The key factors of solid nanodispersion for promoting the bioactivity of abamectin.

ABSTRACT

Solid nanodispersion (SND) is an important variety of nanopesticides which have been extensively studied in recent years. However, the key influencing factors for bioactivity enhancement of nanopesticides remain unclear, which not only limits the exploration of relevant mechanisms, but also hinders the precise design and development of nanopesticides. In this study, we explored the potential of SND in enhancing the bioactivity of nanopesticides, specifically focusing on abamectin SND prepared using a self-emulsifying-carrier solidifying technique combined with parameter optimization. Our formulation, consisting of 8% abamectin, 1% antioxidant BHT (2,6-di-tert-butyl-4-methylphenol), 12% complex surfactants, and 79% sodium benzoate, significantly increased the pseudo-solubility of abamectin by at least 3300 times and reduced its particle size to a mere 15 nm, much smaller than traditional emulsion in water (EW) and water-dispersible granule (WDG) forms. This reduction in particle size and increase in surface activity resulted in improved foliar adhesion and retention, enabling a more efficient application without the need for organic solvents. The inclusion of antioxidants also enhanced photostability compared to EW, and overall stability tests confirmed SND's resilience under various storage conditions. Bioactivity tests demonstrated a marked increase in toxicity against diamondback moths (Plutella xylostella L.) with abamectin SND, which exhibited 3.7 and 7.6 times greater efficacy compared to EW and WDG, respectively. These findings underscore the critical role of small particle size, high surface activity, and strong antioxidant properties in improving the performance and bioactivity of abamectin SND, highlighting its significance in the design and development of high-efficiency, eco-friendly nanopesticides and contributing valuably to sustainable agricultural practices.