CN-122011379-A - Star-shaped cationic nano-carrier, preparation method thereof, nano-pesticide prepared by using star-shaped cationic nano-carrier and application of nano-pesticide in pear antifreezing

Abstract

The invention belongs to the technical field of pear young fruit freezing prevention, and particularly relates to a star-shaped cationic nano-carrier, a preparation method thereof, a prepared nano pesticide and application thereof in pear young fruit freezing prevention. The star-shaped cationic nano-carrier is obtained by amidation reaction of branched polyethylenimine and tung oil at high temperature, and the nano-carrier and methyl jasmonate can spontaneously form a stable nano-structure, namely star-shaped cationic methyl jasmonate nano-pesticide in a water phase.

Inventors

• JIA BING
• PAN LINNA
• LIU CHAOGANG
• YANG GUANG
• LIU LUN

Assignees

• 安徽农业大学
• 安徽省砀山县园艺场
• 砀山县三联果蔬专业合作社

Dates

Publication Date

20260512

Application Date

20260120

Claims (10)

1. 1. The star-shaped cationic nano-carrier is characterized in that the structural general formula of the nano-carrier is shown as the formula (I): (I)。
2. 2. A method for preparing a star-shaped cationic nano-carrier according to claim 1, comprising the steps of: S1, adding polyethylenimine and tung oil into N, N-dimethylformamide according to a molar ratio of 12:1, stirring and dissolving until the mixture is uniform, and obtaining a mixed solution; S2, carrying out reflux reaction on the mixed solution at 80-100 ℃ for 12h, dialyzing the reacted mixed solution, and intercepting a product with molecular weight of more than 7000-7500 Da to obtain the star-shaped cationic nano-carrier.
3. 3. The method of claim 2, wherein the polyethyleneimine has a weight average molecular weight of 35 to 60 and the N, N-dimethylformamide has a purity of greater than 99.9%.
4. 4. The method of claim 3, wherein the polyethyleneimine has a weight average molecular weight of 43.07.
5. 5. Use of the star cationic nanocarriers of claim 1 to increase the adhesion of nano pesticides.
6. 6. A star cationic methyl jasmonate nano pesticide, comprising the star cationic nano carrier according to claim 1 and an effective dose of methyl jasmonate loaded on the star cationic nano carrier.
7. 7. The star-shaped cationic methyl jasmonate nano pesticide according to claim 6, wherein the nano pesticide is prepared by adding the star-shaped cationic nano carrier, methyl jasmonate and deionized water into deionized water according to a set mass ratio, and stirring, wherein the star-shaped cationic nano carrier and the methyl jasmonate are self-assembled to obtain the required nano pesticide.
8. 8. The star-shaped cationic methyl jasmonate nano pesticide according to claim 6 or 7, wherein the concentration of the star-shaped cationic nano carrier in the nano pesticide is 0.1-2.0 mg/mL, and the mass ratio of the star-shaped cationic nano carrier to the methyl jasmonate is 1 (0.1-0.5).
9. 9. Use of the star cationic methyl jasmonate nano pesticide according to any one of claims 6-8 for improving the frost resistance of young pear fruits.
10. 10. The use according to claim 9, wherein the nano pesticide is sprayed three times continuously at a set interval of 12 h and a single spraying amount of 0.5-1.5L/plant on the 7 th to 15 th days after flower filling of pear tree.

Description

Star-shaped cationic nano-carrier, preparation method thereof, nano-pesticide prepared by using star-shaped cationic nano-carrier and application of nano-pesticide in pear antifreezing Technical Field The invention belongs to the technical field of pear young fruit freezing prevention, and particularly relates to a star-shaped cationic nano-carrier, a preparation method thereof, a prepared nano pesticide and application thereof in pear young fruit freezing prevention. Technical Field Pear trees are important economic fruit trees, but in early spring festival, young pear fruits and flowering period are extremely vulnerable to night frost damage. When encountering low-temperature stress, the young fruit cell membrane system is damaged, physiological metabolism is disturbed, so that the development of fruits is stagnated, rust spots are generated on the surfaces of the fruits, and even a large number of fruits fall, destructive striking is caused on the yield and quality of pears, and huge economic loss is brought to fruit farmers. The traditional anti-freezing measures for the orchard mainly comprise a fumigation method, a water filling method, an anti-freezing agent spraying method and the like. However, the methods have obvious limitations that the smoke method pollutes the environment and is severely restricted by the weather conditions, the water resource requirement of the irrigation method is high, and the occurrence of diseases and insect pests of an orchard is possibly aggravated, and the conventional chemical antifreezing agent is often unstable in effect, short in duration and capable of causing the problems of phytotoxicity or environmental residues when used in a large amount. Therefore, development of efficient, safe and convenient anti-freezing technology for young pears has become an urgent need for healthy development of pear industry. In recent years, the plant endogenous hormone methyl jasmonate (MeJA) as a highly efficient "signal molecule" has shown great potential in inducing plants to develop systemic stress resistance. Research shows that exogenous spraying of MeJA can effectively activate the defense system of plants, induce the expression of cold-resistant related genes (such as COR, LEA and the like), promote the accumulation of soluble sugar, proline and other permeation regulating substances, stabilize the cell membrane structure, and thus obviously improve the tolerance of the plants to low-temperature freeze injury. The novel thinking is provided for developing novel biological source antifreezing agents. However, the direct application of methyl jasmonate to field production still faces a number of technical bottlenecks: (1) The stability is poor, methyl jasmonate is easy to volatilize and photolyze, and effective components remained on leaf surfaces and fruit surfaces after field spraying can be rapidly degraded, so that the actual action time window is short, and the effective components are difficult to continuously play roles before critical frost comes. (2) The absorption efficiency is low, and the hydrophobic cuticle on the surface of the plant leaf and the wax layer on the fruit epidermis form a natural physical barrier, so that lipophilic MeJA molecules are difficult to be efficiently and rapidly absorbed and transported by plant tissues. (3) The targeting is lacking, the conventional preparation cannot preferentially convey the active ingredients to key parts such as young fruits which are most susceptible to freeze injury, so that the waste of the active ingredients is caused, and the utilization rate is low. The drug delivery system capable of improving stability of methyl jasmonate, promoting absorption of methyl jasmonate and acting on young fruits accurately is provided, and has extremely important theoretical and practical significance for breaking through the bottleneck of methyl jasmonate in agricultural stress-resistant application and realizing upgrading and updating of the young pear antifreezing technology, and is a technical problem to be solved urgently at present. Disclosure of Invention In order to solve the problems in the prior art, one of the purposes of the invention is to provide a star-shaped cationic nano-carrier, wherein the structural general formula of the nano-carrier is shown as formula I: I。 The second object of the present invention is to provide a preparation method of the star-shaped cationic nano-carrier, which comprises the following steps: s1, adding polyethylenimine and tung oil into N, N-dimethylformamide according to a molar ratio of 12:1, stirring and dissolving until the mixture is uniform, and obtaining a mixed solution; S2, carrying out reflux reaction on the mixed solution at 80-100 ℃ for 12h, dialyzing the reacted mixed solution, and intercepting a product with molecular weight of more than 7000-7500 Da to obtain the star-shaped cationic nano-carrier. Preferably, the weight average molecular weight of the polyethyleneimine is