As a "crop security guard", pesticides play an irreplaceable role in preventing major biological disasters and maintaining food security and stable production. According to the statistics of relevant departments, China's annual crop chemical control area has reached 8 billion per mu, can save the food loss of more than 100 billion jin, however, China's unit area of pesticide use is 2.5 times higher than the world average level, the effective utilization rate is lower than the developed countries in Europe and the United States 11-20 percentage points, the pesticide industry is facing new challenges to green and efficient accelerated transformation and development.
"Nano pesticide" refers to a new pesticide dosage form with nanometer scale (< 100nm) or nanometer carrier structure created by nanotechnology, which can significantly improve the effectiveness, safety, target specificity and biological resistance of pesticides, and is the mainstream of future green pesticide innovation and development. It has been selected by the International Union of Pure and Applied Chemistry as one of the major emerging chemistry technologies that will change the world.
Since the "11th Five-Year Plan", with the support of national science and technology projects such as "863 Plan", "973 Plan", key research and development Plan, and Natural Science Foundation, the Research Center of NanoAgriculture (Institute of Environmental Protection) of the Chinese Academy of Agricultural Sciences and the Institute of Plant Protection, the Institute of Chemistry of the Chinese Academy of Agricultural Sciences, the National Nanoscience Center, as well as Tsinghua University and Tianjin University and other relevant superior scientific research institutions, Through long-term interdisciplinary collaborative innovation, systematic and pioneering research progress has been made in the theory and application of nano pesticides, breaking through key theoretical and technical constraints such as the assembly and synthesis of nano pesticides, dosage form design, preparation process and process integration, and forming a core preparation technology system of nano pesticides with independent intellectual property rights. It has laid a scientific and technological foundation for promoting the transformation and upgrading of China's pesticide industry and the green development of agriculture. At present, China's nano pesticide industrialization has been gaining momentum, and the nano pesticide industry standards are also about to be introduced with the support of the Ministry of Agriculture and other relevant competent departments.
China's nano pesticide research has made the following significant progress:
First, the creation principle and method of green nano pesticide were established. By using molecular assembly, template synthesis, crystal nucleus precipitation, coordination complexation, chemical modification and other nanomaterial preparation technologies, a number of efficient and safe new nanomaterial drug delivery systems and their configuration design, assembly synthesis and function regulation methods were constructed, and a new mode of green nanomaterial pesticide creation with the functions of targeted transport and intelligent release was established. By using the size effect, interface effect, tunnel effect, intelligent transmission and environmental response characteristics of nano pesticides, the physicochemical properties, dose-effect relationship, target mode of action and dose transmission characteristics of drugs are improved, and the accurate release of drugs in space, time and dose is realized, which can significantly improve the effective utilization rate of pesticides, extend the effective period, enhance the efficacy function and control effect.
The second is to create a batch of high efficiency, safety and low residue nano pesticide preparations. Aiming at large tonnage and dominant insecticides, fungicides and herbicides, new dosage forms of green nano pesticides such as nano-micro-emulsion, suspension, capsule, hydrosol and solid dispersion were developed, and their synergies and emission reduction effects, application range, optimal dosage and application methods were determined. It can increase the drug effect by 30-50% on average, extend the duration of effect by 4-5 times, and significantly reduce residual pollution.
Third, the safety improvement mechanism of nanometer pesticide was revealed. Toxicological tests showed that nano pesticides can reduce agricultural residues, environmental pollution and non-target biological toxicity by improving quality and efficiency, and have no adverse effects on crop growth and development, and will not cause secondary health and environmental risks.
The fourth is to establish the key preparation technology and process equipment of nanometer pesticide. The core common preparation technology system of nanometer pesticides such as melting method, crystal nucleus precipitation method, micro-precipitation method and emulsion polymerization method was invented, and the mass production production process and equipment system was established, which laid the foundation for promoting the industrialization of nanometer pesticides on a large scale.
Compared with traditional pesticides, the main advantages of nano pesticides are: first, improve the water solubility of insoluble drugs and improve the bioavailability. It has broken through the technical bottleneck that 70% of traditional pesticides are difficult to dissolve in water and water-based dispersion, improved the water solubility, dispersion and conductivity of drugs, and promoted the targeted transmission and absorption and utilization. The second is to improve the adhesion and retention ability of leaf surface and inhibit the off-target and loss of chemicals. Overcome the barrier of liquid deposition on the hydrophobic leaf surface of rice, wheat and corn, reduce the loss of drug effect such as liquid shedding, dust drift and rain erosion, and greatly improve the effective utilization rate. The third is to enhance the performance of accurate drug release to the target, reduce the dose and the number of operations. According to the dose requirements of pest prevention and control, the drug is continuously released at the lowest effective concentration to improve the stability and duration of the drug effect, and reduce the amount of pesticide use and application times. The fourth is to achieve increased efficiency and emission reduction of pesticides to improve the safety of use. By improving quality and efficiency, the effective control dose can be reduced, harmful residue emissions can be reduced, and non-target biological toxicity can be reduced, thereby improving food, environmental and biological safety.
