Self-assembling biocompatible core-shell nanocapsules with versatile surface functionalities for precise pesticide delivery

Abstract

Traditional pesticide formulations often rely heavily on surfactants, which pose significant environmental hazards. Additionally, their production involves synthetic chemicals and generates large amounts of by-products, further exacerbating the ecological burden. Consequently, there is an urgent need to develop an environmentally friendly nanodelivery system that can enhance the efficacy of pesticides while minimizing both environmental and health risks. Here, a metal mineralization strategy was employed to reinforce the self-assembly of biocompatible nanocapsules with versatile surface functionalities for smart delivery of lambda-cyhalothrin (LCT). During the homogenization process, carboxymethyl cellulose (CMC), chitosan (COS), and copper ions co-precipitated at the oil–water interface and self-assembled into core–shell nanocapsules, acquiring the desired surface functionality through electrostatic forces, hydrogen bonding, and metal coordination. The resulting LCT@CMC@COS-Cu nanocapsules demonstrated high encapsulation efficiency for LCT and superior pesticide delivery performance targeting lepidopteran pests, enabled by the alkaline- and cellulase-responsive polysaccharide-based capsule shells. Foliar washing experiments demonstrated that LCT@CMC@COS-Cu adhere efficiently to the surface of soybean leaves and achieved bidirectional transport through the plant’s vascular system. Notably, LCT@CMC@COS-Cu significantly extended the half-life of LCT under UV irradiation by 9.9-fold compared to technical LCT. In pot experiments, the mortality rate of Spodoptera litura larvae treated with LCT@CMC@COS-Cu (56.67 %) was significantly higher than that of the LCT suspension concentrate (16.67%) after 12 days, implying prolonged efficacy. Safety evaluations of the nano-formulation were conducted using plant, zebrafish, Harmonia axyridis, and in vivo mice models, further confirming its excellent safety profile. This study presents an eco-friendly and versatile insecticide nano-formulation.