CN117426377B - Preparation method of pesticide loaded gel with environment response controlled release - Google Patents
Preparation method of pesticide loaded gel with environment response controlled release Download PDFInfo
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- CN117426377B CN117426377B CN202210814418.0A CN202210814418A CN117426377B CN 117426377 B CN117426377 B CN 117426377B CN 202210814418 A CN202210814418 A CN 202210814418A CN 117426377 B CN117426377 B CN 117426377B
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- polyglutamic acid
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- 239000000575 pesticide Substances 0.000 title claims abstract description 61
- 238000002360 preparation method Methods 0.000 title claims abstract description 24
- 238000013270 controlled release Methods 0.000 title claims abstract description 9
- 230000004044 response Effects 0.000 title abstract description 11
- 229920002643 polyglutamic acid Polymers 0.000 claims abstract description 41
- 229920002134 Carboxymethyl cellulose Polymers 0.000 claims abstract description 29
- 239000001768 carboxy methyl cellulose Substances 0.000 claims abstract description 29
- 235000010948 carboxy methyl cellulose Nutrition 0.000 claims abstract description 29
- 239000008112 carboxymethyl-cellulose Substances 0.000 claims abstract description 29
- 239000000440 bentonite Substances 0.000 claims abstract description 24
- 229910000278 bentonite Inorganic materials 0.000 claims abstract description 24
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 claims abstract description 24
- 239000000243 solution Substances 0.000 claims description 41
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 38
- 239000007863 gel particle Substances 0.000 claims description 34
- 239000005941 Thiamethoxam Substances 0.000 claims description 32
- NWWZPOKUUAIXIW-FLIBITNWSA-N thiamethoxam Chemical compound [O-][N+](=O)\N=C/1N(C)COCN\1CC1=CN=C(Cl)S1 NWWZPOKUUAIXIW-FLIBITNWSA-N 0.000 claims description 32
- VTNQPKFIQCLBDU-UHFFFAOYSA-N Acetochlor Chemical compound CCOCN(C(=O)CCl)C1=C(C)C=CC=C1CC VTNQPKFIQCLBDU-UHFFFAOYSA-N 0.000 claims description 26
- 239000005730 Azoxystrobin Substances 0.000 claims description 23
- 239000004480 active ingredient Substances 0.000 claims description 23
- WFDXOXNFNRHQEC-GHRIWEEISA-N azoxystrobin Chemical compound CO\C=C(\C(=O)OC)C1=CC=CC=C1OC1=CC(OC=2C(=CC=CC=2)C#N)=NC=N1 WFDXOXNFNRHQEC-GHRIWEEISA-N 0.000 claims description 23
- 239000011259 mixed solution Substances 0.000 claims description 23
- 238000003756 stirring Methods 0.000 claims description 22
- 238000006243 chemical reaction Methods 0.000 claims description 20
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 claims description 19
- 238000001035 drying Methods 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 11
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 10
- 235000010482 polyoxyethylene sorbitan monooleate Nutrition 0.000 claims description 10
- 229920000053 polysorbate 80 Polymers 0.000 claims description 10
- 239000008367 deionised water Substances 0.000 claims description 9
- 229910021641 deionized water Inorganic materials 0.000 claims description 9
- 238000005406 washing Methods 0.000 claims description 8
- 239000003960 organic solvent Substances 0.000 claims description 4
- 108700022290 poly(gamma-glutamic acid) Proteins 0.000 claims description 4
- 238000005119 centrifugation Methods 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 2
- 239000012868 active agrochemical ingredient Substances 0.000 claims 2
- 230000000361 pesticidal effect Effects 0.000 claims 1
- 230000007613 environmental effect Effects 0.000 abstract description 9
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 abstract description 4
- 239000002994 raw material Substances 0.000 abstract description 3
- 239000002253 acid Substances 0.000 abstract description 2
- 229910021645 metal ion Inorganic materials 0.000 abstract description 2
- 239000002861 polymer material Substances 0.000 abstract description 2
- 230000004043 responsiveness Effects 0.000 abstract description 2
- 238000001179 sorption measurement Methods 0.000 abstract description 2
- 230000015556 catabolic process Effects 0.000 abstract 1
- 230000009920 chelation Effects 0.000 abstract 1
- 238000006731 degradation reaction Methods 0.000 abstract 1
- 150000004676 glycans Chemical class 0.000 abstract 1
- 229920001282 polysaccharide Polymers 0.000 abstract 1
- 239000005017 polysaccharide Substances 0.000 abstract 1
- 239000000499 gel Substances 0.000 description 88
- 239000003814 drug Substances 0.000 description 22
- 229940079593 drug Drugs 0.000 description 20
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 description 15
- 230000008961 swelling Effects 0.000 description 12
- 230000000694 effects Effects 0.000 description 11
- 238000005538 encapsulation Methods 0.000 description 9
- 108010020346 Polyglutamic Acid Proteins 0.000 description 8
- 238000011068 loading method Methods 0.000 description 8
- 238000004128 high performance liquid chromatography Methods 0.000 description 7
- 239000004562 water dispersible granule Substances 0.000 description 7
- 239000000969 carrier Substances 0.000 description 6
- 238000000502 dialysis Methods 0.000 description 6
