Fabrication of Multifunctional Three-Component Supramolecular Nano-Biscuits via Two Macrocycles-Involved Self-Assembly for Rice, Citrus and Kiwifruit Protections.

Abstract

Bacterial plant diseases, worsened by biofilm-mediated resistance, are increasingly threatening global food security. Numerous attempts have been made to develop agrochemicals that inhibit biofilms, however, their ineffective foliar deposition and difficulty in removing mature biofilms remain major challenges. Herein, multifunctional three-component supramolecular nano-biscuits (NI6R@CB[7]@β-CD) are successfully engineered via ordered self-assembly between two macrocycles [cucurbit[7]uril (CB[7]), β-cyclodextrin (β-CD)] and (R)-2-naphthol-based bis-imidazolium bromide salt (NI6R). This macrocycles-involved bactericidal material combines many advantages. 1) Alleviate the off-target movement of droplets on hydrophobic blade surfaces. 2) Enhance the biofilm-disrupting ability. At a low-dose of 4.44 µg mL^-1, the inhibition rate of biofilm formation reached 78.3%. At 35.5 µg mL^-1, the potency to remove mature biofilms reached 77.6%. 3) Efficiently hinder bacterial reproduction, swimming, extracellular polysaccharide production, extracellular enzyme secretion, and virulence to plants. These superior characteristics are undoubtedly transmitted to the in vivo control effect. At 200 µg mL^-1, this smart material exhibits superior control efficiencies of 49.6%/65.0%/85.4% against three kinds of bacterial diseases (rice leaf blight, citrus canker, and kiwifruit canker), respectively, surpassing the commercial bactericide-thiodiazole-copper-20%SC (33.6%/41.5%/43.2%) and NI6R (40.3%/51.2%/71.2%). Furthermore, NI6R@CB[7]@β-CD is biosafe to non-target organisms. This study is instructive for constructing multifunctional agrochemicals in sustainable crop protection.