Incorporation of a pyrethroid-based insecticide system into regenerated cellulose: interfacial interactions and effect on fiber formation

Insecticide treated nets (ITNs) are a key tool for controlling vector-borne diseases, such as malaria. However, they are traditionally made of non-renewable polymeric materials, which lack sustainability and longevity. The goal of this research is to address this issue by developing renewable, bio-based fibers that can carry insecticides while remaining suitable for netting fabric, using readily available and abundant cellulose as a raw material. To achieve this, understanding the underlying interactions between insecticides and cellulose is necessary, especially under the dissolution and regeneration conditions. Permethrin, a type of pyrethroid insecticide used in ITNs to kill malaria mosquitoes, is often mixed with piperonyl butoxide (PBO) to combat insecticide resistance. In this study, the adsorption of permethrin and PBO onto cellulose model surfaces treated with two potential direct dissolution solvents (deep eutectic solvent and ionic liquid), which yielded different allomorphs of cellulose, and was examined using surface-sensitive methods. The insecticides were then incorporated into the ionic liquid containing dissolved cellulose, processed into fiber via dry-jet wet spinning, and evaluated for mechanical performance and insecticide retention.