- 239000000017 hydrogel Substances 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- WHUUTDBJXJRKMK-GSVOUGTGSA-N D-glutamic acid Chemical compound OC(=O)[C@H](N)CCC(O)=O WHUUTDBJXJRKMK-GSVOUGTGSA-N 0.000 description 5
- 238000004090 dissolution Methods 0.000 description 5
- 238000001514 detection method Methods 0.000 description 4
- 239000012528 membrane Substances 0.000 description 4
- 244000005700 microbiome Species 0.000 description 4
- 229920005615 natural polymer Polymers 0.000 description 4
- 229920000642 polymer Polymers 0.000 description 4
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical group OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 241000607479 Yersinia pestis Species 0.000 description 3
- 230000001186 cumulative effect Effects 0.000 description 3
- 239000003995 emulsifying agent Substances 0.000 description 3
- 229960002989 glutamic acid Drugs 0.000 description 3
- 239000008187 granular material Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 3
- 229910052753 mercury Inorganic materials 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 239000008363 phosphate buffer Substances 0.000 description 3
- 239000010453 quartz Substances 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- 229930182847 D-glutamic acid Natural products 0.000 description 2
- WHUUTDBJXJRKMK-VKHMYHEASA-N L-Glutamic acid Natural products OC(=O)[C@@H](N)CCC(O)=O WHUUTDBJXJRKMK-VKHMYHEASA-N 0.000 description 2
- 125000000129 anionic group Chemical group 0.000 description 2
- 239000002775 capsule Substances 0.000 description 2
- 229920002678 cellulose Polymers 0.000 description 2
- 239000001913 cellulose Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 201000010099 disease Diseases 0.000 description 2
- 208000037265 diseases, disorders, signs and symptoms Diseases 0.000 description 2
- 239000000178 monomer Substances 0.000 description 2
- 238000001782 photodegradation Methods 0.000 description 2
- 229920001184 polypeptide Polymers 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 108090000765 processed proteins & peptides Proteins 0.000 description 2
- 102000004196 processed proteins & peptides Human genes 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 239000002689 soil Substances 0.000 description 2
- WHUUTDBJXJRKMK-UHFFFAOYSA-N Glutamic acid Natural products OC(=O)C(N)CCC(O)=O WHUUTDBJXJRKMK-UHFFFAOYSA-N 0.000 description 1
- 241001465754 Metazoa Species 0.000 description 1
- 206010051246 Photodermatosis Diseases 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006065 biodegradation reaction Methods 0.000 description 1
- 239000012876 carrier material Substances 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 235000013922 glutamic acid Nutrition 0.000 description 1
- 239000004220 glutamic acid Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 230000002262 irrigation Effects 0.000 description 1
- 238000003973 irrigation Methods 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000000447 pesticide residue Substances 0.000 description 1
- 230000008845 photoaging Effects 0.000 description 1
- 238000006303 photolysis reaction Methods 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000013112 stability test Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
- A01N25/00—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
- A01N25/08—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests containing solids as carriers or diluents
- A01N25/10—Macromolecular compounds
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
- A01N25/00—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
- A01N25/32—Ingredients for reducing the noxious effect of the active substances to organisms other than pests, e.g. toxicity reducing compositions, self-destructing compositions
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
- A01N37/00—Biocides, pest repellants or attractants, or plant growth regulators containing organic compounds containing a carbon atom having three bonds to hetero atoms with at the most two bonds to halogen, e.g. carboxylic acids
- A01N37/18—Biocides, pest repellants or attractants, or plant growth regulators containing organic compounds containing a carbon atom having three bonds to hetero atoms with at the most two bonds to halogen, e.g. carboxylic acids containing the group —CO—N<, e.g. carboxylic acid amides or imides; Thio analogues thereof
- A01N37/26—Biocides, pest repellants or attractants, or plant growth regulators containing organic compounds containing a carbon atom having three bonds to hetero atoms with at the most two bonds to halogen, e.g. carboxylic acids containing the group —CO—N<, e.g. carboxylic acid amides or imides; Thio analogues thereof containing the group; Thio analogues thereof
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
- A01N43/00—Biocides, pest repellants or attractants, or plant growth regulators containing heterocyclic compounds
- A01N43/48—Biocides, pest repellants or attractants, or plant growth regulators containing heterocyclic compounds having rings with two nitrogen atoms as the only ring hetero atoms
- A01N43/54—1,3-Diazines; Hydrogenated 1,3-diazines
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
