Cucurbit[7]uril-Mediated Supramolecular Bactericidal Nanoparticles: Their Assembly Process, Controlled Release, and Safe Treatment of Intractable Plant Bacterial Diseases

Abstract

A safe, biocompatible, and stimuli-responsive cucurbit[7]uril-mediated supramolecular bactericidal nanoparticle was fabricated by encapsulating a highly bioactive carbazole-decorated imidazolium salt (<b>A</b>_<b>1</b>, EC₅₀ = 0.647 μg/mL against phytopathogen <i>Xanthomonas oryzae</i> pv <i>oryzae</i>) into the host cucurbit[7]uril (CB[7]), thereby leading to self-assembled topographies from microsheets (<b>A</b>_<b>1</b>) to nanospheroidal architectures (<b>A</b>_<b>1</b>@CB[7]). The assembly behaviors were elucidated by acquired single-crystal structures, ¹H NMR, ITC, and X-ray powder diffraction experiments. Complex <b>A</b>_<b>1</b>@CB[7] displayed lower phytotoxicity and could efficiently switch on its potent antibacterial ability via introducing a simple competitor 1-adamantanamine hydrochloride (AD). <i>In vivo</i> antibacterial trials against rice bacterial blight revealed that <b>A</b>_<b>1</b>@CB[7] could relieve the disease symptoms after being triggered by AD and provide a workable control efficiency of 42.6% at 100 μg/mL, which was superior to bismerthiazol (33.4%). These materials can provide a viable platform for fabricating diverse stimuli-responsive supramolecular bactericides for managing bacterial infections with improved safety.