Adding Flying Wings: Butterfly-Shaped NIR-II AIEgens with Multiple Molecular Rotors for Photothermal Combating of Bacterial Biofilms

Abstract

The ever-increasing threats of multidrug-resistant bacteria and their biofilm-associated infections have bred a desperate demand for alternative remedies to combat them. Near-infrared (NIR)-absorbing photothermal agent (PTAs)-mediated photothermal therapy (PTT) is particularly attractive for biofilm ablation thanks to its superiorities of noninvasive intervention, satisfactory antibacterial efficiency, and less likelihood to develop resistance. Herein, three butterfly-shaped aggregation-induced emission luminogens (AIEgens) with balanced nonradiative decay (for conducting PTT) and radiative decay (for supplying fluorescence in the NIR-II optical window) are rationally designed for imaging-assisted photothermal obliteration of bacterial biofilms. After being encapsulated into cationic liposomes, AIEgens-fabricated nanoparticles can eradicate a wide spectrum of biofilms formed by Gram-positive bacteria (methicillin-resistant <i>Staphylococcus aureus</i> and <i>Enterococcus faecalis</i>) and Gram-negative bacteria (<i>Escherichia coli</i> and <i>Pseudomonas aeruginosa</i>) upon an 808 nm laser irradiation. <i>In vivo</i> experiments firmly demonstrate that the NIR-II AIE liposomes with excellent biocompatibility perform well in both the <i>P. aeruginosa</i> biofilm-induced keratitis mouse model and the MSRA biofilm-induced skin infection mouse model.