- A01N51/00—Biocides, pest repellants or attractants, or plant growth regulators containing organic compounds having the sequences of atoms O—N—S, X—O—S, N—N—S, O—N—N or O-halogen, regardless of the number of bonds each atom has and with no atom of these sequences forming part of a heterocyclic ring
Landscapes
- Life Sciences & Earth Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Health & Medical Sciences (AREA)
- Wood Science & Technology (AREA)
- Pest Control & Pesticides (AREA)
- Plant Pathology (AREA)
- Engineering & Computer Science (AREA)
- Dentistry (AREA)
- Agronomy & Crop Science (AREA)
- Zoology (AREA)
- Environmental Sciences (AREA)
- Toxicology (AREA)
- Agricultural Chemicals And Associated Chemicals (AREA)
Abstract
The invention discloses a preparation method of pesticide loaded gel with environment response controlled release, the main raw materials of the gel are gamma-polyglutamic acid and carboxymethyl cellulose, the gel is formed by utilizing chelation of carboxyl and metal ions, and a proper amount of bentonite is added into the gel to further enhance adsorption capacity, so that the influence on pesticide effectiveness due to over-fast degradation of the gel is avoided. The invention utilizes the conformational change of polyamino acid and polysaccharide polymer materials in different environments to endow the gel with environmental responsiveness, so that the release rate of pesticides in the gel can be changed along with the change of pH and temperature, and the light instability of pesticides can be effectively relieved, therefore, the gel carrier prepared by the invention has very wide application prospect and potential social and economic values.
Description
Technical Field
The invention relates to the technical field of agriculture, in particular to a preparation method of pesticide loaded gel with environment response controlled release.
Background
In the using process of the pesticide, the pesticide can drift, bounce, leaching and other phenomena due to the influence of environmental conditions, interfacial properties, the level of the pesticide application apparatus and the like, so that the pesticide utilization rate is reduced. The total amount of pesticides used worldwide is nearly 600 tens of thousands of tons each year, but the use efficiency of these pesticides is less than 40%, and more than 60% of the pesticide solution rolls into the surrounding environment by irrigation, spraying, leaf spring or rain wash. And the concentration of the active ingredients is rapidly reduced due to the effects of hydrolysis, photodecomposition or biodegradation after the preparation is sprayed, and the utilization rate of the preparation on harmful animals and plants is less than 0.1%, so that the ideal control effect can be achieved only by repeated application of the preparation. The considerable waste of substances is caused, and meanwhile, the pesticide residue in the whole ecological system is increased, so that the pollution of water, soil and atmosphere is caused, and the ecological environment is destroyed. The pesticide slow-release granule can enable the active ingredient to be released into the environment at a slow or controllable rate, thereby realizing the pest control while reducing the use amount of the pesticide, reducing the toxicity to non-target organisms and reducing the environmental load.
Polyglutamic acid (gamma-PGA) is an anionic polypeptide polymer polymerized by microorganisms through gamma-amide bonds by using L-glutamic acid and D-glutamic acid monomers, and is a protective capsule secreted by partial microorganisms. In recent years, the research shows that the polyglutamic acid hydrogel has the characteristics of good hydrophilicity, high swelling rate, good biocompatibility, biodegradability and the like, and can also effectively shield light radiation and relieve light aging. Therefore, polyglutamic acid is expected to be used as a main material of pesticide slow release gel to reduce photodegradation of pesticide in practical application.
Cellulose and its derivatives (such as carboxymethyl cellulose) are a large class of renewable natural polymer materials, have good biodegradability, are rich in resources, various in types and low in price, and have been widely applied to the pesticide slow release field. Carboxymethyl cellulose is a derivative generated by cellulose through carboxymethylation reaction, contains a large number of hydroxyl groups and carboxyl groups, and can be crosslinked with a plurality of metal ions to form hydrogel. The gel prepared by taking the carboxymethyl cellulose as the raw material has good hydrophilicity, high swelling rate, good biocompatibility and biodegradability. However, the release rate of the granular pesticide taking the carboxymethyl cellulose as a carrier is too high, the long-term disease and pest resistance effect of the pesticide is affected, and the gel particles still cannot solve the problems of unstable light, unstable acid and alkali and the like of the pesticide. In addition, the existing granule can only release the active ingredients slowly and continuously, and the carrier material of the granule generally lacks environmental responsiveness and does not have a real controlled release function.
