Fabrication of pH-responsive nanoparticles for co-delivery of fungicide and salicylic acid with synergistic antifungal activity

Stimuli-responsive co-delivery nanopesticides with different action mechanisms have received widespread attention due to the improved bioactivity, long effective duration, and reduced risks to the environment. Herein, fungicide tebuconazole (TEB) and plant immune inducer poly(salicylic acid) (PSA) co-assembled nanoparticles (TP NPs) are fabricated through non-covalent interactions without the use of any adjuvants. The results show that the obtained TP NPs have excellent physicochemical properties, displaying uniform morphology with an average particle size of 152 nm, low PDI (0.064), and high surface activity. The TP NPs exhibit acid-responsive behaviors, enabling the intelligent release of active ingredients in the specific acidic microenvironment caused by the invasion of plant pathogens. In vitro fungicidal activities of TP NPs are 1.9 and 1.6 times higher than TEB technical against Sclerotinia sclerotiorum and Fusarium graminearum respectively. Additionally, the stimuli-responsive co-delivery fungicidal nanosystem not only has a longer effective duration compared to both TEB technical and TP Mix but also significantly reduces the genetic toxicity of TEB to the plants. Therefore, this fungicide and plant immune inducer co-delivery nanosystem provides a novel strategy for development of multimode synergetic nanopesticide and sustainable plant disease management.