The invention belongs to the field of nanotechnology and relates, in particular, to a water-based nano-pesticide made of graphene oxide for the prevention and control of fungal diseases in crops, and to a process for its preparation and use.
Water-Based Graphene Oxide Nanopesticide
The bactericide in the water-based graphene oxide nanopesticide adheres to the surface of the graphene oxide by the pi-pi conjugation effect, hydrogen bonding effect and electrostatic adsorption effect, the fungal cells are damaged by the graphene oxide, and then the drug is released accurately, so that efficient use of the drug is realized, and the graphene oxide and the pesticide show excellent synergistic mechanism.
When the water-based graphene oxide nanopesticide prepared by the emulsification freeze-drying method is used to prevent and control plant fungal diseases, the drift problem of the nanopesticide is alleviated. And the water-soluble nano pesticide has good water solubility and anti-drift performance, and is a novel water-based nano pesticide.
Water-based graphene oxide nano-pesticide and method for its production and application.
The invention belongs to the field of nanotechnology, and more particularly relates to a water-based graphene oxide nanopesticide for the prevention and control of fungal diseases in crops, and to a production process and application thereof.
The conventional pesticide has the problems of poor dispersibility, poor stability, low biological activity, low degradation rate and the like due to the fact that the drug-laden particles of the conventional pesticide are large, the use rate of the target plants is less than 30%, and the dosage of the harmful organisms is less than 0.1%.
The data show that the pesticide can be sprayed on the field, and the loss of the pesticide by dripping, dust drift, rain washing and the like can be more than 70%.
The use of a large amount of pesticide leads to significant environmental pollution and excessive pesticide residue, and seriously threatens people’s physical and mental health.
Nanotechnology can effectively reduce pesticide residue pollution and improve the effective use rate of pesticides. In addition, the nano-drug delivery system has the advantages of improving the dispersibility, stability and use rate of the pesticide, extending the shelf life, reducing the residual amount and the like.
Graphene is a two-dimensional nanomaterial consisting of a single layer of carbon atoms, first discovered in 2004 by British scientists Novoselov and Gemm et al. Graphene oxide is a derivative of graphene and has a surface rich in oxygen-containing functional groups, so the graphene oxide has good water solubility and stability.
At the same time, the graphene oxide also has the ability to load the medicine with a structure similar to a benzene ring by pi-pi accumulation, hydrophobic effect and hydrogen bonding effect, so the graphene oxide is widely used in the field of biological medicine.
The blade of the two-dimensional graphene oxide nanomaterial is called a nanometer and can cut cell membranes of bacterial cells. The normal metabolism of bacterial cells can be affected by oxidative stress mechanism, leading to cell death.
When a large amount of graphene oxide nanosheets is adsorbed on the surface of bacterial cells, the bacteria can be completely enveloped, so that they are physically isolated from the environment and the microorganisms slowly die. The sterilization mechanism shows that the two-dimensional graphene oxide can be used as a drug carrier to achieve antibacterial synergistic effect.
Invention patent application number 201310550703.7 discloses a manufacturing process for thiophanate methyl nanopesticides that reduces dosage and improves the effect of the pesticide. However, the existing patents on nano-pesticides mainly deal with the synergy of nano-pesticides, and the problem of nano-pesticide drift cannot be solved.
Disclosure of the Invention
In order to overcome the shortcomings of conventional pesticides and solve the environmental and social problems caused by conventional pesticides, the invention mainly aims to provide a method for producing a water-based graphene oxide nano-pesticide for preventing and controlling fungal diseases of crops.
The invention also aims to provide the water-based graphene oxide nanopesticide produced by the manufacturing process. The nano-pesticide has good water solubility and anti-drift performance, can obviously improve the sterilization ability of the pesticide, and realizes the reduction and synergism of the pesticide.
The invention further aims to enable the application of the water-based graphene oxide nano-pesticide.
To achieve the purpose, the technical scheme adopted by the invention is as follows:
A production process for a water-based graphene oxide nanopesticide comprises the following steps:
(1) dissolving graphene oxide in water and vigorously stirring to form an aqueous graphene oxide dispersion; dissolving the bactericide in dimethyl sulfoxide, N-N-dimethylformamide or methanol to form an organic phase bactericide solution;
the concentration of the aqueous dispersion of graphene oxide is 0.5-1 g/L;
the concentration of the bactericide solution is 1.25: 1-3.75: 1;
(2) dropwise addition of the bactericide solution into the aqueous graphene oxide dispersion with vigorous stirring and vigorous stirring for 24-48 hours after dropwise addition to obtain a mixed solution, removal of the free pesticide molecules by dialysis or purification of the reaction liquid, removal of the supernatant by high-speed centrifugation and freeze-drying to obtain a product, namely the solid water-based graphene oxide nanopesticide;
the mass ratio of the bactericide to the graphene oxide in the mixed solution is 2: 1-2: 3;
(3) dispersing the solid water-based graphene oxide nanopesticide in an aqueous solution in the ratio of 1: 100-1000, adding 1% Tween 80 and oscillating to obtain an emulsion, namely the water-based graphene oxide nanopesticide.
Preferably, the bactericide is carbendazim or epoxiconazole, which is suitable for the prevention and treatment of fungal diseases.
Preferably, the dialysis time is 6 hours.
Preferably, the number of washes with the reaction solution is 3.
Preferably, the rotation speed of the high-speed centrifugation is 10000 rpm.
The invention further provides the water-based graphene oxide nanopesticide prepared by the preparation method.
The invention further provides the application of the water-based graphene oxide nanopesticide in the prevention and control of fungal diseases of crop plants, wherein the fungal diseases of crop plants include rice blast, banded sclerotial blight, powdery mildew, damping off, anthracnose or leaf spot.
Compared with the prior art, the invention has the following advantages and beneficial effects:
The bactericide in the water-based graphene oxide nanopesticide (GO carbendazim) prepared by the invention adheres to the surface of the graphene oxide through the pi-pi conjugation effect, hydrogen bonding effect and electrostatic adsorption effect, and the graphene oxide damages the fungal cells so that the drug is released accurately, the efficient use of the drug is realized, and the graphene oxide and the pesticide have an excellent synergistic mechanism.
When the water-based graphene oxide nanopesticide prepared by the emulsification freeze-drying process is used to prevent and control fungal diseases in plants, the hydrophobic surface of the two-dimensional sheet structure of the graphene oxide can easily attach to the plant leaves, so that the entrained nanopesticide can easily attach to the surface of the plants and solve the problem of the drift of the nanopesticide.
The present invention is described in more detail with reference to examples, but embodiments of the present invention are not limited thereto. For process parameters not specifically mentioned, reference may be made to conventional techniques.