Disclosure of Invention
The invention aims to: in order to solve the technical problems, the invention discloses a preparation method of pesticide loaded gel with environment response controlled release, which comprises the following steps:
(1) Preparation of gel particles: adding bentonite, gamma-polyglutamic acid and carboxymethyl cellulose into deionized water, stirring until the mixture is completely and uniformly mixed to obtain a mixed solution, adding ferric trichloride solution, continuously stirring for reaction, centrifuging, washing and drying the product until the water content is less than or equal to 5%, and obtaining gel particles;
(2) Preparation of pesticide active ingredient solution: adding the pesticide active ingredient into the mixed solution of the water/organic solution dissolved with the Tween 80, and uniformly stirring to obtain a pesticide active ingredient solution;
(3) And (3) preparing the gel loaded with the pesticide active ingredients: adding the gel particles obtained in the step (1) into the pesticide active ingredient solution prepared in the step (2) to react for 0.2-2 hours, and then separating and drying to obtain the pesticide loaded gel, wherein the size of the gel particles is 5-25 mu m.
In one embodiment, in the step (3), the separation and drying are carried out by centrifugally washing the product for several times, and then drying at about 60 ℃ until the water content is less than or equal to 5%, thus obtaining the gel particles.
Wherein in the step (1), bentonite accounts for 2% of the total mass of the mixed solution, gamma-polyglutamic acid accounts for 1-5% of the total mass of the mixed solution, and carboxymethyl cellulose accounts for 1-5% of the total mass of the mixed solution.
The adding amount of the ferric trichloride is 0.1-0.8% of the ferric trichloride in the reaction system by mass percent.
Wherein the gamma-polyglutamic acid is pure gamma-polyglutamic acid or gamma-polyglutamate; wherein the number average molecular weight of the gamma-polyglutamic acid is 1000-3000kDa.
In the step (1), bentonite, gamma-polyglutamic acid and carboxymethyl cellulose are added into deionized water, and then stirred at room temperature for 1000r/min to obtain a mixed solution, and ferric trichloride solution is added, and stirring reaction is continued for 0.5-1h at room temperature.
In the step (1), the product is centrifugally washed for 3-4 times and then dried at 60-80 ℃ until the water content is less than 5%, and gel particles are obtained, wherein the centrifugation condition is 5000-6000rpm, and each time is 10-20min.
Preferably, in the step (2), the pesticide active ingredient is one of thiamethoxam, acetochlor or azoxystrobin, and the good water solubility of the pesticide active ingredient can ensure uniform dispersion in the carrier and can be combined with carboxymethyl cellulose and gamma-polyglutamic acid in the carrier through hydrophilic effect. Other pesticides with better water solubility can also be suitable for the gel carrier.
The content of the pesticide active ingredient in the pesticide active ingredient solution is 2-5mg/mL.
Wherein the organic solvent in the step (2) is ethanol, the volume ratio of water to the organic solvent is 1:1, and the content of tween 80 is 0.4-0.6% of the mass of the mixed solution of water and the organic solution, preferably 0.5%.
The mass ratio of the pesticide active ingredient solution to the gel particles is 10:1-50:1.
The beneficial effects are that: compared with the prior art, the invention has the following advantages:
(1) According to the pesticide-loaded gel disclosed by the invention, carboxymethyl cellulose and polyglutamic acid are used as main materials, and two natural polymers contain a large number of carboxyl groups, so that under an alkaline condition, the two polymers can carry high-density negative charges to generate electrostatic repulsive force, so that the swelling rate of the gel is obviously increased, and the drug release rate is accelerated; and as the temperature decreases, the gel collapses to form a compact structure of hard particles, limiting pesticide release. Therefore, the pesticide loaded gel disclosed by the invention is an intelligent gel carrier capable of responding to environmental factors such as pH, temperature and the like and combining active triggering control release and passive slow release;
(2) Polyglutamic acid (gamma-PGA) is an anionic polypeptide polymer formed by polymerizing L-glutamic acid and D-glutamic acid monomers through gamma-amide bonds by microorganisms, is a protective capsule secreted by partial microorganisms, and has been found in recent years that polyglutamic acid hydrogel has the characteristics of good hydrophilicity, high swelling rate, good biocompatibility, biodegradability and the like, and can also effectively shield light radiation and relieve photoaging. Therefore, the polyglutamic acid serving as a main material of the pesticide slow-release gel can effectively reduce the photodegradation of the pesticide, so that the application effect of the pesticide is improved. In addition, the carrier has wide and easily available sources of raw materials, the process is simple, the operability is strong, the comprehensive utilization cost is low, and the carrier is a pollution-free and environment-friendly product;
(3) The natural polymer gel has the advantages of good hydrophilicity, high swelling rate and biodegradability, but the drug release rate in the gel is too high, so that the long-acting disease and pest resistance effect of the pesticide is affected. The bentonite has the advantages of rich resources, low cost, easy obtainment, good environmental compatibility and good adsorption capacity for pesticides with different structures and properties. The bentonite and the natural polymer gel are organically combined, so that the cost is effectively reduced, and the problem of too high gel slow release rate is solved;
(4) The gel prepared by the invention has the particle size of 5-25 mu m, the slow release effect of the pesticide can be improved on the premise of not influencing the mobility of the pesticide in the soil environment, and the particle size can be regulated and controlled by regulating the stirring rate and the ferric trichloride addition amount in the preparation process.
