pH/redox dual responsive from natural polymer-based nanoparticles for on-demand delivery of pesticides

With the increase in global food demand and the destruction of environment, the development of sustainable agriculture has become increasingly more important. Stimuli-responsive controlled-release agrochemicals enhance the bioavailability of active ingredients and reduce the frequency of use and environmental pollution. Herein, 3,3′-dithiodipropionic acid was used as a functional bridge to covalently link the degradable natural polymer zein and chitosan oligosaccharides (CS) to prepare a water-dispersed environmentally friendly pesticide carrier. Subsequently, via hydrophobic and hydrogen bonding interactions photo-decomposable avermectin (AVM) was encapsulated forming a stimuli-responsive intelligent nanopesticide delivery system (AVM@CS-SS-Zein) was developed by encapsulating in the carrier. AVM was released slowly from AVM@CS-SS-Zein particles in a neutral condition and was released rapidly under stimulation of glutathione and alkalinity in simulated insects. The photostability of AVM@CS-SS-Zein was improved by 6-fold compared with that of AVM and the nanoparticles had good adherence to the leaves, slowly releasing AVM and avoiding the light decomposition of active ingredients. When the pests ingest the leaves containing AVM@CS-SS-Zein, the rapid disintegration of the nanoparticles in vivo leads to a good insecticidal effect and the control rate of AVM@CS-SS-Zein on Plutella xylostella was higher than that of AVM. After 120 h of UV irradiation, the pest mortality rate of AVM@CS-SS-Zein was 46.7% while that of AVM and AVM emulsifiable concentrate was only 13.3% and 20.0%, respectively. Therefore, this pH/redox dual stimuli-responsive nanopesticide formulation achieves target control of pests and provides an efficient nanoplatform for green agriculture.