Preparation And Properties Of Multifunctional Graphene Oxide-based Intelligent Controlled-release Nano-pesticide Formulations

China is a agricultural country,and agriculture is the lifeblood of the national economy.As an irreplaceable means of production,pesticides play an indispensable role in the agricultural field.At present,the yield of pesticide technicals in our country is growing rapidly,but the innovation of pesticide formulations is lagging behind,and there are problems such as simple formulation structure,few new formulations,unstable quality and serious environmental pollution.As a result,the pesticide industry is still at the low end of the global pesticide supply chain.Traditional pesticide formulations not only have low use efficiency and poor stability,but also pose a great threat to the environment.Therefore,it has become an important task for the pesticide industry to develop pesticide formulations with good water solubility,high stability,long duration,and environment-friendly to replace traditional pesticide formulations with high toxicity,high residue,and low stability.The expansion of nanotechnology into the field of pesticides and the formation of a nano-pesticide system can effectively solve the above problems.The advantages of nano-pesticides include reduced drug toxicity,leaching loss,volatilization,drift,and high safety and environmental friendliness during application.In addition,a large amount of pesticides will be consumed during the spraying process,resulting in low utilization of target crops and insufficient pesticide doses for harmful organisms.Therefore,while developing nano-pesticide formulations,we should also devote more energy to the precise release direction of nano-pesticides.Graphene oxide(GO)is the oxide of graphene,a new type of two-dimensional carbon material with monolithic layer.Compared with graphene,graphene oxide have many oxygen-containing functional groups,which are easier for surface modification.The double-sided polycyclic aromatic structure gives it a large specific surface area and a large delocalized π-electron system.This increases the types of interactions that may occur on the surface of graphene oxide.And because of graphene oxide has good stability and water solubility,it is expected to become a new material for nanopesticide formulation carriers.Hence,this thesis designed a series of multifunctional graphene oxide-based nanofunctional carriers to load poorly soluble pesticide technicals,constructed an intelligent controlled-release nanopesticide formulation system,and systematically studied its water solubility,stability,adhesion performance,safety,and controlled-release performance to try to solve the problems of traditional pesticide formulations.The main research contents are as follows:(1)Preparation and properties of intelligent temperature controlled-release lambda-cyhalothrin nanoformulations.Firstly,graphene oxide was prepared by the traditional Hummers method,and then the temperature-sensitive material Poly(N-isopropyl acrylamide)(PNIPAm)was used for surface modification to form the PNIPAm-GO functional carrier,and finally via simple physical adsorption to load Lambda-cyhalothrin(LC),to prepare the lambda-cyhalothrin nanoformulation(LC@PNIPAm-GO).The successful preparation of the material was proved by SEM,XRD,FTIR,XPS;and its good thermal stability was measured by TGA,DSC.Use ultraviolet spectrophotometer method to determine its drug loading is about 30%.The safety performance via the MTT cytotoxicity test was evaluated,the results showed that the LC@PNIPAm-GO has good safety performance and environmental friendly.The excellent sustained release performance and temperature controlled-release performance of LC@PNIPAm-GO was proved by the invitro simulated release experiment.(2)Preparation and properties of intelligent pH controlled-release emamectin benzoate nanoformulations.In addition to temperature controlled release,the controlled release of pesticides can also be achieved through external pH changes.In the second system,we prepared a smart pH controlled release emamectin benzoate nanoformulation and explored its performance.Firstly,graphene oxide was prepared by the traditional Hummers method,and then the pH-sensitive material Chitosan(CS)was used for surface modification to form the CS-GO functional carrier,and finally via simple physical adsorption to load emamectin benzoate(EB),to prepare the emamectin benzoate nanoformulation(EB@CS-GO).The successful preparation of the material was proved by SEM,XRD,FTIR,XPS;and its good thermal stability was measured by TGA,DSC.Use ultraviolet spectrophotometer method to determine its drug loading is about 40%.Its good wetting performance and deposition performance are proved by contact angle test and retention rate on the foliage surfaces.The safety performance via the MTT cytotoxicity test was evaluated,the results showed that the EB@CS-GO has good safety performance and environmental friendly.The excellent sustained release performance and pH controlled-release performance of EB@CS-GO was proved by the invitro simulated release experiment.(3)Preparation and properties of intelligent photothermal and pH dual controlled-release acetamiprid nanoformulations.In the third system,we learned from the experience of the first two systems,prepared a pH and photothermal dual controlled release acetamiprid nano-formulation,and explored its performance.Firstly,graphene oxide was prepared by the traditional Hummers method,and then the photothermal and pH sensitive material Polydopamine(PDA)was used for surface modification to form the PDA-GO functional carrier,and finally via simple physical adsorption to load acetamiprid(AC),to prepare the acetamiprid nanoformulation(AC@PDA-GO).The successful preparation of the material was proved by SEM,XRD,FTIR,XPS;and its good thermal stability was measured by TGA,DSC.Use ultraviolet spectrophotometer method to determine its drug loading is about 30%.Its good wetting performance and deposition performance are proved by contact angle test and retention rate on the foliage surfaces.The safety performance via the MTT cytotoxicity test was evaluated,the results showed that the AC@PDA-GO has good safety performance and environmental friendly.AC@PDA-GO excellent sustained release performance and the dual controlled-release performance of photothermal and pH was proved by the invitro simulated release exper.Finally,AC@PDA-GO high-efficiency pest control ability has been proved through biological experiments of Plutella xylostella,which has great potential in the field of practical pesticide application.