Drawings
FIG. 1 is a microscopic morphology of the gel particles prepared in example 3;
FIG. 2 is a gel microstructure of thiamethoxam loaded prepared in example 7;
FIG. 3 is a microstructure of the acetochlor-loaded gel prepared in example 8;
FIG. 4 is a gel microstructure of azoxystrobin-loaded gel prepared in example 9;
FIG. 5 thiamethoxam release rates in gel carriers at different temperatures;
FIG. 6 thiamethoxam release rates in gel carriers at different pH conditions;
FIG. 7 release rates of acetochlor in gel carriers at different temperatures;
FIG. 8 release rates of acetochlor in gel carriers at different pH conditions;
FIG. 9 release rates of azoxystrobin in gel carriers at different temperatures;
FIG. 10 release rates of azoxystrobin in gel carriers at different pH conditions;
FIG. 11 effect of gel on thiamethoxam photostability;
FIG. 12 effect of gel on the photostability of acetochlor;
FIG. 13 effect of gel on photo stability of azoxystrobin.
Detailed Description
The foregoing and/or other advantages of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings and detailed description. In the examples described below, the number average molecular weight of gamma-polyglutamic acid is 1000-3000kDa.
Example 1 preparation of gel particles.
And adding a certain amount of bentonite, gamma-polyglutamic acid and carboxymethyl cellulose into deionized water, and stirring at room temperature for 1000r/min until the bentonite, the gamma-polyglutamic acid and the carboxymethyl cellulose are completely and uniformly mixed to obtain a mixed solution. Wherein bentonite accounts for 2% of the total mass of the mixed solution, gamma-polyglutamic acid accounts for 1%, and carboxymethyl cellulose accounts for 5%. Adding a certain amount of ferric trichloride solution to make the mass percentage of ferric trichloride in the reaction system be 0.8%, stirring at room temperature for reaction for 0.5h, centrifuging and washing the product for 3 times (6000 rpm,10 min), and drying at 60 ℃ until the water content is less than 5%, thereby obtaining gel particles.
Example 2 preparation of gel particles.
Adding a certain amount of bentonite, gamma-polyglutamic acid and carboxymethyl cellulose into deionized water, and stirring at room temperature for 1000r/min until the bentonite, gamma-polyglutamic acid and carboxymethyl cellulose are completely and uniformly mixed. Wherein bentonite accounts for 2% of the total mass of the mixed solution, gamma-polyglutamic acid accounts for 2%, and carboxymethyl cellulose accounts for 4%. Adding a certain amount of ferric trichloride solution to make the mass percentage of ferric trichloride in the reaction system be 0.8%, stirring at room temperature for reaction for 1h, centrifuging and washing the product for 3 times (6000 rpm,10 min), and drying at 60 ℃ until the water content is less than or equal to 5%, thereby obtaining gel particles.
Example 3 preparation of gel particles.
Adding a certain amount of bentonite, gamma-polyglutamic acid and carboxymethyl cellulose into deionized water, and stirring at room temperature for 1000r/min until the bentonite, gamma-polyglutamic acid and carboxymethyl cellulose are completely and uniformly mixed. Wherein bentonite accounts for 2% of the total mass of the mixed solution, gamma-polyglutamic acid accounts for 3%, and carboxymethyl cellulose accounts for 3%. Adding a certain amount of ferric trichloride solution to make the mass percentage of ferric trichloride in the reaction system be 0.8%, stirring at room temperature for reaction for 0.5h, centrifuging and washing the product for 3 times (6000 rpm,10 min), and drying at 60 ℃ until the water content is less than or equal to 5%, thereby obtaining gel particles. FIG. 1 is an electron microscopic view of the prepared gel particles, and it can be seen from the figure that the size of the prepared gel particles is 5-25. Mu.m.
Example 4 preparation of gel particles.
Adding a certain amount of bentonite, gamma-polyglutamic acid and carboxymethyl cellulose into deionized water, and stirring at room temperature for 1000r/min until the bentonite, gamma-polyglutamic acid and carboxymethyl cellulose are completely and uniformly mixed. Wherein bentonite accounts for 2% of the total mass of the mixed solution, gamma-polyglutamic acid accounts for 4%, and carboxymethyl cellulose accounts for 2%. Adding a certain amount of ferric trichloride solution to make the mass percentage of ferric trichloride in the reaction system be 0.8%, stirring at room temperature for reaction for 0.5h, centrifuging and washing the product for 3 times (6000 rpm,10 min), and drying at 60 ℃ until the water content is less than 5%, thereby obtaining gel particles.
Example 5 preparation of gel particles.
