Development of pH-responsive dynamic liposomes for enhancing pesticide deposition and smart on-demand delivery

Various strategies have been developed to reduce pesticide usage while enhancing efficacy. However, the current formulation systems face several challenges such as complex system compositions, low encapsulation efficiency, unavoidable use of organic solvents, poor wettability and retention, and particularly the difficulty in addressing these issues simultaneously, which limits their practical applications.

An imine-based dynamic covalent phospholipid was synthesized to construct pH-responsive avermectin (PC@AVM) liposomes to achieve nanodispersion, complete wettability, efficient deposition, and precise on-demand delivery. Under neutral or alkaline conditions, AVM is released slowly from the liposomes, whereas rapid release occurs under acidic conditions. And the formed liposomes exhibit excellent storage stability and photostability. The residual rate of PC@AVM liposomes is about 30% higher than that of unencapsulated AVM after 75 h of ultraviolet (UV) irradiation, because the hydrophobic AVM can be embedded in the hydrophobic regions of phospholipid bilayers to prevent photodegradation. The PC@AVM liposomes exhibit strong adhesion to leaf surfaces, resulting in exceptional rainfastness with a retention rate of nearly 90% after washing. Meanwhile, the vesicle-like liposome can strongly interact with surface microstructures/nanostructures during the high-speed impact process, thereby also suppressing splashing and ensuring complete deposition of droplets on hydrophobic surfaces. Moreover, PC@AVM liposomes show long-term insecticidal activity and exhibit excellent biosafety for environmental organisms.

This work provides an innovative carrier and constructs multifunctional, on-demand release pesticide liposomes, thereby potentially reducing pesticide use and promoting the development of sustainable agriculture. © 2025 Society of Chemical Industry.