An amphiphilic carboxymethyl chitosan-based nanopesticide delivery system with enhanced foliar deposition for improved insect-repellent and antibacterial efficacy.

Abstract

BACKGROUND The significant loss of dosage during pesticide interfacial transfer notably undermines bioavailability, posing a critical challenge to sustainable agriculture. Designing pesticide formulations with efficient foliar deposition facilitates reduced application rates and enhanced efficacy. RESULTS In this study, methyl-bis(trimethylsilyloxy)silicon (TSS) was grafted onto carboxymethyl chitosan (CMCS) via a free radical polymerization reaction, followed by self-assembly to form an amphiphilic carrier (C-Ax-Ty). The carrier then encapsulated eugenol (Eug) through hydrophobic interactions, resulting in the rational construction of the amphiphilic carboxymethyl chitosan-based nanopesticide delivery system (Eug@C-Ax-Ty). The regulation of TSS addition during carrier preparation significantly reduced dynamic surface tension while simultaneously increasing the viscosity of the solutions. Droplet impact dynamics evaluation confirmed that C-Ax-Ty effectively mitigated rebound behavior during high-speed collisions with hydrophobic surfaces. Notably, Eug@C-Ax-Ty exhibited superior dynamic wettability, as demonstrated by impact dynamics analysis and energy conversion analysis. Leveraging the enhanced foliar deposition ability and delayed volatilization of Eug, vegetables treated with Eug@C-A0.4-T1.0 demonstrated improved antifeedant activity against Spodoptera litura. Moreover, Eug@C-Ax-Ty exhibited significantly enhanced antibacterial activity against foodborne Staphylococcus aureus compared to Eug, while also demonstrating reduced phytotoxicity and minimal inhibition of seed germination. CONCLUSION This study provides theoretical insights for enhancing the foliar deposition of nanopesticide formulations and improving the bioavailability of plant essential oils, thus offering promising applications in sustainable agriculture. © 2025 Society of Chemical Industry.