A triple-stimuli-responsive dendritic mesoporous silica nanopesticide delivery system for sustained control of Plutella xylostella

Traditional pesticide nanocarriers often have limited pore sizes and pore volumes, which can restrict pesticide loading and hinder precise control over release, which in turn affects pest control efficacy. In this study, dendritic mesoporous silica nanoparticles (DMSNs) with large mesopores and high pore volume were used as pesticide carriers. Bis[3-(triethoxysilyl)propyl] tetrasulfide (TESPT) was co-condensed into the silica framework to introduce redox-cleavable tetrasulfide bonds, yielding tetrasulfide-functionalized DMSN (SS-DMSN). Chlorfenapyr was loaded into the dendritic mesopores, and the particle surface was capped with carboxymethyl-β-cyclodextrin (CM-β-CD), thereby constructing a triple-stimuli-responsive pesticide nanodelivery system (CF@SS-DMSN@CD) responsive to pH, redox conditions and amylase. Morphological and physicochemical characterization indicate that CF@SS-DMSN@CD was successfully prepared and exhibits a high pesticide loading content (33.0%). Release behavior studies demonstrate that this delivery system enables on-demand controlled release of the pesticide under alkaline pH, reducing conditions, and in the presence of amylase. Meanwhile, the CM-β-CD layer significantly improves the wetting and spreading behavior of droplets on leaf surfaces. In vivo fluorescence distribution studies revealed pronounced intestinal accumulation and broader distribution of FITC-labeled CF@SS-DMSN@CD in diamondback moth larvae, while insecticidal bioassays demonstrated improved and prolonged insecticidal activity. Safety evaluation results showed that this delivery system exhibits low toxicity to non-target organisms (zebrafish and earthworms) and has no significant adverse effects on soil microbial community structure or crop growth. Overall, this study combines the mesoporous structural advantages of DMSN with the triple-stimuli-responsive properties synergistically regulated by the tetrasulfide bond and CM-β-CD, providing a feasible design approach for the development of highly efficient, precise, and environmentally friendly pesticide nanodelivery systems.