High-gravity driven construction of copper ion-prothioconazole nanocomplexes: photostabilization and synergistic antifungal efficacy

Prothioconazole (hereinafter referred to as Pro), as a highly efficient and broad-spectrum triazole fungicide, the application is limited by its poor water solubility, insufficient photostability, and potential environmental risks. Although nanotechnology provides a novel pathway to enhance pesticide performance, the existing carrier-dependent nano-formulations generally have problems such as complex preparation processes, high raw material costs, and carrier environmental residue risk. Therefore, in this study, copper ion(Cu²⁺)-prothioconazole nanocomplexes (Cu-EL80-Pro) were prepared by high-gravity technology without external carrier. The effects of process conditions, Cu²⁺ source and content on particle size and distribution were systematically investigated. Its photostability, antifungal activity and biological safety were comprehensively evaluated. The results showed that the resulting Cu-EL80-Pro exhibited an mean particle size of 30 nm with a uniform particle size distribution (polydispersity index, PDI < 0.2). After 24 h of UV irradiation, the residual rate of Pro in Cu-EL80-Pro still remained as high as 53.14%, and its half-life was prolonged by more than 12-fold compared to that of the prothioconazole and the nanosystem without Cu²⁺, showing excellent photostability. The EC₅₀ value of the complex against Botrytis cinerea was 0.339 mg/L, and the toxicity was increased by approximately 40% compared with the nanosystem without Cu²⁺, demonstrating significant synergistic effects. It had no significant inhibition on wheat seed germination and seedling growth, indicating good biological safety. This study successfully achieved the controllable preparation of pesticide-metal ion nanocomplexes using high-gravity technology, providing a new strategy for the efficient utilization of poorly soluble pesticides and the large-scale development of green nanopesticides.