Construction Of Supramolecular Hybrid Hydrogels Based On Polysaccharide For Controlled-release Of Pesticides Application

Pesticides are considered the effective way to protect crops and maintain economic efficiency in modern agriculture.However,most traditional pesticides have the disadvantages of poor dispersity,easy decomposition and low utilization.In addition,the excessive use and abuse of pesticides also cause serious environmental pollution and food safety risks.In order to solve this problem,environmentally responsive pesticide controlled release vector has received a lot of attention and research.In view of this,it is of great significance to develop a convenient and degradable controlled release system for pesticides to improve the efficiency of pesticide use and control the continuous release of pesticides.Therefore,this thesis mainly uses natural polysaccharides and natural clay as raw materials and constructs green and environment-friendly pesticide delivery systems by means of supramolecular self-assembly,which provides a new idea and strategy for enhancing the efficiency of agrochemical utilization.The main contents are as follows:(1)An environmentally friendly,light-sensitive hyaluronic acid supramolecular hybrid hydrogel(HA-AAP-Guano-CD@LP)was constructed by supramolecular self-assembly method using arylazoprazole modified hyaluronic acid(HA-AAP),guanidine functionalized β-cyclodextrin(Guano-CD)and lithium saponite clay(LP)as raw materials.They were characterized by SEM,Zeta potential and rheological tests.Plant growth regulators naphthylacetic acid and gibberellin were loaded into the threedimensional network structure of the hydrogel,and the gel-sol transition was regulated by light stimulation to achieve controlled drug release.Plant growth regulation experiments showed that the HA-AAP-Guano-CD@LP drug loading system could effectively promote the growth of Chinese cabbage and alfalfa and increase the accumulation of organic matter.Subsequently,the hydrogel after the release of pesticides could also capture heavy metal ions through the strong complexation between ions and carboxyl groups,and fix soil pollutants in situ.This work may provide a new strategy for the controlled-release of pesticide and synergistic adsorption of pollutants.(2)Using cetyltrimethyl ammonium bromide(CTAB),N-trimethyl chitosan(TMC),hydroxypropyl trimethyl ammonium chloride chitosan(HACC)and LP as raw materials,the supramolecular hybrid hydrogels CTAB@LP-TMC and CTAB@LP-HACC using chitosan as shell were constructed by the electrostatic interaction between CTAB and quaternary ammonium chitosan and LP.It was characterized by SEM,Zeta potential and rheology test.Naphthoacetic acid and gibberellin were loaded by the three-dimensional network structure of hydrogel,and the sustained release of pesticides could be realized.The experiment of plant growth regulation showed that CTAB@LP-TMC and CTAB@LP-HACC loaded with plant growth regulator could promote the growth of Chinese cabbage and alfalfa.Subsequently,the antibacterial activities of CTAB@LP-TMC and CTAB@LP-HACC against Bostonia cinerea,sweet potato interstitium and maize macrospot were evaluated by mycelium growth rate method.This study may provide a promising method for achieving sustained release of pesticides and inhibiting the growth of plant pathogens.