring the distribution, density and coverage of the mist droplets, and can also be used for evaluating the spraying quality of a spraying machine and measuring the spraying drift. In order to further determine the drift resistance of dicamba gel, water-sensitive paper was arranged at different horizontal positions and heights (i.e., vertical positions) for testing, specifically, the Deposit Scan software was used to Scan the water-sensitive paper to obtain information about the fog drops on the water-sensitive paper, including fog drop density, fog drop coverage, and the like, and the fog drop coverage was analyzed by Origin mapping, and the result is shown in fig. 9. In FIG. 9, a is the statistical result of the coverage rate of the mist droplets on the water-sensitive paper arranged at the positions of 0.1m height from the ground and 2.0m, 2.5m, 3.0m, 3.5m and 4.0m distance from the spray head in the horizontal position; b is the statistical result of the covering rate of the fog drops on the water-sensitive paper which is arranged at the position 0.3m away from the ground and 2.0m, 2.5m, 3.0m, 3.5m and 4.0m away from the spray head on the horizontal position; c is the statistical result of the covering rate of the fog drops on the water-sensitive paper which is arranged at the position 0.5m away from the ground and 2.0m, 2.5m, 3.0m, 3.5m and 4.0m away from the spray head on the horizontal position; and d is an electronic image of the water-sensitive paper arranged at different spatial positions in the corresponding figure 8 after being scanned by the Deposit Scan software. As shown in a, b and c of fig. 9, the coverage of the droplets is the largest at a height of 0.5m from the ground in the vertical position and the coverage of the droplets is the largest at a position of 2.0m from the spray head in the horizontal position; the deposition of droplets of dicamba-KOH solution and dicamba gel on water-sensitive paper at different spatial locations can be obtained more intuitively from d in fig. 9. The drifting fog drops are collected by combining the fog drop collecting ropes of the wind tunnel test and the results of the deposition experiment of the fog drops at different spatial positions are observed by using the water-sensitive paper, as shown in fig. 7 and 9, the drift amount of the dicamba gel is obviously lower than that of the dicamba-KOH solution.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. The drug-loaded gel comprises a gel carrier and a water-soluble herbicide loaded on the gel carrier, wherein the gel carrier is network-shaped fibers formed by cross-linking folic acid and zinc ions; the loading amount of the water-soluble herbicide in the drug-loaded gel is 0.15-0.36 wt%.

2. The drug-loaded gel of claim 1, wherein the content of zinc ions in the drug-loaded gel is 0.09-0.14 wt%.

3. The drug loaded gel of claim 1 or 2, wherein the water soluble herbicide comprises dicamba, glyphosate, 2, 4D-sodium salt or methoxone.

4. The preparation method of the drug-loaded gel of any one of claims 1 to 3, which is characterized by comprising the following steps:

5. The method according to claim 4, wherein the alkaline substance in the alkaline aqueous solution comprises KOH or NaOH, and the pH of the folic acid-alkali solution is 10 to 13.

6. The preparation method according to claim 5, wherein the concentration of folic acid in the folic-acid alkali solution is 0.045-0.055 mol/L.

7. The method according to claim 6, wherein the concentration of the water-soluble herbicide in the herbicide-folic acid-alkali solution is 0.25 to 0.30 mol/L.

8. The preparation method according to claim 4, wherein the ratio of the zinc nitrate to the water is (0.5-0.6) mmol: 9.4 mL.

9. The method of claim 4, wherein the vortex mixing is performed at a speed of 1000 to 8000rpm for 20 to 40 seconds; the standing time is 0.5-1.5 h.

10. The method of claim 4 or 9, wherein the vortex mixing and the standing are independently performed at 15 to 35 ℃.