Adding a certain amount of bentonite, gamma-polyglutamic acid and carboxymethyl cellulose into deionized water, and stirring at room temperature for 1000r/min until the bentonite, gamma-polyglutamic acid and carboxymethyl cellulose are completely and uniformly mixed. Wherein bentonite accounts for 2% of the total mass of the mixed solution, gamma-polyglutamic acid accounts for 5%, and carboxymethyl cellulose accounts for 1%. Adding a certain amount of ferric trichloride solution to make the mass percentage of ferric trichloride in the reaction system be 0.8%, stirring at room temperature for reaction for 0.5h, centrifuging and washing the product for 3 times (6000 rpm,10 min), and drying at 60 ℃ until the water content is less than 5%, thereby obtaining gel particles.
Example 6 gel swell test.
A mass of the dried gel particles prepared in examples 1 to 5 was immersed in the solutions of ph=4.0, ph=7.0 and ph=8.5, respectively, and samples were taken out of the solutions at intervals, and after the surface moisture was sucked up with filter paper, weighed and then put back into the solutions. All experiments were repeated three times. The Swelling Ratio (SR) was calculated according to the following formula:
Wherein W S and W d are the mass of swollen hydrogel and dry hydrogel, respectively.
As shown in Table 1, the gel prepared by the invention has smaller swelling rate under acidic conditions, and the swelling rate is increased along with the increase of pH, so that the gel prepared by the invention has the pH response release performance. In addition, an increase in the content of cohesive glutamic acid in the gel also leads to an increase in the swelling ratio of the gel.
TABLE 1 swelling ratio of gels at different pH conditions
Example 7 preparation of thiamethoxam loaded gel.
Adding a certain amount of thiamethoxam into the mixed solution of the water/organic solution dissolved with the Tween 80, and uniformly stirring to obtain the pesticide active ingredient solution. Wherein the thiamethoxam content is 5mg/mL. The dry gel particles prepared in examples 1-5 were mixed according to a mass ratio of 1:10 and reacted for 1h at room temperature, then washed with water and dried at room temperature. FIG. 2 is a microscopic morphology of thiamethoxam loaded gels prepared in example 7.
Example 8 preparation of a acetochlor loaded gel.
Adding a certain amount of acetochlor into the mixed solution of water/organic solution dissolved with Tween 80, and uniformly stirring to obtain the pesticide active ingredient solution. Wherein the thiamethoxam content is 5mg/mL. The dry gel particles prepared in examples 1-5 were mixed according to a mass ratio of 1:10 and reacted for 1h at room temperature, then washed with water and dried at room temperature. FIG. 3 shows the microstructure of the acetochlor-loaded gel prepared in example 8.
Example 9 preparation of azoxystrobin loaded gel.
Adding a certain amount of thiamethoxam into the mixed solution of the water/organic solution dissolved with the Tween 80, and uniformly stirring to obtain the pesticide active ingredient solution. Wherein the thiamethoxam content is 5mg/mL. The dry gel particles prepared in examples 1-5 were mixed according to a mass ratio of 1:10 and reacted for 1h at room temperature, then washed with water and dried at room temperature. Fig. 4 shows the gel microstructure of the azoxystrobin-loaded gel prepared in example 9.
Example 10 gel drug loading and encapsulation efficiency determination.
10Mg of drug-loaded gel is weighed, added into 5mL of dichloromethane for dissolution, and dried in vacuum after dissolution is complete. The dried product was dissolved in acetonitrile and fixed to a volume of 10mL, and after centrifugation through a membrane, the thiamethoxam content in the gel was measured by high performance liquid chromatography. Wherein, the mobile phase is acetonitrile, water=7:3, the flow rate is 0.5mL/min, the thiamethoxam detection wavelength is 254nm, and the acetochlor detection wavelength is 225nm; the azoxystrobin detection method is characterized in that a mobile phase is methanol/water=3:1, the flow rate is 0.8mL/min, and the detection wavelength is 254nm.
The drug loading and encapsulation efficiency were calculated according to the following formula:
drug loading = (thiamethoxam concentration in solution x solution volume)/drug loading gel mass x 100%
Encapsulation efficiency = actual drug amount/drug amount dosed x 100%
As shown in Table 2, table 3 and Table 4, the gel carrier prepared by the invention has higher drug loading and encapsulation efficiency, but the increase of the gamma-polyglutamic acid content can lead to the excessively high swelling rate of the gel carrier, so that the pesticide encapsulation efficiency is reduced, and therefore, the gel carrier prepared by the embodiment 3 has the best pesticide encapsulation effect.
Table 2: drug loading and encapsulation rate of thiamethoxam in gel
Table 3: drug-loading rate and encapsulation rate of acetochlor in gel
Table 4: drug loading and encapsulation efficiency of azoxystrobin in gel
Example 11 thiamethoxam loaded gel environmental response release test.
