β-Cyclodextrin/Amantadine Co-Assembled Hollow Nanocapsules Realize the Rapid Leaf Adhesion and Bacterial Biofilm Disassembly for Rice and Citrus Protections

Abstract

A superior bactericide to accomplish its efficient bactericidal function requires breaking through stubborn biofilm barriers and achieving efficient leaf adsorption. To overcome this challenge, supramolecular self-assembly strategies are employed to fabricate multifunctional aggregates. Herein, a versatile supramolecular inclusion—AdA8@β-CD is constructed by loading an amantadine-modified bactericidal structure (AdA8) into β-cyclodextrin (β-CD) via host–guest recognition driving force, which spontaneously self-assembles into biocompatible hollow nanocapsules. This smart optimization not only allows the bactericides to quickly stay on the hydrophobic leaves, preventing their droplets from splashing and bouncing but also improves the performance of removing biofilm barriers. At a lower concentration of 5 µg mL⁻¹, the disruption rate of AdA8@β-CD to Xanthomonas biofilm reaches 78.3%. Moreover, AdA8@β-CD enhances the limitation of bacterial motility and extracellular enzyme secretion, thereby reducing bacterial colonization and pathogenicity. These reformative properties are undoubtedly transmitted to in vivo activity, providing corresponding preventive efficacies of 51.1% and 73.2% against rice bacterial blight and citrus canker at 200 µg mL⁻¹, which are notably better than those of traditional agrochemicals—thiodiazole-copper-20%SC (33.9%/37.4%), kasugamycin (28.7%), and AdA8 itself (43.8%/45.3%). Furthermore, this oligosaccharide-coated bactericide—AdA8@β-CD exhibits good biosafety and is more eco-friendly. This study is instructive for the creation of multifunctional green agrochemicals.