Gemini 12-8-12/β-CD Spreading Agent: A High-Efficiency Pesticide Delivery System for Enhanced Antifungal Activity on Soybean Leaves

Although the widespread utilization of fungicides has substantially mitigated the fungal threat to crop yields and food security, their efficacy and bioavailability remain severely hampered by the superhydrophobic nature of crop leaves. Aiming to overcome these limitations, we engineer a host-guest complex between β-cyclodextrin and gemini surfactants (12-<i>n</i>-12, <i>n</i> = 4, 6, 8) to construct supramolecular surfactants that encapsulate the broad-spectrum fungicide boscalid and exhibit high interfacial activity. Among these supramolecular complexes, the 12-8-12/β-CD system rapidly adheres to the leaf surface and effectively suppresses droplet retraction through quantitative analysis and SEM images. Furthermore, the chosen 12-8-12/β-CD@Boscalid demonstrates exceptional wetting properties, minimal droplet rebound, superior deposition stability, and strong adhesion on hydrophobic leaf surfaces compared to the commercially available Boscalid formulation (BASF). Remarkably, 12-8-12/β-CD@Boscalid achieves superior in vitro and in vivo antifungal efficacy against <i>Botrytis cinerea</i> (94.2% inhibition rate) and <i>Rhizoctonia solani</i> (92.5% inhibition rate) as well as excellent biocompatibility, outperforming its counterparts. In conclusion, the 12-8-12/β-CD@Boscalid provides a theoretical basis and practical direction for reducing pesticide dose while increasing efficiency, which presents a promising approach for designing eco-friendly, cost-efficient, and high-performance supramolecular fungicides to combat agricultural pathogens.