After taking a mass of the gel particles prepared in example 3 to prepare a drug-loaded gel according to the procedure described in example 7, 20mg of the gel was weighed and dispersed in a dialysis bag containing 2.0mL of release medium, and then the dialysis bag was placed in a dissolution tester and added to 200mL of release medium. The rotation speed was set at 100r/min and the temperature was set at 30 ℃. The release medium consisted of phosphate buffer, ethanol and Tween-80 emulsifier (140:59:1, V/V/V). The cumulative release of thiamethoxam was calculated by measuring the concentration of thiamethoxam in the release medium at different times. At regular time intervals, 1mL of the release solution was removed for HPLC analysis while 1mL of fresh release solution was added to maintain a constant volume. The release behavior of the drug-loaded gel under different conditions was investigated by setting different pH values (4.0, 7.0 and 8.5) and temperatures (10, 25 and 35 ℃), respectively.
As shown in fig. 5, the increase in temperature also accelerates the slow release rate of thiamethoxam in the gel. After 50h, thiamethoxam is released 80% at 35 ℃ and only 30% at 10 ℃ because the non-covalent interactions between the gel and the drug are mainly van der waals and hydrogen bonds, which decrease with increasing temperature, thus facilitating pesticide release. As shown in fig. 6, the slow release rate of thiamethoxam in the gel under alkaline conditions is significantly accelerated. The thiamethoxam release rate reached 90% after 50h at ph=8.5, whereas the in-gel thiamethoxam release rate was 65% at ph=4. This is because carboxymethyl cellulose and polyglutamic acid both have a large number of carboxyl groups, and electrostatic repulsive force is formed between the two polymers under alkaline conditions, which results in an increase in the swelling rate of the gel and an increase in the release rate.
Example 12 load acetochlor gel environmental response release test.
After taking a mass of the gel particles prepared in example 3 to prepare a drug-loaded gel according to the procedure described in example 7, 20mg of the gel was weighed and dispersed in a dialysis bag containing 2.0mL of release medium, and then the dialysis bag was placed in a dissolution tester and added to 200mL of release medium. The rotation speed was set at 100r/min and the temperature was set at 30 ℃. The release medium consisted of phosphate buffer, ethanol and Tween-80 emulsifier (140:59:1, V/V/V). The cumulative amount of acetochlor released was calculated by measuring the concentration of acetochlor in the different time release media. At regular time intervals, 1mL of the release solution was removed for HPLC analysis while 1mL of fresh release solution was added to maintain a constant volume. The release behavior of the drug-loaded gel under different conditions was investigated by setting different pH values (4.0, 7.0 and 8.5) and temperatures (10, 25 and 35 ℃), respectively.
As shown in fig. 7, the increase in temperature also accelerates the slow release rate of acetochlor in the gel. After 50h, the acetochlor released 77% at 35℃and only 32% at 10 ℃. As shown in fig. 8, the slow release rate of acetochlor in the gel under alkaline conditions was significantly accelerated. The release rate of acetochlor reaches 91% after 50 hours at ph=8.5, whereas the release rate of acetochlor in the gel at ph=4 is 60%.
Example 13 azoxystrobin loaded gel environmental response release test.
After taking a mass of the gel particles prepared in example 3 to prepare a drug-loaded gel according to the procedure described in example 7, 20mg of the gel was weighed and dispersed in a dialysis bag containing 2.0mL of release medium, and then the dialysis bag was placed in a dissolution tester and added to 200mL of release medium. The rotation speed was set at 100r/min and the temperature was set at 30 ℃. The release medium consisted of phosphate buffer, ethanol and Tween-80 emulsifier (140:59:1, V/V/V). The cumulative amount of acetochlor released was calculated by measuring the concentration of azoxystrobin in the release medium at different times. At regular time intervals, 1mL of the release solution was removed for HPLC analysis while 1mL of fresh release solution was added to maintain a constant volume. The release behavior of the drug-loaded gel under different conditions was investigated by setting different pH values (4.0, 7.0 and 8.5) and temperatures (10, 25 and 35 ℃), respectively.
As shown in fig. 9, the increase in temperature also accelerates the slow release rate of azoxystrobin in the gel. After 50h, the azoxystrobin was released 85% at 35℃and only 35% at 10 ℃. The data show that the pesticide loaded gel prepared by the invention has the function of environment response controlled release. As shown in fig. 10, the slow release rate of azoxystrobin in the gel under alkaline conditions was significantly accelerated. At ph=8.5, the release rate of azoxystrobin reached 87% after 50h, whereas the release rate of azoxystrobin in the gel at ph=4 was 63%.
Example 14 thiamethoxam photostability test.
The gel containing 0.4mg thiamethoxam was dispersed in a quartz tube containing 20ml of a 20% aqueous acetonitrile and irradiated under a 500W high pressure mercury lamp. Meanwhile, the commercial thiamethoxam water dispersible granule is used as a Control (CK), the reaction temperature is controlled to be 20 ℃, 0.8mL of thiamethoxam water dispersible granule is sampled at different time intervals, and HPLC analysis is carried out through a filter membrane with the pore diameter of 0.45 mu m.
