Preparation of silica carriers with cocklebur-like structure by flash nanoprecipitation for enhanced foliar affinity and responsive pesticide delivery.

Background: Designing nanocarriers with specific biomimetic topological structures to enhance the frictional interaction of pesticides on the target plant leaves is an effective strategy to improve pesticide retention and utilization on plant foliage. However, complex and discontinuous nanocarrier preparation processes limit their large-scale production.

Results: Herein, we have successfully synthesized the uniform cocklebur-like silica nanoparticles (CSNs) using the flash nanoprecipitation (FNP) technique. Then, a pH-responsive pesticide delivery system (AZOX@CNP-Cu) was devised to control the release of azoxystrobin (AZOX) based on CSNs as the porous carriers and polydopamine (PDA) chelated with copper ions (Cu) as the capping agent. Detailed investigations showed that AZOX@CNP-Cu has a strong retention on cucumber leaves, mainly benefiting from the spike structure of CSNs, which can form a "cocklebur adhesion effect" with the micro/nanostructures of the plant target leaf surfaces. AZOX@CNP-Cu demonstrated a pesticide loading efficiency of 28.06 wt% and pH-responsive behavior, showing the fastest release under acidic conditions (pH 5.7). Moreover, antimicrobial experiments indicated that the AZOX@CNP-Cu exhibits sustained efficacy against Botrytis cinerea while maintaining cucumber growth without notable harm.

Conclusions: This study proposes a scalable and efficient approach for designing nanostructured pesticide delivery systems with modulated topology, enabling large-scale fabrication of functional nanoparticles and improved pesticide retention. © 2025 Society of Chemical Industry.