As shown in FIG. 11, the gel prepared by the present invention effectively improves the photostability of thiamethoxam. After strong light irradiation for 6 hours, the medicine content of the commercial thiamethoxam water dispersible granule is only 27%, and the residual content of thiamethoxam in gel is above 65%.
Example 15 acetochlor photostability test.
The gel containing 0.4mg acetochlor was dispersed in a quartz tube containing 20mL of 20% acetonitrile in water and irradiated under a 500W high-pressure mercury lamp. Meanwhile, the commercial acetochlor water dispersible granule is used as a Control (CK), the reaction temperature is controlled to be 20 ℃, 0.8mL is sampled at different time intervals, and HPLC analysis is carried out through a filter membrane with the pore diameter of 0.45 mu m.
As shown in FIG. 12, the gel prepared by the present invention effectively improves the photostability of acetochlor. After the strong light irradiates for 6 hours, the medicine content of the water dispersible granule of the commercial acetochlor only remains 40 percent, and the residual content of the acetochlor in the gel is more than 70 percent.
Example 16 photo stability test of azoxystrobin.
The gel containing 0.4mg of azoxystrobin was dispersed in a quartz tube containing 20mL of 20% acetonitrile in water and irradiated under a 500W high pressure mercury lamp. Meanwhile, the commercially available azoxystrobin water dispersible granule is used as a Control (CK), the reaction temperature is controlled to be 20 ℃, 0.8mL is sampled at different time intervals, and HPLC analysis is carried out through a filter membrane with the aperture of 0.45 mu m.
As shown in FIG. 13, the gel prepared by the invention effectively improves the photostability of azoxystrobin. After strong light irradiation for 6 hours, the drug content in the commercially available azoxystrobin water dispersible granule is only 55%, and the residual azoxystrobin content in the gel is above 65%.
The invention provides a pesticide loaded hydrogel with environment response controlled release, and a method for preparing the same, and a method for realizing the technical scheme. The components not explicitly described in this embodiment can be implemented by using the prior art.
Claims (7)
1. A method for preparing a pesticide loaded gel with environmentally responsive controlled release, comprising the steps of:
(1) Preparation of gel particles: adding bentonite, gamma-polyglutamic acid and carboxymethyl cellulose into deionized water, stirring to obtain a mixed solution which is completely and uniformly mixed, adding ferric trichloride solution, continuously stirring for reaction, sequentially centrifuging and washing the product, and drying until the water content is less than or equal to 5% to obtain gel particles;
(2) Preparation of pesticide active ingredient solution: adding the pesticide active ingredient into the mixed solution of the water/organic solution dissolved with the Tween 80, and uniformly stirring to obtain a pesticide active ingredient solution;
(3) And (3) preparing the gel loaded with the pesticide active ingredients: adding the gel particles obtained in the step (1) into the pesticide active ingredient solution prepared in the step (2), reacting, and separating and drying to obtain pesticide loaded gel particles; in the step (1), bentonite accounts for 1-2% of the total mass of the mixed solution, gamma-polyglutamic acid accounts for 1-5% of the total mass of the mixed solution, and carboxymethyl cellulose accounts for 1-5% of the total mass of the mixed solution; the adding amount of the ferric trichloride is 0.1-0.8% of the ferric trichloride in the reaction system; the mass ratio of the pesticide active ingredient solution to the gel particles is 10:1-50:1.
2. The method according to claim 1, wherein the gamma-polyglutamic acid is pure gamma-polyglutamic acid or gamma-polyglutamate; wherein the number average molecular weight of the gamma-polyglutamic acid is 1000-3000 kDa.
3. The preparation method according to claim 1, wherein in the step (1), after bentonite, gamma-polyglutamic acid and carboxymethyl cellulose are added into deionized water, the mixture is stirred at room temperature of 1000 r/min to obtain a mixed solution, and the ferric trichloride solution is added, and the stirring reaction at room temperature is continued for 0.5-1 h.
4. The preparation method according to claim 1, wherein in the step (1), the gel particles are obtained after the product is centrifugally washed 3-4 times and dried at 60-80 ℃ until the water content is less than or equal to 5%, and the centrifugation conditions are 5000-6000 rpm and 10-20 min each time.
5. The method according to claim 1, wherein in the step (2), the pesticidal active ingredient is any one of thiamethoxam, acetochlor, or azoxystrobin.
6. The method of claim 1, wherein the content of the agrochemical active ingredient in the agrochemical active ingredient solution is 2 to 5 mg/mL.
7. The preparation method of claim 1, wherein the organic solvent in the step (2) is ethanol, the volume ratio of water to the organic solvent is 1:1-1:5, and the content of tween 80 is 0.4-0.6% of the mass of the mixed solution of water and the organic solution.
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